KR102555843B1 - Multifunctional hydrogel for soil conditioner, soil conditioner comprising same, and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a multifunctional hydrogel having various physical properties such as water absorption rate, a soil improving agent including the same, and a manufacturing method thereof. The method for producing a multifunctional hydrogel for a soil conditioner of the present invention includes the steps of obtaining a crosslinked hydrogel; Drying and pulverizing to prepare a hydrogel for a soil improver by a method comprising the step of obtaining a particulate hydrogel, (a) the content of the monomer; (b) composition ratio of monomers; (c) A particulate hydrogel having a desired water absorption rate selectively in the range of 90 times to 300 times or more can be prepared by controlling at least one of the temperatures during hot air drying within a predetermined range. Since the multifunctional hydrogel and the soil improving agent containing the same according to the present invention can have a desired water absorption rate selectively in the range of 90 to 300 times or more, different moisture levels are obtained depending on the growth stage and type of the plant and the cultivation environment. It can be used for a variety of applications that require the environment.

Description

Multifunctional hydrogel for soil conditioner, soil conditioner containing the same, and manufacturing method thereof {Multifunctional hydrogel for soil conditioner, soil conditioner comprising same, and method for manufacturing the same}

The present invention relates to a hydrogel for a soil improver, and more particularly to a multifunctional hydrogel having various physical properties such as water absorption, a soil improver including the same, and a manufacturing method thereof.

In the natural environment, soil has limitations in maintaining water retention and fertility, so in most cases, artificially supplying water and nutrients is necessary for crop production. In particular, the need for artificial water and nutrient supply is greater in areas where precipitation is not constant or insufficient, and in soils with poor nutrients. However, artificial water supply is also limited, so it is difficult for plants to grow in desert areas or in areas where people are difficult to access. As a result, desertification and devastation of the soil are further progressing, leading to a problem in which areas where food resources can be produced and forests are reduced.

Soil improvers are products that improve the physicochemical properties of soil to make it suitable for plant growth. Zeolite, perlite, lime fertilizer, compost, organic fertilizer, etc. are used as soil conditioners. In particular, products containing moisture-absorbing polymers as a main component are used as products that help maintain moisture in the soil. A representative moisture-absorbing polymer product is TerraCottem™ (hereinafter referred to as "Terracottem").

Terracottem is a product that is a mixture of hydrogel, a hydrophilic network polymer, inorganic nutrients, growth promoters, and electrolyte materials, and can supply moisture and nutrients to the soil for a long time. Water-absorbent polymer products such as Terracottem allow a wide variety of plants to grow luxuriantly in areas with inconsistent or severely insufficient rainfall and in poor and nutrient-poor soils. Since these water-absorbing polymer products for soil improving agents play an important role in improving the rhizosphere environment in agriculture, various researches are being conducted at home and abroad for product development, and there are many related patents (KR 10-2014-0036947, KR 10-2018-0033327, US 7652080 B2, etc.).

When manufacturing hydrogel, which is a key component of water-absorbing polymer products for soil conditioners, organic crosslinking agents are generally used. Since organic crosslinking agents are mostly substances that do not decompose within a short period of time, there is a toxicity problem due to excessive use or concentration. In order to solve this problem, the present applicant developed a water-absorbing polymer in which a cross-linking site was formed using laponite instead of an organic cross-linking agent and applied for application number 10-2020-0132257 (Public Patent No. 10-2022-0048883: hereinafter referred to as 'Prior Application Patent'). referred to as).

On the other hand, depending on the type, growth stage, and cultivation environment of the plant, the required soil moisture or nutrient conditions vary. However, conventional soil improving agents containing water-absorbing polymers are mostly commercialized as a single product with fixed physical properties such as water absorption rate (water holding capacity). It has been previously known that physical properties can be adjusted to some extent by adjusting the mixing ratio of monomers and crosslinking agent content during hydrogel synthesis. However, if the ratio is greatly adjusted, there is also a problem that adversely affects other physical properties such as degree of crosslinking and stability. Therefore, most of them did not make products with various moisture absorption rates, but focused on making one product optimized through fine adjustment within a narrow range. Even in the case of Terracotem, which is used the most at home and abroad, a single product with fixed physical and physicochemical properties is on the market in Korea.

Even in the prior application patent of the present applicant, it is described that the water absorption rate (swelling degree) varies depending on the ratio of the monomers potassium acrylate (KA) and N,N'-dimethylacrylamide (DMAAm) or the amount of laponite used. Specifically, in the weight ratio of KA:DMAAm, the water absorption rate (swelling degree) increases as KA increases, and shows a similar value from a maximum of 4:6, and the water absorption rate decreases as the laponite content increases. However, when laponite is used at 3% by weight, which is a desirable level in terms of crosslinking degree, the water absorption rate does not reach 300 times (300 g/g) or more even when the ratio of KA:DMAAm is adjusted to the maximum value (FIG. 6). However, since the water absorption rate of Comparative Example (TC), which is a commercial product, is at the level of 200 g/g, in the prior application patent, when laponite is used at 3% by weight, the KA:DMAAm weight ratio is adjusted to about 3:7 to 4:6 to obtain about 220 higher than TC. Since it can show a water absorption rate of ~250 g/g, it was possible to manufacture a single product optimized to a competitive level.

As such, conventional hydrogels for soil improvers do not meet various physical properties required differently depending on the growth stage, type, and cultivation environment of plants. On the other hand, recent environmental changes such as global abnormal temperatures, changes in precipitation, and progress of desertification further increase the need for development of multifunctional hydrogels that can be applied to various environments in various regions and soil conditioners containing them.

Korean Patent Publication No. 10-2014-0036947 Korean Patent Publication No. 10-2018-0033327 US 7652080 B2 US/6831122 B2 DE/102009034137 A1 EP/0156786 B1

The present invention is a multifunctional hydrogel having various physical properties such as water absorption rate and a manufacturing method thereof so that it can be applied in various ways according to the growth stage, type and cultivation environment of plants. Its object is to provide a soil improver containing the same. In particular, the present invention relates to a multifunctional hydrogel having a water absorption rate ranging from 90 to 300 times or more in an acrylamide-acrylate polymer-based hydrogel crosslinked with laponite, a method for preparing the same, and a soil improver including the same It aims to provide

In order to achieve the above object, in the present invention,

An acrylate monomer and dimethylacrylamide (DMAAm) were added in a ratio of 0.2:9.8 to 3.5:6.5 to a 2-4% by weight laponite dispersion in which laponite was dispersed in water, and an initiator was added. and cross-linking to obtain a cross-linked hydrogel;

The cross-linked hydrogel is first dried at 90 to 150 ° C. to remove moisture, dipped in distilled water to remove unreacted monomers, and then dried again at 90 to 150 ° C. Preparing a hydrogel for a soil improver by a method comprising the step of obtaining,

By controlling any one or more of (a), (b), and (c) below within the range described, obtaining a particulate hydrogel having a desired water absorption selectively in the range of 90 times to 300 times or more by weight Characterized in that, it provides a method for producing a multifunctional hydrogel for a soil improver.

