Adhesive Delivery System

Abstract

The present invention is an adhesive delivery system that includes a conformable film having a top surface and a bottom surface, an adhesive releasably coated on at least a portion of the top surface of the conformable film, and a light release liner adhered to the adhesive side opposite the conformable film.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to adhesive delivery systems. In particular, the present invention is a system for delivering adhesive to a forming surface. [Background technology]

[0002] Die-cut or laser-cut adhesives are widely used as optical and / or bonding layers in electronic and automotive displays. As displays in both consumer electronics and automobiles become more complex and tend to take on new shapes, such as non-flat or curved, various materials and manufacturing methods must be developed to apply the adhesive to shaped surfaces. Adhesives used in electronic displays generally have a release liner on each surface to protect the adhesive until it is ready to be used. The release liners used to apply adhesives to electronic displays are typically rigid and dimensionally stable.

[0003] Various methods can be used to laminate an adhesive onto a surface. One method uses a roller laminator to laminate the adhesive onto 2D and 2.5D (curved at two opposite edges) display surfaces. In this method, the light release liner is removed from the adhesive, and one edge of the adhesive is aligned with a mating edge of the display layer surface. Supported by the support of the rigid heavy release liner, the roller precisely applies the adhesive to the display surface. Another method of laminating an adhesive onto a display surface is to use a vacuum laminator. In this method, the adhesive is fixed to an application surface and aligned above the display layer surface. The adhesive is then applied to the display surface under surface pressure in a vacuum environment.

[0004] While rigid liners provide effective support for adhesives when laminating to 2D and 2.5D surfaces, some problems can arise when laminating adhesives to 3D surfaces due to the potentially large deformations required for conformance and stresses that can buckle the liner material. One solution to the buckling problem is to use a less rigid liner or to thermally reduce the rigidity of the process liner during the lamination process. However, this can create quality issues at each step of the manufacturing process. When a less rigid liner is used, the adhesive and liner are pulled and adhered onto the display surface using a vacuum. Traditional liners can wrinkle as portions of the liner are pulled over the curved corners of the display surface. Lower rigidity liners allow for molding to curved surfaces, but can be limited in that they must be rigid enough to support the adhesive during the coating, conversion, and assembly processes. Summary of the Invention

[0005] In one embodiment, the invention is an adhesive delivery system that includes a conformable film having a top surface and a bottom surface, an adhesive releasably coated on at least a portion of the top surface of the conformable film, and a light release liner adhered to the opposite adhesive side of the conformable film. [Brief explanation of the drawings]

[0006] The present invention may be further explained with reference to the accompanying drawings. [Figure 1A] FIG. 1 is a bottom view of a first embodiment of a delivery system according to the present invention. [Figure 1B] 1 is a cross-sectional view of a first embodiment of a delivery system according to the present invention. [Figure 1C] 1 is an alternative cross-sectional view of a first embodiment of a delivery system according to the present invention. [Figure 1D] 1 is an alternative cross-sectional view of a first embodiment of a delivery system according to the present invention. [Figure 2] FIG. 10 is a bottom view of a second embodiment of a delivery system according to the present invention. [Figure 3] FIG. 10 is a bottom view of a third embodiment of a delivery system according to the present invention. [Figure 4] FIG. 10 is a bottom view of a fourth embodiment of a delivery system according to the present invention. [Figure 5A] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 5B] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 5C] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 5D] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 5E] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 5F] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 5G] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 5H] 1 is a flow chart of a first embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6A] 4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6B] 4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6C] 4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6D] 4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6E] 4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6F]4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6G] 4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 6H] 4 is a flow chart of a second embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7A] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7B] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7C] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7D] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7E] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7F] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7G] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7H] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7I] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7J] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7K] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 7L] 10 is a flow chart of a third embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8A] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8B] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8C] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8D] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8E] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8F] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8G] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8H] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8I] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8J] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8K] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8L] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8M] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8N] 10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 8O]10 is a flow chart of a fourth embodiment of a method for manufacturing an adhesive delivery system according to the present invention. [Figure 9A] 1 is a flow chart of adhesive laminating to a molding surface according to one embodiment of the present invention. [Figure 9B] 1 is a flow chart of adhesive laminating to a molding surface according to one embodiment of the present invention. [Figure 9C] 1 is a flow chart of adhesive laminating to a molding surface according to one embodiment of the present invention. [Figure 10] FIG. 10 is a side view of the setup where the adhesive is stretched on the pack before lamination. [Figure 11] FIG. 10 is a side view of the setup where the adhesive is clamped during the lamination process to stretch the adhesive on the pack. [Figure 12] 1 is a graph showing displacement as a function of pack hardness. DETAILED DESCRIPTION OF THE INVENTION

