JP2015163571A - Cement additive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement additive which shows enough water reduction performance or can improve holding performance of cement dispersibility with additive quantity less than existing lignin derivatives.SOLUTION: A cement additive contains a lignin derivative in which a lignin part and a polyalkylene glycol part is essential. As for the lignin derivative, the mean addition mole number of alkylene oxide comprising the polyalkylene glycol part is over 10, a mole ratio of the polyalkylene glycol part and the lignin part is 0.1-20, and a number average molecular weight is 6,000-200,000 and molecular weight distribution is 1.0-3.5.

Description

The present invention relates to a cement additive containing a lignin derivative. More specifically, the present invention relates to a cement additive useful for cement compositions such as cement and gypsum and other hydraulic materials.

Lignin is one of the three major components of plant biomass such as wood (three major components: cellulose, hemicellulose, lignin), and is the most abundant on the earth as a natural aromatic polymer. . Regarding the structure of lignin, lignin monomers, which are the three basic skeletons of p-coumalyl alcohol, coniphenyl alcohol, and sinapyrcohol synthesized in photosynthesis, are one-electron oxidized to form phenoxy radicals, which are radically converted into radicals. By coupling, it has a complex three-dimensional network structure.

As described above, the molecular structure of lignin is complex, and the chemical properties of lignin vary greatly depending on the isolation method used for isolation from plant bodies, so the use of lignin as an industrial material is limited. ing. Furthermore, lignin is basically a hydrophobic substance and is poorly water-soluble, which is one reason that its use is limited.

As an example of the use of lignin, the use of an amphiphilic lignin derivative having a hydrophilic group introduced into a hydrophobic lignin as an admixture or a surfactant for concrete is disclosed (for example, Patent Document 1 and Non-Patent Document 1). (See Patent Document 1).

JP 2011-184230 A

Harumi Honma (H HOMA) and 4 others "Journal of Wood Chemistry and Technology" (UK), 2008, 28, p270-282

As described above, it has been sought to impart hydrophilicity to lignin and thereby to develop into water-soluble applications.
However, the amphiphilic lignin derivative does not exhibit performance that can be said to be sufficiently suitable for its use. Therefore, in the cement additive application, which is one of the applications that require hydrophilicity, there is room for improvement to improve the performance of cement water reduction and the like so that the outstanding performance can be exhibited in the application.

The present invention has been made in view of the above-described present situation, and can exhibit sufficient water reduction performance or improve cement dispersibility retention performance even with a small amount of addition than conventional lignin derivatives. An object is to provide a cement additive.

The present inventor paid attention to a lignin derivative having a lignin moiety and a polyalkylene glycol moiety, and affected the performance as a cement additive in combination with the structure of the polyalkylene glycol moiety, the molar ratio of both moieties, the number average molecular weight and the molecular weight distribution. It has been conceived that, by optimizing them, the cement water reduction performance and dispersion retention performance can be improved, and the above-mentioned problems can be solved brilliantly, and the present invention has been achieved.

That is, the present invention is a cement additive comprising a lignin derivative that essentially comprises a lignin moiety and a polyalkylene glycol moiety, wherein the lignin derivative has an average added mole number of alkylene oxide constituting the polyalkylene glycol moiety of 10. A cement additive having a molar ratio of the polyalkylene glycol moiety to the lignin moiety of 0.1 to 20, a number average molecular weight of 6000 to 200,000, and a molecular weight distribution of 1.0 to 3.5. .
The present invention is described in detail below.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

<Lignin derivative>
The lignin derivative of the present invention requires a lignin moiety and a polyalkylene glycol moiety. In addition to these sites, other structural sites may be included.

The lignin site is a structural unit derived from lignin. The lignin is not particularly limited, and examples thereof include alkali lignin, kraft lignin, acetate lignin, organosolv lignin, explosive lignin, sulfate lignin, and the like, and one or more of these lignins can be used. .
Among these lignins, alkaline lignin, acetic acid lignin, organosolv lignin, and explosive lignin are advantageous in that no sulfur odor is generated because no sulfur-containing compound is used for cooking.

The plant used as the raw material for the lignin is not particularly limited. Herbaceous plants and the like.
Among these, woody materials are preferable in terms of dispersion performance, softwoods and hardwoods are more preferable, and coniferous materials are particularly preferable.

The lignin used in the present invention can be obtained by isolating it from the starting material using a commonly used method, for example, the method described in "Lignin Chemistry (Nakano Junzo Hen Uni Uni Publishing)".

The molecular weight of lignin varies depending on the raw material and the isolation method, and the weight average molecular weight of lignin used in the present invention is not particularly limited. For example, lignin having a weight average molecular weight of 500 to 1,000,000 can be used. Preferably, it is a lignin having a weight average molecular weight of 5000 to 100,000. A weight average molecular weight can be measured by the conditions as described in the Example mentioned later using a gel permeation chromatography (GPC) analysis method.

It is preferable that the content rate of the elemental sulfur in the lignin used for the lignin derivative of this invention is the range of 0.1-4 mass% with respect to 100 mass% of lignin. The content of sulfur element is more preferably in the range of 0.1 to 3% by mass. More preferably, it is the range of 0.1-2 mass%, Most preferably, it is the range of 0.1-1 mass%.
The content of sulfur element in lignin can be measured by elemental analysis with the measuring equipment and measurement conditions described in the examples described later.

The polyalkylene glycol moiety in the lignin derivative of the present invention is a structural unit derived from a compound having a polyalkylene glycol chain (hereinafter also referred to as a polyalkylene glycol-containing compound), and is an average of the alkylene oxide constituting the polyalkylene glycol moiety. The added mole number is more than 10.
The average number of moles of alkylene oxide added means the average value of the number of moles of alkylene oxide added in one polyalkylene glycol chain constituting the polyalkylene glycol moiety.
If the average added mole number of the alkylene oxide is 10 or less, the water reducing performance of the cement additive is not sufficient, and the amount of the pure additive of the cement additive necessary for obtaining an appropriate dispersibility of the cement Will increase. The amount added is an indicator of the water reduction performance of the cement additive, and the smaller the amount, the better the water reduction performance. For cement used in a large amount, a great effect will be recognized if the addition amount is slightly reduced.

