A high-strength polypropylene hollow plastic plate and preparation method thereof

Abstract

The present invention relates to the technical field of polypropylene composite boards, specifically to a high-strength polypropylene hollow plastic board and a preparation method thereof, comprising the following processes: mixing polypropylene, maleic anhydride grafted polypropylene, filler, epoxy resin, curing agent and auxiliary agent, extruding, pulling and drawing the board to form a panel and a core layer respectively; compounding the panel and the core layer to obtain a polypropylene hollow plastic board. The panel and the core layer having a hollow structure form a polypropylene hollow plastic board, and good mechanical properties are obtained. The branched epoxy resin and the bisphenol A type epoxy resin are compounded and added to the material system of the polypropylene hollow plastic board, which increases the entanglement and cross-linking between the system molecules, so that the melt strength is enhanced, which helps to improve the mechanical properties and heat resistance, UV resistance and other properties of the prepared polypropylene hollow plastic board.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene composite plates, in particular to a high-strength polypropylene hollow plastic plate and a preparation method thereof. Background Art

[0002] With the demand for lightweight panels, sandwich panels are widely used in pressure-bearing parts such as logistics and transportation, vehicle traffic, civil engineering, and electrical equipment. Its structure is obtained by compounding panels on both sides of a light and thick core material, which has a light weight and high rigidity and strength. Common materials include polypropylene, which is extruded into sheets after high-temperature melting in an extruder. Its core material can be the same as the panel, which can be recycled and reused more conveniently and quickly. In response to people's demand for higher strength of sandwich panels, we propose a high-strength polypropylene hollow plastic board and its preparation method. Summary of the invention

[0003] The object of the present invention is to provide a high-strength polypropylene hollow plastic plate and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for preparing a high-strength polypropylene hollow plastic plate, comprising the following processes:

[0005] Polypropylene, maleic anhydride grafted polypropylene, filler, epoxy resin, curing agent and additives are mixed, extruded, pulled and formed into panels and core layers respectively; the panel and the core layer are compounded to obtain a polypropylene hollow plastic plate.

[0006] Furthermore, the polypropylene hollow plastic plate includes 2 to 3 groups of face panels, and a core layer is arranged between two adjacent groups of face panels.

[0007] Furthermore, the cross-sectional structure of the core layer is square, circular, cross-shaped or honeycomb.

[0008] Furthermore, the thickness of the polypropylene hollow plastic plate is 4 to 15 mm;

[0009] The thickness of the panel is 1 to 5 mm, and the thickness of the core layer is 2 to 10 mm.

[0010] In the above technical solution, the polypropylene hollow plastic plate (hereinafter referred to as the polypropylene plate) is formed by 2 to 3 groups of face plates and 1 to 2 groups of core layers. The polypropylene plate includes the following structures from top to bottom: face plate, core layer, face plate; or face plate, core layer, face plate, core layer, face plate. The core layer is a hollow structure, and the cross-section or longitudinal section structure of the hollow structure can be square, circular, cross-section or honeycomb, which can enable the prepared polypropylene plate to obtain good mechanical properties.

[0011] Furthermore, in the polypropylene hollow plastic plate, the panel and the core layer are made of the same material;

[0012] The amount of each component is, by mass: 85-100 parts of polypropylene, 10-15 parts of maleic anhydride grafted polypropylene, 20-30 parts of filler, 5-25 parts of epoxy resin, 0.1-5.0 parts of curing agent, and 1.0-2.0 parts of auxiliary agent.

[0013] Further, the filler includes 6 to 8 parts of talc, 10 to 15 parts of calcium carbonate, and 4 to 7 parts of glass fiber;

[0014] The additives include 0.5 to 1.0 parts of coupling agent and 0.5 to 1.0 parts of antioxidant;

[0015] The epoxy resin is a mixture of one or more of branched epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin and phenolic epoxy resin.

[0016] Polypropylene: Dongming 500N, Jiutai L5E89, from Suqian Qinfa Plastic Products Technology Co., Ltd.;

[0017] Maleic anhydride grafted polypropylene: PO 1020, from ExxonMobil Chemical Company;

[0018] Calcium carbonate: average particle size 40-50nm, sourced from Shanxi Xintai Hengxin Nanomaterials Co., Ltd.

[0019] Talc: HAR T84, from Yiruishi (Shanghai) Investment Management Co., Ltd.

[0020] Glass fiber: length 3-6mm, SiO2 content > 95.0%, sourced from Changzhou Qiushuo Chemicals Co., Ltd.

