Release cloth, composite material and preparation method

Abstract

The present invention provides a release cloth, a composite material and a preparation method, belonging to the technical field of composite materials. The release cloth includes: a support substrate; and a magnetic fiber array that pierces into the interior of the support substrate in an upright state, and at least part of the magnetic fibers in the magnetic fiber array are exposed outside the support substrate; wherein, the release cloth is used to be placed between a mold and a composite material to prevent the composite material from adhering to the mold after curing and forming. When the release cloth is separated from the composite material after the composite material is cured and formed, the magnetic fiber array detaches from the interior of the support substrate and remains inside the composite material, and the mechanical properties of the composite material are improved through the magnetic fiber array.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to a release cloth, a composite material and a preparation method thereof. Background Art

[0002] A composite material is composed of two or more different materials combined together, and these materials complement each other in performance to achieve properties that are difficult to achieve with a single material. The advantages of composite materials include: light weight, high strength, corrosion resistance, fatigue resistance, designability, etc., and they are widely used in many modern industrial technology fields such as aerospace, military, transportation, and construction. During the use process of composite materials in the above industrial technology fields, most different composite material components adopt bonding or mixing connection methods when forming the composite material. After the composite material components are cured and formed, the surface is covered by a resin layer, so it is relatively smooth and flat. When performing secondary bonding of different composite material components, the bonding strength of the resin bonding surface is weaker than the strength of the composite material component body, and it is easy to cause debonding failure of the bonding surface.

[0003] Currently, the commonly used treatment methods are to perform secondary treatment on the surface of the cured and formed composite material components through technical means such as sandblasting, grinding, plasma treatment, laser etching, etc. to improve the bonding strength of the bonding surface. However, sandblasting and grinding treatments in the above treatment methods often easily cause different degrees of damage to the composite material component body; plasma treatment or laser etching treatment has high requirements for equipment and is not easy to be applied on an industrial scale. Therefore, although the above technical means can improve the mechanical properties of composite materials to a certain extent, there are additional treatment costs, equipment costs, etc., and it is difficult to be promoted and applied in various different scenarios.

[0004] In summary, there is currently a lack of a convenient, efficient and highly universal technical solution to improve the secondary bonding strength of composite materials. Summary of the Invention

[0005] In view of the above technical problems, the present invention provides a release cloth, a composite material and a preparation method thereof, in order to at least partially solve the above technical problems, and the specific technical solutions provided by the present invention are as follows.

[0006] As a first aspect of the present invention, a release cloth is provided, including: a support substrate; and a magnetic fiber array, which penetrates into the support substrate in an upright state, and at least part of the magnetic fibers in the magnetic fiber array are exposed outside the support substrate; wherein, the release cloth is used to be placed between the mold and the composite material to prevent the composite material from adhering to the mold after curing and forming. When the release cloth is separated from the composite material after the composite material is cured and formed, the magnetic fiber array detaches from the inside of the support substrate and remains inside the composite material, and the mechanical properties of the composite material are improved through the magnetic fiber array.

[0007] As a second aspect of the present invention, a method for preparing a release cloth is provided, including: impregnating a support substrate with a rubber resin solution to obtain a pre-impregnated support substrate; placing the pre-impregnated support substrate in a magnetic field and uniformly dropping magnetic fibers from above the pre-impregnated support substrate, and under the action of the magnetic field and gravity, the magnetic fibers penetrate into the support substrate in a standing state to form a magnetic fiber array, and at least part of the magnetic fibers are exposed outside the support substrate, and then heating and curing to obtain the release cloth.

[0008] As a third aspect of the present invention, a composite material is provided, including: a first base material, in which a magnetic fiber array penetrates, and at least part of the magnetic fibers in the magnetic fiber array are exposed outside the first base material; and a second base material, which is bonded to the first base material by a resin adhesive, and the magnetic fiber array and the resin adhesive form a pinning effect; wherein, the magnetic fiber array is obtained by using the above-mentioned release cloth.

[0009] As a fourth aspect of the present invention, a method for preparing a composite material is provided, including: placing the release cloth in a mold; pouring a prepreg into the mold where the release cloth is placed; curing and molding the prepreg to obtain a first base material; separating the support substrate of the release cloth from the first base material, and the magnetic fiber array detaches from the support substrate and remains in the first base material; bonding the second base material to the first base material loaded with the magnetic fiber array by a resin adhesive and curing to obtain the composite material.

