High bio-based, low viscosity oligomeric polyols and their preparation methods

Abstract

This invention discloses a high-bio-based, low-viscosity oligomeric polyol and its preparation method, relating to the field of oligomeric polyol technology. The technical solution involves preparing the following raw materials via transesterification: 40-60 parts by weight of bio-based polyester polyol, 20-30 parts by weight of bio-based polyether polyol, 20-30 parts by weight of vegetable oil, 3-5 parts by weight of amine polyether polyol, a catalyst, and a composite antioxidant; wherein the amine polyether polyol is a polyether polyol prepared by initiating propylene oxide with an amine compound as an initiator. The oligomeric polyol prepared by this invention possesses the dual advantages of high bio-based content and low viscosity, and its structure contains both ester and ether bonds, making it widely applicable as a substitute for traditional petroleum-based polyester polyols and polyether polyols in the preparation of various polyurethane products, thereby improving the sustainability and environmental friendliness of materials.

Description

Technical Field

[0001] This invention relates to the field of oligomeric polyol technology, specifically to oligomeric polyols with high bio-based content and low viscosity, and their preparation methods. Background Technology

[0002] Polyurethane materials, due to their excellent mechanical properties, wear resistance, adhesion, and controllability, are widely used in industrial fields such as adhesives, coatings, elastomers, and foamed plastics. They are typically composed of three parts: isocyanate, oligomeric polyol, and chain extender. Currently, the raw materials for polyurethane mainly rely on petrochemical resources. However, its production process not only consumes a large amount of non-renewable petroleum resources but also results in high carbon emissions and environmental pollution, making it difficult to meet increasingly stringent environmental policies and sustainable development requirements worldwide. Guided by environmental policies, the research and application of bio-based chemicals has become a key direction in the field of new materials.

[0003] Traditional polyurethane oligomer polyols mainly include polyester polyols and polyether polyols, typically accounting for over 50%. The key to developing bio-based polyurethane products lies in developing bio-based oligomer polyols. Currently, various bio-based oligomer polyols have gradually gained market application and have been widely reported. While this has alleviated dependence on petroleum resources to some extent, significant technological bottlenecks remain: on the one hand, most bio-based products have low bio-based content (often below 50%), failing to truly achieve large-scale substitution of petroleum resources; on the other hand, current bio-based oligomer polyols are usually single bio-based polyester polyols or bio-based polyether polyols. Bio-based polyester polyols typically have high viscosity due to the presence of high cohesive ester bonds, limiting their applications. Therefore, there is an urgent need to develop a bio-based oligomer polyol with high bio-based content and low viscosity to quickly and effectively replace traditional petroleum-based oligomer polyols, enabling the preparation of bio-based polyurethane materials, meeting sustainable development requirements, and giving the corresponding products a broad market and added value. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a low-viscosity oligomeric polyol with high bio-based content and its preparation method. This invention can solve the problem of non-renewable raw materials for traditional oligomeric polyols, and also solve the problems of low bio-based content and high viscosity of existing oligomeric polyols.

[0005] The technical solution of this invention is as follows:

[0006] On the one hand, the present invention provides a low-viscosity oligomeric polyol with high bio-based content, which is prepared by transesterification reaction from the following raw materials in parts by weight: 40-60 parts of bio-based polyester polyol, 20-30 parts of bio-based polyether polyol, 20-30 parts of vegetable oil, 3-5 parts of amine polyether polyol, catalyst, and composite antioxidant; wherein, the amine polyether polyol is a polyether polyol prepared by initiating propylene oxide with amine compounds as initiators.

[0007] Preferably, the bio-based polyester polyol is a polyester polyol synthesized from bio-based raw materials, with a number average molecular weight <1000g / mol and an acid value <2mgKOH / g.

[0008] Preferably, the bio-based polyester polyol is a polylactic acid polyol or a bio-based polyester polyol prepared by an alkyd condensation reaction of a bio-based small molecule polyol and a bio-based small molecule polyacid.

[0009] Preferably, the bio-based small molecule polyol is two of bio-based ethylene glycol, propylene glycol, and glycerol; the bio-based small molecule polyacid is one or two of succinic acid, sebacic acid, and itaconic acid.

