Chapter 6

What Is Flexible Stone: Material Definition, Microstructure, and Formulation System

Compiled by Guangdong Fortune Stone New Material Co., Ltd.

Key Points

• Flexible stone is neither traditional ceramic, coating, nor plastic, but a particle-reinforced composite flexible facing material with a polymer as the continuous phase and inorganic non-metallic material as the dispersed phase. Its corresponding material standard name is “modified inorganic powder composite building facing sheet.”
• Its performance foundation comes from three major engineering essentials: at the micro level, constructing a “hard core, soft shell” structure; in formulation, the synergy of four components—polymer, inorganic filler, functional additives, and water; in process, adopting “bottom heating, top moisture extraction, rear return air” to balance production capacity and performance stability.
• This chapter provides four key formulas for describing modulus prediction, soft shell layer proportion, interfacial bonding, and composite glass transition temperature, laying a quantitative foundation for flexible stone material design and performance regulation.

6.1 Material Definition and Classification Status of Flexible Stone

6.1.1 Material Definition

According to current industry standards, the standard name of flexible stone is modified inorganic powder composite building facing sheet, commonly known as flexible stone. It is a flexible inorganic-organic composite building facing sheet made from modified inorganic non-metallic sand powder (such as calcium powder and calcium sand) as the dispersed phase and polymer as the continuous phase, through batching, forming, and drying. The industry commonly refers to it as MCM (Flexible Ceramic Material).

In material taxonomy, flexible stone belongs to polymer matrix composites, specifically particle-reinforced polymer matrix composites. Its reinforcement phase is modified inorganic non-metallic sand powder, and its matrix phase is modified acrylate copolymer emulsion. Its microstructural characteristic is that the surface of inorganic filler particles is wrapped with a polymer layer, forming a “hard core, soft shell” structure. Its macroscopic performance characteristics are: both the texture and durability of ceramic and the flexibility and lightness of polymer materials.

Table 6-1 Taxonomic Comparison of Flexible Stone and Traditional Materials

6.1.2 Classification Status

In the building materials classification system, flexible stone occupies a unique position. It does not fall under the jurisdiction of traditional ceramic products, nor under building coatings, nor under plastic products. It belongs to the emerging category of flexible facing materials, with product standards JG/T 311 Flexible Facing Brick and JC/T 2219 Modified Inorganic Powder Composite Building Facing Sheet.

The establishment of this classification status reflects the process of material generational replacement. When traditional material classification systems cannot encompass new materials, new standard categories emerge. The standard category of flexible stone has grown from nothing, marking that this material has moved from a “laboratory concept” to an “engineering material.”

6.2 Microstructure of Flexible Stone: The Hard Core, Soft Shell Model

6.2.1 Basic Characteristics of Microstructure

The microstructural design of flexible stone is the core of its distinction from traditional materials. Its core concept is the hard core, soft shell structure.

The microstructure of traditional ceramics is “hard against hard”—inorganic crystal particles are in direct contact, forming a rigid skeleton through high-temperature sintering. The advantages of this structure are high hardness and good durability, but the disadvantage is high brittleness; once subjected to impact or deformation, stress cannot be dispersed, and cracking is easy.

The microstructure of flexible stone is “hard core, soft shell”—the surface of each inorganic filler particle (hard core) is wrapped with a layer of polymer (soft shell). When the material is subjected to external force, the soft shell layer can undergo elastic deformation, absorbing and dispersing stress, thereby avoiding direct collision between hard cores and crack propagation.

6.2.2 Three Key Parameters of the Hard Core, Soft Shell Structure

The performance of the hard core, soft shell structure depends on three key parameters: the volume fraction of the hard core, the thickness of the soft shell layer, and the strength of interfacial bonding.

Parameter one: Relationship between hard core volume fraction and modulus. The higher the hard core volume fraction, the higher the material modulus, but the flexibility decreases. The goal of flexible stone formulation design is to maximize filler volume fraction while maintaining sufficient flexibility, to obtain ceramic-like texture and hardness. The relationship between filler volume fraction and composite elastic modulus can be described by the Halpin-Tsai equation.

