A core-sheath composite fiber with optical camouflage properties, its preparation method and application

Abstract

This invention discloses a modified PA56 / PA56 core-sheath composite fiber with optical camouflage properties, its preparation method, and its application. First, PA56, color powder, and activated carbon functional additives are mixed evenly and then modified by twin-screw melt extrusion. Then, using the modified PA56 as the sheath structure and pure PA56 as the core structure, a modified PA56 / PA56 core-sheath composite fiber with optical camouflage properties is prepared. This fiber can be used in military camouflage, specifically with the following characteristics: the overall brightness of the product differs from that of green vegetation by ≤0.2; the visible light spectral reflectance differs from that of green vegetation by ≤0.1; and the near-infrared spectral reflectance differs from that of green vegetation by ≤0.2.

Description

Technical Field

[0001] This invention belongs to the field of optical camouflage material production technology, and relates to a core-sheath composite fiber with optical camouflage properties, its preparation method and application. Background Technology

[0002] In modern warfare, with the use of various high-tech reconnaissance methods, the absence of camouflage would render all military targets and operations completely "transparent," allowing the enemy to take preemptive countermeasures and even use precision-guided weapons to destroy targets. Camouflage plays a crucial role in modern warfare, impacting the security of military targets and the smooth execution of military operations. The nylon materials used by the military are mostly PA6 and PA66, whose raw materials largely rely on petrochemicals. Bio-based PA56 is polypentanediamine adipate, polymerized from adipic acid and pentanediamine. Pentanediamine can be converted from lysine through bioengineering, reducing dependence on petroleum and making it more environmentally friendly. Summary of the Invention

[0003] Currently, the commonly used camouflage method is achieved through coating finishing. There is a lot of research in this area and the technology is relatively mature. However, the disadvantage of this method is that the moisture absorption and breathability of the fabric decrease after coating, and the camouflage function is reduced after multiple washes. Therefore, in order to solve the above problems, this invention prepares a new type of camouflage fiber, which has the advantages of stable and long-lasting camouflage function, and excellent moisture absorption, breathability and water resistance.

[0004] To address the aforementioned technical problems, this application provides the following technical solution:

[0005] This invention provides a core-sheath composite fiber with optical camouflage properties, comprising a sheath and a core, wherein the core is prepared from PA56;

[0006] The skin layer is prepared by weight of the following components: 70-90 parts of PA56, 8-15 parts of green pigment and 2-7 parts of activated carbon.

[0007] The PA56 mentioned above, also known as Nylon 56 in Chinese and Polyamide 56 or Nylon 56 in English, was purchased from the market.

[0008] Preferably, the green pigment is selected from one or more of iron oxide green, chromium oxide green, and yellow-blue mixed green pigments.

[0009] Preferably, the activated carbon is one or both of coconut activated carbon and bamboo activated carbon.

[0010] Preferably, the coconut activated carbon and bamboo activated carbon are modified by a treatment solution. The specific modification method is as follows: the activated carbon and the treatment solution are shaken in a constant temperature water bath at 50-60°C for 2-5 hours, then filtered and washed with water until the pH is 6-8, and dried in an oven at 100°C for 3 hours; the treatment solution is an aqueous solution of HCl, H2SO4 or HNO3, and the concentration of the treatment solution is 10%-20% (mass fraction).

[0011] Furthermore, the mass ratio of activated carbon to treatment liquid is 1:5 to 15;

[0012] Preferably, the particle size of both the green pigment and the activated carbon is 2-60 micrometers.

[0013] Furthermore, the particle size of both the green pigment and activated carbon is 2-15 micrometers.

[0014] The present invention also provides a method for preparing the above-mentioned core-sheath composite fiber with optical camouflage properties, comprising the following steps:

[0015] S1: Prepare dried slices and functional additives separately;

[0016] The dried slices were obtained by vacuum drying 70-90 parts of PA56 at 95-105°C for 2-5 hours, by weight; the water content was controlled at 450-550 ppm during the vacuum drying.

[0017] The functional additive is made by grinding 8-15 parts of green pigment powder and 2-7 parts of activated carbon in a ball mill for 1-3 hours and then vacuum drying at 95-105℃ for 2-4 hours; the particle size of the grinding is controlled within 60 micrometers.

[0018] S2: The dried chips and functional additives are melt-extruded by screw extrusion, water-cooled, air-dried, pelletized, and then vacuum-dried again at 95-105℃ for 2-5 hours to obtain modified PA56 chips; the water content is controlled at 450-550ppm during the second vacuum drying.

[0019] S3: Using the modified PA56 chips obtained in step S2 as the sheath layer and the dried chips obtained in step S1 as the core layer, they are melted by a screw and then co-extruded, cooled by side blowing, stretched, and wound to obtain the sheath-core composite fiber with optical camouflage properties; the co-extrusion adopts a sheath-core structure spinneret.

[0020] Preferably, in step S2, the temperature of the screw melt extrusion is 220-290℃.

