JP2012131719A - Method of producing lignin derivative, cured product, and lignin epoxy resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a lignin derivative in which curing reaction is not inhibited even if acid residue occurs.SOLUTION: The method includes: a step of suspending a woody material 1 containing lignin or lignocellulose in an aqueous solution of metallic compounds 2 such as aluminum sulfate; a step of adding as needed a second organic solvents 6 that promotes decomposition, such as ethanol, to the suspension; a step of decomposing the suspension in an autoclave under high-temperature high-pressure condition; a step of adding a first organic solvent 4 such as methyl ethyl ketone to the reaction liquid subjected to the decomposition processing, and thereafter separating the reaction liquid into an organic phase and a water phase; and a step of collecting the organic phase for drying. The lignin derivative 5 is produced which does not inhibit the curing reaction of an epoxy resin 7 even if the acid residue occurs.

Description

  Embodiments of the present invention relate to a method for producing a lignin derivative added to a thermosetting resin, a cured product to which the lignin derivative is added, and a lignin epoxy resin having an epoxy group added to the lignin derivative.

  Conventionally, phenol novolac, bisphenol, and the like are widely used as raw materials for thermosetting resins typified by epoxy resins for the purpose of electrical insulation. However, thermosetting resins are highly dependent on petroleum resources, and insulation materials with new functions are being demanded from harmony with the global environment.

  In response to such demands, in order to industrially use lignin having a phenolic skeleton of wood resources, lignin is solvated with a phenol compound, and an acid such as concentrated sulfuric acid is added to obtain a lignin derivative. (For example, refer to Patent Document 1). An insulating material that suppresses emission of carbon dioxide by dissolving a lignin derivative in an organic solvent such as methyl ethyl ketone together with an epoxy resin such as bisphenol A type epoxy resin and a curing catalyst such as imidazole, and heating it. It is known (for example, refer to Patent Document 2).

Japanese Patent Laid-Open No. 9-278904 JP 2009-29284 A

  The above conventional lignin derivative and the insulating material to which this is added have the following problems. In Patent Document 1, lignin solvated with a phenol compound is separated by contacting with 72% concentrated sulfuric acid to obtain lignophenol which is a kind of lignin derivative. For this reason, sulfuric acid may remain or be mixed in the obtained ligno derivative. In Cited Document 2, when the imidazole that is the curing catalyst is basic and sulfuric acid remains in the lignin derivative, the imidazole that is the curing catalyst is deactivated by the sulfuric acid via methyl ethyl ketone, which is an organic solvent, and the curing reaction is sufficient. It does n’t happen to happen. When insufficient curing occurs, it becomes impossible to obtain various characteristics sufficient as a cured product. The reaction inhibition by acid is the same for the epoxidation reaction.

  The present invention has been made to solve the above problems, and a method for producing a lignin derivative that does not inhibit the curing reaction even if an acid remains, a cured product to which the lignin derivative is added, and a lignin epoxy resin having an epoxy group added thereto. The purpose is to provide.

  In order to achieve the above object, the lignin derivative of the embodiment comprises a step of suspending a wooden material in an aqueous solution of a metal compound, a step of decomposing the suspension in a high temperature and high pressure, and the reaction solution subjected to the decomposition treatment. And adding a first organic solvent to separate the organic phase and the aqueous phase, and recovering and drying the organic phase.

The flowchart explaining the manufacturing method of the lignin derivative which concerns on this invention. The flowchart explaining the manufacturing method of the lignin derivative which concerns on Example 1 of this invention. The flowchart explaining the manufacturing method of the lignin epoxy resin which concerns on Example 2 of this invention. The figure explaining the chemical reaction of the epoxidized lignin which concerns on Example 2 of this invention.

  A method for producing a lignin derivative according to an embodiment of the present invention will be described with reference to FIG.

