Resin composition and odor suppression method for resin material

Abstract

To provide a resin composition comprising a lignin-modified phenolic resin that exhibits suppressed odor emission.SOLUTION: A resin composition comprising a sulfur-containing lignin-modified novolac-type phenolic resin, a volatile sulfur compound, and a sulfur-based gas scavenger, wherein the sulfur-containing lignin-modified novolac-type phenolic resin is a reaction product of a sulfur-containing lignin, a phenol, and an aldehyde.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition containing a sulfur-containing lignin-modified novolak-type phenol resin, and a method for suppressing the odor derived from the sulfur content of a resin material containing a sulfur-containing lignin-modified novolak-type phenol resin.

Background Art

[0002] Phenolic resins are excellent in various aspects such as heat resistance, mechanical properties, moldability, and cost among thermosetting resins, and are used in various applications such as molding materials and laminates. By the way, phenolic resins are produced from petroleum as a raw material. For this reason, the production of phenolic resins may cause global warming due to the emission of carbon dioxide. In addition, petroleum is a resource that is being depleted, and it is a major problem in terms of the stable supply of phenolic resins in the future.

[0003] In order to solve such environmental problems and problems of stable supply, in recent years, it has been demanded to convert biomass into phenolic resin products and the like as substitutes for petroleum-derived products. In particular, lignin, which is a main component of general plants, is expected to be effectively utilized because of its large resource amount. For example, lignin-modified phenolic resins in which a part of phenolic resins is replaced with plant-derived lignin have been studied. As an example, a resin composition containing a lignin-modified phenolic resin obtained by reacting lignin, phenols, and aldehydes in the presence of an organic acid has been proposed (Patent Document 1).

[0004] Currently, industrially obtained lignin includes, for example, lignin containing sulfur in its structure, which is obtained by the kraft pulping process, the mainstream of the pulp manufacturing method. When such sulfur-containing lignin is used, the resulting lignin-modified phenol resin also contains sulfur. When such a sulfur-containing lignin-modified phenol resin is mixed with other components to form a resin composition, and when this is heated and molded into various molded products, a pungent odor or unpleasant odor derived from the sulfur content of the sulfur-containing lignin-modified phenol resin is generated, which poses a problem of having a great adverse effect on workers. Reducing the lignin modification rate to suppress the generation of odor is not preferable because it leads to a decrease in the biomass content.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a resin composition containing a lignin-modified phenol resin in which the generation of odor is suppressed while containing a high ratio of biomass materials.

Means for Solving the Problems

[0007] According to the present invention, there are provided the following resin composition and a method for suppressing the odor of a resin material. [1] A resin composition comprising a sulfur-containing lignin-modified novolac-type phenol resin, a volatile sulfur compound, and a sulfur-based gas scavenger, wherein the sulfur-containing lignin-modified novolac-type phenol resin is a resin composition that is a reaction product of sulfur-containing lignin, phenols, and aldehydes. [2] The resin composition according to item [1], wherein the sulfur-containing lignin-modified novolak-type phenol resin has a weight-average molecular weight exceeding 3500. [3] The resin composition according to item [1] or [2], wherein the sulfur-containing lignin-modified novolak-type phenol resin is a reaction product obtained by mixing the sulfur-containing lignin, the phenols, and the aldehydes and heating them at a temperature of 100 °C or higher. [4] The resin composition according to item [1] or [2], wherein the sulfur-containing lignin-modified novolak-type phenol resin is a reaction product obtained by a step of reacting the phenols and the aldehydes to obtain a phenol resin, and a step of mixing the phenol resin and the sulfur-containing lignin and heating them at a temperature of 100 °C or higher. [5] The resin composition according to any one of items [1] to [4], wherein the pH of the resin composition is 2 or more and 9 or less. [6] The resin composition according to any one of [1] to [5], wherein the sulfur-based gas scavenger contains at least one selected from ammonia, amines, alkali metal salts, alkaline earth metal salts, first transition element salts, zinc salts, and aluminum salts. [7] The resin composition according to item [6], wherein the amines have a boiling point of 80 °C or higher. [8] The resin composition according to any one of items [1] to [7], wherein the concentration of the sulfur-based gas generated when the resin composition is heated at 60 °C is 2 ppm or less. [9] The resin composition according to item [8], wherein the sulfur-based gas contains at least one selected from hydrogen sulfide and alkyl mercaptans.

[10] The resin composition according to any one of items [1] to [9], further containing a fragrance.

[11] The resin composition according to item

[10] , wherein the fragrance contains at least one selected from ethers, ketones, esters, aldehydes, and alcohols.

[12] The resin composition according to any one of items [1] to

[11] , A resin composition in which the content of free phenols in the resin composition is less than 2% by mass.

[13] A method for suppressing the odor of a resin material containing a sulfur-containing lignin-modified novolac-type phenol resin and a volatile sulfur compound, A step of reacting a sulfur-containing lignin, phenols, and aldehydes to obtain a resin material containing a sulfur-containing lignin-modified novolac-type phenol resin and a volatile sulfur compound, A method including a step of adding a sulfur-based gas scavenger to the resin material containing a sulfur-containing lignin-modified novolac-type phenol resin and a volatile sulfur compound to capture the volatile sulfur compound.

[14] The method according to item

[13] , A method including a step of adding a fragrance to the resin material before, after, or during the step of adding a sulfur-based gas scavenger to the resin material containing a sulfur-containing lignin-modified novolac-type phenol resin and a volatile sulfur compound to capture the volatile sulfur compound.

