Polysaccharide derivatives and hydraulic compositions

A polysaccharide derivative prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative by (A) a hydrophobic substituent having a C.sub.8 -C.sub.43 hydrocarbon chain as the partial structure and (B) an ionic hydrophilic substituent having at least one member selected from the group consisting of sulfonic, carboxyl phosphoric, and sulfate groups and salts thereof as the partial structure, wherein the average degree of replacement by the substituent (A) is 0.0001 or above but below 0.001 per constituent monosaccharide residue as determined by Zeisel's method or the diazomethane method and that by the substituent (B) is 0.01 to 2.0 per constituent monosaccharide residue as determined by colloidal titration. This polysaccharide derivative is useful as the admixture for hydraulic materials and can give stable hydraulic compositions excellent in dispersion.

 

We claim:

1. A polysaccharide derivative prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative with (A) a hydrophobic substituent having a C.sub.8 -C.sub.43 hydrocarbon chain and (B) an ionic hydrophilic substituent having at least one member selected from the group consisting of sulfonic, carboxyl, phosphoric, and sulfate groups and salts thereof, wherein the average degree of replacement by the substituent (A) is 0.0001 or above but below 0.001 per monosaccharide unit as determined by Zeisel's method or the diazomethane method, and by the substituent (B) is 0.01 to 2.0 per monosaccharide unit as determined by colloidal titration.

2. The polysaccharide derivative according to claim 1, wherein the polysaccharide or polysaccharide derivative is one selected from the group consisting of cellulose, guar gum, starch, hydroxyethylcellulose, hydroxyethyl guar gum, hydroxyethylstarch, methylcellulose, methyl guar gum, methylstarch, ethylcellulose, ethyl guar gum, ethylstarch, hydroxypropylcellulose, hydroxypropyl guar gum, hydroxypropylstarch, hydroxyethylmethylcellulose, hydroxyethylmethyl guar gum, hydroxyethylmethylstarch, hydroxypropylmethylcellulose, hydroxypropylmethyl guar gum and hydroxypropylmethylstarch.

3. The polysaccharide derivative according to claim 1, wherein the substituent (A) is a C.sub.10 -C.sub.43 linear or branched alkyl, alkenyl or acyl group which may be hydroxylated or interrupted by oxycarbonyl group (--COO-- or --OCO--) or an ether linkage and the substituent (B) is an optionally hydroxylated C.sub.1 -C.sub.5 sulfoalkyl group or a salt thereof.

4. The polysaccharide derivative according to claim 3, wherein the substituent (A) is at least one selected from the group consisting of C.sub.12 -C.sub.36 linear and branched alkyl, alkenyl and acyl groups which may be hydroxylated or interrupted by an ether linkage, and the substituent (B) is at least one selected from the group consisting of 2-sulfoethyl, 3-sulfopropyl, 3-sulfo-2-hydroxypropyl and 2-sulfo-1-(hydroxymethyl)ethyl.

5. A hydraulic composition comprising a hydraulic material and 0.1 to 5% by weight based on the hydraulic material of a polysaccharide derivative prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative with (A) a hydrophobic substituent having a C.sub.8 -C.sub.43 hydrocarbon chain and (B) an ionic hydrophilic substituent having at least one member selected from the group consisting of sulfonic, carboxylic, phosphoric, and sulfate groups and salts thereof.

6. The hydraulic composition according to claim 5, wherein the substituent (A) is a C.sub.10 -C.sub.43 linear or branched alkyl, alkenyl or acyl group which may be hydroxylated or interrupted by oxycarbonyl (--COO-- or --OCO--) or an ether linkage; the substituent (B) is an optionally hydroxylated C.sub.l -C.sub.5 sulfoalkyl group or a salt thereof; the average degree of replacement by the substituent (A) is 0.0001 or above but below 0.001 per monosaccharide unit as determined by Zeisel's method or the diazomethane method; and that by the substituent (B) is 0.01 to 2.0 per monosaccharide unit as determined by colloidal titration.

7. The hydraulic composition according to claim 5, wherein the polysaccharide derivative is an alkylated or hydroxyalkylated polysaccharide; the hydrocarbon chain of (A) is a C.sub.10 -C.sub.40 alkyl or alkenyl group; and the hydraulic material is cement.

8. The hydraulic composition according to claim 7, wherein the degree of replacement by the substituent (A) is 0.001 to 1 per monosaccharide unit as determined by NMR spectrometry; and that by the substituent (B) is 0.01 to 2 per monosaccharide unit as determined by colloidal titration.

9. The hydraulic composition according to claim 5, wherein the polysaccharide derivative is an alkylated or hydroxyalkylated polysaccharide; the hydrocarbon chain of the substituent (A) has 8 to 40 carbon atoms; the degree of replacement by the substituent (A) is 0.0001 to 1 per monosaccharide unit as determined by Zeisel's method or the diazomethane method; and that by the substituent (B) is 0.001 to 2 per monosaccharide unit as determined by colloidal titration.

10. The hydraulic composition according to claim 5, wherein the substituent (A) is at least one member selected from the group consisting of alkyl glyceryl ether groups wherein the alkyl group is a C.sub.8 -C.sub.40 linear or branched alkyl, alkenyl glyceryl ether groups wherein the alkenyl group is a C.sub.8 -C.sub.40 linear or branched alkyl, and C.sub.8 -C.sub.40 linear and branched alkyl, alkenyl and acyl groups which may be hydroxylated or interruptedbyoxycarbonyl; and the substituent (B) is at least one member selected from the group consisting of sulfoalkyl, carboxyalkyl, alkyl phosphate and alkyl sulfate groups each of which has 1 to 5 carbon atoms and may be hydroxylated; and salts thereof.

11. The hydraulic composition according to claim 5, wherein the substituent (A) is an alkyl glyceryl ether group wherein the alkyl group is a C.sub.12 -C.sub.36 linear alkyl.

12. The hydraulic composition according to claim 5, wherein the hydraulic material is an inorganic substance which can be hardened through hydration.

13. The hydraulic composition according to claim 5 or 9, wherein the hydraulic material is hemihydrate gypsum.

14. The hydraulic composition according to claim 5 or 9, wherein the hydraulic material is ordinary portland cement, blast-furnace slag cement or silica cement.

15. The hydraulic composition according to claim 5 or 9, which further comprises a super plasticizer in an amount of 0.0001 to 3% by weight, based on the weight of the hydraulic composition.

16. The hydraulic composition according to claim 15, wherein the super plasticizer is a (co)polymer prepared from one or two or more monomers selected from the group consisting of ethylenically unsaturated carboxylic acids, adducts thereof with alkylene oxides, and derivatives thereof, or a condensate of formaldehyde with one or two or more compounds selected from the group consisting of methylolated and sulfonated derivatives of naphthalene, melamine, phenol, urea and aniline.

