Bio-based polyurethane material and preparation method thereof

Abstract

The invention discloses a bio-based polyurethane material and a preparation method thereof. The preparation method comprises the following steps: 1) dissolving bis (2-hydroxyethyl) terephthalate in an organic solvent, mixing with bio-based dimer acid, adding a catalyst, and reacting at 150-170 DEG C for 4-8 hours; and carrying out subsequent treatment to obtain the bio-based polyester polyol. 2) mixing the bio-based polyol with diisocyanate and a chain extender, adding a catalyst, and reacting at 60-80 DEG C to obtain a bio-based polyurethane prepolymer; the mixing refers to stirring for 20 to 40 minutes at the temperature of 60 to 80 DEG C, and the reaction time is 1 to 3 hours; 3) mixing the bio-based polyurethane prepolymer with an internal cross-linking agent, stirring and reacting at 50-70 DEG C for 1-3 hours, and adding a diluent in the reaction process for diluting to obtain a bio-based polyurethane emulsion; and 4) carrying out film formation on the bio-based polyurethane emulsion to obtain the bio-based polyurethane material. The bio-based polyurethane material provided by the invention has excellent mechanical properties, heat resistance and biodegradability, and can be used for producing high-performance bio-based polyurethane products.

Description

Technical Field

[0001] The invention belongs to the field of bio-based polyurethane materials, and specifically relates to a bio-based polyurethane material and a preparation method thereof. Background Art

[0002] In recent years, the use of biomass resources to prepare polymer materials has attracted more and more attention. These resources are cyclically renewable and help reduce dependence on non-renewable resources such as petroleum. For example, bio-based dimer acid is derived from biomass resources in nature. It is an environmentally friendly bio-based aliphatic diacid with a wide range of applications and low prices, which can meet the needs of large-scale recycling. Therefore, the use of bio-based dimer acid to prepare bio-based polyurethane materials can significantly reduce the complexity of the target network generated by the uncertainty of the raw material biomass.

[0003] Polyethylene terephthalate (PET) is a lightweight, easy-to-process, and dimensionally stable material that is widely used in packaging bottles. With the development of society and economy, the consumption of PET packaging bottles is increasing. If they are discarded at will after use, it will not only waste resources but also cause environmental pollution. How to chemically recycle and reuse waste PET materials is one of the focuses of current attention.

[0004] Polyurethane is a polymer resin containing carbamate groups. It has good wear resistance, toughness, low-temperature flexibility, corrosion resistance and processability. It is widely used in the fields of construction, automobile industry, artificial leather, adhesives, etc. However, traditional polyurethane is mostly made from petroleum-grade raw materials and is not biodegradable and renewable. In addition, the mechanical properties and heat resistance of traditional polyurethane need to be improved.

[0005] The Chinese patent application with publication number CN115305041A discloses a method for preparing an environmentally friendly bio-based polyurethane adhesive, wherein lignin is used as a hydrogen bond donor, and a quaternary ammonium salt is used as a hydrogen bond donor to synthesize a low eutectic solvent, epoxy soybean oil is added to the solvent, and carbon dioxide is introduced to react, and a cyclic carbonate modified by lignin is synthesized at low temperature and low pressure, and then the cyclic carbonate modified by lignin is mixed with a polyamine to obtain a bio-based polyurethane adhesive. Although this method can improve the mechanical properties and heat resistance of polyurethane, this preparation method is industrially cumbersome, the preparation conditions are harsh, and only lignin belongs to the poor compatibility of rigid cross-linked phenolic macromolecules with a polymer matrix, resulting in a phase separation structure in polyurethane, and the hard segment component is too high. Therefore, the bio-based polyurethane material prepared by this method is difficult to have stable and excellent mechanical strength and heat resistance and other properties. Summary of the invention

[0006] In order to overcome the shortcomings and deficiencies of the prior art, the object of the present invention is to provide a bio-based polyurethane material and a preparation method thereof. The present invention utilizes ethylene glycol to depolymerize waste PET bottle flakes to obtain bis(2-hydroxyethyl) terephthalate (BHET), and utilizes bio-based dimer acid and BHET to react to prepare bio-based polyester polyols. The obtained bio-based polyester polyols have stable molecular weight, good heat resistance and biodegradability, and can give excellent mechanical properties, thermal stability and biodegradability to bio-based polyurethane materials. The present invention realizes the recycling of biomass resources and waste PET, and the raw material source is abundant and the price is low. The proportion of bio-based polyester polyols can be adjusted according to the needs of users, and the needs of users for the mechanical properties, heat resistance and biodegradability of bio-based polyurethane materials are met, and it has huge development potential. The bio-based polyurethane material of the present invention is applied to the fields of medical materials, food packaging materials and biodegradable ground film materials.

[0007] The purpose of the present invention is implemented through the following technical solutions.

