Evaluation Method for Fluoropolymer Processing Aid PPA

Abstract

The present invention relates to the technical field of PPA analysis and detection, and specifically to a method for evaluating a fluoropolymer processing aid (PPA). The PPA evaluation method uses a carbon setting furnace to determine the thermal stability and applicable temperature of PPA, a small extruder to determine the plasticizing properties and applicable resin types of PPA, and a yellowness index meter to determine the effect of PPA on resin color, thereby determining the performance and applicable scope of the fluoropolymer processing aid (PPA). The evaluation method of the present invention can effectively determine the comprehensive performance of a polymer processing aid, as well as its performance, scope, and conditions of use. This provides accurate positioning for PPA product promotion, or enables PPA users to achieve differentiated purchasing and reduce usage costs.

Description

Technical Field

[0001] The present invention relates to the technical field of PPA analysis and detection, and in particular to an evaluation method for a fluoropolymer processing aid PPA. Background Art

[0002] Fluoropolymer processing aid PPA is an important plastic additive that can be used as a molding processing aid for polyolefins such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), cross-linked high-density polyethylene (XHDPE), cross-linked linear low-density polyethylene (XLLDPE), and polypropylene (PP). It has the functions of reducing production energy consumption, increasing output and production efficiency, improving product appearance, reducing apparent viscosity, reducing melt fracture, and eliminating die buildup.

[0003] However, as a mixed additive, PPA has a complex composition, with significant variations between different manufacturers and different types of PPA. Each PPA manufacturer maintains its product composition as a technical secret. While its composition can be characterized using methods like infrared and nuclear magnetic resonance, the effectiveness of its use cannot be effectively correlated with its composition. Furthermore, fluoropolymer processing aid PPA can undergo chemical or physical changes such as degradation, gumming, coking, and carbonization when exposed to high temperatures and shear. Poor performance, improper use, or a mismatch between the type and the intended use can lead to quality issues such as color difference, color-defective particles, and carbonized particles. Different PPA types also vary significantly in price, and purchasing PPA with excessive performance increases production costs.

[0004] Therefore, an effective evaluation method is urgently needed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an evaluation method for fluoropolymer processing aid PPA, which can effectively determine the comprehensive performance of polymer processing aids, determine their performance, scope of use and conditions of use, provide accurate positioning for the promotion of PPA products, or enable PPA users to achieve differentiated procurement and reduce usage costs.

[0006] The evaluation method for the fluoropolymer processing aid PPA described in the present invention uses a carbon determination furnace to determine the thermal stability and applicable temperature of PPA, uses a small extruder to determine the plasticizing property and applicable resin types of PPA, and uses a yellow index meter to determine the effect of PPA on resin color, thereby determining the performance and applicable range of the fluoropolymer processing aid PPA.

[0007] Specifically, the evaluation method of the fluoropolymer processing aid PPA comprises the following steps:

[0008] (1) 2-5g of PPA was placed in a carbon-fixing furnace, and the physical and chemical changes of color, phase state, and smoke were observed at different temperatures (typically 160℃-380℃) and different constant temperature times (typically 2min-10min). The thermal stability and applicable temperature of PPA, a fluoropolymer processing aid, were determined.

[0009] The temperature at which PPA begins to change color is the upper limit temperature for the use of this PPA, and it can be used at this temperature or below; the temperature at which PPA begins to gel, coke, or smoke is the limit temperature for the use of this PPA, and it cannot be used at this temperature or above.

[0010] After reaching the color change temperature, the color does not deepen significantly as the constant temperature time increases. This is because the variety is less affected by the processing load during use and the extrusion load can be flexibly adjusted during use. As the constant temperature time increases, the color continues to deepen. This is because the variety is greatly affected by the processing load during use and can only be used for high-load production.

[0011] (2) 0.01-0.20 wt% PPA was added to different polymer resins, and after mixing evenly, extrusion tests were carried out using small extruders. The extruder current was observed and compared with a blank sample without PPA added to determine the plasticizing properties of the fluoropolymer processing aid PPA and the types of resins it is suitable for.

[0012] The extrusion temperature of the small extruder is set at 170℃-230℃.

[0013] Under the same extrusion temperature and load, the smaller the extruder current, the better the PPA plasticizing effect.

[0014] Under the same extrusion temperature and load, when the extruder current reaches the same drop, the variety with less PPA addition has better plasticizing effect.

