Adhesive tape

Abstract

To provide an adhesive tape showing tack sufficient for quick fixation of an article during application and adhesive strength sufficient for reliable retention of the article, with reduced tendency to leave adhesive residue on the adherend at the time of peeling.SOLUTION: An adhesive tape comprises a base material and an adhesive layer formed on the base material, the adhesive layer containing natural rubber, a crosslinking agent, a tackifying resin, and a softener, the storage modulus G' at 150°C measured at a frequency of 1 Hz being in the range of 17,000 Pa or more and 55,000 Pa or less, the crosslinking agent containing sulfur or a sulfur donor, the adhesive tape having a 180° peel adhesion to a SUS plate of 0.9 N / 10 mm or more and a tack of 17 or more at an inclination angle of 30°.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an adhesive tape, and more particularly to an adhesive tape used for temporarily fixing an article containing a plasticizer.

Background Art

[0002] At facilities temporarily used such as video production sites, concert halls, theaters, and disaster shelters, equipment is installed as needed. To maintain the functions of the equipment and ensure the safety of users, various devices and power / information communication cables are fixed in predetermined positions. In this case, for the purpose of reducing the work burden, securely fixing in a short time, an adhesive tape is used to adhere the devices and power / information communication cables to the floor or the like. After the use of the facility is completed, the equipment is disassembled and the adhesive tape is peeled off from the devices, power / communication cables, floor, etc. As the above adhesive tape, for example, an adhesive tape having a rubber-based adhesive layer on a cloth substrate is preferably used.

[0003] Generally, power / information communication cables are coated with polyvinyl chloride resin. Polyvinyl chloride resin contains plasticizers such as phthalic acid esters such as di(2-ethylhexyl) phthalate, dibutyl phthalate, butyl benzyl phthalate, diisobutyl phthalate, diisononyl phthalate, and adipic acid esters such as dibutyl adipate. When an adhesive tape is adhered to the surface of a resin containing a plasticizer, the plasticizer migrates into the adhesive layer of the adhesive tape, and the mobility of the polymer molecular chains in the adhesive layer is promoted by the solvation and lubricating action of the plasticizer. As a result, there are problems such as a decrease in the cohesive force of the adhesive layer, a part of the adhesive layer remaining on the surface of the resin when the adhesive tape is peeled off, and contamination of the surface of the resin.

[0004] Patent Document 1 describes an acrylic pressure-sensitive adhesive tape in which a multi-layer adhesive layer is formed, and the exposed adhesive layer is mainly composed of an adhesive comprising an acrylic copolymer obtained by copolymerizing a nitrogen-containing basic acrylic monomer with an alkyl (meth)acrylate monomer at a specific ratio. The acrylic pressure-sensitive adhesive tape of Patent Document 1 exhibits sufficient values for both initial adhesive strength and cohesive strength, and is said to show excellent adhesive performance in which both are harmonized and there is no transfer of plasticizers or the like to the plasticized vinyl chloride resin.

[0005] Patent Document 2 describes a pressure-sensitive adhesive composition for masking tape obtained by adding a tackifier resin, a thiuram compound, etc. to a base polymer containing natural rubber, styrene-butadiene copolymer rubber, and polyisobutylene. When performing spot painting on automobile bumpers, outer panels, etc., various masking tapes are used. Masking tapes are required to have performance such as adhesiveness, heat resistance, no adhesive remaining on the tape peeling surface, and a clear cut-off line for the coating film in the masked area. The pressure-sensitive adhesive composition for masking tape of Patent Document 2 is said to be excellent in the cut-off property of painting masking and to be able to provide a masking tape without residue (sticking marks) of the pressure-sensitive adhesive.

[0006] Patent Document 3 describes an adhesive composition containing natural rubber, a crosslinking agent, a tackifier resin, and a crosslinking regulator. The minimum temperature of the loss tangent after curing of the adhesive composition is 78.7 °C or higher and the minimum value is 0.20 or lower, and the maximum temperature of the loss tangent is 25.0 °C or lower and the maximum value is 1.15 or lower. The adhesive composition of Patent Document 3 uses a rubber-based adhesive, and even when exposed to high temperature or high temperature and high humidity environments during the manufacturing, assembly, and transportation stages of articles, there is little contamination of the adherend after re-peeling, and it has excellent adhesive strength, so it can provide a temporary fixing adhesive tape that can sufficiently temporarily fix articles even with a narrow width.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] Conventional adhesive tapes still have room for improvement in achieving, at the same time, tack for quickly fixing an article during sticking, adhesive force for securely fixing the article, and a performance of being difficult to leave glue on the adherend during peeling. In particular, when an adhesive tape is stuck to the surface of a resin containing a plasticizer, there is still a problem that a part of the adhesive layer remains on the surface of the resin during peeling.

Means for Solving the Problems

[0009] The present invention provides the following aspects. A first form of the adhesive tape of the present invention is an adhesive tape having a base material and an adhesive layer formed on the base material, wherein the adhesive layer contains natural rubber, a crosslinking agent, an adhesion-imparting resin, and a softening agent, and has a storage elastic modulus G' at 150 °C measured at a frequency of 1 Hz of 17,000 Pa or more and 55,000 Pa or less, preferably 20,000 Pa or more and 52,000 Pa or less, more preferably 23,000 Pa or more and 42,000 Pa or less, still more preferably 27,000 Pa or more and 40,000 Pa or less, the crosslinking agent is a crosslinking agent containing sulfur or a sulfur donor, and the adhesive tape has a 180° peel adhesive force to a SUS plate of 0.9 N / 10 mm or more, preferably 1.3 N / 10 mm or more and 7.7 N / 10 mm or less, more preferably 1.7 N / 10 mm or more and 6.0 N / 10 mm or less, still more preferably 2.9 N / 10 mm or more and 4.0 N / 10 mm or less, and a tack at an inclination angle of 30 degrees of 17 or more, preferably 18 or more and 24 or less, more preferably 20 or more and 23 or less.

[0010] The second form of the pressure-sensitive adhesive tape of the present invention is the pressure-sensitive adhesive tape of the first form, wherein the crosslinking agent is contained in an amount of 0.85 parts by mass or more and 2.8 parts by mass or less, preferably 1.4 parts by mass or more and 2.7 parts by mass or less, and more preferably 1.6 parts by mass or more and 2.2 parts by mass or less with respect to 100 parts by mass of natural rubber.

[0011] The third form of the pressure-sensitive adhesive tape of the present invention is the pressure-sensitive adhesive tape of the first or second form, wherein the tackifier resin is contained in an amount of 80 parts by mass or more and 175 parts by mass or less, preferably 100 parts by mass or more and 150 parts by mass or less, and more preferably 105 parts by mass or more and 130 parts by mass or less with respect to 100 parts by mass of natural rubber.

