KR20100040252A - Moisture absorbing resin characterized by high quality of absorption - Google Patents

Abstract

PURPOSE: A high moisture absorbing resin is provided to show excellent absorption capability and rate in a low humidity condition of relative humidity 30% and to ensure excellent moisture absorption capability and rate in the air. CONSTITUTION: A method for preparing a high moisture absorbing resin comprises the steps of: preparing a unsaturated monomer by neutralizing an acidic unsaturated monomer and a basic material in a molar ratio of 1 : 0.45 ~ 0.99; and polymerizing an unsaturated monomer. The basic material comprises potassium base. The potassium base is at least one selected from KOH, K2CO3, and KHCO3.

Description

Absorbent resin with excellent moisture absorption {MOISTURE ABSORBING RESIN CHARACTERIZED BY HIGH QUALITY OF ABSORPTION}

The present invention relates to a water absorbent resin having excellent moisture absorption ability and moisture absorption rate against air in the air, and a method for producing the same.

The desiccant or dehumidifying agent removes the surrounding moisture by incorporating and combining the surrounding water vapor, and is made of a hygroscopic material, and is widely used in a rainy season or a place where moisture should be removed.

Some representative moisture absorbents that are commonly used include silica gels and chemicals (calcium chloride (CaCl ₂ ), magnesium sulfate (MgSO ₄ ), magnesium chloride (MgCl ₂ )), and clay minerals (mica, diatomaceous earth, talc, quicklime). , Synthetic zeolites, natural zeolites) and oxides (magnesium oxide (MgO), iron oxide (Fe ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), silica), organic compounds (triethylamine, methylcellulose, carboxyl Methyl cellulose).

In addition, a moisture absorbent using a super absorbent polymer is also widely used. Superabsorbent resins can be prepared by neutralizing acrylic acid with a basic substance, in which sodium hydroxide or sodium carbonate is generally used as the alkali metal salt used. In particular, the use rate of the alkali metal salt was 60 to 80 mol% level compared to acrylic acid.

In order to understand more detailed absorbents to dehumidifying agents, the following prior art can be exemplified.

 Korean Patent No. KR 10-0102297 discloses a method for absorbing a calcium chloride solution produced by moisture absorption by using a superabsorbent resin together with calcium chloride in order to apply the absorbent resin as a composition for dehumidifying agent. have.

Japanese Laid-Open Patent Publication JP 1999-057465 discloses a method for dispersing a superabsorbent resin or gel in a urethane resin.

Korean Patent No. KR 10-0704235 and US Patent No. 7,326,363 disclose a method of using a resin produced by contacting a hygroscopic salt solution with a superabsorbent resin and then drying again for a dehumidifying element.

The above-mentioned conventional techniques are related to the application of the conventional super absorbent polymer as a composition for removing moisture, and do not present a method for improving the absorbency or the absorbent rate of the absorbent polymer itself. There is this.

As described above, solid dehumidifying agents such as silica gel and zeolite, and metal halide compounds such as calcium chloride and magnesium chloride have been mainly used as dehumidifying substances for removing moisture in the air.

However, the above-described conventional moisture absorbents have the following problems.

First, solid dehumidifiers such as silica gel do not have sufficient dehumidifying ability. In particular, silica gel is manufactured by decomposing sodium silicate with strong acid, so it is easy to handle, but the manufacturing cost is expensive, and it does not decompose naturally when discarded after use. There is a problem of acidification of the soil, which is currently being avoided in developed countries.

Halogen compounds such as calcium chloride (CaCl ₂ ) have excellent hygroscopicity, but because they exist as hydrates such as calcium chloride monohydrate, dihydrate, tetrahydrate, and hexahydrate in combination with moisture in the air, their use range is very limited. a problem that it requires a separate reservoir by generating melt reacts with the metal component hake ^-, can be irritating to the skin, when absorbing moisture, and changes to a liquid corrosive particular, reactive large chlorine ions (Cl) have.

