A kind of nylon master batch for twin-screw cleaning and its preparation method

Abstract

The application discloses a kind of nylon master batch for twin-screw cleaning and a preparation method thereof, belong to high polymer material technical field, carbonate, temperature regulator, PA6 chip are mixed to prepare, the nylon master batch prepared can be through carbonate in twin-screw system foaming pressurization to reach the effect of cleaning screw, the cleaning master batch disclosed in the application can reach 200 DEG C or more, more suitable for nylon high-temperature extrusion process;Carbonate in master batch decomposes to generate CO2 under high temperature, through foaming pressurization, with the synergistic effect of melt coating and gas scouring, the impurities in twin-screw system are brought out, to achieve the effect of cleaning twin-screw, the cleaning process is non-toxic and harmless, reduces the risk of mechanical damage and the consumption of PA6 matrix in large quantities, provides a green, sustainable new way for PA6 processing equipment cleaning.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a nylon masterbatch for twin-screw cleaning and its preparation method. Background Technology

[0002] Currently, there are two main technical routes for cleaning twin-screw extruders: resin displacement cleaning and mechanical disassembly cleaning, but both face application limitations. Resin displacement cleaning typically uses general-purpose resins such as polypropylene (PP) as the cleaning material, gradually displacing residues from the system through a passing-through process. However, ordinary resins are not designed for cleaning; their cleaning power is limited, and they often struggle to completely remove stubborn, carbonized residues. After PP cleaning, a large amount of PA6 matrix material still needs to be added, and the PP material in the system is carried out again through the machine to avoid cross-contamination. This process not only results in significant loss of matrix resin but also significantly prolongs equipment downtime. Industry practice shows that if ordinary resin cleaning is used, the cleaning time for materials prone to carbon buildup, such as nylon, can be as long as 3-4 hours, and the conversion time is highly uncertain.

[0003] Mechanical disassembly and cleaning involves manually removing the screw and physically cleaning the screw components and die head using methods such as high-temperature calcination or cleaning with organic solvents. Frequent disassembly and assembly leads to a decrease in the fit precision between the screw and the barrel, causing irreversible mechanical wear and shortening the equipment's lifespan. The entire process is time-consuming and labor-intensive. For production scenarios such as masterbatch manufacturing, where the screw needs to be disassembled multiple times per week, this loss of efficiency and labor costs represent an extremely heavy burden.

[0004] In addition to the two cleaning techniques mentioned above, cleaning methods involving the addition of cleaning materials have also been proposed. For example, Chinese patent CN109608726A discloses "A Machine Washing Masterbatch for Screw Extruders and Its Preparation Method," which specifically discloses a machine washing masterbatch for screw extruders composed of polyethylene, antioxidants, lubricants, propanol, calcium bicarbonate, and inorganic fillers. Calcium bicarbonate in this component decomposes under heat and pressure to produce carbon dioxide gas, which carries away internal odors during extrusion. Simultaneously, calcium bicarbonate releases some water when releasing carbon dioxide, which, through the water-miscible propanol, cleans the residual organic resin inside the screw, improving the screw's cleaning ability. However, existing cleaning materials often use organic polymer bases and have complex compositions, requiring further removal of residual impurities from the cleaning masterbatch after cleaning. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a nylon masterbatch for twin-screw cleaning and its preparation method. The nylon masterbatch for twin-screw cleaning is prepared by mixing carbonate, temperature regulator and PA6. The cleaning nylon masterbatch prepared by this invention can achieve the effect of cleaning the screw through foaming and pressurization of carbonate in the twin-screw system, and no new impurities are generated after cleaning.

[0006] To achieve the purpose of the invention, the following technical solution is provided: This invention discloses a nylon masterbatch for twin-screw cleaning, comprising the following components by mass percentage: 1-10% carbonate, 0.3-3% temperature regulator, and 87-98.7% PA6 chips.

[0007] Furthermore, the temperature regulator is a compound of acetate and stearic acid.

[0008] Furthermore, the carbonate is basic zinc carbonate and / or zinc carbonate.

[0009] Furthermore, the acetate is zinc acetate.

[0010] This invention also discloses a method for preparing nylon masterbatch for twin-screw extruder cleaning. Carbonate and temperature regulator are mixed evenly and added to the side feed hopper, PA6 chips are added to the main feed hopper, and the mixture is melt-blended and extruded and granulated by a twin-screw extruder to obtain clean nylon masterbatch. The preparation process is carried out at 210°C.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention discloses a nylon masterbatch for cleaning twin-screw extruders. The carbonates in the masterbatch decompose at high temperatures to produce CO2. Through foaming and pressurization, impurities in the twin-screw system are carried out by the synergistic effect of melt coating and gas flushing, achieving the effect of cleaning the twin-screw extruder, especially with basic zinc carbonate. The cleaning masterbatch disclosed in this invention has a thermal decomposition temperature of over 200°C, making it more suitable for high-temperature extrusion processes of nylon.

