A plastic lubricant, preparation method and application

Abstract

The present invention relates to the field of processing aids and lubricants, and specifically relates to a plastic lubricant, a preparation method and an application. The preparation method is as follows: First, dodecanedioic acid and pentaerythritol are added to a reaction kettle equipped with a stirring device and a heating system; under the conditions that the temperature is in the range of 190°C - 250°C and the stirring speed is 300 - 500 revolutions per minute, they are fully mixed evenly, so as to carry out a dehydration esterification reaction, and continuous stirring is carried out until a chemical balance state is achieved; then it is cooled to 150°C, and then undergoes powder spraying and sieving processes, and finally the finished plastic lubricant is obtained. The plastic lubricant of the present invention can maintain excellent lubricating performance in a high-temperature environment, effectively reduce the viscosity of the plastic melt, and significantly improve the fluidity. At the same time, it has good thermal stability and chemical stability, ensuring that no adverse reactions will occur when contacting with the plastic matrix, and meeting the environmental protection requirements without causing pollution to the environment.

Description

Technical Field

[0001] The present invention relates to the field of processing aids and lubricants, and particularly to a plastic lubricant, a preparation method and an application thereof. Background Art

[0002] In key processes such as injection molding and extrusion molding in plastic processing, the fluidity of the plastic melt at high temperature is directly related to the final quality of the product and the efficiency of the production process. Good fluidity helps the plastic to uniformly fill the mold cavity, ensuring the dimensional accuracy and surface quality of the product. For example, when injecting plastic products with complex shapes, if the melt fluidity is poor, defects such as material shortage and bubbles may occur in the product, seriously affecting the qualified rate of the product.

[0003] Traditional lubricants show many deficiencies in high-temperature environments. They tend to decompose or volatilize easily, which greatly reduces their original lubricating effect. With the decline of lubricating performance, plastics face a series of problems during processing. There may be defects on the surface of the product, such as increased surface roughness and flow marks, affecting the appearance quality of the product and reducing its market competitiveness. At the same time, dimensional instability is also relatively common. Due to uneven melt flow, the product may have dimensional deviations after cooling and solidification, unable to meet the production requirements of high-precision products. In addition, the processing energy consumption will also increase due to poor melt fluidity, because higher pressure and temperature are required to push the plastic melt in the mold or extruder, increasing the production cost.

[0004] In view of this, the present invention provides a plastic lubricant, a preparation method and an application thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a plastic lubricant, a preparation method and an application thereof in view of the deficiencies of the prior art.

[0006] To solve the above technical problems, the following technical solutions are adopted:

[0007] A plastic lubricant includes a hydroxyl cyclic polymer continuously polymerized from the esterification reaction product of dodecanedioic acid and pentaerythritol, and the hydroxyl cyclic polymer is dipentaerythritol dodecanoate.

[0008] The present invention proposes another technical solution: a preparation method of a plastic lubricant, including the following steps:

[0009] S1. First, add dodecanedioic acid and pentaerythritol to a reaction kettle equipped with a stirring device and a heating system;

[0010] S2. Mix thoroughly under the conditions that the temperature is in the range of 190°C - 250°C and the stirring speed is 300 - 500 revolutions per minute, thereby carrying out the dehydration esterification reaction, and continue stirring until the chemical balance state is achieved;

[0011] S3. Subsequently, cool to 150°C, and then go through the processes of powder spraying and sieving to finally obtain the finished plastic lubricant.

[0012] Furthermore, the molar ratio of dodecanedioic acid to pentaerythritol is (1 - 1.05):1.

[0013] Furthermore, the sieving process is carried out through a standard sieve to remove the existing large - particle impurities.

[0014] Furthermore, the dodecanedioic acid can be replaced by octadecanoic acid.

[0015] Another technical solution proposed by the present invention is: an application of a plastic lubricant. Take the finished plastic lubricant obtained by the above - mentioned preparation method. Before plastic processing, mix the finished plastic lubricant with plastic particles in a ratio of 0.5% - 3% of the weight of the plastic raw materials; ensure the uniformity during the mixing process so that the finished plastic lubricant is evenly dispersed in the plastic particles; then carry out processing and shaping through plastic processing equipment.

[0016] Furthermore, the plastic processing equipment is an injection molding machine or an extruder.

[0017] Due to adopting the above - mentioned technical solution, the following beneficial effects are achieved:

[0018] The present invention relates to a plastic lubricant, a preparation method and an application. The plastic lubricant of the present invention forms a hydroxyl - containing cyclic polymer. The structure of the hydroxyl group has relatively good chemical bond compatibility, can interact well with the plastic matrix, enhance the lubrication effect without affecting the chemical properties of the plastic. The cyclic structure provides a relatively stable chemical framework for this substance, making it not easy to decompose in a high - temperature environment, ensuring its effectiveness during high - temperature processing. The pentaerythritol aliphatic macromolecular structure is an important factor for providing good lubricity, and its macromolecular chain can play a role similar to a "ball bearing" in the plastic melt, effectively reducing the viscosity of the melt and promoting its flow.

