Acrylic composite electronic product shell base material, structural member and preparation method of acrylic composite electronic product shell base material

Abstract

The invention relates to the technical field of composite electronic product shells, in particular to an acrylic composite electronic product shell base material, a structural part and a preparation method of the acrylic composite electronic product shell base material and the structural part. The method comprises the following steps that S1, in-situ polymerization raw materials are mixed and prepared into pulp, then the pulp and fiber cloth are prepared into supporting layers through an in-situ polymerization technology, and the multiple supporting layers are stacked together; s2, covering at least one reinforcing layer on the upper surface of the supporting layer; s3, covering at least one strengthening layer on the lower surface of the supporting layer; and S4, putting the stacked supporting layer and strengthening layer into a mold together, and then carrying out ultrasonic welding. The base material prepared by the method has the characteristics of being light and thin, good in melt fluidity and good in infiltration effect on a fiber matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of composite electronic product shells, and in particular to an acrylic composite electronic product shell substrate, a structural part and a preparation method thereof. Background Art

[0002] As 5G communication technology drives innovation and upgrades in the consumer electronics industry, the evolution of terminal products exhibits three notable characteristics: accelerated hardware iteration cycles, the mainstream adoption of highly integrated designs, and a growing demand for portability in mobile devices. This technological shift is forcing upstream structural component suppliers in the supply chain to simultaneously improve product performance. This is particularly true for protective structural components for terminal devices, where the market's demand for a balance between mechanical strength and lightweight design has reached a new level of sophistication.

[0003] The current material systems for protective structural components in consumer electronics are primarily composed of three categories: engineering plastics, metal alloys, and specialty glass. Specialty glass, with its unique optical performance and tactile feedback, has long dominated the mobile terminal exterior component market for the past decade. However, the inherent brittleness of this material system makes its drop resistance performance inadequate to meet the structural design requirements of new flexible electronic devices such as foldable phones. This physical property shortcoming severely limits its application prospects in next-generation smart devices.

[0004] To overcome this technical bottleneck, material manufacturers have developed composite, light-transmitting substrates such as polycarbonate / polymethyl methacrylate (PC / PMMA) composites and epoxy resin glass fiber reinforced boards. However, engineering practice has shown that these alternative materials still have systemic deficiencies in key performance indicators such as overall strength, puncture resistance, environmental tolerance, and appearance, and have yet to fully replace the existing material system. Specifically, glass materials are relatively fragile and easily broken; PC / PMMA boards have insufficient puncture resistance, posing a safety hazard; and epoxy glass fiber boards are highly hygroscopic and, as a thermosetting material, difficult to recycle. In contrast, acrylic (PMMA) fiber composites offer excellent overall performance and are relatively low in cost, but their poor melt flowability and poor wetting into the fiber matrix make it difficult to manufacture high-performance acrylic substrate materials. Summary of the Invention

[0005] In view of this, a lightweight acrylic composite electronic product housing substrate, a structural component and a preparation method thereof are provided, which have good melt fluidity and good fiber matrix impregnation effect.

[0006] In order to achieve the above objects, the technical solution adopted by the present invention is: An acrylic composite electronic product housing substrate comprises a plurality of supporting layers and a plurality of strengthening layers, wherein the plurality of strengthening layers are attached to the upper and lower surfaces of the plurality of supporting layers, and at least one strengthening layer is attached to each surface of the supporting layer. Each supporting layer is an acrylic fiber cloth composite substrate made by in-situ polymerization of raw materials and fiber cloth, and each strengthening layer is an acrylic film made by extrusion casting of acrylic resin.

[0007] Preferably, the in-situ polymerization raw material includes, by mass, 30-90% of MMA monomer, 5-50% of nano inorganic filler, 3-20% of cross-linking agent, and 0.1-1% of initiator.

[0008] Further preferably, the nano inorganic filler includes one or a mixture of two or more of nano zirconium dioxide, nano silicon nitride, nano silicon carbide, nano alumina, nano aluminum nitride, nano silicon dioxide, fumed silicon, nano boron nitride, carbon nanotubes, graphene, talc, and kaolin.

