73 results about "Polyethylene naphthalate" patented technology

The invention relates to an internal serial metallized film, a preparation method, a filter capacitor and a base film, the base film is made of a blending material of polyethylene glycol terephthalate and polyethylene naphthalate according to a mass ratio of 2: 3, and the thickness of the base film is 8-12 [mu] m; the multi-layer metallization layer is arranged on the base film and comprises a first metal layer, a buffer layer and a second metal layer, the buffer layer is located between the first metal layer and the second metal layer, the patterned structure forms a plurality of conductive units which are connected in series on the multi-layer metallization layer, each conductive unit is in a regular hexagon shape, and the first metal layer is arranged on the first metal layer. The side length of the conductive units is 3-6mm, and an isolation belt with the width of 0.3-0.8 mm is arranged between the adjacent conductive units. According to the invention, a plurality of key performance indexes such as high-frequency filtering performance, voltage endurance capability, oxidation resistance, structural stability, light transmission and the like are optimized and improved.

To provide a biaxially stretched film that has excellent folding resistance and heat resistance.SOLUTION: A biaxially stretched film contains a polyethylene naphthalate copolymer (A), wherein the average of hysteresis loss ratios after a tensile cycle test up to 5% tensile strain in the MD direction and in the TD direction is 47.0% or less.SELECTED DRAWING: None

The invention relates to the technical field of electrochemistry, in particular to a polymer composite film, a composite current collector and a preparation method thereof, a positive electrode and application thereof. The polymer composite film comprises a polymer base layer, and a first modified layer and a second modified layer which are respectively arranged on two opposite side surfaces of the polymer base layer, the material of the polymer base layer comprises one or more of polyethylene glycol terephthalate, poly (1, 4-cyclohexylenedimethylene terephthalate) and polyethylene glycol terephthalate-1, 4-cyclohexylenedimethylene terephthalate; the first modified layer and the second modified layer respectively and independently comprise the following components: a functional polymer material; the functional polymer material comprises one or more of polyethylene naphthalate, polyadipyl metaphenylene diamine, a liquid crystal polymer, polyformaldehyde, polyphenylene sulfide and polyphenyl ether. The polymer composite membrane disclosed by the invention can be effectively broken when being damaged by relatively strong external force, so that thermal runaway of the battery can be effectively prevented.

The present application provides a liquid cooling module, a liquid cooling module and an electronic device, wherein the liquid cooling module comprises a pump and a liquid cooling module. The pump base is integrally sealed and connected to the liquid cooling module. The liquid cooling module comprises a flexible membrane and a rigid base. The elongation at break of the pump base and the liquid cooling module material is greater than 10%, including materials such as polyethylene terephthalate copolymer, polyethylene naphthalate, polyethylene 2,5-furandicarboxylate, polyimide, polyetheretherketone, biaxially stretched polypropylene, etc.; the monomers of the polyethylene terephthalate copolymer include terephthalic acid, ethylene glycol and a hard segment molecular structure. The liquid cooling module of the present application is formed by stacking the pump and the liquid cooling module, selecting materials and integrated welding, and does not require pre-tightening force to achieve integrated sealing of the flexible system, without assembly leakage, and can dynamically adapt to bending use, changes in system pressure and volume, and higher tolerance temperature, and is suitable for mobile electronic devices such as straight-screen phones, folding mobile phones, folding PCs, wearables, accessories, etc.

The invention discloses a protective base film for optical cement, comprising: a core layer sandwiched between a first surface layer and a second surface layer; the core layer comprises first polyester; each of the first surface layer and the second surface layer comprises first polyester and functional master batches in a mass ratio of (45-50): (50-55), and the functional master batches comprise polyethylene naphthalate, second polyester and modified barium sulfate. The dispersity is improved by mixing the functional master batch and the first polyester, so that the haze and the light transmittance of the base film are optimized; through the functional master batch prepared from the polyethylene naphthalate, the heat resistance and the stability of the base film are optimized, the transmittance of the base film is improved, and the haze is reduced.

