Dispersant and resin composition

Abstract

To provide a dispersant made of a polyether ester compound capable of dispersing inorganic powder suitably in a resin, thereby lowering viscosity of a resin composition, while suppressing elution of metals, and exhibiting superior heat resistance, and to provide a resin composition containing the dispersant.SOLUTION: A dispersant is composed of a polyether ester compound represented by formula (1). (In formula (1), R1 is a hydrocarbon group having 1 to 22 carbon atoms, AO is an oxyalkylene group having 2 to 4 carbon atoms, n is the average number of moles of added oxyalkylene units, which is 1 to 60, R2 is a phenolic hydroxyl group, and m is a number of 2 to 3.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dispersant comprising a polyether ester compound and a resin composition containing the dispersant. [Background technology]

[0002] The polarity, viscosity, reactivity, etc. of polyether ester compounds can be controlled by adjusting the type of oxyalkylene group contained as a constituent unit and the degree of polymerization thereof, thereby imparting properties such as flexibility and steric repulsion to the compounds. Thus, the compounds are used in a variety of applications, such as detergent compositions, water treatment agents, scale inhibitors, lubricants, plasticizers, and dispersants.

[0003] Among these applications, ester compounds of polyethers with aromatic carboxylic acids or phosphoric acids have been proposed as dispersants, and polyether ester compounds are used to exhibit steric repulsion properties in solvents and resins. Dispersants are also used in various industrial fields to disperse inorganic powders and the like in solvents. Examples of inorganic powders include ceramics and metal powders, and compositions containing inorganic powders are used in electronic components such as dielectric layers of multilayer ceramic capacitors, semiconductor substrates, sensors, and liquid crystal display elements.

[0004] Semiconductor encapsulants (hereinafter sometimes simply referred to as "encapsulants") contain a thermosetting resin that protects semiconductor chips from heat, ultraviolet light, moisture, impact, etc. and ensures electrical insulation. They consist of a resin composition in which an inorganic filler such as alumina is dispersed in a thermosetting resin such as an epoxy resin. Inorganic fillers such as alumina, which are commonly used in semiconductor encapsulants, have poor dispersibility in epoxy resins, causing the viscosity of the encapsulant to increase. High viscosity encapsulants can lead to insufficient filling during the encapsulation process, making reducing the viscosity of the encapsulant an important issue. Patent Document 1 reports that modifying the surface of a silica filler with a silane coupling agent to improve the dispersibility of the filler reduces the viscosity of the encapsulant.

[0005] On the other hand, in recent years, the particle size of fillers has become smaller, making it difficult to sufficiently modify the filler surface with a silane coupling agent, and therefore there is a limit to how much the silane coupling agent can improve dispersibility. Therefore, Patent Document 2 reports that the viscosity of the encapsulant can be reduced by improving the dispersibility of the filler using a dispersant containing a salt of at least one of an acidic phosphate chain ester and an acidic phosphite chain ester with a polyamine.

[0006] However, in recent years, due to further miniaturization and higher concentration of fillers, the amount of dispersant required to improve the dispersibility of the filler has increased. When encapsulation is performed using an encapsulant using the dispersant described in Patent Document 2, the acidic functional groups derived from the acidic chain phosphate ester and the acidic chain phosphite ester of the dispersant may cause the metal constituting the wiring on the substrate to elute, resulting in migration that causes a short circuit, and there is a risk of reducing the moisture resistance reliability of the semiconductor device.

[0007] Patent Document 3 reports that the moisture resistance reliability can be improved by using a dispersant having a basic functional group in combination with a silane coupling agent. However, as mentioned above, there is a limit to how much the dispersibility of the silane coupling agent can be improved, and it has been difficult to achieve both reduced viscosity and improved reliability.

[0008] In recent years, the market for power semiconductors, which can handle higher voltages and currents than conventional semiconductors, has been expanding. However, power semiconductors have higher operating temperatures than conventional semiconductors, and the encapsulating material for these semiconductors must have high heat resistance. If the additives used in the encapsulating material have low heat resistance, there is a risk that the high-temperature reliability of the semiconductor device will decrease.

