JP7138501B2 - antifouling film - Google Patents

Description

TECHNICAL FIELD The present invention relates to an antifouling film, a roll thereof, and a storage box for the roll.

Dedicated covers for keyboards have been proposed to protect personal computer keyboards from water, dust, and the like to prevent failures. For example, Patent Literature 1 proposes a keyboard cover having an adhesive elastomer film at a portion that contacts the keyboard. This keyboard cover can prevent slippage from the keyboard and deformation of the cover due to slippage due to its adhesive properties. Further, for example, Patent Document 2 proposes a silicone elastomer sheet having a specific surface roughness, thickness, and rubber hardness, which prevents slippage without an adhesive, and provides a good feel to the fingers when touching keys, providing a comfortable typing feeling. It improves and can be easily removed.

In addition, in the medical field, personal computers such as electronic medical records are shared by a plurality of medical personnel, so cross-infection is a concern, and it is required to maintain hygiene. On the other hand, Patent Document 3, for example, proposes a keyboard cover molded from a resin containing an antibacterial agent.

Registered Utility Model No. 3032087 JP 2007-058297 A JP 2006-330954 A

However, in the prior art, although the keyboard cover could be prevented from slipping from the keyboard, it could peel off from the edges in busy medical settings if the adhesive strength was not adequate. If the cover peels off at a medical site, the purpose of infection prevention cannot be achieved. On the other hand, if the keyboard is firmly attached to the keyboard with double-sided tape or the like to prevent detachment, a problem arises in that the load resistance (hereinafter also referred to as "keying resistance") that presses the buttons of the keyboard increases. If the keystroke resistance increases, the usability of the keyboard will decrease, and incomplete input errors will occur due to the buttons not being pressed down, and keys around the touched key will follow and be pressed, resulting in erroneous input errors. There is concern that

The present invention has been made in view of the above problems, and provides an antifouling film and an antifouling film that can make it difficult to reduce the operability of an input unit having a push button caused by attaching the film. An object of the present invention is to provide a roll and a storage box for the roll.

As a result of extensive studies, the inventors of the present invention have found that the above problems can be solved by reducing the keystroke resistance, and have completed the present invention.

That is, the present invention is as follows.
[1]
An antifouling film having a base film and an adhesive layer partially disposed on the base film,
The 2% strain tensile load in the machine direction (MD direction) and width direction (TD direction) of the antifouling film is independently 0.8 to 1.6 N/cm 100 mm ,
The adhesive strength of the partially arranged adhesive layer (JIS0237 compliant 180 degree peel strength) is 0.01 to 0.5 N / 25 mm,
antifouling film.
[2]
The coverage area ratio of the adhesive layer covering the base film is 5 to 90 area%,
The antifouling film according to [1].
[3]
When the antifouling film is arbitrarily cut into 5 cm × 5 cm squares, the adhesive layer covering the base film has a coverage area ratio of 5 to 90 area%.
The antifouling film according to [1] or [2].
[4]
Haze of the base film is 0.1 to 25%,
[1] The antifouling film according to any one of [3].
[5]
A film for covering the surface of the input unit having a push button,
[1] The antifouling film according to any one of [4].
[6]
Equipped with a core tube and the antifouling film according to any one of [1] to [5] wound around the core tube,
Antifouling film roll.
[7]
The drawing force as a whole width is 10 to 300 cN / 220 mm,
The antifouling film roll according to [6].
[8]
[6] or [7], having the antifouling film roll and a box for storing the antifouling film roll,
the box comprises a cutting tool for cutting the antifouling film;
Dirt prevention film storage box.

ADVANTAGE OF THE INVENTION According to this invention, the dirt prevention film which can make it hard to produce the operability deterioration of the input part which has a push button which arises by sticking a film can be provided.

Sectional view of a pantograph type key used in a notebook computer. Graph showing relationship between stroke increase and load. It is a figure which shows the pattern of the adhesion layer in the dirt prevention film of this embodiment. It is a figure which shows the pattern of the adhesion layer in an Example.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to this embodiment. And, the present invention can be appropriately modified and implemented within the scope of the gist thereof. In addition, unless otherwise specified, the measurement of each physical parameter in this embodiment is performed under normal temperature and normal pressure.

[dirt prevention film]
The antifouling film of the present embodiment has a base film and an adhesive layer partially disposed on the base film, and the machine direction (MD direction) and width direction (TD direction) of the antifouling film ) is independently 0.8 to 1.6 N / cm 100 mm , and the adhesive strength of the adhesive layer (JIS0237 compliant 180 degree peel strength) is It is 0.01 to 0.5N/25mm.

In the present embodiment, the "anti-fouling film" is, for example, a film for covering the surface of an input unit having push buttons, and is used by being attached to the input unit of a personal computer or various devices having a control panel. be. The antifouling film is temporarily attached to the surface of the input section having the push buttons, and after a certain period of use, it is peeled off and discarded from the viewpoint of cleanliness. More specifically, by attaching the antifouling film to electronic medical record keyboards and various examination equipment with operation panels that are in contact with multiple medical personnel in the hospital, it is possible to prevent the adhesion of bacteria and viruses, blood , vomit, and other bodily fluids from coming into direct contact with the product. cross-infection between individuals can be prevented. Of course, the use is not limited to the medical field. It is also possible to suppress the occurrence of defects and failures.

