Wheat straw polyurethane synthetic leather, and preparation method and application thereof

Abstract

The application provides wheat straw polyurethane synthetic leather and a preparation method and application thereof, and the wheat straw polyurethane synthetic leather comprises a foaming layer, a bonding layer and a base cloth which are sequentially arranged, and raw materials of the foaming layer and the bonding layer all comprise liquefied wheat straw polyol, isocyanate, organosiloxane, a chain extender and a catalyst; by selecting the liquefied wheat straw polyol as the main raw material of the foaming layer and the bonding layer, not only the dependence of the polyurethane synthetic leather on petrochemical raw materials is effectively reduced, but also a new scientific and reasonable utilization way of the wheat straw as waste is provided, meanwhile, the obtained wheat straw polyurethane synthetic leather has high peeling strength, tensile strength and elongation at break, is low in price and very environment-friendly.

Description

Technical Field

[0001] This invention belongs to the field of synthetic leather technology, specifically relating to a wheat straw polyurethane synthetic leather, its preparation method, and its application. Background Technology

[0002] The production of fuels and chemicals is heavily reliant on fossil fuels. Fossil fuels provide a wide variety of necessities for our lives, but they also contribute to accelerating global warming. Biomass lignocellulosic materials are one of the most promising alternatives to fossil fuels, producing fuels and chemicals from various lignocellulosic materials such as wood, bamboo, forest or agricultural residues. However, the consumption of wood is increasing, and the number of trees worldwide has decreased to about 55% of what it has been in human history.

[0003] Agricultural residues are renewable, low-cost, and readily available biomass resources. While obtaining wheat for daily life, useless wheat straw is discarded. Wheat straw can be added to polymer formulations as a rigid filler. Wheat straw can be used as a substitute for petrochemicals as a polyol, and biomass liquefaction of wheat straw can be used to synthesize polyurethane resins. Currently, using biomass residues as raw materials, liquefied bamboo shoot shells, sugarcane bagasse, and cotton stalks have been prepared under acid catalysis and used to produce polyurethane synthetic leather.

[0004] In recent years, there have been numerous studies and reports on the preparation of biomass polyurethane using liquefied agricultural waste rice husks. CN104892958A discloses a rice husk-based polyurethane adhesive containing rice husk-based polyol and its preparation method. First, rice husk powder is liquefied under certain conditions to prepare rice husk-based polyol. Then, using rice husk-based polyol, polyester polyol, and isocyanate as raw materials, and dioxane as solvent, a polyurethane prepolymer is prepared under the action of the catalyst dibutyltin dilaurate. A small-molecule chain extender is then added to carry out a chain extension reaction, thereby obtaining a polyurethane adhesive emulsion. This invention fully utilizes inexpensive, readily available, and renewable rice husk resources, alleviating dependence on fossil resources. Furthermore, the operation process is simple and easy to control. The prepared rice husk-based polyurethane adhesive emulsion exhibits good film-forming properties, high solid content, high bonding strength, and excellent mechanical properties, giving it significant market competitiveness.

[0005] CN102617821A discloses a polyurethane foam plastic made from rice husks and its preparation method. The foam plastic formulation includes: 100-190 parts rice husks, 100-150 parts isocyanate, 0.5-5 parts chain extender / crosslinker, 2-5 parts foam stabilizer, 0.01-3 parts catalyst, and 0-10 parts foaming agent. The preparation method of the foam plastic includes the following steps: first, rice husk powder is mixed with polyethylene glycol, ethylene glycol and glycerol to form rice husk liquefaction, then the chain extender / crosslinker, catalyst, foam stabilizer and isocyanate are added, mixed evenly, poured into a mold, sealed, cured, cooled and demolded to obtain the desired product. This invention uses rice husks to prepare polyurethane foam plastic, which improves the utilization rate of rice husks and reduces the production cost of polyurethane foam. The polyurethane foam plastic of this invention has good buffering and energy absorption performance, thermal insulation performance and biodegradability, and can be used to make packaging and shock-absorbing cushioning materials and thermal insulation materials.

