A method for preparing a polyolefin low-melting-point additive master batch

Abstract

The polyolefin low-melting-point additive master batch is composed of the following raw materials in mass percentage: 48-78% of polyolefin resin; 20-50% of low-melting-point additive; 0.5-2% of processing aid; and 0-0.5% of antioxidant.The preparation method of the patent is that the low-melting-point additive is added in the mixing plasticizing section of the extruder, and the ZME screw element is fully utilized to accelerate the blending of the additive and the resin, so that the mixed resin of the polyolefin and the processing aid are matched, the production temperature of the functional master batch is effectively reduced, the loss of the additive is greatly reduced, the color difference and black spots of the master batch product are reduced, and the separation phenomenon of the additive in storage and transportation is reduced, so that the patent has very practical market application value.

Description

Technical Field

[0001] This invention belongs to the field of functional masterbatch preparation, specifically relating to a method for preparing polyolefin low-melting-point additive masterbatch. Background Technology

[0002] The market for products directly molded from polyolefin resins is enormous. Polyolefin resins possess characteristics such as low relative density, good mechanical strength, chemical resistance, good water resistance, and electrical insulation, making them suitable for various everyday plastic products, including films, woven plastics, pipes, and fibers. Since its introduction, polyolefin resins have maintained a high-speed growth trend. Among them, polyethylene resin and polypropylene resin are the most important raw material resins for plastic products with production volumes exceeding tens of thousands of tons. In 2022, my country's polyethylene production was approximately 25.4 million tons, and polypropylene production was approximately 29.65 million tons.

[0003] Plastic products generally refer to mixtures of resin and other additives, which are heated and shaped under certain conditions, then cooled, solidified, and trimmed. To meet the demands of high-performance consumers, plastic products often require enhanced properties such as weather resistance, antistatic properties, and slip properties. These functional requirements have driven the development of the functional additives industry for plastics.

[0004] Most polyolefin product manufacturers use single-screw extruders with specific die structures for molding and processing. This can only provide basic distribution and mixing capabilities, but cannot effectively provide good dispersion and mixing capabilities. As a result, functional additives are unevenly distributed in plastic products, affecting their performance in the products. This leads to substandard and unstable functional test results, which seriously hinders the development of high-performance polyolefin products.

[0005] Preparing additives into functional masterbatches is an effective way to solve the problem of additive dispersion. Currently, the functional masterbatch industry mostly uses a method of mixing additives and resins directly, feeding them from the main feed port of the extruder. This method fails to achieve the expected dispersion requirements in the prepared masterbatch products and leads to excessive additive loss. The main technical challenges are: the functional additives used in polyolefin resins are mostly low-molecular-weight organic additives, which differ significantly from the molecular weight and melting point of the masterbatch carrier resin, making uniform blending difficult; the polarity of polyolefin functional additives is generally greater than that of polyethylene or polypropylene resins, and during high-temperature extrusion processing, functional additives easily adhere to the inside of the extruder barrel and die, resulting in defective particles (black spots, color difference particles) in the masterbatch and additive accumulation at the die. Summary of the Invention

[0006] To address the above problems, this invention discloses a method for preparing polyolefin low-melting-point additive masterbatch.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] This invention provides a polyolefin low-melting-point additive masterbatch, composed of the following raw materials by mass percentage:

[0009] Polyolefin resin 48-78%;

[0010] Low melting point additives 20-50%;

[0011] Processing aids 0.5-2%;

[0012] Antioxidant 0-0.5%;

[0013] The processing aid is one of PPA, organosilicon polymer, or polytetrafluoroethylene additive.

[0014] Furthermore, the low-melting-point additive is one or two of HALS 3853, HALS 770, UV 2908, UV 531, GMS, ethoxylated alkylamine, erucamide, and oleamide.

[0015] Furthermore, the polyolefin resin is a blend of polypropylene resin and polyethylene resin in a mass ratio of 2:1 to 6:1.

[0016] Furthermore, the melt index of the blend is 1-20 g / 10 min, and the test conditions are 230 °C and 2.16 kg.

[0017] Furthermore, the antioxidant is one or two of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0018] The present invention also provides a method for preparing the polyolefin low-melting-point additive masterbatch as described above, comprising the following steps:

[0019] (1) Mix polypropylene resin, polyethylene resin, antioxidant and processing aids at room temperature for 5-10 minutes using a mixer, and add the mixed material from the main feed port of the extruder in proportion.

[0020] (2) The low melting point additive is pre-melted in a water bath and then added to the storage bin of the liquid metering scale. It is injected from the injection port of the extruder through the liquid metering pump in proportion.