$E_c=E_m\frac{1+\xi \eta V_f}{1-\eta V_f}$Ec​=Em​1−ηVf​1+ξηVf​​

Where Ec is the composite modulus, Em is the matrix modulus, Vf is the filler volume fraction, ξ is the filler shape factor, η is the modulus ratio factor, η = (Ef – Em) / (Ef + ξEm), and Ef is the filler modulus. The numerator of η is the modulus difference between filler and matrix, and the denominator is the filler modulus plus the shape factor correction term; when Ef > Em, η > 0, the filler plays a reinforcing role; when Ef = Em, η = 0, the composite modulus equals the matrix modulus.

Parameter two: Relationship between soft shell layer thickness and stress dispersion. If the soft shell layer is too thin, the stress dispersion effect is poor, and the material is brittle; if the soft shell layer is too thick, the hardness and wear resistance of the material decrease, and the texture deteriorates. The ratio of soft shell layer thickness ts to filler particle size dp determines the volume fraction of the interfacial phase, and the relationship is:

$V_s=\frac{6t_s}{d_p}{V}_f$Vs​=dp​6ts​​Vf​

Where Vs is the interfacial phase volume fraction, ts is the soft shell layer thickness, dp is the filler particle size, and Vf is the filler volume fraction. The goal of flexible stone formulation design is to control Vs within the range of 15%–25% to achieve a balance between hardness and toughness.

Parameter three: Relationship between interfacial bonding strength and macroscopic performance. Interfacial bonding strength is the “lifeblood” of flexible stone performance. If interfacial bonding is weak, the material is prone to delamination, peeling, and detachment; if interfacial bonding is strong, the material can achieve “flexible but not scattered, hard but not brittle.” The relationship between interfacial bonding strength and composite tensile strength can be described by the modified Kelly-Tyson model.

Modified Kelly-Tyson model. The relationship between interfacial bonding strength τ and composite tensile strength σc can be described by the modified Kelly-Tyson model. This model decomposes composite strength into three parts: subcritical filler contribution (interfacial debonding control), supercritical filler contribution (filler fracture control), and matrix contribution. For the flexible stone system, the equivalent particle size of inorganic fillers is much smaller than the critical length Lc, so the first term (subcritical contribution) dominates, namely:

${\sigma }_c\approx {\eta }_0{\sum }_{L_i<L_c}\frac{\tau \cdot L_i\cdot V_i}{d}+(1-V_f){\sigma }_m^{\ast }$σc​≈η0​∑Li​<Lc​​dτ⋅Li​⋅Vi​​+(1−Vf​)σm∗​

This equation shows that the higher the interfacial shear strength τ, the greater the composite tensile strength. This quantitatively explains that “interfacial bonding strength is the lifeblood of flexible stone performance”—a decrease in τ will directly lead to a decrease in σc. In flexible stone formulation design, τ is regulated through coupling agent treatment, reactive emulsifier technology, and other means.

Modified Kelly-Tyson model. This formula expresses the quantitative relationship between interfacial bonding strength τi and composite tensile strength σc; the specific expanded form is expressed according to the composite interface mechanics standard.

6.2.3 Decisive Influence of the Hard Core, Soft Shell Structure on Macroscopic Performance

Table 6-2 Influence of Microstructural Parameters on Macroscopic Performance

6.3 Formulation System of Flexible Stone: Four-Component Synergy Model

6.3.1 Overview of the Formulation System

The formulation system of flexible stone consists of four types of components: polymer matrix (continuous phase), inorganic non-metallic filler (dispersed phase), functional additives (regulating phase), and water (processing medium). The synergy of these four types of components determines the final performance of flexible stone.

