High-wear-resistance and anti-aging softwood composite material for road paving and preparation method of softwood composite material

Abstract

The invention discloses a high-wear-resistance anti-aging softwood composite material for road paving and a preparation method thereof, and belongs to the technical field of road engineering materials. The preparation method comprises the following steps: firstly, carrying out surface activation treatment on cork particles by utilizing a silane coupling agent; preparing inorganic bonding liquid containing alkaline silica sol and gas-phase nano silicon dioxide, spraying the inorganic bonding liquid on the surface of the activated cork, wrapping micron-sized ceramic micro powder, and drying to form a hard inorganic mineralization layer; and S3, water-based aliphatic polyurethane containing a composite anti-aging additive is sprayed on the surface of the mineralized softwood, and an anti-aging sealing layer is formed through curing. The problems that natural softwood paving is poor in abrasion resistance and prone to aging and yellowing, and construction segregation is caused by low density are solved. The composite material has excellent wear resistance, ultraviolet aging resistance and high interface bonding strength, and is suitable for urban greenways, permeable pavements and elastic landscape pavement.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, specifically relating to a cork composite material with high wear resistance, anti-aging and anti-segregation properties, and its application in permeable pavement, elastic walkway and landscape paving. Background Technology

[0002] Cork has been increasingly used in paving materials for urban greenways, park trails, and children's playgrounds in recent years due to its excellent elasticity, sound absorption and shock absorption, heat insulation and environmental protection properties.

[0003] However, directly applying natural cork granules to outdoor road paving presents the following significant technical drawbacks: 1. Insufficient abrasion resistance and mechanical strength: Natural cork is relatively soft, and when directly mixed with adhesives, it is prone to wear and granule shedding under heavy traffic or light loads. 2. Poor weather resistance (yellowing and embrittlement): As described in existing technologies (CN202010837317.6 Manufacturing method of multi-coated film cork granules for road paving and KR101707780B1), cork contains lignin and polyphenols, which are easily photodegraded under ultraviolet radiation, leading to browning and fading. Furthermore, the polyurethane adhesives used in conjunction with cork are prone to yellowing, severely affecting aesthetics. 3. Water loss due to low bonding strength: The surface of natural cork is mainly composed of cork resin and wax, which are hydrophobic but difficult to form strong chemical bonds with commonly used polar polyurethane adhesives. Under rainwater immersion and freeze-thaw cycles, the interface is prone to debonding, resulting in a loose road surface. 4. Poor construction performance: Cork has an extremely low density, lower than that of polyurethane adhesive. It tends to float during construction mixing and paving, causing the adhesive to sink to the bottom, resulting in blockage of voids on the road surface (impermeability) or uneven surface strength.

[0004] Existing technologies (such as CN202010837317.6) attempt to solve this problem through multiple coatings, but in practice, simple organic coatings are prone to aging and peeling, and cannot fundamentally solve the problem of delamination during construction caused by the low density of cork. Summary of the Invention

[0005] This invention aims to solve the aforementioned technical problems and provide a cork composite material for road paving that is highly wear-resistant and anti-aging. This invention improves the hardness and wear resistance of the inorganic cork particles through surface mineralization modification and double-layer core-shell coating technology, while retaining their elasticity and significantly enhancing weather resistance and bonding strength.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a cork composite material for road paving with high wear resistance and anti-aging properties includes the following steps:

[0008] Step S1: Pretreatment of cork particles: Cork particles with a particle size of 3-5 mm are screened by air classifier. After washing and drying, they are immersed in silane coupling agent activation solution for treatment. The pH value is adjusted to 3.5-5.5 to promote silane hydrolysis. The mixture is stirred at 50-70℃. After stirring evenly, it is dried at 60-80℃ to obtain activated cork particles.

[0009] Furthermore, the silane coupling agent is KH-550 (γ-aminopropyltriethoxysilane).

[0010] Furthermore, the silane coupling agent activation solution is composed of the following components by weight percentage: silane coupling agent KH-550 (2%-4%), ethanol (70%-80%), and deionized water (balance).

[0011] Furthermore, the amount of silane coupling agent used is 1%-2% of the cork mass;

[0012] Step S2: Mix 90-95 parts of alkaline silica sol and 5-10 parts of fumed nano-silica in a high-speed shearing process to prepare an inorganic binder. Place the activated cork particles obtained in S1 in a mixer and preheat to 60-70°C. While stirring, spray 25%-40% of the above inorganic binder by weight of the cork onto the surface. Stir for 2-5 minutes. While continuing to stir, evenly sprinkle 20%-40% of the cork by weight of micron-sized ceramic powder onto the moist cork surface. Then dry at 80-110°C for 20-40 minutes to form a hard mineralized layer.

