JP2002036406A - Laminate film showing excellent hand cutting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film suitable for a base material of an adhesive tape showing an improved hand cutting without decreasing tensile strength. SOLUTION: A laminate film comprises (a) a thermoplastic resin film comprising a thermoplastic resin support and a plurality of protrusions arranged in a predetermined pattern formed into one body on one surface of the support and (b) a thermoplastic resin layer laminated on the surface of the arranged protrusions in such a manner that the resin fills a clearance between the protrusions, wherein an air layer is mounted between the surface of the support between the protrusions of the thermoplastic resin film (a) and the thermoplastic resin layer (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent so-called hand-cutting properties, which can be easily cut by human hands.
The present invention relates to a laminated film excellent in flexibility and suitable for a base material of an adhesive tape.

[0002]

2. Description of the Related Art Adhesive tapes based on cloth can be cut linearly by human hands relatively easily, that is, they have excellent hand-cutting properties. In the case of an adhesive tape using a film as a base material, the cutting line was not aligned with the width of the tape, and a manual cutting operation was required.

[0003] Therefore, it has been proposed that such a thermoplastic resin film is subjected to various treatments so as to impart hand-cutting properties. For example, Japanese Patent Publication No. 50-13306 discloses an adhesive tape in which one surface of an extruded thermoplastic resin film is embossed to form an uneven portion and the other surface is provided with an adhesive layer. I have. It is thought that the hand-cutting property has been improved by providing the irregularities on the surface of the thermoplastic resin film.However, when such an adhesive tape is wound in a roll, the irregularities come into contact with the adhesive layer, and the adhesive is formed. This unevenness is transferred to the surface of the agent layer, the surface of the pressure-sensitive adhesive is not smooth, the adhesion to an adherend is reduced, and as a result, there is a problem that the adhesive performance is reduced.

In Japanese Patent Application Laid-Open No. Hei 3-47885,
An adhesive tape is disclosed in which one surface of a polyolefin resin film is made a smooth surface, and the other surface is provided with an uneven portion by embossing, and an adhesive layer is provided on the uneven surface. According to this tape, it is possible to prevent the above-described deterioration of the adhesive performance, and it is possible to provide hand-cutting properties. However, in this pressure-sensitive adhesive tape, the pressure-sensitive adhesive is applied to the uneven surface to form the pressure-sensitive adhesive layer. However, there is a problem that is sometimes poor.

In order to solve these problems, Japanese Patent Application Laid-Open No.
In JP-A-324155, a polyethylene layer is laminated on an embossed surface in a thermoplastic resin film in which one surface is a smooth surface and the other surface is an embossed surface, and an adhesive layer is formed on the smooth surface. Is disclosed. Since both surfaces of the base material of the pressure-sensitive adhesive tape are smooth, the above-described problem can be solved. However, embossing applied to a thermoplastic resin film is performed by forming a concave portion in a smooth film with an embossing roll, and the strength of the concave portion is reduced, so that the hand cutting property is improved, but the tensile strength is improved. Is reduced.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a film suitable for a base material of an adhesive tape, which has improved hand-cutting properties without lowering tensile strength. The purpose is to do.

[0007]

In order to solve the above problems, according to the present invention, (a) a support of a thermoplastic resin,
On one surface of the support, a thermoplastic resin film composed of a plurality of protrusions arranged in a predetermined pattern integrally with the support, and (b) the protrusions of the thermoplastic resin film are arranged. On the surface that has been formed, a laminated film composed of a thermoplastic resin layer laminated so as to fill the gap between the protrusions and the protrusions, the thermoplastic resin film (a)
Surface and thermoplastic resin layer between protrusions
An air space is provided between (b).

In the laminated film of the present invention, the projections are arranged in a predetermined pattern integrally with the support, and an air layer exists between the projections. However, when they are cut by hand, the stress is concentrated on the base between the protrusions, and is arranged along the protrusions, that is, the arrangement of the protrusions, when the resin is cut by hand because the resin layers are interposed therebetween. Can be easily cut straight. And this hand-cutting property, the proportion occupied by the protrusions, the arrangement thereof, the thickness of the support provided with the protrusions, the thickness of the resin layer laminated on the protrusions, the type of these resins, and It can be set arbitrarily by changing the amount of the air layer. Furthermore, any physical property can be imparted to the laminated film depending on the combination of the resins used.

