PAN-Based Carbon Fiber Impregnation Prepreg Machine Line System

  • Thermoset resin:epoxy/phenolic/BMI
  • Thermoplastic resin:PA/PPS/PEEK/PET/PC
  • A long-term partner of aviation companies
  • Leading hot-melt prepreg system
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Jota Hot-Melt Thermoset/Thermoplastic Prepreg Machine

Our continuous fiber-reinforced polymer prepreg machines are ideal machines for composite material production in aerospace,automotive, hypercar, etc.

Prepregs are essential raw materials for the production of high-performance carbon fiber and glass fiber composite materials.They can be divided into two types: thermoplastic and thermoset.

If you are looking for prepreg machines, please send us an inquiry on this website.

Jota Machinery: Your Reliable CFRTP CFRP Prepreg Machine Manufacturer in China

Jota is the original CFRT/CFRP prepreg machine manufacturer here in China.

With our own factory and CNC center, equipment quality could be effectively guaranteed.

Please send us an inquiry to make a WhatsApp video call, let’s show you our real-time factory and CNC center.

Jota-CNC-Machine

Jota CNC Center

Machining Material

  • Visible high-quality components.
  • Famous brands such as Siemens, Yaskawa, Delta, Schneider, Mitsubishi.
  • Self-supporting CNC processed sheet metal, precision parts.
  • Assembly raw materials provided by long-term cooperation suppliers.
Installation and Operation

Installation and operation user manual, wire connection diagram, tension controller guide.

Installation and operation video tutorial.

One-on-one remote video call assistance.

On-site installation and operation guidance.

FAQ
What's the delivery time?

Around 30-45 days, mainly depends on machine type.

Could you help us to buy other goods?

Sure, it is our honor to work for you.

If the machine's spare parts are broken, where could I get?

We will offer you some parts as backup, in case any part is broken within one year, we will sent you for free.

Could you tell us your client’s contact for us to checking machine on site?

Sure, if we have client in your country, we will offer.

Contact Our Support Team

Unveiling the Art and Science of PAN-Based Carbon Fiber Production: From Polymerization to Advanced Prepreg Machine

Carbon fiber is a high-strength and high-modulus, high-temperature-resistant fiber, which is a high-end variety of chemical fibers.

Carbon fiber is made from specially treated high-quality polyacrylonitrile (PAN).

PAN-based carbon fiber typically consist of 1000 to 48,000 carbon filaments, each filament having a diameter of 5-10μm, and they exhibit a microcrystalline graphite structure.

carbon fiber roving

To produce carbon fiber roving, carbon atoms are bonded together in crystals, and the parallel alignment of fiber long axes gives carbon fibers a high strength-to-volume ratio.

Thousands of carbon fiber are bundled together to form a fiber bundle, which can be used individually or woven fabric.

Major manufacturers of PAN-based carbon fibers include Japanese companies such as Toray, Toho, Mitsubishi Rayon, and American companies like Hexcel, Amoco, and Zoltek.

toray carbon fiber

Among them, three Japanese companies, Toray, Teijin, and Mitsubishi Rayon, are prominent manufacturers of PAN-based carbon fibers, accounting for over 75% of the world’s carbon fiber market.

The production process of PAN-based carbon fiber

Polyacrylonitrile-based carbon fibers (PAN-based carbon fibers) account for over 90% of carbon fiber production worldwide.

Since their introduction in the 1960s, they have undergone significant development and have become the mainstream of today’s carbon fiber industry.

The production process of PAN-based carbon fibers mainly consists of three stages: the first stage is polymerization, in which purified materials react to prepare spinning solution.

thermoset prepreg

The second stage is spinning, where qualified spinning solution is extruded through a spinneret to form PAN precursor fibers

The third stage is pre-oxidation and carbonization of precursor fibers, turning them into carbon materials with a carbon content of over 90%.

Polymerization

Polymerizing PAN-based carbon fibers generally involves copolymerization of acrylonitrile and a second monomer.

This method produces precursor fibers that undergo ion-type reactions during pre-oxidation, which are easier to control, and the pre-oxidation process requires lower temperatures.

Common copolymerization monomers include acrylic acid, itaconic acid, maleic acid, acrylamide oxime, etc.

To prepare high-performance carbon fibers, all raw materials must be purified before use.

Polymerization is the first step in preparing precursor fibers, and high-quality polymerization solution is a prerequisite for preparing high-performance precursor fibers.

carbon fiber production factory

After polymerization, it is necessary to remove monomers and bubbles.

High-quality polymerization solution must meet the following conditions: appropriate molecular weight and molecular weight distribution, suitable viscosity, appropriate solid content, minimal unreacted monomers, minimal bubbles, etc.

Polymerization methods include solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization, with solution polymerization being the most widely used in industry.

Common solvents used in solution polymerization include N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), nitric acid (HNO3), sodium thiocyanate (NaSCN) solution, and zinc chloride (ZnCl2) solution.

DMF can produce high-quality carbon fibers, but it is toxic.

The nitric acid method has poor safety and serious pollution.

The sodium thiocyanate method and the zinc chloride method have a significant impact on the quality of carbon fibers due to sodium and zinc ions, making it difficult to produce high-quality carbon fibers.

The manufacturing process using DMSO as a solvent is technically mature, with stable product quality, and is recognized domestically and internationally as the most advanced process.

Spinning

Spinning is the process of separating the polymerization solution into fibers, involving heat and mass transfer between the polymerization solution and the coagulant.

After being extruded from the spinneret, the filaments go through steps such as coagulation bath, water washing, hot water stretching, oiling, steam drawing, and heat setting to become PAN precursor fibers.

The temperature and concentration of the coagulation bath (including the concentrations of DMSO and NH3), the stretching ratio, circulation volume, etc., are crucial for the properties of the primary fibers.

The performance indicators of the primary fibers mainly include cross-sectional shape, number of micropores, crystallinity, strength, orientation, etc.

Changing the temperature and concentration of the coagulation bath can adjust the rate of double diffusion to obtain primary fibers with circular cross-sections, dense structures, and high strength.

pan fiber

Any non-circular cross-section precursor fiber will generate stress and heat concentration during subsequent pre-oxidation and carbonization processes, affecting the performance of carbon fibers.

After passing through the coagulation bath, the primary fibers need to be washed with water to remove residual solvents from the filaments, avoiding fusion between individual filaments during pre-oxidation, which would affect the quality of carbon fibers.

Stretching is the most important means to improve fiber orientation.

During stretching, the orientation of the fiber network increases, greatly enhancing its strength.

In the coagulation bath, the fiber needs to be negatively stretched to reduce filament breakage, while in other processes (except for heat setting), it needs to be positively stretched to increase orientation. The total stretching ratio is generally between 5-8 times.

The purpose of oiling is to increase the bundling of fibers, reduce filament adhesion and antistatic properties, and the oil also contributes to increasing the strength of carbon fibers by about 0.5-1.0 GPa.

Currently, most high-performance precursor fibers use silicone-based oils.

Fibers undergo multiple stretching steps before oiling, resulting in internal stresses and an unstable state, so they must undergo relaxation heat setting to relax the local segments and maintain the preferred orientation of the entire macromolecular chain to the fiber axis.

Pre-oxidation and Carbonization

PAN precursor fibers need to undergo pre-oxidation and carbonization before becoming carbon fibers.

The purpose of pre-oxidation is to transform the linear molecular chains of PAN into heat-resistant ladder structures, so that they do not melt or burn during high-temperature carbonization, maintaining their fibrous state.

Carbonization process

Currently in industrial production, PAN precursor fibers are pre-oxidized in an air oxidation furnace with a temperature gradient of 160-300°C, then low-temperature carbonized in high-purity nitrogen at 300-800°C, and finally high-temperature carbonized at 1300-1600°C.

Carbonization oven
Carbonization Oven

Carbonization is the main stage of carbon fiber formation, during which a large amount of hydrogen, nitrogen, and other elements are removed, increasing the carbon content to over 90%.

In the pre-oxidation and carbonization process, temperature and its distribution gradient, oxidation and carbonization time, tension drawing, and other process parameters need to be considered.

To prepare high-modulus graphite fibers, the already carbonized carbon fibers need to undergo ultra-high-temperature graphitization in an argon atmosphere, at around 2600-3000°C.

Carbon fibers are generally not used alone but as reinforcement in composite materials.

The prepreg machine provided by Jota Machinery can provide an impregnation process for continuous carbon fibers and resin polymers.

Our equipment is distinguished into thermosetting and thermoplastic types.

