KR20010098335A - Surface-protecting film - Google Patents

Abstract

(Problem) Provides a surface protection film which can prevent sticking of sheets upon stacking due to bulging of the adhesive of an optical sheet such as a polarizing plate, and at the same time can easily remove foreign substances adhering to the surface. .

(Solution means) The release film 5 stuck to one side of the base material 3 of the protective film A used for optical sheets, such as a polarizing plate, through the adhesive 4, and the base material 3 On the other side of the surface, a silicon acrylate-based comb graft polymer layer 2 coated with an antistatic agent layer is provided, and the silicone acrylate-based comb graft polymer layer is 3 to 10 mg / m as a solid. Coating ²

Description

Surface Protective Film {SURFACE-PROTECTING FILM}

This invention is surface protection used for the protection at the time of processing and mounting, such as a polarizing plate used for display screens, such as a computer, a liquid crystal television, a car navigator, a mobile phone, etc., for example. It is about a film.

At the time of processing and mounting of optical sheets such as polarizing plates, a surface protective film for preventing the image and contamination of the sheet is affixed, the adhesive is applied to the back surface and dried, and the release film is combined. Next, it is common to trim and preserve | stack and preserve | stack according to the target polarization angle.

When affixing to the said display screen, heat processing, such as an autoclave, may be performed, and the surface protection film needs to have heat resistance which heat shrinkage does not produce.

In addition, the polarizing film which affixed the protective film at the time of lamination | storage preservation may prevent the adhesive for affixing at the time of mounting, to smear the surface by protruding from an edge part, etc., and to prevent external inspection work or sticking. .

Since the adhesive adhering to the surface of this protective film is regarded as a defect of the optical sheet itself, it is wiped off with organic solvents, such as alcohol, ester, and ketones. Alternatively, the deposit is brushed off with water.

The synthetic resin film which originally becomes the base material of a surface protection film does not have mold release property with respect to the adhesive which protruded.

If necessary, water-soluble antistatic agents such as quaternary ammonium salts and polyhydric alcohol derivatives are internally added or surface coated in order to avoid static interference during mounting in the present application. Although an engineered film is used, these antistatic agents can be dissolved in water, alcohol, and the like used for removing the above contaminants, and fall off in this washing process to lower the antistatic effect.

In order to prevent the removal of the pressure-sensitive adhesive and the antistatic agent falling off from the back protective film, a long-chain alkylcarbamate-based non-silicone release agent or a silicone release agent is coated. Although attempts have been made, the release agent of the long-chain alkylcarbamate system is insufficient in releasability and cannot be easily removed.

In addition, the silicone release agent is easy to remove due to releasability.However, by applying a cellophane adhesive tape to the surface protection film, the surface protection film is pulled up by the adhesiveness of the adhesive tape. none. Had various problems.

The present invention has been made to solve the above problems, the release film adhered to one side of the base material of the protective film used for the optical sheet such as polarizing plate, through the pressure-sensitive adhesive layer, and the antistatic agent layer on the other side of the base material The silicone acrylate-based comb graft polymer layer coated with the through-coating layer, wherein the silicone acrylate-based comb graft polymer layer is coated with 3 to 10 mg / m ² as a solid content, thereby providing an optical sheet adhesive such as a polarizing plate. It is an object of the present invention to provide a surface protection film which can prevent sticking of sheets when they are stacked by deviating, and can easily remove foreign substances adhering to the surface.

In other words, one of the characteristics of the protective film of an optical sheet, such as the polarizing plate of this invention, is that the outer layer of a protective film makes it difficult to adhere | attach a foreign material, and the contact angle of water which is easy to remove washing water etc. It is characterized by having water repellency of 80 degrees or more.

Another characteristic as a protective film of the optical sheet such as a polarizing plate of the present invention without being, the antistatic function, which is given in advance to the synthetic resin film protective film substrate, the loss in the impurity removal process, such as clearance by water washing and wiping, 10 ¹⁰ Ω /? It is characterized by having an electrical characteristic that maintains the following surface resistance value, and prevents the occurrence of trouble due to static electricity in the adherend.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which expands and shows a part of surface protection film of one Example which concerns on this invention.

2 is an enlarged cross-sectional view of a part of a conventional surface protection film.

