阅读说明：本技术 含有2-氰乙基的聚合物的制备方法 (Process for preparing 2-cyanoethyl group-containing polymers ) 是由 李镛满 黄闰泰 朴东薰 柳真英 于 2019-07-15 设计创作，主要内容包括：本公开涉及一种含有2-氰乙基的聚合物的制备方法,该制备方法即使在减少纯化过程中使用的水的量时,也可以制备具有高纯度的纯化的含有2-氰乙基的聚合物,并由此减少产生的废水的量。(The present disclosure relates to a method for preparing a 2-cyanoethyl group-containing polymer, which can prepare a purified 2-cyanoethyl group-containing polymer having high purity even when the amount of water used in a purification process is reduced, and thus reduce the amount of wastewater generated.)

1. A method for preparing a 2-cyanoethyl group-containing polymer, comprising the steps of:

reacting acrylonitrile with a hydroxyl containing compound to form a crude product comprising a polymer comprising 2-cyanoethyl groups; and

extracting the crude product with an extraction solvent comprising an organic solvent to form a purified 2-cyanoethyl group-containing polymer,

wherein the organic solvent has a Hansen solubility parameter distance of 6.8 or more with respect to the 2-cyanoethyl group-containing polymer,

wherein the organic solvent has a Hansen solubility parameter distance for acetone of 13.0 or less.

2. The method of preparing a 2-cyanoethyl group-containing polymer according to claim 1, wherein the organic solvent includes one or more selected from the group consisting of isopropanol, n-butanol, methanol, ethanol, toluene and methyl isobutyl ketone.

3. The method of preparing a 2-cyanoethyl group-containing polymer according to claim 1, wherein the extraction solvent is used in an amount of 80 to 500 parts by weight and the organic solvent is used in an amount of 20 to 100% by weight of the extraction solvent, based on 100 parts by weight of the crude product.

4. The method for preparing a 2-cyanoethyl group-containing polymer according to claim 1, wherein the extraction solvent comprises only the organic solvent or a mixed solvent of the organic solvent and water, and the extraction step is performed a plurality of times.

5. The method for preparing a polymer containing 2-cyanoethyl group according to claim 4, wherein the extraction solvent contains only the organic solvent, and the extraction step is performed two to five times.

6. The method for preparing a polymer containing 2-cyanoethyl group according to claim 4, wherein the extraction solvent comprises a mixed solvent of the organic solvent and water, and the extraction step is performed two to five times.

7. The method for producing a 2-cyanoethyl group-containing polymer according to any one of claims 4 to 6, wherein the extraction step further comprises extracting the crude product with water.

8. The method of preparing a 2-cyanoethyl group-containing polymer according to claim 1, wherein the step of reacting acrylonitrile with a hydroxyl group-containing compound is carried out under alkaline conditions in the presence of a catalyst comprising caustic soda (NaOH).

9. The method for producing a 2-cyanoethyl group-containing polymer according to claim 1, wherein the hydroxyl group-containing compound comprises a polyvinyl alcohol-based polymer, and the 2-cyanoethyl group-containing polymer is cyanoethyl polyvinyl alcohol.

10. The method of preparing a 2-cyanoethyl group-containing polymer according to claim 9, wherein the weight average molecular weight of the 2-cyanoethyl group-containing polymer is 100,000 to 600,000, and the substitution rate of the cyanoethyl group is 70% to 90%.

11. The method of claim 1, wherein the purified 2-cyanoethyl group-containing polymer contains less than 0.05 wt% acrylonitrile-containing by-products.

12. The method of claim 1, wherein the purified 2-cyanoethyl group-containing polymer comprises less than 0.05 wt% of Bis Cyanoethyl Ether (BCE) -containing by-products.

13. The method of claim 1, wherein the purified 2-cyanoethyl group-containing polymer comprises less than 10ppmw residual metal salt.

