Reed-based foamed wood-plastic co-extruded wood-grain-like shell material and preparation method thereof

Abstract

The invention provides a reed-based foamed wood-plastic co-extruded wood-grain-like shell material. The high-mesh and low-mesh reed fiber powder is adopted, so that the toughness of the material is improved, the use ratio of the reed powder is increased, the density is reduced, and the material cost is reduced; meanwhile, the nano calcium carbonate and the surface modifier are added to modify the surface of the reed fiber, so that the purpose of inorganic and organic activation and modification comprehensive effects is achieved, the interfacial compatibility with plastic is improved, and meanwhile, the preparation raw materials contain sodium lignin sulfonate similar to an adhesive substance, so that the plastic has good mechanical properties. The interfacial compatibility of the reed powder and unsaturated olefin resin can be promoted. By selecting a reasonable formula and a proper processing technology, the interfacial compatibility of the material is greatly improved, and the mechanical property and the aging resistance are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite materials, and particularly relates to a reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material and a preparation method thereof. BACKGROUND

[0002] Wood-plastic co-extrusion composite material is a kind of high polymer composite material with excellent performance emerging in recent years. It has the dual advantages of wood and plastic, not only has the characteristics of aging resistance, water resistance, easy cleaning, but also has the characteristics of easy installation and processing, and reusability. However, this material generally has a problem, that is, the poor interface compatibility between reed powder and plastic, low strength, large density, and single pattern, which is also a research direction for a long time.

[0003] Therefore, it is necessary to provide a reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material which is light in weight, high in strength, aging resistant, and wood-grain-imitating. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to provide a reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material and a preparation method thereof. The reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material provided by the present application has the characteristics of light weight, high strength, aging resistance, and wood-grain-imitating effect.

[0005] The present application provides a reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material. The preparation raw materials include: two kinds of reed powder particles with different mesh numbers, unsaturated olefin resin, nano calcium carbonate, surface modifier, sodium lignosulfonate, glass fiber, shell powder, and additive; the surface modifier is selected from at least one of stearic acid, silane coupling agent, titanate coupling agent, and sodium dodecyl benzene sulfonate.

[0006] Preferably, the additive is selected from at least one of foaming agent, lubricant, antioxidant, preservative, compatibility agent, composite ultraviolet absorption agent, and wood-grain-imitating color master batch.

[0007] Preferably, the preparation raw materials of the surface layer include: high-mesh-number reed powder particles 20-30 parts, unsaturated olefin resin 25-35 parts, shell powder 3-5 parts, sodium lignosulfonate 5-10 parts, nano calcium carbonate 1-2 parts, lubricant 2-2.5 parts, surface modifier 0.1-0.2 parts, antioxidant 0.2-0.4 parts, preservative 2-5 parts, compatibility agent 2-2.5 parts, composite ultraviolet absorption agent 0.2-0.4 parts, and wood-grain-imitating color master batch 2-3 parts.

[0008] Preferably, the preparation raw materials of the surface layer include: high-mesh-number reed powder particles 20-30 parts, unsaturated olefin resin 25-35 parts, shell powder 3-5 parts, sodium lignosulfonate 5-10 parts, nano calcium carbonate 1-2 parts, lubricant 2-2.5 parts, surface modifier 0.1-0.2 parts, antioxidant 0.2-0.4 parts, preservative 2-5 parts, compatibility agent 2-2.5 parts, composite ultraviolet absorption agent 0.2-0.4 parts, and wood-grain-imitating color master batch 2-3 parts.

[0009] Preferably, the high-mesh-number reed powder particles are 60-mesh-100-mesh reed powder, and the water content is less than or equal to 4%.

[0010] The raw materials for preparing the core layer, by weight, include: 50-70 parts of low-mesh reed powder particles, 25-35 parts of unsaturated olefin resin, 2-3 parts of foaming agent, 5-10 parts of glass fiber, 5-10 parts of shell powder, 5-10 parts of sodium lignosulfonate, 1-2 parts of nano calcium carbonate, 2-2.5 parts of lubricant, 0.1-0.2 parts of surface modifier, and 2-2.5 parts of compatibilizer;

[0011] The low-mesh reed powder particles are 30-60 mesh reed powder with a moisture content of less than or equal to 4%.

[0012] Preferably, the unsaturated olefin resin is selected from at least two of high-density polyethylene resin, low-density polyethylene resin, and polypropylene resin;

[0013] The melt index of the unsaturated olefin resin is 0.5 to 2.0 g / min.

[0014] Preferably, the composite UV absorber is selected from two or more of the following: phenyl benzoate, 2-hydroxy-4-n-octyloxybenzophenone, resorcinol monobenzoate, tris(1,2,2,6,6-pentamethylpiperidinyl)phosphite, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and hexamethylphosphoric acid triamine.

[0015] Preferably, the foaming agent is one of azodicarbonamide and 4,4-disulfonylhydrazine diphenyl ether;

[0016] The antioxidant is antioxidant 1010;

[0017] The lubricant is EBS;

[0018] The compatibilizer is maleic anhydride-grafted PE.

[0019] The preservative is zinc borate;

[0020] The shell powder has a mesh size of 200 to 800 mesh;

[0021] The nano-calcium carbonate has a particle size of 20nm to 100nm;

[0022] The glass fiber has a length of 3 to 6 mm.

[0023] The present invention also provides a method for preparing the above-mentioned reed-based foamed wood-plastic co-extruded imitation wood grain shell material, comprising the following steps:

[0024] a) Preparation of surface granulated material:

[0025] a1) unsaturated olefin resin, shell powder, lubricant, antioxidant, compatibilizer, preservative, composite ultraviolet absorption agent and wood grain color masterbatch are mixed and dried according to the proportion of the surface layer material formula to obtain raw material A;

[0026] High-mesh reed powder particles, sodium lignosulfonate, and nano-calcium carbonate are mixed and dried, and then a surface modifier is added to obtain raw material B;

[0027] a2) Raw material A is mixed and stirred, raw material B is added after heating, mixed and stirred, and then cooled to obtain a mixture;

[0028] a3) The mixture is granulated to obtain surface layer material granules;

[0029] b) Preparation of core layer material granules

[0030] b1) unsaturated olefin resin, foaming agent, shell powder, lubricant, and compatibilizer are mixed and dried according to the proportion of the core layer material formula to obtain raw material C;

[0031] Low-mesh reed powder particles, glass fibers, sodium lignosulfonate, and nano-calcium carbonate are mixed and dried according to the proportion of the core layer material formula, and then a surface modifier is added to obtain raw material D;

[0032] b2) Raw material C is mixed and stirred, raw material D is added after heating, mixed and stirred, and then cooled to obtain a mixture;

[0033] b3) The mixture is granulated to obtain core layer material granules;

[0034] c) The surface layer material granules and the core layer material granules are respectively extruded to form a co-extruded composite material;

[0035] d) The co-extruded composite material is cooled and formed, and then cut to obtain a reed-based foamed wood-plastic co-extruded wood grain shell material.

[0036] Preferably, in step a2), the mixing and stirring speed is 25-35 r / min, the time is 15-20 min, and the temperature is 50-80°C;

[0037] In step a3), the granulation parameters are: the temperature of the parallel twin-screw extruder is 150-180°C, the main machine speed is 70-90 r / min, and the feeding speed is 20-30 r / min.

