Bio-based polyurethane foam mulching film composition as well as preparation method and application thereof

Abstract

The invention relates to a bio-based polyurethane foam mulching film composition and a preparation method and application thereof.The mulching film composition comprises a component A and a component B. The component A comprises soybean oil polyol, nano cellulose hydrogel, a foam stabilizer and a catalyst, and the catalyst is an organic tin catalyst and / or an amine catalyst; and the component B is isocyanate. The component A and the component B are mixed, atomized and sprayed out, and the foam film with good spraying performance and physical performance is obtained. The method 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 additionally introduce a foaming agent. The mulching film not only has heat preservation and moisture preservation functions of a traditional mulching film, but also has biodegradability, is beneficial to reduction of soil pollution, and meets the requirements of environmental protection and sustainable development. The method is simple and feasible, and is suitable for large-scale production, popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane, and in particular relates to a soybean oil-based polyurethane foam ground film and a preparation method and application thereof. Background Art

[0002] As a low-cost and practical planting technology, mulching technology is widely used in the field of agricultural planting. This technology can reduce the impact of rain on crops, effectively reduce the evaporation of water in the soil, keep the soil at a suitable temperature and humidity, promote the absorption of water and growth and development of crops, and significantly increase crop yields. Among them, agricultural mulch is the key material of mulching technology. In actual use, agricultural mulch will be affected by wind and sand, rain erosion, and soil cracking. Therefore, agricultural mulch materials are required to have high mechanical strength, toughness and corrosion resistance.

[0003] Polyurethane materials have good application prospects in the field of agricultural mulch films due to their designable molecular structure, excellent corrosion resistance and mechanical properties. However, traditional polyurethane materials, like polyethylene materials, are petroleum-based materials, the raw materials are non-renewable, and they are not degradable in the natural environment, which puts pressure on the sustainable development of the environment and resources. With the increasing depletion of oil resources and the country's increased efforts in environmental protection, research on the use of natural renewable biomass raw materials to fully or partially replace fossil resources to prepare bio-based polyurethane foam materials has received widespread attention.

[0004] Soybean oil is abundant and renewable, and contains a triglyceride structure in its molecule, which is composed of glycerol and three fatty acid chains. Soybean oil polyols can be prepared by epoxidation of soybean oil. The prepared polyols have a high hydroxyl value, and low relative molecular mass and viscosity. Using them to prepare polyurethane foam materials is of great significance to saving petroleum resources and protecting the ecological environment.

[0005] Although bio-based polyurethane foam has environmental advantages, its application in the field of ground film is still limited by the physical properties and processing methods of existing products. Existing bio-based polyurethane foam is often difficult to promote on a large scale due to insufficient mechanical strength, difficult processing or high cost. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a soybean oil-based polyurethane foam mulch film reinforced with nanocellulose hydrogel.

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

[0008] A bio-based polyurethane foam ground film composition comprises component A and component B, wherein component A comprises soybean oil polyol, nanocellulose hydrogel, a foam leveler and a catalyst, wherein the catalyst is an organic tin catalyst and / or an amine catalyst; and component B is isocyanate.

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

[0010] Preferably, in parts by weight, the soybean oil polyol is 50±5 parts, the nanocellulose hydrogel is 1-5 parts, the foam leveling agent is 1±0.5 parts, the catalyst is 0.5±0.2 parts, and the isocyanate is 40-50 parts.

[0011] Preferably, the foam leveling agent is dimethyl silicone oil, 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.

[0012] Preferably, the soybean oil polyol has a hydroxyl value of 326±20 mg 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±1.5wt%.

[0016] The application of the composition comprises mixing components A and B and spraying them through a foam nozzle to form a polyurethane foam ground film, which specifically comprises the following steps:

[0017] (1) Mix component A evenly and add it into tube A of a pneumatic glue gun;

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

[0019] (3) Turn on the air compressor switch and adjust the spraying speed. The two components of liquid in tubes A and B are mixed and sprayed out through the foam head, and a polyurethane foam film is instantly generated.

[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 film of the present invention introduces nanocellulose hydrogel, which not only enhances the mechanical properties of the foam, but also can utilize the water in the nanocellulose hydrogel for foaming without the need to introduce an additional foaming agent. The nanocellulose enhances the mechanical properties of the foam, is green, environmentally friendly, simple and easy to operate.

