Stone plastic composite floor and preparation method thereof

Abstract

The application belongs to the field of composite board manufacturing, and particularly relates to a stone-plastic composite floor and a preparation method thereof. The method comprises the following steps: 1) placing nano-alloy powder in a pretreatment liquid to perform heat ultrasonic modification treatment, and obtaining modified nano-alloy powder; 2) crushing calcareous dolomite into micro powder, and then premixing and blending the micro powder with an oily plasticizer to obtain a compound slurry; 3) mixing PVC resin, a lubricant and the modified nano-alloy powder to perform low-temperature dry mixing, then adding the compound slurry and a stabilizer to perform warm premixing, and then adding a crosslinking agent to perform high-temperature mixing, and obtaining a mixture; 4) adding a foaming agent to the mixture to perform final mixing, and then performing post-pressing, forming and gradient heat pressing to obtain the stone-plastic composite floor. The application excites multiple synergies through fillers, constructs multiple network structures, improves the dispersion uniformity of the fillers, comprehensively optimizes and improves the mechanical properties and sound insulation and heat insulation properties of the calcium-based stone powder stone-plastic composite floor, and realizes performance upgrading of a low-cost product.

Description

Technical Field

[0001] This invention belongs to the field of composite board manufacturing, and particularly relates to a stone-plastic composite floor and its preparation method. Background Technology

[0002] Stone Plastic Composite (SPC) flooring is a new type of environmentally friendly building material that uses stone powder as the main filler and thermoplastic polymer materials such as PVC as the matrix. It combines the stability of stone with the processability of plastic, and can simulate the texture and pattern of stone flooring to a certain extent. Therefore, it is widely used in the floor decoration of residential, commercial spaces and public places.

[0003] Based on the differences in the composition of stone powder fillers, current stone-plastic composite flooring is mainly divided into silicon-based stone powder stone-plastic composite flooring, which is mainly composed of silicate minerals, and calcium-based stone powder stone-plastic composite flooring, which is mainly composed of calcium carbonate minerals. These two types of stone-plastic composite flooring show significant differences in performance and economy.

[0004] Silicon-based stone powder stone-plastic composite flooring boasts significant advantages in several aspects, such as wear resistance, heat insulation, and various strength indicators. Furthermore, the interface between calcium carbonate and PVC is clear, and the bonding is relatively limited, making it prone to detachment. Therefore, most performance characteristics of silicon-based stone powder stone-plastic composite flooring are far superior to those of calcium-based stone powder stone-plastic composite flooring. However, calcium carbonate minerals are widely available, and their cost is often less than half or even lower than that of silicate minerals. They are also easier to process and require fewer additives, resulting in a significantly lower production cost compared to silicon-based stone powder stone-plastic composite flooring, offering a substantial cost-performance advantage. Due to its outstanding cost and environmental advantages, calcium-based stone powder stone-plastic composite flooring remains one of the mainstream products in the market.

[0005] However, its performance defects cannot be ignored. Therefore, in recent years, there has been much research on calcium-based stone powder stone-plastic composite flooring. In addition to improving the matrix composition, most research focuses on metal / metal oxide reinforcement. In this regard, there are actually three main research directions. The first is metal oxide coating reinforcement, such as coating the wear-resistant layer with aluminum oxide or titanium oxide nanoparticle coatings to improve surface hardness and scratch resistance. However, such coatings are prone to peeling due to insufficient interfacial bonding. At the same time, the introduction of some precious metals and / or precious metal oxides will also weaken or even completely eliminate its cost advantage. The second is metal fiber reinforcement, which involves adding stainless steel or aluminum fibers to the substrate layer and improving impact resistance through mechanical interlocking. However, metal fibers have poor compatibility with the PVC matrix, which can easily cause interfacial stress concentration and lead to interlayer delamination. The third is to further add metal powder fillers to the stone powder filler, such as mixing copper powder or iron powder with stone powder, using the thermal conductivity of metal to improve the heat dissipation performance of the floor. However, it also has similar problems to metal fibers, which can easily cause interfacial stress concentration and lead to interlayer delamination.

[0006] It is evident that the main problems currently faced by metal / metal oxide-reinforced SPC flooring are issues of dispersion and bonding. Furthermore, metal / metal oxides often increase the brittleness of SPC flooring. In addition, due to the mismatch between the thermal expansion coefficients of some metal / metal oxides and the matrix, cracking is prone to occur in areas with large annual temperature differences or short-term temperature fluctuations. Therefore, metal / metal oxide-reinforced calcium-based stone powder SPC flooring still has many problems that urgently need to be solved. Summary of the Invention

[0007] To address the numerous performance defects of existing calcium-based stone powder stone-plastic composite flooring, and the fact that current research on strengthening calcium-based stone powder stone-plastic composite flooring has encountered some bottlenecks and misconceptions, leading to weakened cost advantages or performance imbalances, and even the generation of new performance defects, this invention provides a calcium-based stone powder stone-plastic composite flooring and a method for preparing the stone-plastic composite flooring.

[0008] The main objective of this invention is:

[0009] 1. By using special processing and additive methods, the strengthening effect of metal-based materials on stone-plastic composite flooring is altered;

[0010] II. The mechanical properties of stone-plastic composite flooring are comprehensively improved through the synergistic combination of multiple components;

[0011] Third, construct a specific microstructure system to weaken the negative effects of metal-based materials on stone-plastic composite flooring.

[0012] To achieve the above objectives, the present invention adopts the following technical solution.

[0013] A method for preparing stone-plastic composite flooring.

[0014] The method includes:

[0015] 1) The nano-alloy powder was placed in a pretreatment solution and subjected to thermal ultrasonic modification to obtain modified nano-alloy powder;

[0016] 2) Crush the calcareous dolomite into micro powder, and then premix it with an oily plasticizer to form a compound slurry;

[0017] 3) Mix PVC resin, lubricant and modified nano-alloy powder at low temperature, then add compound slurry and stabilizer for premixing at high temperature, and then add crosslinking agent for high temperature kneading to obtain the mixture.

[0018] 4) Add foaming agent to the mixture and then press it into sheets to obtain pre-boards. Perform gradient hot pressing on the pre-boards to obtain stone-plastic composite flooring.

[0019] As a preferred option

[0020] The nano-alloy powder mentioned in step 1) is CSZ532 alloy powder with a mesh size ≥ 300 mesh;

[0021] Step 1) The pretreatment solution is a KH550-ethanol solution with a KH550 concentration of 1-3 wt%.

[0022] Step 1) The thermal ultrasonic modification treatment is performed at 55-65℃ for 50-70 minutes, followed by drying to obtain modified nano-alloy powder.

[0023] As a preferred option

[0024] After conversion, the mass ratio of CaO to MgO in the calcareous dolomite described in step 2) is (2-2.5):1, and the calcium and / or magnesium content in the calcareous dolomite accounts for 95 wt% or more of its total mass.

[0025] As a preferred option

[0026] The micronized powder in step 2) has a mesh size of 200-300.

[0027] Step 2) The oily plasticizer is dioctyl phthalate. The premixing process involves dispersing the micro powder in the oily plasticizer using ultrasonic-assisted dispersion, and preparing a dispersion with a solid content of 60-70 wt%, which is the compound slurry.

[0028] As a preferred option

[0029] Step 3) The lubricant is a microcrystalline wax with a molecular weight of 400-600;

[0030] In step 3), the mass ratio of PVC resin, lubricant, and modified nano-alloy powder is 100:(1.0-1.5):(1.5-2.5).

[0031] Step 3) The low-temperature dry mixing process is to stir and mix at 80-90℃ for 5-10 minutes.

[0032] As a preferred option

[0033] Step 3) The amount of the compound slurry used is 15-20g / 100g PVC resin;

[0034] Step 3) The stabilizer is a mixture of calcium-zinc stabilizer and organotin stabilizer. Both stabilizers used in this invention are purchased from Bangtai Chemical. The calcium-zinc stabilizer is a solid calcium-zinc stabilizer. Compared with liquid calcium-zinc stabilizer, solid calcium-zinc stabilizer is less prone to segregation and precipitation. Common PVC processing usually uses liquid calcium-zinc stabilizer (especially under the dosage conditions of this invention). However, due to the synergistic effect of multiple components and processes, this invention can effectively achieve the dispersion of solid calcium-zinc stabilizer, thereby effectively controlling costs and stabilizing the matrix more effectively. The dosage of calcium-zinc stabilizer is 1.8-2.2 g / 100 g PVC resin, and the dosage of organotin stabilizer is 0.3-0.7 g / 100 g PVC resin.

[0035] Step 3) The heating and premixing is carried out at 160-170℃ for 10-12 minutes.

[0036] As a preferred option

[0037] The crosslinking agent in step 3) is dicumyl peroxide, and its dosage is 1.5-2.5g / 100g PVC resin;

[0038] Step 3) The high-temperature mixing is carried out at 180-190℃ for 8-10 minutes.

[0039] As a preferred option

[0040] Step 4) The foaming agent is AC foaming agent, and its dosage is 0.5-1.0g / 100g PVC resin;

[0041] Step 4) The final mixing process is controlled at a temperature of 190-195℃ and a mixing time of 6-10 minutes. Then, a pressure of 20-35 MPa is applied at 40-60℃ and held for 2-5 minutes to press and form a pre-plate.

[0042] As a preferred option

[0043] Step 4) The gradient hot pressing process is performed on both sides of the pre-made sheet, and includes a pressurization stage, a depressurization stage, and a pressure holding stage in sequence.

[0044] The pressurization stage controls the hot pressing temperature to be 180–185°C, the hot pressing pressure to be 10–15 MPa, and the pressing time to be 60–120 s.

[0045] During the decompression phase, the temperature is controlled to drop to 150-155°C while the pressure is directly released, and the decompression phase is maintained for 30-60 seconds.

[0046] During the pressure holding stage, the temperature is controlled to drop to 40-60℃, the pressing pressure is 10-15MPa, and the pressing time is 3-5min. After the pressing is completed, the pressing is released and cooled to room temperature to obtain the stone-plastic composite flooring.

[0047] A type of stone-plastic composite flooring.

[0048] The core of the technical solution of this invention lies in filling with a relatively special alloy powder while initiating multiple chain reactions to achieve the dispersion of the alloy powder and the effective synergistic cooperation between the components, and to construct a specific microporous structure.

[0049] Specifically, this invention uses a special copper alloy, CSZ532, which was purchased from Anhui Dequan New Materials Co., Ltd., and is specifically a Cu alloy. 0.5 Sn 0.3 Zn 0.2 The ternary alloy (i.e., Cu:Sn:Zn atomic ratio of 5:3:2) has a lower melting point than other types of copper alloys. Moreover, its three components not only work synergistically but also have relatively high stability. The alloying elements Sn and Zn make it less likely for Cu in the alloy to oxidize excessively during the processing of this invention.

