Method for preparing phenoxy resin from thermosetting resin degradation product

Abstract

The invention discloses a method for preparing phenoxy resin from a thermosetting resin degradation product, and belongs to the technical field of thermoplastic resin material synthesis and thermosetting resin recycling. In order to solve the problems of large catalyst dosage, high component cost, difficulty in reutilization of a thermosetting resin chemical degradation product and the like in the existing phenoxy resin synthesis process, the thermosetting resin degradation product and epoxy resin are uniformly mixed according to a certain ratio and then subjected to a ring-opening reaction under a heating condition, and the phenoxy resin is obtained. The thermoplastic phenoxy resin can be formed after the reaction. A thermosetting resin degradation product difficult to treat is used as a core raw material to replace an expensive bisphenol A monomer, and the high-value thermoplastic phenoxy resin is directly synthesized through a hydroxyl-epoxy group ring-opening addition polymerization reaction with epoxy resin. While high-valued cyclic utilization of wastes is realized, the use amount of the catalyst in the phenoxy resin synthesis process is remarkably reduced, the process is simplified, and the raw material cost and the process cost are greatly reduced from the source.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoplastic resin material synthesis and thermosetting resin recycling and reuse, and particularly relates to a method for preparing phenoxy resin from thermosetting resin degradation products. Background Art

[0002] Phenoxy resin is a thermoplastic resin with excellent properties, characterized by good heat resistance, electrical insulation, adhesion, and chemical resistance. Due to its excellent performance, it is widely used in coatings, adhesives, electronic packaging, composite materials, and other fields. In addition, phenoxy resin has similar structures to epoxy resins and is therefore often used to toughen bisphenol A epoxy resin. Currently, the synthesis method of phenoxy resin is mainly to polycondense bisphenol A with epichlorohydrin under alkaline conditions, or to react a difunctional epoxy resin with bisphenol A. Patent CN116284732A discloses a halogen-free, highly flame-retardant, high-heat-resistant phenoxy resin and its preparation method. The method is obtained by mixing bisphenol diglycidyl ether, phenolic hydroxy triphosphazene epoxy monomer, bisphenol monomer, and a catalyst and then heating. Patent CN116970146A discloses a bio-based solid phenoxy resin and its preparation method. This method involves mixing a bio-based epoxy resin, bio-based bisphenol, and a catalyst in a specific proportion, heating the mixture to 170-220°C for reaction, and producing the bio-based solid phenoxy resin. Both of the aforementioned methods for synthesizing phenoxy resin require a catalyst, and the resin components are relatively expensive.

[0003] Common thermosetting resins (amine-cured epoxy resins, anhydride-cured epoxy resins, and vinyl ester resins) all contain a chemical structure similar to that of phenoxy resins. When chemically degraded, one of the products is bisphenol diglycerol ether. However, due to the ring-opening of the epoxy ring, the reactivity of this degradation product is reduced, making it difficult to directly utilize. Summary of the Invention

[0004] In view of the problems of large catalyst dosage, high component cost and difficulty in reusing chemical degradation products of thermosetting resin in the current phenoxy resin synthesis process, the present invention provides a method for preparing phenoxy resin from thermosetting resin degradation products.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing phenoxy resin from thermosetting resin degradation products comprises the following steps: mixing the thermosetting resin degradation products with epoxy resin in a specific proportion, uniformly mixing, and then subjecting the mixture to a ring-opening reaction under heating to form a thermoplastic phenoxy resin. This method utilizes the difficult-to-process thermosetting resin degradation products (containing active hydroxyl groups) as a core raw material, replacing the expensive bisphenol A monomer. Through a hydroxyl-epoxy ring-opening addition polymerization reaction with epoxy resin, a high-value thermoplastic phenoxy resin is directly synthesized. While achieving high-value recycling of waste, it significantly reduces the amount of catalyst used in the phenoxy resin synthesis process and simplifies the process, significantly reducing raw material and process costs at the source.

