A process for softening a surface paper

Abstract

The application discloses a kind of veneer softening treatment process, belong to decorative board processing technical field.The process includes: the original paper is dipped modified melamine resin and is dried to pre-curing degree 25~35%;Based on the paper grammage and fiber density, dilution model is established, and softening agent is coated using micro-concave roller coating technology;80 ℃, 130 ℃, 90 ℃ three-stage drying is performed;Under the condition of 25±2 ℃, 60±5%RH, it is placed for 24~48 hours;After being paved with bottom non-woven fabric and substrate, infrared preheating is carried out;Gradient hot pressing including closed period, curing period and setting period is implemented;After pressing, it is placed for more than 48 hours.The application realizes the synergic control of accurate coating of softening agent and gradient hot pressing, effectively solves the problems of uneven coating, hot pressing defects and internal stress concentration, and significantly improves the product yield and surface quality.

Description

Technical Field

[0001] This invention relates to the field of decorative board processing technology, specifically to a softening process for decorative paper. Background Technology

[0002] As the decoration and renovation industry moves towards high-end and personalized products, consumers are demanding increasingly stringent requirements for the three-dimensionality and texture of decorative papers (such as melamine-impregnated paper). In particular, the widespread adoption of high-end processes such as deep embossing and synchronized pattern matching requires decorative papers to possess excellent flexibility and extensibility to adapt to the complex textures of the substrate surface.

[0003] However, there are still many insurmountable technical bottlenecks in the existing finishing paper softening process, which seriously restrict the improvement of product yield and quality.

[0004] Poor uniformity and difficulty in penetrating softener coating: Traditional processes often use curtain or spray methods to apply softener, which makes it difficult to precisely control the coating amount. Due to the lack of differentiated sizing models for different paper types (such as high-density white solid-color paper and loose wood grain paper), uneven softener distribution is common. For white paper, insufficient softener penetration leads to poor resin flow, resulting in "dried flowers" or "white spots" after lamination; while for wood grain paper, excessive softener can damage paper strength, causing tensile deformation or even breakage during lamination.

[0005] Hot-pressing process parameters, when fixed, cannot adapt to the resin's rheological properties: Existing hot-pressing processes typically use a single temperature and pressure profile. The introduction of a softener alters the resin's melt flow window. Traditional fixed-parameter hot-pressing cannot provide sufficient flow time for the resin to fill the embossing mold during the curing phase, resulting in "shrinkage marks" or "unclear embossing" on the board surface. Furthermore, during the curing period, excessively rapid temperature increases or sudden pressure drops can easily prevent volatiles from escaping, leading to internal blistering or surface "wet spots / haze."

[0006] Incomplete stress relief: The expansion coefficients of the veneer paper and the wood substrate are different. In existing processes, due to the lack of an effective intermediate stress buffer layer and sufficient curing after pressing, the board is prone to internal stress concentration in subsequent processing or use environments, resulting in board warping, surface micro-cracks (crazing), and insufficient interlayer peel strength.

[0007] In summary, there is an urgent need for a paper softening process that can achieve precise application of softening agents and combine gradient hot pressing with stress control to solve the problems of uneven coating, poor leveling and internal stress defects, thereby producing high-quality decorative boards with no defects and high flexibility. Summary of the Invention

[0008] The purpose of this invention is to provide a softening process for decorative paper to solve the defects such as product cracking, dry spots, and delamination caused by uneven coating of softening agent and mismatch of hot pressing parameters in the prior art, thereby improving the yield and surface quality of softened decorative paper products.

[0009] A paper softening process includes the following steps: S101: Obtain the raw paper; S102: The base paper is impregnated with modified melamine resin and dried to achieve a pre-curing degree of 25% to 35%. If the pre-curing degree is below 25%, the resin is prone to excessive flow during subsequent coating of softener and drying, resulting in a sticky surface. If it is above 35%, the resin cross-linking is too high, the molecular chain segment mobility is limited, which will hinder the penetration and swelling effect of the softener, thereby weakening the softening effect.