[0021] The coupling agent is one of KH-560, KH-550 and KH-570;

[0022] The antioxidants are antioxidant 1010 and antioxidant 168, with a mass ratio of 2:1.

[0023] In the above technical scheme, polypropylene is used as the main resin and calcium carbonate is used as nanoparticles. Its filling can promote the nucleation of polypropylene, improve the crystallinity of polypropylene, and help improve the strength of the composite material; talcum powder is in flaky form and cooperates with calcium carbonate as a filler of polypropylene to effectively enhance the polypropylene composite material. The addition of glass fiber, compounded with calcium carbonate and talcum powder, can further improve the strength of polypropylene. A coupling agent is added to the polypropylene board material system, which can modify the surface of filler calcium carbonate, talcum powder and glass fiber, so that it has better dispersibility in polypropylene and realizes the full performance of the material performance; maleic anhydride grafted polypropylene can also effectively improve the affinity between filler and polypropylene and the dispersibility of filler, thereby improving the mechanical properties of polypropylene board.

[0024] The use of epoxy resin and its curing agent allows it to solidify during the co-extrusion process and disperse under high shear force to form tiny particles distributed in the polypropylene system, which can effectively improve the rigidity and modulus of the polypropylene board, and the polypropylene board has better mechanical properties. The maleic anhydride grafted polypropylene component in the polypropylene board material system has an anhydride group that can react with the epoxy resin; and the epoxy resin selection includes branched epoxy resin, the epoxy functionality is greater than 2, and the curing with the polypropylene molecular chain during co-extrusion mixing can form an interpenetrating network. This increases the entanglement and cross-linking between the system molecules, so that the melt strength is enhanced, which helps to improve the mechanical properties and heat resistance, UV resistance and other properties of the prepared polypropylene hollow plastic board.

[0025] Further, the branched epoxy resin is prepared by the following process:

[0026] Under the protection of nitrogen atmosphere, benzophenone diol, bismaleimide glycidyl ether and tetrabutylammonium bromide are mixed, stirred and heated to 80-90°C, and kept warm for reaction for 24 hours; cooled to room temperature, tetrahydrofuran is added to dissolve, deionized water is added to separate layers, rotary evaporated, and vacuum dried to obtain branched epoxy resin.

[0027] Further, the branched epoxy resin is prepared from the following components by weight: 10 parts of benzophenone diol, 54-61 parts of bismaleimide glycidyl ether and 0.8-1.0 parts of tetrabutylammonium bromide.

[0028] Further, benzophenone diol is prepared by the following process:

[0029] Mix 2,4-dihydroxybenzophenone and sodium hydroxide aqueous solution, stir to dissolve, add epichlorohydrin under nitrogen atmosphere, heat to 90-95°C and react for 3-4h; wash with water at 80±2°C, dry the organic phase, filter, distill under reduced pressure, recrystallize with ethanol, and dry under vacuum to obtain epoxybenzophenone;

[0030] Mix epoxy benzophenone and potassium hydroxide aqueous solution, heat to 80-85°C, and react for 9-10 hours; add dichloromethane, separate the liquids, wash the organic phase with water, dry, distill under reduced pressure, and dry in vacuum to obtain benzophenone diol.

[0031] Further, the molar ratio of 2,4-dihydroxybenzophenone to epichlorohydrin is 1:(2.5-3.2);

[0032] The ratio of 2,4-dihydroxybenzophenone to sodium hydroxide aqueous solution is 0.2 mol / 100 mL;

[0033] The concentration of the aqueous sodium hydroxide solution was 2M.

[0034] Further, the ratio of epoxybenzophenone to potassium hydroxide aqueous solution is 30 g / 10 mL;

[0035] The concentration of the potassium hydroxide aqueous solution was 30 wt %.

[0036] Further, bismaleimide glycidyl ether is prepared by the following process:

[0037] Mix bismaleimide, trimethylolpropane tris(3-mercaptopropionate) and a catalyst in chloroform, heat to 58-62°C under nitrogen atmosphere, and stir to react for 100-150 minutes; distill under reduced pressure, wash, and dry to obtain bismaleimide mercaptopropionate;

[0038] Maleimide mercaptopropionate, allyl glycidyl ether and a photoinitiator are mixed in chloroform, and subjected to ultraviolet irradiation for reaction for 4 to 5 hours; distilled under reduced pressure, washed and dried to obtain bismaleimide glycidyl ether.

