JPS6344769B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing graft-modified starch, and more particularly, to a method for producing graft-modified starch in which graft polymerization is carried out while maintaining the granular state of raw material starch. Generally, graft-modified starch is produced by dispersing or dissolving raw starch in a solvent such as water, adding a monomer having an addition-polymerizable double bond to the slurry, and using a graft polymerization initiator. A graft polymerization reaction is carried out at a relatively low temperature, for example, 70°C or lower,
It is then manufactured by washing, filtering, and drying, or it is manufactured by making starch into a paste at a relatively high temperature, for example, 70°C or higher, causing a graft polymerization reaction, and then drum drying, etc. . However, the method of carrying out the graft polymerization reaction in slurry has a high graft efficiency (the amount of monomers polymerized).
It means the percentage (%) of the amount of grafted monomer (g) relative to (g). ), and in particular, when water-soluble monomers such as acrylic acid, methacrylic acid, acrylamide, and some (meth)acrylates, such as dimethylaminoethyl methacrylate, are used, the grafting efficiency decreases due to homopolymerization. Moreover, since the homopolymer is homopolymerized, filtration and drying after polymerization are difficult, resulting in a decrease in yield. Furthermore, when graft polymerization is carried out in the form of a paste, it is naturally impossible to maintain the powder state, and furthermore, catalysts such as graft polymerization initiators, homopolymers, etc. are extremely difficult to remove. The present inventors have conducted extensive research in order to resolve various drawbacks in the conventional production of graft-modified starch. As a result, under certain conditions, starch with monomers and solvent adsorbed can be easily fluidized by stirring. By performing a graft polymerization reaction in a miscible state,
The inventors have discovered that graft-modified starch can be obtained efficiently and have completed the present invention. That is, according to the present invention, the amount of vinyl monomer is 0.01 to 10 parts by weight of starch (as anhydride).
Add 100 parts by weight and 5 to 90 parts by weight of solvent,
Graft-modified starch is obtained using a redox polymerization initiator at ~50°C. In the method of the present invention, graft polymerization is carried out while maintaining the granular state of the raw starch, so even when water-soluble monomers are used, the monomers do not stick to the periphery of the starch or undergo homopolymerization. In addition, there is no need for a filtration step as in conventional methods, and graft-modified starch can be obtained extremely efficiently. The raw material starch may be any commonly used starch, such as potato starch, sweet potato starch, corn starch, high amylose corn starch,
Natural starches such as wheat starch, rice starch, tapioca starch, sago starch and their decomposition products, amylose and amylopectin fractions, cross-linked starch, etherified starch,
Various modified starches such as esterified starch, oxidized starch, acid-treated starch, enzyme-modified starch, roasted starch, wheat flour,
Examples include starch-containing materials such as corn flour and dried sweet potato. The monomers used may be water-soluble or water-insoluble;
The water-soluble monomer includes at least one hydrophilic group (for example, a carboxyl group, a carboxylic anhydride group, a carboxylic acid group, a sulfonic acid group, a sulfonic acid group, a hydroxyl group, an ether group, an amide group, an amino group, A monoethylenically unsaturated monomer having a quaternary ammonium base, etc.) can be used. Examples of such monomers include the following. (1) Carboxyl group-containing monomers: monoethylenically unsaturated mono- or polycarboxylic acids, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc. (2) Carboxylic anhydride group-containing monomer: monoethylenically unsaturated polycarboxylic anhydride, such as maleic anhydride. (3) Carboxylic acid group-containing monomers: Water-soluble salts such as alkali metal salts, ammonium salts, and amine salts of monoethylenically unsaturated mono- or polycarboxylic acids, such as sodium acrylate, sodium methacrylate, and triacrylate. Ethanolamine salt, triethanolamine methacrylate salt, sodium maleate, methylamine maleate salt, etc. (4) Sulfonic acid group or sulfonic acid group-containing monomer: aliphatic or aromatic vinylsulfonic acid or a water-soluble salt thereof, such as vinylsulfonic acid, allylsulfonic acid, vinyltoluenesulfonic acid, styrenesulfonic acid, or sulfonic acid group. propyl acrylate, sulfopropyl methacrylate,