[0038] Preferably, in step b2), the mixing and stirring speed is 25-35 r / min, the time is 15-20 min, and the temperature is 50-80°C;

[0039] In step b3), the parameters of the granulation are as follows: the temperature of the parallel twin-screw extruder is 150-180 DEG C, the rotating speed of the main machine is 70-90 r / min, and the rotating speed of the feeding machine is 20-30 r / min.

[0040] Preferably, step c) comprises the following steps:

[0041] The surface layer material granules and the core layer material granules are respectively added into a single-screw extruder and a conical twin-screw extruder, and then are extruded at high temperature in a co-extrusion die to obtain a molded co-extrusion plastic composite material.

[0042] The heating cylinder temperature of the conical twin-screw extruder is 160-200 DEG C, the temperature of the converging core is 150-165 DEG C, the temperature of the die is 150-180 DEG C, the rotating speed of the main machine is 5-20 r / min, the rotating speed of the feeding machine is 5-10 r / min, the pressure is 20-40 MPa, and the current of the main machine is controlled to be 30 A-45 A.

[0043] Compared with the prior art, the reed-based foamed wood-plastic co-extrusion wood-grain-like shell material provided by the application has the following advantages: the high and low mesh reed fiber powder is used to increase the material toughness, improve the use proportion of the reed powder, reduce the density, and reduce the material cost; the nano calcium carbonate and the surface modifier are added to modify the surface of the reed fiber, and the inorganic and organic activation modification comprehensive effect is achieved, the interface compatibility with the plastic is increased, the lignin sulfonate which is similar to the adhesive substance is contained in the preparation raw material, and the interface compatibility of the reed powder and the unsaturated olefin resin is promoted. The reasonable formula and the appropriate processing technology are selected, the interface compatibility of the material is greatly improved, and the mechanical properties and the aging resistance are significantly improved.

[0044] Results show that the reed-based foamed wood-plastic co-extrusion wood-grain-like shell material provided by the application has the following properties: the static bending strength is 55-65 MPa, the elastic modulus is 5500-7200 MPa, the formaldehyde release amount is 0.1-0.3 mg / L, and the 24 h water absorption expansion rate is 0.2-0.4%. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The process flow chart of the preparation method of the reed-based foamed wood-plastic co-extrusion wood-grain-like shell material provided by the application is shown in the figure.

[0046] Figure 2The scanning electron microscope image of the reed-based foamed wood-plastic co-extrusion wood grain shell material core layer prepared in Example 1 of the present application;

[0047] Figure 3 The scanning electron microscope image of the reed-based foamed wood-plastic co-extrusion wood grain shell material core layer prepared in Example 1 of the present application;

[0048] Figure 4 The scanning electron microscope image of the reed-based foamed wood-plastic co-extrusion wood grain shell material core layer prepared in Example 1 of the present application;

[0049] Figure 5 The scanning electron microscope image of the reed-based foamed wood-plastic co-extrusion wood grain shell material surface layer prepared in Example 1 of the present application;

[0050] Figure 6 The scanning electron microscope image of the reed-based foamed wood-plastic co-extrusion wood grain shell material surface layer prepared in Example 1 of the present application;

[0051] Figure 7 The infrared spectrum of the reed-based foamed wood-plastic co-extrusion wood grain shell material surface layer prepared in Example 1 and Comparative Example 3 of the present application. DETAILED DESCRIPTION

[0052] The present application provides a reed-based foamed wood-plastic co-extrusion wood grain shell material, the preparation raw materials comprising: two different mesh reed powder particles, unsaturated olefin resin, nano calcium carbonate, surface modifier, sodium lignosulfonate, glass fiber, shell powder and additive; the surface modifier is selected from at least one of stearic acid, silane coupling agent, titanate coupling agent, sodium dodecyl benzene sulfonate.

[0053] In the present application, the additive is selected from at least one of foaming agent, lubricant, antioxidant, preservative, compatibility agent, composite ultraviolet absorption agent and wood grain color master batch.

[0054] In some embodiments of the present application, the reed-based foamed wood-plastic co-extrusion wood grain shell material is characterized by comprising a core layer and a surface layer compounded on the surface of the core layer.

[0055] The preparation raw materials of the surface layer comprise, in parts by mass: 20-30 parts of high-mesh reed powder particles, 25-35 parts of unsaturated olefin resin, 3-5 parts of shell powder, 5-10 parts of sodium lignosulfonate, 1-2 parts of nano calcium carbonate, 2-2.5 parts of lubricant, 0.1-0.2 parts of surface modifier, 0.2-0.4 parts of antioxidant, 2-5 parts of preservative, 2-2.5 parts of compatibility agent, 0.2-0.4 parts of composite ultraviolet absorption agent and 2-3 parts of wood grain color master batch.

[0056] The high-mesh reed powder particles are 60-100 mesh reed powder with a water content of less than or equal to 4%.

[0057] The raw material for preparing the surface layer according to the present application comprises 20-30 parts of high-mesh reed powder particles, which can be 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, or any value between 20 and 30 parts. The high-mesh reed powder particles are 60-mesh-100-mesh reed powder with a water content of less than or equal to 4%.

[0058] The raw material for preparing the surface layer according to the present application further comprises 25-35 parts of unsaturated olefin resin, which can be 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, or any value between 25 and 35 parts. The unsaturated olefin resin is selected from at least two of high-density polyethylene resin, low-density polyethylene resin, and polypropylene resin, preferably a combination of HDPE and polypropylene resin; and the melt index of the unsaturated olefin resin is 0.5-2.0 g / min, which can be 0.5, 1, 1.5, 2, or any value between 0.5 and 2.0 g / min.

[0059] The raw material for preparing the surface layer according to the present application further comprises 3-5 parts of shell powder, which can be 3, 3.5, 4, 4.5, 5, or any value between 3 and 5 parts. The shell powder has a mesh size of 200-800, which can be 200, 300, 400, 500, 600, 700, 800, or any value between 200 and 800.

[0060] The raw material for preparing the surface layer according to the present application further comprises 5-10 parts of sodium lignosulfonate, which can be 5, 6, 7, 8, 9, 10, or any value between 5 and 10 parts.

[0061] The raw material for preparing the surface layer according to the present application further comprises 1-2 parts of nano calcium carbonate, which can be 1, 1.5, 2, or any value between 1 and 2 parts. The nano calcium carbonate has a particle size of 20-100 nm, which can be 20, 40, 50, 60, 80, 100, or any value between 20 and 100 nm.

[0062] The raw material for preparing the surface layer according to the present application further comprises 2-2.5 parts of lubricant, which can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, or any value between 2 and 2.5 parts. The lubricant is ethylene bis-stearamide (EBS).

[0063] The preparation raw material of the surface layer provided by the present application further comprises 0.1-0.2 parts of a surface modifier in mass parts, which can be 0.1, 0.12, 0.14, 0.15, 0.17, 0.19, 0.2, or any value between 0.1 and 0.2. The surface modifier is selected from at least one of stearic acid, a silane coupling agent, a titanate coupling agent, and sodium dodecyl benzene sulfonate.

[0064] The preparation raw material of the surface layer provided by the present application further comprises 0.2-0.4 parts of an antioxidant in mass parts, which can be 0.2, 0.25, 0.3, 0.35, 0.4, or any value between 0.2 and 0.4. The antioxidant is antioxidant 1010.

[0065] The preparation raw material of the surface layer provided by the present application further comprises 2-5 parts of a preservative in mass parts, which can be 2, 3, 4, 5, or any value between 2 and 5. The preservative is zinc borate.

