KR101983259B1 - Low-temperature curable surface cross-linking agent of super absorbent polymer and preparing method of low-temperature curable surface cross-linking agent of super absorbent polymer - Google Patents

Abstract

Disclosed is a preparation method of a low-temperature curing surface crosslinking agent of a superabsorbent resin, which comprises: a first step of mixing polyhydric alcohol and a Lewis acid catalyst at 30-40°C; a second step of adding epichlorohydrin to the mixture of the first step, and making reaction at 60-90°C to obtain halohydrin ether; a third step of adding a quaternary ammonium salt to halohydrin ether obtained in the second step and make reaction at 50-60°C; a fourth step of adding a strongly alkaline aqueous solution to a resultant product of the reaction in the third step to make condensation reaction; a fifth step of dividing the reaction product obtained in the fourth step into a salt layer and a resin layer including epichlorohydrin by using a dry filter at 40-60°C; a sixth step of recovering and removing excess of epichlorohydrin from the resultant product obtained in the fifth step; and a seventh step of adding an alkali absorbent to the resultant product obtained in the sixth step to perform mixing at 65-80°C. The fourth step of making condensation reaction includes: an A step of adding to the reaction product obtained in the third step a strongly alkaline aqueous solution as much as one third of strongly alkaline aqueous solution necessary for reaction with halohydrin ether to remove a salt water layer; and a B step of adding to the reaction product obtained in the A step a strongly alkaline aqueous solution as much as two-thirds of a strongly alkaline aqueous solution necessary for reaction with halohydrin ether to perform a decompression and dehydration process, wherein a reaction temperature in the B step is controlled to increase relative to the reaction temperature of the A step.

Description

TECHNICAL FIELD [0001] The present invention relates to a low-temperature curable surface cross-linking agent for a superabsorbent resin and a method for preparing the same, and a method of preparing the cross-

The present invention relates to a surface cross-linking agent capable of curing at a low temperature of a superabsorbent resin and a method for producing the same.

Since the absorption of the superabsorbent polymer (SAP) to the pressure and the improvement of the swelling rate of the SAP are determined by the surface cross-linking of the SAP particles, the external surface cross-linking is generally the last step of the process, The particle size is important and the curing temperature and speed of the surface cross-linking agent are very important. When the surface cross-linking agent is cured in a solution state, it becomes a particle form. The coating operation on the surface of the SAP particles requires a surface cross-linking agent having a low-temperature fast curing property in order to obtain a high-quality base polymer in accordance with the characteristics of the product. However, there are ethylene peroxide, 1,3-propanediol, propylene glycol, and adipamide series as the surface cross-linking agent that reacts with the carboxyl group of the superabsorbent resin skeleton using the known polyhydric alcohol as the starting material, A condition of 180 DEG C or more is required, which is not preferable from the viewpoints of economy and productivity. In addition, ethylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether have been developed and used as surface cross-linking agents capable of low-temperature curing. However, since it is difficult to obtain yield and process control in the conventional production method, And the content of contaminating sub-fraction is not less than 10000 ppm, which inhibits or delays the reactivity of functional groups such as the carboxyl group of the base resin of the superabsorbent resin with the epoxide functional group, which is not preferable for rapid curing. A high-purity, low temperature curable surface cross-linking agent is required to obtain high quality polymers, that is, polymers capable of low-temperature curing with low extraction and low residue.

However, the surface crosslinking agents known so far can be cured at a low temperature, but they are problematic from the viewpoint of economical efficiency due to the need of post-curing due to a delay in curing time. This is because the water- The epoxy equivalent and the content of subcomponent are high and the surface of the particles of the superabsorbent resin is not evenly coated due to the insoluble components during the water-solubilization so that the surface cross-linking may not be completed completely. In order to reduce this, there is not known a manufacturing method in which high yield, high purity, and generation of wastewater are minimized because excessive resin loss and malicious wastewater can not be prevented when the washing process is repeated.

Accordingly, it is an object of the present invention to provide a low-temperature curing type surface crosslinking agent of a superabsorbent resin which maximizes economic efficiency and productivity of a superabsorbent resin manufacturing plant, because it can be cured at low temperatures and reduces the time required for complete curing.

According to an aspect of the present invention, there is provided a process for producing a polyisocyanate comprising mixing a polyhydric alcohol and a Lewis acid catalyst at 30 to 40 캜; A second step of adding epichlorohydrin to the mixture of the first step and conducting a reaction at 60 to 90 ° C to obtain a halohydrin ether; Adding a quaternary ammonium salt to the halohydrin ether obtained in the second step and reacting it at 50 to 60 ° C; A fourth step of adding a strong alkaline aqueous solution to the reaction product of the third step followed by a condensation reaction; A fifth step of separating the reaction product obtained in the fourth step from the salt layer containing epichlorohydrin and the salt layer using a dry filter at 40 to 60 ° C; A sixth step of recovering and removing excess epichlorohydrin from the result obtained by the fifth step; And a seventh step of adding an alkali adsorbent to the resultant obtained in the step 6 and mixing the resultant at 65 to 80 ° C,

In the fourth step of performing the condensation reaction, a strong alkaline aqueous solution corresponding to 1/3 of the strong alkaline aqueous solution required for the reaction with the halohydrin ether is added to the reaction product obtained in the third step, and a solution A step; And a B step of adding a strong alkaline aqueous solution corresponding to 2/3 of the strong alkaline aqueous solution required for the reaction with the halohydrin ether to the reaction product obtained in the step A and further comprising a reduced pressure dehydration step, Wherein the reaction temperature is controlled so as to be increased as compared with the reaction temperature of the step (A), wherein the low temperature curing type surface crosslinking agent of the superabsorbent resin is provided.

