Molding composition for injection-molding

Abstract

The present invention relates to a molding material composition capable of injection molding.

Description

Technology Field

[0001] The present invention relates to a molding material composition capable of injection molding. Background Technology

[0002] Resin compositions for molding materials are used as sealing materials to protect semiconductor devices, automotive parts, etc. from the outside, and research to improve the performance of molding materials is continuing in various fields. For example, Japanese Patent Publication No. 2017-197620 relates to an epoxy resin composition for semiconductor sealing comprising an epoxy resin, a phenolic resin curing agent, and a filler, and discloses a technology that improves electrical connection reliability by controlling the content of the filler and the thermal modulus of elasticity of the cured product of the epoxy resin composition.

[0003] Among molding methods, the transfer molding method offers the advantage of stability as it is insensitive to various variables; however, it has the disadvantage of low productivity due to a complex process, such as undergoing a preform process called tableting before the transfer molding operation. On the other hand, injection molding offers superior productivity because it eliminates the tableting process, and it demonstrates excellent productivity and economic efficiency through high accuracy and short cycle times.

[0004] In the case of injection molding, which features a simple manufacturing process and allows for continuous operation, it is crucial that the epoxy molding compound (EMC) reaches the injection machine without clumping when fed into the hopper. In conventional EMC manufacturing processes, small particles are generated using a 3Φ screen and a hammer mill to maintain a smooth pellet appearance, and powder clumping is prevented by setting the process temperature low to 15 to 20°C. However, since injection molding proceeds immediately after raw material input at a relatively high temperature of 25 to 30°C, clumping occurs due to fine particles when applying conventional grinding methods, as well as powder clumping resulting from the use of resins with low softening points. Consequently, clumping occurs within the hopper during injection molding, causing issues with continuous operation.

[0005] Accordingly, there is a need to develop a molding material composition that prevents clumping and offers excellent continuous workability during injection molding. The problem to be solved

[0006] The present invention provides a molding material composition with excellent continuous workability during injection molding by preventing clumping through the control of the fine particle ratio of the molding material composition. means of solving the problem

[0007] The present invention provides a molding material composition for injection molding comprising an epoxy resin, a curing agent, and a filler, wherein the content of particles with a size of 0.5 mm or less is 1 weight% or less, and the specific surface area of ​​the particles is 1.5 to 2.5 m² / g. Effects of the invention

[0008] The present invention provides a molding material composition that prevents powder clumping within the hopper during injection, thereby providing excellent continuous workability. The molding material composition according to the present invention is applicable to injection molding and can simplify the manufacturing process by eliminating the preform process required in conventional transfer molding, and can improve price competitiveness and workability by enabling a continuous process. Since the molding material composition of the present invention exhibits high thermal conductivity due to the use of a thermosetting resin, it can be applied to electric vehicle motors, battery structural materials, etc. Specific details for implementing the invention

[0009] The present invention will be described in detail below. However, it is not limited to the following description, and each component may be modified in various ways or selectively combined as needed. Accordingly, it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0010] As used herein, “viscosity” is measured by conventional methods known in the art, for example, using a Brookfield viscometer at room temperature (25 °C). “Particle size (D 50 )” is measured by conventional methods known in the relevant technical field, and can be measured, for example, by laser light scattering (LLS).

[0011] The molding material composition according to the present invention comprises a thermosetting epoxy resin, a curing agent, and a filler, wherein the particle content is 1 weight% or less and the specific surface area (BET) of the particles is 1.5 to 2.5 m² / g. In the case of a conventional manufacturing process for solid epoxy molding material compositions, small particles are generated using a screen with a mesh (e.g., 3Φ size) and a hammer mill, thereby maintaining a smooth appearance of the pellets and preventing powder clumping by setting the process temperature low to 15 to 20 ℃. However, in the case of injection molding, since injection molding proceeds immediately after raw material input at a relatively high temperature of 25 to 30 ℃, clumping occurs due to fine powder when applying the conventional grinding method and powder clumping occurs due to the use of resins with low softening points. Consequently, clumping occurs within the hopper during injection molding, causing problems with continuous operation. The present invention can improve continuous workability by controlling the fine powder content and specific surface area of ​​the molding material composition, thereby preventing powder clumping after grinding and powder clumping in the hopper during injection.

