JP2001219520A - Film roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film roll wherein a surface protective film having a self-adhesive layer can be wound into a roll form without laminating release paper to the self-adhesive layer, and the surface protective layer can be easily peeled if necessary even if the surface of the self-adhesive layer of the surface protective film unwound from the roll is bonded to a partner base material. SOLUTION: This film roll is obtained by taking up the surface protective film. The self-adhesive layer (B) is provided on the single surface of a biaxially oriented polyester film (A), and a protective layer (C) is provided on the opposite surface thereof. The self-adhesive layer (B) is brought into contact with the protective layer (C), and satisfies all of conditions of (1) no foreign matter with a size of 25 μm or more is present on the biaxially oriented polyester film (A) per an area (310.8 cm2), (2) at most 10 foreign matters with a size of below 25 μm are present on the biaxial oriented polyester film (A) per an area (310.8 cm2), (3) the protective layer (C) contains a release agent and an antistatic agent, (4) the peel strength of the protective layer (C) and the self-adhesive layer (B) and the nomal state selfadhesive strength of the self-adhesive layer (B) are within a proper range, and (5) the thickness of the self-adhesive layer (B) is within a proper range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film roll having a surface protective film wound thereon, and more particularly to a film roll which can be wound into a roll without bonding a release paper to an adhesive layer of the surface protective film. Even if the pressure-sensitive adhesive layer surface of the surface protective film unwound from is bonded to the counterpart substrate, it can be peeled lightly if necessary, and even after aging, the peeling force does not increase, and it is highly transparent. ,
The present invention relates to a film roll wound with a surface protective film that does not impair the inspectability of a bonded base material.

[0002]

2. Description of the Related Art In general, a surface protective film has a structure in which a plastic film is used as a base material and an adhesive layer is provided on one side of the film. In recent years, its use for protecting the surface of optical components has been increasing. For example, it is used for surface protection during the production of various displays such as televisions, computers, word processors and car navigation systems. It is used for protecting the surface of optical components and optical laminates such as retardation films and viewing angle widening films. In general, a transparent olefin-based film such as polyethylene or polypropylene is used as a base material of the surface protection film, and the surface protection film is used after the production and assembly of a liquid crystal display or the like is completed or in actual use. The film is removed by peeling.

[0003] In recent years, liquid crystal displays of the TFT (thin film transistor) type have attracted particular attention due to their high definition and high responsiveness, and the demand for surface protective films during their production has become strict. For example, when manufacturing a polarizing plate or a liquid crystal display, etc., the product is often inspected for defects while the surface protective film is attached. As in the conventional case, the base material is transparent for an olefin-based film such as a polyethylene film. Inferior properties and a large amount of gels such as fish eyes cause foreign matter defects in the defect inspection, and it has become difficult to inspect the product itself with high accuracy. In addition, the surface protection film,
Once affixed to a polarizing plate, a liquid crystal display, or the like, it often remains attached for a long time until the next manufacturing process. Then, after the completion of the inspection and the like, when the peeling becomes heavy when the film is peeled, the workability deteriorates, or a part of the adhesive of the film remains, and a defect such as a foreign substance or distortion occurs in a display inspection or the like of a display. There was a problem.

On the other hand, on the pressure-sensitive adhesive layer surface of the surface protective film before use, release paper is generally used in a manufacturing process for forming the pressure-sensitive adhesive layer, and is wound up as it is to be a product. However, when the surface protective film is used, the release paper is simply peeled off and discarded, which is a problem in terms of generation of waste and cost.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and it is possible to wind a roll without bonding a release paper to an adhesive layer of a surface protective film. Even if the pressure-sensitive adhesive layer surface of the surface protective film unwound from is bonded to the counterpart substrate, it can be peeled lightly if necessary, and even after aging, the peeling force does not increase, and it is highly transparent. It is another object of the present invention to provide a film roll wound with a surface protective film which does not impair the inspection property of the mating base material.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has used an adhesive having a specific physical property as an adhesive layer and a surface protection layer formed on the opposite surface. Provide a release layer suitable for this adhesive layer on the layer surface,
Further, they have found that an improved film roll of a surface protective film can be obtained by combining with a biaxially oriented polyester film having an additional performance, and have reached the present invention.

