Branched dispersant as well as preparation method and application thereof

Abstract

The invention discloses a branched dispersant as well as a preparation method and application thereof, and belongs to the technical field of materials. The branched dispersant comprises an inner core and chain arms, the inner core is a polymer with amino groups, the chain arms comprise chain arms with alkyl chain segments and chain arms with polyether chain segments and / or carboxyl chain segments, and the chain arms are connected with the inner core through the amino groups on the inner core through covalent bonds. The dispersing agent has excellent dispersing performance, can be widely applied to dispersion of carbon materials, is particularly suitable for dispersion of positive electrode slurry, and has the advantages of good dispersion and viscosity reduction, good slurry stability and the like.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a branched dispersant and a preparation method and application thereof. Background Art

[0002] In recent years, with the development of the new energy industry, carbon materials such as carbon nanotubes, graphene, and conductive carbon black have been widely used. Due to their special particle structure and surface morphology, when these carbon materials are not used with dispersants or with traditional polyvinyl pyrrolidone dispersants, the prepared slurry will have problems such as inability to disperse or poor dispersibility, high slurry viscosity, and short storage time, thus affecting subsequent use. Summary of the invention

[0003] In view of the above problems, the present invention provides a branched dispersant, which has excellent dispersing properties and can be widely used in the dispersion of carbon materials, especially suitable for the dispersion of positive electrode slurry, and has the advantages of good dispersion and viscosity reduction, good slurry stability and the like.

[0004] The present invention provides a branched dispersant, comprising a core and chain arms, wherein the core is a polymer having an amine group, the chain arms include chain arms having an alkyl segment, and chain arms having a polyether segment and / or a carboxyl segment, and the chain arms are connected to the core by covalent bonds via amino groups on the core.

[0005] In some embodiments, the number average molecular weight of the core is 500-10000, preferably 600-10000; further, the number average molecular weight of the core is 700-3000, and further, the number average molecular weight of the core is 800-2000, for example, 800, 2000.

[0006] In some embodiments, the alkyl segment has a structural fragment represented by the following formula (I):

[0007]

[0008]

[0009] In formula (I), z is an integer of 4-24, preferably an integer of 12-18, for example, 12 or 18, more preferably 18.

[0010] In some embodiments, the number average molecular weight of the chain arms having polyether segments is 300-3000, preferably 1500-2500, for example 2000.

[0011] In some embodiments, the polyether segment has a structural fragment represented by the following formula (II):

[0012]

[0013] In formula (II), R1 is H or CH3, R2 is a C1-C8 alkyl group, and y is an integer of 8-70, preferably 35-46.

[0014] In some embodiments, the carboxyl segment has a structural fragment represented by the following formula (III):

[0015]

[0016] In formula (III), R3 is -CH2-, R4 is H or CH3; R3 is H or CH3, R4 is a C1-C8 alkyl group, and x is an integer of 8-70, preferably 35-46.

[0017] In some embodiments, the number average molecular weight of the chain arm having a carboxyl segment is 300-3000, preferably 500-2000.

[0018] In some embodiments, the covalent bond is an amide bond or a CN bond.

[0019] In some embodiments, the core is selected from: polyethyleneimine; preferably branched polyethyleneimine, such as: Lupasol series polyethyleneimine, Epomin series polyethyleneimine, further preferably: Lupasol FG, Lupasol PR8515.

[0020] In some embodiments, the chain arm having an alkyl chain segment is selected from one or more of alkyl acrylates, fatty acid methyl esters and monofunctional aliphatic isocyanates; preferably, the alkyl chain segment is selected from C4H9, C6H 13 , C8H 17 , C 12 H 25 , C 16 H 33 , C 18 H 37 , C 20 H 41 , C 22 H 45 , C 24 H 49 More preferably, at least one of methyl stearate, octadecyl acrylate and dodecyl acrylate, for example, methyl stearate and / or octadecyl acrylate.