[0050] Based on the CSZ532 alloy, this invention utilizes a small amount of extremely low-melting-point segregated alloy phases in the alloy powder to form localized melting. These localized meltings create thermally activated points, such as some Sn-Zn eutectic alloy phases with melting points below 200°C. During the processing of this invention, these can act as dispersed thermally activated points, accelerating PVC chain segment movement and stimulating cross-linking reactions during high-temperature mixing and final mixing. Prior to this, during low-temperature dry mixing and heated premixing, Cu, the main component of the CSZ532 ternary alloy, as a transition metal, possesses a unique d-orbital electronic structure that effectively regulates electron density and promotes electron transfer. This electronic structure allows it to interact with the C-Cl bonds in PVC, reducing the dissociation energy of the C-Cl bonds and thus promoting homolytic cleavage to generate Cl· radicals. Furthermore, both Cu and Zn possess the ability to interact with Cl· radicals. -The ability to form coordination bonds enables multi-point coordination connections. This involves the formation of a preliminary synergistic initiation and construction of a dynamic physical cross-linking network through the self-components, and the formation of a CC or COC covalent cross-linking network through free radical recombination. This multi-network structure lays the foundation for the effective binding, dispersion, and subsequent fixation of CSZ, while also restricting PVC segment slippage during this stage.

[0051] In addition to the good performance of CSZ532 alloy powder in the PVC system and its ability to initially construct a dynamic physical cross-linking network, it also has a good promoting effect on the bonding between calcium-based stone powder filler and PVC. This is because, under the action of CSZ532 alloy powder, calcium-based stone powder can form more ion-dipole interactions with chloride ions formed by PVC chains, while copper and zinc in the dynamic physical cross-linking network can coordinate with hydroxyl groups (some mineral calcium carbonate surfaces are rich in hydroxyl groups) or carbonate ions on the surface of calcium carbonate, further indirectly enhancing the bonding between calcium-based stone powder and PVC. Compared to traditional calcium-based stone powder stone-plastic composite flooring that directly uses calcium carbonate, this invention uses lower-cost and more readily available high-calcium dolomite ore (i.e., calcareous dolomite). This is not only to reduce costs, but more importantly, during the research and development process, it was discovered that directly using calcium carbonate micropowder as a filler could lead to filler agglomeration, resulting in poor preparation effects. However, calcareous dolomite contains relatively abundant magnesium oxide, and even though its surface has more oxygen vacancies and alkaline sites, the zinc ions released by CSZ532 can form a Zn-O-Mg continuum with it. This allows the effective dispersion of CSZ532 alloy powder to effectively promote the dispersion of calcareous dolomite micropowder, inhibiting agglomeration while effectively controlling the dispersibility of both fillers without the need for additional operations to promote the dispersion of stone powder filler. This greatly simplifies the process and optimizes the preparation effect, and also produces further dynamic synergy, which significantly helps to improve the overall mechanical properties of stone-plastic composite flooring.

[0052] In addition, due to the addition and use of various fillers, in order to further ensure the dispersibility of the fillers, the present invention also adds a small amount of microcrystalline wax as a lubricant, which can work with the stabilizer to produce external lubrication synergy, effectively reducing the viscosity of materials during the refining process and promoting the dispersion of fillers. The better the uniformity of material dispersion, the more complete and uniform the multi-network it constructs, which can also effectively and significantly reduce the brittleness of stone-plastic composite flooring and give it better resistance to temperature changes.

[0053] After the three-stage refining in step 3), the present invention adds a foaming agent for final mixing and refining. This is to ensure that CSZ532 and calcareous dolomite can first form an effective uniform dispersion and relative fixation, and after local melting and thermal activation, the PVC chain segments move more. At this time, the foaming agent can form more fine and small bubbles. In this foaming process, the uniformly dispersed CSZ532 can also act as a nucleating agent. Especially after local melting and thermal activation, the surface roughness of CSZ532 alloy powder increases, which can effectively act as a nucleation point to promote bubble nucleation and drive the uniform dispersion of bubbles. The multiple network structure restricts the merging and escape of bubbles. Under the combined effect, the stone-plastic composite flooring forms rich and uniformly dispersed bubble pores. However, these bubble pores will inevitably appear on the surface of the stone-plastic composite flooring. Therefore, the present invention further performs gradient hot pressing treatment.

[0054] During the gradient hot pressing process, the first stage of high-temperature hot pressing (i.e., the pressurization stage) causes slight melting and damage to the surface. After a period of time, the temperature is immediately lowered and the pressure is released (i.e., the depressurization stage), which allows the surface bubbles to escape and simultaneously reactivates the local melting heat, resulting in a smooth and hard surface shell that seals the surface. This allows the front and back surfaces of the stone-plastic composite flooring to be effectively closed and fixed while increasing surface hardness, ensuring that the stone-plastic composite flooring has good heat and sound insulation performance. The final pressure holding stage further ensures the flatness of the stone-plastic composite flooring surface and performs the final optimization of the product surface.

[0055] In summary, this invention utilizes a special Cu-Sn-Zn ternary alloy as the core for multi-faceted synergy, constructing a multi-layered micro-network structure (including chemical cross-linking networks and dynamic physical cross-linking networks). This enhances the bonding strength between the special stone powder filler and the PVC matrix, promotes filler dispersion, and simultaneously acts as a nucleation point to promote bubble nucleation, comprehensively improving the various performance aspects of stone-plastic composite flooring. In contrast, this invention, during its development, also used a mixture of copper powder, zinc powder, and tin powder separately, instead of a ternary alloy. This resulted in suppressed self-synergistic capabilities and poor actual performance, especially in promoting dispersion and bubble nucleation, where the differences were significant. Therefore, the use of a ternary alloy is relatively more crucial.

[0056] In addition to the above-mentioned synergistic effects, the present invention also uses a combination of calcium-zinc stabilizer and organotin stabilizer. Due to the special nature of the system of the present invention, it is necessary to comprehensively optimize thermal stability, filler dispersibility and processability during the preparation process. Calcium-zinc stabilizer and organotin stabilizer can significantly improve the aforementioned performance aspects through complementary thermal stability, optimized filler dispersibility and synergistic processing performance, making the product quality more stable and the processing process more stable.

