Preparation method and preparation device of high-efficiency and high-uniformity spandex stock solution

Abstract

The invention relates to a preparation method and a preparation device of a high-efficiency and high-uniformity spandex stock solution, and the preparation method is characterized in that the preparation method comprises the following steps: step 1: a prepolymerization reaction: polyether glycol and DMAC are synchronously metered into a PTG mixing tank to form a PTMEG-DMAC solution, and the mass fraction of the PTMEG-DMAC solution is controlled to be 30-35%; mDI and the PTMEG-DMAC solution are sent into a pipeline reactor through a mass flow meter according to the molar ratio of (1.5-2): 1 to react to prepare an NCO-terminated prepolymer solution, and the mass fraction is controlled to be 35%-40%; 2, filtering and cooling the prepolymer solution, and carrying out an end capping reaction on the prepolymer solution and a DEA-DMAC solution with the mass fraction of 8-15%, wherein the molar ratio of NCO to amino is (10-35): 1; 3, carrying out a chain extension reaction with a chain extender solution with a mass fraction of 5-10% to prepare a high-uniformity spandex stock solution; according to the preparation method and the preparation device of the high-efficiency and high-uniformity spandex stock solution, the homogeneity of a prepolymerization reaction and a chain extension reaction can be remarkably improved, and the quality improvement and consumption reduction effects are remarkable.

Description

Technical Field

[0001] The present invention relates to a method and a device for preparing a spandex stock solution, in particular to a method and a device for preparing a high-efficiency and high-uniform spandex stock solution. Background Art

[0002] The preparation of continuous polymerization spandex stock solution mainly includes prepolymerization and final polymerization. The prepolymerization reaction is usually a bulk polymerization of pure MDI and PTMEG in a specific molar ratio in a pipeline reactor to generate a prepolymer with an NCO group as the terminal group. The prepolymer is then mixed with DMAC in a dissolver to prepare a prepolymer solution and then subjected to final polymerization. The final polymerization reaction is a chain extension reaction of the prepolymer solution and a mixed amine solution, wherein the mixed amine solution is a DMAC solution containing a chain extender and a terminator. The primary stock solution prepared by the chain extension reaction is added with functional additives and then stirred and aged to form a stock solution that can be used for spinning.

[0003] Specifically, existing prepolymerization reactions are bulk polymerizations conducted in pipeline reactors. This poses challenges such as difficulty removing reaction heat, high prepolymer viscosity, and poor fluidity, leading to uneven reactions and numerous side reactions. Furthermore, the pipelines of bulk polymerization reactors are prone to gel blockage over time, resulting in high equipment pressures and requiring regular replacement and cleaning. During chain extension reactions, the simultaneous participation of terminators and chain extenders can affect the participation of the less reactive terminator. Furthermore, existing processes control the viscosity of the polymer solution by adjusting the flow rate of the mixed amine, which simultaneously changes the amounts of both terminator and chain extender. This can alter the ratio of chain-extending amine groups to NCO groups, further affecting the molecular weight and molecular weight distribution uniformity of the polymer.

[0004] Although patent CN101333279A utilizes solution polymerization in the prepolymerization stage, the dilute solution of MDI in DMAC causes the active NCO groups to react with trace amounts of water in the DMAC solvent before reacting with the polyether diol. This in turn leads to an increase in bubbles and impurities in the system, affecting the uniformity of the subsequent prepolymerization reaction and the lifespan of the equipment. Patent CN101096782A also uses solution polymerization to prepare polyurethane elastic fibers, but it is a batch polymerization method, and the prepolymerization temperature is relatively low, resulting in poor reaction results. The chain extension reaction still uses a mixed amine solution containing a terminator and a chain extender, which reduces reaction uniformity and results in poor uniformity of the prepared spinning solution. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method and a device for preparing a high-efficiency and high-uniform spandex stock solution, which can improve the uniformity of the prepolymerization reaction and the chain extension reaction and help reduce production costs.

