JP7598261B2 - Functional adhesive composition, functional adhesive film, and method of using same - Google Patents

Description

This application relates to a functional adhesive film that can be easily applied to cracked cement-based structures during inspection, can be peeled off when necessary, and can prevent the spread of cracks in the cement-based structure during application, as well as a method for using the same and a functional adhesive composition for use in the functional adhesive film.

Over time, concrete structures used in bridges, tunnels, etc. can develop cracks due to fatigue, salt damage, alkali-aggregate reaction, etc. If the concrete remains in a cracked state for a long period of time, rainwater, carbon dioxide, etc. can penetrate deep into the concrete through the cracks, corroding the rebar and reducing the strength of the concrete itself, which can lead to serious accidents such as the collapse of bridges and tunnels. In light of this situation, a framework has been established to ensure that inspections of infrastructure such as concrete structures are carried out once every five years.

Although it depends on the environmental conditions, leaving cracks unattended means that concrete deterioration will progress, so it is desirable to be able to take some kind of action. For this reason, repair measures are necessary at an early stage when cracks appear in concrete. As a method for repairing cracks in concrete, a method has been proposed in which a primer consisting of an aqueous solution containing an alkali metal silicate is applied and allowed to penetrate into the crack, and then a putty material having inorganic filler dispersed therein is filled into the crack to repair the crack (e.g., Patent Document 1), and a method of applying a paste containing a self-repairing material along the cracked portion of the concrete (e.g., Patent Document 2).

Furthermore, technical documents related to the invention disclosed in this application include Patent Document 3, which relates to an easily peelable adhesive tape, Patent Document 4, which relates to an adhesive composition and an adhesive tape, and Patent Document 5, which relates to an adhesive tape and a method for using the same.

JP 2010-001195 A JP 2013-014453 A JP 2017-222799 A JP 2002-069405 A JP 2020-132886 A

The method of directly filling or applying repair material to cracks as described in Patent Documents 1 and 2 requires large-scale construction work, such as setting up scaffolding and having repair work done by experts. On the other hand, when it comes to maintaining concrete structures in local governments, there are problems such as the inability to secure sufficient repair funds and unclear judgments about the deterioration grade associated with cracks, making it difficult for inspectors to deal with relatively wide cracks they find during inspections on the spot.

In order to solve the above problems, the inventors have proposed an adhesive tape that can be easily peeled off without leaving any adhesive residue when necessary, and that can suppress deterioration of cement-based structures (for example, Patent Document 5). This previously proposed adhesive tape was designed based on the standard pressure-bonding condition for cement-based structures, which is to use a 2 kg roller and make one reciprocating motion.

However, when applying adhesive tape to actual bridges, tunnels, etc., it is often applied to ceiling or sidewall surfaces, and in such cases it can be difficult to apply the same pressure at the actual repair site as when a 2 kg roller is used for one round trip application. This can result in insufficient adhesion of the adhesive tape, making it difficult to maintain the adhesiveness of the adhesive tape to cement-based structures over an extended period of time.

The present application has been made to solve the above problems, and provides a functional adhesive film that can be easily applied by an inspector who finds a crack in a cement-based structure, can be easily peeled off without leaving any glue residue if necessary, can suppress deterioration of the cement-based structure during application, and can maintain adhesion for a long period of time even when applied to the cement-based structure with a smaller pressure-applying force, a method for using the same, and a functional adhesive composition for use in the functional adhesive film.

The functional adhesive composition of the present application includes a side chain crystallized polymer, a first rubber resin that does not have fluidity at temperatures between -1°C and 40°C, a second rubber resin that has fluidity at temperatures between -1°C and 40°C, and a tackifier, the content ratio of the first rubber resin to the second rubber resin is 8:2 to 4:6 by mass, the content of the side chain crystallized polymer is 1 to 20 parts by mass per 100 parts by mass of the total mass of the first rubber resin and the second rubber resin, and the content of the tackifier is 5 to 15 parts by mass per 100 parts by mass of the total mass of the first rubber resin and the second rubber resin.

The functional adhesive film of the present application includes a substrate, an adhesive layer, and a functional adhesive layer in this order, the adhesive layer includes an adhesive, and the functional adhesive layer includes the functional adhesive composition of the present application.

The method of using the functional adhesive film of the present application includes the steps of preparing the functional adhesive film of the present application, attaching the functional adhesive layer side of the functional adhesive film to a deteriorated portion of a cement-based structure and then pressing the functional adhesive film with a predetermined pressure, leaving the cement-based structure to which the functional adhesive film has been attached and pressed in a natural environment for a certain period of time, heating the functional adhesive film after leaving the functional adhesive film to reduce the adhesive strength of the functional adhesive film, and peeling off the functional adhesive film with reduced adhesive strength from the cement-based structure.

The present application provides a functional adhesive film that can be attached by a simple method by an inspector of a cement-based structure immediately after inspection, can be easily peeled off when necessary without leaving any adhesive residue, can sufficiently suppress deterioration of the cement-based structure caused by cracks, and can maintain adhesion for a long period of time even when pressed against the cement-based structure with a smaller pressure force, a method for using the same, and a functional adhesive composition for use in the functional adhesive film.

FIG. 1 is a schematic cross-sectional view showing an example of a functional adhesive film according to an embodiment. FIG. 2 is a schematic cross-sectional view showing another example of the functional adhesive film according to the embodiment. FIG. 3 is a schematic cross-sectional view showing an example of a state in which the functional adhesive film of the embodiment is attached to a crack in a cement-based structure. FIG. 4 is a schematic cross-sectional view showing an example of a state in which the functional adhesive film of the embodiment attached to a cement-based structure is being heated. FIG. 5 is a schematic cross-sectional view showing an example of a state in which the functional adhesive film of the embodiment has been peeled off from a crack in a cement-based structure. FIG. 6 is a schematic cross-sectional view showing an example of a state in which a conventional adhesive film has been peeled off from a crack in a cement-based structure.

(Functional adhesive composition)
An embodiment of the functional adhesive composition of the present application will be described. The functional adhesive composition of this embodiment comprises a side chain crystallized polymer and a first rubber that does not have fluidity at temperatures of -1°C to 40°C. a first rubber-based resin, a second rubber-based resin having fluidity at temperatures of -1°C to 40°C, and a tackifier, is in a mass ratio of 8:2 to 4:6, and the content of the side chain crystallized polymer is 100 parts by mass of the total mass of the first rubber resin and the second rubber resin. and the content of the tackifier is 5 to 15 parts by mass relative to 100 parts by mass of the total mass of the first rubber resin and the second rubber resin. It is.

The functional adhesive composition of this embodiment contains a first rubber-based resin that has no fluidity at temperatures between -1°C and 40°C, a second rubber-based resin that has fluidity at temperatures between -1°C and 40°C, and a tackifier, so that even if applied to a cement-based structure with a smaller pressure, it can maintain adhesion for a long period of time and its adhesive strength can be reduced when heated to 50°C or higher.

The components of the functional adhesive composition of this embodiment are described below.

[Side Chain Crystallizing Polymer]
The side chain crystallizable polymer is a component that imparts a function of reducing the adhesive strength of the functional adhesive composition when heated at 50° C. or higher.

The side-chain crystallized polymer preferably has an endothermic peak of 50°C or higher as measured by differential scanning calorimetry (DSC). DSC is a thermal analysis method that measures the melting point of a measurement sample by measuring the difference in heat between the measurement sample and a reference substance using a differential scanning calorimeter, and α-alumina or the like can be used as the reference substance.

The side-chain crystallizing polymer is preferably a copolymer of a linear acrylate having an alkane chain with 18 or more carbon atoms and an acrylic monomer having a solubility parameter (SP value) of 7.3 to 9.5.

As the linear acrylate having an alkane chain having 18 or more carbon atoms, for example, stearyl acrylate, behenyl acrylate, lignocerityl acrylate, cerotinyl acrylate, montanyl acrylate, melissinyl acrylate, etc. can be used. By using the linear acrylate, the endothermic peak of the side chain crystallized polymer measured by DSC can be made to be 50°C or higher.

In addition, examples of acrylic monomers having a solubility parameter of 7.3 to 9.5 that can be used include acrylic acid, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, and butyl methacrylate. By using the acrylic monomers, the compatibility between the side chain crystallized polymer and other components of the functional adhesive composition can be improved.

The weight average molecular weight of the side chain crystallized polymer is preferably 1,000 to 15,000, and more preferably 5,000 to 12,000.

The content of the side chain crystallized polymer in the functional adhesive composition is 1 to 20 parts by mass, and more preferably 1 to 7 parts by mass, relative to 100 parts by mass of the total mass of the first rubber resin and the second rubber resin. If the content is less than 1 part by mass, the adhesive strength does not decrease even when heated to 50°C or higher. If the content is more than 20 parts by mass, the adhesive strength may decrease before heating to 50°C.

[First rubber resin and second rubber resin]
The first rubber-based resin is a rubber-based resin that does not have fluidity at temperatures of −1° C. to 40° C., and the second rubber-based resin is a rubber-based resin that has fluidity at temperatures of −1° C. to 40° C. The first rubber-based resin and the second rubber-based resin are components that impart a function that enables the functional adhesive composition of the present embodiment to maintain adhesion for a long period of time even when applied to a cement-based structure with a smaller pressure-bonding force.

The first rubber-based resin is not particularly limited as long as it is a rubber-based resin that does not have fluidity at temperatures between -1°C and 40°C. For example, butyl rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, etc. can be used, but butyl rubber-based resin is preferable in terms of cost, durability, flexibility, etc.

The second rubber resin is not particularly limited as long as it is a rubber resin that has fluidity at temperatures between -1°C and 40°C. For example, liquid butyl rubber, olefin-based liquid rubber, urethane-based liquid rubber, silicone-based liquid rubber, fluorine-based liquid rubber, etc. can be used, but liquid butyl rubber resin is preferable. Furthermore, the Shore hardness of the second rubber resin is preferably 25 to 35 at 25°C, type A, as determined by the method specified in ASTM D2240.

The content ratio of the first rubber resin to the second rubber resin is 8:2 to 4:6 by mass, and preferably 6:4 to 4:6.

[Tackifier]
The tackifier is a component that imparts a function of enhancing the initial adhesion of the functional adhesive composition. The tackifier is not particularly limited, and styrene-based resins, xylene-based resins, aromatic modified terpene resins, terpene phenol resins, aliphatic petroleum resins, aromatic petroleum resins, aliphatic aromatic petroleum resins, coumarone-indene resins, phenol-based resins, disproportionated rosin resins, rosin-modified phenol resins, etc. can be used. The content of the tackifier is 5 to 15 parts by mass, more preferably 8 to 12 parts by mass, relative to 100 parts by mass of the total mass of the first rubber resin and the second rubber resin. If the content is less than 5 parts by mass, the desired adhesive strength tends not to be exhibited, and if the content is more than 15 parts by mass, the initial adhesiveness tends to decrease when used under low temperature conditions.

[Materials that can be heated by external stimuli]
The functional adhesive composition preferably further contains a material that can be heated by an external stimulus. This allows a relatively simple heating method, such as electromagnetic induction heating or microwave heating, to be adopted as a heating method for the functional adhesive film. This allows the functional adhesive film to be easily heated to reduce the adhesive strength of the functional adhesive film, and the functional adhesive film can be peeled off from the cement-based structure without leaving any residue (glue residue).

The material capable of being heated by the external stimulus is not particularly limited, but examples include materials capable of being heated by electromagnetic induction and materials capable of being heated by microwaves. Among these, materials capable of being heated by electromagnetic induction are particularly preferred. Electromagnetic induction heating is a direct heating method that utilizes electromagnetic induction, and it is possible to selectively heat only the material to be heated. In addition, the material capable of being heated by the external stimulus is preferably in the form of a powder, so that it is ultimately uniformly incorporated into the functional adhesive composition.

The electromagnetic induction heating generates heat by passing an electric current through the object to be heated by electromagnetic induction, so the object to be heated must be an electrical conductor. Therefore, the material capable of electromagnetic induction heating is composed of an electrical conductor. Metallic materials, conductive non-metallic materials, etc. can be used as the conductor. Preferred metallic materials include aluminum, iron, copper, silver, gold, nickel, platinum, zinc, lead, stainless steel, etc., and preferred conductive non-metallic materials include carbon black, carbon fiber, graphene, etc.

The microwave heating described above generates heat through molecular motion and ionic conduction of the heated object by the action of electromagnetic waves of 5 to 40 KHz, so it is possible to heat dielectric, conductive and magnetic materials, but in reality it is mainly suitable for heating dielectric materials. Examples of the dielectric material that can be used include various synthetic resins; ceramics such as silicon carbide and silicon nitride; and mica. Examples of the conductive material that can be used include metal materials and conductive nonmetallic materials similar to the materials that can be heated by electromagnetic induction described above. Examples of the magnetic material that can be used include iron oxide and various ferrite materials.

