A low-dielectric high-strength phosphate-based polymer and a preparation method thereof

Abstract

The application discloses a kind of low dielectric high-strength phosphate-based geopolymer and preparation method thereof.The preparation method includes the following steps: (1) acid activator pretreatment: phosphoric acid solution is mixed with water to carry out ion balance treatment, and fully ionized pre-equilibrium acid activator is obtained;(2) mixed pulping: siliceous raw material is mixed with the pre-equilibrium acid activator, the molar ratio of P / Al is controlled to be 0.6-1.2, and uniform geopolymer slurry is obtained by stirring;(3) forming and curing: the slurry is cast into shape and cured, and an Al-O-P covalent bond dominated network skeleton is constructed to obtain a green geopolymer;(4) dehydration treatment: the green geopolymer is subjected to dehydration treatment.The application effectively solves the problems of high loss, easy moisture absorption and mutual exclusion of strength and dielectric properties of inorganic cementing materials at high frequency, and is suitable for 5G / 6G high-frequency communication, radar wave-transparent, electronic packaging and intelligent building fields.

Description

Technical Field

[0001] This invention relates to structural materials with low dielectric constants, and particularly to a low dielectric high-strength phosphate-based polymer and its preparation method. Background Technology

[0002] With the rapid development of 5G and 6G communications, high-frequency circuit boards, electronic packaging, and aerospace technologies, electronic components and electromagnetic windows place stringent requirements on the dielectric properties of packaging and structural materials. In the MHz to GHz high-frequency band, materials not only need extremely low dielectric constants (ε′) to reduce signal delay, but also extremely low dielectric losses (tanδ) to avoid heat generation and signal attenuation caused by energy dissipation. Furthermore, materials must also possess excellent mechanical strength and environmental stability. Traditional silicate cement-based materials, due to the presence of large amounts of chemically bound water, physically adsorbed water, and free metal ions, exhibit severe dipole relaxation losses and conductivity losses under electromagnetic fields, leading to significant signal attenuation. Geopolymers, as a novel inorganic cementitious material, have attracted attention due to their excellent mechanical properties and thermal stability. However, conventional alkali-activated geopolymers still require alkali metal ions (such as Na⁺ and K⁺) to balance the negative charge of the aluminum-oxygen tetrahedra ([AlO4]⁻) in the silicon-aluminum network. These free ions undergo long-range migration under alternating electric fields, resulting in significant conductivity losses, which are difficult to meet the needs of high-performance electronics and electromagnetic protection fields.

[0003] Phosphate-based polymers have significant potential in reducing electrical conductivity loss, but existing technologies often achieve low dielectric constants by simply increasing porosity, which often comes at the cost of mechanical strength, making it difficult to achieve synergistic optimization of structural strength and electrical performance.

[0004] Furthermore, phosphate-based polymers with low dielectric constants still face the following key challenges in practical preparation and application:

[0005] (1) Reaction kinetics runaway: The acid-base reaction between the strong acid activator and the silicon-aluminum raw material is extremely violent, and the heat release is concentrated and rapid, which can easily lead to thermal stress microcracks and structural inhomogeneity in the matrix, seriously damaging the mechanical strength and dielectric properties.

[0006] (2) Polarization loss caused by bound water: The formation of phosphate geopolymers involves complex water exchange, and traditional oven drying processes cannot completely remove bound water that is bonded to the inorganic network by hydrogen bonds. The dipole relaxation generated by these residual water molecules in the GHz high-frequency band is the main reason for the excessive dielectric loss.