[0010] S103: A dilution model is established based on paper basis weight and fiber density, and a micro-gravure coating technology is used to coat the paper surface with a softener according to this model. Micro-gravure coating, through a precise anilox roller and doctor blade system, can achieve an ultra-thin and uniform coating. Combining the dilution model based on basis weight (which determines the total amount of fiber per unit area) and fiber density (which determines the paper's compactness and porosity), the penetration depth and surface film amount of the softener can be dynamically adjusted. For high basis weight and high density paper, the model can automatically reduce the dilution ratio to increase the driving force of softener penetration; conversely, it can increase the dilution ratio to prevent excessive penetration from damaging the paper strength, thereby achieving precise application in a "tailor-made" manner.

[0011] S104: Perform a three-stage drying process on the coated paper, wherein the temperature ranges for the three stages of drying are 80°C, 130°C, and 90°C respectively; this stage adopts a three-stage drying process of "low temperature-high temperature-low temperature". The first stage of low temperature (80°C) is intended to slowly evaporate the diluted solvent in the softener to prevent rapid film formation on the surface and the formation of a closed layer that hinders the escape of internal moisture; the second stage of medium-high temperature (130°C) is used to quickly remove most of the free water and initially induce the reaction between the resin and the softener; the third stage of cooling (90°C) is to make the temperature and moisture content of the paper inside and on the surface more uniform, eliminate the internal stress caused by rapid drying, and avoid paper curling or embrittlement.

[0012] S105: Place the dried softened paper in a constant temperature and humidity environment for 24 to 48 hours, with the ambient temperature controlled at 25±2℃ and the humidity at 60±5%. Under these constant temperature and humidity conditions, the residual softener molecules continue to diffuse and distribute evenly into the amorphous regions of the fibers through the concentration gradient. Simultaneously, the residual stress generated during drying within the paper is fully relaxed. This ensures that all parts of the paper deform synergistically during subsequent lamination, making it a crucial pretreatment to suppress cracking and microcracks.

[0013] S106: The softened decorative paper, after being left to stand, is laid with a bottom non-woven fabric and a substrate with a moisture content controlled at 6%±1% to obtain a board blank. The bottom non-woven fabric serves as a stress buffer layer, and its porous structure can absorb the shear stress generated by the difference in thermal expansion coefficients between the decorative paper and the substrate. The moisture content of the substrate is strictly controlled at 6%±1%, which is close to the final equilibrium moisture content of the decorative paper, minimizing dimensional changes caused by moisture absorption / desorption and reducing the risk of warping from the source.

[0014] S107: The surface of the slab is preheated with infrared radiation to a temperature of 40°C to 50°C. Infrared preheating has the characteristics of penetration and selective heating, which can quickly and uniformly raise the temperature of the slab surface layer, so that it enters the viscoelastic state before entering the hot press, thereby shortening the heating time of the hot pressing closure period, gaining more effective time for resin flow, and reducing temperature fluctuations in the hot press.

[0015] S108: Gradient hot pressing is applied to the preheated slab, wherein the gradient hot pressing includes a closing period, a curing period and a shaping period in sequence; gradient hot pressing decomposes the traditional single-stage pressing into three functionally distinct stages.

[0016] Closing period: Under relatively low temperature and pressure conditions, the molten resin is fully impregnated and filled into the embossed pattern, and interlayer air is eliminated; Curing period: Increasing temperature and pressure triggers a deep cross-linking reaction between the resin and the softener, forming a stable three-dimensional network structure; Shaping period: Cooling under pressure to fix the shape of the sheet material and prevent internal stress or deformation caused by rapid cooling.

[0017] S109: After pressing, the boards are stacked and left to stand for more than 48 hours. This stacking and standing process after pressing is a secondary curing process. During this process, the interior of the board transitions from a non-equilibrium state under high temperature and pressure to an equilibrium state under normal temperature and pressure, further releasing the residual stress generated by hot pressing, stabilizing the final dimensions and mechanical properties of the board, and is a necessary process to ensure that the product does not warp or crack during long-term use.