[15] The step of reacting a sulfur-containing lignin, phenols, and aldehydes to obtain a resin material containing a sulfur-containing lignin-modified novolac-type phenol resin and a volatile sulfur compound includes a step of mixing the sulfur-containing lignin, the phenols, and the aldehydes and heating at a temperature of 100 °C or higher, according to the method described in item

[13] or

[14] .

[16] The step of reacting a sulfur-containing lignin, phenols, and aldehydes to obtain a resin material containing a sulfur-containing lignin-modified novolac-type phenol resin and a volatile sulfur compound is A step of reacting the phenols and the aldehydes to obtain a phenol resin, A step of mixing the phenol resin and the sulfur-containing lignin and heating at a temperature of 100 °C or higher, according to the method described in

[13] or

[14] . [Advantages of the Invention]

[0008] According to the present invention, there is provided a resin composition containing a lignin-modified phenol resin in which the generation of odor is suppressed while containing a biomass material at a high ratio. [Embodiments for Carrying Out the Invention]

[0009] Hereinafter, embodiments of the present invention will be described. In this specification, the notation "a to b" in the description of a numerical range means "a or more and b or less" unless otherwise specified. For example, "5 to 90%" means "5% or more and 90% or less".

[0010] [Resin Composition] The resin composition of the present embodiment contains a sulfur-containing lignin-modified novolak-type phenol resin, a volatile sulfur compound, and a sulfur-based gas scavenger. In the resin composition of the present embodiment, the sulfur-containing lignin-modified novolak-type phenol resin is a reaction product of at least sulfur-containing lignin, phenols, and aldehydes.

[0011] The resin composition of the present embodiment contains a sulfur-containing lignin-modified novolak-type phenol resin, which is a reaction product of sulfur-containing lignin, phenols, and aldehydes. Kraft lignin, which is sulfur-containing lignin, is a lignin compound obtained by subjecting plants such as wood to kraft pulping treatment using a chemical agent containing sulfur such as sodium sulfide, and thus contains sulfur in its structure. Further, the sulfur-containing lignin-modified novolak-type phenol resin, which is a reaction product of such sulfur-containing lignin, phenols, and aldehydes, contains sulfur atoms derived from sulfur-containing lignin in its structure. Further, the above reaction product unavoidably contains a volatile sulfur compound as a by-product. By containing a sulfur-based gas scavenger, the resin composition of the present embodiment reduces the odor caused by the volatile sulfur compound, and thus has good handleability. Hereinafter, each component used in the resin composition of the present embodiment will be described in detail.

[0012] (Sulfur-Containing Lignin-Modified Novolak-Type Phenol Resin) The sulfur-containing lignin-modified novolak-type phenol resin used in the resin composition of this embodiment is a product obtained by reacting sulfur-containing lignin, phenols, and aldehydes in the presence of an acid catalyst. Hereinafter, the materials and production conditions used for the production of the sulfur-containing lignin-modified novolak-type phenol resin will be described.

[0013] - Sulfur-containing lignin Sulfur-containing lignin is a lignin compound containing sulfur atoms in its structure, which is obtained by extracting lignin-containing materials such as plants containing natural lignin with a chemical solution containing sulfur. Representative examples of sulfur-containing lignin include kraft lignin obtained from tree-based (lignocellulosic) plants. Kraft lignin is obtained by subjecting tree-based plants containing natural lignin to high-temperature and high-pressure treatment (kraft pulping) using an alkaline aqueous solution such as sodium hydroxide and sodium sulfide, and liberating, converting, and extracting the molecular chains of natural lignin by alkaline treatment using a sodium sulfide-containing alkaline aqueous solution. Kraft lignin can be taken out, for example, by operations such as separating the black liquor from which pulp has been separated, carbonating it, or acidifying it to cause precipitation.

[0014] When producing kraft lignin from wood chips, the wood chips are charged into a digester together with the cooking liquor, and kraft pulping is performed. This kraft pulping is carried out by immersing the wood chips, which are lignin-containing materials, in an alkaline aqueous solution containing sodium sulfide and performing an alkaline treatment at a temperature of 120 to 170°C for 60 to 360 minutes in a closed system. As the raw material wood, for example, hardwood, softwood, miscellaneous wood, bamboo, kenaf, bagasse, and the empty shell after palm oil pressing can be used.

[0015] In kraft pulping, in addition to the liberation of the molecular chains of natural lignin, self-condensation occurs between the primary molecular chains of the decomposed natural lignin to form carbon-carbon bonds (C-C bonds), and sulfur-based bonds (such as sulfide bonds and disulfide bonds) based on sodium sulfide are formed.

[0016] Lignin compounds (lignin extracted from lignin-containing materials) are usually obtained as mixtures of various components depending on conditions such as raw materials, various conditions of manufacturing methods, extraction methods, etc. It is important that lignin compounds, such as kraft lignin, contain sulfur-based bonds in their molecules depending on their manufacturing methods. The molecular weight of kraft lignin is not particularly limited, but as an example of the molecular weight, a range of about 1,000 to 100,000 can be mentioned.