* Explanation of symbols for the main parts of the drawings

1: silicone acrylate comb graft polymer

2: antistatic agent layer 3: base material

4: adhesive layer 5: release film

Means of the present invention for achieving the above object,

A release film adhered to one side of the base of the protective film used for an optical sheet such as a polarizing plate through an adhesive layer, and a silicon acrylate-based comb graft polymer layer coated on the other side of the base through an antistatic agent layer. Equipped,

The silicone acrylate-based comb graft polymer layer is in the configuration of a surface protective film coated with 3 to 10 mg / m ² as a solid content.

In addition,

The peeling film uses the tape using an acrylic adhesive, and is formed so that the peeling strength of one side of this peeling film may be less than 1 N / 25 mm.

Also,

The contact angle of water to the other side of the substrate has water repellency of 80 degrees or more.

The base material of a surface protection film is a biaxially stretched polyethylene terephthalate film, and the thickness of the base material uses 16-50 micrometers.

The pressure-sensitive adhesive layer is coated with a two-liquid curable acrylic pressure-sensitive adhesive as a solid content of 10 to 30 g / m ² e, and a peel resistance value is obtained in a stainless steel adherent plate specified in JIS Z-2037 (adhesive tape test method). It is made by coating a re-peelable pressure-sensitive adhesive having a thickness of 0.05 to 0.5 N / 25 mm.

A release sheet made of synthetic resin is an adhesive door and a wound on the pressure-sensitive adhesive layer of the surface protective film.

Next, an example of implementation of the surface protection film which concerns on this invention is demonstrated based on drawing. 1: is an example which expands and cross-sections a part of surface protection film A of an Example of this invention.

This surface protection film (A) is employ | adopted for the optical sheet used for the display screen of a personal computer, a liquid crystal TV, a car navigator, a mobile telephone, for example, and is a surface protection film (A) affixed on this polarizing plate etc. This foreign matter such as an adhesive adhered at the time of mounting is easily wiped off, and is removed by hot water washing or the like, and the antistatic agent given to the surface protection film (A) in advance is removed by these wiping or hot water cleaning. There is no work, and a protective film having peelability and water repellency is formed, and the antistatic function can be maintained even when friction and washing in alcohol or hot water.

The surface protective film (A) is coated with a re-peelable two-liquid curable acrylic pressure-sensitive adhesive (4) on one side of the base material (3) such as an antistatic synthetic resin film, and the release film (6) is attached thereto. On the other side (back) of the base material 3, the comb-grafted graft polymer layer 1 composed of an acrylic polymer and a branch part of a silicone macromonomer is coated with an antistatic agent layer 2 by coating. Formed.

Moreover, although the base material 3, such as said synthetic resin film, is used the film etc. which use polyethylene, a polypropylene, polyester, a polyimide, etc. as a raw material, for example, are biaxially stretched in consideration of the heat resistance at the time of use, among others, One polyethylene terephthalate film is preferred.

As for the film thickness of the base material 3, about 16 micrometers-50 micrometers in thickness, Preferably 25 micrometers-38 micrometers in thickness are suitable. This is because the thickness of the film of the base material 3 is too thin for a film having a thickness of less than 16 μm, which makes it difficult to protect the polarizing plate due to scratches or the like caused by protrusions from the outside. Becomes difficult.

In addition, if the thickness exceeds 50 µm, the rigidity is excessive and it is difficult to affix uniformly without floating. The cost structure of the protective film increases the cost of the original film that occupies the placenta, resulting in an economical requirement for the protective film. There is a difficulty.

In addition, the comb graft polymer 1 coated on the other side may be cured by adding an isocyanate-based reactant or may be an additive without a curing agent to react.

In the case where the silicone acrylate-based comb graft polymer layer 1 as the protective film used in the embodiment of the present invention uses a charging layer, why does not inhibit the antistatic performance of the antistatic agent layer 2 in the lower layer. In addition, the performance is maintained even if excessive treatment such as water washing is performed. Although the theory is not explained, the coating amount is a very small amount of 3 to 10 mg / m ² , and the insulating layer is formed on the antistatic layer 2. Even if a thin film is provided, it is described in Patent Publication No. 2939431 and the like that the thin film does not inhibit the effect.

In addition, if the coating amount of the silicone acrylate-based comb graft polymer layer 1 is less than 3 mg / m ² , the film thickness formed is weak, and it cannot cope with washing with friction and water. And dropping together with the lower layer of the antistatic agent, raises the surface resistance value, causing an unreasonable occurrence of electrical failure during mounting.

If the coating amount exceeds 10 mg / m ² , the function of the lower antistatic agent is inhibited, and the surface resistance is high, which is not preferable.

