Polyester type polymeric dispersant as well as preparation method and application thereof

Abstract

The invention belongs to the field of functional polymeric dispersants, and particularly relates to a polyester type polymeric dispersant as well as a preparation method and application thereof. The preparation method of the polyester type polymeric dispersant comprises the following steps: S1, reacting a reaction system containing cyclic lactone and short-chain small molecular acid under the condition of acid catalysis to obtain an intermediate; and S2, carrying out copolymerization reaction on the intermediate obtained in the step S1 and polyalkylimine at the temperature not higher than 100 DEG C for 1-2 hours to obtain the polyester type polymeric dispersant, the short-chain small-molecular acid comprises short-chain carboxylic acid with the carbon atom number less than or equal to 6. The polyester polymeric dispersant is of a comb-shaped structure multi-point adsorption type, is particularly suitable for dispersion of high-pigment carbon black pigment particles, has excellent dispersion stability and compatibility in different polar resin systems, and can be widely applied to the fields of printing ink, coatings and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of dispersants, and particularly relates to a polyester-type polymer dispersant and a preparation method and application thereof. Background Art

[0002] Dispersants are classified into two main categories: traditional dispersants and novel dispersants. Traditional dispersants include fatty acids, fatty amides, esters, paraffins, metallic soaps, and polymer waxes (such as polyethylene homopolymers or copolymers, polypropylene, and polystyrene). Typical examples of novel dispersants are polymeric dispersants. Polymeric dispersants are a highly effective class of polymeric dispersants that play a crucial role in coatings and inks due to their excellent dispersing properties. Their molecular structure contains two types of groups with opposing polarity and solubility. One type is the solvating segment, commonly found in polyolefins, polyesters, polyethers, and polyacrylates. These segments facilitate the dispersant's orientation on the pigment surface or at the interface between two phases, reducing interfacial tension, accelerating pigment surface wetting, and lowering system viscosity. The other type is the anchoring group, typically consisting of -COOH, -COO-, -SO3H, and polyamines. Polymer dispersants maintain the application performance of pigment particles in the medium through adsorption force and steric hindrance between them and the powder. Among them, the adsorption force is provided by the anchoring group, including electrostatic force, hydrogen bonding, conjugation, van der Waals force, etc., while the steric hindrance is provided by the solvated chain segment, including electrostatic repulsion, steric hindrance, etc.

[0003] Compared with traditional dispersants, polymer dispersants overcome their limitations in adsorbing pigment particles and have the following characteristics: (1) polymer dispersants can form multiple anchor points on the particle surface, which increases adsorption efficiency and is not easy to fall off; (2) the solvated chain segments are longer than those of traditional dispersants, which can provide a stronger three-dimensional space effect, reduce the viscosity of the system, and improve the stability of the pigment in the organic medium; (3) they can move quickly to the particle surface, accelerate the wetting of the pigment surface, and shorten the grinding time; (4) they do not affect the application performance of the final product.

[0004] The preparation and application of dispersants for inks and coatings have attracted widespread attention both domestically and internationally in recent years. Patent CN116023598A discloses a UV ink hyperdispersant, its preparation method, and its application. Using polyester polyol, a capping agent, a catalyst, and a block monomer as raw materials, this polymeric dispersant is formulated to effectively regulate the stability of the ink system. However, this dispersant has a limited number of anchoring groups, resulting in unstable anchoring of the pigment.

[0005] Invention patent CN116239765A discloses a polyetheramine-modified multi-block polymer dispersant, its preparation method, and application. The dispersant utilizes the amino groups of the block polyamine and the carboxylic acid residues formed by the ring opening of the acid anhydride as anchoring groups, the EO / PO polyether portion of the polyetheramine as the solvating chain, and a hydroxylated acrylate as a bridging moiety to connect the polyetheramine block portion with the acid anhydride and polyamine portions. Highly polar polyethylene polyamine and carboxyl groups serve as anchoring groups for inorganic ultrafine powders, allowing electrostatic adsorption to the surface of the inorganic ultrafine powders. The EO / PO copolymerized polyether then serves as the solvating chain to regulate steric hindrance and ionic electrostatic repulsion. However, this dispersant is ineffective for dispersing high-pigment carbon black particles.

