Manufacturing method for molded products

Abstract

The present invention provides a method for manufacturing a molded article that can produce a molded article with reduced burrs and voids. [Solution] A method for manufacturing a molded article, comprising injecting a thermosetting resin composition from the injection section of a mold into a cavity, while exhausting the gas in the cavity through an air vent, and then heating and curing the composition, wherein the temperature of the mold when injecting the thermosetting resin composition is T°C, the spiral flow value of the thermosetting resin composition at T+10°C is 80 to 120 cm, and the thickness of the air vent is 15 to 55 μm.

Description

Technical Field

[0001] The content of this disclosure relates to a method for manufacturing a molded body.

Background Art

[0002] In motors, transformers, and the like for household electrical appliances, there is an increasing demand for miniaturization, thinning, weight reduction, and high output of products. In addition, due to the characteristics of the usage environment of such devices, they are required to be low-noise and low-vibration. To meet this requirement, a structure has been proposed in which an electromagnetic coil wound around a stator core is covered with a mold resin (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a method of molding the stator so as to be covered with a mold resin, there is a method of injecting a thermosetting resin composition into a mold in which the stator is installed and heating and curing it. Conventionally, in this method, an excessive amount of the thermosetting resin composition is injected into the mold cavity, and the excess thermosetting resin composition is overflowed to suppress molding defects such as voids and chips due to filling failure. Therefore, the molded body obtained by this method has a product outer part, that is, a burr. Therefore, a process for removing the burr was necessary. Furthermore, since an excessive amount of the thermosetting resin composition is used for the product, it is not desirable in terms of cost.

[0005] This disclosure provides a method for manufacturing a molded body that can obtain a molded product with reduced burrs and voids.

Means for Solving the Problems

[0006] The contents of this disclosure include the following aspects: [1] A method for manufacturing a molded article, comprising injecting a thermosetting resin composition from the injection section of a mold into a cavity, while exhausting the gas in the cavity through an air vent, and then heating and curing the composition, The temperature of the mold when injecting the thermosetting resin composition is T°C, and the spiral flow value of the thermosetting resin composition at T+10°C is 80-120 cm. A method for manufacturing a molded article, wherein the thickness of the air vent is 15 to 55 μm. [2] The thermosetting resin composition is (B) thermosetting resin, (C) Ethylene unsaturated monomers, (D) Thermal polymerization initiator, (E) Glass fiber, and (F) Inorganic filler A method for producing a molded article according to [1], which contains [1]. [3] The method for producing a molded article according to [2], wherein the thermosetting resin composition contains (G) a thickening agent. [4] A method for manufacturing a molded article according to [2] or [3], wherein the (E) glass fiber is chopped strand glass. [5] A method for manufacturing a molded article according to any one of [2] to [4], wherein the fiber length of the glass fiber (E) is 6 mm or less. [6] The total amount of the (B) thermosetting resin and the (C) ethylenically unsaturated monomer is 100 parts by mass. (E) Glass fiber in 10 to 70 parts by mass, and The inorganic filler (F) is divided into 150 to 600 parts by mass. A method for producing a molded article according to any one of [2] to [5], which contains [2]. [7] A method for producing a molded article according to any one of [2] to [6], wherein the average particle size of the inorganic filler (F) is 0.1 to 100 μm. [8] A method for manufacturing a molded article according to any one of [1] to [7], wherein the width of the air vent is 5 to 15 mm. [9] A method for manufacturing a molded article according to any one of [1] to [8], wherein the injection is performed with the electronic components placed in the cavity.

[10] A method for manufacturing a molded article according to any one of [1] to [9], wherein the mold is a combination of two or more molds, and the injection section and the air vent are provided in separate molds.

[11] The method for manufacturing a molded article according to [9], wherein the electronic component is at least one selected from a stator and a rotor.

[12] A method for manufacturing a molded article according to any one of [1] to

[11] , wherein the mold is installed in a vertical molding machine.

[13] A method for producing a molded article according to any one of [2] to

[12] , wherein the thermosetting resin composition contains (A) a saturated polyester resin.

[14] The (B) thermosetting resin contains at least (B-1-1) unsaturated polyester resin, The (B-1-1) unsaturated polyester resin is a polycondensate of a diol and an unsaturated polybasic acid. A method for producing a molded article according to any one of [2] to

[13] , wherein the (B-1-1) unsaturated polyester resin contains a structure derived from propylene glycol and a structure derived from neopentyl glycol.

[15] The thermosetting resin composition contains (A) a saturated polyester resin, The thermosetting resin composition comprises 100 parts by mass of the total amount of the (B) thermosetting resin and the (C) ethylenically unsaturated monomer. The saturated polyester resin (A) is divided into 5 to 30 parts by mass. The (B) thermosetting resin is 20 to 80 parts by mass, The above (C) ethylenically unsaturated monomer is 80 to 20 parts by mass, The (D) thermal polymerization initiator is 0.5 to 20 parts by mass. 10 to 70 parts by mass of the (E) glass fiber, 150 to 600 parts by mass of the (F) inorganic filler, and 0.2 to 9 parts by mass of the (G) thickener The manufacturing method of the molded body according to any one of [2] to

[14] , containing them.

Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a manufacturing method of a molded body capable of obtaining a molded product with reduced burrs and voids.

Brief Description of the Drawings

[0008] [Figure 1A] It is a schematic diagram of an exemplary mold. [Figure 1B] It is a diagram showing the positional relationship between the injection part and the air vent when the mold of FIG. 1A is viewed from directly above. [Figure 2A] It is a schematic diagram of an exemplary mold. [Figure 2B] It is a diagram showing the positional relationship between the injection part and the air vent when the mold of FIG. 2A is viewed from directly above. [Figure 3A] It is a schematic diagram of an exemplary mold. [Figure 3B] It is a diagram showing the positional relationship between the injection part and the air vent when the mold of FIG. 3A is viewed from directly above. [Figure 4A] It is a schematic diagram of an exemplary mold. [Figure 4B] It is a diagram showing the positional relationship between the injection part and the air vent when the mold of FIG. 4A is viewed from directly above. [Figure 5A] It is a schematic diagram of an exemplary mold. [Figure 5B] It is a diagram showing the positional relationship between the injection part, the air vent, and the resin pool when the mold of FIG. 5A is viewed from directly above. [Figure 6A] It is a schematic overall view and a partial cross-sectional view of an exemplary mold. [Figure 6B] It is a diagram showing the positional relationship between the injection part and the air vent when the mold of FIG. 6A is viewed from directly above.

Mode for Carrying Out the Invention

[0009] The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments shown below.

[0010] In this specification, when "~" is used for a numerical range, the numbers at both ends are the upper and lower limits, respectively, and are included in the numerical range. If multiple upper or lower limits are listed, a numerical range can be created from all combinations of upper and lower limits. Similarly, if multiple numerical ranges are listed, separate numerical ranges can be created by individually selecting and combining upper and lower limits from those ranges.

[0011] In this specification, "(meth)acrylic acid" means methacrylic acid or acrylic acid, "(meth)acrylate" means acrylate or methacrylate, and "(meth)acryloyloxy" means acryloyloxy or methacryloyloxy.

[0012] In this specification, "thermosetting resin" refers to a resin that hardens by forming a cross-linked structure when heated, and indicates the state before hardening.

[0013] In this specification, "ethylenically unsaturated bond" means a double bond formed between carbon atoms excluding the carbon atoms that form the aromatic ring, and "ethylenically unsaturated monomer" means a monomer having an ethylenically unsaturated bond.

[0014] In this specification, "weight-average molecular weight" and "number-average molecular weight" are defined as values ​​obtained by measuring at room temperature (23°C) under the following conditions using gel permeation chromatography (GPC) and using a standard polystyrene calibration curve. Device: Shodex (trademark) GPC-101 (Resonac Co., Ltd.) Column: Shodex (trademark) LF-804 (Resonac Co., Ltd.) Column temperature: 40℃ Sample: 0.2% by mass of the sample in a tetrahydrofuran solution. Flow rate: 1mL / min Eluent: Tetrahydrofuran Detector: Shodex® RI-71S (Resonac Corporation)

[0015] In this specification, "acid value" refers to the acid value measured in accordance with JIS K6901:2021 5.3. That is, the acid value means the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 g of non-volatile matter excluding the solvent.

[0016] One embodiment of the method for manufacturing a molded article includes injecting a thermosetting resin composition into a cavity from the injection section of a mold, while exhausting the gas in the cavity through an air vent, and then heating and curing the mixture, wherein the temperature of the mold when injecting the thermosetting resin composition is T°C, the spiral flow value of the thermosetting resin composition at T+10°C is 80-120 cm, and the thickness of the air vent is 15-55 μm. In order to reduce the generation of voids without generating burrs, it is necessary to discharge only gas through the air vent without allowing material to flow through it. The inventors have found that by combining a spiral flow value within a specific range with an air vent thickness, it is possible to suppress the outflow of material from the air vent while reducing the generation of voids due to poor gas release.

[0017] The thermosetting resin composition may be injected with electronic components already placed in the cavity. The electronic components may be positioned so that they are entirely covered by the thermosetting resin composition, or so that only a portion of them are covered. Examples of electronic components include a stator and a rotor. By injecting the thermosetting resin composition with the stator already placed in the cavity, a stator covered with a molding material, i.e., a molded stator, can be manufactured. A molded stator is a component of a motor.

[0018] <Mold> The mold may be a combination of two or more molds. The mold may be installed in either a vertical molding machine or a horizontal molding machine. A vertical molding machine is a molding machine that clamps the mold in a direction perpendicular to the horizontal plane, and a horizontal molding machine is a molding machine that clamps the mold in a horizontal direction. When molding is performed with electronic components placed in the cavity, it is preferable to install the mold in a vertical molding machine from the viewpoint of preventing displacement of the electronic components. A known transfer molding machine can be used as the molding machine. Below, the structure of an exemplary mold will be described using a mold that is a combination of two molds as an example. For convenience, one mold will be called the upper mold and the other mold the lower mold, but these do not limit the positional relationship of each mold when installed.

