A carbonized flooring and a laminating method thereof

Abstract

The present application relates to the technical field of layered product preparation, and particularly relates to a carbonized floor and a laminating preparation method thereof, which comprises determining the aging stage corresponding to the carbonization degree of a surface plate, analyzing whether the moisture curing degree can meet the demand to adjust the laminating parameters of a laminating machine; detecting the actual deformation amount of the surface plate by applying a test force to the surface plate according to an initial detection period, judging whether the moisture curing degree can meet the curing demand when the required aging stage is lower than the preset aging range, and determining whether to adopt a two-stage laminating mode to perform low-temperature hot pressing on the three-layer plate blank; adjusting the theoretical switching point of the two-stage laminating, determining whether the curing degree of the adhesive between the three-layer plate blanks meets the standard according to the plate blank rebound amount of the theoretical switching point; determining whether to adjust the initial laminating time length of the second stage laminating according to whether the curing degree meets the standard, and adjusting the current initial transportation speed according to the total laminating time length. The present application inhibits the convex deformation of the overall plate blank at the surface layer by matching the carbonization degree of the surface plate and the aging stage of the adhesive.

Description

Technical Field

[0001] This invention relates to the field of layered product preparation technology, and in particular to a carbonized flooring and its lamination preparation method. Background Technology

[0002] Composite flooring, especially products represented by engineered wood flooring and multi-layer engineered wood flooring, has become one of the mainstream choices for modern indoor flooring materials. Its core structure typically consists of a wear layer, a decorative layer, a substrate layer, and a balancing layer, laminated together using a lamination process. Advances in lamination methods directly determine the quality, performance, and cost of flooring products. Traditional composite flooring lamination methods primarily employ a "hot pressing process." The typical process includes: pre-laying (laying the decorative film paper, substrate, balancing layer, etc., in sequence), feeding it into a multi-layer hot press or a continuous flat-press hot press, and maintaining high temperature (usually 160-200°C) and high pressure for a certain period, causing the amino resin (mainly melamine-formaldehyde resin) in the impregnated film paper to melt, flow, and cure, thereby firmly bonding the layers together.

[0003] Chinese Patent Publication No. CN106827115A discloses a continuous lamination method for composite flooring; including (1) selection and preparation of substrate, top plate and bottom plate; (2) application of moisture-curing reactive polyurethane hot melt adhesive to the substrate; (3) assembly: automatic and continuous assembly of the top plate, substrate and bottom plate through a precise positioning device, and direct automatic conveying into a continuous press for cold pressing; (4) continuous room temperature pressure; (5) splitting: the cold-pressed flooring blanks enter a multi-blade saw unit and are split into flooring blanks of equal width; the multi-blade saw is a component of the continuous cold press and is configured after the lamination process. It can be seen that the continuous lamination method for composite flooring has the following problems:

[0004] The moisture content in composite flooring blanks is affected by humidity, moisture movement and evaporation, and the moisture content gradient formed in the blanks leads to surface protrusion, warping and deformation. Summary of the Invention

[0005] Therefore, the present invention provides a carbonized flooring and a method for preparing the same by lamination, in order to overcome the problem of surface protrusion, warping and deformation of composite flooring blanks in the prior art.

[0006] To achieve the above objectives, the present invention provides a method for preparing carbonized flooring laminate, comprising:

[0007] Select the substrate, top plate and bottom plate, apply adhesive to the substrate, predict the equivalent aging degree of the adhesive, determine whether the aging stage of the adhesive before lamination is within the control range, and adjust the preheating parameters or transfer parameters accordingly.

[0008] Stack the top panel, the glued substrate, and the bottom panel in sequence. Determine whether the carbonization degree of the top panel meets the standard based on the change in the brightness value of the top panel, and determine the corresponding required aging degree.

[0009] Based on the required aging degree, determine whether the aging stage corresponding to the adhesive wettability required for the carbonization degree of the surface panel is within the control range, and analyze whether the degree of moisture curing can meet the requirements or adjust the lamination parameters of the laminator.

[0010] According to the initial testing cycle, test force is applied to the surface to detect the actual deformation of the surface. It is determined whether the degree of moisture curing when the required aging stage is lower than the preset aging range can meet the curing requirements, and whether to use a two-stage lamination method to perform low-temperature hot pressing on the three-layer board blank.

[0011] The theoretical switching point of the two-stage lamination is adjusted according to the actual temperature and actual deformation of the slab blank, and the curing degree of the adhesive between the three slab blanks is determined according to the springback of the slab blank at the theoretical switching point.

[0012] Whether to adjust the initial lamination time of the second stage is determined based on whether the degree of curing meets the standard, and the current initial transport speed is adjusted based on the total lamination time;

[0013] Adjust the judgment criteria for whether the degree of moisture curing can meet the requirements based on the humidity adaptability evaluation value of the prepared carbonized floor sample, or reduce the initial detection cycle.

[0014] Furthermore, the process of determining whether the aging stage of the adhesive before lamination is within the controllable range includes:

[0015] Calculate the equivalent aging degree of the adhesive. If the predicted equivalent aging degree is less than the first equivalent value, it is determined that the aging stage of the adhesive is below the control range. Increase the current surface temperature of the board in the preheating stage to accelerate aging.

[0016] When the predicted equivalent aging degree is greater than or equal to the first equivalent value and less than or equal to the second equivalent value, the aging stage of the adhesive is judged to be within the control range.

[0017] When the predicted equivalent aging degree is greater than the second equivalent value, it is determined that the aging stage of the adhesive is out of control, and the initial transportation speed after adhesive application is increased.

[0018] Furthermore, the process of determining whether the carbonization level of the dashboard meets the standard includes:

[0019] When the change in brightness value is within the standard range, the carbonization degree of the panel is judged to be up to standard, and the corresponding required aging degree is determined based on the brightness value.