[0017] - Phenols Examples of phenols used in the production of sulfur-containing lignin-modified novolak-type phenolic resins include phenol, phenol derivatives, and combinations thereof. As the phenol derivative, phenol with an arbitrary substituent introduced into the benzene ring can be used. Examples of the substituent include a hydroxy group; lower alkyl groups such as a methyl group and an ethyl group; halogen atoms such as fluorine, chlorine, bromine, and iodine; an amino group; a nitro group; a carboxy group, etc. Specific examples of phenols that can be used include phenol, catechol, resorcinol, hydroquinone, o-cresol, m-cresol, p-cresol, o-fluorophenol, m-fluorophenol, p-fluorophenol, o-chlorophenol, m-chlorophenol, p-chlorophenol, o-bromophenol, m-bromophenol, p-bromophenol, o-iodophenol, m-iodophenol, p-iodophenol, o-aminophenol, m-aminophenol, p-aminophenol, o-nitrophenol, m-nitrophenol, p-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol, salicylic acid, p-hydroxybenzoic acid, and combinations thereof.

[0018] As phenols, alkylphenols having 2 to 18 carbon atoms can also be used. The alkylphenols may have a branched chain in the alkyl chain or an unsaturated bond. Also, the substitution position of the alkyl chain on the benzene ring may be any of ortho, meta, and para substitutions. Examples of alkylphenols include, for example, ethylphenol, propylphenol, isopropylphenol, butylphenol, secondary butylphenol, tertiary butylphenol, amylphenol, tertiary aminophenol, hexylphenol, heptylphenol, octylphenol, tertiary octylphenol, nonylphenol, tertiary nonylphenol, decylphenol, undecylphenol, dodecylphenol, tridecylphenol, tetradecylphenol, pentadecylphenol, cardanol, cardol, urushiol, hexadecylphenol, methyl cardol, heptadecylphenol, laccol, thiol, octadecylphenol. Also, as alkylphenols, vegetable oils such as cashew nut shell liquid (cashew oil) and urushi extract can be used. The phenols may be used alone or in combination of two or more.

[0019] Among these, as phenols, phenol, cresol, xylenol, alkylphenol, or bisphenol is preferable, and from the viewpoint of production cost, it is preferable to use phenol, cresol, butylphenol, or bisphenol A.

[0020] - Aldehydes Examples of aldehydes used in the production of sulfur-containing lignin-modified novolak-type phenolic resins include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n-butylaldehyde, caproaldehyde, allyl aldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde, para-xylene dimethyl ether, and the like. Preferably, formaldehyde, paraformaldehyde, trioxane, polyoxymethylene, acetaldehyde, para-xylene dimethyl ether, and combinations thereof are mentioned. Aldehydes may be used alone or in combination of two or more. Among these, from the viewpoints of productivity and low cost, it is preferable to use formaldehyde or acetaldehyde.

[0021] - Acid catalyst Examples of acid catalysts used in the production of sulfur-containing lignin-modified novolak-type phenolic resins may be any that can be used as a catalyst for the reaction, and organic acids, inorganic acids, and combinations thereof can be used. Examples of organic acids include acetic acid, formic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, benzoic acid, salicylic acid, sulfonic acid, phenolsulfonic acid, p-toluenesulfonic acid, and the like. Examples of inorganic acids include hydrochloric acid, sulfuric acid, sulfuric acid esters, phosphoric acid, phosphoric acid esters, and the like.

[0022] - Method for producing sulfur-containing lignin-modified novolak-type phenolic resin In this embodiment, the sulfur-containing lignin-modified novolak-type phenol resin is mainly a reaction product of kraft lignin, phenols, and aldehydes. Examples of the method for reacting lignins, phenols, and aldehydes include a method (method a) in which kraft lignin, phenols, aldehydes, and an acid catalyst are charged and reacted together, or a method (method b) in which phenols and aldehydes are reacted in the presence of an acid catalyst to obtain a novolak-type phenol resin, and then kraft lignin is added thereto and reacted.

[0023] In the reaction of kraft lignin, phenols, and aldehydes for producing a sulfur-containing lignin-modified novolak-type phenol resin, the molar ratio (F / P) of aldehydes to phenols is, for example, 0.5 or more, preferably 0.55 or more, and more preferably 0.6 or more. The upper limit value of the molar ratio (F / P) of aldehydes to phenols is, for example, 1.2 or less, preferably 1.1 or less, and more preferably 1.0 or less. By carrying out the reaction under the condition that the molar ratio (F / P) of aldehydes to phenols is within the above range, a sulfur-containing lignin-modified novolak-type phenol resin having a target weight-average molecular weight and improved both in processability and strength can be obtained.

[0024] When producing a sulfur-containing lignin-modified novolak-type phenol resin using the above (Method a), the step of reacting kraft lignin, phenols, and aldehydes in the presence of an acid catalyst is carried out, for example, at a temperature of 90°C or higher, preferably at a temperature of 100 to 120°C, and for a reaction time of, for example, 10 minutes to 100 minutes. Thereby, the reaction can proceed efficiently and sufficiently. The reaction time is not particularly limited and may be appropriately determined according to the type of starting materials, the compounding molar ratio, the amount and type of catalyst used, and the reaction conditions. The reaction mixture containing the sulfur-containing lignin-modified novolak-type phenol resin obtained by the above reaction contains volatile sulfur compounds generated from kraft lignin or volatile sulfur compounds derived from sulfur remaining in kraft lignin. Further, the reaction mixture containing the sulfur-containing lignin-modified novolak-type phenol resin obtained by the above reaction may contain a novolak-type phenol resin, a reaction product of kraft lignin, unreacted kraft lignin, free phenols, and free aldehydes.

[0025] When producing a sulfur-containing lignin-modified novolak-type phenol resin using the above (Method b), the step of reacting phenols and aldehydes in the presence of an acid catalyst to obtain a novolak-type phenol resin is carried out by reacting a reaction mixture of phenols, aldehydes, and an acid catalyst, for example, at a temperature of 90°C or higher, preferably at a temperature of 100 to 120°C, and for a reaction time of, for example, 10 minutes to 100 minutes. The reaction time is not particularly limited and may be appropriately determined according to the type of starting materials, the compounding molar ratio, the amount and type of catalyst used, and the reaction conditions.

