JPH11256116A - Surface-protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transparent surface-protective film with slight electrification when peeled off, having a combination of anti-staining effect and antistatic effect, by providing one side of a plastic film with a layer containing an antistatic ingredient and anti-staining ingredient and providing the opposite side with a slight-tack layer. SOLUTION: This surface-protective film is obtained by providing one side of a plastic film (highly transparent, e.g. a polyester film such as of polyethylene terephthalate or pclyethylene-2,6-naphthalate, also pref. a biaxially oriented film) with a layer containing an antistatic ingredient (e.g. an antistatic agent such as a quaternary amjnonium salt) and an anti-staining ingredient (e.g. polyvinyl alcohol) and providing the opposite side with a slight-tack layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protective film, and more particularly to a surface protective film based on a polyester film, which is transparent, has low friction and little electrification when peeled off, and has a stain on the surface. The present invention relates to a surface protective film that is difficult to adhere.

[0002]

2. Description of the Related Art A transparent protective film such as polyethylene or polypropylene is laminated on the surface of various displays such as a word processor, a computer or a television, or an optical component such as a polarizing plate or a laminate similar thereto, for the purpose of surface protection. ing. After the installation of the liquid crystal display etc. is completed,
These protective films are often removed by peeling, but there is a problem in that static electricity is generated at the time of peeling, and surrounding dust is involved.

In particular, in recent years, in a liquid crystal display of a TFT system corresponding to high definition, there is a problem that a TFT element is destroyed by peeling charging when a protective film is peeled.

On the other hand, conventional transparent protective films such as polyethylene and polypropylene are inferior in transparency, and when a defect inspection is performed on a product after a display is incorporated, the transparency of the protective film is inferior. In addition, it has been difficult to perform the defect inspection with high accuracy.

[0005] In order to increase the transparency of the protective film, it is conceivable to use a laminated film based on a highly transparent polyethylene terephthalate film. For example, the protective film was laminated to a polarizing plate and cut. In this case, there is a problem that the pressure-sensitive adhesive protrudes from the cut surface and adheres to the surface of the protective film when the polarizing plates are overlapped, which hinders a defect inspection of the product.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, to be transparent, to have little peeling charge when used for a surface protective film of various displays, and to be used for a polarizing plate or the like. It is an object of the present invention to provide a surface protective film having both a dirt prevention effect and an antistatic effect when exposed, and which does not hinder a defect inspection of a product.

[0007]

According to the present invention, a plastic film is provided with a layer containing an antistatic component and an antifouling component on one side, and a fine layer on the other side. This is achieved by a surface protective film characterized by providing an adhesive layer.

Hereinafter, the present invention will be described specifically. The plastic film in the present invention is a film having high transparency, and examples thereof include a polyester film, a polycarbonate film, a triacetyl cellulose film, a polypropylene film, and a polyethylene film. Among these, a polyester film excellent in productivity and processability is preferable. As the polyester film, either a uniaxially oriented film or a biaxially oriented film can be used, but it is preferable to use a biaxially oriented film.

The polyester constituting the polyester film is a linear polyester obtained by polycondensing a dicarboxylic acid component and a glycol component. As dicarboxylic acid components, terephthalic acid, isophthalic acid, 2,2
6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4.4'-diphenyldicarboxylic acid, adipic acid,
Sebacic acid, dodecanedicarboxylic acid and the like can be exemplified.
In particular, terephthalic acid, 2,
6-Naphthalenedicarboxylic acid is preferred.

The glycol component includes ethylene glycol, diethylene glycol, propylene glycol,
1,3-propanediol, 1,4-butanediol,
Neopentyl glycol, 1,6-hexanediol,
Examples include cyclohexane dimethanol, polyethylene glycol and the like. Particularly, ethylene glycol is preferred from the viewpoint of the rigidity of the film.

