JPH04363301A - Modified starch, its producton and papermakers sizing agent using the samie agent - Google Patents

Abstract

PURPOSE:To provide a modified starch excellent in stabilization of emulsion for a reactive sizing agent and capable of providing a sizing agent remarkably excellent in sizing effect by addition to a sizing agent for papermaking of neutral paper as a dispersant. CONSTITUTION:A modified starch of formula I(St is starch; R1 is H or CH3; R2 is CH3, C2H5, etc.; R3 is formula II, III, etc.; X<-> is anion). The above- mentioned starch can be obtained by reacting starch with a compound of formula IV [Y is formula V or VI (M is halogen)] in the presence of an alkaline catalyst preferably at >=30 deg.C and >=PH 11. As the cationizing agent of formula IV, e.g. 3-chloro-2-hydroxypropyltriphenylammonium chloride is exemplified.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a novel modified starch and a neutral paper sizing agent using the same, and more particularly to a neutral paper sizing agent having good emulsion stability.

0002

BACKGROUND OF THE INVENTION Neutral paper sizes are becoming established in the paper industry. The use of neutral sizing agents is not only desirable in that it increases the durability of the paper, but is also economically advantageous. In other words, rosin-based sizing agents are used in acidic papermaking using sulfuric acid bands together with petroleum resin sizing agents, but in acidic papermaking systems, cheap calcium carbonate as filler decomposes and foams, so they cannot be used, but in neutral papermaking systems, rosin-based sizing agents cannot be used. Can be used. It is said that high filling can reduce the amount of fiber raw materials.
Benefits include preventing machinery from rusting. Neutral paper-making sizing agents include reactive sizing agents that react directly with cellulose. Representative examples of these include alkenyl succinic anhydride, alkyl ketene dimer, alkyl ketene dimer derivative, isocyanate aziridine derivative, succinimide derivative, rosin anhydride, carbonyl derivative, fatty acid anhydride, and the like. The use of cationized starch as a dispersing agent when dispersing these reactive sizing agents in water to obtain an aqueous emulsifier has been proposed in Japanese Patent Publication No. 39-1989.
This method is disclosed in Japanese Patent Application Laid-open No. 2305 and Japanese Patent Application Laid-open No. 197397/1983.

0003

[Problems to be Solved by the Invention] In conventionally used cationized starch, the number of carbon atoms of the alkyl group bonded to the nitrogen atom of the amino group that exhibits cationic properties is short, 1 to 3, so that the reaction is difficult. However, there is a problem in that sufficient emulsion stability cannot be obtained with respect to the sizing agent.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have conducted intensive research and found that a phenyl group and a benzyl group are added to the nitrogen atom of the amino group that expresses the cationic properties of cationized starch. The present inventors have discovered that emulsion stability against reactive sizing agents can be improved by bonding groups and/or cyclohexyl groups, and have completed the present invention. That is, since the cationically modified starch represented by Chemical Formula 4 has a large hydrophobic group, it exhibits strong emulsifying properties due to the inherent hydrophilicity of starch. Therefore, a dispersion of the reactive sizing agent with good emulsion stability can be obtained.

[C4]