[0008] A bio-based polyurethane material is prepared from the following raw materials in parts by weight:

[0009]

[0010]

[0011] Preferably, the bis(2-hydroxyethyl) terephthalate is obtained by depolymerization of PET; the specific preparation method comprises the following steps: in a protective atmosphere, PET and a depolymerizing agent react at 180-200° C. for 3-5 hours under the action of a catalyst, and purify the reaction to obtain a depolymerization product, bis(2-hydroxyethyl) terephthalate (BHET), wherein the depolymerizing agent is ethylene glycol.

[0012] Preferably, the mass ratio of the PET to the depolymerizing agent is 1:(2-4); the amount of the catalyst is 1-3% of the mass of the PET; the catalyst is one or more of zinc acetate, copper acetate, nickel acetate, and manganese acetate;

[0013] Preferably, the PET is waste PET;

[0014] The purification treatment refers to filtering after the reaction, rotary evaporation, cooling crystallization, centrifugal washing, and vacuum drying to obtain the depolymerization product bis(2-hydroxyethyl) terephthalate (BHET);

[0015] The bio-based dimer acid is one or more of hydrogenated dimer acid (HDA) and dimer acid (DA).

[0016] The molecular weight of the bio-based dimer acid is 400-600.

[0017] The catalyst is one or more of tetrabutyl titanate, p-toluenesulfonic acid, dibutyltin dilaurate, and dibutyltin diacetate; the organic solvent is one or more of N,N-dimethylformamide, N-methylpyrrolidone, and butanone; and the diluent is one or more of butanone, acetone, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0018] The diisocyanate is one or more of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and toluene diisocyanate;

[0019] The chain extender is one or more of bis(2-hydroxyethyl) terephthalate, 1,4-butanediol, ethylene glycol, propylene glycol, neopentyl glycol, ethanolamine, diethanolamine, and triethanolamine;

[0020] The internal cross-linking agent is one or more of trimethylolpropane, propylene glycol, glycerol and pentaerythritol.

[0021] The present invention also provides a method for preparing a bio-based polyurethane material, comprising the following steps:

[0022] 1) dissolving bis(2-hydroxyethyl) terephthalate in an organic solvent, mixing with bio-based dimer acid, adding a catalyst, reacting at 150-170° C. for 4-8 hours; and subsequently treating to obtain bio-based polyester polyol;

[0023] 2) mixing the bio-based polyol with diisocyanate and chain extender, adding a catalyst, and reacting at 60-80° C. to obtain a bio-based polyurethane prepolymer; the mixing refers to stirring at 60-80° C. for 20-40 minutes, and the reaction time is 1 to 3 hours;

[0024] 3) mixing the bio-based polyurethane prepolymer with the internal cross-linking agent, stirring and reacting at 50-70° C. for 1-3 hours, and adding a diluent to dilute the reaction to obtain a bio-based polyurethane emulsion;

[0025] 4) Forming a film of the bio-based polyurethane emulsion to obtain a bio-based polyurethane material.

[0026] Preferably, in step 1), bis(2-hydroxyethyl) terephthalate is dissolved in an organic solvent, mixed with bio-based dimer acid in an alcohol-acid molar ratio of 1.5:1, a catalyst is added, and the mixture is reacted at 150-170° C. for 4-8 hours; and subsequently treated to obtain bio-based polyester polyol.

[0027] The organic solvent described in step 1) is one or more of N,N-dimethylformamide, N-methylpyrrolidone and butanone.

[0028] The weight ratio of the organic solvent to bis(2-hydroxyethyl)terephthalate in step 1) is (12-18):(4-6).

[0029] The catalyst in step 1) is one or more of tetrabutyl titanate, p-toluenesulfonic acid, dibutyltin dilaurate, and dibutyltin diacetate; the amount of the catalyst used is 1-3% of the mass of the bio-based dimer acid.

[0030] The subsequent treatment described in step 1) refers to dissolving in chloroform and precipitating in methanol after the reaction is completed to obtain purified bio-based polyester polyol.

[0031] The amount of the catalyst used in step 2) is 1-3% of the mass of the bio-based polyester polyol.

[0032] The stirring speed in step 2) is 50-150 rpm.

[0033] The stirring speed in step 3) is 100-200 rpm.

[0034] The film forming conditions in step 4) are drying at 60-80°C for 8-12 hours.

[0035] In the bio-based polyurethane material of the present invention, the bio-based polyester polyol contains bis(2-hydroxyethyl) terephthalate (BHET) with a rigid benzene ring, which gives the bio-based polyurethane material a certain strength and heat resistance. In addition, the dimer acid containing a long chain structure in the bio-based polyol gives the bio-based polyurethane material a certain flexibility. At the same time, the bio-based polyester polyol gives the polyurethane a certain biodegradability, BHET acts as a chain extender as a hard segment of the polyurethane to give the polyurethane material a certain molecular weight, and the internal cross-linking agent gives the bio-based polyurethane material a certain toughness.

