JP2011178851A - Water resistant lignin carbide and plastic material containing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water resistant lignin carbide formed by imparting water resistance to a lignin. <P>SOLUTION: The water resistant lignin carbide is formed by subjecting the lignin to hydrothermal treatment and carbonizing the lignin to impart water resistance. Preferably, the hydrothermal treatment is performed on the conditions of ≥300°C temperature and ≥167 kg/m<SP>3</SP>water density. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a water-resistant lignin carbide obtained by hydrothermal treatment of lignin and a plastic material containing the same.

  Production of plastics, which are petroleum-derived materials, is expected to be greatly affected by the oil peak problem in the future. Currently, in order to save even a small amount of petroleum resources, recycling of plastics and the use of biomass as an alternative to petroleum raw materials are being actively studied. In particular, the use of biomass is attracting attention as a means to permanently secure resources in the future. Among them, there is effective utilization of lignin that is currently used for disposal and incineration.

  Lignin is one of the main components of woody biomass and occupies about 20-30% of wood. Most of the lignin is separated and removed as an unnecessary material because it causes discoloration of paper in the pulping process of wood. Discarded or incinerated.

  In Non-Patent Document 1, lignin has a structure in which a p-hydroxyphenylpropane skeleton is bonded by an ether bond or a carbon-carbon bond, and is a polymer having many functional groups such as hydroxyl groups and methoxy groups. It is shown. Patent Documents 1 to 4 show methods for producing various new materials using lignin as a raw material using this structure.

JP 2009-57433 A JP 2009-74082 A JP 2007-5054 A JP 2007-42521 A

Sakakibara, a. , Wood Sci. Technol. , 14, 89 (1980)

  However, when lignin is blended in plastic materials for electrical appliances, particularly plastics such as coating materials for electric wires and cables, the water resistance of the blended compound becomes a problem because lignin contains many hydrophilic parts such as hydroxyl groups.

  Accordingly, an object of the present invention is to provide a water-resistant lignin carbide having improved water resistance of lignin and a plastic material containing the same.

  In order to achieve the above object, the invention of claim 1 is a water-resistant lignin carbide characterized by imparting water resistance by hydrothermally treating and carbonizing lignin.

The invention according to claim 2 is the water-resistant lignin carbide according to claim 1, wherein the hydrothermal treatment is performed under conditions of a temperature of 300 ° C. or more and a water density of 167 kg / m ³ or more.

  The invention according to claim 3 is the water-resistant lignin carbide according to claim 1 or 2, wherein the lignin is an alkaline lignin.

  A fourth aspect of the present invention is a plastic material comprising the water-resistant lignin carbide according to the first to third aspects.

  A fifth aspect of the present invention is a plastic material characterized by containing the water-resistant lignin carbide according to the first to third aspects and used as a plastic material for electrical appliances.

  The invention of claim 6 is a plastic material characterized in that it contains the water-resistant lignin carbide according to claims 1 to 3 as a carbon neutral agent and is used as a coating material for electric wires and cables.

  According to the present invention, water resistance can be imparted to lignin.

It is a schematic diagram of the batch type reactor used by the Example and comparative example of this invention.

  Hereinafter, a preferred embodiment of the present invention will be described in detail.

  The present invention provides water resistance by hydrothermal treatment and carbonization of about 20-30% lignin contained in wood and mainly discarded, and can be suitably used for plastic materials for electrical appliances and the like. It is something that can be done.

  First, a method for producing water-resistant lignin carbide obtained by imparting water resistance to lignin will be described.

  The lignin used in the present invention is particularly preferably alkaline lignin. Alkaline lignin is obtained by extracting lignin from wood flour with an alkaline aqueous solution or an alkali / alcohol solution, and then adding a mineral acid to the extract to cause precipitation. Kraft lignin extracted from wood flour using sodium hydroxide and sodium sulfide and then precipitated by adding mineral acid to the extract is also included in alkaline lignin because its production method is similar. .

  The lignin is hydrothermally treated with water in a batch reactor (hereinafter also referred to as a reactor). By performing the hydrothermal treatment, a hydrophilic portion such as a hydroxyl group is carbonized by dehydration condensation or the like within the lignin molecule or between the molecules, and the lignin is hydrophobized to obtain a water-resistant lignin carbide.