[0006] CN106188475A discloses a method for preparing a bio-based thermoplastic polyurethane elastomer, comprising: (1) adding bio-based polyol, molybdenum disulfide, methyl silicone oil, and antioxidant into a reaction vessel; (2) mixing bio-based diisocyanate and alkyl diol chain extender with the reaction product and catalyst of step (1) and then feeding the mixture into a twin-screw extruder to prepare a thermoplastic polyurethane elastomer by extrusion and reaction simultaneously; wherein the bio-based polyol is formulated from rapeseed oil-based polyol, rice husk-based polyol, and beet pulp-based polyol; this invention, by using bio-based polyol and bio-based diisocyanate, enables the prepared bio-based thermoplastic polyurethane elastomer to have sufficiently good heat resistance and can be widely used in building materials, public facilities, medical facilities and medical devices, or textile materials.

[0007] These studies indicate that liquefied agricultural waste can be recommended as a substitute for polyols in polyurethane (PU) resins. Therefore, utilizing renewable natural resources for liquefaction holds great potential in providing raw materials for the polymer industry. However, research literature on the preparation of polyurethane synthetic leather using partially liquefied rice husks as a raw material is scarce, and research on the preparation of polyurethane synthetic leather using liquefied wheat straw is even less.

[0008] Therefore, in order to address the above-mentioned technical problems, there is an urgent need to develop a wheat straw polyurethane synthetic leather with excellent physical properties, which uses liquefied wheat straw polyol as raw material. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a wheat straw polyurethane synthetic leather, its preparation method, and its application. The foaming layer and adhesive layer of the wheat straw polyurethane synthetic leather are both made from liquefied wheat straw polyols. It not only has high peel strength, tensile strength, and elongation at break, as well as excellent mechanical properties, but is also inexpensive and environmentally friendly, providing a new way to scientifically and rationally utilize wheat straw, which is considered waste.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a wheat straw polyurethane synthetic leather, the wheat straw polyurethane synthetic leather comprising a foaming layer, an adhesive layer and a base fabric arranged sequentially;

[0012] The raw materials for both the foaming layer and the adhesive layer include liquefied wheat straw polyol, isocyanate, organosiloxane, chain extender, and catalyst.

[0013] The wheat straw polyurethane synthetic leather provided by this invention comprises a foaming layer, an adhesive layer, and a base fabric arranged sequentially. The raw materials for both the foaming layer and the adhesive layer include liquefied wheat straw polyol, isocyanate, organosiloxane, chain extender, and catalyst. By selecting liquefied wheat straw polyol as the main raw material for the foaming layer and the adhesive layer, not only is the dependence of polyurethane synthetic leather on petrochemical raw materials effectively reduced, but a new way to scientifically and rationally utilize wheat straw, which is a waste product, is also provided. At the same time, the prepared wheat straw polyurethane synthetic leather has high peel strength, tensile strength, and elongation at break, exhibiting excellent comprehensive physical properties, and is inexpensive and environmentally friendly.

[0014] Preferably, the base fabric is a microfiber base fabric.

[0015] Preferably, the raw materials for the liquefied wheat straw polyol include wheat straw, diol, triol, and acidic compounds.

[0016] Since the liquefied wheat straw contains acidic substances, diols and triols can be used to effectively extract polyols from the liquefied wheat straw.

[0017] Preferably, the raw material for the liquefied wheat straw polyol comprises the following components in parts by weight:

[0018]

[0019] In this invention, the amount of wheat straw used in the raw materials of the liquefied wheat straw polyol is 10 to 20 parts by weight, such as 12 parts by weight, 14 parts by weight, 16 parts by weight or 18 parts by weight.

[0020] The raw material for the liquefied wheat straw polyol contains 80 to 90 parts by weight of diol, such as 80 parts by weight, 82 parts by weight, 84 parts by weight, 86 parts by weight, or 88 parts by weight.

[0021] The content of triol in the raw material of the liquefied wheat straw polyol is 1 to 3 parts by weight, such as 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, or 2.8 parts by weight.

[0022] The acidic compound content in the raw material of the liquefied wheat straw polyol is 0.015 parts by weight, 0.02 parts by weight, 0.025 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.04 parts by weight, or 0.045 parts by weight, etc.

