A method for preparing a multi-component composite co-extrusion material with high interface strength

Abstract

The present invention discloses a method for preparing a multi-component composite co-extruded material with high interfacial strength. The method comprises drying a wood or bamboo surface substrate, generating a uniformly distributed water mist film on the surface of the substrate, causing the surface to absorb water, and instantaneously vaporizing the water mist film to loosen the surface; then introducing the substrate into a co-extrusion mold, sequentially co-extruding an adhesive layer, a wood-plastic shell layer, and a multifunctional modified plastic surface layer on the surface, and finally cooling and shaping the multi-component composite co-extruded material. The multi-component composite co-extruded material with high interfacial strength prepared by the present invention has a stable structure and fundamentally changes the three fatal shortcomings of wood-plastic composite materials, namely, easy creep, high brittleness, and poor thermal stability. At the same time, the wood-plastic composite material is endowed with new anti-aging, wear-resistant, scratch-resistant, impact-resistant, and anti-slip properties, achieving complementary advantages between materials at all levels, expanding the application range of the wood-plastic composite material, and showing a very broad market prospect in high value-added fields.

Description

Technical Field

[0001] The present invention relates to the field of material preparation, and in particular to a method for preparing a multi-component composite co-extrusion material with high interface strength. Background Art

[0002] Recently, a new type of environmentally friendly wood-plastic / wood composite co-extrusion material has entered people's field of vision. With its characteristics of light weight, high strength, creep resistance and non-brittle fracture, good comprehensive performance, green environmental protection, and high cost performance, it has outstanding advantages in high-quality doors and windows, building formwork, large-span components, building parts, multi-functional walls, green buildings, and other applications with high requirements on environmental protection, load-bearing capacity, waterproof and moisture-proof, anti-corrosion and anti-termite, weather resistance and other performance of materials, especially those with high requirements on comprehensive performance. The market space is worth hundreds of billions of yuan and the application prospects are broad.

[0003] However, with the continuous promotion and application of wood-plastic / wood composite co-extrusion materials, it is found that there are still some unresolved technical problems that restrict the further development of such products, such as:

[0004] (1) Among the existing wood-plastic / wood composite co-extrusion materials, the shell layer of wood-plastic composite materials has deficiencies in anti-aging, wear resistance, scratch resistance, impact resistance and anti-slip performance, making its products unsuitable for practical application.

[0005] (2) The wood surface has a high polarity, while the polyolefin enriched on the surface of the polyolefin wood plastic is hydrophobic. The two are incompatible. The wood plastic shell and the wood core layer in the wood plastic / wood composite co-extrusion material are only physically hinged together, and no stronger covalent bond and hydrogen bond force is formed. Due to the large difference in thermal expansion coefficient between the wood plastic shell and the wood core, the product is easily cracked and debonded by the large fluctuations in ambient temperature and humidity and long-term dynamic loads during actual application, which greatly shortens the service life of the wood plastic / wood composite co-extrusion material.

[0006] (3) The natural defects on the wood surface (burls, gums, streaks, scars, etc.) cause local differences in the surface material properties. When they are compounded with the wood-plastic melt in the co-extrusion mold, they easily lead to unstable flow of the wood-plastic melt, which greatly limits the extrusion rate of the wood-plastic / wood composite co-extrusion material, making it very far from the goal of industrial-level high-speed extrusion. Summary of the Invention

[0007] The object of the present invention is to overcome at least one of the shortcomings of the prior art and to provide a method for preparing a multi-component composite co-extruded material with high interface strength.

[0008] The technical solution adopted by the present invention is:

[0009] The present invention provides a method for preparing a multi-component composite co-extruded material with high interfacial strength. The multi-component composite co-extruded material comprises, from the outside to the inside, a multifunctional modified plastic surface layer, a wood-plastic shell layer, an adhesive layer, and a wood or bamboo core layer, comprising the following steps:

[0010] 1) Dry the wood or bamboo substrate within 1-2mm of the surface to a moisture content of less than 0.5%;

[0011] 2) Use an atomizer to generate a uniformly distributed 0.1-0.5mm thick water mist film on the surface of the dried wood or bamboo and make the surface absorb water;

[0012] 3) Instantly vaporize the surface moisture of wood or bamboo, making the surface of wood or bamboo loose;

[0013] 4) introducing the material into a co-extrusion die, applying adhesive on the surface of the wood or bamboo material, adding the wood-plastic shell material and the multifunctional modified plastic surface material for composite co-extrusion, and cooling the material to obtain a multi-component composite co-extrusion material;

[0014] The adhesive consists of 50-80 parts by mass of a polyolefin matrix, 5-30 parts by mass of an adhesive polymer, 15-25 parts by mass of a thermoplastic elastomer and an appropriate amount of a heat stabilizer. The adhesive has a melt index of 2-10 g / 10 min at 190° C. / 2.16 kg.

