JP2909370B2 - Insulating tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating tape used for electric wiring of electric, electronic equipment, automobiles and the like, or for indoor and outdoor wiring at home.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 2, an insulating tape is formed on a polyester film 3 serving as a base material of the tape.
The film 3 is provided with an adhesive layer 4.
The structure is such that an anchor coat layer 5 made of an anchor coat agent is provided between the adhesive layer 4 and the adhesive layer 4 in order to enhance the adhesion between them. When it becomes necessary to impart flame retardancy to the insulating tape, a flame retardant is usually added to the adhesive layer 4. This insulating tape is used for electrical wiring parts such as electric, electronic equipment or automobiles, or indoors for home use.
It is used as a constituent material of a flat electric wire such as an outdoor wiring for covering and insulatingly protecting the electric wire. Further, the tape having such a configuration is used as an industrial tape in various applications other than the above.

As the insulating tape, there is a tape using a thermosetting polyester, a thermoplastic polyester, or a polyolefin adhesive, depending on the type of the adhesive layer 4. Above all, an insulating tape using a thermosetting polyester-based adhesive has been awarded for its excellent adhesiveness and buckling resistance. However, this insulating tape has a drawback that it is difficult to handle in terms of management because curing proceeds at room temperature. That is, there is a case where the bonding is not performed even when the laminating process is performed using the thermosetting polyester-based adhesive after the passage of time. In addition, a step of heat treatment (oven curing) is required to complete the bonding, and there is a problem that the step becomes long. Furthermore, since it is necessary to dissolve the adhesive resin in a solvent and apply it to the base film, there is a problem that the loss increases and the cost is increased because the raw materials are expensive.

On the other hand, an insulating tape using a thermoplastic polyester-based adhesive is also excellent in buckling resistance and has an advantage that it is not cured at room temperature and is easy to handle in comparison with a thermosetting type. . However, as in the case of the above-mentioned thermosetting type, it is necessary to dissolve in a solvent for coating, and there is a disadvantage that the cost is high since the raw materials are expensive.

Further, polyester-based adhesives of both thermosetting and thermoplastic types have properties such as high wettability of the resin surface with water and high water absorption of the resin itself, and are inferior in long-term water resistance. For this reason, severe evaluation such as heat aging in the state where the insulating tape using a thermosetting or thermoplastic polyester adhesive is folded, then restoring the shape and conducting a withstand voltage test in salt water Is disadvantageous in that insulation is poor and the withstand voltage characteristics are inferior.

On the other hand, an insulating tape using a polyolefin-based adhesive as the above adhesive has inferior adhesive and buckling characteristics as compared with an insulating tape using a polyester-based adhesive, but is hardened at room temperature. And has the advantage of being the least expensive. However, the insulating tape using the polyolefin adhesive also has a disadvantage that the withstand voltage characteristics are inferior as in the case of the polyester-based adhesive.

[0007]

As described above, an insulating tape using a polyolefin adhesive as an adhesive has properties such as poor adhesiveness, buckling resistance and withstand voltage characteristics. Therefore, when this insulating tape is used for electric wiring under severe conditions such as an electric system part of a car and outdoor wiring for home use, the flat wire buckles and deforms due to a physical impact, and a failure such as disconnection occurs. The problem arises. In addition, when the flat electric wire is bent and used for a long period of time, problems such as partial peeling and cracking occur. However, insulating tapes using polyolefin adhesives
As described above, the cost is significantly lower than insulating tapes using other adhesives, and it is easy to handle in terms of management without heat curing at room temperature. There is a strong need to raise it to be practical.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an insulating tape having excellent adhesion, buckling resistance, and withstand voltage characteristics at low cost.

[0009]

In order to achieve the above object, the present invention provides a method for forming an anchor coat layer containing an organotitanium compound as a main component on a film surface of a polyester film. In which a polyolefin-based adhesive layer is formed.

