Project Report for public use

Size: px

Start display at page:

Download "Project Report for public use"

Everett Stanley
5 years ago
Views:

1 LIFE Project WPC-Recycle Project number LIFE00 ENV/D/ Project Report for public use Edited November 2004 Project data Duration Beneficiary Werzalit AG & Co. KG Contact person Herr Dr. Matthias Schulte Address Gronauer Str. 70, D Oberstenfeld Telephone Fax Website

2 WPC Recycle - Layman Report 1. Introduction In Europe 2000/2001 about 48 Mio. m³ of wood based panels have been produced. The predominant part of these products are produced using thermosetting glues. Thermosetting glues are cured under high pressure and high temperature. Products made with thermosetting glues (i.e. particle boards) are not post formable by using high temperatures. Since a few years in Europe starts the investigation of an innovative technology using thermoplastics as binder for wood based panels. These mixtures of wood particles and thermoplastics, called Wood Plastic Composites (WPC), offer some advantages compared to the conventional wood based panels cured with thermosetting glues, like the flow behaviour when heated and the postforming properties. Using thermoplastics for wood based material first the thermoplastics are melted, then mixed with wood particles (compounding) and then cured by cooling in a press die in the closed press. The project Material utilization of plastic waste in the production of products based on new, polymer-bound wood materials (WPC Recycle), funded by the financial instrument LIFE by the European Community, has been carried out by the company Werzalit AG+Co. KG. The project time was 30 month. The company Werzalit AG+Co. KG is a traditional, international operating, medium sized company, producing wood based products since over 80 years. A special know how of the company is the production of moulded and decorative covered wood particle products for exterior use. Since decades these products are produced with thermosetting resins based on a technology invented and patented by Werzalit. Since a few years Werzalit also made basic investigations regarding WPC. The aim of the project WPC Recycle was to build a pilot plant for the production of decorative covered Wood Plastic Composites. With this pilot plant it should be investigated, if by producing WPC, the thermoplastic component could be exchanged up to 100 % by recycled thermoplastics and the influence of this change on the material properties. It was the aim to create, without using wood preservatives, weather resistant and fungi resistant wood based materials with decorative surfaces for exterior use. 2. Application of juvenile thermoplastics After building, delivery, assembling and implementing of the pilot plant the first step of the project was to produce material with the desired and optimised properties. By changing the components (wood, juvenile thermoplastic) and optimising the process parameters different WPC-materials could be produced. These materials then were tested regarding there specific properties and the resulting fields of application. Typical properties tested are the bending strength based on DIN EN ISO 178 and the impact bending based on DIN EN ISO 179. The used thermoplastic component was polypropylene (PP). Layman Report WPC-Recycle

3 It could be shown, that the properties of wood plastic composites are highly correlated to the coupling agent used, which is used to get a better adhesion between the unpolar thermoplastics and the polar wood particles. The coupling agents are typically so called MAPP (Maleineacidanhydride-PP). These coupling agents may vary chemically in a wide range. Choosing the right one it is possible to enhance the bending properties by increasing the wood content (Figure 1). The impact bending decreases with increasing wood content. In this case, too, a high correlation to the coupling agent has been obtained. A higher influence on the impact bending, on the same level of wood content, has the thermoplastic component (Figure 3). In total it can be demonstrated, that choosing the right recipe of the mixture has an enormous influence on the properties of the finished WPC-material. Bending strength [N/mm²] 55 Bending strength (average lengthwise/crosswise) in correlation with wood content and recipe (MAPP-Type) 52, , , ,1 35 PP1 + 3% MAPP1 PP1+ 5% MAPP2 + 3 % MAPP ,5 PP1 + 10% MAPP2 + 2% MAPP1 54,7 39,7 Figure 1: Wood content [%] 20,0 20,0 Impact bending in correlation with wood content and recipe Figure 2: Charpy Impact bending [kj/m²] 19,0 18,0 17,0 16,0 15,0 14,0 13,0 12,0 11,0 10,0 17,9 15,4 PP1 +MAPP1 PP1 + 3% MAPP1 + 5% MAPP2 PP1 + 2% MAPP1 + 10% MAPP Wood content [%] 13,4 15,6 10,5 Layman Report WPC-Recycle

