Title of the invention: Method for producing 2-cyanoethyl group-containing polymer
Technical field
[One]
Cross-reference with related application(s)
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0085442 filed July 23, 2018 and Korean Patent Application No. 10-2019-0084310 filed July 12, 2019. All contents disclosed in the literature are included as part of this specification.
[3]
The present invention relates to a method for producing a 2-cyanoethyl group-containing polymer capable of producing a highly purified 2-cyanoethyl group-containing polymer while reducing the amount of wastewater generated by reducing the amount of water used during the purification process.
Background
[4]
Recently, lithium secondary batteries have been applied to various uses/fields. In particular, as lithium secondary batteries become larger in capacity and higher energy density, interest in securing heat resistance of the separator is increasing.
[5]
This is a technology that increases the reliability of the battery by preventing the separator from shorting due to heat shrinkage or heat melting. A separator having a multi-layered structure has been proposed.
[6]
In such a separator, as the heat-resistant porous layer, a 2-cyanoethyl group-containing polymer is widely used as a dispersant for evenly dispersing the inorganic material and the inorganic material.
[7]
Such a 2-cyanoethyl group-containing polymer can be prepared by reacting a hydroxyl group-containing compound such as acrylonitrile and polyvinyl alcohol under basic conditions in which a catalyst including caustic soda (NaOH) or the like is typically used. In addition, a solvent including acetone is typically used as a reaction medium for proceeding the reaction. As the reaction proceeds, a hydroxyl group is substituted with a cyanoethyl ether group to prepare a 2-cyanoethyl group-containing polymer such as cyanoethylpolyvinyl alcohol.
[8]
However, in this reaction process, inevitably, unreacted products of acrylonitrile, residual metal salts derived from catalysts, and by-products such as bis-cyanoethyl ether (BCE) may be generated. -Included in crude products containing cyanoethyl group-containing polymers.
[9]
Accordingly, in order to remove unreacted products, residual metal salts and by-products from the crude product including the 2-cyanoethyl group-containing polymer, the 2-cyanoethyl group-containing polymer was extracted by washing with a large amount of water after the reaction was completed. The method was applied. However, in this extraction process, in order to sufficiently remove the unreacted products, residual metal salts and by-products, a multi-step extraction process is required, and in the process, water is used 50 times more than the 2-cyanoethyl group-containing polymer. to be.
[10]
This is because during the substitution reaction, the hydroxyl group-containing compound and the catalyst are used in an aqueous solution state, so a large amount of water is already included in the crude product, and the solid content concentration of the 2-cyanoethyl group-containing polymer formed by the substitution reaction is 5 to 10 This is because it is relatively low, about weight percent. For this reason, even in a single extraction process, a large amount of water is inevitably used for precipitation/purification of the polymer.
[11]
As a result of the use of such a large amount of water, after the extraction process proceeds, the unreacted product of the acrylonitrile, the residual metal salt derived from the catalyst, and the malignant wastewater including by-products such as bis-cyanoethyl ether (especially nitrogen-containing Wastewater, etc.) is inevitably generated in large quantities, and a very large process cost is being required to purify such wastewater. Moreover, due to the extraction process using the multi-stage water, there is a disadvantage in that process energy consumption is also very large.
[12]
Accordingly, there is a demand for the development of a technology capable of obtaining a highly purified 2-cyanoethyl group-containing polymer while reducing the amount of wastewater generated by reducing the amount of water used during the purification/extraction process.
Detailed description of the invention
Technical challenge
[13]
Accordingly, the present invention provides a 2-cyanoethyl group-containing polymer capable of producing a highly purified 2-cyanoethyl group-containing polymer in accordance with the case of using a large amount of water while reducing the amount of wastewater generated by reducing the amount of water used during the purification process. It is to provide a manufacturing method.
Means of solving the task
[14]
The present invention comprises the steps of reacting acrylonitrile and a hydroxyl group-containing compound to form a crude product containing a 2-cyanoethyl group-containing polymer; And
[15]
Extracting the crude product with an extraction solvent including an organic solvent to form a purified 2-cyanoethyl group-containing polymer,
[16]
The organic solvent has a Hansen solubility parameter distance of 6.8 or more for the 2-cyanoethyl group-containing polymer,
[17]
The organic solvent provides a method for producing a 2-cyanoethyl group-containing polymer having a Hansen solubility parameter distance of 13.0 or less in acetone.
