Patent Application
20110250368
The present invention relates to adhesive and non-adhesive articles and methods of making the same. More particularly, the articles, or films, described herein are fire retardant and do not contain polyvinyl chloride (“PVC”) or halogen elements. Halogen elements refer to a series of nonmetal elements from Group 17 IUPAC Style (formerly: VII, VIIA) of the periodic table, comprising fluorine, (F); chlorine, (Cl); bromine, (Br) and iodine (I). The articles can be used in a variety of applications which require printability, flame retardancy, and embossability, including for example, wall covering, signs, graphics, pressure sensitive products, and the like.
Polyvinyl Chloride (PVC) films are widely used in such applications as wallcoverings, graphic decoration and etc. due to their cost advantage and superior properties in durability, printability and inherent fire-safety. However, the environmental concerns over the use of PVC material, e.g. releasing of toxic dioxins upon burning and water pollution from its phthalates plasticizer, have largely driven the development of PVC-alternative films. A PVC replacement film with integrated flame retardancy would be essential for applications such as wallcoverings. Flame retardants are materials that inhibit or resist the spread of fire. The common non-PVC polymeric materials do not readily have properties like PVC, especially in printability and flame retardancy. In this application, fire retardants and flame retardants are used interchangeably. Fire retardancy and flame retardancy are used interchangeably.
Accordingly, there is a need for environmentally friendly, flame retardant, non-PVC films that have properties that are comparable with PVC films. The present invention satisfies this need.
The present invention includes various compositions, films made from the compositions, film laminates and related methods. An exemplary embodiment is a composition that is configured for use in creating films. The composition includes vinyl acetate containing polymer, nonhalogen flame retardants and at least one additive that is a pigment, a surfactant, a dispersant, a wetting agent, a defoamer, a coupling agent, a solvent, a UV absorber, or a light stabilizer. A vinyl acetate containing polymer refers to vinyl acetate copolymer or homopolymer or the mixture of the two. An exemplary vinyl acetate copolymer is Vinyl Acetate Ethylene (VAE) Copolymer. The Vinyl Acetate Ethylene (VAE) Copolymer is a product based on the copolymerization of vinyl acetate and ethylene in which the vinyl acetate content can range between 60-95%, and the ethylene content ranges between 5-40% of the total formulation. This product should not be confused with the ethylene vinyl acetate (EVA) copolymers in which the vinyl acetate generally range in composition from 10-40%, and ethylene can vary between 60-90% of the formulation. VAEs are water-based emulsions, whereas EVAs are solid materials used for hot melt and plastic molding applications. VAEs are also sold in powder form, a technology pioneered in Europe.
Another exemplary embodiment of the invention includes compositions comprising (a) an emulsion polymer selected from the group consisting of a vinyl acetate homopolymer or copolymer or the mixture of, an acrylic copolymer or its mixture with a VAE copolymer, a VAE and acrylic hybrid, a styrene copolymer, a polyurethane containing polymer or a biodegradable polymer; and (b) flame retardant additives, e.g. a combination of carbonifics, acid catalyst and blowing agent in fine powder form. Another exemplary embodiment further comprises (c) TiO2; and (d) hydrophobic copolymer dispersant. In another embodiment, latex or CaCO3 (calcium carbonate) is used in replace of TiO2 pigment in the composition thereby making the film less costly without necessarily compromising film opacity of the same film gauge.
Another exemplary embodiment is a film including (a) an emulsion polymer selected from the group consisting of a vinyl acetate homopolymer or copolymer or the mixture of, an acrylic copolymer or its mixture with a VAE copolymer, a VAE and acrylic hybrid, a styrene copolymer, a polyurethane containing polymer and a biodegradable polymer, (b) nonhalogen flame retardants and (c) at least one additive that is a pigment, a surfactant, a dispersant, a wetting agent, a defoamer, a coupling agent, a solvent, a UV absorber, or a light stabilizer. Another exemplary embodiment is a film that further includes at least one substrate layer. In a further embodiment, the film further includes a backing layer which is a scrim layer or a fabric layer and the film is a wallcovering film.
