JP2023040540A - soft adhesive film - Google Patents

Abstract

To provide a soft adhesive film that excels in terms of visibility and glare prevention, and is also easy to bond and allows a button or the like to be easily operated through the bonded film.SOLUTION: A soft adhesive film comprises a substrate film primarily composed mainly of soft resin, and an adhesive layer formed on the surface of the substrate film. The substrate film has a surface roughness (Sa value) of 10-15 μm, the adhesive layer has a surface roughness (Sa value) of 16-30 μm, and the difference in absolute value between the refractive index of the substrate film and the refractive index of the adhesive layer is 0.07 or less.SELECTED DRAWING: None

Description

The present invention relates to flexible adhesive films.

Various devices are used in the medical field, but the blood, body fluids, urine, etc. of patients are scattered, and bacteria, viruses, etc. tend to adhere to the devices. There is concern about cross-infection due to the contact of multiple medical workers with these devices, and it is required to maintain hygienic conditions.

In addition, when these devices are wiped with alcohol or hypochlorite-based chemicals for the purpose of disinfection and sterilization, these devices often break down due to permeation of the chemicals.

In order to prevent such cross-infection and failure, for example, Patent Literature 1 proposes an adhesive film in which the film is an adhesive roll. The adhesive film described in Patent Document 1 can be attached to any device due to its adhesiveness, and can be used after being cut into a desired size according to the size of the device because it is a roll. . However, when the adhesive film as described in Patent Document 1 is attached, the adherend may glare and become difficult to see by reflecting light such as shadowless lights and room lights in the operating room. . Especially when it is attached to the monitor, the characters on the screen tend to be difficult to see.

As a technique for preventing such glare, for example, Patent Literature 2 proposes a technique for intentionally forming surface unevenness by mixing fine particles into the film surface to scatter reflected light. Alternatively, for example, Patent Document 3 proposes a technique for preventing glare by using a material with a low refractive index as a film material.

JP 2018-177998 A JP-A-9-251101 Japanese Patent No. 4269510

However, in the film as described in Patent Document 2, the microparticles have low resistance to chemicals such as alcohol and hypochlorite, and the microparticles tend to come off when wiped with a chemical cloth. Also, the low refractive index material used in the film described in Patent Document 3 is generally expensive.

Furthermore, since the films described in Patent Documents 2 and 3 use a hard resin such as polyester resin as a base film, for example, the operation of pressing a button or key tab after attaching such a film can be performed. tends to be difficult.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a soft adhesive film which is excellent in visibility and anti-glare properties, and which is easy to apply and easy to operate, such as a button, etc., from the surface of the applied film.

As a result of extensive research, the present inventors have found that in a soft adhesive film containing a base film and an adhesive layer containing a soft resin as a main component, the surface roughness of the base film side and the adhesive layer side, and the base material The inventors have found that the above problems can be solved by setting the refractive index difference between the film and the adhesive layer to specific ranges, respectively, and have completed the present invention.

That is, the present invention is as follows.
[1]
A base film containing a soft resin as a main component, and an adhesive layer formed on the surface of the base film,
The surface roughness (Sa value) of the base film is 10 to 15 μm,
The surface roughness (Sa value) of the adhesive layer is 16 to 30 μm,
A soft adhesive film, wherein the absolute value of the difference between the refractive index of the base film and the refractive index of the adhesive layer is 0.07 or less.
[2]
The soft adhesive film according to [1], wherein the 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) of the soft adhesive film is 10 to 500 MPa.
[3]
The soft adhesive film according to [1] or [2], wherein the soft resin is a resin containing a polyethylene-based resin as a main component.
[4]
The flexible adhesive film according to [1] or [2], wherein the flexible resin is a resin containing a polypropylene-based resin as a main component.
[5]
The soft adhesive film according to any one of [1] to [4], wherein the base film has a thickness of 10 to 80 μm.
[6]
The flexible adhesive film according to any one of [1] to [5], wherein the adhesive layer contains a urethane-based adhesive.
[7]
The soft adhesive film according to any one of [1] to [6], which has a HAZE value of 15 to 30%.
[8]
The soft adhesive film according to any one of [1] to [7], wherein the GLOSS value measured on the surface side of the base film is 10 to 50%.
[9]
The soft adhesive film according to any one of [1] to [8], wherein the surface of the adhesive layer is covered with a release sheet.
[10]
A method for producing a soft adhesive film according to any one of [1] to [9],
a step of temporarily forming an adhesive layer by applying an adhesive to the release surface of the release sheet;
and laminating a base film on the adhesive layer,
The release sheet has a surface roughness (Sa value) of 5 to 13 μm, and the thickness of the adhesive layer temporarily formed on the release surface is 50 to 250% of the surface roughness (Sa value) of the release sheet. A method for producing a flexible adhesive film, which ranges from
[11]
A soft adhesive film roll comprising a core tube and the soft adhesive film according to any one of [1] to [9] wound around the core tube.
[12]
A box containing the soft adhesive film roll according to [11],
a main body having at least a front plate, a bottom plate, a rear plate and a side plate, and having an open upper surface;
a lid capable of opening and closing an opening on the upper surface of the main body,
The lid portion is connected to the upper edge portion of the rear plate of the main body portion and faces the upper surface of the main body portion, and the lid portion is connected to the front edge portion of the top plate and faces the front surface of the main body portion. A soft adhesive film storage box, comprising at least: a covering piece;
[13]
The soft adhesive film storage box according to [12], wherein a cutting portion is provided at the lower edge of the covering piece as a means for cutting the soft adhesive film pulled out from the core tube.

The soft adhesive film of the present invention is excellent in visibility and anti-glare property, and is excellent in sticking property and operability of a button or the like from the top of the sticking.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of an example of the flexible adhesive film of this invention.

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.

<Soft adhesive film>
The soft adhesive film of the present embodiment includes a base film containing a soft resin as a main component, and an adhesive layer formed on the surface of the base film,
The surface roughness (Sa value) of the base film is 10 to 15 μm,
The surface roughness (Sa value) of the adhesive layer is 16 to 30 μm,
The absolute value of the difference between the refractive index of the base film and the refractive index of the adhesive layer is 0.07 or less.

By having such characteristics, the soft adhesive film of the present embodiment is excellent in visibility and anti-glare properties, and has good sticking properties and operability of buttons and the like from the top of the sticking. Specifically, for example, the soft adhesive film of the present embodiment can be used by being attached to medical devices of various sizes and shapes. It can suppress glare even when illuminated by indoor lights, etc., and has excellent visibility of medical equipment. In addition, the soft adhesive film of the present embodiment can maintain anti-glare properties even if it is repeatedly wiped with a chemical cloth or the like after being attached to a medical device or the like, and is particularly attached to a monitor screen or has buttons. Suitable for attaching to equipment. In addition, a liquid crystal monitor is generally formed by a liquid crystal screen and an outer frame, and the liquid crystal screen and the outer frame are made of different materials, and there are many cases where there is a step at the boundary between the liquid crystal screen and the outer frame. The soft adhesive film of the present embodiment tends to adhere to both the liquid crystal screen and the outer frame while following such steps. Furthermore, the soft adhesive film of the present embodiment tends to be able to be folded and attached to the back side of the liquid crystal screen.

