AND PRESSURE-SENSITIVE ADHESIVE TAPE

The present disclosure relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive tape. More particularly, it relates to a self-adhesive pressure-sensitive adhesive and a self-adhesive pressure-sensitive adhesive tape.

BACKGROUND

Bag sealing tapes are widely used to bind and seal an opening of bag containing vegetables, fruits, bread, noodles, confectionery, processed food, and the like. The bag sealing tape is a so-called self-adhesive tape having a pressure-sensitive adhesive surface on one side, and is used to seal the bag opening by fastening both end portions of the pressure-sensitive adhesive surface together so as to be opposed to each other and binding the bag opening at portions of the pressure-sensitive adhesive surface other than the end portions (so-called butt seaming).

Patent Document 1 (Japanese Unexamined Patent Application Publication No. H02- 240185) describes“a base polymer consisting of a block copolymer of a mono-vinyl substituted aromatic compound and a conjugated diene compound is blended with an aliphatic petroleum resin having a molecular weight distribution (weight average molecular weight/number average molecular weight) of 1.9 or greater”.

Patent Document 2 (Japanese Unexamined Patent Application 2014-001312) describes“a self-adhesive pressure-sensitive adhesive tape” characterized by that“in the self-adhesive pressure-sensitive adhesive tape in which an adhesive is applied to one surface of a tape-shaped base material, an elastomer of the adhesive contains a mixture of l0wt% to 80wt% of styrene- isoprene-styrene block polymer including the styrene content from l4wt% or more to 19wt% or less and 20wt% to 90wt% of styrene-isoprene-styrene block polymer including the styrene content from 25wt% or more to 50wt% or less,” and has predetermined characteristics.

SUMMARY OF THE INVENTION

One of the required properties of the bag sealing tape is high self-adhesive strength (adhesive strength between pressure-sensitive adhesive surfaces). In addition, since the bag sealing tape is generally used together with a bag sealer, another required property of the sealing tape is that the tape does not break during the sealing operation using the bag sealer against the tensile stress applied to the tape in the bag sealer. As a result, sufficient tensile strength is required for the tape to withstand the sealing operation. On the other hand, it is desirable that the bag sealing tape has hand-tearability (it is possible to manually cut the tape). The bag sealing tape made of a paper base material has hand- tearability, but has insufficient strength under wet conditions and has low design as well.

Although the bag sealing tape made of a film base material having such hand-tearability can be obtained, for example, by introducing fine scratches into the side surface of the film base material when the tape is slit the tape, the tensile strength of the tape is greatly reduced. When the bag sealing tape made of the film base material having such hand-tearability is used in a bag sealer, the pressure-sensitive adhesive surface of the tape may contact any component inside the bag sealer and adhere to the part to be easily broken. As such, it is desirable that the pressure- sensitive adhesive of the bag sealing tape does not exhibit excessively high adhesive strength onto surfaces of other materials such as the components in the bag sealer and the like.

The present disclosure provides a pressure-sensitive adhesive having high self-adhesive strength while suppressing adhesiveness to other material surfaces, and a pressure-sensitive adhesive tape including such pressure-sensitive adhesive.

According to one embodiment, a pressure-sensitive adhesive includes a styrene-isoprene block copolymer, an adhesion-imparting agent containing an aliphatic compound, and a terpene phenol resin, and contains 2.0 parts by mass to 10 parts by mass of a terpene phenol resin based on 100 parts by mass of the pressure-sensitive adhesive.

According to another embodiment, a pressure-sensitive adhesive tape includes a polymer film base material and a pressure-sensitive adhesive layer disposed on the polymer film base material, the pressure-sensitive adhesive layer including the pressure-sensitive adhesive.

