JP2012233130A - Thermosetting resin composition, and mold coil, switch gear, printed-circuit board, and rotary electric machine using the thermosetting resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting resin composition that reduces the occurrence of stress caused with change of temperature.SOLUTION: The thermosetting resin composition comprises as essential component, a thermosetting resin, a lignin derivative, and an inorganic filler. The mass ratio of the lignin derivative to the thermosetting resin falls in the range of 61 to 110 mass%.

Description

  Embodiments described herein relate generally to a thermosetting resin composition, and a molded coil, a switch gear, a printed board, and a rotating electrical machine using the same.

  For example, a thermosetting resin such as an epoxy resin or an unsaturated polyester resin is used for a molded coil having a coil formed by winding a conductor. Since such a thermosetting resin generally has low thermal conductivity, when the conductor is energized, the temperature of the portion in contact with the conductor increases, while the temperature rise slows as the conductor is separated. To do. For this reason, when the operation is performed such that the temperature of the conductor exceeds the glass transition temperature of the thermosetting resin, the portion of the thermosetting resin that has undergone glass transition and the portion that has not undergone glass transition are formed inside the mold coil. The generation of stress is repeated. Such repeated generation of stress causes, for example, cracks in the thermosetting resin.

JP 2010-100726 A

  The problem to be solved by the present invention is to provide a thermosetting resin composition that reduces the occurrence of stress associated with temperature changes.

  The thermosetting resin composition of the embodiment is a thermosetting resin composition containing a thermosetting resin, a lignin derivative, and an inorganic filler as essential components, and the mass ratio of the lignin derivative to the thermosetting resin. In the range of 61 mass% to 110 mass%.

The figure which shows the structure of the mold coil of one Embodiment typically The figure which shows typically the temperature distribution in the mold coil of one Embodiment The figure which shows typically the manufacturing process of the resin composition of one Embodiment. The figure which shows the relationship between lignin content of the resin composition of one Embodiment, and glass transition temperature difference (DELTA) Tg. It is a figure which shows the relationship between the dynamic viscoelasticity and temperature of the resin composition of one Embodiment, (A) is a figure which shows the glass transition area | region of the resin composition containing a lignin derivative, (B) does not contain a lignin derivative. Diagram showing glass transition region of epoxy resin

Hereinafter, a thermosetting resin composition according to an embodiment of the present invention and a molded coil using the same will be described with reference to FIGS.
As shown in FIG. 1, a molded coil 1 according to an embodiment includes a conductor 2 and a thermosetting resin composition that molds the conductor 2 (hereinafter simply referred to as a resin composition 3). The molded coil 1 is formed in a substantially cylindrical shape or a substantially rectangular tube shape as a whole by casting a coil 4 obtained by winding a conductor 2 in a substantially annular shape or a substantially rectangular shape with a resin composition 3. The mold coil 1 is used with its center hole portion fitted into, for example, a core leg of a transformer or a core of a reactor. The conductor 2 is formed of a conductive material such as copper or aluminum, and an insulating coating is provided on the surface thereof. The conductor 2 may be not only a wire having a circular cross section as shown in FIG. 1 but also a thin plate having a rectangular cross section. Moreover, you may form with electrically conductive materials other than copper and aluminum.

  The resin composition 3 contains an epoxy resin, a lignin derivative, and an inorganic filler as essential components. In this embodiment, bisphenol A type diglyl ether is used as the main material of the epoxy resin. The main material is not limited to bisphenol A type diglyl ether. The lignin derivative is so-called biomass derived from plants, and is extracted by performing high-temperature and high-pressure treatment in the presence of a solvent as will be described later. The inorganic filler is an inorganic material such as so-called silica or alumina, for example, and is added to relieve the difference in linear expansion coefficient between the coil 4 and the resin composition portion when the coil 4 is cast. In the case of this embodiment, the resin composition 3 contains a lignin derivative at a mass ratio of about 80 phr and a reaction accelerator at a rate of 1 phr with respect to 100 phr of epoxy resin (Parts per Hundred epoxy Resin). Moreover, the inorganic filler is contained in an appropriate ratio according to the application. In addition, the resin composition 3 includes additives such as a curing catalyst and a flame retardant within a range that does not hinder the characteristics described later.