[0023] Preferably, the diol includes any one or a combination of at least two of poly(ethylene oxide ether diol), poly(propylene oxide ether diol), or polytetrahydrofuran ether diol.

[0024] Preferably, the weight-average molecular weight of the diol is 100 to 2000, such as 200, 400, 600, 800, 1000, 1200, 1400, 1600 or 1800.

[0025] Preferably, the triol comprises any one or a combination of at least two of glycerol, trimethylolpropane, or trimethylolethane.

[0026] Preferably, the acidic compound includes nitric acid and / or sulfuric acid.

[0027] Preferably, the mass concentration of the acidic compound is 3-10%, such as 4%, 5%, 6%, 7%, 8%, or 9%. If the mass concentration of the acidic compound is too high, it will easily lead to the oxidation of oxygen functional groups in the obtained liquefied wheat straw polyol, affecting the performance of the wheat straw polyurethane synthetic leather further prepared.

[0028] Preferably, the liquefied wheat straw polyol is obtained by reacting wheat straw, diol, triol and acidic compound.

[0029] Preferably, the reaction temperature is 130–170°C, such as 140°C, 150°C, or 160°C.

[0030] Preferably, the reaction time is 70 to 120 minutes, such as 80 minutes, 90 minutes, 100 minutes, or 110 minutes.

[0031] As a preferred technical solution, the preparation method of the liquefied wheat straw polyol includes the following steps:

[0032] (A1) Wheat straw is ground, filtered and dried in sequence to obtain wheat straw powder;

[0033] (A2) The diol, triol and acidic compound are premixed, heated and then the wheat straw powder obtained in step (A1) is added. The mixture is heated again to carry out the reaction. A dehydrating agent is added and the mixture is filtered to obtain the liquefied wheat straw polyol.

[0034] Preferably, the mesh size of the sieve used for filtration in step (A1) is 20 to 50 mesh.

[0035] Preferably, the drying temperature in step (A1) is 60-120°C (e.g., 70°C, 80°C, 90°C, 100°C, or 110°C, etc.), and the time is 8-12 hours (e.g., 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, or 11.5 hours, etc.).

[0036] Preferably, the temperature at which the wheat straw powder obtained in step (A1) is added after heating in step (A2) is 70-90°C, such as 75°C, 80°C, 85°C or 90°C.

[0037] Preferably, the dehydrating agent in step (A2) includes anhydrous calcium carbonate and / or anhydrous sodium sulfate.

[0038] Preferably, the isocyanate includes any one or a combination of at least two of 4,4-diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, or hexamethylene diisocyanate.

[0039] Preferably, the organosiloxane comprises any one or a combination of at least two of γ-ureidopropyltriethoxysilane (A-1160), vinyltriethoxysilane (A-151), γ-aminopropyltriethoxysilane (KH-550) or γ-methacryloyloxypropyltrimethoxysilane (KH-570);

[0040] Preferably, the chain extender comprises any one or a combination of at least two of ethylenediamine, monoethanolamine, isophorone diamine, or 1,4-butanediol.

[0041] Preferably, the catalyst comprises any one or a combination of at least two of dibutyltin dilaurate, stannous octoate, or bismuth carboxylate.

[0042] Preferably, the raw material of the foamed layer comprises the following components in parts by weight:

[0043]

[0044] In this invention, the content of liquefied wheat straw polyol in the raw material of the foaming layer is 70 to 80 parts by weight, such as 72 parts by weight, 74 parts by weight, 76 parts by weight or 78 parts by weight.

[0045] In this invention, the isocyanate content in the raw material of the foaming layer is 20 to 30 parts by weight, such as 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, or 29 parts by weight.

[0046] In this invention, the content of organosiloxane in the raw material of the foaming layer is 1 to 4 parts by weight, such as 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight or 3.5 parts by weight.

[0047] In this invention, the catalyst content in the raw material of the foaming layer is 0.01 to 0.05 parts by weight, for example, 0.015 parts by weight, 0.02 parts by weight, 0.025 parts by weight, 0.03 parts by weight, 0.035 parts by weight, 0.04 parts by weight or 0.045 parts by weight, etc.

