阅读说明：本技术 光学叠堆 (Optical stack ) 是由 米歇尔·L·托伊 克里斯蒂·A·吉勒特 马修·B·约翰逊 艾琳·M·弗雷尼 卡莉·A·哈罗德 于 2020-04-28 设计创作，主要内容包括：本发明公开了一种光学叠堆,该光学叠堆包括光学膜(200)和设置在该光学膜上的光学粘合剂(500)。该光学粘合剂具有背对该光学膜的主结构化表面,该主结构化表面包括形成于其中的多个通道。这些通道之间限定多个基本上平坦的台面区域。这些台面区域占该主结构化表面的总表面积的至少约50％。当该光学叠堆放置在支撑表面上且该光学粘合剂的该主结构化表面接触该支撑表面时,该光学叠堆粘结到该支撑表面并且能够在不损坏该光学粘合剂或该支撑表面的情况下从该支撑表面移除或以滑动的方式在该支撑表面上重新定位,并且在施加热和压力中的至少一者时,该光学叠堆基本上永久性地粘结到该支撑表面,并且该多个通道基本上消失。(An optical stack includes an optical film (200) and an optical adhesive (500) disposed on the optical film. The optical adhesive has a primary structured surface facing away from the optical film, the primary structured surface including a plurality of channels formed therein. The channels define a plurality of substantially planar mesa regions therebetween. The mesa regions comprise at least about 50% of the total surface area of the primary structured surface. When the optical stack is placed on a support surface with the primary structured surface of the optical adhesive contacting the support surface, the optical stack is bonded to the support surface and can be removed from or repositioned in a sliding manner on the support surface without damaging the optical adhesive or the support surface, and upon application of at least one of heat and pressure, the optical stack is substantially permanently bonded to the support surface, and the plurality of channels substantially disappear.)

1. An optical stack, comprising:

an optical film comprising a plurality of alternating first and second polymer layers in a total number of at least 50, each of the first and second polymer layers having an average thickness of less than about 500 nm; and

an optical adhesive disposed on the optical film and comprising a first major surface facing and bonded to the optical film and an opposing second major structured surface comprising a plurality of irregularly arranged intersecting channels formed therein, the channels defining therebetween a plurality of substantially planar land areas comprising at least about 50% of a total surface area of the second major structured surface such that when the optical stack is placed on a support surface with the second major structured surface of the optical adhesive in contact with the support surface, the optical stack is bonded to and can be removed from or repositioned in a sliding manner on the support surface without damaging the optical adhesive or the support surface, and upon application of at least one of heat and pressure, the optical stack is substantially permanently bonded to the support surface and the plurality of channels substantially disappear.

2. The optical stack of claim 1, wherein the optical adhesive has sound absorbing properties for reducing noise in the interior of a motor vehicle such that a ratio of a loss modulus G "to a storage modulus G' of the optical adhesive is greater than about 0.3 for frequencies in the range of about 1000Hz to about 3200 Hz.

3. The optical stack of claim 1 or 2, wherein each channel of the plurality of irregularly arranged intersecting channels is substantially straight.

4. The optical stack of any one of claims 1-3, wherein the optical film is a reflective polarizer or mirror.

5. The optical stack of any one of claims 1-4, wherein the optical adhesive comprises polyvinyl butyral, an acrylate, a thermoplastic polyurethane, ethylene vinyl acetate, or one or more combinations thereof.

6. The optical stack of any one of claims 1-5, wherein when the optical stack is placed on a support surface with the second primary structured surface of the optical adhesive in contact with the support surface and the optical adhesive is heated at a temperature of about 40 ℃ to 160 ℃ and subjected to a pressure of about 4 atmospheres to 12 atmospheres, the optical stack is substantially permanently bonded to the surface and the plurality of channels substantially disappear.

7. An optical stack, comprising:

an optical film; and

an optical adhesive adhered to the optical film and comprising a first major surface facing away from the optical film, the first major surface comprising a plurality of channels formed therein, each channel comprising a sidewall extending upwardly beyond a portion of the first major surface adjacent the channel to define a ridge substantially coextensive with the channel along at least a portion of the length of the channel such that when the optical stack is placed on a support surface with the first major surface of the optical adhesive contacting the support surface, the optical stack is bonded to the support surface and can be removed from or repositioned on the support surface in a sliding manner without damaging the optical adhesive or the support surface, and upon application of at least one of heat and pressure, the optical stack is substantially permanently bonded to the support surface and the plurality of channels and the ridges substantially disappear.

8. The optical stack of claim 7, wherein the optical film comprises a plurality of alternating first and second polymer layers that reflect and transmit light primarily by optical interference.

9. The optical stack of any of claims 1-6 or 8, wherein the first polymer layer has a first in-plane birefringence, the first in-plane birefringence being the difference between the refractive index of the first polymer layer along a first in-plane direction and the refractive index of the first polymer layer along an orthogonal second in-plane direction, and the second polymer layer has a second in-plane birefringence, the second in-plane birefringence being the difference between the refractive index of the second polymer layer along the first in-plane direction and the refractive index of the second polymer layer along the second in-plane direction, the second in-plane birefringence being less than the first in-plane birefringence and greater than 0.03.

10. The optical stack of claim 9, wherein the first polymer layer comprises a polyethylene terephthalate homopolymer and the second polymer layer comprises a glycol-modified co (polyethylene terephthalate).

11. An automotive windshield comprising an optical assembly disposed between and bonded to two glass substrates, the optical assembly prepared by: disposing the optical stack of any one of claims 1-10 between the two glass substrates and applying at least one of heat and pressure such that the optical adhesive is substantially permanently bonded to one of the two glass substrates and the plurality of channels substantially disappear.

12. An automotive windshield comprising an optical stack disposed between and bonded to an interior glass substrate and an exterior glass substrate, the optical stack comprising:

an optical film comprising a plurality of alternating first and second polymer layers in a total number of at least 50, each of the first and second polymer layers having an average thickness of less than about 500 nm; and

a first optical adhesive bonding the optical film to the interior glass substrate, the first optical adhesive having an average thickness in a range of about 10 microns to about 100 microns and having sound absorbing properties for reducing noise in an interior of a motor vehicle such that a ratio of a loss modulus G 'to a storage modulus G' of the optical adhesive is greater than about 0.3 for frequencies in a range of about 1000Hz to about 3200 Hz.

13. The automotive windshield according to claim 12, further comprising: a second optical adhesive bonding the optical film to the external glass substrate, the second optical adhesive having an average thickness that is at least twice an average thickness of the first optical adhesive.

14. A display system for displaying virtual images to an observer, the display system comprising:

a display configured to emit an image; and

a projection system comprising the automotive windshield according to any one of claims 11 to 13, the projection system forming a virtual image of the image emitted by the display for viewing by an observer.

15. The display system of claim 14, wherein the display comprises a liquid crystal display, an organic light emitting diode display, a laser display, a digital micromirror display, or a laser display.

Background

An automotive windshield may be a glass laminate that includes an optical film disposed between and bonded to two glass layers. The optical film may be a reflective polarizer for reflecting an image projected onto the windshield.

Disclosure of Invention

In some aspects of the present description, an optical stack is provided that includes an optical film and an optical adhesive disposed on the optical film. The optical film includes a plurality of alternating first and second polymer layers in a total number of at least 50, wherein the first and second polymer layers each have an average thickness of less than about 500 nm. The optical adhesive includes a first major surface facing and bonded to the optical film and an opposing second major structured surface including a plurality of irregularly arranged intersecting channels formed therein. The channels define a plurality of substantially planar mesa regions therebetween, wherein the mesa regions comprise at least about 50% of a total surface area of the second primary structured surface. When the optical stack is placed on a support surface with the second primary structured surface of the optical adhesive contacting the support surface, the optical stack is bonded to the support surface and can be removed from or repositioned in a sliding manner on the support surface without damaging the optical adhesive or the support surface, and upon application of at least one of heat and pressure, the optical stack is substantially permanently bonded to the support surface and the plurality of channels substantially disappear.

