JPS6217803B2 - - Google Patents

Description

[Detailed description of the invention]

[Objective of the Invention] (Industrial Application Field) The present invention relates to a mica tape for electrical insulation, in which a tape base material in which mica is supported on a reinforcing material is impregnated with a diallyl phthalate resin composition in a tack-free semi-cured state. Regarding prepreg type mica tape. (Prior art) Conventionally, in electrical equipment such as rotating machines and transformers, mica tape has been used by wrapping it around a conductor to insulate large-capacity equipment coils. It is adjusted by impregnating it. There are two types of mica tape,
One type is called F type, which has an operating temperature of 155°C and is usually impregnated with epoxy resin, and the other is called H type, which is heat resistant and can be used at 180°C and is usually impregnated with silicone resin. It is used after being impregnated. This mica tape is prepared by a vacuum impregnation method or a prepreg method. In the former, mica coated with a conductor is impregnated with resin under vacuum and then cured by heating, which suppresses external oozing of the resin during curing. The prepreg method has been adopted because of the disadvantages of temperature control, long production times, and short pot life of the resin when producing in small quantities. In this prepreg method, the conductor is wound around a mica tape in which the required amount of resin is applied to the mica layer in advance, and then the conductor is cured under heat and pressure. According to this method, the drawbacks of the vacuum impregnation method mentioned above are improved to some extent. Ru. (Problem to be solved by the invention) However, even in the above method, F
Heat-resistant resins such as epoxy resin used for seed mica tape, silicone resin, polyimide resin, and polyester imide resin used for high-temperature H type are prepared by winding a prepreg-like tape of these resins around a conductor. After making it into a coil, the desired characteristics cannot be achieved unless it is heat-treated at high temperature for a long period of time.
The production time is still long, requiring heating at 180℃ to 200℃ for more than ten hours each. Furthermore, in devices that cannot be exposed to such high temperatures, the coil must be made separately and then assembled, making it impossible to heat-treat the coil in advance by assembling it into the device, increasing the number of man-hours needed to assemble the device. There is. Therefore, in order to accelerate this curing, a curing agent can be used in conjunction with the tape, but tapes prepared in prepreg form using resin containing a curing agent have a short pot life, so it is necessary to hardens,
When it hardens, it becomes too hard and cannot be rolled. Furthermore, epoxy resins, silicone resins, polyimide resins, etc., especially the latter, are hard even in an uncured state, making it difficult to wind the tape. In order to compensate for this drawback, it is possible to mix a reactive component that imparts flexibility, but such a reactive component significantly deteriorates the electrical insulation properties at high temperatures, and the degree of deterioration is particularly limited for H-type products. A major problem was that the electrical insulation properties of mica were diminished. [Structure of the Invention] (Means for Solving the Problems) The present invention has been made in view of the above problems, and includes forming a tape base material by supporting mica on a reinforcing material, and impregnated with a resin composition containing a diallyl phthalate prepolymer and a modifier and a curing agent made of an organic compound having at least one addition-polymerizable double bond, and further heated to semi-cure to a tack-free semi-cured state. , we provide a mica tape that can be maintained stably at room temperature in this state, provide flexibility that makes it easy to wind the tape around a conductor, and extend its usable life. When used, the semi-cured resin composition is made to be curable at relatively low temperatures. The present invention also provides a mica tape for electrical insulation that contributes to shortening the manufacturing period and the number of man-hours for assembling equipment, and can stabilize electrical insulation properties at a high level due to the heat-resistant structure and water-resistant structure of the resin composition. In the tape base material used in the present invention, mica is supported on a reinforcing material such as glass cloth, aromatic polyamide nonwoven fabric, or polyimide film, and the mechanical strength of the mica is reinforced by this reinforcing material. Mica is
Although peeled mica may be used, it is advantageous to use aggregated mica because it has excellent quality stability, dimensional uniformity, and economical efficiency. Further, the diallyl phthalate resin composition (hereinafter referred to as resin composition) used in the present invention comprises a diallyl phthalate prepolymer, a regulator having an addition-polymerizable double bond, and a curing agent. Diallyl phthalate prepolymer (hereinafter referred to as prepolymer) is diallyl orthophthalate,
