JP2602048B2 - Cement additives and compositions - Google Patents

Description

The present invention relates to cement additives and compositions. More specifically, the present invention relates to an additive comprising a cationic or amphoteric water-absorbing resin having a quaternary ammonium base as an essential component, and a cement composition containing the additive.

[Prior Art] Cement compositions consist of cement and, if necessary, sand, gravel, aggregate and other cement additives. The hardening phenomenon of this cement composition is due to the chemical hydration reaction between cement and water. is there. Generally, the strength of the cement product obtained by the hydration reaction increases as the water / cement ratio decreases. However, in order to secure workability (workability) during concrete casting, water /
It is the present situation that the ratio of cement is increased. As a result, there are problems in that extra time is required until setting, and that the volume is reduced due to the hydration reaction to cause cracks. For the purpose of solving such a problem, a method of adding a polyacrylate-based water-absorbing resin to a cement composition has been proposed (for example, JP-A-56-69257).

[Problems to be Solved by the Invention] However, in the above method, since the water-absorbing resin used is an anionic water-absorbing resin having a carboxyl group, the water-absorbing resin has high water absorbing power against deionized water and tap water. However, in the case of a polyelectrolyte solution containing a large amount of calcium ions, aluminum ions, and the like contained in cement, insolubilization proceeds due to ionic cross-linking, and the water absorbing power is extremely reduced. Therefore, in the method of adding the anionic water-absorbing resin, a large amount of the water-absorbing resin must be added in order to prevent the occurrence of cracks, which is problematic in terms of economy. In addition, after the concrete, which is a cement composition, is cast, a strongly alkaline inorganic substance having no binding force between particles containing a calcium compound as a main component floats on the concrete surface together with breathing water to form a sedimentary layer called latence. . If this latence is left, it will scatter from the concrete surface, and if it is inhaled by the human body and comes into contact with water, it will exhibit a strong alkalinity, which may harm health. In addition, when concrete is joined without removing the latencies, the new and old concretes are not integrated, causing cracks, water leakage, rusting of internal reinforcing bars, and the like, and may even lead to the destruction of structures. The conventional method of adding an anionic water-absorbing resin to a cement composition has not been effective enough to prevent the formation of laittance.

[Means for Solving the Problems] The present inventors have conducted intensive studies on cement additives and compositions that can prevent cracks at low cost and prevent the formation of latencies. The present invention has been reached. That is, the present invention is a cement additive comprising a cationic or amphoteric water-absorbing resin having a quaternary ammonium base, and a cement composition containing the additive.

In the present invention, examples of the cationic water-absorbing resin having a quaternary ammonium group include a cationic vinyl monomer having a quaternary ammonium group (A), a copolymerizable crosslinking agent (C), and a nonionic And a cationic water-absorbing resin obtained by polymerizing the water-soluble vinyl monomer (D).

In the present invention, examples of the amphoteric water-absorbing resin having a quaternary ammonium group include a cationic vinyl monomer having a quaternary ammonium group (A) and an anionic vinyl monomer having a carboxyl group and / or a sulfone group. The polymer (B), the copolymerizable crosslinking agent (C) and, if necessary, the nonionic water-soluble vinyl monomer (D) are polymerized, and if necessary, neutralized with an alkali metal compound to partially form an alkali metal base. And amphoteric water-absorbing resins.

Examples of the cationic vinyl monomer (A) having a quaternary ammonium base include a reaction product of a dialkylaminoalkyl (meth) acrylate with an alkyl halide or dialkyl sulfate [eg, (meth) acryloyloxyethyltrimethylammonium chloride or bromide, (Meth) acryloyloxyethyltrimethylammonium methyl sulfate, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxypropyltrimethylammonium chloride, etc.); The reactants [eg (meth) acryloyloxyhydroxyethyltrimethylammonium chloride or Myd, (meth) acryloyloxyhydroxyethyltrimethylammonium methyl sulfate, etc.]; a reaction product of dialkylaminoalkyl (meth) acrylamide with alkyl halide or dialkyl sulfate [eg, chloride or bromide of trimethylaminoethyl (meth) acrylamide, trimethylamino Propyl (meth) acrylamide chloride; a reaction product of dialkylaminohydroxyalkyl (meth) acrylamide with an alkyl halide or dialkylsulfuric acid [for example, trimethylaminohydroxyethyl (meth) acrylamide chloride, diethylmethylaminohydroxypropyl (meth) ) Chloride of acrylamide, etc.]; N-alkylvinylpyridinium halide [eg, N-methyl-2-vinylpyridinium chloride Or a bromide, N-methyl-4-vinylpyridinium chloride, etc.], a trialkylallylammonium halide [eg, trimethylallylammonium chloride, triethylallylammonium chloride, etc.]
And so on. These cationic vinyl monomers having a quaternary ammonium base may be used alone or in combination of two or more.

