CN116082614A - Preparation method of circularly regenerated anti-pilling cationic dyeable polyester chip - Google Patents

Abstract

The invention provides a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip, which comprises the steps of raw material cleaning, alcoholysis, transesterification, modification, polycondensation and the like; according to the invention, the three-step alcoholysis method is used for carrying out the alcoholysis reaction of the PET polyester raw material, so that the time of the ethylene glycol in a high-temperature and high-pressure state is reduced, the occurrence of side reaction is reduced, and the purity of the product is improved; the extrusion force and the shearing force generated during the operation of the screw extruder are utilized to locally pressurize the internal polyester and glycol vapor, so that the reaction degree in the first-step depolymerization process is improved; the alcoholysis mother liquor is used as a solvent for the second alcoholysis, so that the generation of glycol steam and polyether is avoided. The invention adopts DMT method to prepare pre-polymer powder of anti-pilling agent in advance, avoids the contact of the anti-pilling agent with water produced by the system, and well solves the problem of hydrolysis of the anti-pilling agent. The invention can adopt automatic control continuous production, has wide application range and is beneficial to industrialized mass production.

Description

Preparation method of circularly regenerated anti-pilling cationic dyeable polyester chip

Technical Field

The invention relates to the technical field of polyester synthesis, in particular to a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip.

Background

PET (polyethylene terephthalate) has found wide application in apparel textiles, industrial films, food and beverage packaging with its excellent properties. With the expansion of polyester productivity and application range, the treatment of waste polyester articles becomes an important problem. Textiles and packages produced from polyester as raw materials are used and discarded in large quantities each year to become garbage, and a large amount of energy is consumed and carbon emission is generated for treatment.

PET recycling includes physical and chemical methods. The physical method is to grind and clean the recycled raw materials, melt filter and granulate for regeneration. The method has the advantages of simple equipment and process, high impurity content, single variety and incapability of carrying out differential modification.

The chemical method comprises the whole process of cleaning and crushing, depolymerizing, modifying and repolymerizing and granulating the recycled raw materials, wherein the depolymerizing step is a core part, and the adopted methods include alcoholysis, acidolysis, hydrolysis, alkaline hydrolysis, composite depolymerization and the like. Among them, alcoholysis is the most dominant method of use: namely, the polyester molecules are subjected to ester group cleavage at high temperature by using a mono-alcohol or a polyol to finally form small molecular oligomers or monomers for further polycondensation to obtain new polyester products. The existing alcoholysis methods mainly comprise methanolysis, glycolysis and mixed alcohol (methanol and glycol) alcoholysis, and each of the three methods has certain defects. Methanol has small molecular weight and low boiling point, needs to keep higher pressure of a system to reach the temperature required by alcoholysis, and has higher volatility than ethylene glycol, so that the alcoholysis is difficult to thoroughly carry out; in the mode of glycol alcoholysis, because glycol itself is easy to generate various side reactions at high temperature, and because the system polycondensation and alcoholysis are reciprocal reactions, the alcoholysis is difficult to complete without large molar ratio; the mode of the co-alcoholysis of the methanol and the glycol is that the alcoholysis of the glycol is followed by the transesterification of the methanol, which solves the defect of the alcoholysis of the mono-alcohol, but the process is complex, the energy consumption and the consumption are high, and the yield is relatively low. In all three methods, a large amount of auxiliary materials are required to be added, and finally, the auxiliary materials are left in the product completely, so that the quality of the final product is seriously reduced.

In addition, one of the production difficulties of anti-pilling chips is the problem of hydrolysis of the silicon-containing additives as anti-pilling agents. Therefore, the true anti-pilling slice requires DMT (dimethyl terephthalate) method, and in theory, the conventional anti-pilling method can also be directly hydrolyzed by PET. However, the introduction of trismonomer SIPA (sodium isophthalic acid-5-sulfonate) in the production of cationically dyeable polyesters, the system will have water generation, thereby promoting hydrolysis of the anti-pilling agent, and therefore, the cationic dyeability of the polyester material is difficult to be effectively combined with the anti-pilling function.

Disclosure of Invention

Aiming at the defects existing in the prior art, the invention provides a preparation method for producing cyclic regenerated anti-pilling cationic dyeable polyester chips by using a recycling raw material through a chemical method. The invention adopts a three-stage alcoholysis method to solve the problems of more auxiliary materials, serious side reaction, low slicing quality and high energy consumption in the traditional method and also solves the problem of hydrolysis of the anti-pilling additive.

