Cyanoethyl group-containing polymer and preparation method thereof

Abstract

A cyanoethyl group-containing polymer and a preparation method thereof are provided. The cyanoethyl group-containing polymer is characterized by having very low contents of functional groups other than cyanoethyl groups.

Claims

1. A method of preparing a cyanoethyl group-containing polymer, the method comprising mixing a reactive functional group-containing polymer, a cyanoethyl group-introducing precursor, a basic catalyst, and a first solvent to prepare a mixture, and during a cyanoethylation of the mixture, adding a second solvent so that Ra calculated by the following Equation 1 is less than 6:
(Ra).sup.2=4(δ.sub.D2−δ.sub.D1).sup.2+(δ.sub.P2−δ.sub.P1).sup.2+(δ.sub.H2−δ.sub.H1).sup.2  [Equation 1] in Equation 1, δ.sub.D2, δ.sub.P2, and δ.sub.H2 represent a solubility parameter due to a dispersion force, a solubility parameter due to a dipolar intermolecular force, and a solubility parameter due to hydrogen bonding of a mixture obtained by mixing the reactive functional group-containing polymer and the cyanoethyl group-introducing precursor at a molar ratio of 100-x:x, respectively, and x represents a ratio of replacement by a cyanoethyl groups, which is measured at any one point, and δ.sub.D1, δ.sub.P1, and δ.sub.H1 represent a solubility parameter due to a dispersion force, a solubility parameter due to a dipolar intermolecular force, and a solubility parameter due to hydrogen bonding of a solvent system which is used in the cyanoethylation at any one point, respectively, wherein the cyanoethyl group-containing polymer comprises 1.0% or less of a repeating unit including —OCH.sub.2CH.sub.2CONH.sub.2 and ions thereof and 2.0% or less of a repeating unit including —OCH.sub.2CH.sub.2COOH and ions thereof, with respect to total repeating units included in the cyanoethyl group-containing polymer.

2. The method of claim 1, wherein the cyanoethylation is performed at a temperature of 10° C. to 60° C. for 40 minutes to 500 minutes.

3. The method of claim 1, wherein the cyanoethyl group-containing polymer is polyvinyl alcohol, and the cyanoethyl group-introducing precursor is acrylonitrile.

4. The method of claim 1, wherein an alcohol solvent, a ketone solvent, a sulfoxide solvent, or a mixed solvent thereof is added as the second solvent.

5. The method of claim 1, wherein the second solvent is added two or more times within the range of 25% to 85% of the ratio of replacement by a cyanoethyl groups.

6. The method of claim 1, wherein the second solvent is added in an amount of 30 parts by weight to 70 parts by weight with respect to 100 parts by weight of the first solvent within the range of 25% to 35% of the ratio of replacement by a cyanoethyl groups, and the second solvent is added in an amount of 30 parts by weight to 130 parts by weight with respect to 100 parts by weight of the first solvent within the range of 45% to 55% of the ratio of replacement by a cyanoethyl groups.

7. The method of claim 3, wherein the cyanoethyl group-containing polymer comprises 1.0% or less of a repeating unit represented by the following Chemical Formula 3 and 2.0% or less of a repeating unit represented by the following Chemical Formula 4, with respect to a total amount of repeating units represented by the following Chemical Formulae 1 to 4: ##STR00004## in Chemical Formulae 3 and 4, m is an integer of 1 to 3, and n is 0 or 1.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) Hereinafter, actions and effects of the present invention will be described in more detail with reference to specific examples of the present invention. However, these examples are for illustrative purposes only, and the scope of the present invention is not intended to be limited by these examples.

EXAMPLE 1

Preparation of Cyanoethyl Group-Containing Polymer

(2) 100 g of a 20% by weight polyvinyl alcohol aqueous solution (20 g of polyvinyl alcohol, 80 g of distilled water), 2 g of a 30% by weight NaOH aqueous solution (0.6 g of NaOH, 1.4 g of distilled water), and 150 g of acrylonitrile were added to a reaction vessel, and stirred at 30° C. to allow cyanoethylation.

(3) A ratio of replacement by cyanoethyl groups was monitored through H-NMR, and when the ratio of replacement by cyanoethyl groups was 30%, 30 g of acetone was added to the reaction vessel.

(4) Referring to Table 1, it was confirmed that when the ratio of replacement by cyanoethyl groups was 30%, δ.sub.D2, δ.sub.P2, and δ.sub.H2 of Equation 1 were 15.93 MPa.sup.1/2, 9.51 MPa.sup.1/2, and 15.20 MPa.sup.1/2, respectively. Meanwhile, when the ratio of replacement by cyanoethyl groups was 30%, acetone was added, and at this time, δ.sub.D1, δ.sub.P1, and δ.sub.H1 of Equation 1 were 15.78 MPa.sup.1/2, 13.54 MPa.sup.1/2, and 18.19 MPa.sup.1/2, respectively. When these solubility parameters were put into Equation 1, it was confirmed that Ra was 5.03 and less than 6 at 30% of the ratio of replacement by cyanoethyl groups.

(5) When the ratio of replacement by cyanoethyl groups reached 50% by continuing the cyanoethylation, 30 g of acetone was further added to the reaction vessel.

(6) Referring to Table 1, it was confirmed that when the ratio of replacement by cyanoethyl groups was 50%, δ.sub.D2, δ.sub.P2, and δ.sub.H2 of Equation 1 were 15.95 MPa.sup.1/2, 10.45 MPa.sup.1/2, and 12.80 MPa.sup.1/2, respectively. Further, when the ratio of replacement by cyanoethyl groups was 50%, acetone was added, and at this time, δ.sub.D1, δ.sub.P1, and δ.sub.H1 of Equation 1 were 15.75 MPa.sup.1/2, 13.22 MPa.sup.1/2, and 17.19 MPa.sup.1/2, respectively. When these solubility parameters were put into Equation 1, it was confirmed that Ra was 5.20 and less than 6 at 50% of the ratio of replacement by cyanoethyl groups.

(7) 30 minutes later, 3 g of acetic acid was added to the reaction vessel, and 300 g of distilled water was added to precipitate a reaction product. The precipitated polymer was dissolved in 200 g of acetone, and this solution was added to 300 g of distilled water to reprecipitate the cyanoethyl group-containing polymer. Ra values were monitored throughout the cyanoethylation to confirm that Ra values were maintained at less than 6.

EXAMPLE 2

Preparation of Cyanoethyl Group-Containing Polymer

(8) A cyanoethyl group-containing polymer was prepared in the same manner as in Example 1, except that the reaction temperature of Example 1 was controlled to 50° C. Ra values were monitored throughout the cyanoethylation to confirm that Ra values were maintained at less than 6.

EXAMPLE 3

Preparation of Cyanoethyl Group-Containing Polymer

(9) A cyanoethyl group-containing polymer was prepared in the same manner as in Example 1, except that when the ratio of replacement by cyanoethyl groups was 80%, 100 g of acetone was further added to the reaction vessel of Example 1. Ra values were maintained at about 5.52 throughout the cyanoethylation, indicating that Ra values were less than 6.

EXAMPLE 4

Preparation of Cyanoethyl Group-Containing Polymer

(10) 100 g of a 20% by weight polyvinyl alcohol aqueous solution (20 g of polyvinyl alcohol, 80 g of distilled water), 2 g of a 30% by weight NaOH aqueous solution (0.6 g of NaOH, 1.4 g of distilled water), and 150 g of acrylonitrile were added to a reaction vessel, and stirred at 30° C. to allow cyanoethylation.

(11) A ratio of replacement by cyanoethyl groups was monitored through H-NMR, and when the ratio of replacement by cyanoethyl groups was 30%, 50 g of dimethyl sulfoxide was added to the reaction vessel.

(12) Referring to Table 1, it was confirmed that when the ratio of replacement by cyanoethyl groups was 30%, δ.sub.D2, δ.sub.P2, and δ.sub.H2 of Equation 1 were 15.93 MPa.sup.1/2, 9.51 MPa.sup.1/2, and 15.20 MPa.sup.1/2, respectively. Meanwhile, when the ratio of replacement by cyanoethyl groups was 30%, dimethyl sulfoxide was added, and at this time, δ.sub.D1, δ.sub.P1, and δ.sub.H1 of Equation 1 were 16.29 MPa.sup.1/2, 14.41 MPa.sup.1/2, and 17.96 MPa.sup.1/2, respectively. When these solubility parameters were put into Equation 1, it was confirmed that Ra was 5.67 and less than 6 at 30% of the ratio of replacement by cyanoethyl groups.

(13) When the ratio of replacement by cyanoethyl groups reached 50% by continuing the cyanoethylation, 100 g of dimethyl sulfoxide was further added to the reaction vessel.

