Adhesive tape and method for producing same

Abstract

The invention provides an adhesive tape which is excellent in light weight, good in base material strength and adhesive force, and excellent in base material state. According to the present invention, provided is an adhesive tape provided with a base material comprising a resin composition containing a thermoplastic resin and an adhesive layer provided on at least one surface of the base material, the base material having a TD shrinkage rate of-5.0 to 0% under conditions of heating at 110 DEG C for 5 minutes, and the base material having an MD shrinkage rate of 0 to 15% under conditions of heating at 110 DEG C for 5 minutes, the TD shrinkage rate being-5.0 to 0% under conditions of heating at 110 DEG C for 5 minutes, and the MD shrinkage rate being-5.0 to 0% under conditions of heating at 110 DEG C for 5 minutes. The thickness of the base material is 25-65 [mu] m, the thickness of the adhesive layer is 0.5-12.0 [mu] m, the melt viscosity of the base material at 175 DEG C at a shear speed of 250 sec <-1 > is 300-1,300 Pa.s, and the melt tension of the base material at 175 DEG C at a traction speed of 1.0 m / min is 0.01-0.10 N.

Description

[Technical field]

[0001] The present invention relates to an adhesive tape and a method for manufacturing the same. [Background Technology]

[0002] As various adhesive films such as insulating tapes for various electrical equipment in automobiles, railways, aircraft, ships, houses, factories, etc., adhesive tapes having an adhesive coated on one side and a base material made of a resin composition containing a thermoplastic resin are used because they have moderate flexibility and elongation, excellent flame retardancy, mechanical strength, heat deformation resistance, electrical insulation, and moldability, and are relatively inexpensive (Patent Documents 1 and 2). [Prior Art Document] [Patent Document]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 11-209718 [Patent Document 2] International Publication No. 2019 / 049565 [Summary of the invention] [Problems to be Solved by the Invention]

[0004] In recent years, there has been a demand for lighter adhesive tapes, specifically thinner substrates and adhesives, for example, to improve fuel efficiency in automobiles and airplanes. However, thinning the substrate can reduce substrate strength, resulting in insufficient bundling properties for cables and other electrical wires.

[0005] The present invention has been made in view of the above circumstances and aims to provide an adhesive tape having excellent lightness, that is, a thin base material and adhesive thickness, and having base material strength and adhesive force for bundling electric wires such as cables, and an excellent base material state. [Technical solutions to solve the problem]

[0006] Through research conducted by the present inventors, it was found that an adhesive tape having excellent lightness, good substrate strength and adhesive force, and excellent substrate condition can be obtained by preparing the following adhesive tape, wherein the adhesive tape comprises: a substrate composed of a resin composition containing a thermoplastic resin, and an adhesive layer provided on at least one side of the substrate, the TD shrinkage of the substrate under heating conditions of 110°C for 5 minutes is -5.0 to 0%, the MD shrinkage of the substrate under heating conditions of 110°C for 5 minutes is 0 to 15%, the thickness of the substrate is 25 to 65 μm, the thickness of the adhesive layer is 0.5 to 12.0 μm, the substrate is heated at 175°C and a shear rate of 250 sec -1 The melt viscosity is 300 to 1,300 Pa·s, and the melt tension of the substrate is 0.01 to 0.10 N at 175° C. and a pulling speed of 1.0 m / min. That is, the present invention relates to the following. [1] An adhesive tape comprising: A substrate composed of a resin composition containing a thermoplastic resin, and an adhesive layer provided on at least one side of the substrate, The TD shrinkage of the above substrate under heating conditions of 110°C for 5 minutes is -5.0% to 0%. The MD shrinkage of the above substrate is 0-15% under the heating condition of 110°C for 5 minutes. The thickness of the substrate is 25 to 65 μm. The thickness of the adhesive layer is 0.5 to 12.0 μm. The substrate was heated at 175°C and a shear rate of 250 sec -1 The melt viscosity is 300 to 1,300 Pa·s. The melt tension of the substrate at 175° C. and a pulling speed of 1.0 m / min is 0.01 to 0.10 N. [2] The adhesive tape according to [1], wherein the storage elastic modulus of the substrate when subjected to dynamic viscoelasticity measurement in a shear mode at a temperature of 175°C and an angular frequency of 0.1 rad / s is 20.0 to 70.0 kPa. [3] The adhesive tape according to [1] or [2], wherein the tensile strength of the substrate is measured according to the conditions of "Item 8 'Tensile strength and elongation at break'" of JIS C 2107, and the tensile modulus is calculated from the result using the following formula, and the tensile modulus is 2 to 3500 MPa: Tensile elastic modulus (MPa) = [tensile stress (MPa) measured at a strain of 0.02 - tensile stress (MPa) measured at a strain of 0.015] / 0.005. [4] The adhesive tape according to any one of [1] to [3], wherein the thermoplastic resin is a polyvinyl chloride resin, and the average degree of polymerization of the polyvinyl chloride resin is 500 to 2,000. [5] The adhesive tape according to any one of [1] to [4], wherein the resin composition contains 20 to 75 parts by mass of a plasticizer and 30 parts by mass or less of a filler per 100 parts by mass of the thermoplastic resin. [6] The adhesive tape according to [5], wherein the average particle size of the filler is 0.3 μm or less. [7] The adhesive tape according to [5] or [6], wherein the plasticizer comprises at least one selected from trimellitic acid ester plasticizers, phthalic acid ester plasticizers, and adipate plasticizers. [8] The adhesive tape according to any one of [1] to [7], wherein the adhesive layer contains a tackifier. [9] The adhesive tape according to [8], wherein the tackifier contains a petroleum resin.

[10] The adhesive tape according to any one of [1] to [9], wherein the adhesive layer comprises a graft copolymer of an alkyl (meth)acrylate and at least one rubber component selected from natural rubber and synthetic rubber.

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

[10] , wherein the thickness of the substrate is 40 to 60 μm.

[12] The adhesive tape according to any one of [1] to

[11] , wherein the thickness of the adhesive layer is 2.0 to 10.0 μm.

