Apparatus and method for continuous removal of solvent from aqueous polyurethane emulsion

Abstract

The application provides a device and method for continuous removal of solvent from water-based polyurethane emulsion, the device comprises a desolventizing tower, a cooling device and a vacuum device connected in sequence; a heating device is arranged outside the desolventizing tower; a plurality of trays are arranged in the desolventizing tower, one end of the tray is fixed to the inner wall of the desolventizing tower, and the other end is provided with an overflow weir. The device and method provided by the application effectively solve the problems of low efficiency, high vacuum degree, easy skinning, slagging, foaming and heater blocking in the traditional solvent removal process of water-based polyurethane emulsion; the organic solvent in the water-based polyurethane emulsion can be automatically, efficiently and quickly removed continuously, the water content in the organic solvent is low, and the organic solvent can be used for subsequent production without the need for separation and purification through a refining system again.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waterborne polyurethane emulsion solvent removal, and particularly relates to a device and method for continuous removal of solvent from waterborne polyurethane emulsion. BACKGROUND

[0002] Waterborne polyurethane emulsion is a low odor, non-toxic, green and environmentally friendly organic polymer material, which is obtained by replacing organic solvent with water as the dispersion medium through certain technical means and contains a small amount of volatile organic solvent (VOC). In the use process, the dispersion medium water is volatilized to form a polyurethane film, so that the film-forming material of the waterborne polyurethane emulsion has the same excellent physical and chemical properties as the polyurethane material. Waterborne polyurethane material can be obtained by adjusting the formula and chemical modification method to obtain high-performance materials with different hardness, different chemical resistance, and is widely used in wood coatings, textile coatings, synthetic leather, plastic coatings, metal coatings, personal care, coating agents, adhesives, sealants, water-based inks and other fields.

[0003] At present, the production process of waterborne polyurethane emulsion for removing organic solvents in the industry is mainly intermittent. The intermittent process refers to a process in which pre-polymerization, chain extension, dispersion, and solvent removal are carried out in the reaction kettle in time sequence after one-time feeding. However, the intermittent removal process has significant disadvantages in the production of waterborne polyurethane emulsion, such as low production efficiency, high idle rate of devices, high production cost, low degree of automation, large quality fluctuation between batches, and high rate of defective products.

[0004] Especially, the removal of acetone solvent in the current industry still mainly adopts kettle intermittent desolventization, which has the problems of long time consumption, low efficiency, high vacuum degree, easy skinning, slagging, foaming, and heater blocking. The residual organic solvents such as acetone after the treatment of the waterborne polyurethane emulsion desolventization process in the current industry are still at a high level (about 500-3000 ppm). In addition, the acetone solvent obtained by removal contains a high content of water, which cannot be directly used for production, and still needs a set of acetone solvent refining system, resulting in large equipment investment and high operation cost.

[0005] CN110193312A discloses a kind of water-based polyurethane efficient desolventizing equipment, including heat preservation layer, the heat preservation layer includes vacuum layer, glassed microsphere heat preservation sand layer and XPS polyurethane foam layer, vacuum layer is arranged in the inside of glassed microsphere heat preservation sand layer, the side of vacuum layer away from glassed microsphere heat preservation sand layer is provided with XPS polyurethane foam layer, the inside of heat preservation layer is provided with desolventizing kettle body, the inside middle position of desolventizing kettle body is provided with stirring shaft, three stirring rods are uniformly arranged in the below of stirring shaft, four stirring blades are arranged on each stirring rod, and solvent is removed by strong stirring.But this method is easy to bubble in the stirring process, a large amount of skin is produced in kettle wall, needs to stop cleaning, simultaneously cannot continuous production, affect the production efficiency of equipment.

[0006] In summary, provide a kind of water-based polyurethane emulsion desolventizing device and method of high efficiency energy saving, degree of automation is high, continuous production and product yield is high, is the urgent problem of person skilled in the art. SUMMARY

[0007] The purpose of the present application is to provide a water-based polyurethane emulsion continuous desolventizing device and method, which can automatically, efficiently and quickly continuously remove organic solvents from water-based polyurethane emulsion while removing low water content in organic solvents, without the need for further separation and purification by a refining system for subsequent production.

