Low water content plastic composition comprising hydraulic cement and method for manufacturing same

Abstract

The present invention relates to a low water content plastic composition comprising hydraulic cement and a method for manufacturing the same. The present invention provides a low water content plastic composition comprising hydraulic cement and a method for manufacturing the same, the composition being characterized by losing flowability and having plasticity since from a flowable, uniform mixture state of hydraulic cement and water with polyol and isocyanate compounds which are raw materials for forming foamed polyurethane, part of the water used in the mixture is separated and removed due to foaming in the course of formation of the foamed polyurethane.

Claims

1. A method for manufacturing a plastic composition with a low water content comprising hydraulic cement comprising: mixing hydraulic cement, water, and polyol and isocyanate compound, as ingredients for forming foamable polyurethane to obtain a flowable homogeneous mixture; polymerizing the flowable homogeneous mixture to discharge free water present between cement particles based on foaming force and thereby phase-separate liquid water from a plastic composition containing the foamable polyurethane and hydraulic cement and losing flowability; and removing the phase-separated water to obtain the plastic composition, wherein water and polyol are mixed with the hydraulic cement before the isocyanate compound is mixed with the hydraulic cement.

2. The method for manufacturing a plastic composition with a low water content comprising hydraulic cement according to claim 1, wherein the hydraulic cement comprises any one selected from Portland cement, blast furnace slag cement, pozzolan cement, expansive cement, quick-setting/rapid-hardening cement, oil-well cement, white cement, colored cement and calcium aluminate cement, or a mixture thereof, or a mixture of any one selected from these cements and plaster.

3. The method for manufacturing a plastic composition with a low water content comprising hydraulic cement according to claim 1, wherein the homogeneous mixture comprises 2.5 parts by weight to 150 parts by weight of water and 10 parts by weight to 100 parts by weight of the ingredients for forming foamable polyurethane, with respect to 100 parts by weight of the hydraulic cement.

Description

DESCRIPTION OF DRAWINGS

(1) The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is an image sequentially showing adding polymeric MDI and then stirring in Example 1 of the present invention;

(3) FIG. 2 is an image showing a state seen from above the beaker after slow stirring for 60 seconds in Example 1 of the present invention;

(4) FIG. 3 is an image showing a dense surface morphology of a cured substance obtained by molding the composition obtained in Example 1 of the present invention in the form of a film using a roller and then curing;

(5) FIG. 4 is an image showing a surface morphology of a cured substance obtained by molding the composition obtained in Example 2 of the present invention in the form of a film using a roller and then curing;

(6) FIG. 5 is an image showing a surface morphology of a cured substance obtained by molding the composition obtained in Example 3 of the present invention in the form of a film using a roller and then curing; and

(7) FIG. 6 is an image showing a surface morphology of a composite molded article using wood fibers obtained in Example 40 of the present invention.

BEST MODE

(8) The plastic composition with a low water content prepared using polyurethane and cement is obtained by mixing hydraulic cement based on Portland cement, water and, liquid polyol and an isocyanate compound for forming foamable polyurethane to obtain a flowable homogeneous mixture, stirring the mixture for a certain time and separating discharged free water therefrom.

(9) More specifically, the present invention utilizes a flowable cement paste prepared by homogenously mixing four ingredients, that is, hydraulic cement, water, the liquid isocyanate compound and polyol for forming foamable urethane so that conditions to allow cement particles to be uniformly hydrated are provided (1),

(10) wet cement particles are trapped in polyurethane during formation and foaming of polyurethane (2), and

(11) free water present between cement particles is selectively separated while discharging carbon dioxide produced by reaction of the isocyanates with water (3).

(12) As a result, provided is a cured substance that exhibits excellent adhesive strength of polyurethane, which is uniformly mixed with the cement paste and present, throughout the mixture cement paste until polyurethane is completely polymerized and cured, that exhibits plasticity enabling deformation into a desired shape until the mixed cement is hydrated and set, and that exhibits high hardness caused by cured cement with ideal uniformity and high abrasion resistance and excellent rigidity caused by dense structural properties between hydrated cement and urethane, when the mixed cement has been completely hydrated and cured.

