Adhesive and protective film comprising same

Abstract

Provided are an adhesive and a protective film comprising the same, in which the adhesive comprises: a resin adhesive comprising an acrylic polymer and a carboxylic acid; a metal chelate hardener; and an epoxy-based hardener.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2023 - 0195374, filed with the Korean Intellectual Property Office on December 28, 2023, the entire contents of which are incorporated herein by reference. Technical field

[0003] The present disclosure relates to an adhesive and a protective film including the adhesive. Background art

[0004] With the development of information technology, the importance of display devices as a connection medium between users and information is becoming prominent. Products such as display devices may include a protective film for protecting the surface of the product. The protective film may be formed by applying an adhesive to a protective substrate member and then attaching the protective substrate member to the product.

[0005] In this case, since the adhesive is attached to the product, it is difficult to remove the adhesive from the product. If the adhesive is not removed from the product, it may be difficult to remove the protective film when the product is discarded. If the protective film is not removed from the product, it may be difficult to recycle the protective film. Summary of the invention

[0006] Aspects of the present disclosure aim to provide an adhesive that can be more easily removed from a product and a protective film including the adhesive.

[0007] Another aspect of the present disclosure aims to provide a recyclable protective film and an adhesive having dissociability such that the protective film can be recycled.

[0008] An adhesive according to an embodiment of the present disclosure includes: a resin binder including an acrylic polymer and a carboxylic acid; a metal chelate hardener; and an epoxy - based hardener.

[0009] According to an embodiment, the carboxylic acid may be included in an amount of 10 weight percent (wt%) to 30 wt% relative to the entire composition of the adhesive.

[0010] According to an embodiment, the carboxylic acid may be included in an amount greater than 20 wt% and equal to or less than 30 wt% relative to the entire composition of the adhesive.

[0011] According to an embodiment, the carboxylic acid may react with the acrylic polymer, and at least one carboxyl group of the carboxylic acid may be incorporated into the acrylic polymer.

[0012] According to an embodiment, the carboxylic acid may include acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid.

[0013] According to an embodiment, the metal chelate hardener may be included in an amount of 30 wt% to 60 wt% relative to the entire composition of the adhesive.

[0014] According to an embodiment, the metal chelate hardener may include at least one of an aluminum chelate-based hardener, a titanium chelate-based hardener, and a zirconium chelate-based hardener, wherein the aluminum chelate-based hardener may include at least one of aluminum triethylacetoacetate, aluminum diisopropoxide ethylacetoacetate, aluminum triacetylacetonate, and aluminum acetylacetonate, the titanium chelate-based hardener may include at least one of titanium isopropoxide, titanium ethylacetoacetate, titanium butylacetoacetate, and titanium acetylacetonate, and the zirconium chelate-based hardener may include at least one of zirconium 2-ethylhexanoate, zirconium acetylacetonate, and zirconium acetylacetonate.

[0015] According to an embodiment, the epoxy-based hardener may be included in an amount of 0.5 wt% to 2 wt% relative to the entire composition of the adhesive.

[0016] According to an embodiment, the epoxy-based hardener may be a polyfunctional epoxy-based hardener.

[0017] According to an embodiment, the resin binder may have a weight average molecular weight of 8,000 to 150,000.

[0018] An adhesive according to another embodiment of the present disclosure includes: a resin binder including an acrylic polymer and a carboxylic acid; a metal chelate hardener; and an isocyanate-based hardener, and the carboxylic acid is included in an amount of 10 wt% to 30 wt% relative to the entire composition of the adhesive.

[0019] According to an embodiment, the isocyanate-based hardener may be included in an amount of 0.5 wt% to 2 wt% relative to the entire composition of the adhesive, and the isocyanate-based hardener may be a polyfunctional isocyanate-based hardener.

[0020] According to an embodiment, the metal chelate hardener may be included in an amount of 30 wt% to 60 wt% relative to the entire composition of the adhesive.

[0021] A protective film according to another embodiment of the present disclosure includes: a substrate layer and an adhesive applied on the substrate layer, and the adhesive includes: a resin binder including an acrylic polymer and a carboxylic acid; a first hardener; and a second hardener.

[0022] According to an embodiment, the substrate layer may include at least one of polyethylene terephthalate, polyurethane, polyethylene, polyimide, polybutylene terephthalate, or polyethylene naphthalate.

[0023] According to an embodiment, the carboxylic acid may be included in an amount of 10 wt% to 30 wt% relative to the entire composition of the adhesive.