[0019] The plastic lubricant of the present invention has significant advantages compared with traditional lubricants. In high - temperature plastic processing, it can significantly improve the appearance quality of the product, make the surface of the product smooth and flawless, and improve its surface finish. At the same time, it effectively improves the dimensional accuracy, ensures the dimensional stability of the product, and meets the production requirements of high - precision products. In addition, since it reduces the viscosity of the plastic melt and reduces the resistance during processing, it thus reduces the processing energy consumption and saves production costs for enterprises.

[0020] The plastic lubricant prepared by the present invention can maintain excellent lubricating performance in a high-temperature environment, effectively reduce the viscosity of the plastic melt, and significantly improve fluidity. At the same time, it has good thermal stability and chemical stability, ensuring that no adverse reactions occur when contacting with the plastic matrix, and meeting environmental protection requirements without causing pollution to the environment. Brief Description of the Drawings

[0021] The present invention will be further described below with reference to the accompanying drawings:

[0022] Figure 1 is a chemical equation diagram of the esterification reaction of dodecanedioic acid and pentaerythritol in the present invention. Detailed Embodiments

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below through embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0024] A plastic lubricant includes a hydroxyl cyclic polymer continuously polymerized from the esterification reaction product of dodecanedioic acid and pentaerythritol, and the hydroxyl cyclic polymer is dipentaerythritol dodecanoate. The chemical reaction equation is as Figure 1 shown.

[0025] The present invention proposes another technical solution: a preparation method of a plastic lubricant, including the following steps:

[0026] S1. First, add dodecanedioic acid and pentaerythritol to a reaction kettle equipped with a stirring device and a heating system;

[0027] S2. Under the conditions that the temperature is in the range of 190°C - 250°C and the stirring speed is 300 - 500 revolutions per minute, mix evenly to carry out the dehydration esterification reaction, and continuously stir until the chemical balance state is reached;

[0028] S3. Then cool to 150°C, and then go through the processes of powder spraying and sieving to finally obtain the finished plastic lubricant.

[0029] Furthermore, the molar ratio of the dodecanedioic acid to the pentaerythritol is (1 - 1.05):1.

[0030] Furthermore, the sieving process is carried out through a standard sieve to remove the existing large particle impurities.

[0031] Furthermore, the dodecanedioic acid can be replaced by octadecanoic acid.

[0032] The present invention provides another technical solution: an application of a plastic lubricant. Take the finished plastic lubricant obtained by the above preparation method. Before plastic processing, mix the finished plastic lubricant with plastic particles in a proportion of 0.5%-3% of the weight of the plastic raw materials; ensure uniformity during the mixing process so that the finished plastic lubricant is evenly dispersed in the plastic particles. Then, carry out processing and molding through plastic processing equipment.

[0033] Further, the plastic processing equipment is an injection molding machine or an extruder.

[0034] The following is further illustrated through specific examples:

[0035] Example 1. Raw material preparation: Accurately weigh appropriate amounts of dodecanedioic acid and pentaerythritol, and the molar ratio of dodecanedioic acid to pentaerythritol is 1:1.

[0036] Reaction process: After adding the raw materials to the reaction kettle, set the heating temperature to 190 °C and the stirring speed to 300 revolutions per minute. As the reaction proceeds, it is observed that the materials in the reaction kettle are gradually mixed evenly, and the dehydration esterification reaction begins, with a small amount of water generated and discharged. After continuously stirring and reacting for 8 hours, the reaction progress is detected by chemical analysis means and found to be close to the chemical balance state. Continue to stir for 2 hours to ensure complete reaction.

[0037] Post-treatment: Cool the reaction product to 150 °C, and perform powder spraying operation using specific powder spraying equipment to obtain a powdery intermediate product. Then, sieve through a standard sieve to remove possible large particle impurities to obtain the finished plastic lubricant.

[0038] Performance test:

[0039] Mix the lubricant with plastic particles in a proportion of 0.5% of the weight of the plastic raw materials and carry out processing and molding on an injection molding machine. Detect the molded products and find that their surface quality has been significantly improved compared with those without adding the lubricant. The surface roughness has been reduced by about 30%, the qualified rate of the dimensional accuracy within the specified tolerance range has increased by 20%, and the processing energy consumption has been reduced by about 10%.

