Low Pressure Lamination Research Articles

Preparation and Characterization of Melamine–Benzoguanamine–Formaldehyde Resins and Their Flame-Retardant Properties in Impregnated Paper for Low Pressure Laminates

Preparation and Characterization of Melamine–Benzoguanamine–Formaldehyde Resins and Their Flame-Retardant Properties in Impregnated Paper for Low Pressure Laminates

Impact of condensation degree of melamine-formaldehyde resins on their curing behavior and on the final properties of high-pressure laminates

Melamine-formaldehyde is the most common resin used in the production of high-pressure laminates and low-pressure laminates (melamine impregnated paper), due to its properties of durability, good fire, and heat resistance and good moisture resistance. High-pressure laminate is a common choice for horizontal and vertical applications in the construction and furniture industries, thanks to its durability and versatility. The manufacture of such laminates commonly starts with the impregnation of decorative and kraft papers with thermosetting resins and after a drying process, the impregnated paper sheets are bonded together by high pressure and temperature pressing. The aim of this work was to evaluate the influence of the melamine-formaldehyde resins condensation degree after synthesis on high-pressure laminates performance. For that purpose, melamine-formaldehyde resins with different condensation degree were synthetized and characterized. Fourier-transform infrared–attenuated total reflection spectroscopy and dynamic mechanical analysis were used to study the chemical and mechanical cure of melamine-formaldehyde resins. Melamine-formaldehyde condensation degree has shown to have influence on resin pot-life, on characteristic reaction temperatures, on the degree of cross-linking achieved, and finally on the surface quality of high-pressure laminates.

Effects of surface laminate type and recycled fiber content on properties of three-layer medium density fiberboard

ABSTRACTHigh global production of medium-density fiberboard (MDF) in recent years could generate an equal quantity of waste MDF at the end of its service life, requiring recycling of waste MDF instead of landfilling or incineration. This study investigated effects of the addition of recycled fiber (RF) obtained from surface laminated MDFs with three different materials to the properties of three-layer recycled MDF (rMDF). Three types of surface laminates such as low-pressure laminate, polyethylene terephthalate, and polyester coating were hammer milled, and then went through a patent-pending fiber recovery system to obtain the resultant RFs that were added to the core layer of rMDF. These RFs at three contents (10, 20, and 30%) were blended with 12% of urea-formaldehyde (UF) resin prior to hot-pressing. Statistical analysis showed that the best internal bonding strength, modulus of rupture, and modulus of elasticity of rMDF panels were obtained for LPL-rMDF with a 20% RF content. Thickness swelling, water absorption, and formaldehyde emission of rMDF were reduced by increasing the RF content. These findings suggest that a minimum RF content of 20% can be replaced with virgin fibers for the rMDF manufacture, indicating the feasibility of recycling waste laminated MDF into three-layer rMDF.

Primerjava lastnosti obložene cementno-iverne plošče in površinsko obdelane furnirne plošče

In this study, we produced two types of claddings, representing the element of the ventilated façade. The first façade cladding was a cement-bonded particleboard, surfaced with a low-pressure laminate, while the second was a waterproof plywood board, coated with a stain-coating system. Both types of façade claddings were exposed to processes of artificial accelerated aging and temperature cycling tests, as well as to biotic factors, in order to simulate the conditions in real use. Changes in climatic conditions and other factors of the performed tests had a larger influence on the behaviour and properties of the surface finished plywood board. Both types of composites were not susceptible to infection with wood decay and blue-stain fungi. According to the results of the research, both types of claddings are suitable for the intended use as the outer element of a ventilated façade.

Dynamic Behavior Analysis of Non-Contacting Hydrodynamic Finger Seal Based on Fluid-Solid-Interaction Method

Finger seal is an advanced compliant seal and can be utilized to separate high (HP) and low pressure (LP) zones in high speed rotating shaft environment. The work to be presented concerns the dynamic behavior of a repetitive section of a two-layer finger seal with high-and padded low-pressure laminates. The dynamic performance of the finger seal are analyzed by the coupled fluid-solid-interaction (FSI) simulations. By using the commercial software ANSYS-CFX, the numerical simulation results of interactions between the gas flow and fingers structural deformation are described when the radial periodic excitation from the shaft applies to the finger seal. And the gas film loading capacity, gas film stiffness and leakage varied with time are put forward in different working conditions. Compared with the dynamic performance analysis results based on equivalent dynamic method, the FSI dynamic analysis shows some different characteristics which are more accordance with actual circumstance. Moreover, it is shown that under low pressure differential and high rotation speed the non-contacting finger seal with advance features both in sealing effectiveness and potential unlimited life span can be obtained by rational structure design. But for the non-contacting finger seal with circumferential convergent pad working in high pressure and low rotating speed conditions, it is difficult to improve the sealing performance by the way of changing the structure parameters of finger seal. It is because the high pressure plays a major role on this sealing situation.

