KR102408413B1 - Adhesive composition and protective film using same - Google Patents

Abstract

The present invention relates to a pressure-sensitive adhesive composition and a protective film using the same, wherein the pressure-sensitive adhesive composition comprising an antistatic agent containing two or more ionic liquids has excellent optical properties, wettability and adhesive strength, and is free from static electricity during peeling and peeling electrification voltage It is possible to provide a protective film that is low, has a low degree of surface contamination of the adherend, and has little change in physical properties, such as the adhesive strength of the adhesive layer over time.
Therefore, the protective film using the pressure-sensitive adhesive composition may be usefully used during the display panel manufacturing process.

Description

Adhesive composition and protective film using same {ADHESIVE COMPOSITION AND PROTECTIVE FILM USING SAME}

The present invention relates to a pressure-sensitive adhesive composition and a protective film using the same.

Various protective films are used during the manufacturing process of display panels.

Specifically, in the process of turning the panel over or attaching various chips to the back side, a protective film is attached to absorb the impact applied to the front of the panel and prevent scratches or contamination by the conveyor. Physical properties required for a protective film vary depending on the type.

For example, a display panel made of glass or plastic material is weak to impact, so it has a thickness enough to absorb the impact applied during the process and a protection with an adhesive function that can effectively follow the steps created by various printing patterns or shapes. A film is required, and the required properties of the protective film are as follows:

First, it must have excellent adhesion (wettability) with respect to the step (irregularity) of the surface of the adherend to be adhered, and stability of the lamination is required so that it does not float on the surface over time. Second, in the stage where the process is completed and the protective film is removed, there should be no foreign matter generated by the pressure-sensitive adhesive being transferred to the adherend or scattering of the pressure-sensitive adhesive. Third, when removing (peeling) the protective film from the adherend, the peeling electrification voltage should be low.

In order to satisfy these requirements, a method of forming a separate antistatic layer on the surface of the adhesive layer of the protective film has been studied, but there are disadvantages in that additional time and cost occur and the process becomes complicated.

Accordingly, a method of adding an antistatic agent to the inside of the adhesive layer is mainly used. However, in order to satisfy the above requirements, it is necessary to use a large amount of antistatic agent. In this case, the antistatic agent is not completely dissociated into the pressure-sensitive adhesive composition, which may make the pressure-sensitive adhesive layer opaque, and even if the pressure-sensitive adhesive layer is transparent, an excess of antistatic agent is used in the pressure-sensitive adhesive layer. There is a problem in that it migrates to the surface and causes contamination that leaves stains on the surface of the adherend (panel or optical film), or that physical properties such as adhesive strength change over time.

Korean Publication No. 2002-0091198

Therefore, an object of the present invention is to have excellent physical properties such as optical properties, wettability and adhesion, low static electricity and peeling electrification voltage during peeling, low surface contamination of the adherend, and change in physical properties of the adhesive layer over time It is to provide a pressure-sensitive adhesive composition capable of providing a small amount of a protective film, and a protective film derived therefrom.

In order to achieve the above object, the present invention provides a pressure-sensitive adhesive composition comprising a polyurethane-based resin, a diisocyanate-based curing agent and an antistatic agent, wherein the antistatic agent includes two or more ionic liquids.

In order to achieve the above other object, the present invention is a first base layer; and an adhesive layer formed on the first base layer and derived from the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition according to an embodiment of the present invention contains an antistatic agent comprising two or more ionic liquids, and thus has excellent optical properties, wettability and adhesion when applied to a protective film, and has low electrostatic phenomenon and peeling electrification voltage during peeling In addition, it is possible to provide a protective film with low surface contamination of the adherend and with little change in physical properties such as adhesion over time.

1 is a schematic diagram of a protective film according to an embodiment of the present invention.
2 is a schematic diagram of a protective film according to another embodiment of the present invention.

The present invention is not limited to the contents disclosed below, and may be modified in various forms as long as the gist of the present invention is not changed.

The terminology used herein is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise.

In this specification, a component described as being formed above or below another component means that a component is formed directly above or below another component or indirectly through another component. include

In addition, the reference for the upper / lower of each component will be described with reference to the drawings. The size of each component in the drawings may be exaggerated for explanation, and may be different from the size actually applied.

In the present specification, "comprising" means that other components may be further included unless otherwise specified. In addition, it should be understood that all numbers and expressions indicating amounts of components, reaction conditions, etc. described herein are modified by the term "about" in all cases unless otherwise specified.

adhesive composition

The pressure-sensitive adhesive composition according to an embodiment of the present invention includes a polyurethane-based resin, a diisocyanate-based curing agent, and an antistatic agent, and the antistatic agent includes two or more ionic liquids.

The ionic liquid means a salt that becomes a liquid at room temperature, and is composed of a cation and an anion. The ionic liquid has an advantage of having low viscosity, excellent heat resistance and high ionic conductivity.