[0007] (3) Performance fluctuations caused by hygroscopicity: Inorganic geopolymer networks have natural hydrophilicity and are prone to absorbing moisture from the air in humid environments, causing the dielectric constant and loss to fluctuate drastically with the ambient humidity, which cannot meet the stability requirements for long-term service of electronic components. Summary of the Invention

[0008] To address the technical problems of high dielectric loss in existing geopolymer materials at high frequencies (MHz-GHz) and the drastic decrease in mechanical strength caused by reducing the dielectric constant through increased porosity, this invention precisely controls the P / Al molar ratio and initiates the reaction after the acid activator reaches dynamic ionization equilibrium, thereby promoting [PO4]. + With [AlO4] - The tetrahedral structure forms stable alternating covalent bonds, enabling extremely low electrical conductivity loss in addition to the long-range migration of free ions under an alternating electric field, while maintaining excellent mechanical strength. In some preferred embodiments of the present invention, by optimizing the microporous structure and deep moisture content, a cementitious material with ultra-low dielectric loss, high environmental stability, and excellent mechanical strength in the frequency range of 1 MHz to 10 GHz is prepared. This material is particularly suitable for wave-transparent components in high-frequency communication and electronic packaging.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] This invention provides a method for preparing a low-dielectric-strength phosphate-based polymer, comprising the following steps:

[0011] (1) Pretreatment of acid activator: Phosphoric acid solution is mixed with water and subjected to ionization equilibrium treatment to obtain pre-equilibrium acid activator;

[0012] (2) Mixing and pulping: The silica-alumina raw material is mixed with the pre-balanced acid activator, and the P / Al molar ratio is controlled to be 0.6-1.2. The mixture is stirred to obtain a uniform geopolymer slurry.

[0013] (3) Molding and curing: The slurry is cast and cured to construct a network framework dominated by Al-OP covalent bonds, and a geopolymer green body is obtained;

[0014] (4) Dehydration treatment: Deep dehydration treatment is performed on the geopolymer green body.

[0015] Furthermore, the deep dehydration treatment includes the following specific steps:

[0016] (1) Vacuum freeze-drying treatment: Under the conditions of vacuum degree ≤ 10 Pa and cold trap temperature ≤ -30℃, the free water inside the material is sublimated and removed;

[0017] (2) Intermittent microwave drying treatment: Intermittent heating treatment is carried out using microwaves with a power of 200-600 W until the sample mass reaches a constant value. The residual bound water bound to the inorganic network hydrogen bonds is completely removed by utilizing the selective heating effect of microwaves.

[0018] Furthermore, the low-dielectric-strength phosphate-based polymer contains [AlO4] internally. - and [PO4] + The material has an amorphous three-dimensional network gel structure composed of tetrahedrons connected by alternating covalent bonds, and has uniformly distributed closed micropores with a diameter of less than 100 μm inside; the material has a dielectric constant ε′ < 5.0, a dielectric loss tanδ ≤ 0.005, and a compressive strength ≥ 50 MPa in the frequency range of 1 MHz to 10 GHz.

[0019] Further, the ionization equilibrium treatment in step (1) takes 12-48 hours (preferably 18-30 hours), and the criterion is that the pH value and conductivity fluctuation of the acid activator are both less than 5% under constant temperature conditions. The fluctuation is obtained by three consecutive sampling measurements, and the interval between adjacent samplings is not less than 2 hours.

[0020] Furthermore, the aluminosilicate raw material is selected from one or more of metakaolin, fly ash, granulated blast furnace slag, coal gangue, or aluminosilicate minerals; preferably, the aluminosilicate raw material is metakaolin.

[0021] Further, in step (2), the water-to-solid ratio is controlled to be 0.15-0.35; the specific curing method in step (3) is gradient curing: first, pre-curing at 20-25℃ for 24 hours to build a preliminary gel skeleton, and then adjusting to 40-80℃ for constant temperature heat curing for 12-36 hours to promote polycondensation reaction.

[0022] Furthermore, in step (2), a hydrophobic modifier is added to the slurry. The hydrophobic modifier is a mixture of organosilicon polymer and silane coupling agent in a mass ratio of 10-50:1, and the amount added is 0.5%-2.0% of the mass of the aluminosilicate raw material.

