Method for producing resin material for transfer molding and method for producing resin molded body

Abstract

Provided is a method for producing a resin material for transfer molding or a resin molded article, in which noise generation during kneading of resin raw materials is reduced. [Solution] A method for producing a resin material for transfer molding using an extruder, the method comprising the steps of: preparing a powder of an epoxy resin composition; classifying the powder of the epoxy resin composition and removing fine powder that passes through an 80 mesh so that the fine powder accounts for 7 mass% or less of the total powder of the epoxy resin composition, thereby obtaining a classified powder of the epoxy resin composition; supplying the classified powder of the epoxy resin composition into the cylinder via the hopper and heating the classified powder of the epoxy resin composition in the cylinder to obtain a melt; extruding the melt from the die, which has a predetermined opening shape, using the screw; and cutting the melt extruded from the die to a predetermined length, thereby obtaining a resin material for transfer molding.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin material for transfer molding and a method for producing a resin molded article, and more particularly to a method for producing a resin tablet for transfer molding by extrusion molding and a method for producing a resin molded article by injection molding. [Background technology]

[0002] Conventionally, thermosetting resin compositions have been widely used in the fields of electricity and electronics, such as casting, sealing, and laminates, as well as in the fields of pressure-sensitive adhesives, paints, composite materials, etc. More specifically, thermosetting resin compositions are suitably used as casting materials or as sealing materials for sealing electronic devices.

[0003] In general, a resin material provided as a casting material or a sealing material is processed into a desired shape by, for example, a step of supplying resin raw materials (raw material supply step), a step of heating, melting, and mixing the raw materials (kneading step), and a step of molding the kneaded resin composition (molding step). The kneading step when processing a thermosetting resin composition into a desired shape is generally carried out by kneading raw materials supplied through a hopper in a kneader equipped with a screw.

[0004] For example, in the case of resin compositions that contain a large amount of polyethylene terephthalate (hereinafter sometimes referred to as PET), a polyester resin, the raw materials supplied to the kneader often stick to the screw inside the cylinder or fuse together, causing poor biting and abnormal noises such as friction, making handling an issue.

[0005] As a solution to the problem of abnormal noises occurring during kneading, a method of blending silicone oil into a resin composition has been disclosed (for example, Patent Document 1). Patent Document 1 proposes a method of controlling abnormal noises generated in a kneader by incorporating 0.1% by mass or more and 5% by mass or less of silicone into a resin composition containing polyester resin, polycarbonate resin, PE resin, rubber material, or the like, and kneading the resulting composition. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 6-228417 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional methods, when the resin raw materials are kneaded using a kneader, unpleasant noises or sounds may be generated, which may deteriorate the working environment.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a method for producing a resin material for transfer molding or a resin molded article in which the generation of abnormal noise during kneading of the resin raw materials is reduced. [Means for solving the problem]

[0009] In view of the above circumstances, the inventors have conducted extensive research and discovered that the abnormal noise generated during kneading can be reduced by adjusting the particle size of the granular raw material supplied to the kneader, and have completed the present invention. According to the present invention, there is provided a method for producing a resin material for transfer molding or a method for producing a resin molded article, as shown below. [1] A method for producing a resin material for transfer molding using an extruder that includes a cylinder, a screw inserted into the cylinder, a die having a predetermined opening shape provided on the injection side of the cylinder, and a hopper that supplies raw material to the cylinder, The method comprises: preparing a powder of an epoxy resin composition; a step of classifying the powder of the epoxy resin composition and removing fine powder passing through an 80 mesh so that the amount of the fine powder is 7% by mass or less based on the total amount of the powder of the epoxy resin composition, thereby obtaining a classified powder of the epoxy resin composition; supplying the classified powder of the epoxy resin composition into the cylinder through the hopper, and heating the classified powder of the epoxy resin composition in the cylinder to obtain a molten product; a step of extruding the molten material through the die having a predetermined opening shape by rotating the screw; and cutting the molten material extruded from the die to a predetermined length to obtain a resin material for transfer molding. [2] The method according to [1], The method wherein the transfer molding resin material is in tablet form. [3] A method for producing a resin molded product using an injection molding machine comprising a cylinder, a screw inserted into the cylinder, and a hopper for supplying raw material to the cylinder, comprising: The method comprises: preparing a powder of an epoxy resin composition; a step of classifying the powder of the epoxy resin composition and removing fine powder passing through an 80 mesh so that the amount of the fine powder is 7% by mass or less based on the total amount of the powder of the epoxy resin composition, thereby obtaining a classified powder of the epoxy resin composition; supplying the classified powder of the epoxy resin composition into the cylinder through the hopper, and heating the classified powder of the epoxy resin composition in the cylinder to obtain a molten product; Injecting the molten material from the cylinder into a mold by rotating the screw; A method comprising: [Effects of the Invention]

