On-demand adhesive double-sided tape

Abstract

The on-demand adhesive article includes a layer of adhesive and a backing layer in contact with the adhesive layer, the backing layer including a plurality of discontinuities, the discontinuities being gaps that are not visible to the naked eye when the adhesive article is in an unstressed state, and at least some of the discontinuities become gaps that allow adhesion of a first major surface of the adhesive layer to a substrate surface when the adhesive article is in a stressed state.

Description

SUMMARY OF THE INVENTION

[0001] Adhesive articles, medical constructs including these adhesive articles, and methods of preparing adhesive articles are disclosed herein.

[0002] In some embodiments, the adhesive article includes an adhesive layer having a first major surface and a second major surface, and a first backing layer having a first major surface and a second major surface, wherein the first major surface of the first backing layer is in contact with the second major surface of the adhesive layer. The first backing layer has a plurality of cuts, and the plurality of cuts are gaps, but the gaps are not visible to the naked eye when the adhesive article is in a state of not being subjected to stress, and when the adhesive article is in a state of being subjected to stress, at least some of the cuts become gaps that allow the second major surface of the adhesive layer to adhere to the substrate surface. In some embodiments, the adhesive article further includes a second backing layer in contact with the first major surface of the adhesive layer.

[0003] Adhesive constructs are also disclosed. In some embodiments, the adhesive construct includes a first substrate surface and an adhesive article attached to the first substrate surface. The adhesive article is as described above and includes an adhesive layer having a first major surface and a second major surface, and a first backing layer having a first major surface and a second major surface, wherein the first major surface of the first backing layer is in contact with the second major surface of the adhesive layer. The first backing layer has a plurality of cuts, and the cuts are gaps, but at least some of the gaps are not visible to the naked eye when the adhesive article is in a first state, and when the adhesive article is in a second state, at least some of the gaps that are not visible to the naked eye in the first state become gaps, and the second state is a state of higher stress of bending, stretching, or a combination thereof. The first major surface of the adhesive layer is in contact with the first substrate surface, and the gaps in the first backing layer allow the adhesive layer to adhere to the surface of the second substrate.

[0004] Methods for preparing adhesive articles are also disclosed. In some embodiments, the method includes preparing a first backing layer having a first main surface and a second main surface; modifying the first backing layer by making a plurality of cuts in the first backing layer without substantially removing material from the first backing layer such that the cuts are gaps when unstressed and the gaps are not visible to the naked eye, but when stressed, at least some of the gaps are visible to the naked eye; preparing an adhesive; and forming a layer of adhesive on the first main surface of the first backing layer such that the adhesive layer has a first main surface and a second main surface, and the second main surface of the adhesive layer is in contact with the first main surface of the first backing layer. [Brief explanation of the drawing]

[0005] This application can be better understood by considering the following detailed description of various embodiments of the present disclosure, together with the accompanying drawings.

[0006] [Figure 1] This is a cross-sectional view of the article disclosed herein. [Figure 2A] This is a top view of the article in this disclosure. [Figure 2B] This is a top view of another article in this disclosure. [Figure 3A] Figure 2A shows a top view of the extension-activated article. [Figure 3B] Figure 2B shows a top view of the extension-activated article. [Figure 4] This is a cross-sectional view of another article of this disclosure. [Figure 5A] This is a top view of another article in this disclosure. [Figure 5B] Figure 5A shows the extension-activated article. [Figure 5C] Figure 5B shows the stretched and deactivated article.

[0007] In the following description of the exemplary embodiments, reference is made to the accompanying drawings illustrating various embodiments that may be used to implement the Disclosure. It should be understood that the embodiments can be used without departing from the scope of the Disclosure, and that structural modifications may be made. These drawings are not necessarily to a constant scale. Similar numbers used in the drawings indicate similar components. However, it should be understood that the use of numbers to indicate components in a given drawing is not intended to limit components in other drawings that are indicated by the same number. [Modes for carrying out the invention]

[0008] Adhesives are used for a variety of marking, retention, protection, sealing, and shielding purposes. Adhesive tapes generally consist of a backing or substrate and an adhesive. Pressure-sensitive adhesives, a type of adhesive, are particularly preferred for many applications.

[0009] It is well known to those skilled in the art that pressure-sensitive adhesives have certain properties at room temperature, including (1) strong and persistent tackiness, (2) adhesion under pressure less than finger pressure, (3) sufficient ability to be retained on a substrate, and (4) sufficient cohesive force to be easily removed from the substrate. Materials known to function well as pressure-sensitive adhesives are polymers designed and formulated to exhibit the viscoelastic properties necessary to provide a desired balance of tackiness, peel strength, and shear strength. The polymers most commonly used in the preparation of pressure-sensitive adhesives are natural rubber, synthetic rubber (e.g., styrene / butadiene copolymer (SBR) and styrene / isoprene / styrene (SIS) block copolymer), various (meth)acrylate (e.g., acrylate and methacrylate) copolymers, and silicones. Each of these categories of materials has its own advantages and disadvantages.

[0010] In many applications, it is desirable to have double-sided tape. Double-sided tape, also called "transfer tape," is an adhesive tape that adheres to both exposed surfaces. Depending on the transfer tape, the exposed surfaces may simply be two surfaces with a single adhesive layer. Other transfer tapes are multilayer transfer tapes having at least two adhesive layers, which may be the same or different, and may include an intervening layer that does not necessarily have to be an adhesive layer.