[0009] Preferably, the fiber cloth includes one of poly(p-phenylene benzobisoxazole) fiber cloth, glass fiber cloth, carbon fiber cloth, aramid fiber cloth, and basalt fiber cloth.

[0010] Further preferably, the cross-linking agent includes one of acrylic acid or acrylonitrile, and the initiator includes one of azo compound or organic peroxide.

[0011] Preferably, the number of the supporting layer is 1 to 20, and the number of the strengthening layer located on one side of the supporting layer is 1 to 5.

[0012] Preferably, the thickness of a single layer in the multiple reinforcement layers is 0.01 mm to 0.3 mm.

[0013] Preferably, the thickness of a single layer in the multi-layer support layer is 0.05 mm to 0.2 mm.

[0014] An acrylic composite electronic product housing structural component is obtained by subjecting the acrylic composite electronic product housing substrate to hot pressing, air pressure forming or vacuum forming.

[0015] A method for preparing an acrylic composite electronic product housing substrate, using the above-mentioned acrylic composite electronic product housing substrate, the method for preparing the acrylic composite electronic product housing substrate comprises the following steps: S1, mixing the in-situ polymerization raw materials and preparing the slurry with the fiber cloth through an in-situ polymerization process to prepare a support layer, and stacking multiple support layers together; S2, covering the upper surface of the support layer with at least one strengthening layer; S3, covering the lower surface of the support layer with at least one strengthening layer; S4, after placing the stacked support layer and reinforcement layer into the mold together, ultrasonic welding is performed. Ultrasonic welding is used between multiple support layers, between multiple reinforcement layers, and between reinforcement layers and support layers. The welding temperature is set between 200~300℃, the welding time is 0.3~1s, and the vibration frequency is controlled at 15~40kHz.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: First, the present invention designs a structure in which multiple reinforcement layers are composited with multiple support layers, specifically a structure in which multiple acrylic films are composited with multiple acrylic fiber cloth composite substrates. The shell substrate made of this structure has good overall mechanical properties and high puncture strength.

[0017] Second, by in-situ polymerizing nano-inorganic fillers, cross-linking agents, initiators, and MMA monomers with fiber cloth to obtain a support layer, the composite substrate has excellent mechanical properties. Specifically, by uniformly dispersing and mixing nano-inorganic fillers in the acrylic fiber cloth composite support layer, the overall puncture resistance and bending resistance of the acrylic material are further improved. The support layer prepared by this method is evenly impregnated and not easily warped by heat.

[0018] Third, ultrasonic waves are used to weld the support layer and the reinforcement layer, and the reinforcement layer and the reinforcement layer. The method is simple, the cost is reduced, and the bonding effect is good.

[0019] Fourth, the strengthening layer is an acrylic film obtained by casting or calendering, and the thickness is controllable. The base material obtained by compounding the strengthening layer and the supporting layer is light and thin. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic diagram of the steps of a method for preparing an acrylic composite electronic product housing substrate according to an embodiment of the present invention.

[0021] Figure 2 The figure is a schematic diagram of the cross-sectional structure of an acrylic composite electronic product housing substrate according to an embodiment of the present invention.

[0022] Figure 2 middle, 1. Strengthening layer; 2. Support layer. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] See also Figures 1 to 2 , showing an acrylic composite electronic product housing substrate structure and a preparation method thereof provided by an embodiment of the present invention.

[0025] On the one hand, an embodiment of the present invention provides an acrylic composite electronic product housing substrate, which includes a multi-layer support layer 2 and a multi-layer reinforcement layer 1. The multi-layer reinforcement layer 1 is attached to the upper surface and the lower surface of the multi-layer support layer 2. At least one layer of the reinforcement layer 1 is attached to each surface of the support layer 2. Each of the support layers 2 is an acrylic fiber cloth composite substrate made by in-situ polymerization of raw materials and fiber cloth, and each of the reinforcement layers 1 is an acrylic film made by extrusion casting of acrylic resin.