[0007] FIG. 1A shows a bottom view, and FIGS. 1B, 1C, and 1D show cross-sectional views of one embodiment of an adhesive delivery system of the present invention. The adhesive delivery system enables optical / display bonding of two substrates, at least one of which is shaped (e.g., curved or otherwise non-planar, including topography). That is, at least one of the substrates is curved out of plane in both the x-axis and y-axis. The adhesive delivery system generally includes an adhesive on a conformable film (also referred to as a conformable liner; these terms are used interchangeably throughout). The conformable film may be supported by a more rigid frame carrier to help overcome handling and precision issues associated with conformable films. The rigid frame carrier supports the lamination of the adhesive to the molded surface without liner stress buckling and resulting adhesive stacking defects. Furthermore, in one embodiment, the present invention provides a method and apparatus in which portions of the rigid frame carrier that are undesirable during use can be optionally removed by the consumer prior to use, thereby minimizing the steps required to apply the adhesive and reducing waste streams at the consumer level. FIG. 1B shows that the waste has been removed, and FIG. 1C shows that the waste has not been removed.

[0008] The adhesive delivery system of the present invention is particularly useful in the field of electronic display manufacturing. In the case of a flat film that conforms uniformly to a three-dimensional curved surface, the film may bend, stretch, and / or compress when contacting the mating surface, which may cause stress in both the film and the surface substrate. The deformation strain of the film may generate stress exceeding its yield strength, where the deformation strain does not fully recover when the stress is released, which is defined as plastic deformation. If the strain is recovered, the material is typically considered elastic or viscoelastic, meaning that the strain recovers over time. Materials such as polyurethane, for example, recover significantly better than polypropylene film at strain levels above about 10%. If the strain deformation is fixed, the stress level can be relaxed. If stress is maintained, the material may also generate creep strain, and the material continues to deform over time. Creep can occur at any given strain level when stress is present. In one embodiment, the conformable film is conformable to the surface of a three-dimensional (3D) electronic display layer. In this way, when the adhesive is applied to the display layer surface using the conformable film, the adhesive conforms uniformly to the surface without wrinkles or optical distortion.

[0009] The adhesive delivery system 10 of the present invention, as shown in the figures, includes a heavy release liner 12 having a top surface 14 and a bottom surface 16 with release properties, an adhesive 18 coated on at least a portion of the top surface 14 of the heavy release liner 12, and a light release liner 20 releasably adhered to the adhesive 18 on the opposite side of the heavy release liner 12. The heavy release liner 12 is a two-layer peelable structure including a conformable film 22 and a rigid liner 24 that may also serve as a rigid-frame carrier 26 for the conformable film 22. The rigid-frame carrier 26 is attached to and covers at least a portion of the conformable film 22. The rigid-frame carrier 26 is formed of a material that is substantially more rigid than the conformable film 22 to provide rigidity to the delivery system 10, particularly after removal of the light release liner 20. The rigid-frame carrier 26 may be permanently or releasably attached to the conformable film 22. In the embodiment shown in Figures 1A, 1B, 1C, and 1D, the rigid frame carrier 26 does not extend into the adhesive area, allowing the adhesive 18 to have maximum ability to conform to the surface.

[0010] In one embodiment, the heavy release liner 12 comprises a thin, stretchable, conformable film 22 having a surface treated with a release coating and a rigid frame carrier 26. In one embodiment, the release coating can include, but is not limited to, silicone, fluoropolymer, or hydrophobic alkyl acrylate. If the rigid liner 24 supporting the conformable film 22 is also a rigid frame carrier 26 (as shown in FIG. 5 ), the bond between the rigid frame carrier 26 and the conformable film 22 is less than the bond between the adhesive 18 and both the heavy release liner 12 and the light release liner 20. The bond between the rigid frame carrier 26 and the conformable film 22 is equal to or less than the bond between the adhesive 18 and the light release liner 20. If the rigid frame carrier 26 is different from the rigid liner 24, the rigid liner 24 may be removed, and the rigid frame carrier 26 is bonded to the thin conformable film 22 during the conversion process to support the adhesive portion during the optical / display surface lamination. In one embodiment, the rigid frame carrier 26 can extend beyond the size and shape of the adhesive 18 to provide support and approximation for the adhesive 18 on the forming surface before lamination occurs under vacuum. In one embodiment, the heavy release liner 12 can also include at least one frame tab. The frame tab can be used to remove the thin conformable film 22 from the adhesive after application.

[0011] In one embodiment, the rigid frame carrier 26 includes a window 28 around the adhesive 18 so that the entire conformable film 22 that contacts the adhesive 18 is free to conform to the surface unobstructed during the lamination process. In another embodiment, the present invention also provides the advantage of strategically positioning the rigid frame carrier 26 on the conformable film 22 behind specific areas of the adhesive 18 to control distortion of the conformable film 22 and adhesive 18 as desired. Controlling distortion can reduce optical defects.