[0019] Figure 1A is a schematic diagram of a mold 100 according to one embodiment. In Figure 1A, the mold 100 includes an upper mold 10 having an injection section 12, and a lower mold 14 having a cavity 16, an air vent 18, and a protrusion 30 provided on the mating surface 20. The mating surface refers to the surfaces of each mold that come together when the mold 100 is clamped. The injection section 12 is a through hole in the upper mold 10. The injection section 12 and the air vent 18 are provided to communicate with each other via the cavity 16, so when a thermosetting resin composition is injected from the injection section 12, the gas in the cavity 16 is exhausted through the air vent 18. Since the air vent 18 is in communication with the outside, the gas in the cavity 16 is exhausted to the outside of the mold 100 via the air vent 18. A molded product can be obtained by injecting a thermosetting resin composition into the cavity 16 of the mold 100, which has been heated to a predetermined temperature, and then heat-curing it. The thermosetting resin composition can be injected, for example, by pushing out the thermosetting resin composition placed in a pot with a plunger. When molding is performed with electronic components placed in the cavity 16, for example, with the electronic components fitted into the protrusions 30, a receiving portion (not shown) for accommodating a part of the electronic component, such as a terminal portion, may be provided on the mating surface 20 of the lower mold 10. The receiving portion may be provided on the mating surface of the upper mold 10, or on the mating surfaces of both molds. By providing a receiving portion, only the desired part of the electronic component can be molded. The air vent 18 can also serve as the receiving portion. The method of arranging the electronic components in the cavity 16 is not particularly limited and can be appropriately determined according to the electronic components used, the shape of the target molded body, etc.

[0020] Figure 1B shows the positional relationship between the injection section 12 and the air vent 18 when the mold 100 in Figure 1A is viewed from directly above. From the viewpoint of suppressing the generation of voids, for example, when the flow of the injected material is divided, i.e., two or more flows are formed, due to the presence of a protrusion 30 in the lower mold 14 or an optional electronic component, it is preferable to provide the air vent 18 at the point where the flows of the injected material collide. In Figure 1B, the material is divided from left to right, forming two flows on the upper and lower sides of the protrusion 30, so it is preferable to provide the air vent 18 in the center of the right side.

[0021] Figure 2A is a schematic diagram of a mold 100 according to one embodiment. Unlike Figure 1A, the mold 100 in Figure 2A is also provided with a cavity 16 on the mating surface of the upper mold 10. Thus, the cavity 16 may be provided on either the upper mold 10 or the lower mold 14, or on both. Similarly, the air vent 18 may be provided on either the upper mold 10 or the lower mold 14, or on both.

[0022] Figure 2B shows the positional relationship between the injection section 12 and the air vent 18 when the mold 100 in Figure 2A is viewed from directly above. In Figure 2B, the material flows from left to right, splitting into two flows on the upper and lower sides of the convex section 30. Therefore, it is preferable to provide the air vent 18 in the center of the right side.

[0023] Figure 3A is a schematic diagram of a mold 100 according to one embodiment. Unlike Figure 1A, the mold 100 in Figure 3A has an upper mold 10 with two injection ports 12 and a lower mold 14 with two air vents 18. Figure 3B is a diagram showing the positional relationship between the injection ports 12 and the air vents 18 when the mold 100 in Figure 3A is viewed from directly above. In Figure 3B, since the material forms leftward and rightward flows from each injection port 12 in the central part of the mold 100, it is preferable to provide air vents 18 in the central part on the right and left sides.

[0024] Figure 4A is a schematic diagram of a mold 100 according to one embodiment. Unlike Figure 1A, the mold 100 in Figure 4A has an upper mold 10 with three injection sections 12 and a lower mold 14 with three air vents 18. Figure 4B is a diagram showing the positional relationship between the injection sections 12 and the air vents 18 when the mold 100 of Figure 4A is viewed from directly above. In Figure 4B, since the material forms two-directional flows for each of the three injection sections 12, it is preferable to provide the air vents 18 near the center of the line connecting each injection section 12.

[0025] Figure 5A is a schematic diagram of a mold 100 according to one embodiment. Unlike Figure 1A, the mold 100 in Figure 5A has a resin reservoir 22 on the mating surface 20 of the lower mold 14. The resin reservoir 22 is provided to communicate with the cavity 16 via an air vent 18, so that the gas in the cavity 16 is exhausted into the resin reservoir 22 via the air vent 18. By providing the resin reservoir 22, the length of the air vent flow path, which is prone to generating burrs and resin-derived deposits, can be shortened, making mold cleaning easier.

[0026] Figure 5B shows the positional relationship between the injection section 12, the air vent 18, and the resin reservoir 22 when the mold 100 in Figure 5A is viewed from directly above. In Figure 5B, the material flows from left to right, splitting into two flows on the upper and lower sides of the protrusion 30. Therefore, it is preferable to provide the air vent 18 in the center of the right side of the cavity.

[0027] Figure 6A is a schematic overall view of a mold 100 according to one embodiment and a schematic partial cross-sectional view during injection of a thermosetting resin composition. In the partial cross-sectional view, the dashed line indicates the injection section 12, and the arrows indicate the flow of the thermosetting resin composition. Unlike Figure 1A, the mold 100 in Figure 6A is provided with two sets of cavities 16, an air vent 18, and a protrusion 30 in the lower mold 14. Furthermore, the shape of the injection section 12 in the mold 100 in Figure 6A is different from that of the mold 100 in Figure 1A. Specifically, in Figure 6A, the injection section 12 is composed of a through hole in the upper mold 10 and a flow path provided in the mating surface 20 of the lower mold 14. In Figure 6A, the thermosetting resin composition flows into the cavity 16 from the side of the cavity 16 after passing through the flow path provided in the through hole in the upper mold 10 and the mating surface 20. The injection section 12 and the air vent 18 are arranged to communicate with each other via the cavity 16. Therefore, when the thermosetting resin composition is injected from the injection section 12, the gas in the cavity 16 is exhausted through the air vent 18. In the mold 100 shown in Figure 6A, two molded bodies can be manufactured simultaneously. The mold 100 may have three or more cavities 16.

[0028] Figure 6B shows the positional relationship between the injection section 12 and the air vent 18 when the mold 100 in Figure 6A is viewed from directly above. In the cavity 16 on the right side of Figure 6B, the material flows from left to right, splitting into two flows on the upper and lower sides of the protrusion 30, so it is preferable to provide the air vent 18 in the center of the right side. In the cavity 16 on the left side of Figure 6B, the material flows from right to left, splitting into two flows on the upper and lower sides of the protrusion 30, so it is preferable to provide the air vent 18 in the center of the left side.

[0029] While the structure of an exemplary mold has been described with reference to the drawings, the structure of the mold is not limited to these. For example, the shape of the cavity is not limited to that shown in the drawings and may vary depending on the target molded product. The number of cavities can also be set as appropriate, for example, there may be three or more. The number and position of the injection ports may also be set as appropriate depending on the shape of the molded product, the electronic components to be placed inside, etc. The number and position of the air vents may also be set as appropriate depending on the number and position of the injection ports, etc.

[0030] The thickness of the air vent is 15 to 55 μm. The thickness of the air vent may be 18 μm or more, or 20 μm or more, and may be 50 μm or less, or 40 μm or less. If the thickness of the air vent is 15 μm or more, the gas in the cavity can be easily exhausted, and the generation of voids can be suppressed. If the thickness of the air vent is 55 μm or less, the outflow of material can be suppressed, and the generation of burrs can be suppressed. The thickness of the air vent is the maximum depth of the air vent from the mating surface at the interface between the air vent and the cavity. If the air vent is rectangular, the thickness of the air vent is the height from the bottom or top surface of the air vent to the mating surface. If air vents are provided on both the upper and lower molds to form a single air vent, the thickness of the air vent is the sum of the height from the bottom surface of the air vent to the mating surface and the height from the top surface of the air vent to the mating surface.

[0031] The width of the air vent may be 5 mm or more, 6 mm or more, or 8 mm or more, and may be 15 mm or less, 13 mm or less, or 10 mm or less. The width of the air vent is preferably 5 to 15 mm. If the width of the air vent is 5 mm or more, the gas in the cavity will be more easily exhausted from the air vent. If the width of the air vent is 15 mm or less, the amount of material flowing out from the air vent can be further reduced. The width of the air vent is the maximum length of the air vent in the direction perpendicular to the thickness of the air vent at the interface between the air vent and the cavity.

[0032] The length of the air vent flow path is not particularly limited, but may be, for example, 5 mm or more, or 10 mm or more, or 100 mm or less, or 50 mm or less. From the viewpoint of simplifying mold cleaning, it is preferable that it be 30 mm or less. The length of the air vent flow path is the length of the air vent in the direction of material flow.

[0033] <Molding conditions> The molding conditions may be set appropriately depending on the type of thermosetting resin composition used, the size of the molded product, etc. When the thermosetting resin composition contains an unsaturated polyester resin, the preferred molding temperature is, for example, 120 to 180°C or 120 to 160°C. The molding time is not particularly limited, but may be, for example, 1 to 30 minutes. The molding pressure is not particularly limited, but may be, for example, 1 to 50 MPa.

[0034] <Thermosetting resin composition> The thermosetting resin composition has a spiral flow value of 80 to 120 cm at T+10°C, where T°C is the temperature of the mold when the thermosetting resin composition is injected. If the spiral flow value is 80 cm or higher, the thermosetting resin composition has excellent fluidity, and therefore the occurrence of voids can be suppressed when molded in a mold with an air vent thickness of 15 to 55 μm. If the spiral flow value is 80 cm or higher, the occurrence of chipping due to insufficient filling can be suppressed. If the spiral flow value is 120 cm or less, the occurrence of burrs can be suppressed when molded in a mold with an air vent thickness of 15 to 55 μm. The spiral flow value is measured by the method described in the examples.

