Extruded fluorescent film

Abstract

The present invention provides optical elements and compositions comprising an extruded polymer and a plurality of fluorophores or coloring pigments disposed within it. The fluorescent composition has a quantum yield of over 50% and maintains stable performance over long periods under exposure to oxygen, moisture, and light. In some embodiments, the extruded polymer is prepared as pellets, microparticles, nanoparticles, or films.

Description

[Technical Field]

[0001] This disclosure generally relates to colored pigments, fluorescent materials, and extruded films, and more particularly to co-extruded fluorescent materials and polymers that are robust against the permeation of oxygen, carbon dioxide, and / or moisture, and are stable under prolonged exposure to light, while limiting the number and complexity of film layers. [Background technology]

[0002] Luminescent films are particularly useful in applications requiring spectral sensitivity, such as agriculture and solar energy, and may be used to adjust incident light to improve crop growth or power conversion. They may also be used in other applications, including window coatings and displays. One significant challenge associated with luminescent films is that fluorophores tend to decompose under prolonged light exposure and in the presence of oxygen or moisture. While oxygen and moisture diffuse through all polymer materials, the selection and structure of materials can limit the diffusion of water, oxygen, carbon dioxide, or gas mixtures, minimizing at least part of the decomposition mechanism. By utilizing multilayer film structures, it becomes possible to individually optimize various film properties. Extrusion molding is a widely used technique in the manufacture of functional plastics, including agricultural films and food packaging materials. For example, inflation film extrusion is typically used to produce greenhouse covers and silage films with up to 11 layers. Various polymers are used in extruded multilayer films, including acrylic resins, polyethylene (PE), ethylene vinyl acetate (EVA), polyvinyl alcohol (PVOH), and ethylene vinyl alcohol (EVOH). Tie layers, such as maleic anhydride grafted polyethylene and maleic anhydride grafted ethylene vinyl acetate, are used in multilayer structures to bond layers that would not otherwise have good adhesion. Maleic anhydride has both hydrophobic and hydrophilic regions in its molecule, which allows for crosslinking between polar and nonpolar layers in multilayer structures.

[0003] Quantum dots (QDs) are exemplary fluorescent materials that have the potential to improve application performance by tuning their light spectra. A prime example is agriculture, where QDs are used to create lighting conditions that are most beneficial for plant growth; see, for example, International Publication No. 2018209000 (McDaniel et al.), “Luminescent Optical Elements for Agricultural Applications,” by the same applicant. [Overview of the Initiative]

[0004] In one embodiment, an optical element and composition are provided comprising an extruded polymer film and a plurality of fluorophores disposed therein. This fluorescent composition has a quantum yield of more than 50% and maintains stable performance over several years under oxygen, moisture, and light exposure. The extruded film comprises at least one layer having at least 1% by mass of an ethylene vinyl alcohol polymer copolymer and at least one tie layer. In some embodiments, the tie layer contains a fluorophore. In some embodiments, the extruded polymer is prepared as pellets, microparticles, nanoparticles, or a film. In some embodiments, at least one layer may be included that contains additives to stabilize the polymer against photodegradation. In other embodiments, at least one layer may be included that contains antioxidants or other sacrificial additives to delay oxygen penetration. In another aspect of the present invention, a composition is provided comprising an extruded copolymer of maleic anhydride-grafted polyethylene or maleic anhydride-grafted ethylene vinyl acetate and a plurality of coloring pigments disposed within the extruded polymer, wherein the pigments are present in greater than 0.5 mol%, and the composition maintains its optical properties within 20% of its initial level after one year of exposure to sunlight. The optical properties may be any one of the color index values, or optical density, or fluorescence quantum yield, or light transmittance.

[0005] In yet another aspect of the present invention, there is provided a greenhouse cover comprising an extruded polymer film having multiple layers and a plurality of fluorophores disposed in at least one layer of the extruded polymer film, wherein the fluorophores have a quantum yield of greater than 50% and the polymer film suppresses the gas emission of CO2 from the greenhouse to less than 10 cm 3 / m 2 / day. The fluorophore may be a quantum dot. Further, the polymer film of the greenhouse cover may further contain at least one layer having at least 1% by mass of an ethylene vinyl alcohol polymer copolymer; or at least one layer having maleic anhydride.

Brief Description of the Drawings

[0006] [Figure 1] It is a figure showing an outline of a multilayer film, where P is maleic anhydride graft LLDPE, maleic anhydride graft EVA, ethylene vinyl alcohol, thermoplastic polyurethane, or nylon. [Figure 2] It is a figure showing (a) a photograph of quantum dot (QD)-filled LLDPE obtained from Example 3, and (b) a photograph of a 7-layer inflation film obtained from Example 10. [Figure 3] Table 1 shows the optical properties of extruded QD single-layer films in various polymer matrices. [Figure 4] Table 2 shows the optical properties of multilayer extruded QD films in various polymer matrices.