[0006] The present invention provides a method for preparing a high-efficiency and high-uniform spandex stock solution, which is characterized by: Step 1: Prepolymerization The polyether glycol and DMAC are simultaneously metered into a PTG mixing tank to form a PTMEG-DMAC solution, wherein the mass fraction of the PTMEG-DMAC solution is controlled at 30%-35%, and the water content of the DMAC is controlled below 30 ppm; MDI and the above-mentioned PTMEG-DMAC solution are fed into a pipeline reactor at a molar ratio of (1.5-2):1 through a mass flow meter to react to prepare an NCO-terminated prepolymer solution, with the mass fraction controlled at 35%-40%; The prepolymer solution is filtered through two-stage filters and then sent to the prepolymer storage tank, wherein the filter element specifications are 10μ and 5μ respectively; Step 2: Termination reaction The prepolymer solution cooled by the heat exchanger and the DEA-DMAC solution are simultaneously metered into the dissolver for mixing reaction, wherein the temperature of the prepolymer solution is controlled at 10-20°C, the mass fraction of the DEA-DMAC solution is controlled at 8%-15%, and the temperature of the DEA-DMAC solution is controlled at 2-8°C; Step 3: Chain extension reaction The prepolymer solution subjected to the end-capping reaction is mixed with a mixed amine solution to obtain a polyurethane urea stock solution with a mass concentration of 32%-38%, wherein the molar ratio of the terminal amine in the mixed amine solution to the NCO of the prepolymer solution is (0.98-1.07):1, and the mass fraction of the mixed amine solution is controlled to be 5%-10%; Step 4: Aging and spinning The polyurethane urea stock solution is mixed with the additive solution and then aged to form a highly uniform spandex spinning stock solution for dry spinning to obtain spandex fibers with good heat resistance and resilience.

[0007] Preferably, in the prepolymerization step, the diisocyanate is one or more of 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane dimethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0008] Preferably, the polyether glycol is a mixture of one or more combinations of polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol, and poly-2-methyltetrahydrofuran, and has a molecular weight of 1500-3000.

[0009] Preferably, in the above-mentioned terminator blocking reaction step, the terminator is a mixture of one or more combinations of diethylamine, cyclohexylamine, diisopropylamine, dibutylamine, piperidine, and diethylaminopropylamine; the terminator is diethylamine, and the mass concentration of the terminator solution ranges from 8 to 15%.

[0010] Preferably, in the above-mentioned terminator capping reaction step, the molar ratio of NCO groups to amine groups is (10-35):1.

[0011] Preferably, in the above-mentioned chain extension reaction step, the chain extender is a mixture of one or more combinations of diethylamine, 1,2-propylenediamine, 2-methylpentanediamine, 1,3-propylenediamine, hydrogenated m-phenylenediamine, and isophoronediamine; the chain extender is a mixture of diethylamine and 1,2-propylenediamine, wherein the molar ratio of diethylamine to 1,2-propylenediamine is (60-95): (5-40).

[0012] Preferably, functional additives are selectively added to the above-mentioned polyurethane urea stock solution, and the functional additives include one or more of a matting agent, an antioxidant, an anti-yellowing agent, a lubricant, a dyeing auxiliary, a chlorine-resistant agent, and a cohesive agent; the added amount of the functional additives is calculated based on the mass of the obtained spandex fiber, and the antioxidant is 0.1-1.5%, the matting agent is 0.1-0.5%, the lubricant is 0.1-1.0%, the dyeing auxiliary is 0.1-1.0%, the anti-yellowing agent is 0.1-0.5%, the chlorine-resistant agent is 1-4%, and the cohesive agent is 0.1-1.0%.

[0013] A PTMEG solution was prepared in a PTG mixing tank by mixing polytetramethylene ether glycol with a molecular weight of 1800 at a flow rate of 7108.5 g / min and DMAC at a flow rate of 14005 g / min. The mixing tank jacket was kept warm with 45°C water. 4,4'-diphenylmethane diisocyanate at a flow rate of 1667.4 g / min and PTMEG-DMAC solution at a flow rate of 21113.5 g / min were mixed evenly in a static mixer, heated to 80°C and reacted for 4 hours to obtain a terminal NCO-terminated prepolymer, which was filtered through 10μ and 5μ filters, and then cooled to 15°C with 7°C water in a heat exchanger jacket. It was then mixed with 275.7 g / min of a 10% DEA-DMAC solution in a dissolver to obtain a DEA-terminated prepolymer solution, DEA-DMA Solution C is first cooled to 3° C. by a refrigerant, and the blocked prepolymer solution and a mixed amine solution at a flow rate of 2348 g / min are placed in a second reactor for reaction. The molar ratio of ethylenediamine to 1,2-propylenediamine in the mixed amine solution is 9:1, the amount of diethylenetriamine added is 0.02% by weight of the fiber, and the molar ratio of the chain extender to the terminator diethylamine is 7:1. The additive slurry is added to the stock solution obtained after chain extension in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% of the fiber weight, the titanium dioxide accounts for 0.2% of the fiber weight, the magnesium stearate accounts for 0.3% of the fiber weight, the dyeing auxiliary accounts for 0.3% of the fiber weight, the cohesion agent accounts for 0.3% of the fiber weight, the anti-yellowing agent HN150 accounts for 0.4% of the fiber weight, and the chlorine resistance agent accounts for 2% of the fiber weight. A high-uniform spandex spinning stock solution is prepared and dry spinning is performed.

