Optical interlayers and methods of making same

Abstract

Optical interlayers, laminated composites, and improved methods for producing optical interlayers and laminated composites are provided. The optical interlayer film includes at least one surface having an embossed surface pattern having at least two channels extending in at least two non-parallel directions. The channel has a depth greater than about 20 [mu] m. The surface pattern enables removal of air between the interlayer and outer laminate sheets, thereby establishing the necessary seal therebetween, while minimizing premature edge seals. The laminated composites are particularly useful for safety glazing in various applications (e.g., automobiles, airplanes, trains or other means of transportation, display devices, windows of dwelling and other buildings, building facades, cabinets and / or load-bearing building structures (e.g., stairs and floors)).

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 419,259, filed on October 25, 2022, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0003] This specification generally relates to optical interlayers and laminated composites, such as laminated safety glass, and methods for producing such interlayers and composites. Background Art

[0004] Glass has been widely used in various building, vehicle, and display devices due to its transparency, airtightness, high strength, and hardness. To enhance the safety and applicability of glass, it is customary to place one or a thin layer of thermoplastic interlayer material between two glass sheets. When such laminated glass is subjected to an external impact, the glass may break, but the interlayer sandwiched between the component glass sheets is not easily damaged. Even after breakage, the glass remains adhered to the interlayer, so its fragments do not scatter. Thus, the body of any individual within a vehicle or building is protected from injury by glass fragments.

[0005] Laminated glass is typically produced by inserting an interlayer between two glass sheets, pulling the assembly onto nip rollers or placing it in a rubber bag, and evacuating the bag to achieve a preliminary contact bond between the glass sheets and the interlayer. Then, final contact bonding is carried out in an autoclave at elevated temperature and pressure.

[0006] The interlayer material is typically roughened or embossed with a surface pattern to minimize adhesion of one layer to another. Additionally, during construction of the assembly, this surface pattern can allow the interlayer to move while the two glass sheets are aligned. Unfortunately, this roughening of the interlayer surface causes air to become trapped in the gap between the glass surface and the thermoplastic interlayer body.

[0007] The trapped air can be removed by vacuum evacuation or by sandwiching the assembly between a pair of rollers. The extent to which air must be removed from between the glass and the interlayer will depend on the nature of the interlayer and its intended use. The presence of gas phase within the laminate will appear as bubbles or voids at the interlayer - glass interface. These bubbles or voids can increase the haze of the laminate and / or reduce its light transmittance, making the laminate less desirable in end - use applications where the laminate is used as a transparent article, such as safety glass or similar applications.

[0008] For certain applications, laminators encounter challenges in selecting suitable interlayers and suitable surface patterns for the interlayers. For example, an interlayer with a rougher surface can achieve faster air evacuation. However, such an interlayer can make it difficult to obtain sufficient edge sealing because more energy is typically required to compact the rough interlayer. If the edges of the preform are not fully sealed, during the autoclave step where the preform is heated under high pressure, air can penetrate the edges and can cause visual defects in the laminate, which are commercially unacceptable. Additionally, when the ambient temperature is significantly higher than 30 °C, an interlayer that is rough and achieves rapid air evacuation at approximately room temperature (23 °C) typically does not evacuate air well.

[0009] On the other hand, a relatively smooth interlayer can cause edge sealing before sufficient air has been removed and can trap air within the preform. This problem is commonly referred to as premature edge sealing and is particularly common in plasticized interlayers such as PVB. During autoclaving, the excess air can be forced into solution under high pressure but can return to the gas phase after autoclaving. Defects that appear after lamination typically require higher costs to repair.

[0010] There is a desire to provide improved optical interlayers having a rough and / or embossed surface that allows removal of air trapped between the interlayer and the outer sheet of the laminated composite. In particular, there is a desire to provide an embossed or rough surface that provides the necessary seal between the interlayer and the outer sheet while minimizing premature edge sealing, which otherwise would trap air or gas in the gap between the interlayer and the outer sheet. SUMMARY OF THE INVENTION

[0011] A simple summary of the claimed subject matter is presented below to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview of the claimed subject matter. It is neither intended to identify key elements of the claimed subject matter nor to describe the scope of the claimed subject matter. Its sole purpose is to present some concepts of the claimed subject matter in a simplified form as a prelude to a more detailed description that follows.

[0012] Optical interlayers, laminated composites, and methods for producing the interlayers and composites are provided. In various embodiments, the optical interlayers described herein have a embossed or rough surface that, when the interlayer is used, for example, in a laminated composite, allows air to be removed between the interlayer and one or more outer laminated sheets. This creates the necessary seal between the interlayer and the outer sheet while also minimizing premature edge sealing. In various embodiments, the laminated composites described herein have a relatively low haze and high light transmittance and are thus particularly useful for various applications where an optically transparent laminate may be required (e.g., windows for automobiles, airplanes, trains, or other modes of transportation, display devices, windows for residential and other buildings, building facades, cabinets, and / or load-bearing building structures (such as stairways and floors)) as safety glass.