Formaldehyde Emission of Wood-Based Composite Panels with Different Surface Lamination Materials Using Desiccator Method

Wood-based composite panels such as plywood, particleboard (PB), or medium density fiberboard (MDF) are mostly used in the lamination on their surface for the manufacturing of furniture, or interior building products, the concern on the formaldehyde emission (FE) from the surface laminated wood panels is increasingly attracting attentions from the public. Thus, this study was conducted to understand influence of surface laminating materials to the FE from PB and MDF with or without edge sealing, using 24-hour desiccator method. Both PB samples that had been laminated on their surface with low-pressure laminate (LPL) or polypropylene (PP) film and MDF that had been treated with poly(vinyl chloride) (PVC) or coating were tested for the FE with or without edge sealing. As expected, the FE of PB with the sealed edges decreased to 37.4% and 80.7% with the LPL and PP lamination, respectively. The surface laminated MDF with the sealed edges also showed a decrease in the emission up to 57.8% and 54.3%, with the PVC lamination and coating, respectively. However, the coated MDF samples showed 5.3% increase in the emission when their edges were not sealed, indicating a FE form the solvent used for coating. These results showed that the type of surface lamination materials on wood-based composite panels has a great impact on their resultant FE, indicating that the influence of surface laminating materials should be taken into consideration for the formaldehyde mission measurement.

Influence of Cold Low Pressure Lamination Parameters on the Joining of Low Temperature Co‐Fired Ceramics Green Tapes and Sintered Alumina Substrates

In this study, laminates consisting of sintered alumina substrates and green Low Temperature Co‐fired Ceramics (LTCC) tapes have been produced via Cold Low Pressure Lamination which is based on adhesive tapes for joining of layers at room temperature and pressures <5 MPa. The influences of lamination parameters such as temperature, pressure, and time on the quality of the green and sintered multilayer stack have been determined. If the bottom LTCC layer of an alumina–LTCC–LTCC laminate is metallized by screen printing defects such as crack formation can occur due to stress formation caused by constrained sintering. By adapting the lamination parameters, these stresses can be avoided. Another defect observed is cavities which form along the printed circuit lines. This type of defect is caused by the shrinkage of the circuit line width during firing; by reducing the height of the conductor line during screen printing, the cavity size can be reduced. In addition, different screen‐printed metallization layouts have been tested to determine the influence of line and spaces on the quality of sintered laminates.

Manufacturing of Touch Sensors Integrated in Decorative Laminates for Furniture Surface

This paper reports an application example of printed electronics function on paper. We laminated printed conductive areas into a standard low pressure laminate structure on chipboard, together with a digitally printed decorative surface layer. Thus a demonstrator of customized touch sensors in furniture was realized.

Fine structuration of low-temperature co-fired ceramic (LTCC) microreactors.

The development of microreactors that operate under harsh conditions is always of great interest for many applications. Here we present a microfabrication process based on low-temperature co-fired ceramic (LTCC) technology for producing microreactors which are able to perform chemical processes at elevated temperature (>400 °C) and against concentrated harsh chemicals such as sodium hydroxide, sulfuric acid and hydrochloric acid. Various micro-scale cavities and/or fluidic channels were successfully fabricated in these microreactors using a set of combined and optimized LTCC manufacturing processes. Among them, it has been found that laser micromachining and multi-step low-pressure lamination are particularly critical to the fabrication and quality of these microreactors. Demonstration of LTCC microreactors with various embedded fluidic structures is illustrated with a number of examples, including micro-mixers for studies of exothermic reactions, multiple-injection microreactors for ionone production, and high-temperature microreactors for portable hydrogen generation.

Evaluation of Formaldehyde Emissions and Combustion Behaviors of Wood-Based Composites Subjected to Different Surface Finishing Methods

To use wood-based panels as a final product, they must undergo surface finishing via various processes, such as low pressure laminate (LPL), polyvinyl chloride (PVC), coating paper (CP), direct coating (DC), or veneer overlay/UV coating (VO-UVC). Tests were conducted to look for any reduction of formaldehyde emissions and in combustion behaviors with the use of five different surface finishing methods. To determine formaldehyde emissions, the desiccator method was used according to the Korean Standard KS M 1998. The combustion behaviors of wood-based panels were investigated using a cone calorimeter. The formaldehyde emissions of VO-UVC were lower than those of the other methods. In the burning tests, the heat release rate (HRR) with DC was higher than that with the other methods. The mass loss rate (MLR) when the product with DC was burned was higher than that for the other finishing materials.

