KR102293184B1 - Composition for absorbent composite, absorbent composite prepared using the same and method for preparing the same - Google Patents

Abstract

The present invention relates to an absorbent composite composition, an absorbent composite prepared using the same, and a method for preparing the same, and more particularly, to an absorbent composite composition comprising an acrylic acid-based polymer, alginate, and a wood-based biomass powder; an absorbent composite in which the absorbent composite composition is crosslinked; and preparing an absorbent composite composition, a primary cross-linking step of preparing a primary cross-linked composite by irradiating the absorbent composite composition with radiation, and a secondary cross-linked composite by immersing the primary cross-linked composite in a solution containing calcium ions It relates to a method for producing an absorbent composite comprising a secondary cross-linking step for producing a.

Description

Absorbent composite composition, absorbent composite prepared using the same, and method for manufacturing the same

The present invention relates to an absorbent composite composition, an absorbent composite prepared using the same, and a method for manufacturing the same, and more particularly, to an absorbent composite composition capable of producing an absorbent composite having high absorbency and excellent strength, and an absorbent composite manufactured using the same and to a method for manufacturing the same.

Hydrogels are widely known as absorbent materials, and such hydrogels or polymer hydrogels refer to three-dimensional network structures in which hydrophilic polymers are crosslinked by covalent or non-covalent bonds. Due to the hydrophilicity of the constituent materials, it swells by absorbing a large amount of water in aqueous solution and in an aqueous environment.

With these characteristics, in the early days, starting with application to hygiene products based mainly on absorbency, now, by introducing various additional functions, from pharmaceutical applications such as pharmaceuticals, food, cosmetics, civil engineering, agriculture, and sporting goods to industrial applications. It has been usefully used in a very wide range of fields. Research on such absorbent materials has been focused on improving rapid swelling and mechanical properties. However, there is still a problem in that it is difficult to improve the mechanical properties in the swollen state.

Accordingly, US Patent Application Publication No. 2005-0287191 discloses a method for producing a hydrogel and a fiber composite to attempt to improve the physical properties of the water-swelled state, but there is still a problem that the strength in the water-swelled state is insufficient.

Therefore, the demand for an absorbent material having excellent strength in the swollen state continues, and when an absorbent material that is biodegradable using radiation technology and has excellent mechanical properties is developed, the existing physicochemical properties such as weak properties and non-degradability are developed. It is expected that it will be able to overcome the limitations on the characteristics and satisfy various demands from related applied research.

Accordingly, one aspect of the present invention is to provide a composition capable of preparing an absorbent composite having excellent strength in a water-swelled state.

Another aspect of the present invention is to provide an absorbent composite having excellent strength in a water-swelled state prepared using the composition.

Another aspect of the present invention is to provide a method for preparing an absorbent composite having excellent strength in a water-swelled state.

According to one aspect of the present invention, there is provided an absorbent composite composition comprising an acrylic acid-based polymer, alginate, and lignocellulosic biomass powder.

According to another aspect of the present invention, there is provided an absorbent composite in which the absorbent composite composition of the present invention is crosslinked.

According to another aspect of the present invention, providing the absorbent composite composition; a primary crosslinking step of preparing a primary crosslinked composite by irradiating the absorbent composite composition with radiation; and a secondary cross-linking step of preparing a secondary cross-linked composite by immersing the primary cross-linked composite in a solution containing calcium ions is provided.

According to the present invention, there is provided an absorbent composite material having a high degree of water swelling and high absorbency and rapid swelling within a few minutes using radiation, and exhibiting excellent physical properties even in a water-swelled state, and a method for manufacturing the same.

1 shows the compressive strength of the absorbent composites prepared in Comparative Examples 1 to 3 and Example 1.
2 shows the compressive strength of the absorbent composites prepared in Comparative Examples 4 to 6 and Examples 2 to 4;
3 shows the swelling degree of the absorbent composites prepared in Examples 2 to 4.
4 is an SEM photograph showing the difference in surface properties according to the freeze-drying temperature.
5 is a photograph showing the test results for confirming the possibility of a soil substitute.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

According to the present invention, a composition capable of producing an absorbent composite having excellent strength in a water-swelled state is provided.

