JP4387786B2 - Epoxy resin composition and cast insulator - Google Patents

Description

  The present invention relates to an epoxy resin composition and a casting insulator, and more particularly, to a casting epoxy resin composition capable of expressing mechanical properties and heat resistance suitable as an insulating material or a structural material for electrical equipment and electrical components. . The epoxy resin composition of the present invention is particularly suitable for an insulating member such as an insulating support for a gas-insulated switchgear, a pipe-in-air power transmission device, or other electrical equipment, or an insulating spacer between electrical members.

  Epoxy resins have excellent mechanical properties, electrical properties, and adhesive properties, so IC substrates for electronic devices, sealing materials, molding materials for industrial and heavy electrical equipment, impregnation materials, insulating materials As widely used. In such applications, various performances such as better insulation, high thermal conductivity, heat resistance, mechanical properties, electrical properties, adhesion, high toughness, gas barrier properties, and high elasticity are required. In order to compensate for such performance, an epoxy resin is filled with an inorganic compound such as silica, alumina, or boron nitride.

  By the way, in recent years, attempts have been made to improve various properties such as fracture toughness, mechanical strength, heat resistance, and gas barrier properties of the thermoplastic resin by dispersing the layered clay compound in a thermoplastic resin such as polyamide (for example, And Patent Documents 1 to 8). In these prior arts, in order to uniformly disperse the layered clay compound in the thermoplastic resin, a slurry solution in which the layered clay compound is dispersed is prepared, and the slurry solution is mixed with a thermoplastic resin such as polyamide, or A technique of melt-mixing a layered clay compound into a thermoplastic resin such as polyamide using a biaxial extrusion mixer is used.

  However, in the dispersion method using the slurry solution, it is necessary to remove the dispersion solvent of the slurry solution during the production process, which may lead to an increase in production cost. The dispersion by the above melt mixing is an effective method only for a thermoplastic resin such as polyamide that melts by applying heat, and is not suitable for a thermosetting resin such as an epoxy resin that cannot be melted by heat. is there.

Further, in order to improve the mechanical properties such as bending strength of the glass fiber reinforced composite material, in order to increase the elastic modulus of the matrix resin such as epoxy resin, it is known to add a layer-like silicate compound to an epoxy resin ing. However, with this method, the layered silicate compound cannot be uniformly dispersed in the matrix resin, and the layer structure of the layered silicate remains retained. In such a dispersed state, the inherent properties of the layered silicate compound cannot be exhibited sufficiently.
Japanese Patent Laid-Open No. 11-181309 JP 11-315204 A JP 11-310702 A JP 11-92677 A JP-A-11-92594 Japanese Patent Laid-Open No. 10-324810 Japanese Patent Laid-Open No. 10-158431 Japanese Patent Laid-Open No. 9-11116

  Accordingly, an object of the present invention is to provide an epoxy resin composition having excellent mechanical properties and heat resistance by dispersing a layered clay compound in an epoxy resin with high dispersibility.

  The inventors of the present invention can improve the properties of the epoxy resin such as mechanical properties and heat resistance with a relatively small addition amount of the layered clay compound, but the layered clay compound is not uniformly dispersed in the epoxy resin. For example, in terms of mechanical strength, it has been found that agglomeration of layered clay compounds is the starting point and breakage progresses, which may cause a decrease in strength. As a result of further investigation based on this knowledge, it was found that the intended purpose was achieved by dispersing the layered clay compound in the epoxy resin in a state of delamination, and the present invention was completed.

That is, according to the first aspect of the present invention, (a) at least one kind of epoxy resin that is solid at normal temperature and at least one kind of epoxy resin that is liquid at normal temperature, each having two or more epoxy groups per molecule. An epoxy resin containing, (b) a curing agent for epoxy resin, and (c) a layered clay compound having a quaternary ammonium ion between layers, wherein the layered clay compound is mixed and peeled in the solid epoxy layer An epoxy resin composition is provided in which a solid epoxy resin dispersed and dispersed in a state where the layered clay compound is mixed and peeled is mixed with the liquid epoxy resin .

  Moreover, according to the 2nd side surface of this invention, the casting insulator which uses the epoxy resin composition of this invention is provided.

  The epoxy resin composition of the present invention has excellent mechanical characteristics and heat resistance characteristics as compared with epoxy resins used as conventional casting resins. For this reason, the use of the epoxy resin composition of the present invention as an insulating material facilitates the design of a gas-insulated switchgear, a pipeline air power transmission device, or other electrical equipment, and reduces the size and reliability of the equipment. Therefore, it can be said that the industrial value is extremely large.

  The epoxy resin composition according to the present invention includes (a) an epoxy resin having two or more epoxy groups per molecule, (b) a curing agent for epoxy resin, and (c) a layered clay compound.

  First, the epoxy resin used in the epoxy resin composition of the present invention is a curable compound having two or more three-membered rings (epoxy groups) consisting of two carbon atoms and one oxygen atom in one molecule. The type is not limited. Examples of such epoxy resins include bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, hydrogenated bisphenol A types obtained by condensation of epichlorohydrin with polyhydric phenols such as bisphenols or polyhydric alcohols. Epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, novolac type epoxy resin, phenol-novolac type epoxy resin, orthocresol -Glycidyl ether type epoxy resins such as novolac type epoxy resin, tris (hydroxyphenyl) methane type epoxy resin, tetraphenylolethane type epoxy resin, epichlorohi Glycidyl Jijiru ester epoxy resins obtained by condensation of phosphorus and Garubon acid, a heterocyclic epoxy resin such as a hydantoin type epoxy resin obtained by the reaction of triglycidyl isocyanate or epichlorohydrin with hydantoins. These epoxy resins can be used as a mixture of two or more.

