JP2513471B2 - Electrical insulation material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric insulating material, and more particularly to an electric insulating material excellent in heat aging resistance.

[Prior Art and Problems to be Solved by the Invention] Conventionally, as an insulating material for a circuit board, for example, a composition comprising a liquid polybutadiene having a hydroxyl group and a polyisocyanate compound has been known. Since it is a material, it is generally used, for example, as a so-called potting material that is cast on a printed circuit board or as a so-called dipping material that dips the printed circuit board, and is then cured to obtain an insulating material.
However, the electrical insulating material composed of the above composition has a disadvantage that it is inferior in weather resistance and heat aging resistance.

Therefore, it has been proposed to use a hydride of the liquid polybutadiene instead of the liquid polybutadiene. When such a hydride of liquid polybutadiene is used, the weather resistance of the obtained insulating material is improved to some extent, but the skeleton of polybutadiene as a raw material of this hydride causes the following problems. That is, polybutadiene is 1,4
-When there are many addition type skeletons, the hydride becomes solid and the fluidity required as a potting material and dipping material cannot be obtained, while when there are many 1,2-addition type skeletons, the average number of functional groups is In each case, the heat aging resistance is not improved, and specifically, there is a problem that the volume resistivity decreases after heat history.

The present invention solves the conventional problems, and has a good fluidity as a potting material and a dipping material before curing, and an object of the invention is to provide an electrical insulating material having excellent heat aging resistance after curing. To do.

[Means for Solving the Problems] As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that when a hydride of liquid polyisoprene is used in place of a hydride of liquid polybutadiene, an excellent effect is obtained. The present invention was completed by confirming that the above was obtained.

That is, the electrical insulating material of the present invention is characterized by being obtained by curing a liquid polymer composition comprising a hydride of a liquid polyisoprene containing a hydroxyl group and a specific aromatic polyisocyanate compound.

As described above, the electrical insulating material of the present invention is a hydride of liquid polyisoprene containing a hydroxyl group (first essential component).
And a specific aromatic polyisocyanate compound (second essential component).

First, the liquid polyisoprene containing a hydroxyl group in the first essential component has a hydroxyl group in the molecule or at the molecular end, and has a number average molecular weight of 300 to 25,000, preferably 500.
~ 10,000 liquid polyisoprenes are used. here,
The content of hydroxyl group is usually 0.1 to 10 meq / g, preferably 0.3 to 7
It is meq / g.

Such liquid polyisoprene can be produced, for example, by heating and reacting isoprene in the presence of hydrogen peroxide in a liquid reaction medium.

Furthermore, the liquid polyisoprene having a hydroxyl group thus obtained is hydrogenated in the presence of a commonly used hydroxylation catalyst such as Ni, Co, Ru, Pt, and Rh to give the first composition of the present invention. A hydride of liquid polyisoprene containing a hydroxyl group, which is the essential component 1, is obtained.

Next, the polyisocyanate compound as the second essential component is an organic compound having two or more aromatic isocyanate groups in one molecule, and is a hydroxyl group of a hydride of liquid polyisoprene containing the hydroxyl group. To have a reactive isocyanate group. As such an aromatic polyisocyanate compound, tolylene diisocyanate, diphenylmethane diisocyanate (MDI) and liquid modified diphenylmethane diisocyanate are preferable.

The mixing ratio of the above-mentioned first and second essential components is not particularly limited, but is usually an isocyanate group (NCO) of a polyisocyanate compound with respect to a hydroxyl group (OH) of a polyisoprene hydride containing a hydroxyl group. The molar ratio (NCO / OH) is 0.2 to 25, preferably 0.5 to 15
So that

If desired, a polyol compound or a polyamine compound may be added to the composition as a reinforcing agent, and various other additives may be added.