[0023] (2) The present invention adopts 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 the polyurethane foam mulch film.

[0024] (3) The polyurethane foam mulch film of the present invention not only has the heat preservation and moisture retention functions of traditional mulch films, but also has biodegradability, which is conducive to reducing soil pollution, meets the requirements of environmental protection and sustainable development, and also exhibits excellent mechanical properties. Its toughness can effectively deal with the problem of mulch damage caused by soil cracks, ensuring stability under complex soil conditions. At the same time, the mulch film has high strength and excellent hydrophobicity. Even if it is eroded by natural environmental factors such as rain, its functionality can remain unaffected. Compared with other types of mulch films, it exhibits more reliable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a comparison picture before and after spraying the foam mulch.

[0026] Figure 2 The morphology of the polyurethane foams prepared in different embodiments (Examples 3 and 4, Comparative Examples 1 and 2) after standing for 30 days. DETAILED DESCRIPTION

[0027] If no specific conditions are specified in the examples and comparative examples of the present invention, the reactions were carried out according to conventional conditions or conditions recommended by the manufacturer.

[0028] All raw materials and reagents used without indicating the manufacturer are conventional products that can be purchased from the market. The two 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 of 2 wt%).

[0029] Example 1

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

[0031] After mixing component A evenly, add it to pipe A of the pneumatic glue gun, and add component B to pipe B of the pneumatic glue gun. When using, push the liquids in both pipes into the mixing tube at the same time, and spray them out through the atomizing head to form a film instantly.

[0032] Example 2

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

[0034] After mixing component A evenly, add it to pipe A of the pneumatic glue gun, and add component B to pipe B of the pneumatic glue gun. When using, push the liquids in both pipes into the mixing tube at the same time, and spray them out through the atomizing head to form a film instantly.

[0035] Example 3

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

[0037] After mixing component A evenly, add it to pipe A of the pneumatic glue gun, and add component B to pipe B of the pneumatic glue gun. When using, push the liquids in both pipes into the mixing tube at the same time, and spray them out through the atomizing head to form a film instantly.

[0038] Example 4

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

[0040] After mixing component A evenly, add it to pipe A of the pneumatic glue gun, and add component B to pipe B of the pneumatic glue gun. When using, push the liquids in both pipes into the mixing tube at the same time, and spray them out through the atomizing head to form a film instantly.

[0041] Example 5

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

[0043] After mixing component A evenly, add it to pipe A of the pneumatic glue gun, and add component B to pipe B of the pneumatic glue gun. When using, push the liquids in both pipes into the mixing tube at the same time, and spray them out through the atomizing head to form a film instantly.

[0044] Comparative Example 1

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

[0046] After mixing component A evenly, add it to pipe A of the pneumatic glue gun, and add component B to pipe B of the pneumatic glue gun. When using, push the liquids in both pipes into the mixing tube at the same time, and spray them out through the atomizing head to form a film instantly.

[0047] Comparative Example 2

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

[0049] After mixing component A evenly, add it to pipe A of the pneumatic glue gun, and add component B to pipe B of the pneumatic glue gun. When using, push the liquids in both pipes into the mixing tube at the same time, and spray them out through the atomizing head to form a film instantly.

[0050] Thermal insulation performance test: Spray a certain amount of polyurethane foam on the leveled soil surface, test the temperature 10 cm below the ground within two weeks, and calculate the average temperature increase of the soil after covering with mulch.

[0051] Soil water retention performance test: Spray the foam film evenly on the soil surface and measure the change in soil moisture content within two weeks. Take the soil 10cm below the soil surface and dry it in an oven at 105℃ to constant weight. The mass is recorded as G 1 , add a mass of G to the soil 2 of water, the mass of soil after evaporation is G 3 , calculate the soil water retention rate according to the following formula.

[0052] W(%)=(G 3 -G 1 ) / G 3×100

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

[0054] Toughness test: The elongation at break is used to characterize the toughness of polyurethane foam materials, and the test is carried out according to ABNT NBR 8515-2020.

