Fluorocarbon modified polymer composite slide and extrusion molding process thereof

Abstract

This invention discloses a fluorocarbon-modified polymer composite material slide and its extrusion molding process, belonging to the technical field of polymer composite material products. The slide has a homogeneous structure, formed by melt blending and extrusion of a polyolefin matrix resin, nano-inorganic fillers modified with a fluorocarbon coupling agent, and cage-like polysilsesquioxane. The cage-like polysilsesquioxane dissolves and remains latent in the melt at the processing temperature, crystallizing in situ during the cooling and setting stage, constructing a three-dimensional nanophysical network within the matrix as a locking framework to inhibit the migration of low molecular weight components to the surface. The nano-fillers modified with the fluorocarbon coupling agent are thermodynamically enriched and locked onto the surface, forming a long-lasting low-friction layer. This scheme, through a latent-self-assembled staggered structure construction strategy, balances multiple performance requirements in a homogeneous material, including processing fluidity, resistance to low molecular weight component precipitation, and long-lasting low friction. The process is compatible with existing extrusion lines and is easy to implement.

Description

Technical Field

[0001] This invention relates to the field of polymer composite material products and their molding and processing technology. Specifically, it relates to a polyolefin slide suitable for long-term outdoor use, and more particularly to a slide and its extrusion molding process that combines long-term low friction on the surface and resistance to low molecular weight analysis in a uniform material structure. Background Technology

[0002] Large plastic components such as outdoor playground slides and water park slides are typically made of high-density polyethylene or polypropylene through extrusion molding. Over long-term use, these products gradually develop surface roughness, dust accumulation, and a decline in aesthetics, affecting the user experience. The industry is familiar with this phenomenon, but at the engineering level, it has long been attributed to natural material aging or surface wear, lacking targeted solutions that address the issue from the perspective of the material's internal mass transfer mechanisms.

[0003] After in-depth analysis of the outdoor failure process of polyolefin slide rails, the inventors discovered that the core mechanism of the aforementioned surface degradation phenomenon is not simply thermo-oxidative aging or physical scratches, but a previously undisclosed "stress pumping" effect. Specifically, the stearate lubricants, low molecular weight waxes, and low molecular weight oligomers inherent in the resin itself introduced into the polyolefin matrix during processing are not in a static equilibrium state within the product. When the slide rail is subjected to repeated exposure to sunlight and alternating mechanical loads such as foot traffic and sliding outdoors, these low molecular weight components in the amorphous regions are gradually "pumped" to the surface of the product by continuous cyclic stress, forming a submicron-level enrichment layer. This enrichment layer alters the tribological properties of the surface and adsorbs environmental dust. Moreover, even after the surface layer is naturally worn away or washed away by water, the internal low molecular weight components continue to migrate outwards, causing the problem to exhibit persistent and self-healing deterioration characteristics.

[0004] Theoretically, the direct way to suppress the aforementioned "stress pumping" behavior is to construct a physical barrier network within the polyolefin matrix that can effectively resist cyclic stress and constrain the migration of low molecular weight components. However, this approach immediately faces a physical contradiction in engineering: if a conventional non-migrating rigid barrier structure is used, it will be present in the system throughout the melt processing stage, significantly increasing melt viscosity, hindering the uniform mixing of components, and leading to severe deterioration of extrusion processability; conversely, if a rigid framework is not introduced to maintain processing fluidity, the product lacks an effective stress dispersion and locking structure, making it impossible to solve the precipitation problem. In other words, the processing stage requires the system to maintain a low viscosity as much as possible to obtain good fluidity, while the service stage requires a dense rigid network within the system to resist stress and lock in low molecular weight components. These two requirements have proven difficult to achieve simultaneously in the same material system under the traditional technical framework.

[0005] Furthermore, slide rail products have high requirements for surface friction coefficient. Existing technologies have introduced solutions to improve surface smoothness by adding fluoropolymer micropowders or perfluoropolyethers to the polyolefin matrix. While these solutions can reduce the initial friction coefficient, the fluorinated components have extremely poor compatibility with the polyolefin matrix, easily leading to macroscopic phase separation during processing and forming visible agglomerates. This not only affects the appearance but also becomes a stress concentration source, causing a significant decrease in impact strength. Simultaneously, some low-molecular-weight fluorinated additives themselves face the problem of continuous migration to the surface and wear and tear, resulting in insufficient long-term effectiveness.

[0006] Therefore, there is an urgent need in this field for a technical solution that can automatically construct a physical network within the matrix after molding, capable of resisting cyclic stress and blocking the migration path of low molecular weight components, without sacrificing processing fluidity, and simultaneously construct a stable, long-lasting, low-friction surface layer on the surface. This invention is proposed precisely to address this practical need. Summary of the Invention

[0007] In view of this, the present invention proposes a fluorocarbon modified polymer composite material slide and its extrusion molding process that realizes a new material design paradigm of "latent during processing and locked after molding" in a uniform structure.

