Resin composition for injection molding and method for injection-molding said composition

Abstract

A resin composition for injection molding according to the present invention comprises (A) a thermosetting resin, (B) a curing agent, (C) an inorganic filler, and (D) a curing accelerator. When a thermomechanical analysis (TMA) is performed, the glass transition temperature of the resin composition for injection molding as measured at a temperature increase rate of 10 °C / min is 160-220°C, and the reduction rate of spiral flow after the resin composition for injection molding is stored for 7 days at 30°C is 17% or less.

Description

Resin composition for injection molding and method for injection molding said composition

[0001] The present invention relates to a resin composition for injection molding and a method for injection molding the composition. The present invention relates to a resin composition for injection molding and a method for injection molding the composition. The present invention relates to a resin composition for injection molding and a method for injection molding the composition. The present invention relates to a resin composition for injection molding and a method for injection molding the composition.

[0002] Patent Document 1 discloses an epoxy resin composition containing, as essential components, an epoxy resin, a phenolic compound curing agent, a curing accelerator, and an inorganic filler. The document also describes that the epoxy resin composition may contain wax.

[0003] Patent Document 2 discloses an epoxy resin injection molding material that contains only a multifunctional epoxy resin, a bifunctional epoxy resin, an epoxy resin curing agent, a curing accelerator, an inorganic filler, a silane coupling agent, and a mold release agent, is solid at room temperature, and satisfies predetermined physical properties. Carnauba wax is described as the mold release agent. The document also describes that the epoxy resin injection molding material has excellent moldability.

[0004] Japanese Patent Laid-Open No. 8-67741 Japanese Patent Laid-Open No. 2013-127042

[0005] However, the resin compositions for injection molding described in Patent Documents 1 and 2 tend to harden during the heat treatment in injection molding, resulting in poor kneading and clogging of the sprue of the mold, which can lead to molding defects during injection molding and reduced manufacturing stability.

[0006] The present inventors have found that when a resin composition satisfies certain conditions, the balance between thermal stability and curability in injection molding is improved, thereby solving the above-mentioned problems, and have completed the present invention. That is, the present invention can be described as follows.

[0007] [1] A resin composition for injection molding comprising (A) a thermosetting resin, (B) a curing agent, (C) an inorganic filler, and (D) a curing accelerator, wherein the glass transition temperature of the resin composition for injection molding is 160°C or higher and 220°C or lower, as measured by thermomechanical analysis (TMA) at a heating rate of 10°C / min, and the spiral flow loss after storage at 30°C for 7 days is 17% or lower. [2] The resin composition for injection molding according to [1], wherein, when the torque value is measured over time using a Labo Plastomill at a rotation speed of 30 rpm and a measurement temperature of 130°C, the minimum torque value a is 3.3 N m or lower, and when the torque value is measured over time at a rotation speed of 30 rpm and a measurement temperature of 150°C, the minimum torque value b is 1.2 N m or lower. [3] The injection-molding resin composition according to [1] or [2], wherein, when the torque value is measured over time using a Labo Plastomill at a rotation speed of 30 rpm and a measurement temperature of 130°C, the time T1 during which the torque value is equal to or less than twice the minimum torque value a is 60 seconds or more and 200 seconds or less, and when the torque value is measured over time at a rotation speed of 30 rpm and a measurement temperature of 150°C, the time T1' during which the torque value is equal to or less than twice the minimum torque value b is 35 seconds or more and 100 seconds or less. [4] The injection-molding resin composition according to any one of [1] to [3], wherein the curing accelerator (D) includes a phosphorus-based curing accelerator and an imidazole-based curing accelerator. [5] The injection-molding resin composition according to [4], wherein the phosphorus-based curing accelerator is at least one selected from the group consisting of an organic phosphine, a tetra-substituted phosphonium compound, and a phosphobetaine compound.[6] The resin composition for injection molding according to [5], wherein the organic phosphine is tris(4-methylphenyl)phosphine or tris(4-methoxyphenyl)phosphine; the tetra-substituted phosphonium compound is tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrakis(4-methylphenyl)borate, tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate, a molecular compound of tetraphenylphosphonium and a bisphenol, or a complex salt of tetraphenylphosphonium and a dihydroxynaphthalene; and the phosphobetaine compound is 2-(triphenylphosphonium)phenolate, 4-hydroxy-2-(triphenylphosphonium)phenolate, 3-(triphenylphosphonium)phenolate, or an adduct of triphenylphosphine and 1,4-benzoquinone. [7] The resin composition for injection molding according to [4], wherein the imidazole curing accelerator is at least one selected from 2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-benzyl-2-phenylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 2-phenyl-1H-imidazole-4,5-dimethanol, and 2-phenyl-4,5-dihydroxymethylimidazole. [8] The resin composition for injection molding according to any one of [1] to [7], wherein the thermosetting resin (A) has a softening point of 110°C or lower. [9] The resin composition for injection molding according to any one of [1] to [8], further comprising a mold release agent (E).

[10] The resin composition for injection molding according to any one of [1] to [9], wherein in a DSC curve obtained by using a differential scanning calorimeter to raise the temperature from 30°C to 330°C at a heating rate of 10°C / min, the peak temperature of the maximum exothermic peak is 135°C or higher and lower than 175°C, and the full width at half maximum of the maximum exothermic peak, determined using a straight line connecting the point at which the heat flow rate is minimum before the maximum exothermic peak and the point at which the heat flow rate is minimum after the maximum exothermic peak, as a baseline, is 32°C or lower.

[11] A resin composition for injection molding used in an injection molding apparatus comprising: an injection unit comprising a cylinder, a screw inserted into the cylinder, and a nozzle through which a melt of a resin composition for injection molding melt-kneaded in the cylinder by the screw is injected; and a mold comprising a sprue serving as a passage for the injected melt, and a cavity into which the melt is filled via the sprue, wherein the temperature inside the cylinder is from room temperature (25°C) to 140°C, the temperature inside the nozzle is from 100°C to 140°C, and the temperature inside the cavity is from 120°C to 180°C. The resin composition for injection molding according to any one of [1] to

[10] .

[12] An injection molding method using an injection molding apparatus comprising: an injection unit including a cylinder, a screw inserted into the cylinder, and a nozzle through which a melt melted and kneaded by the screw in the cylinder is injected, and a mold including a sprue serving as a passage for the injected melt and a cavity into which the melt is filled via the sprue, the injection molding method comprising: melt-kneading the injection molding resin composition according to any one of [1] to

[11] in the cylinder, injecting the obtained melt from the nozzle using the screw, and filling the cavity with the injected melt via the sprue.

[13] The injection molding method according to

[12] , wherein the temperature in the cylinder is from room temperature (25°C) to 140°C, the temperature in the nozzle is from 100°C to 140°C, and the temperature in the cavity is from 120°C to 180°C.

[0008] The resin composition for injection molding of the present invention has a well-balanced thermal stability and curability in injection molding, and is excellent in production stability during injection molding, suppressing molding defects when the resin composition is injection molded.Furthermore, an injection molding method using the composition can be provided.