[0024] According to an embodiment, the first hardener may be a metal chelate hardener, and the metal chelate hardener may be included in an amount of 30 wt% to 60 wt% relative to the entire composition of the adhesive.

[0025] According to an embodiment, the metal chelate hardener may include at least one of an aluminum chelate-based hardener, a titanium chelate-based hardener, and a zirconium chelate-based hardener, wherein the titanium chelate-based hardener may include at least one of aluminum triethylacetoacetate, aluminum diisopropoxide ethylacetoacetate, aluminum acetylacetonate, and aluminum acetylacetonate, the titanium chelate-based hardener may include at least one of titanium isopropoxide, titanium ethylacetoacetate, titanium butylacetoacetate, and titanium acetylacetonate, and the zirconium chelate-based hardener may include at least one of zirconium 2-ethylhexanoate, zirconium acetylacetonate, and zirconium acetylacetonate.

[0026] According to an embodiment, the second hardener may be a polyfunctional epoxy-based hardener, and the epoxy-based hardener may be included in an amount of 0.5 wt% to 2 wt% relative to the entire composition of the adhesive.

[0027] According to an embodiment, the second hardener may be a polyfunctional isocyanate-based hardener, and the isocyanate-based hardener may be included in an amount of 0.5 wt% to 2 wt% relative to the entire composition of the adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated into and constitute a part of this specification. The drawings illustrate embodiments of the present invention and, together with the description, are used to explain the principles of the present invention.

[0029] Figure 1 is a cross-sectional view schematically illustrating a protective film according to the present disclosure;

[0030] Figure 2 is a cross-sectional view schematically illustrating a display device provided with a protective film according to the present disclosure. DETAILED DESCRIPTION

[0031] Since the present disclosure allows for various changes and multiple embodiments, specific embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present disclosure to a particular mode of practice, and it should be understood that all modifications, equivalents, and alternatives that do not depart from the spirit and scope of the present disclosure are encompassed therein.

[0032] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present disclosure, the first element discussed below may be referred to as the second element. Similarly, the second element may also be referred to as the first element.

[0033] In the present disclosure, singular expressions are intended to also include plural expressions unless the context clearly indicates otherwise. The terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting. As used herein, "a", "an", "the", and "at least one" do not denote a limitation of quantity and are intended to include both the singular and the plural, unless the context clearly indicates otherwise. For example, "an element" has the same meaning as "at least one element" unless the context clearly indicates otherwise. "At least one" should not be construed as limiting "a" or "an". "Or" means "and / or". As used herein, the term "and / or" includes any combination and all combinations of one or more of the associated listed items. Throughout the disclosure, the expression "at least one of a, b, and c" means only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variants thereof.

[0034] It should be further understood that the terms “comprise,” “include,” or “have” and the like used in the present disclosure specify the presence of the stated features, integers, steps, operations, elements, components, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. Further, when a first portion such as a layer, film, region, plate, etc. is on a second portion, the first portion may not only be “directly” “on” the second portion, but also a third portion may be interposed between the first portion and the second portion. Further, in the present disclosure, when a first portion such as a layer, film, region, plate, etc. is formed on a second portion, the direction in which the first portion is formed is not limited to the upward direction of the second portion, but may include the side or downward direction of the second portion. Conversely, when a first portion such as a layer, film, region, plate, etc. is under a second portion, the first portion may not only be “directly” “under” the second portion, but also a third portion may be interposed between the first portion and the second portion.

[0035] The present disclosure relates to an adhesive and a protective film including the adhesive. The adhesive according to the present disclosure can be applied to a protective film for protecting the surface of a display device or the like, and can be used to attach the protective film to the display device or the like. Further, the adhesive according to the present disclosure can be used as an adhesive for attaching components adjacent to the display device to each other. This will be described with reference to the drawings hereinafter.

[0036] The adhesive according to the present disclosure may include a resin binder and a hardener.

[0037] The adhesive according to the present disclosure is characterized in that it can dissociate (e.g., dissociate in water) and has high reliability (e.g., high durability) at high temperature (e.g., a temperature higher than 85° C.) and high humidity (e.g., a humidity higher than 85%). Each component will be described hereinafter.

[0038] The resin binder may include an acrylic polymer and a carboxylic acid.