[0010] Based on the above technical solutions, at least one of the following beneficial effects exists in the release cloth, composite material and preparation method provided by the present invention.

[0011] (1) In the embodiments of the present invention, a release cloth loaded with magnetic fibers is provided. This release cloth can play a role in the curing and molding process of the composite material, effectively avoiding adhesion between the composite material and the mold during the curing and molding process. After the composite material is cured and molded, the magnetic fibers exposed on the surface of the release cloth are fixed inside the composite material. When separating the release cloth, the support substrate of the release cloth is removed, and the magnetic fibers in the release cloth remain inside the composite material. When the composite material is adhesively bonded for the second time, the mechanical properties of the bonding part during the second adhesive bonding of the composite material are improved by the magnetic fibers. At the same time, since the magnetic fibers penetrate into the composite material, the mechanical properties of the composite material itself can also be improved. The release cloth provided by the present invention can be used in the curing and molding processes of various composite materials, has no special requirements for the curing and molding process, does not cause surface damage to the composite material, and has good interlayer shear performance and high peel strength after the second adhesive bonding.

[0012] (2) In the embodiments of the present invention, the support substrate is first infiltrated with a rubber resin solution, and then magnetic fibers are distributed on the surface of the support substrate in an upright state to form a magnetic fiber array. Under the action of a magnetic field and gravity, the magnetic fibers pass through but do not penetrate the inside of the support substrate. After curing, the magnetic fibers are stably fixed inside the support substrate by the rubber resin, and at the same time, part of the magnetic fibers are exposed outside the support substrate. The preparation method of the release cloth provided by the present invention can achieve high-efficiency continuous preparation of the release cloth, which is convenient for industrial production.

[0013] (3) In the embodiments of the present invention, the above-mentioned release cloth is placed in a mold, and then the prepreg is cured and formed to obtain a first base material. When separating the release cloth, the magnetic fiber array in the release cloth is separated from the support substrate and remains inside the first base material. The second base material is bonded to the first base material loaded with the magnetic fiber array by a resin adhesive and cured to obtain a composite material. When the first base material and the second base material are combined, through the interaction between the magnetic fibers and the resin adhesive, the interfacial bonding force in the composite material is enhanced, so that the overall mechanical properties of the composite material are significantly improved, and the anti-tensile and anti-shear abilities are enhanced, meeting the requirements of more complex working conditions. Description of the Drawings

[0014] Figure 1 Schematic diagram of the continuous release cloth preparation process in Embodiment 1 of the present invention;

[0015] Figure 2 Scanning electron microscope (SEM) image of the release cloth in Embodiment 1 of the present invention;

[0016] Figure 3 Scanning electron microscope (SEM) image of stainless steel fibers exposed on the surface of the composite laminate in Embodiment 1 of the present invention;

[0017] Figure 4 Comparison chart of the I-type interlaminar fracture test load-displacement curves of different composite laminates in Embodiment 1 of the present invention.

[0018] Explanation of the reference numerals:

[0019] 01-1 Release cloth roller, 01-2 Dry release cloth, 01-3 First guide roller, 01-4 Silicone rubber resin solution, 01-5 Second guide roller, 01-6 Glue spreading roller, 01-7 Third guide roller, 01-8 Fourth guide roller, 01-9 Fifth guide roller, 01-10 Sixth guide roller, 01-11 Conveyor belt, 01-12 Rewinding roller;

[0020] 02-1 Vibration sieve, 02-2 Vibration motor;

[0021] 03-1 Stainless steel fibers, 03-2 stainless steel fibers in a vertical state, 03-3 stainless steel fibers partially inserted into the silicone rubber layer, 03-4 firmly fixed stainless steel fibers;

[0022] 04-1 First magnet, 04-2 Second magnet;

[0023] 05-1 Heating power supply, 05-2 First wire, 05-3 Second wire, 05-4 Heating pad, 05-5 Thermocouple;

[0024] 11-1 Stainless steel fibers, 11-2 Nylon mesh, 11-3 Silicone rubber layer;

[0025] 12-1 Stainless steel fibers, 12-2 Surface resin layer of the composite laminate. Detailed implementation manners

[0026] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0027] To improve the secondary bonding strength of the composite material and solve the problem of low interfacial fracture energy after the secondary bonding of the composite material. The present invention provides a release cloth composed of a support substrate and a magnetic fiber array, which can be used during the curing and molding process of the composite material, and the magnetic fiber array is left inside the composite material, while part of the magnetic fibers are exposed outside the composite material, and the mechanical properties of the bonding part during the secondary bonding of the composite material are improved through the magnetic fibers.