The content of the material capable of being heated by an external stimulus in the functional adhesive composition is not particularly limited as long as it is an amount that can heat the side chain crystallized polymer to a temperature of 50°C or higher, but may be, for example, 1 to 20 parts by mass per 100 parts by mass of the total mass of the first rubber-based resin and the second rubber-based resin.

(Functional adhesive film)
An embodiment of the functional adhesive film disclosed in the present application will be described. The functional adhesive film of this embodiment includes a substrate, an adhesive layer, and a functional adhesive layer in this order, the adhesive layer includes an adhesive, and the functional adhesive layer includes the functional adhesive composition of the above embodiment.

The functional adhesive film contains the functional adhesive composition described above in its functional adhesive layer, so that it can maintain adhesion for a long period of time even when pressed against a cement-based structure with a smaller pressure than before. Specifically, the adhesive strength of the adhesive layer after pressing against a cement-based structure with a surface roughness Ra of 100 μm or less by 10 reciprocations using a 500 g roller can be 180° peel force measured in accordance with the provisions of JIS Z0237, and can be 1 N/10 mm or more when a sample cooled to a temperature of -1°C is measured, and 3 N/10 mm or more when measured in an environment of a temperature of 23°C and a relative humidity of 50%.

In addition, since the functional adhesive film contains the functional adhesive composition described above in its functional adhesive layer, the adhesive strength of the functional adhesive film can be reduced by heating the functional adhesive film to 50°C or higher, and the functional adhesive film can be peeled off from the cement-based structure without leaving any adhesive layer residue (glue residue) on the cement-based structure side. Specifically, the adhesive strength of the adhesive layer side after pressing it back and forth 10 times using a 500g roller against a cement-based structure with a surface roughness Ra of 100μm or less can be 1N/10mm or less as a 180° peel force measured in accordance with the provisions of JIS Z0237, when measured in an environment with a temperature of 60°C and a relative humidity of 5% or less. By heating the functional adhesive film to 50°C or higher, the adhesive strength can be reduced, and the film can be easily peeled off without leaving any adhesive residue as needed.

In addition, the functional adhesive film contains an adhesive in its adhesive layer, so that it can conform to uneven surfaces such as cement-based structures, can reliably bond the functional adhesive film to the cement-based structure, and can block contact between the outside air and the cement-based structure over a wide temperature range. This makes it possible to suppress the intrusion of rainwater and _CO2 through deteriorated parts such as cracks in the cement-based structure, and to prevent salt damage and alkali-aggregate reaction in the cement-based structure. Even if reinforcing bars or the like are present in the cement-based structure, corrosion of the reinforcing bars or the like can be prevented, and protective performance against cracked cement-based structures can be ensured.

Furthermore, because the functional adhesive film has a substrate, the color of the substrate can be adjusted in various ways to allow an inspector to apply the film in a simple manner immediately after inspection without compromising the aesthetic appearance of the film when applied to a cement-based structure, and the film can be easily peeled off when necessary without leaving any adhesive residue, making it possible to prevent deterioration of the cement-based structure caused by cracks.

The functional adhesive film is usually in contact with the substrate and the adhesive layer, and in contact with the adhesive layer and the functional adhesive layer.

In this application, cement-based structures include concrete structures and mortar structures.

Below, we will explain each component of the functional adhesive film of this embodiment.

(Functional adhesive layer)
The functional adhesive layer used in the functional adhesive film of this embodiment is intended to impart a function of reducing the adhesive strength of the functional adhesive film when the functional adhesive film is heated at 50° C. or higher. Specifically, the functional adhesive layer can impart a function of making the adhesive strength of the adhesive layer side after pressing the functional adhesive film against a cement-based structure having a surface roughness Ra of 100 μm or less by 10 reciprocations using a 500 g roller, to 1 N/10 mm or less when the functional adhesive film is measured in an environment at a temperature of 60° C. and a relative humidity of 5% or less, as a 180° peel strength measured in accordance with the provisions of JIS Z0237.

As described above, the functional adhesive layer is composed of a functional adhesive composition that includes a side chain crystallized polymer, a first rubber-based resin that does not have fluidity at temperatures between -1°C and 40°C, a second rubber-based resin that has fluidity at temperatures between -1°C and 40°C, and a tackifier.

The reason why the adhesive strength decreases when such a side chain crystallized polymer is used and the temperature is raised to 50°C is unclear, but it is believed to be as follows. That is, the side chain crystallized polymer has low adhesive strength, and normally, when the temperature of the side chain crystallized polymer is lower than the polymer melting point measured by differential scanning calorimetry, it exists in a state buried in other resin components of the functional adhesive layer. However, when the temperature of the side chain crystallized polymer increases, the viscosity of the side chain crystallized polymer decreases, and the side chain crystallized polymer with a small molecular weight migrates to the interface between the adherend and the functional adhesive layer, which is thought to result in a decrease in the adhesive strength of the functional adhesive film.

The thickness of the functional adhesive layer is not particularly limited, but is usually set to 5 to 20 μm. If the thickness of the functional adhesive layer is within the above range, the adhesive strength of the adhesive layer side after pressing it against the aforementioned cement-based structure having a surface roughness Ra of 100 μm or less by 10 reciprocations using a 500 g roller can be measured in an environment with a temperature of 60° C. and a relative humidity of 5% or less, as a 180° peel strength measured in accordance with the provisions of JIS Z0237, to be 1 N/10 mm or less.

(Adhesive layer)
The adhesive layer used in the functional adhesive film of this embodiment is intended to impart the inherent adhesive strength to the functional adhesive film, and more specifically, is provided so that the adhesive strength of the adhesive layer side of the functional adhesive film against a cement-based structure having a surface roughness Ra of 100 μm or less is 1 N/10 mm or more when a sample cooled to a temperature of -1°C is measured in accordance with the provisions of JIS Z0237 as a 180° peel force, and is 6 N/10 mm or more when measured in an environment at a temperature of 23°C and a relative humidity of 50%.

The adhesive contains at least one adhesive component selected from the group consisting of natural rubber adhesive components, synthetic rubber adhesive components, silicone adhesive components, acrylic adhesive components, and polyester adhesive components.

[Natural rubber adhesive component]
Examples of natural rubber adhesive components include cis-1,4-polypropylene rubber extracted only from the resin liquid of rubber trees (Hevea brasiliensis).

