A non-stick silica masterbatch and a method for its preparation

Abstract

This invention relates to the field of thin films, and particularly to a silica anti-adhesion masterbatch resistant to peeling and its preparation method. The anti-adhesion masterbatch comprises homopolymer polypropylene, 2-10 wt% modified silica, 1-10 wt% SEBS-g-MAH, and 0.1-0.6 wt% antioxidant. The modified silica is obtained by modifying silica with a styrene-based diaminosilane coupling agent, wherein the amount of silane coupling agent used is 1-5% of the mass fraction of silica. The anti-adhesion masterbatch of this invention, on the one hand, improves the bonding strength between the modified silica and the anti-adhesion masterbatch carrier resin and the film surface matrix resin polypropylene; on the other hand, it also helps to improve the thermal stability and mechanical strength of the masterbatch carrier and matrix resin polypropylene resin system, making the prepared film less prone to softening and plasticizing under high-speed operation. The synergistic effect further reduces the likelihood of silica particles peeling off due to the strong friction on the film surface under high-speed operation.

Description

Technical Field

[0001] This invention relates to the field of thin films, and in particular to a silica anti-adhesion masterbatch resistant to shedding and its preparation method. Background Technology

[0002] Due to its unique physical structure and excellent anti-blocking properties, silica has become the most widely used and technologically mature core component of anti-blocking masterbatches in the thin film field. Silica-based anti-blocking masterbatches typically consist of silica and a carrier (homopolymer polypropylene or copolymer polypropylene). During thin film preparation, silica is dispersed into the matrix resin on the film surface with the help of the carrier resin. Under the action of mechanical stress and interfacial tension difference, the high-melting-point and non-stretchable silica particles migrate to the film surface. Some are embedded in the film, while others are exposed outside, forming microscopic protrusions on the film surface. This is the source of the anti-blocking function.

[0003] However, because silica is rich in silanol groups (Si-OH), making it a highly polar and hydrophilic substance, while the BOPP film's surface matrix resin, polypropylene, contains only C-C and CH bonds and is a non-polar and hydrophobic substance, when the two are directly mixed, silica tends to agglomerate, resulting in extremely weak interfacial bonding with polypropylene. Therefore, current silica-based anti-adhesion masterbatches typically utilize silane coupling agents (such as KH550, KH560, KH570, and KH792) to modify the silica.

[0004] The general formula for traditional silane coupling agents is R n SiX （4-n） After Si-X is converted to Si-OH through hydrolysis, the Si-OH on the silane coupling agent will dehydrate and condense with the Si-OH on the surface of silicon dioxide to form a strong siloxane bond (Si-O-Si). Therefore, in silica modified with silane coupling agents, the Si-OH on the surface is transformed into the organic functional group R of the silane coupling agent. On the one hand, this organic functional group R can reduce the surface energy of silica, improve the compatibility between silica and polypropylene, reduce the agglomeration of silica in the anti-adhesion masterbatch carrier resin, and allow silica particles to be dispersed in the anti-adhesion masterbatch carrier as independently as possible. This independent dispersion helps ensure that silica has a complete surface coating layer (i.e., coated by the anti-adhesion masterbatch carrier resin) after being mixed into the film surface matrix resin, so that silica exists in the film surface matrix resin in the form of migratory particles. Then, during the film preparation process, the anti-adhesion masterbatch carrier resin can be mixed evenly with the film surface matrix resin, thereby forming more uniform micro-protrusions on the film surface. On the other hand, this organic functional group R can also form a certain entanglement with olefin polymer molecular chain segments, so that it generates a certain binding force with polypropylene.

[0005] However, when using existing silane coupling agent-modified silica anti-sticking masterbatch to prepare BOPP film, during downstream slitting, rewinding, or printing processes, the modified silica, which is distributed on the film surface in an anchoring protrusion pattern, will detach due to the strong friction and shear force on the film surface under high-speed operation, because the bonding force with the polypropylene resin is less than the external friction and shear force experienced by the film. This detachment accumulates on the pressure rollers or traction rollers, affecting film rewinding, slitting, or printing, requiring machine shutdown for cleaning, which increases labor costs and reduces equipment uptime. Summary of the Invention

[0006] Based on this, the purpose of this invention is to provide a silica anti-adhesion masterbatch resistant to peeling and its preparation method. Under the synergistic effect of modified silica and the interfacial heat stabilizer SEBS-g-MAH, on the one hand, the bonding strength between modified silica and anti-adhesion masterbatch carrier resin and film surface matrix resin polypropylene is improved, and on the other hand, it is also beneficial to improve the thermal stability and mechanical strength of the masterbatch carrier and film surface matrix resin polypropylene resin system, so that the prepared film is not easy to soften or plasticize under high speed operation. Under the synergistic effect, silica particles are less likely to peel off due to the strong friction and strong shear force on the film surface under high speed operation.

