Flame-retardant functional degradation method of unsaturated polyester and application of product of flame-retardant functional degradation method

Abstract

The invention discloses a flame-retardant functional degradation method of unsaturated polyester and application of a product of the flame-retardant functional degradation method, and belongs to the technical field of upgrading and recycling of waste unsaturated polyester. According to the flame-retardant functional degradation method of the unsaturated polyester, a phosphorus-containing flame-retardant alcoholysis system is constructed to react with the unsaturated polyester, the alcoholysis reaction of the unsaturated polyester is promoted, a phosphorus-containing structure is introduced, and flame-retardant polyol with a functional degradation product is obtained. The phosphorus-containing flame-retardant alcoholysis system comprises a phosphorus-containing aromatic flame-retardant alcoholysis agent and an ionic liquid catalyst. The flame-retardant polyol is applied to synthesis of polyurethane and unsaturated polyester materials. According to the method disclosed by the invention, the dissolution and site selectivity of an alcoholysis system of the unsaturated polyester are improved, the degradation product can be endowed with specific performance, and the unsaturated polyester waste is promoted to be converted into a functionalized high-added-value product.

Description

Technical Field

[0001] This invention relates to the field of upgrading and recycling technology of waste unsaturated polyester, and in particular to a method for flame-retardant functional degradation of unsaturated polyester and the application of its products. Background Technology

[0002] Unsaturated polyester resin is one of the most widely used thermosetting materials, composed of a homogeneous mixture of unsaturated polyester condensate and styrene diluent. Due to its excellent mechanical, corrosion resistance, thermal stability, and chemical stability, it is highly favored in fields such as chemical corrosion protection, rail transportation, and building materials. In recent years, my country's annual production of unsaturated polyester resin has continued to grow, reaching 3.21 million tons in 2020; the global market size of unsaturated polyester resin is projected to grow at a CAGR of 5.49%, reaching 93.323 billion yuan in 2028. However, along with its large-scale production and use, the amount of waste and obsolete thermosetting unsaturated polyester and its composite materials is also rapidly accumulating, causing significant environmental pollution, fire hazards, and biosafety risks. In the structure of unsaturated polyester materials, the styrene-maleic anhydride copolymer segment accounts for 50-60 wt%. Therefore, the efficient degradation of unsaturated polyester and the effective recovery of styrene-maleic acid can be used as a breakthrough for its recycling, developing new methods for the efficient recycling of unsaturated polyester.

[0003] Chemical alcoholysis can degrade polyester materials to obtain alcohol products through transesterification. Commonly used alcoholysis agents include ethylene glycol, propylene glycol, diethylene glycol, and glycerol. However, these alcoholysis agents are involved in processes such as surface dissolution, swelling, and polyester chain scission of unsaturated polyesters, and have little effect on the transformation of its degradation products. Summary of the Invention

[0004] The purpose of this invention is to provide a flame-retardant functional degradation method and application for unsaturated polyester, which can improve the solubility and site selectivity of the alcoholysis system, and endow the degradation products with specific properties, thereby promoting the transformation of unsaturated polyester waste into functional high-value-added products.

[0005] To achieve the above objectives, the present invention provides a method for the flame-retardant functional degradation of unsaturated polyester. The method involves constructing a phosphorus-containing flame-retardant alcoholysis system to react with the unsaturated polyester, thereby promoting the alcoholysis reaction of the unsaturated polyester, introducing a phosphorus-containing structure, and obtaining the functional degradation product – flame-retardant polyol.

[0006] Preferably, the specific steps include: S1. Unsaturated polyester cured material is crushed into powder and passed through a 40-100 mesh sieve; S2. Add the unsaturated polyester cured powder to the phosphorus-containing flame retardant alcoholysis system and mix evenly. Place the mixture in a hydrothermal reactor and react at a temperature range of 150-210℃ for 2-10 hours to obtain the flame retardant polyol.

