JPS5974168A - Film formation - Google Patents

Abstract

PURPOSE:To form films without run-off of impregnated resins, by a process wherein an aq. polymer liq. is applied to yield films, which are immersed in a vapor or liq. of carboxylic acid to cure the polymer for preventive measures against run-off of impregnated resins used for insulation. CONSTITUTION:As means for forming films and sealing for preventive measures against run-off of flowable liqs. (impregnated resins) used for insulation of electric equipment or electronic components, an aq. polymer liq. (e.g., a water-base liq. comprising natural or synthetic rubber particles dispersed in water) are applied. Latexes such as acrylate latex are used as said aq. liq. Then, to change the hydrogen ion concn. of the coating film, the film is immersed in vapor or liq. of carboxylic acids to form a coating film by curing of the polymer, such as rubber coagulation or quickly oxidizable film formation. The drawing shows the state at which a latex 6 held to a stator 1 is being cured in acetic acid vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a means for preventing a liquid resin impregnated for the purpose of insulating electrical equipment from changing over time and leaking out to the outside. After applying an aqueous liquid in which particles are dispersed in water (hereinafter referred to as latex), the coated film is immersed in carboxylic acid vapor or carboxylic acid liquid to prevent rubber agglomeration or formation of a fast-oxidizing film (hereinafter referred to as both). The idea was to make the entire surface layer of the liquid resin undergo hardening.

Generally, electric motors, molded transformers, generators, etc. are impregnated or coated with liquid resin and then cured for the purpose of insulation.

For example, insulation treatment for electric motors will be explained in detail.

Insulating material such as mica or glass tape is wrapped several times on the surface of a coil made by bundling multiple enameled wires using taping techniques. Since mechanical strength and insulation properties are insufficient if left as is, low-viscosity thermosetting impregnating resin (hereinafter referred to as impregnating resin) is impregnated into the inside of mica, glass tape, etc. under vacuum and pressurized conditions.

After impregnation, the whole is heated to 100-1 to harden the impregnated resin.
Heat to 50°C. However, during the heating process, the impregnated resin flows out before it hardens.
The inside of the camera or glass tape becomes hollow,
Problems such as decreased mechanical strength and insulation performance arise. In other words, the impregnated resin needs to be impregnated to the inside through a very small space covered with mica or glass tape, so it is required to have a low viscosity, and the viscosity of the impregnated resin for electric motors is 200 ops or less. There are many things.

On the other hand, since a thermosetting resin is generally used as the impregnating resin, it must be heated and hardened after impregnation, and the entire
Heated from 0 to 150°0. Heating increases the temperature of the impregnated resin and reduces its viscosity. When the viscosity decreases, the resin that has once been impregnated inside the mica or glass tape easily flows out, leaving a void inside.

In order to solve the above-mentioned problems, a method has been used in which the entire material is cured while being rotated immediately after impregnation. However, this method requires a device to rotate it in a heating furnace, it is difficult to rotate items from multiple manufacturers at once, some items have structures that cannot be rotated, and the power costs are high to rotate heavy items. It has disadvantages such as.

The present inventors conducted extensive research to improve the drawbacks of the conventional methods described above, and as a result, they arrived at the present invention.

A film forming method characterized by curing the polymer by changing the hydrogen ion concentration of the aqueous polymer liquid or adding cations to the polymer aqueous liquid as a means for forming and sealing the polymer. Regarding. In other words, as a method to prevent the impregnated resin from flowing out after impregnation using a completely different method than conventional methods, the impregnating method takes advantage of the fact that latex hardens when the hydrogen ion concentration (hereinafter referred to as pH) of latex is changed or cations are added to latex. Latex is applied to the surface of the coil after or before impregnation by a dipping method or a spray method, and then the latex on the surface is hardened within just 5 seconds by immersing it in the vapor of a carboxylic acid such as acetic acid or in i. I was inspired by a method to form a film that prevents the impregnated resin from flowing out.

