A high-content lubricant nylon masterbatch and its preparation method

Abstract

The present invention relates to the field of nylon masterbatch, and particularly to a high-content lubricant nylon masterbatch and a preparation method thereof. In this preparation method, the raw material components are fed into a twin-screw extruder, and the nylon masterbatch is obtained after co-blending, melting and extrusion. By weight, the raw material components include 55-65 parts of polyamide resin, 30-40 parts of lubricant, and 0.3-0.5 parts of other additives. The screw blocks in the melting and plasticizing section of the twin-screw extruder sequentially include a forward shear screw block, a reverse shear screw block, and a reverse conventional conveying screw block along the material conveying direction. The screw blocks in the mixing section sequentially include a forward conventional conveying screw block, a forward shear screw block, a reverse shear screw block, and a reverse conventional conveying screw block along the material conveying direction. This preparation method can improve production capacity, reduce the generation of dust and gas during the processing, is not easy to accumulate powder at the side feeding position, there is no material leakage at the exhaust port and the vacuum port, and the material strip discharging is continuous, and the particle cross-section is neat.

Description

Technical Field

[0001] The present invention relates to the field of nylon masterbatches, and particularly to a high-content lubricant nylon masterbatch and a preparation method thereof. Background Art

[0002] PA6, also known as nylon 6, is a semi-transparent or opaque milky white particle, with characteristics such as thermoplasticity, light weight, good toughness, good chemical resistance, and good durability.

[0003] The nylon masterbatch modified by adding a high content of lubricant can be directly injection-molded, with the advantages of low operation difficulty, convenient production, and no dust pollution. Due to its high fluidity, it is widely used in fields such as nylon material modification extrusion and injection molding.

[0004] However, for the nylon masterbatch modified by adding a high content of lubricant, its formulation contains a relatively large content of internal lubricant, external lubricant, and antioxidant. In this field, calcium stearate, erucamide, etc. are mostly selected as external lubricants. Therefore, there are the following disadvantages during the processing:

[0005] With a large amount of lubricant, the material is prone to slip in the screw barrel, resulting in low production capacity; it is easy to have material overflow at the vacuum port or exhaust port; the plasticization effect is poor, the particle cross-section has a trailing tail and a lot of powder during pelletizing; the strip extrusion is intermittent and easy to break.

[0006] To solve the deficiencies and defects of the existing solutions mentioned in the above background art, the present invention provides a preparation method of a high-content lubricant nylon masterbatch.

[0007] The technical solution of the preparation method of the high-content lubricant nylon masterbatch is as follows:

[0008] It feeds the raw material components into a twin-screw extruder, and after co-mixing and melting and extrusion, a nylon masterbatch is obtained; by weight, the raw material components include 55-65 parts of polyamide resin, 30-40 parts of lubricant, and 0.3-0.5 parts of other additives;

[0009] The twin-screw extruder sequentially includes a feeding section, a melting and plasticizing section, a mixing section, an exhaust section, and a metering section along the material conveying direction; the thread blocks of the melting and plasticizing section sequentially include a forward shearing thread block, a reverse shearing thread block, and a reverse conventional conveying thread block along the material conveying direction; the thread blocks of the mixing section sequentially include a forward conventional conveying thread block, a forward shearing thread block, a reverse shearing thread block, and a reverse conventional conveying thread block along the material conveying direction.

[0010] In one embodiment, a main feeding port is provided on the feeding section, a side feeding port is provided on the mixing section, the polyamide resin and other additives are fed from the main feeding port, and the lubricant is fed from the side feeding port.

[0011] In one embodiment, the melting and plasticizing section is successively composed of the following thread blocks along the material conveying direction: K45 / 56×3, K45 / 72 ×1, K90 / 56×1, K45 / 56L×1, 44 / 22L×1.

