Special adhesive for thermal insulation material and preparation method thereof

Abstract

This invention belongs to the field of water-based building adhesives and provides a special adhesive for thermal insulation materials and its preparation method. The invention utilizes a two-component system of adhesive A and adhesive B, a core phase of a polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, and a flame-retardant core-shell latex particle intermediate design with a phosphorus-boron flame-retardant component shell. Combined with the dispersion control of ammonium polyphosphate, sodium tetraborate decahydrate, sodium polyacrylate, and fillers, it achieves a coordinated improvement in bonding strength, flame retardancy, dispersion stability, and free water-soluble phosphorus-boron salt content. This solves the problem of balancing mechanical strength and flame retardancy, dispersion stability and the tendency of flame-retardant components in water-based adhesive systems, making it suitable for bonding thermal insulation materials to substrates.

Description

Technical Field

[0001] This invention relates to the field of water-based building adhesives, specifically to a special adhesive for thermal insulation materials and its preparation method. Background Technology

[0002] Building insulation systems are widely used in exterior walls, roofs, cold storage facilities, pipelines, and prefabricated building envelopes. Their adhesive layers not only serve to fix the insulation panels to the substrate but also directly affect construction efficiency, service durability, and fire safety. Water-based ethylene-vinyl acetate adhesives have a solid foundation in insulation material bonding due to their low odor during application, flexible film formation, and adaptability to various porous substrates. With increasing demands for energy-efficient buildings and flame-retardant safety, adhesives not only need to form continuous, uniform, and resilient adhesive layers but also need to maintain workable viscosity, coating continuity, storage redispersibility, and post-curing flame-retardant contribution even with inorganic fillers, flame-retardant components, and aqueous dispersions. Therefore, balancing bond strength, flame retardancy, dispersion stability, and low migration has become an important direction for the development of water-based adhesive systems specifically for insulation materials.

[0003] Existing technologies have proposed compounding polyvinyl acetate or ethylene-vinyl acetate film-forming systems with ammonium polyphosphate, borates, hydroxides, or other inorganic flame-retardant components to improve the flame retardancy of foam materials, wood, or insulation products. For example, Chinese patent CN105175990A discloses a flame-retardant coating adhesive for pre-foamed polystyrene beads, which constructs a flame-retardant coating layer through resin film-forming components and various flame retardants. However, its disclosure also reflects that there are still challenges in balancing storage and transportation friction, coating integrity, water resistance, and lightweight properties of the flame-retardant adhesive layer. Another Chinese patent CN103951870A involves flame-retardant EVA materials, indicating that combining the EVA system with phosphorus-based flame-retardant units is feasible. However, the molten material approach cannot directly solve the comprehensive problems of flame-retardant salt dispersion, low migration, and application window in water-based adhesives. Summary of the Invention

[0004] The purpose of this invention is to provide a special adhesive for thermal insulation materials and its preparation method, which solves the problem that it is difficult to simultaneously achieve both bonding strength and flame retardancy, dispersion stability and the tendency of flame retardant components to migrate in the current water-based ethylene-vinyl acetate adhesive system.

[0005] This invention utilizes a two-component combination of adhesive A and adhesive B, the construction of a flame-retardant core-shell latex particle intermediate, and a matched ratio of phosphorus-boron flame-retardant components. This allows the film-forming latex particles to maintain adhesive continuity. The phosphorus-boron components form a shell around the latex particles and reduce free migration. Sodium polyacrylate and a pre-dispersion process regulate the stability of the aqueous phase, thereby mitigating the side effects of reduced strength caused by flame-retardant filling and reduced flame-retardant contribution from organic film formation. In this invention, the phosphorus-boron shell can be an interfacial enrichment layer formed by ammonium polyphosphate and sodium tetraborate decahydrate around polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer latex particles. Its formation is related to hydrogen bonding, ion association, and interfacial adsorption between polyvinyl alcohol hydroxyl groups, phosphate groups, and borate groups on the latex particle surface. The phosphorus-boron shell is not limited to a covalently bonded layer.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A special adhesive for thermal insulation materials, the special adhesive for thermal insulation materials includes A glue and B glue, the mass ratio of A glue to B glue is 1:6 to 1:12; The mass percentage of component A in the A-grade adhesive formula, calculated based on the total mass of components used in the preparation of A-grade adhesive, includes: 100-260 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion; 15-80 parts of filler; 5-40 parts of phosphorus-boron flame retardant component; Furthermore, the A-type adhesive contains a flame-retardant core-shell latex particle intermediate, which is formed by latex particles in the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion as the core phase and the phosphorus-boron flame-retardant component as the shell component. B-type adhesive, by weight of input, includes: 5-50 parts of polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion; Ethylene-vinyl acetate copolymer can be redispersible latex powder in quantities of 0.4-6 parts; 1-15 parts of ammonium polyphosphate; Sodium tetraborate decahydrate 0.5-8 parts; Sodium polyacrylate 0.1-10 parts; And 150-500 portions of deionized water.

[0007] In this invention, the amounts of each component listed in Glue A are calculated based on the total mass of the ingredients added to the Glue A formulation throughout the entire preparation process. The core phase emulsion entering the flame-retardant core-shell latex particle intermediate, the ammonium polyphosphate and sodium tetraborate decahydrate from the shell layer, and similar emulsions added separately in the Glue A preparation steps are calculated by combining the actual amounts added. The 5-40 parts of the phosphorus-boron flame-retardant component refer to the total dry basis amount of ammonium polyphosphate and sodium tetraborate decahydrate used to form the shell layer of the flame-retardant core-shell latex particle intermediate in Glue A. Sodium polyacrylate, as a dispersion regulating component in the phosphorus-boron flame-retardant pre-dispersion, is calculated according to its respective pre-dispersion step and is not included in the mass of the phosphorus-boron flame-retardant component.

[0008] Furthermore, the filler is selected from one or more of calcium carbonate, talc, and quartz powder; the phosphorus-boron flame retardant component includes ammonium polyphosphate and sodium tetraborate decahydrate, and the mass ratio of ammonium polyphosphate to sodium tetraborate decahydrate is 100:5 to 100:45; the latex particle D50 of the flame retardant core-shell latex particle intermediate is 0.10-0.80 μm, the shell thickness is 5-60 nm, and the shell coverage is 70-98%.

[0009] Furthermore, the flame-retardant core-shell latex particle intermediate is prepared through the following steps: A1. Provide phosphorus-boron flame retardant predispersant solution; A2. A polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion is provided, wherein the mass ratio of ethylene-vinyl acetate copolymer dry basis to polyvinyl alcohol dry basis in the polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion is 100:1 to 100:8, the solid content is 45-65 wt%, and the pH value is 4.5-6.5; A3. Based on 100 parts by weight of ethylene-vinyl acetate copolymer dry basis, add 5-35 parts by weight of the dry basis component of the phosphorus-boron flame retardant pre-dispersion to the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion described in step A2, and adjust the pH value to 7.0-8.8. A4. Stir at 35-65℃ and normal air pressure for 1-4 hours to allow ammonium polyphosphate and sodium tetraborate decahydrate in the phosphorus-boron flame retardant predispersant to form a phosphorus-boron shell on the surface of the latex particles. A5. Aging at 30-55℃ for 0.5-2h, filtering and degassing to obtain the flame-retardant core-shell latex particle intermediate; The flame-retardant core-shell latex particle intermediate obtained after steps A4-A5 has a pH value of 7.0-8.8, a solid content of 35-60 wt%, a latex particle D50 of 0.10-0.80 μm, a shell thickness of 5-60 nm, a shell coverage of 70-98%, and a free water-soluble phosphorus-boron salt content of 0.5-20 wt%.

[0010] Furthermore, the phosphorus-boron flame retardant predispersant liquid in step A1 is prepared through the following steps: B1. Add 100 parts by weight of ammonium polyphosphate, 5-45 parts by weight of sodium tetraborate decahydrate, 0.5-6 parts by weight of sodium polyacrylate and 200-600 parts by weight of deionized water into a dispersion container; B2. Adjust the pH value to 7.5-9.0; B3. Stir at 20-45℃ and normal air pressure for 0.5-2 hours to obtain the phosphorus-boron flame retardant pre-dispersion; B4. The phosphorus-boron flame retardant predispersant has a solid content of 15-43 wt%, a viscosity of 10-800 mPa·s at 25°C, a D50 of 0.05-0.10 μm for the dispersed phase, and a pH of 7.5-9.0.

[0011] Furthermore, the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsions in adhesive A and adhesive B meet the following conditions: The dry basis content of ethylene-vinyl acetate copolymer is 45-65 wt%; The content of polyvinyl alcohol relative to the dry basis of ethylene-vinyl acetate copolymer is 1-8 wt%; The viscosity at 25℃ is 500-4500 mPa·s; pH value is 4.5-6.5; The D50 of latex particles is 0.08-0.60 μm.

[0012] Furthermore, the ethylene-vinyl acetate copolymer redispersible latex powder in the B-type adhesive contains ethylene-vinyl acetate copolymer and polyvinyl alcohol, wherein the mass ratio of ethylene-vinyl acetate copolymer to polyvinyl alcohol is 100:2 to 100:15.

[0013] Furthermore, the packing material has a D50 of 1-10 μm and a D90 of 3-25 μm.

[0014] Furthermore, in the flame-retardant core-shell latex particle intermediate, the mass ratio of ammonium polyphosphate to sodium tetraborate decahydrate is 100:5 to 100:45, and the content of the phosphorus-boron shell component in the flame-retardant core-shell latex particle intermediate relative to the dry basis of ethylene-vinyl acetate copolymer is 5-35 wt%.

[0015] Furthermore, the viscosity of the mixture of A and B at 25°C is 300-3500 mPa·s, and the pH value is 7.0-8.8.

[0016] Furthermore, the special adhesive for thermal insulation materials does not contain halogenated flame retardants, antimony-containing flame retardants, or fluoropolymers as flame retardant components, and the special adhesive for thermal insulation materials is a water-based adhesive.

[0017] This invention also discloses a method for preparing the above-mentioned special adhesive for thermal insulation materials, comprising the following steps: S1. Provides flame-retardant core-shell latex particle intermediates; S2. Preparation of A-adhesive: According to the feeding components and dosage of A-adhesive in the special adhesive for thermal insulation materials, the flame-retardant core-shell latex particle intermediate described in step S1 is mixed with the remaining feeding components of A-adhesive to obtain A-adhesive; S3. Preparation of B adhesive: According to the ingredients and dosage of B adhesive in the special adhesive for thermal insulation materials, mix the ingredients of B adhesive to obtain B adhesive; S4. Before use, mix the A glue and the B glue according to the mass ratio of A glue to B glue in the special adhesive for thermal insulation materials to obtain the special adhesive for thermal insulation materials.