17. The hydraulic composition according to claim 15, wherein the super plasticizer is a water-soluble vinyl copolymer comprising oxyalkylene units and prepared by copolymerizing a monomer represented by the following general formula (1) with at least one monomer selected from those represented by the following general formulae (2) or (3): ##STR4## (wherein R.sub.1 and R.sub.2 are each hydrogen or methyl; m.sub.1 is a number of 0 to 2; AO is C.sub.2 -C.sub.3 oxyalkylene; n is a number of 2 to 300; and X is hydrogen or C.sub.1 -C.sub.3 alkyl) ##STR5## (wherein R.sub.3, R.sub.4 and R.sub.5 are each hydrogen, methyl or (CH.sub.2).sub.m2 COOM.sub.2 ; R.sub.6 is hydrogen or methyl; M.sub.1, M.sub.2 and Y are each hydrogen, alkali metal, alkaline earth metal, ammonium, alkylammonium or substituted alkylammonium; and m.sub.2 is a number of 0 to 2).

18. The hydraulic composition according to claim 15 wherein the super plasticizer is selected from the group consisting of condensates of formaldehyde with at least one selected from the group consisting of methylolated and sulfonated derivatives of naphthalene, melamine, phenol, urea and aniline.

19. The hydraulic composition according to claim 15, wherein the amount of superplasticizer is 0.001 to 0.5% by weight, based on the hydraulic material.

20. The hydraulic composition according to claim 5, wherein the amount of polysaccharide derivative is 0.001 to 5% by weight, based on the hydraulic material.

21. The hydraulic composition according to claim 19, wherein the amount of superplasticizer is 0.001 to 0.1% by weight, based on the hydraulic material.

22. The hydraulic composition according to claim 15, wherein the super plasticizer is comprised of condensates of formaldehyde with metal salts of naphthalenesulfonic acid, condensates of formaldehyde with metal salts of melaminesulfonic acid, condensates of formaldehyde with phenolsulfonic acid, or co-condensates of formaldehyde with phenol and sulfanilic acid.

23. The hydraulic composition according to claim 15, wherein the super plasticizer is comprised of a water-soluble vinyl copolymer comprising oxyalkylene units.

24. The hydraulic composition according to claim 15, wherein the super plasticizer is comprised of polymers and copolymers prepared from one or more monomers selected from the group consisting of ethylenically unsaturated carboxylic acids, adducts thereof with alkylene oxides, and derivatives thereof.

25. A method for preparing a hydraulic composition comprising:

mixing a polysaccharide derivative prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative with (A) a hydrophobic substituent having a C.sub.8 -C.sub.43 hydrocarbon chain and (B) an ionic hydrophilic substituent having at least one member selected from the group consisting of sulfonic, carboxylic, phosphoric, and sulfate groups and salts thereof with a hydraulic material and water.

PRIOR ART

The present invention relates to a novel polysaccharide derivative, particularly one which forms an aqueous solution excellent in transparency and thickening effects even at a low concentration and reduced in the viscosity change caused by the coexistence of a metal salt or a temperature change, thus exhibiting excellent flowability, and a process for the preparation thereof. The present invention relates also to an admixture for the production of extruded articles. Specifically, it relates to an admixture which imparts suitable plasticity for extrusion to a plastic cement composition prepared by mixing a cementitious material as the major component with water to thereby enable the production of an extruded plate excellent in shape retention through the formation of smooth surfaces without causing crushing, and to a cement composition containing the admixture. The present invention relates also to an additive for gypsum-based adhesives excellent in adhesiveness and to a gypsum-based adhesive containing this additive. More specifically, it relates to an additive for gypsum-based adhesives mainly comprising cementitious materials such as hemihydrate gypsum which is effective in enhancing the adhesive bonding of a gypsum molding to a substrate and to an adhesive composition containing the additive. The present invention relates also to an additive for mortar and to a mortar composition containing the additive. More specifically, it relates to an additive for various mortars to be used in wooden buildings, concretebuildingsorthelikeas substrate, finishor the like, which additive can give a mortar composition excellent in the capability of plastering and extremely reduced in the delay of setting or development of strength. The present invention relates also to an additive for high-flowability hydraulic compositions which need not be compacted, a hydraulic composition containing this additive, and a hardened product of the composition. More specifically, it relates to an additive for hydraulic compositions which can increase the viscosity and flowability of concrete, mortar and cement paste used as civil engineering and building materials and the materials for secondary products and can protect the compositions from the segregation caused among aggregate, cement and water. The hydraulic composition containing this additive need not be compacted with a vibrator or the like and exhibits excellent hardening characteristics in placing.

BACKGROUND ART

Cellulose ethers are somewhat superior to polyacrylate thickeners such as Carbopol in the viscosity stability of an aqueous solution thereof with an inorganic or organic metal salt. However, cellulose ethers had disadvantages such that their thickening effects were poorer than those of polyacrylate thickeners at the same concentration, and that the viscosity of a hydraulic composition containing cellulose ether as the thickener or dispersant remarkably changed with the temperature.

JP-A 55-110103 and JP-A 56-801 disclose that hydrophobic nonionic cellulose derivatives prepared by partially introducing C.sub.10 -C.sub.24 long-chain alkyl groups into nonionic water-soluble cellulose ethers exhibit relatively high thickening effects even when used in small amounts. Further, attempts to apply such alkylated cellulose derivatives to pharmaceutical preparations for external use, cosmetics and so on are disclosed in JP-A 3-12401, JP-A 3-141210, JP-A 3-141214 and JP-A 3-218316. However, these alkylated cellulose derivatives had problems that they were poor in water solubility, so that it took a long time to dissolve the derivatives homogeneously and that the viscosity of the resulting aqueous solution significantly changed with of time, though they were superior to the above cellulose ethers in thickening effects.

As described above, the cellulose ethers and alkylated cellulose derivatives according to the prior art could not satisfy all of the requirements for the ideal thickener for building materials and so on, i.e., easy dissolution, excellent thickening effect, high dispersion stabilizing effect, no damage to the flowability of building materials, low dependence of the viscosity on coexistent metal salts, surfactants or additives, temperature or pH change, excellent an timicrobial properties, and so on.

JP-A 61-256957 discloses an attempt at imparting plasticity to a mixture of a cementitious material with water by the addition of a water-soluble polymer such as methylcellulose, hydroxymethylcellulose and carboxy-methylcellulose to thereby inhibit the die pressure from lowering and to thereby improve the shape retention of an extrudate. However, the use of such a polymer was not sufficiently effective in inhibiting the die pressure from lowering or in improving the shape retention, and the resulting extruded plate was poor in surface smoothness and appearance. Thus, a further improvement has been expected.

DISCLOSURE OF THE INVENTION

Under these circumstances, the inventors of the present invention have intensively studied to find that a novel polysaccharide derivative prepared by replacing the hydroxyl hydrogen atoms of a polysaccharide by a specific hydrophobic substituent and a sulfonated substituent is excellent in water solubility, that an aqueous solution of the novel polysaccharide derivative exhibits a high thickening effect even at a low concentration, and the viscosity depends little on a coexistent inorganic or organic metal salt, pH, temperature or the like, that the polysaccharide derivative exhibits also an excellent dispersing effect, and that building materials containing the derivative exhibit an excellent flowability. The present invention has been accomplished on the basis of these findings.

