EP4695073A1 - Multilayer polymer film, method, and articles suitable for thermoforming - Google Patents

Abstract

A method of making a thermoformed article is described comprising providing a multilayer film in a thermoforming apparatus, wherein the multilayer film comprises a) a first film comprising a thermoplastic structured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contact the peaks and fill the valleys of the thermoplastic structured surface of the first film. The method further comprises thermoforming the first film into an article at a thermoforming temperature while the second protective film is in contact with the thermoplastic structured surface of the first film. In typical embodiments, the method further comprising removing the second structured protective film from the thermoformed article after thermoforming. Also described is a thermoformed article, a method of (e.g. insert) injection molding, multilayer films articles, and structured protective films.

Description

MULTILAYER POLYMER FILM, METHOD, AND ARTICLES SUITABLE FOR THERMOFORMING

SUMMARY

In one embodiment, a method of making a thermoformed article is described comprising providing a multilayer film in a thermoforming apparatus, wherein the multilayer film comprises a) a first film comprising a thermoplastic stmctured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contact the peaks and fill the valleys of the thermoplastic structured surface of the first film. The method further comprises thermoforming the first film into an article at a thermoforming temperature while the second protective film is in contact with the thermoplastic stmctured surface of the first film. In typical embodiments, the method further comprising removing the second structured protective film from the thermoformed article after thermoforming.

In another embodiment, a thermoformed article is described comprising a) a thermoformed first film comprising a thermoplastic structured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contacts the peaks and fill the valleys of the thermoplastic structured surface of the first film.

In another embodiment, a method of injection molding is described comprising providing a thermoformed first film, as described herein, in a molding cavity; and injecting molten thermoplastic resin into the cavity.

In another embodiment, a multilayer film article is described comprising a) a first film comprising a thermoplastic structured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contacts the peaks and fill the valleys of the thermoplastic structured surface of the first film.

In another embodiment, a film suitable for use as a protective film is described comprising a planar base layer and structures disposed on the planar base layer.

The first film may be crystalline, such as in the case of polyolefins, or amorphous, such as in the case of PETg.

In typical embodiments, the second structures comprise an organic polymer material that is sufficiently crosslinked such that the organic polymer material lacks a thermal melt or softening temperature below the decomposition temperature of the crosslinked organic polymer material. In some embodiments, the second structures comprise an organic polymer material having a G' at the thermoforming temperature of less than 1, 0.5, or 0.1 MPa. The thermoforming temperature may range from 90° to 150°. In some embodiments, the second structures comprise an organic polymer material having a G' at the thermoforming temperature of less than or about equal to the G' of the first film at the thermoforming temperature. In some embodiments, the second protective film comprises a planar base layer (e.g. backing film) that comprises polyurethane or PETg.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective review of a Cartesian coordinate system of a surface that can be utilized to describe a structured surface;

FIG. 2 is a cross-sectional view of an illustrative structured surface;

FIG. 3 is a schematic side view of a multilayer polymer fdm comprising structured surfaces;

FIG. 4 is a perspective view of an illustrative structured surface with post-like structures;

FIG. 5 is a side view of an illustrative fluid transport structured surface;

FIG. 6 is a schematic view of a method of making a structured protective film by casting and curing a polymerizable resin on a thermoplastic structured film;

FIG. 7A is a top plan view of an illustrative three-dimensional thermally molded article; FIG. 7B is a side view of an illustrative three-dimensional thermally molded article;

FIG. 8 is a perspective view of an orthodontic aligner.

DETAILED DESCRIPTION

With reference to FIG. 3, the method and articles described herein comprise a multilayer polymer film 300 comprising: a) a first film 310 comprising a thermoplastic structured surface comprising peaks 301 and valleys 302; and b) a second protective film 350 comprising second structures that contacts the peaks and fill the valleys of the thermoplastic structured surface of the first film. The second protective film may be described as a negative replication of the thermoplastic structured surface. Thus, the peaks 351 of the second protective film coincide with the valleys of the thermoplastic structured surface. Likewise, the valleys 352 of the second protective film coincide with the peaks of the thermoplastic structured surface.

The second protective fdm may be characterized as a “premask”. The first film together with the second protective film (e.g. premask) are typically provided mated together as a multilayer film. The first film is separable from the second protective film at the structured interface. The second protective film may protect the thermoplastic structured surface of the first fdm during storage and during transport (e.g. to a customer). During thermoforming of the first film, the second protective film prevents or reduces the deformation of the thermoplastic structured surface. Prior to thermoforming, the first film may be described as generally planar except for the thermoplastic structured surface. After thermoforming, the first film is increasingly three-dimensional since the change in shape creates one or more cavities. After thermoforming the second structured protective film is removed from the thermoformed article. The second structured protective film (i.e. premask) is discarded (e.g. recycled).

The peaks and valleys of the structured surface of the first film and/or second protective film are typically disposed on a continuous (e.g. planar) land layer (320, 360). In some embodiments, the first film and/or second protective film further comprises a (e.g. backing) film 370. The backing film is disposed on the opposing major surface relative to the structured surface. In some embodiments, the (e.g. backing) film 370 is a different organic polymeric material than the thermoplastic stmctured surface. In other embodiments, the (e.g. backing) film 370 the same organic polymeric material as the thermoplastic structured surface.

In some embodiments, the first film and/or second protective film is a monolithic film. When the film is monolithic, the structured surface and underlying land layer comprise the same material and the film lacks a (e.g. backing) film. When the first and/or second film is monolithic the total thickness of the film is typically at least 50 microns and typically no greater than 1-2 mm. In some embodiments, the thickness is at least 100, 150, or 200 microns and no greater than 750 or 500 microns. The thickness of the land layer is typically at least 50, 100, or 150 microns. Depending on the thickness, the first film may also be characterized as a sheet or panel. The second protective film typically has a thickness no greater than 250 microns (10 mils).

When (e.g. backing) film 370 is present (as shown), the second protective film 350 may be characterized as a multilayer film. When a (e.g. backing) film is present on the opposing surface of the first film (not shown), the first film may be characterized as a multilayer film. In some embodiments, at least one of the first film or second protective film comprises a backing film. In some embodiment, both the first film and the second film comprise a backing film. In these embodiments, the structured surface and land layer may be thinner. In this embodiment, the thickness of the land layer is typically at least 0.5, 1, 2, 3, 4, or 5 microns ranging up to 50, 100, or 150 microns. In some embodiments, the thickness of the land layer is no greater than 45, 40, 35, 30, 25, 20, 15, or 10 microns. In an alternative embodiment, the land layer is absent or the land layer has a thickness approaching zero. In this embodiment, the land layer may have a thickness less than 0.5 microns (500 nanometers).

The first film (310) and thermoplastic structured surface (301 and 302) comprises a thermoplastic polymer. When the first film further comprises a backing, the backing is also thermoplastic, but may be a different thermoplastic polymer than the thermoplastic structured surface.

The most common thermoplastics used for thermoforming are acrylic (PMMA), acrylonitrile butadiene styrene (ABS), cellulose acetate, polyolefins such as low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyesters including copolyesters (e,g, PETg), polyamides including nylons. Other thermoplastic polymers include polyetherimide (PEI), polyphenylenesulphide (PPS), and fluoropolymers. All of these classes include polymers that can be melted, formed into films, and re-shaped via thermoforming into different forms.

In some embodiments, the first film comprises a polyester or a copolyester, which may include linear, branched or cyclic segments on the polymer backbone. Suitable polyesters and copolyesters may include ethylene glycol on the polymer backbone or may be free of ethylene glycol. Suitable polyesters include, but are not limited to, copolyesters with no ethylene glycol available under the trade designation TRITAN from Eastman Chemical, Kingsport, TN, polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETg), polycyclobexylenedimethylene terephthalate (PCT), polycyclohexylenedimethylene terephthalate glycol (PCTg), poh (1,4 cyck>hesylenedimetbylene) terephthalate (PCTA), polycarbonate (PC), and mixtures and combinations thereof. Suitable PETg resins, which contain no ethylene glycol on the poly er backbone, can be obtained from various commercial suppliers such as, for example, Eastman Chemical, Kingsport, TN; SK Chemicals, Irvine, CA; DowDuPont, Midland, MI; Pacur, Oshkosh, WI; and Scheu Dental Tech, Iserlohn, Germany. For example, EASTAR GN071 PETg resins and PCTg

VM318 copolyester resins from Eastman Chemical have been found to be suitable. Copolyester materials can be preferred for medical articles, such as dental appliances.

In some embodiments, the first film is not prepared from a (e.g. fluorinated or PDMS) low surface energy material, such as a fluoropolymer, and does not comprise a low surface energy coating, (i.e. a material or coating that on a flat surface has a receding contact angle with water of greater than 90, 95, 100, 105, or 110 degrees). In this embodiment, the microstructured surface is prepared from a material such that a flat surface of the material typically has a receding contact angle with water of less than 90, 85, or 80 degrees.

The first film comprising a thermoplastic structured surface typically comprises a thermoplastic material that reversibly can be softened and moldable at elevated temperatures and solidifies upon cooling and thus is solid at ambient temperature 25C°. It is appreciated that some thermosetting materials (e.g. prepregs) comprise a thermoplastic material mixed with curable liquid rubbers or (e.g. epox ) resin. Thus, as used herein, “thermoplastic structured surface” is intended to also include such thermoformable thermosetting materials.

