KR102395516B1 - Acryl-based adhesive compostion and surface protective film for cover glass comprising the same - Google Patents

Abstract

Disclosed in the present specification is an acryl-based adhesive composition and a surface protective film for cover glass using the same. Since the surface protective film of the present invention realizes a low surface resistance of less than 109 Ω and at the same time shows high reliability under high temperature, high humidity, and thermal shock test conditions, surface damage which may occur during or after a process for manufacturing the cover glass can be effectively prevented. In addition, since the surface protective film of the present invention has high wettability, workability and manufacturing process speed can be improved.

Description

An acrylic pressure-sensitive adhesive composition and a surface protective film for cover glass comprising the same

The present specification relates to an acrylic pressure-sensitive adhesive composition and a surface protection film for cover glass including the same.

Cover glass is a glass provided on the outer surface of the display of the terminal to protect the light emitting body of the display. Recently, as electronic products such as smartphones, integrated computers, and cameras have become smaller and lighter and perform various functions, the cover glass also has anti-fingerprint (Antismudge, AS), anti-reflection (AR), and anti-glare functions as a surface function. (Anti-glare, AG) is added, and when used in a touch screen panel, surface protection and control of surface resistance are also required. Therefore, protection against surface damage that may occur due to external factors during or after the manufacturing process of the cover glass is required. Accordingly, in the case of a surface protection film used in the manufacturing and assembling process of cover glass, high adhesion and transparency to the cover glass are required, as well as excellent in order to prevent the inflow of foreign substances or damage to the product due to static electricity when the film is removed. Peel force, low surface resistance of less than 10 ⁹ Ω, and high reliability that does not leave transitions or stains on the surface of the cover glass even under high temperature, high humidity, and thermal shock conditions are required.

As a surface protection film for cover glass, various types of adhesive protection films such as acrylic, urethane, and silicone are used. However, in the case of the silicone type, it is difficult to realize a surface resistance of less than 10 ⁹ Ω, and there is a problem that stains remain on the surface of the cover glass due to the transfer of siloxane oil. It can cause problems with adhesion. In the case of the urethane type, there is a problem in that reliability is not secured because stains remain on the surface of the cover glass due to unreacted polyols having a relatively low molecular weight compared to the acrylic type. Acrylic type has the advantage of low transition to the surface of the cover glass and easy implementation of surface resistance, but microscopic transition occurs on the surface of the cover glass under high-temperature and high-humidity conditions. There is a problem in that it is impossible to check whether the sensor is operating during the manufacturing process because it affects the ultrasonic sensor. In addition, there is a disadvantage in that manufacturing efficiency is lowered due to low wettability compared to a silicone type film.

Republic of Korea Patent Publication No. 10-2015-0112831

The problem to be solved by the present invention is to realize a surface resistance of less than 10 ⁹ Ω for use in a surface protection film of a cover glass, and at the same time provide high reliability that does not leave a transition on the surface of the cover glass under high temperature, high humidity and thermal shock test conditions. It is to provide an acrylic pressure-sensitive adhesive composition capable of providing high wettability.

An object of the present invention is to provide a surface protection film for a cover glass manufactured using the acrylic pressure-sensitive adhesive composition as described above.

An embodiment of the present invention includes an acrylate resin, a curing agent, a plasticizer and an antistatic agent, based on 100 parts by weight of the acrylate resin, the curing agent is 0.5 to 2.2 parts by weight, the plasticizer is 2.3 to 10 parts by weight and the charging The inhibitor provides an adhesive composition for a cover glass surface protection film comprising 1.2 to 2.2 parts by weight.

One embodiment of the present invention provides a cover glass surface protection film sequentially including a release film, an adhesive layer including a dried product of the pressure-sensitive adhesive composition, a primer layer, and a base film.

The film using the pressure-sensitive adhesive composition according to an embodiment of the present invention realizes high adhesion and surface resistance of less than 10 ⁹ Ω, and at the same time provides high reliability in high temperature, high humidity and thermal shock test conditions during the manufacturing process of cover glass or It is possible to effectively prevent surface damage that may occur after manufacturing. In addition, since it has high wettability, workability and manufacturing process speed can be improved.