[0035] The viscosity of the thermosetting resin composition is preferably 60 to 400 Pa·s, more preferably 100 to 300 Pa·s, and even more preferably 150 to 250 Pa·s. If it is 60 Pa·s or higher, the occurrence of burrs can be further suppressed. If it is 400 Pa·s or lower, the occurrence of voids can be further suppressed. The viscosity of the thermosetting resin composition is measured by the method described in the examples.

[0036] A thermosetting resin composition according to one embodiment contains (B) a thermosetting resin, (C) an ethylenically unsaturated monomer, (D) a thermal polymerization initiator, (E) glass fibers, and (F) an inorganic filler. The thermosetting resin composition may further contain one or more selected from (A) a saturated polyester resin and (G) a thickener.

[0037] [(A) Saturated polyester resin] (A) The saturated polyester resin is a polycondensate of a polyhydric alcohol and a saturated polybasic acid. (A) The saturated polyester resin is preferably a polycondensate of a diol and a saturated polybasic acid, and more preferably a polycondensate of a diol, an aromatic saturated polybasic acid or its acid anhydride, and an aliphatic saturated polybasic acid.

[0038] (A) Saturated polyester resin may be used alone or in combination of two or more types. (A) Using saturated polyester resin suppresses crack formation during molding.

[0039] In this disclosure, styrene monomers and the like contained in commercially available saturated polyester resins are classified as (C) ethylenically unsaturated monomers.

[0040] The polyhydric alcohol is not particularly limited as long as it is a compound having two or more hydroxyl groups. The polyhydric alcohol is preferably one or more selected from the group consisting of diols and triols, and more preferably a diol. Examples of polyhydric alcohols include alkylene glycols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A; polyoxyalkylene polyols such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol; bisphenol A; alkylene oxide-modified bisphenol A such as ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A; and glycerin. From the viewpoint of crack resistance during molding, one or more selected from the group consisting of alkylene glycol and polyoxyalkylene polyol is preferred, polyoxyalkylene glycol is more preferred, and one or more selected from diethylene glycol, dipropylene glycol, and triethylene glycol is even more preferred. In particular, from the viewpoint of improving the durability of the molded article, it is preferable to use polyoxyethylene glycol and polyoxypropylene glycol in combination, and it is even more preferable to use diethylene glycol and dipropylene glycol in combination. The content ratio (molar ratio) of polyoxyethylene glycol to polyoxypropylene glycol or the content ratio (molar ratio) of diethylene glycol to dipropylene glycol is not particularly limited, but from the viewpoint of improving durability, 40:60 to 80:20 is preferred, 50:50 to 70:30 is more preferred, 55:45 to 65:35 is even more preferred, and 58:42 to 63:37 is particularly preferred. The polyhydric alcohol may be used alone or in combination of two or more.

[0041] The saturated polybasic acid is not particularly limited as long as it is a compound or acid anhydride thereof that does not have an ethylenically unsaturated bond and has two or more carboxyl groups, and known compounds can be used. The saturated polybasic acid is preferably a saturated dibasic acid. Examples of saturated polybasic acids include aromatic saturated polybasic acids or acid anhydrides thereof such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, nitrophthalic acid, and halogenated phthalic anhydride; aliphatic saturated polybasic acids such as succinic acid, adipic acid, sebacic acid, oxalic acid, malonic acid, azelaic acid, and glutaric acid; and acid anhydrides of cyclic aliphatic saturated polybasic acids such as hexahydrophthalic anhydride. As the aromatic saturated polybasic acid or its acid anhydride, one or more selected from the group consisting of aromatic saturated dibasic acids and their acid anhydrides are preferred, one or more selected from phthalic acid, phthalic anhydride, isophthalic acid, and terephthalic acid are more preferred, and one or more selected from isophthalic acid and terephthalic acid are even more preferred. As the aliphatic saturated polybasic acid, aliphatic saturated dibasic acid is preferred, aliphatic saturated dibasic acid having 4 to 10 carbon atoms is more preferred, and one or more selected from succinic acid, adipic acid, and sebacic acid are even more preferred. From the viewpoint of crack resistance during molding, it is preferred to use one or more selected from the group consisting of aromatic saturated polybasic acids, their acid anhydrides, and aliphatic saturated polybasic acids, it is more preferred to use an aromatic saturated polybasic acid or its acid anhydride in combination with an aliphatic saturated polybasic acid, and it is even more preferred to use one or more selected from isophthalic acid and terephthalic acid in combination with one or more selected from succinic acid, adipic acid, and sebacic acid. Saturated polybasic acids may be used alone or in combination of two or more types.

[0042] When an aromatic saturated polybasic acid or its acid anhydride is used in combination with an aliphatic saturated polybasic acid, the proportion of the aromatic saturated polybasic acid or its acid anhydride is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more. When an aromatic saturated polybasic acid or its acid anhydride is used in combination with an aliphatic saturated polybasic acid, the proportion of the aromatic saturated polybasic acid or its acid anhydride is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. If the proportion of the aromatic saturated polybasic acid or its acid anhydride is within the above range, the moldability is better and the properties of the molded article can be further enhanced.

[0043] When an aromatic saturated polybasic acid or its acid anhydride is used in combination with an aliphatic saturated polybasic acid, the proportion of the aliphatic saturated polybasic acid is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more. When an aromatic saturated polybasic acid or its acid anhydride is used in combination with an aliphatic saturated polybasic acid, the proportion of the aliphatic saturated polybasic acid is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. If the proportion of the aliphatic saturated polybasic acid is within the above range, crack resistance can be improved.

[0044] When an aromatic saturated polybasic acid or its acid anhydride is used in combination with an aliphatic saturated polybasic acid, (A) the molar ratio of the structure derived from the aromatic saturated polybasic acid or its acid anhydride to the structure derived from the aliphatic saturated polybasic acid in the saturated polyester resin is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40.

[0045] When an aromatic saturated polybasic acid or its acid anhydride is used in combination with an aliphatic saturated polybasic acid, the structures derived from these may be uniformly dispersed within the molecules of the saturated polyester resin (A), or they may be unevenly distributed within the molecules. From the viewpoint of crack resistance during molding, it is preferable that the saturated polyester resin (A) contains a block (X) which is a polycondensate of a diol and an aromatic saturated polybasic acid or its acid anhydride, with a weight-average molecular weight of 3000 to 5000, and a block (Y) which is a polycondensate of a diol and an aliphatic saturated polybasic acid. In the saturated polyester resin (A) containing blocks (X) and (Y), the molar ratio of the structure derived from the aromatic saturated polybasic acid or its acid anhydride to the structure derived from the aliphatic saturated polybasic acid is preferably 20:80 to 80:20, more preferably 30:70 to 70:30, and even more preferably 40:60 to 60:40.

[0046] In a saturated polyester resin (A) containing block (X) and block (Y), structures derived from aromatic saturated polybasic acids or their acid anhydrides may be scattered in the parts other than block (X) and block (Y).

[0047] The weight-average molecular weight of block (X) is preferably 3000 or more, more preferably 3500 or more. The weight-average molecular weight of block (X) is preferably 5000 or less, more preferably 4500 or less. If the weight-average molecular weight of block (X) is within the above range, the crack resistance during molding is good.

[0048] The aromatic saturated polybasic acid or its acid anhydride constituting block (X) is preferably one or more selected from the group consisting of aromatic saturated dibasic acids and their acid anhydrides, more preferably one or more selected from phthalic acid, phthalic anhydride, isophthalic acid, and terephthalic acid, and even more preferably one or more selected from isophthalic acid and terephthalic acid.

[0049] As the aliphatic saturated polybasic acid constituting block (Y), an aliphatic saturated dibasic acid is preferred, an aliphatic saturated dibasic acid having 4 to 10 carbon atoms is more preferred, and one or more selected from succinic acid, adipic acid, and sebacic acid are even more preferred.

[0050] Preferred combinations of polyhydric alcohols and saturated polybasic acids include diols and saturated dibasic acids, and more preferably polyoxyalkylene glycols and saturated dibasic acids. More specifically, examples include combinations of diethylene glycol and isophthalic acid, diethylene glycol and adipic acid, dipropylene glycol and isophthalic acid, dipropylene glycol and adipic acid, diethylene glycol, isophthalic acid and adipic acid, dipropylene glycol, isophthalic acid and adipic acid, and diethylene glycol, dipropylene glycol, isophthalic acid and adipic acid. Among these, the combinations of diethylene glycol, isophthalic acid and adipic acid, dipropylene glycol, isophthalic acid and adipic acid, and diethylene glycol, dipropylene glycol, isophthalic acid and adipic acid are preferred because they exhibit good crack resistance during molding.

[0051] (A) The weight-average molecular weight of the saturated polyester resin is preferably 9500 or more, more preferably 9800 or more, and even more preferably 10000 or more. (A) The weight-average molecular weight of the saturated polyester resin is preferably 13500 or less, more preferably 13000 or less, and even more preferably 12500 or less. When the weight-average molecular weight is within the above range, crack formation during molding is further suppressed. Although not bound by any particular theory, it is thought that setting the weight-average molecular weight of the saturated polyester resin (A) within the above range improves the dispersibility of components (C) to (G), thereby suppressing crack formation during molding. The weight-average molecular weight of the saturated polyester resin (A) can be adjusted by the reaction time when synthesizing the saturated polyester resin (A). Specifically, the longer the reaction time, the larger the weight-average molecular weight, and the shorter the reaction time, the smaller the weight-average molecular weight.