  Next, a state that occurs inside the molded coil 1 during operation (energization) will be described. In the molded coil 1, the conductor 2, that is, the coil 4 generates heat during operation. For example, in the case of a molded coil 1 used in a molded transformer (molded transformer) classified as a heat resistant class F in JIS C 4003-1998 “Heat class and heat resistance evaluation of electrical insulation”, the temperature of the conductor 2 during operation is about It becomes 155 ° C. At this time, the temperature of the part which the resin composition 3 contacts the conductor 2 as shown by the point P1 in FIG. On the other hand, the temperature rise is slowed at the part away from the conductor 2 as indicated by the point P2. Specifically, as shown in FIG. 2, the point P1 on the line segment L1 in FIG. 1 rises to about 150 ° C. close to the temperature of the conductor 2, while the point P2 is generally a resin. Since the thermal conductivity of the material is low, the temperature rises only to about 110 ° C. That is, inside the mold coil 1 during operation, as shown in FIG. 2 as a resin layer (region of the resin composition 3), there is a temperature distribution between a portion near the conductor 2 and a separated portion. Has occurred.

  Now, the resin material undergoes a so-called glass transition in which the elastic modulus changes rapidly as the temperature rises. In the case of a general resin material, since the glass transition temperature is around 120 ° C., the glass transition temperature is exceeded at the point P1 shown in FIG. 1, and the glass transition temperature is not reached at the point P2. become. That is, a large temperature distribution is generated in the mold coil 1 so as to straddle the glass transition temperature of the resin material. At this time, depending on the operating condition of the mold coil 1, due to external vibrations or thermal expansion of the resin material itself, the glass transitioned part (the part in a rubbery state) and the part not in the glass transition (the rubbery state). The generation of stress is repeated between the two parts. The generation of such stress is a factor that causes cracks or the like in the thermosetting resin.

  Thus, as a result of repeated research focusing on the composition of the resin material, the inventors have found that the generation of excessive stress can be reduced by adding a lignin derivative to the resin material. Hereinafter, the manufacturing process of the resin composition 3 is demonstrated together with the extraction process of a lignin derivative.

  As shown in FIG. 3, in the lignin derivative extraction step, a suspension step (S1) in which lignocellulose, which is a plant-derived woody material, is added to an aqueous aluminum sulfate solution together with ethanol as a decomposition reaction accelerator. ) Is first implemented. Subsequently, the suspension is stirred while being heated to about several hundred degrees Celsius and pressurized to about several MPa, and a decomposition treatment step (S2) for decomposing lignocellulose is performed. Then, the phase separation process (S3) which adds methyl ethyl ketone which is a solvent, and isolate | separates into an organic phase and an aqueous phase is implemented. In this phase separation step, the lignin derivative extracted from lignocellulose is dissolved in the organic phase, and cellulose and metal oxide are dissolved in the aqueous phase.

  Subsequently, the lignin derivative is extracted through an organic phase recovery step (S4) for recovering only the organic phase solution and a drying step (S5) for drying the organic phase solution. Thereafter, the bisphenol A type diglyl ether, the extracted lignin derivative and the imidazole-based curing catalyst are mixed in a methyl ethyl ketone solvent, and after removing the solvent, the resin composition 3 is manufactured by heat curing. In this case, the lignin derivative functions as a curing agent.

  In the resin composition 3 thus produced, the glass transition temperature difference ΔTg varies depending on the content of the lignin derivative. Here, the glass transition temperature difference ΔTg is a temperature difference between the glass transition start temperature and the glass transition end temperature in the present embodiment. In the case of the present embodiment, the glass transition start temperature is a temperature at which the glass transition (phase transition) starts when the temperature rises, and the glass transition end temperature is the result of the temperature rise resulting in the end of the phase transition. The temperature becomes rubbery. Specifically, as shown in FIG. 4, in the resin composition 3, the glass transition temperature difference ΔTg increases as the content of the lignin derivative increases to about 85 prh, and the content of the lignin derivative is about 85 prh. When the value exceeds V, the glass transition temperature difference ΔTg gradually decreases. The elastic modulus shown in FIG. 4 is the result of measurement by DSC (suggested scanning calorimetry) that measures the transition behavior of the resin in the glass-rubber state based on the heat input and output of the sample.