[0023] Furthermore, the organosilicon polymer is selected from one or more of polysiloxanes, modified silicone oils, or organosilicon resins. Preferably, the organosilicon polymer is hydroxyl-terminated polydimethylsiloxane (PDMS) or polymethylphenylsiloxane. The silane coupling agent is selected from one or more of aminosilanes, epoxysilanes, alkylsilanes, or vinylsilanes. Preferably, the silane coupling agent is KH-550, KH-560, n-octyltriethoxysilane, or epoxypropyltrimethoxysilane.

[0024] Furthermore, in step (2), a nonionic surfactant is added to the slurry as an air-entraining agent, with an addition amount of 0.01%-0.03% of the mass of the silica-alumina raw material. The air-entraining agent is preferably isooctylphenyl polyoxyethylene ether (Triton X-100).

[0025] Further, in step (2), the pulping process is as follows: while mechanically stirring, an ultrasonic field is applied to perform cavitation and refinement treatment, wherein the ultrasonic power is 200-400W and the ultrasonic frequency is 20-40KHz, which is used to construct microbubbles in the slurry to form closed micropores with a diameter of less than 100μm inside the hardened material.

[0026] The present invention also provides a low-dielectric-strength phosphate-based polymer, which is prepared by the preparation method of the low-dielectric-strength phosphate-based polymer; the low-dielectric-strength phosphate-based polymer can be used as a wave-transparent material.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) Achieving intrinsic charge balance eliminates ion migration loss at the source.

[0029] By precisely controlling the P / Al molar ratio and initiating the reaction after the acid activator reaches dynamic ionization equilibrium, [PO4] is promoted. + With [AlO4] - Tetrahedrons form stable alternating covalent bonds. This intrinsic charge balance mechanism replaces the traditional base-excited system's reliance on alkali metal ions (Na+). + K + The balanced charge mode eliminates the long-range migration of free ions under alternating electric fields, resulting in extremely low electrical conductivity loss in the material.

[0030] (2) Staged dehydration eliminates high-frequency dipole relaxation loss

[0031] This invention introduces for the first time a synergistic process of vacuum freeze-drying and intermittent microwave drying. Freeze-drying efficiently removes free water while maintaining the stability of the gel structure; microwave drying selectively removes bound water bound to network hydrogen bonds by utilizing the polar molecular response characteristics. The hierarchical synergistic effect of the two processes fundamentally eliminates the dipole relaxation loss caused by moisture in the GHz high-frequency band, enabling the material to maintain ultra-low and stable dielectric properties over a wide frequency range.

[0032] (3) Synergistic optimization of microstructure and mechanical properties

[0033] This invention departs from the traditional single-mode approach of reducing dielectric constant by increasing porosity. Instead, it constructs closed, uniform micropores with a diameter of less than 100 μm in a dense matrix using ultrasonic cavitation-assisted methods. This controlled closed micropore structure significantly reduces the dielectric constant while effectively avoiding stress concentration and maintaining the material's high strength (≥ 50 MPa), achieving an integrated structure-function design.

[0034] (4) Chemical anchoring of hydrophobic layers enhances the environmental stability of materials

[0035] By introducing a hydrophobic modifier with chemical anchoring effect during the mixing process, a stable waterproof barrier is formed on the gel pore wall, which significantly reduces the material's moisture sensitivity and effectively prevents secondary intrusion of moisture in the service environment, thus solving the bottleneck problem of the degradation of dielectric properties of geopolymers due to moisture absorption.

[0036] (5) Significantly improved process stability

[0037] The pre-equilibrium treatment of the acid activator effectively slowed down the violent exothermic reaction of strong acid with silicon-aluminum raw materials in the early stage. Combined with the gradient curing system, it solved the common defects of expansion, cracking and structural inhomogeneity of phosphate-based polymers from both kinetic and thermodynamic dimensions, ensuring the consistency and repeatability of product quality in large-scale production. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the preparation process of a low-dielectric, high-strength phosphate-based polymer according to an embodiment of the present invention.