  In the present invention, the epoxy resin includes an epoxy resin that is solid at room temperature (25 ° C.) (sometimes referred to as “solid epoxy resin” in this specification) and an epoxy resin that is liquid at room temperature (25 ° C.) (this specification). In some cases, it may be referred to as “liquid epoxy resin”). For example, in the case of a commercially available general-purpose bisphenol A type epoxy resin (trade name: Epicoat manufactured by Japan Epoxy Resin Co., Ltd.), the epoxy equivalent indicating the number of grams of a resin containing 1 gram equivalent of an epoxy group is 450 or more, or a weight average An epoxy resin having a molecular weight of 900 or more is solid at room temperature, and an epoxy resin having an epoxy equivalent of 270 or less or a weight average molecular weight of 470 or less is liquid at room temperature.

  The kind of the curing agent for epoxy resin is not particularly limited as long as it is capable of chemically reacting with the epoxy resin and curing the epoxy resin. Examples of such curing agents include diethylenetriamine, triethylenetetramine, metaxylylenediamine, isophoronediamine, 1,3-bisaminomethylcyclohexane, diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, dicyandiamide, organic acid dihydrazide. Amine curing agents such as phthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, tetrabromophthalic anhydride, nadic anhydride, methylnadic anhydride Acid anhydrides such as acid, trimellitic anhydride, pyromellitic anhydride, anhydrous head acid, methyl hymic anhydride, dodecenyl succinic anhydride, polyazelenic anhydride, benzophenone tetracarboxylic acid, etc. Agents, imidazole curing agents such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, polymercaptan curing agents such as polysulfide, thioester, polyamide curing agent, phenolic curing agent, Lewis Examples thereof include acid-based curing agents and isocyanate-based curing agents. These curing agents can be used alone or as a mixture of two or more. In particular, an acid anhydride curing agent is desirable as a curing agent for the epoxy resin composition of the present invention because of its long pot life and small heat generation during curing.

The layered clay compound blended in the epoxy resin composition of the present invention is composed of a sheet (silicate layer) in which SiO ₄ tetrahedrons are arranged two-dimensionally, and has a structure in which these sheets are laminated. In an ordinary layered clay compound, interlayer cations such as alkali metal ions, alkaline earth metal ions, and ammonium ions are present between silicate layers.

  In the present invention, the layered clay compound can be preferably selected from the group consisting of a smectite group, a mica group and a vermiculite group. Examples of the layered clay compound belonging to the smectite group include montmorillonite, hectorite, saponite, sauconite, beidellite, stevensite, and nontronite. Layered clay compounds belonging to the mica group include muscovite, biotite, paragonite, levitrite, margarite, clintonite, anandite, chlorite, phlogopite, lipidite, mascobite, biotite, paragonite, margarite, teniolite. And tetrasilicic mica. Examples of the layered clay compound belonging to the vermiculite group include trioctahedral vermiculite and dioctahedral vermiculite. Among these layered clay compounds, a layered clay compound belonging to the smectite group is desirable from the viewpoint of dispersibility in an epoxy resin. These layered clay compounds can be used alone or as a mixture of two or more.

  By the way, these layered clay compounds can hold various substances such as other ions, molecules, clusters, etc. between the layers by ion exchange with the cations that are usually present. In the present invention, it is preferable to insert an organic compound capable of imparting an affinity for the epoxy resin to the layered clay compound between the layers of the layered clay compound. As such an organic compound, quaternary ammonium ions are desirable in consideration of the degree of interlayer insertion by ion exchange treatment. Quaternary ammonium ions include tetrabutylammonium ion, tetrahexylammonium ion, dihexyldimethylammonium ion, dioctyldimethylammonium ion, hexatrimethylammonium ion, octatrimethylammonium ion, dodecyltrimethylammonium ion, hexadecyltrimethylammonium ion, stearyl Trimethylammonium ion, dococenyltrimethylammonium ion, cetyltrimethylammonium ion, cetyltriethylammonium ion, hexadecylammonium ion, tetradecyldimethylbenzylammonium ion, stearyldimethylbenzylammonium ion, dioleyldimethylammonium ion, N-methyldiethanol Uryl ammonium ion, dipropanol monomethyl lauryl ammonium ion, dimethyl monoethanol lauryl ammonium ion, polyoxyethylene dodecyl monomethyl ammonium ion, dimethyl hexadecyl octadecyl ammonium ion, trioctyl methyl ammonium ion, tetramethyl ammonium ion, tetrapropyl ammonium ion, etc. Can be mentioned. These quaternary ammonium ions can be used alone or as a mixture of two or more.

  By inserting a quaternary ammonium ion, the interlayer distance can be increased and the interlayer can be made oleophilic, so the affinity for the epoxy resin is improved and the epoxy resin can be more uniformly dispersed. . Therefore, excellent mechanical properties and heat resistance can be imparted to the epoxy resin.

  Further, it is more desirable that the quaternary ammonium ions existing between the layers of the layered clay compound have a predetermined functional group. Such functional groups include ether groups, sulfide groups, ester groups, amide groups, hydroxyl groups, carboxyl groups, carbonyl groups, aldehyde groups, epoxy groups, amino groups, nitrile groups, thiol groups, sulfonic acid groups, halogen groups, An unsaturated hydrocarbon group etc. can be illustrated. Such a functional group has high chemical activity. Moreover, since the glycidyl ring which an epoxy resin has also has very high activity, it becomes possible to cause interaction or a chemical reaction between these functional groups and an epoxy resin. For example, a hydroxyl group opens an glycidyl ring of an epoxy resin to form an ether bond, and an oligomer in which a quaternary ammonium ion and an epoxy resin are linked is generated. This oligomer reacts again with the quaternary ammonium ion or the epoxy resin, thereby forming a three-dimensional network structure in which the molecular chain of the epoxy resin is constrained by the silicate layer of the layered clay compound. Thereby, the layered clay compound serves as a reinforcing material for the epoxy resin, exhibits excellent fracture strength in a bending test, and can maintain an elastic modulus comparable to room temperature even in a high temperature region.

