A qualitative identification method for cuprammonia fiber and lyocell fiber and its application

Abstract

The present invention discloses a qualitative identification method and application of cuprammonium fiber and lyocell fiber, so as to fill the technical gap that the prior art cannot effectively identify cuprammonium fiber and lyocell fiber. The method comprises the following steps: sample preparation: cutting the fiber to be identified into fiber samples; mixing the fiber sample with the window material evenly, and placing it on a tablet press to press it into a transparent thin sheet; placing the transparent thin sheet in a temperature-increasing infrared spectrum window; heating the infrared spectrometer to 500°C, and recording the infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at preset interval temperature points; comparing the infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at the preset interval temperature points with the infrared spectra of the molecular thermal motion and thermal decomposition of the reference sample, with the wave number of 1650cm ‑1 Position and 1600cm ‑1 The absorption peak characteristics at different temperatures at different locations are compared and analyzed to determine whether the fiber to be identified is cuprammonium fiber or lyocell fiber.

Description

Technical Field

[0001] The invention relates to the technical field of fiber identification, and in particular to a qualitative identification method and application of cuprammonia fiber and lyocell fiber. Background Art

[0002] Regenerated cellulose fiber (cellulose fiber) uses natural cellulose (cotton, linen, bamboo, trees, shrubs, etc.) as raw materials. In the process of preparing regenerated cellulose fiber, the chemical structure of natural cellulose remains unchanged, and only the physical structure of natural cellulose is changed, so it has better performance and is highly welcomed by the market. In recent years, under the guidance of the concept of green and environmentally friendly life, the demand for regenerated cellulose fiber has further grown rapidly.

[0003] As regenerated cellulose fibers in dissolving pulp, cuprammonium fiber and lyocell fiber are widely used in textiles at home and abroad. Cuprammonium fiber is made by dissolving natural cellulose raw materials such as cotton linters in a concentrated ammonia solution of copper hydroxide or alkaline copper salt to prepare a spinning solution. In the coagulation bath, cuprammonium cellulose molecular chemicals are decomposed to regenerate cellulose. The resulting hydrated cellulose is processed to obtain cuprammonium fiber. The cross-section of cuprammonium fiber is round and has no skin-core structure. The fiber can withstand high stretching. The obtained monofilament is thinner, so the fabric feels soft, has a soft luster, and has a silky feel. Cuprammonium fiber has four major functions: breathable, refreshing, antistatic, and good drape. It is often used to make high-end silk or knitted fabrics, which conforms to the trend of environmentally friendly clothing and has an irreplaceable position. Lyocell fiber, also known as "Tencel", is a mixture of wood pulp mainly from coniferous trees, water and solvent NMMO (4-methylmorpholine-N-oxide), heated until completely dissolved. No derivatives or chemical reactions will be produced during the dissolution process. After impurities are removed, it can be directly spun. Its molecular structure is a simple carbohydrate. Lyocell fiber can be completely decomposed in the soil and does not pollute the environment. In addition, the amine oxide solvent used in production is completely harmless to the human body, can be almost completely recycled, and can be used repeatedly. The cellulose molecules contained in the raw pulp in production do not undergo chemical changes, there are no by-products, and no waste is discharged outside the factory. It is an environmentally friendly or green fiber. The fiber fabric has good hygroscopicity, comfort, drape, stiffness and dyeability, and Lyocell fiber can be blended with cotton, wool, linen, nitrile, polyester, etc. It can be ring-spun, air-spun, core-spun, and spun into various cotton-type and wool-type yarns, core-spun yarns, etc. Therefore, the fiber can be used not only in the production of underwear fabrics, but also in the production of outerwear fabrics. In short, the manufacturing process of cupro-ammonia fiber and lyocell fiber is energy-saving, environmentally friendly, and sustainable, and is known as the green fiber of the 21st century. As recycled fibers, they are green, environmentally friendly and recyclable, and are favored by manufacturers and consumers.

[0004] The existing textile industry standards FZ / T 01057-2007 and FZ / T 01057-2012 basically use combustion method, microscopy method, dissolution method, melting point method, density gradient method, etc. to determine and distinguish the types of fibers. These methods will bring different problems when qualitatively identifying fibers. For example, the dissolution method requires the use of acid-base solution or other solvents to dissolve the fibers, which will inevitably produce environmentally unfriendly test wastewater after identification; the microscopy method requires the use of a microscope to determine the changes in fiber morphology, which requires high professional quality and experience of identification personnel; other methods also have the problem of requiring a large number of repeated tests to obtain average results to determine the fiber type, and the identification results are inaccurate.