Acrylic sulfonic acids such as 2-hydroxy-3-acryloxypropylsulfonic acid and 2-hydroxy-3-methacryloxypropylsulfonic acid, and their alkali metal salts, ammonium salts, and amine salts. (5) Monomers containing hydroxyl or ether groups: monoethylenically unsaturated esters of polyols such as monoethylenically unsaturated alcohols (e.g. allyl alcohol, metaallyl alcohol, etc.), alkylene glycols, glycerin, polyoxyalkylene glycols, etc. Ethers (e.g. hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, triethylene glycol acrylate,
triethylene glycol methacrylate, poly(oxyethylene-oxypropylene) glycol monoallyl or methalyl ether (which may be random or blocked, and the terminal hydroxyl group may be etherified or esterified), etc.). (6) Amide group-containing monomer: acrylamide, methacrylamide, N-alkylacrylamide, or methacrylamide (for example, N-methylacrylamide, N-hexylacrylamide, etc.),
N,N-dialkyl acryl- or methacrylamide (for example N,N-dimethylacrylamide, N,N-di-1-propylacrylamide, etc.), N-hydroxyalkylacryl- or methacrylamide (for example N-methylolacrylamide, N-methylolmethacrylamide, N-hydroxyethylacrylamide, N-hydroxyethylmethacrylamide, etc.), N,N-dihydroxyalkylacrylamide or methacrylamide (e.g. N,N
-dihydroxyethylacrylamide, N,N
- dihydroxyethylmethacrylamide, etc.),
vinyl lactams (eg, N-vinylpyrrolidone, etc.) and the like. (7) Amino group-containing monomers: amino group-containing esters such as dialkylaminoalkyl esters, dihydroxyalkylaminoalkyl esters, morpholinoalkyl esters, etc. of monoethylenically unsaturated mono- or dicarboxylic acids (e.g., dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, morpholinoethyl acrylate, morpholinoethyl methacrylate, dimethylaminoethyl fumarate, etc.), heterocyclic vinyl compounds (for example, 2-vinylpyridine,
4-vinylpyridine, vinylpyridine such as N-vinylpyridine, N-vinylimidazole, etc.). (8) Quaternary ammonium base-containing monomer: N, N,
N-trialkyl-N-acryloyl- or methacryloyloxyalkylammonium salts (e.g. N,N,N-trimethyl-N-acryloyloxyethylammonium chloride,
N,N,N-trimethyl-N-methacryloyloxyethylammonium chloride, 2-hydroxy-3-acryloyloxypropyltrimethylammonium chloride, 2-hydroxy-3
-methacryloyloxypropyltrimethylammonium chloride, etc.). Further, examples of water-insoluble monomers include the following. (1) Olefinic monomers such as ethylene and propylene. (2) Diene monomers such as butadiene, isoprene, chloroprene, piperylene, etc. (3) Halogenated ethylene monomers such as vinyl chloride and vinylidene chloride. (4) Substituted styrene monomers such as styrene, methylstyrene, ethylstyrene, and chlorostyrene. (5) Unsaturated carboxylic acid ester monomers such as acrylic esters, methacrylic esters, and dimethyl maleate. (6) Acrylonitrile monomers such as acrylonitrile, methacrylonitrile, and chloroacrylonitrile. (7) Vinyl ester monomers such as vinyl acetate and vinyl formate. (8) Vinyl ether monomers such as ethyl vinyl ether and propyl vinyl ether. (9) Vinyl ketone monomers such as methyl vinyl ketone and acrolein. These monomers may be used alone or in combination of two or more, and the amount used can be appropriately selected depending on the desired grafting ratio, but is usually 0.01 to 100 parts of starch.
Preferably, 100 parts are used. In addition, when the monomer is in liquid form, in order to prevent the starch from losing its granular state, it should be added in an amount of 100 parts or less per 100 parts of starch, preferably
