JP2018172473A - Adhesive film for display protection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive film for display protection that suitably protects a display and satisfactorily prevents electrification at the time of peeling from the display.SOLUTION: An adhesive film for display protection has a base material 1, an adhesive layer 2 provided on one side of the base material 1, and an antistatic layer 3 that is provided on the other side of the base material 1 and is composed of a material containing PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrene sulfonate)).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive film for display protection.

  A surface protective film for protecting the surface of a display is widely used for smartphones and tablets. As this surface protective film, a re-peelable type surface protective film that protects the surface of the display and is peeled off from the display when the surface protection is no longer necessary (see, for example, Patent Document 1). .

  When such a surface protective film is peeled off, static electricity may be generated. When static electricity is generated in this way, dust or the like may adhere to the surface of the display.

  In order to prevent static electricity, it is conceivable that the surface of the surface protective film is subjected to an antistatic treatment. However, when the surface is wiped off with a sterilizing sheet containing alcohol, the antistatic property may be lowered.

JP 2006-18295 A

  The objective of this invention is providing the adhesive film for a display protection which can protect a to-be-adhered body suitably and is excellent in the prevention property of the charge at the time of peeling from an to-be-adhered body.

Such an object is achieved by the present invention described in the following (1) to (6).
(1) A base material, an adhesive layer provided on one surface side of the base material, and provided on the other surface side of the base material, PEDOT: PSS (poly (3,4-ethylenedioxythiophene) ): An antistatic layer made of a material containing poly (4-styrenesulfonate)), and a display-protective pressure-sensitive adhesive film.

  (2) The display-protective adhesive film according to (1), wherein the antistatic layer is made of a material containing a polyester having a hydroxyl group.

  (3) The adhesive film for display protection according to the above (1) or (2), wherein the visible light transmittance is 80% or more.

(4) The antistatic layer includes a binder resin and the PEDOT: PSS,
The content of the PEDOT: PSS in the antistatic layer is 0.5 to 50 parts by mass with respect to 100 parts by mass of the binder resin according to any one of (1) to (3). Adhesive film for display protection.

  (5) The said adhesive layer is a display protective adhesive film in any one of said (1) thru | or (4) containing a urethane type adhesive or an acrylic adhesive.

  (6) The display-protective adhesive film according to any one of (1) to (5), wherein the antistatic layer is made of a material crosslinked with a methylolmelamine-based crosslinking agent.

  ADVANTAGE OF THE INVENTION According to this invention, a to-be-adhered body can be protected suitably and the adhesive film for a display protection which is excellent in the prevention property of the charge at the time of peeling from an to-be-adhered body can be provided.

It is a typical longitudinal section showing a 1st embodiment of a pressure-sensitive adhesive film for display protection of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.
[Display protective adhesive film]
The display-protective pressure-sensitive adhesive film 10 of the present invention is used by being attached to the surface of a display. As shown in FIG. 1, the display protective adhesive film 10 includes a base material 1, an adhesive layer 2 provided on one surface side (lower side in the figure) of the base material 1, and the other of the base material 1. An antistatic layer 3 made of a material containing PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate)) Is provided.

  By sticking such a display-protective adhesive film 10 to the surface of the display, the display can be suitably protected. Furthermore, when the antistatic layer 3 contains PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate)), the conductivity of the pressure-sensitive adhesive film 10 for display protection is effective. Can be enhanced. Therefore, it is possible to prevent the display from being charged by static electricity generated when the display protective adhesive film 10 is peeled off from the display. Furthermore, when the display-protective adhesive film 10 is charged, foreign matter (for example, dust) is attracted to the display-protective adhesive film 10 to prevent the foreign matter from adhering to the surface of the display.

  In addition, “display” in this specification refers to a screen of a display device such as an organic EL, a liquid crystal panel, and an LED.

  Further, in this specification, “visible light” refers to light having a wavelength of about 380 nm to 780 nm. The visible light transmittance can be measured by the total light transmittance described later.

