Efficient lubricant as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer material auxiliaries, in particular to a high-efficiency lubricant, a preparation method and application thereof, the high-efficiency lubricant comprises a pentaerythritol monostearate-zinc complex, and the pentaerythritol monostearate-zinc complex is formed by complexing pentaerythritol monostearate and zinc ions; the chemical structure of pentaerythritol monostearate is C (CH2OH) 3CH2OOC (CH2) 16CH3. According to the efficient lubricant, through combination of a pentaerythritol monostearate-zinc complex and uncomplexed pentaerythritol monostearate, synergistic balance of internal and external lubrication is achieved, friction between PVC molecular chains can be reduced, friction between PVC melt and the surface of metal equipment can be reduced, and the service life of the metal equipment is prolonged. Therefore, the processing performance of the PVC is comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material additives, and specifically relates to an efficient lubricant, a preparation method thereof, and an application thereof in the processing of polyvinyl chloride (PVC). More specifically, the present invention relates to a pentaerythritol monostearate-zinc complex lubricating system, which can simultaneously provide an internal and external lubrication balance effect and a heat stability synergistic effect, and significantly improve the processing performance of PVC. Background Art

[0002] Polyvinyl chloride (PVC), as one of the most widely used general plastics globally, has been widely applied in fields such as pipes, profiles, cable sheaths, sheets, etc. In the processing of PVC, lubricants are indispensable processing aids, which can reduce the friction coefficient between PVC resins and between PVC and the surface of metal equipment, improve the processing fluidity of PVC, increase the processing efficiency, and improve the surface quality of products.

[0003] Currently, the commonly used PVC lubricants in industry are mainly divided into internal lubricants and external lubricants. The main function of internal lubricants is to act between PVC molecular chains, reduce the friction force between molecular chains, and lower the melt viscosity. Representative products include fatty acid esters, fatty acid amides, fatty alcohols, etc.; the main function of external lubricants is to act between the PVC melt and the surface of processing equipment, reduce the friction force between the melt and the metal surface. Representative products include polyethylene wax, paraffin wax, fatty acid metal soaps, etc.

[0004] In the prior art, pentaerythritol ester lubricants have been widely used in PVC processing due to their good thermal stability and lubrication performance. For example, pentaerythritol tetrastearate (PETS) is a commonly used lubricant with good external lubrication effect. However, such tetraester products often have poor compatibility with PVC resins and are prone to precipitation on the surface of products, affecting the surface quality and subsequent processing performance of products. At the same time, due to their fully esterified structure, traditional pentaerythritol tetraester products lack polar interaction with PVC resins, resulting in insufficient internal lubrication effect.

[0005] Another type of lubricant commonly used in PVC processing is products such as glycerol monostearate (GMS) or G60, etc. They have a certain internal lubrication effect, but relatively poor thermal stability, are prone to decomposition under high-temperature processing conditions, and have a long plasticization time, affecting production efficiency.

[0006] In recent years, researchers have found that partially esterified products of pentaerythritol (such as pentaerythritol monoester, diester, etc.) have both certain polar and non-polar characteristics due to the retention of some hydroxyl groups, and can provide both internal and external lubrication effects simultaneously. However, the existing products of partially esterified pentaerythritol still have the following problems in practical applications: 1) The balance between internal and external lubrication is not ideal enough to meet the requirements of different processing technologies; 2) Although the thermal stability is better than that of traditional internal lubricants such as monoglyceride, there is still room for improvement under high-temperature and long-time processing conditions; 3) The synergistic effect with other additives (such as heat stabilizers, plasticizers, etc.) is limited.

[0007] Metal soap lubricants, such as calcium stearate, zinc stearate, etc., are also widely used in PVC processing. They not only have good external lubrication effects but also can provide certain thermal stabilization effects. However, the compatibility of metal soap lubricants with PVC is poor, the internal lubrication effect is limited, and they are easy to precipitate on the surface of the products. Therefore, developing a PVC lubricant with both internal and external lubrication balance effects and thermal stability synergistic effects is of great significance for improving the processing performance of PVC, reducing processing energy consumption, and enhancing the product quality.

[0008] Based on the above analysis, there is an urgent need in this field to develop a new type of lubricant that can simultaneously provide internal and external lubrication balance effects and thermal stability synergistic effects to meet the diverse needs of PVC processing. Summary of the Invention

[0009] The purpose of the present invention is to solve the technical problems such as the unsatisfactory internal and external lubrication balance, limited thermal stability, and insufficient synergistic effect with other additives of existing PVC lubricants, and to provide a high-efficiency lubricant of pentaerythritol monostearate-zinc complex, its preparation method and application.

[0010] To achieve the above purpose, the present invention proposes the following technical solutions:

[0011] In the first aspect, the present invention provides a high-efficiency lubricant, and the high-efficiency lubricant includes a pentaerythritol monostearate-zinc complex, and the pentaerythritol monostearate-zinc complex is formed by the complexation of pentaerythritol monostearate with zinc ions; the chemical structure of the pentaerythritol monostearate is C(CH2OH)3CH2OOC(CH2) 16 CH3.

[0012] In a preferred embodiment of the present invention, the molar ratio of the hydroxyl group to zinc ions in the pentaerythritol monostearate-zinc complex is from 6:1 to 3:1. Within this molar ratio range, the formed complex can not only maintain good lubrication effects but also achieve stable thermal stability synergistic effects.

