CA1340500C - Water absorbent polymer and method of production thereof - Google Patents
Water absorbent polymer and method of production thereofInfo
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- CA1340500C CA1340500C CA000616396A CA616396A CA1340500C CA 1340500 C CA1340500 C CA 1340500C CA 000616396 A CA000616396 A CA 000616396A CA 616396 A CA616396 A CA 616396A CA 1340500 C CA1340500 C CA 1340500C
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Abstract
Water absorbent polymer capable of keeping absorbed water therein in the form of independent grains and having the property of slipping between particles is produced by:
a) dissolving acrylic copolymer as dispersing agent in a liquid aliphatic hydrocarbon; b) partially neutralizing an acrylic acid monomer in aqueous solution with an alkali to form an aqueous solution of partially neutralized acrylic acid; c) dispersing the aqueous solution of partially neutralized acrylic acid of b) in the solution of acrylic copolymer of a) to polymerize by w/o suspension polymerization; and d) subjecting the resultant polymer of c) to crosslinking reaction in the presence of crosslinking agents and in the presence or absence of an inorganic compound to dry.
a) dissolving acrylic copolymer as dispersing agent in a liquid aliphatic hydrocarbon; b) partially neutralizing an acrylic acid monomer in aqueous solution with an alkali to form an aqueous solution of partially neutralized acrylic acid; c) dispersing the aqueous solution of partially neutralized acrylic acid of b) in the solution of acrylic copolymer of a) to polymerize by w/o suspension polymerization; and d) subjecting the resultant polymer of c) to crosslinking reaction in the presence of crosslinking agents and in the presence or absence of an inorganic compound to dry.
Description
1~115~3 This is a divisional application of copending application S96,790, filed April 14, 1989.
This invention relates to a method for the production of fine grain ice or dry clathrate water for manufacture of concrete/mortar, a method for the production of concrete/mortar by using fine grain ice or dry clathrate water and concrete/mortar products manufactured by the method. Fine grain ice and dry clathrate water for manufacturing concrete/mortar produced by this invention are used when concrete/mortar is manufactured by the use of a small amount of water.
Thus, concrete/mortar can now be easily manufactured by making use of fine grain ice or dry clathrate water at a place where it is difficult to supply water.
In the case where concrete/mortar is manufactured by a conventional method, much more water is used than the amount of water necessary for hydration of cement in order to uniformly mix and temper the cement and water and to keep good flowability as well. However, there is a disadvantage in this method in that the strength and durability of the concrete/mortar after solidification are lower than the concrete/mortar produced by use of the amount of water close to the theoretical hydration quantity.
For this reason, the technique to mix cement or cement _ _ . . ... . . . .....
1340~00 and aggregate with fine grain ice instead of water has been studied. The features are as follows.
1) Since a powder mixture can be prepared with the cement, mixing can be performed at a low water/cement ratio.
This invention relates to a method for the production of fine grain ice or dry clathrate water for manufacture of concrete/mortar, a method for the production of concrete/mortar by using fine grain ice or dry clathrate water and concrete/mortar products manufactured by the method. Fine grain ice and dry clathrate water for manufacturing concrete/mortar produced by this invention are used when concrete/mortar is manufactured by the use of a small amount of water.
Thus, concrete/mortar can now be easily manufactured by making use of fine grain ice or dry clathrate water at a place where it is difficult to supply water.
In the case where concrete/mortar is manufactured by a conventional method, much more water is used than the amount of water necessary for hydration of cement in order to uniformly mix and temper the cement and water and to keep good flowability as well. However, there is a disadvantage in this method in that the strength and durability of the concrete/mortar after solidification are lower than the concrete/mortar produced by use of the amount of water close to the theoretical hydration quantity.
For this reason, the technique to mix cement or cement _ _ . . ... . . . .....
1340~00 and aggregate with fine grain ice instead of water has been studied. The features are as follows.
1) Since a powder mixture can be prepared with the cement, mixing can be performed at a low water/cement ratio.
2) Slump loss in proportion to the passage of time is small after mixing.
3) The temperature of mass concrete can be easily controlled.
In the case where this concrete mixing technique is actually applied, however, it is necessary to manufacture fine grain ice and this method presents a problem. In the conventional method, fine grain ice is obtained by crushing an ice block. In the case where fine grain ice is obtained by crushing an ice block, the defects are as follows.
1 ) In the case where a large amount of fine grain ice is needed, a big plant equipped with special devices such as an ice crusher and a slicer is necessary.
2) Fine grain ice must be kept at low temperature until it is used and an ice storage unit is necessary to do so.
Therefore, the control of the manufacturing process is troublesome and the cost is high.
The present inventors have conducted studies in order to avoid these conventional defects and have .
, 13~0.iOo perfected a method to accomplish this as follows. That is, when fine grain ice or dry clathrate water are used for a cement mixture, concrete/mortar can be easily manufactured by using a small amount of water without the above-mentioned ice storage unit. According to the present invention, fine grain ice is made by impregnating water into a water absorbent polymer, capable of keeping separate fine grains by freezing the water in the polymer structure. And, dry clathrate water is made in such a manner that water is impregnated into the water absorbent polymer.
The method for the production of fine grain ice or dry clathrate water for manufacturing of concrete/mortar in the present invention has the following characteristics.
1) Fine grain ice or dry clathrate water particles having stable particle size can be easily manufactured.
2) It is unnecessary to keep fine grain ice at low tem-perature until it is used and it can be used as is or by freezing just before mixture.
3) It is unnecessary to manufacture it at a specified place and manufacture can be easily performed at an optional place in the available time.
In the case where this concrete mixing technique is actually applied, however, it is necessary to manufacture fine grain ice and this method presents a problem. In the conventional method, fine grain ice is obtained by crushing an ice block. In the case where fine grain ice is obtained by crushing an ice block, the defects are as follows.
1 ) In the case where a large amount of fine grain ice is needed, a big plant equipped with special devices such as an ice crusher and a slicer is necessary.
2) Fine grain ice must be kept at low temperature until it is used and an ice storage unit is necessary to do so.
Therefore, the control of the manufacturing process is troublesome and the cost is high.
The present inventors have conducted studies in order to avoid these conventional defects and have .
, 13~0.iOo perfected a method to accomplish this as follows. That is, when fine grain ice or dry clathrate water are used for a cement mixture, concrete/mortar can be easily manufactured by using a small amount of water without the above-mentioned ice storage unit. According to the present invention, fine grain ice is made by impregnating water into a water absorbent polymer, capable of keeping separate fine grains by freezing the water in the polymer structure. And, dry clathrate water is made in such a manner that water is impregnated into the water absorbent polymer.
The method for the production of fine grain ice or dry clathrate water for manufacturing of concrete/mortar in the present invention has the following characteristics.
1) Fine grain ice or dry clathrate water particles having stable particle size can be easily manufactured.
2) It is unnecessary to keep fine grain ice at low tem-perature until it is used and it can be used as is or by freezing just before mixture.
3) It is unnecessary to manufacture it at a specified place and manufacture can be easily performed at an optional place in the available time.
4) The method can be easily applied to an existing ready-mixed concrete plant.
S) Water can be transported as fine particles to a place where it is impossible to supply water.
., 1340~03 The method for the production of concrete/mortar in the present invention has the following characteristics.
1) Low water cement ratio of high strength concrete/mortar can be easily manufactured.
2) Continuous production is easy to achieve by extrusion molding and roller molding. And, products can be easily encreased in length.
3) Since water absorbent polymer is mixed in with the cement, a remarkable effect is observed in the prevention of surface dew condensation and efflorescence.
In one specific aspect, the parent application provides, a method for the production of concrete/mortar, which consists essentially of:
lS a) mixing water with polymer particles capable of retaining their particulate shape when substantial quantities of water are absorbed therein, said particles being produced by a process which comprises:
i) forming an acrylic copolymer dispersing agent having an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms as main component;
ii) dissolving said acrylic copolymer of i) in a liquid aliphatic hydrocarbon, iii) partially neutralizing an acrylic acid monomer in aqueous solution with an alkali to form an , .. ....
