PARTICLEBOARDS PRODUCED WITH EPOXY INK WASTE AND BTH POLYMER AS ADHESIVES

2 Escola de Engenharia de São Carlos, Universidade de São Paulo (EESC/USP)/ São Carlos SP, Brasil. 3 Universidade Federal de Rondônia (UNIR)/ Porto Velho RO, Brasil. 4 Escola de Engenharia de São Carlos, Universidade de São Paulo (EESC/USP)/ São Carlos SP, Brasil. Received in: 2-8-2018 Accepted in: 7-5-2018 Engenharia Agrícola, Jaboticabal, v.38, n.5, p.797-804, sep./oct. 2018 Doi: http://dx.doi.org/10.1590/1809-4430-Eng.Agric.v38n5p797-804/2018


INTRODUCTION
Wood is a versatile material that can be used in several situations (Lahr et al., 2016;Christoforo et al., 2017;Almeida et al., 2017).In order to have it as a raw material, several mechanical processes are necessary, from its extraction in the forest to the final product, and the generation of waste is inevitable (Fiorelli et al., 2014;Fiorelli et al., 2017).
It is estimated that in the processing of wood logs in sawmills, only 40% to 60% is transformed into final product, being generated around 50% of waste, from sawdust to other larger pieces without added value (Vieira et al., 2010;Ofoegbu et al., 2014;Silva et al., 2017;Monteiro et al., 2017).
For the production of particleboards, the conversion between raw material and final product is greater, because in addition the use of all log, it can be used wood wastes from other processes (Souza et al., 2014;Alves et al., 2014;Christoforo et al., 2015).
For consolidation of the particleboard in the production process, besides the wood is also necessary adhesives, right temperature and pressure (Feng et al., 2012;Silva et al., 2013a;Atar et al., 2014;Ruziak et al., 2017;Nascimento et al., 2017).Urea-formaldehyde is one of the main adhesives used to make panels, but in the hot pressing process, the emission of toxic gases that can be harmful to workers' health (Liu & Zhu, 2014;Belini et al., 2015;Liang et al., 2016a;Liang et al., 2016b).
For this reason, research with the use of alternative adhesives, such as castor-based polyurethane resin, among others, is being carried out with a view to reducing the use of urea-formaldehyde (Silva et al., 2013b;Mao et al., 2014;Ferro et al., 2014;Zeng et al., 2016;Zhang et al. 2017).
Engenharia Agrícola, Jaboticabal, v.38, n.5, p.797-804, sep./oct. 2018 Epoxy resins are used for the manufacture of automotive inks used in the process of finishing metal parts by the electrostatic painting technique.In this process, the powdered ink is charged electrostatically and thrown onto the surface of the object, the residue of which is the portion of ink did not adhere to the part.
Polyhydroxybutyrate polymer (BTH) is produced naturally by bacteria from renewable energy sources.The production process begins in the cultivation of bacteria of the species Alcaligenes eutrophus in bioreactors, in which these are fed with sugar cane, mainly sucrose.In their metabolism, microorganisms ingest the sugars and turn them into intracellular granules that are actually polyesters (Quental et al., 2010;Casarin et al., 2013).
The aim of this research is to verify the feasibility of the production of particleboards using wood wastes and two alternative substitute adhesives for urea-formaldehyde, which are the epoxy ink waste and polyhydroxybutyrate polymer (BTH), according to mechanical properties.

