Method for synthesizing branched polyester by using polyester and carbon dioxide derivative and product thereof

Abstract

The invention discloses a method for synthesizing branched polyester by using polyester and a carbon dioxide derivative and a product thereof. The method comprises the following steps: carrying out solid-phase ester exchange reaction on a carbon dioxide derivative and polyester under inert gas protection and heating conditions to obtain branched polyester; the carbon dioxide derivative is prepared from at least one of 3-ethylidene-6-vinyl tetrahydro-2H-pyran-2-ketone and a homopolymer pEVL (Poly (Ethylene Vinyl Vinyl) L) thereof. According to the invention, a large amount of polyester materials and carbon dioxide wastes can be utilized, so that the current relatively difficult problems of carbon emission and pollution are solved.

Description

Technical Field

[0001] The invention relates to the field of polymer material synthesis technology and recycling, and in particular to a method for synthesizing branched polyester using polyester and carbon dioxide derivatives and its product, as well as application of the method in recycling polyester. Background Art

[0002] Plastic waste reprocessing and reducing carbon dioxide emissions are both key issues in the field of environmental protection.

[0003] Polyester is one of the most popular plastics in the world. A large amount of polyester waste is discarded and accumulates in the environment, becoming one of the main sources of pollution. Carbon dioxide is an abundant C1 resource, which is generally considered a worthless waste and one of the culprits of the enhanced greenhouse effect. Existing treatment methods, such as incineration or degradation of plastics and hydrogenation of carbon dioxide, are far from perfect. Therefore, the development of synergistic recycling technology of polyester and carbon dioxide can not only effectively reduce carbon emissions, but also alleviate pollution problems, which is of great appeal.

[0004] At present, a variety of methods for converting carbon dioxide into polymers have been developed. For example, the patent specification with publication number CN116003759A discloses a carbon dioxide-based polyester polycarbonate diol and a preparation method thereof, which is obtained by polymerizing epoxy monomer, phthalic anhydride and carbon dioxide in one pot in the presence of a bifunctional organic boron catalyst and a chain transfer agent containing two active hydrogens.

[0005] In addition, the prior art introduces a unique and successful method for converting carbon dioxide into a polymer, which is to first synthesize the polymerization intermediate 3-ethylene-6-vinyltetrahydro-2H-pyran-2-one (EVL) by telomerization of carbon dioxide and 1,3-butadiene, and then homopolymerize it by ring-opening polymerization to obtain pEVL (B.Grignard, S.Gennen, C. AW Kleij, C. Detrembleur, Chem. Soc. Rev. 2019, 48, 4466-4514; A. Behr, G. Henze, Green Chem. 2011, 13, 25-39; K. Nozaki, Bull. Chem. Soc. Jpn. 2021, 94, 984-988). Through this approach, carbon dioxide is solidified to form carbon dioxide derivatives or even polymers. However, these carbon dioxide derivatives have no clear uses, which limits their large-scale use.

[0006] To this end, the present invention utilizes a large amount of polyester material and carbon dioxide waste to obtain a branched polyester product in a one-step reaction. By adjusting the reaction temperature, the product of the present invention can have a higher melt strength than the original polyester, which can significantly improve the processing performance of the original polyester and facilitate blow molding or foaming processing. Summary of the invention

[0007] In view of the above technical problems and the shortcomings in the art, the present invention provides a method for synthesizing branched polyester using polyester and carbon dioxide derivatives and its products, as well as the application of the method in recycling polyester. The present invention can utilize a large amount of polyester materials and carbon dioxide waste to solve the current more difficult carbon emission and pollution problems.

[0008] The present invention directly reacts polyester with carbon dioxide derivatives in a solid phase, and uses the ester bonds in the polyester and the carbon dioxide derivatives to perform a dynamic transesterification reaction to obtain branched polyester in one step. The present invention creatively uses the reaction between polymers so that the branched polyester product can be quickly prepared. The polyester in the present invention can be commercial polyester, waste polyester products, etc., so the present invention can significantly reduce carbon emissions in polyester recycling.

[0009] The specific technical solutions are as follows:

[0010] In a first aspect, the present invention provides a method for synthesizing branched polyester using polyester and carbon dioxide derivatives, comprising: subjecting the carbon dioxide derivative and the polyester to a solid phase transesterification reaction under inert gas protection and heating conditions to obtain the branched polyester;

[0011] The carbon dioxide derivative includes at least one of 3-ethylene-6-vinyltetrahydro-2H-pyran-2-one (EVL) and its homopolymer pEVL.

[0012] The principle of the present invention is to utilize the characteristics that the ester bonds in polyester and carbon dioxide derivatives can be dynamically generated and eliminated, and to prepare branched polyester through cross-esterification reaction between solid-phase monomers and polymer chains.

[0013] In some embodiments, in the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect, the polyester and the carbon dioxide derivative may both be in the form of powder.

[0014] In some embodiments, the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect can use carbon dioxide derivatives and polyester as raw materials only, and conduct solid phase transesterification reaction under inert gas protection and heating conditions to obtain branched polyester.