Moreover, since this comb graft polymer 1 has a high glass transition point of 60 to 180 degreeC and the branch part of the said comb graft polymer 1 consists of silicone, it is water-repellent and inclined. The coefficient of static friction by the type friction measuring instrument is 0.2 to 0.4, which has a moderate slipperiness and a sufficient film strength, so that it is easy to match when stacked.

On the other side of the re-peelable two-liquid curable acrylic pressure-sensitive adhesive (4), a silicone-based release agent (5a) is applied to the release film (5) made of biaxially stretched polyester or polyethylene terephthalate film (5b). It is attached.

That is, this peeling film 5 is affixed on the surface protection film A, and is formed in roll shape wound by the cylindrical shape.

In addition, the said peeling film 5 uses the tape using an acrylic adhesive, and is formed so that the peeling strength of one side (back surface) of the said peeling film 5 may be less than 1 N / 25mm.

In this peeling film 5, when the peeling strength by the tape using an acrylic pressure sensitive adhesive tape is 1 N / 25 mm or more, the adhesive which protrudes when it cuts and piles on a flat plate, adheres to the surface, a polarizing plate, etc. It is regarded as a defect of the optical sheet itself, or causes troubles to stick together. In addition, the adhered adhesive is hard to be wiped off by an organic solvent or the like, and remains stolen.

In addition, when the peeling strength is less than 1 N / 25 mm, the protruding pressure-sensitive adhesive is difficult to adhere, and even when attached, it can be easily removed with an organic solvent and no stolen traces remain.

Moreover, the contact angle of the water to the other side of the base material 3 is 80 degree or more, Preferably it has 90 or more water repellency.

When this contact angle is less than 80 degrees, water becomes easy to get wet on the back surface, and water is easy to generate | occur | produce on the surface by water adhesion after water washing for the back dirt removal, and when there is an antistatic agent in the lower layer, It is preferable to have a contact angle of 90 degrees or more, because the lower antistatic agent in all exempts dissolves in water and causes a decrease in antistatic function.

The pressure-sensitive adhesive layer 4 provided on one side of the base material 3 is coated with a two-liquid curable acrylic pressure-sensitive adhesive 10 to 30 g / m ² as a solid content, and is made of stainless steel as defined in JIS Z-2037 (adhesive tape test method). In a board | plate, the peeling resistance value is 0.05-0.5 N / 25 mm, Preferably it is made by coating the peelable adhesive which is 0.1-0.3 N / 25 mm.

If the coating amount of the adhesive is less than 10 g / m ² , if there are irregularities of the adherend, it cannot be adhered for 10 minutes, and it rises, and it fails to function as a protective film. The complex may be bent or the removal efficiency may be deteriorated.

(Example 1)

2-ethylhexyl acrylate / methyl methacrylate on one side of the biaxially stretched polyethylene terephthalate film (3) having a thickness of 38 µm in which a quaternary ammonium salt (2) was added 0.05 g / m ² to the surface as an antistatic agent. Each monomer of / vinyl acetate / hydroxyethyl methacrylate / acrylic acid was blended in a 40/40/16/1/3 ratio by weight, and the catalyst was prepared using 2. 2'-azobis-isobutylonitrile and nitrogen streams. Then, a re-peelable acrylic pressure-sensitive adhesive having a polymerization degree Mw of 70 to 800,000 and a solid content of 30%, obtained by polymerization in ethyl acetate was blended at 100: 3 in a weight ratio of colonnade L, and coated with 20 g / m ^{2 in} solid content, It dries at 80 degreeC for 5 minutes.

On the other side, the stem part is an acrylic polymer and the branch part is composed of a silicone macromonomer that occupies 30% to 40% of the total, and a comb-type graft polymer having a molecular weight of 20 to 300,000 (Toagosei's product name 'Simak SYMAC US- 270 ") (1) as a solid content, 5 mg / m <^2> coating, and it is made to dry at 100 degreeC for 5 second, and a complete fusion | melting coating is made.

Next, it bonds with the peeling film 5 based on the biaxially-stretched polyester 5b of 25 micrometer thickness formed by coating the silicone type mold release agent 5a, and the surface protection film A of a wound shape. Got.