[0005] Cuprammonia fiber and lyocell fiber are basically the same in appearance: the longitudinal section surface is smooth and shiny, and the cross section is round; both fibers are regenerated cellulose fibers, with very similar chemical properties, and slight differences in molecular crystallinity and degree of polymerization. Conventional microscopic observation, combustion and dissolution methods cannot effectively identify them. Therefore, it is urgent to study an efficient, environmentally friendly and accurate qualitative identification method for cuprammonia fiber and lyocell fiber to meet the needs of market players and protect the rights and interests of consumers. Summary of the invention

[0006] To this end, it is necessary to provide a qualitative identification method and application of cuprammonium fiber and lyocell fiber, so as to provide a qualitative detection method of cuprammonium fiber and lyocell fiber that does not use any solution and solvent and is efficient and environmentally friendly for the field of fiber identification technology, filling the technical gap in the current conventional fiber identification methods that conventional microscope observation method, combustion method and dissolution method cannot effectively identify cuprammonium fiber and lyocell fiber.

[0007] To achieve the above object, in one aspect of the present invention, the inventor provides a method for qualitatively identifying cuprammonium fiber and lyocell fiber, comprising the following steps:

[0008] Sample preparation: Cut the fiber to be identified into fiber samples;

[0009] Preparation of transparent sheet: the fiber sample and the window sheet material are mixed evenly, and then placed on a sheet press to be pressed into a transparent sheet;

[0010] The transparent sheet is placed in a temperature-elevable device and in front of the infrared spectrometer window;

[0011] The temperature of the heating device is raised to 500° C., and infrared spectra of thermal motion and thermal decomposition of the fiber sample molecules at preset interval temperature points are recorded;

[0012] The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at the preset interval temperature points are compared with the infrared spectra of the molecular thermal motion and thermal decomposition of the reference sample. -1 Position and 1600cm -1 The absorption peak characteristics at different temperatures at different locations are compared and analyzed to determine whether the fiber to be identified is cuprammonium fiber or lyocell fiber.

[0013] The copper ammonia fiber and lyocell fiber to be identified by the present invention are very similar in appearance, touch and chemical properties, and they cannot be accurately and efficiently distinguished by conventional fiber identification methods. However, the inventors found that there are slight differences in crystallinity and polymerization degree between copper ammonia fiber and lyocell fiber, and the slight differences in crystallinity and polymerization degree will affect the molecular motion of the fiber, and the internal motion of the molecule determines the properties of the molecular spectrum. For copper ammonia fiber and lyocell fiber at room temperature, the fiber molecules are below the glass transition temperature, and the molecular motion is subject to certain constraints. Raising the temperature of their samples to be tested can increase the motion activity of the molecules. For example, when the temperature is raised to above the glass transition temperature of the fiber, the molecular chain can move freely. Therefore, the infrared of the temperature rise can more fully collect the spectral information corresponding to the molecular thermal motion. Moreover, at room temperature, since the molecular structure and element composition of copper ammonia fiber and lyocell fiber are exactly the same, they cannot be distinguished regardless of whether the mid-infrared or far-infrared at room temperature is used. Therefore, it is not feasible to distinguish the two fibers according to the molecular motion spectrum at room temperature. Based on the principles of thermal motion and thermal stability of fiber molecules, the inventors collected infrared spectra of fiber samples at different temperatures without using any solutions or solvents to reflect the changes in molecular microscopic thermal motion and pyrolysis properties, and displayed them in the form of absorption spectra to achieve the purpose of qualitative identification.

[0014] Infrared light is a type of electromagnetic wave. Electromagnetic waves are arranged in a certain order of wavelength or wave number, and are mainly divided into radio waves, microwaves, infrared light (rays), visible light, ultraviolet light (rays), X-rays and gamma rays. Infrared light (rays) belongs to molecular spectrum, and there are two types: infrared emission spectrum and infrared absorption spectrum. The commonly used one is infrared absorption spectrum. The absorption of infrared light by molecules is recorded by instruments to obtain infrared spectrum. Infrared absorption spectrum is produced by the constant vibration and rotation of molecules. Molecular vibration refers to the relative movement of atoms in molecules near the equilibrium position. Polyatomic molecules can form a variety of vibration patterns. When atoms in a molecule perform simple harmonic vibrations near the equilibrium position at the same frequency and the same phase, this vibration mode is called simple normal vibration (such as stretching vibration and angular vibration). The energy of molecular vibration corresponds exactly to the energy of infrared light quanta. Therefore, when the vibration state of the molecule changes, infrared spectrum can be emitted, and infrared absorption spectrum can also be produced due to the vibration of the molecule caused by infrared radiation. The energy of molecular vibration and rotation is not continuous but quantized. However, since the vibration transition of molecules is often accompanied by rotation transition, the vibration spectrum is band-shaped. Classification of infrared absorption spectrum: According to the infrared wave number test range, the infrared spectrum can be divided into three types: near infrared, mid infrared and far infrared. Near infrared light refers to the frequency between 12500-4000cm -1 The near-infrared spectrum is generated by electromagnetic waves in the range of (wavelength 0.8-2.5μm), mainly due to the non-resonance of molecular vibration, which makes it possible for molecular vibration to transition from the ground state to the high energy level. In the near-infrared spectrum, what is measured is mainly the double frequency and combined frequency absorption of the vibration of hydrogen-containing groups XH (X=C, N, O, S, etc.). The main technical features of near-infrared spectroscopy analysis are as follows: (1) fast analysis speed; (2) high analysis efficiency; (3) low analysis cost; (4) good test reproducibility; (5) easy to realize online analysis; (6) typical non-destructive analysis. Modern near-infrared spectroscopy also has its inherent weaknesses: first, the test sensitivity is relatively low, which is mainly because the near-infrared spectrum has a low probability of non-resonant absorption transition of molecular vibrations. Generally, the spectral band intensity of near-infrared harmonics and combined frequencies is 10 to 10,000 of its fundamental frequency absorption. As far as the analysis of components is concerned, its content should generally be greater than 0.1%; second, it is an indirect analysis technology, and the model on which the method relies must first use standard reference methods or reference methods to determine the composition or property data of samples within a certain range. Therefore, the establishment of the model requires certain chemometric knowledge, costs and time.

