Composite stone crystal floor with solid wood veneer parquet process surface and production process

Abstract

The invention relates to the field of wood processing and novel building materials, in particular to a composite stone crystal floor with a solid wood veneer parquet process surface and a production process. Comprising the following steps: carrying out variable-pressure impregnation on a solid wood veneer by using an impregnation liquid containing isocyanate, silicone oil and epoxy resin, and drying to obtain a modified layer; the random copolymer polypropylene is grafted with maleic anhydride and then reacts with diamine to prepare an imide modified amphiphilic hot melt adhesive; the modified layer and the stone crystal base material are subjected to hot-pressing compounding through a hot melt adhesive, and the composite stone crystal floor is obtained through cold pressing and curing. According to the invention, the problem that the solid wood thin skin absorbs water and expands in a humid or high-temperature environment is effectively solved, the thickness expansion rate after boiling in boiling water is greatly reduced, and the floor is endowed with excellent dimensional stability.

Description

Technical Field

[0001] This invention relates to the field of wood processing and new building materials, specifically to a composite stone crystal floor with a surface of solid wood veneer mosaic and its production process. Background Technology

[0002] Existing composite stone-crystal flooring with a solid wood veneer parquet finish faces the main technical challenges of poor interfacial bonding stability and insufficient dimensional stability of the solid wood layer. Solid wood veneers naturally contain a large number of polar hydroxyl groups, exhibiting strong hydrophilicity. In humid or high-temperature environments, they easily absorb water, leading to dramatic volume expansion. In contrast, the stone-crystal substrate is relatively dimensionally stable. This difference in the rate of expansion between these dissimilar materials generates significant shear stress at the interface. Simultaneously, traditional commercially available polyurethane (PUR) hot melt adhesives rely primarily on chemical cross-linking, resulting in a brittle adhesive layer lacking effective stress dissipation mechanisms and dynamic bonding networks. Under extreme conditions such as humid heat cycling or boiling water treatment, the adhesive layer cannot adapt to and buffer the aforementioned shear stress, easily leading to brittle fracture or hydrolysis. This results in a significant decrease in the flooring's resistance to humid heat peeling, excessive thickness expansion, and consequently, delamination, cracking, and other destructive phenomena, making it difficult to meet the requirements for long-term stable use. Summary of the Invention

[0003] The purpose of this invention is to provide a composite stone-crystal flooring with a solid wood veneer mosaic surface and its manufacturing process, which solves the delamination defects caused by water absorption and expansion of solid wood veneer in humid and hot environments and by interfacial stress concentration. Furthermore, it significantly improves the dimensional stability and resistance to humid and hot peeling by constructing an interface with a dynamic stress dissipation mechanism. Specifically, the technical solution of this invention includes the following steps: The solid wood parquet veneer is placed in a pressure tank and injected with a lignin-affinity hydrophobic stabilizing impregnation solution. After pressure-switching impregnation and gradient temperature drying, a modified solid wood layer is obtained. An imide-modified amphiphilic hot melt adhesive is made into an adhesive film through a casting machine and laid between the stone crystal substrate and the modified solid wood layer. The film is then sent into a hot press and hot-pressed under the action of an isobaric buffer pad. After cold pressing and static curing, a composite stone crystal floor is obtained. The preparation of the lignin-affinity hydrophobic stabilizing impregnation solution includes the following steps: Isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil and catalyst were mixed and refluxed at a constant temperature under nitrogen protection. After cooling, 3,5-dimethylpyrazole was added and stirred. Epoxy-modified acrylic resin solution was added and ultrasonically dispersed to obtain the impregnation solution. The preparation of imide-modified amphiphilic hot melt adhesive includes the following steps: Random copolymer polypropylene, maleic anhydride and initiator are melt-grafted to obtain an intermediate; the intermediate is dissolved in decahydronaphthalene, isophorone diamine is added dropwise, and the product after reflux reaction is added to a tackifying resin and an antioxidant, and reactive extrusion is carried out. After removing the solvent by multi-stage vacuum distillation or high vacuum flash evaporation, granulation is performed to obtain a hot melt adhesive.

[0004] Preferably, the mass fractions of isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, catalyst, 3,5-dimethylpyrazole, and epoxy-modified acrylic resin solution are (25-35):(40-60):(5-15):(0.03-0.08):(5.0-6.0):(8-12).

[0005] Preferably, the mass ratio of random copolymer polypropylene, maleic anhydride, and initiator is 100:(6-10):(0.1-0.3); in the preparation of the imide-modified amphiphilic hot melt adhesive, the mass ratio of the intermediate, decahydronaphthalene, isophorone diamine, tackifying resin, and antioxidant is 50:(180-220):(1.0-5.0):(15-25):(0.3-0.8).

[0006] Preferably, the process conditions for pressure-variable impregnation are: vacuum degree -0.07MPa to -0.09MPa, maintained for 10-20 minutes; pressurized to 0.6-1.0MPa, and cycled 2-4 times.

[0007] The preferred process conditions for gradient temperature drying are: first drying at 40-50℃ for 1.5-2.5 hours, and then drying at 75-85℃ for 0.5-1.5 hours.

[0008] Preferably, the hot-pressing composite process conditions are: hot-pressing temperature 140-155℃, pressure 3.5-4.5MPa, and holding time 60-120 seconds.