[0008] The technical solution of this invention is achieved as follows: This invention provides a fluorocarbon-modified polymer composite material slide, which has a uniform structure and is made by melt blending and extrusion of raw materials including a polyolefin matrix resin, nano-inorganic fillers modified with a fluorocarbon coupling agent, and cage-type polysilsesquioxane. The cage-type polysilsesquioxane is selectively used as a latent nano-skeleton precursor. Utilizing its reversible dissolution within the polyolefin processing temperature range and its in-situ crystallization during cooling, the thermally induced phase change property allows it to remain in a dissolved state in the melt during extrusion without substantially hindering flow. After the slide cools and solidifies, it spontaneously constructs a three-dimensional nanophysical network within the matrix in the form of crystallization, forming a locking skeleton that inhibits the migration of low molecular weight components to the surface. The nano-inorganic fillers modified with a fluorocarbon coupling agent are directionally enriched on the surface of the product during melt extrusion and cooling, and are locked in the surface area, forming a long-lasting low-friction layer with wear-resistant properties. The structural characteristics of this slide product are inseparable from the phase evolution of the raw materials during the process. The uniform structure of the product contains a three-dimensional nanophysical network formed by in-situ crystallization and fluorocarbon-modified nanofillers distributed to the surface concentration gradient.

[0009] In this invention, "latent nanostructure precursor" is a general definition of the function of cage-like polysilsesquioxane in the design. This definition should not be understood as a simple functional limitation, but rather based on the experimentally verified physicochemical properties of cage-like polysilsesquioxane, namely its temperature-dependent reversible dissolution-crystallization behavior in polyolefin melts. In short, at processing temperatures, POSS molecular clusters are thermally dissociated, dissolving or uniformly dispersing in the polyolefin melt at the molecular or nanoscale. When the temperature drops below a certain threshold, the solubility of POSS in the matrix decreases sharply, and the molecules crystallize in situ under van der Waals forces, assembling into nanocrystalline domains. These crystalline domains further interconnect or become entangled with polymer segments, forming a three-dimensional continuous physical network within the product. This phase transition process occurs entirely after extrusion molding, not during the screw processing stage. Because the three-dimensional network that acts as the "locking skeleton" grows after molding, rather than being a pre-formed rigid filler already present in the feeding section, the present invention can maintain a relatively low melt viscosity during the processing stage and achieve a significant anti-precipitation effect during service. This constitutes the essential feature that distinguishes the present invention from all pre-formed filler barrier solutions.

[0010] In some embodiments, the polyolefin matrix resin is homopolymer polypropylene or high-density polyethylene. The rationale for choosing these two resins is that they are both mainstream base materials for slide rail products, possessing good mechanical properties and outdoor weather resistance, and both exhibit a clear amorphous-crystalline two-phase structure. The migration of low molecular weight components mainly occurs along the amorphous regions, meaning that the greater the proportion of amorphous regions in the matrix, the wider the migration channels for low molecular weight components. The crystallinity of homopolymer polypropylene and high-density polyethylene is typically between 60% and 80%, with amorphous regions existing in a confined state between spherulites. This provides structural feasibility for POSS to preferentially crystallize and precipitate in the amorphous regions during the cooling stage and "block" these channels.

[0011] In some embodiments, the cage-like polysilsesquioxane is octaisobutyl cage-like polysilsesquioxane or octaphenyl cage-like polysilsesquioxane. These two types of POSS are chosen because their organic peripheral groups have similar solubility parameters to the polyolefin segments, enabling good melt dissolution or nanoscale dispersion at processing temperatures, rather than forming micron-sized droplets. Their inorganic silica cage core provides strong van der Waals interaction sites upon cooling, driving stable crystallization behavior. Regarding the dosage, if the dosage is too low (e.g., below 0.5 wt%), the density of the crystal domains formed after POSS crystallization is insufficient, and the spacing between the crystal domains is too large, failing to form an effective through-network. This limits the constraint on the movement of amorphous segments, allowing low molecular weight components to still migrate "bypass" isolated POSS crystal domains and continue moving towards the surface. If the dosage is too high (e.g., exceeding 3.0 wt%), the POSS may not completely dissolve in the melt, and the remaining undissolved clusters contribute significantly to the melt viscosity during processing, thus weakening the processability advantage of the solution.

[0012] In some embodiments, the amount of the cage-like polysilsesquioxane is 1.0 to 2.0% by weight of the polyolefin matrix resin. This range is a window obtained after further weighing the aforementioned upper and lower limits: at this addition amount, POSS can be sufficiently dissolved in the polyolefin melt at the processing temperature, while the density of the crystal domains formed after cooling precipitation is sufficient to transform the network from an "island" state to a continuous or semi-continuous state, thereby achieving effective locking.