[0036] The present invention measures the molecular weight of bio-based polyurethane materials by gel permeation chromatography.

[0037] The present invention measures the mechanical properties of the bio-based polyurethane material by a tensile test method.

[0038] The present invention measures the thermal stability of bio-based polyurethane materials by thermogravimetric method.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The bio-based polyester polyol used in the present invention is completely derived from waste PET and biomass resources, and can fully realize the recycling of waste polyester and biomass resources.

[0041] 2. The biopolyester polyol used in the present invention has a rigid benzene ring structure and a flexible long-chain structure, which endows the bio-based polyurethane material with excellent mechanical properties, heat resistance and biodegradability, and can be used to produce high-performance bio-based polyurethane products.

[0042] 3. The BHET used in the present invention is not only used as a synthetic raw material for bio-based polyester polyols, but also as a chain extender for synthesizing bio-based polyurethanes, which fully realizes the high-value utilization of waste PET materials. In addition, BHET with a benzene ring structure can also give polyurethane a certain strength as a chain extender.

[0043] 4. The bio-based polyurethane material of the present invention is easy to prepare, efficient, has uniform molecular weight, and good film-forming properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flow chart for the preparation of bio-based polyester polyols;

[0045] Figure 2 is the molecular weight distribution diagram of bio-based polyester polyol;

[0046] Figure 3 This is a process flow chart for preparing bio-based polyurethane materials;

[0047] Figure 4 The mechanical properties diagram of the bio-based polyurethane materials prepared in Examples 1 to 4;

[0048] Figure 5 This is a graph showing the thermal stability of the bio-based polyurethane materials prepared in Examples 1 to 4. DETAILED DESCRIPTION

[0049] The specific implementation of the present invention is further described below in conjunction with examples, but the implementation of the present invention is not limited thereto.

[0050] Figure 1 The preparation flow chart of bio-based polyester polyols is a bio-based polyester polyol prepared by the reaction of bio-based hydrogenated dimer acid HDA and bis(2-hydroxyethyl) terephthalate BHET.

[0051] Figure 2 The molecular weight distribution diagram of the bio-based polyester polyol is the molecular weight distribution diagram of the bio-based polyester polyol prepared by reacting bio-based hydrogenated dimer acid HDA and bis(2-hydroxyethyl) terephthalate BHET according to an alcohol-acid ratio of 1.5:1.

[0052] Figure 3 The flowchart of the preparation of bio-based polyurethane materials in Examples 1 to 4 represents the reaction mechanism of different bio-based polyester polyol dosages.

[0053] Figure 4The mechanical properties diagram of the bio-based polyurethane materials prepared in Examples 1 to 4 represents the mechanical properties of the bio-based polyurethane materials prepared with different amounts of bio-based polyester polyols;

[0054] Figure 5 The thermal stability performance graph of the bio-based polyurethane materials prepared in Examples 1 to 4 represents the thermal stability performance of the bio-based polyurethane materials prepared with different amounts of bio-based polyester polyols;

[0055] Example 1

[0056] (1) Waste PET bottle flakes and ethylene glycol are mixed in a mass ratio of 1:3 and 2 wt% of a catalyst zinc acetate (2% of the mass of the waste PET) are added to a reaction container, stirred and reacted at 190° C. for 4 h, and the product is filtered, rotary evaporated, cooled and crystallized, centrifuged and washed, and vacuum dried to obtain a depolymerized monomer bis(2-hydroxyethyl) terephthalate (BHET).

[0057] (2) According to the alcohol-acid molar ratio of 1.5:1, 5.35 parts by weight of bis(2-hydroxyethyl) terephthalate (BHET) was dissolved in 16 parts by weight of N,N-dimethylformamide, and added to the reactor, and then 8 parts by weight of bio-based hydrogenated dimer acid (HDA) and 0.16 parts by weight of catalyst p-toluenesulfonic acid were added, and stirred at 160°C and 150 rpm for 6 hours, the product was dissolved in chloroform, and then the mixture was dropped into methanol and stirred until the bio-based polyester polyol was completely precipitated, and finally filtered and dried to obtain the purified bio-based polyester polyol.

[0058] (3) In the reactor, add 6 parts by weight of the purified bio-based polyester polyol obtained in step (2), 4 parts by weight of hexamethylene diisocyanate, and 1 part by weight of chain extender BHET, first stir at 70°C at a speed of 100 rpm for 30 min, then add 0.12 parts by weight of catalyst dibutyltin dilaurate (2 wt% of the weight of the bio-based polyester polyol), stir and react for 2 hours to obtain a bio-based polyurethane prepolymer for later use.