The average added mole number of the alkylene oxide constituting the polyalkylene glycol moiety is preferably 11 or more, more preferably 13 or more, still more preferably 15 or more, particularly preferably 20 or more, still more preferably 25 or more, and still more preferably. 30 or more, most preferably 50 or more. As an upper limit, the average added mole number of the alkylene oxide is usually preferably 300 or less, more preferably 250 or less, further preferably 200 or less, particularly preferably 150 or less, and still more preferably 100 or less.
Regarding the cement dispersibility retention performance, the average added mole number of the alkylene oxide is preferably 11 or more, more preferably 13 or more, still more preferably 15 or more, particularly preferably 20 or more, and further preferably 25 or more. It is. From the viewpoint of retention performance, the average added mole number of the alkylene oxide is preferably 100 or less, more preferably 75 or less, still more preferably 60 or less, particularly preferably 50 or less, more preferably 40 or less, More preferably, it is 30 or less.

Although it does not specifically limit as said alkylene oxide, It is preferable to use a C2-C18 alkylene oxide, More preferably, it is a C2-C8 alkylene oxide, for example, ethylene oxide, propylene oxide, butylene oxide, Examples include isobutylene oxide, 1-butene oxide, 2-butene oxide, trimethylethylene oxide, tetramethylene oxide, tetramethylethylene oxide, butadiene monooxide, and octylene oxide. In addition, aliphatic epoxides such as dipentane ethylene oxide and dihexane ethylene oxide; alicyclic epoxides such as trimethylene oxide, tetramethylene oxide, tetrahydrofuran, tetrahydropyran, octylene oxide; styrene oxide, 1,1-diphenylethylene oxide, etc. An aromatic epoxide or the like can also be used.

The alkylene oxide constituting the polyalkylene glycol moiety is preferably a relatively short chain alkylene oxide (oxyalkylene group) having about 2 to 8 carbon atoms from the viewpoint of affinity with cement particles. is there. More preferably, the main component is an alkylene oxide having 2 to 4 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide, and still more preferably, the main component is ethylene oxide.

The “main body” as used herein means that when the polyalkylene glycol moiety is composed of two or more kinds of alkylene oxides, it accounts for the majority of the total number of alkylene oxides present. When expressing “dominate” in terms of mol% of ethylene oxide in 100 mol% of all alkylene oxides, 50 to 100 mol% is preferable. Thereby, the lignin derivative of the present invention has higher hydrophilicity. More preferably, it is 60 mol% or more, More preferably, it is 70 mol% or more, Especially preferably, it is 80 mol% or more, Most preferably, it is 90 mol% or more.

The polyalkylene glycol-containing compound is not particularly limited as long as the average number of added moles of alkylene oxide in the polyalkylene glycol moiety is within the above range, but specifically, polyalkylene glycol compounds such as polyethylene glycol and polypropylene glycol (Hereinafter also referred to as glycol compounds); monofunctional glycidyl ether compounds such as polyethylene glycol-monoethyl-glycidyl ether, polyethylene glycol-monomethyl-glycidyl ether, lauryl alcohol-polyethylene oxide-glycidyl ether; poly (ethylene glycol) Bifunctional glycidyl ether compounds such as diglycidyl ether and poly (propylene glycol) diglycidyl ether; and their glycidyl groups The glycidyl ether compound in which the functionality of the glycidyl ether group is lowered by reacting with an alkoxide compound such as methoxy or ethoxy; and an alkoxypolyalkylene glycol such as methoxypolyethylene glycol and epichlorohydrin. And monofunctional epoxy polyalkylene glycol compounds obtained by reaction with epihalohydrins such as
The polyalkylene glycol moiety may be a structure derived from a compound having a polyalkylene glycol chain, and a raw material for constituting such a structure is not specified, but is composed of the above compound. It is preferable. In that case, these compounds have an average addition mole number of alkylene oxide in the compound of more than 10.

The polyalkylene glycol-containing compound is preferably a polyalkylene glycol-containing compound having no unsaturated bond, and more preferably a monofunctional glycidyl ether compound or an alkoxy polyalkylene among polyalkylene glycol-containing compounds having no unsaturated bond. A monofunctional epoxy polyalkylene glycol compound obtained by the reaction of glycol and epihalohydrin, and more preferably a monofunctional epoxy polyalkylene glycol compound obtained by the reaction of alkoxy polyalkylene glycol and epihalohydrin.

The molar ratio of the polyalkylene glycol moiety to the lignin moiety in the lignin derivative of the present invention is 0.1-20. The molar ratio represents the molar ratio of the polyalkylene glycol moiety to 1 mol of the lignin moiety.
When the molar ratio is smaller than the above range, the performance as a cement additive cannot be sufficiently exhibited, and it is not suitable for the application. When it is larger than the above range, the amount of the pure additive of the cement additive necessary for obtaining an appropriate dispersibility of the cement is increased.
The molar ratio between the polyalkylene glycol moiety and the lignin moiety is preferably 1.0 to 13, more preferably 1.5 to 12, still more preferably 2 to 11, and particularly preferably 2. It is 5-10, Most preferably, it is 3-9.
The molar ratio between the polyalkylene glycol moiety and the lignin moiety can be determined by the method described in Examples described later.

The number average molecular weight of the lignin derivative of the present invention is 6,000 to 200,000, preferably 6,000 to 100,000, more preferably 6,000 to 50,000, still more preferably 6,000 to 30,000, and particularly preferably 6,000. ~ 20,000. When the number average molecular weight is out of the above range, it becomes unsuitable for use as a cement additive.
The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the lignin derivative of the present invention is 1.0 to 3.5.
When the molecular weight distribution is smaller than the above range, the molecular weight distribution curve becomes too sharp and it becomes difficult to produce as a cement additive. When it is larger than the above range, the amount of the pure additive of the cement additive necessary for obtaining an appropriate dispersibility of the cement is increased.
The molecular weight distribution of the lignin derivative of the present invention is preferably 1.0 to 2.0, more preferably 1.0 to 1.8, and still more preferably 1.0 to 1.6. The number average molecular weight and molecular weight distribution of the lignin derivative can be measured by the method described in Examples described later using GPC.