[0021] (3) The uniformly plasticized material is extruded from the die of the extruder and then processed through stripping, water cooling, pelletizing and homogenization to prepare low melting point additive masterbatch.

[0022] Furthermore, the extruder is a co-rotating twin-screw extruder with a length-to-diameter ratio of 40-48. The injection port is located in the mixing and plasticizing section, which is equipped with four ZME threaded elements. The temperature of the conveying melt section is 160-220°C, the mixing and plasticizing section is 180-200°C, the metering section is 170-190°C, the die temperature is 180°C, and the extruder screw speed is 250-380 r / min.

[0023] Furthermore, in step (2), the pre-melting temperature is 80-95℃.

[0024] Furthermore, the storage silo, liquid metering pump, and pipeline of the liquid metering scale are temperature controlled at 80-90℃.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) The addition of low-melting-point additives can utilize barrel heat transfer and screw shearing to achieve a good melt state of the resin mixture in the front stage. The setting of 4-segment ZME screw elements can effectively increase the blending ability of liquid additives and melt. This greatly avoids the phenomenon of additives encapsulating resin powder in oil during the mixing and feeding process, which leads to a decrease in barrel heat transfer effect, material slippage on the screw surface, and a significant decrease in shearing force, resulting in the agglomeration of functional additives in the resin.

[0027] (2) Specific processing aids effectively isolate the material from the extrusion equipment, reduce the heat loss of the aid during extrusion processing, and reduce the effect of the aid gradually precipitating from the inside of the particles to the surface during the storage of functional masterbatch, which causes multiple problems such as clumping of functional masterbatch products and loss of aids.

[0028] (3) The polypropylene and polyethylene blend resins used have good compatibility. After being uniformly blended in the front section of the extruder, they have a good carrying capacity for functional additives and greatly reduce the precipitation of additives. Attached Figure Description

[0029] Figure 1 The diagram shows the state of the die opening after 10 hours of production of the polyolefin antistatic masterbatch prepared in Example 4 and Comparative Example 3 of this invention.

[0030] The left figure is Example 4, and the right figure is Comparative Example 3. Detailed Implementation

[0031] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Example 1

[0032] Formula composition

[0033] The required additives, HALS 3853, UV 2908, and B215 (AO1010 and AO168 = 1:2), are all from Suqian Liansheng Technology Co., Ltd.; the processing aid PPA 810X is from Daikin Fluorochemicals; and the carrier resin (polyolefin resin) is from Nanjing Refinery Co., Ltd. The formulation is as shown in Table 1 below.

[0034] Table 1

[0035]

[0036] Preparation process

[0037] Polypropylene resin, polyethylene resin, antioxidant, and PPA 810X were mixed at room temperature for 8 minutes in a mixer. The mixed material was added to the main feed port of the extruder in proportion. HALS 3853 and UV 2908 were fully melted in a 95℃ water bath and then injected into the mixing and plasticizing section of the sixth barrel using liquid injection. The extruder had a length-to-diameter ratio of 48, and the mixing and plasticizing section was equipped with four ZME elements. The temperatures of each part from the feed port to the outlet were set sequentially as follows: 165, 220, 220, 220, 200, 200, 200, 180, 180, 180℃. The die temperature was 180℃, and the extruder screw speed was 380 r / min. Polyolefin weather-resistant additive masterbatch 1 was obtained. Example 2

[0038] The formula composition is shown in Table 2 below.

[0039] Table 2

[0040]

[0041] The preparation process is the same as in Example 1, and polyolefin weather-resistant masterbatch 2 is obtained. Example 3

[0042] The formulation is the same as in Example 1.

[0043] Preparation process:

[0044] Polypropylene resin, polyethylene resin, antioxidant, and PPA 810X were mixed at room temperature for 8 minutes in a mixer. The mixed material was then added to the main feed port of the extruder in proportion. HALS 3853 and UV 2908 were fully melted in a 95℃ water bath and injected into the mixing and plasticizing section of the sixth barrel using liquid injection. The extruder had a length-to-diameter ratio of 44, and the mixing and plasticizing section was equipped with four ZME elements. The temperatures from the feed port to the outlet were set sequentially as follows: 165, 220, 220, 220, 200, 200, 180, 180, 180℃. The die temperature was 180℃, and the extruder screw speed was 250 r / min. Polyolefin weather-resistant masterbatch 3 was obtained.

[0045] Comparative Example 1

[0046] The formula composition is shown in Table 3 below.

[0047] Table 3

[0048]

[0049] Preparation process:

[0050] As in Example 1, polyolefin weather-resistant masterbatch 4 was prepared. Comparative Example 2

[0051] The formula composition is shown in Table 4 below.

