RU2537862C1 - Compound casting method for electrical goods - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: compound casting method for electrical goods includes mixing of components with receipt of the compound and casting of the electrical goods with the compound. At that before casting an electrical good is heated at temperature of 50-55°C and residual pressure of 10-15 mm hg at least during 3 hours. The compound is received by mixing of predried components in the following ratio, g: styrene - 50, castor oil - 38, product 102T - 12, benzoyl peroxide paste - 1. The paste made by mixing of predried benzoyl peroxide with dibutyl phthalate is used as the benzoyl peroxide paste. At that before casting the compound is vacuumised additionally at temperature of 15-35°C and residual pressure of 10-15 mm hg at least during 3-5 minutes. The pretreated electrical goods and compound are heated in the same furnace at temperature of 70°C during 1 hour. Then the heated electrical goods are casted step by step with the hot compound by the free casting method initially to ѕ of the electrical good height or volume with further vacuum degassing of the casted electrical goods at temperature of 15-35°C and residual pressure of 10-15 mm hg during 15-20 minutes with further casting of the electrical good with the same compound up to the required level. The multistage polymerisation of the compound is carried out. At that the casted electrical goods are held in the furnace heated up to 70°C during 4 hours at first, then they are casted with the same compound and its polymerisation takes place again at temperature of 70°C during 4 hours.

EFFECT: non-availability of defects in the form of cracks and air bubbles in the compound mass thus ensuring high quality of the casted electrical goods, and namely increasing their electric strength and reducing quantity of wastes.

Description

The invention relates to the field of electrical engineering and relates to a method of filling compound of electrical products, for example high-voltage transformers, or other products, which are a housing with a magnetic circuit and coil located inside, containing thin wires and fragile elements for electrical insulation and protection against climatic and mechanical influences.

A known method of producing an insulating polyurethane compound (see application for invention No. 94036678, IPC C09K 3/10, publ. 07/20/1996) by reacting castor oil as a hydroxyl-containing component and 2,4-toluene diisocyanate in the presence of an organic additive, followed by vacuum and polymerization. Initially, castor oil is brought into contact with an organic additive, which is used as methylbenzene, and then 2,4-toluene diisocyanate is introduced into the resulting mixture in the following ratio, wt.%:

Castor oil 59.5-75.2 methylbenzene 3.8-23.8 2,4-toluene diisocyanate 16.7-22.6,

polymerization is carried out at a temperature of 60-80 ° C.

Additionally, benzoyl peroxide in the amount of 0.5-1.0 wt.% Relative to the total amount of the composition is added to the composition. The method is selected as a prototype.

When pouring electrical products with a compound prepared according to the technology specified in the prototype, there is a high probability of formation of compound defects in the form of cracking or foaming, which affects the electrical parameters of the compound. The causes of defects are the insufficient degree of purification of the initial reagents from moisture, a non-optimal formulation (ratio of components and the concentration of initiator in the system) and the temperature regime of the process. In this regard, the method of pouring electrical products specified in the prototype is ineffective, it does not allow to obtain high-quality casting material with the necessary electrical insulation properties, which leads to an increase in the waste of flooded electrical products into the marriage in terms of "breakdown".

The objective of the proposed invention is to improve the quality of poured electrical products, i.e. improving the electrical insulation properties of the compound, namely increasing its electrical strength and, as a result, reducing product waste.

Effect: prepared and polymerized according to the proposed recipe and technology, the compound is an elastic monolithic rubber-like (without cracks, shells, bubbles) material that provides high electrical insulation properties.

The specified technical result is achieved by the fact that in the method of casting electrical products with a compound, including mixing the components to form a compound, casting electrical products with a compound, it is new that before heating the electrical items are additionally heated at a temperature of 50-55 ° C and a residual pressure of 10-15 mm RT. Art. in for at least 3 hours, additionally vacuum the compound at a temperature of 15-35 ° C and a residual pressure of 10-15 mm Hg within 3-5 minutes, where the compound is obtained by mixing additionally dried components from moisture, in the following ratio of components, g:

styrene fifty castor oil 38 product 102T 12 benzoyl peroxide paste one,

высоты или объема электроизделия с последующим вакуумированием залитых электроизделий при температуре 15-35°C и остаточном давлении 10-15 мм рт.ст. в течение 15-20 мин с последующим заполнением электроизделия этим же компаундом до необходимого уровня заливки, осуществляют ступенчатую полимеризацию компаунда, когда вначале залитые электроизделия выдерживают в разогретой до 70°C печи в течение 4 часов, затем повторно заливают электроизделия тем же компаундом и вновь проводят полимеризацию компаунда при температуре 70°C в течение 4 часов.where, as a benzoyl peroxide paste, a paste is used that is prepared previously by mixing the dried benzoyl peroxide with dibutyl phthalate in a ratio of 1: 1, then the prepared electrical products and the prepared compound are heated in a single furnace at a temperature of 70 ° C for 1 hour, and step-by-step filling of the heated electrical items with hot compound by the method of free pouring is carried out initially on $$\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$\mathrm{four}$}\right.$$

height or volume of electrical products, followed by evacuation of the filled electrical products at a temperature of 15-35 ° C and a residual pressure of 10-15 mm Hg for 15-20 minutes, followed by filling the electrical product with the same compound to the required fill level, stepwise polymerization of the compound is carried out, when initially the filled electrical products are kept in a furnace heated to 70 ° C for 4 hours, then the electrical products are re-filled with the same compound and again carried out polymerization of the compound at a temperature of 70 ° C for 4 hours.

