Environment-friendly nano antibacterial PE (polyethylene) wood-plastic plate

Abstract

The invention discloses an environment-friendly nano antibacterial PE (polyethylene) wood-plastic plate, which is prepared from wood flour, silane modified PE gel, glass fiber powder, nano cellulose, borax, acrylate resin and PE wax. According to the invention, through chemical bond connection between the silane modified PE gel and inorganic particles such as the glass fiber powder and the nano cellulose, and a toughening effect of the acrylate resin, mechanical properties such as tensile strength, bending strength and impact strength of the plate are greatly improved; through use of high-crystallinity nano-crystalline cellulose and modified wood flour, the hydrophobicity of the material is improved, meanwhile, due to the fracture and repair mechanism of boric acid ester bonds, the network structure is compact, water is difficult to permeate into a cross-linked network of PE / wood flour, and thus the water resistance of the board is improved; phosphonic acid and quaternary phosphonium salt ionic liquid in the silane modified PE gel have lasting antibacterial property; and the balance of water permeability and waterproofness is realized through a process of combining cross-linked gel, evaporation hole making and hot press molding.

Description

Technical Field

[0001] The present invention relates to the technical field of modified wood-plastic boards, and particularly to an environmentally friendly nano-bacteriostatic PE wood-plastic board. Background Art

[0002] Wood-plastic composites are a new type of environmentally friendly material, which are formed by hot extrusion after mixing plastic and wood fibers in a certain proportion. They have good processability, strength, water resistance and corrosion resistance, and are widely used in industries such as construction and furniture. Among them, wood-plastic floors made from recycled PP, PE or PVC as raw materials are the most widely used.

[0003] However, the modification of existing PE wood-plastic floors is often limited to physical blending. For example, hydrophobic modified wood powder is blended with PE, and even to enhance the uniformity of the wood powder and PE phases, thermopolymerizable monomers (such as methyl methacrylate MMA, butyl methacrylate BMA, styrene St, etc.) are evenly sprayed on the wood powder and cross-linked with PE through heat treatment; another example is to blend maleic anhydride grafted polyethylene (MAPE) to improve the mixing uniformity of wood powder and PE, etc. Most of them resort to physical modification, so that the disadvantages of PE or wood powder itself, such as poor impact resistance, poor rigidity, and poor high-temperature resistance, still exist in the PE-based wood-plastic composite materials.

[0004] In addition, traditional wood-plastic materials have problems such as high water absorption and insufficient antibacterial performance, which limit their application in humid environments. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies in the prior art and propose an environmentally friendly nano-bacteriostatic PE wood-plastic board.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] An environmentally friendly nano-bacteriostatic PE wood-plastic board, comprising the following components in parts by weight:

[0008] 100 parts of wood powder;

[0009] 30 - 50 parts of silane-modified PE gel: a xylene-swollen gel of silane-modified PE;

[0010] 15 - 20 parts of glass fiber powder (ground powder of waste wind power generation blades);

[0011] 7 - 9 parts of nano-cellulose;

[0012] 2 - 4 parts of borax;

[0013] 1.5 - 2.5 parts of acrylate resin;

[0014] 3 - 5 parts of PE wax;

[0015] The preparation process of the silane-modified PE gel is as follows:

[0016] Mix PE particles and xylene, swell at 80 °C for 15 min, sequentially add vinyl silane, vinyl phosphonic acid, 4-vinylbenzyltributylphosphonium chloride, and organic peroxide, and react at 80 °C for 3 - 4 h to obtain the silane-modified PE gel;

[0017] Preferably, in the preparation process of the silane-modified PE gel, the weight ratio of PE particles, xylene, vinyl silane, vinyl phosphonic acid, 4-vinylbenzyltributylphosphonium chloride, and organic peroxide is 100:115 - 120:2 - 4:3 - 5:3 - 5:0.1 - 0.2. By free radical initiation, the double bond is grafted onto PE to produce modified PE with silane, phosphonic acid, and quaternary phosphonium salt ionic liquid groups. Silane can load inorganic particles or hydrolyze and crosslink to produce hydrogel. Phosphonic acid has the properties of crosslinking with borax and antibacterial performance. The quaternary phosphonium salt ionic liquid group has the properties of promoting dissolution, increasing solubility, and antibacterial performance.

