JPS61279109A - Covering of electric part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of coating electrical components such as capacitors.

(Prior Art and its Problems) Conventionally, in order to protect and insulate electrical components such as capacitors, heat-shrinkable polyvinyl tubing has been covered. (7) In recent years, with the trend of miniaturizing components, capacitors and I
As the mounting density of C, etc. is increasing and the mounting interval is becoming narrower by one inch, the tube after coating will shrink again during the post-heating process such as the soldering process of adjacent parts. If there is a weak point in the pin pole, etc., the phenomenon will occur where the weak point will expand and cause a tear.

For this reason, if a heat-shrinkable IJJλA vinyl tube with a low shrinkage rate is used to make it difficult for the shrinkage reaction j) to occur in the post-heating process, insufficient shrinkage will occur during the coating process, resulting in poor appearance and There are many defective products whose dimensions are different from those shown.

However, when using thermoplastic polyvinyl chloride tubes that have been made flexible by adding a large amount of plasticizer to prevent weak points such as pinholes, shrinkage occurs at relatively low temperatures, so Problems such as natural shrinkage occur during tube production and distribution.

(Means for solving the problem) The present inventor has solved the problem by using a thermoplastic polyvinyl chloride tube to which a plasticizer (hereinafter referred to as a powder plasticizer) having a melting point of 1lo-70°C is added. The present invention was arrived at by discovering that the above-mentioned problems could be solved, and the gist thereof is that the melting point of
A heat-shrinkable tube made of a composition containing 6 to 6 parts by weight of a plasticizer at a temperature of 6 to 6 parts by weight and g to θ parts by weight of a plasticizer whose melting point is below 0'CJ is fitted onto an electrical component and heated. This is a method of covering electrical parts characterized by subjecting them to shrinkage testing.

As the polyvinyl chloride resin in the present invention, for example, those having an average molecular weight of gooJJ or higher can be suitably used.

The powder plasticizer may be one that is powder at room temperature with a melting point of 70°C, such as TPP (triphenyl phosphor), melting point lI9°C), DCHP (dicyclohexyl phthalate, M point A3.!), etc. ;0Q), DMI(
Dimethyl isophthalate (melting point O: 7°C), TSEP (tricetyl phosphite melting point +, 2°C), TSTP (tristearylphosphite melting point: SO°C), etc. can be used.

The amount of powder plasticizer added is polyvinyl chloride resin 10
If it is less than 0 parts by weight, it will not be possible to prevent breakage during the post-heating process, and if it exceeds -5 parts by weight, it will shrink even at low temperatures, causing problems in tube production and distribution. So, 4~. 25 parts by weight are required.

Melting point / 0' (:, downstream plasticizer (downstream liquid plasticizer)
For example, DOP or the like can be used, but if the amount added exceeds 1 part by weight, the shrinkage at low temperatures becomes large, so g to θ parts by weight are required.

The blending ratio of the powder plasticizer and the liquid plasticizer is such that the softening temperature (Kratschberg softening temperature) of the blended composition of the resulting polyvinyl chloride resin is in the range of 3 to 9 °C. This is preferable because it causes less tearing in the post-heating process and has less shrinkage at low temperatures, and conventional heating coating conditions can be applied to the breaking.

Further, the shrinkage rate of the heat-shrinkable polyvinyl chloride tube is preferably one that shrinks by 3 seconds to 5 ocks in the radial direction and λ to 10 times in the axial direction when immersed in water (10θ°C) for S minutes.

As coating processing conditions, for example, S~ from the outer periphery of the electrical component.
A heat-shrinkable polyvinyl chloride tube having a circumferential length larger than /3 is covered, and the shrink tunnel or hot air blowing at a hot air temperature of /gθ to 2Sθ° C. may be heated for 2 to 3 seconds in a furnace.

(Effects of the Invention) As mentioned above, the present invention includes 6 to aS weight parts of a powder plasticizer with a melting point of θ to 70°C, and optionally θ to g parts of a liquid plasticizer with a melting point of less than 0°C. The heat-shrinkable polyvinyl chloride tube added with the heat-shrinkable polyvinyl chloride tube is fitted onto the electrical component and heat-shrinkable coated, so there is little risk of tearing during the post-heating process, and the shrinkage at low temperatures is low, making production easier. There is also less problem of natural shrinkage during the distribution process.

