Curable resin composition and cured product

Abstract

To provide a curable resin composition and a cured product that can improve the mechanical properties and electrical properties (insulating properties) of the cured product. [Solution] The curable resin composition contains an epoxy resin and a novolac-type phenolic resin. The novolac-type phenolic resin contains a novolac-type phenolic resin modified with lignins. The lignins contain lignin modified with polyethylene glycol.

Description

[Technical Field]

[0001] This invention relates to curable resin compositions and cured products. [Background technology]

[0002] Conventionally, epoxy resin compositions are known as curable resin compositions. Epoxy resin compositions, for example, contain novolac-type epoxy resin and phenolic resin. Epoxy resin compositions harden upon heating, producing cured products. These cured products are used in various industrial fields. For example, cured products are used as semiconductor encapsulants.

[0003] More specifically, the following epoxy resin composition has been proposed as a curable resin composition. That is, the epoxy resin composition contains an o-cresol novolac type epoxy resin (epoxy resin A), a phenol novolac resin (phenol resin-based curing agent A), molten silica powder, an inorganic flame retardant, a silane coupling agent, a mold release agent, a curing accelerator, and a coloring agent (see, for example, Patent Document 1 (Example 3)). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-281623 [Overview of the project] [Problems that the invention aims to solve]

[0005] On the other hand, various industrial fields require improved mechanical properties of cured products. Furthermore, depending on the application, improved electrical properties (insulation properties) of cured products may also be required.

[0006] The present invention relates to a curable resin composition and a cured product that can improve the mechanical properties and electrical properties (insulating properties) of the cured product. [Means for solving the problem]

[0007] The present invention [1] is a curable resin composition containing an epoxy resin and a novolac-type phenol resin, wherein the novolac-type phenol resin contains a novolac-type phenol resin modified with lignins, and the lignins contain a lignin modified with polyethylene glycol. The curable resin composition is included.

[0008] The present invention [2] includes the curable resin composition according to the above [1], wherein the polyethylene glycol has a number average molecular weight of 200 or more and 600 or less.

[0009] The present invention [3] further includes the curable resin composition according to the above [1] or [2], which further contains silica.

[0010] The present invention [4] includes the curable resin composition according to the above [3], wherein the number average molecular weight x of the polyethylene glycol and the volume content y (volume%) of the silica relative to the total amount of the epoxy resin, the novolac-type phenol resin, and the silica satisfy the following formula.

[0011] 7.0≦[x / y]≦11.0

[0012] The present invention [5] includes a cured product of the curable resin composition according to any one of the above [1] to [4]. Effects of the Invention

[0013] The curable resin composition of the present invention contains an epoxy resin and a novolac-type phenol resin, and the novolac-type phenol resin is modified with lignins. The lignins contain a lignin modified with polyethylene glycol. Therefore, according to the curable resin composition of the present invention, the mechanical properties and electrical properties (insulation properties) of the cured product can be improved.

[0014] The cured product of the present invention is a cured product of the above-described curable resin composition. Therefore, the cured product of the present invention has excellent mechanical properties and electrical properties (insulating properties). [Modes for carrying out the invention]

[0015] 1. Curable resin composition The curable resin composition is a thermosetting resin composition that hardens (crosslinks) upon heat, as will be described in more detail later. The curable resin composition contains epoxy resin and novolac-type phenolic resin as essential components.

[0016] (1) Epoxy resin Epoxy resins contain at least one epoxy group. Examples of epoxy resins include novolac-type epoxy resins, bisphenol-type epoxy resins, aliphatic-type epoxy resins, alicyclic epoxy resins, hydrogenated bisphenol-type epoxy resins, and amine-type epoxy resins. These can be used individually or in combination of two or more types. From the viewpoint of the mechanical properties and electrical properties (insulating properties (hereinafter the same)) of the cured product (described later), preferred epoxy resins are novolac-type epoxy resins and bisphenol-type epoxy resins, and more preferably, novolac-type epoxy resins. Examples of novolac-type epoxy resins include phenol novolac-type epoxy resins, o-cresol novolac-type epoxy resins, m-cresol novolac-type epoxy resins, p-cresol novolac-type epoxy resins, and brominated novolac-type epoxy resins. Examples of bisphenol-type epoxy resins include bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and brominated bisphenol A-type epoxy resins. These can be used individually or in combination of two or more types. From the viewpoint of the mechanical and electrical properties of the cured product (described later), novolac-type epoxy resins are more preferably used as epoxy resins, and o-cresol novolac-type epoxy resins are particularly preferred.

[0017] [Physical properties] The epoxy equivalent of the epoxy resin is, for example, 100 g / eq to 1000 g / eq, preferably 150 g / eq to 600 g / eq, and more preferably 200 g / eq to 300 g / eq. The epoxy equivalent is measured in accordance with JIS K 7236 (2009).

[0018] The density of epoxy resin is, for example, 1.0 g / cm³. 3 More than 1.5g / cm 3 Preferably, 1.0 g / cm³ 3 More than 1.3g / cm 3 More preferably, 1.1 g / cm³ 3 More than 1.2g / cm 3 The following applies. The density is measured using a commercially available density measurement kit, in accordance with the examples described later (the same applies hereafter).

[0019] Details regarding the epoxy resin content will be provided later.

[0020] (2) Novolac-type phenolic resin Novolac-type phenolic resin contains, as an essential component, a novolac-type phenolic resin modified with lignins (hereinafter referred to as lignin-modified novolac-type phenolic resin).

[0021] [Lignin-modified novolac-type phenolic resin] Lignin-modified novolac-type phenolic resins contain, for example, reaction products of lignins, phenols, and aldehydes. Preferably, the lignin-modified novolac-type phenolic resin consists of reaction products of lignins, phenols, and aldehydes.

[0022] [Lignins] Lignins contain, as an essential component, lignin modified with polyethylene glycol (PEG) (hereinafter sometimes referred to as PEG-modified lignin). Lignins preferably consist of PEG-modified lignin.

[0023] In PEG-modified lignin, the lignin is a high-molecular-weight phenolic compound, and for example, it contains polymers of monolignol (also known as lignin monomer). Monolignols include, for example, coniferyl alcohol, sinapyr alcohol, and p-coumaryl alcohol. The average molecular weight (mass-based proportional value) of monolignol is, for example, 150 to 250 (preferably 200). More specifically, examples of lignin include natural lignin (unmodified lignin) and lignin derivatives.

[0024] Natural lignin is lignin that exists as a natural product. Natural lignin is found, for example, in plants in general. Natural lignin includes, for example, a lignin basic skeleton, and preferably consists of a lignin basic skeleton. Examples of lignin basic skeletons include guaiacyllignin (G type), syringyllignin (S type), and p-hydroxyphenyllignin (H type). The average molecular weight (mass-based proportional value) of the lignin basic skeleton is, for example, 150 to 250 (preferably 200).

[0025] More specifically, natural lignin is classified, for example, by the type of plant from which it is derived. Examples of natural lignin include lignin derived from woody plants and lignin derived from herbaceous plants. Examples of lignin derived from woody plants include coniferous lignin and broadleaf lignin, with coniferous lignin being preferred. An example of coniferous lignin is cedar lignin. Examples of lignin derived from herbaceous plants include wheat straw lignin, rice straw lignin, corn stover lignin, and bamboo lignin. These can be used individually or in combination of two or more types.

[0026] From the viewpoint of homogeneity, woody plant-derived lignin is preferred, coniferous tree-derived lignin is preferred, and even more preferred is cedar lignin.

[0027] From the viewpoint of the mechanical and electrical properties of the cured product (described later), herbaceous plant-derived lignin is preferred, more preferably corn stover lignin and bamboo lignin, and even more preferably bamboo lignin.