(a) Increasing the water absorption rate by increasing the content of the monomer in which the acrylate monomer and dimethylacrylamide are combined in the range of 15 to 35% by weight in the dispersion

(b) Increase the water absorption rate by increasing the content of the acrylate monomer within the range of 0.2:9.8 to 3.5:6.5 in the ratio of the acrylate monomer and dimethylacrylamide

(c) The first and second hot air drying reduces the moisture absorption rate by lowering the temperature in the range of 90 to 120 ° C.

The manufacturing method,

It may further include adjusting the hardness together by adjusting any one or more of the above (a), (b) and below (d) within the described range.

(d) increasing the hardness by increasing the content of laponite in the range of 2 to 4% by weight in the dispersion

In a preferred embodiment of the manufacturing method,

The ratio of the acrylate monomer and dimethylacrylamide is set to 2.5:7.5 to 3.5:6.5, and the content of the combined monomer of the acrylate monomer and dimethylacrylamide is 15% by weight or more and less than 25% by weight in the dispersion,

The crosslinked hydrogel was firstly dried with hot air at 100 to 150 ° C for 2 to 48 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 100 to 150 ° C for 2 to 48 hours and pulverized 300 times. A particulate hydrogel having a higher water absorption rate can be obtained.

In another preferred embodiment of the manufacturing method,

The ratio of the acrylate monomer and dimethylacrylamide is from 1.5:8.5 to less than 2.5:7.5, and the content of the monomer in which the acrylate monomer and dimethylacrylamide are combined is 25 to 35% by weight in the dispersion,

The crosslinked hydrogel was first dried with hot air at 100 to 150 ° C for 2 to 48 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 100 to 150 ° C for 2 to 48 hours and pulverized. It is possible to obtain a particulate hydrogel having a water absorption rate of more than twice that.

In another preferred embodiment of the manufacturing method,

The ratio of the acrylate monomer and dimethylacrylamide is from 0.5:9.5 to less than 2.5:7.5, and the content of the monomer in which the acrylate monomer and dimethylacrylamide are combined is 15 to 35% by weight in the dispersion,

The crosslinked hydrogel was first dried with hot air at 90 to 120 ° C for 1 to 40 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 90 to 120 ° C for 1 to 40 hours and pulverized. A particulate hydrogel with a water absorption rate of 300 times in pears can be obtained.

In another preferred embodiment of the manufacturing method,

The ratio of the acrylate monomer and dimethylacrylamide is from 0.2:9.8 to less than 0.5:9.5, and the content of the monomer in which the acrylate monomer and dimethylacrylamide are combined is 15 to 35% by weight in the dispersion,

The crosslinked hydrogel was first dried with hot air at 90 to 120 ° C for 1 to 36 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 90 to 120 ° C for 1 to 36 hours and pulverized. A particulate hydrogel with a water absorption rate of 160 times in pears can be obtained.

In addition, in a preferred embodiment of the present invention,

15 wt% or more and less than 25 wt% of a monomer in a ratio of acrylate monomer to dimethylacrylamide of 2.5:7.5 to 3.5:6.5 was added to a 2 to 4 wt% laponite dispersion, crosslinked, dried, and pulverized to obtain , It provides a soil improving agent comprising a particulate hydrogel having a water absorption rate of 300 times or more.

In another preferred embodiment of the present invention,

300 obtained by adding 25 to 35% by weight of a monomer in which the ratio of acrylate monomer to dimethylacrylamide from 1.5:8.5 to less than 2.5:7.5 was added to a 2 to 4% by weight laponite dispersion, crosslinked, and then dried and pulverized. It provides a soil improving agent comprising a particulate hydrogel having a water absorption rate of more than twice.

In another preferred embodiment of the present invention,

160 obtained by adding 15 to 35% by weight of a monomer with a ratio of acrylate monomer to dimethylacrylamide from 0.5:9.5 to less than 2.5:7.5 to a 2 to 4% by weight laponite dispersion, crosslinking, drying and grinding It provides a soil improving agent comprising a particulate hydrogel having a water absorption rate of less than 300 times in pears.

In another preferred embodiment of the present invention,

To a 2-4% by weight laponite dispersion, 15 to 35% by weight of a monomer in which the ratio of acrylate monomer to dimethylacrylamide is from 0.2:9.8 to less than 0.5:9.5 is added, crosslinked, dried and pulverized to obtain a 90 Provided is a soil improving agent comprising a particulate hydrogel having a water absorption rate of less than 160 times in pears.

In the present invention, it is possible to provide a multifunctional hydrogel having a desired water absorption rate selectively in the range of 90 times to 300 times or more. In particular, in the present invention, it is an acrylamide-acrylate polymer-based hydrogel crosslinked with laponite, which is suitable for raising seedlings, preventing desertification, areas where precipitation is not constant or insufficient, and improving soils with poor nutrients. It is possible to provide a particulate hydrogel having a high water absorption rate. In addition, in the present invention, particulate hydrogels having a water absorption rate of 160 to less than 300 times that can be used universally, including for differentiation, and particles having a water absorption rate of 90 to less than 160 times suitable for soil cultivation type hydrogels can be provided.

The soil improving agent of the present invention including the multifunctional hydrogel as described above can appropriately supply moisture and nutrients to the soil according to the growth stage and type of the plant and the cultivation environment. In particular, a soil improving agent containing a multifunctional hydrogel having a high water absorption rate of 300 times or more can prevent desertification and rebuild barren land, minimize plant damage due to abnormal climate, and improve soil that retains moisture for a long time. . In addition, the soil improver of the present invention, which includes a multifunctional hydrogel whose water absorption rate is adjusted to suit each use, can properly maintain the moisture environment at a level necessary for the growth stage and type of each plant and the cultivation environment. There is an effect of making maintenance convenient, reducing required manpower, and reducing production and management costs.

