Composite anti-counterfeiting fiber with different colors and different segments on front and back as well as preparation method and application of composite anti-counterfeiting fiber

Abstract

The invention belongs to the technical field of anti-counterfeiting fibers, provides a front and back different-color and different-section composite anti-counterfeiting fiber and a preparation method and application thereof, and aims to solve the problems of regularization of anti-counterfeiting characteristics, simplification of information dimensions and insufficient anti-counterfeiting levels caused by periodic dependence of a production process of existing anti-counterfeiting fibers. The anti-counterfeiting fiber is characterized in that the anti-counterfeiting fiber has a non-circular cross section contour, the front and back areas of the anti-counterfeiting fiber respectively present front and back heterochromatic chromatographic matrixes which are distributed aperiodically along the axial direction, and a functional anti-counterfeiting material is dispersed and distributed in at least one color section; according to the preparation method, a double-channel independent aperiodic signal system based on chaotic signal modulation is adopted, and multi-channel space partition co-extrusion molding is carried out. By adopting the technical scheme, the complexity and uncertainty of the anti-counterfeiting feature can be remarkably improved, reverse engineering cracking is effectively prevented, and the anti-counterfeiting safety is improved.

Description

Technical Field

[0001] This invention belongs to the field of anti-counterfeiting fiber technology, specifically relating to a composite anti-counterfeiting fiber with different colors and segments on the front and back, its preparation method, and its application. Background Technology

[0002] In modern commodity circulation and identity authentication systems, the advancement and reliability of anti-counterfeiting technology are the cornerstones of maintaining market order and social credit. Anti-counterfeiting fibers, as an embedded, endogenous anti-counterfeiting technology element, play a crucial role in high-security applications due to their integrated molding with the substrate (usually paper or polymer). This makes them difficult to peel off, replace, or replicate. Early anti-counterfeiting fibers primarily achieved this by incorporating short fibers of a single color into the substrate, using the presence or absence of the fiber or a specific color as the first line of defense for authenticity verification. With technological advancements, segmented coloring anti-counterfeiting fibers were developed to enhance anti-counterfeiting levels. Specifically, this technology typically employs a single-channel intermittent coloring extrusion process, creating an alternating structure of colored and colorless segments (or two different colors) along the fiber's axial direction. This segmented feature, compared to single-color fibers, provides more complex visual identification information, and its production process demands higher equipment precision. During a specific historical period, this effectively raised the barrier to counterfeiting and reduced costs, constituting the mainstream anti-counterfeiting fiber solution at the time.

[0003] However, with the continuous advancement of global manufacturing technology and information analysis capabilities, especially the widespread adoption of precision imitation and reverse engineering capabilities, the inherent technical limitations of the aforementioned anti-counterfeiting fibers based on the single-channel, periodic coloring principle are becoming increasingly apparent. They are gradually finding it difficult to meet the current and future stringent requirements for anti-counterfeiting technology, which are characterized by multiple layers, dynamics, and uncertainties. The reason for this lies in a deep-seated technical contradiction within the design philosophy and implementation path of this technical solution: the inherent conflict between the stability of the production process and the complexity of the anti-counterfeiting features. On the one hand, to ensure the physical properties of the fiber (such as diameter uniformity and tensile strength) and production efficiency, the single-channel extrusion process logically tends to adopt a highly regularized, periodic control mode. Stable and repeatable parameter settings, whether for the timing of pigment injection, duration, or switching interval, are prerequisites for achieving large-scale production and ensuring product yield. This reliance on "regularity" directly leads to the prepared anti-counterfeiting fibers exhibiting a high degree of periodicity or easily deducible quasi-periodicity in terms of segment length and arrangement sequence. For counterfeiters, simply taking a small sample of fiber and analyzing it under a microscope and images allows them to relatively easily crack the mathematical model or arrangement of its segments, thus significantly lowering the technical barrier to counterfeiting. On the other hand, high-level anti-counterfeiting requires its features to possess "non-determinism" and "complexity," meaning it's difficult to predict the whole from a localized observation, and also difficult to describe using simple mathematical logic. This implies that while pursuing production stability, traditional processes inadvertently sacrifice the core randomness and complexity of anti-counterfeiting features, creating a theoretically insurmountable upper limit to their security level.

