Polymer polyol and preparation method thereof

Abstract

The invention provides a polymer polyol and a preparation method thereof, and the method comprises the following steps: 1, reacting a raw material mixture in a first reactor at a first temperature to obtain a first reaction material; 2, the first reaction material is subjected to a reaction in a second reactor at a second temperature, and a second reaction material is obtained; 3, the second reaction material is subjected to a reaction in a third reactor at a third temperature, a product mixture is obtained, and the product mixture contains the polymer polyol; the second temperature is equal to or higher than the first temperature; the third temperature is higher than the second temperature. According to the invention, the polymer polyol with required low viscosity, high solid content and stable properties can be prepared.

Description

Technical Field

[0001] This application relates to the fields of chemical engineering and polymer science, and more specifically to a polymeric polyol with improved properties and a method for its preparation. Background Technology

[0002] Polymer polyols (POP), also known as grafted polyether polyols, are produced by grafting vinyl monomers onto flexible foam polyether polyols (referred to as base polyethers) through free radical in-situ polymerization. POP combines the inherent toughness of the polyether backbone with the rigidity of the grafted vinyl polymer side chains. These properties significantly improve the modulus, tensile strength, tear strength, hardness, and flame retardancy of polyurethane foams and elastomers made from POP, and can effectively reduce the material's density. The resulting products exhibit high load-bearing capacity and good resilience, thus finding widespread use in the automotive and furniture industries. Therefore, there is a significant demand in current technology for POP with high solids content, low viscosity, and high stability.

[0003] However, contradictorily, existing POP production processes consistently have flaws, resulting in unsatisfactory POP products. Specifically, existing methods cannot simultaneously achieve high solids content, low viscosity, and high stability; some existing batch processes have low production efficiency, failing to meet the demands of large-scale industrial production; and the direct devolatilization post-treatment in existing methods easily leads to product agglomeration, increased viscosity, and decreased stability. There is an urgent need to develop a new technology that can solve these problems.

[0004] In response to the problems existing in the prior art, the inventors of this application have developed a new POP synthesis method through extensive and in-depth research, which unexpectedly solves a long-standing problem in the prior art. Summary of the Invention

[0005] The first aspect of this application provides a method for preparing polymeric polyols, the method comprising:

[0006] Step 1: React the raw material mixture in the first reactor at the first temperature to obtain the first reactant.

[0007] Step 2: The first reactant is reacted in the second reactor at a second temperature to obtain the second reactant;

[0008] Step 3: The second reactant is reacted in a third reactor at a third temperature to obtain a product mixture containing the polymer polyol;

[0009] The first temperature is 100-140℃, the second temperature is 100-140℃, and the third temperature is 150-180℃;

[0010] Therefore, the second temperature is equal to or higher than the first temperature; the third temperature is higher than the second temperature.

[0011] According to one embodiment of the first aspect of this application, the method further includes a fourth step after step three: purifying the product mixture.

[0012] According to another embodiment of the first aspect of this application, step four includes one or more of the following: flash evaporation, nitrogen stripping, and steam stripping.

[0013] According to another embodiment of the first aspect of this application, the method is performed in a continuous manner.

[0014] According to another embodiment of the first aspect of this application, the reaction pressure in step one is 0.3-3 MPa, the residence time of the raw material mixture in the first reactor is 0.5-2 hours, and the stirring rate is 300-500 rpm.

[0015] According to another embodiment of the first aspect of this application, the reaction pressure in step two is 0.3-3 MPa, the residence time of the first reactant in the second reactor is 0.5-2 hours, and the stirring rate is 300-500 rpm.

[0016] According to another embodiment of the first aspect of this application, the reaction pressure in step three is 0.8-5 MPa, the residence time of the second reactant in the third reactor is 2-4 hours, and the stirring rate is 400-600 rpm.

[0017] According to another embodiment of the first aspect of this application, the raw material mixture comprises: a base polyether, a vinyl monomer, a chain transfer agent, an initiator, and a dispersant.

[0018] According to another embodiment of the first aspect of this application, the base polyether is a polyether polyol with a hydroxyl value of 30-60 and a hydroxyl functionality of 2-6.

[0019] According to another embodiment of the first aspect of this application, the vinyl monomer is selected from one or more of the following: C2-C12 aliphatic olefins, C8-C16 aromatic olefins, halogenated C2-C12 aliphatic olefins, halogenated C8-C16 aromatic olefins, (meth)acrylonitrile, (meth)acrylate and (meth)acrylic acid.

[0020] According to another embodiment of the first aspect of this application, in the raw material mixture, the amount of the vinyl monomer is 25-200 parts by weight, based on 100 parts by weight of the base polyether.