The above-mentioned polyester may be a copolyester obtained by copolymerizing the above-mentioned dicarboxylic acid component or glycol component as the third component, or may contain a trifunctional or higher polycarboxylic acid component or a polyol component.
A polyester obtained by copolymerizing a small amount in a range where the obtained polyester is substantially linear (for example, 5 mol% or less) may be used.

As the polyester, polyethylene terephthalate or polyethylene 2,6-naphthalate is particularly preferred.

Such a polyester can be prepared by a conventional method. If the intrinsic viscosity of the polyester (in ortho-chlorophenol, at 35 ° C.) is 0.45 or more, the mechanical properties such as high rigidity of the film are improved. Therefore, it is preferable. The polyester includes silicon oxide, aluminum oxide, magnesium oxide, calcium carbonate, kaolin,
Inorganic fine particles such as talc, titanium oxide, barium sulfate and the like, and organic fine particles made of a heat-resistant polymer such as a cross-linked silicone resin, a cross-linked polystyrene resin, a cross-linked acrylic resin, a urea resin, a melamine resin and the like can be contained. Of these, silicon oxide is preferred.

In addition, other resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and olefinic ionomer, stabilizers, antioxidants, ultraviolet absorbers, fluorescent brighteners, etc. are contained as necessary. Can also.

The polyester film in the present invention comprises:
It is preferable that the film has high transparency, and it is particularly preferable that the film is a highly transparent biaxially stretched film.

The polyester film in the present invention comprises:
It can be manufactured by a conventionally known method. For example, a biaxially stretched polyester film is produced by drying a polyester, melting it with an extruder, extruding it from a die (eg, T-die, I-die, etc.) onto a rotary cooling drum, and quenching to produce an unstretched film. Then, the unstretched film can be produced by stretching in the machine direction and the transverse direction and, if necessary, by heat setting. The thickness of the polyester film is preferably from 5 to 250 μm.

In the present invention, a layer containing a component having an antistatic property and a component having an antifouling property is provided on one side of a plastic film, and a fine adhesive layer is provided on the opposite side.

The components having antistatic properties (antistatic agents) include compounds having any antistatic properties such as surfactants and conductive resins.

Examples of the antistatic agent include various cationic antistatic agents having a cationic group such as a quaternary ammonium salt, a pyridinium salt, a tertiary amino group, a sulfonate group, and a sulfate ester group. , Phosphate bases, anionic antistatics having anionic groups such as phosphonates, amino acid-based, aminosulfate-based amphoteric antistatics, amino alcohol-based, glycerin-based, polyethylene glycol-based nonionics And various types of surfactant-type antistatic agents such as antistatic agents, and high-molecular-weight antistatic agents obtained by increasing the molecular weight of the above-described antistatic agents. Also, tertiary amino groups and quaternary Monomers and oligomers having an ammonium group and polymerizable by ionizing radiation, for example, N, N-dialkylaminoalkyl (meth) acrylate Nomar also polymerizable antistatic agents such as those quaternary compounds can be used.

Further, conductive polymers such as polyaniline, polypyrrole, and polythiophene, and tin, antimony-based fillers and indium oxide-based fillers dispersed in a binder can also be used. Of these, quaternary ammonium salt type cationic compounds are preferred.

As the component having antifouling properties (antifouling agent), a polymer having a long alkyl side chain is preferable.
A copolymer of acrylic acid and an alkyl acrylate having an alkyl chain having 12 or more carbon atoms, particularly 16 to 20 carbon atoms, is more preferred. When the number of carbon atoms in the alkyl chain of the alkyl acrylate is less than 12, sufficient releasability may not be obtained.

Of these, particularly preferred are copolymers obtained by long-chain alkylation of polyvinyl alcohol or polyethyleneimine with chlorinated alkylol or alkyl isocyanate. Specifically, a copolymer obtained by reacting polyvinyl alcohol with octadecyl isocyanate is preferred. Polyvinyl-N-octadecyl carbamate,
Examples include polyethyleneimine-N-octadecylcarbamate obtained by reacting polyethyleneimine with octadecyl isocyanate.

