UV-curable protective film

Abstract

In some embodiments, the curable composition comprises: at least one high Tg alkyl (meth) acrylate, the high Tg alkyl (meth) acrylate being free of polar 5 groups and having a homopolymer Tg of at least 60 DEG C; at least one low Tg alkyl (meth) acrylate free of polar groups and having a homopolymer Tg of less than-30 DEG C; at least one crosslinking agent; and at least one photoinitiator. The curable composition is solvent-free and inkjet printable, has a viscosity of less than 25 centipoise at room temperature, and when cured to form a 100 [mu] m thick coating, has a Tg of at least 50 DEG C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 g / inch (7.7 N / m) as measured by 180 DEG peel adhesion, a Young's modulus of greater than 0.5 GPa, and is optically transparent.

Description

Summary of the Invention

[0001] This document discloses curable compositions, articles prepared from these curable compositions, and methods for forming the articles. The curable compositions can be ink compositions, as they are inkjet printable.

[0002] In some embodiments, the curable composition comprises: at least one high-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of at least 60°C; at least one low-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of less than -30°C; at least one crosslinking agent; and at least one photoinitiator. The curable composition is solvent-free and inkjet printable, has a viscosity of less than 25 centipoise at room temperature, and when cured to form a 100-micron thick coating, has a Tg of at least 50°C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 g / inch (7.7 N / m) as measured by 180° peel adhesion, a Young's modulus greater than 0.5 gigapascals, and is optically transparent.

[0003] Articles of manufacture are also disclosed. In some embodiments, the article of manufacture includes a substrate such as glass and a curable coating disposed on at least a portion of the surface of the substrate. The curable coating comprises the aforementioned curable coating composition that has been applied and cured. A method for preparing the article of manufacture is also disclosed. Detailed Implementation

[0004] Many optical and electronic devices have surfaces that require protective layers. These protective layers typically have stringent optical requirements, such as optical transparency. The protective layers provide protection against scratches and cracks, and also prevent contamination from adversely affecting the surface. Currently, protective products with a PSA (pressure-sensitive adhesive) coating, such as PET (polyethylene terephthalate) films, are used. These products are laminated onto surfaces to protect them.

[0005] In new articles requiring protective films, there are articles with unusual sizes or shapes, thus the attachment of the protective film articles can be problematic. Preparing film articles with suitable shapes and sizes requires cutting the film to fit the desired surface to be protected. The film can be cut before or after lamination. Cutting to fit the surface can be difficult, time-consuming, and expensive. Furthermore, since film articles consist of an adhesive layer and a film layer, the article is laminated to the surface of the article. While lamination is a very useful process, it can be problematic for articles with large surface areas and for articles with unusual shapes (where optical transparency is required). For the lamination of larger film articles, lamination defects such as bubbles, wrinkles, and tears are more likely to occur. Therefore, a method is needed to prepare protective films without pre- or post-processing the film to fit the surface. Additionally, there is a need to adhere the protective film to the surface without using a lamination process.

[0006] A suitable alternative to laminating film / PSA articles onto the surface of a device to protect the surface is to coat a curable composition onto the surface and allow the composition to cure to form a protective layer. However, many conventional coating techniques also suffer from problems similar to those described above, as they may be difficult to apply precisely to surfaces with unusual shapes or sizes.

[0007] One particularly precise coating technique is inkjet printing. Inkjet printing is not only precise, but it also allows curable compositions to be delivered to surfaces without contact, making it suitable for a wide range of surfaces, including those susceptible to damage from other techniques.

[0008] However, when replacing film products with inkjet printing and curing of curable coatings, several properties must be met. Since the coating is used to replace adhesive / film products, the cured coating must possess properties similar to those of the protective film product, such as modulus and toughness. Additionally, like PSA products, the cured coating must be removable from the surface without damaging it or leaving residue. Finally, the curable composition must be inkjet printable for use, meaning it must have properties such as low viscosity. The curable composition must be able to cure by input light without requiring heat, and is expected to cure quickly enough for rapid processing.

[0009] This article discloses inkjet-printable curable compositions that possess the necessary balance of properties for forming a protective layer on a device surface. In addition to inkjet printability and UV curability, the properties include optical transparency to allow inspection of the protected surface, ease of removal without damaging the surface, and desired mechanical properties. Typically, ease of removal is defined as a layer with an adhesive strength of no more than 20 g / in (7.7 N / m), as measured by 180° peel adhesion force. Desired mechanical properties include characteristics similar to conventional plastic films, such as relatively high modulus and toughness.