According to an embodiment of the invention, a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip comprises the following steps:

s1, performing label removal on a recovered PET polyester material, crushing the recovered PET polyester material into square small pieces with the size of 0.5-2.0cm by using a crusher, immersing the square small pieces in hot water, adding a stripping agent and a PET cleaning agent for stirring and cleaning, and repeatedly cleaning the square small pieces with clear water until no PET recovered raw material exists;

s2, preparing alcoholysis mother liquor: putting the treated PET recovered raw material, glycol and catalyst into an alcoholysis reaction kettle, heating to 220 ℃ under the coverage of nitrogen, starting a stirrer, quickly heating to 255 ℃, keeping the temperature for 5-6 hours, heating to 260 ℃ and continuously stirring for 30-60 minutes, and then cooling to 220 ℃;

s3, putting the PET recovery raw material into a high-speed mixer, adding ethylene glycol accounting for 5-10% of the PET recovery raw material, a stabilizer and an antioxidant, uniformly stirring, then feeding into a screw extruder, enabling the material to be melt extruded through the screw extruder at 270-290 ℃ and in a high-pressure environment, enabling the tail end of the screw extruder to be provided with a filter screen F0, enabling the extruded melt to enter an alcoholysis reaction kettle through a melt pipe to react with alcoholysis mother liquor for 30-60 minutes, then pumping MEG accounting for 15-35% of the PET recovery raw material from the bottom of the alcoholysis reaction kettle, and keeping the temperature of 180-220 ℃ for further alcoholysis for 2-4 hours to reach the required alcoholysis degree;

s4, pressing an alcoholysis product of the S3 into a filter F1 through high-pressure nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis liquid diversion kettle, uniformly dividing alcoholysis liquid into two parts, returning one part of alcoholysis liquid as alcoholysis mother liquid into the alcoholysis reaction kettle, and enabling the other part of alcoholysis liquid to enter a modification reaction kettle for modification: adding normal-temperature MEG with the mass of 0-10% of the PET recovery raw material, conducting further alcoholysis for 30-60 minutes, then respectively adding a tri-monomer with the weight of 2.4-3.3% of the PET recovery raw material and a tetra-monomer with the weight of 0.5-1.5% of the PET recovery raw material and a slip agent through a multi-way feeding pipe under the protection of nitrogen, and stirring for 30 minutes at the temperature of 230-240 ℃ to obtain a modified esterified substance;

s5, pressing the modified esterified substance into a polycondensation kettle through a filter F2 by high-pressure nitrogen, vacuumizing by a vacuum system to perform a prepolymerization reaction, wherein the reaction set temperature is 260-275 ℃, and the vacuum degree is 0.6-2.0KPa; starting a vacuum system, gradually establishing vacuum, maintaining for 20-40 minutes after reaching the target vacuum degree, and closing the vacuum system after the prepolymerization reaction is finished; under the protection of nitrogen and negative pressure, adding the prepared anti-pilling agent powder into a polycondensation kettle through a feeder, and stirring and mixing for 5-10 minutes, wherein the adding amount of the anti-pilling agent is 0.15-0.25% of the weight of the PET recovered raw material; finally, carrying out final polycondensation reaction at 270-285 ℃ and under 40-100Pa, discharging and granulating after the final polycondensation reaction is finished, and obtaining the cyclic regenerated anti-pilling cationic dyeable polyester chip product.

Furthermore, stabilizing agents, antioxidants and slip agents are added in the steps S2, S3 and S4, and the addition amounts of the stabilizing agents and the antioxidants are 0.2-0.8 per mill of the weight of the regenerated recycled material.

Further, in the steps S2, S3 and S4, the antioxidants are hindered phenol antioxidants, the stabilizer is hindered amine light stabilizer, and the slip agent is silica, preferably membrane opening agent silica with particle size smaller than 5 mu.

Further, the preparation method of the anti-pilling agent powder in the step S5 comprises the following steps: adding the components according to the following formula 3:1:4, adding MEG, diphenyl dihydroxysilane (DHDPS) and dimethyl terephthalate (DMT) according to the proportion, heating to 140 ℃, then heating, starting stirring, gradually heating to 220 ℃ within 3 hours, heating to 280 ℃ after methanol is not distilled, vacuumizing until the pressure is lower than 100Pa, reacting for 60-90 minutes, discharging, cooling, and crushing to obtain the anti-pilling agent.

Further, in the step S4, the trisonomer is dimethyl isophthalate-5-sodium Sulfonate (SIPM) or isophthalic acid-5-sodium Sulfonate (SIPA), or diethylene glycol isophthalate-5-sodium sulfonate (ssppa), and the added weights are converted by SIPA.

Further, the tetra-monomer in the step S4 is polyethylene glycol (PEG) with a molecular weight between 600 and 4000.

Further, the tetra-monomer in the step S4 can also be an ethylene glycol adipate oligomer with a hydroxyl value of 50-110 mgKOH/g.

Further, the hot water temperature during the washing in the step S1 is more than 90 ℃, preferably more than 95 ℃, and the water content of the dehydrated PET recycled raw material is not more than 4%o.

Further, in the step S2, part of MEG may be injected at a high pressure from the middle of the extruder during the extrusion and melting process of the material through the screw extruder.

Further, the filtering precision of the filters F0, F1 and F2 in the steps S3, S4 and S5 is 48-150 μm, 5-25 μm and 15-30 μm respectively.

Further, when the polyester chip product is used for spinning long fibers, the addition amount of the anti-pilling agent is 0.1 to 0.25 percent of the weight of the PET recovery raw material; when the anti-pilling agent is used for spinning short fibers, the addition amount of the anti-pilling agent is 0.2-0.5% of the weight of the PET recovery raw material, and the anti-pilling agent is diphenyl dihydroxy silane.

Further, the catalyst in the step S2 refers to zinc acetate or manganese acetate or a mixture of zinc acetate and manganese acetate, and the concentration of the catalyst is not more than 200ppm.

Further, the stripping agent in the step S1 adopts long-chain alkyl quaternary ammonium salt, and the adding amount is 30-100ppm.