[0039] For example, the acrylic polymer may include a polymer obtained by polymerizing acrylic monomers such as ethyl acrylate, n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, n-dodecyl acrylate, n-tridecyl acrylate, n-tetradecyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 6-hydroxyhexyl acrylate, 8-hydroxyoctyl acrylate, 10-hydroxydecyl acrylate, 12-hydroxylaurate acrylate, and [4-(hydroxymethyl)cyclohexyl]methyl acrylate. However, the present disclosure is not limited thereto, and the acrylic polymer may be one of various types of acrylic polymers known in the art.

[0040] For example, the carboxylic acid may include acetic acid, formic acid, citric acid, benzoic acid, lactic acid, maleic acid, acrylic acid, propylene glycol monoacrylate, β-acryloyloxypropionic acid, etc. However, the present disclosure is not limited thereto, and the carboxylic acid may be one of various types of carboxylic acids known in the art.

[0041] According to an embodiment, the acrylic polymer may be included in an amount of 8 weight percent (wt%) to 59.5 wt% relative to the entire composition of the adhesive. However, the present disclosure is not limited thereto.

[0042] According to an embodiment, the carboxylic acid may be included in an amount of 10 wt% to 30 wt% relative to the entire composition of the adhesive. According to an embodiment, the carboxylic acid may be included in an amount greater than 20 wt% and equal to or less than 30 wt% relative to the entire composition of the adhesive. According to an embodiment, the carboxylic acid may be included in an amount of 21 wt% to 25 wt% relative to the entire composition of the adhesive. According to an embodiment, the carboxylic acid may be included in an amount of 23 wt% relative to the entire composition of the adhesive.

[0043] The carboxylic acid may react with the acrylic polymer, and at least one carboxyl group of the carboxylic acid may be incorporated into the acrylic polymer chain. In the present disclosure, the reaction in which the carboxyl group of the carboxylic acid is incorporated into the acrylic polymer is not limited to specific examples, and synthetic reactions known in the art may be used.

[0044] The carboxyl group may be a reactive group containing an oxygen atom bonded to a hydrogen atom, and hydrogen ions may be generated when the carboxyl group reacts with water. Therefore, when the adhesive reacts with water, the adhesive according to the present disclosure may dissociate because the acrylic polymer contains carboxyl groups.

[0045] According to an embodiment, the resin binder may have a weight-average molecular weight of 8,000 to 150,000. When the weight-average molecular weight of the resin binder is less than 8,000 or greater than 150,000, the dissociability of the adhesive may be reduced.

[0046] The hardener may include a first hardener and a second hardener. According to an embodiment, the first hardener may be a metal chelate hardener. According to an embodiment, the second hardener may be an epoxy-based hardener or an isocyanate-based hardener.

[0047] The hardener may increase the adhesiveness of the adhesive. The hardener may increase the reliability of the adhesive. For example, the hardener may cure (e.g., thermally cure or photocure) the resin binder, increase the adhesiveness of the adhesive, and reduce the risk of the adhesive being damaged at high temperature and high humidity. The hardener may crosslink at least some of the carboxyl groups included in the adhesive.

[0048] The metal chelate hardener may include a coordination compound of a polyvalent metal. For example, the metal chelate hardener may include a coordination compound of a metal such as aluminum (Al), zirconium (Zr), and titanium (Ti). For example, the metal chelate hardener may include at least one of the following: an aluminum chelate-based hardener such as aluminum triethylacetoacetate, aluminum diisopropoxide ethylacetoacetate, aluminum acetylacetonate, and aluminum acetylacetonate; a titanium chelate-based hardener such as titanium isopropoxide, titanium ethylacetoacetate, titanium butylacetoacetate, and titanium acetylacetonate; and a zirconium chelate-based hardener such as zirconium 2-ethylhexanoate, zirconium acetylacetonate, and zirconium acetylacetonate. However, the present disclosure is not limited thereto. As long as the effects of the present disclosure are not impaired, the adhesive may include various types of metal chelate hardeners known in the art.

[0049] The metal chelate hardener may be included in an amount of 30 wt% to 60 wt% relative to the entire composition of the adhesive. The adhesive according to the present disclosure may include 30 wt% to 60 wt% of the metal chelate hardener. Accordingly, the reliability of the adhesive may be appropriately ensured at high temperature and high humidity, and the dissociability of the adhesive may be appropriately ensured.

[0050] When the metal chelate hardener is included in an amount less than 30 wt% relative to the entire composition of the adhesive, the adhesive may not be appropriately cured, and the reliability of the adhesive may be reduced at high temperature and high humidity. For example, when the metal chelate hardener is included in an amount less than 30 wt% relative to the entire composition of the adhesive, the adhesiveness of the adhesive may be reduced because the carboxyl groups in the resin binder are not appropriately crosslinked, and the durability of the adhesive may be reduced, such as changes in the physical properties of the adhesive at high temperature and high humidity.

