JPH0544194A - Sizing agent for production of paper and method for sizing surface of paper - Google Patents

Abstract

PURPOSE:To provide the subject sizing agent comprising an aqueous dispersion containing a specific ketene dimer and a specified water-soluble mixture, having a zeta potential within a prescribed range, excellent compatibility and sliding- preventing property, and useful for pulp, etc. CONSTITUTION:The objective sizing agent comprises a water dispersion having (A) a ketene dimer of the formula (R1, R2 are 8-24C hydrocarbon) and (B) a water-soluble mixture comprising a processed starch (e.g. a low mol.wt. starch produced by treating tapioca starch with hydrochloric acid) having a total colloid equivalent of -15.0 to +0.05meq/g and an anionic polycondensation product (e.g. styrene-maleic acid copolymer) and having a Brookfield viscosity of 2-100 poises measured in a 3wt.% aqueous solution at 30 deg.C and has a zeta potential zeta of -30 to +5mV. The sizing agent is preferably used for sizing the surface of paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking sizing agent and a papermaking surface sizing method. More specifically, the present invention relates to a papermaking sizing agent and a surface sizing method, which have good compatibility with a sizing agent used in combination and are excellent in paper slip resistance.

[0002]

2. Description of the Related Art Conventionally, acid sizing using rosin or reinforced rosin (maleated rosin) in combination with aluminum sulfate has been generally performed as a sizing method for paper and paperboard. On the other hand, in recent years, neutral sizing has been introduced from the viewpoints of closed white water in the papermaking process, use of inexpensive and highly white calcium carbonate as a filler, use of broke containing the same, and coat broking treatment. ing. As the sizing agent used for this neutral sizing, ketene dimer sizing agents, substituted cyclic dicarboxylic acid anhydride sizing agents, etc. are known, but they are expected to have strong sizing ability due to their ease of use and addition in small amounts. Because of its ability, ketene dimer size is widely used.

[0003]

However, the ketene dimer-based sizing agent still has the following drawbacks. The first drawback is that the conventional ketene dimer sizing agent has a strong cationic property, so that it has poor compatibility with the anionic oxidized starch used together during the surface sizing, resulting in agglomerates. Usually, in the process of manufacturing paper or paperboard, surface sizing is performed by applying a surface sizing agent to the paper after forming the paper layer using a size press, size tab, gate roll coater, calender, etc., and drying it if necessary. This surface sizing is intended to improve the printability by increasing the surface strength of the paper in addition to imparting size properties to the paper, starch derivatives such as starch and oxidized starch, cellulose derivatives such as carboxymethyl cellulose, polyvinyl alcohol and anions. Natural or synthetic water-soluble polymeric substances such as modified polyacrylamide are used, and among these, oxidized starch modified with various agents such as oxygen and ammonium persulfate is often used. When these water-soluble polymer and surface sizing agent are used in combination, both aqueous solutions are mixed, and a part of the mixed aqueous solution is usually circulated at a high temperature of 50 to 70 ° C. for application. At this time, ketene dimer sizing agent having strong cationic property and anionic oxidized starch produce aggregates, and when the resulting aggregates cause stains on paper machine parts such as coating rolls, the stains are produced on the product. The transfer may occur, the surface smoothness of the paper may be impaired, or the paper may be broken depending on the case, resulting in a problem that productivity is remarkably reduced. The second drawback is that when the ketene dimer size is sized on the surface of the paper, the coefficient of friction of the paper surface decreases. Therefore, there occurs a problem that a slip phenomenon occurs during transportation after paper making is dried or after box making, and safety, work efficiency, and product value are significantly adversely affected.

In order to obtain an aqueous emulsion of a ketene dimer sizing agent, ketene dimers have been disclosed in Japanese Patent Laid-Open No. 3-167391 as anionic substances such as sodium lignosulfonate, calcium lignosulfonate and sodium salt of naphthalenesulfonic acid. It is disclosed that a dispersant and / or an emulsifier and, if necessary, anionic polyacrylamide, anionic starch or colloidal silica are used in combination to increase or modify the anionic charge density to stabilize an aqueous emulsion thereof. There is. However, such a low-molecular-weight anionic dispersant and / or emulsifier alone is not only inferior in storage stability (hydrolysis resistance) of ketene dimer due to adsorption-desorption equilibrium, but also used in combination with anionic starch or the like. However, unless the colloid equivalent, the blending ratio, and the viscosity of the mixture are controlled within the predetermined ranges, a strong protective layer is not formed and a stable emulsion cannot be obtained. Further, the regulation of the ζ potential of the aqueous emulsion is important, and if it is not controlled within a predetermined range, not only the sufficient size performance will not be exhibited, but also the effect of preventing slippage of paper will be ineffective.