The melt or softening temperature is a physical property of a thermoplastic As used herein the term thermal melt or softening transition temperature refers to the Vicat Softening Temperature measured according to ASTM D 1525 - 17 of an (e.g. amorphous) thermoplastic polymer or the melt temperature (Tm) of a thermoplastic polymer having crystallinity as measured by differential scanning calorimeter according to ASTM D3418.

In some embodiments, the first film has a thermal melt or softening transition temperature of at least 50, 55, 60, 65, 70, 75, or 80°C. The thermal melt or softening transition temperature is typically no greater than 450, 425, 400, 375, 350, 325, 300, 275, 250, 200, or 175°C. In some embodiments, the thermal melt or softening transition temperature is no greater than 170, 165, 160, 155, 150, 145, 140, 135, 130, 125 or 120°C.

In some embodiments, the first film has a glass transition temperature (Tg) (measured by differential scanning calorimeter according to ASTM D3418) of greater than 60, 65, 70, 75, or 80°C. The first film typically has a glass transition temperature of no greater than 140, 135, 130, 125 or 120°C.

In some embodiments, the first film has an elongation greater than 25, 50, 75, 100, 125, 150, or 200% at a rate of 300 mm/min. In some embodiments, the elongation at break is no greater than 500, 450, 400, 350, 300, 250, 200, 150, or 100% at a rate of 300 mm/min. In some embodiments, the first film has a tensile strength at beak of greater than 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, or 7500 at a rate of 300 mm/min. In some embodiments, the tensile strength at break is no greater than 7500, 7000, 6500, 6000, 5500, 5000, 4500, 3000 or at a rate of 300 mm/min.

In some embodiments, the first film and thermoplastic structured surface is a multilayer film comprised of two or more layers of different thermoplastic polymers. Schematic cross-sectional views of some embodied multilayer films for use for thermoforming and thermoformed (e.g. orthodontic aligner or retamer) articles are also described in WO2022/123440. The multilayered polymeric film used to form the (e.g. medical or packaging) article or dental appliance typically has a thickness of less than about 1.5 mm, 1 mm, 0.8 mm, or 0.5 mm.

The first film comprising a thermoplastic structured surface can be prepared by a variety of methods such as casting a molten thermoplastic using a tool having a stmctured pattern (e.g. thermal extrusion) or passing a thermoplastic film through a nip roll to compress against a tool having a structured pattern (e.g. embossing). The tool can be formed using any of a number of techniques known to those skilled in the art, selected depending in part upon the tool material and features of the desired topography. Illustrative techniques include etching (e.g., chemical etching, mechanical etching, or other ablative means such as laser ablation or reactive ion etching, etc., and combinations thereof), photolithography, stereolithography, micromachining, knurling (e.g., cutting knurling or acid enhanced knurling), scoring, cutting, etc., or combinations thereof. In some embodiments, the tool is a metal tool. The tool may further comprise a diamond like glass layer, such as described in W02009/032815 (David).

Illustrative Structured Surfaces

The surface protection film is surmised useful for protecting structures of most any size and shape during thermoforming including macrostructures, microstructures, and nanostructures.

In some embodiments, the structures may be characterized as macrostructures having a (e.g. peak) height and/or (e.g. peak width) width of at least 1 mm and typically no greater than 5 or 10 mm. Macrostructures are typically visible without a microscope. In some embodiments, the average length (the greatest dimension) of a macro structure can be in the same range as the average width or can be significantly greater than the width. For example, when the macro structure is a wood-grain macro structure as commonly found on a door, the length of the macro structure can extend the entire length of the (e.g. door) article. The height of the macrostructure is typically less than the width. In some embodiments, the height is less than 5, 4, 3, 2, 1, or 0.5 mm.

In some embodiments, the structures may be characterized as microstructures having a (e.g. peak) height and (e.g. peak width) width of at least 1 micron and/or nanostructures having a (e.g. peak) height and/or width of less than 1 micron. The structured surface is typically selected to provide a specific technical effect. Various structured surfaces are known in the literature. The base of each (e.g. micro)structure may comprise various cross-sectional shapes including but not limited to parallelograms with optionally rounded comers, rectangles, squares, circles, half-circles, half-ellipses, triangles trapezoids, other polygons (e.g. pentagons, hexagons, octagons, etc. and combinations thereof. In some embodiments, the peak structures may be described as posts, domes, ribs, prisms, or cube-comer elements.

With reference to FIG. 1, a micro structured surface can be characterized in three-dimensional space by superimposing a Cartesian coordinate system onto its stmcture. A first reference plane 124 is centered between major surfaces 112 and 114. First reference plane 124, referred to as the y-z plane, has the x- axis as its normal vector. A second reference plane 126, referred to as the x-y plane, extends substantially coplanar with surface 116 and has the z-axis as its normal vector. A third reference plane 128, referred to as the x-z plane, is centered between first end surface 120 and second end surface 122 and has the y-axis as its normal vector.

The thermoformed articles are three-dimensional on a macroscale. However, on a microscale (e.g. surface area that includes at least two adjacent microstructures with a valley or channel disposed between the microstmctures) the base layer/base member can be considered planar with respect to the microstructures. The width and length of the microstmctures are in the x-y plane and the height of the microstmctures is in the z- direction. Further, the base layer is parallel to the x-y plane and orthogonal to the z-plane.

FIG. 2 is an illustrative cross-section of a microstmctured surface 200. Such cross-section is representative of a plurality of discrete (e.g. post or rib) microstmctures 220. The microstmctures comprise a base 212 adjacent to an (e.g. engineered) planar surface 216 (surface 116 of FIG. 1 that is parallel to reference plane 126). Top (e.g. planar) surfaces 208 (parallel to surface 216 and reference plane 26 of FIG. 1) are spaced from the base 212 by the height (“H”) of the microstructure. The side wall 221 of microstructure 220 is perpendicular to planar surface 216. When the side wall 221 is perpendicular to planar surface 216, the microstmcture has a side wall angle of zero degrees.

Alternatively, microstmcture 230 has side wall 231 that is angled rather than perpendicular relative to planar surface 216. The side wall angle 232 can be defined by the intersection of the side wall 231 and a reference plane 233 perpendicular to planar surface 216 (perpendicular to reference plane 126 and parallel to reference plane 128 of FIG. 1).

In the case of privacy films, such as described in US 9,335,449; the side wall angle is typically less than 10, 9, 8, 7, 6, or 5 degrees. In other embodiments, the side wall angle is greater than 10, 15, 20, 25, 30, 35, 40, or 45 degrees.

In some embodiments, the stmctured surface comprises microstmctures wherein the maximum or average width of the valleys (i.e. Mv of FIG. 2) is at least 1, 2, 3, or 4 microns and more typically greater than 5, 6, 7, 8, 9, or 10 microns ranging up to 250 microns. In some embodiments, the width of the valleys is at least 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 microns. In some embodiments, the width of the valleys is at least 30, 35, 40, 45, or 50 microns. In some embodiments, the width of the valleys is at least 50, 55, 60, 65, 70, 75, 85, 85, 90, 95 or 100 microns. In some embodiments, the width of the valleys is at least 125, 150, 175, 200, 225, or 250 microns. In some embodiments, the width of the valleys is no greater than 1000, 950, 900, 850, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 225, 200, 175, 150, 125, 100, 75, or 50 microns.

In some embodiments, the maximum or average width of the peaks (i.e. Vm of FIG. 2) is about the same as the valleys. In other embodiments, the peak width is not the same as the valley width, yet may fall within the same ranges just described for the valleys.

The height of the peaks is typically within the same range as the maximum width of the valleys as previously described. In some embodiments, the peak structures typically have a height (H) ranging from 1 to 125 microns. In some embodiments, the height of the microstructures is at least 2, 3, 4, or 5 microns. In some embodiments, the height of the microstructures is at least 6, 7, 8, 9 or 10 microns. In some embodiments, the height of the microstructures no greater than 100, 90, 80, 70, 60, or 50 microns. In some embodiments, the height of the microstructures is no greater than 45, 40, 35, 30 or 25 microns. In some embodiments, the height of the microstructures is no greater than 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, or 10 microns. In typical embodiments, the height of the valley or channel is within the same range as just described for the peak structures. In some embodiments, the peak structures and valleys have the same height. In other embodiments, the peak structures can vary in height.

The aspect ratio of the valley is the height of the valley (which can be the same as the peak height of the structure) divided by the maximum width of the valley. In some embodiment the aspect ratio of the valley is at least 0.1, 0.15, 0.2, or 0.25. In some embodiments, the aspect ratio of the valley is no greater than 1, 0.9, 0.8, 0.7, 0.6 or 0.5. Thus, in some embodiments, the height of the valley is typically no greater than the maximum width of the valley, and more typically less than the maximum width of the valley.

In some embodiments, the peak structures comprise two or more facets. The peak structures have an apex that is sharp, rounded or truncated. The peak structures may have an apex angle ranging from 20 to 120 degrees or 80 to 100 degrees. In some embodiments, the (e.g. microjstructured surface comprises less than 50, 40, 30, 20 or 10% of flat surface area that is parallel to the planar base layer. In some embodiments, the facets may form continuous or semi-continuous surfaces in the same direction. In some embodiments, the valleys lack intersecting walls.

