Modification method of hydrolysis-resistant EMAA-Na < + > copolymer for laminated glass

Abstract

The invention relates to the technical field of high polymer materials, and discloses a modification method of an anti-hydrolysis EMAA-Na < + > copolymer for laminated glass, which is characterized in that sodium methacrylate (Na < + > MAA) in the EMAA-Na < + > copolymer is catalyzed by a metal catalyst to be converted into methacrylic acid (MAA) in an acidic system, and after post-treatment, the hydrolysis-resistant EMAA-Na < + > copolymer is obtained. The hydrolysis-resistant EMAA-Na < + > copolymer for the laminated glass is obtained. The ethylene-methacrylic acid-sodium methacrylate (EMAA-Na < + >) copolymer is modified, so that the ethylene-methacrylic acid-sodium methacrylate (EMAA-Na < + >) copolymer has remarkable hydrolysis resistance, and the physical, chemical and optical properties of the material are comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a modification method of a hydrolysis-resistant EMAA-Na copolymer for laminated glass. + Background Art

[0002] In modern architecture and the automotive industry, laminated glass has gradually become an indispensable material due to its high safety and excellent optical properties. In these applications, PVB (polyvinyl butyral) and SGP (ethylene-sodium methacrylate copolymer) are the most common interlayer materials.

[0003] Ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, as a variant of SGP material, has excellent bonding properties, mechanical properties and weather resistance. Due to its unique ionic structure, while providing strong bonding, it can provide stronger bonding force and more excellent impact resistance than PVB. Therefore, EMAA-Na + is considered to be one of the ideal choices for future laminated glass interlayer materials.

[0004] However, the application of EMAA-Na + still faces a key problem: poor hydrolysis stability. The sodium methacrylate (Na + MAA) groups in EMAA-Na + are prone to react with water molecules in a humid environment, resulting in changes in the chemical structure of the material, hydrolysis to generate carboxylic acid groups, and a significant decrease in the bonding force of the material. This hydrolysis not only affects the bonding performance of the material, but may also lead to a decrease in the mechanical strength and optical properties of the material, increasing the safety risk during the use of laminated glass. Especially under conditions of high humidity, strong temperature fluctuations and ultraviolet irradiation, this hydrolysis problem is particularly serious, resulting in EMAA-Na + not performing as expected in some application scenarios.

[0005] Traditionally, in order to improve the hydrolysis resistance of EMAA-Na + materials, surface coating or incorporation of hydrolysis-resistant additives are mainly used. However, these methods have many limitations. For example, the coating is prone to peeling off after long-term use, affecting the overall performance of the material, and the introduction of additives often leads to a decrease in the transparency and mechanical properties of the material. In addition, surface treatment technologies also face problems such as complex processes and high costs. Therefore, how to start from the material itself, improve the molecular structure of EMAA-Na + and enhance its hydrolysis resistance has become a technical problem that urgently needs to be solved.

[0006] To solve this problem, the present application proposes to modify the EMAA-Na + material to improve its hydrolysis resistance and ensure that the material can still maintain good mechanical and optical properties in harsh environments. Summary of the Invention

[0007] The hydrolysis problem of traditional EMAA-Na + material mainly stems from the sodium methacrylate (Na + MAA) group in its chemical structure. Na + MAA is formed by copolymerizing sodium methacrylate with vinyl through a free radical polymerization reaction. This group has good ionic bond characteristics, enabling EMAA-Na + to exhibit excellent performance in bonding with polar materials such as glass. However, the bond between the sodium ion and the carboxylate ion in the Na + MAA group is relatively weak. Especially in a humid environment, water molecules will undergo an ion exchange reaction with the sodium ion, causing the sodium ion to detach from the matrix. The carboxylate ion will further undergo a hydrolysis reaction with water to generate methacrylic acid and sodium hydroxide. This reaction not only destroys the ionic bond structure in the material but also causes a change in the pH value of the material due to the generated sodium hydroxide, further exacerbating the hydrolysis reaction. Therefore, when the EMAA-Na + material is exposed to moisture and water environment for a long time, the chemical stability of the material will significantly decrease, resulting in performance degradation. To solve this problem, the present invention provides a method for modifying a hydrolysis-resistant EMAA-Na + copolymer for laminated glass. By reducing the sodium methacrylate group in EMAA-Na + to methacrylic acid, the content of easily hydrolyzable groups in the material is reduced, fundamentally improving the hydrolysis resistance of the material. At the same time, the present invention ensures the efficiency and stability of the modification process through process steps such as liquid nitrogen pulverization, hydrochloric acid reduction, buffer solution regulation, and catalyst assistance, avoiding the limitations of complex coating and additive modification in the prior art. In addition, the modified EMAA-Na + material not only retains its original excellent adhesion and mechanical properties but also has higher transparency and durability, and is particularly suitable as an interlayer film material for laminated glass.

