KR20210067312A - Biodegradable and superabsorbent polymer based on polyitaconic acid and method for preparing the same - Google Patents

Abstract

The present invention relates to a polyitaconic acid graft copolymer prepared by polymerization and crosslinking of a mixture including itaconic acid, starch, an acrylic acid derivative and a crosslinking agent. The polyitaconic acid graft copolymer according to the present invention has water solubility and biodegradability, and thus is a superabsorbent biodegradable polymer causing low environmental burden, when being discarded. In addition, since the polyitaconic acid graft copolymer is prepared by using eco-friendly materials as main ingredients, hygienic products using the same is not harmful to the human body and reduces skin irritation. Further, since the polyitaconic acid graft copolymer uses cheap raw materials, it is possible to develop products having high cost competitiveness by reducing the production cost.

Description

Polyitaconic acid-based biodegradable superabsorbent polymer and method for manufacturing the same {BIODEGRADABLE AND SUPERABSORBENT POLYMER BASED ON POLYITACONIC ACID AND METHOD FOR PREPARING THE SAME}

The present invention relates to a polyitaconic acid-based biodegradable superabsorbent polymer and a manufacturing method thereof, and more particularly, to a biodegradable superabsorbent polymer prepared based on a biodegradable monomer such as itaconic acid and a manufacturing method thereof is about

Super absorbent polymer has high water absorption and water retention properties, so it is used in a wide range of materials, starting with hygiene products, agriculture, horticulture, distribution materials, civil engineering, construction, medical care, and toys. In particular, recently, research is underway to utilize an absorbent polymer with appropriate gel properties and adhesion as a component material for various electronic devices.

In the synthesis of superabsorbent polymers, acrylic acid-based resins such as sodium polyacrylate crosslinked products refined from crude oil are used as raw materials, but acrylic acid-based resins are difficult to decompose and when used in disposable diapers, there is concern about causing environmental problems when discarded. is becoming Therefore, recently, attempts have been made to use a cellulose derivative as a material having biodegradability and excellent absorbency, and in particular, the use of carboxymethyl cellulose containing a carboxylate in its structure has been studied. For example, a method of chemically crosslinking carboxymethyl cellulose and a method of crosslinking using radiation crosslinking are known. However, in the above technology, when only a cellulose derivative is used as a starting material, there is a problem in that the manufacturing cost is high, and since the bond between the crosslinking part and carboxymethylcellulose is an ether bond, it is chemically stable and there is a problem in terms of biodegradability.

On the other hand, a method for synthesizing a superabsorbent polymer with biodegradability, absorption capacity and absorption rate comparable to existing acrylic acid-based resins using cellulose, chitin, and chitosan as raw materials has been introduced. The solubility was very low, so it was effective only for some natural materials such as carboxymethyl cellulose (CMC). However, this also had a problem in that the solubility of the solvent was low, so a long time for dissolution and dispersion at high temperature was required, and the yield of the resulting resin was also low. In addition, a method of using succinic anhydride as a method of crosslinking a cellulosic material with an ester bond exhibiting high biodegradability rather than an ether bond has been announced, but since the content of sodium carboxylate salt contained in the absorbent material is small, the absorption rate There was a problem in that only a crosslinked product having a late rate could be obtained. Therefore, it is required to develop a material that can replace the sodium polyacrylate crosslinked product as a material that can be applied to hygiene products, thereby satisfying biodegradability and environmental friendliness, and developing a polymer having high absorbency and absorption rate.

On the other hand, IA (Itaconic Acid) is a water-soluble monomer having two Carboxylic Acid groups in its molecule. It is a bio-Mass-derived material produced through fermentation, and its chemical properties and safety have been proven, so IA and IA derivatives are used in the chemical industry and medical field. is an expanding trend. In particular, recently, through radical polymerization and crosslinking reaction based on IA,

The manufactured PIA (Poly Itaconic Acid) Hydro-gel resin has excellent water absorption and degradability, so it is expected to expand its use in various fields such as improvement materials that increase the water retention of the soil. However, these PIA Hydrogel resins have disadvantages in that mechanical strength, especially compressive strength in a state where moisture is absorbed and expanded, that is, gel strength, is weak, and the absorption capacity under pressure is also poor, so improvement is required.

On the other hand, PVA resin is a water-soluble resin universally used in various applications such as film adhesive, has biocompatibility and biodegradability, and has excellent mechanical properties, so various studies are in progress as a gel material for absorbent resin. However, these PVA-based gel resins have limited absorption capacity, which is an obstacle to application development.

An object of the present invention is to solve the above problems, and to provide a biodegradable superabsorbent polymer based on polyitaconic acid containing starch, which has water solubility and biodegradability and thus has a low environmental burden due to disposal.

In addition, when applied to hygiene products, it is possible to provide a biodegradable superabsorbent polymer that is harmless to the human body and reduces skin irritation.

In addition, by using a low-cost raw material, it is possible to provide a material useful for developing an absorbent product advantageous in terms of price competitiveness by reducing manufacturing cost.

