JP2020131464A - Concrete formwork release agent - Google Patents

Abstract

To provide a concrete formwork release agent which can improve not only releasability from the formwork and looking of the concrete products after form removal and the emulsion stability when diluted and mixed with water, but also operability by reducing formwork cleaning labor due to adhesion of formwork slags after form removal, which is a drawback of conventional emulsion type release agents using vegetable oil as base oil.SOLUTION: A concrete formwork release agent includes fatty acid polyoxyethylene glycerol ester having (A)animal and vegetable oil and (B)alkyl groups of straight chains/branched-chains of carbon numbers C8-C22.SELECTED DRAWING: None

Description

The present invention relates to a concrete formwork release agent. In particular, the present invention relates to a concrete formwork release agent which is excellent not only in formwork releasability of a concrete molded product but also in suppressing adhesion of cement residue to the formwork and in easiness of cleaning the formwork.

Conventionally, when manufacturing concrete products, concrete is poured into a mold made of steel, ceramic, synthetic resin, etc., compacted by vibration or the like, and released from the mold after steam, watering, or compress curing. At this time, in general, a release agent is applied to the formwork in advance so that the concrete and the formwork do not stick to each other, thereby facilitating the release from the formwork.

Concrete formwork release agents are based on mineral oils and animal and vegetable oils, and are roughly classified into oil-based types and aqueous (emulsion) types.

Generally, the oil-based type is used by mixing wax, resin, fatty acid, metal soap, surfactant, and rust preventive as additives in lubricating oil such as machine oil and turbine oil, and diluting with undiluted solution or kerosene, light oil, etc. ..

On the other hand, the emulsion type is used by diluting and mixing a release agent with water to make a milky lotion and applying or spraying it on a mold.

As a formwork peeling mechanism, alkaline ions in concrete react with organic acids in a stripping agent to form a water-soluble fatty acid soap. Furthermore, the presence of calcium ions in concrete produces metal soaps such as sparingly soluble calcium soaps. This metal soap forms a mold release layer between the concrete and the formwork, a chemical adsorption type that exerts a mold release effect, a physical type release agent that adsorbs to the mold and forms a barrier that does not adhere concrete, and a lubricating oil film on the surface. There are lubrication type release agents that make and lubricate and release the mold, and there are also release agents that have the action of combining these.

Fatty acids containing or blended with animal and vegetable oils as the main component react with the alkali content of cement to form water-soluble fatty acid soaps. Then, the poorly soluble calcium soap reacts with the calcium content contained in the cement to exert a peeling effect.

Oil-based formwork release agents generally tend to leave oil stains and pinholes on concrete moldings, but they also have excellent mold release force, and there is little adhesion of cement residue (glue) to the formwork after demolding. It has the feature that it is easy to clean.

Patent Document 1 discloses a concrete mold release agent composed of a mineral oil-based solvent containing a phospholipid and a sorbitan ester or an ethylene oxide adduct thereof as an oil-based mold release agent. The formwork release agent described in Patent Document 1 is a mold release agent that exhibits excellent mold release property, smoothness of concrete surface, and rust preventive effect. However, since it is based on a mineral solvent, there are concerns about the effects of environmental pollution and exposure to workers.

Patent Document 2 discloses a release oil containing animal fats and oils and / or vegetable fats and oils and nonionic surfactants of polyoxyethylene sorbit fatty acid esters as emulsion-type mold release agents. .. The mold release agent described in Patent Document 2 is a concrete release agent having excellent mold releasability, emulsion stability, and reduction of environmental pollution. However, there is no mention of the releasability of concrete when continuously placed in the same formwork, the adhesion of slag to the formwork, and the cleanability of the formwork.

Japanese Patent No. 2938629 Japanese Patent No. 4205585

Mineral oil contains organic volatile components (VOCs) and components that are harmful to the human body, so there are concerns about exposure to workers, health hazards due to odors, environmental pollution due to leakage to soil, and high flammability and safety such as fires. Has been done.

Therefore, in recent years, concrete formwork release agents that take into consideration the reduction of workers and environmental pollution have been put on the market and are becoming widespread.