[0009] Preferably, in the process of preparing the lignin-affinity hydrophobic stabilized impregnation solution, the constant temperature reflux reaction temperature is 75-85℃ and the time is 2-4 hours; the temperature of the stirring reaction after adding 3,5-dimethylpyrazole is 35-45℃.

[0010] Preferably, in the process of preparing imide-modified amphiphilic hot melt adhesive, the melting grafting temperature is 155-165℃; the reflux reaction is maintained at a slight boiling state for 1.5-2.5 hours; the vacuum devolatilization temperature is 175-255℃, and the pressure is -0.08MPa to -0.095MPa.

[0011] A composite stone crystal floor with a solid wood veneer inlay process is prepared using the aforementioned manufacturing process for a composite stone crystal floor.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses a pressure-switching impregnation process to inject a lignin-affinity hydrophobic stabilizing impregnating solution into the interior of solid wood parquet veneer. The active groups in the impregnating solution can chemically react with the hydrophilic hydroxyl groups in wood cellulose and lignin, sealing the main water absorption sites. At the same time, the terminal hydroxyl-modified silicone oil segments form a hydrophobic shielding network at the microscopic level. This synergistic effect of chemical sealing and physical shielding significantly reduces the surface energy and water absorption of the solid wood layer, effectively solving the problem of water absorption and swelling of solid wood veneer in humid or high-temperature environments, greatly reducing the thickness expansion rate after boiling in water, and giving the flooring excellent dimensional stability. 2. The imide-modified amphiphilic hot melt adhesive prepared in this invention has a unique molecular structure. Rigid cyclic structures and polar groups are introduced through grafting reactions, constructing a dense dynamic hydrogen bond network between molecular chains. Under hygrothermal stress, the hydrogen bond network preferentially dissociates as sacrificial units to dissipate energy, and after stress release, it reforms into physical crosslinks through molecular chain creep, effectively avoiding the brittle fracture caused by stress concentration in traditional chemically crosslinked adhesive layers. At the same time, the amphiphilic structure of this hot melt adhesive achieves excellent compatibility and wetting with hydrophilic wood and stone crystal substrates, respectively, significantly improving the flooring's resistance to hygrothermal peel strength. 3. This invention achieves long-term stable bonding of heterogeneous interfaces through the combination of modified solid wood layers and special hot melt adhesives. The low hygroscopicity of the modified solid wood layers reduces volume expansion caused by humidity changes from the source, lowering shear stress at the interface. Meanwhile, the imide-modified amphiphilic hot melt adhesive provides a rigid-flexible bonding layer, which supports the interface with a rigid structure and buffers residual stress with a dynamic bonding mechanism. The synergistic effect of the two creates a dual protection system that is externally water-repellent and internally crack-resistant, effectively solving the technical problem of composite stone crystal flooring being prone to delamination and cracking under extreme humid and hot cycling conditions. 4. This invention employs a gradient temperature drying and isobaric buffer hot-pressing composite process. Gradient drying, by controlling the temperature in stages, avoids stress cracking of the wood caused by rapid moisture evaporation, ensuring the flatness of the modified solid wood layer. In the hot-pressing composite stage, the use of isobaric buffer pads in conjunction with specific process parameters ensures that the hot melt adhesive flows and wets the uneven mosaic texture, eliminating air bubbles and defects inside the adhesive layer, further improving the yield and appearance quality of the composite flooring. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a flowchart illustrating the production process of a composite stone crystal floor with a solid wood veneer mosaic surface, according to the present invention. Figure 2 SEM microstructure of the modified solid wood layer in its cell cavity-filled state. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example