[0018] Further, in step S2, the filler is first mixed with a portion of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, and then the flame-retardant core-shell latex particle intermediate described in step S1 is added to obtain adhesive A. In step S3, sodium polyacrylate is first dissolved in deionized water, and then polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, ethylene-vinyl acetate copolymer redispersible latex powder, ammonium polyphosphate and sodium tetraborate decahydrate are added in sequence to obtain glue B. In step S4, the construction time after mixing adhesive A and adhesive B is 0.5-8 hours.

[0019] As another aspect of this invention, the present invention employs a pre-preparation process involving flame-retardant core-shell latex particle intermediates, step-by-step preparation of Glue A and Glue B, and mixing before use. This process is primarily used to achieve, fix, or amplify the aforementioned synergistic effects. If the aqueous emulsion, filler, and phosphorus-boron flame-retardant salt are directly mixed in one step, the flame-retardant components are easily released in the aqueous phase, causing a local increase in salt concentration. While this may increase the flame-retardant contribution, it could disrupt the dispersion of latex particles, the application viscosity, and the continuity of the adhesive layer. Conversely, if the dispersion of the film-forming emulsion and filler is strengthened separately, the fixation degree of the phosphorus-boron components on the periphery of the latex particles may be reduced. This invention first forms a flame-retardant core-shell latex particle intermediate, then separately prepares Glue A containing the filler and the flame-retardant core-shell latex particle intermediate, and Glue B containing redispersible latex powder, ammonium polyphosphate, sodium tetraborate decahydrate, and sodium polyacrylate. These components are then mixed in proportion before use, ensuring that the shell state, dispersion state, and application window are maintained throughout the process sequence.

[0020] The method for using the above-mentioned special adhesive for thermal insulation materials includes the following steps: Mix the A and B components in the special adhesive for thermal insulation materials before use to obtain an application-ready adhesive solution. Within a construction time of 0.5-8 hours, the construction adhesive is applied to the surface of the insulation material and / or the surface of the substrate to be bonded by scraping, rolling, brushing, spraying or dot-and-frame application. The thermal insulation material is adhered to and compacted with the substrate to be bonded. After curing, it forms an adhesive layer with flame-retardant properties.

[0021] Furthermore, in the preparation of the flame-retardant core-shell latex particle intermediate, sodium hydroxide aqueous solution and acetic acid aqueous solution are used as pH adjusters. The concentrations of sodium hydroxide aqueous solution and acetic acid aqueous solution are both 0.1-1.0 mol / L. In step A3, the pH value of the system is adjusted to 7.0-8.8 by dropwise addition. The adjusted emulsion system then enters the shell formation process in step A4.

[0022] Furthermore, in step A4, the shell formation process uses latex particles in a polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion as the core phase, and ammonium polyphosphate and sodium tetraborate decahydrate in a phosphorus-boron flame-retardant pre-dispersion as the shell source. Under conditions of pH 7.0-8.8, temperature 35-65℃, absolute pressure 0.09-0.11 MPa, atmospheric pressure air atmosphere, and stirring time 1-4 h, a flame-retardant core-shell latex particle intermediate containing phosphorus (P) and boron (B) elements in its peripheral region is formed. The resulting flame-retardant core-shell latex particle intermediate then enters the A-resin preparation step. The atmospheric pressure air atmosphere in this invention indicates that the system does not require inert gas protection, and air does not participate in shell formation as a reactive oxidant.

[0023] Furthermore, in step A5, the filtration is carried out using an 80-150 mesh filtration method. The filtration target is the flame-retardant core-shell latex particle intermediate dispersion system aged for 0.5-2 hours. After filtration, the filtered dispersion system is allowed to stand for degassing for 30-60 minutes to obtain a uniform flame-retardant core-shell latex particle intermediate for the preparation of A glue.

[0024] Furthermore, in preparing the phosphorus-boron flame retardant predispersant solution, 100 parts by weight of ammonium polyphosphate, 5-45 parts by weight of sodium tetraborate decahydrate, 0.5-6 parts by weight of sodium polyacrylate, and 200-600 parts by weight of deionized water are added to a dispersion container. The pH value is then adjusted to 7.5-9.0 using sodium hydroxide aqueous solution and acetic acid aqueous solution, both with a concentration of 0.1-1.0 mol / L. Subsequently, the mixture is stirred for 0.5-2 hours at 20-45°C, an absolute pressure of 0.09-0.11 MPa, and a normal atmospheric pressure to obtain the phosphorus-boron flame retardant predispersant solution to proceed to step A3.

[0025] Furthermore, the particle size of the dispersed phase in the phosphorus-boron flame retardant pre-dispersion obtained in step B3 was determined by dynamic light scattering at 25°C. The test sample was taken from the dispersion after stirring in step B3, and the D50 and D90 of the dispersed phase were recorded. The D50 of the dispersed phase, which is 0.05-0.10 μm, was used as the quality control index for entering step A3. D50 and D90 were recorded according to the same dynamic light scattering intensity distribution.

[0026] Furthermore, the flame-retardant core-shell latex particle intermediate obtained in step A5 was characterized by transmission electron microscopy and cryosection. The test samples were taken from the flame-retardant core-shell latex particle intermediate after filtration and degassing. At least three fields of view with scales were recorded for each sample, and the shell thickness of at least 20 latex particles was counted. The obtained shell thickness data was used to characterize the shell thickness distribution of the flame-retardant core-shell latex particle intermediate.

[0027] Furthermore, TEM-EDS elemental surface scanning was performed on the flame-retardant core-shell latex particle intermediate obtained in step A5 to record the distribution images of P and B elements in the peripheral region of the latex particles. The shell coverage rate was calculated as the ratio of the projected area of ​​the latex particle's periphery corresponding to the continuous distribution area of ​​P and B elements to the total projected area of ​​the latex particle's periphery. The obtained shell coverage rate was used for structural quality control of the flame-retardant core-shell latex particle intermediate. The shell coverage rate of the same batch of samples was calculated using the same image analysis threshold and the same peripheral region delineation caliber.

[0028] Furthermore, the content of free water-soluble phosphorus-boron salts was determined based on the total mass of the flame-retardant core-shell latex particle intermediate obtained in step A5. The filtered and degassed flame-retardant core-shell latex particle intermediate was centrifuged to obtain an aqueous sample. The content of P and B elements in the aqueous sample was determined by inductively coupled plasma atomic emission spectrometry. The content of free water-soluble phosphorus-boron salts was obtained by calculating and adding the corresponding mass of water-soluble phosphorus and boron salts for P and B elements.

[0029] Furthermore, the viscosity at 25°C is expressed as the rotational viscosity reading of the aqueous dispersion system to be tested after being kept at 25°C. The aqueous dispersion system to be tested is selected from one of the following: phosphorus-boron flame retardant pre-dispersion, polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, and thermal insulation material adhesive after mixing A and B glues. Before testing, the aqueous dispersion system to be tested is stirred until it is uniform in appearance, and the obtained viscosity reading is used for the quality control of the corresponding system.

[0030] Further, in step S2, the filler and a portion of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion are premixed at 20-45°C for 10-40 min, and then the flame-retardant core-shell latex particle intermediate obtained in step S1 is added and mixed at 20-45°C for another 20-90 min to obtain Glue A containing the filler and the flame-retardant core-shell latex particle intermediate.

[0031] Further, in step S3, sodium polyacrylate is first dissolved in deionized water to form an aqueous phase of sodium polyacrylate. Then, polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, ethylene-vinyl acetate copolymer redispersible latex powder, ammonium polyphosphate and sodium tetraborate decahydrate are added sequentially at 15-40℃ and mixed for 20-120 min to obtain glue B.

[0032] Furthermore, the workable time after mixing adhesive A and adhesive B is taken as the starting point when adhesive A and adhesive B are mixed at a mass ratio of 1:6 to 1:12. The viscosity and coating state of the mixed thermal insulation material adhesive are recorded at 25°C. The workable time ends when the viscosity of the mixed thermal insulation material adhesive at 25°C exceeds 3500 mPa·s or cannot form a continuous and uniform coating layer.

[0033] Furthermore, A and B adhesives were stored in a sealed container at 5-35℃ for 7-60 days. After storage, the sedimentation state of A and B adhesives was observed, and the stored A and B adhesives were stirred until they were uniform in appearance. A and B adhesives that did not exhibit non-redispersible hard sedimentation and formed a uniform aqueous dispersion after stirring were then used in step S4 for mixing. The storage redispersibility rate was calculated as the ratio of the dry mass of non-redispersible sediment to the total dry solid mass of the sample. The calculation formula was: Storage redispersibility rate = (1 - dry mass of non-redispersible sediment / total dry solid mass of sample) × 100%; where non-redispersible sediment was defined as hard sediment that could not be redispersed after stirring the stored sample at 500 rpm for 10 min and was retained by an 80-mesh sieve. The mean and standard deviation of three parallel samples were recorded for each test group. The storage redispersibility rates in Table 1 were all calculated by combining the total dry solid mass of A and B adhesive samples after testing A and B adhesives separately at 35℃ for 60 days.

[0034] Furthermore, after mixing A and B adhesives at a mass ratio of 1:6 to 1:12, the mixture was kept at 25°C for 0.5-8 hours, and the resulting thermal insulation material adhesive was taken as a sample in use. The sample in use was subjected to particle size testing and peripheral distribution testing of P and B elements. The D50, shell thickness, and shell coverage of the latex particles were recorded. The recorded data were used to characterize the structural state of the flame-retardant core-shell latex particle intermediate after mixing A and B adhesives.

[0035] As another aspect of this invention, it employs a pre-mixing process followed by application, bonding, and compaction within the applicable construction time. This is primarily used to achieve, fix, or amplify the aforementioned synergistic effects. In the context of thermal insulation material bonding, if the viscosity of the workable adhesive increases too quickly or flame-retardant components migrate, it can easily lead to discontinuous coating layers, bonding interface defects, and uneven distribution of flame-retardant contributions. Excessive pursuit of fluidity may reduce the stability of the cured adhesive layer. This invention, by mixing adhesive A and adhesive B before use, limiting the applicable construction time, and employing methods such as scraping, rolling, brushing, spraying, or dot-and-frame application, allows the workable adhesive to form a relatively uniform aqueous dispersion layer on the surface of the thermal insulation material and the substrate to be bonded. After bonding, compaction, and curing, a flame-retardant adhesive layer is formed, thus continuing the aforementioned synergistic relationship during the construction process and the cured structure.

[0036] Beneficial technical effects 1. By using latex particles in a polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion as the core phase and phosphorus-boron flame retardant components to form the shell component, the film-forming units and flame-retardant units can be more closely connected in microscopic distribution, reducing the interference of free distribution of flame-retardant salts on the continuity of the adhesive layer, thus facilitating a balance between adhesive strength and flame retardant performance.

