Adhesive tape

Abstract

An adhesive tape according to the present invention is provided with: a paper substrate; an adhesive agent layer provided on one surface side of the paper substrate; a release layer provided on another surface side of the paper substrate; and a sealer layer provided between the paper substrate and the release layer. The sealer layer includes a polymer having a hydroxyl group, and the polymer having a hydroxyl group is crosslinked by a crosslinking agent.

Description

Adhesive tape

[0001] The present invention relates to an adhesive tape comprising a paper substrate.

[0002] In recent years, recycling of packaging materials such as cardboard has been encouraged from an environmental protection perspective. Adhesive tape is widely used in packaging materials to seal the contents, and adhesive tape is often attached to used packaging materials. Among the adhesive tapes used in such packaging materials, there are some, such as kraft tape made from paper as the base material, that can be recycled together with the packaging material, eliminating the need to remove the adhesive tape during the recycling process.

[0003] For example, Patent Document 1 discloses an adhesive tape that is highly recyclable when recycled together with paper materials such as packaging materials, comprising a paper substrate, an adhesive layer provided on one side of the paper substrate, and a release agent layer provided on the other side of the paper substrate, wherein the amount of residue in a decomposition test is 50% or less.

[0004] Furthermore, in the manufacturing process of adhesive tapes, when applying a release agent, a sealing layer is sometimes applied to the tape substrate, such as kraft paper, to prevent the release agent from impregnating the substrate. Plastics such as PE laminate have been used to form the sealing layer, but in recent years, from the perspective of reducing plastic use, there is a demand to avoid using plastic in the sealing layer. As an alternative to plastic, for example, as shown in Patent Document 1, it is being considered to impart sealing properties by applying water-based coating agents such as latex, polyvinyl alcohol, polyurethane, and starch to the tape substrate.

[0005] Japanese Patent Publication No. 2021-107512

[0006] Release sheets using starch as a sealant have several advantages compared to other sealants: starch is a natural material, has a high biodegradability, is biodegradable, and is easily recycled. ２It has advantages in that it is easy to reduce emissions, is inexpensive, and is readily available. However, starch is a polymer that contains hydroxyl groups, and when such polymers are used as a sealing layer, the sealing layer may dissolve if it is placed in a high-temperature, high-humidity environment or comes into contact with hot water. Therefore, for example, when adhesive tape stored in a roll is unfolded, the sealing layer may crack, and the sealing agent itself or the release agent layer formed on top of the sealing layer may adhere to the adhesive surface of the tape, causing problems such as poor adhesion and poor unfolding.

[0007] Furthermore, for example, when a water-based release agent is used, the water used to dilute the release agent is heated during the manufacturing process of the adhesive tape. This high-temperature water comes into contact with the sealing layer containing polymers such as starch, causing the polymers to dissolve and making it difficult for the sealing layer to support the release layer. As a result, the release properties become less pronounced, leading to heavy unfolding and potentially causing problems such as the tape breaking while being unfolded from a roll.

[0008] Therefore, the present invention aims to provide an adhesive tape in which the sealing layer contains a polymer having hydroxyl groups such as starch, and which can prevent cracking of the sealing layer even when placed in a high-temperature, high-humidity environment or in contact with hot water, and which also has good unfolding strength.

[0009] The inventors of the present invention diligently studied measures to prevent cracking of the sealant layer and found that the above problem can be solved by crosslinking a polymer having hydroxyl groups with a crosslinking agent, thereby completing the present invention as follows. That is, the present invention provides the following [1] to

[13] .

[0010] [1] An adhesive tape comprising a paper substrate, an adhesive layer provided on one side of the paper substrate, a release layer provided on the other side of the paper substrate, and a sealant layer provided between the paper substrate and the release layer, wherein the sealant layer contains a polymer having hydroxyl groups, and the polymer having hydroxyl groups is crosslinked. [2] The adhesive tape according to [1], wherein the polymer having hydroxyl groups is starch. [3] The adhesive tape according to [1] or [2], wherein the polymer is crosslinked with a crosslinking agent, and the crosslinking agent is an aqueous crosslinking agent. [4] The adhesive tape according to any one of [1] to [3], wherein the polymer is crosslinked with a crosslinking agent, and the crosslinking agent is an epoxy group-containing crosslinking agent or an isocyanate crosslinking agent. [5] The adhesive tape according to any one of [1] to [4], wherein the gel fraction of the sealant layer is 10% or more. [6] The dry coating amount of the sealant layer is 2 g / m ２ 30g / m or more ２ The adhesive tape according to any one of the following items [1] to [5]: [7] The adhesive tape according to any one of the following items [1] to [6], wherein the release layer contains a water-based release agent. [8] The adhesive tape according to [7], wherein the water-based release agent is a non-silicone-based release agent. [9] The adhesive tape according to any one of the following items [1] to [8], wherein the adhesive layer contains a rubber-based adhesive.

[10] The adhesive tape according to [9], wherein the rubber-based adhesive contains natural rubber.

[11] The adhesive tape according to any one of the following items [1] to

[10] , wherein the adhesive layer has air bubbles inside.

[12] The adhesive tape according to

[11] , wherein the foaming ratio of the adhesive layer measured by a compression test is 1.5 times or more.

[13] The adhesive tape according to

[11] or

[12] , wherein the average bubble diameter of the air bubbles contained in the adhesive layer is 70 μm or less.

[0011] According to the present invention, the sealing layer contains a polymer having hydroxyl groups, such as starch, and even when placed in a high-temperature, high-humidity environment or in contact with hot water, cracking of the sealing layer can be prevented, and an adhesive tape with good unfolding strength can be provided.

[0012] This is a schematic cross-sectional view showing one embodiment of adhesive tape. This is a schematic diagram showing a method for measuring the expansion ratio by a compression test.

[0013] [Adhesive Tape] The adhesive tape of the present invention comprises a paper substrate, an adhesive layer provided on one side of the paper substrate, a release layer provided on the other side of the paper substrate, and a sealant layer provided between the paper substrate and the release layer. That is, as shown in Figure 1, the adhesive tape 10 comprises a release layer 11, a sealant layer 12, a paper substrate 13, and an adhesive layer 14 in this order.