That is, according to the present invention, a biaxially oriented polyester film (A) is provided with a pressure-sensitive adhesive layer (B) on one surface and a protective layer (C) on the other surface, and is provided with a pressure-sensitive adhesive layer (B). A film roll obtained by bringing B) into contact with the protective layer (C) and winding the film, wherein the following (1) to (6)
A film roll satisfying all of the above conditions. (1) The biaxially oriented polyester film (A) has no foreign matter having a size of 25 μm or more per area (area: 310.8 cm ² ) having a side length of 210 mm and a side length of 148 mm perpendicular thereto. (2) In the biaxially oriented polyester film (A), a size of 5 μm or more per 210 mm in side length and 148 mm in side length (area of 310.8 cm ² ) perpendicular to it, 2
There are only at most 10 foreign particles of less than 5 μm. (3) The protective layer (C) contains a release agent and an antistatic agent. (4) The peeling force when peeling the protective layer (C) from the pressure-sensitive adhesive layer (B) is 10 mN / 25 mm or more and 1000 mN / 25 m.
m or less. (5) The adhesive strength of the pressure-sensitive adhesive layer (B) to the stainless steel plate is 30 mN / 25 mm or more and 500 mN / 25 mm or less.
5 times or more and 2 times or less. (6) The thickness of the pressure-sensitive adhesive layer (B) is 3 μm or more and 50 μm or less.

Further, the visible light transmittance of the surface protective film constituting the film roll is 70% or more,
Further, the haze is preferably 10% or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The surface protective film in the present invention has a configuration in which a pressure-sensitive adhesive layer is provided on one surface of a biaxially oriented polyester film serving as a substrate, and a protective layer is provided on the other surface.

[Polyester Film] A biaxially oriented polyester film having high transparency, high productivity and excellent workability is used as a substrate of the surface protective film in the present invention. The biaxially oriented polyester film is not particularly limited, but is preferably a biaxially oriented polyethylene terephthalate film or a biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film. Further, in the configuration, a multilayer structure having an arbitrary number of layers by co-extrusion may be adopted.

The polyester constituting such a biaxially oriented polyester film is preferably a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component, such as polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate. And polyethylene-2,6-naphthalenedicarboxylate. Further, a copolymer in which a part of these is substituted by another component, or a mixture with polyalkylene glycol or another resin may be used.

The above biaxially oriented polyester film is
It can be manufactured by a conventionally known method such as a sequential biaxial stretching method and a simultaneous biaxial stretching method. For example, the sequential biaxial stretching method can be performed by the following method. After sufficiently drying the polyester polymer, by melt extrusion method,
Extruded from a die (e.g., T-die, I-die, etc.) onto a cooling drum and quenched to produce an unstretched film or a co-extruded unstretched film.
Stretched in the longitudinal direction at a temperature of ~ 140 ° C in the range of 2 to 5 times,
Then, the film is stretched in the horizontal direction at a temperature of 80 to 150 ° C in a range of 2 to 5 times, and further at a temperature of 160 to 260 ° C.
It can be manufactured by heat setting for 100 seconds. The heat setting may be performed under limited shrinkage. In addition, it is preferable to use an electrostatic adhesion method during melt extrusion.

Further, the isotropy of the biaxially oriented polyester film should be as good as possible in order not to cause breakage in a specific direction. For example, the stretching ratio in the longitudinal direction and the transverse direction should be the same. Is preferred.

The thickness of the film is not particularly limited.
500 μm is preferred. More preferably, in order to improve workability such as bonding and productivity, 10 to 200 μm
m is preferred.

Such a biaxially oriented polyester film is provided with a lubricant such as calcium carbonate, alumina, kaolin, etc. in order to improve the slipperiness when winding the film and the handling during processing such as application of an adhesive. And inorganic fine particles such as silica, titanium oxide, barium sulfate, and zeolite, and organic fine particles such as silicone resin, cross-linked polystyrene, and acrylic resin, and other additives such as a stabilizer and an ultraviolet absorber. ,Flame retardants,
An antistatic agent or the like can be contained. The addition time of the fine particles and additives is not particularly limited as long as it is a stage until the biaxially oriented polyester film is formed.For example, it may be added at the polymerization stage, or may be added at the time of film formation. Good.

