JPH05305608A - Peeling agent for concrete shuttering - Google Patents

Abstract

PURPOSE:To obtain a peeling agent of a concrete shuttering which reduces generation of bubbles on the surface of concrete and is superior in peeling properties from the concrete shuttering, by a method wherein alkyl ketene dimer and a nonionic surface active agent represented by a specific formula are compounded with a liquid water repellent substance. CONSTITUTION:A liquid water repellent substance such as mineral oil, animal and plant oil, oils and fats, fatty acid, silicone oil and praffin oil are used for this peeling agent of a concrete shuttering as base oil and the peeling agent of the concrete shuttering is prepared by compounding alkyl ketene dimer and a nonionic surface active agent represented by a general formula as mentioned on the right side with the liquid water repellent substance. The alkyl ketene dimer is obtained by reaction between fatty acid chloride and triethyl amine, in the formula, R represents 12-22C straight chain or branch chain alkyl group and the 3-10wt.% alkyl ketene dimer is compounded with the liquid water repellent substance. Then a matter whose HLB value is within 8-12 is used for the nonionic surface active agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface aesthetic improving mold remover for concrete which is excellent in reducing bubbles generated on the surface of concrete.

[0002]

2. Description of the Related Art Conventionally, mold release agents for concrete are mainly composed of mineral oil or animal and vegetable oil, and there are two types, an oily type and an aqueous type. It is well known that the release agent effective for reducing surface bubbles is generally the latter aqueous type.

[0003]

Aqueous-type release agents are those which have been diluted with water to be emulsified or already emulsified. To improve the emulsion stability of these, the affinity for water (hydrophilicity) is increased. ing. However, the high affinity makes it easier to adapt to the concrete when it is placed, and has the disadvantage of increasing the contact angle. Therefore, the mold releasability of the concrete is deteriorated, the peeling becomes difficult, and the adhesion of the concrete to the form becomes a problem.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have earnestly studied in order to reduce air bubbles generated on the surface of concrete and to obtain a water-dilutable release agent excellent in releasability. , The specific water-repellent alkyl ketene dimer is solubilized in the oil component to strengthen the release film, improving the drawbacks of conventional water-based release agents, and significantly reducing the bubbles generated on the concrete surface. As a result, they have completed the present invention.

That is, the present invention provides a mold releasing agent for concrete, which is characterized in that a liquid water-repellent substance is mixed with an alkyl ketene dimer represented by the following general formula and a nonionic surfactant. is there.

[0006]

[Chemical 2]

[In the formula, R represents a linear or branched alkyl group having 12 to 22 carbon atoms. The liquid water-repellent substance used as the base oil of the present invention is mineral oil or animal / vegetable oil, oil / fat, fatty acid, silicone oil, paraffin oil, etc., and is not limited.

The alkyl ketene dimer represented by the above general formula is obtained by the reaction of a fatty acid chloride and triethylamine. The alkyl group of the fatty acid represented by R has 12 to 22 carbon atoms. An example of the fatty acid chloride is: Examples thereof include lauric acid chloride, myristic acid chloride, palmitic acid chloride, stearic acid chloride and behenic acid chloride. Such an alkyl ketene dimer is excellent in mold releasability of concrete when blended in an amount of 3 to 10% by weight with respect to the liquid water-repellent substance. If the amount of the alkyl ketene dimer is less than 3% by weight, no sufficient effect can be seen, and if it exceeds 10% by weight, the alkyl ketene dimer cannot be solubilized.