[0010] In some embodiments, the inkjet-printable curable composition comprises: at least one high-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of at least 60°C; at least one low-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of less than -30°C; at least one crosslinking agent; and at least one photoinitiator. The curable composition is solvent-free and inkjet-printable, having a viscosity of less than 25 centipoise at room temperature. Upon curing to form a 100-micron thick coating, the cured composition has a Tg of at least 50°C as measured by DMA (Dynamic Mechanical Analysis), an adhesion strength to glass of less than 20 g / inch (7.7 N / m) as measured by 180° peel adhesion, a Young's modulus greater than 0.5 gigapascals, and is optically transparent.

[0011] This article also discloses articles containing a layer of a curable composition that can be cured and inkjet printed, and methods for preparing such articles.

[0012] The term "(meth)acrylate" refers to the monomeric acrylate or methacrylate of an alcohol. Acrylates and methacrylate monomers or oligomers are collectively referred to herein as "(meth)acrylate". Materials described as "(meth)acrylate functional" are materials containing one or more (meth)acrylate groups.

[0013] The terms “organosilicon” or “siloxane” are used interchangeably and refer to a unit having a repeating dialkyl or diarylsiloxane (-SiR2O-) unit.

[0014] The terms "room temperature" and "ambient temperature" are used interchangeably, referring to temperatures in the range of 20°C to 25°C.

[0015] The terms "Tg" and "glass transition temperature" are used interchangeably. If measured, unless otherwise specified, the Tg value is determined by dynamic mechanical analysis (DMA) at 1 Hz. Typically, the Tg value of copolymers is not measured; instead, it is calculated using the well-known Fox formula, using the Tg values ​​of the monomer homopolymers provided by the monomer supplier, as understood by those skilled in the art.

[0016] As used herein, the terms “polymer” and “macromolecule” are consistent with their common usage in chemistry. Polymers and macromolecules are composed of many repeating subunits. As used herein, the term “macromolecule” is used to describe a group having multiple repeating units attached to a monomer. The term “polymer” is used to describe the material obtained by a polymerization reaction.

[0017] The term "alkyl" refers to a monovalent group that is a group in an alkane, specifically a saturated hydrocarbon. Alkyl groups can be straight-chain, branched, cyclic, or combinations thereof, and typically have 1 to 20 carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl ester.

[0018] The term "alkylene" refers to a divalent group that is a group of an alkane. Alkylenes can be straight-chain, branched, cyclic, or a combination thereof. Alkylenes typically have 1 to 20 carbon atoms. In some embodiments, alkylenes contain 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The center of the alkylene group can be on the same carbon atom (i.e., an alkylidene group) or on different carbon atoms.

[0019] The terms “radical polymerizable” and “olefinic unsaturated” are used interchangeably and refer to reactive groups containing carbon-carbon double bonds capable of polymerization via a radical polymerization mechanism.

[0020] Unless otherwise specified, the terms "optically transparent" and "visible light transmittance" are used interchangeably and refer to articles, films, or adhesives having high transmittance over at least a portion of the visible light spectrum (about 400 nm to about 700 nm). Typically, optically transparent articles have at least 80% visible light transmittance and less than 10% haze.

[0021] Unless otherwise specified, "optically transparent" means an adhesive or article that has high transmittance and exhibits low haze (typically less than about 5%, or even less than about 2%) over at least a portion of the visible light spectrum (about 400 nm to about 700 nm). In some embodiments, optically transparent articles exhibit haze of less than 1%, or even 0.5%, at a thickness of 50 micrometers. Typically, optically transparent articles have at least 90% visible light transmittance.

[0022] This document discloses curable compositions that are printable and are therefore described as inks. Curable compositions are not necessarily used as inks; that is, they are not necessarily printed and then cured. Curable compositions can be delivered to substrate surfaces in a wide variety of ways, but they are printable, specifically inkjet printable, meaning they possess viscosity and other properties suitable for inkjet printing. The term "inkjet printable" is not a process description or limitation, but a material description, meaning that the curable composition can be inkjet printed, not that the composition must have already been inkjet printed. This is similar to the expression "thermally melt processable," meaning that the composition can be thermally melt processable, but not that the composition has already been thermally melt processable.

