In-depth Exploration Focusing on Nylon PBT Brush Filament Itself

1. What Is the Essential Definition of Nylon PBT Brush Filament?

Nylon PBT Brush Filament is a high-performance composite brush filament engineered by homogeneously blending two distinct polymers: nylon (a polyamide) and polybutylene terephthalate (PBT), a type of thermoplastic polyester. This intentional fusion leverages the complementary strengths of each material to create a filament with balanced mechanical and chemical properties tailored for diverse brushing applications.

Nylon, predominantly represented by Nylon 6 and Nylon 66 in brush filament production, contributes key attributes derived from its molecular structure. Nylon 6, with a linear chain of six carbon atoms, offers exceptional elasticity and fatigue resistance—critical for brushes that undergo repeated bending, such as household dusters. Nylon 66, featuring a more rigid structure with six carbons on both sides of the amide bond, enhances tensile strength and wear resistance, making it ideal for filaments subjected to heavy friction, like those in industrial deburring brushes. Both variants introduce a degree of softness, allowing the filament to conform to irregular surfaces without causing scratches.

PBT, in contrast, brings robust chemical stability and thermal resilience to the blend. Its aromatic ring structure and ester linkages grant it superior resistance to oils, solvents, and weak acids/alkalis—properties absent in pure nylon. PBT also boasts a higher melting point (approximately 225°C) compared to Nylon 6 (220°C) and Nylon 66 (260°C), though its real advantage lies in maintaining structural integrity in sustained high-temperature environments (up to 120°C) where nylon alone would soften. This makes PBT the backbone of filaments used in industrial ovens or automotive engine bays.

The blending ratio of nylon to PBT is dynamically adjustable to target specific performance profiles, typically ranging from 30:70 to 70:30. A 30% nylon/70% PBT formulation prioritizes chemical and heat resistance, suited for laboratory cleaning brushes or industrial solvent-based scrubbers. Conversely, a 70% nylon/30% PBT mix emphasizes elasticity and softness, ideal for cosmetic brushes or precision instrument dusters. Intermediate ratios (e.g., 50:50) strike a balance, making them versatile for general-purpose tools like kitchen scrub brushes.

Production of Nylon PBT Brush Filament involves sophisticated melt compounding: the polymers are dried to less than 0.02% moisture (to prevent hydrolysis), then fed into a twin-screw extruder where they are melted, mixed at 230-260°C, and extruded through spinnerets with micro-sized orifices (0.05-2 mm diameter). Post-extrusion, the filaments undergo controlled stretching (2-4x their original length) to orient molecular chains, enhancing tensile strength by 30-50%. A final heat-setting step stabilizes the structure, ensuring dimensional consistency even after repeated use.

The result is a filament that transcends the limitations of its individual components: it retains nylon’s ability to flex without permanent deformation while adopting PBT’s resistance to harsh chemicals and temperature fluctuations. This synergy enables its use across a spectrum of environments—from the mild conditions of residential bathrooms to the aggressive settings of chemical processing plants—solidifying its role as a versatile workhorse in brush technology.

2. What Are the Specific Types of Nylon PBT Brush Filament? What Are the Differences in Characteristics Between Different Types?

Nylon PBT Brush Filament can be divided into various types according to the ratio of nylon to PBT, diameter size, surface treatment methods, etc.

In terms of the ratio of nylon to PBT, there are mainly nylon-dominated types and PBT-dominated types. Nylon-dominated Nylon PBT Brush Filament, with a nylon content of 60%-70%, has more prominent elasticity and toughness, and a relatively soft feel, suitable for scenarios with high surface requirements that need gentle cleaning, such as cleaning precision instruments like optical lenses and high-end furniture made of polished wood. The PBT-dominated type, containing 60%-70% PBT, has stronger chemical resistance and heat resistance, and relatively high hardness, suitable for brushes that need to come into contact with chemical reagents such as acids and alkalis or be used in high-temperature environments around 120-150°C, such as industrial cleaning brushes for machinery parts and kitchen cleaning brushes for pots and pans.

