KR101316707B1 - Self-adhesive protection film for protecting light guide plate prepared by injection molding - Google Patents

Abstract

PURPOSE: A self-adhesive protective film is provided to prevent the contamination on a product by preventing the curling phenomenon of the end part of a film, to have excellent workability, and to prevent surface scratches when a light guide plate is manufactured. CONSTITUTION: A self-adhesive protective film (10) for protecting an injection light-guide plate comprises an outer layer (11) which includes a polypropylene and a blocking preventer; a medium layer (12) which includes a polypropylene; and an inner layer (13) including a metallocene ultralow density polyethylene and a metallocene linear low density polyethylene. The outer layer includes 85-95 wt% of the polypropylene and 5-15 wt% of the blocking preventer. The mixing weight ratio of the metallocene ultralow density polyethylene and the metallocene linear low density polyethylene in the inner layer is 95:5-10:90.

Description

Self-adhesive protective film for injection light guide plate {SELF-ADHESIVE PROTECTION FILM FOR PROTECTING LIGHT GUIDE PLATE PREPARED BY INJECTION MOLDING}

The present invention relates to a protective film, and more particularly, to a self-adhesive protective film for protecting an injection light guide plate that is used for a light guide plate of a display and curling does not occur at an end portion.

BACKGROUND ART Liquid crystal display (LCD) is widely applied in various fields such as computer monitors and mobile communication terminals due to advantages such as small size, light weight, and low power consumption.

A liquid crystal display (LCD) is a light receiving type element that itself does not emit light to form an image, and receives an external light to form an image. A liquid crystal display device (LCD) is a display element that allows an image to be observed even in a dark place by separately installing a light source. The backlight unit used in the liquid crystal display device is classified into a direct method and an edge light method according to the installation position of the light source. Among these, the edge light method is a method suitable for a display device requiring weight reduction and thickness reduction. In the backlight employing the edge light method, since the light sources are located at both ends, a light guide plate for uniformly inducing the linear light source generated from the light source to the lower part of the liquid crystal is required.

As a manufacturing method of such a light guide plate, a processing method of cutting a large area of a disc into a required area and a method of injection molding using a mold are known. In the manufacturing lines according to both manufacturing methods, a protective film for preventing damage to the light guide plate is provided. It is required.

For modern display products, cleanliness management is critical in the process to maintain a clean, clean screen from the time the product is produced and packaged to the final consumer. Protective films are also used to maintain the cleanliness and operating characteristics of the product surface.

Conventionally, as such a protective film, a protective film composed of an adhesive coating on polyethylene is used, but transparency is excellent, but fish eyes are poor, transfer characteristics are poor, and films are attached to each other. In addition, in order to form the adhesive coating, there is a problem in that a protective film is formed by overlapping a rubber layer or an acrylic adhesive layer on one surface of the substrate, or an additional process such as gravure coating or roll coating is performed to form a functional adhesive layer. .

Using a mixture of a propylene-based polymer and an ethylene-based polymer as a substrate, an adhesive layer was formed on the end face of the substrate, but in this case, there is a problem that a process of additionally coating the adhesive layer is required.

Moreover, a protective film may be formed using polypropylene resin as a base material layer and ethylene vinyl acetate copolymer resin (Ethylene Vinyl Acetate, EVA) as an adhesion layer. The film can be produced in a single process using a multilayer cast molding apparatus, but due to polar molecular groups such as vinyl acetate, dirt and foreign matters may adhere to the outer surface of the film, causing contamination.

Since the protective film is to be discarded after being used for a while in the process of manufacturing the light guide plate, a low cost film is required while meeting the requirements of the light guide plate protection film.

In addition, the light guide plate protective film may be attached to the light guide plate using an automatic packaging machine depending on the light guide plate manufacturing line, but the operator may manually attach the light guide plate to the light guide plate. In the case of manual packaging, when the protective film is cut to the size of the light guide plate, constant tension cannot be imparted, and thus the end of the film is curled before the cut protection film is attached to the light guide plate. In this case, in order to attach to the protective film, it is necessary to straighten the ends by applying a constant tension to the film, thereby causing a problem of deterioration and film workability.

