Film with structured adhesive and structured liner and method of making the same

Abstract

To provide films that are particularly suitable to provide adhesive films with structured adhesives with readily recyclable liners.SOLUTION: A film 100 comprises: a substrate 110 with a first major surface and a second major surface; an adhesive layer 120 disposed on the second major surface; and a release liner 140 disposed on the adhesive layer opposite from the substrate; wherein the adhesive layer has a first structure pattern 122; wherein the release liner has a second structure pattern 142; and wherein the first structure pattern and the second structure pattern are not the inverse of or the same as each other.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] Films with a structured adhesive layer can exhibit desirable qualities such as air evacuation or repositionability. A liner is attached to the other side of the adhesive to allow for storage and handling of the film before removal of the liner, as well as adhesion of the film to a surface. Summary of the Invention

[0002] In one aspect, the present disclosure relates to a film. The film includes a substrate having a first major surface and a second major surface, an adhesive layer disposed on the second major surface, and a release liner disposed on the adhesive layer on the opposite side to the substrate. The adhesive layer has a first structural pattern, and the release liner has a second structural pattern. The first structural pattern and the second structural pattern are not the inverse of each other, and are not the same as each other.

[0003] In another aspect, the present disclosure relates to a film. The film includes a substrate having a first major surface and a second major surface, an adhesive layer disposed on the second major surface, and a release liner disposed on the opposite side of the adhesive layer from the substrate. The adhesive layer has a first structural pattern, and the release liner has a second structural pattern. Due to the second structural pattern, there is a gap between the adhesive layer and a portion of the release liner.

[0004] In yet another aspect, the disclosure relates to a method. The method includes providing a substrate having a first major surface and a second major surface, applying an adhesive layer on the second major surface, and embossing the adhesive layer with a first liner to form a structured adhesive layer having a first structural pattern. The method further includes removing the first liner and attaching a second liner having a second structural pattern to the structured adhesive layer. The second structural pattern is neither the inverse of the first structural pattern nor the same as the first structural pattern. [Brief description of the drawings]

[0005] [Figure 1]FIG. 2 is a schematic cross-sectional side view of a film having a structured adhesive and a structured liner. [Diagram 2] FIG. 2 is a schematic cross-sectional side view of a film having a structured adhesive formed by an intermediate structured liner. [Diagram 3] FIG. 2 is a schematic cross-sectional side view of a film having a structured adhesive formed by a structured continuous belt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Adhesive films, such as graphic or "wrap" films used to customize the appearance of buildings, interior environments, or vehicles, are typically shipped with a liner attached to the adhesive side. The liner is selected to prevent the film from adhering to itself or to any surface other than the desired application substrate. Since the film is often recessed to be permanently or semi-permanently applied to the substrate to which it is applied (i.e., not to be repositioned later), the liner plays an important role by preventing unintentional adhesion. The liner is often carefully designed, and the material that comes into contact with the adhesive is specifically selected to facilitate easy release (i.e., low peel force required). Often, a silicone layer is provided at the interface between the adhesive and the liner to provide good release properties.

[0007] Certain films include structured adhesives, where microelements may provide application features such as air evacuation and slidability (e.g., IJ180Cv3 from 3M Company with Comply™ and Controltac™ adhesives). In some cases, these structured features are formed by mating a structured liner to a substantially featureless adhesive layer. The features are embossed, and the adhesive receives a structured pattern that is the inverse of the structured liner. For example, a structured liner with ridges would be mated to create channels in the adhesive layer. This structured interface provides more contact surface area between the liner and adhesive, and therefore the design is more dependent on the selection of liner material for ultimate acceptable release.

[0008] Since the liner is removed at or very close to the time and place of final application, the removed liner typically remains and is discarded by the customer. Since the liner covers the entire film, the waste stream can be large; that is, at least the footprint of the area of ​​the film used must be discarded. In addition, to achieve acceptable release properties as described above, materials such as silicone or even polytetrafluoroethylene are used. These materials are not commercially recyclable (at least currently) and therefore are incinerated or used in landfills.

[0009] Previously, commercially available recyclable liners were thought not to be technically possible on structured adhesives due to the high surface energy of recyclable plastics (relative to other release materials). Such constructions were assumed to be unsuitable because they would not release from the adhesive or would require excessive force to release from the release liner.