[0052] The content of (A) saturated polyester resin in the thermosetting resin composition is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (A) saturated polyester resin in the thermosetting resin composition is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (A) saturated polyester resin in the thermosetting resin composition is preferably 5 to 30 parts by mass, more preferably 8 to 25 parts by mass, and even more preferably 10 to 20 parts by mass, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. If the content of (A) saturated polyester resin in the thermosetting resin composition is 5 parts by mass or more, crack generation during molding can be further suppressed. If the content of (A) saturated polyester resin in the thermosetting resin composition is 30 parts by mass or less, the moldability of the thermosetting resin composition and the mechanical properties of the molded article are better.

[0053] ((A) Method for synthesizing saturated polyester resin) (A) Saturated polyester resin can be synthesized using the above raw materials by known methods. (A) Various conditions in the synthesis of saturated polyester resin are set appropriately according to the raw materials used and their amounts.

[0054] Generally, esterification reactions can be carried out under pressure or reduced pressure at a temperature of 140°C to 230°C in an inert gas stream such as nitrogen gas. Esterification catalysts can be used in the esterification reaction as needed. Examples of known esterification catalysts include manganese acetate, dibutyltin oxide, stannous oxalate, zinc acetate, and cobalt acetate. Esterification catalysts may be used individually or in combination of two or more.

[0055] It is preferable that the equivalent amount of hydroxyl groups in the polyhydric alcohol be in the range of 0.9 to 1.2 relative to the total amount of carboxyl groups in the saturated polybasic acid.

[0056] When an aromatic saturated polybasic acid or its acid anhydride is used in combination with an aliphatic saturated polybasic acid, the structures derived from these may be uniformly dispersed within the molecules of the saturated polyester resin (A). Such a saturated polyester resin (A) can be obtained by adding both to a reaction vessel at once and carrying out an esterification reaction.

[0057] From the viewpoint of crack resistance during molding, it is preferable that the structure derived from the aromatic saturated polybasic acid or its acid anhydride and the structure derived from the aliphatic saturated polybasic acid are each unevenly distributed within the molecule. Such a saturated polyester resin (A) can be obtained by first adding one of the saturated polybasic acids to the reaction vessel, allowing the esterification reaction to proceed until a certain amount of saturated polybasic acid has been consumed, then adding the other saturated polybasic acid to the reaction vessel and allowing the esterification reaction to proceed until the desired weight-average molecular weight is obtained. For example, such a saturated polyester resin (A) can be synthesized as follows: first add the total amount of the aromatic saturated polybasic acid or its acid anhydride and the aliphatic saturated polybasic acid, plus an equivalent amount of polyhydric alcohol, and the aromatic saturated polybasic acid or its acid anhydride to the reaction vessel, allow the esterification reaction to proceed until a certain amount of aromatic saturated polybasic acid or its acid anhydride has been consumed, then add the aliphatic saturated polybasic acid to the reaction vessel and allow the esterification reaction to proceed.

[0058] A saturated polyester resin (A) containing block (X), which is a polycondensate of a diol and an aromatic saturated polybasic acid or its acid anhydride, and block (Y), which is a polycondensate of a diol and an aliphatic saturated polybasic acid, can be synthesized, for example, as follows: First, an equivalent amount of diol to the total amount of aromatic saturated polybasic acid or its acid anhydride and aliphatic saturated polybasic acid, and an aromatic saturated polybasic acid or its acid anhydride are placed in a reaction vessel, and the esterification reaction proceeds until a certain amount of aromatic saturated polybasic acid or its acid anhydride is consumed, at which point the aliphatic saturated polybasic acid is added to the reaction vessel and the esterification reaction proceeds.

[0059] The weight-average molecular weight of block (X) can be adjusted by the timing of the addition of the aliphatic saturated polybasic acid added later. For example, the acid value of the reaction solution, i.e., the remaining amount of the aromatic saturated polybasic acid or its acid anhydride added earlier, can be traced, and the aliphatic saturated polybasic acid can be added when the desired amount is reached. From the viewpoint of crack resistance, the acid value of the reaction solution at the time of addition of the aliphatic saturated polybasic acid is preferably 30 KOH mg / g or less, more preferably 20 KOH mg / g or less, and even more preferably 10 KOH mg / g or less. The acid value of the reaction solution at the time of addition of the aliphatic saturated polybasic acid may be 1 KOH mg / g or more, 3 KOH mg / g or more, or 5 KOH mg / g or more.

[0060] [(B) Thermosetting resin] (B) As the thermosetting resin, a thermosetting resin commonly used for sealing material applications can be used. For example, a resin having functional groups that can form a crosslinked structure when the thermosetting resin composition is heat-cured is preferred. In particular, (C) a resin having multiple ethylenically unsaturated groups as functional groups is preferred from the viewpoint that it can also react with ethylenically unsaturated monomers.

[0061] (B)Specific examples of thermosetting resins include (B-1) unsaturated polyester resin, (B-2) vinyl ester resin, (B-3) urethane (meth)acrylate resin, (B-4) diallyl phthalate resin, (B-5) epoxy resin, etc. (B) Thermosetting resins may be used alone or in combination of two or more types. (B) Thermosetting resins preferably contain (B-1) unsaturated polyester resin. (B-1) By using unsaturated polyester resin, molded articles with excellent mechanical strength and heat resistance can be obtained.

[0062] The content of (B) thermosetting resin in the thermosetting resin composition is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (B) thermosetting resin in the thermosetting resin composition is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. When the content of (B) thermosetting resin in the thermosetting resin composition is 20 parts by mass or more, the mechanical strength of the molded article is good. When the content of (B) thermosetting resin in the thermosetting resin composition is 80 parts by mass or less, the viscosity of the thermosetting resin composition can be adjusted to an appropriate range, and the moldability is better.

[0063] <(B-1) Unsaturated polyester resin> (B-1) The unsaturated polyester resin is a polycondensate of a polyhydric alcohol and an unsaturated polybasic acid, or a polycondensate of a polyhydric alcohol, an unsaturated polybasic acid and a saturated polybasic acid, and is not particularly limited. (B-1) The unsaturated polyester resin is preferably a polycondensate of a diol, an unsaturated polybasic acid and an optional saturated polybasic acid, more preferably a polycondensate of a diol containing propylene glycol, an unsaturated polybasic acid and an optional saturated polybasic acid, and even more preferably a polycondensate of a diol containing propylene glycol and neopentyl glycol, an unsaturated polybasic acid and an optional aromatic saturated polybasic acid.

[0064] (B-1) Unsaturated polyester resin may be used alone or in combination of two or more types.

[0065] In this disclosure, reactive diluents such as styrene monomers contained in commercially available unsaturated polyester resins are classified as (C) ethylenically unsaturated monomers.

[0066] The polyhydric alcohol is not particularly limited as long as it is a compound having two or more hydroxyl groups. The polyhydric alcohol is preferably one or more selected from the group consisting of diols and triols, and more preferably a diol. Examples of polyhydric alcohols include alkylene glycols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 1,4-cyclohexanedimethanol, and hydrogenated bisphenol A; polyoxyalkylene polyols such as diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol; bisphenol A; alkylene oxide-modified bisphenol A such as ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A; and glycerin. From the viewpoint of crack resistance during molding, alkylene glycol is preferred, alkylene glycol having 2 to 6 carbon atoms is more preferred, one or more selected from ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, and neopentyl glycol are even more preferred, and propylene glycol is particularly preferred. From the viewpoint of improving the durability of the molded article, it is preferable to use propylene glycol and neopentyl glycol in combination. From the viewpoint of chemical resistance, it is preferable to use propylene glycol and hydrogenated bisphenol A in combination. Polyhydric alcohols may be used alone or in combination of two or more.

[0067] The unsaturated polybasic acid is not particularly limited as long as it has an ethylenically unsaturated bond and two or more carboxyl groups, or an acid anhydride thereof; known compounds can be used. In particular, unsaturated polybasic acids having 4 to 6 carbon atoms or their acid anhydrides are preferred because they are less expensive and yield a thermosetting resin composition with superior mechanical strength and heat resistance of the molded article. The unsaturated polybasic acid is preferably an unsaturated dibasic acid. Examples of unsaturated polybasic acids include maleic acid, maleic anhydride, fumaric acid, citraconic acid, itaconic acid, and chloromaleic acid. More preferably, one or more selected from fumaric acid, maleic acid, maleic anhydride, and itaconic acid are used. The unsaturated polybasic acid may be used alone or in combination of two or more.

[0068] Preferred combinations of polyhydric alcohols and unsaturated polybasic acids include diols and unsaturated dibasic acids, and more preferably alkylene glycols and unsaturated dibasic acids having 4 to 6 carbon atoms. More specifically, examples include combinations of maleic anhydride, propylene glycol and neopentyl glycol; maleic anhydride and propylene glycol; fumaric acid and propylene glycol; maleic anhydride, propylene glycol and neopentyl glycol and hydrogenated bisphenol A; and maleic anhydride, fumaric acid, propylene glycol and neopentyl glycol and hydrogenated bisphenol A. Combinations of maleic anhydride, propylene glycol and neopentyl glycol, and maleic anhydride and propylene glycol are preferred because they are less expensive and improve crack resistance during molding and the durability of molded products.

[0069] The saturated polybasic acid is not particularly limited as long as it is a compound or acid anhydride thereof that does not have an ethylenically unsaturated bond and has two or more carboxyl groups; known compounds can be used. Examples of saturated polybasic acids include aromatic saturated polybasic acids or acid anhydrides thereof such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, nitrophthalic acid, and halogenated phthalic anhydride; aliphatic saturated polybasic acids such as succinic acid, adipic acid, sebacic acid, oxalic acid, malonic acid, azelaic acid, and glutaric acid; and acid anhydrides of cyclic aliphatic saturated polybasic acids such as hexahydrophthalic anhydride. The saturated polybasic acid may be used alone or in combination of two or more types.

