Preparation method of porous noise-reducing organic surface cover

Abstract

The present invention discloses a method for preparing a porous, noise-reducing organic ground cover. The method is specifically implemented in the following steps: Step 1: Obtain branches and cut them to obtain cuttings or pellets; Step 2: Naturally air-dry the cuttings or pellets obtained in Step 1 to form a common organic ground cover; Step 3: Prepare a porogen; Step 4: Allow the cuttings obtained in Step 2 to fully absorb the porogen prepared in Step 3, and then subject the substrate to crawler-type microwave drying to obtain the porous, noise-reducing organic ground cover. The method utilizes tracheids to absorb the porogen to form gas-induced pores, forming a porous surface structure that effectively reduces noise.

Description

Technical Field

[0001] The invention belongs to the technical field of ground cover, and in particular relates to a method for preparing a porous noise-reducing organic ground cover. Background Art

[0002] Ordinary organic mulch uses urban garden prunings, farmland straw and other organic waste as the main base material. After removing leaves and impurities, it is squeezed, cut, dried, and colored to form different colors and patterns. It has the ability to regulate soil temperature; reduce soil salinity; effectively control weeds; absorb and decompose pollution; beautify and green the environment; reduce soil erosion and compaction; and reduce green space maintenance costs. It can be laid on bare surfaces in parks, green belts, urban gardens, landscape woodlands, GMP standard enterprise factories, and construction excavation sites to form a cover.

[0003] Urban garden noise destroys the tranquil beauty of gardens, affects animal habitats, and even causes health problems for humans, including hearing, cardiovascular and cerebrovascular, and nervous systems. High-frequency noise is sharp and has a very short wavelength. It can decay rapidly with increasing distance or encountering obstacles. Low-frequency noise (20-500Hz) does not have a high decibel level, but it decays very slowly and has a long wavelength. Therefore, it can penetrate the human ear from a long distance. Low-frequency noise has a more long-term impact on human health than general noise and has long-term potential effects. The porous sound-absorbing material's pore sound absorption mechanism is that the material has a large number of tiny pores. Sound waves can penetrate deep into the material along these pores, rubbing against the material to achieve Helmholtz resonance, sound energy heat conversion, and other phenomena to achieve sound absorption and attenuation. However, materials with uneven surfaces basically have no sound absorption ability, and in fact, materials with porous surfaces are good sound-absorbing materials.

[0004] The tracheids and tracheids in the xylem of garden prunings are thick-walled, elongated dead cells with capillary patterns of rings, spirals, ladders, reticulations and holes on the walls. Because tracheids are single cells with no perforations on the end walls, the number of tracheid openings on the xylem surface is limited, which also results in the inability of ordinary organic coverings to absorb and reduce noise. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a porous noise-reducing organic ground cover, so as to solve the problem that existing ground covers and garden covers cannot effectively reduce noise.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: a method for preparing a porous noise-reducing organic surface cover, which is specifically implemented according to the following steps:

[0007] Step 1: Obtain branches and cut them into cutting pieces or cutting particles;

[0008] Step 2, naturally drying the cutting pieces or cutting particles obtained in step 1 to form a common organic surface cover;

[0009] Step 3, preparing a porogen;

[0010] Step 4: allowing the cutting material substrate obtained in step 2 to fully absorb the porogen prepared in step 3, and then subjecting it to crawler-type microwave drying to obtain a porous noise-reducing organic surface cover.

[0011] As a preferred technical solution of the present invention, in step 1, the branches are the products of garden pruning waste after the fallen fruits, flowers, petioles and leaves are removed.

[0012] As a preferred technical solution of the present invention, the width and thickness of the cutting piece or cutting particle are 0.5 cm to 3 cm, and the length is 1 cm to 8 cm.

[0013] As a preferred technical solution of the present invention, in step 2, the natural drying temperature is 18°C-35°C.

[0014] As a preferred technical solution of the present invention, in step 3, the porogen is composed of 3%-15% ammonium bicarbonate, 2%-6% ammonium chloride and the balance water in terms of mass percentage.

[0015] As a preferred technical solution of the present invention, in step 4, the moisture content of the cutting material substrate is maintained at 50%-80% after the cutting material substrate fully absorbs the porogen prepared in step 3.

[0016] As a preferred technical solution of the present invention, in step 4, the power of the crawler-type microwave drying is 100 kW-140 kW, and the moisture content after crawler-type microwave drying is 1.5%-2%.

