KR102597758B1 - Manufacturing method for superabsorbent material using cellulose derivative - Google Patents

Abstract

The present invention uses a mixture of two types of cellulose derivatives with different viscosity, and is a method of manufacturing a superabsorbent material using a cellulose derivative that can have higher absorbency than existing absorbent materials using cellulose derivatives and commercial superabsorbent resins. It's about. The present invention includes the steps of (a) mixing two or more types of cellulose derivatives with different viscosities to prepare a cellulose derivative mixture solution; (b) mixing a cross-linking agent with the cellulose derivative mixture solution to form a porous polymer network; (c) preparing an absorbent material raw material by mixing a polymer additive with the cellulose derivative mixture solution in which the porous polymer network is formed; and (d) molding the absorbent material raw material. A method for manufacturing a highly absorbent material using a cellulose derivative is provided.

Description

{Manufacturing method for superabsorbent material using cellulose derivative}

The present invention relates to a method of manufacturing a superabsorbent material using a cellulose derivative. More specifically, it involves using a mixture of two types of cellulose derivatives with different viscosity, which can be used in combination with existing absorbent materials and superabsorbent resins using cellulose derivatives. It relates to a method of manufacturing a highly absorbent material using a cellulose derivative that can have higher absorbency than that of the present invention.

Absorbent products for personal care, such as baby diapers, adult pads, or feminine hygiene products, include an absorbent core comprising superabsorbent resin particles dispersed in a fibrous matrix. These superabsorbent resins are generally water-swellable, water-insoluble absorbents that have a high absorption capacity for body fluids.

Superabsorbent polymers (SAP) commonly used for these purposes are mostly derived from acrylic acid derived from fossil fuels such as petroleum and are known to be non-renewable. That is, it is known that general acrylic acid polymers and superabsorbent resins do not exhibit biodegradability.

More specifically, the absorbent resin is at least partially neutralized polyacrylic acid, hydrolyzed starch/acrylonitrile graft copolymer, neutralized starch/acrylic acid graft copolymer, neutralized vinyl acetate/acrylic acid ester copolymer, or hydrolyzed These include acrylamide copolymers, etc., which do not exhibit biodegradability.

However, as interest in environmental issues has increased significantly recently, interest in absorbable polymers with biodegradability is increasing. Examples of previously known biodegradable and absorbent polymers include natural polymers, mixtures of synthetic polymers thereof, or graft polymers of natural polymers and synthetic polymers, and research on these is actively underway.

For example, among the polymers known so far, an example of a relatively commercially successful biodegradable polymer is sodium carboxymethylcellulose obtained by modifying natural cellulose. Since these polymers are obtained using cellulose, which has a relatively low cost, as a starting material, the polymers obtained therefrom have several advantages.

An example of producing a highly absorbent polymer from cellulose is a method of obtaining a product with high biodegradability by reacting cellulose with a crosslinking agent having an ionic functional group. However, this method is not economical because its manufacturing cost is very high. As another example, there is a method of modifying cellulose to have a carboxyl group and then crosslinking the modified cellulose with a crosslinking agent. However, this method also has the disadvantage that the biodegradability of the product is not sufficient and only limited types of materials can be obtained.

Moreover, when biodegradable absorbable polymers are obtained using natural polymers using previously known methods, there is a disadvantage that it is difficult to apply them commercially. For example, previously biodegradable polymers derived from cellulose have poor physical properties such as water absorption compared to non-biodegradable absorbent resins derived from fossil fuels, and their manufacturing costs are high. In addition, even when polyacrylate is grafted onto a natural polymer, there are disadvantages such as difficulty in controlling the degree of decomposition of the polymer, poor absorbency and physiological properties, and relatively high raw material costs.

Therefore, there is a need for a new cellulose-based polymer absorbent material and its manufacturing method with a biomass content of 90-99% by weight that solves these shortcomings of cellulose-based polymers and has superior absorbency compared to existing superabsorbent polymers.

(0001) Republic of Korea Patent Publication No. 10-2000-0069445 (0002) Republic of Korea Patent Publication No. 10-2022-0167415

In order to solve the above-described problem, the present invention uses a mixture of two types of cellulose derivatives with different viscosity, and provides a cellulose derivative that can have higher absorbency than existing absorbent materials using cellulose derivatives and commercial superabsorbent resins. The aim is to provide a method for manufacturing a highly absorbent material using .

In order to solve the above-described problem, the present invention includes the steps of (a) mixing two or more types of cellulose derivatives with different viscosities to prepare a cellulose derivative mixture solution; (b) mixing a cross-linking agent with the cellulose derivative mixture solution to form a porous polymer network; (c) preparing an absorbent material raw material by mixing a polymer additive with the cellulose derivative mixture solution in which the porous polymer network is formed; and (d) molding the absorbent material raw material. A method for manufacturing a highly absorbent material using a cellulose derivative is provided.

In one embodiment, the cellulose derivative may be carboxymethylcellulose or a compound containing carboxymethylcellulose.

In one embodiment, the cellulose derivative mixture includes 5 to 20% by weight of first carboxymethylcellulose with a degree of substitution of 0.4 or more and a viscosity of 10,000 to 100,000 cps, and a second carboxymethylcellulose with a degree of substitution of 0.4 or more and a viscosity of 10 to 300 cps. It may be a mixture of 80 to 95% by weight of carboxymethyl cellulose.

In one embodiment, the second carboxymethyl cellulose may be derived from wood.

In one embodiment, the cellulose derivative mixture solution may be a mixture of 0.1 to 5 parts by weight of the cellulose derivative mixture relative to 100 parts by weight of the solvent.

In one embodiment, the solvent may include one or more selected from the group of water, ethanol, ethanol, and IPA.

In one embodiment, the cross-linking agent may be an anionic cross-linking agent, and the polymer additive may be an anionic or cationic additive.

In one embodiment, the anionic crosslinking agent may include one or more selected from the group consisting of citric acid, maleic acid, epichlorohydrin, and aluminum sulfate. there is.

