JP2022146233A - marking film - Google Patents

Abstract

To provide a marking film that can easily remove an adhesive from an adherend without using an organic solvent.SOLUTION: A marking film has a substrate and an adhesive layer. The adhesive layer comprises a water-soluble compound including a polar functional group selected from the group consisting of a hydroxy group, an amino group, a carbonyl group and a benzoyl group and having a molecular weight of 1000 or less.SELECTED DRAWING: None

Description

The present invention relates to marking films.

Adhesive films called marking films are used for the purpose of outdoor billboards, outdoor signs, outdoor advertisements, vehicle advertisements, and the like. A marking film has a configuration in which an adhesive layer is laminated on one side of a base film.・Advertisement effects can be brought about by images and the like.

As described above, the marking film may be used for advertisement or publicity purposes, so it may be necessary to reattach it to another marking film after a certain period of time has elapsed. At this time, it is necessary to peel off the marking film from the adherend, but since the adhesive of the marking film has relatively strong adhesiveness, it is not easy to peel off the marking film from the adherend. Furthermore, when the marking film is peeled off from the adherend, the adhesive may remain on the surface of the adherend.

In Patent Document 1, an acrylic white pressure-sensitive adhesive containing a specific polymer is laminated on a colored base film to improve the adhesion between the colored film layer and the pressure-sensitive adhesive layer, thereby leaving the pressure-sensitive adhesive component on the adherend. It says that it can be peeled off without In this way, the remaining of the adhesive on the adherend, the so-called adhesive residue, has been studied so far.

JP 2009-203370 A

In particular, when the marking film is peeled off from the adherend after a long period of time or when exposed to high temperatures such as in direct sunlight, the adhesive may remain on the surface of the adherend. In such a case, it was necessary to remove the adhesive on the adherend by, for example, wiping off with an organic solvent.

However, if an organic solvent is used, the signboard or the coating of the vehicle, which is the adherend, may come off, and the use of the organic solvent is a problem to be considered.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a marking film that can be easily peeled off from an adherend without using an organic solvent. Another object of the present invention is to provide a marking film from which an adhesive can be easily removed from an adherend without using an organic solvent.

The present invention is a marking film having a substrate and an adhesive layer, wherein the adhesive layer has a polar functional group selected from the group consisting of a hydroxyl group, an amino group, a carbonyl group and a benzoyl group. and a water-soluble compound having a molecular weight of 1000 or less.

The marking film of the present invention can be easily peeled off from an adherend using an aqueous solvent. Moreover, according to the marking film of the present invention, the adhesive remaining on the adherend can be easily removed using an aqueous solvent.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the marking film.

The present embodiment will be described in detail below.

In this specification, "X to Y" indicating a range means "X or more and Y or less". In addition, unless otherwise specified, operations, physical properties, etc. are measured under the conditions of room temperature (20 to 25° C.)/relative humidity of 45 to 55% RH. As used herein, "(meth)acrylate" refers to "acrylate or methacrylate" and "(meth)acrylic acid" refers to "acrylic acid or methacrylic acid."

A first embodiment of the present invention is a marking film having a substrate and an adhesive layer, wherein the adhesive layer has a polarity selected from the group consisting of hydroxyl groups, amino groups, carbonyl groups and benzoyl groups. A marking film containing a water-soluble compound having a functional group and a molecular weight of 1000 or less.

When the water-soluble compound contained in the adhesive layer in the marking film of the first embodiment comes into contact with an aqueous solvent by wiping with water or spraying, the cohesive force of the adhesive is reduced, and the adhesive is easily peeled off from the adherend. It is thought that

Therefore, the marking film of the first embodiment can be easily peeled off from the adherend using an aqueous solvent. Even if the adhesive remains on the surface of the adherend after the marking film is peeled off from the adherend, it can be easily removed with an aqueous solvent (for example, by wiping). Hereinafter, the property of a film that can be easily peeled off from an adherend with an aqueous solvent is also referred to as water peeling property. In addition, hereinafter, the property of an adhesive that can be easily removed from an adherend (for example, by wiping) with an aqueous solvent is also referred to as water removal property.