As the polyol compound added as desired, any of primary polyol, secondary polyol, and tertiary polyol may be used. Specifically, for example, 1,2-propylene glycol, dipropylene glycol, 1,2-butanediol 1,3-butanediol, 2,3-butanediol, 1,2-
Pentanediol, 2,3-pentanediol, 2,5-hexanediol, 2,4-hexanediol, 2-ethyl-
At least one of 1,3-hexanediol, cyclohexanediol, glycerin, N, N-bis-2-hydroxypropylaniline, N, N'-bishydroxyisopropyl-2-methylpiperazine, propylene oxide adduct of bisphenol A, etc. The low molecular weight polyol containing a hydroxyl group bonded to the secondary carbon of

Further, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or the like that does not contain a hydroxyl group bonded to a secondary carbon can be used as the polyol. . Usually, a diol is used as the polyol,
Triol or tetraol may be used, and the molecular weight thereof is in the range of 50 to 500.

The polyamine compound may be diamine, triamine or tetraamine. Further, any of primary polyamine, secondary polyamine and tertiary polyamine can be used. As the polyamine compound, for example,
Aliphatic amines such as hexamethylenediamine; alicyclic amines such as 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane; aromatic amines such as 4,4'-diaminodiphenyl; 2,4,6- Examples thereof include tetramine such as tri (dimethylaminomethyl) phenol.

When these polyol compounds and polyamine compounds are compounded, the compounding ratio is not particularly limited, but usually 1 part of the polyol compound or polyamine compound is added to 100 parts by weight of the above-mentioned hydroxyl group-containing liquid polyisoprene.
To 1000 parts by weight, preferably 3 to 200 parts by weight.

Further, as other additives to be added as desired, for example, fillers such as mica, graphite, flint, calcium carbonate, slate powder and the like can be mentioned.

Furthermore, a plasticizer such as dioctyl phthalate may be added as a viscosity modifier, a softener such as an aroma-based, naphthene-based, or paraffin-based oil may be added. Tackifying resins such as phenolic resins, xylene formaldehyde resins, rosins, hydrogenated rosins, coumarone resins, aliphatic and aromatic petroleum resins can also be added. Further, a softening accelerator such as dibutyltin dilaurate, stannous octoate, or polyethylenediamine can be added. Furthermore, an anti-aging agent may be added to improve weather resistance, and a silicon compound or the like may be added as an antifoaming agent.

Furthermore, the electrical insulating material of the present invention can be produced by curing the liquid polymer composition thus obtained. The treatment temperature at this time is set to 0 to 200 ° C., preferably 15 to 150 ° C., and the treatment time is set to 0.5 to 75 hours, preferably 1 to 70 hours.

[Operation] Since the liquid polymer composition thus obtained has excellent fluidity, it can be cast on a substrate and then cured, or after the substrate is dipped in this composition. It can be cured or the like to form an electrically insulating region on the substrate. Therefore, the electrical insulating material of the present invention is used as an insulating material for a substrate of an electronic circuit or an electrical circuit, a molding material for a current transformer or a transformer, a molding material for a connecting portion such as a cable, an impregnated casting material for a transformer or a coil. It is useful, especially as an insulating material for electronic circuit boards.

[Example] Production Example 1 (Production of hydride of liquid polyisoprene having a hydroxyl group at the molecular chain end) In a pressure-resistant stainless steel reaction vessel having an internal volume of 1, 200 g of isoprene, 16 g of 50 wt% hydrogen peroxide solution and a solvent were added. Then, 100 g of sec-butyl alcohol was charged, and the reaction was carried out at a temperature of 120 ° C. and a maximum pressure of 8 kg / cm ² G for 2 hours. After completion of the reaction, the reaction liquid was extracted, 600 g of water was added thereto, and the mixture was shaken in a separating funnel and left standing for 3 hours. After separating the oil layer, 2m
After distilling at mHg and 100 ° C. for 2 hours, the solvent, the monomer and the low boiling point components were removed to obtain liquid polyisoprene having a hydroxyl group at the molecular end. The yield was 68%. The liquid polyisoprene has a number average molecular weight of 2150 and a hydroxyl group content of 0.
The viscosity was 96 meq / g and the viscosity was 56 poise at 30 ° C.

