A method and device for separating and recycling blended fabrics

Abstract

The invention relates to a blended fabric separation and recovery method and device, and specifically refers to a blended fabric separation and recovery method and device which can save alcoholysis solution. The separation and recovery method comprises the following steps: step one, pretreatment; step two, pre-impregnation: putting the cut cloth ends into a pressure autoclave, adding BHET (ethylene terephthalate), setting the temperature range to 110-120°C, the pressure to 1-2 MPa, and the immersion time to 0.5-1 hour, with slow stirring during the period; step three, alcoholysis; step four, filtering; step five, crystallization; before alcoholysis, using BHET (ethylene terephthalate) solution for pre-impregnation to make cotton fibers fully absorb BHET (ethylene terephthalate), so as to reduce the absorption of alcoholysis solution by cotton fibers during alcoholysis, thereby improving the utilization rate of alcoholysis solution.

Description

Technical Field

[0001] The invention relates to a method and a device for separating and recovering blended fabrics, and in particular to a method and a device for separating and recovering blended fabrics which can save alcoholysis liquid. Background Art

[0002] Blended fabric refers to fabric made by spinning and weaving chemical fibers and natural fibers together. Blended fabric of polyester and cotton has the advantages of high elasticity, light weight and wear resistance, but its recycling is relatively troublesome.

[0003] The prior art (publication number CN105384621A) discloses a method for recycling polyester waste, in which alcoholysis solution and fabric are mixed in a high-pressure reactor. After the reaction is completed, the obtained solution is discharged and the residual solution is collected by vacuum distillation.

[0004] The prior art (publication number CN107308905A) discloses a method for separating the components of waste polyester-cotton blended fabrics, which adopts a horizontal rotary alcoholysis separation device, which has a non-rotating outer cylinder and a rotating inner cylinder, and the alcoholysis liquid can freely pass through the wall of the inner cylinder. The fabric is placed inside the inner cylinder, and the alcoholysis liquid is placed inside the outer cylinder. The inner cylinder rotates continuously instead of stirring.

[0005] Polyester and cotton blended fabric is a mixture of chemical fiber and natural fiber. The microscopic shape of cotton fiber is hollow cylindrical, while polyester fiber is smooth cylindrical. Therefore, cotton fiber has a strong absorption and retention ability for liquids, which is far superior to polyester fiber. When the blended fabric is placed in alcoholysis solution, the cotton fiber will absorb part of the alcoholysis solution. This part of the alcoholysis solution hardly reacts with polyester during the alcoholysis reaction. Although it will be recovered in the final distillation stage, it also causes waste of the alcoholysis solution. Summary of the invention

[0006] One of the purposes of the present invention is to provide a method for separating and recovering blended fabrics which can save alcoholysis liquid, comprising the following steps:

[0007] Step 1, pretreatment: add alkali solution to the recycled polyester fabric, heat it in a water bath at 20-60°C for 1-2 hours, wash and dry it, and cut it into cloth ends.

[0008] Step 2: Pre-preg: Put the cut cloth into a pressure cooker and add BHET (ethylene terephthalate), stirring slowly.

[0009] Step 3, alcoholysis: transfer the cloth after soaking in BHET to an alcoholysis reactor, add an alcoholysis solution formed by mixing ethylene glycol and distilled water, and add a depolymerization catalyst, and react at 170-210°C under normal pressure for 0.4-3 hours, during which time the cloth is continuously stirred and squeezed.

[0010] Step 4, filtration: separate the depolymerized BHET (ethylene terephthalate) from the insoluble matter and collect them for later use.

[0011] Step 5, crystallization: the separated polyester fiber slurry is filtered and cooled again to obtain BHET (ethylene terephthalate) crystals.

[0012] Furthermore, after the cloth is placed in step 2 and before BHET (ethylene terephthalate) is added, the autoclave is evacuated to a vacuum degree of 0 to 100 Pa.

[0013] Furthermore, in step 2, the temperature range is set to 110-120°C, the pressure is 1-2 MPa, and the immersion time is 0.5-1 hour.