[0007] Further, the structure of the thermoplastic phenoxy resin is:

[0008] ; where X is: or or or or The resulting phenoxy resin has a weight-average molecular weight of 10,000 to 40,000 g / mol. The X in the phenoxy resin molecule is primarily related to the molecular structure of the thermosetting resin and the type of epoxy resin selected. This weight-average molecular weight range ensures the resin possesses both good mechanical and thermal processing properties.

[0009] Furthermore, the thermosetting resin degradation product is a compound having the following structure obtained by chemically recovering an amine-cured epoxy resin, an anhydride-cured epoxy resin or a vinyl ester resin:

[0010] ;

[0011] Where X is: or or or or The thermosetting resin product of this structure contains hydroxyl groups at both ends, which makes it more reactive with the epoxy ring structure of the epoxy resin.

[0012] Furthermore, the chemical recovery method involves hydrolysis, alcoholysis, or aminolysis. Hydrolysis, alcoholysis, or aminolysis selectively breaks ester bonds (for anhydride-cured epoxy resins and vinyl ester resins) or CN bonds (for amine-cured epoxy resins) within the thermosetting resin molecule, thereby preserving the basic bisphenol-type diglyceryl ether structure and facilitating further utilization.

[0013] Furthermore, the epoxy resin is a glycidyl ether epoxy resin, which is the mainstream epoxy product in the current market and accounts for more than 85% of the total epoxy resin production in China.

[0014] Furthermore, the glycidyl ether epoxy resin includes one or a mixture of any of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, or brominated bisphenol A diglycidyl ether. These epoxy resins contain epoxy groups that can undergo ring-opening polymerization with hydroxyl groups in degradation products of thermosetting resins.

[0015] Furthermore, the mixing method can include direct mixing or adding an organic solvent and mixing uniformly followed by removal and recovery of the organic solvent. For low-viscosity epoxy resin and thermosetting resin degradation products, direct mixing can be used. For high-viscosity epoxy resin and thermosetting resin degradation products, an organic solvent can be added to mix into a single phase before removing the solvent by rotary evaporation to ensure uniformity during the reaction.

[0016] Furthermore, the added organic solvent is one or a mixture of any of the following: 1,4-dioxane, acetone, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These organic solvents can effectively dissolve the high-viscosity thermosetting resin degradation products and the epoxy resin, ensuring that the two are thoroughly mixed before the reaction.

[0017] Furthermore, the thermosetting resin degradation product is mixed with the epoxy resin in a mass ratio of 0.5 to 2:1, the heating temperature is 80°C to 170°C, and the reaction time is 2 to 12 hours. Within this mass ratio range, the active groups (such as hydroxyl groups) in the degradation product fully react with the epoxy groups in the epoxy resin, effectively controlling the molecular weight of the final product and avoiding problems such as low molecular weight and insufficient performance. Within this temperature and reaction time range, the resin degradation product fully reacts with the epoxy resin, while also avoiding problems such as molecular weight loss or increased byproducts caused by excessively high reaction temperatures or prolonged reaction times.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The process is simple and efficient: no complex catalytic system or harsh conditions are required, and the synthesis of phenoxy resin can be achieved by heating only, which significantly simplifies the process flow.

[0020] (2) Outstanding cost advantage: No additional catalyst is required during the synthesis process, and one of the core raw materials is directly derived from waste thermosetting resin degradation products that currently have no practical value, which greatly reduces the cost of raw materials.

[0021] (3) Significant environmental benefits: The high-value recycling of waste thermosetting resin degradation products is achieved, which significantly reduces the consumption of petrochemical resources such as virgin bisphenol A. At the same time, it avoids the potential pollution caused by the use of catalysts, achieving the dual goals of resource conservation and environmental friendliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 is the molecular weight of the phenoxy resin prepared in Example. DETAILED DESCRIPTION

[0024] To gain a deeper understanding of the present invention, we will provide a comprehensive and detailed description thereof. However, the present invention has various implementations and is not limited to the specific examples listed herein. These examples are presented to enhance a comprehensive understanding of the present disclosure.