[0023] In some embodiments, the curable composition comprises: at least one high-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of at least 60°C; at least one low-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of less than -30°C; at least one crosslinking agent; and at least one photoinitiator. The curable composition is solvent-free and inkjet printable, having a viscosity of less than 25 centipoise at room temperature. When cured to form a 100-micron thick coating, the curable composition has a Tg of at least 50°C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 g / inch (7.7 N / m) as measured by 180° peel adhesion, a Young's modulus greater than 0.5 gigapascals, and is optically transparent. In some embodiments, the coating may be optically transparent.

[0024] Various (meth)acrylates are suitable for at least one high-Tg (meth)acrylate alkyl ester that is free of polar groups and has a homopolymer Tg of at least 60°C. In some embodiments, the high-Tg (meth)acrylate alkyl ester comprises a compound of formula 1:

[0025] Where R 1 It is a hydrogen or methyl group; -(CO)- is a carbonyl group C=O; and R 2 It is an alkyl group containing at least 8 carbon atoms; and it does not contain polar groups.

[0026] In some embodiments, the at least one high-Tg (meth)acrylate alkyl ester comprises a compound of formula 1:

[0027] Where R 1 It is a hydrogen or methyl group; -(CO)- is a carbonyl group C=O; and R 2 It is a cyclic alkyl group containing 10 carbon atoms.

[0028] Examples of suitable high-Tg alkyl methacrylates that do not contain polar groups and have a homopolymer Tg of at least 60°C include dicyclopentyl methacrylate, isobornyl methacrylate, dicyclopentyl methacrylate and 4-tert-butylcyclohexyl methacrylate.

[0029] The curable composition further comprises at least one low-Tg (meth)acrylate alkyl ester that is free of polar groups and has a Tg of less than -30°C. In some embodiments, the low-Tg (meth)acrylate comprises a compound of formula 2:

[0030] Where R 1 It is a hydrogen or methyl group; -(CO)- is a carbonyl group C=O; and R 3 It is an alkyl group containing at least 4 carbon atoms; and it does not contain polar groups.

[0031] In some embodiments, the at least one low-Tg (meth)acrylate alkyl ester comprises a compound of formula 2:

[0032] Where R 1 It is a hydrogen or methyl group; -(CO)- is a carbonyl group C=O; and R 3 It is a cyclic alkyl group containing 8 carbon atoms.

[0033] Examples of suitable low-Tg (meth)acrylate alkyl esters that do not contain polar groups and have a homopolymer Tg of less than -30°C include butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, n-hexyl acrylate, n-octyl acrylate, lauryl acrylate, benzyl acrylate, stearyl acrylate, hexadecyl acrylate, and heptadecanyl acrylate.

[0034] The curable composition also contains at least one crosslinking agent. Crosslinking agents are well understood in the polymer field as multifunctional molecules that link polymer chains together. In the curable ink compositions of the present invention, the crosslinking agent is typically a multifunctional (meth)acrylate.

[0035] Various crosslinking agents are suitable. In some embodiments, the crosslinking agent includes di-(meth)acrylate of formula 3:

[0036] Where R 1 It is a hydrogen or methyl group; -(CO)- is a carbonyl group C=O; and R 4 It is an alkylene group having 4 to 10 carbon atoms.

[0037] Examples of usable polyfunctional (meth)acrylates include, but are not limited to, butylene di(meth)acrylate, hexanediol di(meth)acrylate, octyl glycol di(meth)acrylate, decanediol di(meth)acrylate, and mixtures thereof.

[0038] The curable composition also contains at least one initiator. Typically, the initiator is a photoinitiator, meaning that the initiator is activated by light, typically ultraviolet (UV) light, but other light sources may be used depending on the appropriate selection of the initiator (such as visible light initiators, infrared light initiators, etc.). Therefore, curable ink compositions can typically be cured by UV or visible light (typically UV light). Thus, UV photoinitiators are typically used as initiators. Photoinitiators are well known to those skilled in the art of (meth)acrylate polymerization. Examples of suitable free radical photoinitiators include IRGACURE 4265, IRGACURE 184, IRGACURE 651, IRGACURE 1173, IRGACURE 819, IRGACURE TPO, and IRGACURE TPO-L, which are commercially available from BASF, Charlotte, NC, North Carolina.

