Flame-Retardant & Custom Glass Fiber Prepregs | Weihai Dushi

Core classification: Accurate division based on performance orientation and application scenarios

The Glass fiber preprep category system is rich and diverse, and can be divided into four mainstream categories based on resin type, fiber arrangement, functional characteristics, and glass fiber type. Each type of product focuses on differentiated application scenarios, with strict repetition control below 50%, achieving precise adaptation to the needs of different industries.

1. Functional boundary division by resin type: thermosetting and thermoplastic

The resin system is the core element that determines the molding characteristics and application scope of Glass fiber prepreg, which can be divided into two basic categories. The two have distinct differences in curing mechanism and performance focus:

• Thermosetting Glass Fiber Prepreg: Based on epoxy resin, phenolic resin, polyester resin, etc., it requires irreversible cross-linking and curing through heating and pressure. It is currently the mainstream category in the market, accounting for over 82% by 2024. Among them, epoxy resin based products are widely used in aerospace structural components, high-end electronic equipment casings, and other scenarios due to their balanced mechanical properties (tensile strength can reach over 320MPa) and excellent adhesion; Phenolic resin based products have excellent flame retardancy as their core advantage, with low smoke density and low toxicity during combustion, making them the preferred choice for interior decoration of rail transit carriages and fire-resistant components of ships; Polyester/vinyl ester based products have lower costs and are suitable for cost sensitive general scenarios such as marine decks and industrial storage tanks. The core characteristics of this type of Glass fiber prereg are stable structure and high dimensional accuracy after curing, but the molding cycle is relatively long (usually 30-90 minutes) and difficult to recycle.
• Thermoplastic Glass Fiber Prepreg: Made of meltable resins such as polyetheretherketone (PEEK), polypropylene (PP), and polyamide (PA), it has reversible properties of "heating softening cooling curing" and has grown rapidly in recent years, with a market share of 18% by 2024. Its outstanding advantage is high molding efficiency, which shortens the cycle time by more than 60% compared to thermosetting products. The single batch molding time can be controlled within 10-20 minutes, and it can be recycled and reused, meeting the large-scale production needs of new energy vehicle body parts, home appliance shells, and other products. For example, car door panels made of PP based Glass fiber prereg have a weight reduction of 40% compared to traditional metal components, and can repair some damage by heating after collision, thereby improving their service life.

2. Fiber Layout: Unidirectional and Braided Mechanical Performance Differentiation Design

The arrangement of glass fibers directly determines the directionality of the mechanical properties of Glass fiber preforms, forming two core categories for different stress scenarios:

• Unidirectional Glass Fiber Prepreg: Glass fibers are arranged in parallel along a single direction, with a directional consistency of over 99.5%, resulting in the ultimate mechanical properties of the material in the fiber axis. The tensile modulus can reach over 28GPa, while the lateral performance is relatively weak. This type of product is mainly used for structural components that can withstand unidirectional loads, such as aircraft wing reinforcement ribs, wind turbine blade main beams, bridge reinforcement layers, etc. Through multi-directional stacking design, complex stress requirements can be achieved. Its surface density covers 80g/㎡ to 450g/㎡, and can be accurately selected according to the load size. For example, the main beam of a 10MW wind turbine blade uses 300g/㎡ unidirectional glass fiber prereg, which can reduce weight by 25% while increasing rigidity by 30%.
• Weaving Glass Fiber Prepreg: Glass fibers are interwoven and formed in plain weave, diagonal weave, satin weave, and other ways, with multi-directional balanced distribution of mechanical properties and better drapability and impact resistance. Flat weave products have a dense structure, strong wear resistance, and are suitable for pipeline anti-corrosion coatings and electronic equipment protective shells; Twill weave products have excellent flexibility and can fit complex curved surfaces, used for ship hulls and car body coverings; Satin woven products are characterized by high impact strength, with a tensile strength of up to 280MPa, suitable for aerospace interior parts and high-end sports equipment. Products with different weaving methods can be paired with 1K to 24K different fiber bundle specifications, forming a diverse range of choices from delicate textures to rough structures.

