The effects of water-based insulation paint applied to laminate flooring panels on the thermal conductivity coefficient and adhesion resistance

Abstract

In an effort to reduce negative feedback resulting from temperature fluctuations, house floors are commonly laid with laminate flooring. The aim of this study was to study the thermal insulation properties and adhesion strength of the water-based insulation paint mixed with hollow glass spheres and applied onto the laminate flooring. The objective was to determine whether a prepared insulation paint mixture can be used instead of backing paper. For this purpose, two different laminate flooring samples were used. In the first case, the upper surface of the sample was coated with decorative paper and the lining surface was coated with backing paper. The upper surface of the second sample was coated with decorative paper and the lining surface was not coated with backing paper. Then, insulation paint mixture was applied 2, 4, or 6 times to the lining surfaces of both groups, and experimental results were obtained. As the number of layers was increased, the insulation mixture applied to the lining surfaces of the test samples was found to contribute positively to thermal insulation and adhesion resistance of specimens.

Full Article

The Effects of Water-based Insulation Paint Applied to Laminate Flooring Panels on the Thermal Conductivity Coefficient and Adhesion Resistance

Ali Kabakci,^a and Haci İsmail Kesik ^b,*

In an effort to reduce negative feedback resulting from temperature fluctuations, house floors are commonly laid with laminate flooring. The aim of this study was to study the thermal insulation properties and adhesion strength of the water-based insulation paint mixed with hollow glass spheres and applied onto the laminate flooring. The objective was to determine whether a prepared insulation paint mixture can be used instead of backing paper. For this purpose, two different laminate flooring samples were used. In the first case, the upper surface of the sample was coated with decorative paper and the lining surface was coated with backing paper. The upper surface of the second sample was coated with decorative paper and the lining surface was not coated with backing paper. Then, insulation paint mixture was applied 2, 4, or 6 times to the lining surfaces of both groups, and experimental results were obtained. As the number of layers was increased, the insulation mixture applied to the lining surfaces of the test samples was found to contribute positively to thermal insulation and adhesion resistance of specimens.

Keywords: Format; Laminate flooring; Water-based insulation paint; Hollow glass microspheres; Thermal conductivity coefficient; Adhesion resistance

Contact information: a: Department of Furniture and Interior Design, Incirli Technical High School, Ankara, 06010, Turkey; b: Department of Forest Industrial Engineering, Faculty of Forestry, Kastamonu University, Kastamonu, 37150, Turkey; *Corresponding author: hismailkesik@kastamonu.edu.tr

INTRODUCTION

People express their lifestyles by covering the ceilings, walls, and floors in places where they live, and the consumers expect the heat insulation to be sufficient. Notably, the cold conductivity from the ground has made the floor coverings indispensable with regard to thermal insulation. In many countries of the world, as in Turkey, coatings and finishes are produced from different materials (Döngel et al. 2008; Kaymakcı et al. 2014). The high cost of solid wood, dimensional change at different ratios in three directions (radial, tangent, and longitudinal), and some other disadvantages of wood, such as the difficulty of providing different colors and patterns, has provided motivation to consider composite wood flooring (laminate flooring) (As 1998). The use of composite floors has brought along some advantages such as not requiring varnish and paint on the upper surface, good abrasion resistance, easy installation, and thermal insulation. However, the contribution of this application to thermal insulation is not at the desired level yet. In order to improve the thermal insulation properties of laminate floorings, which are lower cost than in solid wood materials (Sahin Kol et al. 2010; Uysal et al. 2011), low density and interstitial materials are reinforced into the middle layer and lining layers of laminate flooring.

There are many studies on the thermal insulation properties of composite materials, wood panels, and protective layers supported by different nano materials. Composite materials treated with different coatings (paper, PVC, etc.) and preservatives (paint, varnish, etc.) have thermal conductivity values that vary depending on the concentration of chemicals used in them (Acik and Tutus 2012; Ustaomer and Usta 2017; Sahin and Dongel 2018). Another material developed for isolation is water-based isolation paint, which contains additives such as micro-sized hollow glass spheres. Currently, these kinds of applications are used for interior and exterior facades of buildings for thermal, acoustic, and moisture isolation (Wang et al. 2014; Posmyk 2016; Kimetsan 2018). The use of water-based paints that are reinforced by micro-sized hollow glass spheres in floor coverings and the investigation of their heat insulation properties can contribute to the flooring industry.

It is important to know the thermal conductivity coefficient in the evaluation of the performance of thermal insulation materials (Zhou et al. 2013), and a low conductivity coefficient is one of the desirable features (Nemli and Kalaycioglu 2002; Lan et al. 2014). Further enhancement of the porous structure positively influenced the thermal performance of water-based paints reinforced by micro-sized hollow glass spheres (Dzyazko and Konstantinovsky 2014; Wang et al. 2014). The thermal conductivity values of the paints based on thicknesses of 0.10 to 0.18 W/mK have been reported (Chukhlanov et al. 2017). The thermal conductivity coefficient values of WBNTP-D45 at the dry film thickness are 0.017 to 0.022 W/mK (Tech. Rep.1 2010) and demonstrate that 72 °C on one surface of the test device is measured at 36 °C on the other surface (Oztin 2014). In some studies, the thermal conductivity values of hollow water-based paints are quite different from each other and it has been reported that academic circles cannot reach a consensus on the quality of thermal insulation (Bozsaky 2017, 2018).

