Preparation method of ultrahigh polyethylene fiber melt spinning

Abstract

The invention discloses a preparation method of ultrahigh polyethylene fiber melt spinning. The ultrahigh polyethylene fiber melt spinning is prepared through the steps of raw material selection, threaded block assembly adjustment, mixing homogenization, spinning, sizing drafting and the like. The method has the advantages that the ultra-high molecular weight polyethylene powder is modified, the spinnability is improved, double-screw production equipment is modified, the shearing effect is greatly enhanced, color filaments of different colors can be produced at any time through control over feeding of double feeding ports, the dyeing color fastness is not lower than level 3, and the production efficiency is improved. The application range of the melt spinning ultra-high molecular weight polyethylene fiber is expanded. And in the production process, no solvent needs to be added, no waste water and waste liquid recovery pressure exists, the method is environmentally friendly, the minimum daily productivity reaches 1 t / day, and the problems that a conventional wet process is low in yield, large in recovery pressure and complex in production process are effectively solved.

Description

Technical Field

[0001] The invention relates to the field of polymer spinning, and in particular to a preparation method of ultra-high polyethylene fiber melt spinning. Background Art

[0002] Ultra-high polyethylene fiber melt spinning is to melt ultra-high molecular weight polyethylene (UHMWPE) at high temperature, extrude it through a spinneret to form primary fibers, and then stretch and heat treat it to obtain the final fiber product. UHMWPE fiber has extremely high strength and modulus. Its specific strength is more than ten times that of steel wire with the same cross-section, and its specific modulus is second only to special carbon fiber. It also has the advantages of low density and chemical corrosion resistance. With the rapid development of my country's ultra-high molecular weight polyethylene (UHMWPE) fiber industry and the continuous growth of the industry scale, UHMWPE fiber has been widely used in the military field (such as personal protection such as bulletproof vests and bulletproof helmets, armored protection such as tanks, ships, helicopters, etc.) and the industrial sector (marine cables, fishery farming, sports equipment, radar covers, cut-resistant fabrics, etc.) due to its excellent performance.

[0003] However, the production process of ultra-high molecular weight polyethylene fibers in the existing technology is mostly gel spinning. The gel spinning production process is complicated, there is a certain degree of environmental pollution, and it is often subject to recycling, extraction and production pressure. The cost remains high, and the development in the civilian field is slow. Summary of the invention

[0004] The technical problems to be solved by the present invention are how to avoid large solvent pollution in the production method of ultra-high molecular weight polyethylene fibers, how to avoid solvent recovery and extraction, and how to improve production efficiency. In view of the above technical problems to be solved, a preparation method for ultra-high molecular weight polyethylene fibers by melt spinning is now proposed.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing ultra-high polyethylene fiber melt spinning, wherein ultra-high polyethylene fiber melt spinning is prepared by the following steps:

[0006] Step 1: Raw material selection: select modified ultra-high molecular weight polyethylene powder, low particle size color powder and functional additives for standby use;

[0007] Step 2: Adjust the screw block assembly. Arrange the screw block assembly of the twin screw according to the type of raw materials. Use a wide pitch forward screw block in the feeding section, a narrow pitch meshing block in the melting section, and a reverse screw block in the exhaust section.

[0008] Step 3: mixing and homogenizing, adding the modified ultra-high molecular weight polyethylene powder and the low particle size color powder into the twin-screw extruder through two feeding ports, mixing and homogenizing to obtain a uniform fiber spinning solution;

[0009] Step 4: spinning, extruding the fiber spinning solution from the spinning piece through a metering pump to obtain primary jelly filaments;

[0010] Step five, shaping and stretching, the raw gel filaments are shaped by air cooling, and then stretched by hot rollers to obtain the finished modified ultra-high polyethylene fiber.

[0011] Furthermore, the molecular weight of the ultra-high molecular weight polyethylene powder in step one is in the range of 100,000 to 1,000,000.

[0012] Furthermore, the density of the modified ultra-high molecular weight polyethylene powder is 0.3 g / cm 3 -1.0g / cm 3 .

[0013] Furthermore, the particle size of the toner in step one is less than 10 um; the amount of toner added is 0%-6% of the total amount of powder added in the production batching process.

[0014] Furthermore, during the feeding process of step three, the weight of the powder is measured by a loss-in-weight scale.

[0015] Furthermore, the mixing temperature in the extruder in step three is set to 200-300°C.

[0016] Furthermore, the spinning temperature in step five is 220-280°C.

[0017] Furthermore, the functional additive is one or more of an antistatic agent, an anti-ultraviolet agent and a flow modifier.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The invention improves the spinnability by modifying the ultra-high molecular weight polyethylene powder, transforms the production twin-screw equipment, greatly enhances the shearing effect, and can produce colored yarns of different colors at any time through the control of feeding with double feeding ports, and the color fastness of dyeing is not less than level 3, expanding the application range of melt-spun ultra-high molecular weight polyethylene fibers. In addition, no solvent needs to be added during the production process, there is no wastewater and waste liquid recovery pressure, it is environmentally friendly, and the daily production capacity reaches a minimum of 1t / day, effectively solving the problems of low output, high recovery pressure, and complex production process of conventional wet process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the process of the present invention.

