Regenerated polyester staple fiber and production process thereof

Abstract

The invention relates to the technical field of textile, and particularly discloses regenerated polyester staple fibers and a production process thereof. The regenerated polyester staple fiber comprises the following raw materials in parts by weight: 30-40 parts of a regenerated polyester mixture, 10-20 parts of essence microcapsules and 5-15 parts of a polysaccharide modifier, the regenerated polyester mixture comprises the following raw materials in parts by weight: 70-90 parts of polyester waste, 20-30 parts of an alcoholysis agent, 0.5-1 part of an alcoholysis catalyst, 1-3 parts of a decolorizing agent and 0.5-1 part of a polycondensation catalyst; according to the method, the polyester waste is subjected to alcoholysis, then decoloration and polycondensation are performed to form the regenerated polyester mixture with high strength, and then the regenerated polyester mixture is combined with the essence microcapsules and the polysaccharide modifier, so that the regenerated polyester staple fiber prepared by weaving has good strength, whiteness and fragrance holding effect.

Description

Technical Field

[0001] The present application relates to the field of textile technology, and in particular to a regenerated polyester staple fiber and a production process thereof. Background Art

[0002] The global textile industry is facing problems such as high resource consumption and serious environmental pollution. In particular, the production and use of traditional polyester textiles generates a large amount of waste and waste textiles, which are difficult to degrade and cause a serious ecological burden. In recent years, with the increase of environmental awareness, the recycling and reuse of waste polyester textiles has received widespread attention due to its sustainability.

[0003] The recycling methods of waste polyester textiles include energy recovery, physical recovery and chemical recovery. The energy recovery method is a way to recycle the heat energy released during the incineration of waste textiles, but incineration produces a large amount of harmful and toxic gases, which is not friendly to the environment. The physical recovery method refers to the process of reprocessing waste textiles into secondary raw materials or products through physical means. Recycled PET can only be used to produce low-quality secondary products, which is a downgraded recycling. The quality of the recycled products is poor and cannot meet people's requirements for the comfort of textile products.

[0004] The chemical recycling method uses various chemical reactions to depolymerize polymers into monomers, and then separates, purifies, and repolymerizes to achieve closed-loop recycling of PET, which has the characteristics of high recovery rate and high product purity. However, it is more suitable for the recycling of polyester waste yarns with higher purity, and cannot be applied to the recycling of colored waste polyester textiles with mixed components. At the same time, most of them need to be carried out under high temperature and high pressure or acid-base conditions. The reaction conditions are relatively harsh, and the recycled polyester products produced have a pungent chemical solvent smell and reduced texture. Summary of the invention

[0005] In order to better recycle waste polyester textiles, the present application provides a regenerated polyester staple fiber and a production process thereof.

[0006] In the first aspect, the present application provides a regenerated polyester staple fiber, which adopts the following technical solution: A regenerated polyester staple fiber comprises the following raw materials in parts by weight: 30-40 parts of a regenerated polyester mixture, 10-20 parts of flavor microcapsules, and 5-15 parts of a polysaccharide modifier; the regenerated polyester mixture comprises the following raw materials in parts by weight: 70-90 parts of polyester waste, 20-30 parts of an alcoholysis agent, 0.5-1 part of an alcoholysis catalyst, 1-3 parts of a decolorizing agent, and 0.5-1 part of a polycondensation catalyst.

[0007] By adopting the above technical scheme, alcoholysis of polyester waste using alcoholysis agent and alcoholysis catalyst in advance can promote the breakage of polyester molecular chain to form oligomers, and at the same time use decolorizer to decolorize colored complex textile waste to improve the whiteness and color uniformity of regenerated fiber, and finally use polycondensation catalyst to carry out polycondensation reaction to promote the prepared polyester recycled mixture to have good strength and chroma. Fragrance microcapsules can give regenerated polyester staple fiber a lasting fragrance, prolong the persistence of regenerated fiber fragrance, reduce the loss of conventional fragrance during processing, and improve the fragrance and comfort of regenerated polyester staple fiber. The polysaccharide molecules in the polysaccharide modifier can react chemically with the active groups on the surface of polyester fiber to form covalent bonds or hydrogen bonds, thereby improving the hydrophilicity and biocompatibility of the fiber surface, improving the hydrophilicity, antibacterial and biodegradability of regenerated polyester staple fiber, and improving the comfort of regenerated polyester staple fiber.