[0021] According to another embodiment of the first aspect of this application, the chain transfer agent is selected from one or more of the following: isopropanol, isobutanol, propylene glycol, ethylene glycol, and dodecyl mercaptan.

[0022] According to another embodiment of the first aspect of this application, in the raw material mixture, the amount of the chain transfer agent is 2-8 parts by weight, based on 100 parts by weight of the vinyl monomer.

[0023] According to another embodiment of the first aspect of this application, the initiator is an azo initiator and / or a peroxide initiator.

[0024] According to another embodiment of the first aspect of this application, the azo initiator is selected from one or more of the following: azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, and azobisisobutyrate.

[0025] According to another embodiment of the first aspect of this application, the peroxide initiator is selected from one or more of the following: lauroyl peroxide, tert-butyl peroxide (2-ethylhexanoate), tert-butyl peroxide diethylacetate, and tert-amyl peroxide (2-ethylhexanoate).

[0026] According to another embodiment of the first aspect of this application, in the raw material mixture, the amount of the initiator is 0.1-3 parts by weight, based on 100 parts by weight of the vinyl monomer.

[0027] According to another embodiment of the first aspect of this application, the dispersant comprises one or more of the following: XDI-modified polyether polyol, hydroxyl acrylate-modified polyether polyol, XDI and hydroxyl acrylate-modified polyether polyol, maleic anhydride-modified polyether polyol, TMI-modified polyether polyol, acrylic acid-modified polyether polyol, and mixtures or copolymers of two or more of the above.

[0028] According to another embodiment of the first aspect of this application, in the raw material mixture, the amount of the dispersant is 0.5-20 parts by weight, based on 100 parts by weight of the vinyl monomer.

[0029] The second aspect of this application provides a polymeric polyol, which is prepared by the method defined in any embodiment of the first aspect of this application.

[0030] According to one embodiment of the second aspect of this application, the polymeric polyol has a viscosity of less than 5000 cp and a solids content of more than 50% by weight.

[0031] In the detailed implementation section below, the method and POP product of this application will be further described with reference to the accompanying drawings. Attached Figure Description

[0032] Figure 1 A process flow diagram according to one embodiment of this application is shown. Detailed Implementation

[0033] The “range” disclosed in this document takes the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this way are inclusive and composable; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if the minimum range values ​​are listed as 1 and 2, and if the maximum range values ​​are listed as 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0034] In this application, unless otherwise stated, the numerical range "ab" is a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this document, and "0-5" is simply a shortened representation of these numerical combinations.

[0035] Unless otherwise specified in this application, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0036] Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0037] In this application, unless otherwise specified, the term "comprising" as used herein can be either open-ended or closed-ended. For example, "comprising" may mean that it may also include other components not listed, or it may only include the listed components.

[0038] The polymeric polyol (POP) synthesized by the method of this invention is prepared by in-situ free radical polymerization of monomers (i.e., "vinyl monomers") with carbon-carbon double bonds, using polyether polyols (also referred to herein as base polyethers, base polyether polyols, or base polyols) as raw materials to form grafts attached to the backbone of the base polyether polyol. The vinyl monomers also act as solvents during the POP synthesis process, and are therefore also referred to as "solvents" or "solvent compounds".

[0039] The method of the present invention includes reacting a mixture of raw materials sequentially in three reactors connected in series, and—optionally—purifying the mixture in a purification apparatus after the reaction to remove volatile components (also known as devolatilization or devolatiles).

[0040] According to one embodiment of this application, the raw material mixture comprises: a base polyether, a vinyl monomer, a chain transfer agent, an initiator, and a dispersant.

[0041] According to one embodiment of this application, the base polyether used is a polyether polyol with a hydroxyl value of 30-60 mg KOH / g, for example, 35-56 mg KOH / g; its hydroxyl functionality can be 2-6, for example, 2-5, 3-5, or 3-4, preferably a polyether polyol with a hydroxyl functionality of 3. According to another embodiment of this application, the number average molecular weight of the base polyether can be 2000-12000, for example, 2500-11000, or 3000-10000, or 3000-9000, or 3000-8000, or 3000-7000, or 3000-6000, or 3000-4000, or within a numerical range obtained by combining any two of the above end values.

