JP2020079354A - Thermosetting resin composition, motor provided with component made of its cured material, and production method of motor - Google Patents

Abstract

To provide a thermosetting resin composition capable of combining excellent fluidity and mechanical strength of the cured material.SOLUTION: A thermosetting resin composition comprising an unsaturated polyester resin (A), an ethylenic unsaturated compound (B), a glass fiber (C), and an inorganic filler (D), in which a most-frequent value in a fiber length distribution of the glass fiber (C) is 0.8 to 1.1 mm, a difference of L75 and L25 of the glass fiber (C) is 0.4 to 0.7 mm, herein, the L25 and the L75 are, in a number reference fiber length distribution curve obtained by sampling 1000 fibers among 1 g of the glass fiber (C) and by measuring fiber length of the glass fiber (C) with a microscope, fiber lengths when integrated values are 25% and 75%.SELECTED DRAWING: None

Description

  The present disclosure relates to a thermosetting resin composition, a motor including a member made of the cured product, and a method for manufacturing a motor. More specifically, the present disclosure relates to a thermosetting resin composition that can be used for enclosing electric and electronic components such as a motor and a coil, a motor including a member made of the cured product, and a method for manufacturing the motor.

  A thermosetting resin composition obtained by mixing a fiber reinforcement or an inorganic filler with an unsaturated polyester resin has good fluidity and gives a cured product excellent in dimensional accuracy, heat resistance and mechanical strength. It is widely used in the manufacture of equipment, chassis for office equipment, lamp reflectors for automobile headlamps, enclosed motors, etc.

  Among them, in the manufacture of encapsulated motors, electric and electronic components such as coils are encapsulated in the motor, so that the cured product of the thermosetting resin composition is required to have high strength to cope with the internal stress from the encapsulated components. It Therefore, glass fibers are generally blended with the thermosetting resin composition. However, while glass fibers can impart mechanical strength to the thermosetting resin composition, they also cause a decrease in the fluidity of the thermosetting resin composition. If the fluidity of the thermosetting resin composition is low, the encapsulated component may move from the initial position due to the resin pressure during encapsulation, and the encapsulated component may be damaged by the occurrence of disconnection, short circuit, or the like.

  As a means for solving this problem, a method of using glass fibers having a short fiber length (Patent Document 1) is known.

JP 2001-247756 A

  However, when the method using glass fiber having a short fiber length as described in Patent Document 1 is used, there is a drawback that the mechanical strength of the cured product is lowered.

  An object of the present disclosure is to provide a thermosetting resin composition that has both good fluidity and mechanical strength of a cured product.

  As a result of intensive studies to solve the above problems, the present inventors blended glass fibers having a predetermined fiber length distribution in a thermosetting resin composition, and thus had good fluidity. The inventors have found that a thermosetting resin composition having excellent mechanical strength of a cured product can be obtained, and completed the present invention.

That is, the present invention includes the following [1] to [12].
[1]
A thermosetting resin composition comprising an unsaturated polyester resin (A), an ethylenically unsaturated compound (B), a glass fiber (C), and an inorganic filler (D),
The mode in the fiber length distribution of the glass fiber (C) is 0.8 to 1.1 mm,
The difference between L75 and L25 of the glass fiber (C) is 0.4 to 0.7 mm, and each of L25 and L75 is 1000 g from 1 g of the glass fiber (C), and a microscope is used. A thermosetting resin composition having a fiber length at a cumulative value of 25% and 75% in a number-based fiber length distribution curve obtained by measuring the fiber length of the glass fiber (C) using.
[2]
The thermosetting resin composition according to [1], wherein the inorganic filler (D) is at least one selected from calcium carbonate, aluminum oxide, and aluminum hydroxide.
[3]
The thermosetting resin composition according to any one of [1] or [2], wherein the mode in the fiber length distribution of the glass fiber (C) is 0.8 to 1.0 mm.
[4]
The thermosetting resin composition according to any one of [1] to [3], wherein the difference between L75 and L25 of the glass fiber (C) is 0.5 to 0.7 mm.
[5]
Content of the said glass fiber (C) is 20-50 mass parts with respect to a total of 100 mass parts of the said unsaturated polyester resin (A) and the said ethylenically unsaturated compound (B), [1]-[. The thermosetting resin composition according to any one of 4].
[6]
The content of the inorganic filler (D) is 200 to 600 parts by mass based on 100 parts by mass of the total amount of the unsaturated polyester resin (A) and the ethylenically unsaturated compound (B), [1] to The thermosetting resin composition according to any one of [5].
[7]
The content of the ethylenically unsaturated compound (B) is 25 to 70 mass% with respect to the total of the unsaturated polyester resin (A) and the ethylenically unsaturated compound (B), [1] to The thermosetting resin composition according to any one of [6].
[8]
The thermosetting resin composition according to any one of [1] to [7], which further contains a low shrinkage agent (E).
[9]
The thermosetting resin composition according to any one of [1] to [8], which further contains a curing agent (F).
[10]
The thermosetting resin composition according to any one of [1] to [9], which further contains a release agent (G).
[11]
A motor comprising a member made of a cured product of the thermosetting resin composition according to any one of [1] to [10].
[12]
Encapsulating the thermosetting resin composition according to any one of [1] to [10] in a housing having an electric/electronic component therein, and heating and curing the thermosetting resin composition. Motor manufacturing method.