<Base material>
The substrate 1 is a part having a function of supporting the pressure-sensitive adhesive layer 2 and the antistatic layer 3.

  Regardless of whether the substrate 1 is colored or colorless, the substrate 1 preferably has visible light permeability. Thereby, the surface of the display can be visually recognized through the substrate 1.

  Examples of the constituent material of the substrate 1 include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate; and resin materials such as polyethylene, polypropylene, and polyolefin.

  Moreover, the base material 1 may contain components other than those described above. Such components include, for example, colorants such as dyes and pigments, antioxidants such as anilides and phenols, UV absorbers such as benzophenones and benzotriazoles, light stabilizers, fillers, and heat stabilizers. And lubricants.

The substrate 1 may be a porous body or a laminate including a plurality of layers.
Moreover, the base material 1 may be comprised with the inclination material from which a composition changes in gradient in the thickness direction, for example.

  Moreover, the base material 1 may be subjected to a surface treatment for improving the adhesiveness with the pressure-sensitive adhesive layer 2.

  Examples of such surface treatment include acrylic, polyurethane, and polyester primer coats and corona treatment.

  Although the thickness of the base material 1 is not specifically limited, It is preferable that they are 10 micrometers or more and 300 micrometers or less, and it is more preferable that they are 20 micrometers or more and 150 micrometers or less.

  Such a substrate 1 preferably has a total light transmittance of 30% or more and 99% or less, more preferably 50% or more and 98% or less, measured in accordance with JIS K 7361-1. Thereby, the display can be easily visually recognized through the base material 1. When the total light transmittance is too low, it becomes difficult to visually recognize the display through the substrate 1.

<Adhesive layer>
The pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composition mainly composed of a pressure-sensitive adhesive.
Examples of the pressure sensitive adhesive include urethane pressure sensitive adhesive and acrylic pressure sensitive adhesive.

  Examples of the urethane resin include polyether polyurethane and polyester polyurethane.

  These urethane resins are usually produced by a polyaddition reaction of a polyol such as polyether polyol or polyester polyol and a diisocyanate.

The diisocyanate is not particularly limited, aromatic isocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate, aliphatic isocyanates such as hexamethylene diisocyanate, araliphatic isocyanates such as xylylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, etc. Is mentioned.
These can be used individually by 1 type or in combination of 2 or more types.

  Further, the urethane resin may have a three-dimensional crosslinked structure obtained by reacting a urethane prepolymer having a hydroxyl group with a diisocyanate crosslinking agent.

  In addition, when the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive, the main monomer component that provides adhesiveness, the comonomer component that provides adhesiveness and cohesive force, and the functional group-containing monomer component for improving the crosslinking point and adhesiveness are mainly used. It can be composed of a polymer or a copolymer.

  In the following, for example, “(meth) acrylic acid” indicates both “acrylic acid” and “methacrylic acid”, and the same applies to other similar terms.

  Examples of the main monomer component include (meth) acrylic acid alkyl esters such as ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate. Etc.

  Examples of the comonomer component include methyl (meth) acrylate, vinyl acetate, styrene, acrylonitrile and the like.

  Examples of the functional group-containing monomer component include monomers having a carboxy group such as (meth) acrylic acid, maleic acid, itaconic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4- Monomers having a hydroxy group such as hydroxybutyl (meth) acrylate and N-methylol (meth) acrylamide, (meth) acrylamide, glycidyl (meth) acrylate and the like can be mentioned.

  The content of the functional group-containing monomer component is preferably 0.1% by mass or more, more preferably 0.5% by mass with respect to all the structural units (100% by mass) of the acrylic polymer constituting the acrylic pressure-sensitive adhesive. % Or more. Further, the content of the functional group-containing monomer component is preferably 10% by mass or less, more preferably 5% by mass or less, with respect to all the structural units (100% by mass) of the acrylic polymer constituting the acrylic pressure-sensitive adhesive. is there.