[0009]

FIG. 1 shows an embodiment of the laminated film of the present invention. As shown, the laminated film 1 includes a thermoplastic resin support 4 and a plurality of protrusions 5 arranged on one surface of the support and integrally with the support. It is composed of a resin film 2 and a thermoplastic resin layer 3 that is laminated on the surface of the thermoplastic resin film 2 where the projections are arranged so as to fill the gap between the projections. . An air layer 6 is provided between the surface of the support 4 between the protrusions of the film 2 and the thermoplastic resin layer 3.

As the support 4 of the thermoplastic resin film 2, polyolefin resins such as low-density polyethylene, high-density polyethylene, and polypropylene, mixtures of polyolefin resins, polyester resins, and the like can be used. The thickness of the support 4 is preferably 0.01 to 0.5 mm. If the thickness is less than 0.01 mm, the strength of the obtained film will be low, and if it is more than 0.5 mm, favorable hand-cutting properties cannot be obtained.

The projections 5 provided on one surface of the support 2 can also be made of a polyolefin resin such as low-density polyethylene, high-density polyethylene, or polypropylene, a mixture of polyolefin resins, or a polyester resin. The support may be the same or different. The shape of the projection is not particularly limited, and the shape of the cross section may be any of a circle, an ellipse, and a polygon. The height of the projections is substantially uniform, and the height of the projections is 0.05 to 5 in view of the hand-cutting property and strength of the obtained film.
mm, and the thickness of the projection is preferably a thickness that does not make contact with an adjacent projection. The distance between the protrusions is 0.05 to
It is preferably 2.5 mm. The number of the projections is preferably 50 to 35,000 per 1 cm ² of the surface of the support. If the number is less than 50 per 1 cm ² , the cut edge when cut by hand may not be straight, and the strength of the obtained film may be reduced. 1cm ²
It is difficult to make more than 35,000 pieces per production method. The arrangement pattern of the protrusions 5 is preferably a so-called grid pattern as shown in FIG. 5, that is, the thermoplastic resin film (so that the protrusions in one row are sandwiched between the protrusions in the adjacent row). a) parallel to the flow direction (longitudinal direction) or along the width direction. In FIG. 5, the interval between the protrusions 5 is uniform in the flow direction and the width direction. However, as shown in FIG. 6, the interval in the flow direction may be wider than the interval in the width direction. In short, any pattern may be used as long as the protrusions 5 are arranged in the direction in which the hand-cutting property is desired.

As the thermoplastic resin layer 3 to be laminated on the side of the protrusion, a polyolefin resin such as low-density polyethylene, high-density polyethylene, polypropylene or the like, a mixture of polyolefin resins, a polyester resin, or the like is used. Which may be the same or different from the projections. However, if the thermoplastic resin layer 3 is not in close contact with the protrusions 5, the thermoplastic resin layer 3 and the protrusions 5 are separated at the time of hand cutting, and stress is not concentrated between the protrusions. The hand-cutting property will be reduced. Therefore, it is preferable that the resin forming the thermoplastic resin layer 3 has high adhesion to the resin forming the protrusions 5. For example, when the resin forming the protrusions 5 is a polyethylene-based resin, the resin forming the thermoplastic resin layer 3 is also preferably a polyethylene-based resin or an ethylene-based copolymer resin.

The thickness of the thermoplastic resin layer 3 is
It is sufficient that the air layer 6 is left between the protrusion and the protrusion 5, and the vertex of the protrusion may be completely covered. Is fine. The total volume of the air layer 6 is 5 to 5 with the sum of the total volume of the air layer and the total volume of the projections being 100% by volume.
It is 95%, preferably 10-90%. If it is less than 5% by volume, it does not contribute to the improvement of the hand-cutting property, and if it is more than 95% by volume, the strength of the whole film decreases.