= 4 Examples 1-7 and Comparative Examples/-G Examples/-7 have an average molecular weight of 10. To the polyvinyl chloride resin of tO, DOHP and TPP as powder plasticizers and liquid plasticizer DOP were added in the amounts shown in Table 1, and further stabilizers,
A blended composition to which weight parts of and pigments were added,
The material tube is melted and kneaded in an extruder, taken out from a nozzle with an inner diameter of 1 mm at 200°C, and cooled (-), then reheated to 100°C and stretched to an outer diameter of &A 7171, and a wall thickness of 0.
．． A heat-shrinkable tube with a length of 0.7 mm and a shrinkage rate of 7% in the longitudinal direction and 410% in the transverse direction when heated for 100° C.S minutes was prepared.

This heat-shrinkable tube has lengths g, s, and B7. Cut into
A cylindrical capacitor with a diameter of 1 mm and a length of 7 mm was covered with 100 capacitors each, and heated for 3.6 seconds in a shrink tunnel at a hot air temperature of 2/θ°C to shrink and cover.

In the same manner, coated capacitors were also obtained for the comparative examples shown in Table 7.

Table 1 shows the results of evaluating the following items for this coated capacitor.

Pinhole failure rate: A covered capacitor was poked with a dressmaking example No. G, a pinhole with a diameter of 0.7 mm was made in the covered tube, and the capacitor was left in a constant temperature bath at ambient temperature / gO ℃ for 10 minutes [-
Then, check the expansion state of the pinhole and find that the pinhole is J m
Items larger than m were considered defective and expressed as a defective rate (%) out of 100 pieces.

Coating finish: The axial length of the tube after coating is g mm or more◎,
? ,5. ．． 017. It was set as △ which is less than smm.

Low-temperature shrinkage properties: When the radial shrinkage rate was left at 30° C. and 30% RH for 10θhr, values of less than 2 coefficients and 013 coefficients or more were marked as ×.

Table 1 = 9- As shown in Table 1, Examples/~7 in which the powder plasticizer was added in a range of 3 parts by weight and the liquid plasticizer was added in a range of 3 parts by weight or less, The coating has a good finish, the pinhole defect rate is s-%j or less, and it has excellent low-temperature shrinkage characteristics.

On the other hand, in Comparative Example λ using only a liquid plasticizer, the pinhole defect rate was as high as 7 oes, and the coating quality was somewhat inferior due to a tendency to cause vertical shrinkage during coating. In addition, in Comparative Example 3 in which the powder plasticizer was less than 6 parts by weight, the pinhole defective rate λθ was not sufficient.

Furthermore, in Comparative Example G containing more than 26 parts by weight of the powder plasticizer, the softening temperature decreased to 39° C., and the low-temperature shrinkage characteristics deteriorated.

FIG. 1 shows shrinkage characteristic curves representing the relationship between the radial shrinkage rate and temperature of the heat-shrinkable polyvinyl chloride tubes of Example S and Comparative Examples.

A) shows a heating time of 5 seconds, and b) shows a heating time of 5 minutes.

According to this figure, Example S shows a larger shrinkage rate at around 70°C than Comparative Example 1 in a) where the heating time is short, so the temperature range that the tube surface reaches in the actual shrinking process is 70°C. Because of the close proximity, it shows good coverage in a short time. Dimensions. In a), the comparative example also has a high shrinkage rate at 7θ°C, but in b), which is heated for a long time, it shows considerable shrinkage even at temperatures as low as 470°C, so natural shrinkage occurs during the production and distribution process. easy.

On the other hand, looking at the curve of Example S, it shows sufficient shrinkage in a short period of time around 70°C, and also exhibits no natural shrinkage over a long period of time at relatively low temperatures.

Claims (1)

[Claims] Melting point 40-70 for 100 parts by weight of polyvinyl chloride
A heat-shrinkable tube made of a composition containing 6 to 25 parts by weight of a plasticizer with a melting point of 0°C or less and 8 to 0 parts by weight of a plasticizer with a melting point of 0°C or less is fitted onto an electrical component to provide a heat-shrinkable coating. A method for coating electrical parts, characterized by: