Preparation method of oxypropylated cotton spinning black liquid-based polyurethane oil-water separation sponge

Abstract

The invention discloses a method for preparing an oxypropylated cotton spinning black liquor-based polyurethane oil-water separation sponge, which belongs to the technical field of polyurethane sponges, and comprises the following steps: preparing a cotton spinning black liquor extract; extracting organic matter from the cotton spinning black liquor extract; preparing an oxypropylated cotton spinning black liquor extract; preparing an oxypropylated modified black liquor precipitate-based polyurethane sponge; and preparing an oxypropylated cotton spinning black liquor-based polyurethane oil-water separation sponge. The solution provided by the invention can effectively solve the problems faced by the cotton textile and biochemical industries in black liquor treatment. The invention successfully extracts organic matter from cotton spinning black liquor, and after modification, uses it as biopolyol to replace fossil fuel polyol to prepare a polyurethane soft sponge. The prepared sponge is hydrophobically modified to have oil-water separation performance, successfully realizing the recycling of resources, effectively closing the recycling chain of resource utilization, and laying a solid foundation for the sustainable development of the polyurethane industry.

Description

Technical Field

[0001] The invention belongs to the field of polyurethane sponges, and specifically relates to a method for preparing an oxypropylated cotton spinning black liquid-based polyurethane oil-water separation sponge. Background Art

[0002] Polyurethane is widely used in many fields such as fibers, coatings, adhesives, insulation, construction, furniture and medical devices. It is one of the most widely used specialty components in the polymer family. As the sixth most used polymer in the world, its market share accounts for about 8% of the total global polymer market. Despite its wide application, the production of polyurethane is still highly dependent on petroleum fuels. At the same time, the strong toxicity of its production raw materials requires high levels of storage and transportation standards. Therefore, the industry needs to constantly adapt to increasingly stringent regulations and strict consumer requirements. In this context, there is an urgent need to adopt renewable raw materials and new process technologies to prepare polyurethanes that are environmentally friendly and meet the requirements of sustainable development. Traditionally, the synthesis of polyurethane is achieved by addition polymerization between the hydroxyl group of polyols and the isocyanate functional group of isocyanates. Based on this, in recent years, researchers have shown increasing interest in extracting bio-based polyols from biomass to replace fossil polyols and isocyanates to prepare polyurethanes. Compared with fossil fuels that are facing depletion, there are abundant biomass resources in nature, which have the advantages of environmental friendliness and low toxicity. Moreover, most biomass is rich in hydroxyl groups and can be used as a raw material for bio-based polyols for polyurethane preparation. Common biomass polyol raw materials include refined vegetable oil, lignin and cellulose. In recent years, forestry and agricultural waste, by-products of the food and beverage industry, etc. have gradually come into view. These wastes not only contain a large amount of biomass organic matter, but also have low cost and low utilization rate. Converting waste into valuable resources can turn waste into treasure, improve the utilization rate of divergent resources, and turn waste into treasure.

[0003] Cotton spinning black liquor is wastewater generated in the production of viscose fibers. It originates from the alkaline cooking of cotton linters. The pH value of black liquor is about 11, the COD value is as high as 40,000 mg / L, and the organic matter content can reach 65%. Black liquor is a high-concentration organic wastewater because it contains rich cotton linters, as well as dissolved cellulose, hemicellulose, wax, oil and pectin decomposed under high temperature and alkaline conditions. In addition, black liquor also contains the decomposition products of these substances, such as various oligosaccharides, fatty acid salts, fatty alcohols, formaldehyde, acetic acid, sugars and other organic substances that are easily biodegradable.

[0004] Although black liquor is a kind of production wastewater, the rich organic matter in it makes it an excellent source of low-quality waste biomass. Biomass can be converted into liquid polyols through oxypropylation or liquefaction processes, and the liquid polyols produced from these biomass can be used to prepare various polyurethane products, including foams, films and adhesives. Based on this characteristic, the appropriate method can be used to extract and oxypropylate the biomass organic matter from black liquor to improve its biocompatibility, providing a feasible way for the preparation of polyurethane materials.

[0005] Therefore, it is a technical problem that those skilled in the art need to solve urgently to provide a polyurethane sponge with excellent oil-water separation performance by oxypropylation modification of cotton spinning black liquor extract. Summary of the invention

[0006] In view of this, the present invention performs oxypropyl modification on cotton spinning black liquor extract, replaces fossil polyols with it, prepares biomass polyols, and then synthesizes polyurethane sponges. The biomass sponge is hydrophobically modified to prepare an oxypropylated cotton spinning black liquor-based polyurethane oil-water separation sponge.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing an oxypropylated cotton spinning black liquid-based polyurethane oil-water separation sponge comprises the following steps:

[0009] (1) Preparing a cotton spinning black liquor extract: mixing the cotton spinning black liquor with anhydrous ethanol, stirring the mixture thoroughly and then standing the mixture for 6 hours, then taking the supernatant and evaporating and drying the mixture to obtain a cotton spinning black liquor extract;

