Adhesive film for surface protection and optical member including the same

Abstract

The present invention relates to an adhesive film for surface protection and an optical member including the same. The adhesive film for surface protection is formed from a composition for an adhesive film, the composition for an adhesive film including a curable component containing a urethane-based adhesive, a curing agent, and a plasticizer, and having a peel strength change rate of -50% to 20% calculated by Equation 1.

Description

[0001] Citation of Related Applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2021-0127197, filed with the Korean Intellectual Property Office on September 27, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to an adhesive film for surface protection and an optical member including the adhesive film. Background Art

[0004] In order to prevent defects from occurring on the surfaces of optical members or electronic members such as LCDs, organic EL displays, touch panels using them, lens units of cameras, electronic devices, etc., during processes such as processing, assembly, inspection, transportation, etc., a surface protection film is attached to the exposed surfaces of the optical members or electronic members. When surface protection is not required, the surface protection film is removed from the optical member or electronic member. In recent years, after the manufacturing process of an optical member or an electronic member, a single surface protection film has been continuously used through assembly, inspection, transportation, etc. until final shipment.

[0005] Surface protection films prepared using (meth)acrylic resins in the adhesive layer are known in the art. However, since such surface protection films exhibit poor wettability with respect to optical members or electronic members, air bubbles are trapped between the members and the surface protection films. In addition, residues of the adhesive layer remain when the surface protection film is separated from the member. Therefore, typical surface protection films are not suitable for surface protection of members, especially for the surfaces of members that are easily damaged by foreign substances.

[0006] In recent years, surface protection films using urethane-based adhesives in the adhesive layer have been reported in the art. However, typical urethane-based adhesives exhibit poor initial wettability with respect to optical or electronic members, thus easily introducing air bubbles into them. In addition, typical urethane-based adhesives significantly increase adhesiveness over time. With the significant increase in the adhesiveness of the protective film over time, it becomes difficult to remove the protective film from the optical or electronic member. Surface protection films using typical urethane-based adhesives in the adhesive layer present a problem of deteriorated reprocessability due to an increase in peel strength when attached to an optical or electronic member for a long time.

[0007] The background art of the present invention is disclosed in Korean Patent Publication No. 10-2012-0050136, etc. Summary of the Invention

[0008] One aspect of the present invention is to provide an adhesive film for surface protection that exhibits low variation in peel strength even after being left under high temperature / humidity conditions for a long period of time.

[0009] Another aspect of the present invention is to provide an adhesive film for surface protection having a good appearance even after being left under high temperature / humidity conditions for a long time.

[0010] Another aspect of the present invention is to provide an adhesive film for surface protection, which can be attached to an adherend to protect the adherend, does not deform and / or damage the adherend even after being left under high temperature / humidity conditions for a long time, and can be easily removed therefrom.

[0011] One aspect of the present invention relates to an adhesive film for surface protection.

[0012] 1. An adhesive film for surface protection, formed from a composition for an adhesive film, the composition for an adhesive film comprising a curable component containing a urethane-based adhesive, a curing agent, and a plasticizer, and the adhesive film having a peel strength variation rate of -50% to 20% calculated by Equation 1:

[0013] [Equation 1]

[0014] Peel strength change rate = [(P2–P1) / P1] x 100

[0015] Wherein, P1 is the initial peel strength of the adhesive film relative to the alkali-free glass plate (unit: gf / inch), and

[0016] P2 is the peel strength (unit: gf / inch) of the adhesive film with respect to the non-alkali glass plate after being left at 85° C. and 85% RH (relative humidity) for 10 days.

[0017] 2. In 1, the adhesive film may have a P1 value of 4 gf / inch or less and a P2 value of 4 gf / inch or less.

[0018] 3. In 1 to 2, the plasticizer may be present in an amount of 5 to 20 parts by weight relative to 100 parts by weight of the curable component.

[0019] 4. In 1 to 3, the plasticizer may include a 18 Monoprotic or polyprotic acid with C3-C 18 Esters of branched alcohols, C 14 -C 18 Esters of unsaturated fatty acids or branched-chain acids with tetravalent or lower alcohols, C6-C 10 At least one of esters of monobasic acid or polybasic acid and polyalkylene glycol.

[0020] 5. Among 1 to 4, the plasticizer can be an ester compound having one or more ester groups represented by Formula 1:

[0021] [Formula 1]

[0022] *-C(=O)-O-X-CH(CH3)2,

[0023] where * is the bonding site of the element and X is a single bond or a divalent organic group.

[0024] 6. Among 1 to 5, the plasticizer can include at least one selected from isopropyl myristate, isopropyl palmitate, isotridecyl isononanoate, diisononyl 1,2-cyclohexanedicarboxylate, isostearyl palmitate, isostearyl laurate, diisostearyl adipate, and diisocetyl sebacate.

[0025] 7. Among 1 to 6, the urethane-based binder can be a hyperbranched binder.

[0026] 8. Among 1 to 7, the urethane-based binder can include at least one unit selected from units derived from polyether polyols and polyester polyols.

[0027] 9. Among 1 to 8, the urethane-based binder can be formed from at least one polyisocyanate compound and a polyol, the polyol containing 50 wt% to 95 wt% polyether triol and 5 wt% to 50 wt% polyether diol.

[0028] 10. In 9, the polyether diol can have a number average molecular weight of 400 to 10,000, and the polyether triol can have a number average molecular weight of 400 to 10,000.

[0029] 11. Among 1 to 10, the urethane-based binder can be formed from at least one polyisocyanate compound and a polyol, the polyol containing 50 wt% to 90 wt% polyether triol, 5 wt% to 40 wt% polyether diol, and 5 wt% to 40 wt% polyester diol.

[0030] 12. Among 1 to 11, the polyether diol can have a number average molecular weight of 400 to 10,000, the polyether triol can have a number average molecular weight of 400 to 10,000, and the polyester diol can have a number average molecular weight of 1,000 to 5,000.

[0031] 13. Among 1 to 12, the curable component can further contain a polyol.

