Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
1999-12-09
2004-03-09
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C428S516000, C428S520000, C264S173120, C264S173150, C264S173160
Reexamination Certificate
active
06703141
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a matte surface film. More particularly, the present invention relates to a multilayer polyolefin matte surface film including a non-hydrocarbon polymer blended with a polyolefin polymer.
BACKGROUND OF THE INVENTION
Matte surface films have a variety of useful purposes. Primarily, they form a good background for displaying printed or artful images on the film. The images can be printed onto the matte surface film by any conventional plastic printing process.
Mobil Chemical Company film product “70 MLT” is a matte surface biaxially oriented multilayer film. The base layer is oriented polypropylene and the matte surface skin layer comprises a mixture of polyethylenes and an ethylene-propylene-butene-1 terpolymer. The matte surface film has a dull surface appearance; that is, it is not shiny or glossy. Such a surface appearance is not typical of most biaxially oriented films used in packaging but is advantageous in that it provides an unusual appearance when reverse printed on the side opposite to the matte surface.
U.S. Pat. No. 5,492,757 to Schuhmann, et al. discloses an opaque, matte, multilayer polypropylene film having at least one base layer and at least one interlayer, and an outer layer applied to this interlayer. The base layer includes polypropylene and fillers. The interlayer includes a mixture or blend of two components I and II, wherein component I is a propylene homopolymer or a copolymer of &agr;-olefins having 2 to 10 carbon atoms, or a terpolymer of &agr;-olefins having 2 to 10 carbon atoms, or a mixture or blend of these polymers and component II is a high density polyethylene (HDPE) or a blend of HDPE and a propylene homopolymer or copolymer of a copolymer of &agr;-olefins having 2 to 10 carbon atoms, or a terpolymer of &agr;-olefins having 2 to 10 carbon atoms, or a mixture or blend of these polymers. The outer layer essentially includes a copolymer of &agr;-olefins having 2 to 10 carbon atoms, or a terpolymer of &agr;-olefins having 2 to 10 carbon atoms, or a mixture or blend of these polymers.
U.S. Pat. No. 5,494,717 to Peiffer, et al. discloses a heat-sealable, shrinkable multilayer film which comprises at least one base layer containing a propylene polymer or a propylene polymer mixture and at least one outer layer which comprises a mixture or blend of two components I and II, wherein the mixture contains copolymers or terpolymers of &agr;-olefins having 2 to 10 carbon atoms and HDPE.
U.S. Pat. No. 5,496,600 to Peiffer, et al. discloses a multilayer polypropylene film which contains at least one base layer containing polypropylene or a polypropylene mixture and resin, and at least one outer layer which contains a mixture or blend of two components I and II.
U.S. Pat. No. 5,516,563 to Schumann, et al. discloses an opaque, matte, multilayer polypropylene film including at least one base layer comprising polypropylene or a polypropylene mixture and fillers, and at least one outer layer which contains a mixture or blend of two components I and II.
Similarly, U.S. Pat. No. 5,618,369 to Peiffer, et al. discloses a matte multilayer polypropylene film which includes at least one base layer containing polypropylene and migrating additives or a mixture of migrating additives, and at least one outer layer which includes a mixture or blend of two components I and II.
SUMMARY OF THE INVENTION
The present invention is directed to a matte surface film comprising:
(a) a base layer comprising a polyolefin; and
(b) a void free matte surface layer comprising a blend of a non-hydrocarbon polymer with at least one incompatible polyolefin, wherein said non-hydrocarbon polymer includes monomeric units with polar functional groups; and wherein said blend comprises at least 12 wt % of said non-hydrocarbon polymer.
In a preferred embodiment of the present invention, the blend of the incompatible polymers contained in the matte surface layer comprises (i) a propylene homopolymer or propylene interpolymer and (ii) an ethylene vinyl alcohol copolymer.