According to yet another embodiment, a pressure-sensitive adhesive tape includes a polymer film base material and a pressure-sensitive adhesive layer disposed on the polymer film base material, the pressure-sensitive layer includes a styrene-isoprene block copolymer, an adhesion imparting agent including an aliphatic compound, and a terpene phenol resin, a self- adhesive strength measured as a T-peel strength when pressure-sensitive adhesive surfaces are bonded to each other is 4.0N/cm or greater, an adhesive strength measured as a 180-degree peeling strength with respect to the surface of an acrylonitrile-styrene copolymer is 3.5N/cm or less, and a tensile strength is in a range from 20 to 40N/cm.

The present disclosure can provide a pressure-sensitive adhesive having high self- adhesive strength while suppressing adhesiveness to other material surfaces, and a pressure- sensitive adhesive tape including such pressure-sensitive adhesive.

The above descriptions should not be construed that all embodiments of the present invention and all advantages of the present invention are disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of a pressure-sensitive adhesive tape according to an embodiment.

FIGS. 2 are views illustrating states in which a plastic bag is being opened, FIG. 2(a) illustrates the state where the pressure-sensitive adhesive tape wrapped around a plastic bag is pinched with fingers, FIG. 2(b) illustrates the state where pressure-sensitive adhesive layers of the pressure-sensitive adhesive tape, which are adhered to each other, are pinched with the thumb and the index finger, to break the tape by application of a shear force, and FIG. 2(c) indicates the state where the broken pressure-sensitive adhesive tape is being removed from the plastic bag.

DESCRIPTION OF EMBODIMENTS

Although representative embodiments of the present invention will now be described in more detail for the purpose of illustration with reference to the Figure, the present invention is not limited to these embodiments. The elements having similar reference numerals in different drawings indicate similar or corresponding elements. The characteristic values referred to in this disclosure (specifically, adhesive strength, T-peel strength, tensile strength, and elongation to break) are values measured by the method described in the Examples section of the present disclosure or the equivalent methods understood by those skilled in the art.

The term“pressure-sensitive adhesiveness” as used herein means properties of a material or a composition having permanently adhesiveness within a range of the operation temperature, for example, within a range from 0 °C or more to 0°C or less, being capable of adhering to various surfaces with a small pressure without changing the phase (from liquid to solid).

The pressure-sensitive adhesive according to an embodiment includes a styrene-isoprene block copolymer (SIS), an adhesion imparting agent including an aliphatic compound, and a terpene phenol resin.

The styrene-isoprene block copolymer has a high cohesive strength suitable for a bonding material by physical crosslinking of the styrene block, and the physical crosslinking can be suitably applied to a hot melt pressure-sensitive adhesive for plasticization and fluidization by heating. Examples of the styrene-isoprene block copolymer include Quintac™ (trademark) 3620, Quintac™ 3421 (both manufactured by Zeon Corporation), and Kraton™ D 1107 (manufactured by Kraton Polymer Japan Co., Ltd.).

The styrene-isoprene block copolymer is generally a mixture of a linear triblock body and a diblock body (styrene block-isoprene block). The styrene-isoprene block copolymer may include an A-B-A-B-A type multi-block or a radial block copolymer. In one embodiment, the content of the diblock body in the styrene-isoprene block copolymer is less than approximately 30mass%, approximately 28mass% or less, or approximately 26mass% or less. By setting the content of the diblock body to be less than approximately 30mass%, adhesiveness to other material surfaces can be suppressed. The content of the diblock body in the styrene-isoprene block copolymer may be approximately 0.5mass% or greater, approximately lmass% or greater, or approximately 5mass% or greater, and the styrene-isoprene block copolymer may not include the diblock body.

In an embodiment, the styrene content in the styrene-isoprene block copolymer is approximately 8mass% or greater, approximately l0mass% or greater, or approximately l2mass% or greater, and approximately 30mass% or less, approximately 25mass% or less, or approximately 20mass% or less. By setting the styrene content to be approximately 30mass% or less, advantageous adhesive strength can be ensured as a pressure-sensitive adhesive. By setting the styrene content to be approximately 8 mass or greater, the cohesive strength of the pressure- sensitive adhesive can be increased, such that at removal of the pressure-sensitive adhesive tape from a bag that is an adhered object, and during the sealing operation using a bag sealer, remaining glue on the bag or components of the bag sealer can be reduced or prevented.

