Thermoplastic regenerated plastic and plant straw composite board and preparation method thereof

Abstract

The invention relates to the technical field of C08L97 / 00, in particular to a thermoplastic reprocessed plastic and plant straw composite board and a preparation method thereof.The thermoplastic reprocessed plastic and plant straw composite board is at least prepared from, by weight, 20-60 parts of thermoplastic reprocessed plastic, 30-70 parts of plant straw, 1-5 parts of compatilizer, 1-5 parts of lubricant, 0.1-1 part of antioxidant, 0.1-1 part of ultraviolet light absorber and 0-3 parts of pigment; the plate product with excellent performance is prepared by compounding the thermoplastic regenerated plastic and the plant straws, so that the problem of pollution of agricultural residual films to soil is solved, and pollution to the atmospheric environment caused by incineration of cotton straws is avoided; the waste is turned into wealth, and a new utilization way is opened up for comprehensive reutilization of the agricultural residual films and the plant straws.

Description

Technical Field

[0001] The invention relates to the technical field of C08L97 / 00, in particular to a composite board of thermoplastic recycled plastics and plant straw and a preparation method thereof. Background Art

[0002] According to relevant statistics, my country, as a major agricultural country, generates more than 700 million tons of straw each year, with an utilization rate of less than 70%. More than 200 million tons cannot be processed each month, becoming "waste" that is "not very useful" but must be disposed of. The comprehensive utilization of straw is of great significance to promoting farmers' income, environmental protection, resource conservation and sustainable development of the agricultural economy. In recent years, my country has made certain progress in the comprehensive utilization of straw, and the comprehensive utilization rate has steadily increased. However, the comprehensive utilization of straw also faces some challenges in equipment, technology, and processes in industrial production during its promotion. In order to better promote the comprehensive utilization of straw, the comprehensive utilization methods of straw tend to be diversified. It is also through continuous exploration and innovation of the technology and methods of comprehensive utilization of straw, further improving the utilization value of straw, reducing resource waste and environmental pollution, and promoting the development of the comprehensive utilization industry of straw.

[0003] Agricultural plastic mulch has become an important means for Chinese farmers to generate income. However, after years of use, the utilization rate of agricultural residual film in the application after collection has been low. Waste plastic residual film is not easy to decompose in the soil and is easily blown away by the wind, causing pollution to the ecological environment. It also blocks the connectivity of soil pores, reduces soil permeability and water permeability, and affects soil microbial activity and soil fertility. In addition, residual film may entangle crop roots, affecting the root system's absorption of water and nutrients, leading to poor crop growth, reduced yields, or even crop failure.

[0004] Therefore, how to comprehensively utilize waste plant straw and waste plastic film to simultaneously achieve high-value utilization of plant straw and waste plastic film has important practical significance. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a composite board of thermoplastic recycled plastic and plant straw. The thermoplastic recycled plastic and plant straw are compounded to prepare a board product with excellent performance. It not only solves the problem of soil pollution caused by agricultural film residues, but also avoids the pests and diseases caused by crushing and returning cotton straw to the field, thereby improving the economy of cotton straw; it realizes the transformation of waste into treasure, and also opens up a new utilization path for the comprehensive reuse of agricultural film residues and plant straw.

[0006] On the one hand, the present invention provides a thermoplastic recycled plastic and plant straw composite board. The raw materials for preparation include at least 20-60 parts of thermoplastic recycled plastic, 30-70 parts of plant straw, 1-5 parts of compatibilizer, 1-5 parts of lubricant, 0.1-1 parts of antioxidant, 0.1-1 parts of ultraviolet absorber and 0-3 parts of pigment, calculated by weight.

[0007] As a preferred technical solution, the method for preparing the thermoplastic recycled plastic is: the recycled waste thermoplastic plastic products are subjected to crushing, impurity removal and granulation in sequence.

[0008] Preferably, the recycled waste thermoplastic plastic products are residual agricultural films.

[0009] Preferably, the crushing device is a semi-supported shaft knife type crushing device.

[0010] Preferably, the impurity removal device is an anhydrous impurity removal device.

[0011] As a preferred technical solution, the length of the plant straw is ≤10 cm, preferably ≤5 cm, and most preferably ≤3 cm.

