JP2001048676A - Concrete curing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to obtain high strength and smooth surface by consisting a water absorptive material to be laminated between a water permeable material and a water impermeable material of denatured matter of polyalkylene oxide. SOLUTION: This concrete curing sheet is formed by laminating the denatured matter of the polyalkylene oxide obtained by reaction of polyalkylene oxide and polyol with an isocyanate compound between the water permeable material and the water impermeable material. The melting viscosity under loading of 4.9 MPa at 170 deg.C of the denatured matter of the polyalkylene oxide is preferably 50 to 5000 Pa.S and the water absorptivity (g pure water/g resin) thereof is 5 to 46 g/g. The polyalkylene oxide has preferably a weight average molecular weight of 500 to 500,000 and includes, for example, polyethylene oxide, or the like. The polyol is preferably ethylene glycol, or the like, and the isocyanate compound is preferably 1,6-hexamethyhlene diisocyanate, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a concrete curing sheet. More specifically, the present invention relates to a concrete curing sheet used to obtain high-strength concrete having a smooth surface in a method for moist curing concrete cast in civil engineering construction work.

[0002]

2. Description of the Related Art When concrete is poured in civil engineering and construction work, if the mold is removed at an early stage, the moisture evaporates rapidly, causing drying and shrinkage. Problems such as poor surface smoothness occur. However, if the mold is left set for a long period of time, the rotation rate of the mold is reduced and the cost is increased. Therefore, after the mold is removed from the construction site at an early stage, drying is prevented by water spraying or the like. However, there is a problem that it is necessary to spray water many times during the curing period, and it is difficult to spray water on a wall surface or a ceiling.

On the other hand, as a measure for preventing drying, a concrete curing sheet using a composite material of a highly water-absorbent resin and a nonwoven fabric has been proposed (Japanese Patent Application Laid-Open No. 63-70765).
However, these superabsorbent resins generally do not have thermoplasticity, so it is difficult to form a single resin into a sheet, film, or the like. Therefore, although a sandwich structure is formed between the nonwoven fabrics, there are problems in the method of dispersing and fixing the superabsorbent resin. In addition, the water-absorbent resin has a problem that the water-absorbing ability is extremely lowered in water containing metal ions and the like, and a concrete curing sheet using the super-water-absorbent resin has a sufficient curing effect due to insufficient water absorption. Not.

[0004] Therefore, a concrete curing sheet which can be freely formed and has excellent water absorption performance which can be used for civil engineering and construction work is desired. As such a concrete curing sheet, for example, a composite sheet comprising a water-absorbing resin material obtained by crosslinking a water-soluble resin containing ethylene oxide as a main component with an electron beam, and a hydrophobic synthetic resin material has been proposed (see, for example, Japanese Patent Application Laid-Open No. H11-157572). JP-A-8-60867). However, in the above-mentioned method, when crosslinking with an electron beam, it is necessary to perform treatment in an oxygen-free state, and there is a limitation on the thickness of the sheet. Further, the water absorption ability is reduced and the elution amount is increased due to the variation in the degree of crosslinking, and there is still room for improvement.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a concrete curing sheet capable of obtaining high-strength, smooth-surface concrete in a method for wet curing of concrete cast in civil engineering and construction work. I do.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a concrete cured sheet comprising a water-absorbing material laminated between a water-permeable material and an impermeable material. The present inventors have found that a concrete curing sheet made of a specific water-absorbing material can solve the above-mentioned problems, and completed the present invention. That is, the present invention provides a concrete cured sheet obtained by laminating a water-absorbing material between a water-permeable material and an impermeable material, wherein the water-absorbing material is obtained by reacting a polyalkylene oxide and a polyol with an isocyanate compound. And a concrete curing sheet comprising a modified polyalkylene oxide.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The water-absorbing material used in the present invention includes a modified polyalkylene oxide obtained by reacting a polyalkylene oxide and a polyol with an isocyanate compound. The modified polyalkylene oxide has a melt viscosity at 170 ° C and a load of 4.9 MPa of 50 to 5000 Pa · S, preferably 100 to 3000 Pa · S, and more preferably 150 to 5,000 Pa · S.
2000 Pa · S, water absorption capacity (g pure water / g resin) is 5
A resin of 45 g / g, preferably 15 to 45 g / g, more preferably 20 to 45 g / g is suitably used.