In terms of diameter size, it can be divided into small-diameter and large-diameter types. Small-diameter Nylon PBT Brush Filament usually has a diameter between 0.1-0.5 mm, characterized by high softness and good flexibility, which can penetrate into some small gaps for cleaning. For example, brushes for cleaning gaps in electronic devices like smartphone charging ports and computer keyboards often use this type of brush filament. Large-diameter brush filaments generally have a diameter of 0.5-2 mm, with high hardness and strong wear resistance, suitable for cleaning work that requires large friction, such as floor cleaning brushes for concrete floors and pipeline cleaning brushes for metal pipes with heavy dirt.

In addition, according to different surface treatment methods, there are two types: smooth surface and rough surface. Brush filaments with a smooth surface, treated with a special coating, have low friction and are not easy to damage the surface being cleaned or painted, suitable for painting paints and coatings on car bodies and furniture. Brush filaments with a rough surface, achieved through sandblasting or other processes, have high friction and good cleaning effect, often used for brushes that remove stubborn stains like rust on metal surfaces and old paint layers.

To more intuitively show the differences in characteristics of different types of Nylon PBT Brush Filament, we can present them through the following table:

3. What Scenarios Are Nylon PBT Brush Filament Suitable for? What Are the Different Application Points in Each Scenario?

Nylon PBT Brush Filament has a wide range of application scenarios, covering industrial, household, medical, automotive and other fields, and even some emerging areas. Its adaptability stems from the adjustable blend ratio and diverse processing technologies, which allow it to meet the unique demands of each scenario.

In the industrial field, it is a staple material for manufacturing industrial cleaning brushes, polishing brushes, deburring brushes, and even specialized tools like conveyor belt cleaning brushes. In heavy-duty industrial cleaning—such as in factories processing machinery parts, chemical plants, and refineries—the key application point is that the brush filaments must exhibit exceptional chemical resistance and wear resistance. These brushes often come into contact with heavy oils, lubricants, and aggressive cleaning agents (like alkaline degreasers or acidic rust removers), so PBT-dominated Nylon PBT Brush Filament with a large diameter (1.5-2 mm) is preferred. For example, in the automotive component manufacturing industry, brushes used to clean engine blocks after machining are made with such filaments. They can withstand the abrasive friction from cast iron or aluminum surfaces while resisting the corrosion from industrial detergents containing phosphates. In contrast, polishing brushes for metal surfaces (such as stainless steel panels or copper fittings) rely on a higher nylon content (60%-70%) in the blend. The elasticity of nylon ensures that the brush filaments conform to the surface contours, achieving a uniform, scratch-free polish—critical for products where aesthetics matter, like decorative metal parts. Deburring brushes, used to remove sharp edges from machined parts, require a balance of stiffness and flexibility; a 50:50 nylon-PBT blend with a medium diameter (0.8-1.2 mm) works best, as it can dislodge burrs without damaging the part’s dimensions.

In daily life, Nylon PBT Brush Filament enhances the functionality of numerous household tools, from kitchen brushes to floor scrubbers. Kitchen brushes are divided into specialized types: those for non-stick cookware, ceramic dishes, and cast-iron pans. For non-stick pans, where scratching the Teflon coating is a major concern, small-diameter (0.2-0.4 mm) filaments with a high nylon content (70%) and a smooth surface treatment are essential. These filaments gently lift oil and food residues without abrading the coating. Ceramic dish brushes, on the other hand, need slightly more stiffness to tackle baked-on food; a blend with 50% PBT and a diameter of 0.5-0.7 mm is ideal, as it balances cleaning power with gentleness on fragile ceramics. Bathroom brushes are designed to combat soap scum, hard water stains, and mold on tiles, grout, and shower doors. Here, large-diameter (0.8-1.5 mm) PBT-dominated filaments (60%-70% PBT) excel—their rigidity allows them to scrub grout lines effectively, while their moisture resistance prevents mold growth in the humid bathroom environment. Floor brushes for home use, whether for hardwood, tile, or laminate floors, use a mix of filament lengths and diameters. The outer filaments are longer and softer (nylon-dominated) to sweep dust, while shorter, stiffer inner filaments (PBT-dominated) tackle ground-in dirt, ensuring thorough cleaning without scratching delicate flooring.