The invention provides a protective film for a wavelength conversion sheet, a wavelength conversion sheet, and a backlight unit. The protective film for a wavelength conversion sheet has a structure in which a first barrier layer-side surface of a first film comprising a first substrate and a first barrier layer and one surface of a second film comprising a second substrate are bonded with an adhesive layer interposed therebetween, the first substrate being made of a polyethylene terephthalate film or a polyethylene naphthalate film, and the first barrier layer being made of a polyethylene terephthalate film or a polyethylene naphthalate film. The first substrate is made of a polyethylene terephthalate film or a polyethylene naphthalate film, the second substrate is made of a polyethylene terephthalate film or a polyethylene naphthalate film, the thickness of the first substrate is larger than that of the second substrate, and a coating layer is arranged on one surface of the protective film for the wavelength conversion sheet. The protective film for a wavelength conversion sheet has a coefficient of thermal expansion in the TD direction in a temperature range of 30-90 DEG C of-0.8 * 10-4 / K or more and 0.5 * 10-4 / K or less.

The present invention provides a PET / PBT composite material and a preparation method thereof, and relates to the field of polymer composite materials, the PET / PBT composite material comprises the following raw materials by weight: 30-50 parts of PBT resin; 20 to 40 parts of PET resin; 10 to 20 parts of polyethylene naphthalate; 5 to 15 parts of modified nano aromatic amide fiber; 8 to 15 parts of ethylene-methacrylic acid copolymer neutralized by metal ions; 3-8 parts of a compatilizer; 0.3 to 1 part of an antioxidant; and 0.5 to 1.5 parts of a lubricant. The modified nano aromatic amide fiber provides rigidity, the ionic polymer provides toughness, the modified nano aromatic amide fiber and the ionic polymer are combined, the fiber serves as a rigid framework to bear main loads, and the ionic polymer distributed on the interface of the fiber and a matrix efficiently dissipates impact energy and prevents crack propagation through reversible fracture of dynamic bonds of the ionic polymer. Meanwhile, high strength, high modulus, ultrahigh toughness and high heat resistance are realized.

The invention discloses an anti-static polyester film and a preparation method thereof, and mainly relates to the technical field of layered products composed of polyester. Compared with the prior art, the antistatic polyester film provided by the invention is prepared from A and B master batch materials through the steps of melting, sheet casting, stretching and the like, the A-layer master batch material is polyethylene glycol terephthalate and polyethylene naphthalate, and the B-layer master batch material is a polyethylene glycol terephthalate, antistatic agent and carbon nanotube composite material. According to the carbon nanotube composite material, the dispersity of the carbon nanotubes in polyester and the interface bonding force of the carbon nanotubes and a matrix are modified and enhanced, and a continuous conductive network is constructed to improve the antistatic performance; meanwhile, the interaction in the composite material is enhanced, so that the tensile strength of the film is improved.

An optically anisotropic polymer thin film includes a crystallizable polymer and an additive configured to interact with the polymer (e.g., via π-π interactions) to facilitate chain alignment and, in some examples, create a higher crystalline content within the polymer thin film. The polymer thin film may be characterized by a bimodal molecular weight distribution where the molecular weight of the additive may be less than approximately 50% of the molecular weight of the crystallizable polymer. Example crystallizable polymers include polyethylene naphthalate, polyethylene terephthalate, polybutylene naphthalate, polybutylene terephthalate, as well as derivatives thereof. Example additives, which may occupy up to approximately 10 wt. % of the polymer thin film, include aromatic ester oligomers, aromatic amide oligomers, and polycyclic aromatic hydrocarbons, for example. The optically anisotropic polymer thin film may be characterized by a refractive index greater than approximately 1.7 and an in-plane birefringence greater than approximately 0.2.

The present application relates to a kind of high barrier bottle grade polyester and its preparation method, belong to polyester technical field.The high barrier bottle grade polyester includes polyethylene terephthalate, polyethylene naphthalate, composite nano barrier agent, reactive compatibilizer.The composite nano barrier agent is composed of modified nano silicon dioxide and modified halloysite nanotube.The reactive compatibilizer is styrene-glycidyl methacrylate copolymer.The present application realizes the bottle grade polyester of high barrier, high transparency and low acetaldehyde under low PEN addition amount by the synergistic effect of the triple mechanism of intrinsic barrier of PEN, physical maze effect of composite nano barrier agent and interface strengthening of reactive compatibilizer, and the technology of master batch pre-dispersion process, vacuum exhaust and acetaldehyde absorption is combined, meets the requirement of food packaging, and is suitable for juice, tea beverage, edible oil and other packaging containers.