[0018] Preferably, the vinyl silane is any one of vinyltriethoxysilane (VTES), vinyltris(2-methoxyethoxy)silane (VTMES), and 3-methacryloxypropyltrimethoxysilane (VMMS). Vinyltrimethoxysilane (VTMS) with too fast hydrolysis rate should be avoided to prevent excessive hydrolysis.

[0019] Preferably, the organic peroxide includes any one of dibenzoyl peroxide (BPO), triethylenetrione peroxide (TMA), and methylvinylformamide peroxide (MAPO).

[0020] Preferably, the production process of the glass fiber powder is as follows:

[0021] Crush waste wind turbine blades and then grind them into glass fiber powder with a particle size of 100 - 150 mesh; it can resist wind and sand, enhance waterproof performance, and extend the service life of wooden houses;

[0022] Preferably, the preparation of the nanocellulose:

[0023] Mix bleached kraft eucalyptus pulp with an H2S04 aqueous solution with a mass fraction of 58 - 62%, the dosage of the H2S04 aqueous solution is 8 ml / g of pulp, the reaction temperature is 50 - 60 °C, and the reaction time is 30 - 60 min to obtain acid pulp. After centrifugal separation, the centrifugate obtained by filtration is reserved for later use, and the obtained residue is dried to obtain nanocellulose; the nanocellulose with high crystallinity is used to enhance strength and at the same time improve the hydrophobicity of the material.

[0024] The present invention also provides a preparation method for the aforementioned environmentally friendly nano-bacteriostatic PE wood-plastic board, including the following steps:

[0025] S1. Preparation of Blended PE Particles:

[0026] Put the silane - modified PE gel, glass fiber powder and nanocellulose into a screw extruder to extrude and obtain blended PE particles; through silane mounting, the glass fiber powder, nanocellulose and silane - modified PE gel are connected by chemical bonds.

[0027] S2. Acid Treatment of Wood Flour:

[0028] Mix the wood flour and an aqueous H2S04 solution with a mass fraction of 58 - 62% (which can be replaced by the centrifuged liquid in the preparation process of nanocellulose) according to a weight ratio of 1:2 - 3, soak for 12 h, and stir to obtain acidic wood pulp; through acid modification, the wood flour can be made fluffy, thus further promoting the mixing of the wood flour and the PE phase.

[0029] S3. Hydrolysis Cross - Linking:

[0030] Put the blended PE particles, borax, acrylate resin and PE wax into the acidic wood pulp, raise the temperature, and react under closed conditions (equipped with a transparent observation port), at 90 - 120 °C, with stirring at 500 r / min for 0.5 - 1 h. After heating, the solution gradually becomes viscous and presents a homogeneous colloidal suspension (apparently without obvious particle sense) to obtain an injection - molding liquid; utilize the acidic condition to promote the hydrolysis cross - linking of silane without carrying inorganic substances, and the thermal cross - linking of borax with phosphonic acid, the surface hydroxyl and carboxyl groups of wood flour, etc., to form cross - linked components of each phase through chemical bonds. Therefore, from the appearance, there are no obvious aggregated particles.

[0031] S4. Evaporation for Pore Formation:

[0032] Immediately inject the newly prepared injection - molding liquid into a flat groove, heat and evaporate water at 150 °C to obtain a porous plate; the moisture content < 1%, and the porosity is 55.4%.

[0033] S5. Hot Pressing and Molding:

[0034] Use a hot press plate at 0.2 - 0.3 MPa and 125 - 135 °C to hot - press the porous plate in the flat groove, keep it warm at 125 - 135 °C for 30 min, trim the edges and grind the edges to obtain the finished PE - wood plastic board. In the state of anhydrous and softened PE, under the support of inorganic support agents (glass fiber powder, nanocellulose and wood flour), utilize the breakage and repair of borate bonds to realize the recombination of the cross - linked structure, and form a slightly dense and pressure - resistant water - permeable PE - wood plastic board finished product with a porosity of 25 - 30%.

