A rapid detection method for recycled polyester fibers and application thereof

Abstract

The present application relates to the technical field of fiber identification, and particularly relates to a rapid qualitative and semi-quantitative detection method and application of recycled polyester fiber. The rapid detection method of recycled polyester fiber cuts polyester fiber to be identified into fiber samples; differential scanning calorimetry curve collection: a proper amount of the fiber samples is put into an aluminum crucible and is pressed to be placed in a differential scanning calorimeter, differential scanning calorimetry detection is performed, and the differential scanning calorimetry curve of the fiber sample is recorded; qualitative and semi-quantitative analysis: the differential scanning calorimetry curve is compared with the differential scanning calorimetry curve of a reference sample, the reaction heat absorption peak corresponding to the differential scanning calorimetry curve is analyzed, the qualitative result of the recycled polyester fiber to be identified is determined according to the relative intensity and temperature difference of the reaction heat absorption peak of the fiber sample and the reference sample, and the recycling degree of the recycled polyester fiber is semi-quantitatively determined.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fiber identification, and particularly relates to a rapid qualitative and semi-quantitative detection method and application of recycled polyester fiber. BACKGROUND

[0002] The continuous high-speed growth of the chemical industry and the huge demand for chemical products have led to a serious shortage of raw materials. At the same time, the environmental pollution pressure caused by various types of waste chemical waste is also increasing, and the source of raw materials and waste disposal have become a thorny problem restricting the development of the industry. Establishing a recycling and reuse cycle from waste to raw materials is an effective way to solve the problem.

[0003] In the chemical fiber textile industry, the polyester industry develops the fastest. Polyester (PET, polyethylene terephthalate) is a saturated polyester polymerized from chemical raw materials terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG). Because of its good physical and chemical properties, it is widely used in food packaging, fibers, films, sheet bases and electrical insulation materials. In the PET consumption structure, it mainly accounts for a large proportion in the food packaging industry and the chemical fiber industry, such as soft drink bottles and clothing (also known as polyester). On the one hand, polyester products are chemically stable and not easy to degrade, and the social stock is constantly rising. Although waste polyester does not directly pollute the environment, it will occupy a lot of space. Because of its strong chemical inertness, it is difficult to be degraded by air or microorganisms, and will have a great impact on the environment. Therefore, in recent years, the recycling of waste polyester has been paid increasing attention by countries around the world. The proportion of chemical fiber products represented by polyester fiber in daily life is getting larger and larger. With the increasing shortage and increasing demand for natural resources such as oil, people have begun to turn their attention to the production of recycled polyester fibers, that is, through the reprocessing of virgin polyester products, new recycled products are obtained, which can effectively utilize resources and protect the environment and reduce white pollution. Therefore, seeking the recycling of waste polyester is the only way to sustainable development.

[0004] The source of waste polyester mainly has two parts, one part is the waste materials, leftover materials generated in the production and processing process of polyester fiber. This part of the waste is relatively clean and can be directly reused as raw materials. For example, oligomers can be used for polycondensation and tackification; and films, blocks and yarns can be recycled after regranulation. The other part comes from waste polyester packaging materials, such as polyester bottles and polyester films. This part of the waste often has oil stains and other plastics, or contains other inorganic impurities and other pollutants, which must be purified and separated to remove pollutants and extraneous matter before recycling. The existence of the recycled polyester fiber industry can be said to be a temporary solution to the problem of polyester bottle recycling. The recycled hollow polyester staple fiber produced by chemical fiber using recycled PET beverage bottles and waste polyester textiles as raw materials is a green product of resource regeneration.

[0005] With the development of the regenerated polyester industry, recycled polyester fibers and textiles produced from waste polyester as raw materials have gradually begun to become popular, and the use of recycled polyester fabrics and garments has become a fashion, with huge market development potential. Unlike most virgin polyester products, which are used for spinning and weaving, the use of recycled polyester products shows a clear trend of diversification and is still expanding. Currently, its application market has covered non-woven fabrics, carpets, home textiles, automotive textiles and other fields, and there are nearly 100 types of products.

[0006] Cyclic regenerated fibers are prepared by chemical, physical and other modern technological means combined with spinning processing. Physical method refers to the recycling method of directly melt spinning the waste polyester materials after sorting, cleaning and drying. Chemical method refers to the process of depolymerizing waste polyester materials into polymer monomers or polymer intermediates, and then regenerating polymerization and melt spinning after purification and separation. Compared with the chemical method, the physical method has the characteristics of simple production technology, shorter process flow and lower production cost, so it is the dominant polyester recycling method. More than 70% to 80% of the production capacity of regenerated polyester fibers is recycled by physical method. However, because it belongs to open-loop recycling, the polyester fiber will change with the increase of processing times. The chemical method is growing through equipment and process innovation. At present, an important direction of chemical recycling of waste polyester (PET) is to alcoholysis of waste polyester with ethylene glycol (EG), and then perform transesterification reaction in methanol to generate dimethyl terephthalate (DMT) and ethylene glycol (EG). Pure DMT is obtained by purification and used to regenerate polyester, thereby realizing the recycling of waste polyester.

[0007] Cyclic regenerated fibers can realize the green transformation of the textile industry and are a model of turning waste into treasure. However, for raw material suppliers and consumers, whether a certain polyester fiber is a cyclic regenerated polyester and how many times the cyclic regenerated polyester has been recycled will affect the quality and performance of the polyester. The existing textile industry standards FZ / T 01057-2007 and FZ / T 01057-2012 are based on the principle of determining the type of fiber through combustion method, microscope method, dissolution method, melting point method, density gradient method, etc. The main copolymer units of regenerated polyester (polyester) and virgin polyester (polyester) are the same, and their molecular structures at room temperature are as follows: Figure 1As shown, there is no essential difference in the aggregate structure and physicochemical properties, and it is very difficult to qualitatively identify them. The current standard GB / T 39026-2020 proposes a qualitative identification method for recycled polyester (PET) fibers using high-performance liquid chromatography. This method uses organic solvents, is cumbersome and time-consuming, and requires a large amount of calculation and comparison of experimental data. It is more difficult to identify conventional polyester fiber samples with dyeing and coating. In the face of the upcoming recycled fiber era, it is urgent to develop a fast and efficient, widely applicable, and organic solvent-free or other reagent-free recycled fiber identification method. There is no related report at present, but it is of great significance for future application. SUMMARY

[0008] In view of the above problems, the present application provides a rapid detection method for recycled polyester fibers and its application. The rapid detection method can qualitatively identify virgin polyester fibers and recycled polyester fibers efficiently and quickly, and semi-quantitatively distinguish the recycling engineering degree of recycled polyester fibers. At the same time, for dyed and coated recycled polyester fibers, no other pretreatment or other operation steps are required, which can effectively fill the technical gap in this field.