[0008] Preferably, the alcoholysis agent is ethylene glycol, the alcoholysis catalyst is potassium carbonate, and the polycondensation catalyst is ethylene glycol antimony.

[0009] Preferably, the decolorizing agent is a citric acid-sodium hydroxide buffer solution.

[0010] By adopting the above technical solution, the citric acid-sodium hydroxide buffer solution can effectively remove the pigments carried by the polyester waste, improve the whiteness and color uniformity of the regenerated fiber, and stabilize the pH value of the alcoholysis reaction system, which can promote the alcoholysis reaction of the polyester waste, improve the alcoholysis efficiency and the strength of the regenerated fiber. On the other hand, compared with conventional sodium hypochlorite-based oxidative decolorizing agents or activated carbon-based adsorptive decolorizing agents, the citric acid-sodium hydroxide buffer solution has a better environmental protection effect and can reduce the impact on the environment.

[0011] Preferably, the pH of the citric acid-sodium hydroxide buffer solution is 6-7.5.

[0012] Preferably, the polysaccharide modifier is at least one of microcrystalline cellulose, seaweed polysaccharide, starch and cyclodextrin.

[0013] By adopting the above technical solution, microcrystalline cellulose, seaweed polysaccharide, starch, and cyclodextrin as polysaccharide modifiers can improve the hygroscopicity and air permeability of regenerated polyester staple fibers, make the regenerated polyester staple fibers more suitable for textiles, and improve the comfort and hydrophilicity of the regenerated polyester staple fibers. The polysaccharide modifier can improve the spinnability and dyeability of the fiber, reduce the static electricity phenomenon during the processing, and improve the strength and toughness of the regenerated polyester staple fibers. At the same time, seaweed polysaccharides have natural antibacterial properties, which can inhibit bacterial growth and improve the safety of the regenerated polyester staple fibers.

[0014] Preferably, the flavor microcapsule raw material includes a core material, a first capsule material and a second capsule material, the core material is flavor essential oil, the first capsule material and the second capsule material are both resin capsule materials, and the first capsule material pre-coats the core material.

[0015] By adopting the above technical solution, the essential oil is wrapped by a double-layer resin capsule material to form a tiny particle essence microcapsule, which can inhibit the volatilization loss of the essence, control the release rate, and prolong the fragrance holding time of the recycled polyester staple fiber.

[0016] Preferably, the first capsule material is low-methyl etherified melamine resin prepolymer, and the second capsule material is polyvinyl acetal resin.

[0017] By adopting the above technical scheme, low-methyl etherified melamine resin prepolymer is used as the first capsule material to encapsulate the flavor. Compared with conventional melamine resin, low-methyl etherified melamine resin prepolymer has better dispersibility and higher coverage rate, better emulsion stability, and can be fully polymerized and solidified, thereby improving the coating effect on the flavor. The core material is first coated with low-methyl etherified melamine resin prepolymer, and the heat resistance of low-methyl etherified melamine resin prepolymer can be used to form spherical particles with small and uniform particle size, and then polyvinyl alcohol acetal resin is used for the second layer of coating, and the sealing property of polyvinyl alcohol acetal resin microcapsules and good compatibility with recycled polyester staple fibers can be used to make up for the problem of insufficient fragrance retention of single low-methyl etherified melamine resin prepolymer, so that the prepared flavor microcapsules have higher heat resistance, and the prepared microcapsule particles are uniform, have good compatibility, and have good sustained release effect.

[0018] Preferably, the method for preparing the essence microcapsule comprises the following specific steps: The essence is emulsified in advance to form an essence emulsion, the essence emulsion is mixed with a low-methyl ether melamine resin prepolymer, and then the pH is adjusted to acidic with hydrochloric acid, the temperature is raised to 40-60°C for reaction, an amine cross-linking agent is added dropwise for heat preservation and curing, and the temperature is cooled by stirring to obtain a semi-finished essence microcapsule; polyvinyl alcohol is swelled to prepare a polyvinyl alcohol solution, the semi-finished essence microcapsule is mixed with the polyvinyl alcohol solution, hydrochloric acid is added dropwise to adjust the pH to acidic, an aldehyde cross-linking agent is continued to be slowly added dropwise, the temperature is raised to 40-50°C for reaction, and then sodium hydroxide is used to adjust the pH to neutral, and the temperature is cooled and filtered to obtain the essence microcapsule.

