JPH03131553A - Improved cement composition and production thereof - Google Patents

Abstract

PURPOSE:To obtain a cement composition having high forming stability and high water retaining property together by kneading a cement with water and an emulsified copolymer containing an alpha,beta-monoethylenic unsaturated carboxylic acid. CONSTITUTION:When a cement is blended and kneaded with water and a high polymer compound or a cement is blended and kneaded with water, an aggregate and a high polymer compound to provide the aimed cement composition, the blending and kneading is carried out as follows: An emulsified copolymer containing an alpha,beta-monoethylenic unsaturated carboxylic acid as a monomer is used as the above-mentioned high polymer compound. In the above-mentioned emulsified copolymer, especially a monomer having at least two alpha,beta-ethylenic unsaturated double bonds in the molecule works as crosslinking ingredient, increases molecular weight of the emulsified copolymer itself and forms three- dimensional structure and moreover improves viscous property and water retaining property. Methacrylic acid is especially preferably used as an alpha,beta- monoethylenic unsaturated carboxylic acid.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has particularly excellent molding stability, and furthermore,
The present invention relates to a new and useful cement composition with high water retention and a method for producing the same. More specifically, it is particularly effective for "deformation" during demolding, which consists of adding and blending cement, water, and if necessary aggregate, and a specific emulsifying copolymer as a polymeric compound as an additive component. The present invention relates to a general and improved cement composition and a method for producing the same, which have fewer troubles such as "dryout" and can improve the operating rate of formwork.

[Conventional technology]

Cement mortar (also called single mortar6) molded products and cement concrete (simply called concrete,
) The biggest problem in manufacturing various cement molded products such as molded products is how to quickly demold the cement molded products and improve the operating rate of the formwork.

However, if the demolding is done in such a hurry that the cement composition itself is not sufficiently hardened, the mold is removed from the mold.
Inevitably, the molded product gradually deforms due to its own weight, and the corners of the molded product become rounded, making it difficult to obtain a molded product with the desired shape, resulting in poor molding stability. Furthermore, since the cement composition still contains a large amount of so-called free water, which has not yet been incorporated into the curing reaction of the cement composition, the problem of "dryout" is likely to occur.

Therefore, various countermeasures have been taken to solve these drawbacks and difficulties.

For example, by reducing the amount of water used in cement as much as possible, such as immediate demolding concrete and extrusion concrete, we can create a cement composition that is hard enough to not deform even if it is demolded immediately after molding. There is a way to get it.

However, when such a method is followed, it is difficult to adjust and adjust the water ratio, etc., and when water scatters due to dryout, the cement becomes unhardened, and the corners of the molded product are likely to be damaged. Ta.

There is also a method of accelerating the hardening reaction of the cement composition by using early-strength (early-hardening) cement or cement quick-setting agents, or by means such as steam curing or autoclave curing. However, in general, there are problems such as high raw material costs and large-scale equipment, and disadvantages such as cranking and distortion due to rapid acceleration of cement hardening. .

Furthermore, by incorporating methylcellulose as a polymeric compound as an additive component into cement, the viscosity and water retention of so-called cement mixtures such as cement paste, cement mortar, or cement concrete can be increased. Although there are ways to prevent molded products from deforming or drying out due to their own weight,
This method cannot be expected to be very effective in very small doses;
On the other hand, when used in large amounts, the negative effect of delaying the hardening of the cement itself becomes significant, and furthermore, the cement mixture tends to entrain air.

In addition, such methods require that methylcellulose itself has poor solubility in water or miscibility in cement formulations;
Therefore, there was also a drawback that the cement mixture was not uniformly mixed.

[Problem that the invention seeks to solve]

In this way, the mold can be removed quickly, and it is free from problems such as poor molding stability and dryout.
Although extremely useful cement compositions and methods for their production are in particular demand at present,
Unfortunately, this could not be achieved using conventional technology.

Therefore, the problem to be solved by the present invention is to gel in an alkaline atmosphere and exhibit extremely high water retention, and in addition, due to the action of the high water retention, it causes problems such as deformation and dryout during demolding. The purpose is to provide a cement composition with a novel form that is free from the troubles of
Another object of the present invention is to provide a method for producing a cement & II product that has both high molding stability and high water retention.