[0007] The technical solution of the present invention is achieved in the following ways:

[0008] A silica-resistant anti-sticking masterbatch for detachment includes homopolymer polypropylene, 2-10 wt% modified silica, 1-10 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, and 0.1-0.6 wt% antioxidant; the modified silica is obtained by modifying silica with a styrene-based diaminosilane coupling agent, wherein the amount of the styrene-based diaminosilane coupling agent used in the modified silica is 1-5% of the mass fraction of the silica.

[0009] Through extensive practical experience, the inventors discovered that existing silane coupling agent-modified silica anti-blocking masterbatches have insufficient bonding strength with polypropylene resin, mainly due to two reasons: First, the organic functional groups of existing silane coupling agents mainly form physical entanglements with polypropylene through interpenetration, entanglement, and van der Waals forces with the polypropylene molecular chains, dispersing them in the polypropylene matrix resin of the film surface layer. However, these effects are all mechanically interlocked physical effects with low bonding strength. At low speeds and room temperatures, this bonding is stable enough, but once subjected to strong shear forces from high-speed operation, these physical entanglements will be easily pulled apart and slip, causing silica particles distributed on the film surface layer in the form of anchored protrusions to fall off from the polypropylene matrix resin of the film surface layer.

[0010] Secondly, during downstream slitting, rewinding, or printing processes, the frictional heat generated by high-speed operation can cause the polypropylene matrix on the film surface to soften, plasticize, or even flow, which greatly increases the activity of the polypropylene molecular chains. As a result, the entangled chain segments that originally surrounded the silica particles will quickly loosen and untangle.

[0011] The anti-adhesion masterbatch of the present invention achieves a synergistic effect between modified silica obtained by modifying silica with a styrene-based diaminosilane coupling agent and the interfacial heat stabilizer maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer (SEBS-g-MAH). This enhances the bonding force between the silica particles embedded in the polypropylene film surface matrix and the matrix, making the silica particle-matrix interfacial bonding force much greater than the external friction and shear forces that the film actually withstands during use. This results in extremely low silica shedding and improves the thermal stability and mechanical properties of the masterbatch carrier and the polypropylene resin system of the film surface matrix. It effectively reduces the possibility of silica particles being pulled out and detached under high-speed, strong shear forces due to the physical entanglement points being pulled apart and slipping.

[0012] Specifically, regarding the improvement of the bonding force between silica particles and polypropylene: On the one hand, this invention utilizes the unique structure of styrene-based diaminosilane coupling agents: simultaneously containing vinyl and amino groups, integrating double bonds, secondary amines, and aromatic systems. The secondary amine structure endows the coupling agent with the ability to chemically bond with the MAH groups in SEBS-g-MAH, while the aromatic system exhibits excellent thermal stability. The presence of benzene rings at the interface between silica and the polypropylene matrix introduces numerous rigid aromatic physical crosslinking sites. These sites, through strong steric hindrance with the polypropylene molecular chains, construct a dense three-dimensional physical constraint network, effectively suppressing the slippage and untangling of the polypropylene molecular chains under stress, thereby greatly enhancing the bonding strength at the silica particle embedding segment-matrix interface.

[0013] On the other hand, during the extrusion preparation of the anti-adhesion masterbatch, some unreacted amino functional groups in the styrene-based diaminosilane coupling agent can react with the anhydride groups of the interfacial heat stabilizer SEBS-g-MAH to form strong imide bonds (covalent bonds), tightly linking the modified silica with SEBS-g-MAH. This covalent bond chemical bonding creates a stronger coating of the silica particles. Furthermore, the ethylene / butene (EB) blocks on the SEBS-g-MAH main chain act as flexible anchoring segments, enabling deeper physical entanglement and interpenetration with the molecular chains of the polypropylene carrier resin. Thus, the modified silica particles are firmly connected and locked within the polypropylene resin through the synergistic effect of the chemical linkage of SEBS-g-MAH and the aforementioned physical entanglement.