Examples of the polymers used in the present invention include acrylate-based, acrylonitrile-butadiene-based, and styrene-butadiene-based polymers that can generally be used as aqueous liquids.

The aqueous polymeric liquid used in the present invention includes conventional aqueous liquids such as emulsions or latexes of the aforementioned polymers.

Examples of carboxylic acids for changing the pH of the aqueous polymer liquid used in the present invention include formic acid, acetic acid, propionic acid,
Commonly used monobasic carboxylic acids such as butyric acid or caproic acid may be cited, and cations added to the aqueous polymer solution may include cations generated from NaOl, C&C12, AIO13, and the like.

As a method for curing an aqueous polymeric liquid with the carboxylic acid of the present invention, there are methods such as passing the aqueous polymeric liquid through carboxylic acid vapor or immersing it in a carboxylic acid liquid.

When an aqueous polymeric liquid such as latex comes into contact with carboxylic acid, the pH of the latex changes to the acidic side.
The surface hardens at a high speed of less than 5 seconds, which cannot be achieved with normal chemical reactions, forming a film. After the film is formed, the impregnated resin is cured in a heating furnace. Although the viscosity of the impregnated resin impregnated into the coil decreases due to heating, since there is a latex film on the surface, it can be cured without flowing out. If the latex film becomes a hindrance to the product after curing, it can be easily removed since latex has no adhesive properties.

In addition to changing the pH of the latex to the acidic side, the following method can also be used to rapidly cure the latex. In other words, because latex uses an anionic emulsifier, it is relatively stable against anions, but on the other hand, when cations are mixed in, counterions (cations) are adsorbed to the interface of latex particles. It is known that the electric double layer is compressed by the adsorption of counterions, the potential disturbance between latex particles is reduced, and the latex is hardened. For example, Nap/% OaO/
2. When the latex is brought into contact with an aqueous solution such as Al (1'/3), a fast-curing film is formed, and it can be cured at a high speed similarly to when the pH is changed.

In the present invention, a conventional method such as a dipping method or a spray method is used to apply an aqueous polymeric liquid such as latex to the surface of an electric motor or the like impregnated with an impregnating resin.

EXAMPLES Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 Small electric motor stator (hereinafter referred to as stator) (1)
80% The coil (3) was impregnated with the impregnating resin (4) by immersing it in the impregnating resin (4) for 120 minutes at 1 mmH.

After impregnation, take it out and put it in latex (6) (Nipole 4850, Nippon Zeon ■) at 25°C for about 1 hour as shown in Figure 6.
After being immersed for 0 seconds, it was taken out and immediately placed in acetic acid (7) vapor (10) at 25°C as shown in FIG. When the latex (6) comes into contact with the vapor of acetic acid (7), the pH of the latex (6) changes to the acetic acid side.
It cured within 5 seconds, a high speed that cannot be achieved with normal chemical reactions, and formed a film. After the film was formed, the impregnated resin (4) was thermally cured at 100°C for 60 minutes in a heating furnace. It was possible to heat cure without curling during heat curing.

Table 1 shows the amount of the impregnated resin (4) adhered to the stator (1) after thermosetting.

From Table 1, it can be seen that when a latex film is provided, the amount of impregnated resin deposited is large and it is difficult to flow out during heat curing.

Table 1 Comparative Example 1 The stator (1) was prepared in the same manner as in Example 1 except that the latex (6) was not dipped and the film was not formed.
4) to impregnate the coil (3) with the impregnating resin (4), and after impregnation, it was taken out and thermally hardened in a heating furnace.

Table 1 shows the amount of adhesive resin (4) adhered to the stator (1) after thermosetting.