  According to the present disclosure, it is possible to provide a thermosetting resin composition having both good fluidity and mechanical strength of a cured product.

  Hereinafter, the thermosetting resin composition of the present disclosure will be described in detail. The present invention is not limited to the embodiments described below.

  In the following description, the “ethylenically unsaturated bond” means a double bond formed between carbon atoms excluding carbon atoms forming an aromatic ring.

  The "median diameter" means a particle diameter that is 50% cumulative in the volume-based particle diameter distribution obtained by the laser diffraction/scattering method.

  “(Meth)acrylate” means acrylate or methacrylate, and “(meth)acrylic” means acrylic or methacrylic.

<1. Thermosetting resin composition>
The thermosetting resin composition of one embodiment contains an unsaturated polyester resin (A), an ethylenically unsaturated compound (B), a glass fiber (C), and an inorganic filler (D).

[Unsaturated polyester resin (A)]
The unsaturated polyester resin is obtained by polycondensing a polyhydric alcohol, an unsaturated polybasic acid, and optionally a saturated polybasic acid, and is not particularly limited. The unsaturated polybasic acid is a polybasic acid having an ethylenically unsaturated bond, and the saturated polybasic acid is a polybasic acid having no ethylenically unsaturated bond. The unsaturated polyester resin may be only one kind or two or more kinds.

  Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, pentanediol, hexanediol, neopentanediol, hydrogenated bisphenol A, bisphenol A, and glycerin. . Among these, propylene glycol, neopentanediol, hydrogenated bisphenol A and bisphenol A are preferable, and propylene glycol is more preferable, from the viewpoints of heat resistance of the cured product, mechanical strength and resin fluidity during molding. The polyhydric alcohols may be used alone or in combination of two or more.

  Examples of unsaturated polybasic acids include maleic acid, maleic anhydride, fumaric acid, citraconic acid, itaconic acid and the like. Among these, maleic anhydride and fumaric acid are more preferable from the viewpoints of heat resistance of the cured product, mechanical strength, resin fluidity during molding, and the like. The unsaturated polybasic acids may be used alone or in combination of two or more.

  Examples of the saturated polybasic acid include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, endomethylenetetrahydrophthalic anhydride and the like. Can be mentioned. Among these, phthalic anhydride and isophthalic acid are more preferable from the viewpoints of heat resistance, mechanical strength, resin fluidity during molding, and the like. The saturated polybasic acids may be used alone or in combination of two or more.

  The unsaturated polyester resin can be synthesized by a known method using the above raw materials. Various conditions in the synthesis of the unsaturated polyester resin can be appropriately set according to the raw material used and the amount thereof, but generally, at a temperature of 140 to 230° C. in an inert gas stream such as nitrogen gas. An esterification reaction under pressure or reduced pressure can be used. In the esterification reaction, an esterification catalyst can be used if necessary. Examples of esterification catalysts include known catalysts such as manganese acetate, dibutyltin oxide, stannous oxalate, zinc acetate, and cobalt acetate. The esterification catalyst may be used alone or in combination of two or more kinds.