[0042] According to another embodiment of this application, the vinyl monomer is selected from one or more of the following: C2-C12 aliphatic olefins, C8-C16 aromatic olefins, halogenated C2-C12 aliphatic olefins, halogenated C8-C16 aromatic olefins, (meth)acrylonitrile, (meth)acrylate, and (meth)acrylic acid; for example, the vinyl monomer is selected from one or more of the following: C2-C6 aliphatic olefins, C8-C12 aromatic olefins, halogenated C2-C6 aliphatic olefins, halogenated C8-C12 aromatic olefins, (meth)acrylonitrile, (meth)acrylate C2-C6 alkyl ester, (meth)acrylate C2-C6 hydroxyalkyl ester, and (meth)acrylic acid. In this invention, halogenation includes fluorination, chlorination, bromination, or iodination, and halogens include fluorine, chlorine, bromine, or iodine. According to a preferred embodiment of this application, the vinyl monomer is selected from one or more of the following: styrene, acrylonitrile, (C2-C6) alkyl methacrylate, C2-C6 alkyl acrylate, and vinyl chloride. According to a further preferred embodiment of this application, the vinyl monomer is a mixture of styrene and acrylonitrile, and the weight ratio of styrene to acrylonitrile in the mixture is 99:1 to 30:70, for example, 90:10 to 50:50, or 80:20 to 60:50, or 70:30 to 65:35.

[0043] According to another embodiment of this application, in the raw material mixture, based on 100 parts by weight of the base polyether polyol, the amount of the vinyl monomer is 25-200 parts by weight, for example, 50-150 parts by weight, or 80-140 parts by weight, or 100-130 parts by weight, or 110-120 parts by weight.

[0044] According to another embodiment of this application, the chain transfer agent comprises one or more of the following: C2-C8 straight-chain or branched aliphatic alkane monools, diols, or triols, and C2-C16 aliphatic alkane thiols. For example, the chain transfer agent may include C3-C8 branched aliphatic alkane monools, C2-C6 straight-chain or branched aliphatic alkane diols, and C6-C12 aliphatic alkane thiols; preferred chain transfer agents include one or more of the following: isopropanol, isobutanol, propylene glycol, ethylene glycol, and dodecanethiol.

[0045] According to another embodiment of this application, in the raw material mixture, the amount of the chain transfer agent is 2-8 parts by weight, for example 3-7 parts by weight, or 5-7 parts by weight, or 6-7 parts by weight, based on 100 parts by weight of the vinyl monomer.

[0046] According to one embodiment of this application, the initiator is an azo initiator, a peroxide initiator, or a mixture of an azo initiator and a peroxide initiator.

[0047] According to an exemplary embodiment of this application, the azo initiator includes azo nitriles and azo carboxylic acid esters, such as azobis(C3-C8)alkylnitriles and azobis(C2-C12)carboxylic acid (C2-C12)alkyl esters; more specific examples are selected from one or more of the following: azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, and azobisisobutyrate.

[0048] According to another exemplary embodiment of this application, the peroxide initiator includes C2-C16 acyl peroxides and peroxidized (C2-C12)carboxylic acid (C2-C12) alkyl esters; for example, C4-C16 acyl peroxides and peroxidized (C4-C12)carboxylic acid (C4-C12) alkyl esters; more specific examples are selected from one or more of the following: lauroyl peroxide, tert-butyl peroxide (2-ethylhexanoate), tert-butyl peroxide diethylacetate, and tert-amyl peroxide (2-ethylhexanoate).

[0049] According to another embodiment of this application, the amount of the initiator is 0.1-3 parts by weight, for example, 0.15-2.5 parts by weight, or 0.2-2 parts by weight, or 0.3-1.2 parts by weight, or 0.4-1 parts by weight, or 0.5-0.8 parts by weight, based on 100 parts by weight of the vinyl monomer.

[0050] According to another embodiment of this application, the dispersant used is obtained by modifying the polyether polyol with a compound containing an active group, thereby attaching the active group to the polyether polyol. For example, the active group may include isocyanate group (NCO), isocyanurate group, carboxylic acid group, carboxylic ester group, carboxylic anhydride group, etc. For example, the compound containing the active group used to modify the polyether polyol may include 3-isopropyl-dimethylbenzyl isocyanate (TMI), isophthalic dimethyl isocyanate (XDI), (meth)acrylate (C1-C12) hydroxyalkyl ester, (meth)acrylate, maleic anhydride, etc.

[0051] The polyether polyol used to synthesize the dispersant has a molecular weight of 3000-18000; a hydroxyl value of 18-56 mgKOH / g; and a hydroxyl functionality of 3-6.

[0052] According to one embodiment of this application, the content of the above-mentioned active groups is 0.5-5% by weight, for example 1-4% by weight, or 2-3% by weight, based on the weight of the dispersant.

[0053] According to one embodiment of this application, the dispersant may include one or more of the following: XDI-modified polyether polyol, hydroxyl acrylate-modified polyether polyol, XDI and hydroxyl acrylate-modified polyether polyol, maleic anhydride-modified polyether polyol, TMI-modified polyether polyol, acrylic acid-modified polyether polyol, and mixtures or copolymers of two or more of the above.

