Patent Application
20070077420
The present invention relates to protective films and more particularly, relates to polyether aliphatic urethane films for protecting exposed surfaces.
It is well known that environmental hazards (such as dirt, dust, rocks, pebbles, sand, acid, road salt, UV light, water, bird droppings, detergents, humidity, weather and the like) can damage the surfaces of automobiles, trailers, boats, airplanes, and the like. This damage can cause fading, cracking, scratching, and discoloration of the surface, especially surfaces that have been painted or coated. For example, damage to the painted metal surfaces of many automobiles and the like can lead, ultimately, to the metal surface rusting thereby resulting is even further damage that may require replacement of the surface.
Various means have been developed in an attempt to reduce this damage. For example, a common method of protecting the exposed surfaces is to apply wax. However, this method suffers from numerous well-known disadvantages. One disadvantage of waxing is that the application of wax is labor intensive and must be repeated often. Additionally, the wax only provides minimal protection against colliding materials such as sand, pebbles, and the like.
Another known method of protecting surfaces is to apply a surface protection polymer film such as the surface protection film described in U.S. Pat. No. 6,844,112 to Inoue et al., which is hereby incorporated fully by reference. The known surface protection films typically feature a polymer film having a layer of pressure-sensitive adhesive disposed on one side. These protective films are typically available in thicknesses from approximately 0.001″ (approximately 0.0254 mm) to approximately 0.125″ (approximately 3.177 mm), and in widths from approximately 6″ (approximately 152 mm) and widths up to approximately 120″ (approximately 3,048 mm).
While the polymer film may include various polymers, polyester TPU, referred to herein as simply polyester, has typically been used in automotive application. One reason for choosing polyester based films is the common belief that polyester polymers generally have improved physical properties for a given hardness compared to other polymers.
While generally effective, these polyester based protective films suffer from several disadvantages. For example, there have been problems with the moisture resistance or hydrolytic stability of these polyester-based protective films. Hydrolysis is generally accelerated by temperature and acidic conditions. It is important to note that a large application for these surface protection films is for the leading edges hoods of automobiles. Automobile hoods are often exposed to high temperatures (both from environmental causes and from the heat generated by the automobile engine during normal use) as well acid rain. As a result, polyester based surface protection films suffer from an increased vulnerability to hydrolysis. Accordingly, improved hydrolytic stability is extremely important.
A further disadvantage of the known surface protection films is that they are susceptible to bacterias, fungi, and microorganisms. This is particularly problematic when the surface protection film is applied to the surface after the surface has been exposed to the environment for a substantial amount of time. In these cases, bacteria, fungus, and the like which was already on the surface can be difficult to remove and can grow underneath the surface protective film. Additionally, bacteria, fungus, and the like (for example from birds and insects) can accumulate on the exterior surface of the surface protective film. These organisms can discolor the surface protective film and can actually break down the polyester. Additionally, chemicals used to remove these organisms can damage the surface protective film or the surrounding, unprotected areas.
Accordingly, what is needed is an improved surface protection film and method of protecting a surface. The improved surface protection film should preferably have increased resistance to hydrolysis. Moreover, the improved surface protection film should be resistant to bacterias, fungi, and microorganisms.
It is important to note that the present invention is not intended to be limited to a system or method which must satisfy one or more of any stated objects or features of the invention. It is also important to note that the present invention is not limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.
According to one embodiment, the present invention features a film comprising a base layer having substantially planar upper and lower surfaces and a layer of a top coating disposed about and substantially coextensive with the upper surface of the base layer.
The base layer includes a polyether aliphatic urethane, preferably an aliphatic thermoplastic urethane (TPU) including no more than approximately 90% by weight polytetramethylene ether gycol (PTMEG) and most preferably having between approximately 35% to approximately 55% by weight PTMEG. The base layer may have a cross-sectional thickness of between approximately 0.0254 mm (1 mil) to approximately 5.08 mm (200.0 mil) and most preferably between approximately 0.0762 mm (3.0 mil) to approximately 0.508 mm (20.0 mil) or between approximately 1.016 mm (40.0 mil) to approximately 5.08 mm (200.0 mil).