The present application relates to the technical field of polyester material modification, and particularly relates to a high-transparency polyethylene naphthalate material, a preparation method and application, aiming at the problems of fast crystallization rate of the PEN material in the process of processing and molding, easy crystallization of thick products, light transmittance reduction caused by the crystallization, and insufficient material toughness, the present application introduces a diol monomer containing a side group and a flexible chain segment diol monomer into the PEN melt polycondensation process for copolymerization, wherein the diol containing a side group introduces a steric hindrance structure in the molecular chain to destroy the regular packing of the PEN molecular chain, thereby inhibiting the material crystallization behavior and improving the light transmittance of the thick product; the flexible diol introduces a flexible chain segment in the molecular chain to increase the free volume of the molecular chain and improve the molecular chain movement ability, thereby improving the material toughness. Through the above-mentioned synergistic copolymerization modification method, the crystallization tendency of the PEN material can be effectively reduced, the obtained PEN thick product has excellent light transmittance and toughness at the same time, and is suitable for the preparation of high-performance transparent polyester products.

The application discloses a kind of optical adhesive protective group film, comprising: core layer, it is arranged between first surface layer and second surface layer;Core layer includes first polyester;First surface layer and second surface layer include the mass ratio of (45~50) and functional master batch of (50~55) first polyester, and functional master batch includes polyethylene naphthalate, second polyester and modified barium sulfate.By mixing the dispersibility of functional master batch and first polyester is improved, and then the haze and light transmittance of base film are optimized;By polyethylene naphthalate preparation functional master batch, the heat resistance and stability of base film are optimized, and its transmittance is improved and haze is reduced.

The present invention discloses a polyethylene naphthalate composite material with high impact strength and a preparation method thereof, belonging to the field of composite materials. The preparation method includes: by mass parts, mixing 100 parts of polyethylene naphthalate, 10 - 40 parts of polyacrylate elastomer, 0.5 - 1.5 parts of heat stabilizer, and 0.5 - 1 part of antioxidant assistant uniformly, and melt-extruding to obtain the polyethylene naphthalate composite material with high impact strength. In the present invention, the polyacrylate elastomer with low crosslinking density is dispersed into the PEN resin to form a phase morphology with the characteristic of low matrix ligament thickness. This morphology can effectively increase the ductility of PEN, enabling it to exhibit better energy absorption and deformation ability under impact, thereby avoiding brittle fracture. The polyethylene naphthalate composite material provided by the present invention has excellent comprehensive performance, a simple preparation process, and easily available raw materials, and has broad prospects for industrial application.

A foamed polymer composition includes a matrix polymer component, and from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof. The matrix polymer component includes polybutylene terephthalate (PBT), polyetherimide (PEI), polyethylene terephthalate (PET), polycarbonate (PC), poly(p-phenylene oxide) (PPO), polystyrene (PS), polyphenylene sulfide (PPS), polypropylene (PP), polyamide (PA), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), copolymers thereof, or a combination thereof. Methods for forming foamed polymer compositions, including core-back molding methods and extrusion foaming methods, are also described.

The invention discloses an anti-blue-light and anti-ultraviolet polyester film as well as a preparation method and application thereof, and mainly relates to the technical field of layered products consisting of polyester. Compared with the prior art, the anti-blue light and anti-ultraviolet polyester film is obtained by melting, casting and stretching three layers of master batch materials A, B and C, the layer A master batch material is polyethylene glycol terephthalate, synergistic resin and an anti-blocking agent, the layer B master batch material is polyethylene glycol terephthalate, an ultraviolet light absorber and a blue light absorber, and the layer C master batch material is polyethylene glycol terephthalate, a synergistic resin and an anti-blocking agent. And the master batch material of the layer C is polyethylene glycol terephthalate, synergistic resin and polyethylene naphthalate. Compared with the prior art, the method has the advantages that the compactness and uniformity of the internal structure of the film are improved, the dispersity and stability of the functional additive are improved, the defects are reduced, the synergistic improvement of blue light resistance and ultraviolet resistance is finally realized, and meanwhile, the mechanical property of the film is guaranteed.