Examples of the anionic vinyl monomer (B) having a carboxyl group include unsaturated mono- or polycarboxylic acids [(meth) acrylic acid (refers to acrylic acid and / or methacrylic acid; the same description is used hereinafter), croton. Acid, sorbic acid, maleic acid, itaconic acid, cinnamic acid, etc.] and their anhydrides [maleic anhydride, etc.].

Examples of the anionic vinyl monomer (B) having a sulfone group include aliphatic or aromatic vinyl sulfonic acids [vinyl sulfonic acid, (meth) allyl sulfonic acid, vinyl toluene sulfonic acid, styrene sulfonic acid, etc.], (meth) Acrylic sulfonic acid [sulfoethyl (meth) acrylate,
Sulfopropyl (meth) acrylate] and (meth) acrylamidosulfonic acid [such as 2-acrylamido-2-methylpropanesulfonic acid].

These anionic vinyl monomers having a carboxyl group and / or a sulfone group may be used as a water-soluble salt. These salts include alkali metal salts (salts such as sodium, potassium and lithium), alkaline earth metal salts (salts such as calcium and magnesium), ammonium salts and amine salts (salts of alkylamine such as methylamine and trimethylamine). Triethanolamine;
Alkanolamines such as diethanolamine) and two or more of these. Preferred among these are the sodium and potassium salts.

The anionic vinyl monomers may be used alone or in combination of two or more. Of these, preferred are vinyl monomers having a carboxyl group.

If necessary, a nonionic water-soluble vinyl monomer (D) can be used in combination with the cationic vinyl monomer (A) and optionally the anionic vinyl monomer (B). For example, hydroxyethyl (meth) acrylate , Hydroxypropyl (meth) acrylate, (meth) acrylamide, vinylpyrrolidone and the like.

Examples of the copolymerizable crosslinking agent (C) include (1) a compound having at least two polymerizable double bonds and (2) a cationic vinyl monomer having one polymerizable double bond and / or Compounds having at least one group capable of reacting with the functional group of the anionic vinyl monomer are mentioned.

Examples of the compound (1) include di- or tri- (meth) yl of N, N-methylenebis (meth) acrylamide, polyols [ethylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol]. Acrylic esters, divinylbenzene, divinyltoluene, tetraallyloxyethane, diallyl phthalate, diallyl adipate and the like can be mentioned.

Examples of the compound (2) include an ethylenically unsaturated compound containing a quaternary ammonium base and / or a group reactive with a carboxyl group or a sulfone group, for example, a hydroxyl group, an epoxy group, an amino group or the like. For example, unsaturated compounds containing hydroxyl groups [such as N-methylol (meth) acrylamide] and unsaturated compounds containing epoxy groups [such as glycidyl (meth) acrylate] can be used.

Preferred among the copolymerizable crosslinking agents (C) are (1)
Particularly preferred are N, N-methylenebisacrylamide, ethylene glycol diacrylate, trimethylolpropane triacrylate and tetraallyloxyethane.

In the cationic water absorbing resin of the present invention, the amount of (A) is usually 70 based on the total molar amount of (A) and (C).
999.99%, preferably 90 to 99.9%. When the amount of (A) is less than 70%, the obtained resin has a low water absorbing power with respect to a polyelectrolyte solution, and thus is inferior in the performance of preventing cracks and preventing the formation of latencies.

The amount of (C) is usually from 0.01 to 10%, preferably from 0.1 to 5%, based on the total molar amount of (A) and (C).
When the amount of (C) is less than 0.01%, the obtained resin has a low gel strength when absorbing water and becomes a sol. On the other hand, if it exceeds 10%, on the contrary, the gel strength becomes too large, and the water absorbing power to the polyelectrolyte solution is reduced.

The amount of (D) used together if necessary is (A), (C)
And usually 0 to 30%, preferably 0 to 10%, based on the total molar amount of (D) and (D). If the amount of (C) exceeds 30%, the obtained resin will have a reduced water absorbing power with respect to the polyelectrolyte solution.

In the amphoteric water-absorbing resin of the present invention, the molar ratio of the cationic vinyl monomer (A) to the anionic vinyl monomer (B) varies depending on conditions such as required absorption performance and strength of the water-absorbing gel. But usually (A) :( B) = 85: 15-15:
85, preferably (A) :( B) = 70: 30 to 30:70.

