JPH1121528A - Pressure-sensitive adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: (J) To improve mechanical strength and hand-cutting properties by providing a specific low-melting polyolefinic laminate layer on one or both sides of a polyolefinic resin-made fabric. SOLUTION: On one or both sides of a polyolefinic resin-made fabric formed of threads having a draw ratio of 2-8 and a single yarn size of 50-200 denier as longitude and threads having a draw ratio of 5-15 and a single yarn size of 150-600 denier as latitude, is laminated a low-melting polyolefin selected from copolymers comprising 50-95 wt.% of ethylene and 50-5 wt.% of α-olefin, which is produced by using a metallocene catalyst and has a melt flow index of 1-30 g/10 min., a density of 0.87-0.96 g/cm<3> , a maximum peak temperature by DSC of 70-125 deg.C and a molecular weight distribution (Mw/Mn) of 1.8-3.0 or syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more and a melt flow index of 1-30 g/10 min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive tape, and more particularly, to a polyolefin-based resin fabric provided with a laminate layer comprising a component containing a specific low-melting-point polyolefin, and having excellent mechanical strength and hand-cutting properties. Related to a good adhesive tape.

[0002]

2. Description of the Related Art A pressure-sensitive adhesive tape is formed by applying a pressure-sensitive adhesive to one surface of a base material made of a cloth, and can be easily cut to a required length by hand and lightly pressed with a fingertip. It is a convenient tape that can be adhered just by doing, but it is usually used for packaging or connecting materials that apply force as packing material and curing material, so it keeps sufficient mechanical strength in the longitudinal direction There is a demand for good hand-cutting properties that can be easily cut by hand without using a cutter or the like in the weft direction.

[0003] As the constitution of this adhesive tape, a tape in which a laminate layer is provided on the surface of a cloth and a pressure-sensitive adhesive is applied to the surface of the laminate layer is often used. This is because when the laminating layer makes the surface smooth and the pressure-sensitive adhesive can be applied uniformly in a thin layer, the filament of the fabric constituting the fabric is firmly fixed, and when a tearing force is applied in the weft direction The purpose of the present invention is to prevent warp yarns from escaping, and to act so as not to cause unevenness in hand cutting properties.

[0004] In such an adhesive tape, the mechanical strength in the warp direction becomes weaker in order to improve the hand-cutting property in the weft direction, and the hand-cutting property in the weft direction deteriorates when the mechanical strength in the warp direction is increased. In addition, it has not been easy to simultaneously improve the mechanical strength in the warp direction and the hand-cutting property in the weft direction.
In order to solve such problems, various attempts have been made to provide a difference in strength between the warp and the weft, for example, a method of setting the fineness of the weft to two to three times the fineness of the warp, and the draw ratio of the weft to the warp. And a method for increasing the driving density of the weft to be higher than the driving density of the warp.

[0005] However, even in a cloth formed by providing a difference in strength between the weft and the warp, if the melting point of the resin constituting the laminate layer is not so low, both the warp and the weft are melted by the ordinary extrusion lamination method. Due to the thermal degradation at the extrusion temperature, the mechanical strength is uniformly reduced, and there is a problem that it is difficult to maintain the difference in the strength initially provided between the weft and the warp. Attempts have also been made to increase the difference in strength between the weft and the warp by using the thermal degradation at the melt extrusion temperature of the extrusion laminating method to greatly degrade the warp having a small fineness, thereby reducing the mechanical strength due to thermal degradation. Since it is uncertain, it is difficult to finish the product as designed with a predetermined difference in strength between the weft and the warp, such as reducing the tear strength in the weft direction without significantly reducing the tensile strength in the warp direction. there were.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention reduces the influence of mechanical strength due to uncertain thermal deterioration of a fabric in a process of providing a laminate layer, and designs warp and weft yarns. It is an object of the present invention to provide a pressure-sensitive adhesive tape having excellent mechanical strength and good hand-cutting property by providing a predetermined strength difference as described above.