[0028] As the first aspect of the present invention, a release cloth is provided, including: a support substrate; and a magnetic fiber array, which penetrates into the interior of the support substrate in a vertical state, and at least part of the magnetic fibers in the magnetic fiber array are exposed outside the support substrate; wherein, the release cloth is used to be placed between the mold and the composite material to prevent the composite material from adhering to the mold after curing and molding. When the release cloth is separated from the composite material after the composite material is cured and molded, the magnetic fiber array detaches from the interior of the support substrate and remains inside the composite material, and the mechanical properties of the composite material are improved through the magnetic fiber array.

[0029] In an embodiment of the present invention, the present invention provides a release cloth loaded with magnetic fibers. This release cloth can play a role in the curing and molding process of composite materials, effectively preventing adhesion between the composite material and the mold during the curing and molding process. After the composite material is cured and molded, the magnetic fibers exposed on the surface of the release cloth are fixed inside the composite material. When separating the release cloth, the supporting substrate of the release cloth is removed, while the magnetic fibers in the release cloth remain inside the composite material. When the composite material is adhesively bonded for the second time, the mechanical properties of the bonding part during the second adhesive bonding of the composite material are improved through the magnetic fibers. At the same time, since the magnetic fibers penetrate into the composite material, the mechanical properties of the composite material body can also be improved. The release cloth provided by the present invention can be used in the curing and molding process of various composite materials, has no special requirements for the curing and molding process, does not cause surface damage to the composite material, and has good interlaminar shear performance and high peel strength after the second adhesive bonding.

[0030] According to an embodiment of the present invention, the loading amount of magnetic fibers on the supporting substrate is 10 - 100 fibers / cm 2 , for example, it can be 10 fibers / cm 2 , 30 fibers / cm 2 , 50 fibers / cm 2 , 80 fibers / cm 2 , 100 fibers / cm 2 . The distribution density of the magnetic fibers is determined according to the material type and density of the actually used magnetic fibers. Since there are significant differences among different types of magnetic fibers, the number of fibers per unit area is used as the distribution density counting method. At a lower loading amount, the pinning points of the magnetic fibers are relatively sparse, mainly inhibiting cracks and small deformations at the microscale. As the loading amount increases, on the one hand, more magnetic fibers provide more pinning points, strengthening the ability to hinder crack propagation, and on the other hand, the interaction between the magnetic fibers increases, forming a cooperative pinning effect similar to a "fiber cluster".

[0031] According to an embodiment of the present invention, the magnetic fibers are bonded to the supporting substrate through a rubber resin, and the rubber resin includes any one of nitrile rubber, hydrogenated nitrile rubber, fluororubber, silicone rubber, ethylene propylene rubber, fluorosilicone rubber, and acrylate rubber. Considering that the resin of the release cloth ultimately needs to be easily separated from the surface of the composite material prepared from thermosetting or thermoplastic resin materials, a rubber resin is selected, preferably silicone rubber resin with a lower cost, and the viscosity of the silicone rubber resin is not greater than 8000. If the viscosity is too high, it is difficult for the magnetic fibers to fall to the bottom of the rubber resin by gravity and magnetic field effects in a short time.

[0032] According to an embodiment of the present invention, the pore diameter of the support substrate is 50 μm - 1 mm, and for example, it can be 50 μm, 200 μm, 500 μm, 800 μm, 1 mm. The thickness of the support substrate is 0.05 - 2.5 mm, and for example, it can be 0.05 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm. The diameter of the magnetic fiber is 5 - 300 μm, and for example, it can be 5 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm. The length of the magnetic fiber is 0.2 - 5 mm, and for example, it can be 0.2 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm. The length of the magnetic fiber exposed outside the support substrate is 0.15 - 2.5 mm, and for example, it can be 0.15 mm, 0.5 mm, 1 mm, 2 mm, 2.5 mm. The pore diameter of the support substrate is larger than the diameter of the magnetic fiber, so that the magnetic fiber can fall into the holes of the support substrate under the action of gravity and magnetic field. At this time, the magnetic fiber is fixed by rubber resin, so that the magnetic fiber is stably attached to the support substrate. For example, when the pore diameter of the support substrate is 50 μm, the diameter of the magnetic fiber is 5 - 10 μm; when the pore diameter of the support substrate is 500 μm, the diameter of the magnetic fiber is 5 - 100 μm. In the subsequent process of preparing the composite material, the magnetic fiber exposed outside the support substrate remains inside the composite material. Since the magnetic fiber falls to the bottom of the holes of the support substrate under the action of gravity and magnetic field, and considering the thickness of the rubber resin at the same time, the length of the magnetic fiber is controlled to be about two to three times the thickness of the support substrate, so as to control the lengths of the magnetic fiber inside and outside the support substrate to be consistent. For example, when the thickness of the support substrate is 0.5 mm, the length of the magnetic fiber is 1 - 1.5 mm; when the thickness of the support substrate is 2 mm, the length of the magnetic fiber is 4 - 4.5 mm.