In one embodiment, the cationic additive is starch, gum, chitin, chitosan, glycan, galactan, pectin, mannan, dextrin, acrylic acid, methacrylic acid, polyvinyl alcohol, polyamine, polyethyleneimine, polyethylene oxide, poly It may include one or more selected from the group consisting of propylene oxide, polyurethane, and polyamidoamine epichlorohydrin.

In one embodiment, the anionic crosslinking agent may be mixed in an amount of 10 to 50 parts by weight based on 100 parts by weight of the solvent contained in the cellulose derivative mixture solution.

In one embodiment, the polymer additive may be mixed in an amount of 0.001 to 0.01 parts by weight based on 100 parts by weight of the solvent contained in the cellulose derivative mixture solution.

In one embodiment, the step (d) of molding the absorbent material raw material includes: (i) molding the absorbent material raw material into a certain shape using a filtration method, a coating method, or a spraying method; and (ii) separating the solvent in the molded absorbent material raw material and drying the solid content to form a film.

In one embodiment, the step (d) of molding the absorbent material raw material includes: (1) mixing 0.1 to 1% by weight of a shell-forming additive in a solvent to prepare a core-shell forming solution; (2) adding the absorbent material raw material dropwise to the shell forming solution to form highly absorbent particles in the core-shell forming solution; and (3) separating the superabsorbent particles, followed by washing and drying.

The present invention also provides a highly absorbent material using the cellulose derivative prepared by the above method.

In one embodiment, the highly absorbent material may have a porosity of 50 to 85%.

In one embodiment, the highly absorbent material may additionally include 0.001 to 0.01% by weight of anionic polymer based on the total weight.

The present invention also provides a film-type highly absorbent material using the cellulose derivative prepared by the above method.

The present invention also provides a particle-type highly absorbent material using the cellulose derivative prepared by the above method.

The method of manufacturing a super-absorbent material using cellulose derivatives according to the present invention uses a combination of two types of cellulose derivatives with different viscosities, and produces a super-absorbent material with higher absorbency than existing absorbent materials and super-absorbent resins using cellulose derivatives. Materials can be manufactured.

In addition, the method for manufacturing a highly absorbent material using a cellulose derivative according to the present invention can use wood-derived cellulose derivatives, making it possible to manufacture a highly absorbent material at a lower price than chemically synthesized cellulose derivatives.

In addition, the method of manufacturing a super-absorbent material using a cellulose derivative according to the present invention manufactures a super-absorbent material in various shapes, making it possible to supply a super-absorbent material for each application.

Figure 1 shows a method of manufacturing a highly absorbent material according to an embodiment of the present invention.
Figure 2 shows a method of manufacturing a film-type highly absorbent material according to an embodiment of the present invention.
Figure 3 shows a method of manufacturing a particle-type highly absorbent material according to an embodiment of the present invention.
Figure 4 shows a high-absorbent material manufactured according to an embodiment of the present invention, (a) is a film-type high-absorbent material, (b) is a particle-type high-absorbent material, and (c) is a high-absorbent material absorbed. The subsequent size changes are shown respectively.
Figure 5 is an enlarged photograph of the surface of a film-type highly absorbent material according to an embodiment of the present invention.
Figure 6 is an observation of the surface of a film-type highly absorbent material according to an embodiment of the present invention.
Figure 7 is an enlarged photograph of the surface of a particle-type superabsorbent material according to an embodiment of the present invention.
Figure 8 shows the results of a urine absorption ability test according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. In describing the present invention, if it is determined that a detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted. Throughout the specification, singular expressions should be understood to include plural expressions, unless the context clearly indicates otherwise, and terms such as “comprise” or “have” refer to the features, numbers, steps, operations, or components being described. , it is intended to specify the existence of a part or a combination thereof, but should be understood as not excluding in advance the possibility of the existence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. . In addition, when performing a method or manufacturing method, each process forming the method may occur differently from the specified order unless a specific order is clearly stated in the context. That is, each process may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the opposite order.

The technology disclosed in this specification is not limited to the implementation examples described herein and may be embodied in other forms. However, the implementation examples introduced here are provided to ensure that the disclosed content is thorough and complete and that the technical idea of the present technology can be sufficiently conveyed to those skilled in the art. In order to clearly express the components of each device in the drawing, the sizes of the components, such as width and thickness, are shown somewhat enlarged. When describing the drawing as a whole, it is described from the observer's point of view, and when an element is mentioned as being located above another element, this means that the element may be located directly above another element or that additional elements may be interposed between those elements. Includes. Additionally, those skilled in the art will be able to implement the idea of the present invention in various other forms without departing from the technical idea of the present invention. In addition, the same symbols in a plurality of drawings refer to substantially the same elements.

As used herein, the term 'and/or' includes a combination of a plurality of listed items or any of a plurality of listed items. In this specification, 'A or B' may include 'A', 'B', or 'both A and B'.

The present invention includes the steps of (a) mixing two or more types of cellulose derivatives with different viscosities to prepare a cellulose derivative mixture solution; (b) mixing a cross-linking agent with the cellulose derivative mixture solution to form a porous polymer network; (c) preparing an absorbent material raw material by mixing a polymer additive with the cellulose derivative mixture solution in which the porous polymer network is formed; and (d) molding the absorbent material raw material. It relates to a method of manufacturing a highly absorbent material using a cellulose derivative.

In the case of absorbers using existing cellulose derivatives, chemically synthesized cellulose is used or highly purified cellulose is used by chemically treating cellulose derived from wood. Most of these celluloses are manufactured and used in the form of carboxymethylcellulose (CMC). In the case of carboxymethyl cellulose, it can have various viscosities depending on the degree of polymer polymerization, and it is generally known that the higher the degree of polymer polymerization, the higher the viscosity.

In particular, in the case of carboxymethyl cellulose (CMC), which is widely used as an absorbent, high molecular weight carboxymethyl cellulose is used to ensure workability. On the other hand, carboxymethyl cellulose obtained from wood has a low degree of polymerization and therefore low viscosity.

Figure 1 shows a method for manufacturing a highly absorbent material according to the present invention.

In the case of the present invention, wood-derived carboxymethylcellulose can be directly utilized by mixing two or more types of cellulose derivatives with different viscosities to prepare a cellulose derivative mixture solution.

