JP2011184230A - Lignin-based concrete admixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete admixture which has no limitation about the kinds of lignin to be used as a raw material and has higher performances than a conventional lignosulfonic acid-based concrete admixture. <P>SOLUTION: The concrete admixture essentially comprises a lignin derivative produced by the reaction of lignin and a hydrophilic compound. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an admixture for concrete. Specifically, the present invention relates to a concrete admixture mainly composed of a lignin derivative.

  Lignin is one of the main components of plant biomass such as wood and is said to be the second most organic polymer compound on the ground after cellulose. The specific structure of lignin is p-coumalyl alcohol / coniphenyl, among the phenylpropanoids synthesized by further metabolism (secondary metabolism) of carbon compounds assimilated by photosynthesis (primary metabolism). The lignin monomer, which is the three basic units of alcohol and sinapyrcohol, is oxidized one-electron under the catalyst of the enzyme (laccase, peroxidase, etc.) to become a phenoxy radical, which is highly polymerized by random radical coupling. It is a huge biopolymer that forms a complex three-dimensional network structure.

  Lignin has different basic unit types, ratios, and binding forms depending on the type of plant derived from, for example, a woody plant or a herbaceous plant, and the lignin structure is different. Furthermore, even if it is a woody plant, it is a conifer or a broad-leaved tree, and even if it is these conifers, whether it is a cedar or a cypress, the lignin structure also depends on the species of lignin used as a raw material. Is different.

  Lignin can be isolated by chemically treating the raw material, but the lignin structure obtained also varies depending on the isolation method.

  As mentioned above, the molecular structure of lignin is complex, and the use of lignin as a material is limited because the molecular properties of lignin vary greatly depending on the isolation method used for isolation from plant biomass. ing. Furthermore, lignin is hydrophobic in nature, and its use is limited because it is difficult to dissolve in water.

  As an example of the use of lignin, conventionally, concrete admixtures (AE agent and water reducing agent) mainly composed of lignin sulfonate are known. Both the AE agent and the water reducing agent are a kind of surfactant. Surfactants are classified into four types, anionic surfactants, cationic surfactants, zwitterionic surfactants, and nonionic surfactants. As AE agents and water reducing agents, Anionic or nonionic surfactants are utilized.

  Lignin sulfonate is an ionic (anionic) surfactant that ionizes sulfonic acid groups in water, but it is difficult to control the structure of the lignin part, which is a hydrophobic part, and its performance as an admixture for concrete Has its limits. In addition, lignin sulfonic acid is a lignin compound that is discharged from a paper pulping method called sulfite cooking, but sulfite cooking methods have problems in terms of drug recovery, etc. As a result, the supply of lignin sulfonic acid as a by-product is not sufficient.

  In recent years, it has been required to easily obtain an admixture for concrete having performance according to the cement material to be used and the purpose of construction in response to the deterioration of aggregate conditions and the advancement and diversification of cement technology.

Special table 2008-514402

  An object of the present invention is to obtain a concrete admixture that is not limited in the type of lignin used as a raw material and has higher performance than conventional lignin sulfonic acid concrete admixtures.

  As a result of various studies by the present inventors, an amphiphilic lignin derivative obtained by introducing a hydrophilic group into a hydrophobic lignin exhibits the properties of a nonionic surfactant, and is used as an admixture for concrete. The present invention was completed by finding that it exhibits excellent performance.