[0014] (Sealing layer) In the present invention, the sealing layer 12 contains a polymer having crosslinked hydroxyl groups. In this case, the polymer having hydroxyl groups is crosslinked. The sealing layer 12 may have a crosslinked ether structure. The adhesive tape of the present invention can appropriately prevent the release layer from impregnating the paper substrate by using a polymer having hydroxyl groups. Furthermore, because the polymer having hydroxyl groups is crosslinked, the sealing layer can be prevented from dissolving even when placed in a high temperature and high humidity environment or when hot water comes into contact with it, thereby preventing cracking of the sealing layer, and further reducing the force required to unfold the adhesive tape, making it easier to unfold.

[0015] <Polymers containing hydroxyl groups> Specific examples of polymers containing hydroxyl groups include starch, polyvinyl alcohol resin (PVA resin), acrylic resin, and carboxymethylcellulose. Among these, starch or PVA resin is preferred, and among these, starch is more preferred from the viewpoint of cost, reduction of environmental impact, and ease of availability. A single polymer containing hydroxyl groups may be used, or two or more may be used in combination.

[0016] Examples of starch include starch or modified starch that has been heated in the presence of water, gelatinized, and dried so that the starch dissolves or swells in water at room temperature. The starch may be unprocessed or further processed before use. Examples of processing include conventionally known etherification, acetylation, oxidation, hydroxypropylation, and combinations thereof. Among the above, the starch preferably contains modified starch, more preferably contains at least one selected from oxidized starch and hydroxypropyl starch, and even more preferably contains oxidized starch. When using starch as a polymer having hydroxyl groups, for example, α-starch that has been heated in the presence of water and gelatinized may be used.

[0017] Furthermore, when using starch as a polymer containing hydroxyl groups, commercially available starch may be used. Examples of commercially available starches include Amicol HF, Amicol C, Amicol KF, Amicol HG-N, Amicol BJ-2, ​​Amicol W, Starch MH-A, Amicol A, Amicol FW (all manufactured by Nippon Denko Chemical Co., Ltd.), Nisshoku Alstar, Nisshoku Alstar H, Nisshoku Waxy α (all manufactured by Nippon Shokuhin Kako Co., Ltd.), Corn αY, Corn αS-1, Industrial Tapioca α, Industrial Tapioca αTP-2, Wheat Starch αWA-105 (manufactured by Sanwa Starch Industry Co., Ltd.), Ace A, Ace C, Gelpro F107E (all manufactured by Oji Corn Starch Co., Ltd.).

[0018] When using oxidized starch as the polymer having hydroxyl groups, the weight-average molecular weight of the oxidized starch is preferably 10,000 to 150,000, more preferably 25,000 to 100,000, and even more preferably 35,000 to 80,000. When the weight-average molecular weight of the oxidized starch is within the above range, the gel fraction of the sealing agent layer can be adjusted to a desired range, preventing the sealing agent layer from dissolving even when placed in a high-temperature, high-humidity environment or when hot water comes into contact with it, thereby making it easier to prevent cracking of the sealing agent layer. The weight-average molecular weight of the oxidized starch can be obtained by measuring it using the GPC method under the following conditions. Column: Two TSKgel G6000PWxl (Tosoh Corporation) and TSKgel G3000PWxl (Tosoh Corporation) columns linked together. Guard column: Guardcolum PWxl (Tosoh Corporation). Eluent: Aqueous solutions of sodium dihydrogen phosphate dihydrate (20 mmol / L) and disodium hydrogen phosphate dodecahydrate (20 mmol / L). Flow rate: 1.0 mL / min. Column temperature: 45°C. Sample concentration: 0.5%. Standards: Polyethylene glycol (Mw1010, 4040, 16100, 44200, 146000).

[0019] PVA resin is obtained by polymerizing vinyl esters according to conventionally known methods, and then saponifying, i.e., hydrolyzing, the polymer. Generally, alkalis or acids are used for saponification, but alkalis are preferred. Only one type of PVA resin may be used, or two or more types may be used in combination. Alternatively, a derivative obtained by adding other monomers to the hydroxyl groups of polyvinyl alcohol after saponification may also be used.

[0020] Examples of vinyl esters include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versaticate, vinyl laurate, vinyl stearate, and vinyl benzoate. The polymerization method for vinyl esters is not particularly limited, but examples include solution polymerization, bulk polymerization, and suspension polymerization.

[0021] The PVA resin may be unmodified PVA or modified PVA. Examples of unmodified PVA include saponified polyvinyl esters. Examples of modified PVA include saponified polymers of vinyl esters and other unsaturated monomers. Examples of other unsaturated monomers include monomers other than vinyl esters that have a carbon-carbon double bond such as a vinyl group. Examples of such monomers include olefins, (meth)acrylic acid and its salts, (meth)acrylic acid esters, unsaturated acids other than (meth)acrylic acid, their salts and esters, (meth)acrylamides, N-vinylamides, vinyl ethers, nitriles, vinyl halides, allyl compounds, vinylsilyl compounds, isopropenyl acetate, sulfonic acid group-containing compounds, amino group-containing compounds, and the like.

[0022] The degree of saponification of the PVA resin is preferably 50 to 99.5 mol%, and more preferably 60 to 90 mol%, from the viewpoint of ensuring water solubility and facilitating good recyclability of the adhesive tape. The above degree of saponification is measured in accordance with JIS K6726. The degree of saponification indicates the proportion of units that are actually saponified into vinyl alcohol units out of the units that are converted to vinyl alcohol units by saponification. The method for adjusting the degree of saponification is not particularly limited. The degree of saponification can be appropriately adjusted by the saponification conditions, i.e., the hydrolysis conditions.

[0023] The degree of polymerization of the PVA resin is not particularly limited, but is, for example, 700 to 3000, preferably 1000 to 2500, and more preferably 1500 to 2000. If the degree of polymerization is above the lower limit, the adhesive strength on the back of the adhesive tape tends to be kept low. Also, if the degree of polymerization is above the lower limit, the sealant plays a role in reinforcing the paper substrate, preventing the adhesive tape from breaking due to its adhesive strength when peeled off, thus preventing a portion of the adhesive tape from remaining on the adherend, and making it easier to improve the unfolding force when, for example, a roll of adhesive tape is unfolded.

[0024] <Crosslinking Agent> The polymer containing hydroxyl groups in the sealant layer may be crosslinked with a crosslinking agent. The crosslinking agent is not particularly limited as long as it can crosslink polymers containing hydroxyl groups, but examples include epoxy group-containing crosslinking agents, isocyanate crosslinking agents, aziridine crosslinking agents, and zirconium ammonium carbonate. Among these, at least one selected from epoxy group-containing crosslinking agents, isocyanate crosslinking agents, aziridine crosslinking agents, and zirconium ammonium carbonate is preferred, and at least one selected from epoxy group-containing crosslinking agents and isocyanate crosslinking agents is more preferred.

[0025] Examples of epoxy group-containing crosslinking agents include polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, epichlorohydrin adducts of polyamine polyamides and other epichlorohydrin compounds, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, and propylene glycol. Examples include diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycidyl adipate ester, diglycidyl o-phthalate ester, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether. Among these, at least one selected from bisphenol A type epoxy resin and epichlorohydrin compounds is preferred, epichlorohydrin compounds are more preferred, and polyamide epichlorohydrin resin is even more preferred.

[0026] Examples of isocyanate crosslinking agents include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate.

[0027] Examples of aziridine crosslinking agents include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide).

[0028] As the crosslinking agent, it is preferable to use an aqueous crosslinking agent. Although a solvent-based crosslinking agent may be used as the crosslinking agent, generally, a solvent-based crosslinking agent or a sealer may fall under dangerous goods under the Fire Service Act. Therefore, by using an aqueous crosslinking agent instead of a solvent-based crosslinking agent, it becomes easier to prevent damages such as explosion and fire during the storage of the crosslinking agent or the manufacturing process of the adhesive tape. Also, by using an aqueous crosslinking agent, it becomes easier to prevent workers from suffering health damages such as solvent poisoning during the manufacturing process of the adhesive tape and to comply with VOC regulations. Furthermore, by using an aqueous crosslinking agent, it becomes easier to be compatible with a polymer having a hydroxyl group when the crosslinking agent is blended, and the polymer having a hydroxyl group is more likely to be properly crosslinked. Note that examples of the aqueous crosslinking agent include those in which the crosslinking agent is dispersed in water or a mixed solvent of water and an organic solvent such as alcohol, and reactive compounds that react with functional groups in an aqueous resin (acrylic resin, urethane resin, epoxy resin, PVA resin, PAA resin, starch, etc.) to cause insolubilization or infusibilization (crosslinking reaction). Examples of the solvent-based crosslinking agent include reactive compounds that are used in an organic solvent and react with a resin (acrylic, polyester, polyurethane, epoxy, alkyd, etc.) to form a three-dimensional network structure.

[0029] The sealer layer is preferably formed by applying a mixed solution (coating solution) containing, for example, a polymer having a hydroxyl group and a crosslinking agent. As a result, the sealer layer is formed by mixing a polymer having a hydroxyl group and a crosslinking agent. Note that the coating solution is generally formed by diluting it with a diluting solvent such as water or a mixed solvent of water and an alcohol, applying it to a paper substrate, and then drying it. The crosslinking agent may, for example, crosslink the polymer having a hydroxyl group with the crosslinking agent by heating during drying, but crosslinking may also be performed by other means than heating during drying. The drying temperature of the coating solution is not particularly limited, but it is preferably performed at 80 to 160 °C for 10 seconds to 30 minutes.

[0030] Furthermore, the sealing layer may be formed by first applying a coating solution containing either a polymer having hydroxyl groups or a crosslinking agent, and then applying another coating solution containing the other on top of the coating film. In this method as well, the polymer and the crosslinking agent are mixed, and the polymer is crosslinked by the crosslinking agent, thereby forming the sealing layer. Among these methods, it is preferable to first apply a coating solution containing a polymer having hydroxyl groups, and then apply the crosslinking agent on top of the coating film to form the sealing layer. When forming the sealing layer in this way, the crosslinking agent is impregnated into the coating film formed by the polymer, and as a result, the polymer having hydroxyl groups and the crosslinking agent are mixed and formed, making it easier to form a properly formed and crosslinked sealing layer. The coating solution containing the polymer or crosslinking agent may be formed by diluting it with a diluting solvent, applying it to a paper substrate, and then drying it, similar to the coating solution containing the polymer and crosslinking agent. In this case, the coating solution containing the polymer or crosslinking agent may be dried after application and before applying the next coating solution, but it may also be applied without drying. From the viewpoint of uniformly crosslinking the polymer having hydroxyl groups and making it easier to prevent cracking of the layer, it is preferable to form the sealing layer by applying a mixture containing a polymer having hydroxyl groups and a crosslinking agent.

[0031] The content of the crosslinking agent in the plugging agent layer is preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 3 to 7 parts by mass, based on 100 parts by mass of the polymer having a hydroxyl group. When the content of the crosslinking agent is at least the above lower limit value, the polymer having a hydroxyl group can be crosslinked evenly. Therefore, even when placed in a high-temperature and high-humidity environment or contacted with hot water, dissolution of the plugging layer can be prevented, thereby making it easier to prevent layer cracking of the plugging layer and making it easier to improve the unfolding force of the adhesive tape. Also, when the content of the crosslinking agent is at most the above upper limit value, a certain flexibility is imparted to the adhesive tape, and handling properties and followability can be ensured. The crosslinking agent may be used alone or in combination of two or more. Note that the crosslinking agent and the polymer having a hydroxyl group may be diluted with volatile components such as water, but in this specification, the content of the crosslinking agent and the polymer having a hydroxyl group means a value based on the solid content excluding the volatile components.

[0032] The plugging agent layer preferably has a gel fraction of 10% by mass or more, more preferably 13% by mass or more, even more preferably 20% by mass or more, and still more preferably 30% by mass or more. When the gel fraction is at least the above lower limit value, dissolution of the plugging layer can be prevented even when placed in a high-temperature and high-humidity environment or contacted with hot water, thereby making it easier to prevent layer cracking and the like of the plugging agent layer. The gel fraction of the plugging agent layer may be any of 35% by mass or more, 40% by mass or more, 45% by mass or more, or 50% by mass or more. Also, the gel fraction of the plugging agent layer is not particularly limited as long as it is 100% by mass or less. However, from the viewpoint of imparting a certain flexibility to the adhesive tape and ensuring handling properties and followability, it is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. The gel fraction can be determined by the measurement method described in the examples below. Also, the gel fraction can be appropriately adjusted according to the types of the polymer having a hydroxyl group and the crosslinking agent, the content of the crosslinking agent in the plugging agent layer, and the formation method of the plugging agent layer.