[0015] Frequency is 4000-400cm -1The mid-infrared wavelength region (wavelength of 2.5-25μm) is the most commonly used region. The main technical features of mid-infrared spectroscopy analysis are as follows: Mid-infrared spectroscopy is mainly used for qualitative or quantitative analysis of organic compounds. However, conventional mid-infrared spectroscopy is not suitable for the determination of trace components because the sensitivity and signal intensity of testing trace components are relatively low. This is mainly due to the low probability of non-resonant absorption transitions of infrared spectroscopy as molecular vibrations; if there is no change in the dipole moment of the vibration of the group, it is infrared inactive and cannot provide information about the existence of the group; it is not suitable for analyzing aqueous samples because the hydroxyl peak in water interferes with the determination; the confirmation of the overall structure of the compound requires a standard spectrum or a known pure substance, otherwise the compound cannot be confirmed by a simple infrared spectrum.

[0016] The frequency of the far infrared spectrum is between 400-10cm -1 (wavelength is 25-100μm). The absorption bands in this region are mainly caused by pure rotational transitions in gas molecules, vibration-rotational transitions, stretching vibrations of heavy atoms in liquids and solids, certain angular vibrations, skeleton vibrations, and lattice vibrations in crystals. Since low-frequency skeleton vibrations can sensitively reflect changes in the structure of substances, it is particularly convenient for isomer research. In addition, far-infrared spectroscopy is also effective for quantitative analysis of organometallic compounds (including complexes), hydrogen bonds, and adsorption phenomena. In environmental analysis tests, the energy of the light source in the far-infrared spectral region is weak, unless it is used for phase identification; phase content analysis in samples; element content analysis in crystals; gem identification; polymorph variant research; isomorphic substitution research; crystal order research; gene existence form judgment; study of the molecular structure, molecular arrangement and functional group orientation of the material surface.

[0017] The conventional operation of infrared spectrometer is carried out at room temperature and includes the following steps:

[0018] 1. Turn on the power switch of the infrared spectrometer.

[0019] 2. Click on the computer screen to open the OMINIC workstation software.

[0020] 3. Click Settings to switch the screen to the settings interface and then initialize the instrument.

[0021] 4. Prepare potassium bromide blank tablets, sample tablets, or directly prepare potassium bromide tablets for samples.

[0022] 5. Place the pressed potassium bromide blank sheet (a blank potassium bromide sheet without sample) on the sample rack in the sample compartment of the spectrometer.

[0023] 6. Click the background button under the measurement button, enter the spectrum name, and confirm the collection of the reference background spectrum.

[0024] 7. After the background spectrum is collected, place the sample to be tested into the spectrometer and close the lid.

[0025] 8. The software can perform various processing on the spectrum as required, such as marking peaks, selecting Print from the File menu, and printing the spectrum as a report in different forms.

[0026] 9. Exit the system.

[0027] Different from the prior art, the technical solution of the present invention adopts mid-infrared heating technology, without the need for complex analysis methods such as modeling, and uses the infrared absorption spectrum of the fiber sample to be identified to show the changes in molecular microscopic thermal motion and pyrolysis performance, and then compares it with the absorption peak characteristics of the reference sample of cuprammonia fiber and the reference sample of lyocell fiber at a specific wavelength position and a specific temperature (such as 150°C or 300°C), and determines and distinguishes the fiber sample to be identified based on the comparison results, and the discrimination result is simpler and more intuitive. This is essentially different from the methods such as far-infrared room temperature identification of cotton fibers and other mixed fibers that may be used in the prior art. The technical solution of the present invention does not use any additional solvents, nor does it require other pretreatment of the fiber to be identified. It only takes about 30 minutes from obtaining the fiber to be identified to obtaining the identification result. The method is very efficient, environmentally friendly and accurate, and is suitable for widespread promotion in market entities and testing institutions that produce and sell cuprammonia fibers and lyocell fibers and their textiles.