[0028] Lignin derivatives are derivatives of the natural lignins mentioned above, and specifically include, for example, alkali lignin (soda lignin), sulfite lignin, and kraft lignin.

[0029] Lignin derivatives can be obtained, for example, by treating plants containing natural lignin using industrially known methods. In other words, industrially obtained lignin (i.e., industrial lignin) can be considered a lignin derivative.

[0030] More specifically, lignin derivatives are found in the solution components (black liquor) obtained when pulp is produced from plants. Methods for producing pulp from plants include the alkaline process (soda process), the sulfurous acid process, and the Kraft process. More specifically, the solution components (black liquor) discharged in the alkaline process (soda process) contain alkaline lignin (soda lignin). The solution components (black liquor) discharged in the sulfurous acid process contain sulfite lignin. The solution components (black liquor) discharged in the Kraft process contain Kraft lignin. Furthermore, the methods for obtaining lignin derivatives are not limited to those described above. For example, lignin derivatives such as exploded lignin can be obtained by treating plants with an explosion process.

[0031] Lignin (natural lignin and / or lignin derivatives (hereinafter the same)) can be used alone or in combination of two or more types. Lignin derivatives are preferred as the lignin.

[0032] In PEG-modified lignin, polyethylene glycol (PEG) modifies the lignin and improves the mechanical and electrical properties of the cured product (described later).

[0033] From the viewpoint of the mechanical and electrical properties of the cured product (described later), the number-average molecular weight of polyethylene glycol is, for example, 100 or more, preferably 150 or more, more preferably 200 or more, even more preferably 300 or more, and particularly preferably 400 or more. Alternatively, the number-average molecular weight of polyethylene glycol is, for example, 1000 or less, preferably 800 or less, more preferably 600 or less, and even more preferably 500 or less.

[0034] In other words, from the viewpoint of the mechanical and electrical properties of the cured product (described later), the number-average molecular weight of polyethylene glycol is, for example, 100 to 1000, preferably 150 to 800, more preferably 200 to 600, even more preferably 300 to 500, and particularly preferably 400 to 500. The number-average molecular weight can be determined as the polyethylene glycol-equivalent molecular weight by a known gel permeation chromatography method.

[0035] PEG-modified lignin is produced, for example, in accordance with the method described in Japanese Patent Publication No. 2017-197517. In this method, for example, plant materials that will be used as raw materials for lignin (e.g., woody plants and herbaceous plants) are pulverized using polyethylene glycol.

[0036] The pulping method is not particularly limited, but for example, plant material that will be used as a raw material for lignin, polyethylene glycol, and an inorganic acid as an acid catalyst (e.g., hydrochloric acid and sulfuric acid) are mixed and reacted.

[0037] The proportion of polyethylene glycol used is, for example, 200 parts by mass or more and 1000 parts by mass or less, preferably 300 parts by mass or more and 600 parts by mass or less, per 100 parts by mass of plant material that serves as the raw material for lignin.

[0038] Furthermore, the blending ratio of inorganic acid (calculated at 100%) is, for example, 0.1 parts by mass or more and 2 parts by mass or less, preferably 0.2 parts by mass or more and 1 part by mass or less, per 100 parts by mass of polyethylene glycol.

[0039] Furthermore, the reaction conditions include being under atmospheric pressure. The reaction temperature is, for example, 120°C to 180°C, preferably 130°C to 150°C. The reaction time is, for example, 60 minutes to 240 minutes, preferably 60 minutes to 120 minutes.

[0040] Furthermore, after the reaction is complete, alkali is added to the reaction solution in an appropriate proportion to adjust the pH. Examples of alkalis include ammonia, sodium hydroxide, and potassium hydroxide. This extracts the PEG-modified lignin into the solution. The adjusted pH is, for example, 8 to 14, preferably 10 to 14, and more preferably 10.5 to 14.

[0041] By the method described above, pulp is obtained as the solid component, and PEG-modified lignin is obtained as the solution component.

[0042] Next, in this method, the solid component (pulp) is separated from the reaction product by a known separation method, and the solution component is recovered. Examples of separation methods include filtration, pressing, and centrifugation.

[0043] Furthermore, this method allows for the washing of the solid components (pulp) and the recovery of the solution (PEG-modified lignin) impregnated into the solid components, if necessary.

[0044] Subsequently, in this method, inorganic acids (e.g., hydrochloric acid and sulfuric acid) are added to the solution components to adjust the pH and precipitate PEG-modified lignin. The adjusted pH is, for example, between 1.5 and 5. The resulting precipitate is then recovered by a known method. Through these steps, PEG-modified lignin can be obtained as a solid component.

[0045] Lignins may, if necessary, contain lignins other than PEG-modified lignin (hereinafter sometimes referred to as "other lignins") as optional components. Examples of other lignins include the above-mentioned lignin that has not been modified with polyethylene glycol (natural lignin and / or lignin derivatives (hereinafter the same)).

[0046] Furthermore, other lignins may be denatured by acid. That is, other lignins include lignin denatured by acid (hereinafter sometimes referred to as acid-denatured lignin).

[0047] Acid-modified lignin is obtained by modifying the above-mentioned lignin with an acid. Examples of acids include carboxylic acids. In other words, carboxylic acid-modified lignin is preferred as acid-modified lignin.

[0048] Examples of carboxylic acids include saturated aliphatic carboxylic acids, unsaturated aliphatic carboxylic acids, and aromatic carboxylic acids. Examples of saturated aliphatic carboxylic acids include acetic acid, propionic acid, butyric acid, and lauric acid. Examples of unsaturated aliphatic carboxylic acids include acrylic acid, methacrylic acid, and linoleic acid. Examples of aromatic carboxylic acids include benzoic acid, 2-phenoxybenzoic acid, and 4-methylbenzoic acid. These can be used individually or in combination of two or more. Preferably, saturated aliphatic carboxylic acids are used as carboxylic acids, and more preferably, acetic acid. That is, preferably, saturated aliphatic carboxylic acid-modified lignin is used as acid-modified lignin, and more preferably, acetic acid-modified lignin is used.

[0049] The method for obtaining acid-modified lignin is not particularly limited and can be based on known methods. For example, plant materials that serve as raw materials for lignin (e.g., woody plants and herbaceous plants) are pulverized with the above-mentioned acid to modify the aliphatic hydroxyl groups in the lignin with the acid.

[0050] By the method described above, pulp is obtained as a solid component, and acid-modified lignin is obtained as a solution component.

[0051] Next, in this method, the solid component (pulp) is separated from the reaction product by a known separation method, and the solution component is recovered. Examples of separation methods include filtration, pressing, and centrifugation. In addition, if necessary, unreacted acid is removed from the solution component by a known method.

[0052] Subsequently, in this method, the solution components are concentrated and filtered, and the resulting solid is recovered by a known method. Through these steps, acid-modified lignin can be obtained as the solid.

[0053] Other types of lignin can be used alone or in combination of two or more.

[0054] The content of other lignins is set appropriately according to the purpose and application. From the viewpoint of the mechanical and electrical properties of the cured product (described later), for example, the content of other lignins is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 0% by mass, relative to the total amount of lignins (i.e., the total amount of PEG-modified lignin and other lignins).

[0055] In other words, from the viewpoint of the mechanical and electrical properties of the cured product (described later), the content of PEG-modified lignin is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, relative to the total amount of lignins (i.e., the total amount of PEG-modified lignin and other lignins). That is, from the viewpoint of the mechanical and electrical properties of the cured product (described later), the lignins are particularly preferably PEG-modified lignin.