Modes for Carrying Out the Invention

[0007] The polymer film is the simplest matrix for QDs. However, QDs may decompose when exposed to both light and oxygen for a long time, and films generally have a high surface area to volume ratio, which allows gas intrusion. There are few polymers that can limit gas diffusion by the polymer itself. In many cases, the polymer has a low oxygen transmission rate (OTR), for example, 10 cm 3 / m 2Achieving less than a day requires ceramic coating. However, this process is costly and generally impossible to combine with extrusion molding manufacturing technology. Furthermore, a low OTR typically corresponds to low permeability of other gases such as CO2. This could be beneficial for CO2-supplying greenhouses, as reduced gas leakage leads to less waste and more efficient use of CO2. Food-grade barrier films can limit oxygen diffusion to preserve food and potentially solve this problem, but they are not designed to be exposed to sunlight and other outdoor environmental conditions. Similarly, silage films often have a similar structure, but are usually designed only for single use and are not light-transmitting. Typically, food-grade and silage barrier films have multiple layers, each layer selected to have low water vapor transmission rate (WVTR) or oxygen transmission rate (OTR) properties (though usually not both). By stacking these layers, polymers with relatively low OTR and WVTR can be produced. Furthermore, these polymers are readily available, and since the manufacturing method involves extrusion molding, products containing these materials are usually affordable.

[0008] Definitions and Abbreviations The following explanations of terms and abbreviations are provided to better describe this disclosure and to guide those skilled in the art in the practice of this disclosure. As used herein, “comprising” means “including,” and the singular forms “a,” “an,” or “the” include multiple references unless the context explicitly states otherwise. The term “or” refers to a single element or a combination of two or more elements of the alternative elements described, unless the context explicitly states otherwise. Unless otherwise stated, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art relating to this disclosure. Methods and compositions suitable for carrying out or testing the compositions, systems, and methodologies described herein are described herein. However, it should be understood that other methods and materials similar or equivalent to those described herein may be used for carrying out or testing these compositions, systems, and methodologies. Therefore, the compositions, materials, methods, and examples disclosed herein are illustrative and not intended to be limiting. Other features of this disclosure will become apparent to those skilled in the art from the following detailed description and the appended claims.

[0009] Unless otherwise indicated, all numerical values ​​used herein or in the claims, such as amounts, percentages, temperatures, and times of constituents, should be understood to be modified by the term "about." Unless otherwise indicated, non-numerical properties such as colloidal, continuity, and crystalline properties used herein or in the claims should be understood to be modified by the term "substantially," meaning a considerable range or degree. Therefore, unless implicitly or explicitly indicated otherwise, the numerical parameters and / or non-numerical properties described are approximations that may depend on the desired properties, detection limits under standard test conditions or methods, limitations of processing methods, and / or the nature of the parameters or properties. Where embodiments are directly and explicitly distinguished from the prior art discussed, numerical values ​​in embodiments are not approximations unless the word "about" is used.

[0010] Photoluminescence (PL): The emission of light after absorption of light (electromagnetic radiation, photons). This is a form of luminescence (light emission) and is initiated by photoexcitation (excitation by photons). Toxicity: Indicates materials that may cause harm to living organisms due to the presence of phosphorus or heavy metals such as cadmium, lead, or mercury.

[0011] Quantum Dots (QD): Nanoscale particles that exhibit size-dependent electronic and optical properties due to quantum confinement. The quantum dots disclosed herein preferably have at least one dimension less than about 50 nanometers. The disclosed quantum dots can be colloidal quantum dots, i.e., quantum dots that can maintain a suspended state when dispersed in a liquid medium. Some of the quantum dots that can be utilized in the compositions, systems, and methodologies described herein are made from binary semiconductor materials having the formula MX, where M is a metal and X is typically selected from sulfur, selenium, tellurium, nitrogen, phosphorus, arsenic, antimony, or mixtures thereof. Exemplary binary quantum dots that can be utilized in the compositions, systems, and methodologies described herein include CdS, CdSe, CdTe, PbS, PbSe, PbTe, ZnS, ZnSe, ZnTe, InP, InAs, Cu2S, and In2S3. Other quantum dots that can be utilized in the compositions, systems, and methodologies described herein are ternary, quaternary, and / or alloyed quantum dots, including, but not limited to, ZnSe x S 1-x 、ZnTe x Se 1-x 、ZnTe x S 1-x 、CdSe x S 1-x 、CdTe x Se 1-x 、CdTe x S 1-x 、HgSe x S 1-x 、HgTe x Se 1-x 、HgTe x S 1-x 、ZnCdS, ZnCdSe, ZnCdTe, ZnHgS, ZnHgSe, ZnHgTe, CdHgS, CdHgSe, CdHgTe, ZnCdSe x S 2-x 、ZnCdSe x Te 2-x 、ZnHgSe x Te​​​​​​​​2-x , CdHgSeTe, CuAlS2, CuInS2, CuInSe2, CuInTe2, CuInGaSe2, CuInZnS2, CuZnSnSe2, CuInSe x S 2-x CuInZnSe x S 2-x , (Cu y Ag 1-y )InSe x S 2-x AgInS2, AgInSe2, and AgInSe x S 2-x Examples include quantum dots (where 0 ≤ x ≤ 2), but the use of non-toxic quantum dots is preferred. Embodiments of the quantum dots disclosed may consist of a single material or may include an inner core and an outer shell (e.g., a thin outer shell / layer formed by any suitable method such as cation exchange). The quantum dot may further include a plurality of ligands bound to the quantum dot surface.