[0011] One difficulty associated with double-sided tape is that, because the tape has two exposed adhesive layers, it can be difficult to transport, handle, and apply to a substrate. The use of a release liner covering one or both of the adhesive layers can make the transport, handling, and application of the tape to the substrate easier. However, the use of a release liner can be costly and inconvenient because it requires removing the release liner to expose the adhesive layers and then discarding the liner. This disclosure describes a tape having two adhesive surfaces, the second adhesive surface being in contact with a backing layer. The backing layer has a plurality of cuts, which are gaps, but are not visible to the naked eye when the adhesive article is not under stress. When under stress, at least some of the cuts become gaps that allow the first main surface of the adhesive layer to adhere to the substrate surface. Thus, the second adhesive surface is an on-demand adhesive surface, which is exposed when stress is applied to the adhesive article.

[0012] Tape articles in which both adhesive surfaces are in contact with a backing layer and both backing layers include multiple cuts as described above are also disclosed herein. In these articles, the adhesive article is non-adhesive until stress is applied to the adhesive article.

[0013] As used herein, the term “adhesive” refers to a polymer composition useful for bonding two adherends together. Examples of adhesives include pressure-sensitive adhesives and gel adhesives.

[0014] It is well known to those skilled in the art that pressure-sensitive adhesive compositions possess properties including (1) strong and persistent tackiness, (2) adhesion under pressure less than finger pressure, (3) sufficient ability to hold the adherend, and (4) sufficient cohesive force to be cleanly removed from the adherend. Materials known to function well as pressure-sensitive adhesives are polymers designed and formulated to exhibit the viscoelasticity necessary to provide the desired balance of tackiness, peel adhesion, and shear retention. Achieving the right balance of properties is not a simple process.

[0015] As used herein, the term “gel adhesive” refers to a viscous, semi-solid, crosslinked matrix containing a liquid or fluid that can adhere to one or more substrates. Gel adhesives may have some properties in common with pressure-sensitive adhesives, but are not pressure-sensitive adhesives. A “hydrogel adhesive” is a gel adhesive that contains water as the fluid within the crosslinked matrix.

[0016] As used herein, the term “cut” refers to a narrow opening created in a substrate by the penetration of a cutting tool such that the material is substantially not removed from the substrate by the cutting process. The terms “cut” and “slit” are used interchangeably.

[0017] The term "(meth)acrylate" refers to an alcohol monomer acrylic or methacrylate ester. Acrylates and methacrylate monomers or oligomers are collectively referred to as "(meth)acrylate" in this specification. A material called a "(meth)acrylate system" is a material that contains one or more (meth)acrylate materials and may optionally contain additional copolymerizable materials.

[0018] As used herein, the term "siloxane-based" refers to a polymer or polymer unit containing siloxane units. The terms silicone or siloxane are used interchangeably and refer to units having dialkyl or diarylsiloxane (-SiR2O-) repeating units.

[0019] The terms "room temperature" and "ambient temperature" are used interchangeably and mean a temperature in the range of 20°C to 25°C.

[0020] The terms "Tg" and "glass transition temperature" are used interchangeably. When measuring, the Tg value is determined by differential scanning calorimetry (DSC) at a scanning rate of 10°C / minute, unless otherwise indicated. Typically, the Tg value of the copolymer is not measured, but as understood by those skilled in the art, it is calculated using the well-known Fox equation with the homopolymer Tg value provided by the monomer supplier.

[0021] When referring to two layers, as used herein, the term "adjacent" means that the two layers are in close proximity to each other and there is no intervening open space between them. These may be in direct contact with each other (e.g., laminated together), or an intervening layer may be present.

[0022] As used herein, the term "pattern" refers to a plurality of cuts, the plurality of cuts form an array, the array takes on a pattern, and the pattern may be a "random pattern", which means that there is no easily distinguishable repeating unit within the array, or the array can be aligned along at least one axis. In some embodiments, the array is aligned along one axis, and in other embodiments, the array is aligned along two or more axes.

[0023] The terms "polymer" and "macromolecule" are used herein in accordance with their general usage in chemistry. Polymers and macromolecules are composed of many repeating subunits. As used herein, the term "macromolecule" is used to describe a group bonded to a monomer having a plurality of repeating units. The term "polymer" is used to describe the resulting material formed from a polymerization reaction.

[0024] The term "alkyl" means a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. Alkyl may be straight-chain, branched-chain, cyclic, or a combination thereof, and typically has from 1 to 20 carbon atoms. In some embodiments, the alkyl group contains from 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

[0025] The term "aryl" refers to a monovalent group that is aromatic and carbocyclic. Aryl may have from 1 to 5 rings that are connected or fused to an aromatic ring. Other ring structures may be aromatic, non-aromatic, or a combination thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.

[0026] The term "alkylene" refers to a divalent group that is a radical of an alkane. Alkylene may be straight-chain, branched-chain, cyclic, or a combination thereof. Alkylene often has from 1 to 20 carbon atoms. In some embodiments, alkylene contains from 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of alkylene may be on the same carbon atom (i.e., alkylidene) or on different carbon atoms.

[0027] The terms "free-radical polymerizable" and "ethylenically unsaturated" are used interchangeably and refer to reactive groups containing a carbon-carbon double bond that can be polymerized via a free-radical polymerization mechanism.

[0028] As used herein, the term “gap” refers to an air gap in a substrate that penetrates the entire thickness of the substrate. Gaps can be prepared by cutting, slitting, boring, etc. In this disclosure, gaps are described as being invisible to the naked eye when the substrate is not under stress (i.e., the underlying layer cannot be seen through the slit backing), and gaps are described as being visible to the naked eye and forming an “opening” when the substrate is under stress. As used herein, the term “opening” is used according to its typical definition and is a space through which light passes (meaning the underlying layer can be seen through the slit backing). As used herein, the term “hole” refers to an air gap on the surface of a substrate that is visible to the naked eye when it is both unstressed and under stress, and this is an opening in both unstressed and under stress.

