WO2023003291A1 - Method for preparing natural biodegradable superabsorbent polymer and use thereof - Google Patents

Abstract

The present invention relates to a method for preparing a natural biodegradable superabsorbent polymer and use thereof. The absorption power of a superabsorbent polymer prepared according to the preparation method of the present invention is at a level sufficient to meet a reference value, and the superabsorbent polymer has a more significant biodegradation effect than conventional synthetic superabsorbent polymers as a result of biodegradation experiments, and thus can be effectively used in hygiene products for the purpose of absorbing moisture and the like.

Description

Manufacturing method of natural biodegradable super absorbent and use thereof

The present invention relates to a method for preparing a natural biodegradable super absorbent and a use thereof.

Superabsorbent polymer (SAP) refers to a cross-linked polymer capable of absorbing a large amount of liquid, swelling to form a hydrogel, and retaining the absorbed liquid. Representative types of synthetic polymer absorbers include crosslinked hydroalkyl (meth)acrylic acid, N-vinylpyrrolidone, ethyl oxide, acrylamide, (meth)acrylic acid, poly(vinyl alcohol), and crosslinked poly(acrylic acid) (PAA ) dominates the market.

There are various sanitary products such as women's sanitary napkins, diapers for infants and children, and most of them use petrochemical-based polymer absorbers that are harmful to the human body. Since sanitary products made of the petrochemical-based polymer absorber cannot be biodegraded after use, it causes various serious environmental and economic problems in the landfill or incineration process when discarded. / It has been very active both internally and externally, but compared to existing chemical products, the performance of the product is not only very low in water retention and absorbency under pressure, but also causes heat, skin soreness, and itching caused by harmful substances.

On the other hand, chitin is the second most abundant polymer after cellulose in the natural environment, and is a polymer in which N-acetyl-glucosamine [poly-b-(1-4)-N-acetyl-D-glucosamine] is continuously bonded. to be. It is also the main component of the shells of crustaceans such as crayfish, crabs, and shrimps, the exoskeleton of insects such as scarabs, cicadas, and grasshoppers, the skeletons of mollusks such as squid, and the cell walls of fungi such as molds, yeasts, and mushrooms. Since chitin is synthesized in various living organisms, it is also considered a biopolymer. It has chemical properties that are insoluble in water and is a water-soluble material called Chitosan that can be applied for various purposes through a chemical process called deacetylation. Transformed.

Chitin has a structure similar to that of cellulose in which 2-acetamino-2-deoxy-D-glucose is β-(1,4) bonded, and the hydroxyl group at the C-2 position is substituted with an acetamino group, and C3-OH… The intermolecular bonds of C5 and NH… O=C and C6-OH... O=C is stabilized by intermolecular hydrogen bonds. Depending on the arrangement of molecular chains in the crystal structure, there are three stereoisomers of α-, β-, and γ-. α-chitin is the most dense form with two chains stacked antiparallel to each other, and β-chitin is a form in which chains are arranged parallel to each other, and C ₃ -OH ^... O ₅ between the same chains is different from each other. Interchain -NH and -CO groups form hydrogen bonds, but it is less dense than α-chitin. γ-chitin has a downward arrangement of one unit chain for every two pyranose units. In nature, α-chitin is most widely distributed, and it is especially contained in the epidermis of arthropods. β-Chitin exists in the state of crystalline hydrate, and is a poorly arranged material that allows water to permeate easily between the chains of the crystal lattice. α-chitin is present in the cysts of arthropods, mushrooms and Entamoea , and β-chitin can be obtained from the bones of Loligo . Finally, γ-chitin is present in the cocoons of beetles and the stomach walls of Loligo . The structure of this γ-chitin consists of two antiparallel chains and one parallel chain.

Chitin is used as an ingredient in fertilizers to increase crop yields. Fertilizers containing chitin are organic materials, have low toxicity and are known to increase yield. It is also known to help harvest by increasing the activity of soil microorganisms and enzymes when treated with chitin-containing fertilizer. Crabs, shrimp, etc. have been materials from which chitin can be obtained from the past, and chitin obtained from them has long been used as a variety of food additives. Finely powdered chitin is used as a food additive and improves the flavor of food. In addition, it is added to food to function as an emulsifier. Chitin is also used in medicine and is known to reduce cholesterol when consumed by humans. It is also used as a material for suture thread used in surgical operations. Chitin is known to aid in the healing process of wounds and is naturally biodegradable.