[0008] To achieve this invention purpose, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a water-based polyurethane emulsion continuous desolventizing device, which comprises a desolventizing tower, a cooling device and a vacuum device connected in sequence.

[0010] The desolventizing tower is provided with a heating device outside.

[0011] The desolventizing tower is provided with a plurality of trays inside, one end of the tray is fixed to the inner wall of the desolventizing tower, and the other end is provided with an overflow weir.

[0012] In the present application, the top of the desolventizing tower is connected with a cooling device; the vacuum device comprises a vacuum pump and an auxiliary device, and the tower top pressure of the desolventizing tower is adjusted by the vacuum device according to actual needs; the desolventizing tower kettle is provided with a heating device outside.

[0013] The device provided by the application adopts a specific structure of the tray and is provided with a heating device outside the tank of the desolventizing tower, is sequentially connected with a cooling device and a vacuum device, and has the functions of emulsion desolventizing and organic solvent refining, effectively solves the problems of low efficiency, high vacuum degree, easy skinning, slagging, foaming and heater blocking in the process of removing the solvent from the traditional water-based polyurethane emulsion, realizes automatic, rapid and efficient continuous removal of the solvent in the water-based polyurethane emulsion, reduces the removal energy consumption, has less loss of the organic solvent in the removal process, and has stable product quality of the water-based polyurethane emulsion and low water content in the removed organic solvent.

[0014] As a preferred technical solution of the application, the side wall of the desolventizing tower is provided with a feeding port.

[0015] Preferably, the bottom of the desolventizing tower is provided with a product discharge port.

[0016] As a preferred technical solution of the application, the side wall of the desolventizing tower is provided with a gas inlet.

[0017] In the application, the gas introduced through the gas inlet includes any one or a combination of at least two of nitrogen, carbon dioxide, air or oxygen, and is preferably nitrogen; the introduction of nitrogen can also avoid the generation of an explosive atmosphere.

[0018] Preferably, the desolventizing tower tank is provided with a distribution device, and the distribution device is arranged at 5%-50% of the liquid holding height in the desolventizing tower tank, for example, at 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45% and the like, but is not limited to the listed values, and other values within the value range are also applicable, and preferably at 10%-20%.

[0019] In the application, the distribution device is used for uniform dispersion of the gas introduced into the desolventizing tower, which can improve the desolventizing efficiency by gas stripping, and is also conducive to system pressure regulation and stability under different operating conditions.

[0020] In the application, the distribution device is horizontally arranged in the tank of the desolventizing tower and has a certain height from the bottom of the desolventizing tower, specifically at 5%-50% of the liquid holding height in the tank of the desolventizing tower, which is conducive to the uniform dispersion and role of the gas in the desolventizing tower. The liquid holding height is the liquid level height reached by the water-based polyurethane emulsion in the tank of the desolventizing tower.

[0021] Preferably, the distribution device is in communication with the pipeline of the gas inlet.

[0022] As a preferred technical solution of the application, the inner wall of the desolventizing tower is alternately provided with a plurality of trays from left to right, and the trays are all arranged below the feeding port.

[0023] In the present application, the left-right alternation is specifically that the adjacent trays are arranged alternately left and right on the inner wall of the desolventizing tower. The trays are all arranged above the distribution device.

[0024] Preferably, the ratio of the diameter of the tray to the desolventizing tower is (0.85-0.92):1, for example, it can be 0.86:1, 0.87:1, 0.88:1, 0.89:1, 0.9:1 or 0.91:1, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0025] Preferably, the distance between adjacent trays is 200-700mm, for example, it can be 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm or 650mm, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 400-600mm.

[0026] In the present application, the distance between adjacent trays needs to be controlled. If the distance between adjacent trays is too small, entrainment of mist is caused. If the distance between adjacent trays is too large, foaming is easily caused, and too large flow rate also causes demulsification, affecting product quality.

[0027] Preferably, the number of trays is 3-15, for example, it can be 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 6-10.