[Means to solve the problem]

Therefore, the present inventors set their sights on the problems to be solved by the invention as described above.In particular, the present inventors achieved excellent molding stability and water retention during demolding, and as a result, the utilization rate of the formwork was improved. As a result of extensive research in order to obtain a novel type of cement composition that can improve the
For the first time, we have found an extremely useful cement composition and a method for producing the same that can simultaneously solve the pending problems of high molding stability and high water retention, and have completed the present invention.

That is, the present invention provides a cement composition consisting of cement, water, and a polymer compound, or a cement composition consisting of cement, water, aggregate, and a polymer compound. An object of the present invention is to provide an extremely useful cement composition that uses an emulsion copolymer containing ethylenically unsaturated carboxylic acid as an essential monomer, and which has improved molding stability and water retention at the same time. In addition, in a method for producing a cement composition by blending and kneading such cement, water, and a polymer compound, or cement, water, aggregate, and a polymer compound, such a polymer compound As described above, the emulsion copolymer having α,β-monoethylenically unsaturated carboxylic acid as an essential monomer is used, and in particular, both molding stability and water retention are improved. The present invention also aims to provide a novel method for producing a cement composition.

In the present invention, the term "cement paste J" refers to a mixture of cement and water, and the term "cement mortar" mentioned above refers to a mixture of cement, water, and aggregate. Among these, this term particularly refers to cement formulations in which such aggregate components have relatively small particle sizes called "fine aggregates," and further,
The above-mentioned term "cement concrete" refers to cement mixtures consisting of cement, water, and aggregates.
This designation refers to a compound in which the aggregate component has a relatively large particle size called "coarse aggregate".

First, the emulsion copolymer described above is used as one of the additive components for cement, and in particular, it gels in an alkaline atmosphere and imparts viscosity and water retention to the cement composition. It is a type of polymer compound mainly used for the purpose of preventing both troubles such as mold slippage and dry-out phenomenon during demolding.

In order for the emulsion copolymer itself to be kneaded in a cement formulation to fulfill all of the unique purposes mentioned above and to maximize the outstanding effects mentioned above,
It requires the use of a specific amount of α,β-monoethylenically unsaturated carboxylic acid, and more preferably such a specific amount of α.

Besides the use of β-monoethylenically unsaturated carboxylic acids,
It is also essential to use a monomer having at least two α,β-ethylenically unsaturated double bonds in the molecule.

That is, the emulsion copolymer contains a specific amount of α, β.
- copolymers of monoethylenically unsaturated carboxylic acids with other α,β-ethylenically unsaturated monomers, inter alia, particular amounts of such α,β-monoethylenically unsaturated carboxylic acids; and a copolymer of a monomer having at least two α,β-ethylenically unsaturated double bonds and another α,β-ethylenically unsaturated monomer.

In particular, the jKffi compound (hereinafter abbreviated as polyfunctional monomer) having at least two α,β ethylenically unsaturated double bonds in its molecule acts as a crosslinking component and binds the emulsion copolymer to the emulsion copolymer. Increase its own molecular weight and make it three-dimensional,
This further improves viscosity and water retention.

In addition, in order for the emulsion copolymer itself to easily diffuse in the cement composition and exhibit the maximum effect after gelling, it must have a particle size within a specific range. It needs to be an aqueous dispersion.

Typical α,β-monoethylenically unsaturated carboxylic acids used in preparing the emulsion copolymer include (meth)acrylic acid, crotonic acid, and itaconic acid. acid, maleic acid or fumaric acid, or monoesters of unsaturated dicarboxylic acids such as maleic acid or fumaric acid with monohydric alcohols, among others, acrylic acid or methacrylic acid, particularly preferably methacrylic acid. It is an acid.

Such α,β-monoethylenically unsodated carboxylic acids may be used alone or in combination of two or more types, and the amount used is preferably within the range of 30 to 70% by weight based on the total monomers. is suitably within the range of 50 to 70% by weight.

If it is less than 30% by weight, the resulting emulsion copolymer will not have sufficient water retention performance;
If it exceeds % by weight, the copolymerizability with other monomers
In either case, it is not preferable because it inevitably becomes worse.

In addition, to exemplify only particularly representative polyfunctional monomers having at least two α,β-ethylenically unsaturated double bonds in the molecule, divinylbenzene , divinyltoluene, divinylxylene,
Divinyl compounds such as divinyl ether or divinyl ketone; diester compounds of unsaturated carboxylic acids and polyols such as di(meth)acrylic acid esters of mono-, di- or triethylene glycol; diallyl fumarate, diallyl maleate or diallyl esters of unsaturated dicarboxylic acids such as diallyl phthalate; or difunctional monomers such as diene compounds such as butadiene or hexadiene; or trimethylolethanetri(meth:acrylate or trimethylolpropane tri(meth)acrylate, etc.) trifunctional monomers; and tetrafunctional monomers such as tetraacryloxyethane or pentaerythritol tetra(meth)acrylate; however, when copolymerizability and economic efficiency are considered, Particular preference is given to using divinylbenzene, divinyltoluene, ethylene glycol di(meth)acrylate, diallyl maleate or diallyl phthalate.

The appropriate amount of the polyfunctional monomer to be used is 0.05 to 5% by weight, preferably 0.1 to 3% by weight based on the total monomers. .

If the amount is less than 0.05% by weight, the emulsion copolymer will not have sufficient thickening properties and water retention properties; on the other hand, if it exceeds 5% by weight, it will not be sufficient. If this is the case, the copolymerizability may be lowered or gelation may easily occur during polymerization, which is not preferable in either case.

Furthermore, other monomers copolymerizable with the above-mentioned α,β-monoethylenically unsaturated carboxylic acids and polyfunctional monomers include (meth)acrylic acid alkyl esters. The ones with low solubility in water are good.
Among them, to exemplify only the most representative ones, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, (isobutyl methacrylate, ) such as 2-ethylhexyl acrylate or stearyl (meth)acrylate (
meth)acrylic acid alkyl esters; aromatic vinyl monomers such as styrene, α-methylstyrene, α-halostyrene, vinyltoluene or vinylnaphthalene; vinyl esters such as vinyl acetate, vinyl butyralate or vinyl persatate; methyl vinyl ether , ethyl vinyl ether, propyl vinyl ether or hexyl vinyl ether; or various so-called reactive polar-free vinyl monomers such as (meth)acrylonitrile, maleic dinitrile or vinyl cyanides such as vinylidene dicyanide; Alternatively, it is a variety of vinyl monomers containing so-called reactive polar groups, such as glycidyl (meth)acrylate or glycidyl compounds such as allyl glycidyl ether.

In addition, various silane compounds such as vinyltrichlorosilane, vinylethoxysilane, vinyltris(β-methoxyethoxy)silane or γ-methacryloyloxypropyltrimethoxysilane; (meth)acrylamide, N-methylol(meth) Various amide compounds such as acrylamide or diacetone acrylamide or their alkoxide derivatives;
Various hydroxyl group-containing compounds such as β-hydroxyethyl (meth)acrylate, β-hydroxypropyl (meth)acrylate or β-hydroxybutyl (meth)acrylate; or N.

Other types of vinyl monomers containing reactive polar groups, such as various amine-based compounds such as alkylamino (meth)acrylates such as N-dimethylaminoethyl (meth)acrylate or N,N-diethylaminoethyl (meth)acrylate. These monomers also function as crosslinking monomers by reacting with such reactive polar groups, exerting the same effect as the polyfunctional monomers listed above. It is something to do.

These other copolymerizable monomers may be used alone or in combination of two or more types, and the amount used is, based on the total monomers,
30 to 70% by weight, preferably 30 to 5% by weight
A weight range of 0% weight is appropriate.

The emulsion copolymer is prepared by a known and commonly used emulsion polymerization method using the various monomers listed above, and of course, known and commonly used emulsifiers may be used. Various anionic emulsifiers such as sodium dodecylbenzene sulfonate, sodium lauryl sulfate or alkylaryl polyether sulfate; or polyoxyethylene lauryl, to name only the most representative ones. These include various nonionic emulsifiers such as ether and polyoxyethylene nonylphenyl ether, and these may be appropriately selected and used.

