PROTECTIVE FILM

Abstract

A protective film includes an adhesive layer containing a first synthetic resin, and a non-adhesive layer containing a second synthetic resin and micro-beads made of a polymer, the micro-beads being distributed in the second synthetic resin. The adhesive layer and the non-adhesive layer are laminated on each other.

Claims

1-6. (canceled)

7. A protective film comprising: an adhesive layer containing a first synthetic resin; and a non-adhesive layer containing a second synthetic resin and micro-beads made of a polymer, the micro-beads being distributed in the second synthetic resin, wherein the adhesive layer and the non-adhesive layer are laminated on each other, and wherein the non-adhesive layer has pores around the micro-beads.

8. The protective film of claim 7, wherein the polymer comprises a suspension polymer.

9. The protective film of claim 7, wherein a melting point of the micro-beads is higher than a melting point of the second synthetic resin.

10. The protective film of claim 7, wherein at least surfaces of the micro-beads are hydrophilic.

11. The protective film of claim 7, being a glass protective film used for protecting a glass plate, with the adhesive layer being stuck to the glass plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a view schematically showing a glass loading method of the related art;

[0024] FIG. 2 is a view schematically showing another glass loading method of the related art;

[0025] FIG. 3 is a view showing stains that may occur on glass in the glass loading method shown in FIG. 2;

[0026] FIG. 4 is a view showing contamination that is caused by fine dust in the process of manufacturing films;

[0027] FIG. 5 is a view showing an example of a functional protective film of the related art which is used in the loading method shown in FIG. 2;

[0028] FIG. 6 is a view showing another example of the functional protective film of the related art which is used in the loading method shown in FIG. 2;

[0029] FIG. 7 is a view showing a functional protective film according to an embodiment of the present invention;

[0030] FIG. 8 is a view showing a functional protective film according to another embodiment of the present invention; and

[0031] FIG. 9 to FIG. 11 views showing a variety of methods of laminating adhesive and non-adhesive layers according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below, so that a person having ordinary skill in the art to which the present invention relates can easily put the present invention into practice.

[0033] FIG. 7 is a view showing a functional protective film 340 according to an embodiment of the present invention.

[0034] The protective film 340 according to this embodiment includes at least two layers, i.e. an adhesive layer 341 and a non-adhesive layer 345, which are laminated on each other. The protective film 340 shown in FIG. 7 also includes an intermediate layer 343 which is situated between the adhesive layer 341 and the non-adhesive layer 345.

[0035] The protective film is typically used to protect a glass plate by being stuck to the glass plate. However, the present invention is not limited to this use. The adhesive layer of the protective film is stuck to the glass plate, and the non-adhesive layer is disposed opposite the adhesive layer.

[0036] The adhesive layer is typically stuck to the glass plate through self-adhesion, without an adhesive or bonding agent being interposed. However, the present invention is not limited thereto. The adhesive layer 341 contains a first synthetic resin. When the adhesive layer is a self-adhering adhesive layer, the first synthetic resin may be a polyolefin-based polymer, such as polyolefin, or a polymer produced through co-polymerization of an olefin-based monomer, such as ethylene vinyl acetate (EVA), ethylene acrylic acid (EAA) or ethylene methyl methacrylate (EMMA), and a monomer having a polar group. The first synthetic resin may also be one selected from among, but not limited to, a polyolefin-based rubber and other types of rubber.

[0037] Since the adhesive force of the self-adhering adhesive layer is limited or weak, when a strong adhesive force is required or the surface of a product to be protected is rough, it is possible to use an adhesive layer by applying an adhesive, such as an acrylic adhesive, to the surface thereof instead of the self-adhering adhesive layer. However, when an adhesive or bonding agent is used, the adhesive or bonding agent resides on the glass after the protective film is removed. Therefore, it is preferable to use a self-adhering adhesive layer.

[0038] The intermediate layer is typically made of polyethylene, and more preferably, low-density polyethylene.

[0039] The non-adhesive layer contains a second synthetic resin 345a and micro-beads 345b. The micro-beads 345b are distributed in the second synthetic resin. It is preferred that the melting point of the micro-beads be higher than the melting point of the second synthetic resin.

[0040] The non-adhesive layer of the protective film shown in FIG. 7 can be manufactured by the following process including the steps of: [0041] a) preparing micro-beads through polymerization; [0042] b) mixing the micro-beads into synthetic resin; and [0043] c) converting the mixture including the micro-beads and the synthetic resin into a lamellar structure.

[0044] In the a) step, polymeric micro-beads are prepared by mixing a monomer, a cross-linking agent and other additives into a polymeric stabilizer, followed by suspension polymerization. The resultant micro-beads are preferably cleaned and dried.

[0045] In the b) step, the micro-beads are uniformly mixed into the second synthetic resin using a single or twin screw extruder. After the micro-beads are mixed into the second synthetic resin and the mixture is extrusion-molded, a masterbatch can be made, and in the subsequent c) step, a non-adhesive layer having the lamellar structure can be molded by extruding the masterbatch.

[0046] The second synthetic resin may be implemented as a synthetic resin, the melting point of which is lower than the melting point of the micro-beads. For instance, the second synthetic resin may be implemented as one selected from among, but not limited to, i) polyethylene, ii) polypropylene and iii) polyolefin-based polymeric copolymers, and iv) polystyrene, v) polycarbonate, vi) polymethyl methacrylate and vii) acrylonitrile butadiene styrene-based copolymers.