The soft adhesive film of this embodiment has a base film and an adhesive layer formed on the surface of the base film. Here, the "adhesive film" is a film containing an adhesive layer, specifically, for example, a film having adhesiveness as defined in JIS Z0109-1992, water, solvent, heat, etc. The film alone is heated at room temperature 15 to 25 ° C. (however, the adhesiveness is not limited to this temperature) for a short time (eg, 0.1 to 1.0 seconds), with a slight pressure (eg, 1 It is a film that can be temporarily adhered to other materials by simply applying ~50 kPa). Here, "temporarily adhered" means that it is in a state where it can be peeled off after being adhered, rather than being permanently adhered so that it cannot be peeled off after being adhered. It involves maintaining the adhesive state until it is physically removed. In addition, the above "adhesive film" can be applied to almost all materials (for example, wood products, metal, glass, various plastic materials, gypsum materials, tiles, etc.) etc.). The term "soft adhesive film" refers to the adhesive film described above, in which the base film contains a soft resin as a main component.

The soft adhesive film of the present embodiment preferably has a HAZE value of 15 to 30%. In addition, the soft adhesive film of the present embodiment preferably has a GLOSS value of 10 to 50% measured on the substrate film surface side. When the HAZE value and the GLOSS value are within the above ranges, the soft adhesive film of the present embodiment tends to be able to suppress glare due to, for example, illumination light while ensuring visibility. From the same point of view, the HAZE value is more preferably 15-25%, and the GLOSS value is more preferably 10-40%.

The method for controlling the HAZE value within the above range is not particularly limited as long as it is a method that can control the HAZE value of the soft adhesive film. There are a manufacturing method and a method for controlling the surface roughness (Sa value), which will be described later, and a method for controlling by an optimum combination of these is mentioned.

In addition, the method for controlling the GLOSS value within the above range is not particularly limited as long as it is a method capable of controlling the HAZE value of the soft adhesive film. There are a film manufacturing method, a method for optimizing the refractive index difference between the base film and the adhesive layer described later, and a method for controlling the surface roughness (Sa value) described later, and a method of controlling by an optimal combination thereof.

In the present embodiment, the HAZE value and GLOSS value of the soft adhesive film can be measured by the methods described in Examples below.

In the soft adhesive film of the present embodiment, the base film has a surface roughness (Sa value) of 10 to 15 μm, and the adhesive layer has a surface roughness (Sa value) of 16 to 30 μm. In the soft adhesive film of the present embodiment, when the surface roughness of the base film and the adhesive layer are within the above ranges, glare due to illumination light, for example, can be suppressed while ensuring visibility. In addition, when the surface roughness (Sa value) of the adhesive layer of the soft adhesive film of the present embodiment is within the above range, for example, when it is attached to a smooth part such as a monitor screen, air can easily escape, and the film can be cleaned cleanly. It becomes possible to stick it, and it tends to be excellent in sticking property. From a similar point of view, in the soft adhesive film of the present embodiment, the surface roughness (Sa value) of the base film is preferably 10 to 13 μm, and the surface roughness (Sa value) of the adhesive layer is preferably 16 to 25 μm. In the soft adhesive film of the present embodiment, when the surface roughness (Sa value) of the adhesive layer is 25 μm or less, the adhesive strength is good, so it is possible to suppress spontaneous peeling after being attached to the adherend. There is a tendency.

In addition, in this embodiment, the surface roughness (Sa value) of the base film and the adhesive layer can be measured by the method described in Examples below.

The method for controlling the surface roughness (Sa value) of the base film and the adhesive layer within the above range is not particularly limited. Examples include a method of laminating a base film on a layer and a method of directly embossing a soft adhesive film. Among these methods, a method of applying an adhesive layer to a release sheet and then laminating a substrate film on the adhesive layer is preferable. The surface roughness of the release sheet used at this time is preferably 5 to 13 μm, more preferably 7 to 13 μm, even more preferably 8 to 13 μm.

When the surface roughness of the release surface of the release sheet is within the above range, the surface roughness of the adhesive layer can be easily controlled within the above range. Further, by appropriately adjusting the thickness of the adhesive layer temporarily formed on the release surface, the surface roughness of the substrate film can be easily controlled within the above range. Here, the thickness of the adhesive layer temporarily formed on the release surface is preferably in the range of 50 to 250% of the surface roughness (Sa value) of the release sheet.

Also, the thickness of the release sheet is preferably 20 to 200 μm, more preferably 30 to 130 μm. When the thickness of the release sheet is 20 μm or more, the rigidity of the release sheet is improved, so that the soft adhesive film tends to be easily peeled off. On the other hand, when the thickness of the release sheet is 200 μm or less, the release sheet tends to be easily bent and peeled off when the soft adhesive film is peeled off. will also be beneficial.

(refractive index)
In the soft adhesive film of the present embodiment, the absolute value of the difference between the refractive index of the base film and the adhesive layer is 0.07 or less, preferably 0 or more and 0.07 or less. When the difference in refractive index is within the above range, reflection of light such as illumination entering the film at the interface between the base film and the adhesive layer can be suppressed, and glare can be suppressed. . From the same point of view, the absolute value of the difference between the refractive index of the base film and the adhesive layer is more preferably 0.06 or less, more preferably 0.05 or less. The method for controlling the absolute value of the difference between the refractive index of the base film and the adhesive layer within the above range is not particularly limited, but for example, the refractive index of each raw material resin of the base film and the adhesive layer is adjusted. The raw material resin for the base film and the raw material resin for the adhesive layer are appropriately adjusted so that the absolute value of the difference between the refractive index of the base film and the refractive index of the adhesive layer is within the above range. There is a method of selection.

In addition, in this embodiment, the difference in refractive index can be obtained by measuring the refractive indexes of the base film and the adhesive layer and calculating the difference.

In the soft adhesive film of the present embodiment, the surface roughness (Sa value) of the base film and the adhesive layer is within the above range, and the difference in refractive index between the base film and the adhesive layer is within the above range. Even if inexpensive materials with a high refractive index are used as materials for the base film and the adhesive layer, a sufficient effect of suppressing glare can be obtained. The refractive index of the material of the base film and the adhesive layer is preferably 1.60 or less, more preferably 1.55 or less.

In addition, in this embodiment, the refractive index of the base film and the adhesive layer can be measured by the method described in Examples below.

(2% strain elastic modulus)
In addition, the soft adhesive film of the present embodiment preferably has a 2% strain elastic modulus (tensile elastic modulus) in the machine direction (MD direction) and width direction (TD direction) of the film of 10 to 500 MPa. 300 MPa is more preferable, and 50 to 200 MPa is even more preferable. In the soft adhesive film of the present embodiment, when the 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) of the film is within the above range, push button operability tends to be improved, Also, when attaching to the liquid crystal screen and the outer frame of the liquid crystal monitor, there is a tendency that the adhesive can be attached while following the step between the liquid crystal screen and the outer frame.

The method for controlling the 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) of the film within the above range is not particularly limited, but for example, a base film made of a soft resin with a low elastic modulus A method using

In addition, in this embodiment, the 2% strain elastic modulus can be measured by the method described in Examples below.

