Plant fiber embedded steel bar composite board as well as preparation method and application thereof

Abstract

The invention provides a plant fiber embedded steel bar composite board as well as a preparation method and application thereof, and belongs to the technical field of plant fiber reinforced composite materials. The plant fiber embedded steel bar composite board comprises a composite board body and an embedded steel bar structure arranged on the surface or inside the composite board body. The composite board comprises a resin matrix and plant fibers dispersed in the resin matrix. According to the composite board, the embedded steel bar structure and the board are tightly connected and can jointly resist external force, and the mechanical property and the size stability of the composite board are effectively improved; and the composite board has electromagnetic shielding and heat-conducting properties. The result of the embodiment shows that the bending strength of the plant fiber embedded steel bar composite board provided by the invention can reach 10-15 MPa, the bending modulus can reach 700-3000 MPa, the impact strength can reach 8-10 KJ.m <-2 >, and the 24-hour water absorption thickness swelling rate is as low as 0.1-1.5%.

Description

Technical Field

[0001] The present invention relates to the technical field of plant fiber reinforced composite materials, and in particular to a plant fiber reinforced composite plate and a preparation method and application thereof. Background Art

[0002] Among traditional wood-plastic composite boards, plant fiber reinforced composite boards have a place in the material field due to their lightweight characteristics. However, plant fiber reinforced composite boards are obviously insufficient in strength and toughness. When subjected to large external forces, such boards are very prone to deformation, and in severe cases, they may even break. In addition, plant fibers have the characteristics of shrinking when dry and swelling when wet, and expanding when hot and contracting when cold, which makes plant fiber reinforced composite boards prone to dimensional deformation under different environmental (humidity, temperature) conditions.

[0003] At present, in order to improve the mechanical properties of plant fiber reinforced composite boards, the method of increasing the amount of adhesive is often used to improve the bonding strength between plant fibers and other components in the composite boards. However, excessive addition of adhesive will not only lead to a significant increase in the weight of the board, but also a significant increase in the harmful gases released by the adhesive, seriously polluting the environment and human health.

[0004] Therefore, there is an urgent need to provide a plant fiber reinforced composite plate with excellent mechanical properties and environmental protection. Summary of the invention

[0005] The object of the present invention is to provide a plant fiber reinforced composite board and a preparation method and application thereof. The plant fiber reinforced composite board provided by the present invention is environmentally friendly and has excellent mechanical properties and dimensional stability.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a plant fiber rebar-embedded composite board, comprising a composite board and a rebar-embedded structure arranged on the surface or inside of the composite board; the composite board comprises a resin matrix and plant fibers dispersed in the resin matrix.

[0008] Preferably, the mass ratio of the composite board to the anchor structure is 1:(0.05-0.2).

[0009] Preferably, the number of layers of the anchor structure is more than one.

[0010] Preferably, each layer of the embedded reinforcement structure is independently a grid structure in which reinforcement bars are arranged in a staggered manner, or a structure in which reinforcement bars of different thicknesses are intertwined and arranged in parallel.

[0011] Preferably, in terms of mass percentage, the reinforcing ribs include 60-100% of main reinforcing ribs and 0-40% of compound reinforcing ribs.

[0012] Preferably, the main reinforcing ribs are bamboo strips, plant fiber yarns or plant fiber prepreg tapes; and the composite reinforcing ribs are metal wires, glass fibers, carbon fibers or basalt fibers.

[0013] Preferably, in terms of mass percentage, the composite board comprises 5-85% of plant fibers and 15-95% of matrix.

[0014] Preferably, the plant fiber is one or more of bamboo fiber, hemp fiber, crop straw, cotton fiber, bagasse fiber, palm fiber, coconut shell fiber and banana fiber; and the matrix is ​​resin fiber or resin.

[0015] The present invention also provides a method for preparing the plant fiber reinforced composite board described in the above technical solution, comprising:

[0016] The plant fiber reinforced resin composite board is obtained by embedding or semi-embedding the reinforcing bar structure layer into the plant fiber reinforced resin composite felt material for compression molding;

[0017] Alternatively, the plant fiber reinforced resin composite board is assembled and then pressed to obtain the plant fiber reinforced resin composite board.

[0018] The present invention also provides the application of the plant fiber embedded steel bar composite board described in the above technical scheme or the plant fiber embedded steel bar composite board prepared by the preparation method described in the above technical scheme in transportation, low-altitude economy, building decoration, furniture manufacturing and packaging.

[0019] The present invention provides a plant fiber reinforced composite board, comprising a composite board and a reinforced bar structure arranged on the surface or inside of the composite board; the composite board comprises a resin matrix and plant fibers dispersed in the resin matrix. In the plant fiber reinforced composite board provided by the present invention, the reinforced bar structure is tightly connected to the composite board. When the plant fiber reinforced composite board is subjected to external force, the stress can be transferred from the composite board to the reinforced bar structure, so that the reinforced bar structure and the composite board are subjected to force together. At the same time, the reinforced bar structure itself has high strength, which effectively improves the ability of the plant fiber reinforced composite board to bear external force, and effectively improves the strength of the plant fiber reinforced composite board; the reinforced bar structure itself has excellent ductility, and can undergo large plastic deformation without breaking during the stress process, and can effectively absorb and dissipate energy, thereby improving the toughness of the plant fiber reinforced composite board; at the same time, the reinforced bar structure forms a stable skeleton structure on the composite board, which limits the deformation of the board, so that the board is not prone to excessive expansion or contraction deformation, and effectively improves the dimensional stability of the plant fiber reinforced composite board. The results of the examples show that the bending strength of the plant fiber embedded steel bar composite board provided by the present invention can reach 10-15MPa, the bending modulus can reach 700-3000MPa, and the impact strength can reach 8-10KJ·m -2The 24h water absorption thickness expansion rate is as low as 0.1-1.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the assembly of the composite board and the embedded steel bar structure in the plant fiber embedded steel bar composite board of Example 2;