The cellulose derivative may be carboxymethylcellulose or a compound containing carboxymethylcellulose. In the case of the above cellulose, it can be used as is, but in order to further increase the absorption rate, it is preferable to manufacture it in the form of carboxymethylcellulose or a compound containing it.

The cellulose derivative mixture may be a mixture of 5 to 20% by weight of first carboxymethyl cellulose with a viscosity of 1,000 to 100,000 cps and 80 to 95% by weight of second carboxymethyl cellulose with a viscosity of 10 to 300 cps.

The first carboxymethyl cellulose may be the same carboxymethyl cellulose used in existing absorbents. That is, in the case of the first carboxymethyl cellulose, carboxymethyl cellulose with a high degree of polymerization can be used, and in the case of this first carboxymethyl cellulose, it may be chemically synthesized or manufactured by appropriately processing wood-derived carboxymethyl cellulose.

Additionally, in general, the viscosity of carboxymethyl cellulose can be measured through the method of ASTM D 1439-03, and specifically, it can be prepared as a 1% aqueous solution and measured at 100 rpm at room temperature. The first carboxymethyl cellulose of the present invention may have a viscosity of 10,000 to 100,000 cps. If the viscosity of the first carboxymethyl cellulose is less than 10,000 cps, it may be difficult to form a polymer network in the step described later, and if it exceeds 100,000 cps, mixing may be difficult due to the high viscosity.

Additionally, the first and second carboxymethyl celluloses may have a degree of substitution of 0.4 or more. The degree of substitution refers to the average number of carboxymethyl groups substituted for one glucose constituting cellulose. If the degree of substitution is less than 0.4, it may be difficult to mix and process because it is not soluble in water. In addition, the degree of substitution may be 1 or less, preferably 0.8 or less. The higher the degree of substitution, the higher the solubility and improved physical properties, but there are limits to substitution. Therefore, it is preferable that the degree of substitution is 1 or less.

The second carboxymethylcellulose may be wood-derived carboxymethylcellulose. As seen above, in the case of carboxymethyl cellulose, which is conventionally used as an absorbent, carboxymethyl cellulose with a high degree of polymerization is used. Carboxymethyl cellulose with such a high degree of polymerization has the disadvantage of increasing the unit cost of the absorbent as it requires a large production cost.

On the other hand, wood-derived carboxymethyl cellulose has a low unit cost as it is produced and extracted directly from wood, but has a low degree of polymerization, which limits its use alone in the production of absorbent materials. However, in the case of the present invention, carboxymethyl cellulose with low viscosity is used by mixing carboxymethyl cellulose (primary carboxymethyl cellulose) with existing high viscosity, so the absorbent can be manufactured at low cost through a simple mixing method It can have an equal or greater effect than commercially available superabsorbent polymers.

At this time, the cellulose derivative mixture may be a mixture of 5 to 20% by weight of first carboxymethyl cellulose and 80 to 95% by weight of second carboxymethyl cellulose, and more preferably 10% by weight of first carboxymethyl cellulose and 20% by weight of second carboxymethyl cellulose. It may be a mixture of 90% by weight cellulose. An optimal absorbent can be manufactured within the above ratio, but when the primary carboxymethyl cellulose is used in less than 5% by weight, it is difficult to form a polymer network, and when used in excess of 20% by weight, the absorption performance deteriorates and the absorbent The manufacturing cost may increase.

The second carboxymethyl cellulose may have a viscosity of 10 to 300 cps, most preferably less than 50 cps. If the viscosity of the second carboxymethyl cellulose exceeds 300 cps, it may be difficult to form a porous polymer network and the absorption performance may decrease.

The cellulose derivative mixture solution may be a mixture of 0.1 to 5 parts by weight of the cellulose derivative mixture relative to 100 parts by weight of the solvent. The solvent used at this time may be used without limitation as long as it is capable of dissolving or dispersing the cellulose derivative mixture, and may preferably include one or more selected from the group of water, ethanol, ethanol, and IPA.

In addition, the cellulose derivative mixture solution is preferably used in a mixture of 0.1 to 5 parts by weight of the cellulose derivative mixture relative to 100 parts by weight of the solvent. If the cellulose derivative mixture is used in an amount of less than 0.1 parts by weight, manufacturing efficiency may be reduced due to the large amount of solvent, and if it is included in more than 5 parts by weight, it may be difficult to produce a uniform absorbent material or achieve absorbent performance during manufacturing. .

After the cellulose derivative mixture solution is prepared as described above, a crosslinking agent may be mixed with the cellulose derivative mixture solution to form a porous polymer network.

Through the primary crosslinking process of the cellulose derivative mixture and the crosslinking agent, core crosslinking is formed in the backbone of the cellulose derivative mixture, thereby obtaining a porous cellulose derivative with a three-dimensional network structure. Cellulose derivatives to which core crosslinking has been applied in this way ensure high dispersibility and absorption of moisture.

The core crosslinking agent may be an anionic crosslinking agent, and specifically, one or more selected from the group consisting of citric acid, maleic acid, epichlorohydrin, and aluminum sulfate. It can be included. Citric acid can be preferably used.

In the case of the anionic crosslinking agent, as it has a negative electric charge in an aqueous solution, it can suppress entanglement or bonding reactions between carboxymethyl cellulose molecules, and thereby induce the formation of a porous polymer network. Looking at this in detail, in the case of a general crosslinking agent, entanglement may occur between carboxymethylcellulose molecules while crosslinking carboxymethylcellulose, and each carboxymethylcellulose can be chemically bonded to form carboxymethylcellulose with a high degree of polymerization. . However, in the case of the anionic crosslinking agent used in the present invention, the reaction can proceed in the absence of electrostatic attraction for the bonding of carboxymethylcellulose, and thus excessive entanglement or bonding between carboxymethylcellulose molecules can be prevented.

