Dispersant having low viscosity and low molecular weight

Abstract

The present invention relates to a conductive material dispersion for a secondary battery and a slurry composition comprising same for a secondary battery electrode. Specifically, the conductive material dispersion, which exhibits excellent performance compared with existing dispersants due to the inclusion of a vinyl-based dispersant, can be used for a secondary battery electrode.

Description

Dispersants with low viscosity and low molecular weight

[0001] The present invention relates to a dispersant having low viscosity and low molecular weight. Specifically, the invention relates to a dispersant having a viscosity of 30 to 600 cPs and a molecular weight of 20,000 to 220,000 g / mol.

[0002] Japanese patent JP 6804806 B2 discloses a method for dispersing a conductive material in a dispersion medium, but the invention is not optimized for dispersing conductive materials. Furthermore, EP 3770204 A1 defines the structure of the dispersant as a polymer containing aromatic vinyl monomer units and linear alkylene structural units having four or more carbon atoms. However, this structure presents a problem in that it is not suitable for dispersing conductive materials with hydroxyl groups on the surface.

[0003] A related prior art document is JP 6801806 B2.

[0004] The present invention seeks to provide a dispersant with excellent dispersing properties. The dispersant of the present invention may have the characteristics of low viscosity and low molecular weight.

[0005] A dispersant according to one embodiment of the present invention may include a hydrogenated nitrile rubber polymer having a weight average molecular weight of 20,000 g / mol to 220,000 g / mol as measured by gel permeation chromatography.

[0006] The above hydrogenated nitrile rubber polymer may be manufactured through a depolymerization reaction of a hydrogenated nitrile rubber polymer having a weight average molecular weight of 220,000 g / mol or more.

[0007] A dispersant according to one embodiment of the present invention may include the following chemical formula 1.

[0008] [Chemical Formula 1]

[0009]

[0010] The above l is 0.3 to 0.5,

[0011] The above m is 0.2 to 0.3,

[0012] The above n is 0.2 to 0.5,

[0013] The above h is 0 to 0.01,

[0014] The above l+m+n+h=1.

[0015] The acryl nitrile (ACN) content of the above hydrogenated nitrile rubber may be 20 to 50 wt% based on the total weight of the hydrogenated nitrile rubber polymer.

[0016] The acid value of the above hydrogenated nitrile rubber may be 0 to 10 mg KOH / g.

[0017] A dispersant according to one embodiment of the present invention may specifically include a polymer defined by the following chemical formula 2.

[0018] [Chemical Formula 2]

[0019]

[0020] wherein R is hydrogen or methyl,

[0021] The above p and q are each independently 0 to 0.2,

[0022] The above o and s are each independently 0.2 to 0.7,

[0023] The above r is 0.2 to 0.5,

[0024] The above t is 0 to 0.1,

[0025] The above o+p+q+r+s+t=1.

[0026] A compound containing an amine group can be bonded to the carboxylic acid group of the above hydrogenated nitrile rubber.

[0027] The compound containing the above amine group may be methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, or oleylamine.

[0028] Specifically, the compound containing the amine group may be one or two or more selected from methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, and oleylamine.

[0029] The molecular weight of the above dispersant may be 20,000 to 220,000 g / mol.

[0030] The viscosity of the above dispersant may be 30 to 600 cPs.

[0031] A conductive dispersion according to one embodiment of the present invention may include a dispersant, a conductive material, and a dispersion medium.

[0032] The above-mentioned challenge material may be one selected from carbon nanotubes, graphene oxide, graphene nanoplates, carbon black, and reduced graphene oxide.

[0033] The above dispersion may be one or two or more selected from n-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, xylene, toluene, hexane, heptane, octane, cyclohexane, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, methanol, ethanol, butanol, isopropyl alcohol, glycerol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxy propanol, tetrahydrofuran, formic acid, acrylonitrile, glycol ether, and water.