1a, 1b, 1c, and 1d are graphs showing the water absorption rate of the hydrogel prepared by changing the monomer content and ratio as a result of measuring the water absorption rate of the particulate hydrogel prepared in Example 1.
Figure 2 is a result of measuring the water absorption rate of the particulate hydrogel prepared in Example 2, and is a graph of water content comparison by content (20 wt%, 30 wt%) of DMAAm and KA.
Figure 3 is a result of measuring the water absorption of the particulate hydrogel prepared in Example 3, the monomer content is 20 wt% and the monomer ratio is KA:DMAAm = 0.25: 9.75, 2:8, 3:7.
Figure 4 is a result of measuring the water absorption of the particulate hydrogel prepared in Example 4, the monomer content is 20 wt% and the monomer ratio is KA:DMAAm = 3:7.
Figures 5a and 5b are the results of measuring the drying time according to the change in temperature, 5a is the drying time at 80 ℃, 5b is the drying time at 110 ℃.
Figures 6a and 6b are the results of measuring the swelling behavior according to temperature change, 6a is a graph of water absorption rate by time according to temperature, and 6b is a graph of final water absorption rate according to temperature.
7 is a result of measuring swelling behavior according to pH.
8 is a fracture strain measurement result.
9 is an Elastic modulus measurement result.
10 is a result of soil weight change rate after irrigation for each hydrogel treatment concentration.
Figure 11a is the result of soil weight change rate during daily irrigation for each hydrogel treatment concentration.
Figure 11b is the result of soil weight change rate when irrigation once every 3 days for each hydrogel treatment concentration.
Figure 11c is the result of soil weight change rate when irrigation once every 6 days for each hydrogel treatment concentration.
12 is a result of measuring root length during daily irrigation for each hydrogel treatment concentration.
13 is a result of measuring dry weight during daily irrigation for each hydrogel treatment concentration.
14 is a harvest photograph during daily irrigation for each hydrogel treatment concentration.
15 is the result of measuring the root length when watering once every 3 days for each hydrogel treatment concentration.
16 is a result of measuring dry weight when irrigation once every 3 days for each hydrogel treatment concentration.
17 is a harvest photograph when irrigation once every 3 days for each hydrogel treatment concentration.
18 is a result of measuring root length when watering once every 6 days for each hydrogel treatment concentration.
19 is a result of measuring dry weight when irrigation once every 6 days for each hydrogel treatment concentration.
20 is a harvest photograph when irrigation once every 6 days for each hydrogel treatment concentration.

The method for producing a multifunctional hydrogel for a soil conditioner of the present invention,

obtaining a cross-linked hydrogel; Drying and pulverizing to prepare a hydrogel for a soil improver by a method comprising the step of obtaining a particulate hydrogel, (a) the content of the monomer; (b) composition ratio of monomers; (c) A particulate hydrogel having a desired water absorption rate selectively in the range of 90 to 300 times or more is prepared by adjusting at least one of the temperatures during hot air drying within a predetermined range.

The soil improving agent of the present invention includes a particulate hydrogel having a desired water absorption rate ranging from 90 times to 300 times or more.

Each will be described in detail below.

1. For soil conditioner versatility of hydrogel manufacturing method

(One) bridged hydrogel steps to get

First, laponite is dispersed in water to make a 2-4% by weight laponite dispersion. Laponite is a nano-sheet clay, and in the present invention, a crosslinking point is formed by using laponite instead of an organic crosslinking agent. When laponite is dispersed in water, a certain distance is maintained between the laponites due to electrostatic attraction. Due to this dispersion characteristic, a hydrogel having cross-linked points with laponite can form a uniform cross-linked structure. Since the content of laponite in the dispersion has an inverse correlation with the water absorption rate of the finally obtained particulate hydrogel, the water absorption rate can be increased by lowering the laponite content in the dispersion. However, if the laponite content is maintained at 1.5% by weight or less, it is not desirable in terms of various physical properties such as crosslinking degree, hardness, stable crosslinking structure, etc. It is preferable to set it as weight%, and especially about 3 weight% is preferable. In the present invention, the water absorption rate can be adjusted to a desired range by adjusting other factors while maintaining the laforite content at 2 to 4% by weight.

When laponite is dispersed in water, it is preferable to use water from which impurities such as ions, particles, organic matter, microorganisms, and gases are removed. Therefore, 'water' here is defined as a concept including all water from which impurities are removed, such as purified water, distilled water, and pure water, and those skilled in the art may select and use an appropriate water from among water from which impurities are removed.

When dispersing laponite, a dispersing agent may be used together if necessary. In a preferred embodiment of the present invention, laponite and a dispersing agent are added to distilled water and the laponite is completely dispersed to prepare a 2-4% by weight laponite dispersion. The dispersant is not particularly limited, but for example, sodium pyrophosphate tetrabasic (Na4P2O7, hereinafter referred to as 'SPT') may be used.

To the obtained laponite dispersion, monomers such as acrylate monomer and dimethylacrylamide (DMAAm) were added, and an initiator was added to cause a cross-linking reaction. Acrylate monomer and dimethylacrylamide are added in a ratio of 0.2:9.8 to 3.5:6.5.

As the acrylate monomer, potassium acrylate (Potassium acrylate; hereinafter referred to as 'KA') may be used. The initiator is not particularly limited, but preferably potassium persulfate (hereinafter referred to as 'KPS') may be used.

During the crosslinking reaction, preferably, a catalyst may be further used. A catalyst is added to the laponite dispersion together with the above initiator. Preferably, N,N,N',N'-tetramethylenediamine (hereinafter referred to as 'TEMED') can be used as the catalyst. In a preferred embodiment, a catalyst is added to the laponite dispersion along with an initiator, and a crosslinking reaction is performed at 30 to 50° C. for 12 to 36 hours.

In this step, a crosslinked hydrogel is obtained by the above crosslinking reaction.

(2) particle type hydrogel steps to get

First, the crosslinked hydrogel obtained in the above step is first dried with hot air at 90 to 150 ° C to remove moisture, and then immersed in distilled water to remove unreacted monomers. Then, after secondary hot air drying at 90 ~ 150 ° C., it is pulverized to obtain a particulate hydrogel.

Immersion in distilled water is to remove residual substances such as unreacted monomers, and generally, all residual substances are removed by sufficiently immersing for 1 to 3 days. At this time, those skilled in the art may use water such as purified water or pure water instead of distilled water. Here, 'distilled water' is defined to refer to all forms of water from which impurities contained in water have been removed, including purified water and pure water.

After sufficiently immersing in distilled water, it is dried again with secondary hot air to completely remove moisture, and then pulverized to obtain a particulate hydrogel.

The hot air drying temperature in this step is an important factor affecting the water absorption rate of the finally obtained particulate hydrogel.

(3) water absorption rate control

In the above step, by adjusting at least one of the following (a), (b), and (c) within the range described, the finally obtained particulate hydrogel has a desired water absorption rate in the range of 90 to 300 times or more by weight. It can be selectively adjusted to have.

In the present invention, the 'water absorption rate' may be expressed as 'swelling degree' or 'water retention amount' or 'water content', and is defined as the maximum amount of water that the hydrogel can absorb on a weight basis. The water absorption rate can be calculated by the following formula by putting the hydrogel in distilled water and immersing it sufficiently until it absorbs moisture to the maximum, and then measuring the weight of the hydrogel and comparing it with before water absorption.