The present invention provides the following.
(1) A concrete admixture mainly composed of a lignin derivative produced by a reaction between lignin and a hydrophilic compound.
(2) The hydrophilic compound is represented by the following formula (I):
^{_{R 1 -C m H 2m - (}} C n H 2n O) p -C q H 2q -R 2 (I)
[Wherein, R ¹ and R ² are each independently a hydrogen atom, OH group, methyl group, glycidyl group or glycidyl ether group, m is 0 to 20, n is 2 to 4, p Is 1-30, q is 0-20, and each carbon atom of the alkylene unit is independently selected from an alkyl group, —OH group, —NH ₂ group, glycidyl group, or glycidyl ether group 1 or May have two substituents]
In this case, mixed alkoxide units may be formed, in which case the order of the alkoxide units is arbitrary.
The admixture for concrete according to the above (1).
(3) The admixture for concrete according to the above (1), wherein the hydrophilic compound is a glycidyl ether compound or a glycol compound.
(4) The admixture for concrete according to (1) above, wherein the hydrophilic compound is poly (ethylene glycol) diglycidyl ether.
(5) The concrete admixture according to (1) above, wherein the hydrophilic compound is poly (glycerin).
(6) The concrete admixture according to any one of (1) to (5) above, wherein the lignin is craft lignin, acetate lignin, organosolv lignin, explosive lignin, sulfate lignin, or alkali lignin.
(7) A method for producing an admixture for concrete comprising a lignin derivative as a main component, wherein lignin and a glycidyl ether compound are reacted under an alkaline condition.
(8) A method for producing an admixture for concrete comprising a lignin derivative as a main component, wherein lignin and a glycol compound are reacted under acidic conditions.
(9) A cement water reducing agent mainly comprising a lignin derivative produced by a reaction between lignin and a hydrophilic compound.

  According to the present invention, a high-performance concrete admixture can be easily produced, which is industrially advantageous. Moreover, according to the present invention, the type of lignin as a raw material is not limited, and it is industrially advantageous in that a currently unused lignin can be used effectively. Furthermore, according to the present invention, by using an arbitrary hydrophilic compound as a raw material, it is possible to easily obtain an admixture for concrete having performance according to the cement material to be used and the construction purpose. Industrially advantageous.

FIG. 1 shows the fluidity of concrete with respect to the amount of admixture for concrete.

(Lignin)
As the lignin in the present invention, any lignin can be used, for example, kraft lignin, acetate lignin, organosolv lignin, explosive lignin and the like isolated from wood chips by pulping treatment; Examples include, but are not limited to, sulfated lignin and alkaline lignin. Also, lignin of any origin can be used, for example, conifer lignin such as cedar, cypress and pine; broad-leaved lignin such as beech and oak; and herbaceous lignin such as rice straw, fir and bagasse, It is not limited to these.

  The lignin used in the present invention can be obtained by isolation from a raw material using a method known in the art, for example, the method described in “Lignin Chemistry (Nakano Junzo Hen Uni Uni Publishing)”. it can.

  The molecular weight of lignin depends on its source material and isolation method. As the lignin used in the present invention, lignin having an arbitrary molecular weight can be used. For example, lignin having an average molecular weight of 500 to 1,000,000, preferably lignin having an average molecular weight of 5,000 to 100,000 can be used. it can.

(Hydrophilic compound)
The hydrophilic compound which is a starting material of the lignin derivative of the present invention means a compound containing at least one hydrophilic group such as —OH, —O—, —NH _{2 in the} molecule. Preferably, the hydrophilic compound has the following formula (I):
^{_{R 1 -C m H 2m - (}} C n H 2n O) p -C q H 2q -R 2 (I)
[Wherein, R ¹ and R ² are each independently a hydrogen atom, OH group, methyl group, glycidyl group or glycidyl ether group, m is 0 to 20, n is 2 to 4, p Is 1-30, q is 0-20, and each carbon atom of the alkylene unit is independently selected from an alkyl group, —OH group, —NH ₂ group, glycidyl group, or glycidyl ether group 1 or May have two substituents]
In this case, mixed alkoxide units may be formed. In this case, the order of the alkoxide units is arbitrary.

