Skin adhesives and adhesive tapes

Abstract

To provide an adhesive tape for skin application having both excellent adhesion to the skin but no adhesive residue on the skin when peeled off and excellent moisture permeability, which does not cause skin problems such as skin rash or irritation due to moisture and has water resistance so that the tape does not peel off from the skin or a base material without decrease in adhesive strength after application and to provide an adhesive for forming the adhesive tape for skin application.SOLUTION: There is provided an adhesive for skin application which comprises an acrylic copolymer (A) of a monomer mixture containing a specific amount of each of an alkyl (meth)acrylate monomer having an alkyl group having 4 to 8 carbon atoms (a-1), an alkoxyalkyl (meth)acrylate monomer (a-2), a vinyl monomer having an amide group (a-3), a vinyl monomer having an acid group (a-4) and a vinyl monomer having a hydroxyl group (a-5), wherein [(a-4) / (a-5)] is 5 to 300.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive and an adhesive tape, and more particularly to an adhesive and an adhesive tape that are suitable for application to the skin. [Background technology]

[0002] Adhesive tapes (hereinafter sometimes referred to as skin adhesive sheets) used for attachment to the skin, such as adhesive bandages, surgical tapes, poultices, plasters, sheets for fixing electrodes for electrocardiogram measurement, etc., have an adhesive layer formed on a substrate using an adhesive composition.

[0003] The adhesive layer of a skin patch sheet is required to adhere well to the skin, preventing external water, bacteria, viruses, etc. from entering the body through high adhesive strength, while also being breathable to allow moisture from sweating to evaporate. If breathability is poor, sweat will accumulate between the skin and the adhesive layer at the site where the skin patch sheet is attached, making the skin more susceptible to skin disorders such as rashes and stuffiness (skin irritation), and the adhesive strength will be reduced, making the tape more likely to peel off from the skin (water resistance), or causing the sheet to peel off to its back when it is applied multiple times (water resistance to the back surface). However, if the adhesive strength is too strong to prevent peeling, the hair on the body surface may be torn off when the patch is removed, causing keratin peeling, or the adhesive may remain on the skin. Therefore, it is also required that the adhesive be less painful when removed and that the adhesive not remain on the skin (residual adhesive on the skin).

[0004] Patent Document 1 discloses a medical adhesive tape for application to the skin with improved moisture permeability, which is obtained by irradiating a pressure-sensitive adhesive layer of a specific composition with ionizing radiation to adjust the gel fraction in the adhesive layer to a certain value or more, thereby achieving excellent skin adhesion and internal cohesion. The adhesive tape is a copolymer consisting of 40 to 80% by weight of an acrylic acid alkyl ester monomer, 10 to 50% by weight of an alkoxy group-containing ethylenically unsaturated monomer, and 1 to 10% by weight of a carboxyl group-containing ethylenically unsaturated monomer.

[0005] Patent Document 2 discloses a medical adhesive that has high water vapor permeability, is difficult to peel off, has appropriate adhesive strength that does not damage the skin when peeled off, has appropriate adhesive strength durability, and has appropriate cohesive strength. The medical adhesive contains a polymer that contains more than 50% by weight of units derived from an alkoxyalkyl acrylate, and the glass transition temperature (Tg) of the homopolymer is −35° C. or lower.

[0006] Patent Document 3 discloses a medical patch that has excellent skin adhesion and internal cohesion by using a pressure-sensitive adhesive layer mainly made of a copolymer of a specific composition with a gel fraction of substantially 0% by weight, and that is made of 40 to 80% by weight of an acrylic acid alkyl ester monomer, 10 to 50% by weight of an alkoxy group-containing ethylenically unsaturated monomer, and 1 to 10% by weight of a carboxyl group-containing ethylenically unsaturated monomer, with a gel fraction of substantially 0% by weight and a weight-average molecular weight of 1,000,000 or more.

[0007] Patent Document 4 discloses adhesives that exhibit high moisture permeability and good adhesive strength, have good adhesion to the skin, are tactile when applied, and are less likely to cause pain when removed, such as 5 to 45 wt % alkyl (meth)acrylate, 0.01 to 10 wt % hydroxyl group-containing (meth)acrylate or hydroxyl group-containing allyl ether, 50 to 78 wt % alkoxyalkyl (meth)acrylate, 1 to 25 wt % alkoxypolyalkylene glycol mono(meth)acrylate or alkoxypolyalkylene glycol allyl ether, and a copolymer made of a monomer having an amide bond.

[0008] Patent Document 5 discloses a copolymer containing 5 to 49% by weight of alkyl (meth)acrylate, 0.01 to 10% by weight of a (meth)acrylate having a hydroxyl group or an allyl ether having a hydroxyl group, and 50 to 80% by weight of an alkoxyalkyl (meth)acrylate, as an adhesive that exhibits high moisture permeability and good resistance to keratin peeling and has excellent adhesion to olefin-based substrates.

[0009] Furthermore, skin patch sheets often use a polyurethane substrate that is stretchable, conformable, highly moisture-permeable, and highly waterproof, and the adhesive layer is required to have strong adhesion to the polyurethane substrate and water resistance on its back surface in addition to the aforementioned performance on the skin. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 11-226109 [Patent Document 2] Japanese Patent Application Publication No. 7-275340 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-104467 [Patent Document 4] Japanese Patent Application Publication No. 2017-095598 [Patent Document 5] Japanese Patent Application Publication No. 2017-206586 Summary of the Invention [Problem to be solved by the invention]

[0011] As described above, when a water-soluble monomer, which is a highly moisture-permeable material, is used to increase the moisture permeability of an adhesive tape, moisture can pass through and there is no rash or itchiness. However, it is difficult to adjust the adhesion to the skin and cohesive strength, which can result in low adhesion to the skin or the occurrence of adhesive residue on the skin. Furthermore, if a material with even higher moisture permeability is used, the adhesive layer will absorb water and swell, reducing its adhesive strength and causing the adhesive to peel off from the skin or its back surface. The adhesive tapes of Patent Documents 1 to 3 lack adhesive strength, and the adhesive tapes of Patent Documents 4 and 5 do not achieve both moisture permeability and water resistance.

