Bath, Body, and Hair Care Packaging: Taking Green Plastics to the Next Level
Clariant offers opaque colors and special effects for bottles containing up to 100%-PCR HDPE resin.
What to know about green resins, colorants, and additives.
By Marie Redding, Senior EditorWhen it comes to package strength or custom coloring, green packaging often presents challenges. In turn, for postconsumer recycled (PCR) or bio-based plastic resins used for personal care packages such as bottles, suppliers have developed some problem-solving additives.
A plastic resin usually takes on new properties when an additive is used. Colorants and additives can be supplied separately, or both can be compounded together in a single masterbatch. They are usually added when resin pellets are being melted down, before blow molding or injection molding.
Making PCR and PLA Stronger
Increasing levels of recycled materials in plastic packaging is a goal for many personal care companies right now, but experts say that it’s important to maintain resin durability as recycled content increases. “It’s crucial to know if—and by how much—a bottle’s strength is being compromised as recycled content is increased,” says Pete Prusak, head of packaging, North America, Clariant Masterbatches (McHenry, IL). “Most recycled plastics don’t have the same properties as the original virgin compound. PET is notorious in this regard,” he adds.
Prusak explains that when PET is reprocessed, its polymer chains become damaged. Clariant markets an additive to solve this issue. “Our product, CESA-extend, will rebuild and extend the polymer chains that become broken when PET is reprocessed, restoring most of its performance properties,” says Prusak. “By relinking the broken chains, this additive improves the melt strength of reclaimed PET so that it behaves more like virgin material and can be used in many of the same applications.”
CESA-extend can also be used with the biopolymer polylactic acid (PLA). “Interestingly, virgin PLA also has melt-strength issues similar to those of reclaimed PET,” Prusak says.
David Stonecipher, director of marketing, North America color and additive concentrates for PolyOne (Cleveland), agrees that PLA has strength issues. “Biopolymers such as PLA are not perfect in terms of function. Additives can help them perform better.”
One problem with PLA is that it has poor impact resistance. “It may shatter or crack easily,” Stonecipher says. PolyOne offers its OnCap Bio Impact T additive, which improves the impact resistance of PLA, making it easier to work with during production.
Coloring Recycled PET
Making sure that a colorant is compatible with PCR resin can be another challenge. For instance, sometimes certain colors aren’t possible when using PCR PET. This is when additives might be useful.
“PCR has background hues that you need to mask. These hues need to be compensated for in the color-matching process,” Stonecipher says. Even when the material comes from clear soda and water bottles and is considered to be a high-grade source of PCR, the resin that is reground still won’t be clear. “Also, during processing, the polymer degrades and yellows as it heats up. Antioxidants slow the degradation process, allowing processors to use higher levels of PCR,” Stonecipher explains.
Opaque colors for PCR are always a safer bet. “If you are making an opaque bottle, you can get away with using higher levels of PCR and can more easily mask the background interferences and hit your final color target,” says Stonecipher.
Neal’s Yard Remedies switched all of its hair care and shower care products from glass to 100%-PCR PET bottles.
Deep blue, which is the signature shade for Neal’s Yard Remedies, was perfect for the brand’s 100%-PCR PET bottles. The brand recently switched all of its hair care and shower products from cobalt-blue glass bottles to the new plastic bottles supplied by M&H Plastics (Winchester, VA).
“We were able to achieve the iconic blue color that is core to our branding,” says Jo Everett, packaging technologist and new-product development project manager for Neal’s Yard. Everett is also happy with the improved impact resistance and weight reduction that plastic is providing.
BlueEdge Formula XPET is a PET brightener from Ampacet that counteracts the yellowish-brown hue of PCR resin.
In case dark opaque colors aren’t right for your brand, a specially developed additive will help PCR PET look clearer. Ampacet Corp. (Tarrytown, NY) markets an additive called BlueEdge Formula XPET, which counteracts the yellowing of PCR PET by bringing the color back to a blue shade. That creates a clearer-looking bottle—even for bottles made from 100%-PCR PET, according to the supplier.
“Since BlueEdge is not a pigment, it won’t affect the recycling stream,” says Doug Brownfield, strategic business manager, Ampacet. “At higher loadings, it will create an attractive blue hue around the edges of a container, similar to the effect of plate glass.”
Bath and body brand Lush is using 100%-PCR PET bottles molded by Alpha Packaging. Compared with virgin PET, the “clear” recycled PET tends to have a slightly gray or yellow tint if a clarifying additive is not used. This can be especially apparent in areas such as the neck of the bottle, where the plastic is much thicker. However, Alpha says that many brands don’t mind this slight discoloration, which is somewhat camouflaged by the product and label.
Sometimes achieving perfect clarity is not always the goal, and a slight discoloration will be acceptable by a brand. Lush Cosmetics has bath and body products in clear PET bottles made from 100%-PCR PET and does not use a clarifying additive in the resin.
“The bottles aren’t perfectly clear,” says Marny Bielefeldt, marketing manager, Alpha Packaging (St. Louis), which supplies the packaging to Lush. “Many of our customers don’t mind a slight discoloration or yellowish hue because it makes it more obvious to the consumer that the bottle is recycled plastic.”
Coloring Bio-Based Resins
If you’re opting for a compostable bio-based resin such as PLA, then you may want to think about choosing a biodegradable colorant. Although conventional colorants and additives can be used with compostable resins, traditionally these colorants and additives are synthetic and made from fossil fuels.