Example 2 A latex for forming a film and a carboxylic acid for curing the latex were combined as shown in Table 2, and as shown in FIG. 5, 1. Various types of latex (manufactured by Nippon Zeon ■ unless otherwise specified) (6) were dropped onto the surface of the sample and brought into contact with the corresponding vapors of various carboxylic acids for 20° aXS seconds, and the thickness of the formed film was measured.

Table 2 shows the results.

Table 2 It can be seen from Table 2 that a film is formed in a short time in any combination of latex and carboxylic acid used.

Example 3 Using the combinations of latex and carboxylic acid shown in Table 2, various latexes (6) at 1° were dropped onto a glass plate (9) in the same manner as in Example 2, and then the corresponding various carboxylic acid solutions were added. The thickness of the formed film was measured by immersing it in 2oc1:I×5 seconds.

Table 6 shows the results.

Table 6 It can be seen from Table 6 that a film is formed in a short time even when immersed in a carboxylic acid solution, similar to when brought into contact with steam.

Example 4 The influence of temperature and contact time with carboxylic acid on film formation when using the combination of latex and carboxylic acid of Sample No. 4 in Table 2 was measured in the same manner as in Example 2.

The results are shown in Table 4.

Table 4 From Table 4, it can be seen that film formation is sufficient even at temperatures as low as -5°C, and at temperatures ranging from 0°C to 40°C, a contact time of 5 seconds or 60 seconds results in a film formation of 0.21°C, respectively.
It can be seen that a fast-curing film with a thickness of 1.30 mm to 1.30 mm was formed.

In addition, since a film can be formed even at low temperatures, the viscosity of the impregnated resin (4) impregnated into the coil (3) can be increased by cooling, and the film can be formed after it has flowed out. be.

[Brief explanation of the drawing]

Figures 1 to 4 are explanatory diagrams for sequentially explaining the steps of the present invention, in which Figure 1 is a perspective view of a stator, and Figure 2 is an explanation showing a state in which the stator is impregnated with impregnating resin. Figure 6 is an explanatory diagram showing a state in which a stator impregnated with impregnated resin is immersed in latex, and Figure 4 shows a state in which latex attached to the stator is hardened in acetic acid vapor. FIG. 5 is an explanatory diagram showing a state in which latex is dropped onto a glass plate to form a film. (Main symbols in the drawing) (1): Stator (2): Laminated core (3): Coil (4): Impregnated resin (5): Container (6) Nilatex (8): Partition plate 1 Figure 3 ' Figure 2 Procedural Amendment (Voluntary) 5.6゜11゛Indication of Governor's Palace and 1°If f'l
- No. 485013 No. 2 Bukomei's name Film forming method: (Mountain II 1- and Representative Kata Yuhito Part 4 Name of agent 493- Subject of amendment (1) Detailed description of the invention in the specification Contents of column amendment (1) “Fast brewing property” on page 2, line 18 of the specification was changed to “fast curing property”
to correct. that's all

Claims (5)

[Claims] (1) Changing the hydrogen ion concentration of an aqueous polymeric liquid as a means of film formation and sealing to prevent the leakage of a fluid liquid (impregnated resin) intended for electrical insulation of electrical equipment and electronic components. A film forming method characterized by curing the polymer by adding cations to the aqueous liquid of the polymer. (2) The aqueous polymeric liquid used as a means for forming and sealing a film to prevent leakage of a fluid liquid (impregnated resin) for the purpose of electrical insulation of electrical equipment and electronic parts;
A film forming method according to claim (1), characterized in that an emulsion is used. (3) The method for forming a film according to claim (1), characterized in that latex is used as the aqueous polymeric liquid used in the means for preventing outflow of the fluid liquid for the purpose of electrical insulation. (4) Claims (1) or (3) characterized in that acrylate latex, acrylonitrile-butadiene latex, or styrene-butadiene latex is used as the latex, and carboxylic acid is used as the curing means. Film forming method described in section. (5) The film forming method according to claim (4), characterized in that a monobasic carboxylic acid is used as the carboxylic acid.