Another object of the present invention is to provide a superabsorbent resin surface cross-linking agent which is produced by the above-mentioned production method and which has a theoretical epoxy equivalent of not more than 130%, a hydrolyzable chlorine content of not more than 3000 ppm, a yield of not less than 90% % Or more of the surface cross-linking agent.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain an excellent affinity for an organic solvent and water, and to obtain a high-purity superabsorbent resin surface cross-linking agent with excellent efficiency. As described above, the superabsorbent resin surface cross-linking agent obtained according to the present invention can be used for a crosslinking agent, a crosslinking accelerator, a viscosity adjusting agent, a hardening property improving agent, etc. of an acrylic resin and a urethane resin. Do.

Hereinafter, the low-temperature curing type surface cross-linking agent of the super absorbent resin of the present invention and the method for producing the same will be described in more detail.

The method for producing a low temperature curable surface crosslinking agent of the present invention comprises a first step of mixing a polyhydric alcohol and a Lewis acid catalyst at 30 to 40 캜; A second step of adding epichlorohydrin to the mixture of the first step and conducting a reaction at 60 to 90 ° C to obtain a halohydrin ether; Adding a quaternary ammonium salt to the halohydrin ether obtained in the second step and reacting it at 50 to 60 ° C; A fourth step of adding a strong alkaline aqueous solution to the reaction product of the third step followed by a condensation reaction; A fifth step of separating the reaction product obtained in the fourth step from the salt layer containing epichlorohydrin and the salt layer using a dry filter at 40 to 60 ° C; A sixth step of recovering and removing excess epichlorohydrin from the result obtained by the fifth step; And a seventh step of adding an alkali adsorbent to the resultant obtained in the sixth step and mixing at 65 to 80 캜.

In the fourth step of performing the condensation reaction, a strong alkaline aqueous solution corresponding to 1/3 of the strong alkali aqueous solution required for the reaction with the halohydrin ether is added to the reaction product obtained in the third step, and the intermediate and the brine layer are removed And a step B of adding a strong alkaline aqueous solution corresponding to 2/3 of the strong alkali aqueous solution required for the reaction with the halohydrin ether to the reaction product obtained in the step A, . Wherein the reaction temperature of step B is controlled to be higher than the reaction temperature of step A above.

In the reaction of adding the epichlorohydrin in the presence of the polyhydric alcohol and the Lewis acid catalyst in the second step, the generation of the polymerized product due to the discoloration or the side reaction and the chlorine content of the final product may be increased due to the rapid heat generation, To maintain, the cooling and heating must be repeated continuously.

In order to prevent the above-mentioned problems, the present inventors conducted a reaction in which excess epichlorohydrin was added in the range of 1 hour to 2 hours at 60 to 90 ° C in the presence of a polyhydric alcohol and a Lewis acid catalyst, The reaction temperature by the addition can be controlled to minimize discoloration, inhibit the formation of polymerizates, and add excess epichlorohydrin to minimize the low molecular weight and hydrolyzable chlorine content.

The polyhydric alcohol may be at least one selected from compounds represented by the following general formulas (1a) to (1d), particularly preferably a polyhydric alcohol having two or more hydroxyl groups.

[Chemical Formula 1a] [Chemical Formula 1b]

Wherein R ₁ is -H and R 2 is -OH, R ₃ is -H, R ₄ is -OH,

[Chemical Formula 1c] [Chemical Formula 1d]

상기 화학식 1c중, R₅은 -H이고, R₆는 -OH이고, 상기 화학식 1d 중, R₇는 ­H이고, R₈는 ­OH이다.

In the above formula (1c), R ₅ is -H and R ₆ is -OH, wherein R ₇ is H and R ₈ is OH.

The epichlorohydrin may be represented by the following formula (2).

[Formula 2]

Wherein R ₉ is -OH or Cl.

BF ₃ and its complex salts such as BF ₃ .Et ₂ O, BF ₃ .H ₂ O, Sn (BF ₄ ), and the like can be used as non-limiting examples of the Lewis acid catalyst used in the reaction of the polyhydric alcohol and epichlorohydrin. _{2, Fe (BF 4) 2} , Ca (BF 4) 2, Zn (BF 4) 2, Mg (BF 4) 2, Cu (BF 4) 2, and the like of tin chloride, particularly Sn (BF _{4) 2, Fe (BF 4) 2} , Ca (BF 4) 2, Zn (BF 4) 2, Mg (BF 4) 2, it is more preferable from the reactivity to use a Cu (BF _{4) 2.} the Lewis acid The content of the catalyst is preferably 500 to 1500 ppm based on 100 parts by weight of epichlorohydrin.

The content of epichlorohydrin is in the range of 8.0 to 12 mol based on 1 mol of ethylene glycol in the case of ethylene glycol and 6.5 to 8.5 mol based on 1 mol of diethylene glycol in the case of diethylene glycol. 1000) is 6.0 mol to 8.0 mol based on 1 mol of polyethylene glycol. And is 6.0 to 8.0 mol based on 1 mol of isobide in the case of isobide. If the content of epichlorohydrin is less than 6.5 mol based on the reaction mole ratio of less than the polyhydric alcohol molecular weight (Mw 400), the initial heat generation is difficult to control and the molecular weight due to the side reaction becomes abnormally large, The chlorine content increases. A purity exceeding 12 moles on a molar basis of less than the molecular weight of polyhydric alcohol (Mw 400) may improve purity, but there may be a large amount of unreacted residues resulting in the loss of epichlorohydrin. On the other hand, if the molecular weight of the polyhydric alcohol is higher than 8.5 mol, unreacted epichlorohydrin loss may occur.