[0012] The fourth form of the pressure-sensitive adhesive tape of the present invention is the pressure-sensitive adhesive tape of any one of the first to third forms, wherein the tackifier resin has a softening point of 110°C or higher and 140°C or lower and a solubility parameter (SP value) of 7.5 or higher and 8.4 or lower.

[0013] The fifth form of the pressure-sensitive adhesive tape of the present invention is the pressure-sensitive adhesive tape of any one of the first to fourth forms, wherein the softening agent is contained in an amount of 36 parts by mass or more and 44 parts by mass or less, preferably 37 parts by mass or more and 43 parts by mass or less, and more preferably 38 parts by mass or more and 42 parts by mass or less with respect to 100 parts by mass of natural rubber.

[0014] The sixth form of the pressure-sensitive adhesive tape of the present invention is the pressure-sensitive adhesive tape of any one of the first to fifth forms, wherein the sulfur donor is a thiuram compound.

Advantages of the Invention

[0015] According to the present invention, it is possible to simultaneously satisfy tack for quickly fixing an article during attachment, adhesive force for securely fixing the article, and performance of being difficult to leave adhesive residue on an adherend during peeling. In particular, when an adhesive tape is attached to the surface of a resin containing a plasticizer, it is possible to provide an adhesive tape in which a part of the adhesive layer is difficult to remain on the surface of the resin during peeling.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0017] Hereinafter, an embodiment of the present invention will be described in detail. However, the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Also, when a plurality of upper limit values and lower limit values are described for specific parameters, any upper limit value and lower limit value can be combined to form a suitable numerical range.

[0018] The adhesive tape of the present invention is an adhesive tape having a sheet-like base material and an adhesive layer formed on one or both sides of the base material. For example, referring to FIG. 1, a single-sided adhesive tape in which an adhesive layer 12 is formed on one side of a base material 11 corresponds to the adhesive tape of the present invention. Also, referring to FIG. 2, a double-sided tape in which an adhesive layer 22 and an adhesive layer 23 are formed on both sides of a base material 21 corresponds to the adhesive tape of the present invention.

[0019] <Adhesive Force> The adhesive tape of the present invention exhibits an adhesive force of 0.9 N / 10 mm or more as the 180° peel adhesive force (against SUS). The 180° peel adhesive force (against SUS) is determined by adhering, pressing, and curing the adhesive tape of the present invention to a BASUS plate, which is the adherend (test plate), in accordance with JIS Z 0237, using the resulting product as a test sample, continuously peeling it at a speed of 300 mm / min with a tensile testing machine at 180°, and measuring the load during peeling. The measurement conditions shown in the examples can be used. The BASUS plate refers to a SUS plate finished by bright annealing (bright annealing).

[0020] If the 180° peel adhesive force of the adhesive tape is less than 0.9 N / 10 mm, the adhesive force for fixing the article during sticking becomes insufficient. The 180° peel adhesive force of the adhesive tape is preferably 1.3 N / 10 mm, more preferably 1.7 N / 10 mm, and still more preferably 2.9 N / 10 mm as its lower limit value. Also, the above 180° peel adhesive force is preferably 7.7 N / 10 mm, more preferably 6.0 N / 10 mm, and still more preferably 4.0 N / 10 mm as its upper limit value. If the above 180° peel adhesive force exceeds 7.7 N / 10 mm, the re-peelability of the adhesive tape may deteriorate. More specifically, the above 180° peel adhesive force is preferably in the range of 1.3 N / 10 mm or more and 7.7 N / 10 mm or less, more preferably 1.7 N / 10 mm or more and 6.0 N / 10 mm or less, and still more preferably 2.9 N / 10 mm or more and 4.0 N / 10 mm or less. When the 180° peel adhesive force of the adhesive tape is within the above range, for example, articles such as the above-described cable can be firmly temporarily fixed to the floor surface, while being able to be re-peeled well without leaving paste on the adhesive tape.

[0021] <Tack> The adhesive tape of the present invention exhibits a value of 17 or more as the tack measured at an inclination angle of 30 degrees. The tack is measured in accordance with JIS Z 0237, using an inclined ball tack device, fixing and setting the adhesive tape with the adhesive surface facing up at a predetermined position on the inclined plate, and measuring with an inclination angle of 30 degrees.

[0022] If the tack of the adhesive tape is less than 17, the wettability to the adherend deteriorates. Therefore, when temporarily fixing an article during pasting, it cannot be firmly adhered without applying pressure or time, resulting in poor workability. As the lower limit value of the above tack, it is preferably 18, more preferably 20. Also, as the upper limit value of the above tack, it is preferably 24, more preferably 23. When the above tack exceeds 24, when the plasticizer of the article migrates to the adhesive layer, a certain cohesive force required for the adhesive layer cannot be maintained, and there is a risk of glue residue remaining on the article surface during peeling. More specifically, the above tack is preferably in the range of 18 or more and 24 or less, more preferably 20 or more and 23 or less. When the above tack is within the above range, for example, an article such as the cable described above can be quickly and temporarily fixed to the floor surface in a short time, while the adhesive tape can be well re-peeled without leaving glue residue.

[0023] <Storage elastic modulus G'> As a result of the inventors' study, it has been clarified that the elasticity of the adhesive layer at high temperature is related to the re-peeling performance of the adhesive tape after temporarily fixing an article containing a plasticizer. The adhesive layer is a member that transmits the peeling force applied to the adhesive tape during peeling to the adhesion surface. In the adhesive tape of the present invention, by adjusting the storage elastic modulus G' of the adhesive layer at high temperature, the balance among the initial cohesive force, adhesive force (adhesion), and tack of the adhesive layer is optimized, and even when a plasticizer migrates from the article to the adhesive layer between temporarily fixing and re-peeling the article, the degree of decrease in the cohesive force of the entire adhesive layer is significantly suppressed, and a certain cohesive force can be maintained without glue residue occurring on the article (adherend) during re-peeling. Thereby, the adhesive tape has a tack and adhesive force capable of surely temporarily fixing an article containing a plasticizer in a short time, while being difficult to leave glue residue on the article (adherend) during re-peeling.

