Curable resin composition, cured product, coating composition, and resol-type phenolic resin

Abstract

To provide a curable resin composition and a coating composition capable of obtaining a cured product having excellent heat resistance, a cured product and a coating film having excellent heat resistance and a resol-type phenolic resin capable of obtaining a cured product having excellent adhesion properties.SOLUTION: There is provided a curable resin composition comprising a lignin-based resin having a hydroxyl group and a reactive silane coupling agent having a reactive functional group which can react with a hydroxyl group. The lignin-based resin contains at least one selected from the group consisting of a lignin modified by a polyethylene glycol, a novolac product of a lignin modified by a polyethylene glycol and a resol product of a lignin modified by a polyethylene glycol. The resol-type phenolic resin contains a reaction product obtained by reacting a lignin modified by a polyethylene glycol, phenols and aldehydes under an alkali catalyst.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a curable resin composition, a cured product, a coating composition, and a coating film. [Background technology]

[0002] The curable resin composition is, for example, a composition containing a thermosetting resin. The curable resin composition is cured by heating to form a cured product. The curable resin composition is widely used in various industrial fields. Examples of applications of the curable resin composition include molding materials, adhesives, and coating materials.

[0003] As a curable resin composition, a phenolic resin derived from lignin has been proposed from the viewpoint of environmental friendliness. More specifically, as a curable resin composition, for example, a molding material containing a lignophenol derivative and a silane coupling agent has been proposed. In addition, as a cured product, for example, a transparent heat-resistant material obtained by reacting a lignophenol derivative with a silane coupling agent has been proposed (for example, see Patent Document 1).

[0004] Also, resol-type phenolic resins are known as curable resin compositions. The resol-type phenolic resins are produced, for example, by reacting phenol with an aldehyde in the presence of an alkali catalyst. More specifically, resol-type phenolic resins are known that are obtained by reacting phenol with formalin in the presence of sodium hydroxide (see, for example, Patent Document 2 (Production Example 4)). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-342270 A [Patent Document 2] JP 2015-48395 A Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, the curable resin composition and the cured product thereof are required to have better heat resistance.

[0007] The present invention includes a curable resin composition and a coating composition which can give a cured product having excellent heat resistance, and a cured product and a coating film having excellent heat resistance.

[0008] Furthermore, resol-type phenolic resins and their cured products are required to have better adhesion.

[0009] The present invention includes a resol-type phenolic resin capable of giving a cured product having excellent adhesion. [Means for solving the problem]

[0010] The present invention [1] includes a curable resin composition comprising a lignin-based resin having a hydroxyl group and a reactive silane coupling agent having a reactive functional group capable of reacting with the hydroxyl group, wherein the lignin-based resin comprises at least one selected from the group consisting of lignin modified with polyethylene glycol, a novolak product of lignin modified with polyethylene glycol, and a resol product of lignin modified with polyethylene glycol.

[0011] The present invention [2] includes the curable resin composition according to the above [1], in which the novolak or resol compound contains a reaction product of lignin modified with polyethylene glycol, a phenol, and an aldehyde.

[0012] The present invention [3] includes the curable resin composition according to the above [1] or [2], in which the polyethylene glycol has a number average molecular weight of 400 or more.

[0013] The present invention [4] includes the curable resin composition according to any one of the above [1] to [3], in which the reactive functional group contains an epoxy group.

[0014] The present invention [5] includes the curable resin composition according to any one of the above [1] to [4], further comprising a reaction catalyst for the reaction between the hydroxyl group and the reactive functional group.

[0015] The present invention [6] includes the curable resin composition according to the above [5], in which the reaction catalyst contains an imidazole-type catalyst.

[0016] The present invention [7] includes a cured product of the curable resin composition according to any one of the above [1] to [6].

[0017] The present invention [8] includes the cured product described in [7] above, which contains a reaction product obtained by reacting the hydroxyl group of the lignin-based resin with the reactive functional group of the reactive silane coupling agent, and the reaction product contains a polysiloxane structure obtained by condensation of the alkoxysilyl group of the reactive silane coupling agent.

[0018] The present invention [9] includes a coating composition containing the curable resin composition according to any one of the above [1] to [6].

[0019] The present invention

[10] includes a coating film comprising the cured product described in [7] or [8] above.

[0020] The present invention

[11] includes a resol-type phenolic resin that contains a reaction product obtained by reacting lignin modified with polyethylene glycol, a phenol, and an aldehyde in the presence of an alkali catalyst. Effect of the Invention

[0021] In the curable resin composition of the present invention and the coating composition of the present invention, the lignin-based resin contains at least one selected from the group consisting of lignin modified with polyethylene glycol, a novolak product of lignin modified with polyethylene glycol, and a resol product of lignin modified with polyethylene glycol. Therefore, the curable resin composition can produce a cured product having excellent heat resistance.

[0022] Furthermore, the cured product of the present invention and the coating film of the present invention have excellent heat resistance since they are obtained by curing the above-mentioned curable resin composition.

[0023] In addition, the resol type phenolic resin of the present invention contains lignin modified with polyethylene glycol as a reaction raw material, and therefore, the resol type phenolic resin can produce a cured product having excellent adhesion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 1. Curable resin composition The curable resin composition is an uncured resin for forming a cured product (resin cured product) described later. The curable resin composition contains, as essential components, a lignin-based resin having a hydroxyl group and a reactive silane coupling agent having a reactive functional group capable of reacting with the hydroxyl group.

[0025] (1) Lignin-based resin The lignin-based resin contains at least one selected from the group consisting of lignin modified with polyethylene glycol (hereinafter, sometimes referred to as PEG-modified lignin), a novolac product of lignin modified with polyethylene glycol (hereinafter, sometimes referred to as PEG-modified lignin-novolac resin), and a resol product of lignin modified with polyethylene glycol (hereinafter, sometimes referred to as PEG-modified lignin-resol resin). Preferably, the lignin-based resin is at least one selected from the group consisting of PEG-modified lignin, PEG-modified lignin-novolac resin, and PEG-modified lignin-resol resin.

[0026] [PEG-modified lignin] In PEG-modified lignin, polyethylene glycol (PEG) modifies lignin and improves the heat resistance of the cured product (described later).

[0027] The number average molecular weight of polyethylene glycol is, for example, 100 or more, preferably 200 or more, more preferably 300 or more, and even more preferably 400 or more. The number average molecular weight of polyethylene glycol is, for example, 1000 or less, preferably 900 or less, more preferably 800 or less, and even more preferably 600 or less. If the number average molecular weight is within the above range, a cured product (described later) having excellent heat resistance can be obtained. The number average molecular weight can be determined as a polyethylene glycol-equivalent molecular weight by a known gel permeation chromatography method.

[0028] In the PEG-modified lignin, lignin is a natural product and a polymeric phenolic compound. Lignin includes, for example, guaiacyl lignin (G type), syringyl lignin (S type), and / or p-hydroxyphenyl lignin (H type) as a basic skeleton. Lignin is, for example, naturally occurring lignin and is contained in plants in general.

[0029] PEG-modified lignin is produced, for example, in accordance with the method described in JP 2017-197517 A. In this method, for example, a plant material (lignocellulose) serving as a raw material for lignin is digested with polyethylene glycol.

[0030] The digestion method is not particularly limited, but for example, a plant material that is the raw material for lignin, polyethylene glycol, and an inorganic acid (for example, hydrochloric acid, sulfuric acid, etc.) as an acid catalyst are mixed and reacted.

[0031] The blending ratio of polyethylene glycol is, for example, 200 parts by mass or more, preferably 300 parts by mass or more, relative to 100 parts by mass of the plant material that is the raw material for lignin. The blending ratio of polyethylene glycol is, for example, 1000 parts by mass or less, preferably 600 parts by mass or less, relative to 100 parts by mass of the plant material that is the raw material for lignin.

[0032] The mixing ratio of the inorganic acid (100% conversion) is, for example, 0.1 parts by mass or more, preferably 0.2 parts by mass or more, relative to 100 parts by mass of polyethylene glycol. The mixing ratio of the inorganic acid (100% conversion) is, for example, 2 parts by mass or less, preferably 1 part by mass or less, relative to 100 parts by mass of polyethylene glycol.