One exemplary method of making the film of the present invention comprises the steps of (a) making a composition comprising (i) polyvinylacetate ethylene copolymer; (ii) TiO2; and (iii) flame retardant additives; and (b) applying the composition through a coating method over a polyolefin substrate. In another exemplary embodiment, the composition was cast onto a PET film and subsequently peeled off to form a stand-alone film which was then laminated to a polyolefin film.
The flame retardant non-PVC films of the present invention can be readily laminated, e.g. adhesive lamination, onto scrim and fabrics to form a wall-covering construction. The printable and conformable non-PVC films in a wall-covering construction can also accommodate subsequent printing and embossing processes if needed. A thin coating layer and consequently a thin film can be achieved when the flame retardants are grinded to particle size less than 12 micron-meters. In addition, film opacity can span a broad range through modification by adding appropriate types and amount of pigments. The flame retardant non-PVC films could also be used in the manufacturing of adhesive labels, tapes and decorative sheets, and for a variety of other applications, including but not limited to applications where PVC films are generally used.
Another exemplary embodiment is an assembly that includes a liner, a pressure sensitive adhesive, a substrate layer and a print layer. The substrate layer includes a material that is a polyolefin or its copolymer or the mixture of, blend of cross linkable vinyl acetate copolymer with a VAE emulsion, a polyurethane emulsion, or a blend of polyurethane containing emulsions.
Other features of the invention should become apparent to those skilled in the art from the following description of the preferred embodiments taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention, the invention not being limited to any particular preferred embodiment(s) disclosed.
These, as well as other features, aspects, and advantages of this invention, will be more completely understood and appreciated by referring to the following more detailed description of the presently preferred exemplary embodiments of the invention in conjunction with the accompanying drawings, of which:
Unless otherwise indicated, the illustrations in the above figures are not necessarily drawn to scale.
The present invention is now illustrated in greater detail by way of the following detailed description that represents the best presently known mode of carrying out the invention. However, it should be understood that this description is not to be used to limit the present invention, but rather, is provided for the purpose of illustrating the general features of the invention.
The invention relates to composition and manufacture of polyvinyl chloride (“PVC”) replacement films. The films of the present invention do not contain PVC and hence are called non-PVC films. The non-PVC films offer the advantage of being environmentally friendly and having the property of durability, printability and flame retardancy of PVC films. The non-PVC films of the present invention have properties and performance that are comparable to, or exceed, those of the PVC films, and are suitable for applications where PVC films are generally used, including for example, wall covering, signs, graphics, pressure sensitive products and the like.
The adhesive layer 20 generally can be classified into the following categories: random copolymer adhesives such as those based upon acrylate and/or methacrylate copolymers, α-olefin copolymers, silicone copolymers, and the like; and block copolymer adhesives including those based upon linear block copolymers (i.e., A-B and A-B-A type), branched block copolymers, star block copolymers, grafted or radial block copolymers, and the like, and natural and synthetic rubber adhesives.
A description of useful pressure-sensitive adhesives can be found in Encyclopedia of Polymer Science and Engineering, Vol. 13. Wiley-Interscience Publishers (New York, 1988). Additional descriptions of useful pressure-sensitive adhesives can be found in Encyclopedia of Polymer Science and Technology, Vol. 1, Interscience Publishers (New York, 1964).
The liner 10 is preferably an ultrathin or ultra light liner having a thickness of less than 1.02 mil (0.0255 mm), less than 1 mil (0.0254 mm), less than 0.8 mil (0.0203 mm), less than 0.6 mil (0.015 mm), less than 0.50 mil (0.013 mm), or equal to or less than 0.25 mil (0.00626 mm) Such thin liners are commercially available as HOSTAPHAN® polyester film (e.g., 0.5 mil, 0.0127 mm, Tradename 2SLK silicone coated film) sheeting from Mitsubishi Chemical Company of Tokyo Japan. Another liner material is provided by Avery Dennison Corporation of Pasadena, Calif. as a 1.02 mil (0.026 mm) polyester backing sheet with a 1.25 mil (0.032 mm) adhesive layer.