[0014] Overall, the above two aspects improve upon the conventional modified silica's reliance on physical molecular chain entanglement to ensure bonding with polypropylene resin, through the combined effects of covalent bonds, strong steric hindrance, and molecular chain entanglement. The modified silica of this invention can generate at least 2-3 bonding sites with the surface matrix resin polypropylene, resulting in a tighter bond between the modified silica and polypropylene resin. This effectively reduces the possibility of silica particles being pulled out due to the physical entanglement points being pulled apart or slipping under high-speed, strong shear forces.

[0015] Improvements in the heat resistance and mechanical properties of the masterbatch carrier and film surface matrix resin polypropylene resin system: On the one hand, the styrene-based diaminosilane coupling agent in the modified silica introduces a benzene ring with high thermal stability into the system, which is beneficial to improving the thermal stability of the polypropylene resin system.

[0016] On the other hand, SEBS-g-MAH possesses excellent thermal stability and can enhance the strength of the blend system. Specifically, the polystyrene (PS) segments in the SEBS molecule can form physically cross-linked microdomains, giving the material itself high strength at room temperature; the ethylene-butene (EB) segments in the SEBS molecule undergo complete hydrogenation, saturating the carbon-carbon double bonds and eliminating the weak links that are prone to thermal oxidative degradation, which is the fundamental reason for the high thermal stability of SEBS-g-MAH; after the MAH group chemically bonds with the amino group of the styrene-based diaminosilane coupling agent, it can significantly improve the microstructure of the modified silica and polypropylene blend system, reduce internal defects, and thus improve the thermal stability and mechanical properties of the blend system.

[0017] In summary, the present invention, through the synergistic effect of modified silica and the interfacial heat stabilizer SEBS-g-MAH, not only forms chemical covalent bonds, strong steric hindrance, and physical entanglement of molecular chains among modified silica, SEBS-g-MAH, and polypropylene, effectively restricting the movement of polypropylene molecular chains, but also improves the thermal stability of the polypropylene resin system as the matrix resin of the film surface when used to prepare films, inhibits the softening and plasticizing of the polypropylene matrix resin under frictional heat, and synergistically reduces the possibility of silica particles falling off under high shear force.

[0018] Based on this, the present invention limits the content of modified silica in the anti-adhesion masterbatch to 2~10wt%. If the content of modified silica is less than 2wt%, the number of micro protrusions formed by silica particles on the surface of the film prepared by it will be insufficient, the contact area between film layers will be too large, the surface friction coefficient will be high, and the film will easily stick together. In severe cases, problems such as difficulty in separation, tearing with a sound, or film deformation may occur, directly affecting the smoothness of downstream high-speed packaging and unwinding processes. If the amount of modified silica added is greater than 10wt%, the number of micro protrusions formed by silica particles on the surface of the film prepared by it will be too large, and the particles will be densely packed. This oversaturated distribution will significantly reduce the height difference between adjacent protrusions, and the tops of many protrusions will be almost on the same plane. The overall micro-profile of the film will tend to be flat. In this case, the contact form between film layers will degenerate from the ideal "point contact" to "surface contact". The actual contact area will not only not decrease, but will increase significantly due to the tight adhesion of the flat surface, directly leading to an increase in the surface friction coefficient and a decrease in opening performance.

[0019] The present invention further specifies that the treatment amount of styrene-based diaminosilane coupling agent in the preparation process of modified silica is controlled to be 1-5% of the mass fraction of silica. The treatment amount refers to the amount (mass) of styrene-based diaminosilane coupling agent added to the silica system each time (for modification treatment), that is, the amount of styrene-based diaminosilane coupling agent added to the silica system each time for modification treatment is controlled to be between 1-5% of the mass of silica. If the amount of styrene-based diaminosilane coupling agent used is less than 1% of the mass fraction of silica, the coupling agent content is too low, and only a small portion of the coupling agent reacts with the silica. This results in unsatisfactory silica modification, failure to significantly improve hydrophobic properties, and the presence of unreacted silanol groups on the surface, affecting the compatibility between the modified silica and the polypropylene resin. Conversely, if the amount of styrene-based diaminosilane coupling agent used is greater than 5% of the mass fraction of silica, the surface grafting of the coupling agent onto the silica has reached its limit. Excess coupling agent will undergo self-polymerization reactions on the silica surface, such as silane condensation and vinyl polymerization, forming a multilayered coating structure. This multilayered coating structure embeds the styrene group action sites of the styrene-based diaminosilane coupling agent internally, thereby shielding these sites from the originally efficient steric anchoring effect between the polypropylene molecular chains and forming a weak boundary layer with low cohesive strength at the interface. Ultimately, this leads to a significant decrease in the bonding force between the modified silica and the carrier resin, polypropylene.