[0015] By testing different types of polymer resins separately and comparing them with blank samples, the resin type that can reduce the extruder current during the extrusion process is suitable for this PPA, or in other words, this PPA is suitable for this resin type.

[0016] (3) 0.01-0.20 wt% PPA was added to different polymer resins, and after mixing evenly, the mixture was continuously extruded 1-5 times using a small extruder. The yellow index of the extruded resin was then measured using a yellow index meter to determine the effect of the fluoropolymer processing aid PPA on the resin color.

[0017] Typical extruder extrusion temperature settings are 170°C-230°C.

[0018] The lower the yellowness index after a single extrusion, the less impact it has on the resin color and the better the performance. A yellowness index below -2 after a single extrusion indicates an indiscernible effect on the resin color and good performance. A yellowness index between -2 and 0 after a single extrusion indicates some impact on the resin color and average performance. A yellowness index above 0 after a single extrusion indicates a significant, visible impact on the resin color and poor performance. This PPA is not suitable for resins with specific color and color difference requirements. The smaller the increase in the yellowness index with increasing extrusion times, the better the performance.

[0019] By combining the tests in the above steps, the performance and application range of fluoropolymer processing aid PPA can be determined.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The evaluation method for fluoropolymer processing aid PPA of the present invention effectively determines the comprehensive performance of different varieties of fluoropolymer processing aid PPA, determines their usage performance, usage scope and usage conditions, and screens out suitable fluoropolymer processing aid PPA varieties for different polyolefin resin products, different granulation equipment, and different granulation temperatures, providing accurate positioning for the promotion of PPA products, or realizing differentiated procurement by PPA users, thereby reducing usage costs. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described in detail below. The equipment models used in the embodiments are as follows:

[0023] Carbon setting furnace: CARBOLITE single-tube carbon setting furnace from the UK

[0024] Small extruder: Jiangsu Jinwo Machinery Co., Ltd. JWP25 twin-screw extruder

[0025] Yellowness Index Meter: BYK Gardner Model 9000 Yellowness Index Meter (USA)

[0026] Example

[0027] From March to May 2020, the company used the evaluation method of the present invention to screen out PPA varieties suitable for metallocene polyethylene film materials, metallocene PERT pipe materials, and polypropylene PPR pipe materials.

[0028] A total of six fluoropolymer processing aids (PPAs) were selected for evaluation and labeled as PPA-1, PPA-2, PPA-3, PPA-4, PPA-5, and PPA-6.

[0029] The evaluation steps are as follows:

[0030] (1) 3 ± 0.5 g of PPA was placed in a carbon-fixing furnace, and its physical changes in color, phase, and smoke were observed at different temperatures (typically 160°C-380°C) and different constant temperature times (typically 2 min-10 min). The thermal stability and applicable temperature of the fluoropolymer processing aid PPA were determined.

[0031] After testing, the thermal stability and applicable temperature of 6 fluoropolymer processing aids PPA are as follows:

[0032] PPA-1 has good thermal stability between 160℃-320℃, and its applicable temperature is 160℃-320℃;

[0033] PPA-2 has good thermal stability between 160℃-220℃, and its applicable temperature is 160℃-220℃;

[0034] PPA-3 has good thermal stability between 160℃-260℃, and its applicable temperature is 160℃-260℃;

[0035] PPA-4 has good thermal stability between 160℃-380℃, and its applicable temperature is 160℃-380℃;

[0036] PPA-5 has good thermal stability between 160℃-240℃, and its applicable temperature is 160℃-240℃;

[0037] PPA-6 has good thermal stability between 160℃-380℃, and its applicable temperature is 160℃-380℃.

[0038] (2) 0.05 wt% PPA was added to each of metallocene polyethylene film, metallocene PERT pipe, and polypropylene (PPR) pipe. After uniform mixing, extrusion tests were conducted using a small extruder. The extrusion parameters were set at 190°C, 382 rpm, and 17.1 Hz. The extruder current was observed and compared with a blank sample without PPA. The plasticizing properties of the fluoropolymer processing aid PPA and the applicable resin types were determined.