[0012] The molding material composition of the present invention has a particle content of 1 weight% or less with a size of 0.5 mm or less. If the particle content with a size of 0.5 mm or less exceeds the aforementioned range, powder clumping may occur.

[0013] For example, the molding material composition of the present invention may have a particle content of 0 to 0.2 weight% with a size of 0.1 mm or less, and a particle content of 0 to 1 weight% with a size greater than 0.1 mm and less than or equal to 0.5 mm.

[0014] For example, the molding material composition of the present invention may have a particle content of 0 to 0.2 weight% with a size of 0.1 mm or less, a particle content of 0 to 1 weight% with a size greater than 0.1 mm and 0.5 mm or less, a particle content of 25 to 35 weight% with a size greater than 0.5 mm and 2 mm or less, a particle content of 50 to 70 weight% with a size greater than 2 mm and 4 mm or less, and a particle content of 4 to 20 weight% with a size greater than 4 mm. As the particle size decreases, powder clumping may occur, and if the particle size is excessively large, workability within the barrel may decrease. However, if the particle content by size satisfies the aforementioned ranges, excellent continuous workability can be secured without powder clumping.

[0015] The molding material composition of the present invention has a specific surface area of ​​particles of 1.5 to 2.5 m² / g. If the specific surface area is less than the aforementioned range, the spacing between particles increases, which may cause an increase in injection pressure and poor filling within the mold, thereby reducing workability. As the specific surface area increases, the contact area between particles increases, leading to greater cohesive force, and the electrostatic or van der Waals forces between particles increase, thereby increasing the force to clump together. Therefore, if the specific surface area exceeds the aforementioned range, powder may clump and clog within the hopper during the transfer process in the injection molding machine, which may reduce continuous workability. Additionally, the reduced fluidity may worsen flowability within the hopper, causing the powder to clump or fail to transfer and remain stagnant inside, which may reduce production efficiency.

[0016] The molding material composition of the present invention can be manufactured using a cutter mill. In the manufacture of conventional molding material compositions, hammer mills, jaw crushers, ball mills, vibratory mills, Raymond mills, etc., have been used for crushing and grinding. For example, when grinding with a hammer mill, a strong impact is applied to the material by the hammer, and since the rotational speed of the hammer mill is typically high, even stronger impacts are repeatedly applied, causing random crushing, so the individual particles of the powder form many acute angles. Particles with acute angles increase electrostatic forces or van der Waals forces between particles, which reduces fluidity during injection molding, thereby worsening miscibility within the molding material composition in a plasticized state and potentially lowering moldability when the molding material composition is injected into the equipment. Furthermore, the generation of a large amount of uniform particles within the molding material composition can cause aggregation during the transfer process, which may contaminate the production equipment or reduce moldability.

[0017] On the other hand, in the case of a cutter mill, rotating sharp blades are used, and a smaller impact is applied to the material than that of a hammer, so it can produce relatively large and irregularly shaped particles compared to a hammer mill.

[0018] The molding material composition of the present invention can be manufactured at a grinding speed of 500 to 2,000 RPM. If the grinding speed is below the aforementioned range, the efficiency of the grinding process is reduced, and excessively large particles may be included, which may reduce workability within the barrel; if it exceeds the aforementioned range, the fine powder content may increase, causing powder clumping, and excessive heat generation may cause an overload of the equipment.

[0019] The molding material composition of the present invention can be manufactured by grinding and then screening. The screening can be performed using a mesh with a size of 5 to 7 Ψ. If the mesh size is less than the aforementioned range, the fine powder content increases, which may cause powder clumping; if it exceeds the aforementioned range, excessively large particles may be included, which may reduce workability within the barrel.

[0020] The molding material composition of the present invention comprises an epoxy resin, a curing agent, and a filler. Additionally, the molding material composition of the present invention may further include additives commonly used in such compositions, and non-limiting examples of usable additives include coupling agents, release agents, colorants, catalysts, flame retardants, etc.

[0022] Epoxy resin

[0023] The molding material composition of the present invention comprises an epoxy resin. The epoxy resin is used as the main resin and, by reacting with a curing agent and curing to form a three-dimensional network structure, imparts properties of strong and rigid adhesion to the substrate, as well as heat resistance, chemical resistance, and electrical insulation.