  The epoxy resin composition of the present invention can contain an epoxy resin curing accelerator. When an acid anhydride is used as a curing agent for an epoxy resin, a tertiary amine or a salt thereof, a quaternary ammonium compound, imidazole, or an alkali metal alkoxide is suitable as a curing accelerator.

  When the quaternary ammonium ion is inserted between the layers of the layered clay compound, the epoxy resin curing accelerator can shorten the gelation time of the epoxy resin composition as the amount added is increased. That is, the curing reaction rate of the epoxy resin can be controlled by the amount of the curing accelerator for the epoxy resin.

  The quaternary ammonium ion inserted between the layers of the layered silicate is similar in chemical structure to the curing accelerator for epoxy resin, and has the effect of promoting the curing reaction of the epoxy resin. When the layered clay compound is delaminated and the exfoliated silicate layer is uniformly dispersed in the resin, the quaternary ammonium ions inserted between the layers are dispersed in the resin. It acts as a curing accelerator, speeds up the curing reaction of the resin, and shortens the gel time. In other words, the effect of quaternary ammonium ions inserted between layers of a layered clay compound when a layered clay compound having a quaternary ammonium ion between layers is intended to impart excellent mechanical properties and heat resistance to an epoxy resin. This makes it difficult to control the curing reaction.

  In recent years, in the production of an insulating material by casting using an epoxy resin, a pressure gelation method is often employed in order to improve mass productivity. In this method, the temperature of the casting mold is made higher than the temperature of the casting resin, and a certain temperature gradient is applied to the mold, and then the casting resin is applied to the mold while applying a certain pressure from below the mold. Inject inside. Furthermore, after the casting resin is completely filled in the casting mold, the casting resin is quickly cured at a high temperature with a certain pressure applied. In this method, it is necessary to control the rate of the curing reaction (gel time) by the temperature of the casting mold and the resin composition. For example, if the speed of the curing reaction is fast (the gel time is short), the resin is cured before the mold is filled with the resin, and a predetermined casting cannot be manufactured. In the epoxy resin composition of the present invention, since the rate of the curing reaction (gelation time) can be controlled by the amount of the curing accelerator, it can be applied to the production of cast insulators by the pressure gelation method. it can. In addition, in addition to the solid epoxy resin used for dispersion | distribution of a layered clay compound, when using a liquid epoxy resin, hardening time can also be adjusted with the usage-amount of a liquid epoxy resin.

  Furthermore, the epoxy resin composition of the present invention can contain a dispersion aid in order to improve the dispersibility of the layered clay compound or suppress reaggregation of the dispersed layered clay compound. Examples of such dispersion aids include ketones, alcohols, polar solvents, surfactants, amphiphilic compounds, silane coupling agents, and the like. More specifically, examples of ketones include acetone and methyl ethyl ketone. Examples of alcohols include methanol, ethanol, propyl alcohol, isopropyl alcohol and the like. Examples of the polar solvent include dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, acetonitrile and the like. Surfactants and amphiphilic compounds include sodium dodecyl sulfate, sodium n-dodecylbenzenesulfonate, bis (sodium 2-ethylhexylsulfosuccinate) (Aerosol OT), sodium oleate, sodium polyacrylate, sodium alginate, carboxymethylcellulose (CMC), sodium polyphosphate, sodium hexametaphosphate, cetyltrimethylammonium bromide (CTAB) and the like. Examples of silane coupling agents include γ-glycidoxy-propyltrimethoxysilane, γ-aminopropyl-trimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-glycidyloxypropyl-trimethoxysilane. It can be illustrated. These dispersion aids can be used alone or as a mixture of two or more.

  By adsorbing the surfactant or amphiphilic compound on the surface of the layered clay compound, the absolute value of the zeta potential of the layered clay compound can be increased. In general, the surface of inorganic fine particles such as layered clay mineral, silica, alumina, boron nitride, and metal oxide is electrostatically charged, and the magnitude of the charge is expressed by zeta potential. If the absolute value of the zeta potential is large, an electrostatic repulsive force acts between the fine particles and it becomes difficult to aggregate, so that the layered clay compound can be uniformly dispersed in the epoxy resin. Further, in one embodiment of the present invention, the layered clay compound is subjected to high shear stress in the solid epoxy resin, and the layered clay mineral is peeled and dispersed between the layers, and then mixed with the liquid epoxy resin. The epoxy compound is cured with a curing agent and an epoxy resin curing accelerator depending on the case. In the step of mixing with the liquid epoxy resin, the layered clay compound dispersed in the solid epoxy resin may gather and aggregate again. The dispersion aid disperses the layered clay compound in which the quaternary ammonium ions are present between the layers very well in these dispersion aids, so that the dispersibility is improved by adding them in the resin. be able to. These actions make it possible to disperse the layered clay compound more uniformly in the epoxy resin, and the dispersed layered clay compound promotes the effect of reinforcing the polymer chains constituting the higher order structure of the epoxy resin. be able to. Furthermore, the silane coupling can also improve the adhesion between the layered clay compound and the epoxy resin. Thereby, the adhesive interface between the layered clay compound and the resin in the cured resin becomes strong, and an insulating material having excellent mechanical strength can be obtained.

  In the epoxy resin composition of the present invention, the layered clay compound (c) is preferably contained at a ratio of 1 to 30 parts by weight per 100 parts by weight of the epoxy resin (a). Moreover, it is preferable that the hardening | curing agent (b) for epoxy resins is contained in the ratio of 80-100 weight part per 100 weight part of epoxy resins. Furthermore, it is preferable that a hardening accelerator (d) is contained in the ratio of 0.1-1 weight part per 100 weight part of epoxy resins. Moreover, it is preferable that a dispersion | distribution adjuvant is contained in the ratio of 0.1-1 weight part per 100 weight part of layered clay compounds (b).