The cationizing agent that can be used in the present invention is represented by the following formula. Examples of the compound represented by Chemical Formula 5 include 3-chloro-2-hydroxypropyltriphenylammonium chloride, 3-chloro-2-hydroxypropyltribenzylammonium chloride, 3-chloro-2-hydroxypropyltriphenylammonium chloride,
Chloro-2-hydroxypropyltricyclohexylammonium chloride, 3-chloro-2-hydroxypropyldiphenylmethylammonium chloride, 3-
Chloro-2-hydroxypropyldibenzylmethylammonium chloride, 3-chloro-2-hydroxypropyldicyclohexylmethylammonium chloride,
3-chloro-2-hydroxypropyldiphenylethylammonium chloride, 3-chloro-2-hydroxypropyldibenzylethylammonium chloride, 3
-Chloro-2-hydroxypropyldicyclohexylethylammonium chloride, 3-chloro-2-hydroxypropyldimethylphenylammonium chloride, 3-chloro-2-hydroxypropyldiethylphenylammonium chloride, 3-chloro-2-hydroxypropyldimethylbenzylammonium chloride ,
3-chloro-2-hydroxypropyldiethylbenzylammonium chloride, 3-chloro-2-hydroxypropyldimethylcyclohexylammonium chloride, 3-chloro-2-hydroxypropyldiethylammonium chloride, 2,3-epoxypropyltriphenylammonium chloride, 2 , 3-Epoxypropyltribenzyl ammonium chloride, 2,3-epoxypropyltricyclohexylammonium chloride, 2,3-epoxypropyldiphenylmethylammonium chloride, 2,3-epoxypropyldibenzylmethylammonium chloride, 2,3-epoxypropyl Dicyclohexylmethylammonium chloride, 2,3-epoxypropyldiphenylethylammonium chloride, 2,3-epoxypropyldibenzylethylammonium chloride, 2,3-epoxypropyldicyclohexylethylammonium chloride, 2,3-epoxypropyldimethylphenylammonium Chloride, 2,3-epoxypropyldiethylphenylammonium chloride, 2,3-epoxypropyldimethylbenzylammonium chloride, 2,3
- Quaternary ammonium salts such as epoxypropyldiethylbenzylammonium chloride, 2,3-epoxypropyldimethylcyclohexylammonium chloride, 2,3-epoxypropyldiethylcyclohexylammonium chloride, 3-chloro-2-hydroxypropyldiphenylaminochloride, 3- Chloro-2-hydroxypropyldibenzylaminochloride, 3-chloro-2-hydroxypropyldicyclohexylaminochloride, 3-chloro-2-hydroxypropylmethylphenylaminochloride, 3-chloro-2-hydroxypropylmethylbenzylaminochloride, 3 -Chloro-2-hydroxypropylmethylcyclohexylaminochloride, 3-chloro-2-hydroxypropylethylphenylaminochloride, 3-chloro-2-hydroxypropylethylbenzylaminochloride, 3
-Chloro-2-hydroxypropylethylcyclohexylaminochloride, 2,3-epoxypropyldiphenylaminochloride, 2,3-epoxypropyldibenzylaminochloride, 2,3-epoxypropyldicyclohexylaminochloride, 2,3-epoxypropylmethyl Phenylaminochloride, 2,3-epoxypropylmethylbenzylaminochloride, 2,3
- Tertiary amine salts such as epoxypropylmethylcyclohexylaminochloride, 2,3-epoxypropylethylphenylaminochloride, 2,3-epoxypropylethylbenzylaminochloride, 2,3-epoxypropylethylcyclohexylaminochloride, etc. .

[0006] Starch raw materials that can be used in the present invention include:
For example, unprocessed starches such as wheat starch, potato starch, corn starch, sweet potato starch, tapioca starch, sago starch, rice starch, waxy corn starch, high amylose content corn starch, or their etherification, esterification, oxidation, acid Also included are those that have been processed.

The method of cationizing the cationically modified starch of the present invention is carried out in the same manner as the reaction of a conventional cationizing agent. That is, the reaction is carried out by dropping the above cationizing agent into a starch suspension in the presence of an alkali catalyst. The reaction temperature is below the gelatinization start temperature of starch, preferably above 30°C, and at a pH of above 10.5, preferably above pH 11. If necessary, the reaction may be carried out in the presence of an appropriate amount of sodium sulfate. After the reaction, the modified starch of the present invention can be obtained by washing with water, dehydrating, and drying by a known method. The reaction can also be carried out by mixing the above cationizing agent and starch at a moisture content of 2 to 50% and heating in the presence of an alkali catalyst using a suitable mixing or kneading device.