[0015] This embodiment provides a manufacturing process for composite stone-crystal flooring with a solid wood veneer mosaic surface, specifically improving the bonding stability of the interface between the solid wood and the stone-crystal substrate. The manufacturing process is as follows: Figure 1 As shown, the production process includes the following steps: A 0.6mm thick solid wood parquet veneer is placed in a pressure tank, and a lignin-affinity hydrophobic stabilizing impregnation solution is injected. The pressure tank is evacuated to -0.07MPa and maintained for 20 minutes. The pressure is then increased to 0.6MPa, and four pressure-relief cycles are performed for pressure-variable impregnation. After removal, the veneer is first dried at 40℃ for 2.5 hours, and then dried at 75℃ for 1.5 hours to obtain a modified solid wood layer. An imide-modified amphiphilic hot melt adhesive is then cast to a thickness of 0mm using a casting machine. A 0.5mm thick adhesive film is laid between the stone-crystalline substrate and the modified solid wood layer, and then fed into a hot press. Under the action of an isobaric buffer pad, the hot pressing temperature is set to 140℃, the pressure to 1.0MPa, and the holding time to 120 seconds for hot pressing and bonding. After cold pressing equilibration and curing at 25℃ for 24 hours, the composite stone-crystalline flooring is obtained. Under these process conditions, the lignin-affinity hydrophobic stabilizing impregnation solution effectively penetrates into the wood cell cavities and cell walls. The SEM microstructure of the modified solid wood layer in the cell cavity-filled state is shown in the image. Figure 2 As shown, the wood dimensions were locked by unsealing during subsequent hot pressing; simultaneously, the imide-modified amphiphilic hot melt adhesive completed initial wetting at a lower hot pressing temperature, and the flooring exhibited basic resistance to damp heat, with a damp heat peel strength of 3.8 N / mm and a thickness expansion rate of 2.5% after boiling in water for 4 hours. The preparation of the lignin-affinity hydrophobic stabilized impregnation solution includes the following steps: isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, and dibutyltin dilaurate catalyst are mixed and refluxed at 75°C for 4 hours under nitrogen protection. The mixture is then cooled to 35°C, 3,5-dimethylpyrazole is added, and the mixture is stirred for 3 hours. Finally, an epoxy-modified acrylic resin solution is added, and the mixture is ultrasonically dispersed for 30 minutes to obtain the lignin-affinity hydrophobic stabilized impregnation solution. The mass ratio of isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, catalyst, 3,5-dimethylpyrazole, and epoxy-modified acrylic resin solution is 25:40:5:0.03:5.0:8. The preparation of the imide-modified amphiphilic hot melt adhesive includes the following steps: random copolymer polypropylene, maleic anhydride, and DCP initiator are melt-grafted at 155°C to obtain an intermediate; the intermediate is dissolved in decahydronaphthalene, isophorone diamine is added dropwise, and the mixture is refluxed to obtain a prepolymer solution containing an amide acid structure; this prepolymer solution is pumped into a twin-screw extruder equipped with a multi-stage devolatilization module, and reactive extrusion is performed in the molten state at 190-210°C. By controlling the shear and residence time of the screw, the prepolymer undergoes thermal cyclization and dehydration, completely converting the anhydride groups into heat-resistant imide structures, while strictly controlling the dihydronaphthalene structure. The molar ratio of amine to grafted anhydride is adjusted to avoid excessive chemical cross-linking between molecules leading to gelation. Premixed hydrogenated petroleum resin and antioxidant are added to the feed port at the rear end of the extruder for online melt blending. Finally, the decahydronaphthalene solvent and small molecule byproducts generated in the reaction are deeply removed through a multi-stage high-vacuum flash evaporation and degassing section. The resulting product is directly extruded and granulated to obtain an imide-modified amphiphilic hot melt adhesive. The mass ratio of random copolymer polypropylene, maleic anhydride, and initiator is 100:6:0.1; the mass ratio of intermediate, decahydronaphthalene, isophorone diamine, tackifying resin, and antioxidant is 50:180:1.0:15:0.3. Example

[0016] This embodiment provides a production process for composite stone-crystal flooring with a solid wood veneer parquet finish. Through the synergistic effect of the components, a stress dissipation mechanism is constructed at the interface. The production process includes the following steps: placing a 0.8mm thick solid wood parquet veneer in a pressure tank, injecting a lignin-affinity hydrophobic stabilizing impregnation solution, evacuating the pressure tank to -0.08MPa and maintaining it for 15 minutes, then pressurizing to 0.8MPa, performing three pressure-relief cycles of pressure variation impregnation, removing the veneer and drying it first at 45℃ for 2 hours, then at 80℃ for 1 hour to obtain a modified solid wood layer; and then forming a 0.08mm thick film of imide-modified amphiphilic hot melt adhesive using a casting machine. The adhesive film is laid between the stone-crystal substrate and the modified solid wood layer, and then fed into a hot press. Under the action of an isobaric buffer pad, the hot pressing temperature is set at 148℃, the pressure at 1.2MPa, and the holding time at 90 seconds for hot pressing and bonding. After cold pressing equilibration and curing at 25℃ for 48 hours, the composite stone-crystal flooring is obtained. Under these parameters, the density of hydrophobic groups in the lignin-affinity hydrophobic stabilizing impregnation solution is moderate, effectively blocking moisture without generating excessive steric hindrance. The intermolecular hydrogen bonding and grafting rate of the imide-modified amphiphilic hot melt adhesive reach the optimal balance, giving the interface excellent toughness and strength. The wet heat peel strength reaches 4.8N / mm, and the thickness expansion rate after boiling in water for 4 hours is only 2.9%. The preparation of the lignin-affinity hydrophobic stabilized impregnation solution includes the following steps: isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, and dibutyltin dilaurate catalyst are mixed and refluxed at 80°C for 3 hours under nitrogen protection. The mixture is then cooled to 40°C, 3,5-dimethylpyrazole is added, and the mixture is stirred for 2.5 hours. Finally, an epoxy-modified acrylic resin solution is added, and the mixture is ultrasonically dispersed for 30 minutes to obtain the lignin-affinity hydrophobic stabilized impregnation solution. The mass ratio of isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, catalyst, 3,5-dimethylpyrazole, and epoxy-modified acrylic resin solution is 30:50:10:0.05:5.5:10. The preparation of the imide-modified amphiphilic hot melt adhesive includes the following steps: random copolymer polypropylene, maleic anhydride, and DCP initiator are melt-grafted at 160°C to obtain an intermediate; the intermediate is dissolved in decahydronaphthalene, isophorone diamine is added dropwise, and the mixture is refluxed to obtain a prepolymer solution containing an amide acid structure; the prepolymer solution is pumped into a twin-screw extruder equipped with a multi-stage devolatilization module, and reactive extrusion is performed in the molten state at 195-215°C. By controlling the shear and residence time of the screw, the anhydride groups are converted in situ into heat-resistant imides. The ring structure involves adding hydrogenated petroleum resin as a tackifying resin and antioxidant at the feed port of the extruder's rear section for online melt blending. Finally, the decahydronaphthalene solvent and small molecule byproducts generated during the reaction are deeply removed through a multi-stage high-vacuum flash evaporation and degassing section. The resulting product is then directly extruded and granulated to obtain an imide-modified amphiphilic hot melt adhesive. The mass ratio of random copolymer polypropylene, maleic anhydride, and initiator is 100:8:0.2; the mass ratio of intermediate, decahydronaphthalene, isophorone diamine, tackifying resin, and antioxidant is 50:200:3.0:20:0.5. Example