[0039] Further, the molar ratio of bismaleimide, trimethylolpropane tris(3-mercaptopropionate), and catalyst triethylamine is 1:(2.2-2.5):(0.05-0.10);

[0040] The ratio of maleimide to chloroform is 30 g / 100 mL.

[0041] Further, the molar ratio of maleimide mercaptopropionate to allyl glycidyl ether is 1:(4.0-4.2);

[0042] The photoinitiator is photoinitiator 184, and the amount used is 1% to 5% of the total mass of maleimide mercaptopropionate and allyl glycidyl ether;

[0043] The ratio of maleimidothiopropionate to chloroform was 15 g / 100 mL.

[0044] Furthermore, the bismaleimide is one of N,N'-cyclohexanebismaleimide, disulfide-bismaleimidoethane, 1,10-bis(maleimido)decane, 1,8-bis(maleimido)diethylene glycol, 1,11-bis(maleimido)triethylene glycol, 1,23-bis(maleimido)heptanediol, bismaleimide-diethylene glycol, N,N'-tetramethylenebismaleimide, and N,N'-(4,4'-methylenediphenyl)bismaleimide 358.

[0045] In the above technical scheme, bismaleimide is mixed with trimethylolpropane tris(3-mercaptopropionate), and under the action of heat, the double bond in bismaleimide reacts with the thiol group in trimethylolpropane tris(3-mercaptopropionate), so that the prepared bismaleimide mercaptopropionate has a polythiol structure; then it reacts with the allyl group in allyl glycidyl ether, and introduces polyepoxy groups at the end group of the bismaleimide compound. By controlling the amount of substance, the prepared bismaleimide glycidyl ether contains four groups of epoxy groups. 2,4-dihydroxybenzophenone is mixed with epichlorohydrin, and under the action of alkali, the 4-hydroxy structure in 2,4-dihydroxybenzophenone reacts with the chlorine group in epichlorohydrin to obtain epoxybenzophenone; then under the action of alkali solution, the epoxy group is ring-opened to form two hydroxyl groups, thereby obtaining benzophenone diol.

[0046] Under the action of tetrabutylammonium bromide, an epoxy compound containing bismaleimide (bismaleimide glycidyl ether) and a diol containing a benzophenone group (benzophenone diol) are mixed to make a ring-opening reaction with a hydroxyl group to prepare a branched epoxy resin. In the branched epoxy resin, the introduced maleimide functional group can effectively improve the mechanical properties and heat resistance of the epoxy resin cured product and the polypropylene board prepared therefrom. The introduction of the benzophenone group can improve the sensitivity of the polypropylene board to ultraviolet light and improve its weather resistance; and can inhibit the ring-opening of the maleimide structure, so that it maintains the enhanced characteristics, so that the prepared polypropylene board can obtain higher mechanical properties and thermal stability; the interface performance of the epoxy resin cured product with glass fiber and polypropylene board can also be effectively enhanced.

[0047] Furthermore, the mixing process conditions are: temperature 100-120°C, duration 20-30 min;

[0048] The process conditions for extrusion are: temperature 190-210°C, screw speed 180-200rpm;

[0049] The composite process conditions are: temperature 190-200°C, pressure 0.25-2.5MPa.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. The high-strength polypropylene hollow plastic plate and its preparation method described in the present invention obtain good mechanical properties by forming a polypropylene hollow plastic plate with a panel and a core layer having a hollow structure. Branched epoxy resin and bisphenol A epoxy resin are compounded and added to the material system of the polypropylene hollow plastic plate to form an interpenetrating network, which increases the entanglement and cross-linking between system molecules, thereby enhancing the melt strength and helping to improve the mechanical properties and heat resistance, UV resistance and other properties of the prepared polypropylene hollow plastic plate.

[0052] 2. The high-strength polypropylene hollow plastic plate and its preparation method described in the present invention are prepared by the reaction of bismaleimide glycidyl ether and benzophenone diol through branched epoxy resin. The introduced maleimide and benzophenone groups enable the polypropylene hollow plastic plate to obtain higher mechanical properties, reduce sensitivity to ultraviolet light, and improve weather resistance and heat resistance. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] In the following specific implementations,

[0055] Polypropylene: Dongming 500N, Jiutai L5E89, from Suqian Qinfa Plastic Products Technology Co., Ltd.;

[0056] Maleic anhydride grafted polypropylene: PO 1020, from ExxonMobil Chemical Company;

[0057] Calcium carbonate: average particle size 40-50nm, sourced from Shanxi Xintai Hengxin Nanomaterials Co., Ltd.