<Method for producing lignin derivative>
Although the manufacturing method of the lignin derivative of this invention is not specifically limited, For example, the manufacturing method with which a lignin and a polyalkylene glycol containing compound are made to react is mentioned.
A method for producing such a lignin derivative essentially comprising a lignin moiety and a polyalkylene glycol moiety, wherein the production method includes a step of reacting lignin with a polyalkylene glycol-containing compound. It is also one aspect of the present invention.

In the reaction between the lignin and the polyalkylene glycol-containing compound, for example, the lignin can be derivatized by reacting the hydroxyl group in the lignin with the reactive group of the polyalkylene glycol-containing compound.
The reactive group of the polyalkylene glycol-containing compound is not limited as long as it can react with the hydroxyl group of lignin, and examples thereof include a glycidyl group, a hydroxyl group, a carboxyl group, an aldehyde group, an amino group, and the reactive viewpoint. Therefore, a glycidyl group and a hydroxyl group are preferable.

In the reaction between the lignin and the polyalkylene glycol-containing compound, the amount of the polyalkylene glycol-containing compound added to the lignin depends on the molar ratio between the polyalkylene glycol moiety and the lignin moiety of the lignin derivative of the present invention. Theoretically, since all hydroxyl groups in lignin may react with reactive groups in hydrophilic compounds, the amount of polyalkylene glycol-containing compound added is the amount of hydroxyl groups in lignin, polyalkylene It is calculated based on the amount of the reactive group and the molar ratio in the glycol-containing compound. The addition amount of the polyalkylene glycol-containing compound is usually 5 to 400% by mass, preferably 10 to 300% by mass, and more preferably 15 to 250% by mass with respect to 100% by mass of lignin.

When a glycol-based compound having no glycidyl group is used as the polyalkylene glycol-containing compound, a lignin derivative can be prepared by adding an acid catalyst to a mixture of lignin and a glycol-based compound to cause a reaction. The above-mentioned compounds can be used as the glycol compound.

In the above reaction, hydrochloric acid, sulfuric acid or the like can be used as the acid catalyst. From the viewpoint of improving the yield, as preferable conditions, the addition amount is 0.1 to 3.0% by mass relative to the polyalkylene glycol-containing compound, and the reaction temperature is 100 ° C. to 200 ° C., more preferably 120 ° C. to 160 ° C. The reaction time is 30 minutes to 180 minutes, more preferably 60 minutes to 120 minutes, still more preferably 90 minutes.

In the above 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.

As the polyalkylene glycol-containing compound used in the method for producing a lignin derivative of the present invention, it is preferable to use a glycidyl ether compound from the viewpoint of reactivity.

The above-mentioned compounds can be used as the glycidyl ether compound, but (1) a monofunctional epoxy polyalkylene glycol compound obtained by reacting a bifunctional glycidyl ether compound with an alkoxide compound such as sodium ethoxide. (2) From the viewpoint of reactivity, it is preferable to use a monofunctional epoxy polyalkylene glycol compound obtained by a reaction between an alkoxy polyalkylene glycol and an epihalohydrin such as epichlorohydrin. Examples of the reactions (1) and (2) are shown in the following formulas (1) and (2), respectively. In the formula, n represents a number exceeding 10. R represents an alkyl group having 1 to 12 carbon atoms.

The monofunctional epoxy polyalkylene glycol compound (2) is more preferred as the glycidyl ether compound.
The reaction product of the above (1) includes, as a by-product, a compound having no epoxy group or an unreacted product produced by reacting two glycidyl groups of a bifunctional glycidyl ether compound with two molecules of an alkoxide compound. These bifunctional glycidyl ether compounds are included. When this reaction product and lignin are reacted to synthesize a lignin derivative, the unreacted bifunctional glycidyl ether compound acts as a cross-linking agent, which may increase the molecular weight distribution of the lignin derivative. In the reaction (2), such a side reaction does not occur, and a completely monofunctional epoxy polyalkylene glycol compound can be synthesized, and a lignin derivative having a small molecular weight distribution can be synthesized.

As the alkoxypolyalkylene glycol used in the reaction (2), the above-mentioned compounds can be used, and methoxypolyethylene glycol is preferable.
As the epihalohydrin, the above-mentioned compounds can be used, and epichlorohydrin is preferable from the viewpoint of improving the yield.

The addition amount of epihalohydrin used in the reaction (2) is not particularly limited, but is preferably 100 to 1000 mol%, more preferably 300 to 800 mol% with respect to 100 mol% of the alkoxypolyalkylene glycol.

In the reaction (2), as the base, alkali metal or alkaline earth metal hydroxide, alkali metal or alkaline earth metal hydride, or the like can be used. Specifically, examples of the alkali metal include lithium, sodium, and potassium, and examples of the alkaline earth metal include beryllium, magnesium, and calcium. The base is preferably sodium hydride from the viewpoint of reactivity, and the addition amount is preferably 80 to 150 mol% with respect to 100 mol% of the alkoxypolyalkylene glycol.
Furthermore, as a solvent, the organic solvent used for a general synthesis | combination can be used, Preferably they are acetonitrile, a dimethylformamide, a dioxane, and tetrahydrofuran.
As preferable conditions for the reaction (2) above, the reaction temperature is 50 ° C. to 150 ° C., more preferably 50 ° C. to 80 ° C., and the reaction time is 60 minutes to 600 minutes, more preferably 180 minutes to 360 minutes. .

The reaction between the hydroxyl group of the lignin and the epoxy group of the glycidyl ether compound can be performed by a commonly used method.
For example, a lignin derivative can be prepared by dissolving lignin in an aqueous alkaline solution and reacting a hydroxyl group (lignin-OH) in lignin liberated under alkaline conditions with an epoxy group in a glycidyl ether compound. Obtained after alkaline digestion of lignocellulosic biomass.
Black liquor can also be used as the alkaline aqueous solution of lignin.

As reaction conditions for the hydroxyl group of the lignin and the epoxy group of the glycidyl ether compound, the reaction temperature is usually 50 ° C. to 100 ° C., preferably 70 ° C., and the reaction time is usually 30 minutes to 24 hours, preferably 1 Time to 12 hours, more preferably 2 hours to 6 hours.

In the above reaction, it is preferable to neutralize the reaction system by adding an acid after completion of the reaction between lignin and the glycidyl ether compound. 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.

