Anti-sticking modified bopp masterbatch and preparation process thereof
By combining stearate modification with microcapsules, the problems of anti-sticking agent agglomeration and poor interfacial compatibility in BOPP films were solved, resulting in BOPP films with stable anti-sticking performance, high optical transparency, and good mechanical strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HANGZHOU BEISHENG POLYMERMATERIAL
- Filing Date
- 2026-04-13
- Publication Date
- 2026-06-09
AI Technical Summary
The morphology and particle size distribution of inorganic anti-sticking agents in existing BOPP films are not precise enough, leading to agglomeration, which affects the appearance and optical properties of the film. In addition, the interfacial compatibility between the carrier resin and the anti-sticking agent is poor, resulting in unstable anti-sticking effect.
A complex was formed by reacting stearate with a modifier, and a microcapsule foaming agent was prepared by in-situ polycondensation. The foaming agent was encapsulated in the shell of the microcapsule, and a uniform anti-sticking functional phase was formed by combining optimized segmented polymerization and controlled shear melt blending process.
Uniform dispersion of the anti-stick agent in the film was achieved. The microcapsules released gas in a controlled manner during the stretching process, forming submicron pores, which improved the anti-stick performance and optical transparency of the film while maintaining mechanical strength.
Smart Images
Figure CN122167818A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polypropylene film masterbatch, and particularly to an anti-stick modified BOPP masterbatch and its preparation process. Background Technology
[0002] Biaxially oriented polypropylene (BOPP) film is a high-performance plastic film produced through a special processing technology. Its production technology is primarily based on the combination of the properties of polypropylene raw materials and the biaxial stretching process. Traditional polypropylene films suffer from deficiencies in mechanical strength, transparency, and barrier properties due to their low molecular chain orientation. To improve these properties, biaxial stretching technology was developed industrially. This technology first melt-extrudes polypropylene raw materials into thick sheets or cast sheets, and then mechanically stretches the film stepwise and simultaneously in a temperature range above the glass transition temperature and below the melting point, causing the molecular chains to be highly oriented and orderly arranged along the planar direction. This process improves the tensile strength, rigidity, dimensional stability, and optical transparency of the film, while reducing thickness and improving barrier properties. To further meet diverse application requirements, BOPP film production often incorporates technologies such as blending modification, multilayer co-extrusion, coating, or corona treatment to impart better heat-sealing properties, antistatic properties, printability, or high barrier properties.
[0003] Patent publication number CN118165415A discloses an anti-sticking masterbatch for BOPP film. Its core lies in using a composite of methyl silicone oil and calcium carbonate solution as the key anti-sticking agent, combined with a toughening agent, compatibilizer, antioxidant, and nucleating agent for systematic optimization. This design fully utilizes the surface migration lubrication properties of silicone oil and the microscopic isolation effect of calcium carbonate to form an effective anti-sticking layer on the film surface. The content of each component needs to be precisely proportioned: homopolymer polypropylene as a carrier accounts for 60-70%, the composite anti-sticking agent accounts for 10-20%, of which the ratio of methyl silicone oil to calcium carbonate solution is 1:1 to 1:4, the toughening agent accounts for 10-20%, and the remainder consists of small amounts of compatibilizer, antioxidant, and nucleating agent. The preparation process employs high-speed mixing and twin-screw melt co-extrusion, ensuring uniform dispersion and stable composite of each component by controlling the extrusion temperature, screw speed, and melt pressure.
