Halogen-free bio-based flame-retardant polyester polyol as well as preparation method and application thereof

Abstract

The invention discloses a halogen-free bio-based flame-retardant polyester polyol, which is prepared by mixing sec with monobasic acid and binary acid, the polyester polyol with moderate crosslinking degree can be prepared by using the cyclic structure of sec and the trifunctional hydroxyl structure of sec, and the prepared flame-retardant polyester polyol has excellent performance in a V-0 grade flame-retardant test. The dependence on a toxic flame retardant is also reduced; in addition, the cyclic structure and high nitrogen content of sec-cyan help to form a more compact cross-linked network after the material is formed, the material is endowed with better tensile strength and heat resistance, and mechanical properties and flame retardant effect are both considered. Wherein part of trimethylolpropane can be used for replacing siroc, so that the cost and the performance are both considered. The invention also provides application of the halogen-free bio-based flame-retardant polyester polyol. The halogen-free bio-based flame-retardant polyester polyol and isocyanate are mixed to prepare a polyurethane material.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame retardant materials, and in particular relates to a halogen-free bio-based flame retardant polyester polyol and a preparation method and application thereof. Background Art

[0002] Traditional flame retardant technology mainly relies on external flame retardants, such as halogen compounds (bromine, chlorine) or phosphate flame retardants. Although these flame retardants can effectively improve the flame retardant properties of materials, their use brings serious environmental and health risks. Halogen flame retardants release toxic gases (such as dioxins and hydrogen halides) during combustion, which not only harms human health, but also has a long-term negative impact on the ecosystem.

[0003] As international environmental regulations become increasingly stringent, many countries and regions have begun to restrict the use of halogen flame retardants, which has promoted the research, development and application of halogen-free and additive-free flame retardant materials. Bio-based polyols have gradually become an important candidate material to replace traditional petrochemical-based polyols due to their renewability and environmentally friendly characteristics. In addition, bio-based polyols are mainly derived from renewable resources such as vegetable oils, starch and cellulose. The carbon emissions of their preparation process are low, which is also in line with the concept of low-carbon economy and green chemistry promoted globally. At present, bio-based polyols have been increasingly widely used in the fields of chemical industry and materials science, especially in the polyurethane (PU) industry. However, polyurethane materials generally have the problem of high flammability, which limits their widespread use in application fields such as construction, transportation, and electronic equipment that require high flame retardant properties. Therefore, the development of bio-based polyol materials with high flame retardant properties has become an important direction of current research.

[0004] CN115785370A discloses a bio-based polyol, and the preparation method of the bio-based flame-retardant polyurethane invented by the invention comprises the following steps: reacting allyl diethyl phosphate with 3-mercapto-1,2-propylene glycol to prepare phosphorus-containing flame-retardant polyol, reacting vegetable oil with 3-mercapto-1,2-propylene glycol to prepare bio-based polyol; reacting the phosphorus-containing flame-retardant polyol, the bio-based polyol and diisocyanate to prepare the bio-based flame-retardant polyurethane. However, the polyurethane elastomer prepared by the bio-based polyol has poor mechanical properties.

[0005] CN117402312A discloses a bio-based flame retardant polyol, specifically a castor oil-based flame retardant microporous polyurethane elastomer and a preparation method thereof. The invention uses castor oil as a raw material, prepares flame retardant castor oil polyol through a synthetic route of epoxidation and ring opening, applies castor oil flame retardant polyol grafted with DOPO to the field of polyurethane elastomer, and replaces part of the conventional chain extender with part of the terminal hydroxyl silicone chain extender. Through the synergistic effect of the terminal hydroxyl silicone chain extender and the castor oil flame retardant polyol in a certain proportion, the prepared polyurethane elastomer has excellent flame retardant properties and mechanical properties, and good rebound performance. However, this flame retardant polyol needs to add a large amount of polyol to exert the flame retardant effect, and the prepared polyurethane has a low bio-based content and poor mechanical properties.

[0006] In summary, the introduction of flame retardant elements or flame retardants (such as phosphorus or nitrogen) will change the molecular structure of polyols, and flame retardants will damage and increase the brittleness of the material. In particular, polyol materials with high flame retardancy have too high molecular crosslinking or molecular chain rigidity, which makes the material's performance in mechanical properties such as impact and stretching worse. For this reason, it is difficult to achieve an ideal balance between flame retardancy and mechanical properties, which remains the focus of technical optimization. Summary of the invention

[0007] Based on this, the purpose of the present invention is to provide a halogen-free bio-based flame-retardant polyester polyol and a preparation method thereof, which is prepared using tris(2-hydroxyethyl)isocyanurate (CYC) and bio-based monoacids and diacids, to solve the problems of existing flame retardant materials such as insufficient environmental protection, high cost, and imbalance between flame retardant properties and mechanical properties.

[0008] Part I:

[0009] A halogen-free bio-based flame-retardant polyester polyol, comprising at least one of formula I and formula II,

[0010]

[0011] Wherein, R1 is a C2-C17 hydrocarbon group; R2 is a C2-C16 alkyl group; R3 is a C3-C5 alkyl group or a C2-C8 alkyl group connected with an ester group, wherein the ester group is R1COO-; l is an integer of 2-7, m is an integer of 2-7, and n is an integer of 1-7. Preferably, l is 2 or 3, m is 2 or 3, and n is 1 or 2.