[0032] 14. Among 1 to 13, relative to 100 parts by weight of the urethane-based binder, the polyol can be present in an amount greater than 0 to 70 parts by weight.

[0033] 15. Among 1 to 14, the polyol may include at least one selected from polyether - based polyols, polyester - based polyols, polycaprolactone - based polyols, and polycarbonate - based polyols.

[0034] 16. Among 1 to 15, the curing agent may include an isocyanate - based curing agent and may be present in an amount of 1 to 10 parts by weight relative to 100 parts by weight of the curable components.

[0035] 17. Among 1 to 16, the curing agent may include an isocyanate - based curing agent of isocyanurates.

[0036] 18. Among 1 to 17, the adhesive film may further include at least one selected from cross - linking catalysts, leveling agents, antistatic agents, antioxidants, and retarders.

[0037] Another aspect of the present invention relates to an optical member including an optical film and an adhesive film for surface protection according to the present invention on at least one surface of the optical film.

[0038] The present invention provides an adhesive film for surface protection which exhibits a low change in peel strength even after being placed for a long time under high - temperature / humidity conditions.

[0039] The present invention provides an adhesive film for surface protection which has a good appearance even after being placed for a long time under high - temperature / humidity conditions.

[0040] The present invention provides an adhesive film for surface protection which can be attached to an adherend to protect the adherend and which, even after being placed for a long time under high - temperature / humidity conditions, does not deform and / or damage the adherend and can be easily removed therefrom. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a cross - sectional view of a specimen for measuring modulus of the adhesive film for surface protection in the examples. DETAILED DESCRIPTION

[0042] Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited to the following embodiments and can be implemented in different ways. The following embodiments are provided for those skilled in the art to thoroughly understand the present invention.

[0043] Herein, the "adherend" may include a glass plate, a plastic film, or a panel for a display device, but is not limited thereto. The "adherend" may represent the outermost surface of an optical member or an electronic member.

[0044] In this text, the "peel strength" is a value measured under the conditions of 23°C and 50% RH (relative humidity) when separating the adhesive film from an alkali-free glass plate set as the adherend at a peel rate of 2,400 mm / minute and a peel angle of 180°.

[0045] In this text, the "modulus" refers to the tensile modulus measured at 25°C. Specifically, the "modulus" is measured using a sample for modulus measurement. To prepare the specimen, the composition for the adhesive film is coated on one surface of a fluorinated film (FL-75BML, Dongwon Intec Co.) to a predetermined thickness and a polyethylene terephthalate (PET) film is attached to the coating, and then dried at 130°C for 4 minutes and aged at 50°C for 2 days to form a laminate, where a 75-μm-thick adhesive protective film is interposed between the fluorinated film and the PET film. Then, the laminate is cut into a dog-bone shape as shown in Figure 1 to prepare a sample by subsequently removing the fluorinated film and the PET film from the laminate.

[0046] Reference Figure 1 , the prepared sample has a dog-bone shape, with a total length of 40 mm, a total width of 15 mm, and a thickness of 75 μm. The modulus of the sample can be measured using a modulus tester (Instron Corp.). Specifically, the left end of the dog-bone-shaped sample shown in Figure 1 is connected to the first clamp of the modulus tester, and the right end of the sample is connected to the second clamp of the modulus tester. Here, the part of the left end connected to the first clamp has the same area as the part of the right end connected to the second clamp. Then, with the first clamp fixed in place, the sample is stretched on the second clamp until Figure 1 a part of the dog-bone-shaped sample breaks under the conditions of a load cell: 1 kN, a tensile rate: 50 mm / minute, and a temperature: 25°C, and this part is represented by a length of 15 mm and a width of 5 mm to measure the modulus of the sample.

[0047] In this text, the "number average molecular weight" can be measured by any typical method known to those skilled in the art or by referring to commercially available catalogs in the art. For example, the number average molecular weight can be obtained by gel permeation chromatography according to polystyrene standards.

[0048] As used in this text, to represent a specific numerical range, "X to Y" refers to a value greater than or equal to X and less than or equal to Y (X ≤ and ≤ Y).

[0049] An adhesive film for surface protection is a processing film that is used to temporarily protect an adherend and is removed from it after a predetermined time. The adhesive film is required to protect the adherend when attached to it and not deform and / or damage the adherend when removed from it. For this purpose, it is desirable for the adhesive film to have a peel strength within a predetermined range, but it is not limited thereto.

[0050] In one embodiment, the adhesive film for surface protection may have a peel strength (initial peel strength) of 4 gf / inch or less, for example, greater than 0 gf / inch, 0.5 gf / inch, 1 gf / inch, 1.5 gf / inch, 2 gf / inch, 2.5 gf / inch, 3 gf / inch, 3.5 gf / inch, or 4 gf / inch, specifically, greater than 0 gf / inch to 4 gf / inch, and more specifically, 1 gf / inch to 4 gf / inch. Within this range, the adhesive film can protect the adherend and can be removed from it without deforming and / or damaging the adherend.

[0051] The adhesive film for surface protection according to the present invention exhibits a low change in peel strength even after being placed for a long time under high temperature / humidity conditions. As a result, when the adhesive film is attached to the adherend again after being placed for a long time under high temperature / humidity conditions, the adhesive film can protect the adherend and can be removed from it without deforming and / or damaging the adherend.

[0052] On the other hand, when placed for a long time under high temperature / humidity conditions, due to the elution of components derived from it, such as plasticizers, a typical adhesive film for surface protection will suffer from surface contamination or poor appearance. When placed for a long time under high temperature / humidity conditions, due to an increase in the deviation of the peel strength, such contamination and poor appearance of the adhesive film will lead to failure in protecting the adherend. In addition, after being attached to the adherend, a typical adhesive film for surface protection also has to undergo the processes of assembly, inspection, handling, and transportation of a typical optical display. During these processes, the laminate of the adhesive film and the adherend can be cut into a predetermined size. Such contamination and poor appearance of the adhesive film will lead to failure during the cutting process.