[0013] In another preferred embodiment of the present invention, the high-efficiency lubricant further comprises uncomplexed pentaerythritol monostearate, and the mass ratio of pentaerythritol monostearate-zinc complex to uncomplexed pentaerythritol monostearate is 20:80 to 50:50. By adjusting the ratio of the complex to the uncomplexed monoester, the internal and external lubrication balance effect of the lubricant can be flexibly controlled to meet the requirements of different PVC processing processes.

[0014] The high-efficiency lubricant of the present invention may further comprise an antioxidant, the antioxidant is selected from hindered phenols, hindered amines or a combination thereof, and the addition amount of the antioxidant is 0.05-0.5% of the total mass of the lubricant. The presence of the antioxidant can further improve the thermal stability and service life of the lubricant.

[0015] Preferably, the high-efficiency lubricant is in the form of solid powder with a particle size of 50-120 μm. This particle size range can ensure the uniform dispersion and processing performance of the lubricant in the PVC formulation.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned high-efficiency lubricant, comprising the following steps:

[0017] (1) Synthesize pentaerythritol monostearate: Using pentaerythritol and stearic acid as raw materials, carry out a selective esterification reaction in the presence of a catalyst to obtain pentaerythritol monostearate;

[0018] (2) Prepare the complex: Mix the pentaerythritol monostearate obtained in step (1) with a zinc salt in a solvent, adjust the pH value to 7.0-8.5, and carry out a complexation reaction to obtain a pentaerythritol monostearate-zinc complex;

[0019] (3) Product preparation: Mix the pentaerythritol monostearate-zinc complex obtained in step (2) with uncomplexed pentaerythritol monostearate in a predetermined ratio, add an antioxidant, dry and pulverize to obtain the high-efficiency lubricant.

[0020] In an embodiment of the present invention, in step (1), the catalyst is selected from at least one of an organic titanium catalyst, an organic tin catalyst, and an immobilized enzyme catalyst; the molar ratio of pentaerythritol to stearic acid is 4:1 to 5:1; the temperature of the esterification reaction is 60-200 °C. The selection of different catalysts can affect the selectivity and yield of the product, and the control of the molar ratio helps to improve the selectivity of the monoester.

[0021] Preferably, in step (2), the zinc salt is selected from at least one of zinc acetate, zinc sulfate, and zinc chloride; the solvent is a mixed solvent of ethanol / water, and the volume ratio of ethanol to water is 70:30 to 90:10; the temperature of the complexation reaction is 50 - 70°C, and the reaction time is 2 - 4 hours. Appropriate types of zinc salts and reaction conditions can ensure the formation efficiency and stability of the complex.

[0022] In a preferred embodiment of the present invention, in step (3), the pentaerythritol monostearate - zinc complex is mixed with uncomplexed pentaerythritol monostearate at a mass ratio of 20:80 to 50:50; the antioxidant is 2,6 - di - tert - butyl - p - cresol, and the addition amount is 0.1% of the total mass of the lubricant; the drying temperature is 40 - 60°C; the particle size of the pulverized product is 50 - 120 μm. Optimization of these parameters can ensure the quality and performance stability of the final product.

[0023] In a third aspect, the present invention provides the application of the above - mentioned high - efficiency lubricant in the processing of polyvinyl chloride, wherein the addition amount of the high - efficiency lubricant is 0.3 - 0.8% of the weight of polyvinyl chloride.

[0024] Preferably, the processing method of polyvinyl chloride is extrusion, injection molding, or calendering; the high - efficiency lubricant is used as both an internal and external lubricant. The high - efficiency lubricant of the present invention is particularly suitable for the production process of rigid polyvinyl chloride products, such as rigid pipes, profiles, sheets, or cable sheaths.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) The internal and external lubrication balance effect is significant: The high - efficiency lubricant of the present invention realizes the synergistic balance of internal and external lubrication through the combination of pentaerythritol monostearate - zinc complex and uncomplexed pentaerythritol monostearate, which can not only reduce the friction between PVC molecular chains but also reduce the friction between the PVC melt and the surface of metal equipment, thereby comprehensively improving the processing performance of PVC.

[0027] 2) The thermal stability synergistic effect is enhanced: Zinc ions form a complex with the hydroxyl groups in pentaerythritol monostearate, which not only maintains a good lubrication effect but also can act synergistically in the thermal stabilization process of PVC, capture HCl released during the thermal degradation of PVC, and improve the thermal stability of PVC. Experimental results show that the lubricant of the present invention can extend the thermal stability time of PVC by 20 - 30%.

[0028] 3) The processing efficiency is significantly improved: The high - efficiency lubricant of the present invention can shorten the plasticization time of PVC by 30 - 40%, significantly improving the production efficiency; at the same time, it can reduce the processing temperature by 5 - 10°C, achieving energy conservation and emission reduction.

[0029] 4) The quality of the product is significantly improved: For PVC products prepared with the high-efficiency lubricant of the present invention, the surface glossiness is increased by 15 - 20%, the surface exudation phenomenon is significantly reduced, and the overall quality of the product is significantly improved.

[0030] 5) Wide applicability: The high-efficiency lubricant of the present invention can be widely applied to the production processes of products such as rigid PVC pipes, profiles, sheets, cable sheaths, etc., with strong adaptability and good process compatibility.

[0031] 6) Environmentally friendly and safe: The raw materials of the high-efficiency lubricant of the present invention are widely sourced, the preparation process is simple, non-toxic and harmless, meeting environmental protection requirements. Description of the Drawings

[0032] Figure 1 It is a comparison chart of the plasticizing time of the high-efficiency lubricant of the present invention and the existing lubricant in PVC.

[0033] Figure 2 It is a comparison chart of the thermal stability of the high-efficiency lubricant of the present invention and the existing lubricant in PVC.