According to one aspect of the invention, itaconic acid; starch; acrylic acid derivatives; and a crosslinking agent; a polyitaconic acid graft copolymer prepared by polymerizing and crosslinking a mixture comprising a copolymer is provided.

In addition, the polymerization reaction includes a radical reaction and a condensation reaction, the radical reaction is performed by a radical reaction of at least one vinyl group selected from the group consisting of itaconic acid and acrylic acid derivatives, and the condensation reaction is a hydroxyl group of the starch and esterification with at least one carboxyl group selected from the group consisting of itaconic acid and acrylic acid derivatives.

In addition, the crosslinking reaction may be carried out by radical reaction of at least one vinyl group selected from the group consisting of itaconic acid and acrylic acid derivatives and a vinyl group of the crosslinking agent.

In addition, the starch may include at least one selected from the group consisting of corn starch, waxy corn starch, tapioca starch, potato starch, sweet potato starch, wheat starch, rice starch, sago starch, and modified starches thereof.

In addition, the modified starch may include at least one selected from the group consisting of oxidized starch, acid-treated starch, ester starch, ether starch, phosphoric acid cross-linked starch, and acetyladipic acid starch.

In addition, the starch is modified corn starch, and the modified corn starch is oxidized corn starch, hydroxyethylated dent corn starch, hydroxypropylated cross-linked dent corn starch, and hydroxypropylated cross-linked refined wax. ) may include one or more selected from the group consisting of corn starch.

In addition, the itaconic acid may be at least one compound selected from the group consisting of the following structural formulas 1 to 3.

[Structural Formula 1]

[Structural Formula 2]

[Structural Formula 3]

In the above structural formulas 1 to 3,

R ₁ and R ₂ are the same as or different from each other, and each independently represents a hydrogen atom, a C1 to C18 alkyl group, a C5 to C18 cyclic alkyl group, or a C6 to C18 aryl group,

R ₃ is each independently a valence bond, a C1 to C18 alkylene group, a C5 to C18 cyclic alkylene group, or a C6 to C18 arylene group.

In addition, the acrylic acid derivative may be a compound represented by the following structural formula (4).

[Structural Formula 4]

In Structural Formula 4,

R ₄ is a hydrogen atom or a C1 to C3 alkyl group.

In addition, the acrylic acid derivative may include at least one selected from the group consisting of acrylic acid, methacrylic acid, and methyl methacrylic acid.

In addition, the polyitaconic acid graft copolymer may include at least one vinyl polymer selected from the group consisting of itaconic acid and acrylic acid derivatives; starch grafted to the vinyl polymer; polyitaconic acid grafted to the starch; a polyacrylic acid derivative grafted onto the starch; Itaconic acid-acrylic acid derivative copolymer grafted to the starch; and a crosslinking agent for crosslinking at least one selected from the group consisting of the vinyl polymer, polyitaconic acid, polyacrylic acid derivative, and the itaconic acid-acrylic acid derivative copolymer.

In addition, the graft of the polyitaconic acid graft copolymer may be by at least one selected from the group consisting of an ester bond, an ionic bond, and a hydrogen bond.

In addition, the crosslinking agent is polyethylene glycol diacrylate (PEGDA), 1,6-hexanediol acrylate (HDDA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimeth Acrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol Dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, N,N'-methylenebisacrylamide (N,N'-Methylenebisacrylamide), N,N'-ethylenebisacryl It may include at least one selected from the group consisting of amide (N,N'-Ethylenebisacrylamide) and N,N'-propylenebisacrylamide (N,N'-Propylenebisacrylamide).

In addition, the polyitaconic acid graft copolymer may further include a surface crosslinking layer.

According to another aspect of the present invention, there is provided an absorbent material comprising the polyitaconic acid graft copolymer.

According to another aspect of the present invention, there is provided a method for preparing the polyitaconic acid graft copolymer, comprising the step of polymerizing by mixing starch, itaconic acid, an acrylic acid derivative, a crosslinking agent and an initiator.

In addition, the method for preparing the polyitaconic acid graft copolymer includes the steps of: (a) preparing a mixed solution containing starch, itaconic acid, an acrylic acid derivative, a crosslinking agent and a neutralizing agent; and (b) adding an initiator to the mixed solution and reacting to prepare the polyitaconic acid graft copolymer.

In addition, the initiator is a peroxide, azo compound, azobisisobutyronitrile (AIBN), persulfate, ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide (H ₂ O ₂ ) and tertiobutylhydroperoxide (tertiobutylhydroperoxide) It may include one or more selected from the group consisting of.

In addition, the neutralizing agent may include at least one selected from the group consisting of a non-metal hydroxide, ammonium hydroxide, an organic base compound containing an alkyl amine, and an organic compound containing a hydroxyl group.

Also, after step (b), the step (c) of preparing a polyitaconic acid graft copolymer having a surface crosslinking layer formed thereon by adding and reacting the polyitaconic acid graft copolymer and a surface crosslinking solution may be further included.

In addition, the surface crosslinking solution is an alcohol compound; alkylene carbonate compounds; polyamine compounds; epoxy compounds; organic carboxylic acid compounds; polyvalent metal salts; And inorganic compounds; may include at least one selected from the group consisting of.