Further, the antifouling film of the present embodiment is a film having no unevenness, and is different from, for example, a cover having unevenness corresponding to the unevenness of the buttons of a keyboard. By having such a shape, the antifouling film of this embodiment can take the form of a roll, which will be described later, and can be housed in a storage box and distributed.

Next, the operation of the push button will be described using an example, but the use of the antifouling film of the present embodiment is not limited to this example. FIG. 1 shows a cross section of a pantograph type key used in a notebook computer. A pantograph-type key 10 has a structure in which a key top 2 and a switch input portion 3 face each other with a pantograph structure 1 interposed therebetween. An elastic member 4 is arranged between the key top 2 and the switch input portion 3 to apply an upward biasing force to the key top 2 in a direction away from the switch input portion 3 . The inside of the lower side of the elastic member 4 is hollow, and a downward pressing projection 4a is integrally formed in this hollow.

When the user presses the keytop 2, the elastic member 4 is crushed by the keytop 2 as the stroke increases, and the switch input section 3 is pressed by the pressing protrusion 4a, thereby obtaining a key input signal. As shown in FIG. 2, looking at this from the relationship between the stroke increase and the load, as the stroke increases, the elastic member 4 elastically deforms and the load increases (arrow 1), and when the load reaches the peak load (FP) When the elastic member 4 buckles and the load decreases (arrow 2), the user feels a click feeling, and when the stroke reaches the on-stroke (SO), the pressing convex portion 4a contacts the switch input portion 3, and a signal is generated. is transmitted. When the user further pushes the keytop 2 after the on-stroke, the load increases (arrow 3).

On the other hand, when the user pushes the key top 2 with the antifouling film stuck on the surface of the push button, the antifouling film becomes taut and resistance occurs. This becomes a keystroke resistance and increases the load during the on-stroke (SO). As a result, the usability of the keyboard deteriorates, and incomplete input errors occur because the buttons are not pressed. In addition, the dirt-preventing film in the part where the key top 2 is pushed in is pulled by the dirt-preventing film in contact with the adjacent button, which may cause the adjacent button to follow and be pressed, which is also a cause of erroneous input errors. Become.

In addition to the fact that the anti-smudge film does not stretch easily, the anti-smudge film sticks to the surface of the button. An adhesive layer is provided on the push button contact surface of the antifouling film so that the purpose of protecting the input section from contamination is not achieved due to displacement and peeling from the input section. However, this adhesive layer is arranged on the front surface of the antifouling film, and the antifouling film is fixed to the surface of the button between the adjacent push buttons, which is thought to increase the keying resistance. On the other hand, in the antifouling film of the present embodiment, by having an adhesive layer partially arranged on the base film, deterioration in the usability of the keyboard is suppressed, and the antifouling film can be attached. It is possible to suppress non-input errors and erroneous input errors caused by Moreover, on the other hand, it is possible to reduce the momentum when pushing the key top, and to suppress the typing sound caused by the contact and friction of each member.

The input unit having a push button is not particularly limited as long as it is an input unit of an electronic device having a key switch (push button). Examples include push buttons of electronic devices such as appliances and push buttons of remote controls of televisions and the like. The push button is not particularly limited, but includes, for example, a mechanical switch, a membrane switch, a pantograph switch, and a capacitance non-contact type switch, depending on the difference in mechanism.

The 2% strain tensile load in the machine direction (MD direction) and the 2% strain tensile load in the width direction (TD direction) of the antifouling film of the present embodiment are each independently 0.8 to 1.6 N / cm · 100 mm , preferably 0.8 to 1.5 N/cm·100 mm , more preferably 0.8 to 1.4 N/cm ·100 mm . Operability tends to be further improved when the 2% strain tensile load is within the above range. The 2% strain tensile load can be adjusted by adjusting the thickness of the base film, the thickness of the adhesive layer, and the coating area ratio of the adhesive. The 2% strain tensile load in the machine direction (MD direction) and width direction (TD direction) of the antifouling film can be measured by the method described in Examples below.

[Base film]
The 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) of the base film are each independently preferably 190 to 550 MPa, more preferably 200 to 500 MPa, and still more preferably 200 to 400 MPa. When the 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) are within the above ranges, operability tends to be further improved. Furthermore, the antifouling film tends to be prevented from being partially stretched.

The 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) of the base film is controlled by selecting the type and grade of resin to be used, the formulation of additives, and adjusting the processing conditions accordingly. be able to. The 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) of the base film can be measured by the method described in Examples below.

In addition, the tensile elongation in the machine direction (MD direction) and width direction (TD direction) of the base film is each independently preferably 60 to 200%, more preferably 70 to 180%, and still more preferably. is 90-160%. When the tensile elongation in the machine direction (MD direction) and the width direction (TD direction) of the base film is within the above range, it tends to be difficult to cause deterioration in operability.

The tensile elongation in the machine direction (MD direction) and width direction (TD direction) of the base film can be controlled by selecting the type and grade of resin to be used, the formulation of additives, and adjusting the processing conditions accordingly. . The tensile elongation in the machine direction (MD direction) and the width direction (TD direction) of the base film can be measured by the method described in Examples below.