Examples of hydrophilic compounds used in the present invention include, but are not limited to, the following compounds:
Glycol compounds such as ethylene glycol, diethylene glycol, polyethylene glycol of various molecular weights, propylene glycol, polypropylene glycol of various molecular weights, glycerin, polyglycerin of various molecular weights; and methyl glycidyl ether, ethyl glycidyl ether, propyl glycidyl ether, 2-ethylhexyl glycidyl Monofunctional glycidyl ether compounds such as ether, decyl glycidyl ether, stearyl glycidyl ether, polyethylene glycol-monoethyl-glycidyl ether, polyethylene glycol-monomethyl-glycidyl ether, lauryl alcohol-polyethylene oxide-glycidyl ether,
Ethylene glycol-diglycidyl ether, poly (ethylene glycol) diglycidyl ether (n ′ = 1-30, preferably 9-30), propylene glycol diglycidyl ether, poly (propylene glycol) diglycidyl ether (n ′ = 1- 30, preferably 9-30), neopentyl glycol diglycidyl ether, 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, 1,6- Hexanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, 1,4-cyclohexanediol diglycidyl ether, 1,3-cyclohexanediol diglycidyl ether, glycerol diglycidyl Ether, pentaerythritol diglycidyl ether, bifunctional glycidyl ether compounds such as sorbitol diglycidyl ether,
Glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, tertiary carboxylic acid glycidyl ester, 1,1,1-tris (hydroxymethyl) ethanetriglycidyl ether, 1,1,1 -Tris (hydroxymethyl) ethane diglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, phloroglucinol triglycidyl ether, pyrogallol triglycidyl ether, cyanuric acid triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol Polyfunctional glycidyl ether compounds such as tetraglycidyl ether, and these glycidyl A glycidyl ether compound in which the functionality of a glycidyl ether group is lowered by reacting a group with an alkoxide such as methoxy or ethoxy.

  As these hydrophilic compounds, commercially available compounds may be used, or those prepared by methods known in the art may be used. These hydrophilic compounds are included in the compound of the above formula (I).

  The lignin derivative of the present invention can control the performance as an admixture for concrete obtained by arbitrarily selecting and preparing these hydrophilic compounds.

  In a preferred embodiment of the invention, the hydrophilic compound is poly (ethylene glycol) diglycidyl ether.

  In a preferred embodiment of the present invention, the hydrophilic compound is poly (ethylene glycol) diglycidyl ether having 1 to 20 ethylene oxide repeating units.

  In a preferred embodiment of the present invention, the hydrophilic compound is a poly (ethylene glycol) diglycidyl ether having 5 to 15 repeating units of ethylene oxide.

  In a preferred embodiment of the present invention, the hydrophilic compound is poly (ethylene glycol) diglycidyl ether having 13 ethylene oxide repeating units.

  In a more preferred embodiment of the present invention, the hydrophilic compound is a monofunctionalized poly (ethylene glycol) diglycidyl ether having 13 ethylene oxide repeating units with an alkoxide having 1 to 3 carbon atoms.

  In a more preferred embodiment of the invention, the hydrophilic compound is poly (ethylene glycol) monoethyl-glycidyl ether.

In a preferred embodiment of the present invention, the hydrophilic compound is ethoxy- (2-hydroxy) -propoxy-polyethylene glycol glycidyl ether having 13 ethylene oxide repeat units.
In a preferred embodiment of the present invention, the hydrophilic compound is polyglycerin.

(Lignin derivative)
The amphiphilic lignin derivative of the present invention can be obtained by reacting lignin with a hydrophilic compound to introduce a hydrophilic group into the hydrophobic lignin. As a method for introducing a hydrophilic group into lignin, a known method for reacting a reactive group in a hydrophilic compound with a hydroxyl group in lignin can be used.

  In the reaction of the present invention, the amount of the hydrophilic compound to be reacted with lignin can be determined depending on the type of lignin and hydrophilic compound used and the performance of the target concrete admixture. The amount of the hydrophilic compound to be added is calculated based on the amount of the hydroxyl group in the lignin used and the amount of the glycidyl group or hydroxyl group in the hydrophilic compound to be added. Theoretically, all hydroxyl groups in lignin can react with glycidyl groups or hydroxyl groups in hydrophilic compounds. The amount of the hydrophilic compound is not limited, but is usually 5 to 100 parts by weight of glycidyl compound with respect to 10 parts by weight of lignin, preferably 10 to 60 parts by weight of glycidyl compound with respect to 10 parts by weight of lignin, more preferably The amount of glycidyl compound is 30 to 40 parts by weight with respect to 10 parts by weight of lignin.