[Equation 1]

(Where, W _s is the weight of the hydrogel that has absorbed maximum moisture, and W _d is the weight of the particulate hydrogel before absorbing moisture)

(a) The water absorption rate is increased by increasing the content of the monomer in which the acrylate monomer and dimethylacrylamide are combined in the range of 15 to 35% by weight in the dispersion.

When the content of the monomer is less than 15% by weight, the water absorption rate is low and it is not preferable in terms of physical properties such as hardness. In addition, when it exceeds 35% by weight, an inverse correlation may appear and the water absorption rate may be lowered. Therefore, the content of the monomer is increased or decreased within the range of 15 to 35% by weight, which has a positive correlation with the water absorption rate, so as to reach the desired moisture absorption rate.

(b) The water absorption rate is increased by increasing the content of the acrylate monomer within the range of 0.2:9.8 to 3.5:6.5 in the ratio of the acrylate monomer and dimethylacrylamide.

Increasing the ratio of the acrylate monomer among the monomers increases the water absorption rate. As the content of the ionic monomer, acrylate monomer (KA) increases, the water absorption space widens due to the repulsion of ions in the hydrogel, resulting in an increase in the water absorption rate. is thought to increase. As the ratio of the acrylate monomer increases, the water absorption rate of the hydrogel increases, but considering the physical and chemical properties such as appropriate degree of crosslinking, crosslinking stability, and hardness, it is not desirable to use the acrylate monomer at a ratio of 4:6 or more. . In the present invention, while adjusting the ratio of acrylate monomer and dimethylacrylamide within the range of 0.2:9.8 to 3.5:6.5, the water absorption rate can be increased by as much as 300 times (by weight) or more.

(c) Lowering the temperature within the range of 90 ~ 120 ℃ during the first and second hot air drying to reduce the water absorption rate. Even if it is raised to 120 ° C or higher, there is no significant difference between 120 ° C and the water absorption rate, so the water absorption rate can be adjusted by adjusting the temperature within the range of 90 ° C below 120 ° C. However, since the temperature range from more than 120 ° C to 150 ° C has the advantage of shortening the drying time compared to 120 ° C, those skilled in the art can select it appropriately.

(4) Hardness control

The hardness can be adjusted together by adjusting any one or more of the above (a), (b) and below (d) within the described range.

As can be seen in the test examples below, the hardness shows a tendency to decrease under conditions in which the water absorption rate increases. Therefore, the hardness can be increased by adjusting the conditions (a) and (b) opposite to the conditions in which the water absorption rate increases within the described range.

(d) The hardness may be increased by increasing the content of laponite in the range of 2 to 4% by weight in the dispersion. As the content of laponite increases, the crosslinking degree increases and the hardness increases, but there is a problem in that the water absorption rate decreases. Therefore, it is preferable to adjust the hardness by adjusting the content within the above range while maintaining an appropriate degree of crosslinking, stable crosslinking structure, and the like.

Hereinafter, a preferred embodiment of preparing a particulate hydrogel having a specific desired water absorption rate by adjusting the water absorption rate as described above will be described.

Particle-type hydrogel with more than 300 times water absorption

In the above production method, the ratio of acrylate monomer and dimethylacrylamide is set to 2.5:7.5 to 3.5:6.5, and the content of the monomer combined with the acrylate monomer and dimethylacrylamide is 15% by weight or more and less than 25% by weight in the dispersion. A crosslinked hydrogel is obtained in the same manner as in the step of obtaining the crosslinked hydrogel, except for the above.

Then, the crosslinked hydrogel was first dried with hot air at 100 to 150 ° C for 2 to 48 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 100 to 150 ° C for 2 to 48 hours and pulverized. , obtaining a particulate hydrogel with a water absorption rate of 300 times or more.

In this way, it is possible to obtain a particulate hydrogel with a water absorption rate of 300 times or more by weight, and up to 700 times or more is possible within this range. However, even if the water absorption rate is too high, there is a negative effect affecting the stability of the stratum structure, so it is generally desirable to obtain a particulate hydrogel having a water absorption rate of up to 300 to 700 times (by weight).

Particle-type hydrogel with more than 300 times water absorption

It is another preferred embodiment for producing a particulate hydrogel having a water absorption rate of 300 times or more.

In the above manufacturing method, the ratio of acrylate monomer and dimethylacrylamide is set from 1.5:8.5 to less than 2.5:7.5, and the content of the monomers in which the acrylate monomer and dimethylacrylamide are combined is set to 25 to 35% by weight in the dispersion. Except for this, the crosslinked hydrogel is obtained by performing the same steps as in the step of obtaining the crosslinked hydrogel.

Then, the crosslinked hydrogel was first dried with hot air at 100 to 150 ° C for 2 to 48 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 100 to 150 ° C for 2 to 48 hours and pulverized. , obtaining a particulate hydrogel with a water absorption rate of 300 times or more.

In this method, as in the above preferred embodiment, it is possible to obtain a particulate hydrogel having a water absorption of 300 to 700 times or more by weight, and it is generally preferable to obtain a particulate hydrogel having a water absorption rate of 300 to 700 times. .

Particulate hydrogel with 160 to 300 times water absorption

In the above manufacturing method, the ratio of acrylate monomer and dimethylacrylamide is set to 0.5:9.5 to less than 2.5:6.5, and the content of the monomers in which the acrylate monomer and dimethylacrylamide are combined is set to 15 to 35% by weight in the dispersion. Except for that, the crosslinked hydrogel is obtained in the same manner as in the step of obtaining the crosslinked hydrogel.

Then, the crosslinked hydrogel was first dried with hot air at 90 to 120 ° C for 1 to 40 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 90 to 120 ° C for 1 to 40 hours and pulverized. , to obtain a particulate hydrogel with a water absorption rate of 160 to 300 times.

Particulate hydrogel with 90 to 160 times water absorption

In the above production method, the ratio of acrylate monomer and dimethylacrylamide is set from 0.2:9.8 to less than 0.5:9.5, and the content of the monomers in which the acrylate monomer and dimethylacrylamide are combined is set to 15 to 35% by weight in the dispersion. Except for this, the crosslinked hydrogel is obtained by performing the same steps as in the step of obtaining the crosslinked hydrogel.

Then, the crosslinked hydrogel was first dried with hot air at 90 to 120 ° C for 1 to 36 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 90 to 120 ° C for 1 to 36 hours and pulverized. , to obtain a particulate hydrogel with a water absorption rate of 90 to 160 times.

Hereinafter, a soil improving agent comprising the multifunctional hydrogel prepared as described above will be described.