The medical field demands the highest standards of hygiene and precision, making Nylon PBT Brush Filament a valuable material for medical device cleaning tools. These brushes are used to clean intricate components like surgical forceps, endoscopes, and dental handpieces—items with small lumens, hinges, and crevices where contaminants can hide. The key requirements here are non-toxicity, chemical resistance (to withstand sterilization agents like ethylene oxide or hydrogen peroxide), and a smooth surface to prevent bacterial adhesion. PBT-dominated filaments (70% PBT) with a small diameter (0.1-0.3 mm) are the norm. For example, endoscope cleaning brushes use ultra-thin filaments that can navigate the narrow channels of the instrument, removing biological debris without damaging the delicate inner lining. After use, these brushes must withstand autoclaving (high-pressure steam at 134°C), a process that PBT’s heat resistance handles effectively. Additionally, the filaments are often treated with an antimicrobial coating to further reduce the risk of cross-contamination in healthcare settings.

In the automotive industry, Nylon PBT Brush Filament is used in a variety of brushes tailored to specific cleaning and maintenance tasks. Car exterior brushes, including those for washing the body, wheels, and windows, require filaments that clean thoroughly without marring the paint or glass. For the car body, a blend with 60% nylon and 40% PBT, with a diameter of 0.5-0.8 mm, is used—nylon’s softness prevents scratches, while PBT adds durability. Wheel brushes, which tackle brake dust and road grime on alloy rims, need stiffer filaments (1.0-1.5 mm diameter, 60% PBT) to reach between spokes and remove stubborn debris. Under-the-hood cleaning brushes, used to clean engine bays, must resist oil, grease, and high temperatures (from the engine after operation). Here, PBT-dominated filaments (70% PBT) with heat resistance up to 150°C are essential, as they can withstand contact with warm engine parts and resist degradation from oil-based cleaners. Even car interior brushes, like those for upholstery or dashboard vents, use Nylon PBT filaments—softer, nylon-rich blends (0.3-0.5 mm) for fabric seats to avoid pilling, and medium-stiffness filaments for vents to dislodge dust without damaging plastic components.

Emerging application scenarios continue to expand the use of Nylon PBT Brush Filament, particularly in renewable energy and electronics manufacturing. In solar panel maintenance, keeping the panels clean is vital for maximizing energy output—even a thin layer of dust can reduce efficiency by 10%-20%. Brushes for this purpose use filaments with a 50:50 nylon-PBT blend, a diameter of 0.6-0.9 mm, and UV-resistant additives. This combination ensures they can sweep away dust, pollen, and bird droppings without scratching the panel’s anti-reflective coating, while the UV resistance prevents filament degradation from prolonged sun exposure. In electronics manufacturing, where precision is paramount, brushes are used to clean circuit boards, remove flux residues, and dust sensitive components like microchips. These brushes use ultra-fine filaments (0.05-0.2 mm diameter) with a high nylon content (80%), which are soft enough to avoid damaging delicate electronics but rigid enough to dislodge tiny particles. The filaments are also static-dissipative, preventing electrostatic discharge that could harm electronic components.

Another growing area is agricultural equipment cleaning. Brushes used to clean farm machinery (like tractors, harvesters, and milking equipment) must withstand exposure to fertilizers, pesticides, and organic residues. PBT-dominated Nylon PBT filaments (60% PBT) with a large diameter (1.2-2 mm) are ideal here—they resist chemical corrosion from agricultural chemicals and are tough enough to remove mud and crop residues from metal surfaces. For food-grade agricultural equipment (such as grain silos or fruit washing machines), the filaments are made with food-safe additives to ensure they don’t leach harmful substances, meeting strict regulatory standards like FDA or EU 10/2011.

4. What Are the Advantages and Disadvantages of Nylon PBT Brush Filament in Performance Compared with Other Material Brush Filaments?

Compared with other common brush filament materials, Nylon PBT Brush Filament has its own advantages and disadvantages in performance.