A curing agent such as benzoyl peroxide is added to a diallyl phthalate such as diallyl isophthalate and polymerized by heating, and the reaction is stopped by stopping the heating before the polymer reaches the gelation point to separate the diallyl phthalate monomer and a gel-like substance. After removal, only the appropriate molecular weight was collected and kept stable at room temperature. This prepolymer has a softening point of about 80° C. or less and is a thermoplastic resin. The modifier consists of a liquid organic compound having one or more double bonds such as a vinyl group, and a typical example thereof is diallyl orthophthalate monomer, but it also includes diallyl isophthalate monomer or triaryl isophthalate monomer. Allyl isocyanate, diallyl chlorenate, etc. may also be used. Suitable curing agents include benzoyl peroxide, tert-butyl peroxybenzoate, dicumyl peroxide, and acetyl benzoyl peroxide, but are not limited to these, and any curing agent that functions as a polymerization initiator may be used. It is preferable that the polymerization initiation ability is not large and that the resin composition can be cured within several hours, for example, 1 to 3 hours, from 100°C to 150°C. However, it is not limited to this.
Generally, benzoyl peroxide and tert-butyl peroxybenzoate are easy to use not only in terms of performance but also in terms of price. In this case, benzoyl peroxide is
It has a polymerization initiation effect at a lower temperature than butyl peroxybenzoate, and is suitable for mica tapes used in areas that are difficult to maintain at high temperatures, such as coil ends. The blending ratio of the prepolymer, regulator, and curing agent is as follows: 100 parts by weight of the prepolymer, 5 to 200 parts, preferably 10 to 40 parts, of the regulator, and 0.5 to 5% by weight of the curing agent added to the mixture. All you have to do is mix the agent. If the modifier is less than 10 parts per 100 parts of the prepolymer, the resin composition will not have flexibility, and the mica tape impregnated with this resin composition will not be able to be wound around a conductor smoothly. . In such cases, 1 to 5% by weight of a solvent may be added to soften the material. In addition, when the amount of the modifier is increased, the viscosity of the resin composition decreases, making it possible to impregnate mica without adding a solvent, making it possible to create a mica tape with high flexibility. The shrinkage rate at the time of curing is large, and the heat resistance of the cured resin composition is also reduced. If the amount of regulator used exceeds 200 parts per 100 parts of prepolymer, the viscosity of the resin composition will be too low, reducing the bonding strength of mica and reinforcing material, and making it difficult to bond them together sufficiently. It becomes difficult to control the thermal polymerization so as to impart appropriate flexibility. Further, the resin composition is impregnated into the tape base material and semi-cured by heating to bring it into a tack-free, ie, contact dry state. In order to impregnate a resin composition, permeability will be improved if it is dissolved in a solvent and the viscosity is lowered to increase fluidity.
In addition, when the amount of resin impregnated is, for example, 40 to 60% by weight, there is no problem at all with the windability of the impregnated tape and the electrical insulation properties after curing. If held at 100℃ for 30 minutes, it will be in a tack-free semi-cured state, and if raised to a higher temperature, it will be completely cured. In this way, the amount of resin is selected based on the balance between windability and insulation, and the heating time and heating temperature are also selected appropriately. It is best to heat it at a relatively low temperature for a long time. In addition, although the above explanation was about the F-type mica tape, the H-type mica tape includes a diallyl isophthalate prepolymer as a diallyl phthalate prepolymer, a diallyl isophthalate monomer as a regulator, or a triallyl Using isocyanate, the blending ratio of the resin composition is
5 to 100 parts of monomer per 100 parts of prepolymer
%, and the upper limit is set smaller than in the case of the previous F type.
Other conditions are the same as in the case of F type. This H
The type of resin composition has particularly improved heat resistance, can sufficiently withstand the use conditions of type H at 180°C, and has a particularly small loss on heating. (Function) In the present invention, when the tape base material is impregnated with the diallyl phthalate resin composition, the surface is sticky at room temperature and can be maintained in an uncured state for a long time, but when heated, the curing agent loses its polymerization initiation ability. have,
It is added to the double bonds of the diallyl prepolymer and the regulator to radicalize them, and these radicals are then sequentially added to the double bonds of other prepolymers or the regulator to proceed with polymerization and form a three-dimensional network. Then, when heating is stopped, polymerization almost stops. If the stopping timing is selected so that the resin composition loses its tackiness, that is, it becomes tack-free and dry to the touch, the reaction can be stopped in a semi-cured state, and if this semi-cured state is maintained at room temperature. This semi-cured state can be maintained, and even when the mica tape impregnated with the resin composition is wound in a spiral shape, it does not fuse with each other, making it convenient for storage.
When making a coil, this mica tape can be wound around a conductor to maintain appropriate flexibility. and,