Table 6-3 Four Components of the Flexible Stone Formulation System and Their Functions

6.3.2 Component One: Polymer (Continuous Phase)

Polymer is the “soul” of flexible stone, determining the material’s flexibility, water resistance, weather resistance, and bonding strength. The mainstream material currently used in the industry is modified acrylate emulsion, with four core performance indicators.

Indicator one: Glass transition temperature (Tg). Tg determines the material’s flexibility at low temperatures and hardness at high temperatures. If Tg is too low, the material is soft at high temperatures; if Tg is too high, the material is brittle at low temperatures. Flexible stone formulations usually adopt composite Tg design, achieving wide-temperature-range performance balance through the blending of emulsions with different Tg values. The calculation of composite Tg can be described by the Fox equation.

$\frac{1}{T_g}={\sum }_i\frac{w_i}{T_{g,i}}$Tg​1​=∑i​Tg,i​wi​​

Where wi is the mass fraction of component i, and Tgi is the glass transition temperature of component i.

Indicator two: Minimum film-forming temperature (MFFT). MFFT determines the film-forming performance of the material during construction and drying. If MFFT is too high, the material is difficult to form a film at low temperatures; if MFFT is too low, the initial water resistance of the material is poor. Flexible stone formulations usually control MFFT within the range of 5–15°C.

Indicator three: Solid content. Solid content determines the bonding strength and film thickness of the emulsion. If solid content is too low, bonding strength is insufficient; if solid content is too high, emulsion viscosity is high, and construction is difficult. Flexible stone formulations usually control solid content within the range of 45%–55%.

Indicator four: Core-shell emulsion design. In emulsion design, the “hard core, soft shell” core-shell structure emulsion approach is adopted: the core of core-shell latex particles is harder (providing hardness), and the shell is softer (providing flexibility), thereby achieving unity of hardness and toughness at the formulation level. Core-shell emulsion preparation usually adopts a two-stage seeded emulsion polymerization method: the first stage prepares the hard core, with Tg controlled at 50–70°C; the second stage coats the soft shell on the hard core surface, with Tg controlled at -10–10°C.

Table 6-4 Core-Shell Emulsion Design Parameters

Patent technology support for emulsion formulas. Around emulsion formulas, Guangdong Fortune Stone New Material Co., Ltd. has formed a complete patent chain covering “breathability—non-migration—high flexibility—topcoat function.” Four patents address key technical challenges of flexible stone emulsions in different application scenarios from different dimensions.

In terms of balancing breathability and flexibility, the patent “A Large-Particle-Size High-Permeability Flexible Stone Special Emulsion and Its Preparation Method and Application” (Application No.: CN202511656186.0) addresses the ratio of filler particle size to interfacial phase volume fraction. Through large-particle-size design, it increases the ratio of soft shell thickness to filler particle size, controlling the interfacial phase volume fraction within the optimal range of 15%–25%, achieving a balance between breathability and flexibility. This patent uses polyether-polyester block reactive toughening agent and phosphorus-nitrogen benzisothiazolinone derivative antibacterial flame retardant as core functional additives, solving the industry problems of conventional formulas being prone to brittle cracking at low temperatures and poor breathability.

In terms of interface stability, the patent “Non-Migratory Flexible Stone Emulsion Based on Reactive Emulsifiers and Its Preparation Method and Application” (Application No.: CN202610057003.1) uses reactive emulsifiers, bonding emulsifier molecules to polymer particle surfaces through covalent bonds, making them part of the polymer and fundamentally avoiding emulsifier desorption from polymer particles or migration in latex films. This technology eliminates defects such as surface skinning, mold sticking, and water resistance degradation caused by small molecule migration, significantly improving emulsion stability, coating gloss, drying speed, film-forming performance, and coating water resistance.