The degree of cationization is expressed as the degree of substitution (DS mole of substituent per mole of anhydroglucose residue). S. =0.01-0.2, preferably 0.01
5 to 0.07 is good. The gelatinization start temperature is preferably 20 to 70°C. Here, the gelatinization start temperature is 15% (W/V) of starch.
Add 450 g of water suspension to Amylograph (brabender two-blade paddle type, measuring head: 700 cm),
It refers to the temperature that rises from the base line of the amylograph when subjected to rotation speed: 75 rpm, temperature rise: 1.5° C./min). The cationically modified starch is required to have high stability of the size liquid. The cationization described above also provides considerable stability, but when a more stable size solution is required,
It is necessary to partially substitute nonionic functional groups by cationizing and etherifying and/or esterifying the hydroxyl group of glucose. It was also found that this treatment increased emulsion stability and paper strength. Etherification and esterification of starch are carried out according to conventional methods. For example, starch methyl ether reacted with dimethyl sulfate or methyl iodide, starch allyl ether reacted with allyl chloride, and starch reacted with acrylonitrile are used as etherified starch. starch cyanoethyl ether, starch carbamoylethyl ether reacted with acrylamide, starch hydroxyethyl ether reacted with ethylene oxide, starch hydroxypropyl ether reacted with propylene oxide, starch hydroxybutyl ether reacted with butylene oxide, etc. In addition, as esterified starch, starch formate ester, starch propionate ester, starch laurate ester, starch myristic ester reacted with fatty acids such as formic acid, propionic acid, lauric acid, myristic acid, palmitic acid, stearic acid, etc. , starch palmitate, starch stearate, starch acetate reacted with acetic anhydride or vinyl acetate, and the like. Through these processes,
Starch that is partially nonionized by cationization and etherification and/or esterification has improved stability and a lower gelatinization initiation temperature. Its gelatinization initiation temperature is 20-70°C, preferably 30-55°C.

[0009] Furthermore, in order to make the neutral size emulsion for papermaking highly concentrated, the cationic starch derivative must be reduced in molecular weight. Methods for reducing the molecular weight include acid hydrolysis using mineral acids, oxidation and molecular cleavage using oxidizing agents, oxygen decomposition using starch-degrading enzymes, and physical decomposition using heat, ultrasound, radiation, etc. Examples include methods of cutting molecules. The molecular weight at this time is 5,000 to 50,000, preferably 8,000 to 50,000.
30,000, and the viscosity is 10 to 1,000 centipoise when a 20% by weight aqueous suspension is gelatinized by heating in a water bath above 85°C for 10 minutes, cooled to 30°C, and measured with a B-type rotational viscometer.
Preferably it is 20 to 700 centipoise.

The paper sizing agent of the present invention is obtained by adding 10 to 150% of a cationic starch derivative as an emulsion stabilizer to the active ingredient of the reactive sizing agent as the main component and emulsifying the active ingredient. . Examples of the reactive sizing agent suitably used in the present invention include alkenyl succinic anhydride, alkyl ketene dimer, alkyl ketene dimer derivatives, and stearic anhydride. The concentration of the neutral papermaking size emulsion of the present invention is 5 to 60%, preferably 10 to 40%. The neutral paper sizing agent of the present invention may contain surfactants such as sodium ligninsulfonate and polyoxyethylene lauric acid amide, and water-soluble polymers such as polyvinyl alcohol and acrylamide polymers, if necessary. . The sizing agent thus obtained can be used as an internal sizing agent by adding it to the pulp slurry, or as a surface sizing agent by adding it to the sheet surface.

[0011]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 130 parts of water, 2 parts of sodium hydroxide, 5 parts of sodium sulfate
Add 100 parts of tapioca starch to 0 parts, then add 13 parts of 3-chloro-2-hydroxypropyldimethylbenzyl ammonium chloride (40% aqueous solution), and add 100 parts of tapioca starch to 0 parts.
Time reacts. After 5 hours, 3 parts of propylene oxide was added and reacted at 40°C for 6 hours. After the reaction is complete, lower the temperature to 30°C and add sodium hypochlorite (available chlorine amount: 14%).
Add 30 parts and react for 1 hour. After the reaction is complete, purge with dilute hydrochloric acid.
The starch was neutralized to H4.5, dehydrated, washed with water, and dried to obtain a cationically modified starch. Degree of substitution of cationic groups in the obtained starch (D.
S. )=0.03, gelatinization start temperature 49℃, viscosity 20%
, 42 centipoise at 30°C.