[0039] Figure 2 The images show the microstructure of the low dielectric high strength phosphate-based polymers according to embodiments of the present invention; wherein: (a) Example 4 (P / Al=0.6); (b) Example 2 (P / Al=0.8); (c) Example 1 (P / Al=1.0); (d) Example 3 (P / Al=1.2).

[0040] Figure 3 Infrared spectra of the low dielectric high strength phosphate-based polymer of the present invention and the phosphate-based polymer of Comparative Example 1 are shown; wherein: (a) Examples 1-4; (b) Comparative Example 1. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of protection of the invention.

[0042] The overall process flow for preparing the low-dielectric-strength phosphate-based polymer of the present invention is as follows: Figure 1 As shown, the core logic of this process lies in regulating the reaction kinetics through the pre-equilibrium ionization of the acid activator, optimizing the gel network and microporous structure through ultrasonic assistance and modification, and completely eliminating the interference of moisture on dielectric properties through a graded synergistic dehydration process. The material prepared in this embodiment is particularly suitable for wave-transparent components in the field of high-frequency communication and electronic packaging.

[0043] The following raw materials are used in the following embodiments:

[0044] Silicon-aluminum source: A silicon-aluminum raw material is selected. In the following examples, metakaolin with a density of 2.62 g / cm³ and a characteristic particle size D is preferred. 50 It is approximately 11.57 μm.

[0045] Activator: Industrial grade phosphoric acid solution, with a mass percentage concentration of 85%.

[0046] Hydrophobic modifiers: polydimethylsiloxane (PDMS), silane coupling agent (KH-550)

[0047] Air-entraining agent: a nonionic surfactant, preferably isooctylphenyl polyoxyethylene ether (Triton X-100) in the following examples.

[0048] The technical solution and performance of the present invention will be further verified and explained below with reference to specific embodiments and comparative examples.

[0049] Example 1: Optimal process group (P / Al = 1.0)

[0050] (1) Pre-equilibrium ionization treatment of acid activator: 101.82 g of phosphoric acid and 14.73 g of deionized water were weighed and mixed according to the requirements of P / Al molar ratio of 1.0 and water-to-solid ratio of 0.30. The mixture was stirred at 200 rpm for 8 min at 25 °C and then sealed and allowed to stand. During the standing period, the pH value and conductivity of the solution were tested every 2 h. After standing for 24 h, three consecutive sampling tests showed that the fluctuation rate of pH value and conductivity was less than 3% (meeting the judgment standard of less than 5%), and a fully ionized pre-equilibrium acid activator was obtained.

[0051] (2) Mixing and pulping and composition control: Add the above activator to 100g of metakaolin. At the same time, add 1g of PDMS and 0.04g of KH-550 (the mass ratio of the two is 25:1, and the total amount of composite hydrophobic agent accounts for 1.0% of the powder mass) and 0.02g of Triton X-100 (the amount is 0.02%).

[0052] (3) Ultrasonic-assisted pulping: The mixture was placed in a CNC ultrasonic disperser, and the ultrasonic power was set to 300W and the frequency to 40KHz. The mixture was mechanically stirred (600rpm) for 6 minutes. The cavitation effect of the ultrasonic waves was used to form a large number of uniform microbubbles with a diameter of less than 100μm in the slurry and to promote the depolymerization of silicon and aluminum monomers.

[0053] (4) Gradient curing molding: After the slurry is poured and molded, it is sealed and pre-cured at 25℃ for 24h to build a preliminary gel skeleton. Then it is transferred to an oven and cured at 60℃ for 24h to obtain geopolymer green body.

[0054] (5) Graded deep dehydration treatment: After the green body is demolded, it is first subjected to vacuum freeze drying (-80℃, vacuum degree 5Pa) for 24h to remove free water by sublimation; then it is subjected to intermittent microwave synergistic drying (power 300W, working for 30s / stopping for 60s cycle) until the quality is constant (quality change rate < 1%) to remove bound water.