As an absorber-related technology, Korean Patent Publication No. 2018-0028244 discloses a method for manufacturing a natural polymer absorber capable of absorbing moisture, and Korean Patent No. 2052113 discloses red algae extract and water-soluble chitin polymer as active ingredients. An absorbent with enhanced antibacterial activity and a method for producing the same have been disclosed, but the method for producing the natural biodegradable super absorbent of the present invention and its use have not yet been disclosed.

The present invention has been derived from the above needs, and the present invention provides a method for producing a natural biodegradable super absorbent and its use, and the absorbent produced according to the manufacturing method of the present invention has a sufficient level to meet the standard value. And, as a result of the biodegradation experiment, the present invention was completed by confirming that there is a significant biodegradation effect than the conventional synthetic absorber.

In order to achieve the above object, the present invention (1) based on 100 parts by weight of chitin, after adding 100 to 500 parts by weight of water, 50 to 150 parts by weight of a phosphoric acid compound and 100 to 300 parts by weight of a urea-based compound, 20 Reacting at ~40°C for 3~9 hours, washing and first drying;

(2) heat-treating the chitin dried in step (1) at 140-180° C. for 10-100 minutes, then washing the heat-treated chitin with a caustic soda solution to make it gel, and washing with water to swell;

(3) fibrillating chitin using a high-speed grinder, homogenizer, or super mass collidor so that the chitin swollen in step (2) has a width of 3 nm to 3 μm;

(4) secondarily drying the chitin fibrillated in step (3) at 30 to 100° C.; and

(5) preparing a powder having a diameter of 10 to 3,000 μm by pulverizing the secondarily dried chitin fibrils in step (4);

In addition, the present invention provides a sanitary product comprising the natural biodegradable super absorbent produced by the manufacturing method of the present invention.

The present invention relates to a method for producing a natural biodegradable super absorbent and its use, and the absorbent produced according to the manufacturing method of the present invention has a sufficient level of absorption to meet the standard value, and as a result of biodegradation experiments, a remarkable biodegradation effect than conventional synthetic absorbents. there is

1 is a comparative photograph of the high absorbents of Example 2 and Comparative Example 1 of the present invention before biodegradation (Day 0) and Day 7.

The present invention (1) based on 100 parts by weight of chitin, after adding 100 to 500 parts by weight of water, 50 to 150 parts by weight of a phosphoric acid compound and 100 to 300 parts by weight of a urea-based compound, 3 to 9 parts by weight at 20 to 40 ℃ reacting for a period of time, washing and primary drying;

(2) heat-treating the chitin dried in step (1) at 140-180° C. for 10-100 minutes, then washing the heat-treated chitin with a caustic soda solution to make it gel, and washing with water to swell;

(3) fibrillating chitin using a high-speed grinder, homogenizer, or super mass collidor so that the chitin swollen in step (2) has a width of 3 nm to 3 μm;

(4) secondarily drying the chitin fibrillated in step (3) at 30 to 100° C.; and

(5) preparing a powder having a diameter of 10 to 3,000 μm by pulverizing the secondarily dried chitin fibrils in step (4);

The chitin is an N-acetylglucosamine [poly-b-(1-4)-N-acetyl-D-glucosamine] polymer, preferably α-chitin or β-chitin derived from crustaceans such as crab shells, and more Preferred is β-chitin, but is not limited thereto.

In the step (1), the phosphoric acid-based compound is preferably any one selected from monobasic ammonium phosphate, dibasic ammonium phosphate ((NH ₄ ) ₂ HPO ₄ ) and sodium dihydrogen phosphate, more preferably the first Ammonium phosphate, but is not limited thereto.

In the step (1), the urea-based compound is preferably any one selected from urea, thio urea, and dimethyl urea, and more preferably urea, but is not limited thereto.

Immediately before fibrillation in step (3), CMC (carboxy methyl cellulose), citric acid, konjac, alginic acid, carrageenan, pentane, cyclopentane, hexane, cyclohexane ( At least one selected from among cyclohexane, heptane, cycloheptane, butanol, and isobutanol may be added, and the width of the fibril in step (3) is 3 to 100 nm on average. It is characterized by

Between steps (3) and (4), with respect to 100 parts by weight of the fibrillated chitin obtained in step (3), any one selected from oxidized starch, cationic starch, phosphate starch, carrageenan, konjac, and alginic acid It is preferable to further include, but is not limited thereto.