[0013] In one aspect, the optical interlayer film comprises at least one surface having an embossed surface pattern with at least two channels extending in at least two non-parallel directions. The depth of the channels is greater than about 20 μm.

[0014] In various embodiments, the depth of the channels is greater than about 30 μm or is from about 30 μm to about 50 μm, preferably from about 35 μm to about 43 μm. The width of the channels can be from about 30 μm to about 900 μm or from about 400 μm to about 600 μm. For example, the width can be measured from the midpoint of the channel depth.

[0015] The interlayer can comprise a non-plasticized or plasticized thermoplastic material. In certain embodiments, the interlayer comprises a non-plasticized thermoplastic material. Suitable thermoplastic materials include polyurethane interlayers, ethylene vinyl acetate interlayers, ethylene acid copolymer interlayers, ionomeric materials, or combinations thereof. In an exemplary embodiment, the material comprises non-plasticized thermoplastic polyurethane (TPU).

[0016] The interlayer film can have a second surface opposite the first surface. The second surface has an embossed surface pattern with at least two channels extending in at least two non-parallel directions. The depth of the channels is greater than about 20 μm, or greater than about 30 μm. The second embossed pattern can be the same as or different from the first embossed pattern. For example, the embossed pattern and / or its depth can be asymmetric with respect to the two sides of the interlayer film.

[0017] The channels can be formed by imprinting protrusions on the base surface of the interlayer film. In some embodiments, depressions or voids are also formed in the base surface. This configuration reduces the energy required to flatten the interlayer between, for example, two rigid sheets in a laminate. In these embodiments, the depth of the channels is measured from the peak of the protrusion to the lowest point or valley of the depression.

[0018] In various embodiments, the embossed pattern includes a first set of channels extending in a first direction and spaced from each other by a distance of about 100 μm to about 1,000 μm, and a second set of channels extending in a second direction and spaced from each other by a distance of about 100 μm to about 1,000 μm. The first set of channels extends in a direction non-parallel to the second set of channels. In an exemplary embodiment, the first set of channels is substantially perpendicular to the second set of channels.

[0019] The thickness of the optical interlayer film can be less than about 0.08 inches. In certain embodiments, the thickness is less than about 0.02 inches or is about 0.014 to about 0.017 inches, or about 0.15 inches. In an embodiment, the 85° gloss of the embossed surface of the interlayer film is about 14 to about 20, or about 15 to about 17.

[0020] The optical interlayer film provided herein is particularly suitable for laminates that include first and second substantially rigid sheets on either side of the interlayer film. The rigid sheets can include rigid plastic materials such as polycarbonate and / or glass. The embossed surface pattern on the interlayer provides a plurality of substantially uninterrupted channels in at least two directions for venting air between the interlayer and the outer rigid sheets. The depth of the channels allows air to escape during the lamination process without prematurely sealing the edges of the interlayer to the glass. The resulting laminate has a sufficiently low haze and high light transmittance to be used as safety glass for various applications.

[0021] In another aspect, the laminate includes at least one layer of glass and an interlayer film adhered to the layer of glass. The interlayer film includes at least one surface facing the layer of glass and having an embossed surface pattern having at least two channels extending in at least two non-parallel directions. Prior to lamination, the depth of the channels is greater than about 20 μm, or greater than about 30 μm.

[0022] In various embodiments, the laminate includes a second layer of glass, wherein the interlayer film is located between the first layer of glass and the second layer of glass. The interlayer film can have a second surface opposite the first surface and facing the second layer of glass. The second surface has an embossed surface pattern having at least two channels extending in at least two non-parallel directions. Prior to lamination, the depth of the channels is greater than about 20 μm, or greater than about 30 μm.

[0023] In various embodiments, the interlayer includes a non-plasticized thermoplastic material. Suitable thermoplastic materials include polyurethane interlayers, ethylene vinyl acetate interlayers, ethylene acid copolymer interlayers, ionomeric plastic materials, or combinations thereof. In an exemplary embodiment, the material includes non-plasticized TPU.

[0024] In various embodiments, the laminate has a relatively low haze (as measured by ASTM D1003) of from about 0.8% to about 0.9%, or from about 0.82% to about 0.86%, or about 0.84% after lamination.

[0025] In various embodiments, the laminate has a relatively high light transmittance (measured by ASTM D1003) of from about 85% to about 95% or from about 89% to about 90% after lamination.

[0026] The laminate may include a single optical interlayer film or multiple interlayer films sandwiched between outer rigid sheets (i.e., glass or polycarbonate). In the latter embodiment, each interlayer film may include surface patterns on one or both sides of the interlayer film, such as those described above.

[0027] In another aspect, a method of producing an optical interlayer film includes forming an embossed pattern on a calender roll and transferring the embossed pattern to the surface of the optical interlayer film such that the surface has at least two channels extending in at least two non-parallel directions and the depth of the channels is greater than about 20 μm.