[0008] When the melt viscosity is less than 50 Pa · S or when the water absorption capacity exceeds 45 g / g, undesirably, the amount of leaching increases and a slimy feeling is produced on the surface of the concrete curing sheet. When the melt viscosity exceeds 5000 Pa · S and when the water absorption capacity is less than 5 g / g, the moldability deteriorates and the water absorption decreases.

As the polyalkylene oxide constituting the modified polyalkylene oxide, those having a weight average molecular weight of 500,000 to 500,000 are used. Examples thereof include polyethylene oxide, polypropylene oxide, ethylene oxide / propylene oxide copolymer, and polybutylene. Oxides and mixtures thereof can be mentioned. In particular, polyethylene oxide, polypropylene oxide having a weight average molecular weight of 2,000 to 100,000, a mixture thereof, or a copolymer thereof is preferably used. If the weight average molecular weight is less than 500, the resulting polyalkylene oxide-modified product is undesirably increased in the amount of elution, causing a slimy feeling on the surface of the concrete curing sheet. If the weight average molecular weight exceeds 500,000, the melt viscosity becomes extremely high, moldability is deteriorated, and the water absorption is undesirably reduced.

[0010] The polyol constituting the modified polyalkylene oxide together with the polyalkylene oxide includes:
Organic compounds having two hydroxyl groups (-OH) in the same molecule, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol,
Trimethylene glycol, 1,3-butanediol,
2,3-butanediol, 1,4-butanediol,
1,5-pentanediol, hexylene glycol, octylene glycol, glyceryl monoacetate, glyceryl monobutyrate, 1,6-hexanediol,
Examples thereof include 1,9-nonanediol and bisphenol A. Among them, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol and the like are preferably used.

As the isocyanate compound used for crosslinking the polyalkylene oxide and the polyol, an organic compound having two or more isocyanate groups in the same molecule, for example, dicyclohexylmethane-4,
4′-diisocyanate (HMDI), xylylene diisocyanate (XDI), 4,4′-diphenylmethane diisocyanate (MDI), 1,6-hexamethylene diisocyanate (HDI), 1,8-dimethylbenzol-2,4-diisocyanate, Urethane isocyanate compound obtained by reacting 2,4-tolylene diisocyanate (TDI), a trimer of TDI, a polyol such as polymethylene polyphenyl isocyanate, trimethylolpropane and the like with a mole number of diisocyanates corresponding to the number of active hydrogens And polyisocyanate adducts. Among them, 1,6-hexamethylene diisocyanate (HDI), dicyclohexylmethane-
4,4'-diisocyanate (HMDI), 4,4'-
Diphenylmethane diisocyanate (MDI), 2,4
-Tolylene diisocyanate (TDI) and the like are preferably used. In particular, when weather resistance and water resistance are required,
6-hexamethylene diisocyanate (HDI), dicyclohexylmethane-4,4'-diisocyanate (H
MDI) is preferably used.

The proportion of the polyalkylene oxide to the polyol and the isocyanate compound is determined by the ratio (R value) of the sum of the number of terminal hydroxyl groups of the polyalkylene oxide to the number of hydroxyl groups of the polyol and the number of isocyanate groups of the isocyanate compound. NCO group / -OH group) in a range of 0.5 to 2.0, preferably 0.8 to 1.
7 is selected. When the R value is less than 0.5,
Since the crosslink density is low, it becomes water-soluble, and the surface state after water absorption deteriorates. On the other hand, when the R value exceeds 2.0, the crosslinking density is increased, and the melt viscosity is increased, so that the moldability is deteriorated.