[0020] When the required degree of aging is lower than the first equivalent value, the aging stage corresponding to the wettability required to determine the degree of carbonization is lower than the control range.

[0021] When the required aging degree is greater than or equal to the first equivalent value and less than or equal to the second equivalent value, the aging stage corresponding to the wettability required to determine the degree of carbonization is within the control range.

[0022] Furthermore, when the required aging stage is below the preset aging range, low-temperature hot pressing is performed according to the initial lamination pressure of the upper layer, the initial lamination pressure of the lower layer, and the initial lamination temperature to analyze whether the degree of moisture curing can meet the requirements.

[0023] When the required aging stage is within the preset aging range, the initial layer pressure of the lower layer of the laminator is adjusted according to the ratio of the required aging degree to the actual aging degree.

[0024] Furthermore, when the adjusted initial lamination pressure of the lower layer is greater than the critical lamination pressure, lamination is performed according to the critical lamination pressure and the initial lamination temperature is increased.

[0025] Further analysis of whether the degree of moisture curing meets the requirements includes:

[0026] During the low-temperature hot pressing process, test force is applied to the panel according to two initial detection cycles to detect the actual deformation of the panel.

[0027] When the ratio of the actual deformation of the panel to the trend of the historical deformation is less than or equal to the evaluation ratio, it is determined that the degree of moisture curing when the required aging stage is lower than the preset aging range can meet the curing requirements.

[0028] When the ratio of the actual deformation of the panel to the trend of the historical deformation is greater than the evaluation ratio, a two-stage lamination method is used to perform low-temperature hot pressing on the panel.

[0029] Furthermore, the process of using a two-stage lamination method to perform low-temperature hot pressing on the board includes:

[0030] The initial lamination time of the first stage of lamination is increased or decreased according to the increase or decrease ratio of the actual temperature of the slab. The initial lamination time of the first stage of lamination is increased according to the ratio of the trend ratio to the evaluation ratio.

[0031] Furthermore, the instantaneous springback of the three-layer board blank when switching from the first stage of lamination to the second stage of lamination is detected, and the instantaneous springback is recorded as the board blank springback amount;

[0032] When the springback of the board exceeds the preset range, it is determined that the curing degree of the adhesive between the three layers of the board is not up to standard, and the initial lamination time of the second stage is increased.

[0033] When the springback of the board blank is lower than the preset range, it is determined that the adhesive between the three layers of the board blank has cured too quickly, resulting in stress storage, and the initial lamination time of the second stage of lamination is reduced.

[0034] The sum of the initial lamination durations of the first and second lamination segments (which are increased or decreased) is recorded as the total lamination duration. The current initial transport speed is then decreased or increased based on the total lamination duration.

[0035] Furthermore, when the humidity adaptation evaluation value is lower than the critical evaluation value, the judgment criteria for whether the degree of moisture solidification can meet the requirements need to be adjusted, and the first equivalent value is increased according to the ratio of the critical evaluation value to the humidity adaptation evaluation value.

[0036] When the humidity adaptation evaluation value is greater than the critical evaluation value, the initial detection cycle is reduced according to the ratio of the critical evaluation value to the humidity adaptation evaluation value.

[0037] A carbonized flooring, comprising a baseboard, a substrate, and a topboard;

[0038] The base plate serves as the bottom layer of the carbonized flooring, the substrate serves as the core layer of the carbonized flooring, and the surface plate serves as the surface layer of the carbonized flooring, wherein the surface plate is a carbonized board.

[0039] The substrate has strip-shaped protrusions on both sides, and strip-shaped recesses are provided on the inner sides of the face plate and the base plate where they need to be bonded. The strip-shaped protrusions of the substrate are embedded in the strip-shaped recesses of the face plate and the base plate.

[0040] An adhesive is used to fill the space between the substrate and the top and bottom plates. The adhesive is a moisture-curing reactive polyurethane hot melt adhesive.

[0041] Compared with the prior art, the beneficial effects of the present invention are that the moisture-curing reactive polyurethane hot melt adhesive is in an initial tack state after cooling, and in a final tack state after the functional groups in the adhesive react chemically with the moisture in the air, and cross-linking and curing to form an ultimate bonding effect with extremely high strength, water resistance, and heat resistance (up to 100°C or above); the structural adhesive application method of this method can save adhesive usage and reduce costs, and avoid the adhesive completely sealing the substrate, which is conducive to the exchange of a small amount of moisture between the floor and the outside world during use.

[0042] Furthermore, with a larger amount of adhesive and a thicker adhesive layer, the internal heat of the adhesive is not easily dissipated, and the heat generated by the curing reaction will accelerate its own curing (autocatalytic effect). In this invention, due to the different required thicknesses of carbonized flooring, and the influence of the thickness variations of the substrate, surface panel, and bottom panel on the amount of adhesive applied, the state of the adhesive is determined by predicting the equivalent aging degree. At the same time, since the degree of carbonization of the surface panel varies, the degree of carbonization determines the difference in hygroscopicity. Excessive carbonization will make it difficult for the adhesive to penetrate. This method reduces the impact of permeability by adjusting the lamination parameters of two-stage lamination or single-stage lamination, and adopts different adjustment strategies according to the degree of carbonization and the aging stage of the adhesive (affected by the amount of adhesive applied) to control the aging degree of the adhesive within a preset range, and performs lamination at the appropriate aging stage of the adhesive or in the initial tack state.