“If a bottle made from a starch-based resin is composted, the polymers themselves may break down to their natural components, but synthetic colorants and additives won’t. While this is a relatively minor issue now, it may become more acute as consumption increases,” says Clariant Masterbatches’ Prusak.
Clariant offers all-natural color and additive masterbatches that are made from sustainable resources such as plants. RENOL-natur colorants include shades of red, orange, yellow, and green. (Blue is still in development.) Orange curcuma comes from the root of the spice plant turmeric; yellow urucum is found in flowers that grow in tropical regions such as Brazil; the greens come from chlorophyll and other plant sources; and the natural carmine red colorants are derived from the cochineal insect. These colors can also be combined to create additional shades and tones.
“RENOL-natur colors are very earthy and organic-looking, some with excellent clarity,” says Prusak, “so they’re perfect for brand marketers that want to distinguish sustainable packaging from similar products made with conventional polymers.” One thing to remember, however, is that these colors might not contain certain physical properties expected from traditional pigments, such as lightfastness (the degree to which dyes resist fading when exposed to light).
Based on sustainable raw materials, PolyOne’s OnColor Bio colorants offer a wide range of transparent and opaque colors and special effects for biopolymers such as PLA, while meeting global industry composting standards.
PolyOne also offers a line of colorants for biopolymers such as PLA, called OnColor Bio, in a wide range of effects, from tints and opaque colors to various special effects. PolyOne’s Stonecipher describes a few of the challenges of coloring PLA. “You have to adhere to certain limitations because you don’t want to lose the compostability of the resin, especially with PLA. We are restricted to a certain palette of ingredients that ensure compostability is maintained.”
Enhancing the Look of Recycled PP and HDPE
Colorants and additives are being designed for other types of recycled resins as well. “Polypropylene (PP) is a preferred choice in packaging applications, and can now be considered a replacement for other clear plastics,” says Brian Burkhart, global marketing manager for Milliken Chemical’s (Spartanburg, SC) Millad clarifying agents. “It has a low density, which reduces the amount of material required and reduces the weight of shipments. It is also fully recyclable.” However, PP tends to be hazy, even in its virgin form, and recycled PP tends to be even hazier.
Clarifiers help to make virgin and recycled PP clear. Milliken Chemical’s family of clarifying additives, called Millad, was developed to clarify recycled and virgin PP.
The experts at PolyOne also agree that clarified virgin and recycled PP are being used more now by many companies. “PP is considered a competitor to PET,” says Carl Knight, senior product manager, PolyOne. The supplier’s PPro-Tint colorants are formulated to add transparency to clarified virgin and recycled PP. PPro-Tint contains no dyes and consequently offers better light stability, with no bleeding or migration of color from the plastic, says Knight.
Many personal care marketers also choose packaging made from high-density polyethylene (HDPE). “HDPE is more squeezable, so it’s great for hair gel or shampoo. However, it’s an opaque resin, so it’s not an option for companies that want the clarity of glass,” says Alpha Packaging’s Bielefeldt.
For recycled HDPE, Clariant offers a range of opaque colors and special effects that are designed for single- and multilayer HDPE bottles. “These color and effect systems are part of the Enigma product line and can be used with any level of PCR, up to 100%,” says Prusak.
Recycled PP: Processing Challenges
Sometimes a package developer may shy away from using recycled PP due to processing issues that can arise. “Shrinkage and warpage are common when certain additives and nucleators are present in mixed batches of recycled PP,” says Johnny Netzloff, global marketing manager for Milliken Chemical’s Hyperform nucleating agents. (Nucleators are solid particles, very small in size, that are added to a resin to enable the resin to be processed faster and to improve the quality of parts that are molded.) “Our hypernucleating agent provides a solution to this problem.”
According to Netzloff, Hyperform has the highest peak crystallization temperature (Tc) of any known nucleating agent. When added to recycled PP, it increases and levels the Tc of recycled PP, allowing for faster and more-consistent processing. (Hyperform can also be used with virgin PP.) “The additive also promotes isotropic shrinkage, which is the key to reduced warpage and increased part quality,” says Netzloff. “Using our additives to simplify and expand the use of sustainable, recyclable PP is helping to phase out materials with a heavier environmental footprint,” he says.
Reducing Weight
Another additive that can make a bottle greener is a chemical foaming agent (CFA) to reduce the weight of a resin. Clariant’s Hydrocerol masterbatch can reduce a bottle’s weight by at least 10% without significantly decreasing physical properties or performance, according to the supplier. Reducing weight lowers raw material cost, while lighter loads also enable lower shipping costs.
Activated by the heat of plastics processing, CFAs create a cellular structure of a foam in the polymer, according to the supplier. “By replacing some of the resin volume with microscopic bubbles, the amount of material required to make a structure, such as a bottle, can be reduced by up to 10% with essentially no loss of mechanical properties,” says Clariant’s Prusak. “The presence of Hydrocerol in the polymer also reduces the temperature at which the resin must be processed, and can reduce molding cycle times, cutting energy consumption.”
CFAs also have another use—creating a number of different visual effects. “Because the foam increases light refraction, the appearance of the plastic may change. It has been used in combination with color to create textured looks ranging from translucent etched glass to frosting and soft leather,” says Prusak.
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