[0028] In the present application, the number of trays needs to be controlled. If too many trays are arranged, high production energy consumption and too much liquid storage in the desolventizing tower are caused. If too few trays are arranged, insufficient desolventizing efficiency and too much solvent storage in the desolventizing tower are caused.

[0029] As a preferred technical solution of the present application, a plurality of holes are formed on the tray.

[0030] Preferably, the hole diameter of the hole is 2-20mm, for example, it can be 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm or 19mm, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 3-10mm.

[0031] In the present application, the hole diameter of the hole needs to be controlled. If the hole diameter of the hole is too large, liquid leakage is caused, which is not conducive to the formation of a good liquid film. If the hole diameter of the hole is too small, emulsion foaming and entrainment of mist are caused due to too fast gas speed.

[0032] Preferably, the shape of the hole includes a round hole and / or a square, preferably a round hole.

[0033] Preferably, the opening rate of the tray is 3-30%, for example, it can be 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25% or 28%, etc., but not limited to the listed values, other values not listed in the value range are also applicable, preferably 10-20%.

[0034] In the present application, by controlling the opening rate of the tray in the range of 3-30%, good film forming property and desolventization efficiency are ensured.

[0035] Preferably, the tray is vertically arranged with the overflow weir.

[0036] Preferably, the height of the overflow weir is 5-50mm, for example, it can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm or 45mm, etc., but not limited to the listed values, other values not listed in the value range are also applicable, preferably 10-30mm.

[0037] In the present application, by arranging the overflow weir at one end of the tray, the emulsion is ensured to have good film forming, and the solvent is efficiently separated; in addition, the height of the overflow weir needs to be controlled, if the height of the overflow weir is too low, the separation efficiency of the desolventization tower is low; if the height of the overflow weir is too high, liquid leakage and excessive pressure drop of the tower will occur, which is not conducive to desolventization.

[0038] As a preferred technical solution of the present application, the heating device comprises a heat preservation jacket.

[0039] In the present application, a heating device is arranged outside the tower kettle of the desolventization tower, which can reduce the operating cost on the one hand, and can avoid problems such as emulsion skinning and particle size increasing, thereby avoiding affecting the product quality.

[0040] In the present application, the heat medium in the heat preservation jacket comprises hot water or steam, preferably hot water. By controlling the flow rate of the heat medium, the material temperature of the tower kettle of the desolventization tower is controlled.

[0041] Preferably, the outlet of the cooling device is connected with an organic solvent storage tank.

[0042] Secondly, the present application provides a method for continuously removing solvent from water-based polyurethane emulsion, which uses the device of the first aspect, and comprises the following steps:

[0043] (1) The water-based polyurethane emulsion crude product is transported into the desolventization tower through the feed inlet, and the water-based polyurethane emulsion crude product is distributed on the tray to form a film, and at the same time, flash separation is carried out to obtain a flash gas phase and a flash liquid phase;

[0044] (2) The flash vapor phase of step (1) is led out to a cooling device by a vacuum device, and the organic solvent is collected after being condensed by the cooling device; the flash liquid phase of step (1) is sequentially removed downward by the tray, and the water-based polyurethane emulsion product is obtained from the tower kettle of the desolventizing tower.

[0045] In the present application, a certain liquid level of the water-based polyurethane emulsion crude product can be introduced into the tower kettle of the desolventizing tower in advance.

[0046] The method provided by the present application can automatically, efficiently and quickly continuously remove the organic solvent in the water-based polyurethane emulsion, and the water content in the organic solvent is low, so that the subsequent production can be used without further separation and purification by a refining system.

[0047] As a preferred technical solution of the present application, the organic solvent in the water-based polyurethane emulsion crude product of step (1) includes acetone.

[0048] In the present application, the water-based polyurethane emulsion crude product includes water-based polyurethane dispersion (PUD) crude product and / or water-based polyurethane / acrylate composite emulsion (PUA) crude product; the water-based polyurethane emulsion crude product is prepared by reacting isocyanate with polyol and hydrophilic chain extender in an organic solvent environment.