[0012] In one embodiment, the kneading section is successively composed of the following thread blocks along the material conveying direction: 96 / 96×7, 72 / 72 ×4, 64 / 64 ×2, 56 / 56 ×1, 44 / 44×2, K45 / 72×1, K45 / 56 ×1, K45 / 44 ×4, K90 / 44 ×1, K45 / 44L×2, 44 / 22L×2.

[0013] In one embodiment, the feeding section successively includes a positive conventional conveying type thread block, a positive deep groove thread block, and a positive conventional conveying type thread block along the material conveying direction; the exhaust section includes a positive conventional conveying type thread block; the metering section includes a positive conventional conveying type thread block.

[0014] In one embodiment, the feeding section is successively composed of the following thread blocks along the material conveying direction: 56 / 56A×1, 96 / 96SK ×2, 96 / 96SKN×1, 96 / 96 ×1, 72 / 72 ×1, 64 / 64 ×1;

[0015] The exhaust section is successively composed of the following thread blocks along the material conveying direction: 96 / 96 ×2, 72 / 72 ×1; the metering section is successively composed of the following thread blocks along the material conveying direction: 72 / 72 ×1, 64 / 64 ×1, 44 / 44 ×2.

[0016] In one embodiment, the length-diameter ratio of the screw of the twin-screw extruder is (44 - 56):1, the barrel temperature is 190°C - 260°C, and the screw speed is (500 - 600) rpm.

[0017] In one embodiment, the other additives include antioxidants; the polyamide resin is PA6;

[0018] By weight, the raw material components include 55 - 65 parts of polyamide resin, 30 - 40 parts of lubricant, and 0.3 - 0.5 parts of antioxidant.

[0019] In one embodiment, the last thread block of the twin-screw extruder protrudes from the screw shaft, and the length of the part of the thread block protruding from the screw shaft is less than one-half of the actual length of the thread block.

[0020] The present invention also provides a high-content lubricant nylon masterbatch, which is prepared by the preparation method of the high-content lubricant nylon masterbatch as described above.

[0021] The preparation method of the high-content lubricant nylon masterbatch provided by the present invention has the following beneficial effects compared with the prior art:

[0022] For the nylon masterbatch formula with a high content of lubricant, by rearranging and optimizing the screw elements in the melting and plasticizing section and the mixing section, without affecting the lubrication effect, the lubricant is fully dispersed and does not decompose, improving the production capacity; and during the processing, the melting and dispersion of the material at the side feeding port are improved, reducing the generation of dust and gas, and it is not easy to accumulate powder at the side feeding place, and there is no material overflow at the exhaust port and the vacuum port, improving the workshop environment; at the same time, during the processing, the material has good strip continuity, the particle cross-section is neat, there is no trailing, and there is little powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic diagram of the screw combination structure of Embodiment 1 provided by the present invention.

[0025] Reference Signs:

[0026]

[0027] Among them, the twin-screw extruder has a total of 13 barrels, and 1-13 respectively represent the 13 barrels. DETAILED DESCRIPTION OF THE INVENTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0029] The present invention provides a preferred implementation scheme for the preparation method of a high-content lubricant nylon masterbatch:

[0030] Feed the raw material components into a twin-screw extruder, and obtain the nylon masterbatch after blending, melting, and pelletizing. The specific steps are as follows:

[0031] (1) Weigh the raw material components according to a certain weight, and stir and mix the polyamide resin and the antioxidant in a high-speed mixer to obtain a mixture M;

[0032] (2) Feed the mixture M into the main feeding port 100 of the feeding section A of the twin-screw extruder, and the lubricant is fed through the side feeding port 200. Then, the raw material components are compounded, melted, extruded and pelletized in the twin-screw extruder to obtain the nylon masterbatch.