[0021] Figure 2 This is a physical picture of the plant fiber reinforced composite board of Example 2;

[0022] Figure 3 This is a physical picture of the plant fiber reinforced composite board of Example 2;

[0023] Figure 4 is a front view of the composite reinforcing rib in Example 3;

[0024] Figure 5 This is an end view of the composite reinforcement rib in Example 3. DETAILED DESCRIPTION

[0025] The present invention provides a plant fiber rebar-embedded composite board, comprising a composite board and a rebar-embedded structure arranged on the surface or inside of the composite board; the composite board comprises a resin matrix and plant fibers dispersed in the resin matrix.

[0026] The plant fiber embedded steel bar composite board provided by the present invention comprises a composite board, and the composite board comprises a resin matrix and plant fibers dispersed in the resin matrix.

[0027] As an embodiment of the present invention, the plant fiber in the composite board can be 5-85%, 15-70%, or 30-50% by mass; the resin matrix in the composite board can be 15-95%, 30-85%, or 50-70%. In the present invention, by limiting the amount of plant fiber and resin matrix, the relationship between the strength and toughness of the composite board is effectively balanced, and the mechanical properties of the composite board are further improved.

[0028] As an embodiment of the present invention, the plant fiber can be one or more of bamboo fiber, hemp fiber, crop straw, cotton fiber, bagasse fiber, palm fiber, coconut shell fiber and banana fiber. In an embodiment of the present invention, the plant fiber can be specifically wheat straw or rice straw. In the present invention, the board is prepared using plant fiber, so that the obtained board is environmentally friendly; the type of plant fiber is limited, and low-cost fiber or waste plant fiber is used as raw material to reduce the cost of the board.

[0029] As an embodiment of the present invention, the resin matrix can be resin fiber or resin; the resin fiber can be polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, polylactic acid fiber, polyethylene terephthalate fiber, polycarbonate fiber or polyvinyl chloride fiber; the resin can be a thermoplastic resin and / or a thermosetting resin; the thermoplastic resin can be one or more of polypropylene, polyethylene, polyvinyl chloride, polylactic acid, polyamide, bio-based polyamide, polycarbonate, polybutylene adipate / terephthalate, polyethylene terephthalate or polyester; the thermosetting resin can be one or more of epoxy resin, vinyl epoxy resin, phenolic resin, unsaturated polyester resin, silicone resin or furan resin. In the present invention, by limiting the type of resin matrix, the bonding between plant fiber and resin matrix is ​​ensured, and the mechanical properties of the composite board are further improved.

[0030] The plant fiber embedded steel bar composite board provided by the present invention further comprises an embedded steel bar structure arranged on the surface or inside of the composite board.

[0031] As an embodiment of the present invention, the number of layers of the anchor structure may be more than 1 layer, or may be 2 layers or 3 layers, which can be determined according to actual needs. As an embodiment of the present invention, when the number of layers of the anchor structure is more than 2 layers, the multi-layer anchor structures may be arranged at intervals, and the anchor arrangement between two adjacent layers of anchor structures may have an orientation angle; the orientation angle may be 0 to ±90°, which can be determined according to actual needs. In an embodiment of the present invention, the orientation angle may specifically be 0°, ±30°, ±45° or 90°. In the present invention, the mechanical properties of the plant fiber anchor composite board are further improved by limiting the number of layers of the anchor structure.

[0032] As an embodiment of the present invention, each layer of the embedded reinforcement structure can be a grid structure with staggered reinforcements or a structure with reinforcements of different thicknesses intertwined and arranged in parallel. In the present invention, by making the reinforcements secondary compound to form a composite structure with a specific structure, it is beneficial to further improve the mechanical properties of the plate.

[0033] As an embodiment of the present invention, in the grid structure in which the reinforcing ribs are arranged in an alternating manner, the grid spacing of the grid structure can be 2-20 mm, 5-15 mm, or 10-12 mm; the grid surface density of the grid structure can be 30-180 gsm, 50-150 gsm, or 100-120 gsm; in the structure in which the reinforcing ribs of different thicknesses are intertwined and arranged in parallel, the thick reinforcing ribs can be wrapped around the outside of the thin reinforcing ribs; the diameter of the thick reinforcing ribs can be 0.5-5 mm, 1-4 mm, or 2-3 mm; the diameter of the thin reinforcing ribs can be 0.1-2 mm, 0.5-1.5 mm, or 0.8-1 mm; the mass ratio of the thick reinforcing ribs to the thin reinforcing ribs can be 1:(1-3), 1:(1-3), or 1:(1-3); the spacing distance of the parallel arrangement can be 2-50 nm, 5-15 mm, or 10-12 mm. In the present invention, by limiting the parameters of each anchor structure, the strength and toughness of the anchor structure are effectively improved, and the mechanical properties of the plate are further improved.