[0058] Talc: HAR T84, from Yiruishi (Shanghai) Investment Management Co., Ltd.

[0059] Glass fiber: length 3-6mm, SiO2 content > 95.0%, sourced from Changzhou Qiushuo Chemicals Co., Ltd.

[0060] The coupling agent is KH-550; the antioxidants are antioxidant 1010 and antioxidant 168, with a mass ratio of 2:1;

[0061] The phenolic epoxy resin is o-cresol epoxy resin, brand NPCN-704, NPCN-638, mass ratio is 9:1, sourced from Guangzhou Ye Zeng Chemical Co., Ltd.;

[0062] The curing agent is dicyandiamide (DICY-P), which comes from Gaide Chemical;

[0063] The accelerator was 2-ethyl-4-methylimidazole (2E4MZ), which was sourced from Gaide Chemical;

[0064] The polypropylene hollow plastic plate includes 2 groups of face plates and 1 group of core layers; the thickness of the polypropylene hollow plastic plate is 10 mm; the thickness of the face plates is 3 mm; the thickness of the core layer is 7 mm, and the cross-sectional structure is a hollow circle with a circle diameter of 8 mm and a wall thickness of 0.32 mm, which is formed by rolling with an extrusion roller;

[0065] The "parts" mentioned below are all parts by mass.

[0066] Embodiment 1: A method for preparing a high-strength polypropylene hollow plastic plate, comprising the following process:

[0067] Step (1), 1.1. Mix 2,4-dihydroxybenzophenone and 2M sodium hydroxide aqueous solution, stir to dissolve, add epichlorohydrin under nitrogen atmosphere, heat to 90°C for 4h; wash with water at 80°C, dry the organic phase, filter, distill under reduced pressure, recrystallize with ethanol, and dry in vacuo to obtain epoxybenzophenone; the molar ratio of 2,4-dihydroxybenzophenone to epichlorohydrin is 1:2.5; the ratio of 2,4-dihydroxybenzophenone to sodium hydroxide aqueous solution is 0.2 mol / 100mL;

[0068] Mix epoxy benzophenone and 30 wt% potassium hydroxide aqueous solution, heat to 80°C, and react for 10 hours; add dichloromethane, separate the liquids, wash the organic phase with water, dry it, distill it under reduced pressure, and dry it in vacuum to obtain benzophenone diol; the ratio of epoxy benzophenone to potassium hydroxide aqueous solution is 30 g / 10 mL;

[0069] 1.2. Mix 30 g of N, N'-tetramethylene bismaleimide, trimethylolpropane tris(3-mercaptopropionate) and a catalyst in 100 mL of chloroform, heat to 58 ° C under a nitrogen atmosphere, and stir to react for 150 min; distill under reduced pressure, wash, and dry to obtain bismaleimide mercaptopropionate;

[0070] 30 g of maleimide mercaptopropionate, allyl glycidyl ether, and 1% of photoinitiator 184 were mixed in 200 mL of chloroform, and subjected to ultraviolet irradiation for 4 h; distilled under reduced pressure, washed, and dried to obtain bismaleimide glycidyl ether;

[0071] The molar ratio of N,N'-tetramethylenebismaleimide, trimethylolpropane tris(3-mercaptopropionate), and catalyst triethylamine is 1:2.2:0.05; the mass ratio of maleimide mercaptopropionate and allyl glycidyl ether is 10:4.4;

[0072] 1.3. Under nitrogen atmosphere, 10 parts of benzophenone diol, 54 parts of bismaleimide glycidyl ether and 0.8 parts of tetrabutylammonium bromide were mixed, stirred and heated to 80°C, and kept warm for 24 hours; cooled to room temperature, tetrahydrofuran was added to dissolve, deionized water was added to separate layers, rotary evaporated, and vacuum dried to obtain a branched epoxy resin;

[0073] Step (2), 100 parts of polypropylene, 10 parts of maleic anhydride grafted polypropylene, 6 parts of talc, 10 parts of calcium carbonate, 4 parts of glass fiber, 0.5 parts of coupling agent, 5 parts of epoxy resin (the mass ratio of bisphenol A epoxy resin to branched epoxy resin is 2:1), 0.1 parts of curing agent and 0.5 parts of antioxidant are mixed (temperature 100°C, time length 30min), extruded (temperature 190°C, screw speed 180rpm), pulled and stretched to form a panel and a core layer respectively, and compounded (temperature 190°C, pressure 0.35MPa) to obtain a polypropylene hollow plastic plate.