(13) Liquid polyester, polyether or castor oil that includes two or more hydroxyl groups (OH) in a molecular structure thereof may be used as the polyol for forming foamable polyurethane used in the present invention, halogenated polyol may be useful so as to reinforce flame retardancy, and an amine-based catalyst may be mixed in an amount of 0.5 wt % to 5 wt % with respect to the weight of polyol to improve a reaction rate with the isocyanate compound.

(14) In addition, an isocyanate compound having two or more isocyanate groups (NCO) in a molecular structure may be useful as the isocyanate compound used in the present invention and the isocyanate compound is preferably less toxic and less volatile liquid polymeric MDI.

(15) The hydraulic cement used in the present invention may be arbitrarily selected from Portland cement; blast furnace slag cement, pozzolan cement and expansive cement based on Portland cement; quick-setting/rapid-hardening cement containing Portland cement and calcium aluminate cement; oil-well cement, white cement, colored cement containing a pigment, cold weather concrete and calcium aluminate cement. In order to selectively separate free water present in cement particles and obtain a uniform cured substance, first, granular hydraulic cement should be uniformly mixed with water and polyol. For this purpose, water may be added alone to the hydraulic cement and polyol may then be further added, or a combination of polyol and water may be added and then mixed, or polyol may be first added and water may then be added. In order to prevent production of un-hydrated cement particles, after addition of water to hydraulic cement, stirring for at least 30 seconds is needed.

(16) Meanwhile, water may be added in an amount of 2.5 parts by weight to 150 parts by weight with respect to 100 parts by weight of the hydraulic cement. When the amount of added water is excessively low, workability associated with stirring, transfer and the like may be deteriorated due to high viscosity of the mixture, and when the amount of added water is excessively high, cement particles may be lost in the process of aggregating the mixture and aggregation of polyurethane may be deteriorated. Thus, water is preferably added in an amount of 5 parts by weight to 65 parts by weight with respect to 100 parts by weight of the hydraulic cement.

(17) According to the present invention, an isocyanate compound is added to a homogenous mixture of hydraulic cement, water and polyol. The isocyanate compound and previously mixed polyol are the ingredients for forming foamable urethane, which form urethane bonds in the mixture and grow into macromolecules to trap hydraulic cement particles and exhibit adhesive strength. In addition, after the hydraulic cement is cured, polyurethane improve abrasion resistance and rigidity of the cured cement. Thus polyol and the isocyanate compound may be added in an amount of 10 parts by weight to 100 parts by weight, with respect to 100 parts by weight of the hydraulic cement. In this case, when the amount of added ingredients for forming urethane is excessively low, trap of cement particles is not smooth due to low aggregation and when the amount of added ingredients for forming urethane is excessively high, as compared to the amount of added cement, free water present therein is not smoothly discharged due to improved flexibility and air-tightness of the mixture.

(18) Meanwhile, the added isocyanate compound should function to produce carbon dioxide by reaction with water, in addition to reaction of polyol. Accordingly, according to the present invention, it is important to control a weight ratio between polyol and isocyanate within the range of 2:7 to 7:5.

(19) After the isocyanate compound is uniformly mixed, stirring is conducted until an appropriate amount of water is separated from the mixture while reducing a speed of a stirring impeller so that the produced urethane and hydraulic cement aggregate into one lump in a stirring container and phase-separated water is then removed. As a result, the plastic composition with a low water content prepared using foamable polyurethane and hydraulic cement according to the present invention is obtained. The amount of water separated and removed from the mixture may be changed depending on the amount of added water or mix ratio of other ingredients and is about 5 to 85% with respect to added water.

(20) The obtained plastic composition is highly adhesive and flexible, but loses adhesiveness and is thus durable enough to handle and is hard enough to undergo bending and cutting processes upon primary curing of urethane after standing at room temperature for 30 to 60 minutes and is converted into a cured substance with excellent hardness and strength due to hydration of hydraulic cement particles after standing for 4 hours or more.

(21) Hereinafter, the present invention will be described in more detail with reference to examples. The following examples are provided to describe some parts of the present invention in more detail and should be not contused as limiting the scope of the present invention.