[0070] (B) The content of (B-1) unsaturated polyester resin in the thermosetting resin is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. When the content of (B-1) unsaturated polyester resin is 75% by mass or more, more appropriate moldability, fluidity, and curing shrinkage can be ensured. (B) There is no particular upper limit to the content of (B-1) unsaturated polyester resin in the thermosetting resin. For example, it may be 100% by mass, 97% by mass, or 95% by mass.

[0071] (B) The thermosetting resin preferably contains at least (B-1-1) an unsaturated polyester resin, the (B-1-1) unsaturated polyester resin being a polycondensate of a diol and an unsaturated polybasic acid, and containing structures derived from propylene glycol and neopentyl glycol. (B) The thermosetting resin more preferably contains (B-1-1) an unsaturated polyester resin and (B-1-2) an unsaturated polyester resin, the (B-1-2) unsaturated polyester resin being a polycondensate of a diol and an unsaturated polybasic acid, and the (B-1-2) unsaturated polyester resin containing structures derived from propylene glycol but not from neopentyl glycol.

[0072] (B) The content of (B-1-1) unsaturated polyester resin in the thermosetting resin is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. When the content of (B-1-1) unsaturated polyester resin is 75% by mass or more, more appropriate moldability, fluidity, and curing shrinkage can be ensured. (B) There is no particular upper limit to the content of (B-1-1) unsaturated polyester resin in the thermosetting resin. For example, it may be 100% by mass, 97% by mass, or 95% by mass.

[0073] When (B-1-1) unsaturated polyester resin and (B-1-2) unsaturated polyester resin are used in combination, the total content of (B-1-1) unsaturated polyester resin and (B-1-2) unsaturated polyester resin in (B) thermosetting resin is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more. When the total content of (B-1-1) unsaturated polyester resin and (B-1-2) unsaturated polyester resin is 75% by mass or more, more appropriate moldability, fluidity, and curing shrinkage can be ensured. The upper limit of the total content of (B-1-1) unsaturated polyester resin and (B-1-2) unsaturated polyester resin in (B) thermosetting resin is not particularly limited. For example, it may be 100% by mass, 97% by mass, or 95% by mass.

[0074] When (B-1-1) unsaturated polyester resin and (B-1-2) unsaturated polyester resin are used in combination, the ratio of (B-1-1) unsaturated polyester resin to the total of (B-1-1) unsaturated polyester resin and (B-1-2) unsaturated polyester resin is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 60% by mass.

[0075] In another embodiment, the content of (B-1-1) unsaturated polyester resin in (B) thermosetting resin is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. The content of (B-1-1) unsaturated polyester resin in (B) thermosetting resin is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. The content of (B-1-2) unsaturated polyester resin in (B) thermosetting resin is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. The content of (B-1-2) unsaturated polyester resin in (B) thermosetting resin is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

[0076] The weight-average molecular weight of the (B-1) unsaturated polyester resin is not particularly limited. The weight-average molecular weight of the (B-1) unsaturated polyester resin is preferably 2,000 to 50,000, more preferably 5,000 to 50,000, even more preferably 10,000 to 50,000, and particularly preferably 13,000 to 35,000. If the weight-average molecular weight is 2,000 to 50,000, the moldability of the thermosetting resin composition is further improved. If the weight-average molecular weight is 2,000 to 50,000, crack generation during molding is further suppressed. Although not bound by any theory, it is believed that setting the weight-average molecular weight of the (B-1) unsaturated polyester resin within the above range improves the dispersibility of components (C) to (G) and suppresses crack generation during molding.

[0077] The degree of unsaturation of the (B-1) unsaturated polyester resin is preferably 50 to 100 mol%, more preferably 60 to 100 mol%, and even more preferably 70 to 100 mol%. When the degree of unsaturation is within the above range, the moldability of the thermosetting resin composition containing the (B-1) unsaturated polyester resin is improved.

[0078] (B-1) The degree of unsaturation of an unsaturated polyester resin can be calculated using the following formula, based on the number of moles of unsaturated polybasic acid and saturated polybasic acid used as raw materials. Degree of unsaturation (mol%) = {(moles of unsaturated polybasic acid × number of ethylenically unsaturated bonds per molecule of unsaturated polybasic acid) / (moles of unsaturated polybasic acid + moles of saturated polybasic acid)} × 100

[0079] ((B-1) Method for synthesizing unsaturated polyester resin) (B-1) Unsaturated polyester resin can be synthesized using the above raw materials by known methods. (B-1) Various conditions in the synthesis of unsaturated polyester resin are set appropriately according to the raw materials used and their quantities.

[0080] Generally, esterification reactions can be carried out under pressure or reduced pressure at a temperature of 140°C to 230°C in an inert gas stream such as nitrogen gas. Esterification catalysts can be used in the esterification reaction as needed. Examples of known esterification catalysts include manganese acetate, dibutyltin oxide, stannous oxalate, zinc acetate, and cobalt acetate. Esterification catalysts may be used individually or in combination of two or more.

[0081] To increase molecular weight by improving the reaction rate, it is preferable that the equivalent amount of hydroxyl groups of the polyhydric alcohol be in the range of 0.9 to 1.2 relative to the total amount of carboxyl groups of the unsaturated polybasic acid and any saturated polybasic acid.

[0082] <(B-2) Vinyl ester resin> (B-2) Vinyl ester resins are generally compounds having an ethylenically unsaturated bond, obtained by a ring-opening reaction between (a) an epoxy group in an epoxy compound having two or more epoxy groups and (b) a carboxyl group of an unsaturated monobasic acid having an ethylenically unsaturated bond and a carboxyl group. (B-2) Vinyl ester resins are described in, for example, the Polyester Resin Handbook (Nikkan Kogyo Shimbun, published in 1988).

[0083] (B-2) Vinyl ester resin may be used alone or in combination of two or more types. (B-2) Vinyl ester resin is generally used diluted with (C) ethylenically unsaturated monomer for ease of handling. By using (B-2) vinyl ester resin, the material cost of the thermosetting resin composition can be reduced.

[0084] (B-2) The weight-average molecular weight (Mw) of the vinyl ester resin can be adjusted according to the desired physical properties, but a range of 500 to 5,000 is preferred from a handling standpoint.

[0085] (a) epoxy compounds (a) The epoxy compound is not particularly limited as long as it is a compound having two or more epoxy groups. Preferably, it is one or more selected from the group consisting of bisphenol-type epoxy compounds and novolacphenol-type epoxy compounds, and more preferably a bisphenol-type epoxy compound. (a) By using (B-2) vinyl ester resin using an epoxy compound as a raw material, the mechanical strength and corrosion resistance of the molded article are further improved.

[0086] Examples of bisphenol-type epoxy compounds include those obtained by reacting bisphenol compounds such as bisphenol A, bisphenol F, bisphenol S, and tetrabromobisphenol A with epichlorohydrin and / or methylepichlorohydrin; and those obtained by reacting a compound obtained by glycidyl etherifying one or more of the above bisphenol compounds with a condensate of one or more of the above bisphenol compounds with epichlorohydrin and / or methylepichlorohydrin. From the viewpoint of durability, the reaction product of a bisphenol compound and epichlorohydrin is preferred, and the reaction product of bisphenol A and epichlorohydrin is more preferred.

[0087] Examples of novolac phenol-type epoxy compounds include those obtained by reacting phenol novolac or cresol novolac with epichlorohydrin and / or methyl epichlorohydrin.

[0088] ((b) Unsaturated monobasic acid) (b) The unsaturated monobasic acid is not particularly limited as long as it is a monocarboxylic acid having an ethylenically unsaturated bond. Preferably, it is methacrylic acid, acrylic acid, crotonic acid, cinnamic acid, etc., more preferably acrylic acid or methacrylic acid, and even more preferably methacrylic acid from the viewpoint of corrosion resistance of the molded article.

[0089] ((B-2) Method for synthesizing vinyl ester resin) (B-2) Vinyl ester resins can be synthesized by known synthesis methods. For example, one method involves adding (b) an unsaturated monobasic acid in the presence of an esterification catalyst and (a) an epoxy compound in a heat-stirred reaction vessel and reacting at 70 to 150°C, preferably 80 to 140°C, and more preferably 90 to 130°C.

[0090] As esterification catalysts, known catalysts such as triethylamine, N,N-dimethylbenzylamine, N,N-dimethylaniline, tertiary amines such as diazabicyclooctane, triphenylphosphine, and diethylamine hydrochloride can be used.

[0091] (a) The mixing ratio of the epoxy compound and (b) the unsaturated monobasic acid is preferably such that the total amount of carboxyl groups of (b) the unsaturated monobasic acid is 0.3 to 1.2 moles, more preferably 0.4 to 1.1 moles, and even more preferably 0.5 to 1.0 moles, for every 1 mole of epoxy groups of (a) the epoxy compound. If the total amount of carboxyl groups of (b) the unsaturated monobasic acid is 0.3 moles or more, a molded article with sufficient hardness can be obtained when the thermosetting resin composition is cured. On the other hand, if the total amount of carboxyl groups of (b) the unsaturated monobasic acid is 1.2 moles or less, the amount of unreacted (b) unsaturated monobasic acid can be reduced when synthesizing (B-2) vinyl ester resin, so a molded article with excellent mechanical strength can be obtained.

[0092] When a thermosetting resin composition is heat-cured, unreacted (b) unsaturated monobasic acid may volatilize; therefore, the content of unreacted (b) unsaturated monobasic acid should be reduced as much as possible. For example, the content of unreacted (b) unsaturated monobasic acid relative to the total amount of (B-2) vinyl ester resin and unreacted (b) unsaturated monobasic acid is preferably 5% by mass or less, and more preferably 3% by mass or less.

[0093] (B) The content of (B-2) vinyl ester resin in the thermosetting resin may be 1% by mass or more, 3% by mass or more, or 5% by mass or more. (B) There is no particular upper limit to the content of (B-2) vinyl ester resin in the thermosetting resin. For example, it may be 25% by mass, 20% by mass, or 10% by mass.