[0029] Adhesive articles are disclosed herein. Generally, in some embodiments, the adhesive article includes a layer of adhesive having a first principal surface and a second principal surface, and a first backing layer having a first principal surface and a second principal surface. The first principal surface of the first backing layer is in contact with the second principal surface of the adhesive layer. The first backing layer has a plurality of gaps, which are not visible to the naked eye when the adhesive article is not under stress, and when under stress, at least some of the gaps become gaps that allow the second principal surface of the adhesive layer to adhere to the substrate surface. Thus, the second principal surface of the adhesive layer is an on-demand adhesive layer.

[0030] A wide range of adhesives are suitable for use in the adhesive layer of the adhesive articles of this disclosure. The adhesive layer may be a continuous layer, a discontinuous layer, or may consist of multiple layers or partial layers of adhesive. In some embodiments, the adhesive includes a pressure-sensitive adhesive, and in other embodiments, the adhesive includes a gel adhesive. Suitable pressure-sensitive adhesives include (meth)acrylate-based pressure-sensitive adhesives and siloxane-based pressure-sensitive adhesives.

[0031] One preferred class of (meth)acrylate-based pressure-sensitive adhesives includes copolymers derived from (A) at least one monoethylene unsaturated alkyl (meth)acrylate monomer (i.e., alkyl acrylate and alkyl methacrylate monomer) and (B) at least one monoethylene unsaturated free radical copolymerizable reinforcing monomer. The reinforcing monomer has a higher homopolymer glass transition temperature (Tg) than the alkyl (meth)acrylate monomer, thereby improving the glass transition temperature and cohesive strength of the resulting copolymer. In this specification, "copolymer" refers to polymers containing two or more different monomers, including terpolymers, tetrapolymers, etc.

[0032] Monomer A, which is a monoethylene unsaturated alkyl acrylate or methacrylate (i.e., (meth)acrylic acid ester), contributes to the flexibility and tackiness of the copolymer. Generally, monomer A has a homopolymer Tg of about 0°C or less. Typically, the alkyl group of the (meth)acrylate has an average of about 4 to about 20 carbon atoms, or an average of about 4 to about 14 carbon atoms. The alkyl group may optionally contain an oxygen atom in the chain, thereby forming, for example, an ether or alkoxy ether. Examples of monomer A include, but are not limited to, 2-methylbutyl acrylate, isooctyl acrylate, lauryl acrylate, 4-methyl-2-pentyl acrylate, isoamyl acrylate, sec-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, isodecyl acrylate, isodecyl methacrylate, and isononyl acrylate. Other examples include, but are not limited to, polyethoxylated or polypropoxylated methoxy(meth)acrylates such as CARBOWAX (commercially available from Union Carbide) and NK ester AM90G (commercially available from Shin Nakamura Chemical Industry). Suitable monoethylenically unsaturated (meth)acrylates that can be used as monomer A include isooctyl acrylate, 2-ethylhexyl acrylate, and n-butyl acrylate. Various combinations of monomers classified as monomer A can be used to produce copolymers.

[0033] Monomer B, a monoethylene unsaturated free radical copolymerizable reinforcing monomer, improves the glass transition temperature and cohesive strength of the copolymer. Generally, monomer B has a homopolymer Tg of at least about 10°C. Typically, monomer B is a reinforcing (meth)acrylic monomer containing acrylic acid, methacrylic acid, acrylamide, or (meth)acrylate. Examples of monomer B, but not limited to these, include acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-hydroxyethylacrylamide, diacetoneacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-ethyl-N-aminoethylacrylamide, N-ethyl-N-hydroxyethylacrylamide, N,N-dihydroxyethylacrylamide, t-butylacrylamide, N,N-dimethylaminoethylacrylamide, and N-octylacrylamide. Other examples of monomer B include itaconic acid, crotonic acid, maleic acid, fumaric acid, 2,2-(diethoxy)ethyl acrylate, 2-hydroxyethyl acrylate or methacrylate, 3-hydroxypropyl acrylate or methacrylate, methyl methacrylate, isobornyl acrylate, 2-(phenoxy)ethyl acrylate or methacrylate, biphenylyl acrylate, t-butylphenyl acrylate, cyclohexyl acrylate, dimethyladamantyl acrylate, 2-naphthyl acrylate, phenyl acrylate, N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, and N-vinylcaprolactam. Particularly suitable reinforcing acrylic monomers that can be used as monomer B include acrylic acid and acrylamide. Various combinations of reinforcing monoethylenically unsaturated monomers classified as monomer B can be used to produce copolymers.

[0034] Generally, (meth)acrylate copolymers are formulated to have a Tg of less than about 0°C, more typically less than about -10°C. Such (meth)acrylate copolymers generally contain about 60 to about 98 parts by percentage of at least one monomer A and about 2 to about 40 parts by percentage of at least one monomer B. In some embodiments, the (meth)acrylate copolymer has about 85 to about 98 parts by percentage of at least one monomer A and about 2 to about 15 parts by percentage of at least one monomer B.

[0035] Examples of suitable (meth)acrylate-based pressure-sensitive adhesives that can be applied to the skin are described in U.S. Reissue Patent No. 24,906. In some embodiments, a 97:3 isooctyl acrylate:acrylamide copolymer adhesive or a 70:15:15 isooctyl acrylate:ethylene oxide acrylate:acrylic acid terpolymer can be used, as described in U.S. Patent No. 4,737,410. Other useful adhesives are described in U.S. Patents No. 3,389,827, No. 4,112,213, No. 4,310,509, and No. 4,323,557.

