Cap Liner Types
Choosing a liner type and style is one of the most important factors of cap selection. Certain products such as chemicals, consumer products or foods may require specialized liners. Different liner materials may be used for moisture barriers, chemical resistance, consumer safety, or preventing leakage. Depending on the material, cap liners may also influence the cost of your finished product. For more information on types of caps and closures, visit the Selecting Closures info page. As always, be sure to test your product with the liner you choose to be sure they are compatible.
A three-ply liner composed of a low density foam core between two solid layers of low density polyethylene.
Benefits: F217 liners have excellent chemical resistance and a low moisture transmission rate. F217 also has good taste and odor resistance.
An ideal general-purpose liner material, the compressible PE foam creates a stable seal.
Benefits: PE foam has good chemical resistance against acids, alkalis, solvents, alcohols, oils, household cosmetics, and aqueous products.
Disadvantages: It has fair to poor resistance against hydrocarbon solvents.
PS 22 Liners
A pressure sensitive foam liner with one adhesive side that sticks to the container with the pressure used to secure the closure onto the container. When the closure is removed, the pressure sensitive liner remains on the top of the container.
Benefits: PS 22 lined caps are often used for tamper evidence because once the liner has been removed, it cannot be reapplied.
Induction liners have several layers: pulpboard, wax, foil, and a polymer coating. When passed through an induction machine, the heated foil melts the wax and polymer, creating a hermetic seal with the container when solidified.
Tamper Evidence - Once the liner has been removed, it cannot be reapplied to the container.
Hermetic Seal - An induction liner creates an airtight seal to help prevent leakage.
Disadvantages: Induction lined caps must be applied using an induction sealing machine.
Poly Vinyl Liners
A pulp / poly liner consists of a poly-vinyl film adhered to a white pulp paper backing.
Benefits: A good liner for chemical resistance, mild acids, alkalis, solvents, alcohols, oils and aqueous products.
Disadvantages: Not recommended for active hydrocarbons or bleaches.
Polyseal ™ Liners
Made from LDPE plastic, these cone liners provide a wedge-type seal across the top of the container as well as the inside diameter.
Benefits: Commonly used for liquid products, cone liners are stress crack resistant, offer superior torque retention, and have excellent sealing characteristics.
Teflon® PTFE Liners
A variety of liners may have Teflon® facing, such as silicone or PE foam. A Teflon®-faced liner will maintain the base liner's sealing properties while adding superior chemical resistance.
Benefits: Ideal for withstanding volatile solvents, sensitive compounds and corrosive chemicals that would degrade other liner materials.
A polyester film laminated to aluminum foil, bonded to pulp board.
Benefits: Pulp metal foil liners have good barrier properties and good resistance to hydro carbonates, oils, ketones and alcohols.
Disadvantages: Not recommended for acids or alkalis.
A plastic gasket on the inside of a metal closure that creates an airtight seal with the container when properly heated and cooled.
Benefits: Provides tamper evidence and a hermetic seal.
Disadvantages: Must be used with containers that can withstand high heat.