Scene-adaptive colored MPM non-woven fabric and production method and system thereof

Abstract

The invention provides a scene-adaptive colored MPM non-woven fabric and a production method and system thereof, and belongs to the technical field of new materials. According to the MPM non-woven fabric with flexibly designed colors and the efficient production mode of the MPM non-woven fabric, the rich color series can be prepared only through a small number of primary color raw materials, the supply chain and the production process are greatly simplified, and the economical efficiency is improved; the obtained product is uniform in color, stable, safe and non-toxic, the excellent fluffy feeling and liquid absorption performance of the material are kept, meanwhile, the product can be directly endowed with specific visual attributes and a scene recognition function through accurate color languages, and therefore the bottleneck of traditional non-woven fabric in homogenized market competition is broken through, and the market competitiveness of the non-woven fabric is improved. The key support is provided for entering high-end moms and babies, professional medical treatment, personalized sports, industrial wiping and other high-value-added fields.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, and in particular to a scene-adaptive colored MPM nonwoven fabric and its production method and system. Background Technology

[0002] MPM (Melt-Pulp-Melt) manufacturing is an innovative dry nonwoven technology. Its core lies in the online collaborative operation of two meltblown systems and one pulp fiber system: two streams of meltblown ultrafine fibers and one stream of pulp fibers are instantaneously mixed in the air during the molding process. Utilizing the self-adhesive properties of molten PP fibers, fiber composite and reinforcement are completed in one step, requiring no water or chemical adhesives throughout the entire process. Currently, the mainstream composite material is a combination of polypropylene (PP) and wood pulp.

[0003] The material produced using this process is MPM nonwoven fabric—a composite material that combines the environmentally friendly and washable properties of wood pulp with the soft and high-strength characteristics of meltblown microfiber. It is primarily used in the cleaning and personal care industry, such as in wet wipes, dry wipes, and makeup remover wipes. Its production process cleverly integrates meltblown technology and pulp fiber crushing technology: first, the natural wood pulp fiber raw material is fully dispersed into single fibers using a defiberizer to ensure its excellent liquid absorption and environmentally friendly properties; simultaneously, meltblown PP material is melted at high temperatures and then sprayed out as microfiber through a precision die. These fibers, thanks to their self-adhesive properties, are formed in one step in the airflow, tightly bonding with the fluffy wood pulp fiber layer. The resulting MPM nonwoven fabric not only possesses the unique microstructure and self-adhesive advantages of meltblown fibers but also the high liquid absorption characteristics of wood pulp fibers, exhibiting a unique fluffy and soft texture, with particularly outstanding water absorption performance.

[0004] However, as consumer demand for personalization and functionality continues to rise, the limitations of MPM nonwoven fabrics in color expression are becoming increasingly apparent. While the currently mainstream primary color (white) nonwoven fabric is highly practical, it struggles to meet the diverse color requirements of different sectors. In fact, color has become a crucial carrier of product function and emotional value. Through precise color positioning, nonwoven fabrics can not only enhance visual appeal but also establish deep connections with specific usage scenarios, thereby breaking through the current situation of homogeneous competition. For example, high-end maternal and infant products require soft macaron colors to convey a sense of security; medical protective equipment relies on calm blue-green tones to establish a professional image; and sports care products pursue highly saturated, vibrant colors to enhance the user experience. Summary of the Invention

[0005] The purpose of this invention is to provide a scene-adaptive colored MPM nonwoven fabric and its production method and system, which solves the problem that the current MPM nonwoven fabric has a single color and cannot meet the functional and emotional needs of different application scenarios through its own color.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for producing colored MPM nonwoven fabric, the method comprising the following steps: Using at least two independent meltblown extrusion systems, each system melts and spins polypropylene raw materials with different types or concentrations of color masterbatch to form at least two streams of meltblown ultrafine fibers of different colors. At the same time, the wood pulp board is defiberized to form a stream of wood pulp fibers; The at least two streams of meltblown microfiber of different colors and the single stream of wood pulp fiber are mixed and interwoven in three dimensions in the space above the forming screen. By utilizing the self-adhesive properties of meltblown polypropylene fibers, the mixed fiber web is thermally bonded and reinforced, resulting in a one-step molding process for colored MPM nonwoven fabric.

[0007] Preferably, one of the at least two meltblown extrusion systems is configured as a primary color generation unit, the fibers of which constitute a color base; and at least the other is configured as a hue correction unit, the fibers of which are used to fine-tune the hue of the color base.