Next, 100 g of the liquid polyisoprene having a hydroxyl group at the molecular chain terminal obtained above was placed in the above-mentioned reaction vessel, 100 g of cyclohexane as a solvent and 5 wt% Ru-C catalyst.
10 g was charged, and hydrogen was introduced into this at a pressure of 50 kg / cm ² G. At this time, the temperature was 140 ° C. and the reaction time was 5 hours. After the reaction is completed, the reaction liquid is extracted, the catalyst is removed by vortexing with a membrane filter (0.45μ), and then the solvent is distilled off at a pressure of 2 mmHg and a temperature of 110 ° C. for 2 hours.
A desired hydride of liquid polyisoprene having a hydroxyl group at the terminal of the molecular chain was obtained. The obtained hydride had a number average molecular weight of 2210, a hydroxyl group content of 0.94 meq / g, an iodine value of 1 or less, and a viscosity at 30 ° C. of 383 poise.

Production Example 2 (Production of hydride of liquid polyisoprene having a hydroxyl group at the molecular chain end) The amount of hydrogen peroxide solution having a concentration of 50% by weight is 50 g, the amount of sec-butyl alcohol is 300 g, and the reaction temperature is 115 ° C. A liquid polyisoprene having a hydroxyl group at the molecular chain end was obtained in the same manner as in Production Example 1 except that the reaction time was 2.5 hours. This product had a number average molecular weight of 1380, a hydroxyl group content of 1.39 meq / g, and a viscosity at 30 ° C. of 23 poises.

Then, hydrogenation is performed under the same conditions as in Production Example 1 above,
A hydride was obtained. This product had a number average molecular weight of 1450, a hydroxyl group content of 1.36 meq / g, an iodine value of 1 or less, and a viscosity at 30 ° C. of 248 poise.

Production Example 3 (Production of hydride of 1,4-addition type liquid polybutadiene having a hydroxyl group at the molecular chain end) As a 1,4-addition type liquid polybutadiene having a hydroxyl group at the molecular chain end, Idemitsu Arco Co., Ltd., R -45HT (number average molecular weight: 2800, OH content: 0.82 meq / g, viscosity at 30 ° C: 50 poise, 1,4-addition type skeleton: 80 mol%, 1,2-addition type skeleton: 20 mol%) Was used to hydrogenate this to obtain a hydride. The hydrogenation conditions were the same as in Production Example 1 above except that the reaction time was 4.5 hours and that 500 ml of toluene was added after the reaction was completed. The obtained hydride had a number average molecular weight of 2920, an OH content of 0.80 meq / g, and was a waxy solid.

Production Example 4 (Production of hydride of 1,2-addition type liquid polybutadiene having a hydroxyl group inside the molecular chain) As 1,2-addition type liquid polybutadiene having a hydroxyl group inside the molecular chain, manufactured by Nippon Soda Co., Ltd., NISSO PB G-2000
(Number average molecular weight: 2,000, OH content: 0.85 meq / g, viscosity at 30 ° C .: 1930 poise) was used and hydrogenated in exactly the same manner as in Production Example 1 to obtain a hydride. The obtained hydride has a number average molecular weight of 20,080 and an OH content of 0.84 meq / g,
It was a highly viscous liquid and it was impossible to measure the viscosity at 30 ° C. using a B type viscometer.

Examples 1 to 3 and Comparative Examples 1 to 3 The indicated components were sampled in indicated amount containers and stirred at 25 ° C for 2 minutes to prepare liquid polymer compositions. Then,
This composition was poured into a mold and press-cured at 120 ° C. for 1 hour to obtain an electrically insulating material of the present invention.

The volume resistance and elongation at 25 ° C. of each of the obtained electric insulating materials were measured. Further, in order to examine the heat aging resistance, the physical properties after the heat aging test were measured, and the results are shown in the table.

[Effects of the Invention] As is clear from the above description, the electrical insulating material of the present invention has good fluidity before curing, excellent electrical insulating properties after curing, and thermal fatigue resistance. It also has excellent characteristics. Therefore, it is useful as a potting material or a dipping material, especially as an insulating material for electronic circuit boards, and its industrial value is extremely large.

Claims (2)

(57) [Claims] 1. A liquid polymer composition comprising a hydrogenated liquid polyisoprene having a hydroxyl group and at least one polyisocyanate selected from tolylene diisocyanate, diphenylmethane diisocyanate and liquid modified diphenylmethane diisocyanate. An electrically insulating material characterized in that 2. The electric insulating material according to claim 1, wherein the electric insulating material is an insulating material for electronic circuit boards.