[0074] Embodiment 2: A method for preparing a high-strength polypropylene hollow plastic plate, comprising the following process:

[0075] Step (1), 1.1. Mix 2,4-dihydroxybenzophenone and 2M sodium hydroxide aqueous solution, stir to dissolve, add epichlorohydrin under nitrogen atmosphere, heat to 92°C for reaction for 3.5h; wash with water at 80°C, dry the organic phase, filter, distill under reduced pressure, recrystallize with ethanol, and dry in vacuo to obtain epoxybenzophenone; the molar ratio of 2,4-dihydroxybenzophenone to epichlorohydrin is 1:2.9; the ratio of 2,4-dihydroxybenzophenone to sodium hydroxide aqueous solution is 0.2mol / 100mL;

[0076] Mix epoxy benzophenone and 30 wt% potassium hydroxide aqueous solution, heat to 82°C, and react for 9.5 hours; add dichloromethane, separate the liquids, wash the organic phase with water, dry it, distill it under reduced pressure, and dry it in vacuum to obtain benzophenone diol; the ratio of epoxy benzophenone to potassium hydroxide aqueous solution is 30 g / 10 mL;

[0077] 1.2. Mix 30g of 1,11-bis(maleimido)triethylene glycol, trimethylolpropane tris(3-mercaptopropionate) and a catalyst in 100mL of chloroform, heat to 60°C under nitrogen atmosphere, and stir to react for 120min; distill under reduced pressure, wash, and dry to obtain bismaleimide mercaptopropionate;

[0078] 30 g of maleimide mercaptopropionate, allyl glycidyl ether, and 3% of photoinitiator 184 were mixed in 200 mL of chloroform, and subjected to ultraviolet irradiation for 4.5 h; distilled under reduced pressure, washed, and dried to obtain bismaleimide glycidyl ether;

[0079] The molar ratio of 1,11-bis(maleimido)triethylene glycol, trimethylolpropane tris(3-mercaptopropionate), and catalyst triethylamine is 1:2.4:0.08; the mass ratio of maleimide mercaptopropionate and allyl glycidyl ether is 10:4.1;

[0080] 1.3. Under nitrogen atmosphere, 10 parts of benzophenone diol, 58 parts of bismaleimide glycidyl ether and 0.9 parts of tetrabutylammonium bromide were mixed, stirred and heated to 85°C, and kept warm for 24 hours; cooled to room temperature, tetrahydrofuran was added to dissolve, deionized water was added to separate layers, rotary evaporated, and vacuum dried to obtain a branched epoxy resin;

[0081] Step (2), 93 parts of polypropylene, 12 parts of maleic anhydride grafted polypropylene, 7 parts of talc, 12 parts of calcium carbonate, 5 parts of glass fiber, 0.8 parts of coupling agent, 15 parts of epoxy resin (the mass ratio of bisphenol A epoxy resin to branched epoxy resin is 1:1), 2.5 parts of curing agent and 0.8 parts of antioxidant are mixed (temperature 110°C, time 25min), extruded (temperature 200°C, screw speed 190rpm), pulled and stretched to form a panel and a core layer respectively, and compounded (195°C, pressure 0.30MPa) to obtain a polypropylene hollow plastic plate.

[0082] Embodiment 3: A method for preparing a high-strength polypropylene hollow plastic plate, comprising the following process:

[0083] Step (1), 1.1. Mix 2,4-dihydroxybenzophenone and 2M sodium hydroxide aqueous solution, stir to dissolve, add epichlorohydrin under nitrogen atmosphere, heat to 95°C for reaction for 3h; wash with water at 80°C, dry the organic phase, filter, distill under reduced pressure, recrystallize with ethanol, and dry in vacuo to obtain epoxybenzophenone; the molar ratio of 2,4-dihydroxybenzophenone to epichlorohydrin is 1:3.2; the ratio of 2,4-dihydroxybenzophenone to sodium hydroxide aqueous solution is 0.2 mol / 100mL;

[0084] Mix epoxy benzophenone and 30 wt% potassium hydroxide aqueous solution, heat to 85°C, and react for 9 hours; add dichloromethane, separate the liquids, wash the organic phase with water, dry it, distill it under reduced pressure, and dry it in vacuum to obtain benzophenone diol; the ratio of epoxy benzophenone to potassium hydroxide aqueous solution is 30 g / 10 mL;

[0085] 1.2. Mix 30 g of bismaleimide-diethylene glycol, trimethylolpropane tris(3-mercaptopropionate) and a catalyst in 100 mL of chloroform, heat to 62 ° C under a nitrogen atmosphere, and stir to react for 100 min; distill under reduced pressure, wash, and dry to obtain bismaleimide mercaptopropionate;