[0018] Preferably, when applying the softener in step S103, the amount of softener applied is controlled at 12-18 g / m² (dry weight), and the application amount error is ≤ ±1 g / m².

[0019] Preferably, during the laying process in step S106, the surface roughness Ra of the substrate is less than 10 μm, and a layer of modified nonwoven fabric or high-permeability balancing paper is added between the decorative paper and the substrate as a stress buffer layer.

[0020] Preferably, the specific parameters of the gradient hot pressing in step S108 are as follows: Closing period: temperature 110-120℃, pressure 1.5-2.0MPa; Curing period: temperature rise to 160-180℃, pressure increase to 3.0-3.5MPa; Shaping period: cooling and pressure holding.

[0021] Preferably, for deep embossed products, a brief vacuum pumping process is introduced during the closing period of step S108 to remove interlayer air.

[0022] Preferably, when dried flower / white spot defects occur, the low-pressure time of the closing period is extended by 10-15 seconds or the curing temperature is reduced by 5-10°C.

[0023] Preferably, when applying the softener in step S103, a differentiated formula is set for different types of paper: a high-penetration softener formula is used for white / solid-color paper, and a high-viscosity softener formula is used for wood grain paper.

[0024] Preferably, the establishment of the dilution model in step S103 specifically involves calculating the dilution ratio of the softener based on the basis weight and fiber density of the base paper.

[0025] Preferably, the bottom nonwoven fabric used in step S106 is a highly breathable nonwoven fabric with a basis weight of 30-50 g / m².

[0026] Preferably, in step S102, when impregnating and drying the modified melamine resin, the resin solid content is controlled at 45-50% and the viscosity is controlled at 200-400 cps.

[0027] Compared with the prior art, the paper softening process provided by the present invention has the following beneficial effects: 1. This process achieves highly uniform coating of the softener by precisely controlling the pre-curing degree of the resin to 25%-35%, combined with micro-grooved roller coating and a dilution model based on basis weight and fiber density, fundamentally solving the surface quality defects caused by uneven coating. At the same time, the three-stage drying process of "low temperature-high temperature-low temperature" and the constant temperature and humidity curing process work together to ensure that the softener fully penetrates and the resin is moderately cured, giving the paper excellent flexibility and dimensional stability, while avoiding stress accumulation caused by excessively rapid surface drying or internal moisture drying.

[0028] Gradient hot pressing, combined with infrared preheating and a stress buffer layer, allows the resin to flow and impregnate fully during the closing period, achieves full cross-linking during the curing period, and effectively maintains the shape of the board during the setting period, significantly suppressing defects such as surface cracking, delamination, and bubbling.

[0029] 2. This process significantly improves product yield and surface quality under complex process conditions by introducing vacuum extraction for deep embossed products and adjusting dynamic parameters for dried flower / white spot defects. At the same time, this process establishes differentiated softener formulations according to different paper types, broadening the scope of application of the process, enabling both white / solid color paper and wood grain paper to obtain ideal flexibility and surface effects, and reducing overall production costs. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the process flow for a specific embodiment of the present invention. Detailed Implementation

[0031] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0033] Furthermore, it should be understood in the description of this application that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0034] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0036] Example 1: Softening and pressing of wood grain paper like Figure 1 As shown, the following is the specific process flow for softening this decorative paper: S101: Obtain wood grain base paper with a basis weight of 80 g / m² and a fiber density of 0.65 g / cm³. This wood grain base paper is made of wood fibers with a fiber length in the range of 0.8~2.5 mm, a paper density of 0.65 g / cm³, and a surface smoothness of 120 seconds (Bekk method).