FIG. 1 is a schematic cross-sectional view showing a marking film. In FIG. 1, a marking film 10 is composed of a substrate 11, an adhesive layer 12, and a release liner 13. As shown in FIG. The substrate 11 is arranged adjacent to the adhesive layer 12 . When applying, the release liner 13 is removed from the marking film 10, and the exposed adhesive layer 12 is used to apply the marking film to the adherend.

In FIG. 1, the laminate has a substrate 11, an adhesive layer 12, and a release liner 13 in this order. and/or there may be other intermediate layers between the substrate and the adhesive layer.

The marking film preferably has an adhesive strength of 2 N/25 mm or more, more preferably 4 N/25 mm or more, and even more preferably 5 N/25 mm or more. Adhesiveness to adherends is ensured when the adhesive strength of the marking film is equal to or higher than the above lower limit. A marking film needs to be attached to an adherend for a long time, and requires a certain degree of tackiness. Although the upper limit of the adhesive strength is not particularly limited, it is 15 N/25 mm or less. In addition, the adhesive strength adopts the value measured by the method described in the following examples.

Each constituent member constituting the marking film will be described below.

[Adhesive layer]
The adhesive layer contains an adhesive and a water-soluble compound having a polar functional group (hereinafter also simply referred to as a water-soluble compound). Here, the term “water-soluble” refers to a compound that dissolves in 100 g of water (25° C.) by 1 g or more, preferably 3 g or more, more preferably 10 g or more.

Polar functional groups in water-soluble compounds are hydroxyl, amino, carbonyl and benzoyl groups. Among them, the polar functional group is preferably a hydroxyl group or an amino group, and more preferably a hydroxyl group, because the water removing property of the adhesive remaining on the adherend is improved.

Compounds having an amino group include polyethyleneimine, propylene oxide-modified polyethyleneimine, polyvinylamine, and the like.

Compounds having a carbonyl group include 2-pyrrolidone and triethyl citrate.

As the water-soluble compound having a hydroxyl group, a polyhydric alcohol or a polyhydric alcohol derivative is preferred because the water-releasing property from the adherend and/or the water-removing property of the pressure-sensitive adhesive remaining on the adherend are further improved. is preferred.

Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tripropylene glycol, propylene glycol, 1,3-propanediol, dipropylene glycol, 1,3-butylene glycol, polyethylene glycol, glycerin, diglycerin, Polyglycerin, pentanediol, hexamethylene glycol and the like. These may be used individually by 1 type, or may be used together 2 or more types. Among them, the polyhydric alcohol is preferably at least one selected from the group consisting of ethylene glycol, triethylene glycol, polyethylene glycol, and glycerin.

Polyhydric alcohol derivatives include polyhydric alcohol monoalkyl ethers (polyhydric alcohol ethers) having a hydroxyl group such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, and ethylene glycol monoethyl ether. .

In addition, as the water-soluble compound, polyhydric alcohol, polyhydric alcohol derivative and polyethyleneimine are selected because the water release property from the adherend and/or the water removal property of the adhesive remaining on the adherend are further improved. It is preferably at least one selected from the group consisting of: Furthermore, from the viewpoint of improving adhesiveness, the water-soluble compound is more preferably a polyhydric alcohol.

The molecular weight of the water-soluble compound is 1000 or less. If the molecular weight of the water-soluble compound exceeds 1,000, the solubility in water decreases, resulting in a decrease in water stripping property and/or water removing property. The molecular weight of the water-soluble compound is preferably 800 or less, more preferably 500 or less. The lower limit of the molecular weight of the water-soluble compound is usually 30 or more, and may be 50 or more.

One type of water-soluble compound may be used alone, or two or more types may be used in combination.

The amount of the water-soluble compound to be added is appropriately set depending on the type of adhesive used, the type of the water-soluble compound, and the like. Since the effect of water removability and/or water wiping property is further exhibited, the amount of the water-soluble compound added should be 0.5% by mass or more relative to the pressure-sensitive adhesive (for example, acrylic copolymer). is preferred, 1% by mass or more is more preferred, and 3% by mass or more is even more preferred. Further, from the viewpoint of adhesiveness, the amount of the water-soluble compound added is preferably 30% by mass or less, more preferably 25% by mass or less, relative to the pressure-sensitive adhesive (eg, acrylic copolymer). .

The adhesive is not particularly limited, and for example, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a polyurethane adhesive, a polyester adhesive, or the like can be used. As the adhesive, an acrylic adhesive can be particularly preferably used from the viewpoint of adhesion reliability.