[0009] 1 is a cross-sectional view showing an example of an injection molding apparatus according to an embodiment of the present invention; 2 is a cross-sectional view showing an example of an in-vehicle electronic control unit according to an embodiment of the present invention; 3 is a DSC curve obtained by DSC measurement of the sealing resin composition for injection molding obtained in Example 1;

[0010] 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. For example, "1 to 10" represents "1 or more" to "10 or less" unless otherwise specified.

[0011] The resin composition for injection molding of the present embodiment comprises (A) a thermosetting resin, (B) a curing agent, (C) an inorganic filler, and (D) a curing accelerator, and the resin composition for injection molding has a glass transition temperature of 160°C or higher and 220°C or lower, as measured by thermomechanical analysis (TMA) at a heating rate of 10°C / min, and a decrease in spiral flow of 17% or lower after storage at 30°C for 7 days.

[0012] The resin composition for injection molding of this embodiment contains components (A) to (D), and the glass transition temperature and the rate of decrease of spiral flow are within the predetermined ranges. This prevents molding defects during injection molding, and provides excellent production stability.

[0013] The present inventors focused on the glass transition temperature and spiral flow reduction rate of injection molding resin compositions and discovered that by using these as indicators, it is possible to evaluate the thermal stability and curability of a resin composition during the injection molding process, as well as the balance between these. Based on this finding, further intensive research led to the discovery that by setting these values ​​within a predetermined range, a good balance of these properties can be achieved, thereby suppressing molding defects during injection molding and achieving excellent manufacturing stability, leading to the completion of the present invention. That is, the injection molding resin composition of this embodiment contains components (A) to (D), and by having a glass transition temperature within a predetermined range and a spiral flow reduction rate within a predetermined range, the composition has a good balance of thermal stability and curability, thereby suppressing molding defects during injection molding and achieving excellent molding stability during injection molding. In other words, the glass transition temperature and the spiral flow reduction rate can be used as indicators of molding stability during injection molding.

[0014] From the viewpoint of the effects of the present invention, the glass transition temperature can be set to 160°C or higher and 220°C or lower, preferably 170°C or higher and 210°C or lower, and more preferably 175°C or higher and 200°C or lower.

[0015] From the viewpoint of the effects of the present invention, the rate of decrease in spiral flow after storage at 30° C. for 7 days can be 17% or less, preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less.

[0016] Furthermore, the resin composition for injection molding of this embodiment has a minimum torque value a of 3.3 N m or less when the torque value is measured over time using a Labo Plastomill at a rotation speed of 30 rpm and a measurement temperature of 130° C., and has a minimum torque value b of 1.2 N m or less when the torque value is measured over time at a rotation speed of 30 rpm and a measurement temperature of 150° C. When the minimum torque values ​​a and b are within the above ranges, the resin composition has excellent fluidity and moldability, which further suppresses molding defects during injection molding and provides even better molding stability during injection molding.

[0017] From the viewpoint of the above-mentioned effects, the minimum torque value a can be set to 3.3 N m or less, preferably 3.0 N m or less, more preferably 2.5 N m or less, and even more preferably 2.0 N m or less. The lower limit is not particularly limited, but can be set to 1.0 N m or more. Furthermore, from the viewpoint of the above-mentioned effects, the minimum torque value b can be set to 1.2 N m or less, preferably 1.1 N m or less, more preferably 1.0 N m or less, and even more preferably 0.8 N m or less. The lower limit is not particularly limited, but can be set to 0.3 N m or more.

[0018] Furthermore, when the torque value of the resin composition for injection molding of this embodiment is measured over time using a Labo Plastomill at a rotation speed of 30 rpm and a measurement temperature of 130°C, the time T1 during which the torque value is equal to or less than twice the minimum torque value a is 60 seconds or more and 200 seconds or less, and when the torque value is measured over time at a rotation speed of 30 rpm and a measurement temperature of 150°C, the time T1' during which the torque value is equal to or less than twice the minimum torque value b is 35 seconds or more and 100 seconds or less.

[0019] By controlling the behavior of the torque change measured under the above-mentioned specific conditions using a Labo Plastomill, the resin composition for injection molding has better flowability and filling properties during injection molding, and also has better molding stability.

[0020] From the viewpoint of the above-mentioned effects, the time T1 can be set to 60 to 200 seconds, preferably 65 to 150 seconds, more preferably 70 to 120 seconds, and even more preferably 75 to 100 seconds. Also, from the viewpoint of the above-mentioned effects, the time T1' can be set to 35 to 100 seconds, preferably 35 to 80 seconds, more preferably 35 to 70 seconds, and even more preferably 35 to 55 seconds.

[0021] Furthermore, in the resin composition for injection molding of this embodiment, in a DSC curve obtained by using a differential scanning calorimeter to raise the temperature from 30°C to 330°C at a heating rate of 10°C / min, the peak temperature of the maximum exothermic peak is 135°C or higher and lower than 175°C, and the half width of the maximum exothermic peak, determined using a straight line connecting the point at which the heat flow rate is minimum before the maximum exothermic peak and the point at which the heat flow rate is minimum after the maximum exothermic peak, as a baseline, is 32°C or lower.

[0022] In the resin composition for injection molding of this embodiment, the peak temperature of the maximum exothermic peak and the half-value width of the maximum exothermic peak are within the specified ranges, so that molding defects during injection molding are further suppressed and manufacturing stability is superior.

[0023] The peak temperature of the maximum exothermic peak can be 135°C or higher and lower than 175°C, preferably 140°C or higher and 170°C or lower, and more preferably 140°C or higher and 160°C or lower.

[0024] The half width of the maximum exothermic peak can be 32° C. or less, preferably 25° C. or less, and more preferably 20° C. or less. The lower limit is not particularly limited, but is 5° C. or more.

[0025] The glass transition temperature, the rate of decrease in spiral flow, the peak temperature and half-width of the maximum exothermic peak in a DSC curve, and the minimum torque values ​​a and b and times T1 and T1' measured with a Labo Plastomill can be controlled, for example, by appropriately adjusting the type and content of each component contained in the resin composition. In this embodiment, for example, this can be achieved by adjusting the type and content of the thermosetting resin, curing agent, inorganic filler, curing accelerator, etc.

[0026] Furthermore, the peak temperature of the maximum exothermic peak in the DSC curve can be shifted to a lower temperature by adjusting the kneading conditions (temperature and time) of the resin composition. The composition of the resin composition for injection molding of this embodiment will be described below.

[0027] [Thermosetting Resin (A)] The thermosetting resin (A) contained in the resin composition for injection molding of this embodiment includes, for example, one or more resins selected from the group consisting of epoxy resins, phenolic resins, oxetane resins, (meth)acrylate resins, unsaturated polyester resins, diallyl phthalate resins, and maleimide resins. Among these, it is particularly preferable to include an epoxy resin from the viewpoint of improving curability, storage stability, heat resistance, moisture resistance, and chemical resistance.