[0017] This embodiment provides a production process for composite stone-crystal flooring with a solid wood veneer parquet finish, aiming to investigate the performance under high hydrophobic component content and high crosslinking density. The production process includes the following steps: placing a 1.2mm thick solid wood parquet veneer in a pressure tank, injecting a lignin-affinity hydrophobic stabilizing impregnation solution, evacuating the pressure tank to -0.09MPa and maintaining it for 10 minutes, then pressurizing to 1.0MPa, performing two pressure-relief cycles of pressure variation impregnation, removing the veneer and drying it first at 50℃ for 1.5 hours, then at 85℃ for 0.5 hours to obtain a modified solid wood layer; and then applying an imide-modified amphiphilic hot melt adhesive. A 0.10mm thick adhesive film was produced by a casting machine and laid between the stone-crystal substrate and the modified solid wood layer. The film was then fed into a hot press, and under the action of an isobaric buffer pad, the hot pressing temperature was set to 150℃, the pressure to 1.2MPa, and the holding time to 90 seconds for hot pressing and bonding. After cold pressing equilibration and curing at 30℃ for 72 hours, the composite stone-crystal flooring was obtained. In this embodiment, although the high content of hydrophobic components gave the wood excellent dimensional stability and the thickness expansion rate decreased to 2.6% after boiling in water for 4 hours, the high crosslinking density increased the modulus of the adhesive layer, and the wet heat peel strength was 3.5N / mm, which still met the usage requirements. The preparation of the lignin-affinity hydrophobic stabilized impregnation solution includes the following steps: isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, and dibutyltin dilaurate catalyst are mixed and refluxed at 85°C for 2 hours under nitrogen protection. The mixture is then cooled to 45°C, 3,5-dimethylpyrazole is added, and the mixture is stirred for 2 hours. Finally, an epoxy-modified acrylic resin solution is added, and the mixture is ultrasonically dispersed for 40 minutes to obtain the lignin-affinity hydrophobic stabilized impregnation solution. The mass ratio of isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, catalyst, 3,5-dimethylpyrazole, and epoxy-modified acrylic resin solution is 35:60:15:0.08:6.0:12. The preparation of the imide-modified amphiphilic hot melt adhesive includes the following steps: random copolymer polypropylene, maleic anhydride, and DCP initiator are melt-grafted at 165°C to obtain an intermediate; the intermediate is dissolved in decahydronaphthalene, isophorone diamine is added dropwise, and the mixture is refluxed to obtain a prepolymer solution containing an amide acid structure; the prepolymer solution is pumped into a twin-screw extruder equipped with a multi-stage devouring module, and reactive extrusion is performed in the molten state at 200-220°C. By controlling the shear and residence time of the screw, the anhydride groups are converted in situ into imide rings. The process involves adding hydrogenated petroleum resin as a tackifying resin and antioxidant at the feed port of the extruder's rear section for online melt blending. Finally, the decahydronaphthalene solvent and small molecule byproducts generated during the reaction are thoroughly removed through a multi-stage high-vacuum flash evaporation and degassing section. The resulting product is then directly extruded and granulated to obtain an imide-modified amphiphilic hot melt adhesive. The mass ratio of random copolymer polypropylene, maleic anhydride, and initiator is 100:10:0.3; the mass ratio of intermediate, decahydronaphthalene, isophorone diamine, tackifying resin, and antioxidant is 50:220:5.0:25:0.8. Example

[0018] This embodiment provides a production process for composite stone-crystal flooring with a solid wood veneer parquet finish. The process uses a low hydrophobic component ratio and a suitable crosslinking agent ratio. The production process includes the following steps: placing the solid wood parquet veneer in a pressure tank, injecting a lignin-affinity hydrophobic stabilizing impregnation solution, evacuating the pressure tank to -0.075 MPa and maintaining this vacuum for 18 minutes, then pressurizing to 0.7 MPa and performing three pressure-relief cycles of pressure variation impregnation. After removal, the flooring is first dried at 42°C for 2 hours, then dried at 78°C for 1.2 hours to obtain a modified solid wood layer; imide-modified amphiphilic hot melt adhesive is then applied via a casting mechanism. A glue film is formed and laid between the stone crystal substrate and the modified solid wood layer. It is then fed into a hot press. Under the action of an isobaric buffer pad, the hot pressing temperature is set to 145℃, the pressure to 1.3MPa, and the holding time to 100 seconds for hot pressing and bonding. After cold pressing and static curing, the composite stone crystal flooring is obtained. Under these conditions, the coverage of the lignin-affinity hydrophobic stabilizing impregnation liquid on the wood is slightly low, resulting in a slight increase in the water absorption and swelling rate to 3.5%. However, due to the good flexibility of the imide-modified amphiphilic hot melt adhesive, the interface can adapt to slight deformation, and the wet heat peel strength remains at 4.1N / mm, with stable overall performance. The preparation of the lignin-affinity hydrophobic stabilized impregnation solution includes the following steps: isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, and catalyst are mixed and refluxed at 78°C for 3.5 hours under nitrogen protection. The mixture is then cooled to 38°C, 3,5-dimethylpyrazole is added, and the mixture is stirred for 2.8 hours. Finally, an epoxy-modified acrylic resin solution is added and ultrasonically dispersed to obtain the lignin-affinity hydrophobic stabilized impregnation solution. The mass ratio of isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, catalyst, 3,5-dimethylpyrazole, and epoxy-modified acrylic resin solution is 28:45:7:0.04:5.2:9. The preparation of imide-modified amphiphilic hot melt adhesive includes the following steps: random copolymer polypropylene, maleic anhydride, and initiator are melt-grafted at 158°C to obtain an intermediate; the intermediate is dissolved in decahydronaphthalene, isophorone diamine is added dropwise, and the mixture is refluxed to obtain a prepolymer solution containing an amide acid structure; the prepolymer solution is pumped into a twin-screw extruder equipped with a multi-stage devolatilization module, and reactive extrusion is performed in the molten state at 190-210°C; by controlling the shear and residence time of the screw, the anhydride groups are converted in situ to imides. The ring structure involves adding tackifying resin and antioxidant to the feed port at the rear of the extruder for online melt blending. Finally, the solvent and small molecule byproducts generated in the reaction are deeply removed through a multi-stage high-vacuum flash evaporation and degassing section. The resulting product is then directly extruded and granulated to obtain an imide-modified amphiphilic hot melt adhesive. The mass ratio of random copolymer polypropylene, maleic anhydride, and initiator is 100:7:0.15; the mass ratio of intermediate, decahydronaphthalene, isophorone diamine, tackifying resin, and antioxidant is 50:190:2.0:18:0.4. Example