[0012] That is, it is difficult to achieve both moisture permeability and adhesive strength, and there is a demand for adhesives and adhesive tapes that can achieve both of these properties. Therefore, the problem that the present invention aims to solve is to provide an adhesive tape for application to the skin, which has excellent adhesive strength that has high adhesion to the skin but does not leave any adhesive residue on the skin when removed (skin adhesive residue resistance), does not cause skin disorders such as rash or stuffiness due to moisture (skin irritation), does not lose adhesive strength even after application, and has water resistance that prevents the tape from peeling off from the skin or substrate, and which also has excellent moisture permeability, as well as an adhesive for forming said adhesive tape for application to the skin. Furthermore, the present invention aims to provide a pressure-sensitive adhesive that has excellent adhesion to a substrate, even if the substrate is a polyurethane substrate such as a urethane sheet or a urethane nonwoven fabric, without impairing the moisture permeability of the polyurethane substrate, and that can thereby form a pressure-sensitive adhesive tape that also has excellent water resistance on its back surface. [Means for solving the problem]

[0013] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, an embodiment of the present invention relates to an adhesive for application to skin, comprising an acrylic copolymer (A) and a curing agent (C), wherein the acrylic copolymer (A) is a copolymer of a monomer mixture containing 10 to 80 mass% of an alkyl (meth)acrylate monomer (a-1) having an alkyl group with 4 to 8 carbon atoms, 15 to 50 mass% of an alkoxyalkyl (meth)acrylate monomer (a-2), 0.1 to 20 mass% of a vinyl monomer having an amide group (a-3), 0.1 to 5 mass% of a vinyl monomer having an acid group (a-4), and 0.01 to 1 mass% of a vinyl monomer having a hydroxyl group (a-5), and wherein the mass ratio of the vinyl monomer having a hydroxyl group (a-5) to the vinyl monomer having an acid group (a-4), [(a-4) / (a-5)], is 5 to 300.

[0014] Furthermore, an embodiment of the present invention relates to the pressure-sensitive adhesive for application to skin, wherein the curing agent (C) is at least one of an isocyanate compound and an epoxy compound.

[0015] Furthermore, an embodiment of the present invention relates to the pressure-sensitive adhesive for application to skin, wherein the content of the curing agent (C) is 0.01 to 5 parts by mass per 100 parts by mass of the acrylic copolymer (A).

[0016] Another embodiment of the present invention relates to the above-mentioned adhesive for application to skin, further comprising a tackifier (B).

[0017] Another embodiment of the present invention relates to an adhesive tape having an adhesive layer formed on a substrate from the above adhesive for application to skin.

[0018] Furthermore, an embodiment of the present invention relates to the above-mentioned pressure-sensitive adhesive tape, wherein the substrate is at least one of a urethane sheet and a urethane nonwoven fabric. [Effects of the Invention]

[0019] The adhesive and adhesive tape obtained by the present invention, when used for skin application, have high moisture permeability, good adhesive strength, and durability to skin application, and are unlikely to cause skin disorders such as stuffiness and rashes. Furthermore, when peeled from the skin, there is little pain, no keratin peeling occurs, and no adhesive residue remains. Furthermore, they follow the movement of the skin when applied, providing a comfortable, comfortable feeling. Furthermore, they have high moisture permeability and water resistance, and are difficult to peel off even when wet. Furthermore, even when the substrate is a polyurethane substrate such as a urethane sheet or urethane nonwoven fabric, it is possible to provide a pressure-sensitive adhesive that can achieve low skin irritation, low skin adhesive residue, skin adhesion, and water resistance, as well as conformability to the polyurethane substrate, adhesion, and water resistance on its back surface, and that has excellent adhesion to the substrate without impairing the moisture permeability of the polyurethane substrate, thereby allowing the formation of a pressure-sensitive adhesive tape that also has excellent water resistance on its back surface. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail below, but it goes without saying that other embodiments are also included in the scope of the present invention as long as they conform to the spirit of the present invention. Furthermore, in this specification, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the lower and upper limit values ​​of the range. Furthermore, in this specification, "tape," "sheet," and "film" are synonyms.

[0021] In this specification, unless otherwise specified, the terms "(meth)acrylic", "(meth)acryloyl", "(meth)acrylic acid", "(meth)acrylate", "(meth)acryloyloxy", and "(meth)allyl" mean "acrylic or methacrylic", "acryloyl or methacryloyl", "acrylic acid or methacrylic acid", "acrylate or methacrylate", "acryloyloxy or methacryloyloxy", and "allyl or methallyl", respectively. Furthermore, in this specification, the alkyl(meth)acrylate monomer (a-1) having 4 to 8 carbon atoms, the alkoxyalkyl(meth)acrylate monomer (a-2), the vinyl monomer (a-3) having an amide group, the vinyl monomer (a-4) having an acid group, the vinyl monomer (a-5) having a hydroxyl group, and the other monomer (a-6) may be referred to as the monomer (a-1), the monomer (a-2), the monomer (a-3), the monomer (a-4), the monomer (a-5), and the monomer (a-6), respectively. Unless otherwise noted, the various components appearing in this specification may be used independently either alone or in combination of two or more.