[0028] The epoxy resin contained in the thermosetting resin may be any monomer, oligomer, or polymer having two or more epoxy groups in one molecule, and the molecular weight or molecular structure thereof is not particularly limited. In this embodiment, the epoxy resin may be, for example, a biphenyl-type epoxy resin; a bisphenol-type epoxy resin such as a bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, or a tetramethylbisphenol F-type epoxy resin; a stilbene-type epoxy resin; a novolac-type epoxy resin such as a phenol novolac-type epoxy resin or an orthocresol novolac-type epoxy resin; a polyfunctional epoxy resin such as a trisphenol-type epoxy resin exemplified by a triphenol methane-type epoxy resin or an alkyl-modified triphenol methane-type epoxy resin; a phenol aralkyl-type epoxy resin having a phenylene skeleton, a naphthol aralkyl-type epoxy resin having a phenylene skeleton, or the like. the epoxy resins may include one or more selected from the group consisting of phenol aralkyl epoxy resins such as aralkyl epoxy resins, phenol aralkyl epoxy resins having a biphenylene skeleton, and naphthol aralkyl epoxy resins having a biphenylene skeleton; naphthol epoxy resins such as dihydroxynaphthalene epoxy resins and epoxy resins obtained by glycidyl etherifying a dihydroxynaphthalene dimer; triazine nucleus-containing epoxy resins such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; and bridged cyclic hydrocarbon compound-modified phenolic epoxy resins such as dicyclopentadiene-modified phenolic epoxy resins.

[0029] Among these, from the viewpoint of the effects of the present invention, it is preferable to contain one or more types selected from orthocresol novolac epoxy resins, phenol novolac epoxy resins, and bisphenol A epoxy resins.

[0030] The epoxy resin preferably contains a polyfunctional epoxy resin having three or more epoxy groups in the repeating structure of the epoxy resin skeleton. Use of the polyfunctional epoxy resin can improve the glass transition temperature of the cured product.

[0031] The polyfunctional epoxy resin is not particularly limited, but examples thereof include tetraphenylethane type epoxy resin, 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-(2,3-epoxypropoxy)phenyl]ethyl]phenyl]propane, tetrakis(glycidyloxyphenyl)ethane, α-2,3-epoxypropoxyphenyl-ω-hydropoly(n=1 to 7){2-(2,3-epoxypropoxy)benzylidene-2,3-epoxypropoxyphenylene}, etc. These may be used alone or in combination.

[0032] It is more preferable that the thermosetting resin (A) contains a thermosetting resin having a softening point of 110°C or less. By using a thermosetting resin having a softening point of 110°C or less, a low-viscosity injection molding resin composition can be obtained, enabling continuous injection molding, resulting in superior productivity. From the viewpoint of the above-mentioned effects, the softening point of the thermosetting resin (A) is preferably 100°C or less, more preferably 90°C or less.

[0033] The content of the thermosetting resin (A) in the injection molding resin composition is preferably 2% by mass or more, more preferably 5% by mass or more, and particularly preferably 10% by mass or more, based on the total injection molding resin composition. By setting the content of the thermosetting resin at or above the above lower limit, the fluidity during molding can be improved. Therefore, the resin composition has better room temperature storage stability, and can also improve filling properties and molding stability. On the other hand, the content of the thermosetting resin in the injection molding resin composition is preferably 50% by mass or less, more preferably 40% by mass or less, and particularly preferably 25% by mass or less, based on the total injection molding resin composition. Setting the content of the thermosetting resin at or below the above upper limit makes the resin composition stable against heat treatment in an injection molding extruder and shortens the molding cycle.

[0034] [Curing Agent (B)] The curing agent (B) contained in the resin composition for injection molding of this embodiment can be roughly divided into three types: polyaddition type curing agents, catalyst type curing agents, and condensation type curing agents.

[0035] Examples of polyaddition type curing agents used as the curing agent (B) include aliphatic polyamines such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylylenediamine (MXDA), aromatic polyamines such as diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), and diaminodiphenylsulfone (DDS), as well as polyamine compounds including dicyandiamide (DICY) and organic acid dihydralazides; and alicyclic acid anhydrides such as hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA), etc. the curing agent may comprise one or more selected from the group consisting of: acid anhydrides including aromatic acid anhydrides such as trimellitic anhydride (TMA), pyromellitic anhydride (PMDA), benzophenonetetracarboxylic acid (BTDA), and the like; phenolic resin-based curing agents such as novolac-type phenolic resins, polyvinylphenols, and aralkyl-type phenolic resins; polymercaptan compounds such as polysulfides, thioesters, and thioethers; isocyanate compounds such as isocyanate prepolymers and blocked isocyanates; and organic acids such as carboxylic acid-containing polyester resins.

[0036] The catalyst type curing agent used as the curing agent (B) includes one or more selected from the group consisting of tertiary amine compounds such as benzyldimethylamine (BDMA) and 2,4,6-trisdimethylaminomethylphenol (DMP-30); and Lewis acids such as BF complexes.

[0037] The condensation type curing agent used as the curing agent (B) includes, for example, one or more selected from the group consisting of resol type phenolic resins; urea resins such as methylol group-containing urea resins; and melamine resins such as methylol group-containing melamine resins.

[0038] Among these, it is more preferable to include a phenolic resin-based curing agent from the viewpoint of improving the balance of flame resistance, moisture resistance, electrical properties, curability, storage stability, etc. As the phenolic resin-based curing agent, any monomer, oligomer, or polymer having two or more phenolic hydroxyl groups in one molecule can be used, and the molecular weight and molecular structure thereof are not particularly limited. The phenolic resin-based curing agent used as a curing agent includes one or more selected from the group consisting of novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol novolac; polyvinylphenol; multifunctional phenolic resins such as triphenolmethane-type phenolic resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; phenol aralkyl-type phenolic resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton and naphthol aralkyl resins having a phenylene and / or biphenylene skeleton; and bisphenol compounds such as bisphenol A and bisphenol F. Among these, from the viewpoint of improving the curability of the resin composition for injection molding, it is more preferable to include at least one of a novolac type phenolic resin and a phenol aralkyl type phenolic resin.

[0039] The content of the curing agent (B) in the injection molding resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, and particularly preferably 3% by mass or more, based on the total injection molding resin composition. By setting the curing agent content at or above the above lower limit, the resin composition can be more excellent in room temperature storage stability, and can achieve excellent fluidity during molding, thereby improving filling and moldability. On the other hand, the content of the curing agent in the injection molding resin composition is preferably 40% by mass or less, more preferably 25% by mass or less, and particularly preferably 10% by mass or less, based on the total injection molding resin composition. By setting the curing agent content at or below the above upper limit, the resin composition is stable against heat treatment in an injection molding extruder and can shorten the molding cycle.

[0040] [Inorganic Filler (C)] The inorganic filler (C) contained in the resin composition for injection molding of this embodiment may include, for example, one or more selected from the group consisting of glass fiber, silica such as fused crushed silica, spherical silica, and crystalline silica, alumina, aluminum hydroxide, magnesium hydroxide, calcium carbonate, silicon nitride, and aluminum nitride. Among these, from the viewpoint of excellent versatility, glass fiber, spherical silica, fused crushed silica, and calcium carbonate are preferred, and spherical silica and fused crushed silica are more preferred.