[0009] Thus, in semiconductor encapsulation materials, in addition to the inorganic powder such as a filler being well dispersed in a thermosetting resin, it is required to suppress the elution of metals and to have good heat resistance, which is not limited to semiconductor encapsulation materials but may also be required in, for example, the various electronic components mentioned above. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent Publication No. 2021-55108 [Patent Document 2] Japanese Patent Publication No. 2022-7782 [Patent Document 3] Patent Publication No. 2021-24945 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a dispersant made of a polyether ester compound that can disperse inorganic powder well in a resin to reduce the viscosity of the resin composition, suppress metal elution, and have excellent heat resistance, and a resin composition containing the dispersant. [Means for solving the problem]

[0012] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by using a polyether ester compound having a specific structure. That is, the present invention relates to the following [1] and [2].

[0013] [1] A dispersant comprising a polyether ester compound represented by the following formula (1):

[0014] [ka]

[0015] (In formula (1), R 1 is a hydrocarbon group having 1 to 22 carbon atoms, AO is an oxyalkylene group having 2 to 4 carbon atoms, n is the average number of moles of oxyalkylene groups added and is a number from 1 to 60, and R 2 is a phenolic hydroxyl group, and m is a number from 2 to 3.

[0016] [2] A resin composition comprising an inorganic powder, a resin, and the dispersant according to [1] above, wherein the inorganic powder is dispersed in the resin, and the dispersant is contained in an amount of 0.1 to 50 parts by mass per 100 parts by mass of the inorganic powder. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a dispersant made of a polyether ester compound that can disperse inorganic powder well in a resin to reduce the viscosity of the resin composition, suppress metal elution, and have excellent heat resistance, and a resin composition containing the dispersant. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing a 1H NMR chart of polyether ester compound 1 (compound represented by the structural formula in FIG. 1) used in the dispersant according to an embodiment of the present invention obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in order.

[0020] (Polyether ester compound) The polyether ester compound used in the dispersant according to the embodiment of the present invention is a compound represented by the following formula (1).

[0021] [ka]

[0022] (In formula (1), R 1 is a hydrocarbon group having 1 to 22 carbon atoms, AO is an oxyalkylene group having 2 to 4 carbon atoms, n is the average number of moles of oxyalkylene groups added and is a number from 1 to 60, and R 2 is a phenolic hydroxyl group, and m is a number from 2 to 3.

[0023] In formula (1), R 1is any hydrocarbon group having 1 to 22 carbon atoms, preferably a linear or branched one, and examples thereof include linear saturated hydrocarbon groups such as methyl, ethyl, propyl, butyl, hexyl, heptyl, octyl, lauryl, myristyl, palmityl, stearyl, behenyl, and 1-dodecyl groups; branched saturated hydrocarbon groups such as isopropyl, isobutyl, t-butyl, isopentyl, isooctyl, 2-ethylhexyl, isononyl, 3,5,5-trimethylhexyl, isodecyl, isostearyl, 2-octyldecyl, 2-octyldodecyl, and 2-hexyldecyl groups; and unsaturated hydrocarbon groups such as allyl, (meth)acrylic, palmitoyl, oleyl, and linoleyl groups. These may be used alone or in combination of two or more. From the viewpoint of dispersibility, it is preferably a linear or branched saturated or unsaturated hydrocarbon group having 4 to 18 carbon atoms, and more preferably a linear or branched saturated hydrocarbon group having 4 to 18 carbon atoms.

[0024] In formula (1), AO is an oxyalkylene group having 2 to 4 carbon atoms, and the form of AO may be linear or branched, but branched is preferred when the carbon number is 3 to 4. AO may be one type or two or more types, and when two or more types of AO are used, the addition form may be random or block, but block is preferred from the viewpoint of dispersibility.