[0008] To achieve the above object, the present invention adopts the following technical solution: A method for modifying a hydrolysis-resistant EMAA-Na + copolymer for laminated glass. Under an acidic system, the sodium methacrylate (Na + in the EMAA-Na +Convert maleic anhydride (MAA) to methacrylic acid (MAA), and through post-treatment, obtain hydrolysis-resistant EMAA-Na for laminated glass + Copolymer.

[0009] Preferably, the EMAA-Na + Copolymer also includes a pre-treatment step before the catalytic reaction. The pre-treatment step is to freeze it with liquid nitrogen and then crush it to a particle size of 10-50 microns.

[0010] Preferably, the acidic system is prepared using any one or several of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, hydrobromic acid, and acetic acid.

[0011] Preferably, under the acidic system, the pH of the system is adjusted to 3.5-4 by a buffer solution.

[0012] Preferably, the buffer solution is phosphate buffer or Tris buffer.

[0013] Preferably, the metal catalyst is selected from any one or several of zinc chloride, iron chloride, copper chloride, aluminum chloride, aluminum oxide, zirconium oxide, and titanium oxide.

[0014] Preferably, the method of post-treatment is: after the reaction, use sodium bicarbonate solution to neutralize the remaining acid, wash the product with deionized water to remove by-products, and vacuum freeze-dry to obtain hydrolysis-resistant EMAA-Na + Material.

[0015] Preferably, the acidic system is prepared with 1.5 M hydrochloric acid solution, the pH of the system is adjusted to 3.5-4 by phosphate buffer, and boiled at 80-120 °C for 1-5 hours.

[0016] Preferably, the mass-volume ratio of the EMAA-Na + Copolymer to 1.5 M hydrochloric acid is 30-60 g: 150-250 ml.

[0017] Preferably, the dosage of the metal catalyst is 0.5%-1% of the total mass of the solution.

[0018] Compared with the prior art, the beneficial effects of the present invention are: The present invention modifies the ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, enabling it to have remarkable hydrolysis resistance and comprehensively improving the physical, chemical, and optical properties of the material. Compared with the existing hydrolysis-resistant technologies, the present invention has the following outstanding advantages: 1. Greatly improved hydrolysis resistance Traditional EMAA-Na +The material is prone to hydrolysis in a humid environment, especially the sodium methacrylate group (Na + MAA) in it is easy to react with water molecules to form carboxylic acid, resulting in a decline in the material's performance. Through a chemical reduction method, the present invention reduces the Na + MAA group to methacrylic acid (MAA), significantly reducing the hydrolysis-sensitive groups in the material and fundamentally improving the hydrolysis resistance of the material. After this modification, the EMAA-Na + material can still maintain excellent chemical stability even under high humidity and high temperature conditions, without obvious hydrolysis phenomenon. This enables the modified material to maintain its performance stability in extreme climate conditions, such as environments with high humidity, strong ultraviolet radiation, and large temperature fluctuations. Especially in the fields of construction and automotive, laminated glass is usually exposed to humid environments, such as coastal areas and climates with frequent rain and snow. The improvement of hydrolysis resistance greatly extends the service life of the glass and reduces the safety hazards caused by material hydrolysis.

[0019] 2. Maintain excellent adhesion and mechanical properties The present invention not only improves the hydrolysis resistance of the EMAA-Na + material through chemical reduction modification, but also ensures excellent performance of the material in terms of adhesion and mechanical properties. By optimizing the chemical composition and structure in the material, the modified EMAA-Na + material can still form a strong bond with substrates such as glass and metal, and the bonding performance will not decline due to hydrolysis. After testing, the bonding strength of the modified material can reach 30 - 45 N / cm², meeting the requirements of high-performance laminated glass.