[0004] Existing technologies commonly use traditional inorganic anti-sticking agents such as silica. However, the control of their particle morphology and size distribution is often not precise enough, making them prone to agglomeration in the masterbatch matrix. This leads to uneven distribution during subsequent film stretching, and excessively high local concentrations may form obvious crystal points or defects, affecting the film's appearance and optical properties. Furthermore, the interfacial compatibility between the carrier resin and the anti-sticking agent is often not effectively improved, resulting in weak bonding. During processing and use, the anti-sticking agent is prone to excessive precipitation or migration from the film surface, causing rapid and unstable degradation of the anti-sticking effect. Summary of the Invention
[0005] The main objective of this invention is to provide an anti-sticking modified BOPP masterbatch and its preparation process, which can effectively solve the problems mentioned in the background art.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An anti-stick modified BOPP masterbatch and its preparation process, comprising the following steps: S1: Stearate and modifier are reacted at 60-120℃ for 0.5-4 hours, and the composite is obtained after drying; S2: First, add polypropylene resin and dispersant and mix, then add the complex prepared in S1, microcapsule foaming agent and antioxidant and mix to obtain a premix; S3: Add the premixed material to a twin-screw extruder for melt extrusion and granulation to obtain BOPP masterbatch.
[0007] Preferably, the preparation steps of the microcapsule foaming agent in step S2 are as follows: A1: Disperse azodicarbonamide in deionized water, add sodium dodecylbenzenesulfonate to form a uniform suspension; A2: Under stirring and pH conditions of 3.5-5.5, a prepolymer solution of melamine and formaldehyde is added to the suspension prepared in A1, and a polycondensation reaction is carried out by heating to form a thermosetting resin shell. A3: After the reaction is complete, the microcapsule foaming agent is obtained by filtration, washing and drying.
[0008] Preferably, in step S1, the stearate is a mixture of aluminum stearate and calcium stearate in a mass ratio of (2.5-5):1; wherein the mass ratio of stearate to modifier is (3-8):1.
[0009] Preferably, the modifier in step S1 is one of vinyl silane, acrylate silane, or glycidyl methacrylate.
[0010] Preferably, in step S2, the mass ratio of polypropylene resin, composite, microcapsule foaming agent, antioxidant, and dispersant is (70-82):(8-12):(4-6.5):(0.5-0.8):(2.5-4).
[0011] Preferably, in step S2, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1 to 2:1; the dispersant is selected from sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.
[0012] Preferably, in step S3, the temperature of the twin-screw extruder in the reaction zone is set to 200-210°C, and the melt pressure in this zone is maintained at 3-8 MPa, with a rotation speed of 200-350 rpm.
[0013] Preferably, in step A2, the temperature is first increased to 60-75℃ for 1-2 hours, and then increased to 85-95℃ for 1-3 hours for curing.
[0014] Preferably, the mass ratio of azodicarbonamide to deionized water in step A1 is 1:(5-20); and the molar ratio of melamine to formaldehyde in step A2 is 1:(0.6-0.83).
[0015] According to another aspect of the present invention, an anti-stick modified BOPP masterbatch prepared by the above preparation method is provided. The masterbatch is used for BOPP film production and is added at a mass ratio of masterbatch to matrix polypropylene of 1:15-1:10. The film is then formed by melt extrusion and biaxial stretching.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In the technical solution of this invention, a composite with regulated interfacial properties is formed by preheating stearate with a specific modifier. When this composite is introduced into the masterbatch system and undergoes subsequent melt processing, it can effectively alleviate the agglomeration tendency of stearate due to its strong polarity, and promote its uniform dispersion in the non-polar polypropylene continuous phase at a finer scale. This provides a structural basis for the uniform and controllable migration of functional components during the subsequent film stretching process, resulting in stable and durable surface anti-stick properties.
[0017] 2. In the technical solution of this invention, a microcapsule structure prepared by in-situ polycondensation, with a thermosetting resin as the outer shell encapsulating the foaming agent, works synergistically with stearate complex modification technology to jointly regulate the functional release of the masterbatch. The core-shell structure of the microcapsules correlates the decomposition temperature of the foaming agent with the rupture conditions of the outer shell, making its decomposition behavior time-matched with the key stages of the biaxial stretching process. When the film is heated and stretched, the microcapsule shell undergoes controlled rupture under synergistic action, and the released gas forms a large number of submicron-scale isolated pores in the polymer matrix that has been initially oriented but not yet fully crystallized. These internal pores and the microscopic protrusions they induce on the surface coexist physically with the low-energy crystalline layer formed by surface migration, synergistically working from two dimensions: reducing the effective contact area and lowering the surface energy, which may improve the uniformity of the anti-adhesion effect of the film.