[0028] In various embodiments, the calender roll may include metal, rubber, or a combination thereof. In an exemplary embodiment, the calender roll includes a metal roll and a rubber roll. The metal roll is engraved with a surface pattern and pressed against one surface of the interlayer, while the rubber roll is pressed against the opposite surface of the interlayer.

[0029] In an embodiment, the method further includes transferring a second embossed pattern to the second surface of the interlayer film opposite the first surface. The second embossed pattern may be the same as or different from the first embossed pattern. In an exemplary embodiment, the second embossed pattern has at least two channels extending in at least two non-parallel directions and the depth of the channels is greater than about 20 μm.

[0030] The method may further include placing the optical interlayer film between a first sheet and a second sheet of glass to obtain a laminated structure and subjecting the laminated structure to vacuum lamination to remove the air trapped between the interlayer film and the glass sheets.

[0031] The recitation herein of the desired objectives met by the various embodiments of the present specification is not intended to imply or indicate that any one or all of these objectives exist as an essential feature, either individually or jointly, in the most general embodiment of the present specification or any of its more specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a graphical description of a surface pattern on one surface of the optical interlayer;

[0033] Figure 2is a top view of the surface pattern of an optical interlayer measured along a diagonal line passing through the interlayer;

[0034] Figure 3 is a diagram showing Figure 2 the height and width of a channel along the diagonal line of; and

[0035] Figure 4 is a diagram showing the S t or the frequency distribution of the peak height of channels formed in the surfaces of multiple optical interlayers. DETAILED DESCRIPTION

[0036] This specification and the drawings illustrate exemplary embodiments and should not be considered limiting. The claims (including equivalents) define the scope of this specification. Various mechanical, compositional, structural, and operational changes may be made without departing from the scope of this specification and the claims (including equivalents). In some cases, well-known structures and techniques are not shown or described in detail to avoid obscuring the description. Similar numerals in two or more figures represent the same or similar elements. Additionally, whenever practical, elements and their related aspects described in detail with reference to one embodiment may be included in other embodiments not specifically shown or described. For example, if an element is described in detail with reference to one embodiment and not described with reference to a second embodiment, that element may still be required to be included in the second embodiment. Further, the descriptions herein are for illustrative purposes only and do not necessarily reflect the actual shape, size, or dimensions of the systems or the components shown.

[0037] It should be noted that, as used in this specification and the appended claims, the singular forms "a", "an", and "the" and the use of any word in the singular include plural referents unless explicitly and unambiguously limited to one referent. As used herein, the term "comprising" and its grammatical variants are intended to be non-limiting, such that the recitation of items in a list does not preclude other similar items that may be substituted or added to the listed items.

[0038] Unless otherwise stated, any quantitative value is approximate whether or not the words "about" or "approximate" are stated. The materials, methods, and examples described herein are illustrative only and are not intended to be limiting.

[0039] Optical interlayers and laminated composites, such as safety glass laminates, etc., are provided. Additionally, improved methods for producing optical interlayers and laminated composites are provided. Various embodiments of the systems and methods described herein have a textured or rough surface that allows air to be removed between the interlayer and the glass, thereby establishing a necessary seal therebetween while minimizing premature edge sealing.

[0040] The optical interlayer described herein is a thermoplastic interlayer that can be heated and bonded to other interlayer materials, rigid plastic materials, and / or glass. Laminates containing the interlayers described herein are particularly suitable for use as safety glass in a variety of applications. For example, these laminates can be suitable for use in automobiles, airplanes, trains, or other modes of transportation that contain windows or transparent apertures, where the safety glass can be used to protect the occupants or contents of the vehicle. Other suitable applications of safety glass are well known and include, for example, windows in residential and other buildings, building facades, cabinets, load-bearing building structures (such as stairs and floors).

[0041] The appearance and transparency of the transparent laminate are important features for evaluating the desirability of using the laminate. One factor that affects the appearance of the laminate is, for example, whether the laminate includes trapped air or bubbles that are generated between the interlayer and the glass surface. It is desirable to remove the air in an efficient manner during the lamination process.

[0042] Providing channels for air escape and removing air during the lamination process are known methods for obtaining a laminate with an acceptable appearance. This can be achieved by mechanically embossing the interlayer sheet (or by melt fracture during the extrusion process) and then quenching it in order to maintain the roughness during the processing. Maintaining the surface roughness is crucial for the efficient expulsion of trapped air during the laminate preparation process.

[0043] The interlayer contains a non-plasticized or plasticized thermoplastic material. In certain embodiments, the material is non-plasticized. Suitable thermoplastic materials include polyurethane interlayers, ethylene vinyl acetate interlayers, ethylene acid copolymer interlayers, ionomeric plastic materials, and the like. In an exemplary embodiment, the material comprises non-plasticized thermoplastic polyurethane (TPU). TPU is a class of polyurethane plastics that have a variety of properties, including elasticity, transparency, and resistance to oils, greases, and abrasion.