In Situ Characterization of the Sintering Behavior of LTCC Laminates with Embedded Cavities by High Temperature Laser Profilometry

Three-dimensionally structured LTCC multilayer with channels and inner cavities are required for numerous applications like microreactors, microfluidic systems or sensors. For the performance of such devices, the dimensional accuracy of the embedded structures is crucial. In the green state, the desired structures can be precisely implemented in the LTCC tapes by laser cutting, punching or milling. Unfortunately, during lamination and sintering, shape integrity of cavities and channels is notably affected by warpage and deformation. To investigate the sintering behavior of structured LTCC laminates, a newly developed High Temperature Laser Profilometer (HTLP) can be used. The HTLP allows 3D in-situ shape detection of flat ceramic samples and tapes all along the sintering process. It is applicable for temperatures up to 1000 °C and sample sizes up to 200 mm × 200 mm × 10 mm. During a measurement, the rotating sample is scanned spirally by a linearly moving laser distance sensor through a slot in the furnace top wall. Distance and position values deliver a 3D surface image of the sample. Current lateral dimensions, which are determined by sintering shrinkage, can be measured continuously. Local deformation and warpage can be visualized time- and temperature-resolved. This new method was used, to analyze the sintering behavior of LTCC multilayer laminates containing large size cavities. These were fabricated out of punched green sheets by low pressure lamination without inserts. Samples with cavities of varying cross sections, as well as cavities with and without connection to the surface were observed.

Joining of Sintered Alumina Substrates and LTCC Green Tapes via Cold Low Pressure Lamination

In microelectronics there is a continuous trend for devices of higher integration and improved heat dissipation. For the manufacture of ceramic based microelectronic devices the following technologies can be applied. Thick-film hybrid technology uses sintered ceramic substrates, mostly Al2O3, which are screen printed with functional pastes, followed by firing at 850 °C. Alumina substrates provide very good heat conductivity (25 W/mK), but there are only two sides to carry a metallization. An improved miniaturization can be accomplished by multilayer systems using the LTCC technology. LTCC devices are manufactured by screen-printing, stacking and lamination of ceramic green tapes, followed by co-firing. A drawback of LTCCs is their low heat conductivity (3 W/mK) due to their high glass content. By combining hybrid and LTCC technology the advantages of both methods like good thermal conductivity and high multilayer integration, can be joined. Because the failure rate is too high to laminate green tapes on sintered ceramic substrates via thermo compression, Cold Low Pressure Lamination (CLPL) has been used as an alternative lamination process. CLPL is a lamination method, where the joining of the components is performed at room temperature by application of very low pressure (<5 MPa) by using a double sided adhesive tape. During heat treatment the adhesive film keeps the tapes together until the adhesive is completely decomposed; during further temperature increase the tapes are joined by sintering. The paper describes the materials used and processing steps to join the sintered material with the green tapes and discusses effects which occur during firing. These effects like edge curl and crack formation are mainly due to stresses which occur during constrained sintering. Their control can be influenced by changing process parameters.

Effect of surface laminate type on the emission of volatile organic compounds from wood-based composite panels

As a part of understanding the influence of wood-based panels on indoor air quality of a building, this study examined the effects of laminate type on the emission of volatile organic compounds (VOCs) such as formaldehyde, toluene, and total VOCs (TVOCs) from particle board (PB) and medium density fiberboard (MDF) panels, using a 20-L small chamber method. Five different types of surface laminates, including three types of surface overlays such as low pressure laminate (LPL), poly(vinyl chloride) (PVC) film, and urethane coated paper (UCP), as well as two types of surfaces coatings, i.e. direct coating (DC) and ultra-violet coating (UVC) were applied to the veneer bonded to a surface of PB and MDF panels that were of different grades with respect to formaldehyde emission (FE) such as E 0, E 1, and E 2 before surface lamination. As expected, the FE grade strongly affected the FE of panels, regardless of types of panel and laminate. All types of surface laminations dramatically reduced the FE compared to the control. However, the surface laminations by overlay significantly decreased the emission of TVOCs and toluene while both types of surface coatings greatly increased the emission of TVOCs and toluene. In particular, styrene was the main component of TVOCs from the DC sample (about 87%), while toluene was the main species of TVOCs from the UVC sample (about 73%). When two different ways of sample preparation (i.e., single- or all-surface exposure) were compared, the FE of the MDF sample was influenced by the surface exposure type. But TVOCs and toluene emissions were independent of the FE grade and the sample preparation. These results suggest that a proper selection of the surface laminate for wood panels has a significant impact on indoor air quality of a building.