In terms of wide-temperature-range durability, the patent “A High-Flexibility Emulsion and Its Preparation Method and Application in Flexible Stone” (Application No.: CN202610376325.2) uses monomer pre-emulsification semi-continuous seed emulsion polymerization, introducing modified additive A (prepared by reacting epoxidized cashew nut shell liquid with mercapto compounds) and modified additive B (prepared by reacting carboxybenzotriazole with epoxysilane) into the core-shell structure, achieving excellent flexibility of flexible stone at -30°C, withstanding 100 freeze-thaw cycles without cracking or peeling, and weather resistance of 3500h. This patent regulates the Tg and crosslinking degree of the core-shell structure from the molecular level, fundamentally improving the wide-temperature-range performance of flexible stone.

In terms of surface weather and stain resistance, the patent “Inorganic Silicone Resin Modified Acrylic Emulsion for Flexible Stone Topcoat and Its Preparation Method” (Application No.: CN202610033529.6) copolymerizes inorganic silicone resin with acrylate monomers through chemical bonding, combining the weather resistance and stain resistance of inorganic silicone resin with the flexibility and bonding properties of acrylate. This patent enables the flexible stone topcoat layer to achieve stain resistance (whiteness recovery rate) of over 80% and weather resistance of 3500h.

The above four patent technologies support the “light, tough, and durable” performance advantages of flexible stone from different dimensions of emulsion formulas. In Chapter 7 Performance Indicator System, Chapter 10 Carbon Footprint and Green Value, Chapter 13 Technological Evolution and Product Innovation, and Chapter 15 System Solutions, these patent technologies will repeatedly appear as technical support.

6.3.3 Component Two: Inorganic Filler (Dispersed Phase)

Inorganic filler is the “skeleton” of flexible stone, determining the material’s texture, hardness, wear resistance, and weather resistance. Commonly used inorganic fillers include natural colored sand, quartz powder, mineral powder, and functional fillers.

Filler particle size distribution. The particle size of fillers directly affects the density and surface texture of flexible stone. Ideal particle size grading is the proportional combination of coarse, fine, and ultrafine particles, optimizing continuous particle size distribution to achieve maximum packing density, thereby obtaining dense structure and uniform strength.

Table 6-5 Filler Particle Size Grading Design

Filler surface modification. Filler surface modification is a key means of improving interfacial bonding strength. There are four commonly used surface modification methods: silane coupling agent treatment, forming an organosilane coupling layer on the surface of inorganic fillers to enhance chemical bonding with polymers, suitable for quartz powder and mica powder; titanate coupling agent treatment, forming an organic monomolecular layer to improve dispersibility, suitable for calcium carbonate and talc powder; surface grafting, chemically grafting polymer chains onto filler surfaces to achieve strong interfacial bonding, suitable for nano fillers; physical coating, surface adsorption coating to improve compatibility, suitable for various fillers.

Table 6-6 Comparison of Filler Surface Modification Methods

6.3.4 Component Three: Functional Additives (Regulating Phase)

Additives are the “seasoning” of flexible stone; the dosage is small but the role is critical. Common additives include dispersants, defoamers, thickeners, film-forming aids, preservatives, flame retardants, and UV absorbers.

Table 6-7 Types and Functions of Functional Additives

6.3.5 Component Four: Water (Processing Medium)

Water is the dispersion medium in the flexible stone production process, volatilized through drying after material forming. The amount of water and volatilization rate directly affect the forming quality and production efficiency of the material. Residual moisture in flexible stone products is usually controlled below 2%.

6.4 Forming Process of Flexible Stone: Bottom Heating, Top Moisture Extraction, Rear Return Air

6.4.1 Forming Process Route

The forming process of flexible stone is a key link determining product quality and production efficiency. Common industry process routes include scraping, roller coating, and spraying, but regardless of the route, the core lies in the drying process—how to quickly and evenly remove moisture without damaging material performance.

6.4.2 Technical Principles of the Drying Process

In the drying process, an effective method can be summarized as “bottom heating, top moisture extraction, rear return air.” The technical principles of this process are as follows.

Principle one: Bottom heating. Heat is transferred from below, causing moisture to migrate from the interior of the material to the surface. The advantages of this heating method are: uniform heat, not easy to cause surface skinning; reasonable moisture migration path, high drying efficiency. The temperature field distribution can be described by the heat conduction equation.