  As described above, the epoxy resin composition of the present invention is dispersed in a state where the layers are separated. In FIG. 1, the internal structure of the epoxy resin composition which concerns on one embodiment of this invention is shown typically. As shown in FIG. 1, the layered clay compound is delaminated, and the exfoliated silicate layer 12 enters between the molecular chains 11 of the epoxy resin and serves as a reinforcing material that restrains the three-dimensional network structure of the cured epoxy resin. . Therefore, the bending fracture strength of the obtained cured product increases, and the room temperature elastic modulus can be maintained even in a high temperature region.

  In order to disperse the layered clay compound in the epoxy resin in the state where the layer is peeled in this way, as shown in FIG. 2, after adding the layered clay compound 22 to the solid epoxy resin 21, the softening point of the solid epoxy resin is increased. At temperature, both can be mixed under high shear. Such mixing can be performed using a mixer capable of mixing under high torque (for example, trade name Lab Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.). As a result, the mixture of the epoxy resin and the layered clay compound can be agitated with a very large shearing force, and the silicate layer is peeled between the layers of the layered clay compound by the effect of the shearing force, so that the silicate layer is uniformly in the epoxy resin. Can be dispersed. Moreover, since the molecular weight of the solid epoxy resin is large, the polymer chain of the epoxy resin is entangled with the layered clay compound, and the shearing force at the time of mixing is transmitted to the layered clay compound, causing separation between layers and dispersing. it can. Thus, it becomes possible to disperse | distribute a layered clay compound uniformly in a solid epoxy resin by applying a shearing force. On the other hand, even after adding the layered clay compound to the liquid epoxy resin and mixing using the above-mentioned mixer, the liquid epoxy resin has a lower molecular weight and lower viscosity than the solid epoxy resin, so it is necessary for mixing. No shear force is generated. For this reason, the layered clay compound does not disperse and remains in the resin as an aggregate.

  As described above, the solid epoxy resin becomes a very effective dispersion medium when dispersing the layered clay compound, but is difficult to handle because it is in a solid state at room temperature. In other words, workability is poor. In order to solve this problem, the layered clay compound is uniformly dispersed with a solid epoxy resin, and then mixed with the liquid epoxy resin 23, whereby the layered clay compound is uniformly dispersed and the workability in a liquid state at room temperature. A good epoxy resin composition can be obtained. A desired epoxy resin composition 26 can be obtained by adding an epoxy resin curing agent 24 and a curing accelerator 25 as occasion demands to the epoxy resin mixture in which the delaminated layered clay compound is dispersed and further mixing.

FIG. 3 shows another method for dispersing the layered clay compound in the epoxy resin in a state where the layered layer is peeled off. In this method, an inorganic filler 34 is added as a shearing force imparting material together with the liquid epoxy resin 32 and the layered clay compound 33 to the mixing device 31 provided with the stirrer 311, and the mixture can be stirred and mixed. Since the particle size of the layered clay compound is very small, 50 to 15 nm, it may exist as an aggregate having a size of several μm before being added to the epoxy resin. However, the layered clay compound and a larger amount of the inorganic filler (average particle size 1 to 100 μm) than the layered clay compound are mixed with the epoxy resin, and this is stirred and mixed to form the layered clay compound with the inorganic filler. It is possible to disperse the lamellar clay compound which has been given a shearing force and is an aggregate in the epoxy resin, further delaminate the lamellar clay compound, and uniformly disperse the delaminated silicate layer in the epoxy resin. Examples of such inorganic fillers include silica, alumina, aluminum nitride, boron nitride (BN), boron carbonitride (BCN), aluminum fluoride, magnesium fluoride, calcium fluoride, and the like. These inorganic fillers can be used alone or as a mixture of two or more.

The epoxy resin 32, the layered clay compound 33, and the inorganic filler 34 are sufficiently mixed, and the layered clay compound 33 is delaminated and dispersed in the epoxy resin, and then an organic diluent 35 that does not react with the epoxy resin. To reduce the viscosity of the epoxy resin, transfer to the centrifuge tube 36, and centrifuge. As the organic diluent 35, an organic solvent which can be removed from the epoxy resin under heating or vacuum can be used. For example, methyl ethyl ketone, methanol, ethanol, propanol, isopropanol, dimethylformamide, dimethyl sulfoxide, N-methyl-2 -Pyrrolidone, acetone, acetonitrile and the like can be exemplified. The amount of the organic diluent used is sufficient to reduce the viscosity of the epoxy resin and to cause the inorganic filler 34 to settle smoothly by centrifugation. It can be separated and removed by filtration, vacuum filtration or the like. By this centrifugal separation process, the silicate layer 38 generated by delamination of the layered clay compound remains dispersed in the diluted epoxy resin 37, but the inorganic filler 34 settles. The diluted epoxy resin 37 in which the silicate layer 33 is dispersed can be taken out by decantation. The organic diluent can be removed using vacuum or heating.

  A desired epoxy resin composition can be obtained by adding an epoxy resin curing agent and a curing accelerator depending on the case to the epoxy resin in which the silicate layer thus obtained is dispersed.

  Note that the inorganic filler can be separated and removed by filtration (including vacuum filtration) instead of centrifugation.

By the way, the dispersion state of the layered clay compound can be confirmed by X-ray diffraction measurement. That is, when the epoxy resin composition of the present invention is cured, the layered clay compound is delaminated in a state where no reflection peak is observed within the range of 2θ = 3 to 10 ° in wide angle X-ray diffraction measurement. As described above, the layered clay compound is composed of a silicate layer in which SiO ₄ tetrahedrons are arranged two-dimensionally. When this structure is maintained in the cured product of the epoxy resin composition, a strong reflection peak is observed in the range of 2θ = 3 to 10 ° in the wide-angle X-ray diffraction measurement. The test piece used for the X-ray diffraction measurement was prepared by pouring the epoxy resin composition into a mold and defoaming under vacuum, followed by primary curing at 100 ° C. for 3 hours, and further at 150 ° C. for 15 hours. It can be set as the plate-shaped test piece (length 30mm x width 20mm x thickness 1mm) obtained by making it harden | cure.