[0049] In the present application, the isocyanate includes any one or a combination of at least two of dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI) or toluene diisocyanate (TDI), preferably dicyclohexylmethane diisocyanate and / or hexamethylene diisocyanate; the polyol includes any one or a combination of at least two of polybutylene adipate glycol (PBA-2000), polyneopentyl glycol adipate glycol and polyhexanediol adipate copolymer (CMA654) or polycaprolactone glycol (CAPA2209), preferably polybutylene adipate glycol; the chain extender includes any one or a combination of at least two of 2,2-dimethylol propionic acid (DMPA), 1,4-butanediol (BDO), sodium ethylenediamine sulfonate (A95), isophorone diamine (IPDA), hydroxyethyl ethylenediamine or polyethylene glycol monomethyl ether (MPEG1200), preferably any one or a combination of at least two of 2,2-dimethylol propionic acid, isophorone diamine, hydroxyethyl ethylenediamine or polyethylene glycol monomethyl ether.

[0050] As a preferred technical solution of the present application, step (1) further includes: adjusting the tower kettle temperature of the desolventizing tower by a heating device, adjusting the tower top pressure of the desolventizing tower by a vacuum device, and then opening the gas inlet.

[0051] Preferably, the temperature of the kettle of the desolventizing tower is 35-45℃, for example, it can be 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃ or 44℃, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0052] Preferably, the top pressure of the desolventizing tower is 30-80kPa, for example, it can be 35kPa, 40kPa, 45kPa, 50kPa, 55kPa, 60kPa, 65kPa, 70kPa or 75kPa, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 40-55kPa.

[0053] As a preferred technical solution of the present application, the temperature of the cooling medium in the cooling device of step (2) is -5-15℃, for example, it can be -4℃, -3℃, -2℃, -1℃, 0℃, 1℃, 2℃, 3℃, 5℃, 6℃, 8℃ or 9℃, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable, preferably 0-5℃.

[0054] In the present application, the cooling medium includes water and / or ethylene glycol; the amount of the cooling medium is adjusted according to the temperature of the gas phase in the cooling device.

[0055] Preferably, the water content in the organic solvent of step (2) is <100ppm, for example, it can be 90ppm, 80ppm, 70ppm, 60ppm, 50ppm, 40ppm or 20ppm, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0056] Preferably, the organic solvent content in the aqueous polyurethane emulsion product of step (2) is <10ppm, for example, it can be 9ppm, 8ppm, 7ppm, 6ppm, 5ppm, 4ppm or 2ppm, etc., but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0057] Compared with the prior art, the present application has the following beneficial effects:

[0058] (1) The device provided by the application adopts a specific structure of the tray and is provided with a heating device outside the tower kettle of the desolventizing tower, is sequentially connected with a cooling device and a vacuum device, realizes stable and efficient removal of the organic solvent in the desolventizing tower by using emulsion film formation, and the emulsion is stable and not easy to foam, without the need of additional defoaming agent, and under the preferred condition, the residual organic solvent in the emulsion is reduced to below 10 ppm, realizing the green environmental protection of the product, and at the same time, the function of the organic solvent refining is realized, and under the preferred condition, the water content in the organic solvent is as low as below 100 ppm, which can be used for subsequent production without the need of separation and purification through the refining system again, greatly saving the equipment investment cost and operation cost.

[0059] (2) The device and method provided by the application effectively solve the problems of low efficiency, high vacuum degree, easy skinning, slagging, foaming and heater blocking in the traditional waterborne polyurethane emulsion solvent removal process, realize rapid, efficient, continuous, automatic and stable desolventizing, the emulsion product quality is stable, the desolventizing efficiency is improved, and the removal energy consumption and operation cost are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 The structure schematic view of the waterborne polyurethane emulsion continuous desolventizing device provided for the embodiment 1 is shown in the figure.

[0061] Figure 2 The structure schematic view of the hole on the tray in the embodiment 1 is shown in the figure.