300 times higher water absorption hydrogel Soil improver containing

To a 2 to 4% by weight laponite dispersion, 15% by weight or more and less than 25% by weight of a monomer with a ratio of acrylate monomer to dimethylacrylamide of 2.5:7.5 to 3.5:6.5 was added, crosslinked, and then dried and pulverized. , It is a soil improving agent containing a particulate hydrogel having a water absorption rate of 300 times or more.

Alternatively, 25 to 35% by weight of a monomer in which the ratio of acrylate monomer to dimethylacrylamide is from 1.5:8.5 to less than 2.5:7.5 is added to 2 to 4% by weight of laponite dispersion, crosslinked, dried and pulverized. , It is a soil improver containing a particulate hydrogel having a water absorption rate of 300 times (300 g/g) or more.

Description of each configuration is omitted because it is the same as the manufacturing method above. the same below

Soil improvers containing hydrogels with a high water absorption rate of 300 g / g or more can be used for various purposes that require long-term moisture retention in the soil, including applications such as preventing desertification, rebuilding desolate lands, and minimizing plant damage due to abnormal climate. can In particular, it is suitable for raising seedlings in the growth stage of plants. Raising seedlings is a task that requires careful water management due to the small size of individual seedling trays, so it has a high water absorption rate to reduce manpower and costs for water management work, shorten shipping days, and produce high-quality seedlings with stable water supply. For this purpose, it is preferable to use a soil improver having a high water absorption rate of 300 times or more.

It has a moisture absorption rate of 160 to less than 300 times. hydrogel Soil improver containing

160 obtained by adding 15 to 35% by weight of a monomer with a ratio of acrylate monomer to dimethylacrylamide from 0.5:9.5 to less than 2.5:7.5 to a 2 to 4% by weight laponite dispersion, crosslinking, drying and grinding It is a soil improving agent containing a particulate hydrogel having a water absorption rate of less than 300 times in pears.

Soil improvers containing hydrogels with a water absorption rate of 160 times or more and less than 300 times have a water absorption rate similar to those of existing commercially available soil conditioners, so they can be used universally for various purposes. suitable for use For differentiation, it is preferable to apply a hydrogel that can be used universally because the size of individual pots is diverse and the fields of use such as flowers and vegetables are diverse. The hydrogel with a water absorption rate of 160 to 300 g/g provides stable water supply and micropores in various flower pots, helping the roots to root and grow quickly.

90 to less than 160 times water absorption hydrogel Soil improver containing

To a 2-4% by weight laponite dispersion, 15-35% by weight of a monomer with an acrylate monomer to dimethylacrylamide ratio of 0.2:9.8 to less than 0.5:9.5 was added, crosslinked, dried and pulverized to obtain a 90 It is a soil improving agent containing a particulate hydrogel having a water absorption rate of less than 160 times in pears.

A soil improver containing a hydrogel having a water absorption rate of 90 to less than 160 times is particularly suitable for soil cultivation as a plant growth stage. Soil must be accompanied by plowing work, so a hydrogel with a higher hardness than other uses is required so that it can not be destroyed by plowing work in the open field soil, and a relatively low water absorption rate of 90 to 160 g/g is suitable. .

The soil improver of the present invention having various water absorption rates mentioned above may further include various materials required by plants or soil, such as inorganic nutrients, growth promoters, and electrolyte materials, in addition to the multifunctional hydrogel. Soil conditioners further containing these substances can continuously supply nutrients along with moisture to soil and plants.

Hereinafter, the present invention will be described in more detail through specific examples. Since these examples illustrate the present invention, the scope of the present invention is not limited thereto.

<Example 1>

Preparation of particulate hydrogels

1) Production of potassium acrylate (KA) is prepared by the same method as the embodiment of the prior application patent of the present applicant, Publication Patent Publication No. 10-2022-0048883.

2) Add laponite at 3% by weight to distilled water together with a dispersant. Tetrabasic sodium pyrophosphate (SPT) was used as the dispersant, and was added so that the weight ratio of laponite:SPT was 1:00768. Potassium acrylate (KA) and dimethylacrylamide (DMAAm), which are monomers, were added to the dispersion in which laponite was completely dispersed at different ratios of KA:DMAAm of 0:10, 0.25:9.75, 0.5:9.5, and 0.75:9.25, respectively. . In addition, the total amount of monomers in which KA and DMAAm were combined for each ratio was added in three types of 20% by weight, 30% by weight, and 40% by weight in the dispersion. In the case of 30% by weight and 40% by weight of the total monomer content, a test group with a ratio of KA:DMAAm of 1:9 was added. Therefore, a total of 14 test plots were made. Potassium persulfate (KPS) as an initiator and N,N,N',N'-tetramethylenediamine (TEMED) as an initiator were added thereto, mixed, sealed, and crosslinked at 40°C for 24 hours to obtain a crosslinked hydrogel. .

3) The crosslinked hydrogel was thoroughly dried with hot air at about 100 ° C. for 24 hours to ensure that no moisture remained, and then immersed in distilled water for 24 hours to remove remaining foreign substances such as unreacted monomers. After crushing the swollen hydrogel finely, it was dried sufficiently with hot air at about 100 ° C. so that no moisture remained, and then pulverized using a mixer to prepare a particulate hydrogel.

<Test Example 1>

Moisture absorption rate measurement

Water absorption was measured for the particulate hydrogel prepared in Example 1. The prepared particulate hydrogel and distilled water were put into a falcon tube for each test section and sufficiently immersed until maximum moisture was absorbed, and then the weight of the hydrogel that absorbed moisture was measured. Compared with the weight of the particulate hydrogel before absorbing moisture, the water absorption rate was calculated by the following formula. The results are shown in Figures 1a, 1b, 1c, 1d and Table 1.

[Equation 1]

(Where, W _s is the weight of the hydrogel that has absorbed maximum moisture, and W _d is the weight of the particulate hydrogel before absorbing moisture)

Figure 1a is the result of 30% by weight of the total monomer content, 1b is the result of 40% by weight, 1c is the result of 20% by weight. 1d is the result of comparing 14 test plots together.

When the total monomer content was increased from 20wt% to 30wt%, the water absorption rate was found to increase, but at 40wt%, the water absorption rate tended to decrease. This is because the water absorption rate of a general hydrogel is judged to increase as the monomer increases, although the water absorption rate decreases due to the increase of the binding chain as the monomer increases.

The water absorption rate according to the change in the ratio of KA:DMAAm showed that the water absorption rate increased as the content of KA increased in all test groups.