4 Correlation between MAPP-Type and -Concentration on impact bending Figure 3. Charpy Schlagzähigkeit kj/m²] 13,0 12,0 11,0 10,0 9,0 8,0 7,0 6,0 5,0 4,0 3,0 6,0 4,6 3,8 PP2 + MAPP5 PP2 + MAPP1 PP2 + MAPP3 PP1 + MAPP1 10,5 6,7 5,8 2 2,2 2,4 2,6 2,8 3 3,2 3,4 3,6 3,8 4 MAPP-Content [%] 12,5 6,4 5,9 85,0 Bending strength (lengthwise) in Correlation to MAPP-Type -Concentration Bending strength (lengthwise) [N/mm²] 80,0 75,0 70,0 65,0 80,4 70,1 79,8 75,1 64,5 PP2 + MAPP1 77,7 74,2 68,3 66,0 60,0 60,5 61,4 PP2 + MAPP4 + 1,5 % Schwarz (PP) 55,0 2 3 MAPP-Concentration [%] PP2 + MAPP3 PP1 + MAPP1 4 Figure 4 MAPP: Contact agent PP: Thermoplastic (Polypropylene) 3. Application of recycling-thermoplastics After optimising the technological properties of the wood plastic composite with juvenile thermoplastic, in a second step the thermoplastic component was exchanged up to 100 % with recycling PP. The used material was industrial waste clearly defined and with a certificate about the MFI (Melt Flow Index). Exchanging the juvenile Polypropylene with recycled polypropylene does not significantly influence the material properties. The influence of all other parameter like wood content or surface covering has a higher influence on the material properties than the recycled thermoplastic component. Layman Report WPC-Recycle

particles, the contamination with metal components, the size of the particles/granulates (influences the behaviour in the conveyor systems), the colour (monochrome or multicoloured) and the spectrum

5 The offers of recycled plastics on the market vary dramatically. While describing the quality of recycling plastics, it is important to know the mixture (pure PP, or a mixture with other types of thermoplastics like polyethylene), the contamination with mineral particles, the contamination with metal components, the size of the particles/granulates (influences the behaviour in the conveyor systems), the colour (monochrome or multicoloured) and the spectrum of technical properties. Like mentioned before, the melt flow index (MFI) and it s variation is a very important criteria describing the material. Figure 5: Recycling-pellets in Big Bag 4. Coating A further aim of the project was the production of two side decorative covered semi finished products (panels). The adhesion between the thermoplastic foils and the WPC core material should be obtained without using additional glues. To reach this goal the currently extruded molten WPC (hot, still flowing woodthermoplastic-mixture) and the thermoplastic foils were combined in a Figure 6: Samples covered with foil on two sides. double belt press, calibrated and cooled. For the handling of the foils a special frame was integrated. With this equipment it was possible to apply the foils on the upper side or the lower side only or on both sides of the panel. The defined goal was thereby reached. Choosing the right thickness of the foil, the right MFI and the right production temperatures a perfect, non destructible adhesion between thermoplastic foil and the WPC-core material can be achieved. It is insignificant if juvenile or recycled thermoplastics are used for the core material. Layman Report WPC-Recycle

5. Weather resistance In order to test the weather resistance, four different types of material surfaces have been installed in a weathering tester equipment.

The results of the tests show, that the adhesion of the thermoplastic foils to the core material is without any failure, even after 12 weeks of testing.

6 5. Weather resistance In order to test the weather resistance, four different types of material surfaces have been installed in a weathering tester equipment. In this equipment the surfaces of the material are tested with UV-radiation and alternating with water spraying. The results of the tests show, that the adhesion of the thermoplastic foils to the core material is without any failure, even after 12 weeks of testing. The gloss of the used foils reduces slightly, but nevertheless the weather resistance is on a high level. The uncovered samples with colour pigments reduces the gloss dramatically, the colour changed (becomes light) and the surface became very chalky. Instead, the uncovered samples with colour pigments and UV-protecting additives changed there colour only slightly and chalking could nearly not be detected. Hence it is possible to create a weather resistant surface on wood plastic composite materials by using thermoplastic foils or by using suitable UV-protecting additives hours 1000 hours Figure 7: Test samples after weather resistance test; without (left) and with UVadditives 6. Fungi resistance To evaluate the suitability for exterior use of wood based materials the weather resistance test is an important one. Additionally the test against wood destroying fungi is needed. For this evaluation, WPC-material with different wood content was proved with standardised tests. Relating to ENV the resistance against 3 species of white and brown rot was tested and relating to ENV 807 the resistance against soft rot was tested. It can be summarised, that all tested material types are resistant against basidiomycetes (white rot, brown rot). There are no significant differences between material with juvenile thermoplastic and recycled thermoplastic. The mass loss tested with soft rot is less than for the very resistant tropical wood species Azobé. The tested WPC-material can be classified in the best resistance class (1). All results correlate closely with the wood content. Increasing wood content leads to increasing mass loss. Concluding these results it can be summarised: With wood plastic composites fungi and weather resistant products for exterior use can be produced, without using wood Layman Report WPC-Recycle

Prototype development As the last step of the project a prototype was designed.