The reaction temperature of the polyhydric alcohol and epichlorohydrin is 60 to 90 ° C, more preferably 65 to 80 ° C, as described above. If the reaction temperature is less than 60 캜, the reactivity of epichlorohydrin and polyhydric alcohol is extremely low due to the presence of a large amount of unreacted products. If it exceeds 90 DEG C, there is a risk of discoloration, and formation of an isomer is large, which is undesirable because the intermediate reaction is formed in a secondary reaction by a strong alkali catalyst. The reaction time is somewhat variable depending on the reaction temperature, and the reaction time is about 1 to 2 hours, preferably about 0.5 to 1.5 hours.

The content of water contained in the polyhydric alcohol and epichlorohydrin is 1% by weight or less, particularly 0.1 to 0.5% by weight, from the viewpoint of reactivity.

And then aging the halohydrin ether obtained in the second step at 60 to 90 占 폚. If the quaternary ammonium salt is added in the third step and then the step A and the step B are sequentially carried out, the following advantages can be obtained. have. Step A in the fourth step activates the initial reaction rate in the aqueous solution state, shortens the separation time at the time of the removal of the brine layer after completion of the reaction, and clarifies the separating line. In step B of the fourth step, a decompression dehydration step is carried out to minimize the formation of isomers in the presence of water and salt due to the nature of the water-soluble crosslinking agent, thereby suppressing the formation of an intermediate product and obtaining an optimum effect having a low epoxy equivalent and a high water- . If the condensation reaction of the halohydrin ether is carried out in one stage of the strong alkaline aqueous solution and the reduced pressure dehydration reaction without performing the step A and the step B as described above, the reaction activity due to the initial dehydration is lowered Glycerolization by the strong alkali in unreacted state and the resulting salt proceeds extremely, and as a result, an intermediate product is extremely generated. Therefore, the phase separation line is not clear and the yield is lowered, the production of coagulation residues by high chlorine and generation of waste water are very disadvantageous .

The quaternary ammonium salt is at least one selected from, for example, benzyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium hydroxide, benzyltriethylammonium hydroxide, or a combination thereof. The content of the quaternary ammonium salt may be selected from reaction temperature, For example, 0.5 to 20 parts by weight, for example, 1 to 10 parts by weight, for example, 1.5 to 5 parts by weight, based on 100 parts by weight of the halohydrin ether. The addition of the quaternary ammonium salt provides an advantage that the phase separation of the resin layer, the intermediate product and the salt layer can be performed quickly and clearly as the homogeneous reaction is achieved in the epoxidation reaction between the produced halohydrin ether and the 50% strong alkali aqueous solution . The quaternary ammonium salt may be used in an aqueous solution having a concentration of 5 to 70% by weight.

The use of the quaternary ammonium salt improves the reactivity of the halohydrin ether as the composition of the reaction mixture becomes uniform.

As the strong alkali, sodium carbonate, potassium carbonate, sodium hydroxide, calcium hydroxide, potassium hydroxide or a mixture thereof is used, and a 50% strong alkali aqueous solution can be prepared by dissolving the above-mentioned strong alkali in water. The strong alkali is a 50 wt% aqueous solution of sodium hydroxide. In this case, the content of the strong alkali is preferably 1.9 to 2.5 mol based on 1 mol of the polyhydric alcohol based on 100% of the solids.

Then, the reaction product obtained in the fourth step is subjected to a fifth step of separating the salt water layer and the resin layer containing epichlorohydrin using a dry filter, and recovering and removing epichlorohydrin from the resultant product The alkali adsorbent is added from the result obtained in steps 6 and 6, mixed at 65 to 80 ° C, and passed through a microfilter to produce a desired low-temperature curable surface cross-linking agent of a superabsorbent resin.

In the present specification, the low-temperature curing type refers to a case where a curing reaction occurs at 180 ° C or lower. The low temperature curing type is, for example, a low temperature curing method and the low temperature curing means that curing is performed at a low temperature in a short time, and the curing time is, for example, a range of 1 to 60 minutes.

The separation and removal of the salt (sodium chloride) and the excess epichlorohydrin via the epoxidation step is carried out by separating two times in order to isolate using a filter drier or Lucie filter, In order to remove chlorohydrin, the recovered temperature is preferably 110 to 140 ° C. When the temperature exceeds 140 ° C, there is a risk of discoloration and resin loss. The decompression range is preferably in the range of 250 to 350 torr initially, and the residual epichlorohydrin When the residual epichlorohydrin is completely recovered, the reaction mixture is cooled. Then, an alkali adsorbent is added thereto at 65 to 80 ° C, mixed and stirred, and then passed through a 5 μm filter Whereby a desired superabsorbent resin low temperature surface cross-linking agent can be obtained.

Synthetic hydrotalcite is used as the alkali adsorbent. Synthetic hydrotalcide is commercially available under the trade name Kyoword 700SL (manufactured by Kyowa Chemical Industry Co., Ltd).

According to another aspect of the present invention, a low-temperature curing type surface cross-linking agent of a high-purity superabsorbent resin obtained by the above production method can be obtained. The surface cross-linking agent has an epoxy equivalent of 130% or less, a hydrolyzable chlorine content of 3,000 ppm or less, a yield of 90% or more, and a solubility (water-solubility) in water of 1000% or more.

