Adhesive film for surface protection film and optical member including same

Abstract

The adhesive film for surface protection film is formed from a composition containing a urethane binder and an isocyanate curing agent, and the adhesive film has a peel strength increase rate of 180% or less as shown in Equation 1, an initial peel strength of 1 gf / inch to 12 gf / inch, a nitrogen content of 0.5 wt% to 1.5 wt%, and a modulus at 25°C of 0.05 MPa to 0.8 MPa. An adhesive film for surface protection film and an optical component including the same are provided.

Description

[Technical field]

[0001] The present invention relates to an adhesive film for surface protection films and an optical member including the same. [Background technology]

[0002] The use, storage and manufacturing environments of optical display devices are becoming harsher. Also, interest in new optical display devices such as wearable devices and foldable devices is growing. Accordingly, various physical properties are required for adhesive protective films that protect panels of optical display devices. In particular, as panels of optical display devices are becoming thinner and more flexible, there is a demand for the development of adhesive protective films that cause less damage to the panel when the adhesive protective film is removed and that undergo little change in physical properties even under harsh conditions.

[0003] For this reason, acrylate-based or urethane acrylate-based adhesive protective films have been developed. However, acrylate-based or urethane acrylate-based adhesive protective films have limitations in that when the adhesive protective film is attached to an adherend and then left for a long period of time, the peeling force against the adherend increases excessively, which may cause damage and / or deformation of the adherend when peeled from the adherend, and the adhesive protective film is difficult to remove from the adherend, which may reduce processability.

[0004] The background art of the present invention is disclosed in Korean Patent Publication No. 2012-0050136 and the like. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an adhesive film for surface protection films which simultaneously provides a temporary protective effect for an adherend and an effect of being removable from the adherend without deforming and / or damaging the adherend.

[0006] Another object of the present invention is to provide an adhesive film for surface protection films, which has a low rate of increase in peel strength after adhering to an adherend.

[0007] It is still another object of the present invention to provide an adhesive film for surface protection films which provides good wetting properties to an adherend and good shatterproof properties.

[0008] Still another object of the present invention is to provide an adhesive film for surface protection films, which has low haze and is therefore excellent in cuttability and processability. [Means for solving the problem]

[0009] One aspect of the present invention is an adhesive film for use as a surface protective film.

[0010] 1. The adhesive film for surface protection film is formed from a composition for adhesive film including a urethane-based binder and an isocyanate-based curing agent, and the adhesive film has an increase rate of peel strength of 180% or less as shown in the following formula 1:

[0011]

number

[0012] (In the above formula 1, P1 is the initial peel strength of the adhesive film (unit: gf / inch), P2 is the peel strength (unit: gf / inch) of the adhesive film after leaving the adhesive film at 50°C for 3 days and then leaving it at 25°C for 30 minutes. The adhesive film has an initial peel strength of 1 gf / inch to 12 gf / inch, The adhesive film has a nitrogen (N) atom content of 0.5 wt % to 1.50 wt % of the total atoms, and the adhesive film has a modulus at 25° C. of 0.05 MPa to 0.8 MPa.

[0013] In 2.1, the adhesive film may have a haze of 5% or less in the visible light region.

[0014] In 3.1 to 2, the pressure-sensitive adhesive film may have a peel strength of 12 gf / inch or less after being left at 50° C. for 3 days and then at 25° C. for 30 minutes.

[0015] In 4.1 to 3, the urethane binder may contain units derived from a polyether polyol.

[0016] In 5.4, the urethane-based binder may further contain units derived from a polyester-based polyol.

[0017] In 6.1 to 6.5, the urethane binder may be hyperbranched.

[0018] In 7.1 to 7.6, the urethane-based binder may be made from a polyol containing 40% by weight to 95% by weight of a triol and 5% by weight to 60% by weight of a diol.

[0019] In 8.1 to 7, the ratio of the total number of moles of isocyanate groups of the isocyanate curing agent to the total number of moles of hydroxyl groups of the urethane binder may be 0.7 to 1.2.

[0020] In 9.1 to 8, the isocyanate-based curing agent may contain an isocyanurate of an aliphatic polyisocyanate-based, alicyclic polyisocyanate-based, aromatic polyisocyanate-based, or araliphatic polyisocyanate-based curing agent.

[0021] In 10.1 to 9, the isocyanate-based curing agent may be contained in an amount of 2 to 10 parts by weight based on 100 parts by weight of the urethane-based binder.

[0022] In 11.1 to 10, the composition may further include one or more of a crosslinking catalyst, a plasticizer, and a leveling agent.

[0023] In 12.11, the plasticizer can include one or more of esters of monobasic acids or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms, esters of unsaturated fatty acids or branched acids having 14 to 18 carbon atoms and tetrahydric or less alcohols, and esters of monobasic acids or polybasic acids having 6 to 10 carbon atoms and polyalkylene glycols.

[0024] The optical member of the present invention includes an optical film, and the pressure-sensitive adhesive film for surface protection film of the present invention formed on at least one surface of the optical film. Effect of the Invention

[0025] The present invention can provide an adhesive film for surface protection films that simultaneously provides a temporary protective effect for an adherend and an effect of being removable from the adherend without deforming and / or damaging the adherend.

[0026] The present invention can provide an adhesive film for surface protection films that has a low rate of increase in peel strength after adhering to an adherend.

[0027] The present invention can provide a pressure-sensitive adhesive film for surface protection films that provides good wetting properties to an adherend and good shatterproof properties.

