JP6281074B2 - Manufacturing method of water-absorbing material - Google Patents

Description

  The present invention relates to a method for producing a naturally-derived water-absorbing material.

  A highly water-absorbing material is a material that can absorb water from several tens to several thousand times its own weight. According to JIS-K-7223, a highly water-absorbing resin having a water absorption performance of 10 g or more per 1 g of resin. It stipulates. At present, a resin obtained by crosslinking sodium polyacrylate with N-N'-methylenebisacrylamide is widely used as a typical synthetic superabsorbent resin. Synthetic superabsorbent resins are widely used in disposable hygiene products and the like, but their biodegradability is low, and their disposal method is problematic.

  Starch, which is a naturally derived material, or cellulose such as pulp or paper has water absorbency, and is superior to synthetic high water-absorbent resins in terms of biodegradability. However, the water absorption of cellulose is due to the capillary phenomenon between the fibers, and does not reach the synthetic high water absorption resin. Also, the water-absorbing material derived from starch has low water absorption performance and is not classified as high water absorption. Furthermore, since starch becomes a slurry when it absorbs water, it is difficult to handle.

  In addition to cellulose and starch, xanthan gum-derived polymers (Patent Document 1) and Karaya gum-derived polymers (Patent Document 2) are known as highly water-absorbing materials mainly composed of naturally occurring polysaccharides.

JP 2003-192703 A JP-A-2005-246121

However, xanthan gum and karaya gum, which are naturally derived polysaccharides, are water-soluble and, like starch, dissolve when water is absorbed and are difficult to handle. In order to solve this problem, in Patent Document 1, the xanthan gum is heated at 90 ° C. to 120 ° C. or mixed with a poor solvent for xanthan gum and then heated. Moreover, in patent document 2, after adding polycarboxylic acid to Karaya gum, it heats at 120 to 180 degreeC, and performs surface crosslinking. Thus, in order to use naturally-derived polysaccharides as water-absorbing materials, it is generally necessary to perform extraction and purification operations from natural materials, and further, in order to insolubilize the materials, such as Karaya gum and xanthan gum. Need.
Today, there is a demand for naturally-derived water-absorbing materials that can reduce the running cost without adding the availability and processing of the materials.

  As a result of researches on naturally-derived water-absorbing materials, the present inventors have found that oil palm-derived tree tissues that have been discarded without being used so far have high water absorption, and complete the present invention. It came to.

  That is, the present invention provides a method for producing a water-absorbing material, the main component of which is a fine particulate material called soft tissue in the trunk, obtained from an oil palm trunk. The soft tissue in the oil palm trunk is a fine particulate material present in the woody part inside the trunk. The water-absorbing material of the present invention can be obtained by squeezing sap from the felled oil palm trunk to obtain a residue, drying the residue after squeezing, and separating the soft tissue from the solid content in the woody part. .

The water-absorbing material obtained by the present invention is a naturally derived material, and can be used in various fields such as animal excreta treatment, feed additives, agricultural and horticultural materials.
In addition, unlike xanthan gum and karaya gum, it is not necessary to perform heat treatment or the like, and can be manufactured at low cost.

It is an image which shows the external appearance of the oil palm trunk used for this invention. It is sectional drawing which cut | disconnected the oil palm trunk in the vertical direction according to the broken line of FIG. It is a figure which shows the image (x1) of the soft tissue derived from oil palm. It is a figure which shows the image (x1) of the vascular bundle derived from an oil palm. It is a figure which shows the enlarged image (x150) of the soft tissue derived from oil palm. It is a figure which shows the image (x550) of the vascular bundle derived from an oil palm. It is a figure which shows the enlarged image (x370) after the ball mill process of the soft tissue derived from an oil palm.

  Oil palm is a plant of the palm family that is cultivated to collect palm oil, and is cut and replanted approximately every 25 years in order to maintain oil and fat productivity. In Malaysia, about 30 million hectares of oil palm are currently being harvested because about 40,000 hectares are replanted annually. However, the trunk of the palm is rarely reused. ing.

  FIG. 1 shows the appearance of the oil palm trunk. FIG. 2 is a cross-sectional view of the oil palm trunk cut in the longitudinal direction as indicated by broken lines in FIG. As shown in FIG. 2, the oil palm trunk constitutes a woody part composed of a soft tissue 1, a vascular bundle 2 and a bark 3. Since the outer layer portion near the bark 3 has a relatively low water content, the outer layer portion is used for plywood only in the outer layer portion. However, regarding the soft tissue 1 and the vascular bundle 2, it has only been studied to hydrolyze and use as a raw material for ethanol fermentation, and its use has not been established yet. In addition, since a large amount of fermentable hexose suitable for ethanol fermentation is contained in a large amount of sap contained in the felled oil palm trunk, the present inventors have reported that the sap can be directly used as a raw material for ethanol fermentation. ing.