[0024] Regarding the above findings, details are described below. First, the main problem of the present invention is how to reduce the influence of the plasticizer on the network structure of the polymer in the pressure-sensitive adhesive layer, such as solvation and lubrication, and suppress the degree of decrease in the cohesive force of the entire pressure-sensitive adhesive layer when the plasticizer migrates from the article to the pressure-sensitive adhesive layer after temporarily fixing the article containing the plasticizer with a pressure-sensitive adhesive tape and then re-peeling it. As a measure to suppress the influence of the above plasticizer, a method of improving the crosslinking density of the polymer forming the pressure-sensitive adhesive layer is considered effective. However, as a result of intensive studies by the present inventors, as an index for achieving the crosslinking density, the storage elastic modulus G' of the pressure-sensitive adhesive layer at a high temperature, specifically, the value of the storage elastic modulus G' at 150°C measured at a frequency of 1 Hz is useful, and it was found that the storage elastic modulus G' at 150°C correlates with the resistance of the pressure-sensitive adhesive layer to the plasticizing action of the plasticizer. In the rubber elastic region at 150°C, since the entanglement of the molecular chains of the polymer in the pressure-sensitive adhesive layer is sufficiently unraveled, in that state, it is considered that the network structure formed by crosslinking of the molecular chains of the polymer mainly plays an elastic role. Therefore, it is presumed that the larger the value of the storage elastic modulus G' at 150°C, the more reliably and sufficiently the network structure of the polymer in the pressure-sensitive adhesive layer is formed, and the crosslinking density is improved. It is considered that the resistance of the pressure-sensitive adhesive layer to the plasticizing action of the plasticizer is improved by this improvement in the crosslinking density.

[0025] Based on the above findings, through repeated studies, even when the plasticizer migrates from the article to the pressure-sensitive adhesive layer during the period from temporarily fixing the article to re-peeling it, the degree of decrease in the cohesive force of the entire pressure-sensitive adhesive layer is significantly suppressed, and the lower limit value of the storage elastic modulus G' at 150°C, which serves as an index for achieving the crosslinking form of the natural rubber-based pressure-sensitive adhesive and the crosslinking density of the pressure-sensitive adhesive layer, capable of maintaining a certain cohesive force without causing glue residue on the article (adherend) during re-peeling, was found. On the other hand, it is also necessary to have both tack and adhesive strength that can reliably temporarily fix the article in a short time, which is another problem. When the crosslinking density of the polymer in the pressure-sensitive adhesive layer becomes excessively high, these adhesive properties deteriorate. From that viewpoint, the upper limit value of the storage elastic modulus G' at 150°C that can maintain these adhesive properties in a well-balanced manner was found.

[0026] The adhesive layer in the present invention has a storage elastic modulus G' at 150°C measured at a frequency of 1 Hz of 17,000 Pa or more and 55,000 Pa or less. The storage elastic modulus G' is measured using a dynamic viscoelasticity measuring device in accordance with JIS K7244-6. The measurement conditions shown in the examples can be used.

[0027] From the viewpoint of the resistance to the plasticizing action of the plasticizer in the adhesive layer, the lower limit of the storage elastic modulus G' of the adhesive layer at 150°C is preferably 20,000 Pa, more preferably 23,000 Pa, and still more preferably 27,000 Pa. When the storage elastic modulus G' at 150°C is less than 17,000 Pa, the polymer network structure of the adhesive layer is not surely and sufficiently formed, so the resistance to the plasticizing action of the plasticizer in the adhesive layer is insufficient. In particular, when an adhesive tape is adhered to the surface of a resin containing a plasticizer, adhesive residue is likely to remain on the adherend during peeling. From the viewpoint of maintaining a good balance between tack and adhesive strength, the upper limit of the storage elastic modulus G' of the adhesive layer at 150°C is preferably 52,000 Pa, more preferably 42,000 Pa, and still more preferably 40,000 Pa. When the storage elastic modulus G' at 150°C exceeds 55,000 Pa, the adhesive strength for fixing an article during adhesion may be insufficient, or it may not be possible to fix it quickly in a short time. More specifically, the storage elastic modulus G' at 150°C is preferably in the range of 20,000 Pa or more and 52,000 Pa or less, more preferably 23,000 Pa or more and 42,000 Pa or less, and still more preferably 27,000 Pa or more and 40,000 Pa or less. When the storage elastic modulus G' at 150°C is within the above range, for example, an article such as the above-described cable can be quickly and surely temporarily fixed to the floor surface in a short time, while it can be peeled off well without leaving adhesive residue.

[0028] <Natural rubber> The adhesive layer in the present invention contains natural rubber. Natural rubber is obtained by coagulating and drying natural rubber latex, which is the sap of rubber trees, and is a substance mainly composed of cis-1,4-polyisoprene.

[0029] The structure of natural rubber has not yet been clearly elucidated, but it is presumed to be a branched polymer with a basic skeleton consisting of a dimethylallyl group bonded to a functional group (starting end: ω end) that interacts with a protein, two trans-1,4-isoprene units, approximately 5,000 cis-1,4-isoprene units, and a cis-1,4-isoprene unit bonded to a phospholipid or fatty acid (stopping end: α end). That is, the protein terminals (starting end: ω end) of multiple natural rubber molecules interact and bind around the protein contained as a non-rubber component, and it is considered that the other phospholipid terminal (stopping end: α end) of natural rubber has a branched structure in which the phospholipid terminals of multiple natural rubbers interact and bind in a domain-like manner. In recent studies, it is presumed that five types of structures such as long-chain fatty acid esters or hydroxyl groups exist at the above-mentioned stopping end: α end. The non-rubber components such as the above-mentioned protein and phospholipid are contained in natural rubber at 3 to 4%.

[0030] Since natural rubber has an unsaturated bond (double bond) in the main chain skeleton of its molecule and also has a functional group at the end of the molecule, it can be easily crosslinked and cured with a crosslinking agent described later. In addition, since the pressure-sensitive adhesive composition according to the present invention crosslinks and cures, the crosslinked body is also referred to as a cured product.

[0031] Examples of the classification of natural rubber to be used include Technical Specified Rubber (TSR), Standard Malaysian Rubber (SMR), Standard Indonesian Rubber (SIR), High-Purity Natural Rubber (HPNR), Ribbed Smoked Sheet (RSS) Nos. 1 to 6, Pale Crepe Nos. 1 to 3, and the like.

[0032] In general, unvulcanized natural rubber has a very high molecular weight. If the molecular weight of natural rubber is too high, when it is made into a plasticized and adhesive composition, it lacks flexibility and may not be able to obtain appropriate adhesive properties. Therefore, it is necessary to mechanically knead it in advance using a pressure kneader, Banbury mixer, open roll, etc. to moderately reduce the molecular weight of natural rubber and adjust the plasticity for use in compounding.

[0033] In particular, as the plasticity of the natural rubber used in the adhesive composition of the present invention, the Mooney viscosity [ML(1+4)100°C], which is one of the indicators, is preferably 45 or more and 90 or less, and more preferably 50 or more and 65 or less. The Mooney viscosity is measured using a Mooney viscosity measuring device in accordance with JIS K6300 1 2013. The measurement conditions shown in the examples can be used. If the Mooney viscosity is too low or too high, it may not be possible to obtain an adhesive composition and an adhesive tape that can achieve both excellent adhesive strength and high cohesive force required for temporary fixing of articles.