The polyitaconic acid graft copolymer and the preparation method thereof of the present invention have water solubility and biodegradability, so that the environmental burden due to disposal is small, and it is possible to provide a biodegradable and superabsorbent polymer having high absorbency and absorption rate.

In addition, since it is manufactured using a non-toxic material as a main raw material, when it is applied to hygiene products, it is friendly to the human body and can reduce skin irritation.

In addition, by using low-cost raw materials, it is possible to develop products advantageous in price competitiveness by reducing manufacturing costs.

1 is an FT-IR analysis result of polymers according to Example 1 and Comparative Examples 1 and 2.
2 is a TGA analysis result of the polymers according to Example 1 and Comparative Examples 1 and 2.
3 is an SEM analysis image of Comparative Example 1.
4 is an SEM analysis image of Comparative Example 2.
5 is an SEM analysis image of Example 1.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Also, when it is stated that a component is “on another component”, “formed on another component” or “stacked on another component”, it is directly applied to the front or one surface of the other component. It may be attached and formed or stacked, but it will be understood that other components may be further present in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, the polyitaconic acid graft copolymer of the present invention will be described.

The present invention is itaconic acid; starch; acrylic acid derivatives; and a crosslinking agent; a polyitaconic acid graft copolymer prepared by polymerizing and crosslinking a mixture comprising a copolymer is provided.

The polymerization reaction includes a radical reaction and a condensation reaction, the radical reaction is performed by a radical reaction of at least one vinyl group selected from the group consisting of itaconic acid and acrylic acid derivatives, and the condensation reaction is performed with a hydroxyl group of the starch , it may be carried out by an esterification reaction with at least one carboxyl group selected from the group consisting of itaconic acid and acrylic acid derivatives.

The crosslinking reaction may be performed by radical reaction of at least one vinyl group selected from the group consisting of itaconic acid and acrylic acid derivatives and a vinyl group of the crosslinking agent.

The starch may include at least one selected from the group consisting of corn starch, waxy corn starch, tapioca starch, potato starch, sweet potato starch, wheat starch, rice starch, sago starch, and modified starches thereof.

The modified starch may include at least one selected from the group consisting of oxidized starch, acid-treated starch, ester starch, ether starch, phosphoric acid cross-linked starch, and acetyladipic acid starch.

The starch is modified corn starch, and the modified corn starch is oxidized corn starch, hydroxyethylated dent corn starch, hydroxypropylated crosslinked dent corn starch and hydroxypropylated crosslinked waxy. It may include one or more selected from the group consisting of corn starch, preferably oxidized corn starch.

The itaconic acid may be at least one compound selected from the group consisting of the following structural formulas 1 to 3.

[Structural Formula 1]

[Structural Formula 2]

[Structural Formula 3]

In the above structural formulas 1 to 3,

R ₁ and R ₂ are the same as or different from each other, and each independently represents a hydrogen atom, a C1 to C18 alkyl group, a C5 to C18 cyclic alkyl group, or a C6 to C18 aryl group,

R ₃ is each independently a valence bond, a C1 to C18 alkylene group, a C5 to C18 cyclic alkylene group, or a C6 to C18 arylene group.

The acrylic acid derivative may be a compound represented by the following structural formula (4).

[Structural Formula 4]

In Structural Formula 4,

R ₄ is a hydrogen atom or a C1 to C3 alkyl group.

The acrylic acid derivative may include at least one selected from the group consisting of acrylic acid, methacrylic acid and methyl methacrylic acid.

The polyitaconic acid graft copolymer may include at least one vinyl polymer selected from the group consisting of itaconic acid and acrylic acid derivatives; starch grafted to the vinyl polymer; polyitaconic acid grafted to the starch; a polyacrylic acid derivative grafted onto the starch; Itaconic acid-acrylic acid derivative copolymer grafted to the starch; and a crosslinking agent for crosslinking at least one selected from the group consisting of the vinyl polymer, polyitaconic acid, polyacrylic acid derivative, and the itaconic acid-acrylic acid derivative copolymer.

The bonding structure of the polyitaconic acid graft copolymer can be grasped with reference to Schemes 1 to 4 below. The polyitaconic acid graft copolymer may include a copolymer generated through a reaction as in Scheme 1, or an acrylic acid derivative and A-Graft or B-graft may be combined with oxidized starch as shown in Scheme 2 below, In addition, similar binding to itaconic acid may be possible. In addition, as shown in Scheme 3 below, since itaconic acid in a trace amount retains acid despite the addition of alkali such as NaOH, the oxidized starch and the itaconic acid may include a Starch-semi-itaconate copolymer produced through an esterification reaction. Finally, as shown in Scheme 4 below, a physical bonding structure generated through electrostatic ionic bonding or hydrogen bonding between starch, itaconic acid and acrylic acid derivatives may also be included.

[Scheme 1]

[Scheme 2]

[Scheme 3]

[Scheme 4]

The polyitaconic acid graft copolymer may be grafted by at least one selected from the group consisting of an ester bond, an ionic bond, and a hydrogen bond.