Although the ketene dimer type sizing agent has excellent properties such that a sizing effect appears at a low addition amount and a high sized paper is obtained, its use is limited due to the above reasons. is the current situation. Therefore, an object of the present invention is to provide a sizing agent for papermaking and a surface sizing method, which have good compatibility with a sizing agent used in combination and are excellent in slip resistance of paper.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a mixture of a specific processed starch and an anionic polycondensate was used as a dispersant during surface sizing. , Compatibility with the pasting agent by using a ketene dimer sizing agent in which a water-soluble mixture having a specific viscosity is used and its zeta potential (hereinafter referred to as ζ potential) is controlled within a specific range Further, they have found that the anti-slip property of paper can be improved and completed the present invention. That is, the present invention is represented by the general formula (1)

[0007]

[Chemical 2]

(In the formula, R ₁ and R ₂ are each 8 to 24 carbon atoms.
Is a hydrocarbon group. ) Ketene dimer (a)
And a mixture of processed starch and anionic polycondensate having a total colloid equivalent of -15.0 to +0.05 meq / g, the 3% by weight aqueous solution of which has a Brookfield viscosity of 2 to 100 centipoise at 30 ° C. Of a water-based dispersion containing a mixture (b) and a ζ potential in the range of −30 mV to +5 mV, and a paper sizing agent using such a paper sizing agent. The present invention provides a surface sizing method characterized by performing surface sizing. In the present invention, the colloid equivalent is a physicochemical value obtained by measuring the ionizing group of the polymer electrolyte itself by a colloid titration method, the low molecular electrolyte and unreacted cationizing agent, anionizing agent not exist. Further, the ζ potential is a physicochemical value obtained by a conventional electrophoresis method.

Next, the present invention will be described in detail. The ketene dimer constituting the present invention is a compound represented by the above general formula (1), and any known ketene dimer can be used.
In the general formula (1), R ₁ and R ₂ represent various hydrocarbon groups having 8 to 24 carbon atoms, preferably 12 to 22 carbon atoms. Examples of these hydrocarbon groups include alkyl groups, alkenyl groups and aryl groups, but are not particularly limited. Examples of the alkyl group include octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl group and the like, and examples of the alkenyl group include octenyl, decenyl, dodecenyl, tetradecenyl, hexadecenyl, octadecenyl, eicosenyl group and the like, and the aryl group as Examples thereof include octaphenyl, nonylphenyl and dodecylphenyl groups, and among these, an alkyl group is preferable. Further, in terms of physicochemical constants, the melting point of the ketene dimer is preferably 20 to 80 ° C., and if R ₁ and R ₂ are hydrocarbon group compositions within the above range, they may be used alone or in combination of two or more. Can be used. Here, the melting point means an ascending melting point, which is a value measured by a capillary method. In order to obtain the ketene dimer represented by the above general formula (1) according to the present invention, for example, a dehydrochlorination reaction of a fatty acid chloride obtained by reacting a fatty acid mixture which is a raw material with phosphorus trichloride A known method performed in the presence of an amine catalyst may be applied.

The water-soluble mixture (b), which is one of the essential components constituting the sizing agent of the present invention, has a total colloid equivalent of -1.
5.0 to +0.05 meq / g of a mixture of processed starch and anionic polycondensate, 3% by weight of which is an aqueous solution at 30 ° C.
It has a Brookfield viscosity of -100 centipoise. The mixing ratio of the modified starch and the anionic polycondensate is preferably in the range of 0.5 to 100 parts by weight of the anionic polycondensate with respect to 0.05 to 100 parts by weight of the modified starch. In the present invention, the viscosity of this water-soluble mixture (b) is important,
It is necessary that the Brookfield viscosity of the 3 wt% aqueous solution at C is between 2 and 100 centipoise.
A water-soluble mixture having a Brookfield viscosity of less than 2 centipoise in a 3% by weight aqueous solution at 30 ° C. has an emulsifying power but is inferior in dispersion stability. On the other hand, a water-soluble mixture exceeding 100 centipoise markedly reduces the emulsifying property of the ketene dimer (a).