The technical principle of the invention is as follows:

the invention uses three-step alcoholysis method, uses high-temperature glycol steam, alcoholysis mother liquor containing BHET and glycol liquid to carry out alcoholysis reaction, gradually reduces reaction conditions, and thus completes alcoholysis process rapidly with low consumption and low reaction.

The first step of alcoholysis is carried out in a screw extruder, the PET recovered raw material in a molten state is contacted with ethylene glycol vapor in a short time under the conditions of high temperature, high pressure and high shear, and preliminary depolymerization reaction is rapidly carried out, wherein the reaction process only occurs in the process that the PET recovered raw material passes through the screw extruder, so that degradation and less oxidation side reaction possibly occur are avoided due to short high-temperature time, and meanwhile, the overall concentration is low due to less ethylene glycol addition, so that the side reaction is less. In addition, the boiling point of the glycol is 197 ℃, and the system temperature is above 270 ℃, and the glycol is in a high-activity state at the temperature, so that the alcoholysis reaction can occur more rapidly, and the improvement of the reaction efficiency is facilitated. In addition, in the feeding process of the screw, the screw can simultaneously generate axial conveying pressure and tangential shearing force on the raw materials, so that the mixing pressure between the raw material melt and the ethylene glycol is locally increased, and the alcoholysis speed is further improved.

The second step of alcoholysis is carried out in an alcoholysis reaction kettle, and the alcoholysis mother liquor returned from the previous batch (or prepared for the first time) is prepared in the reaction kettle, and the main component of the alcoholysis mother liquor is BHET (dihydroxyethyl terephthalate), and the oligomer after preliminary alcoholysis and the BHET undergo transesterification reaction, so that the polymerization degree is further reduced. In this stage, the melt melting point of the screw extrusion addition is also relatively high, and if the alcoholysis is carried out by directly adding liquid ethylene glycol, it is necessary to maintain the high temperature, high pressure and high concentration state, in which case the ethylene glycol is extremely etherified (DEG, TEG is produced) or cyclized (dioxane is formed). The raw materials in the invention react with BHET in advance more gently, so that the polymerization degree of the raw materials is further reduced, and the overall temperature is also reduced.

The third step of alcoholysis is still carried out in an alcoholysis reaction kettle, after the reaction with BHET, the polymerization degree of the system is very low, the melting point of the oligomer is reduced to be lower than 150 ℃, the melting point of the oligomer is far lower than the boiling point of ethylene glycol to 197 ℃, the ethylene glycol at normal temperature can be directly introduced without additionally maintaining higher temperature, and the mixture is mixed and dissolved at lower temperature and undergoes the final depolymerization reaction. According to the invention, ethylene glycol is introduced from the bottom of the alcoholysis reaction kettle, is contacted with the system materials first, and is reacted with the materials first before being evaporated at high temperature in the reaction kettle, so that evaporation when introduced from the top is avoided, the reaction efficiency of ethylene glycol is improved, and the use amount of ethylene glycol is reduced.

Meanwhile, the invention adopts DMT method to prepare pre-polymer powder of anti-pilling agent in advance, and then adds the pre-polymer powder into the system in the later stage of polycondensation, thereby avoiding the contact between the anti-pilling agent and the water produced by the system and well solving the problem of hydrolysis of the anti-pilling agent.

Compared with the prior art, the invention has the following beneficial effects:

1. the three-step alcoholysis method is used for carrying out the alcoholysis reaction of the PET polyester raw material, wherein the reaction conditions of each step are gradually gentle, so that the time of the ethylene glycol in a high-temperature and high-pressure state is reduced, the occurrence of side reaction is greatly reduced, and the purity of the product is improved;

2. compared with the mode of directly introducing ethylene glycol into the alcoholysis reaction kettle in the traditional method, the method has the advantages that the ethylene glycol is respectively added into the screw extruder in the form of high-temperature steam and introduced from the bottom of the alcoholysis reaction kettle, so that the use amount of the ethylene glycol can be reduced, the extraction amount of the ethylene glycol in the later polymerization is reduced, and the consumption and recovery cost are reduced;

3. according to the invention, the screw extruder is used as a reaction vessel of the first step in the alcoholysis reaction, and the extrusion force and the shearing force generated during the operation of the screw extruder are utilized to locally pressurize the melt and the ethylene glycol vapor, so that the depolymerization reaction can be more fully carried out, and the reaction degree in the first step depolymerization process is improved;

4. the anti-pilling agent is prepared with DMT in advance, transesterification and polycondensation reactions occur in the preparation process, so that the polyester silane copolymer with low polymerization degree is obtained, and the polyester silane copolymer is added after the pre-polymerization, so that the anti-pilling agent is prevented from being contacted with water of a reaction system to generate hydrolysis reaction, and the anti-pilling agent can be better reacted with an active end group to enter a link better;

5. in the invention, besides the catalyst used for preparing the mother solution, the catalyst is avoided in the whole reaction process, so that the introduction of foreign matters is reduced, and the quality of the product is improved.

6. The invention adopts a method of pre-synthesizing the anti-pilling agent prepolymer, avoids the contact of the anti-pilling agent with water produced by a system, well solves the problem of hydrolysis of the silicon-containing anti-pilling agent, and can produce anti-pilling slices with higher viscosity.

