JP6787653B2 - A method for manufacturing an adhesive sheet that covers the surface of a cement-based material and a cement-based structure. - Google Patents

Description

The present disclosure relates to an adhesive sheet that covers the surface of a cement-based material, and a method for manufacturing a cement-based structure.

Cement-based materials such as concrete, mortar or cement are widely used in various structures such as buildings, roads, bridges, dams, tunnels and harbor facilities. In many cases, a cement-based structure composed of a cement-based material after curing is required to have excellent strength and its long-term retention (that is, durability). In order to impart such sufficient quality to the cement-based structure, it is important to cure it by maintaining an appropriate temperature, a wet state, etc. for the curing reaction. Curing requires a period of at least several days, generally one month or longer, preferably three months or longer for large structures, depending on the structure and weather conditions, and therefore cement-based over this period. Control of conditions such as material temperature and wet condition is required.

As a curing method of the cement-based material, a method of reducing the evaporation of water from the surface of the cast cement-based material, for example, sealing curing and coating film curing; water is applied to the surface of the cast cement-based material. Methods involving feeding, such as watering and flooding; methods involving holding a water-absorbent sheet facing the surface of the cast cement-based material, such as wet cloth curing; and casting. Examples thereof include a method including supplying water between the sheet and the surface of the cement-based material while holding the sheet facing the surface of the cement-based material, for example, water supply curing. These methods are not always clearly distinguished.

Patent Document 1 is an adhesive tape used during curing of concrete and covering the surface of concrete, and comprises at least a base material layer and an adhesive layer provided on one surface of the base material layer. Described is an adhesive tape for concrete curing, characterized in that the maximum load F obtained by the product of the tear strength TR and the thickness t of the base material layer is approximately 5 to 40 N.

Patent Document 2 is a curing sheet for concrete including a bubble layer and an adhesive layer laminated on the bubble layer, and the adhesive force between the adhesive layer and the bubble layer is such that the adhesive layer and the concrete to be adhered are placed. A curing sheet for concrete characterized in that the adhesive force generated between the surfaces is 80% or less and the adhesive force generated between the adhesive layer and the concrete casting surface is 0.15 N / cm ² or more. Describe.

JP-A-2002-255670 Japanese Unexamined Patent Publication No. 2014-37693

The techniques described in Patent Documents 1 and 2 are considered to contribute to a certain extent to the simple curing. However, when a cement-based material is cast using a formwork, it tends to be desired to remove the formwork as soon as possible due to restrictions on the work process, delivery time, and the like. Especially for the lining concrete of the inner wall of the tunnel, it is required to move the formwork as the tunnel pit is dug, and moving the formwork early leads to shortening the construction period. However, the cement-based material from which the mold was removed at an early stage has a high water content due to insufficient hydration reaction, and it is not possible to adhere a conventional adhesive sheet to such a cement-based material well. Have difficulty. Further, it is more difficult to obtain an adhesive sheet that can be adhered to a cement-based material having a high water content and can be easily peeled off and removed after the cement-based material is cured. Therefore, the adhesive for covering the cement-based material can be shortened and can be removed after use (that is, after the cement-based material is cured) without leaving an adhesive layer on the obtained cement-based structure. There is a request for a sheet.

The present invention solves the above-mentioned problems, shortens the construction period, and realizes a high-quality cement-based structure (for example, a concrete structure), an adhesive sheet for covering a cement-based material, and a cement-based structure using the same. The purpose is to provide a method for manufacturing a structure.

One aspect of the disclosure is
An adhesive sheet that covers the surface of cement-based materials.
It has a pressure-sensitive adhesive layer containing a polymer derived from a monomer component containing an alkyl (meth) acrylate having 4 to 18 carbon atoms and a monomer having at least one nitrogen-containing functional group.
Provided is an adhesive sheet in which the pressure-sensitive adhesive layer can be adhered to the surface of a wet cement-based material and can be peeled off from the surface of the cement-based material after curing.

Another aspect of the present disclosure provides a roll constructed by winding the adhesive sheet.

Another aspect of the disclosure is
It is a manufacturing method of cement-based structures.
Obtaining a cement-based material with an exposed surface,
When the exposed surface is in a wet state, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is attached to the exposed surface.
Hardening the cement-based material to obtain a cement-based structure, and removing the adhesive sheet from the cement-based structure.
Provide manufacturing methods including.

According to the adhesive sheet of the present disclosure, an adhesive sheet for covering a cement-based material, which can shorten the construction period and realize a high-quality cement-based structure, and a method for manufacturing a cement-based structure using the adhesive sheet are provided. To.

It is a figure which shows one aspect of the adhesive sheet of this disclosure.

Hereinafter, the present invention will be described in more detail with reference to the drawings for the purpose of exemplifying typical embodiments of the present invention, but the present invention is not limited to these embodiments and drawings. Unless otherwise specified, the various characteristic values of the present disclosure are intended to be values measured by a method described in the [Examples] section of the present disclosure or a method understood by those skilled in the art to be equivalent thereto. ..