[0014] A PTMEG solution was prepared in a PTG mixing tank by mixing polytetramethylene ether glycol with a molecular weight of 1800 at a flow rate of 7108.5 g / min and DMAC at a flow rate of 14005 g / min. The mixing tank jacket was kept warm with 45°C water. 4,4'-diphenylmethane diisocyanate at a flow rate of 1667.4 g / min and PTMEG-DMAC solution at a flow rate of 21113.5 g / min were mixed evenly in a static mixer, heated to 80°C and reacted for 4 hours to obtain a terminal NCO-terminated prepolymer, which was filtered through 10μ and 5μ filters, and then cooled to 15°C with water at 7°C in a heat exchanger jacket. The mixture was then mixed with a DEA-DMAC solution with a mass concentration of 10% at a dissolver to obtain a DEA-terminated prepolymer solution. DEA-DMAC The solution is first cooled to 3° C. by a refrigerant, and the above-mentioned blocked prepolymer solution and a mixed amine solution at a flow rate of 2467.2 g / min are placed in a second reactor for reaction, wherein the molar ratio of ethylenediamine and 1,2-propylenediamine in the mixed amine solution is 4:1, the amount of diethylenetriamine added accounts for 0.02% of the fiber mass, the molar ratio of the chain extender and the terminator diethylamine participating in the reaction is 14:1, and the additive slurry is added to the stock solution obtained after chain extension in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% of the fiber mass, the titanium dioxide accounts for 0.2% of the fiber mass, the magnesium stearate accounts for 0.3% of the fiber mass, the dyeing auxiliary accounts for 0.3% of the fiber mass, the bonding agent accounts for 0.3% of the fiber mass, the anti-yellowing agent HN150 accounts for 0.4% of the fiber mass, and the chlorine resistance agent accounts for 2% of the fiber mass, to prepare a high-uniform spandex spinning stock solution and perform dry spinning.

[0015] The spandex stock solution preparation device of the present invention is characterized in that it includes a PTG mixing tank, a pipeline reactor, a prepolymer storage tank, a dissolver, a second reactor and a buffer tank connected in sequence, the inlet end of the pipeline reactor is respectively connected to the PTG mixing tank and the MDI solution tank, a delivery pump is provided between the PTG mixing tank, the MDI solution tank and the inlet end of the pipeline reactor, the outlet end of the pipeline reactor is sequentially connected to the delivery pump, a 10μ filter and a 5μ filter and then connected to the prepolymer storage tank, the inlet end of the dissolver is respectively connected to the prepolymer storage tank and the DEA-DMAC solution tank, the inlet end of the second reactor is respectively connected to the outlet end of the dissolver and the mixed amine solution tank, and the outlet end of the second reactor is connected to the inlet end of the buffer tank.

[0016] Compared with the existing technology, the present invention greatly improves the uniformity of the prepolymerization reaction and the chain extension reaction in the spandex production process by adopting solution polymerization and DEA early end-capping, effectively reduces the generation of system gel, greatly improves the service life of the equipment related to the production process, and has obvious effects of improving quality and reducing consumption. At the same time, due to the improved reaction uniformity, the characteristic viscosity of the spinning solution is improved compared with the existing technology, and the spinning speed can be further increased on the basis of ensuring the stability of fiber performance, which is conducive to reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings; Figure 1 It is a schematic diagram of the working principle of the preparation device of the present invention; Figure 2 、 3 yes Figure 1 A partial view of the . DETAILED DESCRIPTION

