Additives scratch resistance

BYK-Chemie has introduced scratch-resistant additives consisting of nanosized aliunina in a water-based dispersion. Early applications are envisaged to be in coatings for vinyl flooring. 

Significant work in the literature has been done investigating the influence of different rubbers or elastomers to achieve both high scratch resistance and good low temperature impact strengthAdditionally, the use of slip agents as scratch resistance additives has also come into common practice. In this study the effect of the PP resin on the physical and mechanical performance of molded-in-color TPO was examined. Specifically, the influence of the PP resin type on the scratch resistance was the center of focus. Two PP resins were examined, a PP impact copolymer and a high crystalline PP homopolymer. 

Scratch resistance depends on the hardness of the added particles. The problem of a lack of this property can be addressed by adding chemically identical particles of different crystal modification and Mohs hardness. The preferred additives are silica, alumina, layered silicates such as kaolin, titania, barium sulfate and calcium carbonate. The latter is only suitable for the DMT process owing to side reaction caused by acidity during the terephthalic acid (TPA) route. 

Another possibility mentioned above is the addition of nanoscale particles to a liquid matrix system where the nanoscale particles are grown outside of the system. Experiments have been carried out with boehmite in a matrix derived from Si(OR)4/Al(OR)3 and glycidyloxypropyl triethoxy silane (GTPS) [22]. Even the addition of 5 % by volume of y-alumina or boehmite leads to systems which show a remarkably increased scratch-resistance compared to the unfilled material. The optical transparency is not influenced if the particle size of the boehmite is below 20 or 30 nm. In Fig. 21 the scratch resistance by the Vickers diamond test of the unfilled system is compared to the filled system and, as one can see, the scratch resistance is increased remarkably. 

The choice of materials available for long-term drug contact is very limited—borosilicate glass, bromobutyl or chlorobutyl rubber closures, certain inert polymers such as polytetrafluoroethylene (PTFE), tetrafluor-oethylene (TFE), and derivatives thereof, and stainless steels. Since the Code of Federal Regulations mandates that it be possible to inspect the drug product after filling, steel cannot be used as the primary drug container. In addition, polycarbonates, which would be ideal materials from durability, scratch-resistance, and cost perspectives, have very poor moisture vapor and extractables profiles. 

The data obtained clearly demonstrate that the scratch resistance of polyacrylate coating materials can be strongly enhanced by incorporation of methacryloyloxymethylsilanes (the reasons for the low value of gloss retention observed for 3c are not yet fully understood). As an additional benefit, the cured clearcoats revealed an extremely high chemical resistance no change in the films were observed after a 500 h exposure to 30% aq. H2SO4 test or after 100 cycles in the MEK rub test [4]. 

In plastics, the addition of talc improves their heat distortion temperature, dimensional stability, scratch resistance, impact resistance, and reduces the process cycle due to nucleation. Other important properties include high brightness, blocking of infrared in agricultural film, anti-blocking properties, and low absorption of packaged components. 

In spite of the fact that scratch resistance is very important requirement only a limited number of credible studies have been done. This research is very difficult to conduct.Recently, image analysis was employed to overcome some of the technical difficulties associated with the interpretation of observations. In addition to the damage of the scratch itself, the surrounding areas show stress whitening which adds to the perceived damage. The use of plastics in the automotive industry, especially the wide use of polypropylene makes these studies very important in the development of high quality finished products. 

Sanes J, Carrion FJ, Bermudez MD (2010) Effect of the addition of room temperature ionic liquid and ZnO nanoparticles on the wear and scratch resistance of epoxy resin. Wear 268 1295-1302... 

Incorporation of small amounts of polytetrafluoroethylene in the PPS coating formulation provides hard, scratch-resistant release coatings (14). The use of release coatings of this type in food contact service is permitted by Section 121.2621 of the Food Additives Regulations. 

The potential of CVD has begun to bear fruit in many areas. The process ability to rapidly coat non-planar objects in a cost-effective manner has contributed to a rapid rise in the adaptation of the technique. For example, solar cells and layers now are routinely fabricated by CVD approaches. Additionally, synthetic gold coatings (off-stoichiometry TIN) are put down for cosmetic reasons on large volumes of personal jewelry. The scratch-resistant material makes for a tough outer shell at an exceptionally attractive economic cost. 

Use with low-speed spray buffing or high-speed maintenance programs. Maintains a high initial gloss and can be burnished daily or on an intermittent schedule. Very responsive to both electric and propane machines. Wax addition improves scratch resistance. A consistent high level of appearance can be sustained over an extended period. Up to five coats per application... 

For scratch resistance improvement of organic surfaces also nano-composites are of interest. In a composite nano-scale boehmite or y-aluminia particles of about 15 nm diameter have been used as catalysts for epoxy groups linked to hydrolyseable and condensable silanes. Epoxy polymerization preferably takes place around the nanoparticles and additionally =Si-0-Al= bonds are formed between the silanes and the alumina surface [486]. It seems that the nano-particles, only 5% in volume fraction, are flexibly suspended in an inorganic-organic network. Such systems can be produced as transparent coatings and cured at relatively low temperatures of 90 to 120°C to high performance scratch resistant layers. 

Ultra-high molecular weight polyethylene (UHMWPE) can also be considered as sncb an intentional additive, becanse it can be nsed for scratch-resistant coatings, which can... 

As with most photochromic lenses, the performance of plastic photochromic lenses is temperature-dependent. In addition to variable light attenuation, photochromic lenses offer protection against UV light. Photochromic plastics coated onto classical glass lenses provide abrasion/scratch resistance and highly functional antireflectivity. For further details, the reader is referred to a review article [61]. 

Stiffness plus low-temperature impact With their use growing at about 10% per year, TPOs can provide varying levels of impact resistance and varying flexural modulus values and are tailored for particular applications, from the most extreme exterior bumper fascia parts to softer interior components (Chapters 7 and 8). Other additives pair these properties with scratch-resistance (Chapter 17). 

---