CN118638292A

CN118638292A - Asymmetric branched polyurethane thickener with multiple arms, and preparation method and application thereof

Info

Publication number: CN118638292A
Application number: CN202410720411.1A
Authority: CN
Inventors: 陈惠珊; 汤柳燕; 卿宁; 孙小艺
Original assignee: Wuyi University
Current assignee: Wuyi University
Priority date: 2024-06-05
Filing date: 2024-06-05
Publication date: 2024-09-13

Abstract

The invention discloses an asymmetric branched polyurethane thickener with multiple arms, a preparation method and application thereof, wherein the preparation raw materials comprise: diisocyanate, polyethylene glycol, branched chain extender, end capping agent and polymerization catalyst; the preparation raw materials of the branched chain extender comprise: diisocyanate, polyol, diol and polymerization catalyst; the polymerization catalyst of the branched chain extender and the polymerization catalyst of the asymmetric branched polyurethane thickener with multiple arms are the same or different. The invention provides an asymmetric branched polyurethane thickener with multiple arms, which forms a more stable hydrophobic association network structure, reduces the fluidity of an aqueous system, and has stronger thickening performance and better stability compared with the traditional linear polyurethane thickener.

Description

Asymmetric branched polyurethane thickener with multiple arms, and preparation method and application thereof

Technical Field

The invention belongs to the field of fine chemicals such as water-based paint, textile printing, water-based resin coating and the like, and particularly relates to an asymmetric branched polyurethane thickener with multiple arms, and a preparation method and application thereof.

Background

The thickener is widely applied to the fields of cosmetics, foods, medicines, emulsion paint, dyes, adhesives, leather, papermaking and the like, and the current common thickeners are as follows: (1) Inorganic thickeners, such as bentonite, are low in price and strong in corrosion resistance, and have the defects of poor leveling property and poor compatibility: (2) Cellulose, such as carboxymethyl cellulose, is easily corroded and degraded by bacteria, and has poor corrosion resistance; (3) Polyacrylate, such thickener is easily affected by pH value and electrolyte, and has poor thixotropic property and poor hydrolysis resistance; (4) urethane associative thickeners; the traditional urethane associative thickener has a single molecular structure, is generally a linear structure with double-end hydrophobic and middle hydrophilic, and achieves a thickening effect in an emulsion system through a two-point association mode; although the rheological property is good, the thickening ability is poor, and the thickening ability is easily affected by temperature and solvent to be poor. Meanwhile, the existing side long chain alkyl modified comb-shaped associative polyurethane thickener with better thickening performance cannot be uniformly dispersed in a solution system, so that the local thickening speed is lower and the overall thickening capacity is reduced. The branched polyurethane thickener with better thickening performance contains a plurality of hydrophobic ends, and each branched chain is provided with a polyether chain segment with a certain length so as to ensure the hydrophilicity of the thickener, but the branched cores such as glycerol, pentaerythritol, xylitol, sorbitol, tris and the like are used, and because the central framework of the core is smaller, the hydroxyl functional groups are active, the distance between active groups is closer, and other branched chains are lack for isolating active groups. These tend to result in reaction processes that are difficult to control on the product structure, especially in the case of chain extension, which are prone to excessive crosslinking and thus to telangiectasia; meanwhile, the micromolecular polyol is used as a chain extender, and the synthesized thickener product is extremely easy to mutually intertwine due to self-hydrophobic chains, and forms spherical micelles due to self-association, so that the thickener product is difficult to associate with emulsion, solid particles and the like in a thickening system, and the thickening effect is reduced. Moreover, the intertwined molecular chains are difficult to stretch in a dilute solution, so that the water solubility of the molecules is affected, and the problems of long-term water separation and the like occur in the application process.

In view of the above, it is an urgent need to provide a polyurethane thickener having better stability and thickening properties.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems in the prior art described above. Therefore, the invention provides the asymmetric branched polyurethane thickener with multiple arms, which forms a more stable hydrophobic association network structure, reduces the fluidity of an aqueous system, and has stronger thickening performance and better stability compared with the traditional linear polyurethane thickener.

In a first aspect, the present invention provides an asymmetrically branched polyurethane thickener with multiple arms, prepared from the following raw materials: diisocyanate, polyethylene glycol, branched chain extender, end capping agent and polymerization catalyst;

The branched chain extender is prepared from the following raw materials: diisocyanates, polyols, diols, and polymerization catalysts.

