FORMULATION OF PRIMERS TO WOOD FLOORINGS COVERING USING PVB FILMS FROM THE RECYCLING OF WINDSHIELDS

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1 FORMULATION OF PRIMERS TO WOOD FLOORINGS COVERING USING PVB FILMS FROM THE RECYCLING OF WINDSHIELDS Isabella M. Vargas 1,2*, Helio Wiebeck 1 1* Escola Politécnica da Universidade de São Paulo, Av. Prof. Lineu Prestes, 580, São Paulo SP, cep: , Brazil - isabella.marini@poli.usp.br; hwiebeck@usp.br; 2 Renner Sayerlack S.A. isabella@sayerlack.com.br The present work features an alternative for the utilization of the windshield after its use. The recycling of the laminated glass, through a series of grindings, make possible to obtain a PVB - poly(vinyl butyral) - sheet impregnated with a small amount of filler, that now has as final disposal the sanitary landfill. In this study the film of PVB was used in the formulation of a primer, due to its high flexibility and good adherence to the wood, and the results obtained show that the primer prepared with the PVB sheet, in alcoholic solution, mixed with a trifuncional acrylic monomer, like TMPTA (trimethylolpropane triacrylate), obtain good results of adherence, scrape adhesion, flexibility and stability when applied on wood flooring and could substitute the primers used nowadays that are UV curings products, however water based ones, and that has a high cost because of the imported resins that are used in their formulations. It was observed that larger the amount of solution of PVB better the flexibility of the film and, consequently, better its scrape adhesion. Introduction The laminated glasses are constituted by the sandwich glass/pvb/glass. The PVB - poly(vinyl butyral) - is a polymer with great UV solar light stability, excellent adherence to glass and others substrates, besides its excellent flexibility. 1, 2 The laminated glasses find aplication not only in the automobilistc industry, like windshields, but in the building area too, as a security factor in doors and windows made of glass and without frames. 3 Nowadays, the final disposal of these laminated glasses is the sanitary landfill and, only in Brazil, approximately 120 thousand of windshields per month are discarded. If which one weights 15 kg being 14 kg of glass and 1 kg of PVB, approximately 1,8 thousand tonnes of product ends in the landfills and only the PVB takes 500 years to be assimilated by the nature. 4 Through a series of grindings is possible to separate the PVB sheet (or film), impregnated with a small amount of filler, from the glass and in this work this PVB film was used to formulate primers to wood flooring covering. The wood floorings are the favorites thanks to their aesthetic, comfort and hygiene. However this wood must be protect of stains and time degradation and for this, it is necessary to apply a protective layer. Among the several types of coverings, the most used industrially are the ultraviolet radiation cured ones, that presents high chemical and abrasion resistance 5, and the PVB will be incorporate in this type of covering. The PVB film was added to a primer, thas has as main property to promote the adherence between the wood and all the covering system that will be applied on it. 6 Besides that, this primer has to

2 have a good flexibility to improve the scrap adhesion results. 7 Because of these two demands the PVB was choosen. The PVB was added in different quantities and the properties of the different formulations were studied. Experimental PVB based formulation Two formulations based on PVB were made but before this, the PVB were dissolved in ethyl alcohol, as Table 1 and this solution were called PVB solution. Table 1 PVB solution Raw materials Quantity (%) PVB film 9 Ethyl Alcohol 91 The concept of dual-cure was adopted to formulate the primers, where the PVB solution will use the termic drying (to evaporate the ethyl alcohol) and to have the UV (ultraviolet) cure was added in the formulation a trifunctional monomer, the TMPTA (trimethylolpropane triacrylate). The formulations are showed in the Table 2. Table 2 Primers formulation Darocur Primer PVB solution TMPTA a 1173 b Primer 1 80% 15% 0,9% Primer 2 88,55% 7,50% 0,45% a TMPTA (trimethylolpropane triacrylate) was provided by Cytec; b photoinitiator provided by Ciba Specialty Chemicals Inc. Tests of hardness, adherence and scrap adhesion were made with these formulations. Hardness tests In this work two kinds of hardness tests were made: Sward Rocker Hardness, based in the ASTM D and Persoz Hardness based in the ASTM D

