Plastic lubricant, preparation method and application

Abstract

The invention relates to the field of processing aids and lubricants thereof, in particular to a plastic lubricant and a preparation method and application thereof.The preparation method comprises the following steps that firstly, dodecanedioic acid and pentaerythritol are added into a reaction kettle provided with a stirring device and a heating system; fully and uniformly mixing under the conditions that the temperature is 190-250 DEG C and the stirring speed is 300-500 revolutions per minute, so as to carry out dehydration esterification reaction, and continuously stirring until a chemical balancing state is achieved; and cooling to 150 DEG C, spraying powder and sieving to finally obtain the finished product plastic lubricant. The plastic lubricant disclosed by the invention can keep excellent lubricating property in a high-temperature environment, effectively reduce the viscosity of a plastic melt and remarkably improve the fluidity. Meanwhile, good thermal stability and chemical stability are achieved, it is ensured that no adverse reaction is generated when the coating is in contact with a plastic matrix, the environmental protection requirement is met, and pollution to the environment is avoided.

Description

Technical Field

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

[0002] In key processes such as injection molding and extrusion molding of plastic processing, the fluidity of 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 evenly fill the mold cavity and ensure the dimensional accuracy and surface quality of the product. For example, when injecting plastic products with complex shapes, if the melt fluidity is poor, it may cause defects such as lack of material and bubbles in the product, seriously affecting the product's qualification rate.

[0003] Traditional lubricants show many shortcomings in high-temperature environments. They are often prone to decomposition or volatilization, which greatly reduces their original lubrication effect. As the lubrication performance decreases, plastics face a series of problems during processing. Defects may appear on the surface of the product, such as increased surface roughness and flow marks, which affect the appearance quality of the product and reduce its market competitiveness. At the same time, dimensional instability is also common. Due to uneven melt flow, the product may have dimensional deviations after cooling and shaping, which cannot meet the production requirements of high-precision products. In addition, processing energy consumption will also increase due to poor melt fluidity, because higher pressure and temperature are required to drive the plastic melt to flow in the mold or extruder, increasing production costs.

[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] In order to solve the above technical problems, the following technical solutions are adopted: A plastic lubricant 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.

[0007] The present invention proposes another technical solution: a method for preparing a plastic lubricant, comprising the following steps: 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.

[0008] Furthermore, the molar ratio of dodecanedioic acid to pentaerythritol is (1-1.05):1.

[0009] Furthermore, the screening process is performed by screening through a standard sieve to remove existing large particle impurities.

[0010] Furthermore, the dodecanedioic acid may be replaced by octadecanoic acid.

[0011] The present invention proposes another technical solution: an application of a plastic lubricant, taking the finished plastic lubricant obtained by the above-mentioned preparation method, and fully mixing the finished plastic lubricant with plastic particles at a ratio of 0.5%-3% of the 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; and then processing and molding through plastic processing equipment.

[0012] Furthermore, the plastic processing equipment is an injection molding machine or an extruder.

[0013] The above technical solution has the following beneficial effects: The present invention is a plastic lubricant, a preparation method and an application. The plastic lubricant of the present invention forms a hydroxyl-containing cyclic polymer. The hydroxyl structure has relatively good chemical bond compatibility and can interact well with the plastic matrix, enhancing the lubrication effect without affecting the chemical properties of the plastic. The quasi-cyclic structure provides a relatively stable chemical framework for the substance, making it difficult to decompose under high temperature conditions, ensuring its effectiveness during high temperature processing. The aliphatic macromolecular structure of pentaerythritol is an important factor in 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.

[0014] The plastic lubricant of the present invention has significant advantages over 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 stability of the product size, and meets the production requirements of high-precision products. In addition, since the viscosity of the plastic melt is reduced, the resistance in the processing process is reduced, thereby reducing the processing energy consumption, saving production costs for enterprises.

[0015] The plastic lubricant prepared by the present invention can maintain excellent lubrication performance under high temperature environment, effectively reduce the viscosity of plastic melt, and significantly improve fluidity. At the same time, it has good thermal stability and chemical stability, ensuring that no adverse reaction occurs when in contact with the plastic matrix, and meets environmental protection requirements and does not cause pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the accompanying drawings: FIG. 1 is a chemical equation diagram of the esterification reaction of dodecanedioic acid and pentaerythritol of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail by examples below. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0018] A plastic lubricant comprises a hydroxyl-type cyclic polymer formed by continuous polymerization of the esterification reaction product of dodecanedioic acid and pentaerythritol, wherein the hydroxyl-type cyclic polymer is polydipentaerythritol dodecanoate. The chemical reaction equation is as follows: Figure 1 shown.