Components constituting the base film are not particularly limited, but examples include polyvinylidene chloride; polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; ethylene/vinyl alcohol copolymers; Coalescence; Polyamide; Polyurethane and the like. Among these, polyvinylidene chloride and polyolefins are preferable, and polyvinylidene chloride is more preferable. In addition, the component which comprises a base film may be used individually by 1 type, and may be used in combination of 2 or more types.

(polyvinylidene chloride)
Polyvinylidene chloride includes vinylidene chloride homopolymers and vinylidene chloride copolymers of vinylidene chloride monomers and monomers copolymerizable therewith. The monomer copolymerizable with the vinylidene chloride monomer (hereinafter sometimes referred to as "comonomer") is not particularly limited, but examples include vinyl chloride; acrylic acid esters such as methyl acrylate and butyl acrylate; acrylic acid; methacrylic acid esters such as methyl methacrylate and butyl methacrylate; methacrylic acid; methyl acrylonitrile; These copolymerizable monomers may be used singly or in combination of two or more.

The weight average molecular weight (Mw) of the polyvinylidene chloride copolymer is preferably 5×10 ⁴ to 1.5×10 ⁵ , more preferably 6×10 ⁴ to 1.3×10 ⁵ , still more preferably. is between 7×10 ⁴ and 1×10 ⁵ . A weight-average molecular weight (Mw) of 5×10 ⁴ or more tends to further improve the melting properties during extrusion. Further, when the weight average molecular weight (Mw) is 1.5×10 ⁵ or less, melt extrusion tends to be possible while maintaining thermal stability. In the present embodiment, the weight average molecular weight (Mw) can be determined by gel permeation chromatography (GPC method) using a standard polystyrene calibration curve.

The base film may be a stretched film or an unstretched film, but is preferably a stretched film. Stretched films tend to have higher stress resilience and smaller hysteresis loss than unstretched films. Generally, in the case of a film having a small restoring force against stress, when a certain amount of stress is applied, that portion stretches and does not return to its original shape. For example, in the case of pressing a key with an antifouling film attached to the keyboard, stress is temporarily applied to the antifouling film near the keys that have been pressed, but the stretched film has high resilience. In the case of , the antifouling film in the vicinity of the pressed key can be easily restored to its original state, and it is possible to prevent the antifouling film from being completely stretched.

Whether or not the base film is a stretched film can be determined by the heat shrinkage rate at high temperatures. In the present embodiment, the stretched film is qualitatively defined as having a shrinkage of 20% or more when left standing at 120° C. for 10 minutes. Such a stretched film has little hysteresis loss and high restorability when used repeatedly. Thus, the higher the resilience, the better the feeling of operation during use. On the other hand, if the film is completely stretched without being restored, it may cause typing errors, or the stretched portion may get caught in the push button and break the film.

(Other additives)
In addition to the above resins, which are the main component of the base film, if necessary, other additives such as known plasticizers, heat stabilizers, colorants, organic lubricants, inorganic lubricants, surfactants, processing aids, etc. It may contain a drug.

Examples of plasticizers include, but are not limited to, acetyltributyl citrate, acetylated monoglyceride, dibutyl sebacate, and the like.

Examples of heat stabilizers include, but are not limited to, epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil, epoxy resins, magnesium oxide, and hydrotalcite.

(Haze)
The haze of the base film is preferably 0.1 to 25%, more preferably 0.1 to 20%, still more preferably 0.1 to 10%. When the haze of the base film is within the above range, the visibility of the keys is further improved, and erroneous input tends to be prevented. The haze of the base film can be adjusted depending on the type of resin used and the thickness of the base film. Also, Haze can be measured according to ASTM D-1003.

(thickness)
The thickness of the base film is preferably 5 to 60 μm, more preferably 7 to 50 μm, still more preferably 10 to 40 μm. When the thickness of the base film is within the above range, the operability and tear resistance tend to be further improved.

[Adhesive layer]
The antifouling film of this embodiment has an adhesive layer partially disposed on the base film. FIG. 3 shows an example of the pattern of the adhesive layer in the antifouling film of this embodiment.

The adhesive strength of the partially arranged adhesive layer (JIS Z0237 compliant 180 degree peel strength) is 0.01 to 0.5 N/25 mm, preferably 0.02 to 0.3 N/25 mm, more preferably It is 0.03 to 0.2N/25mm, more preferably 0.03 to 0.1N/25mm. Here, the "adhesive strength of the partially disposed adhesive layer" is not the adhesive layer disposed on the entire surface of the base film, but includes the portion where the adhesive layer is disposed and the portion where the adhesive layer is not disposed. It means the adhesive strength of the antifouling film. In this sense, the "adhesive strength of the adhesive layer partially disposed" is lower than the adhesive strength when the adhesive layer is disposed on the entire surface of the base film. If the adhesive layer is partially arranged, the part that does not stick to the key top becomes play, reducing the resistance when the user pushes the key top in, suppressing the increase in load during the on-stroke. , it is possible to suppress non-input errors and erroneous input errors. Therefore, even if the "adhesive strength of the partially applied adhesive layer" and the adhesive strength of the adhesive layer distributed over the entire surface are equivalent, the entire surface does not have any loose parts that do not stick to the key top. The above effects cannot be expected from the adhesive layer provided. In the present embodiment, the adhesive layer is not arranged on the entire surface of the base film, and the adhesive strength of the adhesive layer that is partially arranged is within a predetermined range. In addition, it is possible to make it difficult for the operability of the input unit having push buttons to deteriorate. The method for controlling the adhesive strength of the adhesive layer within the above range is not particularly limited. Examples thereof include a method of adjusting the coverage area ratio of the adhesive layer, and a method of adjusting the hardness of the adhesive and the thickness of the adhesive layer. be done. In this embodiment, the adhesive strength of the adhesive layer is the maximum value of the 180-degree peel strength obtained by a measuring method conforming to JIS0237. (The minimum value when measuring the 180 degree peel force of the adhesive film in which the adhesive layer is partially arranged is 0 when the adhesive layer is not present in the lateral direction, and the average value including such numerical values is It has no technical meaning in this embodiment.)

