Effect of pressing conditions on some surface properties of HDF laminate parquets

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1 Indian Journal of Engineering & Materials Sciences Vol. 23, August 2016, pp Effect of pressing conditions on some surface properties of HDF laminate parquets Mehmet Erdal Kara a, Zekeriya Yerlikaya b, Saim Ateş c * & Çağrı Olgun c a SFC Integrated Forestry Products, Kastamonu, Turkey b Department of Primary Education, Faculty of Education, Kastamonu University, Kastamonu, Turkey c Department of Forest Industrial Engineering, Faculty of Forestry, Kastamonu University, Kastamonu, Turkey Received 30 March 2015; accepted 26 April 2016 In this study, the effects of lamination conditions on some commercial high density fiberboard (HDF) panels surface quality characteristics, surface strength, impact resistance test (large diameter ball test), curing degree, scratch resistance, abrasion resistance are investigated. For this purpose, HDF panels are produced from mixture wood fibers (50% black pine and 50% beech wood) as 8.3 mm thickness. After panels sanded to 7.3 mm thickness, laminated at different pressures and times. It has been found that high pressure and short-term press time conditions have significant effect on surface strength, impact resistance, and abrasion resistance values. The best surface quality measurements are obtained from A1 group, pressure 340 kg/m² and 13 s pressing time (average of surface strength value of this group is 1.83 N/mm 2, impact resistance value is N and abrasion resistance value is 3650 revolution), but the lowest value is B3 groups, 320 kg/m² pressure and pressing time of 18 s (average of surface strength of this group is 1.58 N/mm 2, impact resistance value is 20 N and abrasion resistance value is 3200 revolutions). Besides production factors of HDF panels and laminating material properties, press operating conditions have been found to be decisive factors in laminate parquet pressing process for high surface quality. Key Words: HDF laminate parquet, Laminating, Press conditions, Surface quality Fiberboard is the most widely used building material for the furniture industries and interior design applications 1. Generally, fiberboards are classified by their density, that low density is the lower than 0.35 g/cm 3, medium density is between 0.35 to 0.8 g/cm 3 and high density is upper than 0.8 g/cm 3. Production types of fiberboards are usually changed the combination of plant fiber (generally hardwood, softwood or agricultural residues) and resins (most widely based on urea formaldehyde (UF), phenol formaldehyde (PF) and melamine formaldehyde (MF) respectively). Plant fibers are defibrated by using thermomechanical pulping (TMP) methods in fiberboard industry. In this method, lignin, the chemical compound which bond between the plant fibers, is softened by water vapour before mechanically defibration, not removing actually 2. Thus, fiberboards colors are brownish and surface treatments applied to fiberboards for visually in interior design and furniture industries. Nowadays, different types of surface treatment applied to the fiberboards are available like surface coating with lamination. Utilization of laminates at surface coating has become popular by their advantages such as cheaper, durable and pattern diversity 3. Although the other types of fiberboards, HDF are used generally as the carrier panel layer for laminate parquet, consisting of different layers (Fig. 1). Upper sheet paper are saturated with melamine resin in hot process and can be formed of previously pressed one or more thin layers (HPL = high pressure laminate or CPL= continuous pressure laminate). In addition, laminate parquets are produced by direct pressure laminate (DPL) methods, in which pattern paper and cover film layer direct glued on carrier panel to obtain the highest quality. The cover film layer protects pattern layer from wear and lower surface of the carrier panel is covered with a protective balancing layer 4. In addition, it was reported that surface coating with lamination improved the panels properties, such as aging durability, abrasion resistance, scratch resistance, formaldehyde emission, mechanical properties, *Corresponding author ( saimates@kastamonu.edu.tr) Fig. 1 Layers of laminate parquet 1