[0062] In the figure, 1 is a feeding port, 2 is a tray, 3 is a desolventizing tower, 4 is a heating device, 5 is a distribution device, 6 is a product discharge port, 7 is an air inlet, 8 is an organic solvent storage tank, 9 is a cooling device, and 10 is a vacuum device. DETAILED DESCRIPTION

[0063] It should be understood that, in the description of the application, the orientation or positional relationship indicated by the terms “center”, “longitudinal”, “transverse”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the terms “first”, “second” and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by “first”, “second” and the like can explicitly or implicitly include one or more of the features. In the description of the application, unless otherwise stated, the meaning of “a plurality of” is two or more.

[0064] It should be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "arrangement", "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0065] The technical solutions of the present application will be further illustrated below by combining the drawings and through specific embodiments.

[0066] The preparation method of the water-based polyurethane emulsion provided in the specific embodiment of the present application comprises the following steps: first, the synthesis kettle is warmed to 60℃, then polybutylene adipate glycol, dicyclohexyl methane diisocyanate, hexamethylene diisocyanate, 2,2-dimethylol propionic acid, polyethylene glycol monomethyl ether and acetone are proportionally put into the synthesis kettle, then the stirring is started, the stirring speed is 200 rpm / min, the temperature is warmed to 85-90℃, and the reaction is carried out for 3h, when the content of NCO% (isocyanate group) is 2.10%, the temperature is cooled to 50℃, and acetone is added for dilution, then the chain extender isophorone diamine and hydroxyethyl ethylenediamine are added, the stirring speed is increased to 1000 rpm / min, the temperature is kept at 40-45℃, and the reaction is carried out for 20 min, then water is gradually added and dispersed for 10 min, the particle size is measured by sampling, and the water-based polyurethane emulsion crude product is obtained, and the ratio of the synthesis raw materials is specifically limited according to the needs.

[0067] In the specific embodiment of the present application, the raw materials for synthesizing the water-based polyurethane emulsion are all commercially available products, and the water-based polyurethane emulsion crude product to be treated is all the same material.

[0068] In the specific embodiment of the present application, the test method of the content of acetone is as follows: 50g of sample is taken and analyzed by headspace sampling gas chromatography; the gas chromatograph is Agilent Technologies 7890B; the parameters are as follows: the type of chromatographic column is DB WAX (30m x 0.25mm x 0.25um); the temperature of the injection port is 200℃, the split ratio is 50:1, the pressure is 76.025psi, the septum purge flow is 3mL / min; the flow rate of the chromatographic column is 1mL / min and the flow rate is constant.

[0069] The method for testing the water content in the specific embodiment of the present application is as follows: 1 mL of sample is taken in a gas chromatography vial, and the water content is quantitatively tested by gas phase-TCD. The gas chromatograph model is Agilent 7890B, and the parameters are as follows: chromatographic column model: HP-PLOT / Q (30 m x 0.53 mm x 40 um), injection port temperature: 250 DEG C, injection volume: 0.5 mu L, split ratio: 10:1, column flow rate: 4 mL / min, constant flow mode, detector TCD, detector temperature: 270 DEG C.

[0070] In the following examples of the present application, the diameter ratio of the tray to the desolventizing tower is 0.9:1.

[0071] Example 1

[0072] The present embodiment provides a device for continuously removing solvent from an aqueous polyurethane emulsion (as shown in Figure 1 The device comprises a desolventizing tower 3, a cooling device 9 and a vacuum device 10 connected in sequence;

[0073] The side wall of the desolventizing tower 3 is provided with a feed inlet 1; the bottom of the desolventizing tower 3 is provided with a product discharge outlet 6;

[0074] The inner wall of the desolventizing tower 3 is alternately provided with 10 trays 2 (as shown in Figure 2 One end of the tray 2 is fixed to the inner wall of the desolventizing tower 3, and the other end is provided with an overflow weir; the tray 2 is vertically arranged with the overflow weir; the height of the overflow weir is 10 mm;

[0075] The trays 2 are all arranged below the feed inlet 1; the distance between adjacent trays 2 is 600 mm; the trays 2 are provided with holes; the hole diameter of the holes is 3 mm; the shape of the holes includes a round hole shape; the opening rate of the trays 2 is 20%;

[0076] The side wall of the desolventizing tower 3 is provided with a gas inlet 7; a distribution device 5 is horizontally arranged in the tower kettle of the desolventizing tower 3, and the distribution device 5 is arranged at 15% of the liquid holding height in the tower kettle of the desolventizing tower 3; the distribution device 5 is in communication with the pipeline of the gas inlet 7;

[0077] The tower kettle of the desolventizing tower 3 is provided with a heating device 4 outside;

[0078] The outlet of the cooling device 9 is connected with an organic solvent storage tank 8.

