JPS6148204B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an insulating tape.

Conventionally, a wide variety of insulating tapes have been developed and put into practical use for insulating electrical equipment. However,
Recently, such insulating tapes have not only excellent electrical and mechanical properties, but also good heat resistance and moisture resistance, excellent initial adhesion and adhesive strength, and excellent insulation workability during winding. A number of properties have been required, including superior properties and non-corrosion to adherends such as copper adherends.

This invention was discovered as a result of intensive studies to develop a new insulating tape that satisfies the above-mentioned required characteristics. The present invention relates to an insulating tape coated with a pressure adhesive composition and wound through an embossed polyethylene film.

That is, since the insulating tape of the present invention is mainly composed of a heat-resistant base material and a thermosetting silicone resin as a pressure-sensitive adhesive component, the insulating tape has good heat resistance and moisture resistance, and also has good heat resistance and moisture resistance. In addition to having the advantages of not being corrosive to adherends and having excellent thermal conductivity, this type of tape functions as so-called adhesive tape, self-fusing tape, and prepreg tape, so it can be In addition to good adhesive strength, it also has excellent electrical and mechanical properties upon heat curing.

By the way, when such a tape is mainly made of a heat-resistant base material and a thermosetting silicone resin and is stored by winding it with a regular release paper, the adhesive layer will change over time to the release paper surface. Adhesive transfer is likely to occur, resulting in problems with insulation work, and partial loss of the adhesive layer may result in poor insulation, which may adversely affect various properties such as electrical properties, heat resistance, and moisture resistance. There is a problem that it lacks practicality as an insulating tape.

However, in this invention, since a particularly embossed polyethylene film is used as the release paper, such a release film effectively prevents the adhesive layer from becoming sticky over time and prevents the adhesive layer from being exposed during use. Not only is the insulation workability greatly improved when wrapping around the adherend, but the adhesive layer is not partially missing, resulting in improved electrical properties, heat resistance,
The moisture resistance and other properties described above can be fully satisfied.

The heat-resistant base material used in this invention includes woven fabrics and non-woven fabrics made of inorganic fibers such as glass fibers and carbon fibers, and aromatic polyamide paper, and the thickness thereof varies depending on the purpose of use.
Generally, it is about 0.03 to 0.20 mm.

The pressure-sensitive adhesive composition applied to both sides of the base material has a thermosetting silicone resin as an adhesive component, and this adhesive component contains a curing agent such as an organic peroxide such as benzoyl peroxide or a platinum catalyst. Agents, fillers and other known additives may be blended. A particularly effective filler is titanium white, and when titanium white is added, the releasability between the adhesive layer and release paper is further improved, resulting in good insulation workability. The amount of titanium white added is preferably 10 to 30 parts by weight per 100 parts by weight of the thermosetting silicone resin; if too much is added, problems such as a decrease in adhesive strength will occur. Although it is possible to use fillers other than titanium white, they generally have poor compatibility with thermosetting silicone resins, settle over time, and are difficult to disperse uniformly, resulting in variations in properties such as adhesive strength. Easy to occur.

As the thermosetting silicone resin used alone as an adhesive component, a wide variety of conventionally known thermosetting silicone resins can be used.
A silicone resin mixture consisting of component d can be mentioned.

a The average number of methyl groups and phenyl groups per silicon atom is 1.4 to 1.8, the ratio of phenyl groups to silicon atoms is 0.5:1 to 0.8:1, and contains a hydroxyl group bonded to the silicon atom. Methylphenylpolysiloxane resin.

b Contains 0.15 to 0.60 vinyl groups per silicon atom, the average number of silicon atoms per molecule is 8 or more, and the ratio of phenyl groups to silicon atoms is
0.35:1.75 to 1.75:1, and the average number of hydrocarbon groups per silicon atom added to silicon atoms through silicon-carbon bonds is 1.
The above polysiloxane, wherein the hydrocarbon group is selected from a methyl group, a phenyl group, and a vinyl group.

c The average number of SiH groups per molecule is 2 or more, the remaining valences of silicon atoms are essentially all filled by aromatic hydrocarbon groups, methyl groups, and SiOSi bonded chains, and the above b component is A siloxane that is compatible with components a and b and is present in an amount necessary for gelation.

d A catalyst for promoting the reaction between component b and component c described above.