[0052] Table 4

[0053]

[0054] Preparation process:

[0055] Polypropylene resin, polyethylene resin, UV2908, and antioxidant were uniformly mixed in a mixer. The mixed material was added to the main feed port of the extruder according to the specified ratio. HALS 3853 was fully melted in a 95℃ water bath and then injected into the mixing and plasticizing section of the sixth barrel using liquid injection. The extruder had a length-to-diameter ratio of 44. The mixing and plasticizing section was equipped with four ZME elements. The temperatures from the feed port to the outlet were set sequentially as follows: 165, 220, 220, 220, 200, 200, 180, 180, 180℃. The die temperature was 180℃, and the extruder screw speed was 380 r / min. Polyolefin weather-resistant masterbatch 5 was obtained.

[0056] Performance Test 1:

[0057] The above five groups of polyolefin weather-resistant masterbatches were applied to polypropylene injection molded parts for weather resistance evaluation. First, the polypropylene resin (PPB-MN28-GH), talc filler (2500 mesh), and gray masterbatch in the injection molded part formulation were prepared into corresponding modified materials using a twin-screw extruder. Then, the modified materials were mixed uniformly with polyolefin low-melting-point additive masterbatch in a certain proportion to obtain weather-resistant masterbatch 1 to weather-resistant masterbatch 5. Under the same injection molding conditions, each group of samples was injection molded into 20 standard color plates with a thickness of 160mm*60mm*2mm. Five plates were randomly selected and aged for 2000 hours according to the aging conditions of PV 3939:2008. The color difference value (∆E) of the color plates after aging was tested according to DIN 53236-1983. The variance of each group of samples was calculated and shown in Table 6. The raw material composition of the color plates is shown in Table 5.

[0058] Table 5

[0059]

[0060] Table 6

[0061]

[0062] The light stabilizers used in the weathering masterbatches are HALS 3853 and UV 2908, and the masterbatch concentration and the amount used in the finished product are consistent. The color difference values ​​for weathering masterbatches 1, 2, and 3 can be controlled to around 2.7. The variance of the data characterizes the deviation of the color difference value, which essentially reflects the dispersibility of the weathering additives in the color sample product. It can be seen that the variances of weathering masterbatches 1 and 2 are <0.1. After reducing the screw speed in the extrusion process, the dispersion effect of weathering masterbatch 3 is also slightly affected. However, after removing polyethylene resin or processing aids, the corresponding weathering masterbatches 4 and 5 have a significant impact on the dispersion of weathering additives, with color difference values ​​>3.3 and variance values ​​>0.2.

[0063] Performance Test 2

[0064] The above five groups of polyolefin weather-resistant masterbatches were placed in 500 mL beakers and left to stand at 50 °C for 24 h. The appearance of the masterbatches was observed and shown in Table 7.

[0065] Table 7

[0066]

[0067] Maintaining the masterbatch at a constant temperature of 50℃ for an extended period can effectively accelerate the precipitation effect of low-melting-point additives. It can be seen that the precipitation effect of weather-resistant masterbatch 1, weather-resistant masterbatch 2, and weather-resistant masterbatch 3 is significantly better than that of the comparative weather-resistant masterbatch 4 and weather-resistant masterbatch 5. The related phenomenon is positively correlated with the variance of weather resistance in the color chart. Example 4

[0068] Formula composition

[0069] The required additives: monoglycerides and amine ethoxide are from Hangzhou Yongsheng Plastic Antistatic Materials Factory; the processing aid siloxane polymer HG-600 is from Zhejiang Jiahua Fine Chemicals Co., Ltd.; and the carrier resin (polyolefin resin) is from Nanjing Refinery Company. The formulation is as shown in Table 8 below.

[0070] Table 8

[0071]

[0072] Preparation process

[0073] Polypropylene resin, polyethylene resin, and HG-600 were mixed at room temperature for 8 minutes in a mixer. The mixed material was then added to the main feed port of the extruder in proportion. GMS and amine ethoxide were fully melted in a 95°C water bath and injected into the mixing and plasticizing section of the sixth barrel using liquid injection. The extruder had a length-to-diameter ratio of 48, and the mixing and plasticizing section was equipped with four ZME elements. The temperatures of each part from the feed port to the outlet were set sequentially as follows: 165, 220, 220, 220, 200, 200, 200, 180, 180, 180°C. The die temperature was 180°C, and the extruder screw speed was 380 r / min. Polyolefin antistatic masterbatch 6 was obtained. Comparative Example 3

[0074] The formula composition is shown in Table 9.