[0022] <<Skin adhesive>> The adhesive for application to skin of the present invention comprises a copolymer (A) of a monomer mixture containing 10 to 80 mass% of an alkyl(meth)acrylate monomer (a-1) having an alkyl group with 4 to 8 carbon atoms, 15 to 50 mass% of an alkoxyalkyl(meth)acrylate monomer (a-2), 0.1 to 20 mass% of a vinyl-based monomer (a-3) having an amide group, 0.1 to 5 mass% of a vinyl-based monomer (a-4) having an acid group, and 0.01 to 1 mass% of a vinyl-based monomer (a-5) having a hydroxyl group, wherein the mass ratio of the vinyl-based monomer (a-5) having a hydroxyl group to the vinyl-based monomer (a-4) having an acid group [(a-4) / (a-5)] is 5 to 300. By including such a copolymerized tower body (A), it is possible to obtain an adhesive for application to skin that has both moisture permeability and adhesive strength. The adhesive for application to skin may further contain a tackifier (B), a curing agent (C) or other additives, if necessary.

[0023] <Acrylic copolymer (A)> The acrylic copolymer (A) is a copolymer of a monomer mixture containing 10 to 80 mass% of alkyl (meth)acrylate monomers (a-1) having an alkyl group with 4 to 8 carbon atoms, 15 to 50 mass% of alkoxyalkyl (meth)acrylate monomers (a-2), 0.1 to 20 mass% of vinyl monomers (a-3) having an amide group, 0.1 to 5 mass% of vinyl monomers (a-4) having an acid group, and 0.01 to 1 mass% of vinyl monomers (a-5) having a hydroxyl group, and the mass ratio of the vinyl monomers (a-5) having a hydroxyl group to the vinyl monomers (a-4) having an acid group [(a-4) / (a-5)] is 5 to 300.

[0024] In order to achieve a good balance of adhesiveness, moisture permeability, water resistance, self-backside water resistance, skin adhesion, and skin peelability (pain, keratin peeling), it is necessary to blend and copolymerize the monomers (a-1) to (a-5) in a balanced manner. In particular, adhesive tapes for application to the skin may become wet, and a certain degree of hydrophobicity is required to prevent water from penetrating through the interface between the adhesive tape and the skin and to prevent the tape from peeling off from the skin. For this reason, it is necessary to blend and copolymerize the monomers (a-1) to (a-5), which differ in hydrophilicity or polarity (moisture permeability, crosslinkability, adhesiveness, etc.) and hydrophobicity or non-polarity (water resistance, adhesiveness, etc.), at the above-mentioned content ratios.

[0025] The monomer mixture may further contain another monomer (a-6) copolymerizable with the monomer (a-1), the monomer (a-2), the monomer (a-3), the monomer (a-4), and the monomer (a-5).

[0026] The acrylic copolymer (A) preferably has a glass transition temperature (Tg) calculated by the Fox equation of −70° C. to 0° C., more preferably −60° C. to −25° C. By using a (meth)acrylic copolymer having such a glass transition temperature, it is possible to obtain an adhesive that has excellent skin adhesion durability and reduces pain upon peeling.

[0027] [Monomer (a-1)] The monomer (a-1) is an alkyl(meth)acrylate monomer having an alkyl group having 4 to 8 carbon atoms. Examples of the monomer (a-1) include alkyl (meth)acrylates such as n-butyl (meth)acrylate, isobutyl (meth)acrylate, tertiary butyl (meth), n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0028] Among these, n-butyl (meth)acrylate, in which the alkyl group has 4 carbon atoms, or 2-ethylhexyl (meth)acrylate, in which the alkyl group has 8 carbon atoms, is preferred, and more preferably 2-ethylhexyl (meth)acrylate, in which the alkyl group has 8 carbon atoms, is preferred from the standpoint of adhesive strength and water resistance of the back surface.

[0029] The content of the monomer (a-1) is 10 to 80 mass %, preferably 20 to 70 mass %, and more preferably 30 to 60 mass %, based on 100 mass % of the total monomer mixture constituting the copolymer. By being in this range, moisture permeability and water resistance can be imparted without impairing adhesive strength.

[0030] [Monomer (a-2)] Monomer (a-2) is an alkoxyalkyl (meth)acrylate monomer, and is not particularly limited as long as it is a (meth)acrylate in which an alkoxyalkyl group is bonded as the alcohol-derived portion of the ester structure of the (meth)acrylate.

[0031] In view of achieving both moisture permeability and water resistance, the alkoxy group of the monomer (a-2) preferably has 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 2 carbon atoms. The alkylene group bonded to the alkoxy group preferably has 1 to 18 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 4 carbon atoms.

[0032] Examples of the monomer (a-2) include 2-methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxymethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate. Among these, 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate are preferred from the viewpoint of water resistance.

[0033] Alkoxy groups are highly hydrophilic and therefore excellent at retaining and releasing water vapor. To obtain sufficient moisture permeability, the content of monomer (a-2) is 15 to 50 mass%, preferably 25 to 50 mass%, and more preferably 35 to 45 mass%, based on 100 mass% of the total monomer mixture constituting the copolymer. Within this range, sufficient back surface water resistance can be obtained without impairing water resistance.

[0034] [Monomer (a-3)] Monomer (a-3) is a vinyl monomer having an amide group. The inclusion of monomer (a-3) increases adhesive strength, acts as a reaction catalyst with the curing agent, and contributes to stabilizing the reaction.

[0035] Examples of the monomer (a-3) include N-vinyl cyclic amides and (meth)acrylamides.