The hydrothermal treatment time is preferably 10 minutes to 50 minutes, and more preferably about 10 minutes to 30 minutes from the viewpoint of mass productivity. The hydrothermal treatment conditions are particularly preferably a temperature of 300 ° C. or higher and a water density relative to the reactor volume (hereinafter, water density) of 167 kg / m ³ or higher. By treating under such hydrothermal treatment conditions, lignin that is completely water-soluble if untreated can be made into a water-resistant lignin carbide having a water absorption of less than 20% and improved water resistance. In addition, the said temperature points out the temperature of the molten salt used at the time of hydrothermal treatment.

  Next, a plastic material to which water-resistant lignin carbide is added will be described.

  By blending the water-resistant lignin carbide produced under the above-described conditions into the plastic material, a plastic material containing the water-resistant lignin carbide can be obtained.

  The blending amount of the water-resistant lignin carbide into the plastic material depends on the product formed from the plastic material, but can be selected within a range that does not cause a problem when used as a product.

  In the present invention, the water-resistant lignin carbide is blended in a coating material for plastic materials, particularly for electric appliances (for electric wires and cables), particularly as a carbon neutral agent.

  Here, the carbon neutral agent means an additive having the properties of carbon neutral, which is considered to have no effect on the increase or decrease in the total amount of carbon dioxide in the atmosphere even when burned. By blending this carbon neutral agent into a compound, it is possible to improve the environmental performance of the compound and the product using the compound.

  Below, the constituent material of the coating | covering material for electric wires and cables which mix | blend the water-resistant lignin carbide | carbonized_material of this invention is described.

  Examples of the base polymer of the wire / cable coating material include polyolefin and modified polyolefin, specifically, low density polyethylene, linear low density polyethylene, linear ultra-low density polyethylene, medium density polyethylene, high density polyethylene, chlorine. Polyethylene, polyvinyl chloride, chlorosulfonated polyethylene, polypropylene, chlorinated polypropylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methacrylate copolymer, ethylene-styrene copolymer, ethylene -Propylene copolymer, ethylene-butene copolymer, ethylene-octene copolymer, maleic acid grafted low density polyethylene, maleic acid grafted linear low density polyethylene, maleic acid grafted ethylene-methyl acrylate copolymer , Maleic acid grafted ethylene-vinyl acetate copolymer, ethylene-maleic anhydride copolymer, ethylene-ethyl acrylate-maleic anhydride terpolymer, ethylene-propylene-butene-1 based on butene-1 Ternary copolymer, ethylene-propylene-diene terpolymer, chloroprene rubber, silicone rubber, butadiene rubber, natural rubber, isoprene rubber, acrylic rubber, hydrogenated styrene-butadiene copolymer, polyester thermoplastic elastomer , Urethane-based thermoplastic elastomers, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, copolymers of ethylene and α-olefins having 4 to 20 carbon atoms, etc., and these may be used alone or in combination of two or more. Can be used. Moreover, it is not limited to these.

  The main additives added to the base polymer include antioxidants, flame retardants, lubricants and the like.

  For example, as the antioxidant, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,4-bis- (n-octylthio) -6 (4-Hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, bis [2-methyl-4- {3-n-alkyl (C12 or C14) thiopropionyloxy} -5- t-butylphenyl] sulfide, 4,4′-thiobis (3-methyl-6-tert-butylphenol) dilaurylthiodipropionate, dimyristylthiodip One or two or more types selected from pionate, distearylthiodipropionate, ditridecylthiodipropionate, and tetrakis (methylenedodecylthiopropionate) methane can be used, but the present invention is not limited thereto. .

  For example, flame retardants include metal hydroxides such as magnesium hydroxide, aluminum hydroxide, calcium hydroxide, barium hydroxide, hydrotalcite, calcium aluminate hydrate, hard clay, melamine, cyanuric acid, isocyanuric Although it can be set as the 1 type (s) or 2 or more types chosen from nonmetallic hydroxides represented by melamine compounds, such as an acid, a melamine cyanurate, a melamine sulfate, and a benzoguanamine, it is not limited to these.