The inventors of the present invention have also found that when the derivative is used as an admixture in producing excluded plates, it is extremely effective in inhibiting the die pressure of a molding cylinder from lowering and in improving the shape retention and surface smoothness of extruded plates. Further, they have also found that the polysaccharide derivative exhibits an excellent thickening effect even under high-ionic-strength conditions and even when used in an extremely small amount, so that a gypsum-based adhesive containing the derivative as the additive is remarkably effective in bonding a gypsum molding such as gypsum board to a substrate. The inventors of the present invention have also found that when the derivative is used as the additive for mortar, the resulting exhibits an excellent capability of plastering mortar like the mortar of the prior art containing a water-soluble polymer, is reduced in the delay of setting, and is remarkably excellent in the development of initial strength. The inventors of the present invention have also found that by virtue of the excellent thickening effect of the polysaccharide derivative exhibited even under high-ionic-strength conditions and even when used in an extremely small amount, a hydraulic composition containing both the derivative as a thickener together with a super plasticizer can be improved in the flowability and segregation resistance and can be minimized in the suppression of hydration of hydraulic powder to exhibit a remarkably excellent initial strength.

The present invention relates to a polysaccharide derivative prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative by (A) a hydrophobic substituent having a C.sub.8 -C.sub.43 hydrocarbon chain as the partial structure and (B) an ionic hydrophilic substituent having at least one member selected from the group consisting of sulfo or sulfonic, carboxyl, phosphoric, and sulfate groups and salts thereof as the partial structure, wherein the average degree of replacement by the substituent (A) is 0.0001 or above but below 0.001 per constituent monosaccharide residue as determined by Zeisel's method or the diazomethane method and that by the substituent (B) is 0.01 to 2.0 per constituent monosaccharide residue as determined by colloidal titration.

The polysaccharide or polysaccharide derivative to be used in the present invention as the raw material is preferably selected from the group consisting of cellulose, guar gum, starch, hydroxyethylcellulose, hydroxyethyl guar gum, hydroxyethylstarch, methylcellulose, methyl guar gum, methylstarch, ethylcellulose, ethyl guar gum, ethylstarch, hydroxypropylcellulose, hydroxypropyl guar gum, hydroxypropylstarch, hydroxyethylmethylcellulose, hydroxyethylmethyl guar gum, hydroxyethylmethylstarch, hydroxypropylmethylcellulose, hydroxypropylmethyl guar gum and hydroxypropylmethylstarch.

It is preferable that the substituent (A) be a C.sub.10 -C.sub.43 linear or branched alkyl, alkenyl or acyl group which may be hydroxylated or interrupted by oxycarbonyl (--COO-- or --OCO--) or an ether linkage and the substituent (B) be an optionally hydroxylated C.sub.1 -C.sub.5 sulfoalkyl group or a salt thereof.

Further, it is also preferable that the substituent (A) be one or more members selected from among C.sub.12 -C.sub.36 linear and branched alkyl, alkenyl and acyl groups which may be hydroxylated or interrupted by an ether linkage and the substituent (B) be one or more members selected from among 2-sulfoethyl, 3-sulfopropyl, 3-sulfo-2-hydroxypropyl and 2-sulfo-1-(hydroxymethyl)ethyl.

Further, the present invention also provides a process for the preparation of the above polysaccharide derivative by reacting a polysaccharide or a polysaccharide derivative with both (a) a hydrophobizing agent selected from among glycidyl ethers, epoxides, halides and halohydrins each of which has a C.sub.10 -C.sub.40 linear or branched alkyl or alkenyl group, and esters, acid halides and carboxylic anhydrides wherein the acyl group is a C.sub.10 -C.sub.40 linear or branched, saturated or unsaturated one and (b) a sulfonating agent selected from among vinylsulfonic acid, optionally hydroxylated C.sub.1 -C.sub.5 haloalkanesulfonic acids and salts thereof.

Furthermore, the present invention relates to a hydraulic composition comprising a hydraulic material and a polysaccharide derivative prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative by (A) a hydrophobic substituent having a C.sub.8 -C.sub.43 hydrocarbon chain as the partial structure and (B) an ionic hydrophilic substituent having at least one member selected from the group consisting of sulfonic, carboxyl, phosphoric, and sulfate groups and salts thereof as the partial structure.

A preferable example of the hydraulic composition of the present invention is one as described above wherein the substituent (A) is a C.sub.10 -C.sub.43 linear or branched alkyl, alkenyl or acyl group which may be hydroxylated or interrupted by oxycarbony (--COO-- or --OCO--) or an ether linkage, the substituent (B) is an optionally hydroxylated C.sub.1 -C.sub.5 sulfoalkyl group or a salt thereof, the average degree of replacement by the substituent (A) is 0.0001 or above but below 0.001 per constituent monosaccharide residue as determined by Zeisel's method or the diazomethane method, and that by the substituent (B) is 0.01 to 2.0 per constituent monosaccharide residue as determined by colloidal titration.

Another preferable example of the hydraulic composition is one as described above wherein the polysaccharide derivative to be used as the raw material is an alkylated or hydroxyalkylated polysaccharide, the hydrocarbon chain of the substituent (A) is a C.sub.10 -C.sub.40 alkyl or alkenyl group, and the hydraulic material is cement. In this composition, it is desirable that the degree of replacement by the substituent (A) is 0.001 to 1 per constituent monosaccharide residue as determined by NMR spectrometry and that by the substituent (B) is 0.01 to 2 per constituent monosaccharide residue as determined by colloidal titration. Further, it is also desirable that the substituent (A) is at least one member selected from the group consisting of alkyl glyceryl ether groups wherein the alkyl group is a C.sub.8 -C.sub.40 linear or branched one, alkenyl glyceryl ether groups wherein the alkenyl group is a C.sub.8 -C.sub.40 linear or branched one, and C.sub.8 -C.sub.40 linear and branched alkyl, alkenyl and acyl groups which may be hydroxylated or interrupted by oxycarbonyl, and that the substituent (B) is an optionally hydroxylated C.sub.1 -C.sub.5 sulfoalkyl group or a salt thereof. It is more desirable that the substituent (A) is an alkyl glyceryl ether group wherein the alkyl group is a C.sub.12 -C.sub.36 linear one.

Another preferable example of the hydraulic composition is one as described above wherein the polysaccharide derivative to be used as the raw material is an alkylated or hydroxyalkylatedpolysaccharide, thehydrocarbonchainof the hydrophobic substituent (A) has 8 to 40 carbon atoms, the degree of replacement by the substituent (A) is 0.0001 to 1 per constituent monosaccharide residue as determined by Zeisel's method or the diazomethane method, and that by the substituent (B) is 0.001 to 2 per constituent monosaccharide residue as determined by colloidal titration.

