Polypropylene

The use of unpigmented PP bottles is generally preferred to pigmented bottles as the unpigmented bottles have a greater number of potential applications.

Plastic closures made from HDPE, LDPE, or PP are preferred to all others. Also preferred, are closure systems that contain no liners and leave no residual rings, or other attachments, on the bottle after the closure is removed. The use of closures that are unpigmented or the same color as the bottle is desirable, if practical. The use of PVC for closures or closure liners is undesirable and should be avoided. The use of metal closures is undesirable and should be avoided as they are more difficult and more costly to remove in conventional PP 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, leaving no remains on the bottle. Shrink sleeves are preferred to adhered labels. Shrink sleeves made from PE or PP are preferred. The use of PVC sleeves or safety seals is undesirable and should be avoided. Foil safety seals that leave foil or remnants or attaching adhesive on the PP bottle should be avoided.

PP, OPP, HDPE, MDPE, LDPE, LLDPE, or PS label stock is preferred to all other label materials. Metallized labels increase contamination and separation costs and should be avoided. The use of PVC labels is undesirable and should be avoided. Paper labels are undesirable and should be avoided as they can increase contamination in the PP due to fiber and adhesive carry-over through the reclamation process. Full bottle sleeves should be so designed that automatic sorting equipment can properly identify the resin used to make the bottle.

Inks must be chosen that do not bleed color when agitated in water. Label inks that bleed and can discolor the PP regrind in the reclamation process, diminishing or eliminating its value for recycling. The use of label inks that bleed should be scrupulously avoided. (The APR has developed a testing protocol to assist label manufacturers in evaluating whether label ink will bleed in conventional PP reclamation systems).

The use of “hot melt” adhesives is undesirable and should be avoided unless the adhesive readily separates from the plastic and does not cause problems in the reclaiming process. Label adhesives should be water soluble or dispersible at temperatures between 140 °F to 180 °F in order to be removed in conventional washing and separation systems. If adhesives are not removed efficiently, they may disperse on the PP 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 PP yield and avoid contamination.

Presently, all direct printing other than date coding, either for product labeling or decoration, contaminates recycled PP in conventional reclamation systems. The inks used in direct printing may bleed ink or otherwise discolor the PP during processing, or introduce incompatible contaminants. In either case, the value of the PP for recycling is diminished or eliminated.

Some PP bottle designs require the use of layers for specific product applications. The use of non-PP layers is undesirable and should be avoided, unless they are compatible with or easily separable from PP in conventional recycling systems. Current PP recycling systems can tolerate the use of EVOH layers. 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, 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 nucleated PP is discouraged and should be avoided as nucleation restricts the use /of the postconsumer PP in some applications. Clarified PP is acceptable when bottles are shown to be compatible with end uses for recycled PP.

Other attachments made entirely of PP are preferred, as non-polypropylene attachments reduce base resin yield and increase separation costs. Other attachment may include handles, inserts and pour spouts, in addition to others that might be developed. The use of non-PP attachments should not be adhesively bonded to the bottle and should readily separate from the bottle in conventional PP reclamation systems. If attachments are added to a bottle, they should be made from 1) materials with a density greater than 1.0, with the exception of PVC, which is undesirable and should be avoided, that will easily separate from PP in conventional separation systems or, 2) compatible materials such as pigmented, or preferably unpigmented PP. The use of HDPE or LDPE attachments, if necessary, should be limited to less than 5% of the total bottle weight. Higher percentages can contaminate the PP for many recycling applications, as these materials are difficult to separate from PP in conventional systems. If pour spouts are added to a bottle, they should be designed to leave no product residue and allow for complete removal of product contents when the bottle is emptied. The uses of attachments that contain metallic components are discouraged and should be avoided. If adhesives are used to affix attachments, they should be water soluble or dispersible at 140 °F to 180 °F in order to be removed in conventional washing and separation systems. If adhesives are not removed efficiently, they may disperse on the PP 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 PP yield and avoid contamination.

The use of postconsumer PP in bottles is encouraged, whenever possible.