[0024] As the above epoxy resin, an epoxy resin commonly used in the relevant technical field may be used. Non-limiting examples of available epoxy resins include bisphenol A type epoxy resin, alicyclic epoxy resin, cresol novolak type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthalene type epoxy resin, anthracene epoxy resin, tetramethylbiphenyl type epoxy resin, phenol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol S novolak type epoxy resin, biphenyl novolak type epoxy resin, naphthol novolak type epoxy resin, naphthol phenol coaxial novolak type epoxy resin, naphthol cresol coaxial novolak type epoxy resin, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene type epoxy resin, dicyclopentadiene phenol addition type epoxy resin, biphenyl type epoxy resin, phenol aralkyl type epoxy resin, polyfunctional phenol resin, and naphthol. There are aracle-type epoxy resins, etc., and one or more of these may be included.

[0025] For example, the epoxy resin may include a cresol novolak-type epoxy resin, for example, a formaldehyde polymer with (chloromethyl)oxirane and 2-methylphenol (Cas No. 0029690-82-2). In this case, even better heat resistance, chemical resistance, and electrical insulation properties can be secured.

[0026] The above epoxy resin may be used having an epoxy equivalent (EEW) of 100 to 400 g / eq, for example, 180 to 250 g / eq. If the epoxy equivalent is less than the aforementioned range, the curing density may increase, which may result in poor moisture resistance, and if it exceeds the aforementioned range, the curability may be poor.

[0027] The above epoxy resin may have a viscosity (150°C) of 50 to 250 cps, for example, 80 to 150 cps. If the viscosity is below the aforementioned range, excessive bleed flush may occur during molding, and if it exceeds the aforementioned range, flowability may be reduced, resulting in incomplete filling during molding.

[0028] Based on the total weight of the molding material composition of the present invention, the content of the epoxy resin may be 0.5 to 15 weight%, for example, 1 to 10 weight%. If the content of the epoxy resin is less than the aforementioned range, the adhesiveness, flowability, and moldability may be reduced, and if it exceeds the aforementioned range, the reliability of the molding material may be poor due to increased moisture absorption, and the strength may be reduced due to a relative decrease in the filler content.

[0030] hardener

[0031] The molding material composition of the present invention includes a curing agent. The curing agent reacts with the epoxy resin to facilitate the curing of the composition.

[0032] As the curing agent, a curing agent known in the art for curing with an epoxy resin may be used, and the curing agent may be a phenolic compound having two or more phenolic hydroxyl groups within one molecule. Non-limiting examples of usable curing agents include phenol novolak resin, cresol novolak resin, phenol aralkyl resin, polyfunctional phenolic compounds, etc., and may include one or more of these. For example, the curing agent may include a phenol novolak-based curing agent, for example, a phenol polymer with formaldehyde (Cas No. 0009003-35-4).

[0033] The above curing agent may have a viscosity (150°C) of 10 to 200 cps, for example, 20 to 60 cps. If the viscosity is below the aforementioned range, excessive bleed flush may occur during molding, and if it exceeds the aforementioned range, flowability may be reduced, resulting in incomplete filling during molding.

[0034] The above-mentioned curing agent may be one having an electrical conductivity of 35 μS / cm or less. If the electrical conductivity exceeds the aforementioned range, the dielectric constant increases, which may degrade reliability and electrical insulation properties.

[0035] As the above-mentioned curing agent, a hydroxyl group equivalent of 70 to 150 g / eq, for example 85 to 120 g / eq, may be used. If the hydroxyl group equivalent is less than the aforementioned range, the moisture resistance reliability may be inferior, and if it exceeds the aforementioned range, the curability may be inferior.

[0036] Based on the total weight of the molding material composition, the content of the curing agent may be 1 to 20 weight%, for example, 1 to 10 weight%. If the content of the curing agent is less than the aforementioned range, the curability and moldability may be reduced, and if it exceeds the aforementioned range, the reliability of the molding material may be poor and the strength may be reduced due to increased moisture absorption.

[0038] filling

[0039] The molding material composition of the present invention includes a filler. The filler serves to improve the strength, flowability, and thermal conductivity of the molding material composition.