The amount of the isocyanate compound used varies depending on the type of the isocyanate compound and the reaction conditions.
0.5 to 80 parts by weight, preferably 1 to 100 parts by weight
The range is from 50 to 50 parts by weight. If the amount is less than 0.5 part by weight, the cross-linking density of the resulting polyalkylene oxide-modified product will be low, and the strength required for the concrete curing sheet will not be obtained. On the other hand, if it exceeds 80 parts by weight, it will be obtained. It is not preferable because the crosslink density of the modified polyalkylene oxide becomes too high and moldability deteriorates.

As a method of reacting a polyalkylene oxide and a polyol with an isocyanate compound, a method of reacting in a solution using a suitable solvent is generally used. A method of reacting in a dispersed state, or a method in which both are uniformly mixed in a powder or solid state and then heated to a predetermined temperature and then reacted, but from the viewpoint of industrial practice, each raw material is continuously melted. A method of feeding, mixing and reacting in a multi-screw extruder is preferred.

[0015] The reaction temperature is usually 70 to 210 ° C. The reaction can be promoted by adding a small amount of triethylamine, triethanolamine, dibutyltin diacetate, dibutyltin dilaurate, stannasoctoate, triethylenediamine, or the like to this reaction system.

The water-permeable material used in the present invention includes:
The material is not particularly limited as long as it is a water-permeable material, and examples thereof include a nonwoven fabric, a woven fabric, a perforated film or paper made of a polyethylene resin, a polypropylene resin, a polyvinyl chloride resin, a polyester resin, a polyurethane resin, a polyamide resin, and the like. Among these, a nonwoven fabric, a woven fabric, or a perforated film made of at least one selected from the group consisting of polyethylene resin, polypropylene resin, and polyester resin, which can be heat-fused and can be removed from concrete, is preferably used. Can be The thickness of the water-permeable material is usually 10 to 200 μm, preferably 20 to 100 μm.
m.

The water-impermeable material used in the present invention is not particularly limited as long as it is a water-impermeable material. Examples of the water-impermeable material include polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyester resin, polyurethane resin and polyamide resin. And the like. Among them, a film made of at least one selected from the group consisting of polyethylene resin, polypropylene resin, polyester resin and polyurethane resin is preferably used from the viewpoint of thermoplasticity and economy. The thickness of the water-impermeable material is 10 to 100 μm, preferably 20 to 50 μm.
It is.

The shape of the water-absorbing material used in the present invention is not particularly limited, but a polyalkylene oxide-modified product formed into a film, powder, chip, fiber or the like is preferably used. The thickness of the water absorbing material is not particularly limited, but is usually 20 to 200 μm, preferably 50 to 150 μm.
μm. If the thickness of the water-absorbing material is less than 20 μm, the amount of liquid absorption will be insufficient, and if it exceeds 200 μm, it will protrude from the substrate after absorbing the liquid, which is not preferable in terms of economy. The concrete curing sheet of the present invention is obtained by laminating a water-permeable material, a modified polyalkylene oxide, and a water-impermeable material from the side in contact with concrete.

The method for producing the concrete-cured sheet of the present invention is not particularly limited. Since the polyalkylene oxide-modified product and the water-impermeable material have thermoplasticity, they can be formed by heat extrusion such as co-extrusion lamination, heat lamination, and press molding. Manufactured by processing. For example, after extruding a polyalkylene oxide-modified product and a water-impermeable material onto a water-permeable material with an extruder equipped with a composite die, a method of partially fusing and bonding with an embossing roll or the like, formed into a film shape. Polyalkylene oxide modified product, a method of laminating a water-permeable material and a water-impermeable material, and then partially fusing them with an embossing roll or the like, laminating the powder, a chip, a fiber-modified polyalkylene oxide product or the like Is spread on a water-permeable material, and then a water-impermeable material is overlapped, partially fused with an embossing roll or the like, and bonded. Further, if necessary, a primer layer can be provided for the purpose of increasing the adhesive strength between the dry laminating adhesive and the material. Further, each material constituting the concrete curing sheet of the present invention may contain additives such as a plasticizer, a surfactant, a stabilizer, a filler, and a coloring agent, if desired.