Transfer of highly porous nanoparticle layers to various substrates through mechanical compression

A new two-step layer transfer process is introduced that is capable of fabricating mechanically stabilized highly porous nanoparticle layers on various substrates. In a first step titanium dioxide nanoparticles were synthesized with Flame-Spray-Pyrolysis and accumulated on a filter paper in the gas phase. In a second step this highly porous filter cake is subsequently transferred to a final substrate via low pressure lamination at room temperature. This leads to mechanical restructuring and stabilization of the porous layer. Pore size analysis indicates homogenization of the layers through rearrangement of the aggregates inside the layers that increases with applied pressure. Additionally, the Young's moduli of the layers were quantified through Colloidal-Probe-Technique indentation measurements with an Atomic-Force-Microscope. The highest lamination pressure of 2.5 MPa resulted in triplication of the Young's modulus. The results show that our novel two-step layer transfer process leads to mechanically stabilized layers that preserve their high porosity. Through the decoupling of the high temperature nanoparticle synthesis and the final substrate the process also enables the possibility to apply temperature sensitive substrates such as polypropylene foil.

Realisation of Large Cavities in Multilayer Ceramics by Cold Low Pressure Lamination and Their Characterisation by μCT

In microelectronics the ceramic multilayer technology is frequently used as it allows a precise and yet flexible production of MEMS, microelectronic devices, micro reactors or devices for micro fluidics. During production of those multilayer structures the single layers are typically laminated by thermo-compression. However, large cavities cannot be realised using thermo-compression without adding sacrificial fillings. In contrast, the cold low pressure lamination (CLPL) technique allows lamination at room temperature without applying a high pressure. As in this lamination technique no mass flow occurs, internal cavities are not destroyed during the lamination step. In this study, commercially available LTCC green tapes were structured using a milling plotter with a high frequency spindle. Different process parameters (milling speed, spindle frequency) were evaluated regarding the accuracy of shape and quality of the channel edge. Channels with various dimensions (2.5 - 15 mm width and 30 mm length) were milled into the green tapes. Subsequently, the green tapes were laminated using the CLPL technique. With CLPL adjacent ceramic green tapes are joined by a double sided adhesive tape, which is applied by a soft roller. By alternately applying green (structured or unstructured) and adhesive tapes multilayer structures with internal cavities are formed. For characterisation of the sintered LTCC structures μCT (computed tomography) was used to analyse the internal structure without destroying the sample. Influence of sintering regime on deformation was evaluated. It was shown that milling of green tapes in combination with CLPL is a suitable method to fabricate internal cavities in LTCC multilayer structures.

Lamination of LTCC at low pressure and moderate temperature using screen-printed adhesives

In this work, we investigate a new method of low-pressure lamination of low-temperature cofired ceramic (LTCC) tapes, by pre-coating with specially-formulated adhesive layers. This allows fabrication of intricate structures that would be destroyed by high lamination pressures, yet preserves compatibility with standard processing operations, such as blanking, laser cutting, punching, via filling and screen printing. Techniques proposed previously are application of adhesive tapes, solvents or glues. These methods are applied after the tape processing steps and therefore require an extra operation in the processing chain, which may be unpractical, especially if the tape is very thin has been extensively cut. In our procedure, the adhesives are printed and dried on the blanked tape before any other operation, with the drying step also useful for pre-conditioning the tapes, which may then be stored as "standard" blanks. The adhesives are formulated to have low tack at room temperature, making them compatible with standard processing, but to become very soft at 50–60°C, allowing lamination at low pressures. Compatibility with different tape materials is investigated, and the requirements for adequate adhesive formulation are discussed.