[0009] To achieve the above-mentioned purpose, in one aspect of the present application, the inventors provide a rapid detection method for recycled polyester fibers, comprising the following steps:

[0010] Fiber sample preparation: cutting the polyester fibers to be identified into fiber samples;

[0011] Differential scanning calorimetry curve acquisition: taking an appropriate amount of the fiber sample into an aluminum crucible and pressing it into a differential scanning calorimeter, performing differential scanning calorimetry detection, and recording the differential scanning calorimetry curve of the fiber sample;

[0012] Qualitative and semi-quantitative analysis: comparing the differential scanning calorimetry curve with the differential scanning calorimetry curve of the reference sample, analyzing the reaction heat absorption peak corresponding to the differential scanning calorimetry curve, and determining the qualitative result of the recycled polyester fibers to be identified as virgin polyester fibers or recycled polyester fibers according to the peak shape, relative intensity, and temperature difference of the reaction heat absorption peak of the fiber sample and the reference sample.

[0013] Differential scanning calorimetry (DSC) is a thermal analysis method. It is an analysis method for measuring the energy difference (or power difference) between a sample and a reference material with respect to temperature change under programmed temperature conditions. Differential scanning calorimetry has two types of compensation and heat flow. In differential scanning calorimetry, in order to keep the temperature difference between the sample and the reference material to zero, the curve of the heat necessary to be applied per unit time with respect to temperature is called differential scanning calorimetry DSC curve, which takes the heat added per unit time (sample heat absorption or heat release rate, i.e. heat flow rate) as the vertical coordinate and takes the temperature or time as the horizontal coordinate. A variety of thermodynamic and kinetic parameters can be measured, such as specific heat capacity, reaction heat, transition heat, phase diagram, reaction rate, crystallization rate, polymer crystallinity, etc. Differential scanning calorimetry is often applied to investigate the properties of the sample material, such as crystal state transition, melting, dehydration, glass transition, compatibility, reaction kinetics, oxidation and degradation, etc. so as to obtain the internal relationship between the thermal changes of the microstructure and the macroscopic thermal properties of the material.

[0014] The conventional use of differential scanning calorimeter includes the following steps:

[0015] 1. Open the gas valve.

[0016] 2. Turn on the refrigerator switch.

[0017] 3. Turn on the instrument power switch.

[0018] 4. Turn on the computer, click the "instrument control icon" on the desktop, double-click the instrument icon, and complete the online connection.

[0019] 5. Set the temperature rising program and atmosphere.

[0020] 6. Weigh a certain amount of sample into the crucible and press the cover.

[0021] 7. Input the sample weight into the control software and adjust the zero point.

[0022] 8. Click Start Test Sample.

[0023] 9. The software can process the curve as required, such as peak marking, select print from the file menu, and print the curve graph in different forms to report.

[0024] 10. Exit the system.

[0025] In the process of exploring the present application, the inventors found that some fiber identification methods in the prior art also use differential scanning calorimetry for identification and quantification, but the objects of identification are different fibers with substantial differences in molecular structure. According to the characteristic that the thermal reaction temperature ranges of different fibers do not overlap, the thermal reaction peak area is integrated, and quantitative results are obtained through multiple mathematical calculations. The present application aims to qualitatively identify virgin polyester fibers and recycled polyester fibers; secondly, on the basis of qualitative identification, to semi-quantitatively distinguish the degree of recycling of recycled polyester fibers. In addition, the technical solution of the present application is also applicable to the qualitative and semi-quantitative distinction of dyed and coated virgin polyester fibers / recycled polyester fibers, and this method has not been reported in research.

[0026] The recycled polyester fiber PET and the virgin polyester fiber PET to be identified in the present application have no essential difference in chemical composition, aggregate structure and physical and chemical properties, and no obvious difference in appearance. The current conventional fiber identification method cannot accurately and efficiently distinguish them. The inventors found that recycled polyester fibers and virgin polyester fibers differ in oligomer content and crystallinity, and the more times the polyester fiber is recycled, the more obvious the difference. This is because the more times the polyester fiber is recycled, the more oligomers are produced in the recycled polyester fiber as the polyester fiber molecules repeat the processes of melting, spinning, depolymerization and repolymerization. The more times the recycled polyester fiber is recycled, the higher the oligomer content in the recycled polyester fiber. Therefore, when the differential scanning calorimeter is detected at a rising temperature, the recycled polyester fiber will have two or more endothermic peaks, indicating the presence of two or more different types of polymers or different crystal forms, which produce reaction heat at different temperatures. According to the principle of different reaction heat of oligomers and main chains in polyester fiber molecules, the inventors collected the reaction heat data of the polyester fiber sample, which was displayed in the form of differential scanning calorimetry DSC curve, to achieve the purpose of qualitative and semi-quantitative identification. And through a large number of practical verification, it was found that this qualitative and semi-quantitative identification is still effective and stable in the case of dyed or coated polyester fibers, and is not affected by pigment molecules and coating molecules.

[0027] The polyester fiber to be identified in the technical solution of the present application is virgin polyester fiber or recycled polyester fiber. The differential scanning calorimetry technology is adopted without the need for complex analysis methods such as mathematical calculation. The differential scanning calorimetry DSC curve of the polyester fiber sample to be identified presents the thermal change of the molecular microstructure. The absorption peak characteristics of the specific reaction heat are compared. According to the comparison result, the polyester fiber sample to be identified is determined and distinguished. Moreover, according to the principle of the change of the oligomer component and content in the molecular structure of the recycled polyester fiber, without using any solution and solvent, the differential scanning calorimetry curve of the polyester fiber after recycling and reuse is widened, the peak number is increased, and the peak is shifted to low temperature, so as to semi-quantitatively determine the degree of recycling and reuse of the polyester fiber. The determination result is simple, intuitive, accurate and efficient. Since the degree of recycling and reuse is too large, the performance of the polyester fiber will change. The present application provides a reference for the detection technology and standard formulation of the related recycled polyester fiber in the future, so as to further support the expansion of different application fields and directions of the polyester fiber with different degrees of recycling and reuse. The present application does not use any additional solvent, and does not need to make any other pretreatment to the polyester fiber to be identified. From the polyester fiber to be identified to the qualitative and semi-quantitative identification result, only about 20 minutes are needed. The method is very efficient, environmentally friendly, stable and accurate, and is suitable for the market subjects and detection institutions of the production, sales, procurement and identification of recycled polyester fiber and its textiles.

[0028] Since the technical solution of the present application aims to efficiently and accurately determine whether the polyester fiber is virgin polyester fiber or recycled polyester fiber, that is, the qualitative and semi-quantitative identification method of the present application is aimed at identifying virgin polyester fiber and recycled polyester fiber. Virgin polyester fiber and recycled polyester fiber have no essential difference in chemical composition, aggregate structure and physical and chemical properties, only differ in oligomer content and crystallinity, etc., so the rapid detection method is preferably used for the virgin polyester fiber and the recycled polyester fiber, but not for other fibers completely different from the virgin polyester fiber and the recycled polyester fiber.

[0029] In some preferred embodiments, the average length of the fiber sample is 0.1-1mm. If the length of the fiber sample is too long, the polyester fibers to be identified are stacked loosely, which is easy to cause uneven heating, and reduces the amount of sample preparation and the differential scanning calorimetry DSC signal.