[0010] (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to an organic solvent for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the organic solvent, thereby obtaining the organic matter in the cotton spinning black liquor;

[0011] (3) Preparation of oxypropylated cotton spinning black liquor extract:

[0012] The organic matter in the cotton textile black liquor is added into a high-pressure reactor, and then propylene oxide, potassium hydroxide and acetone are added into the reactor, and then anhydrous glycerin is added. During the reaction, the reactor is kept in a high-pressure state (2.5 to 4 atmospheres) and stirred to obtain an oxypropylated cotton textile black liquor extract, which is recorded as OBLP (Oxypropylation cotton textile black liquor precipitate);

[0013] (4) Preparation of oxypropyl modified black liquor extract-based polyurethane sponge:

[0014] High resilience polyether alcohol, OBLP, dichloromethane, water, 33% triethylenediamine solution and silicone oil surfactant were mixed, and stirred vigorously at 1000rpm for 30s, then toluene diisocyanate and stannous octoate were added, and stirring was continued until the mixed solution became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, and the material was cured after being formed to obtain an oxypropylation modified black liquid precipitate based polyurethane sponge, which was recorded as OBLPPUF (Oxypropylation black liquid precipitate based polyurethane sponge);

[0015] (5) Preparation of oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane, stirred for 6 h, and then ultrasonically treated; the ultrasonicated material was rinsed with distilled water and n-hexane, respectively, and the excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45°C to 50°C for 8 to 12 h to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, denoted as OTS-OBLPPUF.

[0016] Furthermore, the mass ratio of the cotton spinning black liquor to anhydrous ethanol in step (1) is 1:3 to 1:5.

[0017] Furthermore, the organic solvent in step (2) is any one of n-hexane, cyclopentane, ethyl acetate, acetone and n-propanol.

[0018] Furthermore, the mass ratio of organic matter, propylene oxide, potassium hydroxide, acetone and anhydrous glycerin in the cotton spinning black liquor in step (3) is 10-30:10-30:1-3:30-50:3-10.

[0019] Furthermore, in step (3), the reaction temperature is 120-180° C., the reaction time is 1.5-3 h, and the stirring rate is 300-500 rpm.

[0020] Furthermore, in step (4), the following raw materials are used to prepare OBLP PUF in parts by weight: 28-38 parts of high resilience polyether alcohol, 2-12 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution (mass fraction), 0.45 parts of silicone oil surfactant, 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate.

[0021] In the solution of the present invention, high resilience polyether alcohol, 33% triethylenediamine solution, silicone oil surfactant, toluene diisocyanate and stannous octoate are all purchased from China Resources Chemical.

[0022] The high resilience polyether alcohol is polyether 330N, the 33% triethylenediamine solution is A-33, and the silicone oil surfactant is L580.

[0023] Furthermore, in step (4), the oven temperature is 28-30° C., and the molding and curing time is 48 hours.

[0024] Furthermore, in the mixed solution of trichloro(octadecyl)silane and n-hexane in step (5), the volume ratio of trichloro(octadecyl)silane to n-hexane is 1:40.

[0025] Furthermore, in step (5), the ultrasonic power is 40 Hz and the ultrasonic time is 10 to 15 minutes.

[0026] The beneficial effect of the present invention is that the solution provided by the present invention can effectively solve the common problems faced by the cotton textile and biochemical industries in southern Xinjiang in the treatment of black liquor, including the difficulty in treating black liquor, serious pollution, high treatment costs and other problems. By developing low-cost key technologies for environmentally friendly treatment and high-value utilization of cotton spinning black liquor, the present invention successfully extracted the main organic matter in the cotton spinning black liquor, and modified it as biopolyol to replace fossil fuel polyol to prepare polyurethane soft sponge. Subsequently, the prepared sponge was hydrophobically modified to have oil-water separation performance, and it was applied to the separation of grease in cotton spinning black liquor, successfully realizing the recycling of resources, effectively closing the recycling chain of resource utilization, and laying a solid foundation for the sustainable development of the polyurethane industry.

[0027] The oxypropylated cotton spinning black liquor extract-based polyurethane sponge prepared by the present invention exhibits good performance. Its contact angle can reach a maximum of 137.75°, and when the modified black liquor extract replaces 15%, the apparent morphology and mechanical properties are the best. At the same time, the maximum oil adsorption rate of the sponge can reach 2791.8%, and after 5 cycles of oil absorption, it can still maintain good oil absorption performance. After the obtained sponge is applied to the oil pretreatment of cotton spinning black liquor, the oil-water separation rate of the sponge obtains an effect that is relatively close to the oil extraction result. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 SEM images of polyurethane sponges prepared with different replacement amounts of oxypropylated cotton spinning black liquor extract;

[0029] Figure 2 The apparent density of polyurethane sponges prepared by replacing different amounts of oxypropylated cotton spinning black liquor extract;

[0030] Figure 3 The compressive strength of polyurethane sponges prepared by replacing different amounts of oxypropylated cotton spinning black liquor extract;