The pressure-sensitive adhesive composition according to an embodiment of the present invention contains two or more ionic liquids as an antistatic agent, and thus has excellent optical properties, wettability and adhesion even with a small amount of antistatic agent, has a low peeling electrification voltage, It is possible to provide a protective film having a low surface contamination level and less change in physical properties such as adhesion over time.

The at least two ionic liquids include a first ionic liquid containing a hydrophilic anion and a second ionic liquid containing a hydrophobic anion.

The first ionic liquid may include an ionic liquid having good compatibility with the polyurethane-based resin and including a hydrophilic anion exhibiting polarity. In addition, the second ionic liquid may include an ionic liquid containing a hydrophobic anion exhibiting a non-polarity, which is relatively poor in compatibility with the polyurethane-based resin. In this case, the "compatibility" may be determined by the polarity difference between the ionic liquid (the first ionic liquid or the second ionic liquid) and the polyurethane-based resin.

According to the embodiment of the present invention, when using a mixture of the two or more types of ionic liquids, due to the use of the first ionic liquid having relatively good compatibility with the polyurethane resin, proper miscibility with the polyurethane resin It is possible to lower the surface contamination of the adherend when transferring to the surface of the pressure-sensitive adhesive layer, and it is efficient even with a small amount of antistatic agent due to the use of a second ionic liquid having relatively poor compatibility with the polyurethane resin can lower the peeling electrification voltage. In particular, when the two or more types of ionic liquids are properly combined and used, changes in physical properties such as adhesion over time can be minimized even with a small amount of antistatic agent, and the effect of reducing the peeling electrification voltage can be maximized. have.

The hydrophilic anion is selected from the group consisting of a chloride anion (Cl ^- ), a bromide anion (Br ^- ), an iodide anion (I ^- ), a nitrate anion (NO ₃ ^- ) and an acetate anion (CH ₃ CO ₂ ^- ) It may include one or more of the Specifically, the hydrophilic anion is at least one selected from the group consisting of a bromide anion (Br ^- ), an iodide anion (I ^- ), a nitrate anion (NO ₃ ^- ), and an acetate anion (CH ₃ CO ₂ ^- ) may include

The hydrophobic anion is a hexafluorophosphate anion (PF ₆ ^- ), a tetrafluoroborate anion (BF ₄ ^- ), a bis((trifluoromethyl)sulfonyl)imide anion (TFSI ^- ) and trifluoromethanesulfo It may include at least one selected from the group consisting of an anion of nate (TF ^- ). Specifically, the hydrophobic anion may include at least one selected from the group consisting of a hexafluorophosphate anion (PF ₆ ⁻ ) and a tetrafluoroborate anion (BF ₄ ⁻ ).

The first ionic liquid and the second ionic liquid are each an alkylimidazolium cation, a dialkylimidazolium cation, a trialkylimidazolium cation, a tetraalkylimidazolium cation, an alkylpyridinium cation, and a dialkylpyri Containing at least one cation selected from the group consisting of dinium cation, dialkylpiperidinium cation, alkylpyrimidinium cation, alkylpyrazolium cation, sulfonium cation, alkylpinolidinium cation, alkylammonium cation and alkylphosphonium cation can do.

Specifically, the cation included in the first ionic liquid and the second ionic liquid may include at least one selected from the group consisting of an alkylimidazolium cation, a dialkylimidazolium cation, and an alkylammonium cation. can

The cation may be selected irrespective of the type of the hydrophilic anion and the hydrophobic anion, and may be combined with the hydrophilic anion and the hydrophobic anion to constitute the first ionic liquid and the second ionic liquid.

For example, the first ionic liquid may include an alkylammonium cation and a nitrate anion (NO ₃ ⁻ ). Alternatively, the first ionic liquid may include an alkylammonium cation and an acetate anion (CH ₃ CO ₂ ⁻ ). Alternatively, the first ionic liquid may include an alkylimidazolium cation and an acetate anion (CH ₃ CO ₂ ⁻ ). Alternatively, the first ionic liquid may include an alkylimidazolium cation and a nitrate anion (NO ₃ ⁻ ).

The second ionic liquid may include an alkylimidazolium cation and a hexafluorophosphate anion (PF ₆ ⁻ ). Alternatively, the second ionic liquid may include a dialkylimidazolium cation and a hexafluorophosphate anion (PF ₆ ⁻ ). Alternatively, the second ionic liquid may include an alkylammonium cation and a hexafluorophosphate anion (PF ₆ ⁻ ). Alternatively, the second ionic liquid may include an alkylimidazolium cation and a tetrafluoroborate anion (BF ₄ ⁻ ).

According to an embodiment of the present invention, the first ionic liquid and/or the second ionic liquid may not contain metal ions. If the first ionic liquid and / or the second ionic liquid contains a metal ion, for example, a metal cation, the metal cation that has not been combined with the polyurethane-based resin may cause crystallization while bonding with the anion, The metal salt may cause scattering, which may make the coating layer cloudy or increase the surface contamination level of the adherend.

On the other hand, in terms of improving the physical properties of the pressure-sensitive adhesive composition and the protective film using the same, the content of the first ionic liquid and the second ionic liquid may be important.

