High-strength tensile fiber modified decorative paper and preparation process thereof

Abstract

The invention relates to the related technical field of fiber modified decorative paper, and discloses high-strength tensile fiber modified decorative paper and a preparation technology thereof.The high-strength tensile fiber modified decorative paper comprises a pretreatment module, a dipping module, a forming module and a post-treatment module; the pretreatment module comprises a temperature-adjustable soaking unit, a crushing unit and a conveying unit. Through the synergistic effect of nano-silica and epoxy resin in the composite modified liquid, a compact cross-linked network is formed on the surface of the fiber, the tensile strength of the decorative paper is improved, the purpose of optimizing the tensile strength is achieved, and through fiber length control and layered screening, the fiber distribution uniformity is improved, and the tensile strength of the decorative paper is improved. The durability of the decorative paper is improved through processes such as ultraviolet curing and the like, and the flame retardant property of the decorative paper is further guaranteed through a silica network structure formed by the nano silicon dioxide and the epoxy resin.

Description

Technical Field

[0001] The invention relates to the technical field related to fiber-modified decorative paper, in particular to a high-strength tensile fiber-modified decorative paper and a preparation process thereof. Background Art

[0002] Decorative paper is an indispensable raw material in many building materials products, such as low-pressure boards, high-pressure boards used in furniture and cabinets, as well as fireproof boards and floors.

[0003] Most of the existing decorative papers have problems such as low tensile strength and easy aging and cracking. For example, by using a single resin impregnation, there are defects such as uneven modification and insufficient interface bonding strength after hot pressing, which leads to insufficient overall strength of the decorative paper and affects its service life in the actual process. In order to solve such problems, a high-strength tensile fiber modified decorative paper and a preparation process thereof are proposed. Summary of the invention

[0004] The present invention provides a high-strength tensile fiber modified decorative paper and a preparation process thereof, which solves the problems in the above-mentioned background technology.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] A high-strength tensile fiber modified decorative paper and a preparation process thereof, comprising a pretreatment module, an impregnation module, a molding module, and a post-treatment module;

[0007] The pretreatment module includes a temperature-adjustable soaking unit, a crushing unit and a conveying unit. The soaking unit is used to degrease the plant fiber pulp with an alkaline solution at 60-80° C., and the crushing unit cuts the fiber to a length of 0.5-2 mm through a mechanical structure with adjustable blade spacing.

[0008] The impregnation module is connected to the pretreatment module through a pipeline, and includes an impregnation unit and a dispersion unit. The impregnation unit is provided with a composite modified liquid (containing 10-15wt% epoxy resin emulsion, 3-5wt% nano-silicon dioxide and 0.5-1wt% coupling agent KH-550). The frequency of the dispersion unit is set to 20-40kHz to achieve uniform combination of the fiber and the modified liquid.

[0009] The forming module includes a dehydration unit and a hot pressing unit. The dehydration unit sucks the fiber slurry to a moisture content of 40-50% by negative pressure. The temperature of the hot pressing roller group in the hot pressing unit is set to 150-180°C and the pressure is 5-8MPa.

[0010] The post-processing module includes a curing unit and a spraying unit. The ultraviolet curing wavelength range in the curing unit is 280-400nm. The surface coating in the spraying unit is a mixture of polyurethane resin and graphene in a mass ratio of 10:1.

[0011] Preferably, the soaking unit of the pretreatment module is provided with a multi-layer screen structure with a screen aperture of 100-200 meshes for synchronously separating fiber impurities.

[0012] Preferably, the working time of the dispersion unit is 10-20 minutes, and the power density is 0.5-1.0 W / cm 3 .

[0013] Preferably, the hot pressing roller group in the hot pressing unit realizes gradient pressurization through a segmented temperature control system, with an initial pressure of 3 MPa and a final pressure rising to 8 MPa.

[0014] A preparation process of high-strength tensile fiber modified decorative paper comprises the following steps:

[0015] S1: Soak the wood pulp fibers in an alkaline solution (pH 10-12) for 30-60 minutes, and crush them to obtain short fibers with a length of 0.5-2 mm;

[0016] S2: Immerse the short fibers in the composite modification liquid and disperse them under ultrasonic waves for 10-20 minutes;

[0017] S3: After dehydration, hot pressing is performed, and the hot pressing temperature is controlled at 150-180°C, the pressure is 5-8MPa, and the time is 2-5 minutes;

[0018] S4: Spraying polyurethane-graphene coating after UV curing, and rolling up after drying

[0019] Preferably, the solid content of the composite modified liquid in step S2 is 12-18%, and the viscosity is controlled at 200-500 mPa·s.