Another preferable example of the hydraulic composition is one as described above wherein the substituent (A) is at least one member selected from the group consisting of alkyl glyceryl ether groups wherein the alkyl group is a C.sub.8 -C.sub.40 linear or branched one, alkenyl glyceryl ether groups wherein the alkenyl group is a C.sub.8 -C.sub.40 linear or branched one, and C.sub.8 -C.sub.40 linear and branched alkyl, alkenyl and acyl groups which may be hydroxylated or interrupted by oxycarbonyl, and the substituent (B) is at least one member selected from the group consisting of sulfoalkyl, carboxyalkyl, alkyl phosphate and alkyl sulfate groups each of which has 1 to 5 carbon atoms and may be hydroxylated, and salts thereof.

Further, it is desirable that the substituent (A) is an alkyl glyceryl ether group wherein the alkyl group is a C.sub.12 -C.sub.36 linear one. It is also desirable that the substituent (A) is an alkyl glyceryl ether group wherein the alkyl group is a C.sub.12 -C.sub.36 linear one, and the substituent (B) is an optionally hydroxylated C.sub.1 -C.sub.5 sulfoalkyl group.

According to the present invention, it is preferable that the polysaccharide derivative be contained in an amount of 0.0001 to 3% by weight based on the hydraulic material. The hydraulic material may be an inorganic substance which can be hardened through hydration or hemihydrate gypsum. Alternatively, the hydraulic material may be portland cement, blast-furnace slag cement or silica cement. The hydraulic composition may further contain fine aggregate or super plasticizer.

The super plasticizer is preferably a (co)polymer prepared from one or more monomers selected from the group consisting of ethylenically unsaturated carboxylic acids, adducts thereof with alkylene oxides, and derivatives thereof, or a condensate of formaldehyde with one or more compounds selected from the group consisting of methylolated and sulfonated derivatives of naphthalene, melamine, phenol, urea and aniline. It is still preferable that the super-plasticizer be a water-soluble vinyl copolymer comprising oxyalkylene units and prepared by copolymerizing a monomer represented by the following general formula (1) with at least one monomer selected from among those represented by the following general formulae (2) and (3). ##STR1## wherein R.sub.1 and R.sub.2 are each hydrogen, methyl; m.sub.1 is a number of 0 to 2; AO is C.sub.2 -C.sub.3 oxyalkylene; n is a number of 2 to 300; and X is hydrogen or C.sub.1 -C.sub.3 alkyl. ##STR2## wherein R.sub.3, R.sub.4 and R.sub.5 are each hydrogen, methyl or (CH.sub.2).sub.m2 COOM.sub.2 ; R.sub.6 is hydrogen or methyl; M.sub.1, M.sub.2 and Y are each hydrogen, alkali metal, alkaline earth metal, ammonium, alkylammonium or substituted alkylammonium; and m.sub.2 is a number of 0 to 2.

It is desirable that the amounts of the polysaccharide derivative and super plasticizer to be used are 0.0001 to 3% by weight and 0.1 to 5% by weight, respectively, based on the hydraulic material. It is preferable that the composition exhibit a slump flow value of 50 to 70 cm as determined by the slump test stipulated in JIS A 1101.

The hydraulic composition of the present invention is used as self-compacting concrete.

The present invention relates also to an additive for hydraulic materials which comprises the above polysaccharide derivative, a process for preparing a hydraulic composition by mixing the polysaccharide derivative with a hydraulic material and water, and the use of the polysaccharide derivative as the admixture for hydraulic materials.

The polysaccharide derivative of the present invention is usable as an admixture for the production of extruded articles. Further, it is applicable to gypsum-based adhesives, cementitious materials and mortar.

The polysaccharide derivative may be used in an amount of 0.0001 to 0.03% by weight based on the hydraulic material.

The average degree of replacement by the substituent (B) can be determined by colloidal titration and that by the substituent (A) can be determined by Zeisel's method, the diazomethane method or NMR spectrometry.

DETAILED DESCRIPTION OF THE INVENTION

Description will now be made of the embodiments according to the present invention, the embodiment 1 relating to polysaccharide derivatives and the embodiments 2 to 5 relating to hydraulic compositions.

Embodiment 1

When the novel polysaccharide derivative is prepared from a cellulose, it comprises repeating units represented by the following general formula 1-1: ##STR3## wherein R's are each independently a member selected from among (1) hydrogen, methyl, ethyl, hydroxylethyl, hydroxypropyl and so on, (2) the hydrophobic substituent (A) and (3) optionally hydroxylated sulfoalkyl groups (B), A's are each independently C.sub.2 -C.sub.4 alkylene, and a, b and c are each independently a number of 0 to 10, with the provisos that AO's, R's, a's, b's, and c's may respectively be the same as or different from each other either in one repeating unit or among repeating units and that the average degrees of replacement by the substituents (A) and (B) are 0.0001 or above but below 0.001 and 0.01 to 2.0 respectively, per constituent monosaccharide residue, with the remainder of R's being each a member selected from among those described in the item (1).

As represented by the above general formula, both the hydrophobic substituent (A) and an optionally hydroxylated sulfoalkyl group (B) are contained as the substituent R in the polysaccharide derivative. However, it does not mean that both of the substituents (A) and (B) must always be present in one constituent monosaccharide residue, but that it will suffice in the present invention when both of the substituents are present in one polysaccharide molecule as a whole each at the above average degree of replacement. The remainder of R's are each independently hydrogen, methyl, ethyl, hydroxyethyl, hydroxypropyl or the like.

The C.sub.10 -C.sub.43 alkyl and alkenyl groups to be introduced as the hydrophobic substituent (A) include linear alkyl groups such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, triacontyl, hentriacontyl, dotriacontyl, tritriacontyl, tetratriacontyl, pentatriacontyl, hexatriacontyl, heptatriacontyl, octatriacontyl, nonatriacontyl and tetracontyl; branched alkyl groups such as methylundecyl, methylheptadecyl, ethylhexadecyl, methyloctadecyl, propylpentadecyl, 2-hexyldecyl, 2-octyldodecyl, 2-heptylundecyl, 2-decyltetradecyl, 2-dodecylhexadecyl, 2-tetradecyloctadecyl and 2-tetradecylbehenyl; and alkenyl groups such as decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, icosenyl, henicosenyl, docosenyl, tricosenyl, tetracosenyl, pentacosenyl, hexacosenyl, heptacosenyl, octacosenyl, nonacosenyl, triacontenyl, oleyl, linoleyl and linolenyl. Among these groups, C.sub.12 -C.sub.36, particularly C.sub.16 -C.sub.24, linear and branched alkyl and alkenyl groups are preferable, and such alkyl groups, particularly linear ones are still preferable in respect of stability. The hydrophobic substituent (A) includes not only these alkyl and alkenyl groups but also groups derived from the alkyl and alkenyl groups through hydroxylation, for example, 2-hydroxyalkyl, 1-hydroxymethylalkyl, 2-hydroxyalkenyl and 1-hydroxymethylalkenyl; groups derived therefrom through the introduction of an ether linkage, for example, 2-hydroxy-3-alkoxypropyl, 2-alkoxy-3-hydroxypropyl, 2-hydroxy-3-alkenyloxypropyl and 2-alkenyloxy-3-hydroxypropyl; groups derived therefrom by the replacement by an oxo group at the position 1, for example, 1-oxoalkyl and 1-oxoalkenyl groups (i.e., acyl groups); and groups derived therefrom through the introduction of oxycarbonyl. Among these groups, optionally hydroxylated alkyl, alkenyl, alkoxypropyl, alkenyloxypropyl and acyl groups are preferable, with 2-hydroxyalkyl and alkoxyhydroxypropyl being particularly preferable from the standpoints of stability and easiness of preparation.