1 is a view schematically showing a cross-section of a surface protection film for a cover glass according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention disclosed in the text are illustrated for the purpose of explanation only, and the embodiments of the present invention may be embodied in various forms and should not be construed as being limited to the embodiments described in the text. . The present invention can make various changes and can have various forms, and the embodiments are not intended to limit the present invention to a specific disclosed form, and all changes, equivalents or substitutes included in the spirit and scope of the present invention should be understood as including

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, and one or more other features The possibility of the presence or addition of numbers, steps, acts, components, parts, or combinations thereof is not excluded.

An embodiment of the present invention includes an acrylate resin, a curing agent, a plasticizer and an antistatic agent, based on 100 parts by weight of the acrylate resin, the curing agent is 0.5 to 2.2 parts by weight, the plasticizer is 2.3 to 10 parts by weight and the charging An inhibitor provides an adhesive composition for a cover glass surface protection film comprising 1.2 to 2.2 parts by weight.

In an embodiment, the acrylate resin may include an acrylate copolymer. Specifically, the acrylate copolymer may be a copolymerization product of an acrylate monomer, an unsaturated monomer including at least one of a hydroxyl group and a carboxy group, and a reactive emulsifier. Specifically, the acrylate copolymer may be an acrylate copolymer including at least one repeating unit derived from a monomer selected from the group consisting of acrylate monomers substituted with at least one of a hydroxyl group and a carboxy group.

In one embodiment, the acrylate monomer is methyl acrylate, ethyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, pentyl acrylate, isoamyl acrylate, hexyl acrylate, heptyl acrylic Rate, octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, tetrahydrofurfuryl acrylate, erythritol acrylate, butoxy Ethyl acrylate, ethoxydiethylene glycol acrylate, pentaerythritol acrylate, dierythritol acrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, methoxyethylene glycol acrylate, methoxy polypropylene glycol acrylate, Phenoxy-2-methylethyl acrylate, 2-phenylphenoxy acrylate, 4-phenylphenoxyethyl acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl acrylate, tricyclodecanyl acrylate Late, phenoxyethoxyethyl acrylate, isopropyl acrylate, cyclohexyl acrylate, 2-methylcyclohexyl acrylate, dipentaerythritol acrylate, dicyclopentanyl acrylate, dicyclopentanyloxyethyl acrylate, iso Bornyl acrylate, cyclohexyl acrylate, 2-methylcyclohexyl acrylate, phenyl acrylate, 2-hydroxyethyl acrylate, isobutyl acrylate, caprolactone acrylate, O-phenylphenol ioacrylate, isodecyl acryl Rate, lauryl acrylate, alkyl acrylate, steacrylate, benzyl acrylate, 2-hydroxy acrylate, trimethoxybutyl acrylate, ethyl carbidol acrylate, phenoxyethyl acrylate, 4-hydroxy Butyl acrylate, phenoxy polyethylene glycol acrylate, tetrahydrofuryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-acryloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy -3-phenoxypropyl acrylate and methacrylates thereof may be exemplified, but the present invention is not limited thereto. As an embodiment, the acrylate monomer may be included in an amount of 63 to 77 wt% based on the total weight of the acrylate resin. Specifically, the acrylate monomer according to the embodiment is 63 wt% or more, 64 wt% or more, 65 wt% or more, 66 wt% or more, 67 wt% or more, 68 wt% or more, based on the total weight of the acrylate resin. or more, 69% by weight or more, 70% by weight or more, 71% by weight or more, 72% by weight or more, 73% by weight or more, 74% by weight or more, 75% by weight or more, or 76% by weight or more, and 77% by weight or less , 76 wt% or less, 75 wt% or less, 74 wt% or less, 73 wt% or less, 72 wt% or less, 71 wt% or less, 70 wt% or less, 69 wt% or less, 68 wt% or less, 67 wt% or less , 66% by weight or less, 65% by weight or less, or 64% by weight or less. In an embodiment of the present invention, when the content of the acrylate monomer is out of the above range, the adhesive may not be effectively adhered to the cover glass due to low adhesion.

