Robton Industries is one of the premiere plastic bag, sheet and tube manufactures in the Philippines. We have been serving several of the biggest companies and businesses in the country for more than 50 years. Robton Industries specializes in blown film PE and PP extrusion and high-resolution color printing for food grade and non-food grade requirements.
Bags are often made of high density polyethylene (HDPE). This plastic is usually milky white or semi-translucent, has superior puncture, low permeability and temperature resistance, and is more rigid and stronger than LDPE / LLDPE but also tears easier and has a propensity to crinkle. Most shopping, grocery and trash bags in the USA are made of this plastic. HDPE is often chosen for its high strength and low cost.
Low density polyethylene or LDPE is another very popular polyolefin. Bags made from this material are either white in color or clear. LDPE is often chosen for consumer packaging where strength is not a requirement like bags for bread, newspapers, frozen food, fresh produce, dry cleaning garments, etc. Bags made from this material are very flexible and easy to stretch, and are clear and glossy. They also have good tear resistance and good moisture barrier properties but only fair gas barrier properties.
Linear low-density polyethylene has similar properties as LDPE and finds uses for similar applications. However, there are some differences which makes LLDPE preferable for different applications. For example, LLDPE is selected for its higher tensile and impact strength and better heat sealability, whereas LDPE is often selected for its higher clarity, ease of processing and higher gloss. Important applications include shopping, frozen food, garbage, news paper, and general food bags.
Polypropylene (PP) is a thermoplastic of high clarity, high gloss, good tensile strength, excellent chemical and heat resistance. It has a higher melting point than PE which makes it suitable for applications that require sterilization at high temperatures. Like PVC it has low gas permeabiltiy, i.e. it is not breathable, and is easy to heat seal. PP is often chosen for food packaging where low permeability, heat sealing and high clarity is advantageous or required like bags for candies, cookies, herbs, nuts and other confectionaries.
OPP stands for Oriented Polypropylene film. It is a widely used material in food packaging, flower wrapping and for labels.
BOPP stands for Biaxially Oriented Polypropylene film and its properties are slightly different to those of OPP film. BOPP excels in its fine clarity, temperature resistance, strength and barrier properties. It is also available in a wide assortment relative to thickness and surface qualities.