In some aspects of the present description, an optical stack is provided that includes an optical film and an optical adhesive adhered to the optical film. The optical adhesive includes a first major surface facing away from the optical film. The first major surface includes a plurality of channels formed therein, wherein each channel includes a sidewall that extends upwardly beyond a portion of the first major surface adjacent the channel to define a ridge that is substantially coextensive with the channel along at least a portion of the length of the channel. When the optical stack is placed on a support surface with the first major surface of the optical adhesive contacting the support surface, the optical stack is bonded to the support surface and can be removed from or repositioned in a sliding manner on the support surface without damaging the optical adhesive or the support surface, and upon application of at least one of heat and pressure, the optical stack is substantially permanently bonded to the support surface and the plurality of channels and ridges substantially disappear.

In some aspects of the present description, an automotive windshield is provided that includes an optical stack disposed between and bonded to an interior glass substrate and an exterior glass substrate. The optical stack includes an optical film comprising a plurality of alternating first and second polymer layers in a total number of at least 50, wherein the first and second polymer layers each have an average thickness of less than about 500 nm. The optical stack also includes a first optical adhesive bonding the optical film to the interior glass substrate, the first optical adhesive having an average thickness in a range of about 10 microns to about 100 microns and having sound absorption properties for reducing noise in the interior of the motor vehicle such that a ratio of a loss modulus G ″ to a storage modulus G' of the optical adhesive is greater than about 0.3 for frequencies in a range of about 1000Hz to about 3200 Hz.

Drawings

FIG. 1A is a schematic cross-sectional view of an optical stack;

fig. 1B-1C are schematic bottom views of optical stacks;

FIG. 2A is a schematic cross-sectional view of an optical adhesive;

fig. 2B is a schematic perspective view of a portion of a major surface of an optical adhesive;

FIG. 3A is a schematic cross-sectional view of an optical stack placed on a support surface;

FIG. 3B is a schematic cross-sectional view of an optical stack substantially permanently bonded to a support surface;

FIG. 4A is a schematic perspective view of an optical film;

FIG. 4B is a schematic perspective view of a section of the optical film of FIG. 4A;

FIG. 5 is a schematic cross-sectional view of a display system;

FIG. 6 is a plot of the ratio of loss modulus G 'to storage modulus G' versus frequency for various optical adhesives; and is

Fig. 7 is a graph of the auditory transmission loss through various glass laminates.

Detailed Description

In the following description, reference is made to the accompanying drawings, which form a part hereof and in which is shown by way of illustration various embodiments. The figures are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description is, therefore, not to be taken in a limiting sense.

Fig. 1A-1B are a schematic cross-sectional view and a schematic bottom view, respectively, of an optical stack 1000 including an optical film 200 and an optical adhesive 500 disposed on the optical film 200. The optical adhesive 500 includes a first major surface 512 that faces and is bonded to the optical film 200 and an opposing second major structured surface 514 that includes a plurality of irregularly arranged intersecting channels 520 formed therein. The optical adhesive typically has a high transmission to visible light (e.g., an average optical transmission of at least 70%, or at least 80%, or at least 90% over a wavelength range of 400nm to 700 nm) and low haze (e.g., a haze of less than 5%, or less than 3%, or less than 2%, or less than 1%). The transmission and haze can be determined, for example, as described in ASTM D1003-13 test Standard. The channels 520 define a plurality of substantially planar mesa regions 525 therebetween. Mesa region 525 comprises at least about 50% of the total surface area of second main structured surface 514. In some embodiments, when optical stack 1000 is placed on a support surface (e.g., a surface of a glass substrate) and second primary structured surface 514 of optical adhesive 500 contacts the support surface, optical stack 1000 is bonded to a support surface and can be removed from or repositioned on the support surface in a sliding manner without damaging optical adhesive 500 or the support surface, and upon application of heat and pressure (e.g., in some cases, both heat and pressure), optical stack 1000 is substantially permanently bonded to the support surface (e.g., to the extent that the optical stack and support surface are separated by peeling, e.g., would cause damage to at least one of the optical stack or support surface) and the plurality of channels substantially disappear (e.g., not visible to a person with 20/20 vision under ordinary daylight conditions). As further described elsewhere herein, the optical film 200 can include a plurality of alternating first and second polymer layers in a total number of at least 50, wherein the first and second polymer layers each have an average thickness of less than about 500 nm.

Fig. 1C is a schematic bottom view of optical stack 1000b, which corresponds to optical stack 1000 except that structured surface 514b of adhesive 500b includes different patterns of channels 520b and land areas 525 b. In some embodiments, the average channel length of channels 520b is less than the lesser of the width and length of optical stack 1000 b.

In some embodiments, each channel of the plurality of irregularly arranged intersecting channels is substantially straight. A channel may be described as substantially straight if any radius of curvature of a line or curve extending along the length of the channel is at least 3 times, or at least 5 times, or at least 10 times the length of the channel.

For example, the irregularly arranged channels may be randomly or pseudo-randomly arranged. The pseudo-random arrangement may appear random, but may have been formed by an underlying deterministic process.

For example, adhesive coated optical films can be prepared by coating directly onto the optical film or transfer coating/laminating onto the optical film.

In the case of direct coating, the substrate can be prepared by applying the adhesive to the optical film by known coating processes such as slot die, slot-fed knife coating, gravure coating, slide coating, or curtain coating, or other methods known in the art. The binder may be coated with solvent, water, or as a 100% solids formulation to produce a coating thickness in the range of 5 microns to 127 microns, for example. Suitable chemicals include radiation curable, thermoplastic or thermoset polymer formulations or combinations thereof. To aid in adhesion to the substrate, the optical film may be pre-treated with a primer coating or surface treatment (e.g., plasma, corona, flame) or other methods known in the art.

For transfer coating or laminating the adhesive to the optical film, the adhesive may first be coated onto the releasable substrate by a similar coating process as described elsewhere. The release substrate containing the adhesive can be laminated to the optical film under pressure and temperature such that the adhesive is completely transferred from the release substrate to the optical film upon removal of the release substrate. To aid in adhesion to the substrate, the optical film may be pre-treated with a primer coating or surface treatment (plasma, corona, flame) or other methods known in the art.

Fig. 2A is a schematic cross-sectional view of a portion of an optical adhesive 600 having a first major surface 614 (which may correspond to the second major structured surface 514, for example) that includes a plurality of channels therein (a single channel 620 is schematically illustrated for the portion shown in fig. 2A-2B). The plurality of channels may be a plurality of irregularly arranged intersecting channels as described elsewhere herein, or other channel geometries may be used (e.g., a periodic or aperiodic one-dimensional array of non-intersecting channels, or a periodic two-dimensional array of intersecting channels). Fig. 2B is a schematic perspective view of a portion of the first major surface 614. In some embodiments, each channel 620 includes a sidewall 622a (respectively 622b) that extends upwardly beyond a portion 614a (respectively 614b) of the major surface 614 to define a ridge 624a (respectively 624b) that is substantially coextensive with the channel 620 along at least a portion of the length of the channel 620 (e.g., extends along more than half, or more than 70%, or more than 80% of the length of the portion).

In this context, upward may be understood as relative to the channel: the ridges 624a and 624b are upward relative to the bottom portion of the channel 620. Such spatially relative terms, such as upward, encompass different orientations of the article in use or operation in addition to the particular orientation depicted in the figures and described herein.

In some embodiments, the optical stack includes an optical film and an optical adhesive 600 adhered to the optical film, with the first major surface 614 facing away from the optical film. For example, optical adhesive 600 can be used as optical adhesive 500 in optical stack 1000. In some embodiments, when the optical stack is placed on a support surface with first major surface 614 of optical adhesive 600 contacting the support surface, the optical stack is bonded to the support surface and can be removed from or repositioned in a sliding manner on the support surface without damaging optical adhesive 600 or the support surface, and upon application of at least one of heat and pressure, the optical stack is substantially permanently bonded to the support surface, and the plurality of channels 620 and ridges 624a, 624b substantially disappear.

Fig. 3A is a schematic cross-sectional view of optical stack 2000 placed on support surface 741. Optical stack 2000 includes optical film 300 and optical adhesive 700 (e.g., corresponding to optical adhesive 500 or 600). The support article 740 includes a support surface 741. The support article 740 may be, for example, a glass layer of an automotive windshield. Optical adhesive 700 has a structured major surface 714 having a plurality of channels 720 formed therein. The plurality of channels 720 may be a plurality of irregularly arranged intersecting channels as described elsewhere herein, or other channel geometries may be used. In the embodiment shown, each channel 720 includes sidewalls that extend upwardly beyond portions of the first major surface adjacent the channel to define ridges that may be substantially coextensive with the channel along at least a portion of its length. In fig. 3A, optical stack 2000 is bonded to support surface 741 and can be removed from support surface 741 or repositioned on the support surface in a sliding manner without damaging optical adhesive 700 or support surface 741. In some embodiments, upon application of at least one of heat and pressure, optical stack 2000 is substantially permanently bonded to support surface 714 and plurality of channels 720 and ridges 724 (when present in adhesive 70) substantially disappear. This is schematically illustrated in fig. 3B. Fig. 3B is a schematic cross-sectional view of optical stack 2001 substantially permanently bonded to support surface 741. Optical stack 2001 corresponds to optical stack 2000 and optical adhesive 701 corresponds to optical adhesive 700 after application of at least one of heat and pressure that causes channels 720 and ridges 724 to disappear from optical adhesive 701.

In some embodiments, an automotive windshield is formed by disposing the optical stack between two glass substrates, with the additional adhesive between the optical film and the glass substrate opposing the optical adhesive of the optical stack. The two glass substrates may be permanently bonded together by the application of heat and pressure in an autoclave process. In such embodiments, it is generally desirable for the channels to disappear or substantially disappear when the autoclave process is conducted.

In some embodiments, when the optical stack is placed on a support surface with the second primary structured surface of the optical adhesive in contact with the support surface and the optical adhesive is heated at a temperature of about 40 ℃ to 160 ℃ and subjected to a pressure of about 4 atmospheres to 12 atmospheres, the optical stack is substantially permanently bonded to the surface and the plurality of channels (and the plurality of ridges (in some embodiments where ridges are present)) substantially disappear.

The channels may be provided, for example, by: the adhesive, e.g., the release liner and adjacent release liner, is deformed using an embossing tool, or the release liner (which is then placed in direct contact with the adhesive layer) is embossed under heat and/or pressure to impart, e.g., a pattern in the adhesive. Alternatively, the adhesive may be coated directly onto the patterned liner and then laminated to the optical film. Additionally, channels can be imparted directly into the adhesive by: the adhesive is brought into contact with an embossing or pattern roll or an idler roll, after which a liner is applied to protect the resulting structure during rolling. When the adhesive layer is applied to a substrate, the rheology of the adhesive may be such that the plurality of channels substantially disappear upon application of heat and/or pressure. Methods for forming channels in an adhesive layer are generally described in, for example, U.S. patent applications 2003/0178124(Mikami et al), 2007/0212535(Sherman et al), 2016/0114568(Sher et al), 2016/0115356(Free), 2016/0130485(Free et al), 2017/0362469(Sherman et al), and 2018/0257346(Austin et al), as well as in, for example, International application publication 2019/193501(Wang et al).

The optical adhesive used in the optical stacks of the present description can be any suitable optical adhesive. In some embodiments, the optical adhesive comprises polyvinyl butyral, an acrylate, a thermoplastic polyurethane, ethylene vinyl acetate, or one or more combinations thereof. The thickness of the optical adhesive may be, for example, in the range of about 10 microns to about 100 microns, or in the range of about 20 microns to about 60 microns.

In some embodiments, an automotive windshield (see, e.g., fig. 5) includes an optical stack disposed between and bonded to two glass substrates. The optical adhesive of the optical stack (the first optical adhesive) can bond the optical film to an interior glass substrate (which faces the interior of the automobile) and the second optical adhesive can bond the optical film to an exterior glass substrate (which faces the exterior of the automobile). In some embodiments, the average thickness of the second optical adhesive is at least twice the average thickness of the first optical adhesive. In some embodiments, the optical stack includes an optical film (e.g., optical film 800) disposed between a first optical adhesive (e.g., optical adhesive 700) and a second optical adhesive (e.g., adhesive layer 655). In some embodiments, at least one of the first optical adhesive and the second optical adhesive has an outer surface that includes a channel as described elsewhere herein. In some embodiments, each of the first and second optical adhesives has an outer surface that includes a channel as described elsewhere herein. In some embodiments, at least one of the first optical adhesive and the second optical adhesive has a tan delta as described herein. In some embodiments, each of the first and second optical adhesives has a tan delta as described herein.

It has been found that the use of a first optical adhesive that is significantly thinner than a second optical adhesive reduces ghosting from multiple reflections in the windshield as further described in international application US2019/051733(VanDerlofske et al) and corresponding US provisional patent application 62/735567 entitled "Glass Laminate Including Reflective Film" filed 2018, 9, 24.

In some embodiments, the optical adhesive has sound absorbing properties for reducing noise in the interior of a motor vehicle such that the ratio of the loss modulus G "to the storage modulus G' of the optical adhesive is greater than about 0.3, or greater than about 0.4, or greater than about 0.5, or greater than about 0.8, or greater than about 1, or greater than about 1.2, or greater than about 1.5, or greater than about 1.7 for frequencies in the range of about 1000Hz to about 3200 Hz. In some such embodiments, the ratio, which may be referred to as tan δ (loss tangent), is no more than 4, or no more than 3.5, or no more than 3, over the frequency range. In some embodiments, this ratio is in the range of about 0.3 to about 4, or about 0.4 to about 4, or about 0.5 to about 3.5, or about 1 to about 3, in some embodiments, over the entire frequency range of about 1000Hz to about 3200 Hz. Fig. 6 is a plot of the ratio of loss modulus G "to storage modulus G' versus frequency for various optical adhesives described in the examples. The desired tan delta can be achieved by selecting an appropriate binder or by appropriately selecting the components of the binder (e.g., plasticizer content). tan delta can be measured according to, for example, ASTM D4065-12 test standard.

The optical film may be any suitable type of optical film. For example, the optical film may be a reflective polarizer or a mirror. In some embodiments, the optical film is an infrared reflector (e.g., reflects less than 20% of visible light and at least 80% of light in the 900nm to 1200nm wavelength range). In some embodiments, the optical film is an optical laminate comprising a visible light reflecting polarizer and an infrared reflector laminated together. The optical film can include, for example, alternating polymeric layers or alternating inorganic layers (e.g., on a polymeric substrate). In some embodiments, the optical film includes a reflective material vapor deposited onto a polymer film (e.g., PET). In some embodiments, the optical film is one or more of a reflective polarizer, a linear polarizer, or a circular polarizer. A linear polarizer may be converted to a circular polarizer by including a quarter-wave retarder, or vice versa. In some embodiments, the optical film comprises a liquid crystal-based polarizer. In some embodiments, the optical film includes a cholesteric liquid crystal layer.

The optical film may be a multilayer optical film that provides desired transmission and/or reflection characteristics at least in part by an arrangement of microlayers having different refractive indices. Such optical films have also been shown, for example, by coextrusion of alternating polymer layers. See, e.g., U.S. Pat. Nos. 3,610,729(Rogers), 4,446,305(Rogers et al), 4,540,623(Im et al), 5,448,404(Schrenk et al), and 5,882,774(Jonza et al). In such polymeric multilayer optical films, the polymeric materials are used primarily or exclusively in the preparation of the various layers. Such films are suitable for high-volume manufacturing processes and can be made into large sheets and rolls. In some embodiments, the optical film is described in, for example, international application publication WO2019/145860(Haag et al) or WO 2020/016703(Haag et al) or us provisional application 62/828632 filed 4/3 in 2019.

In automotive applications, a multilayer optical film can be laminated between glass layers using a polyvinyl butyral (PVB) adhesive layer under heat and pressure. The lamination process can result in a reduction in the flatness of the optical film, and this can result in waviness or wrinkles that are visible when viewing an image projected onto the glass laminate. It has been found that optical films laminated to a glass layer or between two glass layers can result in substantially reduced waviness when the optical film has a high shrinkage upon heating. For example, the optical film may have a shrinkage in the first direction of greater than 4%, or greater than 5%, or greater than 6%, or greater than 7%, or greater than 8% when heated at 150 ℃ for 15 minutes. The optical film may also have a shrinkage rate along a second direction orthogonal to the first direction of greater than 3%, or greater than 3.5%, or greater than 4%, or greater than 5%, or greater than 6%, or greater than 7%, or greater than 8% when heated at 150 ℃ for 15 minutes. The optical film may have a shrinkage rate of less than 20% along each of the first direction and the second direction when heated at 150 ℃ for 15 minutes. The first direction and the second direction may be understood as a direction in the plane of the optical film when the optical film is laid flat or a direction in a tangent plane at a certain position on the curved optical film. In some embodiments, the alternating layers have an in-plane birefringence that is the difference in refractive index along a first in-plane direction (e.g., the direction of orientation of the layers) and along an orthogonal second in-plane direction, and the first and second directions of specified shrinkage correspond to the first and second in-plane directions defining the in-plane birefringence. In some embodiments, the first direction is a first in-plane direction along the block axis of the reflective polarizer (the polarization axis along which the reflective polarizer has the highest reflectivity), and the second direction is a second in-plane direction along the pass axis of the reflective polarizer (the polarization axis along which the reflective polarizer has the lowest reflectivity). In some embodiments, the block and pass axes of the reflective polarizer are defined by alternating layers of the reflective polarizer, as follows: the block axis is the axis along which the refractive index difference between adjacent layers is greatest, and the pass axis is along the orthogonal in-plane direction. Methods of making multilayer Optical films having high shrinkage are further described elsewhere herein and in PCT publication WO 2017/205106 (storer et al) and corresponding U.S. patent application publication 2019/0196076 (storer et al) and U.S. provisional patent application 62/828632 entitled "Optical Film and Glass Laminate" (Optical Film and Glass Laminate) filed on 3.4.2019.

It has also been found that optical films (e.g., reflective polarizers) having both high and low refractive index layers with a degree of crystallinity formed during stretching, for example, due to the low stretching temperature of polyethylene terephthalate, are particularly useful in, for example, automotive applications. In addition, optical films such as multilayer reflective polarizers in which both a high refractive index layer and a low refractive index layer are stretched to form an asymmetric refractive index have been found to be useful in automotive or other applications. For example, such films have been found to exhibit better haze suppression after exposure to heat (e.g., in an automobile exposed to sunlight), as further described in PCT publication WO2019/145860 (hag et al) and in corresponding us provisional patent application 62/622526 entitled "Multilayer Reflective Polarizer with Crystalline Low Index layer (multi layer Reflective polarizers with Crystalline Low Index Layers)" filed on day 26 of 2018.

Fig. 4A is a schematic perspective view of an optical film 100, which may be a reflective polarizer and which may be used in any of the glass laminates described elsewhere herein. Fig. 1B is a schematic perspective view of a section of optical film 100. Optical film 100 includes a plurality of layers 102 having a total of (N) layers. These layers may be or include a plurality of alternating polymeric interference layers. Fig. 1B shows alternating higher index layers 102a (a layers) and lower index layers 102B (B layers). The higher index layer has a refractive index in at least one direction that is greater than the refractive index of the lower index layer in the same direction. The higher refractive index layer 102a may be referred to as a first layer, and the lower refractive index layer 102b may be referred to as a second layer.

In some embodiments, the plurality of alternating first polymer layers 102a and second polymer layers 102b comprises less than about 900 layers, or less than about 500 layers, or less than about 300 layers. In some embodiments, the plurality of alternating first and second polymer layers 102a, 102b comprises at least about 50 layers, or at least about 100 layers, or at least about 200 layers, or a total number of layers (N) in a range of, for example, about 200 layers to about 300 layers. In some embodiments, the average thickness t of the optical film 100 is less than about 500 microns, or less than about 200 microns, or less than about 100 microns, or less than about 50 microns. The average thickness refers to an average value of the thickness over the entire area of the optical film. In some embodiments, the thickness is substantially uniform such that the thickness of the optical film is substantially equal to the average thickness t. In some embodiments, the optical film is shaped into a curved shape and has a thickness variation resulting from the shaping process. In some embodiments, each polymer layer 102 has an average thickness of less than about 500 nm.

During use, light incident on a major surface of optical film 100 (e.g., film surface 104), as indicated by incident light 110, can enter the first layer of optical film 100 and propagate through the plurality of interference layers 102, undergoing selective reflection or transmission by optical interference, depending on the polarization state of incident light 110. The incident light 110 may include a first polarization state (a) and a second polarization state (b) that are mutually orthogonal to each other. In some embodiments, optical film 100 is a reflective polarizer, and the first polarization state (a) can be considered a "pass" state and the second polarization state (b) can be considered a "block" state. In some embodiments, optical film 100 is a polarizer that is oriented along stretch axis 120 and not oriented along orthogonal axis 122. In such embodiments, the polarization state of normally incident light having an electric field along axis 122 is the first polarization state (a), and the polarization state of normally incident light having an electric field along axis 120 is the second polarization state (b). The axis 122 may be referred to as a pass axis and the axis 120 may be referred to as a block axis. In some embodiments, as incident light 110 propagates through the plurality of interference layers 102, a portion of the light in the second polarization state (b) is reflected by adjacent interference layers, resulting in the second polarization state (b) being reflected by the optical film 100, while a portion of the light in the first polarization state (a) passes entirely through the optical film 100.

In some embodiments, optical film 100 has a first average reflectivity for a first polarization state at a predetermined angle of incidence (e.g., an angle of incidence of a light ray relative to the surface normal) over a predetermined range of wavelengths (e.g., a visible wavelength range of 400nm to 700nm or other visible wavelength ranges described elsewhere herein) and a second average reflectivity for a second, orthogonal polarization state over the predetermined range of wavelengths at the predetermined angle of incidence, where the second average reflectivity is greater than the first average reflectivity, for example, in some embodiments, the second average reflectivity is at least 20% and the first average reflectivity is less than 15%. in some embodiments, optical film 100 is a reflective polarizer having an average reflectivity of at least 20% for normally incident light within the predetermined range of wavelengths polarized along the block axis, and has an average reflectivity of less than 15% for normally incident light within a predetermined wavelength range polarized along the pass axis. In some embodiments, the average reflectivity of normally incident light within the predetermined wavelength range polarized along the block axis is in the range of 25% to 75%. In some embodiments, the average reflectivity of normally incident light within the predetermined wavelength range polarized along the pass axis is less than 10%.

When the reflectivity and transmissivity of an interference layer can be reasonably described by optical interference or modeled reasonably accurately by optical interference, the interference layer or microlayer can be described as reflecting light and transmitting light primarily by optical interference. When the combined optical thickness (in the case of a reflective polarizer, the refractive index along the block axis multiplied by the physical thickness) of a pair of adjacent interference layers having different refractive indices is the wavelength of the light¹/₂They reflect light by optical interference. The interference layer typically has a physical thickness of less than about 500nm, or less than about 300nm, or less than about 200 nm. In some embodiments, each polymeric interference layer has an average thickness (an unweighted average of the physical thickness across the layer) in a range from about 45 nanometers to about 200 nanometers. The non-interference layer has an optical thickness that is too great to facilitate reflection of visible light by interference. The non-interference layer typically has a physical thickness of at least 1 micron or at least 5 microns. The interference layer 102 may be a plurality of polymeric interference layers that reflect light and transmit light primarily by optical interference within a predetermined wavelength range. Light comprising an interference layer and a non-interference layerThe average thickness of the optical film may be less than about 500 microns.

In some embodiments, optical film 100 includes a plurality of alternating first layers 102a and second layers 102b, first layers 102a having a first in-plane birefringence that is the difference between the refractive index of first layers 102a along first in-plane direction 120 and the refractive index of first layers 102a along second in-plane direction 122, and second layers 102b having a second in-plane birefringence that is the difference between the refractive index of second layers 102b along first in-plane direction 120 and the refractive index of second layers 102b along second in-plane direction 122. In some embodiments, the second in-plane birefringence is less than the first in-plane birefringence and greater than 0.03. In some embodiments, each first layer 102a has the same refractive index along the first in-plane direction and the second in-plane direction and along the thickness direction as each other first layer 102 a. In some embodiments, each second layer 102b has the same refractive index along the first in-plane direction and the second in-plane direction and along the thickness direction as each other second layer 102 b. In some embodiments, optical film 100 is a reflective polarizer comprising a plurality of alternating first and second layers 102a and 102b, wherein first layer 102a comprises a polyethylene terephthalate homopolymer and second layer 102b comprises a glycol-modified co (polyethylene terephthalate). In some embodiments, each first layer 102a is a polyethylene terephthalate homopolymer layer, and each second layer 102b is a glycol-modified co (polyethylene terephthalate) layer. In some embodiments, the optical film 100 has a shrinkage rate along the first in-plane direction 120 (or block axis 120) of greater than 4% and a shrinkage rate along the second in-plane direction 122 (or pass axis 122) of greater than 3% when heated at 150 ℃ for 15 minutes. In some embodiments, the shrinkage along the first direction 120 is greater than 5%, or 6%, or 7%, or 8% when heated at 150 ℃ for 15 minutes. In some such embodiments or in other embodiments, the shrinkage along the second direction 122 is greater than 3.5%, or 4%, or 5%, or 6%, or 7%, or 8% when heated at 150 ℃ for 15 minutes. In some embodiments, the shrinkage rate along the first direction 120 and the shrinkage rate along the second direction 122 are each greater than 5%, or 6%, or 7%, or 8% when heated at 150 ℃ for 15 minutes. In some embodiments, the difference in refractive index between the first layer 102a and the second layer 102b along the first in-plane direction 120, Δ n1, is at least 0.03, and the difference in refractive index between the first layer 102a and the second layer 102b along the second in-plane direction 122, Δ n2, has an absolute value | Δ n2| that is less than Δ n 1.