[0013] In some embodiments, the nano-inorganic filler modified with a fluorocarbon coupling agent is obtained by surface grafting of nano-silica with an average particle size of 20 to 100 nm using a 1H,1H,2H,2H-perfluorooctyltriethoxysilane coupling agent. The surface of nano-silica is rich in silanol groups under normal conditions, exhibiting hydrophilicity and a tendency to severely aggregate in non-polar polyolefin matrices. The introduction of the fluorocarbon coupling agent accomplishes two key interfacial tasks: first, the triethoxysilane end of the coupling agent undergoes hydrolysis and condensation in the presence of trace amounts of moisture, forming Si-O-Si covalent bonds with the silanol groups on the nano-silica surface, anchoring the fluorocarbon chains to the filler surface; second, its perfluorocarbon tail chains extend outward, endowing the modified nanoparticles with extremely low surface energy. This chemically anchored structure fundamentally solves the defects of traditional physical blending, such as incompatibility between fluorinated components and the matrix, easy macroscopic phase separation, and easy wear and consumption during long-term use. Because the fluorocarbon segments are not free in the system as independent molecules, but are "tethered" to the nanofiller by covalent bonds, and the nanofiller is fixed inside the matrix, the low-friction layer will not be easily wiped away or quickly consumed by water flow, thus exhibiting long-lasting performance.

[0014] In some embodiments, the amount of 1H,1H,2H,2H-perfluorooctyltriethoxysilane accounts for 5 to 15% of the mass of the nano-inorganic filler. When the amount of coupling agent is less than 5%, the silanol groups on the surface of the nano-filler are not completely covered, and the unmodified hydrophilic regions may still lead to local aggregation; while when it exceeds 15%, the excess coupling agent molecules may undergo self-condensation side reactions, forming a loose multilayer rather than a dense monolayer with oriented arrangement on the filler surface, which is actually detrimental to the full orientation and end exposure of the fluorocarbon segments.

[0015] In some embodiments, the amount of the nano-inorganic filler modified with the fluorocarbon coupling agent accounts for 1 to 5% by weight of the polyolefin matrix resin. This amount determines the areal density of the effective fluorinated component in the low-friction layer of the slide surface. When it is less than 1%, the coverage of the fluorocarbon segments after surface enrichment is limited, and the initial and long-term low-friction effect of the slide is not ideal. When it is more than 5%, on the one hand, it increases the raw material cost, and on the other hand, too many nanofillers are forcibly dispersed in the matrix, which will increase the rigidity of the material and decrease the impact toughness due to the reinforcing effect of the nanoparticles themselves. Moreover, the volume occupied by these fillers will compete with the space required for POSS crystallization and precipitation, interfering with the complete construction of the locking skeleton.

[0016] In some embodiments, the raw material further includes a polyolefin elastomer, comprising 5 to 15% by weight of the polyolefin matrix resin. The nanocrystalline domains formed after POSS crystallization are rigid physical cross-linking points. While constraining the movement of chain segments in the amorphous region and locking in low molecular weight components, they inevitably increase the matrix's resistance to impact loads. With local chain segments rigidly constrained, the energy dissipation path of the material under rapid loads is reduced, and the notched impact strength may decrease. The introduction of the polyolefin elastomer is precisely to compensate for this effect: the elastomer exists in the matrix as a micron-sized dispersed phase, acting as a stress concentration point and energy dissipation unit. During impact events, it absorbs energy through its own cavitation and plastic deformation, thereby maintaining the overall impact strength at a level comparable to that of pure matrix resin. This toughening strategy does not conflict with the locking function of the POSS skeleton, because the elastomer phase and the POSS crystalline domains can coexist spatially in the amorphous region. The elastomer dissipates impact energy, while the POSS skeleton resists cyclic creep and stress transmission at low strain rates; their functions are clearly defined.

[0017] In some embodiments, the raw materials further include high molecular weight antioxidants, which are a mixture of hindered phenolic antioxidants and phosphite antioxidants, with a total amount accounting for 0.2 to 0.4% by weight of the polyolefin matrix resin, wherein the molecular weight of the hindered phenolic antioxidant is not less than 1000; and high molecular weight processing lubricants with a number average molecular weight of 3000 to 5000, with an amount accounting for 0.5 to 1.5% by weight of the polyolefin matrix resin. The use of high molecular weight additives in the raw materials is intended to reduce the total load of low molecular weight components in the formulation from the source. Hindered phenolic antioxidants with a molecular weight below 1000 pose a risk of surface migration and dissolution with water flow during long-term use; polyethylene grafted maleic anhydride wax lubricants with a number average molecular weight above 3000 have a much lower migration rate than conventional paraffin or fatty acid salt lubricants, and will not become a new source of precipitation while meeting the lubrication requirements of extrusion processing. Meanwhile, in the amorphous regions covered and constrained by the POSS framework network, the effective diffusion coefficient of these high molecular weight additives is further reduced, making it difficult for them to migrate to the surface even after long-term high-temperature aging.