[0020] This invention also limits the content of maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer to 1~10wt%. As an interfacial heat stabilizer, if the amount of SEBS-g-MAH added is less than 1wt%, the number of anhydride groups that can chemically combine with the amino groups in the styrene-based diaminosilane coupling agent is small, and it is impossible to form sufficient and strong chemical covalent bonds with the modified silica. This is not conducive to the interfacial bonding force between silica particles and polypropylene resin. Silica particles are very easy to re-agglomerate during melt blending and cannot achieve uniform dispersion. If the amount of SEBS-g-MAH added is greater than 10wt%, the number of MAH in the anti-adhesion masterbatch system is too large. At high temperature, the MAH groups are easy to hydrolyze and undergo intermolecular dehydration, causing local chemical crosslinking between SEBS-g-MAH molecular chains. At the same time, excessive MAH will also react excessively with the amino groups on the coupling agent, forming an excessively tight and crosslinked SEBS coating layer on the silica surface. This coating not only shields the rigid sites of the styrene groups of the coupling agent, but also restricts the physical entanglement ability of the EB segments, thereby weakening the effective bonding force between the silica particles and the polypropylene matrix, and increasing the risk of silica particles falling off.

[0021] Furthermore, the styrene-based diaminosilane coupling agent is 3-(N-styrene-methyl-2-aminoethylamino)propyltrimethoxysilane.

[0022] Furthermore, the styrene-based bisaminosilane coupling agent is obtained by a nucleophilic substitution reaction between the terminal amino group of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and the chloromethyl group of p-chloromethylstyrene to form a secondary amine.

[0023] Furthermore, the preparation method of the modified silica includes the following steps: adding a styrene-based diaminosilane coupling agent ethanol solution dropwise into a silica n-butanol dispersion with a pH of 2-4 at 100°C, reacting for 6 hours, centrifuging, washing, and drying to obtain the styrene-based diaminosilane coupling agent.

[0024] Furthermore, the particle size D50 of the modified silica is 3~7μm. If the modified silica D50 is less than 3μm, the microscopic protrusions formed on the film surface by the small-sized modified silica are too low in height. The low protrusions are difficult to form an effective support gap between adjacent film layers, resulting in the film being tightly adhered and difficult to unwind. If the modified silica D50 is greater than 7μm, the large-diameter particles are easy to scrape the film surface during the film stretching process, resulting in damage to the film appearance. The excessively large particle size will also reduce the interfacial compatibility with polypropylene, resulting in insufficient bonding force and detachment, affecting subsequent processing.

[0025] Furthermore, the maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer is selected from one or more of Kraton FG1901G, Kraton FG1924, Taipol 7131, and Zhiyuan FG03.

[0026] Furthermore, the homopolymer polypropylene has a melting point of 160~170℃, and the melt index of the polypropylene was measured to be 2.5~4.0 g / 10min at 230℃ and 2.16 kg.

[0027] Further, the oxidant is any one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 626, antioxidant 1098, and antioxidant PEPQ.

[0028] The present invention also provides a method for preparing any of the above-mentioned silica-resistant anti-sticking masterbatches, comprising the following steps: weighing each raw material according to the weight parts, adding maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer and homopolymer polypropylene into an extruder, heating to 200~250℃, rotating at 150-300 r / min, and melting and plasticizing; adding modified silica and antioxidant into the extruder by side feeding, melting and blending at 200~250℃, and extruding and granulating through a twin-screw extruder to obtain silica-resistant anti-sticking masterbatch.

[0029] To better understand and implement this invention, the invention will be described in detail below. Detailed Implementation

[0030] To facilitate understanding of the present invention, it will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0031] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0032] The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] The experimental methods in the following examples or comparative examples, unless otherwise specified, are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market.

[0034] It should be noted that in this invention, the carrier resin usually refers to the resin (e.g., polypropylene) that serves as the carrier of silica / modified silica in the anti-adhesion masterbatch, and the matrix resin usually refers to the resin (e.g., polypropylene) used to form a film / a certain layer of the film.