[0010] Preferably, the bio-based polyether polyol is a polytrimethylene ether diol polyether polyol with a number average molecular weight of <1000 g / mol synthesized from bio-based raw materials.

[0011] Preferably, the vegetable oil is castor oil, soybean oil, or palm oil.

[0012] Preferably, the hydroxyl value of the amine polyether polyol is 350-500 mg KOH / g.

[0013] Preferably, the catalyst is an organotitanium catalyst or an organobismuth catalyst, and its addition amount is 30-50 ppm of the total material; the composite antioxidant is composed of hindered phenolic antioxidant and phosphite antioxidant, and its addition amount is 1-3‰ of the total material.

[0014] Preferably, the bio-based content of the high bio-based content low viscosity oligomeric polyol is above 95%, the viscosity at 25°C is <8000mPa·s, the acid value is <1mgKOH / g, and the number average molecular weight is 610-982g / mol.

[0015] On the other hand, the present invention provides a method for preparing the above-mentioned high bio-based content, low viscosity oligomeric polyol, comprising the following steps:

[0016] S1: Add bio-based polyester polyol, bio-based polyether polyol, catalyst and composite antioxidant into the reactor, stir at 200-300 rpm under nitrogen protection, and heat to 220-230℃ at a rate of 5-10℃ / min, and keep at the temperature for 1-2 hours.

[0017] S2: Cool down to 160-180℃, add vegetable oil to the reactor, stir at the same speed, raise the temperature to 220-230℃ again, keep the temperature and draw a vacuum, and continue stirring until the system is transparent.

[0018] S3: Cool down to 180-200℃, add amine polyether polyol to the reactor, keep warm for 2-4 hours, take a sample to test the acid value <1mgKOH / g and the viscosity at 25℃ <8000mPa·s, cool down to 80-100℃, release the material, and you will get a low-viscosity oligomer polyol with high bio-based content.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. High bio-based content: The oligomeric polyols prepared by this invention have a bio-based content of more than 95%, and most of the raw materials are made from renewable raw materials, which meets the requirements of sustainable development.

[0021] 2. Low viscosity, facilitating production and processing: This invention employs a composite system of "bio-based polyester polyol + bio-based polyether polyol + vegetable oil + amine polyether polyol," reducing the system viscosity through the synergistic effect of different molecular chain structures. The autocatalytic effect of the amine groups in the amine polyether polyol can regulate the reactivity, shortening the curing time of the prepared oligomeric polyol and isocyanate in the preparation of polyurethane products. Ultimately, the viscosity of the prepared oligomeric polyol at 25℃ is <8000 mPa·s, solving the problems of high viscosity and difficult processing of traditional oligomeric polyols.

[0022] 3. Stepwise Process: A single-stage feeding process may lead to rapid molecular weight growth in the initial reaction phase, forming high-molecular-weight polymers with significantly increased viscosity. Furthermore, simultaneous reactions of all components at high temperatures may trigger thermal decomposition of bio-based polyester polyols or oxidation of vegetable oils, generating additional acidic substances. This invention utilizes a stepwise heating and vacuum process to achieve stepwise transesterification, forming a block structure that ensures uniform chain segment connection, prevents disordered molecular chain growth, and guarantees an acid value of <1 mg KOH / g and a viscosity of <8000 mPa·s at 25°C. This process requires no equipment modification; existing equipment can meet production requirements, enabling low-cost industrialization.

[0023] 4. This invention, through dual-dimensional innovation of "molecular structure design + process control", forms a technical barrier in terms of low viscosity, high bio-based content and application performance, fills the gap of insufficient downstream processability of existing oligomeric polyols, and provides a solution that can replace petroleum-based materials for environmentally friendly polymer materials. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0025] The raw materials used in the examples are from the following sources:

[0026] Bio-based polyester polyol PES-110 is prepared by the alkyd condensation reaction of bio-based ethylene glycol, glycerol and succinic acid. It has an acid value of 1.5 mg KOH / g, a viscosity of 14000 mPa·s at 25℃, a number-average molecular weight of 680 g / mol, and a bio-based content of 100%. It is produced by Shandong Yinuowei Polyurethane Co., Ltd.