[0018] In other embodiments, the raw materials may also include light stabilizers, colorants or other functional additives, which are preferably high molecular weight or have reactive anchoring groups to ensure their long-term stability and low migration in the entire formulation system.

[0019] This invention also provides an extrusion molding process for preparing the aforementioned slide. The key to this process lies in coordinating the processing temperature window with the dissolution-crystallization phase transition window of POSS. Specifically, it includes: premixing a polyolefin matrix resin, the nano-inorganic filler modified with a fluorocarbon coupling agent, the cage-like polysilsesquioxane, and additives to obtain a premix; feeding the premix into a twin-screw extruder for melt blending at 180 to 220°C. Within this temperature range, the cage-like polysilsesquioxane is fully dissolved in the polyolefin melt, uniformly latent in the form of single molecules or nanoclusters, while the fluorocarbon coupling agent-modified nanofiller is sheared and dispersed by the screw; immediately introducing the melt preform extruded from the die into a cooling medium at 70 to 90°C for slow cooling and shaping. During the slow cooling and shaping stage, as the matrix temperature slowly decreases, the dissolved POSS molecules reach supersaturation in the amorphous region and begin to crystallize and precipitate in situ, assembling into rigid nanocrystalline domains with a size of 1 to 3 nm. These crystalline domains further form a three-dimensional nanophysical network penetrating the matrix. Meanwhile, the nanofillers modified with fluorocarbon coupling agents spontaneously and directionally accumulate on the surface of the product under thermodynamic drive, and form a stable low-friction surface layer with the fluorocarbon segments on their surface oriented outward.

[0020] The core of this process lies in the selection of the cooling temperature range. If brittle POSS is rapidly cooled with room temperature water, it may not have enough time to complete the transformation from a dissolved to a crystalline state within the matrix. It may remain in the matrix as amorphous aggregates or "frozen" in a partially dissolved state, failing to form a regular, sufficiently cohesive network of nanocrystalline domains, significantly reducing the locking effect. Conversely, if the cooling temperature is set too high, the matrix crystallization and shaping process is too slow, making the product prone to deformation during traction and shaping, affecting dimensional accuracy. A cooling water temperature of 70 to 90°C is a suitable window that balances sufficient POSS crystallization and precipitation with production efficiency.

[0021] In some embodiments, the slow cooling and shaping time is 5 to 30 seconds. This time range is sufficient to allow the article to slowly cross the crystallization exothermic temperature zone of POSS from an extrusion temperature of approximately 200°C, while simultaneously completing the crystallization and shaping of the matrix itself. The specific cooling time can be adjusted according to the cross-sectional thickness of the article.

[0022] In some embodiments, the twin-screw extruder operates at a screw speed of 200 to 400 rpm, and a vacuum devolatilization of -0.08 to -0.09 MPa is applied in the middle and later stages of the extruder. The purpose of the middle and later stage vacuum devolatilization is to remove trace amounts of ethanol gas that may be generated during the hydrolysis and condensation of the fluorocarbon coupling agent, as well as trace amounts of residual moisture in the raw materials, to prevent these volatiles from forming microbubble defects inside the product, thus ensuring the density and surface quality of the final product.

[0023] In some embodiments, the pre-preparation step of the nano-inorganic filler modified with the fluorocarbon coupling agent is as follows: the nano-inorganic filler is dried at 100 to 110°C to remove physically adsorbed water from its surface, and then 8 to 12% (by mass) of 1H,1H,2H,2H-perfluorooctyltriethoxysilane is added. The mixture is stirred in a high-speed mixer at 2000 to 3000 rpm for 20 to 40 minutes, followed by drying to remove residual solvent, resulting in the pre-modified nano-filler. This pre-modification step allows the fluorocarbon coupling agent to achieve initial directional anchoring on the surface of the nano-filler, effectively preventing the coupling agent from failing to uniformly cover the filler surface due to free migration during subsequent twin-screw blending, thereby improving modification efficiency and product quality consistency.