In some cases, the microlayers or interference layers have a correspondence to¹/₄The thickness and refractive index values of the wavelength stack, i.e. arranged in optical repeating units or cells, each having two adjacent microlayers of equal optical thickness (f ratio 50%), such optical repeating units effectively reflect light by constructive interference, the wavelength λ of the reflected light being twice the overall optical thickness of the optical repeating units. The f-ratio is the ratio of the optical thickness of the first layer (assumed to be the higher refractive index layer) to the total optical thickness of the optical repeating units in the optical repeating units of the first and second layers. The f-ratio of the optical repeat units is generally constant or substantially constant throughout the thickness of the optical film, but may vary in some embodiments, as described, for example, in U.S. patent 9,823,395(Weber et al). The f-ratio of the optical film is the average (unweighted average) of the f-ratios of the optical repeat units. Other layer arrangements are also known, such as multilayer optical films having a dual microlayer optical repeat unit with an f-ratio different than 50%, or films where the optical repeat unit includes more than two microlayers. These optical repeat unit designs can be configured to reduce or increase certain higher order reflections. See, for example, U.S. Pat. Nos. 5,360,659(Arends et al) and 5,103,337(Schrenk et al). A thickness gradient along the film thickness axis (e.g., z-axis) can be used to provide a broadened reflection band, such as a reflection band that extends across the visible region of a human and into the near infrared region, such that the microlayer stack continues to reflect across the visible spectrum as the band shifts to shorter wavelengths at oblique angles of incidence. Sharpening the band edges (i.e., the wavelength transition between high reflection and high transmission) by adjusting the thickness gradient is discussed in U.S. Pat. No. 6,157,490(Wheatley et al).

The reflective and transmissive properties of the multilayer optical film are a function of the refractive indices of the respective microlayers and the thicknesses and thickness distributions of the microlayers. Each microlayer (at least at localized positions in the film) can pass an in-plane refractive index n_x、n_yAnd a refractive index n associated with a thickness axis of the film_zTo characterize. These indices of refraction represent the index of refraction of the material in question for light polarized along mutually orthogonal x, y and z axes, respectively. For ease of description in this patent application, unless otherwise indicated, the x, y and z axes are assumed to be local Cartesian coordinates for any point of interest on the multilayer optical film, wherein the microlayers extend parallel to the x-y plane, and wherein the x axis is oriented in-plane of the film to maximize Δ n_xThe magnitude of (c). In these coordinates, Δ n_yCan be equal to or less than (but not greater than) Δ n_xThe magnitude of (c). In addition, which material layer is selected (to start calculating the difference Δ n)_x、Δn_y、Δn_z) By specifying Δ n_xIs determined to be non-negative. In other words, the difference in refractive index between the two layers forming the interface is Δ n_j＝n_1j–n_2jWherein j is x, y or z, and wherein the layer numbers 1, 2 are selected such that n_1x≥n_2xI.e. Δ n_x≥0。

In practice, the refractive index is controlled by judicious choice of materials and processing conditions. Conventional multilayer films are prepared by: a large number (e.g., tens or hundreds) of layers of two alternating polymers a, B are coextruded, possibly followed by passing the multilayer extrudate through one or more multiplication dies, and then stretching or otherwise orienting the extrudate to form the final film. The resulting film is typically composed of many-hundreds or hundreds-of individual microlayers whose thicknesses and refractive indices are tailored to provide one or more reflection bands in a desired spectral region, such as the visible or near infrared region. To achieve the desired reflectivity with the appropriate number of layers, adjacent microlayers typically exhibit a refractive index difference (Δ n) of at least 0.03 or at least 0.04 for light polarized along the x-axis_x). In some embodiments, the materials are selected such that for light polarized along the x-axisThe refractive index difference of (a) is as high as possible after orientation. If reflectivity for two orthogonal polarizations is desired, adjacent microlayers can also be made to exhibit a refractive index difference (Δ n) of at least 0.03 or at least 0.04 for light polarized along the y-axis_y)。

In certain embodiments, the multilayer reflective polarizer may be used in automotive applications. For example, a multilayer reflective polarizer may be used on or near at least a portion of a vehicle windshield. This application is significantly different from conventional liquid crystal display applications, since for safety reasons the driver should still be able to observe the road or surroundings through the multilayer reflective polarizer. In addition, other drivers should not be dazzled or have impaired vision due to the bright reflection of the driver's windshield. Highly reflective (for one polarization state), high performance conventional reflective polarizers will not achieve these desired characteristics.

In addition, previously known reflective polarizers are sensitive to automotive components and processing and environmental exposure involved in general use. For example, a reflective polarizer can be used with, processed with, or laminated to polyvinyl butyral (PVB) to achieve safe glass shatter resistance. Under high temperature processing used to form laminated windshield components, components having PVB-based materials can penetrate and degrade conventionally manufactured and designed reflective polarizers. As another example, polyethylene naphthalate, particularly polyethylene naphthalate (PEN) including NDC (dimethyl 2, 6-naphthalate), used as a polymer and/or copolymer in many commercially available reflective polarizers, can yellow when exposed to ultraviolet radiation. The vehicle environment provides sufficient exposure to solar radiation that will degrade the reflective polarizer over time. In such ambient environments, spontaneous large-scale crystallization may also occur, thereby developing haze in the reflective polarizer. In some embodiments, the reflective polarizers described herein do not comprise polyethylene naphthalate. In some embodiments, the reflective polarizers described herein do not comprise naphthalene-2, 6-dicarboxylic acid. In some embodiments, the reflective polarizers described herein do not have a refractive index greater than 1.7 in any direction in any layer, as measured at 550 nm.

Multilayer optical films are typically formed from alternating layers of two different polymers. One layer is a layer that develops birefringence when oriented. Since almost all polymers used to form multilayer optical films increase in the average refractive index when stretched, the layer is also commonly referred to as a high refractive index layer (or high refractive index optical (HIO) layer). The other of the alternating polymer layers is typically an isotropic layer having a refractive index equal to or less than the refractive index of the high refractive index layer. For this reason, this layer is generally referred to as a low refractive index layer (or low refractive index optical (LIO) layer). Typically, the high index layer is crystalline or semi-crystalline, while the low index layer is amorphous. This is based at least on the following concept: in order to obtain a sufficiently high optical axis rejection (based on the mismatch between the high and low refractive index layers in a certain in-plane direction) and a sufficiently low transmission axis rejection (based on the match between the high and low refractive index layers in a second orthogonal in-plane direction), an amorphous material would be required.