Technical Field

Cross Reference to Related Applications

This application claims the benefit of priority from korean patent application No. 10-2018-.

The present disclosure relates to a method for preparing a 2-cyanoethyl group-containing polymer, which can prepare a high-purity purified 2-cyanoethyl group-containing polymer even when the amount of water used in a purification process is reduced, and thus reduce the amount of wastewater generated.

Background

Recently, lithium secondary batteries have been applied to various applications/fields. In particular, as the capacity and energy density of lithium secondary batteries increase, there is an increasing interest in ensuring the heat resistance of separators.

In this regard, as a technique for preventing short circuits caused by thermal shrinkage or thermal melting of the separator and improving the reliability of the battery, a multilayer separator including a heat-resistant porous layer on one or both surfaces (i.e., front and back surfaces) of a porous substrate having pores, such as a polyethylene-based film, is proposed.

In such a separator, an inorganic material and a 2-cyanoethyl group-containing polymer as a dispersant for uniformly dispersing the inorganic material are widely used for the heat-resistant porous layer.

Such 2-cyanoethyl group-containing polymers can be generally prepared by reacting acrylonitrile with a hydroxyl group-containing compound such as polyvinyl alcohol under alkaline conditions using a catalyst comprising caustic soda (NaOH) or the like. In addition, as a reaction medium for carrying out these reactions, a solvent containing acetone is generally used. As the reaction proceeds, the hydroxyl groups may be substituted with cyanoethyl ether groups to produce 2-cyanoethyl group containing polymers such as cyanoethyl polyvinyl alcohol.

However, this reaction process inevitably produces unreacted materials acrylonitrile, residual metal salts from the catalyst and by-products such as dicyanoethyl ether (BCE), and these materials are contained in the crude product comprising the 2-cyanoethyl group-containing polymer.

Therefore, in order to remove unreacted materials, residual metal salts, by-products, and the like from the crude product comprising the 2-cyanoethyl group-containing polymer, after the reaction is completed, a method of extracting the 2-cyanoethyl group-containing polymer by a washing step using a large amount of water is applied. However, in this extraction process, not only a multi-step extraction process is required in order to sufficiently remove unreacted materials, residual metal salts, by-products, and the like, but also more than 50 times more water than the 2-cyanoethyl group-containing polymer needs to be used in the process. This is because the hydroxyl group-containing compound and the catalyst are used in the form of an aqueous solution at the time of substitution reaction, and therefore, a large amount of water is already contained in the crude product, and the 2-cyanoethyl group-containing polymer formed by the substitution reaction has a relatively low solid content concentration of about 5 to 10% by weight. Therefore, even in one extraction process, a large amount of water must be used for the precipitation/purification of the polymer.

Since a large amount of water is used in this manner, a large amount of harmful waste water (particularly, nitrogen-containing waste water) containing unreacted materials acrylonitrile, residual metal salts from the catalyst and by-products such as biscyanoethyl ether is inevitably produced after the extraction process is carried out, and very high process costs are required for purifying such waste water. Furthermore, since the extraction process is performed using water in multiple stages, there is a disadvantage in that process energy consumption is also very large.

Therefore, there is a need to develop a technology capable of obtaining a purified 2-cyanoethyl group-containing polymer with high purity while reducing the amount of water used in the purification/extraction process, thereby reducing the amount of wastewater generated.

Disclosure of Invention

Technical problem

The present disclosure provides a method for preparing a 2-cyanoethyl group-containing polymer, which can prepare a purified 2-cyanoethyl group-containing polymer having a high purity similar to the case of using a large amount of water even when the amount of water used in a purification process is reduced, and thus reduce the amount of wastewater generated.