[0051] When the metal chelate hardener is included in an amount greater than 60 wt% relative to the entire composition of the adhesive, the crosslinking ratio of the carboxyl groups in the resin binder may increase excessively, and the dissociability of the adhesive may decrease. For example, when the metal chelate hardener is included in an amount greater than 60 wt% relative to the entire composition of the adhesive, the carboxyl groups synthesized in the acrylic polymer may crosslink in an excessive amount, and the dissociability of the adhesive may decrease.

[0052] The epoxy-based hardener can be a bifunctional or more functional epoxy-based hardener (i.e., polyfunctional). For example, the epoxy-based hardener can include dialkylamine, tetramethylamine, polyolamine, amino alcohol, etc.

[0053] The epoxy-based hardener can be included in an amount of 0.5 wt% to 2 wt% relative to the entire composition of the adhesive. Alternatively, according to an embodiment, the epoxy-based hardener can be included in an amount of 0.5 wt% to 1.5 wt% relative to the entire composition of the adhesive. The adhesive according to the present disclosure can include 0.5 wt% to 2 wt% of the epoxy-based hardener. Therefore, the reliability of the adhesive can be appropriately ensured at high temperature and high humidity, and the dissociability of the adhesive can be appropriately ensured.

[0054] The isocyanate-based hardener can be a bifunctional or more functional isocyanate-based hardener (i.e., polyfunctional). For example, the isocyanate-based hardener can include xylene diisocyanate (“XDI”), including m-xylene diisocyanate, etc.; methylene bis(phenyl isocyanate) (“MDI”), including 4,4'-methylene bis(phenyl isocyanate), etc.; naphthalene diisocyanate; toluene diisocyanate; hexamethylene diisocyanate; and isophorone diisocyanate; and one or more of their adducts (e.g., in the form of isocyanurate).

[0055] The isocyanate-based hardener can be included in an amount of 0.5 wt% to 2 wt% relative to the entire composition of the adhesive. Alternatively, according to an embodiment, the isocyanate-based hardener can be included in an amount of 0.5 wt% to 1.5 wt% relative to the entire composition of the adhesive. The adhesive according to the present disclosure can include 0.5 wt% to 2 wt% of the isocyanate-based hardener. Therefore, the reliability of the adhesive can be appropriately ensured at high temperature and high humidity, and the dissociability of the adhesive can be appropriately ensured.

[0056] Then, the physical properties of the adhesives of each composition will be described below with reference to the experimental results.

[0057] Table 1 below shows the results of evaluating the adhesiveness (unit: grams-force per inch (gf / in)), dissociability, and reliability under high temperature and high humidity of adhesives, which are formed by changing the ratio of hardener to carboxylic acid with respect to the entire composition of the adhesive.

[0058] [Table 1]

[0059]

[0060] [Comparative Example 1]

[0061] Using 2-hydroxyethyl acrylate as a functional group, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate were reacted at a temperature of 60 °C to 80 °C for 8 hours to 10 hours to obtain an acrylic polymer having a weight-average molecular weight of 300,000 to 500,000, and further mixing an isocyanate-based hardener to prepare an adhesive. A metal chelate hardener was not used. To prepare the adhesive, 3.2 wt% of the isocyanate-based hardener was used with respect to the entire composition of the adhesive. As the isocyanate-based hardener, hexamethylene diisocyanate was used.

[0062] The adhesive of Comparative Example 1 does not contain carboxylic acid and does not contain a metal chelate hardener.

[0063] [Embodiment 1]

[0064] Compared with Comparative Example 1, an epoxy-based hardener was used instead of the isocyanate-based hardener, and further a carboxylic acid and a metal chelate hardener were used. Tetramethylamine was used as the epoxy-based hardener, and 1 wt% of the epoxy-based hardener was used with respect to the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid were mixed in equal amounts (wt%) such that 10 wt% of carboxylic acid was contained with respect to the entire composition of the adhesive. Aluminum acetylacetonate was used as the metal chelate hardener, and aluminum acetylacetonate was used in an amount of 50 wt% with respect to the entire composition of the adhesive.

[0065] [Embodiment 2]

[0066] An adhesive was prepared by including the same materials as in Embodiment 1 and mixing equal amounts (wt%) of acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid such that 15 wt% of carboxylic acid was contained with respect to the entire composition of the adhesive.