[0010] Surprisingly, it has been found that acceptable release properties can be achieved by providing structure to the adhesive layer with a release liner, removing the release liner, and attaching a second liner (which may be recyclable) with a different structured surface. The structured surface of the second liner limits the surface area of ​​contact between the liner and the adhesive, and therefore the peel force required for removal remains low.

[0011] Although certain embodiments of the described process and related articles may require the use of a first liner and a second liner, there may be realizable advantages to using the techniques highlighted herein. First, the manufacturing site or factory may be able to take advantage of special recycling programs that are not available to individual small customers. The liner removed at the manufacturing site may be reusable. In some embodiments, the first liner is replaced with an embossing roll or continuous belt, eliminating the requirement for two separate disposable liners.

[0012] 1 is a schematic cross-sectional side view of a film having a structured adhesive and a structured liner. The film 100 includes a film substrate 110, a structured adhesive layer 120 including a first structural pattern 122 including adhesive microelements 124, and a structured liner 140 including a second structural pattern 142 including liner microelements 144. Gaps 150 exist between the structured liner and the structured adhesive layer.

[0013] The film substrate 110 may be any suitable film substrate. In some embodiments, the film substrate 110 may be a vinyl (polyvinyl chloride) film substrate. In some embodiments, the film substrate 110 may be a thermoplastic polyurethane blended with cellulose acetate butyrate or cellulose acetate propionate. In some embodiments, the film substrate 110 may be a thermoplastic polyurethane blended with polyvinyl butyral. Any other polymer or blend of polymers may also be used. The film substrate 110 may be selected for its conformability, stretchability, or other physical properties. In some embodiments, the film substrate may be printable by either an inkjet printer, a latex printer, a solvent printer, or any other printer. The substrate itself may be printable, or the substrate may optionally have an ink-receiving layer on the printable surface. The film substrate 110 may be of any suitable thickness, with the thickness selected based on the desired flexibility, stretchability, conformability, handling, or other properties. A suitable thickness may be between 20 and 500 micrometers. In some embodiments, the film substrate 110 may be smooth and substantially feature-free, or in some embodiments, the film substrate 110 may have a surface texture, such as a matte appearance, in some embodiments, the film substrate 110 may be transparent, and in some embodiments, the film substrate 110 includes a pigment, dye, or other colorant (including white).

[0014] The structured adhesive layer 120 may be any suitable adhesive. The structured adhesive may be coated on or laminated to the film substrate 110. In some embodiments, the structured adhesive layer may have sufficient structure to maintain its shape (i.e., not flow) over a range of exposure temperatures and humidity. In some embodiments, the adhesive may be an acrylic adhesive. In some embodiments, the adhesive may be a pressure sensitive adhesive. In some embodiments, the adhesive may be fully or partially crosslinked. The structured layer may include a pigment, dye, or other colorant. The structured adhesive layer may be of any suitable thickness. In some embodiments, the thickness of the structured adhesive layer may be between 10 and 100 micrometers. In some embodiments, the structured adhesive layer 120 may include partially embedded microbeads made from materials such as glass, ceramic, or polymer resins, or aggregates thereof held together with a suitable binder material. In some embodiments, the microbeads may be index matched to the structured adhesive and / or may be transparent.

[0015] The structured adhesive layer 120 includes a first structured pattern 122 that includes adhesive microelements 124. The first structured pattern 122 may be any suitable or desired pattern. In FIG. 1, the pattern shown is regular, with each of the microelements 124 being the same size and spacing. However, this is not required and any regular, irregular (non-periodic, or even pseudo-random or random) pattern may be used, and in some embodiments, the size and shape of each of the adhesive microelements 124 may vary smoothly or in a step-like manner across one or more dimensions of the film. In some embodiments, the first structured pattern 122 is a one-dimensional pattern, meaning that the first structured pattern does not vary along more than one dimension (e.g., in the pattern shown in FIG. 1, the microelements are the same shape and size in the direction into and out of the page). Alternatively, the first structured pattern 122 may be a two-dimensional pattern, with features arranged, for example, in a matrix or grid. In some embodiments, the adhesive microelements 122 may be linear channels. In some embodiments, the adhesive microelements 122 may be curved channels. The cross-sectional shape of the adhesive microelements may be substantially rectangular (as shown in FIG. 1) or may have other suitable shapes, such as triangular or hemispherical. In some embodiments, the depth of the adhesive microelements may be 95% or less, or 90% or less, or 80% or less, or 70% or less, or 60% or less, or 50% or less, or 40% or less, or 30% or less, or 20% or less, or 10% or less of the thickness of the structured adhesive layer.