[0035] It can also be continuously pressed and formed by a hot - press roller in an incubator.

[0036] Preferably, the temperature parameters of the five zones of the screw extruder in S1 are: 140 - 160 °C, 160 - 180 °C, 180 - 200 °C, 170 - 190 °C, and 180 - 200 °C, the nozzle temperature is 180 - 200 °C, and air needs to be released during the process to remove xylene.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. Through the chemical bond connection between the silane-modified PE gel and inorganic particles such as glass fiber powder and nanocellulose, and the toughening effect of the acrylate resin, the mechanical properties of the board such as tensile strength, bending strength, and impact strength are significantly improved.

[0039] 2. By using highly crystalline nanocellulose and modified wood powder, the hydrophobicity of the material is improved. At the same time, the fracture and repair mechanism of the borate ester bond makes the network structure relatively dense, and water is difficult to penetrate into the cross-linked network of PE / wood powder, thereby improving the water resistance of the board.

[0040] 3. The phosphonic acid in the silane-modified PE gel of the present invention has antibacterial properties, and the quaternary phosphonium salt ionic liquid group also has antibacterial properties. At the same time, borax can also play an antibacterial role under specific conditions. The synergistic effect of multiple antibacterial components enables the inhibition rates of the board against Escherichia coli and Staphylococcus aureus to reach more than 95% respectively; and the antibacterial components are evenly distributed in the board and will not significantly reduce the antibacterial effect due to the use time, ensuring long-term antibacterial performance.

[0041] 4. Through the process combining cross-linked gel - evaporation pore formation - hot pressing molding, the board has a certain porosity, and the water permeability is not less than 0.5 cm / s, meeting the requirements of water permeability; and after being saturated with water, through the sunshine dehydration test, the time required for the moisture content ≤ 1% is generally 1.5 - 2 min, indicating that its dehydration speed is fast, the main components are hydrophobic, and due to the self-repair of the borate ester bond when encountering water, the network structure is relatively dense, and water is difficult to penetrate into the interior of the board, achieving the balance of water permeability and waterproofness.

[0042] 5. In addition, the present invention also uses the ground powder of waste wind turbine blades as glass fiber powder, realizing the reuse of waste and reducing environmental pollution. Specific Embodiments

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the existing well-known technologies. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0044] I. Preparation of silane-modified PE gel:

[0045] Mix PE particles (PE recycled material, first grade, Binzhou Huayuan Plastic Technology Co., Ltd.) with xylene, swell at 80 °C for 15 min, and sequentially add vinyl silane, vinyl phosphonic acid (VPA, purity > 99%, Hubei Hongxin Ruiyu Fine Chemical Co., Ltd.), 4-vinylbenzyltributylphosphonium chloride [(VBP-Bu ionic liquid, in white powder form, melts into ionic liquid form at 60 °C), purity > 99%, Shanghai Aladdin Biochemical Technology Co., Ltd.] and organic peroxide, and react at 80 °C for 3 - 4 h to obtain silane-modified PE gel;

[0046] Among them, the weight ratio of PE particles, xylene, vinyl silane, vinyl phosphonic acid, 4-vinylbenzyltributylphosphonium chloride and organic peroxide is 100:115 - 120:2 - 4:3 - 5:3 - 5:0.1 - 0.2. Through free radical initiation, double bonds are grafted onto PE to produce modified PE with silane, phosphonic acid and quaternary phosphonium salt ionic liquid groups. Silane can load inorganic particles or hydrolyze and crosslink to produce hydrogel. Phosphonic acid has the properties of crosslinking with borax and antibacterial, and the quaternary phosphonium salt ionic liquid group has the properties of promoting dissolution, increasing compatibility and antibacterial.

[0047] Among them, the vinyl silane is any one of vinyltriethoxysilane (VTES), vinyltris(2-methoxyethoxy)silane (VTMES) and 3-methacryloxypropyltrimethoxysilane (VMMS). It is necessary to avoid using vinyltrimethoxysilane (VTMS) with too fast hydrolysis rate to avoid excessive hydrolysis.

