Hard Coat Research Articles

Experimental study on buckle evolution of thin inorganic layers on a polymer substrate

Abstract In this paper the behavior of a 250 nm and a 350 nm thick Indium tin oxide (ITO) layers deposited on a 200 μm thick high temperature aromatic polyester substrate (Arylite™) and spin coated with a 3 μm silica–acrylate hybrid coating (Hard Coat) is discussed. In-situ optical microscopy of the layered structures under uniaxial compressive strain was used to determine the buckle delamination rate at different applied strains. The effect of applied uniaxial compressive strain and layer thickness on the evolution of buckle width and height was investigated. The biaxial-residual stress, uniaxial compressive stress, poor adhesion at the interface and Poisson’s ratio are believed to be responsible for the formation of telephone-cord buckling.

Seed Germination and Seedling Emergence of Scotch Broom (Cytisus scoparius)

Scotch broom is a large, leguminous shrub that has invaded 27 U.S. states. The species produces seeds with a hard coat that remain viable in the soil for years. Growth-chamber studies were conducted to determine effects of temperature regime and cold-stratification period on seed germination. Seedling emergence, mortality, and biomass also were studied in response to sulfometuron and metsulfuron herbicides and variation in soil texture and watering regime. Germination was greatest for a dark/light temperature regime of 15/20 C. Initial rates of germination increased as stratification period was varied from 0 to 60 d, but final germination after 90 d did not differ significantly among periods. Applied alone or in combination, sulfometuron and metsulfuron decreased biomass and increased mortality of seedlings. Mortality from simulated soil drought was greater in the presence versus absence of sulfometuron (20 and 6% mortality, respectively) probably because the herbicide reduced root biomass by 58 to 95%. Invasiveness of Scotch broom is facilitated by a prolonged period of germination across a broad temperature range. Increased control of Scotch broom seedlings with sulfometuron is likely if application is timed to expose recently emerged seedlings to developing conditions of soil drought.

Indentation as a technique to assess the mechanical properties of fallback foods

A number of living primates feed part-year on seemingly hard food objects as a fallback. We ask here how hardness can be quantified and how this can help understand primate feeding ecology. We report a simple indentation methodology for quantifying hardness, elastic modulus, and toughness in the sense that materials scientists would define them. Suggested categories of fallback foods-nuts, seeds, and root vegetables-were tested, with accuracy checked on standard materials with known properties by the same means. Results were generally consistent, but the moduli of root vegetables were overestimated here. All these properties are important components of what fieldworkers mean by hardness and help understand how food properties influence primate behavior. Hardness sensu stricto determines whether foods leave permanent marks on tooth tissues when they are bitten on. The force at which a food plastically deforms can be estimated from hardness and modulus. When fallback foods are bilayered, consisting of a nutritious core protected by a hard outer coat, it is possible to predict their failure force from the toughness and modulus of the outer coat, and the modulus of the enclosed core. These forces can be high and bite forces may be maximized in fallback food consumption. Expanding the context, the same equation for the failure force for a bilayered solid can be applied to teeth. This analysis predicts that blunt cusps and thick enamel will indeed help to sustain the integrity of teeth against contacts with these foods up to high loads.

The adhesion of SiN x thin layers on silica–acrylate coated polymer substrates

Plasma Enhanced Chemical Vapor Deposition (PECVD) was used to grow 200, 300 and 400 nm thick silicon nitride layers (SiN x ) on a high temperature aromatic polyester substrate spin coated with a silica–acrylate hybrid coating (hard coat). Layers deposited without oxygen plasma treatment remained attached to the substrate, while spontaneous buckle delamination of the layer deposited with oxygen plasma treatment was observed directly after layer deposition. This effect was investigated using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). SIMS analyses showed a considerable increase of silicon oxide by exposing the substrate to oxygen plasma treatment, while AFM showed an increased roughness. Bright-field transmission electron micrographs show the presence of a particulate SiO 2 layer. The oxygen plasma treatment thus removes the acrylate from the hard coat layer leaving behind the SiO 2 particles leading to lower adhesion and thus to spontaneous buckle delamination.