[Synthetic rubber adhesive component]
Examples of synthetic rubber adhesive components include styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, butyl rubber, ethylene-propylene rubber, and ethylene-propylene-diene rubber.

[Silicone-based adhesive component]
Examples of the silicone adhesive component include an addition reaction type silicone adhesive component and a peroxide curing type silicone adhesive component, and these may be used alone or in combination.

The above-mentioned addition reaction type silicone adhesive component is not particularly limited, but examples thereof include KR3700, KR3701, X-40-3237-1, X-40-3240, X-40-3291-1, X-40-3229, X-40-3270, and X-40-3306 (all trade names) manufactured by Shin-Etsu Chemical Co., Ltd., TSR1512, TSR1516, and XR37-B9204 (all trade names) manufactured by Momentive Performance Materials, Inc., and SD4584, SD4585, SD4560, SD4570, SD4600PFC, and SD4593 (all trade names) manufactured by Dow Corning Toray Co., Ltd.

The above-mentioned addition reaction type silicone adhesive component is used together with a crosslinking agent, and the crosslinking agent is not particularly limited, but examples that can be used include X-92-122 (product name) manufactured by Shin-Etsu Chemical Co., Ltd., CR50 (product name) manufactured by Momentive Performance Materials, Inc., and BY24-741 (product name) manufactured by Dow Corning Toray Co., Ltd.

Examples of the peroxide-curing silicone adhesive component include KR100 and KR101-10 (all trade names) manufactured by Shin-Etsu Chemical Co., Ltd., YR3340, YR3286, PSA610-SM, and XR37-B6722 (all trade names) manufactured by Momentive Performance Materials, Inc., and SH4280 (trade name) manufactured by Dow Corning Toray Co., Ltd.

The above peroxide-curable silicone adhesive component is used together with a crosslinking agent, which is not particularly limited, but examples include benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1'-di-t-butylperoxy-3,3,5-trimethylenecyclohexane, 1,3-di-(t-butylperoxy)-diisopropylbenzene, etc.

[Acrylic adhesive component]
Examples of the acrylic adhesive component include those obtained by copolymerizing (meth)acrylic acid ester monomers. Examples of the (meth)acrylic acid ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, etc. In addition, monomers containing functional groups such as (meth)acrylic acid, crotonic acid, fumaric acid, itaconic acid, and (anhydrous) maleic acid, vinyl acetate, acrylonitrile, styrene, 2-hydroxyethyl (meth)acrylate, and 2-methylolethylacrylamide may be added to the (meth)acrylic acid ester monomers to copolymerize them.

[Polyester-based adhesive component]
Examples of polyester-based adhesive components include those obtained by polycondensing polyvalent carboxylic acids (e.g., dicarboxylic acids) and polyalcohols (e.g., diols). Examples of the dicarboxylic acids include adipic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenyl succinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, citraconic acid, and other aliphatic and alicyclic dicarboxylic acids, as well as terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid. Examples of the diol include aliphatic glycols such as ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,5-pentanediol, 2-ethyl-2-butylpropanediol, 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, 1,4-cyclohexanedimethanol, and 1,2-cyclohexanedimethanol.

The adhesive preferably contains a crosslinking agent in addition to the adhesive component, and may further contain a crosslinking accelerator, a filler, a softener, a tackifier, an anti-aging agent, etc., as necessary.

[Crosslinking agent]
As the crosslinking agent, sulfur and thiuram-based agents such as tetramethylthiuram sulfide (TMTD), dipentamethylenethiuram tetrasulfide (DPTT), and p-quinone dioxime are generally used, with TMTD being the most preferred.

The amount of the crosslinking agent added must be at least 0.05 parts by mass per 100 parts by mass of the adhesive component, and is preferably 0.1 to 10 parts by mass. If the amount added is less than 0.05 parts by mass, the degree of crosslinking will be low, and the crosslinking process during preparation of the adhesive will tend to take a long time. In addition, the cohesive strength of the adhesive component will decrease, and adhesive residue will tend to remain on the adherend when the functional adhesive film is peeled off. On the other hand, if the amount added exceeds 10 parts by mass, the degree of crosslinking will be too high, and the initial kneading-off time will tend to be long.

[Crosslinking accelerator]
As the crosslinking accelerator, a thiuram-based, thiazole-based, or dithiocarbamate salt is used, and these may be used in combination. The amount of the crosslinking accelerator is determined based on the type and amount of the crosslinking agent per 100 parts by mass of the adhesive component, and therefore it is usually preferable to use the accelerator in the range of 2 to 10 parts by mass.

[Filler]
The filler is used to give the adhesive a desired color and also to enhance the reinforcing properties of the adhesive component. As the filler, calcium carbonate, titanium oxide, clay, silica, talc, carbon black, etc. can be used, but it is particularly preferable to use calcium carbonate or titanium oxide. The fillers may be used in combination of two or more kinds.

The amount of the filler added must be at least 60 parts by mass per 100 parts by mass of the adhesive component, and is preferably 70 to 250 parts by mass. If the amount added is less than 60 parts by mass, the cohesive strength of the adhesive component decreases, and if it exceeds 250 parts by mass, the rubber elasticity is poor and the Mooney viscosity becomes too high, making it unsuitable as a raw material for the adhesive.

[Softener]
The softener is usually used together with the filler, and process oil, liquid polybutene, liquid polybutadiene, etc. can be used as the softener, but it is preferable to use process oil because the effect of the adhesive layer can be obtained more favorably. The amount of the softener added must be at least 30 parts by mass or more relative to 100 parts by mass of the adhesive component, and is preferably 30 to 400 parts by mass. If the amount added is less than 30 parts by mass, the adhesive component and the filler are difficult to be homogenized, resulting in poor processability, and if the amount added is more than 400 parts by mass, the Mooney viscosity tends to be too low.

[Tackifier]
The tackifier is not particularly limited, and examples thereof include styrene-based resins, xylene-based resins, aromatic modified terpene resins, terpene phenol resins, aliphatic petroleum resins, aromatic petroleum resins, aliphatic aromatic petroleum resins, coumarone-indene resins, phenol-based resins, disproportionated rosin resins, and rosin modified phenol resins. The amount of the tackifier added is preferably 15 to 70 parts by mass relative to 100 parts by mass of the adhesive component. If the amount added is less than 15 parts by mass, the desired adhesive strength tends not to be achieved, and if the amount added is more than 70 parts by mass, the initial adhesiveness tends to decrease when used under low temperature conditions.