According to an embodiment of the present invention, the weight ratio of the first ionic liquid and the second ionic liquid may be 1: 0.1 to 2.0. Specifically, the weight ratio of the first ionic liquid and the second ionic liquid may be 1:0.6 to 1.2, 1:0.6 to 1.0, or 1:0.8 to 1.0. When within the above range, it is possible to minimize the change in physical properties such as adhesive force over time even with a small amount of the antistatic agent, and it is possible to maximize the effect of reducing the peeling electrification voltage.

In addition, the antistatic agent comprising the first ionic liquid and the second ionic liquid is 0.2 to 6 parts by weight, 0.4 to 5 parts by weight, 0.4 to 4 parts by weight, 0.4 to 3 parts by weight based on 100 parts by weight of the polyurethane-based resin. parts, or 1 to 3 parts by weight. If the content of the antistatic agent exceeds the above range, haze may increase and use as a protective film requiring transparency may be limited.

The first ionic liquid may be included in an amount of 0.1 to 3 parts by weight, 0.2 to 2 parts by weight, 0.2 to 1.8 parts by weight, 0.2 to 1.5 parts by weight, or 0.5 to 1.5 parts by weight based on 100 parts by weight of the polyurethane-based resin. . When it is within the above range, it has appropriate miscibility with the polyurethane-based resin, and can lower the degree of surface contamination of the adherend when transferred to the surface of the adhesive layer.

The second ionic liquid may be included in an amount of 0.1 to 3 parts by weight, 0.2 to 2 parts by weight, 0.2 to 1.8 parts by weight, 0.2 to 1.5 parts by weight, or 0.5 to 1.5 parts by weight based on 100 parts by weight of the polyurethane-based resin. . When it is within the above range, the peeling electrification voltage can be effectively lowered even with a small amount of the antistatic agent.

Meanwhile, the polyurethane-based resin may be prepared by reacting a polyol with an isocyanate compound.

The isocyanate compound used in the preparation of the polyurethane-based resin may be one selected from the group consisting of aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, and combinations thereof.

The isocyanate compound is, for example, 2,4-toluene diisocyanate (2,4-toluene diisocyanate, 2,4-TDI), 2,6-toluene diisocyanate (2,6-toluene diisocyanate, 2,6- TDI) naphthalene-1,5-diisocyanate, p-phenylene diisocyanate, tolidine diisocyanate, 4,4'-diphenyl methane selected from the group consisting of 4,4'-diphenyl methane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and combinations thereof may contain one.

The polyol is a compound containing at least two or more hydroxyl groups (-OH) per molecule, for example, polyether polyol, polyester polyol, polycarbonate polyol, It may include one selected from the group consisting of acrylic polyols and combinations thereof.

The polyol is, for example, polytetramethylene ether glycol, polypropylene ether glycol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 2-methyl -1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol , may include one selected from the group consisting of tripropylene glycol and combinations thereof.

The polyol may have a weight average molecular weight (Mw) of about 100 g/mol to about 3,000 g/mol. The polyol may have a weight average of, for example, from about 100 g/mol to about 3,000 g/mol, such as from about 100 g/mol to about 2,000 g/mol, such as from about 100 g/mol to about 1,800 g/mol. It may have a molecular weight (Mw).

In one embodiment, the polyol is a low molecular weight polyol having a weight average molecular weight (Mw) of about 100 g/mol or more and less than about 300 g/mol, and a high molecular weight having a weight average molecular weight (Mw) of about 300 g/mol or more and about 1800 g/mol or less polyols.

The polyurethane-based resin may have a weight average molecular weight (Mw) of about 500 g/mol to about 3,000 g/mol. The polyurethane-based resin may have a weight average molecular weight (Mw) of, for example, about 1,000 g/mol to about 2,000 g/mol, for example, about 1,000 g/mol to about 1,500 g/mol.

Meanwhile, the diisocyanate-based curing agent may be an aliphatic isocyanate compound including two or more functional groups, an alicyclic isocyanate compound, an aromatic isocyanate compound, and the like.

Specifically, the diisocyanate-based curing agent is toluene diisocyanate, methylenediphenyl diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate trimer, toluene diisocyanate trimer, isophorone di isocyanate trimers or mixtures thereof. More specifically, it may be a hexamethylene diisocyanate trimer or an isophorone diisocyanate trimer.

The hexamethylene diisocyanate trimer is more advantageous in terms of securing the flexibility of the adhesive layer, and the isophorone diisocyanate trimer is advantageous in forming a hard film although the reaction rate is slow.

The diisocyanate-based curing agent may be included in an amount of 1 to 10 parts by weight, 3 to 10 parts by weight, 3 to 8 parts by weight, or 3 to 5 parts by weight based on 100 parts by weight of the polyurethane-based resin. When within the above range, it is possible to provide an adhesive layer having an appropriate initial adhesive force.

Meanwhile, the pressure-sensitive adhesive composition according to another embodiment of the present invention includes a polyurethane-based resin, a diisocyanate-based curing agent, and an antistatic agent, and may further include a slip agent, a catalyst, and the like, if necessary.