[0010] According to the present invention, there is provided a method for producing a resin material for transfer molding or a resin molded article, in which the generation of abnormal noise during material kneading is reduced. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a longitudinal cross-sectional view of an extruder according to an example of the present embodiment. [Figure 2] 1 is a vertical cross-sectional view of an injection molding machine according to an example of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and their description will be omitted where appropriate. Furthermore, all drawings are for illustrative purposes only. The shapes and dimensional ratios of each component in the drawings do not necessarily correspond to actual products. In this specification, the expression "a to b" in the description of a numerical range means "a or more and b or less" unless otherwise specified. For example, "5 to 90%" means "5% or more and 90% or less."

[0013] [First embodiment] A first embodiment of the present invention relates to a method for producing a resin material for transfer molding. A method for producing a resin material for transfer molding according to a first embodiment of the present invention is carried out using an extruder equipped with a cylinder, a screw inserted into the cylinder, a die having a predetermined opening shape provided on the injection side of the cylinder, and a hopper for supplying raw material to the cylinder. The method of this embodiment includes the following steps. Step 1: Prepare a powder of the epoxy resin composition. Step 2: The powder of the epoxy resin composition obtained in step 1 is classified, and fine powder that passes through an 80 mesh is removed so that the amount of the fine powder is 7% by mass or less of the total powder of the epoxy resin composition, thereby obtaining a classified powder of the epoxy resin composition. Step 3: The classified powder of the epoxy resin composition obtained in step 2 is fed into the cylinder through the hopper, and the classified powder of the epoxy resin composition is heated and kneaded in the cylinder to obtain a molten product. Step 4: The melt obtained in step 3 is extruded through a die having a predetermined opening shape by the rotation of the screw. Step 5: The molten material extruded from the die in step 4 is cut to a predetermined length to obtain a resin material for transfer molding. Each step will be described in detail below.

[0014] The preparation of the epoxy resin composition powder in step 1 is carried out using means known in the art. For example, the epoxy resin composition powder can be produced by uniformly mixing the components contained in the resin composition using a mixer or the like, then melt-kneading the mixture using a kneading machine such as a roll, kneader, or extruder, and then cooling and pulverizing the mixture. In this embodiment, the components contained in the resin composition are an epoxy resin, a phenolic resin-based curing agent, an inorganic filler, and a curing accelerator, and wax, a coupling agent, a colorant, a stress-reducing agent, and the like may also be used as necessary.

[0015] In step 1, the particle size and particle size characteristics of the epoxy resin composition powder are not particularly limited, but from the viewpoint of ease of handling, the powder preferably has a particle size of 100 μm to 10 mm, and more preferably has a particle size in the range of 100 μm to 5 mm.

