WO2018199725A2 - Method for preparing citraconic acid-containing super absorbent polymer using silver nitrate aqueous solution and antibacterial super absorbent polymer prepared thereby - Google Patents

Abstract

The present invention relates to a method for preparing an antibacterial super absorbent polymer by adding a silver nitrate aqueous solution to a solution containing citraconic acid (CCA) and vinylpyrrolidone (VP) as monomers, followed by UV irradiation, to an antibacterial super absorbent polymer prepared by the method, the antibacterial super absorbent polymer having an increased content of nano silver ions, and to a hygiene product manufactured from the antibacterial super absorbent polymer.

Description

Method for preparing citraconic acid-containing superabsorbent polymer using silver nitrate solution and superabsorbent polymer having antibacterial effect

The present invention provides a method for producing a superabsorbent polymer having antimicrobial activity, wherein an aqueous solution of silver nitrate is added to a solution containing citraconic acid (CCA) and vinylpyrrolidinone (VP) as a monomer and irradiated with ultraviolet rays. The present invention relates to a super absorbent polymer having an increased antimicrobial content and a sanitary article prepared therefrom.

Generally, superabsorbent polymers are materials capable of absorbing and retaining water of about 500 to 1,000 times its own weight, and crosslinked polymers are generally used. These superabsorbent polymers are used as agricultural, horticultural soil repair agents, seedling sheets, packaging materials for food distribution, and the like, and demand for diapers for infants, adults, and animals is increasing rapidly.

As such, while the superabsorbent polymer is used as a material that directly or indirectly contacts the human body, such as food packaging materials and diapers, research for imparting antimicrobial properties to materials has been in the spotlight. As part of this effort, the resin was prepared using an antimicrobial monomer, and when the resin thus prepared is used in a diaper or a sanitary napkin, there is an advantage of reducing odor caused by bacteria.

Charlotte James of Bath University of England et al. Prepared a superabsorbent polymer using polyacrylic acid and an antimicrobial crosslinking agent incorporating zinc ions in order to increase the antimicrobial properties of the superabsorbent polymer. In addition, Ching Ting Tsao et al. Of the National Taiwan University produced a PGA-chitosan hydrogel, a hydrogel formed by crosslinking by ion bonding, and reported that the hydrogel exhibited antimicrobial activity against Escherichia coli. As mentioned above, research for improving the antimicrobial activity of a crosslinked polymer is actively going on.

On the other hand, the super absorbent polymers currently used in products close to the human body are suitable for absorbing performance such as pressure absorbing ability and water holding ability, but have a disadvantage of inferior antimicrobial properties. The superabsorbent polymer has different absorbency under certain conditions such as absorption rate, water holding capacity and pressure depending on the type of monomer, crosslinking agent and clay mineral used in the preparation thereof, and post-treatment process. Accordingly, in the case of the crosslinked polymer prepared to have appropriate antimicrobial properties, it may not have the absorption capacity required in the industrial field, or only a small amount of a material such as a crosslinking agent may have antimicrobial properties. For example, it is difficult to find a material having appropriate antimicrobial properties while maintaining excellent absorbency.

The present inventors have diligently researched to find a simple and economical method for preparing a superabsorbent polymer having excellent antimicrobial activity while maintaining high absorption ability. As a result, the inventors used citraconic acid and vinylpyrrolidinone as monomers for crosslinking. To prepare a hydrogel, but by adding a silver nitrate solution to the solution mixed with a cross-linking agent and a photoinitiator to the monomer, it was confirmed that the water-absorbing performance can be improved as well as to prepare a resin having antibacterial, and completed the present invention.

One object of the present invention is a first step of adding and mixing vinylpyrrolidinone (VP) and a crosslinking agent to a solution containing partially or completely neutralized citraconic acid (CCA); A second step of adding and mixing an aqueous solution of silver nitrate to the solution obtained from the first step; A third step of adding and mixing a photoinitiator and ammonium persulfate to the solution obtained from the second step; And a fourth step of pouring the solution obtained from the third step into a mold and irradiating ultraviolet rays.

Another object of the present invention is to provide a superabsorbent polymer having antimicrobial properties containing silver nanoions and citraconic acid.