[0018] 3. In the preparation of the microcapsule foaming agent, this invention employs an optimized segmented polymerization process to achieve two-stage control of shell formation. In the low-temperature stage, melamine-formaldehyde prepolymer is gradually deposited on the surface of azodicarbonamide particles at a low reaction rate to form a uniform primary shell. In the high-temperature curing stage, the primary shell undergoes further cross-linking reaction, forming a three-dimensional network structure between molecular chains. This transforms the shell from a linear or branched structure into a highly cross-linked thermosetting structure, increasing its density. The controllable shear melt blending process, through the synergistic regulation of temperature, pressure, and shear rate, ensures that the thermal load on the microcapsules during melt extrusion is below their rupture threshold. The submicron-scale pores formed during biaxial stretching are uniform in size and distribution. Together with the surface lubricating layer of the modified composite, appropriate shearing disperses the modified stearate composite at the micron scale in the polypropylene melt, forming a uniform anti-sticking functional phase. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the preparation process of the anti-sticking modified BOPP masterbatch of the present invention. Detailed Implementation
[0020] The endpoints and any values of the ranges disclosed in this invention are not limited to the precise range thresholds, and these range thresholds should be understood to include values close to these range thresholds. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.
[0021] The following describes in detail, with reference to the accompanying drawings, an anti-sticking modified BOPP masterbatch and its preparation process provided in the embodiments of this specification.
[0022] like Figure 1 As shown, the preparation process of an anti-sticking modified BOPP masterbatch and its preparation technology is as follows, and the specific implementation steps are as follows.
[0023] Preparation Example 1 A1: Accurately weigh 50g of azodicarbonamide and add it to 1000mL of deionized water. Turn on the stirrer and set it to 300rpm for 10min to initially disperse the azodicarbonamide. Then add 8g of sodium dodecylbenzenesulfonate and continue stirring for 30min to form a uniform and stable suspension with no obvious precipitation or stratification.
[0024] A2: Adjust the pH of the above suspension to 4.0 with dilute hydrochloric acid, keep the stirring speed constant, place the suspension in a constant temperature water bath, and slowly heat it to 65℃; accurately weigh 30g of melamine and 80g of formaldehyde, prepare a melamine-formaldehyde prepolymer solution in advance, and slowly add the prepolymer solution to the suspension at a rate of 2mL / min. After the addition is complete, keep the temperature at 65℃ for 1.5 hours to carry out preliminary polycondensation; then raise the water bath temperature to 90℃ and keep the temperature at 90℃ for 2 hours to solidify, so that the prepolymer is fully deposited and solidified on the surface of the azodicarbonamide particles to form a dense thermosetting melamine-formaldehyde resin shell.
[0025] A3: After the reaction is complete, turn off the stirrer and the constant temperature water bath, cool the reaction system to room temperature, and use a vacuum filtration device to filter and collect the filter cake; wash the filter cake repeatedly with deionized water 4 times, each time using 500 mL, until the pH of the washing solution is 7.0, to remove the residual sodium dodecylbenzenesulfonate and unreacted monomers on the surface of the filter cake; put the washed filter cake into a forced-air drying oven and dry it at 90℃ for 3 hours. After drying, pulverize it to a particle size of less than 50 μm to obtain the microcapsule foaming agent, which is then sealed and stored for later use.
[0026] Preparation Example 2 A1: Accurately weigh 45g of azodicarbonamide and add it to 900mL of deionized water. Turn on the stirrer and set it to 280rpm for 15min to initially disperse the azodicarbonamide. Then add 6g of sodium dodecylbenzenesulfonate and continue stirring for 40min to form a uniform and stable suspension with no obvious precipitation or stratification.