[0012] Tris(2-hydroxyethyl)isocyanurate (CYC) itself has a ring structure, which gives it excellent thermal insulation, thermal stability and mechanical properties. The high nitrogen content of CYC can generate inert gas nitrogen and water during the combustion process, which greatly prevents the continuation of the combustion reaction and enhances the self-flammability of the material; moreover, the ring structure of CYC can also effectively block heat transfer, further improving the flame retardancy of the material.

[0013] At the same time, the cyclic structure of Cyclic and its trifunctional hydroxyl structure can prepare polyester polyols with moderate crosslinking degree (as shown in Formula I), which take into account both mechanical properties and flame retardant effects. Cyclic ring structure and high nitrogen content help the material form a denser crosslinking network after molding, giving the material better tensile strength and heat resistance; Cyclic trihydroxy structure significantly enhances the mechanical properties of polyester polyols, especially in key properties such as elasticity and toughness.

[0014] In addition, since Cyclic itself provides a strong flame retardant mechanism, the bio-based polyester polyol in the present invention does not need to be added with chemical flame retardants, which not only reduces the use of toxic substances, but also avoids the impact of additives on the mechanical properties of the material. Therefore, the flame retardant and mechanical properties of the present invention can be kept stable and consistent, and are particularly suitable for application scenarios with high requirements for flame retardancy and mechanical properties, such as building materials and automotive interiors.

[0015] Part II:

[0016] A method for preparing the halogen-free bio-based flame-retardant polyester polyol as described in the first part comprises the following steps:

[0017] Mix sike and monoacid in a molar ratio of 1:(0.4-1.3), add a first catalyst, evacuate, react at a temperature of 180-240°C for 3-16 hours, then add a dibasic acid and continue to react for 3-16 hours, the molar ratio of the dibasic acid added to the sike is (0.2-0.9):1, and obtain the halogen-free bio-based flame-retardant polyester polyol of formula I; the first catalyst includes at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, titanate ester, tetrabutyl zirconate, tetraisopropyl zirconate, dibutyl tin dilaurate and antimony zinc oxide.

[0018] The present invention introduces nitrogen into the molecular structure, which generates nitrogen and water during combustion, giving the material self-flame retardant properties. Experimental results show that the prepared flame-retardant polyester polyol performs well in the V-0 grade flame retardant test while maintaining high mechanical properties. This invention not only reduces the flammability of the material, but also reduces the dependence on toxic flame retardants, meets the needs of sustainable development, and has good application prospects in high-demand fields such as construction and automotive interiors; when synthesizing polyester polyols, no reaction occurs if the temperature is too low, and too high a temperature will cause the product to decompose.

[0019] A method for preparing the halogen-free bio-based flame-retardant polyester polyol as described in the first part comprises the following steps:

[0020] The mixture is mixed with a small molecule polyol in a molar ratio of 1:(0.1-1.5) to obtain a blend A, and then the blend A and a monoacid in a molar ratio of 1:(0.4-1.3) are mixed, a first catalyst is added, vacuum is drawn, and the mixture is reacted at a temperature of 180-240° C. for 3-16 hours, and then a diacid is added to continue the reaction for 3-16 hours, wherein the molar ratio of the diacid addition amount to the blend A is (0.2-0.9):1, to obtain The halogen-free bio-based flame-retardant polyester polyol of formula II is obtained; the small molecule polyol includes at least one of 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, glycerol, trimethylolpropane, trimethylolethane, sorbitol, and pentaerythritol; the first catalyst includes at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, titanate, tetrabutyl zirconate, tetraisopropyl zirconate, dibutyltin dilaurate, and antimony zinc oxide.

[0021] In order to reduce production costs, small molecule polyols are partially used to replace Cyc. In the examples of this application, trimethylolpropane (TMP) is used to replace Cyc. Like Cyc, TMP also has trifunctional hydroxyl groups and can react with organic acids. In addition, TMP can also reduce the viscosity of the flame retardant polyol, which is convenient for subsequent construction. The flame retardant properties and mechanical properties of the bio-based flame retardant polyester polyol (as shown in Formula II) prepared by block blending Cyc and TMP through covalent bond connection are still maintained at a high level, achieving a balance between cost and performance.

[0022] As a preferred embodiment, the monoacid includes at least one of dodecanoic acid, acetic acid, butyric acid, caproic acid, capric acid, linoleic acid, linolenic acid, oleic acid and stearic acid; the diacid includes at least one of amber acid, glutaric acid, pimelic acid, maleic anhydride ring-opening product, azelaic acid, dodecanedioic acid, 2,5-furandicarboxylic acid, terephthalic acid, dimer acid, adipic acid and sebacic acid. More preferably, the monoacid is oleic acid and stearic acid, and the diacid is adipic acid and sebacic acid. Bio-based oleic acid and stearic acid are used to increase the bio-based content of the product, reduce the use of petrochemical-based materials, and reduce carbon emissions. Compared with stearic acid and oleic acid, that is, compared with alkanoic acid and alkene acid, the prepared flame-retardant polyester polyol has an increased elongation at break, a high breaking stress, and an unaffected flame retardant effect. Bio-based adipic acid and sebacic acid are used to increase the bio-based content of the product, reduce the use of petrochemical-based materials, and lower carbon emissions; as the carbon chain of the dibasic acid becomes longer, the elongation at break of the flame-retardant polyester polyol increases, the breaking stress decreases, the overall flexibility increases, and the flame retardant effect is not affected.