As an embodiment, the unsaturated monomer including at least one of a hydroxy group and a carboxy group may be included in an amount of 13 to 18 wt%. Specifically, the unsaturated monomer may be included in an amount of 13 wt% or more, 14 wt% or more, 15 wt% or more, 16 wt% or more, or 17 wt% or more, 18 wt% or less, 17 wt% or more based on the total weight of the acrylate resin Weight % or less, 16 wt% or less, 15 wt% or less, or 14 wt% or less may be included. In an embodiment of the present invention, when the content of the unsaturated monomer is out of the above range, it is difficult to secure the desired physical properties in the present invention.

In one embodiment, the reactive emulsifier may be an anionic emulsifier containing an allyl group. Specifically, the reactive emulsifier participates in radical polymerization as an anionic emulsifier containing an allyl group such as acryloyl, methacryloyl, etc., and may serve to strengthen the binding force with the antistatic agent. . As an embodiment, the reactive emulsifier may be included in an amount of 8 to 12% by weight based on the total weight of the acrylate resin. Specifically, the reactive emulsifier may be included in an amount of 8% by weight or more, 9% by weight or more, 10% by weight or more, or 11% by weight or more, 12% by weight or less, 11% by weight or less, 10% by weight based on the total weight of the acrylate resin It may be included in wt% or less or 9 wt% or less. In an embodiment of the present invention, when the content of the reactive emulsifier is out of the above range, it is difficult to secure the desired physical properties in the present invention.

As an embodiment, the acrylate copolymer may be an acrylate copolymer having a high molecular weight and a narrow molecular weight distribution within the limits capable of realizing surface resistance and desired adhesive force. Specifically, the weight average molecular weight (Mw) of the acrylate copolymer may be 1,000,000 to 1,500,000.

As an embodiment, the weight ratio of the acrylate monomer, the unsaturated monomer including at least one of a hydroxyl group and a carboxyl group and the reactive emulsifier may be 63 to 77: 13 to 18: 8 to 12. When included in the above ratio, it is possible to provide a pressure-sensitive adhesive composition that has suitable adhesive strength, re-peelability and antistatic properties, and does not leave contamination or residue after re-peelling.

In addition, the acrylate resin is 80 wt% or more, 81 wt% or more, 82 wt% or more, 83 wt% or more, 84 wt% or more, 85 wt% or more, 86 wt% or more, 87 wt% based on the total weight of the composition or more, 88% by weight or more, 89% by weight or more, 90% by weight or more, 91% by weight or more, 92% by weight or more, 93% by weight or more, or 94% by weight or more, 95% by weight or less, 94% by weight or less , 93 wt% or less, 92 wt% or less, 91 wt% or less, 90 wt% or less, 89 wt% or less, 88 wt% or less, 87 wt% or less, 86 wt% or less, 85 wt% or less, 84 wt% or less , 83 wt% or less, 82 wt% or less, or 81 wt% or less may be included.

In an embodiment, the curing agent may be at least one selected from the group consisting of an isocyanate compound, an epoxy compound, and a metal compound. Specifically, the isocyanate compound is not limited as long as it has an isocyanate group (NCO-) in the molecule, and for example, aromatic diisocyanate such as torylene diisocyanate, xylene diisocyanate, and hexadiisocyanate. Nate (hexamethylene diisocyanate), hexamethylene diisocyanate, or an adduct of these and a compound having a hydroxyl group may be included. As an embodiment, the curing agent may be included in an amount of 0.5 to 2.2% by weight based on 100 parts by weight of the acrylate resin. Specifically, the curing agent is 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, 1 part by weight or more, 1.1 parts by weight or more, based on 100 parts by weight of the acrylate resin; 1.2 parts by weight or more, 1.3 parts by weight or more, 1.4 parts by weight or more, 1.5 parts by weight or more, 1.6 parts by weight or more, 1.7 parts by weight or more, 1.8 parts by weight or more, 1.9 parts by weight or more, 2 parts by weight or more, or 2.1 parts by weight or more. 2.2 parts by weight or less, 2.1 parts by weight or less, 2.0 parts by weight or less, 1.9 parts by weight or less, 1.8 parts by weight or less, 1.7 parts by weight or less, 1.6 parts by weight or less, 1.5 parts by weight or less, 1.4 parts by weight or less, 1.3 It may be included in parts by weight or less, 1.2 parts by weight or less, 1.1 parts by weight or less, 1.0 parts by weight or less, 0.9 parts by weight or less, 0.8 parts by weight or less, 0.7 parts by weight or less, or 0.6 parts by weight or less. When the curing agent is included in an amount of less than 0.5 parts by weight, crosslinking in the pressure-sensitive adhesive composition becomes insufficient, so that it is difficult to secure reliability in a high-temperature, high-humidity environment or thermal shock, and residues may remain on the cover glass. Peelability may not be obtained.