[0019] In a second aspect, the present application provides a production process for regenerated polyester staple fibers, which adopts the following technical solution: A production process for regenerated polyester staple fibers comprises the following specific steps: S1: washing and crushing the polyester waste, mixing the crushed polyester waste, alcoholysis catalyst and alcoholysis agent, heating to 240-250°C for reaction under the protection of nitrogen, filtering and mixing the filtrate with a decolorizing agent and a polycondensation catalyst, reacting at 260-280°C and a vacuum degree of 60-80Pa to obtain a recycled polyester mixture; S2: The recycled polyester mixture, the flavor capsule and the polysaccharide modifier are mixed, melt-blended, extruded into granules, and then melt-spun to obtain primary fibers, and the primary fibers are subjected to air drafting to obtain regenerated polyester staple fibers.

[0020] By adopting the above technical scheme, less alcoholysis agent is used to recycle polyester waste, the use of a large amount of chemical solvents is reduced, the dye in the polyester waste is removed by decolorization technology, and then filtration and purification are used to remove impurities. Finally, polycondensation is used to improve the strength of the recycled polyester to meet the spinning requirements. The recycled polyester mixture is subsequently combined with flavor microcapsules and polysaccharide modifiers to promote the prepared regenerated polyester staple fibers to have a lasting fragrance, high comfort and hydrophilicity, and a short preparation process is used to achieve high-quality recycling of polyester waste.

[0021] Preferably, the melt granulation temperature is 240-270°C, and the melt spinning temperature is 260-280°C.

[0022] In summary, this application has the following beneficial effects: 1. Since the present application uses alcoholysis agent and alcoholysis catalyst to alcoholyze polyester waste, then uses decolorizer to improve the whiteness and color uniformity of the regenerated fiber, and uses polycondensation catalyst to carry out polycondensation reaction, the prepared regenerated polyester mixture has higher strength. The regenerated polyester mixture is combined with essence microcapsules and polysaccharide modifiers, so that the prepared regenerated polyester staple fibers have better strength, comfort and fragrance retention effects.

[0023] 2. In this application, the essential oil is encapsulated by a double-layer resin capsule to form a micro-particle essence microcapsule, which can inhibit the volatilization loss of the essence and prolong the fragrance holding time of the recycled polyester staple fiber. The low-methyl etherified melamine resin prepolymer is used as the first capsule material to encapsulate the essence, and then the polyvinyl alcohol acetal resin is used for the second layer coating, so that the prepared essence microcapsule has higher heat resistance, and the prepared microcapsule particles are uniform, have good compatibility, and have a good sustained release effect. DETAILED DESCRIPTION

[0024] The present application is further described in detail below with reference to the embodiments.

[0025] All raw materials in the examples are commercially available.

[0026] Preparation example of recycled polyester blend Preparation Example 1 The recycled polyester mixture includes the following raw materials in parts by weight: 80 kg of polyester waste, 25 kg of alcoholysis agent, 0.8 kg of alcoholysis catalyst, 2 kg of decolorizing agent, and 0.8 kg of polycondensation catalyst, wherein the alcoholysis catalyst is potassium carbonate, the alcoholysis agent is ethylene glycol, the polycondensation catalyst is ethylene glycol antimony, the decolorizing agent is citric acid-sodium hydroxide buffer solution, and the pH value of the citric acid-sodium hydroxide buffer solution is 7.

[0027] The preparation method of the recycled polyester mixed material comprises the following specific steps: The polyester waste is washed and crushed, and the crushed polyester waste, alcoholysis catalyst and alcoholysis agent are mixed, and the temperature is raised to 245°C under the protection of nitrogen for reaction for 4 hours to obtain alcoholysis solution, and the alcoholysis solution is filtered and the filtrate is taken, and the filtrate is mixed with the decolorizing solution and the condensation catalyst, and the reaction is carried out at 270°C and a vacuum degree of 70Pa for 50 minutes to obtain a recycled polyester mixture.

