KR101785380B1 - Adhesive Film - Google Patents

Abstract

The present invention provides an adhesive film comprising a pressure-sensitive adhesive layer on one side of a substrate, wherein the pressure-sensitive adhesive layer has a tensile strength of 4.0 to 20.0 MPa, an elastic modulus of 0.3 to 3.0 MPa, and an elasticity energy storage amount of 9 to 150 MJ Thereby providing an adhesive film. INDUSTRIAL APPLICABILITY The adhesive film according to the present invention can efficiently remove a pressure-sensitive adhesive that has been used in a substrate of an electrical and electronic product without damaging the substrate.

Description

{Adhesive Film}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pressure-sensitive adhesive film, and more particularly, to a pressure-sensitive adhesive film used for removing a residual pressure-sensitive adhesive without damaging a substrate of an electrical and electronic product.

Various electric and electronic products including a display are constituted by various combinations of components, and a fixing method using an adhesive or a pressure-sensitive adhesive is mainly used rather than a mechanical fixing method. In recent years, the use of pressure-sensitive adhesives has been increasing, which requires a fixed time, has a lower fixing force, but is simple in process and consumes less time than an adhesive which is troublesome to store and use.

Such a pressure-sensitive adhesive needs to be peeled off and removed without damaging the parts when it is necessary to separate them from each other due to an error in assembly of the electrical and electronic products. However, if it is difficult to remove the adhesive after it is used on a substrate to be fixed by a pressure-sensitive adhesive, for example, a transparent electrode, a costly substrate is consumed more than necessary and the production cost of the entire display device becomes high. For this reason, a peelable pressure-sensitive adhesive which can be easily separated from a substrate has been developed (see Korean Patent Publication No. 10-2007-0070840).

However, the peelable pressure-sensitive adhesive is somewhat complicated in that it needs to control the curing temperature and methods of the contained polymer in order to facilitate peeling.

Therefore, there is a need to develop a method that can more efficiently remove the adhesive used on a substrate without damaging the substrate.

Korean Patent Publication No. 10-2007-0070840

It is an object of the present invention to provide an adhesive film used for removing a residual adhesive without damaging a substrate.

The present invention provides an adhesive film comprising a pressure-sensitive adhesive layer on one side of a substrate, wherein the pressure-sensitive adhesive layer has a tensile strength of 4.0 to 20.0 MPa, an elastic modulus of 0.3 to 3.0 MPa, and an elasticity energy storage amount of 9 to 150 MJ Thereby providing an adhesive film.

In one embodiment of the present invention, the pressure-sensitive adhesive layer is obtained by mixing a (meth) acrylate monomer having an alkyl group with a monomer having a hydrogen bonding group and subjecting the copolymer to a primary polymerization reaction to obtain a copolymer solution, Adding a mixture of the same monomers as those used in the reaction to obtain a pressure-sensitive adhesive composition by applying the pressure-sensitive adhesive composition onto the substrate, and performing a secondary polymerization reaction.

In one embodiment of the present invention, the monomer having the hydrogen bonding group may be contained in an amount of 50 to 90% by weight based on the total weight of the monomer.

In one embodiment of the present invention, the adhesive film can be used to remove the adhesive remaining on the substrate.

The adhesive film according to the present invention satisfies a predetermined tensile strength, elastic modulus, and elasticity energy storage amount, so that the pressure sensitive adhesive used in the substrate of the electrical and electronic products can be efficiently removed without damaging the substrate.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention is an adhesive film comprising a pressure-sensitive adhesive layer on one side of a substrate, wherein the pressure-sensitive adhesive layer has a tensile strength of 4.0 to 20.0 MPa, an elastic modulus of 0.3 to 3.0 MPa, an elastic position energy storage amount of 9 to 150 MJ Sensitive adhesive film.

In one embodiment of the present invention, the substrate is not particularly limited, and a plastic film such as a polyolefin film such as polyethylene or polypropylene, a polyester film such as polyethylene terephthalate, a paper, a nonwoven fabric, Can be used. A release film may also be used as the substrate. The thickness of the substrate may be generally from 10 to 150 mu m, but is not limited thereto.

In one embodiment of the present invention, the pressure-sensitive adhesive layer satisfies a tensile strength of 4.0 to 20.0 MPa, an elastic modulus of 0.3 to 3.0 MPa, and an elastic position energy storage amount of 9 to 150 MJ. When the tensile strength, the elastic modulus and the elastic energy storage amount exceed the above range, a great deal of force is consumed to remove the adhesive, and the adhesive surface may be damaged before the adhesive is removed. If it is less than the above range, the adhesive film is broken It may be difficult to remove the adhesive.