[0021] In some embodiments, the chain arm having a polyether segment is selected from: end-capped polyether (meth) acrylate or an intermediate obtained by ring-opening maleic anhydride and a monofunctional end-capped polyether containing a hydroxyl group or an amine group at the end. Preferably, the polyether segment is selected from: at least one of polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether, and poly(ethylene oxide-propylene oxide) monomethyl ether; preferably, at least one of polyethylene glycol 480 monomethyl ether acrylate, polyethylene glycol 400 monomethyl ether methacrylate, the reaction product of maleic anhydride and Genamin M41 / 2000, and the reaction product of maleic anhydride and Polyglykol B11 / 30.

[0022] In some embodiments, the chain arm having a carboxyl segment is selected from acrylic acid, and an intermediate obtained by ring-opening maleic anhydride with a monofunctional end-capped polyether containing a hydroxyl group or an amine group at the end.

[0023] In some embodiments, the amount of the chain arms having alkyl segments is 1%-50% of the total mass of the branched dispersant, preferably 19%-50%.

[0024] In some embodiments, the amount of the chain arms having polyether segments is 1%-60% of the total mass of the branched dispersant, preferably 20%-60%, more preferably 40%-60%, for example 45%-60%.

[0025] In some embodiments, the amount of the chain arms having carboxyl segments is 1%-60% of the total mass of the branched dispersant, preferably 1%-20%, for example: 2%-11%.

[0026] On the other hand, the present invention also discloses a method for preparing the branched dispersant, comprising the following steps:

[0027] Chain arm mixing: mixing a chain arm having a polyether segment and / or a carboxyl segment with a chain arm raw material having an alkyl segment in a solvent to obtain a chain arm mixture;

[0028] Grafting: adding the core into the mixture of the chain arms to react so that the chain arms are connected to the core through the amino groups on the core by covalent bonds.

[0029] In some embodiments, the solvent is selected from at least one of water, alcohol solvents, ester solvents, ketone solvents, aromatic hydrocarbon solvents, N-methylpyrrolidone, and N,N-dimethylformamide; for example, N-methylpyrrolidone.

[0030] In some embodiments, the amount of the solvent is 1-10 times, preferably 1-5 times, and more preferably 1-2 times the total mass of the chain arm.

[0031] In some embodiments, in the grafting step, the reaction temperature is 40-120°C, preferably 60-70°C.

[0032] In some embodiments, in the grafting step, the reaction time is 1-8 hours, preferably 4-7 hours, for example 6 hours.

[0033] In some embodiments, before the chain arm mixing step, a chain arm preparation step is also included, and the chain arm preparation step is: dissolving maleic anhydride in a solvent, and then adding a monofunctional terminated polyether containing a hydroxyl group or an amino group at the end, reacting, and obtaining a chain arm raw material having a polyether segment and a carboxyl segment.

[0034] In some embodiments, the molar ratio of the hydroxyl or amine group to the maleic anhydride is 1:1.

[0035] In some embodiments, the reaction temperature is 20-90°C, preferably 20-40°C.

[0036] In some embodiments, the reaction time is 0.5-4 hours, preferably 0.5-2 hours, for example 1 hour.

[0037] On the other hand, the present invention also discloses the use of the branched dispersant in dispersing carbon materials.

[0038] In some embodiments, the carbon material is selected from at least one of pigment carbon black, conductive carbon black, carbon nanotubes, graphene and carbon-coated materials.

[0039] On the other hand, the present invention also discloses a carbon material dispersion liquid, comprising: a carbon material and the above-mentioned branched dispersant.

[0040] In some embodiments, the carbon material is selected from at least one of pigment carbon black, conductive carbon black, carbon nanotubes, graphene and carbon-coated materials.

[0041] In some embodiments, the carbon material dispersion includes lithium iron phosphate, conductive carbon black, PVDF and the branched dispersant.

[0042] For example, the carbon material dispersion includes 59.43 wt % of lithium iron phosphate, 0.427 wt % of conductive carbon black, 1.098 wt % of PVDF and 0.0488 wt % of the branched dispersant.

[0043] symbol Indicates the site where the fragment is connected to other groups.

[0044] The above-mentioned "hyperbranched polyethyleneimine" (HPEI for short) is a highly branched repeating unit polymer composed of ethylenediamine groups, and the end of the branch chain contains a large number of amine groups such as primary amino groups, secondary amino groups and tertiary amino groups, which can be used as the connection basis of the chain arms.

[0045] The above-mentioned "alkyl acrylate" is an ester obtained from acrylic acid and an alkyl group, such as octadecyl acrylate, dodecyl acrylate and the like.

[0046] The above-mentioned "fatty acid methyl ester" is an ester formed by an esterification reaction between a long-chain fatty acid and methanol, such as methyl stearate, methyl laurate, etc.

[0047] The above-mentioned “end-capped polyether (meth)acrylate” is a polymer obtained by end-capping a polyether with a (meth)acrylate.

[0048] The above-mentioned "monofunctional capped polyether containing hydroxyl or amine groups at the end" means that a terminal hydroxyl group on the polyether is capped by a capping agent, such as polyethylene glycol monomethyl ether, etc. "Monofunctional" refers to a single functional group, such as a polyether segment containing only one amine group.

[0049] The above-mentioned "carbon-coated materials" are materials formed by forming a carbon layer on the surface of the material through a carbon-forming agent, such as lithium iron phosphate, lithium manganese iron phosphate, etc.

[0050] The above-mentioned “PVDF” is polyvinylidene fluoride (PVDF), which is obtained by polymerizing vinylidene fluoride monomers.

[0051] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0052] The reagents and raw materials used in the present invention are commercially available.

[0053] The positive and progressive effects of the present invention are:

[0054] A branched dispersant of the present invention uses a polymer with an amine group as a core, uses the amine group as a reactive group, and covalently connects a chain arm with an alkyl segment and a chain arm with a polyether segment and / or a carboxyl segment, wherein the chain arm with the polyether segment and / or the carboxyl segment can stabilize the slurry by providing steric hindrance and / or electrostatic repulsion, and the chain arm with the alkyl segment can be surface-adsorbed with dispersed substances such as carbon materials to play an anchoring role, and synergistically play a good dispersing effect. The branched dispersant has the advantages of good dispersing effect and high dispersion stability.

[0055] The preparation method of the branched dispersant of the present invention has the advantages of simple and stable process and is suitable for industrial production.

[0056] The dispersed material obtained by using the branched dispersant of the present invention, such as carbon material dispersion liquid, positive electrode slurry, etc., has the advantages of good dispersion and viscosity reduction, good slurry stability, etc. It can improve the efficiency of dispersion in the future later production, increase production capacity, and reduce the energy consumption of the dispersion process. DETAILED DESCRIPTION

[0057] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0058] Lupasol PR8515, purchased from BASF, is a branched polyethyleneimine with a number average molecular weight of ∼2000;

[0059] Lupasol FG, purchased from BASF, is a branched polyethyleneimine with a number average molecular weight of ∼800;

[0060] Polyethylene glycol 480 monomethyl ether acrylate, i.e. polyethylene glycol monomethyl ether acrylate (Mn480) (CAS: 32171-39-4), was purchased from Shanghai Titan Technology Co., Ltd., with a number average molecular weight of 480;

[0061] Polyethylene glycol 400 monomethyl ether methacrylate, i.e., poly(ethylene glycol) methacrylate (CAS: 25736-86-1), was purchased from Shanghai Titan Technology Co., Ltd., with a number average molecular weight of about 400;

[0062] Genamin M41 / 2000, purchased from Clariant, is a polyether monoamine with primary amine groups and a number average molecular weight of 2000;

[0063] Polyglykol B11 / 30, purchased from Clariant, is a polyether with hydroxyl groups and has a number average molecular weight of 1000;

[0064] PVP K30 was purchased from BASF and is polyvinyl pyrrolidone with a number average molecular weight of about 30,000; Example

[0065] 1. Preparation of branched dispersant AG

[0066] For ease of description, the core of the polymer having an amine group is referred to as core A, the chain arm having a polyether segment is referred to as chain arm B, the chain arm having a carboxyl segment is referred to as chain arm C, and the chain arm having an alkyl segment is referred to as chain arm D.