Hereinafter, the surface cross-linking reaction of the superabsorbent resin using the surface cross-linking agent will be described.

The surface crosslinking agent has two or more functional groups capable of reacting with a carboxyl group present in the skeleton of the superabsorbent resin. When the surface cross-linking reaction of the superabsorbent resin is carried out using the surface cross-linking agent, a surface treatment film having a high cross-linking density is formed on the surface of the superabsorbent resin particles. The superabsorbent resin in which the surface treatment film is disposed has a core-shell structure. Is a primary crosslinked polymer of superabsorbent resin particles, and the shell exhibits a high crosslinking density on the surface.

The SAP particles having the surface treatment film formed using the surface cross-linking agent of the present invention provide high quality base polymer, i.e., low extraction, low residual desired properties. The surface cross-linking reaction proceeds under low-temperature, short-time reaction conditions, which is preferable in terms of economy and productivity.

The content of the surface crosslinking agent is 0.001 to 5.0 parts by weight, for example, 0.01 to 3 parts by weight, based on 100 parts by weight of the base resin of the superabsorbent resin.

 The highly water-absorbent resin is a polymer formed by partially crosslinking a water-soluble polymer, and has a three-dimensional network structure and a large amount of hydrophilic groups, and has water insolubility and hydrophilicity at the same time.

The surface-crosslinked superabsorbent resin can be prepared by mixing and reacting a base resin of a superabsorbent resin, a surface cross-linking agent, a water-soluble salt containing a polyvalent cation, and a polycarboxylic acid-based copolymer.

The content of the polycarboxylic acid copolymer is 0.001 to 5.0 parts by weight based on 100 parts by weight of the base resin of the superabsorbent resin.

The base resin of the superabsorbent resin can be obtained by polymerizing a water-soluble ethylenically unsaturated monomer and a monomer composition containing a polymerization initiator by heat or light to prepare a hydrogel polymer, drying and pulverizing the dried product.

A water-soluble salt containing a polyvalent cation, a polycarboxylic acid-based copolymer, a base resin of a superabsorbent resin and a method for producing the same are the same as those disclosed in Korean Patent No. 10-1820051.

Further, by using the method for producing a low-temperature curing type surface crosslinking agent of the present invention, it is possible to obtain a high-absorptive resin surface crosslinking agent having excellent affinity for an organic solvent and water with excellent yield and high purity of an object, It is possible to minimize isomer content.

The superabsorbent resin having the surface cross-linking agent according to the present invention can greatly reduce the time and cost of the process, and the absorption characteristics (centrifugal retention capacity (CRC) and absorption under pressure Due to the improving effect, the properties of the process performance excellent in comparison with the conventional super absorbent resin are improved.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but it should be understood that the present invention is not limited to the following examples.

Example  One

Lewis acid catalyst BF ₃ .Et ₂ O (500 ppm / epichlorohydrin) was added to 124 g of ethylene glycol in a 2 L four-necked flask equipped with a reflux condenser. The mixture was mixed at 35 ° C. and 1,850 g of epichlorohydrin was reacted The mixture was added at a temperature of 75 占 폚 for 1 hour and aged for 2 hours after completion to obtain a halohydrin ether. Subsequently, the temperature of the resultant was lowered to about 55 ° C, and 37.0 g of a 50% by weight aqueous benzyltriethylammonium chloride solution was added thereto, and the reaction was carried out for 1 hour. The content of benzyltriethylammonium chloride is 2.0 parts by weight based on 100 parts by weight of the halohydrin ether.

The condensation reaction of the reaction mixture (glycidylation reaction of halohydrin ether) was carried out in the following steps A and B, respectively.

214 g of a 50 wt% aqueous solution of sodium hydroxide was added to the reaction product at 55 ° C for 1.0 to 1.5 hours to carry out a condensation reaction. Then, it was aged at 55 ° C for 1 hour. Subsequently, 624.7 g of water was added thereto, stirred, allowed to stand for 0.5 hour, and then the brine layer was removed (step A).

Subsequently, 426 g of a 50% by weight aqueous solution of sodium hydroxide was added to the reaction mixture, followed by a reduced-pressure dehydration process at about 65 ° C. The reduced-pressure dehydration process was performed for about 2 hours (Step B)

Subsequently, the decompression was released from the reaction product, the solution was cooled, and the dry filter was repeatedly passed through at 50 ° C twice to separate the brine layer and the resin layer containing epichlorohydrin. The resin layer containing the separated epichlorohydrin was added to the reactor, epichlorohydrin was recovered from the reaction mixture under reduced pressure, 0.8 g of Synthetic Word 700SL as an alkali adsorbent was added, and the mixture was stirred for 30 minutes, To obtain 323 g of a low temperature curable surface crosslinking agent of a superabsorbent resin (yield: 92%).

Comparative Example  One

The aqueous phase of the reaction mixture was removed without removing the aqueous phase of the A-phase, and the epichlorohydrin was recovered. 0.8 g of Synthetic 700SL, which is an alkali adsorbent, was added to the reaction mixture for 30 minutes Followed by mixing and stirring to obtain a low temperature curing type surface crosslinking agent of a superabsorbent resin using a 5 탆 filter. The procedure of Example 1 was repeated except that the pressure in the step B was not changed.

Comparative Example  2

In both steps A and B without separating into steps A and B, a vacuum dehydration reaction was carried out

, The same procedure as in Example 1 was carried out.