[0048] Among them, the organic peroxide includes any one of diisopropyl peroxide (BPO), triethylenemethanetrione peroxide (TMA) and methylvinylformamide peroxide (MAPO).

[0049] The specific preparation examples are shown in Table 1 below:

[0050] Table 1. Formulation of silane-modified PE gel

[0051]

[0052] Comparing Comparative Preparation Examples 1 - 2 with Preparation Example 2, the gel of the products all decreases, indicating that the effect of the dosage of swollen xylene on the grafting rate first increases and then decreases.

[0053] Comparing Comparative Preparation Examples 3 - 4 with Preparation Example 2 shows that the grafting rate increases with the increase of the dosage of vinyl silane. However, excessive silane grafting may cause uncontrollable gel crosslinking of the PP main chain. During the preparation process of Comparative Preparation Example 4, there is particle agglomeration, which is instead not conducive to the uniform distribution of the later crosslinking network.

[0054] Comparing Preparation Examples 5-6 with Preparation Example 2, the absence of vinylphosphonic acid or VBP-Bu ionic liquid respectively reduces the crosslinking grafting rate, and it can be expected to have an adverse effect on the antibacterial performance and subsequent crosslinking.

[0055] Comparing Preparation Examples 7-8 with Preparation Example 2, the grafting rate increases with the increase in the amount of BPO. However, when it increases to a certain extent, the increase in the grafting rate is significantly smaller. Moreover, too much BPO will also cause the degradation of PP, and the PP in Preparation Example 8 has an obvious thinning phenomenon.

[0056] II. Recycling of glass fiber powder:

[0057] The production process of glass fiber powder is as follows:

[0058] The waste wind power generation blades are crushed and then ground into glass fiber powder with a particle size of 100-150 mesh; it can resist wind and sand, enhance the waterproof performance, and extend the service life of wooden houses.

[0059] III. Preparation of nanocellulose:

[0060] The bleached kraft eucalyptus pulp (“Longtou” brand bleached kraft eucalyptus pulp, APP Group) is mixed with an aqueous H2S04 solution with a mass fraction of 58-62%. The dosage of the aqueous H2S04 solution is 8 ml / g of pulp. The reaction temperature is 50-60 °C, and the reaction time is 30-60 min to obtain acid pulp. After centrifugal separation, the centrifugate obtained by filtration is reserved for later use, and the obtained residue is dried to obtain nanocellulose; the nanocellulose with high crystallinity is used to enhance the strength and at the same time improve the hydrophobicity of the material.

[0061] IV. Preparation of environmentally friendly nano antibacterial PE wood-plastic board:

[0062] S1. Preparation of blended PE particles:

[0063] The silane-modified PE gel, glass fiber powder, and nanocellulose are put into a screw extruder. The temperature parameters of the five zones of the screw extruder are: 140-160 °C, 160-180 °C, 180-200 °C, 170-190 °C, and 180-200 °C. The nozzle temperature is 180-200 °C. During the process, it is necessary to vent to remove xylene; the blended PE particles are obtained by extrusion; through silane grafting, the glass fiber powder, nanocellulose, and silane-modified PE gel are connected by chemical bonds.

[0064] S2. Acid treatment of wood powder:

[0065] The wood powder and an aqueous H2S04 solution with a mass fraction of 58-62% (which can be replaced by the centrifugate in the preparation process of nanocellulose) are mixed at a weight ratio of 1:2-3 and soaked for 12 h, and then stirred to obtain acid pulp; through acid modification, the wood powder can be made fluffy, thereby further promoting the mixing of the wood powder and the PE phase.