[0020]

EXAMPLES The present invention will be described in more detail with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples. The polyalkylene oxide-modified product or the concrete cured sheet obtained in Production Examples, Examples and Comparative Examples was evaluated by the following method.

1. Test items of polyalkylene oxide-modified product and method thereof (1) Water absorption capacity [g (pure water) / g (resin)] 1 g of polyalkylene oxide-modified product was added to 200 ml of pure water, and stirred for 24 hours. The gel was filtered through a wire mesh, and the weight of the gel after the filtration was taken as the water absorption capacity. (2) Melt viscosity (Pa · S) Die 1 mmφ under the conditions of 170 ° C. and 4.9 MPa load
× 1mmL orifice (Flow Tester C manufactured by Shimadzu Corporation)
FT-500C).

2. Test items and method for concrete curing sheet (1) Liquid absorption (g / m ² ) A concrete curing sheet was cut into a size of 100 mm x 100 mm, and a cement component extract (portland cement / water = 1/1 weight ratio) ) For 24 hours and the weight before immersion (W0), the liquid absorption was determined by the following equation. Liquid absorption (g / m ² ) = (W1−W0) /0.01 (2) Compression test After a curing sheet is attached to the bottom and inner surfaces of a concrete formwork (15φ × 20 cm), the concrete (water) 180k
g / m ³ , cement 360 kg / m ³ , fine aggregate 844 kg
/ M ³ , coarse aggregate 990 kg / m ³ , coarse aggregate maximum dimension 20 m
m), the surface was leveled, and a curing sheet was stuck on the upper part. After 14 days at room temperature, the mold was removed, and after standing for 14 days, the strength was measured. (3) Surface Condition The surface condition of the concrete before the strength measurement was visually observed. The evaluation criteria for the surface state are as follows. ：: Good in dense surface condition ×: Many pock and bubbles on the surface

Production Example 1 100 parts by weight of sufficiently dehydrated polyethylene oxide having a weight average molecular weight of 20,000 and ethylene oxide / propylene oxide having a weight average molecular weight of 15,000 (= 80/2)
0) 100 parts by weight of the copolymer, 1.26 parts by weight of 1,4-butanediol, and 0.1 part by weight of dibutyltin dilaurate were put into a storage tank A having a stirrer kept at 70 ° C., and a nitrogen gas atmosphere was added. A homogeneous mixture was obtained below. Separately, dicyclohexylmethane-4,4'-diisocyanate was placed in a storage tank B equipped with a stirrer kept at 30 ° C and stored under a nitrogen gas atmosphere.

The mixture in the storage tank A and the dicyclohexylmethane-4,4'-diisocyanate in the storage tank B were twin-screw extruded at 170 to 200 ° C. at a rate of 250 g / min and 8.35 g / min by a metering pump, respectively. The mixture was continuously supplied to an extruder, mixed and reacted by an extruder, and a strand was discharged from an extruder outlet, and pelletized by a pelletizer to obtain a modified polyalkylene oxide. The melt viscosity of the polyalkylene oxide-modified product thus obtained (170 ° C.,
4.9 MPa) was 2000 Pa · S, and the water absorption capacity was 40 g / g.

Production Example 2 100 parts by weight of sufficiently dehydrated polyethylene oxide having a weight average molecular weight of 20,000 and 1,4-butanediol 0.1%
9 parts by weight, 0.02 parts by weight of dibutyltin dilaurate,
The mixture was placed in a storage tank A equipped with a stirrer kept at 70 ° C., and a uniform mixture was obtained under a nitrogen gas atmosphere. Separately, dicyclohexylmethane-4,4'-diisocyanate was placed in a storage tank B equipped with a stirrer kept at 30 ° C and stored under a nitrogen gas atmosphere.