[0030] In some preferred embodiments, the sample mass used in the differential scanning calorimetry analysis in the differential scanning calorimetry curve collecting step of the fiber sample is 1-5 mg. Such a setting is related to the characteristics of the thermal response of the fiber sample with temperature. If the sample mass is too large, the temperature gradient is formed within the fiber sample due to heat conduction, which deteriorates the resolution of the curve and affects the identification result. If the sample mass is too small, the thermal response signal is weakened, which affects the identification result.

[0031] In some preferred embodiments, the differential scanning calorimetry curve collecting step further comprises a step of heating the differential scanning calorimeter to 500°C after the fiber sample is placed in the aluminum crucible and then placed in the differential scanning calorimeter. The heating rate is not particularly required and can be adjusted to 10-30°C / min or 30-50°C / min. Such a setting is related to the characteristics of the fiber sample to be identified with temperature. If the heating rate is too low, the identification time is prolonged, and the resolution of the heat absorption peak of the reaction heat is reduced, which affects the identification result. If the heating rate is too high, the temperature lag is more serious, the actual temperature of the fiber sample is lower than the programmed temperature of the instrument, and the analysis error is easily caused.

[0032] In some preferred embodiments, the reference sample comprises a virgin polyester fiber reference sample and a recycled polyester fiber reference sample. The differential scanning calorimetry (DSC) curve of the fiber sample is compared with the differential scanning calorimetry (DSC) curve of the reference sample. The endothermic peak intensity at high temperature of the virgin polyester fiber is about one time of the endothermic peak intensity at low temperature, and the temperature interval between the two endothermic peaks at high and low temperatures is within a certain range, under the condition of heating from room temperature to 500°C at a heating rate of 20°C / min and in a N2 atmosphere. The recycled polyester fiber shows different characteristics according to the degree of recycling. For the recycled polyester fiber with a small degree of recycling, the endothermic peak intensity at high temperature is equivalent to or less than the endothermic peak intensity at low temperature, and the temperature interval between the two endothermic peaks at high and low temperatures is slightly larger than that of the virgin polyester fiber. For the recycled polyester fiber with a large degree of recycling, more endothermic peaks or a wider endothermic peak appears, the endothermic peak intensity at low temperature is greater than or equivalent to the endothermic peak intensity at high temperature, and the endothermic peaks at high and low temperatures are both shifted to low temperature compared with the two endothermic peaks of the virgin polyester fiber.

[0033] More preferably, the virgin polyester fiber reference sample includes a black virgin polyester fiber reference sample and a white virgin polyester fiber reference sample. The recycled polyester fiber reference sample includes a white recycled polyester fiber reference sample and a black recycled polyester fiber reference sample. The recycled polyester fiber test sample to be tested includes recycled polyester fibers of various colors such as black, white, orange, purple, yellow, green, etc. and / or recycled polyester fiber test samples with coatings. When the test sample to be tested is a fiber test sample of various colors or with coatings, the white or black recycled polyester fiber reference sample can still be used for comparison. That is, when the polyester fiber test sample to be tested is identified as virgin or recycled and the degree of recycling of the recycled polyester fiber is distinguished, it is not strictly required that the polyester fiber test sample to be tested must be black or white, even if it has been dyed with pigments and / or has coatings, it can still be directly detected without any pretreatment, without removing the pigments or coatings, and the detection result is still accurate, stable and efficient. Therefore, the present application can not only use differential scanning calorimetry to qualitatively identify virgin polyester fibers and recycled polyester fibers, including dyed and coated polyester fiber test samples, but also can combine the qualitative analysis results to make a semi-quantitative theoretical identification of the degree of recycling of the recycled polyester fiber, which is a breakthrough in traditional identification methods.

[0034] Another contribution of the present application is that the identification result is analyzed in combination with the intensity and temperature difference of the reaction heat absorption peak to obtain the identification conclusion. In the qualitative and semi-quantitative analysis step, the heating rate is 10-30℃ / min, if the fiber test sample to be tested has two reaction heat absorption peaks or one very wide reaction heat absorption peak, and both of the two reaction heat absorption peaks are shifted to a lower temperature compared with the high and low temperature reaction heat absorption peaks of the virgin polyester fiber reference sample, it is determined that the fiber test sample to be tested is a recycled polyester fiber; if the fiber test sample to be tested has two reaction heat absorption peaks, and the intensity of the reaction heat absorption peak at high temperature is more than one time greater than the intensity of the reaction heat absorption peak at low temperature, it is determined that the fiber test sample to be tested is a virgin polyester fiber.

[0035] Further, the qualitative determination of the regenerated polyester fiber can also be the following cases: if the fiber sample to be identified has two reaction heat absorption peaks, the intensity of the reaction heat absorption peak at high temperature is equivalent to or less than the intensity of the reaction heat absorption peak at low temperature, and both of the two reaction heat absorption peaks are shifted to low temperature compared with the reaction heat absorption peaks of the virgin polyester fiber reference sample, then it is determined that the fiber test to be identified is a regenerated polyester fiber; or, if the fiber sample to be identified has two reaction heat absorption peaks, the reaction heat absorption peak at low temperature is shifted to low temperature compared with the reaction heat absorption peak at low temperature of the virgin polyester fiber reference sample, and the temperature difference range of the two reaction heat absorption peaks is greater than the temperature difference range of the two reaction heat absorption peaks of the virgin polyester fiber, then it is determined that the fiber test to be identified is a regenerated polyester fiber; or, if the fiber sample to be identified has more than two or a very wide reaction heat absorption peak, and both of the two reaction heat absorption peaks are shifted to low temperature compared with the reaction heat absorption peaks of the virgin polyester fiber reference sample, and the intensity of the reaction heat absorption peak at high temperature is less than the intensity of the reaction heat absorption peak at low temperature, then it is determined that the fiber test to be identified is a regenerated polyester fiber.

[0036] In some other preferred embodiments, in the differential scanning calorimetry curve acquisition step, a step of pre-setting an inert gas atmosphere in the differential scanning calorimeter is further included. The pre-set atmosphere is related to the molecular pyrolysis process of the obtained fiber sample. If the pre-set atmosphere is an oxidizing or reactive gas, the reaction heat process is complex, the differential scanning calorimetry (DSC) curve is deformed, and the identification analysis is affected.

[0037] In another aspect of the present application, the inventors provide an application of the rapid detection method of the first aspect in the qualitative semi-quantitative identification of polyester fibers as virgin polyester fibers or regenerated polyester fibers, wherein the semi-quantitative identification is the determination of the recycling degree of the regenerated polyester fiber.