[0033] According to an embodiment of the present invention, the supporting substrate includes any one of a metal wire mesh and a non-metal wire mesh; the metal wire mesh includes any one of a stainless steel wire mesh, an aluminum mesh, and a copper mesh; the non-metal wire mesh includes any one of a nylon mesh, a polyester mesh, a polypropylene mesh, a polyethylene mesh, and a polyethylene fiber mesh. The supporting substrate provides a stable support for the magnetic fibers and can be reused. The magnetic fibers include at least one of stainless steel fibers, nickel-plated fibers, and fibers coated with a layer of iron tetroxide; the nickel-plated fibers include at least one of nickel-plated carbon fibers, nickel-plated glass fibers, nickel-plated basalt fibers, nickel-plated aramid fibers, nickel-plated liquid crystal fibers, and nickel-plated polyamide fibers; the fibers coated with a layer of iron tetroxide include at least one of carbon fibers coated with iron tetroxide, glass fibers coated with iron tetroxide, basalt fibers coated with iron tetroxide, aramid fibers coated with iron tetroxide, liquid crystal fibers coated with iron tetroxide, and polyamide fibers coated with iron tetroxide. Since the magnetic fibers remain inside the composite material subsequently, fibers made of the same or similar materials as the composite material can be selected for nickel plating or coating with iron tetroxide to obtain magnetic fibers, which can meet the actual application requirements of the composite material and have magnetic properties, and remain upright during the preparation process of the release cloth.

[0034] As a second aspect of the present invention, a method for preparing a release cloth is provided, including: impregnating a supporting substrate with a rubber resin solution to obtain a pre-impregnated supporting substrate; placing the pre-impregnated supporting substrate in a magnetic field and uniformly dropping magnetic fibers from above the pre-impregnated supporting substrate. Under the action of the magnetic field and gravity, the magnetic fibers penetrate into the supporting substrate in an upright state to form a magnetic fiber array, and at least part of the magnetic fibers are exposed outside the supporting substrate. Then, heating and curing are performed to obtain the release cloth.

[0035] In the embodiment of the present invention, first, the supporting substrate is infiltrated with the rubber resin solution, and then the magnetic fibers are distributed on the surface of the supporting substrate in an upright state to form a magnetic fiber array. The magnetic fibers penetrate but do not penetrate out of the inside of the supporting substrate under the action of the magnetic field and gravity. After curing, the magnetic fibers are stably fixed inside the supporting substrate by the rubber resin, and at least part of the magnetic fibers are exposed outside the supporting substrate. The method for preparing the release cloth provided by the present invention can achieve high-efficiency continuous preparation of the release cloth, which is convenient for industrial production.

[0036] As a third aspect of the present invention, a composite material is provided, including: a first base material, with a magnetic fiber array penetrating into the first base material, and at least part of the magnetic fibers in the magnetic fiber array are exposed outside the first base material; and a second base material, adhesively bonded to the first base material through a resin adhesive, and the magnetic fiber array and the resin adhesive form a pinning effect; wherein, the magnetic fiber array is obtained by using the above-mentioned release cloth.

[0037] In an embodiment of the present invention, the above-mentioned release cloth is used to prepare a first base material, and magnetic fiber arrays are inserted into the first base material, and a part of the magnetic fibers in the magnetic fiber arrays are exposed outside the first base material. The surface of the first base material distributed with the magnetic fiber arrays is bonded to the second base material through a resin adhesive. Through the pinning effect formed by the magnetic fiber arrays and the resin adhesive, the initiation and propagation of cracks in the resin adhesive are hindered, and the mechanical properties of the composite material are improved.

