JP2008230996A - Method for producing gel containing carboxymethylcellulose as main component, and gel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inexpensively and readily producing gel being friendly to the environment having high elasticity and high strength, and to provide the gel obtained by the method. <P>SOLUTION: The method for producing the gel comprises simply mixing carboxymethylcellulose (CMC) as a main component with an acid or an aqueous solution of the acid, and a water-insoluble metallic compound, to gelatinize CMC. The gel obtained by the method has high elasticity and high strength, and can inexpensively and readily be obtained. The gel is friendly to the environment which is obtained by using CMC as a material originated from a plant. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a production method for gelling a carboxymethylcellulose alkali metal salt (hereinafter abbreviated as CMC) to obtain a highly elastic and high-strength environmentally friendly gel and a gel obtained by the method. The gel thus obtained is useful for livestock excrement treatment materials, wastewater treatment materials, deodorizing materials, catalyst carriers, impact absorbing materials, medical adhesive materials, medical putty materials, and the like.

  CMC is the most commonly used water-soluble polymer at present. A method of obtaining a gel in which CMC molecules are cross-linked to form a three-dimensional network structure and water is firmly trapped in the network structure is conventionally known. Specifically, a method for producing a gel by crosslinking CMC with polyvalent metal ions (for example, Patent Documents 1 and 2), and a method for producing a gel by adding a crosslinking agent to CMC (for example, Patent Document 3). is there. However, these production methods have a drawback that it is difficult to produce a gel having high elasticity. Also known is a method for producing gel by adding water to CMC, kneading it into a paste, and irradiating it with radiation (for example, Patent Document 4). However, this method requires an expensive facility such as a radiation irradiation apparatus, and thus has the disadvantage of increasing the cost and the disadvantage of simplicity.

JP-A-7-90121 JP-A-2005-263858 JP 10-251447 A JP 2005-82800 A

  Recently, the present inventors have also proposed a method for producing a gel by simply adding an acid to CMC, that is, a method for producing a gel simply and inexpensively (Japanese Patent Application No. 2006-250947). However, this method has the disadvantage that the strength and elasticity of the gel are not increased and therefore the application is limited. In addition, in the method of manufacturing by using a polyvalent metal ion and a method of manufacturing by using a cross-linking agent as described in the prior art, it has a drawback that it is difficult to manufacture a gel having high elasticity, The method of irradiating a CMC with water and irradiating it with a radiation requires an expensive facility called a radiation irradiator, which has a drawback that it is expensive and lacks simplicity.

  Accordingly, an object of the present invention is to provide a production method for obtaining an environmentally friendly gel having high elasticity and high strength at low cost and a gel obtained by the method.

  A specific and preferred method for producing a gel of the present invention is characterized in that CMC is gelled by simply kneading CMC as a main component, an acid or an acid aqueous solution and a water-insoluble metal compound. The kneading order of CMC, acid or acid aqueous solution, and water-insoluble metal compound is a very simple method without limitation.

  Preferably the weight of CMC is less than 65% by weight relative to the total weight of the resulting gel. If the CMC weight is 65% or more, it is difficult to uniformly knead, which is not preferable.

  The amount of acid or acid aqueous solution used is preferably 35% to 95% by weight based on the total amount of the gel obtained. If it is less than 35% by weight, it becomes non-uniform, and if it exceeds 95% by weight, gel formation becomes difficult, which is not preferable. The amount of the water-insoluble metal compound used is preferably 1% by weight to 30% by weight with respect to the total amount of the gel obtained. If it is less than 1% by weight, an increase in strength is hardly observed, and if it exceeds 30% by weight, the gel becomes non-uniform, which is not preferable. Preferably, in the above-described production method, the acid or the aqueous acid solution is hydrochloric acid or an aqueous hydrochloric acid solution, and the water-insoluble metal compound is aluminum oxide. A high strength and high elasticity gel can be easily obtained by kneading CMC, hydrochloric acid or hydrochloric acid aqueous solution, and aluminum hydroxide.

  The gel manufactured by the above-described manufacturing method contains CMC as a main component, and contains an acid or an acid aqueous solution and a water-insoluble metal compound. The above acid is preferably hydrochloric acid or an aqueous hydrochloric acid solution. The water-insoluble metal compound is preferably aluminum oxide.

