JPH11152455A - Substrate for self-adhesive tape and self-adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for self-adhesive tape for fixing a disposable diaper, especially suitable for a fastening tape. SOLUTION: This substrate for self-adhesive tape is obtained from a polyolefin film having a tear strength of >=100 g and an elongation of >=400% at a low temperature (0 deg.C). The polyolefin film is preferably, for example, a blend film containing a copolymer having an ethylene content of >=3% in an amount of >=10 wt.% or a blend film containing a metallocene linear low density polyethylene in an amount of 3-15 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate for an adhesive tape and an adhesive tape. Specifically, the present invention relates to a pressure-sensitive adhesive tape substrate having improved physical properties such as tear strength and a pressure-sensitive adhesive tape using the pressure-sensitive adhesive tape substrate, and more particularly to a pressure-sensitive adhesive tape suitably used for disposable diapers.

[0002]

2. Description of the Related Art Conventionally, polyolefin films such as polyethylene films and polypropylene films have been used.
It has been used as a substrate for various kinds of adhesive tapes. Especially,
For a tape for fixing disposable diapers, a blended film of polypropylene and polyethylene has been often used as a base material for the tape because of its availability at low cost.

[0003] However, these conventional adhesive tapes using a blend film as a base material cannot obtain excellent properties such as tear strength.

[0004] For example, as a fixing tape for disposable diapers, for example, as shown in FIG. 1, a fastening tape 10 having an adhesive layer 12 formed on one surface of a tape base material 11.
However, a part thereof is attached to the outer surface on the back side of the disposable diaper 1. The remaining part of the fastening tape 10 is
Release tape (or release part) attached to the inner surface on the back side of disposable diaper 1 so as to be folded
20 and stored. When the disposable diaper is attached, it is peeled off from the release tape 20 and attached to a frontal portion (not shown) on the front surface of the disposable diaper. Therefore, the fastening tape 10 is repeatedly peeled off from the release tape 20 or the frontal portion.

[0005] At this time, when the conventional blend film is used as a fastening tape, the fastening tape is torn when peeled from the release tape or the frontal portion, which has been a major cause of complaints in the market. In particular, there has been a problem that the usage of the user is remarkably different, and it is not possible to cope with all kinds of peeling speeds, such as peeling slowly or quickly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and has as its object to provide a base material for an adhesive tape suitable for a fixing tape for disposable diapers, particularly a fastening tape.

The inventors of the present invention have made intensive efforts to pay attention to the elongation and tear strength of the adhesive tape substrate in the low-temperature region, and have investigated the elongation and tear strength of the adhesive tape substrate at 0 ° C. Found that a base material satisfying the specified value met the object of the present invention, and completed the present invention.

[0008]

The pressure-sensitive adhesive tape base material according to the present invention is a pressure-sensitive adhesive tape base material made of a polyolefin-based film, and has a substrate elongation at a low temperature of 400%.
% Or more, and the tear strength is 100 g or more.

In the present invention, low temperature means a value measured at 0 ° C., and elongation and tear strength refer to values measured by a test method described later.

The polyolefin film used for the base material for the pressure-sensitive adhesive tape of the present invention is not particularly limited, but it is particularly preferable to use a blend film containing a copolymer as described below.

As the copolymer, a copolymer having an ethylene content of 3% or more, preferably 5 to 10%, for example, propylene / ethylene copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / acrylic acid copolymer, ethylene /
Examples thereof include a methacrylic acid copolymer and an ethylene / vinyl alcohol copolymer, and one or more of these may be used. In addition, ethylene content shall show the ethylene compounding rate in a compounding composition.

The polymer blendable with these copolymers is not particularly limited.
For example, polypropylene, polystyrene, high density polyethylene (HDPE) and low density polyethylene (LDPE)
And the like can be used, and it is selected in consideration of the viewpoint of blendability with the above copolymer and the characteristics of the obtained film.

At this time, the blending amount of the copolymer must be 10% by weight or more, preferably 20 to 80% by weight in the blending composition of the blend film. If the blending amount is less than 10% by weight, sufficient elongation is required. Rate cannot be obtained,
Further, sufficient tear strength cannot be obtained.