MATERIAL AND METHODS
In this research it was used Pinus sp.particles to the production of the boards, obtained by the processing of wood wastes in hammer mill Willye type (Marconi, Model MA 680).Particles were produced from wood wastes from a sawmill in the region of São Carlos, state of São Paulo, Brazil.
Urea-formaldehyde resin (pH = 7.8; solids content = 65%; density = 1.27 g/cm³) was used as adhesive.In order to replace the urea-formaldehyde, the epoxy ink waste and the polyhydroxybutyrate polymer (BTH), both in the solid state and in the form of very fine powders, were used in the proportions shown in Tables 1 and 2, respectively.
About the parameters presented in Table 1 (to particleboards with epoxy ink waste), the pressure used (4 MPa) was according to Nascimento et al. (2017), Macedo et al. (2015) and Bertolini et al., (2014).For pressing time, the minimum necessary to complete the melting of the epoxy ink waste at the adopted temperatures was used.
The curing agents of the epoxy ink react in the temperature range of 140°C to 200°C.For this reason, the temperature of the press was adopted at 180°C and 190°C, considering the thermal degradation of wood particles and the capacity of the press machine used.
About the epoxy ink waste content, a minimum percentage was established that could provide to the particleboards the minimum requirements values of mechanical properties according to ABNT NBR 14810:3 (2013) and ANSI A208:1 (2009) Standards Codes.Thus, the proportions of 10% and 20% were used arbitrarily, replacing the urea-formaldehyde resin, because authors didn't find in the literature any information about the use of this waste as adhesive on particleboards manufacturing.The parameters adopted for particleboards with BTH polymer as an adhesive manufacturing, except for the pressing temperature, were the same as those used in the production of particleboards with epoxy ink waste.Temperatures for pressing the BTH polymer particleboard were set below 175°C, which is the melt temperature of the polymer (Machado et al., 2010).Therefore, the adopted pressing temperatures were 140°C and 160°C (Table 2).Thus, the proportions of 10% and 20% were used arbitrarily, replacing the urea-formaldehyde resin, because authors didn't find in the literature any information about use of BTH polymer as adhesive on particleboards manufacturing.For each combination described in Tables 1 and 2, 3 particleboards (dimensions: 25 cm × 25 cm × 1 cm) were produced, totaling 108 particleboards for each type of used adhesive.
Particleboard mechanical properties determining carried out according to ABNT NBR 14810:3 (2013) Standard Code, and the mechanical tests are illustrated in the Figure 1.Table 3 presents the number of specimens (N o ) to mechanical property determining from each particleboard by treatment.The results obtained for the properties are compared with the requirements of ABNT NBR 14810:3 (2013) and ANSI A208:1 (2009).Engenharia Agrícola,Jaboticabal,v.38,n.5,Tas & Sevinçli (2015) studied particleboards manufactured with Pinus brutia and different ureaformaldehyde contents (6%, 10% and 12%).Epoxy ink waste particleboards PT average values determined in this research were higher to particleboards with Pinus brutia and all urea-formaldehyde contents.MOR average values found to epoxy ink waste and BTH polymer particleboards were close to particleboard with 6% of urea-formaldehyde content.

CONCLUSIONS
From the discussion of the results presented previously, it is concluded that: -Researches about new raw materials to the production of wood panels instead of the traditional ones are important; therefore, they become an interesting way of using wastes in the manufacturing process; -Particleboards combinations with epoxy ink waste reached the minimum requirements recommended by the Standard Code ABNT NBR 14810:3 (2013) for perpendicular tensile of the particleboard strength.Combinations produced at the pressing temperature of 190°C, reached the requirements of ANSI A208:1 (2009) for perpendicular tensile; -All proposed combinations to manufacture BTH polymer particleboards didn't show satisfactory mechanical properties in comparison to the Standard Codes; -Average values to mechanical properties presented by epoxy ink waste and BTH polymer particleboard were close in comparison with other researches with Pinus sp. and urea-formaldehyde adhesive contents; -Other combinations of wood specie, time, pressure and temperature, epoxy ink waste and BTH polymer contents can be studied for the manufacture of particleboards that meet regulatory requirements in relationship with their mechanical properties.

TABLE 3 .FIGURE 1 .FIGURE 2 .FIGURE 3 .FIGURE 4 .
FIGURE 1. Mechanical tests: (a) static bending; (b) Pullout strength of screw on face; (c) Pullout strength of screw on top.RESULTS AND DISCUSSIONEpoxy ink waste particleboardsFigures 2 to 6 presents average values and the range of the coefficient of variation (CV) for each epoxy ink waste particleboards manufacturing treatments amongst the minimum value required by ABNT NBR 14810:3 (2013) and ANSI A208:1 (2009) Standards Codes.Average values of the perpendicular tensile of the particleboard on the face ranged from 0.45 MPa to 1.46

Figures 7 FIGURE 7 .FIGURE 8 .
Figures 7 to 11 presents average values and the range of the coefficient of variation (CV) for each BTH polymer particleboards manufacturing combination and, for each mechanical property the minimum value required by ABNT NBR 14810:3 (2013) and ANSI A208:1 (2009) Standards Codes.

DiscussionsMOR,
RAPf and RAPt average values to ink waste particleboard were close to Pinus sp particleboard manufactured with urea formaldehyde by Torrell et al. (2013), but, for the BTH polymer particleboard, just MOR and RAPt average values were close.Iwakiri et al. (2010) researched Pinus taeda particleboards with urea-formaldehyde and found to MOR, MOE and PT average values equal to 0.58 MPa, 12.03 MPa and 1866 MPa.MOR average values determined to epoxy ink waste and BTH polymer particleboards were close to the Iwakiri et al. (2010).MOR average values determined to epoxy ink waste and BTH polymer particleboards were higher to the value determine by Fiorelli et al. (2014) for Pinus sp.particleboard manufactured with urea-formaldehyde (MOR = 8.69 MPa), but lower when compared to PT (0.54 MPa) and MOE (1,813 MPa) values.

TABLE 1 .
Particleboard manufacturing parameters combinations with epoxy ink waste.

TABLE 2 .
Particleboard manufacturing parameters combinations with BTH polymer.