[0033] Among them, the twin-screw extruder sequentially includes a feeding section A, a melting and plasticizing section B, a kneading section C, an exhaust section D and a metering section E along the material conveying direction; the screw blocks of the melting and plasticizing section B sequentially include a forward shearing screw block, a reverse shearing screw block and a reverse conventional conveying screw block along the material conveying direction; the screw blocks of the kneading section C sequentially include a forward conventional conveying screw block, a forward shearing screw block, a reverse shearing screw block and a reverse conventional conveying screw block along the material conveying direction. Specifically: the melting and plasticizing section B is sequentially composed of the following screw blocks in combination: K45 / 56×3, K45 / 72 ×1, K90 / 56×1, K45 / 56L×1, 44 / 22L×1; the kneading section C is sequentially composed of the following screw blocks in combination: 96 / 96 ×7, 72 / 72 ×4, 64 / 64 ×2, 56 / 56 ×1, 44 / 44×2, K45 / 72×1, K45 / 56 ×1, K45 / 44 ×4, K90 / 44 ×1, K45 / 44L×2, 44 / 22L×2.

[0034] The present invention also provides a formula for the raw material components of the nylon masterbatch. By weight, the raw material components include: 55-65 parts of polyamide resin, 30-40 parts of lubricant, and 0.3-0.5 parts of antioxidant.

[0035] In summary, the above preparation scheme provided by the present invention at least includes the following inventive concepts and action mechanisms:

[0036] Aiming at the formula of the nylon masterbatch with a high content of lubricant, according to the characteristics of the high addition amount of the lubricant, the present invention adopts the optimized feeding method in combination with the screw combination method to solve the problems in the processing process: with a large amount of lubricant, the material is likely to slip in the barrel, resulting in low production capacity; the vacuum port 400 or the exhaust port 300 is likely to overflow; the plasticizing effect is poor, the particle cross-section has a tail during pelletizing, and there is a lot of powder; the strip output is intermittent and the strip is easily broken.

[0037] Among them, in the present invention, by optimizing the arrangement of the screw elements in the melting and plasticizing section B and the kneading section C and the feeding method, the screw blocks in the melting and plasticizing section B sequentially include a forward shearing screw block, a reverse shearing screw block, and a reverse conventional conveying screw block along the material conveying direction; the screw blocks in the kneading section C sequentially include a forward conventional conveying screw block, a forward shearing screw block, a reverse shearing screw block, and a reverse conventional conveying screw block along the material conveying direction. Among them, the conventionally arranged shearing elements (i.e., shearing screw blocks) are used to shear, mix, and melt the material, and the conventionally arranged conveying elements (i.e., conveying screw blocks) are used to convey the material, and pressure is established through the changes in the pitch and the screw groove. In the present invention, additional shearing screw blocks (such as K90 / 44, K90 / 56, etc.) are added, and specifically, a K45 / 44L type reverse shearing screw block is introduced to increase the back pressure, so that the lubricant is fully dispersed and does not decompose without affecting the lubrication effect, and the production capacity is improved. In addition, through the optimization of the feeding method, the polyamide resin and other additives are fed from the main feeding port 100, and the lubricant is fed from the side feeding port 200; in summary, for the nylon masterbatch formula with a high content of lubricant, through the above optimizations, the lubricant is fully dispersed and does not decompose without affecting the lubrication effect, and the production capacity is improved; and during the processing, the melting and dispersion of the material at the side feeding port 200 are improved, the generation of dust and gas is reduced, it is not easy to accumulate powder at the side feeding place, there is no material overflow at the exhaust port 300 and the vacuum port 400, and the workshop environment is improved; at the same time, during the processing, the material strip is continuous, the particle cross-section is neat, there is no trailing, and there is little powder.

[0038] The present invention also provides the following examples and comparative examples:

[0039] The following formula is adopted in the examples and comparative examples:

[0040] By weight, the raw material components include 64.7 parts of polyamide resin PA6, 35 parts of lubricant, and 0.3 parts of antioxidant. Specifically, 1 part is about 2 kg.

[0041] The screw combination method shown in Table 1 below is adopted for the screw extruder in the examples and comparative examples:

[0042] Table 1

[0043]

[0044] Among them, the order of the screw combination in Table 1 is from front to back along the material conveying direction; Figure 1 It is a schematic structural diagram of the co-rotating twin-screw extruder in Example 1 of the present invention.