In some embodiments, the structured surface of the first film and thermoformed article is chosen to provide optical properties. In this embodiment, the thermoformed article has reflective (e.g. retroreflective) and/or refractive and/or diffractive properties. Illustrative structured surfaces include cube-comers (including preferred geometry) and brightness enhancing structured surfaces. The optical structured surface may be characterized as a hologram, diffuser, or antireflective surface.

In some embodiments, the structured surface of the first film and thermoformed article is chosen to provide fluid transport properties, such as described in US20017/0045284; incorporated herein by reference. An illustrative fluid transport (e.g. micro)structured surface comprising a plurality of channels is depicted in FIG. 5.

In some embodiments, the structured surface of the first film may prevent microorganisms (e.g. bacteria such as Streptococcus mutans, Staphyloccus aureus, or Psueodomonas aeruginosa) from being present on the structured surface or in other words reduces or prevents biofilm from forming. Various structured surfaces have been described in the literature including US2017/0100332, W02013/003373, and WO 2012/058605; incorporated herein by reference. In some embodiments, the stmctured surface comprises post-like structures, such as depicted in FIG. 4.

In some embodiments, the structured surface of the film may be chosen to provide one or more or the following properties: i) a reduction in microorganism touch transfer of at least 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 95, or 99%; ii) a log 10 reduction of microorganism (e.g. bacteria) of at least 2, 3, 4, 5, 6, 7 or 8 after cleaning; iii) at least 50, 60, 70, 80, 90% of the structured surface comprising cleaning solution 1-3 minutes after applying the cleaning solution to the (e.g. micro)structured surface. Structured surfaces of this type are described in WO2022/162528; incorporated herein by reference.

Structured Protective Laver

The organic polymer material of the second structures of the second protective fdm has suitable properties such that the presence thereof protects the thermoplastic structured surface, yet does not interfere with thermoforming.

In order for the second structures of the second protective film to protect the structures surface of the first film during thermoforming, the organic polymer material of the second structures is selected such that it does not melt at the thermoforming temperature of the first film.

In typical embodiments, the organic polymer material of the second structures of the structured protective film is sufficiently crosslinked such that it lacks a thermal melt or softening transition at a temperature up to the decomposition temperature of the material of the structured layer. The decomposition temperature can be measured using thermogravimetric analysis. Many organic polymers decompose at temperatures of 400°C. In some embodiments, the thermoforming temperature of the first structured thermoplastic film is less than 350, 325, 300, 275, 250, 225, 200, 175, or 150°C. In some embodiments, the thermoforming temperature is at least 90, 100, or 110°C (e.g. in the case of polyolefins). In other embodiments, the thermoforming temperature is at least 140°C (e.g. in the case of PETg).

Gel content is also indicative of crosslinking. The organic polymer material of the second structures of the structured protective film typically has a gel content (as measured according to the Gel Content Test Method described in the examples utilizing tetrahydrofuran (THF) of at least 20, 25 30, 35, or 40%. In some embodiments, the gel content is at least 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95%. The gel content is typically less than 100%, 99%, or 98%. The organic polymer material of the second structures of the second protective film also has suitable mechanical properties such that the presence thereof protects the thermoplastic structured surface, yet does not interfere with thermoforming.

In some embodiments, the organic polymer material of the second structures of the second protective film has a relatively low storage modulus, G', i.e. less than 1 MPa and in some embodiments less than 0.50 or 0.10 MPa at the thermoforming temperature. Notably, the exemplified organic polymer material of the second structures has a low storage modulus at thermoforming temperatures ranging from 93°C to 140°C and also has a low G' up to the decomposition temperature of the (e.g. crosslinked) organic polymer material of the second structures. Thus, the change in G' at 93°C as compared to 140°C is less than 1 MPa.

When the organic polymer material of the second structures of the second protective film has a low G' at a wide range of thermoforming temperatures, the same second protective film (e.g. premask) can be used for thermoforming a variety of different thermoplastic materials at different temperatures. When the organic polymer material of the second structures of the second protective film has a low storage modulus at room temperature 25°C, the second protective fdm typically further comprises a backing film having a higher modulus at room temperature to facilitate removal of the second structures from the structured surface of the first film.

In typical embodiments, the second stmctures comprise an organic polymer material having a G' at the thermoforming temperature of less than or about equal to the G' of the first film at the thermoforming temperature. About equal refers to +/- 10% of a statistical average G' value.

With reference to Table 7, in some embodiments, such as in the case of copolyesters (e.g. PETg), the first film comprising the thermoplastic structured surface also has a low G' at the thermoforming temperature, i.e. less than 1 MPa and in some embodiments less than 0.50 or 0.10 MPa. Since the organic polymer material of the second structures of the second protective film also has a low G' at the thermoforming temperature, the second protective film does not interfere with thermoforming.

In some embodiments, the first film or thermoplastic structured surface thereof has a greater G' at the thermoforming temperature. With reference to Table 5-6, when the first film or thermoplastic structured surface thereof comprises a crystalline thermoplastic material such as polyolefin (e.g. polyethylene or polypropylene), the G' at the thermoforming temperature may be at least 5, 6, 7, 8, 9 or 10 MPa. Although a second protective film having a low G' at the thermoforming temperature do not interfere with the thermoforming, it is surmised that the organic polymer material of the second structures of the second protective film may also have a higher G' provided the organic polymer material of the second structures of the second protective film has a G' at the thermoforming temperature less than or about equal to the G' of the first film comprising the thermoplastic structured surface. In this embodiment, the organic polymer material of the second structures of the second protective film may have a G' at the thermoforming temperature of at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 MPa. In some embodiments, the organic polymer material of the second structures of the second protective film may have a G' less than 10, 9, 8, 7, 6, 5, 4, 3, or 2 MPa. In some embodiments, the difference in G' between the first film comprising thermoplastic structured surface and the organic polymer material of the second structures of the second protective film is no greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 MPa.

In some embodiments, the second protective film further comprises a planar base layer. The planar base layer may also be described as a backing film. When a backing film is present, the G’ of the backing film at the thermoforming temperature is also typically less than or about equal to the G' of the first film comprising the thermoplastic structured surface. In some embodiments, the planar base layer (e.g. polyurethane or PETg backing fdm) of the second protective fdm has a G' less than 5, 4, 3, 2, 1, or 0.50 MPa at the thermoforming temperature.

In some embodiments, the structured protective film has tensile and elongation properties that fall within the same criteria previously described for the first film.

The Tg of the structured protective film, as measured by Dynamic Mechanical Analysis according to the test method described in the examples, is typically at least 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30°C ranging up to 55, 60, 65, or 70°C. In some embodiments, the Tg of the second layer is no greater than 50 or 45 °C. In some embodiments, the second layer exhibits a single Tg as measured by DSC. In other embodiments, the (meth)acrylic polymer can be characterized as having a dispersed phase of polyvinyl acetal (e.g. butyral) in a continuous phase of (meth)acrylic polymer.

In some embodiments, the structured protective layer comprises a (meth)acrylic polymer.

The (meth)acrylic polymer typically comprises polymerized units of one or more (meth)acrylate ester monomers derived from a (e.g. non-tertiary) alcohol containing 1 to 14 carbon atoms and preferably an average of 4 to 12 carbon atoms.

Examples of monomers include the esters of either acrylic acid or methacrylic acid with non- tertiary alcohols such as ethanol, 1 -propanol, 2-propanol, 1 -butanol, 2-butanol, 1 -pentanol, 2-pentanol, 3- pentanol, 2-methyl-l-butanol, 3 -methyl- 1 -butanol, 1-hexanol, 2-hexanol, 2-methyl-l -pentanol, 3-methyl- 1-pentanol, 2-ethyl-l -butanol; 3,5,5-trimethyl-l-hexanol, 3-heptanol, 1-octanol, 2-octanol, isooctylalcohol, 2-ethyl-l -hexanol, 1-decanol, 2-propylheptanol, 1-dodecanol, 1-tridecanol, 1- tetradecanol, and the like.

The (meth)acrylic polymer comprises polymerized units of one or more low Tg (meth)acrylate monomers, i.e. a (meth)acrylate monomer that when reacted to form a homopolymer has a T_g no greater than 0°C. In some embodiments, the low Tg monomer has a T_g no greater than -5°C, or no greater than - 10°C. The Tg of these homopolymers is often greater than or equal to -80°C, greater than or equal to - 70°C, greater than or equal to -60°C, or greater than or equal to -50°C.

The low Tg monomer may have the formula H2C=CR¹C(O)OR⁸, wherein R¹ is H or methyl and R⁸ is an alkyl with 1 to 22 carbons or a heteroalkyl with 2 to 20 carbons and 1 to 6 heteroatoms selected from oxygen or sulfur. The alkyl or heteroalkyl group can be linear, branched, cyclic, or a combination thereof. Exemplary low Tg monomers include for example ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2- methylbutyl acrylate, 2-ethylhexyl acrylate, 4-methyl-2 -pentyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, isotridecyl acrylate, octadecyl acrylate, and dodecyl acrylate. Low Tg heteroalkyl acrylate monomers include, but are not limited to, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate.