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0019] The method for preparing high-efficiency and high-uniform spandex stock solution of the present invention, step 1: prepolymerization reaction The polyether glycol and DMAC are simultaneously metered into the PTG mixing tank to form a PTMEG-DMAC solution. The mass fraction of the PTMEG-DMAC solution is controlled at 30%-35%, and the water content of the DMAC is controlled below 30ppm. Since the introduction of water should be minimized during the prepolymerization stage to avoid excessive NCO groups reacting with water to form small molecules, the water content is adjusted from 60ppm in the conventional process to 30ppm. MDI and the above-mentioned PTMEG-DMAC solution are fed into a pipeline reactor at a molar ratio of (1.5-2):1 through a mass flow meter to react to prepare an NCO-terminated prepolymer solution, with the mass fraction controlled at 35%-40%; The prepolymer solution is filtered through two-stage filters and then sent to the prepolymer storage tank, wherein the filter element specifications are 10μ and 5μ respectively; Step 2: Termination reaction The prepolymer solution cooled by the heat exchanger and the DEA-DMAC solution are simultaneously metered into the dissolver for mixing reaction, wherein the temperature of the prepolymer solution is controlled at 10-20°C, the mass fraction of the DEA-DMAC solution is controlled at 8%-15%, and the temperature of the DEA-DMAC solution is controlled at 2-8°C; Step 3: Chain extension reaction The prepolymer solution subjected to the end-capping reaction is mixed with a mixed amine solution to obtain a polyurethane urea stock solution with a mass concentration of 32%-38%, wherein the molar ratio of the terminal amine in the mixed amine solution to the NCO of the prepolymer solution is (0.98-1.07):1, and the mass fraction of the mixed amine solution is controlled to be 5%-10%; Step 4: Aging and spinning The polyurethane urea stock solution is mixed with the additive solution and then aged to form a highly uniform spandex spinning stock solution for dry spinning to obtain spandex fibers with good heat resistance and resilience.

[0020] In the above-mentioned prepolymerization step, the diisocyanate is one or more of 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane dimethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0021] The polyether glycol is a mixture of one or more combinations of polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol, and poly-2-methyltetrahydrofuran, and has a molecular weight of 1500-3000.

[0022] In the above terminator blocking reaction step, the terminator is a mixture of one or more combinations of diethylamine, cyclohexylamine, diisopropylamine, dibutylamine, piperidine, and diethylaminopropylamine; the terminator is diethylamine, and the mass concentration of the terminator solution ranges from 8 to 15%.

[0023] In the above-mentioned terminator capping reaction step, the molar ratio of NCO groups to amine groups is (10-35):1.

[0024] In the above chain extension reaction step, the chain extender is a mixture of one or more combinations of diethylamine, 1,2-propylenediamine, 2-methylpentanediamine, 1,3-propylenediamine, hydrogenated metaphenylenediamine, and isophoronediamine; the chain extender is a mixture of diethylamine and 1,2-propylenediamine, wherein the molar ratio of diethylamine to 1,2-propylenediamine is (60-95): (5-40).

[0025] Functional additives are selectively added to the above-mentioned polyurethane urea stock solution, and the functional additives include one or more of a matting agent, an antioxidant, an anti-yellowing agent, a lubricant, a dyeing auxiliary, a chlorine-resistant agent, and a cohesive agent; the amount of the functional additives added is calculated based on the mass of the obtained spandex fiber, and the antioxidant is 0.1-1.5%, the matting agent is 0.1-0.5%, the lubricant is 0.1-1.0%, the dyeing auxiliary is 0.1-1.0%, the anti-yellowing agent is 0.1-0.5%, the chlorine-resistant agent is 1-4%, and the cohesive agent is 0.1-1.0%.

[0026] Example 1: A PTMEG solution was prepared in a PTG mixing tank by mixing 7108.5 g / min of polytetramethylene ether glycol with a molecular weight of 1800 and 14005 g / min of DMAC. The mixing tank jacket was insulated with 45°C water. 1667.4 g / min of 4,4'-diphenylmethane diisocyanate and 21113.5 g / min of PTMEG-DMAC solution were mixed uniformly in a static mixer, heated to 80°C and reacted for 4 hours to obtain a terminal NCO-terminated prepolymer, which was filtered through 10μ and 5μ filters, and then cooled to 15°C with 7°C water in a heat exchanger jacket. It was then mixed with 275.7 g / min of a 10% mass concentration of DEA-DMAC solution in a dissolver to obtain a DEA-terminated prepolymer solution. DEA- The DMAC solution is first cooled to 3° C. by a refrigerant, and the blocked prepolymer solution and a mixed amine solution at a flow rate of 2348 g / min are placed in a second reactor for reaction. The molar ratio of ethylenediamine to 1,2-propylenediamine in the mixed amine solution is 9:1, the amount of diethylenetriamine added is 0.02% by weight of the fiber, and the molar ratio of the chain extender to the terminator diethylamine is 7:1. The stock solution obtained after chain extension is added to an additive slurry in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% by weight of the fiber, titanium dioxide accounts for 0.2% by weight of the fiber, magnesium stearate accounts for 0.3% by weight of the fiber, a dyeing auxiliary accounts for 0.3% by weight of the fiber, a cohesive agent accounts for 0.3% by weight of the fiber, an anti-yellowing agent HN150 accounts for 0.4% by weight of the fiber, and a chlorine resistance agent accounts for 2% by weight of the fiber to prepare a high-uniform spandex spinning stock solution and perform dry spinning.