[18]
Hereinafter, a method for preparing a 2-cyanoethyl group-containing polymer according to a specific embodiment of the present invention will be described in more detail.
[19]
According to an embodiment of the present invention, by reacting an acrylonitrile and a hydroxyl group-containing compound to form a crude product including a 2-cyanoethyl group-containing polymer; And
[20]
Extracting the crude product with an extraction solvent including an organic solvent to form a purified 2-cyanoethyl group-containing polymer,
[21]
The organic solvent has a Hansen solubility parameter distance of 6.8 or more for the 2-cyanoethyl group-containing polymer,
[22]
The organic solvent is provided with a method for producing a 2-cyanoethyl group-containing polymer in which the Hansen solubility parameter distance in acetone is 13.0 or less.
[23]
As a result of continuous experiments of the present inventors, as an organic solvent that satisfies a certain range of solubility parameter distances was used as the extraction solvent, water was not used in the extraction process, or water was greatly reduced in amount of water, and purified 2- It was confirmed that a cyanoethyl group-containing polymer could be obtained, and the invention was completed.
[24]
As evidenced by the following examples, as a result of using the organic solvent as an extraction solvent, in accordance with the prior art using a large amount of water, the unreacted product of the acrylonitrile, residual metal salt derived from a catalyst, etc., and bis -It was confirmed that by-products such as cyanoethyl ether can be effectively removed/purified from the crude product of the polymer.
[25]
This is predicted because the organic solvents including the solubility parameter are well mixed with the solvent used as a reaction medium such as acetone, but can act as a non-solvent for the 2-cyanoethyl group-containing polymer. As a result, the unreacted product is not mixed with the 2-cyanoethyl group-containing polymer, and only the unreacted product, residual metal salt, and/or by-product, etc. in the solvent used as the reaction medium is selectively dissolved. It was confirmed that a high-purity 2-cyanoethyl group-containing polymer in which /residual metal salts/by-products were almost completely removed could be obtained.
[26]
Therefore, by completely replacing or at least partially replacing water in the existing extraction process with such an organic solvent, the amount of wastewater generated by reducing the amount of water used during the extraction/purification process is reduced, while the 2-cyanoethyl group purified with high purity according to the prior art The containing polymer can be prepared.
[27]
Hereinafter, a method for preparing a 2-cyanoethyl group-containing polymer according to an embodiment will be described in each step.
[28]
In the production method of one embodiment, first, acrylonitrile and a hydroxyl group-containing compound are reacted to form a crude product including a 2-cyanoethyl group-containing polymer. This reaction step can be followed by a conventional method for producing a 2-cyanoethyl group-containing polymer, which will be briefly described below.
[29]
Such a reaction step may be prepared by Michael addition reaction of acrylonitrile and a compound (polymer) containing a hydroxyl group in the molecule as indicated by the following reaction scheme, for example.
[30]
[Reaction Scheme]
[31]

[32]
In the above reaction formula, Polym-OH represents a hydroxyl group-containing compound (polymer), and Polym-O-CH 2 -CH 2 -CN represents a 2-cyanoethyl group-containing polymer.
[33]
More specifically, in the 2-cyanoethyl group-containing polymer, for example, a compound having a hydroxyl group in the molecule is dissolved in water, a catalyst such as caustic soda and/or sodium carbonate is added, followed by the addition of acrylonitrile. And, it can be prepared by performing the reaction at about 0 to about 60 ℃ about 2 to about 12 hours.
[34]
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 1 part by weight of the hydroxyl group-containing compound.
[35]
In addition, in the above reaction step, acrylonitrile may also serve as a solvent, and a dilute solvent that does not react with acrylonitrile, such as acetone, may be further added.
[36]
However, the invention is not limited to the reaction conditions described above, and specific reaction conditions such as temperature, time, and content of reactants may vary in terms of controlling the substitution ratio of the cyanoethyl group.
[37]
On the other hand, after forming a crude product containing a 2-cyanoethyl group-containing polymer through the above-described reaction step, the crude product is extracted with an extraction solvent containing an organic solvent to form a purified 2-cyanoethyl group-containing polymer. Go through the steps.
[38]
More specifically, after the above reaction is completed, the reaction solution is separated into two layers of an aqueous layer and an organic layer containing a 2-cyanoethyl group-containing polymer. The organic layer is taken out, and the above extraction solvent is added thereto to precipitate a crude product, A purified 2-cyanoethyl group-containing polymer can be obtained.
