With the launch of the IGF research project “KombiHaft,” the SKZ Plastics Center and the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research (IFAM) are pooling their complementary expertise to rethink one of the key challenges in plastics processing: the reliable and cost-effective coating of polyolefins.
“KombiHaft” Research Project Launches: New Approaches to Creating Paint-Friendly Polyolefin Surfaces in Injection Molding
Polyolefins such as polypropylene and polyethylene are indispensable in industrial production due to their excellent mechanical properties, low cost, and comparatively good carbon footprint.
At the same time, their nonpolar surfaces pose a significant hurdle for subsequent painting and coating processes. In practice, this has so far led to cost-intensive pretreatment methods that are the subject of environmental debate, or even to material substitutions that entail both economic and sustainability-related drawbacks.
This is precisely where the “KombiHaft” project comes in—with the clear goal of significantly improving the paintability of polyolefins directly within the injection molding process and thereby fundamentally streamlining existing process chains.
Material Innovations Meet Process Intelligence
The project’s innovative approach is based on the targeted combination of two solution spaces that have previously been considered separately: material-based functionalization and mold-based process control.
At Fraunhofer IFAM, novel photoreactive adhesion promoters are being developed that selectively accumulate on the component surface during the injection molding process. Through subsequent UV activation, these are stably fixed in the form of molecularly thin layers, thereby enabling improved paintability of polyolefin surfaces—without additional wet chemical or thermal pretreatment steps.
In doing so, known critical classes of substances are deliberately avoided; instead, the focus is on thermally stable, cost-effective, and toxicologically safe molecular designs.
In parallel, the SKZ is developing mold design strategies that specifically influence the boundary layer structure of the component. The focus is on innovative concepts for active and passive surface temperature control—for example, through ceramic heating systems or functional mold coatings—as well as biomimetic-inspired microstructuring of the mold surface.
These measures directly affect the molding and cooling behavior and thus the molecular and morphological characteristics of the component surface—key control variables for the resulting adhesion in subsequent painting and coating processes.
“With ‘KombiHaft,’ we are taking a holistic approach for the first time, in which material chemistry and process control are not considered in isolation but are specifically linked,” explains Dr. Martin Wiesing, project manager at Fraunhofer IFAM. “It is precisely this systematic coupling that opens up the possibility of adjusting adhesion properties in a reproducible and industrially robust manner.”
Inline Activation as the Key to a Process Revolution
A key objective of the project is to integrate the activation of the plastic surface directly into the ongoing injection molding process. The adhesion promoters are introduced as additives, migrate in a controlled manner to the component surface, and are activated by UV radiation immediately after molding.
This inline approach promises a paradigm shift: time-consuming process steps that must be adapted to the surface of the supplied component—such as flame treatment, plasma activation, or primer application—could be completely eliminated in the future. In addition to a significant reduction in costs and lead times, this also results in substantial advantages in terms of process stability, scrap reduction, and sustainability.
“Our goal is to bring the paintability of polyolefins to where it belongs: into the injection molding process itself,” says Dr. Susanne Wintzheimer, project manager at SKZ, describing the motivation behind the project. “If we succeed in adjusting the necessary surface functionality during the molding process itself, this will create enormous industrial leverage—especially for small and medium-sized enterprises.”
Relevance for Industry and Sustainability
The economic and environmental significance of the project is considerable. Significant cost-saving potential is expected due to the elimination of external surface pretreatment steps and the ability to continue using cost-effective polyolefins instead of more expensive alternative materials.
At the same time, the use of emission-intensive processes and critical chemicals is reduced—a clear contribution to current regulatory requirements and sustainability goals.
Furthermore, the developed approach opens up possibilities beyond traditional painting, for example for bonding, printing, or multi-component processes in which surface adhesion plays a central role.
Participation Expressly Encouraged
The “KombiHaft” project is scheduled to run for two years and, in the spirit of collaborative industrial research, thrives on close interaction with industry. Companies along the entire value chain—from material manufacturers and processors to coaters and equipment manufacturers—are expressly invited to participate in the project steering committee.
Participation offers the opportunity to contribute your own requirements, gain early access to results, and actively help shape the development of a potentially disruptive technology. Participation in the committee is free of charge and non-binding.
Funding
The “KombiHaft” research project (funding code 01IF25112N) is funded by the Federal Ministry for Economic Affairs and Energy (BMWE) as part of the Industrial Collaborative Research (IGF) program. The project is managed by the German Aerospace Center (DLR).