[0043] Furthermore, carbonized flooring is a typical asymmetric functional composite structure. Compared with the bottom layer, the carbonized surface layer has fundamental differences in key properties such as moisture absorption and dimensional change rate. When the surface layer has a high degree of carbonization, poor permeability requires higher adhesive wettability and poses a risk of a weak interface layer. The moisture-curing reactive polyurethane hot melt adhesive (PUR) selected in this invention is characterized by its stronger adaptability to surface energy. Even with poor permeability, extremely high strength can be obtained as long as good surface contact and chemical reaction are achieved. Therefore, lamination can still be carried out at the intermediate aging stage when the carbonization degree is high and permeability is poor, but the degree of moisture curing needs to be analyzed.

[0044] Furthermore, because the carbonization process causes the microporous structure of the wood surface to collapse and close, the carbonized surface board is not easily permeable, which reduces the bonding strength between the adhesive and the board, resulting in bonding differences. This invention judges the degree of carbonization of the surface board based on the change in the lightness value of the current tree species, and determines the required aging of the adhesive for the current degree of carbonization of the surface board. By adjusting the initial lamination pressure of the lower layer, the difference between the required aging degree and the actual aging degree is compensated, increasing the bonding strength between the board and the adhesive. The lamination pressure of the lower layer is limited by increasing the initial lamination temperature, or the initial tack reduction caused by enhanced permeability is analyzed by subsequent moisture curing degree analysis to determine whether the curing degree needs to be adjusted, thus avoiding unstable bonding between the three layers of boards. Adjusting the preheating parameters of the three-layer board before applying the adhesive, or increasing the lamination pressure, can increase the wettability of the adhesive on the board. However, the upper limit of pressure that the carbonized surface board can withstand is reduced. This method selects the change in lightness value to reflect the degree of carbonization, determines whether the permeability of the surface board and the adhesion of the adhesive are matched, and adjusts the initial lamination temperature of the hot press plate to change the aging stage (flowability) of the adhesive to match the permeability of the surface board.

[0045] Furthermore, PUR adhesive cures by reacting with moisture in the air. Carbonized boards have extremely poor hygroscopicity, and their very low surface moisture content slows down the curing reaction at the adhesive interface. Since the chemical conversion rate of PUR adhesive cannot be directly measured online, this method uses the displacement parameters of the strip-shaped concave-convex bonding area under current air humidity and lamination time to reflect the degree of moisture curing within the current pressure period. The deformation of the panel to the test force reflects the curing status of the adhesive between the panel and the substrate. This determines the impact of the aging stage corresponding to the required wettability for the carbonization degree in the pre-processing logic being lower than the preset aging range. Based on the displacement parameters, it determines whether two-stage lamination should be used and whether the degree of moisture curing meets the requirements.

[0046] Furthermore, the purpose of carbonization is to suppress the overall deformation of the board surface. The adhesive's characteristics are that it increases adhesion based on humidity, inhibiting moisture-induced board deformation. The combination of these two aspects requires analysis to determine whether it can meet the adaptability to the application humidity range. This method ensures strong adhesion while releasing and reducing the lamination stress stored in the board by determining the pressure switching sequence of two-stage pressing (curing and shaping stage and stress release stage). When the bonding between the three layers of board is lower than expected, two-stage lamination is used. In the first stage of two-stage lamination, the colloid has initially cross-linked, forming sufficient initial adhesion to resist the rebound tendency of the board caused by internal stress after the pressure is released. The preset theoretical switching point is fine-tuned according to the actual situation of the board (actual temperature and actual deformation). The degree of curing is determined by the amount of board rebound at the theoretical switching point, and the lamination parameters are adjusted accordingly to increase the flexibility of adhesive lamination curing adjustment.

[0047] Furthermore, carbonizing the surface layer aims to comprehensively improve the prepared laminate flooring's tolerance and stability to environmental humidity. This method tests the prepared carbonized flooring and calculates a humidity adaptability evaluation value, reflecting its adaptability to environmental humidity. Based on this humidity adaptability evaluation value, the method adjusts the criteria for determining whether the degree of moisture curing meets requirements, increases adaptability to the aging stage of the adhesive and the degree of surface carbonization, reduces the initial testing cycle for detecting the actual deformation of the surface layer, optimizes the testing frequency reflecting the curing degree between the three layers, and increases the process flexibility of the laminated carbonized flooring. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating the method for laminating carbonized flooring in an embodiment of the present invention.

[0049] Figure 2 This is a schematic diagram of the lamination device in an embodiment of the present invention;

[0050] Figure 3 These are schematic diagrams showing the side view of the carbonized floor and the top view of the substrate in an embodiment of the present invention;

[0051] Figure 4 This is a schematic diagram of the process for determining whether the aging stage of the adhesive is within the control range in an embodiment of the present invention;

[0052] In the diagram: 1-base plate, 2-substrate, 3-surface plate, 4-concave-convex joint area, 5-strip protrusion, 6-piston, 7-lifting base, 8-hot press plate. Detailed Implementation

[0053] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0054] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0055] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0056] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0057] Please see Figures 1-4 As shown, Figure 1 This is a flowchart illustrating the method for laminating carbonized flooring in an embodiment of the present invention. Figure 2 This is a schematic diagram of the lamination device in an embodiment of the present invention; Figure 3 These are schematic diagrams showing the side view of the carbonized floor and the top view of the substrate in an embodiment of the present invention; Figure 4 This is a schematic diagram of the process for determining whether the aging stage of the adhesive is within the control range in an embodiment of the present invention.

[0058] This invention provides a carbonized floor, comprising: a base plate 1, a substrate 2, and a surface plate 3;

[0059] The base plate serves as the bottom layer of the carbonized flooring, the substrate serves as the core layer of the carbonized flooring, and the surface plate serves as the surface layer of the carbonized flooring, wherein the surface plate is a carbonized board.

[0060] The substrate has strip-shaped protrusions 5 on both sides, and strip-shaped recesses are provided on the inner sides of the face plate and the bottom plate that need to be bonded. The strip-shaped protrusions of the substrate are embedded in the strip-shaped recesses of the face plate and the bottom plate.

