JP6434790B2 - Adhesive tape - Google Patents

Description

  The present invention relates to an adhesive tape using a stretched polyolefin as a substrate.

  Adhesive tapes such as cellophane tape are used for light packaging in supermarkets and convenience stores. However, since the cellophane base material is expensive and has high hygroscopicity, the base material absorbs and swells when stored in a roll shape around a cylindrical winding core, and the so-called bamboo shoot-like displacement occurs. There was a problem that it would occur. Therefore, development of an adhesive tape using polyolefin as a tape base material instead of cellophane is underway.

  On the other hand, these adhesive tapes are often used in a state set in a tape cutter. In that case, after pulling out a required amount of the adhesive tape, the adhesive tape is cut with a cutter blade provided in the tape cutter. At that time, the tape is cut by temporarily sticking the adhesive tape to the cutter blade and then pulling the adhesive tape. However, when an adhesive tape using polyolefin as a base material is to be cut, there is a problem that when the adhesive tape is pulled on the cutter blade, the tape stretches and is difficult to cut.

Patent 4680388

  This invention makes it a subject to provide the adhesive tape which has a fixed tensile strength and is easy to cut | disconnect with the cutter blade etc. which were provided to the tape cutter.

  Under the above circumstances, as a result of intensive studies, the present inventor has found that the above problem can be solved by adjusting the elongation at break of the stretched polyolefin used as the base material of the adhesive tape to a certain range. The present inventor completed the present invention as a result of various studies based on the above-described novel findings.

Accordingly, the present invention provides the following sections:
Item 1. A pressure-sensitive adhesive tape obtained by laminating a pressure-sensitive adhesive layer on a stretched polyolefin base material, wherein the base material has a breaking elongation of 1 to 6%.

  Item 2. Item 2. The pressure-sensitive adhesive tape according to Item 1, wherein the substrate is obtained by irradiating a stretched polyolefin substrate with an electron beam of 20 to 280 KGy.

  Item 3. Item 3. The pressure-sensitive adhesive tape according to Item 2, wherein the substrate is obtained by heating a stretched polyolefin substrate irradiated with the electron beam at a temperature of 80 ° C to 140 ° C for 20 seconds to 300 seconds.

  Item 4. A method for producing an adhesive tape, comprising a step of irradiating a polyolefin substrate with an electron beam.

  Item 5. Item 5. The method for producing an adhesive tape according to Item 4, further comprising a step of heating the polyolefin substrate irradiated with the electron beam at a temperature of 80 ° C or higher for 20 seconds to 300 seconds.

  Item 6. Item 6. The method for producing a pressure-sensitive adhesive tape according to Item 4 or 5, further comprising a step of laminating a pressure-sensitive adhesive layer on the polyolefin substrate irradiated with the electron beam.

  Item 7. The method to improve the cut property in the tape cutter of an adhesive tape including the process of irradiating an electron beam to a polyolefin base material.

  Item 8. Item 8. The method for improving the cutting property of the pressure-sensitive adhesive tape with a tape cutter according to Item 7, further comprising heating the stretched polyolefin substrate irradiated with the electron beam at a temperature of 80C to 140C for 20 seconds to 300 seconds.

  The pressure-sensitive adhesive tape of the present invention has a certain tensile strength, and when the pressure-sensitive adhesive tape is cut with a cutter blade or the like provided for the tape cutter, it is easy to cut because the elongation of the tape is suppressed. Conventionally, the pressure-sensitive adhesive tape of the present invention is very useful because it has only had a very high elongation at break as a pressure-sensitive adhesive tape using a polyolefin substrate. Moreover, since the adhesive tape of this invention has suppressed the expansion | extension of a tape, not only the case where this is mounted | worn to a tape cutter but the cutting | disconnection of a tape becomes easy also in embodiment which attaches a metal cutter blade.

The outline of the measuring method of breaking elongation in an example of this application is shown.

Adhesive Tape The present invention provides an adhesive tape obtained by laminating an adhesive layer on a stretched polyolefin substrate, wherein the elongation at break of the substrate is 1 to 6%.

Examples of the stretched polyolefin include polyethylene, polypropylene, EVA, EMMA, copolymers thereof, and the like, and polypropylene is preferable.
These polyolefins may be isotactic, syndiotactic or atactic. These polyolefins are preferably those that have been stretched in at least one direction (particularly biaxially stretched polyolefins). When polyolefin that is not stretched is used as a tape base material, it may be easily stretched and difficult to transport in the electron beam irradiation process. Moreover, when the irradiated base material is adhesively processed into a tape and used with a tape cutter, the tape tends to be stretched, and the suitability of the cutter may deteriorate.
In addition, these stretched polyolefins may be subjected to corona treatment in order to improve the adhesion between the adhesive layer and the base material layer in the configuration of the tape.