[0024] The present invention has the following advantages over the prior art: This invention introduces a cage-like polysilsesquioxane, a latent framework precursor with thermally reversible dissolution-crystallization behavior, in synergy with nanofillers anchored by fluorocarbon coupling agents. This achieves a staggered structure construction strategy—latent dissolution during processing and in-situ network formation after cooling and molding—for the first time in a homogeneous polyolefin channel. Compared to solutions that rely on a rigid filler network throughout the processing stage, this invention maintains good extrusion processability while creating a three-dimensional nano-locking framework within the product that effectively resists cyclic stress and blocks the migration of low-molecular-weight components. Compared to solutions that rely on the physical application or migration of low-molecular-weight fluorinated additives for surface lubrication, this invention covalently anchors fluorocarbon segments to the surface region, achieving a long-lasting low-friction effect with wear resistance and erosion resistance. Compared to relying on high-molecular-weight additives to replace traditional small-molecule additives for a passive "source reduction" approach to precipitation, this invention actively inhibits precipitation from the perspective of physically blocking stress transmission and molecular migration pathways, resulting in a more significant and lasting effect. The solution achieves the organic unity of multiple performance objectives such as anti-precipitation, long-term low friction and impact toughness in a single homogeneous material through the synergistic combination of stress dispersion and spatial locking effect of the POSS skeleton, stable lubrication effect of surface anchored fluorocarbon layer, and impact energy dissipation function of optional elastomeric phase. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 Step 1: Preparation of nano-silica modified with a fluorocarbon coupling agent. Nano-silica with an average particle size of 50 nm was dried at 105 °C for 2 hours to remove physically adsorbed water from the surface. 100 parts by weight of the dried nano-silica were placed in a high-speed mixer, and 12 parts by weight of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (pre-diluted with an equal mass of anhydrous ethanol) were added. The mixture was stirred at 2500 rpm for 30 minutes. After stirring, the material was dried at 120 °C for 1 hour to remove ethanol and residual water, yielding nano-silica pre-modified with a fluorocarbon coupling agent. This was then sealed for later use.

[0027] Step 2, Premixing. Take 100 parts by weight of homopolymer polypropylene resin (MFR=3.0g / 10min), 3 parts by weight of nano-silica prepared in Step 1 with fluorocarbon coupling agent surface modification, 1.5 parts by weight of octaisobutyl cage-type polysilsesquioxane, 10 parts by weight of polyolefin elastomer (POE, ENGAGE 8157), 0.3 parts by weight of high molecular weight antioxidant compound (Irganox 1010 and Irgafos168 compounded in a 1:1 ratio), and 1.0 part by weight of polyethylene grafted maleic anhydride wax with a number average molecular weight of approximately 4000. Premix the mixture in a high-speed mixer at 500 rpm for 5 minutes to obtain the premix.

[0028] Step 3: Melt Blending Extrusion. The premix obtained in Step 2 is added to the main feed port of a twin-screw extruder. The temperatures of each section of the extruder are set sequentially to 180℃, 190℃, 200℃, 210℃, and 210℃ (die), with the screw speed set to 300 rpm. A vacuum of -0.085 MPa is applied in the later section of the extruder. Under these temperature conditions, octaisobutyl cage-type polysilsesquioxane is fully dissolved in the polypropylene melt, and the nano-silica modified with the fluorocarbon coupling agent is uniformly dispersed by the screw shearing.

[0029] Step 4: Slow Cooling and Shaping. The molten preform extruded from the die is directly introduced into a circulating cooling water bath at 80°C for 15 seconds. During this cooling process, the dissolved octaisobutyl cage-like polysilsesquioxane reaches supersaturation in the polypropylene matrix, crystallizing in situ and forming nanocrystalline domains with a size of 1–3 nm, constructing a three-dimensional nanophysical network. Simultaneously, nano-silica modified with a fluorocarbon coupling agent is thermodynamically driven to directionally accumulate on the preform surface and is locked in the surface area after cooling. After traction and length-limited cutting, a polypropylene slide profile sample with a uniform structure is obtained.

[0030] Example 2 Step 1: Prepare nano-silica with a surface modified by a fluorocarbon coupling agent. The preparation method and parameters are the same as in Step 1 of Example 1.

[0031] Step 2, Premixing. Take 100 parts by weight of high-density polyethylene resin (HDPE, MFR=0.5g / 10min), 2 parts by weight of nano-silica prepared in Step 1 with fluorocarbon coupling agent surface modification, 1.0 part by weight of octaisobutyl cage-type polysilsesquioxane, 5 parts by weight of polyolefin elastomer (POE), 0.25 parts by weight of high molecular weight antioxidant compound (Irganox 1010 and Irgafos 168 compounded in a 1:1 ratio), and 0.8 parts by weight of polyethylene grafted maleic anhydride wax with a number average molecular weight of approximately 4000. Premix the mixture in a high-speed mixer at 500 rpm for 5 minutes to obtain the premix.

[0032] Step 3: Melt Blending Extrusion. Add the premix obtained in Step 2 to the main feed port of a twin-screw extruder. Set the temperatures of each section of the extruder sequentially to 180℃, 195℃, 205℃, 215℃, and 215℃ (die), and set the screw speed to 350 rpm. Apply a vacuum of -0.085 MPa in the middle and rear sections of the extruder.