[0026] Next, kraft lignin is added to a reaction mixture containing a novolak-type phenol resin, and the novolak-type phenol resin and kraft lignin are mixed in a molten state by heating, for example, at a temperature of 100°C or higher, preferably at a temperature of 100 to 180°C, to obtain a sulfur-containing lignin-modified novolak-type phenol resin. This step is carried out, for example, at a temperature of 100°C or higher and with a reaction time of, for example, 10 minutes to 100 minutes. The sulfur-containing lignin-modified novolak-type phenol resin obtained by the above step contains volatile sulfur compounds generated from kraft lignin or volatile sulfur compounds derived from sulfur residues in kraft lignin. Further, the reaction mixture containing the sulfur-containing lignin-modified novolak-type phenol resin obtained by the above step may contain a novolak-type phenol resin, a reaction product of the novolak-type phenol resin and kraft lignin, a reaction product of kraft lignin, unreacted kraft lignin, free phenols, and free aldehydes.

[0027] In any of the above cases of (Method a) and (Method b), the obtained reaction mixture containing the sulfur-containing lignin-modified novolak-type phenol resin can be used as a resin material for producing a resin composition without further treatment. Alternatively, the obtained reaction mixture containing the sulfur-containing lignin-modified novolak-type phenol resin may be subjected to distillation treatment or water washing treatment to reduce or remove the amount of unreacted free phenol contained therein.

[0028] In one embodiment, the sulfur-containing lignin-modified novolak-type phenol resin preferably has a weight average molecular weight exceeding 3,500. The weight average molecular weight of the sulfur-containing lignin-modified novolak-type phenol resin is preferably 4,000 or more, more preferably 4,500 or more, and even more preferably 5,000 or more. The sulfur-containing lignin-modified novolak-type phenol resin used in the resin composition of this embodiment has a high weight average molecular weight, so that its cured product has high mechanical strength.

[0029] Here, an example of a method for measuring the above-mentioned molecular weight will be described. In a method for measuring molecular weight by gel permeation chromatography, first, a lignin derivative and a lignin-modified phenolic resin are dissolved in a solvent to prepare a measurement sample. The solvent used at this time is not particularly limited as long as it can dissolve the lignin derivative, but from the viewpoint of the measurement accuracy of gel permeation chromatography, for example, tetrahydrofuran and N-methyl-2-pyrrolidone are preferable. Since the lignins of the present embodiment may contain insoluble components due to biomass, process-derived inorganic substances, and plant-derived high molecular weight organic substances, the molecular weight of the lignins is obtained by selecting an appropriate solvent and filtering the insoluble components. Further, in order to increase the lignin modification rate of the obtained lignin-modified novolak-type phenolic resin, the insoluble content of the lignins used is preferably 30% by mass or less under an appropriate solvent. The molecular weight of the lignin-modified novolak-type phenolic resin is similarly obtained by filtering the insoluble components. The insoluble content in the lignin-modified novolak-type phenolic resin is preferably 15% by mass or less, and more preferably 10% by mass or less. If the content is within the above range, the lignin-modified novolak-type phenolic resin has good curability and can be cured uniformly in particular.

[0030] Next, an organic general-purpose column "TSKgel GMHXL (manufactured by Tosoh)" and "G2000HXL (manufactured by Tosoh)", which are styrene-based polymer-packed columns, are connected in series to a GPC system "HLC-8320GPC (manufactured by Tosoh)". 200 μL of the above-described measurement sample is injected into this GPC system, and at 40°C, the eluent tetrahydrofuran is developed at 1.0 mL / min, and the retention time is measured using differential refractive index (RI) and ultraviolet absorbance (UV). The number average molecular weight and weight average molecular weight of the target lignins can be calculated from a calibration curve showing the relationship between the retention time and molecular weight of the standard polystyrene prepared separately. The refractive index is preferable as the detection mode.

[0031] The molecular weight of the standard polystyrene used to create the calibration curve is not particularly limited. For example, standard polystyrene (manufactured by Tosoh Corporation) with weight average molecular weights of 1,090,000, 427,000, 190,000, 96,400, 37,900, 18,100, 10,200, 5,970, 2,630, 1,050, and 500 can be used.

[0032] In one embodiment, the sulfur-containing lignin-modified novolak-type phenol resin has a lignin modification rate of 25% or more and 60% or less. By including the sulfur-containing lignin-modified novolak-type phenol resin having a lignin modification rate within the above range, the resin composition of this embodiment has excellent resin strength and is excellent in curability and moldability.

[0033] Note that the above-mentioned lignin modification rate was calculated by the following formula on the assumption that the amount of lignin non-volatile matter did not change before and after modification when using lignin non-volatile matter. Amount of lignin non-volatile matter = Amount of raw lignin × Weight residual rate of raw lignin when dried at 135°C for 1 hour Lignin modification rate (%) = (Amount of charged lignin non-volatile matter) / (Yield of phenol-modified lignin resin) × 100

[0034] (Volatile sulfur compound) The resin composition of this embodiment contains a volatile sulfur compound together with the sulfur-containing lignin-modified novolak-type phenol resin. The volatile sulfur compound is a substance generated in the production of the above-mentioned sulfur-containing lignin-modified novolak-type phenol resin.

