Hot melt adhesive composition and adhesive tape using the hot melt adhesive composition

Abstract

To provide an adhesive composition that has sufficient initial adhesion and allows for both of re-sealing and easy opening, and an adhesive tape including the adhesive composition.SOLUTION: A hot-melt adhesive composition comprises a styrenic elastomer, an olefinic elastomer, and a tackifier. The hot-melt adhesive composition comprises the styrenic elastomer of 2 wt.%-80 wt.%, the olefinic elastomer of 2 wt.%-50 wt.%, and the tackifier of 2 wt.%-40 wt.%.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a hot melt pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape using the hot melt pressure-sensitive adhesive composition. [Background technology]

[0002] Packaging containers such as bags are known that have a fastener attached to the opening so that the bag can be resealed after some of the contents, such as food or detergent, have been removed. The process of attaching a fastener to a bag is complicated and increases manufacturing costs, so alternative bags with a resealable function have been studied. As a bag with a resealable function, a bag with a resealable portion has been proposed (for example, Patent Document 1).

[0003] Also, a method is known in which adhesive tape is used to fix the opening of a packaging container so that it does not open when resealing the container. Adhesive tapes used for resealing are required to be resealable and easy to open. However, even if the tape has suitable adhesive properties at the time of production, its adhesive strength may increase over time, which may result in damage to the packaging container when it is opened. This tendency may be more pronounced in packaging materials that have been printed and surface-treated. Furthermore, if the adhesive strength is adjusted taking into account the increase in adhesive strength over time, sufficient adhesive strength may not be exhibited during the manufacturing stage. Therefore, there is a demand for an adhesive composition that has sufficient initial adhesive strength and is capable of achieving both resealable and easy to open properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-15244 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a pressure-sensitive adhesive composition that has sufficient initial adhesive strength and is capable of achieving both resealability and easy opening, and a pressure-sensitive adhesive tape using the pressure-sensitive adhesive composition. [Means for solving the problem]

[0006] A hot melt pressure-sensitive adhesive composition according to an embodiment of the present invention comprises a styrene elastomer, an olefin elastomer, and a tackifier, and the hot melt pressure-sensitive adhesive composition contains 2 to 80% by weight of the styrene elastomer, 2 to 50% by weight of the olefin elastomer, and 2 to 40% by weight of the tackifier. In one embodiment, the hot melt pressure-sensitive adhesive composition contains 5% by weight to 40% by weight of the olefin elastomer. In one embodiment, the olefin-based elastomer comprises an α-olefin-based elastomer. In one embodiment, the α-olefin elastomer includes at least one selected from an ethylene elastomer, a propylene elastomer, and a 1-butene elastomer. In one embodiment, the α-olefin-based elastomer is a propylene-based elastomer. In one embodiment, the α-olefin elastomer has a softening point of less than 100°C. In one embodiment, the styrene content of the styrene-based elastomer is 10% by weight to 25% by weight. In one embodiment, the styrenic elastomer comprises a styrene-isoprene block copolymer. In one embodiment, the styrene-isoprene block copolymer comprises a diblock copolymer. In one embodiment, the styrene-isoprene block copolymer comprises 5% to 70% by weight of a diblock copolymer. In one embodiment, the hot melt pressure-sensitive adhesive composition contains 4 wt % to 30 wt % of the tackifier. In one embodiment, the tackifier is a hydrogenated petroleum resin. In one embodiment, the hot melt pressure-sensitive adhesive composition further comprises oil. In one embodiment, the pressure-sensitive adhesive composition contains 5% to 30% by weight of oil. In one embodiment, the hot melt pressure-sensitive adhesive composition has a viscosity at 160°C of less than 50,000 mPa·s. In another aspect of the present invention, there is provided a pressure-sensitive adhesive tape, which comprises a substrate and a pressure-sensitive adhesive layer containing the hot-melt pressure-sensitive adhesive composition, and the pressure-sensitive adhesive layer has a thickness of 10 μm to 100 μm. In one embodiment, the pressure-sensitive adhesive tape has an initial adhesive strength AF0 of 0.1 N / 10 mm to 5.0 N / 10 mm and an adhesive strength AF s is 0.1N / 10mm~5.0N / 10mm. In one embodiment, the pressure-sensitive adhesive tape is used as a resealing sealant. In one embodiment, the pressure-sensitive adhesive tape is used for packaging material having a printed portion. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a pressure-sensitive adhesive composition that has sufficient initial adhesive strength and is capable of achieving both resealability and easy opening, and a pressure-sensitive adhesive tape using the pressure-sensitive adhesive composition. [Brief explanation of the drawings]

[0008] [Figure 1A] 1 is a schematic cross-sectional view of an adhesive tape according to one embodiment of the present invention. [Figure 1B] FIG. 2 is a schematic cross-sectional view of an adhesive tape according to another embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a usage mode of the pressure-sensitive adhesive tape shown in FIG. 1B. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. Hot melt adhesive composition A hot melt pressure-sensitive adhesive composition according to an embodiment of the present invention comprises a styrene elastomer, an olefin elastomer, and a tackifier. This hot melt pressure-sensitive adhesive composition comprises 2% to 80% by weight of the styrene elastomer, 2% to 50% by weight of the olefin elastomer, and 2% to 40% by weight of the tackifier, relative to 100% by weight of the hot melt pressure-sensitive adhesive composition. This composition provides a pressure-sensitive adhesive composition that has sufficient initial adhesive strength and is capable of achieving both resealability and easy opening. The physical properties (particularly adhesive strength) of the pressure-sensitive adhesive composition may also change if the packaging material to be adhered is surface-treated or has a printed surface. The hot melt pressure-sensitive adhesive composition according to an embodiment of the present invention can achieve both resealability and easy opening, even when applied to a packaging material with a printed surface.

[0010] The viscosity of the hot-melt pressure-sensitive adhesive composition at 160°C is preferably less than 50,000 mPa·s, more preferably 40,000 mPa·s or less, and even more preferably 30,000 mPa·s or less. The viscosity of the hot-melt pressure-sensitive adhesive composition at 160°C is preferably 1,000 mPa·s or more. If the viscosity at 160°C is within the above range, the coatability is improved, and the productivity of pressure-sensitive adhesive tapes using the hot-melt pressure-sensitive adhesive composition can be improved. In this specification, the viscosity of the hot-melt pressure-sensitive adhesive composition refers to the viscosity measured with a viscometer (for example, Brookfield Model: DVE Viscometer, Spindle: LV).

[0011] The hot melt pressure sensitive adhesive composition preferably has a loss modulus E″ of 356×10 4 Pa or less, and more preferably 100×10 4 Pa or less, and more preferably 50×10 4 The hot melt pressure-sensitive adhesive composition has a loss modulus E″ of 10×10 4When the loss modulus E" is in the above range, it is possible to provide a hot-melt pressure-sensitive adhesive composition that has sufficient initial adhesive strength and is capable of achieving both resealability and easy opening. The loss modulus E" can be measured, for example, by using a nanoindenter.

[0012] A-1. Styrene-based elastomer The hot melt pressure-sensitive adhesive composition contains 2 to 80% by weight of a styrene elastomer relative to 100% by weight of the hot melt pressure-sensitive adhesive composition. The hot melt pressure-sensitive adhesive composition preferably contains 10 to 75% by weight of the styrene elastomer, more preferably 20 to 75% by weight, even more preferably 30 to 70% by weight, and particularly preferably 40 to 65% by weight. By ensuring that the content of the styrene elastomer is within the above range, it is possible to provide a pressure-sensitive adhesive composition that has sufficient initial adhesive strength and is capable of achieving both resealability and easy opening.

[0013] The styrene content of the styrene elastomer can be set to any appropriate value. The styrene content of the styrene elastomer is preferably 10% by weight or more, more preferably 12% by weight or more, and even more preferably 14% by weight or more. If the styrene content of the styrene elastomer is less than 10% by weight, the initial adhesive strength may be excessively high, and adhesive residue may be left behind upon peeling. The styrene content of the styrene elastomer is preferably 25% by weight or less, more preferably 20% by weight or less, and even more preferably 18% by weight or less. If the styrene content of the styrene elastomer exceeds 25% by weight, the adhesive strength may increase over time, and easy opening may not be achieved. Furthermore, there is a risk of damaging the adherend, such as a packaging material.

[0014] The melt flow rate (MFR) of the styrene elastomer is preferably 5 g / 10 min to 40 g / 10 min, more preferably 10 g / 10 min to 30 g / 10 min, and even more preferably 20 g / 10 min to 30 g / 10 min. Having an MFR in the above range can improve the coatability of the hot-melt pressure-sensitive adhesive composition. In this specification, MFR refers to a value measured at 200°C and 5 kg using the method described in ISO 1133.

[0015] Any suitable styrene-based elastomer can be used. Examples include styrene-isoprene block copolymer (SIS), styrene-butadiene block copolymer (SBS), styrene-ethylenebutylene block copolymer (SEBS), styrene-ethylenepropylene block copolymer (SEPS), styrene-ethyleneethylenepropylene block copolymer (SEEPS), and styrene-butadiene-butene-styrene block copolymer (SBBS). These may be used alone or in combination of two or more. Preferably, styrene-isoprene block copolymer (hereinafter also referred to as SIS) can be used.

[0016] The SIS preferably contains a diblock copolymer, which makes it possible to adjust the initial adhesive strength to an appropriate value and also improve the wettability of the hot-melt pressure-sensitive adhesive composition.

[0017] The content of the SIS diblock copolymer in the SIS is preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 30% by weight or more. By having the content of the SIS diblock copolymer in the above range, the initial adhesive strength can be adjusted to an appropriate value, and the wettability of the hot-melt pressure-sensitive adhesive composition can also be improved. The content of the SIS diblock copolymer in the SIS is preferably 80% by weight or less, more preferably 50% by weight or less, even more preferably 40% by weight or less, and most preferably 35% by weight or less. When the content of the SIS diblock copolymer is in the above range, adhesive residue on the adherend can be prevented.

[0018] A-2. Olefin elastomer The hot melt pressure-sensitive adhesive composition contains 2% by weight to 50% by weight of an olefin elastomer. The content of the olefin elastomer is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, and particularly preferably 20% by weight or more. When the content of the olefin elastomer is within the above range, a pressure-sensitive adhesive composition that can achieve both resealability and easy opening properties can be provided. The content of the olefin elastomer is preferably 40% by weight or less, more preferably 35% by weight or less, and even more preferably 30% by weight or less. When the content of the olefin elastomer is within the above range, the initial adhesive strength can be adjusted to an appropriate value.

[0019] The density of the olefinic elastomer is preferably 0.830 g / cm 3 More preferably, it is 0.835 g / cm or more. 3 More preferably, it is 0.840 g / cm 3 More preferably, it is 0.845 g / cm 3 The density of the olefin elastomer is preferably 0.890 g / cm 3 or less, more preferably 0.885 g / cm 3 or less, and more preferably 0.880 g / cm 3 or less, and particularly preferably 0.875 g / cm 3 When the density of the olefin-based elastomer is within the above range, it is possible to provide a PSA composition that can achieve both resealability and easy opening properties.

[0020] The viscosity of the olefin elastomer at 190°C is preferably 1,500 mPa s to 6,500 mPa s, more preferably 2,000 mPa s to 6,000 mPa s, and even more preferably 3,000 mPa s to 5,000 mPa s. When the viscosity of the olefin elastomer is within the above range, the resulting composition can be suitably used as a hot-melt pressure-sensitive adhesive composition.

[0021] Any appropriate olefin-based elastomer can be used as the olefin-based elastomer. An α-olefin-based elastomer is preferably used. Specific examples of the α-olefin-based elastomer include at least one elastomer selected from ethylene-based elastomers, propylene-based elastomers, and 1-butene-based elastomers. The olefin-based elastomer may be a homopolymer of the above α-olefin-based elastomer, a copolymer of two or more α-olefin-based elastomers, or a copolymer of an α-olefin-based elastomer and another monomer component. A single olefin-based elastomer may be used, or two or more olefin-based elastomers may be used in combination. A propylene-based elastomer is preferred. The use of a propylene-based elastomer can improve the heat stability of the hot-melt pressure-sensitive adhesive composition. In this specification, the ethylene-based elastomer, propylene-based elastomer, and 1-butene-based elastomer refer to elastomers whose main components are ethylene, propylene, or 1-butene, respectively. In this specification, the term "main component" refers to the monomer component that accounts for the largest proportion of the components that make up the elastomer.

[0022] In one embodiment, the propylene-based elastomer comprises a copolymer of propylene and ethylene. By including a copolymer of propylene and ethylene, the initial adhesive strength of the pressure-sensitive adhesive layer formed from the hot-melt pressure-sensitive adhesive composition can be adjusted to an appropriate value. When a copolymer of propylene and ethylene is used as the propylene-based elastomer, the ethylene content in the propylene-based elastomer is preferably 5 wt% to 20 wt%, more preferably 7 wt% to 15 wt%. By ensuring that the ethylene content in the propylene-based elastomer is within the above range, a pressure-sensitive adhesive composition that can achieve both resealability and easy opening properties can be provided.

[0023] The softening point of the α-olefin elastomer is preferably less than 100° C., more preferably not more than 98° C., and even more preferably not more than 96° C. The softening point is, for example, not less than 30° C. When the softening point is within the above range, the resulting composition can be suitably used as a hot-melt pressure-sensitive adhesive composition.

[0024] A-3. Tackifier The hot melt pressure-sensitive adhesive composition contains 2 to 40% by weight of a tackifier. The hot melt pressure-sensitive adhesive composition preferably contains 30% by weight or less of a tackifier, more preferably 20% by weight or less, even more preferably 10% by weight or less, and particularly preferably 8% by weight or less. When the tackifier content is within the above range, a pressure-sensitive adhesive composition having sufficient initial adhesive strength and achieving both resealability and easy opening properties can be provided. When the tackifier content exceeds 40% by weight, adhesive residue on the adherend may occur. Furthermore, the adherend may be damaged during peeling, resulting in reduced easy opening properties. Furthermore, the hot melt pressure-sensitive adhesive composition preferably contains 4% by weight or more of a tackifier, more preferably 6% by weight or more. When the tackifier content is within the above range, a hot melt pressure-sensitive adhesive composition having appropriate adhesive strength to the adherend can be obtained.

[0025] Any appropriate resin can be used as the tackifier. Specific examples include natural resins such as terpene resins and rosin resins, as well as synthetic resins such as petroleum resins, hydrogenated petroleum resins, styrene resins, coumarone-indene resins, phenolic resins, and xylene resins. Examples of petroleum resins include aliphatic petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins of an alicyclic component and an aromatic component, and copolymerized petroleum resins of an alicyclic component and an aliphatic component. Hydrogenated petroleum resins are preferred. The use of hydrogenated petroleum resins improves compatibility with α-olefin elastomers, thereby improving the heat stability of the hot-melt adhesive composition. Only one tackifier may be used, or two or more tackifiers may be used in combination.

[0026] A-4.Oil The hot melt pressure-sensitive adhesive composition preferably further contains an oil. By including an oil, the wettability of the hot melt pressure-sensitive adhesive composition can be improved. Any appropriate oil can be used. Examples include process oil, naphthenic oil, paraffinic oil, and vulcanization oil. Preferably, paraffinic oil can be used. Only one type of oil can be used, or two or more types can be used in combination.

[0027] The oil can be used in any appropriate amount. The hot melt pressure-sensitive adhesive composition preferably contains 5 wt % to 30 wt % of oil. The hot melt pressure-sensitive adhesive composition more preferably contains 25 wt % or less of oil, and even more preferably contains 20 wt % or less of oil. If the oil content is high, adhesive residue may occur on the adherend. The hot melt pressure-sensitive adhesive composition more preferably contains 5 wt % or more of oil, even more preferably contains 10 wt % or more, and particularly preferably contains 15 wt % or more of oil. When the oil content is within the above range, a hot melt pressure-sensitive adhesive composition with excellent wettability can be obtained.

[0028] A-5. Other additives The hot-melt pressure-sensitive adhesive composition may further contain any other appropriate additives as needed. Examples include antioxidants, UV absorbers, light stabilizers, fluorescent agents, colorants, etc. These additives may be used alone or in combination of two or more. The other additives are used in any appropriate amount within the range in which the effects of the present invention can be obtained, and such that the total amount of the styrene-based elastomer, olefin-based elastomer, tackifier, and optional oil is 100% by weight.

[0029] In one embodiment, the hot melt PSA composition is substantially free of petrolatum. When the hot melt PSA composition contains petrolatum, the semi-fluid properties of petrolatum may reduce the workability of the preparation of the PSA composition. Furthermore, crystalline components contained in petrolatum may reduce the wettability and stability of the PSA composition. By being substantially free of petrolatum, the initial adhesive strength of the hot melt PSA composition can be stably adjusted to an appropriate value. Furthermore, the wettability of the hot melt PSA composition can be improved. Furthermore, the workability of the preparation of the hot melt PSA composition can be improved. In one embodiment, the hot melt PSA composition is substantially free of ethylene vinyl acetate. When the hot melt PSA composition contains ethylene vinyl acetate, the heat stability of the hot melt PSA may be reduced. Furthermore, the resulting hot melt PSA composition may have an odor characteristic of vinyl acetate. By being substantially free of ethylene vinyl acetate, the heat stability of the hot melt PSA composition is improved, and a hot melt PSA composition with little odor can be provided.

[0030] B. Adhesive tape One embodiment of the present invention provides a pressure-sensitive adhesive tape. This pressure-sensitive adhesive tape has a substrate and a pressure-sensitive adhesive layer. This pressure-sensitive adhesive layer is formed using the above-mentioned hot-melt pressure-sensitive adhesive composition. This hot-melt pressure-sensitive adhesive composition has sufficient initial adhesive strength and can achieve both resealability and easy opening. Therefore, it can also be suitably used as a resealing sealant for packaging materials for food products, sanitary products, detergents, etc.

[0031] The adhesive tape can be set to any appropriate thickness. For example, it is 20 μm to 200 μm, and preferably 20 μm to 130 μm. When the thickness of the adhesive tape is within the above range, it can be suitably used as a resealing seal material.

[0032] The adhesive layer may be formed over the entire surface of one side of the substrate, or may be formed over only a portion of the surface. Figures 1A and 1B are schematic cross-sectional views of an adhesive tape according to one embodiment of the present invention. The adhesive tape 100 shown in Figure 1A has a substrate 10, an undercoat layer 20, and an adhesive layer 30. In the illustrated example, the adhesive layer 30 is formed on one end of the substrate. The portion of the substrate 10 on which the undercoat layer 20 and the adhesive layer 30 are not formed can be used as a gripping portion when using the adhesive tape 100.

[0033] In one embodiment, a pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer formed from the hot melt pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer formed from another pressure-sensitive adhesive. The pressure-sensitive adhesive tape 101 shown in FIG. 1B has a substrate 10, an undercoat layer 20, a pressure-sensitive adhesive layer 31 formed from another pressure-sensitive adhesive, and a pressure-sensitive adhesive layer 32 formed from the hot melt pressure-sensitive adhesive composition. FIG. 2 is a schematic cross-sectional view showing a use mode of the pressure-sensitive adhesive tape according to the embodiment of the present invention. The illustrated example shows a mode in which the pressure-sensitive adhesive tape 101 is used as a resealing sealant for an adherend 200. In the illustrated example, the pressure-sensitive adhesive tape 101 is fixed to the adherend 200 by the pressure-sensitive adhesive layer 31 formed from another pressure-sensitive adhesive, and the pressure-sensitive adhesive layer 32 formed from the hot melt pressure-sensitive adhesive composition is adhered to the adherend 200 to reseal it. The hot melt pressure-sensitive adhesive composition can achieve both resealability and easy-openability. Therefore, when the adhesive tape 101 is used as a resealing sealant, it is possible to achieve both the ability to seal the adherend 200 and the ease of opening when opening the tape.

[0034] In this embodiment, the pressure-sensitive adhesive layer 31 is not peeled off from the adherend 200. Therefore, instead of the above-mentioned hot-melt pressure-sensitive adhesive composition, any appropriate pressure-sensitive adhesive with high adhesive strength (not easily openable) can be used. Examples of pressure-sensitive adhesives that form the pressure-sensitive adhesive layer 31 include rubber-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, polyvinyl alcohol-based pressure-sensitive adhesives, polyvinylpyrrolidone-based pressure-sensitive adhesives, polyacrylamide-based pressure-sensitive adhesives, and cellulose-based pressure-sensitive adhesives.

[0035] The adhesive tape preferably has an initial adhesive strength AF0 of 0.1 N / 10 mm to 5.0 N / 10 mm and an adhesive strength AF after storage of s The initial adhesive strength AF0 and adhesive strength after storage AF are 0.1N / 10mm to 5.0N / 10mm. s By ensuring that both are within the above ranges, a PSA composition can be obtained that has sufficient initial adhesive strength and is capable of achieving both resealability and easy opening. The initial adhesive strength AF0 is more preferably 0.1 N / 10 mm to 4.0 N / 10 mm, and even more preferably 0.1 N / 10 mm to 3.0 N / 10 mm. In addition, the adhesive strength after storage AF s is more preferably 0.1 N / 10 mm to 5.0 N / 10 mm, and even more preferably 0.1 N / 10 mm to 3.0 N / 10 mm. In this specification, the initial adhesive strength AF0 is the adhesive strength measured in a 180° peel test immediately after forming a pressure-sensitive adhesive layer on any substrate, and the adhesive strength after storage AF s refers to the adhesive strength measured in a 180° peel test after forming an adhesive layer on a substrate and storing it at 50°C for one week.

[0036] B-1.Adhesive layer The pressure-sensitive adhesive layers 30 and 32 are formed from the above-mentioned hot-melt pressure-sensitive adhesive composition. The thickness of the pressure-sensitive adhesive layer is 10 μm to 100 μm, preferably 10 μm to 80 μm, and more preferably 15 μm to 50 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, a pressure-sensitive adhesive tape that can achieve both resealability and easy opening can be obtained.

[0037] The pressure-sensitive adhesive layer can be formed by any appropriate method. For example, the pressure-sensitive adhesive layer may be formed by directly applying the hot-melt pressure-sensitive adhesive composition to a substrate, or the pressure-sensitive adhesive layer may be formed on a release-treated transfer film and then transferred to a substrate.

[0038] The hot melt pressure-sensitive adhesive composition can be applied to a substrate or a transfer film by any appropriate method, such as a roll coater, a knife coater, an air knife coater, a bar coater, a blade coater, a slot die coater, a lip coater, a gravure coater, or a spray coater.

[0039] B-2. Base material Any suitable substrate can be used, including, for example, polyolefin films such as polyethylene, polypropylene, and ethylene-propylene copolymers, polyester films such as polyethylene terephthalate, and plastic films such as polyvinyl chloride.

[0040] The plastic film may be a non-stretched film or a stretched (uniaxially or biaxially stretched) film. In one embodiment, the surface of the substrate on which the pressure-sensitive adhesive layer is to be formed may be subjected to a surface treatment such as application of a primer or corona discharge treatment. In addition, the surface of the substrate on which the pressure-sensitive adhesive layer is not to be formed may be subjected to a release treatment. By being subjected to a release treatment, it is possible to prevent the substrate and the pressure-sensitive adhesive layer from sticking together when the pressure-sensitive adhesive tapes are stacked, and it may be possible to store the tape in a roll form. In one embodiment, an olefin-based pressure-sensitive adhesive layer is formed as an undercoat layer 20 on the surface of the substrate on which the pressure-sensitive adhesive layer is to be formed. By laminating the substrate, the olefin-based pressure-sensitive adhesive layer, and the hot-melt pressure-sensitive adhesive composition in this order, anchor failure of the pressure-sensitive adhesive tape can be suppressed.

[0041] The thickness of the substrate can be set to any appropriate value, for example, 10 μm to 100 μm, preferably 30 μm to 90 μm, and even more preferably 50 μm to 80 μm.

[0042] In one embodiment, the pressure-sensitive adhesive tape can be suitably used as a resealing sealant. In one embodiment, the pressure-sensitive adhesive tape can be suitably used in packaging materials having a printed portion. Packaging materials may have a printed portion to display necessary information. When a packaging material has a printed portion, the adhesive strength of the pressure-sensitive adhesive tape may increase over time depending on the composition of the ink used for printing and the paint (e.g., lacquer) used to protect the printed surface, making it impossible to achieve easy peeling. This tendency may be more pronounced when a nitrocellulose-based lacquer is applied to the printed surface. The pressure-sensitive adhesive tape according to an embodiment of the present invention can achieve both resealability and easy opening, even when used in packaging materials having a printed surface to which a nitrocellulose-based lacquer is applied. [Example]

[0043] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation methods used in the examples are as follows. Unless otherwise specified, parts mean parts by weight, and % means % by weight.

[0044] [Examples 1 to 4 and Comparative Examples 1 to 3] The materials listed in Table 1 were mixed to prepare PSA 1 to 6 and primer layer 1. An unstretched PP film (thickness: 80 μm) with a release treatment applied to the side opposite to the PSA coated side was used as the substrate. Using a TrueCoat Slot applicator (manufactured by Nordson), the PSA forming the primer layer and the PSA layer were simultaneously laminated and coated onto the side of the substrate that had not been treated for release, yielding a PSA tape. The coating temperature was 160°C, and the line speed was 100 m / min. The thickness of the primer layer was 15 μm, and the thickness of the PSA layer was as listed in Table 2. The resulting PSA tapes were evaluated as follows.

[0045] [Table 1]

[0046] [evaluation] The tapes of the examples and comparative examples were cut to 10 mm wide to prepare samples. Commercially available packaging materials (printed films) were used as adherends. All printed films had a printed surface containing nitrocellulose lacquer. These printed films were attached to SUS plates using acrylic double-sided tape (Nitto Denko Corporation: No. 5000NS). The adhesive layer and printed film were attached to the film surface so that the bonded length of the adhesive layer and printed film was 25 mm, and the tape was pressed twice with a 2 kg load. For the initial evaluation, the tape was left at room temperature (23°C) for 30 minutes after bonding. For the storage evaluation, the tape was left in a thermostatic oven set at 50°C for one week and then left at room temperature for two hours. A peel test was then conducted at a peel angle of 180° and a peel rate of 305 mm / min to measure adhesive strength. Three samples were evaluated, and the average of the measurement results was recorded as adhesive strength. A Zwick-Roell Z0.5 tensile tester was used for the measurements. If the initial adhesive strength AF0 is between 0.1N / 10mm and 5.0N / 10mm, the initial adhesive strength is sufficient. The adhesive strength after leaving the film at 50°C for one week (adhesive strength after storage AF0) is s ) is 0.1N / 10mm to 5N / 10mm, both resealability and easy opening properties can be achieved.

[0047] [Table 2]

[0048] The pressure-sensitive adhesive tapes using the hot-melt pressure-sensitive adhesive compositions obtained in Examples 1 to 4 had sufficient initial adhesive strength, and excessive increase in adhesive strength was suppressed even after storage. The pressure-sensitive adhesive tape using the hot-melt pressure-sensitive adhesive composition of Comparative Example 1 had excessively high adhesive strength after storage, and the adherend (printed film) was deformed when peeled off. The pressure-sensitive adhesive tapes using the hot-melt pressure-sensitive adhesive compositions of Comparative Examples 2 and 3 could not be attached to the adherend either initially or after storage. [Industrial Applicability]

[0049] The hot melt pressure-sensitive adhesive composition according to the embodiment of the present invention and the pressure-sensitive adhesive tape using the hot melt pressure-sensitive adhesive composition are capable of achieving both resealability and easy opening. Therefore, they can be used as resealing sealants for various packaging materials such as food, daily necessities, and hygiene products. They can also be used as suitable resealing sealants for packaging materials with printed surfaces. [Explanation of symbols]

[0050] 100 adhesive tape 101 Adhesive Tape 10 Base material 20 Primer layer 30 adhesive layer 31 Adhesive layer 32 adhesive layer

Claims

1. The adhesive composition includes a styrene-based elastomer, an olefin-based elastomer, and a tackifier, 20% by weight to 75% by weight of the styrene-based elastomer, 2% by weight to 40% by weight of the olefin-based elastomer, The tackifier is contained in an amount of 2% by weight to 40% by weight, The hot melt pressure-sensitive adhesive composition, wherein the olefin elastomer is a propylene elastomer.

2. 2. The hot melt pressure-sensitive adhesive composition according to claim 1, comprising 5 to 40% by weight of the olefin elastomer.

3. The hot melt pressure sensitive adhesive composition according to claim 1 or 2, wherein the softening point of the propylene elastomer is lower than 100°C.

4. 4. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the styrene content of the styrene elastomer is 10% by weight to 25% by weight.

5. The hot melt pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the styrene elastomer comprises a styrene-isoprene block copolymer.

6. The hot melt pressure-sensitive adhesive composition according to claim 5, wherein the styrene-isoprene block copolymer comprises a diblock copolymer.

7. 7. The hot melt pressure-sensitive adhesive composition according to claim 6, wherein the styrene-isoprene block copolymer comprises 5% by weight to 70% by weight of a diblock copolymer.

8. The hot melt pressure-sensitive adhesive composition according to any one of claims 1 to 7, comprising 4 wt% to 30 wt% of the tackifier.

9. The hot melt pressure-sensitive adhesive composition according to any one of claims 1 to 8, wherein the tackifier is a hydrogenated petroleum resin.

10. The hot melt pressure-sensitive adhesive composition according to claim 1 , further comprising an oil.

11. The hot melt pressure-sensitive adhesive composition according to claim 10, comprising the oil in an amount of 5 to 30% by weight.

12. The hot melt pressure-sensitive adhesive composition according to any one of claims 1 to 11, which has a viscosity at 160°C of less than 50,000 mPa.s.

13. A pressure-sensitive adhesive comprising a substrate and the hot-melt pressure-sensitive adhesive composition according to any one of claims 1 to 12. an agent layer; The adhesive layer has a thickness of 10 μm to 100 μm.

14. Initial adhesive strength AF ０ The adhesive according to claim 13, wherein the adhesive strength after storage AFs is 0.1 N / 10 mm to 5.0 N / 10 mm. tape.

15. The pressure-sensitive adhesive tape according to claim 13 or 14, which is used as a resealing sealant.

16. The pressure-sensitive adhesive tape according to claim 13 , which is used for a packaging material having a printed portion.

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