The present disclosure is an adhesive sheet that covers the surface of a cement-based material, and is a polymer derived from a monomer component containing an alkyl (meth) acrylate having 4 to 18 carbon atoms and a monomer having at least one nitrogen-containing functional group. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the above, and the pressure-sensitive adhesive layer can be adhered to the surface of the cement-based material in a wet state and can be peeled off from the surface of the cement-based material after curing. provide. The present disclosure also provides a roll constructed by winding an adhesive sheet according to the present disclosure.

In the present disclosure, "concrete" is intended to include a mixture containing sand, gravel, water, cement, and optionally an admixture, and a cured product obtained by curing the mixture. Various types of concrete have been conventionally known, and in the present disclosure, they are appropriately selected according to the purpose. For example, concrete examples include general building concrete, cold concrete, hot concrete, mass concrete, fluidized concrete, high fluidity concrete, high strength concrete, low heat generation concrete, expansion concrete, prestressed concrete, low shrinkage concrete, and fiber reinforcement. Examples thereof include concrete, polymer concrete, watertight concrete, underwater concrete, water permeable / drainable concrete, resin impregnated concrete, shielding concrete, lightweight concrete, prepacked concrete, and sprayed concrete.

In the present disclosure, "mortar" is intended to include a mixture containing sand, water, cement, and optionally an admixture, and a cured product obtained by curing the mixture.

In the present disclosure, "cement" includes all powders that can be used in the production of concrete and mortar and that are cured by a hydration reaction or the like with water, a liquid agent, or the like, and a cured product obtained by curing the powder. Intended, it may be an organic substance, an inorganic substance, or a combination thereof. Cement includes general cement such as Portland cement, mixed cement, and alumina cement, as well as asphalt, glue, resin, gypsum, lime, and the like.

In the present disclosure, "cement-based material" is intended to be the material of the present disclosure, which is concrete, mortar or cement.

The pressure-sensitive adhesive sheets of the present disclosure are advantageous for concrete, mortar, and cement containing cement that hardens by hydration. In a typical embodiment, the components of the cement, silicate tricalcium (3CaO · SiO _2), dicalcium silicate (2CaO · SiO _2), tricalcium aluminate _{(3CaO · Al 2 O 2)} , iron aluminate tetracalcium _{(4CaO · Al 2 O 2 ·} Fe 2 O 3), gypsum (CaSO ₄ · 2H ₂ O) and the like, cement may comprise one or more of these.

In the present disclosure, the curing of cement-based materials means a certain period of time after the construction of cement-based materials (casting (driving), spraying, etc.) of cement-based materials in order to ensure the required quality of the cement-based materials. The process is intended to maintain the temperature and wet condition required for curing.

<Adhesive sheet>
The pressure-sensitive adhesive sheet of the present disclosure is used to cover the surface of a cement-based material. In the pressure-sensitive adhesive sheet of the present disclosure, the pressure-sensitive adhesive layer can be adhered to the surface of the cement-based material in a wet state, and can be peeled off from the surface of the cement-based material even after the cement-based material is cured. .. In the present disclosure, the wet state of the surface of a cement-based material is intended to be, for example, the state of the cement-based material when it is demolded the day after the cement-based material is placed. The adhesive layer can be adhered to the surface of a wet cement-based material, for example, when the adhesive sheet is attached to the surface of such a wet cement-based material such as a ceiling surface, the adhesive layer is peeled off by the weight of the sheet itself. Instead, it is intended that the adhesive sheet can be adhered to the cement-based material with a force stronger than the unwinding force when the roll-shaped sheet is pulled out when the adhesive sheet is attached. Further, the fact that the pressure-sensitive adhesive layer can be peeled off from the surface of the cement-based material after curing means that the pressure-sensitive adhesive layer can be peeled off from the surface of the cement-based material with little residue.

Generally, in the curing process of a cement-based material, the water content of the cement-based material decreases with time due to the consumption of water by the hydration reaction. For example, in the case of a cement-based material immediately after construction or only a relatively short time (for example, 8 to 15 hours) has passed since construction, the moisture content near the surface of the cement-based material is 4% or more with a concrete / mortar moisture meter. Depending on the case, 12% or more may be measured. The adhesive sheet of the present disclosure can be adhered to the surface of such a wet cement-based material with sufficient adhesive force, and even after the cement-based material has hardened, the adhesive sheet can be adhered from the surface of the cement-based material. It is intended that the pressure-sensitive adhesive layer can be removed without remaining on the surface. According to such an adhesive sheet, a cement-based structure can be manufactured without impairing a desired surface morphology, and the period required for curing the cement-based material can be significantly shortened, so that the construction period can be shortened.