On the other hand, when the adhesive layer of the present embodiment is temporarily placed on the entire surface, the adhesive strength (hereinafter also referred to as "adhesive strength of the adhesive layer itself" (180 degree peel strength according to JIS 0237)) is 0.05 to 1.0. It is 0 N/25 mm, preferably 0.08 to 0.8 N/25 mm, more preferably 0.1 to 0.5 N/25 mm. Since the adhesive strength of the adhesive layer itself is within the above range, even when the adhesive layer is partially arranged, the balance of sticking to the adherend and peelability is excellent, and the input part having a push button is improved. It tends to be possible to further suppress deterioration in operability.

As a form of the adhesive layer partially disposed on the base film, the formation range of the adhesive layer can be represented by the covering area ratio of the adhesive layer covering the base film. The coverage area ratio of the adhesive layer is preferably 5 to 90 area%, more preferably 10 to 80 area%, and still more preferably 15 to 70 area% with respect to the total area of one base film. be. When the coverage area ratio of the adhesive layer covering the base film is within the above range, even when the adhesive layer is partially arranged, the balance of adhesion to the adherend and peelability is excellent, and the push button can be easily operated. It tends to be possible to further suppress deterioration of the operability of the input unit.

In addition, when the antifouling film is arbitrarily cut into 5 cm × 5 cm squares, the coverage area ratio of the adhesive layer covering the base film is preferably 5 to 90 area%, more preferably 10 to 80 area%. Yes, more preferably 15 to 70 area %. The coverage area ratio of the adhesive layer covering the substrate film when arbitrarily cut into 5 cm×5 cm squares is an index showing that the coating layer is formed dispersedly on the substrate film. When the adhesive layer covering the base film is arbitrarily cut into 5 cm × 5 cm squares, the coverage area ratio of the adhesive layer covering the base film is within the above range, so that even when the adhesive layer is partially arranged, the sticking property to the adherend , the balance of peelability is excellent, and the deterioration of the operability of an input unit having a push button tends to be suppressed.

In addition, when the adhesive layer is arranged in dots on the base film as shown in FIG. , preferably 2 or more, more preferably 4 or more, still more preferably 10 or more. As the number of push buttons increases, the areas where the adhesive layer does not exist and the areas where the adhesive layer exists are dispersed, and the variation in operability for each push button tends to be more suppressed. For this reason, the upper limit of the number of adhesive layers is not particularly limited, but is preferably 1000 or less, more preferably 700 or less, from the viewpoint of production. Note that the dot-like means that one dot-like adhesive layer fits within a range of 2 cm × 2 cm at the most, and the shape is not particularly limited, and is, for example, circular, approximately circular, semicircular, approximately semicircular. , elliptical, approximately elliptical, semi-elliptical, approximately semi-elliptical, and polygonal.

Furthermore, when the adhesive layer is arranged in a grid pattern on the base film as shown in FIG. In this case, the number of regions in which the adhesive layer does not exist in a dot shape per unit area (5 cm × 5 cm) of the base film is preferably 1 or more, more preferably 5 or more, More preferably, the number is 10 or more. As the number of push buttons increases, the areas where the adhesive layer does not exist and the areas where the adhesive layer exists are dispersed, and the variation in operability for each push button tends to be more suppressed. For this reason, the upper limit of the number of areas where the adhesive layer does not exist is not particularly limited, but it is preferably 1000 or less, more preferably 700 or less from the viewpoint of manufacturing. In this case, the point shape means that one point is within the range of 5 cm × 5 cm at the most, and the shape is not particularly limited, for example, circular, approximately circular, semicircular, approximately semicircular, elliptical Shapes include substantially elliptical, semi-elliptical, substantially semi-elliptical, and polygonal.

Further, when the adhesive layer is linearly arranged on the base film as shown in FIG. It will be done. In this case, the width of the area where the adhesive layer exists (the distance between the areas where the two adhesive layers do not exist) and the width of the area where the adhesive layer does not exist (the distance between the areas where the two adhesive layers exist ) is preferably from 1:0.05 to 1:20, more preferably from 1:0.1 to 1:10.