[39]
In the method of one embodiment, a specific organic solvent in which the Hansen solubility parameter distance for the 2-cyanoethyl group-containing polymer is 6.8 or more and the Hansen solubility parameter distance for acetone is 13.0 or less may be used as the extraction solvent.
[40]
At this time, the Hansen solubility parameter can be defined and calculated as a solubility parameter distance (Ra, radious of the Hansen Solubility Sphere) for a polymer or acetone containing a 2-cyanoethyl group of the organic solvent, and for each solvent defined in this way The method of calculating the Hansen solubility parameter and the Hansen solubility parameter distance for a 2-cyanoethyl group-containing polymer or acetone therefrom has been well known from the past (see HANSEN SOLUBILITY PARAMETERS, A User's Handbook).
[41]
More specifically, the Hansen solubility parameter distance can be calculated according to Equation 1 below, using the solubility parameter values ​​for each solvent and the solubility parameter values ​​of acetone and 2-cyanoethyl group-containing polymers summarized in this handbook:
[42]
[Equation 1]
[43]
Ra = (4△D 2 +△P 2 +△H 2 ) 1/2
[44]
In the above formula, Ra: is the Hansen solubility parameter distance of each solvent to a polymer or acetone containing a 2-cyanoethyl group defined as the solubility parameter distance,
[45]
ΔD is the distance (difference value) between the non-polar solubility parameter in the solvent and the non-polar solubility parameter in the 2-cyanoethyl group-containing polymer or acetone,
[46]
ΔP is the distance (difference value) between the polar cohesion parameter in the solvent and the polar solubility parameter in the 2-cyanoethyl group-containing polymer or acetone,
[47]
ΔH is the distance (difference value) between the hydrogen bonding cohesion parameter in the solvent and the hydrogen bonding solubility parameter in the 2-cyanoethyl group-containing polymer or acetone.
[48]
In particular, the organic solvent used in the method of one embodiment may have a characteristic of a Hansen solubility parameter distance of 6.8 or more, or 7.0 or more, or 6.8 to 13.0 or 7.0 to 10.0 for the 2-cyanoethyl group-containing polymer. As a result, it can be defined as a non-solvent (NON-SOLVENT) for it exhibits immiscibility with the 2-cyanoethyl group-containing polymer.
[49]
In addition, the organic solvent may have a Hansen solubility parameter distance for the acetone of 13.0 or less, or 12.5 or less, or 2.0 to 12.5 or 5.0 to 12.5. This may mean that the organic solvents are well mixed with the solvent used as a reaction medium such as acetone.
[50]
As the extraction process proceeds using an organic solvent exhibiting these two characteristics, the organic solvent is not mixed with the 2-cyanoethyl group-containing polymer, and unreacted products, residual metal salts and/or by-products in the solvent used as the reaction medium. By selectively dissolving the bay, it is possible to obtain a high-purity 2-cyanoethyl group-containing polymer in which the unreacted product/residual metal salt/by-product is almost completely removed during the extraction process.
[51]
Meanwhile, for various organic solvents, the two characteristic values ​​are summarized in Tables 1 and 2 below.
[52]
[Table 1]
[53]
[Table 2]
[54]
SP: Hansen Solubility parameter
[55]
HSP(D): Dispersion cohesion parameter
[56]
HSP(P): Polar cohesion parameter
[57]
HSP(H): Hydrogen bonding cohesion parameter
[58]
Ra: Hansen solubility parameter distance of each solvent for the 2-cyanoethyl group-containing polymer defined as the solubility parameter distance
[59]
Ra from Ace: Hansen solubility parameter distance in acetone of the organic solvent
[60]
In consideration of the respective characteristic values ​​of Tables 1 and 2, the organic solvent in the extraction step is, for example, selected from the group consisting of isopropyl alcohol, n-butanol, methanol, ethanol, toluene, and methyl isobutyl ketone. More than one type can be used. Among these, an appropriate solvent may be selected and used in consideration of the type of the 2-cyanoethyl group-containing polymer to be finally prepared, the substitution rate, and the like. However, among these, alcohol-based solvents can be preferably used in consideration of immiscibility with a 2-cyanoethyl group-containing polymer, miscibility with a reaction medium such as acetone, and/or solubility of unreacted products/remaining metal salts/by-products. And, isopropyl alcohol can be most preferably used.
[61]
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. As a result, the efficiency of the extraction step can be preferably maintained without excessively increasing the amount of the extraction solvent used.