The hydrophobic substituent (A) may be replaced for either the hydrogen atom of a hydroxyl group directly bonded to a polysaccharide molecule or the hydrogen atom of the hydroxy group of a hydroxylethyl or hydroxylpropyl group bonded to the molecule. The degree of replacement by the hydrophobic substituent (A) may suitably be selected within the range of 0.0001 to 0.001 per constituent monosaccharide residue.

The optionally hydroxylated sulfoalkyl group (B) includes 2-sulfoethyl, 3-sulfopropyl, 3-sulfo-2-hydroxypropyl, and 2-sulfo-1-(hydroxymethyl)ethyl, among which 3-sulfo-2-hydroxypropyl is preferable from the standpoints of stability and easiness of preparation. The whole or part of the substituent (B) may form a salt together with an alkali metal such as Na and K, an alkaline earth metal such as Ca and Mg, an organic cation derived from an amine or ammonium ion. The substituent (B) may also be replaced for either the hydrogen atom of a hydroxyl group directly bonded to a polysaccharide molecule or the hydrogen atom of the hydroxy group of a hydroxylethyl or hydroxylpropyl group bonded to the molecule. The degree of replacement by the substituent (B) may suitably be selected within the range of 0.01 to 2.0 per constituent monosaccharide residue in accordance with the amount of the substituent (A) introduced. It is preferable that the degree of replacement be 0.01 to 1.0, still preferably 0.02 to 0.5 per constituent monosaccharide residue.

The novel polysaccharide derivative of the present invention can be prepared by conducting the replacement of part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative by the hydrophobic group (A) (introduction of the hydrophobic substituent (A)) or the sulfonation thereof (introduction of the sulfonated substituent (B)) and thereafter conducting the sulfonation of all or part of the remaining hydroxyl hydrogen atoms or the replacement thereof by the hydrophobic group, or by conducting the replacement by the hydrophobic group and the sulfonation simultaneously.

The polysaccharide or polysaccharide derivative to be used in the present invention includes polysaccharides, such as cellulose, guar gum and starch, and polysaccharide derivatives prepared by substituting the above polysaccharides with methyl, ethyl, hydroxyethyl or hydroxypropyl group. These substituting groups may be present, in a constituent monosaccharide residue each alone or as a combination of two or more of them. Examples of such polysaccharide derivatives include hydroxyethylcellulose, hydroxyethyl guar gum, hydroxyethylstarch, methylcellulose, methyl guar gum, methylstarch, ethylcellulose, ethyl guar gum, ethylstarch, hydroxypropylcellulose, hydroxypropyl guar gum, hydroxypropylstarch, hydroxyethylmethylcellulose, hydroxyethylmethyl guar gum, hydroxyethylmethylstarch, hydroxypropylmethylcellulose, hydroxypropylmethyl guar gum and hydroxypropylmethylstarch. Among these polysaccharides and polysaccharide derivatives, cellulose, hydroxyethylcellulose, methylcellulose, ethylcellulose and hydroxypropylcellulose are preferable, hydroxyethylcellulose being particularly preferable. Although the above polysaccharide derivative can have a degree of replacement exceeding 3.0 per constituent monosaccharide residue by further replacing the hydroxyl groups of the hydroxyethyl or hydroxypropyl group to form a polyoxyethylene chain or the like. It is preferable that the degree of replacement be 0.1 to 10.0, particularly 0.5 to 5.0 per constituent monosaccharide residue. Further, it is desirable that the polysaccharide or polysaccharide derivative has a weight-average molecular weight of 10,000 to 10,000,000, more desirably 100,000 to 5,000,000, most desirably, 500,000 to 2,000,000.

"Hydrophobization" and "Sulfonation" will now be described separately. As described above, the hydrophobization may be conducted prior to the sulfonation or vice versa, or both of them may be conducted simultaneously.

(Hydrophobization)

The hydrophobization of a polysaccharide or a sulfonated polysaccharide can be conducted by dissolving or dispersing a polysaccharide or a sulfonated polysaccharide in a suitable solvent and reacting the polysaccharide or sulfonated polysaccharide with a hydrophobizing agent selected from among glycidyl ethers, epoxides, halides and halohydrins each of which has a C.sub.10 -C.sub.40 linear or branched alkyl or alkenyl group, and esters, acid halides and carboxylic anhydrides having a C.sub.10 -C.sub.40 linear or branched, saturated or unsaturated acyl group.

Among the above hydrophobizing agents, glycidyl ethers, epoxides, halides and acyl halides are particularly preferable, which may be used each alone or as a combination of two or more of them. Although the amount of the hydrophobizing agent to be used may suitably be selected in accordance with the desired amount of the hydrophobic substituent to be introduced into the polysaccharide or polysaccharide derivative, it is generally preferably 0.0001 to 1 equivalent, particularly preferably 0.0005 to 0.1 equivalent per constituent monosaccharide residue of the polysaccharide or polysaccharide derivative.

It is preferable that the hydrophobization be conducted in the presence of an alkali at need. Although the alkali to be used in this case is not particularly limited, it may be selected from among hydroxides, carbonates and bicarbonates of alkali metals and alkaline earth metals. Among them, it is preferable to use sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide or the like. Good results can be attained, when the molar amount of the alkali used is 1 to 1000 times, particularly 100 to 500 times that of the hydrophobizing agent used.

The solvent usable in this reaction includes lower alcohols such as isopropyl alcohol and tert-butyl alcohol. The reaction may be conducted in a mixed solvent prepared by adding 1 to 50% by weight, preferably 2 to 30% by weight of water to such a lower alcohol for the purpose of swelling the polysaccharide or sulfonated polysaccharide to thereby enhance the reactivity of the (sulfonated) polysaccharide with the hydrophobizing agent.

It is preferable that the reaction temperature be 0 to 200.degree. C., particularly 30 to 100.degree. C. After the completion of the reaction, the reaction mixture may be neutralized with an acid at need. The acid usable for this purpose includes mineral acids such as sulfuric acid, hydrochloric acid and phosphoric acid and organic acids such as acetic acid. Further, the reaction mixture may be subjected to the subsequent reaction without being neutralized.