[0066] S3. Hydrolysis Crosslinking:

[0067] Put the blended PE particles, borax, acrylate resin, and PE wax into acid wood pulp, heat up, and react under sealed conditions (equipped with a transparent observation port), at 90 - 120 °C, and stirring at 500 r / min for 0.5 - 1 h. After heating, the solution gradually becomes viscous and forms a homogeneous colloidal suspension (apparently without obvious granular feeling), obtaining an injection molding liquid. Utilize the acidic condition to promote the hydrolysis crosslinking of silane without carrying inorganic substances, as well as the thermal crosslinking of borax with phosphonic acid, hydroxyl groups, and carboxyl groups on the surface of wood powder, forming each phase component crosslinked by chemical bonds. Therefore, from the appearance, there are no obvious aggregated particles presented;

[0068] S4. Evaporation for Pore Formation:

[0069] Immediately inject the newly prepared injection molding liquid into the flat groove, heat and evaporate water at 150 °C to obtain a porous plate; the moisture content < 1%, and the porosity is 50.9 - 55.4%;

[0070] S5. Hot Pressing and Forming:

[0071] Use a hot press plate at 0.2 - 0.3 MPa and 125 - 135 °C to hot press the porous plate in the flat groove, keep it warm at 125 - 135 °C for 30 min, trim the edges and grind the edges to obtain the finished PE wood - plastic board. In the anhydrous state and when PE is in a softened state, under the support of inorganic support agents (glass fiber powder, nano - cellulose, and wood powder), utilize the breakage and repair of borate ester bonds to realize the recombination of the cross - linked structure, forming a slightly dense and pressure - resistant permeable PE wood - plastic board finished product, with a porosity of 25 - 30%.

[0072] The basic qualified formula of the obtained PE wood - plastic board finished product includes the following components in parts by weight:

[0073] 100 parts of wood powder (wood powder for wood - plastic products, 60 - 100 mesh, Shijiazhuang Ganshuo Mineral Products Co., Ltd.);

[0074] 30 - 50 parts of silane - modified PE gel: the xylene - swelling gel of silane - modified PE;

[0075] 15 - 20 parts of glass fiber powder (ground powder of waste wind power generation blades);

[0076] 7 - 9 parts of nano - cellulose;

[0077] 2 - 4 parts of borax (Turkish decahydrate borax, content: 99.9%, appearance: white free - flowing crystal particles, Shanghai Yixin Chemical Co., Ltd.);

[0078] 1.5 - 2.5 parts of acrylate resin (toughening agent, LR white acrylic resin, Sigma - Aldrich);

[0079] 3 - 5 parts of PE wax (lubricant, LW - 107 polyethylene wax emulsion, Nanjing Tianshi New Materials Technology Co., Ltd.);

[0080] The specific formula is shown in Table 2 below:

[0081] Table 2.

[0082]

[0083] To verify the influence of the process of the present invention on the pore structure and rapid dehydration performance, the following comparative tests were carried out, mainly to verify the irreplaceability of processes such as acid treatment of wood powder, hydrolysis cross - linking, evaporation pore - forming, and hot pressing.

[0084] Comparative Example 8:

[0085] 1) Preparation of blended PE particles:

[0086] Put the silane - modified PE gel, glass fiber powder, and nanocellulose into a screw extruder. The temperature parameters of the five zones of the screw extruder are: 140 - 160 °C, 160 - 180 °C, 180 - 200 °C, 170 - 190 °C, and 180 - 200 °C. The nozzle temperature is 180 - 200 °C. During the process, air needs to be released to remove xylene; the blended PE particles are obtained by extrusion; through silane grafting, the glass fiber powder, nanocellulose, and silane - modified PE gel are connected by chemical bonds;

[0087] 2) Mixing:

[0088] Mix wood powder and water in a weight ratio of 1:2 - 3, add the blended PE particles, borax, acrylate resin, and PE wax, heat up, and react under closed conditions (equipped with a transparent observation port), at 90 - 120 °C, and 500 r / min stirring for 0.5 - 1 h. After heating, the solution gradually becomes viscous, but there are obvious suspended wood powders on the surface of the solution, and an injection - molding liquid is obtained;

[0089] 3) Evaporation pore - forming:

[0090] Immediately inject the newly prepared injection - molding liquid into a flat groove, heat and evaporate the water at 150 °C to obtain a porous plate; the moisture content < 1%, the porosity is 47.1%. Apparently, compared with Example 2, its surface has more large - pore structures, that is, the cross - linked network is relatively loose, indicating the necessity of acid treatment of wood powder in the present invention, and the acid treatment can also be replaced by the centrifugal liquid in the preparation process of nanocellulose to achieve low - waste production;

[0091] 4) Hot pressing:

[0092] Use a hot pressing plate at 0.2 - 0.3 MPa and 125 - 135 °C to hot press the porous plate in the flat groove, keep it warm at 125 - 135 °C for 30 min, cut and grind the edges to obtain the finished PE wood - plastic board. After hot pressing, most of the large pores collapse, and the porosity rapidly drops to 16.2% (28.6% in Example 2).