  The weight average molecular weight (Mw) of the unsaturated polyester resin is not particularly limited. The weight average molecular weight of the unsaturated polyester resin is preferably 3,000 to 25,000, more preferably 5,000 to 20,000, and further preferably 7,000 to 18,000. When the weight average molecular weight is 3,000 to 25,000, the moldability of the thermosetting resin composition is further improved. In the present disclosure, the “weight average molecular weight” is a standard polystyrene conversion value measured by size exclusion chromatography (SEC), for example, gel permeation chromatography (GPC).

The unsaturated degree of the unsaturated polyester resin is preferably 50 to 100 mol %, more preferably 60 to 100 mol %, and further preferably 70 to 100 mol %. When the degree of unsaturation is in the above range, the moldability of the thermosetting resin composition is better. The degree of unsaturation of the unsaturated polyester resin can be calculated by the following formula using the unsaturated polybasic acid used as a raw material and the number of moles of the saturated polybasic acid.
Unsaturation degree (mol %)={(moles of unsaturated polybasic acid)/(moles of unsaturated polybasic acid+moles of saturated polybasic acid)}×100

[Ethylenically unsaturated compound (B)]
The ethylenically unsaturated compound can be used without particular limitation as long as it has an ethylenically unsaturated bond copolymerizable with the unsaturated polyester resin. Examples of the ethylenically unsaturated compound include aromatic monomers such as styrene, vinyltoluene, α-methylstyrene, and divinylbenzene; 2-hydroxyethyl methacrylate, polyalkylene oxide diacrylate, triethylene glycol di(meth)acrylate. , (Meth)acrylate monomers such as tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate; diallyl phthalate, triallyl isocyanurate, diallyl phthalate Examples thereof include monomers having an alkenyl group such as prepolymers; and oligomers in which a plurality of the above monomers are bonded. Among these, styrene and methyl methacrylate are preferable, and styrene is particularly preferable, from the viewpoint of reactivity with the unsaturated polyester resin. The ethylenically unsaturated compound may be used alone or in combination of two or more kinds.

  The content of the ethylenically unsaturated compound is preferably 25% by mass or more based on the total amount of the unsaturated polyester resin and the ethylenically unsaturated compound. This allows the thermosetting resin composition to have a viscosity that makes it easy to handle. From this viewpoint, the content of the ethylenically unsaturated compound is more preferably 27% by mass or more, further preferably 30% by mass or more.

  The content of the ethylenically unsaturated compound is preferably 70% by mass or less based on the total amount of the unsaturated polyester resin and the ethylenically unsaturated compound. Thereby, the mechanical strength of the cured product of the thermosetting resin composition can be increased. From this viewpoint, the content of the ethylenically unsaturated compound is more preferably 68% by mass or less, further preferably 65% by mass or less.

[Glass fiber (C)]
Glass fibers are fibrous substances having an aspect ratio of 3 or more. The aspect ratio can be measured by the microscope method described in JIS Z 8900-1:2008 “Particles for measuring particle diameter measuring device”. Examples of the glass fiber include chopped strand glass. The mode in the fiber length distribution of the glass fiber is 0.8 to 1.1 mm, and the difference between L75 and L25 is 0.4 to 0.7 mm. L25 and L75 each have a cumulative value in a number-based fiber length distribution curve in increments of 0.05 mm obtained by collecting 1000 fibers from 1 g of glass fiber and measuring the fiber length of the glass fiber using a microscope. Fiber lengths at 25% and 75%. The mode value is the fiber length with the highest fraction in the number-based fiber length distribution curve obtained in the same manner in 0.05 mm increments.

  The most frequent value in the fiber length distribution of the glass fiber is 0.8 to 1.1 mm, preferably 0.8 to 1.0 mm, and more preferably 0.8 to 0.9 mm. If the mode value in the fiber length distribution is 0.8 mm or more, the cured product has good mechanical strength, and if it is 1.1 mm or less, the fluidity is good.