[0020] Preferably, the UV curing energy density in step S4 is 300-500 mJ / cm 2 , the coating thickness is 10-20μm.

[0021] Preferably, the wood pulp fiber is a pulp of coniferous wood and hardwood mixed in a mass ratio of 7:3.

[0022] The advantages and positive effects of the present invention are: through the synergistic effect of nano-silicon dioxide and epoxy resin in the composite modified liquid, a dense cross-linked network is formed on the fiber surface, so that the tensile strength of the decorative paper is improved, thereby achieving the purpose of optimizing the tensile strength, and after fiber length control and layered screening, the uniformity of fiber distribution is improved, thereby achieving the purpose of further enhancing its tear resistance, and the durability of the decorative paper is also improved through processes such as ultraviolet curing, and the flame retardant performance of the decorative paper is further guaranteed by the silicon-oxygen network structure formed by nano-silicon dioxide and epoxy resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 It is a schematic diagram of the process of the present invention;

[0025] The symbols in the accompanying drawings are described as follows:

[0026] 1. Pretreatment module; 11. Soaking unit; 12. Crushing unit; 13. Conveying unit;

[0027] 2. Impregnation module; 21. Impregnation unit; 22. Dispersion unit;

[0028] 3. Forming module; 31. Dehydration unit; 32. Hot pressing unit;

[0029] 4. Post-processing module; 41. Curing unit; 42. Spraying unit. DETAILED DESCRIPTION

[0030] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0031] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0032] Reference Figure 1 As shown, decorative paper is an indispensable raw material in many building materials products, such as low-pressure boards and high-pressure boards used in furniture and cabinets, as well as fireproof boards and floors. Most existing decorative papers have problems such as low tensile strength and easy aging and cracking. For example, by using a single resin for impregnation, there are defects such as uneven modification and insufficient interface bonding after hot pressing, which leads to insufficient overall strength of the decorative paper and affects its service life in the actual process. In order to solve such problems, a high-strength tensile fiber modified decorative paper and a preparation process thereof are proposed, including a pretreatment module 1, an impregnation module 2, a molding module 3, and a post-treatment module 4;

[0033] The pretreatment module 1 includes a temperature-adjustable soaking unit 11, a crushing unit 12 and a conveying unit 13. The soaking unit 11 is used to degrease the plant fiber pulp with an alkaline solution at 60-80° C., and the crushing unit 12 cuts the fiber to a length of 0.5-2 mm through a mechanical structure with adjustable blade spacing.

[0034] The impregnation module 2 is connected to the pretreatment module 1 through a pipeline, and includes an impregnation unit 21 and a dispersion unit 22. The impregnation unit 21 is provided with a composite modified liquid (containing 10-15wt% epoxy resin emulsion, 3-5wt% nano-silicon dioxide and 0.5-1wt% coupling agent KH-550). The frequency of the dispersion unit 22 is set to 20-40kHz to achieve uniform combination of the fiber and the modified liquid.

[0035] The forming module 3 includes a dehydration unit 31 and a hot pressing unit 32. The dehydration unit 31 sucks the fiber slurry to a moisture content of 40-50% by negative pressure. The temperature of the hot pressing roller group in the hot pressing unit 32 is set to 150-180°C and the pressure is 5-8MPa.

[0036] The post-processing module 4 includes a curing unit 41 and a spraying unit 42. The UV curing wavelength range in the curing unit 41 is 280-400nm. The surface coating in the spraying unit 42 is formed by mixing polyurethane resin and graphene in a mass ratio of 10:1. Through the synergistic effect of nano-silicon dioxide and epoxy resin in the composite modified liquid, a dense cross-linked network is formed on the fiber surface, so that the tensile strength of the decorative paper is improved, thereby achieving the purpose of optimizing the tensile strength. In addition, after fiber length control and layered screening, the uniformity of fiber distribution is improved, thereby achieving the purpose of further enhancing its tear resistance. The durability of the decorative paper is also improved through processes such as UV curing. The flame retardant performance of the decorative paper is further guaranteed by the silicon-oxygen network structure formed by nano-silicon dioxide and epoxy resin.