[0061] An adhesive is used to fill the space between the substrate and the top and bottom plates. The adhesive is a moisture-curing reactive polyurethane hot melt adhesive.

[0062] The area where the strip-shaped protrusions of the substrate are embedded in the strip-shaped recesses of the top and bottom plates is the concave-convex joint area 4.

[0063] This invention provides a method for preparing carbonized flooring laminate, comprising:

[0064] Step S1: Select the substrate, the top plate, and the bottom plate. Place the top plate in the carbonization kiln for high-temperature and low-oxygen heat treatment. The bottom plate serves as the bottom layer, the substrate as the core layer, and the top plate as the surface layer.

[0065] A moisture-curing reactive polyurethane hot melt adhesive is used as an adhesive to apply the adhesive to the substrate in a linear manner. The adhesive is applied to the substrate in a molten state.

[0066] Specifically, adhesive is applied to the substrate in a linear pattern by moving several adhesive application heads. The spacing between the adhesive application heads and the amount of adhesive applied can be adjusted according to requirements.

[0067] Predict the equivalent aging degree of the adhesive, determine whether the aging stage of the adhesive before lamination is within the control range, and adjust the preheating parameters or transfer parameters accordingly.

[0068] Step S2: Stack the top panel, the glued substrate, and the bottom panel in sequence. Determine whether the carbonization degree of the top panel meets the standard based on the change in the brightness value of the top panel, and determine the corresponding required aging degree.

[0069] Step S3: Determine whether the aging stage corresponding to the adhesive wettability required for the carbonization degree of the surface panel is within the control range based on the required aging degree, and analyze whether the degree of moisture curing can meet the requirements or adjust the lamination parameters of the laminator.

[0070] Step S4: Apply test force to the panel according to the initial testing cycle to detect the actual deformation of the panel, determine whether the degree of moisture curing when the required aging stage is lower than the preset aging range can meet the curing requirements, and determine whether to use a two-stage lamination method to perform low-temperature hot pressing on the three-layer board blank.

[0071] Step S5: Adjust the theoretical switching point of the two-stage lamination according to the actual temperature and actual deformation of the board blank, and determine whether the curing degree of the adhesive between the three layers of the board blank meets the standard based on the springback amount of the board blank at the theoretical switching point.

[0072] Step S6: Determine whether to adjust the initial lamination time of the second stage lamination based on whether the curing degree meets the standard, and adjust the current initial transport speed according to the total lamination time.

[0073] Step S7: Adjust the judgment criteria for whether the degree of moisture curing can meet the requirements based on the humidity adaptability evaluation value of the prepared carbonized floor sample, or reduce the initial detection cycle.

[0074] Specifically, the moisture-curing reactive polyurethane hot melt adhesive is in an initial tack state after cooling. After the functional groups in the adhesive react chemically with the moisture in the air, it reaches the final tack state. It cross-links and cures to form an ultimate bonding effect with extremely high strength, water resistance, and heat resistance (up to 100°C or above). This method uses a structural coating method, which can save adhesive usage and reduce costs. On the other hand, it avoids the adhesive completely sealing the substrate, which is conducive to the exchange of trace amounts of moisture between the floor and the outside world during use.

[0075] In this embodiment, the time from the initial tack state to the final tack state of the adhesive is defined as the aging time (open time), and the required thickness of the prepared carbonized floor varies, so the thickness of the selected substrate, top plate and bottom plate also varies accordingly.

[0076] A certain amount of adhesive is applied to the substrate in a linear pattern by moving several adhesive application heads. In this embodiment, the adhesive is a moisture-curing reactive polyurethane hot melt adhesive.

[0077] Calculate the equivalent aging degree of the adhesive In the formula, t is the current actual time from when the glue applicator starts applying glue to when the laminator starts laminating, T is the current surface temperature of the board, RH is the ambient relative humidity (e.g., if the humidity is 50%, then RH=0.5), A is the amount of glue applied, in g / m², k is the correction coefficient, and α, β and γ are the weights of the influence of temperature, humidity and amount of glue applied on the aging rate.

[0078] During implementation, experiments were conducted on the selected adhesives to determine that β is greater than α, greater than γ, and greater than zero. α is the temperature acceleration effect coefficient, β is the humidity acceleration effect coefficient, and γ is the adhesive application amount retardation effect coefficient.

[0079] α represents the degree of influence of temperature on the curing rate of the adhesive, with a reference range of 0.05 ~ 0.15 ℃. -1 β characterizes the effect of ambient relative humidity (RH) on the reaction rate of moisture-curing adhesives, with a reference range of 0.5 to 1.5; γ characterizes the retardation effect of adhesive application amount on the overall curing speed, with a reference range of 0.2 to 0.8; k is an experimentally measured value.

[0080] Specifically, the temperature, humidity, and amount of adhesive applied are systematically varied, and the time required for the adhesive to reach a specific state (e.g., viscosity reaching 5000 mPa·s, or optimal bonding strength) under each condition is measured by substituting several different parameters into the formula. Calculate the reference range for k.

[0081] It is understandable that k, α, β, and γ depend on the specific PUR adhesive formulation and substrate characteristics, and there are no absolutely universal values.

[0082] When the predicted equivalent aging degree is less than the first equivalent value, it is determined that the aging stage of the adhesive is below the control range, and the current surface temperature of the board in the preheating stage is increased to accelerate aging.

[0083] When the predicted equivalent aging degree is greater than or equal to the first equivalent value and less than or equal to the second equivalent value, the aging stage of the adhesive is judged to be within the control range.