[0008] Preferably, the color masterbatch is added to the polypropylene raw material at a ratio of 0.5-5%, and the wood pulp fiber accounts for 40-80% of the final nonwoven fabric by mass.

[0009] Preferably, by dynamically adjusting the mass percentage of the wood pulp fiber within the range of 40% to 80%, continuous control of the overall color brightness or saturation of the nonwoven fabric can be achieved.

[0010] Preferably, in the three-dimensional online mixing step, the degree of mixing of different fibers is controlled by independently adjusting at least one of the following parameters: the spray angle of each meltblown die head, the vertical distance from the fiber outlet to the forming screen, the meltblown fiber airflow velocity, and the wood pulp fiber airflow velocity. The spray angles of at least two meltblown dies are adjusted to deflect in opposite directions; The angles of the opposing deflections are each independently between 10° and 60°.

[0011] Preferably, the vertical distance from the fiber outlet to the formed mesh curtain is set to 150mm to 800mm.

[0012] The present invention also provides a colored MPM nonwoven fabric prepared by the above-described production method.

[0013] Preferably, the color of the nonwoven fabric is configured to indicate or adapt to the function or use scenario of the disposable hygiene product.

[0014] Preferably, the hygiene products include wipes, sanitary napkins, panty liners, diapers, medical dressings, or surgical gowns.

[0015] The present invention also provides a system for producing colored MPM nonwoven fabric, comprising: At least two independent meltblown extrusion units, each equipped with an independent masterbatch addition and metering module, melt extrusion module and precision spinning die; A wood pulp fiber processing device, comprising a wood pulp defiber and a wood pulp fiber conveying channel connected to the outlet of the defiber; A shared molding screen is arranged below the spinning die of the at least two meltblown extrusion units and below the outlet of the wood pulp fiber conveying channel; The system is configured as follows: Control the operation of the first meltblown extrusion device to spin and extrude a first fiber stream constituting a color base according to a first color masterbatch formula, the formula containing one or more color masterbatches and each color masterbatch having a first concentration; Simultaneously, the second meltblown extrusion device is controlled to operate, so that it spins and sputters a second fiber stream for hue fine-tuning the color base according to the second masterbatch formula, which differs from the first formula in the type of masterbatch and / or the concentration of at least one masterbatch. Simultaneously, the operation of the wood pulp fiber processing device is controlled to de-fiber the wood pulp board and convey a stream of wood pulp fibers. The first fiber stream, the second fiber stream, and the wood pulp fiber stream are interwoven and combined in three dimensions in the air before reaching the molded mesh curtain.

[0016] The beneficial effects of this invention are: This invention successfully provides a scene-adaptive colored MPM nonwoven fabric and its production method and system. It requires only a small amount of base color raw materials to formulate a rich color series, which greatly simplifies the supply chain and production process and improves economic efficiency. The resulting product has uniform, stable, safe and non-toxic colors. While maintaining the excellent fluffiness and liquid absorption performance of the material itself, it can directly endow the product with specific visual attributes and scene recognition functions through precise color language. This breaks through the bottleneck of traditional nonwoven fabrics in the homogeneous market competition and provides key support for its entry into high-value-added fields such as high-end maternal and infant products, professional medical products, personalized sports products and industrial wiping products. Attached Figure Description

[0017] Figure 1 This is a flowchart of the present invention. Figure 2 It is made of white MPM nonwoven fabric; Figure 3 Photograph 1 of the colored MPM nonwoven fabric produced according to the present invention; Figure 4 Photograph 2 of the color MPM nonwoven fabric produced according to the present invention. Detailed Implementation

[0018] The core of the production method described in this invention lies in an innovative online composite and coloring technology for multi-component fibers. This method overcomes the limitations of traditional nonwoven fabric dyeing processes, achieving integrated manufacturing of product color, structure, and performance by integrating color at the molding source.

[0019] Specifically, the method includes the following steps: First, the fiber stream is prepared. This invention uses at least two independent meltblown extrusion systems. Meltblown technology, as a mature technology for producing microfiber nonwoven fabrics, works by using high-speed hot air to stretch a fine stream of polymer melt extruded from a spinneret into ultrafine fibers, which are then collected onto a web-forming curtain under the action of airflow and randomly bonded together to form a fiber web. In this invention, we have creatively improved this conventional technology by applying it to the generation and control of color. Each meltblown extrusion system is independently controlled, and polypropylene raw materials with different types or concentrations of color masterbatches are melt-spun separately.