(14) Referring to Table 1, it was confirmed that when the ratio of replacement by cyanoethyl groups was 50%, δ.sub.D2, δ.sub.P2, and δ.sub.H2 of Equation 1 were 15.95 MPa.sup.1/2, 10.45 MPa.sup.1/2, and 12.80 MPa.sup.1/2, respectively. Further, when the ratio of replacement by cyanoethyl groups was 50%, dimethyl sulfoxide was added, and at this time, δ.sub.D1, δ.sub.P1, and δ.sub.H1 of Equation 1 were 16.86 MPa.sup.1/2, 14.97 MPa.sup.1/2, and 16.00 MPa.sup.1/2, respectively. When these solubility parameters were put into Equation 1, it was confirmed that Ra was 5.83 and less than 6 at 50% of the ratio of replacement by cyanoethyl groups.

(15) When the ratio of replacement by cyanoethyl groups reached 80% by continuing the cyanoethylation, 100 g of isopropyl alcohol was further added to the reaction vessel.

(16) Referring to Table 1, it was confirmed that when the ratio of replacement by cyanoethyl groups was 80%, δ.sub.D2, δ.sub.P2, and δ.sub.H2 of Equation 1 were 15.98 MPa.sup.1/2, 11.86 MPa.sup.1/2, and 9.20 MPa.sup.1/2, respectively. Further, when the ratio of replacement by cyanoethyl groups was 80%, isopropyl alcohol was added, and at this time, δ.sub.D1, δ.sub.P1, and δ.sub.H1 of Equation 1 were 17.43 MPa.sup.1/2, 14.56 MPa.sup.1/2, and 13.55 MPa.sup.1/2, respectively. When these solubility parameters were put into Equation 1, it was confirmed that Ra was 5.88 and less than 6 at 80% of the ratio of replacement by cyanoethyl groups.

(17) 30 minutes later, 3 g of acetic acid was added to the reaction vessel, and 300 g of distilled water was added to precipitate a reaction product. The precipitated polymer was dissolved in 200 g of acetone, and this solution was added to 3000 g of distilled water to reprecipitate the cyanoethyl group-containing polymer. Ra values were monitored throughout the cyanoethylation to confirm that Ra values were maintained at less than 6.

COMPARATIVE EXAMPLE 1

Preparation of Cyanoethyl Group-Containing Polymer

(18) 100 g of a 7% by weight polyvinyl alcohol aqueous solution, 2 g of a 30% by weight NaOH aqueous solution, and 100 g of acrylonitrile were added to a reaction vessel, and stirred at 50° C. for 1 hour to allow cyanoethylation. When the ratio of replacement by cyanoethyl groups reached 50% by monitoring the cyanoethylation, Ra of Equation 1 was calculated, and as a result, Ra was 12.32 and more than 6.

(19) Thereafter, 3 g of acetic acid was added to the reaction vessel, and 3000 g of distilled water was added to precipitate a reaction product. The precipitated polymer was dissolved in 200 g of acetone, and this solution was added to 3000 g of distilled water to reprecipitate the cyanoethyl group-containing polymer.

COMPARATIVE EXAMPLE 2

Preparation of Cyanoethyl Group-Containing Polymer

(20) A cyanoethyl group-containing polymer was prepared in the same manner as in Example 1, except that when the ratio of replacement by cyanoethyl groups was 30%, 100 g of distilled water was added to the reaction vessel of Example 1, and when the ratio of replacement by cyanoethyl groups was 50%, 100 g of distilled water was added to the reaction vessel of Example 1. In Comparative Example 2, when Ra of Equation 1 was calculated when the ratio of replacement by cyanoethyl groups was 30%, Ra was 16.21, and when Ra of Equation 1 was calculated when the ratio of replacement by cyanoethyl groups was 50%, Ra was 21.24, indicating that the Ra values were more than 6.

COMPARATIVE EXAMPLE 3

Preparation of Cyanoethyl Group-Containing Polymer

(21) 100 g of polyvinyl alcohol, 10 g of NaOH, and 200 g of acrylonitrile were added to a reaction vessel, and 400 mL (316.4 g) of acetone and 300 mL of distilled water were added thereto, and then stirred at 70° C. to allow cyanoethylation.

(22) 30 minutes later, when the ratio of replacement by cyanoethyl groups was 60%, 100 mL (79.1 g) of acetone was added to continue cyanoethylation. Ra of Equation 1 was calculated before addition of acetone, and as a result, Ra was 8.41. Ra of Equation 1 was calculated after addition of acetone, and as a result, Ra was 6.99, indicating that the Ra values were more than 6.