  The epoxy resin composition of the present invention can produce a cast insulator by the same production method as in the case of using a normal resin for cast insulators such as injecting it into a mold. The epoxy resin composition of the present invention can provide a cast insulator having high mechanical strength and excellent heat resistance as compared with an epoxy resin used as a conventional cast resin. Such casting insulators include gas switchgear insulation spacers, circuit breaker insulation rods, generator coil impregnation resins, generator turbine end finish varnishes, insulation paints, FRP impregnation resins, power unit insulation seals. Examples thereof include a high thermal conductive insulating sheet for a stopper, a cable coating material, an IC substrate, an interlayer insulating film for LS1 elements, a laminated substrate, a semiconductor sealing material, and a molded insulating component. The epoxy resin composition according to the present invention is not limited to the above-described embodiment, and various materials can be selectively used. In that case, excellent effects can be obtained as well. In recent years, with the downsizing, large capacity, use in high frequency band, high voltage, and severe use environment of electrical / electronic equipment and industrial / heavy electrical equipment, the performance and reliability of cast insulation has been improved. Improvements and stabilization of quality are required. The epoxy resin composition according to the present invention meets these requirements, and can be applied to various electrical / electronic devices and industrial / heavy electrical devices as an epoxy cast insulator.

  EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited by these Examples.