[0028] In the qualitative identification method of cuprammonium fiber and lyocell fiber in some embodiments, the fiber to be identified is cuprammonium fiber or lyocell fiber. Since the technical solution of the present invention is to efficiently, environmentally friendly and accurately determine whether the fiber is cuprammonium fiber or lyocell fiber, that is, the identification object of the qualitative identification method of the present invention is cuprammonium fiber and lyocell fiber, two kinds of regenerated cellulose fibers. Their appearance is almost completely the same, and it is impossible to directly distinguish them by naked eye observation and touch alone. In addition, the chemical properties of cuprammonium fiber and lyocell fiber are very similar, and there are only slight differences in molecular crystallinity, degree of polymerization, etc. Therefore, it is preferred to select the fiber to be identified as one of cuprammonium fiber or lyocell fiber, rather than other non-regenerated cellulose fibers or other regenerated cellulose fibers that are completely different from cuprammonium fiber and lyocell fiber.

[0029] In the qualitative identification method of cuprammonium fiber and lyocell fiber in some embodiments, the heating rate of the infrared spectrometer when the temperature is raised to 500°C is 10-30°C / min. Such a setting is related to the characteristics of cuprammonium fiber and lyocell fiber to be identified, which change with temperature. If the heating rate is less than 10°C / min, the identification time will be prolonged due to the slow heating, and heat accumulation will occur, making the actual temperature of the sample higher than the temperature displayed on the temperature control device; if the heating rate is greater than 30°C / min, the temperature response cannot keep up, making the actual temperature of the sample lower than the temperature displayed on the infrared spectrometer temperature control device, affecting the identification result.

[0030] In the qualitative identification method of cuprammonia fiber and lyocell fiber in some embodiments, the preset interval temperature point is 10°C-100°C. The preset interval temperature point is related to the density of the infrared spectrum of the thermal motion and thermal decomposition of the fiber sample molecules. The smaller the value of the preset interval temperature point, the denser the infrared spectrum of the thermal motion and thermal decomposition of the fiber sample molecules; otherwise, the more dispersed. Too frequent acquisition frequency will prolong the identification time; too dispersed acquisition frequency may miss key change information, affecting identification.

[0031] In the qualitative identification method of cuprammonium fiber and lyocell fiber in some embodiments, the window material is potassium bromide. Potassium bromide crystals are in the mid-infrared spectrum test band (4000-600cm -1 ) is one of the most transparent (almost no absorption peak) window materials, the cheapest and most easily available, not seriously deliquescing, easy to use in actual measurements for a long time, and has mechanical strength that is easy to apply and suitable for processing into practical windows. In addition, cesium iodide (CsI) is also one of the most ideal window materials, but cesium iodide is slightly more expensive and slightly more deliquescent than potassium bromide. The present application prefers potassium bromide as the window material for identifying cuprammonium fiber and lyocell fiber based on the above considerations.

[0032] In the qualitative identification method of cuprammonia fiber and lyocell fiber in some embodiments, during the transparent sheet preparation step, 0.1-1 mg of the fiber sample is mixed with 20-40 mg of the window material. Too little sample will weaken the infrared spectrum signal, or even cause spectrum peak loss; too much sample will saturate the infrared signal, making analysis and identification impossible. Too little window material will cause incomplete sample preparation; too much window material will cause the pressed sheet to be too thick, affecting the infrared spectrum signal.

[0033] In the qualitative identification method of cuprammonium fiber and lyocell fiber in some embodiments, the pressure when the fiber is placed on a tablet press and pressed into a transparent sheet is 8-10 MPa. If the pressure is too low, the sheet will be thick and opaque, seriously affecting the infrared signal; if the pressure is too high, the sheet will break and it will be impossible to carry out the identification experiment.

[0034] In the qualitative identification method of cuprammonia fiber and lyocell fiber in some embodiments, the length of the fiber sample is 0.01-0.1 mm. Fiber samples with too short length are difficult to handle when mixed with potassium bromide for tableting; fiber samples with too long length will reduce the light transmittance of the sample and weaken the infrared signal.