[0023] As a preferred embodiment, when the acid value is lower than 3 mg KOH / g, the dibasic acid is added, and then when the acid value is lower than 3 mg KOH / g and the hydroxyl value reaches 40-70 mg KOH / g, the reaction is terminated. If the acid value and hydroxyl value are too high or too low, the obtained polyester polyol will cause poor mechanical properties and poor flame retardant properties in the subsequent synthesis of polyurethane.

[0024] Part III:

[0025] A polyurethane material is prepared from the halogen-free bio-based flame-retardant polyester polyol described in the first part.

[0026] Part 4:

[0027] A method for preparing the polyurethane material as described in the third part comprises the following steps:

[0028] The first polyol and the isocyanate are mixed and reacted at 50 to 90° C. for 1 to 3 hours to obtain a polyurethane prepolymer;

[0029] The polyurethane prepolymer is mixed with the second polyol, a second catalyst is added, the mixture is stirred and mixed, and the mixture is reacted at 60 to 120° C. for 10 to 16 hours to obtain a polyurethane material;

[0030] Wherein, the first polyol comprises a halogen-free bio-based flame-retardant polyester polyol; the first polyol is calculated as a hydroxyl group, the isocyanate is calculated as an NCO group, and the molar ratio of the hydroxyl group to the NCO group is 1:(1-1.3); the second catalyst comprises at least one of organic tin, organic amine, organic mercury and organic bismuth, and the content of cyanate is ≥12wt.%, wherein the cyanate content refers to the percentage of the weight of the raw material cyanate involved in the preparation reaction of the halogen-free bio-based flame-retardant polyester polyol to the weight of the polyurethane material.

[0031] When synthesizing polyurethane prepolymers, if the temperature is too low, the reaction will be extremely slow, which will increase the cost; if the temperature is too high, violent polymerization will occur; if the time is too short, sufficient polymerization will not be possible; and if the time is too long, the cost will increase; when synthesizing polyurethane materials, if the temperature is too low, the reaction will be extremely slow, which will increase the cost; if the temperature is too high, the mechanical properties and flame retardant properties of the product will deteriorate; if the time is too low, the product performance will be poor; and if the time is too high, the cost will increase.

[0032] As a preferred embodiment, the isocyanate includes at least one of Wanhua Chemical PM200, isophorone diisocyanate (IPDI) and 4,4-diphenylmethane diisocyanate (MDI). They are commonly used in industry, have good yellowing resistance and low price.

[0033] As a preferred solution, the amount of the second catalyst added is 0.001 to 0.1 wt.% of the polyurethane prepolymer.

[0034] As a preferred embodiment, the second polyol includes at least one of 1,4-butanediol (BDO), ethylene glycol (EG), diethylene glycol (DEG), 1,3-propylene glycol (PDO) and 2-methyl-1,3-propanediol (MPDO), and the molar ratio of the polyurethane prepolymer to the polyol is 1:1 to 1.3. The small molecule second polyol is used as a chain extender for the polyurethane. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Infrared characterization images of FR01, TMP-polyol and FR01-b-TMP-2;

[0036] Figure 2 is the stress-strain curve of samples 1-9;

[0037] Figure 3 is the stress-strain curve of sample 10-11;

[0038] Figure 4 is the stress-strain curve of sample 12-14;

[0039] Figure 5 is the stress-strain curve of sample 15-16;

[0040] Figure 6 is the stress-strain curve of samples 17-19;

[0041] Figure 7 The stress-strain curves of samples 13 and 20. DETAILED DESCRIPTION

[0042] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0043] The molar ratio of sike and monoacid is 1:(0.4-1.3), and the first catalyst is added. The mixture is vacuumized and reacted at a temperature of 180-240°C for 3-16 hours. When the acid value is lower than 3 mg KOH / g, a dibasic acid is added to continue the reaction for 3-16 hours. The molar ratio of the dibasic acid added to sike is (0.2-0.9):1. When the acid value is lower than 3 mg KOH / g and the hydroxyl value reaches 40-70 mg KOH / g, the reaction is terminated to obtain the halogen-free bio-based flame-retardant polyester polyol (as shown in Formula I); the first catalyst includes at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, titanate, tetrabutyl zirconate, tetraisopropyl zirconate, dibutyl tin dilaurate and antimony zinc oxide.

[0044]

[0045] The molar ratio of sike and small molecule polyol is 1: (0.1-1.5) to obtain blend A, and then the blend A and monoacid are mixed in a molar ratio of 1: (0.4-1.3), a first catalyst is added, vacuum is evacuated, and the mixture is reacted at a temperature of 180-240° C. for 3-16 hours. When the acid value is lower than 3 mg KOH / g, a dibasic acid is added and the reaction is continued for 3-16 hours. The molar ratio of the dibasic acid addition amount to the blend A is (0.2-0.9): 1. When the acid value is lower than 3 mg KOH / g and the hydroxyl value reaches 40-70 mg KOH / g, the reaction is terminated to obtain the halogen-free bio-based flame-retardant polyester polyol (as shown in Formula II). The small molecule polyol includes at least one of 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, glycerol, trimethylolpropane, trimethylolethane, sorbitol, and pentaerythritol; the first catalyst includes at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, titanate, tetrabutyl zirconate, tetraisopropyl zirconate, dibutyltin dilaurate, and antimony zinc oxide.