It has now been found that multilayer reflective polarizers having both a high refractive index layer and a low refractive index layer with a degree of crystallinity that develops during stretching due to the low stretching temperature of polyethylene terephthalate are particularly useful for automotive applications. Thus, in some embodiments, the reflective polarizer includes a plurality of alternating first and second polymer layers, wherein each of the first and second polymer layers exhibits crystallinity. In addition, multilayer reflective polarizers in which both the high and low index optical layers are stretched to form asymmetric refractive indices have been found to be useful in automotive applications. In some implementations, each of the high and low index layers can form or have an in-plane birefringence of at least 0.03 or less than 0.04. The in-plane birefringence is the difference in refractive index between the in-plane orientation direction (generally, the direction in which the orientation layer has the highest refractive index) and the orthogonal in-plane direction. For example, for a film in the x-y plane oriented along the x-direction, the in-plane birefringence is n_x-n_y. In some embodiments, when heated at 150 ℃ for 15 minutesA reflective polarizer having a shrinkage in any range described elsewhere herein includes a plurality of alternating first and second polymer layers 102a, 102b, wherein each of the first and second polymer layers 102a, 102b has an in-plane birefringence of at least 0.03, the in-plane birefringence being the difference in refractive index of the layer along a first in-plane direction 120 and the refractive index of the layer along an orthogonal second in-plane direction 122. In some embodiments, the difference in refractive index between each of the first and second polymer layers is at least 0.03 or at least 0.04 (e.g., in the range of 0.03 or 0.04 to 0.1 or 0.15 or 0.25) for at least one in-plane direction. In some embodiments, the difference in refractive index along the first in-plane direction 120 between each of the first and second polymer layers, Δ n1, is at least 0.03, and the difference in refractive index along the second in-plane direction 122 between each of the first and second polymer layers 102a and 102b, Δ n2, has an absolute value | Δ n2| that is less than Δ n 1. In some embodiments, Δ n1 is at least 0.04. In some such embodiments, or in other embodiments, | Δ n2| is less than 0.04, or less than 0.03, or less than 0.02. The refractive index was determined at a wavelength of 532nm, unless otherwise indicated.

During certain intermediate stretching steps, certain multilayer optical films may have similar birefringence characteristics; however, these films are then subjected to a heat-setting treatment that minimizes birefringence in at least one of the layers (typically the low refractive index layer or isotropic layer), thereby maximizing the block axis (stretch axis) reflectivity, which means that the final film (i.e., either a roll-form film or a converted film) does not exhibit these properties. In some embodiments, the optical film or reflective polarizer has at least four edges (e.g., a final film in roll form or a converted film having at least four edges). In some embodiments, the high index layer is selected to be polyethylene terephthalate (PET) and the low index layer is selected to be a copolyester of polyethylene terephthalate with cyclohexanedimethanol (PETG, such as available from Eastman Chemicals, Knoxville, Tenn.) as a glycol modifier. In some embodiments, the high index layer is selected to be PET and the low index layer is selected to be a 50:50 (by weight) blend of PETG and PCTG (again polyethylene terephthalate with cyclohexanedimethanol used as a glycol modifier, but with twice as much modifier as PETG, available from eastman chemical company, noksville, tennessee). In some embodiments, the high refractive index layer is selected to be PET and the low refractive index layer is selected to be a 33:33:33 (by weight) blend of PETG, PCTG and an "80: 20" copolyester derived from 40 mol% terephthalic acid, 10 mol% isophthalic acid, 49.75 mol% ethylene glycol and 0.25 mol% trimethylpropanol. Other copolyesters may be used as or in the low refractive index layers described herein. In some embodiments, an optical film, such as a reflective polarizer, includes alternating first and second layers, where each first layer comprises a polyethylene terephthalate homopolymer and each second layer comprises a glycol-modified co (polyethylene terephthalate). For example, in some embodiments, each second layer comprises a glycol-modified co (polyethylene terephthalate) including a first glycol-modified co (polyethylene terephthalate) and optionally a second, different glycol-modified co (polyethylene terephthalate). In some embodiments, each second layer further comprises a copolyester different from the first glycol-modified co (polyethylene terephthalate) and the second glycol-modified co (polyethylene terephthalate).

Reflective polarizers or other optical films comprising materials such as the exemplary groups described above have been found to exhibit better suppression of haze after high temperature exposure, since crystallization is gradually formed during processing, rather than spontaneously (with larger crystallization sites) during exposure to radiation or heat. Furthermore, with the combination of crystalline materials exemplified herein, appearance and appearance problems (such as wrinkling or delamination) appear to occur significantly less frequently. Reflective polarizers having crystallinity in both the high and low index layers also perform better in terms of chemical resistance and permeability (edge-encroachment) of other materials. The benefits of the material combinations described herein are further described in PCT publication WO2019/145860(Haag et al).

The optical films of the present description may have greater shrinkage than conventional multilayer optical films. If found, the optical film is laminated to or between glass layers such that high shrinkage (e.g., greater than 3% shrinkage in each of two orthogonal in-plane directions, and greater than 4% shrinkage in at least one in-plane direction) can significantly reduce or prevent distortion (e.g., wrinkles) in the optical film during lamination. Shrinkage can be controlled by controlling the stress during cooling of the film after stretching. It has generally been found that higher stresses during this cooling result in greater shrinkage. In some embodiments, heat setting is applied after the film is stretched. Heat setting can be performed in the final zone of a tenter oven used to orient the film as described in U.S. patent 6,827,886(Neavin et al). Typically, such heat-setting treatments are used in order to reduce or minimize the shrinkage of the film when heat is subsequently applied to the film. When it is desired to minimize the subsequent shrinkage of the film, the heat-set temperature may be set to the highest temperature that does not cause film breakage in the tenter, and the film may relax in the transverse direction near the heat-set zone, which reduces the film tension. Higher shrinkage, particularly in the machine direction (typically along the transmission axis when the optical film is a reflective polarizer), can be achieved by lowering the heat-setting temperature, by shortening the duration of the heat-setting treatment at a given heat-setting temperature, and/or by eliminating the heat-setting step. Higher shrinkage, particularly in the transverse direction (typically along the block axis when the optical film is a reflective polarizer), can be achieved, thereby reducing relaxation of the film in the block direction. This can be accomplished, for example, by adjusting the spacing between the tenter rails after heat setting. Reducing this spacing is often referred to as toe-in. The effect of heat-set temperature and internal restraint on film shrinkage is described in U.S. Pat. No. 6,797,396(Liu et al). Thus, by controlling the heat-set and toe-in conditions, the desired cross-directional shrinkage (e.g., greater than 4%, or greater than 5%, or greater than 6%, or greater than 7%, or greater than 8%, and in some embodiments, less than 20%, or less than 15%) and machine direction shrinkage (e.g., greater than 3%, or greater than 3.5%, or greater than 4%, or greater than 5%, or greater than 6%, or greater than 7%, or greater than 8%, and in some embodiments, less than 20%, or less than 15%, or less than 12%) can be achieved when the optical film is heated at 150 ℃ for 15 minutes. Shrinkage of the optical device can be measured according to, for example, ASTM D2732-14 Test Standard "Standard Test Method for unconstrained Linear Thermal Shrinkage of Plastic films and sheets" (Standard Test Method for Unrestrained Linear Shrinkage of Plastic films and sheets) ".

Optical films such as reflective polarizers described herein may also have an f-ratio greater than 0.5. In some embodiments, the f-ratio may be at least 0.55, at least 0.6, at least 0.65, at least 0.7, at least 0.75, at least 0.8, or at least 0.85. The transition of f-ratio higher than 0.5 attenuates the first order reflection band of the multilayer reflective polarizer, thereby favoring higher order reflection bands, thereby effectively reducing the reflectivity of the polarizer for the design wavelength range. For f-ratios below 0.5, similar optical effects are observed; for example, the f-ratio is less than 0.45, less than 0.4, less than 0.35, less than 0.3, less than 0.25, less than 0.2, or even less than 0.15. In addition to the lower birefringence developed from stretched PET (as compared to PEN or coPEN), these reflective polarizers may need to include more layers to achieve the desired level of reflectivity. Counterintuitively, in some embodiments, this is a design feature. For weakly reflective polarizers, microlayer thickness variations can have a large and disproportionate effect on the overall spectrum of the film. By making each individual microlayer pair weaker, a layer that enhances and overlaps the reflection bands of adjacent microlayer pairs can be added to the design. This smoothes the spectrum and achieves more consistent performance regardless of position on the web of film or even between rolls. The optical films described herein can have at least 50 layers, at least 100 layers, at least 150 layers, at least 200 layers, or at least 250 layers.

The reflective polarizers or other optical films described herein can have haze resistance even after exposure to heat. In some embodiments, the reflective polarizer may have a haze of no more than 1% when measured after 100 hours of exposure to 85 ℃, 95 ℃, or even 105 ℃. In some embodiments, the reflective polarizer may have a haze of no more than 2% after 100 hours of exposure to 105 ℃ or even 120 ℃. In some embodiments, the reflective polarizer may have a haze of no more than 3% or 3.5% after exposure to 120 ℃ for 100 hours. In some embodiments, the transmittance of these reflective polarizers may be unaffected or substantially unaffected by even short exposure to high temperatures (such as in an annealing step). In some embodiments, the transmission spectrum from 400nm to 800nm does not decrease by more than 10% or even by more than 5% after a 30 second annealing step at 232 ℃ (450 ° f).