[0033] The reaction conditions include normal pressure. The reaction temperature is, for example, 120° C. or higher, preferably 130° C. or higher. The reaction temperature is, for example, 180° C. or lower, preferably 150° C. or lower. The reaction time is, for example, 60 minutes or longer. The reaction time is, for example, 240 minutes or shorter, preferably 120 minutes or shorter.

[0034] After the reaction is completed, an alkali is added to the reaction solution in an appropriate ratio to adjust the pH. Examples of the alkali include ammonia and sodium hydroxide. This allows the PEG-modified lignin to be extracted into the solution. The pH after the adjustment is, for example, 8 or more, preferably 10 or more, more preferably 10.5 or more, and, for example, 14 or less.

[0035] By the above method, pulp is obtained as a solid component and PEG-modified lignin is obtained as a solution component.

[0036] Next, in this method, the solid component (pulp) is separated from the reaction product by a known separation method such as filtration, pressing, or centrifugation, and the solution component is recovered. In addition, in this method, if necessary, the solid component (pulp) can be washed and the solution (PEG-modified lignin) impregnated in the solid component can be recovered. Thereafter, in this method, an inorganic acid (e.g., hydrochloric acid, sulfuric acid, etc.) is added to adjust the pH to precipitate and deposit the PEG-modified lignin. The pH after the adjustment is, for example, 1.5 or more, for example, 5 or less, preferably 3 or less, and more preferably 2 or less.

[0037] This allows the PEG-modified lignin to precipitate, and the resulting precipitate can be collected by a known method such as filtration, pressing, or centrifugation to obtain the PEG-modified lignin as a solid content.

[0038] [PEG-modified lignin-novolac resin] The PEG-modified lignin-novolac resin (the novolac product of PEG-modified lignin) is a novolac-type phenolic resin modified by PEG-modified lignin. More specifically, the PEG-modified lignin-novolac resin (the novolac product of PEG-modified lignin) contains a reaction product of the above-mentioned PEG-modified lignin, phenols, and aldehydes. Preferably, the PEG-modified lignin-novolac resin (the novolac product of PEG-modified lignin) is composed of a reaction product of the above-mentioned PEG-modified lignin, phenols, and aldehydes.

[0039] The phenols are phenol and phenol derivatives (phenol modified products). Examples of the phenols include phenol, bifunctional phenol derivatives, trifunctional phenol derivatives, and tetrafunctional phenol derivatives. Examples of the bifunctional phenol derivatives include o-cresol, p-cresol, p-ter-butylphenol, p-phenylphenol, p-cumylphenol, and p-nonylphenol. Examples of the trifunctional phenol derivatives include m-cresol, resorcinol, and 3,5-xylenol. Examples of the tetrafunctional phenol derivatives include bisphenol A and dihydroxydiphenylmethane. Examples of the phenol derivatives include halogenated phenols. Halogenated phenols are halides of phenol or phenol derivatives. Examples of halogens include chlorine and bromine. These phenols can be used alone or in combination of two or more kinds. In the phenol derivatives, the timing at which phenol is derivatized (modified) is not particularly limited. For example, the derivatization of phenol may be carried out before, after, or simultaneously with the reaction of a phenol with an aldehyde. As the phenol, phenol is preferably used.

[0040] Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, n-butylaldehyde, isobutylaldehyde, furfural, glyoxal, benzaldehyde, trioxane, and tetraoxane.Also, a part of the aldehyde may be substituted with furfuryl alcohol or the like.These aldehydes can be used alone or in combination of two or more kinds.Preferably, the aldehydes include formaldehyde and paraformaldehyde.

[0041] The aldehydes can be used, for example, as an aqueous solution. In such a case, the concentration of the aldehydes is, for example, 10% by mass or more, preferably 20% by mass or more, and for example, 99% by mass or less, preferably 95% by mass or less.

[0042] Ketones can also 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, for example, 0.01 parts by mass or more, preferably 1 part by mass or more, based on the solid content, relative to 100 parts by mass of aldehydes. The amount of ketones is, for example, 200 parts by mass or less, preferably 100 parts by mass or less, based on the solid content, relative to 100 parts by mass of aldehydes.

[0043] To react the PEG-modified lignin, phenols, and aldehydes (and optionally ketones (hereinafter the same)), the above components (PEG-modified lignin, phenols, and aldehydes) are mixed and heated in the presence of an acid catalyst (described below).

[0044] In this reaction, the mixing ratio of the phenols is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, and more preferably 100 parts by mass or more, relative to 100 parts by mass of the PEG-modified lignin. The mixing ratio of the phenols is, for example, 1000 parts by mass or less, preferably 500 parts by mass or less, more preferably 350 parts by mass or less, and even more preferably 200 parts by mass or less, relative to 100 parts by mass of the PEG-modified lignin.

[0045] In other words, the blending ratio of the PEG-modified lignin is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 50 parts by mass or more, and particularly preferably 70 parts by mass or more, relative to 100 parts by mass of the phenols. The blending ratio of the PEG-modified lignin is, for example, 300 parts by mass or less, preferably 200 parts by mass or less, and more preferably 100 parts by mass or less, relative to 100 parts by mass of the phenols.

[0046] The mixing ratio of the aldehydes is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, relative to 100 parts by mass of the phenols.The mixing ratio of the aldehydes is, for example, 35 parts by mass or less, preferably 30 parts by mass or less, relative to 100 parts by mass of the phenols.

[0047] The mixing ratio of the aldehydes is, for example, 1.5 parts by mass or more, preferably 3 parts by mass or more, relative to 100 parts by mass of the PEG-modified lignin. The mixing ratio of the aldehydes is, for example, 350 parts by mass or less, preferably 300 parts by mass or less, relative to 100 parts by mass of the PEG-modified lignin.

[0048] In this reaction, an acid catalyst is added, that is, the above components react in the presence of an acid catalyst.

[0049] Examples of the acid catalyst include Lewis acids. Examples of the Lewis acids include organic acids, inorganic acids, and metal salts. Examples of the organic acids include carboxylic acid compounds, sulfonic acid compounds, and phosphoric acid compounds. Examples of the carboxylic acid compounds include formic acid, acetic acid, and oxalic acid. Examples of the sulfonic acid compounds include methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, cumenesulfonic acid, dinonylnaphthalene monosulfonic acid, and dinonylnaphthalene disulfonic acid. Examples of the phosphoric acid compounds include phosphoric acid esters. More specifically, examples of the phosphoric acid esters include phosphoric acid esters having an alkyl group having 1 to 18 carbon atoms. Examples of the phosphoric acid compounds include trimethyl phosphate, triethyl phosphate, monobutyl phosphate, dibutyl phosphate, tributyl phosphate, and trioctyl phosphate. Examples of the 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 octylate, zinc benzoate, zinc oxide, and lead oxide. When a metal salt is used as an acid catalyst (Lewis acid), a high ortho novolac structure is formed as a phenol novolac structure, and thus the curing speed is improved. These acid catalysts can be used alone or in combination of two or more kinds. As the acid catalyst, preferably, an organic acid is used, more preferably, a carboxylic acid compound is used, and even more preferably, oxalic acid is used.

[0050] The mixing ratio of the acid catalyst relative to 100 parts by mass of the phenols is, for example, 0.1 parts by mass or more, preferably 0.3 parts by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass or less.

[0051] The timing of adding the acid catalyst is not particularly limited. For example, the acid catalyst may be added in advance to at least one of the PEG-modified lignin, the phenols, and the aldehydes. The acid catalyst may be added simultaneously when the PEG-modified lignin, the phenols, and the aldehydes are mixed. Furthermore, the acid catalyst may be added after the PEG-modified lignin, the phenols, and the aldehydes are mixed.

[0052] The reaction conditions include atmospheric pressure. The reaction temperature is, for example, 50° C. or higher, preferably 80° C. or higher. The reaction temperature is, for example, 200° C. or lower, preferably 180° C. or lower. The reaction time is, for example, 1 hour or longer, preferably 2 hours or longer. The reaction time is, for example, 20 hours or shorter, preferably 15 hours or shorter.

[0053] This causes the PEG-modified lignin to react with the phenols and aldehydes under the acid catalyst, resulting in a reaction product, a novolac of the PEG-modified lignin (PEG-modified lignin-novolac resin).