[0031] Figure 4The hydrophobic effect diagram of the sponge prepared by the present invention: a) Different effects of dropping water droplets and soybean oil on the surface of the sponge; b) The sponge is immersed in water to produce a silver mirror effect and float on the water surface; c) The sponge absorbs oil in the oil-water mixture;

[0032] Figure 5 Water contact angle of polyurethane oil-absorbing sponges prepared with different replacement amounts of oxypropylated cotton spinning black liquor extract;

[0033] Figure 6 Maximum oil adsorption rate of polyurethane oil-absorbing sponges prepared by replacing different amounts of oxypropylated cotton spinning black liquor extract;

[0034] Figure 7 Repeated oil absorption rate of polyurethane oil-absorbing sponges prepared with different replacement amounts of oxypropylated cotton spinning black liquor extract. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] 5wt% oxypropylated cotton black liquid-based polyurethane oil-water separation sponge:

[0038] (1) Preparing a cotton spinning black liquor extract: mixing cotton spinning black liquor with anhydrous ethanol in a mass ratio of 1:3, stirring thoroughly and then standing for 6 hours, then taking the supernatant and evaporating and drying it to obtain a cotton spinning black liquor extract;

[0039] (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to cyclopentane for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the cyclopentane, thereby obtaining the organic matter in the cotton spinning black liquor;

[0040] (3) Preparation of oxypropylated cotton spinning black liquor extract:

[0041] 20 g of organic matter in cotton spinning black liquor was added to a high-pressure reactor, and then 20 g of propylene oxide, 1 g of potassium hydroxide and 40 g of acetone were added to the reactor, and then 5 g of anhydrous glycerol was added to the reactor, and the reaction was carried out at 150° C. for 2 h, while the reactor was kept in a high pressure state (3 atmospheres) and stirred at a speed of 400 rpm to obtain an oxypropyl-modified cotton spinning black liquor extract, which was recorded as OBLP;

[0042] (4) Preparation of oxypropyl modified black liquor precipitate based polyurethane sponge:

[0043] 38 parts of high resilience polyether alcohol, 2 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution and 0.45 parts of silicone oil surfactant were mixed, and vigorously stirred at 1000 rpm for 30 seconds, and then 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate were added, and stirring was continued until the mixed solution became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, the temperature was set at 28-30°C, and the material was waited for molding and curing for 48 hours to obtain an oxypropyl modified black liquor precipitate-based polyurethane sponge, which was recorded as OBLPPUF-5;

[0044] (5) Preparation of oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane (1 ml:40 ml) and stirred for 6 h, and then ultrasonically treated at 40 Kz for 10 min; the ultrasonicated material was rinsed with distilled water and n-hexane, and the excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45 °C for 12 h to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, which was recorded as OTS-OBLPPUF-5.

[0045] Example 2

[0046] 10wt% oxypropylated cotton black liquid-based polyurethane oil-water separation sponge:

[0047] (1) Preparing a cotton spinning black liquor extract: mixing cotton spinning black liquor with anhydrous ethanol in a mass ratio of 1:3, stirring thoroughly and then standing for 6 hours, then taking the supernatant and evaporating and drying it to obtain a cotton spinning black liquor extract;

[0048] (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to cyclopentane for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the cyclopentane, thereby obtaining the organic matter in the cotton spinning black liquor;

[0049] (3) Preparation of oxypropylated cotton spinning black liquor extract:

[0050] 20 g of organic matter in cotton spinning black liquor was added to a high-pressure reactor, and then 20 g of propylene oxide, 1 g of potassium hydroxide and 40 g of acetone were added to the reactor, and then 5 g of anhydrous glycerol was added to the reactor, and the reaction was carried out at 150° C. for 2 h, while the reactor was kept in a high pressure state (3 atmospheres) and stirred at a speed of 400 rpm to obtain an oxypropyl-modified cotton spinning black liquor extract, which was recorded as OBLP;

[0051] (4) Preparation of oxypropyl modified black liquor precipitate based polyurethane sponge:

[0052] 36 parts of high resilience polyether alcohol, 4 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution and 0.45 parts of silicone oil surfactant were mixed, and vigorously stirred at 1000 rpm for 30 seconds, and then 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate were added, and stirring was continued until the mixed solution became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, the temperature was set at 28-30°C, and the material was waited for molding and curing for 48 hours to obtain an oxypropyl modified black liquor precipitate-based polyurethane sponge, which was recorded as OBLPPUF-10;

[0053] (5) Preparation of oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane (1 ml:40 ml) and stirred for 6 h, and then ultrasonically treated at 40 Kz for 10 min; the ultrasonicated material was rinsed with distilled water and n-hexane, and the excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45 °C for 12 h to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, which was recorded as OTS-OBLPPUF-10.