[0010]

In other words, to solve the above-mentioned problems, the present inventors first studied the problems of adhesiveness and withstand voltage characteristics of the insulating tape. As a result, the inventors have found that the above-mentioned problem is not caused by the polyolefin-based adhesive layer itself, but is caused by the urethane-based anchor coat layer conventionally used. That is, the problem of the withstand voltage characteristics is caused by a slight lifting and peeling between the urethane-based anchor coat layer and the adhesive layer when the shape is restored after the insulating tape is folded. Thus, it has been found that when an anchor coat layer is formed by using an anchor coat agent containing an organic titanium compound as a main component instead of the urethane-based anchor coat layer, the adhesion and the withstand voltage characteristics are improved. Furthermore, the problem of buckling resistance was examined. As a result, they found that the problem of buckling resistance was caused by insufficient rigidity of the adhesive layer due to the use of a flexible polyolefin-based adhesive in consideration of the adhesiveness to the base film. Then, in order to solve the insufficient rigidity of the adhesive layer, the above-mentioned polyolefin-based adhesive layer was examined. As a result, it has been found that if the flexural modulus of the polyolefin-based adhesive layer is set to 500 to 20,000 kg / cm ² , the problem of buckling resistance can be solved and the withstand voltage characteristics can be further improved. Further, even if a flame retardant for imparting flame retardancy to the adhesive layer is blended,
It was confirmed that there was no effect on each characteristic. With this invention,
It is possible to provide a low-cost insulating tape which is excellent in adhesiveness, buckling resistance, and withstand voltage characteristics and has flame retardancy as required.

Next, the present invention will be described in detail.

The insulating tape of the present invention is obtained by using a polyester film, an anchor coating agent containing an organic titanium compound as a main component, and a polyolefin adhesive.

The polyester film serving as a base material of the insulating tape is not particularly limited, and a conventionally known polyester film is used. And, from the viewpoints of durability, flexibility and electrical insulation, the thickness is usually 0.012 to
It is set in the range of 0.2 mm. Preferably, 0.02
The range is 5 to 0.1 mm.

The anchor coating agent contains an organic titanium compound as a main component. As the organic titanium compound, an alkyl titanate represented by the following general formula can be used.

Ti (OR) ₄ [In the above formula, R is an alkyl group or an allyl group. ]

Such alkyl titanates include:
For example, the following compounds are mentioned, and they are used alone or in combination.

Tetra-i-propyl titanate [Ti
(OiC ₃ H ₇ ) ₄ ], tetra-n-butyl titanate [Ti (On-C ₄ H ₉ ) ₄ ], tetra (2-ethylhexyl) titanate {Ti [OCH ₂ CH (C ₂
H ₅₎ C ₄ H _{9] 4},} tetrastearyl titanate [Ti (OC ₁₈ H _{37) 4].}

An anchor coat layer using the above anchor coat agent is a colorless, transparent and very thin high molecular weight titanium oxide having a structure similar to titanium oxide (TiO ₂ ) because the —OR group in the molecule is dissociated by a hydrolysis reaction. It becomes a film. Its thickness is set in the range of 0.0005 to 10.0 μm, preferably in the range of 0.001 to 2.0 μm.

Examples of the polyolefin adhesive include high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (L-PE).
Resins such as LDPE), ultra-low density polyethylene, polypropylene (PP) and polymers thereof, and unsaturated carboxylic acids (acrylic acid, methacrylic acid, maleic acid,
A graft-modified product such as fumaric acid, itaconic acid, crotonic acid, citraconic acid, or an acid anhydride (maleic anhydride, itaconic anhydride, citraconic anhydride, etc.) can be used. Further, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMA)
A), a copolymer such as an ethylene-vinyl acetate glycidyl methacrylic acid copolymer (E-VA-GMA), a resin obtained by graft-modifying these resins with alkoxysilane, or an ionomer (ethylene-acrylate metal ion copolymer). And an ethylene-methacrylate metal ion copolymer) can be used.