[0056] [Phenols] Phenols are compounds having a phenol skeleton (excluding the lignins mentioned above). Examples of phenols include phenol and phenol derivatives (phenol-modified compounds). More specifically, examples of phenols include phenol, difunctional phenol derivatives, trifunctional phenol derivatives, and tetrafunctional phenol derivatives. Examples of difunctional phenol derivatives include o-cresol, p-cresol, p-tert-butylphenol, p-phenylphenol, p-cumylphenol, and p-nonylphenol. Examples of trifunctional phenol derivatives include m-cresol, resorcinol, and 3,5-xylenol. Examples of tetrafunctional phenol derivatives include bisphenol A and dihydroxydiphenylmethane. In addition, halogenated phenols are also included as phenol derivatives. Halogenated phenols are halogenated compounds of phenol or the above-mentioned phenol derivatives. Examples of halogens include chlorine and bromine. These phenols can be used individually or in combination of two or more types. Furthermore, the timing of the derivatization (modification) of phenol derivatives is not particularly limited. For example, the derivatization of phenol may occur before, after, or simultaneously with the reaction between phenols and aldehydes. From the viewpoint of the mechanical properties of the tire, phenol is a preferred example of the phenol.

[0057] [Aldehydes] Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, furfural, glyoxal, benzaldehyde, trioxane, and tetraoxane. Furthermore, some of the aldehydes may be substituted with furfuryl alcohol or the like. These aldehydes can be used individually or in combination of two or more. Preferably, the aldehydes are formaldehyde and paraformaldehyde, and more preferably, paraformaldehyde.

[0058] Furthermore, aldehydes can be used, for example, as an aqueous solution. In such cases, the concentration of the aldehydes is, for example, 10% by mass or more and 99% by mass or less, preferably 20% by mass or more and 95% by mass or less.

[0059] In addition, ketones can be used together with aldehydes. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, acetophenone, and diphenyl ketone. These ketones can be used alone or in combination of two or more. When ketones are used, the amount of ketones is, on a solid content basis, for example, 0.01 parts by mass to 200 parts by mass, preferably 1 part by mass to 100 parts by mass, per 100 parts by mass of aldehydes.

[0060] [Method for producing lignin-modified novolac-type phenolic resin] As described above, lignin-modified novolac-type phenolic resins are produced by the reaction of lignins, phenols, and aldehydes (and ketones added as needed (hereinafter the same)).

[0061] To react lignins, phenols, and aldehydes (and ketones added as needed (hereinafter the same)), for example, the lignins, phenols, and aldehydes are combined together or sequentially, and heated in the presence of an acid catalyst (described later).

[0062] In this reaction, the proportion of phenols is, for example, 30 parts by mass or more and 1000 parts by mass or less, preferably 50 parts by mass or more and 500 parts by mass or less, more preferably 100 parts by mass or more and 350 parts by mass or less, and even more preferably 130 parts by mass or more and 200 parts by mass or less, per 100 parts by mass of lignin.

[0063] In other words, the proportion of lignins to be blended is, for example, 10 parts by mass or more and 300 parts by mass or less, preferably 20 parts by mass or more and 200 parts by mass or less, more preferably 30 parts by mass or more and 100 parts by mass or less, and even more preferably 50 parts by mass or more and 75 parts by mass or less, per 100 parts by mass of phenols.

[0064] Furthermore, the proportion of aldehydes is, for example, 5 parts by mass or more and 35 parts by mass or less, preferably 10 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of phenols.

[0065] Furthermore, the proportion of aldehydes is, for example, 1.5 parts by mass or more and 350 parts by mass or less, preferably 3 parts by mass or more and 300 parts by mass or less, and more preferably 10 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of lignin.

[0066] Furthermore, an acid catalyst is added in this reaction. That is, each of the above components (lignins, phenols, and aldehydes) reacts under the influence of an acid catalyst.

[0067] Examples of acid catalysts include Lewis acids. Examples of Lewis acids include organic acids, inorganic acids, and metal salts. Examples of organic acids include carboxylic acid compounds, sulfonic acid compounds, and phosphoric acid compounds. Examples of carboxylic acid compounds include formic acid, acetic acid, and oxalic acid. Examples of sulfonic acid compounds include methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, cumenesulfonic acid, dinonylnaphthalene monosulfonic acid, and dinonylnaphthalenedisulfonic acid. Examples of phosphoric acid compounds include phosphoric acid esters. More specifically, examples of phosphoric acid esters include phosphoric acid esters having alkyl groups with 1 to 18 carbon atoms. Examples of phosphoric acid compounds include trimethyl phosphate, triethyl phosphate, monobutyl phosphate, dibutyl phosphate, tributyl phosphate, and trioctyl phosphate. Examples of inorganic acids include phosphoric acid, hydrochloric acid, sulfuric acid, and nitric acid. Examples of metal salts include zinc acetate, manganese acetate, calcium acetate, lead acetate, zinc borate, manganese borate, nickel borate, zinc naphthenate, lead naphthenate, cobalt naphthenate, zinc octoate, zinc benzoate, zinc oxide, and lead oxide. These acid catalysts can be used individually or in combination of two or more. Preferably, the acid catalyst is an organic acid, more preferably a carboxylic acid compound, and even more preferably oxalic acid.

[0068] The amount of acid catalyst added is, for example, 0.1 parts by mass to 10 parts by mass, preferably 0.3 parts by mass to 5 parts by mass, per 100 parts by mass of phenols.

[0069] The timing of adding the acid catalyst is not particularly limited. For example, the acid catalyst may be added beforehand to at least one of the lignins, phenols, and aldehydes. Alternatively, the acid catalyst may be added simultaneously with the blending of the lignins, phenols, and aldehydes. Furthermore, the acid catalyst may be added after the blending of the lignins, phenols, and aldehydes.

[0070] Further, in the reaction of lignins, phenols, and aldehydes, a solvent can be used. The solvent is not particularly limited as long as it is an inert solvent relative to lignins, phenols, and aldehydes, and a known solvent may be used. More specifically, examples of the solvent include water. The blending amount of the solvent is appropriately set according to the purpose and application.

[0071] Further, in the reaction of lignins, phenols, and aldehydes, the above respective components can be blended all at once for a collective reaction, or the above respective components can be blended sequentially for sequential reactions. Preferably, the above respective components are blended all at once for a collective reaction.

[0072] Examples of the reaction conditions include atmospheric pressure. The reaction temperature is, for example, 50°C to 200°C, preferably 80°C to 180°C. The reaction time is, for example, 1 hour to 20 hours, preferably 2 hours to 15 hours.

[0073] Through the above reaction, a novolac phenolic resin modified by lignins (lignin-modified novolac phenolic resin) is obtained as the reaction product of lignins, phenols, and aldehydes.

[0074] The phenolic hydroxyl group equivalent of the lignin-modified novolac phenolic resin is, for example, 100 g / eq to 1000 g / eq, preferably 100 g / eq to 800 g / eq, more preferably 150 g / eq to 500 g / eq. The phenolic hydroxyl group equivalent is calculated based on the charged amounts in accordance with the examples described later (the same applies hereinafter).

[0075] The density of the lignin-modified novolac phenolic resin is, for example, 1.0 g / cm 3 to 1.5 g / cm 3 or less, preferably 1.0 g / cm 3 to 1.3 g / cm 3 or less, more preferably 1.1 g / cm 3 to 1.2 g / cm3 The following applies:

[0076] [Lignin-free novolac type phenolic resin] Novolac-type phenolic resins may contain, as an optional component, novolac-type phenolic resins that have not been modified with lignins (hereinafter referred to as lignin-unmodified novolac-type phenolic resins).

[0077] Lignin-free novolac-type phenolic resins can be obtained, for example, by reacting the above-mentioned phenols and aldehydes in the presence of the above-mentioned acid catalyst using a known method.

[0078] The phenolic hydroxyl group equivalent of the lignin-unmodified novolac-type phenolic resin is, for example, 100 g / eq or more and 1000 g / eq or less, preferably 100 g / eq or more and 500 g / eq or less, and more preferably 150 g / eq or more and 300 g / eq or less.