(Base film)
The component constituting the base film used in this embodiment is mainly composed of a soft resin. Here, the soft resin is a resin having a tensile elastic modulus (2% strain elastic modulus) of 1000 MPa or less when the resin is formed into a film having a thickness of 40 μm. The tensile modulus is preferably 500 MPa or less, more preferably 200 MPa or less. The tensile modulus can be measured with reference to ASTM-D882 using a sample obtained by forming a resin into a film having a thickness of 40 μm. That is, a film having a thickness of 40 μm formed using a resin was cut into a sample having a width of 10 mm and a length of 100 mm, and the measurement was performed at a tensile speed of 5 mm / min. The tensile modulus can be calculated by dividing the load value at the time of pulling and elongation by 2% by the cross-sectional area of the sample (thickness (40 μm)×width (10 mm)) and converting it into a unit area (mm ² ).

If the main component of the base film is a soft resin, flexibility will be improved, so it will be easier to stick it along devices of various shapes and to operate buttons, etc. after attaching it to buttons and keytabs. Become.

Examples of flexible resins include, but are not limited to, polyolefin resins such as polyethylene and polypropylene, soft polyvinyl chloride resins, polyvinylidene chloride resins, ethylene-vinyl acetate copolymers, and polyurethane resins. . Among these, the soft resin is preferably a polyolefin-based resin, more preferably a polyethylene-based resin, from the viewpoint of cost and refractive index. 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.

(polyethylene resin)
In the flexible adhesive film of the present embodiment, the flexible resin is preferably a resin containing polyethylene-based resin as a main component.

Examples of polyethylene-based resins include, but are not particularly limited to, low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and the like. Among these, low-density polyethylene resins and linear low-density polyethylene resins are preferable as components constituting the base film, and it is more preferable to use low-density polyethylene resins as the main component. The soft adhesive film of the present embodiment uses a low-density polyethylene resin as a main component as a component constituting the base film, so that flexibility is further improved, so that it can be adhered along devices of various shapes. , buttons and keytabs tend to be easier to operate. In addition, the soft adhesive film of the present embodiment tends to be improved in tear resistance by using a low-density polyethylene resin as a main component as a component constituting the base film. Furthermore, it is superior in terms of cost. 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. In the present embodiment, the "main component" refers to a component of 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably, when the total amount of components is 100% by mass. is 90% by mass or more, particularly preferably 100% by mass.

The polyethylene resin preferably has a melt flow rate (MFR) at 190° C. and a load of 2.16 kg of 1 to 10 g/10 min, more preferably 1.5 to 8 g/10 min, and 1.8 to More preferably, it is 7 g/10 min.

The polyethylene resin preferably has a density of 915 to 930 kg/m ³ , more preferably 916 to 925 kg/m ³ , even more preferably 917 to 920 kg/m ³ .

The polyethylene resin preferably has a molecular weight distribution (Mw/Mn) of 10 to 25, more preferably 12 to 23, even more preferably 13 to 21.

A method for obtaining a polyethylene-based resin having a molecular weight distribution within the above range is not particularly limited, but includes, for example, a method of intentionally increasing branching of the resin to provide a peak shoulder on the high molecular weight side.

The polyethylene resin preferably has a melt tension at 190° C. of 30 to 120 mN, more preferably 35 to 115 mN, even more preferably 35 to 70 mN.

In the flexible adhesive film of the present embodiment, if the base film is a film made of a polyethylene-based resin whose MFR, density, molecular weight distribution, and melt tension are within the above ranges, the films are stiff when attached. It becomes less likely to get tangled, becomes moderately flexible, can easily conform to the shape of an adherend, has a tear strength that easily falls within a desired range, and can be easily processed into a film, so that it tends to be even easier to use. Polyethylene-based resins also have the advantage of being generally inexpensive and easy to obtain.
In addition, in this embodiment, the MFR, density, molecular weight distribution and melt tension of the polyolefin resin can be measured by the following methods.

(1) Measurement of melt flow rate (MFR) of polyolefin resin in base film (sample preparation method)
An aluminum plate with a thickness of 0.1 mm is placed on a smooth steel plate with a thickness of 5 mm, and a polyethylene terephthalate film (Lumirror manufactured by Toray Industries, Inc.) with a thickness of 50 μm is placed on the aluminum plate. A mold having a length of 200 mm, a width of 200 mm, and a thickness of 0.7 mm is placed on the mold, and 28 g of the base film (sample) is put into the mold. Then, a polyethylene terephthalate film similar to that described above, an aluminum plate similar to that described above, and an iron plate similar to that described above are further placed thereon.
This is placed in a compression molding machine (SFA-37 manufactured by Shindo Kinzoku Kogyo Co., Ltd.) whose temperature is adjusted to 170 ° C., preheated at 170 ° C. and 0.1 MPa for 180 seconds, and then air is removed for 5 seconds (10 MPa). Pressurization is performed at 170° C. and 15 MPa for 120 seconds.
After the pressurization is completed, the sample is taken out, and 5 seconds after taking it out, the sample is placed in a compression molding machine (manufactured by Shindo Kinzoku Kogyo Co., Ltd. SFA-37) whose temperature is adjusted to 25 ° C., 25 ° C., 10 MPa for 300 seconds. A press sheet is produced by cooling while pressurizing. The press sheet thus obtained is cut into a 5 mm square to obtain a base film press sheet cut product.
(MFR measurement method)
Using the base film press sheet cut-out product obtained above, the MFR of the polyolefin resin in the base film conforms to JIS K7210: 1999 (when the polyolefin resin is a polyethylene resin, temperature = 190 ° C., load = 2.16 kg). Note that the measurement is performed within 8 hours after the press sheet is produced.

(2) Method for measuring the density of polyolefin resin in the base film Using the base film press sheet cutout obtained in (1) above, the density of the polyolefin resin in the base film was measured according to JIS K7112:1999. The measurement is performed according to the density gradient tube method (23°C). Note that the measurement is performed within 8 hours after the press sheet is produced.

(3) Molecular weight distribution (Mw/Mn) measurement method of polyolefin resin in base film /Mn) is the molecular weight distribution. GPC measurement is performed under the following conditions. As a sample, the substrate film press sheet cut-out product obtained in (1) above is used. As a pretreatment, 8 mg of a sample is weighed, 8 mL of ortho-dichlorobenzene is added, and the sample is shaken and dissolved at 140° C. for 90 minutes. Molecular weight calibration is performed at 11 points (A-1000, A-2500, A-5000) in the range of Mw (Molecular weight) from 1,050 to 20,600,000 of Tosoh Corporation standard polystyrene (TSKgel standard polystyrene) , F-1, F-4, F-20, F-40, F-288, F-550, F-850, F-2000) and multiplying the Mw of each standard polystyrene by a factor of 0.43 The molecular weight is converted to polyolefin. A primary calibration straight line is created from a plot of elution time and polyolefin equivalent molecular weight to determine the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polyolefin resin in the substrate film.
(GPC measurement conditions)
Apparatus: GPC-IR manufactured by Polymer Char
Detector: IR5 manufactured by Polymer Char
Column: UT-807 (1 piece) manufactured by Showa Denko K.K. and GMHHR-H(S)HT (2 pieces) manufactured by Tosoh Corporation are connected in series and used Mobile phase: ortho-dichlorobenzene Column temperature: 140°C
Flow rate: 1.0 mL/min Sample concentration: 8 mg/8 mL

(4) Method for measuring the melt tension of the polyolefin resin in the base film Using the base film press sheet cutout obtained in (1) above, the melt tension of the polyolefin resin in the base film was measured as follows. Measure as follows. Using a capillograph, the melt tension (MT) is measured as the force on the pulley as the strand is pulled through the pulley. Specifically, using Capilograph 1D manufactured by Toyo Seiki Co., Ltd., using an orifice with a barrel diameter of 9.55 mm, an orifice diameter of 2.095 mm, a length of 7.98 mm, and an inflow angle of 90 degrees, the resin temperature was 190 ° C. in the base film. to measure the melt tension of the polyolefin resin. The piston descends at 6 mm/min and the take-up speed is 3 mm/min.

