JPH0931101A - Novel water-absorbing material made of starch lees and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a novel water-absorbing material made of starch lees by esterifying a cellulose-containing product obtained by removing starch from starch lees with phosphoric acid. SOLUTION: This water-absorbing material is obtained by removing starch from starch lees by heating it in an aqueous acid solution and esterifying the obtained cellulose-containing product with phosphoric acid in a urea solution. Examples of the aqueous acid solutions include aqueous solutions of organic acids such as acetic acid, lactic acid and citric acid and inorganic acids such as hydrochloric acid and sulfuric acid. The removal of starch is carried out until the starch contained in the starch lees decreases to 25wt.% or below desirably 5wt.% or below. This material has a water-absorbing capacity of about 190-210g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel water-absorbing material using starch as a raw material after collecting starch from agricultural products such as potatoes or agricultural wastes thereof, and a method for producing the same.

[0002]

2. Description of the Related Art The use and demand of water-absorbing materials, mainly disposable diapers and sanitary articles, are increasing rapidly. This material is obtained by partially cross-linking a water-soluble polymer to make it water-insoluble, and polyvinyl alcohol, polyacrylic acid, or the like is used as a raw material. Therefore, it has poor biodegradability and is not biodegradable when landfilled. Therefore, there is a problem in disposal treatment, and development of a biodegradable water-absorbing material is desired. on the other hand,
In Hokkaido, potatoes are produced in an amount of 2.5 million tons or more annually, and about 60% of the potato starch is used as a starch material. ). Since such starch cake is unsuitable for feed, there is currently no use other than for compost,
There is a strong demand for its application development.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel water-absorbing material using starch lees as a raw material and a method for producing the same.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, there is provided a water-absorbing material comprising a phosphoric acid ester of a fibrous material obtained by removing starch from starch cake. Further, according to the present invention, there is provided a method for producing a water-absorbing material, comprising subjecting starch meal to heat treatment in an acidic aqueous solution to remove the starch, and then subjecting the starch residue to phosphoric acid esterification in a urea solution.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The water-absorbing material of the present invention uses starch lees as a raw material, and the starch lees is preferably potato or sweet potato starch lees. It is preferable that the starch cake is used after being ground or pulverized.

In order to produce a water-absorbing material from starch cake according to the present invention, first, starch contained therein is removed from starch cake. This starch removal can be performed, for example, by subjecting starch cake to heat treatment in an acidic aqueous solution. The acidic aqueous solution can be obtained by dissolving an organic acid such as acetic acid, lactic acid, or citric acid, or an inorganic acid such as hydrochloric acid or sulfuric acid in water. The acid concentration in the aqueous solution is 0.1 to 1 in the case of an organic acid.
0% by weight, preferably 0.5 to 2% by weight, and in the case of an inorganic acid, 0.001 to 1N, preferably 0.01 to 1%.
It is a 0.2 normal solution. Heat treatment temperature is 20-20
The temperature is 0 ° C, preferably 100 to 150 ° C, and the treatment time is 1 to 60 minutes, preferably 10 to 60 minutes. In the present invention, the starch contained in the starch lees is removed as described above until the starch content becomes 25% by weight (dry matter basis) or less, preferably 5% by weight or less. If the starch content in the starch lees exceeds the above range, a water-absorbing material cannot be obtained in a high yield in the subsequent phosphorylation step.

[0007] The destarch product obtained as described above is dried and then phosphorylated. This phosphorylation causes the destarch product to react with phosphoric acid in a urea solution. Per 100 parts by weight of the destarch product, the phosphoric acid is used in an amount of 10 to 150 parts by weight, preferably 25 to 150 parts by weight.
100 parts by weight, and the use ratio of urea is 600 parts by weight.
9000 parts by weight, preferably 1500 to 6000 parts by weight. The reaction temperature is a temperature at which urea shows a liquid state, and preferably 140 to 160 ° C. The reaction time is 20 to 80 minutes, preferably 20 to 60 minutes.
The phosphoric acid esterification product obtained as described above is
This is separated by filtration, washed with water, and then washed with an organic solvent such as acetone to obtain the water-absorbing material of the present invention.

When a highly water-absorbing material is efficiently obtained by the present invention, the starch in the raw starch lees is contained in an amount of 25% by weight.
In the following, preferably 5% by weight or less is removed, and 0.1 to 1.5 parts by weight, preferably 0.25 to 1 part by weight of phosphoric acid is added to 1 part by weight of the destarch product. It is preferable to add and react. In this way,
A highly water-absorbing material having a water absorption capacity of 190 to 210 g / g can be obtained.

[0009] In the phosphoric acid esterification reaction, fibrin contained in the destarch product is reacted with phosphoric acid to be esterified. In this case, the starch, hemicellulose, etc. contained in the de-starched product are also phosphorylated.
The phosphorylated starch and hemicellulose and the phosphorylated low molecular weight cellulose are eluted and removed in the phosphorylation step and the washing step.

The water-absorbing material of the present invention is made of phosphate esterified cellulose, and absorbs and retains water due to its water insolubility and hydrophilicity. The phosphorus content in the water-absorbing material is 1 to 10% by weight, preferably 2 to 8% by weight, more preferably 3 to 6.5% by weight. If the phosphorus content deviates from the above range, it becomes impossible to obtain a material having a good water absorption capacity.

The water-absorbing material of the present invention may optionally contain
Although containing a small amount of impurities such as starchy substances, the presence of such a small amount does not particularly reduce the product value of the water-absorbing material of the present invention.

