Degradable rosin-based epoxy foam as well as preparation method and application thereof

Abstract

The invention discloses degradable rosinyl epoxy foam and a preparation method and application thereof, and belongs to the technical field of shielding materials, and the preparation method comprises the following steps: stirring and uniformly mixing a propylene diamine latent foaming agent, propylene diamine, acrylpimaric acid glycidyl ester and 1, 3-bis (3-glycidoxypropyl)-1, 1, 3, 3-tetramethyldisiloxane, and adding an initiator, a catalyst and a stabilizer to obtain a mixture; and reacting to obtain the degradable rosin-based epoxy foam. The foaming agent used in the invention is rapidly decomposed to release carbon dioxide and a curing agent propylene diamine under a heating condition, and is simple to prepare, environment-friendly and free of residues; the prepared epoxy foam is easy to degrade and excellent in electromagnetic shielding and Joule heating performance, and has wide application prospects in the fields of military equipment, aerospace, wearable electronic equipment and the like.

Description

Technical Field

[0001] The invention relates to a degradable rosin-based epoxy foam and a preparation method and application thereof, belonging to the technical field of shielding materials. Background Art

[0002] With the rapid development of portable electronic devices and communication technology, the problem of electromagnetic radiation pollution has become increasingly prominent, seriously affecting human health and the normal operation of electronic devices; therefore, efficient electromagnetic shielding materials have attracted people's attention; in addition, the thermal regulation performance of the material can achieve sensitive electrothermal conversion to meet its practical application in cold areas. However, traditional heating methods usually have high energy consumption or require a large area of ​​insulation layer, which not only causes energy waste but also increases the weight of the equipment, while Joule heating-driven temperature regulation shows great prospects due to its advantages such as high efficiency, convenience and energy saving. Therefore, it is urgent to develop materials with efficient electromagnetic shielding and excellent Joule heating performance to meet the requirements of advanced electronic devices.

[0003] At present, researchers have introduced conductive fillers or highly conductive metal coatings into polymer foams to construct conductive networks. The prepared conductive foams can not only effectively reduce the density of the material to meet the requirements of lightweight, but also enhance the attenuation of electromagnetic waves and improve electromagnetic shielding performance through multiple reflections and scattering inside the porous structure. However, such materials are often prepared based on traditional petrochemical derivatives and are not degradable, which not only leads to the consumption of non-renewable petroleum resources, but also causes serious pollution to the environment, limiting their widespread application in the field of electromagnetic shielding. Therefore, it is urgent to develop a bio-based degradable material with high-efficiency electromagnetic shielding and Joule heating performance.

[0004] Epoxy foam has the properties of light weight, good heat insulation and stability, and is widely used in parts weight reduction, thermal insulation and other fields. However, thermosetting epoxy foam is difficult to degrade and recycle, and the current preparation of epoxy foam mostly uses sodium bicarbonate, supercritical CO2 and other foaming agents, and the production process is complex and the cost is high. In view of the needs of sustainable development and environmental friendliness, degradable bio-based epoxy foam materials have gradually attracted the attention of researchers. Summary of the invention

[0005] In order to solve the defects of poor performance and non-degradability of electromagnetic shielding materials in the prior art, the present invention provides a degradable rosin-based epoxy foam and a preparation method and application thereof, so as to prepare a degradable rosin-based epoxy foam with high-efficiency electromagnetic shielding and Joule heating performance. The preparation method of the epoxy foam is simple, the foaming agent used has no residue, the cost is low, and the prepared epoxy foam material is easy to degrade and has excellent electromagnetic shielding and Joule heating performance.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A method for preparing a degradable rosin-based epoxy foam comprises the following steps:

[0008] Propylene diamine-based latent foaming agent, propylene diamine, propylene pimaric acid glycidyl ester and 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane are stirred and mixed to obtain a degradable rosin-based epoxy foam;

[0009] The preparation method of the propylene diamine-based latent foaming agent comprises dissolving propylene diamine in anhydrous ethanol at room temperature, introducing carbon dioxide gas to react for 2 to 4 hours, and obtaining the propylene diamine-based latent foaming agent;

[0010] The preparation method of acrylpimaric acid glycidyl ester comprises reacting acrylpimaric acid, epichlorohydrin and benzyltriethylammonium chloride at 110-117° C. for 3-5 hours, then cooling to 50-60° C., adding sodium hydroxide and continuing the reaction at 50-60° C. for 4-6 hours to obtain acrylpimaric acid glycidyl ester.