[0012] As a preferred technical solution, the mass ratio of the thermoplastic recycled plastic to the plant straw is (45-55):(40-50), preferably (46-50):(42.3-46.5).

[0013] As a preferred technical solution, the plant straw is crop straw, selected from at least one of cotton straw, corn straw, soybean, and wheat straw.

[0014] As a preferred technical solution, the compatibilizer is selected from at least one of epoxy type, carboxylic acid type and anhydride type, preferably anhydride type.

[0015] Preferably, the compatibilizer is maleic anhydride.

[0016] Preferably, the amount of the compatibilizer added is more than 4.5% of the mass of the plant straw. Preferably, the amount of the compatibilizer added is 4.8-5.5%, preferably 5.0-5.2% of the mass of the plant straw.

[0017] As a preferred technical solution, the lubricant is selected from at least one of amides, stearic acid and its derivatives, preferably at least one of stearic acid and stearate.

[0018] As a preferred technical solution, the amount of the lubricant added is less than 4.8% of the mass of the thermoplastic recycled plastic. Preferably, the amount of the compatibilizer added is 4.0-4.5%, preferably 4.3-4.4%, of the mass of the thermoplastic recycled plastic.

[0019] As a preferred technical solution, the antioxidant is selected from at least one of hindered phenol antioxidants, phosphite antioxidants, and hindered amine (HALS) antioxidants, preferably hindered phenol antioxidants.

[0020] Preferably, the antioxidant is antioxidant 1010.

[0021] As a preferred technical solution, the ultraviolet absorber is selected from at least one of a benzotriazole ultraviolet absorber and a benzophenone ultraviolet absorber, and is preferably a benzophenone ultraviolet absorber.

[0022] Preferably, the ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone (UV-531).

[0023] As a preferred technical solution, the mass ratio of the antioxidant to the ultraviolet absorber is 1:(1-2), preferably 1:(1-1.5), and most preferably 1:(1.25-1.5).

[0024] The purpose of the present invention is to accelerate the pace of industrialization of the comprehensive utilization of crop straw and agricultural waste film, broaden the application field, improve the added value of crop straw and waste film products and the product practicality and market competitiveness, realize the recycling and reuse of crop straw and agricultural waste film, and commercialize them, promote resource conservation, environmental protection, and sustainable development, which not only brings economic benefits, but also forms good environmental benefits.

[0025] Specifically, the present invention prepares thermoplastic recycled plastic by crushing the residual film of farmland and granulating it after anhydrous impurity removal treatment, and coordinates the control of plant straw length and the mass ratio of thermoplastic recycled plastic and plant straw in the system, so that the water absorption rate of the prepared composite board is low, and it has excellent processability, compressive strength and elastic modulus, and better meets the actual application needs. In particular, the mass ratio of thermoplastic recycled plastic and plant straw is controlled to (45-55): (40-50), and the addition amount of maleic anhydride, stearic acid, antioxidant and ultraviolet absorber in the system is controlled, so that the compressive strength of the provided composite board is as high as 28MPa or more, the elastic modulus is as high as 4000MPa or more, and the water absorption rate is below 1.8%, the board is well formed, has no bubbles, has a smooth surface, and has a high yield.

[0026] The composite board provided by the present invention is mainly made of waste and resource recycling materials, and no three wastes are discharged during the production process. The natural characteristics of cotton, various crop straws and agricultural residual films are utilized to make the product comparable to similar composite materials. No glue is added during the production process, the finished product is formaldehyde-free, and can be used indoors and outdoors, with good effects and a wide range of applications.

[0027] The composite board provided by the present invention can be nailed, drilled, cut, is non-toxic and pollution-free, has low cost, is easy to process, has no scraps and has excellent comprehensive performance. It can be widely used in outdoor garden landscapes, park plank roads, stools and chairs, corridors, flower boxes, pallets and door panels, cabinet panels, furniture packaging and other fields, and is an ideal material to replace solid wood and other composite materials.

[0028] Another aspect of the present invention provides a method for preparing a composite board of thermoplastic recycled plastic and plant straw, which comprises at least the following steps:

[0029] (1) adding thermoplastic recycled plastic, plant straw, compatibilizer, lubricant, antioxidant, ultraviolet absorber, and pigment into a mixer and stirring for 5-15 minutes to obtain a mixture;

[0030] (2) granulating the mixture to obtain composite particles;

[0031] (3) The composite particles are extruded and molded to obtain a composite board.

