DESCRIPTION

Title of Invention

THICKENER

Technical Field

[0001]

The present invention relates to a polymer compound (macromolecular compound) available from at least one of Corchorus capsularis L. and Corchorus aestuans L. The polymer compound is advantageously usable as a thickener for fossil resource extraction. The present application claims priority to Japanese Patent Application No. 2013-228651, filed in Japan on November 1, 2013, the entire contents of which are incorporated herein by reference.

Background Art

[0002]

Some fossil resources distributed as an oil or gas in a formation (geologic formation) lying 500 m to 4000 m

underground have not been recoverable by conventional technologies. However, these fossil resources can be extracted and recovered by a recently developed excavation technology. According to the novel excavation technology, excavation is performed horizontally along a formation including a fossil resource. A high-viscosity liquid containing water, a granular proppant such as sand grains, and chemical substances of various kinds is injected into the resulting borehole to cause fractures in the formation. The granular proppant is allowed to slip into the formed fractures to prevent the fractures from closing naturally, and thus the target fossil resource is continuously

recovered. The chemical substances for use herein include chemicals such as acids, antiseptic agents, and friction reducers; and, in combination with them, a thickener so as to allow the granular proppant to disperse stably.

[0003]

As the thickener for fossil resource extraction, guar gum (Patent Literature (PTL) 1) and carboxymethylcellulose

(CMC) have been used. These compounds have been used as thickeners for foodstuffs, are highly safe, and load a small burden on the environment. This reduces the risk of

pollution to drinking water. Disadvantageously, however, the guar gum suffers from competition in demand between the novel use (fossil resource extraction use) and already- existing uses (e.g., food or food additive uses). Also disadvantageously, the CMC has poor salt tolerance and has a sharply decreasing viscosity in the presence of a salt.

Citation List

Patent Literature

[0004]

PTL 1: Japanese Unexamined Patent Application Publication (JP-A) No. 2012-167273

Non Patent Literature

[0005]

NPL 1: Bulletin of Industrial Research Division, Mie Prefectural Science and Technology Promotion Center, No. 29 (2005)

Summary of Invention

Technical Problem

[0006]

Accordingly, an object of the present invention is to provide a polymer compound that is available from a plant as a raw material, can be easily extracted from the raw

material, is highly safe, loads a small burden on the environment, and offers an excellent thickening effect, where the raw material plant has been disposed as a waste.

Another object of the present invention is to provide a thickener for fossil resource extraction, including the polymer compound.

Yet another object of the present invention is to provide a fluid for fossil resource extraction, including the thickener for fossil resource extraction.

Solution to Problem

[0007]

After intensive investigations to achieve the objects, the inventors have obtained findings 1 to 5 as follows.

1. Corchorus capsularis L. and Corchorus aestuans L. contain large amounts of polymer compounds.

2. The stems of Corchorus capsularis L. and Corchorus aestuans L. are used as fibers as raw materials typically for fabrics, but leaves of these plants have been disposed as wastes and are thereby easily available.

3. Polymer compounds extracted from the leaves of Corchorus capsularis L. and/or Corchorus aestuans L. have different viscosities depending on extraction conditions, and a polymer compound having a high viscosity can be obtained under a specific condition.

4. The resulting polymer compound is highly

biodegradable and loads a small burden on the environment.

5. The polymer compound can stably maintain a

thickening effect even in the presence of a salt, namely, has excellent salt tolerance.

The present invention has been made based on these findings .

[0008]

Specifically, the present invention provides, in a first aspect, a polymer compound extracted from at least one of Corchorus capsularis L. and Corchorus aestuans L. The polymer compound has a shear viscosity of 0.2 Pa -s or more at a temperature of 25°C and a shear rate of 10 (1/s) in an aqueous solution containing 1 percent by weight of the polymer compound.

[0009]

The polymer compound may have a shear viscosity of 0.2 Pa -s or more at a temperature of 25°C and a shear rate of 10

(1/s) in an aqueous solution containing 10 percent by weight of NaCl and 1 percent by weight of the polymer compound.

[0010]

The polymer compound may have a solubility of 1 g or more per 100 g of water at a temperature of 25°C.

[0011]

The present invention provides, in a second aspect, a thickener for fossil resource extraction. The thickener includes the polymer compound.

[0012]

The present invention provides, in a third aspect, a fluid for fossil resource extraction. The fluid includes the thickener for fossil resource extraction.

[0013]

Specifically, the present invention relates to

followings .

[1] The present invention relates to the polymer compound extracted from at least one of Corchorus capsularis L. and Corchorus aestuans L. The polymer compound has a shear viscosity of 0.2 Pa-s or more at a temperature of 25°C and a shear rate of 10 (1/s) in an aqueous solution

containing 1 percent by weight of the polymer compound.

[2] The polymer compound according to [1] may have a shear viscosity of 0.2 Pa -s or more at a temperature of 25°C and a shear rate of 10 (1/s) in an aqueous solution

containing 10 percent by weight of an alkali metal halide and 1 percent by weight of the polymer compound.