2 KARA et al.: SURFACE PROPERTIES OF HDF LAMINATE PARQUETS 275 dimensional stabilities, decay resistance, etc These values are important laminate parquet qualities and quality control standards generally need some requirement 13. Laminate parquets exposure generally the abrasive forces like frictional force on end used areas. For this reason, surface quality test and values more important than the other properties These qualities are affected from carrier layer material properties, laminating material properties, and lamination system parameters (press duration, temperature and pressure) 14. Nemli et al. 6 investigated that effect of chances press parameters and thickness on quality properties of continuous pressed laminates (CPL). They reported that chances on press temperature and press cycle influenced the abrasion and scratch properties of panels. Nemli and Çolakoğlu 7 reported that surface coating type and technique are affected technological properties of particleboard, increased mechanical properties and thermal conductivity, and decreased thickness swelling and formaldehyde emission value. It was investigated that the most suitable surface coating material types were selected for interior applications of particle boards according to some physical and mechanical properties. According to test results, Continuous press laminate thickness, surface coating material, wood veneer thickness were not significantly affected the mechanical properties of particle board. But coating material and wood veneer type affected the physical properties of particleboards 8. Nemli 10 studied the influences of some process factors (overlay and varnish material, resin mixture, structure of CPL), on stratch, abrasion and cigarette resistance. It was reported that overlay and varnish materials and used resin mixture for foil production significiantly affected the tested properties 10. İstek et al. 11 investigated the effect of décor paper and resin type on physical, mechanical and surface quality properties of particleboard. They reported that lamination with MF resin impregnated décor paper showed better performance than UF and UF+MF resin impregnated papers. In addition, resin type and décor paper type affected the physical, mechanical and surface properties of particleboards. Jarusombuti et al. 15 were studied surface characteristics and overlaying properties of thermally treated ruberwood MDFs. They treated ruberwood fibers at different temperatures and time. After the MDF production with treated fibers, MDF samples were overlayed with veneer sheets they are tested bonding strength with MDF samples and veneer sheet. According to these results, bonding strength between MDF and veneer sheet were negatively affected with thermal treatment. Kara et al. 16 investigated before the effects of lamination system parameters on the MDF surface, having 0.60 and 0.65 g/cm 3, laminated with high gloss decor paper on different press temperatures (175 C and 185 C) and durations (30, 40, 60 and 75 s). They determined changes on scratch resistance, curing degree, brightness and surface strength properties. It was reported that surface strength properties negatively affected with increasing duration time, although, these properties increasing with increasing carrier panel density. Moreover, it was shown that shorter press temperature and longer press durations have positive effect on surface brightness values. In this study, it was aimed to determine the changes on some surface properties of HDF panel coating process with various press pressures and durations. Material and Methods HDF panels production HDF panels (8.3 mm thickness), produced from Anatolian black pine (Pinus nigra) and beech (Fagus orientalis) wood mixture (50:50 blend) in commercially panel production line of SFC Integrated Forestry Products Company (Turkey). After the panels were conditioned at 20 C and 65% relative humidity, they sanded by using grits sequences as a 7.3 ±0.1 mm thickness. HDF panels coating After sanding the HDF panels surfaces, firstly the lower surface of panels were covered with a moisture-resistant paper, raw weight is 60 g/m² and impregnated by melamine formaldehyde resin. Upper surface of panels covered with urea and melamine formaldehyde resins (50%-50%) impregnated paper, raw weight is 60 g/m² and printed different decorative wood pattern (28 g/m²),. This lamination process was performed on a six piston Siempelkamp press (Siempelkamp, Germany) at three different pressures ( kg/m²) and three different durations ( s). Determination of the surface properties Test measurements were made on 10 different test samples according to TS EN and TSE standards. Panels surface strength tests were performed with Imal IB 600 test machine (Imal Pal Group, Italy) according to EN and impact

