Multilayer polymeric film

Details Multilayer polymeric film Multilayer polymeric film

1999-05-27

2004-01-27

Tarazano, D. Lawrence (Department: 1773)

Stock material or miscellaneous articles

Composite

Of silicon containing

C428S516000, C264S173150

Reexamination Certificate

active

06682822

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a multilayer polymeric film. More particularly, the present invention relates to an improved multilayer polymeric film in which the coefficient of friction (COF) and the release character of the film are less susceptible to, or more resistant to, handling or mishandling during further treatment of the film by various users (e.g., converters). Additionally, the present invention relates to cold seal release films comprising such improved multilayer polymeric films.
BACKGROUND OF THE INVENTION
Multilayer polymeric films are used to manufacture cold seal release films that may be reverse-printed and laminated to a variety of substrates. In certain applications, it may be desirable to treat (e.g., by corona or flame treatment) a surface (e.g., the print face) of the multilayer polymeric film. During the treatment, however, the opposite surface (i.e., the release face) may be treated in addition to, or instead of, the intended surface through so-called “backside treatment” or through operator error. Such handling or mishandling may detrimentally affect the COF and release character of the film.
Thus, it would be desirable to provide a multilayer polymeric film that is less susceptible to, or more resilient to, the above-described “backside treatment” or mishandling by the operator. That is, it would be desirable to provide a multilayer layer polymeric film that possesses a stable COF and good release character in spite of such treatment or mishandling.
The present invention provides an effective solution to the above-described problem.
U.S. Pat. No. 4,692,379 to Keung, et al. discloses a film having an upper heat sealable layer formed from an ethylene-propylene-containing copolymer or terpolymer and an antiblocking agent and a lower heat sealable layer formed from an ethylene-propylene-containing copolymer or terpolymer and antiblocking agent and a quantity of silicone oil such that the coefficient of friction-reducing amount of the silicone oil will be present on an exposed surface of the upper heat sealable layer following mutual contact of the upper and lower surfaces. The silicone oil additive is described as having a viscosity of from about 350 to about 100,000 centistokes, with about 10,000 to about 30,000 centistokes being preferred. An advantage of the invention as described in the '379 patent is that the silicone is present on the exposed surface of the lower layer in discrete microglobules which, to some extent, transfer to the upper surface upon contact. The silicone on the surfaces of the film facilitates machinability.
U.S. Pat. No. 4,734,317 to Bothe, et al. discloses a biaxially oriented multilayer polyolefin film which comprises a polypropylene base layer, a first polyolefin sealing layer positioned on one side of the base layer, and containing from about 0.5% to 3% by weight of incorporated polydialkylsiloxane, the first sealing layer not being subject to corona treatment, and a second polyolefin sealing layer positioned on the other side of the base layer and having a coating of the polydialkylsiloxane on its outer surface, the second sealing layer being subject to corona treatment, wherein the polydialkylsiloxane coating is formed by contact of the first and second layers.
U.S. Pat. No. 4,925,728 to Crass, et al. discloses a biaxially stretched multilayer film comprising a base layer essentially comprising polypropylene and at least one top layer, wherein the top layer essentially comprises (a) 98.5% to 99.6% by weight of a propylene homopolymer and (b) 0.4% to 1.5% by weight of a polydiorganosiloxane, relative to the top layer.
U.S. Pat. No. 5,482,780 to Wilkie, et al. discloses a polypropylene film with cold seal release and cold seal receptive surfaces, wherein a predominantly isotactic polypropylene homopolymer core has on one side thereof an ethylene-propylene random copolymer having a physically modified surface for reception of a cold seal cohesive composition and on the other side of the core there is a blend of an ethylene-butylene copolymer and an ethylene-propylene random copolymer containing a non-migratory slip agent. The preferred non-migratory slip agent is described as being a crosslinked silicone having a particle size of about 1 to 4.5 microns, such as that identified by TOSPEARL of Toshiba Company.
U.S. Pat. No. 5,489,473 to Wilkie discloses biaxially oriented polypropylene cold seal packaging films comprising at least one cold seal release layer and a cold seal receptive layer. The use of crosslinked silicone in the cold seal release skin layer is also disclosed.
U.S. Pat. No. 5,792,549 to Wilkie discloses a coextruded biaxially oriented polyolefin packaging film comprising a cold seal release layer, a core layer, and a cold seal receptive skin layer. The use of crosslinked silicone having a particle size of about 1 to about 4.5 microns such as that identified by TOSPEARL of Toshiba Company is also disclosed.
U.S. Pat. No. 5,798,174 to Wilkie discloses cold sealable films for heat sensitive packaging operations comprising, in order, a cold seal cohesive layer, a core layer, and a cold seal release layer comprising a mixture of about 1 to about 80% by weight butene-propylene copolymer and about 99 to 20% by weight butylene-ethylene copolymer.
U.S. Pat. No. 5,840,419 to Alder discloses a multilayer polyolefin film comprising a core layer of a propylene polymer and an outer polyolefin layer on the core layer, the outer polyolefin layer including a coefficient reducing amount of a particulate, partially crosslinked polysiloxane, which are preferably in the form of elastomeric particles including polysiloxane in the form of silicone oil. The patent states that the silicone oil is released when the particles are “subjected to mechanical stress.”
SUMMARY OF THE INVENTION
The present invention is directed to a multilayer polymeric film comprising:
(a) a core layer comprising a thermoplastic polymer and optionally an antistatic agent, the core layer having a first side and a second side;
(b) a functional layer which is printable or sealable or treatable for printing or sealing on the first side of the core layer; and
(c) an additional layer on the second side of the core layer comprising a polypropylene homopolymer, a solid antiblock, and silicone oil.
In another embodiment, the present invention relates to a cold seal release film comprising:
(a) a core layer comprising a thermoplastic polymer and optionally an antistatic agent, the core layer having a first side and a second side;
(b) a functional layer which is printable or sealable or treatable for printing or sealing on the first side of the core layer; and
(c) an additional layer on the second side of the core layer comprising a polypropylene homopolymer, a solid antiblock, and silicone oil.
In yet another embodiment, the present invention provides a process for producing a multilayer polymeric film comprising:
(a) coextruding a core layer comprising a thermoplastic polymer and optionally an antistatic agent, a functional layer which is printable or sealable or treatable for printing or sealing, and an additional layer comprising a polypropylene homopolymer, a solid antiblock, and silicone oil;
(b) cooling the coextruded film; and
(c) optionally orienting the film in at least the machine and/or transverse directions.
It has been found that the present invention provides a multilayer polymeric film which exhibits a stable COF and good release character, even when the film is subjected to treatment or mishandling known to detrimentally affect COF and release character.
DETAILED DESCRIPTION OF THE INVENTION
The core layer comprises a thermoplastic polymer which has properties suitable for extrusion or coextrusion followed by biaxial orientation in the machine and transverse directions under elevated temperature so as to form a multi-layer film. Although the preferred thermoplastic polymer of the core layer is a polypropylene homopolymer, other polymers may be used. These polymers include any polymer made from a 2 to 4 carbon atom olefin,

Affiliated with

Also associated with

Rating

Multilayer polymeric film does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Multilayer polymeric film, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayer polymeric film will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3264521