Furthermore, by setting the styrene content to approximately 8mass% or greater, the styrene- isoprene block copolymer can be supplied in a pellet form to increase the handleability of the styrene-isoprene block copolymer during production of the pressure-sensitive adhesive.

The content of the styrene-isoprene block copolymer can be approximately 45 parts by mass or greater, approximately 50 parts by mass or greater, or approximately 55 parts by mass or greater, and approximately 75 parts by mass or less, approximately 70 parts by mass or less, or approximately 65 parts by mass or less, based on 100 parts by mass of the pressure-sensitive adhesive. By setting the content of the styrene-isoprene block copolymer to be approximately 45 parts by mass or greater based on 100 parts by mass of the pressure-sensitive adhesive, it is possible to prevent the adhesive strength of the pressure-sensitive adhesive from being excessively high. By setting the content of the styrene-isoprene block copolymer to be approximately 75 parts by mass or less based on 100 parts by mass of the pressure-sensitive adhesive, it is possible to ensure initial stickiness (tackiness) of the pressure-sensitive adhesive under low-temperatures.

The adhesion imparting agent includes an aliphatic compound. In the present disclosure, the aliphatic compound encompasses alicyclic compounds, and also encompasses homopolymers and copolymers containing polymerized units derived from aliphatic compounds. The adhesion imparting agent including the aliphatic compound has excellent compatibility with the isoprene phase of the styrene-isoprene block copolymer, and can impart stickiness and adhesiveness to the pressure-sensitive adhesive. The adhesion imparting agent may be a blend of a plurality of aliphatic compounds.

The copolymer including a polymerized unit derived from the aliphatic compound generally contains the polymerized unit derived from the aliphatic compound as a main component. In an embodiment, the copolymer including the polymerized unit derived from the aliphatic compound contains the polymerized unit derived from the aliphatic compound by 50% or more, approximately 60% or more, approximately 70 % or more, 100% or less, approximately 95% or less, or approximately 90% or less in mole fraction.

Examples of the aliphatic compound include aliphatic hydrocarbon resins. Examples of aliphatic hydrocarbon resins are C5 petroleum resins such as Quintone™ Ml 00 series (Zeon Corporation), Piccopale™ (Trademark) series (Eastman Chemical), ESCOREZ™ series (Exxon Mobil Corporation), and WingTack™ (Kratarbury Co., Ltd.), and C5/C9 petroleum resins such as the Quintone™ G115 (Zeon Corporation) and Petrotuck™ series (Tosoh Corporation).

Examples of other aliphatic compounds include alicyclic hydrocarbon resins, rosin resins, hydrogenated rosin resins, terpene resins, and the like. Examples of the alicyclic hydrocarbon resins include C9 hydrogenated petroleum resins such as Arcon™ P series and Arcon™ M series (both are manufactured by Arakawa Chemical Industries, Ltd.). Examples of the rosin-based resins include Ester Gum™ AA, Ester Gum™ AT (Arakawa Chemical Industries, Ltd.), and Haliesters™ TF (Harima Chemicals Group, Inc.). Examples of the hydrogenated rosin-based resins include Ester Gum™ H (Arakawa Chemical Industries, Ltd ), and the like. Examples of the terpene resins include YS resin PX series (Yasuhara Chemical Co., Ltd.), and the like.

In an embodiment, the adhesion imparting agent is selected from the group consisting of the aliphatic hydrocarbon resins, the alicyclic hydrocarbon resins, the rosin-based resins, the hydrogenated rosin-based resins, and the terpene resins.