  By including these components, the adhesive force and cohesive force of the pressure-sensitive adhesive composition are improved. Moreover, since such an acrylic adhesive normally does not have an unsaturated bond in a molecule | numerator, the improvement with respect to light or oxygen can be aimed at. Furthermore, a pressure-sensitive adhesive composition having quality and characteristics according to the application can be obtained by appropriately selecting the type and molecular weight of the monomer.

  As such a pressure-sensitive adhesive composition, any of a crosslinked type that undergoes crosslinking treatment and a non-crosslinked type that does not undergo crosslinking treatment may be used, but a crosslinked type is more preferred. When the cross-linked type is used, the pressure-sensitive adhesive layer 2 having better cohesive force can be formed.

  Examples of the crosslinking agent used in the crosslinking adhesive composition include epoxy compounds, isocyanate compounds, metal chelate compounds, metal alkoxides, metal salts, amine compounds, hydrazine compounds, and aldehyde compounds.

  Moreover, in the adhesive composition used for this invention, various additives, such as a plasticizer, a tackifier, and a stabilizer, may be contained as needed.

  The average thickness of the pressure-sensitive adhesive layer 2 is not particularly limited, but is preferably 1 μm or more and 100 μm or less, and more preferably 5 μm or more and 50 μm or less. Thereby, the adhesive force of the adhesive film 10 for display protection with respect to a display is fully securable.

<Antistatic layer>
The antistatic layer 3 is disposed on the surface of the substrate 1 opposite to the pressure-sensitive adhesive layer 2. The antistatic layer 3 is obtained by applying a coating solution containing an antistatic agent and a binder resin on the surface of the substrate 1 opposite to the pressure-sensitive adhesive layer 2 and drying it.

  In the present invention, PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate)) is used as the antistatic agent. PEDOT: PSS is a compound represented by the following chemical formula (1).

  By including such PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate)), it is possible to effectively increase the conductivity of the adhesive film 10 for display protection. it can. Therefore, it is possible to prevent the display from being charged by static electricity generated when the display protective adhesive film 10 is peeled off from the display. Furthermore, when the display-protective adhesive film 10 is charged, foreign matter (for example, dust) is attracted to the display-protective adhesive film 10 to prevent the foreign matter from adhering to the surface of the display.

  In addition, the content of PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate)) in the antistatic layer 3 is 0.5 mass relative to 100 parts by mass of the binder resin. It is preferably no less than 50 parts by mass and no greater than 1 part by mass and no greater than 30 parts by mass. Thereby, while being able to exhibit the effect mentioned above reliably, it can prevent that the adhesiveness with respect to the base material 1 of the antistatic layer 3 falls.

  Examples of the binder resin include polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, and polyvinyl alcohol. These binder resins may have a skeleton structure having a composite structure by copolymerization or the like. Examples of the binder resin having a composite structure include acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, and vinyl resin graft polyurethane.

  Here, with the display protective adhesive film 10 adhered to the display, the surface of the display protective adhesive film 10 (antistatic layer 3) was soaked with alcohol for the purpose of wiping off fingerprints and sebum adhering to the display. May be wiped with a cloth. At this time, the antistatic agent may be deteriorated by alcohol. Therefore, it is preferable to use polyester having a hydroxyl group as the binder resin. Thereby, when a crosslinking agent as will be described later is added, a relatively hard film can be formed, and the alcohol resistance of the antistatic layer 3 can be enhanced.

  In order to improve the blocking property of the antistatic layer 3, the antistatic layer 3 may contain a polyolefin resin and / or a fluorine resin in addition to the antistatic agent.

  The antistatic layer 3 may contain a crosslinking reactive compound. A crosslinking-reactive compound is obtained by including a crosslinking agent in a coating solution containing an antistatic agent and causing a crosslinking reaction with a functional group of the compound contained in the coating solution. By including a crosslinking agent in the coating solution, the blocking property, water resistance, solvent resistance, and mechanical strength of the antistatic layer 3 are improved.