(Adhesive layer)
The pressure-sensitive adhesive layer is an alkyl (meth) acrylate having 4 to 18 carbon atoms (also referred to as C _{4 to} C ₁₈ alkyl (meth) acrylate in the present disclosure. In the present disclosure, “(meth) acrylate” refers to methacrylate and acrylate. It is intended to include a polymer derived from a monomer component containing a monomer having at least one nitrogen-containing functional group (also referred to as a nitrogen-functional monomer in the present disclosure).

Preferable examples of C _{4 to} C ₁₈ alkyl (meth) acrylates are n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, lauryl acrylate, n-octyl acrylate, isononyl acrylate, isodecyl acrylate, isostearyl acrylate, iso. Myristyl acrylate, etc. Of these, 2-ethylhexyl acrylate, isooctyl acrylate, and n-octyl acrylate are preferable from the viewpoint of the balance between adhesiveness and peelability and low water permeability.

The nitrogen functional monomer is a monomer having at least one nitrogen-containing functional group. In order for the pressure-sensitive adhesive sheet to adhere well to the surface of a wet cement-based material, it is advantageous that the pressure-sensitive adhesive layer has a hydrophilic group. However, in cement-based materials containing cement that produces calcium hydroxide by hydration, ion-crosslinkable hydrophilic groups (such as carboxyl groups) are ion-crosslinked with calcium ions generated by the hydration reaction to form an adhesive layer. It may cause a decrease in adhesiveness with cement-based materials. In addition, this ionic cross-linking also affects the progress of hardening in cements that produce calcium hydroxide by hydration, which may result in delayed or deficient hardening. The nitrogen-containing functional group contained in the pressure-sensitive adhesive layer of the present disclosure is a hydrophilic group that is relatively difficult to interact with calcium ions due to its structure. Therefore, the nitrogen-functional monomer can contribute to the good adhesiveness of the pressure-sensitive adhesive layer to the wet cement-based material, and has physical properties such as more denseness, strength, and high durability by not hindering the curing of the cement-based material. It can also contribute to the production of high-quality cement-based structures.

Nitrogen-containing functional groups are intended to include all nitrogen-containing functional groups. The nitrogen-containing functional group is preferably a neutral to weakly basic group from the viewpoint of having little influence on the curing reaction of the cement-based material. Examples of the neutral to weakly basic group include pyrrolidone, amide, substituted amide, morpholine, caprolactam, and the like.

Preferred examples of nitrogen-functional monomers are N-vinyl-2-pyrrolidone (NVP), N, N-dimethylacrylamide (DMAA), N, N-diethylacrylamide, N-isopropylacrylamide from the viewpoint of hydrophilicity and cohesiveness. , Diacetoneacrylamide (DAAM), acryloylmorpholine, N-vinylcaprolactam, hydroxyethylacrylamide, octylacrylamide and the like.

In a preferred embodiment, the monomer component comprises C _{4 to} C ₁₈ alkyl (meth) acrylate: about 70 parts by weight to about 92 parts by weight, and nitrogen functional monomer: about 8 parts by weight to about 30 parts by weight. In the above embodiment, the amount of C _{4 to} C ₁₈ alkyl (meth) acrylate is preferably about 70 parts by mass or more, about 72 parts by mass or more, or about 74 parts by mass or more from the viewpoint of obtaining good adhesive strength. From the viewpoint of satisfactorily obtaining the advantages of blending the nitrogen functional monomer, it is preferably about 92 parts by mass or less, or about 91 parts by mass or less, or about 90 parts by mass or less. Further, in the above aspect, the amount of the nitrogen functional monomer is preferable from the viewpoint of obtaining good adhesiveness to the surface of the cement-based material having a high water content and good peeling and removing property of the pressure-sensitive adhesive layer after the cement-based material is cured. It is about 8 parts by mass or more, about 9 parts by mass or more, or about 10 parts by mass or more, and preferably 30 parts by mass or less, or about 28 parts by mass or less, or about 26 parts by mass from the viewpoint of obtaining good adhesive strength. It is as follows.

In a typical embodiment, the monomer component can include additional monomers having crosslinkable sites in addition to the above. By cross-linking, the cohesiveness is improved, and it is expected that the adhesive residue will be reduced when peeling from the adhesive surface. For example, when a benzophenone group-containing (meth) acrylate is used as an additional monomer, cross-linking by UV irradiation is possible. Further, for example, when a hydroxyl group-containing (meth) acrylate and a polyfunctional isocyanate compound are used as additional monomers, cross-linking by urethane bond is possible.