  The thickness of the tape substrate is not particularly limited as long as the above breaking elongation can be obtained, but it can be appropriately set within the range of preferably 15 to 70 μm, more preferably 25 to 60 μm, and even more preferably 30 to 50 μm. The width of the tape base material is not particularly limited, but can be appropriately set within a range of preferably 5 to 100 mm, more preferably 10 to 50 mm.

Although it does not specifically limit as irradiation amount of an electron beam, 20 kGy or more is preferable, 30 kGy or more is more preferable, and 50 kGy or more is further more preferable. Moreover, 280 kGy or less is preferable, 250 kGy or less is more preferable, and 200 kGy or less is more preferable.
For example, in a preferred embodiment, the thickness of the tape base material can be 25 to 45 μm, and the electron beam irradiation amount can be 20 to 100 kGy, preferably 40 to 60 kGy.
Moreover, in other preferable embodiment, the thickness of a tape base material can be 35-55 micrometers, and the irradiation amount of an electron beam can be 100-280 kGy, Preferably it can be 120-250 kGy.

In the present invention, the stretched polyolefin base material includes those subjected to the electron beam irradiation and heat treatment. In the embodiment of the present invention in which the stretched polyolefin substrate is irradiated with an electron beam, residual radicals may be generated in the stretched polyolefin substrate by the electron beam irradiation. When the residual radical is generated, the molecular chain of the resin contained in the polyolefin base material may be cut with time due to the residual radical, and the mechanical strength of the polyolefin base material may decrease with time. The heat treatment suppresses a decrease in mechanical strength of the stretched polyolefin base material over time. Therefore, the pressure-sensitive adhesive tape of the present invention in this embodiment is preferable because it can be easily cut while having a certain tensile strength, and the mechanical strength is prevented from being lowered with time. In the embodiment, the heating temperature is not particularly limited, and can be appropriately set, for example, in the range of 80 to 140 ° C, preferably in the range of 85 to 120 ° C.
The heating time is not particularly limited, but can be appropriately set within a range of, for example, 20 seconds to 300 seconds, preferably 25 seconds to 180 seconds. When the heating time exceeds 300 seconds, the base material tends to shrink, and the appearance quality as an adhesive tape may deteriorate. The amount of heat history given to the polyolefin base material by the heating step is not particularly limited, and can be appropriately set in the range of, for example, 3 to 90 (kJ · s / g), preferably 4 to 54 (KJ · s / g). . Here, the amount of heat history applied to the polyolefin substrate by the heating step can be determined by the following method:
Heat history amount (kJ · s / g) = specific heat (kJ / g · ° C.) × rising temperature (° C.) × heating time (s).

  In the present invention, the elongation at break of the stretched polyolefin base material is 1 to 6%, preferably 2 to 4%. If the elongation at break is less than 1%, the tape may be cut and difficult to use when the tape is set on the tape cutter and pulled out. On the other hand, if it exceeds 6%, when the tape is cut with the blade of the cutter table, the tape tends to be stretched and the tape may be difficult to cut.

  In addition to the said base material, the adhesive tape of this invention is normally equipped with the adhesive layer. Adhesives that are the main component of the adhesive layer include solvent-based adhesives based on natural rubber, solvent-based adhesives based on a combination of natural rubber and synthetic rubber, natural rubber and tackifying resins, etc. Examples thereof include kneaded adhesives, latex rubber adhesives dispersed in water, acrylic solvent adhesives, and the like. The thickness of the pressure-sensitive adhesive layer is not particularly limited as long as it does not greatly affect the cut property with a tape cutter, but is preferably 5 to 60 μm, and more preferably 10 to 30 μm.

  In the present invention, the elongation at break can be measured by the method described in Examples of the present application.

  Examples of the pressure-sensitive adhesive tape of the present invention include a shape formed by winding a cylindrical core around a roll.

The manufacturing method of an adhesive tape This invention provides the manufacturing method of an adhesive tape including the process of irradiating an extended polyolefin base material with an electron beam.

  Examples of the stretched polyolefin base material used for electron beam irradiation include those described above for the pressure-sensitive adhesive tape of the present invention. In addition, the same kind of active energy and irradiation amount as described above can be used.

  The breaking elongation of the polyolefin substrate after irradiation is 1 to 6%, preferably 2 to 4%.

  The method for producing a pressure-sensitive adhesive tape of the present invention usually further comprises a step of laminating a pressure-sensitive adhesive layer on the stretched polyolefin substrate irradiated with the electron beam. The composition and thickness of the pressure-sensitive adhesive layer can be appropriately set as described above. The step of laminating the pressure-sensitive adhesive layer can be carried out according to a method known per se, such as a method of directly applying the pressure-sensitive adhesive composition to the substrate, a method of transferring and laminating the sheet-like pressure-sensitive adhesive layer to the substrate, and the like. Can be mentioned. In the step of applying the pressure-sensitive adhesive composition to the main body of the pressure-sensitive adhesive tape, the amount of the pressure-sensitive adhesive composition applied is not limited. For example, the amount of the pressure-sensitive adhesive after drying is appropriately within the range of the coating amount such that the thickness is about 5 to 60 μm. Can be set.

