JP3140565B2 - Cement adhesion inhibitor and method for preventing adhesion to metal surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agent for preventing cement from adhering to a metal surface and a method for preventing the adhering of cement. Kneading mixers, discharge chutes, conveyors, agitator drums of truck mixer trucks, etc. used in ready-mixed concrete manufacturing plants and concrete product manufacturing plants, etc., as well as formwork and various test equipment used for quality control of mortar and concrete, Cleaning and cleaning require time and effort because cement paste and mortar adhere to the metal surface in contact with the hydraulic cement material.

[0002]

2. Description of the Related Art Conventionally, among the above-mentioned locations, the inside of an agitator drum of a truck mixer, the inside of a kneading mixer, a discharge chute, etc., are constantly stirred for a concrete material, or a metal surface at a location where the concrete material flows. Generally does not take measures to prevent the cement material from adhering.

On the other metal surface, a portion in contact with the hydraulic cement material is covered with a material having elasticity and abrasion resistance, such as rubber or Teflon resin, which is formed into a sheet or mat. Thereby, adhesion of cement paste and mortar is prevented. Furthermore,
When a hydraulic cement material is mainly formed by a mold, an oil mainly composed of mineral oil is generally applied to the surface of the mold as a release agent.

[0004]

However, if the above-mentioned countermeasures are not taken, the parts relatively unrelated to the material flow, such as the back side of the stirrer of the kneading mixer and the vicinity of the upper opening of the chute, are used. Since the paste and mortar that have been scattered and accumulated gradually adhere and solidify, eventually reducing the performance of the apparatus, a cleaning operation is required, and this operation has led to a decrease in operation efficiency. .

In the method of coating a metal surface, it is possible to prevent the paste or mortar from adhering for a certain period of time, but basically, it is not possible to prevent the adhesion itself. Since the life of the material is relatively short, it is not always satisfactory in view of the replacement cost and labor in case of breakage. Furthermore, in the method of applying a release material, the metal surface forming the mold is more hydrophilic than lipophilic and can withstand only one use, so that the method for preventing adhesion is incomplete in some cases. Many.

[0006] For this reason, there is a problem that the operation cost is increased because much time and labor is required for removing and cleaning the cement paste and the mortar material adhered thereto. Therefore, the present invention provides an agent for preventing cement adhesion to a metal surface and a method for preventing adhesion of the cement paste and mortar to a metal surface, which can reduce the amount of adhesion of the mortar to the metal surface and can easily remove even if it adheres. The purpose is to:

[0007] The anti-adhesion agent and the anti-adhesion method are to delay the cement hydration and hardening reaction to such an extent that it can be easily washed away with a small amount of water within about 24 hours. Strong adhesion to surfaces, especially iron surfaces, during concrete mixing or
It is necessary that the surface of the mortar / concrete material can be firmly coated even if a continuous rubbing impact due to stirring flow of the mortar / concrete material immediately after kneading is applied.

[0008]

In order to solve the above-mentioned problems, various materials were tested for their ability to prevent adhesion to metal surfaces. As a result, polyhydroxycarboxylic acid ester was found to have an excellent effect of preventing cement from adhering to metal surfaces. It was found to be effective. In addition, they have found that tannic acid as a polyhydroxycarboxylic acid ester exhibits an excellent effect of preventing cement from adhering to a metal surface.

[0009] Other polyhydroxycarboxylic acid esters include corirazine, kevrazic acid and ascorbic acid. Furthermore, as a method of using these, it is effective to apply these cement adhesion preventing agents to the metal surface to prevent cement adhesion. In addition, it has been found that the applied cement can be easily removed by applying a cement adhesion inhibitor to the attached cement.

[0010]

[Function] Polyhydroxycarboxylic acid ester forms a complex or chelate compound with calcium ions on the surface of cement particles to form a protective film of retarder by uniformly adsorbing on the surface, and strongly affects the setting of cement. It is considered that when hydrating the constituent mineral C3S, this protective film physically inhibits the contact between the cement particles and water and delays the hydration reaction. This protective film is destroyed over time by the osmotic pressure of water and the expansion pressure of the hydrated product crystals generated by the hydration reaction that progresses slightly inside, and thereafter the hydration reaction is gradually accelerated and condensed. It is presumed to lead.