[0038] The technical scheme is directed to the polyester fiber sample to be identified as virgin polyester fiber or recycled polyester fiber, and can efficiently and accurately determine whether the fiber to be identified is virgin polyester fiber or recycled polyester fiber, and theoretically semi-quantitatively identify the recycling degree of the polyester fiber. The whole identification process does not add other organic solvents, does not need pretreatment, long-time instrument operation and complex mathematical calculation, has the characteristics of more environmental protection, high efficiency and accuracy, provides an innovative fiber identification technical scheme. The polyester fiber sample to be identified does not have special requirements for dyeing or coating processing, has wide applicability, fills the technical blank of recycled polyester fiber identification after dyeing or coating, has good technical support significance for promoting the action initiative of 100% regenerated polyester product, is suitable for vigorous promotion and application in the textile industry, and effectively promotes the development of inspection and detection technology.

[0039] The above invention content is only a summary of the technical scheme of the present application. In order to enable those skilled in the art to more clearly understand the technical scheme of the present application, and then can be implemented according to the content of the description and the drawings, and in order to make the above-mentioned purpose and other purposes, characteristics and advantages of the present application more easily understood, the following is described in combination with the specific embodiments of the present application and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0040] The drawings are only used to show the principles, implementation modes, applications, characteristics and effects of the specific embodiments of the present application and other related contents, and cannot be considered as a limitation of the present application.

[0041] In the drawings of the specification:

[0042] Figure 1 Schematic diagram of molecular structure of regenerated and virgin polyester (PET) fibers at room temperature;

[0043] Figure 2 Differential scanning calorimetric diagram of virgin polyester (white) fiber reference sample;

[0044] Figure 3 Differential scanning calorimetric diagram of virgin polyester (black) fiber reference sample;

[0045] Figure 4 Differential scanning calorimetric diagram of recycled polyester (white) fiber reference sample;

[0046] Figure 5 Differential scanning calorimetric diagram of recycled polyester (black) fiber reference sample;

[0047] Figure 6 Differential scanning calorimetric diagram of polyester (white) fiber sample 1 to be identified;

[0048] Figure 7 Differential scanning calorimetry plot for polyester (white) fiber sample 2 to be identified;

[0049] Figure 8 Differential scanning calorimetry plot for polyester (white) fiber sample 3 to be identified;

[0050] Figure 9 Differential scanning calorimetry plot for polyester (black) fiber sample 4 to be identified;

[0051] Figure 10 Differential scanning calorimetry plot for polyester (purple) fiber sample 5 to be identified;

[0052] Figure 11 Differential scanning calorimetry plot for polyester (orange) fiber sample 6 to be identified;

[0053] Figure 12 Differential scanning calorimetry plot for polyester (purple) fiber sample 7 to be identified with polyurethane coating;

[0054] Figure 13 Differential scanning calorimetry plot for polyester (orange) fiber sample 8 to be identified with polyurethane coating. DETAILED DESCRIPTION

[0055] In order to make the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved of the present application more clear, the following will be described in detail in combination with the specific embodiments listed and with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0056] In this document, the term "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, and does not particularly limit the independence or association between other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, each technical feature mentioned in each embodiment can be combined in any way to form a corresponding implementable technical solution.

[0057] Unless otherwise defined, the meanings of the technical terms used herein are the same as those commonly understood by those skilled in the art to which the present application belongs; the use of related terms in this document is only for the purpose of describing specific embodiments, and is not intended to limit the present application.

[0058] In the description of the present application, the phrase "and / or" is a description of a logical relationship between objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases: A exists, B exists, and A and B exist at the same time. In addition, the character " / " herein generally represents that the associated objects before and after are a "or" logical relationship.

[0059] In the present application, the terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, primary and secondary or order relationship between the entities or operations.

[0060] In the present application, without more limitation, the "includes", "contains", "has" or other similar open expressions used in the sentence are intended to cover non-exclusive inclusion, and these expressions do not exclude the existence of other elements in the process, method or product including the described elements, so that the process, method or product including a series of elements can not only include those limited elements, but also include other elements not explicitly listed, or also include the elements inherent in such process, method or product.

[0061] As the same understanding as in the "Guidelines for Examination", in the present application, the expressions such as "greater than", "less than", "exceed" are understood as not including the number; the expressions such as "above", "below", "within" are understood as including the number. In addition, in the description of the embodiments of the present application, the meaning of "multiple" is more than two (including two), and similar expressions related to "multiple" are also understood in this way, for example, "multiple groups", "multiple times" and the like, unless otherwise explicitly limited.

[0062] In the description of the embodiments of the present application, the spatial-related expressions used, such as "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or the drawings, and are only for the convenience of describing the specific embodiments of the present application or for the reader to understand, and do not indicate or imply that the indicated device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0063] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. For those skilled in the art to which this application pertains, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0064] The differential scanning calorimeter used in the embodiments of this application is a PerkinElmer DSC8500.

[0065] The reference samples of virgin polyester fiber and recycled polyester fiber in the embodiments of this application came from the Shanghai Textile Industry Technical Supervision Institute, and the recycled polyester fiber suppliers certified by GRS included Shenzhen Fengze Textile Co., Ltd., Dongguan Juxiangxin Textile Co., Ltd., and Sakura Thread Factory.

[0066] Example 1: Differential scanning calorimetry curves and temperature-absorption peak characteristics of a virgin white polyester fiber reference sample.

[0067] A 0.5g sample of virgin white polyester fiber reference was cut into fiber samples with an average length of 0.1-1mm using a Hastelloy slicer. 1-5mg of the cut virgin white polyester fiber reference sample was placed in an aluminum crucible and then placed in the sample furnace of a PerkinElmer DSC8500 differential scanning calorimeter. Under nitrogen atmosphere, the temperature was increased from room temperature to 500℃ at a rate of 20℃ / min. The differential scanning calorimetry curve of the virgin white polyester fiber reference sample was recorded. Figure 2 The differential scanning calorimetry curve of the virgin white polyester fiber reference sample is shown.

[0068] from Figure 2 Analysis revealed that the virgin white polyester fiber reference sample exhibited two thermal absorption peaks at approximately 250℃ and 255℃. The thermal absorption peak at 250℃ corresponds to the oligomers within the virgin white polyester fiber reference sample molecule, while the thermal absorption peak at 255℃ corresponds to the macromolecular backbone of the virgin white polyester fiber reference sample; furthermore, the intensity of the thermal absorption peak at 255℃ is more than twice that at 250℃.

[0069] Example 2: Differential scanning calorimetry curves and temperature-absorption peak characteristics of virgin black polyester fiber reference samples.

[0070] The 0.5 g virgin black polyester fiber reference sample was cut into fiber samples with an average length of 0.1-1 mm using a Haggstrom slicer; 1-5 mg of the cut virgin black polyester fiber reference sample was placed in an aluminum crucible and put into a sample furnace of a DSC8500 differential scanning calorimeter of PerkinElmer, and the virgin black polyester fiber reference sample was raised from room temperature to 500°C at a rate of 20°C / min under a nitrogen atmosphere, and a differential scanning calorimetry curve of the virgin black polyester fiber reference sample was recorded, and a Figure 2 differential scanning calorimetry curve of the virgin black polyester fiber reference sample was obtained.