  The difference between L75 and L25 of the glass fiber is 0.4 to 0.7 mm, preferably 0.5 to 0.7 mm, and more preferably 0.6 to 0.7 mm. The difference between L75 and L25 indicates the size (width) of the glass fiber length distribution. When the difference between L75 and L25 is large in the glass fibers having the same mode value, the ratio of long fibers to the whole is large, so that the fluidity is lowered. When the difference between L75 and L25 is 0.7 mm or less, it is possible to suppress deterioration of fluidity due to the presence of long fibers. On the other hand, in the case of glass fibers having the same mode value, when the difference between L75 and L25 is small, the ratio of long fibers to the whole is small, and therefore the decrease in fluidity due to the presence of long fibers is not a problem. However, since the number of glass fibers per unit mass increases as compared with the case where the difference between L75 and L25 is large, it is considered that the fluidity also decreases when the difference between L75 and L25 is too small. When the difference between L75 and L25 is 0.4 mm or more, it is possible to suppress the decrease in fluidity due to such an increase in the number of glass fibers.

  The glass fiber content is preferably 20 to 50 parts by mass, more preferably 25 to 45 parts by mass, and even more preferably 100 parts by mass of the unsaturated polyester resin and the ethylenically unsaturated compound. Is 30 to 40 parts by mass. When the compounding amount of the glass fiber is 20 parts by mass or more, the mechanical properties of the molded product are better. On the other hand, when the compounding amount of the glass fibers is 50 parts by mass or less, the glass fibers are more uniformly dispersed in the thermosetting resin composition, and a homogeneous molded product can be manufactured.

[Inorganic filler (D)]
As the inorganic filler, those known in the technical field of the present invention can be used. As the inorganic filler, for example, calcium carbonate, silica, aluminum oxide, aluminum hydroxide, barium sulfate, calcium sulfate, calcium hydroxide, calcium oxide, magnesium oxide, magnesium hydroxide, wollastonite, clay, kaolin, mica, Examples include gypsum, silicic acid anhydride, and glass powder. Among these, calcium carbonate, aluminum oxide and aluminum hydroxide are preferable because they are inexpensive. The inorganic fillers may be used alone or in combination of two or more.

  The median diameter of the inorganic filler is preferably 1 to 100 μm, more preferably 1 to 60 μm, and further preferably 1 to 50 μm from the viewpoint of the viscosity of the thermosetting resin composition during molding. preferable. When the median diameter of the inorganic filler is 1 μm or more, the aggregation of particles can be suppressed. On the other hand, when the median diameter of the inorganic filler is 100 μm or less, the moldability of the thermosetting resin composition is good.

  The shape of the inorganic filler is not particularly limited. Examples of the shape of the inorganic filler include substantially spherical, ellipsoidal, scaly, and amorphous shapes.

  The blending amount of the inorganic filler is preferably 200 to 600 parts by mass, and more preferably 300 to 500 parts by mass with respect to 100 parts by mass of the total amount of the unsaturated polyester resin and the ethylenically unsaturated compound. When the compounding amount of the inorganic filler is 200 parts by mass or more, the cured product has better mechanical properties. When the compounding amount of the inorganic filler is 600 parts by mass or less, the inorganic filler is more uniformly dispersed in the thermosetting resin composition, and a homogeneous molded body can be manufactured.

[Low shrinking agent (E)]
A low shrinkage agent may be added to the thermosetting resin composition. The low-contraction agent is not particularly limited, and those known in the technical field of the present invention can be used. Of these, thermoplastic resins are preferred. Examples of the low-shrinking agent include polystyrene, polyethylene, polymethylmethacrylate, polyvinyl acetate, saturated polyester, polycaprolactone, and styrene-butadiene rubber. The low-contraction agent may be used alone or in combination of two or more kinds.

  The compounding amount of the low-shrinking agent is preferably 20 to 40 parts by mass based on 100 parts by mass of the total amount of the unsaturated polyester resin and the ethylenically unsaturated compound. When the compounding amount of the low-shrinking agent is 20 parts by mass or more, the shrinkage rate of the cured product becomes small, and desired dimensional accuracy can be obtained in the molded product. On the other hand, when the compounding amount of the low-shrinking agent is 40 parts by mass or less, the cured product has better mechanical properties.