[0034] As an embodiment of the present invention, the reinforcing ribs may include main reinforcing ribs and compound reinforcing ribs; in terms of mass percentage, the main reinforcing ribs may be 60-100%, or 70-85%; the compound reinforcing ribs may be 0-40%, or 15-30%. In the present invention, by limiting the composition of the reinforcing ribs, the main reinforcing ribs and the compound reinforcing ribs are adapted to each other, so that the overall structure of the reinforcing ribs can withstand a greater load, avoid stress concentration on the main reinforcing ribs or the compound reinforcing ribs and fail to fully exert the bearing capacity, and further strengthen the mechanical properties of the reinforcing ribs.

[0035] As an embodiment of the present invention, the main reinforcing ribs may be bamboo strips, plant fiber yarns or plant fiber prepreg tapes; the diameter of the bamboo strips may be 2 to 300 filaments, 50 to 250 filaments, or 100 to 200 filaments; the length of the bamboo strips may be limited according to actual needs; the diameter of the plant fiber yarn may be 1 to 5 mm, 2 to 4 mm, or 2.5 to 3 mm; the thickness of the plant fiber prepreg tape may be 0.8 to 4 mm, 1 to 3.5 mm, or 2 to 3 mm; the width of the plant fiber prepreg tape may be 2 to 50 mm, 10 to 40 mm, or 20 to 30 mm; in an embodiment of the present invention, the main reinforcing ribs may specifically be bamboo yarns or bamboo fiber prepreg tapes.

[0036] As an embodiment of the present invention, the plant fiber yarn is a twisted or non-twisted plant fiber yarn.

[0037] As an embodiment of the present invention, the bamboo fiber prepreg tape may be a bamboo fiber prepreg tape prepared by a common preparation method in the prior art.

[0038] In an embodiment of the present invention, the preparation method of the bamboo fiber prepreg tape can be to immerse the bamboo fiber in an acetone solution of epoxy resin with a mass concentration of 50% to obtain the bamboo fiber prepreg tape; the mass content of epoxy resin in the bamboo fiber prepreg tape is 45%.

[0039] The present invention has no special limitation on the impregnation operation. The impregnation operation commonly used by those skilled in the art can be used to make the mass content of epoxy resin in the bamboo fiber prepreg tape reach 45%.

[0040] As an embodiment of the present invention, the composite reinforcement rib is metal wire, glass fiber, carbon fiber or basalt fiber; the diameter of the composite reinforcement rib can be 2-10 mm, 4-8 mm, or 5-6 mm; in an embodiment of the present invention, the composite reinforcement rib can be specifically stainless steel wire. In the present invention, by limiting the types of main reinforcement ribs and composite reinforcement ribs, the main reinforcement ribs and composite reinforcement ribs are adapted to achieve the synergistic effect of the two, and further improve the mechanical properties and dimensional stability of the plate.

[0041] As an embodiment of the present invention, the mass ratio of the composite board to the embedded steel structure can be 1:(0.05-0.2), or 1:(0.1-0.18), or 1:(0.12-0.15). In the present invention, by limiting the usage ratio of the composite board to the embedded steel structure, the embedded steel structure and the composite board work together to bear the external load together, and at the same time, the stress is more evenly distributed in the plant fiber embedded steel composite board, avoiding stress concentration, and further improving the mechanical properties of the board.

[0042] As an embodiment of the present invention, the thickness of the plant fiber reinforced composite board can be 0.3-50 mm, 5-40 mm, or 15-30 mm. In the present invention, by limiting the thickness of the plant fiber reinforced composite board, excessive compression and reduction of board performance can be avoided.

[0043] The board and the embedded steel bar structure in the plant fiber embedded steel bar composite board provided by the present invention are both prepared from plant fibers, which effectively improves the environmental performance of the composite board; at the same time, the composition of the composite board is limited, further improving the mechanical properties of the composite board.

[0044] The present invention also provides a method for preparing the plant fiber reinforced composite board described in the above technical solution, comprising:

[0045] The plant fiber reinforced resin composite board is obtained by embedding or semi-embedding the reinforcing bar structure layer into the plant fiber reinforced resin composite felt material for compression molding;

[0046] Alternatively, the plant fiber reinforced resin composite board is assembled and then pressed to obtain the plant fiber reinforced resin composite board.

[0047] In one technical solution of the present invention, the preparation method comprises: embedding or semi-embedding the anchor structure layer into a plant fiber reinforced resin composite felt material for press molding to obtain a plant fiber anchor composite board.

[0048] As an embodiment of the present invention, the plant fiber reinforced resin composite felt material may be obtained by mixing plant fibers with a resin matrix.

[0049] As an embodiment of the present invention, the plant fiber can be pretreated before use; the pretreatment includes washing, drying and crushing in sequence; the length of the plant fiber can be 3 to 10 cm, 5 to 9 cm, or 6 to 7 cm. In the present invention, by pretreating the plant fiber to a limited length, the uniformity of the dispersion of the plant fiber in the resin matrix is ​​ensured, and the mechanical properties of the composite board are further improved.