[0027] Bio-based polyester polyol PES-9051 is prepared by alkyd condensation reaction of bio-based propylene glycol, glycerol, sebacic acid and itaconic acid. It has an acid value of 1.7 mg KOH / g, a viscosity of 18000 mPa·s at 25℃, a number average molecular weight of 920 g / mol, and a bio-based content of 100%. It is produced by Shandong Yinuowei Polyurethane Co., Ltd.

[0028] Polylactic acid polyol HPBE1000, acid value 1.8mgKOH / g, viscosity at 25℃ 20000mPa·s, number average molecular weight 960g / mol, 100% bio-based content, Anhui Fengyuan Biotechnology Co., Ltd.

[0029] Polytrimethylene ether diol PO3G H1000, viscosity at 25℃ 600mPa·s, number-average molecular weight 980g / mol, 100% bio-based content, SK Chemicals;

[0030] Castor oil, palm oil, soybean oil; Shanghai Kaiyin Chemical Co., Ltd.

[0031] INOVOL R405, a amine polyether polyol, has a viscosity of 4500 mPa·s at 25℃ and a hydroxyl value of 450 mgKOH / g. It is manufactured by Shandong Yinuowei New Materials Co., Ltd.

[0032] Hindered phenolic antioxidants 1010, 1076, 1098, and 1019; phosphite antioxidants 168 and 626; Tianjin Lianlong New Materials Co., Ltd.

[0033] Example 1

[0034] The preparation method of the high bio-based content, low viscosity oligomeric polyol in this embodiment includes the following steps:

[0035] S1: Add 600g of bio-based polyester polyol PES-9051, 200g of polytrimethylene ether diol PO3G H1000, 30ppm of tetrabutyl titanate, 1‰ of hindered phenolic antioxidant 1010 and 1‰ of phosphite antioxidant 168 to the reactor, stir at 300rpm under nitrogen protection, heat to 230℃ at a rate of 10℃ / min, and keep at this temperature for 2h.

[0036] S2: Cool down to 180℃, add 200g of castor oil to the reactor, stir at the same speed, raise the temperature to 230℃ again, keep it at the temperature and evacuate to a vacuum degree of -0.095MPa, continue stirring for 60min until the system is transparent (transmittance ≥90% at 450nm wavelength).

[0037] S3: Cool down to 200℃, add 50g of amine polyether polyol INOVOL R405 to the reactor, keep it at room temperature for 4 hours, take a sample and measure the acid value <1mgKOH / g and the viscosity at 25℃ <8000mPa·s; cool down to 100℃, release the material, and you will get a low-viscosity oligomer polyol with high bio-based content.

[0038] Example 2

[0039] The preparation method of the high bio-based content, low viscosity oligomeric polyol in this embodiment includes the following steps:

[0040] S1: Add 450g of polylactic acid polyol HPBE1000, 300g of polytrimethylene ether diol PO3G H1000, 50ppm of bismuth neodecanoate, 1‰ of hindered phenolic antioxidant 1076 and 1‰ of phosphite antioxidant 626 to the reactor, stir at 200rpm under nitrogen protection, heat to 230℃ at a rate of 10℃ / min, and keep at this temperature for 1h.

[0041] S2: Cool down to 160℃, add 250g of soybean oil to the reactor, stir at the same speed, raise the temperature to 230℃ again, keep it at the temperature and evacuate to a vacuum degree of -0.095MPa, continue stirring for 60min until the system is transparent (transmittance ≥90% at 450nm wavelength).

[0042] S3: Cool down to 180℃, add 40g of amine polyether polyol INOVOL R405 to the reactor, keep it at room temperature for 4 hours, take a sample and measure the acid value <1mgKOH / g and the viscosity at 25℃ <8000mPa·s; cool down to 80℃, release the material, and you will get a low-viscosity oligomer polyol with high bio-based content.

[0043] Example 3

[0044] The preparation method of the high bio-based content, low viscosity oligomeric polyol in this embodiment includes the following steps:

[0045] S1: Add 550g of bio-based polyester polyol PES-110, 200g of polytrimethylene ether diol PO3G H1000, 40ppm of tetrabutyl titanate, 1.5‰ of hindered phenolic antioxidant 1098 and 1.5‰ of phosphite antioxidant 168 to the reactor, stir at 300rpm under nitrogen protection, heat to 220℃ at a rate of 5℃ / min, and keep at this temperature for 2h.