The base layer may optionally include a microbiocide, an ultraviolet stabilizer, or a filler. Additionally, the base layer includes a plurality of layers. For example, the base layer may feature an external layer of polyether aliphatic urethane having the upper surface and an inner layer having the lower surface. The inner layer may optionally include at least one material selected from the group consisting of polyethylene, polypropylene, polyester, polyamide, regenerated cellulose fibers, semi-synthetic fibers and polyethylene terephthalate. Alternatively, the inner layer may include an ultraviolet protective film or a polarized film.
The top coating may feature at least one material selected from the group consisting of acrylic resin, urethane resin, polyester resin, fluroelastomers, and ultraviolet barrier particles. The top coating preferably has a cross-sectional thickness of less than approximately 0.0762 mm (3 mil). A second layer of the top coating may be disposed about and substantially coextensive with the lower surface of the base layer.
The film may further include means for securing the film to an exterior surface of an object. For example, hydrostatic adhesion or electrostatic adhesion may be used to secure the film. In the preferred embodiment, an adhesive layer (preferably a pressure sensitive adhesive) may be disposed about and substantially coextensive with the lower surface of the base layer. The adhesive layer may be applied directly to the exterior surface of the object with the film being applied to the adhesive layer afterwards. Alternatively, the adhesive layer may be applied directly to the lower surface of the base layer prior to securing the film to the exterior surface of the object. A release layer may be disposed about and substantially coextensive with an external surface of the adhesive layer to prevent adhesion prior to application of the film.
According to another embodiment, the present invention features a method of manufacturing a protective film. The method includes forming a base layer of a polyether aliphatic urethane having a substantially planar upper and lower surface. A layer of a topcoat is applied substantially coextensive with and contacting the upper surface of the base layer. An adhesive layer may optionally be applied substantially coextensive with and contacting the lower layer of the base layer.
According to yet another embodiment, the present invention features a method of manufacturing a substantially transparent panel. The method includes forming a base layer of a polyether aliphatic urethane having a substantially planar upper and lower surface and a cross-sectional thickness of between approximately 1.016 mm (40.0 mil) to approximately 5.08 mm (200.0 mil). A first layer of a topcoat compatible with the polyether aliphatic urethane of the base layer is applied substantially coextensive with and contacting the upper surface of the base layer. Optionally, a second layer of a topcoat is applied substantially coextensive with and contacting the lower surface of the base layer. The substantially transparent panel may be secured within a frame.
These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein:
According to one embodiment, the present invention features a surface protection film 10,
In the exemplary embodiment, the surface protection film 10 features a base layer or film 12 having a substantially planar upper and lower surface 13, 15. In contrast to the known prior art surface protection films, which are typically constructed from polyesters, the surface protection film 10 according to the present invention includes the unexpected realization that a base layer 12 featuring a polyether aliphatic urethane provides numerous benefits over polyester based surface protection films.
As discussed above, polyesters have traditionally been chosen for use in surface protective films based on, in part, the common belief that polyester polymers generally have improved physical properties for a given hardness compared to other polymers such as polyether polymers. Additionally, polyether polymers have traditionally been used in the manufacture of laminated glass (such as bullet-proof glass) and were designed to be soft and tacky. This has lead to the widely held belief that polyether polymers would not suitable for use in surface protection films.
In direct contradiction to these generally accepted beliefs, the surface protection film 10 according to the present invention features base layer 12 of a polyether aliphatic urethane. The use of a base layer 12 of polyether aliphatic urethane results in a protective film 10 having increased moisture resistance and hydrolytic stability compared to the known surface protection film, especially those made from polyester. As discussed above, increased hydrolytic stability is particularly beneficial for applications exposed to high temperatures and acid conditions such as those commonly experienced by automobiles and boats.
Additionally, the present invention features the unexpected realization that a base layer 12 of a polyether aliphatic urethane increases ultraviolet performance of the surface protection film 10. A QUV test (using a 313B bulb, 1.1 watt/m2 intensity, at a cycle of eight hours with radiation at 70° C., then four hours at 50° C. with 100% relative humidity) was conducted using the surface protection film 10 of the present invention and the prior art, polyester based films. After approximately 3 days, the surface protection film 10 of the present invention performed noticeably better than the prior art polyester based films.
Moreover, the present invention features the unexpected realization that a base layer 12 of a polyether aliphatic urethane results in a surface protection film having less gels/area compared to the prior art polyester based films. Tests were performed comparing the number of gels per area for the surface protection film 10 of the present invention and the prior art polyester based films. The results of these tests showed that the surface protection film 10 of the present invention had a significantly reduced number of gels compared to the prior art polyester based films. This reduced number of gels results in an enhanced aesthetic appearance for the surface protection film 10 according to the present invention.