The above reaction is completed when the resulting lignin derivative becomes hydrophilic due to the introduction of the polyalkylene glycol chain of the glycidyl ether compound into the hydrophobic lignin. Completion of the reaction between the lignin and the glycidyl ether 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 a part 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.
Hereinafter, the lignin derivative of the present invention is also referred to as an amphiphilic lignin derivative.

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.

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.

As an example of the reaction between the lignin and the glycidyl ether compound, a preferred reaction form is shown in the following formula (3). In the formula, n represents a number exceeding 10. R represents an alkyl group having 1 to 12 carbon atoms.

<Cement additive>
When the lignin derivative of the present invention is used as a cement additive, it may be used in the form of an aqueous solution or may be used after pulverized. When drying, you may dry completely by conventionally used drying methods, such as a freeze dryer. In addition, the powdered cement additive 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, etc. Alternatively, it may be blended when the cement composition is kneaded.

Preferably, the cement additive 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 blending amount of the cement additive of the present invention when added to cement is arbitrary, but for example, 0.01 to 10.0% by mass, preferably 0.0. It is 02-5.0 mass%, More preferably, it is 0.1-1.0 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, fluidity is remarkably imparted, and therefore, the effect as a so-called cement water reducing agent is excellent, which is preferable.

The cement additive of the present invention can also be used in combination with other cement additives, and can also be used in combination with a polycarboxylic acid-based water reducing agent. The polycarboxylic acid-based water reducing agent may be any water reducing agent including a polymer having a (poly) alkylene glycol chain in the side chain of a polycarboxylic acid such as poly (meth) acrylic acid.
Examples of the unsaturated carboxylic acid monomer constituting the polycarboxylic acid include monocarboxylic acid monomers such as acrylic acid, methacrylic acid, and crotonic acid; maleic acid, itaconic acid, fumaric acid, citraconic acid, and the like. These dicarboxylic acid monomers, their dicarboxylic acid anhydrides, and their salts.
Although it does not specifically limit as said (poly) alkylene glycol chain | strand, It is preferable that it is a polymer chain ((poly) alkylene oxide) comprised from the above-mentioned alkylene oxide.
The characteristics of the polycarboxylic acid-based water reducing agent are not particularly limited as long as they can be used in combination with the cement additive of the present invention to improve dispersibility and exhibit water reducing performance.
The polycarboxylic acid water reducing agent may be used alone or in combination of two or more.

The cement additive of the present invention can also be used in combination with an oxycarboxylic acid compound. By using the oxycarboxylic acid compound in combination, higher dispersion retention performance can be exhibited even in a high temperature environment. As the oxycarboxylic acid compound, an oxycarboxylic acid having 4 to 10 carbon atoms or a salt thereof is preferable, and specifically, for example, gluconic acid, glucoheptonic acid, alabonic acid, malic acid, citric acid, and sodium thereof. Inorganic salts or organic salts such as potassium, calcium, magnesium, ammonium and triethanolamine. These oxycarboxylic acid compounds may be used alone or in combination of two or more. Of these oxycarboxylic acid compounds, gluconic acid or a salt thereof is particularly suitable. In particular, in the case of poor blended concrete, a lignin sulfonate-based dispersant is used as a sulfonic acid-based dispersant having a sulfonic acid group in the molecule, and gluconic acid or a salt thereof is used as an oxycarboxylic acid-based compound. It is preferable.
The cement additive of the present invention can also be used in combination with other cement additives as described in JP2013-53010A as other cement additives.

Other cement additives that can be used in combination with the cement additive of the present invention include water-soluble polymer materials, polymer emulsions, retarders, early strengthening agents / accelerators, mineral oil-based antifoaming agents, fats and oils Antifoaming agent, fatty acid-based antifoaming agent, fatty acid ester-based antifoaming agent, oxyalkylene-based antifoaming agent, alcohol-based antifoaming agent, amide-based antifoaming agent, phosphate ester-based antifoaming agent, metal soap-based defoaming agent Agents, silicone-based antifoaming agents, AE agents, other surfactants, waterproofing agents, rust-preventing agents, crack reducing agents, expansion materials, and the like, and these are the same as those described in JP 2012-131997 A Can be used.

Other cement additives (materials) include, for example, cement wetting agents, thickeners, separation reducing agents, flocculants, drying shrinkage reducing agents, strength enhancers, self-leveling agents, coloring agents, fungicides, blast furnace slag, Examples include fly ash, cinder ash, clinker ash, husk ash, silica fume, silica powder, and gypsum.

The blending ratio when used in combination with the cement additive of the present invention and other cement additives is the mass of the solid content of the lignin derivative, which is an essential component of the cement additive of the present invention, and the solid content of other cement additives. The ratio is preferably 1 to 99 / 99-1. More preferably, it is 5-95 / 95-5, More preferably, it is 10-90 / 90-10, Most preferably, it is 20-80 / 80-20.
Further, when using the cement additive of the present invention and a polycarboxylic acid-based water reducing agent or oxycarboxylic acid-based compound and another cement additive, lignin and polycarboxylic acid-based water reducing water which are essential components of the cement additive of the present invention. The mass ratio of the agent or the oxycarboxylic acid compound and the other cement additive is preferably 1 to 98/1 to 98/1 to 98. More preferably, it is 5-90 / 5-90 / 5-90, More preferably, it is 10-90 / 5-85 / 5-85, Most preferably, it is 20-80 / 10-70 / 10-10 70.

Among the various other cement additives described above, as a cement additive used in combination with the cement additive of the present invention, in addition to a polycarboxylic acid-based water reducing agent and an oxycarboxylic acid-based compound, an oxyalkylene-based antifoaming agent, An accelerator, a separation reducing agent, and an AE agent are preferable. When an AE agent is used, it is preferable to use the three components of the cement additive of the present invention, an oxyalkylene antifoaming agent, and an AE agent.

Among the above, polyoxyalkylene alkylamines are preferable as the oxyalkylene-based antifoaming agent used in combination with the cement additive of the present invention.
When the cement additive of the present invention and the oxyalkylene antifoaming agent are used in combination, the blending ratio of the oxyalkylene antifoaming agent is based on the solid content of the lignin derivative that is an essential component of the cement additive of the present invention. It is preferable that it is 0.01-20 mass%.
In addition, when the three components of the cement additive of the present invention, the oxyalkylene antifoaming agent and the AE agent are used in combination, the proportion of the oxyalkylene antifoaming agent is the same as described above, and the proportion of the AE agent is It is preferable that it is 0.001-2 mass% with respect to the mass of the solid content of the lignin derivative which is an essential component of the cement additive of the invention.