Compared with pure nylon brush filaments, Nylon PBT Brush Filament has better chemical resistance and heat resistance. Pure nylon brush filaments, especially Nylon 6, are prone to deformation, aging and even cracking when exposed to some strong chemical reagents like concentrated acids or in high-temperature environments above 100°C. However, due to the PBT component, Nylon PBT Brush Filament can better resist chemical corrosion and high-temperature effects, maintaining its shape and performance in such conditions. However, in terms of elasticity and toughness, Nylon PBT Brush Filament is slightly inferior to pure nylon brush filaments. In some scenarios with extremely high elasticity requirements, such as in brushes used for delicate brushing operations that require frequent bending and recovery, pure nylon brush filaments may be more advantageous.

Compared with polypropylene (PP) brush filaments, Nylon PBT Brush Filament has higher wear resistance and hardness. PP brush filaments are relatively soft, have poor wear resistance—they tend to fray quickly when used on rough surfaces—and a short service life, usually lasting only a few months with regular use. In contrast, Nylon PBT Brush Filament can withstand greater friction and has a longer service life, often lasting 1-2 years under similar usage conditions. However, the cost of PP brush filaments is relatively low, about 30%-50% lower than that of Nylon PBT Brush Filament, and they are more competitive in some scenarios with low performance requirements and pursuit of low cost, such as disposable cleaning brushes.

Compared with steel wire brush filaments, the biggest advantage of Nylon PBT Brush Filament is that it will not scratch the surface being cleaned or processed. Steel wire brush filaments have extremely high hardness and good cleaning effect, but they are easy to leave scratches on delicate surfaces like glass, polished metal and plastic, and are suitable for some hard surfaces that are not afraid of scratches, such as rust removal on thick steel plates. While Nylon PBT Brush Filament is softer and suitable for various precision instruments, high-end furniture and other surfaces that are afraid of scratches. However, in terms of the ability to remove stubborn stains like thick rust layers and heavy scale, Nylon PBT Brush Filament is not as good as steel wire brush filaments, which can tackle such tough dirt more efficiently.

Compared with natural bristle brush filaments, such as those from pigs or goats, Nylon PBT Brush Filament has better water resistance and durability. Natural bristles absorb water easily, which can lead to mold growth and deterioration over time, especially in humid environments. They also tend to break and wear out faster with frequent use. Nylon PBT Brush Filament, on the other hand, is water-resistant, dries quickly, and is less prone to mold, making it more durable. However, natural bristles have better paint-holding capacity, making them preferred for high-quality painting work, whereas Nylon PBT Brush Filament may not hold paint as well but is easier to clean.

For a clearer comparison, the following is a table of advantages and disadvantages of Nylon PBT Brush Filament compared with other material brush filaments:

5. What Key Indicators of the Product Itself Should Be Focused on When Selecting Nylon PBT Brush Filament?

When selecting Nylon PBT Brush Filament, it is necessary to pay attention to multiple key indicators to ensure that it can meet specific usage requirements.

First is the diameter and length. The size of the diameter directly affects the hardness and flexibility of the brush filament. As mentioned earlier, brush filaments of different diameters are suitable for different scenarios, so the appropriate diameter should be selected according to the actual application scenario. For example, for cleaning electronic components with small gaps, a diameter of 0.1-0.2 mm is suitable, while for cleaning large floor areas, 1-2 mm is more appropriate. The length needs to be determined according to the size and usage requirements of the brush. For a small hand-held brush, a length of 3-5 cm may be sufficient, while for a large industrial brush, 10-15 cm could be needed. Too long or too short will affect the usage effect of the brush—too long may cause the brush to be cumbersome to handle, and too short may not reach the required cleaning area.

Second is elasticity and toughness. It can be judged through simple tests. Bend the brush filament by hand to a 90-degree angle and then release it, observing its recovery speed and degree. Brush filaments with good elasticity can recover to their original shape within 1-2 seconds and are not easy to break. For toughness testing, pull the brush filament with a moderate force; good toughness means it can be stretched by 10%-15% of its original length without breaking. Brush filaments with good toughness are not easy to be broken when stretched by external force and can withstand a certain amount of tension.

Third is chemical resistance and heat resistance. If the brush filament will be used in contact with chemical reagents or in high-temperature environments, it is necessary to focus on testing its chemical resistance and heat resistance. You can take a small amount of brush filament samples, soak them in the corresponding chemical reagents (such as 5% sulfuric acid solution or 5% sodium hydroxide solution) for 24 hours, and observe whether they are deformed, discolored, or become brittle. For heat resistance testing, place the samples in an oven at 120°C for 4 hours and check for softening, melting, or shape changes.