More specifically, the absorbent composite composition of the present invention is to include an acrylic acid-based polymer, alginate (Alginate) and lignocellulosic biomass powder.

According to the present invention, the acrylic acid-based polymer may be at least one polymer selected from the group consisting of polyacrylic acid, polymethacrylic acid, a monovalent metal salt of at least one of these acids, a divalent metal salt, an ammonium salt, and an organic amine salt. The acrylic acid-based polymer is preferably polyacrylic acid.

The lignocellulosic biomass powder of the present invention may be at least one selected from the group consisting of wood flour, coffee meal powder, rice husk, bamboo, bamboo, rice bran, kenaf and activated carbon. Preferably, the lignocellulosic biomass powder preferably contains activated carbon, for example, may be a mixture of activated carbon and wood flour, and in this case, excellent strength can be obtained during swelling. Since the lignocellulosic biomass powder has high hydrophilicity, porosity, and biodegradability, there is an advantage in that the moisture content of the composite material is increased.

The absorbent composite composition of the present invention may include, based on the total weight of the composition, 1 wt% to 20 wt% of an acrylic acid-based polymer; 0.1% to 10% by weight of alginate; 10% to 90% by weight of lignocellulosic biomass powder; and the remainder of distilled water (water). More preferably, the absorbent composite composition comprises 1 wt% to 10 wt% of an acrylic acid-based polymer, based on the total weight of the composition; 0.1% to 5% by weight of alginate; 10% to 50% by weight or 10% to 40% by weight of lignocellulosic biomass powder; and the remainder of the solvent.

The acrylic acid-based polymer is a component inducing gelation, and when the content of the acrylic acid-based polymer is less than 1% by weight, physical properties due to low gelation rate when irradiated with radiation are low, and there is a problem of shrinkage during drying, 20% by weight If it exceeds, it is not biodegradable due to a high cross-linked structure according to a high gelation rate, and there is a problem that the composite material is easily broken.

Meanwhile, the acrylic acid-based polymer of the present invention preferably has a weight average molecular weight of 450,000 to 1,250,000. When the weight average molecular weight of the acrylic acid-based polymer is less than 450,000, there is a problem that the composite is not sufficiently crosslinked, and when it exceeds 1,250,000, the viscosity increases and there is a problem of economic inefficiency.

The alginate is a component that allows secondary crosslinking to be performed with calcium ions in the secondary crosslinking step. When the content of alginate is less than 0.1% by weight, secondary crosslinking is insufficient, and when it exceeds 10% by weight, secondary crosslinking There is a problem in that the moisture content decreases due to the high gelation rate due to crosslinking, and shrinkage occurs during drying.

On the other hand, when a mixture of activated carbon and wood flour is used as the lignocellulosic biomass powder, the lignocellulosic biomass powder contains activated carbon in an amount of 10 to 90% by weight based on the total weight of the lignocellulosic biomass powder. Preferably, it may include, for example, 30 to 70% by weight of activated carbon and 30 to 70% by weight of wood flour based on the total weight of the lignocellulosic biomass powder.

On the other hand, according to the present invention, there is provided an absorbent composite prepared by using the absorbent composite composition described above. The absorbent composite of the present invention is a cross-linked absorbent composite composition of the present invention.

The crosslinking may be performed by irradiation with radiation, immersion in a solution containing calcium ions, or a combination thereof, preferably by immersion in a solution containing calcium ions following irradiation with radiation.

According to the present invention, the radiation is selected from the group consisting of gamma rays, x-rays, electron beams and ultraviolet rays, and it is preferable to use gamma rays.

The absorbent composite provided by the present invention can be used as a soil additive or a soil substitute because it has excellent swellability and absorbency and at the same time has excellent strength when swelling.