[0086] 30 g of maleimide mercaptopropionate, allyl glycidyl ether, and 5% of photoinitiator 184 were mixed in 200 mL of chloroform, and subjected to ultraviolet irradiation for 5 h; distilled under reduced pressure, washed, and dried to obtain bismaleimide glycidyl ether;

[0087] The molar ratio of bismaleimide-diethylene glycol, trimethylolpropane tris(3-mercaptopropionate), and catalyst triethylamine is 1:2.5:0.10; the molar ratio of maleimide mercaptopropionate and allyl glycidyl ether is 10:3.8;

[0088] 1.3. Under nitrogen atmosphere, 10 parts of benzophenone diol, 61 parts of bismaleimide glycidyl ether and 1.0 part of tetrabutylammonium bromide were mixed, stirred and heated to 90°C, and kept warm for 24 hours; cooled to room temperature, tetrahydrofuran was added to dissolve, deionized water was added to separate layers, rotary evaporated, and vacuum dried to obtain a branched epoxy resin;

[0089] Step (2), 85 parts of polypropylene, 15 parts of maleic anhydride grafted polypropylene, 8 parts of talc, 15 parts of calcium carbonate, 7 parts of glass fiber, 1.0 part of coupling agent, 25 parts of epoxy resin (the mass ratio of bisphenol A epoxy resin to branched epoxy resin is 1:2), 5.0 parts of curing agent and 1.0 part of antioxidant are mixed (temperature 120°C, time 20min), extruded (temperature 210°C, screw speed 200rpm), pulled and pulled to form a panel and a core layer respectively, and compounded (temperature 200°C, pressure 0.27MPa) to obtain a polypropylene hollow plastic plate.

[0090] Comparative Example 1: A method for preparing a high-strength polypropylene hollow plastic plate, comprising the following processes:

[0091] Step (1), 30g of N,N'-tetramethylenebismaleimide, trimethylolpropane tris(3-mercaptopropionate) and a catalyst are mixed in 100mL of chloroform, heated to 58°C under a nitrogen atmosphere, and stirred for reaction for 150min; distilled under reduced pressure, washed, and dried to obtain bismaleimide mercaptopropionate;

[0092] 30 g of maleimide mercaptopropionate, allyl glycidyl ether, and 1% of photoinitiator 184 were mixed in 200 mL of chloroform, and subjected to ultraviolet irradiation for 4 h; distilled under reduced pressure, washed, and dried to obtain bismaleimide glycidyl ether;

[0093] The molar ratio of N,N'-tetramethylenebismaleimide, trimethylolpropane tris(3-mercaptopropionate), and catalyst triethylamine is 1:2.2:0.05; the mass ratio of maleimide mercaptopropionate and allyl glycidyl ether is 10:4.4;

[0094] Under nitrogen atmosphere, 4.2 parts of 1,5-pentanediol, 54 parts of bismaleimide glycidyl ether and 0.8 parts of tetrabutylammonium bromide were mixed, stirred and heated to 80°C, and kept warm for 24 hours; cooled to room temperature, tetrahydrofuran was added to dissolve, deionized water was added to separate layers, rotary evaporated, and vacuum dried to obtain a branched epoxy resin;

[0095] Step (2) is the same as in Example 1 to obtain a polypropylene hollow plastic plate.

[0096] Comparative Example 2: A method for preparing a high-strength polypropylene hollow plastic plate, comprising the following processes:

[0097] Step (1), taking 2,4-dihydroxybenzophenone and 2M sodium hydroxide aqueous solution, mixing, stirring and dissolving, adding epichlorohydrin under nitrogen atmosphere protection, heating to 90°C for reaction for 4h; washing with water at 80°C, taking the organic phase to dry, filtering, distilling under reduced pressure, recrystallizing with ethanol, and vacuum drying to obtain epoxybenzophenone; the molar ratio of 2,4-dihydroxybenzophenone to epichlorohydrin is 1:2.5; the ratio of 2,4-dihydroxybenzophenone to sodium hydroxide aqueous solution is 0.2mol / 100mL;

[0098] Mix epoxy benzophenone and 30 wt% potassium hydroxide aqueous solution, heat to 80°C, and react for 10 hours; add dichloromethane, separate the liquids, wash the organic phase with water, dry it, distill it under reduced pressure, and dry it in vacuum to obtain benzophenone diol; the ratio of epoxy benzophenone to potassium hydroxide aqueous solution is 30 g / 10 mL;