[0007] Preferably, the mass ratio of the unsaturated polyester cured powder to the phosphorus-containing flame-retardant alcoholysis system is 1:(1-5).

[0008] Preferably, the phosphorus-containing flame-retardant alcoholysis system includes a phosphorus-containing aromatic flame-retardant alcoholysis agent and an ionic liquid catalyst.

[0009] Preferably, the mass ratio of the phosphorus-containing aromatic flame retardant alcoholysis agent to the ionic liquid catalyst is (10-40):1.

[0010] Preferably, the phosphorus-containing aromatic flame retardant alcoholysis agent comprises one or more of the following compounds, the molecular formulas and names of which are as follows: 6-((1,3-dihydroxypropyl-2-yl)oxy)dibenzo[c,e][1,2]oxaphosphine-6-oxide, 1,3-Dihydroxypropyl-2-yldiphenylphosphine ester, 1,3-Dihydroxypropyl-2-yldiphenyl phosphate, 6-((bis(2-hydroxyethyl)amino)methyl)dibenzo[c,e][1,2]oxaphosphine-6-oxide, ((bis(2-hydroxyethyl)amino)methyl)diphenylphosphine oxide, ((bis(2-hydroxyethyl)amino)methyl)phosphonic acid diphenyl ester.

[0011] Preferably, the ionic liquid catalyst is one or more of the following ionic liquids, the chemical formulas and names of which are as follows: Formic acid choline, Acetylcholine, Choline bisulfate or Phosphocholine.

[0012] Preferably, in step S2, the mass ratio of the unsaturated polyester cured powder to the flame-retardant alcoholysis system is 1:(1-5).

[0013] The present invention also provides the application of the product of the above-mentioned flame-retardant functional degradation method of unsaturated polyester, wherein the product is a flame-retardant polyol, and the flame-retardant polyol is used in the synthesis of polyurethane and unsaturated polyester materials.

[0014] Based on the principle of like dissolves like and molecular polarity regulation, this invention synthesizes functionalized alcoholysis agents with similar solubility parameters to unsaturated polyesters. This not only improves the solubility and site selectivity of the alcoholysis system, but also endows the degradation products with specific properties, promoting the transformation of unsaturated polyester waste into functionalized high-value-added products.

[0015] Meanwhile, phosphorus-containing aromatic flame-retardant alcoholysis agents possess an aromatic structure similar to that of unsaturated polyesters, and the phosphorus-containing structure significantly enhances molecular polarity, which helps improve the surface solubility and swelling characteristics of unsaturated polyesters at high temperatures, increases the contact area between unsaturated polyesters and the alcoholysis system, and thus promotes the degradation process. Furthermore, highly efficient catalysts also contribute to improving degradation efficiency. Non-metallic ionic liquids have advantages such as high designability, low volatility, and good thermal stability, and their anions and cations have a synergistic effect on the selection of alcoholysis reaction sites, forming a highly efficient alcoholysis system together with phosphorus-containing aromatic flame-retardant alcoholysis agents.

[0016] Therefore, the present invention employs the above-mentioned flame-retardant functionalization degradation method and application of unsaturated polyester, which has the following beneficial effects: (1) The phosphorus-containing aromatic flame retardant alcoholysis agent introduces a phosphorus-containing structure, which can enhance the polarity of the alcoholysis agent and introduce the phosphorus-containing flame retardant structure into the degradation product through the alcoholysis reaction, thereby obtaining a high-value-added degradation product with flame retardant functionality.

[0017] (2) The introduction of aromatic structure into phosphorus-containing aromatic flame retardant alcoholysis agent makes its structure similar to that of unsaturated polyester, which conforms to the principle of like dissolves like.