[0035] Examples of the volatile sulfur compound include hydrogen sulfide, sulfur oxides such as SO X etc., and alkyl mercaptans such as methyl mercaptan, but are not limited thereto.

[0036] (Sulfur-based gas scavenger) The resin composition of this embodiment contains a sulfur-based gas scavenger. The sulfur-based gas scavenger captures sulfur-based gases, which are gasified products of the above-mentioned volatile sulfur compounds, and functions to reduce the odor derived from sulfur-based gases, and is particularly effective for sulfur oxides having a pungent odor. Here, reducing the odor of sulfur-based gases by the sulfur-based gas scavenger includes neutralizing sulfur-based gases with the sulfur-based gas scavenger to reduce the odor, or capturing sulfur-based gases with the sulfur-based gas scavenger to reduce the odor.

[0037] Examples of the sulfur-based gas scavenger include ammonia, amines, alkali metal salts, alkaline earth metal salts, first transition element salts, zinc salts, and aluminum salts. In particular, from the viewpoint of handleability, it is preferable to use an organic base having a boiling point of 80°C or higher, preferably 80°C or higher and 150°C or lower as the sulfur-based gas scavenger. Examples of such sulfur-based gas scavengers include amines such as ammonia, alkylamines, alkanolamines, and cyclic amines. Examples of alkylamines include primary alkylamines having an alkyl group with 1 to 6 carbon atoms, and secondary or tertiary alkylamines having an alkyl group with 1 to 4 carbon atoms. The alkyl groups in the secondary or tertiary alkylamines may have different carbon numbers. Specifically, there are methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, isobutylamine, tertiary butylamine, pentylamine, neopentylamine, hexylamine, cyclohexylamine, methylethylamine, methyldiethylamine, triethylenetetramine, etc. Examples of alkanolamines include alkanolamines such as mono-, di- or triethanolamine, and β-aminoalcohols such as 2-amino-2-methyl-1-propanol. Examples of cyclic amines include morpholine and piperidine. These sulfur-based gas scavengers may be used alone or in combination of two or more.

[0038] The blending amount of the sulfur-based gas scavenger can be appropriately adjusted depending on the amount of the volatile sulfur compound contained in the sulfur-containing lignin-modified novolak-type phenol resin. The blending amount of the sulfur-based gas scavenger is, for example, 0.001 to 3% by mass, preferably 0.01 to 2% by mass, more preferably 0.05 to 1% by mass, based on the mass of the sulfur-containing lignin-modified novolak-type phenol resin. By using the sulfur-based gas scavenger in the amount within the above range, the odor of the sulfur-based gas can be suppressed without affecting the performance of the resulting resin composition and its cured product.

[0039] (Fragrance) The resin composition of the present embodiment may contain a fragrance. Here, the fragrance refers to a component that has an aroma and acts to mask the sulfur-based gas and relieve or reduce or deodorize the odor of the sulfur-based gas. The fragrance is not limited in type as long as it has an effect of masking the odor caused by the sulfur-based compound, and examples thereof include ethers, ketones, esters, aldehydes, and alcohols. Examples of ethers include cineole, examples of ketones include menthone and 2-boronanone, examples of esters include ethyl isobutyrate, examples of aldehyde-based fragrances include perillyl aldehyde and vanillin, and examples of alcohols include menthol. These fragrances may be used alone or in combination of two or more.

[0040] When using a fragrance, its blending amount can be appropriately adjusted depending on the amount of the volatile sulfur compound contained in the sulfur-containing lignin-modified novolak-type phenol resin. The blending amount of the fragrance is, for example, 0.001 to 2% by mass, preferably 0.005 to 1% by mass, more preferably 0.01 to 0.5% by mass, based on the mass of the sulfur-containing lignin-modified novolak-type phenol resin. Also, when using a fragrance, a synergistic effect with the above sulfur-based gas scavenger may occur, and the amounts of both can be suppressed. By using the fragrance in the amount within the above range, the odor of the sulfur-based gas can be effectively suppressed without affecting the performance of the resulting resin composition and its cured product.

[0041] (Other components) Depending on the application, the resin composition of this embodiment can contain other components in addition to the components described above. Examples of such other components include fillers such as fiber substrates, organic fillers, and inorganic fillers; elastomers such as acrylonitrile-butadiene rubber, isoprene, styrene-butadiene rubber, and ethylene-propylene rubber; curing accelerators such as oxides or hydroxides of alkaline earth metals; resin components such as bismaleimide resin, polyurethane resin, silicone resin, resin having a benzoxazine ring, cyanate ester resin, polyvinyl butyral resin, and polyvinyl acetate resin; release agents such as stearic acid, calcium stearate, zinc stearate, and polyethylene; pigments such as carbon black; flame retardants; adhesion improvers; coupling agents, and the like.

[0042] (Method for producing the resin composition) The resin composition of this embodiment is obtained by melting and adding a sulfur-containing lignin-modified novolac type phenol resin containing a volatile sulfur-based compound, a sulfur-based gas scavenger, and other components used as required in a reaction kettle for shaping, or by previously melt-kneading with a kneader, roll, etc., then uniformly mixing with the above other components, or by melt-kneading all the raw material components to be blended with a kneading device such as a roll, a conical kneader, or a twin-screw extruder alone or in combination with a roll and other mixing devices, and then granulating or pulverizing. In this embodiment, the resin composition is provided in a form such as flake, pellet, powder granule, granule, tablet, or sheet.

[0043] The resin composition of this embodiment can control the pH in the range of 2 to 9, preferably in the range of 3 to 9, more preferably in the range of 4 to 9, by adjusting the blending amounts of the above components.