[0033] Step 4: Slow cooling and shaping. The molten preform extruded from the die is directly introduced into a circulating cooling water bath at 85°C for 20 seconds. Subsequent traction and cutting steps are the same as in Example 1, resulting in a polyethylene slide rail profile sample with a uniform structure.

[0034] Example 3 Step 1: Prepare nano-silica with a surface modified by a fluorocarbon coupling agent. The preparation method and parameters are the same as in Step 1 of Example 1.

[0035] Step 2, Premixing. Take 100 parts by weight of homopolymer polypropylene resin (MFR=3.0g / 10min), 4 parts by weight of nano-silica prepared in Step 1 with fluorocarbon coupling agent surface modification, 2.0 parts by weight of octaphenyl cage-type polysilsesquioxane, 12 parts by weight of polyolefin elastomer (POE), 0.35 parts by weight of high molecular weight antioxidant compound (Irganox 1010 and Irgafos 168 compounded in a 1:1 ratio), and 1.2 parts by weight of polyethylene grafted maleic anhydride wax with a number average molecular weight of approximately 4000. Premix the mixture in a high-speed mixer at 500 rpm for 5 minutes to obtain the premix.

[0036] Step 3: Melt blending extrusion. The temperatures of each section of the extruder are set sequentially to 185℃, 195℃, 210℃, 220℃, and 220℃ (die), the screw speed is set to 280 rpm, and the vacuum degree is -0.085 MPa. The remaining operations are the same as step 3 in Example 1.

[0037] Step 4: Slow cooling and shaping. The cooling water temperature was set to 75°C, and the cooling time was 18 seconds. Subsequent traction and cutting steps were the same as in Example 1, resulting in a polypropylene slide rail profile sample with a uniform structure.

[0038] Comparative Example 1 Step 1: Premixing. Take 100 parts by weight of homopolymer polypropylene resin (MFR=3.0g / 10min), 3 parts by weight of ordinary nano-silica (average particle size 50nm) without any surface treatment, 10 parts by weight of polyolefin elastomer (POE, ENGAGE 8157), 0.3 parts by weight of high molecular weight antioxidant compound (Irganox 1010 and Irgafos 168 compounded in a 1:1 ratio), and 1.0 part by weight of conventional low molecular weight paraffin lubricant. Premix these ingredients in a high-speed mixer at 500rpm for 5 minutes to obtain the premix. This formulation does not contain any cage-like polysilsesquioxanes, and the nano-silica is not modified with fluorocarbon coupling agents.

[0039] Step 2: Melt blending extrusion. The extruder temperature setting and screw speed are the same as in step 3 of Example 1, but vacuum devolatilization is not applied.

[0040] Step 3: Cooling and Shaping. The molten preform extruded from the die is rapidly cooled and shaped in room temperature tap water (approximately 25°C) without slow cooling. Subsequent traction and cutting steps are the same as in Example 1, yielding polypropylene slide profile samples.

[0041] Comparative Example 2 Step 1: Premixing. Take 100 parts by weight of homopolymer polypropylene resin (MFR=3.0g / 10min), 1.5 parts by weight of octaisobutyl cage-type polysilsesquioxane, 10 parts by weight of polyolefin elastomer (POE, ENGAGE 8157), 0.3 parts by weight of high molecular weight antioxidant compound (Irganox 1010 and Irgafos 168 compounded in a 1:1 ratio), and 1.0 part by weight of polyethylene grafted maleic anhydride wax with a number average molecular weight of approximately 4000. Premix these ingredients in a high-speed mixer at 500 rpm for 5 minutes. This formulation does not contain any nanofillers modified with fluorocarbon coupling agents.

[0042] Step 2: Melt blending extrusion. The extruder temperature setting and screw speed are the same as in step 3 of Example 1, and vacuum devolatilization is applied.

[0043] Step 3: Cooling and Shaping. The material is rapidly cooled and shaped using room temperature tap water (approximately 25°C). Subsequent traction and cutting steps are the same as in Example 1, yielding polypropylene slide rail profile samples.

[0044] Comparative Example 3 Step 1: Prepare nano-silica with a surface modified by a fluorocarbon coupling agent. The preparation method and parameters are the same as in Step 1 of Example 1.

[0045] Step 2, Premixing. Take 100 parts by weight of homopolymer polypropylene resin (MFR=3.0g / 10min), 3 parts by weight of nano-silica prepared in Step 1 with fluorocarbon coupling agent surface modification, 10 parts by weight of polyolefin elastomer (POE, ENGAGE 8157), 0.3 parts by weight of high molecular weight antioxidant compound (Irganox 1010 and Irgafos 168 compounded in a 1:1 ratio), and 1.0 part by weight of polyethylene grafted maleic anhydride wax with a number average molecular weight of approximately 4000. Premix these ingredients in a high-speed mixer at 500 rpm for 5 minutes. This formulation does not contain any cage-like polysilsesquioxanes.