$\frac{\mathrm{\partial }T}{\mathrm{\partial }t}=\alpha (\frac{{\mathrm{\partial }}^{2}T}{\mathrm{\partial }{x}^2}+\frac{{\mathrm{\partial }}^{2}T}{\mathrm{\partial }{y}^2}+\frac{{\mathrm{\partial }}^{2}T}{\mathrm{\partial }{z}^2})$∂t∂T​=α(∂x2∂2T​+∂y2∂2T​+∂z2∂2T​)

Where T is temperature, t is time, and α is thermal diffusivity. The bottom heating method makes the temperature gradient consistent with the moisture migration direction, facilitating moisture migration from the interior to the surface.

Principle two: Top moisture extraction. A moisture extraction system is set at the top of the drying chamber to promptly discharge evaporated water vapor. This avoids the inhibition of drying speed by high humidity environments and prevents water vapor from condensing on the material surface. The moisture evaporation rate can be described by the mass transfer equation.

$\frac{dm}{dt}=k\cdot A\cdot (P_s-P_v)$dtdm​=k⋅A⋅(Ps​−Pv​)

Where m is moisture mass, t is time, k is mass transfer coefficient, A is evaporation area, Ps is surface vapor pressure, and PV is environmental vapor pressure. Top moisture extraction reduces PV, thereby increasing the evaporation rate.

Principle three: Rear return air. A return air system is set at the rear section of the drying chamber to recycle part of the hot air. This saves energy and makes the temperature and humidity distribution in the drying chamber more uniform. The energy recovery efficiency can be described by the following equation.

$\eta =\frac{Q_{recovered}}{Q_{total}}\times 100\mathrm{\%}$η=Qtotal​Qrecovered​​×100%

Where Qrecovered is recovered heat and Qtotal is total heat. The rear return air design can increase energy recovery efficiency to 30%–50%.

6.4.3 Influence of Drying Process Parameters on Product Performance

Table 6-8 Influence of Drying Process Parameters on Product Performance

6.4.4 Practical Effects of Process Innovation

The practical effects of the “bottom heating, top moisture extraction, rear return air” process are: flexible stone single-line daily production capacity has increased from the industry’s common 400–800 m² to 800–1,000 m², while product qualification rate and performance stability have also significantly improved.

Table 6-9 Comparison Before and After Process Innovation

The value of process innovation is reflected not only in the improvement of production capacity and qualification rate but also in the assurance of flexible stone performance stability. The non-migratory emulsion patent (Application No.: CN202610057003.1), through reactive emulsifier technology, eliminates defects such as surface skinning and mold sticking caused by small molecule migration, increasing production qualification rate from 85%–90% to 95%–98%, forming a synergistic effect with drying process innovation. The -30°C flexibility and 100 freeze-thaw cycle performance of the high-flexibility emulsion patent (Application No.: CN202610376325.2) also depend to a large extent on the stable curing of the core-shell structure by the drying process—only when drying process parameters are precisely controllable can the core-shell structure maintain its designed state after film formation, and wide-temperature-range performance be fully utilized.

6.5 Macroscopic Performance of Flexible Stone: Three Numbers and One Table

6.5.1 Three Core Numbers

The macroscopic performance of flexible stone can be summarized in three numbers.

Number one: Self-weight 3–5 kg/m². About one-tenth of traditional ceramic tiles and one-twentieth of dry-hanging stone. This means flexible stone hardly increases the load burden on building structures, giving it a natural advantage in facade retrofit scenarios.

Number two: Thickness 3–5 mm. The finished thickness of flexible stone usually does not exceed 5 mm, does not increase the building facade thickness, and does not affect door and window opening or building outline.

Number three: Bending radius up to 20 mm. Flexible stone can fit complex shapes such as cylinders, curved surfaces, and corners, providing architects with greater creative freedom.