The content of the cross-linking agent may be 10 to 50 parts by weight, preferably 10 to 30 parts by weight, and most preferably 20 parts by weight, based on 100 parts by weight of the solvent contained in the cellulose derivative mixture solution. When the content of the cross-linking agent is within the above range, the cross-linking reaction efficiency is excellent and the cross-linking density is appropriate, so it is possible to provide a cellulose derivative-based highly absorbent material with good gel strength and centrifuge retention capacity (CRC). there is. However, if the cross-linking agent is used in less than 10 parts by weight, the cross-linking reaction may be reduced and the absorption rate may decrease, and if it is used in more than 50 parts by weight, the absorption rate of the absorbent may be reduced due to excessive cross-linking reaction.

Step (b) may be performed at a temperature of 50 to 100°C, preferably 60 to 80°C, and most preferably 70°C. If the temperature is less than 50°C, a polymer network may not be formed by the crosslinking agent, and if the reaction is performed at a temperature exceeding 100°C, the solution may boil and the reaction efficiency may decrease.

Additionally, step (b) may be performed for 10 to 60 minutes, preferably 20 to 40 minutes, and most preferably 30 minutes. If the reaction in step (b) is performed for less than 10 minutes, it may be difficult to form a polymer network due to insufficient reaction time, and if it exceeds 60 minutes, it is inefficient because no further reaction is performed.

After the formation of the polymer network is completed as described above, (c) a polymer additive can be mixed with the cellulose derivative mixture solution in which the porous polymer network has been formed to produce an absorbent material raw material.

In the present invention, unlike the conventionally used method, such as filtering a cellulose slurry and then dehydrating and drying it using an organic solvent, a polymer network solution prepared using the cellulose is obtained and directly processed and molded. Since the product is being manufactured, dispersibility and absorbency can be further improved.

Looking at this in detail, the dispersibility is a measure for judging liquid permeability, and at the same time, it is a physical property closely related to the gel blocking phenomenon. Specifically, when an absorbent article is manufactured using cellulose derivative particles with poor dispersibility, when liquid is absorbed into the absorbent article, the cellulose derivative particles float to the upper layer of the absorbent article and are crowded together. In this case, they are located in the upper layer. Cellulose derivative particles quickly absorb water and gel, forming a gel film on the surface of the absorbent layer, causing a gel blocking problem. Afterwards, when the liquid is absorbed again into the absorbent article, it does not pass through the gel membrane, that is, the liquid permeability is lowered, so the cellulose derivative particles present inside the absorbent article cannot participate in the absorption of the liquid, and after the gel membrane is formed, Absorbency becomes close to zero.

However, according to the present invention, cellulose derivative particles with excellent dispersibility can be provided, so the above gel blocking problem can be solved, and an absorbent article with excellent long-term absorbency can be provided.

However, in the case of the porous polymer network, it may be difficult to mold into a product because it is simply a polymer network made of cellulose. Therefore, in the case of the present invention, the stability of the polymer network can be increased and the product can be easily formed by mixing the polymer additive with the polymer network.

In the case of the existing invention, the product is manufactured by mixing the cellulose in slurry form. In this case, due to the difficulty in slurry-type processing, most absorbents are manufactured in particle form. Additionally, they are manufactured by drying the slurry and then pulverizing it, resulting in a lot of variation between each particle. However, in the case of the present invention, since it can be manufactured in a state close to a solution, it is possible to produce a film-type absorbent in addition to a particle-type absorbent. Additionally, even when manufactured in particle form, physical differences between each particle can be minimized.

The polymer additive used at this time may be a cationic additive. As seen above, since the cross-linking agent has anionic properties, the cross-linking reaction can be performed while minimizing aggregation of the carboxymethyl cellulose. However, in the case of the polymer additive, as opposed to this crosslinking reaction, using a cationic additive can form an electrostatic bond with the polymer network, thereby maintaining a more stable structure.

The cationic additives specifically include starch, gum, chitin, chitosan, glycan, galactan, pectin, mannan, dextrin, acrylic acid, methacrylic acid, polyvinyl alcohol, polyamine, polyethyleneimine, polyethylene oxide, polypropylene oxide, poly It may contain one or more selected from the group consisting of urethane and polyamidoamine epichlorohydrin, preferably chitosan or polyamidoamine epichlorohydrin, more preferably polyamidoamine epichlorohydrin. .

The polymer additive may be mixed in an amount of 0.5 to 2.0 parts by weight based on 100 parts by weight of the solvent contained in the cellulose derivative mixture solution. If the polymer additive is added in less than 0.5 parts by weight, the processing process described later may not be possible, and if it is mixed in excess of 2.0 parts by weight, it may induce excessive bonding between cellulose derivative molecules and lower the absorption rate.

Step (c) may be performed at a temperature of 50 to 100°C, preferably 60 to 80°C, and most preferably 70°C. If the temperature is below 50℃, processing may be difficult because the viscosity of the solution is excessively increased by the polymer additive, and if the reaction is performed at a temperature exceeding 100℃, the solution may boil and bubbles may be incorporated into the product. there is.

Additionally, step (c) may be performed for 10 to 60 minutes, preferably 20 to 40 minutes, and most preferably 30 minutes. If the reaction in step (c) is performed for less than 10 minutes, mixing of the polymer additives may not be completed and agglomeration of the cellulose or polymer additives may occur, and if it exceeds 60 minutes, no further reaction is performed, making it inefficient. am.

After the absorbent material raw material is manufactured as described above, it can be molded to manufacture the highly absorbent material and its products. At this time, in the case of the present invention, the film-type product manufacturing method (see Figure 2) and the particle-type product manufacturing method (see Figure 3) can be selectively used.

The method of manufacturing the film-type product includes (i) forming the absorbent material into a certain shape through a filtration method, a coating method, or a spraying method; and (ii) separating the solvent in the molded absorbent material raw material and drying the solid content to form a film.

Looking at this in detail, the filtration method is a method of manufacturing a certain shape by injecting the absorbent material raw material into the upper part of the membrane and then creating a negative pressure at the lower part of the membrane to extract the solvent from the lower part of the membrane. At this time, in order to increase the durability of the filter, a mesh-type support may be additionally installed on the upper part of the membrane. In the case of the mesh-type support, the durability of the filter can be further increased by being located in the center of the filter.