[0034] The purpose of the present invention is to provide a conductive material dispersant that improves electrical connection by defining the structure of a dispersant that facilitates dispersion of conductive materials such as carbon nanotubes, graphene, and carbon black in a medium, thereby inducing uniform dispersion in a cathode slurry of a secondary battery, thereby increasing the lifespan and efficiency of the secondary battery.

[0035] Figure 1 shows the H-NMR results of dispersants having different molecular weight values.

[0036] Figure 2 shows the results of C-NMR of dispersants having different molecular weight values.

[0037] Figure 3 shows the results of GPC of a dispersant manufactured according to Comparative Example 1.

[0038] Figure 4 shows the results of GPC of a dispersant manufactured according to Comparative Example 2.

[0039] Figure 5 shows the results of GPC of a dispersant manufactured according to Example 1 of the present invention.

[0040] Figure 6 shows the results of GPC of a dispersant manufactured according to Example 2 of the present invention.

[0041] Figure 7 shows the results of GPC of a dispersant manufactured according to Example 3 of the present invention.

[0042] Figure 8 shows the results of GPC of a dispersant manufactured according to Example 4 of the present invention.

[0043] Figure 9 shows the results of GPC of a dispersant manufactured according to Example 5 of the present invention.

[0044] Figure 10 shows the results of GPC of a dispersant manufactured according to Example 6 of the present invention.

[0045] Figure 11 shows the results of GPC of a dispersant manufactured according to Example 7 of the present invention.

[0046] The terms and words used in this specification and claims described below should not be construed as limited to their usual or dictionary meanings, but should be construed as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the terms to best describe his or her invention.

[0047] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

[0048] When a part of a specification is said to "include" a component, this does not exclude other components, but rather implies the inclusion of other components, unless otherwise specifically stated. Furthermore, when a part is said to be "connected" to another part, this includes not only cases where the two parts are "directly connected," but also cases where the two parts are "electrically connected" with other elements intervening.

[0049] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the present invention. The singular forms used herein include the plural forms unless the context clearly dictates otherwise. Furthermore, the terms "comprise" and / or "comprising" as used herein specify the presence of stated features, steps, numbers, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, numbers, operations, elements, components, and / or groups thereof.

[0050] In addition, the term "connection" used in this specification not only means that certain elements are directly connected, but also includes an indirect connection where another element is interposed between the elements.

[0051] Below, with reference to the attached drawings, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In addition, in the drawings, parts irrelevant to the description are omitted for clarity of description, and similar parts are designated with similar reference numerals throughout the specification.

[0052] A dispersant according to one embodiment of the present invention may include a hydrogenated nitrile rubber polymer having a weight average molecular weight of 20,000 g / mol to 220,000 g / mol as measured by gel permeation chromatography.

[0053] Specifically, the dispersant may contain 5 to 30 wt% of the hydrogenated nitrile rubber polymer relative to the total weight of the dispersant. Within this range, the viscosity of the dispersant may be low, resulting in excellent dispersion properties. For example, the dispersant may contain 7 to 28 wt%. For example, the dispersant may contain 10 to 25 wt%.

[0054] The above hydrogenated nitrile rubber polymer may be manufactured by depolymerizing a hydrogenated nitrile rubber polymer having a weight average molecular weight of 220,000 g / mol or more.

[0055] The above depolymerization can be carried out under high-speed and high-pressure conditions for the hydrogenated nitrile rubber polymer. For example, the depolymerization can be carried out at a speed of 1,000 to 9,000 rpm. For example, the depolymerization can be carried out at a speed of 3,000 to 9,000 rpm.

[0056] For example, the depolymerization may proceed at 1 to 3,000 bar. For example, the depolymerization may proceed at 1 to 2,000 bar.

[0057] The above hydrogenated nitrile rubber polymer may have a structure represented by the following chemical formula 1.

[0058] [Chemical Formula 1]

[0059]

[0060] The above l is 0.3 to 0.5,

[0061] The above n is 0.2 to 0.3,

[0062] The above m is 0.2 to 0.5,

[0063] The above h is 0 to 0.01,

[0064] The above can be ㅣ+m+n+h=1.