The graft is a chemical bond through an esterification reaction of a functional group included in each resin, such as a hydroxyl group of the starch, a carboxy group or hydroxyl group of the itaconic acid, a carboxy group or a hydroxyl group of the acrylic acid derivative, an ionic bond through an ionic bond, and physically It may be by at least one selected from the group consisting of linked physical bonds.

Preferably, the graft comprises: an ester bond formed by the reaction of a hydroxy group of the starch with a carboxy group of the itaconic acid or acrylic acid derivative; _{an ionic bond between a cation (-OH 2} ⁺ ) formed by bonding a hydroxy group of the starch with a proton and ^{an anion (-COO -} ) generated by dissociation of a proton by a carboxy group of the itaconic acid or acrylic acid derivative; and a hydrogen bond formed by the reaction of one or more oxygen atoms selected from the group consisting of starch, itaconic acid and acrylic acid derivatives and one or more hydrogen atoms selected from the group consisting of starch, itaconic acid and acrylic acid derivatives; It may be by at least one selected from

The crosslinking agent is polyethylene glycol diacrylate (PEGDA), 1,6-hexanediol acrylate (HDDA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylic rate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol di Methacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, N,N′-methylenebisacrylamide (N,N′-Methylenebisacrylamide), N,N′-ethylenebisacrylamide (N,N'-Ethylenebisacrylamide) and N,N'-propylenebisacrylamide (N,N'-Propylenebisacrylamide) may include at least one selected from the group consisting of.

The polyitaconic acid graft copolymer may further include a surface crosslinking layer.

The polyitaconic acid graft copolymer may be highly absorbent.

The polyitaconic acid graft copolymer may be biodegradable.

The present invention provides an absorbent material comprising the polyitaconic acid graft copolymer.

The present invention provides a hygiene product comprising the absorbent material.

Hereinafter, a method for producing the polyitaconic acid graft copolymer of the present invention will be described.

The method for preparing the polyitaconic acid graft copolymer of the present invention may include mixing and reacting starch, itaconic acid, an acrylic acid derivative, a crosslinking agent and an initiator; and the preparation method will be described below step by step.

First, a mixed solution containing starch, itaconic acid, an acrylic acid derivative, a crosslinking agent and a neutralizing agent is prepared (step a).

The starch may include at least one selected from the group consisting of corn starch, waxy corn starch, tapioca starch, potato starch, sweet potato starch, wheat starch, rice starch, sago starch, and modified starches thereof, preferably modified Corn starch may be included, and more preferably, oxidized corn starch may be included.

The crosslinking agent is polyethylene glycol diacrylate (PEGDA), 1,6-hexanediol acrylate (HDDA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylic rate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol di Methacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, N,N′-methylenebisacrylamide (N,N′-Methylenebisacrylamide), N,N′-ethylenebisacrylamide (N,N'-Ethylenebisacrylamide) and N,N'-propylenebisacrylamide (N,N'-Propylenebisacrylamide) may include at least one selected from the group consisting of.

Before polymerizing the itaconic acid, it is preferable to neutralize the itaconic acid with the neutralizing agent. The neutralizing agent can be used to convert the acidic monomer to any base, such as a monovalent inorganic base, for example M ⁺ [OH ⁻ ] _x (where M represents a cationic moiety selected from sodium, potassium, lithium and x represents a neutralizing salt It can be neutralized using the provided value). In addition, organic compounds including non-metal hydroxides such as ammonium hydroxide, as well as primary amines (eg alkyl amines such as monomethyl amine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine) It is possible to use a basic compound and/or an organic compound containing a hydroxyl (OH) group functional group (eg ethylene glycol).

The amount of neutralization can be adjusted to provide less than complete neutralization of acidic groups present in the polyitaconic acid of the present application. For example, for the representative monomer itaconic acid, it is understandable that complete neutralization would require 2 moles of neutralizing agent for each mole of itaconic acid. That is, 2 moles of sodium hydroxide will provide complete neutralization of 1 mole of itaconic acid, and any amount of sodium hydroxide less than 2 moles will provide the desired result of partial neutralization. When a divalent base is used to neutralize itaconic acid, the amount of divalent base selected to completely neutralize itaconic acid will be 1.0 mole of divalent base for each mole of itaconic acid, and for partial neutralization, less than 1 mole of divalent base is applied to The itaconic acid monomer can be partially neutralized.

The neutralizing agent may be an organic base compound containing an amine group and an organic compound containing a hydroxyl group, preferably sodium hydroxide solution.

Finally, an initiator is added to the mixed solution and reacted to prepare the polyitaconic acid graft copolymer (step b).

The initiator may include at least one selected from the group consisting of a free radical initiator, a water-soluble radical initiator, and a water-soluble initiator. Radical initiation can be effected using, for example, peroxides and azo compounds such as azobisisobutyronitrile (AIBN), preferably water-soluble radical initiators, wherein the selected initiator is combined with deionized water or a water-miscible polar solvent. It can be prepared in solution by dissolving it in Water-soluble initiators may include persulfates such as ammonium persulfate, sodium persulfate and potassium persulfate, including mixtures thereof. In addition, as the water-soluble initiator, hydrogen peroxide (H ₂ O ₂ ), tertiobutyl hydroperoxide, and a water-soluble azo initiator may be included.