[0012] Quantum yield (QY): The ratio of the number of photons emitted to the number of photons absorbed in a fluorescent fluorophore. Fluorescent phosphone: A material that absorbs a first light spectrum and emits a second light spectrum. Stokes shift: The energy difference between the location of the absorption shoulder or local absorption maximum and the maximum of the emission spectrum. Emission spectrum: A portion of the electromagnetic spectrum in which a photoluminescent material exhibits photoluminescence (in response to excitation by a light source), and whose magnitude is at least 1% of the PL emission peak.

[0013] Polymers: Large molecules, or macromolecules, composed of numerous repeating subunits. Such polymers range from well-known synthetic plastics such as polystyrene or poly(methyl methacrylate) (PMMA) to natural biomacromolecules such as DNA and proteins, which form the basis of biological structures and functions. Both natural and synthetic polymers are produced by the polymerization of many small molecules known as monomers. One useful class of polymers is maleic anhydride-grafted polymers, in which maleic anhydride can be grafted onto a suitable polymer backbone. The backbone to which maleic anhydride is grafted is often polyolefin (polyethylene, polypropylene, ethylene vinyl alcohol, etc.), but other types of polymers can also be used. Examples of polymers include maleic anhydride-grafted polyethylene, maleic anhydride-grafted ethylene vinyl acetate, poly(methyl methacrylate) (PMMA), maleic anhydride-grafted polyethylene vinyl alcohol, ethylene vinyl acetate (EVA), ethylene vinyl alcohol (EVOH), polyethylene vinyl alcohol (PVOH), polyamides such as nylon, polystyrene, polycarbonate, polyethylene terephthalate (PET), ionoplast, polyolefin (POE), silicone, and epoxy resins.

[0014] Self-absorption: The proportion of light emitted from multiple fluorophores that is absorbed by the same multiple fluorophores. CuInS2, CuInSe2, CuInGaSe2, CuAlS2, CuInZnS2, CuZnSnSe2, CuInSe x S 2-x CuInZnSe x S 2-x , and AgInSe x S 2-x (However, 0 ≤ x ≤ 2), and some quantum dots, including related compounds, are known to have exceptionally low self-absorption because the Stokes shift between the absorption spectrum and the emission spectrum is usually large, exceeding 100 meV (approximately 30 nm for peak emission at 600 nm). Description of a specific embodiment The object of this disclosure is to produce low-cost extruded fluorescent films that maintain their optical properties after prolonged exposure to light in the presence of oxygen and / or moisture. While it has already been demonstrated that "electronics-grade" barrier films can protect fluorophores, this method is expensive and lacks scalability. By utilizing an extruded polymer with barrier properties (preferably an ethylene vinyl alcohol polymer copolymer), various fluorophores (including, but not limited to, quantum dots) can be remarkably stabilized under light exposure in the presence of oxygen or moisture. Furthermore, by incorporating the fluorophores into tie-layer polymers, the manufacturing process can be significantly simplified, potentially reducing the number of layers required to achieve low OTR.

[0015] In various embodiments of the present invention, a multilayer film structure is used that includes one layer containing a QD that peaks at 600 nm to protect the fluorophore. The layers within the multilayer structure contain polymer materials having low oxygen permeability (OTR) and low water vapor permeability (WVTR). The fluorophore-containing layer generally contains 0.1 to 10% by mass of fluorophore. After more than two weeks under blue light at 50°C (accelerated aging conditions), the quantum yield (QY) of the film was confirmed to be maintained at least 90%, compared to 0% for polymers not designed for low OTR. In some embodiments, the QD has a vinyl alcohol or ethylene derivative chemically bonded to its surface to increase its solubility in the matrix and further limit the penetration of oxygen or water. The polymer can take on various form factors. For example, the polymer can be in the form of a film (which may be planar or nonplanar), or in the form of beads or pellets that can be used as a feedstock for manufacturing the film. As a specific example, the polymer can be molded into small particles of 10 nm to 1000 μm (microns) size. Ideally, the multilayer structure would be 5cm thick in a 1 mil film at 50% relative humidity and 20°C. 3 / m 2 It has an OTR value of less than / day. Furthermore, the multilayer structure has a film thickness of 1 mil with a density of 100 g / m² at a relative humidity of 90% and a temperature of 40°C. 2The WVTR value should be less than 1 / day. Furthermore, such a structure can provide protection against gas diffusion from both directions (up and down), which is important when the presence of gas could decompose the fluorophore.