A multilayer optical film includes a plurality of alternating polymeric first and second layers numbering 10 to 120 in total. Each of the first and second layers having an average thickness of less than about 500 nm. The first layers include polyethylene naphthalate, and the second layers include a copolyester comprising at least one of cyclohexane dicarboxylic acid groups, adipic acid groups, or tetramethyl cyclobutanediol groups, such that for substantially normally incident light and for at least one polarization state, the multilayer optical film has an average optical reflectance of at least about 70% in a wavelength range at least about 200 nm wide.

The invention relates to a modified polycarbonate master batch, a composite polycarbonate material as well as a preparation method and application thereof. The modified polycarbonate master batch is prepared from the following raw materials in parts by weight: 70 to 95 parts of polycarbonate, 5 to 25 parts of polyethylene naphthalate, 0.1 to 2 parts of epoxy resin coupling agent and 0.5 to 3 parts of compatilizer A. The composite polycarbonate material is prepared from the following components in parts by weight: 50 to 90 parts of modified polycarbonate master batch, 5 to 35 parts of polyetherimide and 0.2 to 2 parts of compatilizer B. Polyethylene naphthalate is used for modifying polycarbonate, the high-temperature-resistant modified polycarbonate master batch is prepared, then the modified polycarbonate master batch and polyetherimide are blended, and the prepared composite polycarbonate material has excellent high-temperature resistance and mechanical performance.

The application discloses high-characteristic-viscosity polyethylene naphthalate with a branched structure and a preparation method thereof, and belongs to the technical field of material chemical industry. The preparation method comprises the following steps: 60-65 parts of dimethyl 2,6-naphthalene dicarboxylate, 35-40 parts of ethylene glycol, 0.1-2 parts of three / four branched monomers, 0.01-0.5 parts of a catalyst and 0.01-0.5 parts of an antioxidant are mixed according to the mass fraction, a polymerization reaction is carried out, methanol is removed, and then ethylene glycol is removed. In the application, the three / four branched monomers are added in a certain amount to form a branched chain structure on the polymer main chain, so that the melt viscosity of the polymer is reduced, which is beneficial to the mass transfer and diffusion of the small-molecule byproduct ethylene glycol, and then is beneficial to the forward progress of the polycondensation reaction, and the reaction time is shortened. The branched structure reduces the viscosity, more byproduct ethylene glycol can be removed, the reaction degree is increased, and the product obtained has a higher characteristic viscosity.

The invention provides a polyethylene naphthalate film and a preparation method thereof.The preparation method includes the three steps of pre-crystallization treatment, rapid hot stretching and annealing treatment.The preparation method includes the steps that a PEN casting piece is heated to the temperature range higher than the glass-transition temperature and kept for 15-60 minutes, small-size microcrystals are formed in the PEN casting piece, and the PEN casting piece is formed; the microcrystals can be used as nucleation points for stretching induced crystallization, so that the crystallization rate and uniformity in the subsequent stretching process are improved; then, the crystallized PEN casting piece is rapidly stretched at the temperature of 140-170 DEG C, and the deformation rate is 0.1-1 s <-1 >; the PEN molecular chain is highly oriented along the stretching direction, and meanwhile, the formation of oriented crystals is promoted, so that the modulus and the strength of the film are improved; and finally, carrying out annealing treatment on the PEN film obtained after rapid hot stretching in a range of 150-180 DEG C. The steps are favorable for further perfecting an oriented crystal structure, improving the crystallinity and effectively releasing internal stress, so that the dimensional stability and the heat resistance of the film are improved.

The present invention discloses an insulating packaging film for a lithium battery, a preparation process, and a fast-charging lithium battery. The insulating packaging film is used between multiple stacked battery cells within the fast-charging lithium battery to provide insulation and bonding. The film comprises a heat-sealing layer, an adhesive layer, an insulating layer, an adhesive layer, and a heat-sealing layer, which are sequentially laminated from the inside out. The insulating layer is made of one of polyimide, polyethylene terephthalate, and polyethylene naphthalate, with a thickness of 5-30 μm. The heat-sealing layer is made of polypropylene or a combination of polypropylene and polyethylene, with a thickness of 10-40 μm. The adhesive layer is made of a modified polyolefin resin. The insulating packaging film of the present invention has a simple structure, is easy to manufacture, and is much thinner than aluminum film, significantly reducing the space occupied by the battery and increasing the battery's unit volume energy density by 4.75-10%, thereby improving the fast-charging speed of the lithium battery. The heat-sealing layer increases fluidity by adding polyethylene to the polypropylene, thereby improving the packaging efficiency of the battery cells.

