KR20190107347A - Base film having improved resistance to tension fatigue - Google Patents

Abstract

A coefficient of deformation resistance of a base film according to the present invention is greater than 0 and less than 0.1. Here, the coefficient of deformation resistance is ε_N/Δσ_N, wherein ε_N is the ratio of the permanent strain length according to the tension of the base film, and Δσ_N is the amount of change in tensile stress. According to the present invention, it is possible to predefine reliable property parameters related to the stretchable properties of the base film, and to apply the base film that meets the property parameters to the touch sensor, thereby reducing the defect of the touch sensor and improving the product process yield.

Description

Base film with improved deformation resistance to tensile fatigue {BASE FILM HAVING IMPROVED RESISTANCE TO TENSION FATIGUE}

The present invention relates to a base film. More specifically, the present invention predefine reliable property parameters related to the stretchable properties of the base film and apply them to the touch sensor only for the base film that meets these property parameters, thereby reducing the failure of the touch sensor and producing the product process. It relates to a technique that allows to improve the yield.

Recently, with the development of display-related technology, flexible display devices that can be folded or rolled into a roll shape have been researched and developed. Further, stretchable display devices that can be transformed into various forms are further developed. Korea's research and development is actively progressing.

The stretchable display device also has a touch sensor having a stretchable property to sense and process a user input by a touch method.

Meanwhile, the base film, which is one of the components of the stretchable touch sensor, has a large influence on the stretchable characteristics of the touch sensor and the display to which the touch sensor is applied, and the other components of the touch sensor are related to the stretchable characteristics. If the base film does not meet these physical property conditions even if the conditions are met, there is a problem that the stretchable characteristics of the touch sensor are greatly reduced.

Therefore, prior to applying the base film to the touch sensor, it is necessary to define the physical properties related to the stretchable properties of the base film in advance, and by applying the touch film only to the base film that satisfies this property, the defect of the touch sensor is prevented. There is a need to reduce and improve process yield.

Republic of Korea Patent Application Publication No. 10-2014-0118512 (published date: October 08, 2014, name: flexible / stretchable transparent conductive film and method for manufacturing the same)

The present invention can predefine reliable property parameters related to the stretchable properties of the base film and apply them to the touch sensor only for the base film that meets these property parameters, thereby reducing the failure of the touch sensor and improving the product process yield. It is technical problem to make it possible.

The deformation resistance coefficient of the base film according to the present invention for solving this technical problem is more than 0 and less than 0.1.

Here, the deformation resistance coefficient = ε _N / Δσ _N , ε _N is the ratio of the permanent strain length according to the tension of the base film, Δσ _N is the amount of change in tensile stress.

The thickness of the base film which concerns on this invention is 50 micrometers-300 micrometers.

In the base film according to the present invention, the permanent deformation length ratio ε _N is a ratio of the length of the base film before stretching to the amount of change in the length of the base film before and after stretching.

In the base film according to the present invention, the permanent strain length ratio ε _N is greater than 0 and less than 0.005.

In the base film according to the present invention, the amount of change in tensile stress (Δσ _N ) is greater than 0 and less than 0.1.

The base film according to the present invention is one selected from the group consisting of PDMS (Polydimethylsiloxane), PET (Polyehtylene-terephthalate), PES (Polyether sulfone), PEN (Polyethylenenaphthalate), PI (Polyimide), PMMA (Polymethymethacrylate), PC (Polycarbonate) It includes the above.

The touch screen according to the invention comprises the base film according to the invention.

According to the present invention, it is possible to predefine reliable property parameters related to the stretchable properties of the base film, and to apply them to the touch sensor only for the base film meeting the property parameters, thereby reducing the defect of the touch sensor and improving the product process yield. There is an effect that can be improved.

1 is a view showing a base film that is not subjected to a tensile / recovery test in one embodiment of the present invention,
2 is a view showing a state in which the base film is tensioned by applying a tensile force to the base film in the tensile / recovery test process in an embodiment of the present invention,
3 is a view showing the base film after the tensile / recovery test in one embodiment of the present invention.

Specific structural or functional descriptions of the embodiments according to the inventive concept disclosed herein are provided only for the purpose of describing the embodiments according to the inventive concept. It may be embodied in various forms and is not limited to the embodiments described herein.