Solvent-assisted low pressure room temperature lamination of low temperature cofirable ceramic green tapes for formation of embedded micro channels

Low temperature cofired ceramic substrates are becoming increasingly attractive for high density electric circuits and microsystems. Embedded micro patterns such as channels and cavities in ceramic substrates are indispensable for circuit cooling and media transportation. One of process challenges is how to make these embedded micro channels and cavities, which would be collapsed or deformed under conventional lamination. This paper reports on a novel solvent-assisted lamination that could provide low pressure and room temperature lamination of ceramic green tapes. The solvent used in this study was turpentine oil, which demonstrated a proper capability of dissolving polymeric additives on surface of green tapes without obviously changing the distribution of ceramic particles. Procedures for forming embedded micro channels in ceramic green substrates include micro embossing to create open channels, coating of turpentine solvent, followed by low pressure and room temperature lamination. Embedded micro channels with channel width ranging from 25 to 1,000 μm were obtained in ceramic green substrates; Depths of embedded channels shrank by 3–12% versus embossed depths due to turpentine-assisted lamination. The ceramic green substrates with embedded channels were then sintered under a standard cofiring process.

Processing procedures for the realization of fine structured channel arrays and bridging elements by LTCC-Technology

This report deals with technological procedures to provide channel partition walls of minimum width inside of Low Temperature Co-fired Ceramics (LTCC) micro fluidic devices demonstrated by means of the fabrication of parallel closely-spaced channels which may act as a specific functional part of a fluidic heat exchanger. Furthermore, the realization of single layer bridging elements inside of channels is discussed. Such an element may be introduced as a delicate sensor substrate providing adequate thermal insulation and low thermal mass as well. The technological processing steps under consideration start with laser micromachining of green ceramic tapes using Nd-YAG-laser equipment and are followed by a modified low-pressure lamination step comprising the application of appropriate adhesives and the incorporation of polymer sacrificial volume materials (SVMs). Consequently, the increased fraction of involved organics requires an adequate adaptation of the firing process to provide a residue-free burnout. Great attention is paid to the prevention of channel cross-section distortion and to the integrity of structures, verified by optical inspection of microsectioned samples. The optimized processing procedures enable the fabrication of channel arrays with a partition wall thickness as small as 100 μm, while single layer bridging elements may span a channel width of 4 mm.

Manufacture of 3D structures by cold low pressure lamination of ceramic green tapes

3D multilayer devices were generated by Laminated Object Manufacturing (LOM), a well-known rapid-prototyping technology. Divergent from this method, commercial ceramic green tapes were used which were laminated by Cold Low Pressure Lamination (CLPL). In contrast to thermo-compression, which works at pressures and elevated temperatures, CLPL allows to join particularly fine, complex structures with cavities or undercuts, because no mass flow occurs. This technique is based on gluing the adjacent tapes by means of an adhesive film at room temperature under a low pressure. After binder burnout and sintering the ceramic laminate has a homogenous and dense microstructure free of interfaces. This modified LOM technique is particularly suitable for the production of Micro Electro Mechanical Systems (MEMS). In the given paper commercial Low Temperature Co-fired Ceramic (LTCC) green tapes were used, which were structured by means of a high-frequency milling plotter and laminated by using CLPL. Various 3D devices of different shape with inlying cavities were manufactured. The quality of the fired and unfired structures of the devices were characterised by different methods and show a high quality surface of the multilayer structures. Process aspects of the CLPL technique are discussed. The results demonstrate the advantages of this method for the fabrication of MEMS.

Mechanical behavior of glass polymer multilayer composites

To identify the best reinforcement condition for development of tough glass polymer multi-layer composites (GPMLC) with high failure strain, two such model composite structures were developed. Soda–lime–silica glasses of two different thicknesses viz (A—1.01 mm and B—1.17 mm) were used as the matrix layers. The A-glass and B-glass based GPMLC samples were prepared by a novel, low pressure lamination technique applied to the alternating planar structure of the matrix and reinforcing phases. These GPMLC materials were fabricated with and without a thin sprayed layer of kerosene, between the glass layer and the reinforcing layer in the interface where; the interface was either epoxy (a thermosetting resin) or polyvinyl butyral (PVB, a thermoplastic resin). The GPMLC samples which exhibited stepped load—displacement behaviour in the most pronounced fashion, had the thermoplastic resin at the interface. Most of these GPMLC samples had a thin layer of kerosene intentionally introduced between the glass layer and the reinforcing polymer layer such that a weak interface is obtained. Fractographic evidence suggested that more of controlled delaminaton cracking occurs in such samples. Apart from the chemical nature of the reinforcing polymer phase, the interfacial layer thickness (h i ) and the interfacial shear stress (τ xy ) were found out to have significant influence on the specific failure load and the failure stress of the current glass polymer multi-layer composites.