Still another object of the present invention is to provide a sanitary article made of a super absorbent polymer having the antibacterial property.

In the method of the present invention, a solution containing citraconic acid and vinylpyrrolidinone as a monomer is added with an aqueous solution of silver nitrate as a silver precursor and irradiated with ultraviolet rays to form a hydrogel by crosslinking reaction, and at the same time, silver nanoions are formed therein. By being formed, it is possible to provide a superabsorbent polymer containing silver nanoions in a higher content. In particular, the production method of the present invention can be carried out through a simple and economical process of simply adding an aqueous solution of silver nitrate, and the resin produced therefrom exhibits excellent antibacterial properties and maintains its unique properties, high absorption, and therefore, It can be usefully used for contacting diapers or women's sanitary products.

1 is a diagram showing the results of ICP-MS measurement over time of a super absorbent polymer prepared by adding a silver nitrate aqueous solution and silver nanoparticles.

As one embodiment for achieving the above object, the present invention is to add a mixture of vinylpyrrolidinone (VP) and a crosslinking agent to a solution containing partially or completely neutralized citraconic acid (CCA) First step; A second step of adding and mixing an aqueous solution of silver nitrate to the solution obtained from the first step; A third step of adding and mixing a photoinitiator and ammonium persulfate to the solution obtained from the second step; And a fourth step of pouring the solution obtained from the third step into a mold and irradiating ultraviolet rays.

The present invention provides a resin having a high absorption capacity by irradiating UV-crosslinked solution containing citraconic acid and vinylpyrrolidinone, but when silver nitrate aqueous solution is added to the solution is crosslinked by UV irradiation and at the same time silver nano Since ions are formed, it is possible to provide an antimicrobial and superabsorbent resin that maintains a high absorbing capacity of the resin itself while exhibiting significantly increased antimicrobial properties including silver nanoions in a uniform and much higher content than adding preformed silver nanoparticles. Based on finding

In the manufacturing method of the present invention, the first step is to add a vinylpyrrolidinone and a crosslinking agent to a solution containing citraconic acid at the same time, or to mix, or to add a vinylpyrrolidinone first and then to add a crosslinking agent It may be mixed, but is not limited thereto.

For example, in the production method of the present invention, in the first step, vinylpyrrolidinone may be added in a molar ratio of 2: 8 to 8: 2 relative to citraconic acid. Specifically, citraconic acid and vinylpyrrolidinone may be mixed in a molar ratio of 4: 6 to 8: 2, 3: 7 to 7: 3, or 4: 6 to 6: 4, but are not limited thereto. However, when the molar ratio of citraconic acid to vinylpyrrolidinone to be used is less than 2: 8, it may be difficult to exhibit the desired degree of antimicrobial activity. On the other hand, when the molar ratio of citraconic acid to vinyl pyrrolidinone to be used is greater than 8: 2, the adsorption of silver nano ions becomes disadvantageous due to the relatively low content of vinylpyrrolidinone, and thus the silver contained in the resin It may be difficult to achieve the desired degree of antimicrobial activity as the content of nano ions decreases, thereby lowering the antimicrobial improvement rate.

For example, in the manufacturing method of the present invention, the crosslinking agent may be a material having a functional group in the sock end so as to crosslink through the vinyl group of the citraconic acid and vinylpyrrolidinone which is a monomer having a vinyl group when UV irradiation. For example, as the crosslinking agent, polyethylene glycol diacrylate (PEGDA) having a reactive acrylate group in the sock end of polyethylene glycol may be used, but is not limited thereto, and is known by ultraviolet irradiation known in the art. The material used as a crosslinking agent in the preparation of the superabsorbent polymer to be formed can be used without limitation.

At this time, in the manufacturing method of the present invention, the crosslinking agent in the first step may be added in an amount of 0.3 to 1.7wt% based on the solution containing citraconic acid and vinylpyrrolidinone. Specifically, the crosslinking agent may be added in an amount of 0.5 to 1.5 wt% based on the solution obtained from the first step, but is not limited thereto. However, when the content of the crosslinking agent is less than 0.3wt%, the water-retaining capacity is increased but the pressure-absorbing capacity is decreased, and thus it may be difficult to achieve a desired level.In contrast, when the content of the crosslinking agent is more than 1.7wt%, the water-absorbing capacity is increased, but the water-retaining capacity is increased. This decrease can be difficult to achieve the desired level. That is, when the cross-linking agent is added in an amount outside the above range, it may be difficult to provide a resin having a desired water absorption performance, that is, a water holding capacity and a pressure absorbing capacity combined in a desired range.