It is important for the processed starch according to the present invention that the total sum of colloid equivalents is in the range of -15.0 to +0.05 meq / g, and especially for those having a colloid equivalent of less than -15.0 meq / g. , But it is difficult to obtain it due to the reactivity of starch.
If the colloid equivalent is within this range, a cationic group,
Known products such as modified starch having an anionic group or both groups, or non-ionic modified starch having neither a cationic group nor an anionic group can be used. Examples of the non-ionic processed starch include, for example, raw starch that is oxidatively decomposed with sodium hypochlorite or hydrogen peroxide or hydrolyzed with a mineral acid such as hydrochloric acid, nitric acid, or sulfuric acid to cleave the starch main chain to reduce starch. Examples of molecularized and anionic modified starches include monochloroacetic acid, propane sultone, 3-
Etherifying agents such as sodium chloro-2-hydroxy-sulfonate, orthophosphoric acid, sodium tripolyphosphate, phosphoric anhydride, trimetaphosphoric acid, hexametaphosphate, maleic anhydride, succinic anhydride, phthalic anhydride, and other dibasic anhydrides Modified with anionizing agents such as esterifying agents such as tribasic acid anhydrides such as trimellitic anhydride, and cationic modified starches include 2-diethylaminoethyl chloride and 3-diethylamino-1. , 2-
Those which have been cationized with a cationizing agent such as epoxypropane, 3-dibutylamino-1,2-epoxypropane, 2-chloroethyltrimethylammonium chloride, glycidyltrimethylammonium chloride, and amphoteric modified starch include the above anions. Well-known agents such as those in which both an agent and a cationizing agent are introduced can be used.
Examples of the raw material starch include raw starch such as corn, potato, tapioca, wheat and rice. The modified starch may be reduced in molecular weight or may be introduced with a functional group such as a hydroxyalkyl group unless the sum of colloid equivalents or the viscosity of the water-soluble mixture (b) is out of the range specified in the present invention. Further, one kind may be used alone, or two or more kinds may be used as a mixture.

The anionic polycondensate according to the present invention preferably has an aromatic ring in the molecule, for example,
Styrenes such as styrene, α-methylstyrene, α, 2-dimethylstyrene, α, 3-dimethylstyrene, α, 4-dimethylstyrene, α, 2,4-trimethylstyrene, α-methyl-4-chlorostyrene, etc. , Maleic anhydride, maleic acid, maleic acid monochloride, maleic acid dichloride, propyl maleic anhydride, benzyl maleic anhydride, maleic acid monoethyl ester and other maleic acids, methyl (meth) acrylate, n-butyl (meth)
Acrylate, isobutyl (meth) acrylate, 2-
Copolymers with esters of acrylic acid or methacrylic acid such as ethylhexyl (meth) acrylate, styrenesulfonic acid monomers and salts thereof, toluenesulfonic acid, xylenesulfonic acid, naphthalenesulfonic acid, alkylnaphthalenesulfonic acid, phenol Examples thereof include sulfonic acid, cresol sulfonic acid, schafer acid, creosote oil sulfonate, and formalin condensates of mixtures thereof and salts thereof. The above-mentioned anionic polycondensate may be used singly as long as the viscosity of the water-soluble mixture (b) and the ζ potential of the ketene dimer sizing agent do not deviate from the ranges specified in the present invention. It may be used as a mixture of two or more species.

The ketene dimer sizing agent of the present invention, ζ
In order to control the potential in the range of -30 to +5 mV, the mixing ratio must be controlled by the ionic strength of the modified starch used and the anionic strength of the anionic polycondensate. In the present invention, it is also important that the ketene dimer size used has a zeta potential in the range of -30 to +5 mV. If the ζ potential exceeds +5 mV, the compatibility with oxidized starch and the slip resistance of paper are impaired. On the other hand, if the ζ potential is less than −30 mV, it means that there are too many anion components in the dispersion layer, which may hinder the size effect, which is not preferable.