When a mica tape impregnated with this semi-cured resin composition is wound around a conductor and then heated, unreacted double bonds are further polymerized to form a network, making it possible to obtain a heat-resistant structure. At this time, the polymerization initiation temperature of the curing agent is higher than room temperature, so even if the temperature after wrapping the tape around the conductor is maintained at a temperature of 100°C or higher and 150°C or lower, it will harden within a few hours. Moreover, flexibility can be maintained appropriately and heat resistance can also be maintained. As a result, it has thermal stability as an insulator for coils used under high voltage, and therefore does not deteriorate its insulation properties due to softening, decomposition, etc. Further, the diallyl phthalate resin composition has a relatively hydrophobic structure and has excellent water resistance and moisture resistance compared to epoxy resins and unsaturated polyester resins. (Example) Next, an example of the present invention will be shown, and furthermore, the results of measuring the flexibility, dielectric loss tangent tan δ, Δtan δ, breakdown voltage, and water absorption of mica tape will be shown by comparing this example with a comparative example. Here, Examples 1 and 2 are F type, and Examples 3 and 4 are H type. Example 1 70 parts of diallyl orthophthalate prepolymer (Osaka Soda Co., Ltd. trade name: Datpu-L) (hereinafter parts by weight are shown), 30 parts of diallyl orthophthalate monomer (Osaka Soda Co., Ltd. trade name: Datup Monomer), and tertiary butyl peroxy A resin composition consisting of 1 part of benzoate is dissolved in 100 parts of methyl ethyl ketone to prepare a varnish with a resin content of 50%.
Next, a tape base material in which laminated mica as mica with a thickness of 0.06 mm was layered on one side of glass cloth as a reinforcing material with a thickness of 0.03 mm was impregnated with the varnish, and then heat treated at 100 ° C. for 30 minutes. , while evaporating the solvent, semi-curing the adhered resin composition to make it dry to the touch and tack-free, with a thickness of approximately 0.13 mm.
mm, making mica tape with a resin content of about 40%. Example 2 A resin composition consisting of 80 parts of diallyl orthophthalate prepolymer (same type as in Example 1), 20 parts of diallyl orthophthalate monomer (same type as in Example 1), and 1 part of benzoyl peroxide was added to 100 parts of methyl ethyl ketone. Dissolve to prepare a 50% resin varnish. Next, a tape base material of 0.08 mm thick laminated mica with 0.03 mm thick glass cloth placed on both sides as a reinforcing material was impregnated with the varnish, and then treated at 70°C for 40 minutes to volatilize the solvent. Then, the resin is semi-cured to produce a surface tack-free mica tape in the same manner as in Example 1. The thickness of the tape thus obtained is approximately 0.24 mm and the resin content is approximately 55%. Example 3 Consisting of 80 parts of diallyl isophthalate prepolymer (Osaka Soda Co., Ltd. trade name: Datsupu-100L), 20 parts of diallyl isophthalate monomer (Osaka Soda Co., Ltd. trade name: Datsupu 100 monomer), and 1 part of tertiary butyl peroxybenzoate. Dissolve the resin composition in 100 parts of methyl ethyl ketone,
Prepare a varnish with a resin content of 50%. Then the thickness is 0.03
On one side of glass cloth as reinforcement of mm, thickness
A tape base layered with 0.06 mm laminated mica was impregnated with the varnish, and then heated at 100°C for 30 minutes.
While the solvent is evaporated, the adhered resin is semi-cured to make the surface tack-free as in Example 1, and a mica tape with a thickness of about 0.13 mm and a resin content of about 40% is produced. Example 4 A resin composition consisting of 80 parts of diallyl isophthalate prepolymer (Osaka Soda Co., Ltd. trade name: Datsupu 100L), 20 parts of triallyl isocyanurate (Nippon Kasei Co., Ltd. trade name: Taiku), and 1 part of tertiary-butyl peroxybenzoate. is dissolved in 100 parts of methyl ethyl ketone to prepare a varnish with a resin content of 50%. Next, a mica tape having a thickness of about 0.13 mm and a resin content of about 40% is made by the same method as in Example 3. Comparative Example 1 According to Example 1, epoxy resin (epoxy resin)
Mica tape impregnated with acid anhydride-tertiary amine type. Comparative Example 2 Mica tape impregnated with unsaturated polyester resin instead of the epoxy resin of Comparative Example 1. Comparative Example 3 Mica tape impregnated with silicone resin instead of the epoxy resin of Comparative Example 1. Comparative Example 4 Mica tape impregnated with polyimide resin instead of the epoxy resin of Comparative Example 1. The mica tape thus obtained is subjected to the following tests. (a) Flexibility test Place the above mica tape test piece under the following conditions and measure according to JISC2116. In Examples 1 and 2 and Comparative Examples 1 and 2, 5°C
Or leave it indoors at 25℃ for 6 months. In Examples 3 and 4 and Comparative Examples 3 and 4, 15°C
Leave it in the following room for 3 months. (b) Dissipation tangent tanδ, Δtanδ, breakdown voltage test Half a mica tape is applied to the copper wire as a conductor 3
After winding, for Examples 1 and 2, 100
℃ 3 hours, for Examples 3 and 4, 150℃ 2
time, Comparative Example 1: 150°C for 15 hours, Comparative Example 3:
Then, heat-cure at 200℃ for 20 hours to prepare a test piece, and calculate the temperature characteristics of dielectric loss tangent tanδ, Δtanδ
(Difference between tanδ of 3.3KV/mm and tanδ of 1KV/mm)
and dielectric breakdown voltage was measured. This measurement is performed at a frequency of 50 Hz using the Schering Bridge method. (c) Water absorption test Cut a 20 x 20 mm test piece from the insulating layer formed on the conductor using the same method as in the previous section (b). After this test piece is immersed in boiling water for 8 hours, the weight change rate is determined. The results of this test are shown in the following table for Δtanδ and breakdown voltage, and the flexibility measurements and temperature characteristics of tanδ are shown in the attached drawings.