[0044] The surface pattern is preferably an embossed pattern. The channel depth is from about 20 μm to about 80 μm. Preferably, the depth of the channel is greater than about 30 μm or is from about 30 μm to about 50 μm, preferably from about 35 μm to about 43 μm. Preferably, the depth is selected such that the regular channels provide a suitable path for air escape during the lamination process. Thus, it is desirable for the depth to be deep enough so that the air channels are not prematurely cut off during the heating stage of the lamination process, as premature cutting off of the air channels can result in trapped air when the laminate cools.

[0045] The sandwich sheet can be embossed on one or both sides. The embossing pattern and / or its depth can be asymmetric with respect to the two sides of the sandwich sheet. That is, the embossing patterns can be the same or different, and the pattern depths on either side of the sheet can also be the same or different. In a preferred embodiment, each side of the sandwich sheet of the present invention has an embossing pattern, wherein the depth of the pattern on each side is greater than about 20 μm. In certain embodiments, one side of the sandwich sheet has an embossing pattern that is orthogonal to the edge of the sheet, and the same embossing pattern is inclined at an angle greater than or less than 90° with respect to the edge, and the depth of the embossing pattern is greater than about 20 microns. Offsetting the pattern in this way can eliminate undesirable optical effects in the sheet.

[0046] The channel width can be measured from the midpoint between the top and bottom of the channel (i.e., half of the distance between the valley depth and the peak height as discussed below). The width of the channel at this midpoint can be from about 30 μm to about 900 μm or from about 400 μm to about 600 μm.

[0047] In an embodiment, the embossing pattern comprises a first set of channels that extend in a first direction and are spaced from each other by a distance of about 100 μm to about 1,000 μm or about 300 μm to about 800 μm, preferably about 500 μm to about 700 μm. The embossing pattern can include a second set of channels that extend in a second direction and are spaced from each other by a distance of about 100 μm to about 1,000 μm or about 300 μm to about 800 μm, preferably about 500 μm to about 700 μm. The first channels extend in a direction that is not parallel to the second channels. In an exemplary embodiment, the first channels are substantially perpendicular to the second channels.

[0048] Of course, it should be recognized that other patterns can be formed in the sandwich. For example, the surface pattern can include three or more sets of different channels that extend in three or more directions.

[0049] Now referring to Figure 1 , an example of the surface pattern on the optical sandwich 10 provided herein has a base surface 30, which generally represents the original substantially flat surface of the sandwich before the surface pattern is formed. The surface pattern includes protrusions 20 that project upward from the base surface 30 and voids or depressions 40 in the sandwich surface 30. Such protrusions 20 and depressions 30 can have different volumes, or they can have substantially the same volume, and they are located on the sandwich surface in positions close to other such protrusions and depressions.

[0050] The protrusions and depressions are preferably located such that heating and compressing the surface of the sandwich causes the thermoplastic material to flow more locally from the region of higher thermoplastic mass (i.e., the protrusions) to the void regions (i.e., the depressions), where such voids will be filled with mass from the local protrusions, resulting in the flattening of the sandwich surface. The local flow of the thermoplastic resin material to obtain a flat surface will require less energy input than more conventional patterns (i.e., patterns with only protrusions and no depressions), which require the mass of the thermoplastic material to flow across the entire sandwich surface to flatten the surface.

[0051] In an alternative embodiment, the surface pattern includes only protrusions (i.e., no depressions). In this embodiment, the channel depth is measured from the base surface 30 to the top of the protrusion 30.

[0052] The thickness of the optical sandwich film can be less than about 0.08 inches. In certain embodiments, the thickness is less than about 0.02 inches or is about 0.014 to about 0.017 inches, or about 0.15 inches.

[0053] In one embodiment, the average peak height or S of each protrusion p ranges from about 5 μm to about 50 μm, or about 20 μm to about 40 μm, preferably about 25 μm to about 30 μm. The average depth or S of each void or depression v ranges from about 5 μm to about 40 μm, or about 10 μm to about 20 μm, preferably about 12 μm to about 16 μm. Thus, the average height of each channel (i.e., the distance from the peak height to the valley depth) is greater than about 30 μm or is about 30 μm to about 50 μm, preferably about 35 μm to about 43 μm.

[0054] The kurtosis of the surface pattern (i.e., a measure of the combined weight of the distribution tails relative to the center of the distribution) is preferably less than about 5.0, or less than about 3.0. The skewness of the surface pattern (i.e., a measure of the asymmetry of the probability distribution of the height relative to its mean) is preferably about 0.8 to about 0.85.

[0055] Table 1 below shows an example of the peak height and valley depth of the surface pattern.