[13] The adhesive tape according to any one of [1] to

[12] , which is used for bundling electric wires.

[14] An electric wire bundled with the adhesive tape as described in

[13] .

[15] A method for producing the adhesive tape according to any one of [1] to

[12] , comprising the following steps: stretching the resin composition comprising the thermoplastic resin in the MD at a stretching ratio of 3.5 times or less to obtain a substrate; and Disposing the adhesive layer on at least one side of the substrate; In the step of obtaining the substrate, the temperature of the resin composition immediately before stretching is 165° C. or higher. [Effects of the Invention]

[0007] According to the present invention, there can be provided a pressure-sensitive adhesive tape having excellent lightness, good substrate strength and adhesive force, and excellent substrate condition. [Specific implementation method]

[0008] <Explanation of terms> In the present specification, for example, the description "A to B" means A or more and B or less.

[0009] The following describes the embodiments of the present invention in detail. The present invention is not limited thereto and various modifications can be made without departing from the scope of the present invention. The various features shown in the embodiments shown below can be combined with each other. In addition, each feature independently establishes the invention. Furthermore, the MD of the substrate and the adhesive tape of the present invention refers to the feed direction (Machine Direction) of the film on the production line of the substrate and the adhesive tape, and the TD of the substrate and the adhesive tape refers to the direction orthogonal to the MD in the plane of the substrate and the adhesive tape (Transverse Direction).

[0010] <Adhesive Tape Structure> The pressure-sensitive adhesive tape according to one embodiment of the present invention comprises a substrate and a pressure-sensitive adhesive layer formed on one surface of the substrate.

[0011] <Base material> The substrate of one embodiment of the present invention is composed of a resin composition containing a thermoplastic resin. The resin composition may contain, in addition to the thermoplastic resin, for example, a plasticizer, a filler, and other additives.

[0012] As the thermoplastic resin of one embodiment of the present invention, for example, polyvinyl chloride resin, polyester resin, polyimide resin, polyamide resin, and polyolefin resin can be cited. These thermoplastic resins can be used alone or in combination of two or more. The thermoplastic resin of one embodiment preferably includes a vinyl chloride resin. The thermoplastic resin, for example, contains 80% by mass or more of vinyl chloride resin in a total of 100% by mass of the thermoplastic resin, preferably contains 90% by mass or more, and more preferably consists only of vinyl chloride resin (100% by mass). Polyvinyl chloride resin is preferred from the perspective of wire bundling applications because of its excellent insulation and wire bundling properties (flexibility and elasticity).

[0013] <Polyvinyl chloride resin> The polyvinyl chloride resin of one embodiment of the present invention is preferably a polyvinyl chloride resin having an average degree of polymerization of 500 to 2,000, and more preferably a polyvinyl chloride resin having an average degree of polymerization of 700 to 1,800. Furthermore, two or more polyvinyl chloride resins having different average degrees of polymerization may be used as the polyvinyl chloride resin. If the average degree of polymerization is less than 500, there may be a case where the polymer chains are not intertwined enough, and sufficient strength (wear resistance) cannot be obtained. If the average degree of polymerization is higher than 2,000, there may be a case where gelation is difficult, film forming properties deteriorate, and the substrate state deteriorates.

[0014] Plasticizers The plasticizer of one embodiment of the present invention is not particularly limited, as long as it can impart flexibility to the substrate. Examples thereof include trimellitate plasticizers, adipate plasticizers, phthalate plasticizers, epoxy plasticizers, isophthalate plasticizers, terephthalate plasticizers, and phosphoric acid plasticizers. From the perspective of plasticizing the thermoplastic resin or reducing oozing, trimellitate plasticizers, phthalate plasticizers, and adipate plasticizers are preferred. These plasticizers may be used alone or in combination of two or more.

[0015] <Trimellitate plasticizer> The trimellitic acid ester is preferably a trialkyl trimellitic acid ester (tri(C4-11 alkyl) trimellitic acid ester) represented by Formula 1. In Formula 1, n is preferably 5-10, more preferably 6-9, and even more preferably 8. [Chemistry 1]

[0016] Examples of tri(C4-11 alkyl) trimellitate include tributyl trimellitate, trihexyl trimellitate, tri-n-octyl trimellitate, tri-isooctyl trimellitate, tri-2-ethylhexyl trimellitate, and trinonyl trimellitate. Tri-n-octyl trimellitate is particularly preferred from the perspectives of plasticization efficiency, elongation of the substrate, and heat resistance. The molecular weight of trimellitate is preferably, for example, 378 to 672, more preferably 420 to 630, and even more preferably 462 to 588. These plasticizers may be used alone or in combination of two or more.

[0017] <Phthalate plasticizers> Phthalate-based plasticizers according to one embodiment of the present invention include, for example, DINP (diisononyl phthalate), DHP (diheptyl phthalate), DOP (di-2-ethylhexyl phthalate), n-DOP (di-n-octyl phthalate), and diisodecyl phthalate (DIDP). From the perspective of having a plasticizing effect on polyvinyl chloride resins or having less oozing out and having less impact on the human body, diesters of phthalic acid and alcohols having 9 to 10 carbon atoms, such as DINP (diisononyl phthalate) and diisodecyl phthalate (DIDP), are preferred. From the perspective of plasticizing efficiency, diisononyl phthalate is particularly preferred. These plasticizers may be used alone or in combination of two or more.

[0018] Adipate plasticizers Examples of adipate plasticizers according to one embodiment of the present invention include adipic acid-propylene glycol polyesters and adipic acid-butylene glycol polyesters. From the perspective of heat resistance, adipic acid polyesters are preferred. The weight-average molecular weight of the adipate is preferably 1,000 to 4,100, more preferably 1,600 to 4,100, and even more preferably 2,000 to 4,100. These plasticizers may be used alone or in combination of two or more.

[0019] <Plasticizer Content> The resin composition constituting the substrate of one embodiment of the present invention preferably contains 20 to 75 parts by mass of a plasticizer relative to 100 parts by mass of the thermoplastic resin, more preferably 25 to 65 parts by mass, and even more preferably 30 to 55 parts by mass. The content of the plasticizer is, for example, preferably 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, or 75 parts by mass relative to 100 parts by mass of the thermoplastic resin, and may also be within a range between any two of the values ​​exemplified herein. By making the plasticizer 25 parts by mass or more, the substrate can be made flexible. By making the plasticizer 75 parts by mass or less, the substrate can be made elastic. When a plasticizer is used in combination, the content of the plasticizer refers to the total amount of the plasticizers used in combination.

[0020] Fillers In the film-forming step of substrate production, the filler of one embodiment of the present invention is not particularly limited, as long as it is a filler that can easily peel the substrate from the calendering roll. For example, from the perspective of taking into account the favorable effects (reinforcement effect and flexibility), inorganic fillers are preferred.

[0021] <Inorganic fillers> As the inorganic filler of one embodiment of the present invention, for example, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, calcium hydroxide, potassium hydroxide, barium hydroxide, triphenyl phosphite, ammonium polyphosphate, polyphosphoric acid amide, zirconium oxide, magnesium oxide, zinc oxide, titanium oxide, molybdenum oxide, guanidine phosphate, hydrotalcite, montmorillonite, zinc borate, anhydrous zinc borate, zinc metaborate, barium metaborate, antimony oxide, antimony pentoxide, red phosphorus, talc, aluminum oxide, silicon dioxide, boehmite, bentonite, sodium silicate, calcium silicate, calcium sulfate, magnesium carbonate, carbon black. With regard to the viewpoint of taking into account reinforcement effect and flexibility, calcium carbonate is preferably used. These fillers can be used alone or in combination of two or more.

[0022] The content of the filler of one embodiment of the present invention is preferably 30 parts by mass or less, more preferably 20 parts by mass or less relative to 100 parts by mass of the thermoplastic resin. Specifically, for example, it is preferably 1, 5, 10, 15, 20, 25, or 30 parts by mass, or it may be within the range between any two of the numerical values ​​exemplified herein. By containing the filler, it is easy to peel the substrate from the calendering roll during the film-forming step of substrate manufacturing, which is advantageous in terms of manufacturing cost. However, if the content of the filler exceeds 30 parts by mass, pinholes may be generated in the substrate, which is therefore undesirable. When a filler is used in combination, the content of the filler refers to the total amount of the fillers used in combination.

[0023] <Average particle size of filler> The average particle size of the filler according to one embodiment of the present invention is preferably 0.3 μm or less, and more preferably 0.2 μm or less. By setting the average particle size to 0.3 μm or less, pinholes during film formation can be suppressed. The average particle size of the filler refers to the particle size at which the cumulative value of the volume-based cumulative particle size distribution, measured using a laser diffraction particle size distribution analyzer, reaches 50%. The cumulative particle size distribution is plotted as a distribution curve with particle size (μm) on the horizontal axis and cumulative value (%) on the vertical axis.

[0024] <Other additives contained in the resin composition> The resin composition of the present embodiment may contain other additives such as a colorant, a stabilizer, an antioxidant, an ultraviolet absorber, and a lubricant as needed within a range not impairing the effects of the present invention.

[0025] Examples of the stabilizer include metal soaps (metal-based composite stabilizers), etc. By including a stabilizer such as a metal soap, the thermal stability of the substrate can be easily improved. As a metal composite stabilizer, for example, at least one selected from fatty acid calcium, fatty acid zinc, and fatty acid barium can be cited. As the fatty acid component of the metal composite stabilizer, for example, lauric acid, stearic acid, ricinoleic acid, etc. can be cited. As a specific example of such a metal composite stabilizer, for example, calcium laurate, calcium stearate, calcium laurate, calcium stearate, calcium ricinoleate, zinc laurate, zinc ricinoleate, zinc stearate, barium laurate, barium stearate, barium ricinoleate, etc. are preferably used. These can be used alone or in combination of two or more. Furthermore, with respect to the viewpoint of being easy to further improve the thermal stability effect by combination, it is preferred to use a Ca-Zn metal stabilizer comprising fatty acid calcium and fatty acid zinc.

[0026] In one embodiment, the ratio of the metal composite stabilizer contained in the substrate is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass, relative to 100 parts by mass of the polyvinyl chloride resin. In another embodiment, when the total mass of the substrate resin composition is set to 100% by mass, the ratio of the metal composite stabilizer to the total mass of the substrate resin composition is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass.

[0027] Examples of lubricants include: higher fatty acids such as stearic acid and palmitic acid; higher alcohols such as palmityl alcohol and stearyl alcohol; higher fatty acid metal salts such as calcium stearate, zinc stearate, barium stearate, aluminum stearate, magnesium stearate, and sodium palmitate; higher fatty acid esters such as butyl stearate and glycerol monostearate; and higher fatty acid amides such as oleamide, stearamide, and erucamide. Here, "higher" means having 9 or more carbon atoms, preferably 9 to 30. These may be used alone or in combination of two or more. Of these, stearic acid is preferably included from the perspective of substrate film formation.

[0028] When the total mass of the resin composition for a substrate is set to 100 mass%, the ratio of the lubricant in the substrate is preferably 1 mass% or less, and more preferably 0.5 mass% or less.

[0029] <Substrate shrinkage in TD> The TD shrinkage of the substrate according to one embodiment of the present invention, when heated at 110°C for 5 minutes, is -5.0 to 0.0%, preferably -4.0 to 0.0%, and more preferably -3.0 to 0.0%. Specifically, for example, it is -5.0, -4.0, -3.0, -2.0, -1.0, or 0.0%, and may be within a range between any two of the values ​​exemplified herein. The closer the TD shrinkage is to 0%, the better the coating stability of the adhesive on the substrate and the better the substrate condition, which is preferred. In terms of coating stability of the adhesive on the substrate, the TD shrinkage is preferably -5.0% as the lower limit.

