JPS5825709B2 - Nenchaku tape - Google Patents

Description

[Detailed description of the invention] The present invention relates to adhesive tapes.

More specifically, the object is to provide an adhesive tape that is easy to cut.

Adhesive tapes are widely used for household, commercial, and industrial purposes.

Cellophane is used in large quantities as a base film for adhesive tapes.

Cellophane has excellent transparency, smoothness, low elongation at break,
It has easy-to-use properties such as easy cutting ability, and also has mechanical strength suitable for many types of support and packaging.

However, cellophane has the disadvantage that if stored for a long period of time, it will deteriorate under the influence of sunlight or a low-temperature atmosphere, becoming brittle or poor.

Furthermore, depending on the application, there are fields that require dimensional stability, temperature stability, chemical resistance, abrasion resistance, and water resistance, but cellophane cannot satisfy these conditions.

The inventor of the present invention maintains the transparency, mechanical strength, smoothness, easy cutting properties, etc. that cellophane tape has, and also maintains the dimensional stability, temperature stability, chemical resistance, abrasion resistance, etc., which are the disadvantages of cellophane tape. As a result of intensive research into adhesive tapes with excellent chemical, physical, mechanical, and thermal properties such as water resistance, we found that the base film for adhesive tapes has an intrinsic viscosity of 0.3.
The inventors have discovered that such demands can be met by using a biaxially oriented polyethylene terephthalate film with a thickness of 5 or more and 0.58 or less and a thickness of 28μ or less, and have thus arrived at the present invention.

That is, the present invention has an intrinsic viscosity of 0135 or more and 0.58 or less, a thickness of 28μ or less, a refractive index in the longitudinal direction (longitudinal direction of the film) of 1.629 to 1.694, and a transverse direction ( This adhesive tape is characterized in that an adhesive is applied to at least one side of a biaxially oriented polyethylene terephthalate film having a refractive index of 1.632 to 1.694 (in the width direction of the film).

The polyethylene terephthalate referred to in the present invention includes not only non-copolymerized polyethylene terephthalate and homopolymers, but also copolymerized polyethylene terephthalate in which the number of repeating units is 85 molar or more ethylene terephthalate units, and the remainder is other components. or polyethylene terephthalate on an 85-weight plate (preferably a 90-weight plate)
15 weight parts or less (preferably 10 weight parts or less) of other polymers.

Examples of polymers that can be blended include polyamides, polyolefins, and other types of polyesters.

In addition, the polyethylene terephthalate may be added with a lubricant or
It may contain a matting agent, a coloring agent, a stabilizer, a plasticizer, an ultraviolet absorber, an antioxidant, an antistatic agent, and the like.

The polyethylene terephthalate film used as the base of the adhesive tape of the present invention must be biaxially oriented, have an intrinsic viscosity of 0.35 or more and 0.58 or less, and have an average thickness of 28μ or less. It won't happen.

If the intrinsic viscosity of the film is lower than 0.35, it will be difficult to stretch the film and breakage will occur frequently, and the resulting film will also have low mechanical strength, and when used as an adhesive tape, it will be difficult to cut the film. Tears may appear in directions unrelated to the direction (usually the horizontal direction), or when attempting to peel and cut the required length from a rolled up adhesive tape, the tape may not be peeled off cleanly and a portion may tear off. There are many problems such as the tape remaining on the tape that was wound inside, which is not desirable in practice.

Further, if the intrinsic viscosity is higher than 0.58, film formation is easy, but the cutting strength of the tape is too high, making it difficult to cut, which is not preferable.

Moreover, if the film thickness (average thickness) is greater than 28 μm, the cutting strength of the adhesive tape becomes too high, which is not preferable.

The film has an intrinsic viscosity of 0.38 to 0.56, especially 0.38 to 0.56.
41 to 0.54 is preferred.

