Adhesive film having excellent re-peeling property and workability

Abstract

The present invention relates to an adhesive composition comprising a polyurethane resin composition including a polyurethane-based resin as a main component, an interfacial modifier, and an adhesion enhancer, the weight ratio (a / b) of the interfacial modifier (a) and the adhesion enhancer (b) being 0.8 or less.

Description

Technical Field

[0001] This invention relates to an adhesive composition having excellent re-peelability and workability, and a transparent adhesive film using the same. Background Technology

[0002] With the development of the information society, the demand for display devices has grown in various forms. Recently, in response, various display devices such as Liquid Crystal Display Devices (LCDs), Plasma Display Panels (PDPs), Electroluminescent Displays (ELDs), Vacuum Fluorescent Displays (VFDs), Organic Light Emitting Diodes (OLEDs), and Light Emitting Diodes (LEDs) have been researched and are being used. Furthermore, recent display devices are being installed both indoors and outdoors for purposes such as advertising. In particular, transparent LED displays can clearly show objects behind products when power is off, and can display various content like digital signage when the LEDs are on.

[0003] In a transparent LED display, a transparent LED film is a display device in which light-emitting diodes (hereinafter referred to as LEDs) are disposed on the film as a light source. A transparent LED film display may include multiple LEDs, and the intended image can be displayed by operating the LEDs according to a drive signal transmitted from the outside. Since such a transparent LED film display is formed entirely of a thin film, it can have a thin, lightweight, and flexible structure.

[0004] Transparent LED film displays can be attached to mounts with various surfaces, such as curved or flat surfaces, for various purposes. In order to attach such transparent LED film displays to various surfaces, an adhesive with excellent workability and adhesion reliability is required, namely, a transparent adhesive film.

[0005] The aforementioned transparent adhesive film is attached to one side of the transparent LED film display, and the other side of the transparent adhesive film is attached to the surface of the target mounting object, thereby fixing the transparent LED film display to the mounting object. If the transparent LED film display is incorrectly positioned during the attachment process, or if foreign matter gets mixed between it and the mounting object, or if the transparent LED film display needs to be permanently removed, the transparent adhesive film needs to be peeled off from the mounting object again. Therefore, if there are the requirements as described above, the transparent adhesive film should be easy to peel off from the surface of various mounting objects without leaving any residue, and should not damage the transparent LED film display during peeling. On the other hand, when the transparent LED film is completely attached to the mounting object, the adhesion must remain reliable, and there should be no appearance defects such as lifting or peeling on the mounting object over time. Furthermore, when the transparent LED film display is removed after use, there should be no contamination or damage on the attachment surface of the mounting object.

[0006] As mentioned above, in addition to excellent optical performance, appearance and adhesion reliability, transparent LED thin film displays also require "re-peelability". However, although existing adhesive technologies can achieve re-peelability, adhesion reliability and wetting properties for glass surface mounts to a certain extent, they still cannot meet sufficient re-peelability, adhesion reliability and wetting properties for mounts with plastic or glass surfaces. Summary of the Invention

[0007] Technical issues

[0008] To address the aforementioned problems, the present invention aims to provide an adhesive composition and a transparent adhesive film using the same, which exhibit superior re-peelability and workability on plastic or glass surfaces, unlike existing adhesive compositions.

[0009] More specifically, the present invention aims to provide an adhesive composition that exhibits excellent re-peelability due to low adhesive force after being applied to the surface of an adherend, but has excellent adhesive reliability due to the gradual increase in adhesive force over time.

[0010] Furthermore, the present invention aims to provide an adhesive composition that maintains adequate adhesive strength even as the adhesive strength increases over time, so that in certain situations where peeling is required, re-peeling can be performed without damage to the adhered material and adhesive residue.

[0011] Furthermore, the present invention aims to provide an adhesive composition that allows for adhesion without defects such as bubbles due to its excellent wettability.

[0012] Solution to the problem

[0013] The present invention provides an adhesive film comprising a base film, an adhesive layer on the base film, and a release film on the back side of the adhesive layer. The adhesive layer is made of an adhesive composition comprising a polyurethane resin composition containing a polyurethane resin as a main component, an interface modifier, and an adhesive reinforcing agent. The weight ratio (a / b) of the interface modifier (a) and the adhesive reinforcing agent (b) in the adhesive composition is 0.8 or less.