[0046]

[0047] Wherein, R1 is a C2-C17 hydrocarbon group; R2 is a C2-C16 alkyl group; R3 is a C3-C5 alkyl group or a C2-C8 alkyl group connected with an ester group, wherein the ester group is R1COO-; l is an integer of 2-7, m is an integer of 2-7, and n is an integer of 1-7. Preferably, l is 2 or 3, m is 2 or 3, and n is 1 or 2.

[0048] A method for preparing a polyurethane material comprises the following steps:

[0049] The halogen-free bio-based flame-retardant polyester polyol is mixed with isocyanate, and reacted at 50 to 90° C. for 1 to 3 hours to obtain a polyurethane prepolymer;

[0050] The polyurethane prepolymer is mixed with the polyol, a second catalyst is added, the mixture is stirred and mixed, and the mixture is reacted at 60 to 120° C. for 10 to 16 hours to obtain a polyurethane material;

[0051] Wherein, the halogen-free bio-based flame-retardant polyester polyol is calculated based on hydroxyl groups, and the isocyanate is calculated based on NCO groups, and the molar ratio of the hydroxyl groups to the NCO groups is 1:1.05; the second catalyst includes at least one of dibutyltin dilaurate, dibutyltin dioctoate, organic tin trichloride, triethylenediamine, dimethylaminoethanol, N-methylmorpholine, bis[2-(dimethylamino)ethyl]ether, phenylmercuric acetate, phenylmercuric sulfate, bis(2-ethylhexanoate) bismuth, tri(2-ethylhexanoate) bismuth and bismuth-zinc composite catalyst; the sike content is ≥12wt.%, wherein the sike content refers to the percentage of the weight of the raw material sike involved in the preparation reaction of the halogen-free bio-based flame-retardant polyester polyol to the weight of the polyurethane material.

[0052] The isocyanate includes at least one of Wanhua Chemical PM200, isophorone diisocyanate (IPDI) and 4,4'-diphenylmethane diisocyanate (MDI); the added amount of the second catalyst is 0.1 to 1.0 wt.% of the polyurethane prepolymer; the polyol includes at least one of 1,4-butanediol (BDO), ethylene glycol (EG), diethylene glycol (DEG), 1,3-propylene glycol (PDO) and 2-methyl-1,3-propanediol (MPDO), and the molar ratio of the polyurethane prepolymer to the polyol is 1:1 to 1.3.

[0053] Example 1

[0054] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0055] 187.5g vegetable oil acid and 173.4g Sec were mixed, tetrabutyl titanate was added as a catalyst, vacuum was drawn, and the reaction was carried out at a temperature of 180-240°C for 3-16h. Then 67.8g adipic acid was added, the vacuum was continued, and the reaction was carried out for 3-16h to prepare halogen-free bio-based flame-retardant polyester polyol FR01. After the reaction, the acid value and hydroxyl value were measured, and they were packaged if they met the requirements.

[0056] FR01 was characterized by infrared spectroscopy (FTIR) analysis. The characterization results are shown in Figure 1 As shown. In the spectrum, the characteristic absorption peak of the carbonyl group (C=O) appears in the range of 1650-1780cm-1, indicating that the hydroxyl group in the raw material has undergone esterification with the carboxylic acid group. At the same time, a broad peak absorption is observed in the characteristic range of 3200-3600cm-1 of the terminal hydroxyl group, further proving that the hydroxyl functional groups are retained at both ends of the polyol molecule. This result confirms the completion of the esterification reaction and the characteristic structure of the polyol. The structural formula of FR01 is shown in Formula I.

[0057]

[0058]

[0059] In addition, the endpoint of the reaction was determined by hydroxyl value and acid value titration. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, further verifying the completion of the esterification reaction and the formation of the polyol structure.

[0060] Example 2

[0061] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0062] 187.5g vegetable oil acid and 173.4g sike were mixed, tetrabutyl titanate was added as a catalyst, vacuum was drawn, and the mixture was reacted at a temperature of 180-240°C for 3-16h. Then 93.8g sebacic acid was added, vacuum was drawn again, and the mixture was reacted for 3-16h to finally prepare halogen-free bio-based flame-retardant polyester polyol FR01-Dec. After the reaction, the acid value and hydroxyl value were measured, and they were packaged if they met the requirements.

[0063] The endpoint of the reaction was determined by titration of hydroxyl value and acid value. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, verifying the completion of the esterification reaction and the formation of the structure of the polyol.

[0064] Example 3

[0065] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0066] 188.8g of stearic acid and 173.4g of Sec were mixed, tetrabutyl titanate was added as a catalyst, vacuum was drawn, and the mixture was reacted at a temperature of 180-240°C for 3-16h. Then 67.8g of adipic acid was added, vacuum was drawn again, and the mixture was reacted for 3-16h to finally prepare halogen-free bio-based flame-retardant polyester polyol FR01-Stc. After the reaction, the acid value and hydroxyl value were measured, and they were packaged if they met the requirements.

