Dendritic macromolecular dispersant and preparation method and application thereof

Abstract

The present invention belongs to the technical field of polymer polyols, and specifically relates to a dendritic macromolecular dispersant and a preparation method and application thereof. The preparation method comprises: (1) using sorbitol and alkylene oxide to carry out polymerization reaction to obtain a low molecular weight polyether; (2) esterifying the low molecular weight polyether with 2,2-dimethylol propionic acid to obtain a polyester ether intermediate; (3) polymerizing the polyester ether intermediate with alkylene oxide again to obtain a dendritic polyether; (4) prepolymerizing the dendritic polyether with an unsaturated isocyanate to obtain a dendritic macromolecular dispersant. The present invention can reduce the viscosity of the macromolecular dispersant and the synthesized polymer polyol on the one hand by optimizing the branched structure of the macromolecular dispersant, and on the other hand can enhance its anchoring ability to polymer particles, thereby improving the stability of styrene-acrylonitrile copolymer particles in the polymer polyol.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer polyols, and in particular relates to a dendritic macromolecular dispersant and a preparation method and application thereof. Background Art

[0002] Polyurethane soft foam materials often use polymer particles in polymer polyols (POP) to improve their open porosity, enhance hardness and increase load-bearing capacity. The polymer in POP generally refers to copolymers or autopolymers formed by free radical polymerization of vinyl monomers such as styrene and acrylonitrile, and also includes polymers obtained by graft polymerization on polyether segments. As the polymer particle content (i.e. solid content) increases, the viscosity of POP will increase significantly. In addition, POP may also have problems such as polymer particle sedimentation during long-term storage, which brings many restrictions to downstream applications. Therefore, how to develop POP with excellent dispersion properties and high solid content and low viscosity characteristics has become a hot spot and difficulty in research in this industry.

[0003] In the preparation process of POP, macromolecular dispersants play a vital role. Their unique amphiphilic structure can bring excellent dispersing properties to POP. Traditional macromolecular dispersants usually rely on maleic anhydride to provide unsaturated structures, but the POP synthesized in this way often has a high viscosity. Once water is added, the viscosity will rise rapidly.

[0004] Chinese patent CN111154095A discloses a silicon-modified macromolecular monomer stabilizer, its preparation method and use. The stabilizer is synthesized by using silicon-modified macromolecular monomers to improve the viscosity problem of maleic anhydride macromonomers and improve the hydrophilicity of POP. However, its raw materials and preparation costs are relatively high. Chinese patent CN118562120A discloses a dispersant stabilizer, its preparation method and use. First, acrylic acid containing a hydroxyl structure is reacted with isocyanate, and then the isocyanate is further reacted with polyether. The prepared dispersant synthesizes POP with the characteristics of high solid and low viscosity. As the functionality or branched structure of the macromolecular dispersant increases, the viscosity of the macromolecular dispersant decreases, and the dispersibility and storage stability of POP will also increase at the same addition amount. However, organic solvents need to be used in its synthesis process, which is relatively risky. Chinese patent CN112708124A discloses a method for preparing a high-functionality polyether polyol and its application, using oxirane alcohol as a polymerization monomer raw material to increase the functionality of the macromolecular monomer. However, oxirane alcohol has certain toxicity, and the actual production process is subject to many restrictions.

[0005] 2,2-Dihydroxymethylpropionic acid (DMPA) is a common raw material for waterborne polyurethanes. Its unique AB2 structure is very suitable for the synthesis of hyperbranched polymers. For example, Wei., et al. ACS Appl. Polym. Mater. 2021, 3, 3612-3622 reported the successful preparation of hyperbranched polyols with a branching degree of 0.43 by a two-step esterification reaction of DMPA and castor oil. This study not only demonstrated the potential of DMPA in improving the branching degree of polymers through esterification reactions, but also provided new ideas and directions for the development of low-viscosity dispersants and the improvement of POP performance. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a dendritic macromolecular dispersant, which can reduce the viscosity of the macromolecular dispersant and the synthesized polymer polyol by optimizing the branched structure of the macromolecular dispersant, and enhance its anchoring ability to polymer particles, thereby improving the stability of styrene-acrylonitrile copolymer particles in the polymer polyol.