  The oil palm trunk can be easily divided into fine powdery solid solids and acicular solids with a sieve after drying the water-insoluble component after collecting the sap, that is, the juice residue. In the present specification, the powdery fine particulate solid is called soft tissue. It is also possible to dry the felled oil palm trunk without squeezing the sap and separate the soft tissue from the woody part.

  The soft structure of oil palm, that is, the water-absorbing material of the present invention has a porous structure in which fine pores are densely packed, and this porous structure is considered to play an important role in water absorption performance.

  Oil palm soft tissue can be obtained by simply defibrating and drying the wood part of the oil palm trunk tree, and does not require additional treatment such as heat treatment at high temperatures. Therefore, the running cost can be reduced as compared with the extraction and purification of polysaccharides.

  The soft tissue of oil palm swells when water is added, but is not gel-like when it does not contain water.

  A major feature is that even if salts and organic components are contained in the moisture, the water absorption capacity of the soft tissue is hardly changed. For this reason, soft tissue is applied to water-absorbing articles intended to absorb body fluids such as urine, sweat, saliva, blood, etc., such as paper diapers, portable toilets, pet excreta absorbers, meat and fish freshness preservation materials, etc. can do. In addition to body fluids, water-absorbing articles for civil engineering materials that absorb muddy water, river water, seawater, soil and fertilizers can be used as soil improvement materials, or agricultural and horticultural materials such as water retention materials in dry land It can be used in a wide range, for example, as a water-absorbing article.

  The soft tissue may be used alone, for example, by wrapping it with a cloth or non-woven fabric to form a water absorbing article.

  The water-absorbing material of the present invention may contain water in advance and be mixed with an inorganic substance, soil, or fertilizer.

  Hereinafter, the water-absorbing material and the production method thereof according to the present invention will be described based on examples. In addition, this invention is not limited to the following Example.

  The oil palm trunk is divided into a hard bark surrounding the outside and a yellowish white wood part. The solid residue after squeezing the woody part and squeezing the sap was dried at 60 ° C. for 1 to 3 days, except for the bark of the felled oil palm. When the dried product was lightly pulverized in a mortar and fractionated with a sieve, it could be divided into fine powdery particles, that is, soft tissue (diameter of about 30 μm to 50 μm) and needle-like hard solids, that is, vascular bundles. A soft tissue image is shown in FIG. 3, and a vascular bundle image is shown in FIG. About 50 to 60% of the woody part was soft tissue and the rest was vascular bundle.

  The soft tissue and vascular bundle were dried at 70 ° C. for 1 day. 1 g of each solid content was weighed and placed in a tea bag under conditions that allow free swelling (size of bag that does not rupture even if it absorbs water 100 times) and was immersed in 1 liter of distilled water at 20 ° C. for 1 hour. Thereafter, the tea bag was suspended for 3 hours to drain water, then weighed (20 ° C.), and the water absorption capacity was determined from the weight difference from the resin amount before immersion by the following formula. The results are shown in Table 1.

Water absorption ratio = (resin amount after immersion (g) −resin amount before immersion (g)) / resin amount before immersion (g)

  For comparison, microcrystalline cellulose powder (Sigma Cell; Sigma Aldrich), cellulose powder (Whatman), starch (from corn; Wako Pure Chemical), silica gel (Wako Pure Chemical), agar (for microbial culture; Wako Pure Chemical), 1 g each of duran gum (Wako Pure Chemical Industries) was weighed and placed in a tea pack bag under conditions that allow free swelling (size of bag that does not rupture even if it absorbs water 100 times) and was immersed in 1 liter of 20 ° C. distilled water for 1 hour. Thereafter, the tea bag was suspended for 3 hours to drain water, and then weighed (20 ° C.) (this was referred to as the resin amount after immersion), and the water absorption ratio was determined from the weight difference from the resin amount before immersion. The results are shown in Table 1.

From this result, it became clear that the solid content obtained from the oil palm trunk, particularly the soft tissue, has very high water absorption performance. The vascular bundle had a water absorption ratio of 1.4 times, but the soft tissue showed a water absorption ratio of about 20 times. That is, it can be seen that the water-absorbing material of the present invention has performance comparable to that of the highly water-absorbent resin specified in JIS Method-K-7223.

  Solids from oil palm trunks are known to contain cellulose, hemicellulose, and a small amount of starch as their constituents, but they have extremely high water absorption compared to commercially available cellulose and starch components listed as comparative examples. Showed the ability. Therefore, in the water absorption performance in this soft tissue, it has shown that it has water absorption ability by the function or structure different from the water absorption ability which a cellulose and starch have. Moreover, it turns out that the water absorption capacity | capacitance comparable to the natural-derived duran gum commercialized is shown.