[0053] Even after being placed for a long time under high temperature / humidity conditions, the adhesive film for surface protection according to the present invention does not allow any elution of components, especially plasticizers, therefrom to prevent surface contamination of the adhesive film, thereby ensuring good appearance. Therefore, the adhesive film of the present invention can protect the adherend and will not cause failure during the cutting process even after being placed for a long time under high temperature / humidity conditions.

[0054] Hereinafter, an adhesive film for surface protection (hereinafter referred to as "adhesive film") according to an embodiment of the present invention will be described.

[0055] The adhesive film according to the present invention has a peel strength change rate of -50% to 20% calculated according to Equation 1. Within this peel strength change rate range, when reattached to the adherend after being placed under high temperature / humidity conditions for a long time, the adhesive film can protect the adherend and can be removed from it without deforming and / or damaging the adherend. For example, the adhesive film can have a peel strength change rate of -50%, -49%, -48%, -47%, -46%, -45%, -44%, -43%, -42%, -41%, -40%, -39%, -38%, -37%, -36%, -35%, -34%, -33%, -32%, -31%, -30%, -29%, -28%, -27%, -26%, -25%, -24%, -23%, -22%, -21%, -20%, -19%, -18%, -17%, -16%, -15%, -14%, -13%, -12%, -11%, -10%, -9%, -8%, -7%, -6%, -5%, -4%, -3%, -2%, -1%, 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20% calculated according to Equation 1, especially a peel strength change rate of 30% to 20%:

[0056] [Equation 1]

[0057] Peel strength change rate = [(P2 – P1) / P1] x 100

[0058] Wherein, P1 is the initial peel strength of the adhesive film relative to an alkali-free glass plate (unit: gf / inch), and

[0059] P2 is the peel strength of the adhesive film relative to an alkali-free glass plate (unit: gf / inch) after being placed at 85°C and 85% RH for 10 days.

[0060] In one embodiment, the adhesive film can have a P1 value of 4 gf / inch or less. For example, greater than 0 gf / inch, 0.5 gf / inch, 1 gf / inch, 1.5 gf / inch, 2 gf / inch, 2.5 gf / inch, 3 gf / inch, 3.5 gf / inch or 4 gf / inch, specifically greater than 0 gf / inch to 4 gf / inch, preferably 1 gf / inch to 4 gf / inch. Within this range, the adhesive film can protect the adherend and can be removed from it without deforming and / or damaging the adherend.

[0061] In one embodiment, the adhesive film may have a P2 value of 4 gf / inch or less, for example, greater than 0 gf / inch, 0.5 gf / inch, 1 gf / inch, 1.5 gf / inch, 2 gf / inch, 2.5 gf / inch, 3 gf / inch, 3.5 gf / inch, or 4 gf / inch, specifically, greater than 0 gf / inch to 4 gf / inch, preferably, 1 gf / inch to 4 gf / inch, more preferably, 1.5 gf / inch to 4 gf / inch. Within this range, the adhesive film can protect the adherend and can be removed therefrom without deforming and / or damaging the adherend.

[0062] The adhesive film according to the present invention may have a modulus of 0.05 MPa to 0.8 MPa at 25°C. Within this range, with respect to the adherend to be attached thereto, the adhesive film can exhibit good wettability without generating bubbles and / or delamination, and can exhibit good resistance to scattering to ensure good cuttability and processability. For example, the adhesive film may have a modulus of 0.05 MPa, 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa, or 0.8 MPa at 25°C, specifically 0.1 MPa to 0.8 MPa, more specifically 0.5 MPa to 0.8 MPa.

[0063] For example, at a wavelength of 550 nm, in the visible spectrum, the adhesive film according to the present invention may have a turbidity of 5% or less, for example, 0%, 1%, 2%, 3%, 4%, or 5%, specifically, 0% to 1%. Within this range, the adhesive film has good cuttability and processability when cut after being adhered to the adherend.

[0064] The adhesive film according to the present invention may have a thickness of 100 μm or less, for example, greater than 0 μm to 75 μm. Within this range, the adhesive film can protect the adherend and can be easily removed therefrom.

[0065] The adhesive film according to the present invention may be formed from the composition for an adhesive film described below. In one embodiment, the adhesive film according to the present invention may include a cured product of the composition.

[0066] Next, a composition for an adhesive film according to one embodiment of the present invention will be described.

[0067] The composition for an adhesive film includes 100 parts by weight of a curable component, the curable component including a urethane-based binder; a curing agent; and 5 parts by weight to 20 parts by weight of a plasticizer.

[0068] Curable component

[0069] The curable component is cured by a curing agent to form a matrix of the adhesive film. According to Equation 1, the curing of the curable component by the curing agent enables the adhesive film to achieve a peel strength change rate in the range of -50% to 20%. Herein, the curable component refers to a component that can be cured by the following curing agent.

[0070] The curable component includes a urethane-based adhesive.

[0071] The urethane-based adhesive may have at least one urethane bond and at least one hydroxyl group (-OH). Having at least one hydroxyl group, the urethane-based adhesive is cured by a curing agent to form a matrix of the adhesive film while providing peel strength.

[0072] In the curable component of the composition for the adhesive film, the urethane-based adhesive may be present in an amount of 60 wt% to 100 wt%, for example, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt% or 100 wt%, specifically 60 wt% to less than 100 wt%, more specifically 60 wt% to 95 wt%. Within this range, the adhesive film can have sufficient peel strength.

[0073] The urethane-based adhesive may have a number average molecular weight of 30,000 to 150,000, for example, 30,000, 35,000, 40,000, 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, 105,000, 110,000, 115,000, 120,000, 125,000, 130,000, 135,000, 140,000, 145,000 or 150,000, specifically 50,000 to 70,000. Within this range, the adhesive film can easily achieve the peel strength and modulus according to the present invention while ensuring good wettability.

[0074] The urethane-based adhesive can be prepared by the reaction of at least one type of polyol with at least one polyisocyanate compound. The urethane-based adhesive may be a random copolymer having units derived from the polyol.