Example 2 In Example 1, tapioca starch was mixed with cornstarch.
A cationically modified starch was obtained in the same manner as in Example 1 except that 2,3-epoxypropyldiphenylmethylammonium chloride was used instead of chloro-2-hydroxypropyldimethylbenzylammonium chloride. The resulting starch had a degree of substitution (D.S.) of cationic groups of 0.03, a gelatinization initiation temperature of 50°C, a viscosity of 20%, and 48 centipoise at 30°C. Example 3 A cation was prepared in the same manner as in Example 1 except that in Example 1, tapioca flour was replaced with potato starch and 3-chloro-2-hydroxypropyldimethylbenzylammonium chloride was replaced with 3-chloro-2-hydroxypropyldimethylcyclohexylammonium chloride. Modified starch was obtained. Degree of substitution (D.S.) of cationic groups in the obtained starch = 0
．． 025, gelatinization start temperature 49℃, viscosity 20%, 30℃
It was 46 centipoise. Example 4 100 parts of tapioca starch is added to a solution of 130 parts of water, 1.8 parts of sodium hydroxide, and 50 parts of sodium sulfate, 8 parts of acrylonitrile are added, and the mixture is reacted at 40° C. for 8 hours. Next, 10 parts of 3-chloro-2-hydroxypropyltribenzyl ammonium chloride is added, and the mixture is reacted at 40° C. for 6 hours while maintaining the pH at 11.5 with 3% sodium hydroxide. 18 parts of 35% hydrogen peroxide solution was added to this and reacted for 4 hours. After the reaction was completed, the mixture was neutralized to pH 4.5 with diluted hydrochloric acid, dehydrated, washed with water, and dried to obtain cationically modified starch. The resulting starch had a degree of substitution (D.S.) of cationic groups of 0.02, a gelatinization initiation temperature of 50°C, a viscosity of 20%, and a viscosity of 100 centipoise at 30°C. Example 5 A mixed solution of 8 parts of water, 8.2 parts of methanol, and 2 parts of 50% sodium hydroxide is added to 100 parts of cornstarch, and after dispersion, 10 parts of ethylene oxide is added and reacted at 38° C. for 10 hours. After 10 hours, the reactant was poured into 120 parts of water, the temperature was raised to 43°C, and 8 parts of 3-chloro-2-hydroxypropyltriphenylammonium chloride was added.
5 while maintaining pH 11 with 3% sodium hydroxide aqueous solution.
Time reacts. After the reaction, lower the pH to 5 with dilute hydrochloric acid to 20%.
After adding 18 parts of hydrochloric acid and reacting at 40°C for 15 hours, 3
% sodium hydroxide aqueous solution to pH 4.5, dehydrated, washed with water, and dried to obtain a cationically modified starch. The resulting starch had a degree of substitution (D.S.) of cationic groups of 0.02, a gelatinization initiation temperature of 49°C, and a viscosity of 20% and 80 centipoise at 30°C. Example 6 100 parts of oxidized starch was added to 130 parts of water, 1.5 parts of sodium hydroxide, and 50 parts of sodium sulfate, then 10 parts of 2,3-epoxypropyldibenzylaminochloride was added, and 3% sodium hydroxide was added. The reaction was carried out at 40° C. for 5 hours while maintaining the pH at 11.2 with an aqueous solution. The reaction solution was lowered to 30°C, and after adjusting the pH to 8 to 9 with dilute hydrochloric acid, 6 parts of vinyl acetate was added, and the mixture was reacted at 30°C and pH 8 to 9 for 10 hours. After the reaction was completed, the mixture was neutralized to pH 4.5 with diluted hydrochloric acid, dehydrated, washed with water, and dried to obtain cationically modified starch. Degree of substitution (D.S.) of cationic groups in the obtained starch = 0.04, gelatinization initiation temperature 46
The viscosity was 20% and 60 centipoise at 30°C.