The adhesive that forms the adhesive layer is not particularly limited, but examples thereof include urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, silicone-based adhesives, and ethylene/vinyl acetate adhesives. In order to cover the surface of the input section with push buttons, it is temporarily attached, and after a certain amount of use, it is peeled off and discarded from the viewpoint of cleanliness. It is preferred that the adhesive strength be such that it can be peeled off by pressing and that the peelability is excellent so that no adhesive remains on the surface to which it is adhered. In addition, even if the antifouling film sticks to each other on the adhesive layer surfaces, the antifouling film having such adhesiveness can be easily untangled, so that it is easier to handle. From such a point of view, among the above adhesives, urethane-based adhesives, silicone-based adhesives, and acrylic-based adhesives are preferable, and urethane-based adhesives are more preferable.

Urethane-based adhesives are adhesives made of polyurethane obtained by condensation of compounds having an isocyanate group and a hydroxy group, and have excellent air release properties during application work and excellent removability that can be peeled off without adhesive residue. There is a tendency. The urethane-based pressure-sensitive adhesive is not particularly limited, but examples thereof include polyether-based polyurethane, polyester-based polyurethane, and the like.

A silicone pressure-sensitive adhesive is a pressure-sensitive adhesive composed of a polymer having a siloxane bond as a main skeleton, has a wide range of usable temperatures, and tends to be excellent in air release during application.

Acrylic pressure-sensitive adhesives are pressure-sensitive adhesives made of (meth)acrylic polymers. Comonomers are added to the main monomer to adjust the cohesive force, and functional group-containing monomers are added to provide cross-linking points for adhesion. The hardness of the agent can be adjusted to develop the desired adhesive strength. The main monomer used in the acrylic pressure-sensitive adhesive is not particularly limited, but examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and the like. Various alkyl (meth)acrylates can be mentioned, and these can be used alone or in combination. Examples of comonomers include, but are not limited to, vinyl acetate, acrylonitrile, acrylamide, and styrene. Examples of functional group-containing monomers include, but are not particularly limited to, acrylic acid, hydroxyethyl acrylate, acrylamide, glycidyl methacrylate, and the like.

Furthermore, tackifying resins such as rosin, terpenes, aliphatic and aromatic synthetic resins can be added to the adhesive layer to adjust the adhesive force. In addition, stabilizers, antioxidants, light stabilizers, UV absorbers, and the like may be added to the adhesive layer.

The thickness of the adhesive layer is preferably 1 to 30 μm, more preferably 3 to 25 μm, still more preferably 5 to 25 μm, from the viewpoint of adhesive strength of the adhesive layer. When the thickness of the adhesive layer is within the above range, the effect of sticking firmly to the keyboard and being easily peeled off tends to be more pronounced.

[Release layer]
The antifouling film of this embodiment may further include a release layer on the back surface of the base film (the surface on which the adhesive layer is not formed). Including the release layer tends to make it easier to pull out the antifouling film when formed into a roll. The component that forms the release layer is not particularly limited, and examples thereof include silicone-based resins and long-chain alkyl pendant polymer-based resins.

The long-chain alkyl pendant polymer-based resin is not particularly limited, but may Examples include long-chain alkyl-modified polymers obtained by reacting long-chain alkyl components such as alkyl isocyanate. By providing such a release layer, the antifouling film tends to maintain its fixability to a keyboard or the like, and at the same time, the drawability of the wound body tends to be further improved.

The thickness of the release layer is preferably 0.1 to 1.0 μm, more preferably 0.15 to 0.9 μm, still more preferably 0.2 to 0.7 μm. By setting the coating thickness of the release layer within the above range, there is a tendency that the drawability of the wound body is further improved.

[Other layers]
Furthermore, the antifouling film of the present embodiment may be provided with a printed layer or a primer layer. For the protection of the adhesive layer and the convenience of attachment to the adherend, a release paper or a release resin film may be attached to the adhesive layer as long as the effects of the present invention are not impaired.

[Thickness]
The total thickness of the antifouling film of the present embodiment is 10-80 μm, preferably 15-70 μm, more preferably 20-60 μm. When the thickness is within the above range, the flexibility is further improved. Also, if it is too thick, it will be difficult to input keys when used as a keyboard cover.

[Method for producing antifouling film]
The method for producing the antifouling film of the present embodiment is not particularly limited as long as it is a method capable of forming an adhesive layer on the substrate film.

As a method for obtaining the substrate film, for example, a method comprising a step of extruding a resin from an annular die as a monolayer or multi-layer material and a step of cooling and solidifying the extruded material can be mentioned. In addition, if necessary, known additives such as a plasticizer, an antioxidant, and a stabilizer may be blended with the resin.

When the substrate film is a stretched film, it has a stretching step of stretching the substrate film extruded from the die in the MD direction and the TD direction. The stretching method may be uniaxial stretching or biaxial stretching. As a specific method of biaxial stretching, a sequential or simultaneous biaxial stretching method or an inflation biaxial stretching method can be employed. Specifically, the stretching in the TD direction is performed by the internal pressure of air injected into the unstretched tube by a bubble inflation method or the like, and the stretching in the MD direction is performed by an unstretched tube provided upstream of the TD stretching section. This can be done by adjusting the speed ratio between the roll for sending out the stretched tube and the roll for winding up the stretched laminated tube provided downstream. As another method, stretching in the TD direction when using an unstretched film is performed by applying tension in the width direction of the unstretched film using a pinch clip by a tenter method or the like, and stretching in the MD direction. can be carried out by adjusting the speed ratio between the unstretched film feeding roll provided upstream of the TD stretching section and the stretched film winding roll provided downstream.