[0034] Figure 3 It is a comparison chart of the surface quality of PVC products prepared with the high-efficiency lubricant of the present invention and the existing lubricant.

[0035] Figure 4 It is a comparison chart of the appearance of MG-60 of the present invention and the existing lubricant.

[0036] Figure 5 It is another comparison chart of the surface quality of PVC products prepared with the high-efficiency lubricant of the present invention and the existing lubricant. Detailed Embodiments

[0037] The technical solutions of the present invention will be described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the protection scope of the present invention.

[0038] For experimental methods where specific conditions are not indicated in the embodiments, they are usually carried out according to conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise stated, the raw materials, reagents, etc. used in the embodiments can be obtained through commercial channels.

[0039] I. Raw Materials and Reagents

[0040] The main raw materials and reagents used in the embodiments of the present invention are as follows:

[0041] Pentaerythritol: industrial grade, purity ≥ 98%, Tianjin Guangfu Fine Chemical Research Institute;

[0042] Stearic acid: industrial grade, purity ≥ 95%, Shanghai Macklin Biochemical Co., Ltd.;

[0043] Tetrabutyl titanate: analytically pure, Tianjin Kemiou Chemical Reagent Co., Ltd.;

[0044] Immobilized Candida antarctica lipase B (Novozym 435): Novozymes (China) Investment Co., Ltd.;

[0045] Zinc acetate: analytically pure, Sinopharm Chemical Reagent Co., Ltd.;

[0046] 2,6-Di-tert-butyl-p-cresol (BHT): analytically pure, Aladdin Reagent (Shanghai) Co., Ltd.;

[0047] Ethanol: analytically pure, Sinopharm Chemical Reagent Co., Ltd.;

[0048] Toluene: analytically pure, Sinopharm Chemical Reagent Co., Ltd.;

[0049] tert-Butanol: analytically pure, Shanghai Macklin Biochemical Co., Ltd.;

[0050] Other conventional reagents are all analytically pure, Sinopharm Chemical Reagent Co., Ltd.;

[0051] Pentaerythritol monostearate (MG-60): The chemical structural formula is C(CH2OH)3CH2OOC(CH2) 16 CH3.

[0052] MG-60 has the chemical structural formula C(CH2OH)3CH2OOC(CH2) 16 CH3, with both non-polar fatty acid chains and polar hydroxyl groups, and theoretically can provide internal and external lubrication effects simultaneously.

[0053] II. Preparation of pentaerythritol monostearate

[0054] Example 1: Preparation of pentaerythritol monostearate by enzymatic catalysis

[0055] In a 500 mL three-necked round-bottom flask, add 68 g (0.5 mol) of pentaerythritol and 35.5 g (0.125 mol) of stearic acid, and the molar ratio is 4:1. Add 300 mL of tert-butanol as a solvent, and add 10 g of molecular sieve was added as a dehydrating agent, and 10 g of immobilized Candida antarctica lipase B (Novozym 435) was added as a catalyst. The reaction mixture was magnetically stirred in an oil bath at 60 °C under nitrogen protection for 48 hours. After the reaction, the enzyme and molecular sieve were recovered by filtration. After partially removing the solvent by reduced-pressure evaporation of the filtrate, 500 mL of ethyl acetate was added for dilution, and it was washed with water three times (150 mL each time). The organic phase was separated, dried over anhydrous sodium sulfate, filtered, and the solvent was removed from the filtrate by reduced-pressure evaporation. The residue was dissolved in a small amount of hot n-hexane, cooled for crystallization, the crystals were collected by filtration, washed twice with cold n-hexane, and vacuum dried at 50 °C for 12 hours to obtain 48.2 g of white crystalline powder with an HPLC purity of 96.5% and a yield of 95.2%.

[0056] The infrared spectrum of the product showed a strong absorption peak of the ester group C=O stretching vibration at 1735 cm -1 −1, and a broad absorption peak of the hydroxyl O-H stretching vibration near 3400 cm -1 −1; 1 The 1H-NMR spectrum further confirmed that the product was pentaerythritol monostearate with the structure C(CH2OH)3CH2OOC(CH2) 16 16CH3.

[0057] Example 2: Preparation of pentaerythritol monostearate by chemical catalysis

[0058] In a 500 mL three-necked round-bottom flask, 68 g (0.5 mol) of pentaerythritol and 35.5 g (0.125 mol) of stearic acid were added, and the molar ratio was 4:1. 200 mL of toluene was added as an azeotropic dehydrating agent, and 0.5 g of tetrabutyl titanate was added as a catalyst. The reaction flask was equipped with a Dean-Stark apparatus, a reflux condenser, and a thermometer. Under nitrogen protection, the reaction mixture was heated to reflux, and the temperature was maintained at 110 - 120 °C for 6 hours. During this period, the water generated by the reaction was continuously separated from the Dean-Stark apparatus. After the reaction (the acid value dropped below 5 mg KOH / g), the reaction mixture was cooled to about 80 °C, 3 g of activated carbon was added, and after stirring for 30 minutes, it was filtered while hot. The filtrate was cooled to room temperature, crystals precipitated, and it was filtered by suction and the crystals were washed with cold toluene. The obtained crystals were dissolved in hot ethanol, hot water was added until the solution became turbid, cooled for crystallization, filtered by suction, washed with a cold water-ethanol mixture (1:1), and vacuum dried at 50 °C for 24 hours to obtain 42.5 g of white powder with an HPLC purity of 92.8% and a yield of 84.0%.