The amount of the copolymerizable crosslinking agent (C) is usually based on the total molar amount of (A), (B) and optionally (D).
It is 0.01 to 10%, preferably 0.1 to 5%. When the amount of the copolymerizable crosslinking agent is less than 0.01%, the obtained resin has a low gel strength when absorbing water and becomes a sol. On the other hand, if it exceeds 10%, the gel strength becomes too high, and the water absorbing power to the polyvalent electrolyte solution decreases.

If necessary, the amount of the nonionic water-soluble vinyl monomer (D) is usually 30% or less, preferably 10% or less, based on the total molar amount of (A), (B), (C) and (D). % Or less.

The method of polymerizing the vinyl monomers (A) and (B), the copolymerizable crosslinking agent (C), and the optionally used nonionic vinyl monomer (D) is a conventionally known method. For example, a method of polymerizing these aqueous solutions or aqueous dispersions using a radical polymerization catalyst, a method of reverse phase suspension polymerization using an organic solvent, and a usual method of irradiating radiation, electron beam, ultraviolet light, and the like can be mentioned. Can be

In the present invention, a carboxyl group and / or a sulfone group may be neutralized by adding an alkali metal compound, if necessary, to partially form an alkali metal base.

Examples of the alkali metal compound include alkali metal hydroxides (such as sodium hydroxide, potassium hydroxide, and lithium hydroxide), alkali metal carbonates (such as sodium carbonate and sodium bicarbonate), and double or more thereof. Preferred among these are sodium hydroxide, potassium hydroxide and sodium bicarbonate.

The degree of neutralization is usually 90 mol% or less of carboxyl groups and / or sulfone groups, and preferably 50 to 80 mol%. If the degree of neutralization of the carboxyl group and / or the sulfone group exceeds 90 mol%, the pH of the obtained resin becomes high, which is problematic in terms of safety to human skin.

By further crosslinking with a compound having at least two groups capable of reacting with a functional group in the polymer, a resin having higher gel strength and more excellent stability of a water-absorbing gel can be produced.

Examples of the compound include a quaternary ammonium base, a carboxyl group, a sulfone group such as an epoxy group, a hydroxyl group, and an isocyanate group, and / or a functional group (eg, a hydroxyl group) of a nonionic water-soluble vinyl monomer used as required. Amide group) and a compound having at least two groups reactive with a polyvalent metal compound capable of forming an ionic cross-link.

Next, the polymer is dried and pulverized by a usual method, and if necessary, adjusted to a desired particle size to obtain a water-absorbent resin in the present invention.

The shape of the water-absorbent resin is not particularly limited, and may be any shape such as powder, granule, flake, and fiber.

The absorbency of the water absorbent resin is, for example, 10 g / g or more, preferably 15 g / g or more with respect to a 5% calcium chloride aqueous solution.

Organic powders [eg, cellulose derivatives, starch derivatives, sawdust, etc.] as fillers and fillers in the water-absorbent resin of the present invention; inorganic powders [eg, perlite, silica, diatomaceous earth, etc.]; Reactive resins [eg, cross-linked polyvinyl alcohol, cross-linked polyethylene oxide, cross-linked polyacrylate,
A crosslinked product of isobutylene-maleic anhydride copolymer, a crosslinked product of starch-acrylate copolymer, a saponified product of vinyl acetate- (meth) acrylate copolymer, etc.]. In addition, a thickener, a water reducing agent, an anti-whitening agent, a surfactant and the like can be used in combination, if necessary. The amount of these added is not particularly limited, and may be the amount usually used in combination.

In the present invention, examples of the cement include hydraulic cements such as ordinary Portland cement, mixed Portland cement, alumina cement, lime mixed cement, and slag cement. Special cements such as quick setting cements and high strength cements are also included in the present invention.

Aggregates to be blended as necessary include, for example, river sand,
In addition to common aggregates such as sea sand, gravel, and crushed stone, slag, shirasu, fly ash, asbestos, rock wool and the like can be mentioned. The amount of these aggregates is usually 50 to 1000 parts by weight based on 100 parts by weight of cement.

Other cement additives include water-soluble polymers [eg, cellulose derivatives such as methyl cellulose,
Polyvinyl alcohol etc.), synthetic resin emulsion [eg EVA emulsion, vinyl acetate emulsion etc.], natural or synthetic rubber latex [SBR latex etc.], organic sulfonic acid compound [sodium lignin sulfonate, sodium allyl sulfonate etc.], quick setting agent [For example, alkali aluminate and alkali carbonate alone or in a mixture, water glass type, calcium aluminate type quick setting agent, etc.], inorganic fiber [for example, glass fiber,
Known additives such as asbestos and rock wool] are appropriately used for the purpose of workability, adhesiveness, reinforcement and the like of the cement composition.