7. The invention can be implemented by adopting automatic industrial equipment, has wide application range and is beneficial to industrialized mass production.

Drawings

Fig. 1 is a device connection flow chart of the present invention.

In the figure: 1. a screw extruder; 2. an alcoholysis reaction kettle; 3. a sieve (F0); 4. a filter (F1); 5. an alcoholysis liquid split-flow kettle; 6. a modification reaction kettle; 7. a multi-path feeding pipe; 8. a filter (F2); 9. a polycondensation kettle; 10. and a feeder.

Screw extruder 1, alcoholysis reaction kettle 2, filter screen (F0) 3, filter (F1) 4, alcoholysis liquid reposition of redundant personnel cauldron 5, modification reaction kettle 6, multichannel filling tube 7, filter (F2) 8, polycondensation cauldron 9, feeder 10.

Detailed Description

The technical scheme of the invention is further described below with reference to the accompanying drawings and examples.

In all examples of the present invention, the pretreatment and preparation of the raw materials were consistent:

1. treatment and preparation of regenerated and recycled raw materials: removing labels from the recovered polyester beverage bottles, crushing the plastic bottles by using a crusher, putting the crushed plastic bottles into hot water with the temperature of more than 90 ℃, adding a stripping agent and a surfactant, stirring and cleaning, repeatedly cleaning with clear water until no other washing components remain, and finally dehydrating to obtain PET recovered raw materials, wherein the water content of the dehydrated PET recovered raw materials is not more than 4 per mill;

2. establishing alcoholysis mother liquor: adding 100kg of treated PET recovered raw materials, 25kg of ethylene glycol and 100g of catalyst into an alcoholysis reaction kettle, adding an antioxidant and a stabilizer, heating to 220-250 ℃ under nitrogen coverage, starting an alcoholysis stirrer, keeping the temperature for 5-6 hours, heating to 260 ℃ and continuously stirring for 30-60 minutes, and then cooling to 220 ℃;

3. preparing antioxidant and stabilizer solution: 200g of antioxidant is dissolved in 5000g of glycol, heated to 120 ℃, stirred until the antioxidant is in a homogeneous state, and then acetic acid is added until the pH value is 4-5, so as to obtain an antioxidant solution; 200g of stabilizer is dissolved in 5000g of glycol, heated to 120 ℃, stirred until the mixture is in a homogeneous state, and then acetic acid is added until the pH value is 4-5 to obtain a stabilizer solution;

4. the preparation method of the anti-pilling agent comprises the following steps: adding the materials according to the following formula 4:3: 1, adding DMT, MEG and DHDPS according to the weight ratio, heating to 140 ℃, then heating, starting stirring, gradually heating to 220 ℃ within 3 hours, vacuumizing until the methanol is not distilled off until the pressure is lower than 100Pa, maintaining for 60 minutes, discharging, cooling and crushing to obtain the anti-pilling agent;

5. the preparation of the three-monomer esterified liquid accords with the general method for preparing the conventional cationic dyeable polyester chip three-monomer, and the SSIPA (dihydroxyethyl isophthalate-5-sodium sulfonate) content in the prepared three-monomer is 40%; the amount of the added tri-monomer described below is the amount of the tri-monomer active ingredient, i.e., sodium isophthalic acid-5-sulfonate (or, the amount is not the amount of the tri-monomer esterified liquid).

6. Preparing PEG, stirring and melting at 80-100deg.C;

7. preparation of polyethylene glycol adipate: in the reactor with distillation column, the reaction ratio was 1: adding adipic acid, glycol and a small amount of p-toluenesulfonic acid according to the molar ratio of 4, heating and stirring to 170 ℃ for 120 minutes, heating the system to 200 ℃ and then maintaining for 120 minutes, sampling and calculating the hydroxyl value until the proper water yield is reached, and adding glycol with the molar number of 2 times of adipic acid for cooling. Stirring was maintained.

Specific examples are as follows:

example 1:

the embodiment provides a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip, which comprises the following steps:

s1, recycling 100kg of PET (polyethylene terephthalate) raw materials, putting the PET raw materials into a mixer, adding 5kg of MEG, uniformly stirring, and then putting the mixture into a screw extruder 1, so that the materials pass through the screw extruder 1 provided with a filter screen (F0) 3 at 275 ℃ under high-pressure environment; then all materials enter an alcoholysis reaction kettle 2 to react with alcoholysis mother liquor, 15kg of MEG is pumped from the bottom of the alcoholysis reaction kettle 2 after 30 minutes, and the mixture is stirred for 90 minutes at 220 ℃ to perform further alcoholysis reaction until the required alcoholysis degree is reached;

s2, pressing an alcoholysis product of the S1 into a filter (F1) 4 through nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis liquid diversion kettle 5, adding an antioxidant and a stabilizer, uniformly dividing the alcoholysis liquid into two parts, returning one part to the alcoholysis reaction kettle 2 to serve as alcoholysis mother liquid for the next reaction, and enabling the other part to enter a modification reaction kettle 6 to be modified: adding 10kg of MEG and 30g of silicon dioxide at normal temperature, cooling the mixture to 200 ℃ and keeping the temperature, and then respectively adding 2.4kg of tri-monomer and 0.5kg of tetra-monomer under the protection of nitrogen through a multi-way feeding pipe 7, wherein the tri-monomer is isophthalic acid-5-sulfonic acid, the tetra-monomer is PEG with the molecular weight of 1000, stirring and keeping the temperature for 30 minutes to obtain a modified esterified product;