(polypropylene resin)
In the flexible adhesive film of the present embodiment, the flexible resin is preferably a resin containing a polypropylene-based resin as a main component.

Examples of polypropylene-based resins include, but are not particularly limited to, homopolypropylene (hPP), random polypropylene (rPP), syndiotactic polypropylene (sPP), and the like. Among these, it is more preferable to use random polypropylene as a main component as a component that constitutes the base film. The flexible adhesive film of the present embodiment tends to have improved flexibility and tear resistance by using random polypropylene as a main component as a component constituting the base film. Moreover, it is superior in terms of cost. 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.

The polypropylene resin preferably has a melt flow rate (MFR) at 230° C. and a load of 2.16 kg of 0.1 to 100 g/10 min, more preferably 0.2 to 80 g/10 min, and still more preferably 0.3 to 60 g/10 min, particularly preferably 0.5 to 40 g/10 min, most preferably 1.0 to 20 g/10 min. When the MFR of the polypropylene-based resin is 0.1 g/10 min or more, the extrusion processability tends to be good. On the other hand, when the MFR of the polypropylene-based resin is 100 g/10 min or less, the durability tends to be good. . Here, the MFR at 230°C is a value measured at 230°C under a load of 2.16 kg according to JISK7210. Specifically, it is a value measured by the same method as the method (1) above except for the temperature conditions.

The polypropylene resin preferably has a density of 870 to 940 kg/m ³ , more preferably 875 to 935 kg/m ³ , still more preferably 880 to 930 kg/m ³ , and 885 to 920 kg/m 3 . m ³ is particularly preferred, and 895-910 kg/m ³ is most preferred. If the density of the polypropylene resin is 870 kg/m ³ or more, it tends to be possible to maintain the rigidity of the film, and if the density of the polypropylene resin is 940 kg/m ³ or less, the film becomes transparent. It tends to be easier to maintain sex. Here, the density is a value measured according to JISK7112. Specifically, it is a value measured by the same method as the method (2) above.

The polypropylene resin preferably has a molecular weight distribution (Mw/Mn) of 1.5 to 20, more preferably 2.0 to 18, even more preferably 2.5 to 16. 0.8 to 14 are particularly preferred, and 3.2 to 10 are most preferred. If the molecular weight distribution of the polypropylene resin is 1.5 or more, the flow stability of the molten resin during extrusion tends to increase, and if the molecular weight distribution of the polypropylene resin is 20 or less, the discharge amount during extrusion is balanced. This reduces the load on the motor and enables stable continuous production.

The polypropylene resin preferably has a melt tension at 190° C. of 10 to 120 mN, more preferably 15 to 115 mN, even more preferably 20 to 70 mN. When the melt tension of the polypropylene-based resin at 190° C. is 10 mN or more, the melt elastic modulus of the propylene-based polymer is increased, so neck-in during film molding is reduced, and excellent film-forming processability is obtained. When the melt tension of the polypropylene-based resin at 190° C. is 120 mN or less, the film can be formed more stably, and a film with a more uniform thickness tends to be obtained.

In the flexible adhesive film of the present embodiment, if the base film is a film made of a propylene-based resin whose MFR, density, molecular weight distribution, and melt tension are within the ranges described above, the film will be stiff when attached. It becomes less likely to get tangled, becomes moderately flexible, can easily conform to the shape of an adherend, has a tear strength that easily falls within a desired range, and can be easily processed into a film, making it even easier to use. In addition, polypropylene-based resins also have the advantage of being generally inexpensive and easy to obtain.

(Additive in base film)
The base film used in the present embodiment contains, if necessary, known plasticizers, heat stabilizers, colorants, organic lubricants, inorganic lubricants, surfactants, electrifying agents, Other additives such as inhibitors, processing aids, antioxidants, light stabilizers, UV absorbers, antimicrobial agents, etc. may be included.

The base film used in the present embodiment may be a stretched oriented film or a non-(low) oriented film, but a non-(low) oriented film is preferred.

The thickness of the base film used in the present embodiment is preferably 10 to 80 μm, more preferably 20 to 60 μm, from the viewpoint of wet spreadability and operability and durability of personal computers and medical devices. More preferably, it is 25 to 50 μm.
In addition, in this embodiment, the thickness of the base film can be measured by the method described in Examples below.

<Adhesive layer>
The soft adhesive film of this embodiment includes an adhesive layer. In addition, the adhesive strength of the adhesive layer (180 degree peel strength measured with reference to JIS Z0237) is preferably 0.01 to 1.5 N/25 mm (1 to 150 cN/25 mm), and preferably 0.03 to It is more preferably 1.2 N/25 mm (3 to 120 cN/25 mm), even more preferably 0.05 to 1.0 N/25 mm (5 to 100 cN/25 mm). By including such an adhesive layer, the soft adhesive film of the present embodiment has a tendency to adhere firmly to medical equipment and the like and to be easily peeled off.

A method for controlling the adhesive strength of the adhesive layer within the above range is not particularly limited, but examples thereof include a method of adjusting the hardness of the adhesive, the thickness of the adhesive layer, and the degree of curing of the curing agent.
In this embodiment, the adhesive strength of the adhesive layer can be measured by the method described in Examples below.

The adhesive that forms the adhesive layer is not particularly limited, and examples thereof include urethane-based adhesives, acrylic-based adhesives, rubber-based adhesives, silicone-based adhesives, and ethylene/vinyl acetate adhesives. From the point of view of one of the uses of this embodiment, which is temporarily attached to a medical device or the like, and then peeled off and discarded from the viewpoint of cleanliness after being used for a certain period of time, it can be attached and removed by hand rather than strong adhesiveness. It is preferable that the adhesive has a certain level of adhesive strength and is excellent in releasability so as not to leave an adhesive residue on the surface to which it is adhered. From this point of view, among the adhesives, urethane-based adhesives, silicone-based adhesives, acrylic-based adhesives, and rubber-based adhesives are preferable, and urethane-based adhesives are particularly preferable.

Urethane-based adhesives are adhesives made of polyurethane obtained by condensation of compounds with an isocyanate group and a hydroxyl group. tend to be more sexual. 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-based adhesive is an adhesive made 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-releasing properties during application.

Acrylic pressure-sensitive adhesives are pressure-sensitive adhesives containing (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, tackifier 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.
A biomass raw material may be used as the raw material of the adhesive layer.

