Plant fiber composite material, preparation method and application thereof, and printed circuit board

Abstract

The invention belongs to the technical field of printed circuit boards, and particularly relates to a plant fiber composite material, a preparation method and application thereof and a printed circuit board. The plant fiber composite material provided by the invention is prepared from the following raw materials: a resin system and plant fibers, the resin system comprises resin and a curing agent; the resin comprises controllable hydrolysis epoxy resin, polyvinyl alcohol, sulfonated unsaturated polyester resin, esterified polyurethane resin or esterified phenolic resin; the plant fibers account for 5-85% of the preparation raw materials in percentage by mass. The plant fiber composite material provided by the invention takes a controllable hydrolysis resin system and biodegradable plant fibers as raw materials, has degradability and good mechanical properties, is used for preparing a printed circuit board, is convenient for recovery of noble metals, and can reduce environmental pollution.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of printed circuit boards, and particularly relates to a plant fiber composite material, a preparation method and application thereof, and a printed circuit board. BACKGROUND

[0002] With the rapid development of the Internet of Things technology, the demand for electronic components is gradually increasing. Printed circuit boards are important electronic components, are the support of electronic components, and are the carrier of electrical interconnection of electronic components. Printed circuit boards (PCB) are usually made of non-degradable epoxy resin and environmentally polluting glass fiber, and also contain precious metals such as gold, silver, palladium, etc. Electronic products usually have a relatively short service life, and glass fiber as a harmful substance can only be crushed, incinerated or landfilled after the circuit board is scrapped, resulting in a great waste of resources. The precious metals contained in electronic components are usually fixed on the circuit board in the form of small particles by means of welding, etc. This design meets the use requirements, but also significantly increases the technical difficulty and economic cost of recycling from waste electronic products. At the same time, the epoxy resin in the waste printed circuit board cannot be decomposed by the conventional biodegradation process, thus becoming a long-term environmental pollution source. Although glass fiber as a reinforcing material improves the mechanical and structural stability of the PCB, it is difficult to recycle. The non-degradability and non-recyclability of epoxy resin and glass fiber lead to serious environmental pollution in the process of electronic waste treatment, and the harmful substances contained therein may penetrate into the soil and water, causing long-term negative effects on the ecosystem. SUMMARY

[0003] Therefore, the present application provides a plant fiber composite material, a preparation method and application thereof, and a printed circuit board. The plant fiber composite material provided by the present application is prepared from a resin system (containing resin and curing agent) and biodegradable plant fiber, has stable mechanical properties and degradability, and can be used for preparing a printed circuit board substrate. When the plant fiber composite material is used for preparing a printed circuit board substrate, the substrate can be disassembled by hydrolysis, the difficulty of precious metal recovery is greatly reduced, and the environmental pollution problem of traditional glass fiber-epoxy resin substrates is avoided.

[0004] To solve the above technical problems, the present application provides a plant fiber composite material, and the preparation raw materials of the plant fiber composite material include a resin system and plant fiber. The resin system includes resin and a curing agent. The resin includes controllable hydrolysis epoxy resin, polyvinyl alcohol, sulfonated unsaturated polyester resin, esterified polyurethane resin or esterified phenolic resin. The mass percentage of the plant fiber in the preparation raw materials is 5-85%.

[0005] Preferably, the plant fiber comprises a hydrophobic modified plant fiber, and the resin system comprises a hydrophilic modified resin. The hydrophobic modified plant fiber and the hydrophilic modified resin cannot exist simultaneously.

[0006] Preferably, the preparation method of the hydrophobic modified plant fiber comprises the following steps: mixing plant fiber and a hydrophobic modification solution to modify, so as to obtain the hydrophobic modified plant fiber. The hydrophobic modification solution comprises a coupling agent solution or an alkaline solution. The coupling agent solution comprises a silane coupling agent solution or a titanate coupling agent solution. The alkaline solution comprises a sodium hydroxide solution, a potassium hydroxide solution or a calcium hydroxide solution.

[0007] Preferably, the preparation method of the hydrophilic modified resin comprises the following steps: mixing resin and a hydrophilic modifier to carry out a grafting reaction, so as to obtain the hydrophilic modified resin. The hydrophilic modifier comprises maleic anhydride, diethylenetriamine, isocyanate or epoxy-acrylate copolymer. The temperature of the grafting reaction is 40-60℃, and the time of the grafting reaction is 20-35min.

[0008] Preferably, the curing agent comprises an amine curing agent or an acid anhydride curing agent. The amine curing agent comprises ethylenediamine, hexanediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine or m-phenylenediamine. The acid anhydride curing agent comprises maleic anhydride or phthalic anhydride. The mass percentage content of the curing agent in the resin system is 10-60%.