In order to examine the water absorption characteristics of the soft tissue, the water absorption effect of a solution containing a high salt concentration or a solution containing an organic solvent was tested.
1 g of soft tissue was placed in a tea pack bag and immersed in 1 liter of a 20% sodium chloride 5% (w%), 10%, 20% solution. The results are shown in Table 2.
As for solutions containing organic solvents, methanol (Wako Pure Chemicals special grade)-distilled water 10%, 30% (v%) solution, and ethanol (Wako Pure Chemicals special grade)-distilled water 10%, 30% (v%) Each solution was prepared and immersed. The results are shown in Table 3.

  Compared to the water absorption capacity of soft tissue immersed in distilled water, almost no change was observed in the water absorption capacity immersed in 5%, 10%, and 20% sodium chloride solutions. In addition, when immersed in an aqueous solution of methanol or ethanol, a slight decrease in water absorption capacity was observed, but the water absorption capacity was almost the same as distilled water. From these results, it became clear that the soft tissue has the same hygroscopicity as distilled water even in a solution containing a high salt concentration or a solution containing an organic solvent.

  In order to examine in detail the water absorption capacity of the oil palm trunk soft tissue, the structure was observed with an electron microscope of the prepared soft tissue. The electron microscope image is shown in FIG. FIG. 5 reveals that the soft tissue has a structure in which fine porous structures such as egg shells are densely packed. On the other hand, as shown in FIG. 6, it can be seen that fine pores are not densely packed in the vascular part, and that the structure is completely heterogeneous.

  In order to confirm whether or not this structure is related to water absorption, ball mill treatment (5 minute interval, 6 hour treatment) was performed, and this porous structure was destroyed and confirmed by an electron microscope. The electron microscope image is shown in FIG. As a result, it was confirmed that 80% or more of the porous material was broken and destroyed. As a result of the same immersion treatment using the soft tissue in which the porous structure was destroyed, the water absorption ratio was significantly reduced to 2.5 times. From these results, it was revealed that the porous structure of the soft tissue is important for the water absorption capacity of the soft tissue.

In order to confirm the biodegradability of the soft tissue, the soft tissue was immersed in 0.05 M phosphate buffer pH 5.5, and then the excess water removed by gauze was transferred to a petri dish, and about 0. Mixed with 5 g, spread flatly to make a solid medium and cultured at 30 ° C. Vigorous growth of filamentous fungi was mainly confirmed on the second day of culture.
In order to confirm whether soft tissue can be decomposed by mold enzyme, 1 ml of commercially available mold enzyme (Sigma, Cellulase) is added to 1 g of soft tissue and reacted at 50 ° C. in an acetate buffer (pH 5.0) for 48 hours. It was. After the reaction, the decomposition solution was centrifuged at 14,000 rpm at 4 ° C. for 5 minutes, and the supernatant was diluted with distilled water to an appropriate concentration, and the sugar composition was measured.
Each free sugar contained in the decomposition solution was measured by high performance liquid chromatography (Prominence, manufactured by Shimadzu Corporation) using a differential refraction detector with an Aminex HPX-87P column (Bio-Rad).
As a result, cellobiose, glucose, xylobiose, xylose, and arabinose were detected and confirmed to be degraded by the enzyme. From these results, it was confirmed that soft tissue is a superabsorbent material with biodegradability.

  From the above results, it has been clarified that the high water absorption performance of the soft tissue prepared from the oil palm trunk depends on its unique porous structure characteristics, and further has biodegradability. Therefore, the solid content prepared from the oil palm trunk, particularly the soft tissue, can be used as a highly water-absorbing material.

  The water-absorbing material obtained by the present invention may be wrapped with a water-permeable material such as paper or cloth to form a water-absorbing article. In addition, because of its porous structure characteristics, water absorption performance hardly deteriorates even in solutions containing high salt concentrations such as seawater or flammable organic solvents. It can also be used as a poor environmental improvement material in the region. It can also be used as a soil conditioner that absorbs moisture and gradually releases the absorbed moisture.

Claims (5)

Drying the residue obtained by squeezing the oil palm trunk and squeezing the sap; and
Separating the particulate solid from the residue after drying,
JIS method -K-7223 to produce a water-absorbing material comprising the particulate solids in the multi-porous structure that have a defined 10g or more water absorbency per 1g, the method for producing a water-absorbing material. Squeezing the felled oil palm trunk and drying the residue obtained by squeezing the sap; and
Separating the particulate solid from the residue after drying,
JIS method -K-7223 to produce a water-absorbing material comprising the particulate solids in the multi-porous structure that have a defined 10g or more water absorbency per 1g, the method for producing a water-absorbing material.
  The method for producing a water-absorbing material according to claim 1, wherein the particulate solid content is composed of a soft tissue of a woody part.   The method for producing a water-absorbing material according to claim 1 or 2, wherein the separation step of the particulate solid is separated from the acicular solid by sieving the residue after drying. The method for producing a water-absorbing material according to any one of claims 1 to 4, wherein the obtained water-absorbing material is used for a water-absorbing article for absorbing body fluid, water for soil improvement, water for civil engineering work or water for agriculture and horticulture.