JPH11152454A - 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 tear strengths of >=100 g from a low speed range to a high speed range at ordinary temperature (23 deg.C) and having a tear strength deterioration rate of <=50%. 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 portion of the fastening tape 10 is folded so that a release tape (or a release portion) 20 adhered to the inner surface on the back side of the disposable diaper 1.
It is stuck and stored. And at the time of wearing,
It is peeled off from the release tape 20 and used by being 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 addition, the user's usage is significantly different, and there is a problem that 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.

Accordingly, the inventors of the present application have made intensive efforts and focused on the tear strength of the base material for an adhesive tape, and the tensile speed at the time of measuring the tear strength has a specific tear strength in a low to high speed range. The present inventors have found that a base material that retains the material and has a lowering rate of tear strength in a range from a low tensile speed to a high tensile speed and satisfies a specific value meets the object of the present invention, and has completed the present invention.

[0008]

The pressure-sensitive adhesive tape substrate according to the present invention is a pressure-sensitive adhesive tape substrate comprising a polyolefin-based film, and has a tear strength at room temperature of 100 g from a low-speed region to a high-speed region. And the rate of decrease in tear strength is 50% or less.

In the present invention, the normal temperature refers to a value measured at 23 ° C., the low-speed region refers to a tensile speed of a tensile tester of 300 mm / min in a test method described later, and the high-speed region refers to a value measured later. 1 shows 100 m / min of a high-speed peeling test machine in the test method. Further, the tear strength refers to a measured value in a test method described later, and the rate of decrease in the tear strength is calculated from the minimum value and the maximum value of the tear strength in a low speed range to a high speed range obtained in the test by the following formula. Shall be referred to as the value. Reduction rate (%) = ｛1-
(Minimum / Maximum) 値 × 100

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 20-80% by weight in the blending composition of the blend film. If the blending amount is less than 10% by weight, sufficient tearing is required. Strength cannot be obtained, and the rate of decrease in tear strength increases.

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 weight%, the rate of decrease in tear strength increases, which is not preferred.

After these copolymers or metallocene linear low-density polyethylenes are dry-blended together with the polymer to be blended, they are formed 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 in 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 types of acrylic pressure-sensitive adhesives and rubber-based pressure-sensitive adhesives can be used. Can be.

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 manufacturing 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 LLDPE 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 Tear Strength] Using a tensile tester and a high-speed peeling tester, 300 mm / min.
Min, 50 m / min, 100 m / min at each pulling speed,
The tear strength was measured. When each adhesive tape base material was cut into a 50 mm square sample as a sample, and a cut of 25 mm was made in the forming (MD) direction, the left and right of the cut were gripped by chucks of a testing machine, and a test was performed. The maximum load (g) was determined as the tear strength. The measurement was performed in a thermostat at 23 ° C.
/ Min or more, a high-speed peeling tester was used.

[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.

[0034]

[Table 1]

[0035]

[Table 2]

As can be seen from Table 1, when a copolymer containing 3% or more of ethylene was used (Examples 1 and 2), a speed of 300 mm / min.
In a wide range of tensile speeds up to a high speed of 0 m / min, a good tear strength of 100 g or more was obtained,
The rate of decrease in tear strength was 50 for each of the adhesive tapes.
% Or less.

On the other hand, when the copolymer having an ethylene content of 3% or more is used at less than 10% (Comparative Examples 1 and 2), the tear strength may be less than 100 g, and the reduction rate of the tear strength may be 50%. %.

Further, metallocene LLDPE is added in an amount of 3 to 15%.
When it is contained (Examples 3 and 4), 300
In a wide range of tensile speeds from a low speed of mm / min to a high speed of 100 m / min, a good tear strength of 100 g or more was obtained, and the reduction rate of the tear strength was 50% or less in any of the adhesive tapes. there were.

On the other hand, when the metallocene LLDPE was not used (Comparative Example 3) and the conventional Ziegler LLDPE
(Comparative Example 4) in all cases, the tear strength may be less than 100 g, and the rate of decrease in tear strength may be 50.
%.

[Mounting 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.

[0041]

[Table 3]

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

[0043]

The tape substrate according to the present invention is a pressure-sensitive adhesive tape substrate comprising a polyolefin film,
The tear strength of the substrate at room temperature is 100 g or more in a low-speed range to a high-speed range, and the tear strength reduction rate is 50%.
% Or less. 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-based film, for example, a blend film containing 10% by weight or more of a copolymer having an ethylene content of 3% or more and a blend film containing 3 to 15% by weight of a metallocene linear low-density polyethylene are preferably used. Can be used.

[Brief description of the drawings]

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

[Description of Signs] 1 Disposable diaper 10 Fastening tape 11 Base 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 a tear strength at room temperature of 100 g or more from a low speed range to a high speed range, and a reduction rate of the tear strength is 50%.
% Or less. 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.