[0037] 2. By matching the ratio of ammonium polyphosphate to sodium tetraborate decahydrate, and combining it with sodium polyacrylate to regulate the dispersion of the phosphorus-boron flame retardant pre-dispersion, the risk of agglomeration and local enrichment of flame retardant components can be reduced, so that the water-based adhesive system can maintain a relatively stable dispersion state during storage, mixing and construction, thereby improving the balance between dispersion stability and control of free water-soluble phosphorus-boron salt content.

[0038] 3. By preparing A and B separately and mixing them by mass ratio before use, A, which contains filler and flame-retardant core-shell latex particle intermediates, can be stored separately from B, which contains redispersible latex powder and aqueous flame-retardant components. This reduces the risk of viscosity drift and sedimentation caused by premature interaction and helps maintain workability and coating continuity.

[0039] 4. By employing quality control methods such as filtration, static degassing, particle size control, shell thickness statistics, TEM-EDS elemental surface scanning, and determination of free water-soluble phosphorus-boron salt content, a traceable detection path can be provided for the structural state and free water-soluble phosphorus-boron salt content control of flame-retardant core-shell latex particle intermediates, thereby enhancing production scale-up and batch stability.

[0040] 5. By not adding halogenated flame retardants, antimony-containing flame retardants, or fluoropolymers as flame retardant components, and by using a water-based adhesive system, the dependence on high-halogen or antimony-containing flame retardant systems can be reduced in insulation material bonding scenarios, while meeting the multi-mode coating construction needs of insulation material surface and base layer surface. Attached Figure Description

[0041] Figure 1 The graph shows the effect of the mass ratio of adhesive A to adhesive B on bond strength and limiting oxygen index.

[0042] Figure 2 The graph shows the effect of the amount of phosphorus-boron flame retardant component in adhesive A on the bond strength and limiting oxygen index.

[0043] Figure 3 The graph shows the effect of the mass ratio of ammonium polyphosphate to sodium tetraborate decahydrate on shell coverage and the content of free water-soluble phosphorus-boron salts.

[0044] Figure 4 The graph shows the effect of pH value on shell coverage and bond strength in step A4.

[0045] Figure 5The image shows the DLS particle size difference distribution of Example 1 and related comparative samples.

[0046] Figure 6 This is a cumulative particle size distribution diagram of DLS in Example 1 and related comparative samples.

[0047] Figure 7 This is a differential distribution map of the shell thickness of TEM frozen sections of Example 1 and related comparative samples.

[0048] Figure 8 This is a cumulative distribution map of the shell thickness of TEM frozen sections of Example 1 and related comparative samples.

[0049] Figure 9 The image shows the scatter plot of TEM-EDS shell coverage and the standard deviation of the mean for Example 1 and related comparative samples.

[0050] Figure 10 This is a scatter plot of the ICP-OES free water-soluble phosphorus-boron salt content and its mean standard deviation for Example 1 and related comparative samples.

[0051] Figure 11 The graph shows the change in viscosity of the mixed adhesive over time for Example 1 and related comparative samples.

[0052] Figure 12 This is a scatter plot of the storage redispersion rate and the standard deviation of the mean for Example 1 and related comparative samples.

[0053] Figure 13 This is a scatter plot of the adhesive strength of Example 1 and related comparative samples, showing the mean and standard deviation.

[0054] Figure 14 This is a scatter plot of the limiting oxygen index and the standard deviation of the mean for Example 1 and related comparative samples.

[0055] Figure 15 The images show a comparison of macroscopic optical photographs of the final product of Example 1 and the final product of Comparative Example 9; where a is a macroscopic optical photograph of the final product of Example 1 and b is a macroscopic optical photograph of the final product of Comparative Example 9.

[0056] Figure 16 The images show a comparison of the SEM morphology of the final product of Example 1 and the final product of Comparative Example 9; where a is a low-magnification SEM image of the final product of Example 1, b is a low-magnification SEM image of the final product of Comparative Example 9, c is a medium-magnification SEM image of the final product of Example 1, d is a medium-magnification SEM image of the final product of Comparative Example 9, e is a high-magnification SEM image of the final product of Example 1, and f is a high-magnification SEM image of the final product of Comparative Example 9.

[0057] Figure 17The images show a comparison of the TEM structures of the final product of Example 1 and the final product of Comparative Example 9; where a is a bright-field TEM image of the final product of Example 1, b is a bright-field TEM image of the final product of Comparative Example 9, c is an HRTEM image of the final product of Example 1, d is an HRTEM image of the final product of Comparative Example 9, e is a TEM-EDS elemental distribution map of the final product of Example 1, and f is a TEM-EDS elemental distribution map of the final product of Comparative Example 9.

[0058] Figure 18 The images show the evolution of macroscopic optical photographs of the phosphorus-boron flame-retardant predispersant, flame-retardant core-shell latex particle intermediate, A-type glue, and A / B mixed glue in Example 1; where a is a macroscopic optical photograph of the phosphorus-boron flame-retardant predispersant, b is a macroscopic optical photograph of the flame-retardant core-shell latex particle intermediate, c is a macroscopic optical photograph of A-type glue, and d is a macroscopic optical photograph of the A / B mixed glue. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0060] Example 1 This embodiment prepares a special adhesive for low-ratio water-based thermal insulation materials. The preparation scale is based on 1000g of adhesive A. The product form is a water-based adhesive in which adhesives A and B are packaged separately and mixed before use. All raw materials are commercially available or commercially purchased general raw materials, without using specific brand and manufacturer names. The polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion has an ethylene-vinyl acetate copolymer dry basis content of 45wt%, a polyvinyl alcohol content relative to the ethylene-vinyl acetate copolymer dry basis of 1wt%, a viscosity of 500mPa·s at 25°C, a pH value of 4.5, and a latex particle D50 of 0.08μm. Calcium carbonate is used as the filler, with a D50 of 1μm and a D90 of 3μm. The mass ratio of ethylene-vinyl acetate copolymer to polyvinyl alcohol in the ethylene-vinyl acetate copolymer redispersible latex powder is 100:2.

[0061] Step B1: Add 100 parts by weight of ammonium polyphosphate, 5 parts by weight of sodium tetraborate decahydrate, 0.5 parts by weight of sodium polyacrylate, and 200 parts by weight of deionized water to a dispersion container. The ammonium polyphosphate is a commercially available industrial-grade powder, the sodium tetraborate decahydrate is a commercially available industrial-grade solid, the sodium polyacrylate is a commercially available water treatment-grade dispersing powder, and the deionized water has a conductivity ≤10 μS / cm.

[0062] Step B2: Adjust the pH value to 7.5 by adding 0.1 mol / L sodium hydroxide aqueous solution and 0.1 mol / L acetic acid aqueous solution dropwise at 25℃. During the dropwise addition, mechanically stir at 300 rpm to maintain the uniformity of the system. The pH value changes by no more than 0.05 for 5 consecutive minutes as the criterion for completion of adjustment.

[0063] Step B3: The phosphorus-boron flame retardant pre-dispersion was obtained by stirring at 500 rpm for 0.5 h at 20℃, absolute pressure 0.09 MPa, and atmospheric pressure air. After stirring, a sample was taken, and the dispersed phase D50 was 0.05 μm, D90 was 0.08 μm, solid content was 34.5 wt%, viscosity was 10 mPa·s, and pH was 7.5 at 25℃, measured by dynamic light scattering method.

[0064] Step A2: Provide a polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion. Take 50 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion as the core phase emulsion of this embodiment. The core phase emulsion of this embodiment has a mass ratio of ethylene-vinyl acetate copolymer dry basis to polyvinyl alcohol dry basis of 100:1, a solid content of 45wt%, and a pH value of 4.5.

[0065] Step A3: Based on 100 parts by weight of ethylene-vinyl acetate copolymer dry basis, add 22.3 parts by weight of the dry basis component of phosphorus-boron flame retardant pre-dispersion to the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion in step A2. The addition is completed dropwise over 20 minutes. The pH of the system is adjusted to 7.0 using 0.1 mol / L sodium hydroxide aqueous solution and 0.1 mol / L acetic acid aqueous solution.

[0066] Step A4: Stir at 600 rpm for 1 hour at 35℃, 0.09 MPa absolute pressure, and normal air atmosphere to allow ammonium polyphosphate and sodium tetraborate decahydrate in the phosphorus-boron flame retardant pre-dispersion to distribute on the surface of the latex particles and form a phosphorus-boron shell. The stirring endpoint was determined by the system having a uniform appearance, no visible coarse particles, and a stable pH value of 7.0 ± 0.1.

[0067] Step A5: Aging at 30℃ for 0.5h, filtering using an 80-mesh filtration method, and then allowing to stand for 30min to degas, yielding a flame-retardant core-shell latex particle intermediate. The intermediate has a pH of 7.0, a solid content of 35wt%, a latex particle D50 of 0.10μm, a shell thickness of 5nm, a shell coverage of 70%, and a free water-soluble phosphorus-boron salt content of 0.5wt%.

[0068] Step S2: Preparation of Glue A. Weigh out 100 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 15 parts of calcium carbonate filler, and 5 parts of phosphorus-boron flame retardant component according to the total mass proportions included in the Glue A formulation. Of these, 50 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion and 5 parts of the phosphorus-boron flame retardant component are used to prepare the flame-retardant core-shell latex particle intermediate obtained in Step A5, and the remaining 50 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion are used for premixing Glue A. First, premix the calcium carbonate filler with the 50 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion used for premixing Glue A at 20°C and 400 rpm for 10 min. Then, add the flame-retardant core-shell latex particle intermediate obtained in Step S1 and continue mixing at 20°C for 20 min to obtain Glue A.

[0069] Step S3: Preparation of Glue B. Weigh out 5 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 0.4 parts of ethylene-vinyl acetate copolymer redispersible latex powder, 1 part of ammonium polyphosphate, 0.5 parts of sodium tetraborate decahydrate, 0.1 parts of sodium polyacrylate, and 150 parts of deionized water according to the following mass ratios: First, dissolve sodium polyacrylate in deionized water to form an aqueous phase of sodium polyacrylate. Then, add the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, ethylene-vinyl acetate copolymer redispersible latex powder, ammonium polyphosphate, and sodium tetraborate decahydrate sequentially at 15°C. Mix at 400 rpm for 20 min to obtain glue B.

[0070] Step S4: Before use, mix adhesive A and adhesive B at a mass ratio of 1:6 and stir at 500 rpm for 5 minutes to obtain a special adhesive for thermal insulation materials. After mixing, the viscosity at 25℃ is 300 mPa·s, the pH value is 7.0, and the application time is 0.5 hours. Apply the workable adhesive to the surface of the molded polystyrene board and the cement mortar base surface by scraping, with a coating amount of 1.2 kg / m². After bonding, compact with a pressure of 0.02 MPa for 2 minutes, and cure for 7 days at 23℃ and 50% relative humidity to form an adhesive layer.