[0075] Table 9

[0076]

[0077] Preparation process:

[0078] Polypropylene resin, polyethylene resin, and amine oxyacetylene were uniformly mixed in a mixer. The mixed material was added to the main feed port of the extruder according to the specified ratio. GMS was fully melted in a 95℃ water bath and then injected into the mixing and plasticizing section of the sixth barrel using liquid injection. The extruder had a length-to-diameter ratio of 44. The mixing and plasticizing section was equipped with four ZME elements. The temperatures of each part from the feed port to the outlet were set sequentially as follows: 165, 220, 220, 220, 200, 200, 180, 180, and 180℃. The die temperature was 180℃, and the extruder screw speed was 300 r / min. Polyolefin antistatic masterbatch 7 was obtained.

[0079] Polyolefin antistatic masterbatch 6 production 10h die opening Figure 1 The left image shows the die opening of polyolefin antistatic masterbatch produced in 2 hours. Figure 1 The image on the right.

[0080] Depend on Figure 1 As shown in the right figure, there is a "die accumulation" phenomenon. Due to the significant difference in polarity between the antistatic agent and the polyolefin resin, low-melting-point additives are prone to precipitate from the system, forming a "die accumulation" phenomenon. The accumulation amount increases with the extension of production time. This phenomenon leads to the unnecessary loss of antistatic agent, and the accumulated additives will gradually turn yellow and black, eventually adhering to the material strip, resulting in defective particles in the antistatic masterbatch product.

[0081] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A polyolefin low-melting-point additive masterbatch, characterized in that, It consists of the following raw materials by weight percentage: Polyolefin resin 48-78%; Low melting point additives 20-50%; Processing aids 0.5-2%; Antioxidant 0-0.5%; The processing aid is one of PPA, organosilicon polymer, or polytetrafluoroethylene additive; The low-melting-point additive is one or two of HALS 3853, HALS 770, UV 2908, UV 531, glyceryl monostearate, ethoxylated alkylamine, erucamide, and oleamide. Polyolefin resin is a blend of polypropylene resin and polyethylene resin in a mass ratio of 2:1 to 6:

1. The melt index of the blend was 1-20 g / 10 min, and the test conditions were 230℃ and 2.16 kg. The preparation method of the polyolefin low-melting-point additive masterbatch includes the following steps: (1) Mix polypropylene resin, polyethylene resin, antioxidant and processing aids in a mixer for 5-10 minutes, and add the mixed material from the main feed port of the extruder; (2) The low melting point additive is pre-melted in a water bath and then added to the storage bin of the liquid metering scale and injected from the injection port of the extruder through the liquid metering pump; (3) The uniformly plasticized material is extruded from the die of the extruder, and then prepared as low-melting-point additive masterbatch through strip drawing, water cooling, pelleting and homogenization; The extruder is a co-rotating twin-screw extruder with a length-to-diameter ratio of 40-48. The injection port is located in the mixing and plasticizing section, which is equipped with 4 ZME thread elements. The temperature of the conveying melt section is 160-220°C, the temperature of the mixing and plasticizing section is 180-200°C, the temperature of the metering section is 170-190°C, the die temperature is 180°C, and the screw speed of the extruder is 250-380 r / min. In step (2), the pre-melting temperature is 80-95℃.

2. The polyolefin low-melting-point additive masterbatch according to claim 1, characterized in that, The antioxidant is one or two of antioxidant 1010, antioxidant 168, and antioxidant 1076.

3. A method for preparing polyolefin low-melting-point additive masterbatch as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Mix polypropylene resin, polyethylene resin, antioxidant and processing aids in a mixer for 5-10 minutes, and add the mixed material from the main feed port of the extruder; (2) The low melting point additive is pre-melted in a water bath and then added to the storage bin of the liquid metering scale and injected from the injection port of the extruder through the liquid metering pump; (3) The uniformly plasticized material is extruded from the die of the extruder, and then prepared as low-melting-point additive masterbatch through strip drawing, water cooling, pelleting and homogenization; The extruder is a co-rotating twin-screw extruder with a length-to-diameter ratio of 40-48. The injection port is located in the mixing and plasticizing section, which is equipped with 4 ZME thread elements. The temperature of the conveying melt section is 160-220°C, the temperature of the mixing and plasticizing section is 180-200°C, the temperature of the metering section is 170-190°C, the die temperature is 180°C, and the screw speed of the extruder is 250-380 r / min. In step (2), the pre-melting temperature is 80-95℃.

4. The method for preparing a polyolefin low-melting-point additive masterbatch according to claim 3, characterized in that, The storage silo and liquid metering pump of the liquid metering scale are temperature controlled at 80-90℃.

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