[0057] The beneficial effects of this invention are:

[0058] This invention utilizes fillers to stimulate multiple synergistic effects, constructs a multi-network structure, and improves the dispersion uniformity of the fillers. This comprehensively optimizes and enhances the mechanical properties, sound insulation, and heat insulation properties of calcium-based stone powder stone-plastic composite flooring, achieving a performance leap for low-cost products. Detailed Implementation

[0059] The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0060] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0061] Unless otherwise specified, the mass ratio of CaO to MgO in the calcareous dolomite used in the embodiments of the present invention is 2.2:1 after conversion, and the total content of calcium and magnesium in the calcareous dolomite is ≥95wt%.

[0062] Example 1

[0063] A method for preparing stone-plastic composite flooring, the method comprising:

[0064] 1) Place 300-mesh CSZ532 alloy powder in a 2wt% KH550-ethanol solution and perform thermal ultrasonic modification treatment at 60℃ for 60 min. After drying, the modified nano alloy powder is obtained.

[0065] 2) The calcium dolomite is crushed into 300-mesh powder, and then premixed with dioctyl phthalate to form a dispersion with a solid content of 65wt%, which is the compound slurry.

[0066] 3) Mix PVC resin, microcrystalline wax with a molecular weight of 500 and modified nano-alloy powder in a mass ratio of 100:1.25:2 and dry mix at 85℃ for 8 minutes. Then, add compound slurry at a dosage of 15g / 100g PVC resin, calcium-zinc stabilizer at a dosage of 2.0g / 100g PVC resin, and organotin stabilizer at a dosage of 0.5g / 100g PVC resin. Premix at 165℃ for 10 minutes. Then, add dicumyl peroxide at a dosage of 2.0g / 100g PVC resin and knead at 185℃ for 8 minutes to obtain the mixture.

[0067] 4) Add AC foaming agent to the mixture at a ratio of 0.8g / 100g PVC resin, and perform final mixing at 195℃ for 3 minutes. Then, apply 30MPa pressure at 55℃ for 5 minutes to press and form a pre-board. Process both sides of the pre-board in the following stages: pressurization, release, and holding. During the pressurization stage, control the hot pressing temperature at 185℃, the hot pressing pressure at 12MPa, and the pressing time at 120s. During the release stage, rapidly cool down to 155℃ and release the pressure directly. Hold the pressure for 45s. During the holding stage, control the temperature to drop to 50℃, the pressing pressure at 12MPa, and the pressing time at 5 minutes. After completion, release the pressure and cool to room temperature to obtain the stone-plastic composite flooring.

[0068] The performance of the stone-plastic composite flooring prepared in this example was characterized, including specific gravity characterization, surface porosity (both sides only), surface roughness Ra (both sides only), Taber abrasion test, surface hardness characterization (both sides only), impact strength characterization, sound insulation performance characterization, heat insulation performance characterization, and crack resistance characterization.

[0069] The Taber abrasion test load is 1.0 kg, and the unit is mg / 1000 rpm; the sound insulation performance characterization includes impact sound pressure reduction characterization (denoted as sound insulation A, specifically referring to international standard ISO 717-2) and airborne sound insulation (denoted as sound insulation B, specifically referring to international standard ISO 717-1); the thermal insulation performance characterization mainly refers to the thermal conductivity of the front and back sides of the stone-plastic composite flooring (unit is W / (m·K)); the crack resistance characterization is to conduct -10 / 40℃ cyclic heat preservation, each cycle is 12h, including a low temperature stage and a high temperature stage. In the low temperature stage, the sample is cooled to -10℃ and held for 6h before entering the high temperature stage, where the temperature is raised to 40℃ within 15min and held for 6h, and then the low temperature stage is entered again, where the temperature is cooled to -10℃ within 15min. After each high temperature stage, the sample is observed for cracking as the end point of the cycle, and the number of cycles in which cracking occurs is recorded. A maximum of 60 cycles are performed, and no cracking occurs after 60 cycles is marked as excellent.

[0070] The specific characterization results are shown in the table below.

[0071] <![CDATA[Specific gravity (g / cm 3 )]]> Surface porosity (%) Surface roughness Ra Taber wear Surface Shore Hardness D 1.69 3.7 1.9μm 7.2 86 <![CDATA[Impact strength (kJ / m 2 )]]> Sound insulation A (dB) Sound insulation (dB) thermal conductivity Crack resistance 11.3 21 37 0.049 excellent

[0072] The characterization results clearly show that the stone-plastic composite flooring of this invention exhibits a low specific gravity and a low surface porosity, while possessing a high actual internal porosity, resulting in excellent sound and heat insulation effects. From the perspectives of sound insulation A and sound insulation B, and thermal conductivity, the calcium carbonate stone-plastic composite flooring prepared by this invention significantly improves upon the shortcomings of traditional calcium-based stone powder stone-plastic composite flooring, which almost entirely lacks sound and heat insulation capabilities. Furthermore, the surface porosity and roughness indicate that the surface has been effectively treated, resulting in a smooth and flat surface. It also exhibits high rigidity, hardness, and strong wear resistance. On the other hand, stone-plastic composite flooring reinforced with metal fillers or silicon-based fillers generally suffers from mismatched coefficients of thermal expansion and poor crack resistance. However, the unique CSZ-Ca / Mg-bubble core system constructed in this invention creates a large number of voids inside, which not only provides sound and heat insulation but also allows for internal expansion. This significantly reduces freeze-thaw cycle cracking caused by differences in coefficients of thermal expansion, resulting in excellent performance in both northern and southern regions. This breaks through the original limitation that "calcium-based stone-plastic composite flooring is suitable for the north and silicon-based stone-plastic composite flooring is suitable for the south."