[0079] Example 2

[0080] The present embodiment provides a device for continuously removing solvent from an aqueous polyurethane emulsion, which comprises a desolventizing tower, a cooling device and a vacuum device connected in sequence;

[0081] The side wall of the desolventizing tower is provided with a feeding port; the bottom of the desolventizing tower is provided with a product discharge port;

[0082] The inner wall of the desolventizing tower is alternately provided with six trays from left to right, one end of the tray is fixed to the inner wall of the desolventizing tower, and the other end is provided with an overflow weir; the tray is vertically arranged with the overflow weir; the height of the overflow weir is 30mm;

[0083] The trays are all arranged below the feeding port; the distance between adjacent trays is 400mm; the tray is provided with a hole; the hole diameter of the hole is 10mm; the shape of the hole includes a round hole; the opening rate of the tray is 10%;

[0084] The side wall of the desolventizing tower is provided with a gas inlet; a distribution device is horizontally arranged in the desolventizing tower kettle, and the distribution device is arranged at 20% of the liquid holding height in the desolventizing tower kettle; the distribution device is in communication with the pipeline of the gas inlet;

[0085] The desolventizing tower kettle is provided with a heating device outside;

[0086] The outlet of the cooling device is connected with an organic solvent storage tank.

[0087] Example 3

[0088] The embodiment provides a device for continuous removal of solvent of water-based polyurethane emulsion, which comprises a desolventizing tower, a cooling device and a vacuum device connected in sequence;

[0089] The side wall of the desolventizing tower is provided with a feeding port; the bottom of the desolventizing tower is provided with a product discharge port;

[0090] The inner wall of the desolventizing tower is alternately provided with eight trays from left to right, one end of the tray is fixed to the inner wall of the desolventizing tower, and the other end is provided with an overflow weir; the tray is vertically arranged with the overflow weir; the height of the overflow weir is 20mm;

[0091] The trays are all arranged below the feeding port; the distance between adjacent trays is 500mm; the tray is provided with a hole; the hole diameter of the hole is 6mm; the shape of the hole includes a round hole; the opening rate of the tray is 15%;

[0092] The side wall of the desolventizing tower is provided with a gas inlet; a distribution device is horizontally arranged in the desolventizing tower kettle, and the distribution device is arranged at 10% of the liquid holding height in the desolventizing tower kettle; the distribution device is in communication with the pipeline of the gas inlet;

[0093] The desolventizing tower kettle is provided with a heating device outside;

[0094] The outlet of the cooling device is connected with an organic solvent storage tank.

[0095] Embodiment 4

[0096] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and further limits the heating device to a heat preservation jacket on the basis of embodiment 1.

[0097] Embodiment 5

[0098] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and the number of the trays is 2, and other conditions are the same as those in embodiment 1.

[0099] Embodiment 6

[0100] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and the number of the trays is 15, and other conditions are the same as those in embodiment 1.

[0101] Embodiment 7

[0102] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and the distance between adjacent trays is 100 mm, and other conditions are the same as those in embodiment 1.

[0103] Embodiment 8

[0104] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and the distance between adjacent trays is 700 mm, and other conditions are the same as those in embodiment 1.

[0105] Embodiment 9

[0106] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and the pore size of the holes is 1 mm, and other conditions are the same as those in embodiment 1.

[0107] Embodiment 10

[0108] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and the pore size of the holes is 20 mm, and other conditions are the same as those in embodiment 1.

[0109] Embodiment 11

[0110] The embodiment provides a device for continuously removing solvent from water-based polyurethane emulsion, and the height of the overflow weir is 5 mm, and other conditions are the same as those in embodiment 1.