[0033] The blocking agent layer preferably has a bio-based content of 85% or more, more preferably 90% or more, and even more preferably 95% or more. When the bio-based content is at least the above lower limit value, the load on the global environment is reduced, and the recyclability of the adhesive tape is also likely to be improved. The higher the bio-based content, the better, as long as it is 100% or less. Practically, for example, it is 99% or less, preferably 98% or less. The bio-based content is a value measured in accordance with ASTM D6866 and can be estimated from the carbon isotope content with a mass number of 14.

[0034] The blocking agent layer preferably has a coating amount after drying of 2 g / m ２ or more and 30 g / m ２ or less, more preferably 3 g / m ２ or more and 20 g / m ２ or less, and even more preferably 3.5 g / m ２ or more and 10 g / m ２ or less. When the coating amount after drying of the blocking agent layer is at least the above lower limit value, the release agent remains on the surface of the paper substrate, and it becomes easier to reduce the unfolding force of the adhesive tape. Also, when the coating amount after drying of the blocking agent layer is at most the above upper limit value, the environmental load is likely to be reduced.

[0035] In addition to the polymer having a hydroxyl group and the crosslinking agent, additives may be appropriately blended in the blocking agent layer as needed. The additives may be appropriately mixed into the coating solution and applied together with the polymer having a hydroxyl group, the crosslinking agent, or the polymer having a hydroxyl group and the crosslinking agent.

[0036] (Release layer) The adhesive tape of the present invention includes a release layer on the surface of the paper substrate opposite to the surface provided with the adhesive layer. The release layer is preferably a layer including a release agent. By providing the release layer, for example, the adhesive tape stored in a roll shape can be unfolded without damaging the adhesive tape.

[0037] As a release agent, an aqueous release agent is preferred. Generally, when using an aqueous release agent, release properties are difficult to exhibit and the spreading force tends to be heavy, but when using the sealing agent layer of the present invention, the spreading force tends to be lighter. Examples of aqueous release agents include water, or a mixture of water and an organic solvent such as alcohol that has been diluted with water. As an aqueous release agent, a non-silicone release agent is preferred, and an aqueous dispersion of a long-chain alkyl group-containing compound is more preferred. Here, "non-silicone release agent" refers to a release agent that does not contain a compound with a siloxane bond (-Si-O-Si-) as its main skeleton or a composition containing the same, and refers to one that imparts release properties using non-siloxane compounds such as hydrocarbon-based, fluorine-based, fatty acid-based, wax-based, acrylic-based, urethane-based, and ester-based compounds. Furthermore, the release agent is not limited to an aqueous release agent, and other release agents such as solvent-type release agents diluted with a solvent, or solvent-free release agents that have not been diluted with a solvent may be used. For example, a solvent dispersion of a long-chain alkyl group-containing compound or a solvent-free silicone-based release agent can be used.

[0038] In long-chain alkyl group-containing compounds, the long-chain alkyl group is preferably an alkyl group having 8 or more carbon atoms. The number of carbon atoms may be 10 or more, or 12 or more. The long-chain alkyl group is preferably an alkyl group having 30 or fewer carbon atoms. The number of carbon atoms may be 28 or less, or 26 or less. Furthermore, it is preferable that the long-chain alkyl group-containing compound has a long-chain alkyl group in its side chain.

[0039] Examples of long-chain alkyl group-containing compounds include long-chain alkyl group-containing polyvinyl resins, long-chain alkyl group-containing alkyd resins, long-chain alkyl group-containing acrylic resins, and long-chain alkyl group-containing polyester resins. Among these, long-chain alkyl group-containing polyvinyl resins are preferred.

[0040] The basis weight of the release layer after drying is not particularly limited, but for example, 0.05 g / m² ２ 5g / m or more ２ Preferably, the following is 0.07 g / m ２ 3g / m or more ２ More preferably, 0.1 g / m ２ 1g / m or more２ More preferably, 0.2 g / m ２ 0.45g / m or more ２ The following is true: By keeping the basis weight of the release layer above a certain level after drying, it becomes easier to reduce the force required to unfold the adhesive tape. Also, by keeping the basis weight of the release layer below a certain level after drying, it becomes easier to prevent defects such as cracking of the release layer.

[0041] The release layer may contain additives other than the above-mentioned release agent, such as photopolymerization initiators, inert particles, and antioxidants, as appropriate. The release layer can be formed by forming a sealant layer on the surface of a paper substrate, then applying a release agent diluted with water or a solvent to the surface of the sealant layer, and heating and drying as necessary. In the manufacturing process of adhesive tape, when forming a release layer using a water-based release agent, heating and drying may be performed after applying a release agent diluted with water, but in this process the water may become hot, and the sealant layer may be exposed to hot water. In the present invention, even if the sealant layer is exposed to hot water, the polymer having hydroxyl groups contained in the sealant layer does not dissolve because it is crosslinked. Therefore, even if heating and drying are performed after applying a release agent diluted with water, it is possible to prevent the dissolution of the sealant layer and the resulting damage to the adhesive tape during deployment.

[0042] (Paper Substrate) Examples of paper substrates include paper sheets such as kraft paper, glassine paper, and fine paper, with kraft paper being preferred. Examples of kraft paper include unbleached kraft paper, semi-bleached kraft paper, bleached kraft paper, kraft paper that has been processed with a crunch pack to give it stretchability, and kraft paper that has been processed with a wet strength to give it wet strength.

[0043] The basis weight of the paper substrate is not particularly limited, but is preferably 10 to 150 g / m². ２ More preferably, 30 to 130 g / m² ２ Therefore, if the basis weight of the paper substrate is above these lower limits, the strength of the adhesive tape will increase, and if it is below these upper limits, the thickness of the adhesive tape can be reduced, resulting in improved workability and other advantages.