[0079] The density of lignin-unmodified novolac-type phenolic resin is, for example, 1.0 g / cm³. 3 More than 1.5g / cm 3 Preferably, 1.0 g / cm³ 3 More than 1.3g / cm 3 More preferably, 1.1 g / cm³ 3 More than 1.2g / cm 3 The following applies:

[0080] The content of the lignin-free novolac-type phenolic resin is set appropriately within a range that does not hinder the excellent effects of the present invention. For example, the content of the lignin-free novolac-type phenolic resin is, for example, 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less, and particularly preferably 0% by mass, relative to the total amount of novolac-type phenolic resin. In other words, the content of the lignin-modified novolac-type phenolic resin is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and particularly preferably 100% by mass, relative to the total amount of novolac-type phenolic resin.

[0081] In other words, the novolac-type phenolic resin is, in particular, not to contain lignin-unmodified novolac-type phenolic resin, but to consist of a lignin-modified novolac-type phenolic resin.

[0082] [Physical properties] The phenolic hydroxyl group equivalent of the novolac-type phenolic resin (the total amount of both lignin-modified and lignin-unmodified novolac-type phenolic resins used in combination) is, for example, 100 g / eq or more and 1000 g / eq or less, preferably 100 g / eq or more and 800 g / eq or less, and more preferably 150 g / eq or more and 500 g / eq or less.

[0083] The density of novolac-type phenolic resin (the total amount when lignin-modified novolac-type phenolic resin and lignin-unmodified novolac-type phenolic resin are used in combination) is, for example, 1.0 g / cm³. 3 More than 1.5g / cm 3 Preferably, 1.0 g / cm³ 3 More than 1.3g / cm 3 More preferably, 1.1 g / cm³ 3 More than 1.2g / cm 3 The following applies:

[0084] Details regarding the content ratio of novolac-type phenolic resin will be described later.

[0085] (3) Additives The curable resin composition may contain additives as optional components. Examples of additives include curing accelerators, internal release agents, fillers, flame retardants, ion trapping agents, antioxidants, adhesion promoters, colorants, and coupling agents. These can be used individually or in combination of two or more. Preferably, the additives include curing accelerators, internal release agents, and fillers.

[0086] [Curing accelerator] The curing accelerator is not particularly limited and includes known curing accelerators. Specifically, examples of curing accelerators include imidazole compounds, phosphine compounds, and tertiary amine compounds. Examples of imidazole compounds include 2-ethyl-4-methylimidazole and its derivatives, and 1-cyanoethyl-2-ethyl-4-methylimidazole and its derivatives. Examples of phosphine compounds include triphenylphosphine (TPP) and its derivatives. Examples of tertiary amine compounds include benzyldimethylamine. These can be used alone or in combination of two or more. Preferably, the curing accelerator is an imidazole compound, and more preferably 2-ethyl-4-methylimidazole.

[0087] [Internal release agent] Examples of internal release agents include wax, stearic acid, stearic acid esters, and stearic acid amides. These can be used individually or in combination of two or more. Wax is preferably used as an internal release agent. Examples of waxes include carnauba wax, rice wax, and candelilla wax. These can be used individually or in combination of two or more. Rice wax is preferably used as a wax.

[0088] [Filler] Examples of fillers include inorganic fillers and organic fillers. Examples of inorganic fillers include silica, alumina, titania, talc, zinc oxide, magnesium oxide, zirconium oxide, aluminum hydroxide, and magnesium hydroxide. Examples of organic fillers include resin particles, rubber powder, wood powder, cork, and cashew dust. These can be used individually or in combination of two or more types.

[0089] From the viewpoint of the mechanical and electrical properties of the cured product (described later), inorganic fillers are preferred, and silica is preferred as the filler. In other words, from the viewpoint of the mechanical and electrical properties of the cured product (described later), the curable resin composition preferably contains inorganic fillers, and more preferably contains silica.

[0090] Examples of silica include natural silica, fused silica, and spherical silica. These can be used individually or in combination of two or more types. From the viewpoint of the mechanical and electrical properties of the cured product (described later), fused silica is preferred as the silica.

[0091] The density of silica is, for example, 2.0 g / cm³. 3 More than 3.0g / cm 3 Preferably, 2.2 g / cm³ 3 More than 2.5g / cm 3 The following applies:

[0092] [Addition method] The method and timing of adding the additive are not particularly limited. The additive may, for example, be added in advance to the epoxy resin and / or novolac-type phenolic resin. Alternatively, the additive may be blended together with the epoxy resin and the novolac-type phenolic resin when they are mixed. Alternatively, the additive may be added to the mixture after the epoxy resin and the novolac-type phenolic resin have been mixed. Preferably, the additive is blended together with the epoxy resin and the novolac-type phenolic resin when they are mixed.

[0093] Details regarding the proportion of additives will be provided later.

[0094] (4)Content ratio In a curable resin composition, the content ratio of epoxy resin, the content ratio of novolac-type phenolic resin, and the content ratio of additives are appropriately set according to the purpose and application. Each of these is described in detail below.

[0095] [Epoxy resin content] The epoxy resin content is, for example, 1% by mass or more and 99% by mass or less, preferably 5% by mass or more and 95% by mass or less, and more preferably 3% by mass or more and 30% by mass or less, relative to the total amount of the curable resin composition.

[0096] Furthermore, the epoxy resin content is, for example, 10 parts by mass or more and 90 parts by mass or less, preferably 20 parts by mass or more and 80 parts by mass or less, more preferably 30 parts by mass or more and 70 parts by mass or less, and even more preferably 50 parts by mass or more and 60 parts by mass or less, based on 100 parts by mass of the total amount of epoxy resin and novolac-type phenolic resin.

[0097] [Percentage of novolac-type phenolic resin content] The content of the novolac-type phenolic resin is, for example, 1% by mass or more and 99% by mass or less, preferably 5% by mass or more and 95% by mass or less, and more preferably 7% by mass or more and 30% by mass or less, based on the total amount of the curable resin composition.

[0098] Furthermore, the content ratio of the novolac-type phenolic resin is, for example, 10 parts by mass or more and 90 parts by mass or less, preferably 20 parts by mass or more and 80 parts by mass or less, more preferably 30 parts by mass or more and 70 parts by mass or less, and even more preferably 40 parts by mass or more and 50 parts by mass or less, based on 100 parts by mass of the total amount of epoxy resin and novolac-type phenolic resin.

[0099] Furthermore, the content ratio of the novolac-type phenolic resin is, for example, 10 parts by mass or more and 200 parts by mass or less, preferably 50 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of epoxy resin.

[0100] Furthermore, the content ratio of epoxy resin and novolac-type phenolic resin can be adjusted based on the equivalent ratio of epoxy groups in the epoxy resin to the equivalent amount of phenolic hydroxyl groups in the novolac-type phenolic resin (epoxy groups / phenolic hydroxyl groups).

[0101] More specifically, the equivalent ratio of epoxy groups of the epoxy resin to phenolic hydroxyl groups of the novolac-type phenolic resin (epoxy groups / phenolic hydroxyl groups) is, for example, 0.7 to 1.3, preferably 0.8 to 1.2, and more preferably 0.9 to 1.1. The equivalent ratio (epoxy groups / phenolic hydroxyl groups) is calculated based on the equivalent amount of phenolic hydroxyl groups of the novolac-type phenolic resin and the epoxy equivalent amount of the epoxy resin.

[0102] [Percentage of additives] When the curable resin composition contains additives, the proportion of the additives (the total amount if two or more additives are used in combination) is, for example, 0.1% by mass or more and 99% by mass or less, preferably 1% by mass or more and 95% by mass or less, and more preferably 10% by mass or more and 90% by mass or less, relative to the total amount of the curable resin composition.