[0007] Another object of the present invention is to provide a preparation method and application of a dendritic macromolecular dispersant.

[0008] The technical solution adopted by the present invention is as follows:

[0009] The preparation method of the dendritic macromolecular dispersant comprises the following steps:

[0010] (1) Using sorbitol as the initiator, the alkylene oxide is polymerized in the presence of a catalyst to obtain a low molecular weight polyether;

[0011] (2) subjecting the low molecular weight polyether obtained in step (1) to an esterification reaction with 2,2-dihydroxymethylpropionic acid in the presence of a catalyst to obtain a polyester ether intermediate;

[0012] (3) subjecting the polyester ether intermediate obtained in step (2) to a polymerization reaction with alkylene oxide under the action of a catalyst to obtain a dendritic polyether;

[0013] (4) The dendritic polyether prepared in step (3) is subjected to a prepolymerization reaction with an unsaturated isocyanate in the presence of a catalyst to obtain a dendritic macromolecular dispersant.

[0014] In the step (1), the catalyst is an alkali metal catalyst; and the number average molecular weight of the low molecular weight polyether is 2490-4050 g / mol.

[0015] In the step (2), the molar ratio of the low molecular weight polyether to 2,2-dihydroxymethylpropionic acid is 1:(0.9-4); the catalyst is one of concentrated sulfuric acid or p-toluenesulfonic acid; and the temperature of the esterification reaction is 130-160°C.

[0016] In the step (3), the catalyst is a DMC catalyst; the number average molecular weight of the dendritic polyether is 11800-19450 g / mol.

[0017] In the steps (1) and (3), the alkylene oxide is one or more of propylene oxide and ethylene oxide; and the polymerization reaction temperature is 100-140°C.

[0018] In the step (4), the unsaturated isocyanate is one of 3-isopropyl-dimethylbenzyl isocyanate, 2-ethyl methylacrylate or ethyl isocyanate acrylate; and the molar ratio of the dendritic polyether to the unsaturated isocyanate is 1:(0.8-1.1).

[0019] In the step (4), the catalyst is a bismuth catalyst or a zinc catalyst; the temperature of the prepolymerization reaction is 70-90°C, preferably 80°C.

[0020] The dendritic macromolecular dispersant is prepared by the above-mentioned preparation method of the dendritic macromolecular dispersant.

[0021] The dendritic macromolecular dispersant is used for the preparation of polymer polyols.

[0022] The preparation method of the polymer polyol comprises the following steps:

[0023] 1) Using a dendritic macromolecular dispersant and an ethylenically unsaturated monomer to react under the action of a chain transfer agent and an initiator to synthesize a pre-reactant;

[0024] 2) The pre-reactant, the basic polyether polyol and the ethylenically unsaturated monomer are reacted under the action of an initiator to obtain a polymer polyol.

[0025] The ethylenically unsaturated monomers are styrene and acrylonitrile.

[0026] The chain transfer agent is one or more of methanol, ethanol, butanol, isopropanol or mercaptan.

[0027] The initiator is one of azobisisobutyronitrile, dimethyl azobisisobutyrate or tert-amyl peroxy 2-ethylhexanoate.

[0028] The basic polyether polyol is a tri-functional soft foam polyether polyol with a number average molecular weight of 3000-5000 g / mol.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The macromolecular dispersant of the present invention has a dendritic structure and a high degree of branching, and can occupy a large dispersion volume in POP, thereby effectively enhancing the anchoring ability of POP particles, thereby improving the dispersibility and filtration performance of POP; at the same time, since the synthesized dendritic macromolecular dispersant has a low viscosity, the prepared POP also exhibits the characteristics of low viscosity;

[0031] (2) In the preparation method of the dendritic macromolecular dispersant described in the present invention, when synthesizing the polyester ether intermediate, the raw material 2,2-dihydroxymethylpropionic acid used is widely available and low in cost; the concentrated sulfuric acid or p-toluenesulfonic acid catalyst used can also be used as a co-catalyst for the synthesis of dendritic polyether, thereby improving its reaction activity. DETAILED DESCRIPTION

[0032] The present invention is further described below with reference to the embodiments, but they do not limit the implementation of the present invention.