[0111] Embodiment 12

[0112] The embodiment provides a device for continuous removal of solvents from a water-based polyurethane emulsion, which is identical to that in the embodiment 1 except that the height of the overflow weir is 60 mm.

[0113] Comparative example 1

[0114] The comparative example provides a device for removal of solvents from a water-based polyurethane emulsion, which adopts a general batch kettle type desolventizing device, the desolventizing kettle is provided with a stirring device, a product discharge port is arranged at the bottom of the desolventizing kettle, and a gas phase condensing system and a vacuum system are sequentially connected to the top of the desolventizing kettle, and the outlet of the gas phase condensing system is connected with an acetone storage tank.

[0115] Comparative example 2

[0116] The comparative example provides a device for removal of solvents from a water-based polyurethane emulsion, which is identical to that in the embodiment 1 except that the tray in the desolventizing tower is replaced by Sulzer Mellapak 202Y type structured packing.

[0117] Application examples 1-12

[0118] The application example provides a method for continuous removal of solvents from a water-based polyurethane emulsion, which is performed by using the device provided in the application examples 1-12, and comprises the following steps.

[0119] (1) the desolventizing tower is supplied with the water-based polyurethane emulsion crude product with a liquid holdup of 60%, the kettle temperature of the desolventizing tower is regulated to 40 DEG C by using a heating device, the tower top pressure of the desolventizing tower is regulated to 40 kPa by using a vacuum device, then the gas inlet is opened, and nitrogen is supplied;

[0120] (2) the water-based polyurethane emulsion crude product is conveyed into the desolventizing tower through a feeding port, the water-based polyurethane emulsion crude product is distributed in the form of film on the tray, and flash separation is performed at a temperature of 40 DEG C and a pressure of 40 kPa, so as to obtain a flash gas phase and a flash liquid phase;

[0121] (3) the flash gas phase in the step (2) is led out to a cooling device through a vacuum device, acetone is collected after being condensed by the cooling device, the liquid holdup in the desolventizing tower is ensured to be 60% by controlling the feeding flow rate of the feeding port, the flash liquid phase in the step (2) is sequentially downwardly passed through the tray blocks, and the water-based polyurethane emulsion product is obtained from the kettle of the desolventizing tower.

[0122] Comparative application examples 1-2

[0123] The comparative application example provides a method for removal of solvents from a water-based polyurethane emulsion, which is performed by using the device provided in the comparative examples 1-2, and the temperature of the desolventizing kettle is 40 DEG C and the pressure is 40 kPa.

[0124] The problems and desolventizing efficiency in the desolventizing process of the application examples and the comparison application examples are recorded, the waterborne polyurethane emulsion products obtained in the application examples and the comparison application examples are tested for the residual amount of acetone, the obtained acetone is tested for the water content, and the results are shown in Table 1.

[0125] Table 1

[0126]

[0127]

[0128] As shown in Table 1, the device and method provided by the application adopt the tray with a specific structure, and the heating device is arranged outside the tank of the desolventizing tower, the cooling device and the vacuum device are sequentially connected to the desolventizing tower, the organic solvent is stably and efficiently removed by using the film forming of the emulsion in the desolventizing tower, the emulsion is stable and not easy to foam, and no additional defoaming agent is needed, the residual organic solvent in the emulsion is reduced to less than 10 ppm under the preferred conditions, the product is green and environmentally friendly, and the organic solvent is refined at the same time, the water content in the organic solvent is as low as less than 100 ppm under the preferred conditions, and the organic solvent can be used for subsequent production without further separation and purification by the refining system, which greatly saves the equipment investment cost and the operation cost, and has a wide application prospect.

[0129] The applicant declares that the detailed structural features of the application are illustrated by the above embodiments, but the application is not limited to the above detailed structural features, that is, it does not mean that the application must rely on the above detailed structural features to be implemented. It should be understood by those skilled in the art that any improvement of the application, equivalent replacement of the selected components of the application, addition of auxiliary components, selection of specific modes, etc. fall within the protection scope and disclosure scope of the application.