[Anti-aging agent]
Addition of an antiaging agent is effective for improving the aging resistance of the adhesive constituting the above-mentioned adhesive layer.As the above-mentioned antiaging agent, for example, phenol-based, amine-based, benzimidazole-based, sulfur-based, and phosphorus-based antiaging agents can be used, but are not particularly limited thereto.Among these, it is preferable to use phenol-based and sulfur-based antiaging agents.These antiaging agents may be used alone or in combination of two or more.

The main cause of adhesive aging is the oxidative deterioration of the adhesive components that make up the adhesive. Anti-aging agents are classified according to the mechanism by which they inhibit the oxidative deterioration of the adhesive components, and are divided into radical chain inhibiting and peroxide decomposing types.

The above radical chain inhibiting antioxidants have phenolic "-OH" or "-NH" in the molecule, which are prone to react with radicals. They react with radicals generated in the polymer due to deterioration, inactivating them and thereby stopping autoxidation. Phenol-based and amine-based antioxidants are radical chain inhibiting.

On the other hand, peroxide decomposition type antioxidants are typically compounds containing sulfur or phosphorus, or benzimidazole-based compounds, which decompose the hydroperoxide (ROOH) generated in the polymer and convert it into a stable substance (ROH, etc.).

When considering coloring the adhesive in any color, a non-staining phenol-based anti-aging agent is preferable as the anti-aging agent. The amount of the anti-aging agent added is preferably 2 to 10 parts by mass per 100 parts by mass of the adhesive component. If the amount added is less than 2 parts by mass, the adhesive tends to deteriorate, and even if the amount added exceeds 10 parts by mass, there is no significant change in the effect of adding the agent.

The thickness of the adhesive layer can be determined depending on the ability to conform to the uneven surface of the cement-based structure, and is not particularly limited, but is preferably 200 to 5000 μm, and more preferably 300 to 800 μm. If the thickness of the adhesive layer is less than 200 μm, it will tend not to conform to the unevenness of the cracked surface of the cement-based structure, and will tend not to achieve a 180° peel force of 3 N/10 mm measured in accordance with the JIS Z0237 standard at a temperature of 23° C. and a relative humidity of 50%. On the other hand, even if the thickness of the adhesive layer exceeds 5000 μm, there will be no significant change in the ability to conform to the unevenness of the cracked surface, but there will be a tendency for adhesive residue to be left on the cement-based structure when peeled off.

The adhesive layer may further contain the material capable of being heated by an external stimulus as described above. The content of the material capable of being heated by an external stimulus in the adhesive layer is not particularly limited as long as it is an amount that can heat the side chain crystallized polymer contained in the functional adhesive layer of the functional adhesive film to a temperature of 50°C or higher, but may be, for example, 1 to 20 parts by mass per 100 parts by mass of the adhesive component.

(Substrate)
The substrate used in the functional adhesive film of this embodiment serves as the functional adhesive layer and a base on which the adhesive layer is formed.

Examples of the substrate include resin substrates, and specific examples of the resin substrates include polyolefin resins (low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, very low density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolypropylene, polybutene, polymethylpentene, etc.), ethylene-vinyl acetate copolymers, ionomer resins, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, polyurethane resins, polyester resins (polyethylene Examples of the base material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), etc.), polyimide resin, polyamide resin, polyether ketone resin, polyether resin, polyether sulfone resin, polystyrene resin (polystyrene, etc.), polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polycarbonate resin, fluorine resin, silicone resin, cellulose resin, and crosslinked bodies of these resins. Among these, polyethylene terephthalate (PET) is more preferable in terms of mechanical properties and cost. One or more of these constituent materials can be used. In addition, the above-mentioned constituent materials may have a functional group as necessary. In addition, functional monomers or modifying monomers may be grafted to the constituent materials.

The surface of the substrate may be subjected to a known surface treatment in order to improve adhesion with the adjacent adhesive layer. Specific examples of the surface treatment include corona discharge treatment, ozone exposure treatment, high-voltage shock exposure treatment, and ionizing radiation treatment. The substrate may also be subjected to a coating treatment with an undercoat agent (such as silicone treatment), a primer treatment, a matte treatment, a crosslinking treatment, etc.

The substrate may be in the form of a single layer or a laminate of two or more layers. If necessary, known auxiliary agents such as fillers, flame retardants, antidegradants, antistatic agents, softeners, UV absorbers, antioxidants, plasticizers, and surfactants may be added to the substrate.

The thickness of the substrate is not particularly limited, but is preferably 30 to 300 μm, and more preferably 50 to 150 μm. If the thickness of the substrate is less than 30 μm, the strength of the functional adhesive film of this embodiment itself tends to be insufficient, and if it exceeds 300 μm, the cost becomes high.

(Resin Layer)
In order to ensure the weather resistance and chemical resistance of the substrate, it is preferable to dispose a resin layer on the main surface of the substrate opposite to the main surface on which the functional adhesive layer and the adhesive layer are formed. The resin constituting the resin layer is preferably a fluorine-based resin or a silicone-based resin.

Next, a method for producing the functional adhesive film of the present embodiment will be described. The method for producing the functional adhesive film of the present embodiment is not particularly limited, but the film can be produced, for example, by combining the following steps.
(1) A step of preparing the above-mentioned substrate, an adhesive layer-forming paint containing the components of the above-mentioned adhesive layer, and a functional adhesive layer-forming paint containing the components of the above-mentioned functional adhesive layer. (2) A step of applying the above-mentioned adhesive layer-forming paint to one side of the above-mentioned substrate to prepare an adhesive layer, and then laminating a release film onto the adhesive layer. (3) A step of applying the above-mentioned functional adhesive layer-forming paint to another release film to prepare a functional adhesive layer with a release film. (4) A step of laminating the functional adhesive layer side of the above-mentioned functional adhesive layer with a release film to the above-mentioned adhesive layer while peeling off the release film of the above-mentioned adhesive layer.

The functional adhesive film produced by the above process is used by removing the release film from the functional adhesive layer.

Next, the functional adhesive film of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the functional adhesive film of this embodiment. In FIG. 1, the functional adhesive film 10 has an adhesive layer 12 on a substrate 11, and a functional adhesive layer 13 on the adhesive layer 12. FIG. 2 is a schematic cross-sectional view showing another example of the functional adhesive film of this embodiment. In FIG. 2, the functional adhesive film 20 has an adhesive layer 12 on a substrate 11, and a functional adhesive layer 13 on the adhesive layer 12, and further has a release sheet 14 on the functional adhesive layer 13.