In the biaxially oriented polyester film, the center line average roughness (Ra) is preferably from 2 nm to 500 nm. If the center line average roughness is less than 2 nm, there is a risk of impairing transportability such as difficulty in processing, and if the center line average roughness is more than 500 nm, the transparency deteriorates and the testability deteriorates. When the pressure-sensitive adhesive layer is provided, particularly when the pressure-sensitive adhesive layer is applied to the protective layer surface and the opposite surface is provided by a transfer method, there is a concern that the biaxially oriented polyester film may not be uniformly adhered due to unevenness.

Further, in the biaxially oriented polyester film, a foreign substance having a size of 25 μm or more is contained in a film (area: 310.8 cm ² ) having a side length of 210 mm and a side length of 148 mm orthogonal thereto. Is preferably not present and the number of foreign matters having a size of 5 μm or more and less than 25 μm is 10 or less. When a foreign substance having a size of 25 μm or more is present, voids or the like are generated during application or transfer of the adhesive,
Since the pressure-sensitive adhesive comes off or rises only in that portion beyond the size, there may be a local appearance defect that can be visually confirmed. Further, when there are more than 10 foreign substances having a size of 5 μm or more and less than 25 μm, although the size is hard to be visually confirmed, a defect may be noticeable due to the large size.

[Pressure-sensitive adhesive layer] The pressure-sensitive adhesive layer laminated on one side of the biaxially oriented polyester film takes into account not only indoors but also outdoors, and withstands various light rays at the time of inspection. It is necessary to
In order to prevent migration of components from the pressure-sensitive adhesive layer to the mating substrate bonded, a layer made of an acrylic pressure-sensitive adhesive is particularly preferable.

The thickness of the pressure-sensitive adhesive layer of the surface protective film is preferably from 3 μm to 50 μm. 3 μm thick
If it is less than 3, when bonded to a polarizing plate or the like having irregularities, the hardness of the biaxially oriented polyester film, which is the base material of the surface protective film, is dominant, and the pressure-sensitive adhesive does not sufficiently spread on the polarizing plate surface. In addition, a necessary adhesive strength cannot be obtained, and a partial lifting may occur when bonding. 50μ thickness
If it is larger than m, the adhesive strength becomes unnecessarily high, and when applying an adhesive, there is a problem in terms of thickness control, curing control, and cost.

In the film roll of the present invention, a surface protective film having a pressure-sensitive adhesive layer on one side of a substrate and a protective layer on the other side is wound by bringing the pressure-sensitive adhesive layer and the protective layer into contact (lamination). Configuration. The surface protective film is unwound from the film roll and is attached to a mating component (a polarizing plate, a stainless steel plate, or the like) and is used for protecting the mating component surface. Then, when the mating component is subjected to the processing step or the intended use, the bonded surface protection film is peeled off.

That is, it is necessary that the pressure-sensitive adhesive layer of the surface protective film has such characteristics that it can be easily bonded to a counterpart surface to be bonded (protective layer, polarizing plate, stainless steel plate, etc.) and can be easily peeled off. In order for the pressure-sensitive adhesive layer to exhibit such characteristics, it is preferable to satisfy the following range. (1) Peeling force when peeling the protective layer (C) from the pressure-sensitive adhesive layer (B) is 10 mN / 25 mm or more and 1000 mN / 25 m.
m or less. (2) Normal adhesion to stainless steel plate: 30 mN / 25
mm or more and 500 mN / 25 mm or less, and 60 ° C
The rate of change in adhesive strength after one week is 0.5 times or more and 2 times or less.

The peeling force against the protective layer is 10 mN / 25 m
If it is less than m, winding deviation may occur at the time of roll, and if the peeling force is greater than 1000 mN / 25 mm, a large amount of tension is required for a film having a wide width at the time of unwinding from the roll. Becoming
In addition, the peeling charge increases, which may cause damage to the film surface. On the other hand, if the normal adhesive strength to the stainless steel plate is less than 30 mN / 25 mm, it is not preferable because end-turning may occur or the adhesive may be easily peeled off by any contact. Also, 500mN / 2
If the thickness exceeds 5 mm, for example, in a step of peeling the surface protective film from the polarizing plate or the like, the polarizing plate is not easily peeled off, so an inadvertent force is applied to the polarizing plate, which is not preferable because it may be deformed.

Furthermore, it is necessary that the normal adhesion to the stainless steel plate does not change over time,
It is preferable that the change rate of the normal adhesive strength after one week is 0.5 times or more and 2 times or less. If it is less than 0.5 times and more than 2 times, the fluctuation of the adhesive force becomes large, and setting and management become complicated when the surface protective layer is automatically peeled off. Become.