[0075] The polyol may include at least one selected from polyether-based polyols, polyester-based polyols, polyacrylic acid-based polyols, polycaprolactone-based polyols, and polycarbonate-based polyols. Preferably, the polyol includes at least one polyether-based polyol and further includes at least one polyester-based polyol.

[0076] The urethane-based adhesive may include units derived from polyether-based polyols. The urethane-based adhesive may also include units derived from polyester-based polyols.

[0077] The polyether-based polyol has an alkylene oxide group and is preferably a polyether-based polyol having at least two hydroxyl groups, such as a bifunctional polyether polyol (polyether-based diol) or a trifunctional polyether polyol (polyether-based triol), such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc., and a trifunctional polyether-based polyol (polyether-based triol) of a glycerol alkylene oxide adduct. The urethane-based adhesive can be made into a hyperbranched adhesive to have a better tissue structure than a linear structure, thereby making it easier to achieve the effects of the present invention. Here, "hyperbranched" means a polymer having a dendritic branched structure with many end groups.

[0078] At least one or two types of polyether-based polyols can be used in the preparation of the urethane-based adhesive.

[0079] The polyether-based polyol may have a number average molecular weight of 400 to 10,000, for example, 400, 500, 1000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, 10,000, specifically 1,000 to 7,000. Within this range, the adhesive film can easily achieve the peel strength and modulus according to the present invention while ensuring good wettability.

[0080] In the preparation of the urethane-based adhesive, based on the total amount of the polyol used to prepare the urethane-based adhesive, the polyether polyol may be present in an amount of 50 wt% to 100 wt%, for example, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt% or 100 wt%, specifically 50 wt% to 99 wt%. Within this range, the adhesive film can easily achieve the effects of the present invention.

[0081] Preferably, the polyether-based polyol includes a mixture of polyether-based diol and polyether-based triol to easily achieve the effects of the present invention.

[0082] For example, in the preparation of an urethane-based adhesive, based on the total amount of polyols used to prepare the urethane-based adhesive, the polyether-based triol may be present in an amount of 50 wt% to 95 wt%, for example, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt% or 95 wt%, specifically 50 wt% to 90 wt%, and based on the total amount of polyols used to prepare the urethane-based adhesive, the polyether-based diol may be present in an amount of 5 wt% to 50 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt% or 50 wt%, specifically 5 wt% to 40 wt%, more specifically 10 wt% to 50 wt%. Within this range, the adhesive film can easily achieve the effects of the present invention.

[0083] In one embodiment, the polyether-based diol may have a number average molecular weight of 400 to 10,000, for example, 400, 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500 or 10,000, especially 1,000 to 6,000. Within this range, the adhesive film can easily achieve the peel strength and modulus according to the present invention while ensuring good wettability.

[0084] [[ID={7]]In one embodiment, the polyether-based triol may have a number average molecular weight of 400 to 10,000, for example, 400, 500, 1000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500 or 10,000, specifically 2,000 to 8,000. Within this range, the adhesive film can easily achieve the peel strength and modulus according to the present invention while ensuring good wettability.

[0085] In one example, the urethane-based adhesive may be prepared from at least one polyisocyanate compound and a polyol comprising 50 wt% to 95 wt% polyether-based triol and 5 wt% to 50 wt% polyether-based diol. Within this range, the adhesive film can easily achieve the effects of the present invention.

[0086] The polyester-based polyol may include a polyol obtained by esterification between at least one type of polyol and at least one type of acidic component.

[0087] Here, the polyol may include at least one selected from the group consisting of ethylene glycol, propylene 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, 2-ethyl-1,3-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerol, trimethylolpropane, pentaerythritol, and hexanetriol, but is not limited thereto. The acidic component may be succinic acid, methylsuccinic acid, adipic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, or their acid anhydrides, but is not limited thereto.

[0088] In the preparation of the urethane-based adhesive, one or two types of polyester-based polyols may be used.

[0089] The polyester-based polyol, for example, the polyester-based diol, may have a number average molecular weight of 1,000 to 5,000, such as 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, or 5,000, specifically 2,000 to 3,000. Within this range, the adhesive film can easily achieve the peel strength and modulus according to the present invention.

[0090] In the preparation of the urethane-based adhesive, based on the total amount of the polyol used for preparing the urethane-based adhesive, the polyester-based polyol may optionally be present in an amount of 0 wt% to 50 wt%, such as 0 wt%, greater than 0 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%, specifically 1 wt% to 50 wt%, more specifically 5 wt% to 40 wt%. Within this range, the adhesive film can easily achieve the effects of the present invention.

[0091] The polyester-based polyol may include a polyester-based polyol having at least two hydroxyl groups, such as a bifunctional polyester-based polyol (polyester-based diol) or a trifunctional polyester-based polyol (polyester-based triol). As a result, the urethane-based adhesive becomes a hyperbranched adhesive, enabling the effects of the present invention to be easily implemented. Preferably, a polyester-based diol is used as the polyester-based polyol.

[0092] In one embodiment, the urethane-based adhesive may be prepared from at least one polyisocyanate compound and a polyol, the polyol comprising 50 wt% to 90 wt% of a polyether-based triol, 5 wt% to 40 wt% of a polyether-based diol, and 5 wt% to 40 wt% of a polyester-based diol. Within this range, the adhesive film can easily achieve the effects of the present invention.

[0093] The polyisocyanate compound may include a polyisocyanate compound containing a plurality of isocyanate groups (-NCO). The polyisocyanate compound may be selected from typical polyisocyanate compounds known in the art and may include at least one selected from aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and aromatic alicyclic polyisocyanates. In particular, aliphatic polyisocyanates are preferred.

[0094] The aliphatic polyisocyanate compound may include at least one selected from hexamethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, but is not limited thereto.

[0095] Relative to 100 parts by weight of all polyols, the polyisocyanate compound may be present in an amount of 1 part by weight to 10 parts by weight, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight, specifically 1 part by weight to 5 parts by weight. Within this range, the urethane-based adhesive according to the present invention can be easily prepared.