Some of these release agents are based on animal and vegetable oils and fatty acid esters, and because they do not contain harmful components such as VOCs and have low flammability, they have little impact on work safety and the human body, and occupational safety and health. It has also been attracting attention in terms of risk assessment.
Then, a surfactant, a rust preventive, or the like may be blended as an additive, and it is usually used in an emulsion state after being diluted and mixed with water or diluted in advance.

Compared to oil-based release agents based on mineral oil, these are often superior in aesthetics (less oil stains, bubbles, and pinholes) of concrete moldings, but they do not cause soap to adhere to the formwork after demolding. There is a drawback that the mold is easily soiled by the generated metal soap and requires labor for cleaning. When repeatedly placing concrete, the formwork had to be cleaned in advance with a scraper, a sander, etc., and it was difficult to remove the formwork from the formwork, so that workability was greatly impaired.

An object of the present invention is to use conventional vegetable oil as a base oil as well as releasability from a mold, aesthetic appearance of a concrete product after demolding, and emulsion stability when diluted and mixed with water in order to solve the above problems. It is an object of the present invention to provide a concrete formwork release agent which reduces the labor of cleaning the formwork due to the adhesion of the formwork after demolding, which is a drawback of the emulsion type release agent, and improves the workability.

Therefore, as a result of diligent studies in view of the above problems, the present inventors have obtained a finding to improve the above problems by blending animal and vegetable oils with polyoxyethylene glyceryl which is a fatty acid having a specific alkyl chain.
That is, the present invention is a formwork release agent for concrete, which contains animal and vegetable oil and a nonionic surfactant of fatty acid polyoxyethylene glyceryl having a linear / branched alkyl group having C8 to C22 carbon atoms. is there.

The present invention includes the following aspects.

Item 1. A formwork remover for concrete containing (A) animal and vegetable oil and (B) fatty acid polyoxyethylene glycerin esters having a linear / branched alkyl group having C8 to C22 carbon atoms.

Item 2. The concrete formwork release agent according to Item 1, wherein the HLB value or mixed HLB value of Item 2 (B) is in the range of 7 to 13.

Item 3. The formwork release agent for concrete according to Item 1 or 2, which contains 1 to 20% of the above (B) in the formwork release agent.

Item 4. The concrete formwork release agent according to any one of Items 1 to 3, which is used by diluting and mixing the concrete formwork release agent with water.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a concrete formwork release agent which has good mold releasability, less adhesion of concrete residue to the formwork after demolding, and can save time and labor required for cleaning the formwork. According to the concrete formwork release agent of the present invention, it is expected that concrete products can be efficiently manufactured.

Specifically, the concrete formwork release agent according to the present invention for achieving the above object is as follows.

The concrete formwork release agent of the present invention contains (A) animal and vegetable oils and (B) fatty acid polyoxyethylene glycerin esters having linear / branched alkyl groups having C8 to C22 carbon atoms.

(A) Animal and vegetable oils Animal and vegetable oils are oils and fats derived from animals and / or plants. Animal and vegetable oils preferably have a flash point of 250 ° C. or higher at 1 atm. The animal and vegetable oils used include, for example, rice oil, rapeseed oil, corn oil, soybean oil, sesame oil, olive oil, palm oil, castor oil, palm oil, palm kernel oil, flaxseed oil, cottonseed oil, peanut oil, and tung oil. , Animal oils such as beef fat, pork fat, fish oil, etc., preferably rice oil, rapeseed oil, corn oil, soybean oil, sesame oil, olive oil, castor oil, palm oil, cottonseed oil, peanut oil, tung oil and other vegetable oils, beef fat. , Pork fat, animal oil such as fish oil, etc.

The animal and vegetable oils of the present invention can be used alone or in admixture of two or more.

As the animal and vegetable oil, refined oil or crude oil can be used. Animal and vegetable oils should be liquefied at room temperature so that they do not solidify during production or storage.

The animal and vegetable oil can be about 80 to 99% by mass in the total mass of the concrete formwork release agent of the present invention.

