KR100371866B1 - Modified starch useful for paper surface sizing and a method thereof - Google Patents

Abstract

The present invention relates to a method for producing cationic starch for paper surface sizing, wherein the starch is protonated and then oxidized using hydrogen peroxide as the oxidant. When cationic starch according to the present invention is used for paper surface sizing, there is little penetration into the paper, thereby improving the surface strength opacity and printability, and reducing the anionic trash load of papermaking system during paper recycling. Can be lowered.

Description

Modified starch useful for paper surface sizing and a method

The present invention relates to a modified starch having properties suitable for paper surface sizing and a method for producing the same.

Oxide starch for sizing of paper surface, which is widely used at present, has excellent geological stability and penetrates into the paper to increase the internal bonding force, but due to absorption into the paper, the surface strength improvement is low, and the printability and opacity are low. There are disadvantages to losing. In addition, when recycling the paper sized with the oxidized starch, the oxidized starch acts as an anionic trace, increasing the COD load in the system, reducing the effect of the retention enhancer, and causing loss of raw materials.

Therefore, in order to solve this problem, it is required to develop modified starch for surface sizing that does not induce anionic trash load of papermaking system because it has less penetration into paper and improves surface strength, opacity and printability. It is becoming.

European Patent Application Publication No. 824161A describes a method for producing modified starch suitable for surface sizing or coating composition by introducing amphifectin into cationic starch, the main component of which is cationic and hydroxyalkyl or alkyl ester groups, or modified to have amphoteric properties. Doing. European Patent Application Publication 562927A describes a method for preparing amphoteric starches having both cationic and carboxyl groups by selectively oxidizing a cationic starch having a terminal reducing group with hydrogen peroxide and bromic acid or bromine. have. Japanese Patent Application Laid-Open No. 60045698A describes a method for preparing starch having amphoteric properties by introducing a compound having a carboxyl group and a compound having a vinyl group in the presence of sodium hydroxide in the starch.

Japanese Patent Application Laid-Open No. 7243192A describes a method of surface sizing newspaper paper by adjusting the viscosity by enzymatically treating cationic starch. Japanese Patent Application Laid-Open No. 11107188A describes a method of increasing the strength of toilet paper and the like by adjusting the viscosity by enzymatically treating cationic starch and adding it to paper. All of these conventional techniques are techniques for low viscosity by enzymatically treating cationic starch. In order to achieve the desired viscosity, the cationic starch must be gelatinized at low concentration and reacted at high temperature to achieve the desired viscosity. There is a problem.

In US Patent 4373099, a starch slurry is denatured by adding a protonating agent and a water-soluble oxidizing agent such as persulfate, sodium hypochlorite, and hydrogen peroxide at the same time, and then cooking for several hours at a temperature of 48.8 to 93.3 ° C, or lowering the cooked starch to It describes a method for producing a deluxe cationic starch paste by modifying at a high temperature of 48.8 ~ 93.3 ℃ by adding a positive agent and a water-soluble oxidant at the same time. When using this method it is difficult to control the viscosity as well as a disadvantage that must be cooked to obtain a low viscosity.

Procter [Cellul. Sources Exploit, 129-136, edited by Kennedy, John F., Phillips, Glyn O., Williams, Peter A., Harwood, London, UK, (1990)], and Glitten Boomerrg et al. [Coat./Papermakers Conf] ., Volume 2, 705-713, TAPPI Press, Atlanta, Ga, (1998), showed that surface strength, printability, opacity, etc., which are disadvantages of conventional oxidized starch, are greatly improved by using cationic starch for surface sizing of paper. Published the results. However, the cationic starch presented by them still contained anionic groups, resulting in a decrease in surface residues and insufficient surface strength. In addition, the viscosity of the prepared cationic starch was higher than 50-100cps.

Therefore, there is a need for a technique that is cationic and has an advantageous process, that is, a viscosity of about 10-20 cps.

The present invention provides a method for preparing a low viscosity cationic modified starch.

The present invention provides a method for preparing cationic starch for surface sizing.

1 shows a confocal scanning micrograph of a paper surface sized with cationic starch.

2 shows a confocal scanning micrograph of a paper surface sized with starch oxide.

3 is a graph showing a result of comparing the ratio of starch eluted in white water after recycling surface-sized phage.

4 is a graph comparing white water COD load according to starch elution.

FIG. 5 is a graph comparing the retention effect of fines and fillers of phage surface-sized with cationic starch and oxidized starch.