[0011] Preferably, the mass ratio of the propylene diamine-based latent foaming agent, propylene diamine, acrylpimaric acid glycidyl ester and 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane is (0.1-0.3):1:(5-11):(3-7).

[0012] Preferably, the reaction conditions in step (1) are: maintaining the temperature at 50-70° C. for 20-40 minutes, and then curing at a temperature of 120-160° C. for 1-4 hours.

[0013] Preferably, the mass ratio of acrylpimaric acid, epichlorohydrin, benzyltriethylammonium chloride and sodium hydroxide is (80-90):(400-410):1:(15-20).

[0014] The present invention also provides a degradable rosin-based epoxy foam, which is prepared by any one of the preparation methods.

[0015] At the same time, the invention provides the application of degradable rosin-based epoxy foam in electromagnetic materials.

[0016] Preferably, the application of the degradable rosin-based epoxy foam in electromagnetic materials comprises the following steps:

[0017] (1) immersing the degradable rosin-based epoxy foam in an acidic stannous chloride solution, sensitizing it at room temperature, and then washing it with deionized water for 10 to 30 minutes to obtain a sensitized degradable rosin-based epoxy foam;

[0018] (2) reacting the sensitized degradable rosin-based epoxy foam in a Tollens A solution for 0.5 to 1.5 hours to obtain a degradable rosin-based epoxy foam modified by a chemical reaction;

[0019] (3) Plating the modified degradable rosin-based epoxy foam in a mixture of a reducing solution and a silver salt solution for chemical plating for 1 to 2 hours, and after drying, repeating the process 1 to 3 times to obtain a degradable rosin-based epoxy foam with conductive properties.

[0020] Preferably, the acidic stannous chloride solution is prepared by dissolving stannous chloride dihydrate in a dilute hydrochloric acid solution to obtain an acidic stannous chloride solution;

[0021] The preparation method of the silver salt solution is as follows: sodium hydroxide is added to Tollens B solution and stirred, and then an ammonia solution is continuously added dropwise until the solution becomes clear, and the obtained transparent solution is the silver salt solution.

[0022] Preferably, the preparation method of the Tollens A and Tollens B solutions is to add an aqueous ammonia solution to a 3-5 g / L silver nitrate solution A and a 10-20 g / L silver nitrate solution B, respectively, until the solution changes from turbid to clear, to obtain a Tollens A and a Tollens B solution, respectively;

[0023] The reducing solution is prepared by dissolving tartaric acid, glucose, ethylenediamine, ethanol and polyethylene glycol in deionized water to obtain the reducing solution.

[0024] Preferably, the mass ratio of tartaric acid, glucose, ethylenediamine, ethanol and polyethylene glycol is 1:(8-10):(3-5):(45-50):(0.2-0.5).

[0025] The technologies not mentioned in the present invention are all referred to the prior art.

[0026] (1) The preparation method of the degradable rosin-based epoxy foam of the present invention is simple. The use of natural product derivatives to prepare the degradable rosin-based epoxy foam is in line with the concept of green development. The foaming agent used has no residue and low cost. The foaming agent used decomposes rapidly under heating conditions to release carbon dioxide and curing agent propylene diamine.