[0045] The expression method of the screw block in this article is the conventional and general screw block model and parameter expression method in the art, specifically:

[0046] Positive conventional conveying type thread block expression: numerical value x / numerical value y × numerical value z, which represents numerical value z positive conventional conveying type thread blocks with a lead of numerical value x mm and an actual length of numerical value y mm. Among them, if there is no suffix of "× numerical value z", it indicates that there is only 1 positive conventional conveying type thread block. If the suffix "A" is added (i.e., numerical value x / numerical value y × numerical value zA), where "A" indicates that it is the starting element of the screw;

[0047] Negative conventional conveying type thread block expression: numerical value x / numerical value y L × numerical value z, which represents numerical value z negative conventional conveying type thread blocks with a lead of numerical value x mm and an actual length of numerical value y mm. Among them, "L" represents negative. If there is no suffix of "× numerical value z", it indicates that there is only 1 thread block;

[0048] Positive deep groove thread block expression: numerical value x / numerical value y SK × numerical value z, which represents numerical value z positive deep groove thread blocks with a lead of numerical value x mm and a length of numerical value y mm. The "SK" refers to the positive deep groove thread block, whose thread groove is deeper and the bottom of the thread groove has a taper. The "× numerical value z" represents numerical value z positive deep groove thread blocks. If there is no suffix of "× numerical value z", it indicates that there is only 1 thread block; numerical value x / numerical value y SKN represents a double-headed positive conventional conveying type thread block with a lead of numerical value x mm and a length of numerical value y. The "SKN" refers to the transition part from a deep groove thread element to a conventional thread element;

[0049] Positive shear thread block expression: K numerical value x / numerical value y / numerical value z × numerical value p, which represents numerical value p positive shear thread blocks, whose misalignment angle of the sheet-like shear slices is numerical value x°, the number of discs of the sheet-like shear slices is numerical value y, and the actual length of the shear thread block is numerical value z mm; if there is no suffix of "× numerical value p", it indicates that there is only 1 thread block;

[0050] Negative shear thread block expression: K numerical value x / numerical value y / numerical value z L × numerical value p, which represents numerical value p negative shear thread blocks, whose misalignment angle of the sheet-like shear slices is numerical value x°, the number of discs of the sheet-like shear slices is numerical value y, and the actual length of the shear thread block is numerical value z mm. Among them, "L" represents negative; if there is no suffix of "× numerical value p", it indicates that there is only 1 thread block;

[0051] The calculation formula for the shear unit angle x° of the positive shear thread block and the negative shear thread block is: 180° / (numerical value y - 1), where numerical value y represents the number of discs of the sheet-like shear slices is numerical value y; therefore, the expression of the positive shear thread block is abbreviated as: K numerical value x / numerical value z × numerical value p, and the expression of the negative shear thread block is abbreviated as: K numerical value x / numerical value z L × numerical value p.

[0052] TME represents the pitch diameter disc element or the tooth profile disc element; the expression of the pitch diameter disc thread block: TME value x × value y, which represents a set (a set is value y blocks) of tooth profile disc elements with a lead of xmm.

[0053] It should be noted that: according to the general expression of thread elements in this field, "L" and "SK" respectively indicate that the thread element is reverse and deep groove; among them, the forward (right-handed) and conventional non-deep groove structures generally do not need to be marked. A thread element without a special mark for reverse (left-handed) respectively indicates that it is not a special reverse (left-handed), and a thread element without a special mark for deep groove respectively indicates that it is not a special deep groove type thread block; the "conventional conveying type thread block" shown in this article refers to a non-deep groove conveying type thread element.