[0056] Table 1

[0057] <![CDATA[S p > 28.1 μm Peak height <![CDATA[S v > 14.33 μm Valley depth <![CDATA[S t > 42.43 μm Maximum peak-to-valley height <![CDATA[S a > 7.95 μm Arithmetic mean height <![CDATA[S q > 9.487 μm Root mean square height <![CDATA[S sk > 0.8216 Skewness <![CDATA[S ku > 2.551 Kurtosis

[0058] As shown in Table 1 above, the arithmetic mean height S of the sample a is about 7.95 μm, and the root mean square height is about 9.487 μm. The kurtosis (i.e., a measure of the combined weight of the distribution tails relative to the center of the distribution) is about 2.551, and the skewness (i.e., a measure of the asymmetry of the probability distribution of the height relative to its mean) is about 0.8216.

[0059] The surface patterns generated on the interlayer increase the gloss of these surfaces. In one embodiment, the 85° gloss of the embossed surface of the interlayer is from about 12 to about 20, or from about 15 to about 17. In certain embodiments, the embossed surface pattern increases the 85° gloss of the interlayer by about 10 to about 15, or about 12 to about 13.

[0060] This optical interlayer film is particularly suitable for laminates that include first and second substantially rigid sheets located on either side of the interlayer film. The rigid sheets can include rigid plastic materials such as polycarbonate and / or glass. In one embodiment, the sheets include annealed glass having a thickness of from about 2.5 mm to about 5.0 mm, or from about 3.0 mm to about 3.5 mm.

[0061] The laminate can include a single optical interlayer film or multiple interlayer films sandwiched between outer rigid sheets (i.e., glass or polycarbonate). In the latter embodiment, each interlayer film can include surface patterns on one or both sides of the interlayer film. Such as the surface patterns described. In a preferred embodiment, each interlayer film includes surface patterns on both sides of the film.

[0062] In an embodiment, the laminate has a relatively low haze and high light transmittance (measured by ASTM D1003) after lamination, which makes them particularly suitable for applications requiring optical transparency. In one such embodiment, the haze of the laminate is from about 0.8% to about 0.9%, or from about 0.82% to about 0.86%, or about 0.84%. The light transmittance is from about 85% to about 95% or from about 89% to about 90%.

[0063] A method for producing an optical interlayer film will now be described. By standard techniques such as milling engraving, etching (e.g., photoengraving), and / or machine engraving, an embossed pattern is engraved onto a calender roll. In certain embodiments, the calender roll can comprise metal, rubber, or a combination thereof. In an exemplary embodiment, the calender roll includes a metal roll and a rubber roll. The metal roll is imprinted with a surface pattern, and the interlayer is advanced through the roll such that the metal roll faces one surface of the interlayer and the rubber roll faces the opposite surface.

[0064] Then, the optical interlayer feed is passed through the roll to transfer the surface pattern onto one surface of the interlayer film such that the surface has at least two channels extending in at least two non-parallel directions, and the depth of the channels is greater than about 20 μm. The surface pattern on the interlayer can include peaks extending above the base surface and depressions extending below the base surface.

[0065] In an embodiment, the method further includes transferring a second embossed pattern to a second surface of the interlayer film that is opposite to the first surface. The second embossed pattern may be the same as or different from the first embossed pattern. In an exemplary embodiment, the second embossed pattern has at least two channels extending in at least two non-parallel directions, and the depth of the channels is greater than about 20 μm. The interlayer may be passed through a second calender roll, and the metal roll embosses the opposite surfaces of the interlayer. Optionally, the interlayer may be flipped so that the opposite surface faces the embossing metal roll.

[0066] The method may further include placing an optical interlayer film between a first sheet and a second sheet of rigid material (such as glass) to obtain a laminated structure, and performing vacuum lamination on the laminated structure.

[0067] Examples

[0068] Various TPU interlayer sheets with an embossed surface pattern are produced. First, the surface pattern is engraved into the surfaces of the first and second calender rolls. The calender rolls include a metal roll and a rubber roll. The surface pattern is imprinted into the metal roll. A thermoplastic polyurethane (TPU) material is fed through the rolls to transfer the surface pattern to one surface of the interlayer. The surface pattern on the interlayer includes peaks extending above a base surface and depressions extending below the base surface.

[0069] As shown in Table 2 below, six different rolls of interlayer material (Rolls 8 - 13) are provided, and the applicant measured the dimensions of the surface patterns of three different samples from each roll. Table 2 presents the average values of these three different samples. As shown, the depth of each channel (Roll average S t ) was measured as the distance between the peak of each protrusion and the depth of each void located near the protrusion. The average values of the 3 samples from each roll ranged from about 35.92 μm (Roll 13) to about 41.02 μm (Roll 8).

[0070] The average 85° gloss of the embossed surface of the interlayer (i.e., the side facing the metal roll) is about 15 to 17 (specifically about 15.04 to about 16.71). Conversely, the average 85° gloss of the opposite surface of the interlayer (i.e., the side facing the rubber roll) is about 3.04 to about 3.82. Thus, the embossed surface pattern increases the 85° gloss of the interlayer by an average of about 12 to about 13.