[0007]

Means for Solving the Problems The present inventors have found means capable of solving the above-mentioned problems by providing a laminate layer made of a resin having a specific property to a fabric.
The present invention has been completed.

[0008] That is, the pressure-sensitive adhesive tape of the present invention is formed by forming a tape base by providing a laminate layer on at least one side of a polyolefin resin fabric, and providing a pressure-sensitive adhesive layer on at least one side of the tape base. An adhesive tape, wherein the laminate layer is selected from an ethylene / α-olefin copolymer produced using a metallocene catalyst or a syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more. It is characterized by being composed of a component containing a polyolefin having a melting point.

The resin constituting the laminate layer of the pressure-sensitive adhesive tape of the present invention has a lower melting point than, for example, polyethylene or polypropylene produced using a conventional Ziegler catalyst or the like, so that it can be extruded at a lower temperature. it can.
Therefore, polyethylene or polypropylene according to a conventional method is used as the fabric, and ethylene / α is used as the laminate layer.
-When a component containing an olefin copolymer or a syndiotactic polypropylene is used, the difference in melting point between the resin of the fabric and the resin of the laminate layer is increased, so that thermal degradation due to the melt extrusion temperature that the fabric undergoes in the step of providing the laminate layer. The effect of tensile strength in the longitudinal direction
It is possible to obtain an adhesive tape excellent in hand cutting property in the weft direction.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polyolefin resin fabric of the present invention is a woven fabric woven using flat yarns formed of a polyolefin resin as warp yarns, or the flat yarns are substantially stretched in the warp direction and the weft direction. It is a nonwoven fabric which is arranged in parallel, overlapped, and heat-welded at intersections.

The above-mentioned polyolefin resins include polyethylene resins such as high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer. And polypropylene-based resins such as polypropylene and propylene-ethylene copolymer. Among these, high-density polyethylene, polypropylene, and the like produced by a known Ziegler-based catalyst or the like are preferable because high strength can be obtained by a stretching treatment.

The above-mentioned flat yarn is formed into a film by a T-die flat method or an inflation method using a polyolefin resin, and after cooling, slit into a narrow width.
It is obtained by heating and stretching. As the flat yarn formed here, the draw ratio is preferably 2 to 8 times as the warp, and the single yarn fineness is 50 to 200 denier (hereinafter referred to as d).
The draw ratio is preferably 5 to 5 as a weft.
Fifteen times, the single yarn fineness is 150 to 600 d.

The flat yarn may be a composite yarn comprising two or more kinds of polyolefin resins having different melting points, of which a high melting point component is an intermediate layer and a low melting point component is both outer layers. In particular, it is more preferable that the cloth is a laminated nonwoven fabric because thermal degradation at the time of heat welding at intersections can be suppressed. As the high melting point component, high density polyethylene,
Medium-density polyethylene, linear low-density polyethylene, polypropylene and the like are preferable, and as the low-melting point component, low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, propylene-ethylene copolymer, etc. Are preferably used, and furthermore, an ethylene / α-olefin copolymer or a syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more produced using the metallocene catalyst which is the low-melting polyolefin of the present invention. Is also preferably used. As a method for forming the above-described composite yarn, a known technique may be adopted. A laminated flat yarn is formed by slitting at least three layers of a film coextruded by a multi-layer T-die flat method or an inflation method, and then stretching. And heat-treated.

The fabric using the flat yarn as a warp yarn preferably has a driving density of 3%.
The range is from 0 to 60 yarns / inch, and from 10 to 30 inches as weft, and the ratio of warp / weft is 1/3 to 1/2.
Is preferable.

The fabric preferably has a tensile strength in the warp direction of 30 kgf / 5 cm or more in terms of usability, and a tear strength in the weft direction of 1 kgf or less, more preferably 0.5 kgf, in terms of hand cutting. .

The thus obtained fabric is provided with a laminate layer of a low-melting-point polyolefin on at least one surface to form a tape base material. This low-melting-point polyolefin is a component containing an ethylene / α-olefin copolymer produced using a metallocene catalyst when the polyolefin resin used for the flat yarn of the fabric is a polyethylene resin, In the case of a polypropylene resin, the syndiotactic pentad fraction is 0.7.
The component containing the syndiotactic polypropylene described above is preferable for improving the adhesiveness.