[0054] The dispersants of the present invention can be prepared using techniques known in the art. For example, the XDI-modified polyether polyols, hydroxyl acrylate-modified polyether polyols, and TMI-modified polyether polyols used in the present invention can be prepared according to the process described in US7179882B2, and the maleic anhydride-modified polyether polyols used in the present invention can be prepared according to the process described in "Synthesis and Characterization of Maleic Acid Polyether Ester Macromonomers" (Lv Shijun, Guo Ruiwei, Chemical Industry and Engineering, No. 6, 2003).

[0055] According to another embodiment of this application, the amount of the dispersant is 1-20 parts by weight, for example 1.5-18 parts by weight, or 2-16 parts by weight, based on 100 parts by weight of the vinyl monomer.

[0056] According to another embodiment of this application, before implementing the method of the present invention, a portion or all of the dispersant can be prepolymerized with a portion of the vinyl monomer, initiator, and chain transfer agent described above to generate a prepolymer. The prepolymer is then used as part of the raw material mixture of the present invention to further improve the compatibility of the dispersant with other components and promote the smooth progress of subsequent polymerization reactions. In the case of preparing the prepolymer and using it as part of the raw material mixture, the prepolymer can be directly regarded as a "polymerization-type" dispersant, or it can be regarded as a combination of the components (dispersant, vinyl monomer, initiator, and chain transfer agent) that form the prepolymer.

[0057] According to another embodiment of this application, the amount of the prepolymer is 0.8-19 parts by weight, for example 1-17 parts by weight, or 1.5-15 parts by weight, based on 100 parts by weight of the free vinyl monomer in the raw material mixture.

[0058] The method of the present invention includes the following steps:

[0059] Step 1: React the raw material mixture in the first reactor at the first temperature to obtain the first reactant.

[0060] Step 2: The first reactant is reacted in the second reactor at a second temperature to obtain the second reactant;

[0061] Step 3: The second reactant is reacted in a third reactor at a third temperature to obtain a product mixture containing the polymer polyol; and

[0062] Step 4: Purify the product mixture to remove low-boiling-point volatile compounds (such as unreacted vinyl monomers, residual chain transfer agents, moisture, etc.) to obtain the purified target product POP.

[0063] According to one embodiment of this application, the above-described steps of the present invention can be performed intermittently or continuously. In the continuous embodiment, the reactants are continuously fed into the first reactor and flow downstream through the second and third reactors and the purification unit in step four as the reaction proceeds, thereby significantly improving the production efficiency of POP.

[0064] According to one embodiment of this application, the raw materials in the reaction mixture undergo preliminary free radical polymerization and grafting reactions in the first reactor. According to another embodiment of this application, the first temperature in the first reactor is 100-140°C, for example, 105-130°C, 110-125°C, or 115-120°C.

[0065] According to another embodiment of this application, the (average) residence time of the raw material mixture in the first reactor is maintained at 0.5-2 hours, preferably 0.5-1 hours.

[0066] According to another embodiment of this application, during the reaction process, the first reactor is maintained under an inert atmosphere, such as nitrogen, argon, helium, or a combination thereof.

[0067] According to another embodiment of this application, the pressure in the first reactor is maintained at 0.3-3 MPa, for example 0.5-2 MPa, or 1-1.5 MPa.

[0068] According to another embodiment of this application, the raw material mixture is continuously stirred in the first reactor, and the stirring speed of the stirring device can be, for example, 300-500 rpm. According to a preferred embodiment of this application, the size of the first reactor is 0.5L-1L, and the inner diameter is 4-8cm; when the first reactor overflows, the material in the reactor is 60%-80%; the stirrer is an anchor-type structure, and the diameter of the stirrer blade is 3-6cm.

[0069] According to another embodiment of this application, before starting the first step, an appropriate amount of base polyether is added to the first reactor as a "base layer," and then the raw material mixture is introduced into the first reactor to carry out the method described in this invention. This operation is performed to make the reaction start more smoothly and uniformly; however, the small amount of base polyether added here as a "base layer" is not included in the range of base polyether content in the raw material mixture described above.

[0070] The reaction mixture undergoes a certain degree of reaction as it flows through the first reactor to obtain a first reactant, which flows into the downstream second reactor for further reaction.

[0071] According to another embodiment of this application, the first reactant undergoes further free radical polymerization and grafting reactions in the second reactor, which is also referred to as "maturation" in this invention. According to another embodiment of this application, the second temperature in the second reactor is 100-140°C, for example, 105-135°C, or 110-130°C, or 115-125°C.

[0072] According to another embodiment of this application, the second temperature is equal to or higher than the first temperature. For example, the second temperature may be 1-10°C, 3-8°C, or 5-7°C higher than the first temperature.

[0073] According to another embodiment of this application, the (average) residence time of the first reactant in the second reactor is maintained at 0.5-2 hours, preferably 0.5-1 hours.