The asymmetric branched polyurethane thickener with multiple arms has at least the following beneficial effects:

① In the invention, as the branched core of the branched chain extender has a larger central framework and larger active group spacing, and the formed chain extension branches are favorable for inhibiting the intramolecular association and strengthening the intermolecular association; meanwhile, the risk of sudden aggregation in the prior art can be effectively prevented, the defect that common polyol branched polyurethane associative thickeners are easy to generate excessive crosslinking is avoided to a certain extent, and the actual production is more feasible; the associative thickener has two association states, one is that a plurality of lipophilic terminal groups in a thickener structure are in one micelle (intramolecular self-association), and a collar structure is formed. This structure hardly contributes to the viscosity. The other is that a plurality of lipophilic end groups in the thickener structure are in different micelles (intermolecular association) to form a bridging structure. This structure can form a three-dimensional network structure, thereby increasing the viscosity of the system. The chain extender (branched core) prepared by the invention has larger central framework, larger distance between chain extension branches outwards and larger distance between each active group (OH), and then reacts with the polyurethane prepolymer containing NCO ends to form the long distance between branched chains of thickener molecules, so that the distance between the end lipophilic groups of each branched chain is farther, the association of the lipophilic groups of the same molecule is reduced, and the association of the lipophilic groups among different thickener molecules is improved.

② The branched chain extender prepared by the invention is used as a skeleton of a central branch structure, and each central branch is grafted with a hydrophilic polyether chain segment (polyethylene glycol) and a hydrophobic association alkyl long chain (end capping agent), so that the nonionic polyethylene glycol hydrophilic chain segment on each branched chain is obtained to ensure the water solubility of the product, the thickening agent obtains higher thickening speed in a dilute solution, and meanwhile, the anti-water separation performance of the thickening agent is improved.

③ The central skeleton branched core has the adjustability of the branched chain number, so that the number of the hydrophobic chains of the product is controllable, and the problems of poor product dispersion, poor water dispersibility and the like caused by out-of-control of the number of the hydrophobic chain segments are avoided; meanwhile, the molecular weight and the proportion of the hydrophilic and hydrophobic chain segments in the branched chain can be adjusted, so that the viscosity of the obtained polyurethane associative thickener can be adjusted.

④ The active groups of the branched cores used in the invention are different in activity, so that the molecular branched structure of the prepared thickener is different, and the branched structure of the thickener is an asymmetric structure, so that the product has a more abundant structure and more excellent comprehensive performance.

In some embodiments of the invention, the diisocyanate comprises at least one of Toluene Diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and Hexamethylene Diisocyanate (HDI).

In some embodiments of the invention, the polyethylene glycol comprises at least one of PEG4000, PEG6000, and PEG 8000.

In some embodiments of the present invention, the preparation raw materials of the asymmetric branched polyurethane thickener having multiple arms further include: an organic solvent;

the organic solvent comprises at least one of N, N-dimethylacetamide, N-dimethylformamide, acetone, butanone and N-methylpyrrolidone.

In some embodiments of the present invention, the preparation raw materials of the asymmetric branched polyurethane thickener having multiple arms further include: hydrophilic linear chain extenders;

The hydrophilic linear chain extender comprises at least one of an anionic chain extender and a cationic chain extender;

The anionic chain extender comprises at least one of dimethylolpropionic acid and dimethylolbutyric acid;

the cationic chain extender comprises at least one of N-methyldiethanolamine and N-butyldiethanolamine.

In some embodiments of the invention, the capping agent comprises one or more of higher alcohols such as n-hexadecanol, n-octadecanol, isotridecyl alcohol polyoxyethylene ether, and C16-18 alcohol polyoxyethylene ether.

In some embodiments of the invention, the catalyst comprises at least one of triethylamine, dibutyltin dilaurate, organobismuth, stannous octoate, dibutyltin maleate, and zinc octoate.

In some embodiments of the present invention, the preparation raw materials of the asymmetric branched polyurethane thickener having multiple arms further include: a cosolvent;

The cosolvent comprises at least one of diethylene glycol butyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, N-methyl pyrrolidone and N-ethyl pyrrolidone.

In some embodiments of the invention, the capping agent comprises at least one of a higher alcohol and an alcohol polyoxyethylene ether.

In some embodiments of the invention, the higher alcohols include at least one of n-hexadecanol and n-octadecanol.

In some embodiments of the invention, the alcohol-polyoxyethylene ether comprises a C16-18 alcohol-polyoxyethylene ether.

In some embodiments of the invention, the alcohol polyoxyethylene ether comprises an isomeric tridecanol polyoxyethylene ether.

In some embodiments of the invention, the polymerization catalyst comprises: at least one of dibutyltin dilaurate, stannous octoate, organic bismuth and triethylamine.