[0027] Example 2: 7108.5 g / min of polytetramethylene ether glycol with a molecular weight of 1800 and 14005 g / min of DMAC were prepared into a PTMEG solution in a PTG mixing tank. The mixing tank jacket was insulated with 45°C water. 1667.4 g / min of 4,4'-diphenylmethane diisocyanate and 21113.5 g / min of PTMEG-DMAC solution were mixed uniformly in a static mixer, heated to 80°C and reacted for 4 hours to obtain a terminal NCO-terminated prepolymer, which was filtered through 10μ and 5μ filters, and then cooled to 15°C with 7°C water in a heat exchanger jacket. It was then mixed with 141.8 g / min of a 10% mass concentration DEA-DMAC solution in a dissolver to obtain a DEA-terminated prepolymer solution. The AC solution is first cooled to 3° C. by a refrigerant, and the above-mentioned blocked prepolymer solution and a mixed amine solution at a rate of 2467.2 g / min are placed in a second reactor for reaction. The molar ratio of ethylenediamine to 1,2-propylenediamine in the mixed amine solution is 4:1, the amount of diethylenetriamine added is 0.02% by weight of the fiber, and the molar ratio of the chain extender to the terminator diethylamine is 14:1. The stock solution obtained after chain extension is added with an additive slurry in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% by weight of the fiber, titanium dioxide accounts for 0.2% by weight of the fiber, magnesium stearate accounts for 0.3% by weight of the fiber, a dyeing auxiliary accounts for 0.3% by weight of the fiber, a cohesive agent accounts for 0.3% by weight of the fiber, an anti-yellowing agent HN150 accounts for 0.4% by weight of the fiber, and a chlorine resistance agent accounts for 2% by weight of the fiber, to prepare a high-uniform spandex spinning stock solution and perform dry spinning.

[0028] The difference between Example 2 and Example 1 is that the molar ratio of ethylenediamine to 1,2-propylenediamine in the mixed amine solution is 4:1, and the molar ratio of the chain extender and terminator diethylamine involved in the reaction is 14:1.

[0029] Comparative Example 1: 1667.4 g / min of 4,4'-diphenylmethane diisocyanate and 7108.5 g / min of polytetramethylene ether glycol (molecular weight: 1800) were mixed uniformly in a static mixer and heated to 90°C for 4 hours to produce an NCO-terminated prepolymer. The prepolymer was then dissolved in a dissolver to form a 38.1% prepolymer solution. The prepolymer solution was reacted with a mixed amine solution in a second reactor. The molar ratio of ethylenediamine to 1,2-propylenediamine in the mixed amine solution was 4:1, the molar ratio of chain extender to terminator diethylamine was 14:1, the amount of diethylenetriamine added was 0.02% by weight of the fiber, and the molar ratio of amine groups in the chain extension reaction to NCO groups was 1.05. The stock solution obtained after chain extension is added with additive slurry in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% of the fiber mass, the titanium dioxide accounts for 0.2% of the fiber mass, the magnesium stearate accounts for 0.3% of the fiber mass, the dyeing auxiliary accounts for 0.3% of the fiber mass, the bonding agent accounts for 0.3% of the fiber mass, the anti-yellowing agent HN150 accounts for 0.4% of the fiber mass, and the chlorine resistance agent accounts for 2% of the fiber mass to prepare a conventional spandex spinning stock solution and perform dry spinning.