[0020] The polypropylene described herein is one of the most commonly used thermoplastic polymer raw materials in meltblown processes in this field. It has a moderate melting point, good fluidity, low cost, and excellent spinnability and chemical stability. The masterbatch is an aggregate made by uniformly loading a high proportion of pigments or dyes onto a resin carrier, and is widely used for coloring in the plastics and fiber processing industries. Its advantages include uniform coloring, bright colors, and ease of metering and automated production. By premixing different types (such as red, yellow, and blue primary colors) or different concentrations (i.e., addition ratios) of masterbatch with PP chips, and then feeding them separately into each meltblown system, after heating and melting, and screw shearing and mixing, at least two streams of meltblown ultrafine fibers of different colors can be sprayed out through a precision die. The preferred addition ratio of the masterbatch in the polypropylene raw material is 0.5% to 5%. This range is an optimal range verified by extensive practical experience. Too low a concentration may lead to unsaturated color development and a grayish color, while too high a concentration may affect the rheological properties of polypropylene and the stability of fiber forming, and increase costs.

[0021] While forming the colored meltblown fiber stream, a wood pulp fiber stream is prepared in parallel. This step involves defiberizing the dry-process wood pulp board. Wood pulp fiber, derived from natural wood, is an environmentally friendly and biodegradable cellulose fiber. In this invention, it is used as the base component of the composite material, primarily contributing excellent liquid absorption, bulkiness, and environmentally friendly washability. Using a specialized wood pulp defiberization device, the wood pulp board is instantly and mechanically separated into uniform, fluffy single wood pulp fibers, forming a stable white wood pulp fiber stream via an airflow conveying system. The wood pulp fiber accounts for 40% to 80% of the final nonwoven fabric by mass. This proportion is crucial because wood pulp fiber itself is white, acting as a natural "white diluent" and "brightness regulator." By dynamically adjusting its proportion, the overall color brightness and saturation of the final composite nonwoven fabric can be directly and continuously controlled without altering the masterbatch formulation. A higher wood pulp proportion results in a lighter color and higher brightness; conversely, a lower wood pulp proportion allows the meltblown fiber to dominate the color development, resulting in a brighter color and higher saturation.

[0022] The next crucial step is the three-dimensional online mixing process. At least two streams of meltblown microfiber of different colors and one stream of white wood pulp fiber, prepared earlier, are thoroughly and uniformly interwoven and mixed in a specific three-dimensional space above a shared forming mesh curtain as they fly towards it. This "aerial mixing" technology is the essence of the MPM process, enabling the random, three-dimensional network structure to be constructed from fibers of different components before they have been properly shaped.

[0023] To precisely control the mixing effect and the final color uniformity, this invention allows for independent adjustment of multiple physical parameters of the mixing process. For example, by independently adjusting the spray angle of each meltblown die, the coverage area and flight trajectory of the fiber stream can be changed. The adjustable range of the spray angle is typically between 0° and 60°. When the angle is set vertically downward (0°) or at a very small angle, the fiber stream is directly shot towards the screen with a minimal diffusion angle, which reduces its mixing with other fiber streams in the air; conversely, increasing the angle significantly deepens the mixing between fibers. Preferably, the spray angles of at least two meltblown dies are adjusted to deflect in opposite directions, i.e., one die deflects to the left by a certain angle, and the other die deflects to the right by a certain angle, and the angles of these opposite deflections can be independently selected within the range of 10° to 60°. This counter-spraying arrangement creates a better fiber mixing area, promoting the interweaving and interlacing of fibers of different colors.

[0024] Another key parameter is the vertical distance from the fiber outlet to the forming screen (often called the receiving distance). This distance is preferably adjustable between 150mm and 800mm. Adjusting this distance to a lower level (e.g., 150-200mm) will greatly limit the fiber's flight distance and time, causing it to settle rapidly onto the screen, thereby inhibiting deep interweaving of the fiber components in the vertical direction. Conversely, increasing this distance provides the fibers with longer flight and tumbling time, resulting in deeper fiber mixing and a more fluffy structure.