In more detail, for example, a large amount of leachate is generated due to decay of buried livestock during burial of livestock, and as these are discharged into the surface and groundwater, the surrounding environment is seriously polluted. By mixing and using as a soil additive, environmental leakage can be suppressed by adsorption of leachate.

In addition, since the composite material of the present invention can contain moisture for a long time due to its high absorbency, it can be used as a soil substitute for plant cultivation. In particular, it can be used for plant cultivation by replacing the soil in an area lacking moisture or being placed in a pot.

In addition, according to the present invention, there is provided a method for producing such an absorbent composite, the method for producing the same, in more detail, the steps of preparing the absorbent composite composition of the present invention; a primary crosslinking step of preparing a primary crosslinked composite by irradiating the absorbent composite composition with radiation; and immersing the primary cross-linked composite in a solution containing calcium ions to prepare a secondary cross-linked composite.

In general, the crosslinking reaction by radiation is a secondary free radical H or OH radical generated by radiolysis of water molecules as a crosslinking reaction of an acrylic acid-based polymer hydrogel when irradiated with radiation is a molecular chain of an acrylic acid-based polymer A radical is formed on the surface, resulting in cross-linked gelation of a three-dimensional network structure containing water. However, at a radiation dose with low ionization energy, since radicals are difficult to form in the molecular chain of the acrylic acid-based polymer, the crosslinking reaction of the acrylic acid-based polymer is low. There is a problem in the molding process because it has a property of being easily brittle even at low external pressure.

Therefore, the radiation dose is preferably 3kGy to 60kGy, more preferably 5 to 50kGy, for example, 10 to 400kGy. When the radiation dose is less than 3 kGy, there is a problem of insufficient gelation, and when the radiation dose exceeds 60 kGy, the degree of swelling tends to decrease.

In addition, the irradiation may be performed at a dose per hour of 5 kGy/h to 15 kGy/h. If the radiation dose per hour is less than 5 kGy/h, there may be a problem that the process execution time becomes longer, and if it exceeds 15 kGy/h, there may be a problem of decomposition of alginate.

According to the present invention, the solution containing calcium ions is a solution containing at least one calcium precursor selected from the group consisting of calcium chloride, calcium carbonate, calcium sulfate and calcium hydroxide, but is not limited thereto as long as it can release calcium ions. . The calcium solution is more preferably a calcium chloride solution.

The solvent of the solution containing the calcium ions may be water, for example, distilled water.

In this case, the concentration of calcium ions in the solution containing the calcium ions is preferably 0.1 to 10% by weight. When the concentration of calcium ions is less than 0.1% by weight, there is a problem that secondary crosslinking does not occur sufficiently, and when the concentration of calcium ions exceeds 10% by weight, the amount of calcium participating in secondary crosslinking is limited, so the process efficiency is lowered there is a problem.

According to the present invention, in order to provide a secondary cross-linked composite, the step of preparing the secondary cross-linked composite is performed by immersing the first cross-linked composite in a solution containing calcium ions for 30 to 90 minutes. When immersed for less than 30 minutes, calcium ions and alginate are not sufficiently combined, so secondary crosslinking is not sufficiently achieved.

Furthermore, when the absorbent composite of the present invention is prepared, it may further include the step of drying the secondary cross-linked composite, in which case the drying method may be performed, for example, by hot air drying, freeze drying, and the like.

Preferably, the drying is freeze-drying performed at a temperature of -10 to -30°C, and when freeze-drying is performed at such a temperature, the size of the pores increases.

The composite material dried as described above may be further used by pulverizing it.

