KR20150049925A - Cement mortar additive for extrusion molding and cement mortar for extrusion molding having the additive - Google Patents

Abstract

The present invention relates to a cement mortar additive for extrusion molding and to cement mortar including the additive for extrusion molding, wherein the additive has a particular particle size distribution and includes surface-coated cellulose ether as a wetting agent. According to the present invention, a surface of cellulose ether is coated with a wetting agent, thereby appropriately adjusting dissolving speed and water retentivity of the cellulose ether. Accordingly, discharge pressure of cement mortar including the same for extrusion molding may be lowered, and discharge speed may be improved. As a result, extrusion productivity of a cement mortar dough may be improved, and hardness and surface smoothness of an extrusion-molded cement product may be improved. Moreover, the particle size of the cellulose ether is adjusted to be a fine powder, thereby further improving discharge pressure.

Description

TECHNICAL FIELD The present invention relates to a cement mortar for extrusion molding and a cement mortar for extrusion molding containing the same,

The present invention relates to a cement mortar additive for extrusion molding comprising a cellulose ether having a specific particle size distribution and surface-coated with a wetting agent, and a cement mortar for extrusion molding comprising the same.

Cement mortars for extrusion include cement, fine aggregates, fibers and additives. Such cement mortar for extrusion molding is generally widely used in civil engineering and construction fields such as building exterior materials, roofing materials, flooring materials and soundproof walls.

Conventionally, asbestos fibers have been used to produce cement extrudates having excellent moldability by optimizing surface smoothness, discharge pressure, and green body hardness. Recently, asbestos has been used as a carcinogen The law became so strict that his use became difficult. Therefore, in order to replace asbestos, inorganic fibers such as glass fiber and carbon fiber; And various fibers such as pulp, waste paper, polyamide fiber, polyester fiber, polypropylene fiber, and organic fiber such as vinylon fiber. Of these, pulp is often used. However, when pulp is used as the fiber, the strength is lowered and the dispersibility as a composition for cement-based extrusion molding is lowered compared with the conventional use of asbestos. Therefore, the discharge pressure is increased or the surface smoothness and moldability of the extrusion- There has been a problem that it is deteriorated.

In order to solve the above problems, cellulose ether is widely used as an additive for cement mortar for extrusion molding.

The cellulose ether is a thickening agent based on a natural material as a basic raw material, exhibits an excellent thickening effect even by adding a small amount of the cellulose ether, and has an excellent water holding power unlike other chemical thickening agents. In addition, cellulose ether is a material suitable for satisfying physical properties such as prevention of segregation of cement mortar as a building thickener, improvement of workability, maintenance of moisture required for cement curing, improvement of adhesion, improvement of shelf stability and improvement of deflection resistance.

Patent Literature 1 (U.S. Patent Application No. 5,047,086) discloses a pulverized pulp fiber; Discloses a cement composition for extrusion molding having excellent moldability and processability by incorporating alkyl cellulose or hydroxyalkyl alkyl cellulose having a viscosity of 80,000 cps or more into cement mortar.

In addition, Patent Document 2 (Japanese Patent Application Laid-Open No. 2009-0080333) discloses that a hydroxyalkyl alkyl cellulose having an alkyl group substitution degree of 1.4 to 1.9 and a hydroxyalkyl group substitution degree of 0.03 to 0.13 is contained to maintain high water retention after extrusion And a green density of the cement mortar is increased to improve the strength of the final cement extrusion molded article.

As described above, cellulose ether is widely used as a construction additive because it can control the flowability that has a significant effect on workability due to high viscosity and water retention.

However, cellulose ethers with high water retentivity tend to inhibit evenly the introduction of water into other inorganic materials during the wet mixing process of the extrusion cement composition. This adversely affects the softness of the whole mortar dough and causes the discharge pressure to rise at the time of extrusion.

US 5047086 B KR 2009-0080333 A

The object of the present invention is to provide a cement mortar additive for extrusion molding comprising a cellulose ether having a specific particle size and surface-coated with a wetting agent.

Another object of the present invention is to provide a cement mortar for extrusion molding which has a low discharge pressure and a high discharge speed by including the above additives, and has improved hardness and surface condition of a molded article.

In order to solve the above-mentioned problems, the present invention is characterized by comprising cellulose ether surface-coated with a wetting agent, wherein 65 to 100% by weight of the cellulose ether has a particle size of more than 0 μm and not more than 107 μm A cement mortar additive for extrusion molding is provided.

The coating amount of the wetting agent is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the cellulose ether.

The wetting agent is preferably an anionic surfactant or a neutral surfactant. The anionic surfactant may be at least one selected from the group consisting of carboxylic acid salts, sulfonic acid salts, sulfuric acid ester salts and phosphoric acid ester salts, The activator may be at least one selected from the group consisting of fatty acid monoglycerin ester, fatty acid polyglycol ester, fatty acid sorbitan ester and fatty acid alkanolamide.

Hydroxypropylmethylcellulose having a degree of methyl group substitution (DS) of 1.4 to 1.9 and a degree of hydroxypropyl group substitution (MS) of 0.03 to 0.33; And hydroxyethyl methylcellulose having a methyl group degree of substitution (DS) of 1.4 to 1.9 and a degree of substitution (MS) of hydroxyethyl group of 0.03 to 0.33, or a mixture thereof, and the viscosity of the cellulose ether is It is preferably 10 to 200,000 cps as measured at 20 캜 and 20 rpm using a Brookfield viscometer based on a 2.0 wt% solution.