[0066] The preparation raw material of the surface layer provided by the present application further comprises 2-2.5 parts of a compatilizer in mass parts, which can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, or any value between 2 and 2.5. The compatilizer is maleic anhydride grafted PE.

[0067] The preparation raw material of the surface layer provided by the present application further comprises 0.2-0.4 parts of a composite ultraviolet absorption agent in mass parts, which can be 0.2, 0.25, 0.3, 0.35, 0.4, or any value between 0.2 and 0.4. The composite ultraviolet absorption agent is selected from two or more of phenyl o-hydroxybenzoate, 2-hydroxy-4-n-octyloxybenzophenone, m-phenylenediamine monobenzoate, tris(1,2,2,6,6-pentamethylpiperidyl) phosphite, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, and hexamethylphosphorus triamide. The present application adopts a composite ultraviolet absorption agent, which sufficiently ensures the aging resistance of the plastic composite material.

[0068] The preparation raw material of the surface layer provided by the present application further comprises 2-3 parts of wood grain color master batch in mass parts, which can be 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3, or any value between 2 and 3.

[0069] The preparation raw material of the core layer comprises, in mass parts, 50-70 parts of low-mesh reed powder particles, 25-35 parts of an unsaturated olefin resin, 2-3 parts of a foaming agent, 5-10 parts of glass fiber, 5-10 parts of shell powder, 5-10 parts of sodium lignosulfonate, 1-2 parts of nano calcium carbonate, 2-2.5 parts of a lubricant, 0.2 parts of a surface modifier, and 2-2.5 parts of a compatilizer.

[0070] The preparation raw material of the core layer provided by the present application includes 50-70 parts of low mesh reed powder particles in mass parts, which can be 50, 55, 60, 65, 70, or any value between 50-70 parts. The low mesh reed powder particles are 30-60 mesh reed powder, and the water content is less than or equal to 4%.

[0071] The preparation raw material of the core layer provided by the present application further includes 25-35 parts of unsaturated olefin resin in mass parts, which can be 25, 30, 35, or any value between 25-35 parts. The unsaturated olefin resin is selected from at least two of high-density polyethylene resin, low-density polyethylene resin, and polypropylene resin, preferably a combination of HDPE and polypropylene resin; and the melt index of the unsaturated olefin resin is 0.5-2.0 g / min, which can be 0.5, 1, 1.5, 2, or any value between 0.5-2.0 g / min.

[0072] The preparation raw material of the core layer provided by the present application further includes 2-3 parts of foaming agent in mass parts, which can be 2, 2.5, 3, or any value between 2-3 parts. The foaming agent is one of azodicarbonamide, 4,4-diazodicarbonamide diphenyl ether.

[0073] The preparation raw material of the core layer provided by the present application further includes 5-10 parts of glass fiber in mass parts, which can be 5, 6, 7, 8, 9, 10, or any value between 5-10 parts. The length of the glass fiber is 3-6 mm, which can be 3, 4, 5, 6, or any value between 3-6 mm.

[0074] The preparation raw material of the core layer provided by the present application further includes 5-10 parts of shell powder in mass parts, which can be 5, 6, 7, 8, 9, 10, or any value between 5-10 parts. The mesh of the shell powder is 200-800 mesh, which can be 200, 300, 400, 500, 600, 700, 800, or any value between 200-800 mesh.

[0075] The preparation raw material of the core layer provided by the present application further includes 5-10 parts of sodium lignosulfonate in mass parts, which can be 5, 6, 7, 8, 9, 10, or any value between 5-10 parts.

[0076] The preparation raw material of the core layer provided by the present application further includes 1-2 parts of nano calcium carbonate in mass parts, which can be 1, 1.5, 2, or any value between 1-2 parts. The nano calcium carbonate has a particle size of 20-100 nm, which can be 20, 40, 50, 60, 80, 100, or any value between 20-100 nm.

[0077] The preparation raw material of the core layer provided by the present application further comprises 2-2.5 parts of lubricant in mass parts, which can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, or any value between 2-2.5 parts. The lubricant is ethylene bis-stearamide (EBS).

[0078] The preparation raw material of the core layer provided by the present application further comprises 0.1-0.2 parts of surface modifier in mass parts, which can be 0.1, 0.12, 0.14, 0.15, 0.17, 0.19, 0.2, or any value between 0.1-0.2 parts. The surface modifier is at least one selected from stearic acid, silane coupling agent, titanate coupling agent, and sodium dodecyl benzene sulfonate.

[0079] The preparation raw material of the core layer provided by the present application further comprises 2-2.5 parts of compatibilizer in mass parts, which can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, or any value between 2-2.5 parts. The compatibilizer is maleic anhydride grafted PE.

[0080] The base used in the formula of the present application uses HDPE with excellent toughness, which can increase the use ratio of foaming agent, greatly reduce the density, and save cost; meanwhile, the formula contains lignin sulfonate sodium similar to adhesive substance, which can promote the interface compatibility of reed powder and high molecular PE; the added filler shell powder has good interface compatibility with plastic.

[0081] The present application also provides a preparation method of the above-mentioned reed-based foaming wood-plastic co-extrusion imitation wood grain shell material, which comprises the following steps:

[0082] a) preparing a surface layer material granule:

[0083] a1) mixing unsaturated olefin resin, shell powder, lubricant, antioxidant, compatibilizer, preservative, composite ultraviolet absorption agent, and imitation wood grain color master batch according to the formula proportion of the surface layer material, drying to obtain raw material A;

[0084] mixing high-mesh reed powder particles, lignin sulfonate sodium, and nano calcium carbonate according to the formula proportion of the surface layer material, drying, and then adding a surface modifier to obtain raw material B;

[0085] a2) mixing and stirring raw material A, adding raw material B after heating, mixing and stirring, and cooling to obtain a mixture;

[0086] a3) granulating the mixture to obtain a surface layer material granule;

[0087] b) preparing a core layer material granule

[0088] b1) mixing unsaturated olefin resin, foaming agent, shell powder, lubricant, and compatibilizer according to the formula proportion of the core layer material, drying to obtain raw material C;

[0089] The low mesh reed powder particles, glass fibers, sodium lignosulfonate and nano calcium carbonate are mixed and dried, and then a surface modifier is added to obtain raw material D;

[0090] b2) Mix and stir raw material C, add raw material D after heating, mix and stir, cool to obtain a mixture;

[0091] b3) Granulate the mixture to obtain core layer material granules;

[0092] c) Extrude the surface layer material granules and the core layer material granules respectively to obtain a co-extruded composite material;

[0093] d) Cool and shape the co-extruded composite material and cut to obtain a reed-based foamed wood-plastic co-extruded wood grain shell material.

[0094] Referring to Figure 1 , Figure 1 The process flow chart of the preparation method of the reed-based foamed wood-plastic co-extruded wood grain shell material provided by the present application.

[0095] The present application first prepares surface layer material granules and core layer material granules. The present application does not have special restrictions on the surface layer material granules and the core layer material granules.