[0034] <Crosslinking agent> Typical methods for crosslinking natural rubber include: (1) a method of crosslinking the molecular chains of natural rubber using a crosslinking agent such as a vulcanizing agent; and (2) a method of crosslinking through the reaction between the functional groups at the molecular ends of natural rubber, the functional groups of non-rubber components such as proteins and lipids, and the functional groups of the crosslinking agent.

[0035] In the method of crosslinking the molecular chains of natural rubber using a crosslinking agent such as the vulcanizing agent in (1) above, a crosslinking agent such as a sulfur-based, quinoid-based, or bismaleimide-based crosslinking agent or an additive used in combination acts on a plurality of unsaturated bonds (double bonds) contained in the main chain skeleton of the natural rubber molecules, extracts the hydrogen of the carbon (allylic position) adjacent to the unsaturated bond (double bond) of the natural rubber, and takes a reaction mechanism of crosslinking the molecular chains of the natural rubber. Therefore, it is possible to form a dense and strong (small-mesh) crosslinked structure, and the cohesive force of the adhesive layer can be increased. Since the crosslinking agent acting on the allylic carbon adjacent to the unsaturated bond (double bond) of natural rubber is difficult to proceed with the reaction, usually, in order to achieve crosslinking at a practical level, it is used in combination with additives such as a crosslinking accelerator and a crosslinking acceleration auxiliary agent described later, and the crosslinking reaction is allowed to proceed through the generated crosslinking precursor (reaction intermediate).

[0036] Also, in the method of crosslinking by the reaction between the molecular terminal functional groups of natural rubber in (2) above and the functional groups of non-rubber components such as proteins and lipids and the functional groups of the crosslinking agent, for example, in order to take a reaction mechanism of crosslinking the molecular terminal functional groups of natural rubber such as hydroxyl groups and carboxyl groups and the functional groups of non-rubber components such as proteins and lipids with a crosslinking agent having functional groups such as isocyanate groups, epoxy groups, and oxazoline groups capable of reacting with the functional groups, it is possible to form a crosslinked structure having an appropriate crosslinking density (slightly larger mesh), and the hardness of the adhesive layer can be made moderately soft. In the method by the reaction between the functional groups in (2) above, examples of the crosslinking agent include isocyanate-based compounds, epoxy-based compounds, oxazoline-based compounds, aziridine-based compounds, butylated melamine compounds, and the like.

[0037] Incidentally, when a plasticizer such as a phthalic acid ester acts on natural rubber, the polar part of the plasticizer is mainly attracted to the polar parts of proteins and lipids in the natural rubber, and solvation and lubrication actions occur starting from that part, and it is considered that the natural rubber is plasticized. When assuming a special situation where there is a plasticizer that has migrated from an article in the natural rubber-based adhesive layer, the inventor considered that in the natural rubber crosslinked by the crosslinking method by the reaction between the functional groups in (2) above, the plasticizing action by the above plasticizer cannot be sufficiently suppressed. That is, in the crosslinking method by the reaction between the functional groups in (2) above, although it is possible to perform a crosslinking reaction on the functional groups in natural rubber with a functional group such as the isocyanate group of the crosslinking agent, as described above, the molecular ends of natural rubber also have some interaction with proteins and lipids, so each functional group may have its reaction with the functional group of the crosslinking agent inhibited. Therefore, in the crosslinking method by the reaction between the functional groups in (2) above, the crosslinking of natural rubber mainly results in a crosslinked structure with a slightly large network crosslinked at the molecular ends, and there may be molecules that are not three-dimensionally crosslinked due to the above crosslinking inhibition, so it was considered that the plasticizing action by the plasticizer in the adhesive layer cannot be sufficiently suppressed.

[0038] Therefore, in view of the object of the present invention, the inventors considered that, instead of the crosslinking method by the reaction between the functional groups in (2) above, if the natural rubber molecular chains can be crosslinked as densely as possible to such an extent that the natural rubber does not become excessively hard by using a crosslinking agent such as the vulcanizing agent in (1) above, it would have good tack and excellent adhesive strength required for temporary fixing of articles, and a high initial cohesive strength. Even when a plasticizer migrates from the article to the adhesive layer during the period from temporarily fixing the article to re-peeling it, the degree of decrease in the cohesive strength of the entire adhesive layer can be significantly suppressed, and an excellent rubber-based adhesive capable of maintaining a certain cohesive strength without causing glue residue on the article (adherend) during re-peeling can be provided. And, among the crosslinking agents that act on the allylic carbon adjacent to the unsaturated bond (double bond) of the natural rubber, by using a crosslinking agent containing sulfur or a sulfur donor, it has been found that an adhesive layer can be obtained that simultaneously satisfies good tack for quickly temporarily fixing the article during sticking, excellent adhesive strength for reliably temporarily fixing the article, and good resistance to the plasticizing action of the plasticizer.

[0039] That is, as the crosslinking agent in the pressure-sensitive adhesive layer of the present invention, a crosslinking agent containing sulfur or a sulfur donor is used. The sulfur or sulfur donor may be used alone or in combination. Among these, from the viewpoint of enabling crosslinking at a lower temperature, it is preferable to use the sulfur donor as the crosslinking agent to crosslink natural rubber, which is the base polymer of the pressure-sensitive adhesive layer, by sulfur-free vulcanization. Since the sulfur donor releases sulfur by thermal decomposition, it is possible to perform vulcanization (sulfur-free vulcanization) without using elemental sulfur. Examples of the sulfur donor include thiuram compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, active tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram monosulfide, tetrabutylthiuram disulfide, N,N'-dimethyl-N,N'-diphenylthiuram disulfide, dipentamethylenethiuram monosulfide, dipentamethylenethiuram disulfide, dipentamethylenethiuram tetrasulfide, dipentamethylenethiuram hexasulfide, dicyclopentamethylenethiuram disulfide, mixed alkylthiuram disulfide, and tetrabenzylthiuram disulfide. Among these thiuram compounds, the thiuram compound particularly preferable from the viewpoint of environmental regulations is tetrabenzylthiuram disulfide.

[0040] As described above, as crosslinking agents that act on allylic carbon adjacent to a plurality of unsaturated bonds (double bonds) of natural rubber, in addition to sulfur-based crosslinking agents, there are quinoid-based crosslinking agents and bismaleimide-based crosslinking agents. However, quinoid-based crosslinking agents and bismaleimide-based crosslinking agents have a rigid ring structure in their skeletons. Therefore, natural rubber in which molecular chains are densely crosslinked via the rigid skeleton becomes hard. Then, the resistance to the plasticizing action of the plasticizer in the pressure-sensitive adhesive layer is good, but the tack required as an adhesive property decreases. In contrast, the crosslinking agent containing sulfur or a sulfur donor has a sulfur (-S-, -S-S-, -S XSince the molecular chains of natural rubber are closely crosslinked via sulfur (etc.), and since cyclic sulfide structures and pendant groups may be formed within the molecule without participating in the crosslinking, the crosslinked natural rubber does not become overly hard as in the case of using quinoid crosslinking agents or bismaleimide crosslinking agents. As a result, the adhesive layer can maintain good resistance to the plasticizing action of the plasticizer migrating from the article, that is, maintain a certain cohesive force such that no glue residue occurs on the article (adherend) during re-peeling, while also having good tack characteristics.