[0028] The present invention can provide an adhesive film for surface protection films that has low haze and is therefore excellent in cuttability and processability. [Brief description of the drawings]

[0029] [Figure 1] FIG. 2 is a plan view of a test piece for measuring the modulus of an adhesive film for a surface protective film in an experimental example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] [Best Mode for Carrying Out the Invention] Hereinafter, each embodiment of the present invention will be described in more detail. However, the technology disclosed in the present application is not limited to each embodiment described herein, and may be embodied in other forms. However, each embodiment introduced herein is provided so that the disclosed content may be thorough and complete, and to fully convey the idea of ​​the present application to those skilled in the art.

[0031] In this specification, the "modulus" of the adhesive film means the tensile modulus measured at 25°C.

[0032] In this specification, the "adherend" may include, but is not limited to, a glass plate, a plastic plate, a display panel, or the like.

[0033] In this specification, when describing a numerical range, "X to Y" means X or more and Y or less (X≦and≦Y).

[0034] The adhesive film for surface protection films of the present invention (hereinafter referred to as "adhesive film") temporarily protects the adherend while adhering to the adherend, and when removed from the adherend, can be removed without causing deformation and / or damage to the adherend. Since the adhesive film of the present invention has a low rate of increase in peel force after adhering to the adherend, it can be removed from the adherend without causing deformation and / or damage to the adherend even after adhering to the adherend for a long period of time.

[0035] The adhesive film of the present invention has good wetting properties when adhered to an adherend, so it can adhere well to the adherend without the generation of air bubbles and / or lifting, and after adhering to the adherend, it has good shatter-proof properties when cut, improving cuttability and processability.

[0036] The pressure-sensitive adhesive film of the present invention has low haze, which facilitates inspection of panels for foreign matter after adhesion to an adherend, and provides excellent processability.

[0037] An adhesive film according to an embodiment of the present invention will now be described.

[0038] The adhesive film has a modulus of 0.05 MPa to 0.8 MPa at 25° C. In this range, the adhesive film has good wetting ability, so that it can adhere to an adherend without generating bubbles and / or lifting, and has good shatter resistance, so that it can have excellent cuttability and processability. Specifically, 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, 0.8 MPa, specifically 0.1 MPa to 0.8 MPa, more specifically 0.5 MPa to 0.8 MPa. The "shatter-resistant" property means that no particles are generated when a laminate of an adhesive film and an adherend is scratched using a pencil hardness tester according to the JIS K5400 method under the following conditions: a load of 1 kg when a SUS pen presses on the adhesive protective film, an angle of 45° between the adhesive protective film surface and the SUS pen, a speed of 48 mm / min at which the SUS pen scratches the adhesive protective film, and a diameter of 1 mm when the SUS pen scratches the adhesive protective film.

[0039] The adhesive film has an initial peel strength of 1 gf / inch to 12 gf / inch, and the increase rate of the peel strength according to the following formula 1 is 180% or less:

[0040]

number

[0041] (In the above formula 1, P1 is the initial peel strength of the adhesive film (unit: gf / inch), P2 is the peel strength (unit: gf / inch) of the adhesive film after leaving the adhesive film at 50°C for 3 days and then at 25°C for 30 minutes. The "initial peel strength" means the peel strength measured before the adhesive film is left at 50°C for 3 days. Within this range of initial peel strength, the adhesive film is not easily separated from the adherend after adhering to the adherend, and therefore has a protective effect on the adherend, and the increase rate of the peel strength in Equation 1 may not be high. Within this range of increase rate of peel strength, even after the adhesive film is adhered to the adherend and left for a long period of time, damage and / or deformation of the adherend does not occur when the adhesive film is removed from the adherend, and process stability may be excellent.

[0042] Specifically, the initial peel force P1 may be, for example, 1 gf / inch, 1.5 gf / inch, 2 gf / inch, 2.5 gf / inch, 3 gf / inch, 3.5 gf / inch, 4 gf / inch, 4.5 gf / inch, 5 gf / inch, 5.5 gf / inch, 6 gf / inch, 6.5 gf / inch, 7 gf / inch, 7.5 gf / inch, 8 gf / inch, 8.5 gf / inch, 9 gf / inch, 9.5 gf / inch, 10 gf / inch, 10.5 gf / inch, 11 gf / inch, 11.5 gf / inch, 12 gf / inch, 1 gf / inch to 5 gf / inch, 2 gf / inch to 5 gf / inch, and more specifically, 2 gf / inch to 4.5 gf / inch. Specifically, the rate of increase in the peel force of Equation 1 may be, for example, 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 1% to 180%, or more specifically, 5% to 176%, 10% to 170%, 20% to 160%, 50% to 160%, 60% to 150%.

[0043] In one specific example, the adhesive film has a peel strength P2 after being left at 50°C for 3 days and then left at 25°C for 30 minutes that is equal to or greater than P1 and is 12 gf / inch or less, for example, 1 gf / inch, 1.5 gf / inch, 2 gf / inch, 2.5 gf / inch, 3 gf / inch, 3.5 gf / inch, 4 gf / inch, 4.5 gf / inch, 5 gf / inch, 5.5 gf / inch, 6 gf / inch, 6.5 gf / inch, 7 gf / inch, 7.5 gf / inch h, 8 gf / inch, 8.5 gf / inch, 9 gf / inch, 9.5 gf / inch, 10 gf / inch, 10.5 gf / inch, 11 gf / inch, 11.5 gf / inch, 12 gf / inch, 1 gf / inch to 12 gf / inch, 1 gf / inch to 9 gf / inch, 1 gf / inch to 8 gf / inch, 1 gf / inch to 7 gf / inch, 1 gf / inch to 6 gf / inch, 1 gf / inch to 5 gf / inch. Within the above range, the PSA film may have the effect of being removed without causing damage or deformation to the adherend even when peeled off after being left on the adherend for a long period of time.