[0036] Another suitable category of pressure-sensitive adhesives is siloxane-based adhesives. Examples of siloxane-based pressure-sensitive adhesives are those described in U.S. Patents No. 5,527,578 and 5,858,545, and International Application PCT / International Publication No. 00 / 02966. Specific examples include polydiorganosiloxane polyurea copolymers and their blends, as well as polysiloxane-polyalkylene block copolymers, as described in U.S. Patent No. 6,007,914. Other examples of siloxane pressure-sensitive adhesives include those formed from silanols, hydrogenated silicones, siloxanes, epoxides, and (meth)acrylates. When a siloxane pressure-sensitive adhesive is prepared from a (meth)acrylate-functionalized siloxane, the adhesive may be referred to as siloxane (meth)acrylate.

[0037] Siloxane-based adhesive compositions include at least one siloxane elastomer polymer and may also contain other components such as tackifying resins. Examples of elastomer polymers include urea-based siloxane copolymers, oxamide-based siloxane copolymers, amide-based siloxane copolymers, urethane-based siloxane copolymers, and mixtures thereof.

[0038] Useful siloxane polyurea block copolymers are disclosed, for example, in U.S. Patents 5,512,650, 5,214,119, 5,461,134, and 7,153,924, as well as in PCT / International Publications 96 / 35458, 98 / 17726, 96 / 34028, 96 / 34030, and 97 / 40103.

[0039] Another useful category of siloxane elastomers is oxamide-based polymers, such as polydiorganosiloxane polyoxamide block copolymers. An example of a polydiorganosiloxane polyoxamide block copolymer is presented, for example, in U.S. Patent Application Publication No. 2007-0148475.

[0040] Another useful class of siloxane elastomers is amide siloxane polymers. Such polymers are similar to urea polymers in that they contain amide bonds (-N(D)-C(O)-) instead of urea bonds (-N(D)-C(O)-N(D)-) (wherein C(O) represents a carbonyl group and D is hydrogen or an alkyl group).

[0041] Another useful class of siloxane elastomers is urethane-based siloxane polymers, such as siloxane polyurea-urethane block copolymers. Siloxane polyurea-urethane block copolymers contain reaction products of polydiorganosiloxanediamine (also called siloxanediamine), diisocyanate, and organic polyol. Structurally, such materials are very similar to the structure of formula I, except that the -N(D)-BN(D)- bond is replaced by an -OBO- bond. Examples of such polymers are presented, for example, in U.S. Patent No. 5,214,119.

[0042] In some embodiments, the siloxane-based pressure-sensitive adhesive further comprises a siloxane tackifier. While the siloxane tackifier was previously referred to as a "silicate" tackifier, this term has been replaced by the term "siloxane tackifier." The siloxane tackifier is added in an amount sufficient to achieve the desired tackiness and adhesion level. In some embodiments, multiple siloxane tackifiers can be used to achieve the desired performance.

[0043] Suitable siloxane tackifying resins are commercially available from suppliers such as Dow Corning (e.g., DC 2-7066), Momentive Performance Materials (e.g., SR545 and SR1000), and Wacker Chemie AG (e.g., BELSIL TMS-803).

[0044] Another category of adhesives used in medical applications is silicone gels. In this specification, the terms “siloxane” and “silicone” are used interchangeably. While the term “siloxane” generally supersedes “silicone,” both terms are used in the art. Silicone gels (crosslinked polydimethylsiloxane “PDMS”) materials have been used in dielectric fillers, vibration dampers, and medical therapies to promote scar tissue healing. Lightly crosslinked silicone gels are soft, viscous, elastic materials containing relatively high concentrations of fluid (liquid). Silicone gels are typically softer than silicone pressure-sensitive adhesives, resulting in less discomfort when adhered to the skin. The combination of reasonable adhesive retention on the skin and low skin trauma during removal makes silicone gels suitable for skin-friendly adhesive applications.

[0045] Silicone gel adhesives offer good adhesion to the skin with gentle removal and possess the ability to reposition. Examples of commercially available silicone gel adhesive systems include those marketed under trade names Dow Corning MG 7-9850, WACKER 2130, BLUESTAR 4317 and 4320, and NUSIL 6345 and 6350. These skin-friendly adhesives are formed by an addition-curing reaction between vinyl-terminated PDMS and hydrogen-terminated PDMS in the presence of a hydrosilylation catalyst (e.g., a platinum complex). The vinyl-terminated PDMS chains and hydrogen-terminated PDMS chains are called "functionalized" silicones due to their specific chemical moieties. Individually, such functionalized silicones are generally non-reactive, but together they form reactive silicone systems. Furthermore, the adhesive properties of the gel can be modified by incorporating silicone resins (sometimes called "silicate resins" or tackifiers) and PDMS with multiple hydrogen functional groups (crosslinking agents).

[0046] In some embodiments, the adhesive layer includes a multilayer adhesive. The multilayer adhesive includes at least two adhesive layers, the first adhesive layer including the first main surface of the adhesive layer of the adhesive article, and the second adhesive layer including the second main surface of the adhesive layer of the adhesive article. The first and second adhesive layers may be the same or different. Thus, the adhesive properties of the first main surface and the second main surface may be different.

[0047] The first backing layer is typically a thin film material. The film material has sufficient rigidity to provide support to the adhesive article. The substrate layer is modified by cutting and has sufficient flexibility to conform to an anatomical surface. Therefore, when applied to an anatomical surface, it can conform to and stretch and shrink the surface even if the surface moves. The modification process of this disclosure allows the use of a wide range of material films that would otherwise not conform to an anatomical surface. Among the categories of preferred materials are thermoplastics, elastomers, and nonwovens. The backing layer can be prepared from a wide range of materials, including polyolefins, polyurethanes, polyesters, polyether block amides, or natural fiber-based materials. One particularly preferred substrate is SONTARA nonwoven material from Sontara America, which is a tightly interlocking, non-perforated nonwoven film suitable for use in medical barrier and drape applications.