[0073] Example 2

[0074] A method for preparing stone-plastic composite flooring, the method comprising:

[0075] 1) Place 300-mesh CSZ532 alloy powder in a 2wt% KH550-ethanol solution and perform thermal ultrasonic modification treatment at 60℃ for 60 min. After drying, the modified nano alloy powder is obtained.

[0076] 2) The calcium dolomite is crushed into 300-mesh powder, and then premixed with dioctyl phthalate to form a dispersion with a solid content of 65wt%, which is the compound slurry.

[0077] 3) Mix PVC resin, microcrystalline wax with a molecular weight of 500 and modified nano-alloy powder at a mass ratio of 100:1.25:2.5 and dry mix at 85℃ for 8 minutes. Then, add compound slurry at a dosage of 20g / 100g PVC resin, calcium-zinc stabilizer at a dosage of 2.0g / 100g PVC resin, and organotin stabilizer at a dosage of 0.5g / 100g PVC resin. Premix at 165℃ for 10 minutes. Then, add dicumyl peroxide at a dosage of 2.0g / 100g PVC resin and mix at 185℃ for 8 minutes to obtain the mixture.

[0078] 4) Add AC foaming agent to the mixture at a ratio of 0.8g / 100g PVC resin, and perform final mixing at 195℃ for 3 minutes. Then, apply 30MPa pressure at 55℃ for 5 minutes to press and form a pre-board. Process both sides of the pre-board in the following stages: pressurization, release, and holding. During the pressurization stage, control the hot pressing temperature at 185℃, the hot pressing pressure at 12MPa, and the pressing time at 120s. During the release stage, rapidly cool down to 155℃ and release the pressure directly. Hold the pressure for 45s. During the holding stage, control the temperature to drop to 50℃, the pressing pressure at 12MPa, and the pressing time at 5 minutes. After completion, release the pressure and cool to room temperature to obtain the stone-plastic composite flooring.

[0079] The performance of the stone-plastic composite flooring prepared in this example was characterized, including specific gravity characterization, surface porosity (both sides only), surface roughness Ra (both sides only), Taber abrasion test, surface hardness characterization (both sides only), impact strength characterization, sound insulation performance characterization, thermal insulation performance characterization, and crack resistance characterization. The characterization methods were the same as in Example 1.

[0080] The specific characterization results are shown in the table below.

[0081] <![CDATA[Specific gravity (g / cm 3 )]]> Surface porosity (%) Surface roughness Ra Taber wear Surface Shore Hardness D 1.73 3.3 2.0μm 6.7 87 <![CDATA[Impact strength (kJ / m 2 )]]> Sound insulation A (dB) Sound insulation (dB) thermal conductivity Crack resistance 11.0 22 37 0.051 excellent

[0082] The above characterization results clearly show that increasing the relative proportion of filler in this example resulted in a significant increase in specific gravity and some changes in surface properties. Porosity decreased, roughness slightly increased, and abrasion decreased. The decrease in abrasion is particularly noteworthy. Firstly, the reduction was substantial. Secondly, while Taber abrasion loss in stone-plastic composite flooring is typically caused by poor filler bonding strength leading to detachment, the increased relative amount of filler in this invention actually increased abrasion. This indicates excellent bonding strength between the filler and the substrate, preventing surface filler from easily detaching and effectively strengthening the floor surface.

[0083] Example 3

[0084] A method for preparing stone-plastic composite flooring, the method comprising:

[0085] 1) Place 300-mesh CSZ532 alloy powder in a 2wt% KH550-ethanol solution and perform thermal ultrasonic modification treatment at 60℃ for 60 min. After drying, the modified nano alloy powder is obtained.

[0086] 2) The calcium dolomite is crushed into 300-mesh powder, and then premixed with dioctyl phthalate to form a dispersion with a solid content of 65wt%, which is the compound slurry.

[0087] 3) Mix PVC resin, microcrystalline wax with a molecular weight of 500 and modified nano-alloy powder at a mass ratio of 100:1.25:1.5 and dry mix at 85℃ for 8 minutes. Then add compound slurry at a dosage of 20g / 100g PVC resin, calcium-zinc stabilizer at a dosage of 2.0g / 100g PVC resin, and organotin stabilizer at a dosage of 0.5g / 100g PVC resin. Premix at 165℃ for 10 minutes. Then add dicumyl peroxide at a dosage of 2.0g / 100g PVC resin and knead at 185℃ for 8 minutes to obtain the mixture.

[0088] 4) Add AC foaming agent to the mixture at a ratio of 0.8g / 100g PVC resin, and perform final mixing at 195℃ for 3 minutes. Then, apply 30MPa pressure at 55℃ for 5 minutes to press and form a pre-board. Process both sides of the pre-board in the following stages: pressurization, release, and holding. During the pressurization stage, control the hot pressing temperature at 185℃, the hot pressing pressure at 12MPa, and the pressing time at 120s. During the release stage, rapidly cool down to 155℃ and release the pressure directly. Hold the pressure for 45s. During the holding stage, control the temperature to drop to 50℃, the pressing pressure at 12MPa, and the pressing time at 5 minutes. After completion, release the pressure and cool to room temperature to obtain the stone-plastic composite flooring.

[0089] The performance of the stone-plastic composite flooring prepared in this example was characterized, including specific gravity characterization, surface porosity (both sides only), surface roughness Ra (both sides only), Taber abrasion test, surface hardness characterization (both sides only), impact strength characterization, sound insulation performance characterization, thermal insulation performance characterization, and crack resistance characterization. The characterization methods were the same as in Example 1.

[0090] The specific characterization results are shown in the table below.