The amount of the additional monomer used based on a total of 100 parts by mass of the C _{4 to} C ₁₈ alkyl (meth) acrylate and the nitrogen functional monomer is, for example, about 0.001 part by mass or more from the viewpoint of obtaining good crosslinkability. Or it can be about 0.01 parts by mass or more, or about 0.05 parts by mass or more, and from the viewpoint of good adhesiveness, for example, about 10 parts by mass or less, or about 8 parts by mass or less, or about 5 parts by mass. Can be less than or equal to. When a hydroxyl group-containing (meth) acrylate and a polyfunctional isocyanate compound are used, the ratio (NCO / OH) of the isocyanate group equivalent of the polyfunctional isocyanate compound to the hydroxyl group equivalent of the hydroxyl group-containing (meth) acrylate is, for example, about 0.005 or more. It may be about 1.2 or less, or about 0.01 or more and about 0.5 or less.

In a preferred embodiment, the monomer component is an ethylenically unsaturated group from the viewpoint of improving adhesion to a wet cement-based material and from the viewpoint of preventing inhibition of the curing reaction of the cement-based material and allowing the curing reaction to proceed satisfactorily. It does not contain a carboxylic acid having an ethylenically unsaturated group (for example, (meth) acrylic acid), a phosphoric acid having an ethylenically unsaturated group, or a sulfonic acid having an ethylenically unsaturated group. In another preferred embodiment, in addition to the above-mentioned two viewpoints of adhesion and curing reaction, a balance with the viewpoint of more easily peeling and removing the pressure-sensitive adhesive sheet from the cement-based material before and after curing without residual adhesive layer. In view of this, the monomer component is a carboxylic acid having an ethylenically unsaturated group, a phosphoric acid having an ethylenically unsaturated group, and / or a sulfonic acid having an ethylenically unsaturated group, in total of C _{4 to} C ₁₈ alkyl. About 0.001 parts by mass or more, or about 0.01 parts by mass or more, or about 0.05 parts by mass or more, about 6 parts by mass or less, based on 100 parts by mass of the total of the (meth) acrylate and the nitrogen functional monomer. Alternatively, it may be contained in an amount of about 4 parts by mass or less, or about 2 parts by mass or less.

In a preferred embodiment, the glass transition temperature of the polymer derived from the monomer component containing the C _{4 to} C ₁₈ alkyl (meth) acrylate and the nitrogen functional monomer is determined from the viewpoint of obtaining good adhesion of the pressure-sensitive adhesive sheet to the surface of the cement-based material. It is about 25 ° C or lower, or about 10 ° C or lower, or about 0 ° C or lower, and from the viewpoint of a good balance between adhesiveness and cohesiveness, it is about -100 ° C or higher, or about -90 ° C or higher, or about -80 ° C. That is all.

In a typical embodiment, the pressure-sensitive adhesive layer is composed of a polymer derived from the above-mentioned monomer component containing C _{4 to} C ₁₈ alkyl (meth) acrylate and a nitrogen functional monomer, but does not impair the object of the present invention. The range may further include additional polymers. The amount of additional polymer may be about 25% by weight or less, or about 20% by weight or less, or about 15% by weight, based on the total weight of the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer may further contain additives such as antioxidants, pigments, dyes, fillers, light-resistant agents (ultraviolet absorbers, light stabilizers, etc.), tackifiers, plasticizers, and the like.

In a preferred embodiment, the thickness of the pressure-sensitive adhesive layer is about 5 μm or more, about 10 μm or more, or about 15 μm or more from the viewpoint of obtaining good adhesiveness of the pressure-sensitive adhesive sheet to the surface of the cement-based material, and from the viewpoint of material cost reduction. , About 300 μm or less, or about 200 μm or less, or about 150 μm or less.

FIG. 1 is a diagram showing one aspect of the pressure-sensitive adhesive sheet of the present disclosure. With reference to FIG. 1, in a preferred embodiment, the pressure-sensitive adhesive sheet 1 has a base material 11 having a first main surface and a second main surface facing each other, and a pressure-sensitive adhesive arranged on the first main surface of the base material. It has an agent layer 12. Such an adhesive sheet is advantageous in terms of transportability and workability because it can be transported as a roll, for example, and the pressure-sensitive adhesive layer can be sequentially attached to the surface of the cement-based material while unwinding the winding.

The substrate 11 typically includes a film 11a. As the film, a plastic film such as polyolefin (polypropylene, polyethylene, etc.), polyethylene terephthalate, polyvinyl chloride, paper, woven fabric, non-woven fabric, etc. can be used. The substrate is preferably water impermeable from the viewpoint of preventing evaporation from the surface of the cement-based material and maintaining its moist state.

In a preferred embodiment, the thickness of the base material is about 5 μm or more, or about 7 μm or more, or about 10 μm or more from the viewpoint of obtaining good strength, and about 400 μm from the viewpoint of reducing material cost and operability. Below, or about 300 μm or less, or about 250 μm or less. The color of the base material may be, for example, white, milky white, black, transparent, etc., but in the dark color, the sunlight is unevenly condensed, so that the temperature of the surface of the cement-based material under the adhesive tape varies, and the curing White and milky white are preferable from the viewpoint that the uniformity tends to be low and the visibility of the adhesive sheet tends to be low when the adhesive sheet is transparent.