EXAMPLE

Examples 1-5. Selection of Hydraulic Cement

(22) Portland cement, plaster, white cement, blast furnace slag cement and quick-setting cement were added in amounts of 40 g to five 200 mL beakers as shown in the following Table 1, 16 g of water was added thereto, the ingredients were stirred for 30 seconds, 8 g of polyether polyol was further added, the resulting ingredients were stirred for 30 seconds, 8 g of liquid polymeric MDI was added, rapid stirring was conducted for 10 seconds and then slow stirring was conducted for 1 minute. Then, the discharged water was transferred to another container and weighed, the plastic composition was molded in the form of film using a roller and cured for 24 hours. Then, properties of the plastic composition and the cured substance were observed and are shown in the following Table 1.

(23) TABLE-US-00001 TABLE 1 Items Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Hydraulic Portland 40 g cement cement Plaster 40 g White cement 40 g Blast furnace 40 g slag cement Quick-setting 40 g cement Water 16 g 16 g 16 g 16 g 16 g Polyether polyol 8 g 8 g 8 g 8 g 8 g MDI 8 g 8 g 8 g 8 g 8 g Amount of discharged 10.7 g 0 g 2.0 g 5.5 g 8.1 g water Properties of plastic Excellent Weak Excellent Excellent Excellent composition adhesive aggregation plasticity adhesive adhesive property, property, property, excellent excellent excellent plasticity plasticity plasticity Properties of cured Excellent Low Low Medium Medium substance strength, strength, strength, strength, strength, excellent low excellent medium excellent hardness hardness hardness hardness hardness

(24) In addition, images were respectively obtained immediately after addition of polymeric MDI, after rapid stirring for 10 seconds, after slow stirring for 30 seconds and after slow stirring for 60 seconds in Example 1 and are shown in (A), (B), (C) and (D) of FIG. 1. As can be seen from FIG. 1, water is rapidly separated from the plastic composition via stirring.

(25) Meanwhile, FIG. 2 is an image showing a state seen from above the beaker after slow stirring for 60 seconds in Example 1 of the present invention. FIG. 2 clearly illustrates the mix composition of polyurethane and the cement paste and liquid-type free water separated, discharged and phase-separated from the mix composition, and FIG. 3 is an image showing the dense surface of a cured substance obtained by molding the composition obtained in Example 1 of the present invention in the form of a film using a roller and then curing the film.

(26) In addition, FIG. 4 is an image showing the surface of a cured substance obtained by molding the composition obtained in Example 2 of the present invention in the form of a film using a roller and then curing the same. As can be seen from FIG. 4, in a case in which plaster is used instead of hydraulic cement, polyurethane is released to the surface of the cured substance due to insufficient affinity of plaster to urethane.

(27) FIG. 5 is an image showing the surface of a cured substance obtained by molding the composition obtained in Example 3 of the present invention in the form of a film using a roller and then curing the same. As can be seen from FIG. 5, white cement with relatively large particles does not release polyurethane due to excellent affinity to urethane.

(28) As can be seen from Table 1 and FIGS. 1 to 5, in all cases excluding use of plaster, plastic compositions with excellent adhesive strength and plasticity are obtained, and the cured substances are excellent or medium in terms of either strength or hardness and are useful as good molding materials.

(29) It can be seen that, thereamong, Portland cement is excellent in terms of both plastic composition properties and cured substance properties.

Examples 6-11. Application of Combination of Hydraulic Cement

(30) Portland cement which was considered to have excellent strength and plaster or white cement which was considered to have bad strength in Examples 1 to 5 were mixed in a ratio shown in Table 2, 40 g of the mixture and 16 g of water were respectively added to 200 mL beakers and stirring was conducted for 30 seconds. 8 g of polyether polyol was added thereto, stirring was conducted for 30 seconds, 8 g of liquid polymeric MDI was added, rapid stirring was conducted for 10 seconds and slow stirring was conducted for 1 minute. Then, the discharged water was transferred to another container and weighed. The plastic composition obtained by separation of water was molded in the form of a film using a roller and cured for 24 hours and properties of the plastic composition and the cured substance were observed.