[0019] This embodiment provides a production process for composite stone-crystal flooring with a solid wood veneer parquet finish. The process utilizes a relatively high ratio of hydrophobic components and crosslinking agents. The production process includes the following steps: placing the solid wood parquet veneer in a pressure tank, injecting a lignin-affinity hydrophobic stabilizing impregnation solution, evacuating the pressure tank to -0.085 MPa and maintaining this pressure for 12 minutes, then pressurizing to 0.9 MPa and performing three pressure-relief cycles of pressure variation impregnation. After removal, the flooring is first dried at 48°C for 1.8 hours, then dried at 82°C for 0.8 hours to obtain a modified solid wood layer. An imide-modified amphiphilic hot melt adhesive is then applied through a casting machine. A film is prepared and laid between the stone-crystal substrate and the modified solid wood layer. The film is then fed into a hot press. Under the action of an isobaric buffer pad, the hot pressing temperature is set to 152℃, the pressure to 1.3MPa, and the holding time to 80 seconds for hot pressing and lamination. After cold pressing and static curing, the composite stone-crystal flooring is obtained. Under these conditions, the lignin-affinity hydrophobic stabilizing impregnating liquid provides a strong hydrophobic barrier. After boiling in water for 4 hours, the thickness expansion rate is 3.1%. The imide-modified amphiphilic hot melt adhesive exhibits high cohesive strength due to its high degree of crosslinking, and its wet heat peel strength is 4.3N / mm, making it suitable for scenarios requiring high dimensional stability. The preparation of the lignin-affinity hydrophobic stabilized impregnation solution includes the following steps: isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, and catalyst are mixed and refluxed at 82°C for 2.5 hours under nitrogen protection. The mixture is then cooled to 42°C, 3,5-dimethylpyrazole is added, and the mixture is stirred for 2.2 hours. Finally, an epoxy-modified acrylic resin solution is added, and the mixture is ultrasonically dispersed to obtain the lignin-affinity hydrophobic stabilized impregnation solution. The mass ratio of isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, catalyst, 3,5-dimethylpyrazole, and epoxy-modified acrylic resin solution is 32:55:13:0.06:5.8:11. The preparation of the imide-modified amphiphilic hot melt adhesive includes the following steps: random copolymer polypropylene, maleic anhydride, and an initiator are melt-grafted at 162°C to obtain an intermediate; the intermediate is dissolved in decahydronaphthalene, isophorone diamine is added dropwise, and the mixture is refluxed to obtain a prepolymer solution containing an amide acid structure; the prepolymer solution is pumped into a twin-screw extruder equipped with a multi-stage devolatilization module, and reactive extrusion is performed in the molten state at 195-215°C; by controlling the shear and residence time of the screw, the anhydride groups are converted in situ to imides. The ring structure involves adding tackifying resin and antioxidant to the feed port at the rear of the extruder for online melt blending. Finally, the solvent and small molecule byproducts generated in the reaction are deeply removed through a multi-stage high-vacuum flash evaporation and degassing section. The resulting product is then directly extruded and granulated to obtain an imide-modified amphiphilic hot melt adhesive. The mass ratio of random copolymer polypropylene, maleic anhydride, and initiator is 100:9:0.25; the mass ratio of intermediate, decahydronaphthalene, isophorone diamine, tackifying resin, and antioxidant is 50:210:4.0:22:0.6.

