JPS6223763B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a modified starch that has high viscosity dilution resistance and can be used as a thickener and a polymer flocculant. Conventionally, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, guar gum, carboxymethyl starch polyethylene oxide, sodium polyacrylate, etc. have been known as high viscosity thickeners, but they have a high viscosity and dilution resistance, especially at an aqueous solution concentration of 1% or less. It has the disadvantage that it does not have sufficient dilution resistance and forms so-called lumps when dissolved, so it must be dispersed in hot water and then dissolved. Furthermore, carboxymethyl starch and anionic modified starch obtained by graft-copolymerizing starch with a monomer having an anionic substituent, which have been conventionally used, have not been provided with sufficient thickening effect and coagulation effect to date. The present inventors have conducted intensive research to solve these drawbacks, and as a result, we have found that graft-modified starch, which has anionic substituents introduced into both the starch as the backbone polymer and its graft side chain, has excellent physical properties for this purpose. The present invention was completed based on the discovery that this shows the following. That is, the anionic graft-modified starch of the present invention uses an anion-modified starch with a degree of substitution of 0.01 to 0.9 as a backbone polymer, and introduces an anionic substituent using a monomer having an anionic substituent as a side chain or by a saponification reaction. It is produced by graft copolymerizing monomers that can be used at a graft ratio of 0.01 to 40%. Further, the anionic graft-modified starch of the present invention is characterized in that it maintains the powdery state of starch and exhibits excellent thickening effect and aggregation effect with a low degree of substitution and a low grafting rate. That is, anionically modified starch that simply has an anionic substituent on the starch that is the backbone polymer or anionic graft-modified starch that has an anionic substituent only on the side chain usually does not exhibit sufficient thickening effect or aggregating effect. In addition, increasing the degree of substitution and grafting rate in order to improve the thickening effect and aggregation effect not only increases the cost, but also increases the cost of increasing the degree of substitution and grafting in order to improve the thickening effect and aggregation effect. There is also a big disadvantage in terms of production because the starch cannot be kept in a powdery state and becomes pasty. Examples of anionizing agents for anionically modifying starches, which are main polymers, include monochloroacetic acid, propanesultone, etherifying agents such as sodium 3-chloro-2-hydroxy-sulfonate, orthophosphoric acid, sodium tripolyphosphate, phosphoric anhydride, trimetaphosphate, hexametaphosphate, maleic anhydride,
Esterifying agents for dibasic acid anhydrides such as succinic anhydride and phthalic anhydride, and tribasic acid anhydrides such as mellitic anhydride. Monomers having anionic substituents that can be graft copolymerized as side chains include acrylic acid, methacrylic acid, vinyl sulfonic acid, allyl sulfonic acid,
Vinyltoluenesulfonic acid, styrenesulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloxypropylsulfonic acid, 2-hydroxy-3
-methacryloxypropylsulfonic acid, (2-acryloyloxyethyl) acid phosphate,
Alkali metal salts such as (2-methacryloyloxyethyl) acid phosphate, ammonium salts,
Examples include amine salts. Examples of monomers into which anionic substituents can be introduced by saponification include methyl acrylate, ethyl acrylate, propyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate. Furthermore, a water-soluble monomer copolymerizable with the above monomer may be copolymerized. The starch used as raw material starch in the present invention is
Natural starches such as potato starch, sweet potato starch, corn starch, waxy corn starch, high amylose corn starch, wheat starch, rice starch, tapioca starch, sago starch and their decomposition products, amylose and amylopectin fractions, wheat flour, corn flour , dried sweet potato, dried tapioca, and other starch-containing products. Anionic etherification and/or anionic esterification modified starch can be obtained from these raw material starches according to conventional methods. For example, to obtain carboxymethyl starch, starch is reacted with monochloroacetic acid in an organic solvent-water system in the presence of caustic soda. In addition, in order to graft copolymerize an anionic monomer as a side chain, a ceric salt,
Using common graft polymerization initiators such as persulfate, persulfate-sulfite, and hydrogen peroxide-metal salts,
It can be carried out according to a conventional method at a temperature of -95°C, preferably 10-60°C. The thickener and flocculant using the highly viscous graft-modified starch obtained by the present invention have anionic substituents on both the starch backbone polymer and the graft side chain, and have a wide pH range from weakly acidic to strongly alkaline. It exhibits excellent thickening and cohesive properties in various areas, as well as caking, adhesive, suspending, emulsifying, and oil resistance properties.
It has excellent organic solvent resistance and adsorption to cationic substances, and can be used in detergents, boring mud, cosmetics, fiber walls, binders for mixed fish feed, thickeners for ceramics and plaster, ice glazes, and agricultural chemicals. , spreading agent for seeds, protective film for seeds and bulbs, thickener for paper making, latex, protective colloid for paints and synthetic resins,