7 preservatives. To reach this the wood content is not allowed to be too high. The interpretation of the results implies that the limit for exterior use without wood preservatives is a wood content of 65 %. There is no negative influence by using recycled plastics. 7. Prototype development As the last step of the project a prototype was designed. The goal of this design was to test process relevant parameters in the compression moulding process with a component containing the typical complexity of a product in serial production. For this purpose a kind of table top was designed, with different curvatures on the edge, a smooth surface and deep cuts on the backside with functional elements like screw holes. For the production of this prototype a press die was designed and built, that could be implemented in an existing multi daylight press. Figure 8: Prototype test sample (backside) and relating press die for compression moulding In the compression moulding process molten WPC-material was positioned in the middle of the press die. Closing the press the molten WPC-material flows into the cavities of the press die. The press die for the production of the prototype was designed in a way, that thermoplastic foils can be inserted as well. In the last phase of the project in this way prototypes covered with foils could be produced. The conclusion of the prototype tests is: Using the right temperature in the press die compression moulding with WPC-material is possible. There is no difference between material with juvenile thermoplastic or recycled thermoplastic. Very thin walls can be realised (about 2 mm). Steps in thickness (from very thin to very thick) are possible without problems. Because WPC-material has a very high Layman Report WPC-Recycle

8 specific density (1,1 g/cm³) thin walls in a product are not only possible, they are even necessary to reduce the weight. The cooling time in the closed press die is short. The cooling time is about 1/3 of the press time of a comparable product made out of moulded particle board. Covering the prototype with thermoplastic foils using the compression moulding process is possible. The adhesion within this process between foil and core material is good. But until now the bending behaviour of the products after leaving the press is not solved completely. 8. Evaluation NEW RANGE OF APPLICATION: With products based on wood plastic composite material it is possible to conquer market segments delivered until now only by the plastic industry. CO 2 -REDUCTION: This submits the displacement of pure plastic products through ecological wood based materials. The amount of wood based material with renewable, CO 2 -neutral wood from sustainable forests increase. RECYCLING-MATERIAL: The possible exchanging of the juvenile thermoplastic component by recycled thermoplastics enhances the ecological value of the material. Thermoplastics, produced of fossil raw materials can be used for material recycling (not only for thermal recycling). This treats with care the natural energy resources. LONG LIFE CYCLE: Long living products for exterior use based on wood can be realised with WPC, without using wood preservatives. ENVIRONMENTALLY COMPATIBLE: Leaching of preservative salts and heavy metals into nature can be avoided. PROTECTION OF TROPICAL FORESTS: Tropical timber is not needed, instead wood from sustainable forests in neighbourhood to the production facilities can be used. INNOVATION: The production of WPC-products is an innovative technology, in Europe until now picked-up only by a few producers. While operating the project and publication Werzalit succeed in pushing the technology and widen the European interest of people. The interest in the WPC-technology is increasing rapidly in Europe. This can be detected for example looking at the amount of visitors on the last Symposium Global Wood and Natural Fibre Composites Symposium in Kassel. In former times there were about 80 participants, last time there were about 300. But it has to be regarded, that most of the participants are from research institutes, from equipment producer or from producer of additives for the plastic industry. WPC-producing companies have been an absolute minority. WIDE APPLICATION AS A CHALLENGE: Werzalit could demonstrate and present the successful possibilities of the production with WPC. Customers are very concerned, but there is a lot of scepticism as well, because WPC is a new class of material, not yet described enough. The definition and classification of WPC will be one of the major tasks of the future. Among others this will be a task for the standard committee of the European Commission. Layman Report WPC-Recycle

Unit 156: Polymer Manufacturing Processes

Unit 156: Polymer Manufacturing Processes Unit code J/615/3315 Unit level 4 Credit value 15 Aim This unit is designed to develop students knowledge and understanding of the main manufacturing processes