[0035] In the qualitative identification method of cuprammonia fiber and lyocell fiber in some embodiments, the reference sample includes a cuprammonia fiber reference sample and a lyocell fiber reference sample, and the infrared spectrum of the molecular thermal motion and thermal decomposition of the fiber sample at the preset interval temperature point is compared and analyzed with the infrared spectrum of the molecular thermal motion and thermal decomposition of the reference sample. The cuprammonia fiber reference sample has a wavelength of 1650 cm -1 The absorption peak at the position is significantly weakened at 150℃, with a wave number of 1600cm -1 The absorption peak at the position begins to appear at 150°C; the wave number of the lyocell fiber reference sample is 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 300°C, with a wave number of 1600 cm -1 The absorption peaks at the left and right positions begin to appear at 300°C; the identification results of the fiber to be identified are obtained based on the comparison and analysis results. Wave number 1650cm -1 The left and right are the absorption peaks related to crystallinity in cuproammonia fiber and lyocell fiber. The crystallinity of lyocell fiber is higher than that of cuproammonia fiber, so the wave number of lyocell fiber at 300℃ is 1650cm -1 The absorption peak around 1650cm-1 is significantly weakened, while the wave number of cuprammonia fiber is 1650cm-1 -1 The absorption peak at the position of 1600cm -1 The absorption peak at the position is related to the molecular structure change caused by the thermal decomposition of cuprammonium fiber and lyocell fiber. Since the crystallinity of cuprammonium fiber is lower than that of lyocell fiber, the wave number is at 1600cm -1 The absorption peak of the fiber appears at 150℃, while the absorption peak of Lyocell fiber appears at 1600cm at 300℃. -1 For the present invention, not only the use of infrared absorption spectrum with heating in the mid-infrared band is a breakthrough in traditional identification means, but also how to analyze the identification results and draw identification conclusions is also a major contribution of the present invention.

[0036] To achieve the above-mentioned purpose of the present application, in another aspect of the present invention, the inventor provides the application of the qualitative identification method of cupro ammonium fiber and lyocell fiber described in the first aspect in identifying and distinguishing cupro ammonium fiber and lyocell fiber.

[0037] Different from the existing technology, the above technical scheme can efficiently and accurately determine whether the fiber to be identified is cuprammonium fiber or lyocell fiber when it is known that the fiber to be identified is either cuprammonium fiber or lyocell fiber, without adding other organic solvents or long-term instrument operation waiting for the results. It is more environmentally friendly, efficient and accurate, and provides an innovative fiber identification technical scheme, filling the technical gap in non-solvent identification of cuprammonium fiber and lyocell fiber, is suitable for large-scale industrial production practice, is conducive to promotion and application in the textile industry, and can promote the development of inspection and testing technology.

[0038] The above-mentioned records related to the invention content are only an overview of the technical solution of the present application. In order to enable ordinary technicians in the field to more clearly understand the technical solution of the present application, and then implement it according to the text of the specification and the contents recorded in the drawings, and to make the above-mentioned purpose and other purposes, features and advantages of the present application easier to understand, the following is an explanation in combination with the specific implementation mode and drawings of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings are only used to illustrate the principles, implementation methods, applications, characteristics and effects of the specific embodiments of the present application and other related contents, and shall not be considered as limitations of the present application.

[0040] In the drawings of the specification:

[0041] Figure 1 It is a schematic diagram of the molecular structure of cuprammonium fiber and lyocell fiber at room temperature;

[0042] Figure 2 This is the infrared spectrum of the thermal motion and thermal decomposition (25-500℃) of Lyocell fiber molecules;

[0043] Figure 3 This is the infrared spectrum of the thermal motion and thermal decomposition (25-500℃) of cuprammonia fiber molecules. DETAILED DESCRIPTION

[0044] In order to explain in detail the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0045] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may 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, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0046] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0047] In the description of this application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in an "or" logical relationship.

[0048] In the present application, terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship of quantity, priority or sequence between these entities or operations.

[0049] Without further limitations, in this application, the words "include", "comprises", "has" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0050] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than", "less than", "exceed" and the like are understood to exclude the number itself; expressions such as "above", "below", "within" and the like are understood to include the number itself. In addition, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups", "multiple times", etc., unless otherwise clearly and specifically limited.

[0051] In the description of the embodiments of the present application, space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating the reader's understanding, and do not indicate or imply that the referred 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.

[0052] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms such as "install", "connect", "connect", "fix", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For technicians in the technical field to which the present application belongs, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0053] The infrared spectrometer used in the examples of this application is a Nicolet 380 Fourier transform infrared spectrometer from Thermo Scientific; the spectral resolution is set to 4 cm -1 ,The number of scans is set to 32 times.

[0054] The temperature control instrument used in the embodiments of the present application is the Beijing UPSCO YPS-AT700 intelligent PID temperature controller.

[0055] The tablet press used in the examples of the present application is a YP-2 tablet press produced by Shanghai Shanyue Scientific Instrument Co., Ltd.