The present invention solves the problems of the conventional products that the end is curled during manual packaging as described above, having a physical property of more than the level required as a light guide plate protective film, low cost, easy foreign material management, excellent self-adhesion for light guide plate protection excellent transfer characteristics. It is an object to provide a protective film.

The above object is an outer layer comprising a polypropylene and an antiblocking agent; A middle layer comprising polypropylene; And a metallocene ultra low density polyethylene, or an inner layer including metallocene ultra low density polyethylene and a metallocene linear low density polyethylene, which are formed by sequentially stacking, a self-adhesive protective film for protecting an injection light guide plate.

Preferably the outer layer comprises 85 to 95% by weight of polypropylene and 5 to 15% by weight of an antiblocking agent relative to the total weight of the outer layer.

Also preferably, the inner layer may include metallocene ultra low density polyethylene alone or mixed metallocene ultra low density polyethylene and metallocene linear low density polyethylene in a mixed weight ratio of 95: 5 to 10:90.

Also preferably, the antiblocking agent is at least one selected from the group consisting of silica, potassium carbonate and talc.

Also preferably, the protective film is based on the total thickness, the thickness ratio of the outer layer film is 10 to 30%, the thickness ratio of the middle layer film is 40 to 80%, the thickness ratio of the inner layer film is in the range of 10 to 30%.

Preferably, the protective film is extruded by a three-layer T-die cast extrusion method.

The self-adhesive protective film for protecting the injection light guide plate of the present invention does not generate curling phenomenon when the end of the film is curled during manual packaging, so that no contamination occurs in the product and the film workability is excellent. In addition, there is an advantage that the manufacturing cost is much cheaper while satisfying all the requirements of the protective film for the light guide plate. In addition, foreign matters are easy to manage, excellent transfer characteristics, and very soft to prevent surface scratches that may occur during manufacturing of the light guide plate, and has excellent slip performance of the outer layer (excellent workability).

1 is a cross-sectional view showing the structure of a self-adhesive protective film for protecting an injection light guide plate of the present invention.
2 exemplarily shows a coextruder used for general coextrusion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

Figure 1 schematically shows the structure of the self-adhesive protective film for protecting the injection light guide plate of the present invention.

The self-adhesive protective film 10 for protecting the light guide plate of the present invention includes an outer layer 11 including polypropylene and an antiblocking agent; A middle layer 12 comprising polypropylene; And an inner layer 13 including metallocene very low density polyethylene and metallocene lenier low density polyetylene.

The self-adhesive protective film for protecting the light guide plate according to the present invention is an outer layer made of polypropylene (PP) and an antiblocking agent, a middle layer made of polypropylene, a metallocene ultra low density polyethylene, or a metallocene ultra low density polyethylene and a metallocene linear low density polyethylene. Since the inner layer consists of a three-layer structure, the film is very soft compared to the conventional self-adhesive protective film for light guide plate protection, and the scratch of the light guide plate can be prevented. When applied to packaging, the ends of the cut film are not curled. In addition, since metallocene ultra low density polyethylene alone or metallocene ultra low density polyethylene and metallocene linear low density polyethylene are mixed at a predetermined ratio and used in the inner layer, the same or superior adhesive force as compared to a film using a conventional adhesive It does not generate any sticky stain on the surface of the light guide plate. The inner layer of the protective film may be a portion that is attached to the injection light guide plate.

In the self-adhesive protective film for protecting the light guide plate of the present invention, the polypropylene resin included in the outer layer is mainly composed of propylene as well as propylene homopolymer, and a small amount of ethylene, 1-butene, 1-hexene and 1-octene The propylene copolymer which copolymerized 1 or more types of alpha-olefins of 2, 4-20 carbon atoms, etc. is also included. In the case of a propylene copolymer, the content of monomers other than propylene may be 10 mol% or less. The polypropylene may be included in an amount of 85 to 95% by weight based on the weight of the outer layer.