Comparative Example 1 Cationically modified starch was obtained in the same manner as in Example 1 except that 3-chloro-2-hydroxypropyldimethylbenzylammonium chloride was replaced with 3-chloro-2-hydroxypropyltrimethylammonium chloride. Ta. Degree of substitution of cationic groups (D
．． S. )=0.04, gelatinization start temperature 48℃, viscosity 20
%, 90 centipoise at 30°C. Comparative Example 2 Cationically modified starch was obtained in the same manner as in Example 1 except that 2-diethylaminoethyl chloride was used instead of 3-chloro-2-hydroxypropyldimethylbenzyl ammonium chloride. The resulting starch had a degree of substitution (D.S.) of cationic groups of 0.05, a gelatinization initiation temperature of 45°C, a viscosity of 20%, and 80 centipoise at 30°C.

Example 7 24 parts of dodecenyl succinic anhydride, 30 parts of the 20% aqueous solution of the cationically modified starch obtained in Examples 1 to 6 and Comparative Examples 1 to 2, and 146 parts of ion-exchanged water were heated to 80°C. The mixture was preliminarily dispersed in a homomixer, passed through a homogenizer twice while maintaining the same temperature, and after cooling was filtered through a 350 mesh sieve to obtain an aqueous emulsion. The resulting aqueous emulsion was transferred to a 100 ml graduated cylinder and left at room temperature. A storage stability test was conducted based on changes in the volume (ml) of the emulsified layer over time. In addition, a blank sample to which cationically modified starch was not added was also tested in the same manner. The results are shown in Table 1.

[Table 1] Example 7 Beaten pulp slurry (LBKP, 400 c.s.f.
) was added in an amount equivalent to 3% by weight of the sizing agent prepared in Example 7 based on the weight of the air-dried pulp, and the sizing agent was added to the sizing agent prepared in Example 7 in an amount equivalent to 3% by weight of the air-dried pulp. Using this method, handmade paper with a basis weight of 60 g/m2 was prepared, and the Steckcht sizing test was performed to determine storage stability, and the results shown in Table 2 were obtained.

[Table 2]

Example 9 An aqueous emulsion was obtained in the same manner as in Example 7, except that stearyl ketene dimer was used instead of dodecenyl succinic anhydride, and a storage stability test was conducted. The results are shown in Table 3. Ta.

[Table 3] Example 10 Using the sizing agent prepared in Example 9, a Stekicht sizing test was conducted in the same manner as in Example 8, and the results are shown in Table 4.

[Table 4]

[0016]

[Effects of the Invention] As can be seen from Tables 1 to 4, the sizing agent of the present invention has higher emulsion stability and higher sizing degree than conventional products, and the sizing agent does not decrease in sizing degree due to changes over time like conventional products. Since it is not noticeable, it has extremely high practical value.

[C5]

Claims (5)

[Claims] Claim 1: A modified starch represented by formula 1. [Chemical formula 1] 2. Degree of substitution (D) of cationization of the modified starch
．． S. ) is 0.01 to 0.2 and its average molecular weight is 500
Claim 1: The viscosity of the paste liquid at 30°C is 10 to 1000 centipoise in a 20% aqueous solution.
Modified starch as described. 3. A method for producing modified starch, which comprises reacting starch with a compound represented by Chemical Formula 2 using an alkali catalyst. [Case 2] 4. A method for paper manufacturing, characterized in that the modified starch represented by formula 3 is added to a neutral paper sizing agent selected from alkenyl succinic anhydride, alkyl ketene dimer, alkyl ketene dimer derivative, and stearic anhydride. Sizing agent. [Chemical formula 3] 5. A glue in which the modified starch has a cationization degree (D.S.) of 0.01 to 0.2 and is partially nonionized by etherification and/or esterification. The starting temperature is 20 to 70°C, the average molecular weight is 5000 to 50000, and the viscosity of the paste at 30°C is 20.
4. The paper sizing agent according to claim 3, which has a sizing agent of 10 to 1000 centipoise in an aqueous solution.