After step (b), the step (c) of preparing a polyitaconic acid graft copolymer having a surface crosslinking layer formed thereon by adding and reacting the polyitaconic acid graft copolymer and a surface crosslinking solution may be further included.

The surface crosslinking solution is polyethylene glycol, monopropylene glycol, 1,3-propanediol, dipropylene glycol, 2,3,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerol, polyglycerol, 2-butene polyhydric alcohol compounds such as -1,4-diol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,2-cyclohexanedimethanol; alkylene carbonate compounds such as ethylene carbonate, propylene carbonate, butylene carbonate, isobutylene carbonate, glycerol carbonate, and trimethyl carbonate; polyamine compounds such as ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine and polyamide polyamine; epoxy compounds such as ethylene glycol diglycidyl ether and glycidol; organic carboxylic acid compounds; polyvalent metal salts; And inorganic compounds; may include one or more selected from the group consisting of, but is not limited thereto.

The polyvalent metal salt is aluminum chloride, polyaluminum chloride, aluminum sulfate, aluminum acetate, potassium aluminum bissulfate, aluminum sodium bissulfate, potassium alum, ammonium alum, sodium alum, sodium aluminate, calcium chloride, calcium acetate, magnesium chloride, magnesium sulfate, It may include at least one selected from the group consisting of magnesium acetate, zinc chloride, zinc sulfate, zinc acetate, zirconium chloride, zirconium sulfate and zirconium acetate.

The inorganic compound may include at least one selected from the group consisting of silica, clay, alumina, silica-alumina composite, titania, zinc oxide, aluminum sulfate, and mixtures thereof.

In the surface crosslinking, it is possible to use the surface crosslinking solution alone, but in general, a solvent may be used to prepare a mixed solution for use. The solvent used therein may be water or polyhydric alcohols such as methanol, but is not limited thereto.

When the surface crosslinking solution is uniformly sprayed on the polyitaconic acid graft copolymer and then exposed to a high temperature, crosslinking (condensation polymerization) proceeds on the surface of the copolymer, so that the crosslinking density of the surface is increased compared to the inside. This makes the absorbency under pressure (AUL) and permeability (SPT) good.

[Example]

Hereinafter, the present invention will be described in more detail through examples. However, this is for illustrative purposes only, and the scope of the present invention is not limited thereto.

Example 1: Polyitaconic acid-starch-polyacrylic acid graft copolymer (IA + OS + AA)

In a 1L beaker, 50g of Acrylic acid as a monomer, 45g of Itaconic acid and 5g of Oxidized Corn Starch, 0.1g and 1 of Poly(ethylene glycol) diacrylate as a crosslinking agent 0.1 g of ,6-hexanediol diacrylate and 80 g of water were mixed and stirred. Then, while neutralizing with 80 g of 50% caustic soda (NaOH), the rate was adjusted so that the heat of neutralization did not exceed 90° C. After naturally cooling the temperature of the monomer solution to 60° C. _{, 0.5 g of sodium persulfate (Na 2} S ₂ O ₈ ) as an initiator was added and stirred for 3 minutes. The monomer solution stirred with the initiator was poured into a tray with a wide surface, the cover was closed, and then placed in a dryer set at 50° C. to proceed with polymerization. After 12 hours, the tray cover was removed, dried at 60° C. for 4 hours, removed from the tray, put in a freezer, and frozen to prepare a Super Absorbent Polymer (SAP) sheet.

The frozen superabsorbent polymer (SAP) sheet was subjected to a strong impact to make it into small pieces and then pulverized with a coarse grinder. Put the coarsely pulverized SAP in a dryer set at 60℃ and dry it for 4 hours to remove almost any moisture, classify the dried SAP to 300~600um using a standard sieve to prepare Base-SAP, and grind large particles again to classify was repeated.

For surface crosslinking of the Base-SAP, 5 g of 1,4-butanediol, 1 g of aluminum sulfate (18 hydrate), 1 g of fumed silica (Konasil K200), and 1 g of oxalic acid were dissolved in 40 g of water and 53 g of methanol, respectively. was prepared. 100 g of the Base-SAP was put into a round flask, and the surface cross-linking solution was uniformly sprayed at 15 wt% compared to Base-SAP while stirring. The base-SAP with the surface cross-linking layer was placed in a rotating barrel set at 170° C. and heated while rotating for about 1 hour to obtain a polyitaconic acid-starch-polyacrylic acid graft copolymer (IA + OS + AA).

Example 2: Polyitaconic acid-starch-polyacrylic acid graft copolymer (IA + ST + AA)

Polyitaconic acid-starch-polyacrylic acid graft copolymer in the same manner as in Example 1, except that 5 g of Corn Starch was used instead of 5 g of Oxidized Corn Starch in Example 1 (IA + ST + AA) was prepared.