[0041] When the inorganic filler (C) contains silica, for example, the average particle size D ５０ It is preferable that the silica has an average particle diameter D of 1 μm or more and 50 μm or less. This makes it possible to more effectively improve the balance of filling properties, adhesion, moisture resistance, heat resistance, etc. ５０ can be measured using, for example, a commercially available laser particle size distribution analyzer (for example, SALD-7000 manufactured by Shimadzu Corporation).

[0042] The content of the inorganic filler (C) in the injection molding resin composition is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total resin composition. By setting the content of the inorganic filler at or above the above lower limit, low moisture absorption and low thermal expansion can be improved, and the moisture resistance reliability of the encapsulant can be more effectively improved. On the other hand, the upper limit of the content of the inorganic filler (C) in the injection molding resin composition is not particularly limited, but can be set to about 98% by mass or less based on the total injection molding resin composition. By setting the content of the inorganic filler (C) at or below the above upper limit, it is possible to more effectively improve the fluidity and filling property of the injection molding resin composition during molding.

[0043] [Curing Accelerator (D)] The curing accelerator (curing catalyst) (D) contained in the resin composition for injection molding of this embodiment may be any known curing accelerator that accelerates the reaction between the thermosetting resin and the curing agent. Examples of the curing accelerator (D) include phosphorus-based curing accelerators, imidazole-based curing accelerators, and nitrogen-based curing accelerators.

[0044] Examples of the phosphorus-based curing accelerator include organic phosphines, tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, and adducts of phosphonium compounds and silane compounds, and at least one selected from these can be used.

[0045] Examples of organic phosphines include primary phosphines such as ethylphosphine and phenylphosphine; secondary phosphines such as dimethylphosphine and diphenylphosphine; and tertiary phosphines such as trimethylphosphine, triethylphosphine, tributylphosphine, tris(4-methylphenyl)phosphine and tris(4-methoxyphenyl)phosphine, and one or more selected from these can be used in combination. As the organic phosphine, tris(4-methylphenyl)phosphine or tris(4-methoxyphenyl)phosphine is preferred.

[0046] Examples of the tetra-substituted phosphonium compound include compounds represented by the following general formula (6).

[0047]

[0048] In the general formula (6), P represents a phosphorus atom. ４ , R ５ , R ６ and R ７each independently represents an aromatic group or an alkyl group. A represents the anion of an aromatic organic acid having at least one functional group selected from a hydroxyl group, a carboxyl group, and a thiol group on the aromatic ring. AH represents an aromatic organic acid having at least one functional group selected from a hydroxyl group, a carboxyl group, and a thiol group on the aromatic ring. x and y are 1 to 3, z is 0 to 3, and x=y.

[0049] The compound represented by general formula (6) can be obtained, for example, as follows. First, a tetra-substituted phosphonium halide, an aromatic organic acid, and a base are mixed uniformly in an organic solvent, and an aromatic organic acid anion is generated in the solution system. Then, water is added to precipitate the compound represented by general formula (6). In the compound represented by general formula (6), R bonded to the phosphorus atom ４ , R ５ , R ６ and R ７ is preferably a phenyl group, AH is a compound having a hydroxyl group on an aromatic ring, i.e., a phenol, and A is an anion of the phenol. Examples of the phenol include monocyclic phenols such as phenol, cresol, resorcinol, and catechol, condensed polycyclic phenols such as naphthol, dihydroxynaphthalene, and anthraquinol, bisphenols such as bisphenol A, bisphenol F, and bisphenol S, and polycyclic phenols such as phenylphenol and biphenol.

[0050] Specific examples of the tetra-substituted phosphonium compound include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrakis(4-methylphenyl)borate, tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate, molecular compounds of tetraphenylphosphonium and bisphenols, and complex salts of tetraphenylphosphonium and dihydroxynaphthalenes.

[0051] Examples of the phosphobetaine compound include compounds represented by the following general formula (7).

[0052]

[0053] In the general formula (7), P represents a phosphorus atom. ８ is an alkyl group having 1 to 3 carbon atoms, R ９ represents a hydroxyl group, f is 0 to 5, and g is 0 to 3.

[0054] The compound represented by general formula (7) can be obtained, for example, as follows: First, a triaromatic-substituted phosphine, which is a tertiary phosphine, is brought into contact with a diazonium salt to substitute the diazonium group of the diazonium salt with the triaromatic-substituted phosphine.

[0055] Specific examples of the phosphobetaine compound include 2-(triphenylphosphonium)phenolate, 4-hydroxy-2-(triphenylphosphonium)phenolate, 3-(triphenylphosphonium)phenolate, an adduct of triphenylphosphine and 1,4-benzoquinone, etc. Examples of the adduct of a phosphine compound and a quinone compound include a compound represented by the following general formula (8):

[0056]

[0057] In the general formula (8), P represents a phosphorus atom. １０ , R １１ and R １２ represents an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms, and may be the same or different. １３ , R １４ and R １５ represent a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, and may be the same or different from each other; R １４ and R １５ may be bonded to form a cyclic structure.

[0058] The phosphine compound used in the adduct of a phosphine compound and a quinone compound is preferably, for example, triphenylphosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, trinaphthylphosphine, tris(benzyl)phosphine, etc., which is unsubstituted or has a substituent such as an alkyl group or alkoxy group on the aromatic ring, and the substituent such as the alkyl group or alkoxy group has a carbon number of 1 to 6. From the viewpoint of availability, triphenylphosphine is preferred.

[0059] The quinone compound used in the adduct of a phosphine compound and a quinone compound includes benzoquinone and anthraquinones, and among these, p-benzoquinone is preferred from the viewpoint of storage stability.

[0060] The adduct of a phosphine compound and a quinone compound can be produced by contacting and mixing the organic tertiary phosphine and the benzoquinone in a solvent that can dissolve both of them. The solvent is preferably a ketone such as acetone or methyl ethyl ketone, which has low solubility in the adduct, but is not limited thereto.

[0061] In the compound represented by the general formula (8), R bonded to the phosphorus atom １０ , R １１ and R １２ is a phenyl group, and R １３ , R １４ and R １５ is a hydrogen atom, that is, a compound obtained by adding 1,4-benzoquinone and triphenylphosphine, is preferred in that it reduces the modulus of elasticity of the cured product of the encapsulating resin composition when heated.

[0062] Examples of the adduct of a phosphonium compound and a silane compound include compounds represented by the following general formula (9).

[0063]

[0064] In the general formula (9), P represents a phosphorus atom, and Si represents a silicon atom. １６ , R １７ , R １８ and R１９ R each represents an organic group having an aromatic ring or a heterocyclic ring, or an aliphatic group, and may be the same or different from each other. ２０ is the group Y ２ and Y ３ R is an organic group that bonds to ２１ is the group Y ４ and Y ５ It is an organic group that bonds to

[0065] Y ２ and Y ３ represents a group formed by releasing a proton from a proton-donating group, and a group Y ２ and Y ３ is bonded to a silicon atom to form a chelate structure. ４ and Y ５ represents a group formed by releasing a proton from a proton-donating group, and a group Y ４ and Y ５ is bonded to a silicon atom to form a chelate structure. ２０ , and R ２１ may be the same or different, and Y ２ , Y ３ , Y ４ and Y ５ may be the same or different. Z1 is an organic group having an aromatic ring or a heterocyclic ring, or an aliphatic group.

