A layer-assembled flexible fiberboard and preparation method thereof

Abstract

The present invention provides a method for preparing a layer-assembled flexible fiberboard, comprising the following steps: pressing and molding plant fibers to obtain a two-dimensional ultra-thin fiber grid; the plant fibers are arranged in parallel, and the angle with the horizontal plane is not higher than 30°; the thermoplastic resin film, the two-dimensional ultra-thin fiber grid and paper are alternately stacked, and then hot-pressed to obtain a layer-assembled flexible fiberboard. In the present invention, the plant fibers are arranged in parallel, and the angle with the horizontal plane is not higher than 30°, which can make the plant fibers oriented, and then the plant fibers are pressed into a two-dimensional ultra-thin fiber grid, and then alternately stacked with the resin film and paper, and the interaction of the three-dimensional network is eliminated by introducing the strategy of "layer assembly", and the flexible design is initially realized; then, hot pressing is used to make the thermoplastic resin melt and penetrate into the grid and the surface layer of the paper, so as to achieve shallow network penetration and improve the flexibility of the board.

Description

Technical Field

[0001] The invention belongs to the technical field of flexible artificial boards, and in particular relates to a layer-assembled flexible fiberboard and a preparation method thereof. Background Art

[0002] As an innovative product in the fiberboard industry, ultra-thin fiberboard is widely used in decorative boards, electronic circuit boards, box boards, container boards, door skins, musical instruments, vehicles, ships, and medical equipment due to its thin thickness and light weight, effectively expanding and extending the uses and fields of medium and high density fiberboards. Ultra-thin fiber thickness is very thin, about 1.00mm, and the ultra-thin thickness gives fiberboard advantages such as bendability and veneerability. It can be used to replace wood veneer as a veneer material for plywood to avoid the problem of plywood surface cracking caused by anisotropy of wood veneer, and can be directly used for decorative veneer of curved walls or curved panels, greatly expanding the application field of ultra-thin fiberboard and increasing its added value. Although ultra-thin fiberboard has the advantages of being bendable and can be veneered on curved surfaces, ultra-thin fiberboard is currently prepared using adhesives such as urea-formaldehyde resin, phenolic resin or melamine-modified resin, isocyanate, etc., which have the following defects: this type of adhesive is a thermosetting resin, and after curing, the fiberboard product is very rigid and cannot give the fiberboard super flexibility, which means that this type of product cannot be used in fields such as large curved surfaces, limiting the application range of the product. Therefore, how to improve the flexibility of fiberboard so that it can be used in large curved surfaces and large curved areas has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0003] The purpose of the present invention is to provide a layer-assembled flexible fiberboard and a preparation method thereof. The layer-assembled flexible fiberboard prepared by the preparation method provided by the present invention has good flexibility, breaking through the limitations of the use of fiberboard flat panels, and also breaking through the inability of ultra-thin fiberboard to be used in large curved surfaces and large arc bending fields, which is of great significance to further promote the transformation and upgrading of the fiberboard industry.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a layer-assembled flexible fiberboard, comprising the following steps:

[0006] (1) pressing plant fibers to obtain a two-dimensional ultra-thin fiber grid; the plant fibers are arranged in parallel and the angle between the plant fibers and the horizontal plane is not higher than 30°;

[0007] (2) The thermoplastic resin film, the two-dimensional ultra-thin fiber grid obtained in step (1) and paper are alternately stacked and then hot-pressed to obtain a layer-assembled flexible fiberboard.

[0008] Preferably, the plant fiber in step (1) is at least one of wood fiber, bamboo fiber and hemp fiber.

[0009] Preferably, in step (1), the length of the plant fiber is 0.5 to 3.5 mm, and the linear density of the plant fiber is 1.5 to 15 dtex.

[0010] Preferably, in step (1), the pressing pressure is 0.1-2 MPa, the pressing time is 1-100 s, and the pressing temperature is 20-100°C.