[0025] Examples of AO include oxyethylene groups (EO), oxypropylene groups (PO), and oxybutylene groups (BO). From the viewpoint of dispersibility, it is preferable to use one or two groups selected from oxyethylene groups and oxypropylene groups, and it is more preferable to use oxyethylene groups and oxypropylene groups. When two or more AOs are used in combination, the ratio can be appropriately determined depending on the type of AO, etc. For example, when EO is combined with PO or BO, the composition ratio of EO to PO or BO is preferably EO:PO (or BO) = 10:90 to 90:10 in mole fraction (mol %), more preferably 20:80 to 80:20.

[0026] In formula (1), n ​​is the average number of moles of oxyalkylene groups added, and is a number from 1 to 60. n can be appropriately set depending on the type of AO, etc., but from the viewpoint of dispersibility, n is preferably a number from 5 to 40, more preferably a number from 5 to 30, and even more preferably a number from 10 to 30.

[0027] In formula (1), R 2 means a phenolic hydroxyl group, i.e., -OH directly bonded to the benzene ring in formula (1). m represents the number of phenolic hydroxyl groups and is a number of 2 to 3. The phenolic hydroxyl groups in the polyether ester compound function as adsorption sites to inorganic powders. The more phenolic hydroxyl groups there are, the easier the compound is to adsorb to inorganic powders, so from the viewpoint of dispersibility, m=3 is preferred.

[0028] Next, an embodiment of a method for producing the polyether ester compound represented by formula (1) will be described.

[0029] The polyetherester compound represented by formula (1) can be obtained, for example, by a production method including a first step of producing a polyether and a second step of reacting the polyether obtained in the first step with an aromatic carboxylic acid having a phenolic hydroxyl group.

[0030] The first step will be described.

[0031] The polyether can be produced, for example, by adding an alkylene oxide to an alcohol having a linear or branched hydrocarbon group having 1 to 22 carbon atoms.

[0032] Examples of catalysts used in the addition reaction of alkylene oxides include alkali catalysts, such as oxides or hydroxides of alkali metals or alkaline earth metals, alcoholates, alkylamines such as triethylamine, and alkanolamines such as triethanolamine. In addition to the alkali catalysts described above, Lewis acid catalysts such as boron trifluoride and tin tetrachloride can also be used. The amount of catalyst used is generally 0.01 to 5.0% by mass based on the mass after completion of the addition reaction.

[0033] The addition reaction of alkylene oxide can be carried out, for example, in an atmosphere of an inert gas such as argon or nitrogen gas, at 50 to 200° C. and 0.02 to 1.0 MPa, by adding alkylene oxide while continuously applying pressure.

[0034] After the addition reaction is complete, if necessary, the pH of the reaction product is adjusted to about 6 to 7 under normal pressure and temperature, and water generated during the addition reaction is removed. Water removal can be carried out by a standard method, for example, at 80 to 120°C under reduced pressure. Furthermore, if necessary, salts contained in the reaction product are removed. Salt removal can be carried out, for example, by filtration.

[0035] Next, the second step will be described. In the second step, as described above, the polyether obtained in the first step is reacted with the predetermined aromatic carboxylic acid.

[0036] Examples of the aromatic carboxylic acid having a phenolic hydroxyl group used in the second step include 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, and gallic acid.

[0037] The reaction conditions can be appropriately determined depending on the polyether used, the above-mentioned predetermined aromatic carboxylic acid, etc., but the reaction temperature is generally 60 to 150° C., preferably 70 to 140° C., and more preferably 80 to 130° C. The reaction can be carried out under reduced pressure, for example, at −0.10 to −0.01 MPa (gauge pressure).

[0038] A catalyst may be used in the second step. Examples of the catalyst include acid catalysts, such as p-toluenesulfonic acid and methanesulfonic acid. The amount of catalyst used is generally 1.0 to 5.0% by mass based on the polyether.

[0039] After the reaction is complete, if necessary, the pH of the reaction product is adjusted to about 5 to 6 under normal pressure and temperature, and water generated during the reaction is removed. Water can be removed by a standard method, for example, at 80 to 120°C under reduced pressure. Furthermore, if necessary, salts contained in the reaction product are removed. Salts can be removed, for example, by filtration.