[0066] In general formula (9), R １６ , R １７ , R １８ and R １９ Examples of the alkyl group include a phenyl group, a methylphenyl group, a methoxyphenyl group, a hydroxyphenyl group, a naphthyl group, a hydroxynaphthyl group, a benzyl group, a methyl group, an ethyl group, an n-butyl group, an n-octyl group, and a cyclohexyl group. Among these, an aromatic group having a substituent such as an alkyl group, an alkoxy group, or a hydroxyl group, such as a phenyl group, a methylphenyl group, a methoxyphenyl group, a hydroxyphenyl group, or a hydroxynaphthyl group, or an unsubstituted aromatic group is more preferred.

[0067] In general formula (9), R２０ Is Y ２ and Y ３ Similarly, R ２１ is the group Y ４ and Y ５ is an organic group that bonds to ２ and Y ３ is a group formed by releasing a proton from a proton-donating group, and the group Y ２ and Y ３ is bonded to a silicon atom to form a chelate structure. ４ and Y ５ is a group formed by releasing a proton from a proton-donating group, and the group Y ４ and Y ５ is bonded to a silicon atom to form a chelate structure. ２０ and R ２１ may be the same or different, and the group Y ２ , Y ３ , Y ４ and Y5 may be the same or different from each other. ２ -R ２０ -Y ３ -, and Y ４ -R ２１ -Y ５The group represented by - is constituted by a group formed by a proton donor releasing two protons, and as the proton donor, an organic acid having at least two carboxyl groups or hydroxyl groups in the molecule is preferred, and an aromatic compound having at least two carboxyl groups or hydroxyl groups on adjacent carbons constituting an aromatic ring is more preferred, and an aromatic compound having at least two hydroxyl groups on adjacent carbons constituting an aromatic ring is more preferred, and examples thereof include catechol, pyrogallol, 1,2-dihydro- Examples of the dihydroxynaphthalene include xynaphthalene, 2,3-dihydroxynaphthalene, 2,2'-biphenol, 1,1'-bi-2-naphthol, salicylic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, chloranilic acid, tannic acid, 2-hydroxybenzyl alcohol, 1,2-cyclohexanediol, 1,2-propanediol, and glycerin. Of these, catechol, 1,2-dihydroxynaphthalene, and 2,3-dihydroxynaphthalene are more preferred.

[0068] Z in general formula (9) １ represents an organic group or an aliphatic group having an aromatic ring or a heterocyclic ring, and specific examples thereof include aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl groups; aromatic hydrocarbon groups such as phenyl, benzyl, naphthyl, and biphenyl groups; glycidyloxy groups such as glycidyloxypropyl, mercaptopropyl, and aminopropyl groups; mercapto groups; alkyl groups having amino groups; and reactive substituents such as vinyl groups. Among these, methyl, ethyl, phenyl, naphthyl, and biphenyl groups are more preferred in terms of thermal stability.

[0069] An example of a method for producing an adduct of a phosphonium compound and a silane compound is as follows. A silane compound such as phenyltrimethoxysilane and a proton donor such as 2,3-dihydroxynaphthalene are dissolved in a flask containing methanol, and then a sodium methoxide-methanol solution is added dropwise to the solution with stirring at room temperature. A previously prepared solution of a tetra-substituted phosphonium halide such as tetraphenylphosphonium bromide dissolved in methanol is then added dropwise to the solution with stirring at room temperature, resulting in the precipitation of crystals. The precipitated crystals are filtered, washed with water, and vacuum dried to obtain an adduct of a phosphonium compound and a silane compound.

[0070] From the viewpoint of the effects of the present invention, the phosphorus-based curing accelerator is preferably at least one selected from organic phosphines, tetra-substituted phosphonium compounds, and phosphobetaine compounds.

[0071] Examples of imidazole curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole (EMI24), 2-phenyl-4-methylimidazole (2P4MZ), 2-phenyl-1H-imidazole 4,5-dimethanol, 2-phenyl-4,5-dihydroxymethylimidazole, 1-benzyl-2-phenylimidazole, and 1-benzyl-2-phenylimidazole. benzyl-2-methylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4-methylimidazolyl(1')]-ethyl-s-triazine, isocyanuric acid adduct of 2,4-diamino-6-[2'-methylimidazolyl(1')]-ethyl-s-triazine, isocyanuric acid adduct of 2-phenylimidazole Examples of the alkylating agent include a socyanuric acid adduct, an isocyanuric acid adduct of 2-methylimidazole, 2-phenyl-4,5-dihydroxydimethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine, and at least one selected from these can be used.

[0072] As the imidazole curing accelerator, from the viewpoint of the effects of the present invention, it is preferable to use at least one selected from 2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-benzyl-2-phenylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 2-phenyl-1H-imidazole-4,5-dimethanol, and 2-phenyl-4,5-dihydroxymethylimidazole.

[0073] Examples of the nitrogen-based curing accelerator include amidines and tertiary amines, such as 1,8-diazabicyclo[5.4.0]undecene-7 and benzyldimethylamine, and quaternary salts of amidines and amines.

[0074] In this embodiment, the curing accelerator (D) preferably contains a phosphorus-based curing accelerator and an imidazole-based curing accelerator, which provides an even better balance between rapid curing and room temperature storage stability in injection molding, resulting in excellent moldability and manufacturing stability.

[0075] In this embodiment, the lower limit of the content of the curing accelerator (D) is, for example, preferably 0.01% by mass or more, and more preferably 0.15% by mass or more, based on the total solid content of the injection molding resin composition. By setting the content of the curing accelerator to the above-mentioned lower limit or more, it is possible to effectively improve the curability during molding. On the other hand, the upper limit of the content of the curing accelerator is, for example, preferably 5.0% by mass or less, and more preferably 3.0% by mass or less, based on the total solid content of the injection molding resin composition. By setting the content of the curing accelerator to the above-mentioned upper limit or less, it is possible to improve the flowability during molding.

[0076] [Mold Release Agent (E)] The resin composition for injection molding of this embodiment may further contain a mold release agent (E).

[0077] Examples of the release agent (E) include carnauba wax, stearic acid, montanic acid, metal stearates, polyethylene oxide, and a reaction product of a condensate of an alkene and maleic anhydride with stearyl alcohol, and the like, and one or more selected from these may be used in combination. In this embodiment, the release agent (E) preferably contains stearic acid.

[0078] The content of the release agent (E) in the resin composition for injection molding is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, based on the total resin composition. By setting the content of the release agent (E) to be equal to or greater than the above-mentioned lower limit, the resin composition has excellent mold releasability and therefore excellent moldability. On the other hand, the content of the release agent (E) in the resin composition for injection molding is preferably 2% by mass or less, more preferably 1% by mass or less, based on the total resin composition for injection molding. By setting the content of the release agent (E) to be equal to or less than the above-mentioned upper limit, the resin composition for injection molding has an excellent balance of mold releasability, fluidity, and filling properties during molding.