(Example 2)

In the same manner as in Example 1, on the one side of the biaxially stretched polyethylene terephthalate film 3 having a thickness of 38 µm in which a quaternary ammonium salt (1) was added 0.05 g / m ^{2 to} the surface, The same pressure-sensitive adhesive is coated, and on the other side, the stem portion is an acrylic polymer and the branch portion is composed of a silicon macromonomer that occupies 20% to 30% of the total, and a comb-type graft polymer having a weight of 200,000 to 300,000 (Toagosei Corp. 5 mg / m <^2> is applied by making a product name "Sifilm SYMAC US-352") (1) into solid content, it is made to dry at 120 degreeC for 5 second, and a complete fusion film is formed.

Next, it bonds with the peeling film 5 based on 25 micro-thick biaxially-stretched polyester 5b formed by coating the silicone type mold release agent 5a, and the surface protection film A of a wound shape. Got.

(Comparative Example 1) Fig. 2 (a)

Except that the comb graft polymer or the like was not coated on the 38-micron-thick biaxially stretched polyethylene terephthalate film 3 having a quaternary ammonium salt (2) added 0.05 g / m ² to the surface as an antistatic agent, The surface protection film A1 which carried out the adhesive processing similar to the said Example 1 was created.

Comparative Example 2 FIG. 2 (b)

The same treatment as in Example 1 was carried out except that the comb graft polymer 1a having a glass transition point of 60 ° C (manufactured by Toagosei Co., Ltd., `` Simak SYMAC US-270 '') was coated with 1 mg / m ² as a solid content. The implemented surface protection film (A2) was applied.

Comparative Example 3 FIG. 2C

The same treatment as in Example 1 was performed except that 1 mg / m ^{2 was} coated using a comb-grafted graft polymer 1b (trade name "Simak SYMAC US-352" manufactured by Toagosei Co., Ltd.) at 180 ° C as a solid content. Surface protection film (A3) was applied.

Comparative Example 4 FIG. 2D

A surface protective film (A4) subjected to the same treatment as in Example 1 was prepared except that a long-chain alkylcarbamate-based release agent (6) ("Biloyl 1010" manufactured by Ibosha Co., Ltd.) was used as the back release agent.

Comparative Example 5 FIG. 2E

As a back mold release agent, the surface protection film (A5) which performed the process similar to the said Example 1 except that the reactive silicone type mold release agent (7) normally used for a peeling film was used.

The result at the time of affixing the surface protection film (A, A1-A5) created by Example 1, Example 2, and Comparative Examples 1-5 to the optical sheet (in this case, a polarizing plate) is shown in later Table 1 .

That is, when the release agent was not applied on the antistatic layer of Comparative Example 1, the slipperiness (static friction coefficient) is poor, and it can be easily inferred that blocking will occur if the polarizing plate affixing the surface protective film is cut and laminated. When foreign matters such as sticking out of the adhesive adhered to the back surface, the antistatic agent was eluted by friction in water as a removal method, causing the generation of static electricity.

As shown in Comparative Examples 2 and 3, even when the adhesion amount of the silicone acrylate comb graft polymer as a release agent is small at 0.1 g / m ² , the water repellency is lowered, although not as extreme as in the case of uncoated steel. Foreign substances, such as an adhesive, were not removed completely, and also antistatic ability fell.

In the case of the so-called non-silicone mold release agent based on the long-chain alkyl group used in Comparative Example 4, the initial foreign matter adhesion prevention ability and water repellency were relatively good, but when rubbed for removing foreign matter under water, water repellency was really lost. At the same time, the back resistance increased.

This is inferred to be due to insufficient coating strength and adhesion of the release agent, and thus the coating was dropped and the lower layer of antistatic agent was retained.

In the case of using the curable silicone, which is a release agent for film of Comparative Example 5, both the foreign matter adhesion ability and the water repellency after water washing are good, but the performance of the antistatic agent in the lower layer than the original physical properties of the silicone resin is not exhibited. There is a flaw.

On the other hand, the surface protection arm of the Example of this invention created by Examples 1 and 2 was excellent in the foreign matter adhesion prevention property in the initial stage of scientific sheet sticking, and after water washing, and also stuck firmly to the surface. Even after washing with an adhesive or the like, the film does not fall off, and as a result, the antistatic agent is not retained. Therefore, the static electricity is generated to attract or stick dust during lamination of the optical sheet. It has been found that it can prevent causing problems that do not come off.