[3] The polymer compound according to [1] may have a shear viscosity of 0.2 Pa-s or more at a temperature of 25°C and a shear rate of 10 (1/s) in an aqueous solution

containing 10 percent by weight of NaCl and 1 percent by weight of the polymer compound.

[4] The polymer compound according to any one of [1] to [3] may have a solubility of 1 g or more per 100 g of water at a temperature of 25°C and a pH of 7.0.

[5] The present invention also relates to the thickener for fossil resource extraction. The thickener includes the polymer compound according to any one of [1] to [4] .

[6] The thickener for fossil resource extraction according to [5] may contain the polymer compound in a content of 60 percent by weight or more based on the total amount of the thickener.

[7] The present invention further relates to the fluid for fossil resource extraction. The fluid includes the thickener for fossil resource extraction according to [5] or [6] .

[8] The fluid for fossil resource extraction according to [7] may contain the thickener in a content from 0.01 to 5 percent by weight based on the total amount of the fluid.

[9] The fluid for fossil resource extraction according to [7]· or [8] may contain the polymer compound according to any one of [1] to [4] in a content from 0.01 to 5 percent by weight based on the total amount of the fluid.

[10] The fluid for fossil resource extraction according to any one of [7] to [9] may include water, a granular proppant, and the thickener for fossil resource extraction.

[11] The present invention also relates to a method for extracting a fossil resource. The method uses the fluid for fossil resource extraction according to any one of [7] to [10] .

Advantageous Effects of Invention

[0014]

The polymer compound according to the present invention has a high viscosity and exhibits a more excellent

thickening effect particularly in a low concentration as compared with the guar gum.

The guar gum suffers from competition in demand between the novel use (fossil resource extraction use) and already- existing uses (e.g., food or food additive uses) . In contrast, the polymer compound according to the present invention can employ leaves of Corchorus capsularis L.

and/or Corchorus aestuans L. as a raw material, where the leaves have been conventionally disposed as wastes. The polymer compound is advantageous in availability of the raw material and can be produced from the raw material by a simple method. The polymer compound can therefore be inexpensively and stably provided.

In addition, the polymer compound according to the present invention is highly biodegradable and loads a small burden on the environment. This significantly reduces the risk of pollution to drinking water even when the polymer compound leaks out into the ground. The polymer compound has excellent salt tolerance and can continuously and stably exhibit a thickening effect even in the presence of a salt.

The polymer compound according to the present invention is therefore usable, instead of the guar gum and CMC, as a thickener typically for foodstuffs, cosmetics,

pharmaceuticals, and civil engineering materials (such as adhesive coating agents and concrete admixtures) and is advantageously usable particularly as a thickener for use in fossil resource extraction.

Brief Description of Drawings

[0015]

[Fig. 1] Fig. 1 is a graph indicating the shear viscosities (at 25°C) of polymer compounds obtained in examples and comparative examples each in a slurry

containing 1 percent by weight of the polymer compound.

[Fig. 2] Fig. 2 is a graph indicating the shear

viscosities (at 25°C) respectively of a polymer compound obtained in Example 1, and of a guar gum obtained in

Comparative Example 4, each in a slurry containing 0.2 percent by weight of the target compound.

[Fig. 3] Fig. 3 is a chart indicating the result of proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) of the polymer compound obtained in Example 1.

[Fig. 4] Fig. 4 is a chart indicating the result of infrared (IR) analysis of the polymer compound obtained in Example 1.

[Fig. 5] Fig. 5 is a chart indicating the result of thermogravimetry-differential thermal analysis (TG-DTA) of the polymer compound obtained in Example 1.

Description of Embodiments

[0016]

Polymer Compound

^' The polymer compound according to the present invention is prepared from at least one of Corchorus capsularis L. and Corchorus aestuans L. as a raw material.

[0017] The raw material Corchorus capsularis L. is an annual plant, is mainly produced in districts including India, Bangladesh, and other tropical zones, and has a scientific name of Corchorus capsularis L. Corchorus aestuans L. is an annual plant, is originated typically from India and Egypt, and has a scientific name of Corchorus aestuans L. All portions, such as stems and leaves, of these plants can be used without limitation. Among them, the leaves are

preferably used. This is because the leaves have been disposed as wastes, are thereby available as a raw material without competition with the already-existing uses and, when effectively used as resources, effectively contribute to suppressed global warming. Corchorus capsularis L. and Corchorus aestuans L. may be used in any form without limitation, such as a fresh one, dried one, or one after being subjected to a heat treatment typically by roasting. Among them, the raw material for use herein is preferably fresh one, or dried one after drying at a low temperature of 50 °C or lower. This may allow the polymer compound to have a more excellent thickening effect.