[0017] The beneficial effects of the present invention are: a preparation method of a porous noise-reducing organic surface cover of the present invention adopts a method in which vessels and tracheids absorb porogens in combination with microwaves to form a "micro-explosion", thereby forming a microporous structure on the vessel wall. Compared with ethanol-water as a reference porogen and compared with ordinary surface covers, the porous noise-reducing organic surface cover formed by the present invention has a more obvious porous structure, effectively creating holes with a diameter of 1-10 microns on the vessel wall of the xylem of ordinary organic covers, and can form an effective sound-absorbing material for medium and low frequency noise of 20-1200Hz. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a comparison of electron microscope microscopic characterizations of the hydrophilic porous noise-reducing organic surface cover prepared by the method of the present invention;

[0019] Figure 2This is a noise reduction comparison chart of the hydrophilic porous noise-reducing organic surface cover prepared by the method of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] The present invention is further described below by way of examples, but is not limited to the following embodiments.

[0022] Example 1

[0023] The method for preparing a porous noise-reducing organic ground cover of the present invention is specifically implemented according to the following steps:

[0024] Step 1: After removing fallen fruits, flowers, petioles and leaves from garden pruning waste, branches are obtained, and the branches are cut into cutting pieces or cutting particles with a width and thickness of 3 cm and a length of 8 cm;

[0025] Step 2: drying the cuttings or chips obtained in step 1 naturally at 18° C. to form a common organic ground cover;

[0026] Step 3, preparing a porogen; the porogen is composed of 3% ammonium bicarbonate, 2% ammonium chloride and 95% water in percentage by mass;

[0027] Step 4: After the cutting material substrate obtained in step 2 fully absorbs the porogen prepared in step 3, the moisture content is maintained at 50%, and then it is subjected to 100 kW crawler microwave drying to a moisture content of 1.5%, thereby obtaining a porous noise-reducing organic surface cover.

[0028] Example 2

[0029] The method for preparing a porous noise-reducing organic ground cover of the present invention is specifically implemented according to the following steps:

[0030] Step 1: After removing fallen fruits, flowers, petioles and leaves from garden pruning waste, branches are obtained, and the branches are cut into cutting pieces or cutting particles with a width and thickness of 0.5 cm and a length of 1 cm;

[0031] Step 2: drying the cuttings or chips obtained in step 1 naturally at 35° C. to form a common organic ground cover;

[0032] Step 3, preparing a porogen; the porogen is composed of 15% ammonium bicarbonate, 6% ammonium chloride and 79% water in percentage by mass;

[0033] Step 4: After the cutting material base material obtained in step 2 fully absorbs the porogen prepared in step 3, the moisture content is maintained at 80%, and then it is subjected to 140kw crawler microwave drying to a moisture content of 2%, thereby obtaining a porous noise-reducing organic surface cover.

[0034] Example 3

[0035] The method for preparing a porous noise-reducing organic ground cover of the present invention is specifically implemented according to the following steps:

[0036] Step 1: After removing fallen fruits, flowers, petioles and leaves from garden pruning waste, branches are obtained, and the branches are cut into cutting pieces or cutting particles with a width and thickness of 2 cm and a length of 4 cm;

[0037] Step 2: drying the cuttings or chips obtained in step 1 naturally at 26° C. to form a common organic ground cover;

[0038] Step 3, preparing a porogen; the porogen is composed of 9% ammonium bicarbonate, 4% ammonium chloride and 65% water in percentage by mass;

[0039] Step 4: After the cutting material substrate obtained in step 2 fully absorbs the porogen prepared in step 3, the moisture content is maintained at 65%, and then it is subjected to 120kw crawler microwave drying to a moisture content of 1.8%, thereby obtaining a porous noise-reducing organic surface cover.

[0040] Microwave-induced porogenesis is a common technique for forming porous materials. However, for wooden substrates, the tracheids have already lost water, and the effect of microwave-induced porogenesis using ordinary solvents is limited. The present invention uses a gas-explosion porogen to infiltrate the tracheids and tracheids. After microwave treatment, the porogen completely evaporates into gas, and a large amount of gas forms "micro-explosions" in the tracheids, resulting in micropores on the surface of the cutting pieces or particles, forming a porous covering on the tracheid walls.

[0041] The key technology of the present invention is to use extruded cutting pieces or cutting particles of landscaping prunings as the base material of the organic cover, embed tiny gas-producing droplets into the xylem vessels of the base material, and form "micro-gas explosions" under the action of microwaves to produce tracheid micropores, forming an organic surface cover with a porous surface of the vessel wall and an interlaced and connected sound-absorbing structure, which achieves the effect of absorbing low-frequency noise after being laid on the surface.

