KR20120009617A - Lcd protection film comprising permanent antistatic agent - Google Patents

Abstract

PURPOSE: An environment-friendly LCD protection film is provided to prevent the transfer of antistatic agent and other additives to LCD display even at high temperatures and high humidity environments. CONSTITUTION: An LCD protection film comprises: a first layer including medium density polyethylene, low density polyethylene, and a permanent antistatic agent; a second layer including medium density polyethylene or high density polyethylene, and low density polyethylene; and a third layer including medium density polyethylene, low density polyethylene, and a permanent antistatic agent. The first, second, and third layers are laminated in order.

Description

LCD protective film containing permanent antistatic agent {LCD PROTECTION FILM COMPRISING PERMANENT ANTISTATIC AGENT}

The present invention relates to a protective film attached to the front of the LCD screen in order to protect the LCD screen, and specifically relates to a three-layer polyethylene protective film for LCD including a permanent antistatic agent.

Display-related devices, such as LCD modules, polarizers, TVs, notebook computers, and monitors, contain a functional protective film on the screen to prevent contamination and surface scratches caused by dust or dirt in the air during transportation, storage or processing. It is generally handled in an attached state.

In particular, in the latest display devices, cleanliness management is very important to maintain a clean and clean screen state from the production and packaging of the product to supplying to the final consumer. For this purpose, it is common to use polyester (PET) protective film.

PET protective film is characterized by excellent transparency, tensile strength, impact resistance and solvent resistance, but due to its high stiffness, it may cause surface scratches on adherends such as LCD screens. Because of this high cost, there was a big problem with the cost of raw materials.

In addition, in order to prevent contamination of the protective film, a method of coating a liquid antistatic agent and other additives on the surface of the protective film has been developed. However, this method has excellent antistatic effect, but is transferred to the surface of the film under high temperature and high humidity conditions and the LCD screen has been developed. The back may be contaminated.

Conventional LCD protective film mainly used anti-static (AS) coating on the surface of polyester (PET) film with a thickness of 100㎛, and the stiffness is high. Due to the use, the scratch on the LCD screen is severe, the cost of the material itself is high, and there is a problem that an additional process is required for the antistatic coating. (See Figure 2)

In addition, as a film for LCD protection having a three-layer structure, a film prepared by laminating a 40㎛ thick film of polyethylene (PE) and a permanent antistatic agent on both sides of a 40㎛ polyester film (PET) film (PE) + AS / PET / PE + AS) was also used. It also has a high stiffness by using a polyester film as an intermediate layer, but it has a structure in which two different resins are attached by an adhesive, which makes it difficult to recycle and the cost of the material itself is still high. Since the film laminating process must be performed twice, there is a problem that the production process is increased and the film thickness is thick. (See Fig. 3)

The present invention is lighter and more flexible than the film of polyester (PET) material used as the protective film for LCD, and does not damage the LCD screen, and the manufacturing process is simple while satisfying the required physical properties equivalent to that of the PET film. Its purpose is to provide an LCD protective film at a much lower cost, and it is provided with an antistatic agent, which is provided with an antistatic property, thereby preventing contamination from dust and dirt during LCD manufacturing and transportation. An object of the present invention is to provide an environmentally friendly LCD protective film in which antistatic agents and other additives are not transferred to the LCD screen even in a high temperature and high humidity environment.

The present invention comprises a first layer comprising a medium density polyethylene, a low density polyethylene and a permanent antistatic agent; A second layer comprising medium or high density polyethylene and low density polyethylene; And it provides a LCD protective film characterized in that the third layer comprising a medium density polyethylene, a low density polyethylene and a permanent antistatic agent is sequentially laminated.

The present invention also provides a first composition comprising medium density polyethylene, low density polyethylene and permanent antistatic agent, a second composition comprising medium or high density polyethylene and low density polyethylene, and medium density polyethylene, low density polyethylene and permanent antistatic agent Preparing each of the third compositions comprising; And it provides a method for producing an LCD protective film comprising the step of co-extrusion the first to third compositions.

The protective film for LCD according to the present invention is lighter and more flexible than the film of polyester (PET) material used as the conventional protective film for LCD, and does not damage the LCD screen, and requires the same physical properties as the PET film. While satisfactory, the manufacturing cost is much cheaper. In addition, the permanent antistatic agent is included in the film to impart antistatic properties, thereby preventing contamination from dust and dirt during the LCD manufacturing process and transportation, and the antistatic agent and other additives are added to the LCD screen even in a high temperature and high humidity environment. There is an advantage that is not implemented. In addition, since each layer of the film is made of a polyethylene material, it is easy to recycle the film, and is manufactured by a triple coextrusion method, so that the manufacturing process is very simple.

