Abstract:
A stain resistant film construction that includes a polyvinyl film laminated to a polyolefin film by an adhesive. The stain resistant film construction can be formed into a retroreflective product that includes a polyolefin layer, an adhesive layer and a polyvinyl layer attached to the polyolefin layer by the adhesive on the first side of polyvinyl layer. Retroreflective prisms can be attached to the second side of polyvinyl layer, and a backing layer can be attached to the second side of polyvinyl film through the prism layer.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/188,118, filed on Mar. 9, 2000. The entire teachings of the provisional application are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Flexible film retroreflective products are commonly used as tapes or patches on clothing for safety and decorative purposes. Soft flexible face films, such as polyvinyl chloride or polyurethane, are normally preferred for applications, because they tend to be the least restrictive to the wearer&#39;s movement. Under certain conditions, however, these materials can become stained in the laundering process. 
     SUMMARY OF THE INVENTION 
     The invention includes a stain resistant film construction that includes a polyvinyl film laminated to a polyolefin film by an adhesive. The stain resistant film construction can be formed into a retroreflective product that includes a polyolefin layer, an adhesive layer and a polyvinyl layer attached to the polyolefin layer by the adhesive layer on the first side of polyvinyl film. Retroreflective prisms can be attached to a second side of polyvinyl film, and a backing layer can be attached to the second side of polyvinyl film through the prism layer. 
     The present invention has the advantage that it provides for a solution for preventing the staining of polyvinyl materials when laundered with stain inducing fabrics. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a first embodiment of a stain resistant film construction. 
     FIG. 2 is a cross-sectional view of a second embodiment of the stain resistant film construction. 
     FIG. 3 is a cross-sectional view of a third embodiment of the stain resistant film construction. 
     FIG. 4 is a cross-sectional view of a fourth embodiment of the stain resistant film construction. 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. All parts and percentages are by weight unless otherwise specified. 
     As shown in FIG. 1, a layer of a polyolefin film  10 , preferably, polyethylene or polypropylene, is attached to a surface of a polyvinyl film  12  in order to form a barrier to a staining component of a fabric. A thin polyolefin film having a thickness that is sufficiently flexible to minimize the loss of desired softness and elongation in the product while maintaining a sufficient barrier. The preferred range of thickness is between about 6 and 125 micrometers. A more preferred thickness is between 10 and 40 micrometers. Preferred polyolefins include polyethylene, polypropylene, polybutylene, polybutenes, polyisoprene and copolymers thereof. The polyolefin film  10  can be attached to the polyvinyl film  12  by an adhesive  14 . Polyolefin film  10  can be attached with an adhesive  14 , such as a urethane adhesive, an ultraviolet light curing adhesive, a water-based adhesive or a solvent based adhesive, and a hot melt adhesive. 
     Polyvinyl sheeting product  20 , which is a retroreflective sheeting, is shown in FIG.  2 . Polyvinyl sheeting product  20  has polyvinyl sheeting  22 , which is formed from vinyl units. Examples of suitable materials include polyvinyl chloride, polyvinyl fluoride, polyvinylidene fluoride, and polyvinylidene chloride. The polyvinyl sheeting  22  can have plasticizers within the polyvinyl to allow flexibility and softness to the product. A preferred polyvinyl sheeting product is polyvinyl chloride. These plasticizers can leach from the polyvinyl film. When laundered, the plasticizers of the polyvinyl sheeting can react with numerous dyes that are present in the laundry water from other clothing articles that are washed at the same time. For example, the dyes from blue jeans can readily stain a polyvinyl sheeting during a laundering cycle. As a way of avoiding or minimizing staining, polyolefin film  24  is laminated or by other means attached to the layer of polyvinyl sheeting  22 . Preferably the films are laminated at a temperature as warm as possible without deforming the film. Polyolefin film  24  can be attached with an adhesive  26 , such as a urethane adhesive, an ultraviolet light curing adhesive, a water-based adhesive, a solvent based adhesive, and a hot melt adhesive. A preferred polyolefin is available from Mobil Chemical Company under the name of Bicor. It is a coextruded polypropylene film with an acrylic top coat or layer and surface treatment to promote lamination or print adhesion. In one embodiment, suitable polyvinyl sheeting is in the range of between about 50 and 508 micrometers (two and twenty mils) in thickness. In a preferred embodiment, the polyvinyl material is between 152 and 254 micrometers (six and ten mils) in thickness. 