A hard coat, a tough choice? The effects of host seed morphology and mechanics on the egg laying behaviour of the bruchid beetle (Callosobruchus maculatus)

This study investigated whether the egg laying behaviour of Callosobruchus maculatus, an important storage pest of leguminous seed crops, was related to the mechanical properties of the host seed. The hypothesis was that females avoid laying eggs on seeds with particularly tough seed coats and hard cotyledons to reduce the resistance their larvae are subjected to when they bore into the seed to complete their development. Females were presented with seeds from three leguminous species: Vigna unguiculata, V. angularis and V. radiata. The distribution of oviposition sites on the seed's surface was related to the morphology and mechanical properties of the seed. Vickers microhardness and fracture tests were used to investigate regional variation and compare the properties of seeds with and without eggs adhered to their surface. There were no significant regional differences in the hardness of the cotyledon material along the longitudinal axis of the seed (P > 0.05). However, there were significant differences between the mechanical properties of the seed coat and the cotyledons; in V. unguiculata the seed coat was tougher, 1249 ± 80.8 J m−2, than the cotyledons, 402 ± 30.0 J m−2 (P 0.05). Mechanical data are discussed in relation to the egg laying behaviour of C. maculatus.

New hard coat insulation

New hard coat insulation

Numerical analysis of delamination and cracking phenomena in multi-layered flexible electronics

The first part of this paper deals with the analysis of layer buckling and delamination of thin film multi-layer structures that are used in flexible display applications. To this end, 250 nm thick indium tin oxide (ITO) layers have been deposited on a 200 μ m thick high temperature aromatic polyester substrate (Arylite ™ ) with a 3 μ m silica–acrylate hybrid hard coat (HC). Typical buckle morphologies are determined from two-point bending experiments, in which buckle geometries are measured after straightening of the sample. Finite element simulations have been performed to estimate the corresponding interface properties and compressive strains in the layers, and to illustrate the effect of sample straightening on the buckle geometry. The second part considers the fracture sensitivity analysis of an active matrix Thin Film Transistor (TFT) display containing 512 × 256 pixels, with a typical pixel dimension of 160 × 160 μ m . Due to the large scale differences between the display and the TFT patterning a multi-scale modelling framework has been developed, which allows to include realistic material stacks and a detailed pixel geometry. The resulting patterning effect shows an anisotropic behaviour at both the pixel level and the global display level due to the multi-scale approach. Using the Area Release Energy (ARE) method an energy-based failure criterion has been utilised to analyse cohesive failure at several (critical) locations in the pixel geometry. Specifically, the sensitivity to tunnelling cracks in the dielectric layers is considered, which have been experimentally observed in comparable TFT samples that are subjected to tension. This local failure analysis allows for the identification of critical regions within the pixel geometry, which strongly depend on the location within a pixel.

Manufacturing Process for Low Cost Dual Layer Blu-ray Disc Read-Only Memory Media Based on the “All Spin Method”

To achieve low-cost Blu-ray disc (BD) media, a test line for dual layer media based on the “All Spin Method”, which we have previously proposed, was fabricated. All transparent layers (the space layer, the cover layer, and the hard coat) were made of inexpensive UV resin by spin coating. Dual-layer BD read-only memory (BD-ROM) media were manufactured with a cycle time of 4 s, and the characteristics of the media were observed. The results indicated that (1) the variation in total thickness of the transparent layers was within ±2 µm; (2) tilt properties after sudden environmental change and storage at high temperatures were good; (3) reproduced signals showed good jitter values and symbol error rate (SER); (4) reproduced signals were not degraded even after a storage test of 200 h at 80 °C and 85% relative humidity (RH). We have thus confirmed that the manufacturing line employing the All Spin Method has potential for mass production of low cost BD media. The All Spin Method is adaptable not only to the manufacture of BD-ROM but also BD-R (recordable) and BD-RE (rewritable), so it can contribute to decreasing the costs of all types of BD media.

P‐63: A New Transparent Plastic Substrate having High Heat Resistance and Low Retardation for Flexible Displays

AbstractWe have been developing a new transparent plastic substrate for flexible displays. The plastic substrate (OPS substrate) is composed of a newly developed base film (OPS film) and hard coat layers. The OPS substrate has excellent physical properties such as high transparency, low retardation and high heat resistance over 200°C. The coefficient of thermal expansion (CTE) is relatively low as 40–45ppm. The dimensional changes under various conditions including temperature and humidity were directly observed by using CCD camera.The electrical properties of the OPS substrate sputtered Indium Tin Oxide (ITO) at various temperatures were evaluated. The OPS substrate sputtered ITO at 200°C shows low sheet resistance as 10Ω/□ and it is almost same as that of glass substrate sputtered ITO under the same condition.