[0048] Preferably, the raw material of the foaming layer further includes 1 to 4 parts by weight (e.g., 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, or 3.5 parts by weight, etc.) of surfactant.

[0049] Preferably, the raw material of the adhesive layer comprises the following components in parts by weight:

[0050]

[0051] In this invention, the content of liquefied wheat straw polyol in the raw material of the adhesive layer is 70-80 parts by weight, such as 72 parts by weight, 74 parts by weight, 76 parts by weight or 78 parts by weight.

[0052] In this invention, the isocyanate content in the raw material of the adhesive layer is 20 to 30 parts by weight, such as 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, or 29 parts by weight.

[0053] In this invention, the content of organosiloxane in the raw material of the adhesive layer is 1 to 4 parts by weight, such as 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight or 3.5 parts by weight.

[0054] In this invention, the catalyst content in the raw material of the adhesive layer is 0.01 to 0.05 parts by weight, for example, 0.015 parts by weight, 0.02 parts by weight, 0.025 parts by weight, 0.03 parts by weight, 0.035 parts by weight, 0.04 parts by weight or 0.045 parts by weight, etc.

[0055] Preferably, the raw material of the adhesive layer further includes 1 to 4 parts by weight (e.g., 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, or 3.5 parts by weight, etc.) of surfactant.

[0056] In this invention, the surfactants in the raw materials of the foaming layer and the adhesive layer each independently include any one or a combination of at least two of SDS, CTAB, or P123.

[0057] In a second aspect, the present invention provides a method for preparing wheat straw polyurethane synthetic leather as described in the first aspect, the preparation method comprising the following steps:

[0058] (1) A mixture is prepared by mixing liquefied wheat straw polyol, isocyanate, organosiloxane, chain extender, catalyst and optional surfactant;

[0059] (2) Coat the mixture obtained in step (1) onto release paper, dry and cure to form a foamed layer;

[0060] (3) Coat one side of the foamed layer obtained in step (2) with the mixture obtained in step (1), attach the base fabric, dry and cure to obtain the wheat straw polyurethane synthetic leather.

[0061] The wheat straw polyurethane synthetic leather provided by the present invention firstly mixes liquefied wheat straw polyol, isocyanate, organosiloxane, chain extender, catalyst and optional surfactant to obtain a mixture; then the obtained mixture is coated on release paper, dried and cured to foam to obtain a foamed layer; finally, the obtained mixture is coated on the foamed layer as an adhesive, bonded to the base fabric, and dried and cured to obtain the wheat straw polyurethane synthetic leather.

[0062] Preferably, the mixing time in step (1) is 30 to 60 seconds, such as 35 seconds, 40 seconds, 45 seconds, 50 seconds, or 55 seconds.

[0063] Preferably, the coating thickness in step (2) is 0.5 to 2 mm, such as 0.7 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, 1.7 mm or 1.9 mm.

[0064] Preferably, the drying, curing and foaming temperature in step (2) is 80 to 120°C, such as 85°C, 90°C, 95°C, 100°C, 105°C, 110°C or 115°C.

[0065] Preferably, the drying, curing and foaming time in step (2) is 20 to 40 minutes, such as 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes or 38 minutes.

[0066] Preferably, the coating thickness in step (3) is 0.1 to 1 mm, for example, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm or 0.9 mm.

[0067] Preferably, the drying and curing temperature in step (3) is 100 to 140°C, such as 110°C, 120°C or 130°C.

[0068] Preferably, the drying and curing time in step (3) is 10 to 30 minutes, such as 12 minutes, 14 minutes, 16 minutes, 18 minutes, 20 minutes, 22 minutes, 24 minutes, 26 minutes or 28 minutes.

[0069] Thirdly, the present invention provides an application of wheat straw polyurethane synthetic leather as described in the first aspect in the field of footwear leather.