[0071] As shown in Table 2, the average gauge or thickness of the interlayer samples is about 0.015 inches. The minimum thickness is about 0.014 inches, and the maximum thickness is about 0.017 inches.

[0072] Table 2

[0073]

[0074]

[0075] Figure 2 and Figure 3 shows the line roughness of one of the rollers (roller 9). As shown, a diagonal line is drawn across the interlayer surface and the height is measured along the diagonal. The baseline or "zero μm" height is at the bottom of each depression or void. As shown, the total height or S of each channel t is between approximately 34 μm and 40 μm. The distance between the peaks of each channel is from approximately 600 μm to approximately 700 μm, and the width of each channel (measured at the midpoint of the channel height) is from approximately 400 μm to approximately 600 μm.

[0076] Figure 4 shows the overall frequency of S values of various interlayers produced by the applicant. As shown, the frequency generally corresponds to a bell-shaped curve, and the average value or the S at the top of the curve t is approximately 36 μm, and the width or standard deviation of the curve is approximately 12 μm (i.e., from approximately 32 μm to 44 μm). Although the bell-shaped curve includes some outliers, i.e., the S of one interlayer t is approximately 30 μm, and the S of five outliers t is greater than 42 μm, the S of all the interlayers produced t is at least 30 μm. t All are at least 30 μm.

[0077] Then, the embossed interlayer material is placed between two pieces of glass. Then, the sandwich structure is loaded into a vacuum bag using standard techniques and the assembly is evacuated for about 15 minutes at an absolute pressure of about 28 inches of Hg. After this degassing step, the vacuum bagged assembly is placed in an autoclave and heated and pressurized simultaneously to a temperature and pressure of 239°F and 100 psig, respectively, over a period of about 45 minutes. The laminate is held at these conditions for an additional 15 minutes to ensure that the polymer melts and bonds to the glass substrate. At the end of the hold time, the laminate is depressurized and cooled to ambient conditions to complete the lamination process.

[0078] The resulting laminate is substantially clear or transparent with little turbidity. The haze of the resulting laminate is measured using ASTM D1003, and as shown in Table 2, the haze of all laminates is 0.84%. The light transmittance of the resulting laminate is also measured using ASTM D1003. As shown in Table 2, the light transmittance of all laminates is 89.3.

[0079] Although the apparatus, system, and method have been described in detail herein in accordance with certain preferred embodiments, many modifications and changes can be made thereto by those skilled in the art. Accordingly, the foregoing description should not be construed as being limited thereby, but should be construed as including the foregoing obvious variations and being limited only by the spirit and scope of the following claims.

[0080] For example, in a first aspect, a first embodiment is an optical interlayer film comprising at least one surface having an embossed surface pattern with at least two channels extending in at least two non-parallel directions. The depth of the channels is greater than about 20 μm.

[0081] A second embodiment is the first embodiment, wherein the depth of the channels is greater than about 30 μm.

[0082] A third embodiment is any combination of the previous 2 embodiments, wherein the depth of the channels is from about 30 μm to about 50 μm.

[0083] A fourth embodiment is any combination of the previous 3 embodiments, wherein the depth of the channels is from about 35 μm to about 43 μm.

[0084] A fifth embodiment is any combination of the previous 4 embodiments, wherein the width of the channels is from about 30 μm to about 900 μm.

[0085] A sixth embodiment is any combination of the previous 5 embodiments, wherein the channels are formed by one or more protrusions extending from the surface and one or more depressions extending into the surface, and the distance between the peak of the protrusion and the lowest point of the depression is greater than about 20 μm.

[0086] A seventh embodiment is any combination of the previous 6 embodiments, wherein the width of the channels is from about 400 μm to about 600 μm.

[0087] An eighth embodiment is any combination of the previous 7 embodiments, wherein the film comprises a non-plasticized thermoplastic material.

[0088] A ninth embodiment is any combination of the previous 8 embodiments, wherein the film comprises thermoplastic polyurethane (TPU).

[0089] A tenth embodiment is any combination of the previous 9 embodiments, wherein the film comprises ethylene vinyl acetate (EVA).

[0090] An eleventh embodiment is any combination of the previous 10 embodiments, further comprising a second surface opposite the first surface, wherein the second surface has an embossed surface pattern with at least two channels extending in at least two non-parallel directions, and the depth of the channels is greater than about 20 μm.

[0091] A twelfth embodiment is any combination of the previous 11 embodiments, wherein the thickness of the film is less than about 0.08 inches.

[0092] A thirteenth embodiment is any combination of the previous 12 embodiments, wherein the thickness of the film is less than about 0.02 inches.

[0093] The 14th embodiment is any combination of the first 13 embodiments, wherein the two channels are substantially perpendicular to each other.

[0094] The 15th embodiment is any combination of the first 14 embodiments, further comprising a first set of channels extending in a first direction and a second set of channels extending in a second direction not parallel to the first direction, wherein the channels within the first set of channels are spaced apart from each other by a distance of about 100 μm to about 1,000 μm.