[0013] Furthermore, the silica sol has a solid content of 30%±1%, a pH value of 8.5-10, an average particle size of 10-20nm, and is of type JN-30.

[0014] Furthermore, the nano-silica is hydrophilic fumed silica with a specific surface area of ​​200±25 m². 2 / g. For example, Evonik Aerosil 200.

[0015] Furthermore, the micron-sized ceramic powder has a mesh size of 325-400 mesh and a Mohs hardness of ≥7; it is derived from waste ceramic grinding powder.

[0016] Furthermore, inorganic pigments, such as iron oxide red and chromium oxide green, may be added as needed, in amounts of 1 to 5 parts.

[0017] Furthermore, by adjusting the loading amount of mineralized slurry in S2, the bulk density of the modified cork particles was controlled at 0.35-0.55 g / cm³. 3 scope;

[0018] Step S3: Take an aqueous aliphatic polyurethane dispersion (solid content 35%-45%), add 1%-3% of a composite anti-aging additive (UV absorber and hindered amine light stabilizer, mass ratio 1:1) to the polyurethane to obtain an anti-aging liquid; spray the anti-aging liquid onto the surface of the cork particles obtained in step S2, stir thoroughly, and then cure at 80-90℃ to obtain a high wear-resistant and anti-aging cork composite material.

[0019] Furthermore, the aqueous aliphatic polyurethane dispersion is derived from Lacper® 4211 (Wanhua).

[0020] Furthermore, the mass ratio of the surface of the mineralized cork particles to the anti-aging liquid is 100:10-18.

[0021] Construction method: The prepared modified cork composite particles are mixed with one-component MDI polyurethane adhesive and then spread and cured. The mass ratio of the modified cork composite particles to the one-component moisture-curing polyurethane adhesive is 4:1 to 6:1.

[0022] This invention first utilizes a silane coupling agent to graft hydroxyl groups onto the cork surface, providing chemical bonding sites for the subsequent coating layer. Then, using a sol-gel method, a layer of nano-silica hard shell is grown in situ on the cork cell wall surface, and ceramic micropowder is introduced. This step not only significantly improves the surface hardness and wear resistance of the particles but also appropriately increases the specific gravity of the cork particles, preventing them from floating during construction. Finally, a polyurethane prepolymer is used to form the outer coating layer, sealing the internal structure, preventing moisture from entering the cork, and simultaneously shielding it from ultraviolet light to prevent photodegradation and discoloration of the cork itself.

[0023] The beneficial effects of this invention are:

[0024] This invention creates a wear-resistant layer on the cork surface through an inorganic mineralization layer, significantly reducing wear loss. The two-component anti-aging additives and the non-yellowing properties of polyurethane itself improve anti-aging and anti-yellowing performance. The modified cork particles have increased density, reducing the density difference with the adhesive and solving the problems of segregation during stirring and floating during installation.

[0025] The increased surface roughness (ceramic micro-powder protrusions) also significantly improves the tensile bond strength between cork particles and road surface adhesives. By controlling the amount of inorganic filler added, the particle density can be adjusted to a better application range, resulting in more uniform mixing with the adhesive, which is more conducive to construction and suitable for different application scenarios. Detailed Implementation

[0026] Example 1

[0027] (1) Select cork granules of Portuguese cork oak with a particle size of 3-5 mm. Prepare an ethanol-water solution containing 3% KH-550 silane coupling agent (1.5 kg KH-550, 38.5 kg ethanol, 10 kg water) as an activation solution. Spray 50 kg of the activation solution onto 100 kg of cork granules, adjust the pH value to 5.0, stir at 60 °C for 15 minutes, and dry at 80 °C to obtain pretreated cork granules.

[0028] (2) First, mix 25 kg of alkaline silica sol (JN-30) with 1.5 kg of fumed nano silica and disperse at high speed for 10 minutes to form 26.5 kg of inorganic binder liquid; then, put 100 kg of pretreated cork from step (1) into a mixer, preheat it to 60°C, add 26.5 kg of inorganic binder liquid, stir for 3 minutes to wet the surface of the cork, and while stirring continuously, evenly sprinkle 25 kg of micron-sized ceramic powder (325 mesh, about 25% of the cork mass) onto the wet cork surface, and then raise the temperature of the mixer to 95°C and stir at a constant temperature for 30 minutes to form a hard mineralized layer and obtain modified particles;

[0029] (3) Take 12 kg of waterborne aliphatic polyurethane prepolymer (Lacper® 4211 (Wanhua)), add 0.12 kg of UV absorber UV-329 and 0.12 kg of light stabilizer Tinuvin 292 to obtain anti-aging polyurethane adhesive. Mix the anti-aging polyurethane adhesive and the modified particles from step (2) at a mass ratio of 15:100 to make the coating cover the outside of the inorganic layer. Finally, cure at 80°C for 1 hour to obtain the final modified cork composite particles.