[0070] Compared with the prior art, the present invention has the following beneficial effects:

[0071] (1) The wheat straw polyurethane synthetic leather provided by the present invention includes a foaming layer, an adhesive layer and a base fabric arranged in sequence, and the raw materials of the foaming layer and the adhesive layer include liquefied wheat straw polyol, isocyanate, organosiloxane, chain extender and catalyst; by selecting liquefied wheat straw polyol to replace the polyol prepared from petrochemical raw materials as the raw material for the foaming layer and adhesive layer of synthetic leather, the reliance on petrochemical raw materials is effectively reduced, and a scientific and reasonable new use for waste wheat straw is provided;

[0072] (2) Since wheat straw resources are abundant, inexpensive, and can be liquefied under normal pressure, the wheat straw polyurethane polyol provided by this invention has very low requirements for preparation equipment and is easy to operate;

[0073] (3) The wheat straw polyurethane synthetic leather provided by the present invention also has high peel strength, tensile strength and elongation at break, excellent comprehensive physical properties and is very environmentally friendly. Detailed Implementation

[0074] The present invention will be further described below with reference to specific embodiments; it should be understood that these specific embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention; furthermore, it should be understood that after reading the contents of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0075] Unless otherwise specified, the raw materials involved in the specific embodiments of this invention are all conventional materials in the art and can be purchased commercially.

[0076] Preparation Example 1

[0077] A liquefied wheat straw polyol, the raw materials for its preparation include the following components in parts by weight:

[0078]

[0079] The weight-average molecular weight of the polyoxyethylene ether diol is 100, and the mass concentration of nitric acid is 3%.

[0080] The preparation method of liquefied wheat straw polyol provided in this embodiment includes the following steps:

[0081] (1) Grind the wheat straw in a grinder, filter it through a 20-mesh sieve, and then dry it in an oven at 60°C for 12 hours to obtain wheat straw powder.

[0082] (2) Polyethylene oxide ether diol, glycerol and nitric acid were added to a glass flask equipped with a stirrer, thermometer and reflux condenser for premixing. After stirring evenly, the temperature was raised to 70°C. Then the wheat straw powder obtained in step (1) was added. The reaction flask was then heated to 130°C and kept at that temperature for 120 min. Finally, anhydrous sodium sulfate was added to remove the water. The mixture was then filtered to obtain the liquefied wheat straw polyol.

[0083] Preparation Example 2

[0084] A liquefied wheat straw polyol, the raw materials for its preparation include the following components in parts by weight:

[0085]

[0086] The weight-average molecular weight of the polyoxypropylene ether diol is 1000, and the mass concentration of sulfuric acid is 3%.

[0087] The preparation method of liquefied wheat straw polyol provided in this embodiment includes the following steps:

[0088] (1) Grind the wheat straw in a grinder, filter it using a 30-mesh sieve, and then dry it in an oven at 90°C for 10 hours to obtain wheat straw powder;

[0089] (2) Polyethylene oxide ether diol, glycerol and nitric acid were added to a glass flask equipped with a stirrer, thermometer and reflux condenser for premixing. After stirring evenly, the temperature was raised to 80°C. Then the wheat straw powder obtained in step (1) was added. The reaction flask was then heated to 150°C and kept at that temperature for 90 min. Finally, anhydrous calcium chloride was added to remove the water. The mixture was then filtered to obtain the liquefied wheat straw polyol.

[0090] Preparation Example 3

[0091] A liquefied wheat straw polyol, the raw materials for its preparation include the following components in parts by weight:

[0092]

[0093] The polytetrahydrofuran ether diol has a weight-average molecular weight of 2000 and a nitric acid mass concentration of 3%.

[0094] The preparation method of liquefied wheat straw polyol provided in this embodiment includes the following steps:

[0095] (1) Grind the wheat straw in a grinder, filter it through a 50-mesh sieve, and then dry it in an oven at 120°C for 8 hours to obtain wheat straw powder.

[0096] (2) Polyethylene oxide ether diol, glycerol and nitric acid were added to a glass flask equipped with a stirrer, thermometer and reflux condenser for premixing. After stirring evenly, the temperature was raised to 90°C. Then the wheat straw powder obtained in step (1) was added. The reaction flask was then heated to 170°C and kept warm for 70 min. Finally, anhydrous sodium sulfate was added to remove the water. The mixture was then filtered to obtain the liquefied wheat straw polyol.