[0067] The endpoint of the reaction was determined by titration of hydroxyl value and acid value. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, verifying the completion of the esterification reaction and the formation of the structure of the polyol.

[0068] Example 4

[0069] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0070] 187.5g of vegetable oil acid, 86.7g of sike and 44.4g of TMP were mixed, tetrabutyl titanate was added as a catalyst, vacuum was drawn, and the mixture was reacted at a temperature of 180-240°C for 3-16h. Then 67.8g of adipic acid was added, vacuum was drawn again, and the mixture was reacted for 3-16h to finally prepare halogen-free bio-based flame-retardant polyester polyol FR01-b-TMP-1. After the reaction, the acid value and hydroxyl value were measured, and they were packaged if they met the requirements.

[0071] The endpoint of the reaction was determined by hydroxyl value and acid value titration. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, further verifying the completion of the esterification reaction and the formation of the polyol structure.

[0072] Example 5

[0073] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0074] 187.5g of vegetable oil acid, 69.4g of sike and 53.4g of TMP were mixed, tetrabutyl titanate was added as a catalyst, vacuum was drawn, and the mixture was reacted at a temperature of 180-240°C for 3-16h. Then 67.8g of adipic acid was added, vacuum was drawn again, and the mixture was reacted for 3-16h to finally prepare halogen-free bio-based flame-retardant polyester polyol FR01-b-TMP-2. After the reaction, the acid value and hydroxyl value were measured, and they were packaged if they met the requirements.

[0075] FR01-b-TMP-2 was characterized by infrared spectroscopy (FTIR) analysis. The characterization results are shown in Figure 1 As shown. In the spectrum, the characteristic absorption peak of the carbonyl group (C=O) appears in the range of 1650-1780cm-1, indicating that the hydroxyl group in the raw material has undergone esterification with the carboxylic acid group. At the same time, a broad peak absorption is observed in the characteristic range of 3200-3600cm-1 of the terminal hydroxyl group, further proving that the hydroxyl functional groups are retained at both ends of the polyol molecule. This result confirms the completion of the esterification reaction and the characteristic structure of the polyol. The structure of FR01-b-TMP-2 is shown in Formula II.

[0076]

[0077] In addition, the endpoint of the reaction was determined by hydroxyl value and acid value titration. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, further verifying the completion of the esterification reaction and the formation of the polyol structure.

[0078] Example 6

[0079] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0080] 187.5g of vegetable oil acid, 60.7g of sike and 57.9g of TMP were mixed, tetrabutyl titanate was added as a catalyst, vacuum was drawn, and the mixture was reacted at a temperature of 180-240°C for 3-16h. Then 67.8g of adipic acid was added, vacuum was drawn again, and the mixture was reacted for 3-16h to finally prepare halogen-free bio-based flame-retardant polyester polyol FR01-b-TMP-3. After the reaction, the acid value and hydroxyl value were measured, and they were packaged if they met the requirements.

[0081] The endpoint of the reaction was determined by hydroxyl value and acid value titration. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, further verifying the completion of the esterification reaction and the formation of the polyol structure.

[0082] Example 7

[0083] A method for preparing a halogen-free bio-based flame-retardant polyester polyol comprises the following steps:

[0084] 75.1g vegetable oil acid, 69.4g cycerol and 35.9g BDO were mixed, tetrabutyl titanate was added as a catalyst, vacuum was drawn, and the mixture was reacted at a temperature of 180-240°C for 3-16h. Then 67.8g adipic acid was added, vacuum was drawn again, and the mixture was reacted for 3-16h to finally prepare halogen-free bio-based flame-retardant polyester polyol FR01-b-BDO-4. After the reaction, the acid value and hydroxyl value were measured, and they were packaged if they met the requirements.

[0085] The endpoint of the reaction was determined by hydroxyl value and acid value titration. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, further verifying the completion of the esterification reaction and the formation of the polyol structure.

[0086] Comparative Example 1

[0087] A method for preparing polyol TMP-polyol comprises the following steps:

[0088] 187.5g vegetable oil acid and 89.1g TMP are mixed, tetrabutyl titanate is added as a catalyst, vacuum is applied, and the mixture is reacted at a temperature of 180-240°C for 3-16h. Then 67.8g adipic acid is added, vacuum is applied, and the mixture is reacted for 3-16h to finally prepare polyol TMP-polyol. After the reaction, the acid value and hydroxyl value are measured, and the mixture is packaged if the requirements are met.

[0089] TMP-polyol was characterized by infrared spectroscopy (FTIR) analysis. The characterization results are as follows: Figure 1As shown. In the spectrum, the characteristic absorption peak of the carbonyl group (C=O) appears in the range of 1650-1780cm-1, indicating that the hydroxyl group in the raw material has undergone esterification with the carboxylic acid group. At the same time, a broad peak absorption is observed in the characteristic range of 3200-3600cm-1 of the terminal hydroxyl group, further proving that the hydroxyl functional groups are retained at both ends of the polyol molecule. This result confirms the completion of the esterification reaction and the formation of the characteristic structure of the polyol.