[0016] In step 2, the epoxy resin composition powder obtained in step 1 is classified to adjust the particle size. Specifically, fine powder that passes through an 80-mesh sieve (material that falls under the 80-mesh sieve) is removed from the epoxy resin composition powder obtained in step 1 so that the amount of the fine powder is 7% by mass or less relative to the total amount of the epoxy resin composition powder, thereby obtaining a classified powder of the epoxy resin composition. The amount of fine powder that passes through an 80-mesh sieve (180 μm opening) (material that falls under the 80-mesh sieve) relative to the total amount of the epoxy resin composition powder is preferably 6% by mass or less, and more preferably 5% by mass or less. By adjusting the amount of fine powder passing through an 80-mesh sieve contained in the classified powder of the epoxy resin composition to fall within the above range, it is possible to reduce the generation of abnormal noise when the classified powder is heated and kneaded using an extruder in the next step 3.

[0017] In the subsequent step 3, the classified powder of the epoxy resin composition obtained in step 2 is supplied into the cylinder of an extruder via a hopper, and the classified powder of the epoxy resin composition is heated and kneaded in the cylinder to obtain a molten product. Step 3 is performed using an extruder (extrusion molding machine). A longitudinal cross-sectional view of an extruder 100 used in the method of this embodiment is shown in FIG. 1. The extruder 100 has a hopper 2 into which the classified powder 1 of the epoxy resin composition is introduced, and a temperature-controlled die 5 attached to the tip (injection end) of the extruder, which has an opening of the same shape as the predetermined tablet cross-section. The extruder 100 is further equipped with a heater 41 for heating the raw material powder via a cylinder 43. A screw 42 is incorporated within the cylinder 43 and the input cylinder 43a to extrude the classified powder 1 of the epoxy resin composition and knead the heated, molten epoxy resin composition 1 while extruding it. A temperature regulator 51 is also connected to the extruder to control the temperature of the die 5.

[0018] The classified powder 1 of the epoxy resin composition is fed from a hopper 2 into a cylinder 43 of an extruder, and is plasticized into a molten state by heating with a heater 41 and kneading by the rotation of a screw 42 provided in the cylinder 43. In step 4, this plasticized epoxy resin composition 1 is continuously extruded from the opening of a die 5 to form an extruded material 6.

[0019] Next, in step 5, the extruded material 6 extruded from the extruder in step 4 is cut into a predetermined tablet length by a cutter (not shown), and the resin material for transfer molding is obtained as a tablet.

[0020] In this embodiment, the opening shape of the die 5 attached to the tip of the extruder is the same as the cross-sectional shape of the target epoxy resin composition tablet. When the opening shape is circular, the dimensions of the opening shape are, for example, 15 mm or more and 100 mm or less in diameter, and preferably 20 mm or more and 80 mm or less. The opening shape, including its dimensions, is appropriately selected according to the target tablet shape.

[0021] In this embodiment, the extruded material 6 extruded from the extruder is cut to a desired length by a cutter. This length is, for example, in the range of 15 mm to 300 mm, and preferably 20 mm to 200 mm. Tablet-shaped epoxy resin compositions having dimensions within the above range are preferred because they have excellent melting properties in the subsequent transfer molding.

[0022] In steps 3 to 5, the operating conditions of the extruder are appropriately selected depending on the shape, size, composition, and application of the desired tablets. For example, the screw rotation speed when extruding the molten epoxy resin composition is preferably 15 to 35 rpm, more preferably 20 to 30 rpm. Furthermore, the conditions for extruding the molten epoxy resin composition are preferably a temperature of 80 to 100°C and a pressure of 10 to 30 bar.

[0023] The die temperature is preferably controlled by a temperature regulator 51 at 80 to 100°C, more preferably in the range of 85 to 90°C. The die temperature setting can be adjusted so that the diameter of the extruded tablet satisfies the allowable value and the tablet has a smooth appearance.

[0024] The transfer molding resin material obtained through the above steps 1 to 5 is transferred to a transfer molding machine (not shown) and used to encapsulate an object to be encapsulated, such as an electronic component, etc. Examples of the object to be encapsulated include, but are not limited to, a circuit board on which electronic components are mounted, a rotor core to which a magnet is fixed, a stator core to which a coil or the like is insulated, an on-vehicle electronic control unit, etc.