[0056] The potassium bromide used in the examples of the present application is potassium bromide crystal commonly used in infrared spectroscopy in the technical field, spectrally pure, dried in a drying oven for 24 hours before use, and operated under an infrared lamp during use.

[0057] The infrared lamp used in the embodiments of the present application is the Shanghai Minghua Yaming HW-250W infrared lamp.

[0058] Example 1

[0059] like Figure 1As shown in the figure, the molecular structures of cuprammonium fiber and lyocell fiber are the same at room temperature and can be represented by the same molecular structure diagram. However, after heating them separately and observing them in the mid-infrared band, different spectral information can be obtained. Figure 2 The mid-infrared absorption spectrum of the lyocell fiber reference sample at 50° C. heating intervals is shown. This embodiment provides a method for obtaining a mid-infrared spectrum of the molecular thermal motion and thermal decomposition of the lyocell fiber reference sample.

[0060] Specifically, 0.5 g of a known reference lyocell fiber is cut into a fiber sample with a length of 0.01 mm using a Hasse slicer; 0.1 mg of the lyocell fiber sample is mixed with 20 mg of potassium bromide powder and placed on a tablet press, and the tablet press presses the lyocell fiber sample and the potassium bromide powder uniformly mixed product into a transparent sheet at a pressure of 8 MPa, and places it in a ceramic heating ring and at the window of a Nicolet 380 Fourier transform infrared spectrometer, and a temperature control instrument is set to heat from room temperature 25°C to 500°C at a rate of 20°C / min, and the infrared spectra of thermal motion and thermal decomposition of the lyocell fiber molecules at each temperature point of 50°C are recorded to obtain Figure 2 The lyocell fiber reference sample spectrum shown is the basis for the technical solution of this application.

[0061] from Figure 2 The analysis shows that the lyocell fiber reference sample has a wave number of 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 300°C; -1 The absorption peaks at the left and right positions begin to appear at 300°C.

[0062] Example 2

[0063] See also Figure 3 The mid-infrared absorption spectrum of the cuprammonia fiber reference sample at 50° C. heating intervals is shown. This embodiment provides a method for obtaining a mid-infrared spectrum of the thermal motion and thermal decomposition of the cuprammonia fiber reference sample molecules.

[0064] Specifically, 0.5 g of a known reference cuprammonium fiber was cut into a fiber sample with a length of 0.01 mm using a Hasse slicer; 0.1 mg of the cuprammonium fiber sample was mixed with 20 mg of potassium bromide powder and placed on a tablet press, which was pressed into a transparent sheet at a pressure of 9 MPa and placed in a ceramic heating ring and placed at the window of a Nicolet 380 Fourier transform infrared spectrometer. The temperature control instrument was set to heat the sample from room temperature 25°C to 500°C at a rate of 20°C / min, and the infrared spectra of thermal motion and thermal decomposition of the cuprammonium fiber molecules at each temperature point of 50°C were recorded to obtain Figure 3 The copper ammonia fiber reference sample spectrum on which the technical solution of this application is based is shown.

[0065] from Figure 3 The analysis shows that the reference sample of cuprammonia fiber has a wavelength of 1650 cm -1 The absorption peaks at the left and right positions weaken significantly at 150°C; wave number 1600cm -1 The absorption peaks at the left and right positions begin to appear at 150°C.

[0066] The corresponding relationship between the infrared absorption peaks of the lyocell fiber and cuprammonium fiber reference samples obtained in Example 1 and Example 2 and the mid-infrared spectrum frequency and temperature is shown in Table 1.

[0067] Table 1 Correspondence between infrared absorption peaks and mid-infrared spectrum frequencies and temperatures of lyocell fiber and cuprammonium fiber reference samples

[0068]

[0069] Example 3

[0070] It is known that the fiber to be identified is one of lyocell fiber or cupro fiber, and the type of fiber to be identified is qualitatively identified. The specific method is as follows:

[0071] Sample preparation: Use a Hasse slicer to cut 1g of the fiber to be identified into fiber samples with a length of 0.1mm;

[0072] Preparation of transparent thin sheets: 0.1 mg of the fiber sample was mixed evenly with 20 mg of dry spectrally pure potassium bromide crystals and placed on a tablet press and pressed into transparent thin sheets at a pressure of 8 MPa;

[0073] The transparent sheet was placed in the window of Nicolet 380 Fourier transform infrared spectrometer (heatable);

[0074] The heating rate of the Nicolet 380 Fourier transform infrared spectrometer was set to 15°C / min, and the temperature was raised from room temperature to 500°C, and the infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample were continuously recorded at every 25°C.