In some embodiments, the (meth)acrylic polymer comprises polymerized units of at least one low Tg monomer(s) having an alkyl group with 6 to 20 carbon atoms. In some embodiments, the low Tg monomer has an alkyl group with 7 or 8 carbon atoms. Exemplary monomers include, but are not limited to, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, isodecyl (meth)acrylate,-and lauryl (meth)acrylate. In some embodiments, the monomer is an ester of (meth)acrylic acid with an alcohol derived from a renewable source, such as 2-octyl (meth)acrylate.

The (meth)acrylic polymer typically comprises at least 10, 15, 20 or 25 wt-% of polymerized units of monofunctional alkyl (meth)acrylate low Tg monomer (e.g. having a Tg of less than 0°C), based on the total weight of the polymerized units (i.e. excluding inorganic filler or other additives). As used herein, wt-% of polymerized units refers to the wt-% based on the total weight of the (meth)acrylic polymer, and other organic components such as polyvinyl acetal (e.g. butyral) polymer and crosslinker when present. The (meth)acrylic polymer typically comprises no greater than 75, 70, 65, 60, 55, 50, 45, or 40 wt-% of polymerized units of monofunctional alkyl (meth)acrylate monomer having a Tg of less than 0°C, based on the total weight of the polymerized units.

The Tg of the homopolymer of various monomers is known and is reported in various handbooks. The Tg of some illustrative monomers is also reported in WO 2016/094277, incorporated herein by reference.

The (meth)acrylic polymer may comprise at least one (e.g. non-polar) high Tg monomer, i.e. a (meth)acrylate monomer when reacted to form a homopolymer has a Tg greater than 0°C. The high Tg monomer more typically has a Tg greater than 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, or 40°C.

In typical embodiments, the (meth)acrylic polymer comprises at least one high Tg monofunctional alkyl (meth)acrylate monomers including for example, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s- butyl methacrylate, t-butyl methacrylate, stearyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, isobomyl acrylate, isobomyl methacrylate, norbomyl (meth)acrylate, benzyl methacrylate, 3,3,5 trimethylcyclohexyl acrylate, cyclohexyl acrylate, and propyl methacrylate or combinations.

In some embodiments, the (meth)acrylic polymer comprises no greater than 30, 25, 20, or 10 wt- % of polymerized units of high Tg monofunctional alkyl (meth)acrylate monomer based on the total weight of the polymerized units (i.e. excluding inorganic filler or other additives). Greater amounts of polymerized units of high Tg monofunctional alkyl (meth)acrylate monomer can increase the G' of the (meth)acrylic polymer. Further, in some embodiments, the (meth)acrylic polymer comprises less than 1.0, 0.5, 0.1 wt-% or is free of polymerized units of high Tg monofunctional alkyl (meth)acrylate monomer.

In typical embodiments, the (meth)acrylic polymer further comprises at least 10, 15 or 20 wt-% and no greater than 65 wt.-% of polymerized units of polar monomers. Such polar monomers generally aid in compatibilizing the polyvinyl acetal (e.g. butyral) polymer with the high and low Tg alkyl (meth)acrylate solvent monomers. The polar monomers typically have a Tg greater than 0°C, yet the Tg may be less than the high Tg monofunctional alkyl (meth)acrylate monomer. Representative polar monomers include for example acid-functional monomers, hydroxyl functional monomers, nitrogencontaining monomers, and combinations thereof.

In some embodiments, the (meth)acrylic polymer comprises polymerized units of an acid functional monomer (a subset of high Tg monomers), where the acid functional group may be an acid per se, such as a carboxylic acid, or a portion may be salt thereof, such as an alkali metal carboxylate. Useful acid functional monomers include, but are not limited to, those selected from ethylenically unsaturated carboxylic acids, ethylenically unsaturated sulfonic acids, ethylenically unsaturated phosphonic acids, and mixtures thereof. Examples of such compounds include those selected from acrylic acid, methacrylic acid, itaconic acid, fumaric acid, crotonic acid, citraconic acid, maleic acid, oleic acid, b-carboxyethyl (meth)acrylate, 2-sulfoethyl methacrylate, styrene sulfonic acid, 2-acrylamido-2 -methylpropanesulfonic acid, vinylphosphonic acid, and mixtures thereof.

In some embodiments, the (meth)acrylic polymer comprises 0.5 up to 20 or 25 wt-% of polymerized units of acid functional monomers, such as acrylic acid. Greater amounts of polymerized units of acrylic acid can increase the G' of the (meth)acrylic polymer. In some embodiments, the (meth)acrylic polymer comprises at least 1, 2, 3, 4, or 5 wt.-% of polymerized units of acid-functional monomers. In other embodiments, the second layer comprises less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of acid-functional monomers.

In some embodiments, the (meth)acrylic polymer comprises non-acid-functional polar monomer.

One class of non-acid-functional polar monomers includes nitrogen-containing monomers. Representative examples include N-vinylpyrrolidone; N-vinylcaprolactam; acrylamide; mono- or di-N- alkyl substituted acrylamide; t-butyl acrylamide; dimethylaminoethyl acrylamide; and N-octyl acrylamide. In some embodiments, the (meth)acrylic polymer comprises at least 0.5, 1, 2, 3, 4, or 5 wt- % of polymerized units of nitrogen-containing monomers and typically no greater than 25 or 30 wt.-%. In other embodiments, the (meth)acrylic polymer comprises less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of nitrogen-containing monomers.

Another class of non-acid-functional polar monomers includes alkoxy -functional (meth)acrylate monomers. Representative examples include 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-(methoxyethoxy)ethyl, 2-methoxyethyl methacrylate, and polyethylene glycol mono(meth)acrylates. In some embodiments, the (meth)acrylic polymer comprises at least 0.5, 1, 2, 3, 4, or 5 wt.-% of polymerized units of alkoxy-functional (meth)acrylate monomers and typically no greater than 30 or 35 wt.-%. In other embodiments, the (meth)acrylic polymer less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of alkoxy -functional (meth)acrylate monomers.

The (meth)acrylic polymer may optionally comprise vinyl monomers including vinyl esters (e.g., vinyl acetate and vinyl propionate), styrene, substituted styrene (e.g., a-methyl styrene), vinyl halide, and mixtures thereof. As used herein vinyl monomers are exclusive of polar monomers. In some embodiments, the (meth)acrylic polymer comprises at least 0.5, 1, 2, 3, 4, or 5 wt-% and typically no greater than 10 wt.-% of polymerized units of vinyl monomers. In other embodiments, the (meth)acrylic polymer comprises less than 1.0, 0.5, 0.1 wt.-% or is free of polymerized units of vinyl monomers.

In some favored embodiments, the polymerized units of the (meth)acrylic polymer contain aliphatic groups and lack aromatic moieties. In typical embodiments, the (e.g. solvent) monomer(s) are polymerized to form a random (meth)acrylic polymer copolymer.

In some favored embodiments, the (meth)acrylic polymer further comprises a polyvinyl acetal polymer. The polyvinyl acetal polymer may be obtained, for example, by reacting polyvinyl alcohol with aldehyde, as known in the art and described in greater detail in previously cited WO2016/094277. The polyacetal resin is typically a random copolymer. However, block copolymers and tapered block copolymers may provide similar benefits to random copolymers.

The content of polyvinyl acetal (e.g. butyral) typically ranges from 65 wt-% up to 90 wt.-% of the polyvinyl acetal (e.g. butyral) polymer. In some embodiments, the content of polyvinyl acetal (e.g. butyral) ranges from about 70 or 75 up to 80 or 85 wt.-%. The content of polyvinyl alcohol typically ranges from about 10 to 30 wt.-% of the polyvinyl acetal (e.g. butyral) polymer. In some embodiments, the content of polyvinyl alcohol of the polyvinyl acetal (e.g. butyral) polymer ranges from about 15 to 25 wt.-%. The content of polyvinyl acetate of the polyvinyl acetal (e.g. butyral) polymer can be zero or range from 1 to 8 wt-% of the polyvinyl acetal (e.g. butyral) polymer. In some embodiments, the content of polyvinyl acetate ranges from about 1 to 5 wt-%.

In some embodiments, the alkyl residue of aldehyde comprises 1 to 7 carbon atoms. In other embodiments, the alkyl residue Ri of the aldehyde comprises 3 to 7 carbon atoms such as in the case of butylaldehyde (Ri = 3), hexylaldehyde (Ri = 5), n-octylaldehyde (Ri = 7). Of these, butylaldehyde, also known as butanal, is most commonly utilized. Polyvinyl butyral (“PVB”) polymer is commercially available from Kuraray under the trade designation “MOWITAL” and Solutia under the trade designation “BUTVAR”.