[0004] Furthermore, this technological contradiction also lies in the singularity of anti-counterfeiting information dimensions. Traditional single-channel processes essentially perform one-dimensional color coding on a single viewing surface of the fiber (i.e., the entire outer surface of a cylindrical fiber). Regardless of the viewing angle, the color segmentation information presented by the fiber is completely identical—a static, one-dimensional anti-counterfeiting feature. In modern anti-counterfeiting concepts, dynamic or multi-dimensional information verification (such as color changes at specific angles, information differences between the front and back sides, etc.) is considered a more difficult-to-crack "live" feature. Existing anti-counterfeiting fibers clearly lack this multi-dimensional information carrying capacity. In addition, their anti-counterfeiting information is usually limited to the visible light range, relying on the human eye or ordinary optical equipment for identification. For multi-layered anti-counterfeiting systems integrating stealth features (such as ultraviolet fluorescence, infrared absorption / excitation, etc.), traditional single-channel processes struggle to precisely and segmentally composite different types of functional materials into the fiber structure without significantly affecting the performance and color performance of the main fiber. This limitation in anti-counterfeiting dimensions makes it particularly vulnerable in high-end authentication scenarios equipped with multispectral analysis equipment.

[0005] Therefore, existing anti-counterfeiting fiber technologies are limited by their core process principle of single-channel, periodic coloring. This results in easily predictable segmented structures, a lack of dimensionality in visual features, and a lack of concealed information beyond visible light in terms of anti-counterfeiting layers. These inherent limitations constitute the fundamental technical bottleneck preventing them from meeting the demands of next-generation high-security anti-counterfeiting technologies. Thus, how to break through the constraints of traditional process frameworks, achieve highly non-periodic color segmentation in the design of fiber microstructures, heterogeneous visual information on the front and back viewing surfaces, and simultaneously integrate multiple invisible anti-counterfeiting features with different physical mechanisms to construct a multi-dimensional, multi-layered, static and dynamic composite anti-counterfeiting system has become a key challenge and an urgent technical problem for those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to overcome the technical defects of existing anti-counterfeiting fibers, which suffer from regularized anti-counterfeiting features, limited information dimensions, and insufficient anti-counterfeiting layers due to the periodic dependence of their production processes. To achieve this goal, this invention provides a composite anti-counterfeiting fiber with different colors and segments on the front and back sides, a method for its preparation, and its application, which possesses high complexity and non-determinism in microstructure, information dimensions, and generation logic. The core of this technical solution lies in constructing a spatial partitioning co-extrusion system modulated by dual independent non-periodic signals. This system simultaneously realizes, on a single fiber, a non-periodic segmented color sequence along its axial direction driven by a chaotic algorithm, and a stable front and back side color information structure formed by physical partitioning on its cross-section. Furthermore, it organically integrates various invisible anti-counterfeiting features with different physical mechanisms within this multi-dimensional heterogeneous structure, thereby fundamentally resolving the inherent contradiction between the stability of the production process and the complexity of the anti-counterfeiting features.

[0007] To achieve the above-mentioned objectives, this invention provides a composite anti-counterfeiting fiber with different colors and segments on the front and back: The fiber has a longitudinal axis extending along its length, and its structural feature is that the fiber has a predetermined non-circular cross-sectional profile, the boundary of which spatially defines at least one frontal viewing area and one back viewing area. The front observation area is presented as a front color spectrum matrix along the longitudinal axis. The front color spectrum matrix is ​​composed of at least three front color segments with different visible light colors arranged in sequence, and the length sequence of each front color segment presents a non-periodic distribution. The back observation area is presented as a back color spectrum matrix along the longitudinal axis. The back color spectrum matrix is ​​composed of at least two back color segments that are different from all the color types of the front color segments and are arranged in sequence. The length sequence of each back color segment presents a non-periodic distribution independent of the length sequence of the front color segments. Furthermore, in the front chromatographic matrix and the back chromatographic matrix, a functional anti-counterfeiting material is uniformly dispersed within at least one designated color segment. The functional anti-counterfeiting material is selected from at least one of ultraviolet fluorescent materials, infrared absorbing materials, infrared excitation materials, magnetic responsive materials, or any combination thereof.

[0008] In a preferred embodiment of the present invention, the matrix material of the fiber is a thermoplastic polymer with high transparency and high mechanical strength. Specifically, the thermoplastic polymer is polyethylene terephthalate (PET), polyvinyl alcohol (PVA), polypropylene (PP), or polyamide (PA), with an intrinsic viscosity of 0.60 dL / g to 0.85 dL / g, to ensure the spinnability of the fiber and its final mechanical properties during the subsequent stretching and orientation process.