[0027] (2) The rosin-based epoxy foam prepared by the present invention is easy to degrade, and has excellent electromagnetic shielding and Joule heating properties. The electromagnetic shielding effectiveness can reach 76.37 dB. When driven by a voltage of 0.4 to 1.0 V, the surface temperature of the degradable rosin-based epoxy foam reaches a steady-state temperature within 90 seconds. The foam has broad application prospects in the fields of military equipment, aerospace, and wearable electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1The propylene diamine latent foaming agent prepared in Example 1 13 C NMR spectra;

[0029] Figure 2 This is a thermogravimetric analysis diagram of the propylene diamine-based latent foaming agent prepared in Example 1;

[0030] Figure 3 The propylene pimaric acid glycidyl ester obtained in Example 1 1 H NMR spectra;

[0031] Figure 4 This is the infrared spectrum of the degradable rosin-based epoxy foam prepared in Example 3;

[0032] Figure 5 The stress-strain curves of the degradable rosin-based epoxy foams prepared in Examples 1 to 4;

[0033] Figure 6 This is a reversible compression performance diagram of the degradable rosin-based epoxy foam prepared in Example 3;

[0034] Figure 7 This is a degradation diagram of the rosin-based epoxy foam prepared in Example 3;

[0035] Figure 8 This is an infrared comparison diagram of the rosin-based epoxy foam prepared in Example 3 before and after degradation;

[0036] Fig. 9 The electromagnetic shielding effectiveness diagram of the prepared silver-modified degradable rosin-based epoxy foam;

[0037] Fig.10 This is a Joule heating temperature change curve of the prepared silver-modified degradable rosin-based epoxy foam driven by a voltage of 0.4-1.0V. DETAILED DESCRIPTION

[0038] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] A method for preparing a degradable rosin-based epoxy foam comprises the following steps:

[0041] 10.0 g of propylenediamine (DP) and 50 mL of anhydrous ethanol were added to a 250 mL three-necked flask equipped with a mechanical stirrer and stirred to form a uniform solution. Then, CO2 gas was introduced into the solution at a flow rate of 80 mL / min through a gas guide tube. After bubbling was observed in the solution, the solution was stirred at a speed of 500 rpm for 3 hours, then the stirring was stopped, the white precipitate was filtered out, and a white powder propylenediamine-based latent foaming agent (DPC, 12.05 g) was obtained after drying.

[0042] 23.5 g of acrylpimaric acid, 116.0 g of epichlorohydrin and 0.286 g of benzyltriethylammonium chloride were reacted at 117° C. for 3 h, the system temperature was lowered to 60° C., 5.0 g of sodium hydroxide was added, and the reaction was continued at 60° C. for 3 h. After the reaction was completed, the mixture was cooled to room temperature, filtered to remove the precipitate, and the epichlorohydrin was removed from the filtrate by reduced pressure distillation to obtain a light yellow liquid, i.e. acrylpimaric acid glycidyl ester EAPA (27.92 g), with a yield of 91.42% and an epoxide value of 0.339 mol / 100 g.

[0043] 23.34 g of propylene pimaric acid glycidyl ester (EAPA), 7.47 g of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane (TMSEP), 0.6 g of propylenediamine-based latent foaming agent (DPC) and 2.2 g of propylenediamine (DP) were added to a disposable plastic cup and stirred at a rate of 1200 rpm for 3 min with a mechanical stirrer to obtain a light yellow emulsion. The emulsion was transferred to a paper cup coated with a release agent, placed in an oven at room temperature and heated to 70°C and maintained for 30 min, and finally heated to 120°C for curing for 2 h to obtain a degradable rosin-based epoxy foam F1.

[0044] Figure 1 The propylene diamine latent foaming agent prepared in Example 1 13 In the C NMR spectrum, the carbon peak of ionic carbamate appeared at 165.9 ppm, indicating that propylenediamine chemically absorbed carbon dioxide to form a carbamate structure; Figure 2 This is the thermogravimetric analysis diagram of the propylene diamine-based latent foaming agent prepared in Example 1, and its initial decomposition temperature is 84.1°C (weight loss 1%), indicating that it is stable at room temperature; Figure 3 is the propylene pimaric acid glycidyl ester obtained in Example 1 1 In the H NMR diagram, the proton peak of the methylene group in the epichlorohydrin structure appeared at 4.50-3.80 ppm, indicating that acrylpimaric acid glycidyl ester was successfully prepared.

