Adhesive tape and method for producing adhesive tape

Abstract

An object of the present invention is to provide an adhesive tape that is less likely to be peeled off over a long period of time.SOLUTION: An aspect of the present invention is a pressure-sensitive adhesive tape including: a substrate layer containing a polyvinyl chloride resin; and a rubber-based pressure-sensitive adhesive layer provided on at least one surface of the substrate layer. The rubber-based pressure-sensitive adhesive layer contains a (meth) acrylic polymer. The pressure-sensitive adhesive tape has an adhesive strength JISZ0237 of 1.8 to 4. V1 / 0N as measured at 23 °C by a method in conformity with 10mm: 2000. The pressure-sensitive adhesive tape has an adhesive strength retention rate of 90% or more, the adhesive strength retention rate being calculated based on adhesive strengths V2 and V1 measured after the pressure-sensitive adhesive tape is stored in an atmosphere at 60 °C for 10 days.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive tape and a method for producing an adhesive tape. [Background technology]

[0002] Adhesive tapes are used to bundle multiple electric wires in electrical work, automotive components, indoor and outdoor exterior components, repair components, etc. High adhesive strength is required for adhesive tapes used to bundle such electric wires.

[0003] A known method for improving the adhesive strength of adhesive tapes is to use an adhesive composition in which a tackifier resin is blended with an adhesive. Such adhesive compositions generate large amounts of volatile organic compounds (VOCs) because the adhesive and the tackifier resin are made compatible in an organic solvent. This poses a problem of significant environmental impact.

[0004] Meanwhile, adhesive tapes for electric wires, which are placed in environments prone to high temperatures, are required to have high heat resistance in addition to the adhesive strength described above. When an adhesive tape with low heat resistance is used, the problem of peeling occurs at the ends of the adhesive tape wrapped around the electric wire. To improve the heat resistance of adhesive tapes, a method using a crosslinked adhesive composition (for example, Patent Document 1) is known. However, such crosslinking treatment is generally carried out in an organic solvent such as toluene, which still poses a problem of environmental load due to VOCs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-256242 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above-mentioned circumstances, the present inventors have investigated an adhesive tape that has a low environmental impact during production and high adhesive strength. In the course of their investigation, they have found that when an adhesive tape obtained by a production method using, for example, an aqueous latex is used for the above-mentioned applications, the adhesive strength of the adhesive tape decreases after several years of use, and peeling occurs in some cases.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide an adhesive tape that is resistant to peeling over a long period of time. [Means for solving the problem]

[0008] As a result of extensive research, the inventors have found that the above problems can be solved by using a specific component as an adhesive and ensuring that the adhesive strength satisfies specific parameters, and have thus completed the present invention.

[0009] According to the present invention, the following is provided: [1] A pressure-sensitive adhesive tape comprising a substrate layer containing a polyvinyl chloride resin and a rubber-based pressure-sensitive adhesive layer provided on at least one surface of the substrate layer, the rubber-based pressure-sensitive adhesive layer contains a (meth)acrylic polymer, The adhesive tape has an adhesive strength V1 of 1.8 to 4.0 N / 10 mm measured at 23°C by a method in accordance with JIS Z0237:2000, The adhesive strength retention rate calculated from the following formula (1) based on the adhesive strengths V2 and V1 measured after storing the adhesive tape in an atmosphere at 60°C for 10 days is 90% or more. Adhesive force maintenance rate (%)=V2 / V1×100 (1) Adhesive tape. [2] The pressure-sensitive adhesive tape according to [1], wherein the content of the natural rubber component in the rubber-based pressure-sensitive adhesive layer is 2 to 15% by mass. [3] The pressure-sensitive adhesive tape according to [1] or [2], wherein the (meth)acrylic polymer has a glass transition temperature of 80 to 110°C. [4] The pressure-sensitive adhesive tape according to any one of [1] to [3], wherein the content of structural units derived from alkyl (meth)acrylate in the total of 100% by mass of monomer units constituting the (meth)acrylic polymer is 60% by mass or more. [5] The rubber-based pressure-sensitive adhesive layer further contains modified natural rubber, The pressure-sensitive adhesive tape according to any one of [1] to [4], wherein the modified natural rubber is a graft copolymer of natural rubber and alkyl (meth)acrylate. [6] The pressure-sensitive adhesive tape according to any one of [1] to [5], wherein the content of the (meth)acrylic polymer in the rubber-based pressure-sensitive adhesive layer is 5 to 25% by mass. [7] The rubber-based pressure-sensitive adhesive layer further contains a tackifier, The pressure-sensitive adhesive tape according to any one of [1] to [6], wherein the content of the tackifier in the rubber-based pressure-sensitive adhesive layer is 40 to 60 mass %. [8] The pressure-sensitive adhesive tape according to any one of [1] to [7], wherein the rubber-based pressure-sensitive adhesive layer has a storage modulus at 23°C of 0.25 to 0.45 MPa. [9] The pressure-sensitive adhesive tape according to any one of [1] to [8], wherein the rubber-based pressure-sensitive adhesive layer has a thickness of 10 to 40 μm.

[10] The pressure-sensitive adhesive tape according to any one of [1] to [9], which is used for bundling electric wires.

[11] A method for producing the pressure-sensitive adhesive tape according to any one of [1] to

[10] , a pressure-sensitive adhesive layer forming step of forming the rubber-based pressure-sensitive adhesive layer on at least one surface of the base material layer, The method for producing a pressure-sensitive adhesive tape, wherein the pressure-sensitive adhesive layer forming step comprises applying an aqueous latex containing a rubber-based pressure-sensitive adhesive composition to at least one surface of the substrate layer. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape that is resistant to peeling over a long period of time. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the present invention will be described in detail. The present invention is not limited to these descriptions. Each feature of the embodiments shown below can be combined with each other. Also, an invention can be formed independently for each feature. Furthermore, among the following embodiments, elements not defined in the claims are arbitrary elements and can be omitted.