(B) Fatty acid polyoxyethylene glycerin esters (fatty acid polyoxyethylene glyceryls, nonionic surfactant)
The fatty acid polyoxyethylene glycerin esters (fatty acid polyoxyethylene glyceryls) of the present invention have an average of about 3 to 60 polyethylene glycols (total number of moles of ethylene oxide added) of 1 to 3 (preferably 3) on the hydroxyl groups of glycerin. (Preferably about 3 to 20) are ether-bonded, and 1-3 hydroxyl groups that are not ether-bonded to polyethylene glycol and / or polyethylene glycol and carbon atoms C8 to C22 (preferably C10 to C20, more preferably C12 to C12 to). It has a structure in which an ester bond is formed with a fatty acid having a linear / branched alkyl group of C18). Fatty acid polyoxyethylene glycerin esters are known to act as nonionic surfactants.

The fatty acid having an alkyl group having C8 to C22 carbon atoms may be either a straight chain or a branched chain. Fatty acids having branched chains are particularly preferable. Isostearic acid is particularly preferable from the viewpoint of economy and availability.

As an example of fatty acid polyoxyethylene glycerin esters, capric acid / capric acid polyoxyethylene (average ethylene oxide (hereinafter abbreviated as EO) 4 to 8) glycerin esters, (mono, di, tri) Polyoxyethylene oleate (average number of moles with EO added 5 to 30) glycerin esters, (mono, di, tri) Polyoxyethylene stearate (average number of moles with EO added 5 to 30) glycerin esters, (mono, di, tri, Tri) Polyoxyethylene isostearate (average number of moles of ethylene oxide added 3 to 60) glycerin esters and the like can be mentioned.

From the viewpoint of emulsion stability, solubility in base oil, and defoaming property of bubbles generated during concrete placement, the HLB value (Hydrophyllic-Lipopicular Balance) of the surfactant when it is used alone or when it is mixed is 7 to 13. Is more preferable.

The HLB value is a value indicating the degree of affinity of the surfactant between water and oil, and can be determined by the Griffin method.

Further, the HLB value when the surfactant is mixed can be obtained by the weighted average of the HLB values of each surfactant component.

The nonionic surfactants of the fatty acid polyoxyethylene glycerin esters having a linear / branched alkyl group having C8 to C22 carbon atoms (B) blended in the present invention may be used alone or in combination of two or more.

The blending ratio of the fatty acid polyoxyethylene glycerin esters is not limited as long as it is dissolved in a release agent and an emulsified state can be obtained when diluted and mixed with water. The blending ratio of the fatty acid polyoxyethylene glycerin ester in the concrete mold release agent of the present invention can be about 1 to 20% by mass, preferably 3 to 15% by mass in the total mass.

(C) Additives The concrete formwork release agent of the present invention may further contain commonly used additives.

Optional components include rust inhibitors, antioxidants, defoamers, preservatives, viscosity index improvers, pour point lowering agents and the like. These are about 5% by mass or less in the total mass in the concrete formwork release agent of the present invention.

The concrete formwork release agent of the present invention is diluted with water such as tap water, mixed well, and used in the form of a milky lotion. When diluted with water, the dilution concentration is, for example, 1 to 30 times, more preferably 5 to 10 times.

The method of applying the concrete formwork release agent of the present invention to the formwork is not limited to any method of spray spraying or mop coating. Further, if the spraying amount or the coating amount is large, discoloration or color unevenness of the concrete product may occur, or if it is small, the effect may not be sufficiently obtained. Therefore, the diluent is preferably about 10 to 50 mL / m ² .

The concrete mold release agent of the present invention is various cements such as Portland cement, blast furnace cement, fly ash cement, silica cement and eco-cement. The admixture (material) can also be used for concrete containing AE water reducing agent, rust preventive, fly ash, silica fume and the like.

Hereinafter, the present invention will be described with reference to Examples. The scope of the present invention is not limited to these examples.

The release agents used in the examples are the release agent of the present invention (Examples 1 to 3) and the comparative release agent (Comparative Examples 1 to 4).

Examples 1-3
Animal and vegetable oils and fatty acid polyoxyethylene glyceryls (nonionic surfactants) were mixed according to the formulations shown in Table 1 below to produce a concrete formwork release agent.