[0037] It should be noted that the fiber degreasing and crushing: take coniferous wood pulp (70wt%) and broadleaf wood pulp (30wt%) and mix them, put them into the soaking unit 11, add 5% NaOH solution (pH=11), heat to 65°C and treat at a constant temperature for 40 minutes, and the degreasing rate is ≥95% (only 80% in the traditional process). The soaking unit 11 is built with three layers of stainless steel screens (with apertures of 200 mesh, 150 mesh, and 100 mesh respectively), and the fibers pass through the screens in turn to remove lignin residues (the impurity content is reduced from the initial 8% to 0.5%); gradient filtration is achieved through multi-layer screens to avoid fiber clogging of the equipment, while improving the fiber purity and reducing the subsequent waste of modified liquid.

[0038] Furthermore, after the above degreasing, the fiber enters the fiber crushing stage. The degreasing fiber is sent to the crushing unit 12 through the conveying unit 13, and the blade spacing is adjusted to 0.3mm. The fiber length distribution after crushing is 0.8-1.5mm (accounting for 85%). The crusher blade adopts tungsten carbide coating, the rotation speed is 3000rpm, and it is equipped with an infrared sensor to monitor the fiber length in real time. The blade spacing is automatically adjusted when the limit is exceeded. The above-mentioned structure can achieve precise control of the fiber size, so that it can fully contact with the modified liquid in the subsequent impregnation, and the interface bonding strength is increased by 30%.

[0039] The conveying unit 13 includes a screw conveyor, and the crushing unit 12 includes a fiber crusher.

[0040] It should also be noted that the impregnation module 2 includes the preparation of the modified liquid, in which epoxy resin emulsion (12wt%), nano-silicon dioxide (4wt%, particle size 30nm), coupling agent KH-550 (0.8wt%) and water are mixed and stirred to a viscosity of 350mPa·s (25°C); and the ultrasonic impregnation process is completed, specifically: the broken fiber enters the impregnation unit 21 through the pneumatic valve, the liquid-to-solid ratio is controlled to 10:1, and the dispersion unit 22 is started, the frequency is 35kHz, and the power density is 0.8W / cm 3 , treated for 15 minutes, a spiral stirring paddle (rotation speed 50rpm) is set at the bottom of the impregnation unit 21, which works synergistically with ultrasound to ensure that the modified liquid penetrates into the fiber micropores; the nano-silica is evenly embedded in the fiber surface grooves through the ultrasonic cavitation effect (SEM observation shows that the coverage rate is ≥90%), and the tensile strength is increased to 52MPa; It should be noted that the above-mentioned dispersion unit 22 contains an ultrasonic dispersion device.

[0041] Furthermore, in the forming module 3, the impregnated fiber slurry is transported to the dehydration unit 31, and is sucked to a moisture content of 45% under a negative pressure of -0.08 MPa to form a continuous fiber mat; the fiber mat is then sent to the hot pressing unit 32 and controlled in two stages. The first stage: temperature 150°C, pressure 3MPa, time 1 minute, preliminary removal of bubbles; the second stage: temperature 170°C, pressure 8MPa, time 3 minutes, the epoxy resin is completely cured; gradient pressurization is used to avoid fiber breakage (breakage rate ≤0.1%), and at the same time the resin flows to fill the fiber gaps, and the porosity is <2% (traditional process ≥5%).

[0042] It is worth mentioning that the specific form of UV curing in the post-processing module 4 is: the hot pressed paper passes through the curing unit 41, with a wavelength of 365nm and an energy density of 400mJ / cm 2The irradiation time is 30 seconds, and the mixed liquid of polyurethane resin and graphene (mass ratio 10:1) is evenly coated by the spraying unit 42, the coating thickness is 15 μm, and the hot air drying at 60°C is carried out for 10 minutes to achieve the purpose of coating spraying. The above process can achieve the formation of a continuous conductive network (surface resistance ≤ 10 3 Ω), having both antistatic and electromagnetic shielding functions; it should be noted that the above-mentioned curing unit 41 includes a UV curing device, and the spraying unit 42 includes a high-pressure airless sprayer.