[0020] In addition, through the liquid nitrogen pulverization technology, the present invention controls the particle size of the EMAA-Na + powder between 10 - 50 microns, increasing the specific surface area of the material and ensuring the uniformity and sufficiency of the reduction reaction. While maintaining the material structure, it further improves the tensile strength and toughness of the material. The tensile strength of the modified material is in the range of 22 - 28 MPa, and it can withstand large mechanical stresses. Especially in automotive safety glass, it can effectively improve the impact resistance and anti-fragmentation performance of the glass.

[0021] 3. The transparency and optical properties are optimized Different from the methods in the prior art to improve hydrolysis resistance by coating or adding additives, the modification process of the present invention does not affect the optical properties of the EMAA-Na + material. By reducing the Na +The MAA is reduced to MAA, and the modified material exhibits excellent optical effects in terms of light transmittance and haze, enabling high light transmittance and low haze. This makes the modified EMAA-Na + material particularly suitable for application scenarios with high transparency requirements, such as building curtain walls and automotive front windshield glass, etc.

[0022] Maintaining the high transparency of the material is crucial for laminated glass applications, especially in the automotive industry. The light transmittance of the front windshield not only affects the driver's vision but also directly relates to driving safety. Therefore, the modified material of the present invention can maintain high light transmittance while providing excellent hydrolysis resistance, and it is an innovative material with both safety and aesthetics.

[0023] 4. The preparation process is simple and suitable for large-scale industrial production The modified process flow of the present invention is relatively simple and does not introduce complex process steps, such as multi-layer coatings or expensive hydrolysis-resistant additives, etc., and has good potential for industrial production. Through steps such as liquid nitrogen pulverization, hydrochloric acid reduction, buffer solution regulation, and catalyst-assisted reaction, etc., the controllability of the process and the consistency of material properties are ensured. Especially the metal catalyst introduced during the reaction, zinc chloride can ionize into Zn 2+ and Cl -, wherein Zn 2+ acts as a Lewis acid and reacts with the carboxylate (COO - ) group to form a temporary complex, enhancing the nucleophilic effect of Cl - on the sodium group. This complex makes Na + more easily substituted by Cl - , promoting the reduction of Na + MAA to generate MAA and NaCl; monoclinic zirconia, as a carrier with a high specific surface area, can effectively disperse zinc chloride particles and prevent their agglomeration, thereby increasing the exposure of active sites. In addition, protonic acid sites are easily formed on the surface of monoclinic zirconia, which synergistically acts with Zn 2+ as a Lewis acid, enabling the reaction rate to be significantly increased, reducing the reaction time, decreasing the probability of side reactions, and at the same time ensuring the purity and quality of the final product.

[0024] The chemical reagents used in the present invention, such as hydrochloric acid, ZnCl 2 , sodium bicarbonate, etc., are all common industrial chemicals, which are easy to obtain and have low costs. By-products such as sodium chloride are non-toxic and harmless and are easy to handle. Therefore, the modified EMAA-Na + material can be mass-produced at a low cost and is suitable for popularization and application in the automotive and construction industries.

[0025] 5. Environmental friendliness The raw materials and processes used in the modification method of the present invention meet the environmental protection requirements. By-products generated during the reaction, such as sodium chloride and carbon dioxide, do not pollute the environment. At the same time, chemicals such as hydrochloric acid and sodium bicarbonate used can be harmlessly treated through simple neutralization reactions, showing good environmental protection characteristics. Compared with traditional coating methods and additive methods, the modification process of the present invention reduces the impact on the environment and lowers the risks during the use of materials. Detailed implementation manners

[0026] Unless otherwise specified, the raw materials and reagents used in the present invention are all commercially available products or can be prepared by known methods.

[0027] 1. Testing the contents of three groups One of the key objectives of the present invention is to adjust the ratios of three groups: vinyl, methacrylic acid (MAA), and sodium methacrylate (Na + MAA). To accurately determine the contents of these groups, the following testing methods are adopted: Nuclear magnetic resonance spectroscopy (NMR) analysis Sample dissolution: Dissolve the material sample in heavy water (D 2 O) or deuterochloroform (CDCl 3 ) to prepare a solution sample for NMR testing.