Embodiments according to the inventive concept may be variously modified and have various forms, so embodiments are illustrated in the drawings and described in detail herein. However, this is not intended to limit the embodiments in accordance with the concept of the invention to the specific forms disclosed, it includes all changes, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first or second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another, for example without departing from the scope of the rights according to the inventive concept, and the first component may be called a second component and similarly the second component. The component may also be referred to as the first component.

When a component is said to be "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may exist in the middle. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle. Other expressions describing the relationship between components, such as "between" and "immediately between" or "neighboring to" and "directly neighboring", should be interpreted as well.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described herein, but one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined herein. Do not.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a view showing a base film that is not subjected to a tensile / recovery test in one embodiment of the present invention, Figure 2 is a tensile force is applied to the base film during the tensile / recovery test in an embodiment of the present invention 3 is a view showing a state in which the base film is tensioned, and FIG. 3 is a view showing the base film after the tensile / recovery test is finished in one embodiment of the present invention.

1 to 3, an embodiment of the present invention is a substrate film having improved deformation resistance to tensile fatigue, and a permanent deformation length ratio of the substrate film after a plurality of tensile / recovery tests on the substrate film (ε _N ) The deformation resistance coefficient (ε _N / Δσ _N ), which is the ratio of the change in tensile stress (Δσ _N ), is greater than 0 and less than 0.1.

Although described in the process of describing the background art, for example, the substrate film, which is one of the components of the stretchable touch sensor, has a great influence on the stretchable characteristics of the touch sensor and the display to which the touch sensor is applied. Even if other components of the touch sensor satisfy the physical property condition related to the stretchable property, when the base film does not satisfy the physical property condition, there is a problem that the stretchable property of the touch sensor is greatly degraded.

Therefore, prior to applying the base film to the touch sensor, it is necessary to define the physical properties related to the stretchable properties of the base film in advance, and by applying the touch film only to the base film that satisfies this property, the defect of the touch sensor is prevented. There is a need to reduce and improve process yield.

In one embodiment of the present invention, the deformation resistance (ε _N / Δσ _N ) is a novel physical property parameter that enables to predefine the stretchable properties of the base film derived from such a background with high reliability.

The deformation resistance coefficient (ε _N / Δσ _N ) is described in more detail as follows.

The deformation resistance (ε _N / Δσ _N ) is a ratio of the permanent strain length ratio (ε _N ) and the tensile stress change amount (Δσ _N ) of the base film after a plurality of tensile / recovery tests on the base film.

For example, the permanent strain length ratio ε _N may be a ratio of the length of the base film before stretching to the amount of change in the length of the base film before and after stretching. Referring to the example disclosed in FIG. 3, the length of the base film before stretching is L, the length of the base film which is permanently stretched after stretching is L + 2L1, and the permanent strain length ratio ε _N is 2 × L1 / L. For example, the unit of the change in tensile stress amount Δσ _N may be MPa.

The base film according to an embodiment of the present invention satisfies the condition that the deformation resistance (ε _N / Δσ _N ) is greater than 0 and less than 0.1.

For example, PDMS (Polydimethylsiloxane), which is a main material of the stretchable film, has excellent elasticity, that is, a stretchable property, but when the tensile / recovery test is repeated N times or more, the performance tends to decrease due to permanent deformation. Upon recovery after 50% tension, if the ratio of the permanent strain length (ε _N ) and tensile stress change (Δσ _N ) of the film at any N times is less than 0.1, it may be considered to be resistant to deformation. Tolerance to deformation means no change to initial physical deformation. That is, if it is determined that there is deformation resistance, it is commercially available as a stretchable base material, and when the base material is applied to the touch sensor, the stretchable property of the touch sensor can be secured stably.

For example, in order to ensure stable and reliable stretchable properties, the thickness of the base film is preferably 50 µm-300 µm.

For example, the permanent strain length ratio ε _N may be greater than 0 and less than 0.005, and the amount of change in tensile stress Δσ _N may be greater than 0 and less than 0.1. A base film that meets these conditions can ensure stable and reliable stretchable properties even after repeated stretching and recovery.