The present invention relates to a method for producing cationic starch for paper surface sizing, which comprises reacting starch with oxidation followed by oxidation.

In the present invention, the starch may be corn starch, waxy corn starch, potato starch, rice starch, wheat starch, tapioca starch, sweet potato starch, cassava starch and the like.

In the present invention, the protonation reaction may be carried out under the protonation reaction conditions generally performed in the modified starch production process. For example, the powdered starch is dissolved in water to form a slurry, followed by a temperature of 40 to 45 ° C and a pH of 11 to 12. It refers to a process of introducing a cationic group to the surface of the starch by introducing a protonating agent under the conditions.

In the present invention, the protonation agent is one end of the molecule has a reactor capable of binding to hydroxyl groups on the starch molecule, and the other end refers to a substance having a cationic group, and contains a third amino group or a fourth ammonium ether group. Derivatives may be used, and quaternary ammonium-based amphoterics such as 3-chloro-2-hydroxytrimethylammonium chloride and 2,3-epoxypropyltrimethylammonium chloride are preferred.

In the present invention, after the completion of the protonation reaction, the starch slurry may be directly oxidized without dehydration and drying.

In the present invention, the oxidation reaction refers to a process of decomposing the cationic starch produced by the protonation reaction to have a required viscosity level by treating the oxidizing agent. In order to improve the oxidation efficiency, the oxidation reaction may be carried out in the presence of a metal catalyst if necessary.

In the present invention, the oxidizing agent refers to a substance used to oxidize and lower the cationic starch prepared by the protonation process, and peroxides, persulfates, permanganate, and the like may be used, but generally for oxidizing starch. When using a persulfate-based compound such as ammonium persulfate, sodium persulfate, or potassium persulfate, or a substance such as sodium hypochlorite, the final cationic starch has a low degree of cationic substitution and thus a desired surface sizing effect cannot be obtained. It is not suitable for the low viscosity of cationic starch to be achieved in the present invention. In addition, when oxidizing starch using HCl, when compared with hydrogen peroxide, not only the reaction temperature should be high, but also a large amount of input is required, in which case a large amount of salt is formed. Therefore, hydrogen peroxide is preferable as the oxidant in the present invention. The amount of hydrogen peroxide used is 0.5 to 3% (w / w) relative to dried starch.

In the present invention, the metal catalyst refers to a substance to be added to improve the reaction efficiency of the oxidizing agent, and metal salts such as copper, iron, and manganese may be used, for example, copper sulfate, iron sulfate, or the like. The amount of catalyst to be used will vary depending on the amount of starch, the amount of hydrogen peroxide, the type of catalyst, and the like, but may be added at least 0.01% (w / w) with respect to hydrogen peroxide.

The pH of the oxidation reaction is suitable pH 7.5-12, preferably pH 8.5-11. When the reaction pH is low, there is a problem that aging phenomenon occurs because the turbidity of the lake solution is relatively severe during cooling.

When the required level of viscosity is reached, a reaction terminator is added to complete the oxidation reaction. At this time, the reaction terminating agent refers to a substance used to dissipate the reactivity of the oxidizing agent so that no further oxidation reaction occurs after the reaction is completed, and sodium metabisulfite, peroxidase, peroxide scavenging agent, and the like can be used.

Recycling the surface sized phage with the cationic starch of the present invention is less than 20% of the starch eluted in the white water, when using the oxidized starch compared to the eluted in the white water more than 60%, the COD load of the white water Can be reduced by more than 10%.

When the surface-sized phage using cationic starch according to the present invention is used, the retention effect of the fine powder and the filler is about 5% and 15% higher than the starch oxide, respectively. This is because the cationic starch of the present invention has a smaller reduction in the chemical effect of the preservative than the oxidized starch, and causes agglomeration of the stock. Therefore, when the cationic starch is used, the amount of the preservative is reduced compared to the oxidized starch. You can expect

The cationic group substitution degree of the starch in the present invention is measured using a PCD (ParticleCharge Detector; MUTEK, Germany) meter according to the following method.

1) 20 g of sample starch is dipped in 100 ml of 0.1N HCl.

2) After immersion, suction filtration with filter paper for quantitative analysis (5 types B), and sprinkle with 50 ml of 75% methanol three times on the residue on the filter paper and filter again.

3) The residue is dried in an oven at 40 ° C. for 2 hours, after which the sample is pulverized and 3 g is taken to measure the moisture content.