Effect of ingestion byDrepanoptila holosericea(Columbidae) on the seed germination ofSantalum austrocaledonicum(Santalaceae)

Santalum austrocaledonicumVieill. (Santalaceae) is a small tree endemic to New Caledonia and Vanuatu, well-known for the highly priced aromatic oil of its heartwood (Nasi & Ehrhart 1996). In New Caledonia, sandalwood grows on Loyalty Islands, the Isle of Pines and Grande-Terre (Bottinet al. 2006). The tree produces single-seeded fleshy drupes, which turn dark-red at maturity. Sandalwood seeds are dormant because of their hard coat and germinate only on physical scarification, or after removing the coat (Chauvin & Ehrhart 1998). In natural habitats, such seeds need further processing to relieve dormancy and promote germination, within a period where there is a good chance of successful seedling establishment (Murdoch & Ellis 2000).

Synthesis of organic–inorganic hybrid polymeric nanocomposites for the hard coat application

AbstractAn organic–inorganic hybrid polymeric nanocomposite has been synthesized for making UV‐curable hard coats. This nanocomposite consists of nano‐sized colloidal silica functionalized with vinyltriethoxysilane (VTES) and dendritic acrylic oligomers (DAO) which have been formed earlier via a reaction of ethylenediamine (EDA) with trimethylopropane triacrylate (TMPTA). Applied as a hard coat on top of a polyethylene terephthalate (PET) film, this nanocomposite has a short UV‐cure time and the cured coat has an enhanced thermal decomposition temperature (Td), 89–90% transparency, increased hardness up to 3H, better adhesion up to 4B, and a flat surface with a root mean square roughness of 2–4 nm. The preparation as well as the characterization of the constituting species and the final hybrid are described in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3985–3993, 2007

Seed Dispersal by Kerama Deer (Cervus nippon keramae) on Aka Island, the Ryukyu Archipelago, Japan1

ABSTRACTEndozoochorous seed dispersal by kerama deer (Cervus nippon keramae) was investigated at four sites on Aka Island, the Ryukyu Archipelago, Japan. Kerama deer feces contained seeds of 35 plant species. Most of the germinated seeds were small (1.3 ± 0.18 mm) and had a hard coat, comparable to the germinated seeds in several other studies of endozoochorous seed dispersal by herbivores. Both the numbers and species compositions of seeds differed among the four sites, reflecting differences in the food available to kerama deer among habitats. Although many graminoid seeds were found in the two open habitats (Sites A and B) and in the adjoining forest habitat (Site C), woody plant seeds dispersed endozoochorously by birds and mammals were dominant in the forest (Site D), away from the marsh. Although a majority of the graminoid species was growing in open habitats such as the marsh and open fields, few were growing in the forest. Therefore, the kerama deer spread many open‐habitat graminoid seeds to the open and forest habitats. If a high density of kerama deer persists for a long time and gaps in forests are created by browsing kerama deer or by other means, graminoid species may spread substantially on Aka Island. Therefore, it is possible that seed dispersal by forest deer contributes to the expansion of grasslands.

P-57: A Transparent Plastic Film having Excellent Optical Properties and High Heat Resistance for Flexible Display Substrates

We have developed a new high performance plastic substrate for flexible displays. The plastic substrate has a multi-layered structure composed of a newly developed base film, hard coat layers and gas barrier layers. The plastic substrate has a unique balance of excellent optical properties, high heat resistance over 200 °C, and practical mechanical strength.

Hard coat aluminum anodizing: The low-down on how anodizers can get their feet wet and enter the lucrative hard coat market

Hard coat aluminum anodizing: The low-down on how anodizers can get their feet wet and enter the lucrative hard coat market

複合硬質膜被覆ダイスの耐摩耗性

Wear resistance of duplex hard-coated die for aluminum extrusion are investigated. Nitrided layer of duplex hard-coat was prepared by gas nitriding, plasma ionic nitriding or plasma radical nitriding method, and the 3 μm hard coat films, CrN, TiN or TiAlN was by arc ion plating on the nitrided layer. Hardness, friction coefficient, critical load and roughness of duplex hard-coated specimens (SKD61) were observed before and after oxidation at 500°C or 650°C, atmosphere, 5h. Hardness of coated area of die before extrusion and after removal of adhesive aluminum were compared. Hardness of duplex hard-coat and single hard-coat were also compared. In the case of single hard-coated die which critical load was under 30 N, hard-coat in the front bearing area was deteriorated. On the contrary, duplex hard-coat which critical load was over 60 N, was hardly changed after 5 extrusions. Duplex hard-coated dice showed higher wear and oxidation resistance in comparison with dice singly hard-coated because the hardness of nitrided layer was nearly unchanged after heating at atmosphere.