Technical solutions with features distinguishing the claimed solution from the prototype are not known and do not follow explicitly from the prior art. This suggests that the claimed solution is new and has an inventive step.

We will consider the method of preparation and filling with a compound using high-voltage transformers as an example.

1. In the process of preparing the initial components of the compound carry out:

- additional monitoring of castor oil after drying for moisture content. In this case, the oil moisture should be no more than 0.05%. In case of obtaining the indicator "moisture content" of more than 0.05%, re-drying the oil;

- additional drying of the molten product 102T - 2,4-toluene diisocyanate with silica gel. To do this, the molten product is poured into a glass container with a tight-fitting lid filled with pre-dried silica gel (based on 100 ... 150 g of desiccant per 1 liter of product). Store the mixture at a temperature of 22 ... 30 ° C for not more than 1 month. Immediately before use, the product is filtered through a dry paper filter;

- additional washing of benzoyl peroxide. To do this, take a weighed portion of benzoyl peroxide in the delivery state in an amount of 50 g, grind it in a porcelain mortar, put in a bag of several layers of gauze and rinse with ethyl alcohol by dipping 3 times in a container with alcohol. The washed benzoyl peroxide is laid out in a thin layer on filter paper and dried in air for 10-12 hours.

These measures can improve the degree of purification of the starting components from moisture.

2. In the process of preparation, the proposed method provides a sequence for mixing the components of the compound, i.e. first, styrene is mixed in the first container with a benzoyl peroxide paste prepared previously by mixing the dried benzoyl peroxide with dibutyl phthalate (1: 1), the mixture is thoroughly mixed until the paste is completely dissolved in styrene. In the second tank, caster oil and the product 102T - 2,4-toluene diisocyanate are mixed, the mixture is also thoroughly mixed. Then the contents of the first container are poured into the second container with constant stirring. Mixing the resulting mixture is carried out until a homogeneous solution is obtained. The ratio of the components of the compound is as follows, g:

styrene fifty castor oil 38 product 102T 12 benzoyl peroxide paste one.

3. In the process of pouring high-voltage transformers, the proposed method provides:

- additional heating of the filled high-voltage transformers before casting at a temperature of 50 ... 55 ° C and a residual pressure of 10 ... 15 mm Hg for at least 3 hours;

- additional evacuation of the prepared compound before pouring at a temperature of 15 ... 35 ° C and a residual pressure of 10 ... 15 mm Hg within 3-5 minutes;

- heating of the prepared high-voltage transformers and the prepared compound in one furnace at a temperature of 70 ° C for 1 hour;

высоты или объема электроизделия с последующим вакуумированием залитых высоковольтных трансформаторов при температуре 15…35°C и остаточном давлении 10…15 мм рт.ст. в течение 15-20 мин, затем заполняют изделия этим же компаундом до необходимого уровня заливки;- step-by-step pouring of warmed high-voltage transformers with a hot compound by the free-casting method is carried out initially on $$\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$\mathrm{four}$}\right.$$

height or volume of electrical products, followed by evacuation of the molded high-voltage transformers at a temperature of 15 ... 35 ° C and a residual pressure of 10 ... 15 mm Hg for 15-20 minutes, then fill the product with the same compound to the desired fill level;

- stepwise polymerization of the compound is carried out, when initially the high-voltage transformers are kept in a furnace heated to 70 ° C for 4 hours, then the electrical products are re-filled with the same compound and the compound is polymerized again at a temperature of 70 ° C for 4 hours.

The compound prepared and polymerized according to the proposed formulation and technology is an elastic monolithic rubber-like (without cracks, shells, bubbles) material; the color of the compound can be from transparent amber to lemon yellow.

The method of preparation and pouring of the proposed compound eliminates the appearance of defects in the form of cracking and the appearance of air bubbles in the mass of the compound by increasing the degree of purification of the starting components, using the optimal ratio of components and temperature processing conditions. The method allowed to reduce the waste products in marriage from 50% to 0.5%.

Claims (1)

A method of casting electrical products with a compound, including mixing the components to produce a compound, casting electrical products with a compound, characterized in that prior to casting the electrical products are additionally heated at a temperature of 50-55 ° C and a residual pressure of 10-15 mm Hg for at least 3 hours, additionally vacuum the compound at a temperature of 15-35 ° C and a residual pressure of 10-15 mm Hg within 3-5 minutes, where the compound is obtained by mixing additionally dried components from moisture in the following ratio of components, g:
styrene fifty castor oil 38 product 102T 12 benzoyl peroxide paste one,
where a paste of benzoyl peroxide is used, a paste prepared previously by mixing the dried benzoyl peroxide with dibutyl phthalate, then the prepared electrical products and the prepared compound are heated in one oven at a temperature of 70 ° C for 1 hour, stepwise filling of the heated electrical products with a hot compound using the free casting method is carried out initially 3/4 of the height or volume of the electrical product, followed by evacuation of the filled electrical products at a temperature of 15-35 ° C and residual pressure nii 10-15 mmHg for 15-20 minutes, followed by filling the electrical product with the same compound to the required fill level, stepwise polymerization of the compound is carried out, when initially the filled electrical products are kept in a furnace heated to 70 ° C for 4 hours, then the electrical products are re-filled with the same compound and again carried out polymerization of the compound at a temperature of 70 ° C for 4 hours.