[0067] [Embodiment 3]

[0068] The adhesive is prepared by including the same materials as in Example 1 and mixing equal amounts (wt%) of acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid such that the entire composition of the adhesive contains 20 wt% of carboxylic acid.

[0069] <Example 4>

[0070] The adhesive is prepared by including the same materials as in Example 1 and mixing equal amounts (wt%) of acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid such that the entire composition of the adhesive contains 23 wt% of carboxylic acid.

[0071] <Example 5>

[0072] The adhesive is prepared by including the same materials as in Example 1 and mixing equal amounts (wt%) of acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid such that the entire composition of the adhesive contains 30 wt% of carboxylic acid.

[0073] In Comparative Example 1, Example 1, Example 2, Example 3, Example 4, and Example 5, the adhesive was coated on a film (here, the film is the adherend to which the adhesive is applied) to have a thickness of 5 micrometers (μm) to 20 μm.

[0074] As an experimental method for evaluating adhesiveness, an adhesiveness evaluation method according to the "ASTM D3330 Peel Adhesion of Pressure-Sensitive Adhesive Tapes" test method was used.

[0075] Referring to Table 1 above, it can be seen that the adhesiveness in Examples 1 to 5 is higher than that in Comparative Example 1. Compared with Comparative Example 1, Examples 1 to 5 may further contain a metal chelate hardener and may have higher adhesiveness.

[0076] In the dissociation evaluation, the experimental object was immersed in a 0.5 wt% aqueous sodium hydroxide solution, gently boiled at a temperature of 55 °C, and stirred at 1500 revolutions per minute (rpm) for 30 minutes. Referring to the dissociation evaluation in Table 1, the surface tackiness was evaluated according to the dissociation evaluation criteria of the eco-label certification standard EL103. If it did not meet the standard, it was recorded as "x", and if it met the standard, it was recorded as "o".

[0077] Referring to Table 1 above, it can be confirmed that Example 4 and Example 5 meet the ecological label certification standard EL103 dissociation evaluation criteria. The remaining examples do not meet the ecological label certification standard EL103 dissociation evaluation criteria. However, for the remaining examples, it is measured whether the adhesive remains on the film, and it is confirmed that a part of the adhesive has been removed from the film. Whether the adhesive remains on the film can be confirmed by measuring the weight of the film before and after immersion in an aqueous sodium hydroxide solution of 0.5 wt% and measuring whether the surface is sticky.

[0078] Reliability evaluation under high temperature and high humidity conditions is carried out at a temperature of 85 °C and a humidity of 85%. After the film is placed for 72 hours, it is measured whether any stains appear on the film. In this case, in Table 1, "ea" refers to the number of experimental objects evaluated, and "F" refers to the number of experimental objects in which stains appear. For example, "3F / 5ea" means that stains appear on 3 of the 5 protective films of the experimental objects.

[0079] Referring to the experimental results of Examples 1 to 4 in Table 1 above, it can be confirmed that Examples 1 to 4 have high reliability under high temperature and high humidity. Example 5 has lower reliability than Example 3 under high temperature and high humidity, but it can be confirmed that Example 5 has excellent dissociation according to the ecological label certification standard EL103 dissociation evaluation criteria.

[0080] Table 2 below shows the results of evaluating the adhesiveness, dissociability, and reliability under high temperature and high humidity of adhesives formed by changing whether a hardener is included and the ratio (wt%) of the hardener to the entire composition of the adhesive.

[0081] [Table 2]

[0082]

[0083]

[0084] <Comparative Example 2>

[0085] Using 2-hydroxyethyl acrylate as a functional group, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are reacted at a temperature of 60 °C to 80 °C for 8 hours to 10 hours to obtain an acrylic polymer having a weight average molecular weight of 300,000 to 500,000, and further a carboxylic acid and a first hardener are used to prepare an adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are used as the carboxylic acid. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%), such that the carboxylic acid is contained in an amount of 30 wt% with respect to the entire composition of the adhesive. The first hardener is a metal chelate hardener, and aluminum acetylacetonate is used, and aluminum acetylacetonate is used in an amount of 50 wt% with respect to the entire composition of the adhesive.

[0086] <Comparative Example 3>

[0087] Compared with Comparative Example 2, the same materials are included, but 23 wt% of the carboxylic acid is used with respect to the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%).

[0088] <Embodiment 6>

[0089] Compared with Comparative Example 3, the same materials are included, but a second hardener is further used. The second hardener is an isocyanate-based hardener, and hexamethylene diisocyanate is used, and hexamethylene diisocyanate is used in an amount of 0.5 wt% with respect to the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%).