[0012] <Explanation of Terms> In this specification, for example, the description "A to B" means A or more and B or less. In this specification, for example, the description "within the range between any two of the exemplified numerical values" means that when the exemplified numerical values are A and B (A < B), it is A or more or more than A, and B or less or less than B.

[0013] 1 Adhesive Tape The adhesive tape according to this embodiment includes a base material layer and an adhesive layer. The adhesive layer according to this embodiment is provided on at least one surface of the base material layer. Typically, it is preferable that the adhesive layer according to this embodiment is provided on one surface (single-sided) of the base material layer. Also, the adhesive tape according to this embodiment may have the adhesive layer provided directly on at least one surface of the base material layer, or the adhesive layer may be provided via other layers (for example, the undercoat layer described later).

[0014] 1.1 Base Material Layer The base material layer according to this embodiment preferably contains a polyvinyl chloride resin and is formed from a resin composition containing the polyvinyl chloride resin.

[0015] 1.1.1 Polyvinyl Chloride Resin The polyvinyl chloride resin according to the present embodiment preferably has an average degree of polymerization of 500 to 2000, more preferably 1000 to 2000, and even more preferably 1000 to 1500. The average degree of polymerization of the polyvinyl chloride resin may be, for example, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000, or may be within a range between any two of the values ​​exemplified herein. Two or more polyvinyl chloride resins with different average degrees of polymerization may also be used. When the lower limit of the average degree of polymerization of the polyvinyl chloride resin is within this range, the polymer chains become entangled, and when a resin composition is prepared, the content of the plasticizer described below falls within a suitable range, thereby improving the tensile elongation of the pressure-sensitive adhesive tape. When the upper limit of the average degree of polymerization of the polyvinyl chloride resin is within this range, gelation is facilitated and film-forming properties are excellent.

[0016] In the base layer according to this embodiment, when the resin composition is taken as 100% by mass, the content of the polyvinyl chloride resin is preferably 40% by mass or more, and more preferably 50% by mass or more.

[0017] 1.1.2 Plasticizers The resin composition according to this embodiment preferably further contains a plasticizer. The plasticizer according to this embodiment is not particularly limited as long as it can impart flexibility to the base layer. Examples of the plasticizer according to this embodiment include carboxylic acid ester plasticizers, polyester plasticizers, epoxy plasticizers, and phosphoric acid plasticizers. These plasticizers may be used alone or in combination of two or more. Preferred plasticizers according to this embodiment are carboxylic acid ester plasticizers and polyester plasticizers. Furthermore, from the viewpoint of cost, preferred plasticizers according to this embodiment are carboxylic acid ester plasticizers.

[0018] 1.1.2.1 Carboxylic acid ester plasticizers Examples of the carboxylic acid ester-based plasticizer according to this embodiment include phthalate esters, isophthalate esters, trimellitate esters, adipate esters, and terephthalate esters. Phthalate esters and trimellitate esters are preferred as the plasticizer according to this embodiment. When such a type of plasticizer is used, the melt viscosity of the resin composition is likely to decrease, so that the thickness is likely to be uniform during film formation, and pinholes are unlikely to occur in the base layer. Furthermore, from the viewpoint of cost, phthalate esters are preferred as the plasticizer according to this embodiment.

[0019] Examples of phthalate esters according to this embodiment include diisononyl phthalate (DINP), diheptyl phthalate (DHP), di-2-ethylhexyl phthalate (DOP), di-n-octyl phthalate (n-DOP), and diisodecyl phthalate (DIDP). Preferred plasticizers according to this embodiment are diesters of phthalic acid with alcohols having 9 to 10 carbon atoms, such as diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP). Such plasticizers have an excellent plasticizing effect on polyvinyl chloride resins, reducing bleed-out.

[0020] An example of the trimellitic ester according to the present embodiment is trioctyl trimellitate (TOTM). When the plasticizer is of this type, the resin composition has excellent heat resistance.

[0021] Examples of the adipic acid ester according to the present embodiment include diisononyl adipate (DINA) and dioctyl adipate (DOA). When the plasticizer is of such a type, the resin composition has excellent flexibility and film-forming properties.

[0022] 1.1.2.2 Polyester plasticizers Examples of polyester-based plasticizers according to this embodiment include polyesters of dibasic acids and glycols. Examples of dibasic acids include phthalic acid, adipic acid, and sebacic acid. Examples of glycols include 1,2-propanediol and butanediol. These types of plasticizers have a relatively large molecular weight, which reduces the volatility of the resin composition, and a relatively high polarity, which results in excellent oil resistance.

[0023] In the substrate layer according to the present embodiment, when the resin composition is taken as 100% by mass, the plasticizer content is preferably 15 to 50% by mass, and more preferably 20 to 45% by mass. The plasticizer content in the resin composition may be, for example, 15, 20, 25, 30, 35, 40, 45, or 50% by mass, or may be within a range between any two of the values ​​exemplified here. When the plasticizer content is equal to or greater than the lower limit, the resin composition attains an appropriate hardness during kneading, improving the film-forming properties of the substrate. When the plasticizer content is equal to or less than the upper limit, the strength of the pressure-sensitive adhesive tape is improved.

[0024] 1.1.3 Fillers The substrate layer according to this embodiment may further contain a filler. The filler according to this embodiment is not particularly limited as long as it can increase the weight of the substrate layer and improve its hardness. An inorganic filler is preferred as the filler according to this embodiment. Using such a filler can easily achieve both the reinforcing effect and flexibility of the substrate layer. Examples of fillers according to this embodiment include calcium carbonate, aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide, potassium hydroxide, barium hydroxide, triphenyl phosphite, ammonium polyphosphate, polyphosphate amide, zirconium oxide, magnesium oxide, zinc oxide, titanium oxide, molybdenum oxide, guanidine phosphate, hydrotalcite, smectite, zinc borate, zinc borate anhydrous, zinc metaborate, barium metaborate, antimony oxide, antimony pentoxide, red phosphorus, mica, talc, alumina, silica, boehmite, bentonite, sodium silicate, calcium silicate, calcium sulfate, and magnesium carbonate. These fillers may be used alone or in combination of two or more.