[0059] (4) 0.25 parts by weight of an internal crosslinking agent, trimethylolpropane, was added to the bio-based polyurethane prepolymer in step (3), and the mixture was stirred at 60° C. and 150 rpm for 2 h. During the reaction, 4 parts by weight of butanone was added for dilution to obtain a bio-based polyurethane emulsion.

[0060] (5) The prepared emulsion is evenly spread on a dry and clean mold to form a liquid layer with uniform thickness and smooth surface, and then dried in an oven at 80°C for 10 hours. The bio-based polyurethane film is obtained by peeling off the film.

[0061] The preparation flow chart of the bio-based polyester polyol in this embodiment is as follows Figure 1 As shown. Figure 1 It can be seen that the carboxyl group of HDA and the hydroxyl group of BHET can undergo polycondensation reaction to polymerize into bio-based polyester polyol. The molecular weight distribution diagram of the bio-based polyester polyol of this embodiment is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that when the alcohol-acid ratio of BHET to HAD is 1.5:1, the molecular weight distribution of the prepared bio-based polyester polyol is uniform and narrow, and the average molecular weight is 2063 g / mol. The preparation flow chart of the bio-based polyurethane material of this embodiment is as follows: Figure 3 As shown. Figure 3 It can be seen that the long straight-chain polyurethane prepolymer was first synthesized using bio-based polyester polyol, hexamethylene diisocyanate, and chain extender BHET, and then the internal cross-linking agent trimethylolpropane was added to prepare a bio-based polyurethane material with a cross-linked network structure. The mechanical properties of the bio-based polyurethane material of this embodiment are shown in FIG. Figure 4 As shown. Figure 4 It can be seen that when the amount of bio-based polyester polyol is 6 parts by weight, the tensile strength and elongation at break of the prepared bio-based polyurethane material are both the minimum, which are 8.8MPa and 341.8% respectively. In addition, with the increase in the amount of bio-based polyester polyol, the tensile strength of the bio-based polyurethane material gradually increases. When the amount of bio-based polyester polyol exceeds 6 parts by weight, the elongation at break increases significantly; when the amount of bio-based polyester polyol exceeds 8 parts by weight, the elongation at break remains basically unchanged. The thermal stability performance diagram of the bio-based polyurethane material of this embodiment is as follows Figure 5 As shown. Figure 5 It can be seen that as the amount of bio-based polyester polyol increases, the heat resistance of the bio-based polyurethane material gradually improves. When the amount of bio-based polyester polyol is 6 parts by weight, the heat resistance of the polyurethane material is the lowest, but it still shows good thermal stability.

[0062] Example 2

[0063] (1) Waste PET bottle flakes and ethylene glycol are mixed in a mass ratio of 1:3 and 2 wt% of a catalyst zinc acetate (2% of the mass of the waste PET) are added to a reaction container, stirred and reacted at 190° C. for 4 h, and the product is filtered, rotary evaporated, cooled and crystallized, centrifuged and washed, and vacuum dried to obtain a depolymerized monomer bis(2-hydroxyethyl) terephthalate (BHET).

[0064] (2) According to the alcohol-acid molar ratio of 1.5:1, 5.35 parts by weight of bis(2-hydroxyethyl) terephthalate (BHET) was dissolved in 16 parts by weight of N,N-dimethylformamide, and added to the reactor, and then 8 parts by weight of bio-based hydrogenated dimer acid (HDA) and 0.16 parts by weight of catalyst p-toluenesulfonic acid were added, and stirred at 160°C and 150 rpm for 6 hours, the product was dissolved in chloroform, and then the mixture was dropped into methanol and stirred until the bio-based polyester polyol was completely precipitated, and finally filtered and dried to obtain the purified bio-based polyester polyol.

[0065] (3) In the reactor, add 8 parts by weight of the purified bio-based polyester polyol obtained in step (2), 4 parts by weight of hexamethylene diisocyanate, and 1 part by weight of chain extender BHET, first stir at 70°C at a speed of 100 rpm for 30 min, then add 0.16 parts by weight of catalyst dibutyltin dilaurate (2 wt% of the weight of the bio-based polyester polyol), stir and react for 2 hours to obtain a bio-based polyurethane prepolymer for later use.

[0066] (4) 0.25 parts by weight of an internal crosslinking agent, trimethylolpropane, was added to the polyurethane prepolymer in step (3), and the mixture was stirred at 60° C. and 150 rpm for 2 h. During the reaction, 4 parts by weight of butanone was added for dilution to obtain a bio-based polyurethane emulsion.

[0067] (5) The prepared emulsion is evenly spread on a dry and clean mold to form a liquid layer with uniform thickness and smooth surface, and then dried in an oven at 80°C for 10 hours. The bio-based polyurethane film is obtained by peeling off the film.