  When using a glycidyl ether compound as the hydrophilic compound, by dissolving lignin in an aqueous alkaline solution and reacting the hydroxyl group (lignin-OH) in the lignin liberated under alkaline conditions with the glycidyl group in the glycidyl ether compound, Lignin derivatives can be prepared. The black liquor obtained after alkali digesting lignocellulosic biomass can also be used as the alkaline aqueous solution of lignin.

  Although reaction temperature is not specifically limited, Usually, 50 to 100 degreeC, Preferably it is 70 degreeC.

  The reaction time is not particularly limited, but is usually 30 minutes to 24 hours, preferably 1 hour to 12 hours, and more preferably 3 hours to 6 hours.

  In the reaction of the present invention, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, lithium hydroxide or the like can be used to make the alkaline condition.

  In this reaction, after the reaction between lignin and a glycidyl compound is completed, an acid is added to the reaction system to neutralize it. The acid to be added may be any acid as long as it does not have an adverse effect. For example, inorganic acids such as hydrochloric acid, phosphoric acid and sulfuric acid, and organic acids such as formic acid and acetic acid can be used.

  This reaction is completed when the obtained lignin derivative becomes hydrophilic due to the introduction of the hydrophilic compound into the hydrophobic lignin. Completion of the reaction between the lignin and the hydrophilic compound can be determined, for example, by whether or not precipitation occurs when the pH is lowered by adding an acid to a sample of the solution during the reaction. When the reaction is insufficient, unreacted lignin is deposited as a precipitate. When the reaction is completed, no precipitation occurs and an amphiphilic lignin derivative is obtained.

  In one embodiment of the present invention, lignin is dissolved in an aqueous sodium hydroxide solution, the resulting alkaline aqueous solution of lignin is warmed to about 70 ° C. under normal pressure, a predetermined amount of glycidyl ether compound is added, and the mixture is stirred for about 3 hours. Then, after the reaction is completed, the reaction system is neutralized by adding an acid to obtain a lignin derivative.

  In the case of using a glycol compound as the hydrophilic compound, a lignin derivative can be prepared by adding an acid catalyst to a mixture of lignin and a glycol compound to cause a reaction.

  As the acid catalyst, hydrochloric acid, sulfuric acid or the like can be used. The addition amount is usually 0.1 to 3.0% by weight with respect to the glycol compound.

  Although reaction temperature is not specifically limited, Usually, it is 100 to 200 degreeC, Preferably it is 120 to 160 degreeC, More preferably, it is 140 degreeC.

  Although reaction time is not specifically limited, Usually, 30 minutes-180 minutes, Preferably it is 60 minutes-120 minutes, More preferably, it is 90 minutes.

  In this reaction, it is preferable to remove water-insoluble parts by adding water to the reaction system after completion of the reaction between lignin and the glycol compound.

  The lignin derivative obtained by the above reaction can be used as it is as an admixture for concrete, and if necessary, can be subjected to ultrafiltration for desalting and removal of unreacted hydrophilic compounds. it can. For example, it is preferable to perform filtration using an ultrafiltration device that can exclude a molecular weight of 3000 or less.

  The lignin derivative obtained by the reaction may be completely dried by a conventionally used drying method such as a freeze dryer, if necessary.

  A schematic diagram of a lignin derivative obtained when ethoxy- (2-hydroxy) -propoxy-polyethylene glycol glycidyl ether is used as the hydrophilic compound is as follows.

(Admixture for concrete)
Specifically, the concrete admixture means an AE agent, a high performance water reducing agent, a curing accelerator, a water reducing agent, an AE water reducing agent, a high performance AE water reducing agent, and a fluidizing agent (JIS A 6204: 2006). AE agent is a surfactant with excellent bubble stability related to the bubble property due to the decrease in surface tension and the strength of the molecular film oriented at the interface, and fine closed cells are uniformly distributed in the concrete. And improve concrete workability and resistance to freezing and thawing. A water reducing agent is a surfactant that is excellent in dispersing or wetting action, and adsorbs on the cement particle surface to form an electric double layer or form a solvation layer around the cement particle to disperse the cement particle. Significantly improves the workability of A water reducing agent with an AE agent is called an AE water reducing agent.