[0093] Comparative Example 9:

[0094] 1) Preparation of blended PE particles:

[0095] Put the silane - modified PE gel, glass fiber powder and nanocellulose into a screw extruder. The temperature parameters of the five zones of the screw extruder are: 140 - 160 °C, 160 - 180 °C, 180 - 200 °C, 170 - 190 °C and 180 - 200 °C, and the nozzle temperature is 180 - 200 °C. During the process, it is necessary to vent to remove xylene; extrude to obtain blended PE particles; through silane grafting, make the glass fiber powder, nanocellulose and silane - modified PE gel connected by chemical bonds;

[0096] 2) Acid treatment of wood powder:

[0097] Mix the wood powder and an aqueous H2S04 solution with a mass fraction of 58 - 62% (which can be replaced by the centrifugate in the preparation process of nanocellulose) according to a weight ratio of 1:2 - 3, soak for 12 h, and stir to obtain acidic wood pulp; through acid modification, the wood powder can be made fluffy, thus further promoting the mixing of the wood powder and the PE phase;

[0098] 3) Evaporation to form pores:

[0099] Put the blended PE particles, borax, acrylate resin and PE wax into the acidic wood pulp, immediately inject the mixture into the flat groove after mixing, heat and evaporate the water at 150 °C to obtain a porous plate; the moisture content < 1%, the porosity is 49.3%, and most of them are large - pore structures;

[0100] 4) Hot - press forming:

[0101] Use a hot pressing plate at 0.2 - 0.3 MPa and 125 - 135 °C to hot press the porous plate in the flat groove, keep it warm at 125 - 135 °C for 30 min, cut and grind the edges to obtain the finished PE wood - plastic board. After hot pressing, most of the large pores collapse, and the porosity rapidly drops to 13.7%.

[0102] Comparative Example 10:

[0103] 1) Preparation of blended PE particles:

[0104] Put the silane-modified PE gel, glass fiber powder, and nanocellulose into a screw extruder. The temperature parameters for the five zones of the screw extruder are: 140 - 160 °C, 160 - 180 °C, 180 - 200 °C, 170 - 190 °C, and 180 - 200 °C. The nozzle temperature is 180 - 200 °C. During the process, venting is required to remove xylene; extrude to obtain blended PE pellets; through silane grafting, make the glass fiber powder, nanocellulose, and silane-modified PE gel connected by chemical bonds;

[0105] 2) Acid treatment of wood powder:

[0106] Mix wood powder and an aqueous H2S04 solution with a mass fraction of 58 - 62% (which can be replaced by the centrifugate in the preparation process of nanocellulose) in a weight ratio of 1:2 - 3, soak for 12 h, and stir to obtain acidic wood pulp; through acid modification, the wood powder can be made fluffy, thereby further promoting the mixing of the wood powder and the PE phase;

[0107] 3) Hydrolysis crosslinking:

[0108] Put the blended PE pellets, borax, acrylate resin, and PE wax into the acidic wood pulp, raise the temperature, and react under closed conditions (equipped with a transparent observation port), at 90 - 120 °C, with stirring at 500 r / min for 0.5 - 1 h. After heating, the solution gradually becomes viscous and presents a homogeneous colloidal suspension (apparently without obvious particle sense) to obtain an injection molding liquid; utilize the acidic condition to promote the hydrolysis crosslinking of silane without carrying inorganic substances, and the thermal crosslinking of borax with phosphonic acid, the surface hydroxyl and carboxyl groups of wood powder, etc., to form crosslinked components of each phase through chemical bonds. Therefore, from the appearance, there are no obvious aggregated particles;

[0109] 4) Hot pressing and drying:

[0110] Immediately inject the newly prepared injection molding liquid into a flat groove to obtain a gel plate. Use a hot press plate at 0.2 - 0.3 MPa and 125 - 135 °C to hot press the gel plate, keep it warm at 125 - 135 °C for 30 min to obtain a relatively thick foam board, dry it to a moisture content < 1%, trim the edges and grind the edges to obtain the finished PE wood-plastic board. The measured porosity is 42.5%, but the strength is weak and obvious delamination occurs.