Table 1 below shows the total monomer content and water absorption rate by monomer ratio.

monomer content Monomer ratio KA:DMAAm 0:10 0.25:0.75 0.5:9.5 0.75:9.25 20wt% 17.84 ± 0.32 98.05 ± 2.49 166.15 ± 5.23 209.12 ± 4.41 30wt% 19.16 ± 1.00 106.68 ± 2.87 169.99 ± 3.66 227.29 ± 3.12 40wt% 23.42 ± 2.09 89.33 ± 2.04 140.75 ± 9.03 169.75 ± 7.50

<Example 2>

Preparation of particulate hydrogels

The ratio of KA:DMAAm was 0:10, 1:9, and 2:8, respectively, and the total content of the monomers combining KA and DMAAm was 20% by weight and 30% by weight in the dispersion. A total of 6 test groups were prepared. Except for the above, a particulate hydrogel was prepared in the same manner as in Example 1.

<Test Example 2>

Moisture absorption rate measurement

Water absorption was measured in the same manner as in Test Example 1 for the particulate hydrogel of each test group prepared in Example 2. The results are shown in FIG. 2 . When the total content of the monomer was 30wt% than when it was 20wt%, the water absorption rate was increased. When the ratio of KA:DMAAm was set to 2:8, the water absorption rate was about 240 g/g at 20 wt% of the total monomer content, and about 400 g/g at the total content of monomers of 30 wt%.

<Example 3>

Preparation of particulate hydrogels

The ratio of KA:DMAAm was 0.25:9.75, 2:8, and 3:7, respectively, and the total content of the monomers of KA and DMAAm was 20% by weight in the dispersion, and a total of three test groups were prepared and at about 120 ° C. A particulate hydrogel was prepared in the same manner as in Example 1, except that hot air drying was performed for about 24 hours .

<Test Example 3>

Moisture absorption rate measurement

Water absorption was measured in the same manner as in Test Example 1 for the particulate hydrogel of each test group prepared in Example 3. The results are shown in FIG. 3 .

At a total content of 20wt% of monomers, when the ratio of KA:DMAAm was 2:8, the water absorption rate was about 280g/g, and when the ratio of KA:DMAAm was 3:7, the water absorption rate was about 680g/g. appear. Compared to the test group in which the ratio of KA:DMAAm was 2:8 at the total monomer content of 20 wt% prepared in Example 2 above, the water absorption rate was about 240 g / g (FIG. 2), KA of Example 3: The high water absorption rate of the DMAAm ratio 2:8 test group could be seen as an increase in the water absorption rate due to the change in hot air drying conditions.

<Example 4>

Preparation of particulate hydrogels

The ratio of KA:DMAAm was set to 3:7, and the total content of the monomers combining KA and DMAAm was 20% by weight in the dispersion, and then divided into two test groups, one dried at about 80 ° C and the other at about 150 ° C. A particulate hydrogel was prepared in the same manner as in Example 1, except for drying with hot air.

<Test Example 4>

Moisture absorption rate measurement according to temperature change

Water absorption was measured in the same manner as in Test Example 1 for the particulate hydrogel of each test group prepared in Example 4. The results are shown in FIG. 4 .

When dried at 80 ° C, the water absorption rate was about 590 g / g, and when dried at 150 ° C, the water absorption rate was about 680 g / g. Compared to the results of Test Example 3, there was a change in water absorption between 80 ° C and 120 ° C, but there was no significant change in water absorption between 120 ° C and 150 ° C. In addition, it was determined that no problem appeared in the hydrogel even when the drying temperature was raised to 150 ° C.

<Test Example 5>

Drying time measurement according to temperature change

The ratio of KA:DMAAm was 0.25:9.75, 2:8, and 3:7, respectively, and the total content of the monomers of KA and DMAAm was 20% by weight in the dispersion, and a total of three test groups were prepared, and each test group Divide it into two again, dry one at about 80 ° C and dry the other at about 110 ° C. The hydrogel was prepared in the same manner as in Example 1 by drying with hot air, but the experiment was conducted for one day while measuring the drying rate of the sample at a predetermined time in each drying temperature environment. The results are shown in Figs. 5a and 5b.

In the case of the graph of FIG. 5a dried at 80 ° C., the hydrogels having water absorption rates of 100 (g / g) and 200 (g / g) showed similar drying behavior and were dried within 5 hours. On the other hand, the hydrogel with a water absorption rate of 300 (g / g) has more moisture than the hydrogels with a water absorption rate of 100 (g / g) and 200 (g / g), so drying took longer than 8 hours. .

In the case of the graph of FIG. 5b dried at 110 ° C., the behavior was similar to that of the graph on the left, but it dried more quickly, and the water absorption rate of 100 (g / g) and 200 (g / g) was within 3 hours, and the water absorption rate of 300 (g / g) Drying occurred within 5 hours.

There was a difference in the drying time to remove moisture according to the change in the drying temperature, and drying was performed quickly at 110 ° C for about 2 hours. In addition, the water absorption rate of 100 (g / g), 200 (g / g) has a slight difference, but the water absorption rate of 300 (g / g) hydrogel has a water absorption rate of 100 (g / g), 200 (g / g) ), and retained a lot of water for a considerably longer time than in the case of

<Example 5>

Particulate type with a water absorption rate of 300 g/g hydrogel manufacturing

A particulate hydrogel exhibiting a water absorption of about 300 g/g was prepared in the same manner as in Example 1 by setting the ratio of KA:DMAAm to 3:7 and the total content of the monomers combining KA and DMAAm to 20% by weight in the dispersion. .

<Test Example 6>

according to temperature change swelling behavior measurement

Experiments were conducted under temperature conditions of 4 ° C, room temperature (RT, 25 ° C) and 40 ° C to examine the swelling behavior according to temperature for the particulate hydrogel having a water absorption rate of about 300 g / g prepared in Example 5. did In order to compare the swelling behavior at the temperature of RT, which is the temperature that generally causes swelling, the cold refrigeration temperature and the water temperature of 4 ℃ and 40 ℃, which are slightly higher than room temperature, were arbitrarily set. The experiment was conducted by measuring the weight. The results are shown in Figs. 6a and 6b.

In the case of the graph of FIG. 6a, it was expressed as a ratio to show the temporal behavior of swelling, and in the case of the graph of FIG. 6b, it was expressed as temperature and swelling weight to find out the amount of swelling due to temperature change.

In the graph of FIG. 6a, the swelling degree increased significantly at the initial temperature of 40 ° C, and similar behavior was observed at RT and 4 ° C. The reason for the large increase in swelling degree at the initial temperature of 40 ° C is thought to be that the movement between molecules is more active at 40 ° C than at other temperatures, so that the dried sample absorbs moisture quickly and rises significantly. After absorption, it was assumed that the molecular motion of water in the sample became active and the swelling degree increased slowly because the amount that could be absorbed was small.

In the case of the graph of FIG. 6B, the swelling value increased as the temperature increased. As shown in the graph of FIG. 6A, it can be expected that a greater amount of water is absorbed due to increased mobility of water molecules according to temperature.