[0033] Unless otherwise specified, the raw materials used in the examples and comparative examples are conventional commercially available raw materials, and the process methods used in the examples and comparative examples are conventional methods in the art unless otherwise specified.

[0034] Some of the raw materials used in the examples and comparative examples are described as follows:

[0035] Polyether polyol INOVOL F5631 (number average molecular weight of 3000, functionality of 3) was purchased from Shandong INOVOL New Materials Co., Ltd.;

[0036] Liquid sorbitol, VC grade, was purchased from Shandong Tianli Pharmaceutical Co., Ltd.;

[0037] Solid sorbitol was purchased from Shouguang Zhongrui Biotechnology Co., Ltd.

[0038] Example 1

[0039] The preparation method of the dendritic macromolecular dispersant A comprises the following steps:

[0040] (1) 182 g of solid sorbitol and 12 g of KOH were added to a pressure reactor. The temperature was raised to 100 °C and dehydrated for 6 h. Then, 3900 g of propylene oxide was slowly added to carry out polymerization reaction. The polymerization temperature was 120 ± 20 °C. After the reaction was completed, the internal pressure was kept at 1 h. The monomers were removed in a vacuum for 0.5 h. After the temperature was lowered, 27 g of phosphoric acid and 140 g of water were added for neutralization reaction. Then, 10 g of magnesium aluminum silicate was added for adsorption. The reaction was then dehydrated and dried to obtain a low molecular weight polyether 1 with a number average molecular weight of 4020 g / mol.

[0041] (2) Add 54 g of 2,2-dihydroxymethylpropionic acid and 4 g of concentrated sulfuric acid to 400 g of the low molecular weight polyether 1 obtained in step (1), first heat to 130° C., bubbling with nitrogen for 5 h, then heat to 160° C., evacuate, and continue to react for 4 h to obtain a polyester ether intermediate 1;

[0042] (3) 0.025 g of a modified DMC catalyst was added to 200 g of the polyester ether intermediate 1 obtained in step (2), the temperature was raised to 130° C., dehydrated for 1 h, and then 26 g of propylene oxide was added dropwise to initiate the polymerization reaction. Then, a mixture of 250 g of propylene oxide and 80 g of ethylene oxide was added to continue the polymerization reaction. The polymerization temperature was 120±20° C. After the addition of alkylene oxide, the internal pressure was maintained for 1 h, and the monomer removal was performed for 0.5 h to obtain a dendritic polyether 1 having a number average molecular weight of 11800 g / mol and a viscosity of 1354 mPa·s;

[0043] (4) 1200 g of the dendritic polyether 1 obtained in step (3) was prepolymerized with 20.1 g of 3-isopropyl-dimethylbenzyl isocyanate in the presence of 0.15 g of bismuth neodecanoate. The prepolymerization temperature was 80±10° C. The infrared spectrum recorded the peak at 2261 cm -1 The disappearance of the peak at φ indicates the end point of the reaction, and dendrimer dispersant A is obtained with a viscosity of 1551 mPa·s.

[0044] Example 2

[0045] The preparation method of the dendritic macromolecular dispersant B comprises the following steps:

[0046] (1) The steps are the same as those in Example 1;

[0047] (2) The steps are the same as those in Example 1;

[0048] (3) 0.04 g of modified DMC catalyst was added to 200 g of the polyester ether intermediate 1 obtained in step (2), the temperature was raised to 130° C., dehydrated for 1 h, and then 30 g of propylene oxide was added dropwise to initiate polymerization, and then a mixture of 620 g of propylene oxide and 150 g of ethylene oxide was added to continue polymerization. The polymerization temperature was 120±20° C. After the addition of alkylene oxide, the internal pressure was maintained for 1 h, and the monomer removal was performed for 0.5 h to obtain a dendritic polyether 2 having a number average molecular weight of 19411 g / mol and a viscosity of 1560 mPa·s;