[0014] In one embodiment of the present invention, the value of A in the adhesive layer according to the following formula 1 can be 1 or more.

[0015] [Formula 1]

[0016] A = (A2 - A1) / A1

[0017] A1: Adhesion strength (gf / inch) after being applied to the surface of the substrate and left at room temperature for 30 minutes.

[0018] A2: Adhesive strength (gf / inch) after being applied to the surface of the substrate and left at room temperature for 1000 hours.

[0019] In one embodiment of the present invention, the above-mentioned A1 value can be below 50 gf / inch.

[0020] In one embodiment of the present invention, the interface modifier may be an organosilicon-based nonionic interface modifier.

[0021] In one embodiment of the present invention, the hydrophilic-lipophilic balance (HLB) value of the above-mentioned organosilicon nonionic interface modifier can be 4 to 8.

[0022] In one embodiment of the present invention, the above-mentioned organosilicon nonionic interface modifier may be polyalkyleneoxide modified dimethylpolysiloxane.

[0023] In one embodiment of the present invention, the adhesive reinforcing agent may be a silane coupling agent.

[0024] In one embodiment of the present invention, the surface of the adherend can be more hydrophilic than the release film.

[0025] In one embodiment of the present invention, the surface of the object to be adhered to may be transparent plastic or glass.

[0026] Invention Effects

[0027] The adhesive composition according to the present invention exhibits excellent wetting properties, re-peelability, and adhesive reliability. Specifically, it can be applied without defects such as bubbles, and can be re-peeled onto surfaces such as plastics or glass. It has excellent peel strength and workability, and can prevent peeling, lifting, etc. after complete application. Detailed Implementation

[0028] The invention described below is designed to solve the above problems.

[0029] An embodiment of the present invention provides an adhesive film comprising a base film, an adhesive layer on the base film, and a release film on the back side of the adhesive layer. The adhesive layer is made of an adhesive composition comprising a polyurethane resin composition containing a polyurethane resin as a main component, an interface modifier, and an adhesive reinforcing agent. The weight ratio (a / b) of the interface modifier (a) and the adhesive reinforcing agent (b) in the adhesive composition is 0.8 or less.

[0030] When the adhesive film according to the present invention is applied to the surface of the adherend, the interface modifier in the adhesive layer is distributed on the surface of the adherend, so its adhesion to the surface of the adherend is low. However, as time goes by, the interface modifier rearranges and the adhesion to the surface of the adherend is improved by the adhesive enhancer. Thus, the adhesive composition of the present invention has excellent wettability, re-peelability and adhesive reliability.

[0031] In one embodiment of the present invention, the adhesive layer of the adhesive film satisfies an A value of 1 or more for the surface of the adherend according to the following formula 1, thereby increasing the adhesive force when placed at room temperature after application, and thus having excellent adhesive reliability.

[0032] [Formula 1]

[0033] A = (A2 - A1) / A1

[0034] A1: Adhesion strength (gf / inch) after being applied to the surface of the substrate and left at room temperature for 30 minutes.

[0035] A2: Adhesive strength (gf / inch) after being applied to the surface of the substrate and left at room temperature for 1000 hours.

[0036] In one embodiment of the present invention, the A1 value of the adhesive film can be less than 50 gf / inch.

[0037] The release film present on one side of the adhesive film of the present invention is hydrophobic to provide release properties for the adhesive layer. However, the surface of the adherend, such as plastic or glass, is more hydrophilic than the release film. Therefore, when the release film on the adhesive layer is removed and the adhesive layer is attached to the surface of the adherend, the hydrophobic groups of the interface modifier present in the adhesive layer immediately after attachment orient to the surface of the adherend, resulting in low adhesive strength. However, over time, for the surface of the adherend, such as plastic or glass, which is relatively more hydrophilic than the release film, the hydrophobic and hydrophilic groups of the interface modifier reach equilibrium and rearrange, causing the adhesive enhancer to react with the surface of the adherend to improve the adhesive strength.

