KR20140090959A - Biodegradable superabsorbent polymer containing tetrazole and cellulose derivatives - Google Patents

Abstract

The present invention relates to a biodegradable superabsorbent resin cross-linked and polymerized from a composition comprising a polymerizable monomer having an acryl group and a methacryl group, a tetrazole monomer, an inorganic filler, and an allyl compound of a cellulose derivative, and a method of preparing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a biodegradable superabsorbent resin comprising tetrazole and cellulose derivatives,

The present invention relates to a biodegradable water absorbent resin prepared from a composition containing a nitrogen-containing heterocyclic compound, a polymerizable monomer having an acrylic group or a methacrylic group, an inorganic filler, and an allyl compound of a cellulose derivative, and a method for producing the same.

Absorbent articles for personal hygiene, such as infant diapers, adult pads or sanitary articles for women, include an absorbent core comprising superabsorbent resin particles dispersed on a fibrous matrix. Such a superabsorbent resin generally becomes a water-swellable, water-insoluble absorber having a high absorption capacity for body fluids.

Most commonly used superabsorbent resins (SAP) for this purpose are derived from acrylic acid derived from fossil fuels such as petroleum and are known to be irreversible. That is, it is known that general acrylic acid polymers and superabsorbent resins do not exhibit biodegradability.

More specifically, the water absorbent resin may comprise at least partially neutralized polyacrylic acid, hydrolyzed starch / acrylonitrile graft copolymer, neutralized starch / acrylic acid graft copolymer, neutralized vinyl acetate / acrylic ester copolymer or hydrolyzed Acrylamide copolymers, and the like, which do not exhibit biodegradability.

However, recently interest in environmental problems has greatly increased, and interest in biodegradable absorbent polymers is increasing. Examples of previously known biodegradable and water absorbing polymers include natural polymers or mixtures of synthetic polymers with them, or graft polymers of natural polymers and synthetic polymers, and studies are actively being conducted.

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

As an example of preparing a superabsorbent polymer with such a cellulose, there is a method of reacting cellulose with a crosslinking agent having an ionic functional group to obtain a product having high biodegradability. However, this method is not economical due to its high manufacturing cost. As another example, there is a method of modifying cellulose so as to have a carboxy group, and then crosslinking the modified cellulose with a crosslinking agent. However, this method also has insufficient biodegradability of the product and can only obtain limited kinds of substances.

Furthermore, when a biodegradable water absorbing polymer is obtained by using a natural polymer in a previously known method, there is a disadvantage that it is practically difficult to apply commercially. For example, prior biodegradable polymers derived from cellulose have poorer physical properties such as water absorption and higher production costs than absorbent resins that do not exhibit biodegradability derived from fossil fuels. In addition, even when polyacrylate is grafted onto a natural polymer, it is difficult to control the degree of decomposition of the polymer, and it has disadvantages such as poor water absorption and physiological characteristics, and relatively high raw material cost.

Accordingly, there is a continuing demand for development of an absorbent resin which is derived from a natural polymer, exhibits excellent biodegradability, has an excellent water absorbing property and can be produced at a low unit cost.

The present invention provides a biodegradable absorbent resin having a crosslinked structure prepared from a composition comprising a polymerizable monomer having an acrylic group or a methacrylic group, a nitrogen-containing heterocyclic monomer, an inorganic filler, and an allyl compound of a cellulose derivative .

The present invention also provides a method for producing a biodegradable absorbent resin having a crosslinked structure by using a composition comprising a polymerizable monomer having an acrylic group or a methacrylic group, a nitrogen-containing heterocyclic monomer, an inorganic filler, and an allyl compound of a cellulose derivative To provide a method to do so.

Accordingly, the present invention relates to a method for producing a crosslinked polymer obtained from a composition comprising a polymerizable monomer having an acrylic group or a methacrylic group, a tetrazole monomer represented by the following formula (1), an inorganic filler, and an allyl compound of a cellulose derivative represented by the following formula , A biodegradable water absorbent resin and a process for producing the same.