[0054] In the reaction of the PEG-modified lignin, the phenols, and the aldehydes, the above components can be mixed together and reacted together as described above, but the above components can also be mixed sequentially and reacted sequentially.

[0055] More specifically, in the sequential reaction, the PEG-modified lignin is first reacted with a phenol to prepare a PEG-modified lignin-phenol composition as a reaction product of the PEG-modified lignin and the phenol.

[0056] In the reaction between the PEG-modified lignin and the phenols, the phenols are blended in an excess equivalent amount relative to the PEG-modified lignin. Specifically, the blending ratio of the phenols is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, more preferably 100 parts by mass or more, relative to 100 parts by mass of the PEG-modified lignin. The blending ratio of the phenols is, for example, 1000 parts by mass or less, preferably 500 parts by mass or less, more preferably 350 parts by mass or less, relative to 100 parts by mass of the PEG-modified lignin. In other words, the blending ratio of the PEG-modified lignin is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 30 parts by mass or more, relative to 100 parts by mass of the phenols. The blending ratio of the PEG-modified lignin is, for example, 300 parts by mass or less, preferably 200 parts by mass or less, more preferably 100 parts by mass or less, relative to 100 parts by mass of the phenols.

[0057] In this reaction, the above-mentioned acid catalyst is added. The mixing ratio of the acid catalyst is, for example, 0.1 parts by mass or more, preferably 0.3 parts by mass or more, relative to 100 parts by mass of the phenols. The mixing ratio of the acid catalyst is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, relative to 100 parts by mass of the phenols.

[0058] The timing of adding the acid catalyst is not particularly limited. For example, the acid catalyst may be added in advance to at least one of the PEG-modified lignin and the phenols. The acid catalyst may be added simultaneously when the PEG-modified lignin and the phenols are mixed. The acid catalyst may be added after the PEG-modified lignin and the phenols are mixed.

[0059] The reaction conditions include atmospheric pressure. The reaction temperature is, for example, 60° C. or higher, preferably 80° C. or higher. The reaction temperature is, for example, 250° C. or lower, preferably 200° C. or lower. The reaction time is, for example, 0.5 hours or longer, preferably 1 hour or longer. The reaction time is, for example, 10 hours or shorter, preferably 5 hours or shorter.

[0060] This reaction results in the PEG-modified lignin being modified with phenols, specifically, the aliphatic hydroxyl groups in the PEG-modified lignin molecule being replaced with phenols.

[0061] In the above reaction, excess phenols remain as unreacted components, and therefore the PEG-modified lignin-phenol composition obtained by the above reaction contains a reaction product of the PEG-modified lignin and phenols (PEG-modified lignin modified with phenols) and free phenols.

[0062] Next, in this method, the PEG-modified lignin-phenol composition obtained above (i.e., containing PEG-modified lignin modified with phenols and free phenols) is reacted with aldehydes.

[0063] In this reaction, the mixing ratio of the aldehydes is, for example, 5 parts by mass or more, preferably 10 parts by mass or more, and for example, 35 parts by mass or less, preferably 30 parts by mass or less, per 100 parts by mass of the phenols (the phenols used as raw materials in the above reaction).

[0064] In this reaction, if necessary, the above-mentioned acid catalyst can be added in an appropriate ratio.

[0065] The reaction conditions include atmospheric pressure. The reaction temperature is, for example, 50° C. or higher, preferably 80° C. or higher. The reaction temperature is, for example, 200° C. or lower, preferably 180° C. or lower. The reaction time is, for example, 1 hour or longer, preferably 2 hours or longer. The reaction time is, for example, 20 hours or shorter, preferably 15 hours or shorter.

[0066] This causes the PEG-modified lignin-phenol composition to react with the aldehydes, resulting in a reaction product, a novolak compound of the PEG-modified lignin (PEG-modified lignin-novolak resin).

[0067] [PEG-modified lignin-resole resin] The PEG-modified lignin-resol resin (resole product of PEG-modified lignin) is a resol-type phenolic resin modified by PEG-modified lignin. More specifically, the PEG-modified lignin-resol resin (resole product of PEG-modified lignin) contains a reaction product of the PEG-modified lignin, the phenols, and the aldehydes (and the ketones). Preferably, the PEG-modified lignin-resol resin (resole product of PEG-modified lignin) is composed of a reaction product of the PEG-modified lignin, the phenols, and the aldehydes (and the ketones).

[0068] To react the PEG-modified lignin, phenols, and aldehydes (and optionally ketones (hereinafter the same)), the above components (PEG-modified lignin, phenols, and aldehydes) are mixed and heated in the presence of an alkaline catalyst (described below).

[0069] In this reaction, the mixing ratio of the phenols is, for example, 30 parts by mass or more, preferably 50 parts by mass or more, and more preferably 100 parts by mass or more, relative to 100 parts by mass of the PEG-modified lignin. The mixing ratio of the phenols is, for example, 1000 parts by mass or less, preferably 500 parts by mass or less, more preferably 350 parts by mass or less, and even more preferably 200 parts by mass or less, relative to 100 parts by mass of the PEG-modified lignin.

[0070] In other words, the blending ratio of the PEG-modified lignin is, for example, 10 parts by mass or more, preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more, relative to 100 parts by mass of the phenols. The blending ratio of the PEG-modified lignin is, for example, 300 parts by mass or less, preferably 200 parts by mass or less, more preferably 100 parts by mass or less, even more preferably less than 70 parts by mass, and particularly preferably 60 parts by mass or less, relative to 100 parts by mass of the phenols.

[0071] The mixing ratio of the aldehydes relative to 100 parts by mass of the phenols is, for example, 35 parts by mass or more, preferably 40 parts by mass or more.The mixing ratio of the aldehydes relative to 100 parts by mass of the phenols is, for example, 90 parts by mass or less, preferably 60 parts by mass or less.

[0072] The mixing ratio of the aldehydes is, for example, 1.5 parts by mass or more, preferably 3 parts by mass or more, relative to 100 parts by mass of the PEG-modified lignin. The mixing ratio of the aldehydes is, for example, 350 parts by mass or less, preferably 300 parts by mass or less, relative to 100 parts by mass of the PEG-modified lignin.

[0073] In this reaction, an alkali catalyst is added, that is, the above components react in the presence of an alkali catalyst.

[0074] Examples of the alkali catalyst include metal hydroxides and amines. Examples of the metal hydroxide include sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, and magnesium hydroxide. Examples of the amines include dimethylamine, triethylamine, butylamine, dibutylamine, tributylamine, diethylenetriamine, dicyandiamide, N,N-dimethylbenzylamine, aniline, 1,5-naphthalenediamine, and ammonia. These can be used alone or in combination of two or more.

[0075] The mixing ratio of the alkali catalyst relative to 100 parts by mass of the phenols is, for example, 0.1 parts by mass or more, preferably 0.3 parts by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass or less.

[0076] The timing of adding the alkaline catalyst is not particularly limited. For example, the alkaline catalyst may be added in advance to at least one of the PEG-modified lignin, the phenols, and the aldehydes. The alkaline catalyst may be added simultaneously when the PEG-modified lignin, the phenols, and the aldehydes are mixed. Furthermore, the alkaline catalyst may be added after the PEG-modified lignin, the phenols, and the aldehydes are mixed.

[0077] The reaction conditions include atmospheric pressure. The reaction temperature is, for example, 50° C. or higher, preferably 80° C. or higher. The reaction temperature is, for example, 200° C. or lower, preferably 180° C. or lower. The reaction time is, for example, 1 hour or longer, preferably 2 hours or longer. The reaction time is, for example, 20 hours or shorter, preferably 15 hours or shorter.

[0078] This allows the PEG-modified lignin to react with phenols and aldehydes in the presence of an alkali catalyst, resulting in a resol of the PEG-modified lignin (PEG-modified lignin-resol resin) as the reaction product.

[0079] In the reaction of the PEG-modified lignin, the phenols, and the aldehydes, the above components may be mixed together and reacted together as described above, or the above components may be mixed in sequence and reacted in sequence. Preferably, the above components are mixed together and reacted in sequence.