[0030] The TD shrinkage of the substrate under heating conditions of 110° C. for 5 minutes can be controlled, for example, by setting the MD stretching ratio in the film forming step of substrate production to 3.5 times or less. Alternatively, a 50 mm square film can be heated in an oven at 110°C for 5 minutes, and then the TD side length can be measured. The TD shrinkage of the substrate under heating conditions at 110°C for 5 minutes can be calculated using the following formula. TD heating shrinkage (%) = [50 - TD side length after heating (mm)] / 50 × 100

[0031] <Substrate shrinkage in MD> The MD shrinkage of the substrate according to one embodiment of the present invention, when heated at 110°C for 5 minutes, is 0.0 to 15.0%, preferably 0.0 to 10.0%, and more preferably 0.0 to 5.0%. Specifically, for example, it is 0.0, 2.0, 4.0, 6.0, 8.0, 9.0, 10.0, 12.0, 14.0, or 15.0%, and may be within a range between any two of the values ​​exemplified herein. The closer the MD shrinkage is to 0%, the better the coating stability of the adhesive on the substrate and the better the substrate condition, which is preferred. In terms of coating stability of the adhesive on the substrate, the MD shrinkage is preferably set to 15.0% as the upper limit.

[0032] The MD shrinkage of the substrate under heating conditions at 110° C. for 5 minutes can be controlled, for example, by setting the MD stretching ratio in the film forming step of substrate production to 3.5 times or less. Alternatively, a 50 mm square film can be heated in an oven at 110°C for 5 minutes, and then the MD side length can be measured. The MD shrinkage of the substrate under heating conditions at 110°C for 5 minutes can be calculated using the following formula. MD heating shrinkage (%) = [50 - MD side length after heating (mm)] / 50 × 100

[0033] <Melt viscosity of base material> The substrate of one embodiment of the present invention is heated at 175°C and a shear rate of 250 sec -1 The melt viscosity is 300 to 1,300 Pa·s, preferably 400 to 1,100 Pa·s, and more preferably 500 to 800 Pa·s. Specifically, it is 300, 500, 700, 900, 1,100, or 1,300 Pa·s, and may be within a range between any two of the values ​​exemplified here. A melt viscosity of 300 Pa·s or higher facilitates peeling the substrate from the calender rolls during the film-forming step of substrate production. Furthermore, uneven stretching due to excessively soft resins can be reduced, making MD stretching control easier. Furthermore, a melt viscosity of 1,300 Pa·s or lower allows the gap between the calender rolls to be appropriately narrowed during the film-forming step of substrate production, making MD stretch ratio control easier. Furthermore, the resin can be thoroughly mixed.

[0034] The substrate was heated at 175°C and sheared at a speed of 250 sec. -1 The melt viscosity during the reaction can be controlled by, for example, adjusting the content of the plasticizer contained in the resin composition. Alternatively, the flow rate of the substrate can be measured at 175°C and a shear rate of 250 / sec using a capillary die of L = 40 mm and D = 1 mm and a capillary rheometer 1D manufactured by Toyo Seiki Seisaku-sho Co., Ltd. as a measuring device. -1 The melt viscosity at .

[0035] <Melt tension of substrate> The melt tension of the substrate according to one embodiment of the present invention at 175°C and a pulling speed of 1.0 m / min is 0.01 to 0.10 N, preferably 0.02 to 0.09 N, and more preferably 0.03 to 0.08 N. Specifically, for example, it is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.10 N, and may be within a range between any two of the values ​​exemplified herein. By setting the melt tension to 0.01 N or higher, the substrate can be stretched during the film-forming step of substrate production, thereby preventing excessive stretching that could result in holes or breakage. Furthermore, by setting the melt tension to 0.10 N or lower, the substrate can be stretched sufficiently during the film-forming step of substrate production, making it easier to control the MD stretch ratio.

[0036] The melt tension of the substrate at 175° C. and a pulling speed of 1.0 m / min can be controlled by, for example, adjusting the content of the plasticizer contained in the resin composition. Alternatively, the melt tension of the substrate at 175°C and a take-up speed of 1.0 m / min can be measured by using a capillary die with a length of 40 mm and a diameter of 1 mm under a shear rate of 120 / sec. The resin extruded from the capillary die is wound at a rate of 1 m / min. This measurement can be performed using a capillary rheometer 1D manufactured by Toyo Seiki Seisaku-sho, Ltd.

[0037] <Storage elastic modulus of substrate> The storage elastic modulus of the substrate according to one embodiment of the present invention, when subjected to dynamic viscoelasticity measurement in shear mode at a temperature of 175°C and an angular frequency of 0.1 rad / s, is preferably 20.0 to 70.0 kPa, more preferably 30.0 to 65.0 kPa, and even more preferably 50.0 to 60.0 kPa. Specifically, for example, it is preferably 20.0, 30.0, 40.0, 50.0, 60.0, 65.5, or 70.0 kPa, and may be within a range between any two of the values ​​exemplified herein. A storage modulus of 20.0 kPa or higher facilitates substrate peeling from a roll during film formation, enabling stable film formation. Furthermore, a storage modulus of 70.0 kPa or lower facilitates thickness adjustment during film formation, making it easier to achieve a desired film thickness.

[0038] The storage elastic modulus of the substrate when subjected to dynamic viscoelasticity measurement in a shear mode at a temperature of 175° C. and an angular frequency of 0.1 rad / s can be controlled by, for example, adjusting the content of the plasticizer contained in the resin composition. Alternatively, multiple sheets of substrates may be stacked and pressed at 150°C and 10 MPa for 1 minute using a tabletop vacuum testing press SA-303 manufactured by TESTER SANGYO. For the resulting disc-shaped sample having a thickness of 1 mm and a diameter of 25 mm, a rheometer MCR302 (parallel plate φ25 mm) manufactured by Anton Paar may be used to measure the storage elastic modulus of the substrate when subjected to dynamic viscoelasticity measurement in shear mode at a temperature of 175°C and an angular frequency of 0.1 rad / s.