[0096] The reaction may be carried out at a predetermined temperature after adding a catalyst to a mixture comprising at least one type of polyol and at least one type of polyisocyanate compound.

[0097] The catalyst may be a tin compound, including dibutyltin dilaurate (DBTDL) and sodium 2-ethylhexanoate, but is not limited thereto.

[0098] The urethane-based adhesive can be prepared by heating a polyol mixture in a reactor under a nitrogen atmosphere at 80°C to 100°C for 10 minutes to 30 minutes until moisture is completely removed from the reactor, reducing the internal temperature of the reactor to 65°C to 70°C, adding a polyisocyanate compound and a catalyst to the reactor, then subjecting it to primary polymerization at 65°C to 75°C for 3 hours to 4 hours, and secondary polymerization at 75°C to 85°C for 60 minutes to 120 minutes.

[0099] In one embodiment, the urethane-based adhesive can be a (meth)acrylate-free urethane-based adhesive that does not contain (meth)acrylate groups.

[0100] The curable composition may further contain a polyol.

[0101] The polyol has at least one hydroxyl group to further reduce the rate of change of peel strength.

[0102] The polyol may further include at least one selected from polyether-based polyols, polyester-based polyols, polycaprolactone-based polyols, and polycarbonate-based polyols. Preferably, the polyol is a polyether-based polyol.

[0103] The polyether-based polyol has an alkylene oxide group and is preferably a polyether-based polyol having at least two hydroxyl groups, for example, a bifunctional polyether-based polyol (polyether diol) or a trifunctional polyether-based polyol (polyether triol), such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc., a trifunctional polyether-based polyol (polyether triol) of a glycerol alkylene oxide adduct, etc.

[0104] The polyester-based polyol may include a polyol obtained by esterification between at least one type of polyol and at least one type of acidic component. Here, the polyol and the acidic component are the same as those described above.

[0105] The polyol may have a number average molecular weight of 400 to 10,000, for example, 400, 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, or 10,000, especially 1,000 to 7,000. Within this range, the adhesive film can easily achieve the peel strength and modulus according to the present invention while ensuring good wettability.

[0106] In the curable component, the polyol may be present in an amount of 0 wt% to 40 wt%, for example, more than 0 wt%, greater than 0 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt% or 50 wt%, for example, 0 wt% to less than 40 wt%, specifically, 5 wt% to 40 wt%. Within this range, the adhesive film can ensure the inherent effect of the polyol.

[0107] Relative to 100 parts by weight of the urethane-based adhesive, the polyol may be present in an amount of 0 to 70 parts by weight, for example, 0 parts by weight or more, greater than 0 parts by weight, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65 or 70 parts by weight, specifically greater than 0 to 70 parts by weight, more specifically 15 parts by weight to 70 parts by weight. Within this range, the adhesive film can ensure the inherent effect of the polyol.

[0108] Curing agent

[0109] The curing agent can cure the curable component to provide peel strength to the adhesive film. In one embodiment, the curing agent may be a thermosettable curing agent.

[0110] Using at least one isocyanate group (-NCO), the curing agent can react with the hydroxyl groups in the urethane-based adhesive and / or polyol to provide the matrix of the adhesive film while providing peel strength to the adhesive film.

[0111] The isocyanate-based curing agent is a polyfunctional isocyanate-based curing agent having a plurality of isocyanate groups and may include typical isocyanate-based curing agents known to those skilled in the art.

[0112] In one embodiment, the isocyanate-based curing agent may include at least one selected from aliphatic isocyanate compounds, alicyclic isocyanate compounds, aromatic isocyanate compounds, and araliphatic isocyanate compounds, their polyol adducts, their biurets, or their isocyanurates. For example, aliphatic isocyanate compounds may include at least one selected from hexamethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate, but are not limited thereto. For example, aromatic isocyanate compounds may include at least one selected from toluene diisocyanate, xylylene diisocyanate, and phenylene diisocyanate, but are not limited thereto.

[0113] Preferably, the isocyanate-based curing agent includes an isocyanurate of the isocyanate-based curing agent. By combining the isocyanurate curing agent with the composition according to the present invention containing a urethane-based binder and a plasticizer, the effects of the present invention can be easily achieved.

[0114] In one embodiment, relative to all curing agents in 100 parts by weight of the composition, the isocyanate-based curing agent may be present in an amount of 80 parts by weight or more, for example, 90 parts by weight to 100 parts by weight.

[0115] Relative to 100 parts by weight of the curable components, the curing agent may be present in an amount of 1 part by weight to 10 parts by weight, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight, specifically 2 parts by weight to 6 parts by weight. Within this range, the curing agent can contribute to the formation of an adhesive film having the effects of the present invention.

[0116] Plasticizer

[0117] The plasticizer can ensure resistance to scattering during the cutting process by suppressing an increase in the modulus of the adhesive film. Here, "resistance to scattering" means that no scattered particles are generated when cutting the adhesive film or a laminate of the adhesive film and the adherend.

[0118] Relative to 100 parts by weight of the curable components, the plasticizer may be present in an amount of 5 parts by weight to 20 parts by weight. Within this range, even after the adhesive film is placed under high temperature / humidity conditions for a long time, the plasticizer can help achieve a peel strength change rate of -50% to 20% and can prevent its elution. For example, relative to 100 parts by weight of the curable components, the plasticizer may be present in an amount of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 parts by weight, especially 10 parts by weight to 20 parts by weight.

[0119] The plasticizer may be an ester-based plasticizer and may include esters of C6-C 18 monocarboxylic acids or polycarboxylic acids and C3-C 18 branched-chain alcohols, esters of C 14 -C 18 unsaturated fatty acids or branched-chain acids and tetravalent or lower alcohols, and esters of C6-C 10 monocarboxylic acids or polycarboxylic acids and polyalkylene glycols.

[0120] In one embodiment, the plasticizer may have one or more ester groups represented by the following formula 1. Since the ester group has a branched terminal CH(CH3)2 as shown in formula 1, even after being placed under high temperature / humidity conditions for a long time, the adhesive film can protect the adherend while reducing the peel strength change rate.