Comparative Examples 1-3
A concrete formwork release agent of Comparative Example was produced by the formulation shown in Table 2 below.

Comparative Example 4
As Comparative Example 4, a commercially available soybean oil-based concrete formwork release agent (which does not belong to the scope of the present invention) was used.

Except for Comparative Example 1, the methods for producing the release agent used in Examples and Comparative Examples were such that each raw material was heated to 60 ° C. and mixed and dissolved with good stirring to obtain a release agent composition.

Evaluation Method The release agents of Examples 1 to 3 and Comparative Examples 2 to 4 are diluted and mixed with water in a steel mold having a length of 10 cm, a width of 10 cm and a length of 60 cm, and 5 mL of the release agent in an emulsion state is applied to the steel mold in Table 3 below. Concrete with the materials and formulations shown in (1) was placed. Comparative Example 1 was the same as in Examples 1 to 3 and Comparative Examples 1 to 3 except that it was applied as a stock solution.

At the time of casting, compaction was performed with a table type vibrator 3000 vpm. After casting, steam curing was performed, and 24 hours later, the state of the demolded concrete and the formwork was observed. These casting tests were repeated 4 times for each release agent.

Evaluation Samples Samples 1 to 3 and Comparative Examples 1 to 4 were used. In the evaluation, except for Comparative Example 1, each of Examples 1 to 3 and Comparative Examples 2 to 4 was diluted 5-fold with tap water, sufficiently mixed and stirred, and used and evaluated in a milky state. In Comparative Example 1, a stock solution was used.
Evaluation of release agent sample The following evaluation items were evaluated according to the contents and evaluation criteria shown below.

(1) Emulsification stability test The release agent sample was diluted 5-fold with tap water, homogenized with a homogenizer at 10,000 rpm for 1 minute, left for 12 hours, and the emulsified state was visually observed.
◯: The emulsified state is maintained and separation is not observed.
Δ: Slightly separated.
×: Separation.

(2) Concrete releasability Demolding condition when pulling up with a crane.
◯: Easily demolded in 4 tests.
Δ: Those that were slightly stuck to the mold even once in four tests and were somewhat difficult to remove from the mold.
X: Those that were stuck to the mold even once in four tests and were difficult to remove from the mold.

(3) Aesthetic appearance The appearance of the concrete product was visually evaluated after demolding.
◯: The surface of the specimen after demolding is smooth and there are few cracks and pinholes (30 mmφ or more and less than 10 per same side surface).
Δ: The surface of the specimen after demolding is smooth and there are few cracks and pinholes (30 mm φ10 or more and less than 50 per same side surface).
X: The surface of the specimen after demolding has many cracks and pinholes (30 mm φ50 or more per same side surface).

(4) Adhesion of slag on the mold surface after demolding and cleanability of the mold ◎: There is almost no slag adhering to the mold after demolding in all four tests, and it is necessary to clean the mold. Non-sexual or easy to remove.
◯: After demolding, thin slag adhered to each surface of the mold at least once in 4 tests, and it was easy to remove.
Δ: A slag adhered thinly on one surface of the mold after demolding at least once in four tests, and it took a lot of labor to remove it.
X: After demolding, the slag adhered to the entire surface of the mold every test, and it took a lot of effort to remove it.

The results are shown in Table 4 below.

It is clear that the concrete formwork release agent of the present invention has good emulsification stability and releasability, and has less adhesion of concrete residue to the formwork after repeated casting and demolding. By using the concrete formwork release agent of the present invention, it is expected that the time and labor required for cleaning the formwork can be omitted and the concrete product can be efficiently manufactured.

Claims (4)

A formwork release agent for concrete containing (A) animal and vegetable oil and (B) fatty acid polyoxyethylene glycerin esters having a linear / branched alkyl group having C8 to C22 carbon atoms. The concrete formwork release agent according to claim 1, wherein the HLB value or the mixed HLB value of the nonionic surfactant is in the range of 7 to 13. The concrete formwork release agent according to claim 1 or 2, which contains 1 to 20% of the nonionic surfactant in the formwork release agent. The concrete formwork release agent according to any one of claims 1 to 3, wherein the concrete formwork release agent is diluted and mixed with water for use.