In the present invention, a silicone-based or fluorine-based release agent can be used as a stain preventive.

In the present invention, the weight ratio (solid content weight ratio) of the antistatic agent to the antifouling agent is preferably in the range of 5/95 to 95/5.

In the present invention, a component having an antistatic property and a component having an antifouling property are included in order to improve the strength of the layer, adhesion to the polyester film, water resistance, solvent resistance, blocking property, and the like. Preferably, the layer contains a binder.

The binder may be a thermoplastic resin such as a thermoplastic polyester resin, an acrylic resin or a polyvinyl resin and / or a polymer such as a thermosetting resin such as a thermosetting acrylic resin, a urethane resin, a melamine resin, or an epoxy resin. It is preferable to include a compound, and further, as a crosslinking agent, at least one selected from methylolated or alkylolated melamine-based, urea-based, glyoxal-based, acrylamide-based compounds, epoxy compounds, and polyisocyanates. Is particularly preferred.

The ratio of the amounts of the antistatic agent, the antifouling agent, and the optional binder to be formed in the above-mentioned layer varies depending on the application, but the ratio must satisfy the following layer characteristics. Surface resistivity: 10 ⁷ to 10 ¹³ Ω / □, preferably 1
0 ⁷ ~10 ¹⁰ Ω / □ peel force: 20~400g / 25mm, preferably 30
１５０150 g / 25 mm The peeling force represents the force when a pressure-sensitive adhesive tape (manufactured by Nitto Denko Corporation, product number: 31B) is attached to the measurement surface and peeled off at an angle of 180 ° at a speed of 300 mm / min.

In the present invention, the thickness of the above-mentioned layer is set to 0.1.
It is preferably from 01 to 1 μm, more preferably from 0.02 to 0.3 μm. If the thickness is less than 0.01 μm, a sufficient antistatic effect and antifouling effect may not be obtained. On the other hand, a layer exceeding 1 μm is excessively expensive and uneconomical.

The above-mentioned layer in the present invention is preferably formed by applying an organic solvent as a medium, but can also be formed by applying as an aqueous coating solution (using water as a medium). Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene,
Xylene, methanol, ethanol, n-propanol, isopropanol and the like can be exemplified. These can be used alone or in combination of two or more.

The solid content of the coating solution in the present invention is not particularly limited, but is preferably 30% by weight or less, more preferably 0.5 to 30% by weight. If this concentration exceeds 30% by weight, the appearance of the coated film may be deteriorated.

In the present invention, the above-mentioned layer is preferably formed by applying a coating solution to one surface of a plastic film. For example, in the case of a polyester film, the film is stretched by the above-described method to form a crystal. A polyester film in which the orientation is completed or a polyester film in which the crystal orientation has not been completed are preferably mentioned.

Examples of the polyester film in which the crystal orientation is completed include an unstretched film obtained by heat-melting a polyester, biaxially stretching in a machine direction and a transverse direction, and heat setting. As a polyester film before the crystal orientation is completed, an unstretched film in which the polyester is hot-melted and directly formed into a film, a uniaxially stretched film in which the unstretched film is oriented in either the longitudinal direction or the transverse direction, An example is a film stretched and oriented at a low magnification in two directions, that is, a longitudinal direction and a lateral direction (a biaxially stretched film before being finally stretched again in a longitudinal direction and a lateral direction to complete oriented crystallization).

As a method of applying the coating liquid to the plastic film, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a microgravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination. When an aqueous coating liquid is used, a small amount of an organic solvent may be contained for the purpose of assisting the stability of the coating liquid.

The surface protective film of the present invention is provided with a slightly adhesive layer on the surface opposite to the surface on which the stain prevention layer is provided. A release (release) film treated with a release agent can be attached to the surface of the slightly adhesive layer, if necessary.