In the present invention, 'cationic starch' can be prepared by treating corn starch, potato starch, tapioca starch, wheat starch, sweet potato starch, etc. with a cationizing agent, and is a conventional method in the art, for example, the method described in US Patent 4127563. can be obtained according to A cationizing agent refers to a substance in which one end of a molecule has a reactive group capable of bonding with a hydroxyl group on a starch molecule and the other end has a cationic group, such as derivatives containing a tertiary amino group and a quaternary ammonium ether group. , and quaternary ammonium-based protonating agents such as 3-chloro-2-hydroxytrimethylammonium chloride and 2,3-epoxypropyltrimethylammonium chloride are preferred.

Between steps (3) and (4), with respect to 100 parts by weight of the fibrillated chitin obtained in step (3), epichlorohydrin, glyoxal and maleic acid It is preferable to further include, but is not limited thereto.

Secondary drying in the manufacturing method of the present invention is drying by heat treatment; Solvent drying by adding any one organic solvent selected from methanol, ethanol, isopropanol, butanol, acetone and toluene; freeze drying; and vacuum drying; It is preferable to dry any one selected from, but is not limited thereto.

In addition, it relates to a sanitary product comprising a natural biodegradable super absorbent produced by the manufacturing method of the present invention.

The sanitary product is preferably any one selected from diapers for infants, diapers for adults, panty liners, sanitary napkins, and tampons, but is not limited thereto.

Hereinafter, the present invention will be described in more detail using examples. These examples are only for explaining the present invention in more detail, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

Example 1

(1) Immerse 100 g of β-chitin grains with a diameter of 2 to 5 mm in 250 g of distilled water solution in which 75 g of ammonium monophosphate and 200 g of urea are dissolved, react at 25 ° C for 6 hours, and remove the β- chitin grains. and dried at 30°C.

(2) After treating the dried β-chitin in step (1) at 150° C. for 60 minutes, it was washed with a caustic soda solution, and the washed β-chitin was washed again with water to prepare a swollen gel.

(3) Carboxymethyl cellulose (CMC) was added to the swollen β-chitin of step (2) in an amount of 3% by weight, and pulverized using a supermass colloider so that the width of β-chitin was 1 μm or less on average. and fibrillated.

(4) After step (3), the obtained β-chitin fibrils were dried at 60°C.

(5) After step (4), the dried β-chitin fibrils from which moisture was removed were pulverized to prepare a biodegradable superabsorbent in powder form having a diameter of 10 to 1,000 μm.

Example 2

In step (3) of Example 1, the rest of the steps are the same as in Example 1 except that CMC was not added and chitin was pulverized and fibrillated to an average width of 200 nm using a supermass colloider. As a method, a biodegradable super absorbent in the form of a powder having a size of 10 to 1,000 μm was prepared.

Example 3

In step (3) of Example 1, except for fibrillation by adding 3% by weight of citric acid instead of CMC, the rest of the steps are the same as in Example 1, and the biodegradable superabsorbent in powder form with a size of 10 to 1,000 μm was manufactured.

Example 4

In step (4) of Example 1, after adding 20% by weight of cationic starch (corn starch with a quaternary ammonium substitution degree of 0.9) to the chitin fibrils obtained in step (3), Except for drying at 60 ° C., the remaining steps were prepared in the same manner as in Example 1 to prepare a biodegradable super absorbent in the form of a powder having a size of 10 to 1,000 μm.

Example 5

In step (3) of Example 1, chitin fibrils were pulverized and fibrillated so that the average width of chitin was 200 nm using a supermass colloider without adding CMC, and in step (4) chitin fibrils were 98 The remaining steps are the same as in Example 1, except that chitin fibrils are dried by slowly adding methanol at 500 revolutions per minute in methanol at 10 to 1,000 μm to obtain a powdery biodegradable superabsorbent. manufactured.

Example 6

In step (3) of Example 1, except for fibrillation by adding 5% by weight of pentane instead of CMC, the remaining steps are the same as in Example 1, and the biodegradable superabsorbent in powder form having a size of 10 to 1,000 μm was manufactured.

Comparative Example 1

A synthetic superabsorbent polymer (SAP) collected by separating and collecting oversized pant-type diapers of company Y on the market was used.

Comparative Example 2

DS228 X2 synthetic super absorbent (Danson Technology, China) was purchased and used.