[0027] A2: Adjust the pH of the above suspension to 3.5 with dilute hydrochloric acid, keep the stirring speed constant, set the suspension to 280 rpm and place it in a constant temperature water bath, slowly raise the temperature to 60℃; accurately weigh 25g of melamine and 65g of formaldehyde, prepare a melamine-formaldehyde prepolymer solution in advance, slowly add the prepolymer solution dropwise to the suspension at a rate of 1.5mL / min, after the addition is complete, keep the temperature at 60℃ for 2 hours to carry out preliminary polycondensation; then raise the water bath temperature to 85℃ and keep the temperature at 85℃ for 3 hours to solidify, so that the prepolymer is fully deposited and solidified on the surface of the azodicarbonamide particles to form a dense thermosetting melamine-formaldehyde resin shell.
[0028] A3: After the reaction is complete, turn off the stirrer and the constant temperature water bath, cool the reaction system to room temperature, and use a vacuum filtration device to filter through a 100-mesh filter to collect the filter cake. Wash the filter cake repeatedly with deionized water 3 times, each time using 400 mL, until the pH of the washing solution is 7.0 to remove residual sodium dodecylbenzenesulfonate and unreacted monomers from the surface of the filter cake. Place the washed filter cake in a forced-air drying oven and dry it at 80°C for 4 hours. After drying, pulverize it to a particle size of less than 50 μm to obtain the microcapsule foaming agent, which should be sealed and stored for later use.
[0029] Preparation Example 3 A1: Accurately weigh 55g of azodicarbonamide and add it to 1100mL of deionized water. Turn on the stirrer and set the speed to 320rpm for 8min to initially disperse the azodicarbonamide. Then add 9g of sodium dodecylbenzenesulfonate and continue stirring for 25min to form a uniform and stable suspension with no obvious precipitation or stratification.
[0030] A2: Adjust the pH of the above suspension to 5.5 with dilute hydrochloric acid, keep the stirring speed constant, set the suspension to 320 rpm and place it in a constant temperature water bath, slowly raise the temperature to 75°C; accurately weigh 35g of melamine and 100g of formaldehyde, prepare a melamine-formaldehyde prepolymer solution in advance, slowly add the prepolymer solution to the suspension at a rate of 2.5mL / min, after the addition is complete, keep the temperature at 75°C for 1 hour to carry out preliminary polycondensation; then raise the water bath temperature to 95°C and keep the temperature at 95°C for 1 hour to solidify, so that the prepolymer is fully deposited and solidified on the surface of the azodicarbonamide particles to form a dense thermosetting melamine-formaldehyde resin shell.
[0031] A3: After the reaction is complete, turn off the stirrer and the constant temperature water bath, cool the reaction system to room temperature, and use a vacuum filtration device to filter through a 200-mesh filter to collect the filter cake. Wash the filter cake repeatedly with deionized water 5 times, each time using 600 mL, until the pH of the washing solution is 7.0 to remove residual sodium dodecylbenzenesulfonate and unreacted monomers from the surface of the filter cake. Place the washed filter cake in a forced-air drying oven and dry it at 100℃ for 2 hours. After drying, pulverize it to a particle size of less than 50 μm to obtain the microcapsule foaming agent, which is then sealed and stored for later use.
[0032] Example 1 An anti-sticking modified BOPP masterbatch and its preparation process are disclosed, with the specific implementation steps as follows: S1: Accurately weigh the stearate mixture, including 40g of aluminum stearate and 10g of calcium stearate in a mass ratio of 4:1, and add it to a 200mL three-necked flask. Then add 7.5g of glycidyl methacrylate, making the mass ratio of stearate to modifier 6.7:1. Place the three-necked flask in an oil bath, turn on the stirring and reflux condenser at 200rpm, and control the oil bath temperature at 90℃ for 2 hours. After the reaction is complete, place the product in a forced-air drying oven and dry it at 85℃ for 2.5 hours to remove moisture, obtaining the modified stearate complex for later use.