As the pressure-sensitive adhesive constituting the fine pressure-sensitive adhesive layer, an acrylic, rubber-based or urethane-based pressure-sensitive adhesive can be used. In particular, an acrylic pressure-sensitive adhesive is preferable from the viewpoint of the durability of the fine pressure-sensitive adhesive layer.

The adhesive layer needs to be free from migration of the adhesive on the other side when the adhesive film is peeled off after the release film is bonded thereto. Is preferably 3 to 50 g / 25 mm.

Examples of the type of the pressure-sensitive adhesive include a thermosetting type, a UV-curing type, an EB-curing type, and a hot-melt type. Can be used as appropriate.

The peeling force of the slightly adhesive layer is determined by applying the force when a slightly adhesive surface is stuck to a stainless steel plate (SUS304) and peeled at a speed of 300 mm / min and an angle of 180 ° after one day at 23 ° C. Express.

The application method such as the application method and application conditions of the slightly adhesive layer is carried out by a die coating method, a doctor blade coating method or the like, in addition to the above-mentioned coating method of the layer containing the antistatic agent and the antifouling agent. be able to.

In the present invention, the thickness of the slightly adhesive layer is 3 to
It is preferably 100 μm, more preferably 5 to 50 μm.
If the thickness is less than 3 μm, a sufficient fine adhesive effect may not be obtained, while a layer exceeding 100 μm is excessively expensive and uneconomical.

[0041]

The present invention will be further described below with reference to examples. In addition, each characteristic value was measured by the following method.

(1) Surface Specific Resistance Using a specific resistance measuring device manufactured by Takeda Riken Co., Ltd.
℃, measurement humidity 65% RH, applied voltage 100V
The surface resistivity after 1 minute was measured. The surface specific resistance is preferably less than 1 × 10 ¹³ Ω / □.

(2) Antifouling property A surface protective film is laminated on a polarizing plate with an adhesive, cut into dimensions for a 16-inch display, laminated and then inspected for foreign matter on the polarizing plate, and the adhesive sticking out of the cut surface is inspected. The ratio of the number counted as foreign substances due to the agent to the total number of foreign substances was calculated and evaluated based on the following criteria. ：: less than 1% △: 1% or more and less than 20% ×: 20% or more

[Example 1] As an antistatic layer, a quaternary ammonium salt type cationic polymer compound (manufactured by Soken Chemical Co., Ltd., Elecond PQ-50B), polyethyleneimine octadecyl carbamate (manufactured by Nippon Shokubai Co., Ltd., R
P-20), a polyester resin (Espel 1510, manufactured by Hitachi Chemical Co., Ltd.) and a melamine resin (Nikarac NS-11, manufactured by Sanwa Chemical Co., Ltd.) in 20/2
The mixture was mixed at a ratio of 0/40/20 (weight ratio of solid content), and diluted with a mixed solvent mainly composed of a ketone solvent and an aromatic solvent to a solid content concentration of 1% by weight to prepare a coating liquid. This coating solution is applied to one surface of a highly transparent biaxially stretched polyester film (Tetron film, Tetron film, G2-38 μm),
Apply 5 g / m ² using a gravure coater,
The coating was dried and cured at a temperature of 2 ° C. for 2 minutes to form a layer containing an antistatic agent and an antifouling agent.

Next, an acrylic pressure-sensitive adhesive (SG-80, manufactured by Teikoku Chemical Co., Ltd.) was formed on the surface opposite to this layer as a fine pressure-sensitive adhesive layer.
0) 100 parts (parts by weight of solid content) isocyanate curing agent (Coronate H, manufactured by Nippon Polyurethane Co., Ltd.)
L) A coating liquid to which 10 parts (parts by weight of solid content) was added was applied using a gravure coater, and the coating was dried and cured at 100 ° C. for 2 minutes to provide a 20 μm-thick slightly adhesive layer, thereby protecting the surface. A film was made. Table 1 shows the characteristics of the surface protective film.