[0068] The preparation flow chart of the bio-based polyester polyol in this embodiment is as follows Figure 1 As shown. Figure 1 It can be seen that the carboxyl group of HDA and the hydroxyl group of BHET can undergo polycondensation reaction to polymerize into bio-based polyester polyol. The molecular weight distribution diagram of the bio-based polyester polyol of this embodiment is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that when the alcohol-acid ratio of BHET to HAD is 1.5:1, the molecular weight distribution of the prepared bio-based polyester polyol is uniform and narrow, and the average molecular weight is 2063 g / mol. The preparation flow chart of the bio-based polyurethane material of this embodiment is as follows: Figure 3 As shown. Figure 3 It can be seen that the long straight-chain polyurethane prepolymer was first synthesized using bio-based polyester polyol, hexamethylene diisocyanate, and chain extender BHET, and then the internal cross-linking agent trimethylolpropane was added to prepare a bio-based polyurethane material with a cross-linked network structure. The mechanical properties of the bio-based polyurethane material of this embodiment are shown in FIG. Figure 4 As shown. Figure 4It can be seen that when the amount of bio-based polyester polyol is 8 parts by weight, the tensile strength and elongation at break of the prepared bio-based polyurethane material are 11.3MPa and 469.9%, respectively, which are 28.4% and 37.5% higher than those of the bio-based polyurethane material prepared with 6 parts by weight of bio-based polyester polyol. In addition, with the increase in the amount of bio-based polyester polyol, the tensile strength of the bio-based polyurethane material gradually increases. When the amount of bio-based polyester polyol exceeds 6 parts by weight, the elongation at break increases significantly; when the amount of bio-based polyester polyol exceeds 8 parts by weight, the elongation at break remains basically unchanged. The thermal stability performance diagram of the bio-based polyurethane material of this embodiment is shown in the figure below. Figure 5 As shown. Figure 5 It can be seen that as the amount of bio-based polyester polyol increases, the heat resistance of the bio-based polyurethane material gradually improves. When the amount of bio-based polyester polyol is 8 parts by weight, the polyurethane material exhibits good thermal stability.

[0069] Example 3

[0070] (1) Waste PET bottle flakes and ethylene glycol are mixed in a mass ratio of 1:3 and 2 wt% of a catalyst zinc acetate (2% of the mass of the waste PET) are added to a reaction container, stirred and reacted at 190° C. for 4 h, and the product is filtered, rotary evaporated, cooled and crystallized, centrifuged and washed, and vacuum dried to obtain a depolymerized monomer bis(2-hydroxyethyl) terephthalate (BHET).

[0071] (2) According to the alcohol-acid molar ratio of 1.5:1, 5.35 parts by weight of bis(2-hydroxyethyl) terephthalate (BHET) was dissolved in 16 parts by weight of N,N-dimethylformamide, and added to the reactor, and then 8 parts by weight of bio-based hydrogenated dimer acid (HDA) and 0.16 parts by weight of catalyst p-toluenesulfonic acid were added, and stirred at 160°C and 150 rpm for 6 hours, the product was dissolved in chloroform, and then the mixture was dropped into methanol and stirred until the bio-based polyester polyol was completely precipitated, and finally filtered and dried to obtain the purified bio-based polyester polyol.

[0072] (3) In the reactor, add 10 parts by weight of the purified bio-based polyester polyol obtained in step (2), 4 parts by weight of hexamethylene diisocyanate, and 1 part by weight of chain extender BHET, first stir at 70°C at a speed of 100 rpm for 30 min, then add 0.2 parts by weight of catalyst dibutyltin dilaurate (2 wt% of the weight of the bio-based polyester polyol), stir and react for 2 hours to obtain a bio-based polyurethane prepolymer for later use.

[0073] (4) 0.25 parts by weight of an internal crosslinking agent, trimethylolpropane, was added to the polyurethane prepolymer in step (3), and the mixture was stirred at 60° C. and 150 rpm for 2 h. During the reaction, 4 parts by weight of butanone was added for dilution to obtain a bio-based polyurethane emulsion.

[0074] (5) The prepared emulsion is evenly spread on a dry and clean mold to form a liquid layer with uniform thickness and smooth surface, and then dried in an oven at 80°C for 10 hours. The bio-based polyurethane film is obtained by peeling off the film.