[0041] It is necessary to adjust the compounding amount of the crosslinking agent containing the sulfur or sulfur donor with respect to natural rubber so that the storage elastic modulus G' at 150 °C measured at a frequency of 1 Hz of the adhesive layer described above is 17,000 Pa or more and 55,000 Pa or less.

[0042] Regarding the compounding amount of the crosslinking agent containing the sulfur or sulfur donor, since the crosslinking form of natural rubber is complex, it cannot be generally stated. However, for example, it is preferably contained in the adhesive layer in an amount of 0.85 parts by mass or more and 2.8 parts by mass or less with respect to 100 parts by mass of natural rubber. The lower limit value of the compounding amount of the crosslinking agent is more preferably 1.4 parts by mass, and even more preferably 1.6 parts by mass. Also, the upper limit value of the compounding amount of the crosslinking agent is more preferably 2.7 parts by mass, and even more preferably 2.2 parts by mass. More specifically, the compounding amount of the crosslinking agent is more preferably 1.4 parts by mass or more and 2.7 parts by mass or less, and even more preferably 1.6 parts by mass or more and 2.2 parts by mass or less. By adjusting the content of the crosslinking agent within the above range as a guideline, it becomes easy for the adhesive layer to satisfy each characteristic including the storage elastic modulus G' at 150 °C.

[0043] <Crosslinking accelerator, crosslinking accelerator aid> The pressure-sensitive adhesive layer in the present invention preferably contains a crosslinking accelerator. In this specification, the crosslinking accelerator refers to a catalyst that increases the rate of the crosslinking reaction by a crosslinking agent. Examples of such crosslinking accelerators include thiourea compounds such as diethylthiourea and trimethylthiourea; thiazole compounds such as 2-mercaptobenzothiazole, 2-(morpholinodithio)benzothiazole, and dibenzothiazyl disulfide; sulfenamide compounds such as N-cyclohexyl-2-benzothiazole sulfenamide and N-t-butyl-2-benzothiazole sulfenamide; thiuram compounds such as tetramethylthiuram disulfide and tetramethylthiuram monosulfide; dithiocarbamate compounds such as zinc dimethyldithiocarbamate; and guanidine compounds such as diphenylguanidine. Further, in the pressure-sensitive adhesive layer in the present invention, as a crosslinking acceleration aid together with the above crosslinking accelerator, metal oxides such as zinc oxide and fatty acids such as stearic acid may be used in combination.

[0044] The content of the crosslinking accelerator is not particularly set. However, if the addition amount of the crosslinking accelerator is too large, its effect will be saturated and there is a risk of contaminating the adherend. Also, if it is too small, the addition effect of the crosslinking accelerator may not be fully exerted. The content of the crosslinking accelerator is preferably 10 parts by mass or less, preferably 0.1 part by mass or more and 8 parts by mass or less, more preferably 0.2 part by mass or more and 5 parts by mass or less, based on 100 parts by mass of natural rubber. Further, the content of the crosslinking acceleration aid is not particularly set, but is preferably 50 parts by mass or less, preferably 0.5 part by mass or more and 25 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, based on 100 parts by mass of natural rubber.

[0045] <Adhesion-imparting resin> The pressure-sensitive adhesive layer in the present invention contains a tackifier resin. As the tackifier resin, a tackifier resin having good compatibility with natural rubber can be used, and at least one resin selected from the group consisting of petroleum resins, terpene resins, rosin resins, and other resins can be used. From the viewpoints of adhesion characteristics and resistance to the plasticizing action of plasticizers, the softening point of the above-mentioned tackifier resin is preferably 110°C or higher and 140°C or lower, and the solubility parameter (SP value) is more preferably 7.5 or higher and 8.4 or lower. Among these, from the viewpoint of better balance between adhesion characteristics and resistance to the plasticizing action of plasticizers, as the tackifier resin, an alicyclic saturated hydrocarbon resin (hydrogenated alicyclic hydrocarbon resin) having a softening point of 110°C or higher and 140°C or lower and a solubility parameter (SP value) of 7.5 or higher and 8.4 or lower is preferably used. If the softening point of the tackifier resin is less than 110°C, there is a risk that sufficient adhesive force cannot be obtained, and there is also a risk that the releasability, including resistance to the plasticizing action of plasticizers, becomes insufficient. Also, if the softening point exceeds 140°C, there is a risk that the tack decreases. When the SP value of the tackifier resin is within the above range, since it is easily compatible with natural rubber having an SP value of about 7.9 to 8.4, uniform and good adhesion characteristics can be obtained. On the other hand, since it is difficult to be compatible with phthalate esters having an SP value of about 8.6 to 8.9, which are typical plasticizers for vinyl chloride resins, when a plasticizer migrates from an article to the pressure-sensitive adhesive layer, the tackifier resin itself that is not cross-linked in the pressure-sensitive adhesive layer is less likely to be affected by the plasticizing action of the plasticizer. Therefore, the pressure-sensitive adhesive layer has good adhesion characteristics and resistance to the plasticizing action of plasticizers.

[0046] The pressure-sensitive adhesive resin can be well a commercially available product. Specifically, "Alcon P-115 (softening point: 115°C, SP value: 8.1)", "Alcon P-125 (softening point: 125°C, SP value: 8.1)", "Alcon P-140 (softening point: 140°C, SP value: 8.1)" (all are trade names), which are alicyclic saturated hydrocarbon resins manufactured by Arakawa Chemical Industries, Ltd., "T-REZ HA125 (softening point 125°C)", "T-REZ OP501 (softening point 138°C)" (all are trade names), which are hydrogenated alicyclic hydrocarbon resins manufactured by Standard Oil Osaka Sales Office Co., Ltd., "Clearon P125 (softening point: 125°C, SP value: 8.2)" (trade name), which is a hydrogenated terpene resin manufactured by Yasuhara Chemical Co., Ltd., "PlastolynR1140 (softening point: 140°C, SP value: 8.1)" (trade name), which is an aliphatic hydrocarbon resin manufactured by Eastman Chemical Co., Ltd., "Oppera PR-100 (softening point 120°C, SP value 8.4)" (trade name), which is a hydrogenated cyclopentadiene resin manufactured by ExxonMobil Chemical Co., Ltd., etc. can be mentioned.