[0040] As the above filler, inorganic fillers commonly used in the relevant technical field may be used without special restrictions. For example, inorganic fillers such as silica, silica nitride, alumina, aluminum nitride, and boron nitride may be used, and these may be used individually or in combination of two or more types.

[0041] The shape of the above-mentioned filler is not particularly limited, and both angular and spherical forms may be used. For example, spherical silica particles, spherical alumina particles, or a mixture thereof may be used.

[0042] The above filler may include two or more types of fillers with different particle sizes. In this case, the moldability and workability of the composition for molding materials can be further improved. For example, the above filler has an average particle size (D 50 A first filler (e.g., silica) having a diameter of 5 to 20 μm, for example 12 to 18 μm, and an average particle size (D 50 It may include a second filler (e.g., alumina) having a length of 20 to 40 μm, for example, 22 to 29 μm.

[0043] Based on the total weight of the molding material composition, the content of the filler may be 10 to 98 weight%, for example, 70 to 98 weight%. If the content of the filler is less than the aforementioned range, the moisture absorption of the cured material may increase, which may reduce the reliability of the molding material, and if it exceeds the aforementioned range, the fluidity may decrease, which may result in poor moldability.

[0045] additives

[0046] The molding material composition of the present invention may additionally include additives commonly used in said compositions. Non-limiting examples of usable additives include coupling agents, release agents, colorants, catalysts, flame retardants, etc.

[0047] Coupling agents promote the bonding between inorganic and organic materials and improve adhesion to the metal substrate; examples include amino silanes and epoxy silanes. Release agents are used to ensure release between the molding material formed after the injection molding composition is cured and the mold; examples include waxes such as paraffin wax, carnauba wax, polyethylene wax, and ester wax; and silicone oils such as silicone oil modified with amines at both ends. Colorants are added to impart color to the molding composition; examples include carbon black and Bengala. Catalysts are used to improve curing speed and workability; examples include imidazole-based catalysts and phosphorus-based catalysts. Flame retardants are used to impart flame retardancy; examples include metal hydroxides.

[0048] The above additives may be added within a content range known in the relevant technical field, and for example, may be included in an amount of 0.01 to 10 weight% each with respect to the total weight of the molding material composition, but are not limited thereto.

[0050] The molding material composition according to the present invention can be manufactured by a melt mixing method using conventional methods known in the art, such as a Banbury mixer, a kneader, a roll, a single-screw or twin-screw extruder, and a conid. The molding material composition of the present invention is manufactured in a solid form, such as a powder or granule, and can be melted and molded using an injection molding machine. For example, in the case of the solid form molding material composition of the present invention, after uniformly mixing each component as described above, the mixture is melt-mixed at a temperature of 80 to 130°C using a heat kneader, cooled to room temperature, then ground into a powder state using a cutter mill at a grinding speed of 500 to 2,000 RPM, and then sieved through a screen with a size of 5 to 7 Ψ to produce a solid form.

[0052] The present invention will be explained in more detail below through examples. However, the following examples are intended only to aid in understanding the present invention and do not imply that the scope of the present invention is limited to these examples in any way.

[0054] [Experimental Example 1-24]

[0055] After mixing each component according to the composition listed in Table 1-4 below, the mixture was melt-mixed at a temperature of 115°C using a kneader, cooled to room temperature, and then ground and screened according to the process conditions of Table 1-4 below to prepare the molding material composition of each experimental example.

[0056] After separating the particles of each experimental example using 140 Mesh (0.1 mm), 35 Mesh (0.5 mm), 10 Mesh (2 mm), and 5 Mesh (4 mm) frames, the particle content for each particle size range was measured by comparing the input amount of particles, the amount of particles that passed through the mesh, and the amount of particles remaining on the mesh. In addition, the specific surface area of ​​the particles of each experimental example was measured using the BET method with an ASAP 2020 instrument (Micromeritics). The measurement results are listed in Table 1-4 below.