[0045] Example 2

[0046] The preparation methods of EAPA and DPC are the same as those in Example 1.

[0047] 17.51 ​​g of propylene pimaric acid glycidyl ester (EAPA), 11.20 g of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane (TMSEP), 0.6 g of propylenediamine-based latent foaming agent (DPC) and 2.2 g of propylenediamine (DP) were added to a disposable plastic cup and stirred at a rate of 1200 rpm with a mechanical stirrer for 3 min to obtain a light yellow emulsion. The emulsion was transferred to a paper cup coated with a release agent, placed in an oven at room temperature and heated to 70°C and maintained for 30 min, and finally heated to 120°C for curing for 2 h to obtain a degradable rosin-based epoxy foam F2.

[0048] Example 3

[0049] The preparation methods of EAPA and DPC are the same as those in Example 1.

[0050] 14.02 g of propylene pimaric acid glycidyl ester (EAPA), 13.44 g of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane (TMSEP), 0.6 g of propylenediamine-based latent foaming agent (DPC) and 2.2 g of propylenediamine (DP) were added to a disposable plastic cup and stirred at a rate of 1200 rpm for 3 min with a mechanical stirrer to obtain a light yellow emulsion. The emulsion was transferred into a paper cup coated with a release agent, placed in an oven at room temperature and heated to 70°C and maintained for 30 min, and finally heated to 120°C for curing for 2 h to obtain a degradable rosin-based epoxy foam F3.

[0051] Example 4

[0052] The preparation methods of EAPA and DPC are the same as those in Example 1.

[0053] 11.68 g of propylene pimaric acid glycidyl ester (EAPA), 14.94 g of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane (TMSEP), 0.6 g of propylenediamine-based latent foaming agent (DPC) and 2.2 g of propylenediamine (DP) were added to a disposable plastic cup and stirred at a rate of 1200 rpm with a mechanical stirrer for 3 min to obtain a light yellow emulsion. The emulsion was transferred to a paper cup coated with a release agent, placed in an oven at room temperature and heated to 70°C and maintained for 30 min, and finally heated to 120°C for curing for 2 h to obtain a degradable rosin-based epoxy foam F4.

[0054] Application Examples

[0055] 1.2g stannous chloride dihydrate is dissolved in the dilute hydrochloric acid solution of 100mL 1.5vol%, and acidic stannous chloride solution is obtained. Subsequently, ammonia solution is added to 100mL silver nitrate solution A (3g / L) and 100mL silver nitrate solution B (20g / L) respectively, until the solution becomes limpid from turbidity, and Tollens reagent A and B are prepared. Subsequently, in Tollens reagent B, 0.54g sodium hydroxide is added and stirred for 2min, and ammonia solution is continued to be added dropwise until the solution becomes clarification, and the transparent solution obtained is called silver salt solution. 0.1g tartaric acid, 0.8g glucose, 0.5mL ethylenediamine, 6mL ethanol and 0.036g polyethylene glycol 1000 are dissolved in 100mL deionized water, and reduction solution can be obtained.

[0056] The application of degradable rosin-based epoxy foam in electromagnetic materials comprises the following steps:

[0057] (1) The epoxy foam F3 in Example 3 was immersed in an acidic stannous chloride solution, sensitized at room temperature, and then washed with distilled water for 10 minutes to obtain a sensitized degradable rosin-based epoxy foam;

[0058] (2) reacting the sensitized degradable rosin-based epoxy foam in a Tollens A solution at 35° C. for 30 min to obtain a degradable rosin-based epoxy foam modified by a chemical reaction;

[0059] (3) 80 mL of the reducing solution and 20 mL of the silver salt solution were poured into a paper cup and stirred, and the modified degradable rosin-based epoxy foam was placed in the paper cup for silver plating for 1 hour, and then the foam was taken out of the plating solution, washed with water, and vacuum dried to obtain the silver-modified degradable rosin-based epoxy foam F3A. The chemical plating process was repeated 1 to 3 times, and the obtained samples were called degradable rosin-based epoxy foams with conductive properties, namely, silver-modified degradable rosin-based epoxy foams F3A1, F3A2, and F3A3.