[0019] The present invention proposes another technical solution: a method for preparing a plastic lubricant, comprising the following steps: 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.

[0020] Furthermore, the molar ratio of dodecanedioic acid to pentaerythritol is (1-1.05):1.

[0021] Furthermore, the screening process is performed by screening through a standard sieve to remove existing large particle impurities.

[0022] Furthermore, the dodecanedioic acid may be replaced by octadecanoic acid.

[0023] The present invention proposes another technical solution: an application of a plastic lubricant, taking the finished plastic lubricant obtained by the above preparation method, and fully mixing the finished plastic lubricant with plastic particles at a ratio of 0.5%-3% of the 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, the finished plastic lubricant is processed and formed by plastic processing equipment.

[0024] Furthermore, the plastic processing equipment is an injection molding machine or an extruder.

[0025] The following is further described by means of specific embodiments: Example 1. Raw material preparation: Accurately weigh appropriate amounts of dodecanedioic acid and pentaerythritol, wherein the molar ratio of dodecanedioic acid to pentaerythritol is 1:1.

[0026] Reaction process: After adding the raw materials to the reactor, set the heating temperature to 190°C and the stirring speed to 300 rpm. As the reaction proceeds, it is observed that the materials in the reactor are gradually mixed evenly, and dehydration esterification reaction begins to occur, and a small amount of water is generated and discharged. After continuous stirring for 8 hours, the progress of the reaction is detected by chemical analysis, and it is found that it is close to the chemical balance state. Continue stirring for 2 hours to ensure that the reaction is complete.

[0027] Post-treatment: The reaction product is cooled to 150°C and a specific powder spraying device is used to spray the powder to obtain a powdered intermediate product. The product is then sieved through a standard sieve to remove possible large particle impurities and obtain a finished plastic lubricant.

[0028] Performance Test: The lubricant was mixed with plastic particles at a ratio of 0.5% of the weight of the plastic raw material, and then processed on an injection molding machine. Testing of the molded products showed that their surface quality was significantly improved compared to when no lubricant was added, with the surface roughness reduced by about 30%, the qualified rate of dimensional accuracy within the specified tolerance range increased by 20%, and the processing energy consumption reduced by about 10%.

[0029] Control experiment: Take the same plastic raw material, do not add the lubricant of the present invention, and process it under the same injection molding process conditions. Detect the surface roughness, dimensional accuracy and processing energy consumption of the control product. The results show that the surface roughness of the control product is relatively high, there are obvious flow marks, the dimensional accuracy qualification rate is only about 60%, and the processing energy consumption is about 15% higher than that of the experimental group with the lubricant added.

[0030] Example 2. The steps of Example 1 were repeated, but the heating temperature was adjusted to 220°C, the stirring speed was increased to 400 rpm, and the reaction time was shortened to 6 hours (the reaction efficiency was improved by optimizing the reaction conditions). When the lubricant product was added to plastic particles at a ratio of 1.5% by weight of the plastic raw material for extrusion molding, the surface finish of the product was further improved, there was almost no flow mark phenomenon, the dimensional accuracy qualified rate reached more than 95%, and the processing energy consumption was reduced by 15% compared with the traditional process.

[0031] Control experiment: The same plastic raw material as in Example 2 was used, and a conventional lubricant (a certain brand of lubricant commonly used in the market) was used to mix according to the recommended addition amount (generally 1%-2%), and then extrusion molding was performed under the same extruder equipment and process parameters. The product was tested and found that its surface finish was not as good as that of the product using the lubricant of the present invention, there were slight flow marks, the dimensional accuracy qualified rate was about 85%, and the processing energy consumption was about 8% higher than that of the experimental group using the lubricant of the present invention.

[0032] Example 3. On the basis of Example 1, the raw material ratio was changed (the molar ratio of dodecanedioic acid to pentaerythritol was 1.05:1), the heating temperature was increased to 250°C, the stirring speed was maintained at 500 rpm, and the reaction time was 7 hours. When the prepared lubricant was 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 reached the best state, the surface gloss was significantly improved, the dimensional accuracy fully met the requirements of high-precision products, and the processing energy consumption was reduced by about 20%.

[0033] Control experiment: another commonly used plastic raw material (a different type of plastic from Example 3) was selected, and the lubricant of the present invention and another high-temperature lubricant (the control example product) were mixed 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). The processing and molding were carried out under the same injection molding equipment and process conditions. The two products were compared and tested, and the results showed that the surface gloss of the product using the lubricant of the present invention was higher, the dimensional accuracy was more stable, and the processing energy consumption was about 5% lower than that of the experimental group using the control example product.