In addition, surface smoothness is also important. For scenarios where it is necessary to avoid scratching the surface being cleaned, brush filaments with a smooth surface should be selected. This can be judged by observation and touch. Brush filaments with a smooth surface feel delicate without burrs or roughness, and under light, there are no obvious uneven reflections.

Finally, attention should also be paid to the wear resistance of the brush filament. You can simulate the usage environment by rubbing the brush filament against a rough surface (like sandpaper) 100 times and observing the degree of wear. Brush filaments with good wear resistance can still maintain a good shape and performance after this test, with little to no fraying or shortening.

6. What Are the Precautions Related to the Product Itself When Making Brushes with Nylon PBT Brush Filament?

When making brushes with Nylon PBT Brush Filament, meticulous attention to details related to the product itself is crucial to ensure the final brush performs as intended and has a long service life. These precautions span from the initial cutting of filaments to the final quality inspection, each step directly impacting the brush’s functionality and durability.

The cutting phase is the first critical step. Achieving uniform length across all filaments is non-negotiable, as uneven lengths can lead to inconsistent pressure distribution during use—resulting in some areas being over-cleaned or under-cleaned, and an unprofessional appearance. Laser cutting machines are ideal for this task, as they can maintain length deviations within 0.1 mm, far exceeding the precision of traditional blade cutters. It’s also essential to match the cutting speed to the filament’s diameter: thicker filaments (1.5-2 mm) require slower cutting speeds to prevent fraying, while thinner ones (0.2-0.5 mm) can be cut more quickly but still demand sharp, well-maintained equipment. Dull blades or lasers with misaligned focal points can crush filament ends, creating micro-fractures that weaken the filaments and cause them to break prematurely during use. After cutting, a quick visual inspection under magnification can reveal any damaged ends, which should be discarded to avoid compromising the brush’s performance.

In the tufting process, both density and depth must be calibrated to the brush’s intended use. Tuft density—measured in tufts per square centimeter (tufts/cm²)—varies significantly: a delicate cosmetic brush might require 30-40 tufts/cm² to ensure soft, even application, while a heavy-duty industrial brush needs 15-20 tufts/cm² to allow filaments room to flex and dislodge tough debris. Overly dense tufting traps dirt between filaments, making cleaning difficult and promoting bacterial growth, especially in humid environments like bathrooms. Conversely, sparse tufting reduces the brush’s contact area with the surface, diminishing its effectiveness. Tufting depth is equally critical: inserting filaments 2-3 mm into the brush base (whether plastic, wood, or metal) strikes a balance between security and flexibility. Shallow insertion (less than 1.5 mm) risks filaments pulling out under moderate pressure, while deep insertion (more than 4 mm) compresses the filaments at the base, stiffening the brush and reducing its ability to conform to irregular surfaces. For brushes used in high-vibration environments—such as industrial machinery cleaners—slightly deeper tufting (3-3.5 mm) may be necessary to prevent loosening over time.

Securing filaments to the brush handle requires careful consideration of both method and materials. Glue bonding is preferred for most applications, but the adhesive must be compatible with both Nylon PBT and the handle material. Epoxy-based glues work well for plastic handles, forming a strong bond that resists water and mild chemicals, making them suitable for kitchen or bathroom brushes. For wooden handles, polyurethane adhesives are better, as they flex slightly with the wood’s natural expansion and contraction, preventing cracks. Mechanical fixing—such as stapling or crimping—is common in industrial brushes, where high torque or repeated use might stress glued joints. However, staples must be positioned to avoid piercing the filaments themselves, as punctures weaken the filaments and create entry points for moisture. Regardless of the method, filaments must be aligned straight during fixing; even a 5-degree skew can cause uneven wear, with one side of the brush deteriorating faster than the other. Using jigs or alignment guides during assembly ensures consistent positioning.