     Cast on the second side of the polyvinyl sheeting are prisms  28  that can be attached by methods known in the art including U.S. Pat. No. 3,684,348, issued to Rowland on Aug. 15, 1972 and U.S. Pat. No. 3,689,346, issued to Rowland on Sep. 5, 1972. The teachings of each patent are incorporated herein by reference. For example, the prisms  28  can include polyvinyl. Prisms can also be formed of hard materials, such as polyurethane, polycarbonate or polyacrylate. The prisms can be attached to the polyvinyl film by a suitable method, such as described in U.S. application Ser. No. 08/976,095, filed on Nov. 21, 1997, now issued as U.S. Pat. No. 6,039,909 on Mar. 21, 2000, which corresponds to International Publication WO96/36480, published on Nov. 21, 1996. The teachings of each patent are incorporated herein by reference. The prisms that are attached to the polyvinyl film are typically cube corner prisms but can also include linear prisms. In one embodiment, the cube-corner prisms can have a pitch in a range of between about 38 and 254 micrometers (1.5 and ten mils). In a preferred embodiment, the cube-corner prisms can have a pitch in a range of between about 76 to 152 micrometers (three and six mils). 
     In another embodiment, as shown in FIG. 3, a polyvinyl backing layer or other suitable backing layer can be welded by radio frequency welding or other suitable methods to form air spaces  32  between polyvinyl sheeting and a backing layer  30  with prisms  28  attached to a side of polyvinyl within the air spaces  32  to form air-backed prisms. 
     In yet another embodiment, as shown in FIG. 4, the prisms are coated to form a metalized layer  34  with a reflective material, such as aluminum, silver or gold, and then laminated to a suitable backing layer  38 , such as a polymer film or a cloth, with a pressure sensitive adhesive or a heat activated adhesive. This laminate can be sewn onto a garment. In yet another embodiment, the laminate can be attached to the garment directly using the pressure sensitive adhesive or the heat activated adhesive. 
     EXAMPLE 1 
     A laminate of Mobil Bicor polypropylene film was laminated to a clear polyvinyl film and attached with a PN 03 polyurethane adhesive from Morton Chemical. On the polyvinyl side of the laminate acrylic prisms were cast and a soft white polyvinyl chloride backing film was radio frequency sealed to the prisms in first polyvinyl layer. The samples were washed with Clopman Sailor Blue dyed polyester cotton fabric at about 68° C. (155° F.) for about twenty-five minutes. A standard Reflexite polyvinyl tape product, Product No. GP330, was also included as a control. The polypropylene-faced tape showed no staining (ΔE&lt;8) while the normal Reflexite polyvinyl tape product was very blue in color (ΔE&gt;27). 
     EXAMPLE 2 
     A polyvinyl chloride film (approximately 254 micrometers (10 mils thick)) was coated with a layer of Bostik 7063 solvent adhesive crosslinked with Boscodur 16 (Both from Bostik Corp.). The solvent was evaporated and a 25 micrometers (one mil) thick layer of Mobil Bicor LBW was laminated to the adhesive surface. Retroreflective cube corners were cast onto the other side of the polyvinyl chloride and the structure was radio frequency sealed to a second layer of polyvinyl chloride to form air pockets around the retroreflective cube corners. 
     EXAMPLE 3 
     Vinyl film was coated with a ultraviolet curable composition of Sartomer SR981 and SR963 (Sartomer Corp.) with suitable photoinitiators. A 30.5 micrometers (1.2 mil layer) of Mobil Bicor LBW was laminated to the coating and the material was cured with ultraviolet light. A retroreflective multilayer tape product was made with this laminate in the same fashion as Example 1. 
     EXAMPLE 4 
     A comparative example of the retroreflective tape was made by the same method as used in Example 2, except that the layer of Mobil Bicor was not laminated to the surface. This material was used for the laundering tests in order to evaluate the effectiveness of the added polyolefin layer. 
     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.