[0094] <(B-3) Urethane (meth)acrylate resin> (B-3) Examples of urethane (meth)acrylate resins include resins obtained by introducing (meth)acryloyl groups to the hydroxyl groups or isocyanate groups at both ends of a polyurethane obtained by reacting a polyhydric isocyanate with a polyhydric alcohol.

[0095] As the polyhydric alcohol, any of the compounds listed above as raw materials for (B-1) unsaturated polyester resins can be used without particular limitation.

[0096] Examples of polyvalent isocyanates include aliphatic polyvalent isocyanates such as hexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate, and trimethylhexane diisocyanate; cyclic aliphatic polyvalent isocyanates such as hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4 (or 2,6)-diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), and 1,3-(isocyanatomethyl)cyclohexane; aromatic polyvalent isocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate; and adducts, isocyanurates, and biuret derivatives of these polyvalent isocyanates. Polyvalent isocyanates may be used alone or in combination of two or more.

[0097] When introducing a (meth)acryloyl group, for example, a method can be used in which a hydroxyl group-containing (meth)acrylic compound is reacted with the terminal isocyanate group, or a method can be used in which an isocyanate group-containing (meth)acrylic compound such as 2-(meth)acryloyloxyethyl isocyanate, 2-(meth)acryloyloxypropyl isocyanate, or 1,1-bis(acryloyloxymethyl)ethyl isocyanate is reacted with the terminal hydroxyl group. Examples of hydroxyl group-containing (meth)acrylic compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, tris(hydroxyethyl)isocyanurate di(meth)acrylate, pentaestritol tri(meth)acrylate, glycerin mono(meth)acrylate, and hydroxyethyl acrylamide, with 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, caprolactone-modified hydroxyalkyl (meth)acrylate, and hydroxyethyl acrylamide being preferred. The isocyanate group-containing (meth)acrylic compounds and the hydroxyl group-containing (meth)acrylic compounds may be used individually or in combination of two or more.

[0098] (B) The content of (B-3) urethane (meth)acrylate resin in the thermosetting resin may be 1% by mass or more, 3% by mass or more, or 5% by mass or more. (B) There is no particular upper limit to the content of (B-3) urethane (meth)acrylate resin in the thermosetting resin. For example, it may be 25% by mass, 20% by mass, or 10% by mass.

[0099] <(B-4) Diallyl phthalate resin> (B-4) Diallyl phthalate resin is an oligomer obtained by the esterification reaction of diallyl phthalate and a polyhydric alcohol, and conventionally known ones can be used without particular limitation. (B-4) Diallyl phthalate resin may be used alone or in combination of two or more types.

[0100] (B) The content of (B-4) diallyl phthalate resin in the thermosetting resin may be 1% by mass or more, 3% by mass or more, or 5% by mass or more. (B) There is no particular upper limit to the content of (B-4) diallyl phthalate resin in the thermosetting resin. For example, it may be 25% by mass, 20% by mass, or 10% by mass.

[0101] <(B-5) Epoxy resin> (B-5) As the epoxy resin, the compounds described in section (a) epoxy compounds of (B-2) vinyl ester resins can be used. (B-5) The epoxy resin may be used alone or in combination of two or more types.

[0102] (B) The content of (B-5) epoxy resin in the thermosetting resin may be 1% by mass or more, 3% by mass or more, or 5% by mass or more. (B) There is no particular upper limit to the content of (B-5) epoxy resin in the thermosetting resin. For example, it may be 25% by mass, 20% by mass, or 10% by mass.

[0103] [(C) Ethylene-unsaturated monomers] (C) The ethylenically unsaturated monomer is not particularly limited as long as it is a monomer having an ethylenically unsaturated bond. (C) The ethylenically unsaturated monomer may be used alone or in combination of two or more types.

[0104] Specifically, vinyl compounds such as styrene, vinyltoluene, t-butylstyrene, methoxystyrene, divinylbenzene, vinylnaphthalene; methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, furfuryl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate Examples of (meth)acrylates include acrylate, phenoxyethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, allyl (meth)acrylate, isobornyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, etc.; cyclic unsaturated compounds such as acenaphthylene and norbornene are also included. (B) From the viewpoint of copolymerization with thermosetting resins, vinyl compounds are preferred, more preferably one or more selected from styrene, vinyltoluene, t-butylstyrene, and methoxystyrene, and even more preferably styrene.

[0105] The content of (C) ethylenically unsaturated monomer in the thermosetting resin composition is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (C) ethylenically unsaturated monomer in the thermosetting resin composition is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 60 parts by mass or less, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. When the content of (C) ethylenically unsaturated monomer in the thermosetting resin composition is 20 parts by mass or more, the viscosity of the thermosetting resin composition can be adjusted to an appropriate range, and the moldability is better. When the content of (C) ethylenically unsaturated monomer in the thermosetting resin composition is 80 parts by mass or less, the mechanical strength of the molded article is good.

[0106] [(D) Thermal polymerization initiator] (D) The thermal polymerization initiator is not particularly limited as long as it is a polymerization initiator that generates radicals upon heating. Examples include organic peroxides such as diacyl peroxide, peroxyester, hydroperoxide, dialkyl peroxide, ketone peroxide, peroxyketal, alkyl perester, and parkervonate.

[0107] (D) Among these organic peroxides, 1,1-di-t-hexylperoxycyclohexane, t-hexylperoxyisopropyl carbonate, t-butylperoxyoctoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, benzoyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, t-butylperoxybenzoate, dicumyl peroxide, and di-t-butyl peroxide are preferred as thermal polymerization initiators. (D) The thermal polymerization initiators may be used alone or in combination of two or more.

[0108] The content of (D) thermal polymerization initiator in the thermosetting resin composition is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 3 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (D) thermal polymerization initiator in the thermosetting resin composition is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. When the content of (D) thermal polymerization initiator in the thermosetting resin composition is 0.5 parts by mass or more, the curing reaction during molding of the thermosetting resin composition proceeds uniformly, and the physical properties and appearance of the molded article are good. When the content of (D) thermal polymerization initiator in the thermosetting resin composition is 20 parts by mass or less, the storage stability of the thermosetting resin composition is good, and handling is improved.

[0109] [(E) Glass fiber] (E) Glass fibers are fibrous materials with an aspect ratio of 3 or more. By using (E) glass fibers, the spiral flow value of the thermosetting resin composition can be adjusted. The aspect ratio is measured by the microscopy method described in JIS Z 8900-1:2008 "Particles for Verification of Particle Size Measuring Devices". From the viewpoint of the fluidity of the thermosetting resin composition, (E) glass fibers are preferably chopped strand glass or milled fibers.

[0110] (E) The fiber length of the glass fibers is preferably 6 mm or less, more preferably 5 mm or less, and even more preferably 4 mm or less. When the fiber length is 6 mm or less, the fluidity of the thermosetting resin composition is good and voids are less likely to occur. (E) The fiber length of the glass fibers is preferably 0.1 mm or more, more preferably 0.5 mm or more, and even more preferably 1 mm or more. When the fiber length is 0.1 mm or more, the occurrence of burrs can be further suppressed. (E) The fiber length of the glass fibers is the number average value of the values ​​measured from 100 fibers randomly sampled with a micrometer of an optical microscope.

[0111] (E) The average fiber diameter of the glass fibers is preferably 3 to 100 μm, and more preferably 5 to 30 μm.

[0112] The content of (E) glass fibers in the thermosetting resin composition is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (E) glass fibers in the thermosetting resin composition is preferably 70 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 40 parts by mass or less, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. If the content of (E) glass fibers in the thermosetting resin composition is 10 parts by mass or more, the occurrence of burrs can be further suppressed. If the content of (E) glass fibers in the thermosetting resin composition is 70 parts by mass or less, the fluidity of the thermosetting resin composition is good and voids are less likely to occur.

[0113] [(F) Inorganic filler] (F) As the inorganic filler, particulate matter known in the art of the present invention can be used. In this specification, particulate matter is a substance with an aspect ratio of less than 3. (F) By using inorganic filler, it is possible to adjust the spiral flow value of the thermosetting resin composition, reduce the molding shrinkage rate of the molded article, or improve the strength of the molded article.

[0114] (F) Examples of inorganic fillers include calcium carbonate, silica, aluminum oxide, aluminum hydroxide, barium sulfate, calcium sulfate, calcium oxide, wollastonite, clay, kaolin, mica, gypsum, anhydrous silicic acid, and glass powder. Calcium carbonate, aluminum oxide, and aluminum hydroxide are preferred because they are inexpensive. (F) Inorganic fillers may be used individually or in combination of two or more types.

[0115] (F) The average particle size of the inorganic filler is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. (F) The average particle size of the inorganic filler is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less. (F) If the average particle size of the inorganic filler is 0.1 μm or more, particle aggregation can be suppressed. (F) If the average particle size of the inorganic filler is 100 μm or less, the moldability of the thermosetting resin composition is good.

[0116] In this specification, "average particle size" refers to the 50% particle size (D50) in the volume-based cumulative particle size distribution measured by a laser diffraction / scattering particle size distribution analyzer (Microtrac-Bell Corporation, FRA), using a dispersion obtained by adding 1 g of the substance to be measured to 30 mL of distilled water and dispersing it in an ultrasonic cleaner for 10 minutes as the measurement sample.

[0117] (F) The shape of the inorganic filler is not particularly limited. Examples include a nearly perfect sphere, ellipsoid, flake-like shape, amorphous shape, etc.