In a second aspect, the present invention provides a method for preparing the asymmetric branched polyurethane thickener with multiple arms, comprising the following steps:

a1: dispersing polyethylene glycol, diisocyanate and a polymerization catalyst, and then performing a prepolymerization reaction to obtain a mother solution;

A2: the mother solution obtained in the step A1 reacts with the end capping agent to obtain a reaction stock solution;

A3: and (3) mixing the reaction stock solution obtained in the step (A2) with the branched chain extender for reaction.

In some preferred embodiments of the invention, the method for preparing the asymmetric branched polyurethane thickener with multiple arms comprises the following steps:

A2: the mother solution obtained in the step A1 reacts with the hydrophilic linear chain extender and then reacts with the end capping agent to obtain a reaction stock solution;

In some embodiments of the invention, in step A2, the temperature at which the mother liquor and the hydrophilic linear chain extender react is from 60 ℃ to 70 ℃.

In some embodiments of the invention, in step A2, the temperature at which the mother liquor and the hydrophilic linear chain extender react is 60 ℃, 61 ℃, 62 ℃, 63 ℃, 64 ℃, 65 ℃, 66 ℃, 67 ℃, 68 ℃, 69 ℃, or 70 ℃.

In some embodiments of the invention, in step A2, the mother liquor and the hydrophilic linear chain extender are reacted for a period of time ranging from 40 to 70 minutes.

In some embodiments of the invention, in step A2, the mother liquor and the hydrophilic linear chain extender are reacted for a time of 40min, 45min, 50min, 55min, 60min, 65min or 70min.

In some embodiments of the present invention, in step A2, the mother liquor and the hydrophilic linear chain extender are reacted to obtain a reaction stock solution of a linear polyurethane thickener intermediate having a main chain containing a hydrophilic structure.

In some embodiments of the present invention, the reaction stock of the linear polyurethane thickener intermediate of hydrophilic structure and the capping agent react at a temperature of 85 to 95 ℃.

In some embodiments of the present invention, the reaction stock of the linear polyurethane thickener intermediate of hydrophilic structure and the capping agent react at a temperature of 85 ℃, 86 ℃, 87 ℃, 88 ℃, 89 ℃, 90 ℃, 91 ℃, 92 ℃, 93 ℃, 94 ℃ or 95 ℃.

In some embodiments of the present invention, the reaction stock of the linear polyurethane thickener intermediate of hydrophilic structure and the capping agent react for 90min, 100min, 110min, 120min, 130min, 140min, or 150min.

In some embodiments of the invention, in step A3, the temperature of the mixing reaction is 55 to 65 ℃.

In some embodiments of the invention, in step A3, the temperature of the mixing reaction is 55 ℃, 56 ℃, 57 ℃, 58 ℃, 59 ℃, 60 ℃, 61 ℃, 62 ℃, 63 ℃, 64 ℃, or 65 ℃.

In some embodiments of the invention, in step A3, the mixing reaction takes 180 to 360 minutes.

In some embodiments of the invention, in step A3, the mixing reaction is for 80min, 210min, 240min, 270min, 3000min, 330min or 360min.

In some embodiments of the present invention, in step A3, the mixing reaction further includes: and mixing the polymer of the asymmetric branched polyurethane thickener with multiple arms obtained by the reaction with a cosolvent and deionized water to obtain the asymmetric branched polyurethane thickener polymer thickener with the solid content of 19-21%.

In some embodiments of the present invention, step A1 further comprises a pretreatment of polyethylene glycol: and (3) melting the polyethylene glycol, heating to 120-125 ℃, and dehydrating for 2-3 h under the vacuum degree of minus 0.08-minus 0.1 MPa.

In some preferred embodiments of the present invention, in step A1, the dispersing temperature is: 60-70 ℃.

In some embodiments of the invention, the temperature of the prepolymerization is 75℃to 85 ℃.

In some embodiments of the invention, the temperature of the prepolymerization reaction is 75 ℃, 76 ℃, 77 ℃, 78 ℃, 79 ℃,80 ℃, 81 ℃, 82 ℃, 83 ℃, 84 ℃ or 85 ℃.

In some embodiments of the invention, the prepolymerization is carried out for a period of time ranging from 180 to 240miin.

In some embodiments of the invention, the time of the prepolymerization is 180min, 190min, 200min, 210min, 220min, 230min or 240min.

In some embodiments of the invention, the method for preparing the asymmetric branched polyurethane thickener with multiple arms comprises the following steps:

a1: dispersing 120-140 parts of polyethylene glycol, 7-17 parts of diisocyanate and 0.2-0.4 part of polymerization catalyst, and then carrying out prepolymerization reaction to obtain mother liquor;

a2: c, reacting the mother solution obtained in the step A1 with 4-10 parts of the end capping reagent to obtain a reaction stock solution;

A3: and (3) mixing and reacting the reaction stock solution obtained in the step (A2) with 10-29 parts of branched chain extender.

