JPH06275157A - Insulating tape - Google Patents

Abstract

PURPOSE:To provide an insulating tape excellent in heat and water resistance or the like at low cost by laminating a layer of polyolefin adhesive on a polyester film via an anchor coating of silane modified polyolefin resin. CONSTITUTION:An anchor coating 2 of silane modified polyolefin resin is formed on the surface of a polyester film 3. As an example of the silane modified polyolefin resin, a resin obtained by graft copolymerization of alkoxysilane with an ethylene-ethyl-acrylate copolymer is mentioned. Next, a layer 1 of polyolefin adhesive (e.g. a layer of maleic acid modified low density polyethylene) is formed over the anchor coating 2 to manufacture an insulating tape. The silane modified polyolefin resin has so high affinity to both of the layers 1 and 3 and is so excellent in heat and water resistance that the layers 1 and 3 can be bonded together at a sufficient adhesion property and that the insulating tape excellent in heat and water resistance can be manufactured.

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 parts of electric and electronic devices or automobiles.

[0002]

2. Description of the Related Art Conventionally, as a constituent material for flat electric wires in electric wiring parts of electric and electronic devices or automobiles,
Insulating tape is used to cover and protect the wires. As shown in FIG. 2, this type of insulating tape has a structure in which an adhesive layer 5 is provided on a polyester film 3 which is a base material of the tape, and the adhesive layer 5 is provided between the film 3 and the adhesive layer 5. An anchor coat layer 4 is provided to enhance the adhesiveness between the two. Then, as the adhesive layer 5, one using a thermosetting adhesive, polyester adhesive, polyolefin adhesive or the like is commercially available. Above all, an insulating tape using a thermosetting adhesive is praised for its excellent heat resistance and water resistance. However, this insulating tape has a great drawback that it is difficult to handle in terms of management because the cost is high and curing proceeds at room temperature. Also, the insulating tape using a polyester adhesive has the advantage of being easier to handle in terms of management because it does not cure at room temperature as compared with the one using a thermosetting adhesive, but the thermosetting adhesive Like the above, the cost is high and the water resistance is poor. The insulating tape using the polyolefin-based adhesive as the adhesive layer is inferior in all properties of heat resistance and water resistance as compared with the insulating tape using the thermosetting and polyester adhesives,
It has the advantage that it does not cure at room temperature and is the cheapest.

[0003]

As described above, the insulating tape using the polyolefin adhesive as the adhesive has the property of poor heat resistance and water resistance. Therefore, when this insulating tape is used for electric wiring under severe conditions such as an electric system portion of an automobile, for example, there is a big problem that the insulating tape is thermally deteriorated or immersed in water. However, the insulating tape using the polyolefin adhesive has a significantly lower cost than the insulating tapes using other adhesives as described above, so that the heat resistance and the water resistance can be improved, and it can be put to practical use. There is a strong demand to do so.

The present invention has been made in view of such circumstances, and an object thereof is to provide an insulating tape which is inexpensive and has excellent heat resistance and water resistance.

[0005]

In order to solve the above-mentioned problems, the present invention is an insulating tape having a polyolefin adhesive layer laminated on a film surface of a polyester film, wherein a silane-modified polyolefin is present between the two. The resin anchor coat layer is formed.

[0006]

In order to achieve the above object, the present inventors have conducted a series of researches centering on an insulating tape using a polyolefin adhesive (hereinafter referred to as "polyolefin insulating tape"). In the course of this research, the above-mentioned poor properties of the polyolefin insulating tape are not caused by the adhesive itself or the polyester film itself as the base material, but by the urethane anchor coat layer used in the insulating tape. I found out what to do and conducted further research. As a result, when the silane-modified polyolefin resin layer is used as the anchor coat layer instead of the urethane anchor coat layer, the heat resistance and water resistance are excellent, and the adhesiveness between the polyolefin adhesive layer and the polyester film is also the anchor. The present invention has been found to be high as in the case where a coat layer is provided. As a result, it is possible to provide an insulating tape having the same excellent properties as an insulating tape using a thermosetting adhesive and having a significantly lower cost.

