Natural cellulose modified carbon fiber metal laminate and preparation method thereof

Abstract

The invention discloses a natural cellulose modified carbon fiber metal laminate and a preparation method thereof, comprising a first metal laminate and a second metal laminate with the same structure, wherein the first metal laminate and the second metal laminate are a five-layer structure; the first metal laminate and the second metal laminate are composed of a panel a, a sandwich panel a, a sandwich panel b, a sandwich panel b and a panel c, wherein the panel a, the panel b and the panel c are magnesium alloy panels, the sandwich panel a and the sandwich panel b are carbon fiber panels, and the panels and the sandwich panels are bonded to form a complete structure by resin glue; the sandwich panel a and the sandwich panel b are formed by hot pressing epoxy resin and carbon fiber cloth; the method comprises the following steps: S1 material preparation, S2 material preparation, S3 plate paving and S4 plate synthesis; the method improves the performance of the epoxy resin by using cellulose extracted from natural indocalamus leaves, and the performance between the layers is transitioned in a certain way, thereby optimizing energy transfer and significantly improving stiffness, strength and overall performance.

Description

Technical Field

[0001] The present invention relates to the technical field of modified carbon fiber metal laminates, in particular to a natural cellulose modified carbon fiber metal laminate and a preparation method thereof. Background Art

[0002] Fiber-metal laminates are widely used in high-tech fields such as aerospace, automobiles, and national defense. Fiber-metal laminates combine the fatigue resistance and high specific strength of fibers with the fracture toughness and impact resistance of metals, making them a lightweight material with excellent performance.

[0003] In existing technologies, carbon fiber-metal laminates can improve their performance by adding reinforcing fillers to the fiber composite matrix of the fiber-metal laminate. However, fiber composite materials typically have high longitudinal tensile strength but poor flexural properties. Therefore, a natural cellulose-modified carbon fiber-metal laminate and its preparation method are needed to address these issues. Summary of the Invention

[0004] The object of the present invention is to provide a natural cellulose modified carbon fiber metal laminate and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a natural cellulose modified carbon fiber metal laminate, comprising a first metal laminate and a second metal laminate of the same structure, wherein the first metal laminate and the second metal laminate are a five-layer structure;

[0006] The first metal laminate and the second metal laminate are composed of a panel a, a sandwich panel a, a sandwich panel b, a sandwich panel b and a panel c, wherein the panel a and the panel b are magnesium alloy panels, the sandwich panel a and the sandwich panel b are carbon fiber panels, and the panel and the sandwich panel are bonded by resin glue to form a complete structure;

[0007] The sandwich panels a and b are formed by hot pressing epoxy resin and carbon fiber cloth;

[0008] The first metal laminate and the second metal laminate b are externally provided with an edge layer, and both sides of the outer wall of the edge layer are provided with a splicing strip;

[0009] The side walls of the splicing strips on both sides are provided with arc-shaped holes, and arc-shaped insertion rods are inserted into the arc-shaped holes;

[0010] The upper side walls of the splicing strips on both sides are provided with countersunk grooves, and the countersunk grooves are connected to the arc-shaped holes;

[0011] A limiting cap is installed in the countersunk groove, and a screw barrel is installed at the lower end of the limiting cap, and the screw barrel is sleeved on the outside of the arc-shaped insertion rod;

[0012] The outer portion of the screw barrel is located at the lower end of the limiting cap and is sheathed with a rubber pad a and a rubber pad b.

[0013] Preferably, a rubber block is installed on the side wall of the rubber pad a facing the rubber pad b, and the outer diameters of the rubber pad a and the rubber pad b are both larger than the inner diameter of the arc-shaped hole.

[0014] Preferably, the inner wall of the screw barrel is provided with an internal thread, the outer wall of the end of the arc-shaped insertion rod is provided with an external thread, and the internal thread matches the external thread.

[0015] Preferably, the side walls of the splicing strips on both sides are provided with slots, and the edging layer is snapped into the slots.

[0016] Preferably, hook seats are installed on the outer walls of the splicing strips on both sides, and a rotation cavity is opened on the side wall of the hook seat, and a hook is clamped in the rotation cavity.