[0071] Quality testing methods and results: The viscosity of the mixed adhesive was measured to be 300 mPa·s at 25℃ using rotational viscosity reading; the pH value was measured to be 7.0 using a glass electrode pH meter; a frozen section of the flame-retardant core-shell latex particle intermediate was observed using transmission electron microscopy, and the average shell thickness of 20 latex particles was 5 nm; the shell coverage was calculated to be 70% using TEM-EDS elemental surface scanning; the free water-soluble phosphorus-boron salt content in the centrifuged aqueous phase was calculated to be 0.5 wt% using inductively coupled plasma atomic emission spectrometry. The adhesive in this embodiment has a uniform appearance with no visible coarse particles, making it suitable for bonding substrates with short application windows and low viscosity.

[0072] Features and application scenarios of this embodiment: This embodiment adopts a relatively conservative low-ratio scheme. The amount of each core material in glue A and glue B is in a low range. The shell thickness and shell coverage are low. The viscosity of the glue is low and the coating resistance is small. It is suitable for bonding small-area thermal insulation materials, thin-coat construction and on-site operations with high requirements for initial fluidity.

[0073] Example 2 Raw materials and proportions: This embodiment prepares a special adhesive for high-load water-based thermal insulation materials, with a preparation scale based on 1000g of adhesive A. The polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion has an ethylene-vinyl acetate copolymer dry basis content of 65wt%, a polyvinyl alcohol content relative to the ethylene-vinyl acetate copolymer dry basis of 8wt%, a viscosity of 4500mPa·s at 25℃, a pH value of 6.5, and a latex particle D50 of 0.60μm. Talc powder is used as the filler, with a D50 of 10μm and a D90 of 25μm. The mass ratio of ethylene-vinyl acetate copolymer to polyvinyl alcohol in the ethylene-vinyl acetate copolymer redispersible latex powder is 100:15.

[0074] Preparation of the pre-dispersion: 100 parts by weight of ammonium polyphosphate, 45 parts by weight of sodium tetraborate decahydrate, 6 parts by weight of sodium polyacrylate, and 600 parts by weight of deionized water were added to a dispersion container. The pH was adjusted to 9.0 at 25°C using a 1.0 mol / L sodium hydroxide aqueous solution and a 1.0 mol / L acetic acid aqueous solution, and the mixture was mechanically stirred at 900 rpm. Stirring was continued for 2 hours at 45°C, an absolute pressure of 0.11 MPa, and atmospheric pressure to obtain the phosphorus-boron flame retardant pre-dispersion. The obtained phosphorus-boron flame retardant pre-dispersion had a solid content of 20.1 wt%, a viscosity of 800 mPa·s at 25°C, a dispersed phase D50 of 0.10 μm, a D90 of 0.16 μm, and a pH of 9.0.

[0075] Preparation process of flame-retardant core-shell latex particle intermediate: A polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion with a dry basis ratio of ethylene-vinyl acetate copolymer to polyvinyl alcohol (PVA) of 100:8, a solid content of 65 wt%, and a pH of 6.5 was provided. 200 parts of this emulsion were used as the core phase emulsion. Based on 100 parts by weight of the ethylene-vinyl acetate copolymer dry basis, 34.6 parts by weight of the dry basis component of a phosphorus-boron flame-retardant pre-dispersion was added to the emulsion within 40 min. The pH of the system was adjusted to 8.8 using a 1.0 mol / L sodium hydroxide aqueous solution and a 1.0 mol / L acetic acid aqueous solution. Subsequently, the mixture was stirred at 900 rpm for 4 h at 65 °C, an absolute pressure of 0.11 MPa, and an atmospheric pressure air atmosphere. It was then aged at 55 °C for 2 h, filtered through a 150-mesh filtration system, and allowed to stand for 60 min to remove bubbles, yielding the flame-retardant core-shell latex particle intermediate. The resulting intermediate had a pH of 8.8, a solid content of 60 wt%, a latex particle D50 of 0.80 μm, a shell thickness of 60 nm, a shell coverage of 98%, and a free water-soluble phosphorus-boron salt content of 20 wt%.

[0076] Preparation process of Glue A: Weigh out 260 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 80 parts of talc filler, and 40 parts of phosphorus-boron flame retardant component according to the total mass proportions of ingredients included in the Glue A formulation. Of these, 200 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion and 40 parts of the phosphorus-boron flame retardant component are used to prepare the flame-retardant core-shell latex particle intermediate, and the remaining 60 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion are used for premixing Glue A. First, premix the talc filler with the 60 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion used for premixing Glue A at 45℃ and 700 rpm for 40 min. Then, add the flame-retardant core-shell latex particle intermediate and continue mixing at 45℃ for 90 min to obtain Glue A.

[0077] Preparation process of Glue B: Weigh out 50 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 6 parts of ethylene-vinyl acetate copolymer redispersible latex powder, 15 parts of ammonium polyphosphate, 8 parts of sodium tetraborate decahydrate, 10 parts of sodium polyacrylate, and 500 parts of deionized water according to the following mass ratios: First, dissolve sodium polyacrylate in deionized water to form an aqueous phase of sodium polyacrylate. Then, add the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, ethylene-vinyl acetate copolymer redispersible latex powder, ammonium polyphosphate, and sodium tetraborate decahydrate sequentially at 40°C. Mix at 800 rpm for 120 min to obtain Glue B.

[0078] Application and Curing Process: Before use, mix Glue A and Glue B at a mass ratio of 1:12 and stir at 800 rpm for 8 minutes to obtain a special adhesive for thermal insulation materials. After mixing, the viscosity at 25℃ is 3500 mPa·s, the pH value is 8.8, and the application time is 8 hours. Apply the workable adhesive to the surface of the rock wool board and the concrete substrate by roller coating at a rate of 2.0 kg / m². After bonding, compact with a pressure of 0.05 MPa for 5 minutes and cure for 7 days at 23℃ and 50% relative humidity to form an adhesive layer.

[0079] Quality testing methods and results: The rotational viscosity at 25℃ was 3500 mPa·s; the pH value measured by the glass electrode pH meter was 8.8; the average shell thickness of 20 latex particles obtained by transmission electron microscopy (TEM) frozen sections was 60 nm; the shell coverage was calculated to be 98% by TEM-EDS elemental surface scanning; and the free water-soluble phosphorus-boron salt content calculated by inductively coupled plasma atomic emission spectrometry (ICP-AES) was 20 wt%. The adhesive solution in this embodiment exhibited a uniform, viscous, aqueous dispersion, and showed no non-redispersible hard sedimentation after stirring.

[0080] The features of this embodiment are as follows: This embodiment adopts an optimized scheme with a relatively high load. The ratio of A glue to B glue, the solid content of the emulsion, the amount of filler, the amount of phosphorus-boron flame retardant component, and the amount of each water-based component in B glue are all in a high range. It is suitable for bonding thermal insulation materials with high requirements for flame retardant contribution, thick coating adaptability, and long construction time.

[0081] Example 3 In this embodiment, the prepared material is a water-based thermal insulation material adhesive with a medium proportion and process conditions favoring mild conditions. The preparation scale is based on 1000g of adhesive A, with adhesive A and adhesive B mixed at a mass ratio of 1:8 before use. The filler is a combination of calcium carbonate and quartz powder, with calcium carbonate accounting for 60% of the total filler mass and quartz powder accounting for 40%. The filler D50 is 5μm and D90 is 12μm. The polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion has an ethylene-vinyl acetate copolymer dry basis content of 50wt%, a polyvinyl alcohol content relative to the ethylene-vinyl acetate copolymer dry basis of 3wt%, a viscosity of 1200mPa·s at 25°C, a pH value of 5.0, and a latex particle D50 of 0.20μm. The ethylene-vinyl acetate copolymer redispersible latex powder has an ethylene-vinyl acetate copolymer to polyvinyl alcohol mass ratio of 100:6.

[0082] The phosphorus-boron flame retardant predispersant solution of this embodiment was prepared as follows: 100 parts by weight of ammonium polyphosphate, 20 parts by weight of sodium tetraborate decahydrate, 2 parts by weight of sodium polyacrylate, and 300 parts by weight of deionized water were added to a dispersion container. The pH value was adjusted to 7.5 at 25°C using 0.3 mol / L sodium hydroxide aqueous solution and 0.3 mol / L acetic acid aqueous solution. The mixture was stirred at 600 rpm for 0.5 h at 20°C, absolute pressure of 0.09 MPa, and atmospheric pressure. The resulting phosphorus-boron flame retardant predispersant solution had a solid content of 28.9 wt%, a viscosity of 80 mPa·s at 25°C, a dispersed phase D50 of 0.06 μm, a D90 of 0.10 μm, and a pH value of 7.5.

[0083] The flame-retardant core-shell latex particle intermediate of this embodiment was prepared as follows: 90 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion were taken as the core phase emulsion. Based on 100 parts by weight of the dry basis of the ethylene-vinyl acetate copolymer, 34.9 parts by weight of the dry basis component of the phosphorus-boron flame-retardant pre-dispersion was added to the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion within 25 min. The pH value was adjusted to 7.0 by dropwise addition of 0.3 mol / L sodium hydroxide aqueous solution and 0.3 mol / L acetic acid aqueous solution. The system was stirred at 600 rpm for 1 h at 35 °C, absolute pressure 0.09 MPa, and atmospheric pressure air atmosphere, and then aged at 30 °C for 0.5 h. After filtration through an 80 mesh and standing for degassing for 30 min, the flame-retardant core-shell latex particle intermediate was obtained. The intermediate has a pH of 7.0, a solid content of 40 wt%, a latex particle D50 of 0.30 μm, a shell thickness of 12 nm, a shell coverage of 75%, and a free water-soluble phosphorus-boron salt content of 3 wt%.

[0084] In preparing Glue A, 150 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 35 parts of filler, and 15 parts of phosphorus-boron flame retardant component were weighed according to the total mass proportions of the ingredients included in the Glue A formulation. Of these, 90 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion and 15 parts of the phosphorus-boron flame retardant component were used to prepare the flame-retardant core-shell latex particle intermediate, and the remaining 60 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion were used for premixing Glue A. First, the filler and the 60 parts of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion used for premixing Glue A were premixed at 20°C and 500 rpm for 10 min. Then, the flame-retardant core-shell latex particle intermediate was added, and mixing continued at 20°C and 500 rpm for 20 min to obtain Glue A.