[0044] The adhesive film may have a haze of 5% or less in the visible light region, specifically 0% to 2%, or 0% to 1%. In this range, the panel can be easily inspected for foreign matter after being adhered to the adherend, which may result in excellent processability.

[0045] The adhesive film may have a thickness of about 100 μm or less, for example, more than about 0 μm and not more than 75 μm. In this range, the adhesive film protects the adherend when adhered to the adherend, and can be easily peeled off from the adherend.

[0046] In order to provide a PSA film having the above-mentioned initial peel strength, rate of increase in peel strength, modulus and haze, the PSA film has a nitrogen (N) atom content of 0.5 to 1.50 wt % of the total atoms. Within this nitrogen (N) content range, the PSA film can satisfy all of the above-mentioned initial peel strength, rate of increase in peel strength, modulus and haze. For example, the adhesive film may have a nitrogen (N) atom content of 0.50 wt%, 0.55 wt%, 0.60 wt%, 0.65 wt%, 0.70 wt%, 0.75 wt%, 0.80 wt%, 0.85 wt%, 0.90 wt%, 0.95 wt%, 1.00 wt%, 1.05 wt%, 1.10 wt%, 1.15 wt%, 1.20 wt%, 1.25 wt%, 1.30 wt%, 1.35 wt%, 1.40 wt%, 1.45 wt%, or 1.50 wt%.

[0047] As will be described in detail below, the adhesive film is formed from a composition for adhesive film including a urethane-based binder and an isocyanate-based curing agent. The urethane-based binder contains a urethane bond having nitrogen (N) and a hydroxyl group (-OH), and the hydroxyl group reacts with the isocyanate-based curing agent. The isocyanate-based curing agent contains an isocyanate group (-NCO) having nitrogen (N). When the urethane-based binder is cured by the isocyanate-based curing agent, and the OH group of the urethane-based binder reacts with the NCO group of the isocyanate-based curing agent, a -NH(C=O)-O group is formed, so the nitrogen content does not change. Ultimately, the nitrogen (N) in the adhesive film originates from both the urethane-based binder and the isocyanate-based curing agent. In the present invention, the nitrogen (N) atom content in the total atoms in the PSA film is 0.5 wt% to 1.50 wt%, thereby simultaneously satisfying the above-mentioned initial peel force, peel force increase rate, modulus, and haze. In one embodiment, the nitrogen (N) atom content in the PSA film may be more than 0.6 wt% and 1.27 wt% or less. Preferably, the nitrogen (N) atom content in the total atoms in the PSA film may be 0.6 wt% to 1.27 wt%.

[0048] The "nitrogen content" in the adhesive film can be obtained by burning 2 mg of the adhesive film at 900° C. and subjecting the sample to elemental analysis using a gas chromatographic column.

[0049] In one specific example, nitrogen (N) may be present only in the urethane-based binder and the isocyanate-based curing agent, and nitrogen (N) may not be present in the remaining components of the adhesive film other than the urethane-based binder and the isocyanate-based curing agent.

[0050] The nitrogen (N) content in the PSA film can be achieved by controlling the type and / or content of each of the urethane binder and isocyanate curing agent contained in the PSA film composition. In one embodiment, the present invention can achieve the above-mentioned nitrogen (N) content in the PSA film by controlling the molar ratio [NCO] / [OH] in the composition to 0.7 to 1.2.

[0051] The "molar ratio [NCO] / [OH]" in the composition is the ratio of the total number of moles of isocyanate groups [NCO] of the isocyanate curing agent to the total number of moles of hydroxyl groups [OH] of the urethane binder in the composition. Preferably, the molar ratio [NCO] / [OH] may be 0.7, 0.74, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, specifically 0.7 or more and less than 1.15, more preferably 0.7 or more and 1.11 or less, and even more preferably 0.74 or more and 1.0 or less.

[0052] Hereinafter, a composition for a pressure-sensitive adhesive film according to one embodiment of the present invention will be described.

[0053] The composition for the pressure-sensitive adhesive film contains a urethane-based binder and an isocyanate-based curing agent.

[0054] The urethane-based binder may include a polyurethane polyol binder having a urethane bond and one or more hydroxyl groups (-OH). The urethane-based binder may have a weight 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, 150,000, specifically 60,000 to 120,000. Within the above range, the effects of the present invention can be easily realized.

[0055] In one embodiment, the urethane-based binder may include a unit derived from a polyether-based polyol. The unit derived from a polyether-based polyol may make it easier for the PSA film of the present invention to achieve the above-mentioned effects of the present invention.

[0056] In another embodiment, the urethane-based binder may include a unit derived from a polyether-based polyol and a unit derived from a polyester-based polyol. The unit derived from the polyester-based polyol may function to help the unit derived from the polyether-based polyol to easily realize the effects of the present invention.

[0057] In one embodiment, the urethane-based binder may be free of (meth)acrylate groups.

[0058] The polyurethane polyol binder may be prepared by reacting one or more polyols with one or more polyisocyanate compounds.

[0059] The polyol may include at least one of polyether-based polyols, polyester-based polyols, polyacrylic-based polyols, polycaprolactone-based polyols, and polycarbonate-based polyols. Preferably, the polyol may include at least one polyether-based polyol, and may further include at least one polyester-based polyol.

