A bio-based polyurethane foam mulch composition and methods of making and using the same

Abstract

The present application relates to a kind of bio-based polyurethane foam mulch compositions and its preparation method and application, and the mulch composition includes component A and component B, the component A includes soybean oil polyol, nanocellulose hydrogel, foam stabilizer and catalyst, catalyst is organic tin catalyst and / or amine catalyst;The component B is isocyanate.Two components A and B are mixed, atomized and sprayed, and the foam film with good spraying performance and physical performance is obtained.The present application not only solves the problem of excessive dependence on petroleum-based polyether polyol in the field of polyurethane foam, but also does not need to introduce additional foaming agent.The mulch not only has the heat preservation, moisture retention function of traditional mulch, but also has biodegradable performance, which is conducive to reducing soil pollution, and meets the requirements of environmental protection and sustainable development.The method is simple and easy to operate, suitable for large-scale production and popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane technology, specifically relating to a soybean oil-based polyurethane foam mulch film, its preparation method, and its application. Background Technology

[0002] Mulching technology, as a low-cost and practical planting technique, is widely used in agricultural planting. This technology can mitigate the impact of rain on crops, effectively reduce soil moisture evaporation, maintain suitable soil temperature and humidity, promote crop water absorption and growth, and significantly increase crop yield. Agricultural mulch film is the key material in this technology. In practical use, agricultural mulch film is affected by wind erosion, rainwater erosion, and soil cracking; therefore, it requires materials with high mechanical strength, toughness, and corrosion resistance.

[0003] Polyurethane materials, due to their designable molecular structure, excellent corrosion resistance, and mechanical properties, have promising applications in agricultural mulch films. However, like polyethylene, traditional polyurethane materials are petroleum-based, with non-renewable raw materials and no biodegradability in natural environments, putting pressure on environmental and resource sustainability. With the increasing depletion of petroleum resources and the growing national emphasis on environmental protection, research on preparing bio-based polyurethane foam materials using natural, renewable biomass raw materials to fully or partially replace fossil resources has received widespread attention.

[0004] Soybean oil is an abundant and renewable resource. Its molecules contain a triglyceride structure, composed of glycerol and three fatty acid chains. Soybean oil polyols can be prepared by epoxidizing soybean oil with hydroxylation. The resulting polyols have high hydroxyl values, as well as relatively low molecular weight and viscosity. Applying them to the preparation of polyurethane foam materials is of great significance for conserving petroleum resources and protecting the ecological environment.

[0005] Despite the environmental advantages of bio-based polyurethane foam, its application in the field of mulch films is still limited by the physical properties and processing methods of existing products. Existing bio-based polyurethane foams are often difficult to promote on a large scale due to insufficient mechanical strength, processing difficulties, or excessive costs. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a method for preparing a soybean oil-based polyurethane foam mulch film reinforced with nanocellulose hydrogel.

[0007] The technical solution of this invention is as follows:

[0008] A bio-based polyurethane foam mulch film composition includes component A and component B, wherein component A includes soybean oil polyol, nanocellulose hydrogel, foam stabilizer and catalyst, the catalyst being an organotin catalyst and / or an amine catalyst; and component B is an isocyanate.

[0009] Preferably, by weight, the composition comprises 40-60 parts soybean oil polyol, 0.5-10 parts nanocellulose hydrogel, 0.1-2 parts foaming agent, 0.1-1 parts catalyst, and 35-55 parts isocyanate.

[0010] Preferably, by weight, the composition comprises 50±5 parts soybean oil polyol, 1-5 parts nanocellulose hydrogel, 1±0.5 parts foaming agent, 0.5±0.2 parts catalyst, and 40-50 parts isocyanate.

[0011] Preferably, the foaming agent is dimethyl silicone oil, the isocyanate is toluene diisocyanate; the organotin catalyst is any one or more of stannous octoate or dibutyltin dilaurate; and the amine catalyst is any one or more of triethylenediamine, bis(2-dimethylaminoethyl) ether or triethanolamine.

[0012] Preferably, the hydroxyl value of the soybean oil polyol is 326±20mg KOH / g.

[0013] Preferably, the nanocellulose hydrogel is a nanocellulose fiber hydrogel and / or a nanocellulose crystal hydrogel.