The first main surface of the base material may be subjected to corona treatment, plasma treatment, and / or primer treatment in order to improve the adhesiveness between the pressure-sensitive adhesive layer and the base material. As the primer treatment, one or more primer layers selected from epoxy resin, vinyl copolymer having a carboxyl group, (meth) acrylic copolymer, polyester resin, polyether resin, polyurethane, rubber-based material and the like are formed. You can.

A mold release agent layer 11b may be provided on the second main surface of the base material 11. That is, in order to prevent the adhesive layer of the sheet wound in a roll shape from sticking to the base material of the sheet immediately below and not being able to be pulled out / peeled off, the adhesive layer of the sheet (on the inner peripheral side of the sheet) is used in the roll. A mold release agent layer can be provided on the surface in contact with the surface (the surface on the outer peripheral side of the sheet). Examples of the release agent layer include a coating layer of a low-adhesive substance, and examples of the low-adhesive substance include a release treatment agent made of a material such as fluorine-based, olefin-based, silicone-based, urethane-based, or acrylic-based. Can be used.

Further, the pressure-sensitive adhesive sheet may further have a release liner on the side opposite to the base material side of the pressure-sensitive adhesive layer. The release liner can be selected as desired from various release films, release papers and the like used for general pressure-sensitive adhesive sheets. However, due to the base material and the pressure-sensitive adhesive layer (with the release agent layer if necessary), according to the roll without a release liner, the pressure-sensitive adhesive sheet is applied to the surface of the cement-based material while unwinding the roll. It is preferable because it can be carried out, the construction is simple, and waste such as a release liner is not generated at the construction site.

The adhesive sheet can be produced by various methods. For example, a film for a base material is prepared, a primer layer as described above is formed on one of the main surfaces by coating or the like, and an adhesive for an adhesive layer is further applied on the primer layer, while the above-mentioned An adhesive sheet can be obtained by forming a mold release agent layer on the other main surface of the film by coating or the like.

When the pressure-sensitive adhesive sheet is attached to the surface of a wet cement-based material, the peel strength between the surface and the pressure-sensitive adhesive sheet can be preferably about 0.5 N / cm or more, or about 1 N / cm or more. The peel strength as described above is advantageous for obtaining a good curing effect. The peel strength may be, for example, about 8 N / cm or less, or about 6.5 N / cm or less, from the viewpoint of easy peeling of the pressure-sensitive adhesive sheet after the cement-based material is cured.

In a preferred embodiment, the peel strength when the pressure-sensitive adhesive sheet is attached to the surface of a wet cement-based material and peeled off after 7 days is about 0.5 N / cm or more, or about 1 N / cm from the viewpoint of promoting good curing. It is cm or more, or about 1.5 N / cm or more, and from the viewpoint of easy peeling of the adhesive sheet after the cement-based material is cured, it is about 8 N / cm or less, or about 7 N / cm or less, or about 6 N / cm or less. is there.

In a preferred embodiment, the peel strength between the first main surface and the pressure-sensitive adhesive layer is about 8 N / cm or more, and the peel strength between the second main surface and the pressure-sensitive adhesive layer is a pressure-sensitive adhesive sheet on the surface of the cement-based material. It can be about 0.1% or more and about 95% or less of the peel strength between the surface and the pressure-sensitive adhesive sheet when the above is attached. By controlling the peel strength as described above, while having good characteristics as an adhesive sheet, for example, even if the second main surface of the roll is in contact with the adhesive layer, the roll can be wound during construction. It can be solved with a small peeling force. If this peeling force is small, when the adhesive sheet is attached to the surface of the cement-based material while unrolling, the external force applied to the adhesive sheet of the already attached part is small, so that the already attached part is prevented from peeling. The workability is extremely good.

In a preferred embodiment, when the pressure-sensitive adhesive sheet is a roll, the peel strength at unwinding is such that the surface and the pressure-sensitive adhesive sheet when the pressure-sensitive adhesive sheet is attached to the surface of a wet cement-based material from the viewpoint of good workability. From the viewpoint of ease of manufacturing the pressure-sensitive adhesive sheet, it is about 0.001 N / cm or more, or about 0.01 N / cm or more, or about 0.1 N / cm or more.

<Manufacturing method of cement-based structures>
This disclosure also includes
It is a manufacturing method of cement-based structures.
Obtaining a cement-based material with an exposed surface,
When the exposed surface is in a wet state, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present disclosure is attached to the exposed surface.
Hardening cement-based materials to obtain cement-based structures, and removing adhesive sheets from cement-based structures,
Provide manufacturing methods including.

The cement-based material having an exposed surface can be formed by casting or spraying the cement-based material in the mold.