The compounding amount of these cement additives is usually 100% by weight or less, preferably 50% by weight or less based on the cement.

In the present invention, the amount of the cationic or amphoteric water-absorbing resin to be incorporated into the cement composition can be appropriately selected depending on the content of the cationic group, the water / cement ratio at the time of use, the type and amount of the aggregate, and the like. Against 0.01
-10% by weight, preferably 0.1-5% by weight. When the amount of the water-absorbing resin is less than 0.01% by weight, the prevention of cracks, the prevention of the formation of latencies and the like become incomplete. On the other hand, if it exceeds 10% by weight, the water / cement ratio will be too low, impairing the workability and disadvantageous economically.

There is no particular limitation on the method of blending the water-absorbent resin in the present invention into the cement composition. For example, the water-absorbent resin can be added to and mixed with the cement composition in a powder or water-swelled state, and the mixing apparatus is not particularly limited. . Normally, concrete is obtained by adding a predetermined amount of water to the cement composition and kneading the same. However, a water-absorbing resin may be added simultaneously with or after the addition of water.

EXAMPLES Hereinafter, the present invention will be further described with reference to Production Examples and Examples, but the present invention is not limited thereto. Parts in the production examples are parts by weight.

Production Example 1 (Production of cement additive) 22 parts of methacryloyloxyethyltrimethylammonium chloride, 8 parts of acrylic acid, 0.35 part of trimethylolpropane triacrylate and 70 parts of water were charged into an openable and closable container, and the liquid temperature was increased under a nitrogen atmosphere. To 15 ° C, 1 part of 0.5% ammonium persulfate aqueous solution and 0.5%
When 1 part of an aqueous solution of sodium hydrogen zincate was added and the mixture was polymerized, a gel was formed with heat generation. 5 from the start of polymerization
After a lapse of time, the closed container was opened, and the produced gel-like hydrous crosslinked polymer was taken out. This gel was cut into pieces, dried with a drum dryer heated to 150 ° C., and pulverized to a particle size of 32 to 145 mesh to obtain an amphoteric water-absorbent resin (a) as a cement additive of the present invention.

The amount of absorption in a 5% calcium chloride aqueous solution was 42 g / g.

Production Example 2 (Production of Cement Additive) In the above Production Example 1, 23.5 parts of methacryloyloxyethyldimethylbenzylammonium chloride and 6.5 parts of acrylic acid were used instead of 23.5 parts of methacryloyloxyethyltrimethylammonium chloride and 8 parts of acrylic acid. An amphoteric water-absorbent resin (b) as a cement additive of the present invention was obtained in the same manner as in Production Example 1 except that the amount of trimethylolpropane triacrylate was changed to 0.24 part. The amount of absorption in a 5% aqueous solution of calcium chloride was 45 g / g.

Production Example 3 (Production of Cement Additive) 30 parts of methacryloyloxyethyldimethylbenzylammonium chloride, 0.3 part of N, N-methylenebisacrylamide and 70 parts of water were charged in an openable and closable container. After the temperature was raised to 1 ° C., 1 part of a 0.5% aqueous solution of ammonium persulfate and 1 part of a 0.5% aqueous solution of sodium bisulfite were added and polymerized. After 5 hours from the start of the polymerization, the sealed container was opened, and the produced gel-like hydrous crosslinked polymer was taken out. This gel was cut into pieces, dried with a drum dryer heated to 150 ° C., and pulverized to a particle size of 32 to 145 mesh to obtain a cationic water-absorbent resin (c) as a cement additive of the present invention. . The amount of absorption in a 5% calcium chloride aqueous solution was 38 g / g.

Examples 1 to 4 1000 g of ordinary Portland cement, 5500 g of aggregate (mixture of river sand and gravel) and a predetermined amount of a water-absorbent resin (a), (b) or (c) as a cement additive in the present invention were previously mixed. To obtain the cement composition of the present invention. Further, the concrete adjusted by adding water and kneading well so that the water / cement ratio becomes 55% is adjusted to a diameter of 15 cm and a height of 30 cm.
cm in a cylindrical formwork, and then indoors for 24 hours (temperature: 18
(22 ° C., humidity; 60-70% RH) and allowed to congeal, and then the mold was removed and observed for the occurrence of laittance. Further, the cement composition was exposed outdoors for a predetermined time, and the strength of the cement composition was measured over time. Table 1 shows the results.