In addition, examples of the polymerization initiator used in obtaining the emulsion copolymer include water-soluble polymerization initiators, oil-soluble polymerization initiators, redox polymerization initiators, etc.
First of all, typical examples of water-soluble polymerization initiators include hydrogen peroxide, potassium persulfate, and ammonium persulfate. Also included are so-called redox initiators, which are formed in combination with suitable reducing agents such as sulfoxylates.

On the other hand, only typical examples of oil-soluble polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2-azobis(4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobisisobutyronitrile. ), azo compounds such as 2,2' azobis-2,4-dimethylvaleronitrile or 1,2'-azobis-cyclohexane-1-carbonitrile;
or peroxides such as benzoyl peroxide, lauroyl peroxide, dibutyl peroxide, diacetyl peroxide, dibropionyl peroxide or chthone hydroperoxide.

In addition, in preparing the emulsion copolymer, a chain transfer agent may be used to adjust the molecular weight.

Examples of suitable chain transfer agents include monohydric alcohols in which the alkyl group has 1 to 8 carbon atoms; alkyl mercaptans in which the alkyl group has 1 to 8 carbon atoms; or O-mercaptobenzoic acid or mercaptoacetic acid. It is.

Preferably, a redox initiator is used.

The appropriate polymerization temperature is within the range of 30 to 90°C, preferably within the range of 40 to 80°C.

The solid content concentration of the emulsion copolymer thus obtained is within the range of 10 to 50% by weight, preferably 20% by weight.
A range of 40% by weight is appropriate, and it is adjusted within this range for practical use.

Further, the pH of the emulsion copolymer should be adjusted to and maintained at 5 or less, especially considering the emulsion stability.

The particle size of the emulsion copolymer is 0.05 to 0.3.
The range of μm is preferably 0.05 to 0.2 μm.
It is appropriate that the emulsion copolymer is within the range of , where the particle size is 0.05μ
If the emulsion copolymer is smaller than m, the storage stability of the emulsion copolymer will inevitably be poor, and moreover, it will gel immediately during blending, resulting in a "sticky" consistency, and as a result, kneading will likely be insufficient. On the other hand, if it is too large, exceeding 0.3 μm, gelation itself tends to be insufficient, which is not preferable.

Next, typical examples of cement include ordinary Portland cement, early strength - 1 very early strength - 1 medium heat - or white Portland cement, fly ash cement, or silica cement, but even when used alone, two or more types of cement are used. Of course, it is also possible to use them together.

Furthermore, aggregates that can be used as necessary include river sand,
Typical examples include sea sand, mountain sand, fly ash, and crushed stone, which may also be used alone or in combination of two or more types.

In addition, various additives such as materials conventionally used in cement molded products, such as cement quick setting agents, defoaming agents, cement retarders, foaming agents, fluidizing agents, shrinkage reducing agents, or swelling agents, are added. agents; various lightweight aggregates such as expanded polystyrene beads or perlite; or various fiber reinforcement materials such as carbon fibers, glass fibers or nylon fibers; or various organic- or inorganic pigments; There is no problem in using it as long as it does not deviate from its effectiveness.

By the way, when discussing the formulation in the cement composition of the present invention, first, the amount of the above-mentioned emulsion copolymer used is 0 in terms of solid content relative to cement.
．． The proportion of 0.02 to 1% by weight is preferably 0.05
A ratio of ~0.5 is appropriate.

If 0.02% by weight is ungrooved, sufficient viscosity and water retention cannot be ensured, and on the other hand,
If too much is used, exceeding 1% by weight, it will inevitably delay the hardening of the cement.
In any case, not only is it undesirable, but since a sufficient effect can be achieved within the above-mentioned usage amount range, excessive use is also economically unfavorable.

Next, the amount of water used is 20~
A range of 100% by weight, preferably a range of 30 to 70% by weight is appropriate, but it is appropriately selected and determined depending on the blending ratio in the cement composition, the method of manufacturing cement molded products, etc.

Furthermore, the amount of aggregate used is 0 compared to cement.
~1.500% by weight, preferably 20% by weight
A range of 0 to 700% by weight is appropriate.

However, other than the amount of emulsion copolymer used, i.e.
It should be understood that the regulations regarding the amounts of water, aggregate, etc. to be used are by no means specific to the present invention, and are provided for reference only.