For example, in the manufacturing method of the present invention, the silver nitrate in the third step may be added in a ratio of 0.1 to 1.5 mol% relative to the total moles of citraconic acid and vinylpyrrolidinone. Specifically, it may be added in a ratio of 0.2 to 1.2 mol% or 0.3 to 1 mol% with respect to the total moles of citraconic acid and vinylpyrrolidinone, but is not limited thereto. However, when the amount of nitric acid is less than 0.1 mol% based on the total moles of citraconic acid and vinylpyrrolidinone, it may be difficult to achieve a desired level of antimicrobial activity. On the other hand, when the amount of the nitric acid used is more than 1.5 mol% based on the total moles of citraconic acid and vinylpyrrolidinone, the synthesis of the resin itself is difficult due to the excessive generation of silver nanoions, which may lower the absorption performance.

In a specific embodiment of the present invention, 5-15 mmol of silver nitrate is added to a solution containing 0.8 mol of citraconic acid and vinylpyrrolidinone, that is, a total of 1.6 mol of citraconic acid or vinylpyrrolidinone. I was.

For example, the photoinitiator is 2-hydroxy-2-methylpropiophenone, and 2-hydroxy-4 '-(2-hydroxyethoxy) -2-methylpropiope. Alpha hydroxy ketone compounds such as non- (2-hydroxy-4 '-(2-hydroxyethoxy) -2-methylpropiophenone) can be used. Specifically, Irgacure 1173 or Irgacure 2959, which are commercially available and commercially available based on the alpha hydroxy ketone, may be used, but is not limited thereto.

For example, the production method of the present invention may further comprise a sixth step of drying the product obtained from the fifth step at 40 to 100 ℃ for 6 to 48 hours. Specifically, the sixth step may be performed at 50 to 70 ℃, but is not limited thereto. If the drying temperature is less than 40 ℃ may require a long time for drying, or incomplete drying can be made, if it exceeds 100 ℃ may deteriorate the performance by modifying the structure of the super absorbent polymer. In addition, the sixth step may be performed for 12 to 36 hours, but is not limited thereto. Through the additional drying step it is possible to further improve the absorption performance of the superabsorbent polymer of the present invention.

Due to the nature of the polymer, it may be accompanied by structural modification over high temperature and / or time, and in the super absorbent polymer, such structural modification may cause a decrease in absorption performance. On the other hand, the citraconic acid used in the superabsorbent polymer of the present invention has a somewhat lower heat resistance than the acrylic acid used in the conventional superabsorbent resin, so it is important to select a temperature that is not too high so that structural modification does not occur in the drying step. As described above, the drying time may also be another factor of denaturation, and the drying time and temperature may be selected in a mutually complementary combination so as not to cause structural modification of the prepared superabsorbent polymer.

In another aspect, the present invention provides a superabsorbent polymer having antimicrobial properties containing silver nanoions and citraconic acid. The super absorbent polymer having the antimicrobial property may be prepared by the method of the present invention, but is not limited thereto.

As used herein, the term "silver nanoion" may refer to charged particles having a size of nanoscale.

For example, the super absorbent polymer of the present invention may exhibit antimicrobial activity against E. coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella. Specifically, the super absorbent polymer of the present invention may exhibit antimicrobial activity against E. coli, but is not limited thereto.

As another aspect, the present invention provides a sanitary article made of a super absorbent polymer having the antimicrobial properties.

In this case, the super absorbent polymer may be used in the form of particles of several hundred micrometers in size, for example, 200 to 600 micrometers in size, but is not limited thereto.

Specifically, the hygiene article made of the superabsorbent polymer having the antimicrobial properties of the present invention may be a baby diaper, an adult diaper or a women's physiological article in direct contact with the human body. In addition, it may be used as a food packaging material or an agricultural soil repair agent that may indirectly affect the human body, but is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention more specifically, but the scope of the present invention is not limited by these examples.