Comparative Example 3

After diluting the β-chitin grains in water at a concentration of 2%, they were placed in a supermass colloider and pulverized and fibrillated until the width of β-chitin fibrils was less than 100 nm. Thereafter, the obtained β-chitin fibrils were dried at 60° C., and pulverized in the same manner as in step (5) of Example 1 to prepare a biodegradable superabsorbent in powder form having a diameter of 10 to 1,000 μm. .

Experimental Example 1. Comparative test of absorption capacity

The super absorbent was placed in a filter cloth, immersed in saline for 30 minutes, and dehydrated using centrifugal force together with the filter cloth, and then the weight (g) of the super absorbent was measured.

Saline water absorbency confirmation result of Examples 1 to 6 and Comparative Examples 1 to 3

	Weight of initial absorber (g)	after saline absorption Weight of absorber (g)	Water absorption rate of absorber (%)
Example 1	1.0	18.4	1,740
Example 2	1.0	20.6	1,960
Example 3	1.0	15.8	1,480
Example 4	1.0	21.2	2020
Example 5	1.0	17.3	1,630
Example 6	1.0	16.8	1,580
Comparative Example 1	1.0	24.1	2,310
Comparative Example 2	1.0	20.7	1,970
Comparative Example 3	1.0	5.8	480

In Table 1, the water absorption of the absorbent was calculated as (weight of the absorbent after saline absorption - weight of the initial absorbent) × 100. As a result, as shown in Table 1, the water absorption of the absorbent of Examples 1 to 6 of the present invention (% ) was found to be 1,480 to 2,020%, and the commercially available synthetic super absorbents of Comparative Examples 1 and 2 were found to be 1,970 to 2,310%. In general, in the case of a high absorbent material having an absorption rate (%) of 1,000% or more, it is known that there is no problem in using it in the production of products such as commercial diapers. Therefore, it can be seen that the natural super absorbent has a slightly lower saline water absorption rate than the synthetic super absorbent, but is sufficient for use as an absorbent.

In particular, in the case of Comparative Example 3, which was fibrillated without performing treatment steps such as phosphoric acid-based compound treatment and heat treatment according to the production method of the present invention, the absorption rate of absorbing saline was very high compared to Examples 1 to 6 of the present invention. low was found. That is, although general chitin fibrils can also absorb water or saline, they are inappropriate for use as a high absorbent that requires an absorption rate of 10 times or more (>1,000%).

In addition, in the case of the natural super absorbent according to the present invention, it is possible to solve the problem of microplastics by biodegrading at room temperature, and various chemicals that can be included in the synthetic super absorbent (certification standard EL324: 2017 of the Ministry of Environment, Annex D. Allergy, carcinogens) list) has the advantage that it is not fundamentally included.

Experimental Example 2. Comparison of changes in mass due to biodegradation of absorbers

Synthetic superabsorbents (synthetic SAP1-2; Comparative Examples 1-2), natural superabsorbents of the present invention (Bio-SAP1-6; Examples 1-6) and chitin nanofibrils obtained by pulverizing chitin into nanofibrils (Comparative Example 3) 1 g each was taken, sufficiently absorbed in water, and put in an oven at 30 ° C. to measure the change in weight due to biodegradation for 30 days. In order to measure the initial dry weight of the super absorbent, after washing the super absorbent using filter paper, putting it in an oven at 100 ° C to dry it, and after 7 days, 13 days, 20 days, and 30 days, respectively, the super absorbent After washing on filter paper, it was dried and the weight of each was measured.

As a result, synthetic SAP1 and synthetic SAP2 had moisture content of 9.88% and 10.21%, respectively, and dry weights of 0.912 g (day 0) and 0.898 g (day 0), respectively. The bio-SAP according to has a water content of 13 to 14.5%, and the relative weight (%) after biodegradation is shown in Table 2 based on the dry weight after removing the water content as 100%, respectively.

The values measured on the 7th to 30th days are the measurements of the amount remaining after biodegradation as low molecular weight substances are removed by biodegradation. Confirmed. From these results, it can be seen that the superabsorbent of the present invention has excellent biodegradability similar to that of chitin fibrils (Comparative Example 3), and the weight change of the synthetic superabsorbent in contrast to this is about 30% of the initial Other than weight loss, little change in weight occurred.