[0028] 1 1H-NMR and 13 13C-NMR testing: Use a 400 MHz nuclear magnetic resonance spectrometer to perform 1 1H-NMR and 13 13C-NMR analysis.

[0029] Analysis method: Vinyl (CH 2 =CH 2 ) : In the 1 1H-NMR spectrum, the chemical shift of vinyl protons is usually in the range of δ 4.5 - 5.5 ppm.

[0030] Methacrylic acid (CH 2 =C(CH 3 )COOH): The proton signal on the double bond appears in the range of δ 5.6 - 6.2 ppm.

[0031] Sodium methacrylate (CH 2 =C(CH 3 )COONa): The characteristic peak of sodium methacrylate can be found in the range of δ 1.9 - 2.1 ppm.

[0032] Result analysis: By integrating different chemical shift signals, the relative contents of vinyl, methacrylic acid, and sodium methacrylate are determined.

[0033] Infrared spectroscopy (FTIR) analysis Sample preparation: Mix the sample with KBr to prepare a transparent tablet for FTIR testing.

[0034] Test conditions: Use a Fourier transform infrared spectrometer (FTIR) for testing, with a scanning range of 4000 - 400 cm -1 . Analysis method: The characteristic absorption peak of vinyl usually appears at 950 - 1000 cm -1 (C-H bending vibration).

[0035] The characteristic peak of methacrylic acid is located at 1700 cm -1 (C=O stretching vibration).

[0036] Sodium methacrylate shows a symmetric stretching vibration peak of COO⁻ at 1550 cm -1 Result analysis: According to the intensity comparison of the absorption peaks, the relative contents of vinyl, methacrylic acid, and sodium methacrylate in the material are confirmed.

[0037] Result analysis: The relative contents of vinyl, methacrylic acid, and sodium methacrylate in the material are confirmed based on the intensity comparison of the absorption peaks.

[0038] 2. Adhesion test The adhesion test is used to determine the adhesion performance of the material to substrates such as glass and metal. This is very important for the modified EMAA-Na used in laminated glass or other adhesive materials. + Very important.

[0039] Adhesion test method: Test equipment: Use an electronic tensile testing machine to measure the adhesion.

[0040] Sample preparation: Uniformly coat the material sample on a glass substrate or a metal substrate, ensure a consistent coating thickness, and conduct the test after it is completely cured.

[0041] Test process: Clamp the substrate on the fixed device of the tensile testing machine, apply tensile force through the upper and lower fixtures until the sample peels off from the substrate, and record the maximum tensile force value during the peeling process.

[0042] Result analysis: The adhesion is expressed as the tensile force per unit area (N / cm²), and it should generally reach 30 - 45 N / cm², indicating good adhesion performance of the material..

[0043] 3. Transmittance and haze test Transmittance and haze are important indicators for evaluating the optical properties of materials, especially for materials used in laminated glass or transparent films.

[0044] Transmittance and haze test method: Testing equipment: Use a light transmittance / haze meter to test the light transmission performance of the material in the visible light band.

[0045] Sample preparation: Make the material into a thin sheet with a thickness of 1 - 3 mm, ensuring that the surface is flat and free of bubbles.

[0046] Testing process: Place the sample in the optical path of the meter, test the light transmittance, measure the intensity of the light after passing through the sample, calculate the transmittance. At the same time, the meter will measure the light scattering phenomenon to obtain the haze value.

[0047] Result analysis: Transmittance: The transmittance is required to be between 89 - 91%, ensuring that the material has good transparency. Haze: The haze should be less than 0.4%, ensuring that the material has a clear optical effect.

[0048] 4. Tensile strength test Tensile strength reflects the tensile resistance of the material when subjected to tensile force and is an important test item for the mechanical properties of the material.

[0049] Tensile strength test method: Testing equipment: Electronic universal tensile testing machine Sample preparation: Process the material into a standard dumbbell-shaped specimen with a length of 100 mm and a width of 10 mm.

[0050] Testing process: Fix the sample between the upper and lower fixtures of the tensile testing machine, apply tensile force evenly until the sample breaks. Record the maximum tensile force value and calculate the tensile strength through the formula. Calculation formula: σ = F / A Among them, σ is the tensile strength, F is the maximum tensile force, and A is the initial cross-sectional area of the sample.

[0051] Result analysis: The tensile strength of the material should be in the range of 22 - 28 MPa, indicating that it has sufficient mechanical strength.