[0065] Specifically, in the chemical formula 1, l of the dispersant is 0.4,

[0066] n can be 0.3.

[0067] The acrylonitrile (ACN) content of the hydrogenated nitrile rubber may be 15 to 40 wt% based on the total weight of the hydrogenated nitrile rubber polymer. For example, it may be 16 to 39 wt%.

[0068] The acid value of the above hydrogenated nitrile rubber may be 0 to 10 mg KOH / g.

[0069] A dispersant according to one embodiment of the present invention may specifically include a polymer defined by the following chemical formula 2.

[0070] [Chemical Formula 2]

[0071]

[0072] wherein R is hydrogen or methyl,

[0073] The above p and q are each independently 0 to 0.2,

[0074] The above o and s are each independently 0.2 to 0.7,

[0075] The above r is 0.2 to 0.5,

[0076] The above t is 0 to 0.1,

[0077] The above o+p+q+r+s+t=1.

[0078] A compound containing an amine group can be bonded to the carboxylic acid group of the above hydrogenated nitrile rubber.

[0079] The compound containing the above amine group may be methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, or oleylamine.

[0080] The compound containing the above amine group may be selected from a primary amine, a secondary amine, a tertiary amine, an aromatic amine, or a mixture thereof. However, the present invention is not limited thereto, and any type of primary amine, secondary amine, tertiary amine, or aromatic amine commonly used in this field may be used without any problem.

[0081] Specifically, the compound containing the amine group may be one or two or more selected from methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, and oleylamine.

[0082] The compound containing the above amine group may be used by mixing it in advance with the dispersant to form a salt, or may be used together with a conductive agent during dispersion. However, it is preferable to mix and react it in advance with the dispersant to form an ion bond in order to sufficiently form a salt.

[0083] The compound containing the above amine group may be present in an amount of 10 to 60 parts by weight, preferably 20 to 50 parts by weight, based on the solid content of the dispersant, per 100 parts by weight.

[0084] If it is below the above range, the dispersibility may decrease and the amount of conductive material may decrease, and if it is above the above range, it may have a negative effect on the properties of the secondary battery.

[0085] The above dispersant may be a dispersant according to the embodiment of the present invention. Specifically, the dispersant may include a hydrogenated nitrile rubber polymer having a weight average molecular weight of 20,000 g / mol to 220,000 g / mol as measured by gel permeation chromatography.

[0086] The viscosity of the dispersant according to one embodiment of the present invention may have a viscosity value of 30 to 600 cPs.

[0087] Specifically, as a dispersant according to one embodiment of the present invention, the dispersant comprising the chemical formula 1 may have a viscosity value of 50 to 550 cPs. In addition, the dispersant comprising the chemical formula 1 may have a molecular weight of 50,000 to 200,000 g / mol.

[0088] Specifically, as a dispersant according to another embodiment of the present invention, the dispersant comprising chemical formula 2 may have a viscosity value of 30 to 580 cPS. In addition, the dispersant comprising chemical formula 2 may have a molecular weight of 20,000 to 200,000 g / mol.

[0089] A dispersion according to one embodiment of the present invention may include a dispersant, a conductive agent, and a solvent.

[0090] The above dispersion may contain 1 to 3 parts by weight of the dispersant, 87 to 94 parts by weight of the solvent, and 5 to 10 parts by weight of the conductive agent, relative to the total weight of the dispersion. Preferably, the dispersion may contain 1 to 1.5 parts by weight of the dispersant, 93.5 to 94 parts by weight of the solvent, and 5 parts by weight of the conductive agent.

[0091] The above-mentioned conductive material may be one or two or more selected from multi-wall carbon nanotubes, single-wall carbon nanotubes, carbon black, or graphene.