[0017] A method for preparing a natural cellulose modified carbon fiber metal laminate comprises the following steps: S1 material preparation, S2 material preparation, S3 plate laying, and S4 plate synthesis;

[0018] Step S1: Material preparation design includes the following steps:

[0019] S11: Material preparation. The carbon fiber reinforced resin composite panels of sandwich panels a and b are modified carbon fiber composite materials with a gradient mass fraction of indocalamus cellulose. The carbon fiber panels are formed by hot pressing indocalamus cellulose-modified epoxy resin and carbon fiber cloth.

[0020] S12: Material cutting: After designing in step S11, panel a and panel b are cut by a shearing machine;

[0021] Step S2: Material preparation includes the following steps:

[0022] S21: Material processing, the indigo leaf cellulose is prepared by drying fresh indigo leaves for 30 days, crushing and screening, chemically treating, washing and drying, etc.;

[0023] Fresh indigo leaves are dried for 30 days, crushed in a grinder for 10-30 minutes, and then sieved with a sieve. The crushed indigo leaves are then ball-milled for 40-60 minutes using a ball mill; the treated indigo leaf fine powder is soaked in a 5wt.% NaOH solution for 4-5 hours; after soaking, the indigo leaf fine powder is repeatedly washed with clean water, and then placed in an oven and dried at 90-100°C; after drying, the powder is sieved again to obtain indigo leaf fiber powder;

[0024] Step S3 of adding additional plates includes the following steps:

[0025] S31: Hot pressing molding, carbon fiber reinforced resin composite plate is prepared by hot pressing molding, and the lamination method is unidirectional laying of carbon fiber cloth coated with epoxy resin, with a total of 16 layers;

[0026] S32: hot pressing preparation, placing the carbon fiber cloth coated with indocalamus cellulose modified epoxy resin into a mold, then placing the magnesium alloy plates on the upper and lower sides of the carbon fiber cloth, and then placing the whole into a hot press for pressing;

[0027] S33: Board synthesis: Place the carbon fiber cloth coated with indigo cellulose modified epoxy resin into a mold, then place the magnesium alloy plates on the upper and lower sides of the carbon fiber cloth, and then put the whole into a hot press for pressing. Curing treatment is carried out at 160-180℃ and 1-3 MP for 3-4 h to obtain the indigo cellulose modified carbon fiber-magnesium alloy laminate.

[0028] Preferably, the step S21 of selecting materials further includes: the mass fraction of indigo cellulose in the modified epoxy resin changes gradually along the thickness direction, the mass fraction of indigo fiber ranges from 10wt.% to 25wt.%, and the mass fraction of indigo fiber differs by 5% between each layer;

[0029] The magnesium alloy plate in step S3 is an AZ31 rolled plate, and its chemical composition mainly includes an aluminum (Al) content of 2.5-3.5%, a zinc (Zn) content of 0.6-1.4%, and a magnesium (Mg) content as the balance.

[0030] Preferably, the gradient varies according to the following function:

[0031] C1=10+5(n-1)X100% (n is the number of carbon fiber layers, n=1, 2, 3, 4)

[0032] C2=25-5(n-5)X100% (n is the number of carbon fiber layers, n=5, 6, 7, 8)

[0033] C3=10+5(n-9)X100% (n is the number of carbon fiber layers, n=9, 10, 11, 12)

[0034] C4=25-5(n-13)X100% (n is the number of carbon fiber layers, n=13, 14, 15, 16).

[0035] Preferably, the cellulose is added to a 50-70 ml acetone solution and ultrasonically dispersed for 30-40 minutes. The dispersed cellulose / acetone solution and epoxy resin are then ultrasonically stirred for 45-60 minutes to fully mix. The mixture is placed in an oven at 70-80°C to dry the acetone to obtain a cellulose / epoxy resin mixture. Subsequently, a curing agent is added at a mass ratio of 3:1 epoxy resin to curing agent and ultrasonically stirred for 30-40 minutes to obtain a cellulose-modified epoxy resin. The carbon fiber cloth is coated with the cellulose-modified epoxy resin, and then another layer of carbon fiber cloth is laid. This operation is repeated until 16 layers are stacked.