[0026] Specifically, the in-situ polymerization raw materials include 30-90% by mass of MMA monomer, 5-50% by mass of nano inorganic filler, 3-20% by mass of cross-linking agent, and 0.1-1% by mass of initiator.

[0027] More specifically, the nano inorganic filler includes one or a mixture of two or more of nano zirconium dioxide, nano silicon nitride, nano silicon carbide, nano alumina, nano aluminum nitride, nano silicon dioxide, fumed silicon, nano boron nitride, carbon nanotubes, graphene, talc, and kaolin.

[0028] Specifically, the fiber cloth includes one of poly(p-phenylene benzobisoxazole) fiber cloth, glass fiber cloth, carbon fiber cloth, aramid fiber cloth, and basalt fiber cloth.

[0029] More specifically, the cross-linking agent includes one of acrylic acid or acrylonitrile, and the initiator includes one of azo compound or organic peroxide. In some specific embodiments, the in-situ polymerization initiator is one of azo compound or organic peroxide. Preferably, the fiber cloth is also subjected to surface activation treatment with a coupling agent. The coupling agent is used to increase the surface activity of the fiber cloth so that it can be better mixed with the resin slurry. More preferably, the fiber cloth is pre-treated by soaking in a 1% alcohol solution of a silane coupling agent to activate the surface of the fiber cloth and enhance its compatibility with the acrylic polymer. By introducing an acrylic acid or acrylonitrile cross-linking agent and copolymerizing it with the MMA monomer, the in-situ polymerization reaction forms a hydrogen bond cross-linking structure, thereby improving the strength of the material system.

[0030] Specifically, the number of layers of the support layer 2 is 1 to 20, wherein the support layer 2 is preferably 2 to 4 layers, and the number of layers of the reinforcement layer 1 located on a single side of the support layer 2 is 1 to 5 layers. More than one layer of the reinforcement layer 1 is attached to each surface of the support layer 2 because this prevents the fibers from being exposed on the surface, thereby improving surface smoothness and surface hardness, achieving stress matching, reducing thermal deformation, and more effectively improving overall mechanical properties and puncture strength. wherein the number of layers of the reinforcement layer 1 located on a single side of the support layer 2 is preferably 2 to 3 layers.

[0031] Specifically, the thickness of a single layer in the multi-layer strengthening layer 1 is 0.01 mm to 0.3 mm.

[0032] Specifically, the thickness of a single layer in the multi-layer support layer 2 is 0.05 mm to 0.2 mm.

[0033] Another aspect of the embodiments of the present invention provides an acrylic composite electronic product housing structure, which is obtained by hot pressing, air pressure forming or vacuum forming the acrylic composite electronic product housing substrate.

[0034] Another embodiment of the present invention provides a method for preparing the acrylic composite electronic product housing substrate, comprising the following steps: S1, mixing the in-situ polymerization raw materials and preparing the slurry with the fiber cloth through an in-situ polymerization process to prepare a support layer 2, and stacking multiple support layers 2 together; S2, covering the upper surface of the support layer 2 with at least one strengthening layer 1; S3, covering the lower surface of the support layer 2 with at least one strengthening layer 1; S4, placing the stacked support layer 2 and reinforcement layer 1 into a mold together and then performing ultrasonic welding. Ultrasonic welding is used between multiple support layers 2, between multiple reinforcement layers 1, and between reinforcement layer 1 and support layer 2. The welding temperature is set between 200~300℃, the welding time is 0.3~1s, and the vibration frequency is controlled at 15~40kHz.

[0035] The following uses multiple examples to illustrate the steps of the method for preparing an acrylic composite electronic product housing substrate, as well as the performance of the resulting acrylic composite electronic product housing structural component.