[0052] 1.5 Shore hardness test Shore hardness is used to measure the surface hardness of materials and is an important indicator for evaluating the wear resistance and deformation resistance of materials.

[0053] Shore hardness test method: Testing equipment: Use a Shore hardness tester. Usually, Shore A or Shore D hardness testers are selected, specifically based on the material hardness range.

[0054] Sample preparation: Prepare the material into a flat plate with a standard thickness, ensuring that the surface is smooth.

[0055] Testing process: Press the probe of the hardness tester into the surface of the sample and maintain for a certain period of time. Record the hardness value corresponding to the depth of the probe penetration.

[0056] Result analysis: The Shore hardness value should generally be in the range of 60 - 80. A higher Shore hardness value indicates that the material has good wear resistance and compressive ability.

[0057] EMAA-Na + (Ethylene-methacrylic acid-sodium methacrylate copolymer) is prepared by the conventional free radical copolymerization of ethylene (Ethylene, E), methacrylic acid (Methacrylic acid, MAA) and sodium methacrylate (Sodium methacrylate, Na + MAA) or purchased directly from the market. Example 1

[0058] Material preparation: Take ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, freeze it to -196 °C with liquid nitrogen, maintain for 20 - 30 minutes, and crush it to a particle size of 30 microns; Reduction reaction: Add the crushed EMAA-Na + powder into 1.5 M hydrochloric acid solution, prepare the solution according to the ratio of 50 g EMAA-Na + : 200 mL 1.5 M hydrochloric acid, heat it to 100 °C under the condition of 300 rpm, boil and react for 2 hours. Add phosphate buffer solution during the reaction to control the pH value between 3.5 - 4.0, and add zinc chloride, with the dosage being 0.5% of the total mass of the reaction solution; Neutralization treatment: After the reaction is completed, use 0.5 M sodium bicarbonate solution to neutralize the residual hydrochloric acid, then wash it three times with deionized water to remove by-products such as sodium chloride, and perform vacuum freeze-drying treatment to obtain the modified hydrolysis-resistant EMAA-Na + copolymer.

[0059] Group content test: Vinyl content: 75.5%, methacrylic acid content: 18%, sodium methacrylate content: 6.5%. Other test results are: adhesive force is 38 N / cm², light transmittance is 90%, haze is 0.3%, tensile strength is 25 MPa, and Shore hardness is 70. Example 2

[0060] Material preparation: Take ethylene-methacrylic acid-sodium methacrylate (EMAA-Na +Copolymer, frozen to -196 °C using liquid nitrogen, maintained for 20 - 30 minutes, and crushed to a particle size of 30 microns; Reduction reaction: After crushing the EMAA-Na + powder was added to a 1.5 M hydrochloric acid solution, and the solution was prepared according to 40 g EMAA-Na + : 180 mL of 1.5 M hydrochloric acid. The reaction temperature was set at 95 °C, and the reaction was boiled for 3 hours. During the reaction, a phosphate buffer solution was added to adjust the pH value between 3.5 - 4.0, and zinc chloride was added, with a dosage of 1% of the total mass of the reaction solution; Neutralization treatment: After the reaction was completed, the residual hydrochloric acid was neutralized with 0.5 M sodium bicarbonate solution, and then washed four times with deionized water to remove by-products such as sodium chloride, and vacuum freeze-dried to obtain the modified hydrolysis-resistant EMAA-Na + copolymer.

[0061] Group content test: Vinyl content: 75.4%, Methacrylic acid content: 18.2%, Sodium methacrylate content: 6.4%, Other test results: Adhesion force is 36 N / cm², Light transmittance is 89%, Haze is 0.35%, Tensile strength is 24 MPa, Shore hardness is 68. Example 3

[0062] Material preparation: Take ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, frozen to -196 °C using liquid nitrogen, maintained for 20 - 30 minutes, and crushed to a particle size of 30 microns; Reduction reaction: After crushing the EMAA-Na + powder was added to a 1.5 M hydrochloric acid solution, and the solution was prepared according to the ratio of 50 g EMAA-Na + : 200 mL of 1.5 M hydrochloric acid. It was heated to 110 °C under the condition of 300 rpm, and the reaction was boiled for 1.5 hours. During the reaction, a phosphate buffer solution was added to adjust the pH value between 3.5 - 4.0, and zinc chloride was added, with a dosage of 0.7% of the total mass of the reaction solution; Neutralization treatment: After the reaction was completed, the residual hydrochloric acid was neutralized with 0.5 M sodium bicarbonate solution, and then washed four times with deionized water to remove by-products such as sodium chloride, and vacuum freeze-dried to obtain the modified hydrolysis-resistant EMAA-Na + copolymer.