  According to the present invention, unlike a method using a polyvalent metal ion for crosslinking and a gel produced using a cross-linking agent, a highly elastic gel is obtained. An expensive equipment such as an apparatus is unnecessary, and therefore, it can be produced inexpensively and easily. Furthermore, unlike a method using only an acid, a gel having high strength can be produced. That is, the gel obtained by the production method is an environment-conserving gel made from plant-derived material called CMC, which is highly elastic, high in strength, inexpensive and easily obtained, and is a livestock excrement treatment material and wastewater treatment material. It is useful for deodorizing materials, catalyst carriers, impact absorbing materials, medical adhesive materials, medical putty materials, and the like.

  A method for producing a gel according to the present invention will be described with reference to FIG. FIG. 1 is a flowchart showing a schematic configuration of a method for producing a gel according to the present invention.

  In FIG. 1, CMC, an acid or acid aqueous solution, and a water-insoluble metal compound are kneaded by a kneader. As a result, a CMC gel is produced.

  Here, the degree of etherification and viscosity of CMC used are not limited. Moreover, the viscosity here is a viscosity when CMC is a 1% by weight aqueous solution, and the level of the viscosity indirectly indicates the level of the molecular weight. CMC may be used as a powder or an aqueous solution, and is not limited as long as it can be kneaded with an acid or an aqueous acid solution in a wet state. In order to knead more easily, it is desirable to use a solution having a concentration of 5% by weight or more. The acid may be either an organic acid or an inorganic acid, and the kind thereof is not limited. For example, hydrochloric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, nitric acid, formic acid, acetic acid, lactic acid, succinic acid, itaconic acid, maleic acid, oxalic acid, citric acid and the like can be used. Furthermore, the concentration of these acid aqueous solutions is not limited, but 0.1 mol / l or more is desirable for easy kneading.

  The water-insoluble metal compound used in the present invention is not particularly limited as long as it is a metal compound insoluble in water. Metal oxides such as titanium oxide, iron oxide, aluminum oxide, manganese oxide, manganese dioxide, barium sulfate, barium carbonate, Metal salts such as barium phosphate, calcium carbonate, calcium phosphate can be used. Aluminum oxide is particularly preferable.

  Furthermore, the temperature at the time of kneading | mixing CMC and an acid or an acid aqueous solution does not ask | require. In general, the higher the temperature at the time of kneading, the faster the gelation proceeds, but a temperature above which CMC is subject to hydrolysis (about 70 ° C.) should be avoided. Moreover, the time to leave after kneading | mixing CMC, an acid or acid aqueous solution, and a water-insoluble metal compound is not ask | required. When the concentration of the aqueous solution of CMC and the concentration of the aqueous acid solution are high, gelation proceeds instantaneously. In general, the longer the standing time, the higher the proportion of water-insoluble parts, that is, gel parts. Hereinafter, preferred examples of the present invention will be described, but the present invention is not limited to these examples.

Commercially available CMC (manufactured by Daicel Chemical Industries, Ltd., degree of etherification 1.36, viscosity of 1% concentration solution at 25 ° C. is 1640 mPa · s) 20 g and commercially available titanium oxide anatase type (Wako Pure Chemicals 202-01725) 5 g was added to 75 g of 1 mol / l hydrochloric acid, and kneaded at 2000 rpm for 20 minutes using a supermixer, Super Mixer Foaming Netaro, and degassed for 10 minutes. The kneaded and paste-like sample was placed in a Teflon (registered trademark) frame having a diameter of 20 mm and a thickness of 10 mm and molded. After the molded sample was stored at 30 ° C. for 7 days, the physical properties were measured with a small desktop tester EZTest manufactured by Shimadzu Corporation. The gel was compressed with a Teflon (registered trademark) compression jig having a diameter of 50 mm, and the breaking strength of the gel was measured. The breaking strength was 0.88 N / mm ² . Further, the elastic modulus at 50% compression was measured with the same testing machine. The elastic modulus was 1.12 N / mm ² , and the gel retained its original shape even after 50% compression twice, and showed high recovery force and high elasticity.

10. Commercially available CMC (manufactured by Daicel Chemical Industries, Ltd., degree of etherification 1.36, 1% strength solution with a viscosity at 25 ° C. of 1640 mPa · s) 40 g and commercially available aluminum oxide (Wako Pure Chemicals 012-01965) 6 g was added to 46.4 g of 1 mol / l hydrochloric acid, and kneaded at 2000 rpm for 20 minutes using a supermixer made by Shinky Super Mixer Foaming Netaro and defoamed for 10 minutes. The kneaded and paste-like sample was spread to a thickness of 10 mm and punched with a cork borer to obtain a sample. The punched sample was stored at 30 ° C. for 7 days, and then the breaking strength of the gel was measured with a Toyo Seiki Strograph VE5D. The breaking strength was 5.87 N / mm ² . Moreover, the elastic modulus at the time of 50% compression was measured with a small tabletop tester EZTest manufactured by Shimadzu Corporation. The elastic modulus was 7.9 N / mm ² , and the gel retained its original shape even after 50% compression twice, and showed high recovery force and high elasticity.