4) Pour 0.1 g of sample and 100 ml of distilled water into the flask. Make a 0.1% solution, place it on a hotplate and warm with stirring.

5) After stirring and cooking at room temperature to 95 ° C., cool to room temperature and add distilled water to make a total of 100 ml of the sample.

6) Take 10 ml of the prepared sample and measure the degree of substitution using a PCD meter.

Starch viscosity in the present invention is measured using a Brookfield viscometer (Brookfied, USA) according to the following method.

1) Measure the moisture of the sample starch.

2) Put 25g of starch (based on dry solids) in 500ml stainless beaker and pour distilled water to make 250g total. Prepare a 10% (w / w) starch solution.

3) After dispersing well, install it on a boiling water bath, adjust and fix the stirrer slightly away from the bottom of the beaker, cover it, and warm it at 100 rpm.

4) Allow the warming time to warm up to 95 ° C from room temperature to about 5 minutes, and cook with stirring at 95 ± 1 ° C for 10 minutes.

5) Cool and weigh in cold water to bring the cooked stock solution to 55 ° C and add distilled water to a total amount of 250 g.

6) Stir the arc solution to 50 ℃, put it in the viscosity measuring container, adjust the viscometer to submerge in the solution to the indicator line of the viscometer spindle, and then rotate the viscometer spindle.

7) When the spindle rotation time is 45 seconds, stop the rotation. Read the value displayed on the viscometer and multiply the number by the Brookfield constant provided by Brookfield Corporation as the viscosity (unit: cps).

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

Example 1 Change in Degree of Substitution with Amount of Protonating Agent

According to condition 1 of Table 1, 1000 g (db) of corn starch was prepared into a concentration 22 boromine slurry, adjusted to pH 11.8, and temperature of 43 ° C., and then the amount of 3-chloro-2-hydroxytrimethylammonium chloride was added to each test group. Differently added and reacted for 12 hours. The degree of substitution was measured according to the input amount of 3-chloro-2-hydroxytrimethylammonium chloride, and the results are shown in Table 2. The degree of substitution increased as the amount of protonating agent increased.

Cationic Starch Preparation Conditions Positive reaction Oxidation reaction Starch (g) ^* pH Positive agent ^** (g) Hours (hr) Temperature (℃) pH Catalyst (g) Hydrogen peroxide ^*** (g) Sodium Bisulfite (g) Hours (hr) Temperature (℃) One 1000 11.8 9.4-37.42 12 43 - - - - - - 2 1000 11.8 18.7 12 43 10.5 0-0.21 42.9 1.5 5.5 43 3 1000 11.8 18.7 12 43 10.5 0.057-0.25 14.3-62.0 1.5 5.5 43 4 1000 11.8 18.7 12 43 7.5-11.5 0.17 / 0.23 42.9 / 57.1 1.5 5.5 43 5 1000 11.8 14.1-42.1 12 43 4.5-5.0 - HHCl2-5% - ^**** 5.5 43 6 1000 11.8 23.4 12 43 9.5 - NaOCl320g 1.5 5.5 43 7 1000 11.8 23.4 12 43 9.5 0.23 57.1 1.5 5.5 43 8 1000 11.8 15.4 / 25.4 / 41.1 12 43 9.5 0.17 / 0.23 57.1 1.5 5.5 43

^* Concentration of raw starch slurry during reaction (22 bome)

^** Based on 100% positive agent

^*** Hydrogen peroxide: 35% aqueous solution

^**** neutralized with NaOH

Degree of substitution according to the amount of protonating agent Input amount (g) Degree of substitution 9.36 0.01 ± 0.001 18.71 0.02 ± 0.002 37.42 0.04 ± 0.003

Example 2 Change of Degree of Substitution and Viscosity of Cationic Starch According to Oxidation Catalyst Addition

Cationic starch was prepared according to the condition 2 in Table 1 below. Corn starch slurry (22 boome) was adjusted to pH 11.8, 43 ° C and then positively reacted with 18.7 g of 2,3-epoxypropyltrimethyl ammonium chloride for 12 hours. When the positive reaction was completed, the copper sulfate as a catalyst was added in varying amounts in the range of 0 to 0.21 g while maintaining the temperature. 42.9 g of hydrogen peroxide (35% aqueous solution) was added thereto and reacted for 5.5 hours while maintaining a pH of 10.5. When the reaction was completed, 1.5 g of sodium bisulfite was added to remove unreacted hydrogen peroxide, and then neutralized by adding hydrochloric acid. The viscosity is measured while changing the temperature of starch, and the result is shown in FIG. The neutralized reaction solution was washed with water using a filtration device, separated, and dried to obtain a cationic starch. Cationic group substitution degree of starch was analyzed. The results are shown in Table 3. The same reaction was carried out using iron sulfate instead of copper sulfate and the degree of cationic group substitution of the starch was analyzed. The results are shown in Table 3. The viscosity was measured while changing the temperature of the prepared starch, and the results are shown in Tables 4 and 5.

