Views: 0 Author: Site Editor Publish Time: 2026-11-10 Origin: Site
Release film is an essential consumable in composite manufacturing. It provides a separation layer between the composite laminate and other vacuum bagging materials, while helping control resin flow during curing. However, selecting the right release film involves more than choosing a film based on its maximum temperature rating.
Different resin systems have different curing characteristics, viscosities, chemical compositions and processing requirements. Epoxy, polyester, vinyl ester, phenolic and BMI resins may require different release film specifications, particularly when processing temperatures and resin management requirements vary.
Choosing an unsuitable release film can lead to poor release performance, film deformation, excessive resin loss or difficulties during demoulding.
For composite manufacturers, understanding the relationship between resin chemistry, curing conditions and release film performance is essential for achieving consistent production quality.
In this guide, JLON explains how to select the appropriate release film for different composite resin systems, including practical considerations for vacuum infusion, vacuum bagging and high-temperature composite curing.
Release film is not simply a protective plastic layer. During composite manufacturing, it is exposed to resin, heat, pressure and vacuum throughout the curing process.
Its performance depends on several interacting factors.
Different thermosetting resins have different chemical structures and curing mechanisms.
Although many release films are designed to separate easily from cured composite materials, their performance may vary depending on the resin formulation and processing conditions.
Important considerations include:
· Whether the film maintains its physical integrity during resin contact.
· Whether the resin adheres to the film after curing.
· Whether the film surface provides consistent release performance.
· Whether the film is affected by the resin formulation or processing additives.
A release film that performs well with one epoxy formulation may not necessarily deliver identical results with another resin system.
Temperature resistance is one of the most important factors in release film selection.
However, the maximum temperature alone does not determine suitability. The complete curing cycle must also be considered, including:
· Maximum laminate temperature.
· Heating rate and temperature profile.
· Curing duration and holding time.
· Resin exotherm.
· Applied pressure and vacuum conditions.
For example, an epoxy resin cured at 120°C and a high-performance epoxy system cured at 180°C require different release film solutions.
The release film must maintain its mechanical properties and release characteristics throughout the actual curing cycle, not simply tolerate a short exposure to the specified temperature.
The resin management strategy also affects film selection.
In composite manufacturing, some processes require excess resin to be removed, while others are designed to retain the resin within the laminate.
This determines whether perforated or non-perforated release film is appropriate.
· Perforated release film: Allows resin to pass through designated openings under suitable processing conditions.
· Non-perforated release film: Provides a continuous barrier to resin transfer and is commonly used when resin retention is required.
The correct configuration depends on resin viscosity, laminate design, pressure, temperature and the complete consumable arrangement.
Different resin systems require different considerations. The following sections explain the main factors affecting release film selection.
Epoxy resin is widely used in structural composites because of its mechanical strength, adhesion properties and chemical resistance.
It is commonly found in aerospace components, carbon fiber structures, wind energy applications, sporting goods and high-performance industrial composites.
Epoxy resin systems cover a broad range of curing temperatures.
Depending on the formulation, they may be processed through:
· Room-temperature curing.
· Elevated-temperature oven curing.
· Vacuum bagging and post-curing.
· Autoclave curing of epoxy prepregs.
High-performance epoxy prepregs may require curing temperatures of 120°C, 180°C or higher, depending on the material specification.
For lower-temperature epoxy processes, conventional PE-based or PP-based release films may be suitable, provided that their temperature ratings and resin compatibility have been verified.
For example:
· JLON JL-RF130: Modified PE release film, with a maximum specified service temperature of 130°C.
· JLON JL-RF160: PP/PE/PA6-based release film, with a maximum specified service temperature of 160°C.
For elevated-temperature epoxy prepreg curing and autoclave applications, high-temperature release films should be considered.
JLON provides two fluoropolymer-based options:
· JL-RF230 ETFE Release Film: Recommended working temperature up to 210°C.
· JL-RF260 FEP Release Film: Recommended working temperature up to 240°C.
These recommendations are subject to the actual curing duration, temperature exposure and processing conditions.
The choice depends on the epoxy processing method.
For prepreg systems requiring controlled resin bleed, perforated release film can allow excess resin to pass into an appropriate bleeder material.
For no-bleed prepreg systems, non-perforated release film is generally more appropriate because it helps retain the designed resin content.
For vacuum infusion using liquid epoxy resin, perforated release film may also be used in selected lay-up configurations to facilitate resin transfer while separating the laminate from the flow media.
Unsaturated polyester resin is widely used in fiberglass reinforced plastic (FRP) manufacturing.
Typical applications include boat hulls, tanks, pipes, automotive components, building materials and industrial composite panels.
Polyester resin is commonly cured at room temperature or under moderate heating.
Its curing process involves a chemical reaction initiated by a suitable catalyst or initiator system.
During curing, the resin viscosity changes as the reaction progresses, eventually forming a rigid thermoset structure.
The actual curing temperature depends on the resin formulation, catalyst concentration, component thickness and production conditions.