With the adhesive layer formed of the above-described adhesive, the soft adhesive film of the present embodiment, for example, when used as a cover for a medical device, adheres firmly to the medical device and can be easily removed. It tends to peel off. In addition, the film tends to be easy to handle without tangling.

In the soft adhesive film of the present embodiment, the thickness of the adhesive layer is 50 to 250% of the surface roughness (Sa value) of the release sheet from the viewpoint of controlling the surface roughness of the adhesive layer within a predetermined range. Preferably. Further, in the soft adhesive film of the present embodiment, the thickness of the adhesive layer is preferably 2.5 to 33 μm, more preferably 3 to 30 μm, from the viewpoint of adhesive strength of the adhesive layer, and 5 to 30 μm. It is more preferably 30 μm, and even more preferably 10 to 30 μm.

When the thickness of the adhesive layer is within the above range, the soft adhesive film of the present embodiment, for example, when used as a cover of a medical device, is firmly attached to the medical device and can be easily removed when removed. It tends to appear more. In addition, the film tends to be easier to handle without tangling.
In addition, in this embodiment, the thickness of the adhesive layer can be measured by the method described in Examples below.

Furthermore, the soft adhesive film of the present embodiment may have a printed layer or a primer layer between the base film and the adhesive layer.

<Release sheet>
The soft adhesive film of the present embodiment may be a release sheet-attached soft adhesive film in which the surface of the adhesive layer is covered with a release sheet. Specifically, for example, the adhesive layer side of the layer containing the base film and the adhesive layer, that is, as a soft adhesive film with a release sheet in which the adhesive layer is further coated with a release sheet to protect the adhesive layer surface good too. Although the release sheet is not particularly limited, for example, paper, PET sheet, or the like, which is treated with silicone to exhibit releasability, can be used. By covering the surface of the adhesive layer with the release sheet in this way, the surface of the adhesive layer can be protected until it is attached to the adherend.

One mode of the soft adhesive film of this embodiment is shown as a schematic diagram in FIG.
Specifically, the soft adhesive film of the present embodiment is represented by, for example, a soft adhesive film 1 as shown in FIG. It has a structure in which the adhesive layer 3 is laminated on one surface.

The thickness of the soft adhesive film of the present embodiment is preferably 20-200 μm, more preferably 30-190 μm, even more preferably 50-180 μm.

When the thickness of the soft adhesive film is at least the above lower limit, the rigidity of the soft adhesive film is improved, so the self-supporting property tends to be improved, and the film may break or twist when pasted. It tends to be suppressed and easier to stick. Moreover, when the thickness of the soft adhesive film is equal to or less than the upper limit, the cuttability of the soft adhesive film tends to be further improved.

<Method for producing soft adhesive film>
The method for producing a soft adhesive film of the present embodiment can form an adhesive layer on the surface of a base film containing a soft resin as a main component, and the surface roughness (Sa value) of the adhesive surface and the base film can be set to a predetermined value. There is no particular limitation as long as the method can be within the range and the absolute value of the difference between the refractive index of the base film and the adhesive layer can be within the predetermined range. As a specific example, for example, a release sheet having an appropriate surface roughness is coated with an adhesive with a comma coater or gravure coater, dried, laminated with a base film on the adhesive layer, wound, and wound at 40 ° C. for 2 days. is particularly simple and inexpensive. In addition, before applying the adhesive, a primer having an affinity between the adhesive layer and the base film may be applied in advance, or the base film may be subjected to corona treatment. In addition, back surface treatment of the substrate film may be performed in a step before or after the pressure-sensitive adhesive coating.

In particular, the method for producing a soft adhesive film of the present embodiment includes a step of temporarily forming an adhesive layer by applying an adhesive to the release surface of a release sheet, and laminating a base film on the adhesive layer. wherein the surface roughness (Sa value) of the release sheet is 5 to 13 μm, and the thickness of the adhesive layer temporarily formed on the release surface is equal to the surface roughness (Sa value) of the release sheet ) is preferably in the range of 50 to 250%. By such a method, there is a tendency that a soft adhesive film can be obtained in which the surface roughness (Sa value) of the adhesive surface and the base film is within a predetermined range.

In addition, the base film used in the present embodiment, for example, a process of melt extruding a mixture containing a soft resin from an annular die into a tubular shape, and a method of inflation molding at a temperature above the melting point while air cooling the extruded original film. can be produced as a non-(low) oriented film by

<Soft adhesive film roll>
The soft sticky film roll of the present embodiment may be a soft sticky film roll comprising a core tube and the soft sticky film wound around the core tube, or may be free of A soft adhesive film roll with a core, for example, a soft adhesive film roll wound in a so-called coreless manner, which is wound without a core tube, may be used.

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. Moreover, the diameter of the core tube is not limited, and can be, for example, 10 mm to 50 mm.

The soft adhesive film of this embodiment can be used not only as a roll as described above but also as a sheet.

<Soft adhesive film storage box>
The storage box for the soft adhesive film of the present embodiment is a box that stores the wound body of the soft adhesive film described above. By storing the above-described soft adhesive film roll in a box, the shape of the roll can be maintained and the required amount of soft adhesive film can be pulled out.

The soft adhesive film storage box of the present embodiment preferably has means for pulling out the soft adhesive film from the box. For example, a necessary amount of film can be pulled out by providing a take-out opening for pulling out the soft adhesive film roll and allowing the roll to rotate freely in the storage box.

The soft adhesive film storage box of this embodiment is
a main body having at least a front plate, a bottom plate, a rear plate and a side plate, and having an open upper surface;
a lid capable of opening and closing an opening on the upper surface of the main body,
The lid portion is connected to the upper edge portion of the rear plate of the main body portion and faces the upper surface of the main body portion, and the lid portion is connected to the front edge portion of the top plate and faces the front surface of the main body portion. It is preferable to have at least a cover piece.

Furthermore, the soft adhesive film storage box of this embodiment can be provided with a means for cutting the soft adhesive film pulled out from the core tube. This makes it possible to easily cut the required amount of soft adhesive film pulled out. More preferably, the soft adhesive film storage box of the present embodiment is provided with a cutting portion at the lower edge of the covering piece as a means for cutting the soft adhesive film pulled out from the core tube. The means for cutting the soft adhesive film is not particularly limited. For example, a slide cutter may be used in addition to a saw blade made of metal, paper, or plastic. Among them, a saw blade made of metal is preferable because it can exhibit stable cutting properties.

The saw blade is preferably slightly longer than the width of the soft adhesive film, and its overall shape is preferably a straight line, but it may be V-shaped or gently curved.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive various modifications or modifications within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. understood as a thing.

<Uses of the soft adhesive film>
The soft adhesive film of this embodiment can be used to protect medical equipment. Here, objects such as medical equipment include, for example, switches and operation panels of inspection equipment such as MRI and CT, examination tables, electronic chart wagons, stretchers, personal computers, PHS, etc., in medical institutions such as hospitals. Equipment used in medical institutions such as office copiers, instruments, fixtures, fixtures, office furniture, and handrails. In addition to medical institutions, for example, equipment such as cash registers in retail stores, weighing machines in backyards and food processing plants, filling machines, workbenches, mobile carts, construction material surfaces and electronic equipment on construction sites, construction machinery It can be used without limitation for applications other than medical institutions, such as operation panels.