[0025] [Second embodiment] The second embodiment of the present invention relates to a method for producing a resin molded article. A method for producing a resin molded product according to a second embodiment of the present invention is carried out using an injection molding machine comprising a cylinder, a screw inserted into the cylinder, a hopper for supplying raw material to the cylinder, and a mold directly connected to the injection gate of the cylinder. The method of this embodiment includes the following steps. Step 1: Prepare a powder of the epoxy resin composition. Step 2: The powder of the epoxy resin composition obtained in step 1 is classified, and fine powder that passes through an 80 mesh is removed so that the amount of the fine powder is 7% by mass or less of the total powder of the epoxy resin composition, thereby obtaining a classified powder of the epoxy resin composition. Step 3: The classified powder of the epoxy resin composition obtained in step 2 is fed into the cylinder through the hopper, and the classified powder of the epoxy resin composition is heated and kneaded in the cylinder to obtain a molten product. Step 4: The melt obtained in step 3 is extruded by the rotation of the screw into a mold directly connected to the injection side gate of the cylinder. Step 5: After heating and molding in the mold, the molded product is removed from the mold. Each step will be described in detail below.

[0026] The preparation of the epoxy resin composition powder in step 1 is carried out using means known in the art. For example, the epoxy resin composition powder can be produced by uniformly mixing the components contained in the resin composition using a mixer or the like, then melt-kneading the mixture using a kneading machine such as a roll, kneader, or extruder, and then cooling and pulverizing the mixture. In this embodiment, the components contained in the resin composition are an epoxy resin, a phenolic resin-based curing agent, an inorganic filler, and a curing accelerator, and wax, a coupling agent, a colorant, a stress-reducing agent, and the like may also be used as necessary.

[0027] In step 1, the particle size and particle size characteristics of the epoxy resin composition powder are not particularly limited, but from the viewpoint of ease of handling, the powder preferably has a particle size of 100 μm to 10 mm, and more preferably has a particle size in the range of 100 μm to 5 mm.

[0028] In step 2, the epoxy resin composition powder obtained in step 1 is classified to adjust the particle size. Specifically, fine powder that passes through an 80-mesh sieve (material that falls under the 80-mesh sieve) is removed from the epoxy resin composition powder obtained in step 1 so that the amount of the fine powder is 7% by mass or less relative to the total amount of the epoxy resin composition powder, thereby obtaining a classified powder of the epoxy resin composition. The amount of fine powder that passes through an 80-mesh sieve (180 μm opening) (material that falls under the 80-mesh sieve) relative to the total amount of the epoxy resin composition powder is preferably 6% by mass or less, and more preferably 5% by mass or less. By adjusting the amount of fine powder passing through an 80-mesh sieve contained in the classified powder of the epoxy resin composition to fall within the above range, it is possible to reduce the generation of abnormal noise when the classified powder is heated and kneaded using an injection molding machine in the next step 3.

[0029] In the subsequent step 3, the classified powder of the epoxy resin composition obtained in step 2 is fed into the cylinder of an injection molding machine via a hopper, and the classified powder of the epoxy resin composition is heated and kneaded in the cylinder to obtain a molten product. Step 3 is carried out using an injection molding machine. FIG. 2 shows a longitudinal cross-sectional view of the injection molding machine used in the method of this embodiment. The injection molding machine has a hopper 2 into which the classified powder of the epoxy resin composition is introduced, and a mold 15 directly connected to the tip (injection end) of the injection molding machine. The injection molding machine is also equipped with a heater (not shown) for heating the raw material powder via a cylinder 43, and a screw 42 is incorporated into cylinder 43 and the cylinder on the introduction side to extrude the classified powder of the epoxy resin composition and knead the heated, molten epoxy resin composition while extruding it.

