Polyurethane thickening agent and preparation method thereof

Abstract

The invention relates to a polyurethane thickening agent and a preparation method thereof. The preparation method comprises the following steps: firstly, carrying out polymerization reaction on diisocyanate and polyether to obtain a corresponding prepolymer containing a branched chain, and then, carrying out reaction on the prepolymer and corresponding alcohol or amine containing an alkyl chain to obtain the polyurethane thickening agent. According to the thickening agent, an allophanate chain segment is introduced to a long chain of polyurethane, so that the thickening performance is remarkably improved, and the thickening agent has excellent salt resistance and can still keep a stable thickening effect even in a salt-containing system. The preparation method is simple and convenient in process, mild in condition and relatively low in cost. In addition, the product does not contain tin compounds, is low in VOC content and has the characteristic of environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of thickener technology, and in particular to a polyurethane thickener and its preparation method. Background Technology

[0002] Polyurethane has long been widely used in many fields due to its highly designable structure and diverse properties. By selecting raw materials and their stoichiometric ratios, polyurethanes with different structures can be obtained, resulting in polyurethanes with different physicochemical properties. One important application is as a thickener, which is widely used to increase the viscosity of water-based preparations, such as in cosmetics, human and animal nutrition, pharmaceuticals, detergents, coatings, and inks.

[0003] Nonionic polyurethane associative thickeners, commonly abbreviated as HEUR, are high-performance synthetic thickeners. Their main molecular chain is composed of urethane bonds (-NH-COO-) formed by the reaction of isocyanate and polyol. These urethane bonds endow the molecular chain with a certain degree of flexibility. HEUR molecules have hydrophobic groups (such as long-chain alkanes) at both ends or on the side chains. In aqueous systems, these hydrophobic groups aggregate through hydrophobic interactions, forming a reversible three-dimensional network structure. They can also associate with hydrophobic regions on the surfaces of emulsion particles and pigment particles. Because the molecular chain does not contain ionic groups (such as carboxyl groups or quaternary ammonium salts), its thickening effect is minimally affected by pH and it exhibits good compatibility with various ionic additives.

[0004] Traditional polyurethane thickeners have a structure consisting of a hydrophilic central backbone connected to hydrophobic end groups. This unique amphiphilic structure is key to their thickening effect. The hydrophilic chain is typically composed of polyethylene oxide, which has strong hydrophilicity and can form hydrogen bonds with water molecules, allowing the entire thickener molecule to dissolve or hydrate in aqueous solutions. The hydrophobic groups at both ends are usually long-chain alkanes (such as C44-C ... 12 H 25 -, C 16 H 33 - alkyl aromatic hydrocarbons (such as nonylphenol) or other hydrophobic groups, these hydrophobic end groups are averse to water and tend to aggregate or adsorb onto the hydrophobic surface of dispersed phases such as emulsion particles and pigments. This reversible physical aggregation behavior is called "association", and the chemical bond connecting the hydrophilic and hydrophobic parts is a carbamate bond.

[0005] US4079028 and US4155892 disclose linear polyurethane thickeners. Their preparation process employs a two-step solution-based method catalyzed by dibutyltin dilaurate (DBTL), a catalyst commonly used in polyurethane chemistry. This preparation method requires the use of high molecular weight polyether polyols, special isocyanates (such as long-chain alkyl isocyanates), and surfactants, thus typically resulting in higher costs compared to conventional thickeners. Furthermore, this preparation method necessitates the use of organic solvents (such as methanol and ethylene glycol) to control the viscosity of the reaction system, which may introduce volatile organic compound (VOC) issues or affect storage stability.

[0006] WO9310166A1 describes a polyurethane thickener prepared by reacting a mixture of polyether alcohol and hydroxyl-oxygenated monohydric alcohol with a polyisocyanate in a step-by-step reaction catalyzed by DBTL or diazabicyclooctane, wherein the equivalence ratio of NCO to OH is 0.9:1-1.2:1. These thickeners are commonly used in low-shear applications, such as for adjusting the flow of waterborne latex paints. However, the specific monomeric alcohols used are not readily available chemicals, resulting in higher costs, and the reaction is carried out using organic solvents (such as toluene, MEK, and NMP). Summary of the Invention

[0007] Based on this, the present invention provides a polyurethane thickener and its preparation method. This thickener significantly improves thickening performance by introducing urethane segments into the long chains of polyurethane and exhibits excellent salt resistance, maintaining a stable thickening effect even in salt-containing systems. Its preparation method is simple, mild, and low-cost. Furthermore, this product is free of tin compounds, has low VOC content, and is environmentally friendly.