[0025] 1.1.4 Other additives The substrate layer according to the present embodiment may contain other additives as needed, as long as the effects of the present invention are not impaired. Examples of other additives include colorants (including pigments such as carbon black), stabilizers, lubricants, elastomers, antioxidants, and ultraviolet absorbers.

[0026] 1.1.4.1 Stabilizers Examples of the stabilizer according to this embodiment include metal soaps (metal-based composite stabilizers). The inclusion of a stabilizer such as metal soaps facilitates improved thermal stability of the base layer. Examples of the metal-based composite stabilizer include fatty acid calcium, fatty acid zinc, and fatty acid barium. Examples of the fatty acid component of the metal-based composite stabilizer include lauric acid, stearic acid, and ricinoleic acid. Specific examples of such metal-based composite stabilizers include calcium laurate, calcium stearate, calcium laurate, calcium stearate, calcium ricinoleate, zinc laurate, zinc ricinoleate, zinc stearate, barium laurate, barium stearate, and barium ricinoleate. These may be used alone or in combination. Note that, from the viewpoint that the thermal stability effect is further enhanced by combining them, a Ca-Zn-based metal stabilizer containing fatty acid calcium and fatty acid zinc is preferably used. The content of the metal-based composite stabilizer according to this embodiment is preferably 0.1 to 10% by mass, and more preferably 1 to 5% by mass, based on 100% by mass of the resin composition.

[0027] 1.1.4.2 Lubricants Examples of lubricants according to the present embodiment include higher fatty acids such as stearic acid and palmitic acid; higher alcohols such as palmityl alcohol and stearyl alcohol; metal salts of higher fatty acids such as calcium stearate, zinc stearate, barium stearate, aluminum stearate, magnesium stearate, and sodium palmitate; higher fatty acid esters such as butyl stearate and glyceryl monostearate; and higher fatty acid amides such as oleic acid amide, stearic acid amide, and erucic acid amide. Here, "higher" refers to a carbon number of 9 or more, preferably 9 to 30. These may be used alone or in combination. Among these, stearic acid is preferred from the viewpoint of film-forming properties of the substrate. The content of the lubricant according to the present embodiment is preferably 0.01 to 5.0% by mass, and more preferably 0.1 to 1.0% by mass, based on 100% by mass of the resin composition.

[0028] 1.1.4.3 Elastomers The elastomer according to the present embodiment is preferably a thermoplastic elastomer, and examples of the thermoplastic elastomer include urethane elastomers, olefin elastomers, chlorinated polyethylene elastomers, ethylene vinyl acetate elastomers, polyester elastomers, styrene elastomers, and polyamide elastomers. These may be used alone or in combination of two or more. Of these, chlorinated polyethylene is preferred from the viewpoint of tensile elongation at low temperatures (for example, −5° C. or lower). The content of the lubricant according to the present embodiment is preferably 0.1 to 15% by mass, and more preferably 1.0 to 10% by mass, when the resin composition is taken as 100% by mass.

[0029] 1.1.5 Substrate layer thickness The thickness of the substrate layer according to this embodiment is preferably 250 μm or less, more preferably 100 to 250 μm, and even more preferably 120 to 200 μm. The thickness of the substrate layer may be, for example, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, or 250 μm, or may be within a range between any two of the values ​​exemplified herein. The thickness of the substrate layer can be measured by a method conforming to JIS C2107:2011. Specifically, it can be the average value measured at multiple measurement points using a gauge. The thickness of the substrate layer may be measured on the substrate layer before the formation of the pressure-sensitive adhesive layer, or may be measured on the substrate layer from which the pressure-sensitive adhesive layer has been removed using a solvent after the production of the pressure-sensitive adhesive tape. When the thickness of the substrate layer is equal to or greater than the lower limit, the strength of the pressure-sensitive adhesive tape is improved. When the thickness of the substrate layer is equal to or less than the upper limit, the repulsive force when the substrate layer is wrapped around an electric wire or the like is reduced.

[0030] 1.2 Adhesive layer The pressure-sensitive adhesive layer according to this embodiment is a rubber-based pressure-sensitive adhesive layer. The rubber-based pressure-sensitive adhesive layer according to this embodiment contains a (meth)acrylic polymer. The rubber-based pressure-sensitive adhesive layer according to this embodiment preferably further contains a base polymer and a tackifier.

[0031] 1.2.1 (Meth)acrylic polymers The (meth)acrylic polymer according to this embodiment is a polymer containing structural units derived from alkyl (meth)acrylate. The alkyl (meth)acrylate according to this embodiment is preferably methyl (meth)acrylate, with methyl methacrylate being particularly preferred. The alkyl group of the alkyl (meth)acrylate according to this embodiment preferably has 18 or less carbon atoms, more preferably 1 to 8, and even more preferably 1 to 3. When the alkyl group of the alkyl (meth)acrylate has a carbon number within this range, the glass transition temperature of the (meth)acrylic polymer increases, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape. The (meth)acrylic polymer according to this embodiment has a content of structural units derived from alkyl (meth)acrylate of, for example, 60% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on a total of 100% by mass of the constituent monomer units. The (meth)acrylic polymer according to this embodiment may contain structural units derived from glycidyl (meth)acrylate, in addition to structural units derived from alkyl (meth)acrylate.