In some embodiments of the invention, the branched chain extender is prepared by a process comprising: : 40 to 50 parts of diisocyanate, 6 to 8 parts of polyol and 0.2 to 0.3 part of polymerization catalyst are subjected to chain extension and then react with 15 to 26 parts of dihydric alcohol to obtain the modified polyurethane.

In some embodiments of the invention, the branched chain extender is prepared by a process comprising: : b1: adding 40-50 parts of diisocyanate, 6-8 parts of polyol and 0.2-0.3 part of polymerization catalyst into a four-necked flask, controlling the reaction temperature at 38-40 ℃ and reacting for 90-180 min to obtain a compound shown as a formula I:

m is an integer, and is a whole number, and M is more than or equal to 3 and less than or equal to 6.

In some embodiments of the invention, the step of chain extension further comprises: b2: adding mixed solution of dihydric alcohol and organic solvent into the reaction solution obtained in the step B1 to carry out chain extension, controlling the reaction temperature to be 42-45 ℃ and reacting for 6-13 h to obtain a compound shown as a formula II:

in some embodiments of the invention, the step of chain extension further comprises: b2: adding mixed solution of dihydric alcohol and organic solvent into the reaction solution obtained in the step B1 to carry out chain extension, controlling the reaction temperature to be between-5 and 0 ℃ and reacting for 2 to 6 hours to obtain a compound shown as a formula III:

wherein R is any one of the following structures:

r ₁ is any one of the following structures:

In some embodiments of the invention, the polyol comprises at least one of glycerol, trimethylolpropane, pentaerythritol, xylitol, and sorbitol.

In some embodiments of the invention, the glycol monomer comprises at least one of 1, 2-hexanediol, 1, 6-hexanediol, 1, 2-butanediol, neopentyl glycol, 1, 8-octanediol, and diethanolamine.

In the invention, when dihydric alcohol is selected as two or more than two of 1, 2-hexanediol, 1, 6-hexanediol, 1, 2-butanediol, neopentyl glycol and 1, 8-octanediol, the finally obtained chain extender is a compound chain extender with active groups containing primary hydroxyl groups and secondary hydroxyl groups, and the number of active groups of each branched core is the same, but the activity of the active groups on the same branched core is different or the activity of the active groups among different branched cores is different. The structure of the product is more abundant, and the comprehensive performance is more excellent.

In some embodiments of the present invention, the chain extension further comprises a finishing step, the finishing step comprising: and (3) stirring 30-40 parts of diethylene glycol butyl ether and 500-520 parts of deionized water at a high speed for 30-45 min under the condition of 300r/min to obtain the polyurethane thickener with the asymmetric branched structure, wherein the solid content of the polyurethane thickener is 19-21%.

In a third aspect the present invention provides the use of an asymmetrically branched polyurethane thickener with multiple arms in the field of industry.

Drawings

The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:

FIG. 1 shows the aqueous solution properties of comparative example 5 of the present invention.

Detailed Description

The conception and the technical effects produced by the present invention will be clearly and completely described in conjunction with the embodiments below to fully understand the objects, features and effects of the present invention. It is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present invention based on the embodiments of the present invention.

Example 1

The preparation of the asymmetric branched polyurethane thickener with multiple arms is shown in the table 1, and the specific process is as follows:

s1: firstly, 133.2g PEG6000 and 0.085g industrial wet-process purified phosphoric acid (85% phosphoric acid) are added into a reaction container, the temperature of the system is raised to 120-125 ℃, vacuum dehydration is carried out for 2h, when the water content of the system is less than 300ppm, the system is cooled to 65-70 ℃ under the protection of nitrogen;

S2: firstly, slowly dripping a DMF solution of HDI into a reaction container, adding organic bismuth after dripping, and reacting at 80 ℃ for 3.5 hours to obtain a linear structure polyurethane prepolymer with isocyanate groups at two ends;

S3: carrying out an active semi-end capping reaction on the polyurethane thickener prepolymer obtained in the step S2, an end capping agent and a part of organic solvent, adding hexadecanol, heating the reaction system in the step S2 to 90 ℃ for reacting for 100min, and obtaining a linear structure polyurethane thickener branched arm with a single arm and a higher polyether chain segment;

S4: adding 40gDMF of solution into a reactor, diluting the materials in the step S3, and cooling the reaction system in the step S3 to 55 ℃; and then slowly dropwise adding a DMF solution of hydrophobic pentaol into the reactor, uniformly stirring, heating to 60 ℃, and carrying out heat preservation reaction for 4 hours to obtain the polyurethane thickener molecule with the five-arm asymmetric branched structure.