[0030] Comparative Example 2: 1667.4 g / min of 4,4'-diphenylmethane diisocyanate and 7108.5 g / min of polytetramethylene ether glycol (molecular weight: 1800) were mixed in a static mixer and heated to 90°C for 4 hours to produce an NCO-terminated prepolymer. The prepolymer was then dissolved in a dissolver to form a 38.1% prepolymer solution. The prepolymer solution was reacted with a mixed amine solution in a second reactor. The molar ratio of ethylenediamine to 1,2-propylenediamine in the mixed amine solution was 9:1, the molar ratio of chain extender to terminator diethylamine was 7:1, the amount of diethylenetriamine added was 0.02% by weight of the fiber, and the molar ratio of amine groups in the chain extension reaction to NCO groups was 1.05. The stock solution obtained after chain extension is added with additive slurry in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% of the fiber mass, the titanium dioxide accounts for 0.2% of the fiber mass, the magnesium stearate accounts for 0.3% of the fiber mass, the dyeing auxiliary accounts for 0.3% of the fiber mass, the bonding agent accounts for 0.3% of the fiber mass, the anti-yellowing agent HN150 accounts for 0.4% of the fiber mass, and the chlorine resistance agent accounts for 2% of the fiber mass to prepare a conventional spandex spinning stock solution and perform dry spinning.

[0031] Performance comparison results of the embodiments of the present invention and the comparative examples:

[0032] From the above comparison results, it can be seen that the service life of the 10μ filter, prepolymerization reactor, stock solution filter and spinning assembly in the embodiment is significantly increased compared with the comparative example, which indicates that the amount of gel in both the prepolymerization reaction and the chain extension reaction has decreased, and the reaction uniformity has been significantly improved. The embodiment has higher dynamic viscosity and characteristic viscosity than the comparative example, which can support the increase in spinning speed. It can be seen that the stress CV value of the embodiment at a spinning speed of 900 m / min is better than the CV value of 800 m / min of the comparative example.

[0033] The invention discloses a device for preparing a high-efficiency and high-uniform spandex stock solution, comprising a PTG mixing tank 1, a pipeline reactor 2, a prepolymer storage tank 3, a dissolver 4, a second reactor 5 and a buffer tank 6, which are connected in sequence. The inlet of the pipeline reactor 2 is respectively connected to the PTG mixing tank 1 and the MDI solution tank 7. A delivery pump is provided between the PTG mixing tank 1, the MDI solution tank 7 and the inlet of the pipeline reactor. The outlet of the pipeline reactor 2 is sequentially connected to the delivery pump, a 10μ filter and a 5μ filter, and then to the prepolymer storage tank 3. The inlet of the dissolver 4 is respectively connected to the prepolymer storage tank 3 and the DEA-DMAC solution tank 8. The inlet of the second reactor 5 is respectively connected to the outlet of the dissolver 4 and the mixed amine solution tank 9. The outlet of the second reactor 5 is connected to the inlet of the buffer tank 6.

[0034] A PTG solution tank 11 is provided between the PTG mixing tank 1 and the pipeline reactor 2, and a prepolymer storage tank is also provided between the pipeline reactor 2 and the filter; a heat exchanger 12 is provided between the prepolymer storage tank 3 and the dissolver 4, and the PTG mixing tank 1 and the buffer tank 6 are provided with a stirring shaft extending into the tank body and driven by a motor.

[0035] The present invention has the following significant differences and advantages over the prior art: 1. Solution polymerization is adopted in the prepolymerization stage. First, a mixed solution of PTMEG and DMAC is prepared with a concentration of about 33.5%. The solution is then fed into a pipeline reactor simultaneously with pure MDI for prepolymerization. The reaction temperature is controlled at about 80°C during this process. 2. The prepolymer solution is fed into a prepolymer storage tank after two filtration steps. A two-stage filtration device is used to reduce the gel of the prepolymer reaction from entering the chain extension reaction. The prepolymer solution is cooled to 15°C with 7°C water before entering the dissolving machine, and then preliminarily reacted with a DMAC solution containing a terminator. The process comprises the following steps: 1. a first step reaction, wherein the terminator is diethylamine with a mass fraction of 8-15%; 2. the prepolymer solution containing monoamine end-capping after the initial reaction enters the second reactor for chain extension reaction, and the chain extender solution is a DMAC solution of ethylenediamine, propylenediamine and diethylenetriamine with a mass fraction of 5-10%; 3. the DEA solution is initially reacted with the prepolymer solution in the dissolver to improve the end-capping effect of DEA, while controlling the mass fraction of the DEA solution at 8-15%, which allows the viscosity of each gram of DEA solution to be adjusted to about 100 poises; the viscosity is controlled by adjusting the flow rate of the terminator solution during the production process.