[0037] S102: The base paper is impregnated with modified melamine resin (solid content 48%, viscosity 300cps), and dried in a multi-stage oven. The oven temperatures are set as follows: first stage 100℃, second stage 120℃, third stage 110℃, and the drying speed is 8m / min, so that the pre-curing degree of the resin reaches 30%. This pre-curing degree is determined by measuring the free formaldehyde content in the resin and converting it into the degree of crosslinking.

[0038] S103: A dilution model was established based on paper basis weight and fiber density. The softener concentrate and diluent were mixed at a volume ratio R = 0.2 × (basis weight / fiber density), resulting in R = 0.2 × (80 / 0.65) ≈ 24.6:1. This diluted solution was adjusted to a suitable coating viscosity. Next, micro-grooving technology was used, selecting a micro-grooving roller with 350 lines of aniloxane to uniformly coat the high-viscosity softener onto the paper surface. The coating amount was controlled at 15 ± 0.8 g / m² (dry weight). After coating, an infrared thickness gauge was used to detect the coating uniformity online, ensuring that the coating amount error was ≤ ± 1 g / m².

[0039] S104: Immediately after coating, the paper undergoes a three-stage drying process: the first stage is surface pre-drying at 80℃ (oven temperature 80℃, air velocity 0.5m / s, drying time 15 seconds); the second stage is rapid moisture removal at 130℃ (oven temperature 130℃, air velocity 0.8m / s, drying time 20 seconds); and the third stage is moisture content equalization at 90℃ (oven temperature 90℃, air velocity 0.3m / s, drying time 12 seconds). The moisture content of the dried paper is controlled between 8% and 10%.

[0040] S105: Place the dried softened paper in a constant temperature and humidity room and let it stand for 36 hours at 25℃ and 60%RH. During the standing period, the paper should be laid flat on a clean stainless steel tray, with breathable paper between the layers, not exceeding 10 layers, to ensure air circulation.

[0041] S106: The substrate is medium-density fiberboard (MDF) with a density of 0.68 g / cm³, sanded to a roughness of Ra=8μm, and the moisture content is controlled at 6.2%. A layer of highly breathable modified nonwoven fabric with a basis weight of 40 g / m² is laid between the softened decorative paper and the substrate as a stress buffer layer. This nonwoven fabric is a polyester fiber needle-punched nonwoven fabric with a porosity ≥85%. The board blank is obtained after the laying is completed.

[0042] S107: The surface of the slab is uniformly preheated by an infrared heating plate. The infrared wavelength is selected as 2~5μm medium-wave infrared, the power density is 0.8kW / m², and the preheating time is 8 seconds, so that the temperature of the slab reaches 45℃.

[0043] S108: The preheated slab is fed into the press for gradient hot pressing. Closure period: Set temperature 115℃, pressure 1.8MPa, time 20 seconds. During this stage, the resin melts and begins to flow, and the softener promotes fiber softening, together filling the fine structure of the embossing mold. Curing period: Heat to 170℃, pressure to 3.2MPa, and hold for 50 seconds. During this stage, the resin and softener undergo a deep cross-linking and curing reaction to form a stable adhesive layer. Setting period: Under pressure, cooling water is circulated to reduce the temperature of the pressure plate to below 80°C, with the cooling rate controlled at 1.5°C / second, and then the pressure is released and the plate is removed.

[0044] S109: After pressing, the boards are stacked and left to stand at room temperature (25±2℃) for 50 hours to eliminate residual stress and stabilize dimensions. Wood grain veneer panels produced using this process have no cracks or white spots on the surface, and the bonding strength and flexibility meet the requirements for deep embossing.

[0045] Example 2: Softening treatment of white solid color paper The difference from Example 1 is that: In step S101, a white solid-color base paper is obtained. The base paper has a basis weight of 75 g / m² and a fiber density of 0.72 g / cm³ (higher than wood grain paper, indicating that the paper is more compact).