[0118] The content of (F) inorganic filler in the thermosetting resin composition is preferably 150 parts by mass or more, more preferably 250 parts by mass or more, and even more preferably 350 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (F) inorganic filler in the thermosetting resin composition is preferably 600 parts by mass or less, more preferably 500 parts by mass or less, and even more preferably 400 parts by mass or less, based on 100 parts by mass of the total amount of (B) unsaturated polyester resin and (C) ethylenically unsaturated monomer. If the content of (F) inorganic filler in the thermosetting resin composition is 150 parts by mass or more, the mechanical properties of the molded article are better. If the content of (F) inorganic filler in the thermosetting resin composition is 600 parts by mass or less, the (F) inorganic filler is dispersed more uniformly in the thermosetting resin composition, and a homogeneous molded article can be produced.

[0119] [(G) Thickener] (G) The thickening agent is one or more selected from calcium hydroxide, magnesium oxide, and magnesium hydroxide. (G) The spiral flow value of the thermosetting resin composition can be adjusted by using the thickening agent.

[0120] (G) The shape of the thickener is not particularly limited. Examples include approximately spherical, ellipsoidal, flaky, amorphous, etc.

[0121] The content of (G) thickener in the thermosetting resin composition is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.4 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (G) thickener in the thermosetting resin composition is preferably 9 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 3 parts by mass or less, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. When the content of (G) thickener in the thermosetting resin composition is within the above range, the fillability of the thermosetting resin composition in the mold is better.

[0122] [(H) Other low-shrinkage agents] The thermosetting resin composition may optionally contain (H) other low-shrinkage agents other than (A) saturated polyester resin. (H) The other low-shrinkage agents are not particularly limited and those known in the art of the present invention can be used. (H) Thermoplastic resins are preferred as the other low-shrinkage agents. (H) Examples of other low-shrinkage agents include polystyrene, polyethylene, polymethyl methacrylate, polyvinyl acetate, polycaprolactone, styrene-butadiene rubber, etc. Among these, polystyrene is preferred from the viewpoint of reducing the shrinkage rate of the molded article. (H) The other low-shrinkage agents may be used alone or in combination of two or more.

[0123] The content of (H) other low-shrinkage agents in the thermosetting resin composition may be 1 part by mass or more, 3 parts by mass or more, or 5 parts by mass or more, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. The content of (H) other low-shrinkage agents in the thermosetting resin composition may be 30 parts by mass or less, 20 parts by mass or less, or 10 parts by mass or less, based on 100 parts by mass of the total amount of (B) thermosetting resin and (C) ethylenically unsaturated monomer. If the content of (H) other low-shrinkage agents in the thermosetting resin composition is 1 part by mass or more, the shrinkage rate of the molded article will be reduced, and the desired dimensional accuracy can be obtained in the molded product. If the content of (H) other low-shrinkage agents in the thermosetting resin composition is 30 parts by mass or less, the moldability of the thermosetting resin composition and the mechanical properties of the molded article will be better.

[0124] [(I) Release agent] The thermosetting resin composition may optionally contain (I) a release agent. The (I) release agent is not particularly limited and any known in the art of the present invention can be used. Examples of (I) release agents include stearic acid, oleic acid, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, stearate amide, oleic acid amide, silicone oil, synthetic wax, etc. The (I) release agent may be used alone or in combination of two or more types.

[0125] (I) When a release agent is used, the content is preferably 1 to 40 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 8 to 20 parts by mass, per 100 parts by mass of (B) thermosetting resin. (I) If the content of the release agent is 1 part by mass or more, the release properties of the molded article after molding are good and the productivity of the product is good. On the other hand, (I) if the content of the release agent is 40 parts by mass or less, an article with a good appearance can be obtained without excessive release agent contaminating the surface of the molded article.

[0126] [Other additives] In addition to the above components, the thermosetting resin composition may contain viscosity modifiers such as organic thickeners and viscosity reducers, colorants, polymerization inhibitors, and molding aids, to the extent that they do not impede the effects of the present invention.

[0127] Examples of organic thickeners include isocyanate compounds. Organic thickeners may be used alone or in combination of two or more. The content of the organic thickener can be appropriately adjusted according to the handling properties, fluidity, etc., required of the thermosetting resin composition.

[0128] Colorants are used to color molded articles, etc. Examples of colorants include various dyes, inorganic pigments, and organic pigments. Colorants may be used alone or in combination of two or more. The amount of colorant can be adjusted as appropriate depending on the desired degree of coloring of the molded article.

[0129] Examples of polymerization inhibitors include hydroquinone, trimethylhydroquinone, p-benzoquinone, naphthoquinone, t-butylhydroquinone, catechol, pt-butylcatechol, and 2,6-di-t-butyl-4-methylphenol. Polymerization inhibitors may be used alone or in combination of two or more. The content of polymerization inhibitors can be appropriately adjusted depending on the storage environment, storage period, curing conditions, etc., of the thermosetting resin composition.

[0130] <Method for producing thermosetting resin compositions> Thermosetting resin compositions can be manufactured by mixing the components. Mixing methods include, for example, kneading. There are no particular restrictions on the kneading method; for example, a kneader, disper, planetary mixer, etc., can be used. The kneading temperature is preferably 5°C to 50°C, and more preferably 10°C to 40°C.

[0131] There are no particular restrictions on the order in which the components are mixed when manufacturing a thermosetting resin composition. For example, when using (B-1) unsaturated polyester resin, it is preferable to mix the (B-1) unsaturated polyester resin with some or all of the (C) ethylenically unsaturated monomer before mixing the other components, as this makes it easier to obtain a thermosetting resin composition in which each component is sufficiently dispersed or uniformly mixed. At least a portion of the (C) ethylenically unsaturated monomer may be pre-mixed with the (B-1) unsaturated polyester resin so as to act as a solvent, dispersion medium, etc. [Examples]

[0132] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0133] (A) Examples of saturated polyester resin synthesis are shown below.

[0134] The following ingredients will be used: Diol: Diethylene glycol (Fujifilm Wako Pure Chemical Corporation) Dipropylene glycol (Fujifilm Wako Pure Chemical Corporation) Saturated polybasic acid: Isophthalic acid (Fujifilm Wako Pure Chemical Corporation) Adipic acid (Fujifilm Wako Pure Chemical Corporation)

[0135] [Synthesis Example 1] A four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser was charged with 50 moles of isophthalic acid, 60 moles of diethylene glycol, and 40 moles of dipropylene glycol. The esterification reaction was carried out by heating and stirring the mixture to 210°C under a nitrogen gas stream. When the acid value of the reaction solution fell below 10 KOH mg / g, 50 moles of adipic acid were added, and the esterification reaction was continued to obtain a saturated polyester resin. Subsequently, when the acid value of the reaction solution fell below 10 KOH mg / g, styrene monomer was added to a total of 40% by mass relative to the total of the saturated polyester resin and styrene monomer to obtain a mixture of saturated polyester resin and styrene. The obtained saturated polyester resin had a weight-average molecular weight (Mw) of 10,000. The weight-average molecular weight (Mw) of block (X) of the obtained saturated polyester resin was 4,000.

[0136] [Table 1]

[0137] [Synthesis Examples 2-5] A mixture of saturated polyester resin and styrene was obtained in the same manner as in Synthesis Example 1, except that the composition shown in Table 1 was used. The weight-average molecular weight (Mw) of the saturated polyester resin and the weight-average molecular weight (Mw) of block (X) of the saturated polyester resin are shown in Table 1.

[0138] (B-1) Examples of unsaturated polyester resin synthesis are shown below.

[0139] The following ingredients will be used: Diol: Propylene glycol (Fujifilm Wako Pure Chemical Corporation) Neopentyl glycol (Fujifilm Wako Pure Chemical Corporation) Hydrogenated bisphenol A (Fujifilm Wako Chemical Co., Ltd.) Unsaturated polybasic acids: Maleic anhydride (Fujifilm Wako Pure Chemical Corporation) Fumaric acid (Fujifilm Wako Pure Chemical Corporation) Saturated polybasic acid: Isophthalic acid (Fujifilm Wako Pure Chemical Corporation)

[0140] [Synthesis Example 6] (B-1-1) Synthesis of unsaturated polyester resin A four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser was charged with 100 moles of maleic anhydride, 60 moles of propylene glycol, and 40 moles of neopentyl glycol. The mixture was heated and stirred under a nitrogen gas stream to 210°C to carry out the esterification reaction and obtain an unsaturated polyester resin. Subsequently, styrene monomer was added to the total amount of the unsaturated polyester resin and styrene monomer to 40% by mass, obtaining a mixture of unsaturated polyester resin and styrene. The obtained unsaturated polyester resin had a degree of unsaturation of 100 mol% and a weight-average molecular weight (Mw) of 20,000.

[0141] [Table 2]

[0142] [Synthesis Examples 7-8] (B-1-1) Synthesis of Unsaturated Polyester Resin A mixture of unsaturated polyester resin and styrene was obtained in the same manner as in Synthesis Example 6, except that the composition shown in Table 2 was used. The weight-average molecular weight (Mw) of the unsaturated polyester resin is shown in Table 2.

[0143] [Synthesis Examples 9-11] (B-1-2) Synthesis of Unsaturated Polyester Resin A mixture of unsaturated polyester resin and styrene was obtained in the same manner as in Synthesis Example 6, except that the composition shown in Table 2 was used. The weight-average molecular weight (Mw) of the unsaturated polyester resin is shown in Table 2.

[0144] Other ingredients used include the following:

[0145] (C) Ethylene-unsaturated monomers: • Styrene (Idemitsu Kosan Co., Ltd.)

[0146] (D) Thermal polymerization initiator: • Perhexyl™ I (t-hexyl peroxyisopropyl carbonate, NOF Corporation)

[0147] (E) Glass fiber: • Chopped Strand ECS-03B173 / P9 (Chopped strand glass, fiber diameter 13μm, fiber length 3.0mm, Nippon Electric Glass Co., Ltd.)

[0148] (F) Inorganic filler: • Softon 1200 (calcium carbonate, average particle size 1.80 μm, Bihoku Powdering Industry Co., Ltd.)