[0018]

The polymer compound according to the present invention is a hemicellulose extracted from cell-wall polysaccharides of at least one of Corchorus capsularis L. and Corchorus aestuans L. and is a polysaccharide containing at least a constitutional unit derived from a uronic acid. Part or all of acidic groups (carboxy groups) of the polysaccharide may form a salt. Specifically, such polymer compounds according to the present invention include a polysaccharide containing at least a constitutional unit derived from a uronic acid; and a compound corresponding to the polysaccharide, except with part or all of acidic groups (carboxy groups) of the polysaccharide forming a salt.

[0019]

The polymer compound according to the present invention is highly soluble in water and has a solubility in water of 1 g or more, and preferably 3 g or more, per 100 g of water at a temperature of 25 °C and a pH of 7.0. The polymer compound is therefore advantageously usable as a thickener for an aqueous composition.

[0020]

The polymer compound according to the present invention has a shear viscosity of 0.2 Pa-s or more, preferably 0.3 Pa -s or more, more preferably 0.4 Pa-s or more, particularly preferably 0.5 Pa-s or more, and most preferably 0.55 Pa-s or more at a temperature of 25°C and a shear rate of 10 (1/s) in an aqueous solution containing 1 percent by weight of the polymer compound. The upper limit of the shear viscosity is typically 3 Pa-s and preferably 2 Pa-s. The polymer compound according to the present invention therefore exhibits an excellent thickening effect. The term "shear viscosity" as used herein refers to a value measured by a method described in the examples (working examples) .

[0021]

Regular electrolyte polymer compounds (such as CMC) have a sharply decreasing viscosity in the presence of a salt (such as sodium chloride (NaCl) or another alkali metal halide) . In contrast, the polymer compound according to the present invention has excellent salt tolerance and has a shear viscosity of 0.2 Pa-s or more, preferably 0.4 Pa -s or more, and particularly preferably 0.5 Pa-s or more at a temperature of 25°C and a shear rate of 10 (1/s) in an agueous solution containing 10 percent by weight of a salt such as an alkali metal halide and 1 percent by weight of the polymer compound. Specifically, the shear viscosity is a shear viscosity in a salt-containing agueous solution containing 10 percent by weight of a salt (such as NaCl or another alkali metal halide) at a temperature of 25 °C and a shear rate of 10 (1/s). The salt-containing aqueous

solution is prepared by adding the salt to an aqueous solution containing 1 percent by weight of the polymer compound according to the present invention. The upper limit of the shear viscosity is typically 3 Pa-s, and preferably 2 Pa-s. In the presence of a salt, the polymer compound according to the present invention has not a decreased viscosity but rather an increased viscosity in an aqueous solution containing the polymer compound in a

concentration of 0.7 percent by weight or more. This is probably because, when present in the concentration, the polymer compound according to the present invention can form an intermolecularly bridged structure (crosslinked

structure) through the salt.

[0022]

In addition, the polymer compound according to the present invention is a plant-derived component, is highly biodegradable, and is eventually degraded to carbon dioxide and water by microorganisms in the natural world. The

polymer compound therefore loads a small burden on the environment and is highly safe.

[0023]

The polymer compound according to the present invention may be produced typically through Step 1 of alkaline

extraction and Step 2 of purification.

[0024]

The alkaline extraction in Step 1 may be performed by immersing the raw material in an alkaline aqueous solution. The immersion in an alkaline aqueous solution allows cell walls of Corchorus capsularis L. and/or Corchorus aestuans L. to swell and enables efficient extraction of a polymer compound having an excellent thickening effect. The alkaline aqueous solution is exemplified by aqueous

solutions respectively of sodium hydroxide, sodium

hydrogencarbonate , sodium carbonate, potassium hydroxide, barium hydroxide, and ammonia. Each of different alkaline aqueous solutions may be used alone or in combination.

[0025]

The alkaline aqueous solution for use in the extraction may have a pH of typically from about 8 to about 14, preferably from 9 to less than 13.5, particularly preferably from 9 to 13, and most preferably from 10 to 13. The alkaline aqueous solution for use in the extraction, if having a pH greater than the range, may tend to cause the extracted polymer compound to decompose, to thereby have a lower molecular weight, and to have a lower thickening effect. In contrast, the alkaline aqueous solution for use in the extraction, if having a pH less than the range, may hardly help the cell walls of Corchorus capsularis L. and/or Corchorus aestuans L. to swell and may cause lower

extraction efficiency of the polymer compound. At the completion of the alkaline extraction, the system (resulting mixture) may have a pH of typically from about 5.5 to about 13, preferably from 5.5 to 12, particularly preferably from 5.5 to 11, and most preferably from 6 to 10.

[0026]

For better extraction efficiency, the raw material is preferably subjected to a pulverization treatment before the extraction treatment.