[0047] The above SP value is a parameter for determining the activity of each component in a multi-component system, which is determined based on the theory of Hildebrand's regular solution, and means the SP value calculated by the Small method using the Hoy constant according to the following formula (I). SP value (δ)=d*(ΣG) / M (I) [d: density (g / ml), G: molecular attraction constant of each functional group of Hoy, M: molecular weight (g / mol)]

[0048] The content of the above-mentioned tackifier resin is preferably 80 parts by mass or more and 175 parts by mass or less with respect to 100 parts by mass of natural rubber. As the lower limit value of the content of the tackifier resin, it is more preferably 100 parts by mass, and even more preferably 105 parts by mass. Also, as the upper limit value of the content of the tackifier resin, it is more preferably 150 parts by mass, and even more preferably 130 parts by mass. More specifically, the content of the tackifier resin is more preferably 100 parts by mass or more and 150 parts by mass or less, and even more preferably 105 parts by mass or more and 130 parts by mass or less. If the content of the tackifier resin is less than 80 parts by mass, there is a possibility that sufficient 180° peel adhesion cannot be obtained. On the other hand, if the content of the tackifier resin exceeds 175 parts by mass, there is a possibility that the tack of the adhesive layer decreases or the crosslinking of natural rubber is inhibited. By adjusting the content of the tackifier resin within the above range, while maintaining a certain cohesive force of the adhesive layer against the plasticizing action of the plasticizer, that is, no glue residue occurs on the article (adherend) during re-peeling, the characteristics of 180° peel adhesion and tack can be satisfied.

[0049] <Softening agent> The adhesive layer in the present invention contains a softening agent. As the above-mentioned softening agent, for example, paraffinic process oil, naphthenic process oil, aromatic process oil, other process oils, liquid polyisoprene, liquid polybutadiene, liquid styrene-butadiene rubber, liquid polybutene, other liquid rubbers, etc. can be preferably used. Among these, from the viewpoints of adhesion and particularly ease of adjusting tack, a mixture of solvent-refined high-viscosity naphthene and hydrogenated medium-viscosity paraffin, which is a naphthenic process oil or other process oil, is preferably used.

[0050] Specific examples of the above-mentioned paraffinic process oil include Diana Process Oil PW-2, Diana Process Oil PW-90, etc. (both are trade names) manufactured by Idemitsu Kosan Co., Ltd. Also, Process Oil P100(K), Process Oil P200(K), Process Oil P300(K), Process Oil P400(K), Process Oil P500S, etc. (all are trade names) manufactured by JXTG Energy Corporation can be mentioned.

[0051] Specific examples of the naphthenic process oil include Diana Process Oil NP-24 (a mixture of solvent-refined high-viscosity naphthene and solvent-refined low-viscosity naphthene), Diana Process Oil NR-26 (main component: solvent-refined high-viscosity naphthene), Diana Process Oil NR-68 (main component: solvent-refined high-viscosity naphthene), Diana Process Oil NM-280 (main component: solvent-refined high-viscosity naphthene), etc. (all are trade names) manufactured by Idemitsu Kosan Co., Ltd. Also, examples include Crisef Oil H22, Crisef Oil H68, Crisef Oil H100, etc. (all are trade names) manufactured by JXTG Energy Corporation.

[0052] Specific examples of the aromatic process oil include Diana Process Oil AC-12, Diana Process Oil AC-460, etc. (all are trade names) manufactured by Idemitsu Kosan Co., Ltd. Also, examples include Barrel Process Oil B-01, Barrel Process Oil B-03, Barrel Process Oil B-04AB, Barrel Process Oil B-05, Barrel Process Oil B-28AN, Barrel Process Oil B-30, etc. (all are trade names) manufactured by Matsumura Oil Co., Ltd.

[0053] Specific examples of other process oils include Diana Process Oil NP-250 (a mixture of solvent-refined high-viscosity naphthene and hydrotreated medium-viscosity paraffin), Diana Process Oil NS-90S (a mixture of solvent-refined high-viscosity naphthene and hydrotreated medium-viscosity paraffin), Diana Process Oil NS-100 (a mixture of solvent-refined high-viscosity naphthene and hydrotreated medium-viscosity paraffin), etc. (all are trade names) manufactured by Idemitsu Kosan Co., Ltd. Also, examples include Cumic Process Oil L-NC, Cumic Process Oil 8465, etc. (all are trade names) manufactured by Shin Nippon Oil & Fat Co., Ltd.

[0054] Specific examples of the above liquid polyisoprene include Kuraprene KL-10, Kuraprene LIR-30, Kuraprene LIR-50, Kuraprene LIR-310, Kuraprene LIR-390, Kuraprene LIR-403, Kuraprene LIR-410, Kuraprene LIR-290, Kuraprene LIR-700, etc. (all are trade names) manufactured by Kuraray Co., Ltd. Also, Poly ip, etc. (all are trade names) manufactured by Idemitsu Kosan Co., Ltd. can be mentioned.

[0055] Specific examples of the above liquid polybutadiene include Kuraprene LBR-300, Kuraprene LBR-302, Kuraprene LBR-305, Kuraprene LBR-307, Kuraprene LBR-352, Kuraprene LBR-361, etc. (all are trade names) manufactured by Kuraray Co., Ltd. Also, Ricon130, Ricon131, Ricon134, Ricon142, Ricon150, Ricon152, Ricon153, Ricon154, Ricon156, Ricon157, etc. (all are trade names) manufactured by Cray Valley (USA) can be mentioned. Also, Poly bd R-15HT, Poly bd R-45HT, etc. (all are trade names) manufactured by Idemitsu Kosan Co., Ltd. can be mentioned.

[0056] Specific examples of the above liquid styrene-butadiene rubber include Kuraprene L-SBR-820, Kuraprene L-SBR-841, etc. (all are trade names) manufactured by Kuraray Co., Ltd. Also, Ricon100, Ricon181, Ricon184, etc. (all are trade names) manufactured by Cray Valley (USA) can be mentioned.

[0057] Specific examples of the above liquid polybutene include NOF Polybutene 0N, NOF Polybutene 015N, NOF Polybutene 3N, NOF Polybutene 10N, NOF Polybutene 30N, NOF Polybutene 200N, etc. (all are trade names) manufactured by NOF Corporation. Also, Nisseki Polybutene LV-7, Nisseki Polybutene LV-50, Nisseki Polybutene LV-100, Nisseki Polybutene HV-15, Nisseki Polybutene HV-35, Nisseki Polybutene HV-50, Nisseki Polybutene HV-100, etc. (all are trade names) manufactured by JXTG ENERGY Corporation can be mentioned.