Alternatively, a metallocene linear low-density polyethylene (Metallocene L) may be used as the polyolefin film.
A blend film containing (LDPE) can be used. The metallocene linear low-density polyethylene, unlike the conventional linear low-density polyethylene obtained using a so-called Ziegler catalyst, refers to a linear low-density polyethylene obtained using a so-called metallocene catalyst, ethylene polymer and It contains both a copolymer of ethylene and an α-olefin. The α-olefin used at this time is not particularly limited, and various comonomers such as 1-butene, 1-hexene and 1-octene can be exemplified, and one or more of these can be used. .

The polymer blended with the metallocene linear low-density polyethylene is not particularly limited. For example, various polymers such as polypropylene, polystyrene, high-density polyethylene and low-density polyethylene may be used as described above. It can be selected in consideration of the blendability with the above copolymer and the characteristics of the obtained film.

At this time, the metallocene linear low-density polyethylene needs to be contained in an amount of 3 to 15% by weight in the blend composition of the blend film. If the amount is less than 3% by weight, sufficient tear strength cannot be obtained, and
If it is added in excess of wt%, the elongation does not increase, which is not preferred.

These copolymers or metallocene LLDs
PE is dry-blended together with the polymer to be blended, and then made into a film according to a conventional method such as a T-die method or an inflation method.

Further, if necessary, various additives such as a filler, a pigment, an antistatic agent, a lubricant, an ultraviolet absorber and an antioxidant may be added to the polymer to form a film. At this time, the thickness of the base material for an adhesive tape according to the present invention is not particularly limited, but is usually 50 to 300 μm.

The pressure-sensitive adhesive tape according to the present invention is characterized in that a pressure-sensitive adhesive layer is formed on at least one surface of the pressure-sensitive adhesive tape substrate according to the present invention.

The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer is not particularly limited as long as it is generally used as a general pressure-sensitive adhesive tape, and various acrylic pressure-sensitive adhesives and rubber-based pressure-sensitive adhesives are used. be able to.

The pressure-sensitive adhesive tape thus obtained can be used for various applications such as a pressure-sensitive adhesive tape for packing or a tape for fixing a disposable diaper. Particularly in applications that can be repeatedly peeled, such as fastening tapes for disposable diapers, a reliable fastening tape can be provided, and it is not easily torn at any speed.

[0022]

EXAMPLES Next, according to the following compounding ratios and preparation methods, base materials for pressure-sensitive adhesive tapes of various examples according to the present invention and base materials for pressure-sensitive adhesive tapes of comparative examples were prepared. The effect was confirmed.

(Example 1) MFR4.5 homopolypropylene 60% MFR6.0 random polypropylene 25% (ethylene content: about 8%) MFR4.0 low-density polyethylene 15%

(Example 2) MFR4.5 homopolypropylene 40% MFR6.0 random polypropylene 45% (ethylene content about 8%) MFR4.0 low-density polyethylene 15%

Example 3 Homopolypropylene of MFR1.0 90% Metallocene LLDEP of MFR1.0 5% Low-density polyethylene of MFR4.0 5%

Example 4 MFR1.0 Homopolypropylene 85% MFR1.0 Metallocene LLDPE 10% MFR4.0 Low Density Polyethylene 5%

Comparative Example 1 85% homopolypropylene with MFR 4.5 15% low density polyethylene with MFR 4.0

(Comparative Example 2) 80% homopolypropylene with MFR 4.5 5% random polypropylene with MFR 6.0 (8% ethylene content) 15% low density polyethylene with MFR 4.0

(Comparative Example 3) 85% homopolypropylene with MFR 1.0 15% low density polyethylene with MFR 4.0

Comparative Example 4 MFR 1.0 homopolypropylene 85% MFR 2.0 Ziegler LLDPE 10% MFR 4.0 low density polyethylene 5%

[Manufacturing method] After the respective materials were dry-blended at the above mixing ratios, the mixture was supplied to the hopper of a single-screw extruder and T-die-molded at about 240 ° C. The adhesive tape base materials of Examples 1 to 4 were obtained. Thereafter, a backside treatment and a hot-melt adhesive were applied to form an adhesive tape. In addition, the thickness of the base material for an adhesive tape was 100 μm.