[0084] When the predicted equivalent aging degree is greater than the second equivalent value, it is determined that the aging stage of the adhesive is out of control, and the initial transportation speed after the adhesive is applied is increased.

[0085] The first equivalent value is 0.9, and the second equivalent value is 1.1.

[0086] Specifically, with a larger amount of adhesive and a thicker adhesive layer, the internal heat of the adhesive is not easily dissipated, and the heat generated by the curing reaction will accelerate its own curing (autocatalytic effect). In this invention, due to the different required thicknesses of carbonized flooring, and the influence of the thickness variations of the substrate, surface panel, and bottom panel on the amount of adhesive applied, the state of the adhesive is determined by predicting the equivalent aging degree. At the same time, since the degree of carbonization of the surface panel varies, the degree of carbonization determines the difference in hygroscopicity. Excessive carbonization will make it difficult for the adhesive to penetrate. This method reduces the impact of permeability by adjusting the lamination parameters of two-stage lamination or single-stage lamination, and adopts different adjustment strategies according to the degree of carbonization and the aging stage of the adhesive (affected by the amount of adhesive applied) to control the aging degree of the adhesive within a preset range, and performs lamination at the appropriate aging stage of the adhesive or in the initial tack state.

[0087] The top panel, the glued substrate, and the bottom plate are precisely stacked together in sequence using a positioning and stacking equipment. They are then directly and smoothly fed into the laminator via a conveyor belt for low-temperature hot pressing to avoid misalignment.

[0088] Specifically, the laminator includes a piston 6, a lifting base 7, and a hot press plate 8. The hot press plate 8 is connected to the lifting base 7, and the laminator controls the lifting base 7 to move up and down through the piston 6.

[0089] During the lamination process, the top plate is located at the bottom and the bottom plate is at the top, to avoid the temperature and pressure of lamination from top to bottom in this application scenario from having an adverse effect on the carbonized top plate.

[0090] During implementation, strip-shaped protrusions are provided on both sides of the substrate, and strip-shaped recesses are provided on the side (inner side) where the top and bottom plates need to be bonded. When stacked, the strip-shaped protrusions of the substrate are embedded in the strip-shaped recesses of the top and bottom plates.

[0091] When three layers of boards are laminated, the edges, strip protrusions, and strip recesses of each layer are aligned, and the misalignment is controlled within a very small tolerance (such as ±0.5mm). The pressure of the laminator makes each layer of board come into close contact, but too close a contact will crush the wood cells and reduce the moisture curing reaction of the adhesive.

[0092] The adhesive is uniformly flowed and filled between the layers of the board by low-temperature hot pressing under pressure, filling the gaps between the strip-shaped protrusions and depressions between the substrate and the surface and bottom plates.

[0093] In practice, during the low-temperature hot pressing, the temperature range of the hot pressing plate is controlled to be 60°C ~ 80°C.

[0094] Specifically, carbonized flooring is a typical asymmetric functional composite structure. The carbonized surface layer differs fundamentally from the bottom layer in key properties such as moisture absorption and dimensional change rate. When the surface layer is highly carbonized, poor permeability necessitates higher adhesive wettability and poses a risk of a weak interface layer. The moisture-curing reactive polyurethane hot melt adhesive (PUR) selected in this invention is characterized by its stronger adaptability to surface energy. Even with poor permeability, extremely high strength can be achieved as long as good surface contact and chemical reaction are realized. Therefore, lamination can still be performed at the intermediate aging stage even with high carbonization and poor permeability, but the degree of moisture curing needs to be analyzed.

[0095] During carbonization, hemicellulose and cellulose in wood undergo pyrolysis, generating dark-colored carbon-rich substances, which causes the wood color to become darker and more uniform. The lightness (L* value) is highly correlated with the degree of carbonization.

[0096] Use a colorimeter or spectrophotometer to measure the CIE L*a*b* color value of the table surface. When the change range ΔL of the lightness value L* is within the standard range, the carbonization degree of the table is judged to be up to standard. The corresponding required aging degree is determined based on the lightness value L*.

[0097] During implementation, a standard database is established to determine the corresponding degree of carbonization, i.e. the actual degree of carbonization, based on the L* value of the current tree species' surface and the degree of carbonization. The required degree of aging corresponding to the degree of carbonization is obtained, and the change range ΔL = the brightness value of the surface after carbonization - the brightness value of the surface before carbonization.

[0098] When the required degree of aging is lower than the first equivalent value, the aging stage corresponding to the wettability required to determine the degree of carbonization is lower than the control range.

[0099] When the required aging degree is greater than or equal to the first equivalent value and less than or equal to the second equivalent value, the aging stage corresponding to the wettability required to determine the degree of carbonization is within the control range;

[0100] When the required aging stage is below the preset aging range, low-temperature hot pressing is carried out according to the initial layer pressure of the upper layer, the initial layer pressure of the lower layer, and the initial lamination temperature. The degree of moisture curing is analyzed to determine whether it meets the requirements, and the current initial transport speed is adjusted to control the pressing time.

[0101] It is understandable that the current initial transport speed represents both the initial transport speed before and after adjustment.

[0102] When the required aging stage is within the preset aging range, the initial layer pressure of the lower layer of the laminator is adjusted according to the ratio of the required aging degree to the actual aging degree. If the adjusted initial layer pressure of the lower layer exceeds the pressure range corresponding to the degree of carbonization, the initial lamination temperature is increased to compensate.

[0103] In practice, the critical layer pressure corresponding to the degree of carbonization is obtained. When the adjusted initial layer pressure of the lower layer is greater than the critical layer pressure, lamination is performed according to the critical layer pressure and the initial lamination temperature is increased.

[0104] The increased initial lamination temperature = initial lamination temperature + initial lamination temperature × (adjusted initial lamination pressure of the lower layer - the critical lamination pressure) / the critical lamination pressure.