[0059] Example 3: Preparation of pentaerythritol monostearate by chemical catalysis (improved process)

[0060] Referring to the method of Example 2, adjust the molar ratio of pentaerythritol to stearic acid to 5:1, change the catalyst to an organotin catalyst (dibutyltin dilaurate) of 0.6 g, control the reaction temperature at 130 - 140 °C, and extend the reaction time to 8 hours. Other conditions remain unchanged. Finally, 46.8 g of white powder is obtained, with an HPLC purity of 95.2% and a yield of 92.5%.

[0061] III. Preparation of Pentaerythritol Monostearate-Zinc Complex

[0062] Example 4: Zinc Acetate Complex Method

[0063] In a 500 mL three-necked round-bottom flask, add 40 g (0.1 mol) of pentaerythritol monostearate prepared in Example 1 and 200 mL of ethanol, and heat to 60 °C to completely dissolve it. Separately, take 7.3 g (0.033 mol) of zinc acetate dihydrate and dissolve it in 30 mL of water to obtain a zinc acetate solution. Slowly drip the zinc acetate solution into the ethanol solution of pentaerythritol monostearate. At this time, the molar ratio of hydroxyl groups to zinc ions is approximately 3:1. Adjust the pH value of the reaction system to 7.5 - 8.0 with 10% ammonia water solution, and stir and react at 60 °C for 3 hours. After the reaction is completed, cool the reaction mixture to room temperature, and a white precipitate is produced. Filter by suction, wash the precipitate 2 times with an ethanol-water mixture (9:1), and then wash it 1 time with a small amount of acetone, and vacuum dry it at 50 °C for 24 hours to obtain 39.5 g of white powder, with a yield of 92.3%.

[0064] Infrared spectrum analysis shows that compared with pentaerythritol monostearate, the hydroxyl absorption peak near 3400 cm-1 of the complex has changed significantly, and at the same time, the characteristic absorption peak of the Zn-O bond appears in the 500 - 600 cm-1 region, confirming the complexation of zinc ions with hydroxyl groups.

[0065] Example 5: Zinc Sulfate Complex Method

[0066] According to a method similar to that of Example 4, replace zinc acetate dihydrate with an equimolar amount of zinc sulfate heptahydrate (9.5 g, 0.033 mol), and keep other conditions unchanged. Finally, 38.2 g of white powder is obtained, with a yield of 89.3%. The infrared spectrum and thermogravimetric analysis results of the product are similar to those of Example 4, indicating that pentaerythritol monostearate-zinc complex has been successfully prepared.

[0067] Example 6: Zinc Chloride Complex Method

[0068] Following a method similar to Example 4, zinc acetate dihydrate was replaced with an equimolar amount of zinc chloride (4.5 g, 0.033 mol), the reaction temperature was adjusted to 55 °C, and the reaction time was extended to 4 hours. Other conditions remained unchanged. Finally, 37.8 g of white powder was obtained with a yield of 88.3%. The properties of the product were similar to those of Examples 4 and 5.

[0069] IV. Preparation of High-Efficiency Lubricant

[0070] Example 7: Preparation of High-Efficiency Lubricant (Complex / Monoester = 3:7)

[0071] Take 30 g of the pentaerythritol monostearate-zinc complex prepared in Example 4 and 70 g of the pentaerythritol monostearate prepared in Example 1, and mix them evenly. Add 0.1 g of 2,6-di-tert-butyl-p-cresol (BHT) as an antioxidant, mix in a high-speed mixer for 10 minutes, and then dry in a vacuum drying oven at 50 °C for 6 hours. Crush the dried mixture with a jet mill, and control the particle size within the range of 80 - 100 μm to obtain 99.5 g of high-efficiency lubricant.

[0072] Example 8: Preparation of High-Efficiency Lubricant (Complex / Monoester = 4:6)

[0073] Take 40 g of the pentaerythritol monostearate-zinc complex prepared in Example 5 and 60 g of the pentaerythritol monostearate prepared in Example 2, and mix them evenly. Add 0.1 g of 2,6-di-tert-butyl-p-cresol (BHT) and 0.1 g of tetramethylpiperidine ether (Tinuvin 770) as antioxidants, and prepare the high-efficiency lubricant according to the method of Example 7 to obtain 99.6 g of the product.

[0074] Example 9: Preparation of High-Efficiency Lubricant (Complex / Monoester = 2:8)

[0075] Take 20 g of the pentaerythritol monostearate-zinc complex prepared in Example 6 and 80 g of the pentaerythritol monostearate prepared in Example 3, and mix them evenly. Add 0.15 g of 2,6-di-tert-butyl-p-cresol (BHT) as an antioxidant, and prepare the high-efficiency lubricant according to the method of Example 7 to obtain 99.7 g of the product.

[0076] Example 10: Preparation of High-Efficiency Lubricant (Complex / Monoester = 5:5)

[0077] Take 50 g of the pentaerythritol monostearate-zinc complex prepared in Example 4 and 50 g of the pentaerythritol monostearate prepared in Example 1, and mix them evenly. Add 0.2 g of 2,6-di-tert-butyl-p-cresol (BHT) and 0.1 g of a hindered amine antioxidant, and prepare the high-efficiency lubricant according to the method of Example 7 to obtain 99.8 g of the product.