Example 1
A layered clay compound in which quaternary ammonium ions are inserted between layers after preheating 20 parts by weight of bisphenol A type epoxy resin (Ciba Geigy, trade name: CT200) as a solid epoxy resin at 120 ° C. , Trade name: STN) 10 parts by weight was added and mixed for 10 minutes using a universal mixing stirrer (trade name: 5DMV-r type, manufactured by Dalton). Thereafter, this mixture is transferred to a mixer capable of mixing at high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.), at a temperature at which the solid epoxy resin softens (about 50 ° C. in the case of CT200), 30 Mixed for minutes. After completion of mixing in the Laboplast Mill mixer, the mixture was transferred again to the universal mixer, and 80 parts by weight of bisphenol A type epoxy resin (trade name: Epicoat (Ep) 828, manufactured by Japan Epoxy Resin Co., Ltd.), which is a liquid epoxy resin. And mixed for 10 minutes. After mixing, 90 parts by weight of an acid anhydride curing agent for epoxy resin (manufactured by Shin Nippon Rika Co., Ltd., trade name: Ricacid MH-700) and a curing accelerator for epoxy resin (manufactured by NOF Corporation, trade name: M2-100) ) 0.1 part by weight was added and vacuum mixing was performed at 80 ° C. for 10 minutes. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Example 2
The amount of the curing accelerator for epoxy resin used in Example 1 was changed from 0.1 parts by weight to 0.3 parts by weight to prepare test pieces. Specifically, a layered clay in which 20 parts by weight of a bisphenol A type epoxy resin (Ciba Geigy, trade name: CT200), which is a solid epoxy resin, is preheated to 120 ° C. and quaternary ammonium ions are inserted between the layers. 10 parts by weight of a compound (trade name: STN, manufactured by Coop Chemical Co., Ltd.) was added and mixed for 10 minutes using a universal mixing stirrer (trade name: 5DMV-r type, manufactured by Dalton). Thereafter, this mixture is transferred to a mixer capable of mixing at high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.), at a temperature at which the solid epoxy resin softens (about 50 ° C. in the case of CT200), 30 Mixed for minutes. After completion of mixing in the Laboplast Mill mixer, the mixture was transferred again to the universal mixer, and 80 parts by weight of bisphenol A type epoxy resin (trade name: Epicoat (Ep) 828, manufactured by Japan Epoxy Resin Co., Ltd.), which is a liquid epoxy resin. And mixed for 10 minutes. After mixing, 90 parts by weight of an acid anhydride curing agent for epoxy resin (manufactured by Shin Nippon Rika Co., Ltd., trade name: Ricacid MH-700) and a curing accelerator for epoxy resin (manufactured by NOF Corporation, trade name: M2-100) ) 0.3 part by weight was added and vacuum mixing was performed at 80 ° C. for 10 minutes. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Example 3
The amount of the curing accelerator for epoxy resin used in Example 1 was changed from 0.1 parts by weight to 0.5 parts by weight to prepare test pieces. Specifically, a layered clay in which 20 parts by weight of a bisphenol A type epoxy resin (Ciba Geigy, trade name: CT200), which is a solid epoxy resin, is preheated to 120 ° C. and quaternary ammonium ions are inserted between the layers. 10 parts by weight of a compound (trade name: STN, manufactured by Coop Chemical Co., Ltd.) was added and mixed for 10 minutes using a universal mixing stirrer (trade name: 5DMV-r type, manufactured by Dalton). Thereafter, this mixture is transferred to a mixer capable of mixing at high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.), at a temperature at which the solid epoxy resin softens (about 50 ° C. in the case of CT200), 30 Mixed for minutes. After completion of mixing in the Laboplast Mill mixer, the mixture was transferred again to the universal mixer, and 80 parts by weight of bisphenol A type epoxy resin (trade name: Epicoat (Ep) 828, manufactured by Japan Epoxy Resin Co., Ltd.), which is a liquid epoxy resin. And mixed for 10 minutes. After mixing, 90 parts by weight of an acid anhydride curing agent for epoxy resin (manufactured by Shin Nippon Rika Co., Ltd., trade name: Ricacid MH-700) and a curing accelerator for epoxy resin (manufactured by NOF Corporation, trade name: M2-100) ) 0.5 part by weight was added and vacuum mixing was performed at 80 ° C. for 10 minutes. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Example 4
A layered clay compound in which 20 parts by weight of a bisphenol A type epoxy resin (trade name: CT200, manufactured by Ciba Geigy Co., Ltd.), which is a solid epoxy resin, is preheated to 120 ° C., and quaternary ammonium ions are inserted between the layers (Coop Chemical Co., Ltd.) Product name: STN) 10 parts by weight and 0.5 parts by weight of bis (2-ethylhexyl ) sulfosuccinate (trade name: Aerosol OT, manufactured by Wako Pure Chemical Industries, Ltd. ) as a dispersion aid are added and mixed universally It mixed for 10 minutes using the stirrer (The Dalton company make, brand name: 5DMV-r type | mold). Thereafter, this mixture is transferred to a mixer capable of mixing at high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.), at a temperature at which the solid epoxy resin softens (about 50 ° C. in the case of CT200), 30 Mixed for minutes. After completion of mixing in the Laboplast Mill mixer, the mixture was transferred again to the universal mixer, and 80 parts by weight of bisphenol A type epoxy resin (trade name: Epicoat (Ep) 828, manufactured by Japan Epoxy Resin Co., Ltd.), which is a liquid epoxy resin. And mixed for 10 minutes. After mixing, 90 parts by weight of an acid anhydride curing agent for epoxy resin (manufactured by Shin Nippon Rika Co., Ltd., trade name: Ricacid MH-700) and a curing accelerator for epoxy resin (manufactured by NOF Corporation, trade name: M2-100) ) 0.1 part by weight was added and vacuum mixing was performed at 80 ° C. for 10 minutes. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Example 5
A layered clay compound in which 20 parts by weight of a bisphenol A type epoxy resin (trade name: CT200, manufactured by Ciba Geigy Co., Ltd.), which is a solid epoxy resin, is preheated to 120 ° C., and a quaternary ammonium ion having a hydroxyl group is inserted between the layers. 10 parts by weight of Coop Chemical Co., Ltd., trade name: SEN) was added and mixed for 10 minutes using a universal mixing stirrer (trade name: 5DMV-r type, manufactured by Dalton Co.). Thereafter, this mixture is transferred to a mixer capable of mixing at high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.), at a temperature at which the solid epoxy resin softens (about 50 ° C. in the case of CT200), 30 Mixed for minutes. After completion of mixing in the Laboplast Mill mixer, the mixture was transferred again to the universal mixer, and 80 parts by weight of bisphenol A type epoxy resin (trade name: Epicoat (Ep) 828, manufactured by Japan Epoxy Resin Co., Ltd.), which is a liquid epoxy resin. And mixed for 10 minutes. After mixing, 90 parts by weight of an acid anhydride curing agent for epoxy resin (manufactured by Shin Nippon Rika Co., Ltd., trade name: Ricacid MH-700) and a curing accelerator for epoxy resin (manufactured by NOF Corporation, trade name: M2-100) ) 0.1 part by weight was added and vacuum mixing was performed at 80 ° C. for 10 minutes. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Example 6
A test piece was similarly prepared without adding the liquid epoxy resin used in Example 1. Specifically, a layered clay in which 100 parts by weight of a bisphenol A type epoxy resin (Ciba Geigy, trade name: CT200), which is a solid epoxy resin, is preheated to 120 ° C., and then quaternary ammonium ions are inserted between the layers. 6.8 parts by weight of a compound (trade name: STN, manufactured by Corp Chemical Co., Ltd.) was added and mixed for 10 minutes using a universal mixing stirrer (trade name: 5DMV-r type, manufactured by Dalton). Thereafter, this mixture is transferred to a mixer capable of mixing at high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.), at a temperature at which the solid epoxy resin softens (about 50 ° C. in the case of CT200), 30 Mixed for minutes. After completion of mixing in the plastmill mixer, this mixture was transferred again to the universal mixer, and 30 parts by weight of an acid anhydride curing agent for epoxy resin (trade name: HT901, manufactured by Ciba Geigy Co.) was added, and the mixture was heated at 80 ° C. for 10 minutes. Was vacuum mixed. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Comparative Example 1
A test piece was prepared by changing the solid epoxy resin used in Example 1 to a liquid epoxy resin. Specifically, after preheating 100 parts by weight of bisphenol A type epoxy resin (product name: Epicoat (Ep) 828), which is a liquid epoxy resin, to 120 ° C., quaternary ammonium ions are placed between the layers. 10 parts by weight of the inserted layered clay compound (trade name: STN, manufactured by Coop Chemical Co., Ltd.) was added and mixed for 10 minutes using a universal mixing stirrer (trade name: 5DMV-r type, manufactured by Dalton). Then, this mixture was transferred to a mixer capable of mixing with high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and mixed at 50 ° C. for 30 minutes. After completion of mixing in the plastmill mixer, this mixture was transferred again to the universal mixer, and 90 parts by weight of epoxy resin acid anhydride curing agent (made by Shin Nippon Rika Co., Ltd., trade name: Ricacid MH-700) and epoxy resin 0.1 part by weight of a hardening accelerator (manufactured by NOF Corporation, trade name: M2-100) was added, and vacuum mixing was performed at 80 ° C. for 10 minutes. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Comparative Example 2
A test piece was prepared by changing the layered clay compound used in Example 1 from STN to SWN. SWN (trade name: SWN, manufactured by Coop Chemical Co., Ltd.) is a layered clay compound in which sodium ions are present between the layers. Specifically, 20 parts by weight of a bisphenol A type epoxy resin (trade name: CT200, manufactured by Ciba Geigy Co.), which is a solid epoxy resin, is preheated to 120 ° C., and then 10 parts by weight of a layered clay compound SWN in which sodium ions are present between the layers. It added and mixed for 10 minutes using the universal mixing stirrer (The Dalton company make, brand name: 5DMV-r type | mold). Thereafter, this mixture is transferred to a mixer capable of mixing at high torque (trade name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.), at a temperature at which the solid epoxy resin softens (about 50 ° C. in the case of CT200), 30 Mixed for minutes. After completion of mixing in the plastmill mixer, the mixture was transferred again to the universal mixer, and 80 parts by weight of bisphenol A type epoxy resin (trade name: Epicoat (Ep) 828, manufactured by Japan Epoxy Resin Co., Ltd.), which is a liquid epoxy resin, was added. And mixed for 10 minutes. After mixing, 90 parts by weight of an acid anhydride curing agent for epoxy resin (manufactured by Shin Nippon Rika Co., Ltd., trade name: Ricacid MH-700) and a curing accelerator for epoxy resin (manufactured by NOF Corporation, trade name: M2-100) ) 0.1 part by weight was added and vacuum mixing was performed at 80 ° C. for 10 minutes. The mixture was poured into a mold heated to 100 ° C. in advance, defoamed in a vacuum state, and then primary cured at 115 ° C. for 3 hours and then secondary cured at 150 ° C. for 15 hours to prepare each test piece.