Also, if the thickness of the film is too thin, the waist will become weak,
Static electricity can cause the adhesive tape to cling to your hands, and the adhesive tape itself tends to curl up.
The thickness of the film is preferably 12μ or more, particularly preferably 12 to 25μ.

It is best to set it to 15-23μ.

The film for the adhesive tape base used in the present invention is made of, for example, an unstretched polyethylene terephthalate film (with an intrinsic viscosity of 0.35 to 0.58) melt-extruded at a normal extrusion temperature (260 to 280°C), and uniaxially stretched ( After longitudinal stretching or transverse stretching), the film is further stretched in a direction perpendicular to the stretching direction (if the stretching is in the longitudinal direction, then in the transverse direction).

The stretching conditions are, for example, stretching temperature (both vertical and horizontal) from SO to 110
°C (However, it does not have to be the same warm concubine both vertically and horizontally.

), stretching magnification 2.5 to 4.5 times (however, the magnification does not have to be the same both in length and width).

) and sequentially biaxially stretched vertically and horizontally at 200-240°C for 5-30°C.
Obtained by heat fixing for seconds.

The transverse stretch ratio is preferably 1.5 times or less than the longitudinal stretch ratio, and particularly preferably the transverse stretch ratio is 1.3 times or less (more preferably 1.2 times or less) than the longitudinal stretch ratio.

The stretching ratio in the machine direction may be larger or smaller than that in the transverse direction.

The density of the obtained biaxially oriented film varies slightly depending on the stretching conditions and heat setting conditions, but it is usually 1.397 to 1.
．． It is 415g/-.

However, the polyethylene terephthalate film used in the present invention is not limited to only those produced by such a method.

The biaxially oriented film used in the present invention has a longitudinal refractive index n
x and the refractive index n in the lateral direction satisfy the following equation.

1.629 < n x < 1.694 1.632 < n < 1.694 In particular, ny n x is -0,062≦n, -nx≦0.065 In particular, -0,058<n -n < 0.060 most preferably −0,054<n −n <0.054= y
It is better to be X-.

A polyethylene terephthalate film that satisfies the above requirements is used as a base film, and one or both sides of the film are subjected to surface activation treatment such as corona discharge treatment as necessary, and then treated with an anchor coating agent or back surface treatment as necessary. The adhesive adhesive 7'-bs of the present invention can be obtained by applying an adhesive, an adhesive, etc., and then slitting this into a tape shape.

Any known adhesive may be used for producing the adhesive tape of the present invention.

For example, rubber-based, vinyl ether-based, acrylic polymers, etc. may be used, and hot-melt adhesives may be used.

As a coating method, a method such as coating and drying an organic solvent solution or emulsion may be used, or a melt-extrusion lamination of something such as ethylene-vinyl acetate copolymer may be used as an adhesive.

The adhesive may be applied to one side, but when producing a double-sided adhesive tape, it may be applied to both sides.

An adhesive may be applied to one side, and a silicone-based mold release agent may be applied to the other side.

However, the adhesive type, application method, etc. are not limited to these.

The adhesive tape of the present invention has practical mechanical strength of dust so that it will not easily break due to a slight shock during use, has cutting properties comparable to cellophane tape when cut with a tape cutter, etc., and is transparent and smooth. This adhesive tape also has excellent chemical, physical, thermal, and mechanical properties such as dimensional stability, temperature stability, chemical resistance, abrasion resistance, and water resistance.

Therefore, it can not only be used in a wide range of applications similar to cellophane tape, but also can be used for packaging, exterior packaging, electrical insulation, etc. by taking advantage of its excellent water resistance.

Below, methods for measuring the main physical properties used in the present invention will be shown.

1) Value measured at 35°C using intrinsic viscosity 0-40 phenol as a solvent.

Its unit is 100cc/g. 2) Thickness of the film The thickness is calculated by dividing the weight of the film by the product of the film surface area and the density, expressed in μ.

For tight fitting, use a mixed solvent of n-hepukun and carbon tetrachloride.
It is measured by the float-sink method at 5°C.