[0015] In some examples, the multifunctional modified plastic surface layer has a melt index of 0.01 to 5 g / 10 min at 190° C. / 2.16 kg.

[0016] In some examples, in step 1), an infrared dryer is used to rapidly dry the wood or bamboo substrate within a depth of 1 to 2 mm to a moisture content of less than 0.5% within 10 to 55 seconds.

[0017] In some examples, the multifunctional modified plastic surface layer is composed of 60 to 85 parts by mass of a polyolefin matrix, 10 to 25 parts by mass of an ionomer, 4 to 15 parts by mass of a thermoplastic elastomer, 0.5 to 5 parts by mass of a nano-metal oxide, 0.1 to 0.5 parts by mass of an antioxidant, and 0.1 to 1.0 parts by mass of a UV absorber.

[0018] In some examples, the interfacial bonding strength between the wood or bamboo core layer and the wood-plastic shell layer in the multi-component composite co-extruded material is not less than 2.5 MPa.

[0019] In some examples, the interface bonding strength between the wood-plastic shell layer and the multifunctional modified plastic surface layer is not less than 2.0 MPa.

[0020] In some examples, the thickness error of the wood-plastic shell layer in the multi-component co-extruded material is less than 0.2 mm.

[0021] In some examples, in step 3), microwave treatment is used to vaporize the surface moisture of the wood or bamboo within 0.1 to 1.0 seconds.

[0022] In some examples, the thickness of the adhesive layer is 0.1-0.8 mm, and the thickness of the wood-plastic shell layer is 1.5-4.0 mm.

[0023] In some examples, the thickness of the multifunctional modified plastic surface layer is 0.5 to 1.5 mm.

[0024] The beneficial effects of the present invention are:

[0025] 1) A multi-component co-extrusion material with high interfacial strength is prepared by co-extruding a high-performance, multifunctional modified plastic surface layer, a wood-plastic shell layer, an adhesive layer, and a wood or bamboo core layer. The multifunctional modified plastic surface layer serves as the composite's "skin," providing excellent resistance to aging, wear, scratching, impact, and slip, as well as decorative properties. The wood-plastic shell layer provides the composite's "body," imparting a certain degree of hardness, strength, and protective rigidity, while also endowing it with environmentally friendly and economical properties. The lightweight, high-strength wood or bamboo core layer serves as the composite's "skeleton," providing sufficient strength, toughness, and creep resistance, fundamentally addressing the three critical drawbacks of wood-plastic composites: susceptibility to creep, brittleness, and poor thermal stability. These three components each play their respective roles, complementing each other's strengths and expanding the application range of wood-plastic composites, giving them a promising market prospect in high-value-added sectors.

[0026] 2) The present invention can precisely control the amount of water that enters the surface of the wood or bamboo material, ensuring a loosening effect during subsequent microwave treatment. Furthermore, it ensures that the moisture content of the wood or bamboo surface after microwave treatment is substantially consistent with that of the interior, without affecting the subsequent use of adhesives. This significantly improves the production stability and efficiency of multi-component composite co-extrusion materials, enabling them to meet the needs of industrial production.

[0027] 3) By loosening the surface of wood or bamboo, the adhesive can penetrate the wood or bamboo quickly, thereby improving both the interface bonding performance and production efficiency.

[0028] 4) Improve the centering effect of wood or bamboo in multi-composite co-extrusion materials, so that the product has better structural stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Detailed dimensional diagram of the multi-component composite co-extruded material prepared in Example 1.

[0030] Figure 2 This is a detailed dimensional diagram of the multi-component composite co-extruded material prepared in Comparative Example 4. DETAILED DESCRIPTION

[0031] The following disclosure provides many different embodiments or examples for implementing different solutions of the present invention.