[0036] Preferably, the epoxy resin modified with indigo cellulose is dip-coated on a T300 carbon fiber cloth unidirectional tape, and four layers are laid in increasing order from 5% to 25% indigo fiber mass fraction, with the bottom layer being an epoxy resin with a 5% indigo cellulose mass fraction and the top layer being an epoxy resin with a 25% indigo cellulose mass fraction. The gradient order is then changed symmetrically every four layers, resulting in a total of 16 layers of carbon fiber cloth dipped in indigo cellulose modified epoxy resin. This and the magnesium alloy plate are placed in a mold in the order of faceplate-sandwich panel-faceplate-sandwich panel-faceplate, left to stand for 1 hour, and then cured at 160°C and 1 MPa for 5 hours to obtain a gradient structure carbon fiber metal laminate.

[0037] Compared with the existing technology, this solution designs a natural cellulose modified carbon fiber metal laminate and its preparation method, which has the following beneficial effects:

[0038] (1) Inspired by the ability of plant fibers to enhance epoxy resin, the present invention designs a carbon fiber laminate of indigofera fiber-modified epoxy resin. The front panel is a magnesium alloy plate, and the middle sandwich panel is a modified epoxy resin carbon fiber composite plate with a gradient concentration of indigofera cellulose. Indigofera fiber improves the performance of epoxy resin, and the performance between each layer is transitioned in a certain way, optimizing energy transfer and significantly improving stiffness, strength and overall performance.

[0039] (2) The panel and the sandwich panel of the present invention are bonded by using the epoxy resin modified with indigo cellulose, so that the panel and the sandwich panel are better connected and fixed, the delamination phenomenon between the layers is reduced, and the service life of the material is increased.

[0040] (3) The present invention uses indigo cellulose to enhance the performance of epoxy resin. Indigo fiber is a natural plant fiber with a simple preparation process, low cost, and no pollution. It also significantly improves the performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the structure of the present invention;

[0042] Figure 2 This is a schematic diagram of the splicing portion of the present invention;

[0043] Figure 3 This is a schematic structural diagram of part A of the present invention;

[0044] Figure 4 Design diagram for the composition gradient of each 4 layers of sandwich carbon fiber panels;

[0045] Figure 5 This is a diagram of a carbon fiber metal laminate;

[0046] Figure 6 Graph showing the bending strength of fiber metal laminates.

[0047] In the figure: 1 first metal laminate, 111 second metal laminate, 101 indocalamus cellulose modified epoxy resin, 102 carbon fiber cloth, 201 panel a, 202 sandwich panel a, 203 panel b, 204 sandwich panel b, 205 panel c, 2 edging layer, 3 splicing strip, 4 slot, 5 hook seat, 6 rotating cavity, 7 hook, 8 arc hole, 9 arc rod, 10 rubber block, 11 rubber pad a, 12 limiting cap, 13 countersunk groove, 14 rubber pad b, 15 screw barrel, 16 external thread. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] See also Figures 1 to 6 , a technical solution provided by the present invention: a natural cellulose modified carbon fiber metal laminate, comprising a first metal laminate 1 and a second metal laminate 111 having the same structure, characterized in that: the first metal laminate 1 and the second metal laminate 111 are a 5-layer structure;

[0050] The first metal laminate 1 and the second metal laminate 111 are composed of a panel a201, a sandwich panel a202, a sandwich panel b203, a sandwich panel b204 and a panel c205. The panels a201 and b203 are magnesium alloy panels, and the sandwich panels a202 and b204 are carbon fiber panels. The panels and the sandwich panels are bonded with resin glue to form a complete structure.

[0051] The sandwich panels a202 and b204 are formed by hot pressing of indocalamus cellulose modified epoxy resin 101 and carbon fiber cloth 102;

[0052] The first metal laminate 1 and the second metal laminate 111 are externally assembled with an edge layer 2, and both sides of the outer wall of the edge layer 2 are installed with a splicing strip 3;

[0053] The side walls of the two side splicing strips 3 are provided with arc-shaped holes 8, and arc-shaped insertion rods 9 are inserted into the arc-shaped holes 8;

[0054] The upper side walls of the two side splicing strips 3 are provided with countersunk grooves 13, and the countersunk grooves 13 are connected to the arc-shaped holes 8;