[0055] Results: The microstructure of the sample is shown in Figure 2(c). It can be clearly observed that, at the optimal P / Al ratio of 1.0, a continuous and dense gel phase was formed, with uniformly distributed closed micropores less than 100 μm in diameter. Infrared spectroscopy characterization (see Figure 3(a)) revealed a significant Al-OP stretching vibration peak near 930 cm⁻¹, with the peak position shifting towards lower wavenumbers, confirming the construction of a dense covalent network and the intrinsic charge self-balancing state. Compared to Comparative Example 1, which only used oven drying, the process of this invention significantly eliminated residual moisture, reducing the loss to below 0.005.

[0056] Example 2: Preparation of low-dielectric-strength phosphate-based polymer (P / Al = 0.8)

[0057] (1) Activator treatment: Weigh 81.46g of phosphoric acid and 17.78g of deionized water according to the requirements of P / Al molar ratio of 0.8 and water-solid ratio of 0.30. Stir at 25℃ and let stand for 24h to reach ionization equilibrium.

[0058] (2) Pulping and modification: Add the above activator to 100g of metakaolin, and add 1.0% by mass of PDMS / KH-550 composite hydrophobic agent and 0.02% of Triton X-100.

[0059] (3) Ultrasonic pulping: Ultrasonic power of 300W is used for auxiliary dispersion, mechanical stirring speed is 600rpm, and pulping time is 6min.

[0060] (4) Gradient curing and dehydration: The process steps are the same as in Example 1.

[0061] Results: The microstructure of the sample is as follows Figure 2 As shown in (b), this indicates a high degree of reactivity and a relatively dense structure; the infrared spectral results (see...) Figure 3 (a) shows that phosphoric acid and metakaolin undergo a polymerization reaction, but due to the charge self-balancing being slightly inferior to that in Example 1, the dielectric loss increases slightly to 0.0035.

[0062] Example 3: Preparation of low-dielectric-strength phosphate-based polymer (P / Al = 1.2)

[0063] (1) Activator treatment: Weigh 122.18g of phosphoric acid and 11.67g of deionized water according to the requirements of P / Al molar ratio of 1.2 and water-solid ratio of 0.30. Stir at 25℃ and let stand for 24h.

[0064] (2) Pulping and modification: Add the above-mentioned activator to 100g of metakaolin. The modifier components and addition amount are the same as in Example 1.

[0065] (3) Ultrasonic pulping, gradient curing and dewatering: The process steps are the same as in Example 1.

[0066] Results: Both dielectric constant and loss increased. This is due to the excessive introduction of free carriers by phosphate groups, leading to an increase in the content of dipole groups (see...). Figure 3 In (a)), and excessive phosphoric acid leads to the formation of localized phosphoric acid enrichment phases (such as...). Figure 2 (as shown in d).

[0067] Example 4: Control group with P / Al molar ratio at the lower limit (P / Al = 0.6, water-to-solid ratio = 0.25)

[0068] (1) Activator treatment: Weigh 61.09g of phosphoric acid and 20.84g of deionized water according to the requirements of P / Al molar ratio of 0.6 and water-solid ratio of 0.25. Stir at 25℃ and let stand for 24h.

[0069] (2) Pulping, curing and dewatering: The process steps are the same as in Example 1, except that the ultrasonic power is adjusted to 400W to meet the air entrainment requirements of the higher viscosity slurry.

[0070] Results: The morphology of the obtained samples is shown in Figure 2(a), and the infrared spectral results are shown in Figure 3(a). Analysis shows that due to insufficient phosphoric acid, the reaction degree is low, and the matrix exhibits obvious particle accumulation and through cracks. This leads to a significant decrease in the mechanical strength of this group (only 58.5 MPa) and an increase in dielectric loss.

[0071] Comparative Example 1: Drying was performed using a conventional oven (105℃, 24h).

[0072] (1) Preparation process: The initial steps (P / Al=1.0, pulping, modification, curing) are exactly the same as in Example 1.

[0073] (2) Drying difference: Vacuum freeze drying and microwave drying are not performed; only traditional 105℃ oven drying is used for 24 hours.