[0014] Preferably, the diameter of the nanocellulose fiber hydrogel is 3-5 nm and the length is 500-1000 nm, and the diameter of the nanocellulose crystal hydrogel is 3-5 nm and the length is 200-500 nm.

[0015] Preferably, the solid content of the nanocellulose hydrogel is 2.0 ± 1.5 wt%.

[0016] The application of the composition involves mixing components A and B and then atomizing and spraying the mixture through a foam nozzle to generate a polyurethane foam mulch film. The specific steps include:

[0017] (1) Mix component A thoroughly and add it to tube A of the pneumatic glue gun;

[0018] (2) Add component B into tube B of the pneumatic glue gun;

[0019] (3) Turn on the air compressor switch and adjust the spraying speed. The two components of liquid in pipes A and B are mixed and then atomized and sprayed out through the foam head to instantly generate polyurethane foam mulch.

[0020] The bio-based polyurethane foam mulch film can be widely used in agricultural planting.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The polyurethane foam mulch of the present invention introduces nanocellulose hydrogel, which not only enhances the mechanical properties of the foam, but also allows the water in the nanocellulose hydrogel to be used for foaming without the need for additional foaming agent. Furthermore, the nanocellulose enhances the mechanical properties of the foam, making it green, environmentally friendly, simple and easy to implement.

[0023] (2) The present invention uses soybean oil-based polyol to replace petroleum-based polyether polyol, which is green and environmentally friendly. The mulch film can be quickly formed by spraying equipment to form a mulch film with excellent mechanical properties and environmentally friendly characteristics. It is easy to process and has low cost, which can greatly improve the application efficiency and environmental adaptability of polyurethane foam mulch film.

[0024] (3) The polyurethane foam mulch of the present invention not only has the heat preservation and moisture retention functions of traditional mulch, but also has biodegradable properties, which helps reduce soil pollution and meets the requirements of environmental protection and sustainable development. It also exhibits excellent mechanical properties, and its toughness can effectively cope with the mulch damage caused by soil cracks, ensuring stability under complex soil conditions. At the same time, the mulch has high strength and excellent hydrophobicity, and can maintain its functionality even when subjected to erosion by natural environmental factors such as rainwater. Compared with other types of mulch, it exhibits more reliable performance. Attached Figure Description

[0025] Figure 1 These are comparison photos before and after the application of foam mulch film.

[0026] Figure 2 The images show the morphology of polyurethane foam prepared in different embodiments (Examples 3 and 4, Comparative Examples 1 and 2) after standing for 30 days. Detailed Implementation

[0027] Unless otherwise specified in the embodiments and comparative examples of this invention, the conditions shall be performed under conventional conditions or conditions recommended by the manufacturer.

[0028] All raw materials and reagents used without specifying the manufacturer were commercially available products. The two types of nanocellulose hydrogels used in the examples were purchased from Henan Kegao Radiation Chemical Technology Co., Ltd., specifically nanocellulose fiber hydrogel and nanocellulose crystal hydrogel (concentration 2wt%).

[0029] Example 1

[0030] A sprayable bio-based polyurethane foam mulch film composition comprises two components, A and B. Component A includes: 50 parts soybean oil polyol, 5 parts nanocellulose fiber hydrogel, 1 part dimethyl silicone oil, and 0.5 parts dibutyltin dilaurate; Component B includes: 43.5 parts toluene diisocyanate.

[0031] After mixing component A thoroughly, add it to pipe A of the pneumatic glue gun. Add components B to pipe B of the pneumatic glue gun. When using, push the liquids from both pipes into the mixing tube simultaneously, and spray them out through the atomizing head to form a film instantly.

[0032] Example 2

[0033] A sprayable bio-based polyurethane foam mulch film composition comprises two components, A and B. Component A includes: 50 parts soybean oil polyol, 5 parts nanocellulose crystal hydrogel, 1 part dimethyl silicone oil, and 0.5 parts dibutyltin dilaurate; Component B includes: 43.5 parts toluene diisocyanate.

[0034] After mixing component A thoroughly, add it to pipe A of the pneumatic glue gun. Add components B to pipe B of the pneumatic glue gun. When using, push the liquids from both pipes into the mixing tube simultaneously, and spray them out through the atomizing head to form a film instantly.