[0025] Example 1

[0026] First, an anhydride-cured epoxy resin was hydrolyzed in a 10 wt% sodium hydroxide aqueous solution to obtain a degradation product containing active hydroxyl groups. Then, 5 g of the anhydride-cured epoxy resin degradation product and 10 g of epoxy resin (bisphenol A diglycidyl ether) were weighed and placed in a heat-resistant glass beaker and mixed evenly. The beaker was then placed in a drying oven and heated to 80°C for 2 h. After the reaction was completed, the phenoxy resin was injected into a polytetrafluoroethylene mold while it was still hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 9.3 MPa, and the weight-average molecular weight (M (w) ) is 10020 g / mol.

[0027] Example 2

[0028] First, an anhydride-cured epoxy resin was subjected to aminolysis in a 15 wt% aqueous solution of ethylenediamine to obtain a degradation product containing active hydroxyl groups. Then, 5 g of the anhydride-cured epoxy resin degradation product and 10 g of epoxy resin (brominated bisphenol A diglycidyl ether) were weighed, mixed, and added with 1, 4-dioxane. After the solution completely became one phase, the solvent was removed and recovered on a rotary evaporator. The mixed liquid was then transferred to a heat-resistant beaker and placed in a drying oven heated to 80°C for 2 h. After the reaction was completed, the phenoxy resin was injected into a polytetrafluoroethylene mold while hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 11.3 MPa, and the weight-average molecular weight (M (w) ) is 15740 g / mol.

[0029] Example 3

[0030] First, the amine-cured epoxy resin was hydrolyzed in a 15 wt% hydrochloric acid aqueous solution to obtain a degradation product containing active hydroxyl groups. Then, 5 g of the amine-cured epoxy resin degradation product and 5 g of epoxy resin (bisphenol F diglycidyl ether) were weighed and placed in a heat-resistant glass beaker and mixed evenly. The beaker was then placed in a drying oven and heated to 130 °C for 7 h. After the reaction was completed, the phenoxy resin was injected into a polytetrafluoroethylene mold while it was still hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 17.1 MPa, and the weight-average molecular weight (M (w) ) is 20411g / mol.

[0031] Example 4

[0032] First, the amine-cured epoxy resin was hydrolyzed in a 15 wt% hydrochloric acid aqueous solution to obtain a degradation product containing active hydroxyl groups. Then, 5 g of the amine-cured epoxy resin degradation product and 5 g of epoxy resin (bisphenol S diglycidyl ether) were weighed and placed in a heat-resistant glass beaker and mixed evenly. The beaker was then placed in a drying oven and heated to 150°C for 10 hours. After the reaction, the phenoxy resin was injected into a polytetrafluoroethylene mold while it was still hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 20.6 MPa, and the weight-average molecular weight (M (w) ) is 27335 g / mol ( Figure 1 ).

[0033] Example 5

[0034] First, vinyl ester resin was subjected to alcoholysis in 8 wt% potassium hydroxide ethanol solution to obtain a degradation product containing active hydroxyl groups. Then, 10 g of the vinyl ester resin degradation product and 5 g of epoxy resin (bisphenol A diglycidyl ether) were weighed and placed in a heat-resistant glass beaker and mixed evenly. The beaker was then placed in a drying oven and heated to 170°C for 12 h. After the reaction was completed, the phenoxy resin was injected into a polytetrafluoroethylene mold while it was still hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 14.6 MPa, and the weight-average molecular weight (M (w) ) is 15373 g / mol.

[0035] Example 6

[0036] First, vinyl ester resin was subjected to alcoholysis in 8 wt% potassium hydroxide ethanol solution to obtain a degradation product containing active hydroxyl groups. Then, 5 g of the degradation product of vinyl ester resin and 5 g of epoxy resin (hydrogenated bisphenol A diglycidyl ether) were weighed and placed in a heat-resistant glass beaker and mixed evenly. The beaker was then placed in a drying oven and heated to 170 °C for 12 h. After the reaction was completed, the phenoxy resin was injected into a polytetrafluoroethylene mold while it was still hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 27.4 MPa, and the weight-average molecular weight (M (w) ) is 35373 g / mol.