[0050] The present invention has no particular limitation on the operations of washing, drying and pulverizing, as long as the length of the plant fibers is within a specified range.

[0051] As an embodiment of the present invention, the resin matrix may be resin fiber.

[0052] The present invention has no special limitation on the mixing operation. The mixing operation commonly used by those skilled in the art can be used to evenly mix the plant fiber and the resin matrix.

[0053] As an embodiment of the present invention, after the mixing, air-laying and needle-punching are sequentially performed to obtain a felt material.

[0054] The present invention has no special limitation on the airflow laying and needling operations, and the airflow laying and needling operations commonly used by those skilled in the art may be adopted.

[0055] After obtaining the plant fiber reinforced resin composite felt material, the present invention embeds or semi-embeds the reinforcing bar structure layer into the plant fiber reinforced resin composite felt material for compression molding to obtain the plant fiber reinforcing bar composite board material.

[0056] As an implementation mode of the present invention, the embedded reinforcement structure layer is obtained by arranging reinforcing bars according to the required embedded reinforcement structure.

[0057] As an embodiment of the present invention, the reinforcing ribs may be pretreated before use; the pretreatment may be plasma treatment, alkali treatment, coupling agent treatment or coating with an adhesive; the adhesive may be a resin adhesive, a rubber adhesive, a hot melt adhesive or a water-based adhesive. In an embodiment of the present invention, the alkali treatment may be specifically a sodium hydroxide treatment or a calcium hydroxide treatment; the coupling agent treatment may be specifically a silane coupling agent KH550 treatment or an isopropyl triphthalate treatment; the resin adhesive may be specifically an epoxy resin, a phenolic resin or a polyurethane resin; the rubber adhesive may be specifically a chloroprene rubber or a nitrile rubber; the hot melt adhesive may be specifically an ethylene-vinyl acetate copolymer or a polyamide; the water-based adhesive may be specifically a polyvinyl alcohol or an acrylic emulsion.

[0058] As an embodiment of the present invention, the target-substrate distance of the plasma treatment can be 2-10 mm, 4-8 mm, or 5-6 mm; the time of the plasma treatment can be 10-300 s, 50-250 s, or 100-200 s; the device for the plasma treatment can be a dielectric barrier discharge plasma device; the power of the plasma treatment can be 50-500 W, 100-400 W, or 200-300 W; the temperature of the plasma can be 90-120° C., 95-110° C., or 100-105° C. In the present invention, by limiting the process parameters of the plasma treatment, the treatment effect on the reinforcing ribs is effectively guaranteed, and the performance of the reinforcing ribs is further improved.

[0059] As an embodiment of the present invention, the alkali treatment may be immersing the reinforcing ribs in an alkali solution; and the coupling agent treatment may be immersing the reinforcing ribs in a coupling agent solution.

[0060] As an embodiment of the present invention, stirring or ultrasound can be performed during the alkali treatment and coupling agent treatment; the stirring rate can be 100-500rpm / min, 200-400rpm / min, or 300-350rpm / min; the ultrasound power can be 100-500W, and can also be specifically adjusted according to the equipment and the amount of reinforcement treatment. In the present invention, by limiting the process parameters of stirring or ultrasound treatment performed simultaneously with the alkali treatment and coupling agent treatment, the treatment effect on the reinforcement can be effectively guaranteed, and the performance of the reinforcement can be further improved.

[0061] In an embodiment of the present invention, the mass ratio of sodium hydroxide to the reinforcing rib in the sodium hydroxide solution in the sodium hydroxide treatment can be 1:(5-20), or 1:(8-15), or 1:(10-12); the temperature of the sodium hydroxide treatment can be 70-90°C, or 75-85°C, or 78-80°C; the time of the sodium hydroxide treatment can be 2-6h, or 3-5h, or 4-4.5h.

[0062] In an embodiment of the present invention, the mass ratio of calcium hydroxide and reinforcing ribs in the calcium hydroxide solution in the calcium hydroxide treatment can be 1:(3-5), or 1:(3.5-4.5), or 1:(3.8-4); the temperature of the calcium hydroxide treatment can be 60-80°C, or 65-75°C, or 68-70°C; the time of the calcium hydroxide treatment can be 3-8h, or 4-7h, or 5-6h.

[0063] In an embodiment of the present invention, the mass ratio of silane coupling agent KH550 and reinforcing rib in the silane coupling agent KH550 solution in the silane coupling agent KH550 treatment can be (0.5-3):100, or (1-2.5):100, or (1.5-2):100; the temperature of the silane coupling agent KH550 treatment can be 40-60°C, or 45-55°C, or 48-50°C; the time of the silane coupling agent KH550 treatment can be 1-3h, or 1.5-2.5h, or 2-2.3h.

[0064] In an embodiment of the present invention, the mass ratio of isopropyl triphthalate and reinforcing ribs in the isopropyl triphthalate solution in the isopropyl triphthalate treatment can be (0.3-2):100, or (0.5-1.5):100, or (0.8-1):100; the temperature of the isopropyl triphthalate treatment can be 50-70°C, or 55-65°C, or 58-60°C; the time of the isopropyl triphthalate treatment can be 1.5-4h, or 2-3.5h, or 2.5-3h. In the present invention, by limiting the process parameters of the reinforcing rib pretreatment operation process, the surface properties of the reinforcing ribs are improved, the mechanical properties of the implanted rib structure are further improved, and the bonding properties of the implanted rib structure and the felt material are improved, and the performance of the composite board is further improved.