[0032] The glass transition temperature of the (meth)acrylic polymer according to this embodiment is, for example, 20 to 150°C, and more preferably 80 to 110°C. The glass transition temperature of the (meth)acrylic polymer may be, for example, 20, 30, 40, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 130, 140, or 150°C, or may be within a range between any two of the values ​​exemplified here. The glass transition temperature of the (meth)acrylic polymer in the pressure-sensitive adhesive layer can be measured by isolating the (meth)acrylic polymer from the pressure-sensitive adhesive layer. The glass transition temperature of the (meth)acrylic polymer can be measured, for example, by a method in accordance with JIS K 7121:2012, specifically, by differential scanning calorimetry (DSC). When the pressure-sensitive adhesive layer contains multiple types of (meth)acrylic polymers, the "glass transition temperature of the (meth)acrylic polymer" can be calculated as follows. For example, when (meth)acrylic polymer A having a glass transition temperature X accounts for a mass % and (meth)acrylic polymer B having a glass transition temperature Y accounts for b mass % (a+b=100) of 100 mass % of (meth)acrylic polymer, the "glass transition temperature of the (meth)acrylic polymer" in the present application can be calculated by the following formula. X×(a / 100)+Y×(b / 100) When the glass transition temperature of the (meth)acrylic polymer is equal to or higher than the lower limit, the adhesive strength of the adhesive tape is further improved. When the glass transition temperature of the (meth)acrylic polymer is equal to or lower than the upper limit, the compatibility is good and the workability is improved.

[0033] The content of the (meth)acrylic polymer in the rubber-based pressure-sensitive adhesive layer according to the present embodiment is, for example, 1 to 30% by mass, more preferably 5 to 25% by mass, and even more preferably 7 to 22% by mass. The content of the (meth)acrylic polymer in the rubber-based pressure-sensitive adhesive layer may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, or 30% by mass, or may be within a range between any two of the numerical values ​​exemplified here. When the content of the (meth)acrylic polymer is equal to or greater than the lower limit, the adhesive strength of the pressure-sensitive adhesive tape is further improved. When the content of the (meth)acrylic polymer is equal to or less than the upper limit, the hardness of the rubber-based pressure-sensitive adhesive layer becomes appropriate, and the adhesive strength of the pressure-sensitive adhesive tape is further improved. Furthermore, the pressure-sensitive adhesive tape exhibits excellent adhesive strength even at low temperatures (for example, −5° C. or lower).

[0034] 1.2.2 Base polymer The rubber-based pressure-sensitive adhesive layer according to this embodiment preferably further comprises a base polymer. Examples of the base polymer according to this embodiment include natural rubber, synthetic rubber, and modified natural rubber (a graft copolymer of natural rubber with at least one selected from the above synthetic rubbers and alkyl (meth)acrylates). Examples of the base polymer according to this embodiment include natural rubber, styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), hydrogenated products of the above styrene-based block copolymers (SIPS, SEBS), styrene-butadiene rubber (SBR), synthetic rubber such as polyisoprene rubber (IR), polyisobutylene (PIB), and butyl rubber (IIR), as well as a graft copolymer of natural rubber with at least one selected from the above synthetic rubbers and alkyl (meth)acrylates. These base polymers may be used alone or in combination of two or more. Synthetic Rubber: The base polymer according to this embodiment preferably comprises modified natural rubber, and a graft copolymer of natural rubber with alkyl (meth)acrylate is particularly preferred as the modified natural rubber. When modified natural rubber is used, the base polymer has excellent compatibility with the (meth)acrylic polymer.

[0035] The rubber-based pressure-sensitive adhesive layer according to the present embodiment preferably contains a natural rubber component. The content of the natural rubber component in the rubber-based pressure-sensitive adhesive layer according to the present embodiment is, for example, 1 to 20% by mass, preferably 2 to 15% by mass, and more preferably 5 to 12% by mass. The content of the natural rubber component in the rubber-based pressure-sensitive adhesive layer may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% by mass, or may be within a range between any two of the values ​​exemplified here. When the content of the natural rubber component is equal to or greater than the lower limit, the pressure-sensitive adhesive tape has excellent adhesive strength even at low temperatures (for example, −5°C or lower). When the content of the natural rubber component is equal to or less than the upper limit, the adhesive strength retention rate (described below) is further improved, resulting in a pressure-sensitive adhesive tape that is less likely to peel over a long period of time. In this specification, the term "natural rubber component" includes natural rubber and the natural rubber portion of modified natural rubber, and the "natural rubber component content" refers to the sum of the natural rubber content and the value calculated from the natural rubber content in the modified natural rubber. It is particularly preferable to use a natural rubber component and a synthetic rubber component in combination as the base polymer in this embodiment. The combined use of a synthetic rubber component improves the compatibility of the base polymer with the (meth)acrylic polymer, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape.

[0036] 1.2.3 Tackifiers The rubber-based pressure-sensitive adhesive layer according to this embodiment preferably contains a tackifier. The tackifier according to this embodiment can be selected taking into consideration the softening point and compatibility with each component. Examples of tackifiers according to this embodiment include emulsions of terpene resins, rosin resins, hydrogenated rosin resins, coumarone-indene resins, styrene-based resins, petroleum resins, terpene-phenol resins, xylene-based resins, and other aliphatic hydrocarbon resins or aromatic hydrocarbon resins. These tackifiers may be used alone or in combination of two or more. Petroleum resins and terpene-phenol resins are preferred tackifiers according to this embodiment, and a combination of petroleum resins and terpene-phenol resins is particularly preferred.

[0037] The content of the tackifier in the rubber-based pressure-sensitive adhesive layer according to this embodiment is preferably 40 to 60% by mass, and more preferably 45 to 55% by mass. The content of the tackifier in the rubber-based pressure-sensitive adhesive layer may be, for example, 40, 41, 42, 43, 44, 45, 50, 55, 56, 57, 58, 59, or 60% by mass, or may be within a range between any two of the values ​​exemplified here. When the tackifier content is within this range, the storage modulus of the rubber-based pressure-sensitive adhesive layer becomes an appropriate value, resulting in a pressure-sensitive adhesive tape that is less likely to peel over long periods of time. Furthermore, when the tackifier content is equal to or less than the upper limit, the side surfaces of the pressure-sensitive adhesive tape are less likely to become sticky even after long-term use.

[0038] The glass transition temperature of the tackifier in the rubber-based pressure-sensitive adhesive layer according to this embodiment is preferably 40 to 150° C. The glass transition temperature of the tackifier in the pressure-sensitive adhesive layer can be measured in the same manner as the glass transition temperature of the (meth)acrylic polymer in the pressure-sensitive adhesive layer described above. When the glass transition temperature of the tackifier in the rubber-based pressure-sensitive adhesive layer is in this range, the adhesive strength of the pressure-sensitive adhesive tape is further improved.

[0039] 1.2.4 Adhesive layer thickness The thickness of the pressure-sensitive adhesive layer according to this embodiment is preferably 10 to 40 μm, more preferably 15 to 35 μm, and even more preferably 20 to 35 μm. The thickness of the pressure-sensitive adhesive layer may be, for example, 10, 15, 20, 25, 30, 35, or 40 μm, or may be within a range between any two of the values ​​exemplified herein. The thickness of the pressure-sensitive adhesive layer can be measured, for example, by measuring the thickness of the pressure-sensitive adhesive tape using a method in accordance with JIS C2107:2011 and calculating the difference (absolute value) between the thickness of the pressure-sensitive adhesive tape and the thickness of the base layer measured using the above-mentioned method. When the thickness of the pressure-sensitive adhesive layer is equal to or greater than the lower limit, the adhesive strength of the pressure-sensitive adhesive tape is further improved. When the thickness of the pressure-sensitive adhesive layer is equal to or less than the upper limit, the pressure-sensitive adhesive tape is easily unwound when used in a roll, resulting in excellent tape unfoldability.

[0040] 1.2.5 Storage modulus of adhesive layer The storage modulus of the rubber-based pressure-sensitive adhesive layer according to the present embodiment at 23°C is, for example, 0.15 MPa or more, preferably 0.25 to 0.45 MPa, and more preferably 0.30 to 0.40 MPa. The storage modulus of the rubber-based pressure-sensitive adhesive layer at 23°C may be, for example, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, or 0.45 MPa, or may be within a range between any two of the values ​​exemplified herein. The storage modulus of the rubber-based pressure-sensitive adhesive layer at 23°C can be measured, for example, by scraping 0.1 g of the rubber-based pressure-sensitive adhesive layer from a pressure-sensitive adhesive tape, forming it into a sheet with a thickness of 1 mm, and using a dynamic elasticity modulus measuring device under the following conditions. Measurement start temperature: -60℃ Measurement end temperature: 120℃ Heating rate: 4°C / min Frequency: 1Hz When the storage modulus at 23°C of the rubber-based pressure-sensitive adhesive layer is equal to or greater than the lower limit, the adhesive strength of the pressure-sensitive adhesive tape is further improved, and the adhesive strength retention rate is further improved. When the storage modulus at 23°C of the rubber-based pressure-sensitive adhesive layer is equal to or less than the upper limit, the adhesive strength of the pressure-sensitive adhesive tape is further improved. Furthermore, when the storage modulus at 23°C of the rubber-based pressure-sensitive adhesive layer is equal to or less than the upper limit, the repulsive force when wrapped around an electric wire or the like is reduced, the adhesive strength retention rate is further improved, and the pressure-sensitive adhesive tape is therefore less likely to peel over a long period of time.

[0041] 1.3 Other Layers The pressure-sensitive adhesive tape according to the present embodiment may further include other layers within the range that does not impair the effects of the present invention. The pressure-sensitive adhesive tape according to the present embodiment may further include a primer layer between the substrate layer and the pressure-sensitive adhesive layer for the purpose of improving the adhesion between the substrate layer and the pressure-sensitive adhesive layer.

[0042] The primer for the primer layer according to this embodiment preferably contains a mixture of a graft polymer obtained by graft-polymerizing methyl methacrylate onto natural rubber and an acrylonitrile-butadiene copolymer. Furthermore, the primer is particularly preferably a mixture of the above mixture and a (meth)acrylic polymer used in the rubber-based pressure-sensitive adhesive layer. The mixing ratio of the mixture to the (meth)acrylic polymer can be, for example, 1:0.1 to 1:10 or 1:1 to 1:5. With such a primer composition, the polarity of the primer layer becomes closer to that of the pressure-sensitive adhesive layer, making peeling between the primer layer and the pressure-sensitive adhesive layer less likely to occur.

[0043] The graft polymer according to this embodiment is preferably one obtained by graft polymerizing 70 to 40% by mass of natural rubber with 30 to 60% by mass of methyl methacrylate. When the lower limit of the methyl methacrylate content is within this range, adhesion to the substrate layer is excellent and delamination is unlikely to occur. When the upper limit of the methyl methacrylate content is within this range, the primer itself is less likely to harden and is more likely to follow the deformation of the substrate layer, making delamination less likely to occur.

[0044] The acrylonitrile-butadiene copolymer according to this embodiment may be a medium nitrile type (25 to 30 mass% acrylonitrile, 75 to 70 mass% butadiene), a medium-high nitrile type (31 to 35 mass% acrylonitrile, 69 to 65 mass% butadiene), or a high nitrile type (36 to 43 mass% acrylonitrile, 64 to 57 mass% butadiene). These may be used alone or in combination of two or more. The content of the acrylonitrile-butadiene copolymer is preferably 25 to 300 parts by mass relative to 100 parts by mass of the graft polymer.

[0045] 2. Manufacturing method of adhesive tape The pressure-sensitive adhesive tape according to the present embodiment can be produced, for example, by laminating a pressure-sensitive adhesive layer on at least one surface of a base layer. Specifically, the method for producing the pressure-sensitive adhesive tape according to the present embodiment includes a base layer forming step and a pressure-sensitive adhesive layer forming step.

[0046] 2.1 Base material layer formation process The method for producing a pressure-sensitive adhesive tape according to the present embodiment includes a base layer forming step in which a base layer is formed using a polyvinyl chloride resin or a resin composition containing a polyvinyl chloride resin. The resin composition according to the present embodiment can be produced by melt-kneading the polyvinyl chloride resin, a plasticizer, and other additives in a mixer or the like so as to uniformly disperse them. The base layer according to the present embodiment can be produced by forming the polyvinyl chloride resin or the resin composition into a predetermined thickness using a calendering machine or the like. The temperature at this time can be set as desired depending on the components in the resin composition, and can be set, for example, to 100 to 200°C.