Fig. 5 is a schematic cross-sectional view of a display system 5000 for displaying a virtual image 777 to an observer 780. An automotive windshield 9000 comprises an optical assembly 8000 disposed between and bonded to two glass substrates 721, 725. The optical assembly 8000 includes an optical film 800 and a (first) optical adhesive 700. For example, optical component 8000 can correspond to any of the optical stacks described elsewhere herein after the channels (and ridges, in some embodiments, when initially present) in optical adhesive 700 are substantially removed during lamination of an automotive windshield. The optical assembly 8000 is bonded to the inner glass substrate 721 by a first optical adhesive 700 and to the outer glass substrate 725 by an adhesive layer 655, which may be referred to as a second optical adhesive 655.

In some embodiments, an automotive windshield 9000 comprises an optical assembly 8000 disposed between and bonded to two glass substrates 721, 725. The optical component 8000 may be prepared by: any optical stack described elsewhere herein is disposed between two glass substrates, and at least one of heat and pressure is applied, such that the optical adhesive 700 is substantially permanently bonded to one (721) of the first glass substrate 721 and the second glass substrate 725, and the plurality of channels substantially disappear. An adhesive layer 655 may be disposed between the optical stack and the glass substrate 725, or the optical stack may further include an adhesive layer 655 opposite the optical adhesive of the optical stack such that the optical stack is substantially permanently bonded to the first and second glass substrates.

Display system 5000 also includes a display 722 configured to emit an image 123, and a projection system 4000 including an optical component 8000 and/or an automotive windshield 9000 including optical component 8000. Projection system 4000 forms a virtual image 777 of image 123 emitted by display 722 for viewing by observer 780.

In some embodiments, the display 722 is or includes a liquid crystal display, an organic light emitting diode display, a laser display, a digital micromirror display, or a laser display. Useful displays and display systems include those described in, for example, U.S. patent application publications 2015/0277172(Sekine), 2003/0016334(Weber et al), 2005/0002097(Boyd et al), 2005/0270655(Weber et al), 2007/0279755(Hitschmann et al), and 2012/0243104(Chen et al), as well as in, for example, U.S. patent 5,592,188(Doherty et al).

In some embodiments, optical component 8000 or any of the optical stacks described elsewhere herein include additional layers or elements. For example, additional layers or elements may be disposed between the optical film and the optical adhesive of the optical stack, or additional layers or elements may be disposed on the optical film opposite the optical adhesive. The layer or element may be an optical layer or optical coating (e.g., bragg grating) or an additional optical film such as an infrared mirror film, or may be at least one of a heating element or a heat sink layer. For example, the optical assembly 8000 may include at least one of a heating element or a heat dissipation layer, and the display system 5000 may include a thermal control system for deicing or defogging an automobile windshield 9000.

In some embodiments, the additional layer or element is or includes a diffraction grating such as a bragg grating. For example, waveguides used in head-up displays (HUDs) may utilize gratings as described, for example, in U.S. patent application publications 2015/0160529(Popovich et al), 2018/0074340(Robbins et al), and 2018/0284440(Popovich et al), or, for example, in U.S. patent 9,715,110(Brown et al).

In some embodiments, the additional element or layer is at least one of a heating element or a heat dissipation layer. For example, in embodiments where the heating element is located at the periphery of the windshield, the heating element may be used to defog or de-ice the windshield, and the heat dissipation element may be used to spread heat across a larger area of the windshield. In some embodiments, the additional layer or element is a resistive heating element that can substantially transmit normally incident visible light (e.g., transmit at least 60% of normally incident light in the 400nm to 700nm wavelength range). In some embodiments, the additional layer or element is a resistive heating element, and the resistive heating element and the optical film are each substantially transmissive in a predetermined radio frequency range (e.g., in the range of 3kHz or 30kHz to 30GHz or 3 GHz). Windshields with heating elements are known in the art and are described, for example, in U.S. Pat. Nos. 2,526,327(Carlson), 5,434,384(Koontz), 6,180,921(Boaz), 8,921,739(Petrenko et al) and in U.S. patent applications 2008/0203078(Huerter) and 2011/0297661(Raghavan et al).

In some embodiments, the optical stack includes at least one of a heating element or a heat spreading layer. In some embodiments, at least one of the heating element or the heat spreading layer comprises one or more resistive elements, which may comprise, for example, wires, nanowires (e.g., silver nanowires), or Indium Tin Oxide (ITO). In some embodiments, at least one of the heating element or the heat spreading layer comprises a heat spreading layer, which may comprise, for example, nanowires, carbon nanotubes, graphene, or graphite. In some embodiments, the optical stack includes a heat spreading layer covering a majority of the total area of the major surfaces of the optical film.

Heating elements, heat dissipating elements, and automotive thermal control systems utilizing such elements are further described in U.S. provisional patent application No. 62/828632 entitled "Optical Film and Glass Laminate" filed on 3.4.2019.

Examples

Preparation of gasket example P1 (85% plane)

Liner L1 (the liner being a pellet filled press)Printed release liner) was prepared as described in table 1, column 11 of U.S. patent 5,296,277(Wilson et al), wherein the surface depression was 7225/inch²And a density of 85 threads/inch. Liner F1 was a 46um thick plasticized, white flexible and conformable vinyl (PVC) Film for 3M Print Wrap Film IJ180C-10 available from 3M Company (st. paul, MN) of st paul, minnesota.

The pattern was embossed into the release liner L1 by passing the release liner between a silicone rubber roller and an engraved metal roller. This produced an irregular channel embossed release liner. The engraved pattern is a series of recessed lines (channels) placed pseudo-randomly (irregularly) on the surface of the engraved roller so that the ratio of the planar area to the total surface area is 85%. For clarity, pseudo-random patterning in this context is patterning that may appear random by casual observation, but repetitive features will be noted upon careful observation. In this case, 8 discrete planar orientations (11 degrees, 73 degrees, 53 degrees, 23 degrees, 17 degrees, 71 degrees, 47 degrees, and 29 degrees from the crossweb orientation) were used to place individual lines that were about 30 microns deep by 60 microns wide at the center of the channel, tapering to zero in depth and width at the ends. The wire is about 4.3mm (+/-0.2mm) long. The pattern of lines is generally as shown in figure 1C. The tapered profile (in cross-section) is a continuous arch with a maximum depth to width ratio defined by the arch having a radius of 21.3 microns transitioning across a width of 59.2 microns to a sidewall draft angle of 60 degrees. The channel cross-section is shown in FIG. 8 of International application IB2019/052705(Kallman et al). An acrylic pressure sensitive adhesive solution, described as adhesive solution 1 in U.S. patent 5,296,277(Wilson et al) and containing 0.15 parts bisamide and 16 parts tackifier, was prepared at 38.5% solids.

The tackifier used was Terpene Phenol (Terpene Phenol) available as "SYLVARES" TP2019 from Keteng corporation of Houston, Tex (Kraton corporation, Houston, TX). Using a continuous coater/dryer line, a bath film of acrylic pressure sensitive adhesive solution was coated onto and dried on the structured side of the irregular channel embossed release liner. The exposed adhesive side of the adhesive coated random channel embossed release liner was laminated to film F1 at room temperature to form a random channel structured adhesive film. The film was then removed, removing all particles from the release liner, leaving a liner free of particles (liner P1).

Preparation of gasket example P2 (75% plane)

The pad P2 was created in a similar manner to pad P1, however, the targeted number of channels was increased such that the ratio of planar area to total surface area was designed to be 75%.

Preparation of gasket example P3 (65% plane)

The pad P3 was created in a similar manner to pad P1, however, the target number of channels was increased such that the ratio of the planar area to the total surface area was designed to be 65%.

Preparation of gasket example P4 (55% plane)

The pad P4 was created in a similar manner to pad P1, however, the target number of channels was increased such that the ratio of the planar area to the total surface area was designed to be 55%.

All parts, percentages, ratios, and the like in the examples and the remainder of the specification are by weight unless otherwise indicated. Solvents were obtained from Sigma Aldrich (Sigma-Aldrich) unless otherwise indicated.

Materials used in the examples

Reflective Polarizer (RP) optical films were prepared as described in international application IB 2019/050541.