Post-production quality inspection is the final safeguard. Beyond checking for loose tufts (a gentle pull of 5-10 Newtons should not dislodge any filaments), inspectors must verify filament integrity. Brushes intended for sensitive surfaces—like automotive paint or medical devices—should undergo a “scratch test”: dragging the brush across a polished glass plate under standard pressure and examining for micro-abrasions, which indicate burrs or irregularities in the filaments. For brushes used with chemicals, a small sample should be submerged in the target solution (e.g., industrial degreasers or medical disinfectants) for 24 hours, then checked for swelling, discoloration, or brittleness—signs that the filament or adhesive is incompatible with the chemical. Finally, functional testing simulates real-world use: a kitchen brush might be used to scrub a greasy pan 100 times, while an industrial brush could be run against a metal surface under typical pressure. This ensures the brush maintains its shape and performance before reaching the end user.

7. How Do Different Environmental Conditions Affect the Performance of Nylon PBT Brush Filament Itself?

Different environmental conditions exert distinct and measurable impacts on the performance of Nylon PBT Brush Filament, influencing its mechanical properties, durability, and functionality over time. Understanding these effects is critical for optimizing the filament’s lifespan and ensuring consistent performance in specific applications.

Temperature fluctuations represent one of the most impactful environmental stressors. Nylon PBT Brush Filament typically operates within a stable range of -20°C to 120°C, but extremes outside this window trigger significant changes. At temperatures exceeding 120°C—common in industrial drying processes, near engine exhausts, or around high-heat appliances—the PBT component’s crystalline structure begins to destabilize. By 150°C, the filament may soften noticeably, losing up to 30% of its original hardness, and at 180°C, melting can occur, causing filaments to fuse together or deform irreversibly. This is particularly problematic in automotive underhood cleaning brushes, where accidental contact with hot manifolds (reaching 200°C+) can render the brush useless within minutes. Conversely, sub-zero temperatures below -20°C—such as in polar regions or freezer facilities—slow molecular motion, reducing the filament’s flexibility. At -30°C, the filament’s impact resistance drops by 40%, making it prone to shattering under even minor bending. For instance, brushes used to clean frozen food processing equipment must be stored at room temperature between uses; otherwise, repeated exposure to -25°C conditions can cause filaments to snap during routine scrubbing.

Humidity levels also play a pivotal role, albeit more gradually. Nylon PBT exhibits low moisture absorption (typically 0.8-1.2% by weight in saturated conditions), but prolonged exposure to high humidity—above 80% relative humidity—induces subtle yet cumulative changes. In steamy bathrooms or tropical climates, the filaments absorb trace moisture, which plasticizes the material slightly: hardness decreases by 5-8%, and the brush feels noticeably softer. While this may improve gentleness on delicate surfaces, it also reduces scrubbing efficiency for tough grime. More critically, high humidity creates a microenvironment conducive to microbial growth. Mold spores, particularly Aspergillus and Penicillium, thrive on the filament’s surface, feeding on residual organic matter (like soap scum or food particles). Over 3-6 months, this biofilm can degrade the filament’s surface, causing micro-cracks and weakening the structure—evident in bathroom brushes that develop frayed, discolored tips. In arid environments (below 30% relative humidity), the opposite effect occurs: the filament loses ambient moisture, becoming 10-15% more brittle. This is problematic in desert-region industrial settings, where brushes used for outdoor equipment cleaning often develop splintered filaments after 2-3 months of use, requiring more frequent replacement.

Chemical exposure poses a direct and often rapid threat to filament integrity. Strong acids (pH < 2) and alkalis (pH > 12) attack the polymer chains: sulfuric acid, for example, hydrolyzes the ester bonds in PBT, causing filaments to swell, discolor (turning brown or black), and eventually dissolve within hours. Even milder chemicals—such as household bleach (sodium hypochlorite) or industrial degreasers (containing surfactants and solvents)—accelerate aging with repeated contact. A 5% bleach solution, common in commercial kitchens, can reduce filament elasticity by 20% after 50 cycles of exposure and rinsing, leading to premature sagging. Automotive cleaning products with citrus-based solvents (d-limonene) have a similar effect, causing the nylon component to degrade, resulting in a “fuzzy” texture on filament surfaces that traps dirt rather than removing it. Notably, PBT-dominated blends (60%+ PBT) fare better than nylon-rich ones in chemical environments, retaining 15-20% more of their original strength after exposure to mild acids or alkalis.