[0042] The hydrophilic mechanism of the present invention is to use a low-element complex alcohol solution to increase the extension degree of the hydroxyl groups of the covering lignin, thereby promoting the ammonium salt porogen to penetrate into the vessels and fill the tracheids.

[0043] Since the decomposition temperature of ammonium bicarbonate solution ranges from 36°C to 60°C, the process is relatively long and insufficient to produce a "gas explosion" effect. The pore-forming principle of the present invention is that ammonium chloride decomposes to produce HCL under the action of microwaves, which further accelerates the rapid decomposition of ammonium bicarbonate to form a "micro-gas explosion". CO2 will not slowly overflow due to dissolution. Through experiments, the appropriate ammonium salt solution ratio was screened to ensure that the acid and base ammonium salts react quickly and completely under the action of microwaves.

[0044] NH4Cl→NH3↑+HCl↑

[0045] NH4HCO3→NH3↑+CO2↑+H2O

[0046] NH4HCO3+HCl→NH4Cl+H2O+CO2↑

[0047] Table 1 Comparison of 900Hz sound absorption coefficient α of different covers

[0048]

[0049]

[0050] From the data results in Table 1, it can be seen that the organic soil cover of the present invention can reach the range of sound absorbing material (α>0.2) and ideal sound absorbing material (α>0.5) as the laying thickness increases.

[0051] Combine Figure 1 , wherein a is a characterization diagram of the outer wall of the ordinary organic covering conduit, b is a characterization diagram of the gas explosion effect of the covering conduit wall produced by using 5% ethanol as a porogen, and c is a characterization diagram of the gas explosion effect of the conduit wall of the porous noise-reducing organic covering of the present invention (obtained in Example 1).

[0052] Combine Figure 2 , Figure 2 The simulated environment temperature is 19℃, relative humidity is 50%, atmospheric pressure is 101325Pa, and air density is 1.2061kg / m 3 The sound absorption coefficient α of the impedance large pipe was measured for low- and medium-frequency noise discernible to the human ear from 20 Hz to 1200 Hz, with a sound velocity of 342.651 m / s, characteristic air impedance of 413.273 Pa·s / m, and a covering thickness of 1 cm. It can be seen that the porous noise-reducing organic surface covering of the present invention (obtained in Example 1) has a higher sound absorption capacity than ordinary organic coverings, with a sound absorption coefficient exceeding 0.2 for frequencies from low 400 Hz to mid-frequency 1200 Hz.

Claims

1. A method for preparing a porous noise-reducing organic surface cover, characterized in that: Please follow the steps below to implement it: Step 1: Obtain branches and cut them into cutting pieces or cutting particles; Step 2, naturally drying the cutting pieces or cutting particles obtained in step 1 to form a common organic surface cover; Step 3, preparing a porogen; Step 4: allowing the cutting pieces or cutting particles obtained in step 2 to fully absorb the porogen prepared in step 3, and then subjecting them to crawler-type microwave drying to obtain a porous noise-reducing organic surface cover.

2. The method for preparing the porous noise-reducing organic ground cover according to claim 1, characterized in that: In step 1, the branches are the products of garden pruning waste after the fallen fruits, flowers, petioles and leaves are removed.

3. The method for preparing the porous noise-reducing organic ground cover according to claim 2, characterized in that: In step 1, the width and thickness of the cutting piece or cutting particle are 0.5 cm to 3 cm, and the length is 1 cm to 8 cm.

4. The method for preparing the porous noise-reducing organic ground cover according to claim 1, characterized in that: In step 2, the natural drying temperature is 18° C.-35° C.

5. The method for preparing the porous noise-reducing organic ground cover according to claim 3, characterized in that: In step 3, the porogen is composed of 3%-15% ammonium bicarbonate, 2%-6% ammonium chloride and the balance water in terms of mass percentage.

6. The method for preparing the porous noise-reducing organic ground cover according to claim 4, characterized in that: In step 4, the moisture content of the cutting material substrate is maintained at 50%-80% after the porogen prepared in step 4 is fully absorbed by the cutting material substrate.

7. The method for preparing the porous noise-reducing organic ground cover according to claim 5, characterized in that: In step 5, the power of the crawler-type microwave drying is 100 kW to 140 kW, and the moisture content after crawler-type microwave drying is 1.5% to 2%.

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