[0036] Examples of N-vinyl cyclic amides include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione.

[0037] Examples of (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide, N-hydroxyalkyl(meth)acrylamide, and N-alkoxyalkyl(meth)acrylamide.

[0038] Examples of N-alkyl(meth)acrylamides include N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, and N-octylacrylamide. The N-alkyl(meth)acrylamides also include (meth)acrylamides having an amino group, such as dimethylaminoethyl(meth)acrylamide, diethylaminoethyl(meth)acrylamide, and dimethylaminopropyl(meth)acrylamide.

[0039] Examples of N,N-dialkyl(meth)acrylamides include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide.

[0040] Examples of N-hydroxyalkyl(meth)acrylamides include N-methylol(meth)acrylamide, N-(2)-hydroxyethyl(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, and N-methyl-N-2-hydroxyethyl(meth)acrylamide.

[0041] Examples of N-alkoxyalkyl(meth)acrylamides include N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.

[0042] Among these, monomer (a-3) is preferably N-vinyl cyclic amides such as N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione, which do not have active hydrogen or other crosslinking groups, or N,N-dialkyl(meth)acrylamides such as N,N-dialkyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide. Furthermore, from the viewpoint of achieving both water resistance and moisture permeability on the back surface, N-vinyl-2-pyrrolidone and dimethylacrylamide are more preferred.

[0043] The content of monomer (a-3) is 0.1 to 20% by mass, preferably 0.5 to 10% by mass, and more preferably 1 to 8% by mass, based on 100% by mass of the total monomer mixture constituting the copolymer. By keeping it in this range, the reaction with the curing agent can be appropriately controlled, and adhesion, moisture permeability, water resistance, and backside water resistance can be improved.

[0044] [Monomer (a-4)] The monomer (a-4) is a vinyl monomer having an acid group. The acidic group of the monomer (a-4) may be a carboxyl group, a sulfonic acid group, or a phosphate group, but since it comes into contact with the skin, a carboxyl group is preferred because it has low acidity and is gentle to the skin.

[0045] Examples of vinyl monomers having a carboxyl group include (meth)acrylic acid, itaconic acid, and carboxyethyl acrylate. Among these, acrylic acid and carboxyethyl acrylate are preferred from the viewpoint of cohesive strength, as they improve adhesive residue and water resistance. Among these, carboxyethyl acrylate is preferred from the viewpoint of adhesive residue and skin irritation resistance.

[0046] The content of monomer (a-4) is 0.1 to 5 mass%, preferably 0.5 to 4 mass%, more preferably 1.0 to 3 mass%, based on 100 mass% of the total monomer mixture constituting the copolymer. This range ensures high adhesive strength, no adhesive residue when the tape is peeled off, no severe pain or keratin peeling, and improved back surface water resistance.

[0047] [Monomer (a-5)] The monomer (a-5) is a vinyl monomer having a hydroxyl group. Examples of the monomer (a-5) include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and (meth)acrylates having a hydroxyl group such as polyalkylene glycol mono(meth)acrylate, and allyl ethers having a hydroxyl group such as polyalkylene glycol allyl ether.

[0048] From the viewpoints of crosslinking speed and crosslinking density with the curing agent, and water resistance, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred.

[0049] The content of monomer (a-5) is 0.01 to 1% by mass, preferably 0.01 to 0.5% by mass, and more preferably 0.02 to 0.5% by mass, based on 100% by mass of the total monomer mixture constituting the copolymer. Monomer (a-5) reacts with the curing agent to form a crosslinked structure, so if it is 1% by mass or less, it is possible to prevent excessive crosslinking, which would otherwise cause a decrease in adhesion to the skin or water resistance on the back surface. If it is 0.01% by mass or more, it is possible to improve adhesive strength and prevent adhesive residue.

[0050] The mass ratio of the vinyl monomer (a-4) having an acid group to the vinyl monomer (a-5) having a hydroxyl group [(a-4) / (a-5)] is 5 to 300, and from the viewpoint of improving the water resistance of the back surface without leaving any adhesive residue when the tape is peeled off, without causing any severe pain or keratin peeling, it is preferably 20 to 250, and more preferably 35 to 200.

[0051] Adhesives are required to adhere firmly to substrates and leave minimal adhesive residue when removed from the skin. To achieve this, it is desirable for the coating film to have adequate cohesive strength and for the adhesive to crosslink after penetrating the substrate. From these perspectives, crosslinking with acid groups, which impart internal cohesive strength and have a relatively slow reaction rate, is desirable. However, the reaction rate is too slow with acid groups alone, so the rate can be adjusted by adding a small amount of hydroxyl groups. Therefore, if the mass ratio of the vinyl monomer (a-4) having an acid group to the vinyl monomer (a-5) having a hydroxyl group [(a-4) / (a-5)] is 5 to 300, a sufficient crosslinked structure can be formed, making it difficult for the adhesive to remain on the skin, while avoiding excessive crosslinking, ensuring adhesion to the skin and water-resistant adhesion.

[0052] [Monomer (a-6)] The monomer (a-6) is another monomer copolymerizable with the monomer (a-1), the monomer (a-2), the monomer (a-3), the monomer (a-4), and the monomer (a-5).

[0053] Examples of monomer (a-6) include alkyl(meth)acrylates having an alkyl group with 1 to 3 carbon atoms, alkyl(meth)acrylates having an alkyl group with 9 or more carbon atoms, alkoxypolyalkylene glycol mono(meth)acrylates, vinyl monomers having an alkoxypolyalkylene glycol allyl ether alicyclic structure, vinyl monomers having an aromatic ring structure, vinyl monomers having a ring structure containing a heteroatom (excluding monomer (a-3)), vinyl monomers having a polydimethylsiloxane skeleton, vinyl monomers having a perfluoroalkyl group, and macromonomers such as styrene and polymethyl methacrylate. From the viewpoint of a balance of adhesiveness, moisture permeability, and water resistance, any of these can be used, but an amount of 0 to 20 mass % is preferred.