[0032] As a preferred technical solution, the granulation in step (2) is carried out using a single-screw granulator or a twin-screw granulator.

[0033] Preferably, the melting temperature of the single screw granulator is set to 130-230°C with an increase of 10°C in each temperature zone. The melting temperature of the twin screw granulator is set to 120-220°C with an increase of 10°C in each temperature zone.

[0034] As a preferred technical solution, the extrusion in step (3) is performed using a parallel twin-screw extruder or a conical twin-screw extruder.

[0035] Preferably, the melt temperature of the parallel twin-screw extruder or the conical twin-screw extruder is set to 140-180° C. in increments of 10° C. per temperature zone.

[0036] Preferably, the converging core temperature of the parallel twin-screw extruder or the conical twin-screw extruder is set at 130-150°C.

[0037] Preferably, in the step (4), the temperature of the four zones of the mold for mold shaping is uniformly set to 150-170°C.

[0038] Beneficial Effects

[0039] 1. The present invention provides a composite board of thermoplastic recycled plastic and plant straw. The thermoplastic recycled plastic and plant straw are composited to prepare a board product with excellent performance. It not only solves the problem of soil pollution caused by agricultural residual film, but also avoids the pests and diseases caused by crushing cotton straw and returning it to the field, thereby improving the economic efficiency of cotton straw. It realizes the transformation of waste into treasure, and also opens up a new utilization path for the comprehensive reuse of agricultural residual film and plant straw.

[0040] 2. The present invention prepares thermoplastic recycled plastics by crushing residual film from farmland and performing anhydrous impurity removal treatment and then granulating the resulting film. Combined with plant straw length control and the mass ratio of thermoplastic recycled plastics and plant straw in the system, the prepared composite board has a low water absorption rate and excellent processability, compressive strength and elastic modulus, which can better meet practical application needs.

[0041] 3. The present invention controls the mass ratio of thermoplastic recycled plastics and plant straw to (45-55): (40-50), and controls the addition amount of maleic anhydride, stearic acid, antioxidant and ultraviolet absorber in the coordination system, so that the provided composite board has a compressive strength of more than 28 MPa, an elastic modulus of more than 4000 MPa, and a water absorption rate of less than 1.8%. The board has good molding, no bubbles, a smooth surface and high yield.

[0042] 4. The composite board provided by the present invention is mainly made of waste and resource recycling materials, and no three wastes are discharged during the production process. The natural characteristics of cotton, various crop straws and agricultural residual films are utilized to make the product comparable to similar composite materials. No glue is added during the production process, the finished product is formaldehyde-free, and can be used indoors and outdoors, with good effects and a wide range of applications.

[0043] 5. The composite board provided by the present invention can be nailed, drilled, cut, is non-toxic and pollution-free, has low cost, is easy to process, has no scraps and has excellent comprehensive performance. It can be widely used in outdoor garden landscapes, park plank roads, benches and chairs, pergolas, flower boxes, pallets and door panels, cabinet panels, furniture packaging and other fields. It is an ideal material to replace solid wood and other composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a physical picture of the anhydrous impurity removal device used in the embodiments of the present application. DETAILED DESCRIPTION

[0045] Examples 1-6

[0046] On the one hand, Examples 1-6 of the present invention provide a composite board of thermoplastic recycled plastic and plant straw, and the formula is shown in Table 1 in parts by weight.

[0047] Table 1

[0048]

[0049] The preparation method of the thermoplastic recycled plastic is as follows: recycled waste thermoplastic plastic products are sequentially crushed, impurity removed and granulated.

[0050] The recycled waste thermoplastic plastic products are residual agricultural films.

[0051] The crushing device is a semi-support shaft knife type crushing device.

[0052] The impurity removal device is a dehydration impurity removal device.

[0053] The length of the plant straw is ≤5 cm.

[0054] The plant straw is cotton straw.

[0055] On the other hand, embodiments 1-6 of the present invention provide a method for preparing a composite board of thermoplastic recycled plastic and plant straw, comprising the following steps: (1) adding thermoplastic recycled plastic, plant straw, a compatibilizer, a lubricant, an antioxidant, an ultraviolet absorber, and a pigment into a mixer and stirring and mixing for 5-15 minutes to obtain a mixture;

[0056] (2) granulating the mixture to obtain composite particles;

[0057] (3) The composite particles are extruded and molded to obtain a composite board.