Comparative Example 1: Polyacrylic acid polymer (AA)

In Example 1, 50 g of acrylic acid, 45 g of itaconic acid and 5 g of oxidized corn starch, 0.1 g of polyethylene glycol diacrylate, 0.1 g of 1,6-hexanediol acrylate and 80 g of water were mixed as a crosslinking agent, and shodium persulfate ( Instead of adding 0.5 g of Na ₂ S ₂ O ₈ ), 100 g of acrylic acid, 0.1 g of polyethylene glycol diacrylate as a crosslinking agent, 0.1 g of 1,6-hexanediol acrylate, and 120 g of water are mixed, and Shodium persulfate ( Na ₂ S ₂ O ₈ ) A polyacrylic acid polymer (AA) was prepared in the same manner as in Example 1, except that 0.1 g was added.

Comparative Example 2: Poly itaconic acid polymer (IA)

In Example 1, 50 g of acrylic acid, 45 g of itaconic acid and 5 g of oxidized corn starch, 0.1 g of polyethylene glycol diacrylate, 0.1 g of 1,6-hexanediol acrylate, and 80 g of water were mixed as a crosslinking agent, and 50% caustic soda (NaOH). ) instead of neutralizing with 80 g, mix 100 g of itaconic acid, 0.3 g of N,N′-Methylenebis(acrylamide) as a crosslinking agent, and 100 g of water, and 50% caustic soda (NaOH) A polyitaconic acid polymer (IA) was prepared in the same manner as in Example 1, except for neutralization at 60 g.

Comparative Example 3: Polyacrylic acid-polyitaconic acid graft polymer (AA+IA)

In Example 1, instead of mixing 50 g of acrylic acid, 45 g of itaconic acid and 5 g of oxidized corn starch, 0.1 g of polyethylene glycol diacrylate and 0.1 g of 1,6-hexanediol acrylate and 80 g of water as a crosslinking agent, 50 g of acrylic acid, itaconic acid Polyacrylic acid-polyitaconic acid graft polymer (Polyacrylic acid-polyitaconic acid graft polymer (P) in the same manner as in Example 1 except that 50 g of acid, 0.1 g of polyethylene glycol diacrylate, 0.1 g of 1,6-hexanediol acrylate, and 80 g of water were mixed as a crosslinking agent AA+IA) was prepared.

[Test Example]

Test Example 1: FT-IR analysis

1 is an FT-IR analysis result of polymers according to Example 1 and Comparative Examples 1 and 2. The analysis was performed using an FT-IR instrument (manufacturer: Thermo Scientific, model name: Nicolet 380).

According to FIG. 1, in the polymers according to Example 1 and Comparative Examples 1 and 2, a carbonyl group peak was observed in the vicinity ^{of about 1700 cm −1 in common.}

Further will a band around 3000cm ^-1 and 3800cm ^-1 are formed wider in the vicinity of the resulting -OH groups of the starch oxidation, about 2918cm ^-1, 1599cm ^-1, 1404cm ^-1 and 1025cm ^-1 peak aliphatic CH of each oxidized starch, This is due to COO- (asymmetric), COO- (symmetric) and CO functional groups.

In addition, about ^{2903 cm -1, 1580 cm -1,} 1408 cm -1 and 1030cm ^-1 peak, aliphatic CH, COO- (asymmetric), COO- (symmetrically) related to the structure of the grafted polymer according to the first embodiment, respectively, and This is due to the CO functional group. And the peak at about 1728 cm ^-1 is due to the ester carbonyl band in which a crosslinking reaction occurred between the -OH functional group of oxidized starch and the -COOH functional group of polyitaconic acid (PIA) or polyacrylic acid (PAA) did it

Test Example 2: Thermogravimetric analysis (TGA) analysis

2 is a TGA analysis result of the polymers according to Example 1 and Comparative Examples 1 and 2. The analysis was measured using a thermogravimetric analysis (TGA) instrument (manufacturer: METTLER TOLEDO, model name: TGA 2).

According to FIG. 2, the decomposition temperature of Comparative Example 1 (AA) was 440°C, Example 1 (AA+OS+IA) was 361°C, and Comparative Example 2 (IA) was 283°C, respectively. The lower the decomposition temperature, the easier biodegradation can occur.

Test Example 3: Scanning Electron Microscopy (SEM) Analysis

3 is a SEM analysis image of Comparative Example 1, FIG. 4 is Comparative Example 2, and FIG. 5 is Example 1. The analysis was taken using an SEM instrument (manufacturer: TESCAN, model name: Vega 3).

According to FIGS. 3 to 5 , the size of the cracks on the sample surface was large in the order of Comparative Example 2 (IA), Comparative Example 1 (AA), and Example 1 (AA+OS+IA). It was confirmed that this was related to the surface area that could come into contact with moisture during biodegradation by microorganisms.

Test Example 4: Analysis of polymer performance

Table 1 below describes the water holding capacity (CRC), absorbency under pressure (AUL, @0.3psi), liquid permeability (SPT) and biodegradability (using KSMISO14851) of the polymers according to Examples 1 and 2 and Comparative Examples 1 to 3, respectively. did.