[0047] 2.2 Primer layer formation process The method for producing a pressure-sensitive adhesive tape according to this embodiment preferably further includes a primer layer-forming step. In the primer layer-forming step according to this embodiment, for example, a primer is applied to at least one surface of the substrate layer, and the solvent (e.g., moisture) is thoroughly removed in a drying oven. Examples of the primer application method include gravure, spray, kiss roll, bar, and knife methods.

[0048] 2.3 Adhesive layer formation process The method for producing a pressure-sensitive adhesive tape according to this embodiment includes a pressure-sensitive adhesive layer-forming step of forming a rubber-based pressure-sensitive adhesive layer on at least one surface of a substrate layer. When the method includes the primer layer-forming step, the pressure-sensitive adhesive layer-forming step refers to forming a rubber-based pressure-sensitive adhesive layer on at least one surface of the substrate layer via a primer layer. In the pressure-sensitive adhesive layer-forming step according to this embodiment, it is preferable to coat at least one surface of the substrate with an aqueous latex containing a rubber-based pressure-sensitive adhesive composition. Since all components of the rubber-based pressure-sensitive adhesive layer according to this embodiment are soluble in water, an aqueous solvent can be used. The use of an aqueous latex reduces residual solvent, which can occur when organic solvents are used, thereby suppressing adverse effects on the human body and reducing environmental impact. Examples of coating methods for the aqueous latex include the comma method, lip die method, gravure method, roll method, and slot die method. After coating the aqueous latex, the solvent (water) is thoroughly removed in a drying oven to obtain a pressure-sensitive adhesive tape.

[0049] 3. Characteristics of adhesive tape The adhesive tape according to this embodiment is resistant to peeling for a long period of time. To make an adhesive tape that is resistant to peeling for a long period of time, it is necessary for the adhesive tape to have high adhesive strength and for the adhesive strength to be maintained for a long period of time.

[0050] 3.1 Adhesion (normal, to SUS) The adhesive strength (normal, to SUS) of the adhesive tape according to this embodiment is preferably 1.8 N / 10 mm or more, more preferably 1.9 N / 10 mm or more, and even more preferably 2.0 N / 10 mm or more. The adhesive strength (normal, to SUS) of the adhesive tape according to this embodiment is preferably 4.0 N / 10 mm or less. The adhesive strength (normal, to SUS) of the adhesive tape according to this embodiment is preferably 1.8 to 4.0 N / 10 mm, more preferably 1.9 to 3.5 N / 10 mm, and even more preferably 2.0 to 3.0 N / 10 mm. The adhesive strength (normal, to SUS) can be measured, for example, using a SUS plate as the test plate according to a method in accordance with JIS Z0237:2000. When the adhesive strength (normal, to SUS) of the adhesive tape is equal to or greater than the lower limit, the adhesive strength is excellent and the tape can be suitably used in operational machinery or components for machinery. When the adhesive strength (normal, to SUS) of the adhesive tape is not more than the upper limit, the tape becomes easier to unwind when used in a roll, the adhesive tape has excellent unfoldability, and workability is improved. Methods for improving the adhesive strength (normal, to SUS) of the adhesive tape include, for example, adjusting the content of structural units derived from alkyl (meth)acrylate in the (meth)acrylic polymer, the number of carbon atoms in the alkyl group, and the glass transition temperature, adjusting the glass transition temperature of the tackifier, adjusting the content of the (meth)acrylic polymer and natural rubber component in the rubber-based adhesive layer, increasing the thickness of the adhesive layer, and adjusting the storage modulus within an appropriate range, and particularly including the method of increasing the thickness of the adhesive layer and adjusting the storage modulus within an appropriate range.

[0051] 3.2 Adhesion (normal, against SUS, after storage at 60°C for 10 days) The adhesive strength of the pressure-sensitive adhesive tape according to this embodiment (normal, to SUS, after storage at 60°C for 10 days) is preferably 1.6 N / 10 mm or more, more preferably 1.7 N / 10 mm or more, and even more preferably 1.8 N / 10 mm or more. Furthermore, the adhesive strength of the pressure-sensitive adhesive tape according to this embodiment (normal, to SUS, after storage at 60°C for 10 days) is preferably 4.0 N / 10 mm or less. The adhesive strength of the pressure-sensitive adhesive tape according to this embodiment (normal, to SUS, after storage at 60°C for 10 days) is preferably 1.6 to 4.0 N / 10 mm, more preferably 1.7 to 3.0 N / 10 mm, and even more preferably 1.8 to 2.5 N / 10 mm. The adhesive strength (normal, to SUS, after storage at 60°C for 10 days) can be measured, for example, after storing the pressure-sensitive adhesive tape in a 60°C atmosphere for 10 days, in the same manner as for the adhesive strength (normal, to SUS) described above. When the adhesive strength of the adhesive tape (normal, to SUS, after 10 days storage at 60°C) is at or above the lower limit, the adhesive tape will have excellent adhesive strength and will not peel off for a long period of time (e.g., several years). When the adhesive strength of the adhesive tape (normal, to SUS, after 10 days storage at 60°C) is at or below the upper limit, the tape will be easy to unwind when used in a roll, resulting in excellent unfoldability and improved workability. Methods for improving the adhesive strength of the adhesive tape (normal, to SUS, after 10 days storage at 60°C) include, for example, adjusting the base polymer composition in the rubber-based adhesive layer, increasing the content of (meth)acrylic polymer, adding a tackifier, or using a (meth)acrylic polymer with a higher glass transition temperature. In particular, methods such as reducing the content of rubber components (particularly natural rubber and modified natural rubber), increasing the content of (meth)acrylic polymer, or using a (meth)acrylic polymer with a higher glass transition temperature are exemplified.