  First, water 3 in which a metal compound 2 is dissolved or suspended is added to a wooden material 1 made of lignin or lignocellulose obtained from a known technique. The metal compound 2 is composed of at least one of aluminum sulfate, aluminum chloride, iron chloride, tin chloride, tin sulfate, zinc sulfate, and zinc chloride. This suspension is kept at a high temperature and a high pressure to be decomposed. In the suspension, the partially dissolved metal compound 2 acts as a Lewis acid, hydrolyzes the ether bond of lignin, and converts it from a natural high molecular weight substance to a low molecular weight substance.

  Next, when the first organic solvent 4 is added to the decomposed reaction solution, the phase is separated into an organic phase containing a lignin derivative and an aqueous phase containing a metal compound and a cellulose derivative. The first organic solvent 4 is composed of at least one of methyl ethyl ketone, butanol, and pentanol. Then, the separated organic phase is recovered by filtration and dried, whereby the lignin derivative 5 can be obtained.

  In addition, when the 2nd organic solvent 6 is added to the aqueous solution of the metal compound 2 which suspended the woody material 1 mentioned above, decomposition | disassembly of lignin is accelerated | stimulated and the lignin derivative 5 can be obtained with a high yield. The second organic solvent 6 is composed of at least one of methanol, ethanol, propanol, cresol, phenol, methyl ethyl ketone, and acetone.

  When the epoxy resin 7 and the basic catalyst 8 of the curing catalyst are added to the obtained lignin derivative 5 and heated at a predetermined temperature, a hardened epoxy resin cured product 9 can be obtained. By heating, the epoxy resin 7 and the lignin derivative 5 (phenol resin) proceed in a dissolved state. At this time, even if the acid of the metal compound 2 remains, it is insoluble in these non-aqueous media and does not participate in the curing reaction. The Lewis acidity used for the conversion proceeds with curing without inhibiting the curing reaction.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the manufacturing method of the lignin derivative which concerns on Example 1 of this invention is demonstrated with reference to FIG. FIG. 2 is a flowchart for explaining a method for producing a lignin derivative according to Example 1 of the present invention.

  As shown in FIG. 2, first, the wood material lignocellulose is suspended in an aluminum sulfate aqueous solution of a metal compound (st1). The amount of aluminum sulfate added is 1/3 of the weight of the wood material. This is the amount necessary to cleave the ether bond in lignin in one hour suitable for the conversion step. If necessary, ethanol as a second organic solvent is added to promote decomposition of lignin (st2).

  Next, the suspension is brought into a high-temperature and high-pressure state in an autoclave, and wood is decomposed (st3). The temperature is in the range of 150 to 220 ° C, and preferably 180 ° C. If it is less than 150 degreeC, decomposition | disassembly of lignin does not advance easily, and if it exceeds 220 degreeC, repolymerization and gasification of lignin will occur, and a recovery rate will fall. The pressure is 1.5-2 MPa and is held for 1 hour. In the liquid, partially dissolved aluminum sulfate acts as a Lewis acid, hydrolyzes the ether bond of lignin, and converts what was a high molecular weight product into a low molecular weight product in nature.

  Next, methyl ethyl ketone as the first organic solvent is added to the reaction solution, and the phases are separated (st4). In the phase separation, an organic phase containing a lignin derivative and an aqueous phase containing a metal oxide and a cellulose derivative are separated. From this, the organic phase is recovered by filtration (st5), the solvent is removed and dried (st6), and a lignin derivative can be obtained (st7). When this lignin derivative was analyzed by gas chromatography (GPC), the average molecular weight was 1100, and natural lignin having a molecular weight of about tens of thousands was converted to a low molecular weight form.

  When a lignin derivative converted to a low molecular weight form, a bisphenol A type epoxy resin, and an imidazole-based curing catalyst are dissolved in methyl ethyl ketone and then heated at a predetermined temperature of 120 to 150 ° C., the curing reaction proceeds, A cured product which is removed and cured well can be obtained. Since the reaction of the lignin derivative and the epoxy resin proceeds in a dissolved state, even if aluminum sulfate remains, it is insoluble in the solvent and does not participate in the curing reaction. This is because the Lewis acid used for the conversion does not inhibit the curing reaction. Note that a cured product that cures well can be obtained even in a thermosetting resin such as a polyester resin.