[0014] Another object of the present invention is to provide a separation and recovery device which can continuously squeeze the blended fabric during the alcoholysis reaction.

[0015] The technical solution of the present invention is a blended fabric separation and recovery device comprising an alcoholysis reactor, a condenser, a recovery reactor and a transmission device, characterized in that a fixed inner sleeve and a rotating inner cylinder bracket are provided inside the alcoholysis reactor, an inner cylinder is provided on the inner cylinder bracket, ribs are provided on the inner side of the inner sleeve, and the inner cylinder is flexible.

[0016] Furthermore, the inner cylinder is arranged at a position off-center from the inner cylinder support.

[0017] Furthermore, the ribs are spiral.

[0018] Furthermore, the transmission device includes a motor, a belt transmission device and a rotating shaft.

[0019] Furthermore, the inner cylinder support is slidably arranged on the rotating shaft.

[0020] Furthermore, the inner tube is braided.

[0021] Furthermore, the inner cylinder has a plurality of small holes to allow the alcoholysis solution to flow freely.

[0022] The beneficial effects achieved by the present invention using the above structure are as follows:

[0023] (1) Before alcoholysis, the cotton fibers are pre-soaked with BHET (ethylene terephthalate) solution to allow the cotton fibers to fully absorb BHET (ethylene terephthalate), thereby reducing the absorption of alcoholysis solution by the cotton fibers during the alcoholysis process and improving the utilization rate of the alcoholysis solution;

[0024] (2) Ribs are arranged on the inner wall of the reactor. The inner drum is in constant contact with the ribs during rotation, and the ribs continuously squeeze the blended fabric to reduce the alcoholysis liquid remaining in the cotton fiber during the reaction process;

[0025] (3) The flexible inner barrel also has multiple small holes, so the alcoholysis solution and BHET (ethylene terephthalate) solution can flow freely inside and outside the barrel. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the inner wall and inner cylinder structure of the reactor of the present invention;

[0028] Figure 3 It is a schematic diagram of the inner wall structure of the present invention;

[0029] Figure 4 It is a schematic diagram of the content structure of the present invention.

[0030] Among them, 1. alcoholysis reactor; 101. inner sleeve; 102. inner cylinder bracket; 103. inner cylinder; 104. ribs; 2. condenser; 3. recovery kettle; 4. transmission device; 401. motor; 402. belt transmission device; 403. rotating shaft.

[0031] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0032] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0033] This embodiment provides a method and device for separating blended fabrics, which has the characteristics of reducing the absorption of alcoholysis solution by cotton fibers and saving alcoholysis solution.

[0034] Step 1, pretreatment: add alkali solution to the blend of recycled polyester and cotton, heat it in a water bath at 20-60°C for 1-2 hours, wash and dry it, and cut it into cloth ends.

[0035] Step 2, pre-impregnation: put the cut cloth into a pressure autoclave, evacuate the pressure autoclave to a vacuum degree of 0-100 Pa, add BHET (ethylene terephthalate), set the temperature range to 110-120°C, the pressure to 1-2 MPa, and the immersion time to 0.5-1 hour, stirring slowly during the period.

[0036] The air in the cloth can be discharged by evacuating the pressure cooker.

[0037] Using BHET pre-soaking before alcoholysis reaction can effectively reduce the absorption of ethylene glycol by cotton fibers and reduce the amount of solvent required in the alcoholysis process;

[0038] High-pressure pre-impregnation can create a pressure difference between the inside and outside of the cotton fiber, allowing BHET (ethylene terephthalate) to fully penetrate.

[0039] Step 3, alcoholysis: transfer the cloth after soaking in BHET to an alcoholysis reactor, add an alcoholysis solution formed by mixing ethylene glycol and distilled water, and add a depolymerization catalyst, and react at 170-210°C under normal pressure for 0.4-3 hours, during which time the cloth is continuously stirred and squeezed.