[0028] Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that the amount of polyester waste used in the recycled polyester mixed material is 70 kg, the amount of alcoholysis agent used is 30 kg, the amount of alcoholysis catalyst used is 1 kg, the amount of decolorizing agent used is 1 kg, and the amount of condensation catalyst used is 0.5 kg.

[0029] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that the amount of polyester waste used in the recycled polyester mixed material is 90 kg, the amount of alcoholysis agent used is 20 kg, the amount of alcoholysis catalyst used is 0.5 kg, the amount of decolorizing agent used is 3 kg, and the amount of condensation catalyst used is 1 kg.

[0030] Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that the decolorizing agent in the recycled polyester mixed material is sodium hypochlorite. Example

[0031] Example 1 This embodiment provides a regenerated polyester staple fiber, comprising the following raw materials in parts by weight: 35 kg of regenerated polyester mixture, 15 kg of flavor microcapsules, and 10 kg of polysaccharide modifier; wherein the regenerated polyester mixture is from Preparation Example 1, the polysaccharide modifier is seaweed polysaccharide, and the flavor microcapsule raw materials include a core material and a first capsule material, wherein the core material is lavender essential oil, and the first capsule material is melamine resin prepolymer. The melamine resin prepolymer is purchased from Beijing Letai Chemical Supermarket.

[0032] The production process of recycled polyester staple fiber includes the following specific steps: S1: Mix lavender essential oil, Tween 80 and water in a mass ratio of 1:0.8:50, stir evenly to form an essence emulsion, mix the essence emulsion with melamine resin prepolymer, add hydrochloric acid to adjust the pH to 4, add ammonium chloride, the mass ratio of ammonium chloride to melamine resin prepolymer is 0.1:1, heat to 50°C and keep warm for 3 hours, cool down and use 30% sodium hydroxide solution to adjust the pH of the reaction system to 7, cool down and filter and dry to obtain essence microcapsules.

[0033] S2: The recycled polyester mixture, flavor capsules and polysaccharide modifier are mixed, melt-blended at 260°C, extruded into granules, and then melt-spun at 270°C to obtain spun fibers. The spun fibers are subjected to air drafting, curling and drying to obtain regenerated polyester staple fibers.

[0034] Example 2 The difference between Example 2 and Example 1 is that the amount of the recycled polyester mixture in the recycled polyester staple fiber raw material is 30 kg, the amount of the flavor microcapsule is 20 kg, and the amount of the polysaccharide modifier is 5 kg.

[0035] Example 3 The difference between Example 3 and Example 1 is that the amount of the recycled polyester mixture in the recycled polyester staple fiber raw material is 40 kg, the amount of the flavor microcapsule is 10 kg, and the amount of the polysaccharide modifier is 15 kg.

[0036] Example 4 The difference between Example 4 and Example 1 is that the regenerated polyester blend in the regenerated polyester staple fiber raw material comes from Preparation Example 2.

[0037] Example 5 The difference between Example 5 and Example 1 is that the regenerated polyester blend in the regenerated polyester staple fiber raw material comes from Preparation Example 3.

[0038] Example 6 The difference between Example 6 and Example 1 is that the regenerated polyester blend in the regenerated polyester staple fiber raw material comes from Preparation Example 4.

[0039] Example 7 The difference between Example 7 and Example 1 is that the polysaccharide modifier in the regenerated polyester staple fiber raw material is a mixture of seaweed polysaccharide and starch, and the mass ratio of seaweed polysaccharide to starch is 1:1.

[0040] Example 8 The difference between Example 8 and Example 7 is that the first capsule material of the flavor microcapsule raw material is low-methyl etherified melamine resin prepolymer, and the low-methyl etherified melamine resin prepolymer is purchased from Tianjin Honest Chemical Industry and Trade Co., Ltd. MR-625.

[0041] Example 9 The difference between Example 9 and Example 8 is that the raw materials of the flavor microcapsule include a core material, a first capsule material and a second capsule material, the core material is lavender essential oil, the first capsule material is a low-methyl etherified melamine resin prepolymer, and the second capsule material is a polyvinyl alcohol acetal resin.

