JP2951796B2 - Mold release agent for concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold release agent for concrete with improved surface appearance which is excellent in reducing bubbles generated on the concrete surface.

[0002]

2. Description of the Related Art Conventionally, a release agent applied to a concrete mold is mainly composed of a liquid water-repellent substance such as mineral oil or animal or vegetable oil, and there are two types, an oil type and a water type. It is well known that a release agent effective for reducing surface bubbles is generally the latter aqueous type.

[0003]

The aqueous type release agent is diluted with water and emulsified or already in an emulsified state, and has an affinity (hydrophilicity) with water in order to improve the emulsion stability. Is increasing. However, a high affinity has a disadvantage that the material is easily adapted to the concrete at the time of casting and the contact angle becomes large, so that the adhesive force of the release agent applied to the formwork is weakened and moves into the concrete. Therefore, the releasability of the concrete is deteriorated, the peeling becomes difficult, and the adhesion of the concrete to the formwork is a problem.

[0004]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies in order to reduce bubbles generated on the concrete surface and to obtain a water-dilutable release agent excellent in releasability. The adhesion of the release film to the mold is achieved by solubilizing an unsaturated fatty acid having 10 to 22 carbon atoms or an organic salt thereof having one or two OH groups having strong adhesion to the mold in an oil component. The present invention has been found to be strong, to improve the drawbacks of the conventional aqueous release agent, and to remarkably reduce air bubbles generated on the concrete surface, thereby completing the present invention.

That is, according to the present invention, OH
It is intended to provide a mold release agent for concrete, characterized by comprising an unsaturated fatty acid having 10 to 22 carbon atoms having one or two groups or an organic salt thereof and a nonionic surfactant. .

[0006] The unsaturated fatty acid having one or two OH groups or an organic salt thereof, which is compounded in the present invention, reacts with Ca or Si of the cement component present on the surface of the mold to form a metal salt, thereby forming a chemical adhesive force. Has been found to be effective for peeling concrete form because the number of reaction points of OH groups and COOH groups present in the molecule is large.

The position of the OH group in the molecule of the unsaturated fatty acid having one or two OH groups used in the present invention may be other than the terminal of the carbon chain, and does not limit the addition position. As the organic salt of the unsaturated fatty acid, it is preferable to use oil-soluble salts of a monoethanolamine salt, a diethanolamine salt, a triethanolamine salt, and a morpholine salt. Such unsaturated fatty acids having one or two OH groups or organic salts thereof can be used alone or in combination of two or more with respect to the liquid water repellent substance.
When it is blended in an amount of up to 10% by weight, the release property of concrete is excellent.

When the amount of the unsaturated fatty acid having one or two OH groups or the organic salt thereof is less than 3% by weight, no sufficient effect is obtained, and when the amount exceeds 10% by weight, the unsaturated fatty acid or its unsaturated salt is used. The salt cannot be solubilized.

The unsaturated fatty acid having one or two OH groups of the present invention has about 10 to 22 carbon atoms, such as dihydroxycaproleic acid, dihydroxyundecylenic acid, dihydroxyfisthenic acid, dihydroxyoleic acid,
Dihydroxy erucic acid, dihydroxy linoleic acid and the like can be mentioned.

The nonionic surfactant used in the present invention comprises a liquid water-repellent substance and an unsaturated fatty acid having one or two OH groups or an organic salt thereof in a solubilized state. This is for emulsification when diluted with water, and the structure of the nonionic surfactant is not particularly limited. Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, sorbitan fatty acid ester, fatty acid monoglyceride, polyethylene glycol fatty acid ester, and the like, either alone or in combination of two or more. Is possible. 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 upon dilution with water, and can be preferably used. As an example of such a nonionic surfactant, polyoxyethylene lauryl ether (ethylene oxide (hereinafter abbreviated as EO), the number of moles added: 6 mol, H
LB 10.5), polyoxyethylene nonyl phenyl ether (EO added 4 mol, HLB 8.6 or EO added 8 mol, HLB 11.2), sorbitan monolaurate (HLB 8.6), polyoxyethylene sorbitan monolaurate (EO Addition mole number 3 mol, HLB 9.6), polyoxyethylene sorbitan triolate (EO addition mole number 6)
Mol, HLB 11.0) and the like. The addition amount of the nonionic surfactant is 3 to 8% by weight based on the liquid water repellent substance.
Although the degree is preferable, the degree is not limited as long as it is in a range where a solubilized state and an emulsified state can be obtained. Also, the material of the mold is not limited.

The mold release agent for concrete of the present invention is used after being diluted 3 to 20 times with water, but a stock solution can also be used.

The method of applying the mold release agent for concrete of the present invention to the form can be any method such as mop coating or spraying, and is not limited. Also, the material of the mold is not limited.

[0013] The concrete using the mold release agent for concrete of the present invention is not limited to civil engineering, construction, secondary products, etc., but includes concrete using a form. The same applies to types of concrete, from zero-slump ultra-hard concrete to high-fluid concrete,
For example, it can be used for non-vibration concrete and 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.

[0014]

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

[0015] A release agent shown in Table 1 or Table 2
It is applied to an iron formwork of 10cm x 20cm height and cast concrete. Vibration filling with 3000vpm table type vibrator for 20 seconds at the time of casting. Two days after casting, the mold was removed and the surface condition of the concrete and the form condition were observed. Table 3 shows the evaluation results of the number of foams on the surface and the releasability. The concrete material, composition and physical properties used, and each evaluation method are as follows. (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): Tap water miscible agent: 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% physical slump : 10 cm (JIS-A-1101 method) (2) Measurement of surface condition (bubbles) The number of bubbles of 1 mm or more in 200 cm ^{2 of} 10 cm × 20 cm was measured. (3) Observation of peelability (dirt of mold) The state of adhesion of concrete to the mold surface of the mold was observed. Judgment criteria XX: Thickly adheres to the entire surface of the mold X: Partially adheres to the thickness △: Adheres thinly to the entire surface of the mold ○: Partially adheres thinly ◎: No adherence

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

As is clear from the examples, the mold release agent for concrete according to the present invention exhibits excellent effects on aesthetics and releasability by reducing surface bubbles. Therefore, labor required for surface repair and form cleaning can be saved, and improvement in quality is also expected.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B28B 7/38 B28B 1/14

Claims (5)

(57) [Claims] 1. A concrete comprising a liquid water-repellent substance mixed with an unsaturated fatty acid having 10 to 22 carbon atoms having one or two OH groups or an organic salt thereof and a nonionic surfactant. Mold release agent for 2. The concrete mold release agent according to claim 1, wherein the organic salt of the unsaturated fatty acid is a monoethanolamine salt, a diethanolamine salt, a triethanolamine salt, or a morpholine salt. 3. The concrete mold release agent according to claim 1, wherein 3 to 10% by weight of an unsaturated fatty acid or an organic salt thereof is blended with respect to the liquid water-repellent substance. 4. A nonionic surfactant having an HLB value of 8 to 8.
The mold release agent for concrete according to any one of claims 1 to 3, which is in the range of 12. 5. The concrete mold release agent according to claim 1, wherein the unsaturated fatty acid is oleic acid.