<Test Example 7>

Confirmation of swelling behavior according to pH

The particulate hydrogel having a water absorption rate of about 300 g/g prepared in Example 5 was swollen in distilled water at various pHs to confirm the swelling behavior.

In order to determine how the land is affected by acid or base contamination, pH was set in the range of pH 5 to 9, excluding strong acids and strong bases, and water absorption rate of about 300 (g / g) was applied to each pH aqueous solution. The indicated hydrogels were immersed for one day to sufficiently swell, and then the weights of the swollen hydrogels were measured and compared. The experimental results are shown in FIG. 7 . Although there was a slight difference in swelling degree depending on the pH, almost similar swelling behavior was observed, and the swelling value was close to 300 (g/g). Therefore, it can be determined that the swelling behavior of the hydrogel is not significantly affected by pH.

< test example 8>

hardness measurement

The ratio of KA:DMAAm was 4:6, 5:5, and 6:4, respectively, and the total content of the monomers of KA and DMAAm was 20% by weight in the dispersion, except for preparing a total of three test groups. A hydrogel was prepared in the same manner as in Example 1. The three test spheres thus prepared had a total content of 20% by weight of the monomers prepared in Example 3, and the ratio of KA:DMAAm was 0.25:9.75, 2:8, and 3: Hardness test was conducted with three test spheres of 7: . The test was conducted under the following conditions and methods.

Equipment Used: Universal Testing Machine (UTM, SHIMADZU, Japan)

Load cell: 100N

Compression speed: 1 mm/min

Sample size: Cylinder shape with a diameter of 3 mm and a height of 2 mm

Fracture stress: (pressure when NC hydrogel breaks (N) / surface area of NC hydrogel (mm ² ))

Fracture strain: (Length when NC hydrogel breaks (mm)/Height of NC hydrogel (mm))

Elastic modulus: slope of graph corresponding to 5% of fracture strain

Results are shown in FIGS. 8 and 9 . 8 is a result of fracture strain, and FIG. 9 is an elastic modulus result.

The higher the ratio of KA, the higher the degree of swelling, but the fracture stress was found to be weak under conditions where the degree of swelling increased. On the other hand, the difference in the length reduced until fracture (fracture strain) was found to be insignificant. The initial elastic modulus also showed insignificant difference according to the ratio of the monomers.

< test example 9>

seedling cultivation experiment

A seedling cultivation experiment was conducted for lettuce with the particulate hydrogel having a water absorption rate of about 300 g/g prepared in Example 5. For lettuce, seeds of blue lettuce were supplied from a nursery and used in the experiment.

Moisture content of the soil was calculated using a moisture retention curve using Hyprop (UMS GmbH, Munich, Germany). Moisture in the soil is changed through various pathways such as artificial irrigation, evaporation, and transpiration of plants. Moisture in the soil moves with the gradient of the pulling force of the soil and the pulling force of the roots of the plant. By measuring the water tension of the soil, it is possible to determine whether this moisture is available for use by plants or not. can judge

The experiment was conducted in a glass greenhouse relatively free from natural rainfall and external environmental conditions. The particulate hydrogel was treated differently at concentrations of 0, 0.5%, 0.1%, and 0.2%, and the difference in growth was confirmed by varying the irrigation period to 1, 2, and 3 days, respectively. After 20 minutes of saturation during irrigation, the weight was measured after 20 minutes. The experiment was conducted from October 2, 2021 to October 26. The results of the soil weight change rate after irrigation for each hydrogel treatment concentration are shown in FIG. 10.

After 24 hours of treatment, the increased weight was measured when irrigation was performed in a dry state, and the results are shown in FIG. 11a. Control (0%), 0.1%, and 0.2% treatment showed similar values to 4.88, 5.42, and 6.64%, respectively, in the case of control and 0.1%, and the increase rate was the highest in the treatment of 0.2%, which had the highest hydrogel concentration. .

As a result of observing the change rate of soil weight according to the irrigation cycle (daily, 3 days, and 6 days) after sowing lettuce, similar values were found in all treatment groups in the case of daily irrigation (Fig. 11a). In the case of irrigation once every 3 days, as shown in FIG. 11b, in the degree of drying, the hydrogel-treated treatment group had a smaller change than the control group, and the change in soil weight when water was supplied was smaller than that of the control group.

When water was supplied in the irrigation treatment zone once every 6 days, when the soil is the driest, 30.9%, 13.8%, and 10.2% in the control group, 0.1 and 0.2%, respectively, and when water was supplied in the hydrogel treatment zone, once every 3 days It was found to be similar to the case of irrigation. The results are shown in Fig. 11c. In the case of the control group, the increase rate was about twice that of the case of irrigation once every 3 days. Therefore, when the hydrogel was treated, it could be seen that the range of change was small because soil moisture was maintained compared to the control.

(1) Daily watering

The results of measuring the root length of the above-ground and underground dry parts of lettuce according to the treatment concentration of the particulate hydrogel are shown in Table 2 and FIGS. 12 and 13 below.

hydrogel concentration Ground weight (g) Underground building (g) Root length (cm) cont 0.07 0.01 14.2 a 0.1% 0.07 0.008 10.2 b 0.2% 0.07 0.018 11.6 b Significance NS NS ***

(NS: non-significant, *, **, *** were tested for significance at significance levels of 0.05, 0.01, and 0.001. The post-hoc test was performed with Tukey's HSD (honestly significant difference) test ( P =0.05))

When water was supplied every day, there was no statistical difference between the dry weight of the above-ground part and the dry weight of the underground part. 14 is a photograph of lettuce harvested during daily watering for each hydrogel treatment concentration.

(2) Irrigation once every 3 days

The results of measuring the root length of the above-ground and underground dry parts of lettuce according to the treatment concentration of the particulate hydrogel are shown in Table 3 and FIGS. 15 and 16 below.

hydrogel concentration Ground weight (g) Underground building (g) Root length (cm) cont 0.08 0.01 8.8 0.1% 0.07 0.01 9.0 0.2% 0.06 0.01 8.5 Significance NS NS NS

(NS: non-significant, *, **, *** were tested for significance at significance levels of 0.05, 0.01, and 0.001. The post-hoc test was performed with Tukey's HSD (honestly significant difference) test ( P =0.05))

When water was supplied once every 3 days, there was no statistical difference in all measurement items such as above-ground and underground dry weight and root length. 17 is a photograph of lettuce harvested when watering once every 3 days for each hydrogel treatment concentration.