The time when the formwork is removed depends on the design strength of the target structure, the environment such as temperature and humidity at the site, the composition of the cement-based material, etc., but in the example embodiment, the material of the cement-based material the day after construction. The age is 8 to 15 hours, and the compressive strength of cement-based materials is about 2 N / mm ² or more.

Then, when the exposed surface is in a wet state, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present disclosure is attached to the exposed surface. That is, in an exemplary embodiment, the cement-based material is placed in the mold, and then the cement-based material loses fluidity to the extent that it can maintain its own shape (for example, hydration of cement up to a conversion rate of more than 50%). Immediately after the mold is removed, the adhesive sheet of the present disclosure is attached to the surface of the cement-based material in a wet state.

The peel strength between the surface and the pressure-sensitive adhesive sheet when the pressure-sensitive adhesive sheet is attached to the exposed surface can be preferably about 0.5 N / cm or more, or about 1 N / cm or more. The peel strength as described above is advantageous for obtaining a good curing effect. The peel strength may be, for example, about 8 N / cm or less, or about 6 N / cm or less, from the viewpoint of easy peeling of the pressure-sensitive adhesive sheet from the cement-based material after curing.

The cement-based material is then cured. Curing can proceed satisfactorily without the need for special treatments such as heating, cooling, watering, etc., but the present disclosure does not preclude further use of one or more of these treatments. In the exemplary embodiment, the period from application of the pressure-sensitive adhesive sheet to completion of curing is more than about 1 month, for example, about 3 months.

When the cement-based material is cured, a cement-based structure as a cured product is obtained. The adhesive sheet is peeled off from the cement-based structure manually or otherwise. In a preferred embodiment, the peel strength between the cement-based structure and the pressure-sensitive adhesive sheet can be about 8 N / cm or less, or about 6.5 N / cm or less. The peeling strength as described above is advantageous in that the pressure-sensitive adhesive sheet can be peeled off without leaving the pressure-sensitive adhesive layer on the cement-based structure. The peel strength may be, for example, about 0.5 N / cm or more, or about 1 N / cm or more, from the viewpoint of obtaining good adhesiveness of the pressure-sensitive adhesive sheet to the cement-based material before curing.

With the above procedure, a desired cement-based structure can be produced.

Examples of the cement-based structures of the present disclosure include various structures such as concrete structures such as buildings, roads, bridges, dams, tunnels, and harbor facilities. Since the pressure-sensitive adhesive sheet of the present disclosure has good adhesiveness to the surface of a wet cement-based material, it is also suitable for use under high temperature and high humidity conditions such as a tunnel.

Hereinafter, specific aspects of the present invention will be further described with reference to Examples, but the present invention is not limited to these Examples.

1. 1. Material Water-impermeable base film (80 μm thick polypropylene / polyethylene blend polyolefin film)
2EHA: 2-ethylhexyl acrylate, available from Nippon Catalyst Co., Ltd. BA: n-butyl acrylate, available from Mitsubishi Chemical Industries, Ltd. AA: acrylic acid, available from Toa Synthetic Co., Ltd. HEA: 2-hydroxyethyl acrylate, Osaka Organic Available from Chemical Industries, Ltd. NVP: N-Vinyl-2-pyrrolidone, Available from Wako Pure Chemical Industries, Ltd. DMAA: N, N-Dimethylacrylamide, Available from Kojin Film & Chemicals, Inc. DAAM: Diacetone Acrylamide , Available from Nippon Kasei Co., Ltd. ABP: Acryloyloxybenzophenone AEBP: Acryloyloxyethyl benzophenone Coronate ^TM L-45: Ethyl acetate solution with a solid content of 45% by mass of polyfunctional isocyanate compound, available from Soken Kagaku Co., Ltd. Agent: 3% by mass toluene solution of 1,1'-isophthaloylbis (2-methylaziridine) V-65: Azobis (2,4-dimethylvaleronitrile), available from Wako Pure Chemical Industries, Ltd.

2. Preparation of PSA solution (1) PSA solution (PSA-1)
90.00 parts by mass 2EHA, 10.00 parts by mass NVP, 0.10 parts by mass ABP, 233.33 parts by mass ethyl acetate (as a solvent), and 0.20 parts by mass V-65 (initiator). As) were mixed. Nitrogen gas was purged and reacted at 50 ° C. for 24 hours to obtain a 30% by mass ethyl acetate solution of PSA polymer (PSA-1).
(2) PSA solution (PSA-2 to PSA-11)
PSA-2 to PSA-11 were prepared in the same manner as PSA-1 except that the monomers having the compositions shown in Table 1 were used.

3. 3. Preparation of Adhesive Sheet [Example 1]
The PSA-1 prepared above was coated on a water-impermeable base film and dried in an oven at 100 ° C. for 5 minutes to form a PSA layer having a dry thickness of 30 μm. Using a FUSION UV system, the PSA layer was crosslinked by UV irradiation (UV-C intensity: 75 mJ / cm ² ) to obtain the PSA tape according to Example 1 as an adhesive sheet.