[0065] As an embodiment of the present invention, after the alkali treatment impregnation and the coupling agent treatment impregnation are completed, post-treatment may be performed; the post-treatment may include liquid removal and drying performed in sequence.

[0066] As an embodiment of the present invention, the liquid removal can be performed by extrusion, filtration or centrifugation. The present invention has no special limitation on the operations of extrusion, filtration and centrifugation, and any operation capable of removing excess alkaline solution and coupling agent solution on the surface of the reinforcing rib is sufficient.

[0067] As an embodiment of the present invention, the drying temperature can be 40-100°C, 50-80°C, or 60-70°C; the present invention has no special limitation on the drying time, as long as the alkali treatment solution or the coupling agent treatment solution in the reinforcing rib can be completely removed so that the reinforcing rib reaches a constant weight.

[0068] As an embodiment of the present invention, the amount of the binder in the coating binder can be 100 to 250 g / m 2 , can also be determined according to the type of binder, surface roughness and porosity.

[0069] As an embodiment of the present invention, the post-treatment after coating the binder is the same as the post-treatment after the alkali treatment impregnation and the coupling agent treatment impregnation are completed, and will not be described in detail here.

[0070] As an embodiment of the present invention, before the reinforcing bar structure layer is embedded or semi-embedded in the plant fiber reinforced resin composite felt material, the reinforcing bar structure layer can be fixed by bonding or needle piercing with a high temperature resistant adhesive tape. In the present invention, fixing the reinforcing bar structure layer can effectively prevent the reinforcing bar structure layer from slipping when being composited with the plant fiber reinforced resin composite felt material.

[0071] As an embodiment of the present invention, the press molding can be hot press molding and cold press molding performed sequentially; the temperature of the hot press molding can be 120-180°C, 130-160°C, or 140-150°C; the pressure of the hot press molding can be 5-15MPa, 8-12MPa, or 9-10MPa; the time of the hot press molding can be 5-20min, 10-18min, or 12-15min; the pressure of the cold press molding can be 10-20MPa, 12-18MPa, or 15-16MPa; the time of the cold press molding can be 20-40min, 25-35min, or 30-32min. In the present invention, the resin is converted from a molten state to a glassy state by first hot pressing and then cold pressing, which effectively prevents warping and deformation caused by internal stress of the board, and further improves the mechanical properties of the composite board; by limiting the process parameters of the pressing process, the bonding force between the embedded steel structure layer and the felt material is effectively improved, and the strength and toughness of the plant fiber embedded steel composite board are further improved, while the dimensional stability of the plant fiber embedded steel composite board is further improved.

[0072] As an embodiment of the present invention, after the pressing and forming, the composite board can be cut, polished and surface treated in sequence, and the surface of the composite board can also be coated as needed; the coating treatment includes coating with waterproof paint or coating with fire retardant paint.

[0073] The present invention has no special limitation on the cutting, grinding and surface treatment, and they can be performed according to actual needs and using operations commonly used by those skilled in the art.

[0074] In another technical solution of the present invention, the preparation method includes: mixing the plant fiber and the resin matrix and then performing a first press molding to obtain a plate; assembling the rebar-embedded structural layer and the plant fiber-reinforced resin composite plate and then performing press molding to obtain a plant fiber rebar-embedded composite plate.

[0075] As an embodiment of the present invention, the plant fiber reinforced resin composite board may be a board obtained by mixing plant fibers with a resin matrix and then pressing and molding the mixed materials.

[0076] As an embodiment of the present invention, the pretreatment operation of the plant fiber before use is the same as the pretreatment operation of the aforementioned plant fiber, which will not be described in detail herein.

[0077] As an embodiment of the present invention, the resin matrix may be resin.

[0078] As an embodiment of the present invention, the mixing operation is the same as the aforementioned mixing operation, which will not be described in detail herein.

[0079] As an embodiment of the present invention, after the mixing, air-laying and needle-punching are sequentially performed to obtain a felt material.

[0080] As an embodiment of the present invention, the air-laying and needling operations are the same as the aforementioned mixing operations, which will not be described in detail herein.

[0081] As an embodiment of the present invention, the press molding may include hot press molding and cold press molding performed sequentially; the temperature of the hot press molding may be less than 200°C, which may be determined according to the type of the resin matrix; the time of the hot press molding may be 120 to 180s, 130 to 160s, or 140 to 150s; the pressure of the hot press molding may be 2 to 5MPa, or 3 to 4MPa; the time of the cold press molding may be 1 to 5min, and the pressure of the cold press molding may be 2 to 5MPa, or 3 to 4MPa. In an embodiment of the present invention, when the resin matrix is ​​polyethylene, the temperature of the hot press molding may be specifically 105 to 135°C; when the resin matrix is ​​polypropylene, the temperature of the hot press molding may be specifically 160 to 175°C; when the resin matrix is ​​soft PVC, the temperature of the hot press molding may be specifically 80 to 130°C; when the resin matrix is ​​hard PVC, the temperature of the hot press molding may be specifically 160 to 180°C. In the present invention, by limiting the process parameters of hot pressing of the felt material, it is ensured that the raw materials in the felt material can be effectively melted and mixed, thereby further improving the mechanical properties of the board.