[0121] [Formula 1]

[0122] *-C(=O)-O-X-CH(CH3)2,

[0123] where * is the bonding site of the element and X is a single bond or a divalent organic group.

[0124] In one embodiment, X is a single bond or a straight-chain or branched C6-C 20 alkylene.

[0125] In one embodiment, the plasticizer may have one or more ester groups represented by the following formula 2. Since the ester group has a branched terminal CH(CH3)2 as shown in formula 2, even after being placed for a long time under high temperature / humidity conditions, the adhesive film can protect the adherend while reducing the change rate of the peel strength.

[0126] [Formula 2]

[0127] *-C(=O)-O-X1-CH2-CH(CH3)2,

[0128] where * is the bonding site of the element and X1 is a single bond or a straight-chain divalent organic group.

[0129] In one embodiment, X1 is a single bond or a straight-chain C6-C 20 alkylene.

[0130] For example, the plasticizer may include at least one selected from the following: isopropyl myristate, isopropyl palmitate, isotridecyl isononanoate, diisononyl 1,2-cyclohexanedicarboxylate, isostearyl palmitate, isostearyl laurate, diisostearyl adipate, and diisocetyl sebacate, but is not limited thereto.

[0131] Relative to 100 parts by weight of all plasticizers in the adhesive film or the composition for the adhesive film, the plasticizer, the ester of formula 1, the ester of formula 2, or at least one selected from isopropyl myristate, isopropyl palmitate, isotridecyl isononanoate, diisononyl 1,2-cyclohexanedicarboxylate, isostearyl palmitate, isostearyl laurate, diisostearyl adipate, and diisocetyl sebacate may be present in an amount of 80 parts by weight or more, preferably 90 parts by weight to 100 parts by weight.

[0132] The adhesive film may further include at least one selected from a crosslinking catalyst, a leveling agent, an antistatic agent, an antioxidant, and a retarder.

[0133] The crosslinking catalyst can promote the reaction between the curable component and the curing agent.

[0134] The crosslinking catalyst can be at least one metal-based catalyst. The metal-based catalyst can include a tin-based catalyst and / or a non-tin-based catalyst. Each of the tin-based catalyst and the non-tin-based catalyst can be selected from typical types well-known to those skilled in the art. For example, the tin-based catalyst can include dibutyltin dichloride, dibutyltin oxide, dibutyltin dilaurate, dibutyltin sulfide, dibutyltin diacetate, and dibutyltin maleate, but is not limited thereto.

[0135] Relative to 100 parts by weight of the curable component, the crosslinking catalyst can be present in an amount of 0.005 parts by weight to 0.5 parts by weight, specifically 0.005 parts by weight to 0.1 parts by weight. Within this range, the crosslinking catalyst can ensure a satisfactory pot life and rapid curing.

[0136] The leveling agent can enhance the leveling performance of the adhesive film. The leveling agent can include acrylic leveling agents, fluorine-based leveling agents, silicone-based leveling agents, and silicone-acrylate leveling agents.

[0137] Relative to 100 parts by weight of the curable component, the leveling agent can be present in an amount of 0.1 parts by weight to 5 parts by weight, specifically 0.1 parts by weight to 1 part by weight. Within this range, the adhesive film can provide a low initial peel strength.

[0138] The antistatic agent can prevent damage to the adherend by suppressing the generation of static electricity during the process of removing the adhesive film from the adherend after the adhesive film is attached. The antistatic agent can include typical antistatic agents well-known to those skilled in the art. For example, the antistatic agent can include ionic liquids.

[0139] Relative to 100 parts by weight of the curable component, the antistatic agent can be present in an amount of 0.01 parts by weight to 5 parts by weight, specifically 0.01 parts by weight to 1 part by weight. Within this range, the antistatic agent can ensure its inherent properties without affecting the various properties of the adhesive film.

[0140] The antioxidant can ensure the peel strength by separating the adhesive film from the external environment to inhibit the peeling of the adhesive film. The antioxidant can include typical antioxidants well-known to those skilled in the art. For example, the antioxidant can include cinnamate esters, phenols, sulfur, phosphorus, and HALS-based antioxidants.

[0141] Relative to 100 parts by weight of the curable component, the antioxidant can be present in an amount of 0.01 parts by weight to 5 parts by weight, specifically 0.01 parts by weight to 1 part by weight. Within this range, the antioxidant can ensure its inherent properties without affecting the various properties of the adhesive film.

[0142] The retarder can include typical retarders well-known to those skilled in the art. For example, the retarder can include acetylacetone or its complexes.

[0143] Relative to 100 parts by weight of the curable component, the retarder may be present in an amount of 0.01 to 5 parts by weight, specifically 0.01 to 3 parts by weight. Within this range, the retarder can ensure its inherent properties without affecting the various properties of the adhesive film.

[0144] The composition for the adhesive film may further comprise additives. The additives may include, but are not limited to, UV absorbers, UV stabilizers, heat stabilizers, surfactants, fillers, and pigments.

[0145] The adhesive film can be manufactured by coating the composition for the adhesive film on a base film to a predetermined thickness and drying the composition at 110°C to 140°C, and then leaving the composition at 30°C to 70°C for 1 to 3 days, but is not limited thereto.

[0146] An optical member according to an embodiment of the present invention includes an optical film and an adhesive film for surface protection formed on the surface of the optical film, wherein the adhesive film for surface protection includes the adhesive film for surface protection according to an embodiment of the present invention.

[0147] The optical film may include a polyimide film as a display panel. In one embodiment, the optical film may be composed of a light-emitting diode layer and a polyimide layer formed on at least one surface of the light-emitting diode layer. An organic insulating layer or an inorganic insulating layer may be further formed between the optical film and the silicone-based adhesive protective film. The optical member may further include a release film (liner) on the other surface of the adhesive protective film. The release film can prevent the adhesive protective film from being contaminated by foreign substances. The release film may be formed of the same material or a different material as the optical film. For example, the release film may be formed of at least one resin selected from polyethylene terephthalate resin, polycarbonate resin, polyimide resin, poly(meth)acrylate resin, cycloolefin polymer resin, and acrylic resin. The release film may have a thickness of 10 μm to 100 μm, preferably 10 μm to 50 μm. Within this range, the release film can support the adhesive protective film.