[0096] In the preparation method of the surface layer material granules, in step a2), the mixing and stirring is carried out in a high-speed mixer, the rotating speed of the mixing and stirring is 25-35 r / min, which can be 25, 30, 35, or any value between 25-35 r / min, the time is 15-20 min, which can be 15, 16, 17, 18, 19, 20, or any value between 15-20 min, and the temperature is 50℃-80℃, which can be 50, 60, 70, 80, or any value between 50℃-80℃;

[0097] In step a3), the parameters of the granulation are as follows: the temperature of the parallel double screw extruder is 150℃-180℃, which can be 150, 160, 170, 180, or any value between 150℃-180℃; the rotating speed of the main machine is 70-90 r / min, which can be 70, 80, 90, or any value between 70-90 r / min, and the feeding rotating speed is 20-30 r / min.

[0098] In the preparation method of the core layer material granules, in step b2), the mixing and stirring is performed in a high-speed mixer, the rotating speed of the mixing and stirring is 25-35 r / min, which can be 25, 30, 35, or any value between 25-35 r / min, the time is 15-20 min, which can be 15, 16, 17, 18, 19, 20, or any value between 15-20 min, and the temperature is 50-80℃, which can be 50, 60, 70, 80, or any value between 50-80℃.

[0099] In step b3), the parameters of the granulation are as follows: the temperature of the parallel twin-screw extruder is 150-180℃, which can be 150, 160, 170, 180, or any value between 150-180℃; the rotating speed of the main machine is 70-90 r / min, which can be 70, 80, 90, or any value between 70-90 r / min; and the feeding rotating speed is 20-30 r / min.

[0100] After obtaining the surface layer material granules and the core layer material granules, the mixture is granulated to obtain the core layer material granules.

[0101] Specifically, the surface layer material granules and the core layer material granules are respectively added into a single-screw extruder and a conical twin-screw extruder, and then extruded at high temperature in a co-extrusion die to obtain a molded co-extrusion plastic composite material.

[0102] The heating cylinder temperature of the conical twin-screw extruder is 160-200℃, which can be 160, 170, 180, 190, 200, or any value between 160-200℃; the temperature of the confluence core is 150-165℃, which can be 150, 155, 160, 165, or any value between 150-165℃; the die temperature is 150-180℃, which can be 150, 160, 170, 180, or any value between 150-180℃; the rotating speed of the main machine is adjusted to 5-20 r / min, which can be 5, 10, 15, 20, or any value between 5-20 r / min; the rotating speed of the feeding speed knob is adjusted to 5-10 r / min, which can be 5, 6, 7, 8, 9, 10, or any value between 5-10 r / min; the pressure is 20-40 MPa, which can be 20, 30, 40, or any value between 20-40 MPa; and the current of the main machine is controlled to be 30A-45A, which can be 30, 35, 40, 45, or any value between 30A-45A.

[0103] Finally, the molded material is water-cooled and molded, and then cut to obtain the reed-based foamed wood-plastic co-extrusion wood-grain shell material.

[0104] The present application adopts high and low mesh reed fiber powder, increases material toughness, improves the use ratio of reed powder, reduces density and reduces material cost; meanwhile, the added nano calcium carbonate and surface modifier modify the surface of reed fiber, which plays the purpose of inorganic and organic activation modification, increases the interface compatibility with plastic, and the prepared raw material contains lignin sulfonate sodium similar to adhesive material, which can promote the interface compatibility of reed powder and unsaturated olefin resin.

[0105] In order to further understand the present application, the reed-based foamed wood-plastic co-extrusion wood-grain-like shell material and the preparation method thereof provided by the present application are described below in combination with examples, and the protection scope of the present application is not limited by the following examples.

[0106] In the following examples, the high-mesh reed powder particles are 60-100 mesh reed powder with a water content of less than or equal to 4%;

[0107] The low-mesh reed powder particles are 30-60 mesh reed powder with a water content of less than or equal to 4%.

[0108] Example 1

[0109] The reed-based foamed wood-plastic co-extrusion wood-grain-like shell material with excellent high-strength performance based on reed in the present example.

[0110] The surface layer material composition includes: 20 kg of high-mesh reed powder particles, 20 kg of high-density polyethylene, 10 kg of polypropylene, 5 kg of shell powder, 5 kg of lignin sulfonate sodium, 1 kg of nano calcium carbonate, 2 kg of lubricant EBS, 0.2 kg of gamma-aminopropyl triethoxysilane (KH-550), 0.4 kg of antioxidant (1010), 2 kg of anti-corrosion agent zinc borate, 2 kg of compatibility agent maleic anhydride grafted PE, 0.4 kg of composite anti-ultraviolet absorber (mass ratio of o-hydroxybenzoic acid phenyl ester: hexamethylphosphoric triamide is 1:1), and 3 kg of wood-grain-like color master batch.

[0111] The core layer material composition includes: 56 kg of low-mesh reed powder particles, 30 kg of high-density polyethylene, 3 kg of foaming agent 4,4-diazohydrazine diphenyl ether, 5 kg of glass fiber, 10 kg of shell powder, 10 kg of lignin sulfonate sodium, 2 kg of nano calcium carbonate, 2.5 kg of lubricant EBS, 0.1 kg of azodicarbonamide, 0.1 kg of stearic acid, and 2.5 kg of compatibility agent maleic anhydride grafted PE.

[0112] The production process of the present application is as shown in Figure 1 and includes the following steps:

[0113] 1) The raw materials A: high-density polyethylene, polypropylene, shell powder, lubricant EBS, antioxidant 1010, zinc borate, compatible agent maleic anhydride grafted PE, composite anti-ultraviolet absorber, wood grain color masterbatch are weighed according to the proportion in the surface layer material formula, put into the material cylinder A, and dried to obtain raw material A for standby.

[0114] 2) The high-mesh reed powder particles, sodium lignosulfonate, and nano calcium carbonate are weighed according to the proportion in the surface layer material formula, put into the second material cylinder, dried in the drying machine at 100℃ for 20 minutes, and then KH-550 is added and put into the material cylinder B. After mixing uniformly for 5 minutes, it is cooled for standby.

[0115] 3) A material is added to the high-speed mixer, and stirred at high speed; when the temperature of the high-speed mixer rises to 60℃, B material is added, stirred for 20 minutes, discharged, and cooled to 45℃.

[0116] 4) Granulation: the uniformly mixed raw materials are added to a parallel twin-screw extruder for mixing, granulation, and surface layer granulation material, and the temperature of the 75A parallel twin-screw extruder is set to 10 segments of heating cylinder temperature of 155℃, 160℃, 160℃, 170℃, 170℃, 170℃, 175℃, 175℃, 180℃, and 180℃, respectively, the main machine speed is 85 r / min, and the feeding speed is 30 r / min. The machine parameters are debugged to find the optimal parameters.

[0117] 5) High-density polyethylene, azodicarbonamide, shell powder, sodium lignosulfonate, nano calcium carbonate, foaming agent 4,4-dihydrazine diphenyl ether, lubricant EBS, and compatible agent maleic anhydride grafted PE are weighed according to the proportion in the core layer material formula, put into the third material cylinder, and dried to obtain raw material C. Low-mesh reed powder particles and glass fibers are weighed according to the proportion in the core layer material formula, put into the fourth material cylinder, dried, and then stearic acid is added to obtain raw material D.

[0118] 6) The third material raw material C is added to the high-speed mixer, stirred at high speed, and then the fourth material raw material D is added after warming up, stirred, and cooled to obtain a mixture. The mixture is granulated in a parallel twin-screw granulator to obtain core layer granulation material.