[0036] In all embodiments, the raw materials for in-situ polymerization are 30-90% MMA monomer, 5-50% nano-inorganic filler, 3-20% cross-linking agent, and 0.1-1% initiator by weight. The in-situ polymerization initiator is an azo compound or an organic peroxide. The fiber cloth is also subjected to surface activation treatment with a coupling agent. The fiber cloth is pre-treated by soaking in a coupling agent solution to activate the surface and enhance its compatibility with the acrylic polymer. By introducing an acrylic acid or acrylonitrile cross-linking agent and copolymerizing it with the MMA monomer, the in-situ polymerization reaction forms a hydrogen bond cross-linking structure, thereby improving the strength of the material system. When performing ultrasonic welding between the support layers 2, between the reinforcement layers 1, and between the reinforcement layer 1 and the support layer 2, the vibration frequency is controlled to be between 15-40 kHz, the temperature is between 200-300°C, and the time is controlled to be between 0.3-1s.

[0037] Example 1 Preparation of the support layer: Disperse 60g of nano-γ-alumina with an average particle size of 200nm, 42.8g of methacrylic acid, and 1.1g of azoisobutyl cyanide in 297.2g of MMA monomer and stir to obtain a uniform mixture. S-glass fibers cut into 10.5-inch pieces were placed in a 1% (mass fraction) KH550 alcohol solution, ultrasonically treated for 15 minutes, and air-dried to obtain a surface-treated S-glass fiber cloth. The surface-treated S-glass fibers were then placed in the MMA mixture to uniformly soak the fibers. The fibers were then pre-polymerized in an oven at 40°C for 5 hours and cured at 100°C for 4 hours to obtain a 0.08mm thick support layer.

[0038] Preparation of the strengthening layer: Powdered PMMA, silicon dioxide, zirconium oxide and other additives are weighed in a certain proportion and mixed evenly, and cast on a polymer extrusion casting machine to obtain a 0.1 mm thick acrylic sheet strengthening layer.

[0039] Two support layers cut to the appropriate size using a die-cutter are laminated together. Two acrylic reinforcement layers are attached to the upper and lower surfaces of the laminated support layers. The laminate is then placed in a mold and ultrasonically welded at 240°C for 0.5 seconds to create an acrylic electronic product housing substrate. The acrylic electronic product housing substrate is then placed in a mold in a high-pressure hot press and hot-pressed at 150°C for 30 seconds at 650 kgf / cm². The resulting acrylic composite electronic product housing structural component has a thickness of 0.32 mm and a puncture strength of 114.64 N using a 1mm needle. The 100-grid peel test results are 4B.

[0040] Example 2 Preparation of the support layer: Disperse 132g of yttrium-stabilized zirconia with an average particle size of 500nm, 20.8g of acrylonitrile, and 1.1g of azoisobutyl cyanide in 247.2g of MMA monomer and stir to obtain a uniform mixture. S-glass fibers cut into 10.5-inch pieces were placed in a 1% (mass fraction) KH550 alcohol solution and soaked for 2 hours to obtain a surface-treated S-glass fiber woven fabric. The surface-treated S-glass fibers were then placed in the MMA mixture to uniformly soak the fibers. The fibers were then pre-polymerized in an oven at 40°C for 5 hours and cured at 100°C for 4 hours to obtain a 0.08mm thick support layer.

[0041] Preparation of the strengthening layer: Powdered PMMA, silicon dioxide, zirconium oxide and other additives are weighed in a certain proportion and mixed evenly, and cast on a polymer extrusion casting machine to obtain a 0.1 mm thick acrylic sheet strengthening layer.

[0042] Two support layers cut to the appropriate size using a die-cutter are laminated together. Two acrylic reinforcement layers are attached to the upper and lower surfaces of the laminated support layers. The laminated layers are then placed in a mold and ultrasonically welded at 240°C for 0.5 seconds to create an acrylic electronic product housing substrate. The acrylic electronic product housing substrate is then placed in a mold in a high-pressure hot press and hot-pressed at 150°C for 30 seconds at 650 kgf / cm². The resulting acrylic composite electronic product housing structural component has a thickness of 0.32 mm and a puncture strength of 108.4 N using a 1 mm needle, and a 4B peel test result using a 100-grid peel test.