[0036] Compared with the existing technology, the present invention greatly improves the uniformity of the prepolymerization reaction and the chain extension reaction in the spandex production process by adopting solution polymerization and DEA early end-capping, effectively reduces the generation of system gel, greatly improves the service life of the equipment related to the production process, and has obvious effects of improving quality and reducing consumption. At the same time, due to the improved reaction uniformity, the characteristic viscosity of the spinning solution is improved compared with the existing technology, and the spinning speed can be further increased on the basis of ensuring the stability of fiber performance, which is conducive to reducing production costs.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A method for preparing a high-efficiency and high-uniform spandex stock solution, characterized in that: Step 1: Prepolymerization The polyether glycol and DMAC are simultaneously metered into a PTG mixing tank to form a PTMEG-DMAC solution, wherein the mass fraction of the PTMEG-DMAC solution is controlled at 30%-35%, and the moisture content of the DMAC is controlled below 30 ppm; MDI and the above-mentioned PTMEG-DMAC solution are fed into a pipeline reactor at a molar ratio of (1.5-2):1 through a mass flow meter to react to prepare an NCO-terminated prepolymer solution, with the mass fraction controlled at 35%-40%; The prepolymer solution is filtered through two-stage filters and then sent to the prepolymer storage tank, wherein the filter element specifications are 10μ and 5μ respectively; Step 2: Termination reaction The prepolymer solution cooled by the heat exchanger and the DEA-DMAC solution are simultaneously metered into the dissolver for mixing reaction, wherein the temperature of the prepolymer solution is controlled at 10-20°C, the mass fraction of the DEA-DMAC solution is controlled at 8%-15%, and the temperature of the DEA-DMAC solution is controlled at 2-8°C; Step 3: Chain extension reaction The prepolymer solution subjected to the end-capping reaction is mixed with a mixed amine solution to obtain a polyurethane urea stock solution with a mass concentration of 32%-38%, wherein the molar ratio of the terminal amine in the mixed amine solution to the NCO of the prepolymer solution is (0.98-1.07):1, and the mass fraction of the mixed amine solution is controlled to be 5%-10%; Step 4: Aging and spinning The polyurethane urea stock solution is mixed with the additive solution and then aged to form a highly uniform spandex spinning stock solution for dry spinning to obtain spandex fibers with good heat resistance and resilience.

2. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, wherein: In the prepolymerization step, the diisocyanate is one or more of 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane dimethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

3. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, wherein: The polyether glycol is a mixture of one or more combinations of polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol, and poly-2-methyltetrahydrofuran, and has a molecular weight of 1500-3000.

4. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, wherein: In the terminator blocking reaction step, the terminator is a mixture of one or more combinations of diethylamine, cyclohexylamine, diisopropylamine, dibutylamine, piperidine, and diethylaminopropylamine; the terminator is diethylamine, and the mass concentration of the terminator solution ranges from 8 to 15%.

5. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, wherein: In the terminator blocking reaction step, the molar ratio of NCO groups to amine groups is (10-35):

1.

6. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, characterized in that: In the chain extension reaction step, the chain extender is a mixture of one or more of diethylamine, 1,2-propylenediamine, 2-methylpentanediamine, 1,3-propylenediamine, hydrogenated metaphenylenediamine, and isophoronediamine; the chain extender is a mixture of diethylamine and 1,2-propylenediamine, wherein the molar ratio of diethylamine to 1,2-propylenediamine is (60-95): (5-40).

7. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, characterized in that: Functional additives are selectively added to the polyurethane urea stock solution, and the functional additives include one or more of a matting agent, an antioxidant, an anti-yellowing agent, a lubricant, a dyeing auxiliary, a chlorine-resistant agent, and a bonding agent; the amount of the functional additives added is calculated based on the mass of the obtained spandex fiber, and the antioxidant: 0.1-1.5%, matting agent: 0.1-0.5%, lubricant: 0.1-1.0%, dyeing auxiliary: 0.1-1.0%, anti-yellowing agent: 0.1-0.5%, chlorine resistance agent: 1-4%, bonding agent: 0.1-1.0%.

8. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, characterized in that: A PTMEG solution was prepared in a PTG mixing tank by mixing polytetramethylene ether glycol with a molecular weight of 1800 at a flow rate of 7108.5 g / min and DMAC at a flow rate of 14005 g / min. The mixing tank jacket was kept warm with 45°C water. 4,4'-diphenylmethane diisocyanate at a flow rate of 1667.4 g / min and PTMEG-DMAC solution at a flow rate of 21113.5 g / min were mixed evenly in a static mixer, heated to 80°C and reacted for 4 hours to obtain a terminal NCO-terminated prepolymer, which was filtered through 10μ and 5μ filters, and then cooled to 15°C with 7°C water in a heat exchanger jacket. It was then mixed with 275.7 g / min of a 10% DEA-DMAC solution in a dissolver to obtain a DEA-terminated prepolymer solution, DEA-DMA Solution C is first cooled to 3° C. by a refrigerant, and the blocked prepolymer solution and a mixed amine solution at a flow rate of 2348 g / min are placed in a second reactor for reaction. The molar ratio of ethylenediamine to 1,2-propylenediamine in the mixed amine solution is 9:1, the amount of diethylenetriamine added is 0.02% by weight of the fiber, and the molar ratio of the chain extender to the terminator diethylamine is 7:

1. The additive slurry is added to the stock solution obtained after chain extension in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% of the fiber weight, the titanium dioxide accounts for 0.2% of the fiber weight, the magnesium stearate accounts for 0.3% of the fiber weight, the dyeing auxiliary accounts for 0.3% of the fiber weight, the cohesion agent accounts for 0.3% of the fiber weight, the anti-yellowing agent HN150 accounts for 0.4% of the fiber weight, and the chlorine resistance agent accounts for 2% of the fiber weight. A high-uniform spandex spinning stock solution is prepared and dry spinning is performed.

9. The method for preparing a high-efficiency and high-uniform spandex stock solution according to claim 1, wherein: A PTMEG solution was prepared in a PTG mixing tank by mixing polytetramethylene ether glycol with a molecular weight of 1800 at a flow rate of 7108.5 g / min and DMAC at a flow rate of 14005 g / min. The mixing tank jacket was kept warm with 45°C water. 4,4'-diphenylmethane diisocyanate at a flow rate of 1667.4 g / min and PTMEG-DMAC solution at a flow rate of 21113.5 g / min were mixed evenly in a static mixer, heated to 80°C and reacted for 4 hours to obtain a terminal NCO-terminated prepolymer, which was filtered through 10μ and 5μ filters, and then cooled to 15°C with water at 7°C in a heat exchanger jacket. The mixture was then mixed with a DEA-DMAC solution with a mass concentration of 10% at a dissolver to obtain a DEA-terminated prepolymer solution. DEA-DMAC The solution is first cooled to 3° C. by a refrigerant, and the above-mentioned blocked prepolymer solution and a mixed amine solution at a flow rate of 2467.2 g / min are placed in a second reactor for reaction, wherein the molar ratio of ethylenediamine and 1,2-propylenediamine in the mixed amine solution is 4:1, the amount of diethylenetriamine added accounts for 0.02% of the fiber mass, the molar ratio of the chain extender and the terminator diethylamine participating in the reaction is 14:1, and the additive slurry is added to the stock solution obtained after chain extension in a buffer tank, wherein the antioxidant 1790 accounts for 0.3% of the fiber mass, the titanium dioxide accounts for 0.2% of the fiber mass, the magnesium stearate accounts for 0.3% of the fiber mass, the dyeing auxiliary accounts for 0.3% of the fiber mass, the bonding agent accounts for 0.3% of the fiber mass, the anti-yellowing agent HN150 accounts for 0.4% of the fiber mass, and the chlorine resistance agent accounts for 2% of the fiber mass, to prepare a high-uniform spandex spinning stock solution and perform dry spinning.

10. A preparation device for realizing the method for preparing spandex stock solution according to any one of claims 1 to 9, characterized in that: The invention comprises a PTG mixing tank, a pipeline reactor, a prepolymer storage tank, a dissolver, a second reactor and a buffer tank which are connected in sequence. The inlet of the pipeline reactor is respectively connected to the PTG mixing tank and the MDI solution tank. A delivery pump is provided between the PTG mixing tank, the MDI solution tank and the inlet of the pipeline reactor. The outlet of the pipeline reactor is sequentially connected to the delivery pump, a 10μ filter and a 5μ filter and then to the prepolymer storage tank. The inlet of the dissolver is respectively connected to the prepolymer storage tank and the DEA-DMAC solution tank. The inlet of the second reactor is respectively connected to the outlet of the dissolver and the mixed amine solution tank. The outlet of the second reactor is connected to the inlet of the buffer tank.

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