[0082] After obtaining the plant fiber reinforced resin composite board, the present invention assembles the bar implantation structure layer and the plant fiber reinforced resin composite board and then performs press molding to obtain the plant fiber bar implantation composite board.

[0083] As an embodiment of the present invention, the preparation of the reinforcing rib layer and the pretreatment operation of the reinforcing ribs are the same as the preparation and pretreatment operation of the aforementioned reinforcing ribs, which will not be repeated here.

[0084] As an implementation mode of the present invention, before the reinforcing bar implant structure layer and the plant fiber reinforced resin composite board are assembled, the reinforcing bar implant structure layer can be fixed by bonding with a high temperature resistant adhesive tape or by acupuncture.

[0085] As an embodiment of the present invention, the press-forming operation is the same as the press-forming operation of the aforementioned reinforcing bar implant structure layer and the plant fiber reinforced resin composite felt material, and will not be described in detail herein.

[0086] As an embodiment of the present invention, the treatment after the press forming is the same as the treatment after the press forming of the aforementioned embedded reinforcement structure layer and the plant fiber reinforced resin composite felt material, which will not be repeated here.

[0087] The present invention pre-treats the raw materials of the composite plate, thereby effectively improving the surface properties of the raw materials of the composite plate and enhancing the bonding strength between the raw materials; at the same time, it limits the specific pressing process of the plate and the reinforcing bar structure, thereby further enhancing the bonding strength between the two, and further improving the mechanical properties and dimensional stability of the composite plate.

[0088] The present invention also provides the application of the plant fiber embedded steel bar composite board described in the above technical scheme or the plant fiber embedded steel bar composite board prepared by the preparation method described in the above technical scheme in transportation, low-altitude economy, building decoration, furniture manufacturing and packaging.

[0089] In order to further illustrate the present invention, the plant fiber embedded steel bar composite board provided by the present invention and its preparation method and application are described in detail below in combination with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0090] Example 1

[0091] A plant fiber reinforced composite board, comprising a composite board and a reinforced structure arranged inside the composite board, wherein the composite board is composed of polylactic acid fibers and bamboo fibers dispersed in the polylactic acid fibers; the reinforced structure is a grid structure in which bamboo fiber yarns are staggered; and the mass ratio of the reinforced structure to the composite board is 0.1:1;

[0092] The preparation method of the plant fiber reinforced composite board comprises the following steps:

[0093] (1) washing the bamboo fibers, drying them in a drying oven at 103° C. to constant weight, and then crushing them into pieces with a pulverizer to a length of 5 to 8 cm, mixing 30% by weight of the pretreated bamboo fibers with 70% by weight of polylactic acid fibers, and then sequentially performing air-laying and needle punching to obtain a plant fiber reinforced resin composite felt;

[0094] (2) The non-twisted bamboo fiber yarn with a diameter of 1.5 mm was immersed in a silane coupling agent KH550 solution at 40°C for 3 hours, wherein the mass ratio of the bamboo fiber yarn to the silane coupling agent KH550 in the silane coupling agent KH550 solution was 100:2, and after the impregnation was completed, the excess solution on the surface of the bamboo fiber yarn was removed by squeezing, and the bamboo fiber yarn after the impregnation was dried at 103°C until it reached a constant weight, and the pre-treated bamboo yarn was woven into a staggered grid structure to obtain a reinforcement structure layer; wherein the grid spacing was 5 mm;

[0095] (3) A single layer of the rebar-embedded structural layer obtained in step (2) is embedded in the plant fiber reinforced resin composite felt material obtained in step (1), firstly hot-pressed at 160° C. and 10 MPa for 12 min, and then cold-pressed at 10 MPa for 20 min. After the pressing is completed, the rebar-embedded composite board is cut, polished and surface treated to obtain a plant fiber rebar-embedded composite board with a thickness of 8 mm.

[0096] Example 2

[0097] A plant fiber reinforced composite board Figures 1 to 3As shown, it is composed of a composite board and a reinforcing bar structure arranged on the surface of the composite board, wherein the composite board is composed of polypropylene and hemp fibers and wheat straw fibers dispersed in the polypropylene; the reinforcing bar structure is a grid structure in which bamboo yarns are arranged radially and glass fibers are arranged in a weft direction; the mass ratio of the reinforcing bar structure to the composite board is 0.15:1;

[0098] The preparation method of the plant fiber reinforced composite board comprises the following steps:

[0099] (1) washing hemp fiber and wheat straw fiber in a mass ratio of 1:1, drying them in a drying oven at 103° C. to constant weight, and then crushing them into a length of 4 to 7 cm using a pulverizer, mixing 40% by mass of a mixed fiber of pretreated hemp fiber and wheat straw fiber with 60% by mass of polypropylene, and then sequentially performing air-laying and needle punching to obtain a felt material, and first hot-pressing the felt material at 170° C. and 4 MPa for 3 min, and then cold-pressing the felt material at 4 MPa for 1 min, to obtain a plant fiber reinforced resin matrix board;