  Here, the glass transition temperature difference of the epoxy resin single-piece | unit as a comparative example with respect to the resin composition 3 is demonstrated. In the case of an epoxy resin alone, the glass transition temperature difference is generally about 10 ° C., but in the case of an epoxy resin composition containing an inorganic filler such as silica in the epoxy resin, the glass transition temperature difference is about 20 ° C. Degree.

  Therefore, in the resin composition 3, the glass transition temperature difference ΔTg is larger than the glass transition temperature difference (about 20 ° C.) of the epoxy resin composition by adding approximately 25 to 110 phr of the lignin derivative. More than ℃. For this reason, inside the resin composition 3, the temperature range in which a glass state and a rubber state coexist becomes large. Thereby, even if it is a case where a big temperature difference arises locally (for example, between the point P1 and the point P2) from thermal conductivity being low, generation | occurrence | production of stress can be reduced. At this time, when the mold coil 1 applicable to the heat resistance class F is assumed as in this embodiment, the lignin derivative is contained at a rate of 69 to 101 phr, and the glass transition temperature difference ΔTg is set to about 30 ° C. or more. It is preferable. Although this will be described in detail later, even if the temperature at the point P2 shown in FIG. 1 only rises to about 110 ° C. if the glass transition temperature difference ΔTg exceeds about 30 ° C., the point P2 This is because a part of the resin composition 3 can start glass transition.

  Thus, the resin composition 3 which shows the outstanding characteristic that glass transition temperature difference (DELTA) Tg increases by containing a lignin derivative in a thermosetting resin can be obtained. The lignin derivative is mixed with phenols having various molecular weights, and thus has various reactivity. By using this as a curing agent, a thermosetting resin having a gentle glass transition behavior can be produced. . In addition, the resin composition 3 is said to have a higher glass transition temperature (in this embodiment, the middle point between the glass transition start temperature and the glass transition end temperature is the glass transition temperature) than when no lignin derivative is contained. The characteristics are also shown.

  FIG. 5 shows changes in dynamic viscoelasticity of the resin composition 3 measured by DMA (dynamic viscoelasticity measurement) based on the elastic modulus of the sample. As shown in FIG. 5 (A), the resin composition 3 has a glass transition temperature difference ΔTg which is the difference between the glass transition start temperature and the glass transition end temperature, and does not contain the lignin derivative shown in FIG. 5 (B). It increases compared to the glass transition temperature difference ΔTg0 of the material (for example, novolac cured epoxy resin). In addition, in the resin composition 3, the change rate of the dynamic viscoelasticity E ′ is gentler than the change of the dynamic viscoelasticity E′0 of the resin material not including the lignin derivative.

  That is, in the resin composition 3 containing a lignin derivative, the glass transition start temperature decreases while the glass transition end temperature rises compared to the case where no lignin derivative is contained, and the dynamic viscoelasticity change (phase transition) with respect to the temperature change. ) Will be reduced. In the case of the resin composition 3 of the present embodiment, the glass transition temperature difference ΔTg based on the dynamic viscoelasticity E ′ increases to a level exceeding approximately 50 ° C. Therefore, the glass transition region (region from the glass transition start temperature to the glass transition end temperature) of the resin composition 3 is in a state including the maximum temperature or the allowable maximum temperature of the conductor 2 during operation.

  The molded coil 1 is formed by casting the coil 4 with the resin composition 3. The casting of the coil 4 can be performed by a well-known impregnation process or the like, and thus detailed description thereof is omitted. Inside the mold coil 1, the temperature is about 150 ° C. at the point P1 shown in FIG. 1, so that the glass transition is almost completed (see FIG. 5A), and the resin composition 3 is in a rubber state. . And in the point P2 (about 110 degreeC), unlike the case where a general resin material single-piece | unit is used, a part of resin composition 3 starts glass transition (refer FIG. 5 (A)), and a glass state and The rubber state is mixed.