13~ p:~ oo aqueous solution of partially neutralized acrylic acid, iv) adding the aqueous alkali solution of partially neutralized acrylic acid of iii) to a solution of acrylic copolymer of ii) and polymerizing the resultant mixture by water/oil suspension polymerization, and v) subjecting the resultant polymer of iv) to a cross-linking reaction in the presence of a cross-linking agent and in the presence or absence of a particulate inorganic compound;
b) mixing cement or cement and aggregate with said product of step a) and c) expelling the water absorbed in said polymer particles in the mixture of b) to the outside thereof by a molding method so as to cause hydration of said cement.
Preferably the molding method comprises pressing or extrusion.
Suitably the polymer particles containing water from step a) are frozen prior to step b) and melted when desired to cause hydration of the cement.
134 D .~ 00 The present invention discloses and claims in one aspect water absorbent polymer being polymerized and formed by using an acrylic copolymer as a dispersing agent, said acrylic copolymer comprising an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms as a main component, said water absorbent polymer being capable of keeping absorbed water therein in the form of independent grains and having the property of each grain slipping by each other.
In a further aspect there is provided a method for the production of a water absorbent polymer which comprises:
a) dissolving an acrylic copolymer as a dispersing agent in a liquid aliphatic hydrocarbon; b) partially neutralizing an acrylic acid monomer in an aqueous solution with an alkali to form an aqueous solution of partially neutralized acrylic acid; c) dispersing the aqueous solution of partially neutralized acrylic acid of b) in the solution of acrylic copolymer of a) to polymerize by w/o suspension polymerization; and d) subjecting the resultant polymer of c) to a crosslinking reaction in the presence of a crosslinking agent and in the presence or absence of an inorganic compound, and to drying.
In preferred embodiments of this further aspect there are provided:
- 5a -13~00 The above method wherein the acrylic copolymer is alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms as a main component.
The above method wherein the acrylic copolymer is a S copolymer in which the following are components: a) an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms, in the amount of 40 to 95 weight percent: b) a monomer selected from acrylic acid derivatives, methacrylic acid derivatives, acrylic amide derivatives, methacrylic amide derivatives having hydrophilicity and a mixture thereof, in the amount of S to 40 weight percent; and c) unsaturated monomers capable of copolymerizing said (a) and (b), in the amount of 0 to 40 weight percent.
The above method wherein the crosslinking agent is ethylene glycol diglycidyl ether.
The above method wherein the amount of the crosslinking agent is O.OS to 2 weight percent relative to the amount of the partially neutralized acrylic acid.
- Sb -.. . . .. ..
The invention will be described in more detail by reference to the accompanying drawings, in which:
Fig.l is a table which depicts the glass transition point of certain monomers; and Fig.2 is a table which depicts the result of an evaluation of the water absorbent polymers in the Examples 1 through 6 and the Comparison Examples 1 through 3.
The water absorbent polymer for use in the present invention is obtained by dissolving acrylic copolymer in an aliphatic hydrocarbon to form a solution, and dispersing acrylic acid and an alkali metal salt aqueous solution thereof in said solution. Polymerization is performed by a water/oil (W/0) type suspension polymerization method and crosslinking is then performed in the presence or absence of an inorganic compound by means of a crosslinking agent followed by drying.
An acrylic copolymer to be used as a dispersing agent when the water absorbent polymer for use in the present invention is manufactured, is a copolymer in which the following are the components.
(a) Alkyl acrylate or alkyl methacrylate monomers in which the number of carbons in the alkyl groups is 8 or more are present at 40-95 weight percent.
, . . . .
1340501~
(b) One or more kinds of monomers selected from acrylic acid derivatives, methacrylic acid derivatives, acrylic amide derivatives and methacrylic amide derivatives containing a carboxyl group, an amino group, a quarternary ammonium group or a hydroxyl group are present at 5-40 weight percent.
(c) Unsaturated monomers capable of copolymerizing with the above-mentioned (a), (b) are present at 0-40 weight percent.
Any alkyl acrylates or alkyl methacrylates are suitable for component (a) if the number of carbons of the alkyl groups is at least 8. Monomers which are commercially available are 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, tridecyl acrylate, tridecyl methacrylate, a mixture of lauryl acrylate and tridecyl acrylate, stearyl acrylate, stearyl methacrylate and the like.
In selecting component (a20 transition point is, the harder it is for beads blocking to '~/~
occur when the dispersing agent is synthesized in an Q~d type suspension polymerization. Therefore, a higher glass transition point is convenient. The glass transition point of each monomer is shown in Fig.l.~5 For instance, 2-ethylhexyl methacrylate, lauryl acry-, ,.~ 13~50i) late, a mixture of lauryl acrylate and tridecyl acrylate,tridecyl acrylate, stearyl acrylate, stearyl methacrylate and the like are available for use herein.
The acrylic acid derivatives, methacrylic acid deriva-tives, acrylic amide derivatives or methacrylic amide derivatives containing a carboxyl group, an amino group, a quarternary ammonium group or a hydroxyl group of the component (b) include acrylic acid, methacrylic acid, itaconic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, dimethylacrylamide, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, 2~ acrylamidepropyltrimethylammonium chloride, methacrylamidepropyltrimethylammonium chrolide and the like.
Monomers for use as component (c) are alkyl methacrylates in which the glass transition point is high, having affinity for aliphatic hydrocarbon solvents and the .. . . .... .. . . .. . ..
'- 1340~00 monomers in which the numbers of carbons of the alkyl group is less than 5 and vinyl acetate are examples. For instance, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate and vinyl acetate are suitable and methyl methacrylate, ethyl methacrylate and isobutyl methacrylate are preferred.
The ratio of the components (a), (b) and (c) largely influences the dispersion solubility to aliphatic hydrocarbon solvents, colloid dispersibility of polymerization and the properties of the water absorbent polymer, for instance, water absorbency, particle independence when water is absorbed, particle strength and particle size.
In general, component (a) is present at 40-95 weight percent, component (b) is present at 5-40 weight percent and component (cj is present at 0-40 weight percent as suitable values. It is preferred that component (a) is present at 45-70 weight percent, component (b) is present at 5-25 weight percent and component (c) is present at 20-40 weight percent.
In the case where component (a) is less than 40 weight percent, the dispersion solubility to solvent is lowered. In the case where component (a) is more than 95 weight percent, the colloid dispersibility becomes relatively worse when component (b) is less than 5 weight percent. In both cases, it is difficult to continue W/0 type suspension ., ~ .
~0501~
polymerization. The component (a) has a tendency such that the higher the percentage by weight, i.e. in the range between 40 and 95 weight percent, the better the dispersion solubility to solvent, particle independence of water absorbent polymer when water is absorbed and particle strength become. In the case where component (b) is less than 5 weight percent, the colloid dispersibility gets worse as described before. In the case where the component (b) is more than 40 weight percent, the dispersion solubility to solvent is lowered. In both cases, it is difficult to continue W/0 type suspension polymerization.
The component (b) has a tendency such that the higher the percentage by weight, i.e. in the range between 5 and 40 weight percent, the better the colloid dispersibility of polymerization is and the more the water absorbing rate of water absorbent polymer accelerates. on the contrary, in this case, the particle independence when water is absorbed and the particle strength are lowered and the particle size becomes fine. In the case where component (c) is more than 40 weight percent, the ratio of component (a) is relatively lowered and the dispersibility to solvent becomes worse. The higher the percentage by weight is in the range between o and 40 weight percent, the higher is the particle strength of the water absorbent polymer.
.. . . ... .. . ... . .
--- 13'105~1) An acrylic copolymer which is used as a dispersing agent in the present invention is synthesized by means of an O/W
type suspension polymerization method. If solution polymerization is used, there are a few cases where solvent remains or the function as dispersing agent is inferior due to low molecular weight of the resultant polymer.
An example of O/W type suspension polymerization method is as follows. Partially saponified polyvinyl alcohol is heated and dissolved in ion exchange purified water. After the atmosphere is replaced with N2, the solution in which an azo type or peroxide type initiator is dissolved is added dropwise and is dispersed in the monomer components (a), (b), (c) and the polymerization is finished by continuation of heating. After cooling, solid matter is filtered and washed and bead-like acrylic copolymer, that is, dispersing agent, is obtained by drying under reduced pressure.
