Hydroxymethylated resorcinol (HMR) primer to improve the performance of wood-adhesive bonds – A review

Böger, Thomas; Sánchez-Ferrer, Antoni; Richter, Klaus

doi:10.1016/j.ijadhadh.2021.103070

Cited by 7 publications

(2 citation statements)

References 33 publications

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“…In previous studies, primer polymer films have been used in wood-related applications [11][12][13]. For example, a study on flame-retardant wood revealed that only the synergistic effect between the primer and the plasma layer could lead to flame retardancy, and the primer helped to smooth the surface of the plasma coating, seal the pores of the wood, and promote the formation of a more uniform plasma layer [11].…”

Section: Introductionmentioning

confidence: 99%

Effect of TiO2@CaCO3 Waterborne Primer on the Coloring Performance of Inkjet-Printed Wood Product Coatings

Sang,

Yang

2023

Coatings

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Calcium carbonate (CaCO3) is a widely used inorganic filling pigment used in coatings, and it is known for its nontoxicity, odorlessness, and environmental friendliness. The application of CaCO3 as a filler can effectively reduce raw material costs, and optimization of the filler formula enhances the coating film performance. In this study, oak planks were prepared as substrates for water-based inkjet printing. Three composite water-based primers with different TiO2-to-CaCO3 ratios and a polyurethane resin primer were used to prepare the substrate for the printing surface. The properties of the water-based primer coating and the water-based inkjet printing coating were characterized and analyzed via Fourier-transform infrared spectroscopy, video-based contact angle analysis, and environmental scanning electron microscopy. The aim was to investigate the effects of the composite waterborne primer coatings on the ink absorption and coloring properties of the interface between wood substrates and waterborne inkjet coatings. Sample WDCC-3#, with a TiO2-to-CaCO3 ratio of 15:35, exhibited the most comprehensive characteristics. The wood surface coated with 15 g/m2 of the polyurethane resin primer and 15 g/m2 of WDCC-3# exhibited a 5.8° contact angle of the water-based ink, first-grade adhesion, 4 H hardness, 70.52 whiteness value, and a roughness of ~2.33. The surface of the printed water-based inkjet-coated substrate was uniform and smooth, featuring rounded and transparent edges of the water-based ink droplets and a small CMYK color difference value. Therefore, the composite waterborne primer, incorporating TiO2 and CaCO3 in specific ratios, can be effectively combined with waterborne polyurethane primer coatings. This combination significantly improves the interfacial compatibility between the oak surface and waterborne inkjet coatings, leading to enhanced ink absorption on the oak plank surface during printing. This results in a high degree of color reproduction and clearer printed images. Overall, this study provides valuable insights for the development of primer programs for the industrial application of waterborne digital inkjet technology on wood products.

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Section: Introductionmentioning

confidence: 99%

Effect of TiO2@CaCO3 Waterborne Primer on the Coloring Performance of Inkjet-Printed Wood Product Coatings

Sang,

Yang

2023

Coatings

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“…Traditionally, surface activation is accomplished using appropriate chemical primers and liquid bonding agents, respectively, which are nowadays increasingly solvent-free or water based. Among the wide range of chemical primer systems both single and two component solutions have been patented (Böger et al 2022), such as the poly(ethylene imine) (PEI)-based single-component primer patented by Weyerhaeuser Company (Tacoma WA, USA) or the two-component primer by Rhône Poulenc S.A. (Paris, France) relying on isocyanate/alkoxysilane chemistry. Further patented primers are based on hydroxymethylated resorcinol (HMR, US Department of Agriculture), or polyoxyethylene (20) sorbitan monolaurate (Polysorbate 20, Henkel AG & Co. KGaA, Düsseldorf, Germany), the latter featuring bonding capabilities to polyurethane adhesives.…”

Section: Introductionmentioning

confidence: 99%

Triboelectric surface field strength of wood after brushing

Leiter

Myna

Frybort³

et al. 2022

Wood Sci Technol

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Mechanical friction causes electrical surface charges on wooden surfaces. In this research, triboelectric activation of solid wood surfaces was investigated by using a wood brushing machine. The extent of activation and the potential influence of machine parameters, or the influence of various wood species are questions so far unanswered. The electrical surface field strengths were continuously detected by means of an electric field meter. Machine settings, such as feed rate and brush pressure, have been varied to better understand the effects on the resulting surface charges. Data showed that nylon and tynex brushes lead to strong positive electric surface field strengths while natural fibers lead to less positive surface field strengths. In contrast, steel wire brushes showed negative electrical field strengths for oak wood, slightly positive field strengths for beech wood and stronger positive field strengths for softwoods. Overall, the tendency that a higher brush pressure led to higher recorded electrical surface field strengths while a faster feed rate reduced the field strengths was observed. As these findings were influenced by wood species and brushing materials, a better understanding of specific triboelectric interactions is essential for future applications. Tailoring surface charges can be an asset for new technical applications, such as chemistry-free primer treatments prior to wood coating.

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Wood-water interactions of primers to enhance wood-polyurethane bonding performance

Böger,

Engelhardt,

Suh

et al. 2023

Wood Sci Technol

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Today, using one-component polyurethane (1c-PUR) adhesives in the manufacturing of engineered wood products from spruce is common practice. However, the use of other wood species can require the application of a primer to fulfill normative requirements. Previous research shows the primers’ effectiveness, especially in moist environments. However, the primers’ exact mode of action remains not yet fully understood. We hypothesize a reduction in the hygroscopic behavior of the primer-treated wood—intensity and kinetics—that could reduce the formation of stresses in the bond line region. To test this hypothesis, two commercially available primers, based on Polysorbate 20 and poly(ethylene glycol), and the hydroxymethylated resorcinol (HMR) primer are examined with wood from beech, birch, larch, and Douglas fir. Swelling experiments show that of each primer a portion infiltrates and swells the wood cell walls, affecting the wood’s hygroscopic and mechanical properties. In stepwise sorption experiments, it is seen that the primers influence differently the amount of moisture uptaken by the wood (adsorption). The rate at which the moisture spreads within the wood (diffusivity) also changed differently for the primers, while the rate at which the moisture moves through the wood (permeability) remains unchanged. The application of all primers improves the bulk flow behavior and thus the void penetration of the adhesive into the lumina in the interphase region, which in turn leads to a reduced bond line thickness. All three primers improve the tensile shear strength. The hygroscopic changes caused by the primers appear too small to be claimed as the sole and primary cause of their functionality, whereas more relevance is seen in the primers’ cell wall infiltration and the increased adhesive’s void penetration.

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Hydroxymethylated resorcinol (HMR) primer to improve the performance of wood-adhesive bonds – A review

Cited by 7 publications

References 33 publications

Effect of TiO2@CaCO3 Waterborne Primer on the Coloring Performance of Inkjet-Printed Wood Product Coatings

Effect of TiO2@CaCO3 Waterborne Primer on the Coloring Performance of Inkjet-Printed Wood Product Coatings

Triboelectric surface field strength of wood after brushing

Wood-water interactions of primers to enhance wood-polyurethane bonding performance

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