As described above, according to the present invention, it is possible to provide an absorbent composite containing ultra-porous biomass by using radiation technology, and this technology is further improved through the use of biomass from recycled waste resources such as lignocellulosic coffee grounds, activated carbon, and sawdust. It is possible to dramatically improve the rate of swelling behavior, and thus, it is possible to dramatically increase the applicability and functionality to non-medical fields such as agriculture and industry as well as the existing medical fields.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to help the understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

1. Preparation of absorbent composites

Example One

200 g of polyacrylic acid (weight average molecular weight: 1,250,000), a water-soluble polymer, was dissolved in 1000 mL of tertiary distilled water at room temperature for 1 to 3 days. In addition, 5 g of alginate was dissolved in 1000 mL of tertiary distilled water at room temperature for 1 to 3 days. Then, the two aqueous solutions were mixed in a 50:50 ratio. Then, the mixed solution of 100ml polyacrylic acid and alginate was further mixed with wood flour obtained from waste wood at a content of 15% by weight, and stirred with a homogenizer (Primix coporation, coporation, T.K. Homomixer MarkII) until bubbles disappeared. As a result, an absorbent composite composition was prepared.

Thereafter, the composition was irradiated with gamma rays (Cobalt 60, MDS Nordion, Ottawa, Canada) at a dose of 10 kGy/h per hour at a total dose of 40 kGy to prepare a primary cross-linked complex. The first cross-linked complex obtained above _{was immersed in 100 mL of an aqueous calcium chloride solution containing calcium chloride (CaCl 2} ) in an amount of 1 wt % for 60 minutes to prepare a secondary cross-linked complex.

Thereafter, the absorbent composite was prepared by washing with distilled water several times to remove unreacted components, and then drying at 50° C. for 6 hours by hot air-dried.

Example 2 to 4

20% by weight of polyacrylic acid (weight average molecular weight: 1,250,000) and 0.5% by weight of alginate were used in a volume ratio of polyacrylic acid: alginate (70: 30) (Example 2), polyacrylic acid: alginate (50: 50) in a volume ratio (Example) 3), polyacrylic acid: alginate (30: 70) was used in a volume ratio (Example 4), and an absorbent composite was prepared by the same process as in Example 1, except that 10 wt% of activated carbon was used together with 10 wt% of wood flour. prepared.

comparative example One

An absorbent composite was prepared in the same manner as in Example 1, except that secondary crosslinking was not performed.

comparative example 2

An absorbent composite was prepared in the same manner as in Example 1, except that wood flour was not added.

comparative example 3

An absorbent composite was prepared in the same manner as in Example 1, except that wood flour was not added and secondary cross-linking was not performed.

comparative example 4 to 6

Absorbent composites were respectively prepared in the same manner as in Examples 2 to 4, except that secondary crosslinking was not performed, and these were referred to as 4 to 6 in comparison.

2. Measurement of Compressive Strength of Composites

The compressive strength of the absorbent composites obtained in Examples and Comparative Examples was measured.

As a result, as can be seen in FIG. 1 , it was confirmed that Comparative Examples 2 and 1, which were subjected to secondary crosslinking, showed higher compressive strength, and in particular, the compression of the composite obtained in Example 1 including wood flour It was confirmed that the strength was excellent.

Furthermore, referring to FIG. 2 , when wood flour and activated carbon are included together, it can be seen that the compressive strength of the composite material subjected to secondary crosslinking is significantly improved. Although not specified by the example number, the results obtained when the radiation dose was irradiated at 10 kGy and 20 kGy are also shown in (a) to (c) of FIG. 2 .

3. Measurement of swelling of composites

에서 증류수에 48시간 동안 침지시킨 후, 꺼내어 표면의 물기를 닦아준 후 길이를 측정하였다. The degree of swelling of each composite prepared according to Examples 2 to 4 was measured. To measure the degree of swelling, the dried composite (diameter about 6 mm, height about 2 mm) was

After immersing in distilled water for 48 hours, take it out and wipe the surface of the water, and then measure the length.

A graph comparing the results is shown in FIG. 3 . At this time, the degree of swelling _{was measured by measuring the weight of the swollen composite (W s} ) and the weight of the dried composite (W _d ), and then substituted into Equation (3) to express the degree of swelling as a percentage.

Swelling degree (%) = (W _S - W _d )/W _d X 100 ...................... Equation (3)

As a result, as shown in FIG. 3, it was confirmed that the composite materials of Examples 2 to 4 exhibited excellent swelling degree. Furthermore, it can be confirmed that the composite material of the present invention finally obtained after being immersed in a calcium solution does not change in shape when wet and can maintain its shape. Although not specified with the example number, FIG. 3 also shows the results when the radiation dose was irradiated with 10 kGy and 20 kGy.