[0080] [Lignin resin content] The lignin-based resins can be used alone or in combination of two or more kinds.

[0081] From the viewpoint of heat resistance, it is preferable to use PEG-modified lignin alone.

[0082] From the viewpoint of heat resistance, it is preferable to use a novolak compound of PEG-modified lignin (PEG-modified lignin-novolak resin) alone.

[0083] From the viewpoint of heat resistance, it is preferable to use a resol product of PEG-modified lignin (PEG-modified lignin-resol resin) alone.

[0084] Furthermore, from the viewpoint of adhesion, a resol product of PEG-modified lignin (PEG-modified lignin-resol resin) is preferably used, and more preferably, a resol product of PEG-modified lignin (PEG-modified lignin-resol resin) is used alone.

[0085] The content of the lignin-based resin is, for example, 1 mass% or more, preferably 5 mass% or more, more preferably 10 mass% or more, and even more preferably 15 mass% or more, based on the total solid content of the curable resin composition. The content of the lignin-based resin is, for example, 95 mass% or less, preferably 90 mass% or less, more preferably 80 mass% or less, and even more preferably 70 mass% or less, based on the total solid content of the curable resin composition.

[0086] The total solid content of the curable resin composition is the total amount of components excluding the solvent (described later). The total solid content of the curable resin composition preferably indicates the sum of the mass of the lignin-based resin, the mass of the reactive silane coupling agent, and the mass of the catalyst (described later) (hereinafter the same).

[0087] (2) Reactive silane coupling agents The reactive silane coupling agent is a compound having at least one reactive functional group and at least one alkoxysilyl group. The reactive functional group is a functional group capable of reacting with the hydroxyl group of the lignin-based resin. Examples of the reactive functional group include an epoxy group, an amino group, an isocyanate group, a mercapto group, a vinyl group, a styryl group, a methacryl group, an acrylic group, an isocyanurate group, a ureido group, and an acid anhydride group. These are used alone or in combination of two or more kinds. Examples of the reactive functional group include preferably an epoxy group, an amino group, an isocyanate group, and a mercapto group, and more preferably an epoxy group.

[0088] That is, the reactive functional group preferably contains at least one selected from the group consisting of an epoxy group, an amino group, an isocyanate group, and a mercapto group, more preferably contains an epoxy group, and further preferably consists of an epoxy group.

[0089] When the reactive functional group contains an epoxy group, the reactive silane coupling agent may be, for example, an epoxy group-containing silane coupling agent. The epoxy group-containing silane coupling agent may be, for example, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylethyldiethoxysilane. These may be used alone or in combination of two or more kinds. The epoxy group-containing silane coupling agent may preferably be, for example, 3-glycidoxypropyltrimethoxysilane.

[0090] When the reactive functional group contains an amino group, the reactive silane coupling agent may be, for example, an amino group-containing silane coupling agent.The amino group-containing silane coupling agent may be, for example, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, and 3-ureidopropyltrialkoxysilane.These may be used alone or in combination of two or more kinds.

[0091] When the reactive functional group contains an isocyanate group, the reactive silane coupling agent may be, for example, an isocyanate group-containing silane coupling agent. The isocyanate group-containing silane coupling agent may be, for example, 3-isocyanatepropyltriethoxysilane. These may be used alone or in combination of two or more kinds.

[0092] When the reactive functional group contains a mercapto group, the reactive silane coupling agent may be, for example, a mercapto group-containing silane coupling agent. The mercapto group-containing silane coupling agent may be, for example, 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. These may be used alone or in combination of two or more kinds.

[0093] The reactive silane coupling agent can be used alone or in combination of two or more kinds. As the reactive silane coupling agent, preferably, an epoxy group-containing silane coupling agent is used, and more preferably, 3-glycidoxypropyltrimethoxysilane is used.

[0094] The content of the reactive silane coupling agent is, for example, 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more, based on the total solid content of the curable resin composition. The content of the reactive silane coupling agent is, for example, 95% by mass or less, preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less, based on the total solid content of the curable resin composition.

[0095] The content of the reactive silane coupling agent is, for example, 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of the lignin-based resin. The content of the reactive silane coupling agent is, for example, 100 parts by mass or less, preferably 80 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 30 parts by mass or less, relative to 100 parts by mass of the lignin-based resin.

[0096] The equivalent ratio of the reactive functional group in the reactive silane coupling agent to the hydroxyl group in the lignin resin (reactive functional group / hydroxyl group) is, for example, 0.8 or more, preferably 1.0 or more. The equivalent ratio of the reactive functional group in the reactive silane coupling agent to the hydroxyl group in the lignin resin (reactive functional group / hydroxyl group) is, for example, 100 or less, preferably 80 or less, more preferably 50 or less.

[0097] In particular, when the lignin-based resin is a PEG-modified lignin (non-novolac and non-resole), the equivalent ratio of the reactive functional groups in the reactive silane coupling agent to the hydroxyl groups in the lignin-based resin (reactive functional groups / hydroxyl groups) is more preferably 10 or more, and particularly preferably 30 or more.

[0098] In addition, when the lignin-based resin is a novolak compound of PEG-modified lignin (PEG-modified lignin-novolak resin), the equivalent ratio of the reactive functional group in the reactive silane coupling agent to the hydroxyl group in the lignin-based resin (reactive functional group / hydroxyl group) is more preferably 1.5 or more. In addition, the equivalent ratio of the reactive functional group in the reactive silane coupling agent to the hydroxyl group in the lignin-based resin (reactive functional group / hydroxyl group) is further preferably 10 or less, particularly preferably 5 or less.

[0099] In addition, when the lignin-based resin is a resol of PEG-modified lignin (PEG-modified lignin-resol resin), the equivalent ratio of the reactive functional group in the reactive silane coupling agent to the hydroxyl group in the lignin-based resin (reactive functional group / hydroxyl group) is more preferably 1.2 or more. In addition, the equivalent ratio of the reactive functional group in the reactive silane coupling agent to the hydroxyl group in the lignin-based resin (reactive functional group / hydroxyl group) is further preferably 5.0 or less, particularly preferably less than 2.0, particularly preferably 1.6 or less.

[0100] (3) Catalyst The curable resin composition may contain a catalyst as an optional component, if necessary. Preferably, the curable resin composition contains a catalyst. Examples of the catalyst include a reaction catalyst in the reaction between the hydroxyl group of the lignin-based resin and the reactive functional group of the reactive silane coupling agent.

[0101] The reaction catalyst is selected, for example, according to the type of reactive functional group. More specifically, when the reactive functional group contains an epoxy group, the reaction catalyst may be, for example, an amine type catalyst, an amide type catalyst, an imidazole type catalyst, and an acid anhydride type catalyst, and preferably an imidazole type catalyst. In other words, when the reactive functional group contains an epoxy group, the curable resin composition preferably contains an imidazole type catalyst. Examples of the imidazole type catalyst include 1-imidazole, 1-vinylimidazole, 1-ethylimidazole, 2-methylimidazole, 1-benzyl-2-phenylimidazole, 2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole. These may be used alone or in combination of two or more kinds. A preferred imidazole type catalyst is 2-ethyl-4-methylimidazole.

[0102] The catalyst content is, for example, 0.1 mass% or more, preferably 0.3 mass% or more, more preferably 0.5 mass% or more, based on the total solid content of the curable resin composition. The catalyst content is, for example, 5 mass% or less, preferably 2 mass% or less, more preferably 1 mass% or less, based on the total solid content of the curable resin composition.

[0103] The catalyst content is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the lignin-based resin. The catalyst content is, for example, 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of the lignin-based resin.

[0104] (4) Solvent The curable resin composition may contain a solvent as an optional component, if necessary. Preferably, the curable resin composition contains a solvent. The solvent is not particularly limited, and may be a known organic solvent.