(3) Irrigation once every 6 days

The results of measuring the root length of the above-ground and underground dry parts of lettuce according to the treatment concentration of the particulate hydrogel are shown in Table 4 and FIGS. 18 and 19 below.

hydrogel concentration Ground weight (g) Underground building (g) Root length (cm) cont 1.2 b 0.1 a 10.2 0.1% 1.4 a 0.1 a 10.3 0.2% 1.1 c 0.03 b 8.2 Significance *** *** NS

(NS: non-significant, *, **, *** were tested for significance at significance levels of 0.05, 0.01, and 0.001. The post-hoc test was performed with Tukey's HSD (honestly significant difference) test ( P =0.05))

When water was supplied once every 6 days, 0.1%, 0%, and 0.2% treatment appeared in the order of dry matter in the above-ground part, and 0.2% concentration showed a low value in the underground part. There was no statistical difference in root length. 20 is a photograph of lettuce harvested when watering once every 6 days for each hydrogel treatment concentration.

Since the multifunctional hydrogel of the present invention and the soil improver containing the same can selectively have a desired water absorption rate in the range of 90 to 300 times or more, different moisture environments vary depending on the growth stage and type of the plant and the cultivation environment. It can be used for all of the various uses that require it.

In particular, hydrogels and soil conditioners with a high water absorption rate of 300 times or more can be used for various purposes that require long-term moisture retention in the soil, including uses such as preventing desertification, rebuilding desolate lands, and minimizing plant damage due to abnormal climate. , it can be suitably used for raising seedlings in the growth stage of plants.

Hydrogels and soil improvers having a water absorption rate of 160 times or more and less than 300 times can be used universally for the same purposes as existing commercially available soil improvers, and can be particularly suitable for differentiation as a plant growth stage.

Hydrogels and soil improvers having a water absorption rate of 90 to less than 160 times can be suitably used, especially for soil cultivation, as a plant growth stage.

The hydrogel and soil improver of the present invention can be widely used for convenient maintenance, reducing manpower requirements, and reducing production and management costs in agriculture and forestry fields such as plant production and forest management.

The multifunctional hydrogel of the present invention described above, the soil improving agent containing the same, and the manufacturing method thereof are exemplary, and those skilled in the art to which the present invention belongs can make various modifications and other equivalent examples. You will know very well that it is possible. Therefore, it will be well understood that the present invention is not limited to the forms mentioned in the above description. It is understood that the true technical protection scope of the present invention should be determined by the technical spirit of the claims, and includes the spirit of the present invention defined by the claims of the present invention and all modifications, equivalents, and substitutes within its scope. It should be. In addition, terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately defines the concept of terms in order to explain his/her invention in the best way. Based on the principle that it can be done, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Claims (12)

An acrylate monomer and dimethylacrylamide (DMAAm) were added in a weight ratio of 0.2:9.8 to 3.5:6.5 to a 2-4% by weight laponite dispersion in which laponite was dispersed in water, and an initiator was added. adding and cross-linking to obtain a cross-linked hydrogel;
The cross-linked hydrogel is first dried at 90 to 150 ° C. to remove moisture, dipped in distilled water to remove unreacted monomers, and then dried again at 90 to 150 ° C. Preparing a hydrogel for a soil improver by a method comprising the step of obtaining,
In order to alternatively obtain a particulate hydrogel having a desired water absorption rate of 300 times or more and 90 to 160 times the water absorption rate by weight, by selecting any one of the following conditions (i), (ii), and (iii) A method for producing a multifunctional hydrogel for a soil improver, characterized in that obtaining a particulate hydrogel.
(i) The ratio of the acrylate monomer and dimethylacrylamide is set to a weight ratio of 2.5:7.5 to 3.5:6.5, and the content of the monomer in which the acrylate monomer and dimethylacrylamide are combined is 15% by weight or more 25% by weight in the dispersion. %, and the crosslinked hydrogel is firstly dried with hot air at 100 to 150 ° C for 2 to 48 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 100 to 150 ° C for 2 to 48 hours. and pulverized to obtain a particulate hydrogel with a water absorption rate of more than 300 times
(ii) The ratio of the acrylate monomer and dimethylacrylamide is set to a weight ratio of 1.5:8.5 to less than 2.5:7.5, and the content of the monomers obtained by combining the acrylate monomer and dimethylacrylamide is 25 to 35% by weight in the dispersion. And, the crosslinked hydrogel is firstly dried with hot air at 100 to 150 ° C for 2 to 48 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 100 to 150 ° C for 2 to 48 hours and pulverized. Thus, a particulate hydrogel with a water absorption rate of 300 times or more was obtained
(iii) The ratio of the acrylate monomer and dimethylacrylamide is set to a weight ratio of 0.2:9.8 to less than 0.5:9.5, and the content of the monomers obtained by combining the acrylate monomer and dimethylacrylamide is 15 to 35% by weight in the dispersion. And, the crosslinked hydrogel is first dried with hot air at 90 to 120 ° C for 1 to 36 hours, immersed in distilled water to remove unreacted monomers, and then dried with second hot air at 90 to 120 ° C for 1 to 36 hours and pulverized. Thus, a particulate hydrogel with a water absorption rate of 90 to 160 times was obtained
delete The method of claim 1,
In the step of obtaining the crosslinked hydrogel, N, N, N', N'-tetramethylenediamine is further added as a catalyst together with the initiator and crosslinked at 30 to 50 ° C. for 12 to 36 hours, soil Manufacturing method of multifunctional hydrogel for improving agent.
The method of claim 1,
In order to further adjust the water absorption rate within each range and conditions of 300 times or more, or 90 to 160 times the water absorption rate, including carrying out any one or more of (a), (b), and (c) below To, a method for producing a multifunctional hydrogel for a soil improver.
(a) Increasing the water absorption rate by increasing the content of the monomer in which the acrylate monomer and dimethylacrylamide are combined in the dispersion
(b) increasing the water absorption rate by increasing the content of the acrylate monomer in the ratio of the acrylate monomer and dimethylacrylamide
(c) The first and second hot air drying reduces the moisture absorption rate by lowering the temperature in the range of 90 to 120 ° C.
The method of claim 1,
In order to adjust the hardness together within the range and conditions of 300 times or more of the water absorption rate, or 90 to 160 times, performing any one or more of (a), (b), (d) below, Manufacturing method of multi-functional hydrogel for soil conditioner.
(a) increasing the content of a monomer combining the acrylate monomer and dimethylacrylamide in the dispersion
(b) increasing the content of the acrylate monomer in the ratio of the acrylate monomer and dimethylacrylamide
(d) increasing the content of laponite in the dispersion
delete delete A soil improver comprising a particulate hydrogel having a water absorption rate of 300 times or more and 90 to 160 times by weight, obtained by the manufacturing method of claim 1.
delete The soil improver according to claim 8, wherein the particulate hydrogel has a water absorption rate of 300 times or more and is used for raising seedlings.
delete The soil improver according to claim 8, wherein the particulate hydrogel has a water absorption rate of 90 to 160 times and is used for soil cultivation.

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