  When the lignin derivative of the present invention is used as an admixture for concrete, it may be used in the form of an aqueous solution or may be used after pulverized. In addition, the pulverized concrete admixture of the present invention is blended in advance with a water-free cement composition such as cement powder or dry mortar, and used as a premix product for plastering, floor finishing, grout and the like. Alternatively, it may be blended when the cement composition is kneaded.

  Preferably, the concrete admixture based on the lignin derivative of the present invention is used in the form of an aqueous solution. Although the density | concentration of aqueous solution is arbitrary, it is 5 to 50%, for example, Preferably, it is about 10 to 30%.

  The amount of the admixture for concrete of the present invention when added to cement is arbitrary, but for example, 0.01 to 10.0% by mass, preferably 0, based on the mass of cement in terms of solid content. 0.02 to 5.0 mass%, more preferably 0.1 to 1.0 mass%. Such a blending amount brings various preferable effects such as a reduction in unit water amount, an increase in strength, and an improvement in durability in ordinary general-purpose cement. In particular, when the blending amount is 0.1% by mass or more, the fluidity is remarkably imparted, and therefore, the effect as a so-called cement water reducing agent is excellent and preferable.

  In the concrete admixture of the present invention, conventionally known additives may be blended as long as the performance is not impaired. Examples of conventionally known additives include antifoaming agents, air entraining agents, wetting agents, waterproofing agents, and viscosity modifiers. These additives may be used alone or in combination of two or more.

  The admixture for concrete of the present invention can be used for cement compositions such as cement, gypsum and plaster, mortar, concrete and the like containing fine aggregate (sand, etc.) and coarse aggregate (crushed stone, etc.). That is, the concrete admixture of the present invention can also be used as a cement water reducing agent.

  The cement used in the cement composition is not particularly limited, and specific examples include, for example, Portland cement (ordinary, early strength, very early strength, moderate heat, sulfate resistance, and respective low alkalis). ), Various mixed cements (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, super fast cement (1 clinker fast cement, 2 clinker fast cement, magnesium phosphate cement), grout cement , Oil well cement, low exothermic cement (low exothermic blast furnace cement, fly ash mixed low exothermic blast furnace cement, high content belite cement), ultra high strength cement, cement-based solidified material, eco-cement (city waste incineration ash, sewage sludge) Cement produced from one or more types of incinerated ash) And the like. Furthermore, fine powder such as blast furnace slag, fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, limestone powder, or gypsum may be added to the cement composition. Aggregates include gravel, crushed stone, granulated slag, recycled aggregate, etc., as well as silica, clay, zircon, high alumina, silicon carbide, graphite, chrome, chromia, magnesia Refractory aggregates such as can be used.

In the cement composition, the unit water amount per 1 m ³ , the amount of cement used and the water / cement ratio (mass ratio) are preferably 100 kg / m ^{3 to} 185 kg / m ³ , more preferably 120 kg / m. ^{3 ~175kg} / ^{m 3,} preferably used amount of cement is ^{200kg / m 3 ~800kg / m 3} , more preferably from ^{250kg / m 3 ~800kg / m 3} , water / cement ratio (mass ratio) is preferably 0 0.1 to 0.7, more preferably 0.2 to 0.65, which can be used widely from poor blends to rich blends. The concrete admixture of the present invention has a high water reduction rate region, that is, a low water / cement ratio such as a water / cement ratio (mass ratio) of 0.15 to 0.5 (preferably 0.15 to 0.4). It can also be used in the region, and is effective for both high-strength concrete having a large unit cement amount and a small water / cement ratio, and poor blended concrete having a unit cement amount of 300 kg / m ³ or less.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
(Preparation of lignin solution)
As lignin, alkaline lignin purified from cooking black liquor obtained by alkaline digestion of cedar chips was used. Alkaline digestion is a technique employed as a pretreatment when producing bioethanol from cedar wood. 10 g of alkaline lignin was dissolved in 100 mL of 1N aqueous sodium hydroxide solution at room temperature with stirring.