[0044] The resin composition of this embodiment has a free phenols content of less than 2% by mass, preferably less than 1.5% by mass, and more preferably less than 1% by mass, based on the total resin composition. The free phenols are unreacted phenols from the raw materials used in the production of the above-mentioned sulfur-containing lignin-modified novolac phenol resin. Since the resin composition of this embodiment has a reduced free phenols content, the generation of off-odors derived from free phenols is suppressed, and it has excellent handleability.

[0045] By including the above components, the resin composition of this embodiment has a reduced concentration of sulfur-based gases generated when the resin composition is heated at 60°C to 2 ppm or less. Here, the sulfur-based gas is hydrogen sulfide, an alkyl mercaptan, or a sulfur oxide. In the resin composition of this embodiment, the sulfur-based gas is neutralized / captured by a sulfur-based gas scavenger, so the unpleasant odor caused by hydrogen sulfide is reduced. Also, in the resin composition of this embodiment, the pungent odor caused by sulfur dioxide is reduced by a sulfur-based gas scavenger.

[0046] [Odor Suppression Method] In this embodiment, the present invention relates to a method for suppressing the odor of a resin material containing a sulfur-containing lignin-modified novolac phenol resin and a volatile sulfur compound, and the method includes: a step (Step 1) of reacting a sulfur-containing kraft lignin, phenols, and aldehydes to obtain a resin material containing a sulfur-containing lignin-modified novolac phenol resin and a volatile sulfur compound; a step (Step 2) of adding a sulfur-based gas scavenger to the resin material containing the sulfur-containing lignin-modified novolac phenol resin and the volatile sulfur compound to capture the volatile sulfur compound.

[0047] The sulfur-containing lignin-modified novolac phenol resin and the sulfur-based scavenger used in the method of this embodiment are the same as those described above. In one embodiment, the odor suppression method of the present invention uses a reaction product containing a sulfur-containing lignin-modified novolak-type phenol resin and a volatile sulfur compound obtained by the above-mentioned (Method a) as a resin material, and adds a sulfur-based gas scavenger to the resin material to suppress the odor derived from the sulfur-based gas.

[0048] In one embodiment, the odor suppression method of the present invention uses a reaction product containing a sulfur-containing lignin-modified novolak-type phenol resin and a volatile sulfur compound obtained by the above-mentioned (Method b) as a resin material, and adds a sulfur-based gas scavenger to the resin material to suppress the odor derived from the sulfur-based gas.

[0049] In one embodiment, when performing the above-mentioned (Step 2), in addition to the sulfur-based gas scavenger, a fragrance may be added. The timing of adding the fragrance may be before adding the sulfur-based gas scavenger, may be simultaneous with adding the sulfur-based gas scavenger, or may be after adding the sulfur-based gas scavenger. The fragrance to be used is the same as those described above.

[0050] As described above, the embodiments of the present invention have been described, but these are examples of the present invention, and various configurations other than the above can also be adopted.

Examples

[0051] Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0052] [Preparation of Sulfur-Containing Lignin-Modified Novolak-Type Phenol Resin] (Preparation Example 1: Sulfur-Containing Lignin-Modified Novolak-Type Phenol Resin 1) (Preparation of Kraft Lignin 1) First, Kraft lignin 1 used for the synthesis of the sulfur-containing lignin-modified novolak-type phenol resin was prepared by the following procedure. 1500 parts by weight of Japanese cedar wood powder with a moisture content of 50% was charged into a 10 L stainless steel autoclave equipment together with 5000 parts by weight of pure water, 150 parts by weight of sodium hydroxide, 80 parts by weight of sodium sulfide, 70 parts by mass of sodium carbonate as a cooking liquor, and 7.5 parts by weight of 9,10-anthraquinone as a cooking aid. A cooking reaction was carried out at 170 °C for 3 hours under stirring. After the cooking liquor after the reaction was cooled to room temperature and the pulp component was removed by a screen, the black liquor containing lignin was separated. Dilute sulfuric acid was added to the separated black liquor to adjust the pH to 8, and the resulting precipitate was centrifuged. After washing twice with 500 parts by mass of water, the precipitate was suspended in 5 times the amount of water and readjusted to pH 2 with dilute sulfuric acid. The precipitated lignin was centrifuged again, washed repeatedly by adding water again, then suction filtered, spread on a tray and air-dried, and dried in a vacuum oven at 80 °C or lower to obtain 140 to 150 parts by weight (in terms of solid content) of kraft lignin in the form of a brown powder with a solid content of 70% or more. A part of the obtained hydrated lignin was further dried in a vacuum oven at 80 °C or lower to obtain alkali lignin with a solid content of 99% by mass. The solid content ratio was calculated from the residual ratio after heating and drying 4 g of the sample in an aluminum cup at 135 °C for 1 hour. The number average molecular weight (Mn) of the obtained lignin derivative (kraft lignin 1) was 2,000, and the weight average molecular weight (Mw) was 14,000.