[0006] Invention patent CN103881103A utilizes a cyclic lactone ring-opening polymerization reaction to obtain a polyester, which is then subjected to an esterification reaction with a long-chain fatty alcohol to obtain a polyester with a long-chain ester group. This polyester with a long-chain ester group is then subjected to an amidation reaction with polyethyleneimine to obtain the hyperdispersant. This hyperdispersant has good dispersibility for red toner, but is poorly compatible with high-pigment carbon black particles, and requires a high reaction temperature and a long reaction time.

[0007] Therefore, it is a technical problem that needs to be solved in the art to provide a high-efficiency preparation method that can be synthesized under low-temperature conditions and has a good dispersing effect on the high-pigment carbon black prepared. Summary of the Invention

[0008] In order to remedy the defects and deficiencies of the prior art, the primary purpose of the present invention is to provide a method for preparing a polyester-type polymer dispersant.

[0009] Another object of the present invention is to provide a polyester polymer dispersant prepared by the above method.

[0010] Another object of the present invention is to provide an application of the above polyester-based polymer dispersant.

[0011] The purpose of the present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a method for preparing a polyester-type polymer dispersant, the polyester-type polymer dispersant comprising the following steps: S1. A reaction system comprising a cyclic lactone and a short-chain small molecule acid is reacted under acid-catalyzed conditions to obtain a carboxyl-containing intermediate; S2. The intermediate obtained in step S1 is copolymerized with polyalkylene imine at a temperature not higher than 100° C. for 1 to 2 hours to obtain the polyester-type polymer dispersant; the short-chain small molecule acid includes a short-chain carboxylic acid having a carbon number of ≤6.

[0012] Preferably, the cyclic lactone comprises valerolactone and / or caprolactone.

[0013] More preferably, the cyclic lactones include valerolactone and caprolactone.

[0014] More preferably, the molar ratio between valerolactone and caprolactone is (0.5-2): (7-8.5).

[0015] When the cyclic lactone is caprolactone, the reaction mechanism is as follows: S1.

[0016] S2. .

[0017] Preferably, in step S1, the reaction temperature is 80-120°C, for example, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, etc.

[0018] More preferably, the reaction temperature in step S1 is 90-100° C., for example, 92, 94, 96, 98, etc.

[0019] Preferably, the reaction time is 1 to 2 hours.

[0020] Preferably, in step S2, the copolymerization reaction temperature is 60-100°C, for example, 58, 60, 65, 70, 75, 80, 85, 90, 95, etc.

[0021] More preferably, in step S2, the temperature of the copolymerization reaction is 60-80°C; more preferably 60-65°C.

[0022] The invention obtains a carboxyl-containing intermediate by using cyclic lactone and short-chain small molecular acid under acid catalysis, and realizes the preparation of polyester high molecular dispersant under low temperature conditions by combining with polyalkylene imine.

[0023] Preferably, the copolymerization reaction time is 1 to 2 hours.

[0024] Compared with the prior art, the preparation method provided by the present invention requires less time, has high production efficiency, low energy consumption and lower cost.

[0025] Preferably, the molar ratio between the cyclic lactone and the short-chain small molecule acid is 3.5-17.5:1; 3.5-17.5 can be 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, etc.

[0026] More preferably, the molar ratio between the cyclic lactone and the short-chain small molecule acid is 3.5-9:1.

[0027] More preferably, the molar ratio between the cyclic lactone and the short-chain small molecule acid is 7 to 9:1.

[0028] Preferably, the mass ratio between the intermediate and the polyalkylene imine is (0.6-0.85): (0.15-0.25).

[0029] Among them, (0.6~0.85) can take values ​​of 0.65, 0.7, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8, 0.81, 0.82, 0.83, 0.84, etc.; (0.15~0.25) can take values ​​of 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, etc.

[0030] Preferably, the mass ratio between the intermediate and the polyalkylene imine is (0.75-0.8): (0.15-0.2).

[0031] Preferably, the amount of the catalyst added is 0.1-0.2 wt% of the total weight of the reaction system.

[0032] Preferably, in step S1, the weight average molecular weight of the intermediate is 390-2000 g / mol.

[0033] Preferably, the weight average molecular weight of the polyester polymer dispersant is 5000-25000 g / mol.

[0034] Preferably, the short-chain small molecule acid includes one or more of glacial acetic acid, propionic acid, succinic acid, and adipic acid.

[0035] Preferably, the short-chain small molecule acid comprises glacial acetic acid.

[0036] Preferably, the polyalkylimine comprises polyethyleneimine and / or polyetheramine.