[0032] A method for preparing a multi-component composite co-extrusion material with high interfacial strength comprises the following steps: loosening the surface of wood or bamboo, three-step centering of the wood or bamboo, multi-layer composite co-extrusion in a mold, and cooling and shaping. The specific steps are as follows:

[0033] The process of loosening the surface of wood or bamboo:

[0034] 1) Use one or more infrared dryers in series to rapidly dry the wood or bamboo surface within 1-2 mm to a depth of less than 0.5% moisture content within 10-55 seconds. The coverage length of a single infrared dryer is 0.5 m. The higher the surface density of the wood or bamboo, the more infrared dryers are needed in series. Adjusting the feed rate of the wood or bamboo will extend the drying time.

[0035] 2) Use one or more atomizers connected in series to generate a uniformly distributed water mist film with a thickness of 0.1 to 0.5 mm on the surface of the wood or bamboo. A portion of the water is then rapidly introduced into the drying layer described in 1) along the moisture channels within the wood or bamboo cells, creating a gradient distribution within the drying layer with high surface moisture content and low internal moisture content. The coverage length of a single atomizer is 0.3 m. The greater the surface density of the wood or bamboo, the more atomizers are required in series. Adjusting the feed rate of the wood or bamboo to extend the time it takes for water to penetrate the wood or bamboo interior will result in a more pronounced moisture gradient.

[0036] 3) Utilizing a 24 kW high-power microwave, the water within a depth of 1 to 2 mm on the surface of the wood or bamboo described in 2) is vaporized within 0.1 to 1.0 seconds. Within the water channels of the wood or bamboo cells, the vaporized water is blocked by the liquid water in the channels and the water mist film on the surface, creating a "blasting" effect on the wall, thereby loosening the surface.

[0037] Three-step centering process for wood or bamboo:

[0038] 1) A crawler-type tractor with a concave module is used as the wood or bamboo material conveyor, achieving the first step of centering the wood or bamboo. The width of the module's concave shape, after the upper and lower crawlers are pressed together, matches the cross-sectional width of the wood or bamboo, limiting horizontal swing. The lower crawler can be fixed vertically along four columns fixed to the base, constraining the vertical position of the wood or bamboo.

[0039] 2) At the front end of the wood or bamboo material feed port of the co-extrusion die, horizontal and vertical compulsory guide rollers are used to perform the second step of centering on the wood or bamboo. The purpose is to eliminate the negative effects of the original stress and moisture deformation of the wood or bamboo on the centering effect together with the previous heating process.

[0040] 3) In the inner cavity of the wood or bamboo feed port of the co-extrusion die, horizontal and vertical embedded centering rollers with spring pressure correction systems are used to perform the third step of centering on the wood or bamboo. The purpose is to eliminate the negative impact of uneven melt pressure on the centering effect when the wood or bamboo is subjected to different sides in the subsequent multi-layer composite stage.

[0041] Multi-layer co-extrusion process in the mold:

[0042] After the three-step centering treatment, the wood or bamboo material is sequentially extruded into the adhesive layer, the wood-plastic shell layer and the multifunctional modified plastic surface layer in the co-extrusion mold.

[0043] The finally formed multi-component composite co-extruded material is cooled and shaped in a cold mold to complete the preparation of a multi-component composite co-extruded material with high interface strength.

[0044] Example 1:

[0045] The core uses a surface density of 0.42g / cm 3 Poplar laminated veneer lumber (LVL). During the surface loosening process, a single infrared dryer was used for surface drying and a single atomizer for surface moisture infiltration. The LVL feed rate was adjusted to 2.0 m / min, resulting in a drying time of 15 seconds in the dryer and a moisture infiltration time of 9 seconds in the atomizer. A 24 kW high-power microwave was used to instantly vaporize the surface within 0.5 seconds, achieving surface loosening.