[0075] The preparation flow chart of the bio-based polyester polyol in this embodiment is as follows Figure 1 As shown. Figure 1 It can be seen that the carboxyl group of HDA and the hydroxyl group of BHET can undergo polycondensation reaction to polymerize into bio-based polyester polyol. The molecular weight distribution diagram of the bio-based polyester polyol of this embodiment is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that when the alkyd ratio of BHET to HDA ​​is 1.5:1, the molecular weight distribution of the prepared bio-based polyester polyol is uniform and narrow, with an average molecular weight of 2063 g / mol. The preparation flow chart of the bio-based polyurethane material of this embodiment is as follows: Figure 3 As shown. Figure 3 It can be seen that the long straight-chain polyurethane prepolymer was first synthesized using bio-based polyester polyol, hexamethylene diisocyanate, and chain extender BHET, and then the internal cross-linking agent trimethylolpropane was added to prepare a bio-based polyurethane material with a cross-linked network structure. The mechanical properties of the bio-based polyurethane material of this embodiment are shown in FIG. Figure 4 As shown. Figure 4 It can be seen that when the amount of bio-based polyester polyol is 10 parts by weight, the tensile strength and elongation at break of the prepared bio-based polyurethane material are 14.6MPa and 464.6%, respectively, which are 65.9% and 35.9% higher than those of the bio-based polyurethane material prepared with 6 parts by weight of bio-based polyester polyol. In addition, with the increase in the amount of bio-based polyester polyol, the tensile strength of the bio-based polyurethane material gradually increases. When the amount of bio-based polyester polyol exceeds 6 parts by weight, the elongation at break increases significantly; when the amount of bio-based polyester polyol exceeds 8 parts by weight, the elongation at break remains basically unchanged and remains at a relatively high level. The thermal stability performance diagram of the bio-based polyurethane material of this embodiment is shown in the figure below. Figure 5 As shown. Figure 5 It can be seen that as the amount of bio-based polyester polyol increases, the heat resistance of the bio-based polyurethane material gradually improves. When the amount of bio-based polyester polyol is 10 parts by weight, the polyurethane material exhibits excellent thermal stability.

[0076] Example 4

[0077] (1) Waste PET bottle flakes and ethylene glycol are mixed in a mass ratio of 1:3 and 2 wt% of a catalyst zinc acetate (2% of the mass of the waste PET) are added to a reaction container, stirred and reacted at 190° C. for 4 h, and the product is filtered, rotary evaporated, cooled and crystallized, centrifuged and washed, and vacuum dried to obtain a depolymerized monomer bis(2-hydroxyethyl) terephthalate (BHET).

[0078] (2) According to the alcohol-acid molar ratio of 1.5:1, 5.35 parts by weight of bis(2-hydroxyethyl) terephthalate (BHET) was dissolved in 16 parts by weight of N,N-dimethylformamide, and added to the reactor, and then 8 parts by weight of bio-based hydrogenated dimer acid (HDA) and 0.16 parts by weight of catalyst p-toluenesulfonic acid were added, and stirred at 160°C and 150 rpm for 6 hours, the product was dissolved in chloroform, and then the mixture was dropped into methanol and stirred until the bio-based polyester polyol was completely precipitated, and finally filtered and dried to obtain the purified bio-based polyester polyol.

[0079] (3) In the reactor, add 12 parts by weight of the purified bio-based polyester polyol obtained in step (2), 4 parts by weight of hexamethylene diisocyanate, and 1 part by weight of chain extender BHET, first stir at 70°C at a speed of 100 rpm for 30 min, then add 0.24 parts by weight of catalyst dibutyltin dilaurate (2 wt% of the weight of the bio-based polyester polyol), stir and react for 2 hours to obtain a bio-based polyurethane prepolymer for later use.

[0080] (4) 0.25 parts by weight of an internal crosslinking agent, trimethylolpropane, was added to the polyurethane prepolymer in step (3), and the mixture was stirred at 60° C. and 150 rpm for 2 h. During the reaction, 4 parts by weight of butanone was added for dilution to obtain a bio-based polyurethane emulsion.

[0081] (5) The prepared emulsion is evenly spread on a dry and clean mold to form a liquid layer with uniform thickness and smooth surface, and then dried in an oven at 80°C for 10 hours. The bio-based polyurethane film is obtained by peeling off the film.

[0082] The preparation flow chart of the bio-based polyester polyol in this embodiment is as follows Figure 1 As shown. Figure 1 It can be seen that the carboxyl group of HDA and the hydroxyl group of BHET can undergo polycondensation reaction to polymerize into bio-based polyester polyol. The molecular weight distribution diagram of the bio-based polyester polyol of this embodiment is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that when the alcohol-acid ratio of BHET to HAD is 1.5:1, the molecular weight distribution of the prepared bio-based polyester polyol is uniform and narrow, and the average molecular weight is 2063 g / mol. The preparation flow chart of the bio-based polyurethane material of this embodiment is as follows: Figure 3As shown. Figure 3 It can be seen that the long straight-chain polyurethane prepolymer was first synthesized using bio-based polyester polyol, hexamethylene diisocyanate, and chain extender BHET, and then the internal cross-linking agent trimethylolpropane was added to prepare a bio-based polyurethane material with a cross-linked network structure. The mechanical properties of the bio-based polyurethane material of this embodiment are shown in FIG. Figure 4 As shown. Figure 4 It can be seen that when the amount of bio-based polyester polyol is 12 parts by weight, the tensile strength and elongation at break of the prepared bio-based polyurethane material are the largest, which are 19.9MPa and 474.3%, respectively, which are 126.1% and 38.8% higher than the bio-based polyurethane material prepared with 6 parts by weight of bio-based polyester polyol. In addition, when the amount of bio-based polyester polyol exceeds 6 parts by weight, the elongation at break increases significantly; when the amount of bio-based polyester polyol exceeds 8 parts by weight, the elongation at break remains basically unchanged and remains at a relatively high level. The thermal stability performance diagram of the bio-based polyurethane material of this embodiment is shown in the figure below. Figure 5 As shown. Figure 5 It can be seen that as the amount of bio-based polyester polyol increases, the heat resistance of the bio-based polyurethane material gradually improves. When the amount of bio-based polyester polyol is 12 parts by weight, the polyurethane material exhibits the best thermal stability.