The functional adhesive film of the present embodiment preferably has a carbon dioxide permeability of 0.5 g/( ^m2 ·24 hr·1 atm) or less at 20° C. as specified in JIS K7126. If the carbon dioxide permeability is within the above range, it is possible to block not only carbon dioxide, which accelerates the deterioration of cement-based structures, but also chloride ions, water, oxygen, and the like, which accelerate the deterioration of cement-based structures.

(How to use the functional adhesive film)
An embodiment of the method for using the functional adhesive film disclosed in the present application will be described. The method for using the functional adhesive film of this embodiment includes the steps of preparing the functional adhesive film of the above embodiment, attaching the functional adhesive layer side of the functional adhesive film to a deteriorated part of a cement-based structure and then pressing the functional adhesive film with a predetermined pressure, leaving the cement-based structure to which the functional adhesive film is attached and pressed in a natural environment for a certain period of time, heating the functional adhesive film after leaving the functional adhesive film to reduce the adhesive strength of the functional adhesive film, and peeling off the functional adhesive film with reduced adhesive strength from the cement-based structure.

In addition, in the method of using the functional adhesive film, the above-mentioned pressure-bonding can be performed by using a 500g roller and moving it back and forth 10 times.

According to the method of using the functional adhesive film of this embodiment, the functional adhesive film can be easily attached to the deteriorated part of the cement-based structure at room temperature immediately after inspecting the cement-based structure, and the adhesion can be reliably maintained, and the film can be easily peeled off without leaving any adhesive residue by heating as necessary. In addition, while the functional adhesive film is attached to the deteriorated part of the cement-based structure, deterioration of the cement-based structure can be prevented, and since the durability and fatigue resistance of the functional adhesive film itself are high, deterioration of the cement-based structure can be prevented for a long period of time. Furthermore, since the adhesive layer of the functional adhesive film can be colored, the color of the functional adhesive film itself can be matched to the color of the cement-based structure, and therefore the aesthetics are not impaired even when the functional adhesive film is attached to the cement-based structure.

In addition, the functional adhesive film used in this embodiment contains an adhesive in its adhesive layer, so that it can conform to uneven surfaces such as the surface of a cement-based structure, can block contact between the outside air and the cement-based structure over a wide temperature range, can suppress the intrusion of rainwater and _CO2 through deteriorated parts such as cracks in the cement-based structure, and can prevent salt damage and alkali-aggregate reaction in the cement-based structure. Even if reinforcing bars or the like are present in the cement-based structure, the corrosion of the reinforcing bars or the like can be prevented, and protective performance for cracked cement-based structures can be ensured.

In addition, since the functional adhesive layer of the functional adhesive film contains a side chain crystallized polymer, the adhesive strength of the functional adhesive film can be reduced by heating the functional adhesive film at a temperature of 50°C or higher, which is the temperature of the side chain crystallized polymer, and the functional adhesive film can be peeled off from the cement-based structure without leaving any residue of the adhesive layer (glue residue) on the cement-based structure. This makes it easy to visually check the size of deteriorated areas such as cracks in the cement-based structure, and it can be determined whether or not full-scale repair work is necessary at that point (usually five years after the previous inspection). Generally, if the deterioration (cracks) of the cement-based structure has progressed significantly at this point, repair work is carried out, and if the deterioration of the cement-based structure has not progressed, a follow-up observation is carried out for another five years.

Furthermore, the functional adhesive film used in this embodiment can maintain adhesion for a long period of time even when pressed against a cement-based structure with a small pressure, such as 10 reciprocating strokes using a 500 g roller.

Next, a method of using the functional adhesive film of this embodiment will be described with reference to the drawings. In the following method of using the functional adhesive film, an example will be described in which a concrete structure is used as a cement-based structure. First, as shown in FIG. 3, the functional adhesive layer 13 side of the functional adhesive film 10 of this embodiment shown in FIG. 1 described above is attached to the crack 16 of the concrete 15. Then, the functional adhesive film 10 is pressed against the substrate 11 side with a predetermined pressure.

In the state shown in Figure 3, the concrete is left for a certain period of time until the next inspection. During this period, for example, five years, the cracks 16 in the concrete 15 are covered with the functional adhesive film 10, so the deterioration of the concrete does not progress any further or the progress of the deterioration is slowed down.

Next, at the time of the next inspection, for example, five years later, as shown in FIG. 4, heat 17 is applied to the functional adhesive film 10, for example, to heat the functional adhesive film 10 to 50 to 60°C. At this time, since the functional adhesive layer 13 of the functional adhesive film 10 contains the above-mentioned side chain crystallized polymer, the adhesive strength of the functional adhesive film 10 decreases during the above heating. Therefore, even if the functional adhesive film 10 is subsequently peeled off from the concrete 15, as shown in FIG. 5, no adhesive residue of the adhesive layer is left on the surface of the concrete 15. This makes it easy to check the deterioration state of the concrete. After that, the overall deterioration state of the concrete structure is examined, focusing on the size and depth of the cracks 16 in the concrete 15, and a repair plan for the future is created. For example, if the cracks 16 have significantly expanded compared to five years ago when the functional adhesive film 10 was attached, a repair plan can be made immediately.

The above process provides a simple method for preventing deterioration of concrete and determining whether or not a concrete structure needs repair.

In the above process, an example is shown in which the functional adhesive film 10 shown in FIG. 1 is used. However, if the functional adhesive film 20 shown in FIG. 2 is used, the release sheet 14 is peeled off, and then the functional adhesive layer 13 side of the functional adhesive film 20 is attached to the concrete.

Figure 6 is a schematic cross-sectional view showing an example of a state in which a conventional adhesive film has been peeled off from a crack in concrete. Conventional adhesive films do not have a functional adhesive layer containing a side-chain crystallized polymer, so when peeled off at room temperature or even when peeled off by heating, as shown in Figure 6, adhesive residue 12a of the adhesive layer is likely to remain on the surface of concrete 15.

The functional adhesive film disclosed in this application will be described in detail below with reference to examples. However, the following examples do not limit the functional adhesive film disclosed in this application. In addition, "parts" in the examples refers to "parts by mass."

