A method for degrading silicone resin with a phenolic compound

Abstract

The application belongs to the technical field of degradation of thermosetting silicon resin, and particularly discloses a method for degrading silicon resin by using phenolic compounds. In the application, the hybrid exchange reaction between the phenolic hydroxyl of the phenolic compound and the Si-O-Si bond in the silicon resin makes the Si-O-Si bond broken, so that the silicon resin is degraded.

Description

Technical Field

[0001] This invention belongs to the field of thermosetting silicone resin degradation technology, specifically relating to a method for degrading silicone resin with phenolic compounds. Background Technology

[0002] Thermosetting resins have become irreplaceable materials due to their excellent heat resistance, high strength, corrosion resistance, and aging resistance. However, the irreversible cross-linked covalent bond structure within thermosetting resins makes them difficult to recycle, resulting in significant resource waste and environmental pollution.

[0003] Silicone resins are thermosetting polymers with a highly cross-linked structure. Common types include methyl silicone resins, methylphenyl silicone resins, phenyl silicone resins, vinyl silicone resins, and MQ silicone resins. Because thermosetting silicone resins possess the dual properties of both organic and inorganic materials, their use is increasing in modern society. However, the unique structural characteristics of thermosetting resins make them difficult to reprocess, leading to significant environmental pollution problems. Summary of the Invention

[0004] To address the above problems, this invention provides a method for degrading thermosetting silicone resins with phenolic compounds. Specifically, it is based on the hybridization exchange reaction between the phenolic hydroxyl groups of phenolic substances and the Si-O-Si bonds in the thermosetting silicone resin, causing the Si-O-Si bonds to break, thereby degrading the thermosetting silicone resin. A more detailed internal reaction mechanism is as follows: Figure 1 As shown.

[0005] To solve the above technical problems, the technical solution provided by this invention is as follows:

[0006] A method for degrading silicone resin with phenolic substances is specifically based on the hybridization exchange reaction between the phenolic hydroxyl groups of the phenolic substances and the Si-O-Si bonds in the silicone resin, causing the Si-O-Si bonds to break and thus degrading the silicone resin. A more detailed internal reaction mechanism is as follows... Figure 1 As shown, the phenolic hydroxyl groups of the phenolic substances attack the Si-O bonds, breaking the Si-O-Si bond and thus achieving the degradation of the silicone resin.

[0007] The chemical formula of the phenolic substances is shown in formula (I):

[0008]

[0009] In formula (I), R1 is an aromatic group; n represents the hydroxyl content of phenolic substances and is an integer from 1 to 4.

[0010] The chemical formula of the silicone resin is shown in formula (II):

[0011]

[0012] In formula (II), R1, R2, and R3 are one or more of methyl, vinyl, and phenyl groups, more preferably one or more of methyl and phenyl groups.

[0013] The specific steps are as follows:

[0014] (1) Mix the silicone resin and phenolic substances and put them into a reaction flask;

[0015] (2) Increase the temperature to carry out the reaction;

[0016] (3) After the reaction, it was observed that the solid silicone resin was completely degraded and the reactants became a homogeneous system.

[0017] The reaction process needs to be carried out under an inert atmosphere.

[0018] The silicone resin is a thermosetting polymer containing Si-O-Si bonds, preferably methylphenyl silicone resin or methyl silicone resin.

[0019] The phenolic substances are phenol, bisphenol A, p-cresol, and p-bromophenol.

[0020] The mass ratio of the silicone resin to the phenolic substance is 1:(1-100); preferably 1:(1-20).

[0021] Preferably, the silicone resin is mixed with phenolic substances and then a catalyst is added.

[0022] The catalysts include, but are not limited to, tetraethoxytitanium, dibutyltin oxide, and zinc acetate.

[0023] Preferably, the amount of catalyst added is 0 to 10 wt% of the silicone resin mass.

[0024] In step (2), the reaction process is carried out in an inert atmosphere.

[0025] In step (2), the reaction time is 1 to 36 hours, preferably 12 to 24 hours;

[0026] The reaction temperature is 100–400°C, preferably 200–350°C.

[0027] The silicone resin includes commercial silicone resin and laboratory-synthesized silicone resin.

[0028] Beneficial effects:

[0029] 1. This invention is the first to propose using a hybrid exchange reaction between phenolic hydroxyl groups and Si-O-Si bonds to achieve the degradation of silicone resin;

[0030] 2. This invention uses phenolic hydroxyl groups to degrade silicone resin. The degradation process is safe and simple, providing a new research direction for the degradation of silicone resin. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, some simple figures will be drawn below to describe the sample data characterization process in the implementation of the present invention.