Then, the surface protective film was bonded to a polarizing plate, the laminate was further bonded to a TFT liquid crystal cell, and then the surface protective film was peeled off. Was also not recognized.

Example 2 Example 1 was repeated, except that a modified aliphatic dimethylethylammonium ethosulfate (Nippon Yushi Co., Ltd., Elegan 264-WAX) was used instead of the quaternary ammonium salt type cationic polymer compound. A surface protection film was prepared in the same manner as described above. Table 1 shows the characteristics of the surface protective film. When peeling charging and TFT element destruction were evaluated in the same manner as in Example 1, peeling charging hardly occurred, and no destruction of the TFT element was observed.

Example 3 A surface protection film was prepared in the same manner as in Example 1 except that polyvinyl-N-octadecyl isocyanate (Aciol RA-585S, manufactured by Asio Sangyo Co., Ltd.) was used instead of polyethyleneimine octadecyl carbamate. did. Table 1 shows the characteristics of the surface protective film. When peeling charging and TFT element destruction were evaluated in the same manner as in Example 1, peeling charging hardly occurred, and no destruction of the TFT element was observed.

Comparative Example 1 A surface protective film was prepared in the same manner as in Example 1 except that a layer containing an antistatic agent and an antifouling agent was not provided. Table 1 shows the characteristics of this surface protective film.
Shown in Then, peeling charging and TF were performed in the same manner as in Example 1.
When the destruction of the T element was evaluated, about 50% of the TFT element was destroyed by the peeling and charging of the surface protective film.

Comparative Example 2 A surface protective film was prepared in the same manner as in Example 1 except that the quaternary ammonium salt type cationic polymer compound was not used. Table 1 shows the characteristics of the surface protective film. When the peeling charge and the destruction of the TFT element were evaluated in the same manner as in Example 1, about 50% of the TFT element was destroyed by the peeling charge of the surface protective film.

Comparative Example 3 A surface protective film was prepared in the same manner as in Example 1 except that polyethyleneimine octadecyl carbamate was not used. Table 1 shows the characteristics of the surface protective film. When peeling charging and TFT element destruction were evaluated in the same manner as in Example 1, neither peeling charging nor TFT element destruction were observed. However, in the subsequent foreign substance inspection, a large number of defective judgment points were attributed to the surface protective film. , The product yield was reduced.

[0052]

[Table 1]

[0053]

The surface protective film of the present invention has little peeling charge when peeled off, and particularly when the protective film is bonded to a polarizing plate and cut, the adhesive sticking out of the cut surface adheres to the surface of the protective film. This is useful as a surface protective film that can prevent the occurrence of defects and can accurately inspect the product for defects.

Claims (8)

[Claims] 1. A surface protective film comprising: a layer containing an antistatic component and a component having an antifouling property provided on one side of a plastic film, and a fine adhesive layer provided on the other side. 2. The surface protective film according to claim 1, wherein the component having antifouling property is a copolymer obtained by long-chain alkylating polyvinyl alcohol or polyethyleneimine with chlorinated alkylol or alkyl isocyanate. 3. The surface protective film according to claim 1, wherein the component having an antistatic property is a quaternary ammonium salt type cationic compound. 4. A layer containing a component having an antistatic property and a component having an antifouling property, wherein the layer comprising a melamine resin or a polyester resin is at least one selected from melamine compounds, epoxy compounds and isocyanate compounds.
The surface protective film according to claim 1, comprising a polymer crosslinked with a seed. 5. The surface protective film according to claim 1, wherein the plastic film is a polyester film. 6. The surface protective film according to claim 5, wherein the polyester film is a polyethylene terephthalate film or a polyethylene-2,6-naphthalate film. 7. The peeling force of the slightly adhesive layer is 3 to 50 g / 25 m.
The surface protective film according to any one of claims 1 to 6, which is m. 8. The surface protective film according to claim 1, which is used for protecting the surface of at least one laminate selected from a polarizing plate, a retardation plate, and a viewing angle widening film.