S5: and (3) stirring the polyurethane thickener molecules with the five-arm asymmetric branched structure with 30.8g of diethylene glycol butyl ether and deionized water at a high speed for 30-45 min under the condition of 300r/min to obtain the polyurethane thickener product with the five-arm asymmetric branched structure, wherein the solid content of the polyurethane thickener product is 19-21%.

The preparation method of the hydrophobic penta-alcohol comprises the following steps:

B1. firstly, 6.77g of xylitol is dissolved by 80g of hot DMF solution and then is put into a reactor, the system is heated to 38 ℃ under the protection of nitrogen, 50.13g of IPDI solution is slowly added into the reactor, 0.20g of organic bismuth is added after the addition is finished, and reflux reaction is carried out for 2.5 hours at 38-40 ℃ to obtain branched polyurethane prepolymer containing terminal isocyanate groups.

B2. and (3) heating the system in the step (B1) to 42 ℃, adding 26.30g of DMF (dimethyl formamide) solution of 1, 2-hexanediol, and carrying out reflux reaction for 11h at 42-45 ℃ under the protection of nitrogen to obtain hyperbranched polyurethane containing five terminal hydroxyl groups, namely hydrophobic penta-alcohol.

The specific amounts of the materials are shown in Table 1.

Example 2

S2: carrying out active prepolymerization reaction on Hexamethylene Diisocyanate (HDI) and part of organic solvent and part of polymerization catalyst; firstly, slowly dripping an N-methylpyrrolidone solution of HDI into a reaction container, adding organic bismuth after dripping, and reacting at 80 ℃ for 3.5 hours to obtain a polyurethane prepolymer with a linear structure and double ends containing isocyanate groups;

s3: and (3) carrying out an active semi-end capping reaction on the polyurethane thickener prepolymer obtained in the step (S2) and a semi-end capping agent as well as part of organic solvent. After hexadecanol is added, the reaction system in the step S2 is heated to 90 ℃ for reaction for 100min, and a linear structure polyurethane thickener branched arm with a single arm and a higher polyether chain segment is prepared;

S4: adding 60g of N-methyl pyrrolidone solution into a reactor, diluting the material in the step S3, and cooling the reaction system in the step S3 to 55 ℃; slowly dripping the N-methyl pyrrolidone solution of the hydrophobic hexaol into the reactor, uniformly stirring, heating to 65 ℃, and carrying out heat preservation reaction for 5 hours to obtain the polyurethane thickener molecule with the six-arm asymmetric branched structure.

S5: and (3) stirring the polyurethane thickener molecules with the six-arm asymmetric branched structure with 30.8g of dipropylene glycol monobutyl ether and deionized water at a high speed for 30-45 min under the condition of 300r/min to obtain the polyurethane thickener product with the six-arm asymmetric branched structure and the solid content of 19-21%.

The preparation method of the hydrophobic hexaol comprises the following steps:

B1. Firstly, 8.11g of sorbitol is dissolved by 80g of hot N-methylpyrrolidone solution and then is put into a reactor, the temperature of the system is raised to 39 ℃ under the protection of nitrogen, 59.58g of IPDI solution is slowly added into the reactor, 0.15g of dibutyltin dilaurate DBDTL is added after the addition, and reflux reaction is carried out for 2.5 hours at 39-40 ℃ to obtain the branched polyurethane prepolymer containing six-end isocyanate groups.

B2. And (3) heating the system in the step (B1) to 42 ℃, adding 31.56g of DMF (dimethyl formamide) solution of 1, 2-hexanediol, and carrying out reflux reaction for 13h at 42-45 ℃ under the protection of nitrogen to obtain hyperbranched polyurethane containing six hydroxyl ends, namely hydrophobic hexaol.

The specific amounts of the materials are shown in Table 1.

Example 3

S1: firstly, 133.2g PEG6000 and 0.085g industrial wet-process purified phosphoric acid (85% phosphoric acid) are added into a reaction container, the temperature of the system is raised to 120-125 ℃, the vacuum dehydration is carried out for 2 hours, and when the water content of the system is less than 300ppm, the system is cooled to 65-70 ℃ under the protection of nitrogen;

S2: carrying out active prepolymerization reaction on hexamethylene diisocyanate, partial organic solvent and partial polymerization catalyst, slowly dripping DMF solution of HDI into a reaction vessel, adding organic bismuth after dripping, and reacting at 80 ℃ for 3.5 hours to obtain linear polyurethane prepolymer with isocyanate at two ends;

S4: firstly, putting 50gDMF of solution into a reactor, diluting the material in the step (4), and cooling the reaction system in the step (4) to 55 ℃; and slowly dripping a DMF solution of hydrophobic octal into the reactor, uniformly stirring, maintaining the temperature at 55-60 ℃, and carrying out heat preservation reaction for 5 hours to obtain the polyurethane thickener molecule with the octal asymmetric branched structure.