[0032] Figure 1 This is a schematic diagram of the hybridization exchange reaction between phenolic hydroxyl groups and Si-O-Si bonds;

[0033] Figure 2 This is a comparison diagram of the methylphenyl silicone resin before and after degradation by phenol in Example 1;

[0034] Figure 3 This is a comparison of the infrared spectra of methylphenyl silicone resin before and after degradation by phenol in Example 1;

[0035] Figure 4 This is a gel permeation chromatogram of methylphenyl silicone resin after degradation by phenol in Example 1;

[0036] Figure 5 This is a comparison of the infrared spectra of methylphenyl silicone resin before and after degradation by p-cresol in Example 8;

[0037] Figure 6 This is a comparison of the infrared spectra of methylphenyl silicone resin before and after degradation by bisphenol A in Example 9. Detailed Implementation

[0038] Example 1

[0039] A method for degrading methylphenyl silicone resin with phenol involves first taking 0.02 g of methylphenyl silicone resin. The methylphenyl silicone resin and phenol are mixed at a mass ratio of 1:10 and placed in a reaction flask. Then, dibutyltin oxide is added, with the amount of dibutyltin oxide being 0.1 wt% of the mass of the methylphenyl silicone resin. The reaction system is then evacuated to a vacuum and protected with argon gas. This operation is repeated three times. The reaction system is heated to 300°C and reacted for 24 h. Finally, the methylphenyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0040] like Figure 2 These are comparison images of methylphenyl silicone resin before and after degradation by phenol; the left image shows the methylphenyl silicone resin before degradation, and the right image shows the methylphenyl silicone resin after degradation. The images clearly show that the methylphenyl silicone resin has been completely degraded.

[0041] Figure 3The image shows a comparison of the infrared spectra of methylphenyl silicone resin before and after degradation by phenol. Figure a shows the infrared spectrum of methylphenyl silicone resin after degradation by phenol, b shows the infrared spectrum of methylphenyl silicone resin before degradation, and c shows the infrared spectrum of phenol. The figures show that new Si-O-Ph bonds were formed after the degradation of methylphenyl silicone resin by phenol, proving that the phenolic hydroxyl groups on the phenol attacked the Si-O-Si bonds to form new Si-O-Ph bonds.

[0042] Figure 4 This is a gel permeation chromatogram of methylphenyl silicone resin after degradation by phenol. In the figure, a represents the degradation of methylphenyl silicone resin by phenol, b represents the degradation of methylphenyl silicone resin by p-bromophenol, and c represents the degradation of methylphenyl silicone resin by p-cresol. The weight-average molecular weight and number-average molecular weight of all three are less than 2000, indicating that the large molecules have been converted into smaller molecules, proving that the silicone resin has been degraded.

[0043] Example 2

[0044] A method for degrading methyl silicone resin with phenol involves first taking 0.01 g of methyl silicone resin and mixing it with phenol at a mass ratio of 1:15, then placing the mixture in a reaction flask. Dibutyltin oxide is added, with the amount of dibutyltin oxide being 0.1 wt% of the mass of the methyl silicone resin. The reaction system is then evacuated to a vacuum and protected with argon gas. This process is repeated three times. The reaction system is then heated to 300°C and reacted for 24 hours. Finally, the methyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0045] Example 3

[0046] A method for degrading methylphenyl silicone resin with bisphenol A involves first taking 0.015 g of methylphenyl silicone resin. The methylphenyl silicone resin and bisphenol A are mixed at a mass ratio of 1:20, and then placed in a reaction flask. Tetraethoxytitanium is added, with the amount of tetraethoxytitanium being 0.1 wt% of the mass of the methylphenyl silicone resin. The reaction system is evacuated and then protected with nitrogen gas. This operation is repeated three times. The reaction system is heated to 300°C and reacted for 12 hours. Finally, the methylphenyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0047] Example 4

[0048] A method for degrading methylphenyl silicone resin with p-cresol involves first taking 0.02 g of methylphenyl silicone resin. The methylphenyl silicone resin and p-cresol are mixed at a mass ratio of 1:15 and then placed in a reaction flask. Dibutyltin oxide is added, with the amount of dibutyltin oxide being 0.1 wt% of the mass of the methylphenyl silicone resin. The reaction system is evacuated and then protected with argon gas. This operation is repeated three times. The reaction system is heated to 250°C and reacted for 12 h. Finally, the methylphenyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0049] Example 5

[0050] A method for degrading methylphenyl silicone resin with p-bromophenol involves first taking 0.01 g of methylphenyl silicone resin. The methylphenyl silicone resin is mixed with bisphenol A at a mass ratio of 1:20, and then placed in a reaction flask. Tetraethoxytitanium is added, with the amount of tetraethoxytitanium being 0.2 wt% of the methylphenyl silicone resin mass. The reaction system is evacuated and then protected with argon gas. This operation is repeated three times. The reaction system is heated to 250°C and reacted for 24 h. Finally, the methylphenyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0051] Example 6

[0052] A method for degrading methyl silicone resin with bisphenol A involves first taking 0.01 g of methyl silicone resin. The methyl silicone resin and bisphenol A are mixed at a mass ratio of 1:25, and then placed in a reaction flask. Tetraethoxytitanium is added, with the amount of tetraethoxytitanium being 0.1 wt% of the mass of the methyl silicone resin. The reaction system is evacuated to a vacuum and then protected with argon gas. This operation is repeated three times. The reaction system is heated to 250°C and reacted for 12 hours. Finally, the methyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0053] Example 7