3) Absolute breaking strength Tensilon UTM-Dish-500 manufactured by Toyo Baldwin Co., Ltd.
Using a mold, at room temperature and relative humidity of 65%, the length is 5 cr.
A 771 original film with fL1 width of 1.8 was pulled at 1(1)00 coefficient/min, a load-elongation chart was prepared, and the force required to break the film at room temperature was expressed as an absolute value (k
g).

4) Cutting Strength Using the same equipment used to measure absolute breaking strength, at room temperature, and relative humidity and cold, the total length was 36 CrrL, and the width was 1.8 cfrL.
Set a commercially available tape cutter blade between fixing parts 1 and 4crIL of the original film (see Figure 1), fixing part 1.
Fix the film with
Absolute cutting strength expressed in kg when the film is cut by the cutter blade while moving at n.

5) Cutability test A 1.8 mm wide adhesive tape made of polyethylene terephthalate film coated with an adhesive was examined for cutability using a commercially available tape cutter with n = 10.

Comparing the force required to cut the tape with that of cellophane tape, ◎ is the one that is as easy as cellophane tape or easier, ○ is the one that requires a little more force than cellophane tape but can be cut without problems. Items that require considerably more force and are not easily cut are marked with an x.

6) Static electricity generation capacity test When static electricity is generated, the base film is strong and will not stick to your hands. ◎ It will stick to your hands or curl a little, but it is a practical problem. Items that are not present are marked with a ○, and items that have practical problems such as clinging to hands or curling are marked with an x.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these methods. Examples 1 to 7 and Comparative Examples 1 to 4 Polyethylene terephthalate having a predetermined intrinsic viscosity (see Table 1)・Dry the chips, melt-extrude them into a film using a conventional method, and stretch the unstretched film in the machine direction at a predetermined stretching ratio (see Table 1) at a temperature of 90'C, and in the transverse direction at a temperature of 1.
Sequential biaxial stretching at 10°C, 10°C at the specified temperature (see Table 1)
The film was heat-set for seconds to produce biaxially oriented films of various thicknesses.

On the other hand, for comparison, unstretched polyethylene terephthalate films having different intrinsic viscosities produced in the same manner as in the examples were sequentially stretched at a predetermined stretching ratio (see Table 1) at 90°C in the machine direction and 110°C in the transverse direction. The film was axially stretched and heat-set for 10 seconds at a predetermined temperature (see Table 1) to produce biaxially oriented films of various thicknesses.

Absolute breaking strength of these adhesive tape base films,
The cut strength is shown in Table 1 along with that of the cellophane tape (from which the adhesive has been removed).

After corona discharge treatment on both sides of these polyethylene terephthalate oriented films, one side is coated with a silicone-based mold release agent solution, the other side is coated with natural rubber and polyterpene resin as main components as adhesives, and process oil and aging are applied to the other side. A toluene solution (adhesive concentration: 25% by weight) containing an inhibitor was applied and dried in hot air at 90°C to obtain a log roll, which was slit into a width of 18 mm, similar to commercially available cellophane tape. A sensory test of cutting properties was conducted using this adhesive tape.

The results are shown in Table 1.

The refractive index in the longitudinal direction (nx), the refractive index in the transverse direction (n, ), and the refractive index in the thickness direction (n2) of the films of Examples 1 to 7 and Comparative Examples 1 to 3 are as follows. Ta.

[Brief explanation of drawings]

FIG. 1 is a diagram showing how to set a cutter blade and film when measuring cut strength.

Claims (1)

[Claims] 1 A single polymer yarn with an intrinsic viscosity of 0.35 or more and 0.35 or more.
58 or less, the thickness is 28μ or less, the refractive index in the vertical direction is 1.629 to 1.694, and the refractive index in the horizontal direction is 1.6-
Biaxial orientation between 32 and 1.694, -1-? I.J.
An adhesive tape characterized by having an ethylene terephthalate film coated with an adhesive on at least one side.