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.

The measurement methods used in Examples and Comparative Examples were as follows.

(1-1) Surface Roughness of Base Film Using a laser microscope “OLS4000” (manufactured by Olympus Corporation), the surface roughness of the base film was measured according to the following procedure. The soft or hard adhesive films obtained in Examples and Comparative Examples were cut at arbitrary locations into pieces of about 5×5 mm square to obtain samples. The resulting sample was fixed on a sample fixing disk with the substrate film facing upward. Using a laser microscope (OLS4000, manufactured by Olympus), a range of about 2.5 mm square with a magnification of the objective lens of 5 times is observed with the operation mode of "XYZ high precision". got the image. This measurement result is subjected to noise removal (one-shot filter “flat surface” and “surface correction”) processing in the surface roughness measurement mode, and then the surface roughness of the entire measurement surface is measured. Sa (arithmetic mean height of surface) generally used for evaluation was calculated, and the surface roughness of the substrate film of each sample was evaluated.

(1-2) Surface Roughness of Adhesive Layer Using a laser microscope "OLS4000" (manufactured by Olympus Corporation), the surface roughness of the adhesive layer was measured according to the following procedure. The soft or hard adhesive films obtained in Examples and Comparative Examples were cut at arbitrary locations into pieces of about 5×5 mm square to obtain samples. The resulting sample was fixed on a sample fixing disk with the adhesive layer facing up. Using a laser microscope (OLS4000, manufactured by Olympus), a range of about 2.5 mm square with a magnification of the objective lens of 5 times is observed with the operation mode of "XYZ high precision". got the image. This measurement result is subjected to noise removal (one-shot filter “flat surface” and “surface correction”) processing in the surface roughness measurement mode, and then the surface roughness of the entire measurement surface is measured. The surface roughness of the adhesive layer of each sample was evaluated by calculating Sa (arithmetic average height of the surface) which is generally used for evaluation.

(2-1) Refractive index of base film The refractive index of the base film is measured in accordance with JISK7142 using an Abbe refractometer "KPR-30A" (manufactured by Shimadzu Corporation) in the following procedure. gone. The soft or hard adhesive films obtained in Examples and Comparative Examples were cut at arbitrary locations into pieces of about 5×5 mm square to obtain samples. The resulting sample was fixed with the base film side thereof in contact with a prism, and the refractive index of the base film was measured with an Abbe refractometer (manufactured by Shimadzu Corporation, KPR-30A).

(2-2) Refractive index of adhesive layer The refractive index of the adhesive layer was measured in accordance with JISK7142 using an Abbe refractometer "KPR-30A" (manufactured by Shimadzu Corporation) in the following procedure. . The soft or hard adhesive films obtained in Examples and Comparative Examples were cut at arbitrary locations into pieces of about 5×5 mm square to obtain samples. The adhesive layer side of the obtained sample was brought into contact with a prism to fix the sample, and the refractive index of the adhesive layer was measured with an Abbe refractometer (manufactured by Shimadzu Corporation, KPR-30A).

(2-3) The difference between the refractive index of the base film and the refractive index of the adhesive layer The “refractive index of the base film” and the “refractive index of the adhesive layer” are measured as described above, and the refractive index of the base film is calculated using the following formula. A difference between the refractive index and the refractive index of the adhesive layer was calculated.
Refractive index difference = | (refractive index of base film) - (refractive index of adhesive layer) |

(3) Adhesive strength of adhesive layer The adhesive strength of the adhesive layer was measured as follows with reference to JISZ0237. That is, the soft or hard adhesive films obtained in Examples and Comparative Examples were cut in the MD direction into strips having a width of 25 mm and a length of 300 mm to obtain samples. The surface of the adhesive layer of 150 mm, which is half the length of this sample, was adhered to a mirror-finished SUS304 plate having a length of 150 mm by reciprocating twice at 10 mm/sec using a 2 kg weight roller. Holding the 150 mm edge that was not attached to the SUS304 plate, the tape was folded back at 180 degrees so that the back surface of the tape overlapped, and the tape was peeled off from the SUS304 plate by 25 mm. One end of the peeled SUS304 plate was fixed to one chuck of the tensile tester, and the folded end of the sample was fixed to the other chuck. Tensile measurement was performed at a speed of 300 mm/min, and the average value of five peel strength measurements (however, the measured value for 25 mm immediately after measurement was ignored) was taken as the adhesive strength value. For the measurement, a small desktop tester "EZ-SX" manufactured by Shimadzu Corporation was used. The 180-degree peel strength thus obtained was taken as the adhesive strength of the adhesive layer.

(4-1) Thickness of the base film The base film obtained in Examples and Comparative Examples is cut using a microtome, and the cut surface is observed with an optical microscope (Keyence VHX-900). thickness was measured. This was further measured in the MD direction (unwinding direction) of the base film at intervals of 1 m, and finally the average value of 10 points was taken as the thickness of the base film.

(4-2) Thickness of adhesive layer Cut the soft or hard adhesive film obtained in Examples and Comparative Examples using a microtome, and observe the cut surface with an optical microscope (Keyence VHX-900) to adhere. The layer thickness was measured. Further, the thickness of the soft or hard adhesive film was measured in the MD direction (unwinding direction) at intervals of 1 m, and finally the average value of 10 points was taken as the thickness of the adhesive layer.

(5) HAZE Value of Soft or Hard Adhesive Film The HAZE values of the soft or hard adhesive films obtained in Examples and Comparative Examples were measured according to JISK7136. Specifically, in an environment with a temperature of 23 ° C. and a relative humidity of 50%, the diffuse transmittance and total light transmittance of the soft or hard adhesive film are measured, and the HAZE of the soft or hard adhesive film is calculated by the following formula. value was calculated. The average value of five measurements was taken as the HAZE value of the soft or hard adhesive film. A haze meter NDH8000 manufactured by Nippon Denshoku Industries Co., Ltd. was used for the measurement.
HAZE (%) = diffuse transmittance/total light transmittance x 100

(6) GLOSS Value of Base Film Surface The GLOSS value of the base film surface of the soft or hard adhesive films obtained in Examples and Comparative Examples was measured according to JISZ8741. Specifically, in an environment with a temperature of 23 ° C. and a relative humidity of 50%, the base film of the soft or hard adhesive film obtained in the examples and comparative examples is MD or Set so that the TD direction is parallel, measure each at an incident angle of 45 degrees with respect to the base film surface, measure 5 times each in the MD and TD directions, and calculate the average value for each. The higher numerical value was taken as the GLOSS value of the base film surface of the soft or hard adhesive film. A gloss meter VG7000 manufactured by Nippon Denshoku Industries Co., Ltd. was used for the measurement.