[0039] <Tensile elastic modulus of substrate> The tensile strength of the substrate according to one embodiment of the present invention is measured according to the conditions of "Item 8, 'Tensile Strength and Elongation at Break'" of JIS C 2107. The tensile modulus is calculated from the results using the formula: "Tensile modulus (MPa) = [Tensile stress (MPa) measured at a strain of 0.02 - Tensile stress (MPa) measured at a strain of 0.015] / 0.005." The calculated tensile modulus is preferably 2 to 3,500 MPa, more preferably 20 to 2,000 MPa, and even more preferably 80 to 1,500 MPa or higher. Specifically, for example, the tensile modulus is preferably 2, 10, 50, 100, 200, 500, 1,000, 1,500, 2,000, 2,500, 3,000, or 3,500 MPa, and may be within a range between any two of the values ​​exemplified here. A tensile modulus of 2 MPa or greater allows for a substrate with a hardness suitable for handling as an adhesive tape, which is advantageous from the perspective of work efficiency. Furthermore, a tensile modulus of 3,500 MPa or less allows for a substrate with a flexibility suitable for handling as an adhesive tape, which is advantageous from the perspective of work efficiency.

[0040] The tensile modulus of the substrate can be controlled by, for example, adjusting the content of the plasticizer contained in the resin composition.

[0041] <Thickness of base material> The thickness of the substrate in one embodiment of the present invention is 25 to 65 μm, preferably 40 to 60 μm, and more preferably 45 to 55 μm. Specifically, for example, it is 25, 30, 35, 40, 45, 50, 55, 60, or 65 μm, and may be within a range between any two of the values ​​exemplified here. By setting the substrate thickness to 65 μm or less, the substrate becomes thinner, thereby achieving a thinner and lighter adhesive tape. Furthermore, by setting the substrate thickness to 25 μm or greater, the required strength of the adhesive tape can be maintained. Furthermore, by using a substrate that meets the above requirements, the adhesive tape of the present invention can maintain the required substrate strength even when the thickness is 65 μm or less.

[0042] The thickness of the substrate can be controlled by, for example, adjusting the gap between the calender rolls of a calender film forming machine or applying stretching. Alternatively, the thickness of the substrate can be measured using a thickness meter (manufactured by Mitutoyo Co., Ltd.) after removing only the adhesive layer of the adhesive tape with a solvent.

[0043] <Adhesive layer> The adhesive layer according to one embodiment of the present invention includes an adhesive. The adhesive may contain, for example, a base polymer, a tackifier, and other additives.

[0044] Adhesives The adhesive layer of one embodiment of the present invention is preferably a rubber-based adhesive, which may be either a solvent-based or emulsion-based adhesive. From the perspective of exhibiting adhesive strength to all adherends, the rubber-based adhesive preferably contains a rubber component as a base polymer and a tackifier.

[0045] <Base polymer> Examples of the rubber component as a base polymer include natural rubber, styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), hydrogenated products of the above-mentioned styrene-based block copolymers (SIPS, SEBS), styrene-butadiene rubber (SBR), polyisoprene rubber (IR), polyisobutylene (PIB), and synthetic rubbers such as butyl rubber (IIR), and graft copolymers of (meth)acrylic acid alkyl esters and at least one rubber component selected from natural rubber and the above-mentioned synthetic rubbers. From the perspective of improving the self-back adhesive force caused by the increase in the elastic modulus of the adhesive layer or suppressing the cohesive failure of the adhesive layer, in this embodiment, the rubber-based adhesive preferably includes a graft copolymer of (meth)acrylic acid alkyl esters and at least one rubber component selected from natural rubber and synthetic rubber (hereinafter sometimes also described as "graft rubber"). These can be selectively used alone or in combination of two or more.

[0046] The tackifier can be selected based on its softening point and compatibility with the other components. Examples include emulsions of terpene resins, rosin resins, hydrogenated rosin resins, coumarone-indene resins, styrene resins, petroleum resins, terpene-phenol resins, xylene resins, and other aliphatic or aromatic hydrocarbon resins. Petroleum resins are preferred for their ability to impart good viscosity. These may be used alone or as a mixture of two or more.

[0047] <Thickness of adhesive layer> The thickness of the adhesive layer in one embodiment of the present invention is 0.5 to 12.0 μm, preferably 2.0 to 10.0 μm, specifically, 0.5, 1.0, 1.5, 2.0, 3.0, 5.0, 8.0, 10.0, 11.0, or 12.0 μm, or may be within a range between any two of the values ​​exemplified here. By setting the thickness of the adhesive layer to 12.0 μm or less, the adhesive layer becomes thinner, thereby achieving a thinner and lighter adhesive tape. Furthermore, by setting the thickness of the adhesive layer to 0.5 μm or greater, the required adhesive strength of the adhesive tape can be maintained. Furthermore, by using an adhesive layer that meets the above requirements, the adhesive tape of the present invention can maintain the required adhesive strength even when the thickness is 12.0 μm or less.

[0048] The thickness of the adhesive layer can be controlled, for example, by film coating using a gravure roll, or by narrowing the gap or adjusting the solid content concentration of the adhesive when gap coating is performed. Alternatively, the thickness of the adhesive layer can be measured by measuring the tape thickness according to the conditions of "Item 5 'Measurement of Thickness'" of JIS C 2107, then removing only the adhesive layer of the adhesive tape with a solvent, and measuring the substrate thickness using a thickness gauge (manufactured by Mitutoyo Co., Ltd.) to determine the difference between the tape thickness and the substrate thickness.

[0049] <Method for producing adhesive tape> <Manufacturing of base materials> For the manufacture of the resin combination of the base material of the present embodiment, thermoplastic resin and necessary plasticizer, filler, heat stabilizer, light absorber, pigment, other additives etc. can be melt-mixed and obtained.The melt-mixing method is not particularly limited, and various mixers and mixing machines, such as twin-shaft extruder, continuous and batch kneader, roller, Banbury mixer etc. can be used to possess heating device, mix the above-mentioned resin combination in a uniformly dispersed manner.By calendering method, T-die method, inflation method etc. as customary forming method, the mixture of gained is shaped into base material.With regard to aspects such as productivity, discoloration, shape uniformity, forming machine is preferably calendering forming machine.The roller arrangement mode in calendering forming, for example, can adopt the known modes such as L-type, inverted L-type, Z-type.