The slip agent imparts a sliding property (slip property) to the pressure-sensitive adhesive composition.

The slip agent may be obtained through a combination of at least one selected from the group consisting of an organic modified polydimethylsiloxane-based compound, a fluorine-modified polyacrylate-based compound, and a perfluoropolyether (PFPE)-based compound.

The slip agent may be a polydimethylsiloxane-based compound including a hydroxy functional group. The polydimethylsiloxane-based compound including the hydroxy functional group may have a weight average molecular weight of 1,000 to 50,000 g/mol or 10,000 to 50,000 g/mol.

The polydimethylsiloxane-based compound including the hydroxy functional group may be transferred to the surface of the adherend by bonding with the acrylic copolymer to which the vinyl group-containing monomer is addition bonded, thereby suppressing deterioration of surface properties of the adherend.

The slip agent may be included in an amount of 0.1 to 10 parts by weight, 0.1 to 7 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, or 0.1 to 1.5 parts by weight based on 100 parts by weight of the polyurethane-based resin. When within the above range, it is possible to provide an adhesive layer having excellent adhesive strength.

The catalyst serves as an accelerator to accelerate the reaction. The catalyst may include a tin-based catalyst, specifically 1 selected from the group consisting of stannous octoate, dibutyltin dilaurate, and dioctyltin dilaurate It may include more than one species.

The catalyst may be included in an amount of 0.1 to 5 parts by weight, 0.1 to 3 parts by weight, 0.1 to 2.5 parts by weight, or 0.2 to 2 parts by weight based on 100 parts by weight of the polyurethane-based resin. When within the above range, it is possible to provide an adhesive layer having excellent adhesive strength.

In addition, the pressure-sensitive adhesive composition may further include various additives commonly used as long as the desired effect of the present invention is not impaired.

protective film

Another embodiment of the present invention provides a protective film comprising an adhesive layer derived from the pressure-sensitive adhesive composition.

Referring to FIG. 1 , a protective film 1 according to an embodiment of the present invention includes a first base layer 11 ; and an adhesive layer 12 formed on the first base layer 11 and derived from the pressure-sensitive adhesive composition.

Hereinafter, each layer of the protective film will be described in detail.

first base layer

The protective film according to the embodiment of the present invention may include a base layer of a generally used protective film, for example, a plastic film as the first base layer.

The first base layer may be a plastic film such as polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyimide (PI), polyethylene terephthalate (PET), and specifically PET. PET is advantageous in terms of durability, mechanical strength, and transparency.

The first base layer may have a thickness of 188 μm or less, 125 μm or less, 100 μm or less, 30 to 188 μm, 30 to 125 μm, 38 to 100 μm, or 50 to 100 μm. Considering the handleability and flexibility aspect, it may have a thickness of 38 to 100 μm.

The first base layer is 10 ⁴ to 10 ¹² Ω/□, 10 ⁴ to 10 ¹¹ Ω/□, or 10 ⁴ to 10 ¹⁰ It can have a surface resistance of Ω/□.

For example, the first base layer has a thickness of 38 to 100 μm and 10 ⁴ to 10 ¹² It can have a surface resistance of Ω/□.

adhesive layer

The protective film according to an embodiment of the present invention includes an adhesive layer derived from the pressure-sensitive adhesive composition.

Detailed description of the pressure-sensitive adhesive composition is the same as described above.

The pressure-sensitive adhesive layer may be obtained by curing the pressure-sensitive adhesive composition with a coating film on one surface of the first base layer. Specifically, the pressure-sensitive adhesive layer may be formed by applying the pressure-sensitive adhesive composition on the first base layer and then heat drying and curing at 100 to 130°C or 110 to 120°C for 1 to 5 minutes, or 1 to 3 minutes. have.

The adhesive layer may have a thickness of 15 to 100 μm, 15 to 95 μm, 15 to 90 μm, 15 to 85 μm, or 15 to 75 μm. It can effectively protect the panel and prevent scratches.

The adhesive layer is 10 ⁸ to 10 ¹² Ω/□, 10 ⁸ to 10 ¹¹ Ω/□, or 10 ⁸ to 10 ¹⁰ It can have a surface resistance of Ω/□.

For example, the adhesive layer has a thickness of 15 to 100 μm and 10 ⁸ to 10 ¹² It can have a surface resistance of Ω/□.

On the other hand, the protective film according to an embodiment of the present invention has a peeling electrification voltage measured at a peeling angle of 180° and a peeling rate of 15 m/min at 25°C and 50% relative humidity (RH) with respect to the adhesive layer of 200 V or less, 180 V or less, 160 V or less, 150 V or less, 140 V or less, 130 V or less, 120 V or less, 110 V or less, 100 V or less, or 90 V or less. The peeling electrification voltage may be 10 V or more, 15 V or more, 20 V or more, 22 V or more, 25 V or more, or 30 V or more.