The low-melting-point polyolefin used in the laminate layer of the present invention includes an ethylene / α-olefin copolymer produced using a metallocene catalyst or a syndiotactic pentad having a syndiotactic pentad fraction of 0.7 or more. It is composed of components containing tic polypropylene.

The ethylene / α-olefin copolymer produced using the above metallocene catalyst has the following (a) to
An ethylene / α-olefin copolymer comprising ethylene having the physical properties (d) and an α-olefin having 3 or more carbon atoms. That is, (a) melt flow rate (MFR)
Is 0.1 to 30 g / 10 min., Preferably 1 to 10 g.
/ 10 min. (B) density of 0.87~0.96g / cm ^3, preferably 0.90~0.93g / cm ^3. (C) Maximum peak temperature (Tm) by DSC is 70 to 1
The temperature is 25 ° C, preferably 80 to 100 ° C. (D) The molecular weight distribution (Mw / Mn) is 1.8 to 3.0, preferably 2.2 to 3.0. In the ethylene / α-olefin copolymer out of the range of (a) to (d), the difference in melting point from the polyethylene resin produced by using a conventional Ziegler catalyst or the like is small, and the object of the present invention is reduced. Cannot be achieved.

The method for producing the ethylene / α-olefin copolymer is described in JP-A-58-19309 and JP-A-5-19309.
JP-A-9-95292, JP-A-60-35005, JP-A-60-35006, JP-A-60-35
No. 007, JP-A-60-35008, JP-A-60-35009 and the like, and can be obtained by using a metallocene catalyst. The metallocene catalyst is, for example, a catalyst composed of a metallocene compound represented by bis (cyclopentadienyl) zirconium dichloride (Cp ₂ ZrCl ₂ ), methylaluminoxane (MAO) and the like.

As the α-olefin to be copolymerized with ethylene, α-olefins having 3 or more carbon atoms, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-hexene
Octene, 4-methyl-1-pentene and the like.
Of these, one or two or more α-olefins may be copolymerized with 5 to 50% by weight, preferably 10 to 30% by weight, of ethylene with 50 to 95% by weight, preferably 70 to 90% by weight. .

The ethylene / α-olefin copolymer produced by using the metallocene catalyst used as the low-melting polyolefin is usually used alone, but may be an ultra-low-density polyethylene, a low-density polyethylene, or a linear low-density polyethylene. Polyethylene resins such as polyethylene, ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer may be used in combination, and these may be used alone or in combination of two or more. Here, the mixing ratio of the polyethylene resin used in combination may be in the range of 0 to 95% by weight, and the moldability can be improved by mixing the polyethylene resin in this manner.

On the other hand, syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more is
^A syndiotactic polypropylene having a syndiotactic pentad fraction of 0.7 or more measured by ¹³ C-NMR, preferably a syndiotactic polypropylene having a syndiotactic pentad fraction of 0.8 or more. If the syndiotactic pentad fraction is less than 0.7, the difference in melting point from a polypropylene resin produced using a conventional Ziegler-Natta catalyst or the like is small, and the object of the present invention cannot be achieved.

Methods for producing syndiotactic polypropylene are described in JP-A-2-41303, JP-A-2-41305, JP-A-2-274703, JP-A-2-274704, and JP-A-3-274. 179
No. 005, JP-A-1-79006 and the like, and can be obtained by polymerizing propylene using a metallocene catalyst. This metallocene catalyst is, for example, a metallocene compound having an asymmetric ligand represented by isopropyl (fluorenyl) (cyclopentadienyl) zirconium dichloride, and a catalyst composed of methylaluminoxane (MAO) and the like as cocatalysts. is there.

The above syndiotactic polypropylene may be a propylene homopolymer or a copolymer with an α-olefin other than propylene, for example, ethylene, butene-1, 4-methylpentene-1 or the like. The syndiotactic polypropylene has an MFR of preferably 1 to 30 g / 10 min., More preferably 5 to 30 g / 10 min.
It is selected in the range of 20 g / 10 min.

