Packaging & Consumer goods

The degree of crystallinity and the speed of crystallization determine many of the aesthetic properties of a plastic article made from semi-crystalline polymers.
Organic pigments are known to influence these parameters during the cooling phase of plastic processing, particularly in HDPE injection moulding, but also in polypropylene. This can result in reduced mechanical stability, impact on dimensional stability, warping, and/or shrinkage.
Typical applications where this effect becomes important are containers, crates and caps and closures.
BASF has developed, based on innovative technology, a series of organic pigments which have no or only very little influence on the dimensional and mechanical stability during HDPE processing, and also offers a nucleating agent foor reducing the warpage of PP during injection molding.

Light energy from natural sources (sunlight) and artificial light can cause photochemical deterioration and can provoke color fading or darkening on packaging articles when exposed, even behind a shop-window.
To measure the indoor resistance of packaging materials it is more appropriate to determine the light resistance via real exposure or accelerated testing.
BASF has many years of experience in testing and recommending light-fast and weather resistant systems for indoor and outdoor use.

Plastic packaging such as beverage bottle crates commonly require UV protection by light stabilization and the use of weather resistant pigments.
Exposure to sunlight and other weather conditions can have adverse effects on the useful life of plastic products and can initiate chemical reactions in polymers, which result in discoloration, the breakdown of chemical bonds and loss of chemical and physical properties.
Appropriate pigment and polymer additive selection is necessary to ensure long-term performance in outdoor applications.
The light stabilization system has to be considered together with the pigment formulation, the determinant failure criteria like area of exposure, the expected life time of the article and maintaining brand identity/brand color.

The articles made out of polymers (polyolefins and rubber) very often contain catalyst residues or polymer degradation products that could cause premature aging. These anions have to be neutralized by acid scavengers.

Polypropylene and Polyethylene are predominantly produced using transition metal halogenides as catalysts, which are supported on inorganic carriers, including metal chlorides. During processing halogenic acids are formed due to the influence of heat and shear, which have to be scavenged to prevent polymer degradation or corrosion of equipment.

Usually, acid scavengers are added in combination with antioxidants and other additives via additive blends. Customer specific blends from BASF, the additive incorporation specialists within BASF, is the industry leader in the development, production and supply of additive blend packages.

Polypropylene is a semi-crystalline polymer as many other polymers are, it comprises amorphous and crystalline regions.

When polypropylene crystallizes from the melt, the onset of the phase transformation is the formation of small nuclei. Once this primary nucleation has occurred, the crystal can grow and form spherical macrostructures called spherulites.

The use of nucleating agents leads to higher nucleus density allowing for the formation of a larger number of spherulites during the cooling of the melt, whereas in non-nucleated Polypropylene the spherulites are typically less numerous and are smaller.

Nucleating agents increase several physical and mechanical properties of polypropylene such as stiffness, impact properties, hardness, heat distortion temperature, etc. The improvement of mechanical properties generally enables downgauging, thinwalling and weight reduction of the finished parts. The overall rate of crystallization of polypropylene increases when using nucleators. A higher crystallization speed ensures a faster solidification of the molten polymer upon cooling. This leads to a reduction of cycle-time in molding processes and generally to increased output as well.

Polymers are subjected to oxidation at every stage in their life cycle – during manufacture and processing as well as during storage and end use.

Polymer Degradation through oxidation can change the aesthetic appearance and can destroy functional properties.

BASF offers tailored solutions of Thermo, Processing, and Light Stabilizers that prevent polymer degradation initiated by heat, UV light, mechanical stress, catalyst residues or through reaction with other impurities.

BASF plastic additives help customers meet the most stringent demands of today’s packaging requirements, from technical and esthetic, to disposal and recycling.

In the packaging industry where a great number of products compete for consumer attention, packaging solutions must have strong and also exclusive impact.

Therefore, besides its basic functions, plastic packaging invites the consumer to buy. Grabbing attention, differentiation, safety, aesthetics, corporate identity, advertising and “shelf appeal” are some of the many reasons that color is added to all kinds of plastic packaging applications like crates, containers, caps, bottles and films.

While it is true that virtually any desired color can be achieved using combinations of specific colorants, coloration of polymers typically requires consideration of many other characteristics at the same time.

Successful coloration of plastic packaging requires extensive knowledge of the behavior of the many choices available.

The electrical properties of plastic packaging as well as the rough handling that packages can receive during processing and transport, lead to high electrostatic charges on the packaging surface. The accumulation of the electrostatic charges causes dust build-up on the packaging during their storage and display on the shelves.

The use of an antistatic agent reduces the build up of high electrostatic surface charges, reduces dust contamination and helps to preserve the original appearance of the package.

The addition of effect pigments such as pearlescents to colorants is widely used in the creation of interesting special effects and “flip-flops” in the plastic packaging industry. Especially in cosmetic and body care packaging, these effects are used to support a message of freshness, cleanliness, power, sensuality and warmth. In plastic applications like bottles and small containers, they allow product differentiation and new shelf appeal to attract the consumer.
Pearlescent pigments are also used for laser marking in applications like bottles, caps or lids in the food packaging and home care industry.
Special Effect Pigments develop their full potential in transparent and translucent polymers in combination with very transparent color pigments or polymer soluble colorants. Small amounts of absorbing pigments such as carbon black also are used to enhance the color effect.

Clarity and transparency support a message of freshness and cleanliness and is also a powerful design tool for any plastic packaging to differentiate in all kind of consumer markets.

To cover the growing demand in transparency and clarity applications, BASF has developed a range of colorants and additives.

The incorporation of clarifiers in polypropylene, especially in random copolymers, strongly improves the optical properties, clarity and transparency, and thereby helps to expand its use for new applications, such as containers / bottles for cosmetics and for preserved or fresh food.