[0008] First aspect: A polyurethane thickener comprises a polyurethane polymer, said polyurethane polymer comprising a main chain and branches, said main chain containing a hydrophilic group QS, a hydrophobic group A, and a first linking group L, having the structure A-(L-QS). n -LA, where n is any integer from 1 to 10; the branch contains a first linker group L, a second linker group U, a hydrophilic group QS, and a hydrophobic group A, including at least one structure of U-(L-QS). m -LA extension segments, where m is any integer from 1 to 10, each of the extension segments is connected to the first linker group L of the main chain or the first linker group L of the branch chain via the second linker group U, and at least one first linker group L of the main chain is connected to the extension segment; The hydrophilic group QS is a polyether group, the hydrophobic group A is an alkyl or aromatic group with 8 to 30 carbon atoms, the first linking group L contains at least one urethane group and a diisocyanate residue, and the second linking group U is a urea group.

[0009] Specifically, one type of polyurethane polymer includes, for example, the following repeating sequence:

[0010] One molecule consists of two hydrophilic groups QS, three hydrophobic groups A, four first linker groups L and one second linker group U; that is, n=1, m=1, and there is only one extended chain segment.

[0011] The hydrophilic group QS is connected to a first linker L at both ends, the hydrophobic group A is connected to a first linker L, and the second linker U is connected to a first linker L at both ends; the end capping group is the hydrophobic group A.

[0012] It may also include the following chain segment sequences:

[0013] One molecule comprises three hydrophilic groups QS, four hydrophobic groups A, six first linking groups L, and two second linking groups U; that is, n=1, m=1, and has two extended segments, one of which is connected to the first linking group L of the main chain, and the other of which is connected to the first linking group L of the branch chain. Each first linking group L is connected to at most one second linking group U.

[0014] In other embodiments, in order to achieve more association, based on the above structure, the L-QS on the main chain and the L-QS on the side chain can be repeating units in the chain segment. Each first linking group L in the repeating unit on the main chain can be connected to an extended chain segment, and the first linking group L in each extended chain segment can be connected to another extended chain segment, thereby further improving the thickening performance.

[0015] This invention introduces a second linking group U containing a urea-formate segment as the starting segment of a branch on the main chain of a polyurethane polymer, further connecting a hydrophilic group QS and a hydrophobic group A to form a polyurethane thickener with side chains. On one hand, through the comb-like / branch-like branched structure, the hydrophobic group A in this structure can further participate in association to form a three-dimensional network structure, increasing the crosslinking density of the polyurethane thickener. The highly crosslinked network restricts the free movement of the polyurethane thickener. On the other hand, the thickener of this invention not only combines the main chain and branches of the polyurethane thickener but also forms hydrogen bonds. Under the synergistic effect of association and hydrogen bonding, the viscosity of the system under low shear is improved, giving the polyurethane thickener superior rheological modification capabilities.

[0016] This invention presents a novel waterborne polyurethane thickener that, while retaining the advantages of traditional products, achieves key breakthroughs in thickening efficiency and rheological properties, significantly outperforming mature products on the market. Its main functions include highly efficient thickening of waterborne systems and providing precise rheological control, rapidly increasing viscosity, and enhancing storage stability and anti-settling properties. Simultaneously, its unique rheological characteristics optimize application performance, imparting excellent leveling and fullness to coatings, providing a superior solution for high-end waterborne coatings, inks, and adhesives.

[0017] Specifically, the present invention has the following characteristics: Stronger thickening effect: At the same addition amount, the polyurethane thickener prepared by this invention provides a final viscosity that is significantly higher than that of existing products, which means that less addition amount can be used to achieve the same viscosity requirements, resulting in higher efficiency.