Example  1: antimicrobial activity using silver nitrate Citraconic acid  Preparation of Containing Super Absorbent Resin

Citraconic acid (CCA), 1-vinyl-2-pyrrolidinone (VP), polyethylene glycol diacrylate (PEGDA) and silver nitrate (AgNO ₃ ) Using this, the antimicrobial superabsorbent resin which is a silver containing CCA-VP-PEGDA crosslinking copolymer was manufactured.

Specifically, 0.8 mol of CCA was added to a 500 mL flask and neutralized using 50 wt% caustic soda solution. After stirring sufficiently, 0.8 mole of VP was added followed by 1 wt% PEGDA. After sufficient dissolution of the mixed solution, 10 mmol of silver nitrate aqueous solution was added. After the mixture was sufficiently mixed, Irgacure 1173 and ammonium persulfate were added as a photoinitiator and mixed. The resulting mixture was poured into a wide flat flask and covered with flat glass and irradiated with UV at 254 nm wavelength for 90 minutes. At this time, the distance between the UV lamp and the mixed solution was maintained at 1 cm. The crosslinked sample was carefully taken out and dried in a 60 ° C. oven for 24 hours.

Example 2 Preparation of Silver Nitrate-Containing Superabsorbent Resin with Citraconic Acid Content Modified 1

Superabsorbent polymer was prepared in the same manner as in Example 1, except that CCA and VP were used in a molar ratio of 5: 5 to 3: 7.

Example 3 Preparation of Silver Nitrate-Containing Superabsorbent Resin with Citraconic Acid Content Modified 2

Superabsorbent polymer was prepared in the same manner as in Example 1, except that CCA and VP were used in a molar ratio of 5: 5 to 7: 3.

Example 4 Preparation of Super Absorbent Polymer with Controlled Silver Nitrate Content

A super absorbent polymer was prepared in the same manner as in Example 1, except that the amount of silver nitrate was reduced from 10 mmol to 5 mmol.

Example 5 Preparation of Super Absorbent Polymers with Controlled Silver Nitrate Content 2

Super absorbent polymer was prepared in the same manner as in Example 1, except that the amount of silver nitrate was increased from 10 mmol to 15 mmol.

Example 6 Preparation of Silver Nitrate-Containing Superabsorbent Polymers with Controlled Crosslinker Content 1

Superabsorbent polymer was prepared in the same manner as in Example 1, except that the amount of the crosslinking agent was reduced from 1% by weight to 0.5% by weight.

Example 7 Preparation of Silver Nitrate-Containing Superabsorbent Polymers with Controlled Crosslinker Content 2

Superabsorbent polymer was prepared in the same manner as in Example 1, except that the amount of the crosslinking agent was increased from 1 wt% to 1.5 wt%.

Comparative example  1: antimicrobial activity using silver nanoparticles Citraconic acid  Preparation of Containing Super Absorbent Resin

Superabsorbent polymer was prepared in the same manner as in Example 1, except that silver nanoparticles were added instead of the silver nitrate solution.

Comparative Example 2: Preparation of Citraconic Acid-Containing Superabsorbent Resin Without Antibacterial Substance

Superabsorbent polymer was prepared in the same manner as in Example 1, except that the aqueous solution of nitric acid was not included.

Comparative example  3: Citraconic acid  Preparation of superabsorbent polymers, including but not limited to silver silver nitrate

Superabsorbent polymer was prepared in the same manner as in Example 1, except that only VP was used instead of CCA.

Experimental Example 1 Measurement of Absorption Performance of Super Absorbent Polymer