[0021] Figure 2 It is a schematic structural diagram of a twin-screw feeding port including a loss-in-weight scale in the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] See also Figure 1 As shown, this specific embodiment discloses a method for preparing ultra-high polyethylene fiber melt spinning, and ultra-high polyethylene fiber melt spinning is prepared by the following steps:

[0024] Step 1: Raw material selection: select modified ultra-high molecular weight polyethylene powder, low particle size color powder and functional additives for standby use;

[0025] The molecular weight of the ultra-high molecular weight polyethylene powder ranges from 100,000 to 1,000,000. The density of the modified ultra-high molecular weight polyethylene powder is 0.3g / cm 3 -1.0g / cm 3 .

[0026] As a further preferred embodiment, the particle size of the toner is less than 10um, and the amount of the toner added is 0%-6% of the total amount of powder added during the production and batching process. The color and amount of the toner are adjusted according to the needs of production and processing.

[0027] Step two, adjust the thread block assembly, combine and arrange the twin-screw thread block assembly according to the type of raw materials, use a wide-pitch forward thread block in the feeding section, a narrow-pitch meshing block in the melting section, and a reverse thread block in the exhaust section; more preferably, the staggered angles between the thread blocks can also be adjusted accordingly, for example, the angles between the thread blocks are set to 30°, 60°, 90°, etc., so as to ensure the shearing effect.

[0028] Step 3: Mixing and homogenizing: adding the modified ultra-high molecular weight polyethylene powder and the low particle size color powder to the twin-screw extruder through two feeding ports, mixing and homogenizing to obtain a uniform fiber spinning solution; wherein the mixing temperature is set between 200 and 300°C, and the specific temperature can be adjusted according to the selected powder. More preferably, the weight of the powder is weighed by a loss-in-weight scale during the feeding process.

[0029] More preferably, the functional additive is one or more of an antistatic agent, an anti-ultraviolet agent and a flow modifier.

[0030] Step 4: spinning, extruding the fiber spinning solution from the spinning piece through a metering pump to obtain primary jelly filaments;

[0031] Step five, shaping and stretching, the raw gel yarn is shaped by air cooling, and then stretched by hot rollers to obtain the modified ultra-high polyethylene fiber product, wherein the spinning temperature is 220-280°C.

[0032] The invention improves the spinnability by modifying the ultra-high molecular weight polyethylene powder, transforms the production twin-screw equipment, greatly enhances the shearing effect, and can produce colored yarns of different colors at any time through the control of feeding with double feeding ports, and the color fastness of dyeing is not less than level 3, expanding the application range of melt-spun ultra-high molecular weight polyethylene fibers. In addition, no solvent needs to be added during the production process, there is no wastewater and waste liquid recovery pressure, it is environmentally friendly, and the daily production capacity reaches a minimum of 1t / day, effectively solving the problems of low output, high recovery pressure, and complex production process of conventional wet process.

[0033] The above solution is explained in detail below in conjunction with more specific embodiments.

[0034] Example 1

[0035] In this embodiment, the ultra-high molecular weight polyethylene powder is first modified to obtain powder 1; wherein the molecular weight of the ultra-high molecular weight polyethylene powder ranges from 100,000 to 1,000,000 (in accordance with GB / T 32679-2016 standard), and the density of the modified ultra-high molecular weight polyethylene powder is 0.3 g / cm 3 -1.0g / cm 3, the powder density refers to the melt density; the modification method is one or more of physical coating, chemical coating, and high-energy surface modification, including but not limited to infrared, plasma irradiation, electron beam radiation, polymer, silane and other coupling agents or surfactants. Specifically, for example, a high-energy surface modification method is used for modification, such as plasma modification. Through plasma treatment, polar groups can be introduced on the surface of the polyethylene material, thereby improving its surface wettability and bonding properties. This method is environmentally friendly and efficient, and will not damage the material substrate. Another example is ultraviolet light irradiation grafting, which uses ultraviolet light radiation to initiate the grafting reaction of monomers on the surface of polyethylene materials, thereby introducing functional groups to improve the tribological properties, biocompatibility, antibacterial properties, etc. of the material. This method is simple to operate, but it requires the selection of appropriate light sources and monomers. Another example is electron beam irradiation grafting, which is similar to ultraviolet light irradiation grafting, but uses electron beams as radiation sources. The electron beam has higher energy, which can change the surface structure of the material at a deeper level and improve the mechanical properties of the material such as hardness and wear resistance. Gamma-ray irradiation grafting, using gamma rays as a radiation source, can also trigger the grafting reaction of monomers on the surface of polyethylene materials. This method is suitable for large-scale production, but attention should be paid to radiation safety and protective measures. There are also methods such as corona discharge modification, which can generate free radicals on the surface of polyethylene materials through corona discharge treatment, thereby initiating chemical reactions and improving the adhesion and printability of the materials. This method has simple equipment and low cost, but the effect may not be as significant as other high-energy beam treatment methods.