[Examples 2 to 7]
A PSA tape was obtained in the same manner as in Example 1 except that the PSA solution shown in Table 1 was used.

[Example 8]
0.67 parts by mass of Coronate ^TM L-45 was added to 100 parts by mass of PSA-8 (prepared as described above) to obtain a coating solution. This coating liquid is coated on a water-impermeable base film, dried in an oven at 100 ° C. for 5 minutes to form a coating layer having a dry thickness of 30 μm, and left at 25 ° C. for 7 days. The PSA tape according to the above was obtained.

[Example 9]
A PSA tape was obtained in the same manner as in Example 8 except that the PSA solution shown in Table 1 was used.

[Example 10]
A coating solution was obtained by adding 1.2 parts by mass of a bisamide-based cross-linking agent to 100 parts by mass of PSA-10 (prepared as described above). This coating liquid was coated on a water-impermeable base film and dried in an oven at 100 ° C. for 5 minutes to form a coating layer having a dry thickness of 30 μm to obtain a PSA tape according to Example 10.

[Comparison example]
A PSA tape according to Comparative Example was obtained in the same manner as in Example 1 except that PSA-11 was used as the PSA solution.

4. Evaluation (1) PSA glass transition temperature (Tg)
The dynamic viscoelastic properties of each PSA polymer were measured by ARES (manufactured by Leometric Scientific) in shear mode, frequency 1.0 Hz, measurement temperature range -40 ° C to 120 ° C, and heating rate 5.0 ° C. Evaluated at / minute. The peak temperature of tan δ (loss elastic modulus G ″ / storage elastic modulus G ′) was defined as Tg. The results are shown in Table 1.

(2) Peeling strength against the surface of mortar A test piece having a size of 10 mm × 100 mm was cut out from the PSA tape. A mortar plate having a size of 10 mm × 70 mm × 120 mm (manufactured by Nippon Tact Co., Ltd.) was used as a base material. As the mortar plate, a moisture meter (manufactured by Kett Science Institute Headquarters) showing a moisture value of less than 4% was used. With the PSA side of the PSA tape test piece facing the mortar plate, the PSA tape was laminated on the mortar plate at 25 ° C. with a 2.0 kg roller. After 20 minutes, the peel strength of the PSA tape against the surface of the mortar plate was evaluated by 90 ° peeling (Tencilon universal material testing machine RTC-1325A, manufactured by Orientec Co., Ltd.) at 25 ° C. and a peeling speed of 300 mm / min.

On the other hand, a similar mortar plate was immersed in water for 24 hours and then taken out. The water on the surface of the mortar plate was wiped off with a paper towel. As the mortar plate, a moisture meter (manufactured by Kett Science Institute Headquarters) showing a moisture value of 4% or more was used. With the PSA side of the PSA tape test piece facing the mortar plate, the PSA tape was laminated on the mortar plate at 25 ° C. with a 2.0 kg roller. After 20 minutes, the peel strength of the PSA tape against the surface of the mortar plate was evaluated by 90 ° peeling (Tencilon universal material testing machine RTC-1325A, manufactured by Orientec Co., Ltd.) at 25 ° C. and a peeling speed of 300 mm / min.

(3) Peeling strength against concrete surface A 70 mm × 120 mm size test piece was cut out from the PSA tape. Ready-mixed concrete (88 parts by mass of instant concrete manufactured by Cainz Corporation mixed with 12 parts by mass of water) was placed in a mold having a size of 10 mm × 70 mm × 120 mm and left at 25 ° C. for 24 hours. The formwork was removed (at this time, a moisture meter (manufactured by Ketsuto Scientific Research Institute Co., Ltd.) showing a moisture value of 7% or more was used), and the PSA side of the test piece was made to face the concrete surface. In this state, PSA tape was laminated on the concrete surface at 25 ° C. with a 2.0 kg roller. It could be attached well to concrete before hardening. The laminated concrete was heated in an oven at 60 ° C. for 1 week to complete the hardening of the concrete. The peel strength of the PSA tape on the concrete surface after being applied and cured before curing was evaluated by 90 ° peeling at 25 ° C. and a peeling speed of 300 mm / min in the same manner as in (2) above.

The PSA tape according to each example showed better peel strength with respect to the surface of the cement-based material in a wet state as compared with the PSA tape according to the comparative example. Furthermore, the PSA tape could be easily peeled off from the concrete surface even after a harsh environment of 60 ° C. for one week. In each of the Examples and Comparative Examples, no residual PSA was observed on the surface of the concrete after the PSA tape was peeled off and cured.