In one embodiment, the plasticizer may include an ester compound. For example, the plasticizer may include a terephthalate-based, adipate-based or phthalate-based ester compound, but is not limited thereto. As an embodiment, the plasticizer may be included in an amount of 2.3 to 10 parts by weight based on 100 parts by weight of the acrylate resin. Specifically, the plasticizer is 2.3 parts by weight or more, 2.4 parts by weight or more, 2.5 parts by weight or more, 2.6 parts by weight or more, 2.7 parts by weight or more, 2.8 parts by weight or more, 2.9 parts by weight or more, based on 100 parts by weight of the acrylate resin; 3 parts by weight or more, 3.1 parts by weight or more, 3.2 parts by weight or more, 3.3 parts by weight or more, 3.4 parts by weight or more, 3.5 parts by weight or more, 3.6 parts by weight or more, 3.7 parts by weight or more, 3.8 parts by weight or more, 3.9 parts by weight or more, 4 parts by weight or more, 4.1 parts by weight or more, 4.2 parts by weight or more, 4.3 parts by weight or more, 4.4 parts by weight or more, 4.5 parts by weight or more, 4.6 parts by weight or more, 4.7 parts by weight or more, 4.8 parts by weight or more, 4.9 parts by weight or more, 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, or 9 parts by weight or more, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7.9 parts by weight or less; 7.8 parts by weight or less, 7.7 parts by weight or less, 7.6 parts by weight or less, 7.5 parts by weight or less, 7.4 parts by weight or less, 7.3 parts by weight or less, 7.2 parts by weight or less, 7.1 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less; It may be included in an amount of 5 parts by weight or less, 4 parts by weight or less, or 3 parts by weight or less. When the plasticizer is included in an amount of less than 2.3 parts by weight based on 100 parts by weight of the acrylate resin, the wettability of the film including the plasticizer may be very low, and when it is included in more than 10 parts by weight, the content of other components is relatively low. Adhesive force, peeling force, antistatic effect, etc. may be reduced.

As an embodiment, the antistatic agent is an additive-type antistatic agent for expressing an antistatic effect, and may lower the electrical resistance of the acrylate copolymer and express the antistatic effect. The antistatic agent is not particularly limited as long as it has antistatic performance, and as an example, one or more selected from the group consisting of lithium cations, ammonium-based cations, polysiloxane-based cations and glycol ether anions may be provided. As an embodiment, at least one selected from the group consisting of a conductive polymer, a metal salt having a metal ion, an ionic liquid, a carbon material, and a surfactant may be used. Specifically, the conductive polymer is polyethylene dioxythiophene (PEDOT, polyethylene dioxythiophene), polyacetylene, poly (p-phenylene vinylene) (Poly (p-phenylene vinylene)), poly (p-phenylene) (Poly(p-phenylene)), poly(thienylene vinylene), polythiophene, polyaniline, polyisothianaphthene, polypyrrole, and For example, at least one selected from the group consisting of poly(p-phenylenesulfide), etc. The metal salt is a lithium salt, lithium imide, and lithium amide ( lithium amide) and potassium salt, etc. Examples of the ionic liquid include pyridine imide, etc. The carbon material includes carbon black, graphite, etc. (graphite), graphene (graphene), carbon nanotubes (CNT, carbon nano tube), carbon nanofiber (CNF, carbon nano fiber), etc. may be exemplified at least one selected from the group consisting of, etc. The surfactant is sulfonic acid salt, quaternary ammonium salt, lauryl dimethylbenzyl ammonium salt, etc. As an example, the antistatic agent may be included in an amount of 1.2 to 2.2 parts by weight based on 100 parts by weight of the acrylate resin. In the case of a surface protection film for glass, an appropriate level of surface resistance is required under the conditions of 10 ⁹ Ω or less. By including the inhibitor in the range of 1.2 to 2.2 parts by weight, the surface resistance is 10 ⁸ to 10 ⁹ It can be expressed at the Ω level. In addition, when the antistatic agent is included in an amount exceeding 2.2 parts by weight, contamination may occur on the surface of the cover glass.