[Curing agent (F)]
A curing agent may be added to the thermosetting resin composition. The curing agent is not particularly limited as long as it is a radical initiator capable of polymerizing an ethylenically unsaturated bond, and those known in the technical field of the present invention can be used. Examples of the curing agent include peroxides such as diacyl peroxide, peroxy ester, hydroperoxide, dialkyl peroxide, ketone peroxide, peroxyketal, alkyl perester, and percarbonate. Among these peroxides, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylperoxide Oxyisopropyl carbonate, t-butyl peroxybenzoate, dicumyl peroxide, and di-t-butyl peroxide are preferred. The curing agents may be used alone or in combination of two or more.

  The compounding amount of the curing agent is preferably 1 to 10 parts by mass, and more preferably 1 to 5 parts by mass with respect to 100 parts by mass as the total of the unsaturated polyester resin and the ethylenically unsaturated compound. When the compounding amount of the curing agent is 1 part by mass or more, the curing reaction during molding occurs uniformly, and the physical properties and appearance of the cured product become good. On the other hand, when the compounding amount of the curing agent is 10 parts by mass or less, the storage stability of the thermosetting resin composition becomes good and the handleability is improved.

[Release agent (G)]
A release agent may be added to the thermosetting resin composition. The release agent is not particularly limited, and those known in the technical field of the present invention can be used. Examples of the release agent include stearic acid, oleic acid, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, stearic acid amide, oleic acid amide, silicone oil, and synthetic wax. The release agent may be used alone or in combination of two or more kinds.

  The compounding amount of the release agent is preferably 5 to 20 parts by mass with respect to 100 parts by mass in total of the unsaturated polyester resin and the ethylenically unsaturated compound. When the compounding amount of the release agent is 5 parts by mass or more, the mold release property of the cured product at the time of molding is good and the product productivity is good. On the other hand, when the compounding amount of the release agent is 20 parts by mass or less, a cured product having a good appearance can be obtained without excessive release agent contaminating the surface of the cured product.

[Other additives]
The thermosetting resin composition, in addition to the above components, components known in the technical field of the present invention such as a thickener, a colorant, a polymerization inhibitor, and a thinning agent, within the range that does not impair the effects of the present invention. Can be included in.

  The thickener is a compound other than the inorganic filler (D) that exhibits a thickening effect, and examples thereof include an isocyanate compound. The thickeners may be used alone or in combination of two or more. The addition amount of the thickener can be appropriately adjusted depending on the handling property, fluidity and the like required for the thermosetting resin composition.

  The colorant is used when coloring the cured product. As the colorant, various inorganic pigments or organic pigments can be used. The colorants may be used alone or in combination of two or more. The amount of the colorant added can be appropriately adjusted depending on the degree of coloring desired for the cured product.

  Examples of the polymerization inhibitor include hydroquinone, trimethylhydroquinone, p-benzoquinone, naphthoquinone, t-butylhydroquinone, catechol, pt-butylcatechol, 2,6-di-t-butyl-4-methylphenol and the like. Be done. The polymerization inhibitor may be used alone or in combination of two or more kinds. The addition amount of the polymerization inhibitor can be appropriately adjusted according to the storage environment and period of the curable resin composition, curing conditions and the like.

<2. Method for producing thermosetting resin composition>
The thermosetting resin composition is an unsaturated polyester resin (A), an ethylenically unsaturated compound (B), a glass fiber (C), an inorganic filler (D) and, if necessary, an optional component. It can be produced by mixing a low shrinkage agent (E), a curing agent (F), a release agent (G), an additive, or a combination of two or more kinds thereof. Examples of the mixing method include kneading. The kneading method is not particularly limited, and for example, a kneader, a disper, a planetary mixer or the like can be used. The kneading temperature is preferably 5°C to 40°C, more preferably 10 to 30°C.

  There is no particular limitation on the order of mixing the components when producing the thermosetting resin composition. For example, when the unsaturated polyester resin and a part or all of the ethylenically unsaturated compound are mixed and then the other components are mixed, the thermosetting resin composition in which the respective components are sufficiently dispersed or uniformly mixed is obtained. It is preferable because it is easily obtained. At least a part of the ethylenically unsaturated compound may be premixed with the unsaturated polyester resin that acts as a solvent, a dispersion medium, or the like.