[0011] Preferably, the thickness of the two-dimensional ultra-thin fiber grid in step (1) is ≤150 μm.

[0012] Preferably, the thickness of the thermoplastic resin film in step (2) is 0.01 to 500 μm.

[0013] Preferably, the thermoplastic resin film in step (2) is at least one of a polyethylene film, a polypropylene film, a polyurethane film, a polyamide film, an ethylene-vinyl acetate polymer film and a vinyl acetate polymer film.

[0014] Preferably, in step (2), the number of layers of the two-dimensional ultra-thin fiber grid is 1 to 50, the number of layers of the paper is 1 to 50, and the number of layers of the thermoplastic resin film is one more than the total number of layers of the two-dimensional ultra-thin fiber grid and the paper.

[0015] Preferably, in step (2), the temperature of the hot pressing molding is 100-200° C., the pressure of the hot pressing molding is 0.01-1 MPa, and the time of the hot pressing molding is 0.01-3 min.

[0016] The present invention also provides a layer-assembled flexible fiberboard prepared by the preparation method described in the above technical solution.

[0017] The present invention provides a method for preparing a layer-assembled flexible fiberboard, comprising the following steps: pressing and molding plant fibers to obtain a two-dimensional ultra-thin fiber grid; the plant fibers are arranged in parallel, and the angle with the horizontal plane is not higher than 30°; the thermoplastic resin film, the two-dimensional ultra-thin fiber grid and the paper are alternately stacked, and then hot-pressed to obtain a layer-assembled flexible fiberboard. In the present invention, the plant fibers are arranged in parallel, and the angle with the horizontal plane is not higher than 30°, which can make the plant fibers arranged in a directional manner, and then the plant fibers are pressed into a two-dimensional ultra-thin fiber grid, and then alternately stacked with the resin film and the paper, and the interaction of the three-dimensional network is eliminated by introducing the strategy of "layer assembly", and the flexible design is preliminarily realized; then, hot pressing is used to melt the thermoplastic resin and penetrate into the grid and the surface layer of the paper to achieve shallow network penetration, which can improve the interlayer bonding force to avoid interlayer cracking of the board on the one hand, and on the other hand, since there is no resin restraint inside the grid, it can also give the fibers the ability to slide, further improving the flexibility of the board. Experimental results show that the bending radius of the flexible fiberboard prepared by the present invention is ≤35mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a bending diagram of the fiberboard prepared in Example 1;

[0019] Figure 2 This is a bending diagram of the fiberboard prepared in Example 4;

[0020] Figure 3 This is a bending diagram of the fiberboard prepared in Comparative Example 1;

[0021] Figure 4 This is a bending diagram of the fiberboard prepared in Comparative Example 2. DETAILED DESCRIPTION

[0022] The present invention provides a method for preparing a layer-assembled flexible fiberboard, comprising the following steps:

[0023] (1) pressing plant fibers to obtain a two-dimensional ultra-thin fiber grid; the plant fibers are arranged in parallel and the angle between the plant fibers and the horizontal plane is not higher than 30°;

[0024] (2) The thermoplastic resin film, the two-dimensional ultra-thin fiber grid obtained in step (1) and paper are alternately stacked and then hot-pressed to obtain a layer-assembled flexible fiberboard.

[0025] Unless otherwise specified in the present invention, all raw materials used in the present invention are commercially available products in the art.

[0026] The present invention compresses plant fibers into shapes to obtain a two-dimensional ultra-thin fiber grid.

[0027] In the present invention, the plant fiber is preferably at least one of wood fiber, bamboo fiber and hemp fiber; the length of the plant fiber is preferably 0.5-3.5 mm, more preferably 0.5-2 mm, more preferably 0.5-1.5 mm; the linear density of the plant fiber is preferably 1.5-15 dtex, more preferably 1.5-10 dtex, more preferably 1.5-5 dtex.

[0028] In the present invention, the plant fibers are preferably softened and cleaned before use. The present invention can further improve the flexibility of the board by pre-softening the plant fibers.