[0097] Preparation Example 4

[0098] A liquefied wheat straw polyol differs from Preparation Example 1 in that the amount of polyoxyethylene ether diol added is 83 parts by weight, and no glycerol is added. The other substances, amounts, and preparation methods are the same as in Preparation Example 1.

[0099] Preparation Example 5

[0100] A liquefied wheat straw polyol differs from Preparation Example 1 in that the amount of glycerol added is 83 parts by weight, and no polyoxyethylene ether diol is added. All other substances, amounts, and preparation methods are the same as in Preparation Example 1.

[0101] Preparation Example 6

[0102] A liquefied wheat straw polyol differs from Preparation Example 1 in that the mass concentration of nitric acid is 20%, while the other substances, amounts, and preparation methods are the same as in Preparation Example 1.

[0103] Example 1

[0104] A wheat straw polyurethane synthetic leather, comprising a foaming layer, an adhesive layer and a base fabric layer arranged sequentially;

[0105] The raw materials for preparing the foamed layer and the adhesive layer each include the following components in parts by weight:

[0106]

[0107] In this case, the liquefied wheat straw polyol was prepared from Example 1, the organosiloxane was organosiloxane A-150, and the surfactant was surfactant SDS.

[0108] The method for preparing wheat straw polyurethane synthetic leather provided in this embodiment includes the following steps:

[0109] (1) Add liquefied wheat straw polyol, 4,4-diphenylmethane diisocyanate, organosiloxane, dibutyltin dilaurate, ethylenediamine and surfactant to a reaction beaker and stir evenly for 30s to obtain a mixture;

[0110] (2) The mixture obtained in step (1) is evenly coated on the surface of the release paper with a coating thickness of 0.5 mm, and then placed in an 80℃ oven for 40 min to dry, cure and foam, to obtain a foamed layer.

[0111] (3) A layer of the mixture obtained in step (1) is coated on the surface of the foamed layer dried in step (2) with a coating thickness of 0.1 mm. Then, a microfiber base fabric (the base fabric is from Tongda Microfiber) is attached and then placed in an oven at 100°C for 30 min to obtain the wheat straw polyurethane synthetic leather.

[0112] Example 2

[0113] A wheat straw polyurethane synthetic leather, comprising a foaming layer, an adhesive layer and a base fabric layer arranged sequentially;

[0114] The raw materials for preparing the foamed layer and the adhesive layer each include the following components in parts by weight:

[0115]

[0116] In this case, the liquefied wheat straw polyol was prepared from Example 2, the organosiloxane was organosiloxane A-1160, and the surfactant was surfactant CTAB;

[0117] The method for preparing wheat straw polyurethane synthetic leather provided in this embodiment includes the following steps:

[0118] (1) Add liquefied wheat straw polyol, toluene diisocyanate, organosiloxane, monoethanolamine, stannous octoate and surfactant to a reaction beaker and stir for 40 seconds to obtain a mixture;

[0119] (2) The mixture obtained in step (1) is evenly coated on the surface of the release paper with a coating thickness of 1 mm, and then placed in a 100°C oven for 30 min to dry, cure and foam, to obtain a foamed layer.

[0120] (3) Apply another layer of the mixture obtained in step (1) to the surface of the foamed layer dried in step (2), with a coating thickness of 0.5 mm, and then attach the microfiber base fabric (the base fabric is from Tongda Microfiber), and then put it in an oven at 120°C for 20 min to obtain the wheat straw polyurethane synthetic leather.

[0121] Example 3

[0122] A wheat straw polyurethane synthetic leather, comprising a foaming layer, an adhesive layer and a base fabric layer arranged sequentially;

[0123] The raw materials for preparing the foamed layer and the adhesive layer each include the following components in parts by weight:

[0124]

[0125] In this case, the liquefied wheat straw polyol was prepared from Example 3, the organosiloxane was organosiloxane KH-550, and the surfactant was surfactant P123.

