Process for the synthesis of branched polyesters from polyesters and carbon dioxide derivatives and products thereof

Abstract

The application discloses a method for synthesizing branched polyester by using polyester and carbon dioxide derivatives and a product thereof. The method comprises the following steps: performing solid-phase ester exchange reaction on the carbon dioxide derivatives and the polyester under the conditions of inert gas protection and heating to obtain branched polyester; and the carbon dioxide derivatives comprise at least one of 3-ethylidene-6-vinyl tetrahydro-2H-pyran-2-one and a homopolymer pEVL thereof. The application can utilize a large amount of polyester materials and carbon dioxide waste to solve the current more intractable carbon emission and pollution problems.

Description

Technical Field

[0001] This invention relates to the field of polymer material synthesis technology and recycling, specifically to a method for synthesizing branched polyester using polyester and carbon dioxide derivatives, the product thereof, and the application of this method in polyester recycling. Background Technology

[0002] Post-processing of plastic waste and reduction of carbon dioxide emissions are both key issues in the field of environmental protection.

[0003] Polyester is one of the world's most popular plastics, and large amounts of polyester waste are discarded and accumulate in the environment, becoming a major source of pollution. Carbon dioxide, an abundant C1 resource, is generally considered a worthless waste and is also one of the main culprits of the greenhouse effect. Existing treatment methods, such as plastic incineration or degradation and carbon dioxide hydrogenation, are far from perfect. Therefore, developing technologies for the co-recycling and utilization of polyester and carbon dioxide is not only highly attractive as it can effectively reduce carbon emissions and alleviate pollution problems.

[0004] Currently, various 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 its preparation method, which is obtained by one-pot one-step polymerization of epoxy monomers, phthalic anhydride, and carbon dioxide in the presence of a bifunctional organoboron catalyst and a chain transfer agent containing two active hydrogens.

[0005] In addition, existing technology describes a unique and successful method for converting carbon dioxide into polymers, which involves first synthesizing a polymerization intermediate, 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVL), from carbon dioxide and 1,3-butadiene via a telomerization reaction, and then homopolymerizing it through ring-opening polymerization to obtain pEVL (B. Grignard, S. Genennen, C.). (AWKleij, C. Detrembleur, Chem. Soc. Rev. 2019, 48, 4466-4514; A. Behr, G. Henze, GreenChem. 2011, 13, 25-39; K. Nozaki, Bull. Chem. Soc. Jpn. 2021, 94, 984-988). Through this route, carbon dioxide is cured to form carbon dioxide derivatives and even polymers. However, the lack of clear applications for these carbon dioxide derivatives limits their large-scale utilization.

[0006] Therefore, this invention utilizes a large amount of polyester material and carbon dioxide waste to obtain branched polyester products through a one-step reaction. By controlling the reaction temperature, the product of this 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] To address the aforementioned technical problems and shortcomings in this field, the present invention provides a method for synthesizing branched polyesters using polyester and carbon dioxide derivatives, along with the resulting products, and the application of this method in polyester recycling. This invention can utilize large quantities of polyester materials and carbon dioxide waste to solve the currently challenging problems of carbon emissions and pollution.

[0008] This invention directly reacts polyester with carbon dioxide derivatives in a solid-state environment, utilizing the ester bonds in the polyester and carbon dioxide derivatives to undergo a dynamic transesterification reaction in one step to obtain branched polyester. This invention creatively utilizes the reaction between polymers, enabling the rapid preparation of branched polyester products. The polyester used in this invention can be commercially available polyester, waste polyester products, etc., thus significantly reducing carbon emissions in polyester recycling.

[0009] The specific technical solution is 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 carbon dioxide derivatives and polyester to a solid-phase transesterification reaction under inert gas protection and heating conditions to obtain branched polyester.

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

[0012] The principle of this invention is to utilize the dynamic generation and destruction of ester bonds in polyesters and carbon dioxide derivatives to prepare branched polyesters through cross-ester exchange reactions between solid-phase monomers and polymer chains.

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

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

[0015] The inert gas mentioned in the method of this invention refers to a gas that will not participate in the reaction, such as rare gases like argon.

[0016] In some embodiments, in the method for synthesizing branched polyesters using polyesters and carbon dioxide derivatives as described in the first aspect, the number-average molecular weight of the homopolymer pEVL can be 300 to 30000 g / mol, for example, 1 kDa, 3 kDa, 5 kDa, 10 kDa, etc.

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

[0018]

[0019] Where n and x are independent positive integers.

[0020] The polyester used in the method of the present invention is not particularly limited. In some embodiments, the method for synthesizing branched polyesters using polyesters and carbon dioxide derivatives as described in the first aspect may include at least one of polyethylene terephthalate, polyethylene terephthalate, polyethylene butylene terephthalate, polyethylene pentylene terephthalate, polyethylene furanyl ester, polyethylene succinate, polyethylene butylene succinate, polyethylene adipate, polyethylene adipate, polyethylene terephthalate, polyethylene adipate, polyethylene butylene terephthalate, polyethylene adipate, polyethylene furanyl ester, etc.

[0021] In some embodiments, the method for synthesizing branched polyesters using polyesters and carbon dioxide derivatives as described in the first aspect, wherein the transesterification reaction is carried out without the addition of a catalyst.

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

[0023] In some preferred embodiments, in the method for synthesizing branched polyesters using polyester and carbon dioxide derivatives as described in the first aspect, the transesterification reaction temperature can be 150–230°C, for example, 150°C, 200°C, etc.; the reaction pressure can be 80–300 kPa, for example, atmospheric pressure, 300 kPa, etc.; and the reaction time can be 1–8 h, for example, 1 h, 3 h, 8 h, etc. Within the above preferred reaction temperature range, the resulting 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. Further increasing the reaction temperature will cause the resulting branched polyester to crosslink, making it unsuitable for blow molding or foaming processing.