[0043] Example 3 Preparation of the support layer: Disperse 80g of silica with an average particle size of 100nm, 35.68g of acrylonitrile, and 1.1g of azoisobutyl cyanide in 284.32g of MMA monomer and stir to obtain a uniform mixture. S-glass fiber, cut into 10.5-inch pieces, is placed in a 1% by weight KH550 alcohol solution and soaked for 2 hours to obtain a surface-treated S-glass fiber cloth. The surface-treated S-glass fiber is then placed in the MMA mixture to uniformly soak it. The fiber is then removed and placed in an oven for prepolymerization at 40°C for 5 hours, followed by curing at 100°C for 4 hours to obtain a 0.08mm thick support layer.

[0044] Preparation of the strengthening layer: Powdered PMMA, silicon oxide, zirconium oxide and other additives are weighed in a certain proportion and mixed evenly, and cast on a polymer extrusion casting machine to obtain a 0.1 mm thick acrylic sheet strengthening layer.

[0045] Three support layers, cut to the appropriate size using a die-cutter, were laminated together. An acrylic reinforcement layer was attached to the upper and lower surfaces of the laminated support layers. The laminated layers were then placed in a mold and ultrasonically welded at 240°C for 0.5 seconds to create an acrylic electronic product housing substrate. The acrylic electronic product housing substrate was then placed in a mold in a high-pressure hot press and hot-pressed at 150°C for 30 seconds at 650 kgf / cm². The resulting acrylic composite electronic product housing structural component had a thickness of 0.28 mm and achieved a 1mm needle puncture strength of 118.7 N, with a 4B peel test score.

[0046] Example 4 Preparation of the support layer: Disperse 150g of silica with an average particle size of 100nm, 66g of nano-γ-alumina with an average particle size of 200nm, 28g of methacrylic acid, and 1.1g of azoisobutyl cyanide in 156g of MMA monomer and stir to obtain a uniform mixture. E-glass fiber cut into 10.5-inch pieces was placed in a 1% by weight KH550 alcohol solution and soaked for 2 hours to obtain a surface-treated E-glass fiber cloth. The surface-treated E-glass fiber was placed in the MMA mixture to uniformly soak the surface. The fiber was then removed and pre-polymerized in an oven at 40°C for 5 hours, followed by curing at 100°C for 4 hours to obtain a 0.065mm thick support layer.

[0047] Preparation of the strengthening layer: Powdered PMMA, silicon oxide, zirconium oxide and other additives are weighed in a certain proportion and mixed evenly, and cast on a polymer extrusion casting machine to obtain a 0.1 mm thick acrylic sheet strengthening layer.

[0048] Three support layers, cut to the appropriate size using a die-cutter, were laminated together. Two acrylic reinforcement layers were attached to the upper and lower surfaces of the laminated support layers. The laminated layers were then placed in a mold and ultrasonically welded at 240°C for 0.5 seconds to create an acrylic electronic product housing substrate. The acrylic electronic product housing substrate was then placed in a mold in a high-pressure hot press and hot-pressed at 150°C for 30 seconds at 650 kgf / cm². The resulting acrylic composite electronic product housing structural component had a thickness of 0.30 mm and achieved a 1mm needle puncture strength of 78.2N and a 3B peel test score on a 100-grid peel test.

[0049] Example 5 Preparation of the support layer: Disperse 140g of hexagonal boron nitride with an average particle size of 400nm, 41g of methacrylic acid, and 1.1g of azoisobutyl cyanide in 219g of MMA monomer and stir to obtain a uniform mixture. E-glass fiber sheets cut into 10.5-inch pieces were placed in a 1% (mass fraction) KH550 alcohol solution and soaked for 2 hours to obtain a surface-treated E-glass fiber cloth. The surface-treated E-glass fibers were then placed in the MMA mixture to uniformly soak the fibers. The fibers were then pre-polymerized in an oven at 40°C for 5 hours and cured at 100°C for 4 hours to obtain a 0.065mm thick support layer.

[0050] Preparation of the strengthening layer: Powdered PMMA, silicon oxide, zirconium oxide and other additives are weighed in a certain proportion and mixed evenly, and cast on a polymer extrusion casting machine to obtain a 0.1 mm thick acrylic sheet strengthening layer.