When the cement additive of the present invention and the accelerator are used in combination, the mass ratio of the lignin derivative, which is an essential component of the cement additive of the present invention, and the accelerator is 10/90 to 99.9 / 0.1. It is preferable. More preferably, it is 20/80 to 99/1.

When the cement additive of the present invention and the separation reducing agent are used in combination, the separation reducing agent includes various thickening agents such as nonionic cellulose ethers, and a hydrocarbon chain having 4 to 30 carbon atoms as a partial structure. 1 type (s) or 2 or more types, such as a compound which has a hydrophobic substituent and the polyoxyalkylene chain which added the C2-C18 alkylene oxide by the average addition mole number 2-300, can be used.
When the cement additive of the present invention and the separation reducing agent are used in combination, the mass ratio of lignin, which is an essential component of the cement additive of the present invention, and the separation reducing agent is 10/90 to 99.99 / 0.01. Preferably there is. More preferably, it is 50 / 50-99.9 / 0.1. The cement composition containing the cement additive of the present invention and the separation reducing agent can be suitably used as high-fluidity concrete, self-filling concrete, and self-leveling material.

The cement additive of the present invention can be used in addition to a cement composition such as cement paste, mortar, concrete, etc., and such a cement composition comprising the cement additive of the present invention is also one of the present inventions. One.

As the above-mentioned cement composition, those containing cement, water, fine aggregate, coarse aggregate and the like are suitable, and the cement is not particularly limited. For example, Portland cement (ordinary, early strength, very early strength, And the like, and those similar to those described in JP-A No. 2009-046655 can be used. As the above aggregate, in addition to gravel, crushed stone, granulated slag, recycled aggregate, etc., siliceous, clay, zircon, high alumina, silicon carbide, graphite, chrome, chromic, magnesia, etc. Refractory aggregate and the like.

Examples of the unit water amount per 1 m ³ of the cement composition, the cement use amount, and the water / cement ratio (mass ratio) include, for example, a unit water amount of 100 to 185 kg / m ³ , a use cement amount of 200 to 800 kg / m ³ , and a water / cement ratio. The cement ratio (mass ratio) is preferably 0.1 to 0.7, and more preferably, the unit water amount is 120 to 175 kg / m ³ , the cement amount used is 250 to 800 kg / m ³ , and the water / cement ratio ( (Mass ratio) = 0.2 to 0.65. Thus, the cement admixture containing the multi-branched polyalkylene glycol block copolymer of the present invention can be used in a wide range from poor blending to rich blending, and has a high water reduction rate range, that is, water / Cement ratio (mass ratio) = 0.15 to 0.5 (preferably 0.15 to 0.4) can be used even in a region where the water / cement ratio is low. Is effective for both high-strength concrete with a small amount and poor blend concrete with a unit cement amount of 300 kg / m ³ or less.

The cement additive of the present invention is a cement additive that has the above-described configuration, exhibits excellent water reduction performance as compared with conventional lignin derivatives, and can make the cement composition excellent in fluidity.

It is the figure which showed the example of the GPC RI chart in calculation of the reaction rate of a polyalkylene glycol containing compound. It is the figure which showed the relationship between the pure amount conversion addition amount of the lignin derivative (cement additive) of Examples 2, 6, and 9 and Comparative Examples 1, 5, and 6, and the 0 striking flow value. It is the figure which showed the relationship between the elapsed time after the kneading | mixing of Example 2 and Comparative Example 7, and a slump flow value.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

<GPC measurement conditions>
Apparatus: Waters Alliance (2695), manufactured by Waters
Analysis software: Waters, Empor professional + GPC option column: Tosoh TSKguard column α
・ TSKgel α-3000
・ TSKgel α-4000
・ TSKgel α-5000
Detector: differential refractometer (RI) detector (Waters 2414, manufactured by Waters)
Eluent: Standard substance for preparing a solvent calibration curve in which 96 g of 50 mM aqueous sodium hydroxide solution and 3600 g of acetonitrile were mixed in 14304 g of 100 mM boric acid aqueous solution: polyethylene glycol [peak top molecular weight (Mp) 300000, 200000, 107000, 50000, 27700, 11840, 6450, 1470, 1010, 400]
Calibration curve: Created by cubic equation based on Mp value and elution time of polyethylene glycol Flow rate: 1.0 mL / min
Column temperature: 40 ° C
Measurement time: 60 minutes Sample solution injection amount: 100 μL (eluent preparation solution with sample concentration of 0.5 wt%)

<Sulfur element content>
The sulfur element content of lignin was measured by the following measurement method.
Measuring instrument: vario EL cube (manufactured by Elemental, CHNSO fully automatic elemental analyzer)
Measurement condition:
Measurement mode CHNS
Combustion tube set temperature 1150 ° C, reduction tube set temperature 850 ° C
Combustion tube filler: Tungsten oxide reducing tube filler: Reduced copper measurement gas flow meter: MFC-TCD about 230 ml / min
Helium gas flow meter: Fiow He 230ml / min
Sample amount: about 2 mg, tin boat enveloping detector: TCD

<Cooking conditions>
Cooking was performed under the following conditions to obtain a black liquor containing lignin.
Wood: Cryptomeria japonica cooking temperature: 170 ° C, cooking time: 2h
Active alkali (sodium hydroxide) addition rate (converted to active alkali (sodium oxide)): 19.5% (ratio to wood)
AQ (anthraquinone) addition rate: 0.1% (ratio to wood)
Liquid ratio: 5L / kg
Pulp yield: 44%
Residual lignin content in the pulp: 2.8%

<Purification of lignin>
About 30% sulfuric acid aqueous solution was added to the black liquor which is a strong alkaline aqueous solution obtained by the above cooking, and the pH was adjusted to 2.0 while stirring to cause precipitation. The precipitate was collected by centrifugation and washed with distilled water. The precipitate was collected by filtration or centrifugation, dried in air, and then dried under reduced pressure. The dried product was lightly pulverized in a mortar to obtain purified lignin. The number average molecular weight (Mn) of the purified lignin was 12600, and the weight average molecular weight (Mw) was 16000. The content of elemental sulfur in the purified lignin was 0.2% by mass with respect to 100% by mass of the purified lignin.