[0054] [Method for producing acrylic copolymer (A)] The acrylic copolymer (A) can be produced by known methods, but is preferably produced by solution polymerization, in which a solvent such as methyl acetate, ethyl acetate, methyl ethyl ketone, toluene, or acetone is preferably used.

[0055] Specifically, for example, a solvent and a monomer mixture are charged into a reaction vessel, a polymerization initiator is added under an inert gas atmosphere such as nitrogen gas, and the mixture is heated to a reaction temperature of about 50 to 90°C to carry out the polymerization reaction for 4 to 20 hours.

[0056] Examples of the polymerization initiator include azo initiators and peroxide initiators. These polymerization initiators are usually used in an amount ranging from 0.01 to 5 parts by mass per 100 parts by mass of the monomer mixture. Furthermore, a chain transfer agent, raw material monomers, and a solvent may be added as appropriate during the polymerization reaction.

[0057] The mass average molecular weight of the acrylic copolymer (A) can be adjusted according to known techniques by adjusting reaction conditions such as the type and amount of the solvent used, the type and amount of the polymerization initiator, the reaction time, the reaction temperature, etc. From the viewpoint of adhesive strength and holding power, the mass average molecular weight of the acrylic copolymer (A) is preferably 200,000 to 2,000,000, and more preferably 400,000 to 1,500,000.

[0058] <Tackifier (B)> The pressure-sensitive adhesive of the present invention may contain a tackifier (B) to the extent that the problem can be solved. Preferred examples of the tackifier (B) include rosin resins, terpene resins, alicyclic hydrocarbon resins, aliphatic petroleum resins, aromatic petroleum resins, alkylphenol formaldehyde resins (oil-based phenolic resins), etc. By including the tackifier (B), it is easier to further improve adhesion to skin and water resistance.

[0059] From the viewpoints of adhesive strength to the skin and water resistance, the tackifier (B) is preferably contained in an amount of 5 to 30 parts by mass, more preferably 7 to 25 parts by mass, per 100 parts by mass of the acrylic copolymer (A).

[0060] Examples of the tackifier resin (B) include rosin-based resins, terpene-based resins, aromatic petroleum resins, and aliphatic petroleum resins. Examples of rosin-based resins include rosin esters, polymerized rosins, hydrogenated rosins, disproportionated rosins, maleic acid-modified rosins, fumaric acid-modified rosins, rosin phenolic resins, and natural rosins. Examples of terpene-based resins include α-pinene resins, β-pinene resins, dipentene resins, aromatic modified terpene resins, hydrogenated terpene resins, terpene phenolic resins, acid-modified terpene resins, and styrenated terpene resins. From the viewpoint of obtaining a desirable adhesive strength to the skin, rosin-based resins or terpene-based resins are preferred. Among terpene-based resins, terpene phenolic resins are preferred.

[0061] Specifically, for example, the polymerized rosin esters manufactured by Arakawa Chemical Industries, Ltd., such as the Pencel series, Pencel D-125 (manufactured by Arakawa Chemical Industries, Ltd., softening point 120-130), Pencel D-135 (manufactured by Arakawa Chemical Industries, Ltd., softening point 130-140), and Pencel D-160 (manufactured by Arakawa Chemical Industries, Ltd., softening point 150-165), the Pine Crystal series manufactured by Arakawa Chemical Industries, Ltd., such as the rosin ester Pine Crystal KE359 (manufactured by Arakawa Chemical Industries, Ltd., softening point 94-104) and the rosin-containing diol Pine Crystal D-6011 (manufactured by Arakawa Chemical Industries, Ltd., softening point 84-99), and the terpene phenol resins manufactured by Yasuhara Chemical Industries, Ltd., such as the YS Polyster series, YS Polyster T160 (manufactured by Yasuhara Chemical Industries, Ltd.), YS Polyster T145 (Yasuhara Chemical Co., softening point 140-150), YS Polyster T130 (Yasuhara Chemical Co., softening point 125-135), YS Polyster T115 (Yasuhara Chemical Co., softening point 110-120), YS Polyster T100 (Yasuhara Chemical Co., softening point 95-105), YS Polyster T80 (Yasuhara Chemical Co., softening point 75-85), YS Polyster U130 (Yasuhara Chemical Co., softening point 125-135), YS Polyster U115 (Yasuhara Chemical Co., softening point 110-120), and rosin esters manufactured by Air Brown include Sylvalite Examples of terpene phenol resins include, but are not limited to, Sylvares TP95 (manufactured by Air Brown, softening point 95) and Sylvares TP2019 (manufactured by Air Brown, softening point 125), and examples of terpene phenol resins include, but are not limited to, Sylvares RE85L (manufactured by Air Brown, softening point 85), Sylvalite RE100L (manufactured by Air Brown, softening point 100), and Sylvalite RE105 (manufactured by Air Brown, softening point 105). The softening point is expressed in °C.

[0062] The softening point of the tackifier (B) is preferably 75 to 140° C. When the softening point is 75 to 140° C., it becomes easy to achieve both adhesive strength and cohesive strength.

[0063] <Curing agent (C)> The pressure-sensitive adhesive of the present invention may contain a curing agent (C). Examples of the curing agent (C) for curing the copolymer include a compound having an isocyanate group (hereinafter referred to as an isocyanate-based curing agent), an epoxy compound, an aziridine compound, a metal chelate, an amine compound, etc. Among these, isocyanate compounds are preferred from the viewpoint of adhesive residue, and epoxy compounds are preferred from the viewpoint of moisture permeability.