[0119] 7) Extrusion molding: after the surface layer granulation material and the core layer granulation material are extruded in a conical twin-screw extruder co-extrusion mold, a molded co-extrusion plastic material is obtained. After the extrusion temperature reaches the set temperature for 30 minutes, the material bin is filled by starting the feeding machine. The temperature of the 4 segments of the heating cylinder of the conical twin-screw extruder is 160℃, 170℃, 180℃, and 185℃, respectively, the combined core temperature is 165℃, the mold temperature is 170℃, the rotating main machine speed knob is 5 r / min, the rotating feeding speed knob is 6 r / min, the pressure is 25 MPa, and the main machine current is controlled at 40 A. The machine parameters are debugged to find the optimal parameters.

[0120] 8) Cooling, by means: water cooling circulation.

[0121] 9) Forming the product by directional cutting.

[0122] The reed-based foamed wood-plastic co-extrusion imitation wood grain shell material prepared in the embodiment 1 of the present application is subjected to scanning electron microscope analysis, and the electron microscope graph is shown in Figures 2-6 Figure 2 The scanning electron microscope graph of the core layer of the reed-based foamed wood-plastic co-extrusion imitation wood grain shell material prepared in the embodiment 1 of the present application; Figure 3 The scanning electron microscope graph of the core layer of the reed-based foamed wood-plastic co-extrusion imitation wood grain shell material prepared in the embodiment 1 of the present application; Figure 4 The scanning electron microscope graph of the core layer of the reed-based foamed wood-plastic co-extrusion imitation wood grain shell material prepared in the embodiment 1 of the present application; Figure 5 The scanning electron microscope graph of the surface layer of the reed-based foamed wood-plastic co-extrusion imitation wood grain shell material prepared in the embodiment 1 of the present application; Figure 6 The scanning electron microscope graph of the surface layer of the reed-based foamed wood-plastic co-extrusion imitation wood grain shell material prepared in the embodiment 1 of the present application; from Figures 2-6 It can be seen that the reed powder particles are compatible with the PE resin.

[0123] Embodiment 2

[0124] The reed-based foamed wood-plastic co-extrusion imitation wood grain shell material with high strength and excellent performance prepared in the embodiment.

[0125] The surface layer material composition includes: high-mesh reed powder particles 25 kg, low-density polyethylene 20 kg, polypropylene 10 kg, shell powder 5 kg, sodium lignosulfonate 5 kg, nano calcium carbonate 1 kg, lubricant EBS 2 kg, sodium dodecyl benzene sulfonate 0.2 kg, antioxidant (1010) 0.4 kg, preservative zinc borate 2 kg, compatibility agent maleic anhydride grafted PE 2 kg, composite anti-ultraviolet absorber (phenyl o-hydroxybenzoate: 2-hydroxy-4-n-octyloxy benzophenone: m-dihydroxybenzene monobenzoate = 1:1:1) 0.4 kg, imitation wood grain color master batch 3 kg.

[0126] The core layer material composition includes: low-mesh reed powder particles 50 kg, low-density polyethylene 30 kg, foaming agent azodicarbonamide 3 kg, glass fiber 5 kg, shell powder 10 kg, sodium lignosulfonate 10 kg, nano calcium carbonate 2 kg, lubricant EBS 2.5 kg, sodium dodecyl benzene sulfonate 0.1 kg, stearic acid 0.1 kg, compatibility agent maleic anhydride grafted PE 2.5 kg.

[0127] The production process of the present application is shown in Figure 1 and includes the following steps:

[0128] ​1) The raw materials A: low-density polyethylene, polypropylene, shell powder, lubricant EBS, antioxidant 1010, zinc borate, compatible agent maleic anhydride grafted PE, composite anti-ultraviolet absorber, wood grain color masterbatch are weighed according to the proportion in the surface layer material formula, put into the material cylinder A, and dried to obtain raw material A for standby.

[0129] 2) The high-mesh reed powder particles, sodium lignosulfonate, and nano calcium carbonate are weighed according to the proportion in the surface layer material formula, put into the second material cylinder, dried in the drying machine at 100°C for 20 min, and then sodium dodecyl benzene sulfonate is added into the material cylinder B. After mixing and stirring for 5 min, it is cooled for standby.

[0130] 3) The A material is added to the high-speed mixer, and stirred at high speed; when the temperature of the high-speed mixer rises to 70°C, the B material is added, stirred for 20 min, discharged, and cooled to 45°C.

[0131] 4) Granulation: the mixed raw materials are added to the parallel twin-screw extruder for mixing and granulation to obtain the surface layer granulated material. The temperature of the 75A parallel twin-screw extruder is set to 10 segments of heating cylinder temperature of 155°C, 160°C, 160°C, 170°C, 170°C, 170°C, 175°C, 175°C, 180°C, and 180°C, the main machine speed is 85 r / min, and the feeding speed is 30 r / min. The machine parameters are adjusted to find the optimal parameters.

[0132] 5) The low-density polyethylene, polypropylene, shell powder, foaming agent azodicarbonamide, lubricant EBS, and compatible agent maleic anhydride grafted PE are weighed according to the proportion in the core layer material formula, put into the third material cylinder, and dried to obtain raw material C. The reed powder particles, glass fiber, sodium lignosulfonate, and nano calcium carbonate are weighed according to the proportion in the core layer material formula, put into the fourth material cylinder, dried, and then sodium dodecyl benzene sulfonate and stearic acid are added to obtain raw material D.

[0133] 6) The third material raw material C is added to the high-speed mixer, and after the temperature is raised by high-speed stirring, the fourth material raw material D is added, stirred, and cooled to obtain a mixture. The mixture is granulated in a parallel twin-screw granulator to obtain a core layer granulated material.

[0134] 7) Extrusion molding: after the surface layer granulated material and the core layer granulated material are extruded in a conical twin-screw extruder co-extrusion mold, a molded co-extrusion plastic material is obtained. After the extrusion temperature reaches the set temperature for 30 min, the material bin is filled by starting the feeding machine. The temperature of the 4 segments of heating cylinder of the conical twin-screw extruder is 160°C, 170°C, 180°C, and 185°C, respectively, the combined core temperature is 165°C, the mold temperature is 170°C, the rotating main machine speed knob is 5 r / min, the rotating feeding speed knob is 6 r / min, the pressure is 25 MPa, and the main machine current is controlled at 40 A. The machine parameters are adjusted to find the optimal parameters.

[0135] 8) Cooling, mode: water cooling circulation.

[0136] 9) Forming the product by directional cutting.

[0137] Example 3

[0138] The reed-based high-strength foamed wood-plastic co-extrusion wood-grain shell material of the embodiment has excellent performance.

[0139] The surface layer material composition includes: 30 kg of high-mesh reed powder particles, 20 kg of high-density polyethylene, 10 kg of polypropylene, 5 kg of shell powder, 5 kg of sodium lignosulfonate, 1 kg of nano calcium carbonate, 2 kg of lubricant EBS, 0.2 kg of sodium dodecyl benzene sulfonate, 0.4 kg of antioxidant (1010), 2 kg of zinc borate, 2 kg of maleic anhydride grafted PE, 0.4 kg of composite ultraviolet absorption agent (phenyl salicylate: hexamethyl phosphorus triamide mass ratio is 1:1), and 3 kg of wood-grain color master batch.