[0009] Preferably, the resin system further comprises a filler. The filler comprises one or more of silica powder, quartz powder, aluminum powder, copper powder, ceramic particles, carbon black, zinc oxide, titanium oxide, polystyrene and polymethyl methacrylate.

[0010] The application further provides a preparation method of the plant fiber composite material. Mixing plant fiber and a resin system and then heat treating to obtain a prepreg. Stacking the prepreg and then forming to obtain the plant fiber composite material.

[0011] Preferably, the temperature of the heat treatment is 80-120℃, and the holding time of the heat treatment is 1-6h. The forming mode comprises hot pressing or hot assisted vacuum lamination. The temperature of the hot pressing is 120-200 DEG C; the pressure of the hot pressing is 3-10 MPa; and the holding time of the hot pressing is 15-60 min.

[0012] The application further provides application of the plant fiber composite material in preparation of a printed circuit board.

[0013] The application further provides a printed circuit board, which comprises a substrate, copper cladding, printed ink, solder resist, a shielding layer and a solder pad. The substrate is formed of the plant fiber composite material.

[0014] The application provides a plant fiber composite material, raw materials of the plant fiber composite material comprising a resin system and plant fibers; the resin system comprising resin and a curing agent; the resin comprising controllable hydrolysis epoxy resin, polyvinyl alcohol, sulfonated unsaturated polyester resin, esterified polyurethane resin or esterified phenolic resin; and the plant fibers accounting for 5-85% of the mass percentage of the raw materials. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A physical picture of the prepreg prepared in Example 1; Figure 2 A physical picture of the fiber composite material prepared in Example 1. DETAILED DESCRIPTION

[0016] The application provides a plant fiber composite material, raw materials of the plant fiber composite material comprising a resin system and plant fibers.

[0017] In the present application, the resin system comprises a resin and a curing agent; the resin can comprise a controllable hydrolysis epoxy resin, polyvinyl alcohol, sulfonated unsaturated polyester resin, esterified polyurethane resin or esterified phenolic resin. As a specific embodiment of the present application, the controllable hydrolysis epoxy resin can comprise NPEL or Hexion epoxy resin. As a specific embodiment of the present application, the NPEL can comprise NPEL-127E or NPEL-128G; the characteristic parameters of NPEL-127E can be: hydrolysis chlorine content ≤300ppm, epoxy equivalent weight 176~184g / eq, viscosity 8000~11000cps, tensile strength after curing ≥50MPa, hydrolysis half-life 30 days @ 60℃ water. As a specific embodiment of the present application, the characteristic parameters of NPEL-128G can be: tensile strength after curing ≥50MPa, hydrolysis half-life 35 days @ 60℃ water, hydrolysis chlorine content ≤150ppm, epoxy equivalent weight 184~190g / eq, viscosity 12000~15000cps. In the present application, both NPEL-127E and NPEL-128G have low hydrolysis chlorine, which are suitable for electronic packaging.

[0018] As a specific embodiment of the present application, the Hexion epoxy resin can comprise Epikote 828EL, Epikote 828LS or Epikote 828LVEL; the characteristic parameters of Epikote 828EL can be: tensile strength after curing ≥45MPa, hydrolysis half-life 20 days @ 60℃ water, hydrolysis chlorine content ≤150ppm, epoxy equivalent weight 186~190g / eq, viscosity 12500~14500cps; the characteristic parameters of Epikote 828LS can be: hydrolysis chlorine content ≤150ppm, epoxy equivalent weight 184-190g / eq, viscosity 12000-14000cps; the characteristic parameters of Epikote 828LVEL can be: hydrolysis chlorine content ≤150ppm, epoxy equivalent weight 182~187g / eq, viscosity 10000~12000cps.

[0019] As a specific embodiment of the present application, the curing agent can comprise an amine curing agent or an acid anhydride curing agent; the amine curing agent can comprise ethylenediamine, hexanediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine or m-phenylenediamine; the acid anhydride curing agent can comprise maleic anhydride or phthalic anhydride; the mass percentage content of the curing agent in the resin system can be 10~60%, and can also be 20~35%.

[0020] As a specific embodiment of the present application, the resin system can further comprise a filler; the filler can comprise one or more of silica powder, quartz powder, aluminum powder, copper powder, ceramic particles, carbon black, zinc oxide, titanium oxide, polystyrene, and polymethyl methacrylate. The present application can improve different properties of the plant fiber composite material by adding different fillers to the resin system, for example, silica powder, quartz powder, and ceramic particles can improve the hardness, wear resistance, and compressive strength of the fiber composite material; aluminum powder and copper powder can enhance the heat dissipation performance of the fiber composite material; carbon black, zinc oxide, and titanium oxide can improve the electrical conductivity and dielectric properties of the fiber composite material, which can be used for electromagnetic shielding materials; polystyrene and polymethyl methacrylate can increase the resin flowability and improve the resin's ability to penetrate the fiber.