The center line average roughness (Ra) of the pressure-sensitive adhesive layer
Is preferably 2 nm or more and 500 nm or less. There is no particular problem in the case where the center line average roughness is small.
When the thickness is larger than 00 nm, when the film is bonded to a polarizing plate or the like, the pressure-sensitive adhesive layer does not adhere completely even when the thickness, the adhesive force, and the peeling force satisfy the above range, and distortion or dents are generated. Bubbles and the like may be generated in some parts.

The pressure-sensitive adhesive to be used is not particularly limited, but in order to satisfy the above characteristics, for example, an acrylic pressure-sensitive adhesive described below is preferable. The acrylic pressure-sensitive adhesive includes a solvent-based pressure-sensitive adhesive and an emulsion-based pressure-sensitive adhesive, but a solvent-based pressure-sensitive adhesive is particularly preferable for easily obtaining the above-mentioned pressure-sensitive adhesive properties. As the acrylic solvent-based pressure-sensitive adhesive, one obtained by solution polymerization is used to satisfy various properties. As a raw material, a known material for solution polymerization of an acrylic pressure-sensitive adhesive can be used. For example,
As the main monomer as the skeleton, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylates such as octyl acrylate,
As comonomers for improving cohesion, vinyl acetate, acrylonitrile, styrene, methyl methacrylate, etc., further promote high cross-linking, and as a functional group-containing monomer to impart a stable low adhesive strength, methacrylic acid, acrylic acid, Itaconic acid, hydroxyethyl methacrylate, glycidyl methacrylate, and the like.Examples include low tackiness and tackiness, and high cohesion.To achieve high crosslinking with an isocyanate-based curing agent, an aziridine-based curing agent, and the like, Particularly, those containing many hydroxyl groups are preferable. In order to soften the pressure-sensitive adhesive layer to some extent because air bubbles and the like are not generated when bonded to a mating base material having irregularities, among the above components, a main monomer as a skeleton having a low glass transition temperature (Tg) is used. It is preferable to use a large number of components, and on the other hand, to use a small amount of a comonomer component having a high Tg and improving cohesion.

The synthesis of the pressure-sensitive adhesive can be carried out by a known method. For example, in the presence of an organic solvent such as ethyl acetate or toluene, the necessary raw materials are charged into a reaction tank, and heated using a peroxide system such as benzoyl peroxide or an azobis system such as azobisisobutyronitrile as a catalyst. It can be polymerized below. To increase the molecular weight, for example,
Ethyl acetate is preferably used in the method of batch-injecting monomers at the beginning and in the kind of organic solvent used, because toluene has a large chain transfer coefficient and suppresses polymer growth. At this time, the weight average molecular weight (Mw) is preferably 300,000 or more, more preferably 400,000 or more. If the molecular weight is less than 300,000, even if cross-linked with an isocyanate curing agent, sufficient cohesive strength cannot be obtained, and even when the holding force under load is evaluated, the material falls immediately. When the adhesive is peeled off after a lapse of time after bonding, the adhesive may remain on a stainless plate, a polarizing plate, or the like. In order to increase the molecular weight, control at the polymerization stage is important, but in general, the solvent system does not increase the molecular weight even if sufficient adhesive strength is obtained. It is necessary to improve the rate.

The curing agent for the pressure-sensitive adhesive is not specified, but in particular, acrylic solvent-based general isocyanate-based, epoxy-based, and aziridine-based curing agents can be used. The adhesive may contain additives such as a stabilizer, an ultraviolet absorber, a flame retardant, and an antistatic agent. Further, the additive is necessary to suppress the increase in the adhesive force by using an adhesive having a low glass transition temperature, and also to suppress the increase in the adhesive force over time. Organic resin such as wax, silicone oil,
Although a fluorine-based resin or the like can be used, it is preferable that those components migrate to the mating base material and do not impair the testability. For this reason, it is good that the adhesive component is partially reacted with, for example, in an organic resin such as a wax, a higher fatty acid ester having a reactive functional group such as a hydroxyl group, a carboxyl group, an epoxy group, an amine group, and an isocyanate group is used. Preferably, it is used.