[0040] In both the first and second steps, the reaction may be carried out without a solvent or in a suitable dehydrated organic solvent. After completion of the reaction, the solvent used in the reaction may be removed by an operation such as distillation.

[0041] (dispersant) The dispersant according to an embodiment of the present invention is composed of the polyetherester compound described above. That is, the dispersant contains the polyetherester compound described above as an active ingredient for dispersing a desired inorganic powder, such as a filler, in a desired medium, such as a resin. The dispersant may be composed solely of the polyetherester compound, or may be composed of the compound and other additives that do not inhibit the function of the compound. However, it is preferable for the dispersant to be composed solely of the polyetherester compound. Examples of such additives include surfactants and antioxidants. The content of the additives can be determined as appropriate.

[0042] (Resin composition) The resin composition according to an embodiment of the present invention contains a resin, an inorganic powder, and the dispersant described above. The inorganic powder is dispersed in the resin. The polyether ester compound constituting the dispersant is thought to contribute to the dispersibility, preferably uniform dispersibility, of the inorganic powder in the resin. The content of the dispersant can be determined appropriately depending on the type of inorganic powder and the polyether ester compound contained in the dispersant, but it is preferable that the dispersant contains 0.1 to 50 parts by mass of the polyether ester compound per 100 parts by mass of the inorganic powder.

[0043] Usable inorganic powders can be appropriately selected depending on the application, etc., and examples include ceramic powders such as alumina, fused silica, and titanium oxide, metal powders such as silver, copper, and nickel, and carbon powders such as carbon black and carbon nanotubes. In the case of semiconductor sealing applications, ceramic powders such as alumina and fused silica are used as inorganic fillers. The content of the inorganic powder in the entire resin composition is preferably 60 to 98 mass%.

[0044] Usable resins can be appropriately selected depending on the application. Examples include epoxy resins, acrylic resins, butyral resins, and polyimide resins, with epoxy resins being preferred. Examples of epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, biphenyl epoxy resins, and biphenyl aralkyl epoxy resins. The resin content is preferably 10 to 50 parts by mass per 100 parts by mass of the inorganic powder.

[0045] In addition to the above-described components, the resin composition according to the embodiment may contain other additives to the extent that they do not impair the functions of the resin, dispersant, and inorganic powder. Examples of such additives include curing agents, curing accelerators, antioxidants, flame retardants, colorants, and plasticizers.

[0046] When an epoxy resin is used as the resin, examples of the curing agent include phenolic resins such as biphenyl novolac type phenolic resins, amines such as ethylenediamine, and acid anhydrides such as trimellitic anhydride.

[0047] The properties of the resin composition are determined appropriately depending on the composition of the components contained therein, but it is generally a paste.

[0048] The resin composition according to the embodiment can be prepared by a known method. For example, a method can be used in which a dispersant, a resin, an inorganic powder, and optional additives are added to a container, and then the mixture is dispersed at room temperature or under heat. The order in which the components are added is not particularly limited. Known dispersers can be used as dispersion equipment for the dispersion treatment. For example, a roll mill, a ball mill, a bead mill, a sand mill, a homogenizer, a disperser, a planetary centrifugal mixer, etc. can be used.

[0049] Because the resin composition contains the aforementioned polyetherester compound as an active ingredient of the dispersant, when used, for example, as a semiconductor encapsulant, (i) inorganic powders such as inorganic fillers are well dispersed in the resin, effectively suppressing an increase in the viscosity of the resin composition, and (ii) the excellent low metal elution and heat resistance of the polyetherester compound effectively suppress a decrease in the moisture resistance and high-temperature reliability of a semiconductor device caused by elution of metals in wiring on a substrate. Thus, the resin composition is suitable for use as a semiconductor encapsulant. The dispersibility of inorganic powders such as inorganic fillers in a resin using a dispersant made of a specific polyetherester compound, as well as the elution and heat resistance of metals such as copper, of the dispersant can be evaluated, for example, by the method described in the Examples section below. [Example]

[0050] Next, the embodiment of the present invention will be described in more detail based on examples.