[0111] V. Properties of the environmentally friendly nano-bacteriostatic PE wood-plastic board:

[0112] 1. Detection standards:

[0113] 1) Mechanical properties:

[0114] According to the methods and standards recorded in JC / T 2436 - 2018 Wood-plastic Furniture Boards, test the flexural strength. Not less than 20 MPa is qualified, Shore hardness / HD ≥ 70, and abrasion resistance / (mg / 100r) ≤ 80;

[0115] 2) Water permeability test: The water permeability rate of the permeable wood-plastic board is usually measured by a constant-head permeability test. The water permeability coefficient is calculated by measuring the water flow rate and should not be lower than 0.5 cm / s. During actual construction, it is generally controlled at 4.5 - 6.5 centimeters per second.

[0116] 3) Sunlight dehydration test:

[0117] Under sunlight from 12:00 to 2:00 noon at 30°C, the saturated water-absorbed PE wood-plastic board products suspended are tested to detect the dehydration time (min) when the moisture content ≤ 1%. Generally, it is 1.5 - 2 min. Its fast dehydration speed proves that the main component is hydrophobic. And because the borate ester bond can self-repair when encountering water, the network structure is relatively dense, that is, water directly penetrates through the original pores and it is difficult to penetrate into the cross-linked network of PE / wood powder.

[0118] 4) Antibacterial test: The antibacterial test standard is ASTM E2180, and the selected bacteria are Escherichia coli and Staphylococcus aureus.

[0119] 2. Test results:

[0120] Table 3. Properties of environmentally friendly nano-antibacterial PE wood-plastic boards

[0121]

[0122] As can be seen from Table 3, when comparing Examples 1 - 3 with each other, the content of inorganic components increases, improving hardness, flexural strength and wear resistance, but the corresponding amount of PE used for modification decreases, resulting in the transportation of the cross-linked network. The water permeability coefficient increases, but the dehydration time increases significantly. This may be due to the reduction in the amount of cross-linked network used, leading to easy penetration of water into the phase interface and then difficult removal.

[0123] When comparing Comparative Examples 1 - 2 with Example 2, the lack of vinylphosphonic acid or VBP-Bu ionic liquid reduces the antibacterial rate. At the same time, vinylphosphonic acid also affects the density of the later cross-linked network. Therefore, the dehydration time of Comparative Example 1 increases significantly, and the related strength also decreases.

[0124] When comparing Comparative Examples 3 - 4 with Example 2, it is proved that glass fiber powder and nano-cellulose greatly improve the strength of the wood-plastic board, and at the same time affect the porosity (possibly the supporting effect during the hot pressing process), resulting in a decrease in the water permeability coefficient and an increase in the dehydration time.

[0125] When comparing Comparative Example 5 with Example 2, it shows that borax may play a decisive role in the density of the cross-linked network, which is reflected in the significant increase in the dehydration time.

[0126] Comparing Comparative Examples 6-7 with Example 2 shows that at the same inorganic content, acrylate resin and PE wax are beneficial to improving the uniformity of the organic-inorganic phase distribution, which may affect the uniformity of the pore structure, manifested in the improvement of mechanical properties and the reduction of dehydration time.

[0127] Comparing Comparative Examples 8-9 with Example 2 shows that processes such as acid treatment of wood flour and hydrolysis crosslinking can significantly improve water permeability and reduce dehydration time;

[0128] Comparing Comparative Example 10 with Example 2 shows that the product obtained by hot pressing first and then drying has significantly poor mechanical strength, and it is not easy to dehydrate after the crosslinked network absorbs water.