<Production Example 1: Monofunctional Epoxy PEG (25 mol)>
A glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube was charged with 50.0 parts of tetrahydrofuran and 2.0 parts of sodium hydride having a concentration of 60%.
50.0 parts of tetrahydrofuran was added to 50.0 parts of methoxypolyethylene glycol (also referred to as methoxy PEG (25 moles)) having an average addition mole number of ethylene oxide of 25, and the mixture was sufficiently homogenized and then cooled in an ice-cooled reaction vessel. Added to. Thereafter, the mixture was stirred for 10 minutes.
Next, 16.4 parts of epichlorohydrin was added while cooling the reaction vessel with ice, and the reaction vessel was heated to 70 ° C. The heating was stopped within 5 hours from the start of heating, and the reaction was completed. The reaction vessel was ice-cooled and 1.5 parts of water was added to deactivate unreacted sodium hydride.
In order to concentrate the obtained reaction product, tetrahydrofuran and unreacted epichlorohydrin were distilled off by an evaporator.
The concentrated solution of the obtained reaction product was slowly added dropwise to 400.0 parts of diethyl ether, and the resulting precipitate was filtered under reduced pressure and dried at room temperature, whereby the lignin derivatives of Examples 1 to 4 and Comparative Example 5 were used. Monofunctional epoxy PEG used in the production of was obtained.

<Production Example 2: Monofunctional epoxy PEG (50 mol)>
A glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube was charged with 10.0 parts of tetrahydrofuran and 1.0 part of sodium hydride having a concentration of 60%.
100.0 parts of tetrahydrofuran was added to 50.0 parts of methoxypolyethylene glycol (also referred to as methoxy PEG (50 moles)) having an average addition mole number of ethylene oxide of 50, and the mixture was sufficiently homogenized and then ice-cooled in a reaction vessel. Added to. Thereafter, the mixture was stirred for 10 minutes.
Next, 7.0 parts of epichlorohydrin was added while cooling the reaction vessel with ice, and the reaction vessel was heated to 70 ° C. The heating was stopped within 5 hours from the start of heating, and the reaction was completed. The reaction vessel was ice-cooled, 0.8 parts of water was added, and unreacted sodium hydride was deactivated.
In order to concentrate the obtained reaction product, tetrahydrofuran and unreacted epichlorohydrin were distilled off by an evaporator.
The obtained concentrate of the reaction product is slowly added dropwise to 400.0 parts of diethyl ether, and the resulting precipitate is filtered under reduced pressure and dried at room temperature to be used for producing the lignin derivatives of Examples 5 to 10. Monofunctional epoxy PEG was obtained.

<Production Example 3: Monofunctional Epoxy PEG (10 mol)>
A glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube was charged with 60.0 parts of tetrahydrofuran and 5.1 parts of sodium hydride having a concentration of 60%.
60.0 parts of tetrahydrofuran was added to 60.0 parts of methoxypolyethylene glycol (also referred to as methoxy PEG (10 moles)) having an average addition mole number of ethylene oxide of 10, and the mixture was sufficiently homogenized and then cooled in an ice-cooled reaction vessel. Added to. Thereafter, the mixture was stirred for 10 minutes.
Next, 38.4 parts of epichlorohydrin was added while cooling the reaction vessel with ice, and the reaction vessel was heated to 70 ° C. The heating was stopped within 5 hours from the start of heating, and the reaction was completed. The reaction vessel was ice-cooled and 3.9 parts of water was added to deactivate unreacted sodium hydride.
In order to concentrate the obtained reaction product, tetrahydrofuran and unreacted epichlorohydrin were distilled off by an evaporator.
The obtained concentrate of the reaction product is slowly added dropwise to 400.0 parts of diethyl ether, and the resulting precipitate is filtered under reduced pressure and dried at room temperature to be used for producing the lignin derivatives of Comparative Examples 1 to 4. Monofunctional epoxy PEG was obtained.

<Production Example 4: Monofunctional epoxy PEG (90 mol)>
A glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube was charged with 10.0 parts of tetrahydrofuran and 1.0 part of sodium hydride having a concentration of 60%.
180.0 parts of tetrahydrofuran was added to 90.0 parts of methoxypolyethylene glycol (methoxyPEG (90 moles)) having an average addition mole number of ethylene oxide of 90, and the mixture was sufficiently homogenized and then added to an ice-cooled reaction vessel. . Thereafter, the mixture was stirred for 10 minutes.
Next, 7.0 parts of epichlorohydrin was added while cooling the reaction vessel with ice, and the reaction vessel was heated to 70 ° C. The heating was stopped within 5 hours from the start of heating, and the reaction was completed. The reaction vessel was ice-cooled, 0.8 parts of water was added, and unreacted sodium hydride was deactivated.
The resulting reaction solution was centrifuged to remove the produced salt.
The reaction solution from which the salt had been removed was slowly added dropwise to 720.0 parts of diethyl ether, and the resulting precipitate was filtered under reduced pressure and dried at room temperature, whereby the monofunctional compound used in the production of the lignin derivatives of Examples 11 and 12 was used. A type epoxy PEG was obtained.

<Production of lignin derivative of Example 1>
In a glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube, 32.7 parts of purified lignin and 4.9 parts of monofunctional epoxy PEG obtained in Production Example 1 were added to 151.2 parts of a 20% sodium hydroxide solution. Dissolved in. The container was heated to 70 ° C. and reacted for 3 hours to obtain the amphiphilic lignin derivative of Example 1.
From the GPC measurement result of the obtained sample, the reaction rate of the monofunctional epoxy PEG of the amphiphilic lignin derivative of Example 1 was 99.0%, and the amphiphilic property of Example 1 in the sample solid content was The pure concentration of the lignin derivative was 50.8%.

The lignin derivatives of Examples 2 to 4 and Comparative Example 5 used the monofunctional epoxy PEG obtained in Production Example 1, and the lignin derivatives of Examples 5 to 10 were the monofunctional epoxy obtained in Production Example 2. Using PEG, the lignin derivatives of Comparative Examples 1 to 4 were produced with the same formulation as in Example 1 using the monofunctional epoxy PEG obtained in Production Example 3. The amount of each raw material charged is as shown in Table 1. In Table 1, the monofunctional epoxy PEG is indicated as EPEG.