The draw ratio at this time is preferably 2.5 to 7.5 in both the MD direction and the TD direction.

The antifouling film of the present embodiment can be obtained, for example, by applying an adhesive to the base film obtained as described above with a comma coater or gravure coater, drying, winding, and aging at 40 ° C. for 2 days. can. Before applying the adhesive, a primer having an affinity to the adhesive layer and the substrate layer may be applied in advance, or corona treatment, plasma treatment, or the like may be performed to adjust the surface tension of the substrate film. In addition, a release layer may be formed on the back surface of the base film in steps before and after the adhesive coating.

[Stain prevention film roll]
The antifouling film roll of the present embodiment includes a core tube and the antifouling film wound around the core tube.

(Core tube)
The material of the core tube is not limited, and for example, materials such as paper, plastic, and metal can be used. The core tube may be a hollow cylindrical body or a solid cylindrical body. Also, the diameter of the core tube is not limited, and can be, for example, 10 mm to 50 mm.

The pull-out force for pulling out the antifouling film from the antifouling film roll is preferably 10 to 300 cN/220 mm width, more preferably 15 to 200 cN/220 mm width, still more preferably 20 to 100 cN/220 mm width. . When the pulling force is within the above range, the required amount of antifouling film can be pulled out with a light force.

The method for controlling the pulling force for pulling out the antifouling film from the core tube is not particularly limited, but for example, in addition to setting the adhesive strength of the antifouling film, a release layer is provided on the back of the antifouling film. Things are mentioned.

In addition, in this embodiment, the pull-out force for pulling out the antifouling film from the core tube can be measured by the method described in Examples below.

[dirt prevention film storage box]
The antifouling film storage box of the present embodiment has the antifouling film roll described above and a box for storing the antifouling film roll, and the box has a cutting tool for cutting the antifouling film. Prepare. By storing the antifouling film roll in the box, the required amount of antifouling film can be easily pulled out and cut.

Examples of the cutting tool include, but are not particularly limited to, metal, paper, and plastic saw blades, as well as slide cutters.

EXAMPLES Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, unless otherwise specified, the measurement of each physical parameter in this embodiment is performed under normal temperature and normal pressure.

〔Adhesive force〕
The adhesive strength of the partially arranged adhesive layer was measured as follows according to JISZ0237. That is, a 25 mm wide and 300 mm long sample was cut out of the antifouling film along the MD direction, and attached to a SUS304 mirror-finished plate by reciprocating twice at 10 mm/sec using a 2 kg weight roller. At a speed of 300 mm/min, a tension measurement was performed from the SUS mirror-finished plate in the direction of 180 degrees, and the average value of five measurements was taken as the adhesion value for the maximum peel force. For the measurement, a texture analyzer EZ-S manufactured by Shimadzu Corporation was used. The 180-degree peel strength thus obtained was taken as the adhesive strength of the adhesive layer.

[Thickness]
The film was cut using a microtome, and the cut surface was observed with an optical microscope (Keyence VHX-900) to measure the thickness of the film. This was further measured in the MD direction (unwinding direction) of the film at intervals of 1 m, and finally the average value of 10 points was taken as the thickness of the film. The thickness of the adhesive layer is measured by observing with an optical microscope (Keyence VHX-900) in the same manner as the method for measuring the thickness of the film. Finally, the average value of 10 points was used as the thickness of the adhesive layer.

[Fixability during use]
When the antifouling films obtained in Examples and Comparative Examples were used as a keyboard cover, the fixability of the antifouling film to the keyboard was evaluated by the following evaluation criteria by repeatedly touching the keys and typing random Japanese sentences. evaluated.
(Evaluation criteria)
◯: After typing 2,000 characters, no shift or peeling of the antifouling film from the keyboard was observed.
Δ: When 1500 characters were typed, the antifouling film was displaced or peeled off from the keyboard.
x: When 1000 characters were typed, the antifouling film was displaced or peeled off from the keyboard.

[Visibility: Haze]
The haze of the antifouling film was measured according to JISK7136. Specifically, diffuse transmittance and total light transmittance were measured, and haze was calculated by the following formula. The average value of five measurements was taken as the haze value of the film. A haze meter manufactured by Nippon Denshoku Industries Co., Ltd. was used for the measurement.
Haze (%) = diffuse transmittance/total light transmittance x 100

[2% strain tensile load of antifouling film]
The 2% strain tensile load was measured as follows. That is, the antifouling film of each example is cut out to a width of 10 mm and a length of 100 mm at an arbitrary position along the MD and TD directions to obtain a sample, which is stretched by 2% at a tensile speed of 5 mm / min (i.e., stretched by 2 mm). ) was measured. The average value of five measurements was taken as the value of the 2% strain tensile load in each of the MD and TD directions. Texture Analyzer EZ-S manufactured by Shimadzu Corporation was used as a measuring device.