[0033] S2: Accurately weigh 760g of polypropylene resin and 30g of sodium dodecyl sulfate, add them to a high-speed mixer, turn on the mixer and set the speed to 1500rpm, mix for 15min to ensure that the polypropylene resin and dispersant are uniformly mixed; then add 100g of the modified stearate complex prepared above, 55g of the microcapsule foaming agent prepared in Preparation Example 1, and 7g of antioxidant mixture, wherein the mass ratio of antioxidant 1010 to antioxidant 168 is 1.5:1, continue mixing for 25min, and control the temperature inside the mixer to not exceed 50℃ during the mixing process to avoid softening of the polypropylene resin, so as to obtain a uniform premix, and the premix has no obvious agglomeration or particle aggregation.
[0034] S3: Add the above premix to a twin-screw extruder and set the temperature zones of the twin-screw extruder as follows: feed zone 170℃, melting zone 190℃, reaction zone 205℃, and die head zone 200℃. The melt pressure in the reaction zone is maintained at 5MPa, and the screw speed is 280rpm. The premix is melted, mixed, and extruded in the twin-screw extruder. The extrudate is then water-cooled at 25℃, pelletized by a pelletizer to a particle size of 2-3mm, and dried with hot air at 70℃ for 1.5 hours to obtain the non-stick modified BOPP masterbatch.
[0035] Example 2 An anti-sticking modified BOPP masterbatch and its preparation process are disclosed, with the specific implementation steps as follows: S1: Accurately weigh the stearate mixture, including 25g of aluminum stearate and 10g of calcium stearate, and add it to a 200mL three-necked flask. Then add 6.25g of vinylsilane. The mass ratio of stearate to modifier is 6:1. Place the three-necked flask in an oil bath, turn on the stirring and reflux condenser at 180rpm, control the oil bath temperature at 60℃, and react at a constant temperature for 4 hours. After the reaction is completed, put the product into a forced-air drying oven and dry it at 80℃ for 3 hours to remove moisture, and obtain the modified stearate complex for later use.
[0036] S2: Accurately weigh 700g of polypropylene resin and 25g of sodium dodecylbenzenesulfonate, add them to a high-speed mixer, turn on the mixer at 1200rpm, and mix for 20min to ensure that the polypropylene resin and dispersant are uniformly mixed; then add 80g of the modified stearate complex prepared above, 40g of the microcapsule foaming agent prepared in Preparation Example 2, and 5g of antioxidant mixture, wherein the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1, and continue mixing for 30min. During the mixing process, control the temperature inside the mixer to not exceed 50℃ to avoid softening of the polypropylene resin, and obtain a uniform premix. The premix has no obvious agglomeration or particle aggregation.
[0037] S3: Add the above premix to a twin-screw extruder and set the temperature zones of the twin-screw extruder as follows: feed zone 165℃, melting zone 185℃, reaction zone 200℃, and die head zone 195℃. The melt pressure in the reaction zone is maintained at 3MPa, and the screw speed is 200rpm. The premix is melted, mixed, and extruded by the twin-screw extruder. The extrudate is water-cooled at 20℃, pelletized by a pelletizer to a particle size of 2-3mm, and dried with hot air at 65℃ for 2 hours to obtain anti-sticking modified BOPP masterbatch.
[0038] Example 3 An anti-sticking modified BOPP masterbatch and its preparation process are disclosed, with the specific implementation steps as follows: S1: Accurately weigh the stearate mixture, including 50g of aluminum stearate and 10g of calcium stearate in a mass ratio of 5:1, and add it to a 200mL three-necked flask. Then add 8g of acrylate-type silane, making the mass ratio of stearate to modifier 7.5:1. Place the three-necked flask in an oil bath, turn on the stirring and reflux condenser at 220rpm, control the oil bath temperature at 120℃, and react at a constant temperature for 0.5 hours. After the reaction is complete, place the product in a forced-air drying oven and dry it at 90℃ for 2 hours to remove moisture, obtaining the modified stearate complex for later use.