Table 1 shows the compositions of the epoxy resin compositions prepared in Examples 1 to 6 and Comparative Examples 1 and 2.

  In Examples 1 to 3 and Example 6, the reactivity was evaluated using the epoxy resin composition before being cured by applying heat. Evaluation of reactivity was performed by measuring the time (gel time) until the resin reaches gelation by heating.

  Examples The epoxy resin compositions (uncured) prepared in Examples 1 to 3 and Example 6 were each taken about 50 mm from the bottom into a glass test tube (diameter 15 mm), and a glass rod (diameter 2 mm) was inserted. Thereafter, the test tube containing the resin was immersed in an oil bath maintained at 130 ° C. and stirred with a glass rod until the resin gelled and solidified. The time from when the test tube was immersed in an oil bath until the resin gelled and solidified and the glass rod stopped moving was measured as the gelation time. In FIG. 4, the gelation time of the epoxy resin composition prepared in Examples 1-3 and Example 6 is shown collectively.

  From FIG. 4, it can be seen that the length of gelation time of the epoxy resin compositions prepared in Examples 1 to 3 is Example 1> Example 2> Example 3. This is due to the difference in the amount of epoxy resin curing accelerator added, and the longer the gelation time is, the greater the amount added. That is, it shows that the reaction rate of the epoxy compound can be controlled by the amount of the curing accelerator for epoxy resin. On the other hand, it can be seen from FIG. 4 that the gelation time of the epoxy resin composition prepared in Example 6 containing no curing accelerator is extremely short. In this system, it can be seen that unless a curing accelerator for epoxy resin is added, it is difficult to control the curing reaction due to the influence of quaternary ammonium ions inserted between layers of the layered clay compound.

  Next, the mechanical properties and heat resistance properties of the test pieces prepared in Examples 1, 4, 5 and Comparative Examples 1 and 2 were evaluated by the methods described below.

  In order to evaluate the mechanical properties of the cured resin, a bending test was performed on each test piece (a strip test piece having a width of 10 mm, a thickness of 3 mm, and a length of 80 mm). The test was conducted according to JIS-K6691 “Thermoplastic Plastics General Test Method (Bending Strength)” using an autograph (trade name: AGS-500A) manufactured by Shimadzu Corporation, with a fulcrum distance of 48 mm and a crosshead moving speed of 2 mm / Minutes, room temperature, and humidity of 35% RH.

  Further, in order to evaluate the heat resistance characteristics of the cured resin, a dynamic viscoelasticity test of each test piece (a strip test piece having a width of 10 mm, a thickness of 3 mm, and a length of 80 mm) was performed. The test uses a dynamic viscoelasticity measuring device (trade name: MDS-110) manufactured by Seiko Instruments Inc., and fixes both ends of the test piece at a distance between supporting points of 20 mm while heating at a heating rate of 2 ° C./min. Then, a sinusoidal load of 1 Hz was applied to the center, and the temperature dependence of the storage elastic modulus was measured from the relationship between the load and strain.

These measurement results are shown in Table 2.

  As is apparent from Table 2, it can be seen that the test pieces prepared according to the examples of the present invention have higher mechanical strength and superior heat resistance than those of the comparative examples.

  When the physical property values of the test pieces prepared in Example 1 and Comparative Example 1 are compared (Table 2), the test piece prepared in Example 1 has a higher bending fracture strength than the test piece prepared in Comparative Example 1. Moreover, it can be seen that the elastic modulus at room temperature is maintained even in a high temperature region. This difference in characteristics is derived from the difference in the dispersion state of the layered clay compound. From the observation of the test piece with a transmission electric microscope (TEM), in the test piece prepared in Example 1, the layered clay compound caused delamination between layers, and each silicate layer forming the layer structure was dispersed in the resin. It was confirmed that Moreover, after pouring the epoxy resin composition prepared in Example 1 into a mold and defoaming under vacuum, it was first cured at 100 ° C. for 3 hours, and further cured secondarily at 150 ° C. for 15 hours. A plate-shaped test piece (length 30 mm × width 20 mm × thickness 1 mm) was prepared, and X-ray diffraction of the plate-shaped test piece was performed using an X-ray diffraction (XRD) measuring device (manufactured by Rigaku Corporation, model: XRD-B). As a result, no reflection peak was observed in the range of 2θ = 3 to 10 ° on the plate-shaped test piece. On the other hand, in the test piece produced in Comparative Example 1, it was confirmed that the layered clay compound was dispersed as an aggregate of several microns. Moreover, the reflection peak was observed in the range of 2 (theta) = 3-10 degrees by the same XRD measurement. For this reason, the agglomerates of the layered clay compound have cracks as the starting point of fracture, so the fracture strength is reduced, and the agglomerates cannot exert an effect as a reinforcing material. The elastic modulus decreased.