[62]
In addition, the extraction solvent may include only the organic solvent described above, or may include other solvents such as water together with the organic solvent. In order to maintain the extraction/purification efficiency according to the specific organic solvent, the organic solvent is It is used in an amount of 20 to 100% by weight, or 50 to 100% by weight, or 70 to 100% by weight of the extraction solvent, and optionally a residual amount of water and other solvents may be used.
[63]
Meanwhile, in the above extraction step, the extraction solvent may include only the specific organic solvent described above, but a mixed solvent of such an organic solvent and water may be used, and the extraction step may be performed multiple times, for example, 2 to 7 times. , Or it may proceed to 2 to 5 times.
[64]
In a specific example of such an extraction method, the extraction solvent alone includes the organic solvent, and the extraction step may be performed 2 to 5 times, or 3 to 4 times.
[65]
Further, in another specific example of the extraction method, the extraction solvent includes a mixed solvent of the organic solvent and water, and the extraction step may be performed 2 to 5 times, or 3 to 4 times.
[66]
And, in specific examples of the above-described extraction method, the extraction step may be performed only as a step using an extraction solvent including the organic solvent, but in addition, the step of extracting with water may be additionally performed once to three times.
[67]
Specific examples of such an extraction method may be appropriately selected in consideration of a specific type of a 2-cyanoethyl group-containing polymer, a substitution rate, or other process variables. By any of these methods, it is possible to significantly reduce the amount of water used compared to the existing process, and accordingly, it is possible to greatly reduce the amount of wastewater generated and the process cost/energy for treatment thereof.
[68]
Meanwhile, examples of the 2-cyanoethyl group-containing polymer that can be produced through the above-described process include cyanoethyl pullulan, cyanoethyl cellulose, cyanoethyldihydroxypropyl pullulan, cyanoethylhydroxyethylcellulose, and cyanoethylhydroxyethylcellulose. Cyanoethyl polysaccharides such as noethylhydroxypropyl cellulose and cyanoethyl starch, cyanoethylpolyvinyl alcohol, etc. may be used, and cyanoethylpolyvinyl alcohol may be suitably used. The type of the 2-cyanoethyl group-containing polymer may vary depending on the type of the hydroxyl group-containing compound, and the cyanoethylpolyvinyl alcohol may be obtained by using a polyvinyl alcohol-based polymer as the hydroxyl group-containing compound.
[69]
Further, the cyanoethyl group substitution ratio of the 2-cyanoethyl group-containing polymer may be 70 to 90%, and the weight average molecular weight may be 100,000 to 600,000. It can be suitably used as a dispersing agent in the separator due to complex factors such as the cyanoethyl group substitution rate in the above range and the molecular weight of the polymer.
[70]
Meanwhile, the cyanoethyl group substitution rate may be expressed as a ratio (%) of the number of moles of hydroxyl groups substituted with a cyanoethyl group to the number of moles of hydroxyl groups present per monomer unit of the hydroxyl group-containing compound as a starting material.
[71]
On the other hand, the cyanoethyl group substitution rate of the 2-cyanoethyl group-containing polymer is determined by preparing an aqueous solution of a hydroxyl group-containing compound such as polyvinyl alcohol, and then adding a catalyst aqueous solution such as caustic soda in the production process of the 2-cyanoethyl group-containing polymer. It is improved by doing. Such a substitution rate can be calculated from the nitrogen content of the 2-cyanoethyl group-containing polymer measured by the Kjeldahl method.
[72]
The purified 2-cyanoethyl group-containing polymer prepared by the method of the above-described embodiment contains less than 0.05% by weight, or 0.03% by weight of a by-product including bis-cyanoethyl ether (BCE), based on the total weight of the polymer. It may be included in the following content.
[73]
In addition, the purified 2-cyanoethyl group-containing polymer may contain less than 10 ppmw or less than 5 ppmw of residual metal salts derived from catalysts based on its total weight, and less than 0.05% by weight of unreacted products including acrylonitrile. , Or may contain less than 0.02% by weight.
[74]
As described above, by applying the method of one embodiment, by replacing all or part of the water in the extraction process with a specific organic solvent, it is possible to greatly reduce the amount of water used and the amount of wastewater generated, and even with such a reduced amount of water, A 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 of a lithium secondary battery or the like.