[0038] Examples of the aforementioned plastics include, but are not limited to, transparent plastics such as polymethyl methacrylate (PMMA), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA), polypropylene (PP), polyethylene (PE), and polyvinyl chloride (PVC).

[0039] The adhesive layer of the present invention, by simultaneously including the aforementioned interface modifier and adhesive enhancer, simultaneously satisfies the effects of re-peelability and adhesive stability on the surfaces of adhered objects such as plastics or glass. The adhesive layer containing the adhesive composition of the present invention exhibits excellent re-peelability immediately after being applied to the surface of the adhered object due to the presence of the interface modifier on the surface of the adhesive layer. However, over time, the interface modifier and adhesive enhancer rearrange, thereby increasing the adhesive force through the interaction between the adhesive enhancer and the surface of the adhered object, thus imparting adhesive stability.

[0040] The invention will be described in more detail below.

[0041] <Polyurethane Resin Composition>

[0042] The above-mentioned polyurethane resin composition includes polyurethane resin as the main component, which is obtained by curing a polyurethane prepolymer formed by reacting a polyol with a polyfunctional isocyanate compound in the presence of a catalyst.

[0043] The aforementioned polyols may contain one type of polyol, more preferably two or more types. Among the two or more polyols, one may be a polyol containing three or more OH groups, examples of which are selected from the group consisting of polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols. Due to the aforementioned polyol composition, excellent reworkability and other properties can be exhibited.

[0044] The aforementioned polyester polyols can be obtained through an esterification reaction between the polyol component and the acid component. Examples of polyol components can be selected from the group consisting of ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerol, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol. Examples of acidic components include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanoic acid, 1,14-tetradecanoic acid, dimer acids, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, and their anhydrides.

[0045] Furthermore, the aforementioned polyether polyols can be prepared by addition polymerization of alkylene oxides selected from ethylene oxide, propylene oxide, and butylene oxide using water, low molecular weight polyols (propylene glycol, ethylene glycol, glycerol, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), and dihydroxybenzenes (catechol, resorcinol, hydroquinone, etc.) as initiators. Specific examples include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0046] The aforementioned polycaprolactone polyol is a caprolactone-based polyester diol obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone or σ-valerolactone. Examples include: polycarbonate polyols obtained by polycondensation of the aforementioned polyol components with phosgene; polycarbonate polyols obtained by transesterification and condensation reactions of the aforementioned polyol components with carbonate diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, or dibenzyl carbonate; polycarbonate polyols copolymerized from two or more of the aforementioned polyol components; and polycarbonate polyols obtained by esterification reactions of the aforementioned various polycarbonate polyols with carboxyl-containing compounds. Polycarbonate polyols; polycarbonate polyols obtained by etherification reactions of the above-mentioned polycarbonate polyols with hydroxyl-containing compounds; polycarbonate polyols obtained by transesterification reactions of the above-mentioned polycarbonate polyols with ester compounds; polycarbonate polyols obtained by transesterification reactions of the above-mentioned polycarbonate polyols with hydroxyl-containing compounds; polyester polycarbonate polyols obtained by polycondensation reactions of the above-mentioned polycarbonate polyols with dicarboxylic acid compounds; and polyether polycarbonate polyols obtained by copolymerization reactions of the above-mentioned polycarbonate polyols with epoxy alkane.

[0047] The castor oil-based polyols mentioned above are obtained by reacting castor oil fatty acids with the aforementioned polyol components.

[0048] As another component used in the preparation of polyurethane resins, polyfunctional isocyanate compounds can be used alone or in combination, including polyfunctional aliphatic isocyanate compounds, polyfunctional alicyclic isocyanate compounds, polyfunctional aromatic diisocyanate compounds, and trimers having isocyanurate rings.

[0049] Preferred examples of the above-mentioned multifunctional aliphatic isocyanate compounds may be selected from the group consisting of trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propene diisocyanate, 1,3-butene diisocyanate, dodecamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.

[0050] Furthermore, examples of the aforementioned polyfunctional alicyclic isocyanate compounds include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated phenyl dimethyl diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated tetramethylxylene diisocyanate. The aforementioned polyfunctional aromatic diisocyanate compounds may be selected from the group consisting of phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, and phenyl dimethyl diisocyanate.