[0075] The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at 25°C were compared with the infrared spectra of the molecular thermal motion and thermal decomposition of the lyocell reference sample and the cuprammonium fiber reference sample obtained by the methods of Example 1 and Example 2, respectively. -1 Position and wave number 1600cm -1 The absorption peak characteristics at different temperatures at different locations are compared and analyzed to determine whether the fiber to be identified is cuprammonium fiber or lyocell fiber. -1 The absorption peaks at the left and right positions weakened significantly at 150°C, with a wave number of 1600cm -1The absorption peaks at the left and right positions begin to appear at 150°C, which means the fiber to be identified is cuprammonium fiber; if the absorption peaks at the wave number 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 300°C, with a wave number of 1600 cm -1 If the absorption peaks on the left and right begin to appear at 300°C, it can be determined that the fiber to be identified is Lyocell fiber.

[0076] Example 4

[0077] The difference from Example 3 is that:

[0078] Sample preparation: Use a Hasse slicer to cut 0.1g of the fiber to be identified into a fiber sample with a length of 0.01mm;

[0079] Preparation of transparent sheets: 0.2 mg of the fiber sample was mixed evenly with 30 mg of dry spectrally pure potassium bromide crystals and placed on a tablet press to press into transparent sheets at a pressure of 9 MPa;

[0080] The heating rate of the Nicolet 380 Fourier transform infrared spectrometer was set to 25°C / min, and the temperature was raised from room temperature to 500°C, and the infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample were continuously recorded at every 50°C.

[0081] The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at every 50°C were compared with the infrared spectra of the molecular thermal motion and thermal decomposition of the lyocell reference sample and the cuprammonium fiber reference sample obtained by the methods of Example 1 and Example 2, respectively. If the infrared spectra obtained by comparison are at a wave number of 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 150°C, with a wave number of 1600cm -1 The absorption peaks at the left and right positions begin to appear at 150°C, which means the fiber to be identified is cuprammonium fiber; if the absorption peaks at the wave number 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 300°C, with a wave number of 1600 cm -1 If the absorption peaks on the left and right begin to appear at 300°C, it can be determined that the fiber to be identified is Lyocell fiber.

[0082] Example 5

[0083] The difference from Example 3 is that:

[0084] Sample preparation: Use a Hastelloy slicer to cut 0.2g of the fiber to be identified into a fiber sample with a length of 0.05mm;

[0085] Preparation of transparent thin sheets: 1 mg of the fiber sample was mixed evenly with 40 mg of dry spectrally pure potassium bromide crystals and placed on a tablet press to press into transparent thin sheets at a pressure of 10 MPa;

[0086] The heating rate of the Nicolet 380 Fourier transform infrared spectrometer was set to 30°C / min, and the temperature was raised from room temperature to 500°C, and the infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample were continuously recorded at every 50°C.

[0087] The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at 50°C were compared with the infrared spectra of the molecular thermal motion and thermal decomposition of the lyocell reference sample obtained by the methods of Example 1 and Example 2. If the infrared spectra obtained by comparison are at a wave number of 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 150°C, with a wave number of 1600cm -1 The absorption peaks at the left and right positions begin to appear at 150°C, which means the fiber to be identified is cuprammonium fiber; if the absorption peaks at the wave number 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 300°C, with a wave number of 1600 cm -1 If the absorption peaks on the left and right begin to appear at 300°C, it can be determined that the fiber to be identified is Lyocell fiber.

[0088] Example 6

[0089] The difference from Example 3 is that:

[0090] Sample preparation: Use a Hasse slicer to cut 0.8g of the fiber to be identified into a fiber sample with a length of 0.03mm;

[0091] 0.5 mg of the fiber sample was mixed evenly with 40 mg of dry spectrally pure potassium bromide crystals and placed on a tablet press and pressed into a transparent sheet at a pressure of 9 MPa;

[0092] The heating rate of the Nicolet 380 Fourier transform infrared spectrometer was set to 20°C / min, and the temperature was raised from room temperature to 500°C, and the infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample were continuously recorded at every 50°C.

[0093] The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at 50°C are compared with the infrared spectra of the molecular thermal motion and thermal decomposition of the lyocell reference sample obtained by the methods of Example 1 and Example 2. If the infrared spectra obtained by comparison are at a wave number of 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 150°C, with a wave number of 1600cm -1The absorption peaks at the left and right positions begin to appear at 150°C, which means the fiber to be identified is cuprammonium fiber; if the absorption peaks at the wave number 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 300°C, with a wave number of 1600 cm -1 If the absorption peaks on the left and right begin to appear at 300°C, it can be determined that the fiber to be identified is Lyocell fiber.