[Chemical Formula 1]

And wherein, R ¹ is independently a polymerizable or cross-linked C ₁ -C ₁₀ hydrocarbon group having an unsaturated group,

R ² is hydrogen, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkenyl group, or a C ₁ -C ₆ halogenated alkyl group having a halogen of F, Cl, Br or I,

(2)

Wherein each R ³ is independently selected from the group consisting of hydrogen, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkenyl group, a C ₂ -C ₆ alkylcarboxy group, a C ₂ -C ₆ alkanoyl group, or F, Cl, Br Or a C ₁ -C ₆ halogenated alkyl group having a halogen of I, and n is an integer from 5 to 100.

The tetrazole monomer is a kind of nitrogen-containing heterocyclo compound, which can further improve water absorption of the cross-linked water-absorbent resin. Such tetrazole monomers may have the structure of the above formula (1). In a more suitable example, R ¹ in Formula 1 is independently a vinyl group or an allyl group, and R ² may independently be hydrogen or a methyl group. More specifically, the tetrazole monomer may be 5-vinyl tetrazole or 2-methyl-5-vinyl tetrazole.

Such tetrazole monomers may be included in an amount of 3 to 16% by weight, based on 100% by weight of the total solids content of the composition. If the content of the tetrazole monomer is excessively low, the biodegradation rate and absorption rate of the water absorbent resin may be insufficient. On the other hand, if the content thereof is excessively high, the polymerization rate for producing the water absorbent resin may be lowered, and the conversion to the resin and the yield may be lowered.

The polymerizable monomer having an acrylic group or a methacrylic group may be any acrylic or methacrylic monomer having an unsaturated double bond polymerizable by radical polymerization. Suitably such polymerizable monomers may be any monomers that can be polymerized by free-radical polymerization.

Specific examples of such monomers include an acrylate-based compound having a polymerizable (meth) acryl group or a derivative thereof, a methacrylate-based compound or a derivative thereof, acrylic acid or a derivative thereof, or methacrylic acid or a derivative thereof.

The monomer may be included in an amount of 30 to 50% by weight based on 100% by weight of the total solid content of the composition. Thereby, the conversion ratio to the water absorbent resin can be sufficient.

The allyl compound of the cellulose derivative means that the terminal functional group of the cellulose derivative is an allyl group. Examples of the cellulose derivative include cellulose nitrate (CN) substituted with a hydroxyl group present in a cellulose repeating unit by acetylation or esterification, Cellulose acetate (CA), methylcellulose (MC), dimethylcellulose, triacetylcellulose or ethylcellulose (EC). A suitable example of the cellulose derivative may be a compound represented by the general formula (2). In a more suitable example, R ³ in Formula 2 may independently be hydrogen, a C ₂ -C ₆ alkylcarboxy group, or a C ₂ -C ₆ alkanoyl group.

The allyl compound of the cellulose derivative may be contained in an amount of 2 to 10.0% by weight based on 100% by weight of the total solid content of the composition. If these components are included in an excessively high content, the water absorbent resin may exhibit an uncontrolled decomposition rate.

As the inorganic filler, clay minerals such as bentonite, montmorillonite, zeolite or kaolin may be used. Since such clay minerals have a layered structure and can exhibit excellent water absorbency, the above-mentioned water absorbent resin molded article can contribute to easy decomposition and excellent absorbability. More suitably, bentonite can be used as the inorganic filler.

The inorganic filler may be used either as a particulate or as an active liquid. For example, a bentonite suspension can be easily obtained by adding bentonite to water and stirring, and suspension or particulates of other inorganic fillers can also be obtained by a conventional method.

The inorganic filler may be contained in an amount of 0.01 to 10% by weight based on 100% by weight of the total solid content of the composition. If such a component is included in an excessively low content, the effect as a nanoscale fine additive may not be sufficiently manifested. On the contrary, if the component is contained in an excessively high content, the water absorbency of the water absorbent resin may be deteriorated.

In a suitable example, the polymerization for producing the water absorbent resin may be carried out by radical or thermal polymerization, in which various initiators, for example, redox initiators, etc., may be used.

In the polymerization process, the amine containing compound may act as a reducing agent in the redox pair initiator system, and an oxidizing agent may be used in conjunction with such amine containing compound to achieve a full initiator system.