In order to obtain the ketene dimer sizing agent according to the present invention, the order of addition of the respective constituents is important. First, the above-mentioned modified starch is added to water in an amount of 0.1 to 20% by weight, preferably 0.5 to 10% by weight. And dissolved by heating, and then 0.01-10% by weight, preferably 0.02-5, of anionic polycondensate is added to this aqueous solution.
Mix by weight. Then, the temperature is raised with sufficient stirring. The ketene dimer (a) is added in an amount of 2 to 35% by weight, preferably 10 to 20% by weight, in an aqueous solution of a mixture heated, and the ketene dimer (a) is mixed and dispersed in a molten state. At this time, the ketene dimer (a) may be added as a solid to the above aqueous solution, or may be previously melted and added. It is desirable that the temperature at the time of dispersion is not lower than the melting point of the ketene dimer (a) and not higher than 100 ° C, preferably not higher than 80 ° C. If the temperature is too high, the ketene dimer (a) may react with water to give a reaction product that has no size effect. Further, it is not necessary to add other dispersants or emulsifiers within a range that does not impair the effect of compatibility with the sizing agent used in combination with the papermaking size and surface sizing method of the present invention and the effect of preventing slippage of paper. It doesn't matter.

The particle size of the ketene dimer (a) dispersed in the dispersion of the ketene dimer sizing agent according to the present invention is generally desired to be 5 microns or less. For example, the sizing composition according to the present invention is used in a state of being dispersed in water, but the particle size of the sizing particles dispersed in water is 5 μm or less,
It is preferably 1 micron or less. If the particle size is larger than 5 microns, the stability of the dispersion may be impaired and the size effect may be reduced.
A homomixer, an ultrasonic emulsifier, a high-pressure discharge homogenizer, or the like can be used to disperse the size particles.

The surface sizing method of the present invention is carried out by performing surface sizing of paper using the above-described papermaking sizing agent of the present invention. In carrying out the papermaking surface sizing method of the present invention, there is no particular limitation,
Any conventionally known surface sizing method of coating or impregnating the ketene dimer sizing agent described above after forming a paper layer in a paper or paperboard manufacturing process can be adopted. Specifically, a sizing agent is applied to the surface of a paper by a size press, size tab, gate roll coater, calender, or the like at 0.005 to 5 g / m ² (solid content), preferably 0.01.
It may be added so as to be applied to ˜1 g / m ² . It goes without saying that the standard of the coating amount of these sizing agents must be adjusted according to the sizing degree required for the target paper. Further, in carrying out the papermaking surface sizing method of the present invention, the papermaking sizing agent according to the present invention may be used alone, and the above-mentioned water-soluble polymer substance, a surface-treating agent such as a dye, and defoaming agent. It can be used by mixing with additives such as agents in the same coating liquid. The base paper to which the surface sizing method for papermaking of the present invention is applied is not particularly limited, and various kinds of paper, paperboard and the like can be used. Further, the surface sizing method for papermaking of the present invention is hardly affected by pulp, filler, dye, internally added sizing agent, paper strength enhancer, retention improver, pH during papermaking, and the like.

[0017]

EXAMPLES The present invention will be specifically described below with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples. In the examples,% is based on weight unless otherwise specified. The colloid equivalent and ζ potential were measured by the following methods. Colloid Equivalent Measuring Method For the cationic rich processed starch, the aqueous solution of the predetermined concentration is used. On the other hand, for the anionic rich processed starch, the excess amount of 1 /
After adding the 200 N-methyl glycol chitosan solution, the initial pH was adjusted to 4 with a 2N-acetic acid solution, and toluidine blue solution was added dropwise as an indicator,
Titration with 400 N-polyvinyl potassium sulfate solution. Method of measuring ζ-potential Use a dispersion medium with pH of 8 and ionic strength I of 5.32 × 10 ^-3 (electrolyte solution with Ca concentration of 56.9ppm and Mg concentration of 8.6ppm adjusted by CaCl ₂ , MgCl ₂ and NaOH). After adjusting the concentration of the ketene dimer sizing agent to 50 ppm, the sizing agent particles were electrophoresed under an applied voltage of 80 V for measurement.