Yes Example Comparative Example One 2 One 2 3 4 5 Release Agent on Antistatic Layer US-270 * US-352 ** - US-270 * US-352 ** Be Royle 1010 Peeling silicon Coating amount (mg / m2 solid) 5 5 - One 5 5 Static friction coefficient (tanθ =) * 1) 0.2 0.33 0.42 0.3 0.35 0.26 0.15 Slip Good Good Slip Good Good Good Slippery Foreign body adhesion ※ 2) No attachment No attachment Adhesion contamination Not attached Not attached Small attachment No attachment Surface water repellency State Fried Bun Fried Bun Front wet Fried slowly Fried slowly Deep fried tempura Fried Bun After underwater friction Fried Bun Fried Bun Wetting Wetting Wetting Front wet Fried Bun Contact angle (°) condition 105 105 45 95 95 95 105 After underwater friction 90 90 55 75 75 50 105 Antistatic condition 108 108 108 108 108 108 1012 After underwater friction 1010 1010 1012 1012 1012 1012 1012 Acrylic paste to release side Peel force to tape (N / 24 mm) ※ 3) 0.2 0.4 8.0 1.0 1.3 2.2 0.04 Rubber-based paste to the release surface Peel force to tape (N / 24 mm) ※ 4) 2.0 3.5 7.5 3.5 4.0 4.0 0.05 Adhesion ※ 5) (N / 25mm) Stand SUS 0.13 0.13 0.13 0.13 0.13 0.13 0.1 Stand polarizer 0.1 0.1 0.1 0.1 0.1 0.1 0.09 US270 *; Comb consisting of acrylic polymer with stem part and silicone macromonomer with branch part Polymer, silicone having a graft rate of 30 to 40% and molecular weight (W) of 20 to 30 All-release agent (Saimak STMAC US-270, manufactured by Toagosei Corporation). US352 **; Comb pole consisting of acrylic polymer with stem part and silicone macromonomer with branch part Reamer, silicone with graft rate of 20-30%, molecular weight (W) 20-300,000 Phosphorus Release Agent (Saimak STMAC US-352, manufactured by Toagosei Co., Ltd.). ※ 1) PET pain and release treatment surface ※ 2) Laminating and cutting 10 sheets of release protective film with release treatment, and rub the end face 5 times on the back of the protective film. Therefore, visually confirm the transfer and electrodeposition of the adhesive. ※ 3) Nitto Denko 31B tape * 4) Commercial cellophane tape * 5) Peel resistance from the adherend at tensile speed 300 mm / min according to JIS-Z-0237

According to the present invention constituted as described above, by using the surface protective film according to the present invention, a pressure-sensitive adhesive for mounting is protruded upon cutting and laminating storage in a predetermined dimension, and a protective film. The surface contamination can be reduced, and it is possible to greatly reduce the misunderstanding caused by defects in the optical sheet itself, which is an adherend, and to rub and clean the dead adhesives in water or alcohol. Even if the silicon-acrylic comb graft polymer layer of the surface layer becomes a protective wall, the antistatic layer in the case of using the lower antistatic layer is not lost.

As a result, an antifouling or antistatic function is maintained, and the unique effect of being able to improve productivity of a polarizing plate etc. is exhibited.

Claims (6)

A release film affixed on one side of the base of the protective film used for an optical sheet such as a polarizing plate through an adhesive layer, and a silicon acrylate-based comb graft polymer layer coated on the other side of the base through an antistatic agent layer; With The silicon acrylate-based comb graft polymer layer is a surface protective film, characterized in that 3 to 10 mg / m ² is coated as a solid content. The method of claim 1, The peeling film uses the tape using an acrylic adhesive, The surface protection film characterized in that it was formed so that peeling strength of one side of this peeling film might be less than 1 N / 25mm. The method of claim 1, Surface contact film, characterized in that the contact angle of water to the other side of the substrate has water repellency of 80 degrees or more. The method of claim 1, The base material of a surface protection film is a biaxially stretched polyethylene terephthalate film, The thickness of the base material is 16-50 micrometers, The surface protection film characterized by the above-mentioned. The method of claim 1, The pressure-sensitive adhesive layer is coated with a two-liquid curable acrylic pressure-sensitive adhesive as a solid content of 10 to 30 g / m ² e, and the peel resistance value is 0.05 to 0.5 N / in a stainless steel adherent plate specified in JIS Z-2037 (adhesive tape test method). A surface protective film, which is formed by coating a 25 mm re-peelable pressure-sensitive adhesive. The method of claim 1, A peeling sheet made of synthetic resin is stuck to the pressure-sensitive adhesive layer of the surface protective film, and the sheet is wound.