For example, the base film is one selected from the group consisting of polydimethylsiloxane (PDMS), polyethylene-terephthalate (PET), polyether sulfone (PES), polyethylenenaphthalate (PEN), polyimide (PI), polymethymethacrylate (PMMA), and polycarbonate (PC). It may contain the above.

As a more specific example, the base film may be composed of any material having excellent stretchable properties and light transmittance.

For example, the base film may be a transparent optical film or a polarizing plate.

For example, a film having excellent transparency, mechanical strength, and thermal stability may be used as the transparent optical film, and specific examples thereof include polyesters such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and polybutylene terephthalate. Suzy; Cellulose resins such as diacetyl cellulose and triacetyl cellulose; Polycarbonate resins; Acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; Styrene resins such as polystyrene and acrylonitrile-styrene copolymers; Polyolefin-based resins such as polyethylene, polypropylene, cyclo-based or norbornene-structured polyolefins, ethylene-propylene copolymers; Vinyl chloride-based resins; Amide resins such as nylon and aromatic polyamides; Imide resin; Polyether sulfone resin; Sulfone resins; Polyether ether ketone resins; Sulfided polyphenylene resins; Vinyl alcohol-based resins; Vinylidene chloride-based resins; Vinyl butyral resin; Allyl resins; Polyoxymethylene resin; And films composed of thermoplastic resins such as epoxy resins, and the like, and films composed of blends of the above thermoplastic resins may also be used. Moreover, the film of thermosetting resin or ultraviolet curable resin, such as (meth) acrylic-type, urethane type, acrylurethane type, epoxy type, and silicone type, can also be used. Although the thickness of such a transparent optical film can be suitably determined, generally, it can be determined to 1-500 micrometers in consideration of workability, thinness, etc., such as intensity | strength and handleability. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable.

Such a transparent optical film may contain an appropriate one or more additives. As an additive, a ultraviolet absorber, antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, a coloring agent, etc. are mentioned, for example. The transparent optical film may have a structure including various functional layers such as a hard coating layer, an antireflection layer, and a gas barrier layer on one or both surfaces of the film, and the functional layer is not limited to the above-described ones, and various functional layers may be formed depending on the purpose. It may include.

In addition, the transparent optical film may be surface-treated as needed. Such surface treatments include, for example, plasma treatments, corona treatments, dry treatments such as primer treatments, and chemical treatments such as alkali treatments including saponification treatments.

In addition, the transparent optical film may be an isotropic film, a retardation film or a protective film.

In the case of an isotropic film, in-plane retardation (Ro, Ro = [(nx-ny) ⅹd], nx, ny are principal refractive indices in the film plane, and d is film thickness) is 40 nm or less, preferably 15 nm or less, and the thickness direction Retardation (Rth, Rth = [(nx + ny) / 2-nz] _d, nx, ny are principal refractive index in a film plane, nz is refractive index of a film thickness direction, d is film thickness.) -90nm-+ 75nm It is preferably -80 nm to +60 nm, particularly -70 nm to +45 nm.

Retardation film is a film produced by the method of uniaxial stretching, biaxial stretching, polymer coating, liquid crystal coating of a polymer film, and is generally used for improving and controlling optical properties such as viewing angle compensation, color improvement, light leakage, and color taste control of a display. do. Types of the retardation film include a wave plate such as 1/2 or 1/4, a positive C plate, a negative C plate, a positive A plate, a negative A plate, and a biaxial wave plate.

The protective film may be a film including an adhesive layer on at least one surface of a film made of a polymer resin, or a film having a self-adhesive property such as polypropylene, and may be used to protect the touch sensor surface and improve processability.

As a polarizing plate, a well-known thing used for a display panel can be used. Specifically, a polyvinyl alcohol film is drawn to form a protective layer on at least one surface of a polarizer dyed iodine or a dichroic dye, made by orienting the liquid crystal to have the performance of the polarizer, polyvinyl film on a transparent film And coating the alignment resin such as alcohol, stretching and dyeing the same, and the like, but are not limited thereto.

According to the present invention as described in detail above, the touch sensor defects by pre-defining reliable property parameters related to the stretchable properties of the base film, and applying to the touch sensor only to the base film satisfying this property parameter It has the effect of reducing the yield and improving the product process yield.

Experimental Example

Referring to Table 1, the tensile / recovery test applied to an embodiment of the present invention and the results are described as follows.