[0025] Furthermore, the airflow velocity of meltblown fibers and wood pulp fibers are also important control methods. Both velocities can be independently adjusted within a wide range (e.g., expressed as 0% to 100% of the equipment's maximum capacity). Airflow velocity directly determines the fiber's kinetic energy and its tumbling and diffusion in the air. Using higher wind speeds (e.g., adjusting to 80% or higher of the standard value) will increase the fiber's function and intensify its tumbling, thereby significantly increasing the mixing intensity among all fiber components (including PP fibers and wood pulp fibers of different colors), ultimately affecting the structure and macroscopic uniformity of the fiber web's color.

[0026] After mixing, the process moves to the reinforcement and molding stage. Utilizing the inherent hot-melt properties of the still semi-molten meltblown polypropylene fibers, which act as a natural hot-melt adhesive, they rapidly bond with the wood pulp fibers upon contact, simultaneously achieving inter-fiber bonding. This process requires no external chemical adhesives or water; it's a purely physical thermal bonding mechanism, ensuring the product's environmental friendliness and purity. Finally, through this one-step molding process, the fibers are collected on a molding screen and subsequently cooled, moderately compacted, and then wound into a tube to produce a uniformly colored and structurally robust colored MPM nonwoven fabric.

[0027] In a preferred embodiment, the at least two meltblown extrusion systems are assigned specific functional roles. One system is configured as a primary color generation unit, whose spun fibers form the base or tone of the product color; while at least the other system is configured as a hue correction unit, whose spun fibers are used to fine-tune the primary color, for example, by adding trace amounts of complementary colors to neutralize certain hues in the primary color, or by adding darker / lighter shades of the same color family to increase the color's depth and saturation. This collaborative division of labor greatly enhances the precision and flexibility of color design.

[0028] The present invention also provides a colored MPM nonwoven fabric prepared by any of the above-described production methods.

[0029] This nonwoven fabric is a composite material made from polypropylene microfibers of at least two colors and white wood pulp fibers through three-dimensional online mixing and thermal bonding in a one-step molding process. Because its color is intrinsically formed during the production process, rather than through subsequent dyeing, its color is uniform and stable, avoiding problems such as fading and chemical residues that may occur with traditional dyeing. Based on this characteristic, the color of the nonwoven fabric can be strategically configured to indicate or adapt to the function or usage scenario of the final product it is made from. This is an important application attribute of the product of this invention. For example, in the field of disposable hygiene products, specific colors can convey specific visual information and emotional associations. These hygiene products cover a wide range of categories, including but not limited to wipes (such as wet wipes and dry wipes), sanitary napkins, panty liners, diapers, medical dressings, or surgical gowns. Precise color positioning can enhance product market recognition and user experience. In one embodiment of this invention, light-colored nonwoven fabrics are used to prepare products for scenarios requiring a sense of cleanliness; dark-colored nonwoven fabrics are used to prepare products for scenarios requiring the concealment of stains or the expression of professionalism and stability.

[0030] The present invention also provides a dedicated system for producing colored MPM nonwoven fabrics.

[0031] This system forms the hardware foundation for implementing the above methods. It includes: At least two independent meltblown extrusion units. Each unit is a complete functional unit, typically including: an independent masterbatch addition and metering module (for precise control of the masterbatch ratio and delivery), a melt extrusion module (mainly including a screw extruder, heating system, melt pump, etc., for melting and mixing PP and masterbatch and delivering them stably), and a precision spinning die (with numerous micron-sized spinnerets, which is a key component for fiber forming).

[0032] A wood pulp fiber processing unit. The core of this unit is a wood pulp defiber machine, which uses mechanical force to break down and comb dense wood pulp boards into loose, single-fiber structures. Connected to the outlet of the defiber machine is a wood pulp fiber conveying channel, which typically uses airflow to smoothly and evenly transport the defibered wood pulp fibers to the mixing area.

[0033] A shared forming mesh curtain. Typically a porous, endless rotating belt, positioned below all meltblown dies and the outlet of the wood pulp fiber conveying channels, to receive the mixed fibers and form the initial fiber web while allowing air to pass through.

[0034] The innovative configuration of this system lies in its control logic. The system is integrated and controlled, enabling it to coordinately: The first meltblown extrusion device is controlled to spin fibers according to a first masterbatch formulation (which contains one or more masterbatches, each masterbatch having a specific first concentration), and to extrude a first fiber stream that constitutes the color base.

[0035] Simultaneously, the operation of the second meltblown extruder is controlled to spin fibers according to the second masterbatch formulation. Crucially, this second formulation differs from the first formulation in the type and / or concentration of at least one masterbatch, thereby extruding a second fiber stream for hue fine-tuning of the color base.