[0051] Polyurethane prepolymers with hydroxyl terminals can be prepared by reacting the above-mentioned polyols with polyfunctional isocyanate compounds in the presence of a catalyst, and then a three-dimensional network structure can be formed by using a polyfunctional isocyanate with two or more functional groups as a curing agent.

[0052] As other examples of the above-mentioned polyfunctional isocyanate compounds, trimethylolpropane adducts of the various polyfunctional isocyanate compounds described above, biuret obtained by reacting with water, and trimers having isocyanurate rings can be used, or they can be used in combination.

[0053] As described above, polyurethane resin is obtained by curing a composition comprising polyols and polyfunctional isocyanate compounds. The composition may include, without impairing the effects of the present invention, antistatic agents, catalysts, other resin components besides polyurethane resin, tackifiers, inorganic fillers, organic fillers, metal powders, pigments, softeners, plasticizers, anti-aging agents, conductive agents, antioxidants, ultraviolet absorbers, light stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, lubricants, solvents, etc. More preferably, it may include anti-deterioration agents such as antistatic agents, antioxidants, ultraviolet absorbers, or light stabilizers.

[0054] <Interface modifier>

[0055] An interface modifier is a compound that possesses both hydrophilicity (soluble in water) and hydrophobicity (soluble in oil) within a single molecule. Hydrophilicity refers to the property of readily binding with water molecules. Conversely, a property exhibiting a weak affinity for water is called hydrophobicity.

[0056] In this invention, an organosilicon-based nonionic interface modifier can be used as the aforementioned interface modifier.

[0057] The aforementioned organosilicon nonionic interface modifiers can be selected from modified polydimethylsiloxane (e.g., alkyl-modified, phenyl-modified, amino-modified, polyether-modified, polyoxyethylene-modified polydimethylsiloxane, etc.), organosilicon, polyalkylene-modified heptamethyl trisiloxane, polyalkylene oxide-modified dimethylpolysiloxane, polyalkylene oxide-modified heptamethyl trisiloxane, polyalkylene oxide-modified heptamethylsiloxane, polyalkylene oxide-modified heptamethylsiloxane, polyether polymethylsiloxane-copolymer, and polyethoxlated dimethylsiloxane. The agent is selected from, but is not limited to, one or more of the group consisting of siloxanes, polymethylsiloxane copolymers, polyoxpropylene-polyoxyethylene block copolymers, and silicone polyether copolymers. In a preferred embodiment, the aforementioned silicone nonionic interface modifier can be a polyoxyalkylene-modified silicone having a structure in which polyoxyethylene / polyoxypropylene polar blocks are grafted onto a silicone backbone. This can be polyoxyethylene-modified dimethylpolysiloxane or polyoxypropylene-modified dimethylpolysiloxane. Furthermore, a polyoxyalkylene-modified silicone containing the aforementioned polyoxyethylene and polyoxypropylene is preferred, in which case the ends of the polyoxyethylene and polyoxypropylene can be capped with alkyl groups such as methyl or butyl. When the ends of polyethylene oxide and polypropylene oxide are not alkyl-terminated, the hydroxyl groups generated through the reaction can chemically react with the polyurethane resin of the adhesive, thereby hindering the rearrangement of the interface modifiers on the surface of the adhered objects.

[0058] Based on 100 parts by weight of polyurethane resin, the amount of the aforementioned silicone nonionic interface modifier is preferably 0.01 parts by weight to 5 parts by weight. If the content of the aforementioned silicone nonionic interface modifier is less than 0.01 parts by weight, the adhesive force will increase due to insufficient interface modifier dosage at the adhesive interface in contact with the release film, resulting in problems with reworkability. If the content of the aforementioned silicone nonionic interface modifier is greater than 5 parts by weight, the equilibrium rearrangement will take a long time due to excessive interface modifier dosage at the adhesive interface, making it impossible to increase the adhesive force, resulting in poor adhesive reliability.