Maintenance capacity (CRC) measurement

Put 200 ml of distilled water in a beaker, add and dissolve NaCl so that it becomes a 0.9 wt.% NaCl aqueous solution, and then add 0.2 g of the polymer according to Examples 1 and 2 and Comparative Examples 1 to 3 of the present invention by quantitative introduction into the dried tea bag After immersion in a beaker containing NaCl aqueous solution for 30 minutes, centrifuge for 3 minutes with a centrifuge 300gravity to completely remove moisture simply attached to the surface, and then accurately measure the weight of the swollen tea bag as shown in Equation 1 The Swelling Ratio was calculated by using this method, and the average value was calculated after measuring three times for each sample.

[Equation 1]

CRC (g/g) = (W _t - W ₀ ) / W ₀

W _t = Weight of SAP swollen in 0.9 wt.% NaCl aqueous solution for 30 minutes

W ₀ = weight of SAP initially injected

Absorption under pressure (AUL) measurement

A device including a macro-porous sintered glass filter plate (porosity # 0, d = 80mm, h = 7mm) was used in a self-made petri dish (d = 118mm, h = 12mm). Polymers (0.9 ± 0.01 g) according to Examples 1 and 2 and Comparative Examples 1 to 3 of the present invention were placed on a petri dish on which polyester gauze was placed, and a glass cylinder (d = 60 mm, h = 50 mm). After that, a cylindrical piston (Teflon d = 60mm) was placed on a dry SAP, and 0.9% saline was put in a petri dish while a load of 0.3 psi was applied to the SAP, and absorbed into the SAP through a glass filter. The entire equipment was sealed to prevent surface evaporation and changes in the brine concentration. Absorption Under Load (AUL) was calculated by weighing the swollen SAP after 60 minutes.

[Equation 2]

AUL (g/g) = (W1 - W0) / W0

W0 = weight of dried SAP

W1 = weight of swollen SAP

Fluid Permeability (SPT) Measurement

0.5 g of the polymers according to Examples 1 and 2 and Comparative Examples 1 to 3 of the present invention were sufficiently put in a 0.9 wt% aqueous solution of NaCl in a liquid permeability meter and swollen for 30 minutes. The time until 20ml of saline passed was measured by passing saline in a state where a load of 0.3 psi (= 106.26g) was applied to the measuring cylinder.

Biodegradability measurement

The biodegradability test method ISO 14851 test method was used to measure the decomposition degree of the material through the oxygen consumption consumed when the plastic material is decomposed using aerobic microorganisms in the water system. Scope of application of the test method Materials are linear polymers such as natural and synthetic polymers, copolymers or mixtures thereof, and the degree of decomposition of the crosslinked polymers was measured according to the characteristics.

Item Furtherance CRC
(g/g) AUL
(g/g) SPT
(sec) biodegradability
(%) Example 1 AA + IA + OS 35 20 200 95 Example 2 AA + IA + ST 33 20 250 60 Comparative Example 1 AA 37 25 120 10 Comparative Example 2 IA 30 15 600 95 Comparative Example 3 AA + IA 35 22 350 50

According to Table 1, the polymer of Comparative Example 1 in which AA was synthesized alone showed good overall physical properties, but had the lowest degree of biodegradation. In addition, the polymer of Comparative Example 2, in which IA was synthesized alone, showed a high degree of biodegradation, but other physical properties were not good.

In addition, in the case of Example 1 containing oxidized starch (OS) and Example 2 containing normal starch (ST), the degree of biodegradation of the copolymer according to Example 1 containing oxidized starch (OS) was high, Considering various physical properties and biodegradability, it was found that the copolymer (AA + IA + OS) according to Example 1 was optimal.

As mentioned above, although preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the scope of the technical spirit of the present invention. It is possible.

Claims (20)

itaconic acid;
starch;
acrylic acid derivatives; and
A polyitaconic acid graft copolymer prepared by polymerization and crosslinking a mixture comprising a crosslinking agent. According to claim 1,
The polymerization reaction includes a radical reaction and a condensation reaction,
The radical reaction is performed by radical reaction of at least one vinyl group selected from the group consisting of itaconic acid and acrylic acid derivatives,
The polyitaconic acid graft copolymer, characterized in that the condensation reaction is carried out by an esterification reaction between the hydroxyl group of the starch and at least one carboxyl group selected from the group consisting of itaconic acid and acrylic acid derivatives. 3. The method of claim 2,
The polyitaconic acid graft copolymer, characterized in that the crosslinking reaction is carried out by radical reaction of at least one vinyl group selected from the group consisting of itaconic acid and acrylic acid derivatives and the vinyl group of the crosslinking agent. According to claim 1,
The starch comprises at least one selected from the group consisting of corn starch, waxy corn starch, tapioca starch, potato starch, sweet potato starch, wheat starch, rice starch, sago starch, and modified starches thereof. graft copolymer. 5. The method of claim 4,
The modified starch is polyitaconic acid graft copolymer, characterized in that it comprises at least one selected from the group consisting of oxidized starch, acid-treated starch, ester starch, ether starch, phosphoric acid cross-linked starch, and acetyladipic acid starch . 5. The method of claim 4,
The starch is modified corn starch,
wherein the modified corn starch is selected from the group consisting of oxidized corn starch, hydroxyethylated dent corn starch, hydroxypropylated cross-linked dent corn starch, and hydroxypropylated cross-linked waxy corn starch. Poly itaconic acid graft copolymer, characterized in that it comprises more than one species. According to claim 1,
The itaconic acid is polyitaconic acid graft copolymer, characterized in that at least one compound selected from the group consisting of the following structural formulas 1 to 3.
[Structural Formula 1]