[0095] In another aspect, there is provided a laminate comprising a film according to any combination of the first 15 embodiments.

[0096] In another aspect, there is provided a glass comprising a film according to any combination of the first 15 embodiments.

[0097] In another aspect, there is provided a window glass comprising a film according to any combination of the first 15 embodiments.

[0098] In another aspect, the first embodiment is a laminate comprising at least one layer of glass; and an interlayer film comprising at least one surface having an embossed surface pattern, the embossed pattern having at least two channels extending in at least two non-parallel directions. Before lamination, the depth of the channels is greater than about 20 μm.

[0099] The second embodiment is the first embodiment, wherein the depth of the channels is greater than about 30 μm.

[0100] The third embodiment is any combination of the first 2 embodiments, wherein the depth of the channels is about 30 μm to about 50 μm.

[0101] The 4th embodiment is any combination of the first 3 embodiments, wherein the depth of the channels is about 35 μm to about 43 μm.

[0102] The 5th embodiment is any combination of the first 4 embodiments, wherein the laminate has a haze of about 0.8% to about 0.9% as measured by ASTM D1003.

[0103] The 6th embodiment is any combination of the first 5 embodiments, wherein the laminate has a light transmittance of about 85% to about 90% as measured by ASTM D1003.

[0104] The 7th embodiment is any combination of the first 6 embodiments, further comprising a second layer of glass, wherein the interlayer film is located between the first layer of glass and the second layer of glass.

[0105] The eighth embodiment is any combination of the first seven embodiments, wherein the film further comprises a second surface opposite the first surface, wherein the second surface has an embossed surface pattern having at least two channels extending in at least two non-parallel directions, and the depth of the channels is greater than about 20 μm.

[0106] The ninth embodiment is any combination of the first eight embodiments, wherein the film comprises a non-plasticized thermoplastic material.

[0107] The tenth embodiment is any combination of the first nine embodiments, wherein the film comprises thermoplastic polyurethane (TPU).

[0108] The eleventh embodiment is any combination of the first ten embodiments, wherein the film comprises ethylene vinyl acetate (EVA).

[0109] The twelfth embodiment is any combination of the first eleven embodiments, wherein the two channels are substantially perpendicular to each other.

[0110] The thirteenth embodiment is any combination of the first twelve embodiments, further comprising a first set of channels extending in a first direction and a second set of channels extending in a second direction non-parallel to the first direction, wherein the channels within the first set of channels are spaced apart from each other by a distance of about 100 μm to about 1,000 μm.

[0111] The fourteenth embodiment is any combination of the first thirteen embodiments, wherein the laminate comprises a safety glass laminate.

[0112] In another aspect, there is provided a glass comprising a laminate of any combination of the first fourteen embodiments.

[0113] In another aspect, there is provided a window glass comprising a laminate of any combination of the first fourteen embodiments.

[0114] In another aspect, the first embodiment is a method of producing an interlayer film. The method includes forming an embossed pattern on a calender roll and transferring the embossed pattern to the surface of the interlayer film such that the surface has at least two channels extending in at least two non-parallel directions. The depth of the channels is greater than about 20 μm.

[0115] The second embodiment is the first embodiment, wherein the interlayer film comprises a second surface opposite the first surface, and the method further includes transferring the embossed pattern to the second surface.

[0116] The third embodiment is any combination of the first two embodiments, further comprising placing an optical interlayer film between a first sheet and a second sheet of glass to obtain a laminated structure, and subjecting the laminated structure to vacuum lamination.

[0117] The fourth embodiment is any combination of the first three embodiments, wherein the calender roll is a metal roll.

[0118] The fifth embodiment is any combination of the first five embodiments, wherein the depth of the channel is greater than about 30 μm.

[0119] The sixth embodiment is any combination of the first five embodiments, wherein the depth of the channel is from about 35 μm to about 43 μm.

[0120] The seventh embodiment is any combination of the first six embodiments, wherein the sandwich film comprises a non-plasticized thermoplastic material.

[0121] The eighth embodiment is any combination of the first seven embodiments, wherein the sandwich film comprises thermoplastic polyurethane (TPU).

[0122] The ninth embodiment is any combination of the first eight embodiments, wherein the film comprises ethylene vinyl acetate (EVA).

[0123] In another aspect, there is provided a sandwich film formed from any combination of the first nine embodiments.

[0124] In another aspect, there is provided a laminate formed from any combination of the first nine embodiments. In another aspect, there is provided a window glass formed from any combination of the first nine embodiments.

Claims

1. An optical interlayer film comprising at least one surface having an embossed surface pattern, the embossed surface pattern having at least two channels extending in at least two non-parallel directions, the depth of the channels being greater than about 20 μm.