[0058]

[0059]

[0060]

[0061]

[0062] Epoxy resin: Formaldehyde polymer with (chloromethyl)oxirane and 2-methylphenol (Cas. No. 0029690-82-2, epoxy equivalent 200 g / eq)

[0063] Hardener: Phenol polymer with formaldehyde (Cas. No. 0009003-35-4, OH equivalent 103 g / eq)

[0064] Filler: Silica (D 50 15 µm) and alumina (D 50 A mixture of (25.3 μm) (mixing ratio = 1 : 15.9 by weight)

[0065] Silane: Trimethoxy[3-(phenylamino)propyl]silane

[0066] Release Agent 1: Ester wax

[0067] Release Agent 2: Biterminal amine-modified silicone oil

[0068] Coloring agent: Carbon black

[0069] Catalyst: Mixture of 2-phenyl-4-methyl-5-hydroxymethylimidazole and THDN-TPP (Tetraphenylphosphonium, TetrahydroxyDinaphthalene) (mixing ratio = 1:1 by weight)

[0070] Flame retardant: Magnesium hydroxide

[0072] [Physical Property Evaluation]

[0073] The physical properties of the molding material compositions prepared in each experimental example were measured as follows, and the results are shown in Table 5-8 below.

[0075] Powder clumping after grinding

[0076] After leaving the ground powder of each experimental example at 30°C for 1 hour, the presence of powder clumping was observed visually.

[0077] [metewand]

[0078] Good: No powder clumping

[0079] NG: Powder clumping occurs

[0081] Powder clumping in the hopper

[0082] After feeding the powder of each experimental example into the injection molding machine hopper, the presence of clumping was visually observed during the continuous manufacturing process as it moved into the barrel.

[0083] [metewand]

[0084] Good: No cake phenomenon (rathole) or bridging phenomenon in the ingredients

[0085] NG: Occurrence of cake phenomenon (rathole) or bridging phenomenon in the ingredients

[0087] Injection molding continuous workability

[0088] The powder of each experimental example was fed into an injection molding facility, and after performing continuous operation for 1 hour, the condition of the nozzle and gate was observed to evaluate the continuous operation capability of the injection molding.

[0089] [metewand]

[0090] Good: No nozzle or gate clogging

[0091] NG: Nozzle and gate clogging occurred

[0093]

[0094]

[0095]

[0096]

[0097] As shown in Tables 5-8 above, in the case of the molding material compositions of Experimental Examples 1 to 15 according to the present invention, it can be confirmed that powder clumping after grinding, powder clumping in the hopper during injection, and continuous injection molding workability are improved. On the other hand, in the case of the molding material compositions of Experimental Examples 16-24, in which the particle content and / or specific surface area of ​​particles with a size of 0.5 mm or less falls outside the scope of the present invention, powder clumping occurred in the hopper after grinding and during injection, and continuous injection molding workability was found to be inferior.

Claims

Claim 1 A molding material composition for injection molding comprising an epoxy resin, a curing agent, and a filler, wherein the content of particles with a size of 0.1 mm or less is 0 to 0.2 weight%, the content of particles with a size greater than 0.1 mm and 0.5 mm or less is 0 to 1 weight%, the content of particles with a size greater than 0.5 mm and 2 mm or less is 25 to 35 weight%, the content of particles with a size greater than 2 mm and 4 mm or less is 50 to 70 weight%, the content of particles with a size greater than 4 mm is 4 to 20 weight%, the total content of the particles with a size of 0.1 mm or less and the particles with a size greater than 0.1 mm and 0.5 mm or less is 1 weight% or less, and the specific surface area of ​​the particles is 1.5 to 2.5 m² / g. Claim 2 delete Claim 3 delete Claim 4 A molding material composition for injection molding according to claim 1, manufactured by grinding using a cutter mill at a grinding speed of 500 to 2,000 RPM and then sieving with a screen of size 5 to 7 φ. Claim 5 A molding material composition for injection molding according to claim 1, wherein the epoxy equivalent (EEW) of the epoxy resin is 100 to 400 g / eq, the viscosity (150 ℃) is 50 to 250 cps, the viscosity (150 ℃) of the curing agent is 10 to 200 cps, the electrical conductivity is 35 μS / cm or less, and the hydroxyl equivalent is 70 to 150 g / eq. Claim 6 In claim 1, an injection molding molding composition comprising, based on the total weight of the molding composition, 0.5 to 15 weight% of the epoxy resin, 1 to 20 weight% of the curing agent, and 10 to 98 weight% of the filler.

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