[0074] According to another embodiment of this application, during the reaction process, the second reactor is maintained under an inert atmosphere, such as nitrogen, argon, helium, or a combination thereof.

[0075] According to another embodiment of this application, the pressure in the second reactor is maintained at 0.3-3 MPa, for example 0.5-2 MPa, or 1-1.5 MPa.

[0076] According to another embodiment of this application, the first reactant is continuously stirred in the second reactor, and the stirring speed can be, for example, 300-500 rpm. According to one embodiment of this application, the second reactor has a size of 0.5L-1L and an inner diameter of 4-8cm; when the second reactor overflows, the material in the reactor is 60%-80%; the stirrer has an anchor-type structure, and the stirrer blade diameter is 3-6cm.

[0077] According to a preferred embodiment of this application, the first reactor and the second reactor may have the same or substantially the same size and structure.

[0078] The first reactant undergoes further reaction (maturation) as it flows through the second reactor to obtain the second reactant, which flows into the downstream third reactor for further reaction.

[0079] According to another embodiment of this application, the second reactant undergoes sufficient free radical polymerization and grafting reactions in the third reactor, which is also referred to as "heated polymerization" in this invention. According to another embodiment of this application, the third temperature in the third reactor is 150-180°C, for example, 150-170°C, or 150-160°C.

[0080] According to another embodiment of this application, the third temperature is higher than the second temperature. For example, the third temperature may be 10-50°C, 20-40°C, or 25-30°C higher than the second temperature.

[0081] According to another embodiment of this application, the (average) residence time of the second reactant in the third reactor is maintained at 2-4 hours, preferably 2.5-3 hours.

[0082] According to another embodiment of this application, during the reaction process, the third reactor is maintained under an inert atmosphere, such as nitrogen, argon, helium, or a combination thereof.

[0083] According to another embodiment of this application, the pressure in the third reactor is maintained at 0.3-3 MPa, for example 0.5-2 MPa, or 1-1.5 MPa.

[0084] According to another embodiment of this application, the second reactant is continuously stirred in the third reactor, and the stirring speed can be, for example, 400-600 rpm. According to a preferred embodiment of this application, the third reactor has a size of 2L-5L and an inner diameter of 8-20cm; the stirrer is an anchor-type structure with a blade diameter of 12-30cm. According to another embodiment of this application, the structural design of the third reactor is the same as that of the first and second reactors. According to another embodiment of this application, the volume of the third reactor is larger than the volumes of the first and second reactors, for example, the volume of the third reactor is 2-10 times that of the first reactor.

[0085] According to another embodiment of this application, the stirring intensity in the third reactor is higher than that in the first and second reactors. For example, the stirring intensity in the third reactor is 10-100% higher than that in the first and second reactors, such as 20-80% or 25-50%.

[0086] The second reactant undergoes a full and complete reaction as it flows through the third reactor to obtain a product mixture, which can then flow into a downstream purification unit for purification.

[0087] According to one embodiment of this application, the purification includes one or more of the following: flash evaporation, nitrogen stripping, and steam stripping; preferably, the volatile matter is removed by flash evaporation.

[0088] According to another embodiment of this application, the purification operation is carried out in a flash evaporator (e.g., a flash tank) at a low pressure. The flash evaporation operation is carried out at a pressure of 1 kPa to 70 kPa, preferably 10 kPa to 50 kPa, and the flash evaporation temperature is 80 to 200°C, preferably 100 to 150°C.

[0089] According to an exemplary embodiment of this application, the method of the present invention is implemented in the following manner:

[0090] Step 1: Weigh an appropriate amount of base polyether and add it to the first reactor. Place it at the bottom of the reactor and introduce nitrogen into the first reactor through the air inlet pipe. Use nitrogen to replace and remove the air in the first reactor. After the reactor temperature rises to the rated temperature, deliver the prepared raw material mixture into the first reactor at the rated flow rate. Start stirring to ensure sufficient reaction time and adjust the pressure of the first reactor.

[0091] Step 2: Introduce nitrogen into the second reactor through the air inlet pipe. The nitrogen will replace and remove the air in the second reactor, raising the reactor temperature to the rated temperature. After the first reactor is full, the nitrogen will overflow into the second reactor to continue the maturation reaction. Start stirring to ensure sufficient reaction time and adjust the pressure of the second reactor.

[0092] Step 3: Introduce nitrogen into the third reactor through the air inlet pipe. The nitrogen will replace and remove the air in the third reactor, raising the reactor temperature to the rated temperature. After the second reactor is full, overflow into the third reactor. Start stirring and continue high-temperature treatment of the product to ensure sufficient residence time. Adjust the pressure of the third reactor.