Next, the present invention will be described in detail.

The insulating tape of the present invention is obtained by using a polyester film, a polyolefin-based adhesive, and a silane-modified polyolefin resin serving as an anchor coat layer.

The polyester film as a base material of the insulating tape is not particularly limited, and a conventionally known one is used. And the thickness is usually 0.012 from the viewpoint of durability, flexibility and electric insulation.
It is set in the range of 0.2 mm. More preferably, 0.
It is in the range of 025 to 0.1 mm.

The polyolefin-based adhesive forming the adhesive layer is not particularly limited, and examples thereof include high density polyethylene (HDPE) and low density polyethylene (LDP).
E), linear low-density polyethylene (L-LDPE), ultra-low-density polyethylene, polypropylene (PP) and their copolymers, and other unsaturated carboxylic acids (acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid) , Crotonic acid, citraconic acid, etc.) or a graft modified product with an acid anhydride (maleic anhydride, itaconic acid anhydride, citraconic acid anhydride, etc.) and the like can be used. Further, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMAA), ethylene-vinyl acetate glycidyl methacrylic acid copolymer (E-VA). -GMA) and the like, those obtained by graft-modifying these resins with alkoxysilane, and ionomers (ethylene-metal acrylate copolymer, ethylene-methacrylate metal ion copolymer) and the like can also be used. it can. When forming an adhesive layer using these polyolefin-based adhesives, it is preferable to set the bending elastic modulus of the adhesive layer in the range of 500 to 20000 kg / cm ² from the viewpoint of buckling resistance. And particularly preferably 1500 to 1500
The range is 0 kg / cm ² , and the optimum range is 2500-1.
It is in the range of 0000 kg / cm ² . Moreover, among such polyolefin adhesives, the melting point is 110 to 1
L, which is in the range of 30 ° C. and has a bending elastic modulus of 2500 to 6000 kg / cm ² when used as an adhesive layer.
An adhesive obtained by graft-modifying LDPE with maleic acid is preferably used. The thickness of the adhesive layer is 0.030 to 0.2 from the relationship of the flexural modulus.
It is preferably set in the range of 00 mm, and particularly preferably in the range of 0.050 to 0.100 mm.

In the present invention, the flexural modulus is J
It is measured by the following method with reference to the bending test method for hard plastics of IS-K7203. That is, a polyolefin-based adhesive layer is formed into a test sample by hot pressing into a size of 10 mm width × 1 mm thickness × 80 mm length. Then, as shown in FIG. 3, the test sample 7 is placed on the two supports 9, and the pressure wedge 8 is moved at a constant speed (5 m).
m / min), the load-deflection curve at this time is recorded on a chart paper, and the bending elastic modulus is calculated by the following formula. In FIG. 3, 10 indicates the distance L between the fulcrums of the two supports 9.

E = L ³ / (4 × bh ³ ) × F / Y [In the above formula, E is the flexural modulus (kg / cm ² ),
L is the distance between fulcrums (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 in the first linear portion of the load-deflection curve.
gf) and Y represent the amount of deflection (cm) under the load F, respectively. ]

The silane-modified polyolefin resin forming the anchor coat layer is not particularly limited, and conventionally known resins can be used. Examples of the silane-modified polyolefin resin include those obtained by graft-polymerizing EEA with alkoxysilane. This silane-modified polyolefin resin has high affinity with both the polyolefin-based adhesive layer and the polyester film, and is excellent in heat resistance and water resistance.
Therefore, by providing an anchor coat layer using the silane-modified polyolefin resin between the polyester film and the polyolefin-based adhesive layer, sufficient adhesiveness between the two can be obtained, and the insulating tape obtained by this is , Will have excellent heat resistance and water resistance. The thickness of the silane-modified polyolefin resin anchor coat layer is set in the range of 3 to 30 μm, preferably 5 to 20 μm.