[0085] To prepare Glue B, weigh out 20 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 2 parts of ethylene-vinyl acetate copolymer redispersible latex powder, 5 parts of ammonium polyphosphate, 2 parts of sodium tetraborate decahydrate, 2 parts of sodium polyacrylate, and 250 parts of deionized water. First, add sodium polyacrylate to deionized water and stir at 500 rpm for 15 minutes at 15°C to form a homogeneous aqueous phase. Then, sequentially add the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, the ethylene-vinyl acetate copolymer redispersible latex powder, the ammonium polyphosphate, and the sodium tetraborate decahydrate, and mix at 15°C for 20 minutes to obtain Glue B.

[0086] Before use, mix adhesive A and adhesive B at a mass ratio of 1:8 and stir at 600 rpm for 6 minutes to obtain a special adhesive for thermal insulation materials. After mixing, the viscosity at 25℃ is 1200 mPa·s, the pH value is 7.2, and the application time is 2 hours. Apply the workable adhesive to the surface of extruded polystyrene board and cement mortar base surface by brushing, with a coating amount of 1.5 kg / m². After bonding, compact with a pressure of 0.03 MPa for 3 minutes, and cure for 7 days at 23℃ and 50% relative humidity to form an adhesive layer.

[0087] Quality testing methods and results: The rotational viscosity at 25℃ was 1200 mPa·s, and the pH value measured by the glass electrode pH meter was 7.2. After the sample was kept at 25℃ for 2 hours, the latex particle D50 was measured to be 0.32 μm by dynamic light scattering, the average shell thickness of the frozen section was 12 nm, and the shell coverage was calculated to be 74% by TEM-EDS elemental surface scanning. The applyable adhesive of this embodiment forms a continuous and uniform brush coating, and the adhesive layer has a continuous appearance after curing.

[0088] The applicable scenarios for this embodiment are as follows: This embodiment selects process conditions that are biased towards the low-value area and uses a combination of calcium carbonate and quartz powder fillers, which takes into account mild dispersion, brush application and medium viscosity. It is suitable for insulation board bonding operations with normal temperature construction, medium water absorption of the substrate and good coating spreadability.

[0089] Example 4 I. Preparation Object and Product Form: A water-based thermal insulation material adhesive was prepared using 1000g of adhesive A as a baseline. Adhesive A and adhesive B were stored separately and mixed at a mass ratio of 1:10 before use. The polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion had an ethylene-vinyl acetate copolymer dry basis content of 60wt%, a polyvinyl alcohol content relative to the ethylene-vinyl acetate copolymer dry basis of 6wt%, a viscosity of 3000 mPa·s at 25℃, a pH value of 6.0, and a latex particle D50 of 0.45μm. The filler consisted of a combination of calcium carbonate, talc, and quartz powder in a mass ratio of 40:30:30, with a filler D50 of 8μm and a D90 of 20μm. The redispersible latex powder of ethylene-vinyl acetate copolymer had an ethylene-vinyl acetate copolymer to polyvinyl alcohol mass ratio of 100:10.

[0090] II. Preparation of Phosphorus-Boron Flame Retardant Predispersant: 100 parts by weight of ammonium polyphosphate, 45 parts by weight of sodium tetraborate decahydrate, 6 parts by weight of sodium polyacrylate, and 600 parts by weight of deionized water were added to a dispersion container. The pH was adjusted to 9.0 at 25°C using 1.0 mol / L sodium hydroxide aqueous solution and 1.0 mol / L acetic acid aqueous solution. The mixture was then stirred at 850 rpm for 2 hours at 45°C, an absolute pressure of 0.11 MPa, and atmospheric pressure to obtain the phosphorus-boron flame retardant predispersant. The obtained predispersant had a solid content of 20.1 wt%, a viscosity of 800 mPa·s at 25°C, a dispersed phase D50 of 0.10 μm, a D90 of 0.18 μm, and a pH of 9.0.

[0091] III. Preparation of Flame-Retardant Core-Shell Latex Granule Intermediate: 185 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion were used as the core phase emulsion. Based on 100 parts by weight of the ethylene-vinyl acetate copolymer (dry basis), 34.8 parts by weight of the phosphorus-boron flame-retardant pre-dispersion (dry basis) were added to the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion over 45 min. The pH of the system was adjusted to 8.8 using 1.0 mol / L sodium hydroxide aqueous solution and 1.0 mol / L acetic acid aqueous solution. The system was stirred at 850 rpm for 4 h at 65℃, 0.11 MPa absolute pressure, and atmospheric pressure to allow ammonium polyphosphate and sodium tetraborate decahydrate in the phosphorus-boron flame-retardant pre-dispersion to form a phosphorus-boron shell layer on the surface of the latex granules. Subsequently, the mixture was aged at 55℃ for 2 h, filtered through a 150-mesh sieve, and allowed to stand for 60 min to remove bubbles, yielding the flame-retardant core-shell latex granule intermediate. The resulting intermediate had a pH of 8.8, a solid content of 60 wt%, a latex particle D50 of 0.80 μm, a shell thickness of 60 nm, a shell coverage of 98%, and a free water-soluble phosphorus-boron salt content of 12 wt%.

[0092] IV. Preparation of Glue A and Glue B: Glue A, calculated by weight in the entire Glue A formulation, includes 220 parts of polyvinyl alcohol (PVA) protective colloidal ethylene-vinyl acetate copolymer emulsion, 65 parts of filler, and 35 parts of phosphorus-boron flame retardant component. Of these, 185 parts of the PVA protective colloidal ethylene-vinyl acetate copolymer emulsion and 35 parts of the phosphorus-boron flame retardant component are used to prepare the flame-retardant core-shell latex particle intermediate, while the remaining 35 parts of the PVA protective colloidal ethylene-vinyl acetate copolymer emulsion are used for premixing Glue A. First, the filler and the 35 parts of the PVA protective colloidal ethylene-vinyl acetate copolymer emulsion used for premixing Glue A are premixed at 45°C for 40 minutes. Then, the flame-retardant core-shell latex particle intermediate is added, and mixing continues at 45°C for 90 minutes to obtain Glue A. Glue B, by weight, comprises 40 parts of polyvinyl alcohol protective colloid-type ethylene-vinyl acetate copolymer emulsion, 5 parts of ethylene-vinyl acetate copolymer redispersible latex powder, 12 parts of ammonium polyphosphate, 6 parts of sodium tetraborate decahydrate, 8 parts of sodium polyacrylate, and 420 parts of deionized water. First, the sodium polyacrylate is dissolved in deionized water to form an aqueous phase of sodium polyacrylate. Then, the remaining components of Glue B are added sequentially at 40°C and mixed for 120 minutes to obtain Glue B.

[0093] V. Evaluation of Use and Storage: Glue A and Glue B were stored separately at 35℃ in a sealed container for 60 days. After storage, the bottom settling status was observed, and Glue A and Glue B were stirred separately until uniform in appearance. No non-dispersible hard settling was observed after stirring. Before use, Glue A and Glue B were mixed at a mass ratio of 1:10 and kept at 25℃ for 8 hours. A sample of the mixed thermal insulation material adhesive was taken as a workable sample. After mixing, the viscosity at 25℃ was 3200 mPa·s, the pH value was 8.6, and the workable time was 8 hours. The workable adhesive was applied to the rock wool composite insulation board and the concrete substrate surface using a dot-and-frame application method. After bonding, it was compacted at a pressure of 0.04 MPa for 4 minutes and cured for 7 days at 23℃ and 50% relative humidity to form an adhesive layer.

[0094] Quality testing methods and results: The rotational viscosity of the mixed sample at 25℃ was 3200 mPa·s, and the pH value measured by a glass electrode pH meter was 8.6. After being kept at 25℃ for 8 hours in the usable state, the latex particle D50 was measured to be 0.78 μm by dynamic light scattering method, the average shell thickness of frozen sections was 58 nm, and the shell coverage was calculated to be 96% by TEM-EDS elemental surface scanning. After 60 days of storage, the A and B glues formed a uniform aqueous dispersion after stirring, with no non-redispersible hard sedimentation.

[0095] The process features and application directions of this embodiment: This embodiment adopts process conditions close to the high value region and high shell construction strength, taking into account high viscosity, long workability and storage redispersibility, and is suitable for large-area thermal insulation material laying, spot and frame coating and engineering construction with high requirements for storage period.

[0096] Comparative Example 1: Basically the same as Example 1, except that the total amount of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion included in the formulation of Glue A is 80 parts, of which 50 parts are used to prepare flame-retardant core-shell latex particle intermediates and 30 parts are used to prepare premixed Glue A. In step S2, the amount of calcium carbonate filler is 15 parts and the amount of phosphorus-boron flame retardant component is 5 parts. In Glue B, the amount of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion is 5 parts, the amount of ethylene-vinyl acetate copolymer redispersible latex powder is 0.4 parts, the amount of ammonium polyphosphate is 1 part, the amount of sodium tetraborate decahydrate is 0.5 parts, the amount of sodium polyacrylate is 0.1 parts, and the amount of deionized water is 150 parts. The mass ratio of Glue A to Glue B is 1:6. The temperature, time, pressure, pH value, stirring and filtration degassing conditions in steps B1 to B3, steps A2 to A5, steps S3 and S4 are kept as the key conditions fully listed in Example 1.

[0097] Comparative Example 2: Basically the same as Example 1, except that the amount of calcium carbonate filler in Glue A is 100 parts, the amount of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion in step S2 is 100 parts, and the amount of phosphorus-boron flame retardant component is 5 parts; the amount of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion in Glue B is 5 parts, the amount of ethylene-vinyl acetate copolymer redispersible latex powder is 0.4 parts, the amount of ammonium polyphosphate is 1 part, the amount of sodium tetraborate decahydrate is 0.5 parts, and the amount of polyacrylic acid is... Sodium was 0.1 parts, deionized water was 150 parts, and the mass ratio of A glue to B glue was 1:6. The temperature, time, pressure, pH value, stirring and filtration degassing conditions in steps B1 to B3, A2 to A5, S3 and S4 were kept to the key conditions fully listed in Example 1. The distribution diameter of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion in A glue for the preparation of flame retardant core-shell latex particle intermediates and the premixing of A glue was kept to the distribution diameter of Example 1.

[0098] Comparative Example 3: Essentially the same as Example 1, except that the amount of phosphorus-boron flame retardant component in Glue A is 2 parts, the amount of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion in step S2 is 100 parts, and the amount of calcium carbonate filler is 15 parts; in Glue B, the amount of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion is 5 parts, the amount of ethylene-vinyl acetate copolymer redispersible latex powder is 0.4 parts, the amount of ammonium polyphosphate is 1 part, the amount of sodium tetraborate decahydrate is 0.5 parts, and the amount of polyacrylic acid is... Sodium was 0.1 parts, deionized water was 150 parts, and the mass ratio of A glue to B glue was 1:6. The temperature, time, pressure, pH value, stirring and filtration degassing conditions in steps B1 to B3, A2 to A5, S3 and S4 were kept to the key conditions fully listed in Example 1. The distribution diameter of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion in A glue for the preparation of flame retardant core-shell latex particle intermediates and the premixing of A glue was kept to the distribution diameter of Example 1.

[0099] Comparative Example 4: Basically the same as Example 1, except that the shell formation temperature in step A4 is 25°C, the pH value in step A4 is 7.0, the absolute pressure is 0.09MPa, the atmospheric pressure air atmosphere is normal, the stirring time is 1h, the stirring speed is 600rpm, and step A5 is aging at 30°C for 0.5h, filtration at 80 mesh and standing for degassing for 30min, the mass ratio of A glue to B glue is 1:6, and the components and amounts of A glue and B glue are kept in accordance with the key conditions listed in Example 1.

[0100] Comparative Example 5: Basically the same as Example 1, except that the stirring time in step A4 is 0.3h, the temperature in step A4 is 35℃, the pH value is 7.0, the absolute pressure is 0.09MPa, the atmospheric pressure air atmosphere is normal, the stirring speed is 600rpm, and step A5 is aging at 30℃ for 0.5h, filtration at 80 mesh and standing for degassing for 30min. The mass ratio of A glue to B glue is 1:6, and the components and amounts of A glue and B glue are kept in accordance with the key conditions listed in Example 1.

[0101] Comparative Example 6: Basically the same as Example 1, except that the amount of sodium polyacrylate added in step B1 is 0.05 parts by mass, the amount of ammonium polyphosphate in step B1 is 100 parts by mass, the amount of sodium tetraborate decahydrate is 5 parts by mass, the amount of deionized water is 200 parts by mass, the pH value in step B2 is 7.5, and the stirring in step B3 is carried out at 20°C, absolute pressure of 0.09 MPa, and atmospheric pressure air atmosphere for 0.5 h. The components and amounts of A glue and B glue, the mass ratio of A glue to B glue, and the key conditions of steps A2 to A5 and steps S2 to S4 are kept as the key conditions listed in Example 1.

[0102] Comparative Example 7: Basically the same as Example 1, except that in step S4 the mass ratio of A glue to B glue is 1:4. In A glue, there are 100 parts of polyvinyl alcohol protective colloid type ethylene-vinyl acetate copolymer emulsion, 15 parts of calcium carbonate filler, and 5 parts of phosphorus-boron flame retardant component. In B glue, there are 5 parts of polyvinyl alcohol protective colloid type ethylene-vinyl acetate copolymer emulsion, 0.4 parts of ethylene-vinyl acetate copolymer redispersible latex powder, 1 part of ammonium polyphosphate, 0.5 parts of sodium tetraborate decahydrate, 0.1 parts of sodium polyacrylate, and 150 parts of deionized water. Steps B1 to B3, steps A2 to A5, steps S2 and S3 are kept in accordance with the key conditions fully listed in Example 1.

[0103] Comparative Example 8: It is basically the same as Example 1, except that in step A5, the filtration is carried out by 40-mesh filtration and the mixture is allowed to stand for 10 minutes to degas. In step A5, the aging temperature is 30°C and the aging time is 0.5 hours. The mass ratio of A glue to B glue is 1:6. The ingredients and amounts of A glue and B glue, and the key conditions of steps B1 to B3, A2 to A4, and S2 to S4 are kept as the key conditions listed in Example 1.

[0104] Comparative Example 9: Essentially the same as Example 1, except that the shell formation treatment of the flame-retardant core-shell latex particle intermediate is omitted in steps A3 to A5. In Glue A, 100 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 15 parts of calcium carbonate filler, and 5 parts of phosphorus-boron flame-retardant component are directly added. In Glue B, 5 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, 0.4 parts of ethylene-vinyl acetate copolymer redispersible latex powder, 1 part of ammonium polyphosphate, 0.5 parts of sodium tetraborate decahydrate, 0.1 parts of sodium polyacrylate, and 150 parts of deionized water are added. The mass ratio of Glue A to Glue B is 1:6. The temperature, time, stirring, and coating conditions in steps S2 to S4 are maintained as the key conditions fully specified in Example 1. This comparative example is used to investigate the synergistic relationship between the latex particle core phase and the phosphorus-boron shell.

[0105] Comparative Example 10: Essentially the same as Example 1, except that in step B1 only 100 parts by weight of ammonium polyphosphate, 0.5 parts by weight of sodium polyacrylate, and 200 parts by weight of deionized water were added; sodium tetraborate decahydrate was not added. In step B2, the pH was 7.5. In step B3, stirring was carried out at 20°C, 0.09 MPa absolute pressure, and atmospheric pressure for 0.5 h. The amounts of other components and process conditions in steps A2 to A5 and S2 to S4 remained the same as the key conditions fully specified in Example 1. This comparative example was used to investigate the synergistic relationship between ammonium polyphosphate and sodium tetraborate decahydrate.

[0106] Comparative Example 11: Essentially the same as Example 1, except that in step A3, the phosphorus-boron flame-retardant pre-dispersion was added to the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion in one step, and the pH was not adjusted by adding sodium hydroxide and acetic acid aqueous solutions before addition. Step A4 was still performed at 35°C, 0.09 MPa absolute pressure, and atmospheric pressure with stirring at 600 rpm for 1 hour. Step A5 was still performed at 30°C for 0.5 hours, filtered through an 80-mesh sieve, and allowed to stand for degassing for 30 minutes. The components and amounts of A and B adhesives, the mass ratio of A to B adhesives, and steps S2 to S4 remained the same as the key conditions fully listed in Example 1. This comparative example was used to examine the synergistic relationship between pH adjustment and the order of core-shell interface construction.

[0107] Characterization and performance testing: The test subjects were the bonding samples of Examples 1–4 and Comparative Examples 1–11 after curing for 7 days. The purpose was to evaluate the bonding strength of the special adhesive for thermal insulation materials to the insulation board and the substrate. The principle was to determine the failure load in a specified lap or pull-out structure and convert it into the bonding strength per unit area. The bonding strength data in Table 1 of this application were all determined according to GB / T 7124-2008 "Determination of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)". For the bonding strength test in Table 1, uniform rigid lap test samples were prepared separately. The test substrate and sample structure were consistent between the examples and comparative examples. The specific type of thermal insulation material used in the examples was not used as a variable in the bonding strength data in Table 1. The evaluation of the construction application of composite panels can be carried out with reference to GB / T 33334-2016 for single lap shear test. For each group, n=5, the mean and standard deviation of the bonding strength were recorded in MPa. The higher the value, the better the bonding performance.

[0108] The tested objects were the cured films of Examples 1–4 and Comparative Examples 1–11, with the aim of evaluating the influence of phosphorus-boron flame-retardant components and flame-retardant core-shell latex particle intermediates on flame-retardant properties. The principle was to determine the minimum oxygen concentration required for the sample to sustain combustion in an oxygen-nitrogen mixed atmosphere. The room temperature oxygen index was tested according to GB / T 2406.2-2009 "Determination of Burning Behavior by Oxygen Index Method for Plastics – Part 2: Room Temperature Test". The film thickness was controlled at 3 mm, and the film was conditioned at 23°C and 50% relative humidity for 24 hours. Each group had n=5 films. The mean and standard deviation of the limiting oxygen index were recorded, in % (%). A higher value indicates better flame-retardant performance.

[0109] The test subjects were phosphorus-boron flame-retardant pre-dispersion, flame-retardant core-shell latex particle intermediates, and samples in use after mixing A and B adhesives. The aim was to evaluate the dispersed phase particle size and structure retention after mixing. The principle was based on dynamic light scattering to detect the equivalent particle size corresponding to the Brownian motion of particles in the aqueous dispersion system. Samples were diluted with deionized water to a suitable scattering intensity range, equilibrated at 25°C for 5 minutes, and then tested. Each sample was repeated three times, and the mean and standard deviation of D50 and D90 were recorded in μm. D50 and D90 were calculated using the same dynamic light scattering intensity distribution aperture. The corresponding fields for this experiment are D50 and D90. D50 is used to characterize the median particle size of the dispersed phase, and D90 is used to compare the proportion of large-particle-size components in different samples.

[0110] The test subjects were flame-retardant core-shell latex particle intermediates and samples of the mixture of A and B glues kept in a usable state for 0.5–8 hours, with the aim of evaluating the phosphorus-boron shell structure. The principle was to observe the outer shell of the latex particles using transmission electron microscopy (TEM) frozen sections, and record the distribution of P and B elements using TEM-EDS elemental surface scanning. At least three fields of view with scales were recorded for each sample, and at least 20 latex particles were statistically analyzed. The mean shell thickness, standard deviation of shell thickness, and shell coverage were calculated.

[0111] The test subject was the centrifuged aqueous phase of flame-retardant core-shell latex particles, with the aim of evaluating the content and low migration tendency of free water-soluble phosphorus-boron salts. The principle was as follows: after centrifugation to obtain the aqueous phase, inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to determine the content of phosphorus (P) and boron (B) elements. The contents were then calculated and summed based on the mass of water-soluble phosphorus and boron salts. For each group (n=3), the mean and standard deviation of the free water-soluble phosphorus-boron salt content were recorded in wt%. Lower values ​​indicate a lower tendency for free migration of the phosphorus and boron components. This field is included in subsequent data tables.

[0112] The test subjects were adhesive A, adhesive B, and a mixed adhesive for thermal insulation materials. The purpose was to evaluate viscosity, pH value, solid content, storage redispersibility, and workability. Viscosity was tested according to GB / T 2794-2022 "Determination of Viscosity of Adhesives" using rotational viscosity testing. pH value was tested using a glass electrode pH meter according to GB / T 14518-1993 "Determination of pH Value of Adhesives". Solid content was tested according to GB / T 2793-1995 for non-volatile matter content. Each group had n=3 samples, and viscosity, pH value, solid content, workability, and storage redispersibility were recorded. The storage redispersion rate is calculated as the ratio of the dry mass of non-redispersible sediment to the total dry solid mass of the sample after storage. The calculation formula is: Storage redispersion rate = (1 - dry mass of non-redispersible sediment / total dry solid mass of sample) × 100%; where, non-redispersible sediment is the hard sediment that cannot be redispersed after the stored sample is stirred at 500 rpm for 10 min and is retained by an 80-mesh sieve. Each group has n=3, and the mean and standard deviation are recorded. The storage redispersion rate in Table 1 is calculated by combining the results of separate tests on A glue and B glue after 60 days of sealed storage at 35℃.