The application of the pressure-sensitive adhesive solution to the biaxially oriented polyester film can be performed at any stage. Also,
When applying the coating solution to the biaxially oriented polyester film, if necessary, as a preliminary treatment to improve the adhesion, coating properties, flame treatment, corona discharge treatment, the biaxially oriented polyester film surface, By applying a physical surface treatment such as a plasma discharge treatment, or by applying a chemical surface treatment to apply an organic resin-based or inorganic resin-based paint during or after film formation, the adhesive and the biaxial The adhesion of the oriented polyester film can be strengthened.

As a method for applying the pressure-sensitive adhesive, any known method can be used, and for example, a die coater method, a gravure roll coater method, a blade coater method, a spray coater method, an air knife coat method, a dip coat method and the like are preferable. And can be used alone or in combination.

The order of forming the pressure-sensitive adhesive layer and the protective layer is not particularly limited. However, the film roll of the present invention is characterized in that it is wound without using a release paper, so that the protective layer is protected first. It is preferable to provide a layer and provide an adhesive layer on the opposite surface. In addition, an adhesive layer can be provided on the protective layer surface provided earlier, and after winding a film having this layer structure to form a film roll, and unwinding the surface protective film, the adhesive layer is provided on both surfaces of the base film. A surface protective film having a layer and a protective layer formed thereon can be obtained. In the above forming order, in order to peel the pressure-sensitive adhesive layer more lightly from the protective layer surface, it is better to apply directly on the opposite surface of the protective layer, and the surface of the pressure-sensitive adhesive layer is partially crosslinked and cured by drying before being wound up. This is preferred because the adhesive strength is reduced.

The drying temperature at the time of applying the pressure-sensitive adhesive is preferably such that the residual solvent is as small as possible. For this purpose, the drying temperature and time are not specified, but preferably 50 to 50.
It is preferable to provide a drying time of 10 seconds to 5 minutes at a temperature of 150 ° C.

Since the pressure-sensitive adhesive has fluidity, and when an isocyanate-based curing agent or the like is used as a cross-linking agent, the reaction is not yet completed immediately after heating and drying, and the reaction is completed. Curing is necessary to obtain Generally, when heated at room temperature for about one week or more, for example, at about 50 ° C., three days or more are preferable. In the case of heating, if the temperature is too high, the flatness of the plastic film may be deteriorated.

[Protective Layer] In the surface protective film of the present invention, a protective layer is provided on the surface of the biaxially oriented polyester film opposite to the pressure-sensitive adhesive layer. The protective layer preferably contains a release agent so that it can be easily separated from the pressure-sensitive adhesive layer. In addition, the protective layer is provided to prevent the mating member (such as a TFT display plate) from being destroyed by peeling charge generated when the pressure-sensitive adhesive layer is stripped from the mating member, or to prevent dust on the surface of the surface protective film. It is preferable to contain an antistatic agent in order to prevent adsorption and easily remove attached dust. The release agent and the antistatic agent may be mixed and provided as one layer, or an antistatic layer containing the antistatic agent may be provided first, and a release layer containing the release agent may be provided thereon. . In this case, since the outermost layer needs to have releasability from the pressure-sensitive adhesive layer, it is necessary to provide the release layer so as to be the outermost layer. Further, the antistatic agent may be mixed in the pressure-sensitive adhesive layer, or may be provided between the pressure-sensitive adhesive layer and the biaxially oriented polyester film.

A releasing agent or an antistatic agent is contained in a binder to improve the strength of the layer, the adhesion to the biaxially oriented polyester film, the water resistance, the solvent resistance, the blocking property and the like. Preferably, a layer is formed. As the binder, thermoplastic polyester resin, thermoplastic resin such as acrylic resin and / or thermosetting acrylic resin,
Polymer compounds such as thermosetting resins such as urethane resins, melamine resins, and epoxy resins are exemplified. As the crosslinking agent used together with the above resin, it is particularly preferable to include at least one selected from methylolated or alkylolated melamine-based, urea-based, acrylamide-based compounds, epoxy compounds, and polyisocyanates. In the case where the antistatic layer and the release layer are separately provided, it is preferable that the binder component used for both is a similar main component because the adhesion between them is improved.