[0090] <Embodiment 7>

[0091] Compared with Comparative Example 3, the same materials are included, but a second hardener is further used. The second hardener is an isocyanate-based hardener, and hexamethylene diisocyanate is used, and hexamethylene diisocyanate is used in an amount of 1.0 wt% with respect to the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%).

[0092] <Embodiment 8>

[0093] Compared with Comparative Example 3, the same materials are included, but a second hardener is further used. The second hardener is an epoxy-based hardener, and tetramethylammonium is used, and tetramethylammonium is used in an amount of 0.5 wt% with respect to the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%).

[0094] <Embodiment 9>

[0095] Compared with Comparative Example 3, the same materials are included, but a second hardener is further used. The second hardener is an epoxy-based hardener, and tetramethylamine is used, and tetramethylamine is used in an amount of 1.0 wt% based on the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%).

[0096] <Embodiment 10>

[0097] Compared with Comparative Example 3, the same materials are included, but a second hardener is further used. The second hardener is an epoxy-based hardener, and tetramethylamine is used, and tetramethylamine is used in an amount of 1.5 wt% based on the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%).

[0098] <Embodiment 11>

[0099] Compared with Comparative Example 3, the same materials are included, but a second hardener is further used. The second hardener is an epoxy-based hardener, and tetramethylamine is used, and tetramethylamine is used in an amount of 2.0 wt% based on the entire composition of the adhesive. Acrylic acid, propylene glycol monoacrylate, and β-acryloyloxypropionic acid are mixed in equal amounts (wt%).

[0100] The evaluation of adhesiveness, dissociability, and reliability at high temperature and high humidity was carried out in the same manner as the experimental method disclosed in Table 1.

[0101] First, observing the experimental results of Comparative Example 2, it can be confirmed that Comparative Example 2 has appropriate adhesiveness in the adhesiveness evaluation and meets the eco-label certification standard EL103 dissociability evaluation standard in the dissociability evaluation. However, Comparative Example 2 does not include a second hardener (isocyanate-based hardener or epoxy-based hardener), so it can be confirmed that stains appeared in all five experimental objects in the evaluation of reliability at high temperature and high humidity.

[0102] Observing the experimental results of Comparative Example 3, it can be confirmed that Comparative Example 3 has appropriate adhesiveness in the adhesiveness evaluation and meets the eco-label certification standard EL103 dissociability evaluation standard in the dissociability evaluation. However, Comparative Example 3 does not include a second hardener (isocyanate-based hardener or epoxy-based hardener), so it can be confirmed that stains appeared in three of the five experimental objects in the evaluation of reliability at high temperature and high humidity.

[0103] Comparing Example 6 with Comparative Example 3, it can be confirmed that the adhesiveness of the adhesive in Example 6 has increased. Since Example 6 includes an isocyanate-based hardener, the adhesive in Example 6 can be cured more firmly than the adhesive in Comparative Example 3, and the adhesiveness of the adhesive in Example 6 can increase.

[0104] Comparing Example 7 with Comparative Example 3, it can be confirmed that the adhesiveness of the adhesive in Example 7 has increased. Since Example 7 includes an isocyanate-based hardener, the adhesive in Example 7 can be cured more firmly than the adhesive in Comparative Example 3, and the adhesiveness of the adhesive in Example 7 can increase.

[0105] In addition, comparing Example 7 with Comparative Example 3, it can be confirmed that the reliability of the adhesive in Example 7 under high temperature and high humidity has increased.

[0106] Comparing Example 8 with Comparative Example 3, it can be confirmed that the adhesiveness of the adhesive in Example 8 has increased. Since Example 8 includes an epoxy-based hardener, the adhesive in Example 8 can be cured more firmly than the adhesive in Comparative Example 3, and the adhesiveness of the adhesive in Example 8 can increase.

[0107] In addition, comparing Example 8 with Comparative Example 3, it can be confirmed that the reliability of the adhesive in Example 8 under high temperature and high humidity has increased.

[0108] Comparing Example 9 with Comparative Example 3, it can be confirmed that the adhesiveness of the adhesive in Example 9 has increased. Since Example 9 includes an epoxy-based hardener, the adhesive in Example 9 can be cured more firmly than the adhesive in Comparative Example 3, and the adhesiveness of the adhesive in Example 9 can increase.