The dispersing agent obtained by the above-described method is dispersed and dissolved in the aliphatic hydrocarbon solvent of the W/O type suspension polymerization. The dispersing agent is used in the 0.1 to 10 weight percent range with respect to acrylic acid and its alkali metallic salt monomer and the preferred range is 0.5 to 5 weight percent. When the quantity of dispersing agent 1340~00 is less than 0.1 weight percent, the colloid dispersibility of polymerization is labilized. When it is more than 10 weight percent, the fineness of the particle size becomes a negative economic factor.
Acrylic acid and its alkali metal salt aqueous solutions for use in the present invention are adjusted in such a manner that the acrylic acid monomer is partially neutralized by means of an aqueous solution such as sodium hydroxide and potassium hydroxide. It is preferred in consideration of water absorbency power and safety that the degree of neutralization is 60 to 85~. The concentration of monomer in aqueous solution is 35 to 75 weight percent and the preferred concentration is 40 to 70 weight percent.
In the present invention, there is no difficulty that unsaturated monomer capable of copolymerizing with acrylic acid and its acrylic acid alkali metal salt monomer is copolymerized with acrylic acid and its acrylic acid alkali metal salt monomer during the manufacture of the water absorbent polymer.
In the case where acrylic acid is polymerized with its alkali metal salt aqueous solution by W/0 type suspension polymerization method in the present invention, the initiator is of the self-crosslinking type in which a cross-linking agent monomer is not used. Therefore, the preferred initiator is a water soluble persulfate such as potassium persulfate and ammonium persulfate, and hydrogen peroxide.
The quantity of initiator is 0.1 to 2.0 weight percent to monomer and the preferred quantity is 0.2 to 1.0 weight percent.
The aliphatic hydrocarbon solvent for the W/0 type suspension polymerization in the present invention is an aliphatic hydrocarbon such as n-pentane, n-hexane, n-heptane and n-octane, or an alicyclic hydrocarbon such as cyclohexane, methylcyclohexane and decalin. The preferred ones are n-hexane, n-heptane and cyclohexane.
When the water absorbent polymer is manufactured for the present invention, the other important factor is that the crosslinking reaction is performed by means of the cross-linking agent in the presence or in the absence of an inorganic compound after the W/0 type suspension polymerization.
It is permissible that the cross-linking agent for use in the present invention is a compound having two or more functional groups capable of reacting with the carboxyl group - - - - - - -134 0 $0~
(or carboxylate group). Such a cross-linking agent may be a polyglycidyl ether such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether and glycerin triglycidyl ether, a haloepoxy compound such as epichlorohydrin and ~-methyl chlorohydrin, a polyaldehyde such as glutaraldehydeand glyoxal and the like. The preferred one is ethylene glycol glycidyl ether.
The amount of added cross-linking agent depends on the type of cross-linking agent and the type of dispersing agent.
The range is usually 0.05 to 2 weight percent relative to the acrylic acid and its alkali metal salt monomer. When the quantity of the above-described cross-linking agent is less than 0.05 weight percent, the particle independence when lS water is absorbed and the particle strength are unsatisfactory. When it is more than 2 weight percent, the cross-linking density is too high. Therefore, the water absorbency is too low.
With the cross-linking reaction, the particle inde-pendence, when water is absorbed, increases by the addition of an inorganic compound. The inorganic compound is, for instance, white carbon, talc, hydrotalcite, pulverized silica (commercially available under the trademark "Aerosil" made by NIPPON AEROSIL KABUSHIKI KAISHA). Further, no difficulty 340~01~
arises if a surface active agent is added. Well known nonionic surface active agents and the like are used.
The method of performing the cross-linking reaction is to add the crosslinking agent during azeotropic distillation, heating and drying under reduced pressure, as is well known, and the addition during azeotropic distillation is easy.
The water absorbent polymer for use in the present in-vention is different from commercially produced polymers and shows particle independence when water is absorbed. The more the component (a) acrylic copolymer dispersing agent employed and the more cross-linking agent employed, the greater the effects observed. It can, therefore, be presumed that slip-page of water absorbed polymer affects the above-described particle independence. The component (a) dispersing agent upgrades the water repellency of the water absorbed polymer as does upgrading the cross-linking rate of the polymer, while the cross-linking agent increases the water absorbing rate and decreases surface tacking. By these effects, the water absorbed bead-like polymer slip by each other, become porous and appear to effect particle independence and flowability, since little water as binder is present.
Fine grain ice for production of concrete/mortar in the ... .. . . . . .
13 1050~
present invention is obtained in such a manner that the above-mentioned water absorbent polymer absorbs the necessary quantity of water to freeze so as to keep independent fine grains. It is easily manufactured. Water can be absorbed up to the water absorbency of the polymer (100 to 200 times of the water absorbent polymer weight of ion exchange purified water). And, dry clathrate water for production of concrete/mortar is obtained only in such a manner that the above-mentioned water absorbent polymer absorbs the necessary quantity of water. It is desirable that the amount of water to be absorbed is less than half of the water absorbency capacity of the polymer in order to keep independent fine grains.
The particle size of the fine grain ice or dry clathrate water can be freely varied in the 0.03 to 3.0 mm range by changing the particle size of the water absorbent polymer and the amount of water to be absorbed, and can be selected in accordance with the working conditions when the cement is mixed.
Concrete/mortar is manufactured in such a manner that fine grain ice or dry clathrate water of the present inven-tion is mixed with the cement or cement and aggregate in powder condition and after is expelled to the outer portion by means of a pressure molding or extrusion molding method so .. ...
13 ~i O?~OO
as to cause hydration of the surrounding cement.
The production method of the present invention will be further explained according to the following examples.
However, the present invention is not restricted by these ex-amples.
Water absorbency, particle size and particle indepen-dence when water is absorbed were obtained by the following methods as shown below.
The value of water absorbency of ion exchange purified water was obtained in such a manner that dry polymer, 0.5 g, was dispersed in ion exchange purified water, 1 L, and the swelling polymer weight (W) was obtained by filtering, by means of an 80-mesh wire gauze after standing for twenty-four hours, was measured and this value was divided by the original dry polymer weight (Wo). That is, it was decided that the water absorbency of the ion exchange purified water (g/g) was W/Wo.
The value of water absorbency of 0.9% salt water was obtained in such a manner that dry polymer, 0.2 g, was dis-persed in 0.9% salt water, 60 g. The swelling polymer weight (W) obtained by filtering, by means of a 100-mesh wire gauze after standing for twenty minutes, was measured and this value was divided by the original dry polymer (Wo). That is, it was decided that the water absorbency of 0.9% salt water (g/g) was W/Wo.
The particle size of the water absorbent polymer (in dry condition) was measured by means of an automatic grading dis-tribution measuring apparatus CAPA-300 made by HORIBA
SEISAKUSHO KABUSHIKI KAISHA by using the decanter method. It was decided that the median on a basis of the area was the particle size.
It was decided that the particle size of the water absorbed polymer was the average obtained on the basis of photographing with an optical microscope after ion exchange purified water, 50 cc, was added to dry polymer, 1.0 g, and the polymer absorbed all of the water. The particle independence when water was absorbed was judged by the following standard.
o: Each particle is independent and has flowability.
~: Each particle is partially dependent and inferior in flowability.
x: Each particle shows gelation dependence perfectly and has no flowability.
The composition examples of the dispersing agent 1340~0~
' (acrylic copolymer) will be given hereinafter.
Composition Example 1 Ion exchange purified water, 150 g, was fed into a 500 ml separating flask equipped with an agitator, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introduction tube. Partially saponified polyvinyl alcohol (GH-23 made by NIHON GOHSEI KAGAKU KABUSHIKI KAISHA), 0.2 g, was added as a dispersing agent and the atmosphere was replaced with N2 after heating and dissolution of the materials.