[0092] The above solvent may be one or two or more selected from the group consisting of n-methyl-2-pyrrolidone, trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, methylene chloride, ethylene chloride, monochlorobenzene, dichlorobenzene, and trichlorobenzene.

[0093] A slurry composition for a cathode according to one embodiment of the present invention may include the dispersion, cathode active material, binder, and solvent.

[0094] Figure 1 illustrates the H-NMR results of dispersants having different molecular weight values. The dispersants disclosed in Figure 1 can have molecular weights of 190,000 g / mol to 334,000 g / mol. The dispersants disclosed in Figure 1 are dispersants of ready-made products, and the dispersant of the present invention can be produced as a dispersant with lower viscosity and lower molecular weight than existing products by using the dispersant of the ready-made product.

[0095] Figure 2 shows the C-NMR results of dispersants having different molecular weight values.

[0096]

[0097] Comparative Example 1.

[0098] A dispersant having an ACN content of 34% and a molecular weight of 210,000 g / mol, as disclosed in Fig. 1, was used. 92 g of the solvent NMP and 8 g of the hydrogenated nitrile rubber polymer were placed in a reactor and dissolved at high temperature. Dissolution was carried out under a nitrogen atmosphere with stirring for 12 hours from the time the temperature reached 80°C.

[0099]

[0100] Comparative Example 2.

[0101] A dispersant having an ACN content of 34% and a molecular weight of 210,000 g / mol, as disclosed in Fig. 1, was used, and 8 g of rubber in which an amine compound is ionically bonded to the carboxylic acid group of hydrogenated nitrile rubber and 92 g of solvent NMP were placed in a reaction tank and dissolved at high temperature. Dissolution was carried out under a nitrogen atmosphere with stirring for 12 hours from the time the temperature reached 80°C.

[0102]

[0103] Example 1.

[0104] A dispersant having an ACN content of 34% and a molecular weight of 210,000 g / mol as disclosed in Fig. 1 was used, and 92 g of solvent NMP and 8 g of hydrogenated nitrile rubber polymer were placed in a reaction tank to prepare a solution.

[0105] Afterwards, the prepared solution was depolymerized for 6 hours at 3,000 rpm and 0 psi using a high-speed, high-pressure treatment device. The high-speed treatment device used a rotosolver, homogenizer, plaretary mixer, or butterfly mixer, and the high-pressure treatment device used a sonolator, high-pressure autoclave, or a device manufactured in combination with a high-pressure homogenizer.

[0106]

[0107] Example 2.

[0108] The same procedure as Example 1 was followed, except that the depolymerization reaction was performed for 6 hours under the conditions of 6,000 rpm and 7,500 psi.

[0109]

[0110] Example 3.

[0111] The same procedure as Example 1 was followed, except that the depolymerization reaction was carried out for 6 hours under the conditions of 6,000 rpm and 15,000 psi.

[0112]

[0113] Example 4.

[0114] The same method as Example 1 was used, except that the depolymerization reaction was performed for 6 hours under the conditions of 9,000 rpm and 15,000 psi.

[0115]

[0116] Example 5.

[0117] The same procedure as Example 1 was followed, except that the depolymerization reaction was carried out for 6 hours under the conditions of 9,000 rpm and 20,000 psi.

[0118]

[0119] Example 6.

[0120] The same procedure as Example 1 was followed, except that the depolymerization reaction was carried out for 6 hours under the conditions of 9,000 rpm and 30,000 psi.

[0121]

[0122] Example 7.

[0123] A dispersant having an ACN content of 34% and a molecular weight of 210,000 g / mol as disclosed in Fig. 1 was used, and 8 g of rubber in which an amine compound is ionically bonded to the carboxylic acid group of hydrogenated nitrile rubber and 92 g of solvent NMP were placed in a reaction tank to prepare a solution. The prepared solution was subjected to a depolymerization reaction for 6 hours under the conditions of 9,000 rpm and 30,000 psi using the high-speed, high-pressure processing device of Example 1.