[0016] Structured liner 140 may be made from any suitable material by any suitable process. In some embodiments, structured liner 140 may be microreplicated (e.g., via a continuous casting and curing process), embossed, injection molded, or even additively manufactured (i.e., 3D printed). In some embodiments, structured liner 140 may be substantially formed from commercially recyclable materials. For example, structured liner 140 may be substantially formed from high density polyethylene, low density polyethylene, polyvinyl chloride, polystyrene, or polypropylene. In some embodiments, structured liner 140 may have a thermal conductivity of 35 mJ / m 2 (equivalent to dynes / cm) or less.

[0017] In some embodiments, the structured liner 140 does not include materials or additional layers or coatings that are not suitable for commercial recycling, hi some embodiments, the structured liner is marked with a resin identification code to aid in identification for recycling.

[0018] The structured liner 140 includes a second structured pattern 142 that includes liner microelements 144. Similar to the first structured pattern 122, the second structured pattern 142 may be any suitable pattern including any size or shape of microelements or combination of microelements. In some embodiments, as shown in FIG. 1, the second structured pattern 142 is regular, with each of the liner microelements being the same size and evenly spaced. Of course, any regular, irregular (non-periodic, pseudo-random, or random) pattern may be used. The size and shape of the liner microelements may vary (smoothly or stepwise) across one or more dimensions of the film. In some embodiments, the second structured pattern 142 is a one-dimensional pattern. In some embodiments, the second structured pattern 142 is a two-dimensional pattern. In some embodiments, the cross-sectional shape of the liner microelements 144 is substantially triangular or prismatic (as shown in FIG. 1). In some embodiments, the liner microelements 144 include extended tips (narrower second prisms at the apex of a base prism shape).

[0019] In addition, due to the shape of the second structural pattern, there are gaps between at least a portion of the structured liner 140 and the structured adhesive layer 220. The gaps 150 may contain air or any other atmospheric gas. The size and shape of the microelements, and therefore the general configuration of the second structural pattern 142, will depend on the application and the desired performance. It will be apparent to one skilled in the art that the pattern may be selected to create a desired surface contact area between the structured liner and the structured adhesive, resulting in a desired peel upon removal of the liner. More surface area contact generally results in a stronger bond between the liner and the adhesive.

[0020] It is important to note that the first structural pattern and the second structural pattern are neither the same nor the inverse of each other. At least one characteristic of the patterns should be different from each other. For example, the second structural pattern of the structured liner may be ridges and the first structural pattern of the structural adhesive may be channels, but they may have features of different sizes, pitches, or arrangements (i.e., the microelements may be offset along different axes). In this case, the first structural pattern and the second structural pattern are neither the same nor the inverse of each other. Of course, two or more characteristics may be different between the first structural pattern and the second structural pattern.

[0021] The particular selection of the shape and size of the structures, as well as the thickness and flowability of the adhesive, may help prevent the adhesive from completely wetting the surface structures, thereby reducing the effect that closely interlocking structures may have on peeling. For example, in some embodiments, the structures of the second structure pattern are shaped and sized such that the structure pattern displaces a larger volume per unit area between the support surface and the planar land area than the adhesive volume for the same unit area.

[0022] The film 100 may be provided in any suitable form, including a conversion sheet cut to size, or in some embodiments, in roll form. Subsequent processing, such as printing or overlamination, may be performed on the film in either form. In some embodiments, the film 100 is a large format graphic, having a longest dimension of at least 1 meter.

[0023] 2 is a schematic cross-sectional side view of a film having a structured adhesive formed by an intermediate structured liner. The film 200 includes a film substrate 210, a structured adhesive layer 220 including a first structural pattern 222 including adhesive microelements 224, and an intermediate liner 230 including a second structural pattern 232 including liner microelements 234.

[0024] Film substrate 110 and structured adhesive layer 120 correspond to film substrate 210 and structured adhesive layer 220. However, intermediate liner 230 is intended to provide structure to structured adhesive layer 220 without being permanently adhered to the adhesive layer. Thus, the intermediate liner is made from a suitable material such that peeling of intermediate liner 230 from structured adhesive layer 220 does not damage or distort the first structural pattern.