[0051] (Identification of Polyetherester Compounds 1 to 8) The polyether ester compounds 1 to 8 obtained in Examples 1 to 6 and Comparative Examples 1 and 2 described below were identified by proton nuclear magnetic resonance spectroscopy ( 1 1 H NMR was used. 1 The measurement conditions for H NMR are as follows: Equipment: JNM-ECA-600 manufactured by JEOL Ltd. Solvent: deuterated dimethyl sulfoxide Temperature: 25℃ Frequency: 400MHz Accumulation count: 64

[0052] Example 1: Synthesis of polyetherester compound 1 A 5-liter stainless steel pressure vessel equipped with a stirrer, pressure gauge, thermometer, safety valve, gas inlet, exhaust pipe, cooling coil, and steam jacket was charged with 288 g (2 mol) of 3,5,5-trimethyl-1-hexanol (trade name: Nonanol, manufactured by KH Neochem Co., Ltd.) and 6 g of potassium hydroxide. After purging with nitrogen, the vessel was heated to 120 °C with stirring. While stirring, 581 g (10 mol) of propylene oxide was added from a separate pressure vessel through the gas inlet at 120 °C and 0.05 to 0.50 MPa (gauge pressure) while pressurizing with nitrogen gas. After addition, the reaction was continued under the same conditions until the internal pressure became constant. Next, 1057 g (24 mol) of ethylene oxide was added using the method described above, and after addition, the reaction was continued under the same conditions until the internal pressure became constant. The reaction product was then removed from the pressure vessel, neutralized with hydrochloric acid to a pH of 6 to 7, and subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. Finally, the salt was removed by filtration to obtain a polyether (the first step).

[0053] Next, 250 g (0.26 mol) of the polyether obtained in the first step, 47.7 g (0.22 mol) of gallic acid monohydrate (Wako Pure Chemical Industries, Ltd.), and 6.2 g (0.065 mol) of methanesulfonic acid were placed in a 0.5-liter glass reaction vessel equipped with a stirrer, thermometer, and gas inlet tube, and reacted at 120°C for 10 hours under reduced pressure of -0.08 MPa (gauge pressure) or less. The mixture was neutralized with sodium bicarbonate to a pH of 5-6, and then subjected to reduced pressure treatment at 100°C for 1 hour to remove the water content. Finally, the salt was removed by filtration to obtain polyetherester compound 1 (the second step).

[0054] The obtained polyetherester compound 1 was identified by the measurement method described above. From the chart shown in Figure 1, it was confirmed that polyetherester compound 1 was a polyetherester compound represented by formula (1) and had the structure shown in Table 1, based on the peaks A (δ 0.87 ppm), B (δ 1.03 ppm), C (δ 1.22 ppm), D (δ 1.33 ppm), E (δ 1.45 ppm), F (δ 3.15-3.71 ppm), G (δ 4.27 ppm), and H (δ 6.95 ppm). Polyetherester compound 1 was used as dispersant 1 and was evaluated as described below.

[0055] Example 2: Synthesis of polyetherester compound 2 In the first step, a polyether was obtained in the same manner as in Example 1, except that the amount of propylene oxide was 1569 g (27 mol) and the amount of ethylene oxide was 1188 g (27 mol). Next, 250 g (0.16 mol) of the polyether obtained in the first step, 25.7 g (0.14 mol) of gallic acid monohydrate (Wako Pure Chemical Industries, Ltd.), and 3.9 g (0.041 mol) of methanesulfonic acid were charged into a 0.5-liter glass reaction vessel equipped with a stirrer, thermometer, and gas inlet tube, and the mixture was reacted at 120°C for 10 hours under reduced pressure of -0.08 MPa (gauge pressure) or less. The mixture was neutralized with sodium bicarbonate to a pH of 5 to 6, and then subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. Finally, the salt was removed by filtration to obtain polyetherester compound 2 (the second step). Identification was performed in the same manner as in Example 1, and it was confirmed that polyetherester compound 2 was a polyetherester compound represented by formula (1), and its structure was as shown in Table 1. Polyetherester compound 2 was used as dispersant 2 for the evaluation described below.