In some embodiments, the polyvinyl acetal (e.g. butyral) polymer has a Tg ranging from about 60°C up to about 75°C or 80°C, as measured by DSC. In some embodiments, the Tg of the polyvinyl acetal (e.g. butyral) polymer is at least 65 or 70°C. When other aldehydes, such as n-octyl aldehyde, are used in the preparation of the polyvinyl acetal polymer, the Tg may be less than 65°C or 60°C. The Tg of the polyvinyl acetal polymer is typically at least 35, 40 or 45°C. When the polyvinyl acetal polymer has a Tg of less than 60°C, higher concentrations of high Tg monomers may be employed in polymer B of the second layer composition in comparison to those utilizing polyvinyl butyral polymer. When other aldehydes, such as acetaldehyde, are used in the preparation of the polyvinyl acetal polymer, the Tg may be greater than 75°C or 80°C. When the polyvinyl acetal polymer has a Tg of greater than 70°C, higher concentrations of low Tg monomers may be employed in the second layer in comparison to those utilizing polyvinyl butyral polymer.

In some embodiments, the polyvinyl acetal (e.g. PVB) polymer typically has an average molecular weight (Mw) of at least 10,000 g/mole or 15,000 g/mole and no greater than 150,000 g/mole or 100,000 g/mole. In some favored embodiments, the polyacetal (e.g. PVB) polymer has an average molecular weight (Mw) of at least 20,000 g/mole; 25,000; 30,000, 35,000 g/mole and typically no greater than 75,000 g/mole.

In some embodiments, the (meth)acrylic polymer comprises 5 to 30 wt-% of polyvinyl acetal polymer such as polyvinyl butyral based on the total weight of the polymerized units of the (meth)acrylate polymer, polyvinyl acetal (e.g. butyral) polymer, and crosslinker when present. In some embodiments, the (meth)acrylic polymer comprises at least 10, 11, 12, 13, 14, or 15 wt-% of polyvinyl acetal (e.g. PVB) polymer. In some embodiments, the (meth)acrylic polymer comprises no greater than 25 or 20 wt.-% of polyyinyl acetal (e.g. PVB) polymer. When the (meth)acrylic polymer comprises a polyvinyl acetal (e.g. PVB) polymer having an average molecular weight (Mw) less than 50,000 g/mole, the (meth)acrylic polymer may comprise higher concentration polyvinyl acetal (e.g. PVB) polymer such as 35 or 40 wt-%. Thus, the (meth)acrylic polymer typically minor amount of polyvinyl acetal (e.g. PVB) resin in combination with a major amount of (meth)acrylic polymer. The amount of (methjacrylic polymer is typically at least 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95 wt-% of the structured protective layer.

In some favored embodiments, the (methjacrylic polymer comprises polymerized crosslinker units. In some embodiments, the crosslinker is a multifunctional crosslinker capable of crosslinking polymerized units of the (methjacrylic polymer such as in the case of crosslinkers comprising functional groups selected from (methjacrylate, vinyl, and alkenyl (e.g. C3-C20 olefin groups); as well as chlorinated triazine crosslinking compounds.

Examples of useful (e.g. aliphatic) multifunctional (methjacrylate include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, such as 1,6-hexanediol di(meth)acrylate, polyethylene glycol) di(meth)acrylates, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylates, and propoxylated glycerin tri(meth)acrylate, and mixtures thereof. One illustrative polyurethane di(meth)acrylate is commercially available from Sartomer as the trade designation CN996 (reported to have Tg of 8°C.)

Various other crosslinkers are known such crosslinking monomers that comprise a (methjacrylate group and an olefin group, such as described in WO 2014/172185; crosslinking monomers that comprise at least two terminal groups selected from allyl and/or methallyl, such as described in WO2015/157350; crosslinking monomers comprising as least two vinyl groups (e.g.

1,3-divinyl tetramethyl disiloxane); and triazine crosslinking compounds, such as described in US 4,330,590.

In yet other embodiments, the crosslinker comprises hydroxyl-reactive groups, such as isocyanate groups, capable of crosslinking alkoxy group of the (meth)acrylic polymer (e.g. HEA) or polyvinyl alcohol groups of the polyvinyl acetal (PVB). Examples of useful (e.g. aliphatic) multifunctional isocyanate crosslinkers include hexamethylene diisocyanate, isophorone diisocyanate, as well as derivatives and prepolymers thereof.

Various combinations of two or more of crosslinkers may be employed. The crosslinker is typically present in an amount of at least 0.5, 1.0, 1.5, or 2 wt.-% ranging up to 5, 6, 7, 8, 9, or 10 wt.-% based on the total weight of the polymerized units of the (meth)acrylate polymer and other organic components, such as polyvinyl acetal (e.g. butyral) polymer and crosslinker. Thus, the second layer comprises such amount of polymerized crosslinker units.

The thermoplastic structured film and/or structured protective film may optionally contain one or more conventional additives. Additives include, for example, antioxidants, stabilizers, ultraviolet absorbers, lubricants, processing aids, antistatic agents, colorants, impact resistance aids, fillers, matting agents, flame retardants (e.g. zinc borate) and the like. Some examples of fillers or pigments include inorganic oxide materials such as zinc oxide, titanium dioxide, silica, carbon black, calcium carbonate, antimony trioxide, metal powders, mica, graphite, talc, ceramic microspheres, glass or polymeric beads or bubbles, fibers, starch and the like.

When present, the amount of additive can be at least 0.1, 0.2, 0.3, 0.4, or 0.5 wt.-%. In some embodiments, the amount of additive is no greater than 25, 20, 15, 10 or 5 wt-% of the total structured protective film (i.e. total composition).

In some embodiments, the polymerizable composition of the structured protective layer is free of plasticizer, tackifier and combinations thereof. In other embodiments, the polymerizable composition of the structured protective layer comprises plasticizer, tackifier and combinations thereof in amount no greater than 5, 4, 3, 2, or 1 wt.-% of the total second layer composition.

Representative polymerizable compositions that are suitable for casting and curing on the thermoformable structured film are described in WO2016/094277; incorporated herein by reference.

One method of preparing the polymerizable composition of the structured layer includes partially polymerizing the monomer(s) to produce a composition comprising a (meth)acrylic polymer dissolved in unpolymerized solvent monomer(s). Another method comprises dissolving a polyvinyl acetal (e.g. PVB) polymer in unpolymerized monomer(s) of the (meth)acrylic polymer.

The polymerization is preferably conducted in the absence of unpolymerizable organic solvents such as ethyl acetate, toluene and tetrahydrofuran The polymerizable composition, typically comprising polymer and monomer, may be characterized as a coatable solution. The viscosity of the coatable composition is typically at least 1,000 or 2,000 cps ranging up to 100,000 cps at 25°C. In some embodiments, the viscosity is no greater than 75,000; 50,000, or 25,000 cps.

Method of Making Structured Protective Film

FIG. 6 is a schematic view of a method of making a stmctured protective film by casting and curing a polymerizable resin on a thermoplastic structured film. With reference to FIG. 6, the method comprises conveying the first film 610 comprising the thermoplastic structured surface. The method comprises depositing a polymerizable composition 680 (e.g. by use of a metered pump) onto the thermoplastic structured surface of the first film. The amount is sufficient to fill the valleys of the thermoplastic structured surface. In some embodiments, filling the valleys comprising conveying the polymerizable composition between a backing film 370 and the thermoplastic structured. One or more surfaces of backing 370 can optionally be primed or otherwise be treated to promote adhesion of the polymerized structured layer of the structured protective film to the base layer. In other embodiments, the structured protective film may lack a backing film. In this embodiment, the monolithic structured protective film comprises a thicker land layer as a planar base layer. After the polymerizable composition is deposited onto the thermoplastic structured surface of the first film, with or without a backing film, the polymerizable composition is cured by passing through a curing chamber.

The polymerizable composition of the structured protective film can be coated on the structured surface of the structured thermoplastic film using conventional coating techniques. For example, these polymerizable compositions can be applied by methods such as roller coating, flow coating, dip coating, spin coating, spray coating knife coating, and die coating. Coating thicknesses may vary depending on the desired thickness of the (e.g. radiation) cured structured protective film.

The polymerizable composition of the structured protective layer can be polymerized by various techniques, yet is preferably polymerized by solventless radiation polymerization, including processes using electron beam, gamma, and especially ultraviolet light radiation. In this (e.g. ultraviolet light radiation) embodiment, generally little or no methacrylate monomers are utilized. Thus, thee structured layer comprises zero or no greater than 10, 5, or 1 wt.-% of polymerized units of monomer having a methacrylate group.

The polymerizable composition typically comprises a photoinitiator. Useful photoinitiators include benzoin ethers such as benzoin methyl ether and benzoin isopropyl ether; substituted acetophenones such as 2, 2-dimethoxy -2 -phenylacetophenone photoinitiator, available under the trade name IRGACURE 651 orESACUREKB-1 photoinitiator (Sartomer Co., West Chester, PA), and dimethylhydroxyacetophenone; substituted a-ketols such as 2- methyl-2 -hydroxy propiophenone; aromatic sulfonyl chlorides such as 2-naphthalene-sulfonyl chloride; photoactive oximes such as 1- phenyl-l,2-propanedione-2-(O-ethoxy-carbonyl)oxime; mono- or bis- acrylphosphine oxides such as IRGANOX 819 or LUCIRIN TPO. Suitable photoinitiators are typically present in an amount of from 0.1 to 1.0 wt.-%.