[0037] Preferably, the number average molecular weight of the polyalkylene imine is 300-20,000 g / mol; more preferably 1,800-10,000 g / mol.

[0038] Preferably, the acid catalyst used in the acid catalysis includes an organic acid catalyst.

[0039] Preferably, the acid catalyst comprises trifluoromethanesulfonic acid.

[0040] Preferably, in step S1, the reaction system includes a solvent.

[0041] Preferably, the solvent includes one or more of ethyl formate, ethyl acetate, n-butyl acetate, and isobutyl acetate.

[0042] In a second aspect, the present invention provides a polyester-type polymer dispersant, which is prepared according to the above-mentioned preparation method.

[0043] In a third aspect, the present invention provides a use of the above-mentioned polyester polymer dispersant as a high-pigment carbon black dispersant.

[0044] In a fourth aspect, the present invention provides a color paste comprising 15 to 25 parts by weight of high-melanin carbon black, 15 to 25 parts by weight of a dispersant, 74.8 parts by weight of a solvent, and 0.2 parts by weight of an auxiliary agent.

[0045] Wherein, the dispersant is a polyester polymer dispersant prepared according to the above method.

[0046] The auxiliary agent is one or more of a defoaming agent, a wetting agent and a leveling agent.

[0047] The mechanism of the present invention is:

[0048] The present invention uses acid-catalyzed ring-opening lactone polymerization to prepare a carboxyl-containing intermediate with controllable molecular weight. This carboxyl-containing intermediate is then modified with an alkylimine to produce a comb-like structured, multi-point adsorption polymer dispersant. The dispersant provided by the present invention utilizes the amino, hydroxyl, and carboxyl groups of polyamines as anchoring groups and polyesters as solvated segments, employing multi-point anchoring dispersion. Highly polar polyethylene polyamines and carboxyl groups serve as adsorption sites, anchoring the polymer to the surface of inorganic ultrafine powders through intermolecular interactions such as electrostatic adsorption and hydrogen bonding. The solvated segments regulate steric hindrance and electrostatic repulsion, promoting the dispersion of high-color carbon black pigment particles. The dispersant exhibits excellent dispersion stability and compatibility in various polarity systems.

[0049] The present invention has the following advantages and beneficial effects over the prior art: 1. The present invention produces a polyester-type polymeric dispersant by reacting a carboxyl-containing intermediate obtained by reacting a cyclic lactone with a short-chain small molecule acid with a polyalkylene imine. Due to the use of biodegradable and environmentally friendly raw materials, the polyester-type polymeric dispersant is also potentially biodegradable and has good compatibility with most resins. The polyester-type polymeric dispersant provided by the present invention contains multiple anchoring groups on its polymer chain backbone, which can strongly adsorb to the pigment surface and simultaneously have extended chains that form steric hindrance. The anchoring groups of the polymeric dispersant adhere to the surface of the pigment particles through electrostatic adsorption and hydrogen bonding, forming a strong and dense polymer coating. The polyester solvated chain segments then extend within the resin or solvent-based system, providing stable dispersion of the pigment particles through entropic stabilization. Furthermore, the polyester solvated chain segments can prevent particle aggregation through electrostatic repulsion or steric repulsion, thereby improving the stability of the dispersion system. When dispersing high-pigment carbon black, fineness can reach micrometers or even nanometers, increasing the pigment loading and significantly improving dispersion efficiency.

[0050] 2. The present invention realizes the synthesis of polyester dispersants under low temperature conditions. At the same time, the process is simple and easy to operate, the required production time is short, and the production efficiency can be greatly improved and the production cost can be reduced.

[0051] 3. The polymer dispersant provided by the present invention is in the form of a linear or branched polymer with a molecular weight of approximately 5000-20000 g / mol, which can provide better system dispersion stability. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be directly purchased from the market, and the process parameters not specifically noted can be carried out with reference to conventional techniques.

[0053] In the following examples, gel permeation chromatography (GPC) was used to measure molecular weight.

[0054] The total weight of the raw materials in step (1) of the following examples refers to the total weight of the short-chain small molecule acid, cyclic lactone and acid catalyst.