The mixture in storage tank A and the dicyclohexylmethane-4,4'-diisocyanate in storage tank B were metered using a metering pump at rates of 333 g / min and 13 g / min, respectively.
The mixture was continuously supplied to a twin-screw extruder set at 170 to 200 ° C., mixed and reacted by the extruder, and a strand was discharged from the outlet of the extruder, and pelletized by a pelletizer to obtain a modified polyalkylene oxide. The melt viscosity of the polyalkylene oxide-modified product thus obtained (170 ° C., 4.
9 MPa) is 300 Pa · S, and the water absorption capacity is 22 g.
/ G.

Production Example 3 50 parts by weight of sufficiently dehydrated polyethylene oxide having a weight average molecular weight of 11,000, and ethylene oxide / propylene oxide having a weight average molecular weight of 15,000 (= 80/20)
50 parts by weight of a copolymer, 0.85 of 1,4-butanediol
Parts by weight, 0.1 parts by weight of dibutyltin dilaurate and 300 parts by weight of toluene were placed in a reaction vessel having a stirrer kept at 110 ° C. to form a uniform mixed solution under a nitrogen gas atmosphere. Dicyclohexylmethane-4,4'-
5.45 parts by weight of diisocyanate was added and reacted for 3 hours. After completion of the reaction, hexane was added, and the mixture was cooled to room temperature to precipitate the formed resin. This slurry was filtered under pressure and dried under reduced pressure to obtain a modified polyethylene oxide. The melt viscosity (170 ° C., 4.9 MPa) of the polyalkylene oxide-modified product thus obtained is 3500 P
a · S, and the water absorption capacity was 30 g / g.

Example 1 Non-woven fabric (PP / PET, thickness 80 μm) as a water-permeable material
m, manufactured by Rengo Non Woven Products Co., Ltd.), the polyalkylene oxide-modified product obtained in Production Example 1 as a water-absorbing material, and a polyethylene resin (trade name: Sumikasen L705, Sumitomo Chemical Co., Ltd.) as a water-impermeable material. )) Was used. Using a single screw extruder equipped with a composite die of the polyalkylene oxide-modified product and the polyethylene resin, the polyalkylene oxide-modified product is 150 μm at a temperature of 150 ° C.
m, extruded onto the non-woven fabric so that the polyethylene resin became 20 μm, and embossed roll (20 × 20 mm
(A corner, a line width of 2 mm) was partially fused and bonded to obtain a concrete cured sheet of the present invention. Using the obtained concrete-cured sheet, the above (1) liquid absorption, (2) compression test, and (3) surface state performance evaluation were performed. (1)-
Table 1 shows the results of (3).

Example 2 Nonwoven fabric (PE / PP, thickness 100 μm) as a water permeable material
m, manufactured by Rengo Non Woven Products Co., Ltd.), the polyalkylene oxide modified product obtained in Production Example 2 was used as a water-absorbing material, and a commercially available polyethylene film (25 μm thick) was used as a water-impermeable material. A film of the modified polyalkylene oxide having a thickness of 100 μm was obtained by inflation molding. The obtained film, the polyethylene film and the nonwoven fabric are superimposed, partially fused at a temperature of 170 ° C. using an embossing machine (20 × 20 mm square, line width 2 mm), and bonded together. I got The performance evaluation of the above (1) to (3) was performed using the obtained concrete curing sheet. The results are shown in Table 1.

Example 3 Nonwoven fabric (PE / PP, thickness 90 μm,
The polyalkylene oxide modified product obtained in Production Example 3 was used as a water-absorbing material, and a commercially available polyethylene film (25 μm in thickness) was used as a water-impermeable material. Press molding thickness 1
A film of the polyalkylene oxide-modified product having a thickness of 00 μm was obtained. The obtained film, the polyethylene film and the non-woven fabric are superimposed, and an embossing machine (20 ×
(20 mm square, 2 mm line width) and partially bonded at a temperature of 170 ° C to obtain a concrete cured sheet of the present invention. The performance evaluation of the above (1) to (3) was performed using the obtained concrete curing sheet. The results are shown in Table 1.