The acrylic copolymer that constitutes the acrylic pressure-sensitive adhesive has (meth)acrylic acid alkyl ester as the main monomer component, and if necessary, a monomer (copolymer) that can be copolymerized with (meth)acrylic acid alkyl ester polymerizable monomer). Here, the main component refers to 50% by mass or more (upper limit of 100% by mass) in the monomer, preferably 65% by mass or more, more preferably 85% by mass or more.

Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and n-butyl (meth)acrylate. , isobutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, ( decyl meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. These may be used alone or in combination of two or more. Among them, as the alkyl (meth)acrylate, n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate is preferably used in consideration of adhesiveness, and 2-ethylhexyl (meth)acrylate is used. It is more preferable to use 2-ethylhexyl acrylate because sufficient adhesive strength can be obtained even in a low-temperature environment. When using n-butyl (meth)acrylate and/or 2-ethylhexyl (meth)acrylate, it is preferably 70 to 97% by mass, preferably 80 to 95% by mass, based on the total amount of monomers. is more preferred.

In addition, from the viewpoint of adhesiveness, it is preferable to use methyl (meth)acrylate in combination with n-butyl (meth)acrylate and/or 2-ethylhexyl (meth)acrylate, and it is possible to combine methyl methacrylate. more preferred. The content of methyl (meth)acrylate is preferably 0.5 to 25% by mass, more preferably 1 to 20% by mass, more preferably 5 to 20% by mass, relative to the total amount of monomers. It is even more preferred to have

Examples of copolymerizable monomers copolymerizable with (meth)acrylic acid alkyl esters include carboxyl-containing monomers such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Monomers or their anhydrides; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerin dimethacrylate hydroxyl group-containing monomers such as; amide group-containing monomers such as acrylamide, methacrylamide, N-vinylpyrrolidone, and N,N-dimethylacrylamide; amino groups such as aminoethyl (meth)acrylate and (meth)acryloylmorpholine Containing monomers; aromatic vinyl compounds such as styrene and substituted styrene; cyano group-containing monomers such as acrylonitrile; and vinyl esters such as vinyl acetate. These may be used alone or in combination of two or more.

A carboxyl group-containing monomer or an anhydride thereof is used as a copolymerizable monomer that can be copolymerized with the (meth)acrylic acid alkyl ester because it improves the dispersion stability of the emulsion polymer, which is a preferred form among them. is preferably used. Carboxyl group-containing monomers include (meth)acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, myristoleic acid, palmitoleic acid, and oleic acid. Examples of anhydrides of carboxyl group-containing monomers include maleic anhydride and itaconic anhydride. Among them, (meth)acrylic acid is more preferably used as the copolymerizable monomer that can be copolymerized with the (meth)acrylic acid alkyl ester, and acrylic acid is further preferably used.

When a carboxyl group-containing monomer or its anhydride is used, the content in the total monomer is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass. Preferably, it is 1 to 5% by mass, even more preferably.

The content of the acrylic copolymer in the pressure-sensitive adhesive layer is preferably 50 to 99.5% by mass, more preferably 60 to 99% by mass, and further preferably 80 to 97% by mass. more preferred.

The method for producing the acrylic copolymer is not particularly limited, and conventional methods such as solution polymerization using a polymerization initiator, emulsion polymerization, suspension polymerization, reverse phase suspension polymerization, thin film polymerization, spray polymerization, etc. A known method can be used. In addition to the method of initiating polymerization with a polymerization initiator, a method of initiating polymerization by irradiation with radiation, electron beams, ultraviolet rays, or the like can also be employed. Among them, it is preferable to use the emulsion polymerization method because the effect of the present invention is more exhibited. That is, in a preferred embodiment of the present invention, the acrylic copolymer is an emulsion polymer.

When the acrylic copolymer is an emulsion polymer, the acrylic copolymer is preferably not crosslinked with a crosslinking agent. That is, the acrylic copolymer is preferably non-crosslinked.

The emulsion polymerization method includes, for example, a method in which an emulsifier and a polymerization initiator are added to a monomer mixture containing the above-described monomers, and emulsion polymerization is performed.