[0063] Group content test: Vinyl content: 75.2%, Methacrylic acid content: 18.3%, Sodium methacrylate content: 6.5%, Other test results: Adhesion is 35 N / cm², Light transmittance is 89%, Haze is 0.4%, Tensile strength is 23 MPa, Shore hardness is 67. Example 4

[0064] Material preparation: Take ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, freeze it to -196 °C with liquid nitrogen, keep it for 20 - 30 minutes, and crush it to a particle size of 30 microns; Reduction reaction: Add the crushed EMAA-Na + powder to 1.5 M hydrochloric acid solution, prepare the solution according to the ratio of 50 g EMAA-Na + : 200 mL 1.5 M hydrochloric acid, heat it to 85 °C under the condition of 300 rpm, boil and react for 4 hours, add phosphate buffer solution during the reaction to control the pH value between 3.5 - 4.0, and add zinc chloride, with the dosage being 0.6% of the total mass of the reaction solution; Neutralization treatment: After the reaction is completed, neutralize the residual hydrochloric acid with 0.5 M sodium bicarbonate solution, then wash it four times with deionized water to remove by-products such as sodium chloride, and perform vacuum freeze-drying treatment to obtain the modified hydrolysis-resistant EMAA-Na + copolymer.

[0065] Group content test: Vinyl content: 75.4%, Methacrylic acid content: 18.3%, Sodium methacrylate content: 6.3%, Other test results: Adhesion is 37 N / cm², Light transmittance is 90%, Haze is 0.35%, Tensile strength is 25 MPa, Shore hardness is 69. Example 5

[0066] Material preparation: Take ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, freeze it to -196 °C with liquid nitrogen, keep it for 20 - 30 minutes, and crush it to a particle size of 30 microns; Reduction reaction: Add the crushed EMAA-Na + powder to 1.5 M hydrochloric acid solution, prepare the solution according to the ratio of 50 g EMAA-Na +Prepare a solution according to the ratio of 200 mL of 1.5 M hydrochloric acid, heat it to 100 °C under the condition of 300 rpm, boil and react for 2 hours. During the reaction, add phosphate buffer solution to adjust the pH value between 3.5 - 4.0, and add zinc chloride and monoclinic zirconia with a mass ratio of 1:2 and a dosage of 1% of the total mass of the reaction solution; Neutralization treatment: After the reaction is completed, use 0.5 M sodium bicarbonate solution to neutralize the residual hydrochloric acid, then wash it three times with deionized water to remove by-products such as sodium chloride, and perform vacuum freeze-drying treatment to obtain the modified hydrolysis-resistant EMAA-Na + copolymer.

[0067] Group content test: Vinyl content: 75.3%, methacrylic acid content: 20.4%, sodium methacrylate content: 4.3%. Other test results are: adhesion force is 41 N / cm², light transmittance is 93%, haze is 0.2%, tensile strength is 28 MPa, and Shore hardness is 73. Example 6

[0068] Material preparation: Take ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, freeze it to -196 °C with liquid nitrogen, keep it for 20 - 30 minutes, and crush it to a particle size of 30 microns; Reduction reaction: Add the crushed EMAA-Na + powder into 1.5 M hydrobromic acid solution, and prepare a solution according to the ratio of 50 g EMAA-Na + : 200 mL of 1.5 M hydrobromic acid, heat it to 100 °C under the condition of 300 rpm, boil and react for 2 hours. During the reaction, add phosphate buffer solution to adjust the pH value between 3.5 - 4.0, and add zinc chloride with a dosage of 0.5% of the total mass of the reaction solution; Neutralization treatment: After the reaction is completed, use 0.5 M sodium bicarbonate solution to neutralize the residual hydrobromic acid, then wash it three times with deionized water to remove by-products such as sodium bromide, and perform vacuum freeze-drying treatment to obtain the modified hydrolysis-resistant EMAA-Na + copolymer.