[0038] According to an embodiment of the present invention, the length of the magnetic fibers exposed outside the first base material is 0.05 - 2.5 mm, and for example, it can be 0.05 mm, 0.5 mm, 1 mm, 2 mm, 2.5 mm. When preparing a multi-layer composite material, the exposed magnetic fibers can "pin" adjacent material layers together like "nails". A shorter exposed length can ensure a certain pinning effect while not protruding excessively, avoiding affecting the surface flatness of the composite material. A longer exposed length can provide a deeper pinning effect in cases where a stronger bonding force is required, such as when manufacturing aerospace materials or high-performance sports equipment with extremely high requirements for interlayer bonding, ensuring that each layer can work together and withstand greater external forces.

[0039] According to an embodiment of the present invention, the resin adhesive includes at least one of thermosetting resins and thermoplastic resins; the thermosetting resins include at least one of epoxy resins, polyurethanes, unsaturated polyesters, and phenolic resins; the thermoplastic resins include at least one of polyvinyl alcohol, polyvinyl butyral, polyvinyl acetate, polyester, polyacrylate, rosin-modified alkyd resin, polyvinyl chloride, chlorinated polypropylene, and alcohol-soluble polyamide. When the first base material and the second base material are bonded through the resin adhesive, the magnetic fibers exposed outside the first base material form a pinning effect with the resin adhesive to hinder the initiation and propagation of cracks in the resin adhesive and improve the mechanical properties of the composite material.

[0040] In an embodiment of the present invention, when the second base material is also prepared through the above-mentioned release cloth, the surface of the second base material loaded with magnetic fibers is bonded to the surface of the first base material loaded with magnetic fibers through a resin adhesive. At this time, the magnetic fibers exposed outside the first base material and the magnetic fibers exposed outside the second base material both form a pinning effect with the resin adhesive, further improving the mechanical properties of the composite material.

[0041] As the fourth aspect of the present invention, a method for preparing a composite material is provided, including: disposing a release cloth in a mold; pouring a prepreg into the mold with the release cloth placed therein; curing and molding the prepreg to obtain a first base material; separating the support substrate of the release cloth from the first base material, and the magnetic fiber array detaches from inside the support substrate and remains in the first base material; bonding and curing a second base material to the first base material loaded with the magnetic fiber array through a resin adhesive to obtain the composite material.

[0042] In an embodiment of the present invention, the above-mentioned release cloth is disposed in the mold, and then the prepreg is cured and molded to obtain the first base material. When separating the release cloth, the magnetic fiber array in the release cloth detaches from the support substrate and remains inside the first base material. The second base material is bonded and cured to the first base material loaded with the magnetic fiber array through a resin adhesive to obtain the composite material. When the first base material and the second base material are combined, through the interaction between the magnetic fiber and the resin adhesive, the interfacial bonding force in the composite material is enhanced, so that the overall mechanical properties of the composite material are significantly improved, and the tensile and shear resistance capabilities are enhanced, meeting the requirements of more complex working conditions.

[0043] The present invention will be further described below through examples and related test experiments. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. Moreover, without conflict, the details in the following embodiments can be combined arbitrarily into other feasible embodiments. All instruments, consumables, reagents, etc. in the following embodiments can be obtained from commercial channels without special instructions.

[0044] Example 1

[0045] In this Example 1, a release cloth was prepared by the following method, and the prepared release cloth was used to prepare the composite material.

[0046] In this Example 1, the support substrate is selected as a nylon mesh with a pore size of 0.2 0.2 mm and a thickness of 200 μm. The magnetic fiber is a stainless steel fiber with a length of 1000 μm and a diameter of 40 μm. The adhesive resin solution is a silicone rubber resin solution, and a certain proportion of ethanol solvent is incorporated to dilute the solution.

[0047] Figure 1 It is a schematic diagram of the continuous release cloth preparation process in Example 1 of the present invention.

[0048] As Figure 1 shown, the release cloth was prepared by the following method.