s3, enabling the modified esterified substance to enter a polycondensation kettle 9 after passing through a filter (F2) 8, and vacuumizing to perform a prepolymerization reaction, wherein the prepolymerization reaction temperature is 260 ℃, and the vacuum degree is 0.6KPa; after the prepolymerization reaction is finished, closing a vacuum system, adding 0.1kg of prepared anti-pilling agent powder into a polycondensation kettle 9 through a feeder 10 under the protection of nitrogen and negative pressure, and stirring and mixing; finally, carrying out final polymerization at the temperature of 275 ℃ and the pressure of 100Pa, discharging and granulating after the final polymerization is finished, and obtaining 101.6kg of the circularly regenerated anti-pilling cationic dyeable polyester chip product.

Example 2:

the embodiment provides a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip, which comprises the following steps:

s1, feeding 100kg of PET recovered raw materials into a mixer, adding 5kg of MEG, stirring uniformly, then feeding the mixture into a screw extruder 1, enabling the materials to pass through the screw extruder 1 provided with a filter screen (F0) 3 under the conditions of 275 ℃ and high pressure, enabling the materials to enter an alcoholysis reaction kettle 2 for reaction with alcoholysis mother liquor, pumping 35kg of MEG from the bottom of the alcoholysis reaction kettle 2 after 60 minutes, stirring and cooling to 180 ℃, and carrying out further alcoholysis for 180 minutes to react to the required alcoholysis degree;

s2, pressing an alcoholysis product of the S1 into a filter (F1) 4 through high-pressure nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis solution diversion kettle 5, adding an antioxidant and a stabilizer, uniformly dividing the alcoholysis solution into two parts, returning one part of the alcoholysis solution to the alcoholysis reaction kettle 2 to serve as alcoholysis mother solution for the next reaction, and enabling the other part of the alcoholysis solution to enter a modification reaction kettle 6 to be modified: adding 10kg of MEG and 30g of silicon dioxide at normal temperature, stirring and heating the mixture to 200 ℃, and then respectively adding 2.6kg of tri-monomer and 1.0kg of tetra-monomer under the protection of nitrogen through a multi-way feeding pipe 7, wherein the tri-monomer is isophthalic acid-5-sodium sulfonate, the tetra-monomer is PEG with the molecular weight of 2000, stirring uniformly and preserving heat for 30 minutes to obtain a modified esterified substance;

s3, enabling the modified esterified substance to enter a polycondensation kettle 9 after passing through a filter (F2) 8, and vacuumizing through a vacuum system to perform a prepolymerization reaction, wherein the prepolymerization reaction temperature is 265 ℃, and the vacuum degree is 0.8KPa; after the prepolymerization reaction is finished, closing a vacuum system, and adding 0.2kg of prepared anti-pilling agent powder into a polycondensation kettle 9 through a feeder 10 under the protection of nitrogen and negative pressure; finally, carrying out final polymerization at the temperature of 280 ℃ and the pressure of 100Pa, discharging and granulating after the final polymerization is finished, and obtaining 102.2kg of the circularly regenerated anti-pilling cationic dyeable polyester chip product.

Example 3:

the embodiment provides a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip, which comprises the following steps:

s1, feeding 100kg of PET recovered raw materials into a mixer, adding 5kg of MEG, stirring uniformly, then feeding into a screw extruder 1, enabling the materials to pass through the screw extruder 1 and a filter screen (F0) 3 under the conditions of 280 ℃ and high pressure, enabling the materials to enter an alcoholysis reaction kettle 2 for reaction with alcoholysis mother liquor, pumping 25kg of MEG from the bottom of the alcoholysis reaction kettle 2 after 45 minutes, stirring, cooling to 200 ℃ and further carrying out alcoholysis for 120 minutes.

S2, pressing an alcoholysis product of the S1 into a filter (F1) 4 through high-pressure nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis liquid diversion kettle 5, uniformly dividing the alcoholysis liquid into two parts, returning one part of alcoholysis liquid as alcoholysis mother liquid into the alcoholysis reaction kettle 2, and enabling the other part of alcoholysis liquid to enter a modification reaction kettle 6 for modification: adding 5kg of MEG at normal temperature to cool the mixture to 200 ℃ and keep the temperature, and then respectively adding 3.0kg of tri-monomer and 1.5kg of tetra-monomer under the protection of nitrogen through a multi-way feeding pipe 7, wherein the tri-monomer is sodium m-phthalate-5-sulfonate, the tetra-monomer is PEG with molecular weight of 4000, stirring and keeping the temperature for 30 minutes to obtain a modified esterified substance;

s3, enabling the modified esterified substance to enter a polycondensation kettle 9 after passing through a filter (F2) 8, and vacuumizing through a vacuum system to perform a prepolymerization reaction, wherein the prepolymerization reaction temperature is 270 ℃, and the vacuum degree is 1.0KPa; after the prepolymerization reaction is finished, closing a vacuum system, and injecting liquid or molten anti-pilling agent under the protection of nitrogen and under negative pressure, and stirring and mixing, wherein the adding amount of the anti-pilling agent is 0.3kg; finally, carrying out final polymerization at the temperature of 285 ℃ and the pressure of 100Pa, discharging and granulating after the final polymerization is finished, and obtaining 102.9kg of the circularly regenerated anti-pilling cationic dyeable polyester chip product.