[0035] This invention provides a silica-resistant anti-sticking masterbatch that is resistant to shedding, comprising 79.4-96.9 wt% homopolymer polypropylene, 2-10 wt% modified silica, 1-10 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, and 0.1-0.6 wt% antioxidant; the modified silica is obtained by modifying silica with a styrene-based diaminosilane coupling agent, and the amount of styrene-based diaminosilane coupling agent used is 1-5% of the mass fraction of silica.

[0036] Furthermore, the styrene-based diaminosilane coupling agent is 3-(N-styrene-methyl-2-aminoethylamino)propyltrimethoxysilane.

[0037] Furthermore, the styrene-based bisaminosilane coupling agent is obtained by a nucleophilic substitution reaction between the terminal amino group of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and the chloromethyl group of p-chloromethylstyrene to form a secondary amine.

[0038] Furthermore, the preparation method of the modified silica includes the following steps: at 100°C, an ethanol solution of styrene-based diaminosilane coupling agent is added dropwise to a silica n-butanol dispersion with a pH of 2-4; after the reaction is completed, the mixture is centrifuged, washed, and dried to obtain the styrene-based diaminosilane coupling agent.

[0039] Furthermore, the particle size D50 of the modified silica is 3~7μm.

[0040] Furthermore, the maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer is selected from one or more of Kraton FG1901G, Kraton FG1924, Taipol 7131, and Zhiyuan FG03.

[0041] Furthermore, the homopolymer polypropylene has a melting point of 160~170℃, and the melt index of the homopolymer polypropylene was measured to be 2.5~4.0 g / 10min at 230℃ and 2.16 kg.

[0042] Furthermore, the oxidant is any one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 626, antioxidant 1098, and antioxidant PEPQ.

[0043] Furthermore, the detachable silica anti-sticking masterbatch comprises 82.9~94.4wt% homopolymer polypropylene, 3~9wt% modified silica, and 2.5~7.5wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer.

[0044] The present invention also provides a method for preparing any of the above-mentioned silica-resistant anti-sticking masterbatches, comprising the following steps: weighing each raw material according to the weight parts, adding maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer and homopolymer polypropylene into an extruder, heating to 200~250℃, rotating at 150-300 r / min, and melting and plasticizing; adding modified silica and antioxidant into the extruder by side feeding, melting and blending at 200~250℃, and extruding and granulating through a twin-screw extruder to obtain silica-resistant anti-sticking masterbatch.

[0045] The physical properties and testing methods of the embodiments or comparative examples of the present invention are as follows: The composition and preparation of the film used for performance evaluation in this invention are as follows: The upper surface layer consists of 7.5 wt% resistant silica anti-sticking masterbatch and 92.5 wt% homopolymer polypropylene, the core layer is homopolymer polypropylene, and the lower surface layer is homopolymer polypropylene. The film is processed using the following biaxial stretching process: the melt extrusion temperature of the upper and lower surfaces is 200~260℃; the melt extrusion temperature of the core layer is 230~260℃; in the melt contact cooling roller step, the quench water and quench roller temperatures are 40℃; the longitudinal stretching zone temperature is 130℃; the transverse stretching zone temperature is 160℃; the longitudinal stretching ratio is 5.2 times; and the transverse stretching ratio is 8 times, resulting in a 15μm film.

[0046] Dynamic friction coefficient: According to GB / T 10006-2001 Test of friction coefficient of plastic film and sheet, the dynamic friction coefficient before and after friction is tested respectively.

[0047] Simulated friction experiment: The thin film sample was fixed and a standard friction head (covered with a cleanroom cloth) was used. A load of 200g was applied, with a reciprocating stroke of 50mm, a reciprocating speed of 50 times / minute, and a cycle factor of 100. After the test, the cleanroom cloth was removed and EDS surface scanning was performed on the cleanroom cloth under an electron microscope to analyze the silicon content on the cleanroom cloth.