[0099] Under the protection of nitrogen atmosphere, 10 parts of benzophenone diol, 16.6 parts of bisphenol A epoxy diacrylate and 0.8 parts of tetrabutylammonium bromide were mixed, stirred and heated to 80°C, and kept warm for reaction for 24 hours; cooled to room temperature, tetrahydrofuran was added to dissolve, deionized water was added to separate layers, rotary evaporated, and vacuum dried to obtain a modified epoxy resin;

[0100] Step (2), 100 parts of polypropylene, 10 parts of maleic anhydride grafted polypropylene, 6 parts of talc, 10 parts of calcium carbonate, 4 parts of glass fiber, 0.5 parts of coupling agent, 5 parts of epoxy resin (the mass ratio of bisphenol A epoxy resin and modified epoxy resin is 2:1), 0.1 parts of curing agent and 0.5 parts of antioxidant are mixed (temperature 100°C, time length 30min), extruded (temperature 190°C, screw speed 180rpm), pulled and pulled to form a panel and a core layer respectively, and compounded (temperature 190°C, pressure 0.35MPa) to obtain a polypropylene hollow plastic plate.

[0101] Comparative Example 3: A method for preparing a high-strength polypropylene hollow plastic plate, comprising the following processes:

[0102] Step (2), 85-100 parts of polypropylene, 10-15 parts of maleic anhydride grafted polypropylene, 6-8 parts of talc, 10-15 parts of calcium carbonate, 4-7 parts of glass fiber, 0.5-1.0 parts of coupling agent, 5-25 parts of epoxy resin (the mass ratio of bisphenol A epoxy resin to phenolic epoxy resin is 2:1), 0.1-5.0 parts of curing agent and 0.5-1.0 parts of antioxidant are mixed (temperature 100°C, time length 30min), extruded (temperature 190°C, screw speed 180rpm), pulled and stretched to form a panel and a core layer respectively, and compounded (temperature 190°C, pressure 0.35MPa) to obtain a polypropylene hollow plastic plate.

[0103] Comparative Example 4: A method for preparing a polypropylene board, comprising the following processes:

[0104] 100 parts of polypropylene, 10 parts of maleic anhydride grafted polypropylene, 6 parts of talc (BHS-1250A, sourced from Quanzhou Xufeng Powder Raw Material Co., Ltd.), 10 parts of calcium carbonate, 0.5 parts of coupling agent and 0.5 parts of antioxidant were mixed (temperature 100°C, time 30 min), extruded (temperature 190°C, screw speed 180rpm), pulled and stretched to form a panel and a core layer respectively, and compounded (temperature 190°C, pressure 0.35MPa) to obtain a polypropylene hollow plastic plate.

[0105] Experiment: Take the polypropylene hollow plastic plates obtained in Examples 1-3 and Comparative Examples 1-4, prepare samples, test their properties respectively and record the test results:

[0106] Flat compression performance test: Based on GB / T 1453 as the reference standard, an electronic universal material testing machine is used to test the static compression performance of the sample, and the loading rate is 1mm / min; before the experiment, the sample is placed at 23℃ and 50RH% for 24h;

[0107] Bending performance test: GB / T 1456 is used as the reference standard to test the bending performance of the sample, with a loading rate of 2mm / min;

[0108] Anti-ultraviolet performance test: place the sample under ultraviolet light for 28 days, including standard irradiation for 8 hours and standard condensation for 4 hours, and a cycle of 12 hours. Test its bending performance again and calculate its bending strength retention rate.

[0109] Thermal stability test: Place the sample at 60°C for 3 hours, measure its dimensional change rate, and detect the dimensional stability of the sample.

[0110] Flat compressive strength (MPa) Bending strength(MPa) UV aging retention rate (%) Dimensional change rate (%) Example 1 3.5 21.3 101.9 0.04 Example 2 3.7 22.4 103.0 0.03 Example 3 4.0 23.7 104.5 0.01 Comparative Example 1 3.3 19.8 95.1 0.12 Comparative Example 2 2.9 17.2 100.4 0.15 Comparative Example 3 3.2 18.5 93.8 0.20 Comparative Example 4 1.5 10.5 88.2 0.32

[0111] According to the data in the above table, we can clearly draw the following conclusions:

[0112] The polypropylene hollow plastic plates obtained in Examples 1-3 are compared with the polypropylene hollow plastic plates obtained in Comparative Examples 1-4. The test results show that:

[0113] Compared with the comparative example, the polypropylene hollow plastic plates obtained in Examples 1-3 have higher flat compression strength, bending strength and anti-ultraviolet retention rate data, which fully demonstrates that the present invention achieves the improvement of the mechanical strength and anti-ultraviolet performance of the polypropylene hollow plastic plate.