[0100] (2) 60% by mass of bamboo yarn with a diameter of 2 mm and 40% by mass of glass fiber with a diameter of 1.2 mm are immersed in a sodium hydroxide solution at 70° C. for sodium hydroxide treatment for 4 hours, wherein the mass ratio of the mixture of bamboo yarn and glass fiber to the sodium hydroxide in the sodium hydroxide solution is 12.5:8, and after the immersion is completed, the excess solution on the surface of the bamboo yarn and glass fiber is removed by squeezing, and the bamboo yarn and glass fiber after the immersion are dried at 103° C. until the impregnated bamboo yarn and glass fiber reach a constant weight. After the pretreatment is completed, the bamboo yarn is radially woven and the glass fiber is weft-woven into a staggered grid structure to obtain a reinforcement structure layer; wherein the grid spacing is 10 mm;

[0101] (3) Assembling the rebar-embedded structure layer obtained in step (2) and the plant fiber-reinforced resin matrix plate obtained in step (1), first hot-pressing the plate at 150° C. and 12 MPa for 30 min, and then cold-pressing the plate at 15 MPa for 25 min. After the pressing, the plate is cut, polished and surface treated to obtain a plant fiber rebar-embedded composite plate with a thickness of 8 mm; wherein the mass ratio of the plate to the rebar-embedded structure is 1:0.15.

[0102] Example 3

[0103] A plant fiber reinforced composite board, comprising a composite board and a reinforced structure arranged on the surface of the composite board, wherein the composite board is composed of polycarbonate fibers and rice straw dispersed in the polycarbonate fibers; the reinforced structure is a bamboo fiber prepreg tape and a stainless steel wire parallel arrangement structure; the mass ratio of the reinforced structure to the composite board is 0.08:1;

[0104] The preparation method of the plant fiber reinforced composite board comprises the following steps:

[0105] (1) washing the rice straw, drying it in a drying oven at 103° C. to constant weight, and then crushing it into pieces with a pulverizer to a length of 3 to 6 cm, mixing 50% by weight of the pretreated rice straw with 50% by weight of polycarbonate fiber, and then sequentially performing air-laying and needle punching to obtain a plant fiber reinforced resin matrix felt material;

[0106] (2) 80 g / m2 of bamboo fiber prepreg tape with a mass percentage of 80%, a width of 5 mm, and a thickness of 2 mm and a stainless steel wire with a mass percentage of 20% and a diameter of 1 mm were coated on the surface of the prepreg tape. 2 After the coating is completed, the epoxy resin on the surface of the bamboo fiber prepreg tape and the stainless steel wire is removed by extrusion, and the bamboo fiber prepreg tape and the stainless steel wire after the epoxy resin coating are dried at 60°C until they reach a constant weight, and the stainless steel wire after the pretreatment is wound around the surface of the bamboo fiber prepreg tape to form a composite reinforcement rib such as Figures 4-5 As shown, the composite reinforcing ribs are arranged in parallel to obtain a reinforcing bar structure layer; wherein the spacing of the parallel arrangement structure is 10 mm;

[0107] (3) The two layers of the embedded steel bar structure obtained in step (2) are embedded in the plant fiber reinforced resin matrix felt material obtained in step (1), wherein the orientation angle between the two layers of the embedded steel bar structure is 30°, and the material is first hot-pressed at 180°C and 8MPa for 15 minutes, and then cold-pressed at 15MPa for 20 minutes. After the pressing is completed, the material is cut, polished and surface treated to obtain a plant fiber embedded steel bar composite board with a thickness of 15 mm; wherein the mass ratio of the board to the embedded steel bar structure is 1:0.08.

[0108] Comparative Example 1

[0109] The difference between Comparative Example 1 and Example 1 is that the embedded reinforcement structure is omitted and the board is composed of bamboo fiber and polylactic acid fiber. The rest is the same as Example 1.

[0110] Comparative Example 2

[0111] The difference between Comparative Example 2 and Example 2 is that the embedded reinforcement structure is omitted, and the board is composed of hemp fiber, wheat straw fiber, polypropylene and polypropylene fiber. The rest is the same as Example 2.

[0112] Comparative Example 3

[0113] The difference between Comparative Example 3 and Example 3 is that the embedded reinforcement structure is omitted and the plate is made of rice straw and polycarbonate fiber. The rest is the same as Example 3.

[0114] The bending properties of the plant fiber reinforced composite plates obtained in Examples 1 to 3 and the plates obtained in Comparative Examples 1 to 3 were tested using a universal mechanical testing machine, the testing standard was GB / T 1449-2005, and the testing speed was 2 mm / min; the sample size of the composite plates of Examples 1 to 2 and the plates of Comparative Examples 1 to 2 was 160 mm×15 mm×8 mm, and the span was 128 mm, and the sample size of the composite plates of Example 3 and the plates of Comparative Example 3 was 300 mm×20 mm×15 mm, and the span was 240 mm;

[0115] The impact properties of the plant fiber embedded steel bar composite plates obtained in Examples 1 to 3 and the plates obtained in Comparative Examples 1 to 3 were tested using a universal mechanical testing machine. The testing standard was ASTMD6110-10, the impact energy was 2.7 J, and the impact velocity was 3.46 m / s. The sample size of the composite plates of Examples 1 to 2 and the plates of Comparative Examples 1 to 2 was 80 mm × 12.7 mm × 8 mm, and the sample size of the composite plates of Example 3 and the plates of Comparative Example 3 was 80 mm × 12.7 mm × 12.7 mm.