3. Customized derivative categories for special scenarios based on functional characteristics

For extreme environments or special needs, Glass fiber preprep has developed multiple functional sub categories, becoming the key to expanding application boundaries:

• High temperature resistant Glass fiber prepreg: using modified epoxy resin or polyimide resin, the long-term use temperature can reach 150-350 ℃, and the mechanical property retention rate at high temperatures exceeds 85%. For example, Hexcel's BMS 8-139 series products use HexPy ®  F161 resin system, with a curing temperature of 350 ° F, suitable for high-temperature scenarios such as aircraft engine peripheral components and industrial kiln structural components.
• Flame retardant Glass fiber prereg: Added with phosphorus nitrogen halogen-free flame retardant, the flame retardant performance can reach UL94 V0 level. Some products have passed aviation certifications such as BMS 8-80, such as Solvay's TY6 CL1 GR A product, which uses Cycom ®  4102 polyester resin is specifically used for scenarios with extremely high fire safety requirements, such as aircraft interiors and rail transit carriages.
• Weather resistance Glass fiber prepreg: the resin is added with anti ultraviolet and anti-aging ingredients, which can have a service life of more than 15 years in outdoor exposure and humid environment, and the smoke density rating (SDR) is less than 20. It is suitable for outdoor billboards, bridge protection boards, offshore wind power equipment and other scenarios.
• High frequency insulation Glass fiber prereg: optimizes the dielectric properties of the resin, with a dielectric constant of ≤ 3.2 and a dielectric loss tangent of ≤ 0.005, becoming the core material for 5G base station antenna covers and radar covers. For example, Air Preg PE CF 6550 uses S-2 glass fiber, specifically suitable for aviation radar cover applications.

4. Differentiation of Basic Performance by Glass Fiber Type

The material properties of glass fiber itself provide different performance substrates for Glass fiber prepregrades, which are mainly divided into three categories:

• E-glass fiber based prepreg: the most commonly used basic category, with excellent electrical insulation and chemical stability, moderate cost, suitable for most common scenarios such as electronic equipment and industrial storage tanks, accounting for more than 75% of the total sales of Glass fiber prepreg.
• S-2 Glass Fiber Based Prepreg: High strength type, with tensile strength increased by more than 30% compared to E-glass fiber, and better impact resistance. It is mainly used in aerospace structural components, high-end wind turbine blades and other scenarios with strict strength requirements.
• C-glass fiber based preprereg: With excellent corrosion resistance as its core, it can resist the erosion of strong acid and alkali media, and is suitable for strong corrosive environments such as chemical pipelines and offshore platform structural components.

Core advantage: Six core characteristics that reshape the application value of materials

The reason why Glass fiber prepreg stands out among many composite materials and becomes a "must-have material" for high-end manufacturing is due to its comprehensive advantages in mechanical properties, process adaptation, environmental adaptation, and other dimensions. These characteristics together build its irreplaceable market position.

1. Balanced mechanical properties and lightweight advantages

Glass fiber prepreg perfectly combines the performance advantages of glass fiber and resin, achieving a balance of "high strength+lightweight". The tensile strength of ordinary E-glass fiber based prepreg can reach 280-350MPa, which is 1.2-1.5 times that of ordinary steel, while the density is only 1.8-2.0g/cm ³, less than 1/4 of steel and 2/3 of aluminum alloy. In the field of rail transit, the interior panels and seat frames made of Glass fiber preprereg can reduce the weight of a single carriage by more than 250kg, saving about 42000 kWh of electricity per train per year; In the aerospace field, the aircraft radar cover adopts S-2 glass fiber based preprereg, which reduces the weight by 55% compared to traditional metal covers and improves the signal penetration rate by 15%. In addition, its bending modulus can reach 25-30GPa, which is not easily deformed after long-term use and is suitable for various load-bearing structural scenarios.

2. Excellent environmental adaptability and durability

Glass fiber prepreg has environmental resistance far beyond traditional materials, making it a reliable choice for complex working conditions. In terms of corrosion resistance, after soaking C-glass fiber based preprepreg in a 5% sulfuric acid solution for 1000 hours, the mechanical performance degradation rate is less than 5%, far better than the 40% degradation rate of galvanized steel plate, suitable for strong corrosive environments such as marine and chemical industries; In terms of weather resistance, products with added UV resistant ingredients have a color retention rate of over 90% after 5 years of outdoor exposure, without cracking or powdering; In terms of fatigue resistance, under dynamic load cycles (such as car bumps and fan rotation), the fatigue strength retention rate reaches over 88%, which is 10 percentage points higher than the industry average. After using Glass fiber prereg for wind turbine blades, the service life can be extended to over 20 years.