[0012] FIGS. 2 and 3 show bottom views of second and third embodiments 10a and 10b of adhesive delivery systems according to the present invention. Each of the second and third embodiments of the adhesive delivery system includes various embodiments of rigid frame carriers 26a, 26b. In certain cases, some degree of control over the adhesive 18 is desired to prevent it from freely deforming along with the conformable film 22. In these cases, the rigid frame carrier 26 may extend into the adhesive area to reduce and / or control the amount of stretch in desired areas, such as corners. In the second embodiment 10a shown in FIG. 2, the rigid frame carrier 26a includes a window 28a proximate the center of the adhesive 18 and an outer frame 26a proximate the periphery of the adhesive 18 to provide support for the adhesive 18. In the third embodiment 10b shown in FIG. 3, an inner frame 26b is used in areas of the adhesive 18 that do not require as much conformability. In this embodiment, the rigid frame carrier 26b includes protrusions 30 proximate the center of the adhesive 18 and extending toward the edges of the adhesive 18 to maintain the shape of the adhesive 18.

[0013] Figure 4 also shows a bottom view of a fourth embodiment 10c of the adhesive delivery system of the present invention. In the fourth embodiment 10c shown in Figure 4, the adhesive delivery system does not include a rigid frame carrier. In this case, the conformable film 22c is either rigid enough to provide structure to the adhesive delivery system or is completely laminated by a removable rigid carrier.

[0014] The adhesive delivery system 10 of the present invention is useful in conjunction with any conformable film 22 having an adhesive coating 18 thereon. In one embodiment, the adhesive 18 may have a heavy bond to the conformable film 22 and a light bond to another optical film, such as an OLED display, which can aid in a 3D molding or lamination process in which the conformable film 22 is adhered to the OLED and the adhesive / conformable film substrate is subsequently removed.

[0015] The light release liner 20 suitable for use in the adhesive delivery system 10 of the present invention can be made of materials including, but not limited to, polyester, polyethylene, polyurethane, polypropylene, or composites thereof. In one embodiment, the light release liner is coated with a release agent, such as a fluorochemical or silicone. For example, U.S. Patent No. 4,472,480, incorporated herein by reference, describes a low surface energy perfluorochemical liner. In one embodiment, the light release liner 20 can include, but is not limited to, polyester and polyolefin films coated with a silicone release material. Examples of commercially available silicone-coated release liners include, but are not limited to, RF02N liner available from SKC Haas (Korea), LN75 liner available from Nan Ya Plastics Corp. (Taiwan), and those sold by Loparex, located in Cary, North Carolina.

[0016] The conformable film 22 of the present invention has a true stress / strain gradient of no more than about 60 MPa, particularly no more than about 40 MPa, and more particularly no more than about 20 MPa, between 0 and 100% true strain, and no appreciable plastic (or permanent) deformation. This gradient is similar to Young's modulus of an elastic material, which can be defined as E = σ / ε, where E is Young's modulus, σ is the uniaxial engineering stress or force per unit fixed area, and ε is the uniaxial engineering strain, or proportional deformation (change in length divided by the original length). For large deformations, engineering strain does not accurately describe the deformation state, and true strain is then defined. True strain is the integral of the change in length divided by the length integrated from the original part length, which simplifies to the natural logarithm of the engineering strain in one-unit increments. For small strains (<1%), engineering strain is similar to true strain. For 3D laminates, true strain can exceed approximately 50%. True stress is defined like engineering stress, except the domain is no longer fixed. Because the gradient itself may not be constant, gradient limits are defined for the compliant material. Both E and σ have units of pressure, while ε is dimensionless. For a given amount of percent true strain on a compliant film, the true stress should not exceed the value limited by the gradient (e.g., 100% true strain should not exceed approximately 40 MPa).

[0017] The conformable film 22 is formed from a material that has the desired properties of resiliency and transparency of a release liner. In one embodiment, the conformable film 22 is a translucent or transparent polymer film. In one embodiment, the conformable film 22 can include, but is not limited to, polyurethane, polyethylene, polypropylene, polyvinyl chloride, polyacrylate, and combinations thereof.

[0018] In one embodiment, the conformable film 22 of the present invention includes a low-adhesion coating or surface on the adhesive-contacting side. The low-adhesion coating can be applied by applying a release coating or by adding a release additive to the conformable film resin before it is cast or extruded as a thin film. In one embodiment, the low-adhesion coating on the adhesive-facing side is compatible with both adhesive and rigid frame carrier bonding methods. If a low-adhesion coating is present on the opposite side, the adhesive is compatible with rigid frame carrier bonding methods.

[0019] The primary consideration in selecting any low adhesion coating or treatment according to the present invention is their release characteristics and their compatibility in the bond between the rigid frame carrier 26 and the conformable film 22, and between the adhesive 18 and the conformable film 22.