[0105] More specifically, examples of the solvent include petroleum-based hydrocarbons, aromatic hydrocarbons, ethers, ketones, esters, and aprotic polar solvents. Examples of the petroleum-based hydrocarbons include hexane and mineral spirits. Examples of the aromatic hydrocarbons include benzene, toluene, and xylene. Examples of the ethers include dimethyl ether, diethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran. Examples of the ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone. Examples of the esters include methyl acetate, ethyl acetate, butyl acetate, γ-butyrolactone, and propylene glycol monomethyl ether acetate. Examples of the aprotic polar solvents include N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, and pyridine. These can be used alone or in combination of two or more. The solvent is appropriately selected depending on the type of lignin-based resin and the type of reactive silane coupling agent. As the solvent, preferably, aprotic polar solvent and ether are included. As the aprotic polar solvent, preferably, N,N-dimethylacetamide is included. As the ether, preferably, tetrahydrofuran is included.

[0106] The content of the solvent is not particularly limited, but is, for example, 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, based on the total amount of the curable resin composition (total amount of solid content and solvent). The content of the solvent is, for example, 95% by mass or less, preferably 90% by mass or less, more preferably 80% by mass or less, based on the total amount of the curable resin composition (including the solvent).

[0107] In other words, when the curable resin composition contains a solvent, the solid content concentration of the curable resin composition is, for example, 5 mass% or more, preferably 10 mass% or more, more preferably 20 mass% or more. When the curable resin composition contains a solvent, the solid content concentration of the curable resin composition is, for example, 90 mass% or less, preferably 70 mass% or less, more preferably 50 mass% or less.

[0108] The content of the solvent is, for example, 100 parts by mass or more, preferably 200 parts by mass or more, more preferably 300 parts by mass or more, and even more preferably 500 parts by mass or more, relative to 100 parts by mass of the lignin-based resin. The content of the solvent is, for example, 5000 parts by mass or less, preferably 3000 parts by mass or less, more preferably 2000 parts by mass or less, and even more preferably 1000 parts by mass or less, relative to 100 parts by mass of the lignin-based resin.

[0109] (5) Other ingredients The curable resin composition may further contain other resins. The other resins are resins other than the above-mentioned lignin-based resins. Examples of the other resins include known thermosetting resins, more specifically, for example, melamine resins, epoxy resins, polyimide resins, phenolic resins, benzoxazine resins, urea resins, and unsaturated polyester resins. These may be used alone or in combination of two or more kinds. The content ratio of the other resins is appropriately set according to the purpose and application within a range that does not impair the excellent effects of the present invention.

[0110] The curable resin composition may further contain additives. Examples of additives include curing agents, fillers, lubricants, colorants, plasticizers, stabilizers, and release agents. These may be used alone or in combination of two or more. The timing of adding the additives is not particularly limited and is appropriately set according to the purpose and application. The content ratio of the additives is appropriately set according to the purpose and application within a range that does not impair the excellent effects of the present invention.

[0111] (6) Method for producing curable resin composition The method for producing the curable resin composition is not particularly limited. For example, a lignin-based resin and a reactive silane coupling agent are mixed by a known method. If necessary, a catalyst, a solvent and / or an additive are mixed at an appropriate timing. This produces a curable resin composition.

[0112] The order of mixing each component is not particularly limited. For example, first, a lignin-based resin and a solvent are mixed to prepare a resin solution. Then, a reactive silane coupling agent and a catalyst are added to the resin solution and mixed. This results in a curable resin composition containing a lignin-based resin, a reactive silane coupling agent, a catalyst, and a solvent.

[0113] 2.Cured product The cured product of the curable resin composition is an organic-inorganic hybrid material having both an organic structure (described later) and an inorganic structure (described later), which will be described in detail later. The cured product is produced by curing the curable resin composition.

[0114] The method for curing the curable resin composition is not particularly limited. For example, the curable resin composition is dried, and then the dried product of the curable resin composition is heated (heat-treated).

[0115] Drying conditions are not particularly limited and are appropriately set. The drying temperature is, for example, 10°C or higher, preferably 20°C or higher, and more preferably 30°C or higher. The drying temperature is, for example, less than 50°C, preferably 45°C or lower, and more preferably 40°C or lower. The drying time is, for example, 10 minutes or more, preferably 30 minutes or more, and more preferably 1 hour or more. The drying time is, for example, 7 days or less, preferably 3 days or less, and more preferably 1 day or less.

[0116] The heating (heat treatment) conditions are not particularly limited and are set appropriately. The heating temperature is, for example, 50°C or higher, preferably 80°C or higher, and more preferably 110°C or higher. The heating temperature is, for example, 300°C or lower, preferably 250°C or lower, and more preferably 200°C or lower. The heating time is, for example, 10 minutes or longer, preferably 1 hour or longer, and more preferably 2 hours or longer. The heating time is, for example, 24 hours or shorter, preferably 12 hours or shorter, and more preferably 6 hours or shorter.

[0117] By the above drying and heating (heat treatment), a cured product of the curable resin composition is obtained.

[0118] More specifically, the drying causes the hydroxyl group of the lignin resin to react with the reactive functional group of the reactive silane coupling agent, and the reactive silane coupling agent is added to the lignin resin. As a result, the reaction product formed by the reaction of the lignin resin with the reactive silane coupling agent is contained in the dried material. In addition, the drying causes a part of the alkoxysilyl group derived from the reactive silane coupling agent to condense and form a polysiloxane structure (-Si-O-Si-).

[0119] Furthermore, the reaction between the lignin-based resin and the reactive silane coupling agent proceeds due to the above heating (heat treatment). As a result, the addition of the reactive silane coupling agent to the lignin-based resin is completed. Furthermore, the above heating (heat treatment) proceeds with the condensation of the alkoxysilyl group. As a result, the formation of the polysiloxane structure (-Si-O-Si-) is completed. In other words, the drying and heating (heat treatment) of the curable resin composition crosslinks the curable resin composition, and a cured product is obtained.

[0120] That is, the above-mentioned cured product contains a reaction product (organic structure) formed by the reaction of the hydroxyl group of the lignin-based resin with the reactive functional group of the reactive silane coupling agent. The above-mentioned reaction product also contains a polysiloxane structure (inorganic structure) formed by condensation of the alkoxysilyl group of the reactive silane coupling agent. That is, the cured product of the curable resin composition is an organic-inorganic hybrid material (a material having both an organic structure and an inorganic structure).

[0121] The cured product may be treated, if necessary, by a known method, such as aging treatment and surface coating treatment.

[0122] 3. Coating composition and coating film The above-mentioned curable resin composition and the above-mentioned cured product are suitably used in various coating fields.

[0123] More specifically, the curable resin composition is suitably used as a coating composition. That is, the coating composition contains the curable resin composition, and preferably consists of the curable resin composition.

[0124] The coating composition (curable resin composition) is applied to any object to be coated by any method. The application method and application amount are appropriately set according to the purpose and application. The coating composition (curable resin composition) is dried and heated (heat treated) on the surface of the object to be coated by the above-mentioned method. This causes the coating composition to harden.

[0125] As a result, a coating film is formed on the surface of the object to be coated as a cured product of the coating composition (curable resin composition). That is, the coating film contains the cured product, and preferably consists of the cured product.

[0126] 4. Effects In the above curable resin composition and the above coating composition, the lignin-based resin contains at least one selected from the group consisting of lignin modified with polyethylene glycol, a novolak product of lignin modified with polyethylene glycol, and a resol product of lignin modified with polyethylene glycol. Therefore, the above curable resin composition can produce a cured product having excellent heat resistance. In addition, the above cured product has excellent heat resistance.

[0127] Moreover, the cured product and the coating film have excellent heat resistance since they are obtained by curing the curable resin composition.

[0128] Therefore, the above-mentioned curable resin composition and coating composition are preferably used as a coating composition for coating the surfaces of, for example, glass, metal, ceramics, and plastics. Also, the above-mentioned cured product and coating film are preferably used as a coating film for coating the surfaces of glass, metal, ceramics, and plastics. In particular, the above-mentioned curable resin composition, coating composition, cured product, and coating film are preferably used in electric and electronic materials, paints, automobiles, and resin modification applications.

[0129] 5. Resole-type phenolic resin and curable resin composition The above-mentioned PEG-modified lignin-resol resin can be used alone as a curable resin composition. Hereinafter, the PEG-modified lignin-resol resin may be simply referred to as a resol-type phenolic resin.