In one embodiment, the pressure-sensitive adhesive composition may further include a solvent, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, an adhesion enhancer, a UV stabilizer, an antioxidant, and the like as an additive, if necessary. The specific type or content of the additive is not limited, and may be appropriately adjusted according to the purpose of the user.

An embodiment of the present invention may provide a cover glass surface protection film including the pressure-sensitive adhesive composition. 1 is a cross-sectional view showing a cross section of a cover glass surface protection film according to the present invention. Referring to FIG. 1 , as an embodiment, the cover glass surface protection film may sequentially include a base film 1 , a primer layer 2 , an adhesive layer 3 , and a release film 4 .

As an embodiment, the base film is a film that primarily protects the surface of the cover glass from the outside, and any film used in the art is not limited to the type and may be used. As an embodiment, the base film may have a high elastic modulus, a small hygroscopic expansion coefficient, and a small linear expansion coefficient. As an embodiment, the tensile strength of the base film may be 22 kgf/mm ² or more in the MD direction (width direction) and 30 kgf/mm ² or more in the TD direction (length direction). As an embodiment, the elongation of the base film may be less than 250% in the MD direction and less than 150% in the TD direction. As an embodiment, the heat shrinkage of the base film may be 1.5% or less at 150°C. In one embodiment, the base film may be a base material including a polymer component. For example, the high-hardness film including the polymer component is a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, or polybuthylene terephthalate, and a polycarbonate film. , a polyether sulfone-based film, a polyethylene film, a polypropylene film, a polyolefin-based film, or a combination thereof. In one embodiment, the thickness of the base film may be 25 to 100 μm. Specifically, the thickness of the base film is 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 55 μm or more, 60 μm or more, 65 μm or more, 70 μm or more, 75 μm or more. or more, 80 μm or more, 85 μm or more, 90 μm or more, or 95 μm or more, and 100 μm or less, 95 μm or less, 90 μm or less, 85 μm or less, 80 μm or less, 75 μm or less, 70 μm or less, 65 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, or 30 μm or less. The thickness of the base film may be applied differently depending on the shape of the housing of the electronic device in which the film is used. For example, a film used for a cover glass having a curved surface can be stably attached as the thickness decreases.

As an embodiment, the primer layer may include, without limitation, any compound capable of maintaining the adhesion of the pressure-sensitive adhesive composition of the pressure-sensitive adhesive layer by strengthening the surface tension between the two layers by being positioned between the base film and the pressure-sensitive adhesive layer. As an embodiment, the primer layer may be coated on one surface of the base film, and for example, a composition including at least one selected from among acrylic, urethane, silicone, and epoxy compounds may be coated. As an embodiment, the primer layer may be corona-treated or CO ₂ plasma-treated on one surface of the base film. In one embodiment, the thickness of the primer layer may be 0.2 to 1 μm. If the thickness of the primer layer is less than 0.2 μm, it cannot act as a primer, and if it exceeds 1 μm, it may negatively affect the adhesion of the film.

As an embodiment, the pressure-sensitive adhesive layer may include a dried product of the pressure-sensitive adhesive composition according to the above-described embodiments of the present invention, and the specific configuration of the pressure-sensitive adhesive composition is as described above. In an embodiment, the thickness of the adhesive layer may be 10 to 30 μm. Specifically, the thickness of the adhesive layer is 10 μm or more, 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, 16 μm or more, 17 μm or more, 18 μm or more, 19 μm or more, 20 μm or more. or more, 21 μm or more, 22 μm or more, 23 μm or more, or 24 μm or more, and 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm can be less than, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, or 11 μm or less there is. If the thickness of the adhesive layer is less than 10 μm, the adhesive strength and wettability of the film may be reduced, and if the thickness is more than 30 μm, the surface resistance and peelability may deteriorate, and the adhesive may be transferred when the film is removed from the cover glass.