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

[0025] In some embodiments, the number-average molecular weight of the branched polyester may be 22 to 40 kDa, such as 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 can be 39 to 124 kDa, such as 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 application of the method for synthesizing branched polyesters using polyesters and carbon dioxide derivatives as described in the first aspect in the recycling of polyesters.

[0028] Compared with the prior art, the beneficial effects of this invention are as follows:

[0029] 1) This invention can convert high molecular weight polyester into branched polyester in one step without the need for a first degradation into monomers, which significantly reduces costs.

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

[0031] 3) This invention uses a solid-phase reaction, which lowers the reaction temperature. On the one hand, this can prevent the decomposition of reactants, and on the other hand, it can reduce the energy consumption of the reaction. Attached Figure Description

[0032] Figure 1 The hydrogen nuclear magnetic resonance (NMR) of the branched polyester product prepared in Example 1. 1 H NMR spectrum. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0035] Unless otherwise specified, the pEVL used in the following examples all have the chemical structures shown below:

[0036]

[0037] Where n and x are independent 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 a solid-phase reactor. A solid-phase reaction was carried out under atmospheric pressure at 200 °C for 3 hours under an Ar gas flow. After the reaction was completed, the branched polyester product was tested and found to have a number average molecular weight of 32 kDa and a weight average molecular weight of 81 kDa.

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

[0041] Examples 2-4

[0042] The synthesis process is the same as in 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 Examples 2, 3 and 4.

[0043] Tests showed that the branched polyester product obtained in Example 2 had a number-average molecular weight of 40 kDa and a weight-average molecular weight of 77 kDa.

[0044] The branched polyester product obtained in Example 3 has a number-average molecular weight of 35 kDa and a weight-average molecular weight of 79 kDa.

[0045] The branched polyester product obtained in Example 4 had a number-average molecular weight of 29 kDa and a weight-average molecular weight of 88 kDa.

[0046] Examples 5 and 6

[0047] The synthesis process is the same as in Example 1, except that the reaction temperature is changed to 150℃ and 250℃ respectively, corresponding to Example 5 and Example 6.

[0048] Tests showed that the branched polyester product obtained in Example 5 had a number-average molecular weight of 25 kDa and a weight-average molecular weight of 59 kDa.

[0049] Tests showed that the crosslinked branched polyester product obtained in Example 6 was insoluble in hexafluoroisopropanol.

[0050] Example 6: The cross-linked branched polyester product is difficult to process.

[0051] Examples 7 and 8

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

[0053] Tests showed that the branched polyester product obtained in Example 7 had a number-average molecular weight of 26 kDa and a weight-average molecular weight of 61 kDa.

[0054] Tests showed that the branched polyester product obtained in Example 8 had a number-average molecular weight of 38 kDa and a weight-average molecular weight of 124 kDa.

[0055] Examples 9-11

[0056] The synthesis process is the same as in Example 1, except 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), corresponding to Examples 9, 10, and 11, respectively.

[0057] Tests showed that the branched polyester product obtained in Example 9 had a number-average molecular weight of 34 kDa and a weight-average molecular weight of 78 kDa.

[0058] The branched polyester product obtained in Example 10 had a number-average molecular weight of 32 kDa and a weight-average molecular weight of 80 kDa.

[0059] The branched polyester product obtained in Example 11 has a number-average molecular weight of 30 kDa and a weight-average molecular weight of 87 kDa.

[0060] Example 12

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

[0062] The branched polyester product obtained in Example 12 had a number-average molecular weight of 22 kDa and a weight-average molecular weight of 39 kDa.

[0063] Examples 13-14

[0064] The synthesis process is the same as in Example 1, except that polyethylene terephthalate is replaced with equal masses of polyethylene terephthalate and polyethylene furanate, respectively, corresponding to Examples 13 and 14.

[0065] Tests showed that the branched polyester product obtained in Example 13 had a number-average molecular weight of 33 kDa and a weight-average molecular weight of 90 kDa.

[0066] The branched polyester product obtained in Example 14 had a number-average molecular weight of 28 kDa and a weight-average molecular weight of 70 kDa.

[0067] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for synthesizing branched polyesters using polyester and carbon dioxide derivatives, characterized in that, This includes: carrying out a solid-phase transesterification reaction between carbon dioxide derivatives and polyester under inert gas protection and heating conditions to obtain branched polyester; The carbon dioxide derivatives include the homopolymer pEVL of 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one; The number-average molecular weight of the homopolymer pEVL is 300~30000 g / mol; The homopolymer pEVL has the following chemical structure: Where n and x are independent positive integers.

2. The method according to claim 1, characterized in that, The polyester comprises at least one of polyethylene terephthalate, polyethylene terephthalate, polyethylene butylene terephthalate, polyethylene pentylene terephthalate, polyethylene furanyl dicarboxylate, polyethylene succinate, polyethylene butylene succinate, polyethylene adipate, polyethylene adipate, polyethylene terephthalate succinate, polyethylene adipate succinate, polyethylene adipate succinate, polyethylene adipate succinate, polyethylene adipate succinate, and polyethylene furanyl dicarboxylate.

3. The method according to claim 1, characterized in that, The transesterification reaction was carried out without the addition of a catalyst.

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

5. The method according to claim 1, characterized in that, The transesterification reaction is carried out at a temperature of 150-230℃, a pressure of 80-300 kPa, and a time of 1-8 h.

6. The method according to claim 1, characterized in that, The branched polyester has a number-average molecular weight of 22-40 kDa and a weight-average molecular weight of 39-124 kDa.

7. The application of the method according to any one of claims 1 to 6 in the recycling of polyester.

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