JPS6071626A - Electrically insulating composition - Google Patents

Abstract

PURPOSE:The titled composition that contains a polyurethane resin obtained from a mixed polyol of a polyol containing only the carbon atoms as the molecular main chain with castor oil polyol, and an organic polyisocyanate, thus having excellent coating film properties. CONSTITUTION:The objective composition is composed of a polyurethane resin obtained from the reaction between (A) a mixed polyol of (i) a polyol whose main chain contains only carbon atoms and has 2 or more hydroxyl in the molecule such as polybutadiene bearing hydroxylated terminals and (ii) castor oil polyol and (B) an organic polyisocyanate, when necessary, a catalyst, extender and other additives. USE:Casting and potting of electronic and electric parts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrically insulating compositions. Are electronic components exposed to humidity, dust, etc., or exposed to vibration and vibration? Jjffl
Insulating materials such as thermosetting epoxy resins, unsaturated polyester resins, and silicone resins have traditionally been used to protect electronic components from damage, allow them to fully perform their functions, and prevent malfunctions or deterioration. However, although thermosetting epoxy resins and unsaturated polyester resins have excellent mechanical properties such as impact resistance, they are vulnerable to heat shock and often crack due to rapid temperature changes, making products unreliable. Lacks sex.

Furthermore, in the case of silicone resin, it has drawbacks such as extremely high moisture permeability, which makes it impossible to apply it to electronic components whose characteristics change depending on humidity, and the unit cost of the material is high.

The present inventors have conducted extensive research to improve the above-mentioned drawbacks, and as a result, have come up with the present invention. That is, a mixture of a polyol whose molecular main chain is formed only of carbon atoms and has two or more hydroxyl groups in the molecule (hereinafter referred to as (a) polyol) and a castor oil polyol (hereinafter referred to as (b) polyol). This is an electrically insulating composition characterized by comprising a polyurethane resin obtained by reacting a polyol with an organic polyisocyanate compound.

Examples of the polyol (a) used in the present invention include hydroxyl-terminated liquid polybutadiene having two or more hydroxyl groups and mainly conjugated diene polymers.

Specifically, Po1y bd R-45HT (ARCO
), 8 Sodium PBG-2000, 8 Sodium PBG-3000
(all manufactured by Nippon Soda Co., Ltd.), polyether (manufactured by Mitsubishi Kasei Corporation), etc., as well as polyethylene polyols manufactured according to known manufacturing methods, such as conjugated dienes. Methods using organometallic compounds such as lithium compounds or by ping anion polymerization (Japanese Patent Publication No. 37-8190, Japanese Patent Publication No. 38-34
2), or the hydrogen peroxide method (Japanese Patent Publication No. 42-220
No. 48 Publication 111), azobisisonitrile compounds having hydroxyl groups (Japanese Patent Publication No. 38-5993),
There are polybutadiene polyols produced by radical polymerization using a peroxide compound having a hydroxyl group (Japanese Patent Publication No. 40-14747) as an initiator.

Furthermore, (a) polyols include acrylic polyols, polyethylene polyols, chloroprene polyols,
Examples include hydrolyzates of ethylene vinyl acetate copolymers.

The above (a) polyol has a hydroxyl value of 30■011/
g or less is preferable.

Examples of the polyol (b) include castor oil and its alkylene oxide adducts, transesterified products of castor oil with polyhydric alcohols, polyhydric alcohol esters, and the like.

The above (b) polyol has a hydroxyl value of 200 KOH/
g or less is preferable.

When the hydroxyl value exceeds 200 ■KOH/g, the compatibility with (a) polyol deteriorates.

Next, as an organic polyisocyanate compound, tolylene diisocyanate (hereinafter referred to as TDI) is used.

Crude diphenylmethane diisocyanate (hereinafter referred to as crude MDI), liquid diphenylmethane diisocyanate (hereinafter referred to as liquid MDI), hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate alone, or in combination with these polyisocyanates (
Examples include urethane prepolymers containing terminal NGOs, which are reaction products with a) polyols, (b) polyols, polytetramethylene ether glycols, polyester polyols, etc., alone or in mixtures.

In the composition of the present invention, the forming ratio of (a) polyol and (b) polyol is (a
It is preferable to use 90 to 10 parts by weight of the polyol (b) and 10 to 90 parts by weight of the polyol (b).

Further, the reaction ratio of the isocyanate compound to the mixed polyol is preferably such that the ratio of isocyanate groups to the hydroxyl groups of the mixed polyol ranges from 0.8 to 1.2.

The composition of the present invention may optionally contain polyols other than the polyols (a) and (b), such as trimethylolpropane, bisphenol A polyols, amine polyols, or alkylene oxide derivatives thereof.

Furthermore, the composition of the present invention may contain catalysts, fillers and other auxiliaries as required.

As the catalyst, organic metal compounds such as dibutyltin dilaurate, stannath octoate, dibutyltin diacetate, lead octylate, and lead naphthenate are used.

Extending agents include dioctyl phthalate, process oil, liquid petroleum resin, inorganic Z-iller, and the like.

Examples of the auxiliary agents include antifoaming agents, antifoaming agents, thinning agents, antioxidants, antiaging agents, ultraviolet absorbers, and colorants.

The composition obtained according to the present invention is extremely effective for casting, potting, dipping, coating, etc. of electronic and electrical parts.

Examples of the present invention are described below.

Reference Example (a) Production of polyol 70 parts of isopropanol was placed in a 500-liter autoclave.
1,3-butadiene 100 parts, 60% hydrogen peroxide Log
was charged and polymerization was carried out at 90°C for 5 hours. After cooling, unreacted monomers and hydrogen peroxide were distilled off under reduced pressure, and the resulting polymer was taken out and dried.

A polybutadiene polyol with a hydroxyl value of 90 KON/g was obtained in the same manner 6 and a hydroxyl value of 60 mgKOH/g
of polybutadiene polyol was obtained.

Example (a) Polyol and (b) polyol were mixed with liquid MDI in the proportions shown in Table 1, defoamed, poured into a mold approximately 3 m thick, heated at 80°C for 10 hours, and coated. Membrane physical properties and volume resistivity were measured.

Next, the coating film was immersed in distilled water at 80° C. for one month, and then the physical properties, volume resistivity, and water absorption of the coating film were measured in the same manner.

The results are shown in Table 1.

Claims (1)

[Scope of Claims] ('') A polyol whose main chain is formed only of carbon atoms and has two or more hydroxyl groups in the molecule (hereinafter referred to as (a) polyol), and a castor oil polyol (hereinafter referred to as (b)). 1. An electrically insulating composition comprising a polyurethane resin obtained by reacting a mixed polyol (referred to as a polyol) with an organic polyisocyanate compound.