Coating solution EX1

To a solution of 65 lbs of ethanol toluene cyclohexanone (42:28:31 w/w) was added 7 lbs of TEG-EH. 28 pounds of MOWITAL B20H PVB was slowly added to the solvent blend under high shear agitation and mixed until completely dissolved to form a 35% solids solution.

Coating solution EX2

To 80 pounds of Methyl Ethyl Ketone (MEK) solution was added 4 pounds of TEG-EH. 16 pounds of MOWITAL B60H PVB was slowly added to the solvent blend under high shear agitation and mixed until completely dissolved to form a 20% solids solution.

Coating solution EX3

To a 65 lb ethanol toluene cyclohexanone (42:28:31 w/w) solution was added 3.5 lb TEG-EH. 31.5 pounds of MOWITAL B20H PVB was slowly added to the solvent blend under high shear agitation and mixed until completely dissolved to form a 35% solids solution.

Coating solution EX4

This solution was prepared according to example 1 of U.S. patent publication 2006/0246296(Xia et al) except that the amount of polymer additive 1 was increased to equal 30 parts compared to PSA 1 (solids). To aid in coating processability, the binder was diluted with a blend of methyl ethyl ketone and methanol (77.5:22.5 wt/wt) to provide a 20.7% solids solution.

Coating solution EX5

This solution was prepared according to example 1 of U.S. patent publication 2006/0246296(Xia et al). To aid in coating processability, the binder was diluted with a blend of methyl ethyl ketone and methanol (77.5:22.5 wt/wt) to provide a 20.7% solids solution.

Coating solution EX6

To a solution of 65 pounds ethanol toluene cyclohexanone (42:28:31 weight/weight), 35 pounds MOWITAL B20H PVB was slowly added to the solvent blend under high shear stirring and mixed until completely dissolved to form a 35% solids solution.

Coating solution EX7

This solution was prepared according to example 1 of U.S. patent publication 2006/0246296(Xia et al) except that the amount of polymer additive 1 was increased to equal 36 parts compared to PSA 1 (solids). To aid in coating processability, the binder was diluted with a blend of methyl ethyl ketone and methanol (77.5:22.5 wt/wt) to provide a 20.7% solids solution.

Example 1

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 73 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 25 microns. The liner P1 was placed on top of the coated RP substrate so that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 2

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 73 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 25 microns. The liner P2 was placed on top of the coated RP substrate so that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 3

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 73 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 25 microns. The liner P3 was placed on top of the coated RP substrate so that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 4

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 73 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 25 microns. The liner P4 was placed on top of the coated RP substrate so that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 5

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 107 microns. The coated substrate was then dried at 150-200 ° f for 2 minutes to give a dry coating thickness of about 37.5 microns. The TREDEGAR 1035 dichroic front mask is placed on top of the coated RP substrate such that the structured or rough surface of the dichroic front mask is in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 6

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 107 microns. The coated substrate was then dried at 150-200 ° f for 2 minutes to give a dry coating thickness of about 37.5 microns. The SCOTCHCAL liner was placed on top of the coated RP substrate so that the structured or rough surface of the color-separated front mask was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 7

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 107 microns. The coated substrate was then dried at 150-200 ° f for 2 minutes to give a dry coating thickness of about 37.5 microns. An INFIANA liner was placed on top of the coated RP substrate so that the structured or rough surface of the color separation front mask was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 8

Coating solution EX2 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 125 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 25 microns. The liner P3 was placed on top of the coated RP substrate so that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 9

Coating solution EX3 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 89 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 31.25 microns. The liner P3 was placed on top of the coated RP substrate so that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 10

Coating solution EX4 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 151 microns. The coated substrate was then dried at 140-200 ° f for 2 minutes to give a dry coating thickness of about 31.25 microns. The SCOTCHCAL structured liner was placed on top of the coated RP substrate such that the structured surface of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 11

Coating solution EX4 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 60 microns. The coated substrate was then dried at 140-200 ° f for 2 minutes to give a dry coating thickness of about 12.5 microns. The liner P3 was placed on top of the coated RP substrate such that the structured surface of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 12

Coating solution EX2 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 125 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 25 microns. An INFIANA structured liner was placed on top of the coated RP substrate such that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 13

Coating solution EX5 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 151 microns. The coated substrate was then dried at 140-200 ° f for 2 minutes to give a dry coating thickness of about 31.25 microns. The SCOTCHCAL structured liner was placed on top of the coated RP substrate such that the structured surface of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 14

Coating solution EX5 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 60 microns. The coated substrate was then dried at 140-200 ° f for 2 minutes to give a dry coating thickness of about 12.5 microns. The liner P3 was placed on top of the coated RP substrate such that the structured surface of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 15

Coating solution EX6 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 89 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 31.25 microns. The liner P3 was placed on top of the coated RP substrate so that the structure of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (at 15 seconds/revolution) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Example 16

Coating solution EX7 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 151 microns. The coated substrate was then dried at 140-200 ° f for 2 minutes to give a dry coating thickness of about 31.25 microns. The SCOTCHCAL structured liner was placed on top of the coated RP substrate such that the structured surface of the liner was in direct contact with the coating. The combined film stack was passed through a hot roll laminator (15 sec/rev) containing a combination of heated steel/rubber nip rolls with the uncoated RP interface in contact with the steel nip roll and the unstructured side of the liner against the rubber nip roll. The nip roll temperature was set to 150 ° f. The gap between the nip idler rolls was set to 0.25mm and the pressure was set to 60psi-80 psi.

Comparative example C1

Coating solution EX1 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 73 microns. The coated substrate was then dried at 150-200 ° f for 3 minutes to give a dry coating thickness of about 25 microns.

Comparative example C2

Coating solution EX4 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 122 microns. The coated substrate was then dried at 140-200 ° f for 2 minutes to give a dry coating thickness of about 25 microns.

Comparative example C3

Coating solution EX5 was applied to the RP film via a slot-die coating process to give a wet thickness of approximately 122 microns. The coated substrate was then dried at 140-200 ° f for 2 minutes to give a dry coating thickness of about 25 microns.

Adhesive testing

The smooth movement test, the 2-finger pull test, and the repositionability test were performed on 6 inch flat single strength soda lime glass. The film samples had a minimum dimension of 7 inches by 7 inches to hang sufficiently on the glass.

Smooth shift test

The film sample was centered over the glass and positioned with the adhesive coated side in contact with the glass. One of the overhanging corners is then pulled in a horizontal motion (parallel to the plane of the glass) to pull the film away from the glass. The results were considered good if the film was pulled away without moving the glass. If the glass moves with the film, the result is considered poor.

2-finger drag test

The film sample was positioned with the adhesive coated side in contact with the glass. Two fingers were pressed down into the center of the sample with a gloved hand and the film sample was pulled towards the edge of the glass while maintaining downward pressure. If the glass moves with the film, the result is considered poor.

Relocatability test

The results were considered good if the film could be lifted vertically from the glass and moved to a new position without leaving any adhesive residue on the glass and without damaging the coating surface.

The results of the repositionability test are recorded in the following table.

Adhesive Tan delta measurement

Tan δ was determined for each sample via Dynamic Mechanical Analysis (DMA) using Q800 DMA with a fixed tension clamp or Discovery HR3 from TA Instruments. The results are plotted as a function of frequency in fig. 6.

Auditory transmission loss measurement

Glass laminates comprising inner and outer glass layers were prepared using various adhesive-coated reflective polarizers and a 0.38mm thick PVB layer between the reflective polarizer and the outer glass layer, and the acoustic transmission loss through the glass laminate was measured according to ASTM E90-09(2016) test standards, and the results are plotted as a function of frequency in fig. 7.

Terms such as "about" will be understood by those of ordinary skill in the art in the context of the use and description herein. If the use of "about" in the context of the use and description herein is unclear to those of ordinary skill in the art as applied to quantities expressing feature sizes, quantities, and physical characteristics, then "about" will be understood to mean within 10% of the specified value. An amount given as about a specified value may be exactly the specified value. For example, if it is not clear to a person of ordinary skill in the art in the context of the use and description in this specification, an amount having a value of about 1 means that the amount has a value between 0.9 and 1.1, and the value can be 1.

All cited references, patents, and patent applications cited above are hereby incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between the incorporated reference parts and the present application, the information in the preceding description shall prevail.

Unless otherwise indicated, descriptions with respect to elements in the figures should be understood to apply equally to corresponding elements in other figures. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure.

This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Accordingly, the disclosure is intended to be limited only by the claims and the equivalents thereof.