[0049] (4) 1950 g of the dendritic polyether 2 obtained in step (3) was prepolymerized with 15.5 g of 2-ethyl isocyanate of methyl methacrylate in the presence of 0.4 g of zinc neodecanoate. The prepolymerization temperature was 80±10° C. The infrared spectrum recorded the peaks at 2261 cm -1The disappearance of the peak at φ indicates the end point of the reaction, and dendrimer dispersant B is obtained with a viscosity of 1686 mPa·s.

[0050] Example 3

[0051] The preparation method of the dendritic macromolecular dispersant C comprises the following steps:

[0052] (1) The steps are the same as those in Example 1;

[0053] (2) The steps are the same as those in Example 1;

[0054] (3) The steps are the same as those in Example 2;

[0055] (4) 2000 g of the dendritic polyether 2 obtained in step (3) was prepolymerized with 20.1 g of 3-isopropyl-dimethylbenzyl isocyanate in the presence of 0.5 g of zinc neodecanoate. The prepolymerization temperature was 80±10° C. The infrared spectrum recorded the peak at 2261 cm -1 The disappearance of the peak at φ was the end point of the reaction, and the dendrimer dispersant C was obtained with a viscosity of 1765 mPa·s.

[0056] Example 4

[0057] The preparation method of the dendritic macromolecular dispersant D comprises the following steps:

[0058] (1) 260 g of liquid sorbitol and 8 g of KOH were added to a pressure reactor, the temperature was raised to 115°C and dehydrated for 6 hours, and then 2500 g of propylene oxide was slowly added for polymerization reaction. The polymerization temperature was 120±20°C. After the reaction was completed, the internal pressure was kept for 1 hour, and the monomers were removed in a vacuum for 0.5 hour. After the temperature was lowered, 18.5 g of phosphoric acid and 87 g of water were added for neutralization reaction, and then 4.5 g of magnesium aluminum silicate was added for adsorption, followed by dehydration and drying to obtain a low molecular weight polyether 2 with a number average molecular weight of 2490 g / mol.

[0059] (2) Add 21.4 g of 2,2-dihydroxymethylpropionic acid and 4 g of p-toluenesulfonic acid to 400 g of the low molecular weight polyether 2 obtained in step (1), first heat to 130° C., bubbling with nitrogen for 5 h, then heat to 160° C., evacuate, and continue to react for 4 h to obtain a polyester ether intermediate 2;

[0060] (3) 0.04 g of modified DMC catalyst was added to 250 g of the polyester ether intermediate 2 obtained in step (2), the temperature was raised to 130° C., dehydrated for 1 h, and then 40 g of propylene oxide was added dropwise to initiate the polymerization reaction. Then, a mixture of 900 g of propylene oxide and 210 g of ethylene oxide was added to continue the polymerization reaction. The polymerization temperature was 120±20° C. After the addition of alkylene oxide, the internal pressure was maintained for 1 h, and the monomer removal was performed for 0.5 h to obtain a dendritic polyether 3 having a number average molecular weight of 13850 g / mol and a viscosity of 1875 mPa·s;

[0061] (4) 1350 g of the dendritic polyether 3 obtained in step (3) was prepolymerized with 14.1 g of ethyl isocyanate acrylate in the presence of 0.2 g of bismuth neodecanoate. The prepolymerization temperature was 80±10° C. The infrared spectrum recorded the peaks at 2261 cm -1 The disappearance of the peak at φ was the end point of the reaction, and the dendrimer dispersant D was obtained with a viscosity of 2160 mPa·s.