[0018] Improved thixotropy: The polyurethane thickener prepared in this invention imparts a more ideal thixotropic structure to the system. In a static state, the system maintains high viscosity, effectively preventing the sedimentation and water separation of fillers and pigments; when subjected to shear forces (such as during application, mixing, brushing, or spraying), the viscosity rapidly decreases, resulting in extremely smooth operation, a light and refreshing application feel, and effective prevention of sagging; after the shear force is eliminated, the viscosity quickly recovers, ensuring the paint film has good leveling and fullness.

[0019] As a preferred embodiment, the hydrophobic group A is a branched or unbranched alkyl or aromatic group.

[0020] As a preferred embodiment, the hydrophobic group A is an alkyl or aromatic group with 12 to 30 carbon atoms. Within a certain range, the thickening effect of the thickener will be better as the number of carbon atoms increases.

[0021] As a preferred embodiment, the polyurethane polymer comprises the following structure

[0022] Where y is any positive integer from 1 to 10, z is any positive integer from 1 to 10, R1 is an alkyl or aromatic group with 8 to 30 carbon atoms, R is a diisocyanate residue, and X refers to an O atom or an NH group.

[0023] The second aspect: A method for preparing the polyurethane thickener described in the first aspect includes the following steps: A prepolymer is obtained by mixing polyether glycol, diisocyanate and carboxylate with a molecular weight of 4000~12000 and keeping it at 70~90℃ for 0.5~1.5h. An alcohol or amine containing the hydrophobic group A is added to the prepolymer, and the mixture is kept at 70-90°C for 0.5-1.5 hours to obtain the polyurethane thickener.

[0024] The preparation method of the present invention is as follows:

[0025] First, diisocyanate undergoes a polymerization reaction with polyether to obtain a prepolymer containing branched chains, which then reacts with an alcohol or amine containing alkyl chains to obtain the polyurethane thickener of the present invention.

[0026] It has the following advantages: Lower production costs: Through optimized synthesis routes and raw material selection, the overall production cost of polyurethane thickeners is significantly reduced, providing customers with higher cost-effectiveness and stronger market competitiveness.

[0027] Simple process operation: The polyurethane thickener prepared by this invention has good water dispersibility and compatibility. No special equipment or complicated addition procedures are required in the production process. It is easy to disperse and does not easily produce gel particles, which greatly simplifies the production process, improves production efficiency, and reduces production risks caused by improper operation.

[0028] Strong potential for industrial production: The polyurethane thickener of this invention has a stable synthesis process, mild reaction conditions, no particularly demanding requirements on production equipment, and readily available raw materials, ensuring a stable supply chain. These characteristics make it fully capable of large-scale, continuous industrial production, guaranteeing batch-to-batch stability of product quality and meeting substantial market demand.

[0029] As a preferred embodiment, the total amount of the polyether diol and the alcohol or amine containing the hydrophobic group A accounts for 60-70% of the total amount of the reactants, and the molar ratio of the polyether diol to the diisocyanate is 1:1.5-2.5.

[0030] As a preferred embodiment, the polyurethane thickener further includes isocyanate, with the isocyanate content not exceeding 0.05 wt%. Excessive unreacted isocyanate content can affect the associative network of the polyurethane polymer, thereby impacting the thickening effect.

[0031] As a preferred embodiment, the carboxylate includes at least one of bismuth carboxylate, ferric carboxylate, titanium carboxylate, zinc carboxylate, and aluminum carboxylate.

[0032] Using a metal carboxylate as a catalyst in the preparation method of this invention allows for the in-situ formation of urea-formate bonds, thus generating branched segments of the polyurethane. These branched segments give the polyurethane obtained by this method a comb-like / dendritic structure, which can form a three-dimensional network structure resulting in a higher crosslinking density. This network restricts the free movement of latex particles, thereby increasing the viscosity of the system at low shear rates. Therefore, the polyurethane thickener obtained by this method has superior rheological modification capabilities.

[0033] Furthermore, the polyurethane thickener formulation prepared by this invention completely eliminates harmful heavy metals such as organotin compounds that may be present in traditional thickeners, complies with increasingly stringent global environmental regulations (such as REACH, EPA, etc.), and is safer for producers and users and more environmentally friendly.