[0040] Control experiment: Take the same plastic raw materials, do not add the lubricant of the present invention, and carry out processing and molding under the same injection molding process conditions. Detect the surface roughness, dimensional accuracy, and processing energy consumption of the control products. The results show that the control products have higher surface roughness, obvious flow marks, the qualified rate of dimensional accuracy is only about 60%, and the processing energy consumption is about 15% higher than that of the experimental group with added lubricant.

[0041] Example 2. Repeat the steps of Example 1, but adjust the heating temperature to 220 °C, increase the stirring speed to 400 revolutions per minute, and shorten the reaction time to 6 hours (improve the reaction efficiency by optimizing the reaction conditions). When the final lubricant product is added to the plastic particles at a ratio of 1.5% by weight of the plastic raw material for extrusion molding, the surface finish of the product is further improved, there is almost no flow mark phenomenon, the qualified rate of dimensional accuracy reaches more than 95%, and the processing energy consumption is reduced by 15% compared with the traditional process.

[0042] Control experiment: Use the same plastic raw material as in Example 2, use a traditional lubricant (a certain brand lubricant commonly used in the market), mix it according to its recommended addition amount (generally 1%-2%), and then carry out extrusion molding under the same extruder equipment and process parameters. The product is tested and it is found that its surface finish is inferior to that of the product using the lubricant of the present invention, there are slight flow marks, the qualified rate of dimensional accuracy is about 85%, and the processing energy consumption is about 8% higher than that of the experimental group using the lubricant of the present invention.

[0043] Example 3. On the basis of Example 1, change the raw material ratio (the molar ratio of dodecanedioic acid and pentaerythritol is 1.05:1), and increase the heating temperature to 250 °C, keep the stirring speed at 500 revolutions per minute, and the reaction time is 7 hours. When the prepared lubricant is added to the plastic at a ratio of 3% by weight of the plastic raw material for injection molding, the surface quality of the product reaches the best state, the surface gloss is significantly improved, the dimensional accuracy fully meets the requirements of high-precision products, and the processing energy consumption is reduced by about 20%.

[0044] Control experiment: Select another commonly used plastic raw material (a different type of plastic from that in Example 3), and mix the lubricant of the present invention and another high-temperature lubricant (the product of the control example) with the plastic raw material according to their respective recommended optimal addition amounts (3% for the present invention and 2.5% for the control example product). Process and mold under the same injection equipment and process conditions. The two products are compared and tested. The results show that the product using the lubricant of the present invention has a higher surface gloss, more stable dimensional accuracy, and the processing energy consumption is about 5% lower than that of the experimental group using the control example product.

[0045] Example 4. To further verify the stability of the lubricant of the present invention during long-term high-temperature processing, the lubricant prepared in Example 2 was added to the plastic raw material (the addition amount was 1.5%), and long-term production was carried out on a continuously operating injection molding machine (continuous production for 100 hours). Samples were taken every 10 hours to detect the quality indicators (surface roughness, dimensional accuracy) of the products and the processing energy consumption. The results showed that during the whole production process, the fluctuation range of the surface roughness of the products was small (within ±5%), the dimensional accuracy remained at a high level all the time (the qualified rate was above 90%), and the fluctuation of the processing energy consumption was not obvious either (within ±3%).

[0046] Control experiment: The traditional lubricant was used to conduct long-term production tests under the same conditions on the same injection molding machine. The results showed that as the production time extended, the surface roughness of the products gradually increased. After 50 hours of production, the surface roughness increased by about 20%. The qualified rate of the dimensional accuracy dropped to about 70%. The processing energy consumption also gradually increased. After 80 hours of production, it was about 12% higher than the initial energy consumption.

[0047] Example 5. To study the applicability of the lubricant of the present invention in different types of plastics. Three different types of plastics (such as polypropylene, polyethylene, polystyrene) were selected. The lubricant prepared in Example 1 was added to the plastic raw materials at different ratios of 0.5%-3% respectively, and then processed and formed under their respective suitable processing equipment and process conditions (such as injection molding for polypropylene, extrusion molding for polyethylene, and blow molding for polystyrene). The quality of the products processed from each type of plastic was detected. The results found that in different plastics, the lubricant of the present invention could effectively improve the fluidity of the plastics, improve the surface quality and dimensional accuracy of the products, and the effect was more significant when the addition amount was 1%-2%. The processing energy consumption was reduced to varying degrees (the reduction range was between 10%-20%).