[0062] Comparative Example 1

[0063] The preparation method of the macromolecular dispersant E comprises the following steps:

[0064] (1) The steps are the same as those in Example 1;

[0065] (2) 0.06 g of a modified DMC catalyst was added to 400 g of the low molecular weight polyether 1 obtained in step (1), the temperature was raised to 130° C., dehydrated for 1 h, and then 30 g of propylene oxide was added dropwise to initiate polymerization, and then a mixture of 590 g of propylene oxide and 185 g of ethylene oxide was added to continue polymerization. The polymerization temperature was 120±20° C. After the addition of alkylene oxide, the internal pressure was maintained for 1 h, and the monomer removal was performed for 0.5 h to obtain a polyether polyol having a number average molecular weight of 11900 g / mol and a viscosity of 2759 mPa·s;

[0066] (3) 1200 g of the polyether polyol prepared in step (2) and 20 g of 3-isopropyl-dimethylbenzyl isocyanate were prepolymerized in the presence of 0.15 g of bismuth neodecanoate. The prepolymerization temperature was 80±10° C. The infrared spectrum recorded the peak at 2261 cm -1 The disappearance of the peak at φ indicates the end point of the reaction, and macromolecular dispersant E is obtained with a viscosity of 3160 mPa·s.

[0067] Comparative Example 2

[0068] The preparation method of the macromolecular dispersant F comprises the following steps:

[0069] (1) The steps are the same as those in Example 1;

[0070] (2) 0.04 g of a modified DMC catalyst was added to 400 g of the low molecular weight polyether 1 obtained in step (1), the temperature was raised to 130° C., dehydrated for 1 h, and then 35 g of propylene oxide was added dropwise to initiate the polymerization reaction. Then, a mixture of 1250 g of propylene oxide and 285 g of ethylene oxide was added to continue the polymerization reaction. The polymerization temperature was 120±20° C. After the alkylene oxide was added, the internal pressure was maintained for 1 h, and the monomer removal was performed for 0.5 h to obtain a polyether polyol having a number average molecular weight of 19100 g / mol and a viscosity of 5100 mPa·s;

[0071] (3) 1910 g of the polyether polyol prepared in step (2) and 15.5 g of 2-ethyl isocyanate were prepolymerized in the presence of 0.1 g of zinc neodecanoate. The prepolymerization temperature was 80 ± 10 °C. The infrared spectrum was recorded at 2261 cm -1 The disappearance of the peak at φ indicates the end point of the reaction, and macromolecular dispersant F is obtained with a viscosity of 5655 mPa·s.

[0072] The macromolecular dispersants A, B, C, D, E and F prepared in Examples 1-4 and Comparative Examples 1-2 were respectively used to prepare polymer polyols. The preparation method thereof comprises the following steps:

[0073] 1) Mix the macromolecular dispersant, isopropanol, styrene (SM) and acrylonitrile (AN) and add them into the batching tank, then add dimethyl azobisisobutyrate, and transport the mixture from the feed tank to the static mixer through a horizontal flow pump, and then enter the two reactors connected in series for polymerization, wherein the mixed reaction temperature of the two reactors is 110±5°C, and the residence time in the two reactors is 60 minutes respectively, and the pre-reactant from the second reactor is cooled by a cooler and collected for use;

[0074] The mass percentages of the raw materials used are as follows:

[0075] Macromolecular dispersant: 24%;

[0076] Ethylenically unsaturated monomer (mixture of styrene and acrylonitrile in a molar ratio of 1:1): 15.8%;

[0077] Isopropyl alcohol: 60%;

[0078] Dimethyl azobisisobutyrate: 0.2%.

[0079] 2) Pre-reactant, basic polyether polyol INOVOL F5631, styrene and acrylonitrile are mixed and added into a batching tank, and then dimethyl azobisisobutyrate is added, and the material is transported from the feed tank to the static mixer through a horizontal flow pump, and then enters the first reactor and the second reactor in sequence through a feed pipe to allow the components to be fully mixed and reacted, wherein the reaction temperature of the two reactors is 130±2°C, and the residence time in the two reactors is 60 minutes respectively, and the crude product from the second reactor is introduced into a stripping reactor, and vacuum is applied to remove unreacted volatiles to obtain a polymer polyol;

[0080] The mass percentages of the raw materials used are as follows:

[0081] Pre-reactant: 12.5%;

[0082] INOVOL F5631: 40%;

[0083] Dimethyl azobisisobutyrate: 0.25%;

[0084] Ethylenically unsaturated monomer (mixture of styrene and acrylonitrile in a molar ratio of 2:1): 47.25%.