[0046] Step 3: Melt blending extrusion. The extruder temperature setting and screw speed are the same as in Step 3 of Example 1, and vacuum devolatilization is applied.

[0047] Step 4: Slow cooling and shaping. The cooling water temperature and cooling time are the same as in Step 4 of Example 1. Subsequent traction and cutting steps are the same as in Example 1, and polypropylene slide rail profile samples are obtained.

[0048] Comparative Example 4 Step 1: Prepare nano-silica with a surface modified by a fluorocarbon coupling agent. The preparation method and parameters are the same as in Step 1 of Example 1.

[0049] Step 2, Premix. Take 100 parts by weight of homopolymer polypropylene resin (MFR=3.0g / 10min), 3 parts by weight of nano-silica prepared in Step 1 with fluorocarbon coupling agent surface modification, 1.5 parts by weight of octaisobutyl cage-type polysilsesquioxane, 10 parts by weight of polyolefin elastomer (POE, ENGAGE 8157), 0.3 parts by weight of high molecular weight antioxidant compound (Irganox 1010 and Irgafos168 compounded in a 1:1 ratio), and 1.0 part by weight of conventional low molecular weight paraffin lubricant (to replace the high molecular weight lubricant), and premix them in a high-speed mixer at 500rpm for 5 minutes.

[0050] Step 3: Melt blending extrusion. The extruder temperature setting and screw speed are the same as in Step 3 of Example 1, and vacuum devolatilization is applied.

[0051] Step 4: Slow cooling and shaping. The cooling water temperature and cooling time are the same as in Step 4 of Example 1. Subsequent traction and cutting steps are the same as in Example 1, and polypropylene slide rail profile samples are obtained.

[0052] Performance verification The following tests were conducted on the performance of the slide profile samples obtained in each embodiment and comparative example. The test items and methods are as follows: (1) Evaluation of processing fluidity: The stable operating torque of the main motor of the twin-screw extruder during the extrusion process was recorded. The torque value of Comparative Example 1 was used as a baseline (represented as 100%), and the torque values ​​of other examples were expressed as a percentage relative to Comparative Example 1. The higher the torque value, the greater the melt viscosity and the worse the processing fluidity.

[0053] (2) Low molecular weight group precipitate test: Each sample was cut into 100mm×100mm pieces and placed in a 60℃ constant temperature forced-air drying oven for continuous aging for 168 hours. After removal, the surface of the sample was wiped with lint-free wiping paper under constant pressure, and the weight gain of the wiping paper was measured and converted into the amount of precipitate per unit area (mg / m²). 2 ).

[0054] (3) Surface water contact angle test: After aging for 168 hours, the static contact angle of deionized water on the surface of the test piece was measured at 25°C using a contact angle measuring instrument. Five points were measured for each test piece and the average value was taken.

[0055] (4) Surface dynamic friction coefficient test: Take the test piece after aging for 168 hours, use a friction coefficient tester, with a stainless steel slider as the grinding pair, and measure the dynamic friction coefficient at a sliding speed of 100 mm / min.

[0056] (5) Notched impact strength test: In accordance with GB / T 1843 standard, a notched impact test specimen of cantilever beam was prepared and tested at 23℃.

[0057] Performance test results The formulation characteristics and performance test data of each embodiment and comparative example are summarized in the table below.

[0058]

[0059] Results Analysis The data in the table clearly shows that: A comparison of Example 1 and Comparative Example 1 shows that, under the premise of essentially no loss of processing fluidity (torque 97% vs 100%), the amount of precipitate in the present invention is reduced from 38.4 mg / m³. 2 Significantly reduced to 8.2 mg / m³ 2 The reduction was 78.6%, the surface friction coefficient decreased from 0.28 to 0.12, the contact angle increased from 78° to 118°, and the impact strength increased from 5.8 kJ / m. 2 Increased to 10.8 kJ / m 2 This set of comparative data fully verifies the comprehensive advantages of the present invention in terms of processability, anti-precipitation, low friction, and impact resistance.

[0060] The comparison between Example 1 and Comparative Example 2 highlights the contribution of fluorocarbon-modified nanofillers. Comparative Example 2, which does not contain fluorocarbon nanofillers, has a surface friction coefficient of 0.24 and a contact angle of only 86°, far inferior to 0.12 and 118° of Example 1. This demonstrates that although the POSS framework can lock in the analysis of low molecular weight components, it cannot endow the surface with low friction properties on its own. The surface enrichment of fluorocarbon-modified nanofillers is the key to achieving long-term low friction.