	Monomer (molar ratio)	Crosslinking agent (content)	Antimicrobial substance (content)
Example 1	CCA / VP (5: 5)	PEGDA (1 wt%)	AgNO 3 (10 mmol)
Example 2	CCA / VP (3: 7)	PEGDA (1 wt%)	AgNO 3 (10 mmol)
Example 3	CCA / VP (7: 3)	PEGDA (1 wt%)	AgNO 3 (10 mmol)
Example 4	CCA / VP (5: 5)	PEGDA (1 wt%)	AgNO 3 (5 mmol)
Example 5	CCA / VP (5: 5)	PEGDA (1 wt%)	AgNO 3 (15 mmol)
Example 6	CCA / VP (5: 5)	PEGDA (0.5 wt%)	AgNO 3 (10 mmol)
Example 7	CCA / VP (5: 5)	PEGDA (1.5 wt%)	AgNO 3 (10 mmol)
Comparative Example 1	CCA / VP (5: 5)	PEGDA (1 wt%)	Silver nanoparticles
Comparative Example 2	CCA / VP (5: 5)	PEGDA (1 wt%)	-
Comparative Example 3	CCA / VP (0:10)	PEGDA (1 wt%)	AgNO 3 (10 mmol)

The absorbency of the superabsorbent polymers of Examples 1 to 7 and Comparative Examples 1 to 3 prepared in the amounts shown in Table 1, that is, water-retaining capacity, pressure-absorbing capacity, and liquid permeability, were measured as follows, and the results are shown in Table 2 below. Together.

1-1. Water retention measurement

0.2 g of superabsorbent resin was fully swollen in 0.9% saline for 30 minutes, and then centrifuged at 300 gf to remove the separated saline and the amount of swelling was measured. From this the water capacity was calculated using the following formula:

Wherein W ₁ is the weight of the swollen superabsorbent resin and W ₀ is the weight of the dried superabsorbent polymer.

1-2. Pressurized absorption capacity measurement

Superabsorbent polymers were fabricated using equipment containing macroporous glass filter plates (porosity # 0, d = 80 mm, h = 7 mm) sintered in a self-made petri dish (d = 118 mm, h = 12 mm). Pressurized absorption capacity was measured.

Specifically, 0.4 g of the dried superabsorbent resin was placed on a petri dish in which polyester gauze was placed, and the periphery of the superabsorbent resin was closed with a glass cylinder (d = 60 mm, h = 50 mm). Cylindrical pistons (Teflon d = 60 mm) were placed on the dry superabsorbent resin, and 0.9% saline was added to the Petri dish with a load of 0.3 psi and absorbed into the superabsorbent resin through the glass filter. The entire instrument was sealed to prevent surface evaporation and brine concentration changes. After 60 minutes the weight of the swollen particles was measured and the Absorption Under Load (AUL) was calculated using the following equation:

Wherein W ₁ is the weight of the dried superabsorbent polymer and W ₂ is the weight of the swollen superabsorbent polymer.

1-3. Liquidity measurement

After fully swelling 0.5 g of superabsorbent polymer in 100 mL of 0.9% brine, the swollen superabsorbent resin was separated and passed through 20 mL of 0.9% brine. At this time, the time taken for the 20 mL of brine to be passed completely through the super absorbent polymer was measured by liquid permeability.

	Water retention capacity (g / g)	Pressurized Absorption Capacity (g / g)	Fluidity (sec)
Example 1	35.2	14.7	280
Example 2	33.7	12.6	293
Example 3	33.4	12.9	289
Example 4	31.2	12.1	294
Example 5	33.4	12.7	299
Example 6	36.5	12.7	282
Example 7	31.8	16.1	275
Comparative Example 1	27.3	12.5	301
Comparative Example 2	31.1	13.5	313
Comparative Example 3	23.1	11.3	327

As shown in Table 2, the highest absorption performance for the super absorbent polymer of Example 1 was measured. When the results for Example 1 were compared with the results for the resin of Comparative Example 2, which is a silver-free comparison group, water retention and pressure absorption capacity were increased, which is the internal structure of the resin due to the silver nanoions contained in the resin. It has been shown that the expansion of increases the water holding capacity and the increase in the strength of the gel due to the inclusion of the silver nanoions contributes to the improvement of the pressure absorption capacity.

In addition, the resin of Example 1 prepared by adding a silver nitrate aqueous solution to the monomer mixture solution was compared with the results of the resin of Comparative Example 1 prepared by containing the silver nanoparticles prepared in advance in both the water holding capacity and the pressure absorption capacity. It was shown to have excellent absorption performance compared to the resin of Example 1. It is considered that this is because the absorption capacity due to osmotic pressure is improved by increasing the concentration of ions in the superabsorbent polymer when the aqueous solution of silver nitrate is used.