Degree of substitution according to starch oxide catalyst capacity (%) Catalyst 0 0.1 0.2 0.3 0.4 0.5 CuSO ₄ - 0.014 0.012 0.012 0.012 0.013 FeSO ₄ 0.018 - 0.014 0.017 0.015 -

Viscosity of Cationic Starch According to Copper Sulfate Input Input amount (%) Measuring temperature (℃) 0 0.1 0.2 0.3 0.4 0.5 30 1500 98 31 25 20 20 40 44 24 23 17 18 50 25 19 21 16 15 60 17 14 15 14 13 70 13 10 10 11 9 80 12 9 9 8 7

Temperature Viscosity of Cationic Starch According to Ferrous Sulfate Input Input amount (%) Measuring temperature (℃) 0 0.2 0.3 0.4 30 1500 28 22 30 40 18 17 22 50 15 15 19 60 12 11 16 70 10 9 13 80 8 8 8

Iron sulfate was more advantageous in terms of substitution than copper sulfate, but was somewhat poor in color and foreign matter of the final product.

Regardless of the type of catalyst, the viscosity of the prepared cationic starch showed a tendency to decrease as the temperature increased and the amount of the catalyst added increased. When comparing the viscosity at 50 ℃ even if the catalyst input is increased to more than 0.2%, the viscosity lowering effect was not large.

Example 3 Change of Degree of Substitution and Viscosity of Cationic Starch According to Addition of Oxidizer

Cationic starch was prepared in the same manner as in Example 2 except for changing the amount of hydrogen peroxide according to Condition 3 of Table 1. The amount of catalyst was added 0.14% (w / w) to hydrogen peroxide. The degree of substitution and viscosity of the prepared starch were analyzed and the results are shown in Table 6.

Substitution degree and viscosity of cationic starch according to the amount of oxidizing agent added input(%) 0.5 1.0 1.5 1.7 2.0 2.2 Degree of substitution 0.019 0.014 0.012 0.011 0.011 0.010 Viscosity (cps) 990 68 18 12 9 9

As the amount of hydrogen peroxide increased, the degree of substitution rapidly decreased, and the viscosity was also greatly reduced, and the effect of viscosity reduction was not significant when hydrogen peroxide was added more than 2.0%.

Example 4. Substitution degree and viscosity change of cationic starch according to oxidation pH

The same method as in Example 2 except that the amount of hydrogen peroxide was 57.1 g (2% (w / w) based on dry starch), the amount of catalyst was 0.23 g according to the condition 4 of Table 1, and the pH of the oxidation reaction was changed. Cationic starch was prepared. The same experiment was carried out with the amount of hydrogen peroxide being 42.9 g (1.5% (w / w) for dry starch) instead of 57.1 g and the catalyst amount being 0.06 g. The degree of substitution and viscosity of the prepared cationic starch were analyzed, and the results are shown in Table 7, respectively.

Degree of substitution and viscosity of cationic starch according to oxidation pH pH 8.5 9.5 10.5 Degree of substitution 0.010 0.013 0.011 Viscosity 12.5 15.5 14.5

Comparative Example 1. Cationic Starch Preparation by Oxidation with HCl

According to condition 5 of Table 1, cationic starch was prepared in the same manner as in Example 2 except for using HCl instead of hydrogen peroxide while varying the amount of protonating agent. No catalyst was added. In other words, 14.1 g of 2,3-epoxypropyltrimethyl ammonium chloride was added to the starch (substitution degree: 0.015), which was protonated, and then oxidized by treating 2-5% (w / w) of hydrochloric acid with dry starch, followed by oxidation of NaOH. The reaction was stopped by addition to produce cationic starch. 2,3-epoxypropyltrimethyl ammonium chloride, an amphoteric agent, was tested in the same manner using 28.1 g (substitution degree: 0.30) and 42.1 g (substitution degree: 0.45). The degree of substitution and viscosity of the prepared cationic starch were analyzed and the results are shown in Tables 8 and 9, respectively. As the amount of hydrochloric acid was increased, the viscosity decreased, but when 4% or more was added, the trend of the positive agent (DS standard) was reversed.