[0058] The content of the softening agent is preferably 36 parts by mass or more and 44 parts by mass or less with respect to 100 parts by mass of natural rubber. As the lower limit value of the content of the softening agent, it is more preferably 37 parts by mass, and even more preferably 38 parts by mass. Also, as the upper limit value of the content of the softening agent, it is more preferably 43 parts by mass, and even more preferably 4 parts by mass. 2 parts by mass. More specifically, the content of the softening agent is more preferably 37 parts by mass or more and 43 parts by mass or less, and even more preferably 38 parts by mass or more and 42 parts by mass or less. If the content of the softening agent is less than 36 parts by mass, sufficient tack may not be obtained. On the other hand, if the content of the softening agent exceeds 44 parts by mass, the low molecular weight components increase and the cohesive force of the adhesive layer becomes excessively low, so the resistance of the adhesive layer to the plasticizing action of the plasticizer may decrease. By adjusting the content of the softening agent within the above range, it is possible to satisfy the 180° peel adhesive strength and tack characteristics while maintaining a certain cohesive force of the adhesive layer against the plasticizing action of the plasticizer, that is, without leaving glue residue on the article (adherend) during re-peeling.

[0059] <Other additives> In the adhesive layer of the present invention, one or more of an inorganic filler, an organic filler such as a resin, a plasticizer, a surfactant, a coupling agent, a coloring agent, a preservative, an antioxidant, a heat stabilizer, a light stabilizer, etc. may be further added as long as the above physical properties are not impaired. For example, the content of the above inorganic filler is preferably 230 parts by mass or less with respect to 100 parts by mass of natural rubber, the content of the above coloring agent is preferably 10 parts by mass or less with respect to 100 parts by mass of natural rubber, and the content of the antioxidant is preferably 5 parts by mass or less with respect to 100 parts by mass of natural rubber.

[0060] <Sheet-like substrate> The type of the sheet-like substrate in the present invention is not particularly limited, and any sheet-like material such as a known film, foam, woven fabric, knitted fabric, non-woven material such as paper, etc. that is usually used may be used.

[0061] Among the above-mentioned base materials, in the case of an adhesive tape used for temporarily fixing the above-mentioned power and information communication cable to the floor, from the viewpoints of the cutability and followability of the adhesive tape, a woven fabric obtained by plain weaving rayon spun yarn, polyester spun yarn, a blended yarn of rayon and polyester, polyester filament yarn, polyethylene flat yarn, etc., or a warp knitted fabric obtained by independently knitting multifilaments and inserting flat yarn as a weft yarn, etc. It is preferable to use a base material in which a resin layer such as polyethylene is provided on one or both sides of the base fabric by lamination.

[0062] Furthermore, the thickness of the sheet-like base material can be appropriately selected and used within a range that can maintain the strength and flexibility required for the adhesive tape, but the thickness is preferably 10 to 300 μm, more preferably 50 to 250 μm, and even more preferably 60 to 200 μm.

[0063] <Release treatment agent> In the case of a single-sided adhesive tape as shown in Fig. 1, an adhesive layer 12 is formed on one surface 11a of the base material 11, and when wound into a roll, the adhesive layer will contact the other surface 11b of the base material. In order to improve the drawability from the roll, it is preferable to form a release layer on the surface 11b. The release treatment agent used for this release layer is not particularly limited, and any one can be used as long as it exhibits the effect. For example, silicone resin, long-chain alkyl vinyl monomer polymer, fluorinated alkyl vinyl monomer polymer, polyvinyl alcohol carbamate, etc. are known. Among these, silicone resin is excellent in the property of improving the peeling performance of the base material surface. The adhesion amount or basis weight of the release layer after drying is usually 0.2 to 2 g / m 2 , preferably 0.4 to 1.2 g / m 2 is.

[0064] <Release sheet> In the case of a double-sided adhesive tape as shown in Fig. 2, it is preferable from the viewpoint of handleability to laminate a release sheet on the outer surface of the adhesive layer in a peelable manner. Further, when winding into a roll shape, it can be wound such that a release sheet is sandwiched between the adhesive layer 22 and the adhesive layer 23. Since the release sheet does not particularly require high strength, for example, a sheet-like material such as glassine paper or kraft paper having the above-described release treatment applied to one or both sides can be used.

[0065] <Method for manufacturing an adhesive tape> Regarding the adhesive composition used for the adhesive layer 12 in Fig. 1 and the adhesive layers 22 and / or 23 in Fig. 2, the manufacturing method is not particularly limited. However, in the present invention, a batch-type kneading device such as a pressure kneader, a Banbury mixer, a mixing roll, etc., and a continuous kneading device such as a twin-screw kneader are used to gradually blend the components of the adhesive composition and knead them while heating to prepare the adhesive composition. Specifically, for example, first, the above-described natural rubber and tackifier resin are blended into a pressure kneader, and if necessary, a crosslinking accelerator, an inorganic filler such as fine calcium carbonate powder, an antioxidant, etc. are blended at an appropriate ratio, and heated and kneaded without using any organic solvent or water. Further, a crosslinking agent and a softening agent are added thereto and the heating and kneading are continued, so that the crosslinking agent is uniformly dispersed in the kneaded product, and at the same time, a uniform crosslinking reaction is carried out between this and the polymer of the natural rubber, and an adhesive composition having a structure in which the polymer of the natural rubber is densely crosslinked can be obtained.

[0066] The above manufacturing method is merely an example and is not limited thereto. For example, it is also possible to produce the pressure-sensitive adhesive composition by changing and adjusting the blending amounts and charging order of the respective components, or by using an appropriate organic solvent. When heat-kneading, the kneading temperature is appropriately selected according to the composition of the pressure-sensitive adhesive composition, the batch amount of the blend, the capacity of the kneading apparatus, etc. within a temperature range of about 100 to 200°C, preferably 110 to 180°C. The kneading time is in the range where the total kneading time of the respective components is 3 to 60 minutes, preferably 4 to 30 minutes, according to the kneading temperature. While observing the torque and kneading state during kneading, the end point of the torque increase after adding the crosslinking agent is judged as the end point of the crosslinking reaction, and the time is appropriately selected.

[0067] The pressure-sensitive adhesive composition thus crosslinked by heat-kneading easily softens when heated and has good formability. Therefore, this pressure-sensitive adhesive composition is heat-coated onto a substrate 11 or 12 provided with a polyethylene resin layer on one or both sides of a woven fabric obtained by plain-weaving rayon yarns by laminating, using a calendar roll, an extruder, or the like, to produce a pressure-sensitive adhesive sheet in the form of a sheet, tape, film, etc. provided with a pressure-sensitive adhesive layer 12 and / or 22 and / or 23 made of the above pressure-sensitive adhesive composition on the above substrate. In this manufacturing method, since an organic solvent that causes environmental pollution or water that requires a large amount of energy during drying is not used, it is not necessary to provide a heating step using a drying furnace after substrate coating, which is friendly to the global environment and can greatly contribute to energy saving.

[0068] The thickness of the above pressure-sensitive adhesive layer is not particularly limited and may be anything as long as it exhibits excellent adhesive strength, tack, and cohesion required for temporary fixing of articles. Usually, it is about 50 to 500 μm, preferably 60 to 300 μm.