Azobisdimethylvaleronitrile, 1.0 g, was added to a mixture of lauryl acrylate and tridecyl acrylate (LTA made by OHSAKA YUKI KAGAKU KABUSHIKI KAISHA) 32.5 g, hydroxy ethyl methacrylate, 10.0 g, and methyl methacrylate, 17.5 g, in a conical flask in advance to dissolve. This mixture was added to the above-mentioned separating flask and reacted for one hour under nitrogen bubbling. The reaction was maintained for 5 hours at 65~C, after which the reaction was finished.
The solid matter produced was filtered after cooling, washed and dried under reduced pressure. A bead-like dispersing agent (1) was obtained.
* Trade mark , . . . . ~ ~
i340.~01~
, . . .
Composition Example 2 A bead-like dispersing agent (2) was obtained by operating in the same way as in Example 1, except that a mixture of lauryl acrylate and tridecyl acrylate, 25.0 g, methacrylic acid, 5.0 g, dimethylaminoethyl methacrylate, 5.0 g, and methyl methacrylate, 17.5 g, was used.
Composition Example 3 A bead-like dispersing agent (3) was obtained by operating in the same way as in Example 1, except that stearyl methacrylate, 30 g, dimethylaminopropyl methacrylamide, lO.0 g, and methyl methacrylate, lO.0 g, was used.
The examples of water absorbent polymer will be given hereinafter.
Example 1 N-hexane, 360.7 g, and the dispersing agent (1), 4.32 g, were fed in to a 1 L separating flask equipped with an agitator, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introduction tube. The temperature was raised to 50~C to disperse and dissolve the materials and the atmosphere was replaced with N2.
13~0501~
Acrylic acid, 72.0 g, was partially neutralized by means of sodium hydroxide, 32.2 g, dissolved in ion exchange purified water, 103.6 g, in a conical flask in advance and potassium persulfate, 0.24 g, was dissolved therein at room S temperature. This monomer aqueous solution was added to the above-described separating flask under nitrogen bubbling at an agitation speed of 300 rpm for an hour. After reflux for two hours, 30% aqueous hydrogen peroxide, 0.1 g, was added thereto and polymerization was completed by continuing reflux for an hour. Thereafter, ethylene glycol diglycidyl ether, 0.73 g, was added thereto, azeotropic distillation was performed and drying under reduced pressure after filtration was effected and a white bead-like polymer was obtained.
There was little attachment of the polymer particles in the separating flask.
The obtained dry polymer showed a water absorbency to ion exchange purified water of 125 (g/g), the water absorb-ency to 0.9% salt water was 33 (g/g), the particle size in dry condition was 120 ~m and the particle size when water was absorbed was 480 ~m. The particle independence when water was absorbed was maintained.
Examples 2 and 3 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that the dispersing . .
13~0~00 agents (2), (3) obtained in the composition Examples 2, 3 in-stead of the dispersing agent (1) of Example 1 were used.
There was little attachment of polymer in the separating flask.
Example 4 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that cyclohexane instead of the n-hexane of the Example 1 was used. There was little attachment of polymer in the separating flask.
Examples 5-6 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that the ethylene glycol diglycidyl ether, 0.73 g, of Example 1 was added at 0.18 g and 1.46 g. There was little attachment of polymer in the separating flask.
Comparison Example 1 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that the ethylene glycol diglycidyl ether of Example 1 was not added. There was little attachment of polymer in the separating flask.
Comparison Example 2 A white powdery polymer was obtained by operating in the 13~0.50~
same way as in example 1 but by using sorbitan monolaurate instead of the dispersing agent (1) of Example 1. The attachment of polymer to the wall surface and the agitating blade in the separating flask was observed.
Comparison Example 3 A commercially available product, AQUALIC CA-W
(made by NIHON SHOKUBAI KAGAKU KOGYO KABUSHIKI KAIS~A) was evaluated in Examples l through 6 and Comparison Examples 1 through 3 and the results are shown in Fig. 2.
Examples of the production methods for fine grain ice and concrete/mortar wlll be given hereinafter.
Example A (Fine Grain Ice) Drinking water, 100 kg, was fed into a 100 L vessel equipped with an agitator and the water absorbent polymer, 1.0 kg, of Example 1 was gradually added thereto with agitation. After the water was absorbed, agitation was stopped and the fine grain polymer which absorbed the water was subjected to freezing. Then, the frozen polymer formed independent fine grain ice by a simple mechanical operation and was agitated by a mixer with sand and cement in the following proportions to form mortar:
* Trade mark ... _ _ . . .......... . ... . . .
1340~00 cement : fine grain ice : quartz sand (dry) =100 : 28 : 20 This mortar was formed into a plate which was 50 mm wide and 12 mm thick by a vacuum deaeration type extrusion molding machine. Five specimens which were 350 mm long were made by using this plate. A bending tension test was performed after curing at room temperature for 14 days. The bending tension strength (kg/cm2) were 185.3, 211.1, 237.2, 191.0 and 177.9 and the average was 200.5 kg/cm2.
Example B (Fine Grain Ice) After water was absorbed, a powder mixture was prepared in the following ratio by using frozen fine grain polymer produced by the same method as in Example A.
cement : fine grain ice : quartz sand (dry) = 100 : 24 : 20 Thereafter, a plate which was 50 mm wide and 12 mm thick was formed by means of a vacuum deaeration type extrusion molding machine. The bending tension strength (kg/cm2) of this plate which was cured for 14 days at 20~C in a room was 249.5, 220.1 and 220.3 and the average was 230.0 kg/cm2.
Example C (Fine Grain Ice) After water was absorbed, a powdery mixture was prepared 1~40500 in the following ratio by using the frozen fine grain polymer produced in the same manner as in Example A to form a plate by a means of vacuum deaeration type extrusion molding machine.
cement : fine grain ice : quartz sand (dry) = 100 : 32 : 20 The bending tension strength (kg/cm2) of this plate after curing at 20~C in a room for 14 days was 176.8, 157.0 and 146.1 and the average was 160.0 kg/cm2.
Example D (Dry Clathrate Water) Drinking water, 50 kg, was fed into a 100 L vessel equipped with an agitator, and water absorbing polymer, 1.0 kg, was gradually added thereto with agitation. After the water was absorbed, agitation was stopped to manufacture dry clathrate water. By using this dry clathrate water, agitation was performed by means of a mixer with sand and cement in the following proportions to manufacture mortar.
cement : dry clathrate water : quartz sand (dry) = 100 : 28 : 20 The bending test result of the plate manufactured and cured in the same manner as in Example A by using this mortar was 218.4, 179.5 and 180.9 and the average was 192.9 kg/cm2.
l~OSO~
Example E (Dry Clathrate Water) The same method as in Example D was performed.
The bending test result of the resultant plate from the following ratio was 241.5, 216.8 and 206.3 and the average 5 was 221.5 kg/cm2.
cement: dry clathrate water: quartz sand (dry) = 100: 24: 20 10 Example F (Dry Clathrate Water) The same method as in Example D was performed.
The bending test result of the resultant plate from the following ratio was 166.3, 147.0 and 146.1 and the average was 153.1 kg/cm2.
cement: dry clathrate water: quartz sand (dry) = 100: 32: 20.
S) Water can be transported as fine particles to a place where it is impossible to supply water.
., 1340~03 The method for the production of concrete/mortar in the present invention has the following characteristics.
1) Low water cement ratio of high strength concrete/mortar can be easily manufactured.
2) Continuous production is easy to achieve by extrusion molding and roller molding. And, products can be easily encreased in length.
3) Since water absorbent polymer is mixed in with the cement, a remarkable effect is observed in the prevention of surface dew condensation and efflorescence.
In one specific aspect, the parent application provides, a method for the production of concrete/mortar, which consists essentially of:
lS a) mixing water with polymer particles capable of retaining their particulate shape when substantial quantities of water are absorbed therein, said particles being produced by a process which comprises:
i) forming an acrylic copolymer dispersing agent having an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms as main component;
ii) dissolving said acrylic copolymer of i) in a liquid aliphatic hydrocarbon, iii) partially neutralizing an acrylic acid monomer in aqueous solution with an alkali to form an , .. ....