[0060] The polyether polyol may preferably be a polyether polyol having two or more hydroxyl groups, including a bifunctional polyether polyol (polyether diol) such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, or a trifunctional polyether polyol (polyether triol) of a glycerin alkylene oxide adduct. Through this, the urethane binder becomes a hyperbranched binder, and the effects of the present invention can be easily realized. The term "hyperbranched" refers to a polymer having many terminal functional groups and a dendritic branched structure.

[0061] The polyether polyol may have a number average molecular weight of 400 to 10,000, for example, 400, 1,000, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, specifically 1,000 to 7,000. In this range, it is possible to obtain an effect of obtaining a satisfactory peel force, wetting property, and modulus. Preferably, the polyether polyol includes a mixture of a polyether diol and a polyether triol, so that the effect of the present invention can be more easily realized.

[0062] The polyester-based polyol may include a polyol obtained by an esterification reaction between one or more polyols and one or more acid components. The polyol may include one or more 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, glycerin, trimethylolpropane, pentaerythritol, and hexanetriol. Examples of the acid component include 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, and acid anhydrides thereof.

[0063] The polyester polyol may include a polyester polyol having two or more hydroxyl groups, including at least one of a bifunctional polyester polyol (polyester diol) and a trifunctional polyester polyol (polyester triol). Through this, the urethane binder becomes a hyperbranched binder, and the effects of the present invention can be more easily realized.

[0064] The polyester polyol may have a number average molecular weight of 1000 to 5000, for example, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, specifically 2000 to 3000. Within this range, a satisfactory peel strength and modulus may be obtained, and an effect of suppressing an increase in the peel strength over time may be obtained.

[0065] The polyisocyanate compound may include a polyisocyanate compound having a plurality of isocyanate groups (-NCO). The polyisocyanate compound may be a known polyisocyanate compound, and may include one or more of aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate, and aromatic aliphatic polyisocyanate. Among them, aliphatic polyisocyanate may be preferred.

[0066] The aliphatic polyisocyanate compound may include one or more of 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.

[0067] In one embodiment, the urethane-based binder contains 0 mol% to 15 mol%, for example, 0 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, or 15 mol% of units derived from polyester-based polyols, and 15 mol% to 45 mol%, for example, 15 mol%, 16 mol%, or 17 mol% of units derived from polyether triols. , 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 27 mol%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, and 4 mol% to 44 mol% of units derived from polyether diol. mol%, for example, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 27 mol%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, %, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, and 35 mol% to 50 mol% of units derived from polyisocyanate-based compounds, for example, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, 46 mol%, 47 mol%, 48 mol%, 49 mol%, 50 mol%. In the above range, a satisfactory peel strength and modulus can be obtained, and an effect of suppressing an increase in the peel strength can be obtained.

[0068] The reaction may be carried out by adding a catalyst to a mixture containing one or more polyols and one or more polyisocyanate compounds, and then reacting them at a predetermined temperature. The ratio [NCO] / [OH] of the total number of moles of isocyanate groups (-NCO) in the polyisocyanate compounds to the total number of moles of hydroxyl groups (-OH) in the polyols of the mixture may be 0.5 to 0.96. Within this range, the nitrogen (N) content range in the pressure-sensitive adhesive film of the present invention may be easily reached. Preferably, [NCO] / [OH] may be 0.5 to 0.95, for example, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, for example, 0.5 to 0.9.

[0069] In one embodiment, one or more polyols in the mixture may include a polyether-based polyol. By including a polyether-based polyol as the polyol, the effects of the present invention can be more easily achieved.

[0070] In other embodiments, one or more polyols in the mixture can further include a polyester-based polyol. For example, the one or more polyols in the mixture may include 40 mol% to 65 mol%, e.g., 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, 46 mol%, 47 mol%, 48 mol%, 49 mol%, 50 mol%, 51 mol%, 52 mol%, 53 mol%, 54 mol%, 55 mol%, 56 mol%, 57 mol%, 58 mol%, 59 mol%, 60 mol%, 61 mol%, 62 mol%, 63 mol%, 64 mol%, 65 mol% of a polyether polyol, or 1 mol% to 15 mol%, e.g., 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol% of a polyester polyol. Within the above range, a satisfactory peel strength and modulus can be obtained, and an increase in the peel strength can be suppressed.

[0071] In one embodiment, the polyol may be free of polyester-based diols. In one embodiment, the polyol may be free of polyester-based triols.

[0072] The catalyst may include, but is not limited to, a tin-based compound such as dibutyltin dilaurate (DBTDL) or tin 2-ethylhexanoate.

[0073] The urethane binder is a polyol containing 40% by weight to 95% by weight of a triol, for example, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, 50% by weight, 51% by weight, 52% by weight, 53% by weight, 54% by weight, 55% by weight, 56% by weight, 57% by weight, 58% by weight, 59% by weight, 60% by weight, 61% by weight, 62% by weight, 63% by weight, 64% by weight, 65% by weight, 66% by weight, 67% by weight, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, 79% by weight, 80% by weight, 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88% by weight, 89% by weight, 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight, 96% by weight, 97% by weight, 98% by weight, 99% by weight, 99% by weight, 100% by weight, 102% by weight, 103% by weight, 104% by weight, 105% by weight, 106% by weight, 107% %, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, 79% by weight, 80% by weight, 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88% by weight, 89% by weight, 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight, and 5% to 60% by weight of diol, for example, 5%, 6%, 7% by weight, Amount%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, 41% by weight, 4 The polyol may be prepared from a polyol containing 2% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, 50% by weight, 51% by weight, 52% by weight, 53% by weight, 54% by weight, 55% by weight, 56% by weight, 57% by weight, 58% by weight, 59% by weight, 60% by weight, preferably a polyol containing more than 50% by weight and less than 95% by weight, 52% to 95% by weight, and a diol containing 5% by weight or more and less than 50% by weight, 5% to 48% by weight. In the above range, the hyperbranched urethane binder of the present invention can be easily prepared, and the effects of the present invention can be easily realized. The triol may include a polyether triol. The diol may include a polyether diol alone or a mixture of a polyether diol and a polyester diol.