[0049] Take out the 80-mesh nylon mesh belt 01-2 from the release cloth roller 01-1, pass it through the first guide roller 01-3, silicone rubber resin solution 01-4, second guide roller 01-5, coating roller 01-6, and third guide roller 01-7. The nylon mesh belt impregnated with the silicone rubber resin solution is transported forward by the conveyor belt 01-11. The conveyor belt 01-11 realizes periodic operation through the third guide roller 01-7, fourth guide roller 01-8, fifth guide roller 01-9, and sixth guide roller 01-10; When the nylon mesh belt reaches below the vibrating screen 02-1, vibration motors 02-2 are installed on both sides of the vibrating screen 02-1. After starting the vibration motors 02-2, the stainless steel fibers 03-1 fall from the vibrating screen 02-1 and are oriented along the magnetic force lines in the air during the falling process, and the stainless steel fibers 03-2 in a vertical state are distributed on the silicone rubber layer on the surface of the nylon mesh belt. Under the action of gravity and magnetic attraction, the stainless steel fibers 03-2 are inserted into the silicone rubber layer and directly penetrate to the bottom of the silicone rubber layer, obtaining the stainless steel fibers 03-3 partially inserted into the silicone rubber layer. The nylon mesh belt moves forward under the traction of the winding roller 01-12 and reaches the middle of the first magnet 04-1 and the second magnet 04-2. Under the action of the highly oriented magnetic field established between the two magnets, the stainless steel fibers obtain a higher uprightness; Turn on the heating power supply 05-1, heat the heating pad 05-4 through the first wire 05-2, and connect it to the thermocouple 05-5 through the second wire 05-3. The thermocouple 05-5 is placed inside the heating pad 05-4 to sense the temperature signal of the heating pad 05-4 in real time, and the signal is fed back to the heating power supply 05-1, thereby realizing the regulation of the temperature of the heating pad 05-4. The silicone rubber resin in the nylon mesh belt is quickly cured after heating, and the stable and fixed stainless steel fibers 03-4 are obtained after the resin is cured. After the release cloth is dried, it is wound into a roll by the winding roller 01-12.

[0050] Figure 2 It is the scanning electron microscope (SEM) image of the release cloth in Embodiment 1 of the present invention.

[0051] From Figure 2 It can be seen that the stainless steel fibers are stably and uprightly distributed in the nylon cloth wrapped with silicone rubber.

[0052] Further, the above-mentioned release cloth is used in the vacuum bag hot pressing forming process of composite materials. Unidirectional carbon fiber prepreg with a thickness of 0.15 mm is used. After laying 10 layers of prepreg, a release cloth with vertically oriented stainless steel fibers is laid on the surface. The composite material laminate with a thickness of 1.5 mm is obtained by hot pressing and curing. The release cloth is torn off, and the stainless steel fibers in the release cloth are detached from the nylon cloth wrapped with silicone rubber and remain in the composite material laminate. After coating the resin adhesive on the side with stainless steel fibers, two laminates are pressed together. After the resin is cured, the peel load of the composite material laminate after secondary bonding is tested according to the ASTM D5528 double cantilever beam type I interlaminar fracture toughness test method.

[0053] Figure 3 This is a scanning electron microscope (SEM) image of the stainless steel fibers exposed on the surface of the composite material laminate in Example 1 of the present invention.

[0054] From Figure 3 it can be seen that the stainless steel fibers have been completely transferred from the surface of the release cloth to the surface of the composite material laminate and are partially exposed outside the composite material laminate.

[0055] Figure 4 This is a comparison chart of the load-displacement curves of the type I interlaminar fracture tests of different composite material laminates in Example 1 of the present invention. Among them, in addition to the composite material laminate prepared by using the release cloth loaded with stainless steel fibers, a composite material laminate without using the release cloth and a composite material laminate without using the release cloth but sanded and then bonded are also prepared.

[0056] From Figure 4 it can be seen that sanding the surface of the composite material laminate only slightly improves the interlaminar fracture performance of the composite material laminate, but the interlaminar fracture toughness of the composite material laminate with the release cloth is significantly improved. Integrating the area of three typical curves, the work done in the peeling process of the untreated composite material laminate is 1.25 J, the work done in the peeling process of the composite material laminate obtained by sanding is 1.44 J, and the work done in the peeling process of the composite material laminate obtained by the release cloth is 2.27 J. The results show that the improvement amplitude of the peeling work of the composite material laminate obtained by the release cloth prepared by the present invention is 81.6% compared with the untreated composite material laminate.