Examples 1 to 7 and Comparative Examples 1 to 5 <Preparation of ketene dimer sizing agent> The processed starch shown in Table 1 was dissolved in water by heating, and then the anionic polycondensate shown in Table 2 was added thereto. Charged and mixed. At that time, both were used so as to have the weight ratio shown in Table 4. Then, with sufficient stirring, ketene dimer obtained by using a saturated fatty acid having a carbon number distribution shown in Table 3 as a raw material was added, and melt-mixed at 70 ° C.,
Pressure (gauge pressure) using a high pressure discharge type homogenizer 2
It was emulsified at 00 kg / cm ² and further cooled to obtain a ketene dimer size. The composition and zeta potential of the obtained sizing agent are shown in Table 4.
Shown in.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

<Comparison of Compatibility with Oxidized Starch> In a 300 ml graduated cylinder, the sizing liquid so that the solid content concentration of the sizing composition shown in Table 4 is 5% and the solid content concentration of the oxidized starch is 8%. 50 g is prepared, and an air stone having a diameter of 3 cm is put therein. Bubble for 1 hour at 60 ° C, and measure the foam height after 1 hour and the amount of aggregates generated (The amount of aggregates was measured by filtering the aggregates with a 325 mesh wire mesh and measuring the solid content weight. Asked). The results obtained are shown in Table 5. The higher the foam height and the higher the weight of the agglomerates, the poorer the compatibility with the oxidized starch. The other test conditions are as shown below. Air pump: Aquarium Lamy 500S (manufactured by Five Plan) Air flow rate 800 liters / min Air stone: Uses with a diameter of 3 cm

[0024]

[Table 5]

<Comparison of anti-slip property of paper> A mixture of the sizing composition and the oxidized starch shown in Table 4 was applied to a normal weakly sized paper made by neutralization with a lab size press, The static friction coefficient of the paper was measured. The obtained results are shown in Table 6. The papermaking conditions, sizing conditions, and static friction coefficient measurement conditions are shown below.

(1) Base paper pulp: LBKP (Canadian Standard Freeness 40
0ml) Filler: Light calcium carbonate (Tamapearl 121, made by Okutama Kogyo), added by adjusting the calcium carbonate in the paper to 12%. Fixing agent: Cationic starch (CATO 302, made by Oji National), based on pulp weight Solid content 0.5% Sizing agent: Ketene dimer sizing agent (Cyrene S94, made by Kao), solid content 0.05% to pulp weight Retention aid: Cationic polyacrylamide polymer (Percoll 47, Kyowa Sangyo), pulp solids 0.02% during fixing pH to weight: 8.0 addition order: pulp - fillers - fixing agent - the sizing agent - retention aids Extract Concrete: TAPPI square type hand paper making machine press: 3.5kgw / cm ² × ² min drying : Rotary dryer, 100 ° C / 40 seconds Basis weight: 70g / m ² (2) Composition of coating sizing agent: Surface sizing agent: 0.9% Oxidized starch: 8.0% Water: 91.1% Coating amount; Solid content of surface sizing agent: 0.27g / m ² oxidation lees Solid: 2.40g / m ² (3) Size Press Press Speed: 100 m / min nip pressure: 10 kg / cm coating solution temperature at 60 ° C. (4) using the drying conditions rotary dryer, 40 seconds at 105 ° C. Dried. (5) Measurement of static friction coefficient The static friction coefficient of paper is measured using a card friction coefficient measuring machine (Kumagaya Riki Kogyo Co., Ltd.) and the values are compared. The larger the value is, the higher the anti-slip property of the paper is. The other test conditions are shown below. Specimen size 187.32 × 82.55 mm Driving distance 50 mm Weight 1000 g, 76 × 76 mm Gauge driving speed 90 cm / min Compliant with JIS C6224

[0027]

[Table 6]

Claims (3)

[Claims] 1. A general formula (1): (In the formula, R ₁ and R ₂ are each a hydrocarbon group having 8 to 24 carbon atoms.) And the total colloid equivalent is −15.0 to +0.05 meq / g. Is a mixture of modified starch and anionic polycondensate, whose 3% by weight aqueous solution is 30%.
A paper dispersion characterized by comprising an aqueous dispersion containing a water-soluble mixture (b) having a Brookfield viscosity of 2 to 100 centipoise at 0 ° C. and having a zeta (ζ) potential in the range of −30 mV to +5 mV. Sizing agent. 2. The papermaking sizing agent according to claim 1, wherein the anionic polycondensate has an aromatic ring. 3. A surface sizing method, which comprises sizing the surface of a paper using the papermaking sizing agent according to claim 1.