The laminated film of the present invention having the above structure can be manufactured, for example, as follows. First, a thermoplastic resin film 2 in which projections are arranged integrally on a support is manufactured. This thermoplastic resin film 2 can be manufactured, for example, as shown in FIG. That is, the raw material 7 of the thermoplastic resin is supplied to the extruder 8, and the resin that has been heated and melted passes through the die 9,
It is supplied to the rotating circular mold 10. A cavity 11 is provided on the circular surface of the mold 10, and molten resin flows into the cavity 11 to form a projection. At this time, the space between the die and the mold is sealed, and the cavity 11 is closed.
Is preferably exhausted by the external pressure reducing system 12. Then, since the cavity 11 is evacuated, the molten resin flows into the cavity 11 rapidly, and the resin is molecularly oriented in the flowing direction. By cooling the mold (cooling means is not shown), the orientation of the resin is fixed, and the strength of the protrusion is improved. Finally, the solidified resin is separated from the mold 10 by the peeling roller 1.
3, the projections 5 on the support 4
Are linearly arranged to obtain a thermoplastic resin film 2.

According to this method, for example, as shown in FIG. 3, using a sheet having a two-layer structure of a soft resin 14 and a hard resin 15 for a mold 10, and forming a projection with the mold shown in FIG. Also, a two-layer structure of the soft resin 14 and the hard resin 15 can be formed on the protrusion.

The laminated film of the present invention can be obtained by laminating a thermoplastic resin of the same type or a different type from the thermoplastic resin constituting the thermoplastic resin film on the thermoplastic resin film having the protrusions thus produced. This lamination can be performed using various methods. For example, as shown in FIG. 4, the thermoplastic resin 3 is hot-melt extruded from the extruder 16 onto the protrusion side of the thermoplastic resin film 2 having protrusions. In this case, a method of directly extruding is preferred. This laminating step can be performed continuously to the above-mentioned step of producing a thermoplastic resin film having a projection.

At the time of this lamination, the air layer is left without filling the space between the protrusions with the thermoplastic resin. Therefore, the melt flow rate of the thermoplastic resin to be laminated is preferably 20 g / 10 minutes or less. If the melt flow rate is higher than this, the fluidity is high and the space between the projections is filled without leaving an air layer.

As described above, the laminated film of the present invention is obtained. An adhesive tape can be obtained by using this film as a substrate and applying an adhesive on at least one surface. The pressure-sensitive adhesive is not particularly limited, but it is preferable to use, for example, an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a polyolefin-based pressure-sensitive adhesive, or the like. As a method of applying the adhesive, a general knife coater or a reverse coater is used to apply an adhesive solution or a dispersion, and a solvent is volatilized in a drying furnace, or hot melt extrusion is performed by an extruder. Is preferred. Also,
The coating thickness of the adhesive is preferably from 10 to 200 μm.

[0019]

EXAMPLES Example 1 Low-density polyethylene resin (melt flow rate 20 g / 10
Min, density 0.919) and hot melt extrusion at 230 ° C.
A mold having approximately 380 fine holes per cm ² was injected into the cavity while rotating. Removing the solidified resin from the mold, as shown in FIG. 5, 1 cm on the surface ²
Approximately 380 upstanding projections 5 per line form a so-called cross-cut film 2 that is linearly and continuously arranged in the production flow direction of the film and in the width direction perpendicular to the flow direction. Was done. The height of this projection is 300 μm
The thickness of the support was 80 μm.

On the surface of the film where the projections are arranged,
An ethylene-vinyl acetate copolymer resin (melt flow rate 2 g / 10 min, density 0.920) was laminated by melt extrusion at 230 ° C. to obtain a laminated film having a thickness of 380 μm. The thickness of the laminated ethylene-vinyl acetate copolymer resin was 45 μm. Observation of the cross section of the thus obtained laminated film with an optical microscope reveals that an air layer exists between the surface on which the protrusions are arranged and the ethylene-vinyl acetate copolymer resin layer laminated thereon. And the ratio of the air layer to the sum of the volumes of the projections was 70% by volume.