[0060] Figure 4 This is the infrared spectrum of the degradable rosin-based epoxy foam prepared in Example 3. The amino group reacts with the epoxy group in TMSEP and EAPA, 909 cm -1 The characteristic absorption peak of the epoxy group disappears, and the 3353cm- -1 The absorption peak at 3431 cm -1 In summary, the propylene diamine latent foaming agent decomposes and the amine group and epoxy group react.

[0061] Figure 5The stress-strain curves of the degradable epoxy foams prepared in Examples 1 to 4 show that as the EAPA content increases, the compressive strength (10% strain) of the foam increases from 0.05 MPa to 1.51 MPa, wherein the maximum compressive strength of the F1 foam reaches 1.75 MPa; the hardness of the foam can be changed by adjusting the molar ratio of EAPA to TMSEP.

[0062] Figure 6 This is the reversible compression performance diagram of the degradable rosin-based epoxy foam F3 prepared in Example 3. During the loading-unloading process, after 60 cycles, the hysteresis loops almost overlap, indicating that the epoxy foam F3 has excellent reversible compressibility.

[0063] Figure 7 This is a schematic diagram of the degradation of the rosin-based epoxy foam prepared in Example 3. 1.8 g of epoxy foam was mixed with 10 wt% aluminum nitrate nonahydrate and 12 g of N,N-dimethylacetamide and heated to 120-140° C. After magnetic stirring for 2 hours, no obvious solid was observed in the mixed solution, indicating that the epoxy foam had been degraded.

[0064] Figure 8 This is the infrared comparison of the rosin-based epoxy foam prepared in Example 3 before and after degradation. The degradation product is 1107 cm -1 The relative peak intensity of the CN stretching vibration peak at 3415cm -1 The peak at shifts to lower wavenumbers, proving that the CN bond is cleaved during the degradation reaction and that NH bonds exist in the degradation products.

[0065] Fig. 9 The electromagnetic shielding effectiveness diagram of the prepared silver-modified degradable rosin-based epoxy foam is as follows. It can be seen from the figure that the electromagnetic shielding effectiveness of the prepared silver-modified degradable rosin-based epoxy foam is 39.27-76.37 dB, that is, the prepared silver-modified degradable rosin-based epoxy foam has excellent electromagnetic shielding performance; among them, the electromagnetic shielding effectiveness of the silver-modified degradable rosin-based epoxy foam prepared by repeating the chemical plating three times in Example 5 reaches 76.37 dB; according to calculation, 99.99999% of electromagnetic waves can be attenuated, meeting the requirements of electronic devices for electromagnetic shielding materials.

[0066] Fig.10 The Joule heating temperature change curve of the prepared silver-modified degradable rosin-based epoxy foam F3A3 driven by a voltage of 0.4-1.0V is shown in Figure 2. Fig.10It can be seen that the surface temperature of the degradable rosin-based epoxy foam having both electromagnetic shielding performance and Joule heating performance reaches a steady-state temperature within 90s when driven by a voltage of 0.4-1.0V; wherein, when driven by a voltage of 1.0V, the steady-state temperature of the silver-modified degradable rosin-based epoxy foam can reach 104.0°C; after the power is cut off, its surface temperature will rapidly drop to the ambient temperature; thus, it can be seen that the silver-modified degradable rosin-based epoxy foam described in the present invention has excellent Joule heating performance, which can alleviate the limitations of cold environments on electronic equipment.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a degradable rosin-based epoxy foam, characterized in that: The following steps are involved: Propylene diamine-based latent foaming agent, propylene diamine, propylene pimaric acid glycidyl ester and 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane are stirred and mixed to obtain a degradable rosin-based epoxy foam; The preparation method of the propylene diamine-based latent foaming agent comprises dissolving propylene diamine in anhydrous ethanol at room temperature, introducing carbon dioxide gas to react for 2 to 4 hours, and obtaining the propylene diamine-based latent foaming agent; The preparation method of acrylpimaric acid glycidyl ester comprises reacting acrylpimaric acid, epichlorohydrin and benzyltriethylammonium chloride at 110-117° C. for 3-5 hours, then cooling to 50-60° C., adding sodium hydroxide and continuing the reaction at 50-60° C. for 4-6 hours to obtain acrylpimaric acid glycidyl ester.