[Pull out force]
A sample obtained by winding 10 m of a 220 mm wide antifouling film on a paper tube was aged at 28° C. for 1 week. An acrylic cylinder and a steel rod with a diameter of 12 mm are fitted in a rotatable fixture that connects via a bearing, the steel rod is fixed to the tensile tester, and the acrylic cylinder and the antifouling film on the paper tube rotate freely. made it possible. The end of the antifouling film is fixed to a 250 mm wide plate directly connected to the load cell of the tensile tester, and the load generated when the antifouling film is pulled out at a speed of 1000 mm / min is the pull force, and the average of five measurements. The value was taken as the measured value. For the measurement, a texture analyzer EZ-S manufactured by Shimadzu Corporation was used.

[Roll]
The wound appearance of the wound body of the antifouling film obtained in Examples and Comparative Examples was evaluated as follows.
◯: The surface of the wound body is visually and tactilely observed, and is substantially uniform in the width direction.
Δ: The surface of the wound body is visually and tactilely observed, and the surface is slightly uneven in the width direction.
x: Observation of the surface of the wound body by visual and tactile sensation revealed that the surface unevenness was large in the width direction.

[Operability]
When using the antifouling film obtained in Examples and Comparative Examples as a keyboard cover, repeat key touches and type 20,000 random Japanese characters to evaluate whether no input or incorrect input occurs. did. (Evaluation criteria)
◯: 100 characters or less of input errors due to non-input or erroneous input.
△: 101 to 150 characters of input errors due to non-input and erroneous input.
x: 151 characters or more of input errors due to non-input or erroneous input.

[Example 1]
[Production of base film]
Vinylidene chloride-vinyl chloride copolymer (vinylidene chloride monomer unit content/vinyl chloride monomer unit content = 80 mass%/20 mass%, weight average molecular weight 120000, hereinafter referred to as “PVDC”) 100 mass 3 parts by mass of dibutyl sebacate and 3 parts by mass of acetyltributyl citrate as fatty acid esters, and 2 parts by mass of epoxidized soybean oil as an epoxidized compound were added and mixed for 5 minutes with a Henschel mixer. The resulting mixture is extruded into a tubular shape with a melt extruder, supercooled in a cold water bath of about 10 ° C., passed through water of 35 ° C., stretched at 30 ° C., 3.9 times in the longitudinal (MD) direction, 3.9 times in the width (TD ) direction by 4.4-fold inflation biaxial stretching, the tubular film was folded with a pinch roll to prepare a flat and elongated film having a thickness of 42 μm. Then, it was separated into single films using a slitter to obtain a base film of 21 μm.

[Production of antifouling film]
A separator (silicone-treated polyethylene terephthalate (PET) sheet) is coated with a urethane-based adhesive (main agent: Siabain SH-101 (100 parts by mass), curing agent: (5 parts by mass), manufactured by Toyochem Chemical Co., Ltd.) to a cell depth of 250 μm. Using a gravure coater, pattern coating is applied in a dot pattern (φ1 mm circular adhesive is regularly coated vertically and horizontally at intervals of 2 mm, coating area ratio = 9%), and the base film produced above is laminated and wound up, aged at 40 ° C. for 2 days, and then the other side of the base film is coated with a backing treatment agent (Piroil 1050, manufactured by Lion Specialty Chemicals) to delaminate the separator. An anti-soiling film was produced by The thickness of the adhesive layer after delamination was 22 μm.

[Manufacturing of antifouling film roll]
The antifouling film (width: 500 mm, length: 300 m) produced as described above is slit to a width of 220 mm, and the antifouling film is wound on a cylindrical core tube for a length of 10 m in the flow direction. An antifouling film roll (width=220 mm) was produced. In the resulting antifouling film roll, the film pull-out force was 17 cN/220 mm width.

Table 1 shows the physical properties of the base film, adhesive layer, antifouling film, and antifouling film roll thus obtained. The results were excellent in visibility, pull-out properties of the wound body, and keyboard operability.

[Example 2]
Example except that the coating pattern of the adhesive was changed to a dot pattern (circular adhesive of φ 1.2 mm was regularly coated vertically and horizontally at intervals of 2 mm, coating area ratio = 11%). An antifouling film was produced in the same manner as in 1, and an antifouling film roll was produced. The results were excellent in visibility, pull-out properties of the wound body, and keyboard operability.

[Example 3]
Example 1 except that the coating pattern of the adhesive layer was changed to a dot pattern (φ1 mm circular adhesive was regularly coated vertically and horizontally at intervals of 1 mm, coating area ratio = 20%). An antifouling film was produced in the same manner, and an antifouling film roll was produced. The results were excellent in visibility, drawability of the wound body, keyboard operability, and fixability at the time of application.

[Example 4]
Example 1 except that the coating pattern of the adhesive layer was changed to a dot pattern (φ2 mm circular adhesive was regularly coated vertically and horizontally at intervals of 1 mm, coating area ratio = 35%). An antifouling film was produced in the same manner, and an antifouling film roll was produced. The results were excellent in visibility, drawability of the wound body, keyboard operability, and fixability at the time of application.

[Example 5]
Example 1 except that the coating pattern of the adhesive layer was changed to a dot pattern (φ5 mm circular adhesive was regularly coated vertically and horizontally at intervals of 1 mm, coating area ratio = 55%). An antifouling film was produced in the same manner, and an antifouling film roll was produced. The results were excellent in visibility, drawability of the wound body, keyboard operability, and fixability at the time of application.