[0055] The total weight of solids in step (2) of the following examples refers to the sum of the weight of the solids of the intermediate and the weight of the polyalkylene imine. Example 1

[0056] (1) 1 mol part of glacial acetic acid, 9 mol parts of caprolactone, and 0.2 wt% of trifluoromethanesulfonic acid based on the total weight of the raw materials were added to a flask equipped with a condenser reflux device. 10 parts by mass of butyl acetate were added to create a solvent environment. Under nitrogen protection, the temperature was raised to 90°C. After mechanical stirring for 1 hour, the temperature was raised to 100°C again and the reaction was continued for 1 hour to obtain an intermediate. The weight average molecular weight of the intermediate was tested to be 1087 g / mol.

[0057] (2) The liquid obtained in step (1) was cooled to room temperature, polyethyleneimine (number average molecular weight of 1800 g / mol) was added at a ratio of 20 wt% of the total weight of the solid content, and the temperature was raised to 100° C. and the reaction was carried out for 1.5 h to prepare a polycaprolactone-type polymer dispersant with a reaction conversion rate of >95%. Example 2

[0058] (1) 1 mol of glacial acetic acid, 17.5 mol of caprolactone, and 0.2 wt% of trifluoromethanesulfonic acid (based on the total weight of the raw materials) were added to a flask equipped with a condenser reflux apparatus. 10 parts (by mass) of butyl acetate were added to create a solvent environment. The temperature was raised to 90°C and the mixture was stirred for 1 hour. The temperature was then raised to 100°C and the reaction was continued for 1 hour to obtain an intermediate. The weight-average molecular weight of the intermediate prepared was 1997 g / mol.

[0059] (2) The liquid obtained in step (1) was cooled to room temperature, polyethyleneimine (number average molecular weight of 2000 g / mol) was added at a ratio of 20 wt% of the total solid weight, and the temperature was raised to 65 ° C for reaction for 2 h to prepare a polycaprolactone type polymer dispersant with a reaction conversion rate of >95%. Example 3

[0060] (1) 1 mol part of glacial acetic acid, 0.5 mol part of valerolactone, 8.5 mol parts of caprolactone, and 0.2 wt% of the total weight of trifluoromethanesulfonic acid were added to a flask equipped with a condenser reflux apparatus. 10 parts by mass of butyl acetate were added to create a solvent environment. The temperature was raised to 90°C and the mixture was stirred for 1 hour. The temperature was then raised to 100°C and the reaction was continued for 1 hour to obtain an intermediate. The weight-average molecular weight of the prepared intermediate was 1020 g / mol.

[0061] (2) The liquid obtained in step (1) was cooled to room temperature, polyethyleneimine (number average molecular weight of 1800 g / mol) was added at a ratio of 20 wt% of the total weight of the solid content, and the temperature was raised to 100 ° C. and the reaction was carried out for 1.5 h to prepare a polycaprolactone type polymer dispersant, and the reaction conversion rate was >95%. Example 4

[0062] (1) 1 mol part of glacial acetic acid, 2 mol parts of valerolactone, 7 mol parts of caprolactone, and 0.2 wt% of the total weight of trifluoromethanesulfonic acid were added to a flask equipped with a condenser reflux apparatus. 10 parts by mass of butyl acetate were added to create a solvent environment. The temperature was raised to 90°C and the mixture was stirred for 1 hour. The temperature was then raised to 100°C and the reaction was continued for 1 hour to obtain an intermediate. The weight average molecular weight of the intermediate prepared was 999 g / mol.

[0063] (2) The liquid obtained in step (1) was cooled to room temperature, polyethyleneimine (number average molecular weight of 1800 g / mol) was added at a ratio of 20 wt% of the total weight of the solid content, and the temperature was raised to 100 ° C. and the reaction was carried out for 1.5 h to prepare a polycaprolactone type polymer dispersant, and the reaction conversion rate was >95%. Example 5

[0064] (1) 1 mol of glacial acetic acid, 3.5 mol of caprolactone, and 0.2 wt% of trifluoromethanesulfonic acid based on the total weight of the raw materials were added to a flask equipped with a condenser reflux device. 10 parts by mass of butyl acetate were added to create a solvent environment. The temperature was raised to 90 °C and the mixture was stirred for 1 hour. The temperature was then raised to 100 °C and the reaction was continued for 1 hour to obtain a polycaprolactone intermediate. The weight average molecular weight of the prepared intermediate was 399 g / mol.