[0039] Curable coating compositions may contain additional additives, provided that the additives do not interfere with the coating, curing, or final properties of the curable coating composition. In some embodiments, the curable coating composition further comprises at least one surfactant or wetting agent additive, including silicone-acrylates. Particularly suitable are silicone polyether acrylates, such as TEGO RAD 2100, TEGO RAD 2250, and TEGO RAD 2300, which are commercially available from Evonik Industries under the trade name TEGO RAD. TEGO RAD 2250 is particularly suitable.

[0040] The amount of each component in the curable composition can vary. In some embodiments, the curable composition comprises: 60 to 80 parts by weight of at least one high Tg (meth)acrylate alkyl ester that does not contain polar groups and has a homopolymer Tg of at least 60°C; From 20 to 40 parts by weight of at least one low-Tg (meth)acrylate alkyl ester that does not contain polar groups and has a homopolymer Tg of less than -30°C. At least one crosslinking agent, in amounts of 5 to 30 parts by weight; and At least one photoinitiator, in amounts ranging from 0.1 to 5 parts by weight.

[0041] Each of these components is described in detail above.

[0042] In some embodiments, the curable composition further comprises: At least one organosilicon-acrylate wetting agent, in amounts ranging from 0.1 parts by weight to 1 part by weight.

[0043] This document also discloses articles of manufacture. In some embodiments, the articles of manufacture include: a substrate having a first primary surface and a second primary surface; and a curable coating disposed on at least a portion of the second primary surface of the substrate. The curable coating comprises a curable coating composition that has been coated and cured. The curable coating composition has been described above and comprises: at least one high-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of at least 60°C; at least one low-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of less than -30°C; at least one crosslinking agent; and at least one photoinitiator. The curable composition is solvent-free and inkjet printable, has a viscosity of less than 25 centipoise at room temperature, and, when cured to form a 100-micron thick coating of the curable composition, has a Tg of at least 50°C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 g / in (7.7 N / m), a Young's modulus greater than 0.5 gigapascals, and is optically transparent. In some embodiments, the coating is optically transparent. In some embodiments, the curable coating composition further comprises at least one wetting agent additive, which includes silicone-acrylate.

[0044] The article comprises a substrate having a first primary surface and a second primary surface. The substrate is typically optically transparent. Examples of suitable substrates include glass sheets and polymeric material sheets, such as PMMA (polymethyl methacrylate) and PC (polycarbonate). Glass is a particularly suitable substrate.

[0045] In many implementations, the curable coating has been inkjet-printed onto a second primary surface of the substrate and then photocured to form a cured coating. Inkjet printing and photocuring are well-known processes in the polymer field.

[0046] The coating can have a variety of thicknesses. In some implementations, the coating has a thickness ranging from 25 micrometers to 500 micrometers.

[0047] A method for forming an article is also disclosed. In some embodiments, the method includes: providing a substrate having a first main surface and a second main surface; providing a curable coating composition; inkjet printing the curable coating composition onto the second main surface of the substrate; and photocuring the curable coating composition to form a coating on the second main surface of the substrate.

[0048] The suitable substrate and curable coating composition have been described in detail above. In some embodiments, the substrate comprises glass and the curable coating composition comprises: at least one high-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of at least 60°C; at least one low-Tg (meth)acrylate alkyl ester, which is free of polar groups and has a homopolymer Tg of less than -30°C; at least one crosslinking agent; and at least one photoinitiator. The curable composition is solvent-free and inkjet printable, having a viscosity of less than 25 centipoise at room temperature. When cured to form a coating 100 micrometers thick, the curable composition has a Tg of at least 50°C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 g / inch (7.7 N / m) as measured by 180° peel adhesion, a Young's modulus greater than 0.5 gigapascals, and is optically transparent. In some embodiments, the coating may be optically transparent.

[0049] Curable coating compositions may contain additional additives, provided that the additives do not interfere with the coating, curing, or final properties of the curable coating composition. In some embodiments, the curable coating composition further comprises at least one wetting agent additive, which includes silicone-acrylate.

[0050] The coating can have a variety of thicknesses. In some implementations, the coating has a thickness ranging from 25 micrometers to 500 micrometers.