[0016] In the compositions, apparatus, and methodologies described herein, a range of modifications, substitutions, combinations, and parameters can be adopted or utilized. For example, in some embodiments, the photoluminescence of a luminescent material may have maximum intensity at wavelengths in the range of 400 nm to 2000 nm, more preferably 550 nm to 1700 nm, and most preferably 550 nm to 750 nm. In some embodiments, the fluorophore may emit light spectra with a total width at maximum intensity greater than 1 nm, greater than 20 nm, greater than 30 nm, greater than 40 nm, greater than 100 nm, or greater than 200 nm. In other embodiments, the photoluminescence of a luminescent material may have maximum intensity at wavelengths greater than 550 nm.

[0017] In some embodiments, the photoluminescence of the luminescent material can be characterized by a quantum yield of at least 30%, at least 50%, at least 70%, or at least 80%. Various optical elements can be used in the optical paths of the apparatus and methodologies described herein. For example, in some embodiments, spectrally selective optical elements can be placed in the optical path between the object to be irradiated and the incident sunlight. Such optical elements include, for example, one or more elements selected from the group consisting of optical filters, quantum dot films, and colored glass. This type of spectrally selective optical element allows only a given portion of the spectrum to pass through.

[0018] In the systems and methodologies disclosed herein, quantum dots (QDs) and fluorophores of various compositions can be utilized. Some of these compositions are mentioned above. In some embodiments of the systems and methodologies described herein, QDs and fluorophores having compositions selected from the group consisting of CuInS2, CuInSe2, AgInS2, AgInSe2, ZnS, ZnSe, CuInZnSeS, CuGaS2, CuAlS2, and alloys of the aforementioned materials can be utilized. However, in many embodiments of the systems and methodologies disclosed herein, the composition CuInSe x S 2-x The use of QDs and fluorophores containing / ZnS is preferred. In some embodiments, two or more different types of quantum dots can be used in the systems, methodologies, and compositions described herein. These quantum dots may be compositionally different. For example, the luminescent material used herein may include a first type of quantum dot based on a first chemical property and a second type of quantum dot based on a second chemical property different from the first chemical property. Thus, for example, the first type of quantum dot may include, for example, CuInS2, while the second type of quantum dot may include AgInSe2 or CuAlS2. Similarly, the luminescent material described herein may include a first type of quantum dot based on a first set of dimensions (or dimensional distribution) of quantum dots and a second type of quantum dot based on a second set of dimensions (or dimensional distribution) of quantum dots different from the first set of dimensions (or dimensional distribution) of quantum dots. Therefore, for example, the first type of quantum dot may include a generally spherical quantum dot having a first diameter (e.g., 10 nm), and the second type of quantum dot may include a generally spherical quantum dot having a second diameter (e.g., 30 nm).

[0019] In a preferred embodiment, an optical element is provided comprising a polymer film containing at least one layer comprising an ethylene vinyl alcohol polymer copolymer and at least one layer comprising a maleic anhydride graft polymer. The ethylene vinyl alcohol polymer copolymer preferably contains at least 20% ethylene, more preferably 20-70%, and most preferably 20-50%. In several embodiments and applications, this amount of ethylene has been found to impart high moisture resistance and oxygen permeability to the resulting film or optical element without impairing other desirable properties of the film or optical element. In some embodiments, the optical element is provided with an extruded polymer film comprising at least one layer of aliphatic polyamide and further comprising multiple fluorophores having a quantum yield of more than about 75%.