Thermoset prepreg machine system

The hot melt thermoset prepreg machine line system consists of two units:

Prepreg epoxy resin coating machine

The epoxy resin is placed on the heating plate of the coating machine and heated to 60-80 degrees Celsius, at which point the epoxy melts into a liquid.

epoxy resin

On our 1300mm coating machine, there are two rollers: one is direction-fixed, and the other roller is used to transfer epoxy resin onto the release paper, forming a reverse roller coating process.

Simultaneously, our thickness scanner detects the thickness of the coating in real-time and displays it on the touchscreen.

The PE film and the coated release paper form a resin film also called filmer.

Compounding machine

After the production of the resin film, it is placed on the compounding prepreg machine, with one roll on each of the upper and lower layers.

One of the 3-inch air expanding shafts is used to remove the PE film from the filmer, while another is used to place the resin film.

Unidirectional prepreg material and woven carbon fiber fabric can be prepared into thermosetting prepreg rolls through continuous hot pressing, cooling, laminating, and rewinding processes.

Processes Related to thermoset prepregs.

Common forming processes for prepreg materials mainly include autoclave, automated fiber placement (AFP), prepreg compression molding processes, and hydrogen storage cylinder filament winding.

Autoclave

An autoclave is a pressure vessel that provides curing conditions for composite materials by controlling various parameters such as vacuum, pressure, heating rate, and curing temperature.

Like vacuum bagging technology, autoclave curing involves placing carbon fiber prepreg tape materials in a vacuum bag inside the autoclave, evacuating the air with a vacuum pump, and then curing them through a controlled heating process.

This forming technology is stable and reliable, with a wide range of applications, suitable for manufacturing military aircraft radar domes, fairings, aircraft cabin doors, wings, and other products.

Automated Fiber Placement (AFP) Technology

Automated fiber placement (AFP) technology utilizes laying heads to form several bundles of prepreg fibers or dry fiber tows into a tape with variable width.

With the aid of flexible pressure rollers and auxiliary heating devices, the tape is laid onto the surface of the mold to achieve heating, compaction, and shaping, representing an automated composite material forming technology.

AFP uses carbon fiber uni-directional (UD) prepreg tapes with widths of 3.175mm or 3.2mm/6.35mm/12.7mm (also known as narrow prepreg tapes) as raw materials, enabling the simultaneous layup of concave and convex surfaces and meeting specific layup requirements such as local openings, area reinforcements, and adaptive boundaries.

afp towpreg
Automated Fiber Placement(AFP) 6.35mm Width Towpreg

Compared to automated tape laying (ATL) technology, AFP offers greater laying trajectory freedom, allowing continuous angle changes in laying.

This technology significantly enhances the automation of manufacturing complex curved components, resulting in higher product quality and lower costs.

Additionally, AFP has a lower waste rate (3%~8%), consumes fewer auxiliary materials, and greatly reduces labor intensity for workers, leading to rapid development in recent years.

AFP’s uni-direcrional tape preparation methods mainly include prepreg slitting.

Prepreg slitting involves precise cutting of wide carbon fiber prepreg tapes into narrow ones based on traditional prepreg materials.

The method enables precise control of resin content and tape width.

AFP MACHINE

However, achieving complete parallelism between the slitting blade and the fiber’s longitudinal direction is challenging, which may cause edge fraying or yarn breakage defects.

This method imposes high requirements on slitting rewinding machine.

Jota Machinery has extensive experience in cooperation with major universities and aerospace manufacturing companies and has outstanding slitting effects in prepreg material cutting processes.

towpreg spooling machine
Towpreg Spooling Machine in Aerospace Cooperation

Currently, it is assisting in the production of prepreg for COMAC C919.

Automated fiber placement is a highly automated process controlled entirely by a computer system.

To ensure the smooth progress of fiber placement processes, multiple parameters need to be controlled, including laying temperature, laying pressure, tension control, positioning of laying reference points, real-time adjustment and monitoring of various motion axes, program code correction, and other aspects.

Laying control software mainly consists of offline design programming software and laying motion control software.

Offline design programming software can establish mathematical models of laying components, plan laying paths, generate CNC code programs offline, parameterize CNC programming for equipment and materials, and provide built-in functions such as scrap analysis, processing time, and process optimization.

It also includes specific functions, such as local reinforcement wave laying, which can improve molding quality.

Motion control software automatically completes the laying process according to the instructions of the program code, including advancing motion, lifting motion, feed motion during the laying process, and control of various joint motions of the laying head unit.

It also automatically completes actions such as clamping, cutting, and refeeding of prepreg fiber tows, achieving the automated layering process of composite materials accurately and timely according to the set program code.