[0009] Furthermore, the non-circular cross-sectional profile is set as an equilateral triangle. This equilateral triangular cross-sectional structure physically divides the fiber surface into three continuous, macroscopically flat observation surfaces. Any two adjacent observation surfaces are collectively defined as the front observation area, and the remaining observation surface is defined as the back observation area. This structural design not only ensures the physical isolation of front and back information, avoiding visual information overlap caused by the cylindrical structure of the fiber, but also, when the fiber is embedded in a substrate such as paper, the randomness of the orientation of its different observation surfaces further increases the complexity of the macroscopic anti-counterfeiting pattern.

[0010] Specifically, the front color spectrum matrix consists of a first front color segment, a second front color segment, and a third front color segment, with colors of red, blue, and green, respectively. The back color spectrum matrix consists of a first back color segment and a second back color segment, with colors of yellow and purple, respectively. These five colors are defined in CIE 1976 L. a The b* color space exhibits significant differentiation, ensuring clear recognition by the human eye. Each color segment is formed by blending a colorant masterbatch containing specific pigments or dyes with a matrix polymer. The red is formed by melt blending 1.5% by mass of CI Pigment Red 170 with the matrix polymer; the blue is formed by melt blending 1.2% by mass of CI Pigment Blue 15:3 with the matrix polymer; the green is formed by melt blending 2.0% by mass of CI Pigment Green 7 with the matrix polymer; the yellow is formed by melt blending 1.8% by mass of CI Pigment Yellow 139 with the matrix polymer; and the purple is formed by melt blending 2.5% by mass of CI Pigment Violet 23 with the matrix polymer.

[0011] As a core technical feature of this invention, the aperiodic distribution of the length sequences of the front and back color segments is generated through a deterministic chaotic algorithm. Specifically, the selection of the type and length of the front color segment is determined by the output sequence of a first chaotic dynamic system; the selection of the type and length of the back color segment is determined by the output sequence of a second chaotic dynamic system with parameters different from the first chaotic dynamic system. This control logic based on a deterministic chaotic system ensures the absolute repeatability of the production process under given initial parameters. Simultaneously, the inherent aperiodicity of its output sequence and its extreme sensitivity to initial conditions endow the anti-counterfeiting fiber with complex cryptographic properties that make it extremely difficult to reverse engineer. The length of each color segment is controlled within the range of 0.5 mm to 8.0 mm.

[0012] Furthermore, the integration of the functional anti-counterfeiting material involves uniquely binding it to a specific color segment. As one implementation, a long-wave ultraviolet fluorescent material is additionally added to the colorant masterbatch of the first front color segment (red). This long-wave ultraviolet fluorescent material is a rare-earth phosphor based on europium (Eu³⁺) organic complexes, with an average particle size of 1.0 to 3.0 micrometers, and an addition mass fraction of 0.8% in the matrix polymer. Under ultraviolet light excitation at a wavelength of 365 nanometers, this material emits a narrow-band red fluorescence with a peak wavelength of 612 nanometers, which visually enhances the red color of the color segment itself. Simultaneously, a near-infrared absorbing material is additionally added to the colorant masterbatch of the first back color segment (yellow). This near-infrared absorbing material is a metal phthalocyanine derivative, with its maximum absorption peak in the polymer matrix located at a wavelength of 880 nanometers ± 5 nanometers and a half-width of less than 30 nanometers. The material, added at a mass fraction of 1.2% to the matrix polymer, exhibits strong absorption characteristics in the near-infrared spectrum, while producing no additional color shift in the visible light range and not affecting its inherent yellow appearance. This binding integration achieves precise point-to-point correlation between visible light information and latent spectral information, constructing a multi-layered verification logic.