[0054] Example 3

[0055] 15wt% oxypropylated cotton black liquid-based polyurethane oil-water separation sponge:

[0056] (1) Preparing a cotton spinning black liquor extract: mixing cotton spinning black liquor with anhydrous ethanol in a mass ratio of 1:3, stirring thoroughly and then standing for 6 hours, then taking the supernatant and evaporating and drying it to obtain a cotton spinning black liquor extract;

[0057] (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to cyclopentane for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the cyclopentane, thereby obtaining the organic matter in the cotton spinning black liquor;

[0058] (3) Preparation of oxypropylated cotton spinning black liquor extract:

[0059] 20 g of organic matter in cotton spinning black liquor was added to a high-pressure reactor, and then 20 g of propylene oxide, 1 g of potassium hydroxide and 40 g of acetone were added to the reactor, and then 5 g of anhydrous glycerol was added to the reactor, and the reaction was carried out at 150° C. for 2 h, while the reactor was kept in a high pressure state (3 atmospheres) and stirred at a speed of 400 rpm to obtain an oxypropyl-modified cotton spinning black liquor extract, which was recorded as OBLP;

[0060] (4) Preparation of oxypropyl modified black liquor precipitate based polyurethane sponge:

[0061] 34 parts of high resilience polyether alcohol, 6 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution and 0.45 parts of silicone oil surfactant were mixed, and vigorously stirred at 1000 rpm for 30 seconds, and then 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate were added, and stirring was continued until the mixed solution became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, the temperature was set at 28-30°C, and the material was waited for molding and curing for 48 hours to obtain an oxypropyl modified black liquor precipitate-based polyurethane sponge, which was recorded as OBLPPUF-15;

[0062] (5) Preparation of oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane (1 ml:40 ml) and stirred for 6 h, and then ultrasonically treated at 40 Kz for 10 min; the ultrasonicated material was rinsed with distilled water and n-hexane, and the excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45 °C for 12 h to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, which was recorded as OTS-OBLPPUF-15.

[0063] Example 4

[0064] 20wt% oxypropylated cotton black liquid-based polyurethane oil-water separation sponge:

[0065] (1) Preparing a cotton spinning black liquor extract: mixing cotton spinning black liquor with anhydrous ethanol in a mass ratio of 1:3, stirring thoroughly and then standing for 6 hours, then taking the supernatant and evaporating and drying it to obtain a cotton spinning black liquor extract;

[0066] (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to cyclopentane for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the cyclopentane, thereby obtaining the organic matter in the cotton spinning black liquor;

[0067] (3) Preparation of oxypropylated cotton spinning black liquor extract:

[0068] 20 g of organic matter in cotton spinning black liquor was added to a high-pressure reactor, and then 20 g of propylene oxide, 1 g of potassium hydroxide and 40 g of acetone were added to the reactor, and then 5 g of anhydrous glycerol was added to the reactor, and the reaction was carried out at 150° C. for 2 h, while the reactor was kept in a high pressure state (3 atmospheres) and stirred at a speed of 400 rpm to obtain an oxypropyl-modified cotton spinning black liquor extract, which was recorded as OBLP;

[0069] (4) Preparation of oxypropyl modified black liquor precipitate based polyurethane sponge:

[0070] 32 parts of high resilience polyether alcohol, 8 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution and 0.45 parts of silicone oil surfactant were mixed, and vigorously stirred at 1000 rpm for 30 seconds, and then 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate were added, and stirring was continued until the mixed solution became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, the temperature was set at 28-30°C, and the material was waited for molding and curing for 48 hours to obtain an oxypropyl modified black liquor precipitate-based polyurethane sponge, which was recorded as OBLPPUF-20;

[0071] (5) Preparation of oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane (1 ml:40 ml) and stirred for 6 h, and then ultrasonically treated at 40 Kz for 10 min; the ultrasonicated material was rinsed with distilled water and n-hexane, and the excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45 °C for 12 h to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, which was recorded as OTS-OBLPPUF-20.

[0072] Example 5

[0073] 25wt% oxypropylated cotton black liquid-based polyurethane oil-water separation sponge:

[0074] (1) Preparing a cotton spinning black liquor extract: mixing cotton spinning black liquor with anhydrous ethanol in a mass ratio of 1:3, stirring thoroughly and then standing for 6 hours, then taking the supernatant and evaporating and drying it to obtain a cotton spinning black liquor extract;

[0075] (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to cyclopentane for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the cyclopentane, thereby obtaining the organic matter in the cotton spinning black liquor;

[0076] (3) Preparation of oxypropylated cotton spinning black liquor extract:

[0077] 20 g of organic matter in cotton spinning black liquor was added to a high-pressure reactor, and then 20 g of propylene oxide, 1 g of potassium hydroxide and 40 g of acetone were added to the reactor, and then 5 g of anhydrous glycerol was added to the reactor, and the reaction was carried out at 150° C. for 2 h, while the reactor was kept in a high pressure state (3 atmospheres) and stirred at a speed of 400 rpm to obtain an oxypropyl-modified cotton spinning black liquor extract, which was recorded as OBLP;

[0078] (4) Preparation of oxypropyl modified black liquor precipitate based polyurethane sponge:

[0079] 30 parts of high resilience polyether alcohol, 10 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution and 0.45 parts of silicone oil surfactant were mixed, and vigorously stirred at 1000 rpm for 30 seconds, and then 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate were added, and stirring was continued until the mixed solution became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, the temperature was set at 28-30°C, and the material was waited for molding and curing for 48 hours to obtain an oxypropyl modified black liquor precipitate-based polyurethane sponge, which was recorded as OBLPPUF-25;

[0080] (5) Preparation of oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane (1 ml:40 ml) and stirred for 6 h, and then ultrasonically treated at 40 Kz for 10 min; the ultrasonicated material was rinsed with distilled water and n-hexane, and the excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45 °C for 12 h to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, which was recorded as OTS-OBLPPUF-25.