[0124]

[0125] Experimental Example. Measurement of molecular weight and viscosity of dispersant.

[0126] The molecular weight of the dispersants of the above comparative examples and examples was measured using HLC-8320GPC from TOSOH.

[0127] The viscosity of the dispersants of the above comparative examples and examples was measured using BROOKFIELD's DV2T under the condition of 62 spindles.

[0128] Referring to the data disclosed in Table 1 below, it can be confirmed that the dispersant of the present invention has low viscosity and low molecular weight compared to conventional dispersants.

[0129] Table 1 below summarizes the high-speed / high-pressure processing conditions, molecular weight, and viscosity of the comparative examples and examples.

[0130] High-speed and high-pressure processing conditionsMolecular weight (g / mol)Viscosity (cPs)Comparative example 1--220,793,600Comparative example 2--220,793,580Example 13,000rpm0psi193,125,550Example 26,000rpm7,500psi160,559,388.5Example 36,000rpm15,000psi144,267,260.5Example 49,000rpm15,000psi116,516,186.8Example 59,000rpm20,000psi100,587,126.3Example 69,000rpm30,000psi36,151,51.2Example 79,000rpm30,000psi36,15130

Claims

1. A dispersant comprising a hydrogenated nitrile rubber polymer having a weight average molecular weight of 20,000 g / mol to 220,000 g / mol as measured by gel permeation chromatography.

2. In paragraph 1, A dispersant characterized in that the hydrogenated nitrile rubber polymer is produced through a depolymerization reaction of a hydrogenated nitrile rubber polymer having a weight average molecular weight of 220,000 g / mol or more.

3. In paragraph 1, The above hydrogenated nitrile rubber is a polymer defined by the following chemical formula 1: [Chemical Formula 1] The above l is 0.3 to 0.5, The above m is 0.2 to 0.3, The above n is 0.2 to 0.5, The above h is 0 to 0.01, Dispersant, where l+m+n+h=1.

4. In paragraph 1, A dispersant characterized in that the acrylonitrile (ACN) content of the hydrogenated nitrile rubber is 15 to 40 wt% based on the total weight of the hydrogenated nitrile rubber polymer.

5. In paragraph 1, A dispersant characterized in that the acid value of the hydrogenated nitrile rubber is 0 to 10 mg KOH / g.

6. In paragraph 1, The above dispersant is a dispersant comprising a polymer defined by the following chemical formula 2: [Chemical Formula 2] In the above chemical formula 2, wherein R is hydrogen or methyl, The above p and q are each independently 0 to 0.2, The above o and s are each independently 0.2 to 0.7, The above r is 0.2 to 0.5, The above t is 0 to 0.1, The above o+p+q+r+s+t=1.

7. In paragraph 3, Characterized by a mixture or ion bond of a compound containing an amine group to the carboxylic acid group of the above hydrogenated nitrile rubber, Dispersant.

8. In paragraph 7, The compound containing the above amine group is at least one selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, and oleylamine. Dispersant.

9. In paragraph 1, The molecular weight of the above dispersant has a value of 20,000 to 220,000 g / gmol, Dispersant.

10. In paragraph 1, The viscosity of the above dispersant has a value of 30 to 600 cPS, Dispersant.

11. A dispersant according to any one of paragraphs 1 to 10; including a challenge agent; and a dispersion medium; Dispersion.

12. In paragraph 11, The above-mentioned conductive material is one selected from multi-wall carbon nanotubes, single-wall carbon nanotubes, carbon black, or graphene. Dispersion.

13. In paragraph 11, The above dispersion medium is one or more selected from n-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, xylene, toluene, hexane, heptane, octane, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, methanol, ethanol, butanol, isopropyl alcohol, glycerol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxy propanol, tetrahydrofuran, formic acid, acrylonitrile, glycol ether, and water. Dispersion.

14. Dispersion according to Article 11; Containing a cathode active material, a binder and a solvent, Slurry composition for secondary battery cathode.

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