[0091] <![CDATA[Specific gravity (g / cm 3 )]]> Surface porosity (%) Surface roughness Ra Taber wear Surface Shore Hardness D 1.70 4.9 2.3μm 9.5 83 <![CDATA[Impact strength (kJ / m 2 )]]> Sound insulation A (dB) Sound insulation (dB) thermal conductivity Crack resistance 10.7 17 35 0.058 excellent

[0092] The characterization results clearly show that this example reduced the amount of CSZ532 alloy and increased the relative amount of calcareous dolomite, which led to an imbalance in the internal structure of the product. In terms of surface porosity, the relatively excessive amount of calcareous dolomite forming a bond with CSZ532 alloy may reduce the number of nucleation points used for bubble nucleation and fixation, resulting in increased bubble fusion and overflow. This directly manifests as an increased surface porosity. Furthermore, the relatively excessive amount of calcareous dolomite also prevents it from forming a highly uniform diffusion and bonding with CSZ532 alloy powder, resulting in increased surface roughness Ra and Taber wear, enhanced brittleness, and weakened overall sound and heat insulation effects. However, it remains relatively stable and still possesses good crack resistance, thus ensuring its stability in use. Overall, it still exhibits relatively superior performance.

[0093] Comparative Example 1

[0094] Three commercially available calcium-based stone powder stone-plastic composite flooring samples and two silicon-based stone powder stone-plastic composite flooring samples were subjected to the same performance characterization as in Example 1. The characterization results are shown in the table below.

[0095]

[0096] The table above clearly shows that both commercially available calcium-based stone powder stone-plastic composite flooring and silicon-based stone powder stone-plastic composite flooring exhibit distinct performance biases. For instance, calcium-based stone powder stone-plastic composite flooring generally has a higher Shore hardness, while silicon-based stone powder stone-plastic composite flooring has higher impact strength and superior sound and heat insulation compared to conventional calcium-based stone powder stone-plastic composite flooring. In terms of crack resistance, calcium-based stone powder stone-plastic composite flooring has a slight advantage. However, the characterization results of commercially available calcium-based stone powder (calcium carbonate) metal-reinforced (alumina-doped) stone-plastic composite flooring (C) also show that while the introduction of metal reinforcement improves hardness, wear resistance, impact strength, and heat insulation, it significantly reduces crack resistance, highlighting a significant deficiency in existing metal-reinforced calcium-based stone powder stone-plastic composite flooring solutions. In comparison, the special filler of this invention induces microstructure and enhances the structure, resulting in a decrease in the specific gravity of the calcium-based stone powder stone-plastic composite flooring, a significant improvement in wear resistance and impact strength, and thermal and sound insulation performance that is close to that of silicon-based stone powder stone-plastic composite flooring. Its crack resistance is far superior to all existing stone-plastic composite flooring. It is evident that the calcium-based stone powder stone-plastic composite flooring of this invention can achieve almost comprehensive improvement in the performance of stone-plastic composite flooring.

[0097] Comparative Example 2

[0098] A method for preparing stone-plastic composite flooring, the method comprising:

[0099] 1) Copper powder, tin powder and zinc powder of 300 mesh were placed in a 2wt% KH550-ethanol solution and subjected to thermal ultrasonic modification at 60℃ for 60 min. After drying, modified copper powder, modified tin powder and modified zinc powder were obtained respectively.

[0100] 2) The calcium dolomite is crushed into 300-mesh powder, and then premixed with dioctyl phthalate to form a dispersion with a solid content of 65wt%, which is the compound slurry.

[0101] 3) Mix PVC resin, microcrystalline wax with a molecular weight of 500, and metal powder (modified copper powder, modified tin powder, and modified zinc powder in a mass ratio of 2.43:2.72:1, approximately equivalent to an atomic ratio of 5:3:2) in a mass ratio of 100:1.25:2 and dry mix at 85°C for 8 minutes. Then, add compound slurry at a dosage of 15g / 100g PVC resin, calcium-zinc stabilizer at a dosage of 2.0g / 100g PVC resin, and organotin stabilizer at a dosage of 0.5g / 100g PVC resin. Premix at 165°C for 10 minutes. Then, add dicumyl peroxide at a dosage of 2.0g / 100g PVC resin and knead at 185°C for 8 minutes to obtain the mixture.

[0102] 4) Add AC foaming agent to the mixture at a ratio of 0.8g / 100g PVC resin, and perform final mixing at 195℃ for 3 minutes. Then, apply 30MPa pressure at 55℃ for 5 minutes to press and form a pre-board. Process both sides of the pre-board in the following stages: pressurization, release, and holding. During the pressurization stage, control the hot pressing temperature at 185℃, the hot pressing pressure at 12MPa, and the pressing time at 120s. During the release stage, rapidly cool down to 155℃ and release the pressure directly. Hold the pressure for 45s. During the holding stage, control the temperature to drop to 50℃, the pressing pressure at 12MPa, and the pressing time at 5 minutes. After completion, release the pressure and cool to room temperature to obtain the stone-plastic composite flooring.

[0103] The performance of the stone-plastic composite flooring prepared in this example was characterized, including specific gravity characterization, surface porosity (both sides only), surface roughness Ra (both sides only), Taber abrasion test, surface hardness characterization (both sides only), impact strength characterization, sound insulation performance characterization, thermal insulation performance characterization, and crack resistance characterization. The characterization methods were the same as in Example 1.

[0104] The specific characterization results are shown in the table below.