The peeling electrification voltage refers to the amount of static electricity (voltage) generated on the surface of the adherend during peeling after laminating the protective film to the adherend.

According to an embodiment of the present invention, by using an antistatic agent including two or more kinds of ionic liquids, a low peel electrification voltage of 200 V or less can be easily implemented even with a small amount of the antistatic agent.

In addition, the protective film according to the embodiment of the present invention has little change in physical properties of the adhesive layer over time, such as a change in adhesive force or a decrease in residual adhesive force.

For example, the adhesive force change rate (A (%)) measured with respect to the adhesive layer represented by the following formula 1 may be 50% or less:

[Equation 1]

Ⅹ 100A(%) =

X 100

In Equation 1 above,

A1 is the adhesive force measured by peeling the adhesive layer after attaching it to the adherend at 25° C. for 1 hour,

A2 is the adhesive force measured by peeling the adhesive layer after attaching it to the adherend at 25°C for 30 days.

Specifically, the adhesive force change rate (A (%)) measured for the adhesive layer may be 45% or less, 40% or less, 35% or less, 33% or less, or 30% or less. When within the above range, the rate of change in adhesive strength is not large even after being attached to the adherend for a long time, so that the protective film can be peeled off without deformation or damage of the adherend. If the adhesive force change rate (A (%)) measured for the adhesive layer exceeds the above range, deformation or damage such as bending of the adherend during peeling of the protective film may occur.

A1 is 0.1 to 10 gf / inch, 0.1 to 7 gf / inch, 0.1 to 5 gf / inch, 0.1 to 3 gf / inch, 0.1 to 2.5 gf / inch, 0.1 to 2.2 gf / inch, 0.1 to 2 gf / inch, 0.1 to 1.8 gf/inch, or 0.3 to 1.8 gf/inch.

A2 is 1 to 15 gf / inch, 1 to 8 gf / inch, 1 to 7 gf / inch, 1 to 5 gf / inch, 1 to 4 gf / inch, 1.2 to 3 gf / inch, 1.2 to 2.3 gf / inch, or 1.5 to 2.2 gf/inch.

In addition, the residual adhesive force retention (RA (%)) represented by the following formula 2 for the adhesive layer may be 80% or more:

[Equation 2]

Ⅹ 100RA(%) =

X 100

In Equation 1 above,

N1 is the adhesion of Nitto 31B tape to the adherend,

N2 is the adhesive force of the Nitto 31B tape to the adherend, measured after peeling the adhesive layer by attaching it to the adherend at 60°C and 90% relative humidity (RH) for 120 hours.

Specifically, the residual adhesive force retention (RA (%)) for the adhesive layer is 80% or more, 82% or more, 83% or more, 85% or more, 87% or more, 88% or more, 90% or more, or 92% or more. can

The higher the residual adhesive force retention for the adhesive layer, the less stains or residues left on the surface of the adherend, and the lower the degree of contamination such as whitening.

In addition, the protective film according to the embodiment of the present invention has excellent optical properties such as haze and transmittance.

Specifically, the haze of the protective film may be 5% or less, 4% or less, or 3% or less.

The transmittance of the protective film may be 80% or more, 85% or more, 86% or more, 88% or more, or 90% or more.

The protective film may have, for example, a haze of 5% or less and a transmittance of 80% or more. Specifically, the protective film may have a haze of 4% or less and a transmittance of 85% or more. Alternatively, the protective film may have a haze of 3% or less and a transmittance of 86% or more.

In addition, according to the embodiment of the present invention, when using the pressure-sensitive adhesive composition comprising two or more ionic liquids as an antistatic agent, while maintaining excellent optical properties even with an excessive amount of antistatic agent, low peeling electrification voltage and adhesive strength rate of change, and improved surface contamination results.

release film

The protective film according to an embodiment of the present invention may further include a release film on the other surface of the adhesive layer.

Referring to FIG. 2 , the protective film 1 may include a first base layer 11 , an adhesive layer 12 , and a release film 17 in a sequentially stacked form.

The release film 17 may include a second base layer 14 and a release layer 13 formed on the second base layer 14 . At this time, the adhesive layer 12 and the release layer 13 may be in contact with each other.

In addition, the protective film 1 may further include a first antistatic layer 16 on the other surface of the first base layer 11 , and the release film 17 is formed of the second base layer 14 . A second antistatic layer 15 may be further included on the other surface.

Specifically, the second base layer may include the same components as the first base layer, and may have the same physical properties as the first base layer.

The release layer may include a silicone-based release layer, and a polysiloxane polymer having a group reactive toward a group containing a Si-H bond in a molecule may be used. The group reactive to a group containing a Si-H bond may include at least one selected from the group consisting of an alkenyl group, such as a vinyl group and a hexenyl group.

The thickness of the release layer may be 0.1 to 1 μm, preferably 0.1 to 0.3 μm. If the thickness of the release layer is less than 0.1 μm, it may be difficult to realize the characteristics of the release film, and if it exceeds 1 μm, there may be a possibility of blocking.