[0071] From the analysis of Figure 3 , it can be seen that the virgin black polyester fiber reference sample has two reaction heat absorption peaks at about 250°C and 254°C. The reaction heat absorption peak at a temperature of 250°C corresponds to the oligomers in the virgin black polyester fiber reference sample, and the reaction heat absorption peak at a temperature of 254°C corresponds to the macromolecular backbone of the virgin black polyester fiber reference sample; and the intensity of the reaction heat absorption peak at a temperature of 254°C is greater than one time the intensity of the reaction heat absorption peak at a temperature of 250°C.

[0072] The comparative relationship of the differential scanning calorimetry reaction heat absorption peaks of the virgin white polyester fiber reference sample and the virgin black polyester fiber reference sample obtained in Example 1 and Example 2 is shown in Table 1.

[0073] Table 1 Comparative relationship of differential scanning calorimetry reaction heat absorption peaks of virgin white polyester fiber reference sample and virgin black polyester fiber reference sample

[0074]

[0075] Example 3 Differential scanning calorimetry curve of the recycled white polyester fiber reference sample and analysis of its temperature-absorption peak characteristics

[0076] The 1 g recycled white polyester fiber reference sample was cut into fiber samples with an average length of 1 mm using a Haggstrom slicer, 2 mg of the cut recycled white polyester fiber reference sample was placed in an aluminum crucible and put into a sample furnace of a DSC8500 differential scanning calorimeter of PerkinElmer, and the recycled white polyester fiber reference sample was raised from room temperature to 500°C at a rate of 20°C / min under a nitrogen atmosphere, and a differential scanning calorimetry curve of the recycled white polyester fiber reference sample was recorded, and a Figure 4 differential scanning calorimetry curve of the recycled white polyester fiber reference sample was obtained.

[0077] From the analysis of Figure 4Analysis reveals that the recycled white polyester fiber reference sample in this embodiment exhibits two thermal absorption peaks at approximately 251°C and 257°C. The thermal absorption peak at 251°C corresponds to the oligomers within the molecules of the recycled white polyester fiber reference sample, while the thermal absorption peak at 257°C corresponds to the macromolecular backbone of the recycled white polyester fiber reference sample. The intensity of the thermal absorption peak at 251°C is greater than that at 257°C.

[0078] Example 4: Differential scanning calorimetry curves and temperature-absorption peak characteristics of a recycled black polyester fiber reference sample.

[0079] A 1g recycled black polyester fiber reference sample was cut into fiber samples with an average length of 1mm using a Hastelloy slicer. 2mg of the cut recycled black polyester fiber reference sample was placed in an aluminum crucible and then placed in the sample furnace of a PerkinElmer DSC8500 differential scanning calorimeter. Under nitrogen atmosphere, the temperature was increased from room temperature to 500℃ at a rate of 20℃ / min. The differential scanning calorimetry curve of the recycled black polyester fiber reference sample was recorded. Figure 5 The differential scanning calorimetry curve of the reference sample of recycled black polyester fiber is shown.

[0080] from Figure 5 Analysis revealed that the recycled black polyester fiber reference sample exhibited two thermal absorption peaks at approximately 249℃ and 256℃. The thermal absorption peak at 249℃ corresponds to the oligomer of the recycled black polyester fiber reference sample, while the thermal absorption peak at 256℃ corresponds to the macromolecular backbone of the recycled black polyester fiber reference sample. The intensity of the thermal absorption peak at 249℃ was greater than that at 256℃.

[0081] The comparison of the differential scanning calorimetry reaction thermal absorption peaks of the recycled white polyester fiber reference sample and the recycled black polyester fiber reference sample obtained in Examples 3 and 4 is shown in Table 2.

[0082] Table 2. Comparison of Differential Scanning Calorimetry Reactive Absorption Peaks between Recycled White Polyester Fiber Reference Samples and Recycled Black Polyester Fiber Reference Samples

[0083]

[0084] Example 5: Qualitative and semi-quantitative identification of white polyester fiber sample 1 to be identified using the technical solution of this invention, and the results thereof.

[0085] A 1g sample of white polyester fiber to be identified was cut into fiber samples with an average length of 1mm using a Hastelloy slicer. 2mg of the cut sample was placed in an aluminum crucible and then placed inside the sample furnace of a PerkinElmer DSC8500 differential scanning calorimeter. Under nitrogen atmosphere, the temperature was increased from room temperature to 500℃ at a rate of 20℃ / min. The differential scanning calorimetry curve of the white polyester fiber sample was recorded. Figure 6 The differential scanning calorimetry curve of polyester (white) fiber sample 1 to be identified is shown.

[0086] from Figure 6 Analysis revealed that sample 1, a white polyester fiber to be identified, exhibited three thermal absorption peaks at approximately 248℃, 250℃, and 252℃ (in cases where there are more than two thermal absorption peaks). Due to the influence of different oligomers, the thermal absorption peaks shifted to lower temperatures compared to virgin polyester fibers, and the intensities of the three thermal absorption peaks were comparable. Therefore, sample 1, a white polyester fiber to be identified, was determined to be recycled polyester fiber.

[0087] Semi-quantitative comparative analysis: The differential scanning calorimetry (DSC) curve of the fiber sample was compared with the DSC curve of the reference sample of recycled polyester fiber obtained by the method in Example 3. The fiber sample showed three reaction heat absorption peaks. The reaction heat absorption peak at low temperature (248℃) and high temperature (252℃) was shifted to the lower temperature than the reaction heat absorption peak at low temperature (251℃) and high temperature (257℃) in Example 3. Therefore, it can be determined that the fiber to be identified is recycled polyester fiber, and the degree of recycling is greater than that of the sample in Example 3.

[0088] Example 6: Qualitative and semi-quantitative identification of white polyester fiber sample 2 to be identified using the technical solution of the present invention and the results thereof.

[0089] A 1g sample of white polyester fiber to be identified was cut into fiber samples with an average length of 1mm using a Hastelloy slicer. 2mg of the cut sample was placed in an aluminum crucible and then placed inside the sample furnace of a PerkinElmer DSC8500 differential scanning calorimeter. Under nitrogen atmosphere, the temperature was increased from room temperature to 500℃ at a rate of 20℃ / min. The differential scanning calorimetry curve of the sample was recorded. Figure 7 The differential scanning calorimetry curve of sample 2 of polyester (white) fiber to be identified is shown.

[0090] from Figure 7From the analysis, the polyester (white) fiber sample 2 to be identified appears three reaction heat absorption peaks at temperatures of about 244℃, 249℃ and 254℃. The reaction heat absorption peaks at temperatures of 244℃ and 249℃ correspond to the oligomers in the polyester (white) fiber sample 2 to be identified, and the reaction heat absorption peak at a temperature of 254℃ corresponds to the macromolecular main chain of the polyester (white) fiber sample 2 to be identified. Due to the influence of different oligomers, the reaction heat absorption peaks at temperatures of 244℃ and 249℃ are offset to low temperatures compared with the virgin polyester fiber, and the intensity of the reaction heat absorption peaks at temperatures of 244℃ and 249℃ is much greater than that of the reaction heat absorption peak at a temperature of 254℃. Therefore, it is determined that the polyester (white) fiber sample 2 to be identified is a regenerated polyester fiber.