In the emulsion polymerization, from the viewpoint of polymerization stability, the monomer mixture contains an emulsifier (or part of the emulsifier) dissolved in the monomer mixture, or an O/W emulsion in advance. It is preferable to keep the state of

Procedures for carrying out emulsion polymerization include, for example, the following methods (1) to (3).
(1) The total amount of the monomer mixture, emulsifier, water, etc. is charged, the temperature is raised, and the total amount of the polymerization initiator dissolved in water is added dropwise or dividedly to polymerize.
(2) Water, an emulsifier, and a portion of the monomer mixture are charged into a reaction vessel, and after the temperature is raised, a polymerization initiator dissolved in water is added dropwise or dividedly to allow the polymerization reaction to proceed, and then the remaining The total amount of the monomer mixture is added dropwise or dividedly to continue the polymerization.
(3) A polymerization initiator dissolved in water is placed in a reaction vessel, and after the temperature is raised, an emulsified liquid consisting of a monomer mixture, an emulsifier, and water is added dropwise or dividedly to polymerize.

The emulsifier is not particularly limited, but from the viewpoint of improving the dispersion stability of the emulsion polymer, an anionic emulsifier or nonionic emulsifier is preferred, and an anionic emulsifier is more preferred.

Examples of anionic emulsifiers include sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, and allyl alkyl. sulfosuccinic acid ester salts and the like. Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers. These emulsifiers may be used alone or in combination of two or more.

The amount of the emulsifier to be added is preferably 0.5 per 100 parts by mass of the monomer mixture, from the viewpoint of the stability of the emulsion polymerization reaction and from the viewpoint of preventing physical property deterioration due to the remaining unreacted emulsifier. 12 parts by mass, more preferably 0.5 to 8 parts by mass, still more preferably 0.7 to 6 parts by mass.

The emulsifier may be added directly to a solution obtained by adding water to the monomer mixture, or may be added to the polymerization vessel in advance, or may be used in combination.

The polymerization initiator may be either water-soluble or oil-soluble. Examples include 2,2'-azobis(2-methylpropionamidine) dihydrochloride and 2,2'-azobis(2-amidinopropane) azo compounds such as dihydrochloride; persulfates such as potassium persulfate, sodium persulfate and ammonium persulfate; peroxides such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; Redox initiators such as a combination of salt and sodium bisulfite or a combination of peroxide and sodium ascorbate may also be used. You may use a polymerization initiator individually or in combination of 2 or more types. Among these, persulfates or redox initiators are preferred from the viewpoint of excellent polymerization stability.

The amount of the polymerization initiator to be added is preferably 0.01 to 6 parts by mass, more preferably 0.03 to 4 parts by mass, still more preferably 0.03 to 4 parts by mass, with respect to 100 parts by mass of the monomer mixture, from the viewpoint of increasing the polymerization rate. is 0.1 to 2 parts by mass.

The polymerization initiator may be added in advance to the reaction vessel, may be added immediately before the initiation of polymerization, may be added in multiple portions after the initiation of polymerization, or may be added in advance to the monomer mixture. may be added to the emulsified liquid after preparing the emulsified liquid comprising the monomer mixture.

Further, a known chain transfer agent or pH buffer may be added during emulsion polymerization.

Ion-exchanged water is preferable as the water used in the emulsion polymerization. The amount of water to be used is preferably 30 to 400 parts by mass, more preferably 35 to 200 parts by mass, still more preferably 40 to 150 parts by mass with respect to 100 parts by mass of the monomer mixture.

An aqueous alkali solution such as aqueous ammonia, various water-soluble amines, an aqueous sodium hydroxide solution, or an aqueous potassium hydroxide solution is added to the emulsion polymer dispersion obtained by emulsion polymerization to adjust the pH to 5 to 9 (preferably It is preferable to adjust the pH to 6 to 8.5).

The solid content concentration of the emulsion polymer dispersion is preferably 10 to 80% by mass, more preferably 25 to 70% by mass, still more preferably 45 to 65% by mass.

The viscosity of the emulsion polymer dispersion at 25° C. is preferably 50 to 12,000 mPa·s, more preferably 100 to 10,000 mPa·s, still more preferably 200 to 9,000 mPa·s. As used herein, viscosity is a value measured using a B-type rotational viscometer.