The release layer may have a peel force of 5 to 70 gf/inch or less based on Tesa 7475. When in the above range, it may not be separated from the pressure-sensitive adhesive layer alone during the punching process for forming a sheet, and it may be easy to peel the release film during the lamination process.

In the protective film according to an embodiment of the present invention, the pressure-sensitive adhesive composition is applied to one surface of the first base layer and heat-dried to form an adhesive layer, and then a release film, precisely, a release layer of a release film, is formed on one surface of the adhesive layer. It can be prepared by laminating.

As a coating method, for example, a gravure roll coating method, a Mayer bar coating method, a blade coating method, a curtain coating method, a comma coating method, a slot die coating method, etc. can be used, and a comma coating method in consideration of the thickness of the adhesive layer Or a slot die coating method may be preferable.

On the other hand, the first antistatic layer and the second antistatic layer, respectively, a conductive polymer (eg, poly (3,4-ethylenedioxythiophene) (PEDOT)), conventionally known materials, such as an ionic liquid, on the other surface of the base layer It can be formed by a coating method.

The first antistatic layer and the second antistatic layer may have a surface resistance of 10 ¹² Ω/□ or less, 10 ¹⁰ Ω/□ or less, 10 ⁴ to 10 ¹² Ω/□, or 10 ⁴ to 10 ¹⁰ Ω/□ or less. . When it is in the above range, it may be more advantageous in terms of the effect of inhibiting foreign material adsorption.

The protective film according to the embodiment of the present invention has excellent optical properties, wettability and adhesive strength, has low static electricity and peeling electrification voltage during peeling, has low surface contamination of the adherend, and exhibits low physical properties of the adhesive layer over time. Since it is small, it can be usefully used as a protective film during the display panel manufacturing process.

The above will be described in more detail with reference to the following examples. However, the following examples are only for illustrating the present invention, and the scope of the examples is not limited thereto.

Example

Example 1.

<Preparation of adhesive composition>

, M₃BN⁺) 및 NO₃ ^-를 포함하는 제 1 이온성 액체 0.5 중량부, 및 알킬 이미다졸리움 양이온(

, BMI⁺) 및 PF₆ ^-를 포함하는 제 2 이온성 액체 0.5 중량부를 균일하게 혼합하여 점착제 조성물을 제조하였다. Polyol and isocyanate copolymerized polyurethane resin (SH-109, Toyo Ink) 100 parts by weight, hexamethylene diisocyanate trimer (T-501B, Toyo Ink) 7 parts by weight as a diisocyanate curing agent, slip agent (BYK377, BYK) 1 part by weight, tin-based catalyst (BXX3778-10, Toyo Ink) 0.5 part by weight, and an alkylammonium cation as an antistatic agent (

, M ₃ BN ⁺ ) and NO ₃ ⁻ 0.5 parts by weight of a first ionic liquid, and an alkyl imidazolium cation (

, BMI ⁺ ) and PF ₆ ⁻ 0.5 parts by weight of the second ionic liquid containing the ionic liquid was uniformly mixed to prepare a pressure-sensitive adhesive composition.

<Production of protective film>

Prepare a 75 μm thick polyethylene terephthalate (PET) base layer (first base layer) and a 25 μm thick release film (RF02N, SKC hi-tech&marketing), and an adhesive layer between the base layer and the release film To prepare a protective film including a pressure-sensitive adhesive layer having a thickness of 75 ㎛ by applying the pressure-sensitive adhesive composition prepared in Example 1 to one surface of the base layer and drying by heat at 120 ° C. for 3 minutes.

Examples 2 and 3

As shown in Table 1 below, an adhesive composition and a protective film were prepared in the same manner as in Example 1, except that the contents of the first ionic liquid and the second ionic liquid were differently adjusted as antistatic agents.

Comparative Examples 1 to 3

As shown in Table 1 below, an adhesive composition and a protective film were prepared in the same manner as in Example 1, except that LiTFSi was used alone as an antistatic agent and the content thereof was adjusted differently.

Comparative Examples 4 and 5

As shown in Table 1 below, as an antistatic agent, the second ionic liquid containing the alkyl imidazolium cation (BMI ⁺ ) and PF ₆ ⁻ was used alone, and the content thereof was adjusted differently than in Example 1 A pressure-sensitive adhesive composition and a protective film were prepared in the same manner.

Comparative Examples 6 and 7

As shown in Table 1 below, as an antistatic agent, an alkylammonium cation (M3BN ⁺ ) And NO ₃ ^- A pressure-sensitive adhesive composition and a protective film were prepared in the same manner as in Example 1, except that the first ionic liquid was used alone, and the content thereof was adjusted differently.