[0027]

The extraction may be performed at a temperature of typically from about 10°C to about 90°C, preferably from 15°C to 60°C, and particularly preferably from 20°C to 40°C. The extraction, when performed at a temperature within the range, enables efficient extraction of a polymer compound from Corchorus capsularis L. and/or Corchorus aestuans L. and can prevent decomposition of the extracted polymer compound. The extraction may be performed for a time of typically one hour or longer and preferably from 2 to 5 hours .

[0028]

Step 2 is the step of isolating and purifying the polymer compound extracted in Step 1. The polymer compound may be isolated by one or more common processes for use in purification of polymer compounds. The processes are exemplified by filtration, concentration, precipitation, crystallization, and cooling-solidification. In a preferred embodiment according to the present invention, initially, an extract is separated and recovered from a mixture of the extract and a residue of the raw material. The term

"extract" herein refers to a liquid containing the extracted polymer compound as being dissolved therein. The separation and recovery may be performed typically by a process of subjecting the mixture to filtration; a process of

subjecting the mixture to centrifugal separation; or a process as a combination of them.

[0029]

The extract to be subjected to Step 2 preferably has a pH of from about 6 to about 7, and more specifically from 5.5 to 7.0. This pH range is preferred because the extract does not cause corrosion typically of facilities to be used, offers better handleability, and does not cause the

decomposition of the polymer compound, where the

decomposition is caused by exposure to an alkaline condition for a long time. Accordingly, the extract after the

completion of Step 1, when having a pH greater than 7, is preferably combined with an acid to be neutralized. The acid may be at least one selected from inorganic acids and organic acids. The inorganic acids are exemplified by hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid. The organic acids are. exemplified by acetic acid, formic acid, citric acid, oxalic acid, methanesulfonic acid, and p-toluenesulfonic acid. The end point of

neutralization may be determined typically with a pH meter or pH indicator paper.

[0030]

The filtration may be performed as natural filtration, or may be performed as vacuum filtration or pressure

filtration to increase the filtration rate. A membrane filter for use in the filtration is preferably one having a pore size of from about 10 to about 200 μιη. The centrifugal separation may be performed typically by centrifugally separating the mixture at 1000 rpm for 10 minutes. The filtration and/or centrifugal separation is preferably performed until the content of water-insoluble matter become 1 percent by weight or less (preferably 0.1 percent by weight or less). The filtration and/or centrifugal

separation may be performed once or repeated multiple times.

[0031]

The extract after being separated and recovered may be subjected further to a treatment such as concentration, precipitation, crystallization, and/or cooling- solidification to give a target polymer compound as a solid. Especially, in a preferred embodiment of the present

invention, the extract is poured into a poor solvent to allow the polymer compound to precipitate (or to

crystallize) , or, where necessary, is further allowed to reprecipitate or recrystallize .

[0032]

The poor solvent for use in the precipitation and reprecipitation is preferably an organic solvent having a lower solubility parameter (SP) as compared with water. Such organic solvent is exemplified by alcohols such as methanol, ethanol, propanol, 2-propanol, and butanol;

aliphatic hydrocarbons such as hexane, heptane, octane, and decane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylenes; ketones such as acetone, methyl ethyl ketone and cyclohexanone ;

esters such as methyl acetate, ethyl acetate, and butyl acetate; ethers such as ethyl ether, butyl ether, ethylene glycol dimethyl ether, and tetrahydrofuran; nitriles such as acetonitrile; amides such as N, N-dimethylformamide;

carboxylic acids such as acetic acid; halogenated

hydrocarbons such as methylene chloride and chloroform;

mixtures of these solvents; and mixtures of water and any of these solvents. Among them, a solvent mixture of water and an alcohol (e.g., methanol) is preferred herein, because the solvent mixture is inexpensively available, has a low boiling point, and can thereby be purified and reused at low cost.

[0033]

The solvent mixture of water and an alcohol preferably contains the alcohol in such a concentration that a

supernatant after precipitation (or reprecipitation) of the polymer compound contains the alcohol in a concentration of typically from about 40 to about 80 percent by weight, preferably from 50 to 70 percent by weight, and particularly preferably from 55 to 65 percent by weight. The solvent mixture, when containing the alcohol in a concentration within the range, allows the polymer compound to be highly purified with a low content of a low-molecular-weight

compound and to offer an excellent thickening effect, where the low-molecular-weight compound is formed by decomposition of the polymer compound.

[0034]

The polymer compound after precipitation or

reprecipitatxon may be deliquored typically by filtration and dried to give a powder. The drying may be performed by natural drying (air drying) , or artificial drying such as heat drying or vacuum drying.

[0035]

The method can efficiently give a polymer compound from the raw material, where the polymer compound offers an excellent thickening effect.

[0036]

Thickener for Fossil . Resource Extraction

The thickener for fossil resource extraction (or

thickening composition for fossil resource extraction) according to the present invention includes the polymer compound. As used herein the term "fossil resource" refers to a fossil resource that is distributed as an oil or gas and lies in a geologic formation 500 m to 4000 m underground. [0037]

The thickener for fossil resource extraction according to the present invention may contain the polymer compound in a content of 60 percent by weight or more, preferably 70 percent by weight or more, and particularly preferably 80 percent by weight or more, based on the total amount of the thickener. The thickener for fossil resource extraction according to the present invention may include the polymer compound alone or in combination with another component such as a thickening compound other than the polymer compound. In the latter case, the thickener may contain the other component in a content of typically less than 40 percent by weight, preferably 30 percent by weight or less,

particularly preferably 20 percent by weight or less, and most preferably 5 percent by weight or less.

[0038]

The thickener for fossil resource extraction according to the present invention contains the polymer compound having the above-described properties and has a viscosity equal to or higher than that of guar gum. The thickener for fossil resource extraction according to the present

invention is highly biodegradable and loads a small burden on the environment. This may reduce the risk of pollution to drinking water even when the thickener leaks out into the ground. The thickener has excellent salt tolerance and can continuously and stably exhibit a thickening effect even in the presence of a salt. The thickener is therefore

advantageously usable as a thickener for a fluid for use in extraction of fossil resources (i.e., a thickener for a fluid for fossil resource extraction) .

[0039]

Fluid for Fossil Resource Extraction

The fluid for fossil resource extraction according to the present invention is a fluid for use in extraction

(mining) of fossil resources and includes, as a thickener, the thickener for fossil resource extraction.

[0040]

The fluid for fossil resource extraction may contain the thickener in a content of typically from about 0.01 to about 5 percent by weight, based on the total amount (100 percent by weight) of the fluid, where the content is adjustable as needed. The fluid for fossil resource

extraction may contain the polymer compound in a content of typically from about 0.01 to about 5 percent by weight, based on the total amount (100 percent by weight) of the fluid, where the content is also adjustable as needed.

[0041]

The fluid for fossil resource extraction may contain one or more of other components in addition to the thickener for fossil resource extraction. Such other components are exemplified by water, a granular proppant (such as sand or silica sand), and various chemical substances. The chemical substances are exemplified by acids such as hydrochloric acid; antiseptic agents (preservatives); friction reducers; and pH adjusters. The fluid for fossil resource extraction may contain water and the granular proppant in a total content of typically 30 percent by weight or more (e.g., from about 30.00 to about 99.99 percent by weight),

preferably 50 percent by weight or more (e.g., from 50.00 to 99.97 percent by weight), particularly preferably 80 percent by weight or more (e.g., from 80.00 to 99.97 percent by weight), bead on the total amount (100 percent by weight) of the fluid.

[0042]

The fluid for fossil resource extraction according to the present invention contains the thickener for fossil resource extraction, can thereby maintain a suitable

viscosity even in the presence of a salt, and enables smooth and efficient extraction typically of a fossil resource that has not been recovered by conventional technologies.

Examples

[0043]

The present invention will be illustrated in further detail with reference to several examples below. It should be noted, however, that the examples are by no means intended to limit the scope of the invention.

[0044]

Example 1

Extraction

In a reactor, 300 g of pulverized, dried leaves of Corchorus capsularis L. were placed. The leaves were then combined with 2800 g of a 0.1 N NaOH aqueous solution (pH 13), followed by stirring. After stirring properly, the resulting mixture was left stand at room temperature (30°C) for 3 hours to perform an extraction treatment. The mixture at the completion of extraction had a pH of 9.4. The 0.1 N NaOH aqueous solution had been prepared by 50-fold dilution of a 5 N NaOH aqueous solution (supplied by ako Pure

Chemical Industries, Ltd.).

Neutralization

Thereafter 1400 g of ion-exchanged water were placed in the reactor, followed by a neutralization treatment with 160 g of 3.5 percent by weight hydrochloric acid. The

completion of neutralization was determined using a pH indicator paper.

Purification

The mixture obtained through the neutralization step was subjected to vacuum filtration using a vacuum pump with a nonwoven fabric (trade name T-ND 200T, supplied by NBC Meshtec Inc.) as a filter cloth to separate leaves (raw material residue) from a filtrate..

Next, the filtrate was added dropwise to a 75 percent by weight methanol aqueous solution in an amount four times the weight of the filtrate to give precipitates. The supernatant had a methanol concentration of 60 percent by weight .

The precipitates were deliquored properly, washed with a 75 percent by weight methanol aqueous solution in an amount one-fourth the weight of the filtrate, deliquored, and yielded 68 g of a wet powder. The wet powder was dried in a vacuum dryer at 40 °C in full vacuum overnight and yielded 12.0 g of a polymer compound (1) in a yield of 4.4 percent by weight. The polymer compound (1) had a

solubility of 5 g per 100 g of water at a temperature of 25°C and a pH of 7.0.

[0045]

The obtained polymer compound (1) was dissolved in water to a polymer compound concentration of 1 percent by weight, left stand at 30°C overnight, and yielded a slurry. The viscosity of the slurry was measured at 25°C using a rheometer. The results are given in Fig. 1.

Separately, the polymer compound (1) was dissolved in water to a polymer compound concentration of 0.2 percent by weight and yielded a slurry, and the viscosity of the slurry was measured at 25°C using a rheometer. The results are given in Fig. 2.

In addition, ¹ H-NMR, IR, and TG-DTA analyses of the polymer compound (1) were performed under conditions

mentioned below. The results are given in Figs. 3, 4, and 5.

Additionally, the polymer compound (1) was dissolved in water respectively to concentrations of 1.5, 1.0, and 0.7 percent by weight to give slurries. The slurries were each combined with NaCl to give NaCl-added slurries having a NaCl concentration of 10 percent by weight. The viscosities of the slurries and the NaCl-added slurries were measured using a rheometer to evaluate the salt tolerance. The results are given in Table 1.

[0046]

[Table 1]

TABLE 1

[0047]

The salt tolerance evaluation demonstrates that the polymer compound according to the present invention had not a decreased viscosity but rather an increased viscosity even in the presence of NaCl. This demonstrates that the polymer compound according to the present invention has excellent salt tolerance.

[0048]

Example 2

Extraction and neutralization were performed by the procedure of Example 1.

Purification

A mixture obtained through the neutralization step was subjected to vacuum filtration using a vacuum pump with a nonwoven fabric (trade name T-ND 200T, supplied by NBC Meshtec Inc.) as a filter cloth to separate a filtrate from residual leaves.

Next, the filtrate was added dropwise to 100 percent by weight methanol in an amount four times the weight of the filtrate to give precipitates. The supernatant had a methanol concentration of 80 percent by weight.

The precipitates were deliquored properly, washed with a 75 percent by weight methanol aqueous solution in an amount one-fourth the weight of the filtrate, deliquored, and yielded 160 g of a wet powder. The wet powder was dried in a vacuum dryer at 40 °C in full vacuum overnight and yielded 16.9 g of a polymer compound (2) in a yield of 5.1 percent by weight. The polymer compound (2) had a

solubility of 5 g per 100 g of water at a temperature of 25°C and a pH of 7.0.

[0049] By the procedure of Example 1, the obtained polymer compound (2) was treated to give a slurry having a

concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0050]

Example 3

Extraction

In a reactor, 10 g of pulverized, dried leaves of

Corchorus capsularis L. were placed. The leaves were then combined with 180 g of a 0.1 N NaOH agueous solution (pH 13), followed by an extraction treatment with stirring at 50°C for 2 hours. The mixture at the completion of extraction had a pH of 9.4. The 0.1 N NaOH aqueous solution had been prepared by 50-fold dilution of a 5 N NaOH aqueous solution (supplied by Wako Pure Chemical Industries, Ltd.).

Neutralization

The resulting mixture was subjected to a neutralization treatment with 4 g of 3.5 percent by weight hydrochloric acid. The completion of neutralization was determined using a pH indicator paper.

Purification

The mixture obtained through the neutralization step was subjected to vacuum filtration using a vacuum pump with a nonwoven fabric (trade name T-ND 200T, supplied by NBC Meshtec Inc.) as a filter cloth to separate a filtrate from residual leaves.

Next, the filtrate was added dropwise to 100 percent by weight methanol in an amount four times the weight of the filtrate to give precipitates. The supernatant had a methanol concentration of 80 percent by weight.

The precipitates were deliquored properly, washed with a 75 percent by weight methanol aqueous solution in an amount one-fourth the weight of the filtrate, and deliquored to give a wet powder. The wet powder was dried in a vacuum dryer at 40 °C in full vacuum overnight and yielded 0.17 g of a polymer compound (3) in a yield of 4.0 percent by weight. The polymer compound (3) had a solubility of 6 g per 100 g of water at a temperature of 25 °C and a pH of 7.0.

By the procedure of Example 1, the obtained polymer compound (3) was treated to give a slurry having a

concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0051]

Example 4

A polymer compound (4) was prepared by the procedure of Example 1, except for using an alkaline aqueous solution having a pH of 12.5 in the extraction step. The polymer compound (4) was obtained in a yield of 2.0 percent by weight and had a solubility of 4 g per 100 g of water at a temperature of 25 °C and a pH of 7.0. The mixture upon the completion of extraction had a pH of 8.4.

By the procedure of Example 1, the obtained polymer compound (4) was treated to give a slurry having a

concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0052]

Example 5

A polymer compound (5) was prepared by the procedure of Example 1, except for using an alkaline aqueous solution having a pH of 12 in the extraction step. The polymer compound (5) was prepared in a yield of 1.9 percent by weight and had a solubility of 4 g per 100 g of water at a temperature of 25 °C and a pH of 7.0. The mixture upon the completion of extraction had a pH of 6.4.