The substrate layer 30 can include any polymeric film that is PVC-free. Such films include, for example, without limitations, polyolefins, PET, polycarbonates, polystyrene or its copolymers and biodegradable polymers such as polylactic acid. The polyolefin film is preferred to be polypropylene or its copolymer or a mixture of When coating process is desired to make the substrate layer, the substrate layer can be made from a coatable composition such as blend of cross linkable vinyl acetate copolymer, VAE emulsions, a polyurethane containing emulsions or any other non-PVC polymer films.
The print layer 40 can include in exemplary embodiments nonhalogen fire retardants mixed with a vinyl acetate containing polymer, a blend of vinyl acetate with VAE, a VAE/acrylic hybrid, an all acrylic formulation, a styrene copolymer or a VAE emulsion.
The exemplary embodiments of composition and film 5 of the present invention include at least one of the following:
(1) Vinyl acetate ethylene (“VAE”),
(2) VAE-acrylic hybrid
(3) Vinyl acetate homopolymer,
(4) Blend of VAE and vinyl acetate homopolymer,
(5) Blend of VAE and vinyl acetate copolymer,
(6) Blend of VAE with polyurethane,
(7) Blend of VAE with acrylic copolymer,
(8) Cross linking of VAE by adding small content of silane,
(9) Acrylic copolymer
(10) Polyurethane containing polymer, and/or
(11) Blend of Polyurethane and acrylic
(12) Styrene copolymer
(13) Polylactic acid
In other embodiments, a pigment, e.g., Titanium dioxide (“TiO2”) and/or other pigments, can be added to any of the above thirteen embodiments of composition and film of the present invention. The opacity of the film 5 depends on the amount of TiO2 or other materials. In another embodiment, the pigment, e.g., TiO2, can be replaced with latex such as ROPAQUE™ OP-96 or ULTRA-OPAQUE, made by Rohm and Haas of Philadelphia, Pa. In another embodiment, pigment like TiO2 may not be included if a clear film is desired. In a further embodiment, CYMEL® 385 by Cytec Industries Inc. of West Paterson, N.J. can be used as a cross-linker to increase the tensile strength of the film. In another embodiment used for nonprinting applications, wax emulsion, e.g., MICHEM® GUARD 55 from Michelman of Cincinnati, Ohio, can be added to any of the above ten embodiments of composition and film, thereby providing the property of ease-of-cleaning to the film. In yet another embodiment, wax emulsion, e.g., MICHEM® EMULSION 47950 from Michelman can be added to any of the above thirteen embodiments of composition and film of the present invention, and the manufactured film can be useful for anti-graffiti applications. In yet another embodiment, silica particles can be added to any of the above formulations to create an inkjet printable film for water based ink. Water based ink provides better environmental protection than solvent based inks. In another embodiment, the polystyrene copolymer is styrene-butadiene copolymer.
In other embodiments, the carboxyl containing components of the print layer are crosslinkable using polyaziridine, for example, XAMA®-7 from Lubrizol. The hydroxy containing components are crosslinkable using polyaziridine or melamine formaldehyde, e.g. CYMEL® 385 from Cytec Industries Inc. Other crosslinkers known to the skilled in the art can also be used to cross link the print layer components.
Another important component for film 5 is nonhalogen flame retardants. In some applications such as wall-covering, flame retardancy is an important property and a product must meet the flame retardancy requirement. There are many commercially available flame retardants that can be used to provide the flame retardancy of a product. However, most of the commercial flame retardants are halogen based. Adding a halogen based flame retardants would negatively impact the environmental friendliness of the non-PVC film. For some of the non-halogen based flame retardants, its lack of compatibility with the base film formulation and its negative impact on the film mechanical properties and adhesion to other layers of the construction can make the formulation and process difficult.