Ultraviolet (UV) radiation, particularly the UV-B spectrum (280-315 nm) in sunlight, initiates photo-oxidation of the polymer chains. Outdoor brushes—used for solar panel cleaning, building facade maintenance, or garden tool scrubbing—are most vulnerable. Over 6-12 months of direct sunlight exposure, UV rays break chemical bonds in both nylon and PBT, reducing molecular weight by 15-25%. This manifests as: decreased tensile strength (filaments snap under 30% less force), color fading (from white/clear to yellowish), and surface chalking (a powdery residue). In field tests, solar panel cleaning brushes left outdoors year-round show a 40% reduction in service life compared to identical brushes stored indoors between uses. UV stabilizers, added during filament production, can mitigate this effect—extending outdoor lifespan by 2-3 times—but they are less effective in high-altitude regions (like mountainous areas) where UV intensity is amplified.

8. What Are the Special Features of the Raw Materials for Making Nylon PBT Brush Filament? How Do They Affect Product Performance?

The raw materials for making Nylon PBT Brush Filament, nylon and PBT, have unique structural and performance characteristics, and their combination directly determines the comprehensive performance of the final product.

Nylon, as a polyamide material, has a molecular chain containing repeating amide groups (-CONH-). This structure gives nylon good hydrogen bonding ability, which makes the molecular chains have strong interaction forces. This is the fundamental reason why nylon has excellent elasticity and toughness. When the nylon filament is stretched by an external force, the molecular chains can be oriented along the direction of the force, and after the external force is removed, the hydrogen bonds can help the molecular chains return to their original state, thus showing good elastic recovery. In addition, the molecular chain of nylon has a certain degree of flexibility, which makes the nylon filament have good bending resistance and is not easy to break during use. For example, Nylon 66, with a more regular molecular structure, has higher crystallinity than Nylon 6, so its strength and wear resistance are better, which is why some high-performance Nylon PBT Brush Filaments will choose Nylon 66 as the nylon component.

PBT is a polyester material with a molecular chain composed of terephthalate groups and butylene groups. The terephthalate group is a rigid aromatic ring structure, which gives PBT high rigidity and heat resistance. The butylene group, as a flexible chain segment, balances the rigidity of the molecular chain to a certain extent, making PBT have good processability. The ester bond (-COO-) in the molecular chain of PBT has good chemical stability, so PBT has strong resistance to most chemicals, especially organic solvents and weak acids and alkalis. This is why PBT-dominated Nylon PBT Brush Filaments are more suitable for scenarios involving chemical contact. In addition, PBT has a relatively high melting point (about 225°C), which is higher than that of nylon (Nylon 6 has a melting point of about 220°C, and Nylon 66 is about 260°C), so adding PBT can improve the overall heat resistance of the brush filament.

The ratio of nylon to PBT in the raw materials has a crucial impact on the performance of the product. When the nylon content is high (such as 60%-70%), the brush filament inherits more of the elasticity and toughness of nylon, and the feel is softer, which is suitable for occasions that require gentle contact with the cleaned surface. For example, in the production of makeup brushes, a higher proportion of nylon is often added to make the brush filaments soft and comfortable when touching the skin. When the PBT content is high (such as 60%-70%), the brush filament has better heat resistance and chemical resistance, and the hardness is higher, which is suitable for industrial cleaning and other harsh environments. For example, in the production of brushes used in automobile painting workshops, where they may come into contact with paint thinners and high-temperature drying environments, a higher proportion of PBT is needed to ensure the stability of the brush filaments.

The quality of raw materials is also an important factor affecting product performance. High-purity nylon and PBT raw materials can ensure the stability of the brush filament performance. If the raw materials contain impurities, such as small molecule compounds or other polymers, it may lead to uneven distribution of the molecular structure of the brush filament, resulting in inconsistent performance of the brush filaments in the same batch. For example, if there are excessive impurities in PBT, it may reduce the chemical resistance of the brush filament, making some filaments more susceptible to corrosion than others when in contact with chemicals.