The present invention provides a method for improving the cutability of an adhesive tape with a tape cutter, comprising a step of irradiating a polyolefin substrate with an electron beam.

  Examples of the polyolefin base material used for electron beam irradiation and the electron beam irradiation amount include those described above for the pressure-sensitive adhesive tape of the present invention.

  The breaking elongation of the polyolefin substrate after irradiation with an electron beam is 1 to 6%, preferably 2 to 4%.

Example 1
(1) Preparation of pressure-sensitive adhesive composition The following raw materials were mixed to prepare a pressure-sensitive adhesive composition:
Natural rubber: 100 parts by weight Terpene phenol resin (Arakawa Chemical Co., Ltd.): 30 parts by weight Toluene (Sankyo Chemical Co., Ltd.): 600 parts by weight

(2) Manufacture of base material A tray conveyance irradiation experiment apparatus (manufactured by Eye Electron Beam Co., Ltd.) on Trefan (registered trademark) BO 2548 (biaxially oriented polypropylene film, double-sided corona discharge treatment) having a thickness of 40 μm, a width of 200 mm, and a length of 300 mm. CB250) was irradiated with a 50 kGy electron beam to obtain a substrate. The oxygen concentration in the atmosphere in the drying furnace in the drying step was about 20 ppm.

(3) Production of pressure-sensitive adhesive tape The pressure-sensitive adhesive composition prepared in (1) was applied on one surface of the base material obtained in (2) above using an applicator. After coating, after drying at 100 ° C. for 300 seconds in a drying oven, curing was carried out at 23 ° C. for 1 day to obtain an adhesive tape having a pressure-sensitive adhesive layer thickness of 15 μm.

(4) Measurement of elongation at break The pressure-sensitive adhesive tape obtained in (3) above was cut into a strip having a width of 18 mm, and the elongation at break was measured by the following method.

Measuring method of breaking elongation A sample 1 cut to 18 mm is fixed to a jig as shown in FIG. 1, and an upper chuck 2 and a cutter blade 3 used by a tape cutter PC-1 manufactured by Sekisui Chemical Co., Ltd. are attached to a portion of 100 mm in the pulling direction. Fix and pull at a pulling speed of 300 mm / min until the tape breaks.
The elongation at break is the elongation when the tape broke and was calculated by the following formula:
Elongation at break = (sample length at break-sample length before measurement) / (length between chuck and cutter blade) × 100.

Examples 2 to 11, Comparative Examples 1 and 2 and Reference Example Except for the base material and electron beam irradiation amount shown in Table 1, the production of the adhesive tape and the measurement of the elongation at break and the cutability were the same as in Example 1. Evaluation was performed. The cut property is evaluated as ○ when the elongation at break is 1 to 6%, and × when it is less than 1% or exceeds 6%. The measurement of elongation at break and the evaluation of cutability were performed immediately after the production of the adhesive tape and after storage at room temperature for 12 months. The elongation at break and the cutability of each example and comparative example are as shown in Table 1 below.

  As is apparent from Table 1, it can be seen that the adhesive tapes of Examples 1 to 11 are suppressed to the elongation at break equal to or lower than that of cellophane, despite using polypropylene as the base material. . Thus, it can be seen that the adhesive tapes of Examples 1 to 11 have the elongation at break within a certain range and are excellent in the cut ability by the tape cutter. On the other hand, the adhesive tapes of Comparative Examples 1 and 2 have a high elongation at break and are very inferior in cutability with a tape cutter.

Examples 12-15
The temperature of the drying step after coating the adhesive composition on one side of the substrate with an applicator on one side is 80 ° C as shown in Table 1 instead of 300 ° C for 300 seconds. A pressure-sensitive adhesive tape was obtained in the same manner as in Example 11 except that the temperature was set at ˜140 ° C. for 20 seconds to 300 seconds. The obtained adhesive tape was measured for elongation at break and evaluated for cutability. The measurement results are shown in Table 1 below.

Claims (3)

The manufacturing method of an adhesive tape including the process of irradiating an electron beam to a polyolefin base material, and the process of heating the polyolefin base material which irradiated the said electron beam at 80-140 degreeC for 20 second-300 second . Further comprising, method of producing a pressure-sensitive adhesive tape according to claim 1 the step of laminating an adhesive layer on a polyolefin substrate is irradiated with the electron beam. Improve the cutting property of the adhesive tape with a tape cutter, including the step of irradiating the polyolefin substrate with an electron beam and the step of heating the polyolefin substrate irradiated with the electron beam at 80 to 140 ° C. for 20 seconds to 300 seconds . Method.

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