[0079] (Other Components) The resin composition for injection molding of this embodiment may contain, as needed, one or more of various additives such as a silane coupling agent, a colorant, an ion scavenger, an oil, a stress reducing agent, a flame retardant, etc. The resin composition for injection molding of this embodiment can be obtained by mixing the above components by a conventionally known method.

[0080] <Injection Molding Method> The injection molding method of this embodiment can be performed using an injection molding apparatus 1 shown in FIG.

[0081] The injection molding apparatus 1 is composed of an injection unit 20 having a cylinder 21, a screw 22 inserted into the cylinder 21, and a nozzle 25 through which a molten resin composition for injection molding that has been melt-kneaded by the screw 22 within the cylinder 21 is injected, and a mold 10 having a sprue 11 that serves as a passage for the injected molten material, and a cavity 12 into which the molten material is filled via the sprue 11.

[0082] The injection molding method of this embodiment includes the steps of melt-kneading the injection molding resin composition of this embodiment in a cylinder 21, injecting the resulting melt from a nozzle 25 using a screw 22, and filling the injected melt into a cavity 12 via a sprue 11.

[0083] The injection molding apparatus 1 includes a mold 10 having a molding space (cavity 12) including a gate, a runner, and a gate, and an injection molding machine 20 for performing injection molding. The injection molding machine 20 includes, for example, a cylinder 21, a screw 22 rotatable within the cylinder 21, a hopper 23 into which a resin composition for injection molding can be introduced into the cylinder 21, a heater 24 that heats the phenolic resin composition via the cylinder 21, and a nozzle 25 that delivers the molding material kneaded within the cylinder 21 to the mold 10. The screw 22 has a check valve 26 at its tip.

[0084] In the injection molding method of this embodiment, first, a resin composition for injection molding is charged into a heated injection molding machine 20. The resin composition for injection molding is then heated and melted by a heater 24 in a cylinder 21, while being kneaded by a screw 22. The temperature inside the cylinder 21 varies depending on the position in the longitudinal direction of the cylinder 21, but is adjusted within a range of room temperature (25°C) or higher and 140°C or lower. The temperature T at the tip of the screw 22 inside the cylinder 21 is 50°C or higher and 140°C or lower.

[0085] The injection molding resin composition (melt) melted by the screw 22 is sent toward the nozzle 25 while being compressed and kneaded, while the screw 22 moves backward (in the opposite direction from the nozzle 25). At this time, back pressure is applied to the screw 22 from the rear, so that pressure can be applied to the injection molding resin composition that has gathered at the nozzle 25. Then, the injection molding resin composition that has gathered at the nozzle 25 at the tip of the screw 21 is metered to a set position. The injection molding resin composition of this embodiment is prevented from sticking to the screw, etc., and can be metered accurately.

[0086] The measured injection molding resin composition (melt) is then injected from the nozzle 25 by the pressure of the screw 22 as the screw 21, which has been lowered backward, advances. The injected melt fills the cavity 12 of the mold 10 via the sprue 11, sealing the target object. The injection molding resin composition of this embodiment has excellent moldability, and backflow of the injection molding resin composition in the cylinder into the hopper during injection is suppressed. The temperature inside the nozzle 25 is 100°C or higher and 140°C or lower. The temperature inside the cavity 12 is 120°C or higher and 180°C or lower.

[0087] The injection molding resin composition is cured in the cavity 12, and then the mold 10 is opened and the molded article is removed from the cavity 12. The injection molding resin composition of this embodiment has excellent mold releasability. In this embodiment, an in-vehicle electronic control unit or the like sealed with the injection molding resin composition can be provided. In this embodiment, the injection molding resin composition can be used as an injection molding sealing resin composition. The following description will be given taking an in-vehicle electronic control unit as an example.

[0088] [On-Vehicle Electronic Control Unit] An on-vehicle electronic control unit 30 is used to control an engine, various on-vehicle devices, etc. As shown in FIG. 1 , the on-vehicle electronic control unit 30 includes, for example, a wiring board 32, a plurality of electronic components 36 mounted on at least one surface of the wiring board 32, and a sealing resin 34 made of the injection molding resin composition of the present embodiment that seals the electronic components 36. The wiring board 32 has connection terminals 38 on at least one side for connecting to an external device. The on-vehicle electronic control unit 30 according to this example embodiment is electrically connected to a mating connector via the connection terminals 38 by mating the connection terminals 38 with the mating connector.

[0089] The wiring board 32 is a wiring board having circuit wiring provided on one or both of one surface and the other surface opposite the one surface. As shown in FIG. 1 , the wiring board 32 has, for example, a flat plate shape. In this embodiment, an organic substrate formed of an organic material such as polyimide can be used as the wiring board 32. The wiring board 32 may have, for example, through holes 40 that penetrate the wiring board 32 and connect one surface to the other surface. In this case, the wiring provided on one surface of the wiring board 32 and the wiring provided on the other surface are electrically connected via a conductor pattern provided in the through holes 40.

[0090] The wiring board 32 has a solder resist layer on one side on which the electronic components 36 are mounted, for example. The solder resist layer can be formed using a resin composition for forming a solder resist that is commonly used in the field of semiconductor devices. In this embodiment, the solder resist layer can be provided on both one side and the other side of the wiring board 32, for example.

[0091] The solder resist layer provided on one surface or on both surfaces of the wiring board 32 is formed from a resin composition containing, for example, a silicone compound, thereby realizing a solder resist layer with excellent surface smoothness.

[0092] 2, the plurality of electronic components 36 are mounted, for example, on one surface and the other surface of the wiring board 32. On the other hand, the electronic components 36 may be provided only on one surface of the wiring board 32, and may not be provided on the other surface of the wiring board 32. The electronic components 36 are not particularly limited as long as they can be mounted in an in-vehicle electronic control unit, and may be, for example, a microcomputer.

[0093] The sealing resin 34 is formed by molding and curing the injection molding resin composition of this embodiment so as to seal the electronic components 36. In this embodiment, the sealing resin 34 is formed, for example, to seal the wiring board 32 together with the electronic components 36. In the example shown in FIG. 2 , the sealing resin 34 is provided so as to seal one and the other sides of the wiring board 32 and the electronic components 36 mounted on the wiring board 32. The sealing resin 34 is also formed, for example, to seal a part or all of the wiring board 32. FIG. 2 illustrates an example in which the sealing resin 34 is provided so as to seal the entire wiring board 32 without sealing the connection terminals 38, so that the connection terminals 38 are exposed.

[0094] In the in-vehicle electronic control unit 30 of this embodiment, the wiring board 32 may be mounted on, for example, a metal base. The metal base can function as a heat sink for dissipating heat generated by, for example, the electronic components 36. In this embodiment, the in-vehicle electronic control unit 30 can be formed, for example, by integrally encapsulating the metal base and the wiring board 32 mounted on the metal base with an injection molding resin composition. The metal material constituting the metal base is not particularly limited, but may include, for example, iron, copper, aluminum, and alloys containing one or more of these metals. Note that the in-vehicle electronic control unit 30 does not necessarily have a metal base. The in-vehicle electronic control unit 30 illustrated in FIG. 2 is formed by encapsulating multiple electronic components 36 with the injection molding resin composition of this embodiment by injection molding.