(7) Glare prevention properties The soft or hard adhesive films obtained in Examples and Comparative Examples were directly pasted on the screen of a desktop computer monitor (DELL flat panel monitor), and the screen was displayed by turning on the power. Visually check whether characters on the screen can be recognized when the monitor angle is adjusted so that the fluorescent light installed on the room ceiling is reflected directly on the screen, and the glare prevention of the soft or hard adhesive film according to the following evaluation criteria. evaluated the sex.
(Evaluation criteria)
A: Characters on the screen could be recognized without any problem.
Δ: The characters on the screen were sometimes unrecognizable due to the reflected light of the fluorescent lamp depending on the viewing angle.
x: The characters on the screen were hardly recognizable due to the reflected light of the fluorescent lamp even when the viewing angle was changed.

(8) Visibility The soft or hard adhesive films obtained in the examples and comparative examples are directly attached to the screen of a monitor for desktop personal computers (flat panel monitor manufactured by DELL), the power is turned on to display the screen, The visibility of the soft or hard adhesive film was evaluated according to the following evaluation criteria by visually observing whether or not characters on the screen could be recognized at a position where light from a fluorescent lamp or the like was not directly reflected on the screen. In addition, 50 characters were randomly typed with Mincho font, font size 8, and font color black, and the distance between the screen and the eyes was 50 to 60 cm. Evaluation was made on 10 people with visual acuity of 0.3 or more (including corrected visual acuity by spectacles, contact lenses, etc.).
(Evaluation criteria)
Good: All 10 people could recognize the characters on the screen without any problem.
Δ: 8 to 9 persons could recognize all characters on the screen.
x: Seven or less people could recognize all the characters on the screen.

(9) Adherability The soft or hard adhesive films obtained in Examples and Comparative Examples were cut into 20 cm squares, and one side of the soft or hard adhesive film was attached to a glass plate (25 cm square). After holding the film while pulling both ends with the other hand to remove wrinkles from the film, the film was pressed against the glass plate with fingers to remove air, and the film was gradually adhered. Among the elliptical bubbles generated between the film and the glass plate, those with a short diameter of 3 mm or more were counted and evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: The number of air bubbles between the film and the glass plate was 0 to 5.
Δ: The number of air bubbles between the film and the glass plate was 6-10.
x: The number of air bubbles between the film and the glass plate was 11 or more.

(10) Push button operability The soft or hard adhesive films obtained in Examples and Comparative Examples were attached to a keyboard, and the character input performance was evaluated when Japanese sentences were typed for 10 minutes, and the following evaluations were performed. Judged according to the standard. The sensory evaluation was conducted by 50 or more men and women between the ages of 18 and 60, and the evaluation was based on the ratio of the number of people who felt dissatisfaction due to non-input or erroneous input.
◯: The percentage of people who felt dissatisfied was less than 10%.
△: The ratio of the number of people who felt dissatisfied was 10% or more and less than 30%.
x: The ratio of the number of people who felt dissatisfied was 30% or more.

(11) 2% strain elastic modulus (tensile elastic modulus) in machine direction (MD direction) and width direction (TD direction) of soft or hard adhesive film
The 2% strain modulus of the film in machine direction (MD direction) and transverse direction (TD direction) was measured according to ASTM-D882. That is, the soft or hard adhesive films obtained in Examples and Comparative Examples were cut into 10 mm wide and 100 mm long samples in the MD and TD directions, respectively, and measured at a tensile speed of 5 mm/min. . A tangential line is drawn on the resulting stress-strain graph, and the load value at 2% elongation is divided by the cross-sectional area (thickness x width) of the sample to calculate the value converted to the unit area (mm ² ), and 5 times. was taken as the 2% strain elastic modulus of the soft or hard adhesive film. As a measuring device, a compact desktop tester "EZ-SX" manufactured by Shimadzu Corporation was used.

Raw materials used in Examples and Comparative Examples were as follows.

(low density polyethylene resin)
LDPE1: Suntec LD "L1850A" manufactured by Asahi Kasei Corporation, tensile modulus of elasticity 150 MPa
LDPE2: Suntech LD "M1820" manufactured by Asahi Kasei Corporation, tensile modulus of elasticity 160 MPa
LDPE3: Suntech LD "L2340" manufactured by Asahi Kasei Corporation, tensile modulus of elasticity 230 MPa
Here, the tensile modulus of each low-density polyethylene resin is obtained by measuring with reference to ASTM-D882 using a sample obtained by forming each low-density polyethylene resin into a film having a thickness of 40 μm. and That is, a film having a thickness of 40 μm formed using each low-density polyethylene resin was cut into a sample having a width of 10 mm and a length of 100 mm, and the measurement was performed at a tensile speed of 5 mm / min. A tangential line was drawn on the graph, and the load value at 2% elongation was divided by the cross-sectional area of the sample (thickness (40 μm)×width (10 mm)) and converted into a unit area (mm ² ) to calculate the tensile modulus. . As a measuring device, a compact desktop tester "EZ-SX" manufactured by Shimadzu Corporation was used.

(Base film)
PVdC: "Saran Film 635G" manufactured by Asahi Kasei Corporation (main components: polyvinylidene chloride (PVdC), polyvinyl chloride (PVC))
PS: "OPS film GM20 μm" manufactured by Asahi Kasei Corporation (main component: polystyrene)
PET2: "S-38 (LS)" manufactured by Unitika Ltd. (main component: polyethylene terephthalate)

(Release sheet)
Release paper 1: Oji F-Tex Co., Ltd. “74EPS” (thickness: 110 μm, release surface roughness: 8 μm)
Release paper 2: “Pure White 40” manufactured by Goyo Shiko Co., Ltd. (thickness: 60 μm, surface roughness of release surface: 11 μm)
Release paper 3: "SS45BOH" manufactured by Shinomura Chemical Industry Co., Ltd. (thickness: 70 µm, release surface roughness: 10 µm)
Release paper 4: Oji F-Tex Co., Ltd. "N-72GS (M)" (thickness: 70 μm, release surface roughness: 8 μm)
Release paper 5: "EN78P (N67)" manufactured by Lintec Corporation (thickness: 120 μm, surface roughness of release surface: 7 μm)
Release paper 6: "SSP-80FOM (C)" manufactured by Shinomura Chemical Industry Co., Ltd. (thickness: 80 μm, release surface roughness: 7 μm)
Release paper 7: "SB7P (N7)" manufactured by Lintec Corporation (thickness: 120 µm, release surface roughness: 14 µm)
Release paper 8: "RHC64B" manufactured by San A Kaken Co., Ltd. (thickness: 108 μm, surface roughness of release surface: 14 μm)
PET1: Oji F-Tex Co., Ltd. “38RL-07E” (thickness: 38 μm, release surface roughness: 1 μm)

[Example 1]
[Production of base film]
A base film (LDPE film, thickness: 25 μm) containing a low-density polyethylene resin (hereinafter also referred to as “LDPE”) as a main component was produced as follows.
A masterbatch of oleic acid amide (LDPE: oleic acid amide = 97:3) is added to 100 parts by mass of low-density polyethylene (Suntech LD "L1850A" manufactured by Asahi Kasei Corporation, denoted as "LDPE1" in Table 1). 1 part by mass was added (substantial concentration = 300 ppm) and mixed in a blender for 10 minutes. The resulting mixture is extruded with a melt extruder to form a melt bubble at a tubular die temperature of 140° C., and while being air-cooled with cold air, is inflated 40 times in the machine direction (MD) and 1.8 times in the width direction (TD). Molding was performed to obtain a tubular film. The obtained tubular film was folded with a pinch roll, and both outer surfaces were treated with corona to adjust to 42 to 44 dynes to prepare a flat long film. After that, it was separated into single films using a slitter to obtain a film having a thickness of 25 μm. The properties of the obtained film (base film) were measured by the above methods. Table 1 shows the measurement results.