Technical scheme

In one aspect of the present disclosure, there is provided a method for preparing a 2-cyanoethyl group-containing polymer, comprising the steps of:

reacting acrylonitrile with a hydroxyl containing compound to form a crude product comprising a polymer comprising 2-cyanoethyl groups; and

extracting the crude product with an extraction solvent comprising an organic solvent to form a purified 2-cyanoethyl group-containing polymer,

wherein the organic solvent has a Hansen solubility parameter distance (distance) of 6.8 or more with respect to the 2-cyanoethyl group-containing polymer,

wherein the organic solvent has a Hansen solubility parameter distance for acetone of 13.0 or less.

Hereinafter, a method for preparing a 2-cyanoethyl group-containing polymer according to a specific embodiment of the present disclosure will be described in more detail.

According to one embodiment of the present disclosure, there is provided a method for preparing a 2-cyanoethyl group-containing polymer, including the steps of:

reacting acrylonitrile with a hydroxyl containing compound to form a crude product comprising a polymer comprising 2-cyanoethyl groups; and

extracting the crude product with an extraction solvent comprising an organic solvent to form a purified 2-cyanoethyl group-containing polymer,

wherein the organic solvent has a Hansen solubility parameter distance of 6.8 or more with respect to the 2-cyanoethyl group-containing polymer,

wherein the organic solvent has a Hansen solubility parameter distance for acetone of 13.0 or less.

As a result of continuing experiments, the present inventors found that when an organic solvent satisfying a specific range of solubility parameter distance is used as an extraction solvent, a purified cyanoethyl group-containing polymer of high purity can be obtained even if water is not used in the extraction process or the amount of water used is greatly reduced, thereby completing the present disclosure.

As demonstrated in the examples below, it can be confirmed that, since an organic solvent is used as an extraction solvent, the unreacted materials acrylonitrile, residual metal salts from the catalyst and by-products such as dicyanoethyl ether can be effectively removed/purified from the crude product of the polymer, similarly to the conventional technique using a large amount of water.

This is expected because when the organic solvent containing the above-mentioned solubility parameter is sufficiently mixed with a solvent such as acetone used as a reaction medium, the solvent can serve as a non-solvent for the 2-cyanoethyl group-containing polymer. It was thus found that since only the unreacted materials, residual metal salts and/or by-products are selectively dissolved in the solvent used as the reaction medium without being mixed with the 2-cyanoethyl group-containing polymer, a high-purity 2-cyanoethyl group-containing polymer can be obtained in which the unreacted materials/residual metal salts/by-products are almost completely removed in the extraction process using such an organic solvent.

Therefore, in the existing extraction process, water can be completely or at least partially replaced with such an organic solvent, whereby, even when the amount of water generated in the extraction/purification process is reduced, it is possible to prepare a purified 2-cyanoethyl group-containing polymer having a high purity similar to that of the conventional art, and thereby reduce the amount of wastewater generated.

Hereinafter, the respective steps of the method for preparing a 2-cyanoethyl group-containing polymer according to one embodiment will be described.

In the production process of one embodiment, first, acrylonitrile is reacted with a hydroxyl group-containing compound to form a crude product comprising a polymer containing 2-cyanoethyl groups. This reaction step may be carried out according to a conventional method for preparing a 2-cyanoethyl group-containing polymer, which will be briefly described below.

In the above reaction step, the polymer can be produced by, for example, a Michael addition reaction between acrylonitrile and a hydroxyl group-containing compound (polymer) in the molecule, as shown in the following reaction scheme.

[ reaction scheme ]

In the above reaction scheme, polymer-OH represents a hydroxyl group-containing compound (polymer), polymer-O-CH₂-CH₂-CN represents a polymer containing 2-cyanoethyl groups.

More specifically, for example, the 2-cyanoethyl group-containing polymer can be prepared, for example, by dissolving a compound having a hydroxyl group in the molecule in water, adding a catalyst such as caustic soda and/or sodium carbonate, then adding acrylonitrile thereto and carrying out a reaction at about 0 ℃ to about 60 ℃ for about 2 hours to about 12 hours.

At this time, acrylonitrile may be added in an amount of 1 to 10 parts by weight or 5 to 10 parts by weight, based on 100 parts by weight of the hydroxyl group-containing compound.