[0013] This invention also provides a method for preparing the above-mentioned front and back color-different segment composite anti-counterfeiting fiber. This method abandons the traditional single-channel intermittent coloring process and instead adopts a multi-channel spatial partition co-extrusion molding process based on chaotic signal modulation, which specifically includes the following steps: S1: Preparation of a diversified masterbatch system This step aims to prepare high-concentration masterbatches with different functions for subsequent co-extrusion. Specifically, it includes: (1) Preparation of matrix polymer masterbatch: PET chips with intrinsic viscosity of 0.60 dL / g to 0.85 dL / g were vacuum dried at 140°C for 12 hours; (2) Preparation of multiple colorant masterbatches: CI pigment red 170, CI pigment blue 15:3, CI pigment green 7, CI pigment yellow 139 and CI pigment purple 23 pigment powders were mixed with the matrix PET carrier resin through a co-rotating twin-screw extruder at a temperature of 260°C to 280°C to obtain high-concentration colorant masterbatches with a pigment content of 25% to 40%. (3) Preparation of functional masterbatch: europium (Eu³⁺) organic complex phosphor with an average particle size of 1.0 micrometer to 3.0 micrometer and metal phthalocyanine derivative powder with a strong absorption peak at 880 nanometer are melt-blended and granulated with the matrix PET carrier resin through the aforementioned twin-screw extruder under mild shear conditions (screw speed less than 150 rpm) to obtain functional masterbatch with a functional material content of 10% to 20% to avoid performance degradation of functional materials during processing.

[0014] S2: Generation and Mapping of Chaotic Control Sequences This step is the control core of the method of the present invention, used to generate non-periodic color segment switching instructions, specifically including: (1) Construct the first chaotic signal generator, which adopts a Logistic Map defined by the formula x_{n+1} = r * x_n * (1 -x_n), sets its chaotic parameter r to 3.98, and the initial value x0 to 0.2135. The generator continuously generates an aperiodic floating-point sequence {x_n}. (2) Construct a second chaotic signal generator, which also uses the logistic mapping, but sets its chaotic parameter s to 3.92 and its initial value y0 to 0.7856, thereby generating another aperiodic floating-point sequence {y_n} that is completely independent of the former. (3) Establish the mapping rules from output sequence to physical control.

[0015] For the positive color segment, the numerical interval [0, 1] of the sequence {x_n} is divided into three equal parts. If 0 ≤ x_n < 1 / 3, the metering pump controlling the supply of red masterbatch is activated; if 1 / 3 ≤ x_n < 2 / 3, the metering pump controlling the supply of blue masterbatch is activated; if 2 / 3 ≤ x_n ≤ 1, the metering pump controlling the supply of green masterbatch is activated. At the same time, the duration T_x of this pumping is determined by the formula T_x = T_base + k_x * x_n, where T_base is the base pumping time (0.1 seconds) and k_x is the length adjustment coefficient. For the back color segment, the numerical interval [0, 1] of the sequence {y_n} is bisected. If 0 ≤ y_n < 1 / 2, the metering pump controlling the supply of yellow masterbatch is activated; if 1 / 2 ≤ y_n ≤ 1, the metering pump controlling the supply of purple masterbatch is activated. The pumping duration T_y is also determined by a similar formula T_y = T_base + k_y * y_n. This step transforms the abstract mathematical sequence into precise, non-periodic timing control of different material flows.

[0016] S3: Spatial partitioning co-extrusion molding This step involves spatially merging different material flows into a single fiber with a specific cross-sectional structure, specifically including: (1) Set up a multi-channel co-extrusion system, which includes at least six independent precision metering pumps for conveying the matrix PET melt, three front colorant masterbatch melts, two back colorant masterbatch melts, and functional masterbatch melts bound to a specific color; (2) Design and use a composite spinning assembly with a Y-shaped internal partition channel, which physically divides the circular channel inside the assembly into three independent fan-shaped regions. (3) According to the control sequence generated by S2, the selected front color melt (e.g., the melt after mixing red colorant masterbatch melt and ultraviolet fluorescent masterbatch melt in a preset ratio) is mixed with the base PET melt and injected into two adjacent fan-shaped areas defined by the Y-shaped partition; at the same time, the selected back color melt (e.g., the melt after mixing yellow colorant masterbatch melt and infrared absorption masterbatch melt in a preset ratio) is mixed with the base PET melt and injected into the remaining fan-shaped area; All material melts converge inside the composite spinning assembly at a temperature of 285°C and form composite nascent fibers with a stable equilateral triangular cross section and a clear physical interface when they leave the spinneret. S4: Fiber post-treatment and setting This step aims to endow the fiber with excellent physical properties and a stable microstructure, specifically including: (1) Cooling and curing: After the nascent filament leaves the spinneret, it passes through a lateral blowing cooling device to rapidly reduce its temperature to below the glass transition temperature, thus completing the initial curing. (2) Stretching and orientation: The cured filaments are passed through a stretching zone consisting of multiple sets of heating rollers with different speed ratios. The filaments are stretched at a stretching ratio of 4.0 to 5.5 in a temperature environment of 90°C to 110°C, so that the polymer macromolecules inside the fiber are highly oriented along the axial direction, thereby significantly improving the tensile strength and modulus of the fiber. (3) Heat setting treatment: the stretched fiber is passed through a heat setting zone of 160°C to 180°C and a constant micro-tension is applied and held for 3 to 5 seconds to eliminate the internal stress generated during the stretching process, stabilize the crystalline structure and dimensional accuracy of the fiber, and prevent subsequent shrinkage. S5: Finished product winding The heat-set, stable continuous filaments are wound onto a bobbin under constant tension using a winding head to form the final product. The final fineness of the resulting fibers is 3.0 dtex to 6.0 dtex.

