JPS6037838B2 - adhesive tape - Google Patents

Description

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

More specifically, it should be easy to cut and stick to your hands (
The present invention relates to an adhesive tape made by applying an adhesive to a biaxially oriented polyethylene terephthalate film that does not generate static electricity and has excellent printing ink adhesion, transparency, and slipperiness. 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 easy-to-use properties such as excellent transparency, smoothness, low elongation at break, and ease of cutting, as well as mechanical strength suitable for many supporting and packaging applications. However, cellophore 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, resulting in arm formation or yellowing. Depending on the application, dimensional stability, temperature stability, chemical resistance, abrasion resistance, and water resistance are required, but cellophane cannot satisfy these conditions. The present inventor maintains the transparency, mechanical strength, smoothness, easy cutting property, etc. of cellophane tape,
In addition, as a result of intensive research into adhesive tapes that have excellent chemical, physical, mechanical, and thermal properties such as dimensional stability, temperature stability, chemical resistance, abrasion resistance, and water resistance, which are disadvantages of cellophane, As already disclosed in Tokukan Sho 52-5614 Publication, if a biaxially oriented polyethylene terephthalate film with an intrinsic viscosity of 0.35 or more and 0.5a or less and a thickness of 28 or less is used as the base film of the adhesive tape. We have found that it is possible to meet such demands.

However, many adhesive tapes made of oriented polyethylene terephthalate film are printed, but when polyethylene terephthalate film is printed, the adhesion of ink during coating film formation is low. Static electricity is also likely to be generated, especially if the thickness of the film is made thinner in order to make it easier to cut, the stiffness becomes weaker, and the static electricity generated can cause the adhesive tape to cling to your hands, or cause the adhesive tape to stick to each other. This is not preferable because it tends to get tangled with other objects.
The present inventor has created an object that maintains the transparency, mechanical strength, smoothness, and easy-cutting property of cellophane tape, and compensates for the drawbacks of cellophane film and polyethylene terephthalate film as described above, as well as adhesion of printing ink. As a result of extensive research into adhesive tapes that have excellent properties and generate less static electricity, we found that they contain 0.5 to 1% polyethylene glycol with a molecular weight of 5,000 to 200,000, and have an intrinsic viscosity of 0.35 to 0.58. The inventors have discovered that such requirements can be met by using a biaxially oriented polyethylene terephthalate film having a thickness of 28 mm or less, and have thus arrived at the present invention.

That is, the present invention provides a two-bag oriented polyethylene terephthalate film containing 0.5 to 1% of polyethylene glycol with a molecular weight of 5,000 to 200,000, an intrinsic viscosity of 0.35 to 0.58, and a thickness of 28 mm or less. An adhesive tape with an adhesive coated on at least one side.

The base film of the adhesive tape of the present invention is characterized in that the wetting angle with water is 25 to 55 degrees. 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 85 mol% or more of the number of repeating units consists of ethylene terephthalate units and the remainder is other components. or polyethylene terephthalate in an amount of 85% by weight or more (preferably 90% by weight)
or more) and the other polymers account for 15% by weight or less (preferably 1% by weight or less).

Examples of polymers that can be blended include polyamide, polyolefin, and polyester. In addition, the polyethylene terephthalate may be added as a flooring agent, a matting agent,
It may contain colorants, stabilizers, plasticizers, ultraviolet absorbers, antioxidants, and the like. The polyethylene terephthalate used as the base for the adhesive tape of the present invention is polyethylene glycol with a molecular weight of 5,000 to 200,000.
．． It contains 5 to 1 t% of skin.

The molecular weight of the polyethylene glycol used in the present invention is 5,000 to 200,000, preferably 8,000 to 150.
000, more preferably 10,000 to 100,000.