[0078] V. Performance Testing of High-Efficiency Lubricants

[0079] Example 11: Plasticization Time Test

[0080] Prepare the standard PVC test formula as follows (unit: parts):

[0081] PVC resin (SG-5): 100;

[0082] Calcium carbonate: 30;

[0083] Heat stabilizer (calcium / zinc composite stabilizer): 3;

[0084] Lubricant: 0.5;

[0085] Titanium dioxide: 1.5;

[0086] Use the high-efficiency lubricants prepared in Examples 7-10, commercially available MG-60 lubricant, G60 lubricant, and monoglyceride as lubricants respectively to prepare four groups of test samples. Use a torque rheometer (RM200A) to test the plasticization time of each sample at 190 °C and 50 rpm. The test results are shown in Table 1.

[0087] Table 1 Plasticization Time Test Results of Different Lubricants

[0088]

[0089]

[0090] As can be seen from Table 1, compared with the commercially available MG-60, G60, and monoglyceride, the plasticization time of the high-efficiency lubricant prepared by the present invention is significantly shortened, and the shortening rate reaches 28.6%-39.7%. Among them, the plasticization time of Example 10 (complex / monoester = 5:5) is the shortest, only 76 seconds, which is 39.7% shorter than the commercially available MG-60. This shows that the high-efficiency lubricant of the present invention has a significant effect of improving processing efficiency.

[0091] Example 12: Thermal Stability Test

[0092] Use a PVC static thermal stability tester to test the thermal stability of various lubricants in PVC according to the ISO 182-1:1990 standard. The test conditions are 200 °C, and the test samples are the same as those in Example 11. The test results are shown in Table 2.

[0093] Table 2 Thermal Stability Test Results of Different Lubricants

[0094] Lubricant type Thermal stability time (min) Extension rate of thermal stability time relative to MG-60 (%) MG-60 42 - G60 38 -9.5 Mono-glyceride 36 -14.3 Example 7 53 26.2 Example 8 55 31 Example 9 51 21.4 Example 10 58 38.1

[0095] As can be seen from Table 2, compared with the commercially available MG-60, G60 and monoglyceride, the heat stability time of the high-efficiency lubricant prepared by the present invention is significantly prolonged, and the elongation rate reaches 21.4%-38.1%. Among them, Example 10 (complex / monoester = 5:5) has the longest heat stability time, reaching 58 minutes, which is 38.1% longer than the commercially available MG-60. This indicates that the high-efficiency lubricant of the present invention has a significant heat stability synergistic effect.

[0096] Example 13: Torque Test

[0097] The torque changes of each lubricant in PVC were tested using a torque rheometer (RM200A). The test conditions were 190°C and 50 rpm, and the test samples were the same as in Example 11. The test results are shown in Table 3.

[0098] Table 3 Torque Test Results of Different Lubricants

[0099] Lubricant type Maximum torque (N·m) Balanced torque (N·m) Torque fluctuation amplitude (%) MG-60 46.5 22.8 15.6 G60 48.2 23.5 18.4 Mono-glyceride 49.3 24.1 20.2 Example 7 42.3 21.5 8.2 Example 8 41.7 21.2 7.5 Example 9 43.5 21.8 9.6 Example 10 40.6 20.8 6.8

[0100] As can be seen from Table 3, compared with the commercially available MG-60, G60 and monoglyceride, the maximum torque and balance torque of the high-efficiency lubricant prepared by the present invention are both reduced, indicating better lubrication effect; more significantly, the torque fluctuation amplitude is greatly reduced, from 15.6% of the commercially available MG-60 to 6.8% of Example 10, a decrease of 56.4%. The reduction of the torque fluctuation amplitude means that the processing process is more stable and the product quality is more uniform.

[0101] Example 14: Evaluation of Product Surface Quality

[0102] Using the PVC formula in Example 11, different lubricants were added respectively, and PVC sheets were prepared by a laboratory extruder to evaluate the surface gloss and surface defects of the products. The extrusion conditions were: extrusion temperature 170-180°C, screw speed 45 rpm, and traction speed 3 m / min. After the prepared sheets were cooled, the 60° gloss was measured using a gloss meter (BYK-Gardner), and the surface defects were evaluated by visual inspection. The test results are shown in Table 4.

[0103] Table 4 Evaluation of Surface Quality of PVC Products Prepared with Different Lubricants

[0104]

[0105]

[0106] Surface defect evaluation criteria: "-" indicates no obvious defect; "+" indicates slight defect; "++" indicates medium defect; "+++" indicates obvious defect.

[0107] As can be seen from Table 4, compared with the commercially available MG-60, G60 and monoglyceride, the surface gloss of the PVC products prepared with the high-efficiency lubricant of the present invention is significantly improved, and the improvement rate reaches 11.6%-19.1%. Among them, the PVC product prepared in Example 10 (complex / monoester = 5:5) has the highest surface gloss, reaching 93.5, which is 19.1% higher than that of the commercially available MG-60. At the same time, the surface defects are also significantly reduced, especially the PVC product prepared in Example 10 has almost no visible surface defects. This indicates that the high-efficiency lubricant of the present invention can significantly improve the surface quality of PVC products.

[0108] Example 15: Long-term surface exudation test

[0109] The PVC sheet prepared in Example 14 was aged at 60°C for 30 days, and the surface exudation was observed. The aged sample was gently wiped with a cotton swab on the surface to observe whether there was white powder attached to the cotton swab, and the exudation degree was evaluated according to the following criteria: Grade 0 (no exudation), Grade 1 (slight exudation), Grade 2 (moderate exudation), Grade 3 (severe exudation). The test results are shown in Table 5.

[0110] Table 5 Long-term surface exudation test results of PVC products prepared with different lubricants

[0111]

[0112]

[0113] As can be seen from Table 5, compared with the commercially available MG-60, G60 and monoglyceride, the surface exudation after long-term use of the high-efficiency lubricant prepared by the present invention is significantly reduced. Especially for the PVC product prepared in Example 10 (complex / monoester = 5:5), even after 30 days of aging at 60°C, there is no obvious exudation on the surface. This indicates that the high-efficiency lubricant of the present invention has better compatibility with PVC resin and can significantly improve the long-term use performance of PVC products.