[0029] In the present invention, the softening treatment is preferably performed by soaking the plant fiber in an alkaline solution.

[0030] In the present invention, the solute of the alkaline solution is preferably at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide; the solvent of the alkaline solution is preferably water; the mass concentration of the alkaline solution is preferably 5-10%, more preferably 8%. The present invention has no special limitation on the amount of the alkaline solution, as long as the plant fiber is completely immersed.

[0031] In the present invention, the soaking time is preferably 1 to 5 hours, more preferably 2 to 4 hours; the soaking temperature is preferably 30 to 80°C, more preferably 40 to 60°C.

[0032] The present invention has no particular limitation on the cleaning operation, and any operation well known to those skilled in the art may be used.

[0033] In the present invention, the plant fibers are arranged in parallel and the angle between them and the horizontal plane is not higher than 30°, preferably the angle between them and the horizontal plane is not higher than 15°, more preferably not higher than 10°. In the present invention, the arrangement that the plant fibers are arranged in parallel and the angle between them and the horizontal plane is not higher than 30° can make the plant fibers arranged in a directional manner, which is beneficial to improving the flexibility of the board.

[0034] In the present invention, it is preferred to use air-laying, manual screen-laying technology, or salvage, papermaking, or net-pulling technology after floating the plant fibers in water so that the plant fibers are arranged in parallel, and the angle with the horizontal plane is not higher than 30°. The present invention has no special limitation on the above-mentioned operations, and the operations well known to those skilled in the art are used, and the plant fibers are arranged in parallel, and the angle with the horizontal plane is not higher than 30°.

[0035] In the present invention, the pressure of the press molding is preferably 0.1-2MPa, more preferably 0.5-1.5MPa, and more preferably 0.8-1.2MPa; the time of the press molding is preferably 1-100s, more preferably 5-50s, and more preferably 10-30s; the temperature of the press molding is preferably 20-100°C, more preferably 30-80°C, and more preferably 50-60°C; the press molding is preferably carried out in a press. The present invention does not specifically limit the model of the press, and instruments and equipment familiar to those skilled in the art can be used. The present invention can further improve the flexibility of the sheet by controlling the process parameters of the press molding.

[0036] After the compression molding is completed, the present invention preferably dries the product obtained by the compression molding to obtain a two-dimensional ultra-thin fiber grid.

[0037] In the present invention, the drying temperature is preferably 20 to 100° C. The present invention has no particular limitation on the drying time, and the drying time may be until constant weight.

[0038] In the present invention, the thickness of the two-dimensional ultra-thin fiber grid is preferably ≤150 μm, more preferably 60-100 μm, and more preferably 80 μm. The present invention can further improve the flexibility of the fiberboard by controlling the thickness of the two-dimensional ultra-thin fiber grid.

[0039] After obtaining the two-dimensional ultra-thin fiber grid, the present invention alternately stacks the thermoplastic resin film, the two-dimensional ultra-thin fiber grid and paper, and then performs hot pressing to obtain a layer-assembled flexible fiberboard.

[0040] In the present invention, the thermoplastic resin film is preferably at least one of a polyethylene film, a polypropylene film, a polyurethane film, a polyamide film, an ethylene-vinyl acetate polymer film and a vinyl acetate polymer film. In the present invention, the thermoplastic resin film is an adhesive.

[0041] In the present invention, the method for preparing the ethylene-vinyl acetate polymer film is preferably to spread the ethylene-polyvinyl acetate emulsion on a flat surface and then dry it; the drying temperature is preferably 50-100°C.

[0042] In the present invention, the method for preparing the vinyl acetate polymer film is preferably to spread polyvinyl acetate emulsion (ie white latex) on a flat surface and then dry it; the drying temperature is preferably 50-100°C.

[0043] In the present invention, the thickness of the thermoplastic resin film is preferably 0.01 to 500 μm, more preferably 0.05 to 200 μm, and even more preferably 0.1 to 100 μm.