1 is a schematic view showing a cross section of the LCD protective film of the present invention.
2 and 3 are schematic diagrams showing a cross section of a conventional LCD protective film.

As used herein, the term stiffness (stiffness), as a dictionary definition, refers to a numerical value of the degree to which the material resists a given deformation when the material is externally deformed. The practical meaning is the degree of stiffness of the film, which is subjectively determined by the experimenter whether the touch is stiff or soft when the film is touched by hand, and the higher the stiffness, the more stiff the touch.

The present invention provides an LCD protective film, comprising: a first layer comprising a medium density polyethylene, a low density polyethylene, and a permanent antistatic agent; A second layer comprising medium or high density polyethylene and low density polyethylene; And a third layer comprising a medium density polyethylene, a low density polyethylene, and a permanent antistatic agent.

LCD protective film of the present invention can be produced by a three-layer coextrusion method because it is made to have a three-layer structure only with a polyethylene film, and accordingly unlike the existing three-layer film (PE + AS / PET / PE + AS) There is no need for a separate lamination process, it is environmentally friendly because no adhesive is used, and there is an advantage in that the recycling of the film after use is very easy.

In addition, by including a permanent antistatic agent in the film of the first and third layers can be manufactured at once without a separate antistatic agent coating process, the process is very simple, using a low-cost material PE can reduce the cost. .

In addition, the LCD protective film of the present invention, by adjusting the mixing ratio of the medium density polyethylene and the low density polyethylene in accordance with the properties of the polyethylene material, while ensuring the mechanical strength of the level required by the LCD manufacturer, because the material is soft, the LCD screen There is an advantage that does not generate a scratch (Scratch).

In the case of the LCD protective film of the present invention having a three-layer film structure in which the physical properties of the first layer, the second layer, and the third layer are different as described above, the first layer and the first layer and the permanent antistatic agent added in a solid pellet form The three layers can prevent contamination or foreign matters when attached to the adherend, can suppress contamination due to the material on the substrate of the adherend, and at the same time can prevent dust and foreign matters from adhering to the outer layer of the film. have. In addition, the second layer adjusts the weight ratio of medium or high density polyethylene and low density polyethylene to have a higher stiffness than the first layer and the third layer, thereby improving robustness to facilitate handling and adhesion of the film. You can. In this case, the first layer and the third layer may be of a different composition, but preferably may be of the same composition.

In the LCD protective film of the present invention, the weight ratio of the medium density polyethylene, the low density polyethylene and the permanent antistatic agent included in the first layer and the third layer may range from 25 to 45: 25 to 45: 10 to 50 wt%. As the content of low-density polyethylene increases, that is, the lower the medium-density polyethylene content, the transparency and gloss increase, but the material becomes more flexible, that is, the stiffness is reduced, which is convenient for work. Sex may be reduced. In addition, as the content of the permanent antistatic agent increases, the antistatic effect is increased, but since the content of polyethylene is less, it may adversely affect the mechanical properties of the film. Therefore, when the weight ratio of the medium density polyethylene, the low density polyethylene, and the permanent antistatic agent contained in the first layer and the third layer is in the above range, there is an effect of optimizing the effect of improving workability and reducing scratches.

In the LCD protective film of the present invention, the weight ratio of medium or high density polyethylene and low density polyethylene included in the second layer may be in the range of 30 to 70:70 to 30 wt%. As the content of low-density polyethylene increases, that is, the lower the medium-density polyethylene content, the transparency and glossiness increase, but the softening of the material, that is, the effect of reducing the stiffness, resulting in convenience in operation This can be reduced. Therefore, when the weight ratio of medium or high density polyethylene and low density polyethylene included in the second layer is in the above range, there is an effect of optimizing the effect of improving workability and reducing scratches.

In the LCD protective film of the present invention, the thickness ratio of the first layer, the second layer and the third layer film may range from 20 to 30: 40 to 60: 20 to 30% of the total thickness of the LCD protective film. If the thickness ratio of the second layer is too low, the flexibility of the material is increased, the handleability is lowered. If the ratio is high, the transparency is lowered and excessive wrinkles may occur during extrusion, causing defects.

On the other hand, the LCD protective film of the present invention can be produced in a single process by a three-layer co-extrusion method. For example, the LCD protective film of the present invention as follows,

A first composition comprising medium density polyethylene, low density polyethylene and permanent antistatic agent, a second composition comprising medium or high density polyethylene and low density polyethylene, and a third composition comprising medium density polyethylene, low density polyethylene and permanent antistatic agent Preparing each; And it may be prepared by a method comprising the step of co-extruding the first to third compositions.