<Example 11: Lignin derivative 11>
In a glass reaction vessel equipped with a thermometer, stirrer, and reflux tube, 18.6 parts of purified lignin (solid content 92.6%, pure lignin content 88.0%) was added 30.3 parts of 2M aqueous sodium hydroxide solution (NaOH). 2.4 parts) and 15.7 parts of monofunctional epoxy PEG (hereinafter also referred to as EPEG) obtained in Production Example 4 were added. The container was heated to 70 ° C. and reacted for 3 hours to obtain amphiphilic lignin 11. From the GPC measurement result of the obtained sample, the reaction rate of the monofunctional epoxy PEG of the amphiphilic lignin of Example 11 is 85%, and the pure content concentration of the amphiphilic lignin in the sample solid content is 82%. Met. Furthermore, the mass ratio of the structural site derived from lignin to the structural site derived from EPEG in amphiphilic lignin 11 was 49:51. The mass ratio between the structural site derived from lignin and the structural site derived from EPEG was determined by the calculation method described later.

<Example 12: Lignin derivative 12>
In a glass reaction vessel equipped with a thermometer, a stirrer, and a reflux tube, 13.5 parts of purified lignin (solid content 92.6%, lignin pure content 88.0%) was added 22.0 parts of 2M aqueous sodium hydroxide solution (NaOH). 1.8 parts) and 55.0 parts of distilled water, and 23.2 parts of monofunctional epoxy PEG (hereinafter also referred to as EPEG) obtained in Production Example 4 was added. The container was heated to 70 ° C. and reacted for 3 hours to obtain amphiphilic lignin 12. From the GPC measurement result of the obtained sample, the reaction rate of the monofunctional epoxy PEG of the amphiphilic lignin of Example 12 was 90%, and the pure content concentration of the amphiphilic lignin in the sample solid content was 86%. Met. Furthermore, the mass ratio of the structural site derived from lignin to the structural site derived from EPEG in amphiphilic lignin 12 was 35:65. The mass ratio between the structural site derived from lignin and the structural site derived from EPEG was determined by the calculation method described later.

<Production of lignin derivative of Comparative Example 6>
(Preparation of glycidyl ether compounds)
24 parts of polyethylene glycol diglycidyl ether (Nagase ChemteX Corp., Denacol EX-841) having an average addition mole number of ethylene oxide of 13 was added to 20 parts of acetone and heated to 50 ° C. with stirring. Next, 1.36 parts of sodium ethoxide was dissolved in 12 parts of ethanol and heated to 50 ° C. The sodium ethoxide solution was added dropwise to the glycidyl ether compound acetone solution heated to 50 ° C. over 20 minutes, 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)
33.3 parts of the monofunctional glycidyl ether compound prepared by the above method was added to 18.0 parts of the above-mentioned alkaline lignin 1N sodium hydroxide aqueous 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, and the lignin derivative of Comparative Example 6 was obtained.

<Molar ratio of polyalkylene glycol moiety and lignin moiety>
The molar ratio of the polyalkylene glycol moiety to the lignin moiety in the lignin derivative is based on the following formula (4), and the lignin and polyalkylene glycol (hereinafter referred to as PAG) relative to 100% by mass of the purified lignin and the polyalkylene glycol-containing compound as raw materials. The composition ratio (mass%) of the finished lignin and PAG is obtained from the preparation ratio (mass%) of the contained compound (hereinafter also referred to as the composition ratio) and the reaction rate (%). %) Can be obtained by converting the molar ratio. The reaction rate of purified lignin is 100%.

<Calculation of PAG reaction rate>
The PAG reaction rate can be calculated using the numerical values of (a) to (c) based on the following formula (5). FIG. 1 shows an example of a GPC RI chart. In the figure, the difference in area between (1) and (2) corresponds to the amount of reacted PAG.
(A) Charge weight of various raw materials (b) Area ratio in 10-25 minutes with respect to 100% area up to 10-32 minutes in GPC RI chart of raw material lignin (c) In GPC RI chart of amphiphilic lignin derivative In the GPC RI chart of FIG. 1, the area where the area is 0 is omitted, and the elution time is shown from 15 minutes.
As a method for measuring the reaction rate of PAG, in addition to the method of calculating from the RI area ratio of GPC, the number of phenolic hydroxyl groups in lignin was measured before and after the reaction with an ultraviolet-visible spectrophotometer. In this application, the GPC method is used for measurement.

Charge composition (mass%) of lignin and PAG of Examples 1-12 and Comparative Examples 1-6, PAG reaction rate, finished composition (mass% and molar ratio) of lignin and PAG, pure content, number average molecular weight, weight average The molecular weight and molecular weight distribution are shown in Table 2. In Examples and Comparative Examples, since epoxy polyethylene glycol is used as PAG, PAG is represented as EPEG in Table 2.

<Mortar test>
Mortar was prepared as follows, and the initial mortar air amount (hereinafter also simply referred to as air amount) and zero-stroke flow value were measured. The results are shown in Tables 3 and 4. Moreover, what graphed a part of result of Table 3 and 4 is shown in FIG.
In the mortar test, MA-404 (manufactured by BASF Pozzolith Co., Ltd.) was used as an antifoaming agent, and an amount of 25% by mass to each component solid content was added to each component.

<Mortar flow test>
The mortar flow test was performed in an environment where the temperature was 20 ° C. ± 1 ° C. and the relative humidity was 60% ± 10%.
The mortar formulation was C / S / W = 500/1350/250 (g).
However,
C: Ordinary Portland cement (manufactured by Taiheiyo Cement)
S: Standard sand for cement strength test (Cement Association)
W: As the samples of Examples 1 to 12, Comparative Examples 1 to 6, and the ion exchange aqueous solution W of the antifoaming agent, each component of the addition amount shown in Tables 3 and 4 was weighed out, and the antifoaming agent MA-404. Was added in an amount of 25% by mass to the solid content of each component, and ion-exchanged water was further added to obtain a predetermined amount, which was sufficiently uniformly dissolved. In Tables 3 and 4, the amount of each component added is represented by mass% of the solid content of each component with respect to the cement mass.