[0044] (Adhesive Layer) The adhesive tape of the present invention has an adhesive layer provided on one side of the paper substrate. The adhesive layer is a layer formed by an adhesive. The type of adhesive is not particularly limited, but examples include acrylic adhesives, rubber adhesives, urethane adhesives, polyvinyl ether adhesives, and silicone adhesives. These adhesives contain a resin component that serves as the main component of the adhesive, such as acrylic resin, rubber component, urethane resin, polyvinyl ether, or silicone resin, and it is preferable that the main component is further compounded with appropriate additives.

[0045] Of the adhesives described above, it is preferable to use a rubber-based adhesive for the adhesive layer. By using a rubber-based adhesive, the adhesive layer is given a certain level of hardness, making it easier to maintain a certain shape even if, for example, many air bubbles are formed inside, as described later. Rubber-based adhesives use a rubber component as the main component, as described above, and examples of such rubber components include natural rubber, ethylene-propylene rubber (EPDM), chloroprene rubber (CR), isoprene rubber, butyl rubber (IIR), butadiene rubber (BR), and chlorosulfonated polyethylene. Among these, natural rubber is preferred. By using natural rubber, it is easier to improve the bio-content of the adhesive layer and reduce the burden on the global environment. Furthermore, when using natural rubber, it is also preferable to use it in combination with a thermoplastic elastomer such as a styrene-based thermoplastic elastomer, as described later.

[0046] Thermoplastic elastomers are also preferred as rubber components. Among thermoplastic elastomers, styrene-based thermoplastic elastomers are particularly preferred. By using thermoplastic elastomers, the adhesive can be a hot-melt adhesive, which makes it easier to form air bubbles appropriately, as will be described later, and thus improves packaging performance. Among styrene-based thermoplastic elastomers, those obtained by block copolymerization of styrene and isoprene are preferably used, specifically styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene block copolymer (SI), etc., with SIS being more preferred.

[0047] The rubber-based adhesive may contain a tackifier in addition to the rubber component. The tackifier imparts tackiness to the rubber-based adhesive, improving the adhesive performance of the adhesive layer. Examples of tackifiers include rosin resins, terpene resins, coumarone-indene resins, petroleum resins, and terpene-phenol resins, among which petroleum resins are preferred. The content of the tackifier in the adhesive is, for example, 20 to 200 parts by mass, preferably 50 to 150 parts by mass, per 100 parts by mass of the rubber component.

[0048] Rubber-based adhesives may contain a softening agent in addition to the tackifier mentioned above. The inclusion of a softening agent in a rubber-based adhesive softens the adhesive, making it easier to improve its applicability and adhesive performance. Examples of softening agents include mineral oils (also called process oils) such as paraffin oil and naphthenic oil, plasticizers such as ester-based plasticizers represented by diisodecylphthalate, liquid polybutene, liquid lanolin, liquid polyisoprene, and liquid polyacrylate. The softening agent content in the adhesive is, for example, 5 to 80 parts by mass, preferably 10 to 50 parts by mass, per 100 parts by mass of the rubber component.

[0049] In addition to the above, the rubber-based adhesive constituting the adhesive layer may also contain known additives used in adhesives, such as fillers, antioxidants, anti-aging agents, UV inhibitors, and pigments, as appropriate.

[0050] Examples of fillers include calcium carbonate, zinc oxide, silica, aluminum silicate, talc, diatomaceous earth, silica sand, pumice powder, slate powder, mica powder, asbestos, aluminum sol, alumina white, aluminum sulfate, barium sulfate, lithopone, calcium sulfate, molybdenum disulfide, graphite, glass fiber, glass sphere, single-crystal potassium titanate, carbon fiber, activated zinc oxide, zinc carbonate, magnesium oxide, basic magnesium carbonate, litharge, red lead, lead white, calcium hydroxide, activated calcium hydroxide, titanium dioxide, etc. The content of the filler in the adhesive is not particularly limited, but for example, in a rubber-based adhesive, it is, for example, 0.1 to 150 parts by mass, preferably 1 to 100 parts by mass, and more preferably 3 to 80 parts by mass, per 100 parts by mass of rubber component.

[0051] Examples of anti-aging agents include naphthylamine compounds, diphenylamine compounds, p-phenylenediamine compounds, other amine compounds, amine compound mixtures, quinoline compounds, hydroquinone derivatives, monophenol compounds, bisphenol compounds, trisphenol compounds, polyphenol compounds, and thiobisphenol compounds. The proportion of the anti-aging agent is not particularly limited, but for example, in rubber-based adhesives, it is usually 0.1 to 5 parts by mass, preferably 0.5 to 2 parts by mass, per 100 parts by mass of the rubber component.

[0052] The basis weight of the adhesive layer is not particularly limited, but is preferably 3 to 50 g / m². ２ More preferably 10 to 40 g / m ２ Therefore, by setting the basis weight of the adhesive layer to be above the lower limit, the adhesive strength tends to increase. Also, by setting the basis weight of the adhesive layer to be below the upper limit, adhesive strength corresponding to the thickness can be obtained. Note that when the adhesive layer is formed from a solvent-diluted adhesive composition as described later, the basis weight of the adhesive layer refers to the basis weight after drying.

[0053] The thickness of the adhesive layer is not particularly limited, but is preferably 10 to 150 μm, and more preferably 15 to 50 μm. By making the thickness of the adhesive layer greater than or equal to the lower limit mentioned above, the adhesive strength tends to increase.

[0054] The adhesive layer is preferably formed from an adhesive composition comprising a main component (resin component) constituting the adhesive, and optionally added tackifiers, softeners, and other additives. The adhesive composition may be a solvent-diluted type, diluted with a solvent, or it may be a hot-melt type, for example, without being diluted with a solvent, but the hot-melt type is preferred. Among these, a hot-melt type rubber-based adhesive is preferred.

[0055] The method for preparing the adhesive composition is not particularly limited, and may be, for example, by mixing the components constituting the adhesive composition in a stirrer or the like. In the case of a hot-melt type, it is preferable to heat and mix the components above the melting temperature of the main resin component.

[0056] <Air bubbles> It is preferable that the adhesive layer has air bubbles inside. Having air bubbles makes it easier to improve the packaging performance of the adhesive tape while suppressing the amount of adhesive used. The air bubbles may be formed by the evaporation of water, for example, or they may be derived from foaming particles, but among these, it is preferable that they are formed by the evaporation of water.