[0036] At the same time, the control system also starts the wood pulp fiber processing device to de-fiber the wood pulp board and deliver a stream of wood pulp fibers.

[0037] Ultimately, by setting the equipment layout and process parameters, the first fiber flow, the second fiber flow, and the wood pulp fiber flow are ensured to undergo full three-dimensional interweaving and compounding in the air before reaching the forming mesh curtain, thereby producing color-designable MPM nonwoven fabric in one step.

[0038] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention. A flowchart of the present invention is shown in the figure.

[0039] Example 1 Step 1: Raw material preparation and pretreatment Premixing PP with color masterbatch: The first premix: Polypropylene chips are physically premixed with 4.5% blue masterbatch and 1.5% yellow masterbatch in the batching system to form a homogeneous mixture.

[0040] The second premix: Polypropylene chips are physically premixed with 4.8% blue masterbatch and 0.3% red masterbatch in the batching system to form a homogeneous mixture.

[0041] Wood pulp board preparation: The wood pulp rolls were placed in a constant temperature and humidity environment of 23°C and 50% for equilibration treatment for 60 hours to ensure that the moisture content of the rolls reached a uniform 8%.

[0042] An active unwinding device, in conjunction with a tension control system, reduces the tension of the roll from 140 N / m to 25 N / m, thus achieving physical relaxation.

[0043] Step 2: Melt coloring, fiber defiberization and online mixing Melt extrusion and coloring: The first batch of premixed material was fed into the meltblown extrusion unit 1. The system was set to a melt temperature of 220℃, a melt pressure of 4.5MPa, and a screw speed of 40 rpm. The ultrafine cyan fiber stream was ejected through the die (spinneret orifice diameter 0.3 mm), with the fiber diameter controlled at 2 μm.

[0044] The second premixed material was fed into the meltblown extrusion unit 2. The system was set to a melt temperature of 225℃, a melt pressure of 4.8MPa, and a screw speed of 42 rpm. Ultrafine, dark blue tinted fiber streams were ejected through the die head, with a fiber diameter controlled at 2.2 μm.

[0045] Immediate defiberization of wood pulp: The pretreated wood pulp board enters the wood pulp defiberization device, where it is instantly separated into uniform white wood pulp fibers with a diameter controlled at 20 μm and an average fiber length of 1.8 mm. These fibers are then conveyed to the forming area via airflow. The wood pulp fibers account for 40% of the final nonwoven fabric by mass.

[0046] Three streams online mixed: The melting temperature adopts a gradient heating mode: 170℃ in the feeding section, 195℃ in the compression section, 220℃ in the metering section, and 230℃ in the die head. The hot air pressure is 0.35 MPa and the temperature is 245℃.

[0047] Die head A (meltblowing device 1) sprays 30° to the right of the forming screen; die head B (meltblowing device 2) sprays 30° to the left of the forming screen.

[0048] The receiving distance (from the die head to the forming screen) is set to 500 mm. The airflow velocity of both meltblown fiber and wood pulp fiber is set to 70% of the standard value.

[0049] The web-forming speed is set to 15 m / min. This allows the two meltblown fiber streams and one wood pulp fiber stream to undergo thorough and uniform three-dimensional interweaving and mixing in the air as they fly toward the web-forming curtain.

[0050] Step 3: Thermal bonding molding and winding Hot melt self-adhesive reinforcement: PP fibers in a semi-molten state act as a hot melt adhesive, quickly bonding the wood pulp fibers together upon contact to form a strong, integrated fiber web.

[0051] Web Formation and Winding: The mixed fiber web is collected on a forming screen, cooled, compacted, and then wound into a tube to produce a uniformly colored green MPM nonwoven fabric. (See photo.) Figure 3 As shown.

[0052] Example 2 Step 1: Raw material preparation and pretreatment Premixing PP with color masterbatch: The first premix: Polypropylene chips are physically premixed with 5.0% blue masterbatch and 0.8% red masterbatch in the batching system to form a homogeneous mixture.

[0053] The second premix: Polypropylene chips are physically premixed with 4.5% blue masterbatch and 0.2% yellow masterbatch in the batching system to form a homogeneous mixture.

[0054] Wood pulp board preparation: The wood pulp rolls were placed in a constant temperature and humidity environment of 24℃ and 52% for equilibration treatment for 55 hours to ensure that the moisture content of the rolls reached a uniform 7.5%.