The emulsion polymer has an emulsion shape (particle shape) in which the emulsion polymer is dispersed. At this time, the average particle size of the emulsion polymer is preferably 500 nm or less, more preferably 300 nm or less, and still more preferably 200 nm or less. The average particle size of the emulsion polymer is usually 50 nm or more, more preferably 100 nm or more. Here, the average particle size of the emulsion polymer is a volume-based median size measured by a laser diffraction dispersion method.

The adhesive layer may contain a tackifier. The tackifier is not particularly limited, and examples thereof include alicyclic petroleum resins, terpene-based resins, polymerized rosin-based ester resins, and styrene-based resins.

The pressure-sensitive adhesive layer may further contain other conventionally known additives. Examples of such additives include fillers, pigments, ultraviolet absorbers, and the like. Examples of fillers include zinc white, silica, calcium carbonate, and the like.

The method of forming the pressure-sensitive adhesive layer is not particularly limited, but the pressure-sensitive adhesive layer is formed by directly applying the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer (hereinafter also simply referred to as the pressure-sensitive adhesive composition) on the substrate. Alternatively, a pressure-sensitive adhesive layer may be formed on the release liner and then laminated to the substrate. Specifically, a method of applying a pressure-sensitive adhesive composition onto a release liner and transferring a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition to a substrate can be mentioned.

The method of applying the pressure-sensitive adhesive composition to the substrate or release liner is not particularly limited. It can be applied using an applicator.

The thickness of the pressure-sensitive adhesive layer (thickness after drying) is usually 5 to 100 μm, preferably 10 to 50 μm.

<Base material>
Examples of the base material include, but are not particularly limited to, paper base materials such as kraft paper and Japanese paper, resin base materials, and synthetic paper. Among them, from the viewpoint of durability, the substrate is preferably a resin substrate.

As the resin constituting the resin base material, for example, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA) and other α- Olefin-based resins containing olefin as a monomer component; polyester-based resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); polyvinyl chloride (PVC); vinyl acetate-based resins; polycarbonate (PC ); acrylic resin; polyurethane, and the like. These resins may be used alone or in combination of two or more. Among these, from the viewpoint of weather resistance and flexibility, polyvinyl chloride, acrylic resin, and polyurethane are preferable as the resin constituting the resin base material.

Synthetic papers include, for example, polyester films and polypropylene films having microvoids.

The thickness of the substrate is appropriately selected depending on the type of substrate used, and is preferably 10-200 μm, more preferably 20-150 μm, and even more preferably 30-100 μm.

The substrate may be transparent or opaque.

Also, the substrate may be colored or colorless. If colored, any colorant can be used. The colored base material can be produced by blending the colorant with the raw material resin, melt-kneading and forming into a film, or by casting onto a process film, drying and forming into a cast film. you can go

The substrate may contain various additives such as ultraviolet absorbers, plasticizers, heat stabilizers, dispersion solvents, diluent dispersion solvents, and the like. Examples of ultraviolet absorbers include salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazole-based ultraviolet absorbers. Examples of plasticizers include phosphoric acid-based plasticizers, phthalic acid-based plasticizers, adipic acid-based plasticizers, and polyester-based plasticizers. Examples of heat stabilizers include lead salt-based heat stabilizers, metal soap-based heat stabilizers, organotin compound-based heat stabilizers, and the like. Examples of dispersion solvents include ketones such as diisobutyl ketone and methyl isobutyl ketone, esters such as butyl acetate, and glycol ethers such as butyl cellosolve. Examples of the diluting dispersion solvent include paraffinic hydrocarbons, naphthenic hydrocarbons, aromatic hydrocarbons, and terpenes.

When the pressure-sensitive adhesive layer is provided on one side of the substrate, one side of the substrate may be surface-treated in order to improve adhesion with the pressure-sensitive adhesive layer. Examples of surface treatment include corona discharge treatment, plasma treatment, and primer treatment.

<Release liner>
The marking film may contain a release liner. A release liner is a member that is used before attaching an adhesive film to an adherend and has a function of protecting the adhesive layer and preventing deterioration of adhesiveness before use.

Examples of the release liner include, but are not limited to, polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; plastic films such as polyolefin films such as polypropylene and polyethylene; Paper such as clay coated paper can be used.

The thickness of the release liner is not particularly limited, but is usually 10-400 μm. Moreover, a layer made of a release agent made of silicone or the like may be provided on the surface of the release liner to improve the releasability from the pressure-sensitive adhesive layer.