[0048] The substrate layer has a wide range of thicknesses. In some embodiments, the thickness is at least 10 micrometers and up to 254 micrometers (10 mils), and in some embodiments, the thickness is from 25 micrometers (1 mil) to a maximum of 178 micrometers (7 mils). A wide range of intermediate thicknesses is also preferred.

[0049] As described above, the substrate layer includes multiple cuts arranged in a pattern, and in some embodiments the pattern may be random, while in other embodiments the pattern is arranged along at least one axis. The two-dimensional surface of the substrate layer can be considered to have two main orthogonal axes, which are often referred to as the x-axis and the y-axis. From the method of making the film, the x-axis is often referred to as the "machine direction" or MD, and the orthogonal y-axis is referred to as the "cross direction" or CD. Typically, the multiple cuts are arranged in a pattern along the machine direction. This means that the lengths of the multiple cuts are aligned along the machine direction of the substrate layer.

[0050] Multiple cuts arranged in a pattern are gaps, but when the substrate layer is not under stress, these gaps are essentially invisible to the naked eye. When the adhesive article is under stress, at least some of the gaps become visible to the naked eye. As used herein, the term “under stress” includes stretching, bending, or a combination thereof. Since the cuts are very thin (i.e., essentially no width) when not under stress, they are typically described by their length and depth. Generally, since the cuts extend through the entire thickness of the substrate layer, the depth is identical to the thickness of the substrate layer. One parameter that can describe the relationship between the length and width of a cut is the aspect ratio. The term “aspect ratio” is typically used to describe particles, but as used herein, it is used to describe hole sizes or void areas where no material is present. In some embodiments, the aspect ratio (length to width) of a cut is greater than 1000. When stress is applied, the aspect ratio of the cut decreases. A preferred example of a cut is one centimeter in length and five micrometers in width.

[0051] In some embodiments, the multiple cuts may include at least some continuous cuts, meaning that the cuts extend from edge to edge of the surface. These cuts separate when stress is applied, forming edge-to-edge gaps within the backing and thus effectively bifurcating the backing layer.

[0052] The gaps can be more complex than the simple linear shapes described above. When unstressed, the gaps can have various two-dimensional shapes, such as crosses, stars, chevrons, letters, and numbers, provided they are not visible to the naked eye. When the adhesive article is under stress, at least a portion of the gap becomes a visible opening. Furthermore, when stress is applied to the article, the gaps not only become visible to the naked eye, but they also become openings through which light can pass. In this way, when stress is applied, the openings formed allow access to the adhesive layer through the substrate layer.

[0053] In some embodiments, the cuts are arranged in a specific pattern along the machine direction of the substrate. Often, the cuts are formed by a process known as “skip slitting,” in which a series of discontinuous slits are linearly formed within the substrate. If one were to follow the line of slits along the surface of the substrate, one would encounter a slit, where it ends, there would be an unslitted area, then a new slit, where it ends, there would be an unslitted area, and so on. This type of pattern is described in International Patent Application PCT / International Publication 19 / 043621. In these patterns, the area between the end of one slit and the beginning of the next slit is called the bridging area. While a broad pattern is preferred, in some embodiments, the pattern has a 50% offset. This means that if two linear arrangements are present in the machine direction, when observed in the width direction, the bridging area of ​​the first arrangement corresponds to the slits of the second arrangement, and vice versa. An additional example of a skip slit pattern is described in U.S. Patent Application 62 / 952789.

[0054] In some embodiments, multiple cuts are arranged in a pattern along two or more axes. This means that at least a portion of the cuts have lengths that are not aligned with the mechanical direction of the substrate layer but are offset from alignment by an angle of up to 90°. The lengths offset from alignment by 90° with the mechanical direction of the substrate layer are aligned in the width direction.

[0055] Multiple cuts can be created in several different ways, as long as the method does not involve removing a substantial amount of material from the substrate layer, and the cuts form gaps that are essentially invisible to the naked eye when unstressed, and at least some of the gaps become visible to the naked eye when the adhesive article is stressed. Among these methods, in particular, cuts are introduced into the substrate layer when the layer is formed, for example by extrusion, molding, and machining. Other methods introduce cuts into the substrate layer after it has been formed, by cutting with a cutting tool such as a knife, linear blade, rotary die blade, water jet, or laser light, or by stamping with a stamping tool. In some embodiments, cuts are created by feeding the substrate layer to a nip including a rotary die blade and anvil so that a die cuts across the entire substrate layer to form a cut pattern.

[0056] Conceptually, a slit is a cut that penetrates material of minimal thickness. Thus, a slit differs from a perforation, which is a permanent gap in the backing layer. In practice, forming techniques may involve the removal of material or the creation of a gap between the edges of the slit. Most cutting techniques produce a “groove,” or some physical width, for the cut. For example, a laser cutter can remove some material to create a slit, a router can cut material to create a slit, and crush cutting can produce some deformation at the edges of the material, forming a physical gap. Forming techniques require material between the opposing surfaces of the slit, creating a gap or groove in the slit. In most cases, the gap or groove of a slit is less than the thickness of the material. For example, a slit pattern cut into paper 0.007 inches (178 micrometers) thick may have slits with gaps of approximately 0.007 inches (178 micrometers) or less. However, it is understood that the physical gap of a slit can be increased to several times the thickness of the substrate. As described above, the slits are formed in the backing layer in a manner that minimizes material removal. In this way, the slits are not visible when the article is not under stress and therefore do not form permanent openings in the backing.