[0051] Four support layers, cut to the appropriate size using a die-cutter, were laminated together. Two acrylic reinforcement layers were attached to the upper and lower surfaces of the laminated support layers. The laminated layers were then placed in a mold and ultrasonically welded at 240°C for 0.5 seconds to create an acrylic electronic product housing substrate. The acrylic electronic product housing substrate was then placed in a mold in a high-pressure hot press and hot-pressed at 150°C for 30 seconds at 650 kgf / cm². The resulting acrylic composite electronic product housing structural component had a thickness of 0.26 mm and achieved a 1mm needle puncture strength of 76.45 N and a 4B peel test score.

[0052] Table 1. Thickness, puncture strength and 100-grid test results of acrylic composite electronic product housing structural components prepared in Examples 1 to 5

[0053] It should be noted that the present invention is not limited to the above-mentioned embodiments. Based on the creative spirit of the present invention, those skilled in the art can also make other changes. These changes made based on the creative spirit of the present invention should be included in the scope of protection required by the present invention.

Claims

1. An acrylic composite electronic product housing substrate, characterized in that: It includes multiple supporting layers and multiple reinforcing layers, wherein the multiple reinforcing layers are attached to the upper and lower surfaces of the multiple supporting layers, and at least one reinforcing layer is attached to each surface of the supporting layer. Each supporting layer is an acrylic fiber cloth composite substrate made by in-situ polymerization of raw materials and fiber cloth, and each reinforcing layer is an acrylic film made by extrusion casting of acrylic resin.

2. The acrylic composite electronic product housing substrate according to claim 1, wherein: The in-situ polymerization raw materials include 30-90% of MMA monomer, 5-50% of nano inorganic filler, 3-20% of cross-linking agent, and 0.1-1% of initiator in a mass ratio.

3. The acrylic composite electronic product housing substrate according to claim 2, wherein: The nano inorganic filler includes one or a mixture of two or more of nano zirconium dioxide, nano silicon nitride, nano silicon carbide, nano aluminum oxide, nano aluminum nitride, nano silicon dioxide, fumed silicon, nano boron nitride, carbon nanotubes, graphene, talc, and kaolin.

4. The acrylic composite electronic product housing substrate according to claim 1, wherein: The fiber cloth includes one of poly(p-phenylene benzobisoxazole) fiber cloth, glass fiber cloth, carbon fiber cloth, aramid fiber cloth, and basalt fiber cloth.

5. The acrylic composite electronic product housing substrate according to claim 2, wherein: The cross-linking agent includes one of acrylic acid or acrylonitrile, and the initiator includes one of azo compound or organic peroxide.

6. The acrylic composite electronic product housing substrate according to claim 1, wherein: The number of the supporting layer is 1 to 20, and the number of the strengthening layer located on one side of the supporting layer is 1 to 5.

7. The acrylic composite electronic product housing substrate according to claim 1, wherein: The thickness of a single layer in the multi-layer strengthening layer is 0.01mm~0.3mm.

8. The acrylic composite electronic product housing substrate according to claim 1, wherein: The thickness of a single layer in the multi-layer support layer is 0.05 mm to 0.2 mm.

9. An acrylic composite electronic product housing structural component, characterized in that: The acrylic composite electronic product housing structural component is obtained by hot pressing, air pressure forming or vacuum forming the acrylic composite electronic product housing substrate according to any one of claims 1 to 8.

10. The method for preparing the acrylic composite electronic product housing substrate according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing the in-situ polymerization raw materials and preparing the slurry with the fiber cloth through an in-situ polymerization process to prepare a support layer, and stacking multiple support layers together; S2, covering the upper surface of the support layer with at least one strengthening layer; S3, covering the lower surface of the support layer with at least one strengthening layer; S4, after placing the stacked support layer and reinforcement layer into the mold together, ultrasonic welding is performed. Ultrasonic welding is used between multiple support layers, between multiple reinforcement layers, and between reinforcement layers and support layers. The welding temperature is set between 200~300℃, the welding time is 0.3~1s, and the vibration frequency is controlled at 15~40kHz.

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