2. The method for preparing the degradable rosin-based epoxy foam according to claim 1, characterized in that: The mass ratio of the propylene diamine-based latent foaming agent, propylene diamine, propylene pimaric acid glycidyl ester and 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane is (0.1-0.3):1:(5-11):(3-7).

3. The method for preparing the degradable rosin-based epoxy foam according to claim 1 or 2, characterized in that: The reaction conditions described in step (1) are: maintaining at a temperature of 50 to 70° C. for 20 to 40 minutes, and then curing at a temperature of 120 to 160° C. for 1 to 4 hours.

4. The method for preparing the degradable rosin-based epoxy foam according to claim 1, characterized in that: The mass ratio of acrylpimaric acid, epichlorohydrin, benzyltriethylammonium chloride and sodium hydroxide is (80-90):(400-410):1:(15-20).

5. A degradable rosin-based epoxy foam prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the degradable rosin-based epoxy foam prepared by the method for preparing the degradable rosin-based epoxy foam according to any one of claims 1 to 4 or the degradable rosin-based epoxy foam according to claim 5 in electromagnetic materials.

7. The use of the degradable rosin-based epoxy foam in electromagnetic materials according to claim 6, characterized in that: The application method includes the following steps: (1) immersing the degradable rosin-based epoxy foam in an acidic stannous chloride solution, sensitizing it at room temperature, and then washing it with deionized water for 10 to 30 minutes to obtain a sensitized degradable rosin-based epoxy foam; (2) reacting the sensitized degradable rosin-based epoxy foam in a Tollens A solution for 0.5 to 1.5 hours to obtain a degradable rosin-based epoxy foam modified by a chemical reaction; (3) Plating the modified degradable rosin-based epoxy foam in a mixture of a reducing solution and a silver salt solution for chemical plating for 1 to 2 hours, and after drying, repeating the process 1 to 3 times to obtain a degradable rosin-based epoxy foam with conductive properties.

8. The method for preparing the degradable rosin-based epoxy foam according to claim 7, characterized in that: The preparation method of the acidic stannous chloride solution is to dissolve stannous chloride dihydrate in a dilute hydrochloric acid solution to obtain the acidic stannous chloride solution; The preparation method of the silver salt solution is as follows: sodium hydroxide is added to Tollens B solution and stirred, and then an ammonia solution is continuously added dropwise until the solution becomes clear, and the obtained transparent solution is the silver salt solution.

9. The method for preparing the degradable rosin-based epoxy foam according to claim 8, characterized in that: The preparation method of the Tollens A and Tollens B solutions is to add an ammonia solution to a 3-5 g / L silver nitrate solution A and a 10-20 g / L silver nitrate solution B, respectively, until the solution changes from turbid to clear, to obtain a Tollens A and a Tollens B solution, respectively; The reducing solution is prepared by dissolving tartaric acid, glucose, ethylenediamine, ethanol and polyethylene glycol in deionized water to obtain the reducing solution.

10. The method for preparing the degradable rosin-based epoxy foam according to claim 9, characterized in that: The mass ratio of the tartaric acid, glucose, ethylenediamine, ethanol and polyethylene glycol is 1:(8-10):(3-5):(45-50):(0.2-0.5).

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