[0103] Furthermore, the content ratio of the additive is, for example, 0.1 parts by mass or more and 2000 parts by mass or less, preferably 1 part by mass or more and 1000 parts by mass or less, more preferably 100 parts by mass or more and 800 parts by mass or less, and even more preferably 200 parts by mass or more and 600 parts by mass or less, based on 100 parts by mass of the total amount of epoxy resin and novolac-type phenolic resin.

[0104] Furthermore, the total amount of additives is, for example, 0.1 parts by mass or more and 2000 parts by mass or less, preferably 0.5 parts by mass or more and 1000 parts by mass or less, per 100 parts by mass of epoxy resin.

[0105] Furthermore, the proportion of additives is adjusted as appropriate depending on the type of additive. The proportions of curing accelerators, internal release agents, and fillers are described in detail below.

[0106] [Percentage of curing accelerator] If the curable resin composition contains a curing accelerator, the content of the curing accelerator is, for example, 0.01% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 1% by mass or less, relative to the total amount of the curable resin composition.

[0107] Furthermore, the content ratio of the curing accelerator is, for example, 0.01 parts by mass or more and 50 parts by mass or less, more preferably 0.1 parts by mass or more and 5 parts by mass or less, based on 100 parts by mass of the total amount of epoxy resin and novolac-type phenolic resin.

[0108] Furthermore, the content ratio of the curing accelerator is, for example, 0.1 parts by mass or more and 50 parts by mass or less, preferably 0.5 parts by mass or more and 10 parts by mass or less, per 100 parts by mass of epoxy resin.

[0109] [Internal mold release agent content] When the curable resin composition contains an internal release agent, the content of the internal release agent is, for example, 0.01% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 1% by mass or less, relative to the total amount of the curable resin composition.

[0110] Furthermore, the content ratio of the internal release agent is, for example, 0.01 parts by mass or more and 50 parts by mass or less, more preferably 0.1 parts by mass or more and 5 parts by mass or less, based on 100 parts by mass of the total amount of epoxy resin and novolac-type phenolic resin.

[0111] Furthermore, the content ratio of the internal release agent is, for example, 0.1 parts by mass or more and 50 parts by mass or less, preferably 0.5 parts by mass or more and 10 parts by mass or less, per 100 parts by mass of epoxy resin.

[0112] [Percentage of filler content] If the curable resin composition contains a filler, the filler content is, for example, 1% by mass or more and 99% by mass or less, preferably 10% by mass or more and 90% by mass or less, relative to the total amount of the curable resin composition.

[0113] Furthermore, the filler content is, for example, 0.1 parts by mass or more and 2000 parts by mass or less, preferably 1 part by mass or more and 1000 parts by mass or less, more preferably 100 parts by mass or more and 800 parts by mass or less, and even more preferably 200 parts by mass or more and 600 parts by mass or less, based on 100 parts by mass of the total amount of epoxy resin and novolac-type phenolic resin.

[0114] Furthermore, the filler content is, for example, 100 parts by mass or more and 2000 parts by mass or less, preferably 300 parts by mass or more and 1000 parts by mass or less, per 100 parts by mass of epoxy resin.

[0115] In particular, when the curable resin composition contains silica, the silica content is, for example, 1% by mass or more and 99% by mass or less, preferably 10% by mass or more and 90% by mass or less, relative to the total amount of the curable resin composition.

[0116] Furthermore, the silica content is, for example, 0.1 parts by mass or more and 2000 parts by mass or less, preferably 1 part by mass or more and 1000 parts by mass or less, more preferably 100 parts by mass or more and 800 parts by mass or less, and even more preferably 200 parts by mass or more and 600 parts by mass or less, based on 100 parts by mass of the total amount of epoxy resin and novolac-type phenolic resin.

[0117] Furthermore, the silica content is, for example, 100 parts by mass or more and 2000 parts by mass or less, preferably 300 parts by mass or more and 1000 parts by mass or less, per 100 parts by mass of epoxy resin.

[0118] Furthermore, the silica content may be adjusted on a volume basis.

[0119] More specifically, the volume content of silica relative to the total amount of epoxy resin, novolac-type phenolic resin, and silica is, for example, 10% by volume or more and 99% by volume or less, preferably 30% by volume or more and 90% by volume or less, more preferably 50% by volume or more and 80% by volume or less, even more preferably 50% by volume or more and 70% by volume or less, and particularly preferably 50% by volume or more and 60% by volume or less.

[0120] The silica volume content is the ratio of the silica volume to the sum of the volumes of the epoxy resin, the novolac-type phenolic resin, and the silica. The volume is calculated based on mass and density.

[0121] Furthermore, from the viewpoint of the mechanical and electrical properties of the cured product (described later), preferably, the number-average molecular weight of polyethylene glycol that modifies the lignin and the volume content of silica satisfy a predetermined relationship.

[0122] In the following, the number-average molecular weight of polyethylene glycol is denoted as x. Furthermore, the volume content (volt%) of silica relative to the total amount of epoxy resin, novolac-type phenolic resin, and silica is denoted as y.

[0123] From the viewpoint of the mechanical properties of the cured product (described later), the ratio of the number-average molecular weight x of polyethylene glycol to the volume content y (volume %) of silica (x / y) is, for example, 1.0 or more and 20.0 or less, preferably greater than 3.0 and 18.0 or less, and more preferably 5.0 or more and 15.0 or less.

[0124] In particular, from the viewpoint of electrical properties, the ratio of the number-average molecular weight x of polyethylene glycol to the volume content y (volume %) of silica (x / y) is preferably 6.3 or more and 15.0 or less, more preferably greater than 6.7 and less than 12.0, even more preferably 7.0 or more and 11.0 or less, and most preferably 8.0 or more and 10.0 or less.

[0125] In other words, from the viewpoint of the mechanical and electrical properties of the cured product (described later), the number average molecular weight x of polyethylene glycol and the volume content y (volume %) of silica preferably satisfy the following formula (1), more preferably satisfy the following formula (2), even more preferably satisfy the following formula (3), and particularly preferably satisfy the following formula (4).

[0126] 6.3 ≤ [x / y] ≤ 15.0 (1) 6.7 < [x / y] < 12.0 (2) 7.0 ≤ [x / y] ≤ 11.0 (3) 8.0 ≤ [x / y] ≤ 10.0 (4)

[0127] In other words, for example, if the number-average molecular weight x of polyethylene glycol that modifies the lignin is 200, the volume content y (vol %) of silica is preferably 13 vol % or more and 32 vol % or less, more preferably more than 17 vol % and less than 30 vol %, even more preferably 18 vol % or more and 20 vol % or less, and particularly preferably 20 vol % or more and 25 vol % or less.

[0128] Furthermore, for example, if the number-average molecular weight x of polyethylene glycol that modifies the lignin is 400, the volume content y (vol%) of silica is preferably 27 vol% or more and 64 vol% or less, more preferably more than 33 vol% and less than 60 vol%, even more preferably 36 vol% or more and 57 vol% or less, and particularly preferably 40 vol% or more and 50 vol% or less.

[0129] Furthermore, for example, if the number-average molecular weight x of polyethylene glycol that modifies the lignin is 600, the volume content y (vol%) of silica is preferably 40 vol% or more and 95 vol% or less, more preferably more than 50 vol% and less than 89 vol%, even more preferably 55 vol% or more and 86 vol% or less, and particularly preferably 60 vol% or more and 75 vol% or less.