[0074] In the production of a urethane-based binder, the triol is 40% by weight to 90% by weight of the total of the polyol and the isocyanate-based curing agent, for example, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, 50% by weight, 51% by weight, 52% by weight, 53% by weight, 54% by weight, 55% by weight, 56% by weight, 57% by weight, 58% by weight, 59% by weight, 60% by weight, 61% by weight, 62% by weight, 63% by weight, 64% by weight, 65% by weight, 66% by weight, 67% by weight, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, 79% by weight, 80% by weight, 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88% by weight, 89% by weight, 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight, 96% by weight, 97% by weight, 98% by weight, 99% by weight, 99% by weight, 100% by weight, 101% by weight, 102% by weight, 103% by weight, 1% by weight, 62% by weight, 63% by weight, 64% by weight, 65% by weight, 66% by weight, 67% by weight, 68% by weight, 69% by weight, 70% by weight, 71% by weight, 72% by weight, 73% by weight, 74% by weight, 75% by weight, 76% by weight, 77% by weight, 78% by weight, 79% by weight, 80% by weight, 81% by weight, 82% by weight, 83% by weight, 84% by weight, 85% by weight, 86% by weight, 87% by weight, 88% by weight, 89% by weight, 90% by weight, diol 2% to 50% % by weight, for example, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, 14% by weight, 15% by weight, 16% by weight, 17% by weight, 18% by weight, 19% by weight, 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight , 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, 50% by weight, and 2% to 10% by weight, for example, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, 7% by weight, 8% by weight, 9% by weight, 10% by weight, of an isocyanate-based curing agent. In the above range, the hyperbranched urethane-based binder of the present invention can be easily produced, and the effects of the present invention can be easily realized. The triol can include a polyether triol. The diol can include a polyether diol alone or a mixture of a polyether diol and a polyester diol.

[0075] The hyperbranched urethane binder may be prepared by placing a polyol mixture in a reactor, heating at 80°C to 100°C for 10 to 30 minutes under nitrogen purging to completely remove residual moisture, lowering the internal temperature of the reactor to 60°C to 70°C, adding a polyisocyanate compound and a catalyst, and performing primary polymerization at 60°C to 75°C for 2 to 4 hours, and then performing secondary polymerization at 75°C to 85°C for 60 to 120 minutes.

[0076] The isocyanate-based curing agent provides a matrix for the adhesive film by reacting the isocyanate group with the hydroxyl group of the urethane-based binder, and can provide the peeling force of the adhesive film.

[0077] The isocyanate-based curing agent may include a typical isocyanate-based curing agent known to those skilled in the art as a polyfunctional isocyanate-based curing agent having a plurality of isocyanate groups (-NCO).

[0078] In one embodiment, the isocyanate-based curing agent may include one or more of aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and araliphatic polyisocyanates, or their polyol adducts, their biuret forms, or their isocyanurates. For example, the aliphatic polyisocyanate-based compound may include one or more of 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. Preferably, the isocyanate-based curing agent may include an isocyanurate form of the above-mentioned isocyanate-based curing agent.

[0079] The isocyanate-based curing agent may be included in an amount of 2 to 10 parts by weight, for example, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, specifically 4 parts by weight to 7 parts by weight, based on 100 parts by weight of the urethane-based binder. Within this range, there may be an effect of obtaining satisfactory physical properties after curing.

[0080] The composition may further comprise a crosslinking catalyst.

[0081] The crosslinking catalyst can catalyze the reaction between the urethane binder and the isocyanate curing agent. The crosslinking catalyst can include one or more metal-based catalysts. The metal-based catalyst can include one or more tin-based catalysts and non-tin-based catalysts. The tin-based catalyst and non-tin-based catalyst can be of any type known to those skilled in the art. For example, the tin-based catalyst can include, but is not limited to, dibutyltin dichloride, dibutyltin oxide, dibutyltin dilaurate, dibutyltin sulfide, dibutyltin diacetate, dibutyltin maleate, etc.

[0082] The crosslinking catalyst may be included in an amount of 0.005 to 0.5 parts by weight, specifically 0.01 to 0.1 parts by weight, based on 100 parts by weight of the urethane binder. Within this range, a satisfactory pot life and fast curing can be obtained.

[0083] The composition may further comprise a leveling agent.

[0084] The leveling agent can improve the leveling property of the PSA film. The leveling agent can include an acrylic leveling agent, a fluorine-based leveling agent, a silicone-based leveling agent, a silicone-acrylate leveling agent, and the like.

[0085] The leveling agent may be included in an amount of 0.1 to 5 parts by weight, specifically 0.3 to 1 part by weight, based on 100 parts by weight of the urethane binder. Within this range, it is possible to obtain an effect of obtaining a low initial peel strength.

[0086] The composition may further comprise a plasticizer.