[0015] The inert gas described in the method of the present invention refers to a gas that does not participate in the reaction, such as rare gases such as argon.

[0016] In some embodiments, in the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect, the number average molecular weight of the homopolymer pEVL can be 300 to 30,000 g / mol, for example, 1 kDa, 3 kDa, 5 kDa, 10 kDa, etc.

[0017] In some embodiments, in the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect, the homopolymer pEVL may have the following chemical structure:

[0018]

[0019] Wherein, n and x are independently positive integers.

[0020] The polyester used in the method of the present invention may not be particularly limited. In some embodiments, in the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect, the polyester may include at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polypentylene terephthalate, polyethylene furandicarboxylate, polyethylene succinate, polybutylene succinate, polyethylene adipate, polybutylene adipate, polyethylene terephthalate succinate, polyethylene terephthalate adipate, polybutylene terephthalate succinate, polybutylene terephthalate adipate, polybutylene succinate adipate, polybutylene succinate adipate, polyethylene furandicarboxylate, etc.

[0021] In some embodiments, in the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect, the transesterification reaction does not require any additional catalyst.

[0022] In some embodiments, in the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect, the mass ratio of the polyester to the carbon dioxide derivative can be 100:(1-50), for example, 100:2, 100:6, 100:10, 100:20, etc.

[0023] In some preferred examples, in the method for synthesizing branched polyester using polyester and carbon dioxide derivatives described in the first aspect, the reaction temperature of the transesterification reaction can be 150-230°C, such as 150°C, 200°C, etc., the reaction pressure can be 80-300kPa, such as normal pressure, 300kPa, etc., and the reaction time can be 1-8h, such as 1h, 3h, 8h, etc. In the above preferred reaction temperature range, the obtained branched polyester has a higher melt strength than the original polyester, which can significantly improve the processing performance of the original polyester and facilitate blow molding or foaming processing. If the reaction temperature is further increased, the obtained branched polyester will be cross-linked and is not suitable for the field of blow molding or foaming processing.

[0024] In a second aspect, the present invention provides a branched polyester synthesized by the method for synthesizing a branched polyester using polyester and a carbon dioxide derivative as described in the first aspect.

[0025] In some embodiments, the number average molecular weight of the branched polyester may be 22 to 40 kDa, for example, 22 kDa, 25 kDa, 26 kDa, 28 kDa, 29 kDa, 30 kDa, 32 kDa, 33 kDa, 34 kDa, 35 kDa, 38 kDa, 40 kDa, etc.

[0026] In some embodiments, the weight average molecular weight of the branched polyester may be 39 to 124 kDa, for example, 39 kDa, 59 kDa, 61 kDa, 70 kDa, 77 kDa, 78 kDa, 79 kDa, 80 kDa, 81 kDa, 87 kDa, 88 kDa, 90 kDa, 124 kDa, etc.

[0027] As a general inventive concept, in a third aspect, the present invention provides the use of the method for synthesizing branched polyester using polyester and carbon dioxide derivatives as described in the first aspect in recycling polyester.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) The present invention can convert high molecular weight polyester into branched polyester in one step without the need for a step of first degrading it into monomers, thus significantly reducing the cost.

[0030] 2) The present invention uses carbon dioxide-based derivatives to significantly reduce carbon emissions, and the polyester used can be a recycled waste product, so this synthesis route is an environmentally friendly process.

[0031] 3) The present invention adopts solid phase reaction, which reduces the reaction temperature, can prevent the decomposition of reactants on the one hand, and also reduces the reaction energy consumption on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the hydrogen nuclear magnetic resonance (HNMR) of the branched polyester product prepared in Example 1 1 H NMR) spectrum. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0034] The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or conditions recommended by the manufacturers.

[0035] Unless otherwise specified, the pEVL used in the following examples has the following chemical structure:

[0036]

[0037] Wherein, n and x are independently positive integers.

[0038] Example 1

[0039] 5.00 g of polyethylene terephthalate powder and 0.50 g of pEVL powder (number average molecular weight 3.0 kDa) were added to the solid phase reactor, and a solid phase reaction was carried out at normal pressure under Ar gas flow, at a reaction temperature of 200°C, and for 3 hours. After the reaction was completed, the number average molecular weight of the branched polyester product was tested to be 32 kDa and the weight average molecular weight was 81 kDa.

[0040] Figure 1 The branched polyester product prepared in this example is given. 1 H NMR spectra.

[0041] Embodiments 2 to 4

[0042] The synthesis process is the same as that of Example 1, except that the mass of pEVL powder (number average molecular weight 3.0 kDa) in the feed is changed to 0.10 g, 0.30 g and 1.00 g, respectively, corresponding to Example 2, Example 3 and Example 4.

[0043] After testing, the number average molecular weight of the branched polyester product obtained in Example 2 was 40 kDa, and the weight average molecular weight was 77 kDa.