3. Highly flexible customization capability

Glass fiber preprep can achieve full dimensional parameter customization, accurately matching personalized needs of different industries. The resin system can be adjusted according to the scene, such as high-temperature resistant phenolic resin for aviation and fast curing epoxy resin for automobiles; The precision of resin content control reaches ± 0.5%, ensuring the consistency of product performance; The width supports customization of 0.5m-2.0m, and large ship hulls can use 2.0m wide products, reducing the number of joint seams by more than 50%; The functional characteristics can be combined and stacked, such as composite functions such as "flame retardant+anti-static" and "high temperature resistance+corrosion resistance". For example, the composite function Glass fiber prereg used in rail transit carriage components not only meets the UL94 V0 flame retardant requirements, but also has anti-static performance with a surface resistance of ≤ 10 ΩΩ.

4. Excellent process adaptation and molding efficiency

Glass fiber preform is compatible with mainstream composite material forming processes such as hot press cans, compression molding, vacuum bags, and winding, and is suitable for various needs from single piece customization to mass production. The compression molding process is suitable for standardized components (such as car seat frames), and the single-mode production time can be controlled within 15-30 minutes with a dimensional accuracy error of ≤± 0.2mm. The hot press can molding is suitable for high-end aerospace components, and the internal defect rate of the product is less than 0.3% through pressure control of 0.8-1.2MPa and temperature control of 120-180 ℃; Spiral forming is suitable for cylindrical components such as pipelines and pressure vessels. The directional arrangement of glass fibers allows the axial and circumferential strength ratio of the product to reach 3:1, meeting the requirements of high-pressure transportation. In addition, its semi cured state is easy to cut and lay, with a waste rate of only 4% -6%, far lower than the 15% -20% of traditional wet forming, greatly reducing material waste.

5. Cost benefit advantages throughout the entire lifecycle

Although the initial procurement cost of Glass fiber prepreg is higher than that of traditional materials, the full lifecycle cost advantage is significant. In the field of industrial equipment, its corrosion resistance can extend the equipment maintenance cycle from 6 months to 24 months, reducing maintenance costs by 60%; In the field of new energy, the use of Glass fiber prereg for wind turbine blades can increase power generation efficiency by 5% -8%, and a single 10MW wind turbine can generate an additional 1.2 million kWh of electricity per year; In the field of shipbuilding, the use of Glass fiber preprep reduces the number of coating processes by 3 compared to steel hulls, shortens the construction period by 30%, and reduces navigation fuel consumption by 15%. The recyclability of thermoplastic products further reduces raw material costs, with a performance retention rate of over 70% for recycled materials, which can be used to manufacture secondary structural components.

6. Application characteristics of safety and environmental protection

Glass fiber prepreg has good environmental friendliness in both production and use processes. The pre soaking process is adopted in the production stage to avoid VOC pollution caused by resin volatilization during wet molding, reducing harmful substance emissions by more than 80%; During the usage phase, flame retardant products do not release toxic gases during combustion and comply with EU environmental standards such as EN45545; In the recycling stage, thermoplastic products can be recycled through melting and reshaping, while thermosetting products can be crushed and reused as fillers, in line with the green manufacturing trend under the "dual carbon" goal. In the field of electronic devices, its excellent electrical insulation can also reduce electromagnetic radiation and improve usage safety.

Process selling point: Precise control and value enhancement from raw materials to finished products.

The excellence of Glass fiber prepreg lies in its precise production process and full process quality control. Its process system not only ensures product consistency, but also achieves an optimized balance between performance and cost, becoming the core support of product competitiveness.