〔Effect of the invention〕

According to the present invention, when impregnating a resin composition into a tape base material in which mica is supported on a reinforcing material, the resin composition is mixed with a diallyl phthalate prepolymer,
It is composed of a modifier and a curing agent made of an organic compound having at least one addition-polymerizable double bond, and a tape base material is impregnated with this resin composition and semi-cured by heating to produce a tack-free semi-cured state. The resin composition is composed of a prepolymer that has heat resistance and a modifier that adjusts flexibility, and a curing agent whose polymerization initiation ability is small at room temperature and can be increased by heating.The resin composition supports mica as a reinforcing material. After impregnating the tape base material, it is heated to semi-cure it to a tack-free state, and in this semi-cured state, it is returned to room temperature to stop the reaction, and it can be stored as it is for a long period of time at room temperature, and the tapes do not fuse to each other. In addition to being able to overlap and wrap the tape around the conductor, its flexibility allows the work to be carried out smoothly, and by heating the tape again after winding, the curing of the resin composition can be further promoted. For example, the heating temperature is
Sufficient curing can be achieved by heating for several hours at a relatively low temperature of 100°C to 150°C, and a high level of electrical insulation can be maintained without impairing the properties of mica. As a result, the curing period for conventional prepreg-type insulating tapes is significantly shortened, and the heat-curing temperature is low, making it possible to heat-cure the tape after it has been incorporated into equipment. In particular, the H type insulating tape, which has conventionally been difficult to produce, can be easily obtained by using a diallyl isophthalate prepolymer resin composition, and its practicality can be significantly increased. Furthermore, the diallyl phthalate resin composition has better moisture resistance and water resistance than conventional epoxy resins and polyester resins, and can maintain high performance electrical insulation.

[Brief explanation of the drawing]

FIG. 1 is a graph showing changes in flexibility over time of the first example of the mica tape of the present invention and comparative examples 1 and 2;
Fig. 2 is a graph showing the temperature characteristics of tan δ of the first and second examples, Fig. 3 is a graph showing changes in flexibility over time of the third example and comparative examples 3 and 4, and Fig.
The figure is a graph showing the temperature characteristics of tan δ in the third and fourth examples.

Claims (1)

[Scope of Claims] 1. A tape in which a resin composition comprising a diallyl phthalate prepolymer and a modifier and a curing agent made of an organic compound having at least one addition-polymerizable double bond is supported on a reinforcing material of mica. A mica tape for electrical insulation, characterized in that it is formed into a tack-free semi-cured state by impregnating it into a base material and semi-curing it by heating. 2. The mica tape for electrical insulation according to claim 1, characterized in that the diallyl phthalate prepolymer is a diallyl orthophthalate prepolymer. 3. The mica tape for electrical insulation according to claim 1, characterized in that the diallyl phthalate prepolymer is a diallyl isophthalate prepolymer.