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Decorative laminates are the most important class of surface-finished engineered wood products. However, while there are numerous scientific publications published dealing with the technology of wood, wood-based products and also liquid coating systems, there is practically no scientific research work available in the field of paper-based laminates. In view of an ever increasing global competition it is time to systematically apply and pursue scientific approaches in this field. The present work is based on a knowledge-based manufacturing paradigm. The application of scientific methodology (e.g. instrumental analysis, process analytics, design of experiments, chemometrics, process modeling) to the preparation of decorative laminates covering the whole process chain from resin synthesis to paper impregnation and to final laminate should enable a targeted design of material functionality.
Silicones
(2014)
Silicones are found in a variety of applications with requirements that range from long life at elevated temperatures to fluidity at low temperatures. This chapter first considers silicone elastomers and their application in room temperature vulcanizing (RTV) and heat curing systems (HTV). Also, new technologies for UV curing are introduced. Coverage of RTVs includes both one-component and two-component systems and the different cure chemistries of each, and is followed by a separate discussion of silicone laminates. Due to the high importance of silicone fluids, they are also discussed. Fluids include polishes, release agents, surfactants, and dielectric fluids.
In the period from the 1950s to 2013, the American Food and Drug Administration (FDA) approved 1346 new molecular entities (NMEs) or new biologics entities (NBEs). On average, the approval rate was 20 NMEs per year. In the past 40 years, the number of new drugs launched into the market increased slightly from 15 NMEs in the 1970s to 25–30 NMEs since the 1990s. The highest number of new drugs approved by FDA was in 1996 and 1997, which might be related to the enactment of the Prescription Drug User Fee Act (PDUFA) in 1993.
Processing
(2014)
In this chapter, some relevant aspects and illustrative examples of online monitoring tools as the basis for process control in the manufacturing and processing of thermosetting resins are briefly discussed. In principle, any chemical or physical information made accessible by sensors can be used for online monitoring of resin formation, resin location in the mold, and resin cure. For instance, changes in the flow properties of the reaction mixture are often routinely recorded in dependence of the reaction time during resin synthesis as a measure for the degree of conversion of raw materials into macromolecules or oligomers by applying rheometry in an in-process environment. Typically, a small sample of the reaction mixture is by-passed, subjected to rheological measurement, and re-introduced into the bulk reactor. In a similar way, pH measurements, turbidimetric measurements, or other analyses are performed. Although rheometry may not always be suitable for following resin cure (especially in cases where there is a very rapid increase in viscosity after initiation of the cure), [1] naturally, the method can in principle also be used in the subsequent processing of the thermosets, for instance in the curing of wood glue applied to wood specimen [2]. Similarly, pH changes during thermoset curing can be followed. Hence, an encyclopedic and comprehensive approach to present process control methods would systematically proceed according to the involved physical measurement principle. However, since only a very Brief sketch of means for monitoring thermoset processing can be given here, only a small, personally biased selection of important methods and application examples is addressed in the following sections. These examples hopefully illustrate some of the general strategies and solutions to problems that are typically encountered when processing thermosets.
Unsaturated polyester resins (UPR) and vinyl ester resins (VER) are among the most commercially important thermosetting matrix materials for composites. Although comparatively low cost, their technological performance is suitable for a wide range of applications, such as fiber-reinforced plastics, artificial marble or onyx, polymer concrete, or gel coats. The main areas of UPR consumption include the wind energy, marine, pipe and tank, transportation, and construction industries. This chapter discusses basic UPR and VER chemistry and technology of manufacturing, and consequent applications. Some important properties and performance characteristics are discussed, such as shrinkage behavior, flame retardance, and property modification by nanoparticles. Also briefly introduced and described are the practical aspects of UPR and VER processing, with special emphasis on the most widely used technological approaches, such as hand and spray layup, resin infusion, resin transfer molding, sheet and bulk molding, pultrusion, winding, and centrifugal casting.