[0130] The resol type phenolic resin includes a reaction product obtained by reacting the PEG-modified lignin, the phenols, and the aldehydes under the alkaline catalyst. Preferably, the resol type phenolic resin is a reaction product obtained by reacting the PEG-modified lignin, the phenols, and the aldehydes under the alkaline catalyst. The resol type phenolic resin is obtained, for example, by the above-mentioned method for producing a PEG-modified lignin-resol resin.

[0131] The resol type phenolic resin contains lignin modified with polyethylene glycol as a reaction raw material, and therefore can produce a cured product having excellent adhesion.

[0132] The curable resin composition may contain the above-mentioned resol-type phenolic resin (PEG-modified lignin-resol resin) as an essential component. For example, the curable resin composition may contain the above-mentioned solvent and / or the above-mentioned additive as an optional component. The blending ratio and blending timing are appropriately set according to the purpose and application.

[0133] The curable resin composition may further contain other resins. The other resins are resins other than the resol-type phenolic resins. Examples of the other resins include known thermosetting resins, more specifically, for example, melamine resins, epoxy resins, polyimide resins, phenolic resins, benzoxazine resins, urea resins, and unsaturated polyester resins. These may be used alone or in combination of two or more kinds. The content ratio of the other resins is appropriately set according to the purpose and application within a range that does not impair the excellent effects of the present invention.

[0134] The curable resin composition is widely used in various industrial fields. For example, the curable resin composition can be used as a coating agent.

[0135] When the curable resin composition is used as a coating agent, the curable resin composition contains, for example, the above-mentioned resol-type phenolic resin (PEG-modified lignin-resol resin) (and other resins, if necessary (the same applies below)) and a solvent.

[0136] Examples of the solvent include the above-mentioned petroleum-based hydrocarbons, the above-mentioned aromatic hydrocarbons, the above-mentioned ethers, the above-mentioned ketones, the above-mentioned esters, and the above-mentioned aprotic polar solvents. These can be used alone or in combination of two or more kinds. The solvent is preferably an ether, and more preferably tetrahydrofuran.

[0137] When the curable resin composition is used as a coating agent, the resol type phenolic resin (PEG-modified lignin-resol resin) is dissolved and / or dispersed in the solvent by a known method. As a result, a solution and / or dispersion of the resol type phenolic resin is obtained. The solution and / or dispersion of the resol type phenolic resin is used as a coating agent.

[0138] In the solution and / or dispersion of the resol type phenolic resin, the solid content concentration of the resol type phenolic resin is, for example, 1 to 50 mass %, preferably 10 to 30 mass %.

[0139] The method of using the coating agent is not particularly limited. For example, the coating agent is applied to an arbitrary substrate and dried to obtain a dried coating film. The dried coating film is then heated and cured to obtain a cured film (coating film). The curing conditions are not particularly limited and are appropriately set depending on the purpose and application. For example, the curing temperature (heating temperature) is, for example, 80 to 300°C, preferably 100 to 250°C, and more preferably 150 to 200°C. The curing time (heating time) is, for example, 0.1 to 48 hours, preferably 1 to 24 hours, and more preferably 2 to 12 hours.

[0140] The cured film thus obtained is a cured product of the above-mentioned curable resin composition, and therefore has excellent adhesion.

[0141] The curable resin composition can be used as a molding material, for example, a mold molding material.

[0142] When the curable resin composition is used as a molding material, the curable resin composition contains, for example, the above-mentioned resol-type phenolic resin (PEG-modified lignin-resol resin) and the above-mentioned additives. These can be used alone or in combination of two or more kinds.

[0143] More specifically, when the curable resin composition is used as a molding material, for example, a resol-type phenolic resin and an additive are mixed (kneaded) by a known method. The kneading method is not particularly limited, and a known kneader is used. Examples of the kneader include a single-screw extruder, a multi-screw extruder, a roll kneader, a kneader, a Henschel mixer, and a Banbury mixer. The kneading conditions are appropriately set depending on the purpose and application.

[0144] The curable resin composition (molding material) is suitably used for producing a molded product. More specifically, the curable resin composition (molding material) is molded by a known molding method. The molding conditions are not particularly limited and are appropriately set according to the purpose and application. For example, the molding temperature (heating temperature) is, for example, 80 to 300°C, preferably 100 to 250°C, and more preferably 150 to 200°C. The molding time (heating time) is, for example, 0.1 to 48 hours, preferably 1 to 24 hours, and more preferably 2 to 12 hours.

[0145] The molded article thus obtained is a cured product of the above-mentioned curable resin composition, and therefore has excellent adhesion.

[0146] The curable resin composition can also be used as a resin in an impregnated plate. When the curable resin composition is used as a resin in an impregnated plate, the curable resin composition is, for example, impregnated into a known substrate (for example, paper and cloth) and cured. The curing conditions are, for example, the same as the above molding conditions. This results in an impregnated plate (a substrate impregnated with phenolic resin and cured).

[0147] The impregnated board thus obtained contains the cured product of the curable resin composition, and therefore has excellent adhesion. EXAMPLES

[0148] Next, the present invention will be described based on examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are based on mass unless otherwise specified. In addition, the specific numerical values ​​of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit value (numeric value defined as "less than or equal to" or "less than") or lower limit value (numeric value defined as "more than or equal to" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Form for carrying out the invention".

[0149] [A Organic-inorganic hybrid materials] 1. PEG-modified lignin Production Example 1 (PEG200 modified lignin) Lignin modified with polyethylene glycol having a number average molecular weight of 200 (hereinafter referred to as PEG200-modified lignin) was produced by the following method.

[0150] That is, 230 parts by mass of commercially available polyethylene glycol with a number average molecular weight of 200 (hereinafter, PEG200) and 0.69 parts by mass of sulfuric acid as an acid catalyst (0.3 parts by mass for 100 parts by mass of PEG200) were placed in a reaction vessel and stirred. Next, 46 parts by mass of bone-dried cedar wood flour were placed in the reaction vessel, heated to 140°C under normal pressure, and reacted for 90 minutes while stirring. Next, the reaction vessel was cooled, and after confirming that the temperature was 40°C or less, 280 parts by mass of sodium hydroxide (0.2 mol / L) was added and stirred for 30 minutes. Next, the obtained solid component (pulp) was removed by a filter press, and the solution component was collected. Next, sulfuric acid was added to the obtained solution component, and the pH was adjusted to 2.0. This resulted in a suspension of PEG200-modified lignin. Then, the PEG200-modified lignin was collected by centrifugation.

[0151] The hydroxyl equivalent of the PEG200-modified lignin was calculated based on Table 1 in the literature "ACS Sustainable Chem. Eng. 2016, 4, 2861-2868." As a result, the hydroxyl equivalent of the PEG200-modified lignin was 0.000625 (mol / g).

[0152] Production Example 2 (PEG400 modified lignin) A lignin modified with polyethylene glycol having a number average molecular weight of 400 (hereinafter, PEG400-modified lignin) was obtained in the same manner as in Production Example 1, except that polyethylene glycol having a number average molecular weight of 400 (hereinafter, PEG400) was used instead of polyethylene glycol having a number average molecular weight of 200.

[0153] The hydroxyl equivalent of the PEG400-modified lignin was calculated based on Table 1 in the literature "ACS Sustainable Chem. Eng. 2016, 4, 2861-2868." As a result, the hydroxyl equivalent of the PEG400-modified lignin was 0.000417 (mol / g).

[0154] Production Example 3 (PEG600 modified lignin) A lignin modified with polyethylene glycol having a number average molecular weight of 600 (hereinafter, PEG600-modified lignin) was obtained in the same manner as in Production Example 1, except that polyethylene glycol having a number average molecular weight of 600 (hereinafter, PEG600) was used instead of polyethylene glycol having a number average molecular weight of 200.

[0155] The hydroxyl equivalent of the PEG600-modified lignin was calculated based on Table 1 in the literature "ACS Sustainable Chem. Eng. 2016, 4, 2861-2868. As a result, the hydroxyl equivalent of the PEG600-modified lignin was 0.000313 (mol / g).

[0156] 2. PEG-modified lignin-novolac resin Production Example 4 (PEG200 modified lignin-novolac resin) 493.5 parts by mass of phenol was placed in a flask and heated to about 50° C. to liquefy the phenol, and then 150 parts by mass of the PEG200-modified lignin of Production Example 1 was added.