[0040] In step 3 of this embodiment, a blended fabric separation and recovery device is also used, such as Figure 1~Figure 4 As shown, it includes an alcoholysis reaction kettle 1, a condenser 2, a recovery kettle 3 and a transmission device 4;

[0041] The inner cylinder support 102 is detachable. Specifically, the inner cylinder support 102 is slidably disposed on the rotating shaft 403 of the transmission device 4;

[0042] Remove the inner cylinder support 102, open the cover plate at the end of the inner cylinder support 102, put the pre-impregnated cloth head in, re-install the inner cylinder support 102, and pass the alcoholysis solution made of ethylene glycol and distilled water;

[0043] The transmission device 4 is connected to the inner cylinder support 102 of the alcoholysis reactor 1, and the motor 401 drives the rotating shaft 403 to rotate through the belt transmission device 402;

[0044] The inner cylinder support 102 on the rotating shaft 403 rotates accordingly, driving the inner cylinder 103 to continuously rotate in the alcoholysis reactor 1, while stirring the alcoholysis liquid;

[0045] The centrifugal force generated by the inner cylinder 103 during the rotation makes the cloth head close to the inner sleeve 101, and the ribs 104 continuously hit the cloth head during the rotation, so that the solution absorbed by the cotton fibers in the cloth head is continuously exchanged with the solution in the reaction kettle;

[0046] After the alcoholysis is completed, the solution in the alcoholysis reactor 1 is released, and the remaining solution in the reactor is evaporated under reduced pressure, and then condensed in the condenser 2 and enters the recovery reactor 3.

[0047] Step 4, filtration: separate the depolymerized BHET (ethylene terephthalate) from the insoluble matter and collect them for later use.

[0048] Step 5, crystallization: the separated polyester fiber slurry is filtered and cooled again to obtain BHET (ethylene terephthalate) crystals.

Claims

1. A blended fabric separation and recovery method, comprising a blended fabric separation and recovery device, the blended fabric separation and recovery device comprising an alcoholysis reactor (1), a condenser (2), a recovery reactor (3) and a transmission device (4), characterized in that: The alcoholysis reaction kettle (1) is further provided with a fixed inner sleeve (101) and a rotating inner cylinder support (102), the inner cylinder support (102) is further provided with an inner cylinder (103), the inner side of the inner sleeve (101) is further provided with ribs (104), and the inner cylinder (103) is flexible; The inner cylinder (103) is arranged at a position off-center of the inner cylinder support (102); The rib (104) is spiral; The transmission device (4) comprises a motor (401), a belt transmission device (402) and a rotating shaft (403); The inner cylinder support (102) is slidably disposed on the rotating shaft (403); The inner cylinder (103) is braided; The inner cylinder (103) has a plurality of small holes to allow the alcoholysis liquid to flow freely; The following steps are also included: Step 1, pretreatment: adding alkali solution to the recycled polyester fabric, heating it in a water bath at 20-60°C for 1-2 hours, washing and drying it, and cutting it into cloth ends; Step 2: Pre-preg: put the cut cloth into a pressure cooker, add BHET (ethylene terephthalate), and stir slowly during the process; Step 3, alcoholysis: transfer the cloth soaked in BHET to an alcoholysis reactor, add an alcoholysis solution prepared by mixing ethylene glycol and distilled water, and add a depolymerization catalyst, and react at 170-210°C under normal pressure for 0.4-3 hours, during which time the cloth is continuously stirred and squeezed; Step 4, filtration: separating the depolymerized BHET (ethylene terephthalate) from the insoluble matter and collecting them for later use; Step 5, crystallization: the separated polyester fiber slurry is filtered and cooled again to obtain BHET (ethylene terephthalate) crystals.

2. The method for separating and recovering blended fabrics according to claim 1, characterized in that: After the cloth is placed in step 2, before adding BHET (ethylene terephthalate), the autoclave is evacuated to a vacuum degree of 0 to 100 Pa.

3. The method for separating and recovering blended fabrics according to claim 1, characterized in that: In step 2, the temperature range is set to 110-120°C, the pressure is 1-2 MPa, and the immersion time is 0.5-1 hour.

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