Autograph (shimadzu Co., Ltd.) was used as the tension / recovery test device, the specimen was stretched at a speed of 12 mm / min, PDMS (Polydimethylsiloxane) having a width of 10 mm was used, and the gage distance was set to 50 mm. Tensile elongation was repeated 100,000 times at a rate of 12 mm / min in the tensile elongation 0↔50% section was carried out tensile test.

PDMS of Examples 1 and 2 were made of Sylgard184 (Dow Corning), which is a mixture of a resin and a curing agent, and a polysilane-based resin and a curing agent for Sylgard184 were used. The PDMS of Comparative Examples 1 and 2 was a mixture of a resin and a curing agent. It was made of MS1002 (Dow Corning Co., Ltd.), a polysilane-based resin and a curing agent for MS1002 were used. The PDMS of Comparative Example 3 was made of Silicone RTV 615 (General Electronic Co., Ltd.), a mixture of resin and hardener, and polysilane. A series of resins and curing agents for Silicone RTV 615 were used, the weight ratios of resins and curing agents in each example are shown in Table 1.

Item Resin and Hardener
(Resin (wt%) /
Hardener (% by weight)) Early
Base Film
Length (mm) After 100,000 times of tension
Permanently deformed
Base Film
Length (mm) Early
Tensile stress
(MPa) 100,000 times
After tension
Tensile stress
(MPa)
Example 1 Sylgard184
(90/10) 50 50.2 0.004 0.07 Example 2 Sylgard184
(80/20) 50 50.1 0.002 0.04 Comparative Example 1 MS1002
(90/10) 50 51.5 0.030 0.27 Comparative Example 2 MS1002
(80/20) 50 51.1 0.022 0.18 Comparative Example 3 Silicone RTV 615
(90/10) 50 52.1 0.042 0.26

The crack evaluation disclosed in Table 2 is a result of observing the crack after the sample after the tensile / recovery test with an optical microscope (ECLIPSE LV100ND, NIKON Corporation), 1) when no crack occurred, marked with ○, 2) crack When 1-5 were observed, it was indicated by △, and 3) when 6 or more cracks were observed, it was indicated by X.

Item Permanent deformation
ratio
(ε _N ) Tensile stress
Change
(Δσ _N ) Deformation resistance
Coefficient Crack rating Example 1 0.004 0.066 0.062 ○ Example 2 0.002 0.038 0.053 ○ Comparative Example 1 0.030 0.240 0.125 × Comparative Example 2 0.022 0.158 0.139 △ Comparative Example 3 0.042 0.218 0.193 ×

Referring to Table 2, in Examples 1 and 2, 0 <Strain coefficient <0.1 was satisfied, after the tensile / recovery repeated fatigue test was performed, it was confirmed that the sample does not change the appearance and the crack evaluation results are also good Could.

In Comparative Examples 1, 2, and 3, 0 <the strain resistance <0.1 was not satisfied, and after the tensile / recovery repeated fatigue test was performed, the sample was stretched, the appearance was changed, or the crack evaluation result was confirmed to be poor. Could.

Claims (7)

The base film whose deformation resistance coefficient is more than 0 and less than 0.1.
(Strain resistance = ε _N / Δσ _N , ε _N is the ratio of permanent strain length according to the tension of the base film, Δσ _N is the amount of change in tensile stress)
The method of claim 1,
The thickness of the said base film is a base film of 50 micrometers-300 micrometers.
The method of claim 1,
The permanent deformation length ratio ε _N is a ratio of the length of the base film before tension to the amount of change in the length of the base film before and after tension.
The method of claim 3,
The permanent deformation length ratio (ε _N ) is greater than 0 and less than 0.005, the base film.
The method of claim 1,
The amount of change in tensile stress (Δσ _N ) is greater than 0 and less than 0.1, the base film.
The method of claim 1,
The base film may include at least one selected from the group consisting of polydimethylsiloxane (PDMS), polyethylene-terephthalate (PET), polyether sulfone (PES), polyethylenenaphthalate (PEN), polyimide (PI), polymethymethacrylate (PMMA), and polycarbonate (PC). Base film to say.
A touch screen comprising the base film of any one of claims 1 to 6.

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