[0054] The following preparation process was adopted in Example 1 and Comparative Example 2:

[0055] (1) Weigh the raw material components according to a certain weight, and stir and mix the polyamide resin and antioxidant in a high-speed mixer for 1 - 3 min to obtain mixture M;

[0056] (2) Feed mixture M into the main feeding port 100 of the feeding section A of the twin-screw extruder, and the lubricant passes through the side feeding port 200. Then, the raw material components are in the twin-screw extruder, and after blending, melting, extrusion, and water cooling, pellets are made to obtain nylon masterbatch;

[0057] Among them, the length-diameter ratio of the screw of the twin-screw extruder is 52:1, with a total of 13 sections of barrels (from zone 1 to zone 13 along the material conveying direction), the barrel temperature is 190°C - 260°C, and the screw speed is 550 rpm. As Figure 1 shown, the main feeding port 100 is located in the feeding section A, the side feeding port 200 is located in the mixing section C (on the 6th barrel), the exhaust port 300 is located on the 5th and 8th barrels, and the vacuum port 400 is located on the 12th barrel. Specifically, the temperatures of the barrels in zones 1 to 13 of the twin-screw extruder are 220°C, 260°C, 260°C, 250°C, 230°C, 210°C, 190°C, 190°C, 190°C, 190°C, 190°C, 225°C, 255°C in sequence along the material conveying direction.

[0058] The difference between the preparation steps adopted in Comparative Example 1 and those adopted in Example 1 lies in: the feeding method is different. In Comparative Example 1, all raw material components (including all polyamide resin and antioxidant) are added through the main feeding port 100.

[0059] The instruments and equipment and their models used in the above preparation and testing processes are shown in Table 2 below:

[0060] Table 2

[0061]

[0062] The processing and preparation processes of the examples and comparative examples were observed, and the results are shown in Table 3 below respectively:

[0063] Table 3

[0064]

[0065] It can be seen from the test results in Table 3 that:

[0066] In Comparative Example 1, the screw combination was not optimized, and all raw material components were added from the main feed port 100, resulting in abnormal situations: the main feed port 100 was prone to powder accumulation, and the production capacity was as low as 120 kg; material overflow occurred at the exhaust port 300 and the vacuum port 400, and adjusting the processing temperature did not have an obvious improvement effect; the strip extrusion was intermittent, there were many broken strips, and there were many long strips in the finished pellets; after cutting, the particle sizes were uneven.

[0067] In Comparative Example 2, the screw combination was adjusted and optimized on the basis of Comparative Example 1. Shearing thread blocks such as K90 / 44 and K90 / 56 were added to strengthen the plasticization of the material. The positions of the positive conventional conveying thread blocks with a lead of 96 and a lead of 72 were reduced and rearranged. A side feed port 200 was added. The polyamide resin and other additives were fed from the main feed port 100, and the lubricant was fed from the side feed port 200; however, the processing process of Comparative Example 2 was still not ideal, and abnormal situations occurred: there was a lot of smoke at the side feed port 200 and the exhaust port 300; powder was prone to accumulate at the side feed port 200, and there was slight material overflow at the exhaust port 300; during the strip drawing process, the strip extrusion continuity was poor and it was easy to break; the pelletizing effect was poor and there was a lot of powder.

[0068] In Example 1, by optimizing the arrangement of the screw elements in the melting and plasticizing section B and the mixing section C and the feeding method, a K45 / 44L type reverse shearing thread block was added on the basis of Comparative Example 2, the back pressure was increased, and the polyamide resin and other additives were fed from the main feed port 100, and the lubricant was fed from the side feed port 200; compared with Comparative Examples 1-2, its processing effect was significantly better: the production capacity was increased; the exhaust port 300 and the vacuum port 400 were normal and there was no material overflow; during the strip drawing process, the strip extrusion was smooth and there was no broken strip; the pelletizing effect was good, the particle cross-section was neat, there was no tailing, and there was little powder.

