KR100226154B1 - Method of preparing highly substituted cationic starch - Google Patents

Abstract

The present invention relates to a method for producing a high-substituted cationic starch, the starch is added to the mixer and continuously mixed in a fluidized bed state, 3-Chloro-2-hydroxypropylammonium chloride or epoxy Atomizing agents such as propyl ammonium chloride (Epoxyprl-ammonium chloride) is finely sprayed, in this case, for uniform spraying of the amphoteric agent, pressurizing the amphoteric solution to 2: 1 using a quantitative compression pump and then nozzle Starch and contact area were maximized by letting it pass through. At the moment when the protonated chemical is adsorbed on the starch, strong shearing force is applied to prevent the formation of lumps (Flock). As shown in Fig. 2, the vortex is continuously vortexed so that the diffusion of the chemical penetrates from the surface of the starch. It provides a method of producing high-substituted cationic starch.

Cationic starch production method according to the present invention is a highly useful method industrially because the reaction yield is higher than the conventional method, the degree of substitution is high, and the manufacturing process is simple.

Description

Method for preparing high substituted cationic starch

The present invention relates to a method for producing high-substituted cationic starch, and more particularly to a method for preparing cationic starch used in the papermaking process.

Cationic starch is one of the most important modified starches in the papermaking industry, and the demand is expected to increase at a very rapid rate due to the introduction of neutral primary in the papermaking process. Therefore, it is necessary to hurry to develop and apply in Korea, but in Korea, it is not only producing positive starch in oxidized starch facilities due to lack of production facilities or relying on imports. It was of poor quality to replace potato starch.

There are many literatures on the preparation of cationic starch, and as it is actively used in the paper industry, it is generalized so that it is not necessary to mention the application technology thereof.

In other words, cationic starch is formed by chemical reaction of starch with chemicals including amino group, imino group, ammonium sulfonate, phosphate group, etc., which have positive charge. Is made. Currently, commercially important derivatives are tertiary amino starch ethers and quaternary ammonium starch ethers. An important factor in using positive starch is the affinity for the negatively charged material. In papermaking, fibrin and cationic starch increase the fiber strength by increasing fiber bonding due to the combination of ionic and hydrogen bonding. It can be combined with other other treatments such as acid hydrolysis, oxidation, dextrinization and the protonation reaction to obtain various viscosities. In addition, neutral and anionic groups are used to balance dispersibility and charge. Drugs used to prepare these cationic starches are mainly (4-chlorobutene-2) -trimethylammonium chloride] and 2-diethylaminoethyl chloride. And 2,3- (epoxylpropyl) trimethyl ammonium chloride].

The cationic starch is electrostatically positive when completely dissolved in water, and the cationicity acts as a negative charge and electrostatic attraction of the filler and the pulp. Therefore, it has the effect of coagulation with each other and improves the workability by improving the dehydration and the degree of freedom in paper manufacturing. The raw materials of the electrostatically bonded paper again bind firmly to the cellulose during the drying process, thereby increasing the paper strength, thereby serving as a dry strength enhancer.

Cationic starch is added to the insufficient quality of general starch, and the ion starch performance is determined by the starch's molecular weight, molecular structure, and binding compound. These cationic capacities can be confirmed in many ways, but the most practical method is to quantitatively analyze the nitrogen content of cationic starch. This can be analyzed by the usual Kjeldahl method, where nitrogen content and electrostatic forces have a constant proportionality. In addition, the degree of substitution (DS) of the starch molecule is calculated with the nitrogen content (%). The theoretical degree of substitution is 3.0 when all the functional groups that can be substituted in the starch are denatured. Will be

However, the reaction starch of substitution degree 3.0 is not practically prepared, and the degree of substitution distributed industrially is usually about 0.03 in consideration of reaction efficiency. (Table 2) In this way, increasing the degree of substitution means, in other words, increasing the electrostatic attraction to the original starch, and is directly related to the efficacy of starch when starch is used in the paper industry. Therefore, it is known how to positively starch through the substitution reaction using the know-how of the positive starch method, and many studies have been conducted for this.