[0130] If the ratio of the number-average molecular weight x of polyethylene glycol to the volume content y (volume %) of silica (x / y) is within the above range, particularly excellent mechanical and electrical properties (insulating properties) can be obtained. More specifically, when the volume content y (volume %) of silica is relatively large and the number-average molecular weight x of polyethylene glycol is relatively small, the viscosity of the curable resin composition becomes relatively high, which may reduce the dispersibility of silica. In contrast, when the number-average molecular weight x of polyethylene glycol is relatively large, even when the volume content y (volume %) of silica is relatively large, the increase in viscosity of the curable resin composition can be suppressed, and the dispersibility of silica can be improved. As a result, particularly excellent mechanical and electrical properties (insulating properties) can be obtained.

[0131] (5) Manufacturing method The method for producing the curable resin composition is not particularly limited. For example, epoxy resin and novolac-type phenolic resin (and additives as needed) are blended in the above proportions and kneaded by a known kneading method.

[0132] The mixing method is not particularly limited. For example, known mixers can be used. Examples of mixers include single-screw extruders, multi-screw extruders, roll mixers, kneaders, Henschel mixers, and Banbury mixers.

[0133] The mixing conditions are not particularly limited. For example, the mixing temperature is, for example, 80°C to 180°C, preferably 90°C to 170°C, and more preferably 100°C to 160°C. The mixing time is, for example, 3 minutes to 30 minutes, preferably 5 minutes to 20 minutes.

[0134] Then, through the above kneading process, a curable resin composition containing epoxy resin and novolac-type phenolic resin (and additives as needed) is produced.

[0135] (6) Effects The above curable resin composition contains an epoxy resin and a novolac-type phenolic resin, the novolac-type phenolic resin being modified with lignins. Furthermore, the lignins include lignin modified with polyethylene glycol. Therefore, the above curable resin composition can improve the mechanical properties and electrical properties (insulation properties) of the cured product.

[0136] Therefore, the above resin composition is suitably used in the manufacture of cured products.

[0137] 2.Cured product The cured product is obtained by thermally curing the above-mentioned curable resin composition using a known method. That is, by thermally curing the above-mentioned curable resin composition using a known molding method and molding it into any shape, a cured product having any shape can be obtained. More specifically, examples of molding methods include transfer molding and compression molding, with transfer molding being preferred.

[0138] The molding conditions are not particularly limited and are set as appropriate according to the purpose and application. More specifically, the molding temperature is, for example, 120°C to 250°C, preferably 150°C to 200°C. The molding time is, for example, 1 minute to 30 minutes, preferably 5 minutes to 15 minutes.

[0139] This process produces a cured product. The cured product is then aged (cured) as needed.

[0140] The aging conditions are not particularly limited and are set as appropriate according to the purpose and application. More specifically, the aging temperature is, for example, 120°C to 250°C, preferably 150°C to 200°C. The aging time is, for example, 30 minutes to 300 minutes, preferably 60 minutes to 180 minutes.

[0141] As a result, the epoxy resin and the novolac-type phenolic resin undergo a thermosetting reaction, yielding a cured resin.

[0142] The density of the cured resin is, for example, 1.0 g / cm³. 3 More than 1.5g / cm 3 Preferably, 1.0 g / cm³ 3 More than 1.3g / cm 3 More preferably, 1.1 g / cm³ 3 More than 1.2g / cm 3 The following applies:

[0143] Furthermore, if the curable resin composition contains additives, the cured product will contain, for example, the cured resin and the additives.

[0144] The proportion of cured resin in the cured product is, for example, the same as the total amount of epoxy resin and novolac-type phenolic resin in the above-mentioned curable resin composition.

[0145] Furthermore, the proportion of additives (e.g., curing accelerators, internal release agents, and fillers) in the cured product is the same as, for example, the proportion of additives (e.g., curing accelerators, internal release agents, and fillers) in the above-mentioned curable resin composition.

[0146] More specifically, the cured product preferably contains a cured resin and silica. The volume content of silica relative to the total amount of cured resin and silica is, for example, 10% to 99% by volume, preferably 30% to 90% by volume, more preferably 50% to 80% by volume, even more preferably 50% to 70% by volume, and particularly preferably 50% to 60% by volume.

[0147] Since such cured products are cured products of the above-mentioned curable resin composition, they possess excellent mechanical properties and electrical properties (insulating properties).

[0148] 3.Applications The above-described curable resin composition and its cured product are widely used in various industrial fields where mechanical properties and electrical properties (insulating properties) are required. Examples of such industrial fields include the electrical components field and the electronic components field. Particularly preferably, the curable resin composition and its cured product are suitably used as semiconductor encapsulants. [Examples]

[0149] Next, the present invention will be described based on examples, but the present invention is not limited to the following examples. Unless otherwise specified, "parts" and "%" are based on mass. Furthermore, specific numerical values ​​such as blending ratios (content), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to" or "greater than") of the blending ratios (content), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0150] 1. Epoxy resin Preparation Example A1 (Commercially available epoxy resin) As the epoxy resin, we prepared a commercially available o-cresol novolac type epoxy resin (product name EPICLON N-665, epoxy equivalent 211 g / eq, manufactured by DIC (hereinafter sometimes referred to as OCNE)).

[0151] The density of o-cresol novolac type epoxy resin is 1.1 g / cm³. 3 The density was measured using an electronic balance (commercially available, manufactured by Mettler-Toledo) and a density measurement kit for Mettler-Toledo balances (commercially available, manufactured by Mettler-Toledo), according to standard procedures (the same applies hereafter).

[0152] 2. PEG-modified lignin Preparation Example B1 (PEG200 denatured lignin) Lignin modified with polyethylene glycol having a number-average molecular weight of 200 (hereinafter referred to as PEG200 modified lignin) was produced using the following method.

[0153] Specifically, 230 parts by mass of commercially available polyethylene glycol with a number-average molecular weight of 200 (hereinafter referred to as PEG200) and 0.69 parts by mass of sulfuric acid as an acid catalyst (0.3 parts by mass per 100 parts by mass of PEG200) were placed in a reaction vessel and stirred. Next, 46 parts by mass of oven-dried cedar wood powder were added to the reaction vessel, and the temperature was raised to 140°C under atmospheric pressure and the reaction was carried out for 90 minutes while stirring. Then, the reaction vessel was cooled, and after confirming that the temperature had fallen below 40°C, 280 parts by mass of sodium hydroxide (0.2 mol / L) were added and stirred for 30 minutes. Next, the obtained solid component (pulp) was removed by filter press and the solution component was recovered. Then, sulfuric acid was added to the obtained solution component and the pH was adjusted to 2.0. This obtained a suspension of PEG200-modified lignin. Subsequently, the PEG200-modified lignin was recovered by centrifugation.

[0154] Preparation Example B2 (PEG400 denatured lignin) Polyethylene glycol with a number-average molecular weight of 200 was used instead of polyethylene glycol with a number-average molecular weight of 400 (hereinafter referred to as PEG400). Except for this, the same method as in Preparation Example B1 was used to obtain lignin modified with polyethylene glycol with a number-average molecular weight of 400 (hereinafter referred to as PEG400-modified lignin).

[0155] Preparation example B3 (PEG600 denatured lignin) Polyethylene glycol with a number-average molecular weight of 200 was used instead of polyethylene glycol with a number-average molecular weight of 600 (hereinafter referred to as PEG600). Except for this, lignin modified with polyethylene glycol with a number-average molecular weight of 600 (hereinafter referred to as PEG600-modified lignin) was obtained using the same method as in Preparation Example B1.

[0156] 3. Novolac-type phenolic resin Preparation Example C1 (PEG200 modified lignin-novolac type phenolic resin) 493.5 parts by mass of phenol were placed in a flask and heated to approximately 50°C to liquefy the phenol. Then, 300 parts by mass of PEG200 modified lignin (Preparation Example B1) were added to the flask.