2. The film according to claim 1, wherein the depth of the channels is greater than about 30 μm.

3. The film according to claim 1, wherein the depth of the channels is from about 30 μm to about 50 μm.

4. The film according to claim 1, wherein the depth of the channels is from about 35 μm to about 43 μm.

5. The film according to claim 1, wherein the width of the channels is from about 30 μm to about 900 μm.

6. The film according to claim 1, wherein the channels are formed by one or more protrusions extending from the surface and one or more depressions extending into the surface, wherein the distance between the peaks of the protrusions and the lowest points of the depressions is greater than about 20 μm.

7. The film according to claim 1, wherein the width of the channels is from about 400 μm to about 600 μm.

8. The film according to claim 1, wherein the film comprises a non-plasticized thermoplastic material.

9. The film according to claim 1, wherein the film comprises thermoplastic polyurethane (TPU).

10. The film according to claim 1, wherein the film comprises ethylene vinyl acetate (EVA).

11. The film according to claim 1, further comprising a second surface opposite the first surface, wherein the second surface has an embossed surface pattern, the embossed surface pattern having at least two channels extending in at least two non-parallel directions, the depth of the channels being greater than about 20 μm.

12. The film according to claim 1, wherein the thickness of the film is less than about 0.08 inches.

13. The film according to claim 1, wherein the thickness of the film is less than about 0.02 inches.

14. The film according to claim 1, wherein the two channels are substantially perpendicular to each other.

15. The film according to claim 1, further comprising a first set of channels extending in a first direction and a second set of channels extending in a second direction non-parallel to the first direction, wherein the channels within the first set of channels are spaced apart by a distance of about 100 μm to about 1,000 μm.

16. A laminate comprising the film according to claim 1.

17. A glass comprising the film according to claim 1.

18. A window glass comprising the film according to claim 1.

19. A laminate comprising: at least one layer of glass; and an interlayer film comprising at least one surface having an embossed surface pattern, the embossed surface pattern having at least two channels extending in at least two non-parallel directions, the depth of the channels being greater than about 20 μm prior to lamination.

20. The laminate according to claim 19, wherein the depth of the channels is greater than about 30 μm.

21. The laminate according to claim 19, wherein the depth of the channels is from about 30 μm to about 50 μm.

22. The laminate according to claim 19, wherein the depth of the channels is from about 35 μm to about 43 μm.

23. The laminate according to claim 19, wherein the laminate has a haze of from about 0.8% to about 0.9% as measured by ASTM D1003.

24. The laminate according to claim 19, wherein the laminate has a light transmittance of from about 85% to about 90% as measured by ASTM D1003.

25. The laminate according to claim 19, further comprising a second glass layer, wherein the interlayer film is located between the first glass layer and the second glass layer.

26. The laminate according to claim 25, wherein the film further comprises a second surface opposite the first surface, wherein the second surface has an embossed surface pattern having at least two channels extending in at least two non-parallel directions, and the depth of the channels is greater than about 20 μm.

27. The laminate according to claim 19, wherein the film comprises a non-plasticized thermoplastic material.

28. The laminate according to claim 19, wherein the film comprises thermoplastic polyurethane (TPU).

29. The laminate according to claim 19, wherein the film comprises ethylene vinyl acetate (EVA).

30. The laminate according to claim 19, wherein the two channels are substantially perpendicular to each other.

31. The laminate according to claim 19, further comprising a first set of channels extending in a first direction and a second set of channels extending in a second direction non-parallel to the first direction, wherein the channels within the first set of channels are spaced apart from each other by a distance of from about 100 μm to about 1,000 μm.

32. The laminate according to claim 19, wherein the laminate comprises a safety glass laminate.

33. A glass comprising the laminate according to claim 19.

34. A window glass comprising the laminate according to claim 19.

35. A method of producing an interlayer film, which comprises: forming an embossed pattern on a calender roll; and transferring the embossed pattern to the surface of the interlayer film such that the surface has at least two channels extending in at least two non-parallel directions, and the depth of the channels is greater than about 20 μm.

36. The method according to claim 35, wherein the interlayer film comprises a second surface opposite the first surface, and the method further comprises transferring the embossed pattern to the second surface.

37. The method according to claim 35, further comprising placing an optical interlayer film between a first sheet and a second sheet of glass to obtain a laminated structure, and subjecting the laminated structure to vacuum lamination.

38. The method according to claim 35, wherein the calender roll is a metal roll.

39. The method according to claim 35, wherein the depth of the channels is greater than about 30 μm.

40. The method according to claim 35, wherein the depth of the channels is from about 35 μm to about 43 μm.

41. The method according to claim 35, wherein the interlayer film comprises a non-plasticized thermoplastic material.

42. The method according to claim 35, wherein the interlayer film comprises thermoplastic polyurethane (TPU).

43. The method according to claim 35, wherein the film comprises ethylene vinyl acetate (EVA).

44. An interlayer film formed by the method according to claim 35.

45. A laminate formed by the method according to claim 35.

46. A window glass formed by the method according to claim 35.

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