[0046] After the three-step centering treatment, the LVL is sequentially extruded into the adhesive layer, the wood-plastic shell layer and the multifunctional modified plastic surface layer in the co-extrusion mold. First, the granulated adhesive particles were added into the hopper of a GMGJ-25 single-screw extruder, melted in the screw barrel, and then co-extruded with LVL. The feed rate was controlled at 5.0±0.1 kg / hour, and the thickness of the adhesive co-extruded layer was 0.2 mm. The composition formula of the adhesive was: 70 parts by mass of high-density polyethylene (HDPE, model 5000S), 10 parts by mass of carboxyl ternary vinyl chloride resin (model Hanwha TP-400M), 10 parts by mass of ethylene-methacrylic acid copolymer (model Dow 3002), 9.5 parts by mass of modified styrene elastomer (melt index of approximately 480 g / 10 min (190°C / 2.16 kg)) and 0.5 parts by mass of calcium zinc heat stabilizer (model CZ-70). The melt index of the adhesive system was approximately 3.5 g / 10 min (190°C / 2.16 kg).

[0047] Subsequently, the granulated wood-plastic particles were added to the hopper of the SJZ65 / 132 counter-rotating conical twin-screw main extruder, melted in the screw barrel, and co-extruded with the adhesive-coated LVL. The feed rate was 97.5±0.5 kg / hour, and the thickness of the wood-plastic co-extrusion layer was 3.0 mm. The composition formula of the wood-plastic was: 50 parts by mass of HDPE (model 5000S), 45 parts by mass of poplar wood powder, 3 parts by mass of maleic anhydride grafted polyolefin (MAPE) and 2 parts by mass of PA03 lubricant.

[0048] Finally, the granulated multifunctional modified plastic particles were added to the hopper of a GMGJ-35 single-screw extruder, melted in the screw barrel, and co-extruded with the wood-plastic-adhesive-coated LVL. The feed rate was 22.5±0.2 kg / hour, and the thickness of the multifunctional modified plastic surface layer was 0.8 mm. The composition formula of the multifunctional modified plastic surface layer was: 70 parts by mass of HDPE (model 100S), 15 parts by mass of ion polymer (model Surlyn 9910), 12 parts by mass of thermoplastic elastomer SEPS (model I480DT-A01), 2 parts by mass of nano-titanium dioxide (model AEROXIDE P25), 0.5 parts by mass of antioxidant (model Irganox B215) and 0.5 parts by mass of UV absorber (model Tinuvin326). The melt index of the multifunctional modified plastic surface layer was approximately 1.2 g / 10 min (190℃ / 2.16 kg).

[0049] The multi-component co-extruded material is cooled and shaped in a cold mold. The overall cross-sectional size of the prepared multi-component co-extruded material is 122mm×30mm (length×width). The detailed size distribution of each layer is as follows: Figure 1 shown.

[0050] Example 2:

[0051] The core uses a surface density of 0.65g / cm 3 Glued bamboo lumber (GLB). During the surface loosening process, two infrared dryers were connected in series for surface drying, and two atomizers were connected in series for surface moisture infiltration. The water output of each atomizer was reduced, so that the total amount of moisture entering the GLB remained the same as in Example 1. The GLB feed rate was adjusted to 2.0 m / min, resulting in a drying time of 30 seconds in the dryer zone and a moisture infiltration time of 18 seconds in the atomizer zone. All other preparation processes were the same as in Example 1.

[0052] Example 3:

[0053] The core uses a surface density of 0.42g / cm 3 Poplar laminated veneer lumber (LVL). During the surface loosening process, two infrared dryers were used in series to dry the surface layer, with the LVL drying time in the dryer zone being 30 seconds. All other preparation processes were the same as in Example 1.

[0054] Example 4:

[0055] The core uses a surface density of 0.42g / cm 3 Poplar laminated veneer lumber (LVL). During the surface loosening process, two atomizers were used to wet the surface, ensuring that the LVL was wetted in the atomizer area for 18 seconds. All other preparation processes were the same as in Example 1.

[0056] Comparative Example 1:

[0057] The core uses a surface density of 0.42g / cm 3 Poplar laminated veneer lumber (LVL). The LVL did not undergo a surface loosening process; instead, the adhesive layer, the wood-plastic shell layer, and the multifunctional modified plastic surface layer were co-extruded directly in a co-extrusion mold. All other preparation processes were the same as in Example 1.

[0058] Comparative Example 2:

[0059] The core uses a surface density of 0.42g / cm 3 Poplar laminated veneer lumber (LVL) was mechanically loosened to a depth of 1-2 mm using a gear roller cutter. The LVL substrate was then introduced into a coextrusion die for sequential coextrusion of the adhesive layer, the wood-plastic shell layer, and the multifunctional modified plastic surface layer. The remaining preparation processes were identical to those in Example 1.