The bending elastic modulus of the adhesive layer formed by using the above-mentioned polyolefin adhesive is 500 to 20,000 k.
g / cm ² , and more preferably 2500 to 10000 kg / cm ² . By setting the flexural modulus in the above specific range, the difference between the flexural modulus of the adhesive layer and the flexural modulus of the polyester film is reduced, and the buckling resistance is further improved. Also, the withstand voltage characteristics can be improved.

In the present invention, the flexural modulus is determined according to JIS.
It is measured by the method shown below with reference to the bending elasticity test method of K7203 hard plastic. That is, the polyolefin-based adhesive layer is 10 mm wide × 1 mm
A test sample is formed by hot pressing to a thickness of 80 mm length. Then, as shown in FIG. 8, the test sample 21 is placed on the two supports 20, and the pressure wedge 19 is lowered at a constant speed (5 mm / min), and the load-deflection curve at this time is recorded on a chart paper. Then, the flexural modulus is calculated by the following equation. In FIG. 8, L indicates the distance between the fulcrums of the two support bases 20.

E = L ³ / (4 × bh ³ ) × F / Y [where E is the flexural modulus (kg / cm ² ),
L is the distance between supports (cm), b is the width of the test sample (c
m) and h are the thickness (cm) of the test sample, and F is the load (k) at an arbitrarily selected point on the first straight line portion of the load-deflection curve.
gf) and Y represent the amount of deflection (cm) at the load F, respectively. ]

When it becomes necessary to impart flame retardancy to the insulating tape of the present invention, its purpose can be achieved by adding a flame retardant to the polyolefin-based adhesive layer. Examples of the flame retardant include decabromodiphenyl ether, hexabromobenzene, tetrabromobisphenol A and derivatives thereof, brominated flame retardants such as pentabromobenzyl polyacrylate, chlorinated paraffin, perchlorocyclopentadecane, tetrachlorophthalic anhydride, chlorend Examples include chlorine-based flame retardants such as acids, inorganic fillers such as aluminum hydroxide and magnesium hydroxide, and phosphorus-containing flame retardants such as phosphate esters and halogen-containing phosphate esters. The proportion of the flame retardant is preferably set in the range of 20 to 250 parts with respect to 100 parts by weight of the polyolefin adhesive (hereinafter abbreviated as "part").
If necessary, a flame retardant aid such as antimony trioxide and zinc borate can be used in combination.

In addition to the above-mentioned flame retardants and flame retardant assistants, various additives conventionally used in polyolefin adhesive layers can be blended as required. Examples of these additives include inorganic fillers such as titanium dioxide, talc, and alumina, and antioxidants, copper damage inhibitors, and ultraviolet absorbers.

The insulating tape of the present invention can be produced by using the above-mentioned raw materials, for example, as follows.
That is, a pellet-like polyolefin-based adhesive is prepared. Then, a predetermined amount of an additive such as a flame retardant is blended with the adhesive pellets, kneaded using a twin-screw mixer, water-cooled, cut and pelletized again. On the other hand, the organic titanium compound is mixed with an organic solvent such as ethyl acetate, toluene, etc.
Prepare a ５5% by weight solution. This solution is applied to one surface of a polyester film by a commonly used roll coating method such as a gravure roll coating method or a reverse roll coating method, and the solvent is removed through a heating and drying oven to form an anchor coat layer. In addition, this coating method is not limited to the roll coating method, but may be performed by a spray coating method or the like. Then, on the anchor coat layer, the polyolefin adhesive previously pelletized is subjected to extrusion lamination processing by a T-die extruder or the like. Thus, an insulating tape having a three-layer structure as shown in FIG. 1 can be obtained. In the figure, 1 is a polyolefin-based adhesive layer, 2 is an anchor coat layer containing an organic titanium compound as a main component, and 3 is a polyester film.