  Examples of the method for mixing the glass fibers include a method in which glass fibers having a predetermined fiber length distribution are prepared in advance, and the glass fibers are mixed with a composition containing each component other than the glass fibers. According to this method, the fiber length distribution of the glass fiber can be finely adjusted. Another method is to mix the glass fibers with the thermosetting resin composition and then knead the glass fibers to break them to achieve a predetermined fiber length distribution. The fiber length distribution of the glass fiber can be controlled by conditions such as the type and amount of other components to be kneaded, the type of stirrer, the stirring speed, the stirring temperature, the stirring time and the like. This method does not require breakage of the glass fiber in advance, so the process is simple.

<3. Curing Method of Thermosetting Resin Composition>
By molding the thermosetting resin composition into a desired shape and curing it, a molded article containing a cured product of the thermosetting resin composition can be produced. The molding and curing method is not particularly limited, and a method commonly used in the technical field of the present invention, for example, compression molding, transfer molding, injection molding or the like can be used.

  The molding and curing steps of the thermosetting resin composition are not particularly limited, but are represented by, for example, a method of opening the mold and pouring the resin composition into the mold, depressurizing the inside of the mold, or injection molding. There is a method of injecting the resin composition from the outside into the closed mold through a hole provided in the mold such as a spool by applying pressure from the outside of the mold. The conditions for curing the thermosetting resin composition in the mold can be appropriately set depending on the material to be used, and an example of preferable conditions is a temperature of 120 to 180° C. and a curing time of 1 to 30 minutes.

  In one embodiment, a motor including a cured product of a thermosetting resin composition is provided. The motor can be manufactured by, for example, a method including encapsulating the thermosetting resin composition in a housing having an electric/electronic component inside and heating and curing the thermosetting resin composition.

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these.

<1. Ingredient>
Glass fiber (C): Chopped strand glass (manufactured by Nitto Boseki Co., Ltd.) 3 mm or 1 mm
Inorganic filler (D): calcium carbonate (median diameter 20 μm)
Low shrinkage agent (E): polystyrene Curing agent (F): t-butylperoxy-2-ethylhexanoate Release agent (G): calcium stearate

<2. Synthesis of unsaturated polyester resin (A)>
In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser, 0.93 kg (9.5 mol) of maleic anhydride and 0.07 kg (0.5 mol) of phthalic anhydride were added. , Propylene glycol 0.76 kg (10 mol) were charged. Then, while heating and stirring under a nitrogen gas stream, the temperature was raised to 200° C. to carry out an esterification reaction to obtain an unsaturated polyester resin A-1. Thereafter, the styrene monomer was added so as to be 30% by mass based on the total amount of the unsaturated polyester resin A-1 and the styrene monomer. The unsaturated polyester resin A-1 obtained had an unsaturation degree of 95 mol% and a weight average molecular weight of 8,000.
The weight average molecular weight was measured at room temperature (23° C.) under the following conditions using gel permeation chromatography (GPC), and was determined using a standard polystyrene calibration curve.
Device: Showex (registered trademark) GPC-101 manufactured by Showa Denko KK
Column: Showa Denko LF-804
Column temperature: 40°C
Sample: 0.2 mass% tetrahydrofuran solution of unsaturated polyester resin Flow rate: 1 mL/min Eluent: Tetrahydrofuran Detector: RI-71S

<3. Preparation of Thermosetting Resin Composition>
Example 1, Comparative Examples 1 to 3
Components having the composition shown in Table 1 except glass fiber were put into a double-arm kneader and kneaded for 30 minutes. Then, glass fibers were added and kneaded for the time shown in Table 1 to obtain thermosetting resin compositions of Example 1 and Comparative Examples 1 to 3. After dissolving the thermosetting resin composition in acetone, it is filtered, 1000 chopped strands are collected from 1 g of the glass fiber remaining on the filter paper, and measured with a microscope to measure the glass fiber length distribution. The mode values, L25 and L75, were calculated.

<4. Evaluation method of thermosetting resin composition>
Various physical properties of the thermosetting resin compositions and molded products obtained in Example 1 and Comparative Examples 1 to 3 were evaluated by the following test methods. The results of these evaluations are shown in Table 1.

(1) Flowability The flow length (spiral flow value) was measured by a spiral flow test. Specifically, a semicircular spiral flow mold having a cross section of φ3 mm was attached to a 70 t transfer molding machine, and a thermosetting resin composition was prepared under the conditions of a raw material charge amount of 50 g, a molding temperature of 150° C. and a molding pressure of 10 MPa. The spiral flow value of was measured.

(2) Moldability The thermosetting resin composition is molded under the following conditions and visually observed, and the unfilled portion of the molded product and the one without unevenness of appearance are “good”, the unfilled portion of the molded product or Those with non-uniform appearance were designated as "poor".
Molding machine: 150-ton compression molding machine (Osaka Jack Manufacturing Co., Ltd.)
Molding die: 320 x 220 mm flat plate molding die Molding temperature: 160°C up and down
Molding pressure: 80 kgf/cm ²
Pressurization time: 300 seconds Sample amount: 400g

(3) Bending strength A thermosetting resin composition is compression-molded (a compression molding machine manufactured by Techno Marshichi Co., Ltd.) under the conditions of a molding temperature of 160° C., a molding pressure of 10 MPa, and a molding time of 3 minutes to perform a flexural modulus test. A piece (length 90 mm×width 10 mm×height 4 mm) was prepared and the bending strength was measured according to JIS K6911:1995 5.17.

  From Table 1, the bending strength of Example 1 in which the mode value is in the range of 0.8 to 1.1 mm, and the arrangement comparative examples 1 and 3 is better than that of Comparative Example 2 in which the mode value is 0.7 mm. Met. However, Example 1 in which the difference between L75 and L25 is in the range of 0.4 to 0.7 mm has a larger spiral flow than Comparative Examples 1 to 3, and the fluidity of the composition in addition to the mechanical strength of the cured product. It is clear that it is also excellent.

Claims (12)

A thermosetting resin composition comprising an unsaturated polyester resin (A), an ethylenically unsaturated compound (B), a glass fiber (C), and an inorganic filler (D),
The mode in the fiber length distribution of the glass fiber (C) is 0.8 to 1.1 mm,
The difference between L75 and L25 of the glass fiber (C) is 0.4 to 0.7 mm, and each of L25 and L75 is 1000 g from 1 g of the glass fiber (C), and a microscope is used. A thermosetting resin composition having a fiber length at a cumulative value of 25% and 75% in a number-based fiber length distribution curve obtained by measuring the fiber length of the glass fiber (C) using.   The thermosetting resin composition according to claim 1, wherein the inorganic filler (D) is at least one selected from calcium carbonate, aluminum oxide, and aluminum hydroxide.   The thermosetting resin composition according to claim 1 or 2, wherein the mode in the fiber length distribution of the glass fiber (C) is 0.8 to 1.0 mm.   The thermosetting resin composition according to any one of claims 1 to 3, wherein a difference between L75 and L25 of the glass fiber (C) is 0.5 to 0.7 mm.   Content of the said glass fiber (C) is 20-50 mass parts with respect to a total of 100 mass parts of the said unsaturated polyester resin (A) and the said ethylenically unsaturated compound (B), 1-4. The thermosetting resin composition according to any one of 1.   Content of the said inorganic filler (D) is 200-600 mass parts with respect to a total of 100 mass parts of the said unsaturated polyester resin (A) and the said ethylenically unsaturated compound (B). The thermosetting resin composition according to any one of 5 above.   Content of the said ethylenically unsaturated compound (B) is 25-70 mass% with respect to the total of the said unsaturated polyester resin (A) and the said ethylenically unsaturated compound (B). The thermosetting resin composition according to any one of 6 above.   The thermosetting resin composition according to any one of claims 1 to 7, further comprising a low shrinkage agent (E).   The thermosetting resin composition according to claim 1, further comprising a curing agent (F).   The thermosetting resin composition according to any one of claims 1 to 9, further comprising a release agent (G).   A motor comprising a member made of a cured product of the thermosetting resin composition according to claim 1.   Encapsulating the thermosetting resin composition according to any one of claims 1 to 10 in a housing having an electric/electronic component therein, and heating and curing the thermosetting resin composition. Motor manufacturing method.