[0017] This invention also provides an application of the aforementioned front-and-back different-color and different-segment composite anti-counterfeiting fiber. Specifically, the application includes: cutting the continuous filament fiber into short fibers with a length of 3 mm to 5 mm, and then adding the short fibers to the pulp of high-security paper (such as securities, passports, and certificates) at a mass ratio of 0.5% to 2.0% of the dry weight of the pulp. During the papermaking process, the fibers are uniformly mixed with the pulp fibers to form an embedded, randomly distributed anti-counterfeiting feature. Alternatively, the continuous filament fiber can be directly used as a security thread, embedded into the paper or polymer substrate in a windowed or fully embedded manner through a specific embedding process.

[0018] The beneficial effects of this invention are: (1) The fiber prepared by the present invention through precise stretching orientation and heat setting process has higher breaking strength and lower boiling water shrinkage, showing excellent mechanical properties and dimensional stability, which is mainly attributed to the multi-stage treatment in step S4.

[0019] (2) The color segments of the fibers of the present invention are in CIE L a The b* color space has clear coordinates and significant color differences, making it easy to distinguish visually. Meanwhile, its integrated functional materials exhibit precise and strong response signals: the red segment has a clear 612nm emission peak under 365nm ultraviolet light, and the yellow segment has a clear 881nm absorption peak in the near-infrared spectral region, confirming the successful construction of multi-layered anti-counterfeiting features.

[0020] (3) The segment length distribution of the fiber of the present invention exhibits typical chaotic system characteristics, and its spectrum is a continuous broadband spectrum, proving its non-periodicity. In contrast, the segment length sequence of the fiber of the traditional process has extremely strong periodicity, and its spectral characteristics are clear and easy to analyze and reproduce.

[0021] (4) The multi-dimensional anti-counterfeiting features integrated in the fiber of the present invention (different colors on the front and back, non-periodic segmentation, ultraviolet fluorescence, and infrared absorption) can all be accurately and unambiguously identified by the corresponding detection equipment, forming a three-dimensional anti-counterfeiting system that is mutually corroborated from open to semi-concealed to fully concealed.

[0022] This invention, through a systematic innovation—introducing chaotic control theory to guide the microstructure generation of anti-counterfeiting fibers and combining it with spatial partitioning co-extrusion technology—successfully prepares a composite anti-counterfeiting fiber with unprecedented complexity and security in color layout, geometric structure, and spectral response. This technical solution not only achieves a qualitative leap in product structure but also resolves the fundamental contradictions of existing technologies at the underlying logic of the preparation method, greatly raising the threshold for anti-counterfeiting technology and possessing significant creative and industrial practical value. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of this invention, the present application will be further described in detail below with reference to embodiments. Example

[0024] This embodiment uses the method disclosed in this invention to prepare the front and back color-different segment composite anti-counterfeiting fiber.

[0025] S1. PET chips with an intrinsic viscosity of 0.8 dL / g were selected as the matrix material and vacuum-dried at 140℃ for 16 hours. PET-based colorant masterbatches for CI pigments Red 170, Blue 15:3, Green 7, Yellow 139, and Violet 23 were prepared, each with a pigment content of 30%. Ultraviolet fluorescent masterbatch based on Eu(TTA)3(Phen) (fluorescent powder content 15%) and infrared absorption masterbatch based on vanadium oxyphthalocyanine (absorbent content 12%) were prepared separately.

[0026] S2. The control system uses logical stochastic mapping. The first path parameter is set to r=3.98, x0=0.2135; the second path parameter is set to s=3.92, y0=0.7856. The front-side color mapping rule is [0, 1 / 3) corresponds to red, [1 / 3, 2 / 3) corresponds to blue, and [2 / 3, 1] corresponds to green. The back-side color mapping rule is [0, 1 / 2) corresponds to yellow, and [1 / 2, 1] corresponds to purple.