[0140] The core layer material composition includes: 50 kg of low-mesh reed powder particles, 30 kg of high-density polyethylene, 3 kg of foaming agent azodicarbonamide, 5 kg of glass fiber, 10 kg of shell powder, 10 kg of sodium lignosulfonate, 2 kg of nano calcium carbonate, 2.5 kg of lubricant EBS, 0.1 kg of stearic acid, and 2.5 kg of maleic anhydride grafted PE.

[0141] The production process of the application is as shown in Figure 1 and includes the following steps:

[0142] 1) The raw materials A: high-density polyethylene, polypropylene, shell powder, lubricant EBS, antioxidant 1010, zinc borate, maleic anhydride grafted PE, composite ultraviolet absorption agent, and wood-grain color master batch are weighed according to the proportions in the surface layer material formula, put into the barrel A, dried to obtain the raw material A, and used as needed.

[0143] 2) The high-mesh reed powder particles, sodium lignosulfonate, and nano calcium carbonate are weighed according to the proportions in the surface layer material formula, put into the second barrel, dried in the drying machine at a temperature of 100 DEG C for 20 min, then the sodium dodecyl benzene sulfonate is added and put into the barrel B, mixed uniformly, stirred for 5 min, and cooled for standby.

[0144] 3) The A material is added to the high-speed mixer and stirred at high speed; when the temperature of the high-speed mixer rises to 70 DEG C, the B material is added, stirred for 20 min, discharged, and cooled to 45 DEG C.

[0145] 4) granulation, the mixed raw materials are added into a parallel twin screw extruder for mixing, granulation to obtain a surface layer granulated material, the temperature of the 75A parallel twin screw extruder is set to be 155℃, 160℃, 160℃, 170℃, 170℃, 170℃, 175℃, 175℃, 180℃, 180℃ in sequence, the main machine speed is 85 r / min, the feeding speed is 30 r / min, the machine parameters are debugged to find the optimal parameters.

[0146] 5) high-density polyethylene, polypropylene, shell powder, foaming agent, lubricant EBS, and compatible agent maleic anhydride grafted PE are weighed according to the proportion of the core layer material formula, put into the third barrel, and dried to obtain raw material C; low-mesh reed powder particles, glass fiber, and sodium lignosulfonate are weighed according to the proportion of the core layer material formula, put into the fourth barrel, dried, and then stearic acid is added to obtain raw material D;

[0147] 6) the third material raw material C is added in a high-speed mixer, the fourth material raw material D is added after high-speed stirring and heating, stirring and cooling to obtain a mixture, and the mixture is granulated in a parallel twin screw granulator to obtain a core layer granulated material;

[0148] 7) extrusion molding, the surface layer granulated material and the core layer granulated material are extruded in a conical twin screw extruder to obtain a molded co-extrusion plastic material; after the extrusion temperature reaches the set temperature for 30 min, the material bin is filled by starting the feeding machine. The temperature of the 4th heating barrel of the conical twin screw extruder is 160℃, 170℃, 180℃, 185℃ in sequence, the confluence core temperature is 165℃, the mold temperature is 170℃, the rotating main machine speed knob is 5 r / min, the rotating feeding speed knob is 6 r / min; the pressure is 25 MPa, and the main machine current is controlled at 40 A. The machine parameters are debugged to find the optimal parameters.

[0149] 8) cooling, using a water cooling cycle.

[0150] 9) through directional cutting molding, a product is obtained.

[0151] Comparative Example 1

[0152] On the basis of Example 1, the shell powder in the core layer is replaced by heavy calcium carbonate powder, and other conditions remain unchanged to obtain a product.

[0153] Comparative Example 2

[0154] On the basis of Example 1, the sodium lignosulfonate in the surface layer and the core layer is omitted, and other conditions remain unchanged to obtain a product.

[0155] Comparative Example 3

[0156] On the basis of Example 1, the surface modifier in the surface layer is omitted, and other conditions remain unchanged to obtain a product.

[0157] Referring to Figure 7 , Figure 7 The infrared spectrum of the reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material surface layer material prepared in Example 1 and Comparative Example 3 is shown in the figure.

[0158] Test Example 1

[0159] The mechanical properties of the prepared reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material were tested, and the results are shown in Table 1. Table 1 shows the mechanical property test results of the reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material prepared in Examples 1-3 and Comparative Examples 1-3.

[0160] 1. Test method of static bending strength

[0161] According to ASTM D790-17, a three-point bending mode was used on a DDL20 million capacity mechanical tester with a span of 64 mm and a loading rate of 2 mm / min.

[0162] 2. Test method of bending elastic modulus

[0163] According to ASTM D790-17, a three-point bending mode was used on a DDL20 million capacity mechanical tester with a span of 64 mm and a loading rate of 2 mm / min.

[0164] Table 1 Mechanical property test results of reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell material

[0165]

[0166] The test results show that the reed nanocrystal plastic composite material prepared in the application has a significant improvement in static bending strength and bending elastic modulus compared to Examples 1-3 and Comparative Examples 1-3. The product quality far exceeds the national standard for building decoration plastic-wood composite wallboard QB / T 2630-2010 for determining static bending strength (static bending strength ≥ 24 MPa) and bending elastic modulus (≥ 2300 MPa) performance indicators.

[0167] Comparative Example 1 uses heavy calcium carbonate instead of shell powder (CaCO3≥95%), so the shell powder is rich in active calcium carbonate, and the shell powder can produce spherical pores in the plastic composite material, which can blunt the crack tip and effectively prevent the propagation of cracks, thereby significantly improving the impact resistance and ductility of the material. Heavy calcium carbonate does not contain active calcium carbonate, resulting in a decrease in static bending strength and bending elastic modulus;

[0168] Comparative Example 2 Due to the removal of sodium lignosulfonate, sodium lignosulfonate is rich in carbon skeleton, sulfonic acid group and methoxy group, and has a large number of phenolic / alcoholic hydroxyl groups, which plays a dual role of "rigid particle + interface coupling". The introduction of sodium lignosulfonate into the high-density polyethylene (HDPE) matrix improves the static bending strength and bending elastic modulus of the material. Conversely, the lack of flexible fiber network leads to a decrease in static bending strength and bending elastic modulus.

[0169] Comparative Example 3 does not add a surface modifier. The surface modifier can react with the surface of the plant fiber to form a hydroxyl group, graft a hydrophobic group to reduce the moisture absorption rate, and form a covalent bridge with the resin to improve the interfacial adhesion and simultaneously improve the strength and modulus performance of the composite. The lack of a surface modifier in Comparative Example 3 leads to a decrease in static bending strength and bending elastic modulus.

[0170] Test Example 2

[0171] The prepared reed-based foamed wood-plastic co-extrusion wood grain shell material was tested for density, formaldehyde emission and moisture absorption performance according to the method of GB / T 17657-2022. The test results are shown in Table 2.

[0172] Table 2 Formaldehyde emission and moisture absorption performance test results of reed-based foamed wood-plastic co-extrusion wood grain shell material

[0173]

[0174] The test results show that the water absorption expansion rate of the reed-based foamed wood-plastic co-extrusion wood grain shell material of Examples 1-3 is significantly lower than that of Comparative Examples 1-3. The formaldehyde emission meets the international E0 (E0≤0.5mg / L) standard, has environmental protection performance, and greatly improves the working environment of workers.