[0053] (Preparation of Sulfur-Containing Lignin-Modified Novolak-Type Phenol Resin 1) Subsequently, sulfur-containing lignin-modified novolak-type phenol resin 1 was synthesized by the following procedure. 100 parts by weight of phenol was added to a four-necked flask equipped with a stirrer, a cooling tube and a thermometer, and 33.0 parts by weight (non-volatile content) of the kraft lignin 1 obtained above was gradually added. Then, 1.5 parts by weight of oxalic acid was added, and the mixture was mixed and dispersed at 70 °C or higher. Subsequently, 49.2 parts by weight of a 37% aqueous formaldehyde solution was gradually added over 60 minutes and reacted at 100 °C. After the addition, the reaction was carried out at 100 °C for 60 minutes. Then, the temperature was raised to 150 °C or higher by dehydration under normal pressure and reduced pressure until the phenol concentration was less than 5%, and then taken out to obtain 118.1 parts by weight of lignin-modified novolac-type phenol resin 1. The lignin modification rate was 28%, the number average molecular weight (Mn) was 700, and the weight average molecular weight (Mw) was 7,000.

[0054] (Preparation Example 2: Sulfur-containing lignin-modified novolac-type phenol resin 2) (Preparation of kraft lignin 2) First, kraft lignin 2 used for the synthesis of sulfur-containing lignin-modified novolac-type phenol resin was prepared by the following procedure. 150 parts by weight (in terms of solid content) of brown powdery kraft lignin 1 with a solid content of 70% or more obtained by the same method as the preparation of kraft lignin 1 was immersed in 500 parts of acetone for 12 hours. This was filtered, and acetone was distilled off from the filtrate at 70 °C or lower and dried to obtain 60 to 70 parts by weight of a lignin derivative. The number average molecular weight (Mn) of the obtained lignin derivative (kraft lignin 2) was 810, and the weight average molecular weight (Mw) was 2,070.

[0055] (Preparation of sulfur-containing lignin-modified novolac-type phenol resin 2) Subsequently, sulfur-containing lignin-modified novolac-type phenol resin 2 was synthesized by the following procedure. 100 parts by weight of phenol was added to a four-necked flask equipped with a stirrer, a cooling tube and a thermometer, and while stirring, 33.3 parts by weight (non-volatile content) of solvent-extracted kraft lignin 2 was gradually added, 1.5 parts by weight of oxalic acid was added, and 56.1 parts by weight of a 37% aqueous formaldehyde solution was gradually added over 60 minutes and reacted at 100 °C. After the addition, the reaction was carried out at 100 °C for 60 minutes, and the temperature was raised to 150 °C or higher by dehydration under normal pressure and reduced pressure. When the phenol concentration reached 1% or less, it was taken out, and 116.2 parts by weight of sulfur-containing lignin-modified novolak-type phenol resin 2 was obtained. The lignin modification rate was 29%, the number average molecular weight (Mn) was 650, and the weight average molecular weight (Mw) was 2,500.

[0056] (Preparation Example 3: Preparation of sulfur-containing lignin-modified novolak-type phenol resin 3) Using the same kraft lignin 1 as in Preparation Example 1, sulfur-containing lignin-modified novolak-type phenol resin 3 was synthesized by the following procedure. The same operation as in Preparation Example 1 was carried out except that 90 parts by weight of phenol and 10 parts by weight of cashew shell oil were used instead of 100 parts by weight of phenol, and 120.3 parts by weight of lignin-modified novolak-type phenol resin 3 was obtained. The lignin modification rate was 28%, the number average molecular weight (Mn) was 720, and the weight average molecular weight (Mw) was 7,800.

[0057] [Examples 1 to 10, Comparative Examples 1 to 2] (Preparation of resin composition) In a 3 L four-necked flask, the components shown in Table 1 below were mixed according to the compounding ratios shown in Table 1 with lignin-modified phenol resins 1, 2, and 3 melted at 150 °C or higher to prepare a resin composition. Details of the components in Table 1 are as follows. (Lignin-modified novolak-type phenol resin) · Lignin-modified phenol resin 1: Sulfur-containing lignin-modified novolak-type phenol resin 1 obtained in Preparation Example 1 above · Lignin-modified phenol resin 2: Sulfur-containing lignin-modified novolak-type phenol resin 2 obtained in Preparation Example 2 above · Modified lignin phenol resin 3: Sulfur-containing lignin-modified novolak-type phenol resin 3 obtained in Preparation Example 3 above (Sulfur-based gas scavenger) · Scavenger 1: Sodium hydroxide · Scavenger 2: Triethylenetetramine · Scavenger 3: Calcium hydroxide · Scavenger 4: Iron(III) hydroxide · Scavenger 5: Aluminum hydroxide · Scavenger 6: Zinc oxide (Fragrance) · Fragrance 1: Menthone · Fragrance 2: Cineole

[0058] (Measurement of physical properties of resin composition) The obtained resin composition was measured for the following physical properties. (Amount of sulfur dioxide generated) From one of the four mouths of a 3 L four-necked flask containing the resin composition obtained by the above method, the resin composition was taken out, and then the four-necked flask was allowed to stand at room temperature and cooled for 5 minutes. After confirming that the vapor in the four-necked flask had subsided, a Kitagawa-type detector tube (TUBE NO. 103SE manufactured by Komyo Rikagaku Kogyo Co., Ltd.) attached to a Kitagawa-type gas sampler was deeply inserted through one of the mouths to measure the amount of sulfur dioxide inside the flask. The measured values are shown in Table 1. Also, the air around the four-necked flask was measured, but no sulfur dioxide was detected. (Evaluation of pungent odor after removal) The odor when the resin composition was taken out from the four-necked flask was evaluated sensorially. The determination of the strength of the odor was evaluated by three panelists according to the following criteria. (Sensory evaluation criteria for pungent odor) 1: All three panelists clearly felt that the pungent odor was significantly reduced. 2: Among the three panelists, 1 - 2 panelists felt a reduction in the pungent odor. 3: All three panelists felt the pungent odor and could not continue due to the irritation. (pH) The pH of the resin composition was measured using a pH meter (measurement temperature 23°C). The results are shown in Table 1.