[0067] According to Table 1 below, chain arm B, link arm C, link arm D and 63.1 g of N-methylpyrrolidone as a solvent were added to a 250 ml four-necked round-bottom flask, a condenser and a thermometer were installed, and then a mechanical stirrer was turned on. Kernel A was slowly added, and after the addition was completed, the temperature was raised to 70°C, and the reaction was continued for 6 hours without purification to obtain branched dispersant AH.

[0068] Table 1. Raw material formula

[0069]

[0070] 2. Preparation of branched dispersant I

[0071] In a 100ml four-necked round-bottom flask, add 0.55g of maleic anhydride and 29g of N-methylpyrrolidone as reaction solvents, install a condenser and a thermometer, and then turn on the mechanical stirrer. Slowly add 11.22g of Genamin M41 / 2000, control the temperature not higher than 40°C, and keep it not higher than 40°C after the addition is complete. Keep the temperature for 1 hour to obtain a polymer having the structure of the following formula IV, which has both carboxylic acid functional groups and polyether functional groups, and has the functions of chain arms B and C.

[0072]

[0073] R1 is H or CH3, y=35-46.

[0074] After the heat preservation was completed, 11.26 g of octadecyl acrylate (chain arm D) was added, and after mixing evenly, 6 g of Lupasol PR8515 (core A) was slowly added. After the addition was completed, the temperature was raised to 60° C. and the heat preservation reaction was continued for 6 hours to obtain branched dispersant I.

[0075] 3. Preparation of branched dispersant J

[0076] Add 1.0g maleic anhydride and 28g N-methylpyrrolidone as reaction solvents to a 100ml four-necked round-bottom flask, install a condenser and a thermometer, and then turn on the mechanical stirrer. Slowly add 10.2g Polyglykol B11 / 30, and keep the temperature at no higher than 90°C for 1h after the addition. A polymer with the following formula V is obtained, which has both carboxylic acid functional groups and polyether functional groups, and has the functions of chain arms B and C.

[0077]

[0078] R1 is H or CH3, y=35-46.

[0079] After the heat preservation is completed, 10.93 g of octadecyl acrylate (chain arm D) is added, and after mixing evenly, 6 g of Lupasol PR8515 (core A) is slowly added. After the addition is completed, the temperature is raised to 60°C, and the heat preservation reaction is continued for 6 hours to obtain branched dispersant J.

[0080] Comparative Example

[0081] 1. Preparation of comparative dispersant A

[0082] In a 100 ml four-necked round-bottom flask, add 20.0 g of polyethylene glycol 480 monomethyl ether acrylate, 8.66 g of acrylic acid and 34.66 g of N-methylpyrrolidone, install a condenser and a thermometer, and then turn on the mechanical stirrer. Slowly add 6 g of Lupasol 8515, raise the temperature to 70 ° C after the addition, and continue to keep the temperature for 6 hours to obtain a product without chain arm D, which is comparative dispersant A.

[0083] 2. Preparation of comparative dispersant B

[0084] Add 0.55g maleic anhydride and 29g N-methylpyrrolidone to a 100ml four-necked round-bottom flask, install a condenser and a thermometer, and then turn on the mechanical stirrer. Start heating to 100°C, slowly add 11.22g Genamin M41 / 2000, and keep the temperature for 1h.

[0085] After the heat preservation was completed, 11.26 g of octadecyl acrylate was added, mixed evenly, and then 6 g of Lupasol PR8515 was slowly added. After the addition was completed, the temperature was raised to 60°C and the heat preservation reaction was continued for 6 hours. After cooling and discharging, the product was separated into two phases and could not be used as a dispersant.