[Structural Formula 2]

[Structural Formula 3]

In Structural Formulas 1 to 3,
R ₁ and R ₂ are the same as or different from each other, and each independently represents a hydrogen atom, a C1 to C18 alkyl group, a C5 to C18 cyclic alkyl group, or a C6 to C18 aryl group,
R ₃ is each independently a valence bond, a C1 to C18 alkylene group, a C5 to C18 cyclic alkylene group, or a C6 to C18 arylene group. According to claim 1,
The acrylic acid derivative is a polyitaconic acid graft copolymer, characterized in that the compound represented by the following structural formula (4).
[Structural Formula 4]

In Structural Formula 4,
R ₄ is a hydrogen atom or a C1 to C3 alkyl group. According to claim 1,
The acrylic acid derivative is polyitaconic acid graft copolymer, characterized in that it comprises at least one selected from the group consisting of acrylic acid, methacrylic acid and methyl methacrylic acid. According to claim 1,
The polyitaconic acid graft copolymer is
at least one vinyl polymer selected from the group consisting of itaconic acid and acrylic acid derivatives;
starch grafted to the vinyl polymer;
polyitaconic acid grafted to the starch;
a polyacrylic acid derivative grafted onto the starch;
Itaconic acid-acrylic acid derivative copolymer grafted to the starch; and
Poly itaconic acid graft copolymer comprising a; a crosslinking agent for crosslinking at least one selected from the group consisting of the vinyl polymer, polyitaconic acid, polyacrylic acid derivative, and the itaconic acid-acrylic acid derivative copolymer. 11. The method of claim 10,
Poly itaconic acid graft copolymer, characterized in that the graft of the polyitaconic acid graft copolymer is by at least one selected from the group consisting of an ester bond, an ionic bond, and a hydrogen bond. According to claim 1,
The crosslinking agent is polyethylene glycol diacrylate (PEGDA), 1,6-hexanediol acrylate (HDDA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylic Rate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol di Methacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, N,N′-methylenebisacrylamide (N,N′-Methylenebisacrylamide), N,N′-ethylenebisacrylamide (N,N'-Ethylenebisacrylamide) and N,N'-propylenebisacrylamide (N,N'-Propylenebisacrylamide) polyitaconic acid graft copolymer comprising at least one selected from the group consisting of. According to claim 1,
Poly itaconic acid graft copolymer, characterized in that the poly itaconic acid graft copolymer further comprises a surface cross-linking layer. An absorbent material comprising the polyitaconic acid graft copolymer of claim 1. A method for preparing the polyitaconic acid graft copolymer of claim 1, comprising the step of polymerizing by mixing starch, itaconic acid, an acrylic acid derivative, a crosslinking agent, and an initiator. 16. The method of claim 15,
The method for preparing the polyitaconic acid graft copolymer is
(a) preparing a mixed solution containing starch, itaconic acid, an acrylic acid derivative, a crosslinking agent and a neutralizing agent; and
(b) adding an initiator to the mixed solution and reacting to prepare the polyitaconic acid graft copolymer of claim 1;
A method for producing a polyitaconic acid graft copolymer comprising a. 17. The method of claim 16,
The initiator is a peroxide, an azo compound, azobisisobutyronitrile (AIBN), persulfate, ammonium persulfate, sodium persulfate potassium persulfate, hydrogen peroxide (H ₂ O ₂ ), and tertiobutylhydroperoxide A method for producing a polyitaconic acid graft copolymer comprising at least one selected from the group consisting of. 17. The method of claim 16,
The method for producing a polyitaconic acid graft copolymer, characterized in that the neutralizing agent comprises at least one selected from the group consisting of a non-metal hydroxide, ammonium hydroxide, an organic base compound containing an alkylamine, and an organic compound containing a hydroxyl group. 17. The method of claim 16,
After step (b),
The polyitaconic acid graft copolymer, characterized in that it further comprises the step (c) of adding and reacting the polyitaconic acid graft copolymer and a surface crosslinking solution to prepare a polyitaconic acid graft copolymer having a surface crosslinking layer formed thereon. manufacturing method. 20. The method of claim 19,
The surface crosslinking solution is an alcohol compound; alkylene carbonate compounds; polyamine compounds; epoxy compounds; organic carboxylic acid compounds; polyvalent metal salts; and an inorganic compound; a method for producing a polyitaconic acid graft copolymer comprising at least one selected from the group consisting of.

Images