[0021] As a specific embodiment of the present application, the plant fiber can comprise one or more of bamboo powder, wood powder, plant fiber felt, bamboo skin, wood skin, woven plant fiber yarn, woven bamboo filament, unidirectional plant fiber yarn, and unidirectional bamboo filament, and can specifically be bamboo powder, wood powder, plant fiber felt, bamboo skin, wood skin, woven plant fiber yarn, woven bamboo filament, unidirectional plant fiber yarn, or unidirectional bamboo filament.

[0022] As a specific embodiment of the present application, the mass percentage of the plant fiber in the preparation raw material can be 5-85%, and can specifically be 10%, 20%, 30%, 50%, 65%, 70%, or 85%.

[0023] As a specific embodiment of the present application, the plant fiber can comprise hydrophobic modified plant fiber, and the resin system can comprise hydrophilic modified resin; the hydrophobic modified plant fiber and the hydrophilic modified resin cannot exist simultaneously. The present application can improve the adhesion with the resin system by hydrophobic modification of the plant fiber; and can improve the adhesion with the plant fiber by hydrophilic modification of the resin.

[0024] As a specific embodiment of the present application, the preparation method of the hydrophobic modified plant fiber comprises the following steps: mixing the plant fiber and a hydrophobic modification solution to modify, to obtain the hydrophobic modified plant fiber. As a specific embodiment of the present application, before the mixing, the plant fiber can be washed, and then subjected to solid-liquid separation and drying in sequence. As a specific embodiment of the present application, the washing can comprise soaking the plant fiber in deionized water or ethanol for 10-30 min, and then ultrasonic cleaning for 10 min; the solid-liquid separation can be filtration; the drying temperature can be 60-80°C, and can specifically be 60°C, 65°C, 70°C, 75°C, or 80°C; the drying time can be 22-26 h, and can specifically be 24 h. The present application can remove impurities (dust, debris), grease, and water-soluble parts on the surface of the plant fiber by washing.

[0025] As a specific embodiment of the present application, the hydrophobic modification solution can include a coupling agent solution or a basic solution; the coupling agent solution can include a silane coupling agent solution or a titanate coupling agent solution; the basic solution can include a sodium hydroxide solution, a potassium hydroxide solution or a calcium hydroxide solution; the mass concentration of the basic solution can be 2-10%, and can also be 4-8%; the silane coupling agent solution can include KH550, KH560, KH570 or A-174; the titanate coupling agent solution can include titanium isopropyl triisostearate (TTS) or amino titanate (KR-55).

[0026] As a specific embodiment of the present application, when the hydrophobic modification solution is a basic solution, the method for mixing the plant fiber and the basic solution to perform modification can include the following steps: soaking the plant fiber in the basic solution, then washing with water, drying to obtain the hydrophobic modified plant fiber; the mass concentration of the basic solution can be 2-10%, and can also be 4-8%, the present application does not have special limitation on the amount of the basic solution, as long as it can immerse the plant fiber; the soaking temperature is 60-90℃, and the time is 3-8h. As a specific embodiment of the present application, the water washing is to immerse the plant fiber after soaking the alkali solution in water for ultrasonic cleaning; the water can be deionized water, the soaking time can be 8-12min, and can be specifically 10min; the ultrasonic cleaning time can be 8-12min, and can be specifically 10min; the drying temperature can be 58-62℃, and can be specifically 60℃, and the drying time can be 23-25h, and can be specifically 24h. The present application can remove the residual basic solution on the surface of the hydrophobic modified plant fiber through water washing, and can remove the moisture on the surface of the hydrophobic modified plant fiber through drying.

[0027] As a specific embodiment of the present application, when the hydrophobic modification solution is a silane coupling agent solution, the method for mixing the plant fiber and the silane coupling agent solution to perform modification can include the following steps: dissolving the silane coupling agent in an aqueous solution of ethanol, adjusting the pH value of the system to 4-5 to obtain a silane coupling agent solution; immersing the plant fiber in the silane coupling agent solution or spraying the silane coupling agent solution to the surface of the plant fiber to perform condensation reaction to obtain the hydrophobic modified plant fiber.

[0028] As a specific embodiment of the present application, the volume ratio of ethanol and water in the aqueous ethanol solution can be 8-10:1, and can specifically be 9:1; the pH adjusting agent for adjusting the pH of the system can be acetic acid, and the present application does not have a special limitation on the amount of acetic acid, as long as the desired pH value can be achieved. The present application can continue to stir for 25-30 min after adjusting the pH, and the stirring temperature can be room temperature, which can be 20-35℃, and can also be 25-30℃. The present application does not have a special requirement for the stirring speed, as long as the system is uniform. Adjusting the pH of the silane coupling agent solution to 4-5 is beneficial to the hydrolysis modification.