[0056] (Example 3: Synthesis of polyetherester compound 3) A 5-liter stainless steel pressure vessel equipped with a stirrer, pressure gauge, thermometer, safety valve, gas inlet, exhaust, cooling coil, and steam jacket was charged with 288 g (2 mol) of 3,5,5-trimethyl-1-hexanol (trade name: Nonanol, manufactured by KH Neochem Co., Ltd.) and 6 g of potassium hydroxide. After purging with nitrogen, the mixture was heated to 120 °C with stirring. While stirring, 1408 g (32 mol) of ethylene oxide was added from a separate pressure vessel at 120 °C and 0.05 to 0.50 MPa (gauge pressure). After the addition was completed, the reaction mixture was allowed to react under the same conditions until the internal pressure became constant. The reaction mixture was then removed from the pressure vessel and neutralized with hydrochloric acid to a pH of 6 to 7. The reaction mixture was then subjected to reduced pressure at 100 °C for 1 hour to remove the water content. Finally, the salt was removed by filtration to obtain the polyether (first step).

[0057] Next, 250 g (0.29 mol) of the polyether obtained in the first step, 46.2 g (0.25 mol) of gallic acid monohydrate (Wako Pure Chemical Industries, Ltd.), and 7.1 g (0.074 mol) of methanesulfonic acid were placed in a 0.5-liter glass reaction vessel equipped with a stirrer, thermometer, and gas inlet tube, and the mixture was reacted at 120°C for 10 hours under reduced pressure of -0.08 MPa (gauge pressure) or less. The mixture was neutralized with sodium bicarbonate to a pH of 5 to 6, and then subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. Finally, the salt was removed by filtration to obtain polyetherester compound 3 (the second step). Identification was performed in the same manner as in Example 1, and it was confirmed that polyetherester compound 3 was a polyetherester compound represented by formula (1), and its structure was as shown in Table 1. Polyetherester compound 3 was used as dispersant 3 for the evaluation described below.

[0058] Example 4: Synthesis of polyetherester compound 4 In the first step, a polyether was obtained in the same manner as in Example 3, except that 288 g (2 mol) of 3,5,5-trimethyl-1-hexanol (trade name: Nonanol, manufactured by KH Neochem Co., Ltd.) was replaced with 316.6 g (2 mol) of isodecyl alcohol.

[0059] Next, 250 g (0.29 mol) of the polyether obtained in the first step, 45.4 g (0.24 mol) of gallic acid monohydrate (Wako Pure Chemical Industries, Ltd.), and 6.9 g (0.072 mol) of methanesulfonic acid were charged into a 0.5-liter glass reaction vessel equipped with a stirrer, thermometer, and gas inlet tube, and the mixture was reacted at 120°C for 10 hours under reduced pressure of -0.08 MPa (gauge pressure) or less. The mixture was neutralized with sodium bicarbonate to a pH of 5 to 6, and then subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. Finally, the salt was removed by filtration to obtain 300 g of polyetherester compound 4 (the second step). Identification was performed in the same manner as in Example 1, and it was confirmed that polyetherester compound 4 was a polyetherester compound represented by formula (1), and its structure was as shown in Table 1. Polyetherester compound 4 was used as dispersant 4 for the evaluation described below.