[0074] Results: The dielectric loss was as high as 0.1200. Analysis suggests that traditional drying methods cannot remove weakly bound water, and the water undergoes severe dipole relaxation at GHz.

[0075] Comparative Example 2: Unhydrophobic Modification Group

[0076] (1) Preparation process: The process is exactly the same as in Example 1.

[0077] (2) Modification difference: No PDMS and KH-550 composite hydrophobic agent are added during the pulping process.

[0078] Results: Initial performance was acceptable, but after being placed in an environment with 85% humidity for 7 days, the loss increased sharply to over 0.05.

[0079] Comparative Example 3: No ultrasonic / air evacuation process

[0080] (1) Preparation process: The process is exactly the same as in Example 1.

[0081] (2) Differences: Conventional mechanical stirring was used without adding Triton X-100 surfactant and ultrasonic dispersion was not activated.

[0082] Results: The sample exhibits a dense, non-porous structure with a dielectric constant as high as 9.8 and a significant decrease in transmittance.

[0083] Table 1 Performance test results of each embodiment and comparative example

[0084]

[0085] Note: All test data above are obtained by taking the maximum value within the 1 MHz - 10 GHz frequency band.

[0086] Performance Results Analysis and Mechanism Discussion

[0087] (1) The influence of intrinsic charge balance mechanism

[0088] Combination Figure 2 and Figure 3Analysis shows that the material exhibits optimal dielectric properties when the P / Al molar ratio is in the range of 0.8-1.0. This is because, at this ratio, the [AlO4]⁻ and [PO4]⁺ tetrahedra are most fully developed and exhibit alternating covalent connections. As shown in Example 1, the reaction rate was slowed down by the pre-equilibrium treatment with an acid activator, resulting in a continuous and dense network within the matrix (see Figure 2(c)). When P / Al = 1.0, the degree of electroneutrality is highest, internal charge carriers are effectively bound, and electrical conduction losses are minimized. In contrast, Example 4 (P / Al = 0.6) resulted in a loose network development due to insufficient phosphoric acid (see Figure 2(a)), leading to numerous cracks and interfaces, which enhanced interfacial polarization losses.

[0089] (2) Suppression of high-frequency loss by staged deep dehydration

[0090] Comparing Example 1 with Comparative Example 1, it was found that the dielectric loss of the sample dried using only a conventional 105°C oven was as high as 0.1200. Analysis suggests that conventional drying cannot remove bound water bonded to the inorganic network by hydrogen bonds. This invention removes free water through vacuum freeze-drying, combined with the selective heating effect of microwaves to precisely "target" and remove bound water. FTIR spectroscopy shows (see Figure 3(b)) that Example 1 showed a dielectric loss of 0.1200 at 3398 cm⁻¹. -1 and 1655 cm -1 The hydroxyl vibration peak at the point was significantly weakened, which proved the elimination of bound water, thereby eliminating the high-frequency dipole relaxation loss.

[0091] (3) Loss reduction effect of controlled microporous structure

[0092] Comparative Example 3, while exhibiting the highest strength, also had a dielectric constant as high as 9.8. Example 1 introduced closed, uniform micropores with a diameter of less than 100 μm through ultrasonic-assisted cavitation (see Figure 2(c)). While ensuring the continuity and high strength of the matrix, an air phase (ε ≈ 1.0) was successfully introduced, significantly reducing the overall dielectric constant and improving impedance matching, thereby increasing the transmittance from 45% to 76%.

[0093] (4) Environmental stability verification of chemically anchored hydrophobic layer

[0094] Both Example 1 and Comparative Example 2 were placed in an environment with 85% humidity for 7 days. The loss of Example 1 remained below 0.002, while that of Comparative Example 2, due to the lack of chemical anchoring protection from PDMS, increased sharply to over 0.05 due to the absorption of moisture from the air. This confirms that the "nanoscale waterproof barrier" formed by the hydrophobic modifier on the pore walls is crucial for maintaining the long-term service performance of the material.