[0064] Examples of isocyanate curing agents include compounds having two or more isocyanate groups in the molecule, such as tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate; compounds obtained by addition reaction of these with polyhydric alcohols such as trimethylolpropane and pentaerythritol; isocyanurate compounds and biuret compounds thereof; and urethane prepolymer-type compounds having two or more isocyanate groups in the molecule, obtained by addition reaction of these with known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprenes.

[0065] The type of isocyanate curing agent can be selected appropriately depending on the substrate, application, etc. Tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, compounds obtained by addition reaction of these with polyhydric alcohols such as trimethylolpropane and pentaerythritol, and their isocyanurate compounds and biuret compounds are preferably used.

[0066] Examples of epoxy compounds include bisphenol A-epichlorohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidylaminophenylmethane.

[0067] Examples of the aziridine compound include N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxite), N,N'-toluene-2,4-bis(1-aziridinecarboxite), bisisophthaloyl-1-(2-methylaziridine), tri-1-aziridinylphosphine oxide, N,N'-hexamethylene-1,6-bis(1-aziridinecarboxite), 2,2'-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethane tri-β-aziridinylpropionate, and tris-2,4,6-(1-aziridinyl)-1,3,5-triazine.

[0068] Metal chelates include, for example, aluminum, iron, copper, zinc, tin, titanium, nickel, and ammonium. Examples include coordination compounds of polyvalent metals such as chromium, magnesium, vanadium, chromium, and zirconium with acetylacetone or ethyl acetoacetate.

[0069] The content of the curing agent (C) is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, and even more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the copolymer, from the viewpoints of adhesion to the skin and water resistance on the back surface.

[0070] <Other additives> Various additives can be added to the adhesive of the present invention as desired. Examples include antibacterial agents, moisturizers, vitamins, fragrances, etc. These can be added in effective amounts as needed.

[0071] Furthermore, when the formed adhesive tape is used after sterilization using an autoclave, ethylene oxide gas, radiation, or the like, the following may be used to prevent deterioration of the adhesive due to radiation sterilization: an electron / ion scavenger such as pyrene or quinone that inactivates electrons and ions generated in the initial process of radiation irradiation; an energy transfer agent such as acenaphthene that inactivates excited species; a radical scavenger that inactivates polymer radicals such as mercaptan, octahydrophenanthrene, or monoalkyldiphenyl ether; an antioxidant that inactivates polymer radicals and peroxy radicals such as phenolic antioxidants, organic thioacid salts, phosphite triesters, or BHT; or a plasticizer that inactivates polymer radicals such as phthalate esters, epoxy plasticizers, or chlorinated paraffins.

[0072] The pressure-sensitive adhesive of the present invention may be diluted with a solvent to facilitate application. Known solvents can be used, such as ethyl acetate, acetone, methyl ethyl ketone, and toluene.

[0073] Adhesive tape The adhesive tape has an adhesive layer formed from the adhesive for application to the skin of the present invention, and is used for application to the skin such as bandages, surgical tapes, poultices, plasters, or sheets for fixing electrodes for electrocardiogram measurement. The adhesive tape preferably comprises a substrate and an adhesive layer formed from the adhesive of the present invention. Alternatively, a double-sided adhesive tape having adhesive layers on both sides of a core material, or a cast adhesive tape consisting only of an adhesive layer without a substrate or core material, is also preferred. The adhesive layer can be formed by coating the adhesive on a release sheet, drying it to form an adhesive layer, and then laminating the substrate. Alternatively, the adhesive can be formed by coating the adhesive on a substrate and drying it. If a high temperature is required for the crosslinking reaction, heating is performed during or after drying. Furthermore, providing perforations in the adhesive tape can improve breathability. The adhesive tape may be sterilized by autoclave, ethylene oxide gas, radiation, or the like before use.

[0074] <Base material> The substrate is not particularly limited, but major examples include woven fabrics, nonwoven fabrics, knitted fabrics made of rayon, cotton, polyester yarn, etc. alone or with polyurethane yarn inserted, and films or sheets made of synthetic resins such as plasticized soft polyvinyl chloride, unplasticized soft polyvinyl chloride, polyethylene, polypropylene, polybutene, ethylene-methyl methacrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-propylene rubber, polyamide, polyethylene terephthalate, polyurethane, polyvinylidene chloride, polyvinyl alcohol, etc. Flexible films or sheets such as plastic foam sheets, cellulose, cellulose acetate, etc. can also be used. These substrates may be subjected to corona discharge treatment, etc., if necessary. When a substrate having excellent moisture permeability is used, the excellent moisture permeability of the pressure-sensitive adhesive of the present invention can be fully exhibited.

[0075] Among these, polyurethane substrates such as urethane sheets or urethane nonwoven fabrics are preferred, as they have stretchability, conformability, high moisture permeability, and excellent waterproofness. The pressure-sensitive adhesive of the present invention has excellent adhesiveness, and therefore, even when the substrate is a polyurethane substrate, the moisture permeability is not impaired and the back surface has good water resistance. [Example]

[0076] The present invention will be described in detail below with reference to examples and comparative examples. In the following examples, unless otherwise specified, "parts" means parts by mass, "%" means % by mass, and "RH" means relative humidity. The blend amounts in the table are in parts by mass, and values ​​other than the solvent are calculated as non-volatile content. Note that blank spaces in the table indicate that no blend was made. The mass average molecular weight (Mw) of the copolymer was measured by the following method.

[0077] <Mass average molecular weight (Mw)> Mw was measured under the following conditions: Mw was determined by a calibration curve method using polystyrene with a known mass average molecular weight as a standard substance. Device name: Shimadzu Corporation, LC-GPC system "Prominence" Column: Two TSKgel α-M columns manufactured by Tosoh Corporation connected in series. Mobile phase solvent: tetrahydrofuran Flow rate: 1.0ml / min Column temperature: 40℃

[0078] The abbreviations for the materials used in the following examples are shown below. <Monomer> [Monomer (a-1)] BA: n-butyl acrylate 2-EHA: 2-ethylhexyl acrylate [Monomer (a-2)] MEA: Methoxyethyl acrylate ·MEMA: Methoxyethyl methacrylate BEA: n-butoxyethyl acrylate EEA: Ethoxyethyl acrylate [Monomer (a-3)] NVP: N-vinylpyrrolidone ACMO: Acryloylmorpholine DMAAm: N,N-dimethylaminoethylacrylamide [Monomer (a-4)] AA: Acrylic acid βCEA: 2-carboxyethyl acrylate [Monomer (a-5)] 2-HEA: 2-hydroxyethyl acrylate 4-HBA: 4-hydroxybutyl acrylate [Monomer (a-6)] INA: Isononyl acrylate LA: Lauryl acrylate ·LA: Lauryl acrylate MPE400A: Methoxypolyethylene glycol acrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.

[0079] <Curing agent (C)> TY-20: Mitsui Chemicals Takenate TY-20 (non-volatile content 75%), trimethylolpropane-m-xylylene diisocyanate adduct TETRAD: TETRAD-X, N,N,N',N'-tetraglycidyl-m-xylenediamine, manufactured by Mitsubishi Gas Chemical Company, Inc. <Tackifier (B)> D-125: Arakawa Chemical Co., Ltd.'s Pencel D-125, a rosin-based tackifier

[0080] <Production of acrylic copolymer> (Production of Acrylic Copolymer (A-1)) A four-necked flask equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping funnel was charged with 53.48 parts by mass of n-butyl acrylate, 40.00 parts by mass of methoxyethyl acrylate, 5 parts by mass of N-vinylpyrrolidone, 1.50 parts by mass of acrylic acid, and 0.02 parts by mass of 2-hydroxyethyl acrylate, 66 parts of ethyl acetate, and 0.2 parts by mass of azobisisobutyronitrile. The flask was heated to 80 ° C. while introducing nitrogen gas. The remaining half was charged into the dropping funnel and added dropwise at 80 ° C. under a nitrogen atmosphere for 1.5 hours. The polymerization reaction was then carried out for 5.5 hours at 80 ° C. under a nitrogen atmosphere. After completion of the reaction, 32 parts by mass of ethyl acetate was added to dilute the mixture, and an acrylic copolymer (A-1) solution with a nonvolatile content of 50% by mass and a weight average molecular weight of 600,000 was obtained.

[0081] (Preparation of Acrylic Copolymer (A-2 to 22) and (A'-1 to 21) Solutions) Solutions of acrylic copolymers (A-2 to 22) and (A'-1 to 21) were produced in the same manner as the acrylic copolymer (A-1) solution, except that the materials, compositions, and blending amounts (parts by mass) were changed to those shown in Tables 1 to 4.

[0082] [Table 1]

[0083] [Table 2]

[0084] [Table 3]

[0085] [Table 4]

[0086] Example 1 To 100 parts by mass of the nonvolatile content of the obtained acrylic copolymer (A-1), 1.5 parts by mass of Takenate D-110N was added as a curing agent (C) in terms of nonvolatile content, and the nonvolatile content was adjusted to 50% by mass with ethyl acetate to obtain an adhesive for application to the skin.

[0087] (Examples 2 to 23, Comparative Examples 1 to 21) Each adhesive for application to the skin was obtained in the same manner as in Example 1, except that the materials, compositions, and blending amounts (parts by mass) were changed to those shown in Tables 1 to 4.

[0088] <Measurement and evaluation of adhesive tape properties> Using the obtained adhesive for application to skin, an adhesive tape was produced according to the following method. (1) Adhesive tape x 1 (for adhesive strength evaluation) The adhesive for application to skin obtained above was coated onto a 25 μm thick polyester film (trade name "E5100", manufactured by Toyobo Co., Ltd.) so that the thickness after drying would be 25 μm, and then dried in a hot air oven at 100° C. for 2 minutes. After drying, the film was laminated onto a 38 μm thick polyester separator (trade name "Superstic" SP-PET38, manufactured by Lintec Corporation) and further aged at 50° C. for 4 days to obtain adhesive tape X1.

[0089] (2) Adhesive tape x 2 (for evaluating moisture permeability, skin adhesion, water resistance, water resistance on the back side, and adhesive residue) The adhesive for skin application was applied to a 38 μm thick polyester separator (trade name "Superstick" SP-PET38, manufactured by Lintec Corporation) so that the thickness after drying would be 25 μm, and then dried in a hot air oven at 100°C for 2 minutes. After drying, a 38 μm thick moisture-permeable polyurethane sheet (moisture permeability 2,500 g / m) was placed on the separator. 2 The adhesive tape X2 was obtained by laminating the adhesive tape X1 onto the adhesive tape X2 for 24 hours and then curing the adhesive tape X2 for 4 days at 50°C.

[0090] <Adhesive strength> The resulting adhesive tape X1 was cut into a size of 25 mm wide and 100 mm long to serve as a measurement sample. The polyester separator was then peeled off from the sample in an environment of 23°C and 50% RH, and the exposed adhesive layer was attached to a stainless steel plate (SUS304) and pressed with a 2 kg roll. After 10 minutes of pressing, the adhesive strength was measured using a tensile tester in accordance with JIS Z0237 at a peel speed of 300 mm / min and a peel angle of 180°. The higher the adhesive strength, the better the adhesion to the skin. [Evaluation criteria] ○: 5N / 25mm or more, less than 20N / 25mm (good) ×: Less than 5N / 25mm (defective)

[0091] <Breathability> The moisture permeability was evaluated by conducting a test in accordance with JISL1099. 42 g of pure water at 40°C was placed in a cylindrical weighing container with a diameter of 70 mm, and the adhesive tape X2 was fixed as a lid to the weighing container with the adhesive coated side facing downwards, and the container was sealed. This was left to stand for 1 hour in a thermo-hygrostat chamber at 40°C and a relative humidity of 50%RH, and the amount of moisture permeated per square meter of area per 24 hours was calculated from the mass loss of the weighing container, and the moisture permeability (unit: g / m) of the adhesive tape X2 was determined. 2 24 hours). [Evaluation criteria] ◎: 2000g / m 2 24 hours or more (very good) ○:1500g / m 2 ·24h or more, 2000g / m 2 Less than 24 hours (good) △: 1000g / m 2 ·Over 24 hours, 1500g / m 2 Less than 24 hours (available) ×:1000g / m 2 Less than 24 hours (bad)

[0092] <Water resistance> The polyester separator was peeled off from the adhesive tape X2 cut to a size of 25 mm x 100 mm in an environment of 23°C and 50% RH, and the exposed adhesive layer was attached to a stainless steel plate (SUS304) and pressed with a 2 kg roll. After 10 minutes of pressing, the sample was immersed in purified water, and after 24 hours, the water resistance was evaluated according to the following criteria. [Evaluation criteria] ○: Fully adhered and no peeling observed (very good) △: Some peeling observed (good) ×: Completely peeled off (poor)

[0093] <Water resistance on the back side> Two pieces of adhesive tape X2, cut to 25mm x 60mm, were prepared as measurement samples. In an environment of 23°C and 50% RH, the polyester separator was peeled off from the sample. One piece was attached with the exposed adhesive layer to a stainless steel plate (SUS304), and the other piece was attached to the first, overlapping it by 25mm x 20mm, and then pressed with a 2kg roll. After 10 minutes of pressing, the tape was immersed in purified water. After 24 hours, the water resistance of the backside was evaluated according to the following criteria. [Evaluation criteria] ○: Fully adhered and no peeling observed (very good) △: Some peeling observed (good) ×: Completely peeled off (poor)

[0094] <Adhesive residue on skin> Adhesive tape X2 cut to 20 mm x 80 mm was applied to the adherend (the front upper arm of a volunteer) and then peeled off 24 hours later to evaluate the adhesive residue. [Evaluation criteria] ○: No adhesive remains at all (very good) △: Some adhesive residue is observed (good) ×: Glue remains on the entire surface (poor)

[0095] <Skin irritation resistance> The adhesive tape X2 cut to 20 mm x 80 mm was applied to the subject (the front upper arm of a volunteer), and after 24 hours, the adhesive tape X2 was peeled off to evaluate skin irritation. [Evaluation criteria] ○: No pain felt (good) △: Slight pain is felt, but no erythema is observed on the peeled surface (can be used) ×: Severe pain is felt and erythema is observed on the peeled surface (poor)

[0096] [Table 5]

[0097] [Table 6]

[0098] As can be seen from Tables 5 and 6, it was confirmed that by using the adhesive of the present invention, it is possible to obtain an adhesive tape for application to the skin that has high adhesion to the skin but has excellent adhesive strength so that the adhesive does not remain on the skin when removed, does not cause skin disorders such as rashes or stuffiness due to moisture, does not lose adhesive strength even after application, and has water resistance that prevents the tape from peeling off from the skin, and has excellent moisture permeability. It was also confirmed that even though the base material is polyurethane, moisture permeability is not impaired and the back surface has good water resistance.

Claims

1. Contains an acrylic copolymer (A) and a curing agent (C), The acrylic copolymer (A) is 10 to 80% by mass of an alkyl(meth)acrylate monomer (a-1) having an alkyl group with 4 to 8 carbon atoms, 15 to 50% by mass of an alkoxyalkyl(meth)acrylate monomer (a-2), 0.1 to 20% by mass of a vinyl-based monomer (a-3) having an amide group, 0.1 to 5% by mass of a vinyl-based monomer (a-4) having an acid group, and 0.01 to 1% by mass of a vinyl-based monomer (a-5) having a hydroxyl group. A copolymer of a monomer mixture comprising: A pressure-sensitive adhesive for application to skin, characterized in that the mass ratio [(a-4) / (a-5)] of a vinyl-based monomer (a-5) having a hydroxyl group to a vinyl-based monomer (a-4) having an acid group is 5 to 300.

2. 2. The adhesive for application to skin according to claim 1, wherein the curing agent (C) is at least one of an isocyanate compound and an epoxy compound.

3. 3. The adhesive for application to skin according to claim 1, wherein the content of the curing agent (C) is 0.01 to 5 parts by mass per 100 parts by mass of the acrylic copolymer (A).

4. The adhesive for application to skin according to claim 1, further comprising a tackifier (B).

5. An adhesive tape having an adhesive layer formed from the adhesive for application to skin according to any one of claims 1 to 4 on a substrate.

6. 6. The pressure-sensitive adhesive tape according to claim 5, wherein the substrate is at least one of a urethane sheet and a urethane nonwoven fabric.

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