Example 4:

the embodiment provides a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip, which comprises the following steps:

s1, feeding 100kg of PET recovered raw materials into a mixer, adding 10kg of MEG, uniformly stirring, and then feeding into a screw extruder 1, so that the materials pass through the screw extruder 1 and a filter screen (F0) 3 at 275 ℃ and under a high-pressure environment; then the materials enter an alcoholysis reaction kettle 2 to react with alcoholysis mother liquor, 15kg of MEG is pumped from the bottom of the alcoholysis reaction kettle 2 after 30 minutes, and the mixture is stirred for 90 minutes at 220 ℃ to perform further alcoholysis and react to the required alcoholysis degree;

s2, pressing an alcoholysis product of the S1 into a filter (F1) 4 through high-pressure nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis liquid diversion kettle 5, uniformly dividing the alcoholysis liquid into two parts, returning one part of alcoholysis liquid as alcoholysis mother liquid into the alcoholysis reaction kettle 2, and enabling the other part of alcoholysis liquid to enter a modification reaction kettle 6 for modification: adding 10kg of MEG at normal temperature to cool the mixture to 200 ℃ and keep the temperature, then respectively adding 2.7kg of tri-monomer and 0.5kg of tetra-monomer under the protection of nitrogen through a multi-way feeding pipe 7, wherein the tri-monomer is dimethyl isophthalate-5-sulfonic acid, the tetra-monomer is polyethylene glycol adipate (PEA 10) with a hydroxyl value of 110mgKOH/g, stirring and keeping the temperature for 30 minutes to obtain a modified esterified product;

s3, enabling the modified esterified substance to enter a polycondensation kettle 9 after passing through a filter (F2) 8, and vacuumizing through a vacuum system to perform a prepolymerization reaction, wherein the prepolymerization reaction temperature is 260 ℃, and the vacuum degree is 0.6KPa; after the prepolymerization reaction is finished, closing a vacuum system, adding 0.1kg of prepared anti-pilling agent powder into a polycondensation kettle 9 through a feeder 10 under the protection of nitrogen and negative pressure, and stirring and mixing; finally, carrying out final polymerization at the temperature of 275 ℃ and the pressure of 100Pa, discharging and granulating after the final polymerization is finished, and obtaining 101.3kg of circularly regenerated anti-pilling cationic dyeable polyester chip product.

Example 5:

the embodiment provides a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip, which comprises the following steps:

s1, feeding 100kg of PET recovered raw materials into a mixer, adding 5kg of MEG, stirring uniformly, then feeding into a screw extruder 1, enabling the materials to pass through the screw extruder 1 and a filter screen (F0) 3 under the conditions of 275 ℃ and high pressure, enabling the materials to enter an alcoholysis reaction kettle 2 for reacting with alcoholysis mother liquor for 30 minutes, pumping 35kg of MEG from the bottom of the alcoholysis reaction kettle 2, stirring and cooling to 180 ℃, and carrying out further alcoholysis for 180 minutes to react to the required alcoholysis degree; the method comprises the steps of carrying out a first treatment on the surface of the

S2, pressing an alcoholysis product of the S1 into a filter (F1) 4 through high-pressure nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis liquid diversion kettle 5, uniformly dividing the alcoholysis liquid into two parts, returning one part of alcoholysis liquid as alcoholysis mother liquid into the alcoholysis reaction kettle 2, and enabling the other part of alcoholysis liquid to enter a modification reaction kettle 6 for modification: stirring and heating the mixture to 200 ℃, then respectively adding 2.9kg of tri-monomer and 1.0kg of tetra-monomer under the protection of nitrogen through a multi-way feeding pipe 7, wherein the tri-monomer is dimethyl isophthalate-5-sodium sulfonate, the tetra-monomer is polyethylene glycol adipate (PEA 15) with the hydroxyl value of 80mgKOH/g, stirring uniformly and preserving heat for 30 minutes to obtain a modified esterified substance;

s3, enabling the modified esterified substance to enter a polycondensation kettle 9 after passing through a filter (F2) 8, and vacuumizing through a vacuum system to perform a prepolymerization reaction, wherein the prepolymerization reaction temperature is 265 ℃, and the vacuum degree is 0.8KPa; after the prepolymerization reaction is finished, closing a vacuum system, and adding 0.2kg of prepared anti-pilling agent powder into a polycondensation kettle 9 through a feeder 10 under the protection of nitrogen and negative pressure; finally, carrying out final polymerization at the temperature of 280 ℃ and the pressure of 100Pa, discharging and granulating after the final polymerization is finished, and obtaining 102.1kg of the circularly regenerated anti-pilling cationic dyeable polyester chip product.