[0061] The comparison between Example 1 and Comparative Example 3 highlights the role of the POSS framework. Comparative Example 3 contains fluorocarbon nanofillers but no POSS, and its precipitate content is 28.5 mg / m³. 2 Although compared to Comparative Example 1, which contains no fluorocarbon nanofiller, the concentration is 38.4 mg / m³. 2 The concentration was reduced (attributed to the physical barrier effect of the nanofiller itself), but still significantly higher than the 8.2 mg / m³ in Example 1. 2 This indicates that the barrier effect of individual nanofillers is limited, and the three-dimensional nanophysical network formed by the in-situ crystallization of POSS during the cooling stage is the core mechanism for achieving deep anti-precipitation.

[0062] The comparison between Example 1 and Comparative Example 4 shows that even with the presence of both the POSS framework and the fluorocarbon-modified filler, the amount of precipitates is still higher than in Example 1 if a low-molecular-weight conventional paraffin is used as the lubricant (Comparative Example 4), and the impact strength is reduced. This is because the low-molecular-weight lubricant itself constitutes a new source of precipitates, increasing the locking burden on the POSS framework.

[0063] Example 2 demonstrates the applicability of the scheme in high-density polyethylene matrix, with performance indicators showing a consistent trend with Example 1. Example 3, using octaphenyl POSS with appropriate dosage adjustment, exhibits superior precipitation inhibition, indicating that different POSS varieties can realize the technical concept of this invention.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fluorocarbon modified polymer composite slide rail, having a homogeneous structure, is manufactured by melt blending and extrusion of raw materials containing the following components: Polyolefin matrix resin; Nano-silica surface-modified with a fluorocarbon coupling agent, wherein the fluorocarbon coupling agent is 1H,1H,2H,2H-perfluorooctyltriethoxysilane, and its amount accounts for 5-15% of the mass of nano-silica; the amount of nano-silica surface-modified with the fluorocarbon coupling agent accounts for 1-5% by weight of the polyolefin matrix resin. Cage-type polysilsesquioxanes have the property of dissolving in polyolefin melts at temperatures above 180°C and crystallizing out when cooled to below 90°C. The amount of these polysilsesquioxanes is 0.5 to 3.0% by weight of the polyolefin matrix resin.

2. The slide rail according to claim 1, characterized in that, The polyolefin matrix resin is homopolymer polypropylene or high-density polyethylene.

3. The slide rail according to claim 1, characterized in that, The average particle size of the nano-silica is 20-100 nm, and the amount of 1H,1H,2H,2H-perfluorooctyltriethoxysilane is 8-12% of the mass of the nano-silica.

4. The slide rail according to claim 1, characterized in that, The cage-like polysilsesquioxane is octaisobutyl cage-like polysilsesquioxane or octaphenyl cage-like polysilsesquioxane, and its amount accounts for 1.0 to 2.0% of the polyolefin matrix resin by weight.

5. The slide rail according to claim 1, characterized in that, The raw materials also include polyolefin elastomers, which account for 5 to 15% of the weight of the polyolefin matrix resin.

6. The slide rail according to claim 1, characterized in that, The raw materials also include: The compound of hindered phenolic antioxidants and phosphite antioxidants, the total amount of which accounts for 0.2 to 0.4% by weight of the polyolefin matrix resin, wherein the molecular weight of the hindered phenolic antioxidant is not less than 1000; Polyethylene grafted with maleic anhydride wax with a number average molecular weight of 3000-5000 is used in an amount of 0.5-1.5% by weight of the polyolefin matrix resin.

7. An extrusion molding process for preparing the slide rail according to any one of claims 1 to 6, characterized in that, include: A premix is ​​prepared by premixing a polyolefin matrix resin, the nano-silica modified with a fluorocarbon coupling agent, the cage-type polysilsesquioxane, and additives. The premixed material is fed into a twin-screw extruder and melt-blended at 180–220°C to dissolve the cage-like polysilsesquioxane in the polyolefin melt. The melt is extruded from the die, and the resulting preform is placed in cooling water at 70-90°C for slow cooling and shaping, so that cage-like polysilsesquioxane crystallizes and precipitates in the polyolefin matrix, forming a three-dimensional nanophysical network.

8. The process according to claim 7, characterized in that, The cooling time for the slow cooling and shaping process is 5 to 30 seconds.

9. The process according to claim 7, characterized in that, The twin-screw extruder has a screw speed of 200 to 400 rpm, and a vacuum of -0.08 to -0.09 MPa is applied in the middle and rear sections of the extruder.

10. The process according to claim 7, characterized in that, The preparation steps of the nano-silica modified with the fluorocarbon coupling agent include: drying the nano-silica at 100-110°C, then adding 1H,1H,2H,2H-perfluorooctyltriethoxysilane, stirring in a high-speed mixer at 2000-3000 rpm for 20-40 minutes, and then drying.

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