13~ p:~ oo aqueous solution of partially neutralized acrylic acid, iv) adding the aqueous alkali solution of partially neutralized acrylic acid of iii) to a solution of acrylic copolymer of ii) and polymerizing the resultant mixture by water/oil suspension polymerization, and v) subjecting the resultant polymer of iv) to a cross-linking reaction in the presence of a cross-linking agent and in the presence or absence of a particulate inorganic compound;
b) mixing cement or cement and aggregate with said product of step a) and c) expelling the water absorbed in said polymer particles in the mixture of b) to the outside thereof by a molding method so as to cause hydration of said cement.
Preferably the molding method comprises pressing or extrusion.
Suitably the polymer particles containing water from step a) are frozen prior to step b) and melted when desired to cause hydration of the cement.
134 D .~ 00 The present invention discloses and claims in one aspect water absorbent polymer being polymerized and formed by using an acrylic copolymer as a dispersing agent, said acrylic copolymer comprising an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms as a main component, said water absorbent polymer being capable of keeping absorbed water therein in the form of independent grains and having the property of each grain slipping by each other.
In a further aspect there is provided a method for the production of a water absorbent polymer which comprises:
a) dissolving an acrylic copolymer as a dispersing agent in a liquid aliphatic hydrocarbon; b) partially neutralizing an acrylic acid monomer in an aqueous solution with an alkali to form an aqueous solution of partially neutralized acrylic acid; c) dispersing the aqueous solution of partially neutralized acrylic acid of b) in the solution of acrylic copolymer of a) to polymerize by w/o suspension polymerization; and d) subjecting the resultant polymer of c) to a crosslinking reaction in the presence of a crosslinking agent and in the presence or absence of an inorganic compound, and to drying.
In preferred embodiments of this further aspect there are provided:
- 5a -13~00 The above method wherein the acrylic copolymer is alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms as a main component.
The above method wherein the acrylic copolymer is a S copolymer in which the following are components: a) an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms, in the amount of 40 to 95 weight percent: b) a monomer selected from acrylic acid derivatives, methacrylic acid derivatives, acrylic amide derivatives, methacrylic amide derivatives having hydrophilicity and a mixture thereof, in the amount of S to 40 weight percent; and c) unsaturated monomers capable of copolymerizing said (a) and (b), in the amount of 0 to 40 weight percent.
The above method wherein the crosslinking agent is ethylene glycol diglycidyl ether.
The above method wherein the amount of the crosslinking agent is O.OS to 2 weight percent relative to the amount of the partially neutralized acrylic acid.
- Sb -.. . . .. ..
The invention will be described in more detail by reference to the accompanying drawings, in which:
Fig.l is a table which depicts the glass transition point of certain monomers; and Fig.2 is a table which depicts the result of an evaluation of the water absorbent polymers in the Examples 1 through 6 and the Comparison Examples 1 through 3.
The water absorbent polymer for use in the present invention is obtained by dissolving acrylic copolymer in an aliphatic hydrocarbon to form a solution, and dispersing acrylic acid and an alkali metal salt aqueous solution thereof in said solution. Polymerization is performed by a water/oil (W/0) type suspension polymerization method and crosslinking is then performed in the presence or absence of an inorganic compound by means of a crosslinking agent followed by drying.
An acrylic copolymer to be used as a dispersing agent when the water absorbent polymer for use in the present invention is manufactured, is a copolymer in which the following are the components.
(a) Alkyl acrylate or alkyl methacrylate monomers in which the number of carbons in the alkyl groups is 8 or more are present at 40-95 weight percent.
, . . . .
1340501~
(b) One or more kinds of monomers selected from acrylic acid derivatives, methacrylic acid derivatives, acrylic amide derivatives and methacrylic amide derivatives containing a carboxyl group, an amino group, a quarternary ammonium group or a hydroxyl group are present at 5-40 weight percent.
(c) Unsaturated monomers capable of copolymerizing with the above-mentioned (a), (b) are present at 0-40 weight percent.
Any alkyl acrylates or alkyl methacrylates are suitable for component (a) if the number of carbons of the alkyl groups is at least 8. Monomers which are commercially available are 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, tridecyl acrylate, tridecyl methacrylate, a mixture of lauryl acrylate and tridecyl acrylate, stearyl acrylate, stearyl methacrylate and the like.
In selecting component (a20 transition point is, the harder it is for beads blocking to '~/~
occur when the dispersing agent is synthesized in an Q~d type suspension polymerization. Therefore, a higher glass transition point is convenient. The glass transition point of each monomer is shown in Fig.l.~5 For instance, 2-ethylhexyl methacrylate, lauryl acry-, ,.~ 13~50i) late, a mixture of lauryl acrylate and tridecyl acrylate,tridecyl acrylate, stearyl acrylate, stearyl methacrylate and the like are available for use herein.
The acrylic acid derivatives, methacrylic acid deriva-tives, acrylic amide derivatives or methacrylic amide derivatives containing a carboxyl group, an amino group, a quarternary ammonium group or a hydroxyl group of the component (b) include acrylic acid, methacrylic acid, itaconic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, dimethylacrylamide, dimethylaminopropylacrylamide, dimethylaminopropylmethacrylamide, 2~ acrylamidepropyltrimethylammonium chloride, methacrylamidepropyltrimethylammonium chrolide and the like.
Monomers for use as component (c) are alkyl methacrylates in which the glass transition point is high, having affinity for aliphatic hydrocarbon solvents and the .. . . .... .. . . .. . ..
'- 1340~00 monomers in which the numbers of carbons of the alkyl group is less than 5 and vinyl acetate are examples. For instance, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate and vinyl acetate are suitable and methyl methacrylate, ethyl methacrylate and isobutyl methacrylate are preferred.
The ratio of the components (a), (b) and (c) largely influences the dispersion solubility to aliphatic hydrocarbon solvents, colloid dispersibility of polymerization and the properties of the water absorbent polymer, for instance, water absorbency, particle independence when water is absorbed, particle strength and particle size.
In general, component (a) is present at 40-95 weight percent, component (b) is present at 5-40 weight percent and component (cj is present at 0-40 weight percent as suitable values. It is preferred that component (a) is present at 45-70 weight percent, component (b) is present at 5-25 weight percent and component (c) is present at 20-40 weight percent.
In the case where component (a) is less than 40 weight percent, the dispersion solubility to solvent is lowered. In the case where component (a) is more than 95 weight percent, the colloid dispersibility becomes relatively worse when component (b) is less than 5 weight percent. In both cases, it is difficult to continue W/0 type suspension ., ~ .
~0501~
polymerization. The component (a) has a tendency such that the higher the percentage by weight, i.e. in the range between 40 and 95 weight percent, the better the dispersion solubility to solvent, particle independence of water absorbent polymer when water is absorbed and particle strength become. In the case where component (b) is less than 5 weight percent, the colloid dispersibility gets worse as described before. In the case where the component (b) is more than 40 weight percent, the dispersion solubility to solvent is lowered. In both cases, it is difficult to continue W/0 type suspension polymerization.
The component (b) has a tendency such that the higher the percentage by weight, i.e. in the range between 5 and 40 weight percent, the better the colloid dispersibility of polymerization is and the more the water absorbing rate of water absorbent polymer accelerates. on the contrary, in this case, the particle independence when water is absorbed and the particle strength are lowered and the particle size becomes fine. In the case where component (c) is more than 40 weight percent, the ratio of component (a) is relatively lowered and the dispersibility to solvent becomes worse. The higher the percentage by weight is in the range between o and 40 weight percent, the higher is the particle strength of the water absorbent polymer.
.. . . ... .. . ... . .
--- 13'105~1) An acrylic copolymer which is used as a dispersing agent in the present invention is synthesized by means of an O/W
type suspension polymerization method. If solution polymerization is used, there are a few cases where solvent remains or the function as dispersing agent is inferior due to low molecular weight of the resultant polymer.
An example of O/W type suspension polymerization method is as follows. Partially saponified polyvinyl alcohol is heated and dissolved in ion exchange purified water. After the atmosphere is replaced with N2, the solution in which an azo type or peroxide type initiator is dissolved is added dropwise and is dispersed in the monomer components (a), (b), (c) and the polymerization is finished by continuation of heating. After cooling, solid matter is filtered and washed and bead-like acrylic copolymer, that is, dispersing agent, is obtained by drying under reduced pressure.