<Test Example>

Test Example 1: Adhesion

Adhesion change rate

After removing the release film from the protective films prepared in Examples and Comparative Examples, the adhesive layer was attached to the adherend at 25° C. for 1 hour, and then peeled to measure the adhesive force (A1) and the pressure-sensitive adhesive layer at 25° C. for 30 days. The adhesive force (A2) measured by peeling after adhering to the adherend was measured, respectively, and then substituted into the following Equation 1 to obtain the rate of change of adhesive force:

[Equation 1]

Ⅹ 100A(%) =

X 100

Specifically, A1 is the initial adhesive force measured by peeling the adhesive layer after attaching it to the adherend at 25°C for 1 hour. After removal, it was measured by peeling at a 180° angle at a peeling rate of 0.3 m/min after being attached to the glass at 25°C for 1 hour.

The A2 is the adhesive force measured by peeling the adhesive layer after attaching it to the adherend at 25° C. for 30 days. After cutting the protective film prepared in Examples and Comparative Examples to a width of 1 inch, and removing the release film, the glass After attaching at 25°C for 30 days in the state of being attached to the surface, it was measured by peeling at an angle of 180° at a peeling rate of 0.3 m/min.

Residual adhesive force retention (RA(%))

The adhesion (N1) of the Nitto 31B tape to the adherend was measured.

In addition, after removing the release film from the protective films prepared in Examples and Comparative Examples, the adhesive layer was attached to the adherend at 60° C. and 90% relative humidity (RH) for 120 hours and then peeled and measured, Nitto 31B The adhesive force (N2) of the tape to the adherend was measured. By substituting each of the N1 and N2 in the following formula 2, the residual adhesive force retention (RA (%)) was obtained:

[Equation 2]

Ⅹ 100RA(%) =

X 100

Specifically, the N1 was measured by peeling the Nitto 31B tape cut into 1-inch pieces at a 180˚ angle at a peeling rate of 0.3 m/min after leaving it for 1 hour at 25°C in a state of being attached to the glass. is adhesion.

In the N2, the adhesive layer was attached to the glass at 60°C and 90% relative humidity (RH) for 120 hours to peel the protective film, and the Nitto 31B tape cut in 1 inch was attached to the glass. This is the adhesive strength of the Nitto 31B tape measured by peeling it off at a 180° angle at a peeling rate of 0.3 m/min after leaving it at ℃ for 1 hour.

Test Example 2: Surface Contamination Degree

After removing the release film from the protective film prepared in Examples and Comparative Examples, it was attached to glass and left for 120 hours under conditions of 60°C and 90%RH. Thereafter, the protective film was removed and the degree of contamination of the glass surface was visually checked under 3-wavelength illumination.

If no stains or residues remain, PASS, visible stains or whitening, or residues of the adhesive layer were evaluated as NG.

Test Example 3: peel electrification voltage

The protective film prepared in Examples and Comparative Examples was cut to a width of 10 cm x length of 25 cm, and the release film was removed therefrom, and then left attached to the glass at 25° C. for 1 hour, then at 25° C., 50% relative The maximum voltage on the glass surface was measured at a distance of 2 cm while peeling at an angle of 180° at a peel rate of 15 m/min in humidity (RH).

Test Example 4: Haze and Transmittance

After removing the release film from the protective films prepared in Examples and Comparative Examples using a haze meter NDH-5000W of Denshoku Kogyo, Japan, haze and transmittance were measured.

Test Example 5: Surface Resistance

The surface of the adhesive layer of the protective film prepared in Examples and Comparative Examples at 22° C. and 50% relative humidity (RH) using a high ohmmeter (model number MCT-HT450) of Mitsubishi, Japan The surface resistance was measured.

Looking at the experimental results in Table 1, the protective films of Examples 1 to 3 using the pressure-sensitive adhesive composition containing two or more types of ionic liquids as antistatic agents were compared with the protective films of Comparative Examples using one type of metal salt or ionic liquid Thus, while exhibiting the same level of physical properties in terms of optical properties, low peel electrification voltage and adhesive force change rate, excellent residual adhesive force retention and improved surface contamination results were obtained.

Specifically, in the case of the peeling electrification voltage, the protective films of Examples 1 to 3 were 30 to 140 V, which was significantly reduced compared to the protective films of Comparative Examples 1 to 4, 6 and 7, which were 205 V to 490 V, and adhesion. In the case of the change rate of the adhesive force of the layer, the protective films of Examples 1 to 3 were 20% to 33.3%, which was significantly reduced compared to the protective film of Comparative Examples. In particular, it can be seen that in the protective film of Comparative Example 3 using 5 parts by weight of LiTFSi, the change in adhesive strength was significantly increased to 92.9%.

On the other hand, in the case of the residual adhesive force retention using the Nitto 31B tape, the protective films of Examples 1 to 3 were 82% to 93.5%, which was significantly improved compared to the protective film of Comparative Example, and in the case of surface contamination, Example 1 It was confirmed that the protective films of Nos. 3 to 3 did not leave stains or residues, and whitening did not occur.

In addition, comparing the protective films of Example 3 and Comparative Examples 2, 3, 5 and 7 in which the antistatic agent was used in excess of 3 parts by weight or more, the protective film of Example 3 contained an antistatic agent compared to the protective film of the comparative example. Even with excessive use, excellent optical properties were maintained, as well as low peel electrification voltage and adhesive force change rate, and excellent residual adhesive force retention and improved surface contamination were also obtained.