S5: and (3) stirring the polyurethane thickener molecules with the eight-arm asymmetric branched structure with 15.8g of diethylene glycol butyl ether, 15.4g of dipropylene glycol monobutyl ether and 498.9-501.9 g of deionized water at a high speed for 30-45 min under the condition of 300r/min to obtain the polyurethane thickener product with the eight-arm asymmetric branched structure, wherein the solid content of the polyurethane thickener product is 19-21%.

The preparation method of the hydrophobic octal comprises the following steps:

B1. Firstly, 6.05g of pentaerythritol is dissolved by 85g of hot DMF solution and then is put into a reactor, the temperature of the system is raised to 38 ℃ under the protection of nitrogen, 39.74g of IPDI solution is slowly added into the reactor, 0.12g of organic bismuth is added after the addition is finished, and reflux reaction is carried out for 2.5 hours at 38 ℃ to obtain branched polyurethane prepolymer containing terminal isocyanate groups.

B2. Placing the reaction system in the step B1 in an ice salt bath, controlling the temperature in the reaction system to be-5 ℃ to-2 ℃, and slowly dropwise adding 18.66g of DMF solution of diethanolamine for 1-1.5 h; and (3) continuously reacting for 3 hours at the temperature of minus 5 ℃ to 5 ℃ in an ice salt bath system to obtain the hyperbranched polyurethane containing eight hydroxyl ends, namely the hydrophobic octanol.

The specific amounts of the materials are shown in Table 1.

Example 4

s1: firstly, 128.8g PEG4000 and 0.12g industrial wet-process purified phosphoric acid (85% phosphoric acid) are added into a reaction container, the system is heated to 125 ℃, and is dehydrated in vacuum for 2.5h, when the water content of the system is less than 300ppm, the system is cooled to 60 ℃ under the protection of nitrogen;

S2: carrying out active prepolymerization reaction on isophorone diisocyanate, partial organic solvent and partial polymerization catalyst; firstly, slowly dripping DMAC solution of IPDI into a reaction container, uniformly stirring for 30min at 60 ℃, then adding dibutyl tin dilaurate, heating the system to 75 ℃ for reaction for 2h, and obtaining a linear polyurethane prepolymer with isocyanate at two ends;

S3: cooling the reaction system in the step S2 to 60-65 ℃, adding 20g of DMAC solution of dimethylolpropionic acid, and carrying out linear grafting on the DMAC solution and the reaction stock solution in the step S2, wherein the main chain contains a linear polyurethane thickener intermediate with a strong hydrophilic structure (i.e. an ionizable group);

S4: carrying out active semi-end capping reaction on the reaction stock solution obtained in the step S3, a semi-end capping agent and part of organic solvent; after hexadecanol is added, the reaction system in the step S3 is heated to 85 ℃ for reaction for 150min, and the linear structure polyurethane thickener branched arm with a single arm and higher polyether chain segments is prepared.

S5: firstly, putting 40gDMAC of solution into a reactor, diluting the materials in the step S4, and cooling the reaction system in the step S4 to 60 ℃; and slowly dripping the DMAC solution of the hydrophobic dodecanol into the reactor, uniformly stirring, heating to 65 ℃, and carrying out heat preservation reaction for 5 hours to obtain polyurethane thickener molecules with twelve arms and asymmetric branched structures.

S6, stirring the polyurethane thickener with the twelve-arm asymmetric branched structure with 15.6g of diethylene glycol monobutyl, 15.4g of dipropylene glycol monobutyl ether and 498.5-502.5 g of deionized water at a high speed of 300r/min for 30-45 minmin to obtain the polyurethane thickener product with the twelve-arm asymmetric branched structure and the solid content of 19-21%.

The preparation method of the hydrophobic dodecanol comprises the following steps:

B1. firstly, 8.11g of sorbitol is dissolved by 60g of hot DMAC solution and then is put into a reactor, the temperature of the system is raised to 38 ℃ under the protection of nitrogen, 60.02g of IPDI solution is slowly added into the reactor, 0.12g of dibutyltin dilaurate is added after the addition is finished, and reflux reaction is carried out for 3 hours at 38-40 ℃ to obtain branched polyurethane prepolymer containing terminal isocyanate groups.