[0046] S2: Cool down to 170℃, add 250g of palm oil to the reactor, stir at the same speed, raise the temperature to 220℃ again, keep it at the temperature and evacuate to a vacuum degree of -0.095MPa, continue stirring for 60min until the system is transparent (transmittance ≥90% at 450nm wavelength).

[0047] S3: Cool down to 180℃, add 30g of amine polyether polyol INOVOL R405 to the reactor, keep it at room temperature for 2 hours, take a sample and measure the acid value <1mgKOH / g and the viscosity at 25℃ <8000mPa·s; cool down to 80℃, release the material, and you will get a low-viscosity oligomer polyol with high bio-based content.

[0048] Example 4

[0049] The preparation method of the high bio-based content, low viscosity oligomeric polyol in this embodiment includes the following steps:

[0050] S1: Add 400g of bio-based polyester polyol PES-9051, 250g of polytrimethylene ether diol PO3G H1000, 50ppm of bismuth neodecanoate, 0.5‰ of hindered phenolic antioxidant 1019, and 0.5‰ of phosphite antioxidant 168 to the reactor. Stir at 250rpm under nitrogen protection, heat to 225℃ at a rate of 8℃ / min, and hold at that temperature for 1.5h.

[0051] S2: Cool down to 180℃, add 300g of castor oil to the reactor, stir at the same speed, raise the temperature to 225℃ again, keep it at the temperature and evacuate to a vacuum degree of -0.095MPa, continue stirring for 60min until the system is transparent (transmittance ≥90% at 450nm wavelength).

[0052] S3: Cool down to 190℃, add 50g of amine polyether polyol INOVOL R405 to the reactor, keep it at room temperature for 3h, take a sample and measure the acid value <1mgKOH / g and the viscosity at 25℃ <8000mPa·s; cool down to 90℃, release the material, and you will get a low-viscosity oligomer polyol with high bio-based content.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that in Comparative Example 1, all raw materials were added to the reactor at once and reacted directly at 220°C when preparing oligomeric polyols.

[0055] Comparative Example 2

[0056] The difference from Example 1 is that in step S3, the amine polyether polyol INOVOL R405 is not added.

[0057] Comparative Example 3

[0058] The difference from Example 1 is that in step S1, polytrimethylene ether diol PO3G H1000 is not added; and in step S2, castor oil is not added.

[0059] Comparative Example 4

[0060] The difference from Example 1 is that step S2 is not performed.

[0061] The acid value (test method refers to GB / T 1668-2008 "Determination of Acid Value and Acidity of Plasticizers"), viscosity (test method refers to GB / T 2794-2013 "Determination of Viscosity of Adhesives - Single Cylinder Rotation Viscometer Method"), number-average molecular weight (test method uses gel permeation chromatography), and bio-based content (test method refers to GB / T39715.3-2021 "Bio-based Content of Plastics - Part 3: Determination of Bio-based Synthetic Polymer Content") of the oligomeric polyols prepared in Examples 1-4 and Comparative Examples 1-4 are shown in Table 1. In addition, polyurethane samples were prepared by directly mixing them with diphenylmethane diisocyanate (MDI) at a mass ratio of 1:1.2, and the curing time was tested (test method refers to GB / T 7124-2021 "Determination of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)"). The test results are shown in Table 2.

[0062] Table 1. Test results of acid value, viscosity, number-average molecular weight and bio-based content of oligomeric polyols prepared in Examples 1-4 and Comparative Examples 1-4.

[0063]

[0064] Table 2. Curing times of polyurethane samples prepared from oligomeric polyols and MDI in Examples 1-4 and Comparative Examples 1-4.