[0065] (2) The liquid obtained in step (1) was cooled to room temperature, polyethyleneimine (number average molecular weight of 300 g / mol) was added at a ratio of 20 wt% of the total weight of the solid content, and the temperature was raised to 100 ° C and reacted for 1.5 h to prepare a polycaprolactone type polymer dispersant, and the reaction conversion rate was >95%. Example 6

[0066] The only difference between this example and Example 1 is that the reaction conditions in step (1) of this example are to first heat the temperature to 80°C, react with stirring for 1 hour, then heat the temperature to 100°C again, and continue to react for 1 hour. Example 7

[0067] The only difference between this embodiment and embodiment 1 is that the reaction conditions in step (1) of this embodiment are to first heat the mixture to 110°C, react with stirring for 1 hour, then heat the mixture to 120°C again, and continue the reaction for 1 hour. Example 8

[0068] The only difference between this embodiment and embodiment 1 is that the reaction condition in step (2) of this embodiment is to heat the reaction to 60° C. and react for 1.5 h. Example 9

[0069] The only difference between this embodiment and embodiment 1 is that the amount of polyethyleneimine (molecular weight 1800 g / mol) added in step (2) of this embodiment is changed to 30 wt% of the total weight of the solid content. Example 10

[0070] The only difference between this embodiment and embodiment 1 is that the short-chain molecular acid used in this embodiment is n-hexanoic acid. Comparative Example 1

[0071] (1) 1 mol part of glacial acetic acid, 3.5 mol parts of caprolactone and 0.2 wt% of the total weight of the raw materials, trifluoromethanesulfonic acid were added to a flask equipped with a condensing reflux device, 10 parts by mass of butyl acetate were added, a solvent environment was created, the temperature was raised to 90 °C, the reaction was carried out under stirring for 1 hour, the temperature was raised to 100 °C again, and the reaction was continued for 1 hour to obtain a polycaprolactone intermediate; after testing, the molecular weight of the obtained polycaprolactone was 399 g / mol.

[0072] (2) The liquid obtained in step (1) was cooled to room temperature, tetraethylene pentamine was added at a ratio of 30 wt% of the total weight of the solid content, and the temperature was raised to 100 ° C and reacted for 1.5 h to prepare a polycaprolactone type polymer dispersant. Comparative Example 2

[0073] (1) 1 mol of glacial acetic acid, 3.5 mol of caprolactone, and 0.2 wt% of trifluoromethanesulfonic acid were added to a flask equipped with a condenser reflux apparatus. 10 wt% of butyl acetate was added to create a solvent environment. The temperature was raised to 90°C and stirred for 1 hour. The temperature was then raised to 100°C and the reaction was continued for 1 hour to obtain a polycaprolactone intermediate. The molecular weight of the obtained polycaprolactone was 399 g / mol.

[0074] (2) The liquid obtained in step (1) was cooled to room temperature, tetraethylene pentamine was added at a ratio of 40 wt% of the total weight of the solid content, and the temperature was raised to 100 ° C and reacted for 1.5 h to prepare a polycaprolactone type polymer dispersant. Comparative Example 3

[0075] The only difference between this comparative example and Example 1 is that in this comparative example, glacial acetic acid is replaced by n-octanoic acid in the same molar proportion.

[0076] Test Case

[0077] The raw materials and addition amounts shown in Table 1 were mixed and shaken on a high-speed dispersion tester for 1 hour to prepare a high-pigment carbon black slurry. The dispersant was the polyester polymer dispersant obtained in Examples 1 to 10 and Comparative Examples 1 to 3. The resulting color paste was tested according to the following method to evaluate the color paste's performance. The test results are shown in Table 1.

[0078] (1) Viscosity: Tested using a viscometer (BROOKFIELD DV2T Viscometer). The lower the viscosity value, the better the dispersion performance.

[0079] (2) Fineness: Tested using an ISO scraper fineness meter.

[0080] (3) Glossiness: The color paste prepared in each embodiment and comparative example was coated on a hiding power test cardboard, and tested using a gloss meter according to the method in the national standard GB / T 9754-2007.

[0081] Table 1

[0082]

[0083] As can be seen from Table 1, the high-pigment carbon black slurry obtained by using the dispersants prepared in Examples 1 to 10 of the present invention has the characteristics of low viscosity, better fineness and glossiness, etc., which shows that the dispersants prepared in the examples of the present invention have excellent dispersibility for high-pigment carbon black.