[0048] Control experiment: For each type of plastic, the traditional lubricant was used for processing and forming according to the conventional addition amount, and the product quality and processing energy consumption were compared. The results showed that in the injection molding of polypropylene, the surface roughness of the products processed by the traditional lubricant was about 15% higher than that of the products processed by the lubricant of the present invention, the qualified rate of the dimensional accuracy was about 10% lower, and the processing energy consumption was 8% higher; in the extrusion molding of polyethylene, the surface gloss of the products processed by the traditional lubricant was poor, the dimensional accuracy fluctuated greatly, and the processing energy consumption was about 10% higher than that of the products processed by the lubricant of the present invention; in the blow molding of polystyrene, the wall thickness uniformity of the products processed by the traditional lubricant was not as good as that of the products processed by the lubricant of the present invention, and the processing energy consumption was also relatively high (about 12% higher).

[0049] Through the comparison and optimization of multiple embodiments and control experiments, the optimal preparation conditions, usage parameter ranges of the plastic lubricant of the present invention, and its advantages in different application scenarios are determined, providing strong data support for its wide application in the field of plastic processing.

[0050] Through the comparative experimental data and result analysis of the above multiple embodiments, it is fully and comprehensively confirmed that the plastic lubricant of the present invention has significant advantages in high-temperature (150 - 350 °C) plastic processing applications compared with traditional lubricants in terms of high-temperature resistance performance and lubrication performance.

[0051] The performance of the existing lubricants on the market and the embodiments of this application are compared at different temperatures.

[0052] The lead salt stabilizers added to the existing lubricants and the lubricants of this embodiment in PC are respectively analyzed for their decomposition behavior in the range of 150 - 350 °C. A series of different processing temperatures are set, such as 150 °C, 220 °C, 260 °C, 350 °C, and thermogravimetric (TGA) analysis is carried out. Each time, 100 mg of the lubricant sample is taken, and the specific results are shown in Table 1.

[0053] Table 1

[0054] Substance Name TGA at 150°C (unit: mg) TGA at 220°C (unit: mg) TGA at 260°C (unit: mg) TGA at 350°C (unit: mg) Stearic Acid 0 1.7 3.5 15 Monoglyceride Stearate (85%) 0 0.5 2.2 4.9 Monoglyceride Stearate (90%) 0 0.6 2.0 4.4 Pentaerythritol Stearate (90%) 0 0.2 1.3 3.9 Pentaerythritol Stearate (95%) 0 0.4 1.0 2.5 Ethylene Bisstearamide 0.5 2.0 4.7 18.9 Example 1 - Dipentaerythritol Dodecanoate (80%) 0 0 0.2 0.4 Example 2 - Dipentaerythritol Dodecanoate (80%) 0 0 0.3 0.5 Example 3 - Dipentaerythritol Dodecanoate (80%) 0 0 0.4 0.6 Example 4 - Dipentaerythritol Dodecanoate (80%) 0 0 0.3 0.5 Example 5 - Dipentaerythritol Dodecanoate (80%) 0 0 0.3 0.4

[0055] As can be seen from the above, the ditrimethylolpropane dodecanoate of Examples 1 - 5 of this application has good thermal stability in the range of 150 - 350 °C and has significant advantages in high-temperature resistance performance and lubrication performance.

[0056] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements, or modifications made based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are all covered by the protection scope of the present invention.

Claims

1. A plastic lubricant, characterized in that: The invention comprises a hydroxyl ring polymer formed by continuous polymerization of an esterification reaction product of dodecanedioic acid and pentaerythritol, wherein the hydroxyl ring polymer is polydipentaerythritol dodecanoate.

2. A method for preparing a plastic lubricant as claimed in claim 1, characterized in that The following steps are involved: S1. First, dodecanedioic acid and pentaerythritol are added to a reactor equipped with a stirring device and a heating system; S2. Mixing the mixture thoroughly at a temperature of 190°C to 250°C and a stirring speed of 300 to 500 rpm to carry out a dehydration esterification reaction, and continuing stirring until a chemically balanced state is achieved; S3. The mixture is then cooled to 150°C and subjected to powder spraying and sieving processes to finally obtain a finished plastic lubricant.

3. The preparation method according to claim 2, characterized in that: The molar ratio of dodecanedioic acid to pentaerythritol is (1-1.05):

1.

4. The preparation method according to claim 2, characterized in that: The screening process is performed by screening through a standard sieve to remove the large particles of impurities.

5. An application of a plastic lubricant, characterized in that: Take the finished plastic lubricant obtained by the preparation method of claim 2, and fully mix the finished plastic lubricant with plastic particles at a ratio of 0.5%-3% by weight of the plastic raw material before plastic processing; the mixing process must ensure uniformity so that the finished plastic lubricant is evenly dispersed in the plastic particles; Then it is processed and formed by plastic processing equipment.

6. The use of a plastic lubricant according to claim 5, characterized in that: The plastic processing equipment is an injection molding machine or an extruder.

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