[0035] Example 3

[0036] A sprayable bio-based polyurethane foam mulch film composition comprises two components, A and B. Component A includes: 52 parts soybean oil polyol, 3 parts nanocellulose fiber hydrogel, 1 part dimethyl silicone oil, and 0.5 parts triethylenediamine; Component B includes: 43.5 parts toluene diisocyanate.

[0037] After mixing component A thoroughly, add it to pipe A of the pneumatic glue gun. Add components B to pipe B of the pneumatic glue gun. When using, push the liquids from both pipes into the mixing tube simultaneously, and spray them out through the atomizing head to form a film instantly.

[0038] Example 4

[0039] A sprayable bio-based polyurethane foam mulch film composition comprises two components, A and B. Component A includes: 52 parts soybean oil polyol, 3 parts nanocellulose crystal hydrogel, 1 part dimethyl silicone oil, and 0.5 parts triethylenediamine; Component B includes: 43.5 parts toluene diisocyanate.

[0040] After mixing component A thoroughly, add it to pipe A of the pneumatic glue gun. Add components B to pipe B of the pneumatic glue gun. When using, push the liquids from both pipes into the mixing tube simultaneously, and spray them out through the atomizing head to form a film instantly.

[0041] Example 5

[0042] A sprayable bio-based polyurethane foam mulch film composition comprises two components, A and B. Component A includes: 54 parts soybean oil polyol, 1 part nanocellulose fiber hydrogel, 1 part dimethyl silicone oil, and 0.5 parts stannous octoate; Component B includes: 43.5 parts toluene diisocyanate.

[0043] After mixing component A thoroughly, add it to pipe A of the pneumatic glue gun. Add components B to pipe B of the pneumatic glue gun. When using, push the liquids from both pipes into the mixing tube simultaneously, and spray them out through the atomizing head to form a film instantly.

[0044] Comparative Example 1

[0045] A sprayable bio-based polyurethane foam mulch film composition comprises two components, A and B. Component A includes: 54 parts soybean oil polyol, 1 part deionized water, 1 part dimethyl silicone oil, and 0.5 parts stannous octoate; Component B includes: 43.5 parts toluene diisocyanate.

[0046] After mixing component A thoroughly, add it to pipe A of the pneumatic glue gun. Add components B to pipe B of the pneumatic glue gun. When using, push the liquids from both pipes into the mixing tube simultaneously, and spray them out through the atomizing head to form a film instantly.

[0047] Comparative Example 2

[0048] A sprayable bio-based polyurethane foam mulch film composition comprises two components, A and B. Component A includes: 52 parts soybean oil polyol, 3 parts microcrystalline cellulose hydrogel, 1 part dimethyl silicone oil, and 0.5 parts stannous octoate; Component B includes: 43.5 parts toluene diisocyanate.

[0049] After mixing component A thoroughly, add it to pipe A of the pneumatic glue gun. Add components B to pipe B of the pneumatic glue gun. When using, push the liquids from both pipes into the mixing tube simultaneously, and spray them out through the atomizing head to form a film instantly.

[0050] Thermal insulation performance test: A certain amount of polyurethane foam was sprayed evenly on the leveled soil surface, and the temperature at 10cm below the ground was tested within two weeks. The average temperature increase of the soil after the mulch film was covered was also recorded.

[0051] Soil water retention capacity test: Foam mulch was evenly sprayed onto the soil surface, and the change in soil moisture content was measured over two weeks. Soil samples were taken from 10 cm below the soil surface and dried to constant weight in an oven at 105℃. The mass of the dried soil was recorded as G1. Water of mass G2 was added to the soil. After the water evaporated, the mass of the dried soil was recorded as G3. The soil water retention rate was calculated using the following formula.

[0052] W(%)=(G3-G1) / G3×100

[0053] Tear strength test: The tear strength of the sample is tested in accordance with GB / T 10808-2006 to characterize the ability of foam mulch film to resist damage from external forces.

[0054] Toughness test: The toughness of polyurethane foam materials is characterized by elongation at break, and the test is conducted in accordance with ABNT NBR 8515-2020.

