Pulping processes and insulation production
In collaboration with our project partner Loick Biowertstoff GmbH, we are investigating which processes can be used to break down and further process beech wood into fibrous materials for the production of insulation mats and wood foam or wood-foam granules. Amongst other things, low-value damaged wood (calamity wood) is to be used for this purpose.
Fiber mats
In order to achieve the desired structure, strength and elasticity in the fiber mats, we want to adapt a commonly used manufacturing process for wood-fiber insulation materials, into which supporting fibers made from thermoplastic material are introduced. Bicomponent fibers (in short: “bico fibers”) are generally used for this purpose; these consist of a permanently elastic inner part and a hot-melt adhesive sheath. Our goals:
- Minimization of the proportion of bico fibers, and testing of bio-based bico fibers
- Optimization of the blending of the two very different fiber types (wood fibers and plastic fibers)
- Optimization of the heating of the fibrous fleece / bonding between wood fibers and bico fibers, for example through:
- hot air
- hot vapor
- microwave or high-frequency excitation
- Production of a flexible insulation mat made from beech fibers and bico fibers, which could be used analogously to the softwood insulation mats available up until now - for example for between-rafter insulation in roofs, compartment insulation in wooden construction and drywall construction, or the filling of hollow bricks.
Wood foam / wood-foam granules
For the production of wood foams, we employ a process developed at the Fraunhofer WKI. In order to produce wood-foam granules, the manufactured wood foams are subsequently broken down into granules using various crushing units and, if necessary, additionally hydrophobized. The goal is a pourable (solid or liquid) material that can be utilized in the insulation of buildings.
Flame protection
In order to achieve the building material class “normally flammable”, we will, if necessary, enhance the various beech-wood fiber insulation materials by means of flame retardants, which will be incorporated during the manufacturing process. The aim is for “highly fire-retardant” (60 min) or “fire-resistant” (90 min) walls to be constructed using the thermal-insulation bricks.
Procedure for the filling of hollow bricks
As a specific application example for the new beech insulation materials, we are testing the filling of hollow bricks (“thermal-insulation bricks”) in this project - in cooperation with the industrial partners Loick Biowertstoff and Ziegelwerk Bellenberg.
Bricks with large / regular hollow chambers (“hole-pattern-dependent”)
- Insertion of the beech insulation material into the hollow chambers with the aid of filling machines currently used by the brick manufacturer Bellenberg for filling using mineral wool or glass wool
- Technical adaptation of the plant, for example with regard to feeders, strengths and cutting tools
Bricks with small / irregular hollow chambers (“hole-pattern-independent”):
- Filling of the hollow chambers with liquid or pourable insulation materials.
For both types of bricks, the adhesion between the brick surfaces and the insulation material is to be investigated and optimized. Objective: The insulation material should be “bonded” in the holes in such a way that no insulation material can escape when the bricks are cut or drilled.
Pilot plant for insulation production
In collaboration with the company Loick, we are developing and constructing a functional pilot plant for the production of insulation material made from beech wood.
In the development of an economically viable plant concept, we consider, amongst other things:
- Selection of an optimal pulping process (dry or wet pulping)
- Selection of a suitable pulping unit (refiner, ecopulser) for beech-wood fibers as the main component of the plant
- Selection and design of plant components such as mixing units for wood and bico fibers, fiber-fleece laydown, and the drying system
- Testing of possible methods for the filling of hole-pattern-independent bricks with wood-foam granules
- Raw material and logistics costs, suitable logistics and storage concept
Recycling process / recyclability
In collaboration with the company Bellenberg, we are investigating the recyclability of the insulation-filled bricks. This includes:
- Process development for the separation of bricks and insulation material
- Tests on the reconditioning of the emptied bricks and their renewed utilization as thermal-insulation bricks
- Tests on the reprocessing of wood-fiber insulation materials to create new insulation materials
- Investigations into the utilization of broken bricks (e.g. as granulate for plants)
Evaluation of insulation material and component properties
During the course of the project, we will evaluate the beech-based insulation materials (mats, boards, foams and granulates) with regard to their physical-technological properties and their utilization in bricks and wall structures.
- Insulation materials: determination and optimization of mechanical properties such as thickness, density and dynamic stiffness in accordance with current standards
- Determination of the thermal conductivity of the brick with and without insulation filling
- Water absorption and release of the filled brick (if necessary with hydrophobic insulation material)
- Determination of the fire-resistance duration
- Testing of all developed beech-wood insulation materials for normal flammability before and after enhancement by means of flame retardants
- Determination and analysis of the gases produced in the event of fire
- Production and testing of a wall made from various perforated bricks with various insulation fillings (project partner: Bellenberg)
Life-cycle assessment
Parallel to the development of the insulation materials, Loick will determine the material and energy requirements for the production of the insulation materials. These will serve as the basis for assessing greenhouse-gas emissions - from the “cradle to the factory gate” (cradle-to-gate). In addition, possible climate impacts in the “end-of-life” phase (disposal of the insulation materials) or “second life” phase (renewed utilization of the insulation materials) will be considered. By means of contribution analyses, the greenhouse-gas-intensive process steps will be identified and optimization potentials derived.
Fraunhofer Institute for Wood Research 