[0094] The technical solutions represented by the above embodiments of the present invention do not use any solvents such as acid and alkali solutions, and no harmful substances such as wastewater will be discharged during the identification process, so it has environmentally friendly characteristics. Secondly, the main time of the identification operation is the heating time of the Nicolet 380 Fourier transform infrared spectrometer, taking the heating rate of 20℃ / min as an example, from room temperature 25℃ to 500℃, and then the infrared spectrometer automatically generates the infrared spectrum of the fiber sample to be identified and compares and analyzes the existing infrared spectrum of the lyocell fiber reference sample and the infrared spectrum of the cuprammonium fiber reference sample, and the total time required is less than 30min. In the fiber component analysis, 0.1-1g of sample belongs to a large amount, and the sample amount used in the common fiber thermal analysis experiment or spectral experiment is 1-10mg; in addition, the large amount here also refers to the number of fibers, usually hundreds of fibers, which also reflects the integrity and representativeness of the sample, avoiding the defect that a single sample is not representative. Since a large number of fiber samples are used for the experiment, the experimental results are representative, so there is no need to repeat the infrared absorption spectrum test many times. In summary, the technical solution of the present application is aimed at the fiber to be identified that is either lyocell fiber or cupro fiber, and has the advantages of high efficiency, accuracy and environmental protection. The inventors conducted repeated, large-scale and multiple tests (including blind selection tests) on samples of cupro fiber and lyocell fiber provided by fiber manufacturers or textile enterprises, and verified that the identification results were consistent with the actual types of the products, and the repeatability of the identification accuracy was also consistent. The accuracy rate obtained by the identification method was as high as 100%.

[0095] Finally, it should be noted that although the above embodiments have been described in the specification and drawings of this application, this does not limit the scope of patent protection of this application. All technical solutions generated by replacing or modifying equivalent structures or equivalent processes based on the essential concept of this application using the contents recorded in the specification and drawings of this application, as well as directly or indirectly implementing the technical solutions of the above embodiments in other related technical fields, are included in the scope of patent protection of this application.

Claims

1. A qualitative identification method for cuprammonia fiber and lyocell fiber, characterized in that: The following steps are involved: Sample preparation: Cut the fiber to be identified into fiber samples; Preparation of transparent sheet: the fiber sample and the window sheet material are mixed evenly, and then placed on a sheet press to be pressed into a transparent sheet; The transparent sheet is placed in a temperature-elevable device and in front of the infrared spectrometer window; The infrared spectrometer is heated to 500° C. to record infrared spectra of thermal motion and thermal decomposition of the fiber sample molecules at preset interval temperature points; The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at the preset interval temperature points are compared with the infrared spectra of the molecular thermal motion and thermal decomposition of the reference sample. The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at the preset interval temperature points are compared with the infrared spectra of the molecular thermal motion and thermal decomposition of the reference sample. -1 Position and 1600cm -1 The absorption peak characteristic comparison analysis results at the position determine whether the fiber to be identified is cuprammonium fiber or lyocell fiber.

2. The qualitative identification method of cuprammonium fiber and lyocell fiber according to claim 1, characterized in that: When the temperature-increasing device is heated to 500° C., the heating rate is 10-30° C. / min.

3. The qualitative identification method of cuprammonium fiber and lyocell fiber according to claim 1, characterized in that: The preset interval temperature points are 10°C-100°C.

4. The qualitative identification method of cuprammonium fiber and lyocell fiber according to claim 1, characterized in that: The window material is potassium bromide.

5. The qualitative identification method of cuprammonium fiber and lyocell fiber according to claim 4, characterized in that: In the transparent sheet preparation step, 0.1-1 mg of the fiber sample is mixed with 20-40 mg of the window sheet material.

6. The qualitative identification method of cuprammonium fiber and lyocell fiber according to claim 1, characterized in that: The pressure when the transparent sheet is pressed on a tablet press is 8-10 MPa.

7. The qualitative identification method of cuprammonium fiber and lyocell fiber according to claim 1, characterized in that: The length of the fiber sample is 0.01-0.1 mm.

8. The qualitative identification method of cuprammonium fiber and lyocell fiber according to claim 1, characterized in that: The reference samples include a cuprammonia fiber reference sample and a lyocell fiber reference sample. The infrared spectra of the molecular thermal motion and thermal decomposition of the fiber sample at the preset interval temperature points are compared and analyzed with the infrared spectra of the molecular thermal motion and thermal decomposition of the reference sample. The cuprammonia fiber reference sample has a wavelength of 1650 cm -1 The absorption peak at the position is significantly weakened at 150℃, with a wave number of 1600cm -1 The absorption peak at the position begins to appear at 150°C; the Lyocell fiber reference sample has an absorption peak at a wave number of 1650cm -1 The absorption peaks at the left and right positions weakened significantly at 300°C, with a wave number of 1600 cm -1 The absorption peaks at the left and right positions begin to appear at 300°C; the identification result of the fiber to be identified is obtained based on the comparison and analysis results.

9. Use of the qualitative identification method of cuproammonia fiber and lyocell fiber according to any one of claims 1 to 8 in identifying and distinguishing cuproammonia fiber and lyocell fiber.

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