3 The primers were applied on glass plates, with a thickness of 100 µm and submitted a 60 C for 5 minutes and than cured in a mercury lamp with an energy dosage in UVA of 544 mj/cm² and an irradiance of 254 mw/cm². Adherence and scrap adhesion tests This test was based in the ASTM D and to evaluate the primers adherence, they were applied on jatobá (a wood specie used in the wood flooring industry) in the process showed in the Figure 1. To have a standard, in one of the pieces a water based UV primer (produced by Renner Sayeralck) was applied. Topcoat Primer Sealer : 3 layers Substrate: jatobá Figure 1 Process applied to the adherence tests All the products were applied by roller machine. The sealer and the topcoat are produced by Renner Sayerlack and each layer applied form each one were, respectively, 20g/m². The layer of primer applied was from 15 g/m². The primer and sealer layers were gelled with mercury lamp with a dosage of 161mJ/cm² and an irradiance of 250mW/cm² and the topcoat was cured with a mercury lamp too, with a dosage of 544 mj/cm² and an irradiance of 254 mw/cm². The scrap adhesion test was based in the ASTM D and the analysis were done in pieces made as Figure 1. Results and Discussion Hardness tests The hardness results obtained for each primer is showed in Table 3.

4 Table 3 Results of Sward Rocker and Persoz Hardness for each primer Primer Sward-Rocker Hardness Persoz Hardness (SHR) From the results of Table 3 it is possible to observed that the primer 2 is more flexible (less harder) than primer 1. It was already expected once that the primer 2 contains more PVB solution and the PVB is a flexible polymer (besides that, this PVB used in the laminated glass contains 30% of plasticizers). The decrease of TMPTA quantity also helps to increase the flexibility because as a trifunctional monomer it will cure as a tridimesional net (which increases the hardness). The increase of flexibility is important in the primer formulation because it is well know that this primer should follow the wood elongation, caused by the humidity and changes of temperature. 8 Adherence and Scrap adhesion tests The results obtained in adherence and scrap adhesion tests are showed in Table 4. Table 4 Results of adherence and scrap adhesion tests Primer Adherence Scrap adhesion Standard 100% 3,5 kg 1 100% 2,5 kg 2 100% 3,5 kg From the results obtained in Table 4 it was noted that both of primers presented excellent adherence to the wood. In the scrap adhesion tests, was observed that the primer 2 got better results than primer 1, and the same result of the standard primer. The best result of primer 2 can be explained by its higher flexibility (when compared to primer 1) obtained by the higher amount of PVB solution, that also improve the adherence in the wood thanks 9, 10 to its hidroxyl groups content.

5 Conclusion The results obtained show that the primer prepared with the PVB sheet in alcoholic solution, mixed with a trifuncional acrylic monomer, like TMPTA, when applied on wood flooring, obtain good results of adherence, scrape adhesion, and flexibility and could substitute the primers used nowadays that are UV curings products, however water based ones, and that has a high cost because of the imported resins that are used in their formulations. It was observed that larger the amount of solution of PVB, better the flexibility of the film and, consequently, better its scrape adhesion. Acknowledgements To Renner Sayerlack S.A., especially to Maria Cristina K.C.Carvalho. References 1. F. W. Billmeyer, Textbook of polymer science, Wiley-Interscience, New York, P. Nylen; E. Sunderland, Modern surface coatings: a textbook of the chemistry and technology of paints, varnishes and lacquers, Interscience, London, T. S. Valera, PhD Thesis, Escola Politécnica da Universidade de São Paulo, R. Holzheim, Setor reciclagem, 2004, available in 5. J. P. Bleus et al., European Coatings Journal, 2005, jan./feb., K. Biesbrouck, Hard or flexilble coatings: infuence on measured performances, Radtech 2005: proceedings, Hannover, P. Kelly; B. Williams; S. Pendlebury, Stick!...UV adhesion characteristics on difficult wood, Radtech 2003: proceedings, Hannover, Z. W. Wicks; F. N. Jones; S. P. Pappas, Organic coatings: science and technology, John Wiley & Sons, New York, 1994; Vol M. L. Hallensleben, Ullmann s Encyclopedia of Industrial Chemistry, Ed. VCH, Weinheim, 1992; Vol.A21, D. H. Parker, Enciclopedia de la quimica industrial, Ed. Urmo, Bilbao, 1970; Vol. 7.