By the procedure of Example 1, the obtained polymer compound (5) was treated to give a slurry having a

concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0053]

Example 6

A polymer compound (6) was prepared by the procedure of Example 1, except for using an alkaline aqueous solution having a pH of 11 in the extraction step. The polymer compound (6) was prepared in a yield of 1.7 percent by weight and had a solubility of 4 g per 100 g of water at a temperature of 25 °C and a pH of 7.0. The mixture upon the completion of extraction had a pH of 5.8.

By the procedure of Example 1, the obtained polymer compound (6) was treated to give a slurry having a

concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0054]

Comparative Example 1

Hot Water Extraction

In a reactor, 10 g of pulverized, dried leaves of Corchorus capsularis L. were placed. The leaves were then combined with 180 g of ion-exchanged water (pH 7), stirred, and left stand to perform an extraction treatment at 50 °C for 2 hours. The mixture at the completion of extraction had a pH of 5.7.

Purification

The mixture obtained through the neutralization step was subjected to vacuum filtration using a vacuum pump with a nonwoven fabric (trade name T-ND 200T, supplied by NBC Meshtec Inc.) as a filter cloth to separate a filtrate from residual leaves.

Next, the filtrate was added dropwise to 100 percent by weight methanol in an amount four times the weight of the filtrate to give precipitates. The supernatant had a methanol concentration of 80 percent by weight. The precipitates were deliquored properly, washed with a 75 percent by weight methanol aqueous solution in an amount one-fourth the weight of the filtrate, and deliquored to give a wet powder. The wet powder was dried in a vacuum dryer at 40 °C in full vacuum overnight and yielded 0.67 g of a polymer compound (7) in a yield of 6.7 percent by weight.

The obtained polymer compound (7) was treated to give a slurry having a concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0055]

Comparative Example 2

Extraction

In a reactor, 10 g of pulverized, dried leaves of

Corchorus capsularis L. were placed. The leaves were then combined with 180 g of a 0.5 N NaOH aqueous solution (pH 13.5) and subjected to an extraction treatment with stirring at 50 °C for 2 hours. The mixture at the completion of extraction had a pH of 12.9. The 0.5 N NaOH aqueous

solution had been prepared by 10-fold dilution of a 5 N NaOH aqueous solution (supplied by Wako Pure Chemical Industries, Ltd. ) .

Neutralization

The mixture was then subjected to a neutralization treatment with 85 g of 3.5 percent by weight hydrochloric acid. The completion of neutralization was determined using a pH indicator paper.

Purification

The mixture obtained through the neutralization step was subjected to vacuum filtration using a vacuum pump with a nonwoven fabric (trade name T-ND 200T, supplied by NBC eshtec Inc.) as a filter cloth to separate a filtrate from residual leaves.

Next, the filtrate was added dropwise to 100 percent by weight methanol in an amount four times the weight of the filtrate to give precipitates. The supernatant had a methanol concentration of 80 percent by weight.

The precipitates were deliquored properly, washed with a 75 percent by weight methanol aqueous solution in an amount one-fourth the weight of the filtrate, and deliquored to give a wet powder. The wet powder was dried in a vacuum dryer at 40 °C in full vacuum overnight and yielded 0.53 g of a polymer compound (8) in a yield of 5.3 percent by weight.

The obtained polymer compound (8) was treated to give a slurry having a concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0056]

Comparative Example 3

This comparative example was performed according to the experimental method described in NPL 1.

Delipidation

In a reactor were placed 20 g of dried leaves of Tossa jute (mulukhiya) (Corchorus olitorius L. ) . The leaves were then combined with 50 mL of chloroform (supplied by Wako Pure Chemical Industries, Ltd. ) and 50 mL of methanol

(supplied by Wako Pure Chemical Industries, Ltd.), followed by delipidation with stirring at 50°C for 30 minutes. The leaves were separated from a filtrate, placed again in the reactor, and combined with 50 mL of chloroform (supplied by Wako Pure Chemical Industries, Ltd.) and 50 mL of methanol (supplied by Wako Pure Chemical Industries, Ltd.), followed by delipidation with stirring at 50°C for 30 minutes.

The leaves were then separated from a filtrate, placed in a reactor, combined with 50 mL of diethyl ether (supplied by Wako Pure Chemical Industries, Ltd.) and 50 mL of ethanol (supplied by Wako Pure Chemical Industries, Ltd.), followed by delipidation with stirring at 50°C for 30 minutes. The leaves were separated from a filtrate, placed again in the reactor, and combined with 50 mL of diethyl ether (supplied by Wako Pure Chemical Industries, Ltd.) and 50 mL of

ethanol (supplied by Wako Pure Chemical Industries, Ltd.), followed by delipidation with stirring at 50°C for 30 minutes. The resulting leaves were further subjected to a drying treatment and yielded 18 g of dried leaves. The separation of the leaves from a filtrate was performed by vacuum filtration using a vacuum pump with a nonwoven fabric (trade name T-ND 200T, supplied by NBC Meshtec Inc.) as a filter cloth.