It is desirable to use it in a range of 0.1 to 50 parts. Examples of the solvent used include alcohols such as methanol, ethanol, propanol, and butanol, organic solvents such as acetone, benzene, and toluene, water, and mixed solvents thereof. Use 5 to 90 parts including the water content. If the solvent is too large, the starch will lose its powdery state, and if it is too small, the graft polymerization reaction will be difficult to proceed. Monomers, redox polymerization initiators such as ceric salts, persulfate-sulfites, hydrogen peroxide-metal salts, and solvents can be added to the raw starch as appropriate. In addition, the method for adding monomers and polymerization initiators is to disperse them in a solvent and spray this dispersion onto starches.
It is preferable to filter the starch after immersing it in the dispersion. Further, the graft polymerization reaction is preferably carried out in an inert gas such as nitrogen gas or carbon dioxide gas. The obtained graft-modified starch can be used as a sizing agent, coating agent, internal additive, etc. for paper and fibers, depending on its performance.
As various water-soluble film molding materials, adhesives, rewetting adhesives, etc., and as excipients, binders, emulsion stabilizers, water retention agents, thickeners, etc. in various cosmetics, water-soluble paints, paints, etc. Can be used. Next, the present invention will be explained in more detail with reference to Examples. Example 1 1 kg of methacrylic acid, 40 g of ceric ammonium nitrate, and 10 ml of nitric acid are dissolved in a mixed solvent of 50 ml of water and 50 ml of methanol. This solution was sprinkled on 2 kg of tapioca starch (moisture 12%) and mixed, and the reaction was carried out at 50°C for 2 hours in a stirring tank with a heating jacket. A tapioca starch-polymethacrylic acid graft copolymer with a ratio of 45.6% to the weight of raw material starch was obtained. Comparative Example 1 1 kg of methacrylic acid, 40 g of ceric ammonium nitrate and 10 ml of nitric acid were dissolved in 12 kg of water, then 2 kg of tapioca starch (water content 12%) was added, and the mixture was heated at 50°C for 2 kg.
Perform a time reaction. After the reaction, the mixture was washed with water to obtain a tapioca starch-polymethacrylic acid graft copolymer with a methacrylic acid grafting rate of 20.8%. Example 2 Add ascorbic acid to 2 kg of sago starch (moisture 8%)
Dissolve 3g in 200ml of ethanol and spray.
Mix this with 2-hydroxyethyl acrylate.
400 g of hydrogen peroxide and 3 ml of hydrogen peroxide (30% aqueous solution) were dissolved in 50 ml of water, sprinkled on the above sago starch, mixed, and reacted at room temperature (25°C) for 2 hours. A starch-poly 2-hydroxyethyl acrylate graft copolymer was obtained. Comparative example 2 Ascorbic acid added to 2 kg of sago starch (8% moisture)
3g, 2-hydroxyethyl acrylate 400g,
Add 6 ml of water, and while stirring at 20°C, 3 ml of hydrogen peroxide solution was dissolved in 50 ml of water, and the mixture was reacted for 2 hours while being added dropwise. After the reaction, the mixture was washed with water to obtain a sago starch-poly 2-hydroxyethyl acrylate graft copolymer with a 2-hydroxyethyl acrylate grafting rate of 11.7%. Example 3 500 g of acrylamide (powder), 40 g of ceric ammonium nitrate, and 10 ml of nitric acid are dissolved in 100 ml of water. Add this solution to 2 kg of acid-treated starch (moisture 13%).
Spray, mix and mix in a stirring tank with heating jacket.
The reaction was carried out at 50°C for 2 hours to obtain an acid-treated starch-polyacrylamide graft copolymer with an acrylamide grafting rate of 22.3%. Comparative Example 3 2 kg of acid-treated starch (moisture 13%), 500 g of acrylamide (powder), and ceric ammonium nitrate
Add 40 g, 10 ml of nitric acid, and 6 ml of water, and react at 50°C for 2 hours. After the reaction, the mixture was washed with water to obtain an acid-treated starch-polyacrylamide graft copolymer with an acrylamide grafting rate of 10.2%. Example 4 Grafting efficiencies for Examples 1 to 3 and Comparative Examples 1 to 3 were determined and compared in a table.

【table】

【table】

【table】

Claims (1)

[Claims] 1 0.01 to 100 parts by weight of vinyl monomer and 5 parts by weight of solvent to 100 parts by weight of starch (as anhydride)
A method for producing graft-modified starch, which comprises adding ~90 parts by weight and carrying out a polymerization reaction at 5 to 50°C using a redox polymerization initiator.