Superabsorbent polymers are widely used to solve the problems of the conventional hygroscopic agent. However, superabsorbent polymers have the advantage that they are safe to human body and their properties do not change even after moisture absorption. However, the superabsorbent polymers have a problem that the hygroscopicity is lower than silica gel at low relative humidity conditions of 50% or less. In particular, the conventional water-absorbent resin has a problem of poor performance in absorbing gaseous water (there is no direct correlation between water absorption in liquid state and water absorption in gaseous state). Is true).

Accordingly, the present invention is to provide a super absorbent polymer and a method for producing the same having excellent moisture absorption and moisture absorption rate even under low humidity conditions such as 30% relative humidity.

The present invention has been made to solve the above problems of the prior art,

Preparing an unsaturated monomer by neutralizing an acidic unsaturated monomer and a basic substance in an acidic unsaturated monomer: molar ratio within the range of the basic substance = 1: 0.45 to 0.99; And

Sequentially polymerizing the unsaturated monomer;

The basic material provides a method for producing a super absorbent polymer, characterized in that it comprises a potassium base.

In addition, the present invention provides a method for producing a super absorbent polymer further comprising the step of further mixing the basic material after the step of polymerizing the unsaturated monomer.

In addition, in the present invention, the total amount of the basic material including the basic material used in the preparation of the unsaturated monomer and the basic material to be further mixed, provides a method for producing a super absorbent polymer, characterized in that less than 120 mol% compared to the acid-unsaturated monomer. do.

In addition, in the present invention, the potassium base provides a method for producing a super absorbent polymer, characterized in that one or more selected from KOH, K ₂ CO ₃ , and KHCO ₃ .

In addition, in the present invention, the acid-unsaturated monomer provides a method for producing a super absorbent polymer, characterized in that at least one selected from acrylic acid, methacrylic acid, and acrylate.

Also provided is a super absorbent polymer, which is produced by the method of the present invention.

In addition, in the present invention, the use of the super absorbent polymer provides a super absorbent polymer, characterized in that the moisture removing agent or the absorbent.

The super absorbent polymer prepared according to the present invention has an effect of exhibiting excellent hygroscopicity and hygroscopicity even under low humidity conditions. In particular, the moisture absorption and moisture absorption rate for the moisture in the air is excellent.

This application claims the benefit of the filing date of Korean Patent Application No. 10-2008-0099270 filed with the Korean Patent Office on October 9, 2008.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention,

Preparing an unsaturated monomer by neutralizing an acidic unsaturated monomer and a basic substance in an acidic unsaturated monomer: molar ratio within the range of the basic substance = 1: 0.45 to 0.99; And

Sequentially polymerizing the unsaturated monomer;

The basic material relates to a method for preparing a super absorbent polymer, characterized in that it comprises a potassium base.

In the present invention, the 'potassium base' refers to the inclusion of all potassium salts showing basicity. Representatively, the potassium base may be one or more selected from KOH, K ₂ CO ₃ , and KHCO ₃ , but is not limited thereto.

In the present invention, the basic substance contains a potassium base, and may include a sodium base or a lithium base in addition to the potassium base.

Applicants have found that the use of basic materials containing sodium and potassium, among other basic materials, is useful for improving the hygroscopicity of absorbent resins and is more effective at high neutralization conditions of 80 mol% or more. In addition, it was found that the basic material is preferred in order of lithium <sodium <potassium in terms of hygroscopic effect. In particular, it is preferable to use at least 50 mol% or more of a basic substance containing potassium, and it has been found that a better effect is obtained when using 90 mol% or more. Of course, 100 mol% of potassium base may be used as the basic substance.

The molar ratio of acrylic acid to basic material according to the basic material and the basic material in the present invention is a very important configuration.

The basic material used may have an effect even if added before the polymerization reaction, after the gel granulation step after the polymerization, or after the gel drying and grinding step.