[0029] As a specific embodiment of the present application, the mass ratio of the plant fiber and the silane coupling agent can be 100:0.5-5, and can specifically be 100:0.5, 100:1.0, 100:2.0 or 100:5; the solid-liquid mass ratio of the plant fiber and the silane coupling agent solution can be 1:1-5, and can specifically be 1:3. When mixing the plant fiber and the silane coupling agent solution in the dipping mode, stirring can be accompanied, the stirring temperature can be room temperature, which can be 20-35℃, and can also be 25-30℃; the stirring time can be 1-2 h. The present application does not have a special requirement for the stirring speed, as long as the system is uniform. The present application can perform solid-liquid separation by filtration after stirring.

[0030] As a specific embodiment of the present application, the temperature of the condensation reaction can be 100-120℃, and can specifically be 100℃, 110℃ or 120℃; the time of the condensation reaction can be 1-2 h, and can specifically be 1 h, 1.5 h or 2 h. The present application can condense silane and hydroxyl in the plant fiber to form a covalent bond through the condensation reaction, so as to realize the hydrophobic modification of the plant fiber.

[0031] As a specific embodiment of the present application, when the hydrophobic modification solution is a titanate coupling agent solution, the method for modifying the plant fiber by mixing the plant fiber and the titanate coupling agent solution can include the following steps: dissolving the titanate coupling agent in anhydrous ethanol to obtain a titanate coupling agent solution; immersing the plant fiber in the titanate coupling agent solution or spraying the titanate coupling agent solution to the surface of the plant fiber to perform esterification reaction, so as to obtain the hydrophobic modified plant fiber.

[0032] As a specific embodiment of the present application, the mass ratio of the plant fiber and the titanate coupling agent can be 100:0.5-2, and can specifically be 100:0.5, 100:1, 100:1.50 or 100:2; the volume ratio of the titanate coupling agent and anhydrous ethanol can be 1:5-10, and can specifically be 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10; the stirring can be carried out at room temperature, and the room temperature can be 20-35℃, and can also be 25-30℃; the stirring time can be 8-10 min. The present application does not have special requirements for the stirring speed, as long as it can be completely dissolved.

[0033] As a specific embodiment of the present application, the solid-liquid ratio of the plant fiber and the titanate coupling agent solution can be 1:1-5, and can specifically be 1:1, 1:2, 1:3, 1:4 or 1:5. When the plant fiber and the titanate coupling agent solution are mixed in the form of immersion, stirring can be accompanied, the stirring temperature can be room temperature, and the room temperature can be 20-35℃, and can also be 25-30℃; the stirring time can be 30-60 min, and can specifically be 30 min, 40 min, 50 min or 60 min. The present application does not have special requirements for the stirring speed, as long as it can make the system uniform. After stirring, the present application can be separated by filtration. When the plant fiber and the titanate coupling agent solution are mixed in the form of spraying, stirring can be accompanied, and the mass ratio of the sprayed titanate coupling agent solution and the fabric fiber can be 5-10:100.

[0034] As a specific embodiment of the present application, the temperature of the esterification reaction can be 80-100℃, and can specifically be 80℃, 90℃ or 100℃; the time of the esterification reaction can be 1-2 h, and can specifically be 1 h, 1.5 h or 2 h. After the esterification reaction, the present application can make the titanate coupling agent react with the hydroxyl group in the plant fiber to form a covalent bond, so as to realize the hydrophobic modification of the plant fiber.

[0035] The present application can seal the hydrophobic plant fiber in an aluminum foil bag and store it in a dry environment; the relative humidity of the dry environment can be <40%.

[0036] As a specific embodiment of the present application, the preparation method of the hydrophilic modified resin can include the following steps: mixing the resin and the hydrophilic modifier to carry out grafting reaction, so as to obtain the hydrophilic modified resin system.

[0037] As a specific embodiment of the present application, the mixing before can further include: the resin is subjected to a heating pretreatment, the temperature of the heating pretreatment can be 40~60℃, and can be specifically 40℃, 45℃, 50℃, 55℃ or 60℃; the time of the heating pretreatment can be 15~40min, and can be specifically 15min, 20min, 25min, 30min, 35min or 40min. The present application can reduce the viscosity of the resin through the heating pretreatment, so as to facilitate the mixing of the resin and the hydrophilic modifier.

[0038] As a specific embodiment of the present application, the hydrophilic modifier can include maleic anhydride, diethylene triamine, isocyanate or epoxy-acrylate copolymer; when the hydrophilic modifier is maleic anhydride, the mass ratio of the resin and the maleic anhydride can be 1:3~5, and can be specifically 1:3, 1:4 or 1:5; when the hydrophilic modifier is diethylene triamine, the mass ratio of the resin and the diethylene triamine can be 1:2~5, and can be specifically 1:2, 1:3, 1:4 or 1:5; when the hydrophilic modifier is isocyanate, the mass ratio of the resin and the isocyanate can be 1:2~4, and can be specifically 1:2, 1:3 or 1:4; when the hydrophilic modifier is epoxy-acrylate copolymer, the mass ratio of the resin and the epoxy-acrylate copolymer can be 1:1~3, and can be specifically 1:1, 1:2 or 1:3.