[0058] In the step (2), a twin-screw granulator is used for granulation.

[0059] The melting temperature of the twin-screw granulator is set to 120-220°C in increments of 10°C in each temperature zone.

[0060] In the step (3), a parallel twin-screw extruder is used for extrusion.

[0061] The melting temperature of the parallel twin-screw extruder or the conical twin-screw extruder is set to 140-180° C. in increments of 10° C. in each temperature zone.

[0062] The converging core temperature of the parallel twin-screw extruder or the conical twin-screw extruder was set to 140°C.

[0063] In the step (4), the temperature of the four zones of the mold for mold finalization is uniformly set to 160°C.

[0064] The mold has a four-hole end face of 150mm*25mm and a wall thickness of 5.5mm.

[0065] Performance Testing Methods

[0066] The elastic modulus, compressive strength, formaldehyde content and water absorption of the composite board provided in the embodiment were tested, and the test results are shown in Table 2; the appearance of the composite board during processing and the obtained composite board were recorded, and the results are shown in Table 2.

[0067] (1) Elastic modulus: Reference standard: GB / T29418-2012 Physical and mechanical properties test of wood-plastic composite materials.

[0068] (2) Compressive strength: Reference standard: GB / T24508-2020.

[0069] (3) Formaldehyde content: Reference standard: HJ2540-201 Technical requirements for environmental labeling of wood plastic products

[0070] (4) Water absorption rate: Reference standard: GB / T24508-2020 wood plastic flooring.

[0071] Table 2

[0072]

[0073]

[0074] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A thermoplastic recycled plastic and plant straw composite board, characterized in that: The raw materials include at least 20-60 parts of thermoplastic recycled plastic, 30-70 parts of plant straw, 1-5 parts of compatibilizer, 1-5 parts of lubricant, 0.1-1 parts of antioxidant, 0.1-1 parts of ultraviolet absorber and 0-3 parts of pigment, in parts by weight.

2. The thermoplastic recycled plastic and plant straw composite board according to claim 1, characterized in that: The preparation method of the thermoplastic recycled plastic is as follows: recycled waste thermoplastic plastic products are sequentially crushed, impurity removed and granulated.

3. The thermoplastic recycled plastic and plant straw composite board according to claim 2, characterized in that: The length of the plant straw is ≤10 cm.

4. The thermoplastic recycled plastic and plant straw composite board according to claim 3, characterized in that: The mass ratio of the thermoplastic recycled plastic to the plant straw is (45-55):(40-50).

5. The thermoplastic recycled plastic and plant straw composite board according to claim 4, characterized in that: The compatibilizer is selected from at least one of epoxy type, carboxylic acid type and anhydride type, and the added amount of the compatibilizer accounts for more than 4.5% of the mass of the plant straw.

6. The thermoplastic recycled plastic and plant straw composite board according to claim 5, characterized in that: The lubricant is selected from at least one of amides, stearic acid and its derivatives, and the added amount of the lubricant accounts for less than 4.8% of the mass of the thermoplastic recycled plastic.

7. The thermoplastic recycled plastic and plant straw composite board according to claim 6, characterized in that: The antioxidant is selected from at least one of hindered phenol antioxidants, phosphite antioxidants and hindered amine antioxidants.

8. The thermoplastic recycled plastic and plant straw composite board according to claim 6, characterized in that: The ultraviolet absorber is selected from at least one of a benzotriazole ultraviolet absorber and a benzophenone ultraviolet absorber.

9. The thermoplastic recycled plastic and plant straw composite board according to claim 8, characterized in that: The mass ratio of the antioxidant to the ultraviolet absorber is 1:(1-2).

10. A method for preparing a composite board of thermoplastic recycled plastic and plant straw according to any one of claims 1 to 9, characterized in that: At least the following steps are included: (1) adding thermoplastic recycled plastic, plant straw, compatibilizer, lubricant, antioxidant, ultraviolet absorber, and pigment into a mixer and stirring for 5-15 minutes to obtain a mixture; (2) granulating the mixture to obtain composite particles; (3) The composite particles are extruded and molded to obtain a composite board.

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