When it is necessary to impart flame retardancy to the insulating tape when the insulating tape of the present invention is used as a constituent material for a flat electric wire or the like, a flame retardant is blended in the polyolefin adhesive layer to make it The purpose can be achieved. As the flame retardant, decabromodiphenyl ether, hexabromobenzene, tetrabromobisphenol A and its derivatives, bromine flame retardants such as pentabromobenzyl polyacrylate, chlorine flame retardants such as perchlorocyclopentadecane, aluminum hydroxide, water. Examples include inorganic flame retardants such as magnesium oxide, phosphorus-containing flame retardants such as phosphoric acid esters, halogen-containing phosphoric acid esters, and the like. If necessary, a flame retardant aid such as antimony trioxide or zinc borate can also be used together. The blending ratio of these flame retardants is such that the polyolefin adhesive 10
It is preferably set in the range of 20 to 250 parts with respect to 0 parts by weight (hereinafter abbreviated as “part”).

In addition to the above flame retardant and flame retardant auxiliary,
Various additives conventionally used in polyolefin adhesive layers can be blended as necessary. Examples of these additives include inorganic fillers such as titanium dioxide, talc, and alumina, and antioxidants, copper damage inhibitors,
Examples include UV absorbers.

The insulating tape of the present invention can be manufactured by using the above raw materials, for example, as follows.
That is, when a pellet-shaped polyolefin adhesive is prepared and a flame retardant or the like needs to be blended, the pellets are blended with a predetermined amount of the flame retardant or the like and kneaded using a biaxial mixer or the like, Water-cool, cut and pelletize again. On the other hand, pellet-shaped silane-modified polyolefin resin is prepared, and this is extrusion-laminated on a polyester film by a T-die extruder or the like. Then, the above-mentioned pelletized polyolefin adhesive is extrusion-laminated with a T-die extruder or the like on the polyester film laminated with the silane-modified polyolefin resin. In this way, an insulating tape having a three-layer structure as shown in FIG. 1 can be obtained. In FIG. 1, 1 is a polyolefin adhesive layer, 2 is a silane-modified polyolefin resin anchor coat layer, and 3 is a polyester film. Note that the above steps can also be performed by a series of steps in which a polyolefin-based adhesive and a silane-modified polyolefin resin are simultaneously extrusion-molded, and immediately after that, these films and a polyester film are laminated.

[0017]

As described above, according to the present invention, an anchor coat layer made of a silane-modified polyolefin resin is provided on an insulating tape having a polyester film and a polyolefin adhesive layer. That is, since an anchor coat layer made of a silane-modified polyolefin resin is provided in place of the conventional urethane-based anchor coat layer, the polyester film and the polyolefin-based adhesive layer maintain high mutual adhesiveness, and The poor heat resistance and poor water resistance due to the anchor anchor coat layer are eliminated, and it has sufficient properties for practical use. In particular,
Since the insulating tape of the present invention uses an inexpensive polyolefin adhesive and a silane-modified polyolefin resin, the cost is significantly lower even though the performance is equivalent to that using the conventional thermosetting system. Become. Moreover, by setting the flexural modulus of the polyolefin-based adhesive layer in a predetermined range, for example, in the range of 500 to 20,000 kg / cm ² , excellent buckling resistance can be provided.

Next, examples will be described together with comparative examples.

Prior to the examples, Tables 1 and 2 below.
Additives such as the four types of polyolefin-based adhesives and flame retardants shown in 1 were prepared. In Table 1, MI is melt index (g / min), cont. Represents the vinyl acetate content (% by weight), and mp represents the melting point.

[0020]

[Table 1]

[0021]

[Table 2]

Examples 1 to 5 Insulating tapes were produced according to the method described above. The polyolefin-based adhesive layer was formed with five types of flexural moduli according to the compounding ratios shown in Table 3 below. Silane-modified EEA was used as the silane-modified polyolefin resin as the material for forming the anchor coat layer.