[0126] The method for preparing wheat straw polyurethane synthetic leather provided in this embodiment includes the following steps:

[0127] (1) Liquefied wheat straw polyol, isophorone diisocyanate, organosiloxane, bismuth carboxylate, 1,4-butanediol and surfactant were added to a reaction beaker for drying, curing and foaming. The mixture was stirred for 60 seconds to obtain a mixture.

[0128] (2) The mixture obtained in step (1) is evenly coated on the surface of the release paper with a coating thickness of 2 mm, and then placed in an oven at 120°C for 30 min to obtain a foamed layer.

[0129] (3) Apply another layer of the mixture obtained in step (1) to the surface of the foamed layer dried in step (2), with a coating thickness of 1 mm, and then attach the microfiber base fabric (the base fabric is from Tongda Microfiber), and then put it in an oven at 140°C for 10 min to obtain the wheat straw polyurethane synthetic leather.

[0130] Examples 4-6

[0131] A wheat straw polyurethane synthetic leather differs from Example 1 in that the liquefied wheat straw polyol provided in Preparation Examples 4-6 is used instead of the liquefied wheat straw polyol provided in Preparation Example 1, while the other substances, amounts, and preparation methods are the same as in Example 1.

[0132] Example 7

[0133] A wheat straw polyurethane synthetic leather differs from Example 1 in that no surfactant is added, while the other substances, amounts, and preparation methods are the same as in Example 1.

[0134] Example 8

[0135] A wheat straw polyurethane synthetic leather differs from Example 1 in that the stirring time in step (1) is 5 minutes, while the other substances, amounts, and preparation methods are the same as in Example 1.

[0136] Comparative Example 1

[0137] A wheat straw polyurethane synthetic leather differs from Example 1 in that no organosiloxanes are added, while the other substances, dosages, and preparation methods are the same as in Example 1.

[0138] Performance testing:

[0139] (1) Peel strength: Tested using a tensile testing machine, the test method is in accordance with GB / T 3903.3-2011;

[0140] (2) Tensile strength and elongation at break: The test shall be conducted in accordance with the method provided in GB / T 38612-2020.

[0141] Based on the above test results, the liquefied wheat straw polyurethane synthetic leathers provided in Examples 1-8 and Comparative Example 1 were tested, and the test results are shown in Table 1:

[0142] Table 1

[0143]

[0144]

[0145] According to the data in Table 1:

[0146] The wheat straw polyurethane synthetic leather provided in Examples 1-3 has a peel strength of 75-86 N, a tensile strength of 47.12-50.55 MPa, and an elongation at break of 477.46-508.72%, exhibiting good elongation at break, tensile strength, and peel strength.

[0147] The raw material of the liquefied wheat straw polyol used in the wheat straw polyurethane synthetic leather provided in Example 4 did not contain glycerin, and the raw material of the liquefied wheat straw polyol used in the wheat straw polyurethane synthetic leather provided in Example 5 did not contain polyoxyethylene ether glycol. Both of these factors resulted in a decrease in physical properties, including a decrease in peel strength, a decrease in tensile strength, and a decrease in elongation at break.

[0148] The concentration of nitric acid in the raw material of liquefied wheat straw polyol used in the wheat straw polyurethane synthetic leather provided in Example 6 is too high, which easily oxidizes some of the functional groups, resulting in a decrease in the elongation at break, tensile strength and peel strength of the final wheat straw polyurethane synthetic leather.

[0149] The raw materials for the wheat straw polyurethane synthetic leather provided in Example 7 lack surfactants, resulting in poor compatibility with other raw materials. Consequently, the elongation at break, tensile strength, and peel strength of the final wheat straw polyurethane synthetic leather decrease.

[0150] The wheat straw polyurethane synthetic leather provided in Example 8 experienced partial foaming due to excessive mixing time of the raw materials, resulting in a decrease in the elongation at break, tensile strength, and peel strength of the prepared wheat straw polyurethane synthetic leather.

[0151] The wheat straw polyurethane synthetic leather provided in Comparative Example 1 lacks organosiloxanes, which cannot play a good role in curing and bonding, resulting in a serious decrease in peel strength.