Comparative Examples 1 to 3 Comparative Examples 1 to 3 without water-absorbent resin, commercially available anionic water-absorbent resin "Aquakeep 10SH" (Steel Chemical Industry Co., Ltd., crosslinked sodium polyacrylate, absorption amount of 5% calcium chloride aqueous solution) 5g / g) or "Sumikagel SP-51"
0 "(Sumitomo Chemical Co., Ltd., saponified bi-acrylate-acrylate copolymer, 5% calcium chloride aqueous solution absorption 8g
/ g) was used in Comparative Example 2
Table 1 also shows Comparative Example 3 as well.

Concrete strength in Examples and Comparative Examples is JIS
It was measured based on A-1108. Microscopic observation of the occurrence of surface cracks after standing for 6 months revealed that no cracks were observed in Examples 1 to 4 of the present invention. On the other hand, cracks were clearly observed in Comparative Example 1, and slight cracks were also observed in Comparative Examples 2 and 3.

[Effect of the Invention] When the cement additive and the composition of the present invention are used, the following effects are exerted.

(1) Latitude generation can be suppressed.

Normally, when concrete is poured, an inorganic substance that has no binding force between particles mainly composed of polyvalent metals such as calcium, aluminum, and silicon elutes on the concrete surface together with breathing water from immediately after casting until the solidification is completed. It dries and deposits an alkaline latence on the surface.

Cationic or amphoteric water-absorbing resin having a quaternary ammonium base which is a component of the cement additive of the present invention,
Since the strong alkaline solution in which the polyvalent metal ions are dissolved is absorbed and held in the concrete, there is almost no generation of latencies. Therefore, when the cement additive or the composition of the present invention is used, there is no fear that human health is harmed due to scattering of the latence deposited on the concrete surface, and a concrete product having an excellent appearance can be obtained.

In addition, there is no need to worry about latency removal work when new and old concrete are to be handed over, which leads to a reduction in labor and a shortened construction period.

(2) The time until solidification can be reduced.

Since the water-absorbent resin in the additive absorbs excess water and moderately lowers the water / cement ratio, the time required for setting to be completed is reduced. Also, the time required to reach the predetermined strength is short.

(3) The strength of the concrete product is improved.

As described above, as a result of appropriately reducing the water / cement ratio, the strength of the obtained product is improved.

(4) No need for moist curing at the beginning of construction.

Since the hydrogel contained in the concrete acts as a humectant, the usual wet curing can be omitted.

(5) The amount of water-absorbing resin used is small and economical.

The anionic water-absorbing resin used in conventional cement additives shows high water absorption to deionized water and tap water, but contains as much Ca2 ⁺ and ionic Al3 ⁺ ions as concrete water. For a solution containing a large amount of valent metal ions and strongly alkaline solution, the insolubilization of the resin progresses due to ionic cross-linking, resulting in extremely low water absorption power and poor stability of the water-absorbing gel. It was necessary to use a conductive resin.

However, the cationic or amphoteric water-absorbing resin having a quaternary ammonium base in the present invention has a high water-absorbing power to a high-concentration polyvalent electrolyte solution or a strongly alkaline solution, and is also excellent in stability of a water-absorbing gel. Therefore, excellent effects can be obtained with a small amount of use, which is economical.

Because of the above effects, the cement additive and the composition of the present invention can be used for placing concrete at a construction site; concrete paving surface; box culvert slab surface; precast plate, pile, block, U-shaped groove, shield segment and the like. The present invention is effective in any situation where a cement additive and a composition are required, such as in the production of concrete products;

Claims (5)

(57) [Claims] 1. A cement additive comprising a cationic or amphoteric water-absorbing resin having a quaternary ammonium base. 2. The method according to claim 1, wherein said cationic water-absorbing resin is a cationic vinyl monomer having a quaternary ammonium base (A), a copolymerizable crosslinking agent (C), and optionally a nonionic water-soluble vinyl monomer. The additive according to claim 1, which is a cationic water-absorbing resin obtained by polymerizing (D). 3. An amphoteric water-absorbing resin comprising: a cationic vinyl monomer having a quaternary ammonium group (A); an anionic vinyl monomer having a carboxyl group and / or a sulfone group (B); An amphoteric water-absorbing resin obtained by polymerizing a water-soluble cross-linking agent (C) and, if necessary, a nonionic water-soluble vinyl monomer (D) and, if necessary, neutralizing with an alkali metal compound to partially form an alkali metal base. Item 8. The additive according to Item 1. 4. A cement composition comprising cement and, if necessary, aggregate and other cement additives,
Or a cement composition containing the additive according to 3 above. 5. The composition according to claim 4, wherein the additive according to claim 1, 2 or 3 is incorporated in an amount of 0.01 to 10% by weight based on the cement.