[0026]

As described above, the insulating tape of the present invention has an anchor coat layer mainly composed of an organic titanium compound provided between a polyester film and an adhesive layer.
No urethane anchor coating agent is used. For this reason, it becomes possible to realize an improvement in the adhesiveness and withstand voltage characteristics of the insulating tape. Further, by setting the bending elastic modulus of the adhesive layer in a specific range, buckling resistance and withstand voltage characteristics are further improved, so that electric wiring under severe conditions such as an electric system part of an automobile and outdoor wiring. Buckling of the insulating tape due to physical impact does not occur, and accidents such as disconnection and poor insulation do not occur. Also,
When a flame retardant is blended in the adhesive layer, it is possible to prevent the spread of fire when the insulating tape of the present invention is applied to a flat electric wire or the like.

Next, examples will be described together with comparative examples.

[0028]

Examples 1 to 5 An insulating tape was produced as follows. That is, first, an anchor coat layer having a thickness of 0.1 μm was formed on the film surface of a polyester film having a thickness of 50 μm using alkyl titanate. On the other hand, the materials shown in Table 1 below were blended in the proportions shown in the same table, kneaded with a biaxial mixer, then water-cooled and cut to produce adhesive pellets. Then, the adhesive pellet is placed on the anchor coat layer of the polyester film by T
Extrusion lamination by die extruder and thickness 80μm
The intended insulating tape was obtained by forming the adhesive layer of the above.

[0029]

Comparative Examples 1 to 7 According to the above-mentioned method, the following Table 2
Then, the materials shown in Table 3 were blended in the proportions shown in Table 3 to produce an insulating tape. In Comparative Examples 1 to 5, a 10 μm-thick anchor coat layer was formed using a modified EEA silane, and in Comparative Example 6 using a urethane anchor coat agent. In Comparative Example 7, no anchor coat layer was formed. Other than that, the target insulating tape was produced like Example.

Examples 1 to 5 obtained in this manner,
With respect to the insulating tapes of Comparative Examples 1 to 7, the withstand voltage characteristics, the adhesive strength to copper foil, and the buckling resistance were examined. The results are also shown in Tables 1 to 3 below. In addition, the said characteristic was investigated according to the method shown below.

[Withstand voltage characteristics] Two insulating tapes and 120
Using five copper wires having a thickness of 3 μm and a width of 3 mm, a lamination process was performed so that the distance between the wires was 1 mm, and a flat cable 18 as shown in FIG. 3 was produced and used as a test sample. 3A is a sectional view of the flat cable 18, and FIG. 3B is a plan view thereof. Then, the flat cable 18 is folded at a right angle as shown in FIG.
In this state, a heat aging treatment was performed at 100 ° C. for 120 hours. Then, it cooled to room temperature and restored to the original shape. Then, as shown in FIG. 5, the container 10 was filled with 5% saline 9 and the fold of the flat cable 18 was immersed in the saline 9. Then, using a DC power supply 7, a voltage of 1 kv was applied for 1 minute from the copper wire located at the side of the copper wire 6. Then, the voltage drop was measured by the voltmeter 8. That is,
If there is a gap between the copper wire 6 and the adhesive layer 1, the saline solution 9 penetrates into the gap, and the voltage drops. Therefore, the withstand voltage characteristics were represented by ○ when the voltage did not decrease, and by X when the voltage decreased. In addition, the appearance of the flat cable was also observed, and the case where there was no change was indicated by “○”, and the case where discoloration or cracks were observed was indicated by “×”.

[Adhesive Strength to Copper Foil] The adhesive layer of the insulating tape was rolled into a rolled copper foil (50 μm thick) by a heat roll laminating method.
m, untreated product). The lamination conditions at this time were a pair of three silicon rubber rolls having a diameter of 80 mm and a roll temperature of 175 ° C., a lamination speed of 0.5 mm / min, and a lamination linear pressure of 6.0 kgf / cm. Then, the obtained adhesive was cut into a width of 10 mm to obtain a test sample. Using a strograph (R-2 type, manufactured by Toyo Seiki Co., Ltd.), a speed of 50 mm / min.
A 0 degree peel test was performed to measure the peel strength between the copper foil and the insulating tape.