A surface protection film 10 featuring a base layer 12 of polyether aliphatic urethane may also have antimicrobial, antibacterial, and/or antifungal properties. As a result, the surface protection film 10 may be less susceptible to degradation compared to the known surface protection films.
The polyether aliphatic urethane may feature any polyether aliphatic urethane known to those skilled in the art having the necessary hardness, toughness, tear strength, UV stability, haze, and light transmittance. The polyether aliphatic urethane also preferably has a sufficient optical clarity such as to not substantially change the color of the surface 11. These properties are to be determined based on the intended application of the surface protection film 10 and will vary widely based on the intended application of the surface protection film 10. Those skilled in the art will readily be able to determine these properties based on the intended application.
According to one embodiment, the base layer 12 features an aliphatic thermoplastic urethane (TPU) containing no more than approximately 90% by weight polytetramethylene ether glycol (PTMEG). As the percent weight of the PTMEG is increased, the resulting aliphatic TPU becomes softer. The exact amount of PTMEG will again depend on the intended application of the surface protection film 10 and is within the knowledge of one of ordinary skill in the art. According to the exemplary embodiment, the percent PTMEG by weight is between approximately 35% and approximately 55%.
The base layer 12 may be formed using any method known to those skilled in the art. For example, the base layer 12 may be flat die or film blown die extruded. The thickness of the base layer 12 will be determined based on the intended application of the surface protection film 10, but for illustrative purposes the base layer 12 is preferably between approximately 0.0254 mm (1 mil) to approximately 5.08 mm (200.0 mil) and most preferably between approximately 0.0762 mm (3.0 mil) to approximately 0.508 mm (20.0 mil).
It is important to note that the base layer 12 may also feature other additives and modifiers. For example, the base layer 12 may include one or more microbiocides, UV stabilizers, fillers, and/or processing additives. Additionally, surface protection film 10,
The surface protection film 10,
The topcoat 14 may be applied to the base layer 12 in any manner known to those skilled in the art. For example, the topcoat 14 may be applied by immersing the base layer 12 in a solution containing the topcoat 14, spraying a solution containing the topcoat 14 onto the base layer 12, or applying a solution containing the topcoat 14 to the base layer 12 by gravure coating, reverse coating, laminating, casting, co-extrusion, or by any of the methods described in U.S. Provisional Application Ser. No. 734,503, filed Nov. 8, 2005, or U.S. Provisional Ser. No. 60/734,502, filed Nov. 8, 2005, both of which are fully incorporated herein by reference. Although the thickness of the topcoat 14 may be arbitrarily determined, it is preferably 0.0762 mm (3 mil) or less. Additionally, the topcoat 14,
While the surface protection film 10 could be held in to the surface 11 using hydrostatic or electrostatic adhesion or lamination, the surface protection film 10 is preferably secured to the surface 11 by way of an adhesive layer 16. According to one embodiment, the adhesive layer 16 is applied to the lower surface 15 of the base layer 12 at the factory. Alternatively, the adhesive layer 16 may be applied directly to the surface 11, and the surface protection film 10 (i.e., the base layer 12 and the topcoat 14) may then be placed on the adhesive layer 16.
In either embodiment, the adhesive layer 16 may include any adhesive known to those skilled in the art. According to the exemplary embodiment, the adhesive is a pressure sensitive adhesive, preferably an acrylic based adhesive with anti-yellowing properties. Alternatively, the adhesive layer 16 may include an appropriate rubber-based pressure-sensitive adhesive. When a rubber-based pressure-sensitive adhesive is used, it is preferable to select one comprising an aliphatic rubber polymer containing no or few unsaturated bonds, from the viewpoint of establishing a long-lasting and stable function, etc. Examples of such a rubber type polymer include polyisobutylene, butyl rubbers, A-B-A type block polymers such as styrene-ethylene/butylene copolymer-styrene (SEBS), styrene-ethylene/propylene copolymer-styrene (SEPS), styrene-butadiene-styrene (SBS) and styrene-isoprene-styrene (SIS), or hydrogenated products, and ethylene/vinyl acetate copolymer. In the exemplary embodiment, the adhesive layer 16 is preferably chosen such that the adhesive layer 16 remains secured to the base layer 12 when the surface protection film 10 is removed from the surface 11.