[0055] Table 1. Performance Comparison of Polyurethane Foam Mulch Films

[0056]

[0057] As shown in Table 1, compared with Comparative Examples 1 and 2, the addition of nanocellulose fiber gel and nanocellulose crystal gel can improve the overall performance of polyurethane foam mulch. The tear strength of the polyurethane foam mulch is significantly improved because nanocellulose has a high modulus, good abrasion resistance, and a reinforcing effect. Comparing Examples 3 and 4, it can be seen that the polyurethane foam mulch with added nanocellulose fibers has a higher elongation at break, which is closely related to the large aspect ratio of nanocellulose fibers. Compared with Comparative Examples 1 and 2, the increase in soil temperature in Examples 1-5 may be related to the cross-linked foam network formed by nanocellulose, soybean oil polyol, and diisocyanate. With the increase of nanocellulose content (Examples 1, 3, and 5), the soil water retention rate increases because the surface of nanocellulose contains a large number of hydroxyl groups, which are highly hydrophilic. In addition, the water retention rate of Comparative Example 2 is low, mainly because its size is large and its content is low.

[0058] Using Examples 3, 4, Comparative Example 1, and Comparative Example 2 as examples, the stability of the polyurethane foam mulch was further tested. Potted plants with the polyurethane foam mulch evenly sprayed were placed near a ventilated window, and the rupture of the polyurethane foam was observed at regular intervals. The following are images of the foam mulch taken 30 days later. Figure 2 As shown, the foams in Comparative Examples 1 and 2 partially collapsed, but did not completely disappear, instead exhibiting a polyurethane film morphology, which still had a certain promoting effect on the soil's heat and water retention performance. This is because polyurethane foam is a solid foam, and the cells are formed by cross-linking of polyols and isocyanates, which has a strong scaffold function and is not easy to collapse, thus it can exist stably on the soil surface. Compared with Comparative Examples 1 and 2, the foam films in Examples 3 and 4 were more uniform and dense, and there was no significant difference in the foam after 30 days, indicating that both nanocellulose fibers and nanocellulose crystals have a promoting effect on the stability of the foam. Compared with Comparative Examples 1 and 2, the addition of nanocellulose can improve the stability of polyurethane foam.

[0059] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bio-based polyurethane foam mulch film composition, characterized in that, The product comprises component A and component B. Component A includes soybean oil polyol, nanocellulose hydrogel, foam stabilizer, and catalyst, wherein the catalyst is an organotin catalyst and / or an amine catalyst; and component B is an isocyanate. The hydroxyl value of the soybean oil polyol is 326±20 mg KOH / g; By weight, the composition includes 40-60 parts soybean oil polyol, 0.5-10 parts nanocellulose hydrogel, 0.1-2 parts foaming agent, 0.1-1 parts catalyst, and 35-55 parts isocyanate. The solid content of the nanocellulose hydrogel is 2.0±1.5wt%; the composition utilizes the water in the nanocellulose hydrogel for foaming, without introducing additional foaming agent, to obtain a bio-based polyurethane foam mulch film.

2. The composition according to claim 1, characterized in that, By weight, the composition includes 50±5 parts soybean oil polyol, 1-5 parts nanocellulose hydrogel, 1±0.5 parts foaming agent, 0.5±0.2 parts catalyst, and 40-50 parts isocyanate.

3. The composition according to claim 1, characterized in that, The foaming agent is dimethyl silicone oil, and the isocyanate is toluene diisocyanate; the organotin catalyst is any one or more of stannous octoate or dibutyltin dilaurate; the amine catalyst is any one or more of triethylenediamine, bis(2-dimethylaminoethyl) ether or triethanolamine.

4. The composition according to any one of claims 1 to 3, characterized in that, The nanocellulose hydrogel is a nanocellulose fiber hydrogel and / or a nanocellulose crystal hydrogel.

5. The composition according to claim 4, characterized in that, The nanocellulose fiber hydrogel has a diameter of 3-5 nm and a length of 500-1000 nm, while the nanocellulose crystal hydrogel has a diameter of 3-5 nm and a length of 200-500 nm.

6. The use of the composition according to any one of claims 1 to 5, characterized in that, Components A and B are mixed and then atomized and sprayed through a foam nozzle to generate a polyurethane foam mulch film.

7. The application according to claim 6, characterized in that, Includes the following steps: (1) Mix component A thoroughly and add it to tube A of the pneumatic glue gun; (2) Add component B into tube B of the pneumatic glue gun; (3) Turn on the air compressor switch and adjust the spraying speed. The two components of liquid in pipes A and B are mixed and then atomized and sprayed out through the foam head to generate polyurethane foam mulch.

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