“KombiHaft” Research Project Launches: New Approaches to Creating Paint-Friendly Polyolefin Surfaces in Injection Molding
Polyolefins such as polypropylene and polyethylene are indispensable in industrial production due to their excellent mechanical properties, low cost, and comparatively good carbon footprint.
At the same time, their nonpolar surfaces pose a significant hurdle for subsequent painting and coating processes. In practice, this has so far led to cost-intensive pretreatment methods that are the subject of environmental debate, or even to material substitutions that entail both economic and sustainability-related drawbacks.
This is precisely where the “KombiHaft” project comes in—with the clear goal of significantly improving the paintability of polyolefins directly within the injection molding process and thereby fundamentally streamlining existing process chains.
Material Innovations Meet Process Intelligence
The project’s innovative approach is based on the targeted combination of two solution spaces that have previously been considered separately: material-based functionalization and mold-based process control.
At Fraunhofer IFAM, novel photoreactive adhesion promoters are being developed that selectively accumulate on the component surface during the injection molding process. Through subsequent UV activation, these are stably fixed in the form of molecularly thin layers, thereby enabling improved paintability of polyolefin surfaces—without additional wet chemical or thermal pretreatment steps.
In doing so, known critical classes of substances are deliberately avoided; instead, the focus is on thermally stable, cost-effective, and toxicologically safe molecular designs.
In parallel, the SKZ is developing mold design strategies that specifically influence the boundary layer structure of the component. The focus is on innovative concepts for active and passive surface temperature control—for example, through ceramic heating systems or functional mold coatings—as well as biomimetic-inspired microstructuring of the mold surface.
These measures directly affect the molding and cooling behavior and thus the molecular and morphological characteristics of the component surface—key control variables for the resulting adhesion in subsequent painting and coating processes.
“With ‘KombiHaft,’ we are taking a holistic approach for the first time, in which material chemistry and process control are not considered in isolation but are specifically linked,” explains Dr. Martin Wiesing, project manager at Fraunhofer IFAM. “It is precisely this systematic coupling that opens up the possibility of adjusting adhesion properties in a reproducible and industrially robust manner.”
Inline Activation as the Key to a Process Revolution
A key objective of the project is to integrate the activation of the plastic surface directly into the ongoing injection molding process. The adhesion promoters are introduced as additives, migrate in a controlled manner to the component surface, and are activated by UV radiation immediately after molding.
This inline approach promises a paradigm shift: time-consuming process steps that must be adapted to the surface of the supplied component—such as flame treatment, plasma activation, or primer application—could be completely eliminated in the future. In addition to a significant reduction in costs and lead times, this also results in substantial advantages in terms of process stability, scrap reduction, and sustainability.
“Our goal is to bring the paintability of polyolefins to where it belongs: into the injection molding process itself,” says Dr. Susanne Wintzheimer, project manager at SKZ, describing the motivation behind the project. “If we succeed in adjusting the necessary surface functionality during the molding process itself, this will create enormous industrial leverage—especially for small and medium-sized enterprises.”
Relevance for Industry and Sustainability
The economic and environmental significance of the project is considerable. Significant cost-saving potential is expected due to the elimination of external surface pretreatment steps and the ability to continue using cost-effective polyolefins instead of more expensive alternative materials.
At the same time, the use of emission-intensive processes and critical chemicals is reduced—a clear contribution to current regulatory requirements and sustainability goals.
Furthermore, the developed approach opens up possibilities beyond traditional painting, for example for bonding, printing, or multi-component processes in which surface adhesion plays a central role.
Participation Expressly Encouraged
The “KombiHaft” project is scheduled to run for two years and, in the spirit of collaborative industrial research, thrives on close interaction with industry. Companies along the entire value chain—from material manufacturers and processors to coaters and equipment manufacturers—are expressly invited to participate in the project steering committee.
Participation offers the opportunity to contribute your own requirements, gain early access to results, and actively help shape the development of a potentially disruptive technology. Participation in the committee is free of charge and non-binding.
Funding
The “KombiHaft” research project (funding code 01IF25112N) is funded by the Federal Ministry for Economic Affairs and Energy (BMWE) as part of the Industrial Collaborative Research (IGF) program. The project is managed by the German Aerospace Center (DLR).