[0042] The production process of recycled polyester staple fiber includes the following specific steps: S1: Mix lavender essential oil, Tween 80 and water in a mass ratio of 1:0.8:50, stir evenly to form an essence emulsion, mix the essence emulsion with low methyl ether melamine resin prepolymer, then add hydrochloric acid to adjust the pH to 4, add ammonium chloride, the mass ratio of ammonium chloride to low methyl ether melamine resin prepolymer is 0.1:1, heat to 50°C and keep warm for 3 hours to cure, and cool down to obtain the semi-finished essence microcapsule.

[0043] S2: Mix polyvinyl alcohol with water, the molecular weight of polyvinyl alcohol is 10000, swell at room temperature and stir evenly at 65°C to prepare a polyvinyl alcohol solution with a polyvinyl alcohol concentration of 4%, mix the semi-finished flavor microcapsule with the polyvinyl alcohol solution, add hydrochloric acid to adjust the pH to 2, slowly add glutaraldehyde, the mass ratio of glutaraldehyde to polyvinyl alcohol solution is 0.1:1, heat to 45°C and react for 3h, use 30% sodium hydroxide solution to adjust the pH of the reaction system to 7, cool and filter and dry to obtain flavor microcapsules.

[0044] S3: The recycled polyester mixture, fragrance microcapsules and polysaccharide modifier are mixed, melt-blended at 260°C, extruded into granules, and then melt-spun at 270°C to obtain spun fibers, and the spun fibers are subjected to air drafting, curling and drying to obtain regenerated polyester staple fibers.

[0045] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no fragrance microcapsules and polysaccharide modifiers are used in the regenerated polyester staple fiber raw material.

[0046] The production process of recycled polyester staple fiber includes the following specific steps: The recycled polyester mixture is melt-blended at 260°C, extruded into granules, and then melt-spun at 270°C to obtain nascent fibers. The nascent fibers are subjected to air drafting, curling, and drying to obtain regenerated polyester staple fibers.

[0047] Performance testing The following performance tests were performed on the regenerated polyester staple fibers provided in Examples 1-9 and Comparative Example 1 of the present application, and the specific test results are shown in Table 1.

[0048] Detection Methods 1. Mechanical properties The breaking strength of the regenerated polyester staple fiber prepared in the present application was tested with reference to the standard of GB / T 14337-2008 "Test method for tensile properties of chemical staple fibers".

[0049] 2. Decolorization rate P Firstly, the light reflectance R of polyester waste textile samples at visible light wavelength of 380-750nm was tested by UV-visible spectrophotometer. The scanning speed was medium, the sampling interval was 0.5nm, the slit width was 20nm, and the detection unit was an external dual detector. Then, the ratio of the colorant absorption coefficient K to the colorant scattering coefficient S was calculated by the Kubelka-Munk equation (Formula 1), and then P was calculated by Formula 2.

[0050] Formula 1: K / S = (1-0.01R) 2 / 0.02R; Formula 2: P = (K0-K1) / K0*100%.

[0051] Wherein: K0 represents the K / S value of the polyester waste textile sample before bleaching, and K1 represents the K / S value of the regenerated polyester staple fiber after bleaching.

[0052] 3. Chroma With reference to the standard of GB / T17644-2008 "Test method for whiteness and chromaticity of textile fibers", the whiteness of the regenerated polyester staple fibers prepared in this application was tested, and the fragrance holding time of the regenerated polyester staple fibers was recorded after washing for multiple times.

[0053] Table 1: Performance test results data table From the performance test results, it can be seen that the present application performs alcoholysis on polyester waste and then performs decolorization and polycondensation, and then combines with fragrance microcapsules and polysaccharide modifiers, so that the prepared regenerated polyester staple fibers have good strength, comfort and fragrance-holding effects. By comparing Comparative Example 1 with Example 1, it can be seen that Comparative Example 1 does not use fragrance microcapsules and polysaccharide modifiers. Although the prepared regenerated polyester staple fibers have good strength and decolorization effects, there is still a certain irritating odor due to the use of chemical solvents during processing and use, and the texture is poor, which in turn affects the application of the regenerated polyester staple fibers.