Example 1
<Preparation of functional adhesive layer forming paint>
First, the materials shown below were thoroughly dissolved and mixed in a mixer to prepare a functional adhesive layer-forming coating material.
(1) Solid butyl rubber (first rubber resin: butyl rubber not having flowability at temperatures of -1°C to 40°C, manufactured by LANXESS, trade name "X_Butyl RB301", Shore hardness at 24.4°C: 72): 70 parts (2) Liquid butyl rubber (second rubber resin: butyl rubber having flowability at temperatures of -1°C to 40°C, manufactured by Shinko Trading Co., Ltd., trade name "Karen 800", Shore hardness at 24.4°C: 32): 30 parts (3) Behenyl acrylate (carbon number: 25) / acrylic acid copolymer (side chain crystallized polymer, weight average molecular weight: 7500): 10 parts (4) Tackifier (alicyclic saturated hydrocarbon resin, manufactured by Arakawa Chemical Co., Ltd., trade name "Alcon P125"): 10 parts (5) Toluene: 480 parts

<Preparation of adhesive layer forming paint>
Next, the materials shown below were thoroughly kneaded in a kneader to prepare an adhesive layer-forming paint (butyl rubber-based adhesive).
(1) Partially crosslinked butyl rubber (manufactured by Shinko Trading Co., Ltd., trade name "Kohler 5215A"): 100 parts (2) Crosslinking agent (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Vulnoc GM"): 0.1 parts (3) Filler (calcium carbonate): 209.4 parts (4) Softener (process oil): 386.6 parts (5) Tackifier (C5 resin, manufactured by Nippon Zeon Co., Ltd., trade name "Quinton A100"): 21.8 parts

<Preparation of functional adhesive film>
First, the above-mentioned adhesive layer-forming paint was applied to one side of a base PET film (manufactured by Toray Industries, Inc., product name "S-10", thickness: 50 μm) using a calendar to form an adhesive layer to a thickness of 600 μm, and then a release PET film (manufactured by Nakamoto Pax Co., Ltd., product name "NS-50-ZW", thickness: 50 μm) was bonded onto the adhesive layer at a nip pressure of 0.5 MPa to produce an adhesive layer laminate consisting of base PET film/adhesive layer/release PET film.

Next, the functional adhesive layer-forming paint was applied to one side of a release PET film (manufactured by Nakamoto Pax, product name "NS-50-ZW", thickness: 50 μm) and dried at 110°C for 5 minutes to form a functional adhesive layer laminate with a functional adhesive layer that was 7 μm thick after drying.

Next, while peeling off the release PET film from the functional adhesive layer laminate, the functional adhesive layer side of the functional adhesive layer laminate was attached to the adhesive layer at a nip pressure of 0.5 MPa to produce the functional adhesive film of Example 1.

Example 2
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 60 parts and the amount of liquid butyl rubber was changed to 40 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and a functional adhesive film of Example 2 was prepared in the same manner as in Example 1.

Example 3
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 40 parts and the amount of liquid butyl rubber was changed to 60 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and the functional adhesive film of Example 3 was prepared in the same manner as in Example 1.

Example 4
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 60 parts, the amount of liquid butyl rubber was changed to 40 parts, and the amount of behenyl acrylate was changed to 5 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and the functional adhesive film of Example 4 was prepared in the same manner as in Example 1.

Example 5
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 60 parts, the amount of liquid butyl rubber was changed to 40 parts, and the amount of behenyl acrylate was changed to 20 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and the functional adhesive film of Example 5 was prepared in the same manner as in Example 1.

Example 6
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 60 parts, the amount of liquid butyl rubber was changed to 40 parts, and the amount of tackifier was changed to 5 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and the functional adhesive film of Example 6 was prepared in the same manner as in Example 1.

(Example 7)
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 60 parts, the amount of liquid butyl rubber was changed to 40 parts, and the amount of tackifier was changed to 15 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and the functional adhesive film of Example 7 was prepared in the same manner as in Example 1.

(Comparative Example 1)
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 100 parts and no liquid butyl rubber was added.A functional adhesive film of Comparative Example 1 was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used.

(Comparative Example 2)
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 30 parts and the amount of liquid butyl rubber was changed to 70 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and a functional adhesive film of Comparative Example 2 was prepared in the same manner as in Example 1.

(Comparative Example 3)
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 60 parts, the amount of liquid butyl rubber was changed to 40 parts, and behenyl acrylate was not added.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and a functional adhesive film of Comparative Example 3 was prepared in the same manner as in Example 1.

(Comparative Example 4)
A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that the amount of solid butyl rubber was changed to 60 parts, the amount of liquid butyl rubber was changed to 40 parts, and the amount of behenyl acrylate was changed to 40 parts.A functional adhesive layer forming paint was prepared in the same manner as in Example 1, except that this functional adhesive layer forming paint was used, and a functional adhesive film of Comparative Example 4 was prepared in the same manner as in Example 1.

Next, the adhesive strength of the functional adhesive films produced in Examples 1 to 7 and Comparative Examples 1 to 4 above was evaluated as follows.

<Adhesion to mortar>
First, 33 mortar plates (150 mm x 70 mm x 10 mm) manufactured by Engineering Test Services were prepared, and the surface roughness Ra of three arbitrary points on the adhesion surface of each mortar plate was measured using a laser microscope "VK-9710" manufactured by Keyence Corp. As a result, the surface roughness Ra of each measurement point of all mortar plates was within the range of 15.3 to 84.3 μm (all less than 100 μm).

Next, of the 33 mortar plates prepared, three each were assigned to the adherends of Examples 1 to 7 and Comparative Examples 1 to 4.

Next, the release PET film was peeled off from the functional adhesive film, and the functional adhesive layer side of the functional adhesive film was attached to the adherend surface of the mortar board, and a 500g roller was used to roll it back and forth 10 times to produce a measurement sample. Next, the measurement sample was cooled to a temperature of -1°C and the adhesive strength (180° peel strength) was measured in accordance with the provisions of JIS Z0237. In addition, another measurement sample prepared in the same manner was placed in a thermostatic chamber set to a temperature of 23°C and a relative humidity of 50%, and the adhesive strength (180° peel strength) was measured in accordance with the provisions of JIS Z0237. In addition, another measurement sample prepared in the same manner was placed in a thermostatic chamber set to a temperature of 60°C and a relative humidity of 5%, and the adhesive strength (180° peel strength) was measured in accordance with the provisions of JIS Z0237.

<Adhesion to concrete>
First, a concrete plate (150 mm x 70 mm x 10 mm) was prepared according to the method for preparing a test substrate described in the Weather Resistance Test Method for Surface Coating Materials (JSCE-K 511-2018) of the Japan Society of Civil Engineers' Standard Specifications for Concrete (Standards Edition), and the surface roughness Ra of any three points on the adhesion surface of the concrete plate was measured using a laser microscope "VK-9710" manufactured by Keyence Corporation. As a result, the surface roughness Ra of each measurement point of the concrete plate was within the range of 24.7 to 84.2 μm (all 100 μm or less).