Example  2

Lewis acid catalyst BF ₃ .Et ₂ O (500 ppm / epichlorohydrin) was added to 159 g of diethylene glycol in a 2 L four-necked flask equipped with a reflux condenser, and the mixture was mixed at 35 ° C., and 1,020 g of epichlorohydrin The mixture was added at a reaction temperature of 75 캜 for 1 hour and aged for 2 hours after completion. Subsequently, the temperature of the resultant was lowered to about 55 ° C, 20.4 g of a 50% by weight aqueous solution of benzyltriethylammonium chloride was added, and the reaction was carried out for 1 hour.

The condensation reaction of the reaction mixture (glycidylation reaction of halohydrin ether) was carried out in the following steps A and B, respectively.

84 g of a 50 wt% aqueous solution of sodium hydroxide was added to the reaction product at 55 ° C for 1.0 to 1.5 hours to carry out a condensation reaction. Subsequently, the mixture was aged at 55 DEG C for 1 hour. Then, 294 g of water was added thereto, stirred, allowed to stand for 0.5 hour, and then the brine layer was removed (step A).

Subsequently, 168 g of a 50% by weight aqueous solution of sodium hydroxide was added to the reaction mixture, followed by a reduced pressure dehydration process at about 65 캜. The reduced pressure dehydration process was performed for about 2 hours (Step B).

Subsequently, the decompression was released from the reaction product, the solution was cooled, and the dry filter was repeatedly passed through at 50 ° C twice to separate the brine layer and the resin layer containing epichlorohydrin. The resin layer containing the separated epichlorohydrin was added to the reactor, epichlorohydrin was recovered from the reaction mixture under reduced pressure, and 0.62 g of Synthetic Word 700 SL as an alkali adsorbent was added thereto. The mixture was stirred for 30 minutes, To obtain 254 g of a low temperature curable surface crosslinking agent of a superabsorbent resin (yield: 93%).

Comparative Example  3

Without separating into the A and B stages and without removing the brine layer in the A stage,

After removing the brine layer of the obtained reaction mixture, epichlorohydrin was recovered and 0.8 g of Syowword 700 SL, which is an alkali adsorbent, was added and mixed and stirred for 30 minutes. Using a 5 탆 filter, a low temperature curing type surface crosslinking agent . The procedure of Example 2 was repeated except that the pressure was not reduced in Step B in Example 2.

Comparative Example  4

In both steps A and B without separating into steps A and B, a vacuum dehydration reaction was carried out

The procedure of Example 2 was repeated except that

Example  3

Lewis acid catalyst BF ₃ .Et ₂ O (500 ppm / epichlorohydrin) was added to 500 g of polyethylene glycol in a 2 L four-necked flask equipped with a reflux condenser, and the mixture was stirred at 35 ° C. Then 323.8 g of epichlorohydrin was reacted The mixture was added at a temperature of 75 캜 for 1 hour and aged for 2 hours after completion. Subsequently, the temperature of the resultant was lowered to about 55 ° C, and then 6.5 g of a 50% by weight aqueous solution of benzyltriethylammonium chloride was added and the reaction was carried out for 1 hour.

The condensation reaction of the reaction mixture (glycidylation reaction of halohydrin ether) was carried out in the following steps A and B, respectively.

23.3 g of a 50 wt% aqueous solution of sodium hydroxide was added to the reaction product at 55 ° C for 1.0 to 1.5 hours to carry out a condensation reaction. Subsequently, the mixture was aged at 55 캜 for 1 hour. Then, 81.5 g of water was added thereto, stirred, allowed to stand for 0.5 hour, and then the brine layer was removed (step A).

Subsequently, 46.7 g of a 50% by weight aqueous solution of sodium hydroxide was added to the reaction mixture, which was subjected to a reduced pressure dehydration process at about 65 ° C, and the reduced pressure dehydration process was conducted for about 2 hours (Step B).

Subsequently, the decompression was released from the reaction product, the solution was cooled, and the dry filter was repeatedly passed through at 50 ° C twice to separate the brine layer and the resin layer containing epichlorohydrin. The resin layer containing the separated epichlorohydrin was added to the reactor, epichlorohydrin was recovered from the reaction mixture under reduced pressure, and 2.2 g of Synthetic Word 700SL, which is an alkali adsorbent, was added and stirred for 30 minutes, 552 g of a low temperature curing type surface crosslinking agent of a superabsorbent resin was obtained (yield: 94%).

Comparative Example  5

The aqueous phase of the reaction mixture was removed without removing the aqueous phase of the A-phase, and the epichlorohydrin was recovered. 0.8 g of Synthetic 700SL, which is an alkali adsorbent, was added to the reaction mixture for 30 minutes Followed by mixing and stirring to obtain a low temperature curing type surface crosslinking agent of a superabsorbent resin using a 5 탆 filter. Example 3 was carried out in the same manner as in Example 3, except that the decompression of Step B was not carried out.

delete

Comparative Example  6

In both steps A and B without separating into steps A and B, a vacuum dehydration reaction was carried out

Except one. The procedure of Example 3 was repeated.

Example  4

In a 2 L four-necked flask equipped with a reflux condenser, Lewis acid catalyst BF ₃ .Et ₂ O (500 ppm / epichlorohydrin) was added to 236 g of isosorbide represented by the formula (1d) and mixed at 35 ° C 647.5 g of epichlorohydrin was added at a reaction temperature of 75 캜 for 1 hour, and aging was performed for 2 hours after completion. Then, the temperature of the resultant was lowered to about 55 占 폚, and 12.9 g of a 50% by weight aqueous solution of benzyltriethylammonium chloride was added thereto, and the reaction was carried out for 1 hour.