[0114] Compared with Example 1, in Comparative Example 1, benzophenone diol is replaced by 1,5-pentanediol; in Comparative Example 2, bismaleimide glycidyl ether is replaced by bisphenol A epoxy diacrylate; in Comparative Example 3, branched epoxy resin is replaced by phenolic epoxy resin; and in Comparative Example 4, no component epoxy resin is added. Compared with Example 1, the flat compression strength, bending strength and anti-ultraviolet retention rate data of the polypropylene hollow plastic plates obtained in Comparative Examples 1-4 are reduced. It can be seen that the arrangement of the components and processes of the polypropylene hollow plastic plates of the present invention can promote the improvement of its mechanical strength and anti-ultraviolet performance.

[0115] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process method article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process method article or device.

[0116] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-strength polypropylene hollow plastic plate, characterized in that: Including the following processes: The polypropylene, maleic anhydride grafted polypropylene, filler, epoxy resin, curing agent and additive are mixed, extruded, pulled and formed into a panel and a core layer respectively; the panel and the core layer are compounded to obtain a polypropylene hollow plastic plate; The epoxy resin is at least a mixture of a branched epoxy resin and a bisphenol A epoxy resin; The branched epoxy resin is prepared by the following process: Under the protection of nitrogen atmosphere, benzophenone diol, bismaleimide glycidyl ether and tetrabutylammonium bromide were mixed, stirred and heated to 80-90° C., and kept warm for 24 hours to obtain branched epoxy resin.

2. The method for preparing a high-strength polypropylene hollow plastic plate according to claim 1, characterized in that: The benzophenone diol is prepared by the following process: Take 2,4-dihydroxybenzophenone and sodium hydroxide aqueous solution, mix them, stir and dissolve them, add epichlorohydrin under nitrogen atmosphere, raise the temperature to 90-95°C and react for 3-4h to obtain epoxybenzophenone; Mix epoxy benzophenone and potassium hydroxide aqueous solution, heat to 80-85° C., and react for 9-10 hours to obtain benzophenone diol.

3. The method for preparing a high-strength polypropylene hollow plastic plate according to claim 1, characterized in that: The bismaleimide glycidyl ether is prepared by the following process: Mix bismaleimide, trimethylolpropane tris(3-mercaptopropionate) and a catalyst in chloroform, raise the temperature to 58-62° C. under nitrogen atmosphere protection, and stir to react for 100-150 minutes to obtain bismaleimide mercaptopropionate; Bismaleimide mercaptopropionate, allyl glycidyl ether and a photoinitiator are mixed in chloroform and subjected to ultraviolet irradiation for 4 to 5 hours to obtain bismaleimide glycidyl ether.

4. The method for preparing a high-strength polypropylene hollow plastic plate according to claim 1, characterized in that: The polypropylene hollow plastic plate comprises the following components: by mass, 85-100 parts of polypropylene, 10-15 parts of maleic anhydride grafted polypropylene, 20-30 parts of filler, 5-25 parts of epoxy resin, 0.1-5.0 parts of curing agent, and 1.0-2.0 parts of auxiliary agent.

5. The method for preparing a high-strength polypropylene hollow plastic plate according to claim 4, characterized in that: The filler comprises 6 to 8 parts of talc powder, 10 to 15 parts of calcium carbonate and 4 to 7 parts of glass fiber.

6. The method for preparing a high-strength polypropylene hollow plastic plate according to claim 1, characterized in that: The branched epoxy resin is prepared from the following components by mass: 10 parts of benzophenone diol, 54-61 parts of bismaleimide glycidyl ether and 0.8-1.0 parts of tetrabutylammonium bromide.

7. The method for preparing a high-strength polypropylene hollow plastic plate according to claim 1, characterized in that: The polypropylene hollow plastic plate comprises 2 to 3 groups of face panels, and a core layer is arranged between two adjacent groups of face panels; the thickness of the polypropylene hollow plastic plate is 4 to 15 mm; the thickness of the face panel is 1 to 5 mm, and the thickness of the core layer is 2 to 10 mm.

8. A high-strength polypropylene hollow plastic plate prepared according to the preparation method according to any one of claims 1 to 7.