  Examples of the crosslinking agent include melamine-based crosslinking agents, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, and the like, and methylol melamine-based crosslinking agents are particularly preferable. Thereby, it can react with the polyester having a hydroxyl group as a binder resin to form a relatively hard film, and the alcohol resistance of the antistatic layer 3 can be enhanced.

  The melamine-based crosslinking agent may be methoxymethylated melamine or butoxymethylated melamine, which is an alkylol or alkoxyalkylolated melamine compound, and is obtained by co-condensing urea or the like with a part of melamine. It may be.

  The antistatic layer 3 may contain at least one of additives such as an antifoaming agent, a coating property improving agent, a thickening agent, an organic lubricant, organic particles, and inorganic particles, if necessary.

  The thickness of the antistatic layer 3 is a thickness after drying, and is preferably from 0.003 μm to 1.5 μm, and more preferably from 0.005 to 0.5 μm. When the thickness of the antistatic layer 3 is 0.003 μm or more, sufficient antistatic performance can be obtained. Further, when the thickness of the antistatic layer 3 is 1.5 μm or less, blocking can be prevented.

  The antistatic layer 3 preferably has a total light transmittance of 80% or more and 99% or less, more preferably 85% or more and 98% or less, measured in accordance with JIS K 7361-1. Thereby, the surface of the display can be easily visually recognized through the antistatic layer 3. When the total light transmittance is too low, it becomes difficult to visually recognize the surface of the display through the antistatic layer 3.

  The display protective adhesive film 10 as a whole preferably has a total light transmittance of 50% or more and 99% or less, measured in accordance with JIS K 7361-1, and is 80% or more and 98% or less. Is more preferable. Thereby, the surface of the display can be easily visually recognized through the antistatic layer 3. When the total light transmittance is too low, it becomes difficult to visually recognize the surface of the display through the antistatic layer 3.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to these.

  For example, the display-protective pressure-sensitive adhesive film may have at least one intermediate layer between the base material and the pressure-sensitive adhesive layer or between the base material and the antistatic layer. For example, the display-protective pressure-sensitive adhesive film may have an adhesion enhancing layer (such as a primer layer).

  Hereinafter, the present invention will be described in more detail with reference to specific examples, but the present invention is not limited to these examples. In the following description, the treatment that does not particularly indicate the temperature condition is performed at room temperature (23 ° C.) and a relative humidity of 50%. Moreover, what does not show temperature conditions in particular also about various measurement conditions is a numerical value in room temperature (23 degreeC) and 50% of relative humidity.

[1] Production of display protective adhesive film (Example 1)
Urethane prepolymer having a hydroxyl group: 100 parts by mass (solid content), isocyanate cross-linking agent (“Coronate HL” manufactured by Tosoh Corporation): 10 parts by mass (solid content), MEK is added to a solid content of 50% by mass. It diluted so that it might become, and the liquid adhesive composition was prepared.

  Next, the pressure-sensitive adhesive composition prepared as described above was subjected to a knife coater on the surface on which the silicone-treated polyester film having a thickness of 38 μm, which was a release liner, was peeled, so that the thickness of the pressure-sensitive adhesive layer after drying was reduced. It apply | coated so that it might be set to 20 micrometers, Then, it dried at 100 degreeC for 1 minute, and formed the adhesive layer.

  A liquid antistatic composition was obtained by mixing 100 parts by mass of a hydroxyl group-containing polyester resin (solid content), 6 parts by mass of PEDOT: PSS (solid content), and 20 parts by mass of a methylolmelamine-based crosslinking agent (solid content). .

  Then, the antistatic composition was applied to one surface of a 50 μm thick polyethylene terephthalate film so that the thickness after drying was 20 nm, and dried at 120 ° C. for 1 minute to form an antistatic layer. Formed.