[0020] In the embodiments of the optical elements and compositions disclosed herein, the polymers used to impart moisture resistance or oxygen resistance to these elements may have a variety of OTR and WVTR values, which may depend, for example, on the conditions the optical elements or compositions may encounter during use, the selection of the matrix material for the layer containing the fluorophore, and other such factors. Preferably, these polymers are used in a 1 mil thick film at 50% relative humidity and 20°C for 10 cm 3 / m 2 Less than 1 cm / day, more preferably, in a 1 mil thick film (approximately 25 μm) at a relative humidity of 50% and 20°C. 3 / m 2 Less than 0.1 cm in a 1 mil thick film at 50% relative humidity and 20°C. 3 / m 2 The OTR value is less than 1 / day. Preferably, these polymers are present in a 1 mil thick film at 90% relative humidity and 40°C at a density of 100 g / m². 2 Less than 1 day, more preferably 50 g / m² in a 1 mil thick film at 90% relative humidity and 40°C. 2Less than 1 day, and more preferably 30 g / m² in a 1 mil thick film at 90% relative humidity and 40°C. 2 Less than / day, most preferably 5 g / m² in a 1 mil thick film at 90% relative humidity and 40°C. 2 It has a WVTR value of less than / day.

[0021] The apparatus, structures, and methodologies disclosed herein are generally described in relation to applications exposed to sunlight and, in particular, to fluorescent materials. However, those skilled in the art will recognize that these apparatus, structures, and methodologies can also be used in a variety of other applications, such as indoor applications or with non-fluorescent materials such as conventional pigments. [Examples]

[0022] The following examples are non-limiting and are merely intended to further illustrate the compositions, systems, and methodologies described herein. (Example 1) Preparation of QD liquid concentrate (QDLC) contained in bis(ethylhexyl) sebacate. In a typical process, CuInS2 / ZnS quantum dots (Strem, catalog numbers: 29-8510, 29-8520, and 29-8530) were dissolved in bis(ethylhexyl) sebacate at a mass concentration of 70-95% to produce a liquid concentrate of QDs contained in bis(ethylhexyl) sebacate. This liquid concentrate was then supplied to an extrusion process and blended with maleic anhydride-grafted LDPE (PE-MAH) to obtain a quantum yield of over 75%. (Example 2) Preparation of octadecene-containing liquid concentrate (QDLC) In a typical process, CuInS2 / ZnS quantum dots (Strem, catalog numbers: 29-8510, 29-8520, and 29-8530) were dissolved in octadecene at a QD mass concentration of 70-95% to produce a liquid concentrate of QDs contained in octadecene. This liquid concentrate was then fed into an extrusion process and blended with maleic anhydride-grafted LDPE (PE-MAH) to obtain a quantum yield of over 75%.

[0023] (Example 3) Twin-screw extrusion of LLDPE including QD In a twin-screw extruder, linear low-density polyethylene (LLDPE) pellets were introduced from a hopper. Simultaneously, in a separate port, QD liquid concentrates from each of the individual samples from Examples 1 and 2 (with an LLDPE to QDLC ratio varying from 2% to 50%) were introduced into the extruder at 180°C. The resulting strands were cut to produce pellets of the blended material. The amount of quantum dots packed into the pellets varied from 1% to 47.5%. The pellets were subjected to extrusion molding of multilayer films using a single-screw extruder. The resulting films maintained photostability under sunlight exposure, and the QY was greater than 50% for at least 3 years.

[0024] (Example 4) Twin-screw extrusion of EVA including QD In a twin-screw extruder, ethylene vinyl acetate (EVA) pellets were introduced from a hopper, and simultaneously, in a separate port, QD liquid concentrates from each of the individual samples from Examples 1 and 2 (with an EVA to QDLC ratio varying from 2% to 50%) were introduced into the extruder at 150°C. The resulting strands were cut to produce pellets of the blended material. The amount of quantum dots packed into the pellets varied from 1% to 47.5%. The pellets were subjected to extrusion molding of multilayer films using a single-screw extruder. The resulting films maintained mechanical stability under sunlight exposure, and no embrittlement or other mechanical failure occurred for at least two years. (Example 5) Twin-screw extrusion of EVOH including QD In a twin-screw extruder, ethylene vinyl alcohol (EVOH) pellets were introduced from the hopper. Simultaneously, in a separate port, QD liquid concentrates from each of the individual samples from Examples 1 and 2 (with an EVOH to QDLC ratio varying from 2% to 50%) were introduced into the extruder at 220°C. The resulting strands were cut to produce pellets of the blended material. The amount of quantum dots packed into the pellets varied from 1% to 47.5%. The pellets were subjected to extrusion molding of multilayer films using a single-screw extruder.

[0025] (Example 6) Twin-screw extrusion of maleic anhydride grafted LDPE (PE-MAH) containing QDs In a twin-screw extruder, linear low-density polyethylene (PE-MAH) pellets were introduced from a hopper. Simultaneously, in a separate port, QD liquid concentrates from each of the individual samples from Examples 1 and 2 (with a PE-MAH to QDLC ratio varying from 2% to 50%) were introduced into the extruder at 180°C. The resulting strands were cut to produce pellets of the blended material. The quantum dot content in the pellets varied from 1% to 47.5%, achieving a quantum yield of over 75%. The pellets were subjected to extrusion molding of multilayer films using a single-screw extruder. The resulting films maintained photostability under sunlight exposure, with a QY of over 50% for at least 3 years. The resulting films maintained mechanical stability under sunlight exposure, with no embrittlement or other mechanical failure occurring for at least 2 years.