[0057] The method for forming bubbles by evaporating water is not particularly limited, but for example, in the manufacturing process of adhesive tape, water can be applied to the side of the paper substrate opposite to the side with the sealing agent layer, then the adhesive composition can be applied on top of that, and the resulting adhesive tape can be heated and dried to evaporate the water and form bubbles. When the water evaporates, the sealing agent has soaked into the paper substrate to a certain extent, which suppresses the water trapped between the paper substrate and the adhesive layer from soaking into the paper substrate. As a result, the evaporated water moves to the adhesive layer and forms bubbles. Furthermore, using a water-soluble polymer such as starch in the sealing layer can improve the gas barrier properties and increase the foaming ratio of the bubbles. The basis weight of the water when applying water to the paper substrate is not particularly limited, but for example, 1 to 10 g / m² ２ It is often the case, preferably 2 to 5 g / m ２ That is the case.

[0058] The foaming particles are those that foam when heated, and while thermal decomposition type foaming agents are also acceptable, thermally expandable microcapsules are preferred. Thermally expandable microcapsules become hollow particles with air bubbles inside their outer shell when heated. Using thermally expandable microcapsules prevents the gas generated from the foaming particles from escaping to the outside of the adhesive layer, making it easier to improve the foaming ratio, as described later.

[0059] Thermally expandable microcapsules contain volatile substances such as low-boiling point solvents within an outer resin shell. When heated, the outer resin softens, causing the encapsulated volatile substances to volatilize or expand. This expansion creates pressure that causes the outer shell to expand, increasing the particle size. The thermally decomposed blowing agent used as the foaming particle can be either an organic or inorganic blowing agent. Examples of organic blowing agents include azodicarbonamide, azodicarboxylic acid metal salts (such as barium azodicarboxylic acid), azobisisobutyronitrile, nitroso compounds such as N,N'-dinitrosopentamethylenetetramine, hydrazodicarbonamide, hydrazine derivatives such as 4,4'-oxybis(benzenesulfonyl hydrazide) and toluenesulfonyl hydrazide, and semicarbazide compounds such as toluenesulfonyl semicarbazide. Examples of inorganic blowing agents include ammonium carbonate, sodium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, and anhydrous monosodium citrate.

[0060] The average bubble diameter in the adhesive layer is preferably 70 μm or less. Keeping it 70 μm or less prevents bubbles from becoming too large and bursting. This improves the adhesive performance of the adhesive layer, thereby preventing excessively high adhesive strength after initial application or a decrease in adhesive performance after application. The average bubble diameter is preferably 60 μm or less, and more preferably 50 μm or less. While the average bubble diameter is not particularly limited, from the viewpoint of facilitating bubble formation and reducing the amount of adhesive due to the bubbles, it is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 25 μm or more. The average bubble diameter can be measured by observing the adhesive layer from the outer surface in a planar view. A 1 mm x 1 mm area from the outer surface of the adhesive layer can be observed at 200x magnification using an optical microscope (Keyence VHX-6000), and the diameter of all bubbles within that area can be measured. The average value of these measurements can then be used as the average bubble diameter.

[0061] The foaming ratio of the adhesive layer is preferably 1.5 times or more. A foaming ratio of 1.5 times or more improves the packaging performance of the adhesive tape. Furthermore, the thickness of the adhesive layer can be sufficiently increased by the bubbles, allowing for a reduction in the amount of adhesive in the adhesive layer while maintaining adhesive performance. From this viewpoint, a foaming ratio of 1.8 times or more is more preferable, and 2.0 times or more is even more preferable. While a higher foaming ratio is better from the viewpoint of reducing the amount of adhesive, from the viewpoint of adhesive performance, a ratio of 3.2 times or less is preferable, 3.0 times or less is more preferable, 2.8 times or less is even more preferable, and 2.4 times or less is particularly preferable. Note that the foaming ratio is an index representing the increase in the thickness of the adhesive layer due to bubbles. Specifically, the foaming ratio can be calculated by determining the increase in the thickness of the adhesive layer due to bubbles by a compression test as shown in the examples described later, determining the thickness of the unfoamed adhesive layer and the foamed adhesive layer based on that thickness increase, and then dividing the thickness of the foamed adhesive layer by the thickness of the unfoamed adhesive layer.

[0062] (Applications and Method of Use) The adhesive tape of the present invention is not particularly limited, but is preferably made into a roll. When made into a roll, the adhesive layer comes into contact with the release layer on the back of the adhesive tape. The adhesive tape of the present invention is not particularly limited, but is preferably used for sealing packaging materials, and more preferably for sealing the inside of corrugated cardboard. As described above, the adhesive tape of the present invention does not cause cracking of the sealant layer, so even when the adhesive tape is unfolded from a roll, for example, the release agent and sealant layer do not transfer to the adhesive surface during unfolding, thus maintaining good adhesive strength. For this reason, the adhesive tape of the present invention can be stored in a roll for a long period of time. In addition, because the adhesive tape of the present invention has a light unfolding force, it is easy to handle when used for sealing the inside of packaging materials, for example, and can improve the efficiency of sealing work.

[0063] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples.

[0064] [Various Physical Properties] Various physical properties were measured and evaluated using the following methods.

[0065] (Gel fraction of the sealant layer) In each example, comparative example, and reference example, when the sealant layer was prepared (coated), a portion of the coating solution was taken and dried into a sheet to prepare a test piece for measuring the gel fraction, and the mass A (mg) of the test piece was accurately weighed. Next, this test piece was immersed in 50 mL of water and left in a 60°C oven environment for 24 hours, then filtered through a 200 mesh wire mesh to collect the insoluble matter on the wire mesh, vacuum dried, and the mass B (mg) of the insoluble matter was accurately weighed. From the obtained value, the gel fraction (mass %) was calculated using the following formula. Note that the test piece was taken uniformly along the thickness direction of the sealant layer. Gel fraction (mass %) = 100 × (B / A)