Co-extrusion refers to melting of multiple or homogeneous resins through a plurality of extruders to form a multi-layer molten state through a feedblock method or a multi-manifold method. After discharging into a furnace, the method of making a multilayer film through an extending process or a blowing process etc. is said. The coextrusion apparatus includes a plurality of extruder sections for melting and supplying resins having different characteristics, a plurality of supply pipe sections provided to supply a molten resin supplied from the extruder section, and a supply from the supply pipe section. It may be composed of a co-extrusion die unit 50 for receiving the melted resin is discharged in a sheet form. In the present invention, if the co-extrusion method known in the art is not particularly limited, preferably a three-layer blowing co-extrusion method can be used.

In general, polyethylene is very different from the characteristics of the product according to the conditions of the manufacturing process, in particular, density is the factor that most affects the properties of the polyethylene, according to the ASTM D1248 standard, polyethylene can be classified as follows.

Low Density Polyethylene (LDPE): Density 0.910-0.925

Medium Density Polyethylene (MDPE): Density 0.926-0.940

High Density Polyethylene (HDPE): Density above 0.941

As polyethylene density increases, yield point, tensile strength, softening point, chemical resistance, hardness and stiffness increase, but elongation, low temperature impact strength, environmental stress cracking and permeability decrease.

In the LCD protective film of the present invention, the high density polyethylene has a melt index of 0.04 ~ 5, the density of 0.941 or more, the medium density polyethylene has a melt index of 0.1 ~ 10, the density of 0.926 ~ 0.940, the low density polyethylene is a melt index 0.1-10 range, density 0.910-0.925 range.

In the LCD protective film of the present invention, the permanent antistatic agent is not particularly limited as long as it is used in the art, and non-limiting examples thereof include igastate (IRGASTAT, manufactured by Ciba Specialty Co.) P-18, P-16, P- 22 and the like.

In the LCD protective film of the present invention, a heat stabilizer may be added to the first layer and the third layer to prevent oxidation by heat, and the second layer together with the heat stabilizer may be processed by friction during extrusion. Lubricants and neutralizing agents can be added to prevent this from being reduced.

When the film is extruded, thermal oxidation may occur due to heat and friction of the extruder, which may be prevented by adding a small amount of a heat stabilizer. The heat stabilizer may be added in a range of 0.01 to 0.2 wt% based on the total weight of each layer. In the second layer, lubricants and neutralizing agents may be further added to increase workability. The lubricant and emulsifier may be added in a range of 0.01 to 0.03 wt% based on the total weight of the second layer. If the content of the heat stabilizer, lubricant and emulsifier is high, the material is flexible to reduce handleability, if the content is low, there is a problem that can cause contamination to the film by the implementation of the additive.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited thereto.

The experimental purpose of the following Examples and Comparative Examples is that the protective film of the present invention is environmentally friendly, simple to process, and low-cost manufacturing, while having the same or higher than the protective film of the comparative example or more than the film properties required in the industry It is intended to show that you can.

[Examples 1 to 5]

Using the composition described in Table 1 below, a three-layer extruded film was prepared. The three-layer extruded film was manufactured in one step without a separate lamination process and an antistatic coating process by using a three-layer blown film co-extrusion method.

The MDPE, HDPE, LDPE, and permanent antistatic agents used are as follows.

MDPE: DOW 5538 (0.8MI, 0.940) or

HDPE: Samsung F920A, or LG PM360

-LDPE: LG Chem BF315 or Samsung Petrochemical 432G

Permanent antistatic agent: Use one of BASF (P-16, P-18), DuPont (SD100, AS500), Sanyo (HOSTAT 2200), and Akema (PEBAX MV2080).

[Comparative Example]

As shown in Table 1 below, the outer layer film, the middle layer film and the inner layer film were each prepared by extrusion, and then a three-layer film was prepared through a separate lamination process (secondary dry lamination, dry lamination).

Example 1 Example 2 Example 3 Inner layer
30 μm MDPE 45t%
LDPE 25t%
Permanent Antistatic Agent
Compound 30wt% MDPE 45%
LDPE 25t%
Permanent Antistatic Agent
Compound 30wt% MDPE 45wt%
LDPE 25wt%
Permanent Antistatic Agent
Compound 30wt% Middle layer
40 μm MDPE 75wt%
Or (HDPE 75%)
LDPE 25wt% MDPE 75wt%
(Or HDPE75%)
LDPE 25wt% MDPE 75wt%
(Or 75% HDPE)
LDPE 25wt% Outer layer
30 μm MDPE 25wt%
LDPE 45wt%
Permanent Antistatic Agent
Compound 30wt% MDPE 25wt%
LDPE 45wt%
Permanent Antistatic Agent
Compound 30wt% MDPE 25wt%
LDPE 45wt%
Permanent Antistatic Agent
Compound 30wt% Example 4 Example 5 Comparative example Inner layer
20 ㎛ MDPE 45wt%
LDPE 25wt%
Permanent Antistatic Agent
30wt% MDPE 45wt%
LDPE 25wt%
Permanent Antistatic Agent
30wt% Inner layer: PE + permanent antistatic film (40㎛) Lamination Process (2nd Dry
Lamination) (5㎛) Middle layer
60㎛ MDPE 75wt%
Or (HDPE 75%)
LDPE 25wt% MDPE 75wt%
Or (HDPE 75%)
LDPE 25wt% Middle layer: PET (40㎛) Lamination Process: (Second Dry Lamination) (5㎛) Outer layer
20 ㎛ MDPE 45wt%
LDPE 25wt%
Permanent Antistatic Agent
Compound Compound 30wt% MDPE 45wt%
LDPE 25wt%
Permanent Antistatic Agent
Compound 30wt% Outer layer: PE + permanent antistatic film (40㎛)