(31) TABLE-US-00002 TABLE 2 Items Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Hydraulic Portland 10 g 20 g 30 g 10 g 20 g 30 g cement cement Plaster 30 g 20 g 10 g White 30 g 20 g 10 g cement Water 16 g 16 g 16 g 16 g 16 g 16 g Polyether polyol 8 g 8 g 8 g 8 g 8 g 8 g MDI 8 g 8 g 8 g 8 g 8 g 8 g Amount of discharged 3 g 6 g 6.4 g 4.5 g 8.4 g 8.4 g water Properties of plastic Weak Weak Excellent Weak Excellent Excellent composition aggregation aggregation adhesive aggregation adhesive adhesive property property property Properties of cured Medium Medium Excellent Medium Excellent Excellent substance strength, strength, strength, strength, strength, strength, medium medium excellent medium medium excellent hardness hardness hardness hardness hardness hardness Release of polyurethane No No No No No No

(32) As can be seen from results shown in Table 2, when a great amount of plaster or white cement is mixed, aggregation of the plastic composition is slightly deteriorated and, strength or hardness of the cured substance is medium, but when the content of plaster or white cement is less than 50%, a cured substance with relatively excellent physical properties can be obtained.

Examples 12-29. Determination of Suitable Ratio Between Hydraulic Cement and Ingredient for Forming Foamed Urethane

(33) 40 g of Portland cement and 16 g of water were respectively added to 200 mL beakers, the resulting mixture was stirred for 30 seconds, polyether polyol and liquid polymeric MDI were sequentially added thereto while the amounts of added polyether polyol and liquid polymeric MDI were changed as shown in Table 3, and the discharged water was transferred to another container and weighed. In addition, the resulting plastic composition was molded in the form of a film using a roller and cured for 24 hours. Then, properties of the plastic composition and the cured substance were observed.

(34) TABLE-US-00003 TABLE 3 Amount of Properties of Polyether discharged plastic Properties of cured Items polyol MDI water composition substance Ex. 12 2 g 2 g 1 g Weak aggregation Low strength, medium hardness Ex. 13 3 g 3 g 3 g Weak aggregation Low strength, medium hardness Ex. 14 4 g 4 g 4.6 g Medium Medium strength, aggregation excellent hardness Ex. 15 5 g 5 g 8 g Medium adhesion Excellent strength, excellent hardness Ex. 16 6 g 6 g 12.2 g High adhesion Excellent strength, excellent hardness Ex. 17 7 g 7 g 13 g High adhesion Excellent strength, medium hardness Ex. 18 9 g 9 g 8.1 g High adhesion Excellent strength, medium hardness Ex. 19 10 g 10 g 7.6 g High adhesion Medium strength, medium hardness Ex. 20 11 g 11 g 8 g High adhesion Medium strength, medium hardness Ex. 21 12 g 12 g 6.1 g High adhesion Medium strength, medium hardness Ex. 22 13 g 13 g 6 g High adhesion Medium strength, medium hardness Ex. 23 14 g 14 g 5.7 g High adhesion Medium strength, medium hardness Ex. 24 15 g 15 g 7.5 g High adhesion Medium strength, medium hardness Ex. 25 16 g 16 g 7 g High adhesion Medium strength, medium hardness Ex. 26 17 g 17 g 4.6 g High adhesion Medium strength, low hardness Ex. 27 18 g 18 g 3 g High adhesion Medium strength, low hardness Ex. 28 19 g 19 g 3.2 g High adhesion Medium strength, low hardness Ex. 29 20 g 20 g 2 g High adhesion Medium strength, low hardness

(35) As can be seen from Table 3, as the contents of polyol and MDI, which are ingredients for forming foamable polyurethane, increase, the adhesive strength of the plastic composition is improved, whereas, when the contents are higher than a certain levels, strength and hardness of the cured substance are deteriorated.

(36) The mix ratio of the ingredient for forming foamable polyurethane that exhibits the best properties is determined to be 20 to 35 parts by weight, with respect to 100 parts by weight of the hydraulic cement.

Examples 30-34. Use of Polyester-Based Polyol as Ingredient for Forming Foamed Urethane

(37) 40 g of Portland cement and 16 g of water were respectively added to 200 mL beakers, the resulting mixture was stirred for 30 seconds, polyester polyol and liquid polymeric MDI were sequentially added thereto in amounts as shown in Table 4, and the discharged water was transferred to another container and weighed. In addition, the resulting plastic composition was molded in the form of a film using a roller and cured for 24 hours. Then, properties of the plastic composition and the cured substance were observed.