However, when the basic material is added to have a degree of neutralization close to or higher than 100 mol%, the time required for the polymerization is long and uneven polymerization is likely to occur, which is disadvantageous in terms of productivity.

Therefore, rather than proceeding the polymerization with a degree of neutralization close to 100 mol%, the polymerization is carried out at a degree of neutralization of 90 mol%, and the basic substance is added in the gel granulation process, or the basic substance is added after the gel drying and grinding process. desirable.

However, as can be seen with reference to the examples to be described later, it is preferable that the total amount of the basic material, including the basic material used in the preparation of the unsaturated monomer and the basic material to be further mixed, is 120 mol% or less relative to the acidic unsaturated monomer. As can be seen by comparison between Example 8 and Example 9, even if the added amount is increased, the moisture absorption rate is not large, but the basicity is too high to become unstable, there is room for corrosion of the container containing the absorbent, etc. Because.

The present invention will be described in more detail with reference to the following Examples. The embodiments of the present specification are only for the detailed description of the invention and are not intended to limit the scope of the rights.

Example

Example  One

After dissolving 1.5 g of methylene bisacrylamide as an internal crosslinking agent to 500 g of acrylic acid, 1554.3 g of 20 wt% potassium hydroxide solution was added to prepare a water-soluble unsaturated monomer solution (in terms of moles), About 6.94 mol of acrylic acid, about 5.54 mol of potassium hydroxide).

The aqueous water-soluble unsaturated monomer aqueous solution was supplied to a 5 L twin arm kneader having a sigma shaft, and nitrogen gas was added for 30 minutes while maintaining at 40 ° C. to remove oxygen dissolved in the aqueous solution. While stirring, 50.1 g of 0.2 wt% L-ascorbic acid, 50.5 g of sodium persulfate solution, and 51.0 g of 2.0 wt% aqueous hydrogen peroxide solution were added. The polymerization started after 40 seconds and the resulting gel was finely divided for 30 minutes using shear force.

The finely divided gel was spread out about 30 mm thick on a stainless wire gauze having a pore size of 600 μm and dried in a 140 ° C. hot air oven for 5 hours. The dry polymer thus obtained was pulverized using a pulverizer, and classified into a standard mesh of ASTM standard to obtain a super absorbent polymer powder having a particle size of about 150 μm to 850 μm.

Example  2

Except that 1748.5g of 20% by weight potassium hydroxide solution was used in preparing the aqueous solution of water-soluble unsaturated monomer (in terms of molar units, the water-soluble unsaturated monomer solution contained about 6.94 mol of acrylic acid and about 6.23 mol of potassium hydroxide). By performing the same process as 1 to obtain a super absorbent polymer powder having a particle size of about 150㎛ ~ 850㎛.

Example 3

Except that 1360.0 g of 20 wt% potassium hydroxide solution was used in preparing the aqueous solution of the water-soluble unsaturated monomer (in terms of molar units, the aqueous solution of the water-soluble unsaturated monomer contained about 6.94 mol of acrylic acid and about 4.85 mol of potassium hydroxide), Example 1 The same process as in to obtain a super absorbent polymer powder having a particle size of about 150㎛ ~ 850㎛.

Example  4

Except that 971.4 g of 20% by weight potassium hydroxide solution was used to prepare the aqueous solution of water-soluble unsaturated monomer (in molar units, the water-soluble unsaturated monomer solution contained about 6.94 mol of acrylic acid and about 3.46 mol of potassium hydroxide). By performing the same process as 1 to obtain a super absorbent polymer powder having a particle size of about 150㎛ ~ 850㎛.

Example 5

Except for using 1179.6 g of 20% by weight sodium hydroxide solution instead of 20% by weight potassium hydroxide solution when preparing the aqueous solution of water-soluble unsaturated monomer (in terms of molar units, the aqueous solution of unsaturated monomer was about 6.94 mol acrylic acid and about 5.90 sodium hydroxide). mole), and the same process as in Example 1 to obtain a super absorbent polymer powder having a particle size of about 150㎛ ~ 850㎛.