[0020] Rigid frame carriers 26 suitable for use in the adhesive delivery system 10 of the present invention can be made of materials including, but not limited to, polyurethane, polyester, polyethylene, polypropylene, or composites thereof. In one embodiment, the rigid frame carrier is coated with a release agent, such as a fluorochemical or silicone. For example, U.S. Pat. No. 4,472,480, incorporated herein by reference, describes a low-surface-energy perfluorochemical liner. In one embodiment, the rigid frame carrier 26 is coated with a low-adhesion adhesive layer. In this manner, the frame carrier can be bonded to a flexible, conformable liner to provide handling support during coating and lamination processes. In one embodiment, the rigid frame carrier can include, but is not limited to, polyurethane film, polyolefin film, and even paper. Examples of commercially available silicone-coated release liners include, but are not limited to, RF02N liner available from SKC Haas (Korea), LN75 liner available from Nan Ya Plastics Corp. (Taiwan), and those sold by Loparex, located in Cary, North Carolina.

[0021] In one embodiment, the material used to provide the rigid frame carrier 26 for the delivery system 10 is substantially stiffer than the conformable film 22 to prevent the conformable film 22 from wrinkling and to control undesired distortion of the adhesive 18 during application. The material used for the rigid frame carrier 26 may have a controlled bond to the conformable film 22. In one embodiment, the rigid frame carrier material 26 may be adhesive coated to create a bond to the conformable film 22. In another embodiment, the rigid frame carrier material 26 may also be bonded to the conformable film 22 by extruding a conformable film resin onto the rigid frame carrier material. In yet another embodiment, the rigid frame carrier material 26 may also be heat-sealable to the conformable film, with or without a low-adhesion coating, for purposes of manufacturing the adhesive delivery system 10. Generally, materials for the rigid frame carrier 26 can include, but are not limited to, polyester film, polycarbonate film, poly(methyl) methacrylate film, acrylonitrile butadiene styrene film, polypropylene film, polyurethane film, polyethylene terephthalate film, polyoxymethylene film, and combinations thereof.

[0022] Other combinations of release liners and adhesives are contemplated for use with embodiments according to the present invention. Those skilled in the art will be familiar with the process of testing new adhesives against different liners or new liners against different adhesives to arrive at the desired quality combination in the final product. Considerations related to the selection of silicone release liners can be found in Chapter 18 of "Handbook of Pressure Sensitive Adhesive Technology," Van Nostrand-Reinhold, 1982, pp. 384-403. U.S. Patent No. 4,472,480 also describes considerations related to the selection of perfluoropolyether release liners.

[0023] Release liners are available from a variety of manufacturers in a wide variety of proprietary formulations, and one skilled in the art would typically test them under simulated use conditions with a selected adhesive to arrive at a product with the desired release properties.

[0024] In one embodiment, adhesive 18 is an optically clear transfer adhesive that has high flow / creep at temperatures as high as about 65°C, low initial tack at room temperature, and sufficient adhesive properties for the display electronics and automotive industries. As used herein, the term "optically clear" refers to a material that, upon curing, has a haze of less than about 6%, particularly less than about 4%, and more particularly less than about 2%, a luminous transmittance of greater than about 88%, particularly greater than about 89%, and more particularly greater than about 90%, and an optical clarity of greater than about 98%, particularly greater than about 99%, and more particularly greater than about 99.5%. Typically, clarity, haze, and transmittance are measured on a structure in which the adhesive is held between two optical films, such as poly(ethylene terephthalate) (PET). Measurements are then taken on the entire structure, including the adhesive and substrate. Both haze and luminous transmittance can be measured, for example, using ASTM-D 1003-92. Optical measurements of transmittance, haze, and optical clarity can be performed, for example, using a BYK Gardner haze-gard plus 4725 instrument (Geretsried, Germany). The BYK instrument uses an illuminant "C" source and measures all light across its spectral range to calculate the transmittance value. Haze is the percentage of transmitted light that deviates from the incident beam by more than 2.5°. Optical clarity is evaluated at angles less than 2.5°. Typically, PCOCA is visually bubble-free.

[0025] Adhesive 18 can achieve high flow / creep at temperatures as high as approximately 65°C, low initial tack at room temperature, and sufficient adhesive properties for the display electronics and automotive industries. Adhesive 18 can be activated to achieve these properties by any method known to those skilled in the art. In one embodiment, adhesive 18 is a pressure-sensitive adhesive (PSA). PSAs can have lower tack, stronger molecular interactions (e.g., hydrogen bonding), and a high modulus at room temperature. In one embodiment, adhesive 18 is a heat-activated adhesive. In one embodiment, adhesive 18 behaves like a film (e.g., a plastic sheet) upon lamination and UV exposure, becoming viscoelastic and pressure-sensitive. In one embodiment, adhesive 18 is a chemically activated adhesive containing an additive that reacts with the adhesive, and as the reaction occurs, it builds up a bond very slowly. In one embodiment, adhesive 18 can include silicone on the surface of adhesive 18. The presence of silicone reduces initial adhesion, allowing the adhesive to be reworked (i.e., peeled) if there are stacking faults. Over time, the silicone migrates into the bulk of the adhesive, thus becoming tacky to the glass and providing greater adhesion to the glass. In one embodiment, adhesive 18 may be a tacky pressure-sensitive layer, but with a structure embodied to achieve repositionability and sliding properties. In one embodiment, adhesive 18 may be a tacky pressure-sensitive adhesive, but may have a non-tacky domain to aid in sliding or repositionability. The non-tacky domain may have a similar refractive index to the adhesive layer. The non-tacky domain may be a heat-activated adhesive formulation.

