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The basic design for
recyclability guideline to consider when making material choices
for any attachment to the bottle is to consider their general
compatibility with the base resin (homopolymer HDPE) or the
removal efficiency in conventional water-based separation
systems that separate plastics by density. These attachments
may include closures, closure liners, base cups, inserts,
labels, pour spouts, handles, sleeves, safety seals, coatings
and layers. HDPE has a density less than 1.0 and will float
in these systems. For efficient separation and removal in
conventional sink/float separation systems, attachments should
be made from materials with a density greater than 1.0 or
be otherwise compatible with HDPE in the reclamation process.
Materials with a density greater than 1.0 will sink in these
systems and can be easily separated from the HDPE. (Density
range of key plastic materials.)
Plastic closures made from HDPE, LDPE or
PP are preferred to all others. Closure systems that contain
no liners and leave no residual rings or attachments when removed
from the bottle are also preferred. For these reasons, ‘snap-on’
caps are preferred to ‘screw-on’ caps. The use of
metal closures is undesirable and should be avoided as they
are more difficult and more costly to remove in conventional
reclamation systems compared to the preferred closure systems
(HDPE, LDPE or PP).
If tamper-resistance is required in specific
product applications, it should be an integral design feature
of the bottle. The use of tamper-resistant or tamper-evident
sleeves or seals is discouraged as they can act as contaminants
if they do not completely detach from the bottle, or are not
easily removed in conventional separation systems. If sleeves
or safety seals are used, they should be designed to completely
detach from the bottle. Shrink sleeves are preferred when sleeves
are necessary. The use of PVC sleeves or safety seals is undesirable
and should be avoided.
Unpigmented, homopolymer HDPE used for milk
and water bottles has the highest value and the widest variety
of end-use applications. Its lack of pigmentation makes it easy
and economical to sort and separate from other plastic bottles.
The use of pigments in homopolymer HDPE bottles is undesirable
and should be avoided.
PP, OPP, HDPE, MDPE, LDPE, LLDPE or PS label
stock is preferred to all other label materials. The preferred
label systems are shrink sleeve labels that require no adhesive,
or those that incorporate the label directly on the closure.
Paper labels are undesirable and should be avoided as they can
increase contamination in the HDPE due to fiber and adhesive
carry-over through the reclamation process. Similarly, metallized
labels increase contamination and separation costs and should
be avoided. The use of PVC labels is undesirable and should
be avoided.
Inks must be chosen that do not bleed color
when agitated in water. Label inks that bleed can discolor the
HDPE homopolymer regrind during the reclamation process, diminishing
or eliminating its value for recycling. The use of inks that
bleed should be scrupulously avoided. (The APR has developed
a testing protocol to assist label manufacturers in evaluating
whether a label ink will bleed in conventional HDPE reclamation
systems.) Label adhesives should be water-soluble or dispersible
at temperatures between 140°F and 180°F in order to
be removed in conventional washing and separation systems. If
adhesives are not removed efficiently, they may disperse on
the HDPE regrind and embed unwanted contaminants. The use of
other adhesive types is discouraged and should be avoided. (The
APR has developed a testing protocol for adhesive manufacturers
to evaluate the impact of adhesive products in conventional
reclamation systems.) Adhesive usage and surface area covered
should be minimized to the greatest extent possible to maximize
HDPE yield and avoid contamination.
Presently, all direct printing other than
date coding, either for product labeling or decoration, contaminates
recycled HDPE homopolymer in conventional reclamation systems.
The inks used in direct printing may bleed ink or otherwise
discolor the HDPE during processing, or introduce incompatible
contaminants. In either case, the value of the HDPE is diminished
or eliminated for recycling.
While unpigmented, homopolymer HDPE bottles
generally do not use a multi-layer construction, it is possible
that future bottle designs might require the use of layers for
specific product applications. The use of layers made from materials
other than unpigmented, homopolymer HDPE is undesirable and
should be avoided, unless they are compatible with or easily
separable from HDPE in conventional recycling systems. If layers
must be used, their content should be minimized to the greatest
extent possible to maximize HDPE yield and reduce potential
contamination and separation costs. (The APR’s Champions
for Change Cooperative Testing Program invites consumer product
manufacturers and plastic bottle and bottle component manufacturers
to work with APR member companies to determine whether new modifications
to a regularly recycled plastic bottle will impact conventional
recycling systems prior to introducing the modification.)
The use of any other attachments
is discouraged, as they reduce base resin yield and increase
separation costs. Other attachments may include handles, inserts,
and pour spouts, in addition to others that might be developed.
If attachments are added to a bottle, they should be made from
1) materials with a density greater than 1.0 that will easily
separate from HDPE in conventional separation systems or, 2)
compatible materials such as PP, LDPE or preferably, unpigmented,
homopolymer HDPE. The use of PP or LDPE attachments, if necessary,
should be limited to less than 5 percent of the total bottle
weight. Higher percentages can contaminate the HDPE for many
recycling applications, as these materials are difficult to
separate from HDPE in conventional systems. If adhesives are
used to affix attachments, they should be water-soluble or dispersible
at temperatures between 140°F and 180°F in order to
be removed in conventional washing and separation systems.
If adhesives are not removed efficiently, they
may disperse on the HDPE regrind and embed unwanted contaminants.
The use of other adhesive types is discouraged and should
be avoided. (The APR has developed a testing protocol for
adhesive manufacturers to evaluate the impact of adhesive
products in conventional reclamation systems.) Adhesive usage
and surface area covered should be minimized to the greatest
extent possible to maximize HDPE yield and avoid contamination.
The use of post-consumer HDPE in bottles
is encouraged, whenever possible. |
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