[0105] The standard range is 0-10, and the critical layer pressure is determined by the degree of carbonization corresponding to different brightness values ​​and their corresponding critical pressures. The higher the degree of carbonization, the lower the critical layer pressure.

[0106] In practice, the test specimen can be placed between the pressure plates of the testing machine and pressure perpendicular to the plate surface can be applied at a constant rate (e.g., 1 mm / min). Acoustic emission energy is obtained through acoustic emission sensors, and the characteristic point where the acoustic emission energy / count rate first shows a significant sudden increase is found. The pressure corresponding to the characteristic point is the critical pressure.

[0107] The higher the degree of carbonization of the substrate, the lower the surface energy and the worse the wettability. To improve wetting, the adhesive needs to be in a state of low viscosity and good flowability, that is, when the aging degree is low (shortly after coating) before pressing. However, a low aging degree means that the cohesive force of the adhesive is also very low, resulting in poor initial tack. After the pressure is released from the press, the ability to resist the peeling tendency of the substrate caused by internal stress is correspondingly weakened.

[0108] Specifically, because the carbonization process causes the micropore structure of the wood surface to collapse and close, the carbonized surface board is not easily permeable, which reduces the bonding strength between the adhesive and the board, resulting in bonding differences. This invention judges the degree of carbonization of the surface board based on the change in the lightness value of the current tree species, and determines the required aging of the adhesive for the current degree of carbonization of the surface board. By adjusting the initial lamination pressure of the lower layer, the difference between the required aging degree and the actual aging degree is compensated, increasing the bonding strength between the board and the adhesive. The lamination pressure of the lower layer is limited by increasing the initial lamination temperature, or the initial tack reduction caused by enhanced permeability is analyzed by subsequent moisture curing degree analysis to determine whether the curing degree needs to be adjusted, thus avoiding unstable bonding between the three layers of boards. Adjusting the preheating parameters of the three-layer board before applying the adhesive, or increasing the lamination pressure, can increase the wettability of the adhesive on the board. However, the upper limit of pressure that the carbonized surface board can withstand is reduced. This method selects the change in lightness value to reflect the degree of carbonization, determines whether the permeability of the surface board and the adhesion of the adhesive are matched, and adjusts the initial lamination temperature of the hot press plate to change the aging stage (flowability) of the adhesive to match the permeability of the surface board.

[0109] The process of analyzing the degree of moisture solidification includes:

[0110] During the curing process after the three layers of boards are stacked together, a small, constant shear test force (far below the destructive force) is applied to the surface panel. As the cohesive force of the adhesive layer increases, the ability to resist deformation is enhanced.

[0111] Under the same test force, the displacement will gradually decrease and eventually stabilize. The change curve of this displacement can directly reflect the growth of the cohesive force of the adhesive layer, that is, the degree of curing.

[0112] During implementation, a high-precision laser displacement sensor is used to align with the surface plate in the concave-convex joint area, and its minute displacement is monitored while a test force is applied.

[0113] During the low-temperature hot pressing process, test force is applied to the panel according to two initial detection cycles to detect the actual deformation of the panel.

[0114] When the ratio of the actual deformation of the panel to the trend of the historical deformation is less than or equal to the evaluation ratio, it is determined that the degree of moisture curing when the required aging stage is lower than the preset aging range can meet the curing requirements.

[0115] When the ratio of the actual deformation of the panel to the trend of the historical deformation is greater than the evaluation ratio, the panel is subjected to low-temperature hot pressing using a two-stage lamination method, and the current initial transport speed is adjusted accordingly to control the pressing time.

[0116] Wherein, the historical deformation amount is the historical data of the actual deformation amount generated by the panel under the same test force in the previous initial detection cycle, the trend ratio is the ratio of the actual deformation amount to the historical deformation amount, and the evaluation ratio is a preset value set according to the historical deformation amount data obtained according to the initial detection cycle under the same humidity environment, test force and low temperature hot pressing parameters when the panel is in the preset aging range at the required aging stage.

[0117] Specifically, PUR adhesive cures by reacting with moisture in the air. Carbonized boards have extremely poor hygroscopicity, and their low surface moisture content slows down the curing reaction at the adhesive interface. Since the chemical conversion rate of PUR adhesive cannot be directly measured online, this method uses the displacement parameters of the strip-shaped concave-convex bonding area under current air humidity and lamination time to reflect the degree of moisture curing within the current pressure period. The deformation of the panel to the test force reflects the curing status of the adhesive between the panel and the substrate. This determines the impact of the aging stage corresponding to the required wettability for the carbonization degree in the pre-processing logic being lower than the preset aging range. Based on the displacement parameters, it determines whether two-stage lamination should be used and whether the degree of moisture curing meets the requirements.

[0118] The process of further low-temperature hot pressing of the board using a two-stage lamination method includes:

[0119] A two-stage lamination method is adopted, which is divided into a curing and shaping stage and a stress release stage. The pressure applied in the first stage forces the adhesive to achieve close molecular-level contact with the carbonized surface and eliminates air. In the second stage, the pressure is reduced to maintain the contact state and release the stress between the three layers of boards until the required moisture curing degree is achieved.

[0120] In this application scenario, due to the characteristics of the wood and adhesive, the pressure on the bottom and top panels is different, with the pressure on the bottom being less than that on the top.

[0121] Fine-tune the preset theoretical switching point according to the actual situation of the slab (actual temperature and actual deformation of the slab), and detect the springback of the slab at the theoretical switching point;

[0122] Specifically, the initial lamination time of the first stage is adjusted by decreasing or increasing the actual temperature of the slab, i.e., adjusting the pressure switching sequence of the two lamination stages.

[0123] At the same time, the initial lamination time of the first lamination is increased according to the ratio of the trend ratio to the evaluation ratio.