[0116] The testing standard for the 24h water absorption thickness expansion rate of the plant fiber embedded steel bar composite board obtained in Examples 1 to 3 and the board obtained in Comparative Examples 1 to 3 is GB / T 17657-2013;

[0117] The mechanical properties results are shown in Table 1.

[0118] Table 1 Mechanical properties of the plant fiber reinforced composite board obtained in Examples 1 to 3 and the board obtained in Comparative Examples 1 to 3

[0119] Example Bending strength / MPa Flexural modulus / MPa <![CDATA[Impact strength / KJ·m -2 > 24h water absorption thickness expansion rate / % Example 1 10.25 721.56 8.32 1.2 Example 2 12.31 1206.33 9.24 0.5 Example 3 14.96 2231.54 9.56 0.3 Comparative Example 1 5.73 260.52 2.31 25.30 Comparative Example 2 7.64 431.28 4.41 10.08 Comparative Example 3 12.70 524.91 8.73 6.93

[0120] It can be seen from Table 1 that under the same conditions of the base plate, adding a reinforcing bar structure can effectively improve the mechanical properties and dimensional stability of the composite plate.

[0121] The shielding parameters of Example 3 and Comparative Example 3 were tested using a vector network analyzer, and the electromagnetic shielding effectiveness was calculated according to the following formula; the electromagnetic shielding effectiveness of Example 3 was 26 dB; the electromagnetic shielding effectiveness of Comparative Example 3 was 9 dB;

[0122] R=|S 11 | 2 =|S 22 | 2

[0123] T=|S 21 | 2 =|S 12 | 2

[0124] A=1-TR

[0125] SE R =-10×lg(1-R)

[0126]

[0127] SE total =SE A +SE R +SE m

[0128] Where S11, S22, S21 and S12 are shielding parameters tested by vector network analyzer; R is reflected power; T is transmitted power; A is absorbed power; SE R is the electromagnetic wave reflection loss; SE A is the electromagnetic wave absorption loss; SE m is the electromagnetic wave multi-layer reflection loss; SE total is the total electromagnetic shielding effectiveness.

[0129] The thermal conductivity of Example 3 and Comparative Example 3 was tested using a Hot Disk thermal constant analyzer (2500-OT, Hot Disk, Sweden); the thermal conductivity of Example 3 was 0.58 W / mK, and the thermal conductivity of Comparative Example 3 was 0.20 W / mK.

[0130] It can be seen from this that the embedded reinforcement structure provided by the present invention can effectively improve the electromagnetic shielding performance and thermal conductivity of the composite board.

[0131] 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 plant fiber rebar-embedded composite board, comprising a composite board and a rebar-embedded structure arranged on the surface or inside of the composite board; the composite board comprises a resin matrix and plant fibers dispersed in the resin matrix.

2. The plant fiber reinforced composite board according to claim 1, characterized in that: The mass ratio of the composite board to the embedded reinforcement structure is 1:(0.05-0.2).

3. The plant fiber reinforced composite board according to claim 1, characterized in that: The number of layers of the reinforcing bar implant structure is more than one.

4. The plant fiber reinforced composite board according to claim 3, characterized in that: Each layer of the embedded reinforcement structure is independently a grid structure in which reinforcement bars are arranged in a staggered manner or a structure in which reinforcement bars of different thicknesses are intertwined and arranged in parallel.

5. The plant fiber reinforced composite board according to claim 4, characterized in that: Calculated by mass percentage, the reinforcing ribs include 60-100% of main reinforcing ribs and 0-40% of compound reinforcing ribs.

6. The plant fiber reinforced composite board according to claim 5, characterized in that: The main reinforcing ribs are bamboo strips, plant fiber yarns or plant fiber prepreg tapes; the composite reinforcing ribs are metal wires, glass fibers, carbon fibers or basalt fibers.

7. The plant fiber reinforced composite board according to claim 1, characterized in that: Calculated by mass percentage, the composite board comprises 5-85% of plant fiber and 15-95% of resin matrix.

8. The plant fiber reinforced composite board according to claim 7, characterized in that: The plant fiber is one or more of bamboo fiber, hemp fiber, crop straw, cotton fiber, bagasse fiber, palm fiber, coconut shell fiber and banana fiber; the resin matrix is ​​resin fiber or resin.

9. The method for preparing the plant fiber reinforced composite board according to any one of claims 1 to 8, comprising: The plant fiber reinforced resin composite board is obtained by embedding or semi-embedding the reinforcing bar structure layer into the plant fiber reinforced resin composite felt material for compression molding; Alternatively, the plant fiber reinforced resin composite board is assembled and then pressed to obtain the plant fiber reinforced resin composite board.

10. Application of the plant fiber reinforced composite board according to any one of claims 1 to 8 or the plant fiber reinforced composite board prepared by the preparation method according to claim 9 in transportation, low-altitude economy, building decoration, furniture manufacturing and packaging.

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