The antistatic agent is not particularly restricted but includes, for example, quaternary ammonium salts, pyridinium salts,
Various cationic antistatic agents having a cationic property such as a primary to primary amino group, a sulfonate group, a nitrate ester group,
Various types of anionic antistatic agents such as phosphate bases, etc., amphoteric antistatic agents such as amino acids and aminosulfates, and nonionic antistatic agents such as amino alcohols, glycerin and polyethylene glycol Surfactant-type antistatic agents, and the above polymerized ones, etc. can be used. Further, those in which conductive polymers such as polyaniline, polypyrrole, and polythiophene and oxide-based fillers such as tin and antimony are dispersed can also be used. Further, a metal layer of silver, tin, or the like may be provided by a vapor phase growth method, a vacuum evaporation method, a sputtering method, a plasma CVD method, or the like.

The release layer is used not only to prevent contamination of the surface protective film surface and to improve dirt wiping properties, but also to form a surface on which the pressure-sensitive adhesive layer is to be applied, and when the film is wound into a roll, release paper is used. Therefore, it is preferable to have an appropriate peeling force and to have durability. Examples of the release agent include silicone-based, fluorine-based, and alkyl polymer-based release agents. Among them, an alkyl polymer-based material having a particularly low migration property is preferable in order to prevent contamination in the process. In particular, a polymer having a long alkyl side chain is preferable, and a copolymer of an alkyl acrylate having an alkyl group having 12 or more carbon atoms, particularly 16 to 20 carbon atoms, and acrylic acid is preferable. The alkyl chain of the alkyl acrylate has 1 carbon atom
If it is less than 2, sufficient releasability may not be obtained. Among them, particularly preferred are copolymers obtained by long-chain alkylation of polyvinyl alcohol or polyethyleneamine with chlorinated alkylol or alkyl isocyanate.

When the biaxially oriented polyester film is provided with the protective layer, it can be applied before the completion of the crystal orientation at the time of film formation or after the film formation at the completion of the crystal orientation.

As a method for coating the biaxially oriented polyester film, any known method can be applied. For example,
A roll coating method, a gravure coating method, a reverse coating method, a spray coating method and the like can be used alone or in combination. The coating of the protective layer can be carried out by applying a coating liquid containing the components for forming each to a base film, and drying by heating to form a coating film. The heating conditions are 80-160 ° C. for 10-120 seconds, especially 120-160 ° C.
Preferably at 150 ° C. for 20 to 60 seconds.

When applying the coating solution to the biaxially oriented polyester film, if necessary, as a pretreatment for improving the adhesion and coating properties, the same as in the case of applying the pressure-sensitive adhesive layer. Chemical treatment of applying a physical surface treatment such as flame treatment, corona discharge treatment, plasma discharge treatment, etc. to the biaxially oriented polyester film surface, or applying an organic resin or inorganic resin paint during or after film formation. By performing the target surface treatment, the adhesiveness between the pressure-sensitive adhesive and the biaxially oriented polyester film can be strengthened.

The surface protective film of the present invention is required to have high transparency for easy inspection. In particular,
Visible light transmittance is 70% or more, and haze is 10
% Is preferable. If the light transmittance is less than 70% and the haze is more than 10%, the transparency is poor, so that foreign matter cannot be detected, for example, in a defect inspection such as a foreign matter when a surface protective film is bonded to a polarizing plate. It is concerned.

[0041]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, each physical property value in an Example and a comparative example was measured as follows.

(1) Peeling Force The surface of the pressure-sensitive adhesive layer of the surface protective film is directly adhered to the surface of the protective layer of the same surface protective film by a rubber roller. It is left as it is under the condition of a temperature of 23 ° C. and a humidity of 55 ± 5% RH for 30 minutes, and then cut into strips having a width of 25 mm. Using a tensile tester (Strograph manufactured by Toyo Seiki Co., Ltd.), the bonded film on the protective surface side is pulled at 180 ° at 300 mm / min, and the strength is defined as the peeling force.

(2) Normal adhesive strength The adhesive layer surface of the surface protection film is directly adhered to the washed stainless steel plate with a rubber roller.
Reciprocate one time with a kg rubber roller to make close contact. It is left as it is under the condition of a temperature of 23 ° C. and a humidity of 55 ± 5% RH for one day, and then cut into strips having a width of 25 mm. This was attached to a tensile tester (Strograph manufactured by Toyo Seiki Co., Ltd.), and a stainless steel plate was fixed.
Per minute at 180 °, and the strength is defined as the normal adhesive strength.