To meet the flame retardancy requirement of the non-PVC film, a non-halogen based flame retardant or a mixture of non-halogen flame retardants can be added to any of the thirteen formulations. The nonhalogen fire retardant is preferred to be a combination of carbonifics, acid catalyst and blowing agent in fine powder form. Such non-halogen flame retardants includes penta erythrital, ammonium polyphosphate, urea and melamine based chemicals. JLS-Pent, JLS-APP101 and JLS-Melamine from JLS Chemical, California are examples of such flame retardants. The flame retardants need to be processed first into fine particles before being mixed with the non-PVC film formulation. The particle size is preferred to be less than 12 micron meters. It is more preferred to be less than 6 micron meters. The flame retardants can be 30 to 60% of the total formulation of the print layer. In one embodiment of the invention, nonhalogen flame retardants were added to the print layer only. In another embodiment of the invention, nonhalogen flame retardants were added to both the print layer and the substrate.
The film 5 of the present invention can be formed by preparing a liquid formulation or emulsion of an embodiment of composition of the present invention and then coating, such as by curtain coating, a substrate with the formulation or emulsion. In one embodiment, the substrate is a liner. After drying of the film, the film can be peeled off the liner as a stand alone film which gets laminated with a substrate later on. In another embodiment, the substrate is a polyethylene terephthalate (“PET”) film. In yet another embodiment, the substrate is a polyolefin film. To improve adhesion between the print layer and the substrate, the substrate can be corona treated. A primer layer can also be coated on the substrate to improve adhesion. Such primer layer can be any coating that can improve adhesion of the print layer to the substrate. One example is the MICA A-131-X, a 5% polyethylenimine (PEI) solution from Mica Corporation, Shelton, Conn.
An exemplary method of making a film according to the present invention is illustrated in the flowchart 50 of
Adhesives can be applied to one or both major surfaces of the film 5 using known processes, such as, for example, adhesive lamination. Halogen free adhesives can be used to produce halogen-free films. Examples of halogen-free adhesives include acrylic adhesives such as a hot-melt acrylic adhesive and a water-based latex acrylic adhesive. Other halogen-free adhesives include a hot-melt rubber adhesive, a silicone adhesive, thermoplastic elastomers, other halogen-free adhesives known in the art, and any combination of any of these in any proportion.
In an exemplary embodiment of the composition of present invention, the polymeric material includes vinyl acetate containing polymer with a vinyl acetate content of at least about 75%, flame retardant additives, a pigment, and a dispersant. In yet another exemplary embodiment of the composition, the polymeric material includes a vinyl acetate containing polymer with a vinyl acetate content of at least 75%, flame retardant additives, a pigment, a dispersant, a wetting agent, and an ultra-violet light (“UV”) stabilizer.
The properties of the composition and film 5 of the present invention can be characterized by various analytical techniques. A brief description of these analytical techniques is given below:
The printability is tested by printing directly on the film specimen using solvent based or water based ink-jet printer as well as water based gravure printer. Visual inspection is performed to determine if there was smudging of ink on the surface of the film and diffusion of ink inside the film. Good printing is obtained if there is no smudging and diffusion of ink.
A vertical feasibility test was used. The coated film was cut into 2′×4′ strip and made as a loop by connection both ends. The flame from a match was set under the loop. It was considered pass the test if the film was resistant to the flame for a few seconds. Normally PP film will be ignited as soon as the flame was put under the looped film.
The following examples describe the various embodiments of the present invention. Numerous modifications and variations within the scope of the present invention will be apparent to those skilled in the art and the present invention is not limited to the examples given below. Unless otherwise states, all parts, percentages, and ratios reported in the following examples are on a weight basis, and all reagents used in the examples were obtained, or are available, from the chemical supplier identified below, or can be synthesized by conventional techniques.
The following Table 1 provides a list of chemicals used in the following examples, identifying their supplier; function; chemical name, formula or type; percentage solids; and Tg.