In the present invention, the method of measuring the tensile strength and the modulus of elasticity is not particularly limited, and can be measured, for example, by the method as described in Experimental Examples described later.

On the other hand, the elastic position energy storage amount refers to the amount of energy that can be sustained until the adhesive film for removing the adhesive is broken. When the tensile strength is measured, the X axis is applied to the deformed length of the adhesive film, Stress-Strain graph drawn when losing force is the area value from the point where the adhesive film breaks.

In short, it is possible to obtain the approximation of the width by assuming that the adhesive film is an elastic body according to the following equation (1), and the integral value of the graph can be accurately used according to the following equation (2).

[Equation 1]

In this formula,

는 점착필름의 탄성계수이고,

Is the elastic modulus of the adhesive film,

는 점착필름의 인장한계 변형길이, 즉 점착필름이 파단되는 시점에서의 변형길이이다.

Is the tensile limit deformation length of the adhesive film, that is, the deformation length at the time when the adhesive film is broken.

&Quot; (2) "

In this formula,

은 점착필름의 변형길이이고,

Is the deformation length of the adhesive film,

은 점착필름의 변형길이에 따른 탄성력이며,

Is an elastic force according to the deformation length of the adhesive film,

는 점착필름의 인장한계 변형길이이다.

Is the tensile limit deformation length of the adhesive film.

In one embodiment of the present invention, the pressure-sensitive adhesive layer is obtained by mixing a (meth) acrylate monomer having an alkyl group with a monomer having a hydrogen bonding group and subjecting the copolymer to a primary polymerization reaction to obtain a copolymer solution, Adding a mixture of the same monomers as those used in the reaction to obtain a pressure-sensitive adhesive composition by applying the pressure-sensitive adhesive composition onto the substrate, and performing a secondary polymerization reaction.

The thus formed pressure-sensitive adhesive layer can increase the tensile strength, the elastic modulus and the elastic energy storage amount by increasing the main chain length of the polymer by introducing the functional group which strengthens the hydrogen bond and increasing the intermolecular and intermolecular interactions.

In one embodiment of the present invention, the pressure-sensitive adhesive layer is formed by appropriately changing the type and composition of a (meth) acrylate monomer having an alkyl group and a monomer having a hydrogen bonding group, the conditions of the primary and secondary polymerization reactions, The elastic modulus and the elasticity energy storage amount can be easily controlled.

The (meth) acrylate monomer having an alkyl group is specifically a (meth) acrylate monomer having an alkyl group having from 1 to 12 carbon atoms, such as n-butyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, isopropyl (meth) acrylate, isopropyl (meth) acrylate, (Meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl 2-ethylhexyl (meth) acrylate is preferred. These may be used alone or in combination of two or more.

Examples of the monomer having a hydrogen-bonding group include a monomer having a hydroxyl group, a monomer having an amide group, and a monomer having a tertiary amine group. These monomers may be used alone or in combination of two or more.

Examples of the monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl Hydroxypropyleneglycol (meth) acrylate, hydroxyalkylene glycol having 2 to 4 carbon atoms in the alkylene group (e.g., methoxyethyl (meth) acrylate, Hydroxybutyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxynonyl (meth) acrylate, 4-hydroxybutyl vinyl ether, Vinyl ether, and 10-hydroxydecyl vinyl ether. Of these, 2-hydroxyethyl (meth) acrylate is preferable.

Examples of the monomer having an amide group include (meth) acrylamide, N, N-dimethylacrylamide, N-isopropylacrylamide, Nt-butyl acrylamide, 3- hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (Meth) acrylamide, 6-hydroxyhexyl (meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide and 2-hydroxyethylhexyl Dimethyl acrylamide is preferred.

Examples of the monomer having a tertiary amine group include N, N- (dimethylamino) ethyl (meth) acrylate, N, N- (diethylamino) ethyl (meth) ) Acrylate, and the like.

The monomer having the hydrogen bonding group may be contained in an amount of 50 to 90% by weight based on the total weight of the monomer. When the content is less than 50% by weight, there is a problem that the tensile strength is drastically decreased. When the content is more than 90% by weight, the initial peeling force rising speed is too low, and the waiting time for removing the adhesive may become long.