[0050] <Base material molding> <Temperature of the resin composition immediately before stretching> When the substrate of this embodiment is formed, the temperature of the resin composition immediately before the film is stretched is preferably 165°C or higher, more preferably 170°C or higher, and even more preferably 175°C or higher. The upper limit of the temperature of the resin composition immediately before stretching is not particularly limited, but from the perspective of preventing resin decomposition, it is practical to set it to 190°C or lower. By setting the temperature of the resin composition immediately before stretching to above 165°C, the resin can be fully mixed within the step, making it easy to control the thickness. In addition, it is easy to control the TD shrinkage rate or MD shrinkage rate of the resulting substrate under heating conditions of 110°C for 5 minutes within the desired range. The temperature of the resin composition immediately before stretching refers to the temperature of the resin composition immediately after film formation and before stretching. For example, in the case of a calendering machine, this temperature refers to the temperature at which the film-formed resin composition begins stretching while being peeled off from the calendering rolls by a take-off roll (draw roll) after film formation using the calendering rolls. This temperature can be controlled by adjusting the set temperature of the calendering rolls.

[0051] <MD stretch ratio> When the substrate of this embodiment is formed using a calendaring machine, the MD stretch ratio when stretching the resin composition to form a film is preferably 3.5 times or less, more preferably 3.0 times or less, and even more preferably 2.0 times or less. The lower limit of the stretch ratio is not particularly limited, but from the perspective of the operating efficiency of the drawing step, it is more practical to set it to 1.1 times or more. By setting the stretching ratio to 3.5 times or less, it is easy to control the TD shrinkage rate or MD shrinkage rate of the obtained substrate under heating conditions of 110° C. for 5 minutes within a desired range. The MD stretch ratio during stretching in the present invention refers to the sum of the stretch ratio when drawing from the calender roll to the take-off roll and the stretch ratio when drawing from the take-off roll to the take-up roll. Furthermore, the MD stretch ratio can be controlled by adjusting the speed of the calendering roll and the speed of the take-off roll immediately following the calendering roll.

[0052] <Provision of Adhesive Layer> The adhesive tape of this embodiment is obtained by, for example, applying an adhesive to at least one side of the substrate obtained in the above manner, thoroughly removing the solvent in a drying oven, and then applying the adhesive. Examples of adhesive application methods include lip die, gravure, roller, and slot die.

[0053] <Primer layer> The pressure-sensitive adhesive tape of the present embodiment may optionally include a primer layer between the substrate and the pressure-sensitive adhesive layer for the purpose of improving the adhesion between the substrate and the pressure-sensitive adhesive layer within a range that does not impair the effects of the present invention. The primer for forming the primer layer preferably contains 25 to 300 parts by mass of an acrylonitrile-butadiene copolymer based on 100 parts by mass of a graft polymer obtained by graft-polymerizing methyl methacrylate and natural rubber.

[0054] <Applications of Adhesive Tape> The adhesive tape of this embodiment is suitably used as an adhesive tape for bundling electric wires such as high-voltage cables and wire harnesses in electric vehicles and hybrid vehicles, for example. The electric wires bundled with the adhesive tape of this embodiment are lightweight, and thus the bundled electric wires are also lightweight. [Example]

[0055] Hereinafter, the present invention will be described in more detail with reference to the following examples, which are merely illustrative and do not limit the present invention.

[0056] <Making the base material> Materials used (1) Thermoplastic resin Polyvinyl chloride resin, average degree of polymerization 650-770: Product name "TH-700", manufactured by Taiyo Vinyl Co., Ltd. Polyvinyl chloride resin, average degree of polymerization 980-1,080: Product name "TH-1000", manufactured by Taiyo Vinyl Co., Ltd. Polyvinyl chloride resin, average degree of polymerization 1,270 to 1,370: Product name "TH-1300," manufactured by Taiyo Vinyl Co., Ltd. Polyvinyl chloride resin, average degree of polymerization 1,600-1,800: Product name "TH-1700", manufactured by Taiyo Vinyl Co., Ltd. (2) Plasticizer Phthalate plasticizer, diisononyl phthalate: Product name "DINP," manufactured by J-Plus Co., Ltd. Trimellitic acid ester plasticizer, trioctyl trimellitate: Product name "Monocizer W-750", manufactured by DIC Corporation Adipate-based plasticizer, adipic acid polyester, weight-average molecular weight 2,300, product name "Polycizer W-2050," manufactured by DIC Corporation (3) Fillers Calcium carbonate: average particle size 0.18 μm, product name "Calseeds (registered trademark) P", manufactured by Shinjima Chemical Industry Co., Ltd.

[0057] Thermoplastic resin, plasticizer, filler, and other additives were melt-kneaded in a uniformly dispersed manner using a Banbury mixer according to the compositions shown in Tables 1 and 2. The substrates were then produced into substrates of a specified thickness using a calendaring machine at the roll temperature and stretch ratio (overall stretch ratio) shown in Tables 1 and 2.

[0058] <Adhesive Tape Production> Materials used (1) Base material The substrate prepared through the above steps (2) Primer A mixture of a graft polymer latex obtained by graft polymerization of methyl methacrylate and natural rubber and an acrylonitrile-butadiene copolymer emulsion. Product name: KT4612A, manufactured by E-TEC Co., Ltd. (3) Adhesive layer [Base polymer] Natural rubber latex: Product name "HA LATEX", manufactured by REGITEX Co., Ltd. Graft polymer latex obtained by grafting methyl methacrylate onto natural rubber: Product name "MG-40S", manufactured by REGITEX Co., Ltd. Styrene-butadiene rubber latex: Product name "T-093A", manufactured by JSR Co., Ltd. In the table, NR refers to natural rubber, MMA refers to methyl methacrylate, and SBR refers to styrene-butadiene rubber. [Thickener] Petroleum resin emulsion: Product name "AP-1100", manufactured by Arakawa Chemical Industries, Ltd. Terpene-phenol resin emulsion: Product name "E200", manufactured by Arakawa Chemical Industries, Ltd. [additive] Surfactant: Product name "OT-P", manufactured by Kao Corporation Antioxidant / Plasticizer: Product name "DIEM", manufactured by SAN-AIOBBLI Co., Ltd.