B2. Placing the reaction system in the step (6.2) in an ice salt bath, controlling the temperature in the reaction system to be-5-0 ℃, slowly dropwise adding 28.04g of DMF solution of diethanolamine, and finishing dropwise adding for 1.5-2 hours; and (3) continuously reacting for 6 hours at the temperature of minus 5 ℃ to 0 ℃ in an ice salt bath system to obtain hyperbranched polyurethane containing twelve terminal hydroxyl groups, namely hydrophobic dodecanol.

The specific amounts of the materials are shown in Table 1.

TABLE 1 amounts of the components in the examples

Comparative example 1 is commercially availableThe G-400 polyurethane rheological agent has a solid content of 20%, is produced by Anhui Guangcheng New Material technology Co., ltd, is an associated polyurethane thickener, and is mainly applied to the field of industrial coating.

Comparative example 2 is a side long chain alkyl modified "comb" associative polyurethane thickener prepared according to example 3 of chinese patent No. CN112961318 a.

Comparative example 3 is a star-structured polyurethane thickener prepared according to example 2 of chinese patent No. CN112831010 a.

Comparative example 4 is a five arm branched structure polyurethane thickener made according to table 2 below.

Comparative example 5 is a six arm branched structure polyurethane thickener made according to table 2 below.

TABLE 2 dosing of the components of comparative examples 4,5

Test examples

This test example tests the properties of polyurethane thickeners prepared in the examples and comparative examples. The results are reported in tables 3-5 below and in FIG. 1.

2 Parts of the samples 10g and 16g of example 1 with 19-21% solids content were taken, deionized water was added to a total of 136g, and stirred until completely dispersed in a pure water system. The addition amount is as follows: thickener solids content sampled amount/total weight = 1.5wt% and 2wt%; taking two samples of comparative example 4, preparing an aqueous solution having the same concentration as example 1, namely 1.5wt% and 2wt%; the test temperature was 25℃and the rotation rate was 6r/min, the measurement range mPa _· s, and the viscosity of the aqueous solution was measured by a rotational viscometer, and the data obtained are shown in Table 3.

TABLE 3 Properties of polyurethane thickener

Table 3 illustrates that the five-arm-containing asymmetric branched polyurethane thickener prepared in this example 1 achieves better thickening efficiency at lower thickener addition levels. And at the same addition amount, the thickening performance of this example was excellent compared to comparative example 4, which also has a five-arm branched structure polyurethane thickener.

4 Parts of the sample of example 2 with 19-21% of solid content are respectively 10g, 14g, 18g and 22g, deionized water is respectively added to 136g of total amount, and the mixture is stirred until the mixture is completely dispersed in a pure water system. The addition amount is as follows: thickener solids content sampled amount/total weight = 1.5wt%, 2wt%, 2.5wt% and 3wt%; taking 4 parts of the sample of comparative example 5, preparing an aqueous solution having the same concentration as example 5, namely 1.5wt%, 2wt%, 2.5wt% and 3wt%; the test temperature was 25℃and the rotation rate was 6r/min, the measurement range mPa _· s, and the viscosity of the aqueous solution was measured by a rotational viscometer, and the results were shown in Table 4 and FIG. 1.

Here, the aqueous solution viscosity of comparative example 5 was not measured, and the aqueous solution properties are shown in FIG. 1.

TABLE 4 Properties of polyurethane thickener

Table 4 illustrates that the six-arm-containing asymmetric branched polyurethane thickener prepared in this example 2 achieves better thickening efficiency at lower thickener addition levels. FIG. 1 shows the "standing water separation" phenomenon of the aqueous solution of comparative example 5 at different concentrations. It was demonstrated that at the same amount of addition, this example 2 not only has good thickening performance but also has improved water bleeding resistance, compared to comparative example 5, which also has a six-arm branched polyurethane thickener.

30G of each of the samples of examples 3 and 4 having a solid content of 19 to 21% was taken, deionized water was added to a total of 120g and 150g, respectively, and stirred until completely dispersed in the pure water system. The addition amount is as follows: thickener solids content 30/total weight = 5wt% and 6wt%; taking 2 parts of the samples of comparative example 1, comparative example 2 and comparative example 3, preparing aqueous solutions having the same concentration as example 3 and example 4, namely 5wt% and 6wt%; the test temperature was 25℃and the rotation rate was 6r/min, the measurement range mPa _· s, and the viscosity of the aqueous solution was measured by a rotational viscometer, and the data were shown in Table 5.