Further, tannic acid is known as a rust preventive, and reacts quickly with iron to form iron tannin. Iron tannin is a stable compound having a black color. When a solution containing tannic acid is applied to an iron device, a strong black film is formed. This coating is so strong that it is not easily destroyed by a considerable abrasion shock. Furthermore, tannic acid is decomposed into strong retarding components such as gallic acid and pyrogallol by the alkalinity of the cement hydration reaction system, and the cement hydration reaction system that has come into contact with the formed black film is greatly delayed, for at least 24 hours or more. Does not cure. Therefore, the daily cleaning work on the metal surface of the apparatus that has performed this processing is greatly labor-saving, and as a result, the operation efficiency is improved.

[0012] Further, by directly spraying and atomizing not only on the metal surface of the apparatus but also on the cement paste or mortar adhered thereto, the curing can be delayed and the cleaning operation can be saved. A higher effect can be obtained by using this treatment in combination with application to a metal surface.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a cement adhesion preventing agent and a method for preventing adhesion to a metal surface according to the present invention will be described below. An aqueous solution containing tannic acid was sprayed on the upper metal portion of the completely cleaned discharge chute before the operation of the ready-mixed concrete batcher plant was started. Approximately 5 minutes later, when the mist was slightly dried and the surface turned black, operations began at 8:30 am. Two hours later, at 10:30 in the morning, the mortar film was sprayed and adhered to the mortar film.
The operation in the morning was stopped at 0:10 pm, and the operation was left as it was without performing the cleaning work which is usually performed before noon. The operation started in the afternoon at 1:15 pm, and 3 hours later at 3 pm
The mortar film scattered at 15:00 was again sprayed and atomized. After the operation on the test day, cleaning work was started at 6:20 pm, and the amount of labor, required time, and used water amount of the cleaning work were measured.

The anti-adhesion agent used here is prepared by dissolving a commercially available reagent tannic acid powder in water and dissolving a tannic acid solution at a concentration of 5%, 10% or less.
% And 20% aqueous solution (weight percent), the amount of mist was 200 cc per square meter per time, and the measurement was also performed using a sodium gluconate aqueous solution conventionally known as a retarder as a comparative example. went.

Table 1 shows the results together with the measurement results of the conventional example. According to this, both the time required for cleaning and the amount of water required for cleaning are extremely small as compared with the conventional example and the comparative example.

[0016]

[Table 1] In the above embodiment, the case where only an aqueous solution of tannic acid is used has been described as an example. However, known cement dispersants such as polyacrylate, hydroxycarboxylic acid such as alginic acid, ligninsulfonic acid and derivatives thereof, and polyol A derivative, a polyoxyethylene alkyl allyl ether derivative, a formalin condensate of an alkyl allyl sulfonate, a formalin condensate of a melamine sulfonate, or a polycarboxylic acid-based polymer compound may be used in combination to increase the viscosity of the solution. . By all means, the liquid can be efficiently adhered to the metal surface whether it is a vertical surface or a rear surface, and the effect of preventing adhesion can be improved.

Further, other conventional retarders such as organic retarders such as salts of hydroxycarboxylic acids such as gluconic acid or glucoheptonic acid and keto acids, sugars, alcohols, and inorganic retarders. The properties of the diluent may be changed by using a certain silicofluoride, phosphate, or boric acid in combination.

[0018]

As described above, according to the present invention, a solution containing a polyhydroxycarboxylic acid ester is employed as an antiadhesive agent, and the solution is applied to a metal surface or simply atomized on the adhered cement. Thus, it is possible to greatly reduce the labor required for cleaning the manufacturing apparatus, improve the operation efficiency, and reduce the manufacturing cost.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Inogawa 583 Tomimachi, Funabashi-shi, Chiba Sumitomo Cement Co., Ltd. Central Research Laboratory (56) References JP-A-63-117941 (JP, A) JP-A-2 JP-A-247387 (JP, A) JP-A-63-78966 (JP, A) JP-A-1-1411861 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09K 3/00 B01F 15/00 CAPLUS (STN)

Claims (4)

(57) [Claims] 1. An agent for preventing cement from adhering to a metal surface, comprising a polyhydroxycarboxylic acid ester. 2. The method according to claim 1, wherein the polyhydroxycarboxylic acid ester is tannic acid. 3. A method for preventing cement adhesion to a metal surface, comprising applying the cement adhesion inhibitor according to claim 1 or 2 to a metal surface. 4. A method for preventing cement from adhering to a metal surface, comprising applying the cement adhering agent according to claim 1 to the adhered cement.