[0057] In some embodiments, adhesive articles can be activated as needed to enable adhesion, as well as deactivated as needed to help reduce the adhesive strength. In these embodiments, articles containing slits are subjected to stress in one direction to activate the article and enable adhesion, and when the article is removed, the article is subjected to stress in a perpendicular direction to deactivate it. Deactivation can cause shrinkage of the gaps in the backing layer, and also cause wrinkles or buckling of the backing layer, which can help delaminate the adhesive article.

[0058] In some embodiments, the adhesive article further includes a second backing layer having a first main surface and a second main surface, the second main surface of the second backing layer in contact with the first main surface of the adhesive layer. The second backing layer has a plurality of cuts, which are gaps, but are not visible to the naked eye when the adhesive article is not under stress, and when under stress, at least some of the cuts become gaps that allow the adhesive layer to adhere to the substrate surface. A preferred example of the second backing layer is described above and includes the backing layer described as the first backing layer. The second backing layer may be identical to or different from the first backing layer.

[0059] The advantage of including a second backing layer in a double-sided adhesive article is that it is non-adhesive when both outer surfaces are unstressed, allowing for easy transport and handling. In many adhesive articles, a release liner is used to protect the adhesive surface until the article is used. In these articles, the release liner needs to be removed when the article is used. This is inconvenient and may require the removal of the release liner for disposal or reuse. In the articles of this disclosure including two backing layers, the article is non-adhesive when unstressed, and becomes an adhesive article when stress is applied. As described above, stress includes stretching, bending, or a combination thereof. In this way, the article can be seen as an on-demand adhesive article.

[0060] Adhesive structures are also disclosed. In some embodiments, the adhesive structure includes a first substrate surface and an adhesive article attached to the first substrate surface. The adhesive article includes the adhesive article described above. In some embodiments, the adhesive article includes a layer of adhesive having a first main surface and a second main surface, and a first backing layer having a first main surface and a second main surface, wherein the first main surface of the first backing layer is in contact with the second main surface of the adhesive layer. The first backing layer has a plurality of gaps, which are voids, but at least some of the voids are not visible to the naked eye when the adhesive article is in a first state, and at least some of the voids that are not visible to the naked eye in the first state become voids when the adhesive article is in a second state. The second state is a state of higher stress, such as bending, stretching, or a combination thereof. The first main surface of the adhesive layer is in contact with the first substrate surface, and the voids in the first backing layer allow the second main surface of the adhesive layer to adhere to the surface of the second substrate. In some embodiments, the adhesive article is a medical article, and the first substrate surface is mammalian skin.

[0061] The adhesive articles are described in detail above and may include single-layer or multi-layer adhesives, and may further include a second backing layer. Suitable adhesives and backing layers are described above.

[0062] When the adhesive article is under stress and the slits in the first backing layer are gaps, a broad second substrate can be bonded to the second surface of the adhesive layer. In some embodiments, the second substrate includes an article. A suitable example of an article is a device. A wide range of devices are suitable, including, for example, wearable medical devices, sensors, catheters, suction ports, insulin pump controllers, monitors, and the like.

[0063] Methods for preparing adhesive articles are also disclosed herein. In some embodiments, the method includes preparing a first backing layer having a first main surface and a second main surface; modifying the first backing layer by making a plurality of cuts in a substrate layer without substantially removing material from the first backing layer such that the cuts are gaps that are not visible to the naked eye when unstressed, and at least some of the gaps are visible to the naked eye when stressed; preparing an adhesive; and forming a layer of adhesive on the first main surface of the substrate layer. The adhesive layer has a first main surface and a second main surface, the second main surface of the adhesive layer is in contact with the first main surface of the first backing layer.

[0064] A wide variety of techniques are suitable for modifying the first backing layer, provided that no material is removed from the first backing layer. In some embodiments, modifying the first backing layer involves making multiple cuts in the first backing layer with a knife, blade, water jet, or laser. A wide variety of techniques are suitable for modifying the first backing layer. Examples of modification include cutting with a cutting tool such as a knife, linear blade, rotary die blade, water jet, or laser, or by stamping with a stamping tool. In some embodiments, the cuts are made by feeding the first backing layer to a nip including a rotary die blade and anvil so that the die cuts across the entire first backing layer to form a cut pattern.

[0065] In many embodiments, the first backing layer is modified before forming the adhesive layer on the first main surface of the substrate layer. In this embodiment, the first backing layer may be modified at a different location or time than the formation of the adhesive article. In some embodiments, the adhesive layer on the first main surface of the substrate layer is formed before modifying the substrate layer. In this embodiment, a pre-fabricated tape article can be modified to become an on-demand double-sided adhesive article.

[0066] As described above, the adhesive layer may be continuous or discontinuous, and may be a multilayer adhesive. Suitable adhesives are described above.

[0067] In some embodiments, the method further includes preparing a second backing layer having a first main surface and a second main surface, and bringing the second main surface of the second backing layer into contact with the first main surface of the adhesive layer. The second backing layer, like the first backing layer, has a plurality of cuts, which are gaps, but are not visible to the naked eye, and at least some of the gaps become visible to the naked eye when under stress.

[0068] The articles of this disclosure can be further understood by referring to the figures.

[0069] Figure 1 shows a cross-sectional view of an article 100 having a backing layer 110 and an adhesive layer 120. Suitable backing layers and adhesive layers are described above. The backing layer 110 is modified with slits as described above.