Comparative Example 1

20 g of commercially available CMC (manufactured by Daicel Chemical Industries, Ltd., degree of etherification 1.36, viscosity of 1% concentration solution at 25 ° C. at 1640 mPa · s) is added to 80 g of 1 mol / l hydrochloric acid, and a supermixer foam mixer made by Sinky Taro was kneaded for 20 minutes at 2000 rpm and defoamed for 10 minutes. The kneaded and paste-like sample was put into a Teflon (registered trademark) frame having a diameter of 20 mm and a thickness of 10 mm and molded. After the molded sample was stored at 30 ° C. for 7 days, the physical properties were measured with a small desktop tester EZTest manufactured by Shimadzu Corporation. The gel was compressed with a Teflon (registered trademark) compression jig having a diameter of 50 mm, and the breaking strength of the gel was measured. The breaking strength was 0.44 N / mm ² . Further, the elastic modulus at 50% compression was measured with the same testing machine. The elastic modulus was 0.16 N / mm ² , and the gel did not return to its original shape after 50% compression twice.

Comparative Example 2

40 g of commercially available CMC (manufactured by Daicel Chemical Industries, Ltd., etherification degree 1.36, 1% concentration solution at 25 ° C. with a viscosity of 1640 mPa · s) is added to 60 g of 1 mol / l hydrochloric acid, and a supermixer foam mixer made by Sinky Taro was kneaded for 20 minutes at 2000 rpm and defoamed for 10 minutes. The kneaded paste-like sample was spread to a thickness of 10 mm, punched out with a cork borer, and used as a sample. After the punched sample was stored at 30 ° C. for 7 days, physical properties were measured with a small table tester EZTest manufactured by Shimadzu Corporation. The gel was compressed with a Teflon (registered trademark) compression jig having a diameter of 50 mm, and the breaking strength of the gel was measured. The breaking strength was 1.03 N / mm ² .

  The production method of the present invention described above yields a highly elastic gel as compared with the production method using a polyvalent metal ion or a crosslinking agent, and there is no need for expensive equipment such as a radiation irradiation device, unlike the method using radiation irradiation. Since it is necessary, it can be produced inexpensively and easily, and further, a gel having high strength can be produced unlike a method of producing using only an acid. That is, the gel obtained by the production method is highly elastic, high in strength, inexpensive and easily obtained, and is an environmentally friendly gel made from a plant-derived material called CMC.

  The gel produced as described above is easily produced with high elasticity, high strength, low cost, and can be used in a wide range of fields such as agriculture, industry, medicine, food, etc. It is useful for wastewater treatment materials, deodorizing materials, catalyst carriers, impact absorbing materials, medical adhesive materials, medical putty materials, and the like.

It is a flowchart which shows schematic structure of the manufacturing method of the gel which concerns on this invention.

Explanation of symbols

  CMC Carboxymethylcellulose alkali metal salt

Claims (5)

  A carboxymethyl cellulose alkali metal salt characterized by kneading an acid or an acid aqueous solution and a water-insoluble metal compound with a carboxymethyl cellulose alkali metal salt (CMC) as a main component to gel the carboxymethyl cellulose alkali metal salt. The manufacturing method of the gel used as a component.   2. The method for producing a gel according to claim 1, wherein the weight of the carboxymethyl cellulose alkali metal salt (CMC) with respect to the total weight of the gel mainly composed of the carboxymethyl cellulose alkali metal salt is less than 65%. The manufacturing method of the gel which has the carboxymethylcellulose alkali metal salt as a main component.   The method for producing a gel according to claim 1 or 2, wherein the acid or the aqueous acid solution is hydrochloric acid or an aqueous hydrochloric acid solution, and the water-insoluble metal compound is aluminum oxide (CMC). ) As a main component.   A gel comprising carboxymethylcellulose alkali metal salt (CMC) as a main component, and further comprising an acid or an aqueous acid solution and a water-insoluble metal compound.   The gel according to claim 4, wherein the acid or the aqueous acid solution is hydrochloric acid or an aqueous hydrochloric acid solution, and the water-insoluble metal compound is aluminum oxide.

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