[0069] Also, on the surface (surface 11a) of the sheet-like base material 11 in FIG. 1 that faces the adhesive layer 12, surface treatment such as corona discharge treatment or plasma treatment may be performed as necessary, an undercoat layer may be provided, or both may be performed, thereby improving the adhesion of the adhesive layer 12 to the base material 11. Further, on the surface 11b of the sheet-like base material 11 in FIG. 1 opposite to the surface 11a, a release layer may be provided as necessary to prevent the adhesive composition from adhering to the surface 11b of the base material 11 when the adhesive tape of this embodiment is wound into a roll shape, and to maintain the ease of rewinding (pulling out).

[0070] Also, on both surfaces (21a and 21b) or either one surface of the sheet-like base material 21 in FIG. 2, surface treatment such as corona discharge treatment or plasma treatment may be performed as necessary, an undercoat layer may be provided, or both may be performed, thereby improving the adhesion between the adhesive layer 22 or the adhesive layer 23 and the base material 21.

Example

[0071] Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, "parts" means "parts by mass".

[0072] The materials used in the examples and comparative examples are as follows.

[0073]

Table 1

[0074] <Examples 1 to 7, Comparative Examples 1 and 2> Table 5 shows the components and composition of the adhesive layer. For the natural rubber "SVR-CV60", when the Mooney viscosity ML(1+4) 100°C was measured using a Mooney viscosity measuring device "SMV 200P" (trade name) manufactured by Shimadzu Corporation under the following conditions, it was 53.

[0075]

Table 2

[0076] The components of the first charge were dropped, and heat kneading was carried out at 120 °C for 1 minute and 30 seconds from the rise in torque using a 3 L pressure kneader to obtain the first charge compound. With respect to the first charge compound, the components of the second charge were dropped, and continuous kneading was carried out for 1 minute and 30 seconds to obtain the second charge compound. With respect to the second charge compound, the components of the third charge were dropped, and heat kneading was carried out judging the end point of the torque rise as the end point of the crosslinking reaction to obtain the adhesive composition. The final temperature after kneading the components of the third charge was 160 °C.

[0077] Using the above adhesive composition, an adhesive layer was formed by calendar coating at 100 °C on the side of the nonwoven fabric of a 0.20 mm thick substrate with polyethylene laminated on one side of the nonwoven fabric so that the thickness of the adhesive layer was 0.10 mm, and an adhesive tape having a single-sided adhesive layer as shown in Fig. 1 was obtained. The following evaluations were carried out on the obtained adhesive tape. Incidentally, the polyethylene surface side (the side where the adhesive layer is not formed) of the above substrate is subjected to a release treatment and a mat processing treatment.

[0078] <Storage elastic modulus G’> Regarding the adhesive layer of the adhesive tape, a dynamic viscoelastic spectrum was measured under the solid shear mode and the following measurement conditions using a dynamic viscoelasticity measuring device "DMS6100" (trade name) manufactured by Hitachi High-Tech Science Corporation, and the shear storage elastic modulus G’ at 150 °C was determined. The results are shown in Table 5.

[0079]

Table 3

[0080] <180° Peel adhesion> The adhesive tape was attached to a BASUS board, crimped and cured, and peeled at 180° under the following measurement conditions using a tensile testing machine to measure the peel force (N / 10 mm). The results are shown in Table 5.

[0081]

Table 4

[0082] <Tack The tack of the adhesive layer was evaluated by an inclined ball tack in accordance with JIS-Z0237. Specifically, a triangular device (inclination angle: 30 degrees) having an inclined surface with a starting point for placing a hard sphere, a walking aid path (100 mm) following the starting point, and an adhesive layer surface (100 mm) of an adhesive tape following the walking aid path was prepared. A hard sphere (size: 1 / 32 to 32 / 32 inches) was rolled from the starting point above the inclined surface toward the adhesive layer surface below the inclined surface. The numerical value 32 times the size of the ball that stopped on the adhesive layer surface was called the "ball number", and the maximum ball number that stopped on each adhesive tape was measured. The results are shown in Table 5.

[0083] <PVC paste residue performance As an adherend for the paste residue test, a soft PVC cord (vinyl cab tire round cord "VCTF2SQ×6C" (trade name) manufactured by Fujidenko Co., Ltd.) was prepared. The soft PVC covering the cord contains a phthalate plasticizer as a plasticizer. An adhesive tape was wound around the outer periphery of the cord once and sufficiently crimped by hand. The cord with the adhesive tape wound around it was placed in a thermostatic chamber at a temperature of 65 °C and a relative humidity of 80%, and after a predetermined number of days (1, 3, 7, 10 days) had elapsed, the adhesive tape was slowly peeled off by hand. The presence or absence of paste residue on the adherend at this time was confirmed. The results are shown in Table 5. No paste residue indicates excellent performance, and the presence of paste residue means poor performance. For example, "no paste residue after 7 days" in the PVC paste residue evaluation in Table 5 means that there was no paste residue confirmed after 7 days, but there was paste residue confirmed after 10 days.

[0084]

Table 5

Explanation of reference numerals

[0085] 11, 21... base materials, 12, 22, 23... adhesive layers.

Claims

1. An adhesive tape having a base material and an adhesive layer formed on the base material, wherein the adhesive layer contains natural rubber, a crosslinking agent, an adhesion - imparting resin, and a softening agent, and the storage elastic modulus G' at 150°C measured at a frequency of 1 Hz is in the range of 17,000 Pa or more and 55,000 Pa or less, wherein the crosslinking agent is a crosslinking agent containing sulfur or a sulfur donor, and the adhesive tape has a 180° peel adhesion to a SUS plate of 0.9 N / 10 mm or more and a tack at an inclination angle of 30 degrees of 17 or more.

2. The adhesive tape according to claim 1, wherein the crosslinking agent is contained in an amount of 0.85 parts by mass or more and 2.8 parts by mass or less based on 100 parts by mass of the natural rubber.

3. The adhesive tape according to claim 1 or 2, wherein the adhesion - imparting resin is contained in an amount of 80 parts by mass or more and 175 parts by mass or less based on 100 parts by mass of the natural rubber.

4. The adhesive tape according to claim 1, wherein the adhesion - imparting resin has a softening point of 110°C or more and 140°C or less and a solubility parameter (SP value) of 7.5 or more and 8.4 or less.

5. The adhesive tape according to claim 1, wherein the softening agent is contained in an amount of 36 parts by mass or more and 44 parts by mass or less based on 100 parts by mass of the natural rubber.

6. The adhesive tape according to claim 1, wherein the storage elastic modulus G' at 150°C measured at a frequency of 1 Hz of the adhesive layer is in the range of 20,000 Pa or more and 52,000 Pa or less.

7. The adhesive tape according to claim 1, wherein the sulfur donor is a thiuram - based compound.

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