[0069] Group content test: Vinyl content: 75.7%, methacrylic acid content: 17.9%, sodium methacrylate content: 6.4%. Other test results are: adhesion force is 37 N / cm², light transmittance is 89%, haze is 0.35%, tensile strength is 26 MPa, and Shore hardness is 70.

[0070] Comparative Example 1 Material preparation: EMAA-Na copolymer prepared by conventional free radical copolymerization + copolymer

[0071] Group content test: Vinyl content: 76.5%, Methacrylic acid content: 14%, Sodium methacrylate content: 9.5%. Other performance tests: Adhesion force is 20 N / cm², Light transmittance is 85%, Haze is 0.8%, Tensile strength is 18 MPa, Shore hardness is 60

[0072] Comparative example 2 The difference between this comparative example and Example 1 is: Zinc chloride is not added, and the rest is exactly the same as Example 1

[0073] Group content test: Vinyl content: 75.8%, Methacrylic acid content: 15.8%, Sodium methacrylate content: 8.4%. Other performance tests: Adhesion force is 28 N / cm², Light transmittance is 87%, Haze is 0.5%, Tensile strength is 20 MPa, Shore hardness is 65

[0074] Comparative example 3 The difference between this comparative example and Example 1 is: Phosphate buffer solution is not added to adjust the pH value, and the rest is exactly the same as Example 1

[0075] Group content test: Vinyl content: 75.9%, Methacrylic acid content: 16%, Sodium methacrylate content: 8.1%. Other performance tests: Adhesion force is 30 N / cm², Light transmittance is 86%, Haze is 0.6%, Tensile strength is 21 MPa, Shore hardness is 62

[0076] From the performance test data of Examples 1-6 and Comparative examples 1-3 in the table, it can be seen that by modifying the ethylene-methacrylic acid-sodium methacrylate (EMAA-Na + ) copolymer, the key performance indicators such as the adhesion force, light transmittance, haze, tensile strength and Shore hardness of the material are significantly improved, especially in terms of hydrolysis stability and optical properties

[0077] 1. Analysis of vinyl, methacrylic acid and sodium methacrylate contents In Examples 1-6, the contents of vinyl, methacrylic acid, and sodium methacrylate were consistent with those of the genuine SGP material. In Comparative Example 1, the vinyl content was 76.5%, the methacrylic acid content decreased to 14%, and the sodium methacrylate content increased to 9.5%. This is because without modification, the proportion of sodium methacrylate in the material is relatively high, making it prone to hydrolysis, thus affecting the performance. In Comparative Examples 2 and 3, the vinyl and methacrylic acid contents were slightly improved, but due to the lack of a catalyst or pH regulation, the sodium methacrylate content was still too high, indicating that no effective reduction reaction occurred.

[0078] It can be seen that the catalyst and pH control during the modification process are crucial for adjusting the group content, which can significantly improve the efficiency of the reduction reaction, ensure the effective reduction of sodium methacrylate groups in the material to methacrylic acid, optimize the chemical composition of the material, and prevent hydrolysis.

[0079] 2. Adhesion analysis The adhesion in the modified Examples 1-6 was excellent, all between 35 N / cm² and 40 N / cm², with a maximum of 41 N / cm² (Example 5), far higher than that in the comparative examples (the lowest was only 20 N / cm²). In Comparative Example 1, due to the relatively large number of sodium methacrylate groups, it was prone to react with water, resulting in a sharp drop in adhesion. The adhesion of Comparative Examples 2 and 3 was also inferior to that of the examples because the catalyst and pH regulation were not used, the reaction was incomplete, and the chemical stability of the material was insufficient.

[0080] Therefore, the catalyst and appropriate pH value control in the examples significantly enhanced the adhesion of the EMAA-Na + material, indicating that the modified material can provide stronger adhesion in the application of laminated glass, especially in a humid environment.

[0081] 3. Transmittance and haze analysis Transmittance and haze are two important indicators for evaluating the optical properties of materials. The transmittance in Examples 1-6 was generally between 89% and 93%, while the haze was between 0.2% and 0.4%, far superior to that of the comparative examples (the lowest transmittance was 85% and the haze was as high as 0.8%). Especially in Example 5, the transmittance reached 93% and the haze was 0.2%, showing excellent transparency and low haze.