[0039] S2: Accurately weigh 820g of polypropylene resin and 40g of sodium dodecyl sulfate, add them to a high-speed mixer, turn on the mixer at 1800rpm, and mix for 10min to ensure that the polypropylene resin and dispersant are uniformly mixed; then add 120g of the modified stearate complex prepared above, 65g of the microcapsule foaming agent prepared in Preparation Example 3, and 8g of antioxidant mixture, wherein the mass ratio of antioxidant 1010 to antioxidant 168 is 2:1, and continue mixing for 20min. During the mixing process, control the temperature inside the mixer to not exceed 50℃ to avoid softening of the polypropylene resin, and obtain a uniform premix. The premix has no obvious agglomeration or particle aggregation.
[0040] S3: Add the above premix to a twin-screw extruder and set the temperature zones of the twin-screw extruder as follows: feed zone 175℃, melting zone 195℃, reaction zone 210℃, and die head zone 205℃. The melt pressure in the reaction zone is maintained at 8MPa, and the screw speed is 350rpm. The premix is melted, mixed, and extruded by the twin-screw extruder. The extrudate is water-cooled at 30℃, pelletized by a pelletizer to a particle size of 2-3mm, and dried with hot air at 75℃ for 1 hour to obtain anti-sticking modified BOPP masterbatch.
[0041] Comparative Example 1 In step S1, no modifiers or stearates are added; only aluminum stearate is used. The remaining steps are the same as in Example 1.
[0042] Comparative Example 2 In step S1, the modified stearate complex is not prepared; instead, the conventional anti-sticking agent silica is used. The remaining steps are the same as in Example 1.
[0043] Comparative Example 3 No microcapsule foaming agent was added, and step A2 was not performed with segmented heating; the temperature was directly raised to 90°C and reacted for 3.5 hours. The remaining steps were the same as in Example 1.
[0044] Comparative Example 4 Without adding microcapsule foaming agent, pure azodicarbonamide was used directly, and the remaining steps were the same as in Example 1.
[0045] Comparative Example 5 Except for step S3, where the temperature of the twin-screw extruder reaction section is changed to 185°C and the screw speed is changed to 180 rpm, the other steps are the same as in Example 1.
[0046] The following performance tests were conducted on the anti-sticking modified BOPP masterbatches prepared in Examples 1-3 and Comparative Examples 1-5: 1. Anti-stick performance test Referring to GB / T10006-1988 "Determination of Coefficient of Friction of Plastic Films and Sheets", the friction coefficient meter was adjusted, the test speed was set to 100 mm / min, the test load to 200 g, and the contact area to 20 mm × 30 mm. Test samples from the examples and comparative examples were selected, the surface of the samples was wiped with anhydrous ethanol, and allowed to air dry naturally to avoid residual ethanol affecting the test. The samples were fixed on the lower sample stage of the friction coefficient meter, and a blank BOPP film of the same specification was fixed on the upper sample stage.
[0047] Start the instrument and measure the static and dynamic friction coefficients between the sample and the blank film. Test three different locations for each sample and record the data. Calculate the average value of the static and dynamic friction coefficients. The lower the friction coefficient, the better the anti-sticking performance.
[0048] 2. Optical performance testing Referring to GB / T2410-2008 "Determination of transmittance and haze of transparent plastics", the transmittance and haze meter was calibrated, with the test wavelength set to 550 nm. Air was used as a blank control for blank calibration, and the transmittance calibration was set to 100%. Test samples from the examples and comparative examples were selected, and the surface of the samples was wiped with a lint-free cloth to remove dust and impurities, avoiding scratches that could affect the test. The samples were then placed flat in the instrument's test slot, ensuring that the samples completely covered the test window without bubbles or wrinkles.