[0060] Comparative Example 3:

[0061] The core uses a surface density of 0.42g / cm3 Poplar laminated veneer lumber (LVL). The adhesive composition was changed to: 85 parts by mass of high-density polyethylene (HDPE, model 5000S), 5 parts by mass of carboxyl ternary vinyl acetate resin (model Hanwha TP-400M), 9.5 parts by mass of ethylene-methacrylic acid copolymer (model Dow 3002), and 0.5 parts by mass of calcium zinc heat stabilizer (model CZ-70). The melt index of the adhesive system was approximately 1.5 g / 10 min (190°C / 2.16 kg). The rest of the preparation process was the same as in Example 1.

[0062] Comparative Example 4:

[0063] The core uses a surface density of 0.42g / cm 3 Poplar veneer laminated lumber (LVL). The wood-plastic / LVL co-extruded composite material, without an adhesive layer or a multifunctional modified plastic surface layer, has a shell wood-plastic formulation of 50 parts by mass of HDPE (model 5000S), 45 parts by mass of poplar wood powder, 3 parts by mass of maleic anhydride grafted polyolefin (MAPE), and 2 parts by mass of PA03 lubricant. The overall cross-sectional dimensions of the prepared wood-plastic / LVL co-extruded composite material are 122mm × 30mm (length × width). The detailed size distribution is shown in the figure below. Figure 2 shown.

[0064] During the co-extrusion composite production process, the pelletized wood-plastic granules are added to the hopper of an SJZ65 / 132 counter-rotating conical twin-screw main extruder. After being melted in the screw barrel, they are combined with the core LVL in the co-extrusion die and overmolded. The LVL feed rate and the rear haul-off speed are adjusted to 0.6 m / min to ensure uniform extrusion speed.

[0065] Performance Testing

[0066] To better illustrate the present invention, the performance of the multi-component composite co-extruded materials with high interface strength obtained in each embodiment is tested below. The standard testing methods in the industry are used to test the products' interface bonding performance, dimensional stability, anti-aging performance, surface wear resistance and surface anti-slip performance, and comparison is made with comparative examples.

[0067] Interface bonding performance test: According to the standard GB / T 17657, the bonding strength test of the WPC / wood or bamboo interface and the WPC / multifunctional modified plastic surface interface was carried out in sequence. The co-extruded composite material was sawn into 50mm × 50mm × 30mm (length × width × thickness) samples, and the multifunctional modified plastic surface was sliced ​​with a circular milling cutter to form a 1000mm 2The circular area is bonded to the fixture, and the interface bonding strength between the wood-plastic and multifunctional modified plastic surface is tested using a universal mechanical testing machine; after the above test, the sample is sliced ​​into the inner wood-plastic shell with a circular milling cutter to form a 1000mm 2 The circular area is bonded to the fixture again, and the universal mechanical testing machine is used to test the interface bonding strength between the wood-plastic and wood or bamboo.

[0068] Dimensional stability test: The end-capped co-extruded composite material was subjected to a hot water immersion test in accordance with GB / T 17657. The specific test method is as follows:

[0069] 1) Five 100 mm samples were cut along the length of the co-extruded composite material and dried in a 50° C. oven for more than 72 hours, followed by end-capping with the adhesive of Examples 1 to 4 or Comparative Examples 1 to 2;

[0070] 2) Soak the capped sample in 80°C hot water for 4 hours, remove the sample and cool it in deionized water at 25±2°C for 15 minutes;

[0071] 3) Finally, the sample was placed in an oven at 63°C and dried for 20 hours. After completing one cycle, the thickness, width, and length of the sample were measured.

[0072] The volume change rate of the examples and comparative examples was measured after 6 cycles of testing.