[0109] In addition, comparing Example 9 with Comparative Example 3, it can be confirmed that the reliability of the adhesive in Example 9 under high temperature and high humidity has increased. Observing the results of evaluating the reliability under high temperature and high humidity in Example 9, it can be confirmed that no stains appeared in all five test subjects.

[0110] Comparing Example 10 with Comparative Example 3, it can be confirmed that the reliability of the adhesive in Example 10 under high temperature and high humidity has increased. The adhesive in Example 10 has lower adhesiveness than the adhesive in Comparative Example 3, but observing the results of evaluating the reliability under high temperature and high humidity in Example 10, it can be confirmed that no stains appeared in all five test subjects.

[0111] Comparing Example 11 with Comparative Example 3, it can be confirmed that the reliability of the adhesive in Example 11 under high temperature and high humidity has increased. Observing the results of evaluating the reliability under high temperature and high humidity in Example 11, it can be confirmed that no stains have appeared in all five test subjects.

[0112] Example 11 does not meet the ecological label certification standard EL103 dissociation evaluation standard. However, it is measured whether the adhesive remains on the film, and it is confirmed that a part of the adhesive has been removed from the film.

[0113] Relative to the entire composition of the adhesive, the adhesive according to the present disclosure may contain 10 wt% to 30 wt% of carboxylic acid, and when reacting with water, at least a part of the adhesive may dissociate. In addition, relative to the entire composition of the adhesive, the adhesive according to the present disclosure may contain 30 wt% to 60 wt% of a metal chelate hardener and 0.5 wt% to 2 wt% of an epoxy-based hardener or an isocyanate-based hardener. Therefore, the reliability of the adhesive can be appropriately ensured under high temperature and high humidity, and the dissociability and adhesiveness of the adhesive can be appropriately ensured.

[0114] Hereinafter, with reference to Figure 1 , a protective film according to the present disclosure will be described. Figure 1 is a schematic cross-sectional view illustrating a protective film according to the present disclosure.

[0115] The protective film 1000 may include a substrate layer 10 and an adhesive layer 20.

[0116] The substrate layer 10 may contain an organic material. According to an embodiment, the substrate layer 10 may include at least one of polyethylene terephthalate, polyurethane, polyethylene, polyimide, polybutylene terephthalate, and polyethylene naphthalate. According to an embodiment, the substrate layer 10 may contain an ester-based polymer, a cycloolefin-based polymer (“COP”), a carbonate-based polymer, or a copolymer of these materials. However, the present disclosure is not limited thereto, and the substrate layer may contain various types of known organic materials.

[0117] The substrate layer 10 may have high transparency. In addition, the substrate layer 10 may have excellent mechanical strength and dimensional change after heat treatment.

[0118] The adhesive layer 20 may be provided on the substrate layer 10. The adhesive layer 20 may be provided on the substrate layer 10 based on the stacking direction DR.

[0119] The adhesive layer 20 may contain the adhesive described above. The adhesive layer 20 may be formed by applying (or coating) the adhesive described above.

[0120] When the substrate layer 10 includes an organic material (e.g., polyethylene terephthalate), if the adhesive does not have dissociability, it may be difficult to remove the adhesive layer 20 coated on the substrate layer 10. In order to recycle an organic material such as polyethylene terephthalate, the protective film 1000 must be shredded and provided to an extrusion molding machine, and provided in the form of pellets. In this case, if the adhesive layer 20 is not removed from the substrate layer 10, the protective films 1000 may become entangled with each other in the extrusion molding machine, making it difficult to provide the substrate layer 10 in the form of pellets.

[0121] According to the present disclosure, since the adhesive layer 20 of the protective film 1000 includes an adhesive having dissociability, the adhesive layer 20 can be easily removed from the substrate layer 10. In addition, since the substrate layer 10 of the protective film 1000 can be provided to an extrusion molding machine in the form of pellets, an organic material such as polyethylene terephthalate can be recycled.

[0122] According to an embodiment, the protective film 1000 may further include a release layer 30 disposed on the adhesive layer 20.

[0123] The release layer 30 can protect the adhesive layer 20. When the protective film 1000 is attached to a display device DD (see Figure 2 ), etc., the release layer 30 can be removed.

[0124] The release layer 30 may be composed of a substrate member and a layer disposed on the substrate member and coated with a release agent. The release agent may be an epoxy-based material, an epoxy-melamine-based material, an alkyd resin-based material, an acrylic-based material, a melamine-based material, a silicone-based, a fluorine-based material, a cellulose-based material, a urea resin-based material, a polyolefin-based material, or a paraffin-based material. However, the present disclosure is not limited thereto, and the release agent may be any release agent material available in the art.

