Thermosetting resins like epoxy are used for their rigidity and heat resistance, but can be brittle, crack, delaminate, and are difficult to process due to internal stresses from curing and thermal history.
S-LEC™ BK Series from SEKISUI Specialty Chemicals is a PVB-based modifier for thermosetting resins. Its structure boosts toughness, adhesion, and processability while allowing formulation flexibility.
For more detailed information and evaluation guidance, please download the data sheet.
Thermosetting resins provide strong mechanical strength and thermal stability. However, curing shrinkage and thermal history generate internal stress, leading to cracking, fracture, and interfacial delamination.
These issues are particularly significant in applications such as electronic materials, adhesives, composites, and filler-filled systems, where not only post-cure toughness and adhesion, but also viscosity and handling during processing—such as coating, impregnation, and molding—are critical factors.
To overcome such processing and performance challenges, rubber-based modifiers are often used to improve toughness, though they may affect modulus or overall property balance depending on formulation conditions. As a result, there is increasing demand for modification approaches that enhance toughness, adhesion, and processability without significantly altering existing formulations.
S-LEC™ BK Series uses its flexible molecular backbone and polar functional groups in PVB to boost the performance of thermosetting resins. When you add it to a formulation, it absorbs and dissipates internal stress during curing, reducing the risk of cracks forming and spreading.
Hydroxyl groups strengthen interfacial interactions with the matrix resin and fillers, improving adhesion. By adjusting molecular weight and functional group composition, you can tailor solubility, viscosity, and modification effects to your application. Start by evaluating the material at low addition levels—this makes performance assessment simple without major formulation changes.
To effectively use S-LEC™ BK Series as a PVB modifier, identify your key property targets and match them with considerations such as the thermosetting resin, solvent system, addition level, curing conditions, processing temperature, and required balance of toughness, modulus, adhesion, and viscosity. If minimizing internal stress is the main goal, select grades with high stress-relaxation potential. For critical adhesion, prioritize evaluating interfacial interactions provided by polar functional groups.
For tailored material selection and evaluation support from SEKISUI Specialty Chemicals, please share your specific application, formulation details, and targeted properties.
Q. What applications are suitable for S-LEC™ BK Series?
A. It can be considered for thermosetting resin systems such as epoxy where improvements in brittleness, cracking, adhesion, or processability are required. Typical applications include electronic materials, adhesives, composites, and filler-filled systems. Suitability depends on resin type, solvent, curing conditions, and target properties.
Q. What benefits can I expect by adding S-LEC™ BK series?
A. The flexible molecular structure of PVB absorbs and dissipates internal stress during curing, which may reduce cracks. Polar functional groups enhance interfacial interactions with resins and fillers, improving adhesion.
Q. What is the difference between the S-LEC™ BK Series and rubber-based modifiers?
A. Rubber-based modifiers can provide toughness, but may lower elastic modulus. PVB maintains elasticity better than rubber-based modifiers. The balance of physical properties depends on formulation and dosage, so individual evaluation is needed.
Q. Can I evaluate S-LEC™ BK Series without major formulation changes?
A. Yes. S-LEC™ BK Series can be tested at low levels without major formulation changes. Always confirm compatibility and solubility for each system.
Q. What should I check when selecting a grade?
A. Review key factors: resin type, solvent system, addition level, curing conditions, processing temperature, and target properties. Then, identify your most important performance requirements—such as toughness, modulus, adhesion, or filler interaction—to select the appropriate grade.
Q. What information should I share to start the evaluation?
A. To begin the evaluation, please share details such as target resin, solvent system, current formulation, curing conditions, processing temperature, purpose of modification, and desired properties. Be sure to specify your key priorities—such as toughness, modulus, adhesion, or viscosity—to help you streamline material selection and evaluation design.