[0020] In Examples 1-5 and Comparative Examples 1-2, isophorone diisocyanate was from Wanhua Chemical Group Co., Ltd., industrial grade, CAS No.: 4098-71-9; anhydrous ethyl acetate was from Shanghai Aladdin Biochemical Technology Co., Ltd., analytical grade, CAS No.: 141-78-6; hydroxyl-terminated modified silicone oil was hydroxyl-terminated polydimethylsiloxane from Hubei Xinlantian New Materials Co., Ltd., viscosity 1000 cst, CAS No.: 70131-67-8; dibutyltin dilaurate was from Shanghai Maclean Biochemical Technology Co., Ltd., purity 95%, CAS No.: 77-58-7; 3,5-dimethylpyrazole was from Shanghai Aladdin Biochemical Technology Co., Ltd., purity 99%, CAS No.: 67-51-6; epoxy-modified acrylic resin solution was from Jiangsu Sanmu Group Co., Ltd., grade SM-6105, solid content 50%; random copolymer polypropylene was from Sinopec Shanghai Petrochemical Co., Ltd., grade M8. 00E, melt flow rate 10g / 10min; maleic anhydride from Sinopharm Chemical Reagent Co., Ltd., chemically pure, CAS No.: 108-31-6; DCP initiator (dicumyl peroxide) from Shanghai Maclean Biochemical Technology Co., Ltd., purity 98%, CAS No.: 80-43-3; isophorone diamine from Shanghai Aladdin Biochemical Technology Co., Ltd., purity ≥99.0%, CAS No.: 108-91-8; hydrogenated petroleum resin from Eastman, brand name Regalite R1100, CAS No.: 69430-35-9; antioxidant is antioxidant 1010 from BASF, CAS No.: 6683-19-8; commercially available ordinary PUR hot melt adhesive used in Comparative Example 2 from Jowat, model 608.00; stone crystal substrate and solid wood parquet veneer are both commercially available general building materials products; other reagents are all commercially available products.

[0021] Comparative Example 1: This comparative example provides a production process for composite stone-crystal flooring. The only difference is that the solid wood veneer is not treated with a lignin-affinity hydrophobic stabilizing impregnating solution. The remaining steps and the preparation of the imide-modified amphiphilic hot melt adhesive are consistent with those in Example 2. Specifically, the unmodified solid wood parquet veneer, imide-modified amphiphilic hot melt adhesive film, and stone-crystal substrate are directly assembled and hot-pressed. Due to the lack of a hydrophobic stabilizing layer, the natural hydrophilicity of the wood causes it to rapidly absorb water during the boiling water test, resulting in a dramatic volume expansion. After boiling for 4 hours, the thickness expansion rate is as high as 8.5%. The resulting huge shear stress instantly exceeds the adhesive limit of the adhesive layer, leading to interface delamination. The wet heat peel strength is only 1.2 N / mm, which cannot meet the requirements for use in extreme environments.

[0022] Comparative Example 2: This comparative example provides a manufacturing process for composite stone-crystal flooring. The only difference is that commercially available ordinary polyurethane (PUR) hot melt adhesive is used instead of the imide-modified amphiphilic hot melt adhesive of this application. The remaining steps and the preparation of the lignin-affinity hydrophobic stabilizing impregnation solution are consistent with Example 2. During the production process, although the PUR hot melt adhesive initially showed a certain adhesive strength, when subjected to the extreme test of boiling water, the ordinary adhesive layer mainly relies on chemical cross-linking and lacks the synergistic effect of the hydrogen bond dissipation network and imide rigid support unique to the adhesive of this application. As a result, the adhesive layer under hygrothermal cyclic stress undergoes brittle fracture, leading to a significant decrease in the hygrothermal peel strength to 2.5 N / mm. After boiling water for 4 hours, the thickness expansion rate is 3.2%, indicating that the adhesive lacking a dynamic bonding mechanism is difficult to maintain a long-term stable bond between the heterogeneous interface of solid wood and stone-crystal.

[0023] The composite stone-crystal flooring with a solid wood veneer parquet surface prepared in Examples 1-5 and Comparative Examples 1-2 was tested accordingly, and the test results are shown below: (1) Test of resistance to wet heat peel strength The wet heat peel strength of the composite stone-crystal flooring prepared in Examples 1-5 and Comparative Examples 1-2 was measured using a universal testing machine (Instron 5969, USA). The test method referred to the test standard for immersion peel performance in GB / T17657-2013 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The cut specimens were completely immersed in hot water at 63±3℃ for 3 hours, and then dried in a forced-air drying oven at 63±3℃ for 3 hours. This was one cycle. After two consecutive cycles, the peel strength test was performed immediately, and the tensile speed was set to 50 mm / min. Six specimens were selected for each example or comparative example for repeated testing, and the average value of the test results was recorded. The test results are shown in Table 1. Table 1. Test results of the peel strength resistance of composite stone crystal flooring under damp heat.