In forming the pressure-sensitive adhesive layer, the curing may be performed by a conventional curing method such as heat curing or photo-curing, and in the case of photo-curing, a suitable photoinitiator may be used depending on the composition of the pressure-sensitive adhesive layer.

Examples of the photoinitiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide,?,? -Methoxy-? -Hydroxyacetophenone, 2 1-butanone, 2,2-dimethoxy 2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, and the like can be used. However, the present invention is not limited thereto.

Further, the pressure-sensitive adhesive composition may further include a crosslinking agent if necessary.

Examples of the crosslinking agent include polyfunctional acrylates such as 1,6-hexanediol diacrylate, triethylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, ethylene Glycol diacrylate, 1,12-dodecanediol acrylate, and the like, but are not limited thereto.

In addition, the pressure-sensitive adhesive composition may further include a solvent commonly used in polymerization of the acrylic copolymer, a chain transfer agent for controlling the molecular weight, and the like.

At the time of forming the pressure-sensitive adhesive layer, the application can be generally performed by a knife coater, a roll coater, a calendar coater, a comma coater or the like. Depending on the coating thickness and the viscosity of the pressure-sensitive adhesive composition, it may be carried out by a gravure coater, a rod coater or the like.

In one embodiment of the present invention, the thickness of the pressure-sensitive adhesive layer may be 10-1,000 탆, but is not limited thereto. If the thickness is less than 10 탆, the strength of the pressure-sensitive adhesive film for removing the pressure-sensitive adhesive may be lowered. If the thickness is more than 1,000 탆, the production cost may increase, and the pressure may become greater than necessary.

The above-mentioned pressure-sensitive adhesive film in which the pressure-sensitive adhesive layer is formed on a substrate has a high adhesive force to a substrate of an electric and electronic product such as a silicon oxide substrate or a pressure-sensitive adhesive strongly adhered to a polycarbonate substrate on which a visible light- On the other hand, since the adhesive force to the substrate is low, the pressure sensitive adhesive can be efficiently removed without damaging the substrate.

The adhesive film according to an embodiment of the present invention may have a structure in which a first substrate and a second substrate are laminated on both surfaces of a pressure-sensitive adhesive layer, and at least one of the first substrate and the second substrate may be a release film.

Hereinafter, the present invention will be described more specifically with reference to Examples, Comparative Examples and Experimental Examples. It should be apparent to those skilled in the art that these examples, comparative examples and experimental examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example  1 to 3: Production of adhesive film

(Unit: weight ratio / wt%), and the mixture was polymerized up to 60 ° C starting from a temperature of 20 ° C, and a monomer mixture having the same composition was added to the resultant copolymer solution to dilute To prepare a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition prepared above was coated on a release film having a thickness of 75 탆 at a thickness of 100 탆 and irradiated with 1000 mJ using mercury vapor to produce a pressure-sensitive adhesive film having a pressure-sensitive adhesive layer.

Example 1 Example 2 Example 3 2-EHA 4 2 10 2-HEA 6 3 5 DMAA 5 5 5 Cross-linking agent 0.075 0.075 0.075 Photoinitiator 0.05 0.05 0.05 Chain transfer agent 0.025 0.025 0.025

2-EHA: 2-ethylhexyl acrylate

2-HEA: 2-hydroxyethyl acrylate

DMAA: N, N-dimethylacrylamide

Crosslinking agent: Tripropylene glycol diacrylate

Photoinitiator: 1-hydroxycyclohexyl phenyl ketone

Chain transfer agent: pentaerythritol tetrakis mercaptopropionate

Experimental Example 1:

The physical properties of the pressure-sensitive adhesive films prepared in the above Examples were measured by the following methods, and the results are shown in Table 2 below. On the other hand, in the comparative example, an acrylic acid-based adhesive film (product name: FP6080, manufactured by Shenzhen Chengdu Sungguk Shin Co., Ltd., China) was used.

(1) Tensile strength and elastic modulus

The specimens cut into 10 mm × 70 mm were tested by tensile strength of 10 mm on the upper and lower grippers spaced apart by 50 mm from the universal testing machine. The value obtained by dividing the applied force at the time of destruction of the sample by the sectional area of the sample is the tensile strength.

On the other hand, the elastic modulus was calculated by dividing the tensile strength by "the length of strain at the time of destruction of the sample / initial length of the sample".