[0069] In summary, for the nylon masterbatch formulation with a high content of lubricant, the present invention optimizes the rearrangement of the screw elements in the melting and plasticizing section B and the kneading section C. Without affecting the lubrication effect, the lubricant is fully dispersed and does not decompose, thus improving the production capacity. Moreover, during the processing, the melting and dispersion of the material at the side feeding port 200 are improved, the generation of dust and gas is reduced, powder accumulation is not likely to occur at the side feeding position, there is no material overflow at the exhaust port 300 and the vacuum port 400, and the workshop environment is improved. At the same time, during the processing, the material strip discharging is continuous, the particle cross-section is neat, there is no trailing, and there is less powder.

[0070] It should be noted that:

[0071] The expression "in sequence along the material conveying direction" described herein is a commonly used expression for the order of screw elements in the art. As is well known in the art, in general, the order is defaulted to be expressed according to the material conveying direction, that is, the processing procedure sequence. That is, from the feeding section A - melting and plasticizing section B - kneading section C - exhaust section D to the metering section E is the conveying direction of the material from front to back.

[0072] In addition to the actual selections reflected in the above specific embodiments, the present invention mainly improves the process for nylon masterbatch with a high content of lubricant. For the addition, type selection, and ratio determination of other auxiliary agents and other raw material components in the raw material components of the nylon masterbatch, those skilled in the art can make adaptive adjustments, including but not limited to the actual selections reflected in the above embodiments.

[0073] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a high-content lubricant nylon masterbatch, characterized in that: The raw material components are fed into a twin-screw extruder, and after being blended, melted, and extruded, a nylon masterbatch is obtained; the polyamide resin is PA6; by weight, the raw material components include 55-65 parts of polyamide resin, 30-40 parts of lubricant, and 0.3-0.5 parts of antioxidant; The twin-screw extruder sequentially includes a feeding section, a melting and plasticizing section, a mixing section, a degassing section, and a metering section along the material conveying direction; the screw blocks in the melting and plasticizing section sequentially include a forward shearing screw block, a reverse shearing screw block, and a reverse conventional conveying screw block along the material conveying direction; the screw blocks in the mixing section sequentially include a forward conventional conveying screw block, a forward shearing screw block, a reverse shearing screw block, and a reverse conventional conveying screw block along the material conveying direction; A main feeding port is provided on the feeding section, and a side feeding port is provided on the mixing section. The polyamide resin and the oxidant are fed through the main feeding port, and the lubricant is fed through the side feeding port; The melting and plasticizing section is sequentially composed of the following screw blocks along the material conveying direction: K45 / 56×3, K45 / 72 ×1, K90 / 56×1, K45 / 56L×1, 44 / 22L×1; The mixing section is sequentially composed of the following screw blocks along the material conveying direction: 96 / 96 ×7, 72 / 72 ×4, 64 / 64 ×2, 56 / 56 ×1, 44 / 44×2, K45 / 72×1, K45 / 56 ×1, K45 / 44 ×4, K90 / 44 ×1, K45 / 44L×2, 44 / 22L×2; The feeding section is sequentially composed of the following screw blocks along the material conveying direction: 56 / 56A ×1, 96 / 96SK ×2, 96 / 96SKN×1, 96 / 96×1, 72 / 72 ×1, 64 / 64 ×1; The degassing section is sequentially composed of the following screw blocks along the material conveying direction: 96 / 96 ×2, 72 / 72 ×1; The metering section is sequentially composed of the following screw blocks along the material conveying direction: 72 / 72 ×1, 64 / 64 ×1, 44 / 44 ×2.

2. The preparation method of the high-content lubricant nylon masterbatch according to claim 1, wherein: The length-diameter ratio of the screw of the twin-screw extruder is (44-56):1, the barrel temperature is 190°C-260°C, and the screw speed is (500-600) rpm.

3. The preparation method of the high-content lubricant nylon masterbatch according to claim 1, characterized in that: The last screw block of the twin-screw extruder protrudes from the screw shaft, and the length of the part of the screw block protruding from the screw shaft is less than one-half of the actual length of the screw block.

4. A high-content lubricant nylon masterbatch, characterized in that: It is obtained by the preparation method of the high-content lubricant nylon masterbatch according to any one of claims 1-3.

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