[0114] VI. Application of high-efficiency lubricant in PVC processing

[0115] Example 16: Application of high-efficiency lubricant in rigid PVC pipes

[0116] Prepare the rigid PVC pipe formula as follows (unit: part):

[0117] PVC resin (SG-5): 100;

[0118] Calcium carbonate: 15;

[0119] Heat stabilizer (methyltin type): 2.5;

[0120] High-efficiency lubricant (Example 10): 0.5;

[0121] Processing aid (acrylic processing aid): 1.0;

[0122] Titanium dioxide: 1.0;

[0123] Filler dispersant: 0.2;

[0124] Mix the above formula in a high-speed mixer, and control the mixing temperature at 110 - 115°C. After mixing evenly, extrude on a twin-screw extruder, and the extrusion temperature is 165 - 185°C. Use vacuum sizing technology to prepare PVC water supply pipes, and test the physical and mechanical properties and long-term service performance of the pipes. For comparison, use the same formula, and only replace the high-efficiency lubricant with commercially available MG-60 to prepare a comparative sample. The test results are shown in Table 6.

[0125] Table 6 Application effect of high-efficiency lubricant in rigid PVC pipes

[0126] Test item MG-60 Example 10 Standard requirement Tensile strength (MPa) 52.3 53.8 ≥45.0 Elongation at break (%) 138 142 ≥80 Vicat softening temperature (°C) 82.5 83.2 ≥80.0 Falling weight impact strength (qualified rate %) 90 95 ≥90 Processing extrusion speed (m / min) 15 18 - Processing energy consumption (kWh / kg) 0.42 0.35 - Processing stability (min)* 180 240 -

[0127] Processing stability refers to the time when the process parameters do not need to be adjusted or the die does not need to be cleaned during continuous extrusion.

[0128] As can be seen from Table 6, for the rigid PVC pipes prepared with the high-efficiency lubricant of the present invention (Example 10), all performance indexes meet or exceed the standard requirements. Moreover, compared with the pipes prepared with commercially available MG-60, the tensile strength and elongation at break are slightly improved, and the Vicat softening temperature and falling weight impact strength are also improved. More significantly, the processing performance is significantly improved: the extrusion speed is increased from 15 m / min to 18 m / min, an increase of 20%; the processing energy consumption is reduced from 0.42 kWh / kg to 0.35 kWh / kg, a reduction of 16.7%; the processing stability is extended from 180 min to 240 min, an extension of 33.3%. These data fully prove the remarkable effect of the high-efficiency lubricant of the present invention in improving the processing efficiency of rigid PVC pipes, reducing energy consumption and enhancing product quality.

[0129] Example 17: Application of high-efficiency lubricant in rigid PVC profiles

[0130] Prepare the following rigid PVC profile formula (unit: parts):

[0131] PVC resin (SG-8): 100;

[0132] Calcium carbonate: 12;

[0133] Heat stabilizer (calcium / zinc composite stabilizer): 3.0;

[0134] High-efficiency lubricant (Example 8): 0.6;

[0135] Processing aids (acrylic processing aids): 1.2;

[0136] Titanium dioxide: 4.0;

[0137] Filler dispersant: 0.3;

[0138] Impact modifier (CPE): 6.0;

[0139] Mix the above formula in a high-speed mixer, and control the mixing temperature at 115 - 120 °C. After mixing evenly, extrude on a special profile extruder, and the extrusion temperature is 175 - 190 °C. Prepare window frame profiles and test the physical and mechanical properties and processing properties of the profiles. As a comparison, use the same formula, and only replace the high-efficiency lubricant with commercially available MG-60 to prepare a comparative sample. The test results are shown in Table 7.

[0140] Table 7 Application effect of high-efficiency lubricant in PVC rigid profiles

[0141] Test item MG-60 Example 8 Standard requirement Tensile strength (MPa) 45.8 46.5 ≥42.0 <![CDATA[Impact strength (kJ / m 2 )]]> 12.3 12.8 ≥10.0 Vicat softening temperature (°C) 81.2 82 ≥80.0 Surface glossiness (60°) 82 92 ≥80 <![CDATA[Welding strength (N / mm 2 )]]> 25.5 26.8 ≥25.0 Extrusion stability rating (1-5 points)* 3.5 4.5 - Die pressure (MPa) 18.5 15.2 - Motor load rate (%) 75 65 -

[0142] Extrusion stability rating: 1 is the worst, 5 is the best, and the evaluation criteria include melt stability, extrusion surface quality, cross-section size stability, etc.

[0143] As can be seen from Table 7, for the PVC rigid profiles prepared using the high-efficiency lubricant of the present invention (Example 8), all performance indicators meet or exceed the standard requirements. Compared with the profiles prepared using commercially available MG-60, the tensile strength, impact strength, and Vicat softening temperature are slightly improved. In particular, the surface glossiness is increased from 82 to 92, an increase of 12.2%; the welding strength is increased from 25.5 N / mm 2 to 26.8 N / mm 2 , an increase of 5.1%. In terms of processing performance, the extrusion stability rating is increased from 3.5 to 4.5; the die pressure is reduced from 18.5 MPa to 15.2 MPa, a reduction of 17.8%; the motor load rate is reduced from 75% to 65%, a reduction of 13.3%. These data indicate that the high-efficiency lubricant of the present invention in the production of PVC rigid profiles can not only improve the product quality, but also significantly improve the processing performance, reduce energy consumption, and extend the service life of equipment and dies.