[0044] The number average molecular weight of the branched polyester product obtained in Example 3 is 35 kDa, and the weight average molecular weight is 79 kDa.

[0045] The number average molecular weight of the branched polyester product obtained in Example 4 is 29 kDa, and the weight average molecular weight is 88 kDa.

[0046] Embodiment 5, 6

[0047] The synthesis process is the same as that of Example 1, except that the reaction temperature is changed to 150° C. and 250° C., which correspond to Example 5 and Example 6, respectively.

[0048] After testing, the number average molecular weight of the branched polyester product obtained in Example 5 was 25 kDa, and the weight average molecular weight was 59 kDa.

[0049] After testing, it was found that the branched polyester product obtained in Example 6 was cross-linked and could not be dissolved in hexafluoroisopropanol.

[0050] The processing of the cross-linked branched polyester product of Example 6 is relatively difficult.

[0051] Embodiment 7, 8

[0052] The synthesis process is the same as that of Example 1, except that the reaction time is changed to 1 hour and 8 hours, respectively, corresponding to Example 7 and Example 8.

[0053] After testing, the number average molecular weight of the branched polyester product obtained in Example 7 was 26 kDa, and the weight average molecular weight was 61 kDa.

[0054] After testing, the number average molecular weight of the branched polyester product obtained in Example 8 was 38 kDa, and the weight average molecular weight was 124 kDa.

[0055] Embodiments 9 to 11

[0056] The synthesis process is the same as that of Example 1, with the only difference being that the pEVL powder (number average molecular weight 3.0 kDa) is replaced with equal masses of pEVL powder (number average molecular weight 1.0 kDa), pEVL powder (number average molecular weight 5.0 kDa), and pEVL powder (number average molecular weight 10.0 kDa), which correspond to Example 9, Example 10, and Example 11, respectively.

[0057] After testing, the number average molecular weight of the branched polyester product obtained in Example 9 was 34 kDa, and the weight average molecular weight was 78 kDa.

[0058] The number average molecular weight of the branched polyester product obtained in Example 10 is 32 kDa, and the weight average molecular weight is 80 kDa.

[0059] The number average molecular weight of the branched polyester product obtained in Example 11 is 30 kDa, and the weight average molecular weight is 87 kDa.

[0060] Example 12

[0061] The synthesis process was the same as that of Example 1, except that the pEVL powder (number average molecular weight 3.0 kDa) was replaced with an equal mass of EVL, and the reaction pressure was changed to 300 kPa.

[0062] The number average molecular weight of the branched polyester product obtained in Example 12 is 22 kDa, and the weight average molecular weight is 39 kDa.

[0063] Embodiments 13-14

[0064] The synthesis process is the same as that of Example 1, except that polyethylene terephthalate is replaced by polybutylene terephthalate and polyethylene furandicarboxylate of equal mass, corresponding to Example 13 and Example 14, respectively.

[0065] After testing, the number average molecular weight of the branched polyester product obtained in Example 13 was 33 kDa, and the weight average molecular weight was 90 kDa.

[0066] The number average molecular weight of the branched polyester product obtained in Example 14 is 28 kDa, and the weight average molecular weight is 70 kDa.

[0067] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for synthesizing branched polyester using polyester and carbon dioxide derivatives, characterized in that: The method comprises: subjecting a carbon dioxide derivative and a polyester to a solid-phase transesterification reaction under inert gas protection and heating conditions to obtain a branched polyester; The carbon dioxide derivative includes at least one of 3-ethylene-6-vinyltetrahydro-2H-pyran-2-one and its homopolymer pEVL.

2. The method according to claim 1, characterized in that The number average molecular weight of the homopolymer pEVL is 300 to 30,000 g / mol.

3. The method according to claim 1 or 2, characterized in that: The homopolymer pEVL has the chemical structure shown below: Wherein, n and x are independently positive integers.

4. The method according to claim 1, characterized in that The polyester includes at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polypentylene terephthalate, polyethylene furandicarboxylate, polyethylene succinate, polybutylene succinate, polyethylene adipate, polybutylene adipate, polyethylene terephthalate succinate, polyethylene terephthalate adipate, polybutylene terephthalate succinate, polybutylene terephthalate adipate, polybutylene succinate adipate, and polyethylene furandicarboxylate succinate.

5. The method according to claim 1, characterized in that The transesterification reaction was carried out without adding any additional catalyst.

6. The method according to claim 1, characterized in that The mass ratio of the polyester to the carbon dioxide derivative is 100:(1-50).

7. The method according to claim 1, characterized in that The reaction temperature of the transesterification reaction is 150-230° C., the reaction pressure is 80-300 kPa, and the reaction time is 1-8 hours.

8. The branched polyester synthesized by the method according to any one of claims 1 to 7.

9. The branched polyester according to claim 8, characterized in that The number average molecular weight of the branched polyester is 22-40 kDa, and the weight average molecular weight is 39-124 kDa.

10. Use of the method according to any one of claims 1 to 7 in recycling polyester.

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