[0093] Step 4: After the third reaction vessel is full, the overflow is transferred to the flash devolatilization device to recover isopropanol, remove residual water and unreacted monomers, and obtain the finished polymer polyol.

[0094] The advantages of this invention are:

[0095] 1. This invention enables the synthesis of POP to be carried out in three reactors. During the passage of material through the first and second reactors, nucleation and particle growth occur simultaneously. As new nuclei are generated, existing particles and newly generated particles compete for growth. In addition, the different particle residence times caused by backmixing result in different particle growth lifetimes, leading to a relatively wide distribution of dispersed particle size in the polymer polyol. When the product continues to pass through the third reactor, the high-temperature residence process shears and reorganizes the agglomerated large particles. Without sacrificing high solids content, the viscosity of the polymer polyol is further reduced, forming smaller and more stable particles. This results in smaller, more uniform, and more stable POP particles, and the obtained POP has the advantages of low viscosity, high solids content, and stable product properties.

[0096] 2. The method of the present invention can also improve the conversion rate of monomers by setting different reaction conditions in three reactors, especially by reducing the residual amount of vinyl monomers such as styrene in the product mixture and reducing the pressure of subsequent devolatilization processes.

[0097] 3. The method of the present invention achieves further improvement in the viscosity, solid content and stability of the product POP through further selection of process conditions.

[0098] The methods of this application are specifically illustrated in the following embodiments, the purpose of which is to provide a better understanding of the content of this application. It should be understood that these embodiments are merely illustrative and not restrictive. The reagents used in the embodiments are all commercially available and used directly without further purification.

[0099] Example

[0100] In the following examples, the "polyether polyol modified with isocyanate (XDI) and hydroxyl acrylate groups" used was synthesized according to the process described in patent US 7179882 B2. The base polyether used in the following examples was a commercial product, DEP-5631D, purchased from Shandong Lanxing Dongda Co., Ltd., with a hydroxyl value of 56, a hydroxyl functionality of 3, and a number-average molecular weight of 3000; the F3 dispersant used in Example 2 was synthesized according to the steps described in "Synthesis and Characterization of Maleic Acid Polyether Ester Macromonomers" (Lv Shijun, Guo Ruiwei, Chemical Industry and Engineering, No. 6, 2003). The samples were centrifuged using a Titan HDC-15K benchtop high-speed centrifuge and then dried using a Thermo Fisher Vacutherm vacuum oven, and the solid content was measured; the particle size distribution was characterized using a Malvern Mastersizre 3000 laser particle size analyzer; and the viscosity was measured using a Brookfield DV2T viscometer.

[0101] Example 1

[0102] In this embodiment, the prepolymer was first prepared according to the following steps: 108g of polyether polyol modified with isophthalic acid (XDI) and hydroxyl acrylate groups and 92g of isopropanol were added to a 1L reactor, and then the reactor was heated to 115°C. 25g of acrylonitrile, 25g of styrene, 0.2g of tert-amyl peroxide-2-ethylhexanoate and 200g of isopropanol were mixed together and added to the reactor at a constant rate over 1 hour using a horizontal flow pump, while continuously stirring in the reactor during the addition process. After the addition was complete, the reactor was kept at 115°C for 0.5 hours to obtain the prepolymer. The solid content of the prepolymer was measured to be 2.1% by weight, and the volume average particle size D[4,3] was 0.75μm.

[0103] Next, the prepolymer is used as a polymeric dispersant in... Figure 1 The method of the present invention is carried out in the reaction apparatus shown. The reaction apparatus includes three reaction vessels connected in sequence, wherein the first and second reaction vessels have a volume of 0.5 L and the third reaction vessel has a volume of 3 L.

[0104] Table 1: Raw material mixture used to prepare POP in Example 1

[0105] raw material Quality percentage styrene 32 Acrylonitrile 16 Isopropanol 3.2 prepolymer 6.2 tert-amyl peroxy-2-ethylhexanoate 0.25 Basic polyether 42.35

[0106] First, prepare the raw material mixture as shown in Table 1, and then proceed with the following steps:

[0107] Step 1: Weigh 200g of the base polyether and add it to the first reactor as a base. Introduce nitrogen gas into the first reactor through the air inlet pipe to displace and remove air from the reactor. Turn on the heating device to raise the reactor temperature to 120℃. Pour the prepared raw material mixture into the first reactor at a flow rate of 15mL / min. The residence time of the material in the first reactor is 0.5h. Continuously stir the mixture in the first reactor at a speed of 300rpm, maintaining the pressure inside the reactor at 1.5MPa.