The syndiotactic propylene having a syndiotactic pentad fraction of 0.7 or more used as the low-melting-point polyolefin is usually used singly. You may use together with an ethylene copolymer. The propylene-ethylene copolymer is a propylene-ethylene copolymer produced by a known method, and either a block or random copolymer is used. Among these propylene-ethylene copolymers, a random copolymer having a low melting point is preferred. Here, the blending ratio of the propylene-ethylene copolymer used in combination may be in the range of 0 to 95% by weight, and the moldability can be improved by mixing the propylene-ethylene copolymer in this manner. .

In the present invention, a tape base is obtained by providing a laminate layer on at least one surface of the woven or nonwoven fabric. As this lamination method,
Known techniques such as an extrusion laminating method, a dry laminating method, and a thermocompression laminating method can be employed, but an extruding laminating method which has excellent adhesion between a laminate layer and a fabric and is capable of high-speed processing is preferable. Here, the thickness of the laminate layer is usually set to 15 to 60 μm.

A pressure-sensitive adhesive layer is provided on at least one surface of the tape base material thus obtained to form an adhesive tape. Examples of the pressure-sensitive adhesive include acrylic, silicone, vinyl, and natural rubber. A known material such as a synthetic rubber can be used, and a predetermined amount may be applied depending on the application.

[0028]

【Example】

(Test method) 1. MFR: JIS-K6760, JIS-K6758
2. Density: JIS-K6760, JIS-K6758 3. Melting point (DSC method): JIS-K7121 compliant 4. Mw / Mn: GPC method 5. Syndiotactic pentad fraction: [Macro
moleculars, Vol. 13, 267 (198
0)] In accordance with the method described in 6. Tensile test: JIS-L1096 compliant 7. Tear test: JIS-P8116 compliant

Example 1: High density polyethylene (MFR =
(1.2 g / 10 min., Tm = 130 ° C.), a film is formed by an inflation method, cooled, stretched after slit at a stretching temperature of 120 ° C., and an annealing temperature of 125 ° C.
Then, a flat yarn having a fineness of 100 d was obtained by 6-fold drawing by a hot plate contact drawing method to obtain a warp. Similarly, a flat yarn having a fineness of 300 d was obtained by drawing four times to obtain a weft.
These warps and wefts were woven by a Sulzer loom at a driving density of 46 / inch for the warp and 18 / inch for the weft to obtain a flat yarn woven fabric.

On both sides of this flat yarn woven fabric, an ethylene / α-olefin copolymer (MFR = 12) produced using a metallocene catalyst as a low-melting polyolefin.
g / 10 min., density = 0.911 g / cm ³ , Tm =
96 ° C., Mw / Mn = 2.1) melt extrusion temperature 270 ° C.
By using an extrusion laminating method, a laminate having a thickness of 30 μm was provided to form a tape base material. After performing a corona discharge treatment on one surface of the tape base material, a butyl rubber-based pressure-sensitive adhesive was applied to obtain an adhesive tape. Table 1 shows the results of evaluating the physical properties of this adhesive tape.

Comparative Example 1: Flat yarn used in Example 1
On both sides of the woven fabric, a normal low density polyethylene (MFR =
15 g / 10 min., Density = 0.918 g / cm ³ , T
m = 104 ° C.), and a laminate having a thickness of 30 μm was provided by an extrusion lamination method at a melt extrusion temperature of 290 ° C. to form a tape base material. This tape base material was used in the same manner as in Example 1 and the evaluation results are shown in Table 1.

Example 2 An ethylene / α-olefin copolymer (MFR = 12 g / 10 min., Produced using a metallocene catalyst as a low-melting polyolefin) on both surfaces of the flat yarn woven fabric used in Example 1. Density = 0.9
11 g / cm ³ , Tm = 96 ° C., Mw / Mn = 2.1) and low-density polyethylene (MFR = 15 g / 1).
0 min., Density = 0.918 g / cm ³ , Tm = 104
C.) and a weight of 30 μm by extrusion lamination at a melt extrusion temperature of 280 ° C.
m was provided to form a tape base material. This tape base material was used in the same manner as in Example 1 and the evaluation results are shown in Table 1.