Example  6

After dissolving 500 g of acrylic acid by adding 1.5 g of methylenebisacrylamide as an internal crosslinking agent, 874.2 g of 20% by weight potassium hydroxide solution was added to prepare a water-soluble unsaturated monomer solution (in terms of moles), About 6.94 mol of acrylic acid and about 3.17 mol of potassium hydroxide).

The aqueous water-soluble unsaturated monomer aqueous solution was supplied to a 5 L twin twin kneader having a sigma shaft, and nitrogen gas was added for 30 minutes while maintaining at 40 ° C. to remove oxygen dissolved in the aqueous solution. While stirring, 50.1 g of 0.2% by weight L-ascorbic acid, 50.5g of sodium persulfate solution and 51.0g of 2.0% by weight aqueous hydrogen peroxide solution were added. The polymerization was started after 40 seconds and the resulting gel was finely divided for 10 minutes using shear force. While stirring, 874.3 g of 20 wt% aqueous potassium hydroxide solution was sprayed and added, and the gel was finely divided for 30 minutes (in terms of molar units, the added potassium hydroxide was approximately 3.17 mol).

The finely divided gel was spread out about 30 mm thick on a stainless wire gauze having a pore size of 600 μm and dried in a 140 ° C. hot air oven for 5 hours. The dry polymer thus obtained was pulverized using a pulverizer and classified into a standard mesh of ASTM standard to obtain a super absorbent polymer powder having a particle size of 150 µm to 850 µm.

Example 7

15.6 g of 25 wt% aqueous potassium hydroxide solution was sprayed and added to the absorbent resin obtained in Example 2, and mixed evenly (in terms of molar units, the added potassium hydroxide was about 0.07 mol). Thereafter, the resultant was dried for 1 hour in a hot oven at 140 ° C. and classified into a standard mesh to obtain an absorbent resin powder having a particle size of 150 μm to 850 μm.

Example 8

To the absorbent resin obtained in Example 2, 31.2 g of a 25 wt% aqueous potassium hydroxide solution was sprayed and added and mixed evenly (in terms of molar units, the added potassium hydroxide was about 0.14 mol). Thereafter, the resultant was dried for 2 hours in a 140 ° C. hot air oven and classified with a standard mesh to obtain an absorbent polymer powder having a particle size of 150 μm to 850 μm.

Example  9

46.8 g of a 25 wt% aqueous potassium hydroxide solution was sprayed and added to the absorbent resin obtained in Example 2 and mixed evenly (in terms of molar units, additionally added potassium hydroxide was about 0.21 mol). Thereafter, the resultant was dried for 2 hours in a hot air oven at 140 ° C. and classified into a standard mesh to obtain an absorbent resin powder having a particle size of 150 μm to 850 μm.

Comparative Example 1

Except for adding 971.4 g of 20 wt% sodium hydroxide solution instead of 20 wt% potassium hydroxide solution in the preparation of the water-soluble unsaturated monomer solution (in molar units, the water-soluble unsaturated monomer aqueous solution is about 6.94 mol of acrylic acid and about sodium hydroxide). 4.85 mol) and the same procedure as in Example 1 to obtain a super absorbent polymer powder having a particle size of 150㎛ ~ 850㎛.

Comparative Example 2

Except for the addition of 582.8 g of 20 weight% lithium hydroxide solution in place of 20 weight% potassium hydroxide solution in the preparation of the water-soluble unsaturated monomer solution (in terms of molar units, the water-soluble unsaturated monomer solution is about 6.94 mol of acrylic acid and lithium hydroxide). It comprises about 4.85 mol), the same procedure as in Example 1 to obtain a super absorbent polymer powder having a particle size of 150㎛ ~ 850㎛.