The coating method is to install a device that can adjust the coating film to a certain thickness, such as a doctor blade or bar that is perpendicular to the moving floor surface and has a predetermined height from the floor surface, then supplies the absorbent material raw material to one side, and then This is a method of moving the floor to the other side. In this case, the absorbent material in the suspension settles to the bottom and is discharged through a gap between the doctor blade and the bottom surface, so that it can be arranged to have a constant height.

The spraying method is a method of uniformly spraying the absorbent material raw material using a spray, and is a method of manufacturing a filter by uniformly spraying the absorbent material raw material on a substrate.

As described above, the absorbent raw material is molded to have a certain shape, and then the solvent is removed and dried to produce a film-type product.

In addition to the above film-type products, particle-type products can also be manufactured.

To this end, (d) molding the absorbent material raw material includes (1) mixing 0.1 to 1% by weight of a shell-forming additive in a solvent to prepare a shell-forming solution; (2) adding the absorbent material raw materials dropwise to form highly absorbent particles in the core-shell forming solution; and (3) separating the superabsorbent particles, followed by washing and drying.

In the case of existing cellulose absorbent particles, they are manufactured by preparing a cellulose suspension or slurry, then drying and pulverizing it. However, in the case of the present invention, a kind of core-shell structure can be formed by dropwise adding the absorbent material raw materials to a shell forming solution containing a thickener, thereby further improving the stability of the absorbent material.

The core-shell forming solution may be prepared by mixing 0.1 to 1% by weight of a shell forming additive in a solvent. At this time, the additive for forming the shell may be starch, gum, chitin, chitosan, glycan, galactan, pectin, or mannan, and preferably chitosan. Additionally, in the case of the solvent, a solvent capable of dissolving the shell forming additive can be used, and is preferably water.

In addition, the additive for forming the shell may be mixed in an amount of 0.1 to 1% by weight in the solvent. If the shell-forming additive is mixed in an amount of less than 0.1% by weight, it may be difficult to form a core-shell structure, and if it is more than 1% by weight, the viscosity of the solution for core-shell production increases, making processing by dropwise addition of absorbent material raw materials impossible. You can.

After the core-shell forming solution is prepared as described above, the absorbent material raw materials can be added dropwise to the shell forming solution to form highly absorbent particles in the shell forming solution. At this time, the dropwise addition of the absorbent material raw material is preferably performed at a height of 10 to 30 cm based on the top of the solution. If the dropwise addition is performed at a height of less than 10 cm, the absorbent material raw material does not penetrate to a sufficient depth into the shell forming solution, and if the dropwise addition is performed at a height exceeding 30cm, the absorbent material raw material is absorbed into the shell due to impact. It may not be able to maintain its spherical shape when in contact with the forming solution.

As described above, through the dropwise addition of absorbent raw materials, the cellulose polymer network can form the core, and the thickener and polymer additives can form the shell. At this time, since the thickener may have similar physical properties and behavior to the polymer additive, a network structure can be formed on the surface of the droplet by dropwise addition, and a shell portion can be formed through this.

After the dropwise addition is completed as described above, superabsorbent particles may be formed inside the shell forming solution, which can be separated, washed, and dried to produce a particle-type superabsorbent material. In addition, it is preferable to use ethanol or methanol for washing at this time, and more preferably, ethanol can be used. In the case of ethanol or methanol, the evaporation rate is faster than that of water and leaves no residue, so it can be easily used for cleaning the manufactured highly absorbent material.

The present invention also relates to a highly absorbent material using the cellulose derivative prepared by the above method.

The present invention also provides a film-type highly absorbent material using the cellulose derivative prepared by the above method.

The present invention also provides a particle-type highly absorbent material using the cellulose derivative prepared by the above method.

As discussed above, the highly absorbent material may be manufactured in the form of a film or particle. When the highly absorbent material is manufactured in a film form, it can be used to attach to the human body to absorb unwanted exudates, and can also be used to prevent leaks in pipes, etc. At this time, the film-type highly moisture-soluble material expands nearly 40 times in volume when it absorbs water, so when used in a sealing area, its volume expands when it comes into contact with moisture, preventing leakage from occurring in the sealing area.

In addition, when the highly absorbent material is used in particle form, it can be used as a moisture absorbent.

The highly absorbent material may have a porosity of 50 to 85%. It is generally known that the higher the porosity, the higher the water absorption rate. The highly absorbent material of the present invention may have a porosity of 50 to 85% and, accordingly, may have an absorption rate of up to 800 g/g. The porosity can be measured using a mercury intrusion method or a nitrogen adsorption method.

In the case of the film-type material, the average pore diameter may be 100 to 200 μm, the porosity measured by the mercury intrusion method may be 50 to 60%, and the apparent density may be 0.5 to 0.8 g/ml. In addition, the particle-type material may have an average particle diameter of 0.5 to 1.5 mm, a specific surface area of 50 to 90 m2/g, and a porosity measured by the nitrogen adsorption method of 70 to 85%. Within the above range, the super absorbent material may have high absorbency, but if it is outside the above range, the absorbency may decrease or physical properties may be reduced.

The highly absorbent material may additionally contain 0.001 to 0.005% by weight of anionic polymer based on the total weight. The highly absorbent material of the present invention has high absorbency. However, in order to absorb liquids containing various components such as human blood or urine, it is preferable to use an anionic polymer mixed in an amount of 0.001 to 0.01 parts by weight based on the total weight of carboxymethyl cellulose. When mixing the anionic polymer, the absorption rate can be improved by 10,000 to 40,000% (or up to 400 times compared to the particle mass).

At this time, various anionic polymers may be used as the anionic polymer, but polyacrylamide is preferably used.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement them. Additionally, in describing the present invention, if it is determined that a detailed description of a related known function or known configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Additionally, some features presented in the drawings are enlarged, reduced, or simplified for ease of explanation, and the drawings and their components are not necessarily drawn to appropriate scale. However, those skilled in the art will easily understand these details.