Useful backing film materials include, for example, styrene-acrylonitrile, cellulosic polymers such as cellulose acetate butyrate and cellulose acetate propionate; cellulose triacetate, polyether sulfone, polymethyl methacrylate, polyurethane, polyester including biodegradable polylactic acid based polymers, polycarbonate, polyvinyl chloride, polystyrene, polyethylene naphthalate, copolymers or blends based on naphthalene dicarboxylic acids, polyolefins and olefin copolymers such as ethylene vinyl acetate, polyurethanes, polyimides, silicone (e.g. polysiloxane), fluoropolymers including fluoroelastomers, as well as biodegradable polymers such a polycaprolactone, polylactic acid polymers, polyethylene oxide and polycarboxylic acid. The base layer can contain mixtures of these polymers. The base layer can also be a multilayered film comprising two or more layers of such polymers. In addition, fiber- and/or particle-reinforced polymers can also be used. In typical embodiments, the backing film material is selected to have a G' less than or about equal to the G' of the first film comprising the thermoplastic structured layer as previously described.

The structured protective film is sufficiently transparent such that it may be irradiated with activating UV radiation having a UVA maximum in the range of 280 to 425 nanometers to polymerize the monomer component(s). UV light sources can be of various types. Low light intensity sources, such as blacklights, generally provide intensities ranging from 0.1 or 0.5 mW/cm² (millwatts per square centimeter) to 10 mW/cm² (as measured in accordance with procedures approved by the United States National Institute of Standards and Technology as, for example, with a UVIMAP UM 365 L-S radiometer manufactured by Electronic Instrumentation & Technology, Inc., in Sterling, VA). High light intensity sources generally provide intensities greater than 10, 15, or 20 mW/cm² ranging up to 450 mW/cm² or greater. In some embodiments, high intensity light sources provide intensities up to 500, 600, 700, 800, 900 or 1000 mW/cm². UV light to polymerize the monomer component(s) can be provided by various light sources such as light emitting diodes (LEDs), blacklights, medium pressure mercury lamps, etc., or a combination thereof. The monomer component s) can also be polymerized with higher intensity light sources as available from Fusion UV Systems Inc., Gaithersburg, MD. The UV exposure time for polymerization and curing can vary depending on the intensity of the light source(s) used. For example, complete curing with a low intensity light course can be accomplished with an exposure time ranging from about 30 to 300 seconds, whereas complete curing with a high intensity light source can be accomplished with shorter exposure time ranging from about 5 to 20 seconds. Partial curing with a high intensity light source can typically be accomplished with exposure times ranging from about 2 seconds to about 5 or 10 seconds.

The polymerizable composition bonds to the backing film (when present), yet does not bond to the thermoplastic structured surface of the first film. In some embodiments, this is preferably accomplished by selection of materials. For example, (meth)acrylic polymerizable compositions do not adhere to polyolefins. In other embodiments, this is accomplished by applying a silicone or fluorinated release agent to the thermoplastic structured surface of the first film prior to applying the polymerizable composition to the thermoplastic structured surface of the first film. Various release agents are known in the art.

After curing the polymerizable composition, the structured surface of the protective film is preferably non-tacky to the touch at room temperature (25°C) and at (e.g. storage or shipping) temperatures ranging up to (120°F) 50°C. In some embodiments, the structured protective film may exhibit a low level of adhesion to glass. For example, the 180° peel values can be about 2 oz/inch or less at a 12 inch/minute peel rate. The structured protective film does not permanently bond to the thermoplastic structured layer of the first film. Thus, it can easily be removed (e.g. by hand) from the first film before and after thermoforming.

Thermoforming

In one embodiment, a method of making a thermoformed article is described. The method generally comprises placing a multilayer film in a thermoforming apparatus. The multilayer film comprises a) a first film comprising a thermoplastic structured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contacts the peaks and fill the valleys of the thermoplastic structured surface of the first film. The method further comprises thermoforming the first film into an article while the second protective film is in contact with the peaks of the thermoplastic structured surface of the first film. In typical embodiments, the method further comprises removing the second protective fdm (e.g. premask) from the thermoformed article.

Thermoforming is a manufacturing process in which a thermoplastic sheet (also referred to as a film) is heated to a temperature where it becomes soft and flexible. Then the sheet is pressed into and stretched over a mold using air (both vacuum and compressed) pressure or pressed between molds using mechanical force to form it into the desired shape. The thermoforming process is usually segmented into thin-gauge (typically less than 5 mm) and thick-gauge markets. Thin gauge thermoforming as the name implies uses thin plastics and is used to manufacture rigid or disposable packaging items such as plastic cups, food containers, lids, or blisters, while thick gauge thermoforming is typically used to form more durable cosmetic permanent parts such as vehicle door inside panels and electronics packaging.

The thermoforming temperature is at or above the thermal melt or softening transition temperature of the first film comprising the thermoplastic structured surface. In some embodiments, the thermoforming temperature (e.g. of a crystalline material) is also above the glass transition temperature (Tg) of the thermoformable structured film or sheet. The thermoforming temperature may be at least 5, 10, 15, 20, or 25 degrees greater than the thermal melt temperature, the thermal softening transition temperature, or the Tg of the thermoformable structured film or sheet.

In some embodiments, the thermoforming pressure ranges from 15 to 500 psi. In some embodiments, the thermoforming pressure is at least 25 or 50 psi. In some embodiments, the thermoforming pressure is no greater than 400, 300, 200 or 100 psi. Also described is a method of injection molding comprising providing a thermoformed first film, as described herein, in a molding cavity and injecting molten thermoplastic resin into the cavity. Although the insert molding conditions can vary depending on the size of the article being made and the type of thermoplastic resin, typical insert molding conditions are described as follows:

Insert Molding Conditions

Thermoformed Article

In some embodiments, the thermoformed article may be a (e.g. sterile) medical article such as a wound contact layers, periodontal implants, dentures, dental crowns, contact lenses, intraocular lenses, soft tissue implants (breast implants, penile implants, facial and hand implants, etc..), surgical tools, sutures including degradable sutures, wound dressings, other implantable devices, and other indwelling devices. In some favored embodiments, the article is a dental article such as an orthodontic appliance or dental tray aligner.

Representative articles that would be cleaned during normal use and are amenable to being manufactured by thermoforming a structured film include various interior or exterior surfaces and components such as a) surface or component of a vehicle (e.g. automobile, bus, train, airplane, boat, ambulances, ships) as well as motorized and non-motorized shared vehicles such as car, scooters and bicycles including head rests, dashboards, door panels, window shutter (e.g. of an airplane), gear shifter, seat belt buckle, instrument and button panels, (e.g. plastic) seat back trays and arm rests, railings, cabin siding, luggage compartment, steering wheels, handlebars; b) housing and cases of an electronic device (e.g. phone, laptop, tablet, or computer) as well as keyboards and mouses (including mouse pads) and touchscreens, projectors, printers, remote control devices, locks, chargers (including cords & docking stations), fobs, video and arcade games, slot machines, automatic teller machines; (e.g. handheld) scanners, key cards, and point of sale electronic devices such as credit card readers, keypads, stylists, cash registers, barcode scanner, payment kiosks; c) shipping and packaging products; d) food preparation and dining surfaces, containers (including plates, bowls, cubs, water bottles) and films including galleys, carts, cutting boards, lunchboxes, thermos, appliances (e.g. microwave, stove, ovens, blenders, toasters, coffee makers, refrigerator including shelves and drawers), grills, beverage dispensers, utensils (e.g. especially handles thereof), menus, table tops and chairs (especially for public dining in restaurants, dorms, nursing homes, and prisons), garbage and recyclable containers; e) (e.g. non-sterile) surfaces of a medical, dental, or laboratory facility or medical, dental, or laboratory equipment (e.g. defibulators, ventilators and CPAPs (especially masks thereof), face shields, crutches, wheelchairs, bed rails, breast pump devices, IV pole, curing lights (e.g. for dental materials), exam tables, medical diagnostic equipment, such as described in WO 2021/236429; f) surfaces or components of furniture (e.g. desks, tables, chairs, seats and armrests); g) handles (e.g. knob, pull, levers including locks) of articles including furniture, doors of buildings (including push plates), turn styles, appliances, vehicles (interior and exterior door handles, transportation hand holds), shopping carts and baskets, exercise equipment, (e.g. cooking) utensils, tools, handlebars, levers of window blinds, microphone, luggage, etc.; h) building surfaces (including escalators and elevators) such as doors, railings, walls, flooring, countertops, desktops, cabinets, lockers, windows (e.g. sills), doorbells, electrical modulators (e.g. light switches, dimmers, and outlets including plates thereof); i) surfaces and components of lavatories (e.g. sink, toilet surfaces (e.g. levers), drain caps, shower walls, bathtub, vanity, countertop); j) articles for children including toys, car seats, cribs, changing tables, and playground equipment; k) cleaning equipment (e.g. vacuum, mop, scrub brush, dusters, toilet bowl cleaners, plunger, brooms) l) protective athletic and sports equipment (e.g. helmets, guards, balls for various sports including football, basketball, soccer, and golf); m) exercise, spa, and salon (e.g. hair styling and nail) equipment (e.g. weights, yoga mats); n) personal items including toothbrushes, eye glass frames, shoes, clothing, helmets, head bands, hard hats, headphones, footwear (e.g. shoes and boots), handbags, back packs; o) office and schools supplies and equipment including writing instruments (e.g. pencils, pens, markers), writable surfaces (including films and white boards), erasers, file folders, book and notebook covers, scanner and copy machines; p) manufacturing surfaces and equipment including conveyor belts, control panels for machine operation (e.g. of an assembly line). FIG. 8 depicts a representative thennoformed article, an orthodontic appliance 800, also referred to herein as an orthodontic aligner tray. Orthodontic appliance 800 may be characterized as a thin polymeric shell having a plurality of cavities 804 shaped to receive one or more teeth in the upper or lower jaw of a patient. Orthodontic aligner trays include cavities 804 that are shaped and configured to apply force to die teeth of the patient to resilient ly reposition one or more teeth from one tooth arrangement to a successive tooth arrangement. In the case of a retainer tray, the cavities 804 are shaped and configured to receive and maintain the position of one or more teeth that have previously been aligned.