The invention relates to the technical field of polymer preparation, in particular to a polyethylene naphthalate polymer and a preparation method and application thereof.The preparation method comprises the steps that nanocellulose is subjected to acid hydrolysis treatment and then subjected to ball milling, and then modified nanocellulose is obtained through silane coupling agent modification treatment; 2, 6-dimethyl naphthalate, ethylene glycol, a bio-based catalyst and the modified nano cellulose are added into a polymerization kettle, after uniform dispersion in a system, heating is performed for transesterification, then a heat stabilizer is added, temperature and pressure are controlled for pre-polycondensation, and the modified nano cellulose is obtained. And finally, regulating and controlling the temperature and the pressure, and carrying out final polycondensation to obtain the polyethylene naphthalate polymer stock solution. The bio-based catalyst comprises citric acid and gallic acid. The polymer is free of heavy metal pollution, low in cost, excellent in strength performance, high in thermal deformation temperature and good in light transmittance. The polyethylene naphthalate polymer is suitable for the fields of flexible electronic packaging, new energy battery diaphragms and the like.

The invention discloses a fluorine-free high-weather-resistant polyethylene naphthalate film and a preparation method thereof. PEN resin is hot-pressed and then quenched to obtain a PEN film; by weight, 0.05-5 parts of nano-silicon dioxide particles, 5-10 parts of methyl methacrylate, 1-10 parts of butyl acrylate, 1-10 parts of acrylic acid, 1-20 parts of 5-(4-(2-hydroxybenzoyl)phenyl)pentyl acrylate, 1-5 parts of KH-570, 0.01-0.1 parts of an oil-soluble free radical initiator and 60-90 parts of a solvent are added to obtain a weather-resistant coating; the PEN base film is immersed in the weather-resistant coating and baked to obtain a fluorine-free high-weather-resistant PEN film. The high-weather-resistant PEN film has excellent resistance to ultraviolet degradation, can meet the use requirements in harsh environments such as strong outdoor ultraviolet rays, high heat and high humidity, and has the advantages of being fluorine-free, having good insulation and excellent barrier properties.

The invention relates to the technical field of photoelectric materials and devices, in particular to a flexible perovskite photovoltaic module barrier film and a preparation method thereof. The flexible perovskite photovoltaic module barrier film comprises a substrate layer, a first barrier layer, a self-repairing layer and a second barrier layer, the substrate layer is any one of a polyethylene glycol terephthalate film and a polyethylene naphthalate film, and the thickness of the substrate layer is 100-150 microns; the first barrier layer comprises any one of a SiO2 thin film and an Al2O3 thin film, and the thickness of the first barrier layer is 20-50 nm; the self-repairing layer is prepared from hydroxyethyl methylacrylate, dodecafluoroheptyl methacrylate, a cross-linking agent and a photoinitiator, the cross-linking agent comprises any one of a disulfide bond-containing cross-linking agent and a dihydrazide cross-linking agent, and the thickness of the cross-linking agent is 2-5 microns. And the second barrier layer comprises any one of an Al2O3 film, a fluorosilicone resin film, a thermoplastic polyolefin film and an organic-inorganic hybrid layer. And the stability and the damp-heat cycle resistance of the flexible perovskite photovoltaic module can be improved.

The invention discloses a liquid crystal alignment film structure of a foldable electronic reader, which relates to the technical field of liquid crystal alignment films and comprises a surface treatment layer, a protective layer, a photosensitive layer, an alignment layer, an adhesion layer and a substrate layer which are sequentially distributed from top to bottom, the substrate layer is prepared from a mixture of polyethylene glycol terephthalate and polyethylene naphthalate, the orientation layer is prepared from polyimide, and the adhesion layer, the photosensitive layer, the protection layer and the surface treatment layer are used as auxiliary materials to jointly form the liquid crystal orientation film structure, so that the preparation is simple and easy to operate; and the prepared liquid crystal alignment film has good thermal stability, tensile property and optical property, is higher in mechanical strength, can keep stable performance in a high-temperature environment, can provide a clearer display effect, is expanded in application range, and is convenient for wide popularization and application.