Examples 2 to 4 A laminated film was produced in the same manner as in Example 1, except that the resin shown in Table 1 below was used as the resin to be laminated on the film having the projections. Regarding the laminated films produced in Examples 1 to 4, the trigger and the shape of the cut when cut by hand from the end of the film in the width direction were all good, and the hand-cutting property was excellent. The tensile strength and elongation of these films were measured by a conventional method. Table 1 shows the results.

[0022]

[Table 1]

As described above, it is possible to arbitrarily set physical properties such as tensile strength in the flow direction and elongation at break depending on the combination of resins, and to obtain a film excellent in hand cutting property having physical properties according to the application. Obtainable.

Comparative Example A laminated film was produced in the same manner as in Example 1 except that the ethylene-vinyl acetate copolymer resin was completely laminated without completely filling the space of the projections and leaving an air layer. When the cross section of this film was observed with an optical microscope, there was no air layer between the surface where the protrusions were arranged and the ethylene-vinyl acetate copolymer resin layer laminated thereon, and the film was cut by hand in the width direction. In this case, the cut was not parallel to the width method, and the hand cutting property was poor.

[0025]

In the laminated film of the present invention, the projections are arranged in a predetermined pattern by being integrated with the support, and an air layer exists between the projections. Since the parts are connected by the resin layer interposed between them, the stress is more concentrated on the base between the protrusions when cutting by hand than when the unevenness is provided by simple embossing in the past Then, it can be easily and linearly cut between the projections, that is, along the arrangement of the projections. Further, since the resin layer is provided between the projections, the tensile strength of the film is not impaired. As described above, the laminated film of the present invention is particularly useful as a base material of a masking tape for architectural curing because it has excellent hand-cutting properties and can be cut linearly in a predetermined direction.

[Brief description of the drawings]

FIG. 1 is a sectional view of a laminated film of the present invention.

FIG. 2 is a view showing a process of manufacturing a film having a projection used for the laminated film of the present invention.

FIG. 3 is a cross-sectional view of a film having a protrusion used for the laminated film of the present invention.

FIG. 4 is a view showing a manufacturing process of the laminated film of the present invention.

FIG. 5 is a top view of a film having a projection used for the laminated film of the present invention.

FIG. 6 is a top view of a film having a projection used for the laminated film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laminated film 2 ... Protrusion film 3 ... Thermoplastic resin layer 4 ... Support 5 ... Protrusion 6 ... Air layer 7 ... Supply material 8, 16 ... Extruder 9 ... Die 10 ... Mold 11 ... Cavity 12 ... external pressure reducing system 13 ... peeling roller

Continued on the front page (72) Inventor Tomoaki Uchiya 3-8-8 Minamihashimoto, Sagamihara-shi, Kanagawa Prefecture Sumitomo 3M Corporation (72) Inventor Kazuki Sato 3-8-8 Minamihashimoto, Sagamihara-shi, Kanagawa Prefecture Sumitomo 3M Corporation F-term (Reference) 4F100 AK01A AK01C AK06 AK68 AT00C BA03 BA07 BA10A BA10C DD06A DD22B EA021 EH171 EH172 EJ192 EJ401 EJ931 GB71 JB16A JB16C JK03 4J004 AA05 AA07 AA10 AB01 CA04 CA02 CC03 GA05

Claims (4)

[Claims] 1. A thermoplastic resin film comprising a support of a thermoplastic resin and a plurality of projections arranged on one surface of the support in a predetermined pattern integrally with the support. And (b) a surface on which the protrusions of the thermoplastic resin film are arranged, comprising a thermoplastic resin layer laminated so as to fill a gap between the protrusions and the protrusions, the thermoplastic resin A laminated film having an air layer between the surface of the support between the projections of the film (a) and the thermoplastic resin layer (b). 2. The laminated film according to claim 1, wherein the thermoplastic resin film (a) and the thermoplastic resin layer (b) are formed of the same type of thermoplastic resin. 3. The laminated film according to claim 1, wherein the thermoplastic resin film (a) and the thermoplastic resin layer (b) are formed of different thermoplastic resins. 4. A pressure-sensitive adhesive tape comprising the laminated tape according to claim 1, and a pressure-sensitive adhesive layer on a surface of the thermoplastic resin film (a) opposite to a surface on which the protrusion is provided.