(38) TABLE-US-00004 TABLE 4 Items Ex. 30 Ex. 31 Ex. 32 Ex. 33 Ex. 34 Portland cement 40 g 40 g 40 g 40 g 40 g Water 16 g 16 g 16 g 16 g 16 g Polyether polyol 2 g 3 g 4 g 5 g 6 g MDI 2 g 3 g 4 g 5 g 6 g Amount of discharged 0 g 2 g 5 g 10.8 g 12.2 g water Properties of plastic No Low Medium Excellent Excellent composition aggregation aggregation aggregation adhesive adhesive property property Properties of cured Low Low Low Excellent Excellent substance strength, strength, strength, strength, strength, low low medium excellent excellent hardness hardness hardness hardness hardness

(39) In a case in which polyester-based polyol is used, like a case in which polyether polyol is used, a plastic composition with excellent adhesive strength and a cured substance with excellent physical properties can be obtained.

Examples 35-39. Review of Suitable Amount of Added Water

(40) 40 g of Portland cement was added to a 200 mL beaker, water and polyether polyol were added together thereto while changing the amount of added water as shown in Table 5, and stirring was conducted for 30 seconds. Then, 7 g of polymeric MDI was added and mixing properties were observed while mixing. Then, the discharged water was transferred to another container and weighed. In addition, the plastic composition obtained by separation of water was molded in the form of a film using a roller and cured for 24 hours. Then, properties of the plastic composition were observed.

(41) TABLE-US-00005 TABLE 5 Items Ex. 35 Ex. 36 Ex. 37 Ex. 38 Ex. 39 Portland cement 40 g 40 g 40 g 40 g 40 g Water 1 g 2 g 5 g 30 g 40 g Polyether polyol 7 g 7 g 7 g 7 g 7 g MDI 7 g 7 g 7 g 7 g 7 g Amount of discharged 0 g 0.8 g 1.5 g 19.3 g 12.2 g water Properties of mixing Bad Bad Bad Good Good workability workability workability workability workability Properties of plastic Foamed Excellent Excellent Low Impossible composition adhesive adhesive aggregation aggregation property property Properties of cured Medium Medium High Medium substance strength, strength, strength, strength, medium medium high medium hardness hardness hardness hardness

(42) As can be seen from Table 5, as the amount of added water increases, workability is good due to improved flowability, but adhesive property of the plastic composition or physical properties of the cured substance may be deteriorated, when the amount of added water is excessively high. The amount of added water as well as the amount of added ingredient for forming foamable polyurethane should be controlled depending on desired application.

Examples 40-45. Preparation of Composite Molded Substance

(43) 40 g of Portland cement and 16 g of water were respectively added to 200 mL beakers, the resulting mixture was stirred for 30 seconds, polyether polyol and liquid polymeric MDI were sequentially added thereto while the amounts of added polyether polyol and liquid polymeric MDI were changed as shown in Table 6, and the discharged water was transferred to another container and weighed. In addition, wood fiber, pulp, dry sand, ground waste paper, bran, aluminum hydroxide and glass fiber powder were added to the plastic composition obtained after separation of water, the ingredients were mixed and were molded in a die and cured for hours. Then, properties of the cured substance were observed.

(44) TABLE-US-00006 TABLE 6 Items Ex. 40 Ex. 41 Ex. 42 Ex. 43 Ex. 44 Ex. 45 Portland cement 40 g 40 g 40 g 40 g 40 g 40 g Water 16 g 16 g 16 g 16 g 16 g 16 g Polyether polyol 14 g 6 g 6 g 14 g 7 g 7 g MDI 14 g 6 g 6 g 14 g 7 g 7 g Amount of 6 g 11.4 g 10.5 g 3.8 g 10.1 g 9.5 g discharged water Mixed substance Wood Pulp Ground Bran Aluminum Glass (amount) fiber (0.77 g) waste (10 g) hydroxide fiber (20 g) paper (10 g) powder (1.2 g) (0.2 g) Properties of cured Excellent Improved Surface Surface Low Improved substance durability strength roughness roughness abrasion strength resistance

(45) As can be seen from Table 6, composite molded articles with various properties as well as a variety of fillers can be produced using the plastic composition according to the present invention.

(46) Meanwhile, FIG. 6 is an image showing a surface morphology of a composite molded article using a wood fiber obtained in Example 40 of the present invention.

(47) Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appropriate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.