[0065]

[0066] Combining the data in Tables 1 and 2, it can be seen that the oligomeric polyols prepared in Comparative Examples 1-4 are significantly inferior to those in Example 1 in terms of performance. This is because Comparative Example 1 uses a one-step method of "adding all raw materials at once and directly heating the reaction," instead of the key process of "stepwise heating + vacuuming" in Example 1, leading to two major problems:

[0067] (1) Issues with reaction uniformity and residual impurities: Transesterification requires the removal of small molecule byproducts (such as water and low-boiling substances) in stages. In the one-step method, the raw materials such as vegetable oil and amino polyether polyol are mixed too early, and their reactivity is not matched with that of bio-based polyester polyol and bio-based polyether polyol. Some raw materials fail to participate fully in transesterification, and the byproducts cannot be effectively removed by step-by-step vacuuming, which ultimately leads to an increase in acid value (residual trace amounts of unreacted carboxylic acid) and an abnormal increase in number-average molecular weight (local overpolymerization).

[0068] (2) Increased system viscosity and delayed curing: The increase in number-average molecular weight directly leads to a surge in viscosity; at the same time, the small molecule impurities remaining in the system will hinder the cross-linking reaction between oligomeric polyols and MDI, extending the curing time from 20h to 32h, and significantly reducing the reaction efficiency.

[0069] Comparative Example 2 suffered from the failure of two core functions due to the absence of the crucial amino polyether polyol in the raw material formulation:

[0070] (1) Insufficient active sites hinder curing reaction: Amine polyether polyols use amine compounds as initiators, and the amino groups (-NH-) in the molecular chain can serve as active sites, significantly promoting the cross-linking reaction between oligomeric polyols and isocyanate groups (-NCO) in MDI. After the absence of these sites, the system relies solely on hydroxyl groups (-OH) to react with -NCO, resulting in a significant decrease in reaction activity. The curing time doubles from 20h to 40h, which is completely unable to meet the efficiency requirements of practical applications.

[0071] (2) Imbalance between viscosity and acid value control: The hydroxyl value and molecular structure of amine polyether polyols can adjust the degree of polymerization of the system and avoid local over-reaction. After the absence of the hydroxyl value, the molecular weight distribution of the system becomes wider during polymerization, and the amount of unreacted carboxylic acid residue increases locally, resulting in an increase in acid value to 0.6 mg KOH / g, and the viscosity also increases to 9333 mPa·s, which exceeds the low viscosity range of the present invention.

[0072] Comparative Example 3 lacked both bio-based polyether polyol and vegetable oil, two key components, thus disrupting the synergistic system of the four-component compound of this invention and leading to a comprehensive deterioration in performance.

[0073] (1) Viscosity control fails, resulting in extremely poor system flowability: The linear molecular structure of bio-based polyether polyols can reduce intermolecular forces within the system, while the long-chain fatty acid structure of vegetable oils can further dilute the system and break the tightness of the polymer network. Without both, the system relies solely on the reaction between bio-based polyester polyols and amine polyether polyols, leading to increased intermolecular entanglement and a viscosity soaring to 18,000 mPa·s (2.4 times that of Example 1), completely losing its flowability for practical processing applications.

[0074] (2) The acid value is seriously exceeded and the reaction is not thorough enough: Bio-based polyether polyols and vegetable oils can be used as "reaction diluents" to improve the reactivity of hydroxyl groups in bio-based polyester polyols and promote the thorough transesterification reaction. After the absence of both, some carboxylic acid groups failed to fully participate in the alcohol-acid condensation reaction, and the acid value soared to 1.7 mgKOH / g (far exceeding the standard of ≤1 mgKOH / g of this invention). Moreover, the residual carboxylic acid will inhibit the subsequent curing reaction with MDI, extending the curing time to 30 h.

[0075] The absence of vegetable oil in Comparative Example 4 did not lead to a complete collapse in performance, but it disrupted the viscosity-reactivity balance of the system.

[0076] (1) Lack of viscosity regulation function: The long-chain aliphatic hydrocarbon structure of vegetable oil can effectively "spread" the distance between oligomer molecules, reducing intermolecular hydrogen bonding and friction. After this loss, the system relies solely on bio-based polyether polyols to regulate viscosity, which is insufficient, resulting in a viscosity increase from 7423 mPa·s to 12523 mPa·s and a significant decrease in fluidity.