[0018] (3) Non-metallic ionic liquid catalysts can promote the occurrence of alcoholysis reaction and can be effectively recovered by water washing after the reaction, thus allowing for recycling.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is the reaction route diagram of Example 1; Figure 2 This is the reaction route diagram for Comparative Example 1; Figure 3 The 6-((1,3-dihydroxypropyl-2-yl)oxy)dibenzo[c,e][1,2]oxaphosphine-6-oxide in Example 1 1 HNMR spectrum; Figure 4NMR of formate choline in Example 1 1 HNMR spectrum; Figure 5 The FTIR curves of the products prepared in Example 1 and Comparative Example 1 are shown. Figure 6 Stability comparison curves of the products prepared in Example 1 and Comparative Example 1; Figure 7 The flame retardant performance comparison curves are shown for the products prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0023] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0024] Example 1 This embodiment provides a flame-retardant functional degradation method for unsaturated polyesters. A phosphorus-containing flame-retardant alcoholysis system is constructed by uniformly mixing 20g of 6-((1,3-dihydroxypropyl-2-yl)oxy)dibenzo[c,e][1,2]oxaphosphine-6-oxide and 1g of choline formate. The 6-((1,3-dihydroxypropyl-2-yl)oxy)dibenzo[c,e][1,2]oxaphosphine-6-oxide... 1 H NMR spectrum as shown Figure 1 As shown, the NMR of formate choline 1 HNMR spectrum as follows Figure 2 As shown.

[0025] 5g of unsaturated polyester powder passing through a 50-mesh sieve was added to the phosphorus-containing flame-retardant alcoholysis system, placed in a hydrothermal reactor, and reacted at 190℃ for 5 hours. The mixture was washed multiple times with water to obtain the prepared product – a flame-retardant polyol. The reaction route is as follows: Figure 3 As shown.

[0026] Comparative Example 1 20g of ethylene glycol and 1g of choline formate were mixed evenly, and then 5g of unsaturated polyester cured powder (passed through a 50-mesh sieve) was added. The mixture was placed in a hydrothermal reactor and reacted at 190℃ for 5 hours. The product was obtained by washing with water multiple times – a conventional non-flame-retardant degradation product. The reaction route is as follows: Figure 4 As shown.

[0027] Figure 5 The FTIR curves are of the flame-retardant polyol prepared in Example 1 and the conventional non-flame-retardant degradation product prepared in Comparative Example 1. The flame-retardant polyol of Example 1 has an FTIR curve at 1377 cm⁻¹. -1 The presence of a P=O peak indicates the introduction of a phosphorus-containing structure.

[0028] Figure 6 This is a comparison chart of the thermal stability of the flame-retardant polyol prepared in Example 1 and the conventional non-flame-retardant degradation product prepared in Comparative Example 1. The conventional non-flame-retardant degradation product obtained in Comparative Example 1 has a char residue of only 11.09 wt% at 800°C, while the flame-retardant polyol obtained in Example 1 has a char residue of 28.91 wt% at 800°C. Therefore, compared with the conventional non-flame-retardant degradation product obtained in Comparative Example 1, the flame-retardant polyol obtained in Example 1 has higher high-temperature thermal stability.

[0029] Figure 7 This is a comparison chart of the flame-retardant properties of the flame-retardant polyol prepared in Example 1 and the conventional non-flame-retardant degradation product prepared in Comparative Example 1. Compared with the conventional non-flame-retardant degradation product obtained in Comparative Example 1, the peak heat release rate of the flame-retardant polyol obtained in Example 1 decreased from 264 W / g to 133 W / g, a reduction of up to 49.6%. Therefore, the flame-retardant polyol prepared in Example 1 has excellent flame-retardant properties.

[0030] Example 2 This embodiment provides a method for the flame-retardant functionalization degradation of unsaturated polyester. A phosphorus-containing flame-retardant alcoholysis system is constructed by uniformly mixing 20g of 1,3-dihydroxypropyl-2-yldiphenylphosphine ester and 2g of acetic choline. 5g of unsaturated polyester powder passing through a 100-mesh sieve is added to this phosphorus-containing flame-retardant alcoholysis system, and the mixture is placed in a hydrothermal reactor and reacted at 200°C for 10 hours. The mixture is then washed multiple times with water to obtain a flame-retardant polyol.