  As a result, a part of the resin composition 3 becomes rubbery at the point P2, and even when linear expansion or a change in elastic modulus occurs at the point P1, the change can be followed at the point P2. It becomes like this. In other words, as the glass transition temperature difference ΔTg increases, the resin composition 3 further increases in the region where the glass state and the rubber state are mixed. Thereby, the stress which generate | occur | produces between the site | part of a glass state and the site | part of a rubber state is relieved. Therefore, even when the coil 4 repeatedly increases and decreases in temperature during operation, by casting the molded coil 1 with the resin composition 3 as in the present embodiment, the temperature changes during operation. Generation | occurrence | production of stress can be reduced and a possibility that a crack etc. may arise inside the resin composition 3 can be suppressed. Accordingly, the reliability of the molded coil 1 can be improved.

(Other embodiments)
In one embodiment, an example of the resin composition 3 containing an epoxy resin as a main material has been shown. However, even in a thermosetting resin containing an unsaturated polyester resin as a main component, generation of stress is reduced by including a lignin derivative. A possible thermosetting resin composition can be obtained.
Moreover, you may use the lignin secondary derivative which introduce | transduced the reactive group as a lignin derivative. When the lignin secondary derivative is used, the crosslinking density is increased by the reactive group. As a result, the elastic modulus of the thermosetting resin composition can be further improved, and the generation of stress due to temperature changes can be further reduced.
In one embodiment, the example in which the resin composition 3 is applied to the mold coil 1 used for the mold transformer classified into the heat resistance class F in JIS C 4003-1998 is shown, but the present invention is not limited to this. For example, the present invention may be applied to a molded coil used in a heat resistant class B molded transformer. Of course, it may be classified according to other standards.

  The resin composition 3 can also be applied to, for example, a switch gear, a printed board, a rotating electric machine, and the like. For example, in the case of a switchgear, the stress can be reduced similarly to the embodiment by using the resin composition 3 as an insulating material. Further, it can be used as a substrate of a printed board or a so-called resist agent. In the case of a rotating electrical machine, it can be used as a varnish for forming a coil end. Furthermore, the resin composition 3 can also be applied to a semiconductor device used in, for example, a power circuit or a power circuit, such as a so-called mold IC. In other words, the resin composition 3 can be used for various applications such as sealing or insulating the conductor 2 whose temperature rises to the vicinity of the glass transition temperature.

  As described above, the thermosetting resin composition (resin composition 3) of the embodiment includes a thermosetting resin, a lignin derivative, and an inorganic filler as essential components, and the lignin derivative is used for the thermosetting resin. It is contained in the range of 61 mass% to 110 mass% in mass ratio. Thereby, the thermosetting resin composition which shows the characteristic of increase of glass transition temperature difference (DELTA) Tg, relaxation of a phase transition, and a raise of glass transition temperature can be obtained.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the drawings, 1 is a molded coil, 3 is a resin composition (thermosetting resin composition), and 4 is a coil.

Claims (9)

A thermosetting resin composition comprising a thermosetting resin, a lignin derivative, and an inorganic filler as essential components,
A thermosetting resin composition comprising the lignin derivative in a mass ratio of 61% by mass to 110% by mass with respect to the thermosetting resin.   2. The thermosetting resin composition according to claim 1, comprising the lignin derivative in a mass ratio of 69% by mass to 101% by mass with respect to the thermosetting resin.   The thermosetting resin composition according to claim 1, wherein the thermosetting resin is an epoxy resin.   The thermosetting resin composition according to claim 1, wherein the thermosetting resin is an unsaturated polyester resin.   The thermosetting resin composition according to any one of claims 1 to 4, wherein the lignin derivative is a lignin secondary derivative into which a reactive group has been introduced.   A molded coil, wherein the coil is cast with the thermosetting resin composition according to any one of claims 1 to 5.   A switchgear comprising the thermosetting resin composition according to any one of claims 1 to 5 as an insulating material.   A printed circuit board comprising the thermosetting resin composition according to any one of claims 1 to 5 as an insulating material.   A rotating electrical machine, wherein a coil end is molded with the thermosetting resin composition according to any one of claims 1 to 5.

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