[0039] The present application can mix the resin and the hydrophilic modifier under stirring, the stirring speed can be 300~500rpm, and can be specifically 300rpm, 350rpm, 400rpm, 450rpm or 500rpm; the stirring time can be 28~32min, and can be specifically 30min.

[0040] As a specific embodiment of the present application, the temperature of the grafting reaction can be 40~60℃, and can be specifically 40℃, 45℃, 50℃, 55℃ or 60℃; the time of the grafting reaction can be 20~35min, and can be specifically 30min.

[0041] As a specific embodiment of the present application, the grafting reaction can further include: after the grafting reaction, the system is cooled to room temperature for standby; the temperature of the room temperature can be 20~35℃, and can be 25~30℃.

[0042] The present application combines the plant fiber material with the resin system that can be hydrolyzed, and obtains the degradable green composite material, which has the characteristics of lightweight and durability, and can effectively replace the traditional high-density material.

[0043] The present application further provides a preparation method of the plant fiber composite material, including the following steps: The plant fiber and the resin system are mixed and then heat treated to obtain a prepreg; The prepreg is laminated and then formed to obtain the plant fiber composite material.

[0044] The plant fiber and the resin system are mixed and then heat treated to obtain a prepreg. As a specific embodiment of the present application, the resin and the curing agent are mixed to obtain a resin system; the present application does not have special requirements for the way of mixing the resin and the curing agent as long as it can be uniformly mixed.

[0045] As a specific embodiment of the present application, when the plant fiber is bamboo powder or wood powder, the way of mixing the plant fiber and the resin system can be stirring the plant fiber and the resin system; the present application does not have special requirements for the stirring as long as it can be uniformly mixed. When the plant fiber is one or more of plant fiber felt, bamboo skin, wood skin, woven plant fiber yarn, woven bamboo filament, unidirectional plant fiber yarn and unidirectional bamboo filament, the way of mixing the plant fiber and the resin system can be impregnating the plant fiber with the resin system and then laying up to obtain a blank.

[0046] As a specific embodiment of the present application, the temperature of the heat treatment can be 80-120℃, which can be specifically 80℃, 85℃, 90℃, 95℃, 100℃, 110℃ or 115℃; the holding time of the heat treatment can be 1-6h, which can be specifically 1h, 1.5h, 2h, 3h, 4h, 5h or 6h; the present application can remove part of the solvent in the resin system through heat treatment, so that the resin system is preliminarily crosslinked to reach a semi-cured state, forming a prepreg.

[0047] As a specific embodiment of the present application, the thickness of the prepreg can be 0.1-0.5mm, which can be specifically 0.1mm, 0.2mm, 0.3mm, 0.4mm or 0.5mm. The present application can cut the prepreg according to the requirements of subsequent forming.

[0048] The degradable plant fiber reinforced resin prepreg provided by the present application has good forming performance and durability, can replace traditional plastic materials, and has important practical value.

[0049] After obtaining the prepreg, the present application stacks the prepreg and forms the plant fiber composite material. The present application does not have special requirements for the number of layers of the stack, which can be set according to the required thickness of the fiber composite material. As a specific embodiment of the present application, the forming method can include hot pressing or heat-assisted vacuum lamination; the temperature of the hot pressing can be 120-200℃, which can be specifically 120℃, 140℃, 150℃, 160℃, 180℃ or 200℃, and the present application can be heated to the required temperature of the hot pressing in two stages, specifically heated to 100-110℃ within 0-10min and then heated to the required temperature of the hot pressing within 10-20min; the pressure of the hot pressing can be 3-10MPa, which can be specifically 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa or 10MPa; the holding time of the hot pressing can be 15-60min, which can be specifically 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min.

[0050] As a specific embodiment of the present application, the heat-assisted vacuum lamination can be placing the stacked prepreg in a vacuum bag, sealing the vacuum bag and connecting a vacuum pump; turning on the vacuum pump to reduce the pressure in the vacuum bag to -0.08MPa-0.1MPa, while maintaining this vacuum degree, heating the temperature to 80-150℃ at a heating rate of 1-5℃ / min, and holding for 10-30min to preliminarily remove air and volatiles. Subsequently, 0.2-0.5MPa pressure is applied through a hot press or external pressure equipment, while maintaining a vacuum state and a temperature of 120-180℃ for 30-90min for lamination and curing. In the present application, the vacuum lamination is suitable for curing the prepreg of plant fibers with a fiber content >60%. The voids between plant fibers in high-fiber-content materials are relatively small, and the use of vacuum lamination process can remove air between fibers under negative pressure, allowing the resin system to penetrate more fully into the fiber bundle, achieving better impregnation effect, ensuring good bonding between plant fibers and resin system, thereby improving the overall performance of the fiber composite material. The heat-assisted vacuum lamination method in the present application effectively improves the flowability of the resin system and the ability to penetrate the pores of the plant fibers, improving production efficiency.