Example 6:

the embodiment provides a preparation method of a cyclic regenerated anti-pilling cationic dyeable polyester chip, which comprises the following steps:

s1, feeding 100kg of PET recovered raw materials into a mixer, adding 5kg of MEG, stirring uniformly, then feeding into a screw extruder 1, enabling the materials to pass through the screw extruder 1 and a filter screen (F0) 3 under the conditions of 280 ℃ and high pressure, enabling the materials to enter an alcoholysis reaction kettle 2 to react with alcoholysis mother liquor for 30 minutes, pumping 25kg of MEG from the bottom of the alcoholysis reaction kettle 2, stirring and cooling to 200 ℃ for further alcoholysis for 120 minutes.

S2, pressing an alcoholysis product of the S2 into a filter (F1) 4 through high-pressure nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis liquid diversion kettle 5, uniformly dividing the alcoholysis liquid into two parts, returning one part of alcoholysis liquid as alcoholysis mother liquid into the alcoholysis reaction kettle 2, and enabling the other part of alcoholysis liquid to enter a modification reaction kettle 6 for modification: adding 5kg of MEG at normal temperature to cool the mixture to 200 ℃ and keep the temperature, then respectively adding 3.0kg of tri-monomer and 1.5kg of tetra-monomer under the protection of nitrogen through a multi-way feeding pipe 7, wherein the tri-monomer is isophthalic acid-5-sodium sulfonate, the tetra-monomer is polyethylene glycol adipate (PEA 20) with a hydroxyl value of 50mgKOH/g, stirring and keeping the temperature for 30 minutes to obtain a modified esterified product;

s3, enabling the modified esterified substance to enter a polycondensation kettle 9 after passing through a filter (F2) 8, and vacuumizing through a vacuum system to perform a prepolymerization reaction, wherein the prepolymerization reaction temperature is 270 ℃, and the vacuum degree is 1.0KPa; after the prepolymerization reaction is finished, closing a vacuum system, and injecting liquid or molten anti-pilling agent under the protection of nitrogen and under negative pressure, and stirring and mixing, wherein the adding amount of the anti-pilling agent is 0.3kg; finally, carrying out final polymerization at the temperature of 285 ℃ and the pressure of 100Pa, discharging and granulating after the final polymerization is finished, and obtaining 102.8kg of the circularly regenerated anti-pilling cationic dyeable polyester chip product.

Comparative example:

s1, putting 100kg of treated PET recovery raw materials, 300kg of ethylene glycol, a stabilizer, an antioxidant, a catalyst and the like into an alcoholysis reaction kettle 2, heating to 220 ℃ under the coverage of nitrogen, starting a stirrer, rapidly heating to 255 ℃, maintaining the temperature for 6 hours, heating to 260 ℃, and continuously stirring for 30-60 minutes to obtain an alcoholysis esterified product.

S2, pressing the alcoholysis esterified substance obtained in the step S1 into a modification reaction kettle 6 through a filter (F1) 4, adding 25kg of MEG at normal temperature to cool the mixture to 200 ℃ and keeping the mixture, then respectively adding 3.0kg of a tri-monomer, 1.5kg of a tetra-monomer and 30g of an anti-pilling agent under the protection of nitrogen through a multi-way feeding pipe 7, wherein the tri-monomer is sodium isophthalic acid-5-sulfonate, the tetra-monomer is polyethylene glycol adipate (PEA 20) with a hydroxyl value of 50mgKOH/g, the anti-pilling agent is diphenyl silicon glycol, stirring and keeping the temperature for 30 minutes to obtain a modified esterified substance;

s3, allowing the modified esterified product to enter a polycondensation kettle 9 after passing through a filter (F2) 8, heating to 285 ℃, vacuumizing to 100Pa, performing polymerization reaction, discharging and granulating after the polymerization reaction reaches a set current, and obtaining 101.5kg of product.

The specific parameters of the various embodiments of the present invention are shown in Table 1:

table 1: formula and product index

From this, it can be seen that the DEG content in each example of the present invention is significantly lower than that in the comparative example, i.e., the residual DEG is significantly smaller, indicating that the reaction degree is higher and the purity of the product is improved.

Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present invention, which is intended to be covered by the scope of the claims of the present invention.

Claims (13)

1. The preparation method of the circularly regenerated anti-pilling cationic dyeable polyester chip is characterized by comprising the following steps of:

s1, performing label removal on a recovered PET polyester material, crushing the recovered PET polyester material into square small pieces with the size of 0.5-2.0cm by using a crusher, immersing the square small pieces in hot water, adding a stripping agent and a PET cleaning agent for stirring and cleaning, and repeatedly cleaning the square small pieces with clear water until no PET recovered raw material exists;

s2, preparing alcoholysis mother liquor: putting the treated PET recovered raw material, glycol and catalyst into an alcoholysis reaction kettle, heating to 220 ℃ under the coverage of nitrogen, starting a stirrer, quickly heating to 255 ℃, keeping the temperature for 5-6 hours, heating to 260 ℃ and continuously stirring for 30-60 minutes, and then cooling to 220 ℃;

s3, putting the PET recovery raw material into a high-speed mixer, adding ethylene glycol accounting for 5-10% of the PET recovery raw material, a stabilizer and an antioxidant, uniformly stirring, then feeding into a screw extruder, enabling the material to be melt extruded through the screw extruder at 270-290 ℃ and in a high-pressure environment, enabling the tail end of the screw extruder to be provided with a filter screen F0, enabling the extruded melt to enter an alcoholysis reaction kettle through a melt pipe to react with alcoholysis mother liquor for 30-60 minutes, then pumping MEG accounting for 15-35% of the PET recovery raw material from the bottom of the alcoholysis reaction kettle, and keeping the temperature of 180-220 ℃ for further alcoholysis for 2-4 hours to reach the required alcoholysis degree;