[0086] Effect experiment example

[0087] This experimental example takes the NMP solvent system as an example to illustrate the application effect of the branched dispersant AJ obtained in the example in carbon materials.

[0088] The experiment was conducted using polyvinyl pyrrolidone (PVP K30) commonly used in the market, a comparative dispersant A prepared in a comparative example, and a control without adding a dispersant.

[0089] Specifically, based on the mass, the lithium iron phosphate addition amount was 59.43%, and 0.0488% of the above-mentioned branched dispersant AJ, comparative dispersant A, 0.427% of conductive carbon black and 1.098% of PVDF were added respectively, and oscillated for 4 hours, and a blank group (no dispersant added) and a comparative sample PVP K30 group were set as controls.

[0090] Then, the rotational viscosity was tested after the temperature was kept constant at 25°C. The test method was as follows: the test was conducted using a Brookfield rotational viscometer, with a 64# rotor controlling the speed at 30 rpm, the test lasted for 3 minutes, and the viscosity value was read. After standing for 2 hours and 24 hours, the viscosity was tested again to observe its stability.

[0091] The results are shown in the following table.

[0092] Table 2. Dispersion properties of each dispersant

[0093]

[0094] It can be seen from the above results that the branched dispersants AJ prepared by the present invention have a discharge viscosity less than that of PVP K30, indicating that their dispersibility is better. Among them, dispersants AE and IJ have very excellent performance. The dispersibility of branched dispersant F is slightly reduced due to the added chain arm D being laurylate, while the dispersibility of branched dispersants G or H is slightly reduced due to the lack of added chain arm B or chain arm C and the lack of polyether segment or carboxyl segment, but their discharge viscosity is better than PVP K30.

[0095] It can be seen from the blank experiment that without adding dispersant, the viscosity of the discharged slurry has reached 16,000, indicating that when the viscosity of the discharged slurry is too high, its viscosity increase is not large.

Claims

1. A branched dispersant, characterized in that: It includes a core and chain arms, wherein the core is a polymer with an amine group, the chain arms include chain arms with an alkyl segment, and chain arms with a polyether segment and / or a carboxyl segment, and the chain arms are covalently bonded to the core through the amino group on the core.

2. The branched dispersant according to claim 1, characterized in that Meets one or more of the following conditions: (1) The number average molecular weight of the core is 500-10000, preferably 600-10000; further, the number average molecular weight of the core is 700-3000, and further, the molecular weight of the core is 800-2000, for example, 800, 2000; (2) The alkyl segment has a structural fragment shown in the following formula (I): In formula (I), z is an integer of 4-24, preferably an integer of 12-18, for example, 12 or 18, more preferably 18; (3) The number average molecular weight of the chain arms having polyether segments is 300-3000, preferably 1500-2500, for example 2000; (4) The polyether segment has a structural fragment shown in the following formula (II): In formula (II), R1 is H or CH3, R2 is a C1-C8 alkyl group, and y is an integer of 8-70, preferably 35-46; (5) The carboxyl segment has a structural fragment shown in the following formula (III): In formula (III), R3 is -CH2-, R4 is H or CH3; R1 is H or CH3, R2 is a C1-C8 alkyl group, and x is an integer of 8-70, preferably 35-46; (6) The number average molecular weight of the chain arm having a carboxyl chain segment is 300-3000, preferably 500-2000; (7) The covalent bond is an amide bond or a CN bond.

