High-pressure Laminates Research Articles

Effect of Kraft Lignin from Hardwood on Viscoelastic, Thermal, Mechanical and Aging Performance of High Pressure Laminates

In this work, the synthesis and characterization of phenol-formaldehyde resols modified with 10, 20 and 30 wt% of Kraft lignin (a waste from pulp industry) from hardwood were studied. In all cases, the Kraft lignin was activated by hydroxymethylation. The resols characterization involved industrial measurements of free formaldehyde, viscosity, total solids and density. The resins were used for the industrial impregnation of Kraft-type paper and the production of laboratory laminates. The mechanical and thermal properties of the laminates were determined. Mechanical measurements included tensile, flexural, impact and interlaminar tests. Thermogravimetric and dynamic mechanical analysis were used for the thermal characterization. In addition, the aging of materials in water was studied. No significant differences in mechanical and thermal properties between traditional and modified materials were found with replacement up to 20 wt% of phenol. Modified laminates exhibited better water resistance due to the lignin hydrophobicity. This work was carried out in collaboration with Centro S.A., San Francisco, Cordoba, Argentina, a high pressure-laminates industry.

Fluorinated polyhedral oligomeric silsesquioxane nanoparticles to boost the dirt repellence of high pressure laminates

High pressure laminates (HPLs) are attractive, resistant to environmental effects and good cost-benefit decorative surface composite materials whose properties can be tailored to meet specific market demands. In this study, the substantial improvement of dirt repellence of HPLs with simultaneous enhancement of its abrasion resistance was achieved for the first time by incorporating nonafluorohexyl polyhedral oligomeric silsesquioxane (FH-POSS) nanoparticles (up to 1% w/w) into a melamine–formaldehyde (MF) resin matrix used to impregnate decorative and overlay papers required for HPLs production. FH-POSS particles were synthesized and thoroughly characterized by 13C and 29Si solid state nuclear magnetic resonance (NMR) spectroscopy, and by X-ray diffraction (XRD) analysis. Fluoroalkyl moieties in FH-POSS afforded increased hydrophobicity to HPLs thus providing improved surface cleanability, whereas abrasion resistance was improved due to the robust silica core of the POSS particles. Hydrophobicity of HPLs doped with FH-POSS increased with time, after resin curing, and this was attributed to migration of FH-POSS nanoparticles to the composite surface.

Wood products and green chemistry

Abstract Key message Green chemistry for and from wood has developed numerous industrial products, namely biosourced, green wood adhesives and preservatives, foams, composite matrices, laminates, hard and flexible plastics, flexible films, and abrasive grinding discs, and their number is still growing. Introduction This review addresses (1) the elimination of toxic aldehydes from the most common wood panel adhesive, the one based on urea, itself a natural product, (2) biosourced adhesives derived from wood or other vegetable matter and used for wood products, and (3) wood and bark tannin-based foams, natural fiber composites using tannin matrices, paper surface laminates and continuous high-pressure paper laminates using tannin-furanics, hard plastics based on tannin-furanic materials and some of their applications, flexible biosourced tannin-furanic films, and biosourced wood preservatives.

High Pressure Laminates with Antimicrobial Properties.

High-pressure laminates (HPLs) are durable, resistant to environmental effects and good cost-benefit decorative surface composite materials with special properties tailored to meet market demand. In the present work, polyhexamethylene biguanide (PHMB) was incorporated for the first time into melamine-formaldehyde resin (MF) matrix on the outer layer of HPLs to provide them antimicrobial properties. Chemical binding of PHMB to resin matrix was detected on the surface of produced HPLs by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Antimicrobial evaluation tests were carried out on the ensuing HPLs doped with PHMB against gram-positive Listeria innocua and gram-negative Escherichia coli bacteria. The results revealed that laminates prepared with 1.0 wt % PHMB in MF resin were bacteriostatic (i.e., inhibited the growth of microorganisms), whereas those prepared with 2.4 wt % PHMB in MF resin exhibited bactericidal activity (i.e., inactivated the inoculated microorganisms). The results herein reported disclose a promising strategy for the production of HPLs with antimicrobial activity without affecting basic intrinsic quality parameters of composite material.