[0091] Semi-quantitative comparison analysis: The differential scanning calorimetric curve of the fiber sample is compared with the differential scanning calorimetric curve of the recycled polyester fiber reference sample obtained by the method in Example 3. The fiber sample appears three reaction heat absorption peaks, and the low-temperature reaction heat absorption peak (244℃) and the high-temperature reaction heat absorption peak (254℃) are both offset to low temperatures compared with the low-temperature reaction heat absorption peak (251℃) and the high-temperature reaction heat absorption peak (257℃) in Example 3. It can be judged that the fiber to be identified is a recycled polyester fiber, and the degree of polymerization of the recycled polyester fiber is greater than that of the sample in Example 3.

[0092] Further, the differential scanning calorimetric curve of the fiber sample is compared with the differential scanning calorimetric curve of the recycled polyester fiber sample obtained by the method in Example 5. The intensity of the low-temperature reaction heat absorption peak (244℃) of the fiber sample is greater than that of the high-temperature reaction heat absorption peak (254℃), while the intensity of the low-temperature reaction heat absorption peak (248℃) in Example 5 is less than that of the high-temperature reaction heat absorption peak (252℃). The low-temperature reaction heat absorption peak (244℃) of the fiber sample is shifted to a low temperature direction compared with the low-temperature reaction heat absorption peak (248℃) in Example 5, and the temperature difference range of the low-temperature reaction heat absorption peak (244℃) and the high-temperature reaction heat absorption peak (254℃) of the fiber sample is greater than that of the low-temperature reaction heat absorption peak (248℃) and the high-temperature reaction heat absorption peak (252℃) in Example 5. It can be judged that the degree of polymerization of the recycled polyester fiber to be identified is greater than that of the sample in Example 5.

[0093] Example 7 qualitatively and semi-quantitatively identifies the white polyester fiber sample 3 to be identified and the results thereof

[0094] A 1 g sample of the polyester (white) fiber to be identified 3 was cut into fibers with an average length of 1 mm using a Haggstrom slicer; 2 mg of the cut sample of the polyester (white) fiber to be identified 3 was placed in an aluminum crucible and put into a sample furnace of a DSC8500 differential scanning calorimeter of PerkinElmer, and then the sample was heated at a rate of 20 ℃ / min from room temperature to 500 ℃ under a nitrogen atmosphere, and a differential scanning calorimetry curve of the polyester (white) fiber to be identified 3 was recorded, and a differential scanning calorimetry curve of the polyester (white) fiber to be identified 3 was obtained as shown in FIG. 2. Figure 8 The differential scanning calorimetry curve of the polyester (white) fiber to be identified 3 is shown in FIG. 2.

[0095] From the analysis in FIG. 2, it can be seen that, due to the influence of different oligomers, the polyester (white) fiber to be identified 3 has a very wide reaction heat absorption peak at a temperature of 240-250 ℃. The reaction heat absorption peak is shifted to a lower temperature compared with the virgin polyester fiber. Therefore, it is determined that the polyester (white) fiber to be identified 3 is a regenerated polyester fiber. Figure 8 The differential scanning calorimetry curve of the fiber sample was compared with the differential scanning calorimetry curve of the recycled regenerated polyester fiber reference sample obtained by the method in Example 3. The fiber sample has a very wide reaction heat absorption peak, and the reaction heat absorption peaks at both ends (240 ℃ and 250 ℃) are shifted to a lower temperature than the reaction heat absorption peaks at low and high temperatures (251 ℃ and 257 ℃) in Example 3. Therefore, it can be judged that the fiber to be identified is a regenerated polyester fiber, and the degree of polymerization of the recycled regeneration is greater than that of the sample in Example 3.

[0096] Example 8: Qualitative and semi-quantitative identification of the polyester (black) fiber to be identified 4 by the technical solution of the present application and the results thereof

[0097] A 1 g sample of the polyester (black) fiber to be identified 4 was cut into fibers with a length of 1 mm using a Haggstrom slicer; 2 mg of the cut sample of the polyester (black) fiber to be identified 4 was placed in an aluminum crucible and put into a sample furnace of a DSC8500 differential scanning calorimeter of PerkinElmer, and then the sample was heated at a rate of 20 ℃ / min from room temperature to 500 ℃ under a nitrogen atmosphere, and a differential scanning calorimetry curve of the polyester (black) fiber to be identified 4 was recorded, and a differential scanning calorimetry curve of the polyester (black) fiber to be identified 4 was obtained as shown in FIG. 4.

[0098] The differential scanning calorimetry curve of the polyester (black) fiber to be identified 4 is shown in FIG. 4. Figure 9 From the analysis in FIG. 4, it can be seen that, due to the influence of different oligomers, the polyester (black) fiber to be identified 4 has a very wide reaction heat absorption peak at a temperature of 240-250 ℃. The reaction heat absorption peak is shifted to a lower temperature compared with the virgin polyester fiber. Therefore, it is determined that the polyester (black) fiber to be identified 4 is a regenerated polyester fiber.

[0099] Figure 9 ​Analysis revealed that, influenced by different oligomers, the polyester (black) fiber sample 4 exhibited multiple thermal absorption peaks at approximately 246℃, 248℃, 249℃, and 253℃. The thermal absorption peaks at lower temperatures corresponded to the oligomers, and their intensity was greater than that at 253℃. Therefore, the polyester (black) fiber sample 4 was determined to be recycled polyester fiber.

[0100] Semi-quantitative comparative analysis: The differential scanning calorimetry (DSC) curve of the fiber sample was compared with the DSC curve of the reference sample of recycled polyester fiber obtained by the method in Example 4. The fiber sample showed four reaction heat absorption peaks. The reaction heat absorption peak at low temperature (246℃) and high temperature (253℃) was shifted to the lower temperature than the reaction heat absorption peak at low temperature (249℃) and high temperature (256℃) in Example 4. Therefore, it can be determined that the fiber to be identified is recycled polyester fiber, and the degree of recycling is greater than that of the sample in Example 4.

[0101] Example 9: Qualitative and semi-quantitative identification of polyester (purple) fiber sample 5 to be identified using the technical solution of this invention, and the results thereof.

[0102] A 1g sample of the polyester (purple) fiber to be identified was cut into fiber samples with an average length of 1mm using a Hastelloy slicer. 2mg of the cut polyester (purple) fiber sample was placed in an aluminum crucible and then placed in the sample furnace of a PerkinElmer DSC8500 differential scanning calorimeter. Under nitrogen atmosphere, the temperature was increased from room temperature to 500℃ at a rate of 20℃ / min. The differential scanning calorimetry curve of the polyester (purple) fiber sample was recorded. Figure 10 The differential scanning calorimetry curve of sample 5 of the polyester (purple) fiber to be identified is shown.