[0175] In terms of material density, the shell powder is in the form of porous lamellar, and the volume of the shell powder is larger than that of the same weight of heavy calcium, so the overall apparent density decreases. When the shell powder is replaced by heavy calcium, the melt strength of the wallboard decreases and the density of the product increases. In terms of formaldehyde emission, the wood-plastic system itself has very little glue, and the formaldehyde is mainly derived from additives or interfacial coupling agents. The shell powder contains chitin, amino acids and other alkaline components, which can adsorb and decompose free formaldehyde into CO2 and water. The replacement of shell powder with heavy calcium does not have the effect of adsorbing and decomposing free formaldehyde, resulting in an increase in formaldehyde emission. In terms of water absorption thickness expansion rate, the lamellar shell powder is oriented parallel during the extrusion process, forming a physical barrier layer; at the same time, its surface hydrophobicity is stronger than that of heavy calcium, which can significantly reduce the water molecule penetration rate. The replacement of shell powder with heavy calcium does not form a physical barrier layer; at the same time, its surface hydrophobicity is weaker than that of shell powder, resulting in an increase in water absorption thickness expansion rate.

[0176] Comparative Example 2 Due to the removal of sodium lignosulfonate, the density of sodium lignosulfonate itself (≈1.3 g / cm 3 ) is lower than that of common inorganic fillers, and its sheet structure can occupy a larger volume under the same mass, so the overall apparent density increases. Sodium lignosulfonate has sulfonic acid groups, hydroxyl groups, and a small amount of amino groups, which can undergo condensation / Mannich reaction with free formaldehyde, "locking" formaldehyde into a three-dimensional network structure; at the same time, its alkalinity can also neutralize the acidic formaldehyde released by the adhesive. The loss of sodium lignosulfonate results in an increase in formaldehyde release. Lignin itself is hydrophobic and rigid and sheet-like, which can form a "tile-like" barrier at the wood / plastic interface; at the same time, its anionic surface can adsorb part of the polar water molecules, reducing the osmotic pressure. The loss of sodium lignosulfonate results in an increase in the 24h water absorption thickness expansion rate.

[0177] Comparative Example 3 Due to the absence of a surface modifier, its own amount is low, and has little effect on the overall density, which is basically unchanged. The amount of glue in the wood-plastic composite is very small, and formaldehyde is mainly derived from a small amount of coupling agent or additive. After the interface reaction of silane coupling agent, the residual formaldehyde can be bonded to the polymer chain, and the loss of surface modifier results in an increase in formaldehyde release. In terms of water absorption thickness expansion rate, the main component of the surface modifier is silane coupling agent, which forms a hydrophobic "bridge" at the reed powder / plastic interface, making it difficult for water molecules to penetrate. The loss of surface modifier results in an increase in water absorption thickness expansion rate.

[0178] Test Example 3

[0179] The prepared reed-based foamed wood-plastic co-extrusion imitation wood grain shell material was tested for flame retardant performance, and the test results are shown in Table 2.

[0180] 1. Oxygen index test method

[0181] The sample was vertically clamped in a transparent combustion cylinder, and adjustable oxygen / nitrogen mixed gas was introduced. The top end was ignited, and the oxygen concentration was gradually reduced until the flame could not burn for ≥3 min. The oxygen volume fraction was recorded as the oxygen index. GB / T 2406.2 or ISO4589-2 was performed, and the average value of 5 samples was taken as the result for determining the flame retardant grade of the material.

[0182] 2. Test method for average burning time and average burning height

[0183] According to GB / T 2408 vertical burning method: the sample was 125 mm x 13 mm vertically fixed, and a 50 W Bunsen burner flame was applied for 10 s. The flame self-extinguishing time (burning time) and char spreading height (burning height) were recorded, and the average of 5 samples was taken.

[0184] 3. Smoke density rating SDR

[0185] In the GB / T 8627 smoke density box, the sample was horizontally placed under a 25 kW·m-2 Radiant or small flame ignition, measurement of light attenuation of the light beam passing through the smoke, automatic recording of the maximum smoke density value (MSD) and smoke density rating (SDR0-SDR 100 ), for additional classification of wall / floor covering materials for their burning behavior.

[0186] Table 3 Flame-retardant performance test results of reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell materials

[0187]

[0188] The test results show that the reed-based foamed wood-plastic co-extrusion wood-grain-imitating shell materials prepared in Examples 1-3 have good flame-retardant performance.

[0189] Comparative Example 1 uses heavy calcium carbonate instead of shell powder, and the quality of the carbon layer is reduced due to the difference in morphology. The shell powder is in the form of porous lamella, and after heating, it can form a continuous and dense CaCO3+CaO solid "tile" carbon layer on the surface of the resin, which can isolate oxygen and heat. The heavy calcium carbonate is in the form of solid cubic / spindle particles, and cannot form a film. When the resin is pyrolyzed, the carbon layer is loose and easy to fall off, and the heat and oxygen isolation effect is poor, which leads to a decrease in LOI, and the flame is more likely to spread upward, which increases the burning height. The difference in decomposition temperature between Comparative Example 1 and the examples is mainly due to the early weight loss and gas release of the shell powder. Due to crystal defects and organic residues, the decomposition temperature of CaCO3 is 30-40℃ lower than that of heavy calcium carbonate; CO2 is released earlier, and the combustible hydrocarbons produced by the thermal decomposition of the resin play a role in gas dilution. The decomposition of heavy calcium carbonate lags behind, and the release rhythm of CO2 is different from the peak weight loss of the resin, and the dilution effect is weak, the average burning time is shortened due to the high temperature of the combustion front, and the smoke particles are more fully volatilized (the SDR is increased). The difference in smoke nucleation leads to an increase in smoke density. The shell powder lamella can absorb / intercept part of the aromatic hydrocarbon fragments, reducing the smoke nuclei; the surface of the heavy calcium carbonate particles is smooth and has almost no adsorption capacity, and the thermal conductivity is high, which makes the polymer cracking more complete, releases more aromatic volatile substances, and increases the smoke density rating. Replacing the shell powder with heavy calcium carbonate leads to a decrease in the oxygen index, an acceleration of the burning, a higher flame, and denser smoke.

[0190] In Comparative Example 2, omitting sodium lignosulfonate resulted in the disappearance of the char skeleton, leading to a thinner char layer and more cracks. When heated, sodium lignosulfonate first melts and then condenses, forming an "aromatic-glassy" continuous char layer with the cellulose in the wood flour. Removing sodium lignosulfonate resulted in only the wood flour itself carbonizing, leading to a loose, easily cracked char layer, a decreased oxygen index, and a rapid upward flame along the cracks, resulting in an increase in combustion height of 154 mm. When sodium lignosulfonate decomposes, it releases sulfur-containing free radicals such as SO2 and thiophenol, which can capture ·H and ·OH, inhibiting gas-phase chain reactions. Removing it increased the concentration of combustible gases, slightly prolonging the combustion time (faster but more sustained flame spread), but drastically increasing the amount of flue gas generated, with the SDR soaring to 86. Furthermore, the sodium lignosulfonate char layer can adsorb aromatic hydrocarbon fragments while releasing non-combustible gases (CO2, SO2) to dilute the oxygen concentration. Without sodium lignosulfonate, all volatiles enter the smoke core, resulting in more complete combustion and an approximately 48% increase in smoke density.