[0048] The styrene-based bisaminosilane coupling agent of the present invention and the comparative examples is formed through a nucleophilic substitution reaction between N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (KH-792) and p-chloromethylstyrene. The chloromethyl group of p-chloromethylstyrene undergoes a nucleophilic substitution reaction with the amino group at the end of KH-792 to form a secondary amine, thereby forming the styrene-based bisaminosilane coupling agent. The preparation method includes the following steps: 111g of KH-792 (1.0 equivalent) and 100g of toluene (toluene is used as a reaction solvent to promote thorough mixing of the two raw materials, increase the reaction rate, and facilitate removal after the reaction) are added to a 500mL flask, the reaction temperature is controlled at 40~50℃, and the mixture is continuously stirred. 0.04 g of hydroquinone (used as a polymerization inhibitor to prevent the polymerization of the double bonds in p-chloromethylstyrene at room temperature) was dissolved in 76 g of p-chloromethylstyrene (1.0 equivalent, i.e., a molar ratio of KH-792 to p-chloromethylstyrene of 1:1). The mixed solution of triethylamine (2.0 equivalent) and p-chloromethylstyrene was added dropwise to the flask at a rate of 1 drop per second using a constant-pressure dropping funnel, with continuous stirring. After the addition was complete, the reaction temperature was adjusted to 80 °C, and the reaction was allowed to proceed for 4 hours. After reacting for 4 hours, 50 g of triethylamine was added dropwise into the flask using a constant pressure dropping funnel at a rate of 2 drops per second. Triethylamine acts as an acid-binding agent (to neutralize acidic substances generated during the reaction, thereby promoting the reaction and improving the purity of the product). A precipitate formed in the solution. The mixture was stirred at a constant temperature of 80°C for 1 hour. After the reaction was completed, the mixture was filtered, and the precipitate was washed with toluene. The washing liquid and filtrate were then transferred to a rotary evaporator for rotary evaporation to remove the solvent and obtain the target product, styrene-based diaminosilane coupling agent.

[0049] Taking 10g of silica as an example, the preparation method of modified silica in Examples 1-3 and Comparative Examples 2-7 of this invention includes the following steps: A styrene-based diaminosilane coupling agent, 2.5g of deionized water, and 25g of anhydrous ethanol are mixed to obtain a styrene-based diaminosilane coupling agent modifier ethanol solution; 10g of silica is added to 100mL of n-butanol solution, and ultrasonic treatment is performed to obtain a uniformly dispersed system, i.e., a silica n-butanol dispersion, which is poured into a 250mL flask. Under 100℃ oil bath conditions, glacial acetic acid is added to adjust the pH to 2-4, and the styrene-based diaminosilane coupling agent modifier ethanol solution is slowly added dropwise, and the reaction continues for 6 hours. After the reaction is completed, the precipitate is removed by centrifugation, and the precipitate is washed three times with anhydrous ethanol. The precipitate is dried at 70℃ for 8 hours to obtain modified silica. The preparation method of modified silica in Comparative Example 1 is the same as the above method, except that the comparative example is obtained by treating silica with KH-792, so it will not be described in detail.

[0050] The homopolymer polypropylene used in the embodiments and comparative examples of this invention is Guangxi Petrochemical L5D98C.

[0051] The maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymers used in the embodiments and comparative examples of this invention all adopted Kronen FG1901G.

[0052] The styrene-based diaminosilane coupling agent used in the embodiments and comparative examples of this invention is 3-(N-styrene-methyl-2-aminoethylamino)propyltrimethoxysilane.

[0053] The styrene-ethylene / butene-styrene block copolymer used in the comparative example of this invention is Kraton G1652.

[0054] The antioxidant used in the embodiments and comparative examples of this invention is antioxidant 1010.

[0055] It should be noted that the proportions mentioned in the embodiments or comparative examples of the present invention are all weight percentages. The components and contents of each layer in the embodiments and comparative examples of the present invention are shown in Table 1 below.

[0056] Table 1 (Unit: wt%)

[0057] Example 1 This embodiment provides a silica-resistant anti-sticking masterbatch that is resistant to shedding. Please refer to Table 1. It includes the following components: 3 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 1% of the mass fraction of silica), 2.5 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, 94.3 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0058] The preparation method includes the following steps: weigh each raw material according to the weight parts, add maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer and homopolymer polypropylene into an extruder, heat to 230℃, rotate at 200 r / min, and melt and plasticize; add modified silica and antioxidant into the extruder by side feeding, melt blend at 230℃, and extrude and granulate through a twin-screw extruder to obtain a silica anti-sticking masterbatch resistant to shedding.

[0059] Example 2 This embodiment provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 6 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 3% of the mass fraction of silica), 5 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, 88.8 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0060] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this embodiment is the same as that in Example 1, so it will not be described again.