[0059] A primer was applied to one side of the substrate using a gravure coating method. After the solvent was thoroughly removed in a drying oven, an adhesive was applied using a roller method. The solvent was then thoroughly removed in a drying oven, similar to the primer, to produce an adhesive tape. The dried thickness of the primer layer was 0.3 μm, and the dried thickness of the adhesive layer was 7 μm.

[0060] <Physical Properties of Base Material and Adhesive Tape> The physical properties of the substrate and the pressure-sensitive adhesive tape were measured and evaluated under the following measurement conditions. The results are shown in Tables 1 and 2.

[0061] Melt viscosity The melt viscosity was measured at 175° C. and a shear rate of 250 / sec using a capillary die having a diameter of 40 mm and a diameter of 1 mm. The measuring apparatus used was a capillary rheometer 1D manufactured by Toyo Seiki Seisaku-sho Co., Ltd.

[0062] Melt tension Melt tension was measured at 175°C and a shear rate of 120 / sec using a capillary die with a diameter of 40 mm (L) and a diameter of 1 mm. The resin extruded from the capillary die was pulled at a speed of 1 m / min. The measurement apparatus used was a Capillary Rheometer 1D manufactured by Toyo Seiki Seisaku-sho, Ltd.

[0063] <Heating shrinkage of MD> After a 50 mm square film was heat-treated at 110° C. for 5 minutes, the side length in MD was measured, and the heat shrinkage in MD was calculated by the following formula. MD heating shrinkage (%) = [50 - MD side length after heating (mm)] / 50 × 100

[0064] <Heating shrinkage of TD> After a 50 mm square film was heat-treated at 110° C. for 5 minutes, the side length in TD was measured, and the heat shrinkage in TD was calculated by the following formula. TD heating shrinkage (%) = [50 - TD side length after heating (mm)] / 50 × 100

[0065] Storage elastic modulus Multiple sheet-like substrates were overlapped and pressed at 150°C and 10 MPa for 1 minute using a tabletop vacuum test press SA-303 manufactured by TESTER SANGYO to obtain a sheet with a thickness of 1 mm. The obtained sheet was cut into a φ25 mm disc to obtain a sample. The obtained sample was subjected to dynamic viscoelasticity measurement in shear mode using a rheometer MCR302 (parallel plate φ25 mm) manufactured by Anton Paar. After the sample was installed in the above-mentioned device, it was measured at a temperature of 175°C in the range of angular frequency of 0.1 to 100 rad / s to obtain the measured value of the storage elastic modulus (G') GPa.

[0066] <Tensile elastic modulus> The tensile strength of the substrate was measured according to the conditions of "Item 8 'Tensile strength and elongation at break'" of JIS C 2107. The tensile modulus was calculated from the measurement results using the following formula. Tensile modulus (MPa) = [tensile stress measured at a strain of 0.02 (MPa) - tensile stress measured at a strain of 0.015 (MPa)] / 0.005

[0067] Adhesion Adhesion was evaluated according to the following procedure. Adhesion (normal, back of body) The adhesive strength of the adhesive tape was measured according to the conditions of "Item 11 'Adhesive strength'" of JIS C 2107.

[0068] <Base material strength> The substrate strength was evaluated from the perspectives of stress at break and elongation at break. Elongation at break is a physical property that includes flexibility, an important characteristic for use as an adhesive tape. (Breaking point stress) The strength of the substrate was evaluated based on the stress at break using the following procedure. The tensile strength of the substrate was measured according to the conditions of "Item 8 'Tensile strength and elongation at break'" of JIS C 2107. (Elongation at break) The strength of the substrate was evaluated based on the elongation at break using the following procedure. The elongation at break of the substrate was measured in accordance with the conditions of "Item 8 'Tensile strength and elongation at break'" of JIS C 2107.

[0069] <Film Stability> The stability of the film formation and the resulting substrate state were evaluated according to the following procedure. During substrate production, visually inspect the substrate for cracks. Additionally, visually inspect the substrate for pinholes within a 1-meter square on the film produced by the calendering machine. If pinholes were found, their maximum diameter was measured using a microscope. Furthermore, the thickness of the film-forming substrate was measured at 10 random locations using a thickness gauge (manufactured by Mitutoyo Co., Ltd.). According to the following criteria, an evaluation of C or higher is considered acceptable. A: The substrate was not broken when the film was produced by the calendaring machine, no pinholes were confirmed on the film-forming substrate, and the substrate thickness was within ±10% of the specified thickness. B: Any of the following conditions (1) and (2) occurs. (1) The substrate did not break when the film was produced by the calendaring machine, and the measured substrate thickness was within ±10% of the specified thickness. However, tiny pinholes with a diameter of less than 1 mm were confirmed on the film-forming substrate. (2) The substrate does not break when the film is formed by the calendaring machine, and no pinholes are confirmed on the film-forming substrate. However, the measured substrate thickness exceeds the specified thickness by ±10% at one or more points and is within ±15%. C: The substrate does not break when formed by calendaring, but tiny pinholes with a diameter of less than 1 mm are observed in the film-forming substrate, and the measured substrate thickness exceeds the specified thickness by ±10% at one or more points and is within ±15%. D: Any of the following conditions (1) to (3) occurs. (1) The substrate breaks when the film is made by calendaring (2) Pinholes with a diameter of 1 mm or more are confirmed on the film substrate (3) The measured thickness of the substrate exceeds the specified thickness by ±15% at one or more points

[0070] <Coating stability> The coating stability and the resulting substrate condition were evaluated according to the following procedure. When producing the adhesive tape, a predetermined adhesive coating liquid is applied to a substrate, the adhesive coating liquid is dried in a drying oven, and the substrate surface at this time is observed. Regarding the condition of the substrate surface, a condition evaluated as B or higher according to the following criteria was considered acceptable. A: No wrinkles are generated on the substrate surface due to drying heat B: Wrinkles were generated due to the heat of drying, but they disappeared when the paper was rolled onto a paper tube. C: Wrinkles are generated on the substrate surface due to the heat of drying. When the substrate is rolled onto the paper tube, the wrinkles remain and are not eliminated.