[0046] In step S103, a high-penetration softener formulation is used for white solid-color paper. This involves adding an appropriate amount of penetration aid (such as surfactant OP-10, at 3% of the softener's mass) to the softener stock solution to reduce its surface tension and improve its penetration ability in high-density paper. The coating amount is controlled at 13 g / m² (dry weight), and the dilution model is used to adjust the coefficient R = 0.2 × (75 / 0.72) ≈ 20.8:1 to ensure effective penetration of the softener even under high-density paper conditions.

[0047] During hot pressing in step S108, the closing time is extended to 30 seconds (10 seconds longer than in Example 1) to avoid white spots. The curing temperature is appropriately reduced to 165°C (5°C lower than in Example 1) to prevent the white paper from yellowing or showing hazy defects due to excessive temperature.

[0048] The other steps are the same as in Example 1. The resulting product has a uniform surface color, no haze, dried flowers or other defects, and good flexibility.

[0049] Example 3: Special treatment for deep embossed products This embodiment is specifically designed for deep embossed products (embossing depth ≥ 0.5 mm).

[0050] Steps S101 to S107 are the same as in Example 1.

[0051] In step S108, a vacuum pumping process of 5-8 seconds is introduced at the beginning of the closure period, with the vacuum level controlled at -0.08MPa, to remove residual air between layers and effectively prevent stratification and bubbling caused by gas accumulation under high pressure. The vacuum pumping is carried out during the low-pressure stage (1.8MPa) of the closure period, and the pressure is immediately restored to 1.8MPa after the pumping is completed to continue the closure period.

[0052] The closing period is set at a temperature of 115℃ and a pressure of 1.8MPa. After vacuuming for 5 seconds, the pressure is maintained for another 15 seconds (total 20 seconds). During the curing period, the temperature was increased to 170°C and the pressure was increased to 3.2 MPa, and held for 55 seconds (5 seconds longer than in Example 1 to compensate for the pressure loss during the vacuum pumping stage). During the shaping period, cooling water is circulated under pressure to reduce the temperature of the pressure plate to below 80°C, with the cooling rate controlled at 1~2°C / second, and then the pressure is released and the plate is removed.

[0053] Step S109 is the same as in Example 1.

[0054] Meanwhile, if localized dry flower or white spot defects are found during inspection, the low-pressure time of the closing period is dynamically extended by 12 seconds or the curing temperature is reduced by 8°C for online correction.

[0055] Products made using this process have clear embossing, no bubbles, no delamination, and excellent surface quality.

[0056] Example 4: Adaptation to different substrates This embodiment verifies the adaptability of the process of the present invention to different substrates.

[0057] Steps S101 to S105 are the same as in Example 1.

[0058] In step S106, the substrate is selected as particleboard (density 0.65 g / cm³), surface roughness Ra=9 μm, and moisture content controlled at 5.8%. A layer of highly breathable balancing paper with a basis weight of 35 g / m² is laid between the decorative paper and the particleboard as a stress buffer layer (alternative to the modified nonwoven fabric in the embodiment).

[0059] Steps S107 to S109 are the same as in Example 1.

[0060] The resulting product bonds well with the particleboard substrate, with a bonding strength of over 0.45 MPa, and exhibits no delamination or warping.

[0061] This embodiment demonstrates that the process of the present invention is not only applicable to MDF substrates, but also to other wood substrates such as particleboard, and has good versatility.

[0062] Comparative Example 1: Pre-curing degree is not within the preferred range This comparative example uses basically the same process parameters as Example 1, except that the resin pre-curing degree is controlled at 18% in step S102 (lower than the preferred range of 25%~35% of the present invention).

[0063] Due to insufficient pre-curing, the resin flowed excessively during subsequent coating of the softener and drying process, causing a large amount of resin to migrate to the paper surface, forming obvious "glue spot" defects. After lamination, the board surface exhibited large-area stickiness, with a bonding strength of only 0.28 MPa, far lower than the 0.52 MPa of Example 1. Simultaneously, the excessive resin flow resulted in severely uneven resin distribution between the paper surface and interior, leading to multiple "dry spots" and "white spots" defects on the surface after lamination, resulting in a product yield of only 72%.