(3) Adhesive force after 1 week at 60 ° C. A sample prepared in the same manner as the above normal adhesive force was allowed to stand at 60 ° C. for 1 week, returned to room temperature, and allowed to stand for 30 minutes. The adhesive strength after one week is measured by a mechanical tester.

(4) Light transmittance The transmittance was measured at a wavelength of 550 nm (Poic haze meter SEP-HS-D, manufactured by Nippon Seimitsu Kogyo Co., Ltd.).
Type 1).

(5) Number of Foreign Substances in Plastic Film A plastic film sample was 210 mm in length × 14 in width.
8 mm (area 310.8 cm ² ) was cut out, and the whole area of the film was inspected for foreign substances by visual inspection by the cross Nicol method. Next, the detected foreign matter in the sample film was observed with transmitted light using an optical microscope, and the maximum diameter of a portion observed as an optically abnormal range was defined as the size of the foreign matter. In addition, when a cavity (void) existing around the foreign particle is observed as an optically abnormal range, it is included in the size of the foreign particle. Then, the size of the foreign particles was divided into those having a size of 5 μm or more and less than 25 μm and those having a size of 25 μm or more.

(6) Number of surface defects The obtained surface protective film was laminated on a polarizing plate,
The sample was cut out to a size of 0 mm × width 148 mm (area 310.8 cm ² ), and the number was counted under a fluorescent lamp so that the unevenness of the surface could be visually confirmed by the reflected light.

Example 1 2-ethylhexyl acrylate and n-butyl acrylate as main monomers as an acrylic pressure-sensitive adhesive, vinyl acetate as a comonomer, and hydroxyethyl methacrylate as a functional group-containing monomer in a ratio of 4: 3: 2: 1. Further, as an additive, an epoxy-modified stearyl acrylate is added in an amount of 0.5 part to 10 parts of the above-mentioned monomers, and azobisisobutyronitrile is used as a reaction catalyst in a solvent of ethyl acetate. The polymer was polymerized to prepare a pressure-sensitive adhesive polymer having a weight average molecular weight of about 450,000. Next, an intrinsic viscosity of 0.6% containing 0.1% by weight of true spherical silica particles having an average particle size of 0.15 μm.
The polyethylene terephthalate polymer of No. 2 was melted by an extruder, and was adhered to a rotating cooling drum maintained at 40 ° C. from a die by using an electrostatic adhesion method, and rapidly cooled to obtain an unstretched film. Next, this unstretched film was stretched 3.5 times in the machine direction and then 3.6 times in the transverse direction, and heat-set at 220 ° C. to obtain a biaxially oriented polyethylene terephthalate film having a thickness of 50 μm. further,
Corona treatment was performed on both sides of this film. Next, on one side of this film, a first layer of an antistatic layer was provided as a protective layer, and a release layer was provided as a second layer. As the antistatic layer, 30 parts of a thiophene derivative polymer, copolyester 7
0 parts (60 mol% of terephthalic acid, 35 mol% of isophthalic acid, 5 mol% of adipic acid as a dicarboxylic acid component, 95 mol% of ethylene glycol as a glycol component,
A 3% aqueous coating solution composed of 5 parts by mole of diethylene glycol) and 5 parts of a nonionic surfactant was applied to form a coating film having a thickness of 0.15 μm after drying. As the release layer, 40 parts of polyethyleneimine octadecyl carbamate (RP-20, manufactured by Nippon Shokubai Co., Ltd.), and as a binder component, as in the case of the antistatic layer, a polyester-based polyester resin (Espel 1 manufactured by Hitachi Chemical Co., Ltd.)
510) 100 parts and a coating liquid obtained by mixing 30 parts of melamine resin (Nikarac NS-11, manufactured by Sanwa Chemical Co., Ltd.) is applied, dried and cured at 140 ° C. for 1 minute, and cured to a thickness of 0.2 μm. Was formed. Next, a TDI-based isocyanate cross-linking agent is added to the above-mentioned pressure-sensitive adhesive polymer, and the thickness of the film after drying is 20 μm on the surface opposite to the protective layer.
μm, dried at 100 ° C for 2 minutes, rolled up,
Aging treatment was performed at 45 ° C. for one week to obtain a sample.
Table 1 shows the properties of the laminated film.

Comparative Example 1 In Example 1, an adhesive was applied to the opposite surface of the antistatic layer without providing a release layer, and was wound up.