[0024] As shown in Table 1, the composite stone crystal flooring prepared in this application still maintains excellent interfacial bonding strength after undergoing harsh damp heat cycling. Among them, Example 2 has the highest damp heat peel strength, reaching 4.80 N / mm. With the adjustment of hot pressing process parameters and adhesive formulation, the peel strength showed a trend of first increasing and then decreasing. In Example 2, under moderate hot pressing temperature and pressure, and with a balanced ratio of imide-modified amphiphilic hot melt adhesive, the best interface wetting and chemical bonding were achieved. In contrast, although Example 3 had a high content of hydrophobic components, the excessive crosslinking density led to an increase in the modulus of the adhesive layer, making the material brittle and limiting the stress dissipation ability, resulting in a slight decrease in peel strength to 3.50 N / mm. Compared with Example 2, Comparative Example 1 showed a precipitous drop in peel strength, only 1.20 N / mm. This is because Comparative Example 1 lacked treatment with a lignin-affinity hydrophobic stabilizing impregnating solution. The solid wood veneer underwent severe water absorption and expansion in a humid and hot environment, while the crystalline substrate remained relatively dimensionally stable, resulting in enormous shear stress between the two. When this internal stress exceeded the cohesive strength of the adhesive or the interfacial adhesion, failure occurred. This demonstrates the decisive role of the modified solid wood layer in maintaining interfacial stability in this application. Compared with Example 2, Comparative Example 2 showed that the peel strength decreased to 2.50 N / mm after replacing the imide-modified amphiphilic hot melt adhesive with ordinary PUR hot melt adhesive. The mechanism is that the cross-linked network formed by ordinary PUR adhesive is prone to hydrolysis or brittle fracture under humid and hot conditions. However, the imide-modified amphiphilic hot melt adhesive of this application introduces a rigid cyclic imide structure and polar amide groups through a grafting reaction. These polar groups construct a dense hydrogen bond network between molecular chains. Under humid and hot stress, the hydrogen bond network preferentially dissociates as a sacrificial unit to dissipate energy. After the stress is released, the molecular chains reform physical cross-links through creep. This mechanism, similar to a Velcro closure, effectively avoids brittle fracture caused by stress concentration. In addition, the amphiphilic structure in this hot melt adhesive achieves excellent compatibility with the hydroxyl groups on the wood surface and the lithographic substrate, respectively, constructing a rigid-flexible interface layer.

[0025] (2) Thickness expansion rate test after boiling in water The dimensional stability of the composite stone-crystal flooring prepared in Examples 1-5 and Comparative Examples 1-2 was tested, with a focus on the thickness expansion rate after boiling in water. The test method was based on GB / T18102-2007 "Impregnated Paper Laminate Wood Flooring" and the company's internal control standards. A specimen with a size of 50mm×50mm was cut and its original thickness was measured. The specimen was completely immersed in boiling water for 4 hours, and after being removed and the surface moisture was wiped off, the thickness at the center and four corners was measured again and the average value was calculated. The thickness expansion rate was calculated. Each group of samples was tested three times, and the average value of the data was taken. The test results are shown in Table 2. Table 2 Results of the Thickness Expansion Rate Test for Composite Stone Crystal Flooring After Boiling in Water

[0026] As shown in Table 2, the composite stone crystal flooring prepared in Examples 2, 3, and 5 exhibited excellent dimensional stability, with Example 3 showing particularly outstanding thickness expansion rate of 2.60%. As the proportion of hydrophobic components and crosslinking agents in the lignin-affinity hydrophobic stabilizing impregnation solution increases, the water swelling resistance of the flooring remains stable. Example 3 uses a high content of hydrophobic components and a high variable pressure impregnation pressure, which allows the impregnation solution to penetrate deeper into the cell cavities and cell walls of the wood. From a molecular mechanism perspective, the isocyanate groups in the lignin-affinity hydrophobic stabilizing impregnation solution can chemically react with the hydrophilic hydroxyl groups in wood cellulose, hemicellulose, and lignin to generate carbamate bonds, thereby blocking the main water absorption sites of the wood. At the same time, the hydroxyl-terminated modified silicone oil segments form a hydrophobic shield at the microscopic level, significantly increasing the permeation resistance of water molecules. The thickness expansion rate of Comparative Example 1 was as high as 8.50%, which was much higher than all other examples. This is because the unmodified solid wood veneer retained its natural hygroscopicity. Under boiling water attack, water molecules quickly entered the non-crystalline region of the wood, breaking the hydrogen bonds between molecules and causing the cell walls to swell. This drastic volume change not only damaged the appearance of the flooring, but was also the root cause of the extremely low peel strength of Comparative Example 1 (as shown in Table 1). It is worth noting that although Comparative Example 2 used the same modified solid wood layer as Example 2, its thickness expansion rate was still higher than that of Example 2. This indicates that the integrity of the adhesive layer is also crucial to the overall waterproof performance. The ordinary PUR hot melt adhesive used in Comparative Example 2 developed microcracks or local delamination due to excessive interfacial stress during boiling water, causing water to seep into the bonding surface between the wood and the stone crystal through the adhesive layer defects, resulting in lateral erosion and thus exacerbating the overall water absorption and expansion. In contrast, the imide-modified amphiphilic hot melt adhesive of this application has a significant advantage in maintaining interfacial integrity and plays a certain auxiliary barrier role.

[0027] (3) Surface water contact angle test To visually evaluate the hydrophobic properties of the modified solid wood layer, a contact angle meter (JC2000D, Shanghai Zhongchen Digital Technology Equipment Co., Ltd.) was used to conduct static water contact angle tests on the solid wood layers on the floor surfaces of Examples 1-5 and Comparative Examples 1-2. The seat drop method was used, with 3 μL of deionized water added to the sample surface, and the contact angle value was read 5 seconds after the droplet contacted the surface. Five different locations were selected for measurement on each sample, and the average value was taken. The test results are shown in Table 3. Table 3 Results of water contact angle test on solid wood surface

