JPS58141213A - Curing of thermosetting resin - Google Patents

Abstract

PURPOSE:To make it possible to bring a product to be cured to a curing temperature within a short time, to effect uniform curing and to obtain a thermoset resin especially useful as an electrical insulating material, by immersing a thermosetting resin in a liquid medium and curing the resin. CONSTITUTION:A thermosetting resin (a conventional resin which is cured by thermal energy, for example, an unsaturated polyester resin, especially one for use as electrical insulating material) is immersed in a liquid medium (a normally liquid medium such as water, or a normally solid medium which liquefies upon heating, such as wax) and then cured. The medium remaining on the surface of the thermoset product is washed, if desired, with a solvent harmless to the product or, in case of a normally solid medium, dripping on standing of the medium will suffice.

Description

[Detailed description of the invention] The present invention relates to a method of curing thermosetting resin.

More specifically, the present invention relates to a curing method useful for thermosetting resins for electrically insulating materials.

Conventionally, thermosetting resins have been cured by curing them in open hot air. With this method, it takes time for the material to be cured to reach the curing temperature.Due to the large temperature distribution during opening, the cured material does not harden uniformly, and the physical properties of the cured material may differ partially. There were disadvantages such as large heat loss. As a countermeasure to these problems, raising the oven temperature to improve curing properties was naturally limited by the heat resistance limits of the materials used.

In addition, in order to cure the thermosetting resin at a lower temperature than t, the use of a curing accelerator is required, so the pot life is shortened.
It had the disadvantage of poor workability. Furthermore, UV curing or UV curing combined with heat curing requires complicated and large-scale equipment, which increases the cost of the rounded resin, which requires an expensive sensitizer. There are 6 and 9 drawbacks such as skin irritation. This method of curing thermosetting resin is characterized by being simple and inexpensive, reaching the curing temperature in a short time, and curing uniformly.

F! as a thermosetting resin that can be used in the present invention! Conventional resins, which were conventionally hardened by thermal energy, can be used for their formulations, such as unsaturated 4-lyester resins. It is a composition of these mm and modified resins blended with liptadiene resin, polyurethane resin, urethane resin, silicone resin, acrylic resin, phenol resin, modified resins thereof, and various additives. It is particularly useful for thermosetting resins for electrical insulation materials.

naphtha, ethylene glycol, glopylene glycol,
mono- or polyether polyols, silicone oils, etc.; or solid substances that liquefy upon heating, such as wax, petroleum resins, polyethylene oxide, polyethylene, etc., or mixtures of the above liquid substances and solid substances; It is preferable to use a material with a good adhesiveness, and it is selected as appropriate, taking into account the material that does not inhibit curing, or the material that does not deteriorate the physical properties of the cured product by mixing with or reacting with the thermosetting resin, and also taking into account evaporation and decomposition during heating.

Also, be sure to remove any medium left on the surface of the cured product! The cured product may be washed with a solvent that does not inhibit the cured product, or if the medium is solid at room temperature, it may be sufficient to simply cut into 9 pieces.

With the curing method of the present invention, the curing temperature of the cured product can be reached in a short time, and the temperature distribution of the medium can be controlled to be small, making it possible to achieve uniform curing in a short time. Variations in physical properties of compounds are reduced. Furthermore, it is an excellent curing method with less loss of thermal energy than hot air open method.

The curing method of the present invention is particularly used for thermosetting resins for electrical insulation materials such as paints, adhesives, casting materials, and machine materials, as well as for general paints, casting, molding, adhesives, etc. It can also be used in fields where heat curing is required.

Particularly preferred specific parts include impregnated or cast varnish parts such as power transformers, capacitors, motors,
Various coiled parts such as ignition coils, magnetic switches, deflection yokes, ignition coils, cast resin parts such as cable joints, muO/AO co/verters,
Examples include various electrical components such as Do/DO converters, Mu0/DO inverters, and switching regulators.

When the curing method of the present invention is applied to coiled parts, there is no dripping prevention effect during curing, and in transformers, etc., the voids inside the transformer are reduced, improving heat radiation, preventing undulating, and improving thermal conductivity. This results in an improvement in the temperature rise prevention effect.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1. Comparative Example 1 An unsaturated polyester resin mixture was poured into a glass test tube, and a sample with a thermistor fixed in the center of the mixture was placed in rapeseed oil heated to 100°C (Example 1) and 100°C.
℃ hot air open (comparative example 1) for 4C, curing heat generation of unsaturated polyester resin -ll1lt- is shown in Figure 1. This test is based on JIS K-6901 [7
It was measured.

In Figure #I1, curves ll111 and ll1I2 show the curing heat generated in rapeseed oil and in the open, respectively, and it was shown that the curing method of the present invention cured in a shorter time.

Example 2 Comparative Example 2 A sample prepared by pouring a resin composition onto a flat iron plate was heated to 130°C and placed in crystal wax (Example 2).
) and 130111: Hot air open (comparative example 2) 4 pieces each of K were left and the lead chain hardness f was measured tjll
Good to show to lli.

Table 1 shows that the curing method of the present invention can significantly shorten the curing time, and the physical properties of the cured product are uniform.

Example 3. Comparative Example 3: A urethane resin compound was applied between steel plates, and J-Ko SK-6
850 were placed in silicone oil heated to 65°C (Example 3) and in hot air at 65°C (Comparative Example 3), and the tensile shear adhesive strength was measured. The results are shown in Table 2.

Table 2: A small heavy power supply transformer impregnated with a Liptazine resin compound and operated at 9136°C with a temperature fuse heated to a predetermined temperature (Example 4) and a predetermined temperature (Comparative Example 4) For each K4r measurement item, 4 pieces were left for each measurement item, heated and cured, and the transformer was disassembled to check the curing properties, whether or not the temperature fuse was broken, and the amount of varnish attached to the small lid power transformer, and whether the transformer was broken or not. The presence or absence of the source was tested.

These results are shown in Tables 3II to 6.

Table 3 (curability) Table 5 (varnish adhesion amount) No. 61K (Unari) (Note) Scooped with Ijjk needle From the results in Tables 3 to 6 above, the curing method of the present invention is suitable for linearization. It has been shown that it can significantly shorten the time, has the effect of preventing the resin from curing, and is excellent in eliminating the trouble of breaking the temperature fuse and preventing the melting.

[Brief explanation of drawings]

Figure 141 is a curing exothermic curve in Example 11 and Comparative Example 1. Patent applicant: Nippon Soda Co., Ltd. Representative: Haru Ito 2nd party
Yoshimi Yokoyama Figure 1 Stone history I O θ To wall 1 i (Shoulder\)

Claims (1)

[Claims] Curing a thermosetting resin by immersing it in a liquid medium'f
Method for curing thermosetting resin using TS mold.