[0157] Next, 7.62 parts by mass of oxalic acid (acid catalyst) and 117.3 parts by mass of paraformaldehyde were added to the flask, and the contents of the flask were reacted at 95°C for 2.5 hours. Then, the contents of the flask were heated to 110°C at a rate of 0.5°C / min and reacted at 110°C for 1.5 hours. Then, the contents of the flask were heated to 120°C at a rate of 0.5°C / min and reacted at 120°C for 2 hours.

[0158] Next, 2300 parts by mass of water were added to the flask, and the contents of the flask were vigorously stirred to remove the water by decantation, thereby removing oxalic acid and phenol.

[0159] Furthermore, residual phenol was removed by vacuum distillation at 120°C and 0.08 MPa while adding water to the contents of the flask as needed. This vacuum distillation was repeated until the residual phenol content was 1% or less.

[0160] Based on the above, a novolac-type phenolic resin modified with PEG200-modified lignin (hereinafter referred to as PEG200-lignin-novolac-type phenolic resin) was obtained.

[0161] Furthermore, the reaction ratio (mass ratio) between PEG200-modified lignin and phenol was calculated by subtracting the amount of residual phenol from the amount of phenol added. As a result, the amount of PEG200-modified lignin (L) per 100 parts by mass of phenol (Ph) was 40 parts by mass (Ph:L = 100:40).

[0162] The density of PEG200 lignin-novolac type phenolic resin is 1.1 g / cm³. 3 The density was measured using an electronic balance (commercially available, manufactured by Mettler-Toledo) and a density measurement kit for Mettler-Toledo balances (commercially available, manufactured by Mettler-Toledo) (the same applies hereafter).

[0163] Furthermore, the phenolic hydroxyl group equivalent of PEG200 lignin-novolac type phenolic resin was 165 g / eq. The phenolic hydroxyl group equivalent was calculated using the following method (the same method applies hereafter).

[0164] Specifically, first, the percentage of structural components derived from PEG-modified lignin (PEG200-modified lignin in preparation example C1 (hereinafter the same)) contained in the PEG-lignin-novolac type phenolic resin was calculated using the following formula.

[0165] The percentage of structural components derived from PEG-modified lignin = (Amount of PEG-modified lignin used / Amount of PEG-lignin-novolac type phenolic resin produced) × 100

[0166] More specifically, in preparation example C1, the content of structural components derived from PEG-modified lignin was 40% by mass relative to the total amount of PEG200 lignin-novolac type phenolic resin.

[0167] Furthermore, the percentage of structural components derived from novolac-type phenolic resin in PEG200 lignin-novolac-type phenolic resin was calculated using the following formula.

[0168] The percentage of structural components derived from novolac-type phenolic resin = {1 - (amount of novolac-type phenolic resin used / amount of PEG-lignin-novolac-type phenolic resin produced)} × 100

[0169] More specifically, in preparation example C1, the content of structural components derived from novolac-type phenolic resin was 60% by mass relative to the total amount of PEG200 lignin-novolac-type phenolic resin.

[0170] Furthermore, it was assumed that lignin is a polymer of monolignol (lignin monomer), and that lignin consists of a basic lignin skeleton (i.e., guaiacyllignin (G type), syringyllignin (S type), and / or p-hydroxyphenyllignin (H type)). It was also assumed that the average molecular weight of the basic lignin skeleton is 200. The proportion of phenolic hydroxyl groups contained in the structural parts derived from PEG-modified lignin was calculated using the following method.

[0171] In other words, in PEG-modified lignin, the ratio of the mass of the PEG-derived structural portion to the mass of the lignin-derived structural portion (PEG-derived structural portion / lignin-derived structural portion (mass ratio)) was assumed to be 0.25 (ACS Sustainable Chem. Eng. 2018, 6, 7841-7848). That is, in PEG-modified lignin, the number of PEG (average molecular weight 200) added to four lignin basic skeletons (average molecular weight 200) was assumed to be one. To put it another way, it was assumed that PEG-modified lignin contained three lignin basic skeletons without PEG for every one lignin basic skeleton with PEG attached.

[0172] Then, the average value based on mass of the average molecular weight of the lignin base skeleton with PEG attached and the average molecular weight of the lignin base skeleton without PEG attached (hereinafter referred to as the average molecular weight of the PEG-modified lignin base skeleton) was calculated according to the following formula.

[0173] Average molecular weight of PEG-modified lignin base skeleton = [(Average molecular weight of lignin base skeleton without PEG attachment × Total number of lignin base skeletons + Average molecular weight of PEG) / Total number of lignin base skeletons]

[0174] In the above formula, the total number of lignin basic skeletons is the sum of the number of lignin basic skeletons without PEG attached and the number of lignin basic skeletons with PEG attached.

[0175] More specifically, in preparation example C1, the average molecular weight of the PEG-modified lignin basic skeleton was 250 (= ((200 × 4 + 200) / 4) = 250 g / mol).

[0176] Furthermore, the amount of phenolic hydroxyl groups per 100 moles of lignin basic skeleton was assumed to be 25 moles (ACS Sustainable Chem. Eng. 2016, 4, 2861-2868). In other words, the molar ratio of phenolic hydroxyl groups to the lignin basic skeleton was assumed to be 25 mol%. The equivalent amount of phenolic hydroxyl groups was then calculated using the following method.

[0177] The proportion of phenolic hydroxyl groups in the structural portion derived from PEG-modified lignin = molar ratio of phenolic hydroxyl groups relative to the lignin base skeleton × (molecular weight of hydroxyl group = 17 / average molecular weight of PEG-modified lignin base skeleton) × 100

[0178] More specifically, in preparation example C1, the proportion of phenolic hydroxyl groups in the structural portion derived from PEG-modified lignin was 1.7% by mass (= 0.25 × (17 / 250) × 100) relative to the total amount of the structural portion derived from PEG-modified lignin.

[0179] Furthermore, the percentage of phenolic hydroxyl groups in the structural portion derived from novolac-type phenolic resin was calculated using the following formula.

[0180] The content of phenolic hydroxyl groups in the structural portion derived from novolac-type phenolic resin = [17 (molecular weight of hydroxyl group) × 1 (number of hydroxyl groups per repeating unit of novolac-type phenolic resin) / 106 g / eq (equivalent amount of hydroxyl groups in novolac-type phenolic resin)] × 100

[0181] More specifically, in preparation example C1, the content of phenolic hydroxyl groups in the structural portion derived from the novolac-type phenolic resin was 16.0% by mass (= 17 × (1 / 10⁶) × 100) relative to the total amount of the structural portion derived from the novolac-type phenolic resin.

[0182] The percentage of phenolic hydroxyl groups in the PEG-lignin-novolac type phenolic resin was then calculated using the following formula.

[0183] The content of phenolic hydroxyl groups in PEG-lignin-novolac type phenolic resin = [Content of structural parts derived from PEG-modified lignin in PEG-lignin-novolac type phenolic resin (mass%)] × [Content of phenolic hydroxyl groups in structural parts derived from PEG-modified lignin (mass%) / 100] + [Content of structural parts derived from novolac type phenolic resin in PEG-lignin-novolac type phenolic resin (mass%)] × [Content of phenolic hydroxyl groups in structural parts derived from novolac type phenolic resin (mass%) / 100]

[0184] More specifically, in preparation example C1, the content of phenolic hydroxyl groups in the PEG-lignin-novolac type phenolic resin was 10.2% by mass (= 1.7% by mass × (40% by mass / 100) + 16.0% by mass × (60% by mass / 100)).

[0185] In other words, the mass of phenolic hydroxyl groups contained in 100g of PEG200 lignin-novolac type phenolic resin was 10.28g, or in other words, 0.6 moles (=10.2g / molecular weight 17). Therefore, the equivalent amount of phenolic hydroxyl groups in PEG200 lignin-novolac type phenolic resin was 165g / eq.