[0108] Step Two: Nitrogen gas is introduced into the second reactor through the air inlet pipe to displace and remove air from the second reactor. The heating device is then turned on, raising the reactor temperature to 125°C. After the material in the first reactor is full, it continuously overflows into the second reactor to continue the ripening reaction. The residence time of the material in the second reactor is 0.5 hours. The second reactor is continuously stirred at a speed of 300 rpm, and the pressure inside the reactor is maintained at 1.5 MPa.

[0109] Step 3: Nitrogen gas is introduced into the third reactor through the air inlet pipe to displace and remove the air from the third reactor. The heating device is then turned on, raising the reactor temperature to 150°C. After the material in the second reactor is full, it continuously overflows into the third reactor to continue the high-temperature polymerization reaction. The residence time of the material in the third reactor is 3 hours. The third reactor is continuously stirred at a speed of 500 rpm, and the pressure inside the reactor is maintained at 1.5 MPa.

[0110] After the reaction continued for 6 hours, samples were taken from the outputs of the second and third reactors, and the volatiles were removed in a flash evaporator at 150°C and 2 kPa. The particle size distribution, viscosity, and solid content were measured. The results are summarized in Table 2 below.

[0111] Table 2: Particle size distribution, viscosity, and solid content of POP before and after treatment in the third reactor.

[0112]

[0113] Example 2

[0114] Example 2 uses the same reaction equipment as Example 1.

[0115] In this embodiment, 1386g of vinyl monomer (924g of styrene and 462g of acrylonitrile), 217g of chain transfer agent (isopropanol), 77.2g of dispersant (F3), 11.8g of initiator (AIBN), and 1234g of base polyether (5631) were first mixed to obtain a raw material mixture.

[0116] Step 1: Weigh 200g of polyether (as the base polyether) and add it to the first reactor as a base. Introduce nitrogen into the first reactor through the air inlet pipe to displace and remove air from the reactor. Turn on the heating device to raise the reactor temperature to 120℃. Feed the prepared raw material mixture into the first reactor at a flow rate of 15mL / min. The residence time of the material in the first reactor is 0.5h. Continuously stir the mixture in the first reactor at a speed of 200rpm, maintaining the pressure inside the reactor at 1.0MPa.

[0117] Step Two: Nitrogen gas is introduced into the second reactor through the air inlet pipe to displace and remove the air from the second reactor. The heating device is then turned on, raising the reactor temperature to 125°C. After the material in the first reactor is full, it continuously overflows into the second reactor to continue the ripening reaction. The residence time of the material in the second reactor is 0.5 hours. The second reactor is continuously stirred at a speed of 200 rpm, and the pressure inside the reactor is maintained at 1.0 MPa.

[0118] Step 3: Nitrogen gas is introduced into the third reactor through the air inlet pipe to displace and remove the air from the third reactor. The heating device is then turned on, raising the reactor temperature to 150°C. After the material in the second reactor is full, it continuously overflows into the third reactor to continue the high-temperature polymerization reaction. The residence time of the material in the third reactor is 2 hours. The third reactor is continuously stirred at a speed of 400 rpm, and the pressure inside the reactor is maintained at 1.0 MPa.

[0119] Step 4: After the third reactor is filled, the overflow material is transported to the flash tank, where it is subjected to devolatiles at 150°C and 2 kPa pressure to obtain the target product POP.

[0120] Samples were taken from the outputs of the second and third reactors and subjected to volatilization in a flash evaporator. The particle size distribution, viscosity, and solid content were then analyzed. The results are summarized in Table 3 below.

[0121] Table 3. Particle size distribution, viscosity, and solid content of POP before and after treatment in the third reactor.

[0122]

[0123] Example 3

[0124] In this embodiment, the prepolymer was first prepared according to the following steps: 108g of maleic anhydride-modified polyether polyol and 92g of isopropanol were added to a 1L reactor, and then the reactor was heated to 115°C. 25g of acrylonitrile, 25g of styrene, 0.2g of tert-amyl peroxide-2-ethylhexanoate, and 200g of isopropanol were mixed together and added to the reactor at a uniform rate over 1 hour using a horizontal flow pump, with continuous stirring during the addition process. After the addition was complete, the reactor was kept at 115°C for 0.5 hours to obtain the prepolymer. The solid content of the prepolymer was measured to be 2.3% by weight, and the volume average particle size D[4,3] was 0.75μm.

[0125] Next, the prepolymer is used as a polymeric dispersant in... Figure 1 The method of the present invention is carried out in the reaction apparatus shown. The reaction apparatus includes three reaction vessels connected in sequence, wherein the first and second reaction vessels have a volume of 0.5 L and the third reaction vessel has a volume of 3 L.

[0126] The raw materials shown in Table 4 are mixed together to obtain a raw material mixture for preparing POP.