[0030] At the construction site, weigh 100 kg of the modified cork composite particles prepared above and add 20 kg of one-component moisture-curing polyurethane adhesive (MDI-based, Wanhua Chemical PM-200 modified product). That is, the mass ratio is 5:1. Mix for 3 minutes using a forced mixer, and then lay it on the roadbed manually or with a paver to a thickness of 15 mm.

[0031] Because the particles undergo mineralization and weight gain in step S2, they do not splash during mixing, do not float during paving, and have an extremely smooth surface after compaction. Complete curing occurs after 24 hours, forming a highly wear-resistant and permeable pavement.

[0032] Example 2

[0033] The difference between Example 2 and Example 1 is that the amount of ceramic micro powder used is different;

[0034] Step (1): Same as in Example 1.

[0035] Step (2): First, mix 33 kg of alkaline silica sol (JN-30) with 2 kg of fumed nano-silica and disperse at high speed for 10 minutes to prepare 35 kg of inorganic binder liquid. Place 100 kg of activated cork particles obtained in step (1) in a mixer, preheat to 60°C, and spray the above 35 kg inorganic binder liquid (about 35% of the cork mass) while stirring. Stir for 3 minutes to uniformly wet the cork surface. Under continuous stirring, evenly sprinkle 40 kg of micron-sized ceramic powder (325 mesh, about 40% of the cork mass) onto the wetted cork surface. At this time, the amount of powder is relatively large, and the ceramic powder is quickly captured and accumulated by the binder liquid layer. Then raise the temperature of the mixer to 95°C, and dry at a constant temperature for 30 minutes to form a thick and dense hard mineralized layer, thus obtaining modified particles.

[0036] Step (3): Same as in Example 1.

[0037] Example 3

[0038] The difference between Example 3 and Example 1 is that the amount of ceramic micro powder used is different;

[0039] Step (1): Same as in Example 1.

[0040] Step (2): First, mix 23.5 kg of alkaline silica sol (JN-30) with 1.5 kg of fumed nano-silica and disperse at high speed for 10 minutes to prepare 25 kg of inorganic binder liquid; Place 100 kg of activated cork particles obtained in step (1) in a mixer, preheat to 60°C, and spray the above 25 kg inorganic binder liquid (about 25% of the cork mass) while stirring, and stir for 3 minutes to uniformly wet the cork surface; Under continuous stirring, evenly sprinkle 20 kg of micron-sized ceramic powder (325 mesh, about 20% of the cork mass) onto the wetted cork surface. Then add it to the mixer and raise the temperature to 95°C, and dry at a constant temperature for 30 minutes to form a thin but uniform inorganic mineralization layer, thus obtaining modified particles.

[0041] Step (3): Same as in Example 1.

[0042] Comparative Example 1

[0043] The difference between Comparative Example 1 and Example 1 is that: pretreatment with KH-550 silane coupling agent was not used, step (1) was omitted, and cork was directly mixed with inorganic binder and ceramic powder. Other specific operations were the same as in Example 1.

[0044] The construction method is the same as in Example 1.

[0045] Comparative Example 2

[0046] Compared with Example 1, Comparative Example 2 differs in that: inorganic mineralization was not performed; step (2) was omitted, and the pretreated cork particles from step (1) were directly coated with anti-aging polyurethane in step (3). The specific operation was the same as in Example 1.

[0047] The construction method is the same as in Example 1.

[0048] Comparative Example 3

[0049] Compared with Example 1, Comparative Example 3 is different in that step (3) is omitted, aliphatic polyurethane resin is not sprayed, and the mineralized particles prepared in step (2) are directly used for paving.

[0050] The construction method is the same as in Example 1.

[0051] Comparative Example 4

[0052] The difference from Example 1 is that: in step S2, instead of using silica sol, an equal weight of ordinary polyurethane glue is used to mix ceramic micro powder to coat the cork.

[0053] Step (1) is the same as in Example 1.

[0054] Step (2) Take 26.5 kg of ordinary polyurethane adhesive and mix it with the pretreated cork particles from step (1). After stirring and wetting, add 25 kg of micron-sized ceramic powder. Cure at 80°C so that the ceramic powder is adhered to the cork surface by the organic adhesive.

[0055] Step (3): Same as in Example 1.

[0056] The construction method is the same as in Example 1.

[0057] Comparative Example 5

[0058] The difference in Example 1 is that in step S2, the micron-sized ceramic powder is replaced with glass microspheres.

[0059] Step (1): Same as in Example 1.

[0060] Step (2): The inorganic binder formulation is the same as in Example 1. The only difference is that 25 kg of ceramic powder is replaced with 25 kg of glass microspheres (with a particle size similar to 325 mesh ceramic powder). The rest of the process is the same as in Example 1.