For conventional polyester resin applications, modified PE or other suitable polymer-based release films may be considered.
JLON JL-RF130 can be evaluated for polyester composite processes with curing temperatures within its specified service range.
For processes requiring higher thermal resistance, JL-RF160 may be considered, subject to validation.
In fiberglass vacuum infusion and controlled resin transfer processes, perforated release film can be useful when resin needs to pass through the separation layer.
For applications where resin retention is important, non-perforated release film provides a more suitable barrier.
For example, during the manufacturing of FRP boat hulls, the release film configuration should be selected according to the infusion arrangement, resin distribution strategy and required laminate properties.
Vinyl ester resin is commonly used in applications requiring improved corrosion resistance, chemical resistance and mechanical performance.
Typical applications include chemical storage tanks, industrial pipes, marine structures and corrosion-resistant FRP equipment.
Vinyl ester resin is a thermosetting resin with curing characteristics similar to unsaturated polyester systems.
However, its chemical formulation and curing behavior differ.
The viscosity, gel time and exothermic behavior depend on the specific resin grade and curing formulation.
For thicker laminates, local temperature increases caused by resin exotherm should also be considered.
Conventional release films may be suitable for many standard vinyl ester processes, provided that they maintain their integrity during resin contact and curing.
JLON JL-RF130 and JL-RF160 can be evaluated according to the actual process temperature and resin formulation.
For higher-temperature processing, an appropriate high-temperature release film may be required.
For vacuum infusion and controlled resin transfer, perforated release film can help regulate resin passage between the laminate and distribution media.
The selected perforation pattern should be evaluated together with resin viscosity, vacuum conditions and the required resin flow.
It is important not to assume that a perforation pattern suitable for polyester resin will automatically provide identical results with vinyl ester resin.
Phenolic resin is used in composite applications where fire performance, smoke characteristics and thermal resistance are important.
Typical applications include railway interiors, aerospace components, fire-resistant panels and industrial insulation products.
Phenolic resin systems may involve more demanding processing conditions than conventional polyester and vinyl ester systems.
Depending on the formulation, processing may require elevated temperatures and carefully controlled curing cycles.
The release film must withstand the complete thermal exposure without losing its mechanical integrity or release properties.
For phenolic resin processing, release film selection should begin with the resin manufacturer's curing schedule.
Conventional PE-based release films should not be selected solely because they are compatible with other thermosetting resins.
For elevated-temperature applications, high-temperature ETFE or FEP release films may be considered.
JLON JL-RF230 and JL-RF260 are potential options for evaluation, depending on the actual curing temperature and exposure duration.
Phenolic resin systems may have specific requirements relating to volatile release and resin flow.
Therefore, the selection of perforated or non-perforated release film should be coordinated with the overall vacuum bagging arrangement.
A production trial is recommended before changing the release film in an established phenolic composite process.
Bismaleimide (BMI) resin is a high-performance thermosetting resin used in aerospace and other demanding applications.
It is valued for its elevated-temperature performance and is commonly used in advanced composite structures.
BMI prepregs may require elevated-temperature curing cycles, depending on the formulation.
The process can involve high temperatures, controlled pressure and extended curing or post-curing procedures.
As a result, release film selection requires particular attention to thermal stability and mechanical properties.
High-temperature fluoropolymer release films are potential candidates for BMI processing.
JLON JL-RF230 ETFE release film and JL-RF260 FEP release film can be evaluated according to the specified curing cycle.
The choice between these materials should consider:
· Maximum laminate temperature.
· Total exposure duration.
· Mechanical strength and film handling requirements.
· Part geometry and surface conformity.
· Release performance with the specific BMI formulation.
For particularly demanding processes, material compatibility should be confirmed through representative curing trials.
The following table provides a general selection reference for common composite resin systems.
Resin System | Typical Applications | Main Selection Considerations | Potential Release Film |
Epoxy | Carbon fiber, aerospace, wind energy | Curing temperature, resin bleed, prepreg requirements | PE, PP/PE/PA6, ETFE, FEP |
Polyester | FRP boats, tanks, panels | Resin flow, curing temperature, infusion arrangement | Modified PE, PP-based |
Vinyl Ester | Chemical tanks, pipes, marine FRP | Chemical formulation, exotherm, resin transfer | Modified PE, PP-based, high-temperature grades where required |
Phenolic | Railway, fire-resistant panels, aerospace | Thermal exposure, volatiles, resin flow | ETFE, FEP subject to validation |
BMI | Aerospace, high-performance composites | High-temperature curing, pressure, exposure duration | ETFE, FEP subject to validation |
Note: The materials listed are potential candidates, not universal compatibility guarantees. Final selection must be based on the specific resin formulation, film grade and complete manufacturing process.
Even when the resin system is known, several additional factors can influence release film performance.
The perforation configuration determines whether resin can pass through the film.
Perforated release film is commonly used in applications requiring controlled resin bleed or resin transfer.
JLON offers different perforation options, including P3, P6 and P16 configurations for relevant grades.
The actual hole diameter, spacing and distribution should be confirmed before ordering because perforation codes can vary between suppliers.