In addition, acrylonitrile may also serve as a solvent in the above reaction step, but a diluting solvent such as acetone which does not react with acrylonitrile may be optionally added.

However, the present disclosure is not limited to the above reaction conditions, and specific reaction conditions such as temperature, time, and contents of reactants may be varied in adjusting the substitution rate of cyanoethyl groups.

Meanwhile, after a crude product comprising a 2-cyanoethyl group-containing polymer is formed by the above-mentioned reaction step, a step of extracting the crude product with an extraction solvent comprising an organic solvent is performed to form a purified 2-cyanoethyl group-containing polymer.

More specifically, after the above reaction is completed, the reaction solution is separated into two layers, an aqueous layer and an organic layer containing a polymer containing 2-cyanoethyl groups, and the organic layer is taken out and an extraction solvent is added thereto to precipitate a crude product, thereby obtaining a purified polymer containing 2-cyanoethyl groups.

In the production method of one embodiment, as the extraction solvent, a specific organic solvent having a hansen solubility parameter distance of 6.8 or more for a polymer containing 2-cyanoethyl groups and a hansen solubility parameter distance of 13.0 or less for acetone may be used.

In this case, the hansen solubility parameter can be defined and calculated as the solubility parameter distance (Ra, radius of hansen solubility sphere) of the organic solvent to the 2-cyanoethyl group-containing polymer or acetone. The calculation of the Hansen Solubility Parameters thus defined for the respective solvent, and the Hansen Solubility parameter distance for the 2-cyanoethyl-containing polymer or acetone is well known (see Hansen Solubility Parameters, a User's Handbook).

More specifically, the hansen solubility parameter distance can be calculated using the solubility parameter value for each solvent and the solubility parameter value for acetone and 2-cyanoethyl group-containing polymers according to equation 1 summarized in the manual:

[ equation 1]

Ra＝(4△D²+△P²+△H²)^1/2

Wherein the content of the first and second substances,

ra is the solubility parameter distance of the respective solvent for a polymer containing 2-cyanoethyl groups or acetone, defined as the solubility parameter distance,

Δ D is the distance (difference) of the dispersion (nonpolar) cohesion parameter of the solvent from the dispersion (nonpolar) cohesion parameter of the 2-cyanoethyl group-containing polymer or acetone,

Δ P is the distance (difference) between the dispersion cohesion parameter of the solvent and the polar cohesion parameter of the 2-cyanoethyl group-containing polymer or acetone,

Δ H is the distance (difference) between the polar cohesion parameter of the solvent and the polar cohesion parameter of the 2-cyanoethyl group-containing polymer or acetone,

specifically, the organic solvent used in the preparation method of one embodiment may have the following characteristics: the hansen solubility parameter distance for the 2-cyanoethyl group-containing polymer is 6.8 or more, or 7.0 or more, or 6.8 to 13.0, or 7.0 to 10.0. Thus, it exhibits immiscibility with a polymer containing 2-cyanoethyl groups and can be defined as a non-solvent therefor.

In addition, the organic solvent may have the following characteristics: the hansen solubility parameter distance for acetone is 13.0 or less, or 12.5 or less, or 2.0 to 12.5, or 5.0 to 12.5. This may indicate that the organic solvent is well mixed with the solvent used as the reaction medium, such as acetone.

Since the extraction step is performed using an organic solvent exhibiting these two characteristics, the organic solvent is not mixed with the 2-cyanoethyl group-containing polymer, and selectively dissolves only unreacted substances, residual metal salts and/or by-products in the solvent used as a reaction medium, thereby obtaining a high-purity 2-cyanoethyl group-containing polymer in which the unreacted substances/residual metal salts/by-products are almost completely removed during the extraction process.

Meanwhile, the above two characteristic values of the respective organic solvents are summarized in the following tables 1 and 2.