Example 1

1kg of wood-derived cellulose powder manufactured by Nippon paper chemicals Co., Ltd. (Japan) was added to a pressure reactor (Lodige, Druvatherm series), and a mixed solvent of isopropyl alcohol/water as a reaction solvent (weight ratio = 6.7:1) was added. After adding 8kg, 60kg of 50% by weight aqueous sodium hydroxide solution, which is an alkalizing agent, was added and reacted with stirring at 20°C for 60 minutes to obtain alkalized cellulose.

Next, a solution of 2 kg of sodium monochloroacetate dissolved in 2 kg of water was introduced into the reactor. At this time, the temperature of the reactor was maintained at 20°C. Once the mixed solution was completely added, the temperature inside the reactor was raised to 70°C and a carboxymethylation reaction was performed for 120 minutes to prepare carboxymethyl cellulose. Then, while maintaining the temperature in the reactor at 30°C, 20 kg of a 99% by weight acetic acid solution, a neutralizing agent, was added and neutralized.

The viscosity of the wood-derived carboxymethyl cellulose prepared in this way was measured by the method of ISO 5351, and the viscosity was measured to be less than 50 cps.

A cellulose derivative mixture was prepared by mixing 9 kg of the wood-derived carboxymethyl cellulose with 1 kg of carboxymethyl cellulose (manufactured by Cekol) with a viscosity of 50,000 cps. Water was mixed with the cellulose derivative mixture and stirred at 70° C. for 30 minutes to obtain a 0.5 A cellulose derivative mixture solution of % by weight was prepared.

20% by weight of citric acid was added based on the cellulose derivative mixture solution, and then stirred at 70°C for 30 minutes. After the stirring was completed, polyamidoamine epichlorohydrin (PAE) was added at a rate of 0.5-2.0% by weight and stirred at 70°C for 30 minutes to prepare absorbent material raw materials.

100 ml of the absorbent material raw material was supplied to a vacuum filter with a diameter of 10 cm, vacuum filtration was performed at 80 kPa, and then dried at a temperature of 40° C. for 48 hours to prepare a film-type highly absorbent material (Figure 4 (a)).

Examples 2 to 7

An experiment was conducted to confirm the effect of mixed use of carboxymethyl cellulose. Carboxymethyl cellulose (50,000 CMC) with a viscosity of 50,000 cps and wood-derived carboxymethyl cellulose (50 CMC) were mixed and used in the same ratio as Table 1 below, and the rest was carried out in the same manner as in Example 1.

50,000CMC(kg) 50CMC(kg) Example 2 0.1 9.9 Example 3 0.3 9.7 Example 4 0.5 9.5 Example 5 1.5 8.5 Example 6 2 8 Example 7 2.5 7.5 Comparative Example 1 10 - Comparative Example 2 - 10

Experimental Example 1

Using the film-type superabsorbent material prepared by the method of Examples 1 to 8 and Comparative Examples 1 to 2, average pore diameter (㎛), porosity (%), apparent density (g/ml), and maximum absorption capacity (g /g) was measured. Here, the porosity was measured using the mercury intrusion method, and the maximum absorption capacity was determined by immersing 10 g of film-type high-absorbency material in distilled water, filtering it after 1 hour, and measuring the weight.

In addition, a film-type highly absorbent material cut to a size of 1 cm

Pore diameter porosity density absorption capacity Area change Example 1 155.0 56.8 0.64 798 38.9 Example 2 34.8 32.4 0.91 135 3.5 Example 3 85.4 51.8 0.88 267 6.8 Example 4 115.1 55.6 0.75 547 18.4 Example 5 161.0 57.5 0.61 657 22.6 Example 6 175.1 61.9 0.52 559 16.5 Example 7 218.4 65.4 0.44 537 11.4 Comparative Example 1 226.8 48.1 0.59 615 12.6 Comparative Example 2 11.5 22.2 0.99 118 1.8

As shown in Table 2, Example 1 of the present invention had a high absorption capacity and pores were uniformly distributed on the surface (Figure 5(a)). However, in Examples 2 and 3, where a small amount of high-viscosity CMC was used, it was confirmed that the absorption capacity was significantly reduced, and that almost no pore formation on the surface occurred (Figure 5(c)).

Even in Example 7, where excessively high viscosity CMC was used, the change in absorption capacity was found to be low, and the pore formation on the surface was confirmed to be uneven (Figure 5(b)). It was confirmed that it was possible to produce an absorbent equivalent or better than that of Comparative Example 1 using only CMC, even when using inexpensive low molecular weight wood-derived CMC. However, in the case of Comparative Example 2, which used only wood-derived low-viscosity CMC, the absorption rate was found to be very low, so it was confirmed that mixing in an appropriate ratio was necessary.

Examples 8 to 15

An experiment was conducted to confirm the results depending on the ratio of the cellulose derivative mixture in the cellulose derivative mixture solution. Water and a cellulose derivative mixture were mixed and used in the ratio shown in Table 3 below, and this was manufactured into a film-type highly absorbent material as in Example 1.

water (kg) Cellulose derivative mixture (kg) Example 1 100 0.5 Example 8 100 0.05 Example 9 100 0.1 Example 10 100 0.3 Example 11 100 One Example 12 100 5 Example 13 100 10 Example 14 100 20

Experimental Example 2

After manufacturing the superabsorbent film according to the method of Examples 8 to 14, its thickness (mm) was measured and visually confirmed to be usable as a film. Whether it could be used as a film was checked by bending the film so that both ends were in contact and checking whether damage occurred.

Thickness (mm) availability Example 1 0.02 O Example 8 0.008 X Example 9 0.011 O Example 10 0.015 O Example 11 0.03 O Example 12 0.05 O Example 13 0.36 X Example 14 1.44 X

As shown in Table 4, it was confirmed that the examples of the present invention were manufactured in a film form with an appropriate thickness. However, in Example 8 using an excessive amount of solvent, although it was possible to form a film, tearing occurred due to the too thin thickness, and in Examples 13 and 14 using a small amount of solvent, the cellulose derivative mixture formed a slurry. Therefore, it was found to be difficult to form into a film. In addition, as shown in Table 4, in the case of Examples 13 and 14, as the slurry was formed as described above, it had no choice but to be manufactured in the form of a thick film, and as a result, damage occurred when bent, making it impossible to form it into a film form. Confirmed.