4. Confirmation of composite surface structure according to freeze-drying temperature

A composite material was prepared by the same process as the composite material obtained by Comparative Example 2, except that the drying method was performed by freeze drying. At this time, the temperature of freeze-drying was changed to -20°C and -80°C, and the surface structure was confirmed by SEM.

As a result, as can be seen in FIG. 4 , it was confirmed that the pore size in the composite material was large when the freeze-drying temperature was high.

5. Identify potential soil substitutes

10 g of the composite material of the present invention obtained in Examples 2 to 4 was mixed with 500 g of soil, respectively, planted in pots (1L volume), and 100 ml for a total of 5 weeks in a room where the average temperature is maintained at 30 degrees. As a result of observing the growth for 4 weeks after watering, it was confirmed that the leaves of perilla drooped and the growth rate was slower than that of the samples of Examples 2 to 4 in the control group (Control-2) grown in a pot that was not mixed with the composite material. It was confirmed that as the acrylate content of the polyacrylate:alginate mixture increased, the growth was accelerated. The reason is that the soil containing the polyacrylate:alginate composite continuously contains moisture, so it is considered that the moisture required for plant growth is continuously supplied.

The results are shown in FIG. 5, and from the left, the control (Control-2), the composite mixed pot of Example 2, the composite mixed pot of Example 3, and the composite mixed pot of Example 4 are shown.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible within the scope without departing from the technical spirit of the present invention described in the claims. It will be apparent to those of ordinary skill in the art.

Claims (15)

An absorbent composite composition comprising an acrylic acid-based polymer, alginate, and wood-based biomass powder, cross-linked by primary cross-linking by gamma irradiation and secondary cross-linking by immersion in a solution containing calcium ions .
According to claim 1, wherein the acrylic acid-based polymer is polyacrylic acid, polymethacrylic acid, at least one polymer selected from the group consisting of a monovalent metal salt, a divalent metal salt, an ammonium salt, and an organic amine salt of at least one of these acids, Absorbent composite.
The absorbent composite of claim 1, wherein the lignocellulosic biomass powder is at least one selected from the group consisting of wood flour, coffee meal powder, rice husk, sawdust, bamboo, rice straw, kenaf and activated carbon.
According to claim 1, wherein the absorbent composite composition is based on the total weight of the composition, based on the total weight of the composition, acrylic acid-based polymer 1% to 20% by weight, alginate 0.1% to 10% by weight, lignocellulosic biomass powder 10% to 90% by weight %, and the balance solvent.
The absorbent composite of claim 4, wherein the lignocellulosic biomass powder contains activated carbon in an amount of 10 to 90% by weight based on the total weight of the lignocellulosic biomass powder.
delete delete The absorbent composite of claim 1, wherein the absorbent composite is used as a soil additive or a soil substitute.
Preparing an absorbent composite composition comprising an acrylic acid-based polymer, alginate, and wood-based biomass powder;
a first crosslinking step of preparing a first crosslinked composite by irradiating the absorbent composite composition with gamma rays; and
A method for producing an absorbent composite, comprising a secondary crosslinking step of preparing a secondary crosslinked composite by immersing the primary crosslinked composite in a solution containing calcium ions.
delete The method of claim 9, wherein the gamma irradiation is performed at a dose of 3 kGy to 60 kGy.
The method of claim 9, wherein the solution containing calcium ions is a solution containing at least one calcium precursor selected from the group consisting of calcium chloride, calcium carbonate, calcium sulfate and calcium hydroxide.
The method of claim 9, wherein the concentration of calcium ions in the solution containing the calcium ions is 0.1 to 10% by weight.
10. The method of claim 9, further comprising drying the secondary cross-linked composite.
The method of claim 14, wherein the drying is freeze-drying performed at a temperature of -10 to -30°C.

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