[Measurement of Elongation] The elongation (CD direction) was measured using a tensile tester at a tensile speed of 300 mm / min. The measurement was carried out in a thermostat at 0 ° C., and the elongation (%) was calculated with the length before the measurement taken as 100. The measurement sample was 10 mm in width, and the interval between the knobs of the tensile tester was 25 mm.

[Measurement of tear strength] Using a tensile tester,
The tear strength was measured at a tensile speed of 300 mm / min. As a measurement sample, each pressure-sensitive adhesive tape base material was cut into a square of 50 mm, and a cut of 25 mm was made in the forming (MD) direction. The maximum load (g) was taken as the tear strength. In addition, the measurement was performed in a 0 degreeC thermostat.

[Test Results] Table 1 shows the test results when a copolymer having an ethylene content of 3% or more was used, and Table 2 shows the test results when a metallocene linear low-density polyethylene was used.
Respectively.

[0035]

[Table 1]

[0036]

[Table 2]

As can be seen from Table 1, when a copolymer containing 3% or more of ethylene was used (Examples 1 and 2), the elongation was 500% or more, and the tear strength was 150 g or more. I got

On the other hand, when a copolymer having an ethylene content of 3% or more is used at less than 10% (Comparative Examples 1 and 2), the elongation is about 200% and the tear strength is 100 g.
It was less than.

The metallocene LLDPE is added in an amount of 3 to 15%.
In the case of containing (Examples 3 and 4), the elongation was 500% or more, and the tear strength was also a good value of 150 g or more.

On the other hand, the case where no metallocene LLDPE was used (Comparative Example 3) and the case where the conventional Ziegler LLDPE
Was used (Comparative Example 4), the elongation was less than 400%, and the tear strength was sometimes less than about 100 g.

[Installation Test] Next, the adhesive tapes of Examples 1 to 4 and Comparative Examples 1 to 4 were used as fastening tapes for disposable diapers, and actually used for disposable diapers as shown in FIG. The test was performed. Fifteen monitors were asked to use two diapers for each person according to their own use and tested for tearing.
Table 3 shows the results.

[0042]

[Table 3]

As can be seen from Table 3, when the pressure-sensitive adhesive tape of each example was used, it was possible to peel off the release tape repeatedly without tearing, but when the pressure-sensitive adhesive tape of the comparative example was used, Some cases were torn.

[0044]

The tape substrate according to the present invention is a pressure-sensitive adhesive tape substrate comprising a polyolefin film,
The elongation percentage of the substrate at a low temperature is 400% or more, and the tear strength is 100 g or more. Therefore, using the base material, for example, when making a fastening tape for disposable diapers, by any method of pulling, without tearing the tape base material, can be peeled off from a release tape and the like, A reliable fastening tape can be provided.

As the polyolefin film, for example, a blend film containing 10% by weight or more of a copolymer having an ethylene content of 3% or more, a blend film containing 3 to 15% by weight of a metallocene linear low-density polyethylene, and the like are preferably used. Obtainable.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one form of a fixing tape for a disposable diaper.

[Explanation of symbols]

 Reference Signs List 1 disposable diaper 10 fastening tape 11 base material for adhesive tape 12 adhesive layer 20 release tape

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08L 23/08 A41B 13/02 JB29K 23:00 (72) Inventor Yoshio Nakagawa 1-1-1 Shimohozumi, Ibaraki-shi, Osaka No. 2 Nitto Denko Corporation

Claims (5)

[Claims] 1. A pressure-sensitive adhesive tape substrate comprising a polyolefin-based film, wherein the substrate has an elongation at a low temperature of 400% or more and a tear strength of 100 g or more. Wood. 2. The pressure-sensitive adhesive tape substrate according to claim 1, wherein the polyolefin-based film is a blend film containing a copolymer having an ethylene content of 3% or more by 10% by weight or more. 3. The polyolefin-based film comprises a blend film containing 3 to 15% by weight of a metallocene linear low-density polyethylene.
The base material for an adhesive tape according to the above. 4. A pressure-sensitive adhesive tape, wherein a pressure-sensitive adhesive layer is formed on at least one surface of the pressure-sensitive adhesive tape base material according to claim 1, 2, or 3. 5. The pressure-sensitive adhesive tape according to claim 4, which is used by being attached to a disposable diaper.