The condensation reaction of the reaction mixture (glycidylation reaction of halohydrin ether) was carried out in the following steps A and B, respectively.

58.6 g of a 50 wt% aqueous solution of sodium hydroxide was added to the reaction product at 55 ° C for 1.0 to 1.5 hours to carry out a condensation reaction. Subsequently, the mixture was aged at 55 ° C for 1 hour. Then, 205.3 g of wash water was added thereto, stirred, allowed to stand for 0.5 hours, and then the brine layer was removed (step A).

Next, 117.2 g of a 50% by weight aqueous solution of sodium hydroxide was added to the reaction mixture, followed by a reduced pressure dehydration process at about 65 캜. The reduced pressure dehydration process was performed for about 2 hours (Step B).

Subsequently, the decompression was released from the reaction product, the solution was cooled, and the dry filter was repeatedly passed through at 50 ° C twice to separate the brine layer and the resin layer containing epichlorohydrin. The resin layer containing the separated epichlorohydrin was added to the reactor, epichlorohydrin was recovered from the reaction mixture under reduced pressure, 1.6 g of Synthetic 700SL as an alkali adsorbent was added thereto, and the mixture was stirred for 30 minutes, To obtain 372 g of a low temperature curable surface crosslinking agent of a superabsorbent resin (yield: 93%).

Comparative Example  7

Without separating into the A and B stages and without removing the brine layer in the A stage,

After removing the brine layer of the obtained reaction mixture, epichlorohydrin was recovered and 0.8 g of Syowword 700 SL, which is an alkali adsorbent, was added and mixed and stirred for 30 minutes. Using a 5 탆 filter, a low temperature curing type surface crosslinking agent . Example 4 was carried out in the same manner as in Example 4, except that the decompression in Step B was not carried out.

Comparative Example  8

The same procedure as in Example 4 was carried out except that the A and B stages were not classified into A and B stages but the A and B stages were subjected to a reduced pressure dehydration reaction.

delete

Comparative Example  9

The procedure of Example 1 was repeated except that the reaction temperature in Step A was changed to 65 占 폚 and the reaction temperature in Step B was changed to 55 占 폚.

Comparative Example  10

The procedure of Example 1 was repeated except that the temperature of the halohydrin ether was lowered to about 55 ° C and then 37.0 g of 50 wt% benzyltriethylammonium chloride aqueous solution was added thereto. The same procedure was carried out except that.

Example  5 and 6

The procedure of Example 1 was repeated except that the amount of benzyltriethylammonium chloride in the aqueous solution of benzyltriethylammonium chloride was 5 parts by weight and 10 parts by weight based on 100 parts by weight of the halohydrin ether.

Evaluation example  One

The epoxy equivalent, the hydrolyzable chlorine content, the total chlorine content, the water content, the viscosity and the water dissolution rate of the low temperature curable surface crosslinking agent of the superabsorbent resin obtained in Example 1-6 and Comparative Example 1-10 were measured. Results for Examples 1-4 Results for Comparative Examples 1 to 10 are also shown in Table 1 below.

The epoxy equivalent weight was measured using a 0.1N NaOH solution titration method. The hydrolyzable chlorine content, total chlorine content, and water content were measured using Karl-Fusher method, and the viscosity was measured with a Brookfield viscometer. And the degree of water solubility was measured by dissolving 10 g of the superabsorbent resin cross-linking agent in 90 g of water (25 ° C.).

As a result of measurement, epoxy equivalent, hydrolyzable chlorine content, total chlorine content, water content, color, water dissolution rate and yield of the surface cross-linking agent of the superabsorbent resin are shown in Table 1, respectively.

division Epoxy equivalent (g / eq) Hydrolyzable chlorine content (ppm) Total chlorine content (wt%) Moisture content
(wt%) color
(APHA) Hardening rate (wt%) yield
(%) Example 1 111.5 2,500 0.5 0.01 20 ∞ 92 Example 2 123.4 2,100 0.4 0.01 30 ∞ 93 Example 3 561.2 1,500 0.3 0.02 20 ∞ 93 Example 4 153.9 1,250 0.2 0.01 30 <2000 93 Example 5 112.3 2,700 0.5 0.01 20 ∞ 90 Example 6 112.4 3,100 0.6 0.02 20 ∞ 90 Comparative Example 1 1Gel35.3 5,200 1.7 0.03 30 90 24 Comparative Example 2 117.5 7,900 3.5 0.02 40 100 51 Comparative Example 3 168.9 5,500 1.6 0.02 30 80 18 Comparative Example 4 131.4 10,150 5.7 0.02 70 120 42 Comparative Example 5 735.4 2,050 0.9 0.04 50 100 29 Comparative Example 6 653.8 6,440 2.2 0.03 40 140 55 Comparative Example 7 195.3 2,430 1.1 0.03 60 90 27 Comparative Example 8 171.7 7,150 3.3 0.03 60 110 51 Comparative Example 9 131.1 8,750 4.4 0.05 70 <500 68 Comparative Example 10 129.9 5,520 1.8 0.03 70 ∞ 58

In Table 1, ∞ means infinity.