[0083] Example 5

[0084] (1) Waste PET bottle flakes and ethylene glycol are mixed in a mass ratio of 1:3 and 2 wt% of a catalyst zinc acetate (2% of the mass of the waste PET) are added to a reaction container, stirred and reacted at 190° C. for 4 h, and the product is filtered, rotary evaporated, cooled and crystallized, centrifuged and washed, and vacuum dried to obtain a depolymerized monomer bis(2-hydroxyethyl) terephthalate (BHET).

[0085] (2) According to the alcohol-acid molar ratio of 1.5:1, 5.35 parts by weight of bis(2-hydroxyethyl) terephthalate (BHET) was dissolved in 16 parts by weight of N,N-dimethylformamide, and added to the reactor, and then 8 parts by weight of bio-based hydrogenated dimer acid (HDA) and 0.16 parts by weight of catalyst p-toluenesulfonic acid were added, and stirred at 160°C and 150 rpm for 6 hours, the product was dissolved in chloroform, and then the mixture was dropped into methanol and stirred until the bio-based polyester polyol was completely precipitated, and finally filtered and dried to obtain the purified bio-based polyester polyol.

[0086] (3) In the reactor, add 6 parts by weight of the purified bio-based polyester polyol obtained in step (2), 4 parts by weight of dicyclohexylmethane diisocyanate, and 1 part by weight of chain extender BHET, first stir at 70°C at a speed of 100 rpm for 30 min, then add 0.12 parts by weight of catalyst dibutyltin dilaurate (2 wt% of the weight of the bio-based polyester polyol), stir and react for 2 hours to obtain a bio-based polyurethane prepolymer for later use.

[0087] (4) 0.25 parts by weight of an internal crosslinking agent, trimethylolpropane, was added to the polyurethane prepolymer in step (3), and the mixture was stirred at 60° C. and 150 rpm for 2 h. During the reaction, 4 parts by weight of butanone was added for dilution to obtain a bio-based polyurethane emulsion.

[0088] (5) The prepared emulsion is evenly spread on a dry and clean mold to form a liquid layer with uniform thickness and smooth surface, and then dried in an oven at 80°C for 10 hours. The bio-based polyurethane film is obtained by peeling off the film.

[0089] Example 6

[0090] (1) Waste PET bottle flakes and ethylene glycol are mixed in a mass ratio of 1:3 and 2 wt% of a catalyst zinc acetate (2% of the mass of the waste PET) are added to a reaction container, stirred and reacted at 190° C. for 4 h, and the product is filtered, rotary evaporated, cooled and crystallized, centrifuged and washed, and vacuum dried to obtain a depolymerized monomer bis(2-hydroxyethyl) terephthalate (BHET).

[0091] (2) According to the alcohol-acid molar ratio of 1.5:1, 5.35 parts by weight of bis(2-hydroxyethyl) terephthalate (BHET) were dissolved in 16 parts by weight of N,N-dimethylformamide and added to the reactor, and then 8 parts by weight of bio-based dimer acid (DA) and 0.16 parts by weight of catalyst p-toluenesulfonic acid were added. The mixture was stirred at 150 rpm for 6 hours at 160°C, and the product was dissolved in chloroform. The mixture was then dropped into methanol and stirred until the bio-based polyester polyol was completely precipitated. Finally, it was filtered and dried to obtain the purified bio-based polyester polyol.

[0092] (3) In the reactor, add 6 parts by weight of the purified bio-based polyester polyol obtained in step (2), 4 parts by weight of hexamethylene diisocyanate, and 1 part by weight of chain extender BHET, first stir at 70°C at a speed of 100 rpm for 30 min, then add 0.12 parts by weight of catalyst dibutyltin dilaurate (2 wt% of the weight of the bio-based polyester polyol), stir and react for 2 hours to obtain a bio-based polyurethane prepolymer for later use.

[0093] (4) 0.25 parts by weight of an internal crosslinking agent, trimethylolpropane, was added to the polyurethane prepolymer in step (3), and the mixture was stirred at 60° C. and 150 rpm for 2 h. During the reaction, 4 parts by weight of butanone was added for dilution to obtain a bio-based polyurethane emulsion.