The reaction mixture obtained by the above reaction can be used as such without being neutralized in the subsequent sulfonation step. Prior to the sulfonation, the reaction mixturemaybe subjectedatneed to fractionationby filtration or the like and/or washing with hot water, hydrous isopropyl alcohol, hydrous acetone or the like to thereby remove unreacted hydrophobizing agent and/or the salts formed by neutralization. When the sulfonation has been conducted prior to the hydrophobization, the novel polysaccharide derivative of the present invention can be obtained by subjecting the above reaction mixture to neutralization and fractionation by filtration or the like, and thereafter drying the product thus recovered, the drying being optionally preceded by the washing of the product.

<Sulfonation>

The sulfonation of a polysaccharide or a hydrophobized polysaccharide can be conducted by dissolving or dispersing a polysaccharide or a hydrophobized polysaccharide in a suitable solvent and reacting the same with a sulfonating agent.

The halogen atom constituting the optionally hydroxylated C.sub.1 -C.sub.5 haloalkanesulfonic acid to be used as the sulfonating agent includes fluorine, chlorine and bromine. Further, the salts of optionally hydroxylated C.sub.1 -C.sub.5 haloalkanesulfonic acids include salts thereof with alkali metals suchas sodiumandpotassium, alkalineearthmetals such as calcium and magnesium, and ammonium. Preferable examples of the sulfonating agent include vinylsulfonic acid, 3-halo-2-hydroxypropanesulfonic acids and 3-halopropanesulfonic acids, which may be used each alone or as a combination of two or more of them. Although the amount of the sulfonating agent to be used may suitably be selected in accordance with the desired amount of sulfonic acid group to be introduced into the polysaccharide or polysaccharide derivative, it is generallypreferably 0.01 to 10 equivalents, particularly preferably 0.03 to 1 equivalent per constituent monosaccharide residue of the polysaccharide or the hydrophobized polysaccharide.

It is preferable that the sulfonation be conducted in the presence of an alkali at need. Although the alkali to be used in this case is not particularly limited, it may be selected from among hydroxides, carbonates and bicarbonates of alkali metals and alkaline earth metals. Among them, it is preferable to use sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide or the like. Good results can be attained, when the molar amount of the alkali used is 1.0 to 3.0 times, particularly 1.05 to 1.5 times that of the sulfonating agent used.

The solvent usable in the sulfonation includes lower alcohols such as isopropyl alcohol and tert-butyl alcohol. The sulfonation may be conducted in a mixed solvent prepared by adding 0.1 to 100% by weight, preferably 1 to 50% by weight of water to such a lower alcohol for the purpose of enhancing the reactivity of the polysaccharide or the hydrophobized polysaccharide with the sulfonating agent.

It is preferable that the reaction temperature be 0 to 150.degree. C., particularly 30 to 100.degree. C. After the completion of the reaction, the reaction mixture may be neutralized with an acid at need. The acid usable for this purpose includes mineral acids such as sulfuric acid, hydrochloric acid and phosphoric acid and organic acids such as acetic acid. Further, the reaction mixture may be subjected to the subsequent reaction without being neutralized.

For hydrophobizing the polysaccharide thus sulfonated, the reaction mixture obtained by the above reaction can be used as such without being neutralized. Alternatively, the reaction mixture may be subjected prior to the hydrophobization to fractionation by filtration or the like and/or washing with hot water, hydrous isopropyl alcohol, hydrous acetone or the like to thereby remove unreacted sulfonating agent and/or the salts formed by neutralization. When the hydrophobization has been conducted prior to the sulfonation, the novel polysaccharide derivative of the present invention can be obtained by subjecting the reaction mixture to neutralization and fractionation by filtration or the like, and thereafter drying the product thus recovered, the drying being optionally preceded by the washing of the product.

The polysaccharide derivative of the present invention can favorably be used in various fields including building materials as thickener, dispersant or the like.

Embodiment 2

In a polysaccharide derivative, used as the admixture of the present invention, and prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or polysaccharide derivative by a specific hydrophobic substituent (A) and a specific ionic hydrophilic substituent (B). The hydrophobic substituent (A) is a group having as the partial structure a hydrocarbon chain having 8 to 40 carbon atoms, preferably 12 to 36 carbon atoms, still preferably 16 to 24 carbon atoms in total. Specific examples of such a group include alkyl glyceryl ether groups wherein the alkyl group is a linear or branched one having 8 to 40, preferably 12 to 36, still preferably 16 to 24 carbon atoms, alkenyl glyceryl ether groups wherein the alkenyl group is a linear or branched one having such a number of carbon atoms as described above, and C.sub.8 -C.sub.40, preferably C.sub.12 -C.sub.36, still preferably C.sub.16 -C.sub.24 linear and branched, alkyl, alkenyl and acyl groups which may be hydroxylated or interrupted by oxycarbonyl. The term "alkyl gryceryl ether group" used in this description refers to a residue obtained by removing one hydroxyl group from an alkyl glyceryl ether. More specific examples of the hydrophobic substituent (A) include 2-hydroxy-3-alkoxypropyl, 2-alkoxy-1-(hydroxymethyl)ethyl, 2-hydroxy-3-alkenyloxypropyl and 2-alkenyloxy-1-(hydroxymethyl)ethyl. The hydrophobic substituent (A) may replace the hydroxyl hydrogen atom of a hydroxyethyl or hydroxypropyl group bonded to a polysaccharide molecule.

The ionic hydrophilic substituent (B) has as the partial structure a sulfonic, carboxyl, phosphoric or sulfate group which may form a salt. Specific examples thereof include sulfoalkyl and carboxylalkyl groups each of which has 1 to 5 carbon atoms and may be hydroxylated, and salts thereof. More specific examples thereof include 2-sulfoethyl, 3-sulfopropyl, 3-sulfo-2-hydroxypropyl and 2-sulfo-1-(hydroxymethyl) ethyl, the whole or part of which may form salts together with alkali metals such as Na and K, alkaline earth metals such as Ca and Mg, organic cations derived from amines or the like, or ammonium ion.

The solubility of the polysaccharide derivative of the present invention in mixing water and the thickening effects thereof depend on the degrees of replacement by the hydrophobic substituent (A) and the ionic hydrophilic substituent (B).

More precisely, when the degrees of replacement are below their respective desired ranges, the resulting polysaccharide derivative will be poor in the solubility in mixing water, or the hydraulic composition containing it will be too low in viscosity to exhibit satisfactory shape retention. On the contrary, when the degrees of replacement are above their respective desired ranges, the resulting polysaccharide derivative will be poor in the solubility in mixing water, or the resulting hydraulic composition will be too viscous, which will bring about an increase in molding pressure to result in unsatisfactory surface smoothness. For such reasons, it is preferable that the degree of replacement by the hydrophobic substituent (A) be 0.001 to 1, still preferably 0.01 to 0.1 per constituent monosaccharide residue, while that by the ionic hydrophilic substituent (B) be 0.01 to 2, still preferably 0.02 to 1.5 per constituent monosaccharide residue. It is particularly preferable that the degrees of replacement by the substituents (A) and (B) be 0.01 to 0.1 and 0.1 to 0.6, respectively.