[0090] In addition, the endpoint of the reaction was determined by hydroxyl value and acid value titration. The experimental results showed that as the reaction proceeded, the acid value gradually decreased, while the hydroxyl value gradually increased, and finally both were close to the theoretical design value, further verifying the completion of the esterification reaction and the formation of the polyol structure.

[0091] A method for preparing a polyurethane material comprises the following steps:

[0092] 4.5 g of TMP-polyol was mixed with 1.4 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain sample 1.

[0093] Comparative Example 2

[0094] A method for preparing a polyurethane material comprises the following steps:

[0095] 1.1 g of FR01 polyol prepared in Example 1, 3.6 g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4 g of PM200 were mixed and reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 2.

[0096] Comparative Example 3

[0097] A method for preparing a polyurethane material comprises the following steps:

[0098] 1.96 g of FR01 polyol prepared in Example 1, 2.9 g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4 g of PM200 were mixed and reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain sample 3.

[0099] Comparative Example 4

[0100] A method for preparing a polyurethane material comprises the following steps:

[0101] 2.2 g of FR01 polyol prepared in Example 1, 2.7 g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4 g of PM200 were mixed and reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 4.

[0102] Example 8

[0103] A method for preparing a polyurethane material comprises the following steps:

[0104] Take 2.5g of FR01 polyol prepared in Example 1, 2.5g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4g of PM200, mix them, react at 80°C for 2h to obtain a polyurethane prepolymer, then mix the obtained polyurethane prepolymer with 0.2g of BDO, add 0.06wt.% of organic tin catalyst, blend in a high-speed mixer, pour into a mold, and mature for 10-16h to obtain Sample 5.

[0105] Example 9

[0106] A method for preparing a polyurethane material comprises the following steps:

[0107] Take 2.8g of FR01 polyol prepared in Example 1, 2.3g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4g of PM200, mix them, react at 80°C for 2h to obtain a polyurethane prepolymer, then mix the obtained polyurethane prepolymer with 0.2g of BDO, add 0.06wt.% of organic tin catalyst, blend in a high-speed mixer, pour into a mold, and mature for 10-16h to obtain Sample 6.

[0108] Example 10

[0109] A method for preparing a polyurethane material comprises the following steps:

[0110] 3.4 g of FR01 polyol prepared in Example 1, 1.8 g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4 g of PM200 were mixed and reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 7.

[0111] Embodiment 11

[0112] A method for preparing a polyurethane material comprises the following steps:

[0113] 4.5 g of FR01 polyol prepared in Example 1, 0.9 g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4 g of PM200 were mixed and reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 8.

[0114] Example 12

[0115] A method for preparing a polyurethane material comprises the following steps:

[0116] 5.6 g of FR01 polyol prepared in Example 1, 1.4 g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4 g of PM200 were mixed and reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 9.

[0117] Embodiment 13

[0118] A method for preparing a polyurethane material comprises the following steps:

[0119] 5.8 g of the FR01-Dec polyol prepared in Example 2 was mixed with 1.4 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 10.

[0120] Embodiment 14

[0121] A method for preparing a polyurethane material comprises the following steps:

[0122] 5.7 g of the FR01-Stc polyol prepared in Example 3 was mixed with 1.4 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 11.

[0123] Embodiment 15

[0124] A method for preparing polyurethane comprises the following steps:

[0125] 5 g of the FR01-b-TMP-1 polyol prepared in Example 4 was mixed with 1.4 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 12.

[0126] Example 16

[0127] A method for preparing a polyurethane material comprises the following steps:

[0128] 4.9 g of FR01-b-TMP-2 polyol prepared in Example 5 was mixed with 1.4 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 13.

[0129] Comparative Example 5

[0130] A method for preparing a polyurethane material comprises the following steps:

[0131] 4.8 g of the FR01-b-TMP-3 polyol prepared in Example 6 was mixed with 1.4 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 14.

[0132] Embodiment 17

[0133] A method for preparing a polyurethane material comprises the following steps:

[0134] Take 2.5g of FR01 polyol prepared in Example 1, 2.5g of TMP-polyol polyol prepared in Comparative Example 1, and 1.2g of isophorone diisocyanate (IPDI), mix them, and react them at 80°C for 2h to obtain a polyurethane prepolymer. Then mix the obtained polyurethane prepolymer with 0.2g of BDO, add 0.06wt.% of an organic tin catalyst, blend them in a high-speed mixer, pour them into a mold, and mature them for 10-16h to obtain Sample 15.

[0135] Embodiment 18

[0136] A method for preparing a polyurethane material comprises the following steps:

[0137] Take 2.5g of FR01 polyol prepared in Example 1, 2.5g of TMP-polyol polyol prepared in Comparative Example 1, and 1.3g of 4,4'-diphenylmethane diisocyanate (MDI), react at 80°C for 2h to obtain a polyurethane prepolymer, then mix the obtained polyurethane prepolymer with 0.2g of BDO, add 0.06wt.% of an organic tin catalyst, blend in a high-speed mixer, pour into a mold, and mature for 10-16h to obtain Sample 16.