[0095] Specifically, first, a wiring board 32 on which a plurality of electronic components 36 are mounted is placed in a cavity 12 of a mold 10. The shape of the cavity 12 is appropriately modified to match the shape of the in-vehicle electronic control unit 30. Then, the injection molding resin composition of this embodiment is poured into a cylinder 21 having a screw 22 therein via a hopper 23, and the injection molding resin composition is melted. The molten material is moved through the cylinder 21 by the screw 22, injected through a nozzle 25, and filled into the mold cavity 12 via a sprue 11, sealing in the plurality of electronic components 36.

[0096] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted as long as they do not impair the effects of the present invention.

[0097] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0098] [Examples 1-2 and Comparative Examples 1-2] For each of Examples 1-2 and Comparative Examples 1-2, an encapsulating resin composition was prepared as follows. First, the components were premixed for 20 minutes in a Henschel mixer (200 liter capacity, 900 rpm) set at room temperature according to the formulation shown in Table 1. The resulting mixture was then finely pulverized using a continuous rotary ball mill (Dynamic Mill MYD25, manufactured by Nippon Coke Engineering Co., Ltd., 500 rpm screw rotation speed, 10 mm alumina ball diameter, 50% ball volume filling rate relative to the device capacity) at a material supply rate of 200 kg / hr while maintaining the material temperature at 30°C or below. The finely pulverized mixture was then kneaded using two 10-inch roll mills. The roll temperatures were set to 105°C and 15°C, respectively. The kneading time was 5 minutes. The kneading time for Example 4 was 20 minutes, and that for Example 5 was 40 minutes. The kneaded mixture was then cooled and pulverized to obtain an encapsulating resin composition. The steps from pre-mixing using a Henschel mixer to obtaining the encapsulating resin composition were carried out continuously. The details of each component in Table 1 are as follows. The units in Table 1 are mass %.

[0099] (A) Thermosetting Resin Epoxy resin: orthocresol novolac epoxy resin (EPICLON N-670, manufactured by DIC Corporation), epoxy equivalent: 210 g / Eq, softening point: 72°C

[0100] (B) Curing agent Phenolic resin: Novolac type phenolic resin (PR-51470, manufactured by Sumitomo Bakelite Co., Ltd.)

[0101] (C) Inorganic filler: Glass fiber: Cut length 3 mm, filament diameter 10 μm; Silica: Crushed silica (average particle size D ５０ = 15 μm)

[0102] (D) Curing accelerator Curing catalyst 1: 2-phenyl-4,5-dihydroxymethylimidazole (melting point 225-235°C, molecular weight 204) represented by the following chemical formula

[0103] Curing catalyst 2: 4-hydroxy-2-(triphenylphosphonium)phenolate Curing catalyst 3: 2-phenylimidazole (melting point 137-147°C, molecular weight 144, active temperature range 105-125°C) Curing catalyst 4: triphenylphosphine

[0104] Other ingredients: Low stress agent: Silicone rubber (Kane Ace M711, manufactured by Kaneka Corporation), release agent: Carnauba wax, colorant: Carbon black

[0105] (Glass transition temperature (Tg)) A JIS 6911 bending test piece was molded at 175°C for 3 minutes, and TMA measurement was carried out in the flow direction, and the bending point was taken as Tg. The measurement was carried out at a temperature increase rate of 10°C / min.

[0106] (Reduction in Spiral Flow After Storage at 30°C for 7 Days) The encapsulating resin compositions obtained in each Example and Comparative Example were placed in a sealed container in a thermostatic chamber at 30°C and stored for 7 days, and the reduction in spiral flow was measured under the following conditions. Using a low-pressure transfer molding machine ("KTS-15" manufactured by Kotaki Seiki Co., Ltd.), the resin composition before storage was injected into a mold for spiral flow measurement in accordance with EMMI-1-66 under conditions of a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a curing time of 180 seconds, and the flow length a was measured. Furthermore, the flow length b of the resin composition after storage at 30°C for 7 days was measured in the same manner. The reduction in spiral flow (%) after storage at 30°C for 7 days was calculated using the following formula: [(Flow length a - Flow length b) / Flow length a] x 100

[0107] (Thermal Stability Test) ISO178 dumbbell test pieces (test pieces) were molded using a 100-ton electric injection molding machine (product number: EC-100SXR, manufactured by Shibaura Machine Co., Ltd.). The mold temperature of the 100-ton electric injection molding machine was set to 165°C, and the nozzle temperatures were set to 85°C / 65°C / 45°C. The injection time was set to 15 seconds, and the curing time was set to 100 seconds. The injection speed was 5 mm / s, and the dwell pressure was set to 30 MPa for 5 seconds. Injection molding was performed with an injection waiting time of 0 or 5 minutes after weighing, and the total weight of the resulting test pieces (2 ISO test pieces + sprue + runner) was measured. The weight when injection molded with a waiting time of 0 minutes was defined as W0, and the weight when injection molded with a waiting time of 5 minutes was defined as W5. Test pieces with (W5 / W0) x 100 of 98% or more were rated A, and those with a value of less than 98% were rated C.

[0108] [Gel Time (GT)] After each of the encapsulating resin compositions of Examples and Comparative Examples was melted on a hot plate heated to 175°C, the time (unit: seconds) until the composition hardened was measured while kneading with a spatula.

[0109] (DSC Measurement) The encapsulating resin composition obtained in each Example and Comparative Example was finely pulverized in a mortar and pestle, and 3 to 5 mg was weighed into an aluminum pan to prepare a sample. Next, differential scanning calorimetry was performed on the sample using a differential scanning calorimeter (DSC7020, Hitachi High-Tech Science Corporation) under the following conditions: starting temperature 30°C, measurement temperature range 30 to 330°C, and temperature rise rate 10°C / min. From the obtained DSC curve, the peak temperature (°C) of the maximum exothermic peak and the half-width (°C) of the maximum exothermic peak were calculated.

[0110] FIG. 3 shows a DSC curve obtained by DSC measurement of the encapsulating resin composition obtained in Example 1. Below, using Example 1 as an example, the method for calculating the half-width (°C) of the maximum exothermic peak in each Example and Comparative Example will be described. The half-width (°C) of the maximum exothermic peak was calculated as follows. First, a straight line connecting point A (the minimum temperature before the maximum exothermic peak) where the heat flow is minimum before the maximum exothermic peak and point B (the minimum temperature after the maximum exothermic peak) where the heat flow is minimum after the maximum exothermic peak was determined as a baseline. Next, point D was determined as the intersection point between a perpendicular line to the X-axis passing through point C (where the heat flow of the exothermic peak is maximum) and the baseline. Next, a straight line passing through point E, the midpoint of line CD, and parallel to the X-axis was drawn. The points at which the line intersects with the DSC curve were determined as points F and F', respectively. The length of line FF' was determined as the half-width.