[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. The contents of the flask were then heated to 110° C. at 0.5° C. / min, and reacted at 110° C. for 1.5 hours. The contents of the flask were then heated to 120° C. at 0.5° C. / min, and reacted at 120° C. for 2 hours.

[0158] After the reaction, 2300 parts by mass of water was added to the flask, and the contents of the flask were vigorously stirred. Next, the contents of the flask were left to stand, and water, oxalic acid, and phenol were removed by decantation. Furthermore, while adding water to the flask, reduced-pressure distillation was performed under conditions of 120°C and 0.08 MPa to remove residual phenol. The reduced-pressure distillation was repeated until the residual phenol rate was 1% or less. As a result, a novolac product of PEG200-modified lignin (PEG200 lignin-novolac resin) was obtained.

[0159] The hydroxyl equivalent of the PEG200 lignin-novolac resin was calculated based on Table 1 in the literature "ACS Sustainable Chem. Eng. 2016, 4, 2861-2868." As a result, the hydroxyl equivalent of the PEG200 lignin-novolac resin was 0.007254 (mol / g).

[0160] Manufacturing Examples 5-12 PEG-modified lignin-novolac resins were obtained in the same manner as in Production Example 4, except that the formulation was changed to that shown in Table 1. The hydroxyl equivalent of each PEG-modified lignin-novolac resin was calculated in the same manner as in Production Example 4. The results are shown in Table 1.

[0161] As shown in Table 1, the PEG-modified lignin-novolac resins of Production Examples 4 to 12 were designated P200LN-1 to 3, P400LN-1 to 3, and P600LN-1 to 3, respectively, based on the molecular weight of PEG and the blending recipe.

[0162] 3. Curable resin composition and cured product (1) Examples 1 to 12 According to the formulations shown in Table 2, curable resin compositions and cured products thereof were prepared.

[0163] That is, 1.125 parts by mass of PEG-modified lignin (Production Examples 1 to 3) or PEG-modified lignin-novolac resin (Production Examples 4 to 12) was dissolved in 22.5 parts by mass of tetrahydrofuran (THF, manufactured by Nacalai Tesque), thereby obtaining a resin solution.

[0164] Next, 5.31 parts by mass of 3-glycidoxypropyltrimethoxysilane (epoxy group-containing silane coupling agent, KBM-403, Shin-Etsu Chemical Co., Ltd.) was added to the resin solution, and 0.13 parts by mass of 2-ethyl-4-methylimidazole (catalyst, 2Et4Mz, Shikoku Chemical Industry Co., Ltd.) was further added and mixed. This resulted in a curable resin composition.

[0165] Next, the curable resin composition was placed in a petri dish made of Teflon (registered trademark) and dried at 40° C. for 24 hours. Thereafter, the dried product of the curable resin composition was heated at 150° C. for 2 hours to be cured. As a result, a cured product of the curable resin composition was obtained.

[0166] Examples 13 to 24 Curable resin compositions and cured products thereof were obtained in the same manner as in Example 1, except that the blending formulation was changed to that shown in Table 3.

[0167] 4. PEG-modified lignin-resole resin Production Example 13 (PEG600 modified lignin-resole resin) Into a three-necked 1 L separable flask equipped with a reflux condenser, a thermometer, a stirrer and a dropping funnel, 141 parts by mass (1.5 parts by mole) of phenol was placed at 40°C.

[0168] Next, 42.3 parts by mass of PEG600-modified lignin (Production Example 3) was added to the separable flask at 40° C., and the contents of the flask were stirred. The amount of PEG600-modified lignin (Production Example 3) was 30 parts by mass relative to 100 parts by mass of phenol.

[0169] Next, 186 parts by mass of 37% formalin (aqueous formaldehyde solution, 68.8 parts by mass (2.3 mol parts) of formaldehyde) was added to the separable flask. The blending ratio of formaldehyde was 48.8 parts by mass with respect to 100 parts by mass of phenol.

[0170] Furthermore, triethylamine was added as an alkali catalyst to the separable flask and stirred to homogenize the contents of the separable flask. The amount of the alkali catalyst added was 2 parts by mass with respect to 100 parts by mass of phenol.

[0171] Next, the temperature of the contents of the separable flask was gradually raised (over about 1 hour) to 80°C. The contents of the separable flask were reacted at 80°C for 3 hours. Thereafter, the water in the separable flask was removed with an evaporator, and the contents of the separable flask were dried under reduced pressure. As a result, a PEG600-modified lignin-resol resin was obtained as a reaction product.

[0172] The hydroxyl equivalent of the PEG600 lignin-resole resin was calculated based on Table 1 in the literature "ACS Sustainable Chem. Eng. 2016, 4, 2861-2868." As a result, the hydroxyl equivalent of the PEG600 lignin-resole resin was 0.007792 (mol / g).

[0173] Manufacturing Examples 14-18 PEG-modified lignin-resol resins were obtained in the same manner as in Production Example 13, except that the formulation was changed to that shown in Table 4. The hydroxyl equivalent of each PEG-modified lignin-resol resin was calculated in the same manner as in Production Example 13. The results are shown in Table 4.

[0174] As shown in Table 4, the PEG-modified lignin-resol resins of Production Examples 13 to 17 were designated PEG600LR-1 to 3, P400LR-1, and P200LR-1, respectively, based on the molecular weight of PEG and the blending recipe.

[0175] In Production Example 18, a resol resin was obtained by reacting phenol with formaldehyde without blending PEG-modified lignin. The resol resin of Production Example 18 was called PR (Pure Resol).

[0176] 5. Curable resin composition and cured product (2) Examples 25 to 29 A curable resin composition was obtained in the same manner as in Example 1, except that the compounding formulation was changed to that shown in Table 5.

[0177] Next, the curable resin composition was placed in a Teflon (registered trademark) petri dish and dried at 40° C. for 24 hours. Thereafter, the dried product of the curable resin composition was heated at 160° C. for 1 hour, then at 180° C. for 1 hour, and further heated at 200° C. for 2 hours to be cured. As a result, a cured product of the curable resin composition was obtained.

[0178] 6. Check the reaction (1) IR measurement The reaction of each component in Examples 1, 4, and 25 was confirmed by the following method: The IR spectra of the curable resin composition (20° C.), the dried product of the curable resin composition (40° C.), and the cured product of the curable resin composition (150° C.) were measured by a Fourier transform infrared spectrophotometer.

[0179] [Curable resin composition (20℃)] In the IR spectrum of the curable resin composition (20 °C), an absorption peak (3350 to 3400 cm) derived from the hydroxyl group of the lignin-based resin was observed. -1 ) was observed.

[0180] In addition, in the IR spectrum of the curable resin composition (20°C), an absorption peak (907 cm) derived from the epoxy group of the epoxy group-containing silane coupling agent was observed. -1 ) was observed.

[0181] In addition, in the IR spectrum of the curable resin composition (20°C), an absorption peak (2840 cm) derived from the alkoxysilyl group (Si-O-CH group) of the epoxy group-containing silane coupling agent was observed. -1 ) was observed.

[0182] In addition, in the IR spectrum of the curable resin composition (20°C), an absorption peak (1020 cm) derived from the polysiloxane structure (-Si-O-Si-) was observed. -1 and 1095 cm -1 ) was not confirmed.

[0183] [Dry product of curable resin composition (40°C)] In the IR spectrum of the dried product (40 ° C.) of the curable resin composition, an absorption peak (3350 to 3400 cm ) derived from the hydroxyl group of the lignin-based resin was observed. -1 ) was observed. The peak intensity was lower than the peak intensity of the curable resin composition (20° C.).

[0184] In addition, in the IR spectrum of the dried product (40°C) of the curable resin composition, an absorption peak (907 cm) derived from the epoxy group of the epoxy group-containing silane coupling agent was observed. -1 ) was observed. The peak intensity was lower than the peak intensity of the curable resin composition (20° C.).

[0185] In addition, in the IR spectrum of the dried product (40°C) of the curable resin composition, an absorption peak (2840 cm) derived from the alkoxysilyl group (Si-O-CH group) of the epoxy group-containing silane coupling agent was observed. -1 ) was observed. The peak intensity was lower than the peak intensity of the curable resin composition (20° C.).