[0043] Additionally, the overall structure described above is listed as Example 1, and the following differences are obtained by comparing the proportions in the following table;

[0044]

[0045] Table 1

[0046] As the above processes are carried out in an orderly manner, a fiber-modified decorative paper with high strength and tensile strength can be obtained, and some structures are prior art and thus will not be described in detail.

[0047] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive, and therefore the present invention is not limited to the embodiments described in the specific implementation manners. Any other implementation manners derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A high-strength tensile fiber modified decorative paper and a preparation process thereof, characterized in that: It comprises a pre-treatment module (1), an impregnation module (2), a molding module (3), and a post-treatment module (4); The pretreatment module (1) comprises a temperature-adjustable soaking unit (11), a crushing unit (12) and a conveying unit (13); the soaking unit (11) is used to degrease the plant fiber pulp with an alkaline solution at 60-80° C., and the crushing unit (12) cuts the fibers to a length of 0.5-2 mm through a mechanical structure with adjustable blade spacing; The impregnation module (2) is connected to the pretreatment module (1) via a pipeline, and comprises an impregnation unit (21) and a dispersion unit (22); the impregnation unit (21) is provided with a composite modified liquid (containing 10-15wt% epoxy resin emulsion, 3-5wt% nano-silicon dioxide and 0.5-1wt% coupling agent KH-550); the frequency of the dispersion unit (22) is set to 20-40kHz, so as to achieve uniform combination of the fiber and the modified liquid; The forming module (3) comprises a dehydration unit (31) and a hot pressing unit (32); the dehydration unit (31) sucks the fiber slurry to a moisture content of 40-50% by negative pressure; the temperature of the hot pressing roller group in the hot pressing unit (32) is set to 150-180° C. and the pressure is set to 5-8 MPa; The post-processing module (4) comprises a curing unit (41) and a spraying unit (42); the ultraviolet curing wavelength range in the curing unit (41) is 280-400 nm; and the surface coating in the spraying unit (42) is formed by mixing polyurethane resin and graphene in a mass ratio of 10:

1.

2. The high-strength tensile fiber modified decorative paper and preparation process thereof according to claim 1, characterized in that: The soaking unit (11) of the pretreatment module (1) is provided with a multi-layer screen structure with a screen aperture of 100-200 meshes, which is used for synchronously separating fiber impurities.

3. The high-strength tensile fiber modified decorative paper and preparation process thereof according to claim 1, characterized in that: The working time of the dispersion unit (22) is 10-20 minutes, and the power density is 0.5-1.0 W / cm 3 .

4. The high-strength tensile fiber modified decorative paper and its preparation process according to claim 1, characterized in that: The hot pressing roller group in the hot pressing unit (32) realizes gradient pressurization through a segmented temperature control system, with the initial pressure being 3 MPa and the final pressure rising to 8 MPa.

5. A process for preparing high-strength tensile fiber modified decorative paper, characterized in that: The following steps are involved: S1: Soak the wood pulp fibers in an alkaline solution (pH 10-12) for 30-60 minutes, and crush them to obtain short fibers with a length of 0.5-2 mm; S2: Immerse the short fibers in the composite modification liquid and disperse them under ultrasonic waves for 10-20 minutes; S3: After dehydration, hot pressing is performed, and the hot pressing temperature is controlled at 150-180°C, the pressure is 5-8MPa, and the time is 2-5 minutes; S4: spraying polyurethane-graphene coating after UV curing and rolling up after drying.

6. The high-strength tensile fiber modified decorative paper and the preparation process thereof according to claim 5, characterized in that: The solid content of the composite modified liquid in step S2 is 12-18%, and the viscosity is controlled at 200-500 mPa·s.

7. The high-strength tensile fiber modified decorative paper and its preparation process according to claim 5, characterized in that: The UV curing energy density in step S4 is 300-500 mJ / cm 2 , the coating thickness is 10-20μm.

8. The high-strength tensile fiber modified decorative paper and its preparation process according to claim 5, characterized in that: The wood pulp fiber is a pulp of coniferous wood and hardwood mixed in a mass ratio of 7:3.

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