The one with a large molecular weight is called polyethylene oxide, but the repeating unit is HotCH2-CH2
It is a polyenal expressed as 1○nan nH. Moreover, the content with respect to polyethylene terephthalate is 0.5 to 10.
Skin t%, preferably 2.1-5. Skin t%, more preferably 2.5-4. It is 9%. Polyethylene glycol with a molecular weight of less than 500 degrees has insufficient adhesion to printing ink even if the additive concentration is considerably increased, and a large amount of static electricity is generated. On the other hand, for those with a molecular weight of 200,000 or more, if polyethylene glycol is added to increase the adhesion of the printing ink, the base film will be
Transparency is compromised. If the content of polyethylene glycol is too low, such as 0.5 wt% or less, the adhesion to printing ink will not be sufficiently high, and a large amount of static electricity will be generated. On the other hand, the content is 10. If the amount is too high (more than skin t%), the haze of the film will be high, the transparency will be impaired, and the original excellent properties of the polyethylene terephthalate film will be impaired. The polyethylene terephthalate film used as the base of the adhesive tape of the present invention contains polyethylene glycol and is biaxially oriented, and has an intrinsic viscosity of 0.35 or more and 0.58 or less, and a thickness (average) of 2
Must be 8#m or less.

If the intrinsic viscosity of the film is lower than 0.35, the stretching of the film will be difficult and breakage will occur frequently, and the resulting film will also have low mechanical strength, so that when it is used as an adhesive tape, when trying to cut it, Tears may also occur in directions unrelated to that direction (usually the horizontal direction), or when trying to peel off 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, causing the inside There are many problems such as the tape remaining on the tape that was wrapped around it, which is not practical. Further, if the intrinsic viscosity is higher than 0.58, film formation is easy, but the cutting strength of the tape is too high and it becomes difficult to cut, which is not preferable. Also, if the thickness (average) of the film is greater than 2.81 m,
This is not preferable because the cutting strength of the adhesive tape becomes too high. The film has an intrinsic viscosity of 0.38 to 0.56,
Particularly preferred is 0.41 to 0.54.

Although there is no particular limit to the lower limit of the film thickness, with adhesive tapes based on ordinary polyethylene terephthalate film, as described in Mochiseki Publication No. 52-5614, if the film thickness is too thin, it will cause problems. This can cause the adhesive tape to cling to your hands due to static electricity, or the adhesive tape itself to tend to curl up.
The thickness of the film is preferably 12 m or more, but with the adhesive tape based on the polyethylene terephthalate oriented film of the present invention, even if the thickness of the film is made thinner and the stiffness becomes weaker, it is still possible to prevent static electricity. Since the amount generated is small, the adhesive tape does not get stuck to the hand or the adhesive tape itself curls, making it easy to handle.

Furthermore, by making the film thinner, it is possible to obtain an easily cuttable adhesive tape. The lower limit of the film thickness is not particularly limited, but it is preferably about 6 French m, and the film thickness is particularly preferably 8 to 23 French m, and 10 to 21 French m.
It is best to make it Buddha m. In order to impart adhesion between the biaxially oriented polyester film, which is the base of the adhesive tape of the present invention, and the printing ink, the wetting angle between the film and water is preferably 25 to 55 degrees, preferably 30 to 48 degrees. .

Whether the water wetting angle is 25 degrees or less or 55 degrees or more, the adhesion of the printing ink is poor and undesirable. In producing the film of the present invention, the polyethylene glycol component may be added at any time before the polymerization of polyethylene terephthalate is completed, but it is convenient to add it after transesterification. However, it is not particularly limited. In the present invention, there is a method of polymerizing a polymer having a predetermined polyethylene IJ coal content from the beginning. A high concentration master polymer is polymerized in advance, and this is mixed and diluted with polyethylene terephthalate polymer to a predetermined concentration using a blender. , a method of forming a film, and a method of adding a master polymer with a high concentration of polyethylene glycol immediately before forming a polyethylene terephthalate polymer into a film, but a combination of these methods is also possible.

When mixing the polymers, or beforehand, one or
There is no problem in incorporating suitable additives such as ultraviolet absorbers, lubricants, pigments, antioxidants, etc. into both polymers. The method for producing the polyethylene terephthalate film for adhesive tapes used in the present invention is not particularly limited, but the above-mentioned polyethylene glycol-containing polymers or mixtures with polyethylene terephthalate polymers can be produced using ordinary polyester film forming methods such as T-die. method, inflation method, etc., for example, at a normal extrusion temperature (260~
Melt extruded at 2800C) with an intrinsic viscosity of 0.35-0.
The unstretched film of No. 58 is uniaxially stretched (longitudinally or transversely stretched) and then 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 temperature can be almost the same as that for polyethylene terephthalate film, but there is no problem in stretching at a temperature changed depending on the content of polyethylene glycol. The stretching temperature is usually 70 to 100 oo. Stretching ratio is 2.5
~4. Needle sound (However, the magnification does not have to be the same both vertically and horizontally.)
It is obtained by sequentially biaxially stretching the longitudinal axis at , and heat-setting at 190 to 240 q○ for 5 to 3 papermaking periods. The transverse stretch ratio is preferably 1.3 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 lower) 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 is usually about 1.390 to 1.410 g/.
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 preferably has a longitudinal refractive index nx and a transverse refractive index ny that satisfy the following formula.