[ Table 1]

[ Table 2]

S.P.: hansen solubility parameter

Hsp (d): dispersion cohesion parameter

Hsp (p): polar cohesion parameter

HSP (H): hydrogen bond cohesion parameter

Ra: the solubility parameter distance of the respective solvent for the 2-cyanoethyl group-containing polymer is defined as the solubility parameter distance

Ra for acetone: hansen solubility parameter distance of organic solvent to acetone

In view of the respective characteristic values of tables 1 and 2, as the organic solvent in the extraction step, for example, one or more selected from the group consisting of isopropyl alcohol, n-butanol, methanol, ethanol, toluene, and methyl isobutyl ketone may be used. Among them, a suitable solvent may be selected and used in consideration of the type of the finally prepared 2-cyanoethyl group-containing polymer, the final substitution rate, and the like. However, among them, in view of immiscibility with a 2-cyanoethyl group-containing polymer, miscibility with a reaction medium such as acetone, and/or solubility of unreacted substances/residual metal salts/by-products, an alcohol solvent may be preferably used, and isopropanol may be most preferably used.

Meanwhile, the extraction solvent may be used in an amount of 80 to 500 parts by weight, or 100 to 400 parts by weight, or 150 to 300 parts by weight, based on 100 parts by weight of the crude product, based on a single extraction step. Thus, the efficiency of the extraction step can preferably be maintained without unduly increasing the amount of extraction solvent used.

In addition, the extraction solvent may contain only the above-mentioned organic solvent, or may contain other solvents such as water and organic solvents. In order to maintain extraction/purification efficiency according to a specific organic solvent, the organic solvent may be used in an amount of 20 to 100 wt%, or 50 to 100 wt%, or 70 to 100 wt% of the extraction solvent, and the balance of water and other solvents may be used as needed.

Meanwhile, in the above extraction step, the extraction solvent may contain only a specific organic solvent, but a mixed solvent of such an organic solvent and water may be used. The extraction step may be performed a plurality of times, for example, two to seven times, or two to five times.

In a specific example of the extraction method, the extraction solvent includes only an organic solvent, and the extraction step may be performed two to five times, or three to four times.

In another specific example of the extraction method, the extraction solvent includes a mixed solvent of an organic solvent and water, and the extraction step may be performed two to five times, or three to four times.

Further, in one specific example of the above extraction method, the extraction step may be performed only by a step of using an extraction solvent containing an organic solvent, but in addition thereto, a step of extracting with water may be performed once to three times.

Specific examples of such extraction methods may be appropriately selected in consideration of the specific type of the 2-cyanoethyl group-containing polymer, substitution rate, other process variables, and the like. In any of these methods, the amount of water used can be greatly reduced compared to existing processes, and thus, the amount of wastewater produced and the process cost/energy for treating the wastewater can be greatly reduced.

Meanwhile, examples of the 2-cyanoethyl group-containing polymer that can be prepared by the above process may be cyanoethyl polysaccharides such as cyanoethyl pullulan, cyanoethyl cellulose, cyanoethyl dihydroxypropyl pullulan, cyanoethyl hydroxyethyl cellulose, cyanoethyl hydroxypropyl cellulose, cyanoethyl starch, cyanoethyl polyvinyl alcohol, or the like. The type of the 2-cyanoethyl group-containing polymer may vary depending on the type of the hydroxyl group-containing compound, and cyanoethyl polyvinyl alcohol may be obtained by using a polyvinyl alcohol polymer as the hydroxyl group-containing compound.

In addition, the substitution rate of cyanoethyl groups in the 2-cyanoethyl group-containing polymer may be 70% to 90%, and the weight average molecular weight may be 100,000 to 600,000. Due to complicated factors such as the cyanoethyl substitution rate within the above range, and the molecular weight of the polymer, it can be suitably used as a dispersant in the separator.