Described herein are negative electrodes comprising polymer base layers and current collector layers, formed from alloys or multi-layered structures, lithium electrochemical cells (e.g., lithium metal and lithium-ion cells), comprising such electrodes, and methods of fabricating such electrodes. In some examples, a negative electrode comprises a polymer base layer, a current collector layer, and a negative active material layer. The polymer base layer can be formed from one or more of polyethylene terephthalate, polyethylene naphthalate, polypropylene, polycarbonate, polyethylene, polyimide, cellulose, and nylon. The negative current collector layer can be formed from an alloy or a multi-layered structure comprising at least two or more elements selected from the group aluminum, cadmium, chromium, cobalt, copper, indium, lithium, manganese, magnesium, molybdenum, nickel, phosphorous, silicon, silver, sodium, tin, titanium, vanadium, and zinc. For example, the negative current collector layer can be formed from an alloy of titanium and aluminum or a lithium alloy.

To provide a blow molding composed of a resin composition, having excellent transparency and heat resistance, with suppressed necking phenomenon in a drawing process.SOLUTION: A blow molding comprises a blow-molded resin composition. Relative to 100 pts.wt. of (A) polyethylenenaphthalate resin (A component), the resin composition comprises (B) polyether imide resin (B component) 60-150 pts.wt.SELECTED DRAWING: None

The present invention provides a photocurable resin composition that can be cured with visible light, can be used as an adhesive or a sealant for members that include polyethylene naphthalate (PEN) and do not readily transmit ultraviolet light, and also has excellent acidic aqueous solution resistance. This photocurable resin composition includes (A) an oligomer that has at least one (meth)acryloyl group, (B) a thioxanthone photoinitiator, and (C) a tertiary amine that has at least two aromatic rings in the molecule thereof.

The present invention discloses a polyethylene naphthalate film with high light transmittance and a preparation method thereof. The surface of the PEN film is subjected to plasma treatment; dimethyldiethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane and a solvent are mixed, and hydrolysis and condensation are carried out under the action of a catalyst to obtain a phenylvinyl silicone resin sol; a high-boiling solvent is used to displace ethanol in the phenylvinyl silicone resin sol, and filtration is carried out to obtain a high-transparency silicone resin solution; the high-transparency silicone resin solution is coated on the surface of the plasma-treated PEN film, and baking is carried out. The PEN film has excellent light-transmitting performance, and also has excellent heat resistance and dimensional stability, and can be used as an ITO base film, a support film for a liquid crystal display polarizer, and other fields. The method is simple, easy to operate, and the raw materials used are non-toxic and easily available, and a PEN optical-grade film with high cost performance can be prepared.

The application discloses a titanium-magnesium bimetallic catalyst for synthesizing polyethylene naphthalate resin and a preparation method and application thereof, and the preparation method comprises the following steps: carrying out static reaction on a titanium salt, a magnesium salt, a hydrolysis promoter and water at 100-300 DEG C for 12-48 h to obtain a bimetallic gel; adding ethylene glycol into the bimetallic gel and reacting at 80-180 DEG C for 3-6 h, filtering and drying to obtain a titanium-magnesium bimetallic catalyst for polymerization. The titanium-magnesium bimetallic catalyst in the application forms a multiradical ring intermediate through an ester bond and a hydroxyl group, changes an electron cloud arrangement mode, effectively inhibits the occurrence of an etherification side reaction, reduces the generation of a diethylene glycol segment, and avoids the yellowing problem of a PEN resin. The catalyst has the advantages of simple synthesis, remarkable catalytic effect, low colority of a PEN product and the like, and has a wide industrial application prospect.

The present invention relates to storage of alcoholic beverages, and in particular provides a system for storing an alcoholic beverage, which system comprises (i) a rigid and airtight outer container, and (ii) a wooden barrel for containing an alcoholic beverage, and which wooden barrel is contained within the outer container, characterised in that said outer container is formed from polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).