  According to the method for producing a lignin derivative of Example 1 above, lignocellulose is suspended in an aluminum sulfate aqueous solution and decomposed to obtain a lignin derivative, so that the aluminum sulfate acts as a Lewis acid to produce a low molecular weight substance. Even if aluminum sulfate remains in the lignin derivative, it is possible to obtain a cured product of an epoxy resin that hardens without inhibiting the curing reaction.

  Next, the lignin epoxy resin using the lignin derivative which concerns on Example 2 of this invention is demonstrated with reference to FIG. 3, FIG. FIG. 3 is a flowchart for explaining a method for producing a lignin epoxy resin according to Example 2 of the present invention, and FIG. 4 is a diagram for explaining a chemical reaction of an epoxidized lignin according to Example 2 of the present invention. The difference between Example 2 and Example 1 is that an epoxy group was added to the lignin derivative. In each figure, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the lignin derivative 5 is obtained by the same production method (st1) to (st7) as in Example 1. This is dissolved and reacted in epichlorohydrin 12 in the presence of a catalyst of tetrabutylammonium bromide 11 to introduce chlorohydrin ether into the phenolic hydroxyl group. In this case, even if aluminum sulfate remains, the reaction is not hindered and becomes chlorohydrin etherified lignin (intermediate) 13. An epoxidized lignin 15 to which an epoxy group has been imparted can be obtained by adding an excess of aqueous sodium hydroxide solution 14 to cyclize the epoxy group by dehydration and purifying it.

  The epoxidized lignin 15 can be cured with a generally used acid anhydride or amine of a curing agent, or can be cured with the lignin derivative obtained in Example 1. The concept of these chemical reactions is shown in FIG. In addition, the epoxidized lignin which provided the epoxy group is called a lignin epoxy resin.

  According to the lignin epoxy resin of Example 2, the epoxy group can be imparted to the lignin derivative obtained in Example 1.

  According to the embodiment as described above, even if an acid remains in the lignin derivative, a cured product of a thermosetting resin that can be cured firmly without inhibiting the curing reaction can be obtained.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Woody material 2 Metal compound 3 Water 4 1st organic solvent 5 Lignin derivative 6 2nd organic solvent 7 Epoxy resin 8 Basic curing catalyst 9 Cured material 11 Tetrabutylammonium bromide 12 Epichlorohydrin 13 Chlorhydrin etherified lignin 14 Water Sodium oxide 15 Epoxidized lignin

Claims (7)

Suspending a wooden material in an aqueous solution of a metal compound;
A step of decomposing the suspension in a high temperature and high pressure,
Adding a first organic solvent to the decomposed reaction solution, and separating the organic phase and the aqueous phase;
Recovering and drying the organic phase;
A process for producing a lignin derivative, comprising:   The method for producing a lignin derivative according to claim 1, wherein the metal compound is composed of at least one of aluminum sulfate, aluminum chloride, iron chloride, tin chloride, tin sulfate, zinc sulfate, and zinc chloride.   The method for producing a lignin derivative according to claim 1 or 2, wherein the first organic solvent comprises at least one of methyl ethyl ketone, butanol, and pentanol.   The method for producing a lignin derivative according to any one of claims 1 to 3, wherein a second organic solvent is added to the suspension to promote decomposition.   The method for producing a lignin derivative according to claim 4, wherein the second organic solvent comprises at least one of methanol, ethanol, propanol, cresol, phenol, methyl ethyl ketone, and acetone. A cured product of a thermosetting resin,
A lignin derivative recovered by suspending a wooden material in an aqueous solution of a metal compound and decomposing it,
Add bisphenol A type epoxy resin and basic curing catalyst,
A cured product, which is cured by heating at a predetermined temperature. A lignin epoxy resin in which an epoxy group is added to lignin and a wooden material is suspended in an aqueous solution of a metal compound, and the lignin derivative recovered by decomposition treatment is recovered.
Dissolved in epichlorohydrin in the presence of a catalyst of tetrabutylammonium bromide,
A lignin epoxy resin, wherein an aqueous solution of sodium hydroxide is added to the solution to close the epoxy group.

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