[0081] Example 6

[0082] 30wt% oxypropylated cotton black liquid-based polyurethane oil-water separation sponge:

[0083] (1) Preparing a cotton spinning black liquor extract: mixing cotton spinning black liquor with anhydrous ethanol in a mass ratio of 1:3, stirring thoroughly and then standing for 6 hours, then taking the supernatant and evaporating and drying it to obtain a cotton spinning black liquor extract;

[0084] (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to cyclopentane for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the cyclopentane, thereby obtaining the organic matter in the cotton spinning black liquor;

[0085] (3) Preparation of oxypropylated cotton spinning black liquor extract:

[0086] 20 g of organic matter in cotton spinning black liquor was added to a high-pressure reactor, and then 20 g of propylene oxide, 1 g of potassium hydroxide and 40 g of acetone were added to the reactor, and then 5 g of anhydrous glycerol was added to the reactor, and the reaction was carried out at 150° C. for 2 h, while the reactor was kept in a high pressure state (3 atmospheres) and stirred at a speed of 400 rpm to obtain an oxypropyl-modified cotton spinning black liquor extract, which was recorded as OBLP;

[0087] (4) Preparation of oxypropyl modified black liquor precipitate based polyurethane sponge:

[0088] 28 parts of high resilience polyether alcohol, 12 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution and 0.45 parts of silicone oil surfactant were mixed, and vigorously stirred at 1000 rpm for 30 seconds, and then 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate were added, and stirring was continued until the mixed solution became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, the temperature was set at 28-30°C, and the material was waited for molding and curing for 48 hours to obtain an oxypropyl modified black liquor precipitate-based polyurethane sponge, which was recorded as OBLPPUF-30;

[0089] (5) Preparation of oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane (1 ml:40 ml) and stirred for 6 h, and then ultrasonically treated at 40 Kz for 10 min; the ultrasonicated material was rinsed with distilled water and n-hexane, and the excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45 °C for 12 h to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, which was recorded as OTS-OBLPPUF-30.

[0090] Experimental Example 1 Calculation of the yield of organic matter extracted from oils and fats by organic solvents

[0091] The organic solvent extraction method is used to separate the oily organic matter in the cotton spinning black liquor, and then the extracted organic matter is subjected to rotary evaporation treatment using a rotary evaporator to remove the polar solvent. The yield of the organic matter is calculated using Formula 1.

[0092]

[0093] The parameters in the formula are as follows: m 有机质 is the organic matter content in the extract, g; m 前 is the mass of organic matter in the residual liquid before extraction, g; m 后 is the mass of organic matter in the residual liquid after extraction, g; W 萃取 is the extraction yield, %.

[0094] Table 1 The yield of oil and wax in cotton spinning black liquor extracted by different organic solvents

[0095]

[0096] Since the cotton spinning black liquor is relatively viscous, and the container wall that has been filled with cotton spinning black liquor is difficult to be directly rinsed with clean water, it is necessary to add degreasing detergent to thoroughly clean it. After centrifugation at 5000rpm for 3min, it was found that the cotton spinning black liquor in the centrifuge tube was three layers: the upper layer was a relatively viscous waxy semi-solid, the middle layer was a fluid liquid, and the bottom layer was a solid close to the tube wall. The three-layer separation phenomenon of cotton spinning black liquor after centrifugation shows that the liquid contains organic substances in different states. After analysis, it can be roughly judged that the analysis of the top layer of substances after centrifugation is mainly grease and wax, which may be due to the low solubility of these substances in the solution, so they exist in a semi-solid form. Based on this experimental result, the cotton spinning black liquor is extracted by using different organic solvents to separate the top layer of organic matter. The yield data show that different solvents have different extraction effects on organic matter in cotton spinning black liquor. The yield of cyclopentane is the highest, which is 1.7%, followed by n-hexane, with a yield of 0.86%, while the yields of ethyl acetate, acetone and n-propanol are relatively low, which are 0.48%, 0.46% and 0.41% respectively. These data show that different organic solvents have different extraction effects on organic matter in cotton spinning black liquor, which may be due to the different affinity between different solvents and organic matter in cotton spinning black liquor, resulting in differences in solubility and separation effect of organic matter in solution. Therefore, cyclopentane is used in the embodiment of the present invention to extract the cotton spinning black liquor extract.