[0066] (Expansion ratio measured by compression test) A 50m length of adhesive tape was wound around a cylindrical core (outer diameter 80mm) to form a wound body. As shown in Figure 2, a cylindrical fixing part 51 was passed inside the core of the obtained wound body 50, and a movable part 52 was pressed against the outer surface of the wound body 50. The movable part 52 was pressed radially inward, compressing the wound body 50 along the radial direction. Tensilon "RTC-1310A" (manufactured by ORIENTEC) was used to compress the wound body 50. In the graph (distance moved (x axis) vs. load (y axis)) when the wound body 50 was compressed, the tangent line at the point where the slope of the tangent line became constant was extended, and the value of x at the intersection with the x axis was calculated as the thickness (A) of the wound body including air bubbles. Subsequently, the same procedure was performed on a bubble-free tape sample. The thickness of the bubble-free winding (B) was measured at the calculated intersection point. By subtracting thickness (B) from thickness (A), the increase in thickness due to the bubbles in the winding was calculated, and this was divided by the number of layers of tape to obtain the increase in thickness due to bubbles per tape. The foaming ratio was calculated by taking the thickness of the adhesive layer of the bubble-free tape sample as the thickness of the unfoamed adhesive layer, adding the increase in thickness to the thickness of the unfoamed adhesive layer to obtain the thickness of the foamed adhesive layer, and then dividing the foaming ratio by the thickness of the foamed adhesive layer. Note that a bubble-free tape sample is a sample obtained when adhesive tape is made using the same method as in each example and comparative example, except that water is not coated or impregnated into the substrate.

[0067] (Average bubble diameter) For the adhesive tape, a 1 mm x 1 mm area from the outer surface of the adhesive layer was observed at 200x magnification using an optical microscope (Keyence Corporation "VHX-6000"), and the diameter of all bubbles within the above area was measured. The average value of these measurements was defined as the average bubble diameter.

[0068] (Layer Cracking) When measuring the unfolding force described later, when adhesive tape B described later was peeled off adhesive tape A described later, layer cracking was evaluated based on the following evaluation criteria. A: The sealing layer constituting adhesive tape A did not crack between the start of peeling of adhesive tape B and the completion of the peeling. B: The sealing layer constituting adhesive tape A cracked between the start of peeling of adhesive tape B and the completion of the peeling.

[0069] (Expansion Force) The dimensions of the adhesive tape were adjusted to 50 mm x 150 mm and designated as adhesive tape A. Adhesive tape A was fixed to an acrylic plate having the same dimensions as adhesive tape A using commercially available double-sided adhesive tape, and another adhesive tape B was attached to the side of the fixed adhesive tape A with the release layer (i.e., the back side of adhesive tape A) via the adhesive layer of adhesive tape B. For the attachment of adhesive tape B, a piece of adhesive tape B with the same width as adhesive tape A, 50 mm wide and 150 mm long, was taken as a test piece, one end was folded by 12 mm so that the adhesives would come into contact with each other to form a tab, and the other end was attached to the back side of the tape to be tested, and then pressed down by passing a 2 kg roller back and forth twice in the vertical direction. After that, with a 20 kg weight placed on top of adhesive tape B, it was left to stand in an oven pre-set to 60°C for one day. After standing, the laminate of adhesive tapes A and B was cut to a width of 24 mm. The peeling force measured when adhesive tape B was peeled at a peeling angle of 180° and a peeling speed of 60 m / min under conditions of 23°C and 50 RH was defined as the unfolding force. For adhesive tape B, Sekisui Chemical Co., Ltd.'s "Vinyl Cloth Tape No. 750A," which has an SP adhesive strength of approximately 25 N / 24 mm, was used. The unfolding force was evaluated based on the measured values ​​obtained by the above method. The evaluation criteria are as follows: AA: 3 N / 24 mm or less A: Greater than 3 N / 24 mm and 10 N / 24 mm or less B: Greater than 10 N / 24 mm

[0070] (Packaging Performance) A commercially available cardboard box with dimensions of 400 mm x 320 mm x 300 mm and a flap butt joint length of 400 mm was prepared. A 50 mm wide adhesive tape was applied to the flap butt joint of the cardboard box at 25°C using the I method and pressed down with 100 g / 50 mm pressure. After leaving it for 24 hours at an ambient temperature of 25°C and humidity of 50% RH, the peel rate was measured and evaluated according to the following evaluation criteria. The peel rate is the ratio of the area of ​​the peeled portion to the adhesive tape used. Note that packaging performance was not evaluated in Comparative Example 1. AA: Peel rate of 10% or less A: Peel rate of more than 10% and 30% or less B: Peel rate of more than 30%

[0071] (Bio-basedness) The bio-basedness of the sealant layer was measured in accordance with ASTM D6866.

[0072] [Ingredients Used] The ingredients used in each example, comparative example, and reference example are as follows.

[0073] (Polymers for sealing) <Polymers containing hydroxyl groups> - Oxidized starch (Oji Corn Starch Co., Ltd. "Ace A", Mw = 63000) - Oxidized starch (Oji Corn Starch Co., Ltd. "Ace C", Mw = 31000) - Hydroxypropyl starch (Oji Corn Starch Co., Ltd. "Gelpro F107E") - PVA resin (Nippon Vinegar Vipoval Co., Ltd. "JC17")

[0074] <Other polymers> ・LDPE (Suntech L2340 manufactured by Asahi Kasei Corporation)

[0075] (Crosslinking agents) Polyamide epichlorohydrin resin (Seikosha "WS4030"), water-based isocyanate crosslinking agent (Tosoh Corporation "Aquanate 105"), water-based bisphenol A epoxy resin (Daito Sangyo Co., Ltd. "Daitosizer DT571W"), water-based zirconium compound (Nippon Light Metal Co., Ltd. "Baycoat 20"), zirconium carbonate ammonium

[0076] (Release agents) ・Water-based release agent: Long-chain alkyl release agent (Rezem T-738, manufactured by Chukyo Oils Co., Ltd.) ・Solvent-based release agent: Long-chain alkyl release agent (Piroyl 1010, manufactured by Lion Specialty Chemicals) ・Solvent-free silicone release agent (KNS-3051, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0077] (Paper base material) Kraft paper: 73 g / m² basis weight with Kurupack processing and wet strength processing. ２ Unbleached kraft paper

[0078] (Adhesive Layer) Adhesive compositions for forming the adhesive layer were prepared: Adhesive composition 1 for synthetic rubber-based adhesives and Adhesive composition 2 for natural rubber-based adhesives. Adhesive composition 1 was prepared by mixing the components shown in Table 1 in the proportions shown in Table 1.