[0073] Anti-aging performance testing: 80mm × 12mm × 4mm (length × width × thickness) samples were cut from the coextruded layer of the coextruded composite material and subjected to UV accelerated aging testing according to the aging procedure set in accordance with the ASTM G-154 standard. The aging process was carried out in a 12-hour cycle, during which the sample underwent three stages of UV irradiation, spraying, and condensation. The UV irradiation stage simulated the damage caused by daylight and temperature to the material. The wavelength was set to 310 nm and the irradiation intensity was set to 0.71 W / m 2 The irradiation time was set to 8 hours and the temperature was set to 60°C. The spraying phase simulated the effects of rain on the material, with a spraying time of 15 minutes and no temperature control. The condensation phase simulated the effects of high humidity at night on the material. The humidity in the chamber was brought to 100% using a heated water tank. The condensation time was 3.75 hours and the temperature was set to 50°C. In the continuous cycle test, samples were removed after 3000 hours of aging and tested for notched impact properties according to ASTM D256-02 to determine the impact strength retention rate.

[0074] Surface abrasion resistance testing: According to ISO 7784.2, specimens measuring 100mm × 122mm × 30mm (length × width × thickness) were cut from the coextruded composite material along its length. A 6mm diameter circular hole was drilled in the center of the specimen. The abrasion resistance of the material was tested using a JM-V abraser. The abrasion resistance of 180# sandpaper against a standard zinc plate was 82.7mg / 500r. Before testing, the sample was scraped clean of excess material around the perimeter and the center hole with a knife. The sample surface was then cleaned with a high-pressure air gun, wiped with alcohol, and allowed to dry. The initial sample mass, M0, was then measured on a 1 / 10,000 scale. The turntable speed was set to 60r / min, and the weight was 1000g. After the test, the sample was cleaned with a high-pressure air gun, and the abraded sample mass, M1, was measured on a 1 / 10,000 scale. The abrasion value was calculated using the difference method.

[0075] Surface anti-slip performance testing: Surface anti-slip performance was tested using a pendulum-type friction coefficient tester, referring to the standard GB / T 24508 "Wood Plastic Flooring." Samples measuring 1000 mm × 122 mm × 30 mm (length × width × thickness) were cut along the length of the co-extruded composite material, with a calibrated sliding length of 76 mm. Before testing, the test surface was zeroed by three swings in the air. Deionized water was then sprayed on the test surface to form a continuous water film. The test room temperature was maintained at 23 ± 1°C and the humidity at 50 ± 3%. Five different points on each sample were tested, and the anti-slip values ​​were recorded on the scale. The test results are shown in Table 1.

[0076] Table 1. Performance test results

[0077]

[0078] Among them, bonding strength 1 refers to the bonding strength between the WPC / wood or WPC / bamboo interface, and bonding strength 2 refers to the bonding strength between the WPC / multifunctional modified plastic interface. The unit of bonding strength is MPa.

[0079] By comparing the test results of the wood-plastic / wood or wood-plastic / bamboo interface bonding strength and volume change rate of the composite co-extruded materials prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 4, it can be seen that by loosening the surface of the wood or bamboo material and then co-extruding the adhesive layer, high-strength bonding can be achieved at the interface between the polyolefin-based wood-plastic composite material and the wood or bamboo material, making the structure of the multi-component composite material more stable, and the sample shows a lower volume change rate in the hot water immersion test.

[0080] A comparative study of the interfacial bonding strength test results of the wood-plastic / wood or wood-plastic / bamboo composites prepared in Examples 1, 2, 3, and 4 reveals that the wood or bamboo surface loosening process significantly impacts the interfacial bonding strength of the wood-plastic / wood or wood-plastic / bamboo composites. The greater the surface density of the wood or bamboo, the longer the surface drying and water soaking time required for loosening. However, excessive drying, which increases the depth of the dry layer, and excessive water soaking into the wood or bamboo surface during atomization, both reduce interfacial bonding strength, thereby reducing the structural stability of the composite.

[0081] By comparing the test results of the wood-plastic / LVL interface bonding strength of the multi-component composite co-extruded materials prepared in Example 1 and Comparative Example 2, it can be seen that mechanically loosening the surface of the wood or bamboo substrate with a gear roller will destroy the cell structure of the wood or bamboo matrix, thereby reducing the interface bonding strength of the wood-plastic / wood or wood-plastic / bamboo after bonding.

[0082] A comparative study of the WPC / LVL interfacial bonding strength test results for the multi-component co-extruded materials prepared in Example 1 and Comparative Example 3 shows that the melt index of the adhesive system significantly influences the WPC / wood or WPC / bamboo interfacial bonding strength. The lower the melt index, the less effective the adhesive melt is at penetrating the wood or bamboo, resulting in lower WPC / wood or WPC / bamboo interfacial bonding strength. To ensure the coextrusion process is met, the adhesive's melt index at 190°C / 2.16 kg should be controlled between 2 and 10 g / 10 min.