[0082] The transmittance of unmodified Comparative Example 1 was the lowest, which was related to its relatively high sodium methacrylate content, resulting in more light scattering inside the material and an increase in haze. The optical properties of Comparative Examples 2 and 3 were improved to some extent, but still lower than those of the examples, indicating that the regulation of the catalyst and buffer solution also played an important role in ensuring the optical properties of the material.

[0083] 4. Tensile Strength and Shore Hardness Analysis In terms of tensile strength, the materials of Examples 1 - 6 showed good tensile resistance, with values between 23 MPa and 28 MPa, which were better than that of Comparative Example 1 (only 18 MPa). In particular, the tensile strength of Example 5 reached 28 MPa, indicating that the material had good anti - deformation ability under mechanical stress. Although Comparative Examples 2 and 3 had some improvements, the lack of catalyst or pH regulation made the mechanical properties of the materials inferior to those of the examples. In terms of Shore hardness, the hardness range of the examples was from 67 to 73, showing excellent surface hardness and wear resistance. In particular, the Shore hardness of Example 5 reached 73, indicating that the material had good compressive properties and was suitable for use in laminated glass to provide long - term physical protection. The hardness of Comparative Example 1 was only 60, which was also due to the destruction of the internal structure of the material caused by hydrolysis.

[0084] It can be seen from the data analysis that the modified EMAA - Na + material showed obvious improvements in adhesion, optical properties and mechanical properties, especially in terms of hydrolysis stability, which was greatly improved. By adding a catalyst and controlling the pH value during the reaction process, the sodium methacrylate group was effectively restored, reducing the hydrolysis sensitivity and ensuring the long - term stability of the material in a high - humidity environment. The modified material had higher adhesion and transparency, and the tensile strength and Shore hardness were also significantly enhanced, making it very suitable for applications such as architectural and automotive laminated glass that require high transparency and strong mechanical properties.

[0085] The above - mentioned is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered within the protection scope of the present invention.

Claims

1. A hydrolysis-resistant EMAA-Na for laminated glass + A method for modifying a copolymer, characterized in that: In an acidic system, EMAA-Na + Sodium methacrylate (Na + MAA) is converted into methacrylic acid (MAA), and after post-treatment, the hydrolysis-resistant EMAA-Na for laminated glass is obtained. + Copolymer.

2. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 1 + A method for modifying a copolymer, characterized in that: The EMAA-Na + The copolymer also includes a pre-treatment step before the catalytic reaction, wherein the pre-treatment step is to freeze the copolymer with liquid nitrogen and then crush the copolymer to a particle size of 10-50 microns.

3. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 1 + A method for modifying a copolymer, characterized in that: The acidic system is prepared using any one or more of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, hydrobromic acid, and acetic acid.

4. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 1 + A method for modifying a copolymer, characterized in that: In an acidic system, the pH of the system is regulated to 3.5-4 by a buffer solution.

5. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 4 + A method for modifying a copolymer, characterized in that: The buffer solution is a phosphate buffer or a Tris buffer.

6. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 1 + A method for modifying a copolymer, characterized in that: The metal catalyst is selected from any one or more of zinc chloride, ferric chloride, cupric chloride, aluminum chloride, aluminum oxide, zirconium oxide, and titanium oxide.

7. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 1 + A method for modifying a copolymer, characterized in that: The post-treatment method is: after the reaction, the residual acid is neutralized with a sodium bicarbonate solution, the product is washed with deionized water, the by-products are removed, and vacuum freeze-dried to obtain EMAA-Na2O3 resistant to hydrolysis. + Material.

8. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 1 + A method for modifying a copolymer, characterized in that: The acidic system is prepared by 1.5 M hydrochloric acid solution, the pH of the system is regulated to 3.5-4 by phosphate buffer, and boiled at 80-120° C. for 1-5 hours.

9. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 8 + A method for modifying a copolymer, characterized in that: The EMAA-Na + The mass volume ratio of the copolymer and 1.5 M hydrochloric acid is 30-60 g: 150-250 ml.

10. The hydrolysis-resistant EMAA-Na for laminated glass according to claim 9 + A method for modifying a copolymer, characterized in that: The amount of the metal catalyst used is 0.5%-1% of the total mass of the solution.