[0049] Start the instrument and measure the transmittance of each sample. Test each sample at 3 different locations and record the data. Test 3 samples in each group and calculate the average transmittance. The higher the transmittance, the better the optical performance of the film and the absence of obvious crystal points or defects.
[0050] 3. Mechanical property testing Referring to GB / T13542.2-2009 "Plastic Films for Electrical Purposes - Part 2: Polyester Films", cut test pieces for each group of samples to make dumbbell-shaped specimens (stretch length 25mm, width 4mm, thickness 0.02mm). Prepare 10 specimens for each group, remove specimens with edge damage or defects, and retain 8 valid specimens.
[0051] Calibrate the electronic universal testing machine, set the tensile speed to 50 mm / min, and the tensile load range to 0-50 N. Fix both ends of the dumbbell-shaped specimen to the clamps of the testing machine, ensuring that the specimen is flat, without tension or twisting, and the clamp spacing is 20 mm.
[0052] Start the instrument and perform tensile tests until the specimen breaks. Record the ratio of the maximum load at fracture to the cross-sectional area of the specimen for each sample. Test 8 valid specimens for each group of samples, remove the maximum and minimum values, and calculate the average tensile strength of the remaining 6 specimens. The higher the tensile strength, the better the mechanical properties of the film. The specific results are shown in Table 1.
[0053] Table 1: Performance Test Results of Anti-stick Modified BOPP Masterbatch As shown in Table 1, the static friction coefficients of the example group were between 0.10 and 0.12, and the dynamic friction coefficients were between 0.07 and 0.09, both exhibiting excellent anti-stick properties. The synergistic effect of the modified stearate composite and the microcapsule foaming agent, and the improved compatibility of the stearate with the polypropylene matrix after modification with silane or acrylate, prevented local agglomeration. During biaxial stretching, the microcapsule foaming agent released gas in a controlled manner, forming a uniform micron-scale protrusion structure, reducing the interlayer contact area of the film.
[0054] The friction coefficients of Comparative Examples 1 and 2 increased significantly, indicating that the unmodified anti-sticking agent was prone to agglomeration and uneven distribution, which led to a decrease in the anti-sticking effect. The anti-sticking performance of Comparative Examples 3 and 4 deteriorated further because the foaming agent shell was incomplete or missing, resulting in premature gas release or uneven bubble size, which prevented the formation of an effective surface topology. The friction coefficient of Comparative Example 5 was higher than that of the Example Group because the melt was not mixed sufficiently and the dispersion was uneven.
[0055] The light transmittance of the example group is 90-92%, and the optical performance is excellent. Due to the controllable size of the micro-protrusions formed by the microcapsule foaming agent, strong scattering of light is avoided.
[0056] Comparative Examples 2 and 4 had the lowest light transmittance of 78-80%, due to significant light scattering caused by inorganic particle agglomeration or excessively large bubbles; Comparative Examples 1 and 5 had lower light transmittance than the Example, indicating that poor interface compatibility or process out-of-control could lead to an increase in defects; Comparative Example 3 had a light transmittance of 82%, which was better than Comparative Example 4, but still lower than the Example, highlighting the crucial role of staged heating in maintaining shell integrity.
[0057] The tensile strength of the example group was 43.0-46.0 MPa: the mechanical properties were stable, and the uniform dispersion of the microencapsulated foaming agent and modified stearate avoided stress concentration points. The strength of Example 3, 46.0 MPa, may be related to its stearate ratio (5:1) and the enhanced interfacial bonding force caused by the high-temperature short-time reaction.
[0058] Comparative Examples 2 and 4 showed the lowest strength because agglomerates or large bubbles became weak points; Comparative Examples 1 and 3 showed improved strength, but were still lower than the examples, indicating that interface modification can effectively transfer stress; Comparative Example 5 showed strength close to the examples, indicating that process optimization has a significant impact on mechanical properties.