[0085] The performance tests were performed on the polymer polyols prepared by using the macromolecular dispersants A, B, C, D, E and F of Examples 1-4 and Comparative Examples 1-2, respectively. The test methods for solid content and viscosity were based on GB / T 31062-2014.

[0086] Time to pass through the sieve (s): Take 200 g of polymer polyol, heat it to 100°C, then sieve it through a 200-mesh sieve, and record the time required for the polymer polyol to completely pass through the sieve under the action of gravity.

[0087] The test results are shown in Table 1.

[0088] Table 1 Performance test results

[0089]

[0090] It can be seen from the test data in Table 1 that, compared with Comparative Examples 1-2, the viscosity of the polymer polyols prepared using the macromolecular dispersants of Examples 1-4 is significantly reduced, the filtration time is significantly shortened, and the dispersion effect and the ability to anchor polymer particles are significantly enhanced.

Claims

1. A method for preparing a dendritic macromolecular dispersant, characterized in that: The following steps are involved: (1) Using sorbitol as the initiator, the alkylene oxide is polymerized in the presence of a catalyst to obtain a low molecular weight polyether; (2) subjecting the low molecular weight polyether obtained in step (1) to an esterification reaction with 2,2-dihydroxymethylpropionic acid in the presence of a catalyst to obtain a polyester ether intermediate; (3) subjecting the polyester ether intermediate obtained in step (2) to a polymerization reaction with alkylene oxide under the action of a catalyst to obtain a dendritic polyether; (4) The dendritic polyether prepared in step (3) is subjected to a prepolymerization reaction with an unsaturated isocyanate in the presence of a catalyst to obtain a dendritic macromolecular dispersant.

2. The method for preparing a dendritic macromolecular dispersant according to claim 1, characterized in that: In the step (1), the catalyst is an alkali metal catalyst; and the number average molecular weight of the low molecular weight polyether is 2490-4050 g / mol.

3. The method for preparing the dendritic macromolecular dispersant according to claim 1, characterized in that: In the step (2), the molar ratio of the low molecular weight polyether to 2,2-dihydroxymethylpropionic acid is 1:(0.9-4); the catalyst is one of concentrated sulfuric acid or p-toluenesulfonic acid; and the temperature of the esterification reaction is 130-160°C.

4. The method for preparing a dendritic macromolecular dispersant according to claim 1, characterized in that: In the step (3), the catalyst is a DMC catalyst; the number average molecular weight of the dendritic polyether is 11800-19450 g / mol.

5. The method for preparing the dendritic macromolecular dispersant according to claim 1, characterized in that: In the steps (1) and (3), the alkylene oxide is one or more of propylene oxide and ethylene oxide; and the polymerization reaction temperature is 100-140°C.

6. The method for preparing a dendritic macromolecular dispersant according to claim 1, characterized in that: In the step (4), the unsaturated isocyanate is one of 3-isopropyl-dimethylbenzyl isocyanate, 2-ethyl methylacrylate isocyanate or ethyl isocyanate acrylate.

7. The method for preparing a dendritic macromolecular dispersant according to claim 1, characterized in that: In the step (4), the molar ratio of the dendritic polyether to the unsaturated isocyanate is 1:(0.8-1.1).

8. The method for preparing a dendritic macromolecular dispersant according to claim 1, characterized in that: In the step (4), the catalyst is a bismuth catalyst or a zinc catalyst; and the temperature of the prepolymerization reaction is 70-90°C.

9. A dendritic macromolecular dispersant, characterized in that: The dendritic macromolecular dispersant is prepared by the preparation method of any one of claims 1 to 8.

10. Use of the dendritic macromolecular dispersant according to claim 9, characterized in that: Used in the preparation of polymer polyols.

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