[0027] S3. A Y-shaped internally partitioned composite spinning assembly is used, with the spinneret orifice being an equilateral triangle with a side length of 0.3 mm. When the red segment is generated, the melt of the PET matrix, red masterbatch, and fluorescent masterbatch is injected into the front flow channel in proportion; when the yellow segment is generated, the melt of the PET matrix, yellow masterbatch, and infrared absorbing masterbatch is injected into the back flow channel in proportion. The spinning temperature is 285℃.

[0028] S4. After the nascent yarn is cooled by lateral air at 20°C, it undergoes two stages of stretching. The first stage is stretched 2.8 times at 95°C, and the second stage is stretched 1.7 times at 110°C, with a total stretch ratio of 4.76. It is then heat-set at 170°C for 4 seconds.

[0029] S5. Finally, the finished fiber with an average fineness of 4.52 dtex is obtained by winding. Example

[0030] This embodiment uses the method disclosed in this invention to prepare the front and back color-different segment composite anti-counterfeiting fiber.

[0031] S1. PET chips with an intrinsic viscosity of 0.7 dL / g were selected as the matrix material and vacuum-dried at 145℃ for 14 hours. PET-based colorant masterbatches for CI pigments Red 170, Blue 15:3, Green 7, Yellow 139, and Violet 23 were prepared, each with a pigment content of 28%. Ultraviolet fluorescent masterbatch based on Eu(TTA)3(Phen) (fluorescent powder content 12%) and infrared absorption masterbatch based on vanadium oxyphthalocyanine (absorbent content 10%) were prepared separately.

[0032] S2. The control system uses logical stochastic mapping. The first path parameter is set to r=3.95, x0=0.251; the second path parameter is set to s=3.89, y0=0.7237. The front-side color mapping rule is [0, 1 / 3) corresponds to red, [1 / 3, 2 / 3) corresponds to blue, and [2 / 3, 1] corresponds to green. The back-side color mapping rule is [0, 1 / 2) corresponds to yellow, and [1 / 2, 1] corresponds to purple.

[0033] S3. A Y-shaped internally partitioned composite spinning assembly is used, with the spinneret orifice being an equilateral triangle with a side length of 0.3 mm. When the red segment is generated, the melt of the PET matrix, red masterbatch, and fluorescent masterbatch is injected into the front flow channel in proportion; when the yellow segment is generated, the melt of the PET matrix, yellow masterbatch, and infrared absorbing masterbatch is injected into the back flow channel in proportion. The spinning temperature is 28℃.

[0034] S4. After the nascent yarn is cooled by lateral air at 20°C, it undergoes two-stage stretching: the first stage is stretched 3.0 times at 100°C, and the second stage is stretched 1.6 times at 15°C, with a total stretch ratio of 4.81. It is then heat-set at 165°C for 5 seconds.

[0035] S5. Finally, the finished fiber with an average fineness of 4.0 dtex is obtained by winding.

[0036] Comparative Example 1 This comparative example uses a traditional single-channel intermittent coloring process to prepare a segmented colored fiber, aiming to simulate existing technology.

[0037] A single PET melt stream is used, through a valve controlled by a simple time relay, to periodically inject red and blue colorant melts into the main channel. The control logic is: inject red melt for 1.0 second, stop injection (forming a colorless segment) for 1.0 second, inject blue melt for 1.0 second, stop injection for 1.0 second, and repeat this cycle. The fibers are extruded through a standard circular spinneret, with a low overall draw ratio (3.0 times) and without sufficient heat setting.

[0038] Comparative Example 2 This comparative example uses a traditional two-color periodic coloring process to prepare a segmented colored fiber, aiming to simulate existing technology.

[0039] PET chips with an intrinsic viscosity of 0.70 dL / g were used, and the drying conditions were the same as in Example 1. Only red and blue colorant masterbatches were prepared, with a pigment content of 30%. A fixed time interval was used for control: red melt injection for 1.5 seconds, then switching to blue melt injection for 1.5 seconds, and repeating this cycle. The fibers were extruded through circular spinnerets without functional material integration. Single-stage stretching: stretched 3.2 times at 95°C. Heat setting conditions: treated at 155°C for 3 seconds. The final wound yielded finished fibers with an average fineness of 4.5 dtex.

[0040] To further quantify the technical effects of the embodiments and comparative examples of the present invention, a series of standardized tests were conducted, and the results are summarized in Tables 1 to 4.

[0041] Table 1 Comparison of fiber physical properties As clearly shown in Table 1, the embodiment, through precise two-stage stretching orientation and thorough heat setting (step S4), achieved a breaking strength of 4.85-5.1 cN / dtex, significantly higher than the comparative example's 3.05-3.12 cN / dtex, demonstrating superior mechanical properties. Simultaneously, its boiling water shrinkage rate was only 1.8-1.5%, indicating extremely high dimensional stability, crucial for long-term applications in substrates such as paper. In contrast, the comparative example exhibited lower strength and higher shrinkage due to process limitations.

[0042] Table 2 Quantification of fiber color and spectral properties in Example 1 The data in Table 2 quantitatively confirm the successful construction of the fiber multidimensional features of this invention. (In CIE 1976 L) aIn the b* color space, the coordinates of the five color segments are far apart, indicating significant color differences that are easily distinguishable by the human eye or machine vision. More importantly, the integrated functional materials exhibit precise and strong response signals: the red segment, under 365nm ultraviolet light excitation, has a clear and high-intensity fluorescence emission peak at 612nm; the yellow segment has a clear absorption peak with an absorbance as high as 0.85 at 881nm in the near-infrared spectral region. This proves that the technical solution of precisely binding visible light information with implicit spectral information is entirely feasible and highly effective.

[0043] Table 3. Aperiodic analysis of color segment length sequences The results in Table 3 irrefutably demonstrate the superiority of this invention in terms of anti-counterfeiting feature logic. Fast Fourier Transform analysis of the front color segment length sequence of the fiber in Example 1 reveals a typical continuous broadband noise pattern in its spectrum, a hallmark of chaotic system output sequences, strongly proving its non-periodicity. In contrast, the fixed-length sequence in Comparative Example 1 exhibits extremely strong, isolated peaks at frequencies corresponding to its spatial period; this periodicity is easily analyzed and replicated.

[0044] Table 4 Integrated Anti-counterfeiting Feature Verification The comprehensive verification results in Table 4 show that the multi-dimensional anti-counterfeiting features integrated into the fiber of this invention, including the open-level front and back color difference and non-periodic segmentation features, the semi-concealed level ultraviolet fluorescence features, and the fully concealed level infrared absorption machine-readable features, can all be accurately and unambiguously identified by the corresponding detection methods, forming a three-dimensional anti-counterfeiting system that is mutually corroborative and logically closed-loop from public recognition to professional identification.

[0045] In summary, this invention, through comprehensive and systematic innovation in fiber microstructure, color layout logic, functional material integration methods, and core preparation processes, successfully solves the fundamental defects of existing anti-counterfeiting fibers, such as their singular features and ease of replication. It provides a high-end composite anti-counterfeiting fiber with unprecedented complexity, security, and industrial practical value, as well as its implementation method.

Claims

1. A positive-backside dichroic segmented composite security fiber having a longitudinal axis extending along its length direction, characterized in that: the fiber has a preset non-circular cross-sectional profile, the boundary of which spatially defines at least one positive viewing area and one backside viewing area; the positive viewing area presents a positive color spectrum matrix along the longitudinal axis, which is composed of at least three positive color segments of visibly different colors arranged in sequence, the sequence of the length of each positive color segment presents a non-periodic distribution; the backside viewing area presents a backside color spectrum matrix along the longitudinal axis, which is composed of at least two color segments, the color types of the backside color segments are all different from all color types of the positive color segments, the sequence of the length of each backside color segment presents a non-periodic distribution independent of the length sequence of the positive color segments; and, in the positive color spectrum matrix and / or the backside color spectrum matrix, a functional security material is uniformly and diffusely distributed within at least one designated color segment.

2. The positive and negative color different and segment different composite anti-counterfeit fiber according to claim 1, characterized in that, the non-circular cross-sectional profile is an equilateral triangle; the equilateral triangle cross-section physically divides the outer surface of the fiber into three continuous viewing faces, wherein any two adjacent viewing faces are collectively defined as the positive viewing area, and the remaining one viewing face is defined as the backside viewing area.

3. The positive and negative color different and segment different composite anti-counterfeit fiber according to claim 1 or 2, characterized in that, the fiber is composed of a thermoplastic polymer as the base material, the thermoplastic polymer is selected from polyethylene terephthalate (PET), polyvinyl alcohol (PVA), polypropylene (PP), or polyamide (PA); preferably, the thermoplastic polymer is polyethylene terephthalate (PET) with an intrinsic viscosity of 0.60 dL / g to 0.85 dL / g.