[0034] As a preferred embodiment, the diisocyanate includes at least one of 1,6-hexanediisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), toluene diisocyanate (TDI), and 4,4-diphenylmethane diisocyanate (MDI). Attached Figure Description

[0035] Figure 1 Viscosity test curves of the polyurethane thickener prepared in Example 1 and the competing thickener; Figure 2 The graph shows the thixotropic value test curves of the polyurethane thickener prepared in Example 1 and the competing thickener. Detailed Implementation

[0036] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0037] A polyurethane thickener comprises a polyurethane polymer, said polyurethane polymer comprising a main chain and branches, said main chain containing a hydrophilic group QS, a hydrophobic group A, and a first linking group L, having the structure A-(L-QS). n -LA, where n is any integer from 1 to 10; the branch contains a first linker group L, a second linker group U, a hydrophilic group QS, and a hydrophobic group A, including at least one structure of U-(L-QS). m -LA extension segments, where m is any integer from 1 to 10, each of the extension segments is connected to the first linker group L of the main chain or the first linker group L of the branch chain via the second linker group U, and at least one first linker group L of the main chain is connected to the extension segment; The hydrophilic group QS is a polyether group, the hydrophobic group A is an alkyl or aromatic group with 8 to 30 carbon atoms, the first linking group L contains at least one urethane group and a diisocyanate residue, and the second linking group U is a urea group.

[0038] Specifically, one of the polyurethane polymers includes the following repeating unit sequence:

[0039] One molecule consists of two hydrophilic groups QS, three hydrophobic groups A, four first linker groups L and one second linker group U; that is, n=1, m=1, and there is only one extended chain segment.

[0040] The hydrophilic group QS is connected to a first linker L at both ends, the hydrophobic group A is connected to a first linker L, and the second linker U is connected to a first linker L at both ends; the end capping group is the hydrophobic group A.

[0041] It may also include the following chain segment sequences:

[0042] One molecule comprises three hydrophilic groups QS, four hydrophobic groups A, six first linking groups L, and two second linking groups U; that is, n=1, m=1, and has two extended segments, one of which is connected to the first linking group L of the main chain, and the other of which is connected to the first linking group L of the branch chain. Each first linking group L is connected to at most one second linking group U.

[0043] In other embodiments, in order to achieve more association, based on the above structure, the L-QS on the main chain and the L-QS on the side chain can be repeating units in the chain segment. Each first linking group L in the repeating unit on the main chain can be connected to an extended chain segment, and the first linking group L in each extended chain segment can be connected to another extended chain segment, thereby further improving the thickening performance.

[0044] Specifically, the polyurethane thickener includes the following structure

[0045] Where y is any positive integer from 1 to 10, z is any positive integer from 1 to 10, R1 is an alkyl or aromatic group with 8 to 30 carbon atoms, and R is a diisocyanate residue.

[0046] A method for preparing a polyurethane thickener includes the following steps: Polyether glycol with a molecular weight of 4000~12000 is heated under vacuum to remove moisture, and then mixed with diisocyanate and carboxylate under an inert gas atmosphere. The mixture is kept at 70~90℃ for 0.5~1.5h to obtain a prepolymer. An alcohol or amine containing a hydrophobic group A is added to the prepolymer, and the mixture is kept at 70-90°C for 0.5-1.5 hours. The reaction is stopped when the isocyanate content is no higher than 0.05 wt%, and a polyurethane thickener is obtained.

[0047] The preparation method of the present invention is as follows:

[0048] The total amount of polyether glycol and alcohols or amines containing hydrophobic group A accounts for 60-70% of the total amount of the reactants, and the molar ratio of polyether glycol to diisocyanate is 1:1.5-2.5. The carboxylate includes at least one of bismuth carboxylate, iron carboxylate, titanium carboxylate, zinc carboxylate, and aluminum carboxylate. The diisocyanate includes at least one of 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), toluene diisocyanate (TDI), and 4,4-diphenylmethane diisocyanate (MDI).

[0049] It should be noted that the substances referred to by the abbreviations in the embodiments of the present invention are: IPDI: Isophorone diisocyanate; HDI: Hexamethylene diisocyanate; HMDI: Dicyclohexylmethane diisocyanate.

[0050] PEG-4000: Polyethylene glycol-4000; PEG-6000: Polyethylene glycol-6000; PEG-8000: Polyethylene glycol-8000.

[0051] DGBE: Diethylene glycol butyl ether; DMEA: N,N-dimethylethanolamine.