[0097] Test Example 2 Characterization of Apparent Density of Sponge

[0098] The apparent density of the prepared sponge was tested for the products prepared in Examples 1-6 according to GB / T 6343-2009 "Determination of the apparent density of foamed plastics". The specific method is as follows: Use a knife to take out the polyurethane sponge from the plastic tube after curing at room temperature for 48 hours, cut a section of cylindrical sponge with a thickness of about 1 to 1.5 cm at the place where the foaming is relatively uniform, and use a vernier caliper to measure its diameter and height respectively, and calculate the average value after measuring three times; weigh the sample mass, and calculate the average value after weighing three times. Calculate its volume, and calculate the apparent density of the lignin-based polyurethane sponge by the mass-to-volume ratio.

[0099] Microscopic surface observation of polyurethane sponges with different replacement amounts of oxypropylated black liquor extracts was performed. Figure 1 As shown in the figure. The pores on the surface of the sponge are neatly arranged and the pore sizes are relatively consistent. Although some closed pores still exist, the sponge as a whole presents a through-pore structure and has a relatively low density. This may be due to the increase in the viscosity of the reaction system caused by the addition of the black liquor extract modified by oxypropylation, and the reaction of isocyanate with water to generate CO 2The speed is extremely fast, but the polyol and isocyanate are not in sufficient contact, resulting in the formation of closed cells. In addition, the reaction system is small, the amount of each component is small, but the reaction speed is fast, it is difficult to accurately grasp the proportion of each component, or the cross-linking degree is large, the cross-linking speed is too fast, and the use of too many amines and physical foaming agents leads to low internal pressure of the foam, which will also make it difficult to open holes in the polyurethane sponge. In addition, a too large TDI index may also be one of the reasons for closed cells. It is worth noting that as the amount of modified extract added increases, the number of closed cells in the foam also increases.

[0100] On this basis, the apparent density of polyurethane sponges with different substitution amounts was measured and calculated. The results are as follows: Figure 2 Generally speaking, the density of soft sponges is mainly divided into three ranges: low density, medium density and high density. The density of low-density sponges is usually 0.1-0.3g / cm 3 The density of medium density sponge is between 0.3-0.5g / cm 3 The density of high-density sponge is between 0.5-1.0g / cm 3 The density of OBLPPUF-5, OBLPPUF-10, OBLPPUF-15 and OBLPPUF-20 is mainly concentrated in 0.1-0.3g / cm 3 It is a low-density sponge, while the density of OBLPPUF-25 and OBLPPUF-30 is 0.3-0.5g / cm 3 The density of OBLPPUF is within the range of 1.5-2.0, which belongs to medium-density sponge. Sponges of different densities have different characteristics and applications. Medium and low-density sponges usually have good water absorption and air permeability, and are suitable for making face towels, wiping cloths and other cleaning products or protective materials for goods. This superior density range broadens the application field of OBLPPUF.

[0101] Test Example 3 Characterization of the compressive strength of sponge

[0102] The mechanical properties were characterized by compression tests using a universal testing machine (UTM2203, Shenzhen Sun Technology Co., Ltd., China) with a 100N load cell. Cylindrical samples with a diameter of 11 mm and a height of 10 mm were compressed to a compressive strain of 80% at a rate of 80 mm min-1. The compressive strength was calculated as shown in Equation 2:

[0103]

[0104] where P is the stress corresponding to 80% strain and S is the original cross-sectional area of ​​the sample.

[0105] Although the prepared sponge has a good density, combined with the porosity and hardness of the sponge, when the replacement amount is greater than 25%, too many closed pores lead to a decrease in the water absorption rate of the sponge. At the same time, by squeezing the sponge by hand, it was found that the elastic effect of the sponge was significantly reduced. Therefore, a compression test was conducted to measure the compression and rebound effects of sponges with different replacement amounts. The specific results are shown in Figure 3 .

[0106] The experimental results show that sponges with different substitution amounts have a certain resilience. Among them, OBLPPUF-5 and OBLPPUF-10 have better elasticity, while OBLPPUF-15 has the best elasticity. However, with the increase of the amount of modified cotton spinning black liquor extract added, the elasticity of the sponge gradually weakened. From the perspective of the compressive strength of the sponge, the maximum compressive strength of OBLPPUF-5 to OBLPPUF-15 gradually decreased, with the lowest being about 8.6MPa, which can be almost easily compressed. Subsequently, with the increase of the amount of oxypropylated cotton spinning black liquor extract added, the compressive strength of the sponge also gradually increased, and OBLPPUF-30 had the highest compressive strength, which could reach 1980MPa. Therefore, replacing polyols with oxypropylated cotton spinning black liquor extract can change the flexibility of the sponge. When the substitution amount is low, the sponge becomes soft and easy to compress and rebound, but when the substitution amount is further increased, the sponge gradually becomes hard, no longer soft, and difficult to compress and rebound. It is worth noting that the error in the distribution ratio of each group in the production process of polyurethane sponge may also be one of the factors affecting the compression resilience of the sponge.

[0107] Test Example 4 Characterization of thermal stability of sponge

[0108] The thermal stability of RPF was determined by METTLER TGA / DSC simultaneous thermal analysis. About 10 mg of sample was weighed before the test, and the test conditions were a temperature increase range from 40°C to 800°C, a heating rate of 10°C / min, and N 2 atmosphere, with a flow rate of 50.0 mL / min.