  For example, as the lubricant, erucic acid amide, stearic acid amide, oleic acid amide, erucic acid bisamide, stearic acid bisamide, oleic acid bisamide, ethylene bis stearic acid amide, fatty acid bisamide, fatty acid bisamide, ricinoleic acid, ricinoleic acid Fatty acid metal salts such as calcium and zinc oleate, carnauba wax, montanic acid ester, fatty acid ester such as partially saponified montanic acid ester, ethylene glycol monostearate, polyethylene glycol mono or distearate, glycerin monostearate, trimethylolpropane Polyhydric alcohol fats such as trilaurate, pentaerythritol tetramyristate, soybean oil, linseed oil, epoxidized soybean oil, epoxidized linseed oil Ester, one or may be two kinds or more selected from derivatives of fatty acid esters of polyhydric alcohols, but are not limited thereto.

  In addition to the above, the coating materials include flame retardant aids, surfactants, softeners, plasticizers, inorganic fillers, compatibilizers, stabilizers, lead-free stabilizers for vinyl chloride, crosslinking agents, Additives such as ultraviolet absorbers, light stabilizers, copper damage inhibitors, carbon black, fillers, colorants, processing aids, vulcanization accelerators, vulcanization accelerators, and foaming agents can be further added.

  In short, according to the present invention, water resistance can be imparted to lignin currently mainly discarded, so that it can be suitably blended into plastic materials such as coating materials for electric wires and cables.

  In order to demonstrate the effect of the present invention, lignin carbides obtained by hydrothermal treatment under various conditions were evaluated. The evaluation method and evaluation items are described below.

  Hydrothermal treatment of lignin was performed using a batch reactor (internal volume 6 ml) made of SUS316 shown in FIG. In this batch reactor, a SUS 1/2 inch cap 2 is screwed into the lower end of a SUS 1/2 inch tube 1 to close the lower end of the tube 1, and an SUS 1 / 16-1 is attached to the upper end of the tube 1. A 1/2 inch diameter union 4 is screwed, and a SUS 1/16 inch cap 3 is screwed to the upper end thereof.

  SUS316 used as a material for the reactor contains a metal element such as Fe, Cr, Ni, and Mo. For this reason, when this reactor is used as it is, there is a possibility that metal elements on the inner surface of the reactor are involved in the reaction by the catalytic action, causing an error in the product property evaluation result. Here, an oxidation coating was applied to the inner surface of the reactor for the purpose of reducing errors due to catalytic action. The oxidation treatment was performed by charging about 3 g of 10 mass% hydrogen peroxide water in the reactor and reacting at 673 K for 30 minutes or more.

  In the hydrothermal treatment procedure of lignin, first, a predetermined amount of lignin and water were charged into a batch reactor, and the inside of the reactor was purged with Ar gas. This was poured into a molten salt that had been set to a predetermined temperature in advance, and taken out after a predetermined time and cooled with water. After sufficiently cooling with water, the product in the reactor was recovered with distilled water, and the solid content after filtration was dried in a thermostatic bath to obtain lignin carbide. The water absorption and carbon ratio of this lignin carbide were measured.

The water absorption was measured by placing a sample crushed with a mortar on a previously measured aluminum pan, drying it in a vacuum oven set at 60 ° C. for 12 hours, and then measuring the weight of the dried sample. The aluminum pan on which this sample was placed was placed on a plate in a desiccator filled with water, covered, and then the inside of the desiccator was decompressed with an aspirator to saturate the inside of the desiccator with water vapor. The lid was opened after a predetermined time and the weight of the sample was measured to determine the water absorption of the generated carbide. The water absorption was calculated according to the formula (1).
Water absorption rate (%) = (Water absorption amount (mg) / Dry sample weight (mg)) × 100 Formula (1)

  The carbon ratio was determined by measuring the ratio of C, H, N, and S using an element analyzer Perkin Elmer 2400 II. About 1 mg of the dried sample was wrapped in a tin cup, burned in pure oxygen, separated by a column separation method, and then measured by TCD detection.