[0055] An active unwinding device, in conjunction with a tension control system, reduces the tension of the roll material from 130 N / m to 28 N / m, thus achieving physical relaxation.

[0056] Step 2: Melt coloring, fiber defiberization and online mixing Melt extrusion and coloring: The first batch of premixed material was fed into the meltblown extrusion unit 1. The system was set to a melt temperature of 215℃, a melt pressure of 4.0MPa, and a screw speed of 38 rpm. Ultrafine blue fiber streams were ejected through the die (spinneret orifice diameter 0.25 mm), with the fiber diameter controlled at 1.8 μm.

[0057] The second premixed material was fed into the meltblown extrusion unit 2. The system was set to a melt temperature of 218℃, a melt pressure of 4.2MPa, and a screw speed of 35 rpm. Ultrafine blue-toned fiber streams were ejected through the die head, with the fiber diameter controlled at 1.9 μm.

[0058] Immediate defiberization of wood pulp: The pretreated wood pulp board enters the wood pulp defiberization device, where it is instantly separated into uniform white wood pulp fibers with a diameter controlled at 22 μm and an average fiber length of 2.0 mm. The fibers are then conveyed to the forming area via airflow. The wood pulp fibers account for 60% of the final nonwoven fabric by mass.

[0059] Three streams online mixed: The melting temperature adopts a gradient heating mode: 165℃ in the feeding section, 185℃ in the compression section, 215℃ in the metering section, and 235℃ in the die head. The hot air pressure is 0.3 MPa and the temperature is 238℃.

[0060] Die head A (meltblowing device 1) sprays 20° to the right of the forming screen; die head B (meltblowing device 2) sprays 20° to the left of the forming screen.

[0061] The receiving distance (from the die head to the forming screen) is set to 600 mm. The airflow velocity of both meltblown fiber and wood pulp fiber is set to 75% of the standard value.

[0062] The web-forming speed is set to 18 m / min. As the two meltblown fiber streams and one wood pulp fiber stream fly toward the web-forming curtain, they undergo thorough and uniform three-dimensional interweaving and mixing in the air. The semi-molten PP fiber acts as a hot-melt adhesive, rapidly bonding the wood pulp fiber together upon contact to form a strong, integrated fiber web.

[0063] Web Formation and Winding: The mixed fiber web is collected on a forming screen, cooled, compacted, and then wound into a tube to produce a uniformly colored blue MPM nonwoven fabric. (See photo.) Figure 4 As shown.

[0064] Example 3 Step 1: Raw material preparation and pretreatment Premixing PP with color masterbatch: The first premix: Polypropylene chips are physically premixed with 3.0% yellow masterbatch and 1.0% red masterbatch in the batching system to form a homogeneous mixture.

[0065] The second premix: Polypropylene chips are physically premixed with 2.5% yellow masterbatch and 0.5% red masterbatch in the batching system to form a homogeneous mixture.

[0066] Wood pulp board preparation: The wood pulp rolls were placed in a constant temperature and humidity environment of 22℃ and 48% for equilibration treatment for 65 hours to ensure that the moisture content of the rolls reached a uniform 8.5%.

[0067] An active unwinding device, in conjunction with a tension control system, reduces the tension of the roll material from 145 N / m to 22 N / m, thus achieving physical relaxation.

[0068] Step 2: Melt coloring, fiber defiberization and online mixing Melt extrusion and coloring: The first batch of premixed material was fed into the meltblown extrusion unit 1. The system was set to a melt temperature of 205℃, a melt pressure of 3.5MPa, and a screw speed of 45 rpm. Ultrafine orange-toned base fiber streams were ejected through the die (spinneret orifice diameter 0.35 mm), with the fiber diameter controlled at 3.5 μm.

[0069] The second premixed material was fed into the meltblown extrusion unit 2. The system was set to a melt temperature of 210℃, a melt pressure of 3.8MPa, and a screw speed of 48 rpm. Ultrafine light orange colored fiber streams were ejected through the die head, with the fiber diameter controlled at 3.8 μm.

[0070] Immediate defiberization of wood pulp: The pretreated wood pulp board enters the wood pulp defiberization device, where it is instantly separated into uniform white wood pulp fibers with a diameter controlled at 18 μm and an average fiber length of 1.5 mm. These fibers are then conveyed to the forming area via airflow. The wood pulp fibers account for 70% of the final nonwoven fabric by mass.