[0055] The countersunk groove 13 is equipped with a limiting cap 12, and the lower end of the limiting cap 12 is equipped with a screw barrel 15, which is sleeved on the outside of the arc-shaped insertion rod 9;

[0056] The outer portion of the screw barrel 15 is located at the lower end of the limiting cap 12 and is provided with a rubber pad a11 and a rubber pad b14;

[0057] According to different needs, two or more first metal laminates 1 and second metal laminates 111 of the same size can be spliced together. In this case, two metal laminates are selected for splicing. Figure 1 As shown, the edging layer 2 arranged around the outer walls of the two metal laminates is used to protect the four sides of the metal laminates, and the splicing strips 3 arranged at both ends are used for splicing. The splicing strip 3 on the right side of the metal laminate on one side and the splicing strip 3 on the left side of the metal laminate on the other side are opened with arc holes 8, and the two arc holes 8 have the same structure and opposite directions, so that the two are connected by the arc plug rod 9, and the arc plug rod 9 is fixed by the limiting cap 12, and then the two metal laminates are spliced, and rubber pads a 11 and rubber pads b 14 are set at the lower end of the limiting cap 12. When the limiting cap 12 is installed, the arc hole 8 will be sealed.

[0058] A rubber block 10 is installed on the side wall of the rubber pad a11 facing the rubber pad b14. The outer diameters of the rubber pad a11 and the rubber pad b14 are both larger than the inner diameter of the arc-shaped hole 8. The screw barrel 15 is installed by threaded engagement.

[0059] The inner wall of the screw barrel 15 is provided with an internal thread, and the outer wall of the end of the arc-shaped insertion rod 9 is provided with an external thread 16, and the internal thread and the external thread 16 are matched;

[0060] The side walls of the splicing strips 3 on both sides are provided with slots 4, and the edging layer 2 is snapped into the slots 4;

[0061] The outer walls of the splicing strips 3 on both sides are provided with hook seats 5, the side walls of the hook seats 5 are provided with rotation cavities 6, and the rotation cavities 6 are provided with hooks 7;

[0062] Install the edging layer 2 on the outside of the metal laminate, then install the splicing strips 3 on both sides of the edging layer 2, then align the two processed metal laminates left and right, align the arc-shaped holes 8, then insert the arc-shaped rod 9 into the arc-shaped hole 8, and then screw the screw barrel 15 to the end of the arc-shaped rod 9.

[0063] A method for preparing a natural cellulose modified carbon fiber metal laminate comprises the following steps: S1 material preparation, S2 material preparation, S3 plate laying, and S4 plate synthesis;

[0064] Step S1: Material preparation design includes the following steps:

[0065] S11: Material preparation. The carbon fiber reinforced resin composite panels of sandwich panels a and b are modified carbon fiber composite materials with a gradient mass fraction of indocalamus cellulose. The carbon fiber panels are formed by hot pressing epoxy resin and carbon fiber cloth.

[0066] S12: Material cutting: After designing in step S11, panel a and panel b are cut by a shearing machine;

[0067] Step S2: Material preparation includes the following steps:

[0068] S21: Material processing, the indigo leaf cellulose is prepared by drying fresh indigo leaves for 30 days, crushing and screening, chemically treating, washing and drying, etc.;

[0069] Fresh indigo leaves are dried for 30 days, crushed in a grinder for 10-30 minutes, and then sieved with a sieve. The crushed indigo leaves are then ball-milled for 40-60 minutes using a ball mill; the treated indigo leaf fine powder is soaked in a 5wt.% NaOH solution for 4-5 hours; after soaking, the indigo leaf fine powder is repeatedly washed with clean water, and then placed in an oven and dried at 90-100°C; after drying, the powder is sieved again to obtain indigo leaf fiber powder;

[0070] Step S3 of adding additional plates includes the following steps:

[0071] S31: Hot pressing molding, carbon fiber reinforced resin composite plate is prepared by hot pressing molding, and the lamination method is unidirectional laying of carbon fiber cloth coated with epoxy resin, with a total of 16 layers;

[0072] S32: hot pressing preparation, placing the carbon fiber cloth coated with indocalamus cellulose modified epoxy resin into a mold, then placing the magnesium alloy plates on the upper and lower sides of the carbon fiber cloth, and then placing the whole into a hot press for pressing;

[0073] S33: Board synthesis: Place the carbon fiber cloth coated with indigo cellulose modified epoxy resin into a mold, then place the magnesium alloy plates on the upper and lower sides of the carbon fiber cloth, and then put the whole into a hot press for pressing. Curing treatment is carried out at 160-180℃ and 1-3 MP for 3-4 h to obtain the indigo cellulose modified carbon fiber-magnesium alloy laminate.