The outer layer may further include an anti-blocking agent. At this time, the antiblocking agent may be added in 5 to 15% by weight. When the content of the antiblocking agent exceeds 15% by weight, there is a problem that the film transparency is lowered, when less than 5% by weight there is a problem that the film slip property is reduced. As the antiblocking agent, silica, potassium carbonate (CaCO ₃ ), talc, or the like can be used. More preferably, potassium carbonate can be used.

In the above, the middle layer may use polypropylene. In addition, the end of the cut film is not curled during manual packaging to use as a protective film for an injection light guide plate can improve the workability.

In the self-adhesive protective film for protecting the light guide plate of the present invention, the inner layer may contain a metallocene ultra low density polyethylene, or a metallocene ultra low density polyethylene and a linear low density metallocene polyethylene. When a mixture of metallocene ultra low density polyethylene and linear low density metallocene polyethylene is used, the weight ratio of metallocene ultra low density polyethylene (mVLDPE) and metallocene linear low density polyethylene (LLDPE) ranges from 95: 5 to 10:90. And preferably 90:10 to 50:50.

Metallocene ultra low density polyethylene is polyethylene polymerized using a single active site catalyst such as metallocene, and has a uniform structure compared to polyethylene produced by a conventional Ziegler-Natta catalyst. Metallocene ultra-low density polyethylene is excellent in adhesion because the structure is uniform and the polymer chains are tightly entangled and sewn together, thereby providing self-adhesiveness.

When the content of the metallocene ultra low density polyethylene of the components constituting the inner layer is excessive, the adhesiveness is excellent, but when the film is left at high temperature, the films adhere to each other at low temperatures due to low melting point, resulting in poor peeling properties between the films. In the case of a small amount, the heat resistance is increased, but the adhesive strength is too weak, the adhesion between the films is poor, and there is a problem of having almost no self-adhesiveness for protecting the light guide plate. In another aspect, the present invention is characterized by using a metallocene ultra low density polyethylene and a metallocene linear low density polyethylene mixed in the above range in the inner layer. The present invention is used by mixing with ultra-low density metallocene polyethylene and metallocene linear low-density polyethylene, to enhance the adhesive strength of the inner layer, and after passing the high temperature process of about 80 ℃ generated during transport after attaching the film to the light guide plate, When removed, the film has excellent peeling properties, and no foreign matter or adhesive stains are generated on the light guide plate surface.

Due to the difference in density between the outer and inner layers of the film, shrinkage occurs in repulsion when the film is stretched, and curling phenomenon occurs in which the end of the film is curled. In the present invention, by adjusting the composition of the outer layer and the inner layer to make their density gradient the same, it is possible to completely improve the curling characteristics during product production.

In the self-adhesive protective film for light guide plate protection of the present invention, the thickness ratio of the outer layer, the middle layer and the inner layer film may range from 10 to 40:80 to 20:10 to 40 with respect to the total thickness of the self-adhesive film for light guide plate protection.

On the other hand, the self-adhesive protective film for light guide plate protection of the present invention can be produced by a three-layer T-die cast co-extrusion method with a fine filter attached.

Co-extrusion refers to melting dissimilar or homogeneous materials through a plurality of extruders and discharging them in a multi-layer molten state through a feedblock method or a multi-manifold method. After that, a method of making a multilayer film through a stretching process, a blowing process, or a cast process. 2 exemplarily shows a coextrusion apparatus 20 used for coextrusion. The coextrusion apparatus 20 includes a plurality of extruder portions 21 for melting and supplying resins having different characteristics and a plurality of supply pipe portions provided to supply resin in a molten state from the extruder portion 21. And a coextrusion die portion 22 which receives molten resin from the supply pipe portion and discharges the molten resin into a sheet shape. In the present invention, the co-extrusion method known in the art is not particularly limited, but preferably a three-layer T-die cast co-extrusion method may be used, and in particular, an extruder with a fine filter may be used. The fine filter may be a disc type, a leaf disc type, a wirenet type, and a filter reinforced with a mesh on one side or both sides may be used.