[0149] (G) Thickener • Calcium hydroxide (Kishida Chemical Co., Ltd.) Magnesium oxide (Kanto Chemical Co., Ltd.) (H) Other low-shrinkage agents: • PS MS-200 (Polystyrene, Sekisui Chemical Co., Ltd.)

[0150] <Example 1> (Preparation of thermosetting resin compositions) (A) saturated polyester resin and (C) ethylenically unsaturated monomer: 27 parts by mass of a mixture of saturated polyester resin and styrene obtained in Synthesis Example 1 (16 parts by mass of saturated polyester resin, 11 parts by mass of styrene), (B-1-1) unsaturated polyester resin and (C) ethylenically unsaturated monomer: 85 parts by mass of a mixture of unsaturated polyester resin and styrene obtained in Synthesis Example 6 (51 parts by mass of unsaturated polyester resin, 34 parts by mass of styrene), (C) ethylenically unsaturated monomer A thermosetting resin composition was prepared by adding (D) 4 parts by mass of styrene as the main body, (E) 36 parts by mass of chopped strand ECS-03B173 / P9 as glass fiber, (F) 390 parts by mass of Softon 1200 as an inorganic filler, (G) 0.4 parts by mass of calcium hydroxide as a thickener, and (H) 6 parts by mass of polystyrene as an additional low-shrinkage agent to a double-arm kneader and kneading at 30°C for 30 minutes.

[0151] (Liquidity) The fluidity of the thermosetting resin composition immediately after mixing was evaluated by measuring the flow length, i.e., the spiral flow value, using a spiral flow test. Specifically, a spiral flow mold with a trapezoidal cross-sectional shape (top base 6.5 mm, bottom base 8 mm, height 2 mm) was attached to a 50t transfer molding machine, and the spiral flow value (cm) of the thermosetting resin composition was measured under conditions of a charge amount of 50g, a molding temperature of 140°C, and a molding pressure of 5MPa. The results are shown in Tables 3-5.

[0152] (Thin-walled flow test) A thin-walled flow test was conducted using a thermosetting resin composition immediately after mixing. Specifically, a mold with six channels, each 5 mm wide and with thicknesses of 10 μm, 20 μm, 40 μm, 50 μm, 60 μm, or 100 μm, was mounted on a 70t transfer molding machine. The thermosetting resin composition was molded under the conditions of a charge amount of 50 g, a molding temperature of 125°C, a molding pressure of 14 MPa, and a molding time of 4 minutes. The length of the resulting molded product, i.e., the length over which the thermosetting resin composition flowed, was measured. Furthermore, the presence or absence of gas accumulation during the flow process and at the end was visually confirmed. Products with no gas accumulation at any point were classified as "none," and those with gas accumulation at either or both points were classified as "present." The results are shown in Table 3.

[0153] [Table 3]

[0154] As shown in Table 3, for thermosetting resin compositions with a spiral flow value of 110 cm, gas accumulation occurred when the channel thickness was 10 μm. Therefore, it is considered that gas does not escape easily when the channel thickness is 10 μm or less. When the channel thickness was 60 μm or more, the length of the molded product, i.e., the length over which the thermosetting resin composition flowed, was large, at 20 mm or more. Therefore, it is considered that the thermosetting resin composition flows easily when the channel thickness is 60 μm or more. When the channel thickness was 20 μm, 40 μm, or 50 μm, no gas accumulation occurred, and the length of the molded product was less than 10 mm. Therefore, it is considered that when the channel thickness is 15 to 55 μm, gas escapes easily, and the inflow of the thermosetting resin composition is also unlikely to occur.

[0155] (viscosity) The viscosity of the thermosetting resin composition immediately after mixing was evaluated using a flow tester. Specifically, a flow tester viscosity measuring instrument (measuring instrument: CFT-500D, manufactured in 2011, Shimadzu Corporation) was used to measure the flow tester viscosity (Pa·S) of the thermosetting resin composition under the conditions of a heating temperature of 70°C and a load of 7 MPa, using a φ1.5 mm × 10 mm die. The results are shown in Table 4.

[0156] [Table 4-1] [Table 4-2]

[0157] <Examples 2-13, comparative examples 1-3> A thermosetting resin composition was prepared in the same manner as in Preparation Example 1, except that the composition of the raw materials was changed as shown in Table 4. Then, the fluidity and viscosity were evaluated in the same manner as in Preparation Example 1. The results for fluidity are shown in Tables 4 and 5, and the results for viscosity are shown in Table 4.

[0158] <Example 1> (Fabrication of molded stator) A stator was placed in a mold with an air vent thickness of 20 μm, a width of 10 mm, and a channel length of 30 mm. 400 g of the thermosetting resin composition obtained in Fabrication Example 1 was injected, and the molded stator was obtained under the conditions of a molding temperature of 130°C, a molding pressure of 5 MPa, and a molding time of 5 minutes. The filling performance during molding and the presence or absence of burrs, voids, and cracks were evaluated according to the following criteria. The results are shown in Table 5.

[0159] ≪Filling properties during mold stator molding≫ The appearance of mold stators made using the thermosetting resin composition immediately after mixing was visually observed. A condition in which the molded body of the thermosetting resin composition was completely filled without defects along the mold shape was considered good, while a condition with some defects was considered poor.

[0160] <Bulges, voids, and cracks> The appearance of mold stators made using the thermosetting resin composition immediately after mixing was visually inspected, and those without burrs, voids, or cracks were classified as good, while those with these defects were classified as poor.

[0161] (Heat cycle test) A thermosetting resin composition, kneaded and stored at 20°C for 30 days, was used to prepare molded stators using the same method as for the above-mentioned molded stators. A heat cycle test was then performed on these molded stators using a heat cycle tester (tester: TSA-71L-A, manufactured in 2010, ESPEC Corporation), with each cycle consisting of 20 minutes at -40°C and 20 minutes at 140°C in air. The test was performed for 250 cycles, and the appearance of the molded stators was visually inspected every 50 cycles to check for crack formation. Table 5 shows the maximum number of cycles for which no cracks occurred.

[0162] [Table 5-1] [Table 5-2]

[0163] <Examples 2-13, Comparative Examples 1-3> Molded stators were prepared in the same manner as in Example 1, except that the thermosetting resin compositions listed in Table 5 were used. Then, various evaluations were performed in the same manner as in Example 1. Note that heat cycle tests were not performed for Examples 10-13 and Comparative Examples 1-3. The results are shown in Table 5. [Explanation of symbols]

[0164] 10 Upper mold 12 Injection part 14 Lower mold 16 Cavity 18 Air vents 20 mating surface 22 Resin reservoir 30 Convex part 100 molds

Claims

1. A method for manufacturing a molded article, comprising injecting a thermosetting resin composition from the injection section of a mold into a cavity, while exhausting the gas in the cavity through an air vent, and then heating and curing the composition, The temperature of the mold when injecting the thermosetting resin composition is T°C, and the spiral flow value of the thermosetting resin composition at T+10°C is 80 to 120 cm. A method for manufacturing a molded article, wherein the thickness of the air vent is 15 to 55 μm.

2. The thermosetting resin composition is (B) thermosetting resin, (C) Ethylene unsaturated monomers, (D) Thermal polymerization initiator, (E) Glass fiber, and (F) Inorganic filler A method for producing a molded article according to claim 1, comprising the above.

3. The method for producing a molded article according to claim 2, wherein the thermosetting resin composition contains (G) a thickening agent.

4. The method for manufacturing a molded article according to claim 2, wherein the (E) glass fiber is chopped strand glass.

5. The method for manufacturing a molded article according to claim 2, wherein the fiber length of the glass fiber (E) is 6 mm or less.

6. The total amount of the (B) thermosetting resin and the (C) ethylenically unsaturated monomer is 100 parts by mass. (E) glass fibers in 10 to 70 parts by mass, and The inorganic filler (F) is divided into 150 to 600 parts by mass. A method for producing a molded article according to claim 2, comprising:

7. The method for producing a molded article according to claim 2, wherein the average particle size of the inorganic filler (F) is 0.1 to 100 μm.

8. The method for manufacturing a molded article according to any one of claims 1 to 7, wherein the width of the air vent is 5 to 15 mm.

9. The method for manufacturing a molded article according to any one of claims 1 to 7, wherein the injection is performed with the electronic components placed in the cavity.

10. A method for manufacturing a molded article according to any one of claims 1 to 7, wherein the mold is a combination of two or more molds, and the injection section and the air vent are provided in separate molds.

11. The method for manufacturing a molded article according to claim 9, wherein the electronic component is at least one selected from a stator and a rotor.

12. The method for manufacturing a molded article according to claim 9, wherein the mold is installed in a vertical molding machine.

13. The method for producing a molded article according to any one of claims 2 to 7, wherein the thermosetting resin composition contains (A) a saturated polyester resin.

14. The (B) thermosetting resin contains at least (B-1-1) unsaturated polyester resin, The (B-1-1) unsaturated polyester resin is a polycondensate of a diol and an unsaturated polybasic acid. A method for producing a molded article according to any one of claims 2 to 7, wherein the (B-1-1) unsaturated polyester resin contains a structure derived from propylene glycol and a structure derived from neopentyl glycol.

15. The thermosetting resin composition contains (A) a saturated polyester resin, The thermosetting resin composition comprises 100 parts by mass of the total amount of the (B) thermosetting resin and the (C) ethylenically unsaturated monomer. The (A) saturated polyester resin is divided into 5 to 30 parts by mass. The (B) thermosetting resin is 20 to 80 parts by mass, The above (C) ethylenically unsaturated monomer is 80 to 20 parts by mass, The (D) thermal polymerization initiator is 0.5 to 20 parts by mass. The (E) glass fiber is in 10 to 70 parts by mass. The (F) inorganic filler is divided into 150 to 600 parts by mass and The (G) thickener is 0.2 to 9 parts by mass. A method for producing a molded article according to claim 3, which contains the following:

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