[0036] (2) Select appropriate color powder to obtain additive 1; wherein the color powder particle size is controlled to be below 10 μm and is easily dispersed; the color powder addition amount is 0%-6%, and the ratio refers to the mass ratio of the added color powder / (added color powder + powder 1) during the production batching process of the added color powder; preferably, in this specific embodiment, in order to improve the mixing efficiency, a flow agent can also be added to the powder. Specifically, in this embodiment, a lubricant-type flow modifier is used, such as stearic acid, zinc stearate, polyol ester (PETS), etc. Specifically, in this embodiment, 12% of the total weight ratio of zinc stearate is added.

[0037] (3) The twin-screw screw block components are re-arranged to enhance the shearing effect and accelerate the homogenization of the material; the combination arrangement of the twin-screw screw blocks means that in the actual processing process, the meshing blocks are often used in combination with other screw elements (such as forward screw blocks, reverse screw blocks, etc.) to achieve different processing effects. Specifically, in the present invention, a wide-pitch forward screw block may be used in the feeding section to improve the conveying capacity; a narrow-pitch meshing block may be used in the melting section to enhance the shearing effect; and a reverse screw block may be used in the exhaust section to form back pressure to help discharge moisture and low-molecular substances in the material.

[0038] (4) The twin-screw feeding port is modified to set a dual feeding port mode. The loss-in-weight scale 1 automatically feeds the powder 1, and the loss-in-weight scale 2 automatically feeds the additive 1. The structure of the twin-screw feeding port of the loss-in-weight scale is shown in the attached figure. Figure 2 ; 3 refers to the twin-screw extruder.

[0039] (5) The addition ratio of powder 1 to additive 1 is controlled by different feeding speeds of a loss-in-weight scale. The loss-in-weight scale greatly improves the efficiency of raw material proportioning, greatly improves production efficiency, and makes the processing process more continuous.

[0040] (6) The powder 1 and the auxiliary agent 1 are automatically fed according to the set process parameters and transported to a twin-screw extruder (200-300° C.) for continuous mixing and homogenization to obtain a uniform fiber spinning solution.

[0041] (7) The fiber spinning solution is squeezed out from the spinning element by a metering pump to obtain primary jelly fibers.

[0042] The nascent gel fibers are air-cooled and then drawn by hot rollers without extraction or recovery, and are directly drawn into the modified ultra-high polyethylene fiber products with the required fineness. The spinning temperature is 220-280°C. The color of the finished fiber is determined by the amount of additive 1 added and the color added.

[0043] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0044] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0045] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A method for preparing ultra-high polyethylene fiber by melt spinning, characterized in that: Ultra-high polyethylene fiber melt spinning is prepared by the following steps: Step 1: Raw material selection: select modified ultra-high molecular weight polyethylene powder, low particle size color powder and functional additives for standby use; Step 2: Adjust the screw block assembly. Arrange the screw block assembly of the twin screw according to the type of raw materials. Use a wide pitch forward screw block in the feeding section, a narrow pitch meshing block in the melting section, and a reverse screw block in the exhaust section. Step 3: mixing and homogenizing, adding the modified ultra-high molecular weight polyethylene powder and the low particle size color powder into the twin-screw extruder through two feeding ports, mixing and homogenizing to obtain a uniform fiber spinning solution; Step 4: spinning, extruding the fiber spinning solution from the spinning piece through a metering pump to obtain primary jelly filaments; Step five, shaping and stretching, the raw gel filaments are shaped by air cooling, and then stretched by hot rollers to obtain the finished modified ultra-high polyethylene fiber.

2. The method for preparing ultra-high polyethylene fiber by melt spinning according to claim 1, characterized in that: The molecular weight of the ultra-high molecular weight polyethylene powder in step 1 is in the range of 100,000 to 1,000,000.

3. The method for preparing ultra-high polyethylene fiber by melt spinning according to claim 1, characterized in that: The modified ultra-high molecular weight polyethylene powder has a density of 0.3 g / cm 3 -1.0g / cm 3 .

4. The method for preparing ultra-high polyethylene fiber by melt spinning according to claim 1, characterized in that: The particle size of the toner in step one is less than 10um; the amount of toner added is 0%-6% of the total amount of powder added in the production batching process.

5. The method for preparing ultra-high polyethylene fiber by melt spinning according to claim 1, characterized in that: During the feeding process of step 3, the weight of the powder is measured by a loss-in-weight scale.

6. The method for preparing ultra-high polyethylene fiber by melt spinning according to claim 1, characterized in that: The mixing temperature in the extruder in step 3 is set to 200-300°C.

7. The method for preparing ultra-high polyethylene fiber by melt spinning according to claim 1, characterized in that: The spinning temperature in step 5 is 220-280°C.

8. The method for preparing ultra-high polyethylene fiber by melt spinning according to claim 1, characterized in that: The functional additive is one or more of an antistatic agent, an anti-ultraviolet agent and a flow modifier.

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