[0047] The micro-beads can be implemented as micro-beads, the melting point of which is higher than the melting point of the second synthetic resin. It is preferred that the micro-beads be spherical. For instance, the micro-beads can be made of one selected from among, but not limited to, i) polyethylene, ii) polypropylene, iii) polymethyl methacrylate, iv) polystyrene, v) polyurethane and vi) cellulose acetate.

[0048] In the embodiment shown in FIG. 7, it is preferred that the micro-beads are hydrophobic. For example, hydrophobic micro-beads can be used or a hydrophobic functional group can be formed on the surface of micro-beads by surface-treating the micro-beads.

[0049] The multilayer structure including the adhesive layer and the non-adhesive layer can be produced in a variety of methods shown in FIG. 9 to FIG. 11.

[0050] First, as shown in FIG. 9, it is possible to form a polymer melt in which two or more layers are combined through co-extrusion of a raw material for the adhesive layer, i.e. the first synthetic resin, and a raw material for the non-adhesive layer made in the b) step (the mixture including the second synthetic resin and the micro-beads), cooling the resultant polymer melt, and then winding the cooled polymer melt.

[0051] Alternatively, as shown in FIG. 10, it is possible to manufacture a protective film by making a non-adhesive film in advance through the foregoing a) to c) steps separate from the adhesive layer and then extruding the first synthetic resin on the non-adhesive film.

[0052] In addition, as shown in FIG. 11, it is possible to manufacture a protective film by making an adhesive film from the first synthetic resin and then extruding the raw material for the non-adhesive layer (the mixture including the second synthetic resin and the micro-beads) on the adhesive film.

[0053] Although the extrusion was illustrated as an example of the lamellar processing, the present invention is not necessarily limited thereto.

[0054] FIG. 8 is a view showing a functional protective film according to another embodiment of the present invention.

[0055] A non-adhesive layer 445 of the protective film shown in FIG. 8 can be manufactured in a method similar to that of FIG. 7.

[0056] In contrast, in the a) step, micro-beads 445b are surface-treated, thereby generating a hydrophilic functional group ((OH, COOH, NH.sub.2) on the surface of the micro-beads 445b. Hydrophilic surface treatment can be precluded when hydrophilic micro-beads are used. The surface hydrophilicity of the micro-beads decreases affinity to a second synthetic resin 445a, thereby helping pores 445c form between the micro-beads and the second synthetic resin.

[0057] In addition, in the c) step, the non-adhesive layer that is molded into the lamellar structure is crystallized and then elongated, thereby forming pores around the micro-beads. Crystallization is influenced by the cooling speed. When the non-adhesive layer is crystallized more, elongation becomes difficult. However, this helps pores form since the affinity of the non-adhesive layer to the micro-beads is reduced. In contrast, when the non-adhesive layer is less crystallized, elongation becomes easy. However, it is difficult to form pores since the affinity of the non-adhesive layer to the micro-beads is increased. Therefore, it is important to realize elongation and affinity to micro-beads at required levels by controlling the degree of crystallization through adjustment of the cooling speed.

[0058] Reference numerals 441 and 443 respectively designate an adhesive layer and an intermediate layer.

[0059] The micro-beads on the non-adhesive layer shown in FIG. 5 and FIG. 6 are ground in the order of size through cold grinding (top-down processing). Therefore, the micro-beads shown in FIG. 5 and FIG. 6 have the problem of shape and size distribution control. In contrast, the micro-beads shown in FIG. 7 and FIG. 8 are polymerized in the reverse order of size so that smaller beads are synthesized before larger beads (bottom-up processing). Therefore, shape and size distribution control is easy for the micro-beads shown in FIGS. 7 and 8. (In particular, the micro-beads shown in FIGS. 7 and 8 can be included by only 20 wt % or less, whereas the content of the micro-beads shown in FIG. 6 ranges from 30 to 60 wt %.) In addition, the roughness of the film surface can be easily controlled. Furthermore, the micro-beads shown in FIG. 7 and FIG. 8 can be spherical. It is therefore possible to obtain the buffering effect to mechanical stress and prevent scratches. In particular, the non-adhesive layer shown in FIG. 8 is effective in buffering mechanical stress since it has pores therein.

[0060] The process of applying micro-beads on the non-adhesive layer shown in FIG. 5 is separate post-process. This consequently requires introduction of additional equipment such as a micro-bead injector and causes the problem of process environmental contamination due to fine dust of micro-bead. However, in case of FIG. 7 and FIG. 8, post-process is unnecessary step. Therefore, it is not required to introduce additional equipment, and there is no risk of process environmental contamination due to dust. In addition, since the micro-beads shown in FIG. 5 are exposed to the outside of synthetic resin, dust may be transferred to glass, thereby deteriorating the surface quality of the glass, which is problematic. In contrast, the micro-beads shown in FIG. 7 and FIG. 8 are present inside the second synthetic resin without causing dust transfer.

[0061] The foregoing descriptions of specific exemplary embodiments of the present invention have been presented with respect to the drawings. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible for a person having ordinary skill in the art in light of the above teachings.

[0062] It is intended therefore that the scope of the present invention not be limited to the foregoing embodiments, but be defined by the Claims appended hereto and their equivalents.