[0051] In some embodiments, it may be desirable to perform photocuring in a two-step process. In this two-step process, the first step partially cures the curable composition to increase viscosity and helps to form a more uniform coating upon completion of curing. In some embodiments, the first step involves brief exposure to UV radiation in air, and the second step is a longer curing step typically carried out in a nitrogen atmosphere.

[0052] Example

[0053] These embodiments are for illustrative purposes only and are not intended to limit the scope of the appended claims. Unless otherwise specified, all parts, percentages, ratios, etc., in the embodiments and the remainder of the specification are by weight. The following abbreviations are used: RPM = rotational speed per minute; cm = centimeter; in = inch; mm = millimeter; nm = nanometer; min = minute; s = second; pL = picoliter; mW = milliwatt; Hz = hertz; and mJ = millijoule.

[0054]

[0055] Test methods

[0056] Viscosity

[0057] Viscosity was measured using a Brookfield viscometer DVII+ Pro, which features a temperature control unit (25°C), a No. 0 rotor, and controls RPM to a load range of 20% to 60%.

[0058] Inkjet capability

[0059] Inkjetability was determined by observing the shape of the ejected droplets, the direction of the inkjet output through a camera located in the printing press, and nozzle clogging, and by testing continuous on- and off-off inkjet performance. Samples were classified as either "jetable" or "non-jetable".

[0060] Conversion rate

[0061] By 810cm before and after UV curing -1 The conversion rate is measured by the ratio of the FTIR peak areas of the C=C bonds at the C=C bond.

[0062] 180° peel adhesion

[0063] The 180° peel of a 1-inch (2.54 cm) wide sample was tested using an I-mass peel tester at 90 in / min (228 cm / min).

[0064] bending

[0065] The cured sample is bent to 180° to determine if the cured film is broken. If the film is intact, the sample is classified as "acceptable"; if the film is broken, it is classified as "unacceptable".

[0066] Tensile measurement

[0067] Tensile strain and stress were measured using Instron at a crosshead speed of 10 mm / min, according to ASTM D882. The sample dimensions were 0.1 mm thickness × 16 mm (width) × 50 mm (length).

[0068] Dynamic mechanical analysis

[0069] Tg was determined using dynamic mechanical analysis. A Q800 dynamic mechanical analyzer in tension mode was used, and the sample was scanned at 3°C / min from 25°C to 100°C. The sample dimensions were 0.1 mm thickness × 7 mm (width) × 13.5 mm (length).

[0070] Optical Measurement

[0071] Haze and transmittance were measured using a BYK Gardner+ spectrophotometer. Color was measured using a Konica Minolta CM-3700d spectrophotometer.

[0072] Examples E1-E4 and Comparative Examples C1-C12 : A series of printable curable compositions were prepared using the components shown in Table 1 (parts by weight). The components were mixed at 50-100 RPM for 24 hours on a roller mixer. The viscosity and printability of the printable curable compositions were tested (all samples were printable), and the results are shown in Table 1 below.

[0073]

[0074] The curable composition is inkjet printed onto soda-lime silicate or aluminosilicate glass. The inkjet-printed coating is then cured using UV radiation. The printing and curing processes are summarized below.

[0075] Printing and curing Process

[0076] 1. Printing: Unijet inkjet printer (South Korea)

[0077] Printhead: Konica Minolta KM1024i

[0078] Nozzle injection volume: 13pL

[0079] Printing frequency: 2kHz

[0080] Drive voltage: 13.6V

[0081] 2. Curing: UV lamp, Phoseon FJ800 (100x100AC395-1W)

[0082] - Step 1: 395nm 30mJ (50mW×0.6s) in air

[0083] - Step 2: 395nm 3000mJ (600mW×5s) N2 purge chamber for 2min

[0084] The cured compositions were tested according to the test methods shown above. The results are shown in Tables 2-4 below.

[0085]

Claims

1. A curable composition comprising: at least one high Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of at least 60 °C; at least one low Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of less than -30 °C; at least one crosslinker; and at least one photoinitiator, wherein the curable composition is free of solvent and is inkjet printable, has a viscosity of less than 25 centipoise at room temperature, and upon curing to form a 100 micrometer thick coating has a Tg of at least 50 °C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 grams / inch (7.7 N / m) as measured by 180° peel adhesion, a Young’s modulus of greater than 0.5 gigapascals, and is optically clear.