[Example 6]
Example 1 except that the coating pattern of the adhesive layer was changed to a dot pattern (a circular adhesive with a diameter of 10 mm was regularly coated vertically and horizontally at intervals of 1 mm, the coating area ratio = 65%). An antifouling film was produced in the same manner, and an antifouling film roll was produced. The results were excellent in visibility, drawability of the wound body, keyboard operability, and fixability at the time of application.

[Example 7]
Same as Example 1 except that the coating pattern of the adhesive layer was changed to linear (a linear adhesive with a width of 20 mm was continuously applied to both ends of the wound body, the coating area ratio = 18%). Then, an antifouling film was produced, and an antifouling film roll was produced. Although the winding shape of the wound body was poor, the results were excellent in visibility, ease of drawing out the wound body, and keyboard operability.

[Example 8]
The coating pattern of the adhesive layer is linear + dotted (continuously coating a linear adhesive with a width of 20 mm on both ends of the wound body + circular adhesive with a diameter of 1 mm at intervals of 1 mm between the linear adhesives. An antifouling film was produced in the same manner as in Example 1, except that the film was regularly coated vertically and horizontally (coating area ratio = 34%), and an antifouling film roll was produced. The results were excellent in visibility, drawability of the wound body, keyboard operability, and fixability at the time of application.

[Example 9]
Except for changing the coating pattern of the adhesive layer to a diagonal line (a diagonal adhesive with a width of 20 mm inclined at an angle of 45 degrees with respect to the MD direction is coated at intervals of 50 mm, the coating area ratio = 28%). An antifouling film was produced in the same manner as in Example 1, and an antifouling film roll was produced. Although the winding shape of the wound body was poor, the results were excellent in visibility, ease of drawing out the wound body, and keyboard operability.

[Example 10]
The coating pattern of the adhesive layer is linear + oblique line (a linear adhesive with a width of 20 mm is continuously applied to both ends of the wound body + the linear adhesive is inclined at an angle of 45 degrees with respect to the MD direction. An antifouling film was produced in the same manner as in Example 1, except that the oblique adhesive with a width of 20 mm was applied at intervals of 50 mm and the coating area ratio was changed to 45%, and an antifouling film roll was obtained. manufactured. The results were excellent in visibility, drawability of the wound body, keyboard operability, and fixability at the time of application.

[Example 11]
An antifouling film in the same manner as in Example 1, except that the coating pattern of the adhesive layer was changed to a grid pattern (a 5 mm wide adhesive was applied in a grid pattern at intervals of 30 mm, the coating area ratio = 47%). was manufactured to manufacture an antifouling film roll. Although the winding shape of the wound body was poor, the results were excellent in visibility, ease of drawing out the wound body, and keyboard operability.

[Example 12]
An antifouling film was produced in the same manner as in Example 5 except that the back surface treatment was not performed, and an antifouling film roll was produced. The visibility, drawability of the wound body, fixing property at the time of application, and keyboard operability were good, but the drawability was unsuitable.

[Comparative Example 1]
The coating pattern of the adhesive layer is in the form of dotted holes (parts without adhesive (dotted holes) are partially arranged on the entire surface, and the dotted holes are circular with a diameter of φ 1 mm and are regularly arranged vertically and horizontally at intervals of 1 mm. An antifouling film was produced in the same manner as in Example 1, except that the coated area ratio was changed to 91%, and an antifouling film roll was produced. The visibility, pull-out properties of the wound body, and fixability at the time of application were good, but the keyboard operability was unsuitable.

[Comparative Example 2]
An antifouling film was produced in the same manner as in Example 1, except that the adhesive layer was applied to the entire surface of the base film, and an antifouling film roll was produced. The visibility, pull-out properties of the wound body, and fixability at the time of application were good, but the keyboard operability was unsuitable.

FIG. 4 shows the pattern of the adhesive layer in the example.

The antifouling film of the present invention has industrial applicability, for example, as an interface protective material such as a keyboard cover, especially in the medical field.

Claims (8)

An antifouling film having a base film and an adhesive layer partially disposed on the base film,
The base film is a stretched film,
The 2% strain tensile load in the machine direction (MD direction) and width direction (TD direction) of the antifouling film is independently 0.8 to 1.6 N/cm 100 mm,
The adhesive strength (180-degree peel strength according to JISZ0237) of the partially disposed adhesive layer is 0.01 to 0.5 N/25 mm,
antifouling film. The coverage area ratio of the adhesive layer covering the base film is 5 to 90 area%,
The antifouling film according to claim 1. When the antifouling film is arbitrarily cut into 5 cm × 5 cm squares, the adhesive layer covering the base film has a coverage area ratio of 5 to 90 area%.
The antifouling film according to claim 1 or 2. Haze of the base film is 0.1 to 25%,
The antifouling film according to any one of claims 1 to 3. A film for covering the surface of the input unit having a push button,
The antifouling film according to any one of claims 1 to 4. A core tube and the antifouling film according to any one of claims 1 to 5 wound around the core tube,
Antifouling film roll. The drawing force as a whole width is 10 to 300 cN / 220 mm,
The antifouling film roll according to claim 6. An antifouling film roll according to claim 6 or 7, and a box for storing the antifouling film roll,
the box comprises a cutting tool for cutting the antifouling film;
Dirt prevention film storage box.

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