[0012] 2. In this invention, adding a temperature regulator to the masterbatch can reduce the activation energy of carbonates and accelerate their decomposition. For example, adding zinc acetate weakens the bond energy of the CO bond, reducing the activation energy required for the decomposition of basic zinc carbonate, thereby lowering the thermal decomposition temperature. Furthermore, adding stearic acid improves the dispersibility of basic zinc carbonate, reduces particle agglomeration, and ensures sufficient contact between zinc acetate and basic zinc carbonate particles, thus improving catalytic efficiency. By adjusting the ratio of zinc acetate to stearic acid, the thermal decomposition temperature range of basic zinc carbonate can be controlled to adapt to different cleaning scenarios for equipment using nylon as a base material.

[0013] 3. The products (such as zinc oxide and zinc stearate) after the decomposition of the nylon masterbatch prepared by this invention can be discharged with subsequent normal production materials, significantly reducing the frequency of screw disassembly and reducing equipment wear. Simultaneously, the amount of substrate discharged during the cleaning process can be reduced by 40-50% (compared to the cleaning method using PP material through a machine), achieving efficient and low-loss online cleaning. The cleaning process is non-toxic and harmless, reducing the risk of mechanical damage and the large consumption of PA6 substrate, providing a green and sustainable new approach for cleaning PA6 processing equipment. Detailed Implementation

[0014] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0015] Unless otherwise specified, all raw materials used in the following examples were purchased commercially.

[0016] Unless otherwise specified, the methods used in the following embodiments are conventional operating methods in the art.

[0017] Example 1 This embodiment provides a nylon masterbatch for twin-screw cleaning, comprising the following components by weight percentage: 10% basic zinc carbonate, 2% zinc acetate, 1% stearic acid, and 87% PA6 chips.

[0018] In this embodiment, the nylon masterbatch is prepared by mixing basic zinc carbonate, zinc acetate and stearic acid and adding them to the side feed hopper, adding PA6 chips to the main feed hopper, and then extruding and granulating the mixture after melt blending in a twin-screw extruder at a process temperature of 210°C.

[0019] Example 2 This embodiment provides a nylon masterbatch suitable for twin-screw cleaning, comprising the following components by weight percentage: 5% basic zinc carbonate, 1% zinc acetate, 0.5% stearic acid, and 93.5% PA6 chips.

[0020] The preparation method of the nylon masterbatch in this embodiment is the same as that in Embodiment 1.

[0021] Example 3 This embodiment provides a nylon masterbatch suitable for twin-screw cleaning, comprising the following components by weight percentage: 1% basic zinc carbonate, 0.2% zinc acetate, 0.1% stearic acid, and 98.7% PA6 chips.

[0022] The preparation method of the nylon masterbatch in this embodiment is the same as that in Embodiment 1.

[0023] Verification of the effect of machine cleaning The nylon masterbatch and PA6 chips prepared in Examples 1-3 were added to a twin-screw extruder coated with dark pigment. The temperature was set to 230°C, and the screw was cleaned through the extruder. The grayness of the extrudate was measured at 30 minutes (t1), 45 minutes (t2), and 60 minutes (t3). The test results are shown in Table 1. As can be seen from Table 1, the introduction of basic zinc carbonate into the PA6 substrate significantly improved the efficiency of PA6 chips in cleaning the screw. Furthermore, Examples 1-3 show that the content of basic zinc carbonate affects the screw cleaning rate; within a certain range, the higher the content of basic zinc carbonate, the better the screw cleaning effect.

[0024] Table 1. Cleaning effect of different masterbatches on the screw

[0025] The initial ash content of the samples in Examples 1-3 was 5.9%, 2.9% and 0.6%, respectively, and the ash content of the extrudate included the original ash content of the samples in each example.

[0026] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A nylon masterbatch for twin-screw cleaning, characterized in that: It includes the following components by weight percentage: 1-10% carbonate, 0.3-3% temperature regulator, and 87-98.7% PA6 chips.

2. The nylon masterbatch for twin-screw cleaning as described in claim 1, characterized in that: The temperature regulator is a compound of acetate and stearic acid.

3. The nylon masterbatch for twin-screw cleaning as described in claim 1, characterized in that: The carbonate is basic zinc carbonate or / and zinc carbonate.

4. The nylon masterbatch for twin-screw cleaning as described in claim 2, characterized in that: The acetate is zinc acetate.

5. A method for preparing nylon masterbatch for twin-screw cleaning as described in any one of claims 1-4, characterized in that: The carbonate and temperature regulator were mixed evenly and added to the side feed hopper, while PA6 chips were added to the main feed hopper. After being melt-blended by a twin-screw extruder, the mixture was extruded and granulated to obtain clean nylon masterbatch. The preparation process was carried out at 210℃.

Images