[0071] Three streams online mixed: The melting temperature adopts a gradient heating mode: 175℃ in the feeding section, 200℃ in the compression section, 225℃ in the metering section, and 240℃ in the die head. The hot air pressure is 0.4 MPa and the temperature is 250℃.

[0072] Die head A (meltblowing device 1) sprays 15° to the right of the forming screen; die head B (meltblowing device 2) sprays 15° to the left of the forming screen.

[0073] The receiving distance (from the die head to the forming screen) is set to 400 mm. The airflow velocity of both meltblown fiber and wood pulp fiber is set to 65% of the standard value.

[0074] The web-forming speed is set to 12 m / min. As the two meltblown fiber streams and one wood pulp fiber stream fly toward the web-forming curtain, they undergo thorough and uniform three-dimensional interweaving and mixing in the air. The semi-molten PP fiber acts as a hot-melt adhesive, rapidly bonding the wood pulp fiber together upon contact to form a strong, integrated fiber web.

[0075] Web Formation and Rolling: The mixed fiber web is collected on a forming screen, cooled, compacted, and then rolled into a tube to produce a uniformly colored light orange MPM nonwoven fabric. This material has a soft and warm tone, making it suitable for high-end maternal and infant care products, conveying a sense of safety and comfort.

[0076] Example 4 Step 1: Raw material preparation and pretreatment Premixing PP with color masterbatch: The first premix: Polypropylene chips are physically premixed with 2.0% blue masterbatch and 1.5% red masterbatch in the batching system to form a homogeneous mixture.

[0077] The second premix: Polypropylene chips are physically premixed with 1.5% blue masterbatch and 1.0% red masterbatch in the batching system to form a homogeneous mixture.

[0078] Wood pulp board preparation: The wood pulp rolls were placed in a constant temperature and humidity environment of 25°C and 53% for equilibration treatment for 50 hours to ensure that the moisture content of the rolls reached a uniform 7.2%.

[0079] An active unwinding device, in conjunction with a tension control system, reduces the tension of the roll from 125 N / m to 30 N / m, thus achieving physical relaxation.

[0080] Step 2: Melt coloring, fiber defiberization and online mixing Melt extrusion and coloring: The first batch of premixed material was fed into the meltblown extrusion unit 1. The system was set to a melt temperature of 235℃, a melt pressure of 5.5MPa, and a screw speed of 50 rpm. Ultrafine purple base fiber streams were ejected through the die (spinneret orifice diameter 0.28 mm), with the fiber diameter controlled at 2.5 μm.

[0081] The second premixed material was fed into the meltblown extrusion unit 2. The system was set to a melt temperature of 240℃, a melt pressure of 5.8MPa, and a screw speed of 55 rpm. Ultrafine light purple colored fiber streams were ejected through the die head, with a fiber diameter controlled at 2.7 μm.

[0082] Immediate defiberization of wood pulp: The pretreated wood pulp board enters the wood pulp defiberization device, where it is instantly separated into uniform white wood pulp fibers with a diameter controlled at 25 μm and an average fiber length of 2.2 mm. These fibers are then conveyed to the forming area via airflow. The wood pulp fibers account for 75% of the mass of the final nonwoven fabric.

[0083] Three streams online mixed: The melting temperature adopts a gradient heating mode: 160℃ in the feeding section, 190℃ in the compression section, 212℃ in the metering section, and 228℃ in the die head. The hot air pressure is 0.45 MPa and the temperature is 255℃.

[0084] Die head A (meltblowing device 1) sprays 10° to the right of the forming screen; die head B (meltblowing device 2) sprays 10° to the left of the forming screen.

[0085] The receiving distance (from the die head to the forming screen) is set to 700 mm. The airflow velocity of both meltblown fiber and wood pulp fiber is set to 80% of the standard value.

[0086] The web-forming speed is set to 25 m / min. As the two meltblown fiber streams and one wood pulp fiber stream fly toward the web-forming curtain, they undergo thorough and uniform three-dimensional interweaving and mixing in the air. The semi-molten PP fiber acts as a hot-melt adhesive, rapidly bonding the wood pulp fiber together upon contact to form a strong, integrated fiber web.

[0087] Web Formation and Rolling: The mixed fiber web is collected on a forming screen, cooled, compacted, and then rolled into a tube to produce a uniformly colored light purple MPM nonwoven fabric. This material has an elegant color and can be used in personal care or luxury cosmetics fields to enhance the visual appeal of products.