[0026] (Example 7) Twin-screw extrusion of maleic anhydride grafted EVA (EVA-MAH) containing QDs In a twin-screw extruder, maleic anhydride-grafted EVA (EVA-MAH) pellets were introduced from a hopper, and in a separate port, QD liquid concentrates from each of the individual samples from Examples 1 and 2 (with an EVA-MAH to QDLC ratio varying from 2% to 50%) were introduced into the extruder at 150°C. The resulting strands were cut to produce pellets of the blended material. The amount of quantum dots packed into the pellets varied from 1% to 47.5%. The pellets were subjected to extrusion molding of multilayer films using a single-screw extruder. The resulting films maintained photostability under sunlight exposure, with a QY of over 50% for at least 3 years. The resulting films maintained mechanical stability under sunlight exposure, with no embrittlement or other mechanical failure occurring for at least 2 years.

[0027] (Example 8) Twin-screw extrusion molding of thermoplastic polyurethane (TPU) containing QDs In a twin-screw extruder, thermoplastic polyurethane (TPU) pellets were introduced from the hopper. Simultaneously, in a separate port, QD liquid concentrates from each of the individual samples from Examples 1 and 2 (with an LLDPE to QDLC ratio varying from 2% to 50%) were introduced into the extruder at 165°C. The resulting strands were cut to produce pellets of the blended material. The amount of quantum dots packed into the pellets varied from 1% to 60%. The pellets were subjected to extrusion molding of multilayer films using a single-screw extruder. (Example 9) Twin-screw extrusion of nylon including QD In a twin-screw extruder, nylon (6434B grade, polyamide 6 / 6.6 / 12, UBE Chemical) pellets were introduced from the hopper. Simultaneously, in a separate port, QD liquid concentrates from each of the individual samples from Examples 1 and 2 (with a nylon-to-QDLC ratio varying from 2% to 40%) were introduced into the extruder at 205°C. The resulting strands were cut to produce pellets of the composite material. The amount of quantum dots packed into the pellets varied from 1% to 47.5%. Subsequently, the pellets were subjected to extrusion molding of multilayer films using a single-screw extruder.

[0028] (Example 10) Extrusion molding of multilayer QD inflation films In a multilayer inflation film apparatus containing up to nine single-screw extruders (A-I), plastic pellets containing the QD from Example 3 were mixed with maleic anhydride-grafted LLDPE pellets. The mixture was introduced into extruder E, LLDPE was loaded into extruders A, B, H, and I, LLDPE blended with maleic anhydride was loaded into extruders C and G, and ethylene vinyl alcohol pellets were loaded into extruders D and F. All of the above extruders were operated at temperatures fluctuating between 180°C and 220°C, and the resulting extruded materials were inflation-molded into multilayer films. The thickness of the multilayer films fluctuated between 100 μm and 250 μm, and the thickness of the QD layer fluctuated between 2 μm and 30 μm.

[0029] (Example 11) Extrusion molding of multilayer QD inflation films In a multilayer inflation film apparatus containing up to nine single-screw extruders (A-I), plastic pellets containing QD from Example 4 are mixed with maleic anhydride-grafted EVA pellets, the mixture is introduced into extruder E, LLDPE is loaded into extruders A, B, H, and I, LLDPE blended with maleic anhydride is loaded into extruders C and G, and ethylene vinyl alcohol pellets are loaded into extruders D and F. All of the above extruders are operated at temperatures fluctuating between 180°C and 220°C, and the resulting extruded material is inflation-molded into a multilayer film. The thickness of the multilayer film fluctuates between 100 μm and 250 μm, and the thickness of the QD layer fluctuates between 2 μm and 30 μm. (Example 12) Extrusion molding of multilayer QD inflation films In a multilayer inflation film apparatus containing up to nine single-screw extruders (A-I), plastic pellets containing the QD from Example 5 were introduced into extruder E, LLDPE was loaded into extruders A, B, H, and I, LLDPE blended with maleic anhydride was loaded into extruders C and G, and ethylene vinyl alcohol pellets were loaded into extruders D and F. All of the above extruders were operated at temperatures fluctuating between 180°C and 220°C, and the resulting extruded materials were inflation-molded into multilayer films. The thickness of the multilayer films fluctuated between 100 μm and 250 μm, and the thickness of the QD layer fluctuated between 2 μm and 30 μm.