[0052] In this embodiment of the invention, PUA-5811 is an acrylic-modified polyurethane emulsion from Guangzhou Guanzhi, with a viscosity of 20~30 mPa·s at 25°C; PA-4000 is an acrylic emulsion from Guangzhou Guanzhi.

[0053] In this embodiment of the invention, the competing thickener is Hemings 299.

[0054] Example 1 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 14.3 g (52.9 mmol) of isomeric octadecyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0055] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 5581mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0056] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 13340mPa·s.

[0057] Example 2 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 10.6 g (52.9 mmol) of isotridecyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0058] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener for dilution. The viscosity of the dispersion was measured to be 2587 mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0059] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 4563mPa·s.

[0060] Example 3 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 12.8 g (52.9 mmol) of isohexadecyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0061] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 4786mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0062] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 10321mPa·s.

[0063] Example 4 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 15.8 g (52.9 mmol) of isomeric eicosyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0064] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 6542mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0065] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 9952mPa·s.

[0066] Example 5 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (26.5 mmol) of PEG-4000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 14.3 g (52.9 mmol) of isomeric octadecyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0067] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 4879 mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0068] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 5621mPa·s.

[0069] Example 6 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (13.3 mmol) of PEG-8000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 14.3 g (52.9 mmol) of isomeric octadecyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0070] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 11573 mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0071] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 8752mPa·s.

[0072] Example 7 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 7.4 g (44.1 mmol) of HDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 14.3 g (52.9 mmol) of isomeric octadecyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0073] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 7831 mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0074] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 6624mPa·s.

[0075] Example 8 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 11.6 g (44.1 mmol) of HMDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 14.3 g (52.9 mmol) of isomeric octadecyl alcohol was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0076] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 8564 mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0077] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 5589mPa·s.

[0078] Example 9 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 9.8 g (52.9 mmol) of n-dodecylamine was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0079] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 9872 mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0080] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 1312mPa·s.

[0081] Example 10 A method for preparing a polyurethane thickener includes the following steps: In a four-necked round-bottom flask equipped with a stirrer, reflux condenser, and nitrogen inlet, 106.25 g (17.7 mmol) of PEG-6000 was heated to 100 °C and dehydrated under vacuum for 4 h. Then, the temperature was lowered to 70 °C, and 9.8 g (44.1 mmol) of IPDI and 0.25 g of bismuth carboxylate were added under a nitrogen atmosphere. The temperature was then raised to 80 °C and held for 1 h. 14.3 g (52.9 mmol) of n-octadecylamine was added to the reaction system, and the reaction was continued at 80 °C for 1 h to obtain a polyurethane thickener.

[0082] 65.3g of DGBE and 130.6g of pure water were added to the polyurethane thickener to dilute it and obtain a thickener dispersion. The viscosity of the dispersion was measured to be 19814 mPa·s using a Brookfield viscometer with rotor No. 4 and 30 revolutions.

[0083] Thickening efficiency test: Take 0.5g of thickener dispersion, add 3g of DGBE and 15g of pure water to dilute, add 100g of PUA-5811, and measure the viscosity of the emulsion after thickening with a Brookfield viscometer at rotor No. 4 and 30 revolutions. The viscosity is 1800mPa·s.

[0084] Viscosity and thixotropic value test The PA-4000 emulsion system used for testing was formulated as follows, by mass percentage: 15% pure water, 80% PA-4000, 0.1-1% 903W defoamer, and the balance being dipropylene glycol methyl ether.

[0085] In the test, the mass of the PA-4000 emulsion system was used as the benchmark, and was calculated as 100%.

[0086] like Figures 1-2 As shown in Table 1, the thickener dispersion prepared in Example 1 and the competitor's thickener were added to two PA-4000 emulsion systems, respectively. The amount added was 0.25% of the mass of the PA-4000 emulsion system. The viscosity and corresponding pH value were measured at different rotation speeds. It can be seen that the thickening effect of the polyurethane thickener prepared in Example 1 of this invention is better than that of the competitor, and the pH is weakly acidic or neutral.