Suitable oxidizing agents include potasium persulfate, ammonium persulfate, sodium persulfate, or other alkali metal persulfates. Examples of the amine-containing compound that can be suitably used include allyl amines, diamines, triamines, alkoxyamines, ammonium, and iminium salts. More specific examples include diallylamine-based compounds, 2- (dimethyamino) ethyl methacrylate; Ethylenediamine-based compounds such as tetraethylenediamine and tetramethylenediamine; Propylene diamine compounds such as N, N, N ', N' - (3-pentamethylene) diamine; Triamine or tetraamine compounds such as N, N, N ', N', N'-pentamethyldiethylenediamine or hexamethylenetetraamine; or ammonium or iminium salts such as tetrabutylammonium chloride or dimethylmethyleneammonium chloride And the like.

Suitable examples of initiator systems may be persulfate compounds and amine compounds, more suitably ammonium persulfate and tetramethylenediamine (TMED). The persulfate compound and the amine compound in the initiator system can be mixed in a weight ratio of 2: 1 to 1: 2.

The content of each component in the initiator system may be from 0.5 to 5 wt%, or from 1 to 2 wt%, based on 100 wt% of the total solids content of the composition.

By using the initiator system, the polymerization temperature can be lowered, and the use of suitable initiator systems is of substantial importance. If the content of the amine compound such as TMED is out of the above range of the mixing weight or content, the strength and the like of the final product may be lowered and the hardness in the swollen state may not be sufficient.

 On the other hand, in the above-described method for producing an absorbent resin, the above-mentioned composition can be subjected to radical polymerization in an aqueous medium, and such polymerization can be carried out at 20 to 70 ° C for 2 to 4 hours. At this time, an ammonium persulfate-TMED redox initiator system may be used, wherein the persulfate and TMED in such an initiator system may be mixed in a molar ratio of 1: 0.5 to 1: 2.

Thus, a biodegradable water absorbent resin having a crosslinked structure can be suitably produced.

INDUSTRIAL APPLICABILITY The present invention relates to a water absorbent resin which exhibits biodegradability by the use of an allyl compound and a tetrazole comonomer of a cellulose derivative without deteriorating the main physical properties including absorbency in comparison with conventional superabsorbent resins based on poly (acrylic acid) Can be manufactured and provided. The present invention relating to such a water absorbent resin does not cause problems such as difficulty in securing the physical properties of a natural polymer-based method and low marketability due to a high production cost, and it is difficult to accumulate poly (acrylic acid) based superabsorbent resin It is easy to apply various techniques.

Figure 1 shows the dependence of gelation on the synthesis of biodegradable water absorbent resins, depending on the content of 2-methyl-5-vinyltetrazole.
Fig. 2 shows the results of the biodegradability test conducted in Test Example 2. Fig.

The following examples illustrate the invention in order to facilitate understanding of the invention. However, the scope of the invention is not limited to the following examples.

Example 1

In the first step, allyl-carboxymethylcellulose crosslinker (ACMC) was synthesized.

First, the CMC was weighed and added to a flask with stirrer, reflux condenser and funnel. Isopropyl alcohol (M = 1:30) was added to the flask and then heated to 50 占 폚. After 1 hour, 1 mole of sodium hydroxide was added to the flask and stirred at 50 占 폚 for 1 hour. The allyl bromide was then added to the flask and stirred at 50 < 0 > C for 1 hour. The reaction mixture containing ACMC was distilled to remove isopropyl alcohol and dried at 40 占 폚 for one day to finally obtain 10 g of ACMC powder.

Next, 0.8 g (0.005 mol) of 14M NaOH was added to 2.1 g (0.029 mol) of acrylic acid to partially neutralize the acrylic acid with sodium hydroxide to obtain 1.25 g of partially neutralized acrylic acid (alpha = 0.8) . Then, 0.02 g of TMED and 2-methyl-5-vinyltetrazole were added to the flask and thoroughly mixed using an ultrasonic disperser for 10 to 15 minutes. Further, other necessary components were added to prepare a composition for radical polymerization in which the content (wt.%) In the solids content of the partially neutralized acrylic acid, bentonite, ACMC, 2-methyl-vinyltetrazole (MVT) .