In a container, the following mixtures were prepared:
(A) 48 parts of water
(B) 5 parts of JLS-Melamine
(C) 7 parts of JLS-Penta
(D) 10 parts of JLS-APP101
(E) 0.6 parts of Rheolate® 350 and 0.6 parts of water
(F) 0.17 parts of Drewplus® Y-250
The mixture was ball milled until the particle size is higher than 7 in Hegman (i.e., less than 12 micron), prefer higher than 7.5 in Hegman (<6 micron).
71.37 parts of the flame retardant additives from example 1 was then charged to a jar and post-added the following under agitation:
(A) 24.5 parts of Vinnapas® 460,
(B) 2 parts of Disponil® AFX 4030
(C) 0.2 parts of Superwet 22S
(D) 0.4 parts of Tamol™ 731A
(E) 5 parts of Kronos® 4311
The resulting mixture has 41.2% solids. A non-PVC film was made by coating the mixture on the 7.5mil PP film from Profol Inc. The coating procedure is as following:
(1) corona treat the PP film to 47 dyne/cm
(2) coat the PP film with Polyethylenimine (PEI) primer solution at about 0.2 gsm using Meyer Rod #1.5.
(3) coat the primed PP with the mixture made above
(4) dry at 75° C. over 5 minutes.
The resulting dried topcoating is 2.5 mil. It shows good adhesion to the primed PP, good water based gravure printing, embossing, and flame retardant using the vertical feasibility test. This film can also be digitally printed by Mimaki solvent ink jet printer (GP-604S).
Same as Example 2 except Joncryl 80 was used in A instead of Vinnapas 460 and Xama-7 was used in D instead of Tamol™ 731A. The resulting formulation shows good adhesion to the corona treated PP without PEI primer after drying in the 75° C. over 5 minutes. This coated film also shows good embossing, gravure printing, and flame retardant properties.
Same as Example 2 except Gasil 23F was used instead of Tamol 731A in D and 56.6 parts (39% solids) of Example 1 was used instead of 71.37 parts (31.4% solids). The formulation was coated over a corona treated and PEI primed PP film. The resulting coated film shows that it is desktop ink jet printable. The color density is Cyan 1.15, magenta 1.01, yellow 1.03 and black 1.11 measured by Gretag Bacbeth SpectroEye.
Same as Example 2 except E was not used. The topcoat layer also has good adhesion to the primed PP.
Same as Example 2 except 24 parts of Vinnapas 465 was used instead of 24.5 parts of Vinnapas 460.
DS6D81 ethylene propylene copolymer from Dow Chemical, P8555SD TiO2 polypropylene masterbatch from A. Schulman, and NA217-000 low density polyethylene from Equistar have been used to create a base film for example 7-9. JLS-PNP1C, an ammonium polyphosphate based flame retardant from JLS chemical was incorporated into the film for flame retardancy.
The films were formed using the following procedures:
Instrument:
1. Twin screw extruder manufactured by Leistritz (model MICRO 27) and
2. Vibratory LWF style feeders made by K-Tron
Specifications:
1. 27 mm co-rotating screw, 500 rpm, and 40 L/D.
2. 9 heating zones
3. a side feeding zone located at zone 5.
Polyolefin and white masterbatch pallets were pre-mixed at desired ratio. The mixture was fed by a K-Tron feeder to the feeding zone. All compounding work was done at 180° C. to 200° C., the melting temperature.
Polymer melt from the twin screw extruder was directly fed into a 6″ die and cast onto a 3-roll stacks with cooling. The finished sheets were used for subsequent testing.
Example 6 solution was coated over primed sample of Example 8 at 2.5 mil. It also shows good printing, embossing and flame retardant properties.
All of the features disclosed in the specification, including the claims, abstract, and drawings, and all of the steps in any method or process disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in the specification, including the claims, abstract, and drawings, can be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/US2008/084812 | Nov 2008 | US | national |
This application is a Continuation-In-Part of International Patent Application No. PCT/US2008/84812 filed on Nov. 26, 2008, which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US09/56808 | 9/14/2009 | WO | 00 | 6/27/2011 |