[0087] Subsequently, to ensure the system was in an alkaline environment where the polyurethane thickener would exert its optimal thickening effect, the pH of the emulsion was adjusted to 8-9 by adding 0.3% DMEA. In emulsion formulations, pH is crucial for emulsion stability, thickener efficiency, and preservative activity. Adjusting the pH resulted in an increase in system viscosity, and the polyurethane thickener prepared in Example 1 demonstrated better thickening performance than competing products.

[0088] Next, to assess the "consumption" or "damage" of the thickening network by the powder, 3% of matting agent E-1011 was added to the emulsion. A slight decrease in pH and viscosity was observed, with the viscosity of the emulsion in Example 1 showing a more significant reduction compared to the competing product. At this point, 0.3% DMEA was further added to observe whether the viscosity could partially or completely recover, determining whether the damage caused by the matting agent was physical adsorption (potentially reversible) or irreversible. If the viscosity recovered, it indicated that the negative impact of the matting agent could be compensated for by adjusting the formulation (such as adding a suitable surfactant or co-solvent). Experimental results showed that the viscosity of both Example 1 and the competing product increased significantly, with the increase in viscosity of Example 1 being more pronounced.

[0089] Finally, 20% water was added to dilute the system concentration. The viscosity of Example 1 was observed to be superior to that of the competing products. The polyurethane thickener prepared in Example 1 of this invention has good stability.

[0090] Table 1. Comparison of the polyurethane thickener prepared in Example 1 with competing products.

[0091] The above embodiments are merely illustrative of several implementations of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the invention patent. For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A polyurethane thickener, characterized in that, The invention includes a polyurethane polymer comprising a main chain and branches, wherein the main chain contains a hydrophilic group QS, a hydrophobic group A, and a first linking group L, having a structure of A-(L-QS). n -LA, where n is any integer from 1 to 10; the branch contains a first linker group L, a second linker group U, a hydrophilic group QS, and a hydrophobic group A, including at least one structure of U-(L-QS). m -LA extension segments, where m is any integer from 1 to 10, each of the extension segments is connected to the first linker group L of the main chain or the first linker group L of the branch chain via the second linker group U, and at least one first linker group L of the main chain is connected to the extension segment; The hydrophilic group QS is a polyether group, the hydrophobic group A is an alkyl or aromatic group with 8 to 30 carbon atoms, the first linking group L contains at least one urethane group and a diisocyanate residue, and the second linking group U is a urea group.

2. The polyurethane thickener according to claim 1, characterized in that, The hydrophobic group A is an unbranched alkyl or aromatic group.

3. The polyurethane thickener according to claim 2, characterized in that, The hydrophobic group A is an alkyl or aromatic group with 12 to 30 carbon atoms.

4. The polyurethane thickener according to claim 1, characterized in that, The polyurethane polymer comprises the following structure: Where y is any positive integer from 1 to 10, z is any positive integer from 1 to 10, R1 is an alkyl or aromatic group with 8 to 30 carbon atoms, R is an aliphatic or aromatic group, and X refers to an O atom or an NH group.

5. The method for preparing the polyurethane thickener according to any one of claims 1 to 4, characterized in that, Includes the following steps: A prepolymer is obtained by mixing polyether glycol, diisocyanate and carboxylate with a molecular weight of 4000~12000 and keeping it at 70~90℃ for 0.5~1.5h. An alcohol or amine containing the hydrophobic group A is added to the prepolymer, and the mixture is kept at 70-90°C for 0.5-1.5 hours to obtain the polyurethane thickener.

6. The method for preparing the polyurethane thickener according to claim 5, characterized in that, The total amount of the polyether diol and the alcohol or amine containing the hydrophobic group A accounts for 60-70% of the total amount of the reactants, and the molar ratio of the polyether diol to the diisocyanate is 1:1.5-2.

5.

7. The method for preparing the polyurethane thickener according to claim 5, characterized in that, The polyurethane thickener also includes isocyanate, and the isocyanate content is not higher than 0.05 wt%.

8. The method for preparing the polyurethane thickener according to claim 5, characterized in that, The carboxylate includes at least one of bismuth carboxylate, ferric carboxylate, titanium carboxylate, zinc carboxylate, and aluminum carboxylate.

9. The method for preparing the polyurethane thickener according to claim 5, characterized in that, The diisocyanate includes at least one selected from 1,6-hexanediisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, and 4,4-diphenylmethane diisocyanate.

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