[0127] Table 4: Raw material ratios for POP preparation in Example 4

[0128] raw material Quality percentage styrene 32 Acrylonitrile 16 Dispersant (maleic anhydride-modified polyether polyol) 1 Isopropanol 3.2 prepolymer 6.2 tert-amyl peroxy-2-ethylhexanoate 0.25 Basic polyether 41.35

[0129] POP preparation:

[0130] Next, the POP synthesis steps and conditions of Example 1 were repeated three times using the raw material mixture described above. The only difference was that the temperature of the third reactor was set to 150°C in the first experiment, 180°C in the second experiment, and 125°C in the third experiment. All other steps and conditions were the same as in Example 1. The solid content, viscosity, and monomer conversion rate of the POP product after treatment at different temperatures are shown in Table 5.

[0131] In addition, the products synthesized in these three experiments were placed in separate glass bottles, sealed, and left to stand for 6 months under normal temperature and differential pressure conditions. The results were then observed to see if the materials in the bottles aggregated or precipitated. The results are summarized in Table 5.

[0132] Table 5. Solid content, viscosity, and monomer conversion rate of POP after treatment at different temperatures.

[0133]

Claims

1. A method for preparing polymeric polyols, the method comprising: Step 1: React the raw material mixture in the first reactor at the first temperature to obtain the first reactant. Step 2: The first reactant is reacted in the second reactor at a second temperature to obtain the second reactant; Step 3: The second reactant is reacted in a third reactor at a third temperature to obtain a product mixture containing the polymer polyol; The first temperature is 100-140℃, the second temperature is 100-140℃, and the third temperature is 150-180℃; The second temperature is equal to or higher than the first temperature; the third temperature is higher than the second temperature.

2. The method according to claim 1, characterized in that, The method further includes a fourth step after step three: purifying the product mixture; Step four includes one or more of the following: flash evaporation, nitrogen stripping, and steam stripping.

3. The method according to claim 1, characterized in that, The method is performed continuously.

4. The method according to any one of claims 1-3, characterized in that, The reaction pressure in step one is 0.3-3 MPa, the residence time of the raw material mixture in the first reactor is 0.5-2 hours, and the stirring rate is 300-500 rpm; The reaction pressure in step two is 0.3-3 MPa, the residence time of the first reactant in the second reactor is 0.5-2 hours, and the stirring rate is 300-500 rpm. The reaction pressure in step three is 0.8-5 MPa, the residence time of the second reactant in the third reactor is 2-4 hours, and the stirring rate is 400-600 rpm.

5. The method according to any one of claims 1-3, characterized in that, The raw material mixture comprises: a base polyether, a vinyl monomer, a chain transfer agent, an initiator, and a dispersant.

6. The method according to claim 5, characterized in that, The base polyether is a polyether polyol with a hydroxyl value of 30-60 and a hydroxyl functionality of 2-6; The vinyl monomer is selected from one or more of the following: C2-C12 aliphatic olefins, C8-C16 aromatic olefins, halogenated C2-C12 aliphatic olefins, halogenated C8-C16 aromatic olefins, (meth)acrylonitrile, (meth)acrylate and (meth)acrylic acid. In the raw material mixture, the amount of the vinyl monomer is 25-200 parts by weight, based on 100 parts by weight of the base polyether.

7. The method according to claim 5, characterized in that, The chain transfer agent is selected from one or more of the following: isopropanol, isobutanol, propylene glycol, ethylene glycol, and dodecyl mercaptan; In the raw material mixture, the amount of the chain transfer agent is 2-8 parts by weight, based on 100 parts by weight of the vinyl monomer; The initiator is an azo initiator and / or a peroxide initiator; The azo initiator is selected from one or more of the following: azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, and azobisisobutyrate; The peroxide initiator is selected from one or more of the following: lauroyl peroxide, tert-butyl peroxide (2-ethylhexanoate), tert-butyl diethylacetate peroxide, and tert-amyl peroxide (2-ethylhexanoate). In the raw material mixture, the amount of the initiator is 0.1-3 parts by weight, based on 100 parts by weight of the vinyl monomer.

8. The method according to claim 5, characterized in that, The dispersant comprises one or more of the following: XDI-modified polyether polyol, hydroxyl acrylate-modified polyether polyol, XDI and hydroxyl acrylate-modified polyether polyol, maleic anhydride-modified polyether polyol, TMI-modified polyether polyol, acrylic acid-modified polyether polyol, and mixtures or copolymers of two or more of the above. The amount of the dispersant is 0.5-20 parts by weight, based on 100 parts by weight of the vinyl monomer.

9. A polymeric polyol, which is prepared by the method of any one of claims 1-8.

10. The polymer polyol according to claim 9, characterized in that, The polymer polyol has a viscosity of less than 5000 cp and a solids content of more than 50% by weight.

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