[0111] (Measurement of Times T1, T1', and Minimum Torque Values ​​a, b in a Labo Plastomill Tester) The times T1, T1', and minimum torque values ​​for the encapsulating resin compositions obtained in each Example and Comparative Example were measured as follows. First, the melt torque of the encapsulating resin composition was measured over time using a Labo Plastomill tester (4C150, manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a rotation speed of 30 rpm and a measurement temperature of 130°C. Next, the time T1 at which the torque value was equal to or less than twice the minimum torque value was calculated based on the measurement results. The measurement start point was the point at which the torque started to decrease after the material was loaded into the Labo Plastomill tester. The minimum torque value a was also calculated from the measurement results. Similarly, the melt torque of the encapsulating resin composition was measured over time at a rotation speed of 30 rpm and a measurement temperature of 150°C, and the time T1' at which the torque value was equal to or less than twice the minimum torque value and the minimum torque value b were calculated based on the measurement results. The results are shown in Table 1. In Table 1, the times T1 and T1' are in seconds, and the minimum torque values ​​a and b are in N·m.

[0112] (Coefficient of linear expansion CTE1) The resin composition obtained in each example was injection molded using a transfer molding machine at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 180 seconds to obtain a test piece with a long side of 15 mm, a short side of 4.5 mm, and a thickness of 3 mm. The obtained test piece was post-cured at 175 ° C for 4 hours, and then measured using a thermomechanical analyzer (Hitachi High-Tech Science, TMA7100) in compression mode under the conditions of a measurement temperature range of -60 ° C to 400 ° C and a heating rate of 5 ° C / min. From the measurement results, the average coefficient of linear expansion from 50 ° C to 70 ° C was calculated and designated as CTE1.

[0113]

[0114] As shown in Table 1, the resin compositions for injection molding of the examples have excellent thermal stability, high Tg and excellent curing properties, and have a good balance of these properties. Therefore, it has become clear that the compositions are stable against heat treatment in injection molding and are suitable for use in injection molding, which has a short molding cycle.

[0115] This application claims priority based on Japanese Patent Application No. 2024-048373, filed March 25, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0116] REFERENCE SIGNS LIST 1 injection molding device 10 mold 11 sprue 12 cavity 20 injection molding machine 21 cylinder 22 screw 23 hopper 24 heater 25 nozzle 26 backflow valve 30 on-vehicle electronic control unit 32 wiring board 34 sealing resin 36 electronic component 38 connection terminal 40 through hole

Claims

1. (A) a thermosetting resin; (B) a curing agent; (C) an inorganic filler; (D) a curing accelerator; The curing accelerator (D) is an injection-molding resin composition containing a phosphorus-based curing accelerator and an imidazole-based curing accelerator, the glass transition temperature of the resin composition for use in injection molding is 160°C or higher and 220°C or lower, as measured by thermomechanical analysis (TMA) at a heating rate of 10°C / min; A resin composition for injection molding, which has a spiral flow reduction rate of 17% or less after storage at 30°C for 7 days.

2. When the torque value is measured over time using a Labo Plastomill at a rotation speed of 30 rpm and a measurement temperature of 130°C, the minimum torque value a is 3.3 N m or less, 2. The resin composition for injection molding according to claim 1, wherein the minimum torque value b is 1.2 N·m or less when the torque value is measured over time at a rotation speed of 30 rpm and a measurement temperature of 150°C.

3. When the torque value is measured over time using a Laboplastomill at a rotation speed of 30 rpm and a measurement temperature of 130°C, the time T1 during which the torque value is equal to or less than twice the minimum torque value a is 60 seconds or more and 200 seconds or less, 3. The resin composition for injection molding according to claim 1, wherein, when the torque value is measured over time at a rotation speed of 30 rpm and a measurement temperature of 150°C, the time T1' during which the torque value is equal to or less than twice the minimum torque value b is 35 seconds or more and 100 seconds or less.

4. 3. The resin composition for injection molding according to claim 1, wherein the phosphorus-based curing accelerator is at least one selected from the group consisting of organic phosphines, tetra-substituted phosphonium compounds, and phosphobetaine compounds.

5. the organic phosphine is tris(4-methylphenyl)phosphine or tris(4-methoxyphenyl)phosphine; The tetra-substituted phosphonium compound is tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrakis(4-methylphenyl)borate, tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate, a molecular compound of tetraphenylphosphonium and a bisphenol, or a complex salt of tetraphenylphosphonium and a dihydroxynaphthalene, 5. The resin composition for injection molding according to claim 4, wherein the phosphobetaine compound is 2-(triphenylphosphonium)phenolate, 4-hydroxy-2-(triphenylphosphonium)phenolate, 3-(triphenylphosphonium)phenolate, or an adduct of triphenylphosphine and 1,4-benzoquinone.

6. 3. The resin composition for injection molding according to claim 1, wherein the imidazole curing accelerator is at least one selected from the group consisting of 2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-benzyl-2-phenylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 2-phenyl-1H-imidazole-4,5-dimethanol, and 2-phenyl-4,5-dihydroxymethylimidazole.

7. 3. The resin composition for injection molding according to claim 1, wherein the thermosetting resin (A) has a softening point of 110°C or lower.

8. The resin composition for injection molding according to claim 1 or 2, further comprising a mold release agent (E).

9. In the DSC curve obtained by using a differential scanning calorimeter and heating from 30°C to 330°C at a heating rate of 10°C / min, The peak temperature of the maximum exothermic peak is 135°C or higher and lower than 175°C, 3. The resin composition for injection molding according to claim 1, wherein the full width at half maximum of the maximum exothermic peak is 32°C or less, as determined using a straight line connecting the point at which the heat flow rate is smallest before the maximum exothermic peak and the point at which the heat flow rate is smallest after the maximum exothermic peak as a baseline.

10. an injection unit including a cylinder, a screw inserted into the cylinder, and a nozzle through which a molten resin composition for injection molding melt-kneaded by the screw in the cylinder is injected; a mold including a sprue serving as a passage for the injected molten material and a cavity into which the molten material is filled via the sprue; A resin composition for injection molding used in an injection molding apparatus comprising: The temperature inside the cylinder is between room temperature (25°C) and 140°C, The temperature inside the nozzle is 100°C or higher and 140°C or lower, 3. The resin composition for injection molding according to claim 1, wherein the temperature inside the cavity is 120°C or higher and 180°C or lower.

11. an injection unit including a cylinder, a screw inserted into the cylinder, and a nozzle through which a molten material melted and kneaded by the screw in the cylinder is injected; a mold including a sprue serving as a passage for the injected molten material and a cavity into which the molten material is filled via the sprue; An injection molding method using an injection molding apparatus comprising: a step of melt-kneading the resin composition for injection molding according to claim 1 or 2 in the cylinder; Injecting the resulting melt from the nozzle using the screw; a step of filling the injected molten material into the cavity through the sprue; An injection molding method comprising:

12. The temperature inside the cylinder is between room temperature (25°C) and 140°C, The temperature inside the nozzle is 100°C or higher and 140°C or lower, The injection molding method according to claim 11, wherein the temperature inside the cavity is 120°C or higher and 180°C or lower.