(23) 30 minutes later, 3 g of acetic acid was added to the reaction vessel, and 3000 g of distilled water was added to precipitate a reaction product. The precipitated polymer was dissolved in 200 g of acetone, and this solution was added to 3000 g of distilled water to reprecipitate the cyanoethyl group-containing polymer.

EXPERIMENTAL EXAMPLE

Examination of Structure of Cyanoethyl Group-Containing Polymer and Evaluation of Characteristics Thereof

(24) (1) Examination of Structure of Cyanoethyl Group-Containing Polymer

(25) Contents of the repeating unit containing —OCH.sub.2CH.sub.2CONH.sub.2 and ions thereof and the repeating unit containing —OCH.sub.2CH.sub.2COOH and ions thereof which are introduced into the cyanoethyl group-containing polymers prepared in the examples and comparative examples were examined by H-NMR and IR spectra, and the results are shown in Table 2. In detail, the ratios of the repeating unit containing —OCH.sub.2CH.sub.2CONH.sub.2 and ions thereof and the repeating unit containing —OCH.sub.2CH.sub.2COOH and ions thereof with respect to repeating units in each polymer were calculated through the peak area that appeared at 2.2 ppm to 2.3 ppm in the H-NMR spectrum and the peak area corresponding to —COO which appeared at 1570 cm.sup.−1 in the IR spectrum.

(26) TABLE-US-00002 TABLE 2 —OCH.sub.2CH.sub.2CONH.sub.2 and ions —OCH.sub.2CH.sub.2COOH and thereof ions thereof Example 1 0.4 <0.1 Example 2 0.4 <0.1 Example 3 0.3 <0.1 Example 4 0.7 <0.3 Comparative 5.2 3.0 Example 1 Comparative 4.2 7.1 Example 2 Comparative 2.1 2.5 Example 3 (Unit: %)

(27) (2) Evaluation of Characteristics of Cyanoethyl Group-Containing Polymer

(28) Each of the cyanoethyl group-containing polymers prepared in the examples and comparative examples was mixed with inorganic particles, and dispersion force and adhesive strength thereof were evaluated. In detail, the cyanoethyl group-containing polymer was mixed with alumina having an average particle size of 0.7 μm and BET of 4 m.sup.2/g at a weight ratio of 10:90 to prepare a slurry.

(29) In order to examine the dispersion force of the cyanoethyl group-containing polymer, the prepared slurry was rotated at 200 rpm by using a LUMiSizer which is a dispersion analyzer, and a sedimentation rate of alumina was measured at 25° C., and the results are shown in Table 3 below. As the dispersion force of the cyanoethyl group-containing polymer is better, the alumina is better dispersed and settles slowly.

(30) In order to evaluate the adhesive strength of the cyanoethyl group-containing polymer, an assembly was manufactured by adhering an electrode to one surface of a separator in the following manner, and a force required to peel the separator from the electrode was measured and is shown in Table 3 below.

(31) In detail, artificial graphite, carbon black, CMC, and a binder at a weight ratio of 96:1:1:2 were mixed with water to prepare a negative electrode slurry. The negative electrode slurry was coated on a copper foil with a thickness of 50 μm and dried at 80° C. for 1 hour or longer, and then pressed to manufacture a negative electrode.

(32) Thereafter, the prepared slurry of the cyanoethyl group-containing polymer and the inorganic particles was coated on one surface of a polyethylene porous substrate by using a doctor blade, and then dried to prepare a separator on which a porous coating layer was formed.

(33) The negative electrode and the separator were adhered to each other in a lamination device, and this sample was used to measure a force which was required to peel the adhesive surface of the electrode and the separator (porous coating layer) by using a UTM at a speed of 100 mm/min.

(34) TABLE-US-00003 TABLE 3 Sedimentation rate [μm/s] Electrode adhesive strength [g.sub.f/15 mm] Example 1 1.5 69 Example 2 1.2 72 Example 3 1.2 80 Example 4 3.4 55 Comparative 58 10 Example 1 Comparative 36 25 Example 2 Comparative 20.5 32 Example 3

(35) Referring to Table 3, the sedimentation rates of Examples 1 to 4 were lower than those of Comparative Examples 1 to 3, indicating improvement of dispersibility of inorganic particles, and the electrode adhesive strengths of Examples 1 to 4 were higher than those of Comparative Examples 1 to 3, indicating improvement of adhesive strength of inorganic particles. Accordingly, it was confirmed that the cyanoethyl group-containing polymer having low contents of the functional groups such as —OCH.sub.2CH.sub.2CONH.sub.2 and —OCH.sub.2CH.sub.2COOH may be used to achieve excellent dispersion force and adhesive strength.