[0060] Example 5: Synthesis of polyetherester compound 5 In the first step, a polyether was obtained in the same manner as in Example 1. Next, 250 g (0.26 mol) of the polyether obtained in the first step, 33.3 g (0.22 mol) of 3,4-dihydroxybenzoic acid, and 6.2 g (0.065 mol) of methanesulfonic acid were placed in a 0.5-liter glass reaction vessel equipped with a stirrer, thermometer, and gas inlet tube, and the mixture was reacted at 120°C for 10 hours under reduced pressure of -0.08 MPa (gauge pressure) or less. The mixture was neutralized with sodium bicarbonate to a pH of 5 to 6, and then subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. Finally, the salt was removed by filtration to obtain polyetherester compound 5 (the second step). Identification was performed in the same manner as in Example 1, and it was confirmed that polyetherester compound 5 was a polyetherester compound represented by formula (1), and its structure was as shown in Table 1. Polyetherester compound 5 was used as dispersant 5 for the evaluation described below.

[0061] (Example 6: Synthesis of polyetherester compound 6) In the first step, a polyether was obtained in the same manner as in Example 1, except that 288 g (2 mol) of 3,5,5-trimethyl-1-hexanol (trade name: Nonanol, manufactured by KH Neochem Co., Ltd.) was replaced with 372.7 g (2 mol) of 1-dodecanol.

[0062] Next, 250 g (0.25 mol) of the polyether obtained in the first step, 39.0 g (0.21 mol) of gallic acid monohydrate (Wako Pure Chemical Industries, Ltd.), and 6.0 g (0.062 mol) of methanesulfonic acid were charged into a 0.5-liter glass reaction vessel equipped with a stirrer, thermometer, and gas inlet tube, and the mixture was reacted at 120°C for 10 hours under reduced pressure of -0.08 MPa (gauge pressure) or less. The mixture was neutralized with sodium bicarbonate to a pH of 5 to 6, and then subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. Finally, the salt was removed by filtration to obtain polyetherester compound 6 (the second step). Identification was performed in the same manner as in Example 1, and it was confirmed that polyetherester compound 6 was a polyetherester compound represented by formula (1), and its structure was as shown in Table 1. Polyetherester compound 6 was used as dispersant 6 for the evaluation described below.

[0063] (Comparative Example 1: Synthesis of Polyetherester Compound 7) In the first step, a polyether was obtained in the same manner as in Example 1. Next, 250 g (0.26 mol) of the polyether obtained in the first step, 29.9 g (0.22 mol) of 4-hydroxybenzoic acid, and 6.2 g (0.065 mol) of methanesulfonic acid were placed in a 0.5-liter glass reaction vessel equipped with a stirrer, thermometer, and gas inlet tube, and the mixture was reacted at 120°C for 10 hours under reduced pressure of -0.08 MPa (gauge pressure) or less. The mixture was neutralized with sodium bicarbonate to a pH of 5 to 6, and then subjected to reduced pressure treatment at 100°C for 1 hour to remove the contained water. Finally, the salt was removed by filtration to obtain polyetherester compound 7 (the second step). Identification was performed in the same manner as in Example 1, and its composition was confirmed to be as shown in Table 1. Polyetherester compound 7 was used as dispersant 7 and evaluated as described below.

[0064] (Comparative Example 2: Synthesis of Polyetherester Compound 8) In the first step, the polyether was obtained in the same manner as in Example 2. Next, 250 g (0.16 mol) of the polyether obtained in the first step and 24.3 g (0.16 mol) of phthalic anhydride (Kanto Chemical Co., Ltd.) were charged into a 0.5-liter glass reaction vessel equipped with a stirrer, a thermometer, and a gas inlet tube, and the mixture was reacted at 120°C for 4 hours. The reaction was terminated after confirming that 98% or more of the acid anhydride had been half-esterified by measuring the acid value. Polyetherester compound 8 was thus obtained. Identification was performed in the same manner as in Example 1, and it was confirmed that polyetherester compound 8 was represented by the following formula (2). Polyetherester compound 8 was used as dispersant 8 and evaluated as described below.