<Application of marking film>
On the surface of the marking film 10 according to one embodiment of the present invention that is not in contact with the adhesive layer 12 of the substrate 11, a color or pattern is applied by a method such as inkjet printing via an ink-receiving layer or the like as necessary. may be applied. By removing the release liner 13 and applying the exposed pressure-sensitive adhesive layer 12 to the surface of the adherend, the marking film can be applied to the substrate 11 while concealing the color and pattern of the adherend. It is possible to present a selected color or pattern on the adherend. Furthermore, the adherend to which this marking film is attached can be easily peeled off from the adherend with an aqueous medium even after being attached in an outdoor environment for a certain period of time. Even if the adhesive remains on the adherend after the film is peeled off from the adherend, the adhesive can be easily removed by wiping with a damp cloth. Therefore, the marking film according to one embodiment of the present invention can be suitably used for the purpose of decorating adherends used outdoors (signboards, advertisements, vehicles, buildings, traffic signs, etc.) for a certain period of time. can.

<Method of removing marking film from adherend>
A second embodiment of the present invention is a method for peeling a marking film from an adherend, wherein the film is peeled from the adherend using an aqueous solvent. In the marking film of the first embodiment, the adhesive layer contains a water-soluble compound having a polar functional group and a molecular weight of 1000 or less. Therefore, by using a water-based solvent, the marking film can be easily and simply peeled off from the adherend (without using an organic solvent that affects coating, etc.).

An aqueous solvent refers to a solvent containing 60% by mass or more (upper limit of 100% by mass) of water, preferably 70% by mass or more, more preferably 85% by mass or more, and most preferably water.

Examples of components other than water contained in the aqueous solvent include an organic solvent that dissolves in water; and a surfactant. Examples of water-soluble organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, dimethylformamide, methyl cellosolve, and tetrahydrofuran.

Examples of the method of peeling the marking film from the adherend include a method in which the marking film is slightly peeled off from the adherend and then peeled off while spraying an aqueous solvent onto the interface between the marking film and the adherend. In the case of spraying the aqueous solvent, the aqueous solvent may be sprayed at high pressure.

<Method for removing adhesive>
The third embodiment of the present invention is a method of removing the adhesive from the adherend using an aqueous solvent when the adhesive of the marking film of the first embodiment remains on the adherend. As described above, the marking film of the first embodiment can be easily peeled off from the adherend using an aqueous solvent. Excellent for

As the aqueous solvent, the same one as described in the section of the second embodiment can be used.

Specifically, the method of removing the adhesive from the adherend using an aqueous solvent includes wiping the surface of the adherend with a cloth or non-woven fabric containing the aqueous solvent; spraying the aqueous solvent at high pressure, etc. mentioned.

The effects of the present invention will be described using the following examples and comparative examples. Although "parts" or "%" may be used in the examples, "parts by mass" or "% by mass" are indicated unless otherwise specified. Moreover, unless otherwise specified, each operation is performed at room temperature (25° C.).

(Example 1)
84 parts by mass of 2-ethylhexyl acrylate, 12.5 parts by mass of methyl methacrylate and 3.5 parts by mass of acrylic acid as raw material monomers and an emulsifier as Add 4 parts by mass of sodium lauryl sulfate ("Emal AD-25R" manufactured by Kao Corporation) (0.96 parts by mass in terms of solid content) and 35 parts by mass of degassed ion-exchanged water, and stir to form an emulsion. prepared.

Separately, 40 parts by mass of degassed ion-exchanged water was put into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel, and the temperature was raised to 80°C. Next, the emulsion was transferred to a dropping funnel and added dropwise over 4 hours. At the same time, 4 parts by mass of an aqueous potassium persulfate solution having a concentration of 3% by mass was added dropwise as a polymerization initiator solution, and emulsion polymerization was carried out at a reaction temperature of 80°C. After completion of dropping, aging was carried out at 80° C. for 2 hours to obtain an emulsion polymerization composition. After that, the mixture was cooled to room temperature and adjusted to pH 7.0 with 25% by mass of aqueous ammonia and 25% by mass of sodium hydroxide aqueous solution to obtain an aqueous acrylic polymer dispersion.

1 part by mass of ethylene glycol was added to 100 parts by mass of the solid content of the obtained acrylic polymer aqueous solution to obtain a pressure-sensitive adhesive composition.