[0054] A method for degrading methyl silicone resin with p-cresol involves first taking 0.02 g of methyl silicone resin. The methyl silicone resin and bisphenol A are mixed at a mass ratio of 1:10, and then placed in a reaction flask. Dibutyltin oxide is added, with the amount of dibutyltin oxide being 0.2 wt% of the mass of the methyl silicone resin. The reaction system is evacuated to a vacuum and then protected with argon gas. This operation is repeated three times. The reaction system is heated to 250°C and reacted for 12 hours. Finally, the methyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0055] Example 8

[0056] A method for degrading methylphenyl silicone resin with p-cresol involves first taking 0.03 g of methylphenyl silicone resin. The methylphenyl silicone resin and p-cresol are mixed at a mass ratio of 1:20 and then placed in a reaction flask. The reaction system is evacuated and protected with argon gas; this process is repeated three times. The reaction system is then heated to 250°C and reacted for 12 hours. Finally, the methylphenyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0057] like Figure 5The image shows a comparison of the infrared spectra of methylphenyl silicone resin before and after degradation by p-cresol. Figure a shows the infrared spectrum of methylphenyl silicone resin after degradation by p-cresol, b shows the infrared spectrum of methylphenyl silicone resin before degradation, and c shows the infrared spectrum of p-cresol. The figures show that new Si-O-Ph bonds were formed after the degradation of methylphenyl silicone resin by p-cresol, proving that the phenolic hydroxyl groups on p-cresol attacked the Si-O-Si bonds to form new Si-O-Ph bonds.

[0058] Example 9

[0059] A method for degrading methylphenyl silicone resin with bisphenol A involves first taking 0.02 g of methylphenyl silicone resin. The methylphenyl silicone resin and bisphenol A are mixed at a mass ratio of 1:20, and then placed in a reaction flask. The reaction system is evacuated and protected with nitrogen gas. This process is repeated three times. The reaction system is then heated to 300°C and reacted for 12 hours. Finally, the methylphenyl silicone resin is completely degraded, and the reactants become a homogeneous system.

[0060] like Figure 6 The image shows a comparison of the infrared spectra of methylphenyl silicone resin before and after degradation by bisphenol A. Figure a shows the infrared spectrum of methylphenyl silicone resin after degradation by bisphenol A, b shows the infrared spectrum of methylphenyl silicone resin before degradation, and c shows the infrared spectrum of bisphenol A. The figures show that new Si-O-Ph bonds were formed after the degradation of methylphenyl silicone resin by bisphenol A, proving that the phenolic hydroxyl groups on bisphenol A attacked the Si-O-Si bonds to form new Si-O-Ph bonds.

Claims

1. A method for degrading silicone resin with phenolic compounds, characterized in that, The phenolic hydroxyl groups of phenolic substances undergo a hybrid exchange reaction with the Si-O-Si bonds in silicone resin, causing the Si-O-Si bonds to break and thus degrading the silicone resin. The silicone resin is a thermosetting polymer containing Si-O-Si bonds. The chemical formula of the phenolic substances is shown in formula (I): (I)； In formula (I), R1 is an aromatic group; n represents the hydroxyl content of phenolic substances, which is an integer from 1 to 4; The chemical formula of the silicone resin is shown in formula (II): (II); In formula (II), R1, R2, and R3 are one or more of methyl, vinyl, and phenyl groups; The specific steps for phenolic compounds to degrade silicone resin are as follows: (1) Mix phenolic substances and silicone resin; (2) The reaction is carried out by heating; the reaction temperature is 100°C. o C-400 o C, reaction time is 1-36 h; (3) After the reaction, it was observed that the thermosetting silicone resin was completely degraded and became a homogeneous system; The reaction process takes place entirely in an inert gas system.

2. The method for degrading silicone resin with phenolic compounds according to claim 1, characterized in that, In formula (II), R1, R2, and R3 are one or more of methyl and phenyl.

3. The method for degrading silicone resin with phenolic compounds according to claim 1, characterized in that, The silicone resin is methylphenyl silicone resin or methyl silicone resin; The phenolic substances are phenol, bisphenol A, p-cresol, and p-bromophenol.

4. The method for degrading silicone resin with phenolic compounds according to claim 1, characterized in that, In step (1), a catalyst is added after the phenolic substance and silicone resin are mixed.

5. The method for degrading silicone resin with phenolic compounds according to claim 4, characterized in that, The catalyst includes one of tetraethoxytitanium, dibutyltin oxide, and zinc acetate.

6. The method for degrading silicone resin with phenolic compounds according to claim 1, characterized in that, The mass ratio of the silicone resin to the phenolic substance is 1:(1~100).

7. The method for degrading silicone resin with phenolic compounds according to claim 6, characterized in that, The mass ratio of the silicone resin to the phenolic substance is 1:(1~20).

8. The method for degrading silicone resin with phenolic compounds according to claim 1, characterized in that, The reaction time is 12-24 hours; the reaction temperature is 200°C. o C-350 o C.

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