4. The positive and negative color different and section different composite anti-counterfeit fiber according to claim 1, characterized in that, the non-periodic distribution of the positive color segment length sequence is determined by a first non-periodic output sequence generated by a first deterministic chaotic dynamic system; the non-periodic distribution of the backside color segment length sequence is determined by a second non-periodic output sequence generated by a second deterministic chaotic dynamic system different from the first deterministic chaotic dynamic system.

5. The positive and negative color different and segment different composite anti-counterfeit fiber according to claim 4, characterized in that, both the first deterministic chaotic dynamic system and the second deterministic chaotic dynamic system use the Logistic Map algorithm, whose mathematical expression is x_{n+1} = r * x_n * (1 - x_n); wherein the chaotic parameter r and the initial value x0 of the first deterministic chaotic dynamic system are different from the chaotic parameter and the initial value of the second deterministic chaotic dynamic system, to ensure the mutual independence of the first non-periodic output sequence and the second non-periodic output sequence.

6. The positive and negative color different and section different composite anti-counterfeit fiber according to claim 1, characterized in that, the functional security material is selected from at least one of the following materials: an ultraviolet fluorescent material or an infrared excitation material capable of emitting characteristic fluorescence under excitation of specific wavelength light, an infrared absorption material having a characteristic absorption peak in a specific wavelength range, or a magnetic response material capable of generating a response under an alternating magnetic field.

7. The positive and negative color different and segment different composite anti-counterfeit fiber according to claim 6, characterized in that, The long-wave ultraviolet fluorescent material is an europium (Eu³⁺) organic complex capable of emitting narrow-band red fluorescence with a peak wavelength of 612 nm under the excitation of ultraviolet light at a wavelength of 365 nm; and the near-infrared absorbing material is a metal phthalocyanine derivative having a maximum absorption peak in the near-infrared spectral region, and the center wavelength of the maximum absorption peak is within a range of 880 nm ± 5 nm.

8. A method for preparing the front-back heterochromatic segmented composite anti-counterfeit fiber according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: S1: preparation of a multi-component master batch system, which comprises separately preparing a master polymer master batch for forming a fiber substrate, a plurality of colorant master batches for forming the front and back color segments, and one or more functional master batches for integrating the functional security materials; S2: generation and mapping of a chaotic control sequence, which comprises: constructing a first chaotic signal generator to generate a first non-periodic control sequence, and constructing a second chaotic signal generator independent of the first chaotic signal generator to generate a second non-periodic control sequence; and establishing a mapping relationship between the first and second non-periodic control sequences and the supply system of the plurality of colorant master batches to respectively and real-time non-periodically control the type selection and length formation of the front and back color segments; S3: space partitioning co-extrusion molding, which comprises: according to the control sequence generated in S2, on-line mixing the selected colorant master batch melt, the selectively added functional master batch melt, and the master polymer melt, and injecting the mixed front and back material streams into different regions of a composite spinning assembly having an internal partitioning flow channel to form a composite fiber nascent filament having the non-circular cross-sectional profile when leaving the spinneret hole; S4: post-processing and setting of the fiber, which comprises cooling and solidifying, multi-stage stretching and orientation, and heat setting of the composite fiber nascent filament to impart stable physical properties and dimensional accuracy to the fiber.

9. The method for preparing the positive and negative color different segment composite anti-counterfeit fiber according to claim 8, characterized in that, In the S3 space partitioning co-extrusion molding step, the composite spinning assembly used has a Y-shaped internal partitioning flow channel that physically divides the internal melt channel of the assembly into three independent sectors; wherein the material stream for forming the front color spectrum matrix is injected into two adjacent sectors, and the material stream for forming the back color spectrum matrix is injected into the remaining sector, thereby forming a composite fiber having an equilateral triangular cross-sectional profile after extrusion.

10. A security article characterized in that, The security article is security paper or a security thread; When the security article is security paper, the composite security fiber is cut into short fibers with a length of 3-5 mm and added to the pulp in a mass ratio of 0.5-2.0% of the dry weight of the pulp to form the security paper. When the security article is a security thread, the composite security fiber is implanted into a paper or polymeric substrate as a continuous filament, either in a windowed or fully embedded fashion.