[0059] In summary, this invention utilizes glycidyl methacrylate / silane coupling agent to surface-modify stearate, synergistically combining it with azodicarbonamide foaming agent microencapsulated in melamine-formaldehyde resin, and employing optimized segmented polymerization and controlled shear melt blending processes to prepare an anti-stick modified BOPP masterbatch with excellent surface lubricity, high optical transparency, and good mechanical strength. This masterbatch significantly improves the anti-stick properties of BOPP films while maintaining their high light transmittance and mechanical integrity.
[0060] In the description of this specification, the reference to terms such as "embodiment," "various embodiments," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or preparation example is included in at least one embodiment of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.
[0061] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. An anti-sticking modified BOPP masterbatch and its preparation process, characterized in that, Includes the following steps: S1: Stearate and modifier are reacted at 60-120℃ for 0.5-4 hours, and the composite is obtained after drying; S2: First, add polypropylene resin and dispersant and mix, then add the complex prepared in S1, microcapsule foaming agent and antioxidant and mix to obtain a premix; S3: Add the premixed material to a twin-screw extruder for melt extrusion and granulation to obtain BOPP masterbatch.
2. The process for preparing anti-sticking modified BOPP masterbatch according to claim 1, characterized in that, The preparation steps of the microcapsule foaming agent in step S2 are as follows: A1: Disperse azodicarbonamide in deionized water, add sodium dodecylbenzenesulfonate to form a uniform suspension; A2: Under stirring and pH conditions of 3.5-5.5, a prepolymer solution of melamine and formaldehyde is added to the suspension prepared in A1, and a polycondensation reaction is carried out by heating to form a thermosetting resin shell. A3: After the reaction is complete, the microcapsule foaming agent is obtained by filtration, washing and drying.
3. The process for preparing anti-sticking modified BOPP masterbatch according to claim 1, characterized in that, In step S1, the stearate is a mixture of aluminum stearate and calcium stearate in a mass ratio of (2.5-5):1; wherein the mass ratio of stearate to modifier is (3-8):
1.
4. The process for preparing anti-sticking modified BOPP masterbatch according to claim 1, characterized in that, The modifier in step S1 is one of vinyl silane, acrylate silane, or glycidyl methacrylate.
5. The process for preparing anti-sticking modified BOPP masterbatch according to claim 1, characterized in that, In step S2, the mass ratio of polypropylene resin, composite, microcapsule foaming agent, antioxidant, and dispersant is (70-82):(8-12):(4-6.5):(0.5-0.8):(2.5-4).
6. The process for preparing anti-stick modified BOPP masterbatch according to claim 1, characterized in that, In step S2, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1 to 2:1; the dispersant is selected from sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.
7. The process for preparing anti-sticking modified BOPP masterbatch according to claim 1, characterized in that, In step S3, the temperature of the twin-screw extruder in the reaction zone is set to 200-210℃, and the melt pressure in this zone is maintained at 3-8MPa, with a rotation speed of 200-350rpm.
8. The process for preparing anti-sticking modified BOPP masterbatch according to claim 2, characterized in that, The heating in step A2 adopts a segmented polymerization process, first reacting at 60-75℃ for 1-2 hours, and then heating to 85-95℃ for curing for 1-3 hours.
9. The preparation method according to claim 2, characterized in that, In step A1, the mass ratio of azodicarbonamide to deionized water is 1:(5-20); in step A2, the molar ratio of melamine to formaldehyde is 1:(0.6-0.83).
10. A non-stick modified BOPP masterbatch prepared by the preparation method according to any one of claims 1-9, characterized in that, This masterbatch is used in the production of BOPP film. It is added at a mass ratio of masterbatch to polypropylene matrix of 1:15-1:10, and the film is made by melt extrusion and biaxial stretching.