Such a silicone resin mixture is gelled by the reaction between component b and component c, but this gelled product still exhibits pressure-sensitive adhesive properties and can be further heated to a high temperature to advance the curing reaction of component a. As a result, it exhibits strong adhesive strength, excellent heat resistance, moisture resistance, and other properties. There is a commercial product available under the trade name SH-4280 manufactured by Toray Silicone Co., Ltd., which has a solid content of 60~60 ~
63% by weight (measurement conditions 1 hour/150℃) xylene solution (opaque appearance, viscosity 90,000~ at 25℃)
140,000 centipoise).

The means for applying the pressure-sensitive adhesive composition to the heat-resistant base material is arbitrary, and known methods such as dipping and brushing can be employed. The amount applied is generally the total amount with the base material.
It may be about 50 to 90% by weight. After this application, a pressure-sensitive adhesive layer is formed by heating and drying. However, in the case of using a thermosetting silicone resin consisting of the above-mentioned components a to d, heat treatment is performed during or after the above-mentioned heating and drying. This promotes the reaction between component b and component c.

In this invention, after the adhesive layer is formed as described above, it is wound through an embossed polyethylene film to form an insulating tape.
Only in this way can an insulating tape with good releasability be obtained. Embossed polyethylene film is a polyethylene film in which an embossed pattern (irregularities) is formed on both the front and back sides of the film by a known method that can be detected visually or even by touch, and many are already commercially available. The thickness of this film should just be the usual thickness (0.05 to 0.20 mm) for a release paper. The thus obtained insulating tape of the present invention exhibits the above-mentioned excellent properties by peeling off the release paper, wrapping it around various devices, and heating and curing it during use.

Next, examples of this invention will be described.

Example SH-4280 (thermosetting silicone resin mentioned above)
, titanium white, and benzoyl peroxide as a hardening agent were dissolved in toluene at a solid content weight ratio of 100:20:1.1 to obtain a solid content of 30% by weight.
A pressure sensitive adhesive solution was prepared.

This solution was applied and impregnated onto a 0.1 mm thick glass cloth (trade name: EPC-100W manufactured by Arisawa Seisakusho), and
By heating and drying at ℃ for 30 minutes, the total thickness is 0.16 mm.
A pressure-sensitive double-sided adhesive sheet is then cut into a predetermined width, and an embossed polyethylene film having the following properties (embossed on both sides of an extrusion high-speed polyethylene film made by Dainik Co., Ltd.) An insulating tape of the present invention was prepared by winding the tape through the tape.

<Characteristics of embossed film> Thickness: 0.08mm Peel strength: 249g/20mm width Yield point (longitudinal): 1.63Kg/10mm 100% modulus: 1.25Kg/10mm Tensile strength: 1.32Kg/10mm Elongation: 424% This insulating tape After leaving the film at 30°C and 100% RH for 180 days, the embossed polyethylene film had excellent peeling properties and could be wrapped around various electrical devices. In addition, by heating and curing at 180°C for 60 minutes after wrapping, a cured insulating layer with excellent electrical and mechanical properties, heat resistance, moisture resistance, and non-corrosion properties was formed. In addition, below,
Typical properties before and after curing are shown.

Adhesive strength (before curing): 323 g/15 mm width (vs. stainless steel plate) Elongation: 3.2% Tensile load: 31.3 Kg/15 mm width Thermal conductivity: 7 to 8 x 10 ^-4 ca/cm゜sec・℃ Breakdown voltage ; 6.0KV Volume resistivity; 2.93×10 ¹⁵ Ω-cm Heat resistance; No change for 10,000 hours at 250℃.

Claims (1)

[Claims] 1. An insulating tape obtained by applying a pressure-sensitive adhesive composition containing only a thermosetting silicone resin as an adhesive component to both sides of a heat-resistant base material and winding the tape with an embossed polyethylene film interposed therebetween. . 2. The insulating tape according to claim 1, wherein the pressure-sensitive adhesive composition contains 10 to 30 parts by weight of titanium white per 100 parts by weight of thermosetting silicone resin.