6.5.2 Performance Comparison Table

Table 6-10 Performance Comparison Between Flexible Stone and Traditional Ceramic Tiles

This table clearly shows the performance differences between flexible stone and traditional ceramic tiles: in durability indicators, flexible stone is equivalent to traditional ceramic tiles; in self-weight, thickness, and construction method, flexible stone has significant advantages. Among them, the “high-flexibility emulsion up to 3500h” in the artificial weathering resistance indicator comes from the technological breakthrough of the patent “A High-Flexibility Emulsion and Its Preparation Method and Application in Flexible Stone” (Application No.: CN202610376325.2)—this patent, through the introduction of modified additive A and modified additive B, regulates the Tg and crosslinking degree of the core-shell structure, increasing flexible stone’s weather resistance from the industry’s common 2000h to 3500h. The “no abnormality after 100 cycles” in freeze-thaw resistance also comes from the support of this patent technology.

6.6 Where Does Flexible Stone’s “Ceramic Texture” Come From

6.6.1 Micro-Design of Surface Texture

Many people who first encounter flexible stone ask a question: flexible stone looks like ceramic and feels like ceramic, but it is clearly not ceramic. Where does this “ceramic texture” come from?

The answer lies in the micro-design of surface texture. The surface texture of flexible stone is not simple flat printing, but through mold pressing or texture transfer, forming a microscopic concave-convex structure on the material surface. These concave-convex structures simulate the crystal particles of natural stone, the glaze luster of ceramic, and the rough texture of brick walls, achieving a “fake but real” effect in vision and touch.

6.6.2 Integral Coloring Technology

More importantly, the color of flexible stone is not a surface coating but integral coloring—pigments are uniformly distributed throughout the entire cross-section of the material. This means that even if the surface is slightly worn or scratched, the exposed new surface still maintains the same color, without “fading” or “showing white.”

This “integral coloring” characteristic is an important advantage of flexible stone over coatings and printed facing—the color of coatings is only a surface coating, and once worn, the base is exposed; the color of flexible stone is “grown into” the material.

6.7 Product Category System of Flexible Stone

Flexible stone is not a single product but a category system. According to different application scenarios and performance requirements, flexible stone can be divided into multiple sub-categories.

Table 6-11 Flexible Stone Product Category System

In facade retrofit exterior wall scenarios, we focus on exterior wall flexible stone. But understanding the entire category system helps establish a complete understanding of flexible stone. It should be particularly emphasized: interior wall flexible stone cannot be used for exterior walls—the performance standards of the two are completely different. Low-priced interior-grade products passed off as exterior wall products are behavior that must be rejected in facade retrofit projects.

6.8 Decision Reference for Facade Retrofit Offices

Key Decision Points of This Chapter

• Flexible stone is a flexible facing material with polymer as the continuous phase and inorganic non-metallic material as the dispersed phase, with self-weight only 3–5 kg/m² and thickness 3–5 mm. In facade retrofit exterior wall material selection, it can be a priority option for reducing structural load and lowering removal volume.
• To judge flexible stone quality, at the micro level, attention should be paid to whether the “hard core, soft shell” structure is established; at the macro level, attention should be paid to key indicators such as bending radius, water absorption, freeze-thaw resistance, and bonding strength, not just surface texture and color.
• Whether flexible stone can be used in a specific facade retrofit project should be based on sample wall measured data, not solely on product brochures or oral promises.

Compliance Check Items

1. Verify whether the product complies with JG/T 311 Flexible Facing Brick and JC/T 2219 Modified Inorganic Powder Composite Building Facing Sheet standards, and verify the type inspection report.
2. Verify whether the fire rating meets the requirements for building height and densely populated places (high-rise buildings should reach A2, ordinary residential B1).
3. Verify the consistency of incoming product thickness, surface density, flexibility, and other indicators with test reports; interior wall flexible stone must not be used for exterior walls.
4. Verify substrate moisture content, flatness, and bonding agent compatibility; make sample walls and conduct pull-off tests according to system standard requirements first.