However, domestic technology still lacks the manufacturing technology of cationic starch, so most of the cationic starch is dependent on imports, and the degree of substitution itself remains at a low degree of substitution. By adopting the same innovative method, cost reduction and product quality are always required. In addition, wastewater in the papermaking process is linked with environmental issues, and each company is showing efforts to reduce the discharge of wastewater. As such, two dry processes have been known as a method of producing positive starch to reduce the amount of wastewater. In other words, both DOW (USA) and Degussa (Germany) use a mixer, add an alkali catalyst to the starch powder, and then activate the starch to spray the protonating agent. Such a dry method has the advantages of no wastewater treatment cost, short reaction time, mass production, and cost reduction effect, but has some disadvantages in use. First, DOW's method uses 3-chloro-2-hydroxypropyltrimethylammonium chloride modified with 2, 3-epoxypropyltrimethylammonium chloride by adding sodium hydroxide (NaOH) to make moisture control difficult and NaCl is generated during chemical modification. Therefore, there is a disadvantage that additional processes are required and waste disposal costs are incurred. Degussa's method uses 2,3-epoxypropyltrimethylammonium chloride, so the cost of the drug is high and economical. Also, because it is an epoxide type, it is unstable, so the purity of the drug tends to be lowered, resulting in large storage difficulties and reaction efficiency. It is also moderate compared to other dryers.

Western advanced technology uses neutral papermaking method in papermaking method because it is advantageous for long-term and environmental preservation of paper. As a result, even in our country, it is difficult to introduce the neutral papermaking method in order to improve the quality of paper and to rationalize the process in order to meet the demands of the times. It is a setting that must be applied in connection with the development of technology to reduce the amount of waste water and to increase the retention by using.

Accordingly, it is an object of the present invention to provide a method for producing a cationic starch with high yield and high degree of substitution.

For this purpose, the present inventors completely escape from the current method of modifying by adding a chemical in a starch milk (slurry) state in the same form as the conventional oxidized starch, and reacting the starch as it is in a dry powder state to produce a positive starch. The dry manufacturing method of cationic starch according to the present invention solves the problems of the conventional dry manufacturing method to enable mass production of products with high reaction efficiency, and can solve energy saving and wastewater problems at once. It also has the advantage of lowering the cost of the product.

That is, the present invention has a satisfactory result as a result of the production of the improved cationic starch production method as shown in FIG. 1 with the following experimental facilities for producing uniform cationic starch by the dry manufacturing method. That is, starch is continuously mixed in a fluidized bed in a mixer (3-Chloro-2-hydrozypropylammonium chloride) or epoxypropyl-ammounium cloride. In order to atomize the protonating agent of fine, at this time, for uniform spraying of the protonating agent, pressurizing the protonating agent solution to 2: 1 using a fixed-quantity compression pump, and then scattering by passing through a nozzle to contact the starch and the contact area. It was made to the maximum. At the moment when the protonated chemical is adsorbed on the starch, strong shearing force is applied to prevent the formation of lumps (Flock). As shown in Fig. 2, the vortex is continuously vortexed so that the diffusion of the chemical penetrates from the surface of the starch. It was made.

The starch that can be used in the present invention may be any starch such as corn starch, wheat starch, potato starch, tapioca starch, rice starch, or ether (Ether) by replacing hydroxyl groups in the glucose molecule for modification of these starch bodies. ), Derived starch or crosslinked starch in ester form may be used. The starch may also be a polymer monomer, ie CH ₂ = CH-X, where X is one of the hydrophobic -CN, -CO ₂ R (eg acrylonitrile) or -CO ₂ H, -CONH ₃ , -CO (CH ₂ ) One form of _n , -N + RCl- (eg acrylic acid). Starch grafted using one of the polymers may be used.

Fig. 1 Flowchart for preparing positive starch

2 Structure of Starch Mixer (Mixer) and Movement of Starch

In order to maximize the reaction efficiency, a mixer (mixer) was prepared as follows.

Mixer materials, finishing and shape

All parts in contact with the starch are treated with stainless steel, and the inner surface is ideally finished with SUS 320 grade, which prevents high humidity products from sticking to the inner wall. During the reaction, the starch becomes sticky. It is designed with inverted solid shape (▼) (D angle of 15 ° or more) and adjusts the ratio of B: C to prevent the starch from sticking to the inner wall in the mixer. And complete discharge was achieved after the reaction was completed.