Preparation of Adhesive Sheet Roll [Example 11]
Polyethylene (registered trademark) NK350 (10% solid content preparation product, Japan Co., Ltd.) as a primer on the first main surface of an olefin film 80 μm thick (PP / PE / masterbatch = 57/38/5 (mass ratio)) (Available from catalyst) was coated with a gravure coater and the solvent was evaporated in a drying oven. Next, on the second main surface, KS-3703 (available from Shin-Etsu Chemical Co., Ltd.) / Ethyl acetate / CAT PL-50T (available from Shin-Etsu Chemical Co., Ltd.) = 10/90 / 0.3 (mass) The release agent of the addition type silicone (ratio) was applied with a gravure coater, and the solvent was evaporated in a drying oven. Further, a coating liquid obtained by adding 0.67 parts by mass of Coronate ^TM L-45 to 100 parts by mass of PSA-8 (prepared as described above) is applied to the first main surface by a knife coater. The coating was applied at an amount of 30 g / m ² , and then the coating liquid applied to the surface was dried with hot air in a drying oven. This was taken up by a take-up roll. This roll was left at 25 ° C. for 7 days to obtain a PSA sheet roll according to Example 11.

Peeling strength when unwinding the adhesive sheet roll The adhesive sheet roll shown in Example 11 is slit to a width of 5 cm, and a high-speed peeling tester (manufactured by Tester Sangyo Co., Ltd.) is used to peel off the adhesive sheet roll when unwinding. Was evaluated for each peeling speed.

As shown in Table 2, the peel strength of the PSA tape roll according to Example 11 at the time of unwinding is smaller than the peel strength of the wet cement-based material shown in Table 1 from the surface. That is, it is shown that the sheet can be unwound by pulling a roll while being attached to a wet cement-based material. In fact, the PSA tape roll according to Example 11 was able to unwind the roll even on a wet concrete surface with the adhesive force of the PSA side of the test piece unwound in advance to the concrete surface.

The adhesive sheet of the present disclosure can be suitably applied to the production of various cement-based structures such as buildings, roads, bridges, dams, tunnels, and harbor facilities. The present disclosure includes the following aspects 1 to 4.
[Aspect 1]
An adhesive sheet that covers the surface of a cement-based material such as concrete, mortar, or cement.
It has a pressure-sensitive adhesive layer containing a polymer derived from a monomer component containing an alkyl (meth) acrylate having 4 to 18 carbon atoms and a monomer having at least one nitrogen-containing functional group.
A pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer can be adhered to the surface of the cement-based material in a wet state and can be peeled off from the surface of the cement-based material after curing.
[Aspect 2]
The first aspect of the embodiment, wherein the monomer component comprises an alkyl (meth) acrylate having 4 to 18 carbon atoms: 70 to 90 parts by mass, and a monomer having at least one nitrogen-containing functional group: 10 to 30 parts by mass. Adhesive sheet.
[Aspect 3]
A roll formed by winding the adhesive sheet according to the first or second aspect.
[Aspect 4]
A method for manufacturing cement-based structures such as concrete, mortar, or cement.
To obtain the cement-based material having an exposed surface,
Attaching the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of aspects 1 to 3 to the exposed surface when the exposed surface is in a wet state.
The cement-based material is cured to obtain a cement-based structure, and
Removing the adhesive sheet from the cement-based structure,
Manufacturing method, including.

1 Adhesive sheet 11 Base material 11a Film 11b Release agent layer 12 Adhesive layer

Claims (3)

An adhesive sheet that covers and cures the surface of cement-based materials such as concrete, mortar, and cement.
Co derived alkyl (meth) acrylates having 4 to 18 carbon atoms, pyrrolidone, amide, substituted amide, morpholine, and a nitrogen-containing functional group selected from the group consisting of caprolactam monomer component containing a monomer having at least one It has an adhesive layer containing a polymer and
The pressure-sensitive adhesive layer can be adhered to the surface of the cement-based material in a wet state and can be peeled off from the surface of the cement-based material after curing.
The monomer component, the alkyl having 4 to 18 carbon atoms (meth) acrylate: 70 to 90 parts by weight, and a monomer having at least one of the nitrogen-containing functional groups: see contains 10 to 30 parts by weight,
The total content of the carboxylic acid having an ethylenically unsaturated group, the phosphoric acid having an ethylenically unsaturated group, and the sulfonic acid having an ethylenically unsaturated group in the monomer component is an alkyl having 4 to 18 carbon atoms. An adhesive sheet having a total of 6 parts by mass or less based on 100 parts by mass of the total of the (meth) acrylate and the monomer having at least one nitrogen-containing functional group . A roll formed by winding the adhesive sheet according to claim 1. A method for manufacturing cement-based structures such as concrete, mortar, or cement.
To obtain the cement-based material having an exposed surface,
When the exposed surface is in a wet state, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to claim 1 is attached to the exposed surface to cure the surface.
Hardening the cement-based material to obtain a cement-based structure, and removing the adhesive sheet from the cement-based structure.
Manufacturing method, including.

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