Comparative Example A nonwoven fabric (PE / PP, thickness 100 μm) was used as a water-permeable material.
m, manufactured by Rengo Non-Woven Products Co., Ltd.) and a polyacrylic acid-based highly water-absorbent resin (trade name: Aqua Keep 10SH-P, manufactured by Sumitomo Seika Co., Ltd.) as a water-absorbing material.
A commercially available polyethylene film (25 μm in thickness) was used as the water-impermeable material. 100 g / m ² of a polyacrylic acid-based superabsorbent resin was sprayed on the non-woven fabric, and the polyethylene film was superimposed on the non-woven fabric.
(m square, line width: 2 mm) and partially cured at a temperature of 170 ° C to obtain a concrete cured sheet. The performance evaluation of the above (1) to (3) was performed using the obtained concrete curing sheet. The results are shown in Table 1.

[0032]

[Table 1]

From the results shown in Table 1, the concrete-cured sheets obtained in Examples 1 to 3 have a good absorption of the cement extract, and the concrete using the concrete-cured sheets obtained in Examples 1 to 3 It can be seen that the compressive strength is high and the surface condition is good.

[0034]

According to the present invention, it is possible to provide a concrete curing sheet used for obtaining concrete having a high strength and a smooth surface in a wet curing method for concrete cast in civil engineering and construction work.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Naoyuki Hashimoto 1-family, Irifune-cho, Himeji-shi, Hyogo Pref. DE02 DG03 DG04 DG09 DG10 HA01 HA07 HC03 HC12 HC17 HC22 HC46 HC52 HC61 HC64 HC71 JA02 JA14 JA32 QA05 QB04 QC06 QD01 QD04 RA10

Claims (9)

[Claims] 1. A concrete curing sheet obtained by laminating a water-absorbing material between a water-permeable material and a water-impermeable material,
A concrete curing sheet characterized in that the water-absorbing material comprises a modified polyalkylene oxide obtained by reacting a polyalkylene oxide and a polyol with an isocyanate compound. 2. The concrete curing sheet according to claim 1, wherein the thickness of the water-absorbing material is 20 to 200 μm. 3. The concrete curing sheet according to claim 1, wherein the modified polyalkylene oxide has a water absorption capacity of 5 to 45 g (pure water) / g (resin). 4. A polyalkylene oxide modified 170
The melt viscosity at a load of 4.9 MPa is 50 to 50 ° C.
The concrete curing sheet according to any one of claims 1 to 3, which is 00 Pa · S. 5. The polyalkylene oxide is at least one selected from the group consisting of polyethylene oxide, polypropylene oxide and ethylene oxide / propylene oxide copolymer having a weight average molecular weight of 500 to 500,000. Item 2. The concrete curing sheet according to item 1. 6. The polyol is ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-
The concrete curing sheet according to any one of claims 1 to 5, wherein the sheet is at least one selected from the group consisting of hexanediol and 1,9-nonanediol. 7. The at least one isocyanate compound selected from the group consisting of 1,6-hexamethylene diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 4,4′-diphenylmethane diisocyanate and 2,4-tolylene diisocyanate. The concrete curing sheet according to any one of claims 1 to 6, which is one kind. 8. The method according to claim 1, wherein the water-permeable material is at least one kind of nonwoven fabric, woven fabric or perforated film selected from the group consisting of polyethylene resin, polypropylene resin and polyester resin. Concrete curing sheet. 9. The concrete curing method according to claim 1, wherein the water-impermeable material is at least one film selected from the group consisting of a polyethylene resin, a polypropylene resin, a polyester resin, and a polyurethane resin. Sheet.