Example 3: Polypropylene (MFR = 1.
7 g / 10 min., Tm = 156 ° C.), a film is formed by an inflation method, cooled, slit, stretched at 150 ° C., annealed at 155 ° C., stretched 8 times by hot plate contact stretching, and fineness is adjusted. A 100d flat yarn was obtained and used as a warp. Next, a flat yarn having a fineness of 300 d was obtained by a 6-fold drawing in the same manner to obtain a weft. These warps and wefts were woven by a Sulzer loom at a driving density of 46 / inch for the warp and 18 / inch for the weft to obtain a flat yarn woven fabric.

On both sides of the flat yarn woven fabric, a syndiotactic polypropylene (syndiotactic pentad fraction = 0.82, MFR = 18.0 g /
10 min., Mw / Mn = 2.0, Tm = 130 ° C.) at a melt extrusion temperature of 280 ° C. by an extrusion laminating method, each having a thickness of 3 mm.
A tape base was formed by providing a 0 μm laminate layer.
This tape base material was used in the same manner as in Example 1 and the evaluation results are shown in Table 1.

Comparative Example 2: On both sides of the flat yarn woven fabric used in Example 3, a normal propylene-ethylene random copolymer (MFR = 20.0 g / 10 min., Ethylene content = 6.0 mol%, Tm = 148 ° C.)
And a melt extrusion temperature of 300 ° C.
By using an extrusion laminating method, a laminate having a thickness of 30 μm was provided to form a tape base material. This tape base material was used in the same manner as in Example 1 and the evaluation results are shown in Table 1.

Example 4: On both surfaces of the flat yarn woven fabric used in Example 3, a syndiotactic polypropylene (syndiotactic pentad fraction = 0.8) was produced as a low-melting polyolefin using a metallocene catalyst.
2, MFR = 18.0 g / 10 min., Mw / Mn =
2.0, Tm = 130 ° C.)
Ethylene random copolymer (MFR = 20.0 g / 10
min., ethylene content = 6.0 mol%, Tm = 148
C.) and a weight of 30 μm by extrusion lamination at a melt extrusion temperature of 290 ° C.
m was provided to form a tape base material. This tape base material was used in the same manner as in Example 1 and the evaluation results are shown in Table 1.

In Table 1, Me-PE is an ethylene / α-olefin copolymer produced using a metallocene catalyst, and Me-PP is a syndiotactic polymer produced using a metallocene catalyst. Tic polypropylene and LDPE are ordinary low density polyethylene, PP
-PE indicates a normal propylene-ethylene random copolymer.

[0038]

[Table 1]

[0039]

As described above, the pressure-sensitive adhesive tape of the present invention can be produced by using a metallocene catalyst having a lower melting point than polyethylene and polypropylene produced by a conventional Ziegler catalyst or the like. Since a low-melting-point polyolefin selected from components containing an olefin copolymer or a syndiotactic propylene having a syndiotactic pentad fraction of 0.7 or more is used as a laminate layer, the warp and the warp in the extrusion lamination method are used. The effect of reducing the mechanical strength of the weft due to thermal deterioration is reduced, and the tear strength in the warp direction is reduced while the tensile strength in the warp direction is maintained with the designed strength difference given to the warp and the weft. An adhesive tape having excellent strength and good hand-cutting properties can be obtained.

Claims (1)

[Claims] 1. A pressure-sensitive adhesive tape comprising a tape base material formed by providing a laminate layer on at least one surface of a polyolefin resin fabric, and a pressure-sensitive adhesive layer provided on at least one surface of the tape base material. The laminating layer has an ethylene / α-olefin copolymer or syndiotactic pentad fraction produced using a metallocene catalyst of 0.7.
A pressure-sensitive adhesive tape comprising a component containing a low-melting-point polyolefin selected from the above-mentioned syndiotactic polypropylene.