2. Mixer Size

The degree of reaction was found to be very affected by the mixer size. Therefore, it was important to determine the appropriate amount of starch suitable for the propeller agitation capacity. The capacity used in the experiment was 600L, and it was most ideal to carry out the reaction after filling with less than 40% of the total volume with starch, but less than 20% When it fell down to the mixing effect was found to fall.

3. Main blade drive of the mixer

Two speeds were used to adjust the revolutions per minute to 60 rpm and 120 rpm, and a power of 22 Kw motor was used for the rotation. The power of the mixer was very sufficient compared to the size. During the reaction, the temperature of the product further increased (from 55 to 55 ℃), resulting in a very high reaction efficiency of over 95%. In general, the speed of the main wing is preferably about 5-10 m / sec, and the results of the experiments of various types of wings showed no difference in reaction efficiency.

4. Cross screw driver

Cross screw drives were very important in the spraying of chemicals.

In order to prepare uniform positive starch, strong shear force was required at the point where the positive agent was injected, and using a single cross screw resulted in a good result of increasing the reaction efficiency by about 50% than when not used. Chopper's position was most effective when Chopper's wing and main wing were installed to maintain 2-3mm gap. The number of revolutions per minute was 1700rpm, and a motor with a capacity of 7.7Kw was used to rotate it.

5. Exhaust air

Internal air in the mixer is replaced during supply and discharge. Care was taken to ensure that the exhaust air was properly filtered.

Hereinafter, the present invention will be described in detail by way of examples, but is not limited thereto.

Example 1

end. Preparation of Positive Ingredient

100 kg of corn starch is injected into the reaction mixer (mixer), 5.39 kg of sodium hydroxide is added and the initial mixing is stirred for about 5 minutes at 20 m / sec of the main blade speed. Spray the prepared amphoteric agent evenly over 5 minutes and then stir the mixer for 10 minutes at the reaction temperature of 15-40 ℃. After the reaction, the nitrogen content was quantified to obtain a positive starch having a degree of substitution (D.S) of 0.079.

I. Reaction efficiency analysis

20 g of positive starch is slurried in 200 ml of 50% ethanol. The slurry is stirred for 30 minutes and then filtered through Whatman® 6 filter paper. The starch cake was reslurried with 200 ml ethanol (50%) and then stirred for another 10 minutes to repeat the filtration process twice. After drying for 3 hours in a vacuum oven at 130 ℃, the dried samples are stored in a sealable bottle, the reaction efficiency is calculated as follows.

The following table shows the reaction efficiency analysis according to the degree of substitution.

Example 2

100 kg of potato starch cross-linked with 0.01% epichlorohydrin of starch was poured into the reaction mixer, followed by 8.89 kg of calcium hydroxide [Ca (OH) ₂ ] and 1.0 kg of clay. The initial mixing is stirred for about 5 minutes at the main blade speed of 30 m / sec. 23.56 kg of the cationizing agent (3-chloro-2-hydroxypropyltrimethylammonium chloride) prepared while stirring the side chopper installed at the side of the mixer at RPM 1700 was evenly sprayed for about 5 minutes and then the mixer was stirred at a reaction temperature of 15-40 ° C. Stir for 10 minutes. After the reaction, the nitrogen content was quantified to obtain a positive starch having a degree of substitution (DS) of 0.147.

Example 3

Inject 100 kg of tapioca starch into the reaction mixer (mixer), add 6.39 kg of sodium hydroxide, and stir for about 5 minutes at an initial mixing speed of 20 m / sec. 15.71 kg of the prepared amphoteric and 5.4 kg of water are quantitatively added and sprayed evenly over a total of 5 minutes, followed by stirring the mixer for 10 minutes. After the reaction, the nitrogen content was quantified to obtain a positive starch having a degree of substitution (D.S) of 0.098.

Comparative Example 1

Wet Porcess

Prepare 19Be 'of starch liquor (slurry) and add 3L of starch slurry to the reaction tube (5L).

After adjusting to pH 12-13 with sodium hydroxide (4%), 40 g of a cationic agent (3-Chloro-2-Hydroxypropyltri-methylammonium chloride) was added quantitatively and reacted for 4-5 hours. After completion of the reaction, neutralized to pH 5.6 with hydrochloric acid (15%), filtered, washed with water and dried, and the degree of substitution (DS) was 0.035 by nitrogen quantification.