Determination of Tensile Properties of Selected Building Sealants in Combination with High-pressure Compact Laminate (HPL)

One of the current issues in the Czech building industry is an efficient implementation of seal joint between constructions. An undesirable penetration of water, moisture or air between structural elements may have a negative effect on their reliability and may also affect the length of expected service life. This issue is addressed in detail in the following paper. The experimental part of the research is aimed at ascertaining the technical properties of sealants and on verification of their potential usage in practise. Furthermore, this article focuses on the preparation and subsequent production of test specimens, and also on the experimental verification of their tensile properties at a temperature of (20 ± 3) °C and (-22 ± 2) °C. For the tests, composite high pressure laminates (i.e. HPL Trespa Meteon) are chosen for the cladding. In order to find the best solution ten types of commonly manufactured industrial sealants is selected. At the same time the emphasis was on representation of sealants in various price categories. The main conclusion of tests is the fact that it is not possible to responsibly choose a suitable material without taking appropriate measurements or having previous experience. A secondary conclusion to this article is the fact that there are significant differences between individual sealants in the results they provide in combination with selected cladding material. Moreover, the method also suggests that the use of the most expensive sealant does not always provide the best results.

Adhesive bond strength development evaluation using ABES in different lignocellulosic materials

This paper presents a new application of Automated Bonding Evaluation System (ABES) for studying the reactivity of adhesive–substrate combinations (adhesive–cork, impregnated paper–wood and laminate–wood); a new sample configuration and a new kinetic model are proposed. Isothermal bond strength development was plotted as a function of time for several platen temperatures and the kinetic parameters were computed from these plot families, for each type of adhesive and combinations. The methodology developed showed to have potential in quantitative screening of adhesives and operating conditions in industrial context (production of cork composites, melamine faced boards and high pressure laminates).

Cure Characteristics of Phenol-Formaldehyde Resin Catalyzed with Ba(OH)2

Phenol-formaldehyde resins are high performance wood adhesives, and are also used to impregnate base papers which are manufactured high-pressure laminates applied in furniture and interior decoration. In this investigation, PF resins catalyzed with Ba(OH)2 were studied. Both Ba(OH)2 content and F/P molar ratio were found to influence the cure rate. The cure rate of the Ba(OH)2 catalyzed PF resin was faster by 50% than that of ordinary PF resin at 150°C. The DSC results showed that the Ba(OH)2 catalyzed PF resin was cured at a lower temperature than the ordinary PF resin. And the IR results showed that the Ba(OH)2 catalyzed PF resin has higher degree of ortho-position coupling.

Factors affecting some quality properties of the decorative surface overlays

In this study, the influences of varnish and overlaying material types, structure of continuous pressed laminates (CPL) and resin mixture on the cigarette, scratch and abrasion resistances were investigated. Three-layered particleboard composites were overlaid with various decorative surface overlays (veneer, continuous pressed laminates, high-pressure laminates and finish foils). The results showed that the overlay and varnish types, and resin mixture used for the finish foil manufacturing were significantly found to be effective on the cigarette, scratch and abrasion resistances. While the lowest scratch and abrasion resistances were obtained from veneered boards, high-pressure laminates (HPL) had the highest values. Polyurethane based varnish showed higher resistances to the scratch and abrasion compared to cellulosic-based varnish. CPL structure was not found to be effective on these properties. The acrylic and urea mixture ratio used for the finish foil manufacturing was found to be effective on the abrasion and cigarette resistances. Increasing acrylic amount in the resin mixture statistically improved the quality properties of the finish foils. This study shows that end use applications of the overlaid panels are related to the overlay and varnish types, and resin mixture used for impregnating of the decor papers.