Effects of the Invention
[75]
As described above, according to the present invention, as the extraction solvent containing a specific organic solvent is used, the amount of wastewater is reduced by reducing the amount of water used during the purification process, while 2-cyano purified with high purity according to the case of using a large amount of water. It provides a method for producing a 2-cyanoethyl group-containing polymer capable of producing an ethyl group-containing polymer.
Mode for carrying out the invention
[76]
The invention will be described in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.
[77]
The cyanoethyl substitution rate was calculated as a% ratio of the number of moles of hydroxyl groups originally present per repeating unit of the polymer after obtaining the nitrogen content through the Kjeldahl Method for the cyanoethylated polyvinyl alcohol produced in the following Synthesis Example.
[78]
The weight average molecular weight value was analyzed through GPC, and the measurement conditions of GPC are as follows.
[79]
Apparatus: Gel permeation chromatography GPC (measurement instrument name: Alliance e2695; manufacturer: WATERS)
[80]
Detector: differential refractive index detector (measurement device name: W2414; manufacturer: WATERS)
[81]
Column: DMF column
[82]
Flow rate: 1 mL/min
[83]
Column temperature: 65°C
[84]
Injection volume: 0.100 mL
[85]
Sample for standardization: polystyrene
[86]
Synthesis Example 1
[87]
1 part by weight of polyvinyl alcohol (PVA), 6 parts by weight of Acrylonitrile (AN), and 1.32 parts by weight of an aqueous solution of 1 wt% caustic soda were added to a reactor equipped with a stirrer and reacted at 50° C. for 100 minutes. 10 parts by weight of acetone and 3 parts by weight of water were added thereto, and after stirring for 40 minutes, 0.088 parts by weight of an aqueous solution of 25 wt% acetic acid was added to terminate the reaction.
[88]
(Cyanoethyl substitution rate: 79%, MW: 408K)
[89]
Synthesis Example 2
[90]
1 part by weight of a 20% by weight aqueous solution of polyvinyl alcohol (PVA), 0.02 part by weight of a 30% by weight aqueous solution of caustic soda, and 1.5 parts by weight of Acrylonitrile (AN) were added to a reactor equipped with a stirrer and reacted at 50° C. for 50 minutes. After adding 5 parts by weight of acetone and stirring for 50 minutes, acetic acid was added thereto to terminate the reaction.
[91]
Examples 1 to 4
[92]
Organic solvent (the types of solvents used in each example are summarized in Table 3 below.) To a reaction tank containing 150 parts by weight, 100 parts by weight of the crude product of the 2-cyanoethyl group-containing polymer obtained in Synthesis Example 1 was added to 2 -A cyanoethyl group-containing polymer (cyanoethylpolyvinyl alcohol) was deposited. After the precipitated polymer was redissolved in 30 parts by weight of acetone, the organic solvent precipitation process was performed once more. After extraction twice, the polymer dissolved in acetone was added to a reaction tank containing 150 parts by weight of water and re-precipitated. After that, a purified polymer was obtained through a drying process.
[93]
Comparative Example 1
[94]
100 parts by weight of the crude product of the 2-cyanoethyl group-containing polymer obtained in Synthesis Example 1 was added to a reaction tank containing 500 parts by weight of water to precipitate a 2-cyanoethyl group-containing polymer (cyanoethylpolyvinyl alcohol). Subsequent steps were carried out in the same manner as in Examples 1 to 4 to obtain a purified polymer.
[95]
In Examples 1 to 4 and Comparative Example 1, the content of residual unreacted material (AN) and by-product (Bis-cyanoethyl ether, BCE) in each obtained polymer precipitated after the first extraction step was analyzed/confirmed by gas chromatography, The residual metal salt content was analyzed/confirmed using an ICP mass spectrometer.
[96]
More specifically, the residual unreacted products and by-products were analyzed using GC-FID (manufacturer Agilent) after diluting the polymer in DMF, and the residual metal salt content in the extracted product was ICP-OES (measurement instrument name Optima 8300; manufacturer Perkinelmer) ) It was measured using an analysis equipment. These analysis/confirmation results are summarized in Table 3 below:
[97]
[Table 3]
[98]
Referring to Table 3, it was confirmed that in Examples 1 to 4, by performing the first extraction process with a specific organic solvent, the content of by-products/unreacted materials can be further reduced compared to extraction with water.