[0074] Step S21 of selecting materials further includes: the mass fraction of indigo cellulose in the modified epoxy resin changes gradually along the thickness direction, the mass fraction of indigo fiber ranges from 10 wt.% to 25 wt.%, and the mass fraction of indigo fiber differs by 5% between each layer;

[0075] The magnesium alloy plate in step S3 is an AZ31 rolled plate, and its chemical composition mainly includes an aluminum (Al) content of 2.5-3.5%, a zinc (Zn) content of 0.6-1.4%, and a magnesium (Mg) content as the balance.

[0076] The gradient changes according to the following function:

[0077] C1=10+5(n-1)X100% (n is the number of carbon fiber layers, n=1, 2, 3, 4)

[0078] C2=25-5(n-5)X100% (n is the number of carbon fiber layers, n=5, 6, 7, 8)

[0079] C3=10+5(n-9)X100% (n is the number of carbon fiber layers, n=9, 10, 11, 12)

[0080] C4=25-5(n-13)X100% (n is the number of carbon fiber layers, n=13, 14, 15, 16).

[0081] Add indica cellulose to 50-70 ml of acetone solution and ultrasonically disperse for 30-40 minutes. Then, ultrasonically stir the dispersed indica cellulose / acetone solution and epoxy resin for 45-60 minutes to thoroughly mix. Place the mixture in an oven at 70-80°C to dry the acetone, resulting in an indica cellulose / epoxy resin mixture. Then, add curing agent at a mass ratio of 3:1 epoxy resin to curing agent and ultrasonically stir for 30-40 minutes to obtain indica cellulose-modified epoxy resin. Coat carbon fiber cloth with the indica cellulose-modified epoxy resin, then layer another layer of carbon fiber cloth. Repeat this process until 16 layers are stacked.

[0082] Example 1: Preparation of a gradient structure carbon fiber metal laminate:

[0083] Fresh indigo leaves were dried for 30 days, crushed in a grinder for 20 minutes, and then sieved with a sieve. The crushed indigo leaf powder was then ball-milled for 40 minutes using a ball mill. The treated indigo leaf fine powder was soaked in a 5wt.% NaOH solution for 4 hours. After soaking, the indigo leaf fine powder was repeatedly washed with clean water, then placed in an oven and dried at 90°C. After drying, it was sieved again to obtain indigo leaf fiber fine powder.

[0084] Epoxy resins reinforced with indigofera leaf fibers were prepared at varying mass fractions, ranging from 10 wt.% to 25 wt.%. The mass fractions of adjacent indigofera leaf fibers differed by 5 wt.%. Appropriate amounts of indigofera leaf cellulose powder were weighed and ultrasonically mixed with 50 ml of acetone solution at respective mass fractions of 10%, 15%, 20%, and 25% for 40 minutes. The mixture was then added to an appropriate amount of epoxy resin. After ultrasonic dispersion for 45 minutes, the mixture was placed in an oven and dried at 70°C for 4 hours. The resulting indigofera leaf fiber-epoxy resin mixture was then added with 10 g of curing agent and ultrasonically mixed for 30 minutes to obtain the indigofera leaf fiber-reinforced epoxy resin.

[0085] Indochine cellulose-modified epoxy resin was dip-coated onto a unidirectional T300 carbon fiber cloth tape. Four layers were applied, increasing the indochine fiber mass fraction from 5% to 25%. The bottom layer consisted of an epoxy resin with a 5% indochine cellulose mass fraction, and the top layer consisted of an epoxy resin with a 25% indochine cellulose mass fraction. The gradient order was then symmetrically alternating every four layers, resulting in a total of 16 layers of indochine cellulose-modified epoxy resin-coated carbon fiber cloth. This carbon fiber cloth and magnesium alloy sheet were placed in a mold in the order of faceplate-sandwich panel-faceplate-sandwich panel-faceplate. The laminate was then cured at 160°C and 1 MPa for 5 hours to produce a gradient carbon fiber metal laminate.