[0051] As a specific embodiment of the present application, when the plant fiber is one or more of bamboo skin, wood skin, woven plant fiber yarn, woven bamboo filament, unidirectional plant fiber yarn and unidirectional bamboo filament, the orientation of the plant fiber in different layers during the laminating process of the prepreg can form an included angle, and the angle of the included angle can be 0-90°, and can be specifically 30°, 45° or 90°. The present application can improve the mechanical strength of the fiber composite material by limiting the included angle between different layers. The present application adopts a multi-layer prepreg cross-laminating method, so that the fiber composite material can obtain good mechanical strength in all directions, thereby expanding the application range of the fiber composite material.

[0052] As a specific embodiment of the present application, the molding product can further include: demolding after cooling the molded product, and performing surface treatment on the demolded product to obtain the plant fiber composite material. As a specific embodiment of the present application, the temperature after cooling can be below 60℃, and can also be 40-50℃. The present application does not have special requirements for the cooling method, as long as the required temperature can be reached.

[0053] As a specific embodiment of the present application, the surface treatment can include surface roughening and / or setting a water-blocking layer on the surface; the surface roughening can include chemical etching or mechanical sand blasting; the solvent for the chemical etching can be sodium persulfate; setting the water-blocking layer can be coating bisphenol A type epoxy resin on the surface of the fiber composite material and then curing to form a water-blocking layer; the curing temperature can be 115-120℃, the holding time of the curing can be 25-30min, and the thickness of the water-blocking layer can be 18-20μm.

[0054] The surface roughening of the plant fiber composite material of the present application can enhance the bonding force.

[0055] The present application also provides the use of the plant fiber composite material in the above technical solution in the preparation of a printed circuit board.

[0056] The present application also provides a printed circuit board, characterized in that it comprises a substrate, copper cladding, printed ink, solder resist, shielding layer and solder pad. The substrate is formed of the plant fiber composite material in the above technical solution.

[0057] The printed circuit board (PCB substrate) provided by the present application can be applied in communication, computer, automotive electronics, industrial electronics, consumer electronics, medical devices, aerospace, etc.

[0058] In order to further illustrate the present application, the technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0059] Example 1 1. Raw material preparation 1) Hydrophobic modified plant fiber: Bamboo fiber mat (areal density 300 g / m 2 , fiber length 50 mm) was selected as the plant fiber. The bamboo fiber mat was soaked in deionized water for 20 min and then ultrasonically cleaned for 10 min. After filtration, the obtained solid was dried at 70°C for 24 h. The dried product was immersed in a NaOH solution (5 wt%) and soaked at 60°C for 3 h (hydrophobic modification). Then, it was transferred to deionized water and soaked for 10 min, followed by ultrasonic cleaning for 10 min. The water-washed bamboo fiber mat was dried at 60°C for 24 h to obtain the hydrophobic modified bamboo fiber mat.

[0060] 2) Resin system: NPEL-127E (hydrolytic chlorine content 280 ppm, epoxy equivalent weight 180 g / eq, viscosity 9000 cps, tensile strength after curing 60 MPa, hydrolysis half-life 30 days at 60°C water) was used as the resin; ethylenediamine was used as the curing agent. 300 g of NPEL-127E and 90 g of ethylenediamine were mixed to obtain the resin system.

[0061] 2. Prepreg preparation The hydrophobic modified bamboo fiber mat was immersed in the resin system (with stirring) for 10 min, and the mass percentage of the resin system in the immersion system was 35%. The immersed mat was taken out and laid on a stainless steel mesh, and then heat treated in an 80°C oven for 2 h to form a prepreg with a thickness of 0.3 mm.

[0062] 3. Lamination After the prepreg was cut into blocks of 100 mm x 100 mm x 0.3 mm, 5 layers of prepreg were alternately stacked with a fiber orientation angle of 90° between layers. The stack was hot-pressed at 140°C (staged heating: 5 min to 100°C, 15 min to 140°C) and 6 MPa for 25 min, and then cooled to 60°C for demolding to obtain a fiber composite material.

[0063] 4. Post-processing The fiber composite material was cut to the target size using a numerical control milling machine, and the edge roughness Ra was ≤0.8 μm. A bisphenol A type epoxy resin was coated on the surface of the fiber composite material (thickness 20 μm), and cured at 120°C for 30 min to form a water-blocking layer.