(Preparation of glycidyl ether compounds)
24 g of polyethylene glycol diglycidyl ether having an ethylene oxide repeating unit of 13 (manufactured by Nagase ChemteX Corp., Denacol EX-841) was added to 20 mL of acetone and heated to 50 ° C. with stirring. Next, 1.36 g of sodium ethoxide was dissolved in 12 mL of ethanol and heated to 50 ° C. A sodium ethoxide solution was added dropwise over 20 minutes to a glycidyl ether compound acetone solution heated to 50 ° C., and the mixture was further stirred at the same temperature for 10 minutes. After neutralizing the solution with acetic acid, the solvent was removed with a rotary evaporator, vacuum drying was performed in a desiccator for 24 hours, and a glycidyl ether compound (ethoxy- (2-hydroxy) -propoxy-polyethylene monofunctionalized with ethoxy). Glycol glycidyl ether).

(Lignin derivatization)
22 g of the monofunctional glycidyl ether compound prepared by the above method was added to the above 10 g alkaline lignin 1N aqueous sodium hydroxide solution. The solution was heated to 70 ° C. and stirred for 3 hours to react. The reaction was terminated by adding acetic acid to bring the pH to 4. The solution was filtered using an ultrafiltration apparatus equipped with an ultrafiltration membrane excluding a molecular weight of 1000 or less. After filtration, the residue was collected and lyophilized to obtain about 22 g of lignin derivative.

Example 2
A lignin derivative was prepared in the same manner as in Example 1 except that lignin (kraft lignin) obtained as a by-product at the time of kraft cooking for producing paper pulp was used instead of the alkaline lignin used in Example 1. Kraft lignin used was broad-leaved kraft lignin from MeadWestvaco.

Example 3
A lignin derivative was prepared in the same manner as in Example 1 except that instead of the alkaline lignin used in Example 1, acetic acid was used as a cooking liquor and acetic acid lignin produced as a by-product was used. Acetic acid pulp is obtained by digesting birch chips with acetic acid in a 100 L digester.

Example 4
As the glycidyl ether compound used in Example 1, polyethylene glycol diglycidyl ether having a repeating unit of ethylene oxide of 13 (manufactured by Nagase ChemteX Corporation, Denacol EX-841) is not monofunctionalized, but is used as a bifunctional compound as it is. used. To the 10 g alkaline lignin 1N sodium hydroxide solution shown in Example 1, 10 g of the above bifunctional glycidyl compound was added. The solution was heated to 70 ° C. and stirred for 3 hours to react. The reaction was terminated by adding acetic acid to bring the pH to 4. The solution was filtered using an ultrafiltration apparatus equipped with an ultrafiltration membrane that excludes a molecular weight of 1000 or less. After filtration, the residue was collected and lyophilized to obtain about 15 g of lignin derivative.

Example 5
(Derivatization with glycol compounds)
A glycol reagent was prepared by adding 0.25 g of concentrated sulfuric acid to 50 g of polyethylene glycol having an average molecular weight of 400 and stirring well at room temperature and normal pressure. 50 g of the above glycol-based reagent was added to 10 g of alkaline lignin, and the mixture was heated to 140 ° C. while stirring under normal pressure. After heating for 90 minutes, the reaction layer was cooled with water. After cooling, the contents were sucked out with a dropper and dropped into 1 liter of distilled water stirred vigorously with a stirrer. The distilled water was filtered through a glass filter having a pore size of 16 to 40 μm to remove the water-insoluble part. The obtained aqueous solution was filtered using an ultrafiltration apparatus that excludes a molecular weight of 1000 or less. After filtration, the residue was collected and lyophilized to obtain about 5 g of lignin derivative.

  The following performance evaluation was performed using the obtained lignin derivative as an admixture for concrete.

Test Example 1:
Confirmation of water reduction effect by flow test In the performance test of the admixture for concrete, a cement flow test was conducted according to the JIS method (cement physical test method JIS-R5201). As a comparison of the admixture, a commercially available lignin sulfonic acid-based admixture (Pozoris No8: BASF Pozzolith Co., Ltd.) and a commercially available lignin sulfonate (Sun Extract: Nippon Paper Chemicals Co., Ltd.) were used. The admixture of the present invention, the commercial admixture, and the commercial lignin sulfonic acid were each dissolved in water to prepare a 20% solution. The cement used was Sumitomo Osaka Cement (density: 3.15 kg / cm3). The following tests were conducted in a test room adjusted to 20 ° C., and the cement and water used were also adjusted to 20 ° C.