Examples of kneading methods for the cement composition of the present invention include:
(1) First, there is a method of kneading cement and water, and if necessary, aggregate with a mixer etc., and then adding and kneading the emulsified copolymer.
) There is also a method of first dissolving and dispersing the emulsified copolymer using all or part of the water used for mixing, and then kneading the cement and, if necessary, the aggregate.

However, the only difference is that cement, water, emulsion copolymer, and, if necessary, aggregate are added together and kneaded. Both are undesirable as diffusion becomes insufficient and should be avoided.

Preferably, method (2) described above is preferred.

As the molding method, any known and commonly used method can be applied.

In addition, it is preferable to use a combination with conventional techniques or methods that can increase the operating rate of the formwork, such as instant demolding concrete or extruded concrete, steam curing, or the use of a cement quick setting agent.

In particular, when the manufacturing method of the present invention is applied to instant demolding concrete, water retention is increased, and in addition, there is no dryout, resulting in a smooth and beautiful surface finish. In addition, even if the water ratio is slightly high, if the manufacturing method of the present invention is followed, it will also have the effect of preventing "bleed", a phenomenon in which surplus water that does not contribute to the hydration reaction of cement floats to the surface of the compound. Since it is expensive and has excellent molding stability, it can compensate for the shortcomings of the instant demolding concrete method.

〔Effect of the invention〕

As described above, the present invention improves both molding stability and water retention, which were problems in the past, by adding and blending a specific emulsion copolymer during the production of cement molded products. Furthermore, we have created an extremely useful cement composition that can improve the operating rate of formwork.
The present invention also provides a method for producing a cement composition that has these excellent characteristics.

Therefore, the main feature of the present invention is that a specific emulsion copolymer is
By simply adding and blending the appropriate amount, many of the excellent effects mentioned above can be achieved, no special equipment or construction methods are required, and there is no negative impact on the physical properties of cement molded products. The point is that it does not affect

Furthermore, it is a further aspect of the present invention that when using an emulsion copolymer with a specific particle size, not only the miscibility in cement but also the effect after blending is enhanced. This is one of the characteristics.

〔Example〕

Next, the present invention will be explained by reference examples, examples, and comparative examples.
The layer will be explained in detail. 1, ~ parts and % below
Unless otherwise specified, all are based on weight.

Reference Example 1 (Preparation example of emulsion copolymer) In a stainless steel reaction vessel equipped with a stirrer, reflux condenser, dropping funnel and thermometer, 140 parts of ion-exchanged water, [
12 parts of Lebenol WZJ (anionic emulsifier manufactured by Kao ■), 5 parts of Neugen EA170SJ (nonionic emulsifier manufactured by Dai-Kogyo Seiyaku), and the monomers in the composition ratios shown in Table 1. The mixture was stirred and emulsified in a nitrogen stream, and the temperature was raised to 40°C.

Next, 0.5 part of ammonium persulfate, 0.5 part of sodium sulfite, and 0.1 part of a 1% aqueous ferrous ion solution were added to initiate the polymerization reaction.

After the internal temperature reached the maximum temperature, the temperature was adjusted to 70°C, 0.5 parts of ammonium persulfate and 0.5 parts of sodium sulfite were added, and the temperature was maintained for 1 hour before the polymerization reaction was started. Completed.

Thereafter, the mixture was cooled to room temperature and the solid content was adjusted to 35%, yielding the desired emulsion copolymer. Hereinafter, this will be abbreviated as emulsion copolymer (A-1).

Reference Examples 2-4 Target emulsion copolymers (A-2)- (A-4) was obtained.

/ ? -No.1--Each person *Submicron particle size analyzer (Call Counter■) This is the value measured at .

Using the emulsion copolymers (A-1) to (A-4) obtained in Examples 1 to 4 and Comparative Examples 1 and 2 and Reference Examples 1 to 4 and methylcellulose, the following combinations were made:
Various cement compositions were prepared.

Note 1) River sand produced in Ibi, 2) Crushed stone produced in Takarazuka, 3) Adjusted to have an air content of 3 to 5%. The aggregate and methyl cellulose were dissolved and mixed in kneading water to a concentration of 0.15% in terms of solid content.