Claims

1. An apparatus for continuous removal of solvent from an aqueous polyurethane emulsion, characterized by, The device comprises a desolventizing tower, a cooling device and a vacuum device connected in sequence; The desolventizing tower is externally provided with a heating device; The desolventizing tower is internally provided with a plurality of trays, one end of the tray is fixed to the inner wall of the desolventizing tower, and the other end is provided with an overflow weir; The desolventizing tower is internally provided with a distribution device, and the distribution device is arranged at 5%-50% of the liquid holdup height in the tower kettle of the desolventizing tower; The sidewall of the desolventizing tower is provided with a feed inlet; The inner wall of the desolventizing tower is alternately provided with a plurality of trays on the left and right, and the trays are all arranged below the feed inlet; The diameter ratio of the tray to the desolventizing tower is 0.9:1; The spacing between adjacent trays is 200-700mm; A plurality of holes are formed in the tray, and the hole diameter of the hole is 2-20mm; The opening rate of the tray is 3-30%; The tray is vertically arranged with the overflow weir; The height of the overflow weir is 5-50mm.

2. The apparatus of claim 1, wherein, The bottom of the desolventizing tower is provided with a product discharge port.

3. The apparatus of claim 1, wherein, The sidewall of the desolventizing tower is provided with an air inlet.

4. The apparatus of claim 1, wherein, The distribution device is arranged at 10%-20% of the liquid holdup height in the tower kettle of the desolventizing tower.

5. The apparatus of claim 3, wherein, The distribution device is in communication with the pipeline of the air inlet.

6. The apparatus of claim 1, wherein, The spacing between adjacent trays is 400-600mm.

7. The apparatus of claim 1, wherein, The number of trays is 3-15.

8. The apparatus of claim 7, wherein, The number of trays is 6-10.

9. The apparatus of claim 1, wherein, The hole diameter of the hole is 3-10mm.

10. The apparatus of claim 1, wherein, The shape of the hole includes a round hole and / or a square shape.

11. The apparatus of claim 10, wherein, The shape of the hole is a round hole.

12. The apparatus of claim 1, wherein, The opening rate of the tray is 10-20%.

13. The apparatus of claim 1, wherein, The height of the overflow weir is 10-30mm.

14. The apparatus of claim 1, wherein, The heating device comprises a heat preservation jacket.

15. The apparatus of claim 1, wherein, The outlet of the cooling device is connected with an organic solvent storage tank.

16. A method for continuous removal of solvent from an aqueous polyurethane emulsion, characterized in that, The method is carried out by using the device of any one of claims 1-15, comprising the following steps: (1) The aqueous polyurethane emulsion crude product is transported into the desolventizing tower through the feed inlet, the aqueous polyurethane emulsion crude product is distributed on the tray to form a film, and flash separation is carried out at the same time to obtain a flash vapor phase and a flash liquid phase; (2) The flash vapor phase in step (1) is led out to the cooling device through the vacuum device, and the organic solvent is collected after being condensed by the cooling device, and the flash liquid phase in step (1) is sequentially downward through the trays, and the aqueous polyurethane emulsion product is obtained in the tower kettle of the desolventizing tower.

17. The method of claim 16, wherein, The organic solvent in the aqueous polyurethane emulsion crude product in step (1) comprises acetone.

18. The method of claim 16, wherein, Before the transportation in step (1), it further comprises: adjusting the tower kettle temperature of the desolventizing tower by the heating device, and adjusting the tower top pressure of the desolventizing tower by the vacuum device, and then opening the air inlet.

19. The method of claim 16, wherein, The tower kettle temperature of the desolventizing tower is 35-45.

20. The method of claim 16, wherein, The tower top absolute pressure of the desolventizing tower is 30-80kPa.

21. The method of claim 20, wherein, The tower top absolute pressure of the desolventizing tower is 40-55kPa.

22. The method of claim 16, wherein, The temperature of the cooling medium in the cooling device in step (2) is -5~15℃.

23. The method of claim 22, wherein, The temperature of the cooling medium in the cooling device is 0~5℃.

24. The method of claim 16, wherein, The water content in the organic solvent in step (2) is <100ppm.

25. The method of claim 16, wherein, The organic solvent content in the aqueous polyurethane emulsion product in step (2) is <10ppm.

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