[0138] Comparative Example 6

[0139] A method for preparing a polyurethane material comprises the following steps:

[0140] Take 5.4g of FR01 polyol prepared in Example 1, 3.5g of TMP-polyol polyol prepared in Comparative Example 1, and 1.4g of PM200, mix them, react at 80°C for 2h to obtain a polyurethane prepolymer, then add 0.06wt.% of an organic tin catalyst, blend in a high-speed mixer, pour into a mold, and mature for 10-16h to obtain sample 17.

[0141] Comparative Example 7

[0142] A method for preparing polyurethane comprises the following steps:

[0143] 4.3 g of the FR01 polyol prepared in Example 1 was mixed with 2.7 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.1 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 18.

[0144] Comparative Example 8

[0145] A method for preparing a polyurethane material comprises the following steps:

[0146] 1.8 g of the FR01 polyol prepared in Example 1 was mixed with 1.3 g of PM200, and the mixture was reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.3 g of BDO, and 0.06 wt.% of an organic tin catalyst was added. The mixture was blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 19.

[0147] Embodiment 19

[0148] A method for preparing polyurethane comprises the following steps:

[0149] 4.5 g of FR01-b-BDO-4 polyol prepared in Example 7 was mixed with 1.4 g of PM200, and reacted at 80° C. for 2 h to obtain a polyurethane prepolymer. The obtained polyurethane prepolymer was then mixed with 0.2 g of BDO, and 0.6 wt.% of an organic tin catalyst was added, blended in a high-speed mixer, poured into a mold, and aged for 10-16 h to obtain Sample 20.

[0150] Samples 1-20 were taken for flame retardancy test and mechanical property test. The stress-strain curve of mechanical property test is as follows: Figure 2-7 As shown in Table 1, the flame retardant properties and mechanical properties of samples 1-20 are shown in Table 1. Among them, the flame retardant test standard is GB / T2408-2021, and the mechanical property test standard is GB / T 528-2009. The flame retardant property of the PU prepared by the present invention is expected to reach V-0 grade, the Young's modulus reaches 1.4MPa, the breaking stress reaches 2.9MPa, the breaking elongation reaches 120%, and the toughness reaches 2.5MJ / m 3 .

[0151] Table 1 Flame retardant properties and mechanical properties of samples 1-20

[0152]

[0153] like Figure 2 As shown, samples 1-9 are PUs prepared by physically mixing FR01 and TMP-polyol. With the increase of the content of polyol FR01, the flame retardant effect, tensile strength and breaking length of the PU products are gradually increased. Therefore, for the PU prepared by physically blending FR01 and TMP-polyol, in order to make the PU flame retardant effect V0 level, the lower limit of the mass fraction of Cyc in the PU product is 15wt.%.

[0154] like Figure 3 As shown, sample 10 shows that by changing the dibasic acid in FR01 from adipic acid to sebacic acid, that is, the carbon chain length becomes longer, the elongation at break of the prepared PU increases, the breaking stress decreases, the overall flexibility of the PU increases, the mechanical properties meet the requirements, and the flame retardant effect is not affected. Sample 11 shows that by changing the monobasic acid in FR01 from oleic acid to stearic acid, the elongation at break of the prepared PU increases, the breaking stress is high, the overall mechanical properties are improved, and the flame retardant effect of the PU is not affected. Therefore, the dibasic acid and monobasic acid in FR01 are universal and can be replaced by other isobasic acids without affecting the flame retardant effect of the PU prepared by FR01.

[0155] like Figure 4As shown, samples 12-14 are PUs prepared by replacing part of Cyc with block polyols of TMP in FR01 (i.e., Cyc and TMP are bonded by covalent bonds). As the Cyc content in polyol FR01 decreases, the flame retardant effect, tensile strength and elongation at break of the PU products gradually decrease. In addition, from the perspective of flame retardant effect, for PU prepared by block blending Cyc and TMP in FR01 connected by covalent bonds, the lower limit of the mass fraction of Cyc in PU products is 12wt.% in order to achieve V0 flame retardant effect of PU.

[0156] like Figure 5 As shown, samples 15-16 are prepared with FR01 as the soft segment and IPDI and MDI as isocyanate, respectively. The flame retardant effect of PU prepared with IPDI is not affected, the tensile strength decreases, but the elongation at break increases, and the overall mechanical properties meet the requirements; the flame retardant effect of PU prepared with MDI is not affected, the tensile strength increases, but the elongation at break decreases, and the overall mechanical properties meet the requirements. It can be seen that the mechanical properties of PU prepared with different isocyanates using FR01 as the soft segment will be affected by the type of isocyanate, but the overall mechanical properties can meet the requirements, and the flame retardant effect is not affected.

[0157] like Figure 6 As shown, samples 17-19 are PU samples with FR01 as soft segment or FR01 and TMP-polyol as soft segment, PM200 and BDO as hard segment. Although the content of cyanoacrylate is greater than 15wt.%, the flame retardant effect and elongation at break of PU decrease with the increase of hard segment content in PU. In order to make the flame retardant effect of PU reach V0 level and the mechanical properties meet the requirements, the hard segment content in PU cannot be too high.

[0158] like Figure 7 As shown, compared with sample 13, sample 20 uses 1,4-butanediol (BDO) to partially replace cyc, and the structure of the flame-retardant polyester polyol prepared (as shown in formula II) has R3 as an alkyl group. The flame retardant effect of the PU product prepared by using this flame-retardant polyester polyol can also reach V-0 level, the overall mechanical properties meet the requirements, and the elongation at break is greatly improved.