  And the adhesive film for display protection was obtained by bonding an adhesive layer to the surface on the opposite side to the antistatic layer of a polyethylene terephthalate film.

(Examples 2 to 4)
Except having changed the structure of the display protective adhesive film as shown in the table, the display protective adhesive films of Examples 2 to 4 were obtained in the same manner as in Example 1.

(Comparative Example 1)
A display protective pressure-sensitive adhesive film of Comparative Example 1 was obtained in the same manner as in Example 1 except that the methylolmelamine-based crosslinking agent was changed to an isocyanate-based crosslinking agent.

(Comparative Example 2)
As an antistatic agent, a display protective adhesive film of Comparative Example 1 was obtained in the same manner as in Example 1 except that a solution of benzalkonium chloride dissolved in ethanol was applied to a thickness of 20 nm.

(Comparative Example 3)
Urethane prepolymer having a hydroxyl group: 100 parts by mass (solid content), isocyanate crosslinking agent (“Coronate HL” manufactured by Tosoh Corporation): 10 parts by mass (solid content), 1-octyl-4-methylpyridinium bis (fluorosulfonyl) ) Imide: A 0.5 mass part mixture was diluted with MEK so that the solid content was 50 mass% to prepare a liquid pressure-sensitive adhesive composition.

  Next, the pressure-sensitive adhesive composition prepared as described above was subjected to a knife coater on the surface on which the silicone-treated polyester film having a thickness of 38 μm, which was a release liner, was peeled, so that the thickness of the pressure-sensitive adhesive layer after drying was reduced. It apply | coated so that it might be set to 20 micrometers, Then, it dried at 100 degreeC for 1 minute, and formed the adhesive layer.

  Thereafter, a polyethylene terephthalate film having a thickness of 50 μm was bonded as a base material on the pressure-sensitive adhesive layer to obtain a display-protective pressure-sensitive adhesive film of Comparative Example 3.

(Comparative Example 4)
In the pressure-sensitive adhesive composition, 1-octyl-4-methylpyridinium bis (fluorosulfonyl) imide: a pressure-sensitive adhesive film for display protection of Comparative Example 4 in the same manner as Comparative Example 3 except that 0.5 part by mass was omitted. Got.

In Table 1,
PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate)) A1, benzalkonium chloride A2, 1-octyl-4-methylpyridinium bis (fluorosulfonyl) A3 is an imide, PEs is a hydroxyl group-containing polyester, B1 is a methylolmelamine-based crosslinking agent, B2 is an isocyanate-based crosslinking agent, and M1 is a urethane prepolymer having a hydroxyl group.

[2] Evaluation <Antistatic property>
The release liner was peeled off from the test pieces of each of the above Examples and Comparative Examples, and was reciprocated once with a 2 kg roller against a previously neutralized glass plate. At this time, one end of the display-protective adhesive film protruded 1 cm from the glass plate.

  After leaving for 24 hours, the end portion on the side protruding from the glass plate was peeled off at a peeling angle of 180 degrees and a peeling speed of 10 m / min. Then, the stripping voltage was measured with an electrostatic potential measuring device (STATIRON-M2 manufactured by Sisid Electrostatic Co., Ltd.) fixed at a position 5 cm away from the adhesive film, and evaluated according to the following criteria.

A: The peeling voltage is less than 200V.
B: The peeling voltage is 200 V or more and less than 500 V.
C: The peeling voltage is 500 V or more and less than 1000 V.
D: The peeling voltage is 1000 V or more and less than 5000 V.
E: The peeling voltage is 5000 V or more.

<Haze>
The release liner was peeled off from the test pieces of the respective Examples and Comparative Examples to expose the pressure-sensitive adhesive layer. About the test piece of the adhesive film in the state where the adhesive layer was exposed, the haze (%) was measured using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH5000) according to JIS K7136: 2000. It evaluated according to.