[0057] The specific embodiments described above have further detailed the purpose, technical solution and beneficial effects of the present invention. It should be understood that the above description is only specific embodiments of the present invention and is not used to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A release cloth comprising: a supporting substrate; as well as a magnetic fiber array, which is upright and penetrates into the interior of the support substrate, and the magnetic fibers in the magnetic fiber array are at least partially exposed outside the support substrate; The release cloth is placed between the mold and the composite material to prevent the composite material from adhering to the mold after solidification. When the release cloth is separated from the composite material after solidification, the magnetic fiber array detaches from the inside of the supporting substrate and remains inside the composite material, thereby improving the mechanical properties of the composite material. The pore size of the support substrate is 50 μm-1 mm, and the thickness of the support substrate is 0.05 mm-2.5 mm; The diameter of the magnetic fiber is 5 μm-300 μm, and the length of the magnetic fiber is 0.2 mm-5 mm; The length of the magnetic fiber exposed outside the supporting substrate is 0.15 mm to 2.5 mm; The magnetic fibers are bonded to the supporting substrate via a rubber resin; The rubber resin includes any one of nitrile rubber, hydrogenated nitrile rubber, fluororubber, silicone rubber, ethylene propylene rubber, fluorosilicone rubber, and acrylate rubber; The supporting substrate includes any one of a metal mesh and a non-metal mesh; The metal wire mesh includes any one of stainless steel wire mesh, aluminum mesh, and copper mesh; The non-metallic wire mesh includes any one of nylon mesh, polyester mesh, polypropylene mesh, polyethylene mesh, and polyethylene fiber mesh.

2. The release cloth according to claim 1, wherein The loading capacity of the magnetic fibers on the support substrate is 10-100 fibers / cm 2 .

3. The release cloth according to claim 2, wherein: The magnetic fiber includes at least one of stainless steel fiber, nickel-plated fiber, and fiber coated with a ferroferric oxide layer.

4. The release cloth according to claim 3, wherein The nickel-plated fiber includes at least one of nickel-plated carbon fiber, nickel-plated glass fiber, nickel-plated basalt fiber, nickel-plated aramid fiber, nickel-plated liquid crystal fiber, and nickel-plated nylon fiber; The fiber coated with the ferroferric oxide layer includes at least one of carbon fiber coated with ferroferric oxide, glass fiber coated with ferroferric oxide, basalt fiber coated with ferroferric oxide, aramid fiber coated with ferroferric oxide, liquid crystal fiber coated with ferroferric oxide, and nylon fiber coated with ferroferric oxide.

5. A method for preparing a release cloth according to any one of claims 1 to 4, comprising: impregnating the support substrate with a rubber resin solution to obtain a pre-impregnated support substrate; The prepreg support substrate is placed in a magnetic field and magnetic fibers are evenly dropped from above the prepreg support substrate. Under the action of the magnetic field and gravity, the magnetic fibers are upright and penetrate into the interior of the support substrate to form a magnetic fiber array. At the same time, the magnetic fibers are at least partially exposed outside the support substrate, heated and cured to obtain a release cloth.

6. A composite material comprising: A first base material, wherein a magnetic fiber array is inserted into the first base material, and the magnetic fibers in the magnetic fiber array are at least partially exposed outside the first base material; as well as The second base material is bonded to the first base material via a resin adhesive, and the magnetic fiber array and the resin adhesive form a pinning effect; Wherein, the magnetic fiber array is obtained using the release cloth according to any one of claims 1 to 4.

7. The composite material according to claim 6, wherein The length of the magnetic fiber exposed outside the first base material is 0.05mm-2.5mm; The resin glue includes at least one of a thermosetting resin and a thermoplastic resin.

8. The composite material according to claim 7, wherein The thermosetting resin includes at least one of epoxy resin, polyurethane, unsaturated polyester and phenolic resin; The thermoplastic resin includes at least one of polyvinyl alcohol, polyvinyl butyral, polyvinyl acetate, polyester, polyacrylate, rosin-modified alkyd resin, polyvinyl chloride, chlorinated polypropylene, and alcohol-soluble polyamide.

9. A method for preparing the composite material according to any one of claims 6 to 8, comprising: placing the demoulding arrangement in the mold; pouring the prepreg into the mold on which the release cloth is placed; Curing and molding the prepreg to obtain a first base material; separating the support substrate of the release cloth from the first base material, so that the magnetic fiber array detaches from the interior of the support substrate and remains in the first base material; The second base material and the first base material loaded with the magnetic fiber array are bonded and cured by resin glue to obtain a composite material.

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