  Cement (976 g), water (341 g), and an admixture aqueous solution weighed so that the admixture was 0.1 to 1% with respect to cement were added, and mechanical kneading was performed according to the JIS method (low speed (120 seconds) → (Scraping 20 seconds) → low speed (120 seconds) → (scraping 20 seconds)). The kneaded cement paste was immediately subjected to a flow test.

  In the flow test, the relative area flow value was determined to examine the performance of the admixture. The glass plate was placed horizontally and the flow cone was placed in the center. The paste was packed twice. Each layer pierced 15 times so that one-half of the tip of the wand entered the layer. The second layer compensates for the deficiency and smoothes the surface. The flow cone was removed vertically, and the diameter was measured at two locations in the vertical direction to obtain the average value. The flow test was performed twice under the same conditions, and the average was obtained.

  FIG. 1 shows the results of a cement flow test with respect to the amount of admixture added. The admixture composed of the lignin derivative prepared in Example 1 showed fluidity superior to the two admixtures used as comparisons. Considering that a commonly used concentration of this type of admixture is about 0.25% addition, the admixture of the present invention has been shown to be about 2-3 times more potent than commercial products. In view of the fact that the commercially available lignin sulfonic acid-based admixture contains various admixtures in addition to the lignin sulfonate of the active ingredient, it is surprising that the lignin derivative of the present invention alone exhibits the above performance. It is to be done.

  The admixture composed of the lignin derivative prepared in Examples 2 and 3 also showed performance exceeding the commercially available product. The admixture composed of the lignin derivative prepared in Example 4 showed the same performance as the commercial product. The admixture composed of the lignin derivative prepared in Example 5 showed the same performance as the commercial product.

  The lignin derivative of the present invention exhibits superior performance as a concrete admixture over commercially available concrete admixtures. Moreover, the kind of raw material lignin at the time of manufacturing the lignin derivative of this invention is not limited. Since a wide variety of lignins produced as a by-product in paper pulping technology and bioethanol production can be used, it can contribute to the overall utilization of biomass. Furthermore, according to the present invention, by using any hydrophilic compound as a raw material, it is possible to easily obtain a concrete admixture having performance according to the cement material to be used and the construction purpose.

Claims (8)

  A concrete admixture mainly composed of a lignin derivative produced by a reaction between lignin and a hydrophilic compound. The hydrophilic compound is represented by the following formula (I):
^{_{R 1 -C m H 2m - (}} C n H 2n O) p -C q H 2q -R 2 (I)
[Wherein, R ¹ and R ² are each independently a hydrogen atom, OH group, methyl group, glycidyl group or glycidyl ether group, m is 0 to 20, n is 2 to 4, p Is 1-30, q is 0-20, and each carbon atom of the alkylene unit is independently selected from an alkyl group, —OH group, —NH ₂ group, glycidyl group, or glycidyl ether group 1 or May have two substituents]
In this case, mixed alkoxide units may be formed, in which case the order of the alkoxide units is arbitrary.
The concrete admixture according to claim 1.   The admixture for concrete according to claim 2, wherein the hydrophilic compound is a glycidyl ether compound or a glycol compound.   The admixture for concrete according to claim 1, wherein the hydrophilic compound is poly (ethylene glycol) monoethyl-glycidyl ether.   The admixture for concrete according to any one of claims 1 to 4, wherein the lignin is kraft lignin, acetate lignin, organosolv lignin, explosive lignin, sulfate lignin, or alkali lignin.   A method for producing an admixture for concrete comprising a lignin derivative as a main component, wherein lignin and a glycidyl ether compound are reacted under an alkaline condition.   A method for producing an admixture for concrete comprising a lignin derivative as a main component, wherein lignin and a glycol compound are reacted under acidic conditions.   A cement water reducing agent mainly composed of a lignin derivative produced by a reaction between lignin and a hydrophilic compound.