When producing a water absorbent material according to the present invention,
If the potato epidermis such as potato is mixed into the starch lees, which is the raw material, the resulting water-absorbing material becomes brownish. In such a case, it is preferable to decolorize the starch cake with a bleach such as chlorite. This decolorization treatment may be performed before the starch is removed from the starch cake, but is usually preferably performed after the starch removal. The decolorization treatment of starch lees with chlorite may be performed by a conventional method in a dilute acid aqueous solution while heating, for example, as follows. First, a mixture of 1 part by weight of dried starch cake from which starch was removed by heat treatment in an acidic aqueous solution and 5 to 60 parts by weight of purified water, preferably 15 to 30 parts by weight, was mixed with 0.1 to 0.1 parts by weight of sodium chlorite. 0.6 parts by weight, preferably 0.2 to 0.4 parts by weight, and glacial acetic acid 0.0
2 to 0.12 parts by volume, preferably 0.04 to 0.08 parts by volume, is added every 60 minutes, and the temperature is increased to 50 to 100 ° C, preferably 60 to 80 ° C for 20 to 360 minutes, preferably 60 to 80 ° C.
Hold for ~ 240 minutes. The decolorized product thus obtained is washed, dried, and then subjected to a phosphorylation treatment.

The water-absorbing material of the present invention has a significantly reduced water-absorbing ability once it is completely dried. In such a case, by subjecting the phosphoric acid ester to a heat treatment with an alkaline alcohol aqueous solution, the phosphoric acid ester can be reformed into a water-absorbing material whose water-absorbing ability does not decrease even when water absorption and dehydration are repeated. As a result, the method of transporting and using the product becomes simpler, and the suitability for use as a simple water-absorbing material is expanded. The phosphoric acid ester modification treatment may be performed by a conventional method of introducing a hydrophilic metal ion, for example, as follows. 1 part by weight (dry weight) of phosphoric acid ester and 0.1 to 16 parts by weight of sodium hydroxide, preferably 1 to 4 parts by weight, and an aqueous solution of ethanol: purified water in a volume ratio of 1: 1 to 2: 0 15 To 400 parts by volume, preferably 15 to 100 parts by volume, is added and heated at 20 to 100 ° C., preferably 60 to 100 ° C. for 5 minutes for 120 minutes, preferably 10 to 40 minutes. The alkali-treated product thus obtained is washed and dried to become a water-absorbing material whose water-absorbing ability does not decrease even by absorption and dehydration.

[0014]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The percentages described below are percentages by weight.

Examples 1 to 6 and Comparative Example 1 Powdery potato starch cake having a starch content of 40 to 4000 μm containing 55% starch and 78% water on a dry basis was used as a raw material. After adding 20 kg and treating at 120 ° C. for 30 minutes,
The mixture was heated for 0 hour to dissolve and remove the starch. The solid product obtained after removing the mother liquor by filtering the product after the treatment with an exposed cloth was washed with water and freeze-dried to obtain 2.4 kg of a dried product containing 10% starch. The dried product has a diameter of 40 to 400.
It was a white powder of 0 μm. 2 g of the dried product was placed in a 300-ml Erlenmeyer flask, and phosphoric acid and 60 g of urea in the amounts shown in Table 1 were added thereto.
After immersing in a 0 ° C. oil bath and reacting for 40 minutes, the contents of the flask were filtered with a glass filter to remove the mother liquor. Then, 1 liter of purified water and 0.5 liter of acetone were sequentially poured into the reaction solid matter collected on the glass filter to obtain a reaction solid matter in a contracted state. Further, the reaction solid was washed with 0.5 liter of purified water, and then the glass filter containing the reaction solid was dried in an oven at 110 ° C. for 6 hours, and dried in a yield shown in Table 1.
A powdery solid having the following properties was obtained. In addition, the water absorption shown in Table 1 was calculated from the weight change before and after drying, and the phosphorus content was obtained by a conventional method using the absorbance of phosphomolybdic acid. When water was absorbed by the undried acetone-washed solid, the solid became colorless and transparent.

[0016]

[Table 1]

[0017]

The water-absorbing material of the present invention has biodegradability and does not cause any particular problem in disposal.
Further, it is a water-absorbing material which is colorless and transparent at the time of water absorption and can be eaten, so that it can be used as a food additive or a thickener. Further, since this material contains phosphorus, it is highly useful as a water retention material having a fertilizer effect. The method of the present invention is a method for producing the water-absorbent material of the present invention from starch lees. According to this method, a starch lees having little utility value is used as a main raw material, and the water-absorbent material of the present invention is efficiently produced. Can be.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Yokota 2-17-1, Tsukikanto, Toyohira-ku, Sapporo-shi, Hokkaido Inside Institute of Industrial Science and Technology, Hokkaido Institute of Industrial Technology (72) Naoto Saito 1-line Nishikagura, Asahikawa-shi, Hokkaido No. 10 174 No. 7 Hokkaido Prefectural Forest Proving Ground (72) Inventor Masakazu Aoyama 1-line Nishikagura, Asahikawa-shi, Hokkaido No. 10 174 No. 7 Inside Hokkaido Prefectural Forest Proving Ground (72) One inventor, No. 10 174 Nishikagura, Asahikawa-shi, Hokkaido 7 Hokkaido Prefectural Forest Proving Ground (72) Inventor Mayumi Tsuda No. 10, Nishi Kagura 1 Line 10, 174, Hokkaido 7 Hokkaido Prefectural Forest Proving Ground (72) Inventor Minoru Kubota No. 10, 174 Nishi Kagura, Asahikawa City, Hokkaido 7 Forest Producing Hokkaido Inside the test site

Claims (2)

[Claims] 1. A water-absorbing material comprising a phosphoric ester of a fibrous material obtained by removing starch from starch cake. 2. A method for producing a water-absorbing material, comprising: subjecting starch meal to heat treatment in an acidic aqueous solution to remove the starch, followed by phosphorylation in a urea solution.