s4, pressing an alcoholysis product of the S3 into a filter F1 through high-pressure nitrogen, enabling the filtered alcoholysis product to enter an alcoholysis liquid diversion kettle, uniformly dividing alcoholysis liquid into two parts, returning one part of alcoholysis liquid as alcoholysis mother liquid into the alcoholysis reaction kettle, and enabling the other part of alcoholysis liquid to enter a modification reaction kettle for modification: adding normal-temperature MEG with the mass of 0-10% of the PET recovery raw material, conducting further alcoholysis for 30-60 minutes, then respectively adding a tri-monomer with the weight of 2.4-3.3% of the PET recovery raw material and a tetra-monomer with the weight of 0.5-1.5% of the PET recovery raw material and a slip agent through a multi-way feeding pipe under the protection of nitrogen, and stirring for 30 minutes at the temperature of 230-240 ℃ to obtain a modified esterified substance;

s5, pressing the modified esterified substance into a polycondensation kettle through a filter F2 by high-pressure nitrogen, vacuumizing by a vacuum system to perform a prepolymerization reaction, wherein the reaction set temperature is 260-275 ℃, and the vacuum degree is 0.6-2.0KPa; starting a vacuum system, gradually establishing vacuum, maintaining for 20-40 minutes after reaching the target vacuum degree, and closing the vacuum system after the prepolymerization reaction is finished; under the protection of nitrogen and negative pressure, adding the prepared anti-pilling agent powder into a polycondensation kettle through a feeder, and stirring and mixing for 5-10 minutes, wherein the adding amount of the anti-pilling agent is 0.15-0.25% of the weight of the PET recovered raw material; finally, carrying out final polycondensation reaction at 270-285 ℃ and under 40-100Pa, discharging and granulating after the final polycondensation reaction is finished, and obtaining the cyclic regenerated anti-pilling cationic dyeable polyester chip product.

2. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: and the step S2, the step S3 and the step S4 are also added with a stabilizer, an antioxidant and a slip agent, wherein the addition amount of the stabilizer and the antioxidant is 0.2-0.8 per mill of the weight of the regenerated recycled material.

3. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 2, wherein the method comprises the following steps: the antioxidants in the steps S2, S3 and S4 are hindered phenol antioxidants, the stabilizer is hindered amine light stabilizer, the slip agent is silicon dioxide, and preferably the film opening agent silicon dioxide with the particle size smaller than 5 mu.

4. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the preparation method of the anti-pilling agent powder in the step S5 comprises the following steps: a closed reaction kettle with a distillation tower and a tower top condenser is filled with the liquid according to the following formula 3:1:4, adding MEG, diphenyl dihydroxysilane (DHDPS) and dimethyl terephthalate (DMT) according to the proportion, heating to 140 ℃, then heating, starting stirring, gradually heating to 220 ℃ within 3 hours, heating to 280 ℃ after methanol is not distilled, vacuumizing until the pressure is lower than 100Pa, reacting for 60-90 minutes, discharging, cooling, and crushing to obtain the anti-pilling agent.

5. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the three monomers in the step S4 are dimethyl isophthalate-5-sodium Sulfonate (SIPM) or isophthalic acid-5-sodium Sulfonate (SIPA) or diethylene glycol isophthalate-5-Sodium Sulfonate (SSIPA), and the added weight is converted by SIPA.

6. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the four monomers in the step S4 are polyethylene glycol (PEG) with molecular weight between 600 and 4000.

7. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the tetrabonomer in the step S4 may also be an ethylene glycol adipate oligomer having a hydroxyl value of 50-110 mgKOH/g.

8. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the hot water temperature in the step S1 is more than 90 ℃, preferably more than 95 ℃, and the water content of the dehydrated PET recovered raw material is not more than 4 per mill.

9. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: in the step S2, part of MEG may be injected at a high pressure from the middle of the extruder during the extrusion and melting process of the material by the screw extruder.

10. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the filtering precision of the filters F0, F1 and F2 in the steps S3, S4 and S5 is 48-150 mu m, 5-25 mu m and 15-30 mu m respectively.

11. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: when the polyester chip product is used for spinning long fibers, the addition amount of the anti-pilling agent is 0.1-0.25% of the weight of the PET recovery raw material; when the anti-pilling agent is used for spinning short fibers, the addition amount of the anti-pilling agent is 0.2-0.5% of the weight of the PET recovery raw material, and the anti-pilling agent is diphenyl dihydroxy silane.

12. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the catalyst in the step S2 refers to zinc acetate or manganese acetate or a mixture of the zinc acetate and the manganese acetate, and the concentration of the catalyst is not more than 200ppm.

13. The method for preparing the circularly regenerated anti-pilling cationic dyeable polyester chip as claimed in claim 1, wherein the method comprises the following steps: the stripping agent in the step S1 adopts long-chain alkyl quaternary ammonium salt, and the adding amount is 30-100ppm.

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