[0061] Step (3): Same as in Example 1.

[0062] The examples and comparative examples were subjected to performance tests according to GB / T 14833-2011 "Synthetic Materials for Runway Surface Layers" and GB / T25993-2010 "Permeable Pavement Bricks and Permeable Pavement Panels":

[0063] Table 1:

[0064]

[0065] Comparing Examples 1-3, it can be seen that the density of the composite material can be controlled by adjusting the amount of ceramic micropowder, with Example 2 achieving a density of 0.52 g / cm³. 3 This is because a large amount of ceramic powder was used. During construction, this density is close to that of adhesive, making it suitable for walkways requiring a smooth surface. Example 3, however, has a density of 0.36 g / cm³. 3 Although lighter than Example 2, it retains more of the lightweight resilience of cork, making it more suitable for places with high elasticity requirements, such as children's playgrounds.

[0066] Comparative Example 1 lacks KH-550, and there are no chemical bonds between the inorganic shell and the cork. Therefore, its tensile bond strength is lower than that of Example 1, and it suffers from high wear resistance and shell detachment. Comparative Example 2 was not mineralized. It exhibits the worst wear resistance, indicating that the inorganic shell structure can reduce mechanical wear. Although Comparative Example 3 lacks polyurethane anti-aging coating for wear resistance, moisture easily penetrates the cork through the porous ceramic layer, resulting in high water absorption and severe discoloration during UV aging tests.

[0067] Comparative Example 4 used ordinary polyurethane to bond ceramic powder, with an abrasion value of 0.25 g and low tensile strength. Comparative Example 5 replaced the ceramic micropowder with smooth glass microspheres, resulting in a decrease in tensile bond strength. This confirms that the rough structure formed on the surface by micron-sized ceramic powder is beneficial to improving tensile bond strength.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high wear-resistant and anti-aging cork composite material for road paving, characterized in that, Includes the following steps: (1) After cleaning and drying the cork particles, surface treatment was performed with silane coupling agent activation solution, and then dried to obtain activated cork particles; (2) An inorganic binder was prepared by mixing alkaline silica sol with fumed nano-silica; After the activated cork particles are mixed and moistened with an inorganic binder, micron-sized ceramic powder is added for coating, and then dried and cured to form a hard mineralized layer on the cork surface. (3) Spray an aqueous aliphatic polyurethane dispersion containing composite anti-aging additives onto the surface of the particles obtained in step (2), and after curing, a high wear-resistant and anti-aging cork composite material is obtained.

2. The preparation method of the high wear-resistant and anti-aging cork composite material for road paving according to claim 1, characterized in that, In step (1), the silane coupling agent is γ-aminopropyltriethoxysilane (KH-550); the silane coupling agent activation solution is composed of silane coupling agent, ethanol and deionized water, wherein the amount of silane coupling agent is 1%-2% of the weight of cork.

3. The preparation method of the high wear-resistant and anti-aging cork composite material for road paving according to claim 1, characterized in that, In step (2), the inorganic adhesive is made by high-speed shearing mixing of 90-95 parts by weight of alkaline silica sol and 5-10 parts by weight of fumed nano silica; the amount of the inorganic adhesive is 25%-40% of the weight of the cork.

4. The preparation method of the high wear-resistant and anti-aging cork composite material for road paving according to claim 3, characterized in that, The alkaline silica sol has an average particle size of 10-20 nm and a solid content of 30%±1%; the fumed nano silica is hydrophilic and has a specific surface area of ​​200±25 m² / g.

5. The method for preparing the high wear-resistant and anti-aging cork composite material for road paving according to claim 1, characterized in that, In step (2), the micron-sized ceramic powder has a mesh size of 325-400 mesh, a Mohs hardness of ≥7, and is added at 20%-40% of the cork mass.

6. The method for preparing the high wear-resistant and anti-aging cork composite material for road paving according to claim 1, characterized in that, In step (2) and step (3), the composite anti-aging additive is composed of ultraviolet absorber and hindered amine light stabilizer in a mass ratio of 1:1, and the amount added is 1%-3% of the mass of waterborne aliphatic polyurethane.

7. The method for preparing the high wear-resistant and anti-aging cork composite material for road paving according to claim 1, characterized in that, The prepared cork composite material has a bulk density of 0.35-0.55 g / cm³. 3 scope.

8. A cork composite material for road paving with high wear resistance and anti-aging properties prepared by the method according to any one of claims 1-7.

9. The application of the high wear-resistant and anti-aging cork composite material for road paving according to claim 8 in permeable pavements, elastic walkways, and landscape paving, characterized in that, During construction, the cork composite material is mixed with a single-component moisture-curing polyurethane adhesive at a mass ratio of 4:1 to 6:1 and then spread.

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