Referring to Table 1, according to Comparative Example 1, as the reaction progressed without removing the intermediate of Example 1 in the strong alkaline addition reaction, the side reaction was promoted by the salt and the residual moisture, resulting in a high epoxy equivalent, The intermediate product was much separated and the salt and the separating liquid were not clear, so that the intermediate product was separated and removed to give a high epoxy equivalent and a high chlorine content as compared with Example 1, and the yield was less than 30% 2, the reaction between the unreacted alkali and salt by the vacuum dehydration condensation reaction from the beginning in the strong alkaline addition reaction continuously forms the isomer during the reaction, and the glycerolization reaction with the unreacted epichlorohydrin by the alkali 1, the chlorine content was 3 times or more higher than that in Example 1, and the mixed water in the produced water and strong alkaline aqueous solution was statistically removed The yield of the final product was as low as 50%, although the Foxy equivalent was lower than that of Comparative Example 1. According to Comparative Example 3, as the reaction progressed without removing the intermediate of Example 2 in the strong alkaline addition reaction, the side reaction was promoted by the salt and the residual moisture, resulting in a high epoxy equivalent, As a result, the intermediate product was separated and removed. As a result, the final product had a high epoxy equivalent and a high chlorine content as compared with Example 2, and an extremely low yield of less than 18% was obtained. In the case of Comparative Example 4, in the strong alkaline addition reaction, the unreacted alkali by the vacuum dehydration condensation reaction from the beginning forms a continuous isomer during the reaction, and the glycerolization reaction with the unreacted epichlorohydrin by the alkali The chlorine content was 3 times or more higher than that in Example 2, and the amount of water in the produced water and the strong alkaline aqueous solution was statistically lowered, so that the epoxy equivalent was lower than Comparative Example 3, but the yield of the final product was 42% Low results were obtained.

On the other hand, according to Comparative Example 5, as the reaction proceeds without removing the intermediate in the strong alkaline addition reaction of Example 3, a side reaction is promoted by the salt and the residual moisture, resulting in a high epoxy equivalent. The intermediate product was separated and removed in the same manner as in Example 3. As a result, compared with Example 3, the final product had a high epoxy equivalent and a high chlorine content, and an extremely low yield of less than 29% .

In the case of Comparative Example 6, in the strong alkaline addition reaction, the unreacted alkali by the vacuum dehydration condensation reaction from the beginning forms a continuous isomer during the reaction, and the glycerolization reaction with the unreacted epichlorohydrin due to alkali The chlorine content was 3 times or more higher than that in Example 3 and the mixed water in the produced water and strong alkaline aqueous solution was statistically removed to show that the epoxy equivalent was lower than Comparative Example 5 but the yield of the final product was as low as 55% Results were obtained. According to Comparative Example 7, as the reaction progressed without removing the intermediate in the strong alkaline addition reaction of Example 4, the side reaction was promoted by the salt and the residual moisture, resulting in a high epoxy equivalent, As a result, the final products were found to have high epoxy equivalent and chlorine content as compared with Example 3, and an extremely low yield of less than 27% was obtained. In the case of Comparative Example 8, in the strong alkaline addition reaction, from the beginning, the unreacted alkali by the dehydration condensation reaction and the salt form an isomer continuously during the reaction, and the glycerolization reaction with the unreacted epichlorohydrin by alkali The chlorine content of 3 times or more was higher than that of Example 3, and the mixed water in the generated water and strong alkaline aqueous solution was statistically removed, and the epoxy equivalent was lower than that of Comparative Example 7, but the yield of the final product was as low as 51% Results were obtained. According to Comparative Example 9, when the reaction was accelerated in the step A and the side reaction proceeded rapidly, there was a lot of intermediate formation during the separation. In the step B, the decompression reaction at the low temperature resulted in the dehydration amount being less than the theoretical value and the reaction time being long As a side reaction between the salt layer formed and the remaining strong alkali progressed, the yield of the glycolized isomer was increased, resulting in a relatively low yield of 68%. According to Comparative Example 10, when the salt layer was separated in Step A, Uncertainly, resin layer loss occurred and yield was 58% lower. On the other hand, the yields of the surface cross-linking agent according to Examples 1 to 4 were greatly increased as compared with the cases of Comparative Examples 1 to 8, and the rate of hydrolysis was improved. And the total chlorine content and hydrolyzable chlorine content were decreased.

The results are shown in Tables 1 and 2, and the results are shown in Table 1. The results are shown in Table 1. The results are shown in Table 1, Almost the same level.

Evaluation example  2

The surface cross-linking properties of the base resin of the superabsorbent resin were compared using the surface cross-linking agents obtained in Examples 1-4 and Comparative Examples 1, 3, 5, 7, 9 and 10, respectively. The base resin of K-SAM (manufactured by Kolon Chemical Industries, Ltd.) was used as the superabsorbent resin, and 100 g of the base resin was put in a high-speed mixer and pulverized. Thereafter, a surface crosslinked aqueous solution (0.03 g of surface crosslinking agent, distilled water 3.5 g and methanol 3.5 g) were added and stirred for 3 minutes. The base resin of the superabsorbent resin was spread evenly on the stainless steel tray, cured in a preheated 160 ° C oven for 30 minutes, cooled at room temperature, , A superabsorbent resin having a particle size of 200 to 600 탆 was prepared, and the physical properties of the superabsorbent resin after surface crosslinking and the pressure absorption capacity were shown in Table 2. Table 2 shows the results of using polypropylene glycol as a surface cross-linking agent for comparison with Examples 1-4 and Comparative Examples 1, 3, 5, 7, 9 and 10.