[0186] Furthermore, in the IR spectrum of the dried product (40°C) of the curable resin composition, an absorption peak (1020 cm) derived from the polysiloxane structure (-Si-O-Si-) was observed. -1 and 1095 cm -1 ) was confirmed.

[0187] [Cured product of curable resin composition (150°C)] In the IR spectrum of the cured product (150 °C) of the curable resin composition, an absorption peak (3350 to 3400 cm) derived from the hydroxyl group of the lignin-based resin was observed. -1 ) was observed. The peak intensity was lower than the peak intensity of the curable resin composition (20° C.).

[0188] In addition, in the IR spectrum of the cured product (150 °C) of the curable resin composition, an absorption peak (907 cm) derived from the epoxy group of the epoxy group-containing silane coupling agent was observed. -1 ) was not observed. In other words, disappearance of the epoxy groups was confirmed.

[0189] In addition, in the IR spectrum of the cured product (150 °C) of the curable resin composition, an absorption peak (2840 cm) derived from the alkoxysilyl group (Si-O-CH group) of the epoxy group-containing silane coupling agent was observed. -1 ) was not observed. In other words, disappearance of the alkoxysilyl group was confirmed.

[0190] Furthermore, in the IR spectrum of the cured product (150 °C) of the curable resin composition, an absorption peak (1020 cm) derived from the polysiloxane structure (-Si-O-Si-) was observed. -1 and 1095 cm -1 ) was confirmed. The peak intensity was higher than the peak intensity of the dried product (40° C.) of the curable resin composition.

[0191] From the above, it was confirmed that the epoxy group and the hydroxyl group reacted when the curable resin composition was dried (40°C) and cured (150°C). It was also confirmed that the alkoxysilyl group (Si-O-CH3 group) condensed to form a polysiloxane structure (-Si-O-Si-) when the curable resin composition was dried (40°C) and cured (150°C).

[0192] (2) Scanning Electron Microscopy (SEM) and Element Mapping The cured products of the curable resin compositions in Examples 1, 4, and 25 were photographed by an electron microscope (SEM) and elemental mapping was performed. By observing the images, it was confirmed that the cured products did not have a phase-separated structure and had a uniform structure.

[0193] 7. Evaluation (1) Maintenance rate of storage modulus E' at high temperatures The heat resistance of the cured product of the curable resin composition obtained in each Example was evaluated by the following method.

[0194] That is, the solid dynamic viscoelasticity of the cured product was measured using Rheogel-E4000 (manufactured by UBM Co., Ltd.) The measurement conditions are shown below.

[0195] Tensile mode, frequency 1Hz, temperature range 25℃~250℃, heating rate 2℃ / min And the storage modulus E' at 100°C 100 The retention rate of the storage modulus E' at 250°C (100 x (E' 250 / E' 100 The closer the retention rate of the storage modulus E' was to 100%, the more excellent the heat resistance of the cured product was judged to be.

[0196] As Comparative Example 1, the retention rate of the storage modulus E' of a conventional material was calculated based on FIG. 3 of JP-A-2006-342270.

[0197] More specifically, based on FIG. 3 of JP-A-2006-342270, the storage modulus E' at 100°C, the storage modulus E' at 250°C, and the retention rate thereof of the material of an example (Comparative Example 1) of JP-A-2006-342270 were calculated.

[0198] As a result, the storage modulus E' of the conventional material at 100℃ 100 is about 20 (Pa x 10 8 ) The storage modulus E' of the conventional material at 250°C was 250 is approximately 2 (Pa x 10 8 The retention rate of the storage modulus E' of the conventional material (100 × (E' 250 / E' 100 )) was approximately 10%.

[0199] (2) Adhesion The curable resin compositions of Examples 25 to 29 (using PEG-modified lignin-resol resin, resin solution) were applied to a glass substrate using a #20 bar coater to obtain a coating film. The coating film was dried in an oven at 40°C for 24 hours to obtain a dried coating film. Thereafter, the dried coating film was heated at 160°C for 1 hour, then at 180°C for 1 hour, and then at 200°C for 2 hours. This thermally cured the dried coating film to obtain a cured film.

[0200] The adhesion of each cured film was evaluated according to the following criteria by a cross-cut adhesion test (JIS K5600 (1999)). The results are shown in Table 5.

[0201] Classification 0: The cured film did not peel off in any of the cross-cut areas. Category 1: Peeling of the cured film was confirmed at the intersections of the cuts. The proportion of peeled cured film (cross-cut) was less than 5% of the total cured film (cross-cut). Category 2: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 5% or more and less than 15% of the total cured film (grid). Category 3: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 15% or more and less than 35% of the total cured film (grid). Category 4: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 35% or more and less than 65% of the total cured film (grid). Category 5: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 65% or more of the total cured film (grid).

[0202] [Table 1]

[0203] [Table 2]

[0204] [Table 3]

[0205] [Table 4]

[0206] [Table 5]

[0207] [B Resole type phenolic resin] 1.Cured film Examples 30 to 34 4.0 g of the PEG-modified lignin-resol resins of Production Examples 13 to 17 shown in Table 5 was dissolved in 15 ml of tetrahydrofuran to obtain a coating agent (a solution of PEG-modified lignin-resol resin).

[0208] Comparative Example 2 Instead of the PEG-modified lignin-resol resin, the resol resin (PR, Pure Resol) of Production Example 18 was used. A coating agent (a solution of a resol resin) was obtained in the same manner as in Example 30.

[0209] 2. Evaluation (1) Adhesion The coating agents of Examples 30 to 34 and Comparative Example 2 were applied to a glass substrate using a #20 bar coater to obtain a coating film. The coating film was dried in an oven at 40°C for 24 hours to obtain a dried coating film. The dried coating film was then heated at 160°C for 1 hour, then at 180°C for 1 hour, and then at 200°C for 2 hours. This thermally cured the dried coating film to obtain a cured film.

[0210] The adhesion of each cured film was evaluated according to the following criteria by a cross-cut adhesion test (JIS K5600 (1999)). The results are shown in Table 6.

[0211] Classification 0: The cured film did not peel off in any of the cross-cut areas. Category 1: Peeling of the cured film was confirmed at the intersections of the cuts. The proportion of peeled cured film (cross-cut) was less than 5% of the total cured film (cross-cut). Category 2: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 5% or more and less than 15% of the total cured film (grid). Category 3: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 15% or more and less than 35% of the total cured film (grid). Category 4: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 35% or more and less than 65% of the total cured film (grid). Category 5: Peeling of the cured film was confirmed along the cut lines. The percentage of peeled cured film (grid) was 65% or more of the total cured film (grid).

[0212] [Table 6]

Claims

1. A lignin-based resin having a hydroxyl group; a reactive silane coupling agent having a reactive functional group capable of reacting with the hydroxyl group; Contains The lignin-based resin is Lignin modified with polyethylene glycol; a lignin novolak modified with polyethylene glycol; Resole of lignin modified with polyethylene glycol A curable resin composition comprising at least one selected from the group consisting of:

2. The novolak compound or the resol compound is Lignin modified with polyethylene glycol; Phenols and Aldehydes and The curable resin composition of claim 1 comprising the reaction product of

3. The curable resin composition according to claim 1 , wherein the polyethylene glycol has a number average molecular weight of 400 or more.

4. The curable resin composition of claim 1 , wherein the reactive functional group comprises an epoxy group.

5. The curable resin composition according to claim 1 , further comprising a reaction catalyst for the reaction between the hydroxyl group and the reactive functional group.

6. The curable resin composition according to claim 5 , wherein the reaction catalyst comprises an imidazole-type catalyst.

7. A cured product of the curable resin composition according to claim 1.

8. The composition contains a reaction product obtained by reacting the hydroxyl group of the lignin-based resin with the reactive functional group of the reactive silane coupling agent, The cured product according to claim 7 , wherein the reaction product contains a polysiloxane structure formed by condensation of alkoxysilyl groups of the reactive silane coupling agent.

9. A coating composition comprising the curable resin composition according to claim 1.

10. A coating film comprising the cured product according to claim 7.

11. Lignin modified with polyethylene glycol; Phenols and Aldehydes and and a reaction product obtained by reacting the above in the presence of an alkali catalyst.

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