[0105] <![CDATA[Specific gravity (g / cm 3 )]]> Surface porosity (%) Surface roughness Ra Taber wear Surface Shore Hardness D 1.82 1.8 3.3μm 23.6 83 <![CDATA[Impact strength (kJ / m 2 )]]> Sound insulation A (dB) Sound insulation (dB) thermal conductivity Crack resistance 7.1 8 19 0.26 49

[0106] The characterization results above clearly show that replacing the original CSZ532 alloy powder with equivalent amounts of copper powder, tin powder, and zinc powder significantly weakens its synergistic effect, resulting in the inability to form CSZ532 cores. Instead, Cu cores and Zn cores are dispersed and formed. Tin powder, as an important alloying element, can hardly constitute an effective strengthening effect when used alone, and can only be mentioned as a filling effect. However, it is not suitable for filling strengthening. In terms of performance, due to the fragmentation of the core nodes, Cu and Zn cores are formed separately. This results in an inability to effectively disperse and coordinate the cores, leading to increased surface roughness and a sharp decline in wear resistance in the sample prepared in this example. Impact strength and sound insulation performance also cannot be effectively enhanced, making it closer to conventional calcium carbonate-based stone powder composite flooring, or even showing a reverse increase. This is mainly because the addition of metal fillers increases the thermal conductivity of the board. Especially when rich and uniform internal pores cannot be effectively constructed, metal fillers are more likely to form heat transfer chains, and the heat insulation effect is further reduced compared to conventional calcium carbonate-based stone powder composite flooring. Furthermore, due to the limited uniformity of dispersion of the various metal powder fillers, a multi-layer micro-network structure cannot be formed. The difference in thermal expansion coefficients between the fillers and the substrate also leads to a significant decrease in crack resistance.

[0107] Comparative Example 3

[0108] A method for preparing stone-plastic composite flooring, the method comprising:

[0109] 1) Place 300-mesh CSZ532 alloy powder in a 2wt% KH550-ethanol solution and perform thermal ultrasonic modification treatment at 60℃ for 60 min. After drying, the modified nano alloy powder is obtained.

[0110] 2) The calcium dolomite is crushed into 300-mesh powder, and then premixed with dioctyl phthalate to form a dispersion with a solid content of 65wt%, which is the compound slurry.

[0111] 3) Mix PVC resin, microcrystalline wax with a molecular weight of 500 and modified nano-alloy powder in a mass ratio of 100:1.25:2 and dry mix at 85℃ for 8 minutes. Then, add compound slurry at a dosage of 15g / 100g PVC resin, calcium-zinc stabilizer at a dosage of 2.0g / 100g PVC resin, and organotin stabilizer at a dosage of 0.5g / 100g PVC resin. Premix at 165℃ for 10 minutes. Then, add dicumyl peroxide at a dosage of 2.0g / 100g PVC resin and knead at 185℃ for 8 minutes to obtain the mixture.

[0112] 4) Add AC foaming agent to the mixture at a ratio of 0.8g / 100g PVC resin, and then perform final mixing at 195℃ for 3 minutes. After mixing, apply 30MPa pressure at 55℃ for 5 minutes and press to obtain stone-plastic composite flooring.

[0113] The performance of the stone-plastic composite flooring prepared in this example was characterized, including specific gravity characterization, surface porosity (both sides only), surface roughness Ra (both sides only), Taber abrasion test, surface hardness characterization (both sides only), impact strength characterization, sound insulation performance characterization, thermal insulation performance characterization, and crack resistance characterization. The characterization methods were the same as in Example 1.

[0114] The specific characterization results are shown in the table below.

[0115] <![CDATA[Specific gravity (g / cm 3 )]]> Surface porosity (%) Surface roughness Ra Taber wear Surface Shore Hardness D 1.69 9.6 2.6μm 11.2 81 <![CDATA[Impact strength (kJ / m 2 )]]> Sound insulation A (dB) Sound insulation (dB) thermal conductivity Crack resistance 11.8 11 23 0.098 excellent

[0116] The characterization results clearly show that without gradient hot pressing, the surface porosity of the stone-plastic composite flooring increases sharply, and its flatness decreases. Its overall wear resistance and hardness are inferior to the sample treated with gradient hot pressing, but its impact strength and crack resistance are retained, mainly due to its internal structure. On the other hand, the increased porosity also significantly reduces its sound and heat insulation capabilities, indicating that gradient hot pressing plays a crucial role in stabilizing and optimizing the performance of the board. However, it should be noted that if the temperature used in the first stage of hot pressing is too low, it will fail to activate localized surface heat, resulting in poor treatment effects. For example, if only a hot pressing temperature of 165℃ is used, with all other parameters remaining the same, the surface porosity will reach 8.2%, and its overall performance will be far inferior to the superior sample in Example 1.

[0117] Comparative Example 4

[0118] A method for preparing stone-plastic composite flooring, the method comprising:

[0119] 1) Place 300-mesh CSZ532 alloy powder in a 2wt% KH550-ethanol solution and perform thermal ultrasonic modification treatment at 60℃ for 60 min. After drying, the modified nano alloy powder is obtained.

[0120] 2) Premix 300-mesh calcium carbonate powder with dioctyl phthalate to form a dispersion with a solid content of 65 wt%, which is the compound slurry.

[0121] 3) Mix PVC resin, microcrystalline wax with a molecular weight of 500 and modified nano-alloy powder in a mass ratio of 100:1.25:2 and dry mix at 85℃ for 8 minutes. Then, add compound slurry at a dosage of 15g / 100g PVC resin, calcium-zinc stabilizer at a dosage of 2.0g / 100g PVC resin, and organotin stabilizer at a dosage of 0.5g / 100g PVC resin. Premix at 165℃ for 10 minutes. Then, add dicumyl peroxide at a dosage of 2.0g / 100g PVC resin and knead at 185℃ for 8 minutes to obtain the mixture.

[0122] 4) Add AC foaming agent to the mixture at a ratio of 0.8g / 100g PVC resin, and perform final mixing at 195℃ for 3 minutes. Then, apply 30MPa pressure at 55℃ for 5 minutes to press and form a pre-board. Process both sides of the pre-board in the following stages: pressurization, release, and holding. During the pressurization stage, control the hot pressing temperature at 185℃, the hot pressing pressure at 12MPa, and the pressing time at 120s. During the release stage, rapidly cool down to 155℃ and release the pressure directly. Hold the pressure for 45s. During the holding stage, control the temperature to drop to 50℃, the pressing pressure at 12MPa, and the pressing time at 5 minutes. After completion, release the pressure and cool to room temperature to obtain the stone-plastic composite flooring.