In the polymerization step, 0.02 g of ammonium persulfate (1 wt%) was added to the flask and maintained at a temperature of 40 +/- 2 DEG C to complete the polymerization. The final product was dried in an oven at 40 < 0 > C.

Examples 2 to 4

The water absorbent resins of Examples 2 to 4 were prepared in the same manner as in Example 1, except that the polymerization was carried out using the modified compositions shown in Table 1 below.

The amount (content) of each component in the composition for polymerization Acrylic acid (g) ACMC (g) MVT (g) Bentonite (g) Example 1 2.1 0.05 (2% by weight) 0.1 (4% by weight) 0.1 (4% by weight) Example 2 2.1 0.05 (2% by weight) 0.2 (8% by weight) 0.1 (4% by weight) Example 3 2.1 0.05 (2% by weight) 0.3 (12% by weight) 0.1 (4% by weight) Example 4 2.1 0.05 (2% by weight) 0.4 (16% by weight) 0.1 (4% by weight)

Test Example 1: Evaluation of gelation time and absorbency

(1) Gelation time

A study on the gelation initiation time of the water absorbent resin of the examples according to the MVT concentration was conducted. The experimental results are shown in Fig.

One of the greatest features of the polymer network formation is the gelling initiation time, which does not mean the polymerization initiation time, but is understood to actually start immediately upon introduction of the initiator. Since the viscosity of the reaction composition increased as the polymerization proceeded, the gelling initiation time decreased as the monomer content in the composition increased. Therefore, in addition to the basic factors of synthesis such as the concentrations of crosslinking agent, initiator and inorganic filler, and reaction temperature, it was necessary to study the influence of specific parameters on the gel initiation time. The dependence of the gelation initiation time of the biodegradable composition on the content of 2-methyl-5-vinyltetrazole is shown in Fig.

As shown in Fig. 1, in the composition for preparing a biodegradable water absorbent resin, the gelation initiation time decreases as the content of 2-methyl-5-vinyltetrazole increases. This is probably due to the activity of MVT May be due to an increase in the terminal double bond.

(2) Absorbency

The water absorbency of the water absorbent resin having the crosslinked structure obtained in the examples was measured in distilled water and physiological saline.

The specific absorbability test method was as follows.

1 g of the sample was placed in a glass container containing 250 mL of distilled water or physiological saline. The swelling time was 1 to 3 days for physiological saline and 2 days for distilled water. The temperature was 18 deg. The equilibrium swelling value was calculated using the following equation.

Q = (MSP / MDP)

Where Q is the equilibrium expansion (g / g), MSP is the weight (g) of the expanded resin, and MDP is the weight (g) of the dry resin.

The results of the measurement of the absorbency are shown in Table 2 below.

MVT (g) Absorbency (g / g) for distilled water Absorbency against physiological saline (g / g) Example 1 0.1 (4% by weight) 180 40 Example 2 0.2 (8% by weight) 165 70 Example 3 0.3 (12% by weight) 270 60 Example 4 0.4 (16% by weight) 110 30

Referring to Table 2, the maximum equilibrium swelling of the water absorbent resin is 270 g / g in the case of distilled water and 70 g / g in the case of Example 2 in saline.

Example 5: Water absorbent resin production for biodegradability evaluation

Absorbent resins of samples 1 to 4 for biodegradability evaluation were prepared in the same manner as in Example 1, except that the polymerization was carried out using the modified compositions shown in Table 3 below.

Sample composition and composition Acrylic acid (g) ACMC (g) MVT (g) Bentonite (g) Sample 1 2 0.2 0 0 Sample 2 2 0.2 0 0.1 Sample 3 2 0.2 0.4 0 Sample 4 2 0.2 0.4 0.1 Cottonseed cellulose

Test Example 2: Evaluation of biodegradability

The biodegradability of the water absorbent resin was evaluated according to the method described in Hao Feng, Jian Li and Lijuan Wang, "Preparation of biodegradable flax shade cellulose-based superabsorbent polymer under microwave irradiation, Bioresources 5 (3) p. The biodegradability of the water absorbent resin of Example 5 was evaluated at 40 DEG C over two weeks, and the evaluation result was compared with cotton wool.