[0026] In one embodiment, the lamination temperature of adhesive 18 is from about 40°C to about 150°C, specifically from about 40°C to about 100°C, more specifically from about 50°C to about 80°C, and most specifically about 65°C.

[0027] Creep is a measure of how much adhesive 18 deforms when a given pressure or stress is applied. It would be expected that the higher the creep strain percentage, the more likely the adhesive will "flow" into a 3D shape when lamination pressure is applied. In one embodiment, adhesive 18 has a creep strain percentage of about 0 to about 100%, specifically about 2 to about 75%, and more specifically about 2 to about 50% at about 25°C. In one embodiment, adhesive 18 has a creep strain percentage of about 65 to about 800%, specifically about 85 to about 600%, and more specifically about 100 to about 500% at about 65°C.

[0028] In one embodiment, adhesive 18 has a glass transition temperature (Tg) of about -20°C to about 150°C, specifically about -15°C to about 100°C, and more specifically about -5°C to about 85°C.

[0029] Storage modulus is a measure of the elastic properties of adhesive 18. The higher the value, the more film-like the adhesive is, the more likely it is to have low tack and may have better slip. In one embodiment, adhesive 18 has a storage modulus at about 25°C of about 1E+4 to about 1E+9 Pa, specifically about 1E+5 to about 1E+8 Pa, and more specifically about 5E+5 to about 5E+7 Pa. In one embodiment, adhesive 18 has a storage modulus at about 65°C of about 1E+2 to about 1E+6 Pa, specifically about 1E+3 to about 1E+6 Pa, and more specifically about 1E+4 to 1E+6 Pa.

[0030] The loss modulus is a measure of the viscosity characteristics of adhesive 18. The higher the loss modulus, the more the adhesive behaves like a liquid. In one embodiment, adhesive 18 has a loss modulus at about 25°C of about 1E+3 to about 1E+9 Pa, specifically about 1E+4 to about 1E+8 Pa, and more specifically about 1E+5 to about 5E+7 Pa. In one embodiment, adhesive 18 has a storage modulus at about 65°C of about 1E+3 to about 5E+6 Pa, specifically about 1E+4 to about 1E+6 Pa, and more specifically about 1E+4 to about 1E+5 Pa.

[0031] The tan δ of adhesive 18 is the loss modulus divided by the storage modulus. Tan δ can help describe the "flow" of an adhesive. A higher tan δ generally means higher flow, with more "liquid-like" properties. In one embodiment, the adhesive has a tan δ of about 0.01 to about 2.5, specifically about 0.1 to 2.2, and more specifically about 0.4 to 1.5, at about 25°C. In one embodiment, the adhesive has a tan δ of about 0.1 to about 3, specifically about 0.25 to 3, and more specifically about 0.5 to 2.5, at about 65°C.

[0032] The adhesive 18 of the present invention, when cured, also has a peel adhesion strength of at least about 100 g / cm, specifically at least about 500 g / cm, and more specifically at least about 1000 g / cm, based on ASTM 3330. If the peel adhesion strength of the adhesive 18 is too low, the adhesive 18 may fail and the article containing it may fall apart (i.e., delaminate). Adhesives can fail in a variety of ways.

[0033] In one embodiment, the adhesive 18 is imparted with a microstructured pattern to prevent wetting on the substrate at room temperature. At elevated temperatures, the adhesive will wet out. The microstructure can function to promote air bleed during wetting. The microstructure can be imparted to the adhesive 18 either by coating directly onto a structured backing or by coating and then transferring to a structured backing. This structured backing acts as both a light and heavy release liner for the transfer adhesive. The heavy release liner will conform to the shape of the surface being covered to reduce buckling of the liner and adhesive during lamination.

[0034] In one embodiment, adhesive 18 is a multi-layer composite. The multi-layer structure includes at least two layers of adhesive with different properties. For example, a thin, less tacky adhesive skin layer and a PSA core layer. The less tacky adhesive layer provides "slip" ability during the lamination process, while the thick PSA core can provide efficient flow during the lamination process.