[0065] [ka]

[0066] (Dispersibility evaluation) Resin compositions were prepared as follows using the polyetherester compounds (dispersants) 1 to 8 obtained in Examples 1 to 6 and Comparative Examples 1 and 2. 2 g of inorganic powder (alumina, manufactured by Resonac Corporation, product name: AL-43-L), 0.494 g of epoxy resin (manufactured by Nippon Kayaku Co., Ltd., product name: NC-3000-L) as a resin, 0.363 g of phenolic resin (manufactured by Nippon Kayaku Co., Ltd., product name: KAYAHARD GPH-65) as a curing agent, and 0.02 g of dispersant were weighed into a 50 mL screw tube and kneaded using a spatula in an oil bath at 100°C. The viscosity of the resulting resin compositions was measured at a temperature of 90°C and a shear rate of 1 (1 / s) using a dynamic viscoelasticity analyzer (Paar Physica MCR-300, manufactured by Anton Paar). The measurement results were evaluated according to the following criteria. ◎: Shear viscosity is less than 200 Pa·s ○: Shear viscosity is 200 Pa·s or more and less than 500 Pa·s ×: Shear viscosity is 500 Pa·s or more

[0067] (Evaluation of copper elution) A 10% (isopropanol / water) solution of each of the polyether ester compounds (dispersants) 1 to 8 obtained in Examples 1 to 6 and Comparative Examples 1 and 2 was prepared, and a copper plate cut to a size of 1 x 2 cm was immersed in the solution and allowed to stand at 80°C for 18 hours. The copper plate was removed, washed, and weighed. The amount of copper eluted was calculated by [(weight of copper plate before immersion) - (weight of copper plate after immersion)] / (weight of copper plate before immersion) x 100, and evaluated according to the following criteria. ◎: The amount of elution is less than 0.15% ○: The amount of elution is 0.15% or more and less than 0.3% ×: The amount of elution is 0.3% or more

[0068] (Heat resistance evaluation) The weight loss rate of each of the polyether ester compounds (dispersants) 1 to 8 obtained in Examples 1 to 6 and Comparative Examples 1 and 2 was measured by thermogravimetry (TG) when they were held in air at 200°C for 2 hours. The weight loss rate was calculated from (weight loss (g) / initial weight (g)) x 100 and evaluated according to the following criteria. ◎: Weight loss rate is less than 15% ○: Weight loss rate is 15% or more and less than 30% ×: Weight loss rate is 30% or more

[0069] The evaluation results are shown in Table 2. In Table 2, the upper column for each evaluation item shows the measured value, and the units are as described above.

[0070] [Table 1]

[0071] [Table 2]

[0072] Dispersants 1 to 6, which are composed of polyether ester compounds 1 to 6 obtained in Examples 1 to 6, have excellent low copper elution properties and heat resistance, and are found to reduce the shear viscosity of the resin composition more than when dispersant 7, which is composed of polyether ester compound 7 in Comparative Example 1, is used. On the other hand, Dispersant 7 made of polyetherester compound 7 obtained in Comparative Example 1 is excellent in low copper elution and heat resistance, but is only slightly effective in reducing the shear viscosity of the resin composition. Dispersant 8 made of polyetherester compound 8 obtained in Comparative Example 2 reduces the shear viscosity of the resin composition, but is inferior in low copper elution and heat resistance. The evaluation results of the examples and comparative examples show that dispersants made of specific polyether ester compounds have excellent low copper elution properties and heat resistance, and can reduce the shear viscosity of resin compositions, and that these dispersants are effective as components of resin compositions containing inorganic powders. Furthermore, it is also found that resin compositions containing dispersants made of specific polyether ester compounds are suitable for use as semiconductor encapsulants.

Claims

1. A dispersant comprising a polyether ester compound represented by the following formula (1): 【Chemical 1】 (In formula (1), R １ is a hydrocarbon group having 1 to 22 carbon atoms, AO is an oxyalkylene group having 2 to 4 carbon atoms, n is the average number of moles of oxyalkylene groups added and is a number from 1 to 60, and R ２ is a phenolic hydroxyl group, and m is a number from 2 to 3.

2. A resin composition comprising an inorganic powder, a resin, and the dispersant according to claim 1, wherein the inorganic powder is dispersed in the resin, and the dispersant is contained in an amount of 0.1 to 50 parts by mass per 100 parts by mass of the inorganic powder.

Images