[0152] The applicant declares that this invention illustrates a wheat straw polyurethane synthetic leather, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in the product, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A wheat straw polyurethane synthetic leather, characterized in that, The wheat straw polyurethane synthetic leather comprises a foaming layer, an adhesive layer, and a base fabric arranged sequentially. The raw material for the foamed layer comprises the following components in parts by weight: 70-80 parts by weight of liquefied wheat straw polyol; 20-30 parts by weight of isocyanate; 1-4 parts by weight of organosiloxane; Chain extender 2-5 parts by weight; Catalyst: 0.01~0.05 parts by weight; 1-4 parts by weight of surfactant; The raw material of the adhesive layer comprises the following components in parts by weight: 70-80 parts by weight of liquefied wheat straw polyol; 20-30 parts by weight of isocyanate; 1-4 parts by weight of organosiloxane; Chain extender 2-5 parts by weight; Catalyst: 0.01~0.05 parts by weight; 1-4 parts by weight of surfactant; The surfactants in the raw materials of the foaming layer and the adhesive layer each independently include any one or a combination of at least two of SDS, CTAB, or P123; The organosiloxanes in the raw materials of the foaming layer and the adhesive layer each independently include any one or a combination of at least two of γ-ureidopropyltriethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane or γ-methacryloyloxypropyltrimethoxysilane; The raw materials for the liquefied wheat straw polyol include the following components in parts by weight: 10-20 parts by weight of wheat straw; 80-90 parts by weight of diol; 1-3 parts by weight of triol; 0.01~0.05 parts by weight of acidic compound; The diol includes any one or a combination of at least two of polyoxyethylene ether diol, polyoxypropylene ether diol, or polytetrahydrofuran ether diol. The mass concentration of the acidic compound is 3-10%.

2. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The base fabric is a microfiber base fabric.

3. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The weight-average molecular weight of the diol is 100-2000.

4. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The triol includes any one or a combination of at least two of glycerol, trimethylolpropane, or trimethylolethane.

5. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The acidic compounds include nitric acid and / or sulfuric acid.

6. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The liquefied wheat straw polyol is obtained by reacting wheat straw, diol, triol and acidic compound.

7. The wheat straw polyurethane synthetic leather according to claim 6, characterized in that, The reaction is carried out at a temperature of 130-170°C for a time of 70-120 minutes.

8. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The isocyanate includes any one or a combination of at least two of 4,4-diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, or hexamethylene diisocyanate.

9. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The chain extender includes any one or a combination of at least two of ethylenediamine, monoethanolamine, isophorone diamine, or 1,4-butanediol.

10. The wheat straw polyurethane synthetic leather according to claim 1, characterized in that, The catalyst comprises any one or a combination of at least two of dibutyltin dilaurate, stannous octoate, or bismuth carboxylate.

11. A method for preparing wheat straw polyurethane synthetic leather as described in any one of claims 1 to 10, characterized in that, The preparation method includes the following steps: (1) Mix liquefied wheat straw polyol, isocyanate, organosiloxane, chain extender, catalyst and surfactant to obtain a mixture; (2) Coat the mixture obtained in step (1) onto release paper, dry and cure to form a foamed layer; (3) The mixture obtained in step (1) is coated on one side of the foam layer obtained in step (2), the base fabric is attached, and the mixture is dried and cured to obtain the wheat straw polyurethane synthetic leather.

12. The preparation method according to claim 11, characterized in that, The mixing time in step (1) is 30~60s.

13. The preparation method according to claim 11, characterized in that, The coating thickness in step (2) is 0.5~2mm.

14. The preparation method according to claim 11, characterized in that, The drying, curing, and foaming temperature in step (2) is 80~120℃.

15. The preparation method according to claim 11, characterized in that, The drying, curing, and foaming time in step (2) is 20~40 min.

16. The preparation method according to claim 11, characterized in that, The coating thickness in step (3) is 0.1~1mm.

17. The preparation method according to claim 11, characterized in that, The drying and curing temperature in step (3) is 100~140℃.

18. The preparation method according to claim 11, characterized in that, The drying and curing time in step (3) is 10~30 min.

19. The application of wheat straw polyurethane synthetic leather as described in any one of claims 1 to 10 in the field of footwear leather.

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