[0159] In summary, the cyanate content and hard segment content in the PU sample directly determine the flame retardant effect. The cyanate content needs to be greater than 12wt.%, and the hard segment content cannot be too high. The overall mechanical properties are affected by monoacid, diacid and isocyanate.

[0160] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A halogen-free bio-based flame retardant polyester polyol comprising at least one of formula I and formula II, in, R1 is a C2-C17 hydrocarbon group; R2 is a C2-C16 alkyl group; R3 is a C3-C5 alkyl group or a C2-C8 alkyl group connected to an ester group, wherein the ester group is R1COO-; l is an integer of 2-7, m is an integer of 2-7, and n is an integer of 1-7.

2. A method for preparing the halogen-free bio-based flame-retardant polyester polyol according to claim 1, comprising the following steps: Mix sike and monoacid in a molar ratio of 1:(0.4-1.3), add a first catalyst, evacuate, react at a temperature of 180-240°C for 3-16 hours, then add a dibasic acid and continue to react for 3-16 hours, the molar ratio of the dibasic acid added to the sike is (0.2-0.9):1, and obtain the halogen-free bio-based flame-retardant polyester polyol of formula I; the first catalyst includes at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, titanate ester, tetrabutyl zirconate, tetraisopropyl zirconate, dibutyl tin dilaurate and antimony zinc oxide.

3. A method for preparing the halogen-free bio-based flame-retardant polyester polyol according to claim 1, comprising the following steps: The molar ratio of sike and small molecule polyol is 1: (0.1-1.5) to obtain blend A, and then the blend A and monoacid are mixed at a molar ratio of 1: (0.4-1.3), and the first catalyst is added, and the mixture is vacuumed and reacted at a temperature of 180-240°C for 3-16 hours, and then a dibasic acid is added to continue the reaction for 3-16 hours, and the molar ratio of the dibasic acid addition amount to the sike is (0.2-0.9): 1 to obtain the halogen-free bio-based flame-retardant polyester polyol of formula II; the small molecule polyol includes at least one of 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, glycerol, trimethylolpropane, trimethylolethane, sorbitol, and pentaerythritol; the first catalyst includes at least one of tetrabutyl titanate, tetraisopropyl titanate, tetraoctyl titanate, titanate, tetrabutyl zirconate, tetraisopropyl zirconate, dibutyltin dilaurate, and antimony zinc oxide.

4. The method for preparing the halogen-free bio-based flame-retardant polyester polyol according to any one of claims 2 to 3, characterized in that: The monoacid includes at least one of dodecanoic acid, acetic acid, butyric acid, caproic acid, capric acid, linoleic acid, linolenic acid, oleic acid and stearic acid; the diacid includes at least one of amber acid, glutaric acid, pimelic acid, maleic anhydride ring-opening product, azelaic acid, dodecanedioic acid, 2,5-furandicarboxylic acid, terephthalic acid, dimer acid, adipic acid and sebacic acid.

5. The method for preparing the halogen-free bio-based flame-retardant polyester polyol according to any one of claims 2 to 3, characterized in that: When the acid value is lower than 3 mg KOH / g, the dibasic acid is added, and then when the acid value is lower than 3 mg KOH / g and the hydroxyl value reaches 40 to 70 mg KOH / g, the reaction is terminated.

6. A polyurethane material, characterized in that: Prepared from the halogen-free bio-based flame-retardant polyester polyol according to claim 1.

7. A method for preparing the polyurethane material according to claim 6, comprising the following steps: The first polyol and the isocyanate are mixed and reacted at 50 to 90° C. for 1 to 3 hours to obtain a polyurethane prepolymer; The polyurethane prepolymer is mixed with the second polyol, a second catalyst is added, the mixture is stirred and mixed, and the mixture is reacted at 60 to 120° C. for 10 to 16 hours to obtain a polyurethane material; in, The first polyol includes the halogen-free bio-based flame-retardant polyester polyol; the first polyol is calculated based on hydroxyl groups, the isocyanate is calculated based on NCO groups, and the molar ratio of the hydroxyl groups to the NCO groups is 1:(1-1.3); the second catalyst includes at least one of organic tin, organic amine, organic mercury and organic bismuth; the cyanate content is ≥12wt.%, wherein the cyanate content refers to the percentage of the weight of the raw material cyanate involved in the preparation reaction of the halogen-free bio-based flame-retardant polyester polyol to the weight of the polyurethane material.

8. The method for preparing the polyurethane material according to claim 7, characterized in that: The isocyanate includes at least one of Wanhua Chemical PM200, isophorone diisocyanate and 4,4'-diphenylmethane diisocyanate.

9. The method for preparing the polyurethane material according to claim 7, characterized in that: The added amount of the second catalyst is 0.001 to 0.1 wt.% of the polyurethane prepolymer.

10. The method for preparing polyurethane according to claim 7, characterized in that: The second polyol includes at least one of 1,4-butanediol, ethylene glycol, diethylene glycol, 1,3-propylene glycol and 2-methyl-1,3-propylene glycol, and the molar ratio of the polyurethane prepolymer to the polyol is 1:1 to 1.3.

Images