(2) Elastic position energy storage amount

The elastic position energy storage amount was calculated using the following equation (2). Specifically, the width from x = 0 to x = strain length at break was calculated from the graph drawn when the deformation length of the sample was measured on the x-axis and the force on the sample was plotted on the y-axis.

&Quot; (2) "

In this formula,

은 점착필름의 변형길이이고,

Is the deformation length of the adhesive film,

은 점착필름의 변형길이에 따른 탄성력이며,

Is an elastic force according to the deformation length of the adhesive film,

는 점착필름의 인장한계 변형길이이다.

Is the tensile limit deformation length of the adhesive film.

(3) Peel force on the substrate

The produced adhesive film was cut into a size of 100 mm x 25 mm to obtain a measurement specimen. The specimen was attached to a silicon oxide substrate, and the 180 peel force was measured by a universal testing machine.

(4) Adhesive removal efficiency

The obtained pressure-sensitive adhesive film was cut into a size of 60 mm x 150 mm to obtain a test specimen. After adhesion of the pressure-sensitive adhesive to the silicon oxide substrate to which the pressure-sensitive adhesive was adhered and detachment of the pressure-sensitive adhesive, the presence of the pressure- To evaluate the adhesive removal efficiency.

<Evaluation Criteria>

X: When the adhesive is not removed by 50% or more

DELTA: When the pressure-sensitive adhesive was removed to a degree of 50 to 90%

○: When the adhesive is almost removed, but the remnant of the intermediate adhesive remains

◎: Most of adhesive removed without residue

Example 1 Example 2 Example 3 Comparative Example 1 Tensile Strength (MPa) 7.43 15.0 4.73 0.97 Modulus of elasticity (MPa) 1.25 2.38 2.48 0.09 Elastic Position Energy Storage (MJ) 48.0 141 9.02 9.99 Peel force on the substrate (N / m) 77 58 89 784 Adhesive Removal Efficiency ◎ ◎ ○ △

As can be seen from Table 2, in Examples 1 to 4 having a pressure-sensitive adhesive layer having a tensile strength of 4.0 to 20.0 MPa, an elastic modulus of 0.3 to 3.0 MPa, and an elasticity energy storage amount of 9 to 150 MJ, 3 had a low peeling force against the silicon oxide substrate and had a high removal efficiency of the adhesive which was strongly adhered to the substrate. On the other hand, in the case of Comparative Example 1, the physical properties of the pressure-sensitive adhesive layer did not satisfy such conditions, so that the peeling force against the silicon oxide substrate was high and the removal efficiency of the pressure-sensitive adhesive adhered to the substrate was poor.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Do. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

Claims (10)

A pressure-sensitive adhesive film comprising a pressure-sensitive adhesive layer on one surface of a substrate, wherein the pressure-sensitive adhesive layer has a tensile strength of 4.0 to 20.0 MPa, an elastic modulus of 0.3 to 3.0 MPa, and an elastic position energy storage amount of 9 to 150 MJ. The adhesive film according to claim 1, wherein the substrate is a release film. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer is prepared by mixing a (meth) acrylate monomer having an alkyl group with a monomer having a hydrogen bonding group and subjecting the copolymer to a primary polymerization reaction to obtain a copolymer solution, An adhesive film is formed by adding a mixture of the same monomers as those used to obtain a pressure-sensitive adhesive composition by diluting, applying the pressure-sensitive adhesive composition onto a substrate and performing a secondary polymerization reaction. The adhesive film according to claim 3, wherein the monomer having the hydrogen bonding group is contained in an amount of 50 to 90% by weight based on the total weight of the monomer. The adhesive film according to claim 3, wherein the pressure-sensitive adhesive composition further comprises at least one of a photoinitiator, a crosslinking agent and a chain transfer agent. The pressure-sensitive adhesive film according to claim 1, wherein the thickness of the pressure-sensitive adhesive layer is in the range of 10 to 1,000 占 퐉. The adhesive film according to claim 1, which is used for removing the adhesive remaining on the substrate. The adhesive film according to claim 7, wherein the substrate is a silicon oxide substrate or a polycarbonate substrate. Wherein the pressure-sensitive adhesive layer has a tensile strength of 4.0 to 20.0 MPa, an elastic modulus of 0.3 to 3.0 MPa, and an elastic position energy storage amount of 9 to 150 MJ Sensitive adhesive film. The adhesive film according to claim 9, wherein at least one of the first base material and the second base material is a release film.