Prepreg compression molding process

A certain amount of prepreg material is placed into a metal mold and cured by heating and pressing.

Its main advantages lie in high production efficiency, high product dimensional accuracy, good repeatability, but complex mold manufacturing and high costs.

Hydrogen storage cylinder filament winding

Carbon fiber filament winding forming technology involves winding continuous carbon fibers (or fiber tapes, prepreg yarns) impregnated with resin adhesive onto a core mold in a certain pattern, followed by curing and demolding to obtain the final product.

According to the physical and chemical state of the resin matrix during carbon fiber winding forming, there are three processes:

Dry filament winding

Dry winding uses prepreg yarns or tapes treated with resin adhesive, which are softened by heating to a viscous state on the filament winding machine before being wound onto the core mold.

Since the prepreg yarn (or tape) is professionally produced, it can strictly control the resin content (within 2%) and the quality of the prepreg yarn.

Therefore, dry winding can accurately control product quality.

The major feature of dry winding technology is its high production efficiency, with winding speeds of up to 100~200m/min.

The dry filament winding machine is clean, with good labor hygiene conditions, and high product quality.

Its drawback is the expensive winding equipment, requiring additional prepreg yarn manufacturing equipment, resulting in a large investment. Additionally, the interlaminar shear strength of dry-wound products is relatively low.

Wet filament winding

Wet winding involves impregnating fiber bundles (yarn tapes) with resin adhesive and directly winding them onto the core mold under tension control.

The advantages of wet winding are:

  • 1) 40% lower cost than dry winding.
  • 2) good product airtightness, as the winding tension squeezes out excess resin adhesive, filling voids.
  • 3) good fiber alignment.
  • 4) during wet winding, resin adhesive on the fibers can reduce fiber wear.
  • 5) high production efficiency (up to 200m/min).

The disadvantages of wet winding are:

  • 1) high resin waste, poor operating environment
  • 2) difficulty in controlling resin content and product quality
  • 3) fewer resin varieties available for wet winding.

Semi-dry filament winding

Semi-dry winding involves adding a drying device midway through fiber impregnation to remove solvents from the impregnated yarn, eliminating the need for prepreg adhesive processes and equipment.

Compared to wet winding, it reduces the bubble content in the products.

Currently, carbon fiber composite pressure vessels are mainly used in:

  1. Medical respiratory systems, including home and medical oxygen respirators,
  2. Self-contained positive-pressure air respirators for firefighting and compressed oxygen circulating respirators for rescue,
  3. Aircraft escape slide inflation devices, ejection seats, shells, etc., in the aerospace field,
  4. New energy vehicle field, including steel-lined carbon fiber hoop-wrapped steel composite gas cylinders (CNG-2), aluminum-lined carbon fiber fully wound composite gas cylinders (CNG-3), plastic-lined fully wound composite gas cylinders (CNG-4), compressed natural gas storage cylinders, high-pressure hydrogen gas pressure vessels, etc.

Next, let’s turn to the topic of thermoplastic prepreg machine.

CFRT uni-directional prepreg tape refers to continuous fiber reinforced thermoplastic unidirectional tape made by impregnating continuous fibers with thermoplastic plastics.

The thermoplastic resins involved include PP, PA, PET, PC, PPS, PEI, and PEEK, while the fibers include glass fibers, carbon fibers, aramid fibers, etc.

peek

These products can be stored for a long time and maintain good mechanical properties under high temperature and high humidity.

There are multiple forming methods with high production efficiency, and demand has grown rapidly in recent years.

Thermoplastic prepreg machine

The production process of thermoplastic prepreg materials is different from that of thermosetting prepreg materials and requires only one pre-impregnation equipment.

High-performance plastic resins are uniformly placed in a hopper and extruded into a liquid state through twin-screw or single-screw extrusion to compound with continuous fibers.

thermoplastic prepreg machine

Cooling and rewinding form unidirectional thermoplastic prepreg tapes. This process is called hot melt extrusion impregnation.

Whether it is thermoplastic prepreg machine or thermosetting prepreg, Jota Machinery produces them through hot melt methods.

The preparation methods for producing unidirectional thermoplastic tapes include powder impregnation, solution methods, etc.

Compared to other methods, thermoplastic prepreg prepared by hot melt extrusion impregnation exhibits excellent molding and strength properties, suitable for various shapes and sizes of plates and profiles.

If you would like to learn more about our prepreg machine equipment, please feel free to contact us.

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