[0037] Example 7

[0038] First, an anhydride-cured epoxy resin was hydrolyzed in a 10 wt% potassium hydroxide aqueous solution to obtain a degradation product containing active hydroxyl groups. Then, 5 g of the anhydride-cured epoxy resin degradation product and 5 g of epoxy resin (brominated bisphenol A diglycidyl ether) were weighed, mixed, and added with tetrahydrofuran. After the solution completely became one phase, the solvent was removed and recovered on a rotary evaporator. The mixed liquid was then transferred to a heat-resistant beaker and placed in a drying oven heated to 160 °C for 8 h. After the reaction was completed, the phenoxy resin was injected into a polytetrafluoroethylene mold while hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 26.9 MPa, and the weight-average molecular weight (M (w) ) is 38241 g / mol.

[0039] Example 8

[0040] First, an anhydride-cured epoxy resin was hydrolyzed in a 10 wt% hydrochloric acid aqueous solution to obtain a degradation product containing active hydroxyl groups. Then, 5 g of the anhydride-cured epoxy resin degradation product and 8 g of epoxy resin (bisphenol A diglycidyl ether) were weighed and placed in a heat-resistant glass beaker and mixed evenly. The beaker was then placed in a drying oven and heated to 170 °C for 12 h. After the reaction was completed, the phenoxy resin was injected into a polytetrafluoroethylene mold while it was still hot. After cooling, the thermoplastic phenoxy resin was subjected to tensile strength and molecular weight tests. The obtained data are as follows: the tensile strength is 16.2 MPa, and the weight-average molecular weight (M (w) ) is 21375 g / mol.

[0041] Any matters not described in detail in this specification are prior art known to those skilled in the art. Although the above description of the present invention is based on specific embodiments to facilitate understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the specific embodiments. As long as various modifications are within the spirit and scope of the present invention as defined and determined by the appended claims, such modifications will be obvious to those skilled in the art, and all inventions and creations utilizing the concepts of the present invention are protected.

Claims

1. A thermoplastic phenoxy resin, characterized in that The structure of the phenoxy resin is: ; where X is: or or or or The weight average molecular weight of the obtained phenoxy resin is 10,000 to 40,000 g / mol.

2. A method for preparing a phenoxy resin from a thermosetting resin degradation product, characterized in that: The degradation product of the thermosetting resin is mixed with the epoxy resin in a certain proportion, and after being evenly mixed, a ring-opening reaction is carried out under heating conditions to form a thermoplastic phenoxy resin.

3. The method for preparing a phenoxy resin from a thermosetting resin degradation product according to claim 2, wherein: The thermosetting resin degradation product is a compound having the following structure, which is prepared by a chemical recovery method from an amine-cured epoxy resin, an anhydride-cured epoxy resin or a vinyl ester resin: ; Where X is: or or or or .

4. The method for preparing a phenoxy resin from a thermosetting resin degradation product according to claim 3, wherein: The chemical recovery method is hydrolysis, alcoholysis or aminolysis.

5. The method for preparing phenoxy resin from a thermosetting resin degradation product according to claim 2, wherein: The epoxy resin is a glycidyl ether epoxy resin.

6. The method for preparing a phenoxy resin from a thermosetting resin degradation product according to claim 2, wherein: The glycidyl ether epoxy resin includes one or a mixture of any proportion of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, hydrogenated bisphenol A diglycidyl ether or brominated bisphenol A diglycidyl ether.

7. The method for preparing phenoxy resin from a thermosetting resin degradation product according to claim 2, wherein: The mixing mass ratio of the thermosetting resin degradation product to the epoxy resin is 0.5-2:

1.

8. The method for preparing phenoxy resin from a thermosetting resin degradation product according to claim 2, wherein: The mixing method is direct mixing, or adding an organic solvent, mixing evenly, and then removing and recovering the organic solvent.

9. The method for preparing phenoxy resin from a thermosetting resin degradation product according to claim 8, wherein: The organic solvent is one or a mixture of any ratio of 1,4-dioxane, acetone, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide or N,N-dimethylacetamide.

10. The method for preparing phenoxy resin from a thermosetting resin degradation product according to claim 3, wherein: The ring-opening reaction is carried out at a heating temperature of 80° C. to 170° C., and the reaction time is 2 h to 12 h.

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