JP5319206B2 - Insulating structural materials - Google Patents

Description

The present invention relates to an insulating structure material used when manufacturing epoxy resin castings such as bushings and insulating spacers, unsaturated polyester resin moldings, sealing insulators, and the like used for power devices and power distribution devices.

  Thermosetting resins have excellent insulating properties, mechanical properties, heat resistance, chemical resistance, weather resistance, and the like, and are widely used as insulating materials in the power field and semiconductor field. However, since it has excellent durability, it has been difficult to reuse and disassemble and dispose of it as a waste at the stage of disposing of such insulating material after enduring use for many years. In addition, insulating materials that have been relied on oil and added new functions are required.

In response to such a demand, an insulating structure material in which an organic filler made of a cellulose derivative or a hemicellulose derivative using a wood resource as a starting material is added to an epoxy resin or the like has been proposed (for example, see Patent Document 1). Moreover, what suppresses the fall of the electrical property and mechanical property by adding an organic filler is proposed (for example, refer patent document 2).
JP 2004-171799 A (pages 4-6, FIG. 1) JP 2008-53174 A (pages 3 to 5, FIG. 1)

  The above conventional insulating structural materials have the following problems. Biomass materials made of wood resources contain a large amount of long fibrous polymers having many hydroxyl groups such as cellulose derivatives and hemicellulose derivatives. For this reason, hydroxyl groups attract each other between adjacent molecular chains, and fluidity decreases. When such an organic filler is added to a thermosetting resin such as an epoxy resin, the viscosity increases, making the casting operation difficult. For example, when 30 parts by weight of the organic filler is added to 100 parts by weight of the epoxy resin, it becomes a bowl shape, and it is difficult to pour the insulating structure material into the casting mold.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an insulating structure material that can suppress an increase in viscosity even when an organic filler is added and can facilitate casting work.

In order to achieve the above object, the insulating structural material of the present invention is added with an organic filler having a particle size of 0.1 to 200 μm composed of a cellulose derivative and a hemicellulose derivative obtained by converting and purifying wood resources, and the organic filler. The organic filler is subjected to an oligoesterification treatment, and more than the matrix resin.
And 200% by mass or less .

  According to the present invention, since the oligoester-treated organic filler is added to the matrix resin, an increase in the resin viscosity when these are mixed can be suppressed, and the casting operation can be facilitated.

(Configuration of insulating structural materials)
The structure of the insulating structural material is shown in FIG. As shown in FIG. 1, the insulating structural material 1 is obtained by dispersing an organic filler 3 using a wood resource as a starting material in a thermosetting matrix resin 2.

  Examples of the thermosetting matrix resin 2 include an epoxy resin, a melamine resin, an unsaturated polyester resin, a polyimide resin, and a phenol resin that are used as an electrical insulating material. A thermoplastic matrix resin such as polyethylene resin can also be used. Here, the thermosetting resin and the thermoplastic resin are simply referred to as a matrix resin.

(Method for producing organic filler 3)
The manufacturing method of the organic filler 3 is shown in FIG. As shown in FIG. 2, first, a wood raw material is converted and purified by high-pressure hydrothermal treatment to obtain a cellulose derivative and a hemicellulose derivative (st1). The conditions for the high-pressure hydrothermal treatment are a temperature of 170 to 200 ° C., preferably 190 ° C., and a pressure of 1.8 to 2.2 MPa, preferably 2.0 MPa. Under these conditions, the oligosaccharide content in the wooden filler is reduced. Decompose. As the woody material, vegetative plants such as corn cob, rice straw and wheat straw are used. In addition, although there exists decomposition | disassembly by concentrated sulfuric acid as a method of obtaining a cellulose derivative, sulfur is added to the terminal part of a cellulose derivative, and there exists a concern about the bad influence on various characteristics.

  Next, the obtained cellulose derivative is dried and then pulverized and classified (st2). When the size (particle diameter) is 0.1 to 200 μm, preferably 1 to 100 μm, more preferably 5 to 70 μm, the dispersion becomes uniform and the mechanical properties can be improved. If it exceeds 200 μm, it acts like a foreign substance in the thermosetting matrix resin 2 and becomes a starting point of stress concentration, thereby reducing the mechanical properties. If it is less than 0.1 μm, the viscosity increases when mixed with the thermosetting matrix resin 2 and the workability deteriorates.

  Next, the classified cellulose derivative is subjected to oligoesterification in an acid anhydride as a solvent (st3). The chemical reaction process of the oligoesterification treatment is carried out by reacting the organic filler 3 with an acid anhydride such as maleic anhydride, phthalic anhydride, succinic anhydride, etc., so that a carboxyl group ( COOH) is added and further reacted with an epoxide compound to form a structure having a hydroxyl group (OH) in the side chain.