[0021] Preferably, in step S3, the screw melting temperature is 230-295℃.

[0022] Preferably, in step S3, the temperature of the side-blowing air cooling is 15-25℃.

[0023] Preferably, in step S3, the winding speed is 4000-4500 m / min.

[0024] The present invention also provides an application of the above-mentioned core-sheath composite fiber with optical camouflage properties in the manufacture of military camouflage items.

[0025] Specifically, the military camouflage items are clothing, hats, belts, or tents made by weaving optical camouflage fibers.

[0026] The technical solution of the present invention has the following advantages compared with the prior art:

[0027] The purpose of this invention is to provide a modified PA56 / PA56 core-sheath composite fiber with optical camouflage properties, its preparation method, and its applications. First, functional auxiliaries and PA56 are modified via twin-screw extrusion to obtain modified PA56. Then, using the modified PA56 as the sheath and pure PA56 as the core, a modified PA56 / PA56 core-sheath composite fiber with optical camouflage properties is prepared. The core-sheath structure solves the problem of auxiliaries affecting spinning performance. When applied to military camouflage, the prepared fiber not only exhibits stable and durable camouflage properties but also excellent moisture absorption, air permeability, and washability.

[0028] The optical camouflage fiber prepared using this invention has a comprehensive brightness difference of ≤0.2 compared to green vegetation; a visible light spectral reflectance difference of ≤0.1 compared to green vegetation; and a near-infrared spectral reflectance difference of ≤0.2 compared to green vegetation. Detailed Implementation

[0029] To make the technical solution of the present invention more apparent and understandable, the technical solution of the present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention.

[0030] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] Example A below illustrates a method for preparing a core-sheath composite fiber with optical camouflage properties. The specific steps are as follows:

[0032] The first step is the modification of PA56: PA56 slices are vacuum dried at 100℃ for 2-5 hours, with the water content controlled at 500ppm±50; iron oxide green is ground in a ball mill for 2 hours, with the particle size controlled within 60 micrometers, and then dried at 100℃ for 3 hours; activated carbon is modified by a treatment solution, specifically: the treatment solution is selected from aqueous solutions of HCl, H2SO4, or HNO3, with a concentration of 15% (mass fraction); the mass ratio (bath ratio) of activated carbon to treatment solution is 1:10; the mixture is shaken in a constant temperature water bath at 50-60℃ for 3 hours; the mixture is filtered and washed with water until the pH reaches 7, and then dried in an oven at 100℃ for 3 hours.

[0033] Then, PA56, green pigment, and modified activated carbon are mixed evenly in a certain proportion, melt-extruded at 220-290℃ using a twin-screw extruder, and then cooled with water, air-dried, and pelletized to obtain modified PA56 chips.

[0034] The next step is the PA56 core-sheath structure spinning process: First, pure PA56 chips and modified PA56 chips are vacuum dried at 100℃ for 2-5 hours, with the water content controlled at 500±50ppm; then, the dried pure PA56 is used as the core and the modified PA56 is used as the sheath, and the fibers are melted by a screw and extruded through a core-sheath structure spinneret at 230-295℃, and then cooled by side blowing, drawn, and wound to obtain PA56 fibers with a camouflage effect.

[0035] The specific parameters of the above-mentioned method for preparing nylon 56 optical camouflage material are as follows:

[0036] Example 1

[0037] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 90 parts PA56, 8 parts iron oxide green, 2 parts coconut activated carbon (10% HCl, bath ratio 1:5, shaking at 50℃ for 3h); twin-screw modification temperature: 220-270℃.

[0038] PA56 spinning parameters: 40 parts modified PA56 (skin), 60 parts pure PA56 (core), spinning temperature 230-275℃, side blowing 15℃, winding speed 4000m / min.

[0039] Example 2

[0040] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 80 parts PA56, 15 parts chromium oxide green, 5 parts coconut activated carbon (10% H2SO4, bath ratio 1:10, shaking at 50℃ for 3h); twin-screw modification temperature: 220-270℃.

[0041] PA56 spinning parameters: 40 parts modified PA56 (skin), 60 parts pure PA56 (core), spinning temperature 230-275℃, side blowing 15℃, winding speed 4000m / min.

[0042] Example 3

[0043] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 80 parts PA56, 15 parts green color powder mixed with yellow and blue, 5 parts bamboo activated carbon (10% H2SO4, bath ratio 1:10, shaking at 60℃ for 3h); twin-screw modification temperature: 220~270℃.

[0044] PA56 spinning parameters: 50 parts modified PA56 (skin), 50 parts pure PA56 (core), spinning temperature 230~285℃, side blowing 20℃, winding speed 4200m / min.

[0045] Example 4

[0046] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 73 parts PA56, 15 parts chromium oxide green, 7 parts bamboo activated carbon (10% HNO3, bath ratio 1:10, shaking at 50℃ for 3h); twin-screw modification temperature: 220~270℃.