A: Haze is less than 0.7%.
B: Haze is 0.7% or more and less than 1.0%.
C: Haze is 1.0% or more and less than 1.5%.
D: Haze is 1.5% or more and less than 2.0%.
E: Haze is 2.0% or more.

<Anti-fogging property due to migration of antistatic agent>
The release liner was peeled off from the test pieces of each of the above Examples and Comparative Examples, and was pressed once and again with a 2 kg roller against a glass plate.

  Next, after standing for 1 day in an environment of 23 ° C. and 50% RH (relative humidity), left for 7 days in an environment of 40 ° C. and 80% RH (relative humidity), and again at 23 ° C. and 50% RH. It returned to the environment of (relative humidity), and left still for 1 day.

  Thereafter, the pressure-sensitive adhesive film was peeled off at a peeling angle of 180 degrees and a peeling speed of 0.3 m / min.

A: The cloudiness of the part which stuck the adhesion film of the adherend was not recognized at all.
B: The cloudiness of the site | part which stuck the adhesion film of the to-be-adhered body is hardly recognized.
C: The cloudiness of the part which stuck the adhesion film of the to-be-adhered body was recognized slightly.
D: Although the cloudiness of the part which stuck the adhesion film of the to-be-adhered body is recognized, there is no trouble in visual recognition of the state of an to-be-adhered body.
E: The cloudiness of the part where the adhesive film of the adherend is stuck is noticeable, and the visibility of the state of the adherend is hindered.

<Alcohol resistance>
The release liner was peeled off from the test pieces of each of the above Examples and Comparative Examples, and was reciprocated once with a 2 kg roller against a previously neutralized glass plate. At this time, one end of the display-protective adhesive film protruded 1 cm from the glass plate.

  After leaving for 24 hours, the surface of each test piece was wiped with an alcohol towel “Alcohol towel capable of sterilizing erière” manufactured by Daio Paper Co., Ltd.

  Then, the edge part on the side protruding from the glass plate was peeled off so that the peeling angle was 180 degrees and the peeling speed was 10 m / min. Then, the stripping voltage was measured with an electrostatic potential measuring device (STATIRON-M2 manufactured by Sisid Electrostatic Co., Ltd.) fixed at a position 5 cm away from the adhesive film, and evaluated according to the following criteria.

A: The peeling voltage is less than 200V.
B: The peeling voltage is 200 V or more and less than 500 V.
C: The peeling voltage is 500 V or more and less than 1000 V.
D: The peeling voltage is 1000 V or more and less than 5000 V.
E: The peeling voltage is 5000 V or more.
These results are summarized in Table 1.

  The display protective adhesive film of each of the above examples was superior in antistatic property to the display protective adhesive film of each comparative example. Therefore, the display-protective adhesive film of each example has an antistatic property equivalent to or higher than that of a conventional product.

10 Display protective adhesive film 1 Base material 2 Adhesive layer 3 Antistatic layer

Claims (6)

A substrate;
An adhesive layer provided on one surface side of the substrate;
An antistatic layer provided on the other surface side of the base material and made of a material containing PEDOT: PSS (poly (3,4-ethylenedioxythiophene): poly (4-styrenesulfonate)); An adhesive film for protecting a display, comprising:   The pressure-sensitive adhesive film for display protection according to claim 1, wherein the antistatic layer is made of a material containing polyester having a hydroxyl group.   The pressure-sensitive adhesive film for display protection according to claim 1 or 2, wherein the visible light transmittance is 80% or more. The antistatic layer includes a binder resin and the PEDOT: PSS,
The display according to any one of claims 1 to 3, wherein a content of the PEDOT: PSS in the antistatic layer is 0.5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin. Protective adhesive film.   The said adhesive layer is a display protective adhesive film of any one of Claim 1 thru | or 4 containing a urethane type adhesive or an acrylic adhesive.   The display-protective pressure-sensitive adhesive film according to any one of claims 1 to 5, wherein the antistatic layer is composed of a material crosslinked with a methylolmelamine-based crosslinking agent.

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