[0035] The delivery system 10 of the present invention includes a release on both sides of the conformable film 22, including a release with adhesive 18 and a release with rigid frame carrier 26. Alternatively, in some embodiments, the rigid frame carrier 26 is applied to the conformable film 22 as part of the die-cutting process, as opposed to using a rigid liner 24 as the rigid frame carrier substrate 26. Bonding the rigid frame carrier 26 during the conversion process creates a strong bond, which has a different set of requirements than bonding when the conformable film 22 is extruded onto the rigid frame carrier 26.

[0036] Examples of combinations that provide suitable carrier binding are provided in the examples below, although it is contemplated that many other combinations will also meet the requirements of the apparatus and methods according to the present invention.

[0037] As discussed above, the adhesive delivery system 10 includes a conformable film 22 having a controlled release surface on the top surface of the conformable film 22 and a controlled release surface on the bottom surface of the conformable film 22, an adhesive 18 adhered to the top surface of the conformable film 22, a rigid-frame carrier 26 adhered to either the top or bottom surface of the conformable film 22, and a light liner 20 attached to the exposed surface of the adhesive 18. In one embodiment, the rigid-frame carrier 26 is attached to the conformable film 22 with an extrusion melt bond or a heat-seal bond. Optionally, a window 28 can be cut from the rigid-frame carrier 26 to create a window that exposes the frame and a portion of the surface of the conformable film 22. The rigid-frame carrier 26 provides rigidity to the conformable film 22 after the light liner 20 is removed from the delivery system 10. As mentioned above, a low-adhesion coating between the liner and the adhesive 18 is compatible with the bond between the rigid-frame carrier 26 and the conformable film 22. Various methods of manufacturing the adhesive delivery system 10 of the present invention are described below.

[0038] 5A-5H illustrate one embodiment for manufacturing the adhesive delivery system 10 of the present invention. In this embodiment, a conformable film 22 is first fabricated on a rigid liner 24, which also becomes a rigid frame carrier 26. The adhesive 18 is then coated between the light release liner 20 and the conformable film 22. In one embodiment, the differential peel strength of the adhesive 18 between the light release liner 20 and the heavy release liner 12 is about 5 to about 10 g / inch. Specifically, the release force of the heavy release liner 12 is about 1.5 times greater than the release force of the light release liner 20. In one embodiment, the differential peel strength between the conformable film 22 and the rigid liner 24 is about 10 to about 20 g / inch. In one embodiment, the differential peel strength between the heavy release liner 12 and the adhesive 18 is about 15 to about 25 g / inch. The light release liner 20 is then removed, and the adhesive 18 is cut as needed. Any adhesive waste is then stripped away. In one method of manufacturing the delivery system 10, the caliper and modulus of the conformable film provide enough structure to strip the adhesive waste from the conformable film 22 without breaking the somewhat weak bond between the rigid liner 24 and the conformable film 22. A light release liner 20 is laminated to the adhesive 18 to form the adhesive delivery system 10. The rigid carrier frame 26 can be severed from the rigid liner 24 as needed, with any waste removed. In this embodiment, the bond between the rigid frame carrier 26 and the conformable film 22 is less than the bond between the adhesive 18 and the conformable film 22. This difference ensures that the adhesive 18 remains attached to the conformable film 22 when the rigid frame carrier waste is removed from the delivery system 10. In one embodiment, the bond between the adhesive 18 and the conformable film 22 is not significantly greater than the bond between the conformable film 22 and the rigid frame carrier 26, so that the bond between the rigid frame carrier 26 and the conformable film 22 is not broken when the adhesive waste is stripped. In this embodiment, conformable film 22 is attached to and supported by rigid liner 24 during part fabrication.

[0039] 6A-6H illustrate another embodiment of manufacturing the adhesive delivery system 10 of the present invention. In this embodiment, a conformable film 22 is fabricated first. Then, adhesive 18 is coated between the conformable film 22 and a light release liner 20. A rigid frame carrier 26 is then laminated to the conformable film 22. The light release liner 20 is removed, and the adhesive 18 is cut as needed. Similar to the embodiment shown in FIGS. 5A-5H, the adhesive waste is then stripped, and the light release liner 20 is laminated to the adhesive 18 to form the adhesive delivery system 10. In this embodiment, the conformable film 22 is not supported by a rigid material that becomes the rigid frame carrier 26. Rather, a frame is added during manufacturing.

[0040] 7A-7L illustrate yet another embodiment for manufacturing the adhesive delivery system 10 of the present invention. The embodiment illustrated in FIGS. 7A-7L is similar to the embodiment illustrated in FIG. 5, except that a temporary support web 34 is laminated to the release side of the extruded conformable film 22 for support so that the backing of the extruded conformable film 22 can be removed (rather than becoming part of the rigid frame carrier 26 as in the embodiment of FIGS. 5A-5H) and the desired frame material can be laminated in its place. In this embodiment, the conformable film 22 is extruded onto the rigid liner 24, and a release layer 32 is coated onto the conformable film 22. To convert, the temporary carrier 34 is laminated to the release side of the conformable film 22 for support, and the rigid liner 24 is stripped from the conformable film 22. The rigid frame carrier material 26 is then die-cut as needed, and waste material is removed. The rigid frame carrier 26 is then laminated to the conformable film 22. The adhesive 18 is coated between the light release liner 20. One release liner 20 is removed from the adhesive 18, the adhesive 18 is die cut, and the waste is stripped. Finally, the die cut adhesive is laminated to the release side of a conformable film 22.