[0061] Example 3 This embodiment provides a silica-resistant anti-sticking masterbatch that is resistant to shedding. Please refer to Table 1. It includes the following components: 9 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 5% of the mass fraction of silica), 7.5 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, 83.3 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0062] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this embodiment is the same as that in Example 1, so it will not be described again.

[0063] Comparative Example 1 This comparative example provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 6wt% KH-792 silane coupling agent modified silica (the amount of KH-792 used is 3% of the mass fraction of silica), 5wt% maleic anhydride grafted styrene-ethylene / butene-styrene block copolymer, 88.8wt% homopolymer polypropylene, and 0.2wt% antioxidant.

[0064] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this comparative example is the same as that in Example 1, so it will not be described again.

[0065] Comparative Example 2 This comparative example provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 15 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 3% of the mass fraction of silica), 5 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, 79.8 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0066] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this comparative example is the same as that in Example 1, so it will not be described again.

[0067] Comparative Example 3 This comparative example provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 6 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 0.1% of the mass fraction of silica), 5 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, 88.8 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0068] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this comparative example is the same as that in Example 1, so it will not be described again.

[0069] Comparative Example 4 This comparative example provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 6 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 10% of the mass fraction of silica), 5 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, 88.8 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0070] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this comparative example is the same as that in Example 1, so it will not be described again.

[0071] Comparative Example 5 This comparative example provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 6 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 3% of the mass fraction of silica), 93.8 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0072] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this comparative example is the same as that in Example 1, so it will not be described again.

[0073] Comparative Example 6 This comparative example provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 6 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 3% of the mass fraction of silica), 12 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, 81.8 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0074] The preparation method of the anti-sticking silica masterbatch resistant to shedding in this comparative example is the same as that in Example 1, so it will not be described again.

[0075] Comparative Example 7 This comparative example provides a silica anti-sticking masterbatch resistant to shedding, as shown in Table 1, comprising the following components: 6 wt% modified silica (the amount of styrene-based diaminosilane coupling agent used is 3% of the mass fraction of silica), 5 wt% styrene-ethylene / butene-styrene block copolymer, 88.8 wt% homopolymer polypropylene, and 0.2 wt% antioxidant.

[0076] The preparation method of the anti-adhesion silica masterbatch of this comparative example is the same as that of Example 1, so it will not be described again. The performance test and composite effect test results of the anti-adhesion silica masterbatches of Examples 1-3 and Comparative Examples 1-7 are shown in Table 2 below.

[0077] Table 2

[0078] The performance test data above shows that the film samples using the silica anti-sticking masterbatch of Examples 1-3 showed a decrease in dynamic friction coefficient of only 0.01 to 0.03 after 100 rounds of friction, and the Si content on the surface of the dust-free cloth after friction was only between 0.8% and 2.23%, with no obvious powder accumulation.

[0079] Comparative Examples 1-6 are all based on Example 2 with adjustments to the components.

[0080] The silica anti-sticking masterbatch of Comparative Example 1 was modified with the traditional silane coupling agent KH-792. The Si content on the surface of the cleanroom cloth after rubbing the prepared film sample was still significantly higher than that in Examples 1-3.

[0081] Compared with the silica anti-adhesion masterbatch of Comparative Example 2, the content of modified silica is too high. The number of micro protrusions formed by the silica anti-adhesion agent on the film surface is too high. The particles are densely packed. The tops of many protrusions are almost on the same plane. The overall micro-contour of the film tends to be flat. The actual contact area is greatly increased due to the tight adhesion of the flat surface. The prepared film sample not only has a higher initial friction coefficient than Example 2, but also a higher dynamic friction coefficient decay value after 100 rounds of friction. The Si element content on the surface of the clean cloth after friction is also significantly higher than that of Example 2.

[0082] Compared with the silica anti-sticking masterbatch of Comparative Example 3, the amount of styrene-based diaminosilane coupling agent in the modified silica was too low relative to the mass fraction of silica, and the coupling agent content was low. Only a small portion of the coupling agent reacted with silica, and the silica modification effect was not ideal. Although the initial dynamic friction coefficient was comparable to that of Example 2, the dynamic friction coefficient decay value after 100 rounds of friction was higher than that of Example 2. The Si element content on the surface of the cleanroom cloth after friction was also significantly higher than that of Example 2.