The composition of the wire / cable coating material was examined by kneading the lignin carbide produced as described above into the base plastic together with the additive at 180 ° C. for 10 minutes using a 6-inch small roll machine. . A mixer or an extruder may be used for kneading, and the water contained at this time can be volatilized by kneading at a boiling point of water or higher. The compound in which lignin carbide was kneaded was formed into a 1 mm thick sheet by press molding (180 ° C., 5 minutes), and then cut into a square shape to give a weight of about 1.5 g, and the water absorption was evaluated. did. Evaluation of water absorption here was performed in the following procedures. First, the initial weight of the test piece is measured, and the test piece is immersed in an aluminum cup filled with water and sealed. The aluminum cup is stored in a constant temperature bath at 80 ° C., taken out after 7 hours, and water droplets adhering to the surface of the test piece are wiped off. The water absorption was determined by measuring the weight of the test piece after wiping off the water droplets. The water absorption was calculated according to the formula (2).
Water absorption rate (%) = (Water absorption amount (mg) / Initial weight (mg)) × 100 Formula (2)

  Examples 1 to 17, Comparative Examples 1 to 3, and Conventional Example 1 of the present invention will be described below.

In Examples 1 to 17 and Comparative Examples 1 to 3, alkaline lignin (CAS No. 8068-05-1, production number 370959-100G) manufactured by Aldrich was used as the lignin. First, the water density dependency of the carbon ratio and the water absorption rate in the hydrothermal treatment was measured. In this measurement, 0.3 g of alkali lignin and 0 to 3.0 g of water (water density: 0 to 500 kg / m ³ ) were weighed and charged into the batch reactor shown in FIG. The molten salt was heated to 300 ° C. or 400 ° C., and the reaction time (time from the molten salt addition to the start of water cooling) was 30 minutes. Table 1 shows the water absorption and carbon ratio of the lignin carbide obtained under these conditions.

  In Table 1, the judgment is that if the water absorption rate of the lignin carbide after hydrothermal treatment is less than 50%, the water resistance is sufficiently improved (pass: ○), and if it is less than 20%, the coating material for electric wires and cables The water resistance was highly improved to a level that can be applied to the test (pass: double circle). When the water absorption rate of the lignin carbide was 50% or more, the water resistance was not sufficiently improved (failed: x).

  Examples 1 to 8 and Comparative Examples 1 to 3 in Table 1 will be described.

[Example 1]
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 0.5 g of water (water density 83 kg / m ³ ), molten salt temperature 300 ° C. and reaction time 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 72.2%, The water absorption was 20.2%.

[Example 2]
Hydrothermal treatment of 0.3 g of alkaline lignin under conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 300 ° C. and reaction time of 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 72.8%, The water absorption was 16.3%.

Example 3
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 2.0 g of water (water density of 333 kg / m ³ ), molten salt temperature of 300 ° C. and reaction time of 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 75.6%, The water absorption was 7.3%.

Example 4
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 3.0 g of water (water density 500 kg / m ³ ), molten salt temperature 300 ° C. and reaction time 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 74.1%, The water absorption was 5.1%.

Example 5
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 0.5 g of water (water density 83 kg / m ³ ), molten salt temperature 400 ° C. and reaction time 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 82.7%, The water absorption was 33.0%.

Example 6
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 400 ° C. and reaction time of 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 84.4%, The water absorption was 10.4%.

Example 7
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 2.0 g of water (water density of 333 kg / m ³ ), molten salt temperature of 400 ° C. and reaction time of 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 83.3%, The water absorption was 6.4%.

Example 8
Hydrothermal treatment of 0.3 g of alkaline lignin under conditions of 3.0 g of water (water density 500 kg / m ³ ), molten salt temperature 400 ° C., and reaction time 30 minutes revealed that the lignin carbide after treatment had a carbon ratio of 85.2%, The water absorption was 2.1%.

[Comparative Example 1]
When the carbon ratio of the alkali lignin before hydrothermal treatment was measured, it was 51.4%. Further, the water absorption rate could not be measured because the alkaline lignin was dissolved in water.

[Comparative Example 2]
When 0.3 g of alkaline lignin was heat-treated without water, at a molten salt temperature of 300 ° C. and for a reaction time of 30 minutes, the treated lignin carbide had a carbon ratio of 62.7% and a water absorption of 75.6%.

[Comparative Example 3]
When 0.3 g of alkali lignin was heat-treated without water, at a molten salt temperature of 400 ° C. and for a reaction time of 30 minutes, the lignin carbide after the treatment had a carbon ratio of 74.7% and a water absorption of 163.7%.