TABLE 5 Properties of polyurethane thickener

Table 5 illustrates that the polyurethane thickeners prepared in examples 3 and 4 having a "multi-arm asymmetric branched structure" achieved better thickening efficiency at lower thickener addition levels. And at the same addition amount, the thickening performance of this example was excellent relative to comparative examples 1,2 and 3.

The asymmetric branched polyurethane thickener with multiple arms synthesized by the invention has three or more hydrophobic long chains, can form a more stable hydrophobic association network structure in a water-based system, reduces the fluidity of the water-based system, and has stronger thickening performance and better stability compared with the traditional linear polyurethane thickener.

In the invention, the asymmetric branched polyurethane thickener with multiple arms has adjustable molecules, and the branched chain extender with different numbers of active groups and different intervals can be selected according to the actual production requirement, so that the structure of branched arms of the polyurethane thickener can be adjusted to obtain the aqueous polyurethane associative thickener which meets the actual requirement; such as with reference to its main application properties of association and de-association, rheology, water solubility, thickening effect, etc. Meanwhile, the molecular weight and the proportion of the hydrophilic and hydrophobic chain segments in the branched chain can be adjusted, so that the viscosity of the obtained polyurethane associative thickener can be adjusted.

In the invention, the active groups on the branched chain extender have larger spacing and different activities, so that asymmetric chain extender branches with different grafting positions can be formed, the structure of the product is more abundant, and the comprehensive performance is more excellent.

In the invention, the polyurethane thickener molecule with a branched structure has a larger central branch skeleton and polyether branches with a longer distance, and the hydrophobic long-chain alkyl group contained in the tail part of each branched chain is matched, so that the polyurethane thickener is favorable for inhibiting the intramolecular association of the thickener and strengthening the intermolecular association of the thickener, and therefore, the thickening capacity of the polyurethane thickener for dilute solution is stronger.

In the invention, a small amount of cosolvent is compounded into the thickener product, so that the dispersion performance of the thickener is improved, and the thickening capacity of the thickener is hardly negatively influenced.

The water-based polyurethane thickener with the branched chain extender as a branching point has higher thickening efficiency, does not sacrifice the water dispersibility, and combines the balance of the water solubility and the thickening effect of the polyurethane thickener.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present invention. Furthermore, embodiments of the invention and features of the embodiments may be combined with each other without conflict.

Claims

1. An asymmetric branched polyurethane thickener with multiple arms, which is characterized in that the preparation raw materials comprise: diisocyanate, polyethylene glycol, branched chain extender, end capping agent and polymerization catalyst;

The branched chain extender is prepared from the following raw materials: diisocyanate, polyol, diol and polymerization catalyst;

The polymerization catalyst of the branched chain extender and the polymerization catalyst of the asymmetric branched polyurethane thickener having multiple arms are the same or different.

2. The asymmetrically branched polyurethane thickener with multiple arms according to claim 1, wherein the preparation raw material of the asymmetrically branched polyurethane thickener with multiple arms further comprises: hydrophilic linear chain extenders;

3. The asymmetrically branched polyurethane thickener with multiple arms according to claim 1, wherein the preparation raw material of the asymmetrically branched polyurethane thickener with multiple arms further comprises: a cosolvent;

4. The asymmetrically branched polyurethane thickener with multiple arms according to claim 1, wherein said capping agent comprises at least one of a higher alcohol and an alcohol polyoxyethylene ether.

5. The asymmetrically branched polyurethane thickener with multiple arms according to claim 1, wherein said polymerization catalyst comprises: at least one of dibutyltin dilaurate, stannous octoate, organic bismuth and triethylamine.

6. The asymmetrically branched polyurethane thickener with multiple arms according to claim 1, wherein the preparation raw material of the asymmetrically branched polyurethane thickener with multiple arms further comprises: an organic solvent;

the organic solvent includes at least one of acetone, butanone, N-methylpyrrolidone, N-ethylpyrrolidone, N-Dimethylacetamide (DMAC) and N, N-Dimethylformamide (DMF).

7. A process for the preparation of an asymmetrically branched polyurethane thickener with multiple arms according to any one of claims 1 to 6, comprising the steps of:

A2: the mother solution obtained in the step A1 reacts with a blocking agent to obtain a reaction stock solution;

a3: and (3) mixing the reaction stock solution obtained in the step (A2) with a branched chain extender for reaction.

8. The method of claim 7, wherein the branched chain extender is prepared by a process comprising: and (3) chain-extending the diisocyanate, the polyol and the polymerization catalyst, and then reacting with the dihydric alcohol.

9. Use of the asymmetrically branched polyurethane thickener with multiple arms according to any of claims 1 to 6 in industrial fields.