Spectrophotometers are quality control devices that provide numerical values for color. In the plastic manufacturing industry, blow-cut, multilayer, biaxially oriented film extrusion lines move quickly and only have to stop to change jobs. To ensure quality, many plastic manufacturers extract a film sample to be measured in the laboratory, but when a problem of color, turbidity or transparency is identified, most of the print run has already been wasted. An early warning system can help plastic manufacturers keep color, brightness, transparency and haze in harmony so that the line can keep moving. The main challenge when it comes to controlling color is how to transmit an accurate measurement correlation at different stages of the supply chain.
It is similar to building a garage with just a cane to measure the dimensions of the garage. Unless you and your builder have an accurate measurement of the stick in question, your specification of a distance of “1½ sticks” wouldn't translate to the builder. Transparent plastic sheets allow sunlight to enter, but visibility will not be as clear or more “cloudy”.Plastic film manufacturers have developed disease control films that absorb UV radiation at wavelengths of 340 to 390 nm. These films have been found to reduce the population of insects such as whiteflies, mining thrips and aphids.
The material can also control the spread of certain diseases, such as botrytis. Luminescent plastics are characterized by modifying the quality of light in the spectrum, basically in the violet and visible part. Most greenhouse polyethylene films are manufactured as a co-extrusion of three or more layers with different polymers and additives. Construction officials often question a producer applying for a building permit about the flammability of plastic film. To avoid catastrophic scenarios, it is vital to understand what conditions plants need and how the color of plastic films influences crop yields. For example, if the greenhouse is used to germinate seeds or young plants that will then be moved outside, it is recommended to use a colorless plastic film that allows more direct sunlight to enter and increase the temperature and boost the germination process.
An online solution from X-Rite can help manufacturers of plastic films and sheets to ensure color harmony, from raw material inspection and color matching in the laboratory to production quality control and final inspection. When it comes to covered crops, it's best to ensure that everything is under control with plastic films. The use of colorless plastic films in greenhouses has many advantages, such as emitting direct light to the structure to heat the soil while providing an adequate temperature for seeds to sprout. Plastic manufacturers have discovered that mineral-based additives, such as ethyl vinyl acetate (EVA), calcined kaolin clay, or synthetic aluminum silicate, can reduce radiation loss. However, a disadvantage of using colorless plastic films in greenhouses compared to more opaque films is that direct incoming light creates hot spots while there are other areas of greenhouse cultivation with a lower or colder temperature where plants remain in the shade. Juan Antonio García, product director of Greenhouse Plastics of the Armando Alvarez Group in Spain points out that when it comes to photoselective plastic, color can directly affect plant processes and therefore fruits and their production, sprouting, follicular development, flowering, fruit color, disease reduction etc. The X-Rite online plastic color measurement and control system includes a non-contact spectrophotometer, a customized transverse beam to reach predefined positions on the plastic belt and quality control software to monitor color throughout the race.