[0124] The instantaneous springback of the three-layer board blank when switching from the first stage of lamination to the second stage of lamination is detected by a laser sensor, and the instantaneous springback is recorded as the board blank springback amount;

[0125] When the springback of the board exceeds the preset range, it is determined that the curing degree of the adhesive between the three layers of the board is not up to standard, and the initial lamination time of the second stage is increased.

[0126] When the springback of the board blank is lower than the preset range, it is determined that the adhesive between the three layers of the board blank has cured too quickly, resulting in stress storage, and the initial lamination time of the second stage of lamination is reduced.

[0127] During implementation, the sum of the initial lamination times of the first and second lamination stages (which are increased or decreased) is recorded as the total lamination time. The current initial transport speed is then increased or decreased based on the total lamination time.

[0128] When the springback of the slab blank is within the preset range, it is determined that the stress storage of the three-layer slab blank is appropriate, and it is confirmed that the first stage of lamination is switched to the second stage of lamination. The second stage of lamination is carried out according to the initial lamination duration and the current initial transport speed.

[0129] The preset range is a preset value that is adjusted according to the actual thickness of the board, the degree of carbonization of the surface board, and the aging stage of the adhesive.

[0130] Specifically, carbonization aims to suppress surface deformation of the entire board blank. The adhesive's properties increase adhesion based on humidity, inhibiting moisture-induced board blank deformation. The combination of these two methods requires analysis to determine its adaptability to the application humidity range. This method ensures strong adhesion while releasing and reducing the lamination stress stored in the board blank by determining the pressure switching sequence of two-stage pressing (curing and shaping stage and stress release stage). Two-stage lamination is used when the bonding between the three layers of boards is lower than expected. In the first stage of two-stage lamination, the colloid has initially cross-linked, forming sufficient initial tack to resist the rebound tendency of the board due to internal stress after the pressure is released. The preset theoretical switching point is fine-tuned according to the actual situation of the board blank (actual temperature and actual deformation). The degree of curing is determined by the amount of board blank rebound at the theoretical switching point, and the lamination parameters are adjusted accordingly to increase the flexibility of adhesive lamination curing adjustment.

[0131] A portion of the prepared carbonized flooring was taken as a sample to calculate the humidity adaptability evaluation value. The humidity adaptability evaluation value = [(1 - water absorption thickness expansion rate) + equilibrium moisture content stability + (1 - moisture expansion rate) + moisture resistance factor] ÷ 4 × 100%;

[0132] When the humidity adaptation evaluation value is lower than the critical evaluation value, the adjustment needs to analyze whether the degree of moisture solidification can meet the requirements, and increase the first equivalent value according to the ratio of the critical evaluation value to the humidity adaptation evaluation value.

[0133] When the humidity adaptation evaluation value is greater than the critical evaluation value, the initial detection cycle is reduced according to the ratio of the critical evaluation value to the humidity adaptation evaluation value.

[0134] Specifically, equilibrium moisture content stability is a stability score (0-1) assessed based on the variation of the average moisture content of the carbonized flooring under different humidity conditions.

[0135] The water absorption thickness expansion rate is the rate of change in thickness before and after immersion when the sample is soaked in water for a certain period of time. The wet expansion rate is a calculated value based on the dimensional changes of the floor in a specific high humidity environment and a reference dry environment. The smaller the value, the better the stability.

[0136] The moisture resistance factor is the moisture resistance score of the three-layer board, which is 0.85 in this embodiment.

[0137] One embodiment is provided in the implementation, with a water absorption thickness expansion rate of 8% (i.e., 0.08), equilibrium moisture content stability of 0.90, moisture expansion rate of 5% (i.e., 0.05), and a moisture resistance factor of 0.85;

[0138] The calculated humidity adaptation evaluation value is 90.5.

[0139] The critical evaluation value is 85%.

[0140] Specifically, carbonizing the surface layer aims to comprehensively improve the tolerance and stability of the prepared laminate flooring to environmental humidity. This method tests the prepared carbonized flooring and calculates a humidity adaptability evaluation value, reflecting its adaptability to environmental humidity. Based on this humidity adaptability evaluation value, the method adjusts the criteria for judging whether the degree of moisture curing meets the requirements, increases adaptability to the aging stage of the adhesive and the degree of surface carbonization, reduces the initial testing cycle for detecting the actual deformation of the surface layer, optimizes the testing frequency reflecting the degree of curing between the three layers, and increases the process flexibility of the laminated carbonized flooring.

[0141] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0142] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing carbonized flooring laminate, characterized in that, include: S1, Select the substrate, top plate and bottom plate, apply adhesive to the substrate, predict the equivalent aging degree of the adhesive, determine whether the aging stage of the adhesive before lamination is within the control range, and adjust the preheating parameters or transmission parameters accordingly. S2, stack the top panel, the glued substrate and the bottom panel in sequence, and judge whether the carbonization degree of the top panel meets the standard based on the change of the brightness value of the top panel, and determine the corresponding required aging degree. S3, based on the required aging degree, determine whether the aging stage corresponding to the adhesive wettability required for the carbonization degree of the surface panel is within the control range, and analyze whether the degree of moisture curing can meet the requirements or adjust the lamination parameters of the laminator. S4. Apply test force to the panel according to the initial test cycle to detect the actual deformation of the panel, determine whether the degree of moisture curing when the required aging stage is lower than the preset aging range can meet the curing requirements, and determine whether to use a two-stage lamination method to perform low-temperature hot pressing on the three-layer board blank. S5. Adjust the theoretical switching point of the two-stage lamination according to the actual temperature and actual deformation of the board blank, and determine whether the curing degree of the adhesive between the three-layer board blank meets the standard based on the board blank springback at the theoretical switching point. S6, determine whether to adjust the initial lamination time of the second stage lamination based on whether the curing degree meets the standard, and adjust the current initial transport speed according to the total lamination time; S7. Adjust the judgment criteria for whether the degree of moisture curing can meet the requirements based on the humidity adaptability evaluation value of the prepared carbonized floor sample, or reduce the initial detection cycle.