[0191] In Comparative Example 3, omitting the surface modifier resulted in a weak boundary at the reed powder / plastic interface. Upon heating, the reed powder prematurely peeled off, failing to form a continuous, dense char layer. The resin was directly exposed, leading to a decrease in the oxygen index and a rapid flame rise along the exposed path, resulting in an 89mm increase in combustion height. Furthermore, the interfacial voids provided channels for volatiles, making it easier for thermally decomposed aromatic hydrocarbons and aldehydes to enter the gas phase, resulting in incomplete combustion, an approximately 55% increase in soot particle nucleation rate, and a surge in the SDR to 81. Due to the discontinuous char layer, heat return was slow, surface temperature rise was delayed, and the combustion front advancement speed actually decreased, extending the average combustion time by about 1 second.

[0192] The aforementioned formulation is characterized by a matrix of modified reed fiber powder and shell powder, which exhibit superior toughness. The addition of shell powder creates spherical pores in the composite material. These pores blunt crack tips and effectively prevent crack propagation, significantly improving the material's impact resistance and ductility, while greatly reducing the product's density and enhancing its mechanical and flame-retardant properties. Simultaneously, sodium lignosulfonate, a polar binder present in the reed powder, is added to improve the interfacial compatibility between the reed powder and the matrix and fillers, thereby increasing the wood-plastic composite's strength. The surface modifier reacts with plant fiber surfaces to form hydroxyl groups, grafting hydrophobic groups and reducing moisture absorption; at the other end, it forms a covalent bridge with the resin, improving interfacial adhesion. This results in a simultaneous increase in the composite material's strength and modulus, as well as its flame-retardant properties.

[0193] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A reed-based foamed wood plastic co-extruded wood grain imitation shell material, characterized in that, The raw materials for preparing the surface layer include: two different mesh reed powder particles, unsaturated olefin resin, nano calcium carbonate, surface modifier, sodium lignosulfonate, glass fiber, shell powder and additives; the surface modifier is selected from at least one of stearic acid, silane coupling agent, titanate coupling agent, sodium dodecyl benzene sulfonate.

2. The reed-based, foamed, wood-plastic, co-extruded, wood-grain shell material of claim 1, wherein, The additives are selected from at least one of foaming agent, lubricant, antioxidant, preservative, compatibilizer, composite anti-ultraviolet absorbing agent and wood grain color master batch.

3. The reed-based, foamed, wood-plastic, co-extruded, wood-grain shell material of claim 1, wherein, The surface layer is prepared from the following raw materials in parts by mass: high mesh reed powder particles 20-30 parts, unsaturated olefin resin 25-35 parts, shell powder 3-5 parts, sodium lignosulfonate 5-10 parts, nano calcium carbonate 1-2 parts, lubricant 2-2.5 parts, surface modifier 0.1-0.2 parts, antioxidant 0.2-0.4 parts, preservative 2-5 parts, compatibilizer 2-2.5 parts, composite anti-ultraviolet absorbing agent 0.2-0.4 parts, wood grain color master batch 2-3 parts. The high mesh reed powder particles are 60-100 mesh reed powder with water content less than or equal to 4%. The raw materials for preparing the core layer include: low mesh reed powder particles 50-70 parts, unsaturated olefin resin 25-35 parts, foaming agent 2-3 parts, glass fiber 5-10 parts, shell powder 5-10 parts, sodium lignosulfonate 5-10 parts, nano calcium carbonate 1-2 parts, lubricant 2-2.5 parts, surface modifier 0.1-0.2 parts, compatibilizer 2-2.5 parts. The low mesh reed powder particles are 30-60 mesh reed powder with water content less than or equal to 4%. The unsaturated olefin resin is selected from at least two of high density polyethylene resin, low density polyethylene resin and polypropylene resin.

4. The reed-based, foamed, wood-plastic, co-extruded, wood-grain shell material of claim 3, wherein, The melt index of the unsaturated olefin resin is 0.5-2.0 g / min. The composite anti-ultraviolet absorbing agent is selected from two or more of phenyl o-hydroxybenzoate, 2-hydroxy-4-n-octyloxybenzophenone, m-dihydroxybenzene monobenzoate, tris(1,2,2,6,6-pentamethylpiperidyl) phosphite, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine and hexamethylphosphorus triamide.

5. The reed-based, foamed, wood-plastic, co-extruded, wood-grain shell material of claim 3, wherein, The foaming agent is one of azodicarbonamide and 4,4-oxybis(hydrazine) diphenyl ether.

6. The reed-based, foamed, wood-plastic, co-extruded, wood-grain shell material of claim 3, wherein, The antioxidant is antioxidant 1010. The lubricant is EBS. The compatibilizer is maleic anhydride grafted PE. The preservative is zinc borate. The shell powder mesh is 200-800 mesh. The nano calcium carbonate has a particle size of 20-100 nm. The glass fiber has a length of 3-6 mm. The method comprises the following steps:

7. A process for the preparation of a bulrush-based foamed wood-plastic co-extruded wood-grain-imitating shell material according to any one of claims 1 to 6, characterized in that, a) preparing surface layer material granules: a1) mixing unsaturated olefin resin, shell powder, lubricant, antioxidant, compatibilizer, preservative, composite anti-ultraviolet absorbing agent and wood grain color master batch according to the proportions of the surface layer material formula, drying to obtain raw material A; mixing high mesh reed powder particles, sodium lignosulfonate and nano calcium carbonate according to the proportions of the surface layer material formula, drying and then adding surface modifier to obtain raw material B; ​ a2) mixing and stirring the raw material A, adding and mixing the raw material B after warming, cooling to obtain a mixture; a3) granulating the mixture to obtain the surface layer material granules; b) preparing the core layer material granules b1) weighing and mixing unsaturated olefin resin, foaming agent, shell powder, lubricant and compatibilizer according to the core layer material formula proportion, drying to obtain raw material C; weighing and mixing low mesh reed powder particles, glass fiber, sodium lignosulfonate and nano calcium carbonate according to the core layer material formula proportion, drying and then adding surface modifier to obtain raw material D; b2) mixing and stirring the raw material C, adding and mixing the raw material D after warming, cooling to obtain a mixture; b3) granulating the mixture to obtain the core layer material granules; c) extruding the surface layer material granules and the core layer material granules respectively to obtain the co-extruded composite material; d) cooling and cutting the co-extruded composite material to obtain the reed-based foamed wood-plastic co-extruded wood grain shell material.

8. The preparation method according to claim 7, characterized in that, In step a2), the mixing and stirring speed is 25-35 r / min, the time is 15-20 min, and the temperature is 50-80℃. In step a3), the granulation parameters are: parallel double screw extruder temperature is 150-180℃, main machine speed is 70-90 r / min, and feeding speed is 20-30 r / min.

9. The preparation method according to claim 7, characterized in that, In step b2), the mixing and stirring speed is 25-35 r / min, the time is 15-20 min, and the temperature is 50-80℃. In step b3), the granulation parameters are: parallel double screw extruder temperature is 150-180℃, main machine speed is 70-90 r / min, and feeding speed is 20-30 r / min.

10. The preparation method according to claim 7, characterized in that, Step c) includes the following steps: adding the surface layer material granules and the core layer material granules into single screw extruder and conical twin screw extruder respectively, and then extruding and molding in the co-extrusion die to obtain the molded co-extruded composite material; The heating cylinder temperature of the conical twin screw extruder is 160-200℃, the combined core temperature is 150-165℃, the die temperature is 150-180℃, the main machine speed is adjusted to 5-20 r / min, the feeding speed is adjusted to 5-10 r / min, the pressure is 20-40 MPa, and the main machine current is controlled at 30A-45A.

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