[0109] Table 2 GPC data of cotton spinning black liquor extract before and after oxypropyl modification

[0110]

[0111] As shown in Table 2. As a result, the polyurethane sponge prepared by using oxypropylated cotton spinning black liquor extract as a substitute exhibited good thermal stability.

[0112] Test Example 5 Measurement of water contact angle of sponge

[0113] Cut the sponge into blocks or sheets with smooth surfaces and do not need further processing for testing. The surface water contact angle was measured by DSA25 contact angle tester. Each sample was tested 5 times and the final result was taken as the arithmetic average. The test temperature was room temperature 25℃ and the droplet volume was 2μL.

[0114] The absorption of oil and water was observed by dropping them on the sponge surface (see Figure 4 ), it can be found that after soybean oil is dripped onto the surface of the sponge, the oil quickly penetrates into the sponge, is absorbed, and leaves a circular yellow oil mark on the surface. When water is dripped into it again, due to the excellent hydrophobic properties of the sponge, water cannot penetrate into the sponge, but floats on the surface of the sponge to form elliptical water droplets, which is in sharp contrast to the soybean oil. Through compression testing, it is found that the sponge floats in water, and a silver mirror effect is produced on the surface, showing obvious hydrophobicity. After the oil red dye is dripped into the water, the oil around the sponge is quickly absorbed, forming an area without red oil, and the surface of the sponge is dyed red, proving that the cotton spinning black liquor extract-based polyurethane oil-absorbing sponge has oleophilic and hydrophobic properties and can be used for oil-water separation.

[0115] Water contact angle test of polyurethane oil-absorbing sponge with different substitution amounts (see Figure 5 ), the results show that the water contact angle of OTS-OBLPPUF increases with the increase of substitution amount. The water contact angle of OTS-OBLPPUF-0 without modified extract is the smallest, which is 117.75°, while when the substitution amount is 30wt%, the water contact angle of the sponge is the largest, which is 137.75°. This shows that with the addition of oxypropylated cotton spinning black liquor extract, the surface hydrophobicity of the sponge is enhanced. The main reasons include the formation of a dense film of OTS on the outer layer of the sponge, which makes the surface of the sponge hydrophobic, as well as the increase in the viscosity of the reaction system, the change in the degree of crosslinking and other factors, which together increase the surface energy of the sponge and obtain a hydrophobic effect.

[0116] Although the hydrophobicity of the sponge has changed, its three-dimensional pore structure is not affected and still has the capillary adsorption effect of liquid, making the sponge hydrophobic while still being able to be repeatedly squeezed to recover oil. Overall, the modified sponge has potential application prospects in the field of oil-water separation.

[0117] Test Example 6 Maximum Oil Adsorption Test

[0118] The maximum adsorption capacity of the modified sponge for various oils was tested by the following method: first, a modified sponge with a mass of m0 was immersed in the oil, taken out after saturation adsorption, and placed on a steel wire mesh for 30 seconds to remove the oil attached to the surface, and then weighed on a precision analytical balance, recorded as m. The maximum adsorption capacity E of the modified sponge was calculated by formula 34.

[0119]

[0120] Among them, M 0is the initial mass of the sponge, and M is the mass of the sponge when it reaches the maximum adsorption capacity in the oil.

[0121] Figure 6 The trend of the maximum oil adsorption rate of each sponge is shown. The experimental results show that biomass polyurethane sponges generally show excellent oil adsorption effects, and the polyol substitution rate of oxypropylated cotton spinning black liquor has a certain effect on the oil absorption rate of the sponge. Specifically, the maximum oil adsorption rates of the three groups of sponges, OTS-OBLPPUF-5, OTS-OBLPPUF-10 and OTS-OBLPPUF-15, showed a gradual upward trend, all greater than 2500%, among which OTS-OBLPPUF-15 had the largest oil adsorption rate of 2791.8%. However, with the increase in the amount of oxypropylated cotton spinning black liquor substitution, the oil absorption effect of the sponge showed a linear downward trend until OTS-OBLPPUF-30 with the smallest oil adsorption rate was 371.5%, which was lower than 500%.

[0122] Test Example 7: Repeated use performance test

[0123] The recycling performance of the material is obtained through a cyclic process of absorption and centrifugation. The specific operation is as follows: first take a piece of sponge, weigh and record its weight, immerse it in oil until saturation adsorption is reached. Then take it out, place it on a wire filter for 30 seconds, and then weigh it on a precision balance and record it. Then the sponge is centrifuged at a speed of 2500r / min for 3min to remove the oil or organic solvent adsorbed in the sponge pores, and then the above process is repeated.