[0030] (Example 13) Extrusion molding of multilayer QD inflation films In a multilayer inflation film apparatus containing up to nine single-screw extruders (A-I), plastic pellets containing the QD from Example 6 were introduced into extruder E, LLDPE was loaded into extruders A, B, H, and I, LLDPE blended with maleic anhydride was loaded into extruders C and G, and ethylene vinyl alcohol pellets were loaded into extruders D and F. All of the above extruders were operated at temperatures fluctuating between 180°C and 220°C, and the resulting extruded materials were inflation-molded into multilayer films. The thickness of the multilayer films fluctuated between 100 μm and 250 μm, and the thickness of the QD layer fluctuated between 2 μm and 30 μm.

[0031] (Example 14) Extrusion molding of 5-layer and 7-layer QD inflation films In the multilayer inflation film apparatus of Example 13, two specific embodiments are specifically considered: (1) a five-layer structure comprising polyethylene end layers (such end layers may be maleic anhydride grafted polyethylene) each containing a tie layer, two layers made of ethylene vinyl alcohol polymer (functioning as gas barriers) each adjacent to each end layer, and a maleic anhydride grafted polyethylene core further containing a desired fluorescent phosphopecton such as a desired quantum dot; and (2) a seven-layer structure comprising polyethylene end layers, two subsequent layers made of maleic anhydride grafted polyethylene each adjacent to each end layer, two subsequent layers made of ethylene vinyl alcohol polymer (functioning as gas barriers) each adjacent to each layer of maleic anhydride grafted polyethylene, and a maleic anhydride grafted polyethylene core further containing a desired fluorescent phosphopecton such as a desired quantum dot.

[0032] (Example 15) Greenhouse cover As an example of how these materials can be applied in practice, a highly optimized greenhouse cover comprising a multilayer extruded polymer film and a plurality of fluorophores disposed in at least one layer of the extruded polymer film, wherein the fluorophores have a quantum yield of more than 50%, and the polymer film reduces CO2 gas emissions from the greenhouse to 10 cm². 3 / m 2 There are greenhouse covers that suppress CO2 emissions to less than 1 / day. For example, the fluorophores of the greenhouse cover may be quantum dots or may contain quantum dots. This greenhouse cover combines the advantage of stabilizing fluorescence in plant photosynthesis by potentially using quantum dots with the CO2 barrier properties of at least one layer having at least 1% by mass of ethylene vinyl alcohol polymer copolymer, and can be used to maintain high levels of CO2 supplied to the greenhouse and increase plant growth. To simplify the manufacturing process and reduce costs, the greenhouse cover may contain at least one layer having maleic anhydride.

[0033] (Example 16) Sunlight-stabilized optical properties In many cases, colored pigments or other optical materials need to have stable properties under sunlight exposure. Novel compositions comprising maleic anhydride-grafted polyethylene or maleic anhydride-grafted ethylene vinyl acetate extruded copolymers can be used to protect multiple colored pigments. Ideally, the pigments are present in greater than 0.5 mol%, and the composition maintains a change in optical properties within 20% of a one-year period of sunlight exposure. Important optical properties are determined by the application and include, for example, color index values ​​(L*a*b* color coordinates, color values, CIELAB, or other color profiles), optical density (light absorption at a specific wavelength), fluorescence quantum yield (efficiency of light emission relative to absorption), or light transmittance (e.g., photosynthetically active radiation, PAR).

[0034] While the present invention is described with reference to certain details, such details are not intended to be considered as limiting the scope of the invention. A range of modifications, substitutions, combinations, and parameters can be adopted or utilized in the compositions and methodologies described herein. The above description of the present invention is illustrative and not intended to limit it. Therefore, it will be recognized that various additions, substitutions, and modifications can be made to the above embodiments without departing from the scope of the invention. Accordingly, the scope of the invention should be interpreted with reference to the appended claims.

[0035] Furthermore, the features described in the attached claims are particularly intended to be arranged in various combinations or partial combinations without departing from the scope of this disclosure. For example, features described in two or more claims are intended to be combined into a single claim without departing from the scope of this disclosure, regardless of whether the resulting combination of features is expressly disclosed in the attached claims or elsewhere in the disclosure.

[0036] (Example 16) Double-layer greenhouse cover As an example of how these materials can be applied in practice, a highly optimized greenhouse cover comprising two multilayer extruded polymer films and a plurality of fluorophores arranged in at least one layer of at least one of the extruded polymer films, wherein the fluorophores have a quantum yield of more than 50%, and both polymer films reduce CO2 gas emissions from the greenhouse to 10 cm². 3 / m 2 There are greenhouse covers that use CO2 gas to fill the space between two extruded films, keeping CO2 emissions below a certain limit per day. By using CO2 gas instead of air between the two extruded layer covers, the greenhouse heat can be well maintained due to the effect of the greenhouse gas. To prevent CO2 gas from leaking between the two films, both films require a layer that prevents CO2 gas release. This also serves to block heat from entering the greenhouse, making the environment inside the greenhouse easier to control and reducing the energy required to maintain the temperature inside the greenhouse.