1.629SnXSI. 694 1.632≦ny≦1.694 In particular, ny−nx is −0.062≦ny−nXSO. 065 Especially -0.058≦ny-nxSO. 060 most preferably -0.054≦ny-nxSO. 054 is better.

A polyethylene terephthalate film that satisfies the above requirements is used as a base film, and one or both sides thereof are subjected to surface activation treatment such as corona discharge treatment as necessary,
Next, an anchor coating agent or a back treatment agent or the like is applied as necessary, and an adhesive or the like is further applied, and then the adhesive tape of the present invention is obtained by 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. For the coating method, methods such as applying and drying an organic solvent solution or emulsion may be used, or ethylene-
A melt extrusion laminate of a material such as a 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 to the extent 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 has transparency and smoothness. It has excellent chemical, physical, thermal, and mechanical properties such as no static electricity generation, excellent printing ink adhesion, dimensional stability, temperature stability, chemical resistance, abrasion resistance, and water resistance. This adhesive tape has both excellent performance.

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 Intrinsic viscosity 0-Value measured at 35qo using chlorophenol as a solvent.

Its unit is 100cc'g. 2 Thickness and Density of the Film The thickness is calculated by dividing the weight of the film by the product of the film surface area and density, expressed in French meters.

The density was determined by using a mixed solvent of n-hebutane and carbon tetrachloride.
500 by the flotation method.

3 Absolute shearing strength Using a tension UTM-m-50 mold manufactured by Toyo Baldwin Co., Ltd., at room temperature and relative humidity of 65%, an original film with a length of 5 cm and a medium thickness of 1.8 mm was pulled at a speed of 100 min. A load-elongation chart was prepared and the force required to break the film at room temperature was expressed as an absolute value (k9).

4. Cut strength The device shown in the drawing was attached to the tensile testing machine used for the absolute breaking strength, and the cut strength of the adhesive tape was measured at room temperature and relative humidity of 65°C.
Measured in an atmosphere of %.

Fix one T end of the original film with a total length of 36 mm and a medium thickness of 1.8 mm to the fixing part 1 so that the end is horizontal, and from the fixing part 1 to the L
= A commercially available tape cutter blade 3 (blade angle of 60 degrees) is fixed at a position 4 distances apart, and the fixing part 2 is cut through two free rollers 4 and 5 so that the rest of the film tape is in the vertical direction. Fixed to. The fixed part 1 at one end of the tape touches the cutter blade and the angle it makes with the free roller 4 is 130.
(The outer periphery of the free roller 5 is directly below the fixed part 2.) The other end of the fixed film, fixed part 2, is moved upward by 1° using a tensile tester.
The absolute cutting strength (kg) is measured when the film is cut by a cutter blade while moving at a speed of 0min. 5 Wetting angle of water The measurement film was left for one day and night at a constant temperature constant line with a temperature of 20 oo and a humidity of 60%, and then measured using a goniometer type contact angle measuring device manufactured by Elma Optical under the same temperature and humidity conditions.

The diameter of the water droplets was approximately 1 to 2 m'm.

The water used is distilled water. 6 Printing Ink Adhesive Tape Peeling Press Scotch Electrical Cutting Tape #56 at 19 h/m onto the printing ink coated surface and peel at 1000 ribs/m using a tensile tester.
The evaluation was made by performing a T-peel test at a speed of 1.5 in. to determine the peel strength.

7 Cutting property sensory test Cut the adhesive tape on the 18th side of polyethylene terephthalate film coated with adhesive using a commercially available tape cutter.
Cuttability was examined at =10.