The experimental results of the properties of the films prepared in Examples 1 to 5 and Comparative Example 1 are shown in Table 2 below.

The antistatic property was measured by the resistivity (Ω) of the film surface according to ASTM D 257-93, the stiffness of the film was tested by the film tactile.

Pol-dirty was determined by exposing each film to 700 lux of light at 60 ° C. and 75% humidity for 96 hours, then aging and then attaching it to the LCD screen This is the result of observing the surface state of the screen by putting the weight of the weight and giving a vibration to the film for a certain time.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example Antistatic property
(Ω) Less than 10 Less than 10 Less than 10 Less than 10 Less than 10 Less than 10 Film stiffness 5 6 5 7 7 7 Pol-dirty Great Great Great Great Great Good

The antistatic property was found to satisfy the level (10 ¹¹ Ω or less) required in the industry in both of Examples 1 to 5 and Comparative Examples.

In addition, film stiffness was also found that all of the Examples 1 to 5 and Comparative Examples satisfy the level required in the industry, and since the Film Stiffness of Examples 1 to 5 was smaller than that of Comparative Film, It is evaluated to reduce the occurrence of scratches on the LCD screen.

On the other hand, in the Pol-dirty category, it was found that the films of Examples 1 to 5 had superior characteristics to the films of the comparative examples.

As described above, the film of Examples 1 to 5 was found to have similar or better characteristics than the comparative example, and the thickness was thinner, and there is no additional post treatment, which is environmentally friendly, simple to process, and cheap material. It has been shown that there is an effect that can reduce the cost.

1: MDPE + LDPE + Permanent Antistatic Agent
2: MDPE (or HDPE) + LDPE
3: MDPE + LDPE + Permanent Antistatic Agent
4: antistatic (AS) coating
5: PET
6: PE + permanent antistatic agent
7: PET
8: PE + Permanent Antistatic Agent

Claims (8)

A first layer comprising medium density polyethylene, low density polyethylene, and a permanent antistatic agent; A second layer comprising medium or high density polyethylene and low density polyethylene; And a third layer including a medium density polyethylene, a low density polyethylene, and a permanent antistatic agent.
The LCD protective film according to claim 1, wherein the weight ratio of the medium density polyethylene, the low density polyethylene, and the permanent antistatic agent included in the first layer and the third layer is in the range of 25 to 45:25 to 45:10 to 50 wt%. .
The LCD protective film according to claim 1, wherein the weight ratio of medium or high density polyethylene and low density polyethylene included in the second layer is in the range of 30 to 70:70 to 30 wt%.
The film protective film according to claim 1, wherein the thickness ratio of the first layer, the second layer, and the third layer film is in the range of 20 to 30: 40 to 60: 20 to 30% of the total thickness of the LCD protective film.
The LCD protective film according to claim 1, wherein the film is extruded in a single process by a three-layer co-extrusion method.
The method of claim 1, wherein the high density polyethylene has a melt index of 0.04 ~ 5, the density is 0.941 or more, the medium density polyethylene has a melt index of 0.1 ~ 10 range, the density of 0.926 ~ 0.940, the low density polyethylene has a melt index of 0.1 ~ 10 LCD protective film, characterized in that the range, the density is in the range of 0.910 ~ 0.925.
According to claim 1, wherein the first layer and the third layer further comprises a heat stabilizer to prevent oxidation by heat, the second layer is a lubricant to prevent the processability is reduced by friction during the heat stabilizer and extrusion. And a neutralizer further comprising an LCD protective film.
A first composition comprising medium density polyethylene, low density polyethylene and permanent antistatic agent, a second composition comprising medium or high density polyethylene and low density polyethylene, and a third composition comprising medium density polyethylene, low density polyethylene and permanent antistatic agent Preparing each; And
Method of producing a protective film for the LCD comprising the co-extrusion of the first to third compositions.

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