[0086] Example 2: Preparation of a gradient structure carbon fiber metal laminate:

[0087] Fresh indigo leaves were dried for 30 days, crushed in a grinder for 20 minutes, and then sieved with a sieve. The crushed indigo leaf powder was then ball-milled for 60 minutes using a ball mill. The treated indigo leaf fine powder was soaked in a 5wt.% NaOH solution for 5 hours. After soaking, the indigo leaf fine powder was repeatedly washed with clean water, then placed in an oven and dried at 90°C. After drying, it was sieved again to obtain indigo leaf fiber fine powder.

[0088] Indigo leaf fiber-reinforced epoxy resins were prepared with varying mass fractions, ranging from 10 wt.% to 25 wt.%. The mass fractions of adjacent groups of indigo leaf fibers differed by 5 wt.%. Appropriate amounts of indigo leaf cellulose powder were weighed and ultrasonically mixed with 50 ml of acetone solution at respective mass fractions of 10%, 15%, 20%, and 25% for 30 minutes. The mixture was then added to an appropriate amount of epoxy resin. After ultrasonic dispersion for 60 minutes, the mixture was placed in an oven and dried at 70°C for 4 hours. The resulting indigo leaf fiber-epoxy resin mixture was then added with 10 g of curing agent and ultrasonically mixed for 30 minutes to obtain the indigo leaf fiber-reinforced epoxy resin.

[0089] Indochine cellulose-modified epoxy resin was dip-coated onto a unidirectional T300 carbon fiber cloth tape. Four layers were applied, increasing the indochine fiber mass fraction from 5% to 25%. The bottom layer consisted of an epoxy resin with a 5% indochine cellulose mass fraction, and the top layer consisted of an epoxy resin with a 25% indochine cellulose mass fraction. The gradient order was then symmetrically alternating every four layers, resulting in a total of 16 layers of indochine cellulose-modified epoxy resin-coated carbon fiber cloth. This carbon fiber cloth was then placed in a mold with magnesium alloy plates in the order of faceplate-sandwich panel-faceplate-sandwich panel-faceplate. The laminate was then cured at 180°C and 3 MPa for 3 hours to produce a gradient carbon fiber metal laminate.

[0090] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0091] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A natural cellulose modified carbon fiber metal laminate, comprising a first metal laminate (1) and a second metal laminate (111) having the same structure, characterized in that: The first metal laminate (1) and the second metal laminate (111) are a five-layer structure; The first metal laminate (1) and the second metal laminate (111) are composed of a panel a (201), a sandwich panel a (202), a panel b (203), a sandwich panel b (204) and a panel c (205), wherein the panel a (201) and the panel b (203) are magnesium alloy panels, and the sandwich panel a (202) and the sandwich panel b (204) are carbon fiber reinforced resin composite panels, and the panels and the sandwich panels are bonded by resin glue to form a complete structure; The carbon fiber reinforced resin composite plate is formed by hot pressing an indocalamus cellulose modified epoxy resin (101) and a carbon fiber cloth (102); The first metal laminate (1) and the second metal laminate (111) are externally provided with an edge layer (2), and both side outer walls of the edge layer (2) are provided with a splicing strip (3); The side walls of the splicing strips (3) on both sides are provided with arc-shaped holes (8), and arc-shaped insertion rods (9) are inserted into the arc-shaped holes (8); The upper side walls of the splicing strips (3) on both sides are provided with countersunk grooves (13), and the countersunk grooves (13) are connected to the arc-shaped holes (8); A limiting cap (12) is mounted in the countersunk groove (13), a screw barrel (15) is mounted at the lower end of the limiting cap (12), and the screw barrel (15) is sleeved on the outside of the arc-shaped insertion rod (9); The outer portion of the screw barrel (15) is provided with a rubber pad a (11) and a rubber pad b (14) at the lower end of the limiting cap (12); The cellulose of indigo leaf is added to 50-70 ml of acetone solution and ultrasonically dispersed for 30-40 minutes. The dispersed cellulose of indigo leaf / acetone solution and epoxy resin are then ultrasonically stirred for 45-60 minutes to fully mix. The mixture is placed in an oven at 70-80°C to dry the acetone to obtain a cellulose of indigo leaf / epoxy resin mixed solution. Subsequently, a curing agent is added at a mass ratio of epoxy resin to curing agent of 3:1 and ultrasonically stirred for 30-40 minutes to obtain an indigo leaf cellulose modified epoxy resin. The epoxy resin modified with indigo cellulose was dip-coated on a unidirectional tape of T300 carbon fiber cloth, and four layers were laid in ascending order from 10% to 25% according to the mass fraction of indigo cellulose. The bottom layer was an epoxy resin with a mass fraction of 10% of indigo cellulose, and the top layer was an epoxy resin with a mass fraction of 25% of indigo cellulose. Then, the gradient order was changed every four layers in a symmetrical manner, and a total of 16 layers of carbon fiber cloth dipped in indigo cellulose modified epoxy resin were obtained. They were placed in a mold in the order of panel a-sandwich panel a-panel b-sandwich panel b-panel c and allowed to stand for 1 hour. Panels a, b and c were magnesium alloy plates, and then cured at 160-180°C and 1-3MPa for 3-4 hours to obtain a gradient structure carbon fiber metal laminate.