[Production of soft adhesive film roll]
A release sheet (“74EPS” manufactured by Oji F-Tex Co., Ltd., denoted as “release paper 1” in Table 1), a urethane-based adhesive urethane 1 (main agent: Toyochem Co., Ltd. “Cyabine SH-101 (100 parts by mass)”, curing agent: “T501B (5 parts by mass)” manufactured by Toyochem Co., Ltd.) with a thickness of 20 μm (250% of the surface roughness (8 μm) of the release sheet (release paper 1)) using a comma coater. An adhesive layer was formed by coating, and the corona-treated surface of the base film produced above was laminated on the adhesive layer and wound up to obtain a raw soft adhesive film. Here, the surface roughness of the release sheet is set to a predetermined range, the ratio of the thickness of the adhesive layer to the surface roughness of the release sheet is adjusted to a predetermined range, and the base film is laminated on the adhesive layer. The surface roughness (Sa value) of the base film and the adhesive layer was controlled within a predetermined range. The raw soft adhesive film thus obtained was aged at 40° C. for 24 hours, slit to a width of 220 mm, and then wound on a paper tube having an outer diameter of 40 mm for 10 m to produce a roll of soft adhesive film. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 1.

[Examples 2 to 7]
A soft adhesive film roll was produced in the same manner as in Example 1, except that the type of low-density polyethylene resin and release sheet, and the thickness of the base film were changed as shown in Table 1. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 1.

[Comparative Example 1]
The release sheet was changed to PET (silicone-treated polyethylene terephthalate (PET) film (manufactured by Oji F-Tex Co., Ltd. 38RL-07E), denoted as "PET1" in Table 2-1), and the base film was a PVdC film ( A soft adhesive film roll was produced in the same manner as in Example 1, except that Saran Film 635G manufactured by Asahi Kasei Corp., thickness: 21 μm, indicated as “PVdC” in Table 2-1) was used. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-1. The soft adhesive film roll thus obtained had poor glare-preventing properties, and had a very large amount of bubble residue when applied to glass, resulting in poor application properties.

[Comparative Examples 2 to 4]
A soft adhesive film roll was produced in the same manner as in Comparative Example 1, except that the release sheet was changed as shown in Table 2-1. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-1. The soft adhesive film roll thus obtained had poor glare-preventing properties, and had a very large amount of bubble residue when applied to glass, resulting in poor application properties.

[Comparative Example 5]
A soft adhesive film roll was produced in the same manner as in Comparative Example 1, except that the release sheet was changed as shown in Table 2-1. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-1. The resulting soft adhesive film roll had poor anti-glare properties.

[Comparative Example 6]
A soft adhesive film roll was produced in the same manner as in Comparative Example 1, except that the release sheet was changed as shown in Table 2-1. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-1. The resulting soft adhesive film roll was excellent in stickability to glass, but poor in glare prevention.

[Comparative Examples 7-8]
A soft adhesive film roll was produced in the same manner as in Example 4, except that the release sheet was changed as shown in Table 2-2. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-2. The resulting soft adhesive film roll had poor anti-glare properties and poor adhesion to glass.

[Comparative Example 9]
A soft adhesive film roll was produced in the same manner as in Example 5, except that the release sheet was changed as shown in Table 2-2. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-2. The resulting soft adhesive film roll had good anti-glare properties, but poor visibility.

[Comparative Example 10]
A soft adhesive film roll was produced in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Table 2-2. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-2. The resulting soft adhesive film roll had poor anti-glare properties.

[Comparative Example 11]
A soft adhesive film roll was produced in the same manner as in Example 4, except that the thickness of the adhesive layer was changed as shown in Table 2-2. The resulting soft tacky film roll was aged at 28°C for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-2. The resulting soft adhesive film roll had poor anti-glare properties.

[Comparative Examples 12-13]
Hard adhesive in the same manner as in Example 2 except that the type of the base film was changed to a hard resin (PS, PET2) as shown in Table 2-2 and the thickness of the base film was changed as shown in Table 2-2. A flexible film roll was produced. The resulting hard sticky film roll was aged at 28° C. for 1 month and then measured for properties as described above. The measurement results are shown in Table 2-2. The resulting hard adhesive film roll was poor in glare prevention and push button operability.

1: soft adhesive film, 2: base film, 3: adhesive layer

Claims (13)

A base film containing a soft resin as a main component, and an adhesive layer formed on the surface of the base film,
The surface roughness (Sa value) of the base film is 10 to 15 μm,
The surface roughness (Sa value) of the adhesive layer is 16 to 30 μm,
A soft adhesive film, wherein the absolute value of the difference between the refractive index of the base film and the refractive index of the adhesive layer is 0.07 or less. 2. The soft adhesive film according to claim 1, wherein the 2% strain elastic modulus in the machine direction (MD direction) and width direction (TD direction) of the soft adhesive film is 10 to 500 MPa. The flexible adhesive film according to claim 1 or 2, wherein the flexible resin is a resin containing a polyethylene-based resin as a main component. The flexible adhesive film according to claim 1 or 2, wherein the flexible resin is a resin containing a polypropylene-based resin as a main component. The soft adhesive film according to any one of claims 1 to 4, wherein the base film has a thickness of 10 to 80 µm. The soft adhesive film according to any one of claims 1 to 5, wherein the adhesive layer contains a urethane-based adhesive. The flexible adhesive film according to any one of claims 1-6, having a HAZE value of 15-30%. The soft adhesive film according to any one of claims 1 to 7, wherein the GLOSS value measured on the surface side of the base film is 10 to 50%. The soft adhesive film according to any one of claims 1 to 8, wherein the surface of said adhesive layer is covered with a release sheet. A method for producing a soft adhesive film according to any one of claims 1 to 9,
a step of temporarily forming an adhesive layer by applying an adhesive to the release surface of the release sheet;
and laminating a base film on the adhesive layer,
The surface roughness (Sa value) of the release sheet is 5 to 13 μm, and the thickness of the adhesive layer temporarily formed on the release surface is 50 to 250% of the surface roughness (Sa value) of the release sheet. A method for producing a flexible adhesive film, which ranges from A soft adhesive film roll comprising a core tube and the soft adhesive film according to any one of claims 1 to 9 wound around the core tube. A box containing the soft adhesive film roll according to claim 11,
a main body having at least a front plate, a bottom plate, a rear plate and a side plate, and having an open upper surface;
a lid capable of opening and closing an opening on the upper surface of the main body,
The lid portion is connected to the upper edge portion of the rear plate of the main body portion and faces the upper surface of the main body portion, and the lid portion is connected to the front edge portion of the top plate and faces the front surface of the main body portion. A soft adhesive film storage box, comprising at least: a covering piece; 13. The soft adhesive film storage box according to claim 12, wherein a cutting portion is provided at the lower edge of said covering piece as means for cutting the soft adhesive film pulled out from the core tube.

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