[0059] The hydrophilic-lipophilic balance (HLB) value of the aforementioned silicone-based nonionic interface modifiers can be between 4 and 8. It was found that when the HLB value of the aforementioned silicone-based nonionic interface modifiers is between 4 and 8, after the adhesive is applied to the surface of the adherend, the hydrophilic groups of the interface modifier orient towards the surface of the adherend over time, thus gradually increasing the adhesive strength. On the other hand, if the HLB value is less than 4, it is close to hydrophobic (lipophilic), therefore no rearrangement occurs towards the surface of the adherend in the adhesive, making it difficult to improve the adhesive strength. If the HLB value is greater than 8, it is close to hydrophilic, no rearrangement occurs in the adhesive, the adhesive strength does not increase, and therefore the adhesive reliability is poor.

[0060] <Adhesive Strengthening Agent>

[0061] In this invention, a silane coupling agent can be used as the aforementioned adhesive reinforcing agent. In one embodiment, vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, etc., can be used as the aforementioned adhesive reinforcing agent.

[0062] Based on 100 parts by weight of polyurethane resin, the amount of the above-mentioned adhesive reinforcing agent is preferably from 0.1 parts by weight to 10 parts by weight. If the content of the above-mentioned adhesive reinforcing agent is less than 0.1 parts by weight, the adhesive force will not increase after being applied to the bonded surface, and the bonding reliability will be poor. If the content of the above-mentioned adhesive reinforcing agent is greater than 10 parts by weight, when peeling is required after a certain period of time, there will be problems with the bonded object being damaged and adhesive residue occurring.

[0063] In one embodiment of the present invention, the weight ratio (a / b) of the interface modifier (a) and the adhesive reinforcing agent (b) in the adhesive composition is 0.8 or less. Preferably, the weight ratio (a / b) of the interface modifier (a) and the adhesive reinforcing agent (b) is 0.7 or less, more preferably 0.5 or less. When the weight ratio (a / b) of the interface modifier (a) and the adhesive reinforcing agent (b) is greater than 0.8, the adhesive force does not increase over time, resulting in very low adhesive reliability.

[0064] In the following description, the structure and function of the present invention will be described in more detail through preferred embodiments. However, the following embodiments are merely examples to aid in understanding the present invention, and the scope of the invention is not limited thereto.

[0065] Example 1: Method for preparing adhesive film

[0066] Example 1

[0067] Six parts by weight of a multifunctional hexamethylene diisocyanate crosslinking agent were mixed with 100 parts by weight of a hydroxyl-terminated polyurethane prepolymer (weight average molecular weight of 80,000), and 0.01 parts by weight of dibutyltin dilaurate (DBTDL) as a catalyst, 0.3 parts by weight of polypropylene oxide / ethylene oxide (20 / 80) polydimethylsiloxane with an HBL of 7 and 2 parts by weight of 3-methacryloylpropyltrimethoxysilane were added. The mixture was diluted with methyl ethyl ketone (MEK) to achieve a solid content of 50% by weight, and then mixed and defoamed to prepare an adhesive composition.

[0068] The prepared adhesive composition was coated onto a PET base film and dried in an oven at 120°C for 3 minutes to achieve an adhesive layer thickness of 100 μm. Then, a PET release film was laminated to protect the coated adhesive surface and cured at 50°C for 2 days to form a cross-linked structure, thereby preparing an adhesive film.

[0069] Example 2 and Comparative Examples 1 to 4

[0070] Except for the changes in the composition of the adhesive composition as shown in Table 1 below, the adhesive film was prepared in the same manner as in Example 1.

[0071] Table 1 below shows the composition and component ratios of the examples and comparative examples.

[0072] Table 1

[0073]

[0074] Experimental Example: Evaluation of Adhesive Film Properties

[0075] 1. Adhesion evaluation

[0076] Samples were prepared by cutting the adhesive films prepared in the examples and comparative examples into pieces with a horizontal length of 25 mm and a vertical length of 200 mm. The adhesive layers of the samples were then attached to polymethyl methacrylate (PMMA) and polycarbonate (PC) sheets using a 2 kg roller. For sample A1, which was left at room temperature for 30 minutes, and sample A2, which was left at room temperature for 1000 hours, the adhesive force was measured using a tensile testing machine at a peel speed of 5 mm / s and a peel angle of 180 degrees. The results confirmed that the A value was greater than 1 in all cases, and the average value of the measured values ​​is recorded in Table 1.