[0041] 8A-8O disclose yet another embodiment for manufacturing the adhesive delivery system 10 of the present invention. The embodiment of FIGS. 8A-8O maintains both the adhesive 18 and the conformable film 22 fully supported by the rigid material until they are laminated together. Furthermore, the rigid material (light release liner 20 and rigid liner 24) can be easily removed with low peel forces, reducing the risk of deforming or damaging the conformable film / optical film laminate. The first few steps of the embodiment of FIGS. 8A-8O are the same as those of the embodiment of FIGS. 7A-7L. However, the conversion step is different. Rather than adhering the carrier frame 26 to the bottom of the conformable film 22, the carrier frame 26 is adhered to the release side. In this way, the rigid liner 24 can remain on the die-cut portion to support the conformable film 22 until removal is desired. By using the supporting rigid liner 24, a temporary carrier during manufacturing is not required, as is the case with FIGS. 7A-7L.

[0042] 8A-8O continue to show how the adhesive delivery system 10 is secured to the laminator to apply the adhesive 18 onto a forming surface. The rigid liner 24 is removed, and the rigid carrier frame 26 is clamped to the periphery of the adhesive delivery system 10 with clamps 38. The light release liner 20 is then removed, and the adhesive 18 is conformed to a puck 36 that embodies the shape of the 3D part. The adhesive 18 is then laminated to a forming surface 40, which is under a vacuum to prevent air from being trapped between the laminates. Once laminated, the part is released to atmospheric pressure, and then the puck 36, clamps 38, and conformable film 22 are removed, and the adhesive 18 is adhered to the forming surface 40.

[0043] 9A-9C show a flow chart of adhesive 18 being laminated to a forming surface 40 according to one embodiment of the present invention. This embodiment is similar to the method shown in FIGS. 8A-8O, except that in this embodiment, frame 26 is assembled to the side of conformable film 22 opposite adhesive 18. The adhesive portion is first placed in a lamination fixture and light release liner 20 is removed. Puck 36 is pressed into adhesive 18 such that it assumes the shape of puck 36 when pressed against forming surface 40 while in a vacuum chamber.

[0044] In practice, the conformable film 22 and rigid frame carrier 26 are necessary to conform the adhesive 18 to the molding surface 40 and support the adhesive 18 for lamination. In one embodiment, the adhesive 18 and conformable film 22 are pressed onto the surface to be mated with the pack 36. If the adhesive 18 includes a textured surface, the microstructures on the adhesive 18 promote sliding for alignment during lamination and air bleeding.

[0045] Various methods can be used to optically bond the adhesive 18 of the delivery system 10 to the molding surface 40. One method uses lamination equipment operating under vacuum to eliminate trapped air. FIGS. 10 and 11 show top and side views, respectively, of one embodiment of a modeling setup for applying the adhesive delivery system 10 of the present invention. In the embodiment shown in FIGS. 10 and 11, the adhesive 18 is stretched on a puck 36 before lamination. The equipment includes a clamping mechanism 38 for holding the edges of the adhesive delivery system 10 and conforming to the shape of the surface, and a compliant puck 36 for pressing the adhesive 18 into or onto a shape to improve wetting of the adhesive 18. The adhesive 18 is then clamped during the lamination process to stretch the adhesive 18 on the puck 36. In practice, the adhesive 18 is held under tension during lamination so that no compression forces are present during the process. Modeling indicates that the adhesive 18 needs to be under tension everywhere during lamination; compression forces should not be present. If compression forces are present, the adhesive 18 will buckle during lamination, resulting in insufficient wetting. The adhesive 18 must be constrained on all four sides or buckling will occur on the unconstrained sides, resulting in a poor fit to the pack 36 .

[0046] In one embodiment, the puck 36 is formed of silicone. The soft silicone puck is compressed during film tensioning prior to lamination, resulting in displacement. This provides pre-edge contact of the adhesive 18 and prevents wetting at the corners of the molding surface 40. As shown in FIG. 12, the maximum displacement that occurs at the corners of the puck 36 is generally a function of the puck hardness.

[0047] In some embodiments, the resulting laminate can be an optical element or can be used to prepare an optical element. As used herein, the term "optical element" refers to an article having an optical effect or optical application. Optical elements can be used, for example, in electronic displays, architectural applications, transportation applications, projection applications, optical communication applications, and graphic applications. Suitable optical elements include, but are not limited to, glazing (e.g., windows and windshields), screens or displays, cathode ray tubes, and reflectors.