2. The method for preparing carbonized flooring laminate according to claim 1, characterized in that, The process of determining whether the aging stage of the adhesive before lamination is within the control range includes: The equivalent degree of aging of the adhesive is calculated based on the current actual time from gluing to lamination, the current surface temperature of the board, the relative humidity of the environment, the amount of adhesive applied, and the weights of the effects of temperature, humidity, and amount of adhesive on the aging rate. When the predicted equivalent aging degree is less than the first equivalent value, it is determined that the aging stage of the adhesive is below the control range, and the current surface temperature of the board in the preheating stage is increased to accelerate aging. When the predicted equivalent aging degree is greater than or equal to the first equivalent value and less than or equal to the second equivalent value, the aging stage of the adhesive is judged to be within the control range. When the predicted equivalent aging degree is greater than the second equivalent value, it is determined that the aging stage of the adhesive is out of control, and the initial transportation speed after the adhesive is applied is increased. The first equivalent value is 0.9, and the second equivalent value is 1.

1.

3. The method for preparing carbonized flooring laminate according to claim 2, characterized in that, The process of determining whether the carbonization level of the dashboard meets the standard includes: When the change in brightness value is within the standard range, the carbonization degree of the panel is judged to be up to standard, and the corresponding required aging degree is determined based on the brightness value. When the required degree of aging is lower than the first equivalent value, the aging stage corresponding to the wettability required to determine the degree of carbonization is lower than the control range. When the required aging degree is greater than or equal to the first equivalent value and less than or equal to the second equivalent value, the aging stage corresponding to the wettability required to determine the degree of carbonization is within the control range.

4. The method for preparing carbonized flooring laminate according to claim 3, characterized in that, When the required aging stage is below the preset aging range, low-temperature hot pressing is performed according to the initial lamination pressure of the upper layer, the initial lamination pressure of the lower layer, and the initial lamination temperature to analyze whether the degree of moisture curing can meet the requirements. When the required aging stage is within the preset aging range, the initial layer pressure of the lower layer of the laminator is adjusted according to the ratio of the required aging degree to the actual aging degree.

5. The method for preparing carbonized flooring laminate according to claim 4, characterized in that, When the initial lamination pressure of the adjusted lower layer is greater than the critical lamination pressure, lamination is performed according to the critical lamination pressure and the initial lamination temperature is increased.

6. The method for preparing carbonized flooring laminate according to claim 5, characterized in that, The process of analyzing whether the degree of moisture curing meets the requirements includes: During the low-temperature hot pressing process, test force is applied to the panel according to two initial detection cycles to detect the actual deformation of the panel. When the ratio of the actual deformation of the panel to the trend of the historical deformation is less than or equal to the evaluation ratio, it is determined that the degree of moisture curing when the required aging stage is lower than the preset aging range can meet the curing requirements. When the ratio of the actual deformation of the panel to the trend of the historical deformation is greater than the evaluation ratio, a two-stage lamination method is used to perform low-temperature hot pressing on the panel.

7. The method for preparing carbonized flooring laminate according to claim 6, characterized in that, The process of using a two-stage lamination method to perform low-temperature hot pressing on the board includes: The initial lamination time of the first stage of lamination is increased or decreased according to the increase or decrease ratio of the actual temperature of the slab. The initial lamination time of the first stage of lamination is increased according to the ratio of the trend ratio to the evaluation ratio.

8. The method for preparing carbonized flooring laminate according to claim 7, characterized in that, The instantaneous springback of the three-layer board blank is detected when the first stage of lamination is switched to the second stage of lamination, and the instantaneous springback is recorded as the board blank springback amount; When the springback of the board exceeds the preset range, it is determined that the curing degree of the adhesive between the three layers of the board is not up to standard, and the initial lamination time of the second stage is increased. When the springback of the board blank is lower than the preset range, it is determined that the adhesive between the three layers of the board blank has cured too quickly, resulting in stress storage, and the initial lamination time of the second stage of lamination is reduced. The sum of the initial lamination durations of the first and second lamination segments (which are increased or decreased) is recorded as the total lamination duration. The current initial transport speed is then decreased or increased based on the total lamination duration.

9. The method for preparing carbonized flooring laminate according to claim 8, characterized in that, When the humidity adaptation evaluation value is lower than the critical evaluation value, the adjustment needs to analyze whether the degree of moisture solidification can meet the requirements, and increase the first equivalent value according to the ratio of the critical evaluation value to the humidity adaptation evaluation value. When the humidity adaptation evaluation value is greater than the critical evaluation value, the initial detection cycle is reduced according to the ratio of the critical evaluation value to the humidity adaptation evaluation value.

10. A carbonized flooring prepared according to the carbonized flooring lamination preparation method according to any one of claims 1-9, characterized in that, Includes base plate, substrate, and surface plate; The base plate serves as the bottom layer of the carbonized flooring, the substrate serves as the core layer of the carbonized flooring, and the surface plate serves as the surface layer of the carbonized flooring, wherein the surface plate is a carbonized board. The substrate has strip-shaped protrusions on both sides, and strip-shaped recesses are provided on the inner sides of the face plate and the base plate where they need to be bonded. The strip-shaped protrusions of the substrate are embedded in the strip-shaped recesses of the face plate and the base plate. An adhesive is used to fill the space between the substrate and the top and bottom plates. The adhesive is a moisture-curing reactive polyurethane hot melt adhesive.

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