[0148] Next, the present invention will be described in more detail with reference to the examples. However, it should be noted that these examples are provided for illustrative purposes only and should not be construed as limiting the present invention in any way.

[0149] Example 1

[0150] Under nitrogen purging conditions, 100 parts by weight of a polyol comprising 70 parts by weight of PPG-3020, 15 parts by weight of PPG-6000, and 15 parts by weight of P-2010 was placed in a 1,000 mL jacketed reactor. Then, toluene was further added thereto to prepare a mixture, which was then stirred for 10 minutes under nitrogen purging conditions and heated to 85 °C for 30 minutes to remove residual moisture. Next, the internal temperature of the reactor was lowered to 60 °C, and 4 parts by weight of hexamethylene diisocyanate was added to the mixture. The mixture was further stirred at 60 °C for 10 minutes, and dibutyltin dilaurate (DBTDL) as a catalyst was added. After 1 hour, the internal temperature of the reactor was raised to 70 °C, followed by a polymerization reaction for 6 hours. Then, the resulting urethane-based adhesive solution was diluted with toluene to prepare a solution having a solids content of 65 wt%, which was then cooled to room temperature to prepare a solid compound. The solid compound contained the urethane adhesive TOH-12.

[0151] A composition for an adhesive film was prepared by the following steps: 100 parts by weight of the urethane-based adhesive TOH-12, 4.8 parts by weight of an isocyanate curing agent (Coronate HX), 0.4 parts by weight of a leveling agent (BYK-SILCLEAN 3700, BYK), 15 parts by weight of a plasticizer (isopropyl myristate), 0.25 parts by weight of an antistatic agent (FC-4400), 0.25 parts by weight of an antioxidant (Irganox 1010), 0.01 parts by weight of a crosslinking catalyst (catalyst S, DBTDL), and 1.5 parts by weight of a retarder (acetylacetone) based on the solids content were mixed, and then methyl ethyl ketone was added to the mixture.

[0152] The prepared composition was deposited to a predetermined thickness on the upper surface of a release film (PET film, thickness: 75 μm, TU73A, SKC) using a film coater and dried at 130 °C for 4 minutes. Then, a release film (PET film having an antistatic coating formed thereon, thickness: 25 μm) was placed on the composition layer, and the resulting product was left at 50 °C for 2 days, thereby producing an adhesive sheet including a base film, an adhesive film (thickness: 75 μm), and a release film.

[0153] Example 2

[0154] The composition for an adhesive film and the adhesive sheet were prepared in the same manner as in Example 1, except that the types and / or contents of various components of the composition for an adhesive film were changed as listed in Table 1. In Table 1, "-" means that the corresponding component is absent, and the unit is parts by weight.

[0155] Examples 3 and 4

[0156] The composition for the adhesive film and the adhesive sheet were prepared in the same manner as in Example 1, except that 85 parts by weight of the prepared urethane-based adhesive TOH-12 and 15 parts by weight of PPG-7000 as a polyol were mixed based on the solid content, and the types and / or contents of various components of the composition for the adhesive film were changed as listed in Table 1.

[0157] Example 5

[0158] The composition for the adhesive film and the adhesive sheet were prepared in the same manner as in Example 1, except that 60 parts by weight of the urethane-based adhesive SH101 and 40 parts by weight of PPG-7000 as a polyol were mixed based on the solid content, and the types and / or contents of each component of the composition for the adhesive film were changed as listed in Table 1.

[0159] Comparative Example 1

[0160] The composition for the adhesive film and the adhesive sheet were prepared in the same manner as in Example 1, except that 60 parts by weight of the urethane-based adhesive SH101 and 40 parts by weight of PPG-7000 as a polyol were mixed based on the solid content, and the types and / or contents of each component of the composition for the adhesive film were changed as listed in Table 1.

[0161] Comparative Example 2

[0162] The composition for the adhesive film and the adhesive sheet were prepared in the same manner as in Example 1, except that 60 parts by weight of the urethane-based adhesive TOH-12 and 40 parts by weight of PPG-7000 as a polyol were mixed based on the solid content, and the types and / or contents of each component of the composition for the adhesive film were changed as listed in Table 1.

[0163] Comparative Example 3

[0164] The composition for the adhesive film and the adhesive sheet were prepared in the same manner as in Example 1, except that the types and / or contents of each component of the composition for the adhesive film were changed as listed in Table 1. In Table 1, "-" means that the corresponding component is absent, and the unit is parts by weight.

[0165] Details of the components of the composition for the adhesive film prepared in the examples and comparative examples are shown in Table 1.

[0166] Table 1

[0167]

[0168] Table 2 shows the components used in the examples and comparative examples.

[0169] Table 2

[0170]

[0171] Evaluate the following properties of the compositions for adhesive films and / or the adhesive films for surface protective films prepared in the examples and comparative examples, and show the results in Table 3.

[0172] (1) Initial peel strength (unit: gf / inch): Cut each adhesive sheet prepared in the examples and comparative examples into a size of 200 mm × 25 mm (length × width), and expose the adhesive film by removing the PET release film from the adhesive sheet. Then, attach a non-alkali glass plate to the exposed surface of the adhesive film and press it once with a 2 kg roller to obtain a specimen of a laminate having a glass plate, an adhesive film, and a base film. Measure the initial peel strength according to JIS Z0237.

[0173] Thirty minutes after preparing the specimen, use a texture analyzer (TA Industry) as the device for measuring the peel strength, and measure the peel strength of the adhesive film with respect to the glass plate under the conditions of a peel rate of 2,400 mm / minute, a peel angle of 180°, a temperature of 23°C, and 50% RH (relative humidity). Here, the peel strength is measured three times, and then the average value of the measured values is calculated.