[99]
Example 5
[100]
A 2-cyanoethyl group-containing polymer (cyanoethylpolyvinyl alcohol) by adding 100 parts by weight of the crude product of the 2-cyanoethyl group-containing polymer obtained in Synthesis Example 2 to a reaction tank containing 100 parts by weight of isopropyl alcohol solvent and 300 parts by weight of water Was precipitated. After re-dissolving the precipitated polymer in 30 parts by weight of acetone, the extraction process using the isopropyl alcohol/water mixed solvent and the process of re-dissolving acetone were repeated two more times. After that, a purified polymer was obtained through a drying process.
[101]
Comparative Example 2
[102]
100 parts by weight of the crude product of the 2-cyanoethyl group-containing polymer obtained in Synthesis Example 2 was added to a reaction tank containing 500 parts by weight of water to precipitate a 2-cyanoethyl group-containing polymer (cyanoethylpolyvinyl alcohol). After re-dissolving the precipitated polymer in 30 parts by weight of acetone, the extraction process using the water and the process of re-dissolving acetone were repeated 5 times. After that, a purified polymer was obtained through a drying process.
[103]
The polymers finally obtained after the third extraction using isopropyl alcohol and water in Example 5, and residual unreacted products (AN) and by-products (Bis-cyanoethyl ether, BCE) in the polymers obtained in Examples 4 and 2, respectively. The content was analyzed/confirmed by gas chromatography, and the residual metal salt content was analyzed/confirmed using an ICP mass spectrometer. Gas chromatography and ICP analysis apparatus/method were applied in the same manner as in Examples 1 to 4 described above.
[104]
The analysis/confirmation results and the amount of solvent (water) used in Examples/Comparative Examples are summarized in Table 4 below:
[105]
[Table 4]
[106]
Referring to Table 4, it was confirmed that, in Examples 4 and 5, a highly purified 2-cyanoethyl group-containing polymer could be obtained by reducing the content of by-products/unreacted products/residual metal salts according to Comparative Example 2. Furthermore, it was confirmed that in the examples, the amount of water used (wastewater generation amount) can be significantly reduced compared to the comparative examples.
Claims
[Claim 1]
Reacting an acrylonitrile and a hydroxyl group-containing compound to form a crude product including a 2-cyanoethyl group-containing polymer; And extracting the crude product with an extraction solvent including an organic solvent to form a purified 2-cyanoethyl group-containing polymer, wherein the organic solvent has a Hansen solubility parameter distance for the 2-cyanoethyl group-containing polymer 6.8 or more, wherein the organic solvent has a Hansen solubility parameter distance in acetone of 13.0 or less.
[Claim 2]
The method of claim 1, wherein the organic solvent comprises at least one selected from the group consisting of isopropyl alcohol, n-butanol, methanol, ethanol, toluene, and methyl isobutyl ketone.
[Claim 3]
The method of claim 1, wherein the extraction solvent is used in an amount of 80 to 500 parts by weight based on 100 parts by weight of the crude product, and the organic solvent is used in an amount of 20 to 100% by weight of the extraction solvent. Method for producing a noethyl group-containing polymer.
[Claim 4]
The method of claim 1, wherein the extraction solvent comprises the organic solvent alone or a mixed solvent of the organic solvent and water, and the extraction step is performed multiple times.
[Claim 5]
The method of claim 4, wherein the extraction solvent comprises the organic solvent alone, and the extraction step is performed two to five times.
[Claim 6]
The method of claim 4, wherein the extraction solvent comprises a mixed solvent of the organic solvent and water, and the extraction step is performed 2 to 5 times.
[Claim 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.
[Claim 8]
The method of claim 1, wherein the reaction step of the acrylonitrile and the hydroxyl group-containing compound is performed under basic conditions in the presence of a catalyst including caustic soda (NaOH).
[Claim 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 cyanoethylpolyvinyl alcohol.
[Claim 10]
The method for producing a 2-cyanoethyl group-containing polymer according to claim 9, wherein the 2-cyanoethyl group-containing polymer has a weight average molecular weight of 100,000 to 600,000 and a cyanoethyl group substitution ratio of 70 to 90%.
[Claim 11]
The method of claim 1, wherein the purified 2-cyanoethyl group-containing polymer contains less than 0.05% by weight of an unreacted product including acrylonitrile.
[Claim 12]
The method of claim 1, wherein the purified 2-cyanoethyl group-containing polymer contains less than 0.05% by weight of a by-product including bis-cyanoethyl ether (BCE).
[Claim 13]
The method of claim 1, wherein the purified 2-cyanoethyl group-containing polymer contains a residual metal salt of less than 10 ppmw.