[0113] Figure 1 This graph shows the effect of the mass ratio of adhesive A to adhesive B on bond strength and limiting oxygen index. Figure 2 This graph shows the effect of the amount of phosphorus-boron flame retardant component in adhesive A on bond strength and limiting oxygen index. Figure 1 and Figure 2 It can be seen that in the single-factor experiments based on the basic formulation and preparation process of Example 1, after changing the mass ratio of adhesive A to adhesive B and the amount of phosphorus-boron flame retardant component in adhesive A, the adhesive strength and limiting oxygen index showed a mutually restrictive but controllable variation law. When the mass ratio of adhesive A to adhesive B is too low, the contribution of effective film-forming components and flame-retardant core-shell latex particles in the system is insufficient, and the flame retardant and adhesive properties are difficult to exert simultaneously; when the mass ratio of adhesive A to adhesive B is too high, the proportion of flame-retardant components and inorganic phases in the system increases, which easily dilutes or blocks the continuous film formation of the polymer. The results show that when the mass ratio of adhesive A to adhesive B is controlled in the range of 1:6 to 1:12, the adhesive can achieve a balance between high adhesive strength and a better limiting oxygen index. Further... Figure 2 It is evident that when the amount of phosphorus-boron flame retardant component is too low, it is difficult to provide sufficient flame retardancy; when the amount is too high, it increases the interference of the inorganic salt phase and filler phase on the continuity of latex film formation, leading to a decrease in adhesive strength. Therefore, a moderate amount of phosphorus-boron flame retardant component can improve flame resistance while maintaining interfacial adhesion. This indicates that the proposed solution, through adjusting the ratio of the two components and controlling the amount of flame retardant component, can effectively alleviate the problem of balancing adhesive strength and flame retardancy in water-based ethylene-vinyl acetate adhesive systems.

[0114] Figure 3The graph shows the effect of the mass ratio of ammonium polyphosphate to sodium tetraborate decahydrate on shell coverage and the content of free water-soluble phosphorus-boron salts. Figure 4 This is a graph showing the effect of pH value on shell coverage and bond strength in step A4. Figure 3 It can be seen that, based on the microencapsulation process of Example 1, and only changing the mass ratio of ammonium polyphosphate to sodium tetraborate decahydrate, the shell coverage and the content of free water-soluble phosphorus-boron salts do not change unidirectionally, but are jointly affected by the matching degree of the phosphorus source and boron source ratio. When the ratio deviates from the suitable range, the phosphorus-boron component is difficult to form a continuous composite shell on the outer periphery of the latex particles, and the content of free water-soluble salts increases accordingly; when the ratio is appropriate, the shell coverage increases, while the free salt content decreases, indicating that the phosphorus-boron component is more fixed at the outer interface of the latex particles. Figure 4 Furthermore, it can be seen that adjusting the pH value of the system in step A4 directly affects the shell formation process and subsequent bonding performance. Too low or too high a pH is detrimental to the stable deposition of phosphorus-boron components and the maintenance of the latex particle interface structure. Under moderate pH conditions, both shell coverage and bonding strength improve simultaneously. These results indicate that the matching ratio of ammonium polyphosphate to sodium tetraborate decahydrate and the pH control in step A4 are key factors in obtaining a stable flame-retardant core-shell latex particle intermediate. These factors can reduce the free migration of water-soluble flame-retardant components while avoiding the disruption of the bonding layer continuity caused by direct filling of the flame-retardant phase.

[0115] Figure 5 This is a differential particle size distribution map of DLS. Figure 6 This is a cumulative particle size distribution diagram of DLS. Figure 5 and Figure 6 Used to evaluate the aqueous phase stability of Example 1 and related comparative samples at the colloidal dispersion scale. Figure 5 It can be seen that the main peak of the particle size difference distribution in Example 1 is more concentrated, the main peak particle size is smaller, and the tail peak of large particle agglomeration is not obvious. This indicates that the pre-dispersion of sodium polyacrylate, the interfacial positioning of phosphorus-boron components, and the construction of latex particle shells can jointly inhibit the coarsening and aggregation of flame retardant components in the aqueous phase. Figure 6 It can be seen that the cumulative particle size distribution curve of Example 1 is steeper, the particle size growth range is narrower, and the proportion of large particles is lower, indicating that the particle size uniformity of the dispersed phase in the system is higher. This result is consistent with the process path of "pre-dispersion, then construction of core-shell latex particles, and then compounding with B-type adhesive" in this scheme, indicating that this scheme does not simply rely on the direct mixing of inorganic flame retardant components, but improves the dispersion stability of flame retardant components in water-based adhesive systems through colloidal-scale structural regulation, providing a foundation for subsequent uniform coating and continuous film formation.

[0116] Figure 7 This is a differential thickness distribution map of the shell layer in a TEM frozen section. Figure 8 This is a cumulative distribution map of the shell thickness in TEM frozen sections. Figure 9This is a scatter plot of TEM-EDS shell coverage versus mean and standard deviation. Figure 10 This is a scatter plot of the free water-soluble phosphorus-boron salt content in ICP-OES versus the standard deviation of the mean. Figure 7 and Figure 8 Further verification of the uniformity of shell thickness from the perspective of nanostructure shows that the shell thickness distribution in Example 1 is relatively narrow, with a low proportion of extremely thin shells and abnormally thick shells, indicating that the phosphorus-boron component can form a relatively continuous shell structure with a moderate thickness around the latex particles. When the shell is too thin, the fixation effect on the flame retardant component is insufficient, while when the shell is too thick, it may reduce the film continuity of the latex particles. Therefore, a moderate shell thickness is beneficial to simultaneously take into account both coating protection and colloidal dispersion. Figure 9 The results show that Example 1 has a high shell coverage and low dispersion, indicating that the P and B characteristic elements are more fully and uniformly distributed on the surface of the latex particles. Figure 10 The results show that the content of free water-soluble phosphorus-boron salts in Example 1 is low, indicating that the flame-retardant components mainly exist in the form of interfacial bonding or shell fixation, rather than being largely free in the aqueous phase. These results form a progressive support chain from "shell thickness—shell coverage—free salt content," demonstrating that this scheme can effectively locate the flame-retardant components at the nanoscale, thereby reducing the risk of later migration, precipitation, and dispersion instability.

[0117] Figure 11 This is a graph showing the change in viscosity of the mixed adhesive over time. Figure 12 To store the redistribution rate scatter plot versus mean and standard deviation. Figure 11 To evaluate the applicability of the mixture of adhesive A and adhesive B in construction, at 25°C, the viscosity increase process in Example 1 was relatively stable. In the early stage, the viscosity remained within the range suitable for coating construction, while in the later stage, a higher structural viscosity was formed, which is beneficial to maintaining the stability of the adhesive layer morphology and component distribution during the curing process. Figure 12 Further evidence shows that Example 1 still exhibits a high redispersion rate after storage, and the dispersion in repeated tests is small, indicating that the flame-retardant core-shell latex particle and filler system is not prone to irreversible sedimentation, hard agglomeration, or localized enrichment. Therefore, this solution, by adjusting the aqueous phase stability with sodium polyacrylate and combining pre-dispersion and core-shell construction processes, achieves a better connection between low-viscosity application, storage stability, and subsequent film formation, solving the problem of simultaneously achieving good dispersion stability and the tendency of flame-retardant components to migrate in water-based flame-retardant adhesives.

[0118] Figure 13 This is a scatter plot of the bond strength versus the mean and standard deviation. Figure 14 This is a scatter plot of the limiting oxygen index versus the mean and standard deviation. Figure 13 and Figure 14 The performance of Example 1 and related comparative samples was verified from the perspective of final application performance. Figure 13It can be seen that the bond strength after curing in Example 1 is high, and the dispersion of multiple test results is small, indicating that the mixing ratio of adhesive A and adhesive B, the continuous film-forming ability of latex particles, and the introduction of the flame-retardant shell layer did not significantly weaken the interfacial adhesion. Figure 14 It can be seen that the limiting oxygen index of Example 1 is higher than that of the relevant comparative samples, indicating that the phosphorus-boron composite flame retardant component can still exert an effective flame retardant effect after being fixed on the periphery of the latex particles. Combined with... Figure 13 and Figure 14 It can be seen that this solution does not simply increase the amount of flame-retardant filler to achieve flame-retardant performance, but rather achieves simultaneous improvement in bonding strength and flame-retardant performance through a division of labor structure in which latex particles undertake the bonding continuity and the phosphorus-boron shell layer undertakes the flame-retardant contribution.

[0119] Figure 15 This is a comparison of macroscopic optical photographs of the final product of Example 1 and the final product of Comparative Example 9. Figure 15 As shown in Figure a, after mixing A and B in a mass ratio of 1:6, a uniform adhesive solution was formed. The viscosity at 25°C was 300 mPa·s and the pH value was 7.0. No obvious coarse particles, flocculent lumps or phase separation were observed macroscopically at a coating amount of 1.2 kg / m², indicating that the system can still maintain good uniformity under low viscosity conditions. Figure 15 As shown in b, Comparative Example 9 did not undergo the shell-forming treatment of the flame-retardant core-shell latex particle intermediate. Instead, it directly mixed polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, calcium carbonate filler, and phosphorus-boron flame-retardant components. In this case, the macroscopic state was more prone to localized enrichment of the flame-retardant components or decreased uniformity. This comparison illustrates that the advantage of Example 1 does not solely stem from the raw materials themselves, but rather from the pre-dispersion of the flame-retardant components and the core-shell interface construction method. This method can improve the uniformity of the adhesive and the consistency of application on a macroscopic scale.

[0120] Figure 16 The image shows a comparison of the SEM morphology of the final product of Example 1 and the final product of Comparative Example 9. Figure 16 a and Figure 16 b. Comparing the overall morphology of the cured adhesive layer from a low magnification perspective, Example 1, after being coated and cured at 1.2 kg / m², can form a relatively continuous and uniform composite adhesive layer. However, in Comparative Example 9, due to the elimination of the core-shell formation process, local particle enrichment, coarse particle aggregation, or surface unevenness are more likely to occur in the cured layer. Figure 16 c and Figure 16 d Further comparison of the distribution of filler and flame retardant components under medium magnification. In Example 1, the calcium carbonate filler with D50 of 1 μm and D90 of 3 μm can be distributed more uniformly in the continuous polymer phase, while in Comparative Example 9, the inorganic components are more likely to produce local accumulation. Figure 16 e and Figure 16Under high magnification, Example 1 shows good interfacial continuity between the edges of calcium carbonate particles, the continuous polymer phase, and the local fine phase, while Comparative Example 9 is more prone to fine particle agglomeration, porosity, or interfacial discontinuities. This indicates that the flame-retardant core-shell latex particle structure not only improves the dispersion of the liquid adhesive but also further transfers this to the microstructure of the cured layer, resulting in a more uniform composite morphology in the adhesive layer.