Further, comparing the physical property values of the test pieces prepared according to Example 1 and Comparative Example 2, the test piece prepared according to Example 1 has a bending fracture strength of 160 than the test piece prepared according to Comparative Example 2. It can be seen that the value of the elastic modulus at ° C is high. That is, as the layered clay compound, the one in which a quaternary ammonium ion is inserted between the layers like the smectite (STN) used in Example 1 is used as the smectite (SWN) used in Comparative Example 2. It can be seen that it is preferable to use one having sodium ions between layers. Table 3 shows the results of wide-angle X-ray diffraction measurement of these smectites (SWN) and smectites (STN), and the results of visual dispersibility evaluation on bisphenol A type epoxy resin (trade name: CT200, manufactured by Ciba Geigy). The interlayer distance of the layered clay compound can be determined from wide-angle X-ray diffraction measurement. The layered clay compound (STN) has an interlaminar distance longer than that of smectite (SWN) due to the insertion of ammonium ions between the layers, and the atmosphere between the layers becomes oleophilic. It can be seen that the affinity is excellent. For this reason, the smectite (STN) can disperse | distribute uniformly in an epoxy resin, and can provide the outstanding mechanical characteristic and heat resistance.

  Next, when the physical property values of the test pieces prepared according to Example 1 and Example 5 are compared, from Table 2, the test piece prepared according to Example 5 is more bent than the test piece prepared according to Example 1. It can be seen that the strength and the modulus of elasticity at 160 ° C. are high. That is, more excellent mechanical properties and heat resistance can be imparted by using a quaternary ammonium ion having a functional group such as a hydroxyl group as a quaternary ammonium ion present between layers of a layered clay compound. These functional groups have high chemical activity. Moreover, since the glycidyl ring which an epoxy resin has also has very high activity, it becomes possible to cause interaction or a chemical reaction between these functional groups and chemical bonds, and an epoxy resin. For example, the hydroxyl group of the quaternary ammonium ion forms an ether bond by opening the glycidyl ring of the epoxy resin, and an oligomer in which the quaternary ammonium ion and the epoxy resin are linked is generated. The oligomer reacts with the quaternary ammonium ion or the epoxy resin again, thereby forming a three-dimensional network structure in which the molecular chain of the epoxy resin is constrained by the silicate layer of smectite (SEN). As a result, smectite (SEN) serves as a reinforcing material for epoxy resin, exhibits excellent fracture strength in a bending test, and can maintain an elastic modulus comparable to room temperature even in a high temperature region. .

  Comparing the characteristics of the test pieces prepared according to Example 1 and Example 4, the test piece prepared according to Example 4 is higher in bending fracture strength and elastic modulus in the high temperature region than the test piece prepared according to Example 1. It can be seen that it is slightly higher. Bis (2-ethylhexyl sulfosuccinate sodium), which is a kind of surfactant, is added as a dispersion aid to the test piece prepared in Example 4. The surfactant or amphiphilic compound is the surface of the layered clay compound. The absolute value of the zeta potential of the layered clay compound can be increased by adsorbing to the layered clay, and if the absolute value of the zeta potential is large, an electrostatic repulsive force acts between the fine particles, making it difficult to aggregate. The compound can be uniformly dispersed in the epoxy resin.

The schematic diagram which shows the internal structure of the epoxy resin composition which concerns on one embodiment of this invention. The flowchart which shows the process of manufacturing an epoxy resin composition according to one embodiment of this invention. The figure explaining the method for disperse | distributing the layered clay compound in the state which separated into the epoxy resin according to one embodiment of this invention. The figure which shows the gelatinization time of the epoxy resin composition prepared in Examples 1-3 and Example 6. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Molecular chain of epoxy resin, 12 ... Silicate layer of layered clay compound, 21 ... Solid epoxy resin, 23 ... Liquid epoxy resin, 24 ... Curing agent for epoxy resin, 25 ... Curing accelerator, 26 ... Epoxy resin Composition 31. Mixing device 311 Stir bar 32 Liquid epoxy resin 33, 22 Layered clay compound 34 Inorganic filler 36 Centrifuge tube 37 Epoxy resin diluted with organic diluent .

Claims (6)

(A) an epoxy resin containing at least one epoxy resin that is solid at normal temperature and at least one epoxy resin that is liquid at normal temperature, each having two or more epoxy groups per molecule;
(B) a curing agent for epoxy resin, and (c) a layered clay compound having a quaternary ammonium ion between layers, wherein the layered clay compound is mixed in the solid epoxy resin and dispersed in a delaminated state , An epoxy resin composition, characterized in that a solid epoxy resin dispersed in a state where the layered clay compound is mixed and peeled is mixed with the liquid epoxy resin .   The layered clay compound is present in a state where no reflection peak is observed in the range of 2θ = 3 to 10 ° in X-ray diffraction measurement when the epoxy resin composition is cured. 2. The epoxy resin composition according to 1. The epoxy resin composition according to claim 1 or 2 , wherein the time until the epoxy resin is gelled by the epoxy resin curing agent is controlled by addition of an epoxy resin curing accelerator. The epoxy resin composition according to any one of claims 1 to 3 , wherein the layered clay compound is at least one selected from a mineral group consisting of a smectite group, a mica group, and a vermiculite group. The epoxy resin composition according to any one of claims 1 to 4 , wherein aggregation of the dispersed layered clay compound is suppressed by a silane coupling agent. A cast insulator comprising the epoxy resin composition according to any one of claims 1 to 5 .

Images