[0044] In the present invention, the thickness of the paper is preferably 0.01-200 μm; the paper is preferably relief paper, newsprint, offset paper, coated paper, illustrated paper, writing paper, embossed paper, dictionary paper, writing paper, white paper or kraft paper, more preferably writing paper, writing paper or kraft paper. In the present invention, the surface density of the paper is greater than that of the two-dimensional ultra-thin fiber grid, which is more conducive to improving the mechanical properties of the flexible fiberboard and achieving a combination of board strength and flexibility.

[0045] The present invention has no special limitation on the operation of alternately stacking the thermoplastic resin film, the two-dimensional ultra-thin fiber grid and the paper, as long as the thermoplastic resin film, the two-dimensional ultra-thin fiber grid and the paper are arranged in sequence.

[0046] In the present invention, the number of layers of the two-dimensional ultra-thin fiber grid is preferably 1 to 50 layers, more preferably 4 to 40 layers, and more preferably 5 to 10 layers; the number of layers of the paper is preferably 1 to 50 layers, more preferably 4 to 40 layers, and more preferably 5 to 10 layers; the number of layers of the thermoplastic resin film is preferably one more layer than the total number of layers of the two-dimensional ultra-thin fiber grid and the paper; the number of layers of the two-dimensional ultra-thin fiber grid is preferably the same as the number of layers of the paper. The present invention can make the upper and lower surfaces of the blank obtained by alternately stacking the thermoplastic resin film, the two-dimensional ultra-thin fiber grid and the paper be thermoplastic resin films, so that the two-dimensional ultra-thin fiber grid and the paper can be fully bonded, and the film itself can also be used to make the grid and the paper have the ability to pull each other, thereby improving the flexibility of the board.

[0047] In the present invention, the two-dimensional ultra-thin fiber grid preferably accounts for 30-99% of the mass of the slab obtained by alternately stacking the thermoplastic resin film, the two-dimensional ultra-thin fiber grid and the paper, more preferably 50-80%, and more preferably 60-70%. The present invention can increase the proportion of degradable components by controlling the above parameters, promote the green development of flexible fiberboard, and help achieve the dual carbon goals.

[0048] In the present invention, the temperature of the hot pressing molding is preferably 100-200°C, more preferably 130-180°C, and more preferably 150-170°C; the pressure of the hot pressing molding is preferably 0.01-1MPa, more preferably 0.1-0.5MPa, and more preferably 0.2-0.3MPa; the time of the hot pressing molding is preferably 0.01-3min, more preferably 2-3min, and more preferably 2.5min. The present invention adopts a high temperature and low pressure method to make the thermoplastic resin melt and penetrate into the grid and the surface layer of the paper, and realize shallow network penetration (the thermoplastic resin melts and diffuses slightly under high temperature and low pressure, and shallowly penetrates into the ultra-thin fiber grid, producing a mechanical interlocking effect on the grid surface, thereby achieving a bonding effect); the flexibility of the fiberboard can be further improved by controlling the process parameters of the hot pressing molding.

[0049] In the present invention, the hot pressing molding is preferably carried out in a press. The present invention has no particular limitation on the type of the press, and any equipment well known to those skilled in the art can be used.

[0050] After the hot pressing forming is completed, the present invention preferably cools the product obtained by the hot pressing forming to obtain a layer-assembled flexible fiberboard.

[0051] The present invention has no particular limitation on the cooling operation, and cooling to below 50° C. is sufficient.

[0052] In the present invention, the thickness of the flexible fiberboard assembled by the layers is preferably ≤5 mm, more preferably 1 to 3 mm, and even more preferably 2 mm.

[0053] The present invention adopts a "layer assembly" strategy to achieve the flexibility of the fiberboard. A two-dimensional ultra-thin fiber grid and a thermoplastic resin film are assembled and hot-pressed to prepare a flexible fiberboard, eliminating the mutual pulling between fibers in the traditional three-dimensional network that causes the board to be too rigid, thereby giving the fiberboard flexibility.