[0079] Adhesive composition 2 was prepared by mixing the components shown in Table 2 in the proportions shown in Table 2.

[0080]

[0081] [Example 1] Basis weight 70 g / m² ２ One side of a paper base made of kraft paper has a basis weight of 4 g / m². ２ A mixture of oxidized starch and a crosslinking agent was applied and dried at 110°C for 3 minutes to form a sealant layer. The composition of the mixture for forming the sealant layer was 5 parts by mass of crosslinking agent to 100 parts by mass of oxidized starch, based on solid content. A water-based release agent was applied to the sealant layer, and the basis weight after drying was 0.4 g / m². ２ The material was applied and dried to form a release layer. Next, adhesive composition 1 was applied to the surface of the substrate opposite to the surface where the release layer and sealant layer were formed, resulting in a basis weight of 26 g / m². ２ A synthetic rubber-based adhesive layer was formed to obtain an adhesive tape. The composition of the adhesive tape and the measurement results are shown in Table 3.

[0082] [Example 2] An adhesive tape was obtained in the same manner as in Example 1, except that the composition of the mixed solution for forming the sealing layer was changed to 0.3 parts by mass of crosslinking agent per 100 parts by mass of oxidized starch, based on solid content.

[0083] [Example 3] On one side of a paper substrate, oxidized starch and a crosslinking agent were applied separately, with a total basis weight of 4 g / m². ２ An adhesive tape was obtained in the same manner as in Example 1, except that the sealant layer was formed by applying the sealant in the same manner. In forming the sealant layer, first oxidized starch was applied to one side of the paper substrate, dried, and then 2 g / m of a 10% crosslinking agent was applied. ２ The mixture was applied to a certain extent and then dried at 110°C for 3 minutes. The amount applied was adjusted so that the crosslinking agent was 5 parts by mass per 100 parts by mass of oxidized starch.

[0084] [Examples 4-11] Adhesive tapes were obtained in the same manner as in Example 1, except that the types of polymers having hydroxyl groups, crosslinking agents, and release agents were changed as shown in Tables 3 and 4.

[0085]

[0086]

[0087] [Example 12] An adhesive tape was obtained in the same manner as in Example 1, except that adhesive composition 1 was replaced with adhesive composition 2, and adhesive composition 2 was applied and dried so that the basis weight after drying was as shown in Table 5, thereby forming a natural rubber-based adhesive layer.

[0088] [Example 13] After the paper substrate was left to stand for 30 minutes or more under conditions of 40°C and 90% RH, adhesive composition 1 was applied to the PET separator, resulting in a basis weight of 26 g / m². ２ A synthetic rubber-based adhesive layer was formed and then transferred to a paper substrate. The resulting adhesive tape was placed in a drying box and heated at 150°C for 15 seconds to evaporate the water and foam the adhesive layer.

[0089] [Comparative Example 1, Reference Example 1] An adhesive tape was obtained in the same manner as in Example 1, except that a crosslinking agent was not used when forming the sealing layer, and the type of polymer having hydroxyl groups was changed as shown in Table 5. In Reference Example 1, a PE laminate was used as the sealing layer.

[0090] *The basis weight of the sealant in each example and comparative example is the coating amount after drying.

[0091] As is clear from the results above, the adhesive tapes produced in the examples had cross-linked polymers containing hydroxyl groups in the sealant layer, and therefore, similar to the adhesive tape produced in Reference Example 1, they did not experience cracking of the sealant layer and were able to maintain good adhesive strength. Furthermore, they were also able to maintain good unfolding strength. In particular, in Examples 1 to 6 and 9 to 13, a water-based release agent was used as the release agent. Although the water that diluted the release agent came into contact with the sealant layer at a high temperature during the evaporation process, the sealant layer did not dissolve. Therefore, even when a water-based release agent was used, cracking of the sealant layer did not occur, and good unfolding strength was maintained. In contrast, the adhesive tapes produced in the comparative examples did not have cross-linked polymers containing hydroxyl groups in the sealant layer. Therefore, when the water-based release agent dried, the hot water caused dissolution of the sealant layer, resulting in cracking and an inability to maintain good adhesive strength. Furthermore, they were also unable to maintain good unfolding strength.

[0092] 10 Adhesive tape 11 Release layer 12 Sealing layer 13 Paper substrate 14 Adhesive layer 50 Winding body 51 Fixing part 52 Movable part A, B Thickness

Claims

An adhesive tape comprising a paper substrate, an adhesive layer provided on one side of the paper substrate, a release layer provided on the other side of the paper substrate, and a sealant layer provided between the paper substrate and the release layer, The sealing layer contains a polymer having hydroxyl groups, An adhesive tape in which the polymer having the hydroxyl group is crosslinked. 　 The adhesive tape according to claim 1, wherein the polymer having hydroxyl groups is starch. 　 The adhesive tape according to claim 1 or 2, wherein the polymer is crosslinked with a crosslinking agent, and the crosslinking agent is an aqueous crosslinking agent. 　 The adhesive tape according to claim 1 or 2, wherein the polymer is crosslinked with a crosslinking agent, and the crosslinking agent is an epoxy group-containing crosslinking agent or an isocyanate crosslinking agent. 　 The adhesive tape according to claim 1 or 2, wherein the gel fraction of the sealing agent layer is 10% by mass or more. 　 The dry coating amount of the aforementioned sealant layer is 2 g / m². ２ 30g / m or more ２ The adhesive tape according to claim 1 or 2, which is as follows: 　 The adhesive tape according to claim 1 or 2, wherein the release layer contains a water-based release agent. 　 The adhesive tape according to claim 7, wherein the aqueous release agent is a non-silicone release agent. 　 The adhesive tape according to claim 1 or 2, wherein the adhesive layer comprises a rubber-based adhesive. 　 The adhesive tape according to claim 9, wherein the rubber-based adhesive contains natural rubber. 　 The adhesive tape according to claim 1 or 2, wherein the adhesive layer has air bubbles inside. 　 The adhesive tape according to claim 11, wherein the foaming ratio of the adhesive layer measured by a compression test is 1.5 times or more. 　 The adhesive tape according to claim 11, wherein the average bubble diameter of the bubbles contained in the adhesive layer is 70 μm or less.

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