[0084] The high-pigment carbon black slurries obtained in Comparative Examples 1-3 had excessively high viscosities, making them unsuitable for testing. This suggests that the dispersants provided in Comparative Examples 1-3 were inadequate for dispersing high-pigment carbon black, resulting in insufficient dispersion of the pigment particles and an inability to produce a low-viscosity, high-pigment carbon black slurry.

[0085] In summary, the polyester-based polymer dispersants provided in the embodiments of the present invention exhibit excellent dispersion and stability for high-pigment carbon black. The present invention demonstrates, through Examples and Comparative Examples 1-2, that polyethyleneimine provides more anchoring groups than polyethylene polyamines. Furthermore, the polyethyleneimine used in these embodiments is not a completely linear polymer but rather contains partial branches, including primary, secondary, and tertiary amines, resulting in high adhesion, adsorption, and reactivity. The polymer dispersants provided in the embodiments of the present invention have a simple preparation process, significantly reducing reaction temperatures and catalyst dosages compared to traditional processes. They are also environmentally friendly, with low VOC (volatile organic compound) content, enabling industrial-scale production.

[0086] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a polyester-type polymer dispersant, characterized in that: The polyester polymer dispersant comprises the following steps: S1. A reaction system comprising a cyclic lactone and a short-chain small molecule acid is reacted under acid-catalyzed conditions to obtain a carboxyl-containing intermediate; S2. The intermediate obtained in step S1 is copolymerized with a polyalkylene imine at not more than 100 ° C for 1 to 2 hours to obtain the polyester polymer dispersant; The short-chain small molecule acid includes a short-chain carboxylic acid with a carbon number of ≤6.

2. The method for preparing a polyester-type polymer dispersant according to claim 1, wherein: In step S1, the reaction temperature is 80-120°C; Preferably, the reaction temperature is 90-100°C; Preferably, the reaction time is 1 to 2 hours.

3. The method for preparing a polyester-type polymer dispersant according to claim 1, wherein: In step S2, the copolymerization reaction temperature is 60-100°C, preferably 60-80°C; more preferably 60-65°C.

4. The method for preparing a polyester-type polymer dispersant according to claim 1, wherein: The molar ratio between the cyclic lactone and the short-chain small molecule acid is 3.5 to 17.5: 1; more preferably 3.5 to 9: 1; Preferably, the mass ratio between the intermediate and the polyalkylene imine is (0.7-0.85): (0.15-0.3); Preferably, the mass ratio between the intermediate and the polyalkylene imine is (0.75-0.8): (0.25-0.2); Preferably, the amount of the catalyst added is 0.1-0.2 wt% of the total weight of the reaction system.

5. The method for preparing a polyester-type polymer dispersant according to claim 1, wherein: In step S1, the weight average molecular weight of the intermediate is 390-2000 g / mol; Preferably, the weight average molecular weight of the polyester polymer dispersant is 5000-25000 g / mol.

6. The method for preparing a polyester-type polymer dispersant according to claim 1, wherein: The short-chain small molecule acid includes one or more of glacial acetic acid, propionic acid, succinic acid, and adipic acid; Preferably, the short-chain small molecule acid comprises glacial acetic acid; Preferably, the cyclic lactone comprises valerolactone and / or caprolactone; More preferably, the cyclic lactones include valerolactone and caprolactone; More preferably, the molar ratio between valerolactone and caprolactone is (0.5-2): (7-8.5); Preferably, the polyalkylimine comprises polyethyleneimine and / or polyetheramine; Preferably, the number average molecular weight of the polyalkylene imine is 300-20000 g / mol, more preferably 1800-10000 g / mol.

7. The method for preparing a polyester-type polymer dispersant according to claim 1, wherein: The acid catalyst used for the acid catalysis includes organic acid catalysts, Preferably, the acid catalyst comprises trifluoromethanesulfonic acid; Preferably, in step S1, the reaction system comprises a solvent; preferably, the solvent comprises one or more of ethyl formate, ethyl acetate, n-butyl acetate, and isobutyl acetate.

8. A polyester polymer dispersant, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the polyester polymer dispersant as claimed in claim 8 as a high pigment carbon black dispersant.

10. A black color paste, characterized in that: The invention comprises 15 to 25 parts by weight of high-melanin carbon black, 15 to 25 parts by weight of a dispersant, 74.8 parts by weight of a solvent and 0.2 parts by weight of an auxiliary agent; The dispersant comprises a polyester polymer dispersant prepared according to the preparation method according to any one of claims 1 to 7.

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