[0129] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. An environmentally friendly nano-antibacterial PE wood-plastic board, characterized in that: The composition comprises the following components in parts by weight: 100 parts of wood flour; 30-50 parts of silane-modified PE gel: xylene-swollen gel of silane-modified PE; 15-20 parts of glass fiber powder; 7-9 parts of nanocellulose; 2-4 parts of borax; 1.5-2.5 parts of acrylate resin; 3-5 parts of PE wax; The preparation process of the silane-modified PE gel is as follows: PE particles and xylene were mixed and swelled at 80°C for 15 minutes, and vinyl silane, vinyl phosphonic acid, 4-vinylbenzyltributylphosphonium chloride and organic peroxide were added in sequence. The mixture was reacted at 80°C for 3-4 hours to obtain silane-modified PE gel.

2. The environmentally friendly nano-antibacterial PE wood-plastic board according to claim 1, characterized in that: In the preparation process of the silane-modified PE gel, the weight ratio of PE particles, xylene, vinyl silane, vinyl phosphonic acid, 4-vinylbenzyltributylphosphonium chloride and organic peroxide is 100:115-120:2-4:3-5:3-5:0.1-0.

2.

3. The environmentally friendly nano-antibacterial PE wood-plastic board according to claim 1, characterized in that: The vinyl silane is any one of vinyl triethoxy silane, vinyl tri(2-methoxyethoxy) silane and 3-methacryloxypropyl trimethoxy silane.

4. The environmentally friendly nano-antibacterial PE wood-plastic board according to claim 1, characterized in that: The organic peroxide includes any one of diisopropyl peroxide, trivinylmethanetrione peroxide and methylvinylformamide peroxide.

5. The environmentally friendly nano-antibacterial PE wood-plastic board according to claim 1, characterized in that: The production process of the glass fiber powder is as follows: The waste wind turbine blades are crushed and ground into glass fiber powder with a particle size of 100-150 mesh.

6. The environmentally friendly nano-antibacterial PE wood-plastic board according to claim 1, characterized in that: Preparation of the nanocellulose: The bleached kraft eucalyptus pulp is mixed with a H2S04 aqueous solution with a mass fraction of 58-62%, the amount of the H2S04 aqueous solution is 8 ml / g pulp, the reaction temperature is 50-60°C, the reaction time is 30-60 min, and acid wood pulp is obtained. The residue is dried by centrifugal separation to obtain nanocellulose.

7. The method for preparing an environmentally friendly nano-antibacterial PE wood-plastic board according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Preparation of blended PE particles: Putting silane-modified PE gel, glass fiber powder and nanocellulose into a screw extruder and extruding to obtain blended PE particles; connecting the glass fiber powder, nanocellulose and silane-modified PE gel through chemical bonds by silane mounting; S2. Wood powder acid treatment: The wood powder and the H2S04 aqueous solution with a mass fraction of 58-62% are mixed in a weight ratio of 1:2-3, soaked for 12 hours, and stirred to obtain acidic wood pulp; the wood powder can be made fluffy by acid modification, thereby further promoting the mixing of the wood powder and the PE phase; S3, hydrolysis cross-linking: Putting blended PE particles, borax, acrylic resin and PE wax into acidic wood pulp, heating, and reacting for 0.5-1h under closed conditions at 90-120°C and 500r / min stirring to obtain injection molding liquid; S4, evaporation hole making: The newly prepared injection molding liquid was immediately injected into the flat groove and heated at 150°C to evaporate and remove water to obtain a porous plate; S5, hot pressing molding: The porous plate in the flat groove is hot-pressed by a hot pressing plate at 0.2-0.3MPa and 125-135°C, kept at 125-135°C for 30 minutes, and trimmed and ground to obtain a finished PE wood-plastic plate.

8. The method for preparing an environmentally friendly nano-antibacterial PE wood-plastic board according to claim 7, characterized in that: The five-zone temperature parameters of the screw extruder in S1 are: 140-160°C, 160-180°C, 180-200°C, 170-190°C and 180-200°C, the nozzle temperature is 180-200°C, and the process requires venting to remove xylene.

Images