[0052] 3.3 Adhesion retention rate (60°C, 10 days) The adhesive retention rate (60°C, 10 days) of the adhesive tape according to this embodiment is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. The adhesive retention rate can be calculated, for example, from the following formula (1) when the adhesive strength (normal, to SUS) measured by the above-mentioned method is V1 and the adhesive strength (normal, to SUS, after storage at 60°C for 10 days) is V2. Adhesive force maintenance rate (%)=V2 / V1×100 (1) The higher the adhesion retention rate (60°C, 10 days), the less likely the adhesive tape will peel over a long period of time (e.g., several years). Methods for improving the adhesion retention rate (60°C, 10 days) include, for example, a method of reducing the content of natural rubber components in the rubber-based adhesive layer, and a method of adjusting the storage modulus of the adhesive layer to an appropriate range, and particularly a method of reducing the content of natural rubber components in the rubber-based adhesive layer.

[0053] 4 How to use The pressure-sensitive adhesive tape according to this embodiment can be used to bind electric wires. Accordingly, one embodiment of the present invention is a pressure-sensitive adhesive tape for bundling electric wires. The pressure-sensitive adhesive tape according to this embodiment can be used in various mechanical devices such as automobiles, aircraft, trains, factory automation equipment, home appliances, office automation equipment, medical equipment, communications equipment, and play equipment, or in components for such mechanical devices. The pressure-sensitive adhesive tape according to this embodiment has high adhesive strength and is resistant to peeling over a long period of time, and therefore can be particularly suitably used in operating mechanical devices such as automobiles, aircraft, trains, factory automation equipment, home appliances, and play equipment, or in components for such mechanical devices. [Example]

[0054] The present invention will be described in more detail below with reference to examples. Note that the examples described below are representative examples of the present invention and should not be construed as narrowing the scope of the present invention.

[0055] <Base material layer formation process> A resin composition was prepared by melt-kneading 55 parts by weight of polyvinyl chloride resin, 36 parts by weight of plasticizer, 3.5 parts by weight of stabilizer, 0.5 parts by weight of lubricant, and 5 parts by weight of elastomer in a Banbury mixer until uniformly dispersed. The resulting resin composition was then calendered at a roll temperature of 173°C to prepare a substrate layer.

[0056] <Primer layer forming process> A primer was gravure coated onto one side of each substrate layer, and the moisture was thoroughly removed in a drying oven to form a primer layer. After drying, the primer layer had a thickness of 0.3 μm.

[0057] <Adhesive forming process> The rubber-based pressure-sensitive adhesive compositions having the formulations shown in Tables 1 to 3 were dissolved in water to prepare aqueous latexes containing the rubber-based pressure-sensitive adhesive compositions. The aqueous latex containing the rubber-based pressure-sensitive adhesive composition was applied onto a primer layer using the comma method (i.e., the aqueous latex containing the rubber-based pressure-sensitive adhesive composition was applied to one side of the substrate layer via the primer layer), and the moisture was thoroughly removed in a drying oven to prepare pressure-sensitive adhesive tapes. The pressure-sensitive adhesive tapes of Examples and Comparative Examples prepared in this manner were subjected to the tests and evaluations described below, and the results are shown in Tables 1 to 3. The thicknesses of the substrate layer and the pressure-sensitive adhesive layer were measured using a thickness gauge (manufactured by Mitutoyo Corporation) according to the method of JIS C2107:2011 (n=5).

[0058] The components used to obtain the resin composition are as follows: Polyvinyl chloride resin: Polyvinyl chloride resin 1300: Taiyo PVC "TH-1300", average polymerization degree 1300 Plasticizer: TOTM: "TOTM" manufactured by J-Plus Corporation, Trioctyl Trimellitate Stabilizers: Metallic compound stabilizer: Sakai Chemical Industry Co., Ltd. "OW-5200" Lubricant: Stearic acid: "Sakura Stearic Acid" manufactured by NOF Corporation Elastomer: Chlorinated polyethylene: Elaslen (registered trademark) 301MA manufactured by Resonac Co., Ltd.

[0059] The components used to prepare the primer layer were as follows: Primer: A 1:3 mixture of a graft polymer latex (methyl methacrylate grafted onto natural rubber) and an acrylonitrile-butadiene copolymer emulsion (E-Tech Co., Ltd.'s "KT4612A") and a (meth)acrylic polymer (Toyochem Co., Ltd.'s "E277")

[0060] The components used to prepare the pressure-sensitive adhesive layer are as follows. In the tables, "SBR" stands for "styrene-butadiene rubber" and "Tg" stands for "glass transition temperature." The formulations shown in Tables 1 to 3 are values ​​converted into solid content. Base Polymer: Natural rubber: "HA LATEX" manufactured by Resitex Co., Ltd. Modified natural rubber: "MG-40S" manufactured by Resitex Co., Ltd., a graft copolymer of natural rubber and methyl methacrylate, with a natural rubber content of 70% by mass. SBR-1 (styrene-butadiene rubber 1): "T-093A" manufactured by JSR Corporation SBR-2 (Styrene-Butadiene Rubber 2): JSR Corporation "0533" SBR-3 (styrene-butadiene rubber 3): E-Tech Co., Ltd. "KT-4615B"

[0061] (Meth)acrylic polymer: A-1: "E277" manufactured by Toyochem Co., Ltd., 100% content of structural units derived from methyl (meth)acrylate (alkyl group carbon number 1), glass transition temperature 91°C A-2: "AE162" manufactured by E-Tech Co., Ltd., 100% of the structural unit is derived from alkyl (meth)acrylate, and the glass transition temperature is 92°C. A-3: "AE703" manufactured by E-Tech Co., Ltd., 100% content of structural units derived from alkyl (meth)acrylate, glass transition temperature 54°C A-4: "TOCRYL (registered trademark) BCX-8104" manufactured by Artience Co., Ltd., 100% content of structural units derived from alkyl (meth)acrylate, glass transition temperature 29°C

[0062] Tackifier: Petroleum resin-1: Arakawa Chemical Industries, Ltd. "AP-1100", glass transition temperature 60°C Petroleum resin-2: Arakawa Chemical Industries, Ltd. "AP-2100", glass transition temperature 50°C. Terpene-phenol resin: Arakawa Chemical Industries, Ltd. "E200", glass transition temperature 98°C.