[0064] This comparative example illustrates that when the pre-curing degree is less than 25%, the rheological behavior of the resin is out of control, and high-quality products cannot be obtained.

[0065] Comparative Example 2: Excessive Pre-curing This comparative example uses basically the same process parameters as Example 1, except that the resin pre-curing degree is controlled at 40% in step S102 (which is higher than the preferred range of 25%~35% of the present invention).

[0066] Due to excessive pre-curing and resin cross-linking, the mobility of molecular chain segments was limited. During subsequent application of the softener, the softener molecules struggled to penetrate the amorphous regions of the fibers, resulting in a significant decrease in softening effect. Multiple microcracks (crazing) appeared on the surface of the board after lamination, and it broke after bending 180° in the flexibility test. The bond strength was 0.35 MPa, lower than the 0.52 MPa of Example 1. The product yield was only 78%.

[0067] This comparative example illustrates that when the pre-curing degree is higher than 35%, the cross-linking network of the resin is too dense, which hinders the penetration and swelling effect of the softener and fails to achieve the desired softening effect.

[0068] Comparative Example 3: No dilution model used (uniform coating amount) This comparative example uses essentially the same process parameters as Example 1. The difference is that in step S103, a dilution model based on paper weight and fiber density is not used. Instead, a uniform amount of softener coating (15g / m²) and a uniform dilution ratio are used for all types of paper.

[0069] For the wood grain paper (80 g / m², fiber density 0.65 g / cm³) in Example 1, a uniform coating amount yielded good results, with a product yield of approximately 85%. However, when the same process parameters were applied to white solid-color paper (75 g / m², fiber density 0.72 g / cm³), the uniformly high coating amount resulted in insufficient penetration of the softener due to the denser structure of the white paper. Consequently, numerous "dried flowers" and "white spots" appeared on the surface, reducing the product yield to 65%.

[0070] This comparative example illustrates that without using a dilution model based on paper weight and fiber density, it is impossible to achieve uniform coating and penetration of softener between different paper types, which seriously affects product quality.

[0071] Comparative Example 4: No gradient hot pressing (single-stage hot pressing) This comparative embodiment uses essentially the same process parameters as Embodiment 1, except that step S108 uses single-stage hot pressing (constant temperature 180℃, constant pressure 2.5MPa, time 70 seconds) instead of the gradient hot pressing described in this invention.

[0072] Under single-stage hot pressing, the resin melted rapidly due to the excessively high temperature during the closing phase (180°C), but the flow time was insufficient, resulting in inadequate embossing and defects such as "shrinkage marks" and "unclear embossing" on the surface. Simultaneously, due to the excessively rapid temperature rise during the curing period, volatiles could not be discharged in time, leading to multiple blistering issues within the board. The product yield was only 75%, and both surface quality and internal bonding strength were significantly lower than in Example 1.

[0073] This comparative example illustrates that without the gradient hot pressing process, it is impossible to match the changes in resin rheological properties after the introduction of a softener, resulting in unsatisfactory product surface quality and internal structure.

[0074] Comparative Example 5: Insufficient post-pressing settling time This comparative embodiment uses basically the same process parameters as Embodiment 1, except that the stacking and settling time after pressing in step S109 is only 24 hours (lower than the preferred 48 hours of this invention).

[0075] Insufficient post-press settling time resulted in the incomplete release of residual stress within the board. Microcracks (crazing) began to appear on the board surface on days 2-3 after pressing, and by day 7, the warping deformation reached 3.2 mm / m, far exceeding the 0.5 mm / m of Example 1. The bond strength was 0.48 MPa after 24 hours of settling, while Example 1 reached over 0.52 MPa after 50 hours of settling.

[0076] This comparative example illustrates that a post-compression stacking settling time of more than 48 hours is necessary to fully release residual stress and ensure the long-term dimensional stability of the product.