2. The curable composition of claim 1, wherein the at least one high Tg alkyl (meth)acrylate comprises a compound of Formula 1: wherein R 1 is a hydrogen or methyl group; -(CO)- is a carbonyl group C=0; and R 2 is an alkyl group comprising at least 8 carbon atoms; and is free of polar groups.

3. The curable composition of claim 1, wherein the at least one high Tg alkyl (meth)acrylate comprises a compound of Formula 1: wherein R 1 is a hydrogen or methyl group; -(CO)- is a carbonyl group C=0; and R 2 is a cyclic alkyl group comprising at least 10 carbon atoms.

4. The curable composition of claim 1, wherein the at least one low Tg alkyl (meth)acrylate comprises a compound of Formula 2: wherein R is a hydrogen or methyl group; 1 is a hydrogen or methyl group; -(CO)- is a carbonyl group C=0; and R 3 is an alkyl group comprising at least 4 carbon atoms; and is free of polar groups.

5. The curable composition of claim 1, wherein the crosslinker comprises a di(meth)acrylate of Formula 3: wherein R is a hydrogen or methyl group; 1 is a hydrogen or methyl group; -(CO)- is a carbonyl group C=0; and R 4 R is an alkylene group having 4 to 10 carbon atoms.

6. The curable composition of claim 1, wherein the curable composition further comprises at least one wetting agent additive comprising a silicone-acrylate.

7. The curable composition of claim 1, wherein the curable composition comprises: 60 to 80 parts by weight of at least one high Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of at least 60 °C; 20 to 40 parts by weight of at least one low Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of less than -30 °C; 5 to 30 parts by weight of at least one crosslinker; and 0.1 to 5 parts by weight of at least one photoinitiator.

8. The curable composition of claim 8, further comprising: 0.1 to 1 parts by weight of at least one silicone-acrylate wetting agent.

9. An article comprising: a substrate having a first major surface and a second major surface; and a cured coating disposed on at least a portion of the second major surface of the substrate, wherein the cured coating comprises a curable coating composition that has been applied and cured, the curable coating composition comprising: at least one high Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of at least 60°C; at least one low Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of less than -30°C; at least one crosslinker; and at least one photoinitiator, wherein the curable composition is free of solvent and is inkjet printable, has a viscosity of less than 25 centipoise at room temperature, and upon curing to form a 100 micrometer thick coating has a Tg of at least 50°C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 grams / inch (7.7 N / m) as measured by 180° peel adhesion, a Young's modulus of greater than 0.5 GigaPascal, and is optically clear.

10. The article of claim 9, wherein the substrate comprises an optically clear sheet.

11. The article of claim 9, wherein the substrate comprises glass.

12. The article of claim 9, wherein the curable coating has been inkjet printed onto the second major surface of the substrate and photo-cured to form the cured coating.

13. The article of claim 9, wherein the curable coating composition further comprises at least one wetting agent additive comprising a silicone-acrylate.

14. The article of claim 9, wherein the cured coating has a thickness of 25 micrometers to 500 micrometers.

15. A method of forming an article, the method comprising: providing a substrate having a first major surface and a second major surface; providing a curable coating composition comprising: at least one high Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of at least 60°C; at least one low Tg alkyl (meth)acrylate free of polar groups and having a homopolymer Tg of less than -30°C; at least one crosslinker; and at least one photoinitiator, wherein the curable composition is free of solvent and is inkjet printable, has a viscosity of less than 25 centipoise at room temperature, and upon curing to form a 100 micrometer thick coating has a Tg of at least 50°C as measured by DMA (Dynamic Mechanical Analysis), an adhesion to glass of less than 20 grams / inch (7.7 N / m) as measured by 180° peel adhesion, a Young's modulus of greater than 0.5 GigaPascal, and is optically clear; inkjet printing the curable coating composition onto the second major surface of the substrate; and photo-curing the curable coating composition to form a coating on the second major surface of the substrate.

16. The method of claim 15, wherein the substrate comprises an optically clear sheet.

17. The method of claim 15, wherein the substrate comprises glass.

18. The method of claim 15, wherein the curable coating composition further comprises at least one wetting agent additive comprising a silicone-acrylate.

19. The method of claim 15, wherein the coating has a thickness of 25 microns to 500 microns.

20. The method of claim 15, wherein photocuring comprises a two-step curing sequence.

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