Compared with Example 1, the results for Examples 2 and 3 in which the ratio of citraconic acid to vinylpyrrolidinone was increased or decreased, it was found that both have better absorption performance than Comparative Examples 1 to 3, There was a tendency to decrease somewhat compared to Example 1. This is presumably because when the comonomer is used in a ratio outside of a certain range, a homopolymer of a monomer present in excess in addition to the copolymer having a desired structure is additionally formed and incorporated.

On the other hand, compared with Example 1, the results for Examples 4 and 5 in which the amount of silver nitrate increased or decreased, it was shown that all have better absorption performance than Comparative Examples 1 to 3, compared to Example 1 There was a tendency to decrease somewhat. This means that as the content of silver nitrate increases, the ion content and gel strength in the superabsorbent resin increase, so that the water-retaining capacity and the pressure-absorbing capacity can be improved at the same time. It indicates that it may be a factor that inhibits the synthesis of the polymer resin by crosslinking.

In addition, by comparing the results for the resins of Examples 1 and 7 prepared by adjusting the amount of silver nitrate from Example 1, it was confirmed that the antimicrobial activity is improved as the amount of silver nitrate increases.

Experimental Example 3: Determination of antimicrobial persistence of superabsorbent polymer

In order to confirm the change in the content of silver nanoions contained in the resin over time, ICP-MS of the superabsorbent polymers prepared according to Example 1 and Comparative Example 1 of the present invention was prepared for 9 days at an interval of 1 day immediately after preparation. It measured until, and the result is shown in FIG.

As shown in FIG. 1, when comparing the resins of Example 1 and Comparative Example 1 prepared in the same manner except for using silver aqueous solution and silver nanoparticles, respectively, the resin of Example 1 was immediately prepared as well as 9 Even after days passed, the silver nano ions were contained and maintained at a significantly higher content than the resin of Comparative Example 1. This results in the formation of silver nanoions at the same time as the crosslinking to form the superabsorbent resin, thereby increasing the bonding strength between the superabsorbent resin itself and the silver nanoions, as well as dispersing them evenly. In particular, even after 9 days after the manufacture of some loss is still contained in a high content appeared to maintain antibacterial.

Claims (12)

1. A first step of adding and mixing vinylpyrrolidinone (VP) and a crosslinking agent to a solution containing partially or fully neutralized citraconic acid (CCA);

   A second step of adding and mixing an aqueous solution of silver nitrate to the solution obtained from the first step;

   A third step of adding and mixing a photoinitiator and ammonium persulfate to the solution obtained from the second step; And

   A fourth step of pouring the solution obtained from the third step into a mold and irradiating ultraviolet rays;

   Method for producing a super absorbent polymer having antimicrobial properties comprising a.
2. The method of claim 1,

   Vinylpyrrolidinone is added in the first step in a molar ratio of 2: 8 to 8: 2 relative to citraconic acid.
3. The method of claim 1,

   The crosslinking agent is polyethylene glycol diacrylate (PEG).
4. The method of claim 1.

   In the first step, the crosslinking agent is added in an amount of 0.3 to 1.7 wt% based on the solution containing citraconic acid and vinylpyrrolidinone.
5. The method of claim 1,

   In the second step, the silver nitrate is added in a ratio of 0.1 to 1.5 mol% relative to the total number of moles of citraconic acid and vinylpyrrolidinone.
6. The method of claim 1,

   Wherein said photoinitiator is alpha hydroxy ketone.
7. The method of claim 1,

   And a fifth step of drying the product obtained from the fourth step at 40 to 80 ° C. for 6 to 48 hours.
8. A superabsorbent polymer comprising silver nanoions and having antibacterial properties formed from citraconic acid and vinylpyrrolidinone as monomers.
9. The method of claim 8,

   Super absorbent polymer prepared by the method of any one of claims 1 to 7.
10. The method of claim 8,

    A super absorbent polymer containing the silver nano ions at a concentration of 100 to 300 ppm relative to the total resin.
11. A hygiene article made of a super absorbent polymer having antimicrobial properties of claim 8.
12. The method of claim 11,

    The hygiene product is selected from the group consisting of baby diapers, adult diapers and women's menstrual products.

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