The dispersing agent obtained by the above-described method is dispersed and dissolved in the aliphatic hydrocarbon solvent of the W/O type suspension polymerization. The dispersing agent is used in the 0.1 to 10 weight percent range with respect to acrylic acid and its alkali metallic salt monomer and the preferred range is 0.5 to 5 weight percent. When the quantity of dispersing agent 1340~00 is less than 0.1 weight percent, the colloid dispersibility of polymerization is labilized. When it is more than 10 weight percent, the fineness of the particle size becomes a negative economic factor.
Acrylic acid and its alkali metal salt aqueous solutions for use in the present invention are adjusted in such a manner that the acrylic acid monomer is partially neutralized by means of an aqueous solution such as sodium hydroxide and potassium hydroxide. It is preferred in consideration of water absorbency power and safety that the degree of neutralization is 60 to 85~. The concentration of monomer in aqueous solution is 35 to 75 weight percent and the preferred concentration is 40 to 70 weight percent.
In the present invention, there is no difficulty that unsaturated monomer capable of copolymerizing with acrylic acid and its acrylic acid alkali metal salt monomer is copolymerized with acrylic acid and its acrylic acid alkali metal salt monomer during the manufacture of the water absorbent polymer.
In the case where acrylic acid is polymerized with its alkali metal salt aqueous solution by W/0 type suspension polymerization method in the present invention, the initiator is of the self-crosslinking type in which a cross-linking agent monomer is not used. Therefore, the preferred initiator is a water soluble persulfate such as potassium persulfate and ammonium persulfate, and hydrogen peroxide.
The quantity of initiator is 0.1 to 2.0 weight percent to monomer and the preferred quantity is 0.2 to 1.0 weight percent.
The aliphatic hydrocarbon solvent for the W/0 type suspension polymerization in the present invention is an aliphatic hydrocarbon such as n-pentane, n-hexane, n-heptane and n-octane, or an alicyclic hydrocarbon such as cyclohexane, methylcyclohexane and decalin. The preferred ones are n-hexane, n-heptane and cyclohexane.
When the water absorbent polymer is manufactured for the present invention, the other important factor is that the crosslinking reaction is performed by means of the cross-linking agent in the presence or in the absence of an inorganic compound after the W/0 type suspension polymerization.
It is permissible that the cross-linking agent for use in the present invention is a compound having two or more functional groups capable of reacting with the carboxyl group - - - - - - -134 0 $0~
(or carboxylate group). Such a cross-linking agent may be a polyglycidyl ether such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether and glycerin triglycidyl ether, a haloepoxy compound such as epichlorohydrin and ~-methyl chlorohydrin, a polyaldehyde such as glutaraldehydeand glyoxal and the like. The preferred one is ethylene glycol glycidyl ether.
The amount of added cross-linking agent depends on the type of cross-linking agent and the type of dispersing agent.
The range is usually 0.05 to 2 weight percent relative to the acrylic acid and its alkali metal salt monomer. When the quantity of the above-described cross-linking agent is less than 0.05 weight percent, the particle independence when lS water is absorbed and the particle strength are unsatisfactory. When it is more than 2 weight percent, the cross-linking density is too high. Therefore, the water absorbency is too low.
With the cross-linking reaction, the particle inde-pendence, when water is absorbed, increases by the addition of an inorganic compound. The inorganic compound is, for instance, white carbon, talc, hydrotalcite, pulverized silica (commercially available under the trademark "Aerosil" made by NIPPON AEROSIL KABUSHIKI KAISHA). Further, no difficulty 340~01~
arises if a surface active agent is added. Well known nonionic surface active agents and the like are used.
The method of performing the cross-linking reaction is to add the crosslinking agent during azeotropic distillation, heating and drying under reduced pressure, as is well known, and the addition during azeotropic distillation is easy.
The water absorbent polymer for use in the present in-vention is different from commercially produced polymers and shows particle independence when water is absorbed. The more the component (a) acrylic copolymer dispersing agent employed and the more cross-linking agent employed, the greater the effects observed. It can, therefore, be presumed that slip-page of water absorbed polymer affects the above-described particle independence. The component (a) dispersing agent upgrades the water repellency of the water absorbed polymer as does upgrading the cross-linking rate of the polymer, while the cross-linking agent increases the water absorbing rate and decreases surface tacking. By these effects, the water absorbed bead-like polymer slip by each other, become porous and appear to effect particle independence and flowability, since little water as binder is present.
Fine grain ice for production of concrete/mortar in the ... .. . . . . .
13 1050~
present invention is obtained in such a manner that the above-mentioned water absorbent polymer absorbs the necessary quantity of water to freeze so as to keep independent fine grains. It is easily manufactured. Water can be absorbed up to the water absorbency of the polymer (100 to 200 times of the water absorbent polymer weight of ion exchange purified water). And, dry clathrate water for production of concrete/mortar is obtained only in such a manner that the above-mentioned water absorbent polymer absorbs the necessary quantity of water. It is desirable that the amount of water to be absorbed is less than half of the water absorbency capacity of the polymer in order to keep independent fine grains.
The particle size of the fine grain ice or dry clathrate water can be freely varied in the 0.03 to 3.0 mm range by changing the particle size of the water absorbent polymer and the amount of water to be absorbed, and can be selected in accordance with the working conditions when the cement is mixed.
Concrete/mortar is manufactured in such a manner that fine grain ice or dry clathrate water of the present inven-tion is mixed with the cement or cement and aggregate in powder condition and after is expelled to the outer portion by means of a pressure molding or extrusion molding method so .. ...
13 ~i O?~OO
as to cause hydration of the surrounding cement.
The production method of the present invention will be further explained according to the following examples.
However, the present invention is not restricted by these ex-amples.
Water absorbency, particle size and particle indepen-dence when water is absorbed were obtained by the following methods as shown below.
The value of water absorbency of ion exchange purified water was obtained in such a manner that dry polymer, 0.5 g, was dispersed in ion exchange purified water, 1 L, and the swelling polymer weight (W) was obtained by filtering, by means of an 80-mesh wire gauze after standing for twenty-four hours, was measured and this value was divided by the original dry polymer weight (Wo). That is, it was decided that the water absorbency of the ion exchange purified water (g/g) was W/Wo.
The value of water absorbency of 0.9% salt water was obtained in such a manner that dry polymer, 0.2 g, was dis-persed in 0.9% salt water, 60 g. The swelling polymer weight (W) obtained by filtering, by means of a 100-mesh wire gauze after standing for twenty minutes, was measured and this value was divided by the original dry polymer (Wo). That is, it was decided that the water absorbency of 0.9% salt water (g/g) was W/Wo.
The particle size of the water absorbent polymer (in dry condition) was measured by means of an automatic grading dis-tribution measuring apparatus CAPA-300 made by HORIBA
SEISAKUSHO KABUSHIKI KAISHA by using the decanter method. It was decided that the median on a basis of the area was the particle size.
It was decided that the particle size of the water absorbed polymer was the average obtained on the basis of photographing with an optical microscope after ion exchange purified water, 50 cc, was added to dry polymer, 1.0 g, and the polymer absorbed all of the water. The particle independence when water was absorbed was judged by the following standard.
o: Each particle is independent and has flowability.
~: Each particle is partially dependent and inferior in flowability.
x: Each particle shows gelation dependence perfectly and has no flowability.
The composition examples of the dispersing agent 1340~0~
' (acrylic copolymer) will be given hereinafter.
Composition Example 1 Ion exchange purified water, 150 g, was fed into a 500 ml separating flask equipped with an agitator, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introduction tube. Partially saponified polyvinyl alcohol (GH-23 made by NIHON GOHSEI KAGAKU KABUSHIKI KAISHA), 0.2 g, was added as a dispersing agent and the atmosphere was replaced with N2 after heating and dissolution of the materials.