[0087] The plasticizer must provide a low initial peel strength for the adhesive film of the present invention, yet can enhance shatter resistance by lowering the modulus of the adhesive film.

[0088] Examples of the plasticizer include esters of monobasic or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms, esters of unsaturated fatty acids or branched acids having 14 to 18 carbon atoms and tetrahydric or less alcohols, and esters of monobasic or polybasic acids having 6 to 10 carbon atoms and polyalkylene glycols. Examples of the plasticizer include, but are not limited to, isopropyl myristate, isopropyl palmitate, isostearyl palmitate, isostearyl laurate, diisostearyl adipate, diisocetyl sebacate, etc.

[0089] The plasticizer may be included in an amount of 1 to 30 parts by weight, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 parts by weight, specifically 10 to 30 parts by weight, based on 100 parts by weight of the urethane binder. Within this range, it may be effective in obtaining a low initial peel strength and a low modulus.

[0090] The composition may further include additives, which may include, but are not limited to, antistatic agents, UV absorbers, UV stabilizers, antioxidants, heat stabilizers, surfactants, and the like.

[0091] The adhesive film can be produced by applying the adhesive film composition to a predetermined thickness on a substrate film, drying the composition at 110°C to 140°C, and then aging the composition at 30°C to 70°C for 1 to 3 days, but is not limited thereto.

[0092] An optical component according to one embodiment of the present invention includes an optical film and an adhesive film for a surface protective film formed on at least one surface of the optical film, and the adhesive film for a surface protective film includes an adhesive film for a surface protective film according to each embodiment of the present invention.

[0093] 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 element layer and a polyimide film formed on at least one surface of the light emitting element layer. An organic insulating film or an inorganic insulating film 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 silicone-based adhesive protective film. The release film may prevent the adhesive protective film from being contaminated by external foreign matter. As the release film, an optical film formed of the same or different material as the optical film described above may be used. For example, the release film may be a film formed of one or more resins selected from polyethylene terephthalate resin, polycarbonate resin, polyimide resin, poly(meth)acrylate resin, cyclic olefin polymer resin, and acrylic resin. The release film may have a thickness of 10 μm to 100 μm, preferably 10 μm to 50 μm. The adhesive protective film may be supported within the above range.

[0094] [Mode for carrying out the invention] The present invention will be described in more detail with reference to the following examples, which are provided only to facilitate understanding of the present invention and are not intended to limit the scope of the present invention.

[0095] Manufacturing Example 1: Manufacturing of urethane binder The polyether polyol was added to a 1000 mL jacket reactor in the weights shown in Table 1 below, and then mixed under nitrogen purging. Toluene was then added to the resulting mixture, which was stirred for 10 minutes and heated to 85°C for 30 minutes under nitrogen purging to remove residual moisture. The internal temperature of the reactor was then lowered to 60°C, and hexamethylene diisocyanate (HDI) was added in the weights shown in Table 1 below. This was further stirred at 60°C for 10 minutes, and then the polymerization catalyst dibutyltin dilaurate (DBTDL) was added. After 1 hour, the internal temperature of the reactor was raised to 70°C, and then raised again to 80°C after 1 hour, and polymerization reaction was carried out at 80°C for 2 hours. The binder solution obtained from the result was then diluted with toluene to prepare a solution with a solid content of 65% by weight, which was then cooled to room temperature to obtain a solid content. The solid content contains a hyperbranched urethane binder having multiple hydroxyl groups (-OH).

[0096] Production Examples 2 to 14: Production of urethane binders A hyperbranched urethane binder was prepared in the same manner as in Preparation Example 1, except that the types and weights of the polyether polyol and polyester polyol, and the weight of hexamethylene diisocyanate in Preparation Example 1 were changed as shown in Table 1 below.

[0097] In Table 1 below, "-" means that the corresponding ingredient is not included.

[0098] When producing the urethane binder, the ratio [NCO] / [OH] of the total number of moles of isocyanate groups (-NCO) in hexamethylene diisocyanate, which is a polyisocyanate, to the total number of moles of hydroxyl groups (-OH) in polyols including polyether polyols and polyester polyols was calculated, and the results are shown in Table 1 below.

[0099] The weight average molecular weight (Mw) of the urethane binder was measured using GPC, and the results are shown in Table 1 below.

[0100] [Table 1]

[0101] In Table 1, I: Polyether-based diols - Diol 1: PPG-1000D; Diol 2: PPG-2000D; Diol 3: PPG-3000D (all from Kumho Petrochemical, Korea); II: Polyether triols - Triol 1: PPG-3020; Triol 2: PPG-7000 (Kumho Petrochemical, Korea) III: Polyester diol (Polyol P-2010, Kuraray) IV: Polyester triol (Polyol F-2010, Kuraray) Example 1 A composition for adhesive film was prepared by mixing 100 parts by weight of the urethane binder prepared in Preparation Example 1, an isocyanate curing agent (Coronate HX), 4.5 parts by weight of an isocyanurate adduct of hexamethylene diisocyanate, 0.01 parts by weight of a crosslinking catalyst dibutyltin dilaurate (DBTDL), 0.30 parts by weight of a leveling agent (BYK-3700, BYK, silicone-acrylate system), and 15 parts by weight of a plasticizer isopropyl myristate, based on the solid content.

[0102] The prepared adhesive film composition was applied to the upper surface of a base film (PET film, thickness: 75 μm) in a predetermined thickness using an applicator and dried for 4 minutes at 130° C. Then, the obtained coating layer was covered with a release film (PET film, thickness: 25 μm, antistatic coating layer was formed) and aged at 50° C. for 2 days to prepare an adhesive sheet laminated in the order of base film-adhesive film for surface protection film (thickness: 75 μm)-release film.