In another embodiment, the adhesion imparting agent is selected from the aliphatic hydrocarbon resins and is advantageously selected from the C5 based petroleum resins, the C5/C9 petroleum resins, and combinations thereof. The aliphatic hydrocarbon resins, especially the C5 based petroleum resins and the C5/C9 petroleum resins, can impart high self- adhesiveness to the pressure-sensitive adhesive.

In an embodiment, the softening point of the adhesion imparting agent is approximately 85°C or higher, approximately 90°C or higher, or approximately 95°C or higher, and

approximately 1 25°C or lower, approximately l20°C or lower, or approximately H5°C or lower. By setting the softening point of the adhesion imparting agent to approximately 85°C or higher, it is possible to ensure initial adhesiveness of the pressure-sensitive adhesive in low- temperature environments. By setting the softening point of the adhesion imparting agent to approximately l25°C or lower, it is possible to suppress the pressure-sensitive adhesive from flowing under high temperatures and maintain the adhesive strength of the pressure-sensitive adhesive.

The content of the adhesion imparting agent may be set to be approximately 20 parts by mass or more, approximately 25 parts by mass or more, or approximately 30 parts by mass or more, and approximately 50 parts by mass or less, approximately 45 parts by mass or less, or approximately 40 parts by mass or less based on 100 parts by mass of the pressure-sensitive adhesive. By setting the content of the adhesion imparting agent to approximately 20 parts by mass or greater based on 100 parts by mass of the pressure-sensitive adhesive, high self- adhesiveness can be imparted to the pressure-sensitive adhesive. By setting the content of the adhesion imparting agent to approximately 50 parts by mass or less based on 100 parts by mass of the pressure-sensitive adhesive, it is possible to ensure initial adhesiveness of the pressure- sensitive adhesive under low -temperature environment.

The terpene phenolic resin is a component that contributes to both the self-adhesiveness of the pressure-sensitive adhesive and the suppressed adhesiveness to other surfaces. Without being bound by any theory, because the terpene phenol resin has a hydroxyl group, it has a relatively low compatibility with the styrene-isoprene block copolymer, and at least partially separates out on the pressure-sensitive adhesive surface. This is believed to reduce adhesiveness to other material surfaces, particularly, initial stickiness. On the other hand, when the pressure- sensitive adhesive surfaces are brought into contact with each other, by flowing and diffusing the pressure-sensitive adhesive at the interface, the precipitate of the terpene phenol resin can be eliminated from the interface to acquire self-adhesiveness. In addition, when the pressure- sensitive adhesive surfaces are to be peeled from each other, the interface between the precipitate of the terpene phenol resin and a matrix portion formed of the styrene-isoprene block copolymer and the adhesion imparting agent is disrupted, thereby dissipating peeling energy, that is, acquiring the peeling property between the pressure-sensitive adhesive surfaces. The terpene phenolic resin that is present within the pressure-sensitive adhesive or the pressure-sensitive adhesive layer function as the adhesion imparting agent, and contributes to the sticking strength and adhesive strength of the pressure-sensitive adhesive or the pressure-sensitive adhesive layer.

The terpene phenolic resin may be a blend of a plurality of terpene phenolic resins having different hydroxyl values. In an embodiment, the terpene phenolic resin consists of one type of terpene phenolic resin.

In an embodiment, the softening point of the terpene phenolic resin is approximately l00°C or higher, approximately 110°C or higher, or approximately 120°C or higher, and approximately l45°C or lower, approximately l40°C or lower, or approximately l35°C or lower. By setting the softening point of the terpene phenol resin to be approximately l00°C or higher, it is possible to prevent a significant decrease in self-adhesive strength caused by the low molecular weight component of the terpene phenol resin. By setting the softening point of the terpene phenolic resin to be approximately l45°C or lower, the incompatible state of the terpene phenol resin to the extent that the overall phase of the pressure-sensitive adhesive becomes non- uniform can be avoided.

In an embodiment, the hydroxyl value of the terpene phenol resin is approximately l20mgKOH/g or more, approximately l30mgKOH/g or more, or approximately l50mgKOH/g or more, and approximately 240mgKOH/g or less, approximately 230mgKOH/g or less, or approximately 220mgKOH/g or less. By setting the hydroxyl value of the terpene phenol resin to be approximately l20mg KOH/g or more, precipitation of the terpene phenol resin can be induced. By setting the hydroxyl value of the terpene phenol resin to be approximately 240mg KOH/g or less, the incompatible state of the terpene phenol resin to the extent that the overall phase of the pressure-sensitive adhesive becomes non-uniform can be avoided.

The content of the terpene phenol resin may be set to be approximately 2.0 parts by mass or more, approximately 2.2 parts by mass or more, or approximately 2.5 parts by mass or more, and approximately 10 parts by mass or less, approximately 8.5 parts by mass or less, or approximately 7.5 parts by mass or less based on 100 parts by mass of the pressure-sensitive adhesive. By setting the content of the terpene phenol resin to be approximately 2.0 parts by mass or more based on 100 parts by mass of the pressure-sensitive adhesive, high self-adhesion can be imparted to the pressure-sensitive adhesive. By setting the content of the terpene phenol resin to be approximately 10 parts by mass or less based on 100 parts by mass of the pressure- sensitive adhesive, the incompatible state of the terpene phenol resin to the extent that the overall phase of the pressure-sensitive adhesive becomes non-uniform can be avoided.

Generally, there is a trade-off relationship between the hydroxyl value and the content of the terpene phenol resin in terms of compatibility with the styrene-isoprene block copolymer.

For example, as the hydroxyl value of the terpene phenol resin is higher, the content thereof becomes smaller, and as the hydroxyl value of the terpene phenol resin is lower, the content thereof becomes larger. Therefore, the hydroxyl value and the content of the terpene phenol resin are appropriately adjusted so as to acquire desired self-adhesiveness and adhesiveness to other material surfaces.

The pressure-sensitive adhesive may include other polymers so as not to impair the effects of the present disclosure. Examples of such polymers include diene-containing rubbers such as natural rubber, isoprene rubber, and isobutylene rubber, styrene-butadiene rubber (SBR), chloroprene rubber, butyl rubber, butadiene-acrylonitrile copolymer, thermoplastic elastomer, styrene-butadiene block copolymer, etylene-propylene-diene copolymer, poly(alpha-olefms), amorphous polyolefins, silicones, ethylene-containing copolymers such as ethylene-vinyl acetate copolymers, ethylene ethyl acrylate copolymers, and ethylene ethyl methacrylate copolymers; polyurethanes; polyamides; epoxy resins; polyvinylpyrrolidone and vinylpyrrolidone

copolymers; polyesters; and the like.

The pressure-sensitive adhesive may contain additives such as antioxidants, thermal stabilizers, UV absorbers, fillers, plasticizers, and mineral oils, to the extent that the effects of the present disclosure are not impaired. The pressure-sensitive adhesive may be crosslinked using a crosslinking agent such as a sulfur compound, a thermally reactive phenol resin, or a polyisocyanate.

The pressure-sensitive adhesive may be a solvent-based adhesive including a solvent such as pentane, hexane, heptane, cyclohexane, acetone, ethyl methyl ketone, isobutyl methyl ketone, toluene, and xylene, a water-based emulsion adhesive, or a solventless adhesive. In an embodiment, the pressure-sensitive adhesive is a solvent-free hot melt adhesive.

The pressure-sensitive adhesive tape according to an embodiment has a polymer film base material and a pressure-sensitive adhesive layer disposed on the polymer film base material.

As the polymer film base material, a biaxially oriented polypropylene (OPP) film, a polyethylene terephthalate (PET) film, a polyvinyl chloride (PVC) film, a polyethylene (PE) film, an ethylene-vinyl acetate copolymer (EVA) film, or the like can be used. The polymer film base material may be a polymer film containing a plurality of components such as polypropylene and polyethylene. A pressure-sensitive adhesive tape having hand-tearability may be produced using an OPP film biaxially stretched at different stretching factors so as to have anisotropy. In an embodiment, the polymer film base material is a slit base material.

The polymer film base material is not limited to a strip shape (tape shape), and may be a sheet having a smaller thickness as compared to the length thereof.

The polymer film base material may have a release treatment layer on a surface opposite to the surface on which the pressure-sensitive adhesive layer is disposed. When the pressure- sensitive adhesive tape is a roll tape, the release treatment layer can smoothly draw the tape during use. The release treatment layer may be, for example, a coating layer including a

(meth)acrylic resin having a long chain alkyl group, a fluorine-based resin, a silicone, or the like. In bag sealing tape application, a coating layer made of a (meth)acrylic resin having a long chain alkyl group is advantageously used it can impart the excellent release property while avoiding a decrease in hand-tearability due to excessive slip.

The surface on which the pressure-sensitive adhesive layer of the polymer film base material is disposed may be subjected to surface treatment such as corona treatment, flame treatment, ultraviolet treatment, primer treatment, matte treatment, or the like to improve adhesion between the polymer film base material and the pressure-sensitive adhesive layer.

A printed layer including letters, symbols, patterns, or the like may be provided on the polymer film base material to impart a design or display function to the pressure-sensitive adhesive tape.

The polymer base material may have a thickness of approximately 10pm or more, approximately 20pm or more, or approximately 30pm or more, and approximately 200pm or less, approximately l50pm or less, or approximately l20pm or less.

The pressure-sensitive adhesive layer can be formed on the polymer film base material by any known method using the pressure-sensitive adhesive described above. For example, one surface of the polymer film base material may be coated with the pressure-sensitive adhesive using a gravure coater, a roll coater, reverse coater, a doctor blade coater, a bar coater, a knife coater, a die coater, a hot melt coater or the like, and as necessary, further cured by heating or radiation exposure to form the pressure-sensitive adhesive layer on the polymer film base material. As a result, the pressure-sensitive adhesive tape can be manufactured.

Generally, the pressure-sensitive adhesive layer has a thickness of is approximately 5 pm or more, approximately lOpm or more, or approximately 20pm or more, and approximately lOOpm or less, approximately 80mm or less, or approximately 50pm or less.

The width of the pressure-sensitive adhesive tape can be appropriately determined according to the application. In the bag sealing tape application, the width of the pressure- sensitive adhesive tape can be approximately 6mm or more or approximately 8mm or more in view of good sealing performance, and can be approximately l5mm or less or approximately l2mm or less in terms of good hand-tearability.

By slitting the wide pressure-sensitive adhesive tape with a score blade or the like, fine scratches can be formed on the side surface of the pressure-sensitive adhesive tape to impart hand-tearability to the pressure-sensitive adhesive tape. In an embodiment, the pressure-sensitive adhesive tape is slit.

FIG. 1 is a schematic cross sectional view of the pressure-sensitive adhesive tape according to an embodiment. A pressure-sensitive adhesive tape 10 has a polymer film base material 12, a pressure-sensitive adhesive layer 14 disposed on the polymer film base material 12, and an optional release treatment layer 16 on a surface of the polymer film base material opposite to the surface on which the pres sure- sensitive adhesive layer 14 of the polymer film base material 12 is disposed.

In an embodiment, the self-adhesive strength of the pressure-sensitive adhesive tape is approximately 4.0N/cm or more. The self-adhesive strength is measured as the T-peel strength when the pressure-sensitive adhesive surfaces are adhered to each other. The self-adhesive strength is an indicator of the adhesive durability of a region where the pressure-sensitive adhesive layers are fixedly adhered to each other (typically, a butt seaming region of tape end portions). If the adhesive durability is good, the sealing performance of the bag sealing tape is good. In some embodiments, the self-adhesive strength is approximately 5.0N/cm or more or approximately 6.0N/cm or more. The self-adhesive strength of the pressure-sensitive adhesive tape may be approximately l5N/cm or less, or approximately l2N/cm or less, in view of handleability during production and use of the pressure-sensitive adhesive tape.

In an embodiment, the adhesive strength measured as the 180-degree peeling strength of the pressure-sensitive adhesive tape with respect to the surface of an acrylonitrile- styrene copolymer is approximately 3.5N/cm or less. The adhesive strength to the surface of the acrylonitrile-styrene copolymer is representative value of the adhesive strength to other material surfaces. Due to the adhesive strength to the surface of the acrylonitrile styrene copolymer being approximately 3.5N/cm or less, in the bag sealing tape application requiring hand tearability, the adhesion of the pressure-sensitive adhesive tape to other material surfaces such as components inside the bag sealer can be suppressed or prevented to prevent or suppress tearing of the tape during the sealing operation. In some embodiments, the adhesive strength of the pressure- sensitive adhesive tape to the surface of the acrylonitrile-styrene copolymer is approximately 3.2N/cm or less, or approximately 3.0N/cm or less. The adhesive strength of the pressure- sensitive adhesive tape to the surface of the acrylonitrile-styrene copolymer may be

approximately 2.0N/cm or more, or approximately 2.5N/cm or more, in order to fix the pressure- sensitive adhesive tape to an adhered object such as a bag, container, or the like.

In an embodiment, the tensile strength of the pressure-sensitive adhesive tape is approximately 20N/cm or more and approximately 40N/cm or less. In some embodiments, the tensile strength of the pressure-sensitive adhesive tape is approximately 22N/cm or more or approximately 25N/cm or more and approximately 38N/cm or less or approximately 35N/cm or less. By setting the tensile strength of the pressure-sensitive adhesive tape to be approximately 20N/cm or more, it is possible to ensure the necessary strength for the pressure-sensitive adhesive tape used as the bag sealing tape during operation and binding. By setting the tensile strength of the pressure-sensitive adhesive tape to be approximately 40N/cm or less, good hand- tearability can be imparted to the bag sealing tape, for example. In the present disclosure, the tensile strength means the maximum strength measured during the tensile test.

In an embodiment, the elongation at break of the pressure-sensitive adhesive tape is approximately 70% or less, approximately 60% or less, or approximately 50% or less. By setting the breaking elongation of the pressure-sensitive adhesive tape to be approximately 70% or less, it is possible to avoid a decrease in hand-tearability of the pressure-sensitive adhesive tape used as the bag sealing tape, due to excessive stretch of the bag sealing tape. In one embodiment, the elongation at break of the pressure-sensitive adhesive tape is approximately 10% or more, approximately 15% or more, or approximately 20% or more. By setting the elongation at break of the pressure-sensitive adhesive tape to be approximately 10% or more, handleability of the pressure-sensitive adhesive tape during production and use can be improved.

The pressure-sensitive adhesive and the pressure-sensitive adhesive tape of the present disclosure can be used in a variety of applications requiring self-adhesiveness, for example, binding tapes such as a bag sealing tape and a code, and W (omega) fastening tape for securing a catheter or the like to the skin without contacting the skin. In an embodiment, the pressure- sensitive adhesive tape is a bag sealing tape.

EXAMPLES

Although the illustrative embodiments of the present disclosure will be exemplified in the following Examples, the present invention is not limited to these embodiments. All parts and percents are based on the mass, unless otherwise stated. Various tests were performed in accordance with JIS Z 0237: 2000 in an environment at a temperature of 23 °C and a relative humidity of 50%.

The reagents and materials used in the Examples are shown in Table 1. Table 1

1) The hydroxyl value is determined in accordance with JIS K0070

Examples 1 to 9 and Comparative Example 1 to 9

The ingredients listed in Table 2 were dissolved in a mixed solvent (toluene 12 isopropanol = 80/20 (w/w)) to acquire a solution containing a solid content of 50%. The solution was applied to 3M® OPP film having a thickness of 30pm with a knife coater, and dried in an oven to form a pressure-sensitive adhesive layer having a thickness of 20pm. The pressure- sensitive adhesive layer was covered with a silicone release treated PET film to form a tape. Adhesive strength to surface of acrylonitrile- styrene copolymer

The tape sample was cut to have a width of lOmm and length of l50mm. The acrylonitrile-styrene copolymer (AS) panel was washed with a heptane/2 -propanol mixture solvent. The silicone release treated PET film was removed from the tape, the tape was placed on an AS panel. Then, a rubber roller having a mass of 2kg was reciprocated once on the AS panel. Within one minute, the tape was peeled using a tensile tester Autograph AG-X (Shimadzu Corporation (Kyoto-shi, Kyoto-fu, Japan)) with 180 degrees at a peeling speed of

300mm/minute. An average value (N/cm) of the adhesive strength measured twice is as adhesive strength in Table 2. Self-adhesive strength

The tape sample was cut to have a width of lOmm and length of l50mm. The silicone release treated PET film was removed from the tape, and the tape was folded so that the pressure-sensitive adhesive surfaces faced each other. A rubber roller having a mass of 2kg was reciprocated once over the folded tape such that the pressure-sensitive adhesive surfaces were pressed against each other. After the tape was left to stand for 20 minutes, both ends of the tape were gripped using a tensile tester autograph AG-X (Shimadzu Corporation (Kyoto-shi, Kyoto- fu, Japan)), and T-peeled at a peeling rate of 300mm/minute. The average value (N/cm) of the T- peel strength measured twice is shown in Table 2 as the self-adhesive strength.

Table 2 (the formulation is based on parts by mass)

Examples 10 to 15 Comparative Example 10

A tape was produced using a pressure-sensitive adhesive in Example 2 or

Comparative Example 8 and various polymer film base materials. The tape was slit to have a width of 9mm using a score blade or a razor blade.

Tensile Strength and Elongation at Break

The tensile strength and elongation at break of the tape were measured in accordance with JIS Z 0237:2009. The tensile strength was converted to a value measured for the tape of 9mm width into a value for the tape of 1 cm width.

Hand Tearabilitv

The hand-tearability refers to the ease of tearing and opening the pressure-sensitive adhesive tape wrapped around a plastic bag while gripping the tape with fingers.

Specifically, as illustrated in FIG. 2(a), first, a region where the pressure-sensitive adhesive layers of a pressure-sensitive adhesive tape X wrapped around a plastic bag Y is pinched with a thumb FI and an index finger F2. Next, as illustrated in FIG. 2(b), the pressure-sensitive adhesive tape X is pulled and broken while creating a trigger of break with the thumb Fl . Further, as illustrated in FIG. 2(c), when the pressure-sensitive adhesive tape X is broken, the pressure-sensitive adhesive tape X is pulled as it is and peeled from the plastic bag to open the plastic bag Y. In FIG. 2(b) and FIG. 2(c), only one pressure-sensitive adhesive tape is broken, but two pressure-sensitive adhesive tapes may be broken to open the plastic bag Y. According to the procedure described above, if the pressure-sensitive adhesive tape X broke and the plastic bag Y was easily opened, it was determined as“good”, and if the pressure-sensitive adhesive tape X did not break and was not easily opened, it was determined as“bad”.

Dispensability

An opening of the plastic bag mouth was closed with a pressure-sensitive adhesive tape having a width of 9mm using a bag sealer (a sealer dedicated to paper bag sealing, manufacturing Okamoto Industries Inc, Bunkyo-ku, Tokyo, Japan). If the opening of the plastic bag could be closed without any problem, it was determined as“good”, and if the base material of the pressure-sensitive adhesive tape broke and the opening of the bag could not be closed, it was determined as“bad”.

Evaluation results are shown in Table 3.

Table 3