[0031] Example 3 This embodiment provides a method for the flame-retardant functionalization degradation of unsaturated polyester. A phosphorus-containing flame-retardant alcoholysis system is constructed by uniformly mixing 20g of 6-((bis(2-hydroxyethyl)amino)methyl)dibenzo[c,e][1,2]oxaphosphine-6-oxide and 1g of formic acid choline. 5g of unsaturated polyester powder passing through a 100-mesh sieve is added to this phosphorus-containing flame-retardant alcoholysis system, and the mixture is placed in a hydrothermal reactor and reacted at 210°C for 10 hours. The mixture is then washed multiple times with water to obtain a flame-retardant polyol.

[0032] Therefore, the present invention provides a method that not only improves the solubility and site selectivity of the alcoholysis system of unsaturated polyester, but also endows the degradation products with specific properties, thereby promoting the transformation of unsaturated polyester waste into functional high-value-added products.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A flame retardant functional degradation method for unsaturated polyester, characterized in that: The flame retardant functionalized degradation method of unsaturated polyester constructs a phosphorus-containing flame retardant alcoholysis system to react with the unsaturated polyester, promotes the alcoholysis reaction of the unsaturated polyester, introduces a phosphorus-containing structure, and obtains a functionalized degradation product, wherein the functionalized degradation product is a flame retardant polyol.

2. The flame retardant functional degradation method of unsaturated polyester according to claim 1, characterized in that: The specific steps are as follows: S1. The unsaturated polyester solidified material is crushed into powder and passed through a 40-100 mesh sieve; S2. Add the unsaturated polyester solidified powder into the phosphorus-containing flame retardant alcoholysis system and mix evenly, place in a hydrothermal kettle, and react at a temperature range of 150-210° C. for 2-10 hours to obtain a flame retardant polyol.

3. The flame retardant functional degradation method of unsaturated polyester according to claim 2, characterized in that: In step S2, the mass ratio of the unsaturated polyester cured powder to the phosphorus-containing flame retardant alcoholysis system is 1:(1-5).

4. The flame retardant functional degradation method of unsaturated polyester according to claim 2, characterized in that: In step S2, the phosphorus-containing flame retardant alcoholysis system includes a phosphorus-containing aromatic flame retardant alcoholysis agent and an ionic liquid catalyst.

5. The flame retardant functional degradation method of unsaturated polyester according to claim 3, characterized in that: The mass ratio of the phosphorus-containing aromatic flame retardant alcoholysis agent to the ionic liquid catalyst is (10-40):

1.

6. The flame retardant functional degradation method of unsaturated polyester according to claim 4, characterized in that: The phosphorus-containing aromatic flame retardant alcoholysis agent is one or more of 6-((1,3-dihydroxypropan-2-yl)oxy)dibenzo[c,e][1,2]oxaphosphine-6-oxide, 1,3-dihydroxypropan-2-yl diphenyl phosphinate, 1,3-dihydroxypropan-2-yl diphenyl phosphate, 6-((bis(2-hydroxyethyl)amino)methyl)dibenzo[c,e][1,2]oxaphosphine-6-oxide, ((bis(2-hydroxyethyl)amino)methyl)diphenylphosphine oxide, and ((bis(2-hydroxyethyl)amino)methyl)diphenyl phosphine ester.

7. The flame retardant functional degradation method of unsaturated polyester according to claim 3, characterized in that: The ionic liquid catalyst is one or more of choline formate, choline acetate, choline hydrogen sulfate or choline phosphorylation.

8. A flame retardant polyol, characterized in that: The flame retardant polyol is obtained by degradation using the flame retardant functional degradation method of an unsaturated polyester according to any one of claims 1 to 7.

9. A flame retardant polyol according to claim 8, characterized in that: The flame retardant polyol is used in synthesizing polyurethane and unsaturated polyester materials.

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