[0103] Examples 2 to 14 Except for changing the content of one or more of the urethane binder type, curing agent, crosslinking catalyst, leveling agent, and plasticizer as shown in Table 2 below (unit: weight part), an adhesive sheet having a base film-adhesive film for surface protection film (thickness: 75 μm)-release film laminated in this order was prepared in the same manner as in Example 1.

[0104] Comparative Examples 1 to 6 Except for changing the content of one or more of the urethane binder type, curing agent, crosslinking catalyst, leveling agent, and plasticizer as shown in Table 2 below (unit: weight part), an adhesive sheet having a base film-adhesive film for surface protection film (thickness: 75 μm)-release film laminated in this order was prepared in the same manner as in Example 1.

[0105] Comparative Example 7 A polyol blend was prepared by mixing 13.5 moles of polyether-based diol PPG-1000D, 29.2 moles of polyether-based triol PPG-3020, and 57.3 moles of polyether-based triol PPG-10000.

[0106] Based on the solid content, a composition was prepared by adding at least one of the curing agent, crosslinking catalyst, leveling agent, and plasticizer to 100 parts by weight of the prepared polyol blend in an amount as shown in Table 2 (unit: parts by weight) below, and an adhesive sheet having a base film-adhesive film for surface protection film (thickness: 75 μm)-release film laminated in this order was prepared in the same manner as in Example 1. The composition of Comparative Example 7 did not contain a urethane-based binder.

[0107] Comparative Example 8 Except for changing the content of the curing agent in Comparative Example 7 as shown in Table 2 below, the same method as in Comparative Example 7 was carried out to prepare an adhesive sheet having a base film, an adhesive film for surface protection film (thickness: 75 μm), and a release film laminated in that order. The composition of Comparative Example 8 does not contain a urethane-based binder.

[0108] The adhesive film compositions for surface protective films and / or adhesive films for surface protective films prepared in the Examples and Comparative Examples were evaluated for the following physical properties, and the results are shown in Table 3 below.

[0109] (1) [NCO] / [OH]: The ratio of the total number of moles of the isocyanate group [NCO] of the isocyanate curing agent to the total number of moles of the hydroxyl group [OH] of the urethane binder in the adhesive film composition produced in the examples and comparative examples was calculated. The number of moles of [OH] was calculated using the [OH] moles functional group number calculation method. The number of moles of [NCO] was calculated using the [NCO] moles functional group number calculation method.

[0110] (2) Initial peel strength (P1) (unit: gf / inch): The adhesive sheets produced in the examples and comparative examples were cut to width x length (25 mm x 200 mm), and the release PET film was removed to expose the adhesive film in the adhesive sheet. A glass plate, which was the adherend, was placed on the surface of the exposed adhesive film, and pressure was applied with a 2 kg roller to produce a test specimen laminated in the order of glass plate - adhesive film - base film.

[0111] Thirty minutes after the preparation of the test specimen, the peel strength was measured by using a TA (Texture analyzer), which is a peel strength measuring device, when the PSA film was peeled off from the glass plate at a peel speed of 2400 mm / min, a peel angle of 180°, and a peel temperature of 25° C. The peel strength was measured three times and then averaged.

[0112] (3) Peel strength (P2) after 3 days at 50°C (unit: gf / inch): A test specimen was prepared by laminating a glass plate, adhesive film and base film in this order in the same manner as in (2).

[0113] The prepared test piece was placed in an oven at 50° C. for 3 days. After that, the test piece was removed from the oven and placed at 25° C. for 30 minutes. After that, the peel force was measured in the same manner as in (2).

[0114] (4) Increase rate of peel force (unit: %): Using the peel forces obtained in (2) and (3), the increase rate of peel force was calculated using Equation 1.

[0115] (5) Haze (unit: %): After the base film and release film were peeled off from the pressure-sensitive adhesive sheets of the examples and comparative examples to obtain pressure-sensitive adhesive films, test pieces were produced by adhering the pressure-sensitive adhesive films to glass plates. The haze of the produced test pieces was measured in the visible light range using a haze measuring device, NDH-9000. If the haze was 2% or less, it was evaluated as "○", if it was more than 2% and less than 3%, it was evaluated as "△", and if it was more than 3%, it was evaluated as "X".

[0116] (6) Modulus (unit: MPa): A composition for adhesive film of the Examples and Comparative Examples was coated to a predetermined thickness on one side of a fluorine-treated film (Dongwon Intech, FL-75BML), and a PET film was laminated on the coating layer, and then the laminate was dried at 130° C. for 4 minutes and aged at 50° C. for 2 days to prepare a laminate in which an adhesive protective film of 75 μm in thickness was laminated between the fluorine-treated film and the PET film. The laminate was cut into the shape of a dog bone as shown in FIG. 1, and the fluorine-treated film and the PET film were removed to prepare a test piece for modulus measurement.

[0117] Referring to FIG. 1, the test specimen had a dogbone shape with an overall length of 40 mm, an overall width of 15 mm, and a thickness of 75 μm.

[0118] The modulus was measured using a modulus measuring device (Instron) for the manufactured modulus measuring test piece. Specifically, the left end of the dog bone in FIG. 1 was connected to the first jig of the modulus measuring device, and the right end was connected to the second jig of the modulus measuring device. At this time, the part of the left end connected to the first jig and the part of the right end connected to the second jig were made to have the same area. Then, with the first jig fixed, the second jig was pulled at a load cell of 1 kN, a pulling speed of 50 mm / min, and 25° C., and the value at which the part of the dog bone in FIG. 1 marked as 15 mm wide and 5 mm thick broke was obtained as the modulus.