  From Examples 1 to 8, it was found that the water absorption rate of lignin can be sufficiently reduced by hydrothermal treatment. Moreover, the alkaline lignin itself is so hydrophilic that it shows water solubility from Comparative Example 1, and from Comparative Examples 2 and 3, the water absorption rate of lignin cannot be sufficiently reduced only by heat treatment (without using water). I understood.

Furthermore, it was found that if the water density is 167 kg / m ³ or more, the water absorption can be reduced to less than 20% regardless of the temperature. Further, since the carbon ratio increases with the increase in water density, the decrease in water absorption is considered to be due to the improvement in hydrophobicity due to the promotion of carbonization. Therefore, in the further examination, alkali lignin was hydrothermally treated at a water density of 167 kg / m ³ .

  Next, the reaction time dependence of the carbon ratio and water absorption rate in hydrothermal treatment was measured.

In this measurement, 0.3 g of alkali lignin and 1.0 g of water (water density: 167 kg / m ³ ) were weighed and charged into the batch reactor described above. The molten salt was heated to 300 ° C. or 400 ° C., and the reaction time (time from the molten salt addition to the start of water cooling) was 10 to 50 minutes. Table 2 shows the carbon ratio and water absorption rate of the lignin carbide obtained under these conditions. The determination criteria were the same as in Examples 1-8.

  Examples 9 to 16 in Table 2 will be described.

Example 9
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 300 ° C. and reaction time of 10 minutes revealed that the lignin carbide after treatment had a carbon ratio of 70.9%, The water absorption was 18.8%.

Example 10
Hydrothermal treatment of 0.3 g of alkaline lignin under conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 300 ° C. and reaction time of 20 minutes revealed that the lignin carbide after treatment had a carbon ratio of 71.8%, The water absorption was 16.2%.

Example 11
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 300 ° C. and reaction time of 40 minutes revealed that the lignin carbide after treatment had a carbon ratio of 73.3%, The water absorption was 15.2%.

Example 12
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 300 ° C. and reaction time of 50 minutes revealed that the lignin carbide after treatment had a carbon ratio of 74.0%, The water absorption was 11.9%.

Example 13
Hydrothermal treatment of 0.3 g of alkaline lignin under conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 400 ° C. and reaction time of 10 minutes revealed that the lignin carbide after treatment had a carbon ratio of 79.6%, The water absorption was 16.2%.

Example 14
Hydrothermal treatment of 0.3 g of alkaline lignin under conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 400 ° C. and reaction time of 20 minutes revealed that the lignin carbide after treatment had a carbon ratio of 83.2%, The water absorption was 10.0%.

Example 15
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 400 ° C. and reaction time of 40 minutes revealed that the lignin carbide after treatment had a carbon ratio of 83.0%, The water absorption was 14.4%.

Example 16
Hydrothermal treatment of 0.3 g of alkaline lignin under the conditions of 1.0 g of water (water density: 167 kg / m ³ ), molten salt temperature of 400 ° C. and reaction time of 50 minutes revealed that the lignin carbide after treatment had a carbon ratio of 83.7%, The water absorption was 19.5%.

  From Table 2, it was found that the water absorption was less than 20% in 10 to 50 minutes regardless of the reaction temperature. Further, it was found that even in a reaction time of 10 to 30 minutes, which is a relatively short time, carbonization is promoted to some extent and hydrophobicity is improved, and the water absorption is less than 20%.

  Next, in order to examine the applicability of lignin carbide to wire / cable coating materials, lignin carbide was blended as a carbon neutral agent in wire / cable coating materials, and the water absorption of the compounds was evaluated.

The lignin carbide used here is 0.3 g of alkaline lignin in water of 1.0 g (water density: 167 kg / m ³ ), molten salt temperature of 300 ° C., reaction time of 30 minutes (ie, conditions of Example 2). Heat-treated. Table 3 shows the recipe and evaluation results. Judgment criteria for evaluation results are acceptable if the water absorption is less than 4% (possible application to coating materials for electric wires and cables), and rejected if it is 4% or more (application to coating materials for electric wires and cables) Is difficult).

  Further, Conventional Example 1 and Comparative Example 4 in Table 3 were performed in order to relatively evaluate the water absorption of the compound of Example 17.

  Example 17 in Table 3, Conventional Example 1, and Comparative Example 4 will be described.