3 276 INDIAN J. ENG. MATER. SCI., AUGUST 2016 resistance tests (large diameter ball) were performed according to EN Abrasion resistance tests were performed according to EN Scratch resistance tests were performed according to ISO , and curing degree test were performed according to Ghaemy et al. 22. Density profiles of nonlaminated and laminated panels analysed with İMAL DPX200 test machine (Imal Pal Group, Italy) Test results were evaluated with analysis of multivariate one way variance (MANOVA) (P < 0.001) and Duncan test (P < 0.05) by using SPSS 19 program for determining effects of independent parameters. Results and Discussion Table 1 shows the results of laminated panels surface qualities tests. Average values of surface strength, impact resistance, abrasion resistance, scratch resistance, curing degree ranged from 1.58 N/mm² to 1.83 N/mm², 20 N to 25 N, 3150 to 3650 rpm, 4.5 N to 5 N and 3 to 4, respectively. Statistical results of MANOVA for determination the effects of press pressure, duration time and interactions on properties are shown Table 2 (P < 0.001). Press pressure was not any significantly effect on curing degree, scratch resistance, press duration was not significantly effect on whole measurements values (P < 0.001). However, press pressure and interactions between press pressure and time have significantly effect on surface strength, impact resistance, and abrasion resistance. The values of A1-A2-A3, B1-B2-B3 and C1-C2-C3 test samples are observed that there are significant differences with α = 0.05 error probability with respect to the DUNCAN test for surface strength, impact resistance, abrasion resistance values (Table 3). HDF parquet surfaces strength values in the different pressing conditions the average values are shown in Fig. 2. As can be seen from Fig. 2, the surface strength values changed depending on press pressure. It was found that, generally surface strength values decreasing with decreasing press pressure. Moreover, Table 1 Average values of surface strength, impact resistance, abrasion resistance, scratch resistance, curing degree HDF Press Press Surface Impact Abrasion Scratch Curing PARQUET duration pressure strength resistance resistance resistance degree Type s kg/m² N/mm² N Revolution N A ,5 3,0 A ,5 4,0 A ,5 4,0 B ,5 3,0 B ,5 3,0 B ,5 4,0 C ,0 C ,5 3,0 C ,5 4,0 Table 2 MANOVA results for independent variables Sources Independent variables Sum of squares D.F. Mean squares Fsum P value Press pressure Press duration Interactions Error Total * Not significantly effect on parameters Surface strength P<0.001 Impact resistance P<0.001 Abrasion resistance P<0.001 Surface strength * Impact resistance * Abrasion resistance * Surface strength P<0.001 Impact resistance P<0.001 Abrasion resistance P<0.001 Surface strength Impact resistance Abrasion resistance Surface strength Impact resistance Abrasion resistance

4 KARA et al.: SURFACE PROPERTIES OF HDF LAMINATE PARQUETS 277 it has also been found to be a direct correlation between press durations and pressure values. Surface strength values changed positively with increasing durations while decreasing press pressure. It was determined that highest surface strength was of 1.83 N/mm² for 340 kg/m² pressure and 13 s press duration (A1), and lowest was of 1.58 N/mm² for 320 kg/ m² pressure and 15 s press duration (B3). Nemli 10 reported that HPL (high pressure laminate) showed highest resistance values against for stretch Table 3 Duncan test results (P < 0.05) Group Duncan Groups* Surface strength Impact resistance Abrasion resistance A 1 F C E A 2 C B ABC A 3 A AB CD B 1 E B CD B 2 E C E B 3 A A AB C 1 DE B D C 2 CD B BCD C 3 B B A * Different letters represent statistical significance while same latters indicate a similarity of differences (P < 0.05) and abrasion than the other coating types. It was seemed that HPL coatings has overlay film layer, which consist of more amount of melamine resin than decorative pattern paper layer, and this layer resin was more efficiently on curing with high pressure and temperatures. Same reason can be shown for the decreasing of surface strength value with decreasing press pressure in this study. The average values of surface impact strength of laminated HDFs in different pressing conditions are shown in Fig. 3. It