Meanwhile, the substitution rate of cyanoethyl groups can be represented by the ratio (%) of the number of moles of hydroxyl groups substituted with cyanoethyl groups to the number of moles of hydroxyl groups present per monomer unit of the hydroxyl group-containing compound as a starting material.

Meanwhile, the substitution rate of cyanoethyl groups in the 2-cyanoethyl group-containing polymer is increased by preparing an aqueous solution of a hydroxyl group-containing compound such as polyvinyl alcohol in a process for preparing the 2-cyanoethyl group-containing polymer, and then adding an aqueous solution of a catalyst such as caustic soda. This substitution rate can be calculated based on the nitrogen content of the 2-cyanoethyl group-containing polymer measured by the Kjeldahl method.

The purified 2-cyanoethyl group-containing polymer prepared by the method of one embodiment may comprise less than 0.05 wt%, or 0.03 wt% or less, of Bis Cyanoethyl Ether (BCE) -containing by-products, based on the total weight of the polymer.

Additionally, the purified 2-cyanoethyl group-containing polymer may contain less than 10ppmw, or less than 5ppmw, of residual metal salts from catalysts and the like, based on the total weight of the polymer, and may contain the unreacted species acrylonitrile in an amount of less than 0.05 wt%, or less than 0.02 wt%.

Therefore, by applying the method of one embodiment, all or part of water in the extraction process is replaced with a specific organic solvent, whereby the amount of water used and the amount of waste water generated can be significantly reduced, and even with such reduced amount of water used, a high-purity purified 2-cyanoethyl group-containing polymer can be obtained. Such a high-purity 2-cyanoethyl group-containing polymer can be very preferably used as a dispersant for a separator for a lithium secondary battery or the like.

Advantageous effects

As described above, since the present disclosure uses an extraction solvent including a specific organic solvent, there is provided a method for preparing a 2-cyanoethyl group-containing polymer, which can prepare a purified 2-cyanoethyl group-containing polymer of high purity similar to the case of using a large amount of water even when the amount of water used in a purification process is reduced, and thus reduce the amount of wastewater generated.

Detailed Description

Hereinafter, the present disclosure will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only, and the present invention is not intended to be limited by these examples.

The substitution rate of cyanoethyl groups was calculated from the ratio of the number of moles of hydroxyl groups originally present per repeating unit of the polymer after determining the nitrogen content of cyanoethylated polyvinyl alcohol prepared in the following synthetic examples by the kyerdall method.

The weight average molecular weight value was analyzed by GPC, and the measurement conditions of GPC are as follows.

The device comprises the following steps: gel permeation chromatography GPC (measuring instrument name: Alliance e 2695; manufacturer: WATERS)

A detector: differential refractive index detector (measuring instrument name: W2414; manufacturer: WATERS)

Column: DMF column

Flow rate: 1mL/min

Column temperature: 65 deg.C

Sample introduction volume: 0.100mL

And (3) standard substance: polystyrene

Synthesis example 1

1 part by weight of polyvinyl alcohol (PVA), 6 parts by weight of Acrylonitrile (AN), and 1.32 parts by weight of a 1 wt% aqueous solution of caustic soda were added to a reactor equipped with a stirrer, and reacted at 50 ℃ for 100 minutes. To this were added 10 parts by weight of acetone and 3 parts by weight of water, the mixture was stirred for 40 minutes, and then 0.088 part by weight of a 25% by weight aqueous acetic acid solution was added to terminate the reaction.

(substitution rate of cyanoethyl group: 79%, MW: 408K)

Synthesis example 2

1 part by weight of a 20 wt% aqueous polyvinyl alcohol (PVA) solution, 0.02 part by weight of a 30 wt% aqueous caustic soda solution, and 1.5 parts by weight of Acrylonitrile (AN) were charged into a reactor equipped with a stirrer, and reacted at 50 ℃ for 50 minutes. To this was added 5 parts by weight of acetone, followed by stirring for 50 minutes, followed by further addition of acetic acid to terminate the reaction.