[0064] Example 2 1. Raw material preparation 1) Plant fiber: Bamboo powder (average particle size 50 μm) was selected.

[0065] 2) Hydrophilic modified resin system: South Asia epoxy resin NPEL-128G (tensile strength after curing 58 MPa, hydrolysis half-life 35 days @ 60°C water, hydrolysis chlorine content 138 ppm, epoxy equivalent weight 186 g / eq, viscosity 13000 cp) as resin; After preheating 1 part of resin at 50°C for 30 min, 3 parts of maleic anhydride were added to a beaker, and a grafting reaction was carried out by placing it in a 50°C water bath (with 350 rpm mechanical stirring) for 30 min, and then cooling to room temperature (25°C) to obtain a hydrophilic modified resin; Mix 300 g of hydrophilic modified resin and 150 g of maleic anhydride to obtain a hydrophilic modified resin system.

[0066] 2. Prepreg preparation After mixing the bamboo powder and the hydrophilic modified resin system at a mass ratio of 20:80 at room temperature (25°C) for 20 min, pour it into a 100 mm x 100 mm x 0.2 mm mold, and place it in a 90°C oven for heat treatment for 1 h to form a prepreg.

[0067] 3. Laminating Stack 4 layers of 100 mm x 100 mm x 0.2 mm prepreg, heat press at 150°C (staged heating: 10 min to 110°C, 15 min to 150°C), 5 MPa, and hold for 20 min, then cool to 60°C and demold to obtain a fiber composite material.

[0068] 4. Post-processing Cut the fiber composite material to the target size using a numerical control milling machine, with an edge roughness Ra≤0.8 μm, and coat a bisphenol A type epoxy resin (thickness 20 μm) on the surface of the fiber composite material, and cure at 120°C for 30 min to form a water barrier layer.

[0069] Example 3 1. Raw material preparation 1) Modified plant fiber: woven hemp fiber yarn (areal density: 120 g / m 2 , grid spacing 5 mm) was selected as the plant fiber; the plant fiber was hydrophobically modified using a KH570 silane coupling agent solution, and the mass ratio of plant fiber to KH570 silane coupling agent was 100:1; Dissolve KH570 silane coupling agent in an ethanol aqueous solution (volume ratio of ethanol to water 9:1), add acetic acid to adjust the pH value of the system to 4, and then stir at room temperature (25°C) for 30 min to form a silane coupling agent solution; The plant fiber was soaked in deionized water for 20 min and then ultrasonically cleaned for 10 min. The obtained solid was dried at 70°C for 24 h. The dried product was immersed in a silane coupling agent solution at a solid-liquid ratio of 1:5, stirred at room temperature (25°C) for 2 h, filtered, and then condensed in an oven at 100°C for 1 h to obtain the hydrophobically modified plant fiber.

[0070] 2) Resin system: The resin system was prepared by mechanically stirring 350 g of American Hansen epoxy resin Epikote 828EL (tensile strength after curing 50 MPa, hydrolysis half-life 20 days @ 60°C water, hydrolysis chlorine content 132 ppm, epoxy equivalent weight 188 g / eq, viscosity 13000 cps), 200 g of triethylenetetramine, and 20 g of ceramic particles. The resin system was prepared by mechanically stirring 350 g of American Hansen epoxy resin Epikote 828EL (tensile strength after curing 50 MPa, hydrolysis half-life 20 days @ 60°C water, hydrolysis chlorine content 132 ppm, epoxy equivalent weight 188 g / eq, viscosity 13000 cps), 200 g of triethylenetetramine, and 20 g of ceramic particles.

[0071] 2. Preparation of prepreg The hydrophobically modified plant fiber was placed in a 100 mm x 100 mm x 0.2 mm mold, and the resin system was injected. The mold was heated in an oven at 85°C for 1.5 h to form a prepreg. The mass percentage of the resin system in the total mass of the resin system and the hydrophobically modified plant fiber was 30%.

[0072] 3. Laminating The above-mentioned 3 layers of 100 mm x 100 mm x 0.2 mm prepreg were alternately stacked with a fiber orientation angle of 45° between layers, and then placed in a vacuum bag. The pressure in the vacuum bag was set to -0.08 MPa, and the temperature was increased to 80°C at a rate of 5°C / min, and held for 20 min. A pressure of 0.4 MPa was applied by an external press, and the temperature was increased to 160°C and held for 40 min. After cooling to room temperature (25°C), the fiber composite material was demolded.

[0073] 4. Post-processing The fiber composite material was cut to the target size using a numerical control milling machine, and the edge roughness Ra was ≤0.8 μm. A bisphenol A type epoxy resin was coated on the surface of the fiber composite material (thickness 20 μm), and cured at 120°C for 30 min to form a water-blocking layer.