Comparative Example 2

DOW Dry Process

Modification of 3-chloro-2-hydroxypropyltrimethylammonium chloride

3-chloro-2-hydroxypropyltrimethylammonium chloride (7.2575 g, 63.75%) is placed in a glass beaker and 6.5 ml of sodium hydroxide (3.88N) is added and stirred automatically for 10 minutes. During migration, CHPTMAT is transformed into 2,3-epoxypropyltrimethylammonium chloride.

After completion of the epoxide form, add 93.48 g of potato starch to the mixer, and mix with 5.6 g of calcium oxide (CaO) and 7.8 g of kaolin. During mixing, spray the epoxide type amphoteric over 10 minutes and then mix for 20 more minutes. Substitution degree (DS) is 0.043, and reaction efficiency (%) is 84%.

Comparative Example 3

Degussa Dry Process

1 kg of corn starch (12% water) was added to the mixer, and 23.8 g of catalyst (PC2 / 9F: a mixture of calcium hydroxide and silica) was stirred. Then, 90.2 g of 2,3-epoxypropyltrimethylammonium chloride (71% purity) was added thereto. After spraying and mixing for 15 minutes, a cationic starch having a degree of substitution (DS) of 0.08 reaction efficiency of 85% can be obtained.

As described above, the dry method according to the method of the present invention is characterized in that the reaction yield (Yield) is much higher than the conventional wet method as shown in Tables 1 and 2, and the degree of substitution, which is the degree of reaction of the positive starch when prepared by the dry method. (DS) can be raised to levels (0.2 to 0.5) that were not achievable in conventional processes. This is the positive factor of positive starch when making paper using positive starch in papermaking process, which increases the retention of fillers (e.g. calcium carbonate) during the process, which not only reduces paper cost but also improves opacity and prints. It will be a very important development considering the effect of improving aptitude, improving surface strength, etc.

TABLE 1

Comparison of Reaction Efficiency (%) between Conventional Wet and Dry Methods

TABLE 2

Maximum Possible Substitution (D.S) Comparison

In addition, the conventional wet method produces a positive starch by adding a reactant to the starch milk to make the starch positive, and washes, dehydrates and dries to prepare the positive starch powder. Simple is characterized. In other words, there is no solvent or water in the process, so there is no separate dehydration or drying process, so the total manufacturing time is shortened and no additional waste water is generated. 3). In addition, the reaction yield is very high compared to continuous denatured modification, it is possible to manufacture high-quality cationic starch, and it is very useful industrially because it has the advantage of obtaining a uniform product.

TABLE 3

Comparison with existing recipe

Claims (6)

In preparing cationic starch, the starch is mixed in a fluidized bed in a mixer, and sprayed with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMAC) with a cationic agent in a dry powder state. Degree of substitution (DS; degree of substitution) A method for producing a highly substituted positive starch, characterized in that to prepare a positive starch of 0.02 ~ 0.3. The method for producing highly substituted cationic starch according to claim 1, wherein water is used as a solvent or less than 20% of the total amount, and alkaline earth metals are used as a catalyst. The method of producing high-substituted cationic starch according to claim 1, wherein all starches capable of industrial mass production such as corn starch, wheat starch, potato starch, tapioca starch, rice starch and the like are used as starch. According to claim 1, Starch is used to replace the hydroxyl group in the glucose molecule for the modification of the starch itself, or use a cross-linked starch in the form of ether, ester (Ester) or crosslinking A method for producing a highly substituted cationic starch, characterized by using starch and phosphate starch. The method of claim 1, wherein the starch is starch as a starch, wherein the polymer monomer is CH2 = CH-X, wherein X is one of hydrophobic -CN, -CO ₂ R (e.g. acrylonitrile) or -CO _Of high-substituted cationic starches characterized by using starch grafted using one of ₂ H, -CONH ₂ , -CO (CH ₂ ) n and -N + RC 1-such as acrylic acid. Manufacturing method. The preparation of the highly substituted cationic starch according to claim 1, wherein the main blade speed in the mixer is 5-50 m / sec, the rotation speed of the chopper is 1000-3000 rpm, and the reaction temperature is 15 ° C-60 ° C. Way.