[0119] (7) Nitrogen (N) content (unit: weight %): The base film and release film were all removed from the adhesive sheets manufactured in the examples and comparative examples, and 2 mg of adhesive film was taken from them. 2 mg of adhesive film was placed in a gas chromatograph and burned at 900°C for several seconds, and then quantitative elemental analysis was performed by gas chromatograph to obtain the ratio of nitrogen (N) atom content in the total atoms of the adhesive film.

[0120] [Table 2]

[0121] [Table 3]

[0122] As shown in Table 3, the pressure-sensitive adhesive film for surface protection film of the present invention satisfied all of the initial peel strength and the increase rate of peel strength in Equation 1 of the present invention. As a result, the pressure-sensitive adhesive film of the present invention simultaneously provided a temporary protective effect for the adherend and an effect of being removed from the adherend without deformation and / or damage to the adherend. Thus, although not shown in Table 3, the pressure-sensitive adhesive film of the present invention provides a protective effect for the adherend by being laminated on the adherend, and can be removed without deformation and / or damage to the adherend when peeled off from the adherend after adhering to the adherend for a long period of time.

[0123] In addition, the adhesive film for surface protection film of the present invention satisfied all of the ranges of the modulus at 25°C and the nitrogen atom content in the total atoms of the adhesive film of the present invention. Therefore, although not shown in Table 3, it can provide good wetting properties, shatterproof properties, cuttability and processability.

[0124] Furthermore, the pressure-sensitive adhesive film for surface protection films of the present invention had low haze and was therefore excellent in cuttability and processability.

[0125] On the other hand, the pressure-sensitive adhesive films of the comparative examples cannot provide all of the above-mentioned effects of the pressure-sensitive adhesive film of the present invention.

[0126] Simple modifications and variations of the present invention can be easily implemented by those having ordinary skill in the art, and all such modifications and variations can be considered to be included within the scope of the present invention.

Claims

1. An adhesive film for a surface protective film, which is formed from a composition for an adhesive film containing a urethane-based binder and an isocyanate-based curing agent, a ratio of the total number of moles of isocyanate groups of the isocyanate-based curing agent to the total number of moles of hydroxyl groups of the urethane-based binder contained in the composition for pressure-sensitive adhesive film is 0.7 to 0.95; The adhesive film has an increase in peel strength of 180% or less as determined by the following formula 1: [0010] (In the above formula 1, P1 is the initial peel strength of the adhesive film (unit: gf / inch (2.54 cm)); P2 is the peel strength (unit: gf / inch (2.54 cm)) of the adhesive film after leaving the adhesive film at 50° C. for 3 days and then leaving the adhesive film at 25° C. for 30 minutes; The adhesive film has an initial peel strength of 1 gf / inch (2.54 cm) to 12 gf / inch (2.54 cm); The adhesive film has a nitrogen (N) atom content of 0.5 wt % to 1.50 wt % of the total atoms, The pressure-sensitive adhesive film has a modulus at 25° C. of 0.05 MPa to 0.8 MPa and satisfies at least one of the following (i) and (ii): (i) The adhesive film has a haze of 5% or less in the visible light region; (ii) The pressure-sensitive adhesive film has a peel strength of 12 gf / inch (2.54 cm) or less after being left at 50° C. for 3 days and then at 25° C. for 30 minutes.

2. The adhesive film for surface protective films according to claim 1 , wherein the urethane-based binder contains a unit derived from a polyether-based polyol.

3. The adhesive film for surface protective films according to claim 2 , wherein the urethane-based binder further contains a unit derived from a polyester-based polyol.

4. The adhesive film for surface protective films according to claim 1 , wherein the urethane-based binder is hyperbranched.

5. The adhesive film for surface protective films according to claim 1 , wherein the urethane-based binder is made from a polyol containing 40% by weight to 95% by weight of a triol and 5% by weight to 60% by weight of a diol.

6. The adhesive film for surface protective films according to claim 1 , wherein the isocyanate-based curing agent comprises an isocyanurate of an aliphatic polyisocyanate-based, alicyclic polyisocyanate-based, aromatic polyisocyanate-based, or araliphatic polyisocyanate-based curing agent.

7. The adhesive film for surface protection film according to claim 1 , wherein the isocyanate-based hardener is contained in an amount of 2 to 10 parts by weight based on 100 parts by weight of the urethane-based binder.

8. The adhesive film for surface protective films according to claim 1 , wherein the composition further comprises at least one of a crosslinking catalyst, a plasticizer, and a leveling agent.

9. The adhesive film for surface protective films described in claim 8, wherein the plasticizer comprises one or more of esters of monobasic acids or polybasic acids having 6 to 18 carbon atoms and branched alcohols having 18 or less carbon atoms, esters of unsaturated fatty acids or branched acids having 14 to 18 carbon atoms and alcohols having 4 or less hydricities, and esters of monobasic acids or polybasic acids having 6 to 10 carbon atoms and polyalkylene glycols.

10. The adhesive film has an increase rate of the peel force of 170% or less, The adhesive film for surface protection film according to claim 1 , wherein the adhesive film has a nitrogen (N) atom content of 0.65 to 1.50 wt % of the total atoms.

11. Optical films; and An optical member comprising the adhesive film for surface protection film according to claim 1 formed on at least one surface of the optical film.

Images