[0054] By comparing Examples 8-9 with Example 1, it can be seen that Example 1 uses a single-layer melamine resin capsule material, Example 8 uses a low-methyl etherified single-layer melamine resin capsule material, and Example 9 uses a double-layer capsule material. The first capsule material is a low-methyl etherified melamine resin prepolymer, and the second capsule material is a polyvinyl alcohol acetal resin. From the performance test results, it can be seen that the regenerated polyester staple fiber prepared in Example 9 has a more lasting aroma and can still maintain a good aroma after multiple washings.

[0055] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A regenerated polyester staple fiber, characterized in that: The recycled polyester mixture comprises the following raw materials in parts by weight: 30-40 parts of recycled polyester mixture, 10-20 parts of flavor microcapsules, and 5-15 parts of polysaccharide modifiers; the recycled polyester mixture comprises the following raw materials in parts by weight: 70-90 parts of polyester waste, 20-30 parts of alcoholysis agent, 0.5-1 part of alcoholysis catalyst, 1-3 parts of decolorizing agent, and 0.5-1 part of polycondensation catalyst.

2. The regenerated polyester staple fiber according to claim 1, characterized in that: The alcoholysis agent is ethylene glycol, the alcoholysis catalyst is potassium carbonate, and the polycondensation catalyst is ethylene glycol antimony.

3. The regenerated polyester staple fiber according to claim 1, characterized in that: The decolorizing agent is a citric acid-sodium hydroxide buffer solution.

4. The regenerated polyester staple fiber according to claim 3, characterized in that: The pH value of the citric acid-sodium hydroxide buffer solution is 6-7.

5.

5. The regenerated polyester staple fiber according to claim 1, characterized in that: The polysaccharide modifier is at least one of microcrystalline cellulose, seaweed polysaccharide, starch and cyclodextrin.

6. The regenerated polyester staple fiber according to claim 1, characterized in that: The essence microcapsule raw material comprises a core material, a first capsule material and a second capsule material. The core material is essence oil, the first capsule material and the second capsule material are both resin capsule materials, and the first capsule material pre-coats the core material.

7. The regenerated polyester staple fiber according to claim 6, characterized in that: The first capsule material is low-methyl etherified melamine resin prepolymer, and the second capsule material is polyvinyl acetal resin.

8. The regenerated polyester staple fiber according to claim 7, characterized in that: The preparation method of the essence microcapsule comprises the following specific steps: The essence is emulsified in advance to form an essence emulsion, the essence emulsion is mixed with a low-methyl ether melamine resin prepolymer, and then the pH is adjusted to acidic with hydrochloric acid, the temperature is raised to 40-60°C for reaction, an amine cross-linking agent is added dropwise for heat preservation and curing, and the temperature is cooled by stirring to obtain a semi-finished essence microcapsule; polyvinyl alcohol is swelled to prepare a polyvinyl alcohol solution, the semi-finished essence microcapsule is mixed with the polyvinyl alcohol solution, hydrochloric acid is added dropwise to adjust the pH to acidic, an aldehyde cross-linking agent is continued to be slowly added dropwise, the temperature is raised to 40-50°C for reaction, and then sodium hydroxide is used to adjust the pH to neutral, and the temperature is cooled and filtered to obtain the essence microcapsule.

9. A process for producing regenerated polyester staple fibers according to any one of claims 1 to 8, characterized in that: The specific steps include: S1: washing and crushing the polyester waste, mixing the crushed polyester waste, alcoholysis catalyst and alcoholysis agent, heating to 240-250°C for reaction under the protection of nitrogen, filtering and mixing the filtrate with a decolorizing agent and a polycondensation catalyst, reacting at 260-280°C and a vacuum degree of 60-80Pa to obtain a recycled polyester mixture; S2: The recycled polyester mixture, the flavor capsule and the polysaccharide modifier are mixed, melt-blended, extruded into granules, and then melt-spun to obtain primary fibers, and the primary fibers are subjected to air drafting to obtain regenerated polyester staple fibers.

10. The production process of regenerated polyester staple fiber according to claim 9, characterized in that: The melt granulation temperature is 240-270°C, and the melt spinning temperature is 260-280°C.

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