[0174] (2) Appearance (bubble generation): After removing the PET release film from each adhesive sheet prepared in the examples and comparative examples, check for bubble generation on the exposed surface of the adhesive film. No bubble generation is rated as OK, and slight or severe bubble generation is rated as NG.

[0175] (3) Peel strength change rate (unit: %): Cut each adhesive sheet prepared in the examples and comparative examples into a size of 200 mm × 25 mm (length × width), and expose the adhesive film by removing the PET release film from the adhesive sheet. Place the laminate of the adhesive film and the base film at 85°C and 85% RH for 10 days. Then, attach a non-alkali glass plate to the exposed surface of the adhesive film and press it once with a 2 kg roller to obtain a specimen of a laminate including a glass plate, an adhesive film, and a base film.

[0176] Measure the peel strength by the same method as in (1), and then calculate the peel strength change rate according to Equation 1.

[0177] (4) Appearance after testing under high temperature / humidity conditions (dissolution of plasticizer): The laminate of the release film / adhesive film / release film prepared in each of the examples and comparative examples was placed at 85°C and 85% RH for 10 days. The dissolution of the plasticizer was examined on the surface of the adhesive film. The dissolution of the plasticizer was examined with the naked eye. A specimen having a clean adhesive film surface due to no dissolution of the plasticizer was rated as OK, and a specimen having an unclean adhesive film surface due to dissolution of the plasticizer was rated as NG.

[0178] Table 3

[0179]

[0180]

[0181] As shown in Table 3, the adhesive film for a surface protective film according to the present invention has an initial peel strength of 4 gf / inch or less. Therefore, although not shown in Table 3, the adhesive film according to the present invention can protect the adherend and can be removed from it without deforming and / or damaging the adherend. In addition, the adhesive film of the present invention has a small change in peel strength even after being placed under high temperature / humidity conditions for a long time. Therefore, the adhesive film of the present invention can be attached to the adherend to protect the adherend, and even after being placed under high temperature / humidity conditions for a long time, it will not cause deformation and / or damage to the adherend and can be easily removed. In addition, the appearance of the adhesive film of the present invention is good, and even after being placed under high temperature / humidity conditions for a long time, it can prevent failure when cutting the laminate of the adhesive film and the adherend.

[0182] In contrast, the adhesive films of the comparative examples failed to achieve all the effects of the present invention.

[0183] It should be understood that various modifications, changes, alterations, and equivalent embodiments can be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. An adhesive film for surface protection, which is formed from a composition for an adhesive film, the composition for the adhesive film comprising a curable component containing a urethane-based adhesive, a curing agent, and a plasticizer, and the adhesive film having a peel strength change rate of -26% to 20% calculated by Equation 1: [Equation 1] Peel strength change rate = [(P2 – P1) / P1] x 100 Among them, P1 is the initial peel strength of the adhesive film relative to an alkali-free glass plate, and P2 is the peel strength of the adhesive film relative to the alkali-free glass plate after being placed at 85 °C and 85% RH for 10 days, The units of P1 and P2 are gf / inch, and the unit of the peel strength change rate is %, wherein the peel strength is measured according to JIS Z0237, wherein the urethane-based adhesive is formed from at least one polyisocyanate compound and a polyol, the polyol comprising 50 wt% to 90 wt% of a polyether-based triol, 5 wt% to 40 wt% of a polyether-based diol, and 5 wt% to 40 wt% of a polyester-based diol, wherein the polyether-based diol has a number average molecular weight of 400 to 10,000, the polyether-based triol has a number average molecular weight of 400 to 10,000, and the polyester-based diol has a number average molecular weight of 1,000 to 5,000, and wherein the urethane-based adhesive has a number average molecular weight of 30,000 to 150,000, wherein the polyisocyanate compound is present in an amount of 1 part by weight to 10 parts by weight relative to 100 parts by weight of the polyol, wherein the plasticizer is present in an amount of 5 parts by weight to 20 parts by weight relative to 100 parts by weight of the curable component, wherein the plasticizer is an ester compound having one or more ester groups represented by Formula 1: [Formula 1] *-C(=O)-O-X-CH(CH3)2, where * is the bonding site of the element and X is a single bond or a divalent organic group, wherein the ester compound comprises at least one selected from isopropyl myristate, isopropyl palmitate, isotridecyl isononanoate, diisononyl 1,2-cyclohexanedicarboxylate, isostearyl palmitate, isostearyl laurate, diisostearyl adipate, and diisocetyl sebacate.

2. The adhesive film for surface protection according to claim 1, wherein the adhesive film has a P1 value of 4 gf / inch or less and a P2 value of 4 gf / inch or less.

3. The adhesive film for surface protection according to claim 1, wherein the urethane-based adhesive is a hyperbranched adhesive.

4. The adhesive film for surface protection according to claim 1, wherein the curable component further comprises a polyol.

5. The adhesive film for surface protection according to claim 4, wherein the polyol further comprised in the curable component is present in an amount of more than 0 to 70 parts by weight relative to 100 parts by weight of the urethane-based adhesive.

6. The adhesive film for surface protection according to claim 4, wherein the polyol further included in the curable component includes at least one selected from polyether-based polyols and polyester-based polyols.

7. The adhesive film for surface protection according to claim 6, wherein the polyester-based polyol includes at least one selected from polycaprolactone-based polyols and polycarbonate-based polyols.

8. The adhesive film for surface protection according to claim 1, wherein the curing agent includes an isocyanate-based curing agent and is present in an amount of 1 to 10 parts by weight relative to 100 parts by weight of the curable component.

9. The adhesive film for surface protection according to claim 1, wherein the curing agent includes an isocyanate-based curing agent of isocyanurates.

10. The adhesive film for surface protection according to claim 1, which further comprises; at least one selected from crosslinking catalysts, leveling agents, antistatic agents, antioxidants, and retarders.

11. An optical member, comprising: Optical film; and an adhesive film for surface protection according to any one of claims 1 to 10, the adhesive film being formed on one surface of the optical film.

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