The replaced polysaccharide derivative to be used in the present invention can be prepared by hydrophobizing part of the hydroxyl hydrogen atoms of a polysaccharide or an alkylated or hydroxyalkylated derivative thereof (introduction of the hydrophobic substituent (A)) or hydrohpilizing the same through sulfonation or the like (introduction of the ionic hydrophilic substituent (B)) and thereafter hydrophilizing all or part of the remaining hydroxyl hydrogen atoms such as sulfonation or hydrophobizing the same, or by conducting the hydrophobization and the hydrophilization, such as sulfonation, simultaneously.

The polysaccharide to be used in preparing the polysaccharide derivative according to the present invention as the raw material includes cellulose; starch; rhizome polysaccharides such as konjak mannan and sticky matter obtained from sunset hibicus; sap polysaccharides such as gum arabic, tragacanth gum and karaya gum; seed polysaccharides such as locust bean gum, guar gum and tamarind gum; marine plant polysaccharides such as agar-agar, carrageenan and algin; animal polysaccharides such as chitin, chitosan, heparin and chondroitin sulfate; and microbial polysaccharides such as dextran and xanthan gum. The polysaccharide substituted with an ionic group includes those substituted with anionic groups, for example, carboxymethylcellulose, cellulose sulfate, cellulose phosphate and cellulose phosphite. The alkylated or hydroxyalkylated derivative of polysaccharide includes hydroxyethylcellulose, hydroxyethyl guar gum, hydroxyethylstarch, methylcellulose, methyl guar gum, methylstarch, ethylcellulose, ethyl guar gum, ethylstarch, hydroxypropylcellulose, hydroxypropyl guar gum, hydroxypropylstarch, hydroxyethylmethylcellulose, hydroxyethylmethyl guar gum, hydroxyethylmethylstarch, hydroxypropylmethylcellulose, hydroxypropylmethyl guar gum and hydroxypropylmethylstarch. Among these polysaccharides, it is preferable to use the cellulose such as cellulse, hydroxyethylcellulose, methylcellulose, ethylcellulose and hydroxypropylcellulose, and the derivativs thereof. The polysaccharide derivative to be used as the raw material may have one kind of substituents selected from among methyl, ethyl, hydroxyethyl, hydroxypropyl and so on, or two or more kinds of substituents selected therefrom. The degree of replacement is preferably 0.1 to 5, particularly preferably 0.5 to 3 per constituent monosaccharide residue.

When the substituent is an oxyalkylene group, the degree of replacement, i.e., the number of oxyalkylene units added is preferably 0.1 to 10, particularly preferably 0.5 to 5 per constituent monosaccharide residue. It is preferable that the polysaccharide or polysaccharide derivative to be used as the raw material has a weight-average molecular weight of 10,000 to 10,000,000, particularly 100,000 to 5,000,000.

The introduction of the substituents can be conducted by, for example, reacting a polysaccharide or a polysaccharide derivative with an alkyl or alkenyl glycidyl ether wherein the alkyl or alkenyl group has 10 to 40 carbon atoms, an epoxide, halide, halohydrin or acyl halide having a C.sub.10 -C.sub.40 linear or branched, saturated or unsaturated alkyl group, or an ester or carboxylic anhydride wherein the acyl group has 10 to 40 carbon atoms in the presence of an alkali to introduce the hydrophobic substituent (A) and then reacting the resulting polysaccharide with vinylsulfonic acid, an optionally hydroxylated C.sub.1 -C.sub.5 haloalkanesulfonic acid or a salt thereof in the presence of an alkali.

The cement composition for the production of extruded articles according to the present invention essentially comprises a cementitious material and the above admixture.

The cementitious material to be used in the present invention includes portland cements of normal, high-early-strength, super-high-early-strength and white types, blast-furnace slag cement, fly ash cement, and alumina cement.

The above admixture for the cement composition to be used in producing extruded articles is used in an amount of 0.1 to 7 parts by weight, preferably 1 to 5 parts by weight per 100 parts by weight of the cementitious material.

The cement composition for the production of extruded articles according to the present invention may further contain other various admixtures and/or additives. Such admixtures and additives include various fibrous reinforcements such as asbestos, glass fiber, polypropylene fiber, Vinylon fiber and aramide fiber; lightweight aggregates such as perlite and vermiculite; fillers such as blast furnace slag, fly ash, fumed silica, pulverized stone and silica sand; expanding admixture such as bentonite; surfactants such as plasticizer; retarder; and high-early-strength agent.

An extruded article can be produced by blending the above materials, mixing the obtained blend with a necessary amount of mixing water and extruding the resulting mixture into a predetermined shape through a die set on the head of a screw-type or plunger-type extruder. Mixing water is used in an amount of 15 to 85 parts by weight, preferably 15 to 60 parts by weight per 100 parts by weight of the cementitious material. The extrudate thus obtained is cut in desired lengths, and cured, if necessary, by using steam or an autoclave. Thus, a final extruded product can be obtained.

Embodiment 3

In the present invention, a polysaccharide derivative used as a thickener is prepared by replacing all or part of the hydroxyl hydrogen atoms of a polysaccharide or an alkylated or hydroxyalkylated derivative thereof by a specific hydrophobic substituent (A) and a specific ionic hydrophilic substituent (B) The hydrophobic substituent (A) is a group having as the partial structure a C.sub.8 -C.sub.40 hydrocarbon chain. Specific examples of such a group include alkyl glyceryl ether groups wherein the alkyl group is a linear or branched one having 8 to 40, preferably 12 to 36, still preferably 16 to 24 carbon atoms, alkenyl glyceryl ether groups wherein the alkenyl group is a linear or branched one having such a number of carbon atoms as described above, and C.sub.8 -C.sub.40, preferably C.sub.12 -C.sub.36, still preferably C.sub.16 -C.sub.24 linear and branched alkyl, alkenyl and acyl groups which may be hydroxylated or interrupted by oxycarbonyl. The alkyl glyceryl ether groups, long-chain alkyl groups and 2-hydroxylated long-chain alkyl groups are preferable from the standpoint of easiness of preparation, with the alkyl glyceryl ether groups being particularly preferable. The term "alkyl glyceryl ether group" used in this description refers to a residue obtained by removing one hydroxyl group from an alkyl glyceryl ether. More specific examples of the alkyl glyceryl ether group include 2-hydroxy-3-alkoxypropyl, 2-alkoxy-1-(hydroxymethyl)ethyl, 2-hydroxy-3-alkenyloxypropyl and 2-alkenyloxy-1-(hydroxymethyl)ethyl. The hydrophobic substituent (A) may replace the hydrogen atom of a hydroxyethyl or hydroxypropyl group bonded to a polysaccharide molecule.