[0022]

[Table 3]

[0023]

[Comparative Examples 1 and 2] Insulating tapes were produced according to the method described above except that a urethane-based anchor coat layer was provided instead of the silane-modified polyolefin resin anchor coat layer. In addition, the polyolefin-based adhesive layer was formed with two types of flexural modulus according to the blending ratio shown in Table 4 below.

[0024]

[Table 4]

The products of Examples 1 to 1 thus obtained
5, the heat resistance, the water resistance, the buckling resistance, and the adhesiveness of the adhesive layer of the comparative examples 1 and 2 were examined. The results are shown in Table 5 below. The above characteristics were examined according to the following methods.

[Heat Resistance] The adhesive layer of the insulating tape was adhered to a rolled copper foil (thickness 50 μm, untreated product) by the heat roll laminating method. At this time, the laminating conditions are as follows: a roll temperature of 175.degree.
m / min, laminating linear pressure was 6.0 kgf / cm.
Then, the obtained adhesive was cut into a width of 10 mm to obtain a test sample. This was put in a gear oven at 135 ° C. for 168 hours to be heat treated, and then a sample was taken out, by a strograph (R-2 type manufactured by Toyo Seiki Co., Ltd.)
A 180-degree peel test was performed at a speed of 50 mm / min, and the peel strength at that time was measured.

[Water resistance] A test sample obtained in the same manner as described above was placed in hot water at 80 ° C., taken out 168 hours later, and subjected to a 180 ° peel test at a speed of 50 mm / min by the above-mentioned strograph. The peel strength at that time was measured.

[Adhesiveness of Adhesive Layer] A test sample obtained in the same manner as above was subjected to 50 minutes per minute by the above-mentioned strograph.
A 180-degree peel test at a speed of mm was performed, and the peel strength at that time was measured.

[Buckling resistance] Two insulating tapes were adhered by a heat roll laminating method under the same conditions as in the above evaluation of heat resistance so that the adhesive layers contact each other, and further 50 mm width × A test sample was molded into a length of 150 mm. Using this test sample, buckling resistance was evaluated using the strograph.
That is, as shown in FIG. 4, the test sample 12 is placed between the two support plates 14a and 14b, and the tape 13
Fix with. Then, a compressive force is applied by moving the support plate 14b in the direction of the arrow at a constant speed, and the sample 1
2 is pressed until it is completely bent, and the load-compression distance curve at that time is recorded on chart paper. In addition, in FIG. 4, 11 shows a load cell. An example of a curve diagram of this load-compression distance is shown in FIG. In FIG. 5, the curve 16 is a curve when there is no buckling,
Curve 15 is a curve when buckling. In curve 15, when buckling, peak 17 appears. Therefore,
In the evaluation of buckling resistance, those in which this peak did not appear were represented by ◯, and those in which this peak appeared were represented by x.

[0030]

[Table 5]

From the results in Table 5 above, it can be seen that the insulating tapes of all the examples have high performances in terms of adhesiveness, heat resistance, water resistance and buckling resistance. On the other hand, the insulating tapes of Comparative Examples 1 and 2 were inferior in heat resistance and water resistance. Further, the insulating tape of Comparative Example product 2 was also inferior in buckling resistance.

[Brief description of 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. 3 is an explanatory diagram of a method for measuring flexural modulus.

FIG. 4 is an explanatory diagram of a method for evaluating buckling resistance.

FIG. 5 is a load-compression distance curve diagram obtained by the above buckling resistance evaluation method.

[Explanation of symbols]

 1 Polyolefin adhesive layer 2 Silane-modified polyolefin resin anchor coat layer 3 Polyester film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuzo Asano 3600 Gyokutsuyama, Komaki City, Aichi Prefecture Totsugu Rubber Industry Co., Ltd.

Claims (1)

[Claims] 1. An insulating tape having a polyolefin adhesive layer laminated on a film surface of a polyester film, characterized in that a silane-modified polyolefin resin anchor coat layer is formed between the two. Insulating tape.