[0054] The present invention proposes a high temperature and low pressure method to achieve "shallow network penetration". This method can not only improve the interlayer adhesion and avoid cracking of the board layers, but also give the fibers the ability to slide due to the lack of resin constraints inside the grid, further improving the flexibility of the board.

[0055] The present invention solves the problem of fiberboard homogenization, breaks through the limitations of the use of fiberboard flat panels, and also breaks through the inability of ultra-thin fiberboard to be used in large curved surfaces and large arc bending fields. It is of great significance to further promote the transformation and upgrading of the fiberboard industry.

[0056] The present invention also provides a layer-assembled flexible fiberboard prepared by the preparation method described in the above technical solution.

[0057] The layer-assembled flexible fiberboard provided by the present invention has excellent flexibility.

[0058] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] Example 1

[0060] The preparation method of the layer-assembled flexible fiberboard is as follows:

[0061] (1) Soaking poplar fibers in a sodium hydroxide solution with a temperature of 50° C. and a mass fraction of 5% for 1 hour, then cleaning the poplar fibers, and then breaking up the poplar fibers in water to make them uniformly suspended, fishing out the fibers by a metal mesh papermaking method, and then pressing them in a press, and then drying them at 50° C. to obtain a two-dimensional ultra-thin fiber grid with a thickness of 80 μm; wherein the length of the poplar fibers is 0.5 to 2.5 mm, and the linear density is 1.5 to 12 dtex; the poplar fibers are arranged in parallel and the angle with the horizontal plane is 30°; the pressing pressure is 2 MPa, the time is 60 s, and the temperature is 100° C.;

[0062] (2) A polyethylene film with a thickness of 0.05 mm, the two-dimensional ultra-thin fiber grid obtained in the step (1), and a writing A4 paper with a thickness of 80 μm are alternately stacked, and then placed in a hot press, and hot-pressed for 2 minutes at 130° C. and a pressure of 0.5 MPa, to obtain a layered flexible fiberboard with a thickness of 1 mm after cooling; wherein the number of layers of the writing A4 paper and the two-dimensional ultra-thin fiber grid are both 5 layers, and the number of layers of the polyethylene film is 11 layers; the two-dimensional ultra-thin fiber grid accounts for 80% of the mass of the slab obtained by alternately stacking the polyethylene film, the two-dimensional ultra-thin fiber grid, and the writing A4 paper.

[0063] Example 2

[0064] The preparation method of the layer-assembled flexible fiberboard is as follows:

[0065] (1) Soaking poplar fibers in a sodium hydroxide solution with a temperature of 80°C and a mass fraction of 8% for 2 hours, then cleaning the poplar fibers, laying the poplar fibers through a manual screen, and then pressing and forming them in a press, and then drying them at 50°C to obtain a two-dimensional ultra-thin fiber grid with a thickness of 120 μm; wherein the length of the poplar fibers is 0.5 to 2.5 mm, and the linear density is 1.5 to 12 dtex; the poplar fibers are arranged in parallel and the angle with the horizontal plane is 20°; the pressing pressure is 1.5 MPa, the time is 40 s, and the temperature is 80°C;

[0066] (2) A polypropylene film with a thickness of 0.05 mm, the two-dimensional ultra-thin fiber grid obtained in the step (1), and a kraft paper with a thickness of 100 μm are alternately stacked, and then placed in a hot press, and hot-pressed for 2 minutes at 170° C. and a pressure of 0.5 MPa, and after cooling, a layered flexible fiberboard with a thickness of 1 mm is obtained; wherein the number of layers of kraft paper and the two-dimensional ultra-thin fiber grid are both 4 layers, and the number of layers of the polypropylene film is 9 layers; the two-dimensional ultra-thin fiber grid accounts for 60% of the mass of the slab obtained by alternately stacking the polypropylene film, the two-dimensional ultra-thin fiber grid and the kraft paper.

[0067] Example 3

[0068] The preparation method of the layer-assembled flexible fiberboard is as follows:

[0069] (1) The eucalyptus fiber is soaked in a sodium hydroxide solution with a mass fraction of 5% at a temperature of 50°C for 1 hour, and then the eucalyptus fiber is cleaned and then put into water to be dispersed to make it in a uniform suspension state, and the fiber is salvaged by a metal mesh papermaking method, and then pressed in a press, and then dried at 70°C to obtain a two-dimensional ultra-thin fiber grid with a thickness of 60 μm; wherein the length of the eucalyptus fiber is 1.0-3.0 mm, and the linear density is 2.5-15 dtex; the eucalyptus fiber is arranged in parallel and the angle with the horizontal plane is 20°; the pressing pressure is 1 MPa, the time is 30 s, and the temperature is 50°C;

[0070] (2) A polyethylene film with a thickness of 0.05 mm, the two-dimensional ultra-thin fiber grid obtained in the step (1), and a newsprint with a thickness of 35 μm are alternately stacked, and then placed in a hot press, and hot-pressed for 3 minutes at 130° C. and a pressure of 0.2 MPa, to obtain a layered flexible fiberboard with a thickness of 2 mm after cooling; wherein the number of layers of newsprint and the two-dimensional ultra-thin fiber grid are both 10 layers, and the number of layers of the polyethylene film is 21 layers; the two-dimensional ultra-thin fiber grid accounts for 75% of the mass of the slab obtained by alternately stacking the polyethylene film, the two-dimensional ultra-thin fiber grid, and the newsprint.

[0071] Example 4

[0072] The preparation method of the layer-assembled flexible fiberboard is as follows:

[0073] (1) The bamboo fiber is soaked in a sodium hydroxide solution with a mass fraction of 10% at a temperature of 60°C for 1 hour, and then the bamboo fiber is cleaned, and then the bamboo fiber is laid through a manual screen, and then pressed in a press, and then dried at 80°C to obtain a two-dimensional ultra-thin fiber grid with a thickness of 150 μm; wherein the length of the bamboo fiber is 0.5-2.5 mm, and the linear density is 1.5-12 dtex; the bamboo fibers are arranged in parallel, and the angle with the horizontal plane is 10°; the pressing pressure is 0.5 MPa, the time is 100 s, and the temperature is 30°C;

[0074] (2) A polyurethane film with a thickness of 0.05 mm, the two-dimensional ultra-thin fiber grid obtained in the step (1), and a written A4 paper with a thickness of 30 μm are alternately stacked, and then placed in a hot press, and hot-pressed for 2.5 minutes at 150° C. and a pressure of 0.5 MPa, to obtain a layered flexible fiberboard with a thickness of 3 mm after cooling; wherein the number of layers of the written A4 paper and the two-dimensional ultra-thin fiber grid are both 40 layers, and the number of layers of the polyurethane film is 81 layers; the two-dimensional ultra-thin fiber grid accounts for 45% of the mass of the slab obtained by alternately stacking the polyurethane film, the two-dimensional ultra-thin fiber grid, and the written A4 paper.

[0075] Comparative Example 1

[0076] A4 paper and polyethylene film sold on the market were selected as raw materials. The thickness of the A4 paper was 100 μm. The A4 paper and the polyethylene film with a thickness of 0.1 mm were alternately stacked and placed in a hot press. The paper was hot-pressed at 130°C and a pressure of 0.2 MPa for 2 minutes. After cooling, a fiberboard with a thickness of 2 mm was obtained. The number of A4 paper layers was 30 and the number of polyethylene film layers was 31.

[0077] The fiberboard prepared in Comparative Example 1 is very rigid, difficult to bend, and has a large bending radius.

[0078] Comparative Example 2

[0079] Commercially available kraft paper and polyurethane film were selected as raw materials. The thickness of the kraft paper was 125 μm. The kraft paper was then alternately layered with a polyurethane film with a thickness of 0.2 mm. The paper was then placed in a hot press and hot-pressed at 150°C and a pressure of 0.2 MPa for 2 minutes. After cooling, a fiberboard with a thickness of 1 mm was obtained. The number of layers of kraft paper was 10, and the number of layers of polyurethane film was 11.

[0080] The fiberboard prepared in Comparative Example 1 is very rigid, difficult to bend, and has a large bending radius.

[0081] The bending drawings of the fiberboards prepared in Examples 1, 4 and Comparative Examples 1 and 2 are shown in FIG. Figures 1 to 4 shown.

[0082] In order to demonstrate the beneficial effects of the present invention, the fiberboards obtained from the above embodiments and comparative examples were subjected to a performance test of bending radius. The bending radius test was measured using a vernier caliper. The test results are shown in Table 1.

[0083] Table 1 Bending radius and thickness data of fiberboard of Examples 1 to 4 and Comparative Examples 1 to 2

[0084] Example Bending radius(mm) Plate thickness (mm) 1 25 1 2 25 1 3 35 2 4 20 3 Comparative Example 1 85 2 Comparative Example 2 55 1

[0085] From Table 1 and Figure 1 It can be seen that the fiberboard prepared by the present invention has an extremely low bending radius, which shows that the board has good flexibility and can give the fiberboard high added value.

[0086] It can be seen from the above embodiments and comparative examples that the layer-assembled flexible fiberboard prepared by the preparation method provided by the present invention has good flexibility, breaking through the limitations of the use of fiberboard flat panels and the inability of ultra-thin fiberboard to be used in large curved surfaces and large arcs, which is of great significance for further promoting the transformation and upgrading of the fiberboard industry.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a layer-assembled flexible fiberboard, comprising the following steps: (1) pressing plant fibers to obtain a two-dimensional ultra-thin fiber grid; the plant fibers are arranged in parallel and the angle between the plant fibers and the horizontal plane is not higher than 30°; (2) alternately stacking a thermoplastic resin film, the two-dimensional ultra-thin fiber grid obtained in step (1), and paper, and then performing hot pressing to obtain a layer-assembled flexible fiberboard; The thickness of the two-dimensional ultra-thin fiber grid in step (1) is ≤150 μm; In the step (2), the thermoplastic resin film is at least one of a polyethylene film, a polypropylene film, a polyurethane film, a polyamide film, an ethylene-vinyl acetate polymer film and a vinyl acetate polymer film; In step (2), the temperature of the hot pressing molding is 100-200° C., the pressure of the hot pressing molding is 0.01-1 MPa, and the time of the hot pressing molding is 0.01-3 min; By using heat pressing, the thermoplastic resin is melted and infiltrated into the mesh and the surface layer of the paper, achieving shallow network penetration, without the restraint of resin inside the mesh.

2. The preparation method according to claim 1, characterized in that: In the step (1), the plant fiber is at least one of wood fiber, bamboo fiber and hemp fiber.

3. The preparation method according to claim 1 or 2, characterized in that: In the step (1), the length of the plant fiber is 0.5-3.5 mm, and the linear density of the plant fiber is 1.5-15 dtex.

4. The preparation method according to claim 1, characterized in that: In the step (1), the pressure of the pressing molding is 0.1-2 MPa, the time of the pressing molding is 1-100 s, and the temperature of the pressing molding is 20-100° C.

5. The preparation method according to claim 1, characterized in that: The thickness of the thermoplastic resin film in step (2) is 0.01-500 μm.

6. The preparation method according to claim 1, characterized in that: In the step (2), the number of layers of the two-dimensional ultra-thin fiber grid is 1 to 50, the number of layers of the paper is 1 to 50, and the number of layers of the thermoplastic resin film is one more than the total number of layers of the two-dimensional ultra-thin fiber grid and the paper.

7. A layer-assembled flexible fiberboard prepared by the preparation method according to any one of claims 1 to 6.

Images