[0034] Example 4. In order 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 a long-term production (continuous production for 100 hours) was carried out on a continuously running injection molding machine. Samples were taken every 10 hours to test the quality indicators (surface roughness, dimensional accuracy) and processing energy consumption of the products. The results showed that during the entire production process, the surface roughness of the products had a small fluctuation range (within ±5%), the dimensional accuracy was always maintained at a high level (the qualified rate was above 90%), and the processing energy consumption fluctuation was not obvious (within ±3%).

[0035] Control experiment: Using traditional lubricants to conduct long-term production tests under the same conditions on the same injection molding machine. The results show that as the production time increases, the surface roughness of the product gradually increases. After 50 hours of production, the surface roughness increases by about 20%, the dimensional accuracy pass rate drops to about 70%, and the processing energy consumption gradually increases. After 80 hours of production, it is about 12% higher than the initial energy consumption.

[0036] Example 5. The applicability of the lubricant of the present invention in different types of plastics was studied. Three different types of plastics (such as polypropylene, polyethylene, and polystyrene) were selected, and the lubricant prepared in Example 1 was added to the plastic raw materials in different proportions of 0.5%-3%, and then processed and molded under respective appropriate 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 plastic was tested. The results showed that in different plastics, the lubricant of the present invention can effectively improve the fluidity of the plastic, improve the surface quality and dimensional accuracy of the products, and the effect is more significant when the addition amount is 1%-2%, and the processing energy consumption is reduced to varying degrees (the reduction is between 10%-20%).

[0037] Control experiment: For each plastic, traditional lubricants were used in conventional addition amounts for processing and molding, and the product quality and processing energy consumption were compared. The results showed that in polypropylene injection molding, the surface roughness of the products processed with traditional lubricants was about 15% higher than that of the products processed with the lubricant of the present invention, the dimensional accuracy qualified rate was about 10% lower, and the processing energy consumption was 8% higher; in polyethylene extrusion molding, the surface gloss of the products processed with traditional lubricants was poor, the dimensional accuracy fluctuated greatly, and the processing energy consumption was about 10% higher than that of the products processed with the lubricant of the present invention; in polystyrene blow molding, the wall thickness uniformity of the products processed with traditional lubricants was not as good as that of the products processed with the lubricant of the present invention, and the processing energy consumption was also relatively high (about 12% higher).

[0038] Through comparison and optimization of multiple embodiments and control experiments, the optimal preparation conditions, use parameter range and advantages of the plastic lubricant of the present invention in different application scenarios are determined, providing strong data support for its wide application in the field of plastic processing.

[0039] 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 resistance and lubrication performance compared with traditional lubricants in high temperature (150-350°C) plastic processing applications.

[0040] The performance of existing lubricants on the market and the embodiments of the present application were evaluated at different temperatures.

[0041] The existing lubricant and the lubricant of this embodiment respectively add lead salt stabilizer to PC, and the decomposition behavior is analyzed in the range of 150-350°C. A series of different processing temperatures are set, such as 150°C, 220°C, 260°C, and 350°C, and thermogravimetric (TGA) analysis is performed. Each time, 100 mg of lubricant sample is taken. The specific results are shown in Table 1.

[0042] Table 1 Substance name 150℃TGA condition (unit: mg) 220℃TGA situation (unit: mg) 260℃TGA condition (unit: mg) 350℃TGA condition (unit: mg) Stearic acid 0 1.7 3.5 15 Glyceryl Monostearate (85%) 0 0.5 2.2 4.9 Glyceryl Monostearate (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-polypentaerythritol laurate (80%) 0 0 0.2 0.4 Example 2-polypentaerythritol laurate (80%) 0 0 0.3 0.5 Example 3 - Polypentaerythritol laurate (80%) 0 0 0.4 0.6 Example 4-polypentaerythritol laurate (80%) 0 0 0.3 0.5 Example 5 - Polypentaerythritol dodecanoate (80%) 0 0 0.3 0.4 From the above, it can be seen that the polydipentaerythritol dodecanoate of Examples 1-5 of the present application has good thermal stability at 150-350°C, and has significant advantages in high temperature resistance and lubricity.

[0043] 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 basically the same technical problems and achieve basically the same technical effects are all included in 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. The preparation method according to claim 2, characterized in that: The dodecanedioic acid may be replaced by octadecanoic acid.

6. 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.

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

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