After applying the obtained pressure-sensitive adhesive composition to the release agent-coated surface of a release liner made by coating a polyethylene terephthalate film having a thickness of 38 μm with a silicone-based release agent to a thickness of 0.1 μm with a knife coater so as to give a dry film thickness of 15 μm. , and dried at 90°C to obtain a laminate of a release liner and an adhesive layer.

A polyvinyl chloride film having a thickness of 50 μm was laminated as a substrate to the pressure-sensitive adhesive layer surface of the laminate to obtain a marking film.

(Example 2)
A marking film was obtained in the same manner as in Example 1, except that the amount of ethylene glycol added was 10 parts by mass.

(Example 3)
A marking film was obtained in the same manner as in Example 1, except that the amount of ethylene glycol added was 20 parts by mass.

(Example 4)
A marking film was obtained in the same manner as in Example 2, except that ethylene glycol was changed to triethylene glycol.

(Example 5)
A marking film was obtained in the same manner as in Example 2, except that ethylene glycol was changed to polyethylene glycol (molecular weight: 600).

(Example 6)
A marking film was obtained in the same manner as in Example 2, except that ethylene glycol was changed to glycerin.

(Example 7)
A marking film was obtained in the same manner as in Example 2, except that ethylene glycol was changed to polyethyleneimine (molecular weight: 600, Epomin SP-006 manufactured by Nippon Shokubai Co., Ltd.).

(Comparative example 1)
A marking film was obtained in the same manner as in Example 1, except that ethylene glycol was not added.

(Measurement method: adhesive strength)
The marking films obtained in Examples and Comparative Examples were allowed to stand under a standard environment (23°C, 50% RH) for one day, the release liner was peeled off, and the adhesive layer surface was attached to a SUS plate (SUS304 steel plate). was measured. Specifically, the sheet was peeled off in a 180° direction at a test speed of 300 mm/min using a tensile tester, and the adhesive force was measured. The numerical value is converted into peeling force per sheet width of 25 mm (N/25 mm). Table 1 shows the results.

(Evaluation method: wiping test)
In Examples and Comparative Examples, no polyvinyl chloride film was attached, and instead, a release liner was attached. One release liner was peeled off, an adhesive (15 μm) was applied to the melamine-coated plate, and the plate was allowed to stand at 40° C. for 7 days. After peeling off the other release liner, the adhesive surface was wiped back and forth 20 times with a wiper containing water (BENCOT (registered trademark), manufactured by Asahi Kasei Corporation), and then the appearance was evaluated.

○: Completely wiped off,
△: Partially wiped off,
x: Could not be wiped off.

(Evaluation method: ease of peeling when sprayed with water)
The marking films obtained in Examples and Comparative Examples were allowed to stand under a standard environment (23°C, 50% RH) for one day, the release liner was peeled off, and the pressure-sensitive adhesive layer surface was attached to a melamine-coated plate. It was left still for 7 days. After peeling off the edge of the marking film, while spraying water onto the interface between the marking film and the adherend at a water pressure of 10 MPa, the film was pulled off while holding the edge. The easiness of peeling at that time was evaluated.

◯: Easily peelable △: Resistance is large, but peelable ×: Not peelable.

Table 1 shows the results.

As can be seen from the above results, the marking films of Examples 1 to 7 can be easily peeled off from the adherend with water, and the adhesive residue remaining on the adherend can be removed by wiping with a damp cloth. did it.

10 marking film,
11 base material,
12 adhesive layer,
13 Release liner.

Claims (4)

A marking film having a substrate and an adhesive layer,
A marking film, wherein the pressure-sensitive adhesive layer contains a water-soluble compound having a polar functional group selected from the group consisting of a hydroxyl group, an amino group, a carbonyl group and a benzoyl group and having a molecular weight of 1000 or less. 2. The marking film according to claim 1, wherein said water-soluble compound is at least one selected from the group consisting of polyhydric alcohols, polyhydric alcohol derivatives and polyethyleneimine. The marking film according to claim 1 or 2, wherein the pressure-sensitive adhesive layer contains an emulsion acrylic copolymer. The method for removing a marking film from an adherend according to any one of claims 1 to 3, wherein the marking film is removed from the adherend using an aqueous solvent.

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