<Preparation of mortar>
A stainless beater (stirring blade) was attached to a Hobart mortar mixer (model number N-50; manufactured by Hobart), C and W were added, and kneaded at a first speed for 30 seconds. Further, S was added over 30 seconds while kneading at a first speed. After the completion of S addition, after kneading for 30 seconds at the second speed, the mixer was stopped, the mortar was scraped off for 15 seconds, and then allowed to stand for 75 seconds. The mixture was allowed to stand for 75 seconds and then kneaded at a second speed for 60 seconds to prepare a mortar.

<0-stroke flow value measurement>
The mortar was transferred from the kneading container to a polyethylene 1 L container, stirred for 20 times with a spatula, and immediately placed on a flow measuring plate (30 cm × 30 cm) (micro concrete slump cone, described in JIS-A-1173). (Upper end inner diameter 50mm, lower end inner diameter 100mm, height 150mm) Packed in half of the flow cone (described in JIS-R-5201 (revised in 1997)) and pushed with a stick with 15 turns, and further packed the mortar to the full size of the flow cone. I struck with a stick with 15 strokes and finally made up the shortage and smoothed the surface of the mini slump cone. Immediately after that, the flow cone is pulled up vertically, and the diameter of the expanded mortar (the diameter of the longest part (major axis) and the diameter of the part forming 90 degrees with respect to the major axis) is measured in two places, and the average value is zero. The flow value was used.
In addition, the zero stroke flow value has a better dispersion performance as the numerical value is larger.

<Calculation of addition amount required for proper flow 220 mm>
Based on the data obtained from the mortar evaluation, the pure equivalent added amount and the flow value are plotted, and the pure equivalent added amount necessary to reach the appropriate flow value of 220 mm is calculated. It was shown to. It was confirmed that the cement additives using the lignin derivatives of Examples 1 to 12 exhibited a high cement dispersing effect with a smaller amount of use than the cement additives using the lignin derivatives of Comparative Examples 1 to 6. It was.

<Concrete test>
Using the cement additive obtained in Example 2 and commercially available lignin sulfonic acid (Pozoris No. 8, manufactured by BASF Pozoris) as Comparative Example 7, the additive addition amount and kneading for obtaining a predetermined slump flow value Immediately after that, the slump flow value and the air amount after 20 minutes, 40 minutes and 60 minutes of kneading were evaluated, and the results are shown in Table 6 and FIG. It was confirmed that the cement additive using the lignin derivative of Example 2 exhibited higher dispersion retention performance than the cement additive of Comparative Example 7.

The test conditions of the concrete test are shown below.
<Combination in concrete composition>
Unit cement amount: 366.0 kg / m ³
Unit water amount: 174 kg / m ³ (including additives such as additives and antifoaming agents)
Unit fine aggregate amount: 790.0 Kg / m ³
Unit coarse aggregate amount: 968 kg / m ³
Water / cement ratio (W / C): 47.5%
Aggregate amount ratio (s / a): 45.0%
Cement: Taiheiyo Cement, Ordinary Portland cement Fine aggregate: Oigawa river sand, Kimitsu mountain sand coarse aggregate: Ome crushed stone

<Preparation of concrete composition>
Each material was weighed so that the amount of kneading became 30 L depending on the above concrete raw materials and blending, and the materials were kneaded by the method described below using a bread mixer.
First, fine aggregate, coarse aggregate and cement were kneaded for 10 seconds, and then a predetermined amount of tap water containing a cement admixture was added and kneaded for 90 seconds to obtain a concrete composition.

<Preparation of cement additive>
Prepared using polymer and antifoam. A predetermined amount of an aqueous solution of lignin derivative is weighed, and a commercially available oxyalkylene-based antifoaming agent (manufactured by BASF Pozzolith Co., Ltd., Micro Air 404) is used as the antifoaming agent so that the air amount becomes 3 to 6% (volume%). Adjusted.

<Measurement method of slump flow value and mortar air volume>
The slump flow value was measured by the method of JIS-A-1101 (revised in 2005).
The mortar air amount (initial air amount) was measured by the method of JIS-A-1128 (revised in 2005). About 200 mL of mortar was packed in a 500 mL glass graduated cylinder, struck with a round bar having a diameter of 8 mm, and gently bubbled by hand to remove coarse bubbles. Further, about 200 mL of mortar was added and air bubbles were similarly removed. Then, the volume and mass of the mortar were measured, and the amount of air was calculated from the density of each material.

<Drying shrinkage reduction performance test>
The dry shrinkage reduction performance of the cement additives obtained in Examples 2 and 4 and the commercially available lignin sulfonic acid (Pozoris No. 8, manufactured by BASF Pozoris) as Comparative Example 7 were evaluated. About the concrete composition obtained by the above concrete test method, a specimen was prepared by the method of JIS-A-1132, and the specimen was stored for a certain period of time by the method of JIS-A-1129 (2009 revision). The change in length was measured. The above specimens were stored at 20 ± 2 ° C. and humidity 60 ± 5%, and Table 7 shows the rate of change in the length of the specimens after storage for 8 weeks with respect to the specimen length of 100% at the start of storage.
When Examples 2 and 4 were used, the rate of change in length was lower than that of Comparative Example 7 which was a commercially available lignin sulfonic acid (Posolis No. 8 manufactured by BASF Pozzolith Co., Ltd.), and drying shrinkage reduction was confirmed. It was done.

Claims (4)

A cement additive comprising a lignin derivative that essentially comprises a lignin moiety and a polyalkylene glycol moiety,
In the lignin derivative, the average number of added moles of the alkylene oxide constituting the polyalkylene glycol moiety exceeds 10, the molar ratio of the polyalkylene glycol moiety to the lignin moiety is 0.1 to 20, and the number average molecular weight is A cement additive having a molecular weight distribution of 6000 to 200,000 and a molecular weight distribution of 1.0 to 3.5. The cement additive according to claim 1, wherein the average added mole number of alkylene oxide constituting the polyalkylene glycol moiety is 30 or more. The cement additive according to claim 1 or 2, wherein a molar ratio between the polyalkylene glycol moiety and the lignin moiety is 1.0 to 13. The cement additive according to any one of claims 1 to 3, wherein the lignin derivative has a molecular weight distribution of 1.0 to 2.0.

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