Comparative Example 3

Aqueous solution of water-soluble unsaturated monomer was about 6.94 mol of acrylic acid and about lithium hydroxide, except that 749.4g of 20% by weight lithium hydroxide solution was added instead of 20% by weight potassium hydroxide solution in preparing aqueous solution of water-soluble unsaturated monomer. 6.25 mol), and the same procedure as in Example 1 to obtain a super absorbent polymer powder having a particle size of 150㎛ ~ 850㎛.

Comparative Example 4

K-SAM GS-3070H commercially available from LG Chem was used.

Comparative example  5

SXM-7500 commercially available from Stockhausen was used.

Comparative Example 6

SA-60 SXII, available from Sumitomo Chemical Co., Ltd., was used.

Comparative example  7

Aqualic CA W-101 commercially available from Nippon Catalyst Chemicals was used.

Comparative Example 8

HS-300, commercially available from Songwon, was used.

Comparative Example 9

IM-720 sold by Sandia Polymer was used.

Comparative Example 10

Hysorb 7050, available from BASF, was used.

For the Examples and Comparative Examples, the moisture absorption rate according to the relative humidity was measured for each time zone. The hygroscopicity measurement method, evenly distributed 1g of the sample in a petri-dish of 90mm in diameter, put it in each constant temperature and humidity chamber set at 32 ℃, relative humidity 30%, 50%, 70%, 30 minutes, The method of measuring the weight change after 1 hour and 3 hours, respectively, was used.

Meanwhile, the moisture absorption rate was defined as in Equation 1 below.

Table 1 shows a moisture absorption rate (%) with time at 30% relative humidity, Table 2 shows a moisture absorption rate (%) with time at 50% relative humidity, Table 3 shows a moisture absorption rate with time at 70% relative humidity. (%) Results are shown respectively.

As described in Tables 1 to 3 it can be seen that the water absorbent resin of the present invention exhibits excellent hygroscopicity. In particular, as shown in Table 1, it shows very good hygroscopicity in comparison with the comparative example in a low humidity environment.

In addition, as can be seen from Example 2 and Example 6, even if the amount of the basic material is used similarly it can be seen that it is advantageous in terms of shortening the polymerization time it is added separately before and after the monomer polymerization. That is, Example 2 and Example 6 are similar in the total amount of basic substances and their effects, but in terms of productivity, Example 6 is more advantageous because the polymerization time is shortened.

In addition, as can be seen when comparing Example 8 and Example 9, the upper limit of the amount of the added basic material is preferably 120 mol% or less compared to the acid unsaturated unsaturated monomer. That is, above this range, even if the amount of additional basic substances increases, it is almost equivalent level in moisture absorption rate.

Claims (7)

Preparing an unsaturated monomer by neutralizing an acidic unsaturated monomer and a basic substance in an acidic unsaturated monomer: molar ratio within the range of the basic substance = 1: 0.45 to 0.99; And Sequentially polymerizing the unsaturated monomer; The basic material is a method for producing a super absorbent polymer, characterized in that it comprises a potassium base. The method of claim 1, further comprising the step of further mixing the basic material after the step of polymerizing the unsaturated monomer. The method for producing a super absorbent polymer according to claim 2, wherein the total amount of the basic substance including the basic substance used in preparing the unsaturated monomer and the basic substance to be further mixed is 120 mol% or less with respect to the acidic unsaturated monomer. The method of claim 1, wherein the potassium base is at least one selected from KOH, K ₂ CO ₃ , and KHCO ₃ . The method of claim 1, wherein the acid-unsaturated monomer is one or more selected from acrylic acid, methacrylic acid, and acrylate. A super absorbent polymer, which is prepared by the method of claims 1 to 5. 7. The super absorbent polymer according to claim 6, wherein the superabsorbent polymer is a moisture scavenger or a hygroscopic agent.