[Comparative Example 2] In Example 1, the particles to be contained in the polyethylene terephthalate polymer having an intrinsic viscosity of 0.61 were used as the base material of the surface protective film in the form of spherical silica particles having an average particle diameter of 0.5 μm. A plastic film was prepared in the same manner except that the amount was 5% by weight.
A laminated film was made. The characteristics are shown in Table 1.

Comparative Example 3 A sample was prepared in the same manner as in Example 1, except that the biaxially oriented polyethylene terephthalate film was changed to a polyethylene film as a substrate of the surface protective film. The characteristics are shown in Table 1. As the polyethylene film, a 50 μm-thick film formed by inflation of polyethylene resin having a density of 0.925 and a melt index of 2.5 was used after corona treatment.

[0052]

[Table 1] ----------- ----------------------------------- ------------------ Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 -------------------- -------------------------------------------- Plastic film PET PET PET PE Peeling force (mN / 25mm) 150 1100 200 120 Normal adhesive force (mN / 25mm) 120 600 110 110 後 After lapse of one week at 60 ° C 140 1000 120 130 Change rate of normal adhesive force 1.2 1.7 1.1 1 0.2 Number of foreign substances on the surface protective film 25 μm or more (pieces) 0 515 15 Less than 25 μm (pieces) 3 4 12 10 Light transmittance (%) 85 82 82 65 Haze (%) 6 7 7 12 12 Number of surface defects (pieces) 0 0 8 18 Defect Inspection ○ × × × ---------------------------------------- ------------------------

As is evident from Table 1, the surface protective film of the present invention shown in the examples forms an adhesive layer without using a release paper, and is easily peeled off at the time of use, and is applied to a mating substrate. It can be laminated, can be peeled off lightly if necessary, and does not become heavy even after aging, and is highly transparent and does not impair the testability of the laminated mating substrate. .

[0054]

The surface protective film of the present invention can form an adhesive without using release paper, can be easily peeled off from a roll at the time of use, and can be used at the time of manufacturing a liquid crystal display-related component such as a polarizing plate. , Because of its low adhesive strength and small change over time, it improves productivity, yield, etc.,
In addition, by using a polyester film having few foreign substances as a base material, transparency can be improved and testability can be improved. Further, by providing an antistatic treatment or a release treatment on the opposite surface of the pressure-sensitive adhesive layer, it is easy to suppress the charge at the time of peeling and to remove dust and the like on the surface.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 4F100 AH03 AH03H AH04 AH04H AK22 AK22J AK25 AK25J AK36 AK41A AK42 AK51 AL01 AR00B AR00C AS00C BA03 BA07 BA10B BA10C CA22C CA23A CA30C DE01A EJ38AJJJ EJ38AJJBJ JBJJBJJBJJBJJBJ JN08C YY00 YY00A YY00B 4F210 AA24 AC03 AD08 AG01 AG03 AH33 QC05 QW07 QW34 QW50

Claims (2)

[Claims] An adhesive layer (B) is provided on one side of a biaxially oriented polyester film (A), and a protective layer (C) is provided on the other side of the biaxially oriented polyester film. A film roll obtained by bringing the layer (C) into contact with and winding up the film roll, wherein the film roll satisfies all of the following conditions (1) to (6). (1) The biaxially oriented polyester film (A) has no foreign matter having a size of 25 μm or more per area (area: 310.8 cm ² ) having a side length of 210 mm and a side length of 148 mm perpendicular thereto. (2) In the biaxially oriented polyester film (A), a size of 5 μm or more per 210 mm in side length and 148 mm in side length (area of 310.8 cm ² ) perpendicular to it, 2
There are only at most 10 foreign particles of less than 5 μm. (3) The protective layer (C) contains a release agent and an antistatic agent. (4) The peeling force when peeling the protective layer (C) from the pressure-sensitive adhesive layer (B) is 10 mN / 25 mm or more and 1000 mN / 25 m.
m or less. (5) The adhesive strength of the pressure-sensitive adhesive layer (B) to the stainless steel plate is 30 mN / 25 mm or more and 500 mN / 25 mm or less.
5 times or more and 2 times or less. (6) The thickness of the pressure-sensitive adhesive layer (B) is 3 μm or more and 50 μm or less. 2. The visible light transmittance of the surface protective film is 7
The film roll according to claim 1, wherein the haze is 0% or more and the haze is 10% or less.