Examples 15-27

An experiment was conducted to confirm the effects of the type and content of crosslinking agents and polymer additives. The same procedure as Example 1 was carried out, except that the types and contents (% by weight) of the crosslinking agent and polymer additive were added as shown in Table 5 below.

crosslinking agent polymer additives citric acid maleic acid EP PAE P.E.I. starch Example 1 20 - - One - - Example 15 5 - - One - - Example 16 10 - - One - - Example 17 30 - - One - - Example 18 50 - - One - - Example 19 70 - - One - - Example 20 - 20 - One - - Example 21 - - 20 One - - Example 22 20 - - 0.3 - - Example 23 20 - - 0.5 - - Example 24 20 - - 1.5 - - Example 25 20 - - 2 - - Example 26 20 - - - One - Example 27 20 - - - - One

EP: Epichlorohydrin

PAE: Polyamidoamine Epichlorohydrin

PEI: polyethyleneimine

Experimental Example 3

Using the film-type highly absorbent materials prepared in Examples 15 to 27, the maximum absorption capacity (g/g) and area change at maximum absorption (fold) were measured in the same manner as in Experimental Example 1. In addition, in order to check stability after manufacturing the film, it was confirmed whether it could be used as a film in the same manner as in Experimental Example 2.

absorption capacity Area change availability Example 1 798 38.9 O Example 15 138 7.5 X Example 16 651 29.1 O Example 17 719 31.8 O Example 18 648 27.9 O Example 19 448 19.9 X Example 20 619 28.4 O Example 21 645 24.9 O Example 22 591 29.4 X Example 23 618 30.1 O Example 24 649 31.5 O Example 25 430 22.0 X Example 26 715 31.4 O Example 27 742 30.0 O

As shown in Table 6, when the content of the cross-linking agent is lowered, the absorption capacity appears to decrease, and when a cross-linking agent below a certain level is added (Example 15), the formation of the polymer network in the core portion is incomplete, and the absorption capacity is greatly reduced. I was able to confirm that In addition, in the case of Example 19 using an excessive cross-linking agent, it was possible to maintain a certain degree of absorbency, but when produced in a film form, cracks and breaks occurred, making it impossible to form a film.

In Example 22, in which a small amount of polymer additives were used, the absorption amount was maintained, but the shape of the film was not maintained. As shown in Figure 6, cracks occurred on the surface of the film, resulting in defects.

In addition, in Example 25, where an excessive amount of polymer additives were used, the film was not completely dried under the same conditions, making it difficult to form a film.

In addition, even when the types of crosslinking agent and polymer additives were different, there was a certain decrease in water absorption, but it was possible to use it as a film.

Example 28

Absorbent material raw materials were prepared in the same manner as in Example 1 above.

Chitosan was used as a thickener to prepare the shell forming solution. A 0.5% by weight aqueous solution of chitosan was adjusted to pH 4.0-4.5 by adding hydrochloric acid to prepare a shell-forming solution, and the absorbent material raw material was added dropwise at a height of 15cm above the water surface. In order to stabilize the particles inside the chitosan aqueous solution, the reaction was performed at 35°C for 30 minutes.

After the reaction was completed, the chitosan aqueous solution and the particles were separated, and then the particles were washed with ethanol three times and dried at 40°C for 24 hours to prepare a particle-type superabsorbent material (Figure 4(b)).

Examples 29-35

An experiment was conducted to confirm changes in the particle-type superabsorbent material depending on the type of thickener, the concentration (% by weight) of the chitosan aqueous solution, and the dropping height (cm).

Chitosan starch pectin drop height Example 28 0.5 - - 15 Example 29 0.05 - - 15 Example 30 0.1 - - 15 Example 31 0.8 - - 15 Example 32 One - - 15 Example 33 1.2 - - 15 Example 34 - 0.5 - 15 Example 35 - - 0.5 15 Example 36 0.5 - - 5 Example 37 0.5 - - 10 Example 38 0.5 - - 20 Example 39 0.5 - - 30 Example 40 0.5 - - 40

Experimental Example 4

Using the particle-type highly absorbent materials prepared in Examples 28 to 40, the average particle diameter (mm), size deviation (mm), specific surface area (㎡/g), porosity (%) and absorption capacity (g) by nitrogen adsorption were measured. /g) were measured respectively. At this time, the size deviation represents the difference between the distribution of 80% by weight excluding the small 10% by weight and the large 10% by weight and the median value, which can represent the difference in particle size that includes 80% by weight of particles from the average particle size. there is. If this size deviation is small, it means that particles of uniform size are formed.

As Comparative Example 3, sludge was prepared by mixing 20% by weight of a cellulose derivative mixture with 100 parts by weight of water as in the existing method (see Example 7), and then dried and pulverized to prepare a particle-type absorbent material.

average particle size size deviation specific surface area porosity absorption capacity Example 28 0.92 0.08 75.5 81.2 856 Example 29 - - - - - Example 30 0.82 0.11 57.5 76.8 657 Example 31 0.98 0.16 55.9 78.8 648 Example 32 1.01 0.18 55.1 65.1 545 Example 33 - - - - - Example 34 0.91 0.09 74.9 77.8 669 Example 35 0.92 0.08 74.1 80.8 719 Example 36 - - - - - Example 37 1.25 0.09 68.7 74.1 667 Example 38 1.01 0.09 68.4 72.1 684 Example 39 0.84 0.14 65.4 71.1 657 Example 40 0.45 0.21 66.9 34.8 158 Comparative Example 3 0.95 0.54 49.1 46.5 228

As shown in Table 8, there was a difference in absorption capacity depending on the content of chitosan. In the case of Example 28, it was found to have a high absorption capacity due to a high specific surface area. As a result of enlarged observation, it was confirmed that, as shown in FIG. 7, it had a uniform size but had many wrinkles on the surface, allowing it to have a high specific surface area.