Electron beams in research and technology

Fast electrons lose their energy by inelastic collisions with electrons of target molecules forming secondary electrons and excited molecules. Coulomb interaction of secondary electrons with valence electrons of neighboring molecules leads to the formation of radical cations, thermalized electrons, excited molecular states and radicals. The primary reactive species initiate chemical reactions in the materials irradiated. Polymer modifications using accelerated electrons such as cross-linking of cable insulation, tubes, pipes and moldings, vulcanization of elastomers, grafting of polymer surfaces, processing of foamed plastics and heat shrinkable materials have gained wide industrial acceptance. A steadily growing electron beam technology is curing of paints, lacquers, printing inks and functional coatings. Electron beam processing offers high productivity, the possibility to treat the materials at normal temperature and pressure, excellent process control and clean production conditions. On an industrial scale the most important application of fast electrons is curing of 100% reactive monomer/prepolymer systems. Mainly acrylates and epoxides are used to formulate functional coatings on substrates such as paper, foil, wood, fibre board and high pressure laminates. A survey is given about the reaction mechanism of curing, the characterization of cured coatings, and of some industrial application.

Preparation of Binders from Inexpensive By-products for Use in High-Pressure Phenolic Laminates: Reactive Phenosolvan Pitch-Lignin Derived Products for Use in Impregnating Varnishes and Testing of 6-Ply Hessian-Paper Laminates

SYNOPSIS Equal mixtures of phenosolvan pitch and autohydrolysis bagasse lignin in the presence of either acid or alkaline catalyst and without catalyst were submitted to a thermal treatment stage at 230°C (Phenolation). Each of the phenolated products was mixed with phenol resol varnish (ratio 50: 50) for impregnation into 6-ply hessian Kraft paper laminates. Laminates impregnated with phenol resol and phenolated pitch/lignin with a hexamine hardener addition solely served as references. Laminates impregnated with each mixture produced adequate tensile and flexural strength, while the mixtures containing either the acid or alkaline phenolated product were superior in stiffness to phenol resol and the mixture without catalyst. All mixtures and the phenolated pitch/lignin with hexamine lacked the toughness of the phenol resol system.

Classification of reaction‐to‐fire of decorative high‐pressure laminates (HPL)

AbstractDecorative high‐pressure laminates (HPL) are used in many applications where their reaction‐to‐fire is of particular interest. They form finishes of walls and ceilings in buildings, ships and vehicles. Due to the different specifications and regulations in these fields, different grades of this largely standardized material have been tested worldwide with similar results. As a consequence, German and French building regulations state decorative high‐pressure laminates to be generally admissible on a minimum level without individual testing. This survey indicates their generic suitability in other fields, e.g. to have ‘low flame‐spread characteristics’ according to the International Convention for the Safety of Life at Sea.

Design of Plastics Structural Components: Proposed ASCE Manual

The content of the first four chapters of a forthcoming ASCE Engineering Manual for the Design of Plastics Structural Components is summarized and the scope of the entire Manual is presented in outline form. The manual will assist the engineer in designing plastics for structural applications. The first four chapters cover a summary of principal engineering plastics, reinforced plastics/composites, high-pressure laminates, and polymer concretes and their typical structural properties, descriptions of the more important fabrication processes, and their influence on design of structural components, a detailed consideration of mechanical behavior of plastics and composites and the structural criteria that are needed for design with these materials, and, finally, an exposition of overall design considerations that are particularly relevant to these materials. The concepts of viscoelastic and anisotropic structural behavior are introduced. The importance of considering effects of load duration and environmental exposure are explained.

An improved method for determining the wear of polymeric coatings

A modification on the Taber Abrader is described in which a 1 4 in steel ball is substituted for the conventional sandpaper wheel. As a result, the endpoint of the test becomes much clearer and the test data are suitable for quantitative interpretation. The modified test is applicable not only to high pressure laminates but also to a wide variety of plastics and coatings. Further modifications are proposed to convert the wear path to a straight line instead of the circle found on the Taber Abrader and to increase the load on the ball. These changes are expected to make the testing time comparable to the present sandpaper wheel method.

Wear behavior of high-pressure melamine-formaldehyde laminates

The wear process of melamine-formaldehyde resin reinforced with α-cellulose paper was studied using a ball and disc apparatus. The wear behavior was followed optically and the various stages were photographed. Three stages of wear were noted: 1. (1) the initial failure consisted of cracking and chipping most often above the point of intersection of the paper fibers with the laminate surface. Lines which formed the envelope of these failure points defined the boundaries of the wear track in stage 2. (2) which consisted of continued chip ejection until the entire surface of the track had been pitted. At that point the ball was seated in the track and in stage 3. (3) continued to cut a groove.