Example 17
Base polymer 100 parts ethylene vinyl acetate copolymer (EVA), 32 parts magnesium hydroxide as flame retardant, 35 parts lignin carbide as carbon neutral agent, 0.5 part phenolic antioxidant as antioxidant, as lubricant Fatty acid amide 0.2 part and carbon 5 part as a coloring agent were mixed. The water absorption was measured and found to be 3.1%.

[Conventional example 1]
As a blend of general wire / cable coating materials that do not contain lignin-modified products that are carbon neutral agents, 100 parts of ethylene vinyl acetate copolymer (EVA) as base polymer, 67 parts of magnesium hydroxide as flame retardant and antioxidant As a compound, 0.5 part of a phenolic antioxidant, 0.2 part of fatty acid amide as a lubricant, and 5 parts of carbon as a colorant were prepared. The water absorption of this compound was measured and found to be 0.5%.

[Comparative Example 4]
As a blend using Vanillex N (sodium lignin sulfonate) manufactured by Nippon Paper Chemicals Co., Ltd. as a carbon neutral agent as a hydrophobized lignin modified product, a compound is produced by replacing the lignin carbide in the blend shown in Example 17. did. The water absorption of this compound was measured and found to be 8.5%.

  Even if lignin carbide is blended as a carbon neutral agent as in Example 17, it is considered that the application as a wire / cable coating material is at a sufficiently possible level. Moreover, the lignin carbide used in Example 17 is a lignin carbide obtained under the conditions of Example 2, and the water absorption rate of the lignin carbide itself is 16.3%. Thus, in Table 1, the water absorption rate of the lignin carbide itself obtained in Examples 3, 4, 6, 7, and 8 is smaller than the water absorption rate of the lignin carbide itself obtained under the conditions of Example 2. Similarly, when compounded as a carbon neutral agent, it can be easily imagined that the water absorption rate of the compound is 3.1% or less, and it is considered that application as a wire / cable coating material is sufficiently possible. Even when the lignin carbide obtained in Examples 9 to 16 in Table 2 was blended as a carbon neutral agent in the same manner as in Example 17, the water absorption rate of the lignin carbide itself was almost the same as the lignin carbide obtained under the conditions of Example 2. For this reason, it is considered possible to apply it as a wire / cable coating material.

  In other words, it becomes possible to produce an electric wire / cable covering material that is more environmentally friendly than the prior art by blending a carbon neutral agent.

  From the results of Conventional Example 1 and Comparative Example 4, in the case of the present blending amount, if a lignin carbide obtained by hydrothermally treating alkaline lignin as shown in Example 17 is used as a carbon neutral agent, the conventional carbon neutral agent is included. Although the water absorption rate is slightly higher than that of non-compounds, it is sufficiently applicable as a coating material for electric wires and cables, and the water absorption rate of the compound can be suppressed to ½ or less compared to commercially available hydrophobized lignin modified products. I understood. In addition, it is possible to reduce the water absorption rate of the compound by reducing the blending amount of commercially available hydrophobized lignin modified products, but only a very small amount can be blended, compared to hydrothermally treated lignin carbide. It seems that the use effect is not so much.

As described above, according to the present invention, the water absorption rate of lignin can be greatly suppressed, and if the water density is 167 kg / m ³ or more, the water resistance can be improved to a high degree. As an agent, it can be expected to be applied to coating materials for electric wires and cables. Moreover, it can be said that this invention is the outstanding environmental consideration technique from a viewpoint of effective utilization of biomass resources.

Claims (6)

  A water-resistant lignin carbide characterized by imparting water resistance by hydrothermal treatment and carbonization of lignin. The water-resistant lignin carbide according to claim 1, wherein the hydrothermal treatment is performed under conditions of a temperature of 300 ° C. or more and a water density of 167 kg / m ³ or more.   The water-resistant lignin carbide according to claim 1 or 2, wherein the lignin is an alkaline lignin.   A plastic material comprising the water-resistant lignin carbide according to claim 1.   A plastic material comprising the water-resistant lignin carbide according to claim 1 to 3 and used as a plastic material for electrical appliances.   A plastic material comprising the water-resistant lignin carbide according to any one of claims 1 to 3 as a carbon neutral agent and used as a coating material for electric wires and cables.

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