Resin materials

This section provides a brief description of common plastic container resin materials, their qualities, usages and limitations.

 

High Density Polyethylene (HDPE)

 

HDPE is the most widely used resin for plastic bottles. This material is economical, impact resistant, and provides good moisture barrier properties. HDPE is compatible with a wide range of products including acids and caustics but is not compatible with solvents. It is supplied in FDA approved food grade.
HDPE is naturally translucent and flexible. The addition of colour will make HDPE opaque although not glossy.
HDPE lends itself readily to silk screen decoration. While HDPE provides good protection at below freezing temperatures, it cannot be used with products filled at over 160° F or products requiring a hermetic (vacuum) seal.

 

Low Density Polyethylene (LDPE)

 

LDPE is similar to HDPE in composition. It is less rigid and generally less chemically resistant than HDPE, but is more translucent. LDPE is used primarily for squeeze applications. LDPE is significantly more expensive than HDPE.

 

PET

 

Polyethylene Terephthalate is commonly used for carbonated beverage bottles. PET provides very good alcohol and essential oil barrier properties, generally good chemical resistance (although acetones and ketones will attack PET) and a high degree of impact resistance and tensile strength. The orienting process serves to improve gas and moisture barrier properties and impact strength.
This material does not provide resistance to high temperature applications -- max. temp. 160° F.

 

Polyvinyl Chloride (PVC)

 

PVC is naturally clear, has extremely good resistance to oils, and has very low oxygen transmission. It provides an excellent barrier to most gases and its drop impact resistance is also very good. This material is chemically resistant, but it is vulnerable to solvents.
PVC is an excellent choice for salad oil, mineral oil, and vinegar. It is also commonly used for shampoos and cosmetic products. PVC exhibits poor resistance to high temperatures and will distort at 160° F, making it incompatible with hot filled products.

 

Polypropylene (PP)

 

Polypropylene is used primarily for jars and closures and provides a rigid package with excellent moisture barrier properties.
One major advantage of polypropylene is its stability at high temperatures, up to 200° F. Polypropylene is autoclavable and offers the potential for steam sterilization. The compatibility of PP with high filling temperatures is responsible for its use with hot fill products such as pancake syrup.
PP has excellent chemical resistance, but provides poor impact resistance in cold temperatures.

 

Polystyrene (PS)

 

Styrene offers excellent clarity and stiffness at an economical cost. It is commonly used with dry products including vitamins, petroleum jellies, and spices. Styrene does not provide good barrier properties, and exhibits poor impact resistance.

 

Fluorine Treated HDPE

 

Bottles produced with a mixture of fluorine gas and air, or exposed to fluorine gas in a secondary operation, are similar in appearance to HDPE and have exceptional barrier properties to hydrocarbons and aromatic solvents. Fluorine treated HDPE bottles also resist penetration by oxygen and carbon dioxide.
Fluorine treated bottles are excellent for use with insecticides, photographic chemicals, agricultural chemicals, household cleaners, waxes, paint thinner and gasoline.

 

Comparison of Bottle Polymer Materials

 

Material Clarity O2 CO2 Flexural Modulus x103 Impact Strength Maximum Hot Fill (Fo) Minimum Tolerance  (Brittleness) Co Density g/cc
PEBD P 9,500 42,000 50 G 150o -100o 0.92
PEHD P 4,000 18,000 150