[0144] Example 18: Application of high-efficiency lubricant in PVC cable compounds

[0145] Prepare the PVC cable sheath compound formula as follows (unit: parts):

[0146] PVC resin (SG-5): 100;

[0147] Plasticizer (dioctyl phthalate): 40;

[0148] Filler (calcium carbonate): 20;

[0149] Heat stabilizer (calcium / zinc composite stabilizer): 2.5;

[0150] High-efficiency lubricant (Example 9): 0.4;

[0151] Antioxidant: 0.5;

[0152] Carbon black: 2.0;

[0153] Mix the above formula in a mixer, and control the temperature at 160 - 170 °C. After mixing evenly, granulate on a twin-screw extruder. Use the granulated material to prepare a cable sheath on a cable extruder, and test the physical and mechanical properties and electrical properties of the sheath. For comparison, use the same formula, and only replace the high-efficiency lubricant with commercially available MG-60 to prepare a comparative sample. The test results are shown in Table 8.

[0154] Table 8 Application effect of high-efficiency lubricant in PVC cable compound

[0155]

[0156]

[0157] Extrusion surface quality rating: 1 is the worst, 5 is the best, and the evaluation criteria include surface smoothness, bubbles, impurities, streaks, etc.

[0158] As can be seen from Table 8, for the PVC cable sheath compound prepared with the high-efficiency lubricant (Example 9) of the present invention, all performance indicators meet or exceed the standard requirements. Compared with the cable sheath compound prepared with commercially available MG-60, the tensile strength increases from 15.8 MPa to 16.2 MPa, the elongation at break increases from 320% to 335%, and the insulation resistance and breakdown voltage also increase. More significantly, the heat distortion rate decreases from 32% to 28%, and the retention rate of tensile strength after heat aging increases from 86% to 90%, indicating that the high-efficiency lubricant of the present invention can improve the thermal stability and aging resistance of the PVC cable sheath compound. In terms of processing performance, the extrusion temperature can be reduced by about 10 °C, and the extrusion surface quality rating increases from 3.8 to 4.6, indicating that the high-efficiency lubricant of the present invention can significantly improve the processing performance of the PVC cable sheath compound.

[0159] VII. Analysis of the action mechanism of the high-efficiency lubricant

[0160] The excellent performance of the high-efficiency lubricant of the present invention can be mainly explained from the following aspects:

[0161] 1. Internal and external lubrication balance mechanism:

[0162] Pentaerythritol monostearate (MG-60) has both a non-polar long-chain fatty acid part and a polar polyol hydroxyl part in its molecule, endowing it with an amphiphilic structural feature. Among them, the non-polar long-chain fatty acid part interacts with the PVC molecular chain, reducing the friction between PVC molecular chains and playing an internal lubrication role; the polar polyol hydroxyl part tends to migrate to the surface of the PVC melt, forming a boundary lubricating layer and reducing the friction between the PVC melt and the surface of metal equipment, playing an external lubrication role.

[0163] When a part of the hydroxyl groups in the MG-60 molecule are complexed with zinc ions to form a pentaerythritol monostearate-zinc complex, on the one hand, the introduction of zinc ions enhances the polarity of the molecule, making the complex more inclined to migrate to the surface of the PVC melt and enhancing the external lubrication effect; on the other hand, the coordination of zinc ions enables a certain degree of network structure to form between the complex molecules, and this network structure forms a more stable boundary lubricating layer on the surface of the PVC melt, further improving the external lubrication effect.

[0164] By regulating the ratio of the pentaerythritol monostearate-zinc complex to the uncomplexed pentaerythritol monostearate, the internal and external lubrication balance can be precisely regulated to meet the requirements of different PVC processing processes. The experimental results show that when the mass ratio of the pentaerythritol monostearate-zinc complex to the uncomplexed pentaerythritol monostearate is 50:50 (Example 10), the internal and external lubrication balance effect is the best and the PVC processing performance is the optimal.

[0165] 2. Thermal stability synergistic mechanism:

[0166] Zinc ions play an important thermal stability role in the PVC processing process. Traditional zinc soap-based heat stabilizers usually have poor compatibility with PVC and are prone to migrate to the PVC surface, resulting in surface precipitation and unsatisfactory stabilization effects.

[0167] In the high-efficiency lubricant of the present invention, zinc ions are effectively "fixed" on the pentaerythritol monostearate molecule by forming a complex with the hydroxyl groups in the pentaerythritol monostearate. This structure enables zinc ions to be evenly distributed in the PVC resin. When PVC undergoes a dechlorination reaction at high temperature to release HCl, zinc ions can promptly capture HCl, blocking the chain reaction of the dechlorination reaction, thereby significantly improving the thermal stability of PVC.

[0168] In addition, the uncomplexed hydroxyl groups in the pentaerythritol monostearate-zinc complex can also form hydrogen bond interactions with the PVC resin, enhancing the compatibility between the lubricant and the PVC resin, reducing surface precipitation, and further improving the long-term use performance of PVC products.

[0169] 3. Processing performance improvement mechanism:

[0170] The high-efficiency lubricant of the present invention significantly reduces the friction coefficient and melt viscosity of PVC resin during the processing by providing excellent internal and external lubrication balance effects, thereby reducing the processing torque and energy consumption. Meanwhile, the stable boundary lubricating layer reduces the friction between the PVC melt and the surface of the metal equipment, reduces the die pressure, and prolongs the die life.