As a comparative example, in addition to this example of using methylcellulose (Comparative Example 1), an example in which neither the emulsion copolymer nor methylcellulose was used at all (Comparative Example 2) was also conducted.

Next, for each of the cement compositions obtained in this way, the molding stability and water retention when demolded in a state where the hardening is still insufficient, and the physical strength of the cured product in a sufficiently hardened form were evaluated. A comparative study was conducted.The results are summarized in Table 2.

However, the details of the various tests are as follows.

That is, first, each cement mixture was
Packed into a mold with a size of 0x10x40 and heated at 20°C at 60°C.
After curing for 6 hours under conditions of %R,H, the molds were demolded and molding stability and water retention tests were conducted.

In addition, the compressive strength test was conducted using a cylindrical mold with a diameter of 10 cm and a length of 20 cm, molding was performed under the above conditions, and the mold was removed after 12 hours.
This was done by measuring the amount of food that had been cured for one day.

First of all, the molding stability test was conducted using 10XI 0X4.
The molded body Qcm+ was left for 18 hours with the xoxiocI11 side as the bottom surface, and the ratio of the shrinkage rate in the vertical direction to the actual shrinkage height, that is, when this shrinkage height was defined as "X", ( The ratio was determined by measuring the ratio: 40-X)/40.

Next, the criteria for determining water retention are as follows, but mainly the presence or absence of bleeding, drying cracks, etc. is visually determined.

Breed Komakura/Ishihisa
O... Not at all The value of compressive strength was determined by the average value for three specimens.

/ / As is clear from Table 2, the cement composition of the present invention to which a specific emulsifying copolymer is added is superior in all applied physical properties.

Claims (1)

[Claims] 1. In a cement composition consisting of cement, water, and a polymer compound, or consisting of cement, water, aggregate, and a polymer compound, as the polymer compound,
An improved cement composition characterized by using an emulsion copolymer containing α,β-monoethylenically unsaturated carboxylic acid as an essential monomer. 2. The emulsion copolymer described above contains the α,β-monoethylenically unsaturated carboxylic acid in an amount of 30 to 70% by weight in the total monomers.
2. The cement composition according to claim 1, which is obtained by emulsion copolymerizing a monomer mixture comprising a monomer mixture within the range shown in FIG. 3. The cement composition according to claim 1, wherein the emulsion copolymer has a particle size of 0.05 to 0.3 μm. 4. The emulsion copolymer described above contains the α,β-monoethylenically unsaturated carboxylic acid and a monomer having at least two α,β-ethylenically unsaturated double bonds in the molecule, respectively. , 30-70% by weight in the total monomers and 0
．． 2. The cement composition according to claim 1, which is obtained by emulsion copolymerizing a monomer mixture containing 0.05 to 5% by weight. 5. The emulsion copolymer described above is applied to the cement,
The cement composition according to claim 1, wherein the cement composition is used at a solid content of 0.02 to 1% by weight. 6. In a method for producing a cement composition by blending and kneading cement, water, and a polymer compound, or by blending and kneading cement, water, aggregate, and a polymer compound, as the polymer compound, An improved method for producing a cement composition, characterized in that it uses an emulsion copolymer containing α,β-monoethylenically unsaturated carboxylic acid as an essential monomer. 7. The emulsion copolymer described above contains the α,β-monoethylenically unsaturated carboxylic acid in an amount of 30 to 70% by weight in the total monomers.
7. The manufacturing method according to claim 6, which is obtained by emulsion copolymerizing a monomer mixture comprising a monomer mixture within the following range. 8. The manufacturing method according to claim 6, wherein the emulsion copolymer has a particle size of 0.05 to 0.3 μm. 9. The emulsion copolymer described above contains the α,β-monoethylenically unsaturated carboxylic acid and a monomer having at least two α,β-ethylenically unsaturated double bonds in the molecule, respectively. , 30-70% by weight in the total monomers and 0
．． 7. The production method according to claim 6, which is obtained by emulsion copolymerizing a monomer mixture containing 0.05 to 5% by weight. 10. The manufacturing method according to claim 6, wherein the emulsion copolymer is used in a solid content of 0.02 to 1% by weight based on the cement.