[0039] After testing, the extruder currents of 6 fluoropolymer processing aids PPA are as follows:

[0040] PPA-1 extruder current 6.7A, 6.7A, 6.7A;

[0041] PPA-2 extruder current 6.8A, 6.8A, 6.8A;

[0042] PPA-3 extruder current 6.4A, 6.4A, 6.4A;

[0043] PPA-4 extruder current 6.3A, 6.3A, 6.3A;

[0044] PPA-5 extruder current 6.8A, 6.8A, 6.8A;

[0045] PPA-6 extruder current 6.6A, 6.6A, 6.6A;

[0046] The plasticizing effect is PPA-4>PPA-3>PPA-6>PPA-1>PPA-2=PPA-5.

[0047] (3) 0.05 wt% PPA was added to the metallocene polyethylene film material, metallocene PERT pipe material, and polypropylene PPR pipe material, respectively. After mixing evenly, the materials were extruded continuously for three times using a small extruder. The set parameters were: extrusion temperature was set to 190°C, main engine speed was 382 rpm, and feed speed was 17.1 Hz. Then, a yellow index meter was used to measure the yellow index of the extruded resin and to determine the effect of the fluoropolymer processing aid PPA on the resin color.

[0048] After testing, the yellow index of 6 fluoropolymer processing aids PPA is as follows:

[0049] PPA-1: -2.79 / -1.71 / 0.77;

[0050] PPA-2: 2.18 / 3.41 / 5.08;

[0051] PPA-3: -0.46 / 0.81 / 2.43;

[0052] PPA-4: -3.85 / -3.06 / -1.72;

[0053] PPA-5: 1.94 / 3.11 / 4.74;

[0054] PPA-6:-3.17 / -2.64 / -0.69.

[0055] After the above evaluation, the comprehensive performance is PPA-4>PPA-6>PPA-1>PPA-3>PPA-5>PPA-2.

[0056] The PPA varieties that can be screened out for metallocene polyethylene film materials are: PPA-1, PPA-2, PPA-3, PPA-4, PPA-5, PPA-6

[0057] The PPA varieties suitable for metallocene PERT pipe materials are: PPA-1, PPA-3, PPA-4, and PPA-6.

[0058] The PPA varieties suitable for polypropylene PPR pipe materials are: PPA-4 and PPA-6.

Claims

1. A method for evaluating a fluoropolymer processing aid (PPA), characterized by: Use a carbon setting furnace to determine the thermal stability and applicable temperature of PPA, use a small extruder to determine the plasticizing property and applicable resin types of PPA, and use a yellowness index meter to determine the effect of PPA on resin color, thereby determining the performance and applicable range of PPA, a fluoropolymer processing aid. Specifically: Place 2-5g of PPA in a carbon setting furnace and observe the physical and chemical changes in color, phase state, and smoke at different temperatures and different constant temperature durations to determine the thermal stability and applicable temperature of PPA, a fluoropolymer processing aid. 0.01-0.20wt% PPA was added to different polymer resins, mixed evenly, and extrusion tests were conducted using small extruders. The extruder current was observed and compared with a blank sample without PPA. The plasticizing properties of the fluoropolymer processing aid PPA and the types of resins it is suitable for were determined. At the same extrusion temperature and load, the lower the extruder current, the better the plasticizing effect of PPA. 0.01-0.20wt% PPA was added to different polymer resins, mixed evenly, and extruded continuously for 1-5 times using a small extruder. The yellow index of the extruded resin was then measured using a yellow index meter to determine the effect of the fluoropolymer processing aid PPA on the resin color. The smaller the yellow index value after one extrusion, the smaller the impact on the resin color and the better the performance. The PPA with a smaller increase in yellow index with increasing extrusion times has better performance.

2. The evaluation method for fluoropolymer processing aid PPA according to claim 1, characterized in that: The temperature range is 160℃-380℃, and the constant temperature time is 2min-10min.

3. The evaluation method for fluoropolymer processing aid PPA according to claim 2, characterized in that: The temperature at which PPA begins to change color is the upper limit temperature for the use of this PPA, and the temperature at which PPA begins to gel, coke, or smoke is the limit temperature for the use of this PPA.

4. The evaluation method for fluoropolymer processing aid PPA according to claim 1, characterized in that: The extrusion temperature of the small extruder is set at 170℃-230℃.

5. The evaluation method for fluoropolymer processing aid PPA according to claim 4, characterized in that: If the yellow index after one extrusion is below -2, the performance is good; if the yellow index after one extrusion is between -2 and 0, the performance is average; if the yellow index after one extrusion is above 0, the performance is poor.