• 1. Core production process: Dual guarantee of hot melt method and solution impregnation method. The mainstream industry adopts two core impregnation processes, which can be flexibly selected according to product positioning and quality requirements to ensure the stability of the performance of Glass fiber prepreg
• 2.Hot melt process: Heat the resin to 80-120 ℃ to reduce viscosity, evenly coat the resin on the surface of the glass fiber through a precision hot press roller, and then rapidly cool it to room temperature through a cooling roller to complete semi curing and shaping. The core advantage of this process is the absence of solvent residue, precise control of resin content up to ± 0.5%, and high consistency of fiber arrangement, making it particularly suitable for the production of high-end Glass fiber prepregrades for aerospace applications. HexPy from Hexcel Corporation ® All series of products adopt this process, which controls the pressure (0.8-1.2MPa) and speed (5-10m/min) of the hot press roller through computer control, ensuring that the resin distribution error per square meter of product is less than 0.3%.
• 3.Solution impregnation process: The resin is dissolved in organic solvents such as acetone and ethanol to form a low viscosity solution. After the glass fiber fully adsorbs the resin in the impregnation tank, the solvent is evaporated through a multi-stage hot air drying channel (temperature gradient 50-120 ℃), and finally a semi cured state is formed. This process equipment has low investment cost and high production efficiency (with a line speed of up to 15-20m/min), making it suitable for large-scale production of general-purpose Glass fiber preforms. To solve the problem of solvent residue, the industry has widely adopted vacuum assisted removal technology, which reduces the residual solvent content to less than 0.1% and avoids bubbles and delamination defects after product solidification.
• 4.Key process control points: The five core processes that determine performance, such as the quality stability of Glass fiber preform, stem from the refined control of the entire production process. Among them, the five key processes directly determine the final performance of the product:
• 5.Surface treatment of glass fiber: The surface activity of the fiber is increased by oxidation treatment, and then coated with silane coupling agent to enhance the interfacial bonding strength between glass fiber and resin. After treatment, the interface peel strength increased by more than 40%, effectively solving the delamination problem that traditional products are prone to. After this treatment, the impact resistance of S-2 glass fiber based preprepregel can be improved by 35%.
• 6.Resin formula precise modulation: According to the functional requirements of the product, the resin, curing agent, additives and other ingredients are accurately proportioned. For example, flame-retardant products require the addition of 15% -20% phosphorus nitrogen flame retardants, along with 0.5% anti drip agents; For high-temperature resistant products, the molar ratio of epoxy resin to curing agent needs to be adjusted to 1:1.05 to ensure crosslinking density. The formula is prepared using a fully automatic mixing system, with an error controlled within ± 0.1%.
• 7.Dynamic control of impregnation parameters: Real time adjustment of impregnation speed, temperature, and pressure based on the specifications of glass fiber bundles and resin viscosity. For example, the impregnation speed of 1K filament bundle products is controlled at 8-10m/min, and the pressure is reduced to 0.6MPa to avoid fiber breakage; The 12K coarse fiber bundle product can be increased to 15m/min, and the pressure can be increased to 1.0MPa to ensure sufficient resin infiltration.
• 8.B-stage curing precise control: By adjusting the drying temperature and time, the resin curing degree is controlled at a semi cured state of 30% -40%, ensuring that the product has a certain viscosity for easy layering and avoiding premature complete curing. Real time monitoring of curing degree using differential scanning calorimetry (DSC) with an error of less than 2%.
• 9.Strict quality inspection of finished products: Each batch of products needs to pass multiple tests, including resin content (accuracy ± 0.1%), fiber surface density (± 2g/㎡), tensile strength, flame retardant performance, etc. The computer vision system is used to detect the uniformity of fiber arrangement, with a defect detection rate of 99.9%, ensuring that unqualified products do not enter the market.
• 10.Trend of process innovation: Three major directions to promote category upgrading. The industry continues to improve the performance and cost-effectiveness of Glass fiber prepreg through process innovation, and the three major innovation directions lead category development:
• 11.Upgrade of automated production line: Introduce industrial robots and AI control systems to achieve full process automation from glass fiber unwinding, impregnation, curing to coiling, increasing production efficiency by more than 50% and reducing product consistency error to ± 0.3%. For example, the automated production line of a leading enterprise can achieve a daily output of 5000 square meters per line, which is three times higher than traditional manual production lines.
• 12.Breakthrough in Multi axial Layering Technology: Developed a multi axial Glass fiber prereg production line that can simultaneously achieve synchronous impregnation of fibers in multiple directions such as 0 °, 90 °, ± 45 °, reducing subsequent product layering processes and increasing production efficiency by 40%. It is particularly suitable for the manufacturing of large components such as wind turbine blades and ship hulls.
• 13.Green process research and application: Promote solvent-free impregnation process and the application of bio based resins (such as plant-based epoxy resins) to reduce dependence on petroleum based raw materials. At the same time, develop chemical recycling technology for thermosetting products to increase the recycling rate to over 60%, which is in line with the trend of green manufacturing and circular economy.