[0095] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a low-dielectric-strength phosphate-based polymer, characterized in that, Includes the following steps: (1) Pretreatment of acid activator: The phosphoric acid solution is mixed with water and subjected to ionization equilibrium treatment to obtain a fully ionized pre-equilibrium acid activator; (2) Mixing and pulping: The silica-alumina raw material is mixed with the pre-balanced acid activator, and the P / Al molar ratio is controlled to be 0.6-1.

2. The mixture is stirred to obtain a uniform geopolymer slurry. (3) Molding and curing: The slurry is cast and cured to construct a network framework dominated by Al-OP covalent bonds, and a geopolymer green body is obtained; (4) Dehydration treatment: Dehydration treatment is performed on the geopolymer green body.

2. The method for preparing the low-dielectric-strength, high-strength phosphate-based polymer according to claim 1, characterized in that, The network skeleton is composed of [AlO4]. - and [PO4] + An amorphous three-dimensional network gel structure composed of tetrahedrons connected by alternating covalent bonds.

3. The method for preparing the low-dielectric-strength phosphate-based polymer according to claim 1, characterized in that, The dehydration process described in step (4) is as follows: (41) Vacuum freeze drying: vacuum degree ≤ 10 Pa, cold trap temperature ≤ -30℃, so that free water sublimates; (42) Intermittent microwave drying treatment: microwave power is 200-600 W, and the sample mass is treated until it is constant in order to remove bound water.

4. The method for preparing the low-dielectric-strength phosphate-based polymer according to claim 1, characterized in that, In step (2), a hydrophobic modifier is added to the geopolymer slurry and stirred. The hydrophobic modifier is a mixture of organosilicon polymer and silane coupling agent at a mass ratio of 10-50:1, and the dosage is 0.5%-2.0% of the mass of the aluminosilicate raw material. In step (2), a nonionic surfactant is also added to the geopolymer slurry, and the dosage is 0.01%-0.03% of the mass of the aluminosilicate raw material.

5. The method for preparing the low-dielectric-strength phosphate-based polymer according to claim 4, characterized in that, The organosilicon polymer is at least one of polysiloxane, modified silicone oil, or organosilicon resin; the silane coupling agent is at least one of aminosilane, epoxysilane, alkylsilane, or vinylsilane.

6. The method for preparing the low-dielectric-strength phosphate-based polymer according to claim 1, characterized in that, In step (2), an ultrasonic-assisted slurry preparation step is also performed, specifically: an ultrasonic field is applied to the geopolymer slurry for cavitation and refinement treatment, wherein the ultrasonic power is 200-400W and the ultrasonic frequency is 20-40KHz, which is used to construct microbubbles in the slurry to form closed micropores with a diameter of less than 100μm inside the hardened material.

7. The method for preparing the low-dielectric-strength phosphate-based polymer according to claim 1, characterized in that, The silicoaluminate raw material is selected from at least one of metakaolin, fly ash, granulated blast furnace slag, coal gangue, or aluminosilicate minerals.

8. The method for preparing the low-dielectric-strength phosphate-based polymer according to claim 1, characterized in that, The ionization equilibrium treatment in step (1) takes 12-48 hours. The criterion is that the pH value and conductivity fluctuation of the acid activator are both less than 5% under constant temperature conditions.

9. The method for preparing the low-dielectric-strength phosphate-based polymer according to claim 1, characterized in that, In step (2), the water-to-solid ratio is controlled to be 0.15-0.35; the specific curing method in step (3) is gradient curing: first, pre-curing at 20-25℃ for 24 hours, and then adjusting to 40-80℃ for constant temperature curing for 12-36 hours.

10. A low-dielectric-strength, high-strength phosphate-based polymer, characterized in that, The low-dielectric high-strength phosphate-based polymer is prepared by the preparation method of any one of claims 1 to 9; the low-dielectric high-strength phosphate-based polymer is used as a wave-transparent material.

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