Changes in the Degree of Substitution of Cationic Starch by Temperature and Hydrochloric Acid Amount of protonation agent (g) (degree of substitution after quantization reaction) HCl input (%) 2 3 4 5 14.1 (0.015) 0.012 0.011 0.010 0.010 28.1 (0.030) 0.027 0.026 0.024 0.025 42.1 (0.045) 0.039 0.039 0.037 0.037

Viscosity Variation of Cationic Starch by Temperature and Hydrochloric Acid Amount of protonation agent (g) (degree of substitution after quantization reaction) Temperature (℃) HCl input (%) 2 3 4 5 14.1 (0.015) 30 3400 1120 750 383 40 1600 495 208 185 50 1250 330 87 119 60 1160 295 65 85 70 940 285 43 42 80 300 200 35 30 28.1 (0.030) 30 2800 670 135 91 40 1200 350 100 70 50 950 310 63 52 60 600 293 52 42 70 355 293 30 17 80 315 105 16 13 42.1 (0.045) 30 3000 360 150 70 40 1400 220 130 54 50 900 200 110 45 60 500 185 93 36 70 380 160 53 18 80 350 61 41 15

As the amount of hydrochloric acid increased, the viscosity of the cationic starch decreased, and as the degree of substitution increased, the viscosity decreased. However, when the measurement temperature was set to 50 ° C., the viscosity could not be lowered to 45 cps or lower even when the amount of hydrochloric acid was increased to 5%.

Comparative Example 2 Preparation of Cationic Starch by Oxidation with Sodium Hypochlorite

According to condition 6 of Table 1, cationic starch was prepared in the same manner as in Example 2 except for reacting at pH 9.5 using 320 g of NaOCl instead of hydrogen peroxide. No catalyst was added. In other words, cationic starch was prepared by oxidizing starch reacted with 2,3-epoxypropyltrimethyl ammonium chloride by treating with 320 g of NaOCl (effective chlorine: 12%) and adding sodium bisulfite to stop the reaction. . The degree of substitution of the cationic starch prepared was 0.001 and the viscosity was 15 cps. When NaOCl was used as the oxidizing agent, the viscosity decreased but the degree of substitution decreased rapidly.

Example 5 Influence of Sequence of Protonation and Oxidation

Cationic starch was prepared by the same method as Example 2 (oxidation reaction after a positive reaction) by the condition 7 of Table 1.

Equally, according to condition 2 of Table 1, cationic starch was prepared by performing an oxidation reaction first and then performing a protonation reaction. That is, the corn starch slurry (22 ume) was adjusted to pH 11.8, 43 ° C temperature, and then 0.08 g of copper sulfate as a catalyst was added thereto. 57.1 g of hydrogen peroxide was added thereto and reacted for 5.5 hours while maintaining a pH of 9.5. When the reaction was completed, 1.5 g of sodium bisulfite was added to remove unreacted hydrogen peroxide, and then neutralized by adding hydrochloric acid. 23.4 g of 2,3-epoxypropyltrimethyl ammonium chloride was added thereto, followed by protonation for 12 hours. The degree of substitution and viscosity of the prepared cationic starch were analyzed and the results are shown in Table 10. Oxidation reaction after the positive reaction could maintain the degree of substitution.

Degree of Substitution and Viscosity of Cationic Starch According to Reaction Sequence Item Oxidation reaction after positive reaction Protonation after oxidation Degree of substitution 0.021 0.0055 Viscosity 15.5 13.3

Example 6 Comparison of Properties of Paper Using Cationic Starch and Conventional Starch Oxide

According to condition 8 of Table 1, three cationic starches were prepared by varying the amount of the positive agent to 15.3 g, 25.4 g, and 41.1 g, and the degree of substitution and viscosity were measured. The substitution degree was 0.010, 0.016, 0.03, respectively, and the viscosity was about 12 cps. The physical properties of paper prepared using three cationic starch prepared and conventional oxidized starch (sunsize 3010, Samyang Genex) were compared.

As a pulp, hardwood bleached pulp and conifer bleached pulp beaten to a Yeosu 450mL CSF were used. Cationic polyacrylamide (PAM) was used as a retention agent and calcium carbonate was used as a filler.