[0059] (Physical Property Measurement of the Ground Product of the Resin Composition) The ground product of the obtained resin composition was measured for the following physical properties. (Amount of Hydrogen Sulfide Generated) 2 g of the resin composition of each example and each comparative example was ground with a small universal grinder to prepare a sample. Next, approximately 1 g of the sample was placed in a 1 L Tedlar bag, 1000 ml of air was added to 1 g of the sample, and the bag was sealed and heated in an oven at 60 °C for 1 h. The taken-out Tedlar bag was cooled to room temperature, and the amount of hydrogen sulfide generated was measured using a Kitagawa-type detector tube (Kitagawa-type detector tube TUBE NO. 120U manufactured by Komyo Rikagaku Kogyo Co., Ltd.) attached to a Kitagawa-type gas sampler. The results are shown in Table 1. Also, air was measured, but hydrogen sulfide was not detected. Although the Kitagawa-type detector tube (Kitagawa-type detector tube TUBE NO. 120U manufactured by Komyo Rikagaku Kogyo Co., Ltd.) is intended for the measurement of hydrogen sulfide, it also reacts with alkyl mercaptans.

[0060] (Odor of the Ground Product) 2 g of the resin composition of each example and each comparative example was ground with a small universal grinder to prepare a sample. 0.1 g of the sample was weighed, sealed in a 500 ml glass container, held at 50 °C for 10 minutes, then the lid of the glass container was opened, and the internal odor was evaluated sensorially. The determination of the odor intensity was evaluated by three panelists according to the following criteria. (Sensory Evaluation Criteria for Unpleasant Odors) 1: None of the three panelists could hardly feel the smell of rotten eggs, and they felt that the unpleasant odor was clearly reduced. 2: All three panelists could feel the smell of rotten eggs and felt that there was an unpleasant odor. 3: All three panelists could feel the smell of rotten eggs and felt that the unpleasant odor was very strong.

[0061]

Table 1

Claims

1. A resin composition comprising a sulfur-containing lignin-modified novolac-type phenol resin, a volatile sulfur compound, and a sulfur-based gas scavenger, wherein the sulfur-containing lignin-modified novolac-type phenol resin is a reaction product of sulfur-containing lignin, phenols, and aldehydes.

2. The resin composition according to claim 1, wherein the sulfur-containing lignin-modified novolac-type phenol resin has a weight average molecular weight exceeding 3500.

3. The resin composition according to claim 1, wherein the sulfur-containing lignin-modified novolac-type phenol resin is a reaction product obtained by mixing the sulfur-containing lignin, the phenols, and the aldehydes and heating at a temperature of 100°C or higher.

4. The resin composition according to claim 1, wherein the sulfur-containing lignin-modified novolac-type phenol resin is a reaction product obtained by a step of reacting the phenols and the aldehydes to obtain a phenol resin, and a step of mixing the phenol resin and the sulfur-containing lignin and heating at a temperature of 100°C or higher.

5. The resin composition according to claim 1, wherein the pH of the resin composition is 2 or more and 9 or less.

6. The resin composition according to claim 1, wherein the sulfur-based gas scavenger contains at least one selected from ammonia, amines, alkali metal salts, alkaline earth metal salts, first transition element salts, zinc salts, and aluminum salts.

7. The resin composition according to claim 6, wherein the amines have a boiling point of 80°C or higher.

8. The resin composition according to claim 1, wherein the concentration of the sulfur-based gas generated when the resin composition is heated at 60°C is 2 ppm or less.

9. The resin composition according to claim 8, wherein the sulfur-based gas contains at least one selected from hydrogen sulfide and alkyl mercaptans.

10. The resin composition according to claim 1, further comprising a fragrance.

11. The resin composition according to claim 10, wherein the fragrance contains at least one selected from ethers, ketones, esters, aldehydes, and alcohols.

12. The resin composition according to claim 1, wherein the content of free phenols in the resin composition is less than 2% by mass.

13. A method for suppressing the odor of a resin material containing a sulfur-containing lignin-modified novolak-type phenol resin and a volatile sulfur compound, a step of reacting a sulfur-containing lignin, phenols, and aldehydes to obtain a resin material containing a sulfur-containing lignin-modified novolak-type phenol resin and a volatile sulfur compound, and a step of adding a sulfur-based gas scavenger to the resin material containing the sulfur-containing lignin-modified novolak-type phenol resin and the volatile sulfur compound to capture the volatile sulfur compound.

14. The method according to claim 13, including a step of adding a fragrance to the resin material before, after, or during the step of adding a sulfur-based gas scavenger to the resin material containing the sulfur-containing lignin-modified novolak-type phenol resin and the volatile sulfur compound to capture the volatile sulfur compound.

15. The step of reacting a sulfur-containing lignin, phenols, and aldehydes to obtain a resin material containing a sulfur-containing lignin-modified novolak-type phenol resin and a volatile sulfur compound includes a step of mixing the kraft lignin, the phenols, and the aldehydes and heating at a temperature of 100°C or higher. The method according to claim 13.

16. The step of reacting a sulfur-containing lignin, phenols, and aldehydes to obtain a resin material containing a sulfur-containing lignin-modified novolak-type phenol resin and a volatile sulfur compound includes a step of reacting the phenols and the aldehydes to obtain a phenol resin, and a step of mixing the phenol resin and the sulfur-containing lignin and heating at a temperature of 100°C or higher. The method according to claim 13.

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