Therefore, from the above results, the protective film of Examples prepared using two different ionic liquids according to an embodiment of the present invention has superior optical properties compared to the protective film of Comparative Example prepared using an antistatic agent alone It was confirmed that all of the improved effects were exhibited in the adhesion force, peeling electrification voltage, physical property change with time, and contamination of the glass surface while maintaining .

1: protective film
11: first base layer
12: adhesive layer
13: release layer
14: second base layer
15: second antistatic layer
16: first antistatic layer
17: release film

Claims (16)

It contains a polyurethane-based resin, a diisocyanate-based curing agent and an antistatic agent,
The antistatic agent comprises two or more ionic liquids,
The at least two ionic liquids include a first ionic liquid containing a hydrophilic anion and a second ionic liquid containing a hydrophobic anion,
The hydrophilic anion is a chloride anion (Cl ⁻ ), a bromide anion (Br ⁻ ), an iodide anion (I ⁻ ), a nitrate anion (NO ₃ ⁻ ) and an acetate anion (CH ₃ CO ₂ ⁻ ) selected from the group consisting of including one or more of which
The hydrophobic anion is a hexafluorophosphate anion (PF ₆ ^- ), a tetrafluoroborate anion (BF ₄ ^- ), a bis((trifluoromethyl)sulfonyl)imide anion (TFSI ^- ) and trifluoromethanesulfo Nate anion (TF ^- ) comprising at least one selected from the group consisting of, the pressure-sensitive adhesive composition.
delete The method of claim 1,
The first ionic liquid and the second ionic liquid are each an alkylimidazolium cation, a dialkylimidazolium cation, a trialkylimidazolium cation, a tetraalkylimidazolium cation, an alkylpyridinium cation, and a dialkylpyri Containing at least one cation selected from the group consisting of dinium cation, dialkylpiperidinium cation, alkylpyrimidinium cation, alkylpyrazolium cation, sulfonium cation, alkylpinolidinium cation, alkylammonium cation and alkylphosphonium cation do,
A pressure-sensitive adhesive composition that does not contain metal ions.
The method of claim 1,
The weight ratio of the first ionic liquid and the second ionic liquid is 1: 0.1 to 2.0, the pressure-sensitive adhesive composition.
The method of claim 1,
The content of the diisocyanate-based curing agent and the antistatic agent is 1 to 10 parts by weight and 0.2 to 6 parts by weight based on 100 parts by weight of the polyurethane-based resin, respectively, the pressure-sensitive adhesive composition.
6. The method of claim 5,
The pressure-sensitive adhesive composition further comprises 0.1 to 10 parts by weight of a slip agent and 0.1 to 5 parts by weight of a catalyst based on 100 parts by weight of the polyurethane-based resin.
a first base layer; and
A pressure-sensitive adhesive layer formed on the first base layer and derived from the pressure-sensitive adhesive composition of any one of claims 1 and 3 to 6;
Containing, a protective film.
8. The method of claim 7,
A protective film, wherein the peel electrification voltage measured at a peel angle of 180° and a peel rate of 15 m/min at 25° C. and 50% relative humidity (RH) with respect to the adhesive layer is 200 V or less.
8. The method of claim 7,
A protective film having an adhesive force change rate (A (%)) of 50% or less as measured by the following formula 1 for the adhesive layer:
[Equation 1]
A(%) =

X 100
In Equation 1 above,
A1 is the adhesive force measured by peeling the adhesive layer after attaching it to the adherend at 25° C. for 1 hour,
A2 is the adhesive force measured by peeling the adhesive layer after attaching it to the adherend at 25°C for 30 days.
8. The method of claim 7,
A protective film having a residual adhesive force retention (RA (%)) of 80% or more, which is represented by the following formula 2 for the adhesive layer:
[Equation 2]
RA(%) =

X 100
In Equation 2 above,
N1 is the adhesion of Nitto 31B tape to the adherend,
N2 is the adhesive force of the Nitto 31B tape to the adherend, measured by peeling the adhesive layer after attaching it to the adherend at 60° C. and 90% relative humidity (RH) for 120 hours.
8. The method of claim 7,
The protective film having a haze of 5% or less and a transmittance of 80% or more.
8. The method of claim 7,
The adhesive layer has a thickness of 15 to 100 μm and 10 ⁸ to 10 ¹² A protective film with a surface resistance of Ω/□.
8. The method of claim 7,
The first base layer has a thickness of 38 to 100 μm and 10 ⁴ to 10 ¹² A protective film with a surface resistance of Ω/□.
8. The method of claim 7,
The protective film, the protective film further comprising a first antistatic layer on the other surface of the first base layer.
8. The method of claim 7,
The protective film further comprises a release film on the other surface of the adhesive layer,
The release film comprises a second base layer and a release layer formed on the second base layer, wherein the adhesive layer and the release layer are in contact with each other, a protective film.
16. The method of claim 15,
The release film further comprises a second antistatic layer on the other surface of the second base layer, the protective film.

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