In the following Table 2, the crosslinking state was evaluated using a gelation tester, and the centrifugal retention capacity (CRC) was measured according to ED ANA method WSP 241.2 for the resins of the above Examples and Comparative Examples Respectively. That is, was impregnated with the Examples and Comparative Examples, the resin W (g) After (about 0.2g) and uniformly into sealing the bag of nonwoven fabric, normal saline at room temperature (0.9 wt. _^0/0) obtained through each. After about 30 minutes, water was drained from the envelope for 3 minutes under a condition of 250 G using a centrifuge, and the mass W2 (g) of the envelope was measured. In addition, after the same operation was performed without using a resin, the mass W1 (g) at that time was measured. Using the obtained masses, CRC (g / g) was calculated according to the following equation.

[Formula 1]

CRC (g / g) = {(W2 - W1) / (W - l)}

The pressure absorption capacity was in accordance with EDANA method WSP 242.2. Specifically, 0.9 g of a sample of 850 to 150 / m was uniformly distributed in a cylinder defined by the EDANA method, and then the piston was pressurized with a pressure of 21 g / cm ² , and then a 0.9 wt% brine solution was absorbed for 1 hour The amount was calculated and evaluated.

division Surface cross-linking reaction temperature (캜) Surface cross-linking reaction time (min) Bridging state
(sec) ^a Function
(g / g) Pressure absorption ability
(g / g) Example 1 160 30 124 32.4 21.7 Example 2 160 30 131 31.9 20.9 Example 3 160 30 137 31.5 21.0 Example 4 160 30 122 35.4 22.1 Comparative Example 1 180 60 160 ℃ Can not be measured 180 ℃ 327sec 28.4 19.3 Comparative Example 3 180 60 160 ℃ Can not be measured 180 ℃ 386sec 29.7 20.0 Comparative Example 5 180 60 160 ° C can not be measured
180 DEG C 401 sec 22.1 18.7 Comparative Example 7 180 60 160 ° C can not be measured
180 ° C 330sec 29.0 20.4 Comparative Example 9 180 60 160 ° C can not be measured
180 캜 379 sec 30.1 21.6 Comparative Example 10 160 30 185 25.4 20.8 Surface cross-linking agent Polypropylene glycol 200 90 160 ° C can not be measured
180 ℃ can not be measured
200 ° C 469 sec 29.3 20.1

a: Gelation Time measurement standard

The surface temperature of the gel timer was measured at 160 캜, 180 캜, and 200 캜, and the result of the gelation of the resin state with the elapse of time was measured.

As shown in Table 2, when the surface cross-linking agents of Examples 1 to 4 were used, the surface cross-linking reaction (curing reaction) rapidly proceeded at a lower temperature than in Comparative Examples 1, 3, 5, 7 and 9 In the case of polypropylene glycol, which is a conventional surface crosslinking agent, the temperature was 160 ° C for 30 minutes, As the curing condition, no surface hardening was observed and the results were obtained by calibrating at 200 ℃ for 90 minutes.

In the case of the cured physical properties, in the case of Examples 1, 2, 3 and 4, both the insulating performance and the pressure absorbing ability were superior to those of Comparative Examples 1, 3, 5, 7 and 9 and compared with the conventional surface crosslinking agent polypropylene glycol Good results were also obtained.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the scope of the present invention . Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (6)

A first step of mixing the polyhydric alcohol and the Lewis acid catalyst at 30 DEG C to 40 DEG C;
A second step of adding epichlorohydrin to the mixture of the first step and performing a reaction at 60 ° C to 90 ° C to obtain a halohydrin ether;
Adding a quaternary ammonium salt to the halohydrin ether obtained in the second step and reacting the quaternary ammonium salt at 50 ° C to 60 ° C;
A fourth step of adding a strong alkaline aqueous solution to the reaction product of the third step followed by a condensation reaction;
Separating the reaction product obtained in the fourth step from the salt layer and the resin layer containing epichlorohydrin using a dry filter at 40 ° C to 60 ° C;
A sixth step of recovering and removing excess epichlorohydrin from the result obtained by the fifth step; And
And a seventh step of adding an alkali adsorbent to the resultant obtained in the sixth step and mixing the resultant at 65 ° C to 80 ° C,
In the fourth step of performing the condensation reaction, a strong alkaline aqueous solution corresponding to 1/3 of the strong alkaline aqueous solution required for the reaction with the halohydrin ether is added to the reaction product obtained in the third step, and a solution A step; And a B step of adding a strong alkaline aqueous solution corresponding to 2/3 of the strong alkaline aqueous solution required for the reaction with the halohydrin ether to the reaction product obtained in the step A and further comprising a reduced pressure dehydration step, The reaction temperature is controlled to be increased as compared with the reaction temperature of the step A,
Wherein the reaction temperature in step A is 50 ° C to 60 ° C, the reaction temperature in step B is 60 ° C to 70 ° C, the quaternary ammonium salt is benzyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium hydroxide, Benzyltriethylammonium, and a combination thereof. The content of the quaternary ammonium salt is 0.5 to 20 parts by weight based on 100 parts by weight of the halohydrin ether,
Wherein the polyhydric alcohol is at least one selected from the group consisting of compounds represented by formulas (1a) to (1d), ethylene glycol, diethylene glycol and polyethylene glycol (Mw1000), the epichlorohydrin is represented by the following formula And aging the obtained halohydrin ether at 60 ° C to 90 ° C. The method of producing a low-temperature curable surface crosslinking agent of a superabsorbent resin,
[Chemical Formula 1a] [Chemical Formula 1b]

Wherein R ₁ is -H and R ₂ is -OH, R ₃ is -H, R ₄ is -OH,
[Chemical Formula 1c] [Chemical Formula 1d]

In the formula 1c, R ₅ is -H, R ₆ is -OH, and R ₇ is H, R ₈ is OH,
(2)

Wherein R ₉ is -OH or -Cl.









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