First, the starch slurry having a concentration of 10% was gelatinized at 95 ° C. for 30 minutes and stored in a constant temperature water bath having a temperature of 60 ° C. The prepared starch liquor was surface sized on paper using a film coater. Thereafter, the cylinder drier was passed through once, followed by drying the surface of the back surface in the same manner. The pickup amount of both surfaces was set to 4 g / m ² . Surface-sized paper was calcined after constant temperature and humidity treatment to compare the physical properties of the paper. The results are shown in Table 11. The paper surface-sized with cationic starch improved the opacity, ink density and gloss better than paper surface-sized with oxidized starch. Surface sizing of the oxidized starch showed higher tensile strength than that of the cationic starch, but the stiffness was higher in the cationic starch. This means that cationic starch has a higher surface retention than oxidized starch.

Comparison of Properties of Paper Using Cationic Starch and Conventional Starch Oxide Starch Cationic Starch I Cationic Starch II Cationic Starch III Starch oxide Degree of substitution 0.010 0.016 0.030 - Opacity (%) 81.42 80.97 80.49 80.01 Glossiness (%) 8.61 6.80 5.59 5.59 Ink density 1.28 1.26 1.25 1.25 Tensile Strength (Nm / g) 49.8 51.8 Stiffness (nNm) 0.50 0.41

[Pickup volume: 5.5 g / m ² ]

Example 7 Analysis of Surface Residual Differences Between Cationic Starch and Oxidized Starch

Using the confocal scanning microscope (CLSM), the paper sized by the method of Example 6 was observed inside the paper sized by cationic starch and oxidized starch, and the penetration depth of starch was analyzed to confirm the difference in surface residuals of starch. It was.

Cationic starch and oxidized starch stained with acryl orange were surface-sized (pickup amount: 9.2 g / m ² ) on the same paper (basic weight: 159 g / m ² ), respectively, and the penetration depth was photographed by CLSM (FIG. 1 and 2, it was found that the surface residual property is excellent. In addition, the ionic starch film layer had a high density, and the penetration of the ink during printing was reduced, thereby reducing the reflection of the ink.

Example 8 Evaluation of Paper Adsorption Rate between Cationic Starch and Oxidized Starch

In order to evaluate the papermaking efficiency according to the rehabilitation of surface-sized phage, hardwood bleached pulp and conifer bleached pulp beaten with 450 mL CSF were mixed at a ratio of 7: 3. After surface sizing cationic starch or oxidized starch so that the amount of double-sided pickup is constant on the base paper (Basic weight 75 g / m ² ), the dissociated paper is dissociated using a dissociator at a concentration of 2% and a temperature of 40 ° C. The pulp prepared above was mixed at a ratio of 7: 3, stirred at 40 ° C. for 60 minutes, and the amount of starch eluted into the water of the stock was measured spectroscopically.

In the case of recycling surface-sized phage with cationic starch and oxidized starch, the ratio of starch eluted in white water is measured and shown in FIG. 3. In addition, the resulting COD load of white water is measured and shown in FIG. 4. Starch oxide was eluted over 60% in white water, but cationic starch was less than 20%.

Example 8 Comparison of Fine and Fill Retention Characteristics of Cationic Starch and Oxidized Starch

Into the stock formed by the method of Example 7, 15%, 20%, and 25% of a filler was added, and 0.03% of a retention agent was added. The surface of the paper sized by the method of Example 6 was measured in DDJ (Dynamic Drainage Jar; Poonglim Co., Korea) to measure the fine powder and the filler retention degree, and are shown in FIG. 5. When surface-sized phages were used with cationic starch, it was confirmed that the retention effect of fines and fillers was 5% and 15% higher than starch oxide.

Cationic starch according to the present invention, when used for paper surface sizing, less penetrating into the paper, thereby improving the surface strength opacity and printability, and the amount of starch eluted during waste paper recycling reduced the anionic trace of the paper system Since the load can be lowered, the COD load can be lowered.

Claims (3)

(correction) After cationic starch is reacted to produce cationic starch, A method of producing a cationic starch for paper surface sizing, which comprises oxidizing the cationic starch under pH 7.5 to 12.0 using hydrogen peroxide as an oxidizing agent. The method according to claim 1, wherein the hydrogen peroxide is used in an amount of 0.5 to 3% (w / w) based on dry starch. The method of claim 1, wherein the oxidation reaction is carried out in the presence of a metal catalyst.