[0103] from Figure 10 Analysis revealed that the polyester (purple) fiber sample 5 exhibited two thermal absorption peaks at approximately 242℃ and 252℃. The thermal absorption peak at 242℃ corresponds to the oligomer of the polyester (purple) fiber sample 5, while the peak at 252℃ corresponds to the main chain of the polyester macromolecule. Both thermal absorption peaks shifted to lower temperatures compared to virgin polyester fibers, and the temperature difference between the two peaks was greater than that of the virgin polyester fibers. Therefore, the polyester (purple) fiber sample 5 was determined to be recycled polyester fiber.

[0104] Semi-quantitative comparison analysis: the differential scanning calorimetry curve of the fiber sample is compared with the differential scanning calorimetry curves of the recycled polyester fiber reference samples obtained by the method in Example 3 and Example 4. If the two reaction heat absorption peaks (242°C and 252°C) of the fiber sample are both shifted to a lower temperature than the two reaction heat absorption peaks in Example 3 and Example 4, and the temperature difference range between the high and low temperatures is expanded to 10°C, it can be judged that the fiber to be identified is a recycled polyester fiber, and the degree of cyclic regeneration is greater than the degree of cyclic regeneration of the samples in Example 3 and Example 4.

[0105] Example 10 qualitative and semi-quantitative identification of the polyester (orange) fiber sample 6 to be identified by the technical solutions of the present application and the results thereof

[0106] The 1g polyester (orange) fiber sample 6 to be identified is cut into a fiber sample with an average length of 1mm using a Haas slicer; 2mg of the cut polyester (orange) fiber sample 6 to be identified is placed in an aluminum crucible and placed in the sample furnace of the DSC8500 differential scanning calorimeter of PerkinElmer, and the temperature is raised from room temperature to 500°C at a rate of 20°C / min under a nitrogen environment. The differential scanning calorimetry curve of the polyester (orange) fiber sample 6 to be identified is recorded, and the differential scanning calorimetry curve of the polyester (orange) fiber sample 6 to be identified is obtained as shown in FIG. 6. Figure 11

[0107] From the analysis in FIG. 6, it can be seen that the polyester (orange) fiber sample 6 to be identified has two reaction heat absorption peaks at temperatures of about 240°C and 250°C. The reaction heat absorption peak at a temperature of 240°C corresponds to the oligomer of the polyester (orange) fiber sample 6 to be identified, and the reaction heat absorption peak at a temperature of 250°C corresponds to the polyester macromolecular backbone of the polyester (orange) fiber sample 6 to be identified. Compared with the virgin polyester fiber, the reaction heat absorption peaks are both shifted to a lower temperature, and the temperature difference range of the two reaction heat absorption peaks is greater than the temperature difference range of the two reaction heat absorption peaks of the virgin polyester fiber. Therefore, it is determined that the polyester (orange) fiber sample 6 to be identified is a recycled polyester fiber. Figure 11 Semi-quantitative comparison analysis: the differential scanning calorimetry curve of the fiber sample is compared with the differential scanning calorimetry curves of the recycled polyester fiber reference samples obtained by the method in Example 3 and Example 4. If the two reaction heat absorption peaks (240°C and 250°C) of the fiber sample are both shifted to a lower temperature than the two reaction heat absorption peaks in Example 3 and Example 4, and the temperature difference range between the high and low temperatures is expanded to 10°C, it can be judged that the fiber to be identified is a recycled polyester fiber, and the degree of cyclic regeneration is greater than the degree of cyclic regeneration of the samples in Example 3 and Example 4.

[0108]

[0109] ​​Example 11 qualitative and semi-quantitative identification of the polyester (purple) fiber sample 7 with polyurethane coating by the technical solution of the present application and the results thereof

[0110] 1 g of the polyester (purple) fiber sample 7 with polyurethane coating to be identified was cut into 1 mm long fiber samples using a Haggstrom slicer; 2 mg of the cut polyester (purple) fiber sample 7 with polyurethane coating to be identified was placed in an aluminum crucible and put into the sample furnace of a PerkinElmer DSC8500 differential scanning calorimeter, and the differential scanning calorimetric curve of the polyester (purple) fiber sample 7 with polyurethane coating to be identified was recorded under nitrogen atmosphere at a rate of 20 ℃ / min from room temperature to 500 ℃, obtaining Figure 12 the differential scanning calorimetric curve of the polyester (purple) fiber sample 7 with polyurethane coating to be identified shown in FIG. 1.

[0111] From the analysis in Figure 12 , it can be known that the polyester (purple) fiber sample 7 with polyurethane coating to be identified has two reaction heat absorption peaks at temperatures of about 242 ℃ and 252 ℃. The reaction heat absorption peak at the temperature of 242 ℃ corresponds to the oligomer of the polyester (purple) fiber sample 7 with polyurethane coating to be identified, and the reaction heat absorption peak at the temperature of 252 ℃ corresponds to the polyester macromolecular backbone of the polyester (purple) fiber sample 7 with polyurethane coating to be identified; compared with the virgin polyester fiber, the reaction heat absorption peaks are all shifted to lower temperatures, and the temperature difference range of the two reaction heat absorption peaks is greater than that of the two reaction heat absorption peaks of the virgin polyester fiber. Therefore, it is determined that the polyester (purple) fiber sample 7 with polyurethane coating to be identified is a regenerated polyester fiber.

[0112] Semi-quantitative comparison analysis: the differential scanning calorimetric curve of the fiber sample was compared with the differential scanning calorimetric curves of the recycled polyester fiber reference samples obtained by the methods in Example 3 and Example 4; the two reaction heat absorption peaks (242 ℃ and 252 ℃) of the fiber sample are all shifted to lower temperatures compared with the two reaction heat absorption peaks in Example 3 and Example 4, and the temperature difference range at high and low temperatures is expanded to 10 ℃, so it can be judged that the fiber to be identified is a regenerated polyester fiber, and the degree of the recycling process is greater than that of the samples in Example 3 and Example 4.

[0113] Example 12 qualitative and semi-quantitative identification of the polyester (orange) fiber sample 8 with polyurethane coating by the technical solution of the present application and the results thereof

[0114] A 1g sample of polyurethane-coated polyester (orange) fiber to be identified was cut into fiber samples with an average length of 1mm using a Hastelloy slicer. 2mg of the cut polyurethane-coated polyester (orange) fiber sample was placed in an aluminum crucible and then placed in the sample furnace of a PerkinElmer DSC8500 differential scanning calorimeter. Under nitrogen atmosphere, the temperature was increased from room temperature to 500℃ at a rate of 20℃ / min. The differential scanning calorimetry curve of the polyurethane-coated polyester (orange) fiber sample was recorded. Figure 13 The differential scanning calorimetry curve of the polyester (orange) fiber sample 8 with polyurethane coating to be identified is shown.

[0115] from Figure 13 Analysis revealed that the polyurethane-coated polyester (orange) fiber sample 8 exhibited two thermal absorption peaks at approximately 241℃ and 252℃. The thermal absorption peak at 241℃ corresponds to the oligomer of the polyurethane-coated polyester (orange) fiber sample 8, while the peak at 252℃ corresponds to the main chain of the polyester macromolecule. Both thermal absorption peaks shifted to lower temperatures compared to virgin polyester fibers, and the temperature difference between the two peaks was greater than that of the virgin polyester fibers. Therefore, the polyurethane-coated polyester (orange) fiber sample 8 was determined to be recycled polyester fiber.