The ionic hydrophilic substituent (B) has as the partial structure at least one member selected from the group consisting of sulfonic, carboxyl, phosphoric and sulfate groups which may form salts. Specific examples thereof include sulfoalkyl, carboxylakyl, alkyl phosphate and alkyl sulfate groups each of which has 1 to 5 carbon atoms and may be hydroxylated, and salts thereof. Preferable examples thereof include optionally hydroxylated C.sub.1 -C.sub.5 sulfoalkyl groups. More specific examples thereof include 2-sulfoethyl, 3-sulfopropyl, 3-sulfo-2-hydroxypropyl and 2-sulfo-1-(hydroxymethyl)ethyl, the whole or part of which may form salts together with alkali metals such as Na or K, alkaline earth metals such as Ca or Mg, organic cations derived from amines or the like, or ammonium ion.

The solubility of the polysaccharide derivative of the present invention in mixing water and the thickening effects thereof depend on the degrees of replacement by the hydrophobic substituent (A) and the ionic hydrophilic substituent (B). Precisely, the polysaccharide derivative according to the present invention can exhibit a suitable solubility in mixing water and satisfactory thickening effects and thus imparts excellent adhesiveness to gypsum-based adhesives, when the degrees of replacement by the substituents (A) and (B) lie within their respective preferable ranges. For these reasons, it is preferable that the degree of replacement by the hydrophobic substituent (A) be 0.0001 to 1, still preferably 0.0005 to 0.01 per constituent monosaccharide residue. Further, it is preferable that the degree of replacement by the ionic polar substituent (B) be 0.001 to 2, still preferably 0.01 to 1 per constituent monosaccharide residue. It is particularly preferable that the degrees of replacement by the substituents (A) and (B) be 0.0007 to 0.005 and 0.02 to 0.15 respectively.

The polysaccharide to be used in the present invention as the raw material may be selected from among those described in the embodiment 2.

The replaced polysaccharide derivative to be used in the present invention can be prepared by hydrophobizing part of the hydroxyl hydrogen atoms of a polysaccharide or an alkylated or hydroxyalkylated derivative thereof (introduction of the hydrophobic substituent (A)) or hydrophilizing the same (introduction of the ionic hydrophilic substituent (B)) and thereafter hydrophobizing or hydrophilizing all or part of the remaining hydroxyl hydrogen atoms, or by conducting the hydrophobization and the hydrophilization simultaneously.

The introduction of the substituents can be conducted by, for example, reacting a polysaccharide or a polysaccharide derivative with an alkyl or alkenyl glyceidyl ether wherein the alkyl or alkenyl group has 8 to 40 carbon atoms, an epoxide, halide, halohydrin or acyl halide having a C.sub.8 -C.sub.40 linear or branched, saturated or unsaturated alkyl group, or an ester or carboxylic anhydride wherein the acyl group has 8 to 40 carbon atoms in the presence of an alkali to introduce the hydrophobic substituent (A) and thereafter reacting the obtained polysaccharide derivative with vinylsulfonic acid, or a haloalkanesulfonic or halocarboxylic acid or a halophosphate or halosulfate ester which has 1 to 5 carbon atoms and may be hydroxylated, or a salt thereof in the presence of an alkali.

The cementitious material to be used in preparing the gypsum-based adhesive composition of the present invention [i.e., the cementitious material to which the additive of the present invention containing the above polysaccharide derivative is added] is an inorganic substance which can be hardened when mixed with water. Such an inorganic substance is typically hemihydrate gypsum (calcined gypsum), though the substance is not limited to it. Here the hemihydrate gypsum refers to ones generally produced by calcining natural gypsum, phospho-gypsum, titano-gypsum or fuel gas gypsum at 110 to 120.degree. C.

The amount of the additive for gypsum-based adhesives to be added to a cementitious material may suitably be selected in accordance with the desired extents of thickening and adhesiveness. For example, it is preferable that the additive be used in an amount of 0.0001 to 0.03% by weight in terms of the polysaccharide derivative based on the cementitious material. Further, it is still preferable from the standpoint of the balance between adhesiveness and cost that the additive be used in an amount of 0.0005 to 0.01% by weight in terms of the polysaccharide derivative based thereon.

The addition of the additive to a cementitious material can be conducted in a state of any of aqueous solution and powder, and the addition may be conducted prior to the mixing of a gypsum-based adhesive, i.e., by dry blending with a cementitious material or dissolution in mixing water, or during the mixing of a gypsum-based adhesive, i.e., simultaneously with the addition of water to a cementitious material or between the completion of the addition of water and the completion of mixing of a gypsum-based adhesive. Alternatively, the additive may be added to a gypsum-based adhesive which has already been mixed. Further, the mode of addition may be any of the addition of the whole at once and the addition thereof in several portions.

The adhesive composition according to the present invention may further contain other various admixtures and/or additives. Such admixtures and additives include various fibrous reinforcements such as asbestos, glass fiber, polypropylene fiber, Vinylon fiber and aramide fiber, lightweight aggregates such as perlite and vermiculite, fillers such as blast furnace slag, fly ash, fumed silica, pulverized stone and silica sand, expanding admixture such as bentonite, surfactants such as plasticizer, retarder, and high-early-strength agent.

Embodiment 4

In the present invention, the polysaccharide derivative used as a thickener is described in the embodiment 3. The polysaccharide derivative exhibits a suitable solubility in mixing water and satisfactory thickening effects and therefore imparts excellent capability of plastering to mortar. With respect to the polysaccharide derivative to be used in this embodiment, it is therefore preferable that the degree of replacement by the hydrophobic substituent (A) be 0.0001 to 1, still preferably 0.0005 to 0.01 per constituent monosaccharide residue, and that by the ionic polar substituent (B) be 0.001 to 2, still preferably 0.01 to 1 per constituent monosaccharide residue. It is particularly preferable that the degrees of replacement by the substituents (A) and (B) be 0.0007 to 0.005 and 0.02 to 0.15 respectively.

The additive for mortar according to the present invention comprises the above polysaccharide derivative. The cementitious material to which the additive is added is an inorganic substance which can be hardened when mixed with water. Typical examples of such an inorganic substance include portland cement, blast-furnace slag cement and silica cement, though the substance is not limited to them.

The amount of the additive for mortar to be added to a cementitious material may suitably be selected in accordance with the desired extents of thickening and capability of plastering. For example, it is preferable that the additive be used in an amount of 0.0001 to 0.03% by weight in terms of the polysaccharide derivative based on the cementitious material. Further, it is still preferable in the balance between workability and cost that the amount be 0.0005 to 0.01% by weight in terms of the polysaccharide derivative based thereon.

The addition of the additive to a cementitious material can be conducted in a state of any of aqueous solution and powder, and the addition may be conducted either prior to the mixing of mortar, i.e., by dry blending with a cementitious material and fine aggregate or dissolution in mixing water, or during the mixing of mortar, i.e., simultaneously with the addition of water to a cementitious material or betwe