The orthodontic appliance thennoformed article 800 is typically a monolithic or multilayered elastic polymeric material that generally conforms to a patient's teeth, and may be transparent, translucent, or opaque. The polymeric materials are selected to provide and maintain a sufficient and substantially constant stress profile during a desired treatment time, and to provide a relatively constant tooth repositioning force over the treatment time to maintain or improve the tooth repositioning efficiency of the orthodontic appliance.

One or both outer polymeric layers 814 and 810 of the thermoformed orthodontic article 800 comprises a microstructured and/or nano structured surface 1306 The first (e.g. external) major surface 806 contacts the tongue and cheeks of a patient during use of the article. The second (e.g. internal) surface 808 contacts the teeth of a patient during use of the article. The second (e.g. internal) surface 808 forms a cavity. The thermoformable (e.g. planar) base layer 812 is disposed between structured polymeric layers 810 and 1314. The thickness of the polymeric shell is orthogonal to the first and second major surface. In some embodiments, polymeric layer 806 is microstructured or nanostructured and polymeric layer 806 is unstructured or nanostructured.

In some embodiments, the thermoformed polymeric shell has an overall flexural modulus necessary to move the teeth of a patient. In some embodiments, the polymeric shell 102 has an overall flexural modulus of greater than 0.5, 0.6, 0.7, 0.8, 0.9 or 1 GPa. In some embodiments, the polymeric shell 102 has an overall flexural modulus of no greater than 1.5, 1.4 or 1.3 GPa.

Other thermoformed thin “polymeric shells” can have other three-dimensional shapes, such as the shape of a medical or non-medical face mask. In some embodiments, the polymeric shell is a packaging article. In another embodiment, the thermoformed article is a part, as depicted in FIG. 7A and 7B. Such thermoformed article has a cavity volume of 47.5 cc.

The thermoformed article 1000 further comprises side surfaces 1500 that correspond to the thickness of the article in the z-plane. In this embodiment, side surfaces 1500 are orthogonal to the x-y plane and orthogonal to the unmolded structured film. However, in other embodiments, the side surfaces 1500 may be angled or may have a complex surface.

During thermoforming the thermoplastic structured film is stretched in the x-y plane and in the z- plane. Topography maps of the thermoformed article can be obtained using 3D laser profiling which use laser triangulation, as described in WO 2022/123440; incorporated herein by reference. The stretch ratio can be determined by dividing the surface area of the three-dimensional thermoformed article by the two-dimensional area of the base layer of the film in the x-y plane (e.g. prior to thermoforming). The area of the structured film is determined by multiplying the length by the width. The surface area of the structures is not included in this calculation. In some embodiments, the stretch ratio is at least 0.25, 0.50. 0.75, 1.0, 1.5, 2.0, 2.5, or 3. In some embodiments, the stretch ratio is no greater than 10, 9.5, 9.0, 8.5, 8, 7.5, 7, 6.5, 6, 5.5, 5, 4.5, 4, 3.5, or 3. The stretch ratio is one way to express the change in shape that occurs when a structured film is thermoformed into a three-dimensional object.

Another way to express the change in shape of the structured film is the thickness of the thermoformed article in the z-reference plane or in other words the (e.g. average) height. The thermoformed article has a three-dimensional shape having an average height, “h” (relative to a x-y reference plane) of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mm. In some embodiments, the average height is at least 2, 3, 4, or 5 cm or greater. The average height is significantly greater than the thickness of the non-thermoformed base layer of the structured fdm from which it was formed. For example, the thickness of the base layer of the structured film can be 1 mm or less, whereas the height of the thermoformed article can be at least 2X (e.g. 2 mm), 3X, 4X, 5X, 6X, 7X, 8X, 9X or 10X the thickness of the non-thermoformed base layer of the structured film. In some embodiments, the height of the thermoformed article is no greater than 100X, 50X or 25X. In some embodiments, the height of the thermoformed article is no greater than 20X, 19X, 18X, 17X, 16X, 15X, 14X, 13X, 12X, UX or lOX the thickness of the non-thermoformed base layer of the structured fdm.

Another way to express the change in shape of the structured film is cavity volume. Disregarding the volume of the valleys of the structured surface, the structured film prior to thermoforming may be defined as having a cavity volume of nominally zero. The cavity volume of a thermoformed article is significandy greater than zero. The cavity volume of a thermoformed article can be determined by filling the thermoformed cavity with water or a removeable molding material, removing the water or molding material from the cavity, and then measuring the volume of the water or molding material that filled the cavity. In some embodiments, the volume is greater than 0.5, 1, 1.5 or 2 cc. In some embodiments, the cavity volume is at least 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50 cc or greater. For example, orthodontic aligners may have a cavity volume of about 15 cc. In some embodiments, the cavity volume may be no greater than 1000, 100, or 50 cc. The cavity volume increases with the size of the thermoformed article or component. For example, if the thermoformed article is a molded part of an airplane, the cavity volume may be much greater.

In general, the replication fidelity of the first film comprising the thermoplastic structured surface was significantly better when the second protective layer was present during thermoforming as compared to the same first film without the second protective layer.

In some embodiments, such as when the stretch ratio is relatively low, the thermoformed article has substantially the same (e.g. micro) structured surface as the first film comprising the thermoplastic structured surface prior to thermoforming. The dimension(s) of the structures of the thermoformed article, e.g. height, width, spacing (e.g. pitch) typically changes by no greater than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of the average value. The amount of change that is acceptable can depend on the function of the (e.g. micro) structured surface. For example, in the case of decorative surfaces, a greater amount of change in structure dimensions after thermoforming may be acceptable. Thus, in some embodiments, a change in dimension(s) of 15, 20, 25 or even 30% may be acceptable.

When the stretch ration is high the (e.g. micro)structured surface of the thermoformed article is typically different than the (e.g. micro)structured surface of the sheet or film prior to thermoforming. In some embodiments, the microstructured surface of the (e.g. unthermoformed) film or sheet prior to thermoforming is chosen such that the microstructured surface of the thermoformed articles has the desired dimensions for a particular technical effect. For example, the height of the peaks of the first film prior to thermoforming may be greater, such that the smaller peak height of the stretched (e.g. micro)structured surface of the thermoformed article is within a preferred range. As yet another example, the width of the valleys of the first film prior to thermoforming may be smaller such that the larger width of the stretched microstructured surface is within a preferred range. As yet another example, the apex angle of the peaks, included angle of the valleys, or side angle of the valleys may be smaller such that the larger angle of the thermoformed (e.g. micro)structured surface is within a preferred range.

EXAMPLES

Materials Preparatory Example 1. Structured Surface Film A

A polyethylene (PE) structured surface film of FIG. 5 having a thickness of 260 microns was prepared according to the extrusion replication process as described in the section “Preparation of microchannel fluid control film:” of the Examples Section of US 11392899 “Managing Condensation With Angled Fluid Control Features” with the exception that the hydrophilic coating was not applied. In Table 9, the primary ridge height, secondary ridge height, center-to-center distance (pitch) between primary ridges, and center-to-center distance (pitch) between secondary ridges is reported.

Preparatory Example 2. Structured Surface Film B (Post-Like Structures)

A polypropylene (PP) structured surface film of FIG. 4 having discrete post structures with angled sidewalls was prepared according to the molding process described in US8277922. The stmctured surface film had a total thickness of about 345 micrometers with a staggered array of 2000 conical posts per square inch. The posts had generally flat surfaces at the apex. In Tables 10-11, the dimensions for post height, diameter of the posts at the base in the down web direction, diameter of the posts at the base in the cross web direction, diameter of the posts at the apex in the down web direction, diameter of the posts at the apex in the cross web direction, center-to-center distance (pitch) between posts in the down web direction, and center-to-center distance (pitch) between posts in the cross web direction are reported.

Preparatory Example 3. Structured Surface Film C (Linear Prism Structures)

A PETg structured surface film having a thickness of 125 microns of FIG. 3 having linear prism features was prepared according to the molding process described in US8530021. In Table 12, the dimensions for peak height and tip-to-tip distance between peaks (pitch) are reported.

Preparatory Example 4. UV-curable Acrylate Composition for Preparing Structure Protective Film (Premask)

The components listed in Table 1 were combined in a light-proof glass jar and mixed overnight using a laboratory bottle roller instrument.

Table 1.