[0116] Semi-quantitative comparative analysis: The differential scanning calorimetry (DSC) curve of this fiber sample was compared with the DSC curve of the reference sample of recycled polyester fiber obtained by the methods in Examples 3 and 4. The two reaction heat absorption peaks (241℃ and 252℃) of this fiber sample were shifted to lower temperatures than the two reaction heat absorption peaks in Examples 3 and 4, and the temperature difference range between the high and low temperatures was expanded to 11℃. Therefore, it can be determined that the fiber to be identified is recycled polyester fiber, and the degree of recycling is greater than that of the samples in Examples 3 and 4.

[0117] The technical solutions represented by the above embodiments of the present application do not use any solvent such as an acid or a base solution, and no solution material such as waste water is discharged during the identification process, thus having the environmental friendly feature. Secondly, the main time for the qualitative identification operation is the collection time of the PerkinElmer DSC8500 differential scanning calorimeter, in addition to the cutting of the polyester fiber sample to be identified. For example, at a temperature increasing rate of 20℃ / min, the time required for one sampling is less than 30 min from room temperature 25℃ to 500℃. In the fiber component analysis, 0.1-1g sample is a large amount, and the sample amount used in the common fiber differential scanning calorimetry experiment or spectrum experiment is 1-10mg. In addition, the large amount here also refers to the number of fibers, usually several hundred fibers, which also reflects the integrity and representativeness of the sample, avoiding the defect that a single sample is not representative. Since a large amount of fiber samples are used for the experiment, the experimental results are representative, and thus it is not necessary to repeat the differential scanning calorimetry test. In summary, the technical solutions of the present application have the advantages of high efficiency, accuracy and environmental protection for the qualitative problem of whether the polyester fiber to be identified is virgin or recycled, and for the semi-quantitative distinction of how many times the recycled polyester fiber is recycled. In addition, the implementation of the technical solutions of the present application is not affected by whether the polyester fiber to be identified has dyeing pigments and coating materials. The inventor has verified through repeated, large and multiple experiments (including blind selection experiments) of the virgin polyester fiber and recycled polyester fiber samples provided by the fiber manufacturer or the textile enterprise, and the identification results are consistent with the actual types of the products, the identification accuracy is consistent, and the accuracy of the identification method is as high as 100%.

[0118] Finally, it should be noted that although the above embodiments have been described in the specification and drawings of the present application, the patent protection scope of the present application should not be limited. Any technical solution obtained by replacing or modifying the equivalent structure or equivalent flow based on the essential concept of the present application, using the content described in the specification and drawings of the present application, and directly or indirectly implementing the technical solutions of the above embodiments in other related technical fields, etc., are all included in the patent protection scope of the present application.

Claims

1. A rapid detection method of recycled polyester fibers, characterized by, The method comprises the following steps: Preparation of fiber sample: cutting the polyester fiber to be identified into fiber samples; Differential scanning calorimetry curve collection: placing a proper amount of the fiber sample into an aluminum crucible and covering it, and then placing it in a differential scanning calorimeter to perform differential scanning calorimetry detection, and recording the differential scanning calorimetry curve of the fiber sample; Qualitative and semi-quantitative analysis: comparing the differential scanning calorimetry curve with the differential scanning calorimetry curve of the reference sample, analyzing the reaction heat absorption peaks corresponding to the differential scanning calorimetry curve, and determining the qualitative result of the polyester fiber to be identified as virgin polyester fiber or recycled polyester fiber according to the peak shape, relative intensity and temperature difference comparison analysis results of the reaction heat absorption peaks of the fiber sample and the reference sample, and semi-quantitatively distinguishing the recycling regeneration degree of the recycled polyester fiber, wherein the reference sample comprises virgin polyester fiber reference sample and recycled polyester fiber reference sample, the virgin polyester fiber reference sample comprises black virgin polyester fiber reference sample and white virgin polyester fiber reference sample, and the recycled polyester fiber reference sample comprises white recycled polyester fiber reference sample and black recycled polyester fiber reference sample; In the qualitative and semi-quantitative analysis step, the heating rate is 10-30℃ / min, If the fiber sample to be identified has two reaction heat absorption peaks, and both of the two reaction heat absorption peaks are shifted to the low temperature direction compared with the high temperature and low temperature reaction heat absorption peaks of the virgin polyester fiber reference sample, it is determined that the fiber sample to be identified is a recycled polyester fiber; If the fiber sample to be identified has one very wide reaction heat absorption peak, and the reaction heat absorption peak is shifted to the low temperature direction compared with the high temperature and low temperature reaction heat absorption peaks of the virgin polyester fiber reference sample, it is determined that the fiber sample to be identified is a recycled polyester fiber; If the fiber sample to be identified has two reaction heat absorption peaks, the intensity of the reaction heat absorption peak corresponding to the high temperature is equivalent to or less than the intensity of the reaction heat absorption peak corresponding to the low temperature, and both of the two reaction heat absorption peaks are shifted to the low temperature direction compared with the reaction heat absorption peaks of the virgin polyester fiber reference sample, it is determined that the fiber sample to be identified is a recycled polyester fiber; If the fiber sample to be identified has two reaction heat absorption peaks, the reaction heat absorption peak at low temperature is shifted to the low temperature direction compared with the reaction heat absorption peak at low temperature of the virgin polyester fiber reference sample, and the temperature difference range of the two reaction heat absorption peaks is greater than the temperature difference range of the two reaction heat absorption peaks of the virgin polyester fiber, it is determined that the fiber sample to be identified is a recycled polyester fiber; If the fiber sample to be identified has more than two reaction heat absorption peaks, and the reaction heat absorption peaks are shifted to the low temperature direction compared with the reaction heat absorption peaks of the virgin polyester fiber reference sample, and the intensity of the reaction heat absorption peak corresponding to the high temperature is less than the intensity of the reaction heat absorption peak corresponding to the low temperature, it is determined that the fiber sample to be identified is a recycled polyester fiber.

2. The rapid detection method according to claim 1, characterized in that, The average length of the fiber sample is 0.1-1mm.

3. The rapid detection method according to claim 1, characterized in that, In the differential scanning calorimetry curve collection step of the fiber sample, the amount of the fiber sample used is 1-5mg.

4. The rapid detection method of claim 1, wherein, The differential scanning calorimetry curve collecting step further comprises a step of pre-setting an inert gas atmosphere in the differential scanning calorimeter.

5. The rapid detection method of claim 1, wherein, The differential scanning calorimetry curve collecting step further comprises a step of pre-setting an inert gas atmosphere in the differential scanning calorimeter.

6. Use of the rapid test method according to any one of claims 1 to 5 for the qualitative semi-quantitative identification of polyester fibres as virgin polyester fibres or recycled polyester fibres, wherein The semi-quantitative identification is a determination of the recycling regeneration degree of the regenerated polyester fiber.

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