The nonionic surfactant used in the present invention is for solubilizing the liquid water-repellent substance and the alkyl ketene dimer and further emulsifying when diluted with several times of water at the time of use, The structure of the nonionic surfactant is not particularly limited. As an example of the nonionic surfactant, polyoxyethylene alkyl ether,
Polyoxyethylene alkyl phenyl ether, sorbitan fatty acid ester, fatty acid monoglyceride, polyethylene glycol fatty acid ester and the like can be used alone or in combination of two or more kinds. Further, in the present invention, a nonionic surfactant having an HLB value in the range of 8 to 12 can obtain a good solubilized state and an emulsified state when diluted with water and can be preferably used. Examples of such nonionic surfactants are polyoxyethylene lauryl ether (ethylene oxide (hereinafter abbreviated as EO) addition mole number 6 moles, HLB10.5), polyoxyethylene nonylphenyl ether (EO Addition mole number 8 moles, HLB
10.5), sorbitan monolaurate (HLB 8.6),
Polyoxyethylene sorbitan monolaurate (3 moles of EO addition, HLB 9.6), polyoxyethylene sorbitan trioleate (6 moles of EO addition, HLB 11.
0) and the like. The addition amount of the nonionic surfactant is about 3 to 8% by weight with respect to the liquid water-repellent substance, but it is not limited as long as it is in the range where a solubilized state and an emulsified state can be obtained.

The mold remover for concrete of the present invention is used by diluting it with water 3 to 20 times, but it is also possible to use an undiluted solution.

The method of applying the mold releasing agent for concrete of the present invention to the mold is not limited, and any method such as mopping or spraying can be used. Also, the material of the mold is not limited.

The concrete using the mold remover for concrete of the present invention is not limited to civil engineering, construction, secondary products, etc., but concrete using a mold is targeted. The same applies to types of concrete, from zero-slump cemented concrete to high-fluidity concrete,
For example, it can be used for vibration-free concrete or the like.
Therefore, the mixing conditions and materials of concrete are not limited, and various admixtures (agents) such as fly ash, slag, silica fume, high-performance water reducing agent, A
It can be used for concrete containing E agent, water-soluble polymer and the like.

[0013]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The stripping agent shown in Table 1 or Table 2 was applied to the vertical 10 cm × horizontal direction.
Apply it to an iron mold of 10 cm x 20 cm in height and pour concrete. At the time of placing, it is vibrated and filled with a 3000vpm table type vibrator for 20 seconds. Two days after the casting, the mold was removed and the surface condition of the concrete and the mold condition were observed. The material, composition and physical properties of the concrete used, and each evaluation method are shown below. (1) concrete material, formulation and physical property materials Cement (C): ordinary Portland cement specific gravity = 3.16 Sand (S): Kinokawa producing specific gravity = 2.56 gravel (G): Takarazuka producing crushed stone specific gravity = 2.60 Water (W): Water water admixture: Mighty 150 (registered trademark, manufactured by Kao Corp.) formulation W / C × 100: 40% S / (S + G) × 100: 40% C: 400 kg / m 3 admixture: C × 1.2% properties Slump value: 10 cm (JIS-A-1101 method) (2) Measurement of surface state (air bubbles) The number of air bubbles of 1 mm or more in 200 cm ^{2 of} 10 cm × 20 cm was measured. (3) Observation of releasability (dirt of mold) The state of adhesion of concrete to the surface of the demolded mold was observed. Judgment criteria XX: Thickly attached to the entire surface of the mold X: Partially thickly attached △: Thinly attached to the entire surface of the form ◯: Partially thinly attached ◎: No attachment

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

As is apparent from the examples, the mold release agent for concrete of the present invention exhibits excellent aesthetics and releasability by reducing surface bubbles. Therefore, the labor required for surface repair and form cleaning can be saved, and quality improvement is expected.

Claims (3)

[Claims] 1. A mold releasing agent for concrete, comprising a liquid water-repellent substance and an alkylketene dimer represented by the following general formula and a nonionic surfactant. [Chemical 1] [In the formula, R represents a linear or branched alkyl group having 12 to 22 carbon atoms. ] 2. The mold releasing agent for concrete according to claim 1, wherein the alkyl ketene dimer represented by the above general formula is blended in an amount of 3 to 10% by weight with respect to the liquid water-repellent substance. 3. The HLB value of the nonionic surfactant is from 8 to.
The mold release agent for concrete according to claim 1 or 2, which has a range of 12.