[0083] The interface bonding strength of the wood-plastic / multifunctional modified plastic surface layer of the multi-component composite co-extruded materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was studied. It can be seen that the wood-plastic composite materials of the multifunctional plastic surface layer and the shell layer prepared by the present invention exhibit excellent interface bonding performance, and the bonding strength is not less than 2.0 MPa.

[0084] By comparing the anti-aging performance tests, surface wear resistance and surface anti-slip performance tests of the multi-component composite co-extruded materials prepared in Examples 1 to 4, Comparative Examples 1 to 3 and the composite co-extruded material prepared in Comparative Example 4, it can be seen that the multifunctional modified plastic surface layer provides the multi-component composite co-extruded material with excellent anti-aging, wear resistance, anti-slip and decorative properties.

[0085] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions that do not depart from the concept of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-component composite co-extruded material with high interfacial strength, wherein the multi-component composite co-extruded material comprises, from the outside to the inside, a multifunctional modified plastic surface layer, a wood-plastic shell layer, an adhesive layer, and a wood or bamboo core layer, characterized in that: The following steps are involved: 1) Dry the wood or bamboo substrate within 1-2mm of the surface to a moisture content of less than 0.5%; 2) Use an atomizer to generate a uniformly distributed 0.1-0.5mm thick water mist film on the surface of the dried wood or bamboo and make the surface absorb water; 3) Instantly vaporize the surface moisture of wood or bamboo within 0.1 to 1.0 seconds, loosening the surface of the wood or bamboo; 4) introducing the wood or bamboo material with loosened surface into the co-extrusion die, co-extruding and coating the surface of the wood or bamboo material with adhesive, adding the wood-plastic shell material and the multifunctional modified plastic surface material for co-extrusion, and cooling to obtain the multi-component composite co-extrusion material; The adhesive is composed of 50 to 80 parts by mass of a polyolefin matrix, 5 to 30 parts by mass of an adhesive polymer, 15 to 25 parts by mass of a thermoplastic elastomer and an appropriate amount of a heat stabilizer. The melt index of the adhesive at 190°C / 2.16kg is 2 to 10 g / 10min. The multifunctional modified plastic surface layer is composed of 60 to 85 parts by mass of a polyolefin matrix, 10 to 25 parts by mass of an ion polymer, 4 to 15 parts by mass of a thermoplastic elastomer, 0.5 to 5 parts by mass of a nano-metal oxide, 0.1 to 0.5 parts by mass of an antioxidant and 0.1 to 1.0 parts by mass of a UV absorber.

2. The preparation method according to claim 1, characterized in that The multifunctional modified plastic surface layer has a melt index of 0.01 to 5 g / 10 min at 190° C. / 2.16 kg.

3. The preparation method according to claim 1, characterized in that In the step 1), an infrared dryer is used to rapidly dry the wood or bamboo substrate within a depth of 1 to 2 mm on the surface to a moisture content of less than 0.5% within 10 to 55 seconds.

4. The preparation method according to claim 1, characterized in that The interfacial bonding strength between the wood or bamboo core layer in the multi-component composite co-extrusion material and the wood-plastic shell layer is not less than 2.5 MPa.

5. The preparation method according to claim 1, characterized in that The interface bonding strength between the wood-plastic shell layer and the multifunctional modified plastic surface layer is not less than 2.0 MPa.

6. The preparation method according to claim 1, characterized in that The thickness error of the wood-plastic shell layer in the multi-component composite co-extrusion material is less than 0.2 mm.

7. The preparation method according to claim 1, characterized in that In the step 3), the vaporization process is to use microwave treatment to vaporize the surface moisture of the wood or bamboo within 0.1 to 1.0 seconds.

8. The preparation method according to claim 1, characterized in that The thickness of the adhesive layer is 0.1-0.8 mm, and the thickness of the wood-plastic shell layer is 1.5-4.0 mm.

9. The preparation method according to claim 1, characterized in that The thickness of the multifunctional modified plastic surface layer is 0.5 to 1.5 mm.

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