[0028] As shown in Table 3, the surface water contact angles of Examples (1-5) and Comparative Example 2 treated with lignin-affinity hydrophobic stabilizing impregnation solution all exceeded 100°, exhibiting significant hydrophobic properties. As the content of terminal hydroxyl modified silicone oil and crosslinking agent in the impregnation solution increases, the contact angle shows an upward trend; Example 3 has the largest contact angle because the high content of hydrophobic segments in this formulation is enriched on the surface and in the pores of the wood, which greatly reduces the surface energy of the material. The water contact angle of Comparative Example 1 is only 42.5°, which shows strong hydrophilicity. The untreated solid wood surface contains a large number of polar hydroxyl groups. When water droplets fall, they spread quickly and penetrate into the interior of the substrate. This corresponds to the boiling water expansion rate test results mentioned above, which confirms the instability of natural wood in humid environments. The water contact angle data of Comparative Example 2 and Example 2 are basically the same, about 112°. This is because Comparative Example 2 only changed the type of adhesive, while the modification treatment steps of the solid wood layer were exactly the same as those of Example 2. This result verifies from the side that the impregnation modification process of this application has good reproducibility and stability. However, it can be seen from the data in Tables 1 and 2 that surface hydrophobicity alone is not enough to guarantee the overall performance of the floor. It must be combined with the interfacial stress dissipation mechanism of the imide-modified amphiphilic hot melt adhesive to truly achieve the synergistic protective effect of external water repellency and internal crack resistance. Example 2 achieves the best balance in terms of contact angle, peel strength and dimensional stability through this strategy of combining internal and external protection.

[0029] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments that can be applied to other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A manufacturing process for composite stone-crystal flooring with a surface finish of solid wood veneer parquet, characterized in that, Includes the following steps: The solid wood parquet veneer is placed in a pressure tank and injected with a lignin-affinity hydrophobic stabilizing impregnation solution. After pressure-switching impregnation and gradient temperature drying, a modified solid wood layer is obtained. Imide-modified amphiphilic hot melt adhesive is made into an adhesive film by a casting machine, laid between the stone crystal substrate and the modified solid wood layer, and sent into a hot press. Under the action of an isobaric buffer pad, it is hot-pressed and laminated. After cold pressing and static curing, composite stone crystal flooring is obtained. The preparation of the lignin-affinity hydrophobic stabilizing impregnation solution includes the following steps: Isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil and catalyst were mixed and refluxed at a constant temperature under nitrogen protection. After cooling, 3,5-dimethylpyrazole was added and stirred. Epoxy-modified acrylic resin solution was added and ultrasonically dispersed to obtain the impregnation solution. The preparation of imide-modified amphiphilic hot melt adhesive includes the following steps: Random copolymer polypropylene, maleic anhydride and initiator are melt-grafted to obtain an intermediate; the intermediate is dissolved in decahydronaphthalene, isophorone diamine is added dropwise, and the product after reflux reaction is added to a tackifying resin and an antioxidant, and reactive extrusion is carried out. After removing the solvent by multi-stage vacuum distillation or high vacuum flash evaporation, granulation is performed to obtain a hot melt adhesive.

2. The production process of a composite stone-crystal floor with a solid wood veneer parquet finish as described in claim 1, characterized in that, The mass fractions of isophorone diisocyanate, anhydrous ethyl acetate, hydroxyl-terminated modified silicone oil, catalyst, 3,5-dimethylpyrazole, and epoxy-modified acrylic resin solution are (25-35):(40-60):(5-15):(0.03-0.08):(5.0-6.0):(8-12).

3. The production process of a composite stone-crystal floor with a solid wood veneer parquet finish as described in claim 1, characterized in that, The mass ratio of random copolymer polypropylene, maleic anhydride, and initiator is 100:(6-10):(0.1-0.3); in the preparation of the imide-modified amphiphilic hot melt adhesive, the mass ratio of the intermediate, decahydronaphthalene, isophorone diamine, tackifying resin, and antioxidant is 50:(180-220):(1.0-5.0):(15-25):(0.3-0.8).

4. The production process of a composite stone-crystal floor with a surface of solid wood veneer parquet as described in claim 1, characterized in that, The process conditions for pressure-switching impregnation are: vacuum degree -0.07MPa to -0.09MPa, held for 10-20 minutes; Pressurize to 0.6-1.0 MPa and cycle 2-4 times.

5. The production process of a composite stone-crystal floor with a solid wood veneer parquet finish as described in claim 1, characterized in that, The process conditions for gradient temperature drying are as follows: first dry at 40-50℃ for 1.5-2.5 hours, then dry at 75-85℃ for 0.5-1.5 hours.

6. The production process of a composite stone-crystal floor with a surface of solid wood veneer parquet as described in claim 1, characterized in that, The hot-pressing composite process conditions are: hot-pressing temperature 140-155℃, pressure 3.5-4.5MPa, and holding time 60-120 seconds.

7. The production process of a composite stone-crystal floor with a surface of solid wood veneer parquet as described in claim 1, characterized in that, In the preparation of lignin-affinity hydrophobic stabilized impregnation solution, the constant temperature reflux reaction temperature is 75-85℃ and the time is 2-4 hours; the temperature of the stirring reaction after adding 3,5-dimethylpyrazole is 35-45℃.

8. The production process of a composite stone-crystal floor with a surface of solid wood veneer parquet as described in claim 1, characterized in that, In the preparation of imide-modified amphiphilic hot melt adhesive, the temperature of melt grafting is 155-165℃; the reflux reaction is maintained at a slight boiling state for 1.5-2.5 hours; the temperature of vacuum devolatilization is 175-225℃, and the pressure is -0.08MPa to -0.095MPa.

9. A composite stone crystal floor with a solid wood veneer mosaic surface, prepared using the production process described in any one of claims 1-8.

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