[0077] A = (A2 - A1) / A1

[0078] A1: Adhesion strength (gf / inch) after being applied to the surface of the substrate and left at room temperature for 30 minutes.

[0079] A2: Adhesive strength (gf / inch) after being applied to the surface of the substrate and left at room temperature for 1000 hours.

[0080] Table 2

[0081]

[0082] 2. Reworkability Evaluation

[0083] Samples were prepared by cutting the adhesive films prepared in the above examples and comparative examples into pieces with a horizontal length of 500 mm and a vertical length of 600 mm. The adhesive layers of the samples were then applied to polymethyl methacrylate (PMMA), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyamide (PA), and glass plates using a roller. After application, the adhesive films were left at room temperature for 30 minutes, then peeled off and reapplied. Reworkability was evaluated according to the following criteria.

[0084] <Evaluation Criteria>

[0085] ○: During peeling, it does not damage the substrate and leaves no adhesive residue. It can be reattached without producing air bubbles.

[0086] ×: Damage to the substrate or residual adhesive may occur during peeling.

[0087] 3. Adhesion reliability evaluation

[0088] Samples were prepared by cutting the adhesive films prepared in the above examples and comparative examples into pieces with a horizontal length of 500 mm and a vertical length of 600 mm. The adhesive layer of the above samples was then attached to a curved PMMA board. After attachment, the appearance was observed at room temperature for up to 1000 hours. The adhesion reliability was evaluated according to the following evaluation criteria.

[0089] <Evaluation Criteria>

[0090] ○: No peeling, lifting, or bubbles; excellent adhesion.

[0091] ×: Peeling, lifting, or bubbling occurs.

[0092] Table 3

[0093]

[0094] As described in Table 3 above, the embodiments do not cause damage to the substrate during peeling, and there is no adhesive residue. Therefore, they have excellent reworkability. No lifting or peeling of the adhered surface was observed over time, which shows that the adhesion reliability is excellent.

[0095] On the other hand, in the cases of Comparative Examples 1 to 4, neither reworkability nor adhesive reliability was simultaneously satisfied. Therefore, according to the present invention, it is significant that the adhesive force is initially low after being attached to the surface of the substrate, thus exhibiting excellent re-peelability, while the adhesive force gradually increases over time, providing excellent adhesive reliability.

Claims

1. An adhesive film comprising a base film, an adhesive layer on the base film, and a release film on the back side of the adhesive layer, characterized in that, The aforementioned adhesive layer is made of an adhesive composition comprising a polyurethane resin composition containing a polyurethane resin as the main component, an organosilicon nonionic interface modifier, and an adhesive reinforcing agent. Among them, the hydrophilic-lipophilic balance value of the above-mentioned organosilicon nonionic interface modifiers is 4 to 8, and The weight ratio of the aforementioned silicone nonionic interface modifier a and the aforementioned adhesive reinforcing agent b in the adhesive composition is 0.8 or less.

2. The adhesive film according to claim 1, characterized in that, The A value of the above adhesive layer is 1 or more according to the following formula 1: [Formula 1] A = (A2 - A1) / A1 A1: Adhesion strength after being applied to the surface of the object and left at room temperature for 30 minutes; A2: Adhesion strength after being applied to the surface of the object and left at room temperature for 1000 hours.

3. The adhesive film according to claim 2, characterized in that, The A1 value mentioned above is below 50 gf / inch.

4. The adhesive film according to claim 1, characterized in that, The aforementioned organosilicon nonionic interface modifier is a polyepoxide-modified dimethylpolysiloxane.

5. The adhesive film according to claim 1, characterized in that, The aforementioned adhesive reinforcing agent is a silane coupling agent.

6. The adhesive film according to claim 1, characterized in that, The surface of the object being adhered to is more hydrophilic than the release film.

7. The adhesive film according to claim 6, characterized in that, The surface of the object to be adhered to is transparent plastic or glass.

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