Structural and chemical characterization of functional SiOxCy:H coatings for polymeric lenses

The deposition of suitable hard protective coatings onto organic substrates for ophthalmic applications faces several challenges, such as proper surface preparation to ensure the adhesion to the rigid substrate and a delicate balance between hardness and flexibility. In this work it is shown that SiOxCy:H-based protective coatings grown by plasma enhanced chemical vapor deposition (PECVD) from mixtures of hexamethyldisiloxane and oxygen, can be used as protective buffer coatings between the soft and easily scratchable substrate and the antireflection stack that might be applied on top of it. These coatings must show absence of optical absorption and require index matching with the substrate. To meet these conditions, a three-phase multifunctional coating PECVD deposition method has been developed, in which a progressive decrease towards the surface in the carbon content of the SiOxCy:H hard coat has been implemented. Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy characterization of the individual layers that compose the multilayer functional structure has been performed. The comparison of the results obtained from each spectroscopy shows the complementarity of these techniques and allows optimizing the protective coating performance from the optical and mechanical points of view.

A New Hard Coat on Cover Layer for Cartridge-Free Blu-ray Disc

A new UV-curable hard coat resin with an excellent antifouling property has been developed. A 3-µm-thick hard coat layer was stacked onto a 97-µm-thick cover layer by spin coating. The characteristics of the hard coat layer, such as pencil hardness, microscratch resistance, adhesion, water contact angle and jitter, have been investigated.

硬質膜被覆ダイスの耐摩耗性と耐酸化性

Resistance of wear and oxidation of hard-coated die for aluminum extrusion is investigated. Nitrided layer was prepared by radical nitriding method, and the 3 μm hard coat films, CrN, TiN, TiAlN and TiAlCrN, were prepared by arc ion plating. Hardness, friction coefficient, critical load and roughness (Ra) of hard-coated specimens (SKD61) were observed before and after oxidation at atmosphere, 500°C-5 h. Roughness (Ra) of coated area of die before extrusion and after removal of adhesive aluminum were compared. Surface composition of coated area after 5 extrusions were analized by ESCA. In the case of nitrided die, whole coated area was oxidized, scraches (depth: 2 mm, width: 20 μm) had occurred in the direction of extrusion and roughness (Ra) was increased after 5 extrusions. On the contrary, the roughness of the coated area with TiAlN films hardly changed after 5 extrusions. TiAlN coated die showed higher durability in comparison with dies coated with nitrided, because of the higher oxidation resistance of TiAlN.

High-Performance Hard Coat for Cartridge-Free Blu-ray Disc

A practical way of realizing cartridge-free Blu-ray disc using nanocomposite UV-curable resin as a hard coat on a laser incident surface of the disc is described. The hard coat is a composite material of UV-curable acrylic resin and nanoparticles of silica. A lubricant that exhibits oil repellency as well as low friction coefficient was added to the hard coat in order to facilitate the removal of fingerprints. It effectively prevents abrasions, scratches and problems of fingerprints on the disc surface. Abrasion and scratch resistances, and ease of fingerprint removal were evaluated and compared with those of a polycarbonate surface and a conventional UV-curable hard coat.

Germination in Prosopis ferox seeds: effects of mechanical, chemical and biological scarificators

Since Prosopis ferox seeds have a hard coat, scarification is needed in order to liberate seeds from their physical dormancy. We analysed the effect of mechanical and chemical scarification agents, and assessed whether the passage through goat and donkey digestive tracts is a scarifying mechanism. We found that the best germination rates are obtained with mechanical treatment, and that the biological treatments had very low germination rates. With subsequent mechanical scarification, seeds from the biological treatments that did not germinate had high germination rates, showing that the seeds are viable but still dormant. This confirm that the passage through digestive animal tracts does not brake physical dormancy, but act as a mechanism of seed liberation from their indehiscent fruit.