[0088] White MPM nonwoven fabric (as shown in the photo) Figure 2The green MPM nonwoven fabric and blue MPM nonwoven fabric prepared by this invention were subjected to performance testing, and the results are shown in Table 1 below: Table 1 Performance Test Results

[0089] As can be seen from the above embodiments, the present invention provides a colored MPM nonwoven fabric with excellent comprehensive performance. Experimental results show that the green and blue MPM nonwoven fabrics prepared by the described process are comparable to the white MPM nonwoven fabric of the same basis weight in key performance indicators such as basis weight, thickness, pH, and liquid absorption. At the same time, their tensile strength and elongation at break in both the longitudinal and transverse directions are well maintained. This confirms that the coloring process of the present invention, while achieving material color diversification, does not adversely affect its inherent physical properties, safety in use, and core functions.

[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing colored MPM nonwoven fabric, characterized in that, The method includes the following steps: Using at least two independent meltblown extrusion systems, each system melts and spins polypropylene raw materials with different types or concentrations of color masterbatch to form at least two streams of meltblown ultrafine fibers of different colors. At the same time, the wood pulp board is defiberized to form a stream of wood pulp fibers; The at least two streams of meltblown microfiber of different colors and the single stream of wood pulp fiber are mixed and interwoven in three dimensions in the space above the forming screen. By utilizing the self-adhesive properties of meltblown polypropylene fibers, the mixed fiber web is thermally bonded and reinforced, resulting in a one-step molding process for colored MPM nonwoven fabric.

2. The production method according to claim 1, characterized in that, One of the at least two meltblown extrusion systems is configured as a primary color generation unit, whose spun fibers constitute a color base; at least the other is configured as a hue correction unit, whose spun fibers are used to fine-tune the hue of the color base.

3. The production method according to claim 1, characterized in that, The color masterbatch is added to the polypropylene raw material at a ratio of 0.5-5%, and the wood pulp fiber accounts for 40-80% of the final nonwoven fabric by mass.

4. The production method according to claim 1, characterized in that, By dynamically adjusting the mass ratio of the wood pulp fiber within the range of 40% to 80%, continuous control of the overall color brightness or saturation of the nonwoven fabric can be achieved.

5. The production method according to claim 1, characterized in that, In the three-dimensional online mixing step, the degree of mixing of different fibers is controlled by independently adjusting at least one of the following parameters: the spray angle of each meltblown die head, the vertical distance from the fiber outlet to the forming screen, the meltblown fiber airflow velocity, and the wood pulp fiber airflow velocity. The spray angles of at least two meltblown dies are adjusted to deflect in opposite directions; The angles of the opposing deflections are each independently between 10° and 60°.

6. The production method according to claim 5, characterized in that, The vertical distance from the fiber outlet to the formed mesh curtain is set to 150mm to 800mm.

7. Colored MPM nonwoven fabric prepared by the production method according to any one of claims 1 to 6.

8. The application of the colored MPM nonwoven fabric according to claim 7 in the preparation of hygiene products, characterized in that, The color of the nonwoven fabric is configured to indicate or adapt to the function or use case of the disposable hygiene product.

9. The application according to claim 8, characterized in that, The hygiene products include wipes, sanitary napkins, panty liners, diapers, medical dressings, or surgical gowns.

10. A system for producing colored MPM nonwoven fabric, characterized in that, include: At least two independent meltblown extrusion units, each equipped with an independent masterbatch addition and metering module, melt extrusion module and precision spinning die; A wood pulp fiber processing device, comprising a wood pulp defiber and a wood pulp fiber conveying channel connected to the outlet of the defiber; A shared molding screen is arranged below the spinning die of the at least two meltblown extrusion units and below the outlet of the wood pulp fiber conveying channel; The system is configured as follows: Control the operation of the first meltblown extrusion device to spin and extrude a first fiber stream constituting a color base according to a first color masterbatch formula, the formula containing one or more color masterbatches and each color masterbatch having a first concentration; Simultaneously, the second meltblown extrusion device is controlled to operate, so that it spins and sputters a second fiber stream for hue fine-tuning the color base according to the second masterbatch formula, which differs from the first formula in the type of masterbatch and / or the concentration of at least one masterbatch. Simultaneously, the operation of the wood pulp fiber processing device is controlled to de-fiber the wood pulp board and convey a stream of wood pulp fibers. The first fiber stream, the second fiber stream, and the wood pulp fiber stream are interwoven and combined in three dimensions in the air before reaching the molded mesh curtain.

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