[0071] <Wire Winding Properties> The wire winding properties were evaluated according to the following procedure. Prepare 10 heat-resistant electric wires for automobiles cut to a length of 800 mm (manufactured by Sumitomo Electric Industries, Ltd., product name "AVX050", diameter: 50 mm) and 4 heat-resistant electric wires for automobiles cut to a length of 800 mm (manufactured by Sumitomo Electric Industries, Ltd., product name "AVX085", diameter: 85 mm). Bundle these 14 electric wires and fix both ends in the length direction with adhesive tape to facilitate the winding operation. Then, the adhesive tape (width 19 mm) of each example is wound around the periphery of the above-mentioned electric wires in a half-overlapping manner to prepare evaluation samples. Here, "half-overlapping" means that when the adhesive tape is wound around the electric wire, it is wound in a manner that half of the width of the adhesive tape overlaps half of the width of the already wound adhesive tape. For the samples produced, the end peeling of the adhesive tape is evaluated according to the following evaluation criteria, and an evaluation of B or above is considered qualified. A: No end peeling was observed. B: Slight end peeling was observed (end peeling distance was less than 1.0 mm). C: End peeling was observed (end peeling distance was 1.0 mm or more).

[0072] [Table 1]

[0073] [Table 2]

[0074] The results in Tables 1 and 2 show that the adhesive tapes of the Examples achieve excellent lightweight properties through thinning, possess substrate strength and adhesive strength suitable for bundling cables and other electrical wires, and exhibit excellent film formation and coating stability during production, as well as excellent substrate condition. On the other hand, the adhesive tapes of the Comparative Examples, while successfully achieving lightweight properties through thinning, are inferior in terms of one or more of substrate strength suitable for bundling cables and other electrical wires, film formation stability related to substrate condition, and coating stability. [Industrial Applicability]

[0075] The adhesive tape of the present invention is lightweight, exhibits good substrate strength and adhesion, and maintains excellent substrate condition. The adhesive tape of the present invention is suitable for bundling and protecting electrical wires, such as high-voltage cables in electric and hybrid vehicles and wiring harnesses in automobiles, and thus has industrial applicability.

Claims

1. An adhesive tape comprising: A substrate composed of a resin composition containing a thermoplastic resin, and an adhesive layer provided on at least one side of the substrate, The TD shrinkage of the substrate under heating conditions of 110° C. for 5 minutes is -5.0% to 0%. The MD shrinkage of the substrate under heating conditions of 110° C. for 5 minutes is 0-15%. The thickness of the substrate is 25 to 65 μm, The thickness of the adhesive layer is 0.5 to 12.0 μm. The substrate was heated at 175°C and a shear rate of 250 sec -1 The melt viscosity is 300 to 1,300 Pa·s. The melt tension of the substrate at 175° C. and a pulling speed of 1.0 m / min is 0.01 to 0.10 N.

2. The adhesive tape according to claim 1, wherein The storage elastic modulus of the substrate when subjected to dynamic viscoelasticity measurement in a shear mode at a temperature of 175° C. and an angular frequency of 0.1 rad / s is 20.0 to 70.0 kPa.

3. The adhesive tape according to claim 1 or 2, wherein The tensile strength of the substrate was measured according to the conditions of "Item 8 'Tensile strength and elongation at break'" of JIS C 2107. The tensile modulus was calculated from the obtained results using the following formula to obtain a tensile modulus of 2 to 3500 MPa: Tensile elastic modulus (MPa) = [tensile stress (MPa) measured at a strain of 0.02 - tensile stress (MPa) measured at a strain of 0.015] / 0.

005.

4. The adhesive tape according to claim 1 or 2, wherein The thermoplastic resin is a polyvinyl chloride resin, and the average polymerization degree of the polyvinyl chloride resin is 500 to 2,000.

5. The adhesive tape according to claim 1 or 2, wherein The resin composition contains 20 to 75 parts by mass of a plasticizer and 30 parts by mass or less of a filler based on 100 parts by mass of the thermoplastic resin. The adhesive tape according to claim 5 , wherein The average particle size of the filler is 0.3 μm or less.

7. The adhesive tape according to claim 5, wherein The plasticizer includes at least one selected from trimellitic acid ester plasticizers, phthalic acid ester plasticizers, and adipate plasticizers.

8. The adhesive tape according to claim 1 or 2, wherein The adhesive layer includes a tackifier.

9. The adhesive tape according to claim 8, wherein The tackifier includes petroleum resin.

10. The adhesive tape according to claim 1 or 2, wherein The adhesive layer includes a graft copolymer of an alkyl (meth)acrylate and at least one rubber component selected from natural rubber and synthetic rubber.

11. The adhesive tape according to claim 1 or 2, wherein The thickness of the substrate is 40 to 60 μm.

12. The adhesive tape according to claim 1 or 2, wherein The thickness of the adhesive layer is 2.0 to 10.0 μm. 13 . The adhesive tape according to claim 1 , which is used for bundling electric wires.

14. Electric wires bundled with the adhesive tape according to claim 13.

15. A method for producing the adhesive tape according to claim 1 or 2, comprising the following steps: stretching a resin composition comprising the thermoplastic resin in a MD at a stretching ratio of 3.5 times or less to obtain a substrate; as well as Disposing the adhesive layer on at least one side of the substrate; In the step of obtaining the substrate, the temperature of the resin composition immediately before stretching is 165° C. or higher.

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