However, when using a chitosan solution with a concentration below a certain level as in Example 29, it was confirmed that the production of a particle-type absorber was impossible because a shell was not formed. In addition, in the case of Example 33 using a high concentration chitosan solution, the core-shell forming solution had excessive viscosity, which prevented the absorbent material raw materials from penetrating into the solution, making it difficult to form a particle-type absorbent material. .

In addition, in Example 36, where the dropping height was lowered, the absorbent material raw material did not penetrate into the chitosan solution, making it impossible to form particles, and in Examples 39 and 40, where the dropping height was increased, the liquid of the absorbent material raw material when in contact with the solution. As the enemy was destroyed, size deviation increased and absorbency decreased.

In the case of Comparative Example 3, which was prepared by forming a slurry and then pulverizing it as in the existing method, it was confirmed that it was difficult to form uniform particles because particles of various sizes were generated during pulverization.

Experimental Example 5

The absorption capacity for urine was confirmed using the particle-type highly absorbent material prepared by the method of Example 28. In addition, in order to confirm the effect of the anionic polymer, anionic polyacrylamide (A-PAM) was mixed and used in the ratio as shown in Table 9 below. As a comparative example, an acrylic acid-based absorbent (average pore diameter 153.1㎛, porosity 54.4%) previously used as a urine absorbent was used. A 0.9% NaCl solution was used as artificial urine.

Particle-type highly absorbent material A-PAM Example 41 Example 28 - Example 42 Example 28 0.001 Example 43 Example 28 0.002 Example 44 Example 28 0.003 Example 45 Example 28 0.004 Comparative Example 4 acrylic acid -

The results of the experiment as described above are shown in Figure 8. Even when only Example 28 of the present invention (Example 41) was used, it was found to have the same absorbency for urine as Comparative Example 4, a conventional chemical synthesis product, and when it contained 0.003% by weight polyacrylamide, it was found to have an absorbency against urine. Absorbency was found to be improved by up to 400% or more.

As the specific parts of the present invention have been described in detail above, it is clear to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. will be. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (18)

(a) preparing a cellulose derivative mixture solution by mixing two or more types of cellulose derivatives with different viscosities;
(b) mixing a cross-linking agent with the cellulose derivative mixture solution to form a porous polymer network;
(c) preparing an absorbent material raw material by mixing a polymer additive with the cellulose derivative mixture solution in which the porous polymer network is formed; and
(d) forming the absorbent material raw material;
In the method of manufacturing a highly absorbent material using a cellulose derivative containing,
The cellulose derivative mixture is a mixture of first carboxymethyl cellulose with a viscosity of 10,000 to 100,000 cps and second carboxymethyl cellulose with a viscosity of 10 to 300 cps.
delete According to paragraph 1,
The first carboxymethyl cellulose and the second carboxymethyl cellulose have a degree of substitution of 0.4 or more,
The cellulose derivative mixture is a method of producing a highly absorbent material using a mixture of 5 to 20% by weight of first carboxymethylcellulose and 80 to 95% by weight of second carboxymethylcellulose.
According to paragraph 1,
The second carboxymethyl cellulose is a method of producing a highly absorbent material using a cellulose derivative derived from wood.
According to paragraph 1,
A method of producing a highly absorbent material using a cellulose derivative, wherein the cellulose derivative mixture solution is a mixture of 0.1 to 5 parts by weight of the cellulose derivative mixture relative to 100 parts by weight of the solvent.
According to clause 5,
The solvent is a method of producing a highly absorbent material using a cellulose derivative containing at least one selected from the group of water, ethanol, ethanol, and IPA.
According to paragraph 1,
The cross-linking agent is an anionic cross-linking agent, and the polymer additive is an anionic or cationic additive, and a method of manufacturing a highly absorbent material using a cellulose derivative using the same.
In clause 7,
The anionic crosslinking agent is a highly absorbent material using a cellulose derivative containing at least one selected from the group consisting of citric acid, maleic acid, epichlorohydrin, and aluminum sulfate. Manufacturing method.
In clause 7,
The cationic additives include starch, gum, chitin, chitosan, glycan, galactan, pectin, mannan, dextrin, acrylic acid, methacrylic acid, polyvinyl alcohol, polyamine, polyethyleneimine, polyethylene oxide, polypropylene oxide, polyurethane, and A method for producing a highly absorbent material using a cellulose derivative comprising at least one selected from the group consisting of polyamidoamine epichlorohydrin.
In clause 7,
A method for producing a highly absorbent material using a cellulose derivative, wherein the anionic crosslinking agent is mixed in an amount of 10 to 50 parts by weight based on 100 parts by weight of the solvent contained in the cellulose derivative mixture solution.
In clause 7,
A method for producing a highly absorbent material using a cellulose derivative, wherein the polymer additive is mixed in an amount of 0.5 to 2.0 parts by weight based on 100 parts by weight of the solvent contained in the cellulose derivative mixture solution.
According to paragraph 1,
The step (d) of molding the absorbent material raw material,
(i) forming the absorbent material into a certain shape through filtration, coating, or spraying; and
(ii) separating the solvent in the molded absorbent material raw material and drying the solid content to form a film;
A method of manufacturing a highly absorbent material using a cellulose derivative containing.
According to paragraph 1,
The step (d) of molding the absorbent material raw material,
(1) preparing a solution for core-shell formation by mixing 0.1 to 1% by weight of a shell-forming additive in a solvent;
(2) adding the absorbent material raw materials dropwise to the core-shell forming solution to form highly absorbent particles in the shell forming solution; and
(3) separating the superabsorbent particles, then washing and drying;
A method of manufacturing a highly absorbent material using a cellulose derivative containing.
A highly absorbent material using a cellulose derivative manufactured by the method of any one of claims 1, 3 to 11.
According to clause 14,
The highly absorbent material is a highly absorbent material using a cellulose derivative having a porosity of 50 to 85%.
According to clause 14,
The highly absorbent material is a highly absorbent material that additionally contains 0.001 to 0.005% by weight of anionic polymer based on the total weight.
A film-type highly absorbent material using a cellulose derivative prepared by the method of claim 12.
A particle-type highly absorbent material using a cellulose derivative prepared by the method of claim 13.