As an embodiment, the release film is for protecting the pressure-sensitive adhesive layer, and any material having a low surface resistance and suitable release property for the pressure-sensitive adhesive layer may be used without limitation. For example, the release film may be a fluorine release film or a release treatment film. The release agent included in the release film is not particularly limited, but may be a silicone-based release agent or a wax-based release agent. In one embodiment, the thickness of the release film may be 19 to 100 μm. Specifically, the thickness of the variant name is 19 μm or more, 20 μm or more, 21 μm or more, 22 μm or more, 23 μm or more, 23 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more. can be greater than or equal to 50 μm, greater than 55 μm, greater than 60 μm, greater than 65 μm, greater than 70 μm, greater than 75 μm, greater than 80 μm, greater than 85 μm, greater than 90 μm, greater than or equal to 95 μm, 100 μm or greater, greater than 95 μm or less, 90 µm or less, 85 µm or less, 80 µm or less, 75 µm or less, 70 µm or less, 65 µm or less, 60 µm or less, 55 µm or less, 50 µm or less, 45 µm or less, 40 µm or less, 35 µm or less, 30 μm or less, 25 μm or less, or 20 μm or less. If the thickness of the release film is less than 19 μm, the film may be broken by high tension during the punching process, thereby reducing processability.

The surface protection film for a cover glass according to an embodiment of the present invention may be manufactured by the following method. In one embodiment, coating the composition for a primer layer on one surface of the base film or corona treatment or CO ₂ plasma treatment to form a primer layer; forming a pressure-sensitive adhesive layer by coating the pressure-sensitive adhesive composition on the other surface of the primer layer; and coating a release agent on the other side of the adhesive layer to form a release film.

In one embodiment, the step of coating the composition for the primer layer is not limited as long as it is a method commonly used in the art, but for example, gravure coating, Mayer bar coating, slot die coating, air knife coating, doctor knife coating, bar coater It may include drying and curing through a thermal curing and/or UV curing process after coating through a coating process or the like.

As an embodiment, the step of forming the adhesive layer is not limited as long as it is a method commonly used in the art, but for example, a step of drying and curing after coating using a die coater, a nip coater, a gravure roller, a comma coater, etc. may include

As an embodiment, the step of forming the release film is not limited as long as it is a method commonly used in the art, but for example, gravure coating, Mayer bar coating, air knife coating and doctor knife coating process, etc. to apply the release agent to the release base film Then, it may include a step of drying and curing through a thermal curing and / or ultraviolet curing process.

The surface protection film according to embodiments of the present invention may be attached to at least one of the front and rear surfaces of the cover glass by including the above-described acrylic adhesive layer, and in an embodiment, the film may be 7 to 16 gf/25 mm can show the adhesion of As an embodiment, the film exhibits a release peeling force of 3 gf/25 mm or less and has a surface resistance of less than 10 ⁹ Ω. It can be effectively peeled off. The surface protection film according to embodiments of the present invention has excellent reliability even at high temperature, high humidity and thermal shock, and exhibits high wettability at a level similar to that of a silicone type film, thereby shortening the manufacturing process time. In addition, the surface protection film according to an embodiment of the present invention may have transparency, for example, a light transmittance (TT) of the film may be 89% or more, and a haze may be 3% or less. Accordingly, the surface protection film according to an embodiment of the present invention may be used for a cover glass of an electronic device such as a TV, a computer, or a portable mobile display device. In particular, it can be easily used for cover glass including a flexible type or including a touch sensor.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not to be construed as being limited by these examples.

[Test Example 1]

Examples and Comparative Examples of the surface protection film for cover glass were respectively prepared according to the following method.