[0077] Experimental results verification: To verify the effectiveness of the process of the present invention, decorative panel samples were prepared according to the process parameters of Examples 1-4 and Comparative Examples 1-5, and the following performance tests were performed: The test items included: surface quality (visual inspection for defects such as cracks, white spots, and bubbles), bond strength (GB / T17657-2013), flexibility (180° bending test), and warpage (measured after 7 days of standing). The test results are shown in the table below:

[0078] The test results show that the products of each embodiment of the present invention are significantly superior to those of the comparative embodiments in key indicators such as surface quality, bonding strength, flexibility, warpage, and yield. In particular, the yield of products in embodiments 1-4 is all above 93%, while the yield of comparative embodiments is below 78%, which fully demonstrates the significant technical effect brought about by the synergistic effect of the various technical features of the present invention.

[0079] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0080] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0081] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A softening process for decorative paper, characterized in that, Includes the following steps: S101: Obtain the raw paper; S102: Impregnate the base paper with modified melamine resin and dry it to achieve a pre-curing degree of 25% to 35%. S103: A dilution model is established based on paper basis weight and fiber density, and a softener is coated on the paper surface using micro-grooved roller coating technology according to the model. S104: Perform a three-stage drying process on the coated paper, wherein the temperature ranges of the three-stage drying process are 80°C, 130°C and 90°C respectively. S105: Place the dried softened paper in a constant temperature and humidity environment for 24 to 48 hours, wherein the ambient temperature is controlled at 25±2℃ and the humidity is controlled at 60±5%; S106: The softened decorative paper after standing is laid with the bottom non-woven fabric and the substrate with a moisture content controlled at 6%±1% to obtain the slab blank; S107: Preheat the surface of the slab with infrared radiation to bring its temperature to 40°C to 50°C; S108: Gradient hot pressing is applied to the preheated slab, wherein the gradient hot pressing includes a closing period, a curing period and a shaping period in sequence; S109: After pressing, the boards are stacked and left to stand for more than 48 hours.

2. The paper softening process according to claim 1, characterized in that, When applying the softener in step S103, the amount of softener applied is controlled at 12-18 g / m² (dry weight), and the application error is ≤ ±1 g / m².

3. The paper softening process according to claim 1, characterized in that, During the laying process in step S106, the surface roughness of the substrate Ra is less than 10 μm, and a layer of modified nonwoven fabric or high-permeability balancing paper is added between the decorative paper and the substrate as a stress buffer layer.

4. The paper softening process according to claim 1, characterized in that, The specific parameters of the gradient hot pressing in step S108 are as follows: Closure period: Temperature 110-120℃, Pressure 1.5-2.0MPa; Curing period: Heat to 160-180℃ and pressurize to 3.0-3.5MPa; Setting period: Cooling and pressure maintenance.

5. The paper softening process according to claim 4, characterized in that, For deep embossed products, a brief vacuum pumping process is introduced during the closing period of step S108 to remove interlayer air.

6. The paper softening process according to claim 4, characterized in that, When dry flower / white spot defects occur, extend the low-pressure time of the closing period by 10-15 seconds or reduce the curing temperature by 5-10℃.

7. The paper softening process according to claim 1, characterized in that, In step S103, when applying the softener, a differentiated formula is set for different types of paper: a high-penetration softener formula is used for white / solid-color paper, and a high-viscosity softener formula is used for wood grain paper.

8. The paper softening process according to claim 1, characterized in that, The specific steps for establishing the dilution model in step S103 are as follows: calculate the dilution ratio of the softener based on the basis weight and fiber density of the base paper.

9. The paper softening process according to claim 1, characterized in that, The bottom nonwoven fabric used in step S106 is a highly breathable nonwoven fabric with a basis weight of 30-50 g / m².

10. The paper softening process according to claim 1, characterized in that, In step S102, when impregnating modified melamine resin and drying it, the resin solid content is controlled at 45-50% and the viscosity is controlled at 200-400 cps.

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