That is, the natural superabsorbent of the present invention was biodegraded at room temperature and turned yellow after 7 days (FIG. 1), and was almost completely decomposed within 3 weeks and its weight decreased, but the synthetic superabsorbent changed its shape or shape after the 7th day. It was confirmed that there was no change in weight.

Relative mass (%) according to biodegradation of synthetic superabsorbents (synthetic SAP1-3; Comparative Examples 1-3) and natural superabsorbents of the present invention (Bio-SAP1-6; Examples 1-6)

	Day 0	Day 7	Day 13	Day 20	Day 30
Example 1 (Bio SAP1)	100.0	48.2	15.4	12.8	8.5
Example 2 (Bio SAP2)	100.0	50.7	17.6	17.6	9.5
Example 3 (Bio SAP3)	100.0	52.3	18.5	14.3	8.2
Example 4 (Bio SAP4)	100.0	50.3	15.5	13.3	7.2
Example 5 (Bio SAP5)	100.0	49.3	15.8	13.8	8.2
Example 6 (Bio SAP6)	100.0	50.9	16.6	14.6	8.5
Comparative Example 1 (synthetic SAP1)	100.0	75.2	69.5	69.5	68.1
Comparative Example 2 (synthetic SAP2)	100.0	77.5	70.5	70.2	70.2
Comparative Example 3 (chitin fibrils)	100.0	50.2	16.3	15.6	8.3

Claims (11)

1. (1) Based on 100 parts by weight of chitin, 100 to 500 parts by weight of water, 50 to 150 parts by weight of a phosphoric acid compound, and 100 to 300 parts by weight of a urea-based compound are added, followed by reaction at 20 to 40° C. for 3 to 9 hours. washing, washing and primary drying;

   (2) heat-treating the chitin dried in step (1) at 140-180° C. for 10-100 minutes, then washing the heat-treated chitin with a caustic soda solution to make it gel, and washing with water to swell;

   (3) fibrillating chitin using a high-speed grinder, homogenizer, or super mass collidor so that the chitin swollen in step (2) has a width of 3 nm to 3 μm;

   (4) secondarily drying the chitin fibrillated in step (3) at 30 to 100° C.; and

   (5) preparing a powder having a diameter of 10 to 3,000 μm by pulverizing the secondarily dried chitin fibrils in step (4);
2. The method of claim 1, wherein the chitin in step (1) is α-chitin or β-chitin.
3. The method of claim 1, wherein the phosphoric acid-based compound in step (1) is any one selected from monobasic ammonium phosphate, dibasic ammonium phosphate ((NH ₄ ) ₂ HPO ₄ ) and sodium dihydrogen phosphate. A method for producing a natural biodegradable superabsorbent.
4. The method of claim 1, wherein the urea-based compound in step (1) is any one selected from urea, thio urea and dimethyl urea.
5. The method of claim 1, immediately before fibrillation in step (3), CMC (carboxy methyl cellulose), citric acid, konjac, alginic acid, carrageenan, pentane, cyclopentane, hexane ( hexane), cyclohexane, heptane, cycloheptane, butanol, and isobutanol, and then fibrillating the swollen chitin. Method for producing a natural biodegradable superabsorbent.
6. The method of claim 1, wherein the fibrils in step (3) have an average width of 3 to 100 nm.
7. The method of claim 1, between the step (3) and the step (4), based on 100 parts by weight of the fibrillated chitin obtained in the step (3), oxidized starch, cationic starch, phosphate starch, carrageenan, Adding any one selected from konjac and alginic acid in an amount of 1 to 40 parts by weight.
8. The method of claim 1, between the step (3) and the step (4), based on 100 parts by weight of the fibrillated chitin obtained in the step (3), epichlorohydrin (epichlorohydrin), glyoxal ( Method for producing a natural biodegradable superabsorbent further comprising the step of adding 1 to 10 parts by weight of any one selected from glyoxal and maleic acid.
9. The method of claim 1, wherein the secondary drying is drying by heat treatment; Solvent drying by adding any one organic solvent selected from methanol, ethanol, isopropanol, butanol, acetone and toluene; freeze drying; and vacuum drying; Method for producing a natural biodegradable super absorbent, characterized in that the drying of any one selected from.
10. A sanitary product comprising a natural biodegradable super absorbent produced by the method of any one of claims 1 to 9.
11. [Claim 11] The sanitary product of claim 10, wherein the sanitary product is any one sanitary product selected from among diapers for babies, diapers for adults, panty liners, sanitary napkins, and tampons.

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