Next, in the same manner as in the case of the mortar board, the adhesive strength of the functional adhesive film of Example 1 against the concrete board was measured at temperatures of -1°C, 23°C, and 60°C.

Finally, after measuring the adhesive strength of all the samples, the adherend surfaces of the mortar board and concrete board were observed after the functional adhesive film was completely peeled off to check whether any adhesive residue remained.

The above results are shown in Tables 1 and 2.

In Tables 1 to 4, "no" adhesive residue means that no adhesive residue was observed on the adherend surface, and "partial" adhesive residue means that adhesive residue was observed on part of the adherend surface.

From Table 1 using mortar boards, it can be seen that the functional adhesive films of Examples 1 to 7 had high adhesiveness, with an adhesive strength of 1 N/10 mm or more at -1°C and an adhesive strength of 3 N/10 mm or more at 23°C. Furthermore, the adhesive strength of Examples 1 to 7 after heating to 60°C decreased to less than 1 N/10 mm, and the adhesive tape could be peeled off without leaving any glue residue after heating.

In addition, from Table 2, which used a concrete board, it can be seen that the adhesive strength of the functional adhesive film of Example 1 to a concrete board was similar to that to a mortar board.

On the other hand, the functional adhesive films of Comparative Example 1 and Comparative Example 3 had higher adhesive strength at 60°C than Examples 1 to 7, and were difficult to peel off. The functional adhesive film of Comparative Example 2 had an adhesive strength at 23°C of less than 3N/10mm, and had reduced adhesiveness at room temperature. Furthermore, the functional adhesive film of Comparative Example 4 had an adhesive strength at -1°C of less than 1N/10mm, and an adhesive strength at 23°C of less than 3N/10mm, and had reduced adhesiveness at low and room temperatures.

The functional adhesive film disclosed in this application is capable of preventing deterioration of cement-based structures in a simple manner, and can be widely used as a functional adhesive film that can maintain adhesion for a long period of time even when applied to cement-based structures with a smaller pressure, making it particularly useful in the fields of civil engineering and construction.

REFERENCE SIGNS LIST 10, 20 Functional adhesive film 11 Substrate 12 Adhesive layer 13 Functional adhesive layer 12a Adhesive residue 14 Release sheet 15 Concrete 16 Cracked portion 17 Heat

Claims (15)

A functional adhesive composition comprising a side-chain crystallized polymer, a first rubber-based resin having no fluidity at temperatures of -1°C to 40°C, a second rubber-based resin having fluidity at temperatures of -1°C to 40°C, and a tackifier,
A content ratio of the first rubber resin to the second rubber resin is 8:2 to 4:6 in terms of mass ratio,
the content of the side chain crystallized polymer is 1 to 20 parts by mass relative to 100 parts by mass of the total mass of the first rubber resin and the second rubber resin;
The functional adhesive composition has a tackifier content of 5 to 15 parts by mass per 100 parts by mass of the total mass of the first rubber resin and the second rubber resin. the side-chain crystallizing polymer is a copolymer of a linear acrylate having an alkane chain having 18 or more carbon atoms and an acrylic monomer having a solubility parameter of 7.3 to 9.5;
The functional adhesive composition according to claim 1, wherein the side chain crystallizable polymer has a weight average molecular weight of 1,000 to 15,000. The functional adhesive composition according to claim 1 or 2, wherein the endothermic peak of the side chain crystallized polymer measured by differential scanning calorimetry is 50°C or higher. The functional adhesive composition according to any one of claims 1 to 3, wherein the first rubber-based resin and the second rubber-based resin are both butyl rubber-based resins. The functional adhesive composition according to any one of claims 1 to 4, further comprising a material that can be heated by an external stimulus. The content of the material capable of being heated by an external stimulus is 1 to 20 parts by mass per 100 parts by mass of the total mass of the first rubber-based resin and the second rubber-based resin. The functional adhesive composition according to claim 5 or 6, wherein the material capable of being heated by an external stimulus is a material capable of being heated by electromagnetic induction or a material capable of being heated by microwaves. A functional adhesive film including a substrate, an adhesive layer, and a functional adhesive layer in this order,
The adhesive layer includes an adhesive,
The functional adhesive film, wherein the functional adhesive layer comprises the functional adhesive composition according to any one of claims 1 to 7. The functional adhesive film according to claim 8, in which the adhesive strength of the adhesive layer side after pressing against a cement-based structure having a surface roughness Ra of 100 μm or less by rolling the roller back and forth 10 times using a 500 g roller is 180° peel force measured in accordance with the provisions of JIS Z0237, and is 1 N/10 mm or more when a sample cooled to a temperature of -1°C is measured, 3 N/10 mm or more when measured in an environment at a temperature of 23°C and a relative humidity of 50%, and 1 N/10 mm or less when measured in an environment at a temperature of 60°C and a relative humidity of 5% or less. The functional adhesive film according to claim 8 or 9, wherein the thickness of the functional adhesive layer is 5 to 20 μm. The functional adhesive film according to any one of claims 8 to 10, wherein the thickness of the adhesive layer is 300 to 800 μm. The functional adhesive film according to any one of claims 8 to 11, wherein at least one selected from the adhesive layer and the functional adhesive layer contains a material that can be heated by an external stimulus. The functional adhesive film according to any one of claims 8 to 12, wherein the adhesive contained in the adhesive layer contains at least one adhesive component selected from the group consisting of a natural rubber adhesive component, a synthetic rubber adhesive component, a silicone adhesive component, an acrylic adhesive component, and a polyester adhesive component. A step of preparing a functional adhesive film according to any one of claims 8 to 13 ;
A step of attaching the functional adhesive layer side of the functional adhesive film to a deteriorated portion of a cement-based structure and then pressing the functional adhesive layer side to the deteriorated portion of the cement-based structure with a predetermined pressure;
A step of leaving the cement-based structure to which the functional adhesive film has been attached and pressure-bonded in a natural environment for a certain period of time;
After the standing, a step of heating the functional adhesive film to reduce the adhesive strength of the functional adhesive film;
and a step of peeling off the functional adhesive film whose adhesive strength has been reduced from the cement-based structure. The method for using the functional adhesive film according to claim 14, wherein the pressure bonding is performed by 10 reciprocating movements using a 500 g roller.