Azobisdimethylvaleronitrile, 1.0 g, was added to a mixture of lauryl acrylate and tridecyl acrylate (LTA made by OHSAKA YUKI KAGAKU KABUSHIKI KAISHA) 32.5 g, hydroxy ethyl methacrylate, 10.0 g, and methyl methacrylate, 17.5 g, in a conical flask in advance to dissolve. This mixture was added to the above-mentioned separating flask and reacted for one hour under nitrogen bubbling. The reaction was maintained for 5 hours at 65~C, after which the reaction was finished.
The solid matter produced was filtered after cooling, washed and dried under reduced pressure. A bead-like dispersing agent (1) was obtained.
* Trade mark , . . . . ~ ~
i340.~01~
, . . .
Composition Example 2 A bead-like dispersing agent (2) was obtained by operating in the same way as in Example 1, except that a mixture of lauryl acrylate and tridecyl acrylate, 25.0 g, methacrylic acid, 5.0 g, dimethylaminoethyl methacrylate, 5.0 g, and methyl methacrylate, 17.5 g, was used.
Composition Example 3 A bead-like dispersing agent (3) was obtained by operating in the same way as in Example 1, except that stearyl methacrylate, 30 g, dimethylaminopropyl methacrylamide, lO.0 g, and methyl methacrylate, lO.0 g, was used.
The examples of water absorbent polymer will be given hereinafter.
Example 1 N-hexane, 360.7 g, and the dispersing agent (1), 4.32 g, were fed in to a 1 L separating flask equipped with an agitator, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introduction tube. The temperature was raised to 50~C to disperse and dissolve the materials and the atmosphere was replaced with N2.
13~0501~
Acrylic acid, 72.0 g, was partially neutralized by means of sodium hydroxide, 32.2 g, dissolved in ion exchange purified water, 103.6 g, in a conical flask in advance and potassium persulfate, 0.24 g, was dissolved therein at room S temperature. This monomer aqueous solution was added to the above-described separating flask under nitrogen bubbling at an agitation speed of 300 rpm for an hour. After reflux for two hours, 30% aqueous hydrogen peroxide, 0.1 g, was added thereto and polymerization was completed by continuing reflux for an hour. Thereafter, ethylene glycol diglycidyl ether, 0.73 g, was added thereto, azeotropic distillation was performed and drying under reduced pressure after filtration was effected and a white bead-like polymer was obtained.
There was little attachment of the polymer particles in the separating flask.
The obtained dry polymer showed a water absorbency to ion exchange purified water of 125 (g/g), the water absorb-ency to 0.9% salt water was 33 (g/g), the particle size in dry condition was 120 ~m and the particle size when water was absorbed was 480 ~m. The particle independence when water was absorbed was maintained.
Examples 2 and 3 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that the dispersing . .
13~0~00 agents (2), (3) obtained in the composition Examples 2, 3 in-stead of the dispersing agent (1) of Example 1 were used.
There was little attachment of polymer in the separating flask.
Example 4 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that cyclohexane instead of the n-hexane of the Example 1 was used. There was little attachment of polymer in the separating flask.
Examples 5-6 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that the ethylene glycol diglycidyl ether, 0.73 g, of Example 1 was added at 0.18 g and 1.46 g. There was little attachment of polymer in the separating flask.
Comparison Example 1 A white bead-like polymer was obtained by operating in the same way as in Example 1 except that the ethylene glycol diglycidyl ether of Example 1 was not added. There was little attachment of polymer in the separating flask.
Comparison Example 2 A white powdery polymer was obtained by operating in the 13~0.50~
same way as in example 1 but by using sorbitan monolaurate instead of the dispersing agent (1) of Example 1. The attachment of polymer to the wall surface and the agitating blade in the separating flask was observed.
Comparison Example 3 A commercially available product, AQUALIC CA-W
(made by NIHON SHOKUBAI KAGAKU KOGYO KABUSHIKI KAIS~A) was evaluated in Examples l through 6 and Comparison Examples 1 through 3 and the results are shown in Fig. 2.
Examples of the production methods for fine grain ice and concrete/mortar wlll be given hereinafter.
Example A (Fine Grain Ice) Drinking water, 100 kg, was fed into a 100 L vessel equipped with an agitator and the water absorbent polymer, 1.0 kg, of Example 1 was gradually added thereto with agitation. After the water was absorbed, agitation was stopped and the fine grain polymer which absorbed the water was subjected to freezing. Then, the frozen polymer formed independent fine grain ice by a simple mechanical operation and was agitated by a mixer with sand and cement in the following proportions to form mortar:
* Trade mark ... _ _ . . .......... . ... . . .
1340~00 cement : fine grain ice : quartz sand (dry) =100 : 28 : 20 This mortar was formed into a plate which was 50 mm wide and 12 mm thick by a vacuum deaeration type extrusion molding machine. Five specimens which were 350 mm long were made by using this plate. A bending tension test was performed after curing at room temperature for 14 days. The bending tension strength (kg/cm2) were 185.3, 211.1, 237.2, 191.0 and 177.9 and the average was 200.5 kg/cm2.
Example B (Fine Grain Ice) After water was absorbed, a powder mixture was prepared in the following ratio by using frozen fine grain polymer produced by the same method as in Example A.
cement : fine grain ice : quartz sand (dry) = 100 : 24 : 20 Thereafter, a plate which was 50 mm wide and 12 mm thick was formed by means of a vacuum deaeration type extrusion molding machine. The bending tension strength (kg/cm2) of this plate which was cured for 14 days at 20~C in a room was 249.5, 220.1 and 220.3 and the average was 230.0 kg/cm2.
Example C (Fine Grain Ice) After water was absorbed, a powdery mixture was prepared 1~40500 in the following ratio by using the frozen fine grain polymer produced in the same manner as in Example A to form a plate by a means of vacuum deaeration type extrusion molding machine.
cement : fine grain ice : quartz sand (dry) = 100 : 32 : 20 The bending tension strength (kg/cm2) of this plate after curing at 20~C in a room for 14 days was 176.8, 157.0 and 146.1 and the average was 160.0 kg/cm2.
Example D (Dry Clathrate Water) Drinking water, 50 kg, was fed into a 100 L vessel equipped with an agitator, and water absorbing polymer, 1.0 kg, was gradually added thereto with agitation. After the water was absorbed, agitation was stopped to manufacture dry clathrate water. By using this dry clathrate water, agitation was performed by means of a mixer with sand and cement in the following proportions to manufacture mortar.
cement : dry clathrate water : quartz sand (dry) = 100 : 28 : 20 The bending test result of the plate manufactured and cured in the same manner as in Example A by using this mortar was 218.4, 179.5 and 180.9 and the average was 192.9 kg/cm2.
l~OSO~
Example E (Dry Clathrate Water) The same method as in Example D was performed.
The bending test result of the resultant plate from the following ratio was 241.5, 216.8 and 206.3 and the average 5 was 221.5 kg/cm2.
cement: dry clathrate water: quartz sand (dry) = 100: 24: 20 10 Example F (Dry Clathrate Water) The same method as in Example D was performed.
The bending test result of the resultant plate from the following ratio was 166.3, 147.0 and 146.1 and the average was 153.1 kg/cm2.
cement: dry clathrate water: quartz sand (dry) = 100: 32: 20.
Claims (14)
1. A water-absorbent polymer in particulate form capable of absorbing water by clathration, characterised in that the water-absorbent polymer is an acrylic polymer based on partially-neutralised acrylic acid, incorporating a polymeric dispersing agent comprising an acrylic copolymer linked to the water-absorbent polymer by a cross-linking reaction in the preparation of said polymer using an amount of cross-linking agent which is from 0.05 to 2 weight percent relative to the amount of the partially-neutralized acrylic acid, that the acrylic copolymer has an alkyl acrylate or methacrylate monomer having an alkyl group of eight carbon atoms or more as a main component, and that the surfaces of the polymer particles are modified so that the polymer particles retain their independent particulate form and are able to move past each other even after absorption of water by the polymeric dispersing agent.
2. A particulate water-absorbent polymer according to claim 1, wherein the acrylic polymer is obtained by water-in-oil suspension polymerisation in the presence of the acrylic copolymer polymeric dispersing agent.