Extraction

In a reactor were placed 18 g of the obtained dried leaves. The leaves were then combined with 400 g of a 0.5 N NaOH aqueous solution (pH 13.5), followed by an extraction treatment at 50 °C for one hour. The mixture at the

completion of extraction had a pH of 13.0. The 0.5 N NaOH aqueous solution had been prepared by 10-fold dilution of a 5 N NaOH aqueous solution supplied by Wako Pure Chemical Industries, Ltd.

Neutralization

Thereafter the mixture was subjected to a

neutralization treatment with 120 g of 3.5 percent by weight hydrochloric acid. A polymer precipitated upon the addition of excessive hydrochloric acid. The mixture was therefore combined again with the NaOH aqueous solution to adjust the pH, and the completion of neutralization was determined at a pH of 6.

Purification

The mixture obtained through the neutralization step was subjected to vacuum filtration using a vacuum pump with a nonwoven fabric (trade name T-ND 200T, supplied by NBC Meshtec Inc.) as a filter cloth to separate a filtrate from residual leaves.

Next, the filtrate was added dropwise to 100 percent by weight ethanol in an amount two times the weight of the filtrate to give precipitates.

The precipitates were deliquored properly, washed with two portions of 70 g of a 75 percent by weight ethanol aqueous solution, and deliquored to give a wet powder. The wet powder was freeze-dried and yielded 0.7 g of a polymer compound (9) in a yield of 3.9 percent by weight.

The obtained polymer compound (9) was treated to give a slurry having a concentration of 1 percent by weight, and the viscosity of the slurry was measured. The results are given in Fig. 1.

[0057]

Comparative Example 4

Guar gum derived from guar cluster bean {Cyamopsis tetragonoloba) as a Leguminous plant was prepared as a product under the trade name of IGGUAR FG-88L (supplied by INDIA GLYCOLS LIMITED) . The guar gum was treated to give a slurry having a guar gum concentration of 0.2 percent by weight, and the .viscosity of the slurry was measured using a rheometer. The 'results are given in Fig. 2.

[0058]

Analyses Conditions Viscosity

Measuring device: rheometer (trade name MCR-301, supplied by Anton Paar GmbH)

Atmosphere: N ₂ atmosphere

Temperature: 25°C

Shear rate: 0.1 to 1000 (1/s)

Jig used in measurement: 25 mm-diameter cone-and-plate [0059]

^" " ^" H-NMR

An aliquot (3 mg) of the polymer compound (1) obtained in Example 1 was combined with 1 g of deuterium oxide (D ₂ 0) as a solvent and left stand overnight. A sample (0.7 mL) was sampled from the resulting aqueous solution, placed in a sample tube, and subjected to ^{^} H-NMR measurement.

Measurement conditions were as follows.

Device: JNM-A500 supplied by JEOL Ltd.

Probe: 5 mm-diameter

Measurement temperature: 80 °C

Number of scans: 32

[0060]

TG-DTA

An aliquot (8 mg) of the polymer compound (1) obtained in Example 1 was sampled on a quartz pan and subjected to TG-DTA measurement. Measurement conditions were as follows. Measuring device: EXSTAR 6300 supplied by SII Nano Technology Inc. (now Hitachi High-Tech Science Corporation) Atmosphere: air

Temperature range: 50°C to 900°C

[0061]

IR

An aliquot (1 mg) of the polymer compound (1) obtained in Example 1 and 10 mg of KBr were placed in a mortar, and mixed and ground using a pestle. The ground sample was placed in a mold, press-molded, and subjected to an infrared (IR) measurement. Measurement conditions were as follows.

Device: HORIBA FT-720 Spectrophotometer supplied by HORIBA, Ltd.

Number of scans: 16

Measurement range: 400 to 4000 cm ^-1

Measurement method: KBr method

[0062]

The above results demonstrate that the polymer

compounds obtained in the examples had higher viscosities as compared with the polymer compounds obtained in the

comparative examples. This demonstrates that the polymer compounds according to the present invention are

advantageously usable, instead of guar gum, as a thickener for use typically in foodstuffs, cosmetics, pharmaceuticals, civil engineering materials (e.g., adhesive coating agents and concrete admixtures), and fossil resource extraction. Industrial Applicability

[0063]

The polymer compounds according to the present

invention exhibit an excellent thickening effect. The polymer compounds can be simply produced from a raw material that is easily available. The polymer compounds have excellent salt tolerance and can continuously and stably exhibit a thickening effect even in the presence of a salt. In addition, the polymer compounds are highly biodegradable and load a small burden on the environment.

The polymer compounds according to the present

invention have the properties in combination, are

advantageously usable each as a thickener typically for foodstuffs, cosmetics, pharmaceuticals, and civil

engineering materials (e.g., adhesive coating agents and concrete admixtures ), and are particularly advantageously usable each in fossil resource extraction as a thickener for a fluid for fossil resource extraction.