Specifically, a primer layer is formed on top of a polyethylene terephthalate film (thickness: 36 μm) as a base film according to a conventional method used in the art, and an adhesive composition is coated on the primer layer, and dried and cured at 120° C. or higher. to prepare an adhesive layer (thickness: 20 μm). In this case, the adhesive composition includes ethyl acrylate, an unsaturated monomer (4-hydroxy acrylate), a reactive emulsifier (methacryloyl), a curing agent (hexamethylene diisocyanate), a plasticizer (adipate-based ester compound), and an antistatic agent (pyridineimide) was added to a solvent and reacted. A release-treated polyethylene terephthalate film was laminated on the adhesive layer.

Table 1 below shows the weight ratios of the components respectively included in the Examples and Comparative Examples prepared above.

ethyl acetate unsaturated monomer reactive emulsifier hardener plasticizer antistatic agent Example 1 65 15 10 1.0 5 1.5 Comparative Example 1 65 15 10 0.5 5 1.5 Comparative Example 2 65 15 10 2.0 5 1.5 Comparative Example 3 65 15 10 3.0 5 1.5 Comparative Example 4 65 15 10 1.0 2 1.5 Example 2 65 15 10 1.0 7 1.5 Comparative Example 5 65 15 10 1.0 5 1.0 Comparative Example 6 65 15 10 1.0 5 2.0

The physical properties of Examples 1 and 2 and Comparative Examples 1 to 5 prepared above were evaluated by the following method, and the results are shown in Table 2.

Adhesion test test (CKP-5000)

① Cut the film to be tested into 25mm in width x 250mm in length in the machine direction.

② Measure the release peeling force while peeling at a peeling speed of 300m/min in the 180° Peel Test method using an adhesive force meter (CKP-5000).

③ Lay the film tested for release peeling on a glass or SUS (Special Use Steel) plate that has been washed and dried using an automatic laminating machine (2kg load) and stored at 25±2℃ for 30 minutes.

④ Measure the adhesive strength of other parts of the film while peeling it at a peeling rate of 300mm/min in the 180° Peel Test method using an adhesive force meter (CKP-5000).

Peel force test (CKP-5000)

① Lightly attach the standard tape (TESA7475) with a width of 25mm x a length of 250mm to the test film in the machine direction.

② After reciprocating the prepared film using a FINAT test roller (2 kg load) at a speed of 10 mm/sec, press the film between a flat metal plate or glass plate for sufficient compression of the film and the standard tape at a pressure of 70 g/cm2. Store at 23±2℃ for 20 hours.

③ After storage, remove the pressure and conduct the test after 4 hours at a temperature of 23±2℃. The test is measured by fixing the film to a jig and peeling the standard tape in a 180° direction at a speed of 300 mm/min.

Optical Characteristics (NDH-2000)

① Cut the film under test into 50mm x 50mm in the left, middle, and right directions in the transverse direction.

② Fix the film to the measuring device in the same direction to measure transmittance (T.T) and haze.

③ Record the result.

Surface resistance (TREK-152-1)

① Measure 3 points of the film under test in the left, middle, and right directions in the full width and lateral direction.

② Place the prepared film on the glass and measure the adhesive side of the film with a surface resistance meter.

③ The standard is 100V, Ω standard.

Thermal shock test (TS500, JEIO TECH)

① Prepare the electronic device metal housing and the test target film suitable for its size.

② Lay the prepared film on the metal housing and conduct a thermal shock test.

③ Test conditions are -40℃/30min ~ 85℃/30min, 72cycle.

High-temperature, high-humidity test (JEIO TECH thermo-hygrostat)

① Prepare the electronic device metal housing and the test target film suitable for its size.

② Lay the prepared film on the metal housing and conduct a thermal shock test.

③ Test conditions are 50℃/95%, 72hr.