[0074] Comparative Example 1 A glass fiber epoxy resin plate (3240 epoxy glass fiber resin plate, purchased from Shenzhen Jianduan Plastic Material Co., Ltd.) was used as a comparative example.

[0075] Figure 1 A physical diagram of the prepreg prepared in Example 1, Figure 2The fiber composite material prepared in Example 1 was used to prepare a real object.

[0076] The density, mechanical properties and hydrolysis properties of the plates of Examples 1-3 and Comparative Example 1 were tested according to the methods of GB / T 1303-2009 Glass Fibre Reinforced Laminated Products for Electrical Engineering, GB / T 1447-2005 Tensile Properties Test Method for Fiber Reinforced Plastics, GB / T 1449-2005 Flexural Properties Test Method for Fiber Reinforced Plastics, GB / T 1451-2005 Izod Impact Test Method for Fiber Reinforced Plastics, and GB / T 2573-2008 Chemical Resistance Test Method for Fiber Reinforced Plastics, and the results are shown in Table 1.

[0077] Table 1 Properties of the materials of Examples 1-3 and Comparative Example 1

[0078] As can be seen from Table 1, the plant fiber composite material provided by the application has the characteristics of light weight and good mechanical properties, and can be directly hydrolyzed in water, which is beneficial to the recovery of precious metals when used as a substrate to prepare a PCB board, and reduces environmental pollution.

[0079] Although the above examples have described the application in detail, it is only a part of the embodiments of the application, not all the embodiments, and other embodiments can be obtained according to the embodiments without creativity, which are within the protection scope of the application.

Claims

1. A plant fiber composite material, characterized by, The preparation raw material of the plant fiber composite material comprises a resin system and plant fibers; The resin system comprises a resin and a curing agent; The resin comprises a controllable hydrolysis epoxy resin, polyvinyl alcohol, sulfonated unsaturated polyester resin, esterified polyurethane resin or esterified phenolic resin; The mass percentage of the plant fibers in the preparation raw material is 5-85%.

2. The plant fiber composite material according to claim 1, characterized in that, The plant fibers comprise hydrophobic modified plant fibers, and the resin system comprises hydrophilic modified resin; The hydrophobic modified plant fibers and the hydrophilic modified resin cannot exist simultaneously.

3. The plant fiber composite material according to claim 2, characterized in that, The preparation method of the hydrophobic modified plant fibers comprises the following steps: mixing plant fibers and a hydrophobic modification solution to modify, so as to obtain the hydrophobic modified plant fibers; The hydrophobic modification solution comprises a coupling agent solution or an alkaline solution; The coupling agent solution comprises a silane coupling agent solution or a titanate coupling agent solution; The alkaline solution comprises a sodium hydroxide solution, a potassium hydroxide solution or a calcium hydroxide solution.

4. The plant fiber composite material according to claim 2, characterized in that, The preparation method of the hydrophilic modified resin comprises the following steps: mixing resin and a hydrophilic modifier to carry out grafting reaction, so as to obtain the hydrophilic modified resin; The hydrophilic modifier comprises maleic anhydride, diethylene triamine, isocyanate or epoxy-acrylate copolymer; The temperature of the grafting reaction is 40-60 ℃, and the time of the grafting reaction is 20-35 min.

5. The plant fiber composite material according to claim 1, characterized in that, The curing agent comprises an amine curing agent or an acid anhydride curing agent; The amine curing agent comprises ethylenediamine, hexamethylenediamine, diethylene triamine, triethylene tetramine, diethylaminopropylamine or m-phenylenediamine; The acid anhydride curing agent comprises maleic anhydride or phthalic anhydride; The mass percentage of the curing agent in the resin system is 10-60%.

6. The plant fiber composite material according to claim 1 or 5, characterized in that, The resin system further comprises a filler; The filler comprises one or more of silica powder, quartz powder, aluminum powder, copper powder, ceramic particles, carbon black, zinc oxide, titanium oxide, polystyrene and polymethyl methacrylate.

7. Process for the production of a plant fibre composite material according to any one of claims 1 to 6, characterised in that, The method comprises the following steps: Mixing plant fibers and a resin system and then heat treating to obtain a prepreg; Stacking the prepreg to form the plant fiber composite material.

8. The preparation method according to claim 7, characterized in that, The temperature of the heat treatment is 80-120 ℃, and the holding time of the heat treatment is 1-6 h; The forming mode comprises hot pressing or hot assisted vacuum lamination; The temperature of the hot pressing is 120-200 ℃; the pressure of the hot pressing is 3-10 MPa; and the holding time of the hot pressing is 15-60 min.

9. Use of the plant fiber composite material according to any one of claims 1-6 in the preparation of a printed circuit board.

10. A printed circuit board, characterized by The printed circuit board comprises a substrate, copper cladding, printed ink, solder resist, shielding layer and solder pad; The substrate is formed of the plant fiber composite material according to any one of claims 1-6.

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