(Production example of insulating structural material)
The structural formula of cellulose obtained by decomposing and purifying woody resources as a starting material is shown in Formula (1). In the formula (1), cellulose is obtained by binding (1 → 4) -β-glucoside with glucose as a unit. The cellulose straight chain contains a large amount of hydroxyl groups derived from the glucose skeleton, generates hydrogen bonds between adjacent cellulose chains, and exists in a crystalline state. n is a positive integer.

Next, in order to break this hydrogen bond once, the cellulose on the left side shown in Formula (2) is reacted with the acid anhydride on the right side to be esterified.

Furthermore, as shown in the formula (3), when reacted with an epoxide, the epoxide is alternately added to the acid anhydride to generate an oligoester chain having a polymerizable double bond. n is a positive integer. Here, such a reaction is carried out without isolating the intermediate and is oligoesterified in one step. The reaction unit for oligoesterification is 1 or 2.

The oligoesterified organic filler 3 contains 5 to 200 mass% with respect to the resin component of the insulating structural material 1. The structural formula of the thermosetting matrix resin 2 is shown in Formula (4). Bisphenol A type epoxy resin and methyltetrahydrophthalic anhydride are used. n is 0 or a positive integer. The structural terminal of the epoxy resin has an epoxy group, and when heated in the presence of a suitable catalyst such as an amine, ring-opening polymerization is initiated with methyltetrahydrophthalic anhydride. The hydroxyl group present in the epoxy resin affects the crosslinked structure of the resin. Similarly, the hydroxyl group of the cellulose esterified is also present in the resin curing reaction.

  The insulating structural material 1 manufactured using the organic filler 3 that has been classified into a predetermined size and subjected to the oligoesterification in this way is unlikely to increase in viscosity, and casting work such as when filling a casting mold. Can be made easy. In addition, cast products that have been heat-cured can be microbially decomposed for a long time when soil is buried.

(Other production examples of insulating structural materials)
In order to simplify the insulating structural material 1, the system in which only the organic filler 3 is filled in the thermosetting matrix resin 2 has been described, but in addition to this, an inorganic filler or rubber particles can be added. Examples of the inorganic filler include those used as an electrical insulating material such as silica, alumina, mica, and titanium oxide. Moreover, additives, such as surfactant, an antifoamer, and a hardening accelerator, can be added. Thereby, the insulating structure material 1 which is excellent in various characteristics and facilitates the casting operation can be obtained.

  In the case where the thermosetting matrix resin 2 is an epoxy resin, an epoxy resin compounding main agent with or without an additive and a curing agent compounding agent with or without an additive are separately prepared and insulated. Both compounds can be mixed and used during the casting process to produce the part. As described above, the present invention naturally includes various implementations not described herein.

  150 parts by weight of the organic filler 3 that has been oligoesterified by the procedure shown in FIG. 2, 100 parts by weight of a bisphenol-type epoxy resin, and an anhydrous oxide curing agent (trade name: Kayahard (MCD) manufactured by Nippon Kayaku Co., Ltd.) 86 parts by weight and 0.8 parts by weight of an amine-based curing accelerator were added and mixed with a self-revolving mixing stirrer. Next, the obtained mixed resin was heated and defoamed, then poured into a casting mold preheated to a temperature of 80 ° C., and was primarily cured at a temperature of 80 ° C. for 15 hours. After releasing from the mold, it was placed in a heating furnace having a temperature of 150 ° C. for 15 hours and secondarily cured to obtain a cast product.

  Thus, the oligoester-treated organic filler 3 is improved in compatibility with the epoxy resin and can be added in a large amount. That is, the amount of the organic filler 3 can be larger than that of the thermosetting matrix resin 2. The cast product that had been heat-cured had a good external shape, and the electrical characteristics and mechanical characteristics were equivalent to or higher than those without the addition of the organic filler 3. Moreover, since the organic filler 3 can be added in a large amount, microbial degradation can be surely promoted.

(Comparative example)
Using the organic filler 3 not subjected to the oligoesterification treatment, an attempt was made to produce a mixed resin similar to the example. However, when 90 parts by weight of the organic filler 3 was added, the viscosity increased, making it difficult to produce a mixed resin suitable for casting.

  According to the insulating structure material of the above example, the mixed resin to which the organic filler 3 made of the oligoesterified cellulose derivative and hemicellulose derivative is added can suppress an increase in viscosity and facilitate the casting operation. Can do.

The cross-sectional schematic diagram which shows the structure of the insulation structural material which concerns on the Example of this invention. The flowchart figure which shows the manufacturing process of the organic filler which concerns on the Example of this invention.

Explanation of symbols

1 Insulating structural material 2 Thermosetting matrix resin 3 Organic filler

Claims (1)

An organic filler having a particle size of 0.1 to 200 μm comprising a cellulose derivative and a hemicellulose derivative obtained by converting and purifying wood resources;
A thermosetting matrix resin to which the organic filler is added,
While performing an oligoesterification treatment on the organic filler,
An insulating structure material added in a larger amount than the matrix resin and not more than 200% by mass .

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