[0070] Figures 2A and 2B show top views of embodiments of the article shown in Figure 1. In the embodiment shown in Figure 2A, the article 200 has a backing layer 210 having an array of slits 230. In the embodiment shown in Figure 2B, the backing layer 210 has an array of slits 230 and a continuous slit 231.

[0071] Figures 3A and 3B show top views of article 300, which is article 200 shown in Figures 2A and 2B, after being activated by stretching. In Figure 3A, the activated slit 330' forms a gap that allows the adhesive layer 320 to be exposed. In Figure 3B, similarly to Figure 3A, the activated slit 330' forms a gap that allows the adhesive layer 320 to be exposed. Furthermore, the activated slit 331' forms a gap that allows the underlying adhesive layer to be exposed. In Figure 3B, the gap 331' is a separation point in the backing layer.

[0072] Figure 4 shows a cross-sectional view of article 400 including a first backing layer 410, an adhesive layer 420, and a second backing layer 440. Preferred first and second backing layers and preferred adhesive layers are described above.

[0073] Figures 5A to 5C illustrate schemes for activating and deactivating the articles of this disclosure. Figure 5A shows the deactivating article described above. In Figure 5B, the article is stretched in the direction of one or more arrows. As shown, the stretching causes the slits to form gaps. In Figure 5C, the article of Figure 5B is deactivated by stretching in the orthogonal direction indicated by the arrows. As shown, deactivation can reduce the adhesion of the article by causing a reduction in gaps in the backing layer and also causing wrinkles in the backing layer. [Examples]

[0074] These examples are for illustrative purposes only and are not intended to limit the scope of the attached claims. The following abbreviations are used: cm = centimeter.

[0075] Example 1 A strip of tape (3M Vinyl Tape 471, 3M Company, St. Paul, MN), approximately 6 cm wide and 12 cm long, was slit longitudinally using a skip slit pattern. The slits were approximately 4 cm long and spaced approximately 1 cm apart. The rows of slits were also spaced approximately 1 cm apart. After slitting, the tape was adhered to a vertical surface with the slits oriented horizontally. When a test specimen (3M EASY TRAP Sweep&Dust Sheet, 3M Company, St. Paul, MN) was pressed against the backing of the slit tape, it was found that it did not adhere.

[0076] Next, the tape was removed from the surface, stretched to increase its width by approximately 2 cm, and a slit was opened. As before, the tape was reattached to the vertical surface. Visual inspection of the tape showed that the adhesive was exposed through the backing toward the end of the slit. When the test specimen was pressed again against the backing of the slitted and stretched tape, it was found to be adhered. Examples of embodiments of the present invention are listed in the following sections [Aspect 1] to [Aspect 21]. [Aspect 1] A layer of adhesive having a first main surface and a second main surface, A first backing layer having a first main surface and a second main surface, wherein the first main surface of the first backing layer is in contact with the second main surface of the adhesive layer, the first backing layer has a plurality of cuts, the plurality of cuts being gaps, but when the adhesive article is not under stress, the gaps are not visible to the naked eye, and when under stress, at least some of the cuts become gaps that enable adhesion of the second main surface of the adhesive layer to the substrate surface, Adhesive articles, including those containing adhesives. [Aspect 2] The adhesive article according to embodiment 1, wherein the plurality of cuts are arranged in a specific pattern along one axis or along two or more axes. [Aspect 3] The adhesive article according to embodiment 1, wherein at least some of the plurality of cuts are continuous cuts. [Aspect 4] The adhesive article according to embodiment 1, wherein the adhesive includes a gel adhesive or a pressure-sensitive adhesive. [Aspect 5] The adhesive article according to Embodiment 1, wherein the adhesive layer comprises a multilayer adhesive, the multilayer adhesive comprises at least two adhesive layers, the first adhesive layer comprises the first main surface of the adhesive layer, the second adhesive layer comprises the second main surface of the adhesive layer, and the first and second adhesive layers are the same or different. [Aspect 6] The adhesive article according to embodiment 1, wherein the first backing layer comprises a thermoplastic film of polyolefin, polyurethane, polyester, or polyether block amide. [Aspect 7] The adhesive article according to embodiment 1, wherein the state of being subjected to the aforementioned stress includes elongation, bending, or a combination thereof. [Aspect 8] The adhesive article according to Embodiment 1, further comprising a second backing layer having a first main surface and a second main surface, wherein the second main surface of the second backing layer is in contact with the first main surface of the adhesive layer, the second backing layer has a plurality of cuts, the plurality of cuts being gaps, but the gaps are not visible to the naked eye when the adhesive article is not under stress, and when under stress, at least some of the cuts become gaps that allow the adhesive layer to adhere to the substrate surface. [Aspect 9] The adhesive article according to embodiment 8, wherein the first backing layer and the second backing layer contain the same material. [Aspect 10] The first substrate surface and An adhesive structure comprising an adhesive article attached to the surface of the first substrate, The adhesive article is It includes an adhesive layer having a first main surface and a second main surface, and a first backing layer having the first main surface and the second main surface, The first main surface of the first backing layer is in contact with the second main surface of the adhesive layer, and the first backing layer has a plurality of cuts, the cuts being gaps, but when the adhesive article is in a first state, at least some of the gaps are not visible to the naked eye, and when the adhesive article is in a second state, at least some of the gaps that are not visible to the naked eye in the first state become gaps, the second state being a state of higher stress, such as bending, stretching, or a combination thereof. The first main surface of the adhesive layer is in contact with the first substrate surface. The gap in the first backing layer is an adhesive structure that enables the second main surface of the adhesive layer to adhere to the surface of the second substrate. [Aspect 11] The adhesive structure according to embodiment 10, wherein the first substrate includes mammalian skin. [Aspect 12] The adhesive structure according to embodiment 10, wherein the plurality of cuts are arranged in a specific pattern along one axis or along two or more axes. [Aspect 13] The adhesive structure according to embodiment 10, wherein the adhesive includes a gel adhesive or a pressure-sensitive adhesive. [Aspect 14] The adhesive structure according to embodiment 10, wherein the backing layer comprises a thermoplastic film of polyolefin, polyurethane, polyester, or polyether block amide. [Aspect 15] The adhesive structure according to embodiment 10, wherein the second substrate includes an article. [Aspect 16] The adhesive structure according to embodiment 15, wherein the article includes a device. [Aspect 17] The adhesive structure according to embodiment 16, wherein the device includes a wearable medical device, a sensor, a catheter, a suction port, a controller for an insulin pump, or a monitor. [Aspect 18] A method for preparing adhesive articles, To prepare a first backing layer having a first main surface and a second main surface, The first backing layer is modified by making multiple cuts in the first backing layer without substantially removing material from the first backing layer, such that when not under stress, the cuts are gaps and are not visible to the naked eye, but when under stress, at least some of the gaps become visible to the naked eye. Prepare the adhesive, A method comprising forming an adhesive layer on the first main surface of the first backing layer such that the adhesive layer has a first main surface and a second main surface, and the second main surface of the adhesive layer is in contact with the first main surface of the first backing layer. [Aspect 19] The method according to embodiment 18, wherein modifying the substrate layer by making a plurality of cuts in the substrate layer includes cutting with a knife, blade, water jet, or laser light. [Aspect 20] The method according to embodiment 18, wherein the adhesive layer on the first main surface of the first backing layer is formed before the first backing layer is modified. [Aspect 21] The present invention provides a second backing layer having a first main surface and a second main surface, wherein the second backing layer has a plurality of cuts, the cuts being gaps, the gaps being invisible to the naked eye, but when under stress, at least some of the gaps becoming visible to the naked eye. The second main surface of the second backing layer is brought into contact with the first main surface of the adhesive layer, The method according to embodiment 18, further comprising:

Claims

1. A layer of adhesive having a first main surface and a second main surface, wherein the adhesive includes a gel adhesive or a pressure-sensitive adhesive. A first backing layer having a first main surface and a second main surface, wherein the first main surface of the first backing layer is in contact with the second main surface of the adhesive layer, the first backing layer has a plurality of slits, and the bonded article is configured to transition between a stress-free state and a stressed state, and when the bonded article transitions from a stress-free state to a stressed state, at least some of the slits become gaps that allow the second main surface of the adhesive layer to adhere to the substrate surface, including, and, The aforementioned multiple cuts are, A row of first cuts, including a first cut and a second cut offset from the first cut and defining the gap between them, An adhesive article comprising a second row of cuts, which includes a third cut offset from a first row of cuts and aligned with the gap.

2. The adhesive article according to claim 1, wherein the plurality of cuts are arranged in a specific pattern along one axis or along two or more axes.

3. The adhesive article according to claim 1, wherein at least some of the plurality of cuts are continuous cuts.

4. The adhesive article according to claim 1, wherein the adhesive layer comprises a multilayer adhesive, the multilayer adhesive comprises at least two adhesive layers, the first adhesive layer comprises the first main surface of the adhesive layer, the second adhesive layer comprises the second main surface of the adhesive layer, and the first and second adhesive layers are the same or different.

5. The adhesive article according to claim 1, wherein the first backing layer comprises a thermoplastic film of polyolefin, polyurethane, polyester, or polyether block amide.

6. The adhesive article according to claim 1, wherein the state of being subjected to the aforementioned stress includes elongation, bending, or a combination thereof.

7. The adhesive article according to claim 1, further comprising a second backing layer having a first main surface and a second main surface, wherein the second main surface of the second backing layer is in contact with the first main surface of the adhesive layer, the second backing layer has a plurality of cuts, and when the adhesive article transitions from a stress-free state to a stressed state, at least some of the cuts become gaps that allow the adhesive layer to adhere to the substrate surface.

8. The adhesive article according to claim 7, wherein the first backing layer and the second backing layer comprise the same material.

9. The first substrate surface and An adhesive structure comprising the adhesive article according to claim 1 attached to the surface of the first substrate.

10. A method for preparing adhesive articles, To prepare a first backing layer having a first main surface and a second main surface, The first backing layer is modified by making a plurality of cuts in the first backing layer without substantially removing material from the first backing layer, thereby configuring the bonded article to transition between a stress-free state and a stressed state. Prepare an adhesive, wherein the adhesive includes a gel adhesive or a pressure-sensitive adhesive. A layer of adhesive is formed on the first main surface of the first backing layer, such that the adhesive layer has a first main surface and a second main surface, and the second main surface of the adhesive layer is in contact with the first main surface of the first backing layer. Includes, When the adhesive article transitions from a state without stress to a state with stress, at least some of the cuts become gaps that allow the second main surface of the adhesive layer to adhere to the substrate surface, and The aforementioned multiple cuts are, A row of first cuts, including a first cut and a second cut offset from the first cut and defining the gap between them, A method comprising a second row of cuts, which includes a third cut offset from a first row of cuts and aligned with the gap.

11. The method according to claim 10, wherein modifying the substrate layer by making a plurality of cuts in the substrate layer includes cutting with a knife, blade, water jet, or laser light.

12. The method according to claim 10, wherein the adhesive layer on the first main surface of the first backing layer is formed before the first backing layer is modified.

13. The present invention provides a second backing layer having a first main surface and a second main surface, wherein the second backing layer has a plurality of cuts. The second main surface of the second backing layer is brought into contact with the first main surface of the adhesive layer, The method according to claim 10, further comprising:

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