[0124] In order to verify the repeated oil absorption performance of polyurethane sponge, five cycles of oil absorption experiments were carried out. Figure 7As shown in the figure, the oil absorption effect of OTS-OBLPPUF-5, OTS-OBLPPUF-10, OTS-OBLPPUF-15, OTS-OBLPPUF-20, OTS-OBLPPUF-25, and OTS-OBLPPUF-30 in the five-cycle experiment was almost unchanged compared with the first oil absorption. However, after 5 experiments, OTS-OBLPPUF-25 and OTS-OBLPPUF-30 were damaged after five repeated oil absorption and centrifugation. This may be because the cotton spinning black liquor precipitate extracted with ethanol, after oxypropylation modification, not only has hydroxyl groups that can be cross-linked with isocyanate, but also contains undecomposed dissolved cellulose, hemicellulose, wax, oil and pectin, as well as the decomposition products of these substances, such as various oligosaccharides, fatty acid salts, fatty alcohols, etc. These substances are wrapped in the sponge, and can increase the performance strength and mechanical properties of the sponge at a certain addition amount, but when the addition amount exceeds a certain range, it may have a negative impact on the sponge, such as reduced strength, increased hardness or easy breakage. Therefore, the experiment proves that when the replacement amount of oxypropylated cotton spinning black liquor extract is 15%, its polyurethane sponge has the best mechanical properties and repeated oil absorption performance.

[0125] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing an oxypropylated cotton spinning black liquid-based polyurethane oil-water separation sponge, characterized in that: The following steps are involved: (1) Preparing a cotton spinning black liquor extract: mixing the cotton spinning black liquor with anhydrous ethanol, stirring the mixture thoroughly and then standing the mixture for 6 hours, then taking the supernatant and evaporating and drying the mixture to obtain a cotton spinning black liquor extract; (2) extracting organic matter from the cotton spinning black liquor extract: adding the cotton spinning black liquor extract to an organic solvent for extraction, and performing a rotary evaporation treatment on the extracted solution to remove the organic solvent, thereby obtaining the organic matter in the cotton spinning black liquor; (3) Preparation of oxypropylated cotton spinning black liquor extract: The organic matter in the cotton spinning black liquor is added to a high-pressure reactor, and then propylene oxide, potassium hydroxide and acetone are added to the reactor, and then anhydrous glycerin is added. During the reaction, the reactor is kept in a high-pressure state and stirred to obtain an oxypropyl-modified cotton spinning black liquor extract, which is recorded as OBLP; the mass ratio of the organic matter, propylene oxide, potassium hydroxide, acetone and anhydrous glycerin in the cotton spinning black liquor is 10-30:10-30:1-3:30-50:3-10; (4) Preparation of oxypropyl modified black liquor extract-based polyurethane sponge: High resilience polyether alcohol, OBLP, dichloromethane, water, 33% triethylenediamine solution and silicone oil surfactant were mixed, and the mixture was vigorously stirred at 1000rpm for 30s, and then toluene diisocyanate and stannous octoate were added, and stirring was continued until the mixture became turbid due to the appearance of fine bubbles, the bubbles began to rise, and the volume gradually expanded; the mixture was placed in an oven, and the material was cured after being formed to obtain an oxypropyl modified black liquor precipitate-based polyurethane sponge, which was recorded as OBLPPUF; the following raw materials were used in the preparation of OBLPPUF in parts by weight: 28-38 parts of high resilience polyether alcohol, 2-12 parts of OBLP, 1.48 parts of dichloromethane, 2.2 parts of water, 0.06 parts of 33% triethylenediamine solution, 0.45 parts of silicone oil surfactant, 19.23 parts of toluene diisocyanate and 0.07 parts of stannous octoate; (5) Preparation of an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge: OBLPPUF was immersed in a mixed solution of trichloro(octadecyl)silane and n-hexane, stirred for 6 hours, and then ultrasonically treated; the ultrasonicated material was rinsed with distilled water and n-hexane, respectively, and excess liquid on the sponge surface was squeezed out after rinsing, and dried at 45°C to 50°C for 8 to 12 hours to obtain an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge, denoted as OTS-OBLPPUF; the volume ratio of trichloro(octadecyl)silane to n-hexane in the mixed solution of trichloro(octadecyl)silane and n-hexane was 1:

40.

2. The method for preparing an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge according to claim 1, characterized in that: The mass ratio of the cotton spinning black liquor to anhydrous ethanol in step (1) is 1:3 to 1:

5.

3. The method for preparing an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge according to claim 1, characterized in that: The organic solvent in step (2) is any one of n-hexane, cyclopentane, ethyl acetate, acetone and n-propanol.

4. The method for preparing an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge according to claim 1, characterized in that: In step (3), the reaction temperature is 120-180° C., the reaction time is 1.5-3 h, and the stirring rate is 300-500 rpm.

5. The method for preparing an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge according to claim 1, characterized in that: The oven temperature in step (4) is 28-30° C., and the molding and curing time is 48 hours.

6. The method for preparing an oxypropylated cotton black liquid-based polyurethane oil-water separation sponge according to claim 1, characterized in that: The ultrasonic power in step (5) is 40 Hz, and the ultrasonic time is 10 to 15 minutes.

7. An oxypropylated cotton spinning black liquid-based polyurethane oil-water separation sponge, characterized in that: The method is prepared by any one of claims 1 to 6.

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