[0171] The thermal stability synergistic effect of pentaerythritol monostearate-zinc complex improves the stability of PVC during high-temperature processing, reduces the generation of thermal degradation products, effectively avoids color change and gas release during the processing, and further improves the processing stability and the surface quality of the product.

[0172] The present invention provides a high-efficiency lubricant of pentaerythritol monostearate-zinc complex and its preparation method and application. Through the synergistic effect of pentaerythritol monostearate-zinc complex and uncomplexed pentaerythritol monostearate, the high-efficiency lubricant realizes the internal and external lubrication balance effect and the thermal stability synergistic effect, and significantly improves the processing performance of PVC and the quality of the product.

[0173] The high-efficiency lubricant of the present invention has the following main advantages:

[0174] 1) The internal and external lubrication balance effect is significant, which can reduce the friction between PVC molecular chains and the friction between the PVC melt and the surface of the metal equipment at the same time;

[0175] 2) The thermal stability synergistic effect is enhanced, which can effectively capture HCl released during the thermal degradation of PVC and improve the thermal stability of PVC;

[0176] 3) The processing efficiency is significantly improved, the plasticization time is shortened by 28.6%-39.7%, the processing temperature can be reduced by 5-10°C, and the energy consumption and emissions are significantly reduced;

[0177] 4) The quality of the product is significantly improved, the surface glossiness is increased by 11.6%-19.1%, and the surface bleeding phenomenon is significantly reduced;

[0178] 5) It has a wide range of applicability and can be widely used in the production processes of rigid PVC pipes, profiles, sheets, cable sheaths and other products;

[0179] 6) It is environmentally friendly and safe, has a wide range of raw material sources, a simple preparation process, is non-toxic and harmless, and meets the environmental protection requirements.

[0180] The high-efficiency lubricant of the present invention has a broad application prospect in the field of PVC processing, can effectively improve the production efficiency and quality of PVC products, reduce energy consumption, and meet the requirements of the green development of the industry.

[0181] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-efficiency lubricant, characterized in that: The high-efficiency lubricant comprises a pentaerythritol monostearate-zinc complex, wherein the pentaerythritol monostearate-zinc complex is formed by complexing pentaerythritol monostearate with zinc ions; the chemical structure of the pentaerythritol monostearate is C(CH2OH)3CH2OOC(CH2) 16 CH3.

2. The high-efficiency lubricant according to claim 1, characterized in that: The molar ratio of hydroxyl group to zinc ion in the pentaerythritol monostearate-zinc complex is 6:1 to 3:

1.

3. The high-efficiency lubricant according to claim 1 or 2, characterized in that: The high-efficiency lubricant further comprises uncomplexed pentaerythritol monostearate, wherein the mass ratio of the pentaerythritol monostearate-zinc complex to the uncomplexed pentaerythritol monostearate is 20:80 to 50:

50.

4. The high-efficiency lubricant according to any one of claims 1 to 3, characterized in that: The high-efficiency lubricant further comprises an antioxidant, which is selected from hindered phenols, hindered amines or a combination thereof, and the added amount of the antioxidant is 0.05-0.5% of the total mass of the lubricant.

5. The high-efficiency lubricant according to any one of claims 1 to 4, characterized in that: The high-efficiency lubricant is in the form of solid powder with a particle size of 50-120 μm.

6. A method for preparing the high-efficiency lubricant according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Synthesis of pentaerythritol monostearate: Pentaerythritol and stearic acid are used as raw materials, and a selective esterification reaction is carried out in the presence of a catalyst to obtain pentaerythritol monostearate; (2) preparing a complex: mixing the pentaerythritol monostearate obtained in step (1) with a zinc salt in a solvent, adjusting the pH value to 7.0-8.5, and performing a complex reaction to obtain a pentaerythritol monostearate-zinc complex; (3) Product preparation: The pentaerythritol monostearate-zinc complex obtained in step (2) is mixed with uncomplexed pentaerythritol monostearate in a predetermined ratio, an antioxidant is added, and the mixture is dried and crushed to obtain the high-efficiency lubricant.

7. The method according to claim 6, characterized in that In step (1), the catalyst is selected from at least one of an organic titanium catalyst, an organic tin catalyst, and an immobilized enzyme catalyst; the molar ratio of pentaerythritol to stearic acid is 4:1 to 5:1; and the temperature of the esterification reaction is 60-200°C.

8. The method according to claim 6, characterized in that In step (2), the zinc salt is selected from at least one of zinc acetate, zinc sulfate, and zinc chloride; the solvent is a mixed solvent of ethanol / water, and the volume ratio of ethanol to water is 70:30 to 90:10; the temperature of the complex reaction is 50-70° C., and the reaction time is 2-4 hours.

9. The method according to claim 6, characterized in that In step (3), the pentaerythritol monostearate-zinc complex and the uncomplexed pentaerythritol monostearate are mixed in a mass ratio of 20:80 to 50:50; the antioxidant is 2,6-di-tert-butyl-p-cresol, and the added amount is 0.1% of the total mass of the lubricant; the drying temperature is 40-60° C.; and the particle size of the product after pulverization is 50-120 μm.

10. Use of the high-efficiency lubricant according to any one of claims 1 to 5 in polyvinyl chloride processing, wherein the addition amount of the high-efficiency lubricant is 0.3-0.8% of the weight of the polyvinyl chloride, and the processing method of the polyvinyl chloride is extrusion, injection molding or calendering; the high-efficiency lubricant is used as an internal and external lubricant, and the polyvinyl chloride product is selected from hard pipes, profiles, sheets or cable sheaths.

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