[0077] (2) Slight decrease in reactivity: The ester groups in vegetable oils can undergo a small amount of transesterification with the hydroxyl groups of bio-based polyester polyols and bio-based polyether polyols, which helps to optimize the molecular chain structure and increase the density of reaction sites with MDI. After the loss of MDI, the number of reaction sites is slightly reduced, the curing time is extended from 20h to 24h, and the reaction efficiency decreases.

[0078] In summary, the superior performance of the oligomeric polyols prepared by this invention stems from the synergistic effect of the four-component compound (bio-based polyester polyols, bio-based polyether polyols, vegetable oils, and amine polyether polyols) and the stepwise process (staged heating + vacuuming). However, Comparative Examples 1-4 either violated the process design or lacked key components, thus disrupting this synergistic system and ultimately leading to performance degradation.

Claims

1. A low-viscosity oligomeric polyol with high bio-based content, characterized in that, It is prepared by transesterification of the following raw materials in parts by weight: 40-60 parts of bio-based polyester polyol, 20-30 parts of bio-based polyether polyol, 20-30 parts of vegetable oil, 3-5 parts of amine polyether polyol, catalyst, and composite antioxidant; wherein, the amine polyether polyol is a polyether polyol prepared by initiating propylene oxide with amine compounds as initiators; A method for preparing low-viscosity oligomeric polyols with high bio-based content includes the following steps: S1: Add bio-based polyester polyol, bio-based polyether polyol, catalyst and composite antioxidant into the reactor, stir at 200-300 rpm under nitrogen protection, and heat to 220-230℃ at a rate of 5-10℃ / min, and keep at the temperature for 1-2 hours. S2: Cool down to 160-180℃, add vegetable oil to the reactor, stir at the same speed, raise the temperature to 220-230℃ again, keep the temperature and draw a vacuum, and continue stirring until the system is transparent. S3: Cool down to 180-200℃, add amine polyether polyol to the reactor, keep warm for 2-4 hours, take a sample to test the acid value <1mgKOH / g and the viscosity at 25℃ <8000mPa·s, cool down to 80-100℃, release the material, and you will get a low-viscosity oligomer polyol with high bio-based content.

2. The high bio-based content, low viscosity oligomeric polyol as described in claim 1, characterized in that, The bio-based polyester polyols are polyester polyols synthesized from bio-based raw materials, with a number average molecular weight of <1000g / mol and an acid value of <2mgKOH / g.

3. The high bio-based content, low viscosity oligomeric polyol as described in claim 2, characterized in that, The bio-based polyester polyol is a polylactic acid polyol or a bio-based small molecule polyol prepared by an alkyd condensation reaction of a bio-based small molecule polyacid.

4. The high bio-based content, low viscosity oligomeric polyol as described in claim 3, characterized in that, The bio-based small molecule polyol is two of bio-based ethylene glycol, propylene glycol, and glycerol; the bio-based small molecule polyacid is one or two of succinic acid, sebacic acid, and itaconic acid.

5. The high bio-based content, low viscosity oligomeric polyol as described in claim 1, characterized in that, The bio-based polyether polyol is a polytrimethylene ether diol polyether polyol with a number average molecular weight of <1000 g / mol synthesized from bio-based raw materials.

6. The high bio-based content, low viscosity oligomeric polyol as described in claim 1, characterized in that, The vegetable oil is castor oil, soybean oil, or palm oil.

7. The high bio-based content, low viscosity oligomeric polyol as described in claim 1, characterized in that, The hydroxyl value of the amine polyether polyol is 350-500 mg KOH / g.

8. The high bio-based content, low viscosity oligomeric polyol as described in claim 1, characterized in that, The catalyst is an organotitanium catalyst or an organobismuth catalyst, and its addition amount is 30-50 ppm of the total material; the composite antioxidant is composed of hindered phenolic antioxidant and phosphite antioxidant, and its addition amount is 1-3‰ of the total material.

9. The high bio-based content, low viscosity oligomeric polyol as described in claim 1, characterized in that, The bio-based content of the low-viscosity oligomeric polyol is above 95%, with a viscosity of <8000mPa·s at 25℃, an acid value of <1mgKOH / g, and a number-average molecular weight of 610-982g / mol.

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