One or more base polymers can be used to prepare the pressure-sensitive adhesive. It is particularly preferable to use two or more base polymers having different molecular weight distribution. In the case of A-B-A type block polymers, it is preferable to use one comprising monomers having different molecular weight distribution or one having different styrene content, or to use the A-B-A type block polymers in combination with A-B type diblock polymers such as styrene-ethylene/butylene copolymer (SEB), styrene-ethylene/propylene copolymer (SEP), styrene-butadiene (SB) or styrene-isoprene (SI).
In the preparation of the pressure-sensitive adhesive, it is also possible to add appropriate tackifiers to control the adhesive characteristics thereof, etc., if needed. Examples of the tackifiers include terpene resins such as .alpha.-pinene polymers, .beta.-pinene polymers, diterpene polymer and alpha.-pinene/phenol copolymer; hydrocarbon resins such as aliphatic and aromatic resins and aliphatic and aromatic copolymers; rosin resins; coumarone and indene resins; (alkyl)phenol resins; and xylene resins. It is important to note that the examples given above are for illustrative purposes only; those skilled in the art will recognize that this list is not exhaustive and that other possibilities exist and are considered within the scope of the present invention.
Moreover, if needed, appropriate softeners suitable for the base layer 12 may be used to control the adhesive properties. Examples of these softeners include low molecular weight polyisobutylene and polybutene for the polyisobutylene, and paraffin oils for the A-B-A type block polymers. In addition, appropriate additives such as fillers, pigments, aging inhibitors and stabilizers may be used, if necessary.
The adhesive layer 16 may be applied to the lower surface 15 of the base layer 12 in any manner known to those skilled in the art. For example, the adhesive layer 16 may be applied by immersing the base layer 12 in a solution containing the adhesive layer 16, spraying a solution containing the adhesive layer 16 onto the base layer 12, or applying a solution containing the adhesive layer 16 to the base layer 12 by gravure coating, reverse coating, laminating, casting, co-extrusion, or by any of the methods described in U.S. Provisional Application Ser. No. 734,503, filed Nov. 8, 2005, or U.S. Provisional Ser. No. 60/734,502, filed Nov. 8, 2005. Although the thickness of the adhesive layer 16 may be arbitrarily determined and will vary depending on the intended application of the surface protection film 10, the adhesive layer 16 preferably ranges from between approximately 0.00254 mm (0.1 mil) to approximately 0.1016 mm (4.0 mil), preferably approximately 0.0127 mm (0.5 mil) to approximately 0.0762 mm (3.0 mil), most preferably approximately 0.0381 mm (1.5 mil). Additionally, the adhesive layer 16 may also feature multiple layers of either the same or different materials.
The surface protection film 10,
According to another embodiment, the surface film 100,
According to this embodiment, the surface film 100 preferably features at least one base layer 12 as described above and one or more topcoats 14 as described above. The protective film 100 according to this embodiment is preferably constructed thicker (preferably between approximately 1.016 mm (40 mil) to approximately 5.08 mm (200.0 mil)) to increase the overall strength. According to one embodiment, the surface film 100 features a single topcoat 14′, preferably disposed on the upper or top surface 13 of the base layer 12. Alternatively, the surface film 100 may also feature a second topcoat 14″ dispose on the bottom or lower surface 15 of the base layer 12. This embodiment is particularly useful in applications where both the upper and lower surfaces 13, 15 of the base layer 12 would otherwise be exposed. The surface film 100 may be secured within a framework of a canvas, vinyl, or the like by way of stitching, adhesive, ultrasonic welding, hook and loop fasteners, and the like.
Based on the above description, the film according to the present invention preferably features a base layer of polyether aliphatic urethane, and a topcoat and optionally includes an adhesive layer. The use of a base layer of polyether aliphatic urethane provides the unexpected benefits of improved moisture resistance and hydrolytic stability, and/or microorganisms, despite the widely held belief that polyether aliphatic urethane was unsuitable for use as a protective film.
As mentioned above, the present invention is not intended to be limited to a system or method which must satisfy one or more of any stated or implied object or feature of the invention and should not be limited to the preferred, exemplary, or primary embodiment(s) described herein. The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as is suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the claims when interpreted in accordance with breadth to which they are fairly, legally and equitably entitled.
The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/723,872, filed on Oct. 5, 2005.
| Number | Date | Country | |
|---|---|---|---|
| 60723872 | Oct 2005 | US |