[0121] Figure 17 This is a comparison of the TEM structures of the final product of Example 1 and the final product of Comparative Example 9. Figure 17 a and Figure 17 b shows that in Example 1, the latex particle D50 is 0.10 μm, and a phosphorus-boron shell layer with an average thickness of about 5 nm can be observed on the outer periphery of the latex particle. In contrast, the outer edge of the latex particle in Comparative Example 9 lacks a continuous shell structure, indicating that direct mixing makes it difficult to achieve stable positioning of the flame retardant component at the latex particle interface. Figure 17 c and Figure 17 d Further high-resolution TEM showed that in Example 1, the flame retardant component formed a relatively continuous interface distribution with the latex particle core phase at the nanoscale, while Comparative Example 9 showed local interface discontinuities or discrete distribution of the flame retardant salt phase. Figure 17 e and Figure 17 The TEM-EDS elemental distribution results of f further show that in Example 1, P and B elements are enriched along the outer edge of the latex particles, with a shell coverage of up to 70%, while in Comparative Example 9, P and B elements are mainly in a discrete or locally enriched state. These results support, from both nanostructure and elemental localization perspectives, that the core-shell latex particle intermediate in this scheme can achieve interfacial fixation of the flame-retardant components, thereby helping to reduce migration, aggregation, and film-forming interference caused by direct mixing.

[0122] Figure 18 This is a macroscopic optical photographic evolution diagram of the phosphorus-boron flame-retardant pre-dispersion, flame-retardant core-shell latex particle intermediate, A glue, and A / B mixed glue in Example 1. Figure 18 The results show that the dispersed phase D50 of the phosphorus-boron flame retardant predispersant liquid is 0.05 μm, D90 is 0.08 μm, the solid content is 34.5 wt%, and the viscosity is 10 mPa·s. This indicates that under the action of sodium polyacrylate, ammonium polyphosphate and sodium tetraborate decahydrate can first form a refined, low-viscosity predispersant system. Figure 18 b shows that the latex particle D50 in the flame-retardant core-shell latex particle intermediate is 0.10 μm, the shell thickness is 5 nm, and the shell coverage is 70%, indicating that the phosphorus-boron component can be further transformed from the pre-dispersed state into the latex particle surface shell structure. Figure 18 c shows that after introducing calcium carbonate fillers with D50 of 1μm and D90 of 3μm into glue A, the system still maintains macroscopic uniformity, indicating that the micron-sized fillers and core-shell latex particles can be synergistically dispersed. Figure 18The data shows that after mixing adhesive A and adhesive B at a mass ratio of 1:6, the A / B mixed adhesive still maintains a low viscosity and uniform state with a viscosity of 300 mPa·s at 25℃ and a pH value of 7.0, making it suitable for thin-coat application. Combined with... Figure 15 As shown in Figure a, the cured adhesive layer indicates that after being applied at 1.2 kg / m² and cured for 7 days at 23°C and 50% relative humidity, a continuous composite adhesive layer can be formed. The continuous evolution from the phosphorus-boron flame-retardant pre-dispersion to the A / B mixed adhesive demonstrates that this scheme achieves a complete closed-loop process, from the refined pre-dispersion of the phosphorus-boron flame-retardant components, the construction of the core-shell latex particle interface, the compounding of the A / B two components, to the final curing and film formation. This ultimately verifies the solution to the problem of synergistically achieving both adhesive strength and flame-retardant performance, as well as dispersion stability and the tendency for flame-retardant components to migrate.

[0123] Table 1 Performance of Examples and Comparative Examples

[0124] As can be seen from the performance of the examples and comparative examples in Table 1, Examples 1–4 show a relatively balanced trend in bond strength, limiting oxygen index, shell coverage, free water-soluble phosphorus-boron salt content, workability time, and storage redispersibility. In the conventional comparative examples, reduced emulsion, excessive filler, insufficient phosphorus-boron flame retardant components, deviation of shell formation temperature or time, insufficient sodium polyacrylate, deviation of the ratio of A to B adhesives, and insufficient filtration and degassing all lead to a decrease in one or more indicators. In the synergistic comparative examples, the elimination of shell formation, the absence of sodium tetraborate decahydrate, or the disruption of pH adjustment results in a decrease in shell coverage, an increase in free phosphorus-boron salt content, or a decrease in flame retardant contribution, indicating that the trend of the examples corresponds to a balance between mechanical strength and flame retardant performance, dispersion stability and low migration.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A special adhesive for thermal insulation materials, characterized in that, The special adhesive for thermal insulation materials includes adhesive A and adhesive B, with the mass ratio of adhesive A to adhesive B being 1:6 to 1:

12. The mass percentage of component A in the A-grade adhesive formula, calculated based on the total mass of components used in the preparation of A-grade adhesive, includes: 100-260 parts of polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion; 15-80 parts of filler; 5-40 parts of phosphorus-boron flame retardant component; Furthermore, the A-type adhesive contains a flame-retardant core-shell latex particle intermediate, which is formed by latex particles in the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion as the core phase and the phosphorus-boron flame-retardant component as the shell component. B-type adhesive, by weight of input, includes: 5-50 parts of polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion; Ethylene-vinyl acetate copolymer can be redispersible latex powder in quantities of 0.4-6 parts; 1-15 parts of ammonium polyphosphate; Sodium tetraborate decahydrate 0.5-8 parts; Sodium polyacrylate 0.1-10 parts; And 150-500 portions of deionized water.

2. The special adhesive for thermal insulation materials according to claim 1, characterized in that, The filler is selected from one or more of calcium carbonate, talc, and quartz powder; the phosphorus-boron flame retardant component includes ammonium polyphosphate and sodium tetraborate decahydrate, and the mass ratio of ammonium polyphosphate to sodium tetraborate decahydrate is 100:5 to 100:45; the latex particle D50 of the flame retardant core-shell latex particle intermediate is 0.10-0.80 μm, the shell thickness is 5-60 nm, and the shell coverage is 70-98%.

3. The special adhesive for thermal insulation materials according to claim 1, characterized in that, The flame-retardant core-shell latex particle intermediate is prepared by the following steps: A1. Provide phosphorus-boron flame retardant predispersant solution; A2. A polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion is provided, wherein the mass ratio of ethylene-vinyl acetate copolymer dry basis to polyvinyl alcohol dry basis in the polyvinyl alcohol-protected colloidal ethylene-vinyl acetate copolymer emulsion is 100:1 to 100:8, the solid content is 45-65 wt%, and the pH value is 4.5-6.5; A3. Based on 100 parts by weight of ethylene-vinyl acetate copolymer dry basis, add 5-35 parts by weight of the dry basis component of the phosphorus-boron flame retardant pre-dispersion to the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion described in step A2, and adjust the pH value to 7.0-8.

8. A4. Stir at 35-65℃ and normal air pressure for 1-4 hours to allow ammonium polyphosphate and sodium tetraborate decahydrate in the phosphorus-boron flame retardant predispersant to form a phosphorus-boron shell on the surface of the latex particles. A5. Aging at 30-55℃ for 0.5-2h, filtering and degassing to obtain the flame-retardant core-shell latex particle intermediate; The flame-retardant core-shell latex particle intermediate obtained after steps A4-A5 has a pH value of 7.0-8.8, a solid content of 35-60 wt%, a latex particle D50 of 0.10-0.80 μm, a shell thickness of 5-60 nm, a shell coverage of 70-98%, and a free water-soluble phosphorus-boron salt content of 0.5-20 wt%.

4. The special adhesive for thermal insulation materials according to claim 3, characterized in that, The phosphorus-boron flame retardant predispersant solution in step A1 is prepared by the following steps: B1. Add 100 parts by weight of ammonium polyphosphate, 5-45 parts by weight of sodium tetraborate decahydrate, 0.5-6 parts by weight of sodium polyacrylate and 200-600 parts by weight of deionized water into a dispersion container; B2. Adjust the pH value to 7.5-9.0; B3. Stir at 20-45℃ and normal air pressure for 0.5-2 hours to obtain the phosphorus-boron flame retardant pre-dispersion; B4. The phosphorus-boron flame retardant predispersant has a solid content of 15-43 wt%, a viscosity of 10-800 mPa·s at 25°C, a D50 of 0.05-0.10 μm for the dispersed phase, and a pH of 7.5-9.

0.

5. The special adhesive for thermal insulation materials according to claim 1, characterized in that, The polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsions in adhesives A and B meet the following conditions: The dry basis content of ethylene-vinyl acetate copolymer is 45-65 wt%; The content of polyvinyl alcohol relative to the dry basis of ethylene-vinyl acetate copolymer is 1-8 wt%; The viscosity at 25℃ is 500-4500 mPa·s; pH value is 4.5-6.5; The D50 of latex particles is 0.08-0.60 μm.

6. The special adhesive for thermal insulation materials according to claim 1, characterized in that, The ethylene-vinyl acetate copolymer redispersible latex powder in the B-type adhesive contains ethylene-vinyl acetate copolymer and polyvinyl alcohol, wherein the mass ratio of ethylene-vinyl acetate copolymer to polyvinyl alcohol is 100:2 to 100:

15.

7. The special adhesive for thermal insulation materials according to claim 1, characterized in that, The packing material has a D50 of 1-10 μm and a D90 of 3-25 μm.

8. A method for preparing a special adhesive for thermal insulation materials as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Provides flame-retardant core-shell latex particle intermediates; S2. Preparation of A-adhesive: According to the feeding components and dosage of A-adhesive in the special adhesive for thermal insulation materials, the flame-retardant core-shell latex particle intermediate described in step S1 is mixed with the remaining feeding components of A-adhesive to obtain A-adhesive; S3. Preparation of B adhesive: According to the ingredients and dosage of B adhesive in the special adhesive for thermal insulation materials, mix the ingredients of B adhesive to obtain B adhesive; S4. Before use, mix the A glue and the B glue according to the mass ratio of A glue to B glue in the special adhesive for thermal insulation materials to obtain the special adhesive for thermal insulation materials.

9. The method according to claim 8, characterized in that, In step S2, the filler is first mixed with a portion of the polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, and then the flame-retardant core-shell latex particle intermediate described in step S1 is added to obtain adhesive A. In step S3, sodium polyacrylate is first dissolved in deionized water, and then polyvinyl alcohol protective colloidal ethylene-vinyl acetate copolymer emulsion, ethylene-vinyl acetate copolymer redispersible latex powder, ammonium polyphosphate and sodium tetraborate decahydrate are added in sequence to obtain glue B. In step S4, the construction time after mixing adhesive A and adhesive B is 0.5-8 hours.

10. A method for using a special adhesive for thermal insulation materials, characterized in that, Includes the following steps: Before use, mix the A and B components in the thermal insulation material adhesive according to any one of claims 1-7 to obtain an application-ready adhesive solution. Within a construction time of 0.5-8 hours, the construction adhesive is applied to the surface of the insulation material and / or the surface of the substrate to be bonded by scraping, rolling, brushing, spraying or dot-and-frame application. The thermal insulation material is adhered to and compacted with the substrate to be bonded. After curing, it forms an adhesive layer with flame-retardant properties.

Images