Wetting Comparison

After preparing a film to be tested in a size of 50 mm in width X 200 mm in length, it was placed on bare glass at the same time and the speed of adhering to the glass was compared. The faster the speed, the better the wettability was evaluated, and it was described as ◎ > ○ > △ > X.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 2 Comparative Example 5 Comparative Example 6 adhesiveness
(gf/25mm) 11.2 21.3 6.4 5.2 14.1 9.9 10.8 10.3 peel force (
gf/25mm) 1.2 1.4 1.0 1.1 1.3 1.2 11 1.4 Haze (%) 2.4 2.6 2.3 2.2 2.4 2.1 2.6 2.9 Transmittance (%) 90.5 90.4 90.6 90.5 90.1 90.1 89.9 89.8 surface resistance
(Ω) 7.22*10 ⁸ 7.32*10 ⁸ 6.83*10 ⁸ 7.71*10 ⁸ 7.74*10 ⁹ 7.16*10 ⁸ 6.22*10 ⁹ 2.61*10 ⁸ Sensor error OK OK OK OK OK OK OK NG transition
(thermal shock / high temperature and high humidity) OK NG OK OK OK OK OK NG wettability ◎ ○ ◎ ◎ △ ◎ - - note Excellent in all properties ReliabilityNG
smear Adhesion to curved surfaces NG A.F/haze treatment surface adhesion NG Wettability NG Excellent in all properties surface resistance NG Sensor error/reliability NG

From the results of Table 2, it can be confirmed that the exemplary embodiment of the present invention achieved all of the target physical properties as summarized in Table 3 below. That is, the pressure-sensitive adhesive composition according to an embodiment of the present invention and the surface protection film prepared using the same show an appropriate level of adhesion without any traces of contamination of the pressure-sensitive adhesive even after being attached to the glass and then peeled off again, and the surface resistance value is also at the level of 10 ¹⁰ Ω. As a result, it can be confirmed that the surface resistance value and the peeling electrification effect are secured at a level that does not cause any problems in touch recognition. In addition, it has secured reliability under high temperature, high humidity and thermal shock conditions, and has high wettability similar to that of a silicone type adhesive film, so it can be confirmed that workability and manufacturing process speed can be improved.

unit target properties adhesiveness (gf/25mm) 11±2 release peeling force (gf/25mm) 3 or less Haze % over 89 T.T. % 3 or less surface resistance Ω less than 10 ⁹ thermal shock Pass/Fail Pass high temperature and humidity Pass/Fail Pass sensor error Pass/Fail Pass wettability ◎ > ○ > △ ◎

1: base film
2: Primer layer
3: adhesive layer
4: release film

Claims (14)

release film;
A pressure-sensitive adhesive layer comprising a dried product of the pressure-sensitive adhesive composition;
primer layer; and
base film;
It is a cover glass surface protection film comprising sequentially,
The pressure-sensitive adhesive composition includes an acrylate resin, a curing agent, a plasticizer and an antistatic agent,
Based on 100 parts by weight of the acrylate resin, the curing agent is included in an amount of 0.6 to 2.2 parts by weight, the plasticizer is 2.3 to 10 parts by weight, and the antistatic agent is 1.2 to 2.2 parts by weight,
The acrylate resin includes a copolymerization product of an acrylate monomer, an unsaturated monomer containing at least one of a hydroxyl group and a carboxyl group, and a reactive emulsifier, and an unsaturated monomer containing at least one of the acrylate monomer, a hydroxyl group and a carboxyl group and a reactive emulsifier. The weight ratio is 63 to 77: 13 to 18: 8 to 12,
The surface resistance of the cover glass surface protection film is less than 10 ⁹ Ω,
The adhesive strength of the cover glass surface protection film is 7 to 16 gf/25mm,
The release peeling force of the cover glass surface protection film is 3 gf / 25mm or less,
Cover glass surface protection film. delete delete The film of claim 1 , wherein the reactive emulsifier comprises an anionic emulsifier comprising an allyl group. The film of claim 1, wherein the curing agent is at least one selected from the group consisting of an isocyanate compound, an epoxy compound, and a metal compound. The film according to claim 1, wherein the plasticizer comprises a terephthalate-based, adipate-based or phthalate-based ester compound. The film of claim 1, wherein the antistatic agent comprises at least one selected from the group consisting of lithium cations, ammonium-based cations, polysiloxane-based cations and glycol ether anions. delete According to claim 1, The thickness of the adhesive layer is 10 to 30㎛, the film. delete delete delete The film of claim 1 , wherein the film has a light transmittance of 89% or more and a haze of 3% or less. The film of claim 1 , wherein the film is for adhering to at least one of a front surface and a rear surface of a cover glass.

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