[0186] Preparation Example C2 (PEG400 lignin-modified novolac-type phenolic resin) PEG400-modified lignin (Preparation Example B2) was used instead of 300 parts by mass of PEG200-modified lignin (Preparation Example B1). Otherwise, the same method as in Preparation Example C1 was used to obtain a novolac-type phenolic resin modified with PEG400-modified lignin (PEG400 lignin-novolac-type phenolic resin).

[0187] The amount of PEG400-modified lignin (L) per 100 parts by mass of phenol (Ph) was 40 parts by mass (Ph:L = 100:40).

[0188] The density of PEG400 lignin-novolac type phenolic resin is 1.1 g / cm³. 3 That was the case.

[0189] Furthermore, the phenolic hydroxyl group equivalent of the PEG400 lignin-novolac type phenolic resin was 165 g / eq.

[0190] Preparation Example C3 (PEG600 Lignin-Modified Novolac-Type Phenolic Resin) PEG600-modified lignin (Preparation Example B3) was used instead of 300 parts by mass of PEG200-modified lignin (Preparation Example B1). Otherwise, the same method as in Preparation Example C1 was used to obtain a novolac-type phenolic resin modified with PEG600-modified lignin (PEG600 lignin-novolac-type phenolic resin).

[0191] The amount of PEG600-modified lignin (L) per 100 parts by mass of phenol (Ph) was 40 parts by mass (Ph:L = 100:40).

[0192] The density of PEG600 lignin-novolac type phenolic resin is 1.1 g / cm³. 3 That was the case.

[0193] Furthermore, the phenolic hydroxyl group equivalent of PEG600 lignin-novolac type phenolic resin was 165 g / eq.

[0194] Preparation Example C4 (Commercially available novolac-type phenolic resin) A commercially available novolac-type phenolic resin (lignin-free novolac-type phenolic resin, trade name CP506F, phenolic hydroxyl group equivalent 106 g / eq, manufactured by Asahi Organic Chemicals Co., Ltd. (hereinafter sometimes referred to as PN)) was prepared.

[0195] The density of novolac-type phenolic resin is 1.1 g / cm³. 3 That was the case.

[0196] 4. Additives Preparation example D1 (filler) As a filler, commercially available fused silica (product name RD-8, particle size 15 μm, density 2.3 g / cm³) is used. 3 (Made by Ryusen)

[0197] Preparation Example D2 (Curing Accelerator) As a curing accelerator, 2-ethyl-4-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) was prepared.

[0198] Preparation Example D3 (Internal Release Agent) Rice wax (product name NC-1720, manufactured by Cerarica NODA) was prepared as an internal mold release agent.

[0199] 5. Curable resin composition and cured product Examples 1-7 and Comparative Examples 1-3 [Curable resin composition] According to the formulations shown in Tables 1 to 3, epoxy resin, novolac-type phenolic resin, silica (filler), 2-ethyl-4-methylimidazole (curing accelerator), and rice wax (internal release agent) were melt-kneaded for 5 minutes at 100-110°C using a hot roll to obtain a curable resin composition.

[0200] In the curable resin composition, the equivalent ratio of epoxy groups of the epoxy resin to phenolic hydroxyl groups of the novolac-type phenolic resin (epoxy groups / phenolic hydroxyl groups) was 1.0.

[0201] Furthermore, in Comparative Example 1 and Examples 1-3, the blending ratio of each component was adjusted so that the volume content of silica relative to the total amount of epoxy resin, novolac-type phenolic resin, and silica was 50% by volume.

[0202] Furthermore, in Comparative Example 2 and Examples 4-6, the blending ratio of each component was adjusted so that the volume content of silica relative to the total amount of epoxy resin, novolac-type phenolic resin, and silica was 60% by volume.

[0203] Furthermore, in Comparative Example 3 and Example 7, the blending ratio of each component was adjusted so that the volume content of silica relative to the total amount of epoxy resin, novolac-type phenolic resin, and silica was 70% by volume.

[0204] [Cured product] Using a transfer molding apparatus, the above curable resin composition was molded at 170°C for 10 minutes and heat-cured to obtain a cured product. The cured product was then aged at 180°C for 2 hours.

[0205] The shape of the cured material was modified according to the respective test methods described below. More specifically, rectangular test specimens used for bending tests, notched test specimens used for Charpy impact tests, and disc-shaped test specimens (75 mmφ) used for other tests were each manufactured as cured products of the above-mentioned curable resin composition.

[0206] 6. Evaluation The cured products of each example and comparative example were evaluated using the following method. The results are shown in Tables 1 to 3.

[0207] (1) Glass transition temperature (heat resistance, Tg) The dynamic viscoelasticity of the solid was measured using Rheogel-E4000 (manufactured by UBM Corporation) (frequency 1 Hz, heating rate 2 °C / min). The peak temperature of the resulting tanδ curve was then determined as the glass transition temperature (Tg).

[0208] (2) Bending strength In accordance with JIS K6911 (1995), a three-point bending test was performed at a crosshead speed of 3 mm / min and a span of 100 mm, and the bending strength and bending modulus were measured.

[0209] (3) Maximum point elongation In accordance with JIS K6911 (1995), a three-point bending test was performed at a crosshead speed of 3 mm / min and a span of 100 mm, and the maximum point elongation was measured.

[0210] The maximum point elongation is the strain (maximum point elongation) when the material is bent until it breaks, and was calculated using the following formula.

[0211] Maximum point elongation (ε)=[6T / L2]× ΔL (T: sample thickness, L: distance between supports, ΔL: bending deflection)

[0212] (4) Charpy impact strength In accordance with JIS K6911 (1995), the Charpy impact strength was measured using an impact testing machine (manufactured by Toyo Seiki Seisakusho).

[0213] (5) Volume resistivity (electrical insulation) In accordance with JIS K6911 (1995 edition), the volume resistivity (Ω·cm) was measured using an HP4339A (manufactured by Agilent Technologies).

[0214] [Table 1]

[0215] [Table 2]

[0216] [Table 3]

[0217] Details of the abbreviations in the table are as follows. PEG200 Modified Lignin-Novolac Type Phenolic Resin: Preparation Example C1: Lignin-modified novolac type phenolic resin, polyethylene glycol (PEG) with molecular weight 200 for lignin modification.

[0218] PEG400 Modified Lignin-Novolac Phenolic Resin: Preparation Example C2: Lignin-modified novolac phenolic resin, polyethylene glycol (PEG) with molecular weight 400 to modify lignin.

[0219] PEG600 Modified Lignin-Novolac Phenolic Resin: Preparation Example C3: Lignin-modified novolac phenolic resin, polyethylene glycol (PEG) with molecular weight 600 to modify lignin.

[0220] Novolac-type phenolic resin: Preparation example C4, lignin-unmodified novolac-type phenolic resin, trade name CP506F, phenolic hydroxyl group equivalent 106 g / eq, manufactured by Asahi Organic Chemicals Co., Ltd.

Claims

1. This is a curable resin composition containing epoxy resin and novolac-type phenolic resin. The aforementioned novolac-type phenolic resin contains a novolac-type phenolic resin modified with lignins, The lignins are a curable resin composition containing lignin modified with polyethylene glycol.

2. The curable resin composition according to claim 1, wherein the number average molecular weight of the polyethylene glycol is 200 or more and 600 or less.

3. Furthermore, the curable resin composition according to claim 1, further containing silica.

4. The number average molecular weight x of the polyethylene glycol, The epoxy resin, the novolac-type phenolic resin, and the volume content y (volume %) of the silica relative to the total amount of silica, The curable resin composition according to claim 3, wherein the following formula is satisfied. 7.0≦[x / y]≦11.0

5. A cured product of a curable resin composition according to any one of claims 1 to 4.

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