[0094] (5) The prepared emulsion is evenly spread on a dry and clean mold to form a liquid layer with uniform thickness and smooth surface, and then dried in an oven at 80°C for 10 hours. The bio-based polyurethane film is obtained by peeling off the film.

Claims

1. A bio-based polyurethane material, characterized in that: It is prepared from the following raw materials in parts by weight:

2. The bio-based polyurethane material according to claim 1, characterized in that: The bis(2-hydroxyethyl) terephthalate is obtained by depolymerization of PET. The preparation method is as follows: in a protective atmosphere, PET and a depolymerizing agent react at 180-200° C. for 3-5 hours under the action of a catalyst, and then purified to obtain a depolymerization product, bis(2-hydroxyethyl) terephthalate; the depolymerizing agent is ethylene glycol.

3. The bio-based polyurethane material according to claim 2, characterized in that: The mass ratio of the PET to the depolymerizing agent is 1:(2-4); the amount of the catalyst is 1-3% of the mass of the PET; The PET is waste PET; The catalyst is one or more of zinc acetate, copper acetate, nickel acetate and manganese acetate; The purification treatment refers to filtering after the reaction, rotary evaporation, cooling crystallization, centrifugal washing, and vacuum drying to obtain the depolymerization product bis(2-hydroxyethyl) terephthalate.

4. The bio-based polyurethane material according to claim 1, characterized in that: The bio-based dimer acid is one or more of a hydrogenated dimer acid and a dimer acid; the molecular weight of the bio-based dimer acid is 400-600.

5. The bio-based polyurethane material according to claim 1, characterized in that: The diisocyanate is one or more of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and toluene diisocyanate; The chain extender is one or more of bis(2-hydroxyethyl) terephthalate, 1,4-butanediol, ethylene glycol, propylene glycol, neopentyl glycol, ethanolamine, diethanolamine, and triethanolamine; The internal cross-linking agent is one or more of trimethylolpropane, propylene glycol, glycerol and pentaerythritol.

6. The bio-based polyurethane material according to claim 1, characterized in that: The catalyst is one or more of tetrabutyl titanate, p-toluenesulfonic acid, dibutyltin dilaurate, dibutyltin diacetate, and stannous octoate; the organic solvent is one or more of N,N-dimethylformamide, N-methylpyrrolidone, and butanone; and the diluent is one or more of butanone, acetone, N,N-dimethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

7. The method for preparing a bio-based polyurethane material according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) dissolving bis(2-hydroxyethyl) terephthalate in an organic solvent, mixing with bio-based dimer acid, adding a catalyst, reacting at 150-170° C. for 4-8 hours; and subsequently treating to obtain bio-based polyester polyol; 2) mixing the bio-based polyol with diisocyanate and chain extender, adding a catalyst, and reacting at 60-80° C. to obtain a bio-based polyurethane prepolymer; the mixing refers to stirring at 60-80° C. for 20-40 minutes, and the reaction time is 1 to 3 hours; 3) mixing the bio-based polyurethane prepolymer with the internal cross-linking agent, stirring and reacting at 50-70° C. for 1-3 hours, and adding a diluent to dilute the reaction to obtain a bio-based polyurethane emulsion; 4) Forming a film of the bio-based polyurethane emulsion to obtain a bio-based polyurethane material.

8. The preparation method according to claim 7, characterized in that: Step 1) is to dissolve bis(2-hydroxyethyl) terephthalate in an organic solvent, mix it with bio-based dimer acid in an alcohol-acid molar ratio of 1.5:1, add a catalyst, and react at 150-170° C. for 4-8 hours; and subsequently treat to obtain bio-based polyester polyol; The organic solvent in step 1) is one or more of N,N-dimethylformamide, N-methylpyrrolidone and butanone; The weight ratio of the organic solvent to BHET in step 1) is (12-18): (4-6); The catalyst in step 1) is one or more of tetrabutyl titanate, p-toluenesulfonic acid, dibutyltin dilaurate, and dibutyltin diacetate; the amount of the catalyst is 1-3% of the mass of the bio-based dimer acid; The subsequent treatment described in step 1) refers to dissolving in chloroform after the reaction is completed and precipitating in methanol to obtain purified bio-based polyester polyol; The stirring speed in step 2) is 50 to 150 rpm; The stirring speed in step 3) is 100-200 rpm.

9. The method for preparing bio-based polyurethane according to claim 8, characterized in that: In the preparation of bio-based polyester polyols, the subsequent treatment refers to dissolving in chloroform and precipitating in methanol after the reaction is completed.

10. The use of the bio-based polyurethane material according to any one of claims 1 to 6, characterized in that: The bio-based polyurethane material is used in the fields of biomedical materials, food packaging materials, and biodegradable ground film materials.

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