These resin samples were placed in a nylon container and maintained at a depth of 10 cm with the soil in the box. The box was placed in the presence of humidity at 40 ° C. The weight of each sample was measured every two days, and such weighing was stopped as the resin became miscible with the container. In the case of samples 1 to 4 in the final state, it was resolved that it was no longer detachable from the container.

These experimental results are shown in Fig. Referring to FIG. 2, it was confirmed that the weight of the resin sample significantly decreased with time, indicating biodegradability. However, in the beginning, it can be confirmed that the weight of the resin sample is partially increased due to the influence of moisture in the air.

Claims (11)

Crosslinked polymer obtained from a composition comprising a polymerizable monomer having an acrylic group or a methacrylic group, a tetrazole monomer represented by the following formula (1), an inorganic filler and an allyl compound of a cellulose derivative represented by the following formula (2) Suzy:
[Chemical Formula 1]

And wherein, R ¹ is independently a polymerizable or cross-linked C ₁ -C ₁₀ hydrocarbon group having an unsaturated group,
R ² is hydrogen, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkenyl group, or a C ₁ -C ₆ halogenated alkyl group having a halogen of F, Cl, Br or I,
(2)

Wherein each R ³ is independently selected from the group consisting of hydrogen, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkenyl group, a C ₂ -C ₆ alkylcarboxy group, a C ₂ -C ₆ alkanoyl group, or F, Cl, Br Or a C ₁ -C ₆ halogenated alkyl group having a halogen of I, and n is an integer from 5 to 100.
The method of claim 1, wherein, R ¹ is a vinyl group or an allyl group independently, R ² are independently hydrogen or a methyl group in the biodegradable water absorbent resin in the above formula (1).
The biodegradable water absorbent resin according to claim 1, wherein the tetrazole monomer is 5-vinyl tetrazole or 2-methyl-5-vinyl tetrazole.
The biodegradable absorbent polymer of claim 1, wherein R ³ is independently hydrogen, a C ₂ -C ₆ alkylcarboxy group, or a C ₂ -C ₆ alkanoyl group.
The biodegradable absorbent resin according to claim 4, wherein the allyl compound of the cellulose derivative is an allyl compound of carboxymethylcellulose, methylcellulose, dimethylcellulose or triacetylcellulose.
The biodegradable absorbent resin according to claim 1, wherein the inorganic filler is selected from the group consisting of bentonite, montmorillonite, zeolite and kaolin.
The biodegradable absorbent resin according to claim 1, wherein the polymerizable monomer having an acrylic group or a methacrylic group is acrylic acid or methacrylic acid.
The composition of claim 1 wherein said composition comprises 30 to 50 wt% of said polymerizable monomer, 3 to 16 wt% of said tetrazole monomer, 0.01 to 10 wt% of said inorganic filler, % Of the allyl compound and 2 to 10.0% by weight of the allyl compound.
Comprising crosslinking a composition comprising a polymerizable monomer having an acrylic group or a methacrylic group, a tetrazole monomer represented by the following formula (1), an inorganic filler, and an allyl compound of a cellulose derivative represented by the following formula (2) Method of producing polymerized, biodegradable absorbent resin:
[Chemical Formula 1]

And wherein, R ¹ is independently a polymerizable or cross-linked C ₁ -C ₁₀ hydrocarbon group having an unsaturated group,
R ² is hydrogen, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkenyl group, or a C ₁ -C ₆ halogenated alkyl group having a halogen of F, Cl, Br or I,
(2)

Wherein each R ³ is independently selected from the group consisting of hydrogen, a C ₁ -C ₆ alkyl group, a C ₁ -C ₆ alkenyl group, a C ₂ -C ₆ alkylcarboxy group, a C ₂ -C ₆ alkanoyl group, or F, Cl, Br Or a C ₁ -C ₆ halogenated alkyl group having a halogen of I, and n is an integer from 5 to 100.
The method of producing a biodegradable water absorbent resin according to claim 9, wherein the inorganic filler is added in particulate form or in the form of an active liquid.
The method of producing a biodegradable water absorbent resin according to claim 9, wherein the polymerization step proceeds by radical polymerization.

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