If the material to be used for heat insulation purposes is in paint, then the adhesion of the paint with material is the most important criteria. The adhesion resistance values of protective layers may vary depending on weather conditions, the properties of the resin used, and its molecular dimensions. The number of layers in the applications, the varnish, and the modification of the paints are also important. In addition, it has been reported that the adhesion resistance of the protective layers may vary depending on their material density and surface hardness (Budakci and Sonmez 2010; Dilik et al. 2015). Especially in recent years, by means of the production of protective layers with nano technological products, new developments have been encountered. There is a higher surface area and a higher increase in molecule ratios per head in these developments (Dongguang et al. 2002). This may contribute positively to the adhesion resistance of nano-technological protective layers. As a matter of fact, it has been reported that the adhesion resistance may decrease with mixing some additives (Panchenko et al. 2018). Various protective layers with different adhesion resistance values have been applied to different wood material surfaces: on cellulosic based (1.86 to 3.62 MPa), on synthetic based (3.72 to 5.43 MPa), on water-based (1.44 to 3.73 MPa), on polyurethane based (2.37 to 4.05 MPa), and on acrylic based (3.66 to 3.80 MPa). Adhesion resistance values differ in the literature (Ozcifci and Ozpak 2008; Atar and Peker 2010; Dilik et al. 2015; Ozdemir et al. 2015; Sogutlu et al. 2016; Kesik et al. 2017; Oncel et al. 2019).

The aim of this study was to determine the effects of applying water-based insulation paint to laminate floorings with different numbers of layers (2, 4, and 6) in order to determine their thermal conductivity and adhesion resistance. In addition, this research aimed to determine whether insulation paint mixture can be used instead of backing paper.

EXPERIMENTAL

Materials

High-density fiberboard (HDF)

In this study, laminate flooring based on HDF, which is widely used in flooring, was preferred as a test material because of its direct primability and coating and polishing ability. Two different laminate floorings used in the experiments were manufactured by SFC Plant, Kastamonu, Turkey. According to the relevant standards, the laminate flooring was coated with backing paper on one of the plates to be laminated, and the other surface was specially produced with 350 N/cm² press pressure in dimensions of 2070 × 2610 mm without covering the surface with backing paper. The backing paper used was 150 g/m², and overlay paper was 140 g/m². After pressing, the average density value was determined to be 0.96 g/cm³ in coated laminate flooring with backing paper, and 0.95 g/cm³ in the uncoated laminate floorings (TS EN 323 1999). The pre-press backing paper (a) and the laminate without backing paper (b) within the parquet elements are shown in Fig. 1. In Fig. 2, it is possible to observe the elements of laminate flooring with (a), without (b) the backing paper and a test sample, and (c) following paint application.

Fig. 1. Before pressing the laminate flooring elements with (a) and without (b) backing paper

Fig. 2. After pressing the laminate flooring with (a), without (b) backing paper, and painted test sample (c)

Water-based covering agents

Water-based filler varnish (WBF-D45), water-based topcoat varnish (WBV-D45), and water-based heat-insulating paint mixed with hollow glass spheres (WBTP-D45) are the materials that were used in the experiments. The sourcing company (Kimetsan Co., Ltd., Ankara, Turkey) had defined the paint as water-based nano and micro technological insulating paint (WBNTP-D45) with the property to make micro-acrylic modified polyurethane insulation that was heat and water proof. The paint was prepared by mixing acrylic modified polyurethane nano-size resin (70%) with micro-size hollow glass spheres (30%). The technical specifications of the paints, varnishes and applications used in the study are given in Table 1 (Technical Bulletin. 2018).

Table 1. Technical Specifications Used Agents and their Applications Parameters

The SEM image of the large and small microscale hollow glass spheres in the paint is shown in Fig. 3, and the SEM (Quanta FEG 250; FEI Company, Brno, Czech Republic) at) image of the WBTP-D45 applied to the test sample is given in Fig. 4. All SEM images were captured at Kastamonu University Central Research Laboratory with the test specimens.

Fig. 3. SEM image of hollow glass spheres

Preparation of experiments

Test specimens prepared in the dimensions of 310 × 310 mm had been kept in an air conditioning cabinet at a temperature of 20 ± 2 °C with a relative humidity of 65 ± 5% until they reached a constant weight (TS 2471 2005). The test specimens to be used in surface adhesion were prepared as 100 × 100 × 8 mm tests and 80 were prepared at 300 × 300 × 8 mm for thermal conductivity tests. According to the company recommendations, WBTP-D45 laminate was first applied as a layer, and WBF-D45 was used for filling to provide good bonding with parquet lining surfaces. For the second application, WBTP-D45 was applied 2, 4, and 6 times separately for both coated and uncoated groups of samples. For the final application, WBV-D45 was applied as a coat to the upper surface of each sample to prevent surface abrasion and contamination. The samples were coated with paints and varnishes according to company specifications and ASTM-D 3023-98 (2011) values.

Fig. 4. SEM image of the WBTP-D45 applied to the test sample

The WBTP-D45 application was made in layers with 15 min between each layer application. The hollow glass spheres were added to the paint surface and mixed well before each application. Oven dried WBTP-D45 film thicknesses were measured as nearly 60 µm. Paint applications were made with a spray gun (Fig. 5) with a Fuji brand bag type compressor (Fuji Q4 Gold Tribune; Fuji Industrial Spray Equipment Ltd., Toronto, ON, Canada) and high volume low pressure (HVLP).

Thermal conductivity tests were conducted according to TS EN 12627 (2003) in the testing laboratory of the Department of Woodworking Industrial Engineering of Gazi University Faculty of Technology with a Linseis HFM 300 tester (Linseis Messgerate GmbH, Selb, Germany). The top plate temperature of the device calibrated to 30 °C and the bottom was set to 20 °C, and the painted surfaces of the test specimens were placed between the plates and thermal conductivity coefficient values were determined by means of computer software.