[0025] In some embodiments, the intermediate liner is a polymer coated with an elastomeric silicone, so that when the intermediate liner and the adhesive layer are joined, the silicone contacts the adhesive layer. In some embodiments, the intermediate liner is a polymer coated paper. In some embodiments, the intermediate liner includes a coating of polytetrafluoroethylene. In some embodiments, the intermediate liner includes a polyester block copolymer. The intermediate liner may be formed by any suitable method, such as microreplication, embossing, injection molding, or additive manufacturing. Multiple process steps may also be used, especially when, for example, a second material is coated onto the base film.

[0026] An intermediate liner is attached to the adhesive layer to provide structure to the structured adhesive layer. Thus, the first structural pattern of the adhesive is the inverse of the second structural pattern provided on the intermediate liner. In some embodiments, the intermediate liner also contains or carries microbeads. In some embodiments, the adhesive may be partially cured while attached to the intermediate liner.

[0027] The particular selection of the shape and size of the structures, as well as the thickness and flowability of the adhesive, can help prevent the adhesive from completely wetting the intermediate liner surface structures. For example, in some embodiments, the structures are shaped and sized such that they displace a larger volume per unit area between the support surface and the planar land area than the adhesive volume for the same unit area.

[0028] The intermediate liner is then removed from the film construction. The liner may be removed before or after the film is converted. That is, the liner may be separated in a continuous process or the process may be performed in batches. After removing the intermediate liner, a structured liner, such as structured liner 140 shown in FIG. 1, is laminated or attached to the exposed structured adhesive layer. In some embodiments, the structured liner has a higher surface energy than the intermediate liner.

[0029] FIG. 3 is a schematic cross-sectional side view of a film with structured adhesive formed by a structured continuous belt. The film includes a film substrate 310 and a structured adhesive layer 320 that includes a first structured pattern 322. The adhesive layer of the film is structured by a continuous belt 360 that has a second structured pattern 362 disposed on a roller 370. Similar to the intermediate liner described in connection with FIG. 2, a continuous belt is used to impart the first structured pattern 322 onto the structured adhesive layer 320. In a film line process, the substrate film and structured adhesive layer (film substrate 310 and structured adhesive layer 320 are only a portion of a continuous web of material) pass over a continuous belt that contacts the adhesive layer. An inverse of the second structured pattern 362 is provided on the structured adhesive layer as the first structured pattern 322. In some embodiments, the second structured pattern has structures that are shaped and sized such that the structured pattern displaces a volume per unit area between a support surface and a planar land area greater than the adhesive volume for the same unit area.

[0030] The belt and film should move at approximately the same speed in the machine direction so that the pattern can be accurately applied to the adhesive layer. The adhesive may be partially cured while in contact with the structured continuous belt.

[0031] The structured continuous belt is provided on at least one roller 370. In some embodiments, the structured continuous belt 360 is provided on two rollers. At least one of the rollers is powered to rotate the structured continuous belt at a desired speed. The structured continuous belt may be any suitable material and may be formed from any suitable process. For example, the structured belt may be or include a hard material coated with an elastomeric silicone.

[0032] In some embodiments, the use of a continuous belt provides the advantage of not having to apply and remove an intermediate liner. In some embodiments, the use of a continuous belt allows the liner change process to be efficiently integrated into a film manufacturing line without generating waste. As described in connection with the process shown in FIG. 2, a structured liner, such as the structured liner 140 shown in FIG. 1, is applied to the exposed structured adhesive layer. In some embodiments, the structured liner has a higher surface energy than the structured continuous belt.

[0033] Descriptions of elements in the figures should be understood to apply equally to corresponding elements in other figures unless otherwise indicated. The present invention should not be considered limited to the particular embodiments described above, as such embodiments have been described in detail to facilitate explanation of the various aspects of the invention. Rather, the present invention should be understood to encompass all aspects of the invention, including various modifications, equivalent processes, and alternative devices, included within the scope of the invention as defined by the appended claims and their equivalents. EXAMPLES

[0034] [Table 1]

[0035] Test Method Film Lamination: The paper liner of the 1080 white film was removed and the adhesive side of the 1080 white film was laminated to the structured side of the PE liner. The PE liner was then removed and the 1080 white film was manually laminated to the glass substrate using a hand roller weighing approximately 10 lbs.

