THE COMPOSTE MATERIAL FOR KITCHEN SINKS
Sintetika Sinks S L
SINTETIKA’ sinks are made up of composite materials with a thermostable base and mineral charges, everything reinforced with fibreglass. Other components are added on to this compound, such as thermoplastic additives, catalysators, thickeners, and pigments. The way of displaying the composite for its processing and the utilization of components such as granite, bring us to several denominations: SMC delivered in sheets, BMC delivered in blocks with 10% of natural stones, MMC with mineral additions up to 40%, et cetera. The PiMC (Powder in Mould Coating) is a electrostatic powder covering applied over a warm mould before pressed; it polymerise with the SMC base material making a high resistant decorative lay. The transformation is made in a warm mould (130-160ºC) under high pressure (120 BAR); during these hard conditions held along a given time, the material polymerises. This is a non reversible process, which means that after the material has been polymerised, it can not be melted down by high temperatures as opposed to thermoplastic. In order to achieve in some models a peculiar surface finishing and aesthetic, a fine dust paint is applied on to the mould, which polymerises together during the moulding process.
It is what we call Powder in Mould Coating (PiMC). Composite is used in many different sectors like in the car industry where to achieve a reduction of weights and an increase of the structural resistance has become a main goal: fins, carbody elements, ceiling, structural pieces, motor fan, bumper, truck cabins... In the public transportation composite is used for door panels, window frames, inner pillars of trains, trays for heavy luggage, seats... In the electric field is used for making housings for outdoor lights, electric closets, housings for irons, other appliances... In the construction sector composite is used for the outdoor panels of a building, cornices, grids for drains, balconies, decorative details, bathtubs, sinks...
The main difference lies in the use of fibreglass as a reinforcement element. Fibreglass, using the resemblance of the reinforced concrete, is the iron in the concrete. Fibreglass is the element which mechanically joins the rest of components: resinas, mineral loads and additives. The effectiveness of this union provides the product with a greater elasticity, improving its resistance against impacts and thermal shocks. This characteristic is very important when we think all the cold and warm quick changes that a sink suffer everyday. When we break a composite sink it deforms and breaks, meanwhile a acrylic one presents a fragile breakerage.
Therefore an acrylic sink will break apart without previous mechanical deformation. The use of fibre let design lighter pieces so a designer can use its shape as a resistant section. Acrylic sinks need a lot of mass in order to reinforce those angles and sections, that would otherwise risk breaking apart. In this way, a heavier sink does not mean a better quality one but a reinforcement need. In new buildings or installations of any kind, an installer will always be happy to carry around lighter sinks, that are easy to handle. We would like to mention the following characteristics:
1.- Thermal shocks resistance Laboratory tests had shown that the resistance to a thermal shock of an acrylic sink is very much lower than the resistance of a composite one. This is something that has been proved through the problems arisen in the market. The test is made pouring cold water (12ºC +/-2º) during ten minutes and then pouring hot water (90ºC +/-2º) for the period of time, cycle after cycle. After less than 1.000 cycles, a standard acrylic sink easily breaks whilst a composite sink gets over 10.000 cycles without any problem due to its elasticity. Corian sinks hardly resists 500 cycles. This test is based on Project European Norm PrEN 13310.
2.- Mechanical shock resistance An acrylic sink stands the fall of a 500 gr. ball from a 80 cm height. A composite one resists the same impact from a 140 cm height. These impacts are always made over the sink main side. According to ISO179, composite sinks get 78 KJ/m2 and acrylic sinks 6 KJ/m2. 3.- Cleanness and household chemicals resistance According to DIN 53799 (one day opened to air, one week sealed with vaseline) every stain can be easily water cleaned from both kinds of sinks. Only for a few stains of fat kind, an alcohol dissolvent is neccesary to remove them. Both kinds also fulfill the european norm PrEN 13310 with the following foodstuff-simulating substances: methyl, sodium hydroxide, sodium hypo-chloride, ethanol and sodium chloride. When placed against acrylic sinks, the composite sinks always come better off, because of the more hygienic surfaces on which no bacteria and other microorganisms thrive.
4.- Resistance to abrasion Both kinds show similar conditions. In a test based on ASTMD640 made with MG/100 cycles with H18 sandpaper, composites get a value of 72 mg and acrylic sinks 78 mg. Composite models fulfill PrEN13310 where a TABER test is defined with S33 sandpaper and weight of 250 gr resisting 500 cycles.
5.- Hot pan resistance Both kinds resists a pan full of oil (180ºC) placed directly from the fire during 30 minutes. SMC-PiMC have proven a resistance up to 400ºC with no burns or signs left on the surface of the sink.
6.- Hardness and scratch test Composite and acrylic have similar magnitudes, being the acrylic one slightly higher. ROCKWELL M hardness of 100 (acrylic) and 75 (composites) according to ISO2039/2. At scratching, both materials get over the standard european norm PrEN-13310.
7.- Coefficient of linear expansion SMC-PiMC: 2,5x10 – 5ºC-1 Acrylic: 4,5x10 – 5ºC-1
8.- Density Composite: 1,6 gr/cm3 Acrylic: 1,75 gr/cm3. That makes the sink heavier and, therefore, difficulties of manipulation and installation.
9.- Extension till breaking point The extension till breaking point is 2% in both cases. 10.- Cigarette test behaviour According to ANSI Z124-6, both kinds of sinks have the same behaviour.