[0055] Table 1 Performance comparison of polyurethane foam mulch

[0056]

[0057] As can be seen from the data in Table 1, compared with Comparative Examples 1 and 2, the addition of nanocellulose fiber gel and nanocellulose crystal gel can improve the comprehensive performance of polyurethane foam mulch. The tear strength of polyurethane foam mulch is significantly improved because nanocellulose has a high modulus, good wear resistance and a reinforcing effect. Comparative Example 3 and Example 4 show that the elongation at break of the polyurethane foam mulch with the addition of nanocellulose fibers is higher, 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 formation of a cross-linked foam network by nanocellulose, soybean oil polyol and diisocyanate. With the increase in nanocellulose content (Example 1, Example 3 and Example 5), the soil water retention rate increases, because the nanocellulose surface contains a large number of hydroxyl groups and is highly hydrophilic. In addition, the water retention rate of Comparative Example 2 is low, mainly because of its large size and low content.

[0058] Taking Example 3, Example 4, Comparative Example 1 and Comparative Example 2 as examples, the stability of the polyurethane foam mulch was further tested. The potted plants that had been evenly sprayed with the polyurethane foam mulch were placed in a ventilated place near the window, and the rupture of the polyurethane foam was observed at regular intervals. The following are the morphological pictures of the foam mulch taken 30 days later. Figure 2 As shown, the foam in Comparative Examples 1 and 2 partially collapsed, but still did not completely disappear, but showed the morphology of polyurethane film, which still had a certain promoting effect on the thermal insulation and water retention performance of the soil. This is because the polyurethane foam is a solid foam, and the cells are formed by cross-linking of polyols and isocyanates. It has a strong support function and is not easy to collapse. Therefore, it can stably exist on the soil surface. Compared with Comparative Examples 1 and 2, the foam mulch in Examples 3 and 4 is more uniform and dense, and there is no obvious difference in the foam after 30 days, indicating that both nanocellulose fibers and nanocellulose crystals promote 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 description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bio-based polyurethane foam ground film composition, characterized in that: The invention comprises component A and component B, wherein component A comprises soybean oil polyol, nanocellulose hydrogel, a foam leveler and a catalyst, and the catalyst is an organic tin catalyst and / or an amine catalyst; and component B is isocyanate.

2. The composition according to claim 1, characterized in that In parts by weight, the soybean oil polyol is 40-60 parts, the nanocellulose hydrogel is 0.5-10 parts, the foam leveling agent is 0.1-2 parts, the catalyst is 0.1-1 parts, and the isocyanate is 35-55 parts.

3. The composition according to claim 2, characterized in that In parts by weight, the soybean oil polyol is 50±5 parts, the nanocellulose hydrogel is 1-5 parts, the foam leveling agent is 1±0.5 parts, the catalyst is 0.5±0.2 parts, and the isocyanate is 40-50 parts.

4. The composition according to claim 3, characterized in that The foam leveling agent is dimethyl silicone oil, the isocyanate is toluene diisocyanate; the organic tin 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.

5. The composition according to claim 4, characterized in that The hydroxyl value of the soybean oil polyol is 326±20 mgKOH / g.

6. The composition according to any one of claims 1 to 5, characterized in that The nanocellulose hydrogel is a nanocellulose fiber hydrogel and / or a nanocellulose crystal hydrogel.

7. The composition according to claim 6, characterized in that The diameter of the nanocellulose fiber hydrogel is 3-5nm and the length is 500-1000nm, and the diameter of the nanocellulose crystal hydrogel is 3-5nm and the length is 200-500nm.

8. The composition according to claim 7, characterized in that The solid content of the nanocellulose hydrogel is 2.0±1.5 wt %.

9. Use of the composition according to any one of claims 1 to 8, characterized in that: Components A and B are mixed and sprayed out through a foam nozzle to form a polyurethane foam ground film.

10. The use according to claim 9, characterized in that: The following steps are involved: (1) Mix component A evenly and add it into tube A of a pneumatic glue gun; (2) Add component B into tube B of a pneumatic glue gun; (3) Turn on the air compressor switch and adjust the spraying speed. The two components of liquid in tubes A and B are mixed and sprayed out through the foam head to form a polyurethane foam film.

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