[0030] The classified powder of the epoxy resin composition is fed from the hopper 2 into the cylinder 43 of the injection molding machine, and is plasticized into a molten state by heating with a heater and kneading with the rotation of the screw 42 provided in the cylinder 43. In step 4, the plasticized epoxy resin composition is continuously extruded into the mold from the injection gate of the injection molding machine as the screw 42 advances. After the piston portion 16 and the sleeve portion 17 are fitted together, sufficient holding pressure can be applied.

[0031] In steps 3 and 4, the operating conditions of the injection molding machine are appropriately selected. For example, the screw rotation speed when extruding the molten epoxy resin composition into the mold is preferably 15 to 35 rpm, more preferably 20 to 30 rpm. Furthermore, the conditions for extruding the molten epoxy resin composition into the mold are preferably a temperature of 80 to 100°C and a pressure of 10 to 30 bar.

[0032] Next, in step 5, the molten resin 6 extruded from the cylinder 43a of the injection molding machine in step 4 is injected into a mold having a predetermined shape and cured and molded within the mold. The obtained resin molded body is removed from the mold.

[0033] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted. [Example]

[0034] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these. The components used in the examples are listed below.

[0035] (epoxy resin) Epoxy resin 1: Orthocresol novolac epoxy resin (EPICLON N-670, manufactured by DIC Corporation) (hardening agent) Hardener 1: Novolac phenolic resin (PR-53195, manufactured by Sumitomo Bakelite Co., Ltd., hydroxyl equivalent: 104 g / eq) (curing catalyst) Curing catalyst 1: 2-phenyl-4,5-dihydroxymethylimidazole represented by the following formula (1) (melting point 225 to 235°C, molecular weight 204, active temperature range 155 to 175°C, (2PHZ-PW, manufactured by Shikoku Chemical Industries, Ltd., fine powder)) [ka]

[0036] (Inorganic filler) Inorganic filler 1: Glass fiber (CS3E479, manufactured by Nittobo Co., Ltd.) Inorganic filler 2: crushed silica (RD-8, manufactured by Tatsumori Co., Ltd., average particle size D 50 =15μm) Inorganic filler 3: crushed silica (F-207, manufactured by Fumitec Co., Ltd., average particle size D 50 =7μm) (low stress agent) Low-stress agent 1: Silicone rubber (CF2152, manufactured by Dow Corning Toray Co., Ltd.) (mold release agent) Release agent 1: Calcium stearate (Tokyo Chemical Industry Co., Ltd.) (coloring agent) Colorant 1: Carbon black (#5, manufactured by Mitsubishi Chemical Corporation)

[0037] [Preparation of Epoxy Resin Composition] (Preparation Example 1) First, the components were premixed for 20 minutes in a Henschel mixer (volume 200 liters, rotation speed 900 rpm) set at room temperature according to the formulation shown in Table 1. The resulting mixture was then pulverized using a continuous rotary ball mill (Dynamic Mill MYD25 manufactured by Nippon Coke Engineering Co., Ltd., screw rotation speed 500 rpm, alumina ball diameter 10 mm, ball volume filling rate relative to the device capacity 50%) at a material feed rate of 200 kg / hr while maintaining the material temperature at 30°C or below. Next, the resin composition obtained by pulverization was sieved using a sieve with 180 μm openings to remove fine powder, thereby obtaining a sieved granular resin composition (resin composition 1). Using 40 g of this sieved resin composition as a sample, the amount of fine powder having a particle size of 180 μm or less was confirmed by passing the sample through a JIS standard sieve with 180 μm openings attached to a low-tap sieve vibrator while vibrating the sieve (hammer blows: 120 times / min) for 20 minutes to classify the sample. The amount of fine powder having a particle size of 180 μm or less was found to be 0.5% by mass.

[0038] (Preparation Example 2) Resin composition 2 was obtained by adding back some of the material that passed through the 180 μm mesh sieve to resin composition 1 obtained in Example 1 to adjust the amount of fine powder having a particle size of 180 μm or less to 4.0 mass %.