Comparing the force required to cut the tape with that of cellophane tape, ◎ is similar to or easier than cellophane tape, and ◎ requires slightly more force than cellophane tape.
Those that can be cut without problems are marked with ○, and those that require considerably more force than cellophane tape and are not easily cut are marked with ×. 8 Static electricity generation sensory 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 there is no practical problem. ○ indicates that the material gets stuck to the hand or curls, causing problems in practical use.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these methods.

Examples 1 to 6, Comparative Examples 1 to 3 Polyethylene terephthalate was polymerized by a conventional method, and before the completion of polymerization, molecular weights of 4000, 6000, 20,000, 150,000, and 3 were determined according to each example.
After adding 2.9% of polyethylene glycol (0) and mixing, the mixture was discharged from a polymerization vessel and cut in a conventional manner to obtain a master polymer containing 2.9% of polyethylene glycol.

For comparison, a polyethylene terephthalate polymer was also prepared by a conventional method. This polymer was mixed and diluted with polyethylene terephthalate to have a predetermined polyethylene glycol content as shown in each example, melt-extruded into a film by a conventional method, and the unstretched film was stretched in the longitudinal direction at a temperature of 9000°C for 30 minutes. ．． Phrases, lateral stretching temperature 1
Sequential biaxial stretching of 4.1 times at 10 o'clock, 10 times at 23000
Heat setting was performed for seconds to obtain a film with a thickness of 12 mm.

Using cellophane ink (manufactured by Dainippon Ink; trade name CL-3709 (white)), apply cellophane ink to the obtained film so that the film thickness is approximately 2 mm, and
After drying for several minutes, a printing ink adhesion test was conducted. The results are summarized in Table 1. Table 1 The results show that the film of the present invention has excellent adhesion to printing ink and transparency.

Examples 7 to 13 Comparative Examples 4 to 7 Examples 7 to 13 were mixed and diluted in the same manner as Examples 1 to 6 and Comparative Examples 1 to 3 so that the content of polyethylene glycol with a molecular weight of 20,000 was 25%, and melted in the usual manner. The unstretched film is extruded into a film, and the unstretched film is sequentially stretched twice in the machine direction at a stretching temperature of 90 qo and in the transverse direction at a stretching temperature of 11,000 qo at a prescribed stretching ratio (see Table 2), and then stretched once at a prescribed temperature (see Table 1). It was heat-set with sand and made into biaxially directed films of various thicknesses.

On the other hand, in Comparative Examples 4 to 7, an unstretched film of the same polymer as in Examples 7 to 13 was prepared with
The film was sequentially stretched two times at a predetermined stretching ratio (see Table 2) at 10 oo, and heat-set for one time at a predetermined temperature (see Table 2) to obtain two-way oriented films of various thicknesses.

Absolute breaking strength of base film for these adhesive tapes,
Cut strength with cellophane tape (with adhesive removed)
It is shown in Table 2 along with that of .

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 polyterbene resin as main ingredients 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 9000C to obtain a log roll, which was slit into 18 pieces, similar to commercially available cellophane tape. A sensory test of the cutting properties was conducted using this adhesive tape.

The results are shown in Table 2. , 2...Refers to polyethylene terephthalate**
Cut strength. ...Cut strength (b9) when a cutter blade is inserted in the direction K at a right angle to the film's longitudinal direction.

*〉Hi* 34 (Comparative Example 7, stretched film thickness column)
......From the results of the thickness after peeling off the adhesive from the cellophane tape, the adhesive tape of the present invention has superior adhesion and transparency to printing ink, and the adhesive tape of the present invention is superior to the adhesiveness and transparency of printing ink, and the generation of static electricity when using the adhesive tape It is understood that this is an easily cutable film that does not get stuck to the hands.

[Brief explanation of drawings]

The drawing is a side view illustrating a method of measuring the cut strength of an adhesive tape.

Claims (1)

[Claims] 1 Contains 0.5 to 10 wt% of polyethylene glycol with a molecular weight of 5,000 to 200,000, and has an intrinsic viscosity of 0.3
An adhesive tape comprising a biaxially oriented polyethylene terephthalate film having a thickness of 5 to 0.58 and 28 μm or less, with an adhesive coated on at least one side. 2. The adhesive tape according to claim 1, wherein the wetting angle between the film and water is 25 to 55 degrees.