[0125] Hereinafter, a display device DD on which the protective film 1000 according to the present disclosure is provided will be described with reference to Figure 2 . Figure 2 FIG. is a cross-sectional view schematically illustrating a display device DD provided with the protective film 1000 according to the present disclosure.

[0126] Referring to Figure 2 , the display device DD according to the present disclosure may include a display panel DP and a protective film 1000.

[0127] The display panel DP may be an organic light-emitting display panel, a liquid crystal display panel, a plasma display panel, an electrophoretic display panel, a microelectromechanical systems (“MEMS”) display panel, an electrowetting display panel, etc.

[0128] The protective film 1000 may be disposed on the display panel DP. When attached to the display panel DP, the release layer 30 of the protective film 1000 may be removed, and the adhesive layer 20 may come into contact with the display panel DP. However, the present disclosure is not limited thereto.

[0129] According to an embodiment, the display device DD may further include general components known in the art, such as a touch sensing unit and a polarization member, which are disposed between the display panel DP and the protective film 1000.

[0130] According to an embodiment of the present disclosure, an adhesive that can be more easily removed from a product and a protective film including the adhesive may be provided, and the protective film may be recycled.

[0131] As described above, the best embodiments of the present disclosure have been disclosed through the detailed description and the drawings. However, those skilled in the art or those of ordinary skill in the art will understand that various modifications and changes are possible without departing from the gist and scope of the present disclosure as set forth in the appended claims.

[0132] Therefore, the technical protection scope of the present disclosure is not limited to the detailed description described in the specification, but should be determined by the appended claims.

Claims

1. Adhesive, comprising: a resin binder comprising an acrylic polymer and a carboxylic acid; Metal chelate hardeners; and Epoxy based hardener. 2 . The adhesive according to claim 1 , wherein the carboxylic acid is contained in an amount of 10 wt % to 30 wt % with respect to the entire composition of the adhesive. 3 . The adhesive according to claim 1 , wherein the carboxylic acid is contained in an amount of greater than 20 wt % and equal to or less than 30 wt % with respect to the entire composition of the adhesive.

4. The adhesive according to claim 1, wherein the carboxylic acid reacts with the acrylic polymer and at least one carboxyl group of the carboxylic acid is synthesized into the acrylic polymer, wherein the carboxylic acid comprises acrylic acid, propylene glycol monoacrylate and β-acryloxypropionic acid, wherein the metal chelate hardener comprises at least one of an aluminum chelate-based hardener, a titanium chelate-based hardener, and a zirconium chelate-based hardener, wherein the aluminum chelate-based hardener comprises at least one of aluminum triacetoacetate, aluminum acetoacetate diisopropoxide, aluminum triacetylacetonate, and aluminum acetylacetonate, The titanium chelate-based hardener includes at least one of titanium isopropoxide, titanium ethyl acetoacetate, titanium butyl acetoacetate, and titanium acetylacetonate, and The zirconium chelate-based hardener includes at least one of zirconium 2-ethylhexanoate, zirconium acetoacetate, and zirconium acetylacetonate. 5 . The adhesive according to claim 1 , wherein the metal chelate hardener is included in an amount of 30 wt % to 60 wt % with respect to the entire composition of the adhesive. 6 . The adhesive according to claim 1 , wherein the epoxy-based hardener is included in an amount of 0.5 wt % to 2 wt % with respect to the entire composition of the adhesive.

7. The adhesive of claim 1, wherein the epoxy-based hardener is a multifunctional epoxy-based hardener. 8 . The adhesive according to claim 1 , wherein the resin binder has a weight average molecular weight of 8,000 to 150,000.

9. Adhesives, including: a resin binder comprising an acrylic polymer and a carboxylic acid; Metal chelate hardeners; and Isocyanate based hardeners, The carboxylic acid is included in an amount of 10 wt % to 30 wt % relative to the entire composition of the adhesive.

10. The adhesive according to claim 9, wherein the isocyanate-based hardener is contained in an amount of 0.5 wt % to 2 wt % relative to the entire composition of the adhesive, wherein the isocyanate-based hardener is a multifunctional isocyanate-based hardener, and The metal chelate hardener is included in an amount of 30 wt % to 60 wt % relative to the entire composition of the adhesive.

11. Protective film, including: Base layer; as well as The adhesive according to any one of claims 1 to 10 on the substrate layer.

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