Cost Reference Range

1. Flexible stone material unit prices vary significantly depending on formula system, fire rating, and surface function; specific costs are based on project procurement prices; 30-year life cycle cost comparison is detailed in Chapter 12.
2. Using flexible stone for facade retrofit can reduce costs for wall removal, cleaning, and structural reinforcement, but supporting costs such as substrate repair, special bonding agents, and topcoat protection must be included in the total cost.

Risk Warnings

1. Blindly pursuing low prices may result in purchasing interior-grade or low-performance products, posing hollowing, fading, and detachment risks when used on facade retrofit exterior walls.
2. Substrate moisture content exceeding standards or incompatible bonding agents are the main hidden dangers of flexible stone hollowing and detachment in facade retrofit and should be listed as key control items.
3. The “ceramic texture” of flexible stone depends on integral coloring and surface texture processes; low-priced products may have appearance defects such as color difference and exposed base.

Replicability Judgment

1. Flexible stone is lightweight, flexible, and convenient to construct, with good replicability in facade retrofit exterior wall renovation.
2. Before promotion, material test report verification, sample wall pull-off tests, and construction process briefings should be completed, and batch application should proceed only after confirming substrate conditions are qualified.
3. In northern freeze-thaw regions and areas with strong ultraviolet radiation, freeze-thaw cycle times and weathering resistance indicators should be verified respectively before promotion.

Reflections on Stone, Insights on Fortune

Flexible stone is not a “material”; it is a “system.” Behind every performance number stands a complete engineering system from molecular design to formula blending, from drying processes to interface regulation. Looking at any single component alone cannot understand flexible stone; only by connecting the four components, hard core soft shell, interface, and process into a complete chain can one truly understand flexible stone.

References

[1] Ministry of Housing and Urban-Rural Development. JG/T 311-2011 Flexible Facing Brick[S]. Beijing: Standards Press of China, 2011.

[2] Ministry of Industry and Information Technology. JC/T 2219-2014 Modified Inorganic Powder Composite Building Facing Sheet[S]. Beijing: China Building Materials Industry Press, 2014.

[3] Ministry of Housing and Urban-Rural Development. GB 8624-2012 Classification for Burning Behavior of Building Materials and Products[S]. Beijing: Standards Press of China, 2012.

[4] Halpin J C, Kardos J L. The Halpin-Tsai equations: A review[J]. Polymer Engineering & Science, 1976, 16(5): 344-352.

[5] Kelly A, Tyson W R. Tensile properties of fibre-reinforced metals: Copper/tungsten and copper/molybdenum[J]. Journal of the Mechanics and Physics of Solids, 1965, 13(6): 329-350.

[6] Fox T G, Flory P J. Second-order transition temperatures and related properties of polystyrene. I. Influence of molecular weight[J]. Journal of Applied Physics, 1950, 21(6): 581-591.

[7] National Intellectual Property Administration. A Large-Particle-Size High-Permeability Flexible Stone Special Emulsion and Its Preparation Method and Application: Guangdong Fortune Stone New Material Co., Ltd.[P]. Application No.: CN202511656186.0.

[8] National Intellectual Property Administration. Non-Migratory Flexible Stone Emulsion Based on Reactive Emulsifiers and Its Preparation Method and Application: Guangdong Fortune Stone New Material Co., Ltd.[P]. Application No.: CN202610057003.1.

[9] National Intellectual Property Administration. A High-Flexibility Emulsion and Its Preparation Method and Application in Flexible Stone: Guangdong Fortune Stone New Material Co., Ltd.[P]. Application No.: CN202610376325.2.

[10] National Intellectual Property Administration. Inorganic Silicone Resin Modified Acrylic Emulsion for Flexible Stone Topcoat and Its Preparation Method: Guangdong Fortune Stone New Material Co., Ltd.[P]. Application No.: CN202610033529.6.