[0083] In Comparative Example 4, the amount of styrene-based diaminosilane coupling agent in the modified silica was too high relative to the mass fraction of silica. The excessive coupling agent underwent a self-polymerization reaction, forming a multi-layer coating structure. This affected the strong steric hindrance between the styrene group of the modified silica and the polypropylene molecular chain, thus reducing the bonding force between them. Therefore, the Si content on the surface of the cleanroom cloth after rubbing was also higher than that in Example 2.

[0084] The silica anti-sticking masterbatch of Comparative Example 5 did not contain maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer. The number of anhydride groups that can combine with the amino groups in the styrene-based diaminosilane coupling agent was small, which could not effectively improve the interfacial bonding force between silica particles and polypropylene. Therefore, the Si content on the surface of the cleanroom cloth after rubbing was higher than that in Example 2.

[0085] In Comparative Example 6, the content of maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer was too high, resulting in an excessive number of MAHs in the system. This led to self-polymerization and local cross-linking between MAH groups, weakening the interfacial bonding between silica particles and polypropylene. Consequently, the Si content on the surface of the cleanroom cloth after rubbing was higher than that in Example 2.

[0086] The silica anti-sticking masterbatch of Comparative Example 7 did not establish the bond between the styrene-based diaminosilane coupling agent and SEBS and PP through MAH, and could not effectively improve the interfacial bonding force between silica particles and polypropylene. Therefore, the Si element content on the surface of the cleanroom cloth after rubbing was higher than that in Example 2.

[0087] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above-described embodiments are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. Therefore, the present invention also intends to include these modifications and variations.

Claims

1. A silica-resistant, non-sticking masterbatch that resists shedding, characterized in that, It comprises 79.4~96.9 wt% homopolymer polypropylene, 2~10 wt% modified silica, 1~10 wt% maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer, and 0.1~0.6 wt% antioxidant; the modified silica is obtained by modifying silica with a styrene-based diaminosilane coupling agent, and the amount of the styrene-based diaminosilane coupling agent relative to the mass fraction of the silica is 1~5%.

2. The anti-sticking silica masterbatch resistant to shedding as described in claim 1, characterized in that, The styrene-based diaminosilane coupling agent is 3-(N-styrene-methyl-2-aminoethylamino)propyltrimethoxysilane.

3. The anti-sticking silica masterbatch resistant to shedding according to claim 2, characterized in that, The styrene-based bisaminosilane coupling agent is obtained by a nucleophilic substitution reaction between the terminal amino group of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and the chloromethyl group of p-chloromethylstyrene to form a secondary amine.

4. The anti-sticking silica masterbatch resistant to shedding as described in claim 1, characterized in that, The method for preparing the modified silica includes the following steps: at 100°C, an ethanol solution of styrene-based diaminosilane coupling agent is added dropwise to a silica n-butanol dispersion with a pH of 2-4. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain the modified silica.

5. The anti-sticking silica masterbatch resistant to shedding according to claim 1, characterized in that, The modified silica has a particle size D50 of 3~7μm.

6. The anti-sticking silica masterbatch resistant to shedding according to claim 1, characterized in that, The maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer is selected from one or more of the following: Kronen FG1901G, Kronen FG1924, Taipol 7131, and Zhiyuan FG03.

7. The anti-sticking silica masterbatch resistant to shedding according to claim 1, characterized in that, The homopolymer polypropylene has a melting point of 160~170℃, and its melt index was measured to be 2.5~4.0 g / 10min at 230℃ and 2.16 kg.

8. The anti-sticking silica masterbatch resistant to shedding according to claim 1, characterized in that, The oxidant is any one or more of antioxidant 1010, antioxidant 1076, antioxidant 168, antioxidant 626, antioxidant 1098, and antioxidant PEPQ.

9. A method for preparing a silica-resistant, non-sticking masterbatch resistant to shedding as described in any one of claims 1 to 8, characterized in that, The process includes the following steps: Weigh each raw material according to weight parts, add maleic anhydride-grafted styrene-ethylene / butene-styrene block copolymer and homopolymer polypropylene into an extruder, heat to 200~250℃, rotate at 150-300r / min, and melt and plasticize; add modified silica and antioxidant into the extruder by side feeding, melt blend at 200~250℃, and extrude and granulate through a twin-screw extruder to obtain a silica-resistant anti-sticking masterbatch resistant to shedding.

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