was determined that, impact resistance values of A1 (340 kg/m²:13 s) group higher than the other groups according to average impact resistance values as shown in Fig. 3. Impact resistance values were significantly changed with decreasing press pressure while increasing press durations (P< 0.001). It was determined that highest impact resistance was of 25 N for 340 kg/m² pressure and 13 s press duration (A1), and lowest was of 20 N for 320 kg/m² pressure and 15 s press duration (B3). For this situation, it can be said that surface density was increased by pressed pattern paper and cover film layers with high pressure. According to Fig. 4, upper and Fig. 2 Average surface strength results of the HDF samples Fig. 3 Average impact resistance results of the HDF samples Fig. 4 Density profile of the non-laminated and laminated HDF samples

5 278 INDIAN J. ENG. MATER. SCI., AUGUST 2016 material properties and panel production conditions are important for manufacturing of laminate parquet in fiberboard industry. For this reason, correct choice of panel production conditions, coating paper qualities and lamination process conditions are vitaly important for high quality laminate parquet manufacturing. Since, this study was carried out in an industrial production unit, it can easily be adapted to another process. Fig. 5 Average abrasion resistance results of the HDF samples lower surface density profile improved with coating and fiberboard surface nearly 1 to 6 mm, improved with additional pressing stage in coating process. So that HDF panel properties are improved with increasing density 2. The average values of HDFs surface abrasion resistance of the laminate produced in different pressing conditions are shown in Fig. 5. It was determined that, abrasion resistance values of high pressure (340 kg/m²) groups are higher than lower pressure groups according to average impact resistance values in Fig. 5. Moreover, it has also been found to be a direct correlation between press durations and pressure values. Abrasion resistance values changed positively with increasing press durations while decreasing press pressure. It was determined that highest abrasion resistance was of 3650 revolution for 340 kg/m² pressure and 13 s press duration (A1), and lowest was of 3150 revolution for 320 kg/m² pressure and 18 s press duration (C3). The reason for this may be explained that interfacial strong physical and/or chemical bonds between HDF panel and coating material have been increased with high press pressure 6,11,15. Besides, the similar reason of impact resistance can be shown for changing of abrasion resistance values. Conclusions In this study, effects of coating process conditions on some surface qualities of HDF laminated parquet have been determined. It was concluded that variations in the pressing conditions affect the surface quality and some mechanical properties. Laminate parquet press conditions as well as the production conditions of HDF boards are effective. Coating References 1 Li K Y, Fleischmann C M & Spearpoint M J, Chem Eng Sci, 95 (2013), pg Eroğlu H & Usta M, Liflevha Üretim Teknolojisi, (KTÜ Orman Fakültesi Yayınları, Trabzon), Özdemir F & Tutuş A, KSU J Eng Sci, Special Issue (2012) Chow P, Janowiak J J & Price E W, Wood Fiber Sci, 18(1) (1996) Nemli G, Gezer E D & Hızıroğlu S, Build Environ, 38 (2003) Nemli G & Çolakoğlu G, Build Environ, 40 (2005) Nemli G, Örs Y & Kalaycıoğlu H, Constr Build Mater, 19 (2005) Nemli G, Yıldız S & Gezer E D, Dech Monog, 56(3) (2005) Nemli G, J Mater Process Technol, 195(1) (2008) Istek A, Aydemir D & Aksu S, Bioresources, 5(2) (2010) Büyüksarı Ü, Bioresources, 7(1) (2012) ISO , International Organization for Standardization, Geneva, Switzerland, Kılıç M, Burdurlu E, Aslan S, Altun S & Tümerdem Ö, Mater Des, 30(10) (2009) Jarusombuti S, Ayrilmis N, Bauchongkol P & Fueangvivat V, Bioresources, 5 (2) (2010) Kara M E, İstek A, Esgin E, The effect of lamination conditions on surface characteristics of particleboard, paper presented at 3 rd Int Nonwood Forest Products Symp, Kahramanmaraş, Turkey, TS EN 325, Turkish Standards Institution, Ankara, Turkey, TS EN 326-1, Turkish Standards Institution, Ankara, Turkey, EN 13329, European Committee for Standardization, Brussels, Belgium, EN 438, European Committee for Standardization, Brussels, Belgium, ISO , International Organization for Standardization, Geneve, Switzerland, Ghaemy M, Sarrafi Y, & Karim M, Iran Polym J, 19(9) (2010)