3. The branched dispersant according to claim 2, characterized in that Meets one or more of the following conditions: (1) The core is selected from: polyethyleneimine; preferably branched polyethyleneimine, such as: Lupasol series polyethyleneimine, Epomin series polyethyleneimine, and more preferably: LupasolFG, Lupasol PR8515; (2) The chain arm having an alkyl chain segment is selected from one or more of alkyl acrylates, fatty acid methyl esters and monofunctional aliphatic isocyanates; preferably, the alkyl chain segment is selected from C4H9, C6H 13 , C8H 17 , C 12 H 25 , C 16 H 33 , C 18 H 37 , C 20 H 41 , C 22 H 45 , C 24 H 49 One or more; more preferably at least one of methyl stearate, octadecyl acrylate, and dodecyl acrylate, for example, methyl stearate and / or octadecyl acrylate; (3) The chain arms having polyether segments are selected from: end-capped polyether (meth)acrylates or intermediates obtained by ring-opening maleic anhydride with a monofunctional end-capped polyether containing a hydroxyl group or an amino group at the end. Preferably, the polyether segments are selected from: at least one of polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether, and poly(ethylene oxide-propylene oxide) monomethyl ether; preferably, at least one of polyethylene glycol 480 monomethyl ether acrylate, polyethylene glycol 400 monomethyl ether methacrylate, the reaction product of maleic anhydride and Genamin M41 / 2000, and the reaction product of maleic anhydride and Polyglykol B11 / 30; (4) The chain arms having carboxyl segments are selected from acrylic acid and intermediates obtained by ring-opening maleic anhydride with a monofunctional polyether terminated with a hydroxyl group or an amine group at the end.

4. The branched dispersant according to claim 3, characterized in that Meets one or more of the following conditions: (1) The amount of the chain arm having an alkyl chain segment is 1% to 50% of the total mass of the branched dispersant, preferably 19% to 50%; (2) The amount of the chain arms having polyether segments is 1%-60% of the total mass of the branched dispersant, preferably 20%-60%, more preferably 40%-60%; for example 45%-60%; (3) The amount of the chain arms having carboxyl segments is 1%-60% of the total mass of the branched dispersant, preferably 1%-20%, for example 2%-11%.

5. The method for preparing a branched dispersant according to any one of claims 1 to 4, characterized in that: The following steps are involved: Chain arm mixing: mixing a chain arm having a polyether segment and / or a carboxyl segment with a chain arm raw material having an alkyl segment in a solvent to obtain a chain arm mixture; Grafting: adding the core into the mixture of the chain arms to react so that the chain arms are connected to the core through the amino groups on the core by covalent bonds.

6. The method for preparing a branched dispersant according to claim 5, characterized in that: Meet one or more of the following conditions: (1) The solvent is selected from at least one of water, alcohol solvents, ester solvents, ketone solvents, aromatic hydrocarbon solvents, N-methylpyrrolidone, and N,N-dimethylformamide; for example, N-methylpyrrolidone; (2) The amount of the solvent is 1-10 times, preferably 1-5 times, more preferably 1-2 times the total mass of the chain arm; (3) In the grafting step, the reaction temperature is 40-120°C, preferably 60-70°C; (4) In the grafting step, the reaction time is 1-8 hours, preferably 4-7 hours, for example 6 hours.

7. The method for preparing a branched dispersant according to claim 5, wherein: Before the chain arm mixing step, a chain arm preparation step is also included, wherein the chain arm preparation step comprises: dissolving maleic anhydride in a solvent, and then adding a monofunctional capped polyether having a hydroxyl group or an amino group at the end, and reacting to obtain a chain arm raw material having a polyether segment and a carboxyl segment; Further, the molar ratio of the hydroxyl or amine group to the maleic anhydride is 1:1; Furthermore, the reaction temperature is 20-90° C., preferably 20-40° C.; and / or the reaction time is 0.5-4 hours, preferably 0.5-2 hours, for example 1 hour.

8. Use of the branched dispersant according to any one of claims 1 to 4 in dispersing carbon materials.

9. The use according to claim 8, characterized in that The carbon material is selected from at least one of pigment carbon black, conductive carbon black, carbon nanotubes, graphene and carbon-coated materials.

10. A carbon material dispersion, characterized in that: The invention comprises: a carbon material and the branched dispersant according to any one of claims 1 to 4.

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