Examples include thickeners such as antistatic agents, soil conditioners, printing pastes, and fire extinguishers. The anionic graft-modified starch of the present invention exhibits excellent effects when used primarily as a back stain prevention agent during washing and as a finishing sizing agent. In addition, it can also be used for special purposes such as antistatic and antifouling purposes. Conventionally, carboxymethyl cellulose has shown excellent effects for this type of use, but the anionic graft-modified starch of the present invention shows an effect equal to or better than that of carboxymethyl cellulose, and is also cost-effective. be. In addition, when drilling wells such as oil wells, muddy water is sent into the excavation area through the center of the drill pipe and circulated from the outside of the pipe to the ground together with the drilling debris in order to release the debris to the surface. By adding 0.1 to 1.0% of the graft-modified starch of the present invention to this muddy water, the amount of muddy water can be reduced by 15 to 30% compared to the case where it is not added. In addition, pregelatinized starch, which has not been chemically treated, has conventionally been used as a binder for compound feed for fishing, but because its thickening effect and cohesive strength are weak, a large amount of pregelatinized starch must be mixed. It was not desirable as the nutritional balance was disrupted. When the graft-modified starch of the present invention is used, compared to conventional pregelatinized starch, it exhibits a caking effect in a much smaller amount and is less susceptible to spoilage, thereby preventing deterioration of water quality. The polymer flocculant using the graft-modified starch of the present invention is extremely effective in treating domestic wastewater such as sewage human waste treatment. In addition, fish paste product factories discharge wastewater containing a large amount of protein components, and currently sodium polyacrylate is mainly used to treat this wastewater, but by using the graft-modified starch of the present invention, It can produce similar effects, is cheaper than sodium polyacrylate, and has good solubility, improving workability. Furthermore, in recent years, with the modernization of electrolytic soda equipment, various continuous brine purification methods have been adopted, and at the same time, powerful sedimentation accelerators are used to promote sedimentation and improve purification capacity. Precipitating agents such as anion-modified starch and sodium silicate cannot be expected to have sufficient effects, and a precipitating agent with even stronger sedimentation action is required. However, by using the graft-modified starch of the present invention, sufficient It can be effective. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Carboxymethyl starch 100 with degree of etherification 0.05
1 part, 10 parts of sodium acrylate, 8 parts of ceric ammonium nitrate, and 1 part of nitric acid (63%) were added to 300 parts of water, and the graft modification reaction was carried out at 45°C for 2 hours, followed by washing and drying. Starch A was obtained. Example 2 100 parts of starch phosphate with a degree of substitution of 0.1, 8 parts of mono(2-methacryloylokimiethyl) acid phosphate
parts, 5 parts of 2-hydroxyethyl methacrylate,
8 parts of ceric ammonium nitrate, nitric acid (63
%) was added to 300 parts of water, and a graft modification reaction was carried out at 45° C. for 2 hours, followed by neutralization, washing and drying to obtain graft modified starch B. Example 3 Carboxymethyl starch 100 with degree of etherification 0.05
1 part, 6 parts of sulfopropyl acrylate, 8 parts of ceric ammonium nitrate, and 1 part of nitric acid (63%) were added to 300 parts of water, and a graft modification reaction was carried out at 45°C for 2 hours, followed by neutralization, washing, and drying. Graft modified starch C was obtained. Comparative example 1 100 parts of cornstarch, 10 parts of sodium acrylate
1 part, 8 parts of ceric ammonium nitrate, and 1 part of nitric acid (63%) were added to 300 parts of water, and a graft modification reaction was carried out at 45° C. for 2 hours, followed by washing and drying to obtain graft modified starch D. Comparative Example 2 100 parts of corn starch, 8 parts of mono(2-methacryloyloxyethyl) acid phosphate, 2
- Add 5 parts of hydroxyethyl methacrylate, 8 parts of ceric ammonium nitrate, and 1 part of nitric acid (63%) to 300 parts of water, perform a graft modification reaction at 45°C for 2 hours, and then neutralize, wash, and dry. Graft modified starch E was obtained. Comparative Example 3 100 parts of corn starch, 6 parts of sulfopropyl acrylate, 8 parts of ceric ammonium nitrate
1 part of nitric acid (63%) was added to 300 parts of water, and a graft modification reaction was carried out at 45° C. for 2 hours, followed by neutralization, washing and drying to obtain graft modified starch F. Example 4 100 parts of graft-modified starch D was added to a mixed solution of 100 parts of methanol, 10 parts of monochloroacetic acid, and 20 parts of sodium hydroxide (50% aqueous solution), and an etherification reaction was carried out at 45°C for 8 hours to obtain graft-modified starch G. Obtained. Example 5 Carboxymethyl starch with etherification degree of 0.05 used as raw material for graft modified starch A to C, degree of substitution
Prepare a 1% aqueous solution of 0.1 phosphate starch, corn starch and graft modified starch A, B, C, and G used as raw materials for graft modified starch DEF,
Bruckfield viscosity was measured at 20°C. According to this, carboxymethyl starch and phosphate starch in which only the backbone polymer has been anionically modified, or graft-modified starches D to F in which anionic substituents have been introduced only in the side chains, have almost no viscosity in a 1% aqueous solution, but Graft-modified starches A, B, with anionic substituents introduced into both the polymer and side chains,
C and G have sufficient viscosity. Furthermore, the graft-modified starches A to C of the present invention exhibit higher viscosity than carboxymethyl cellulose or sodium polyacrylate under similar conditions. The results are shown in the table.

[Table] Example 6 Cotton fabrics treated with various 1% aqueous thickening solutions were used as samples, and the results were immersed for 1 hour at 20°C in a contaminated solution in which 0.32% carbon black was dispersed in water or carbon tetrachloride. The contamination rate was measured.

[Table] Example 7 A use test was conducted using sodium polyacrylate, which is currently commonly used as a thickener, graft modified starch A of the present invention, and unmodified cornstarch in the following formulation as a latex thickener. Ta.

[Table] Example 8 Comparative studies were conducted by soaking tuna in ice glaze, which is a type of frozen preservation method, once in a 1% aqueous solution of the graft-modified starch A of the present invention and an additive-free aqueous solution.

【table】

Claims (1)

[Scope of Claims] 1 Anionically modified starch with a degree of substitution of 0.01 to 0.9 as a backbone polymer, having graft side chains with a grafting rate of 0.01 to 40% of a monomer having an anionic substituent, at 20°C, 1 % of a modified starch whose Burdskfield viscosity in aqueous solution is 1000 centipoise or more. 2. The modified starch according to item 1 above, wherein the anionic substituent of the anionic modified starch and the monomer having an anionic substituent is a carboxylate, a sulfonate, or a phosphate.