Specifically, the melt which melt | dissolved the resin composition which comprises an outer layer or an inner layer can be coextruded from a T-die to a film form, respectively, and can go through the process of cooling by a cooling roll.

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 has the same or higher than the protective film of the comparative example or more than the film properties required in the industry, the process is simple and can be manufactured at low cost It is to be seen.

Example  1 to 5

Using the composition shown in Table 1 below, a 40-micrometer-thick three-layer extruded film was prepared. The three-layer extruded film was produced using a three-layer T-die cast extrustion method.

As the polypropylene (pp) resin used in the outer and middle layers, Honam Petrochemical's FC150B product was used. The inner layer of metallocene ultra low density polyethylene (mVLDPE) resin was ExxonMobil Exact0203 or Japan JPE's KF360 and DOW's PL1880,1850. Was used.

On the other hand, potassium carbonate was used as the anti-blocking agent used for the outer layer, which serves to impart slip properties to the film.

Comparative Example  One

With the composition shown in Table 1 below, the PE film was extruded, and then coated on one surface of the film with an acrylic adhesive, followed by drying.

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.

Adhesion was measured by KSA 1107 method (g / 25mm, 90 ° PEEL).

The static electricity generation characteristics were measured for the resistivity (Ω) of the film surface according to ASTM D 257-93.

The number of fisheye and sticky stains were visually observed.

Heat resistance temperature during film adhesion was evaluated relative to the peeling force evaluation after aging for 72 hours by temperature.

The end curling characteristics subjectively determined the end curling characteristics when cutting to the size used in the light guide plate using a manual packaging machine.

The STOP LINE of the film was attached to the PMMA sheet at a temperature between 60 and 90 ℃, and after leaving it for a certain period of time, it was visually observed whether or not the STOP LINE occurred in the line where it stopped. Observed and evaluated as.

Adhesion was evaluated that the films of Examples 1 and 3 were generally superior to the films of Comparative Example 1. In addition, the fish eye, the static electricity generation characteristics, tacky stains, the adhesion between the films was very excellent in the films prepared in Examples 1 to 5. In addition, the protective film for an injection light guide plate of the present invention can be seen that the end curling phenomenon during manual packaging is very excellent, within 5mm.

As described above, the film of Examples 1 to 5 was shown to have more excellent properties than the comparative example, and it was shown that the cost can be reduced by using a cheap material.

10: Light guide plate protective film
11: outer layer
12: middle floor
13: inner layer
20: coextrusion apparatus
21: extruder
22: coextrusion die part
23: 3-layer film

Claims (6)

An outer layer comprising polypropylene and an antiblocking agent; A middle layer comprising polypropylene; And inner layers comprising metallocene ultra low density polyethylene and metallocene linear low density polyethylene are sequentially stacked,
The outer layer comprises 85 to 95% by weight of polypropylene and 5 to 15% by weight of antiblocking agent, based on the total weight of the outer layer,
The inner layer of the self-adhesive protective film for injection light guide plate protection, characterized in that the metallocene ultra low density polyethylene and metallocene linear low density polyethylene is mixed in a mixed weight ratio of 95: 5 to 10:90. delete delete The self-adhesive protective film of claim 1, wherein the antiblocking agent is at least one selected from the group consisting of silica, potassium carbonate, and talc. According to claim 1, wherein the protective film is based on the total thickness, the outer layer film 10 to 40%, the middle layer film 40 to 80%, the inner layer film 10 to 40% of the self-adhesive protection for injection light guide plate protection, characterized in that. film. The self-adhesive protective film of claim 1, wherein the protective film is extruded by a three-layer T-die cast extrusion method.

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