[Bucking resistance] Two insulating tapes were bonded by a heat roll laminating method under the same conditions as in the evaluation of the adhesive strength to copper foil so that the respective adhesive layers were in contact with each other. What was formed into a 50 mm width x 150 mm length was used as a test sample. Using this test sample, buckling resistance was evaluated using the above-mentioned strograph. That is, as shown in FIG. 6, the test sample 12 is disposed between the two support plates 14a and 14b, and is fixed with the tape 13. Then, a compressive force is applied by moving the support plate 14b in the direction of the arrow at a constant speed, and pressure is applied until the sample 12 is completely bent, and the load-compression distance curve at that time is recorded on a chart paper.
In FIG. 6, reference numeral 11 denotes a load cell. Also,
FIG. 7 shows an example of this load-compression distance curve. In FIG. 7, a curve 16 is a curve when there is no buckling,
A curve 15 is a curve when buckling occurs. In the case of buckling, a peak 17 appears on the curve 15. Therefore, in the evaluation of the buckling resistance, those in which this peak 17 did not appear were represented by ○, and those in which this peak 17 appeared were represented by x.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

From Tables 1 to 3, it can be seen that the insulating tapes of the examples are excellent in all of the properties of withstand voltage, adhesion to copper foil, and buckling resistance. In contrast, the insulating tapes of Comparative Examples 1 and 6 were inferior in buckling resistance, and the insulating tapes of Comparative Examples 4 and 7 were inferior in adhesiveness. All of the insulating tapes of Comparative Examples 1 to 7 were inferior in withstand voltage characteristics.
In addition, in the example product, the heat resistance (135 ° C.
× 7 days) and good water resistance (80 ° C. hot water × 7 days).

[Brief description of the drawings]

FIG. 1 is a sectional view of an insulating tape according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional insulating tape.

FIG. 3A is a cross-sectional view of a test sample used for measuring a withstand voltage characteristic, and FIG. 3B is a plan view thereof.

FIG. 4 is an explanatory diagram showing a folded state of an insulating tape in measurement of withstand voltage characteristics.

FIG. 5 is an explanatory diagram of a method for measuring withstand voltage characteristics.

FIG. 6 is an explanatory diagram of a method for measuring buckling resistance.

FIG. 7 is a curve diagram of a load-compression distance obtained in the measurement of the buckling resistance.

FIG. 8 is an explanatory diagram of a method for measuring a flexural modulus.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Polyolefin adhesive layer 2 Anchor coat layer mainly composed of an organic titanium compound 3 Polyester film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // C08J 7/04 CFD C08J 7/04 CFDE H01B 17/56 H01B 17/56 A (72) Inventor Ryuzo Asano Komaki, Aichi Prefecture Ogai Kitagaiyama character Gezu 3600 East Kai Rubber Industry Co., Ltd. (72) Inventor Naotoshi Miyahara Komaki city, Aichi prefecture Oki Kitagaiyama character Gezu 3600 East Kai Rubber Industry Co., Ltd. 8 Mitsushima Nishinocho, Mitsubishi Cable Industry Co., Ltd. (72) Inventor Masaaki Nagai 8 Nishiyuki Higashimushimajima, Amagasaki City, Hyogo Prefecture Inside Mitsubishi Cable Industry Co., Ltd. 8, Mitsubishi Electric Cable Industry Co., Ltd. (72) Inventor Hiroyuki Uebayashi, Mitsubishi Electric Wire Industry Co., Ltd., 58, Nishinocho, Higashimukaijima, Amagasaki City, Hyogo Prefecture Field (Int.Cl. ⁶ , DB name) H01B 17/56-17/66 H01B 3/16-3/56

Claims (2)

(57) [Claims] An anchor coat layer containing an organic titanium compound as a main component is formed on a film surface of a polyester film, and a polyolefin-based adhesive layer is formed on the anchor coat layer. Insulating tape. 2. The insulating tape according to claim 1, wherein the flexural modulus of the polyolefin-based adhesive layer is set in a range of 500 to 20,000 kg / cm ² .