[0047] PA56 spinning parameters: 60 parts modified PA56 (skin), 40 parts pure PA56 (core), spinning temperature 230~285℃, side blowing 20℃, winding speed 4200m / min.

[0048] Example 5

[0049] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 85 parts PA56, 13 parts iron oxide green, 2 parts bamboo activated carbon (10% HNO3, bath ratio 1:15, shaking at 50℃ for 3h); twin-screw modification temperature: 220~270℃.

[0050] PA56 spinning parameters: 50 parts modified PA56 (skin), 50 parts pure PA56 (core), spinning temperature 230~285℃, side blowing 20℃, winding speed 4200m / min.

[0051] Example 6

[0052] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 85 parts PA56, 13 parts iron oxide green, 2 parts coconut activated carbon (10% HNO3, bath ratio 1:10, shaking at 60℃ for 5h); twin-screw modification temperature: 220~270℃.

[0053] PA56 spinning parameters: 50 parts modified PA56 (skin), 50 parts pure PA56 (core), spinning temperature 230~290℃, side blowing 20℃, winding speed 4300m / min.

[0054] Example 7

[0055] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 85 parts PA56, 7 parts yellow pigment and 7 parts blue pigment mixed to form green pigment, 2 parts coconut activated carbon (15% H2SO4, bath ratio 1:10, shaking at 60℃ for 3h); twin-screw modification temperature: 220~280℃.

[0056] PA56 spinning parameters: 35 parts modified PA56 (skin), 65 parts pure PA56 (core), spinning temperature 230~290℃, side blowing 20℃, winding speed 4300m / min.

[0057] Example 8

[0058] Based on the above Example A, the specific parameters are as follows: PA56 modification parameters: 85 parts PA56, 13 parts iron oxide green, 2 parts bamboo activated carbon (20% HCl, bath ratio 1:5, shaking at 50℃ for 3h); twin-screw modification temperature: 220~280℃.

[0059] PA56 spinning parameters: 65 parts modified PA56 (skin), 35 parts pure PA56 (core), spinning temperature 230~290℃, side blowing 20℃, winding speed 4300m / min.

[0060] Comparative Example 1

[0061] Based on the above embodiment A, the difference is that both the skin and the core are pure PA56, without the addition of green pigment or activated carbon.

[0062] PA56 spinning parameters: 65 parts pure PA56 (skin), 35 parts pure PA56 (core), spinning temperature 230~290℃, side blowing 20℃, winding speed 4300m / min.

[0063] The data in Table 1 are obtained by measuring the fibers prepared in each example after they were woven into fabrics, with Comparative Example 1 being obtained from testing commercially available green nylon fabric:

[0064] Table 1. Camouflage Performance of Each Embodiment

[0065]

[0066] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. Use of a core-sheath composite fiber having optical camouflage properties in the manufacture of military camouflage articles, characterized in that, The core-sheath composite fiber with optical camouflage characteristics comprises a sheath layer and a core layer. S1: preparing dry slices and functional additives respectively; The dry slices are prepared by vacuum drying PA56 at 95-105 DEG C for 2-5 h, and the water content is controlled at 450-550 ppm during the vacuum drying. The functional additives are prepared by grinding green color powder and activated carbon in a ball mill for 1-3 h, and then vacuum drying at 95-105 DEG C for 2-4 h; the particle size of the grinding is controlled within 60 microns; the green color powder is selected from iron oxide green, chromium oxide green and yellow-blue mixed green color powder, and the yellow-blue ratio is (30%-70%):(70%-30%); the activated carbon is one or both of coconut activated carbon and bamboo activated carbon; the coconut activated carbon and bamboo activated carbon are modified by a treatment liquid, and the treatment liquid is an aqueous solution of HCl, H2SO4 or HNO3; the particle size of the green color powder and activated carbon is 2-60 microns; S2: screw melting extrusion of the dry slices and the functional additives, water cooling, air drying, granulation, and then secondary vacuum drying at 95-105 DEG C for 2-5 h to obtain modified PA56 slices; the water content is controlled at 450-550 ppm during the secondary vacuum drying. S3: using the modified PA56 slices obtained in step S2 as the sheath layer, and using the dry slices obtained in step S1 as the core layer, respectively melting by screw, co-extruding, side blowing air cooling, drawing, winding to obtain the core-sheath composite fiber with optical camouflage characteristics; the co-extrusion adopts a core-sheath structure spinneret.

2. Use of the core-sheath composite fiber having the optical camouflage property according to claim 1 in the production of a military camouflage article, characterized by, In step S2, the temperature of screw melting extrusion is 220-290 DEG C.

3. Use of the core-sheath composite fiber having the optical camouflage property according to claim 1 in the production of a military camouflage article, characterized by, In step S3, the temperature of screw melting is 230-295 DEG C.

4. Use of the core-sheath composite fiber having the optical camouflage property according to claim 1 in the production of a military camouflage article, characterized by, In step S3, the temperature of side blowing air cooling is 15-25 DEG C, and the winding speed is 4000-4500 m / min.

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