3. Particles of a water-absorbent polymer according to claim 1 or 2, containing absorbed water in an amount less than half their water absorbency but retaining their particulate form and able to move past one another without sticking.
4. Particles as claimed in claim 3, having a particle size from 0.03 to 3.0 mm.
5. A method for the production of a water-absorbent particulate polymer capable of absorbing water by clathration, which method comprises:
(1) dissolving an acrylic copolymer as dispersing agent in a liquid aliphatic hydrocarbon, said acrylic copolymer being formed from the following components:
(a) an alkyl acrylate or methacrylate monomer having an alkyl group of eight carbon atoms or more, in an amount of 40 to 95 weight percent, (b) one or more hydrophilic monomers selected from acrylic acid and derivatives, methacrylic acid and derivatives, acrylamide and derivatives and methacrylamide and derivatives, all containing a carboxyl, amino, quaternary ammonium or hydroxyl group, in an amount of 5 to 40 weight percent, and (c) unsaturated monomer copolymerisable with the components (a) and (b) in an amount of 0 to 40 weight percent;
(2) partially neutralizing an acrylic acid monomer in aqueous solution with an alkali to form an aqueous solution of partially-neutralized acrylic acid;
(3) dispersing the aqueous solution of partially-neutralized acrylic acid obtained in (2) in the solution of acrylic copolymer obtained in (1), and polymerizing the acrylic acid by water-in-oil suspension polymerization;
(4) subjecting the particulate polymer obtained in (3) to a cross-linking reaction with a cross-linking agent in the presence or absence of an inorganic compound; and (5) drying the polymer particles, whereby the polymer particles retain their independent particulate form and are able to move past each other even after absorption of water.
(1) dissolving an acrylic copolymer as dispersing agent in a liquid aliphatic hydrocarbon, said acrylic copolymer being formed from the following components:
(a) an alkyl acrylate or methacrylate monomer having an alkyl group of eight carbon atoms or more, in an amount of 40 to 95 weight percent, (b) one or more hydrophilic monomers selected from acrylic acid and derivatives, methacrylic acid and derivatives, acrylamide and derivatives and methacrylamide and derivatives, all containing a carboxyl, amino, quaternary ammonium or hydroxyl group, in an amount of 5 to 40 weight percent, and (c) unsaturated monomer copolymerisable with the components (a) and (b) in an amount of 0 to 40 weight percent;
(2) partially neutralizing an acrylic acid monomer in aqueous solution with an alkali to form an aqueous solution of partially-neutralized acrylic acid;
(3) dispersing the aqueous solution of partially-neutralized acrylic acid obtained in (2) in the solution of acrylic copolymer obtained in (1), and polymerizing the acrylic acid by water-in-oil suspension polymerization;
(4) subjecting the particulate polymer obtained in (3) to a cross-linking reaction with a cross-linking agent in the presence or absence of an inorganic compound; and (5) drying the polymer particles, whereby the polymer particles retain their independent particulate form and are able to move past each other even after absorption of water.
6. A method for the production of water-absorbent polymer beads which retain a bead-like shape after absorption of water, which method comprises:
(1) dissolving a copolymer as a dispersing agent in an aliphatic hydrocarbon to form a solution, the copolymer comprising the following:
(a) an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms, in the amount of 45 to 70 weight percent, (b) one or more kinds of monomers selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, acryloyloxyethyltrimethylammonium chloride, methacryoyloxyethyltrimethylammonium chloride, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, dimethylacrylamide, dimethylaminopropyl-acrylamide, dimethylaminopropylmethacrylamide, acrylamidepropyltrimethylammonium chloride, and methacrylamidepropyltrimethylammonium chloride, in the amount of 5 to 25 weight percent, and (c) unsaturated monomers having affinity with an aliphatic hydrocarbon solvent selected from the group consisting of alkyl methacrylates wherein the alkyl group contains less than 5 carbon atoms and vinyl acetate, being capable of copolymerizing with the above-mentioned (a) and (b) so as to raise the glass transition temperature of said copolymer, in the amount of 20 to 40 weight percent;
(2) dispersing a solution of an acrylic acid and an alkali metal salt of an acrylic acid obtained by partially neutralizing an acrylic acid, in said solution of said copolymer in said aliphatic hydrocarbon, and then polymerizing the resultant mixture by water/oil suspension polymerization so as to subject said resultant mixture to a self-crosslinking reaction;
(3) subjecting said resultant polymer of (2) to a crosslinking reaction in the presence or absence of an inorganic compound by means of crosslinking agent; and (4) drying to form beads.
(1) dissolving a copolymer as a dispersing agent in an aliphatic hydrocarbon to form a solution, the copolymer comprising the following:
(a) an alkyl acrylate or methacrylate monomer having an alkyl group of eight or more carbon atoms, in the amount of 45 to 70 weight percent, (b) one or more kinds of monomers selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, acryloyloxyethyltrimethylammonium chloride, methacryoyloxyethyltrimethylammonium chloride, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, dimethylacrylamide, dimethylaminopropyl-acrylamide, dimethylaminopropylmethacrylamide, acrylamidepropyltrimethylammonium chloride, and methacrylamidepropyltrimethylammonium chloride, in the amount of 5 to 25 weight percent, and (c) unsaturated monomers having affinity with an aliphatic hydrocarbon solvent selected from the group consisting of alkyl methacrylates wherein the alkyl group contains less than 5 carbon atoms and vinyl acetate, being capable of copolymerizing with the above-mentioned (a) and (b) so as to raise the glass transition temperature of said copolymer, in the amount of 20 to 40 weight percent;
(2) dispersing a solution of an acrylic acid and an alkali metal salt of an acrylic acid obtained by partially neutralizing an acrylic acid, in said solution of said copolymer in said aliphatic hydrocarbon, and then polymerizing the resultant mixture by water/oil suspension polymerization so as to subject said resultant mixture to a self-crosslinking reaction;
(3) subjecting said resultant polymer of (2) to a crosslinking reaction in the presence or absence of an inorganic compound by means of crosslinking agent; and (4) drying to form beads.
7. A method for the production of a water-absorbent polymer according to claim 5 or 6, wherein the cross-linking agent is ethylene glycol diglycidyl ether.
8. A method for the production of a water-absorbent polymer according to claim 5, 6 or 7, wherein the amount of cross-linking agent is from 0.05 to 2 weight percent, relative to the amount of the partially-neutralized acrylic acid.
9. A method according to any one of claims 5 to 8, in which the acrylic copolymer is formed from 45 to 70 weight percent of (a), 5 to 25 weight percent of (b) and 20 to 40 weight percent of (c).
10. A method according to any one of claims 5 to 9, in which the polymerisation of the partially-neutralized acrylic acid is initiated by a self-cross-linking initiator used in an amount of 0.1 to 2.0 weight percent, based on the partially-neutralized acrylic acid.
11. A method according to any one of claims 5 to 10, in which the cross-linking is carried out in the presence of an inorganic compound selected from white carbon, talc, hydrotalcite and pulverised silica.
12. A particulate water-absorbent polymer produced by the method according to any one of claims 5 to 11.
13. Particles of a water-absorbent polymer according to claim 12, containing absorbed water in an amount less than half their water absorbency but retaining their particulate form and able to move past one another without sticking.
14. Particles as claimed in claim 13, having a particle size from 0.03 to 3.0 mm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP94308/1988 | 1988-04-16 | ||
| CA000596790A CA1335854C (en) | 1988-04-16 | 1989-04-14 | Production method of fine grain ice and dry clathrate water for manufacturing of concrete/mortar, a production method of concrete/mortar by using fine grain ice or dry clathrate water and concrete/mortar products manufactured by the production method of concrete/mortar |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000489968A Division CA1271745A (en) | 1984-09-05 | 1985-09-04 | Process for the single-stage preparation of glycosyl fluorides |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1340500C true CA1340500C (en) | 1999-04-13 |
Family
ID=4139916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616396A Expired - Fee Related CA1340500C (en) | 1988-04-16 | 1992-06-02 | Water absorbent polymer and method of production thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1340500C (en) |
-
1992
- 1992-06-02 CA CA000616396A patent/CA1340500C/en not_active Expired - Fee Related
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