[0048] Exemplary optically transparent substrates include, but are not limited to, a display panel such as a liquid crystal display, an OLED display, a touch panel, or a cathode ray tube, a window or glazing, an optical component such as a reflector, a polarizer, a diffraction grating, a mirror or a cover lens, or another film such as a decorative film or another optical film.

[0049] Representative examples of optically transparent substrates include glass and polymer substrates, including polycarbonate, polyester (e.g., polyethylene terephthalate and polyethylene naphthalate), polyurethane, poly(meth)acrylate (e.g., polymethyl methacrylate), polyvinyl alcohol, polyolefins such as polyethylene, polypropylene, and those containing cellulose triacetate. Typically, the cover lens can be made of glass, polymethyl methacrylate, or polycarbonate.

[0050] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. The following are exemplary embodiments. [Item 1] a conformable film having a top surface and a bottom surface; an adhesive releasably coated on at least a portion of the top surface of the conformable film; a light liner adhered to the adhesive side opposite the conformable film; 1. An adhesive delivery system comprising: [Item 2] Item 10. The adhesive delivery system of item 1, further comprising a rigid frame carrier attached to the conformable film. [Item 3] 3. The adhesive delivery system of item 2, wherein the rigid frame carrier includes a window. [Item 4] 4. The adhesive delivery system of claim 3, wherein the window of the rigid frame carrier is positioned proximate to the center of the adhesive and the rigid frame carrier is positioned proximate to the periphery of the conformable film. [Item 5] 3. The adhesive delivery system of claim 2, wherein the rigid frame carrier is formed of a material that is more rigid than the conformable film. [Item 6] 3. The adhesive delivery system of claim 2, wherein the bond between the rigid frame carrier and the conformable film allows the adhesive to be removed from the conformable film without disrupting the bond between the conformable liner and the rigid frame carrier. [Item 7] 2. The adhesive delivery system of claim 1, wherein the conformable film is selected from the group consisting of polyurethane, polyethylene, polypropylene, polyvinyl chloride, polyacrylate, and combinations thereof. [Item 8] 2. The adhesive delivery system of claim 1, wherein the adhesive comprises a multi-layer composite material. [Item 9] 2. The adhesive delivery system of claim 1, wherein the adhesive is heat activated. [Item 10] 2. The adhesive delivery system of claim 1, wherein the adhesive is optically clear. [Item 11] Item 10. The adhesive delivery system of item 1, wherein the adhesive comprises a microstructure. [Item 12] a conformable film having a top surface and a bottom surface; an adhesive coated on at least a portion of the top surface of the conformable film; a liner releasably adhered to the adhesive side opposite the conformable film; a carrier firmly or releasably attached to the conformable film, the carrier further being formed of a material that is substantially more rigid than the conformable film. [Item 13] 13. The adhesive delivery system of claim 12, wherein the conformable film is selected from the group consisting of polyurethane, polyethylene, polypropylene, polyvinyl chloride, polyacrylate, and combinations thereof. [Item 14] 13. The adhesive delivery system of claim 12, wherein the bond between the carrier and the conformable film is stronger than the bond between the adhesive and the conformable film. [Item 15] Item 13. The adhesive delivery system of item 12, wherein the adhesive is heat activated. [Item 16] 13. The adhesive delivery system of claim 12, wherein the adhesive is optically clear. [Item 17] Item 13. The adhesive delivery system of item 12, wherein the adhesive comprises a microstructure.

Claims

1. a conformable film having a top surface and a bottom surface; an adhesive releasably coated onto at least a portion of the top surface of the conformable film; a light liner adhered over the adhesive and opposite the conformable film; a rigid frame carrier attached to the conformable film; Equipped with the peel force between the light liner and the adhesive is less than the peel force between the conformable film and the adhesive; The rigid frame carrier has an outer frame and a window inside the outer frame exposing a portion of the conformable film surface including a center thereof. Adhesive delivery system.

2. The adhesive delivery system of claim 1 , wherein the rigid frame carrier is formed of a material that is more rigid than the conformable film.

3. 10. The adhesive delivery system of claim 1, wherein the bond between the rigid frame carrier and the conformable film allows the adhesive to be removed from the conformable film without destroying the bond between the conformable film and the rigid frame carrier.

4. The adhesive delivery system of claim 1 , wherein the conformable film is selected from the group consisting of polyurethane, polyethylene, polypropylene, polyvinyl chloride, polyacrylate, and combinations thereof.

5. The adhesive delivery system of claim 1 , wherein the adhesive comprises a multi-layer composite material.

6. The adhesive delivery system of claim 1 , wherein the adhesive is optically clear.

7. The adhesive delivery system of claim 1 , wherein the adhesive comprises a microstructured pattern on a surface thereof.

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