2. The natural cellulose modified carbon fiber metal laminate according to claim 1, characterized in that: A rubber block (10) is installed on the side wall of the rubber pad a (11) facing the rubber pad b (14), and the outer diameters of the rubber pad a (11) and the rubber pad b (14) are both larger than the inner diameter of the arc-shaped hole (8).

3. The natural cellulose modified carbon fiber metal laminate according to claim 2, characterized in that: The inner wall of the screw barrel (15) is provided with an internal thread, and the outer wall of the end of the arc-shaped insertion rod (9) is provided with an external thread (16), and the internal thread and the external thread (16) are matched.

4. The natural cellulose modified carbon fiber metal laminate according to claim 3, characterized in that: The side walls of the splicing strips (3) on both sides are provided with slots (4), and the edging layer (2) is snapped into the slots (4).

5. The natural cellulose modified carbon fiber metal laminate according to claim 4, characterized in that: Hook seats (5) are installed on the outer walls of the splicing strips (3) on both sides, and a rotation cavity (6) is opened on the side wall of the hook seat (5), and a hook (7) is clamped in the rotation cavity (6).

6. A method for preparing a natural cellulose modified carbon fiber metal laminate, for preparing a natural cellulose modified carbon fiber metal laminate according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1 material preparation, S2 material preparation, S3 plate laying and S4 plate synthesis; Step S1 Material preparation design The following steps are included: S11: Material preparation. The carbon fiber reinforced resin composite panels of sandwich panels a and b are modified carbon fiber composite materials containing cellulose extracted from indigo leaves with a gradient mass fraction. S12: Material cutting: After designing in step S11, panel a and panel b are cut by a shearing machine; Step S2: Material preparation includes the following steps: S21: Material processing, the indigo leaf cellulose is prepared by drying fresh indigo leaves for 30 days, crushing and screening, chemically treating, washing and drying, etc.; Fresh indigo leaves are dried for 30 days, crushed in a grinder for 10-30 minutes, and then sieved with a sieve. The crushed indigo leaves are then ball-milled for 40-60 minutes using a ball mill; the treated indigo leaf fine powder is soaked in a 5wt.% NaOH solution for 4-5 hours; after soaking, the indigo leaf fine powder is repeatedly washed with clean water, and then placed in an oven and dried at 90-100°C; after drying, the powder is sieved again to obtain indigo leaf fiber powder; Step S3 of adding additional plates includes the following steps: S31: Hot pressing molding, carbon fiber reinforced resin composite plate is prepared by hot pressing molding, and the lamination method is unidirectional laying of carbon fiber cloth coated with indocalamus cellulose modified epoxy resin, with a total of 16 layers; S32: Panel synthesis: Place the panels in the mold in the order of panel a-sandwich panel a-panel b-sandwich panel b-panel c and let them stand for 1 hour. Then put the whole into a hot press and press it. Curing treatment is carried out at 160-180℃ and 1-3 MPa for 3-4 hours to obtain a natural cellulose modified carbon fiber metal laminate.

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