[0039] (Preparation Example 3) Resin composition 3 was obtained by adding back some of the material that passed through the 180 μm mesh sieve to resin composition 1 obtained in Example 1 so that the amount of fine powder with a particle size of 180 μm or less was 8.0 mass%.

[0040] [Evaluation of abnormal noise when kneading epoxy resin composition powder] (Examples 1 and 2, Comparative Example 1) 2 kg of powder of Resin Compositions 1 to 3 obtained in Preparation Examples 1 to 3, respectively, was charged into an extruder (SANTROL-3500, screw diameter φ50 mm) manufactured by Yamashiro Seiki Co., Ltd., and kneaded at a nozzle temperature of 70°C / 45°C, a rotation speed of 30 rpm, and a back pressure of 3.5 MPa. The sound volume generated during kneading was measured using a digital sound level meter (model number 78588) manufactured by Shinwa Co., Ltd. The results are shown in Table 1. It is preferable that the noise generated during kneading using an extruder be as low as possible when measured with a sound level meter; if it is less than 70 dB, it can be considered that there is an effect of reducing noise, and if it is 70 dB or more, it is considered that there is noise.

[0041] (Examples 3 to 4, Comparative Example 2) 2 kg of powder of Resin Compositions 1 to 3 obtained in Preparation Examples 1 to 3, respectively, was placed in a 100-ton injection molding machine (EC100NR, screw diameter φ32 mm) manufactured by Toshiba Machine Co., Ltd., and kneaded at nozzle temperatures of 85°C / 65°C / 45°C, a rotation speed of 40 rpm, and a back pressure of 5 MPa. The sound volume generated during kneading was measured using a digital sound level meter (model number 78588) manufactured by Shinwa Co., Ltd. The results are shown in Table 1. It is preferable that the noise generated during kneading using an injection molding machine be as low as possible when measured with a sound level meter. If the noise level is less than 80 dB, it can be considered that there is an effect of reducing noise, and if it is 80 dB or higher, it is considered that noise is present.

[0042] [Table 1] [Explanation of symbols]

[0043] 100 Extruder 1. Epoxy resin composition powder 2 Hopper 5. Soybeans 6 Extrusions 41 Heater 42 Screw 43 cylinders 43a Input cylinder 51 Temperature controller 15 Molds 16 Piston part 17 Sleeve part

Claims

1. A method for producing a resin material for transfer molding using an extruder including a cylinder, a screw inserted into the cylinder, a die provided on the injection side of the cylinder and having a predetermined opening shape, and a hopper for supplying raw material to the cylinder, comprising: The method comprises: preparing a powder of an epoxy resin composition; a step of classifying the powder of the epoxy resin composition and removing fine powder passing through an 80 mesh so that the amount of the fine powder is 7% by mass or less based on the total amount of the powder of the epoxy resin composition, thereby obtaining a classified powder of the epoxy resin composition; supplying the classified powder of the epoxy resin composition into the cylinder through the hopper, and heating the classified powder of the epoxy resin composition in the cylinder to obtain a molten product; a step of extruding the molten material through the die having a predetermined opening shape by rotating the screw; and cutting the molten material extruded from the die to a predetermined length to obtain a resin material for transfer molding.

2. 10. The method of claim 1, The method wherein the transfer molding resin material is in tablet form.

3. A method for producing a resin molded product using an injection molding machine including a cylinder, a screw inserted into the cylinder, and a hopper for supplying raw material to the cylinder, comprising: The method comprises: preparing a powder of an epoxy resin composition; a step of classifying the powder of the epoxy resin composition and removing fine powder passing through an 80 mesh so that the amount of the fine powder is 7% by mass or less based on the total amount of the powder of the epoxy resin composition, thereby obtaining a classified powder of the epoxy resin composition; supplying the classified powder of the epoxy resin composition into the cylinder through the hopper, and heating the classified powder of the epoxy resin composition in the cylinder to obtain a molten product; Injecting the molten material from the cylinder into a mold by rotating the screw; A method comprising:

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