[0123] The performance of the stone-plastic composite flooring prepared in this example was characterized, including specific gravity characterization, surface porosity (both sides only), surface roughness Ra (both sides only), Taber abrasion test, surface hardness characterization (both sides only), impact strength characterization, sound insulation performance characterization, thermal insulation performance characterization, and crack resistance characterization. The characterization methods were the same as in Example 1.

[0124] The specific characterization results are shown in the table below.

[0125]

[0126]

[0127] The characterization results clearly show that replacing the calcareous dolomite powder in this invention with calcium carbonate in the preparation process resulted in a decrease in most properties, although the decrease was relatively controllable. However, a very significant decrease occurred in impact strength and crack resistance. This is mainly because calcium carbonate powder is more prone to agglomeration and localized stress concentration than calcareous dolomite powder, making it more susceptible to cracking and fracture under external impact or thermal shock conditions. Therefore, the preparation effect using calcareous dolomite is superior, and the cost is lower. Although an additional grinding process is required, the outsourcing cost of this process is low, and even if the processing is performed in-house, the difficulty and cost are relatively controllable, resulting in a higher overall cost-effectiveness.

Claims

1. A method for preparing stone-plastic composite flooring, characterized in that, The method includes: 1) The nano-alloy powder was placed in a pretreatment solution and subjected to thermal ultrasonic modification to obtain modified nano-alloy powder; 2) Crush the calcareous dolomite into micro powder, and then premix it with an oily plasticizer to form a compound slurry; 3) Mix PVC resin, lubricant and modified nano-alloy powder at low temperature, then add compound slurry and stabilizer for premixing at high temperature, and then add crosslinking agent for high temperature kneading to obtain the mixture. 4) Add foaming agent to the mixture and then press it into sheets to obtain pre-boards. Perform gradient hot pressing on the pre-boards to obtain stone-plastic composite flooring. Step 1) The nano-alloy powder is Cu 0.5 Sn 0.3 Zn 0.2 Alloy powder with a mesh size ≥ 300 mesh; Step 1) The pretreatment solution is a KH550-ethanol solution with a KH550 concentration of 1-3 wt%; Step 4) The gradient hot pressing process is performed on both sides of the pre-made sheet, and includes a pressurization stage, a depressurization stage, and a pressure holding stage in sequence. The pressurization stage controls the hot pressing temperature to be 180–185 °C, the hot pressing pressure to be 10–15 MPa, and the pressing time to be 60–120 s. During the decompression phase, the temperature is controlled to drop to 150–155 °C while the pressure is directly released, and the decompression phase is maintained for 30–60 seconds. During the pressure holding stage, the temperature is controlled to drop to 40-60 ℃, the pressing pressure is 10-15 MPa, and the pressing time is 3-5 min. After the pressing is completed, the pressing is released and cooled to room temperature to obtain the stone-plastic composite flooring.

2. The method for preparing a stone-plastic composite floor according to claim 1, characterized in that, Step 1) The thermal ultrasonic modification treatment is performed at 55-65 ℃ for 50-70 min, followed by drying to obtain modified nano-alloy powder.

3. The method for preparing a stone-plastic composite floor according to claim 1, characterized in that, Step 2) The mass ratio of CaO to MgO in the calcareous dolomite after conversion is (2-2.5):1, and the calcium and / or magnesium content in the calcareous dolomite accounts for 95 wt% or more of its total mass.

4. A method for preparing a stone-plastic composite floor according to claim 1 or 3, characterized in that, Step 2) The mesh size of the micro powder is 200-300 mesh; Step 2) The oily plasticizer is dioctyl phthalate. The premixing process involves dispersing the micro powder in the oily plasticizer using ultrasonic-assisted dispersion, and preparing a dispersion with a solid content of 60-70 wt%, which is the compound slurry.

5. The method for preparing a stone-plastic composite floor according to claim 1, characterized in that, Step 3) The lubricant is a microcrystalline wax with a molecular weight of 400-600; In step 3), the mass ratio of PVC resin, lubricant, and modified nano-alloy powder is 100:(1.0-1.5):(1.5-2.5). Step 3) The low-temperature dry mixing process is to stir and mix at 80-90 ℃ for 5-10 min.

6. The method for preparing a stone-plastic composite floor according to claim 1, characterized in that, Step 3) The amount of the compound slurry used is 15-20 g / 100 g PVC resin; Step 3) The stabilizer is a mixture of calcium-zinc stabilizer and organotin stabilizer, wherein the amount of calcium-zinc stabilizer is 1.8-2.2 g / 100 g PVC resin, and the amount of organotin stabilizer is 0.3-0.7 g / 100 g PVC resin; Step 3) The heating and premixing is carried out by stirring and premixing at 160-170 ℃ for 10-12 min.

7. The method for preparing a stone-plastic composite floor according to claim 1, characterized in that, Step 3) The crosslinking agent is dicumyl peroxide, and its dosage is 1.5-2.5 g / 100 g PVC resin; Step 3) The high-temperature mixing is carried out at 180-190 ℃ for 8-10 min.

8. The method for preparing a stone-plastic composite floor according to claim 1, characterized in that, Step 4) The foaming agent is AC foaming agent, and its dosage is 0.5-1.0 g / 100 g PVC resin; Step 4) The final mixing process is controlled at a temperature of 190-195 ℃ and a mixing time of 6-10 min. Then, a pressure of 20-35 MPa is applied at 40-60 ℃ and held for 2-5 min to press and form a pre-plate.

9. A stone-plastic composite flooring prepared by any one of claims 1 to 8.

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