[0036] Peel (liner peel force) test: Film samples laminated to a PE liner were cut into strips approximately 1 / 2'' wide and mounted at a 180 degree orientation on an I-MASS SP-2000 peel tester (Accord, Mass.). Peel force was measured at a rate of 12 inches / min.

[0037] Working Example Using the test method described above, the 1080 white film was laminated to a textured PE liner. After a dwell time of approximately 3 minutes, the film was removed from the textured liner (PE liner) and laminated to a smooth glass substrate in the same manner. The film applied easily and without air bubbles, indicating that air release channels were still present on the adhesive. The texture of the PE liner was visible through the film and could be visually observed while the 1080 white film was on the PE liner. However, once the 1080 white film was removed from the textured PE liner and laminated to the smooth substrate, the texture smoothed out and was no longer visually observable.

[0038] After a dwell time of about 3 minutes, the 1080 white film was manually removed from the glass substrate. The 1080 white film was removed cleanly from the glass substrate without leaving any residue, indicating that the 1080 white film retained its repositionable properties.

[0039] Peel force (liner release force) was measured using the peel tested as described above. Three samples were tested and the average peel force results are reported below in Table 1. These results represent generally acceptable values.

[0040]

Table 2

Claims

1. A substrate having a first major surface and a second major surface; an adhesive layer disposed on the second major surface; a release liner disposed on an opposite side of the adhesive layer from the substrate, the adhesive layer has a first structural pattern; the release liner has a second structural pattern; A film, wherein the first structured pattern and the second structured pattern are neither the inverse of each other nor the same as each other.

2. A substrate having a first major surface and a second major surface; an adhesive layer disposed on the second major surface; a release liner disposed on an opposite side of the adhesive layer from the substrate, the adhesive layer has a first structural pattern; the release liner has a second structural pattern; A film, wherein a gap exists between the adhesive layer and a portion of the release liner due to the second structural pattern.

3. 3. The film of claim 1 or 2, wherein the release liner is commercially recyclable.

4. The release liner has a resistance of 35 mJ / m ２ 3. The film of claim 1 or 2 formed from a polymer having a surface energy of:

5. 3. The film of claim 1 or 2, wherein the release liner is formed substantially from one of the group consisting of high density polyethylene, low density polyethylene, polyvinyl chloride, and polypropylene.

6. A roll of film comprising the film of claim 1 or 2.

7. The film of claim 1 or 2, wherein one or both of the release liner and the adhesive layer comprise beads.

8. The film of claim 7 , wherein the second structural pattern has a period, the period having a length equal to or greater than an average diameter of the beads.

9. The film of claim 1 or 2, wherein the first structure pattern and the second structure pattern have different periods.

10. The film of claim 1 or 2, wherein the adhesive layer comprises an acrylic adhesive.

11. The film of claim 1 or 2, wherein the first structural pattern is a channel and the second structural pattern is a prism.

12. The film of claim 1 or 2, wherein both the first structured pattern and the second structured pattern are one-dimensional patterns.

13. 3. The film of claim 1 or 2, wherein the second structure displaces a volume per unit area between the support surface of the release liner and the planar land area of ​​the release liner that is greater than the volume of the adhesive layer for the same unit area.

14. Providing a substrate having a first major surface and a second major surface; applying an adhesive layer onto the second major surface; embossing the adhesive layer with a first liner to form a structured adhesive layer having a first structural pattern; removing the first liner; and adhering a second liner having a second structural pattern to the structured adhesive layer, the second structural pattern being neither a reverse of the first structural pattern nor the same as the first structural pattern.

15. The method of claim 14 , wherein the first liner comprises silicone.

16. The method of claim 14, wherein the first liner is a belt.

17. The method of claim 14 , wherein the first liner and the second liner are different materials.

18. 15. The method of claim 14, wherein the second liner is formed essentially from one of the group consisting of high density polyethylene, low density polyethylene, polyvinyl chloride, and polypropylene.

19. The method of claim 14 , wherein the second liner is formed substantially from commercially recyclable materials.

20. The method of claim 14 further comprising winding the film into a roll.

21. The second liner essentially has a thermal conductivity of 35 mJ / m ２ 15. The method of claim 14, formed from a polymer having a surface energy of:

22. The method of claim 14 , wherein the second liner has a higher surface energy than the first liner.

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