Preparatory Example 5. Preparation of Multilayer Films

The UV-curable acrylate composition of Preparatory Example 4 was two-roll coated at a thickness ranging from about 125 micrometers to 250 micrometers between a single structured surface film selected from Stmctured Surface Films A-C (Preparatory Examples 1-3) and a backing film and cured by further exposure to UV-A light. For Structured Surface Films A and B, a flat, polyurethane backing film (2 mil) was used. For Structured Surface Film C, a flat, PETg backing film (5 mil) was used. The resulting combination was exposed to a total UV-A energy of 1824 milliJoules/cm² using a plurality of fluorescent bulbs having a peak emission wavelength of 365 nanometers. The total UV-A energy was determined using a POWER PUCK II radiometer equipped with low power sensing head (EIT Incorporated, Sterling VA). The radiometer time and energy were then used to calculate the total exposure energy under the conditions for curing of the acrylic composition. Structured Surface Films A and B were coated as is. Prior to the coating procedure, the surface of Structured Surface Film C was sprayed with a mold release agent (E302 Rocket Release Spray, Stoner International, Hong Kong, China) to prevent the acrylic resin from sticking to the structured surface film.

Example 1. Thermoforming of Multilayer Films of Preparatory Example 5

The multilayer films prepared according to Preparatory Example 5 were thermoformed using a Hy-Tech ACCUFOR IMD IL50 Thermoformer (Hy-Tech Forming Systems Inc, Phoenix, AZ) with the process conditions listed in Table 2. A mold of the shape shown in FIGS 7A and 7B was used and the resulting thermoformed articles were reproduced with high fidelity. After thermoforming, film weed was removed.

Comparative Example A.

The same thermoforming procedure as described in Example 1 was followed with the exception that the acrylate protective film (premask) was removed from the laminate samples of Preparatory Example 5 before thermoforming.

Table 2. Thermoforming Conditions Example 2. Insert Molding

Thermoformed and trimmed samples from Preparatory Example 5 were placed in the cavity of an injection mold and insert molded using an Engel Model: EM 310/180 T WP US (Engel Machinery Inc., York, PA) using EXXONMOBIL PP1024E4 polypropylene homopolymer (EXXONMOBIL Corporation, Irving, TX) as the resin with the process conditions listed in Table 3.

Comparative Example B.

The same insert molding procedure as described in Example 2 was followed with the exception that the acrylate protective film (premask) was removed from the thermoformed samples before insert molding.

Table 3. Insert Molding Conditions Example 3. Dynamic Mechanical Analysis (DMA), Tensile, and Elongation Measurements of Films Films were analyzed by Dynamic Mechanical Analysis (DMA) using a DMA Q800 Instrument (TA Instruments, New Castle, DE) in tensile mode to characterize the physical properties of each sample as a function of temperature. Rectangular samples, 6.2 mm wide and 0.05-1.1 mm thick, were clamped into the film tension clamps of the instrument at 12-15 mm length. The furnace was closed and the temperature was equilibrated at -50 °C and held for 5 minutes. The temperature was then ramped from - 50 °C to 150 °C at 3 °C/minute while the sample was oscillated at a frequency of 1 Hertz and a constant strain of 0.1 percent. Results for Tg; Tan delta at 93 °C, 110 °C, 140 °C, storage modulus (G') at 93 °C, 110 °C, 140 °C, and loss modulus (G") at 93 °C, 110 °C, 140 °C are reported in Tables 4-7.

Tensile and elongation testing was conducted according to ASTM D882-10 “Standard Test Method for Tensile Properties of Thin Plastic Sheeting” using an INSTRON Model 4500 Universal Testing System (INSTRON Company, Norwood, MA) with a 1 kN load cell. Testing was performed at a rate of 300 mm/minute (11.81 inches/minute) for a total distance of 250 mm (9.84 inches). Samples were tested at least 24 hours after being prepared. A 0.5 inch (1.27 cm) wide strip of film was cut, and the thickness was determined for each sample using a micrometer. Typical sample length was 5-7 cm (2-3 inches). Test results were reported as the average of 3-5 sample replicates. The tensile strength (nominal) and percent elongation at break were determined, as described by 11.3 and 11.5 of ASTM D882-10. Tensile and Elongation results are reported in Table 8.

Table 4.

Table 5.

Table 8.

Example 4. Dimensional Measurements of Structured Surface Films 3 -Dimensional micrographs of microstructured film surfaces were taken using a Keyence VK- X3100 3D Surface Profilometer (Keyence Corporation, Itasca, IL) and measurements were taken using the accompanying VK-X 3000 MultiFileAnalyzer software package.

Measurements were taken of the microstructured features of surfaces of Structured Surface Films A-C (Preparatory Examples 1-3), the features of the microstructured surfaces after thermoforming with a protective film (Example 1 films), the features of the microstructured surfaces after thermoforming without a protective film (Comparative Example A films), the features of the microstructured surfaces after insert molding with a protective film (Example 2 films), the features of the microstructured surfaces after insert molding without a protective film (comparative Example B films). For each microstructured film surface three separate measurements were taken at random positions on the surface and the mean value (with standard deviation (SD)) was calculated. For thermoformed film samples containing a protective film, the protective film was removed prior to imaging and making the measurements. Three separate measurements were taken from the same location as indicated by an “X” in FIG 7A.

The results using the PE Structured Surface Film A of Preparatory Example 1 are reported in Table 9. The results using the PP Structured Surface Film B (post-like stmctures) of Preparatory Example 2 are reported in Tables 10 and 11. The results using the PETg Structured Surface Film C (linear prism structures) of Preparatory Example 3 are reported in Table 12.

Table 9. Feature Dimensions of Structured Surface Film A Before and After Thermoforming or Insert Molding **** = unable to measure, shape of structure feature was degraded

Table 10. Feature Dimensions of Structured Surface Film B (Post-Like Structures) Before and After Thermoforming or Insert Molding

Table 11. Feature Dimensions of Structured Surface Film B (Post-Like Structures) Before and After

Thermoforming or Insert Molding

**** = unable to measure, shape of structure feature was degraded

Table 12. Feature Dimensions of Structured Surface Film C (Linear Prism Stmctures) Before and After Thermoforming or Insert Molding

Claims

What is claimed is:

1. A method of making a thermoformed article comprising: providing a multilayer film in a thermoforming apparatus, wherein the multi-layer film comprises: a) a first film comprising a thermoplastic structured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contact the peaks and fill the valleys of the thermoplastic structured surface of the first film; and thermoforming the first film into an article at a thermoforming temperature while the second protective film is in contact with the thermoplastic stmctured surface of the first film.

2. The method of claim 1 further comprising removing the second structured protective film from the thermoformed article after thermoforming.

3. The method of claims 1-2 wherein the second structures comprise an organic polymer material that is sufficiently crosslinked such that the organic polymer material lacks a thermal melt or softening temperature below the decomposition temperature of the crosslinked organic polymer material.

4. The method of claims 1-3 wherein the second structures comprise an organic polymer material having a G' at the thermoforming temperature of less than 1, 0.5, or 0.1 MPa.

5. The method of claims 1-4 wherein the thermoforming temperature is in the range of 90° to 180°C.

6. The method of claims 1-5 wherein the second structures comprise an organic polymer material having a G' at the thermoforming temperature of less than or about equal to the G' of the first film at the thermoforming temperature.

7. The method of claims 1-6 wherein the second structures comprise a cured polymerizable resin.

8. The method of claim 7 wherein the second structures comprises a cured (meth)acrylic resin.

9. The method of claim 8 wherein the cured (meth)acrylic resin further comprises a polyvinyl acetal polymer.

10. The method of claims 1-9 wherein the second structures are disposed on a planar base layer comprising the same or different thermoplastic material as the first film.

11. The method of claims 1-10 wherein an interface between the thermoplastic structured surface and second protective film further comprises a release agent.

12. The method of claims 1-11 wherein the planar base layer comprises polyurethane or PETg.

13. The method of claims 1-12 wherein the thermoplastic structured surface comprise polyolefin or copolyester.

14. The method of claims 1-12 wherein the thermoplastic structured surface comprises microstructures having a height and width less than 1 mm and/or nanostructures having a height and/or width of less than 1 micron.

15. The method of claims 1-13 wherein the thermoplastic structured surface comprises posts, ribs, linear prisms, channels (e.g. truncated prisms), cube comer structures, or a combination thereof.

16. The method of claims 1-15 wherein the thermoformed article comprises a cavity having a volume of at least 10, 35, or 50 cc.

17. A thermoformed article comprising: a) a thermoformed first film comprising a thermoplastic structured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contacts the peaks and fill the valleys of the thermoplastic structured surface of the first film.

18. The article of claim 17 further characterized by claims 2-15.

19. A method of injection molding comprising: providing a thermoformed first fdm according to claims 1-18 in a molding cavity; injecting molten thermoplastic resin into the cavity.

20. A multilayer film article comprising: a) a first film comprising a thermoplastic stmctured surface comprising peaks and valleys; and b) a second protective film comprising second structures that contacts the peaks and fill the valleys of the thermoplastic structured surface of the first film; wherein a) and b) are further characterized according to claims 2-16.

21. The multilayer film of claim 20 for use for thermoforming the first structured film into an article.

22. A film suitable for use as a protective film comprising a planar base layer and structures disposed on the planar base layer further characterized according to claims 2-16.