Three different polyols (soluble starch, sucrose, and glycerol) were tested for their potential in the chemical modification of melamine formaldehyde (MF) resins for paper impregnation. MF impregnated papers are widely used as finishing materials for engineered wood. These polyols were selected because the presence of multiple hydroxy groups in the molecules was suspected to facilitate cocondensation with the main MF framework. This should lead to good resin performance. Moreover, they are readily produced from natural feedstock. They are available in large quantities and may serve as economically feasible, environmentally harmless alternative co-monomers suitable to substitute a portion of fossil-based starting material. In the presented work, a number of model resins were synthesized and tested for covalent incorporation of the natural polyol into the MF Framework. Spectroscopic evidence of chemical incorporation of glycerol was found by applying by 1H, 13C, 1H/13C HSQC, 1H/13C HMBC, and 1H DOSY methods. It was furthermore found that covalent incorporation of glycerol in the network took place when glycerol was added at different stages during synthesis. Further, all resins were used to prepare decorative laminates and the performance of the novel resins as surface finishing was evaluated using standard technological tests. The technological performance of the various modified thermosetting resins was assessed by determining flow viscosity, molar mass distribution, the storage stability, and in a second step laminating impregnated paper to particle boards and testing the resulting surfaces according to standardized quality tests. In most cases, the average board surface properties were of acceptable quality. Our findings demonstrate the possibility to replace several percent of the petrol-based product melamine by compounds obtained from renewable resources.
Crosslinked thermoplastics
(2014)
Cross-linked thermoplastics represent an important class of materials for numerous applications such as heat-shrinkable tubing, rotational molded parts, and polyolefin foams. By cross-linking olefins, their mechanical performance can be significantly enhanced. This chapter covers the three main methods for the cross-linking of thermoplastics: radiation cross-linking, chemical cross-linking with organic peroxides, and cross-linking using silane-grafting agents. It also considers the major effects of the cross-linking procedure on the performance of the thermoplastic materials discussed.
Mass-customization is a megatrend that also affects the wood industry. To obtain individually designed laminates in batch size one efficient printing and processing technologies are required. Digital printing was envisaged as it does not depend on highly costly printing cylinders (as used in rotogravure printing) and allows rapid exchange of the printing designs. In the present work, two wellestablished digital printing approaches, the multi-pass and the single-pass technique, were investigated and evaluated for their applicability in decorating engineered wood and low-pressure melamine films. Three different possibilities of implementing digital printing in the decorative laminates manufacturing process were studied: (1) digital printing on coated chipboard and subsequently applying a lacquered top-coat or melamine overlay (designated as “direct printing”, since the LPM was the printing substrate), (2) digital printing on decorative paper which was subsequently impregnated before hot pressing (designated as “indirect printing, variant A”) and (3) digital printing on decorative paper with subsequent interlamination of the paper between impregnated under- and overlay paper layers during the pressing process (designated as “indirect printing, variant B”). Due to various advantages of the resulting cured melamine resin surfaces including a much better technological performance and flexibility in surface texture design, it was decided to industrially further pursue only the indirect digital printing process comprising interlamination and the direct printing process with a melamine overlay-finishing. Basis for the successful trials on production and laboratory scales were the identification of applicable inks (in terms of compatibility with melamine resin) and of appropriate printing paper quality (in terms of impregnation and imprinting ability). After selection and fine tuning of suitable materials, the next challenge to overcome was the initially insufficient bond strength between impregnated overlay and the ink layers which led to unsatisfactory quality of the print appearance and delamination effects. However, the optimization of the pressing program and the development of a modified impregnation procedure for the underlay and overlay papers allowed the successful implementation of digital printing in the production line of our industrial partner FunderMax.
Allyls
(2014)
This chapter addresses the importance and usage of the commercially low volume thermoset plastics group known as allyls. The three significant sub-elements of this group are poly(diallylphthalates), poly(diallylisophthalates), and poly(allyldiglycol carbonate). Chemistry, processing, and properties are also described. Allyl polymers are synthesized by radical polymerizations of allyl monomers that usually do not produce high-molecular-mass macromolecules. Therefore, only a few specific monomers can produce thermosetting materials. Diallyldiglycolcarbonate (CR-39) and diallylphthalates are the most significant examples that have considerably improved our everyday life.
This review gives a short overview of the physical processes involved in the formation of the polyelectrolyte multilayers (PEMs) and their destruction. These two processes are vital for the formation of PEMs with desired physical and chemical structures, and for loading them with active substances and their spatial controlled release. It includes a survey of the physical and chemical properties that are key points for controlling film nanostructure in relation to biological processes and different possibilities for controlling cell behavior by means of film composition, bioactivity, mechanical properties, and three-dimensional organization.