DETAILED DESCRIPTION OF THE INVENTION
The matte surface layer is formed by providing a blend of two or more incompatible polymers. One of these incompatible polymers includes a non-hydrocarbon polymer. By the expression, non-hydrocarbon polymer, it will be understood that such a polymer includes at least one element other than hydrogen or carbon. In particular, these non-hydrocarbon polymers will include one or more monomeric units with at least one polar functional group. It will be understood that these non-hydrocarbon polymers are formed from monomers, wherein at least some of these monomers have polar functional groups.
Examples of such polar functional groups include hydroxy (OH), amide (CONH), carboxyl (COOH), acid anhydride [C(O)O(O)C], ester, carbonate, ketone and halogen.
Examples of particular non-hydrocarbon polymers include polyvinyl alcohol (PVOH); ethylene-vinyl alcohol copolymers (EVOH); ethylene-vinyl acetate copolymers (EVA); ethylene-vinyl acetate-vinyl alcohol copolymers; polyamides, especially nylons; polyesters, such as polyethylene terephthalate (PET) and polyethylene terephthalate/glycol (PETG); polycarbonate; maleic anhydride modified polyolefins; and polyvinyl chloride (PVC). A particular example of such a polymer is an ethylene-vinyl acetate-vinyl alcohol copolymer polymer identified as ECG-156B from EVAL Company of America. ECG-156B has a specific gravity of about 1.12, has a melting point of about 160° C. and contains about 48 mol % of ethylene.
As pointed out in U.S. Pat. No. 5,888,714 to Bourdelais, et al., particularly at column 4, lines 25-67, certain polymers can become void-initiating materials when blended with other polymers. Examples of such blends include certain nylons or certain types of polybutylene terephthalate dispersed in certain types of polypropylene. These blends are melt-mixed and the dispersed polymer forms dispersed spherical particles as the mix is cooled. When an extruded film of such a cooled mix is then stretched, the matrix polymer breaks away from the spherical particles, generating voids or cavities in the film.
In the present matte surface films, the formation of voids or cavities is avoided by proper selection of materials and conditions. For example, when the non-hydrocarbon polymer is present as more of a major component of the blend, the melted mix tends to form more of a continuous phase. In particular, depending on the choice of materials, the non-hydrocarbon polymer could form discrete beads or dispersed spheres at concentrations of less than 8 wt % of the blend. Furthermore, such beads or spheres may be too hard or too small to deform upon stretching such that the matrix polymer breaks away to form voids. At non-hydrocarbon polymer concentrations of 12 wt % or more, such discrete beads or dispersed spheres may have less of tendency to form, and to the extent that they do form, they are large enough to stretch along with the matrix polymer without forming voids. Preferred blends for forming the present matte surface films include those with 20 wt % or more of non-hydrocarbon polymer. For example, the blends may have 20 to 80 wt % of non-hydrocarbon polymer and 20 to 80 wt % of polyolefin.
Void formation can also be avoided by selecting a non-hydrocarbon polymer with a melting point nearly the same or less than the melting point of the matrix polymer. Therefore, preferred non-hydrocarbon polymers in the present matte surface films have a melting point of no greater than 10° C. higher than the melting point of the polyolefin. In contrast, void initiating polymers described in U.S. Pat. No. 5,888,714 to Bourdelais, et al., include cross-linked polymers.
To the extent that cross-linked polymers have melting points, such melting points tend to be extremely high. Often, cross-linked polymers do not melt, but they start to decompose at high temperature. Examples of non-hydrocarbon polymers in the present matte surface films have a melting point of no greater than 240° C.
The non-hydrocarbon polymer and polyolefin
Harley Lyle J.
Lu Pang-Chia
Tran Francis D.
ExxonMobil Oil Corporation
Jackson Monique R
James Rick F.
Santini Dennis P.
Thibodeau Paul
LandOfFree
Matte surface 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 Matte surface film, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Matte surface film will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3217659