Claims

1. An optical element comprising a multilayer extruded polymer film and a plurality of fluorophores disposed in at least one layer of the extruded polymer film, wherein the fluorophores have a quantum yield of more than 50%, and the polymer film comprises at least one layer having at least 1% by mass of an ethylene vinyl alcohol polymer copolymer and at least one layer containing at least 1% by mass of maleic anhydride.

2. The optical element according to claim 1, wherein the fluorescent phosphone emits a light spectrum having maximum intensity at wavelengths greater than 400 nm.

3. The optical element according to claim 1, wherein the fluorescent phosphopole is a quantum dot.

4. The aforementioned fluorescent phosphates are CuInS 2 CuInSe 2 AgInS 2 AgInSe 2 , ZnS, ZnSe, CuAlS 2 The optical element according to claim 1, which is a quantum dot comprising a material selected from the group consisting of the aforementioned materials and alloys of those materials.

5. The optical element according to claim 1, further comprising a polymer having oxygen or water barrier properties, wherein the fluorescent phosphopoide is dispersed in a polymer matrix, and the polymer matrix is ​​different from the polymer having oxygen or water barrier properties.

6. The optical element according to claim 1, wherein the polymer film comprises a layer of polymers selected from the group consisting of acrylate, polyethylene, polycarbonate, polyolefin, polyester, polyamide, polyvinyl butyral, ethylene vinyl acetate, ethylene vinyl alcohol, maleic anhydride graft polymer, combinations of these polymers or other similar polymers, and blends of these polymers or other similar polymers.

7. The optical element according to claim 1, wherein the polymer film contains at least one layer having an ethylene vinyl alcohol polymer copolymer containing ethylene in a mole fraction of at least 20%, ethylene in a mole fraction in the range of 20 to 70%, or ethylene in a mole fraction in the range of 20 to 50%.

8. The optical element according to claim 1, wherein the polymer film contains at least one outer layer containing a polymer selected from the group consisting of polyethylene, maleic anhydride grafted polyethylene, maleic anhydride grafted polyethylene vinyl alcohol, and maleic anhydride grafted poly(ethyl vinyl acetate).

9. The polymer film, in a 1 mil thickness film, is measured at a relative humidity of 50% and 20°C for 5 cm 3 / m 2 The optical element according to claim 1, having an OTR value of less than 1 / day.

10. The polymer film, with a thickness of 1 mil, has a density of 100 g / m² at a relative humidity of 90% and a temperature of 40°C. 2 The optical element according to claim 1, having a WVTR value of less than 1 / day.

11. The optical element according to claim 1, wherein the layer containing maleic anhydride has various grafting levels ranging from 0.2% to 0.2-0.5%, 0.5-1%, or more than 1%.

12. A greenhouse cover comprising an extruded polymer film having multiple layers and a plurality of fluorophores disposed in at least one layer of the extruded polymer film, wherein the fluorophores have a quantum yield of more than 50%, and the polymer film has a CO 2 gas emission from the greenhouse of less than 10 cm 3 / m 2 / day.

13. A composition comprising an extruded copolymer of maleic anhydride-grafted polyethylene or maleic anhydride-grafted ethylene vinyl acetate, and a plurality of fluorescent phores disposed within the extruded polymer, wherein the fluorescent phores are present in an amount of more than 0.5 mol%, and the composition has a quantum yield of more than 50%.

14. The composition according to claim 13, wherein the copolymer is composed of polymer pellets having a diameter between 0.1 mm and 1 cm.

15. The composition according to claim 13, wherein the copolymer is composed of polymer nanoparticles or microparticles having a diameter in the range of 10 nm to 1000 μm.

16. The composition according to claim 13, wherein the fluorescent phosphopoide is chemically bonded to at least one polymer group selected from the group consisting of maleic anhydride grafted polyethylene, maleic anhydride grafted ethylene vinyl alcohol, and maleic anhydride grafted ethylene vinyl acetate.

17. The aforementioned fluorescent phosphates are CuInS 2 CuInSe 2 AgInS 2 AgInSe 2 , ZnS, ZnSe, CuAlS 2 The composition according to claim 13, wherein the quantum dot comprises a material selected from the group consisting of the aforementioned materials and alloys of those materials.

18. The composition according to claim 13, further comprising a polymer having oxygen or water barrier properties that protects the fluorescent phosphone from long-term degradation.

19. The composition according to claim 13, wherein the copolymer contains an additive for stabilizing the polymer against degradation.

20. The composition according to claim 13, wherein the copolymer contains an antioxidant or other sacrificial additive for delaying the entry of oxygen.

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