Non-perforated release film provides a continuous separation layer.
It is suitable for applications where resin retention is required and uncontrolled resin transfer must be prevented.
For no-bleed prepreg processing, non-perforated film may be appropriate, provided that the overall system provides suitable air and volatile evacuation paths.
Release film thickness influences handling, flexibility and resistance to damage during lay-up.
Thin films can conform more easily to complex geometries, while thicker films may provide improved handling strength depending on the material.
However, thickness alone does not determine film performance.
Tensile strength, elongation, tear resistance and dimensional stability should also be considered.
The manufacturing process can significantly affect release film selection.
For example:
· Vacuum infusion requires consideration of resin flow and the position of the release film within the consumable stack.
· Vacuum bagging requires suitable film integrity under vacuum and pressure.
· Autoclave curing requires the film to withstand the specified temperature and pressure throughout the cycle.
· Oven curing requires consideration of temperature distribution and curing duration.
A release film suitable for one process should not automatically be assumed suitable for another.
JLON supplies release film solutions for different composite manufacturing processes, including conventional vacuum bagging, resin infusion and high-temperature composite curing.
Rather than recommending a film based on resin type alone, JLON considers the complete manufacturing process.
JLON conventional release films include:
· JL-RF130: Modified PE, 35 μm nominal thickness, maximum specified service temperature of 130°C.
· JL-RF160: PP/PE/PA6-based, 40 μm nominal thickness, maximum specified service temperature of 160°C.
Both grades are available in perforated and non-perforated configurations.
They can be evaluated for epoxy, polyester and vinyl ester composite manufacturing processes, depending on the specific resin formulation and curing conditions.
For demanding composite curing applications, JLON provides fluoropolymer-based release film options.
· JL-RF230 ETFE: 25 ± 5 μm nominal thickness, recommended working temperature up to 210°C.
· JL-RF260 FEP: 25 ± 5 μm nominal thickness, recommended working temperature up to 240°C.
These films are designed for evaluation in selected high-temperature prepreg, autoclave and composite molding applications.
Both perforated and non-perforated options are available, subject to grade configuration.
For more information, visit:
· JLON Release Film for Composite Vacuum Bagging and Resin Infusion
· JLON High-Temperature Release Film for Composite Curing
Different composite manufacturers may require different film widths, roll lengths, thicknesses and perforation configurations.
JLON can discuss suitable specifications according to the customer's production requirements.
To help identify an appropriate release film, customers are encouraged to provide:
1. Resin type and specific resin grade.
2. Maximum curing temperature and total curing duration.
3. Manufacturing method, such as vacuum infusion, vacuum bagging or autoclave curing.
4. Required resin bleed or resin retention characteristics.
5. Preferred film thickness and roll dimensions.
6. Required perforation pattern, if applicable.
Where necessary, sample testing under actual production conditions is recommended before full-scale implementation.
In many cases, yes. Certain release film grades can be evaluated with multiple resin systems.
However, compatibility with one resin formulation does not guarantee identical performance with another.
Processing temperature, curing duration, resin chemistry and resin flow requirements must all be considered.
Neither material is universally better.
ETFE generally offers relatively high mechanical strength and toughness, while FEP provides a higher recommended working temperature in the JLON product range.
JL-RF230 ETFE is recommended for working temperatures up to 210°C, while JL-RF260 FEP is recommended up to 240°C.
The final choice should depend on the actual curing cycle, mechanical requirements and resin compatibility.
Yes, suitable PE-based release films can be used in certain epoxy composite processes.
For example, JLON JL-RF130 is a modified PE release film with a specified maximum service temperature of 130°C.
It should only be used when the complete curing cycle falls within its verified operating limits.
For higher-temperature epoxy curing, a more heat-resistant film should be considered.
The choice depends on the resin flow arrangement.
Perforated release film may be used when resin needs to pass through the separation layer to reach the distribution media.
Non-perforated release film may be appropriate when a continuous resin barrier is required.
The final configuration should be determined by the complete infusion stack and resin distribution design.
The most reliable method is to evaluate the film using the actual resin formulation and curing cycle.
A practical trial should check whether the film maintains its integrity, releases properly after curing and provides the required resin flow or retention.
JLON can help review the process information and recommend suitable samples for evaluation.
Selecting the right release film for composite manufacturing requires more than matching the film to a resin category.
Resin chemistry, curing temperature, exposure duration, resin bleed requirements, vacuum pressure and component geometry all influence the final choice.
For conventional epoxy, polyester and vinyl ester applications, suitable PE or PP-based release films may provide a practical solution. For elevated-temperature epoxy, phenolic and BMI composite processing, high-temperature ETFE or FEP release films may be more appropriate, subject to process validation.
JLON provides conventional and high-temperature release film solutions for composite manufacturers, with different materials, thicknesses and perforation configurations.
Whether you manufacture fiberglass boat hulls, wind turbine components, carbon fiber structures or high-performance aerospace composites, selecting the correct release film can help improve process consistency and production reliability.