[0063] <Adhesion (normal, against SUS)> Using a SUS plate as the test plate, the measurement was performed according to a method conforming to JIS Z0237: 2000. For the measurement, a bench-top precision universal testing machine ("Autograph (registered trademark) AGS-1kNX" manufactured by Shimadzu Corporation) was used, and the average value of multiple measurements (n = 5) was calculated.

[0064] <Adhesion strength (normal, against SUS, after storage at 60°C for 10 days)> The adhesive tape was stored in an atmosphere at 60°C for 10 days, and then the adhesive strength was measured in the same manner as above.

[0065] <Adhesion retention rate (60°C, 10 days)> The adhesive strength (normal, against SUS) measured by the above method was designated as V1, and the adhesive strength (normal, against SUS, after storage at 60°C for 10 days) was designated as V2, and the value was calculated using the following formula (1). Adhesive force maintenance rate (%)=V2 / V1×100 (1)

[0066] <Storage modulus of adhesive layer> 0.1 g of the rubber adhesive layer was scraped off from the adhesive tape and formed into a 1 mm thick sheet to be used as a sample for measuring storage modulus. This sample was measured using a dynamic modulus measuring device (TA Instruments Japan, Inc., "ARES") under the following conditions. Measurement start temperature: -60℃ Measurement end temperature: 120℃ Heating rate: 4°C / min Frequency: 1Hz

[0067] <Wire winding ability> Ten heat-resistant automotive wires ("AVX050," manufactured by Sumitomo Wiring Systems, Ltd., diameter: 50 mm) were cut to lengths of 800 mm, and four heat-resistant automotive wires ("AVX085," manufactured by Sumitomo Wiring Systems, Ltd., diameter: 85 mm) were cut to lengths of 800 mm. These 14 wires were bundled together and fixed together at both longitudinal ends with adhesive tape to facilitate winding. Then, an adhesive tape (19 mm wide) of each Example or Comparative Example was wrapped around the wires in a half-wrap manner with the adhesive layer facing inward to prepare an evaluation sample. Here, "half-wrap winding" refers to wrapping the adhesive tape around the wire so that half of the width of the adhesive tape overlaps half of the width of the adhesive tape already wrapped around it. Each evaluation sample was evaluated according to the following criteria. A: No peeling was observed. B: Minor peeling (distance from the edge of the film to the peeling edge of the film of less than 1.0 mm) was observed. C: Peeling was observed (peel distance from the edge was 1.0 mm or more).

[0068] <Long-term storage> The pressure-sensitive adhesive tape was stored in an atmosphere of 40° C. for 100 days, and then the above-mentioned wire winding test was carried out. Each evaluation sample was evaluated according to the following criteria. A: No peeling was observed. B: Minor peeling (distance from the edge of the film to the peeling edge of the film of less than 1.0 mm) was observed. C: Peeling was observed (peel distance from the edge was 1.0 mm or more).

[0069] [Table 1]

[0070] [Table 2]

[0071] Table 3

Claims

1. An adhesive tape comprising a base layer containing a polyvinyl chloride resin and a rubber-based adhesive layer provided on at least one surface of the base layer, the rubber-based pressure-sensitive adhesive layer contains a (meth)acrylic polymer, The adhesive tape has an adhesive strength V measured at 23°C by a method in accordance with JIS Z0237:2000. １ is 1.8 to 4.0 N / 10 mm, The adhesive strength V measured after storing the adhesive tape in an atmosphere at 60°C for 10 days ２ and V １ The adhesive strength retention rate calculated from the following formula (1) based on the above formula is 90% or more. Adhesion retention rate (%) = V ２ / V １ ×100 (1) Adhesive tape.

2. The pressure-sensitive adhesive tape according to claim 1, wherein the content of the natural rubber component in the rubber-based pressure-sensitive adhesive layer is 2 to 15 mass %.

3. The pressure-sensitive adhesive tape according to claim 1, wherein the (meth)acrylic polymer has a glass transition temperature of 80 to 110°C.

4. The pressure-sensitive adhesive tape according to claim 1 , wherein a content of structural units derived from alkyl (meth)acrylate in a total of 100% by mass of monomer units constituting the (meth)acrylic polymer is 60% by mass or more.

5. the rubber-based pressure-sensitive adhesive layer further contains a modified natural rubber, 2. The pressure-sensitive adhesive tape according to claim 1, wherein the modified natural rubber is a graft copolymer of natural rubber and alkyl (meth)acrylate.

6. The pressure-sensitive adhesive tape according to claim 1, wherein the content of the (meth)acrylic polymer in the rubber-based pressure-sensitive adhesive layer is 5 to 25% by mass.

7. the rubber-based pressure-sensitive adhesive layer further contains a tackifier, The pressure-sensitive adhesive tape according to claim 1, wherein the content of the tackifier in the rubber-based pressure-sensitive adhesive layer is 40 to 60 mass %.

8. 2. The pressure-sensitive adhesive tape according to claim 1, wherein the rubber-based pressure-sensitive adhesive layer has a storage modulus at 23° C. of 0.25 to 0.45 MPa.

9. 2. The pressure-sensitive adhesive tape according to claim 1, wherein the rubber-based pressure-sensitive adhesive layer has a thickness of 10 to 40 μm.

10. The pressure-sensitive adhesive tape according to any one of claims 1 to 9, which is used for bundling electric wires.

11. A method for producing the adhesive tape according to any one of claims 1 to 9, comprising: a pressure-sensitive adhesive layer forming step of forming the rubber-based pressure-sensitive adhesive layer on at least one surface of the base material layer, The method for producing a pressure-sensitive adhesive tape, wherein the pressure-sensitive adhesive layer forming step comprises applying an aqueous latex containing a rubber-based pressure-sensitive adhesive composition to at least one surface of the substrate layer.

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