The present invention also provides a cement mortar for extrusion molding comprising the additive and a method for producing the same.

According to the present invention, the initial dissolution rate and water retention of the cellulose ether can be appropriately controlled by coating the surface of the cellulose ether with the wetting agent.

As a result, the discharge pressure of the cement mortar for extrusion molding can be lowered and the discharge speed can be improved. As a result, the extrusion productivity of the cement mortar kneaded product can be increased. In addition, the hardness of the extrusion- It is possible to provide a cement mortar for an extrusion molding with improved smoothness.

In addition, the discharge pressure can be further improved by controlling the particle size of the cellulose ether to fine powder.

Brief Description of the Drawings Fig. 1 is a simplified view of the water absorption behavior of a cellulose ether not treated with a wetting agent during wet mixing of a cement mortar composition for extrusion molding.
Fig. 2 is a simplified representation of the water absorption behavior of cellulose ether treated with wetting agent during wet mixing of the cement mortar composition for extrusion molding.

The present invention relates to a cement mortar additive for extrusion molding comprising a cellulose ether surface-coated with a wetting agent, wherein 65 to 100% by weight of the cellulose ether has a particle size of more than 0 탆 and not more than 107 탆 To a cement mortar for extrusion molding. As used herein, the term " cellulose ether " means a cellulose ether or a cellulose ether derivative.

Generally, the cellulose ether together with cement or the like is rapidly dissolved as soon as it is dispersed in water and exhibits water retention, so that the amount of the cellulose ether tends to be excessively concentrated to cellulose ether and not uniformly dispersed in other inorganic materials other than cellulose ether. This negatively affects the softness of the whole cement mortar kneaded product, thereby causing a problem of raising the discharge pressure upon extrusion of the mortar kneaded product.

Therefore, in the present invention, the surface of the cellulose ether having a specific particle size is coated with a wetting agent to appropriately adjust the initial dissolution rate and water retention of the cellulose ether so that the water is uniformly dispersed not only in the cellulose ether but also in other inorganic materials in the mortar, And to reduce the discharge pressure of the cement mortar for extrusion molding so as to be capable of absorbing moisture.

A wetting agent is a surfactant that increases the spreading and penetration properties of a liquid by lowering the surface tension. It is a compound having both a hydrophobic group and a hydrophilic group. In general, the wetting agent is adsorbed on the surface of a solid material which does not easily wet the water, and then the hydrophilic group is arranged outwardly, and as a result, the solid material is wetted with water. In the present invention, And is dissolved earlier than the cellulose ether, thereby delaying the initial dissolution rate of the cellulose ether.

That is, when the cellulose ether surface-coated with the wetting agent is dispersed in water together with an inorganic material such as cement, the wetting agent located on the surface first dissolves in water, and then the dissolution of the cellulose ether starts. While the wetting agent is dissolved, the dispersibility of the cellulose ether in the cement mortar dispersion is increased, and water is evenly dispersed in other inorganic materials such as cement. After the water is uniformly absorbed in the mortar as a whole, that is, after all of the wetting agent is dissolved, the cellulose ether is dissolved and the water retention is developed so that the water retaining property is maintained in a moist state as a whole.

1 and 2, in the case of the cellulose ether (11) in which the wetting agent is not treated during the wet mixing of the cement mortar (1) composition for extrusion molding, the cellulose ether (11 The distance d between the cellulose ether 11 and the inorganic material 13 in which the water 12 has been absorbed becomes close to the amount of water 14 absorbed excessively and the inorganic material 13 in the vicinity of the cellulosic ether 11 ), The moisture 14 is taken by the cellulose ether 11. In addition, the moisture 14 that is not absorbed by the cellulose ether 11 tends to collect around the cellulose ether 11, so that the moisture 14 is not uniformly dispersed throughout the mortar 1. On the other hand, in the case of the cellulose ether treated with the wetting agent according to the present invention, as shown in FIG. 2, since the cellulose ether 11 absorbs only a proper amount of water 12, the inorganic matter 13 in the cement mortar 1, The absorbed cellulose ether 11 is uniformly dispersed at an appropriate distance d and the water 14 is dispersed evenly to the inorganic material 13.

The amount of the wetting agent is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the cellulose ether. When the amount of the wetting agent is less than 0.1 part by weight, dissolution of the cellulose ether occurs rapidly and the water holding capacity is rapidly developed. If the amount exceeds 10 parts by weight, the dissolution of the cellulose ether may be delayed considerably and the cement hydration phenomenon may occur rapidly with the decrease of the maintenance ability. As a result, the drying property of the mortar may deteriorate the workability upon extrusion Which is undesirable.

As the wetting agent, an anionic surfactant or a neutral surfactant may be used. More preferably, the anionic surfactant may be at least one selected from the group consisting of carboxylic acid salts, sulfonic acid salts, sulfuric acid ester salts and phosphoric acid ester salts, The neutral surfactant may be at least one selected from the group consisting of fatty acid monoglycerin esters, fatty acid polyglycol esters, fatty acid sorbitan esters and fatty acid alkanolamides.

In addition, 65 to 100% by weight of the cellulose ether used in the cement mortar additive for extrusion molding of the present invention has a particle size of more than 0 mu m and not more than 107 mu m. By adjusting the particle size of the cellulose ether to fine powder, the effect of improving the discharge pressure can be added. However, when the content of the cellulose ether having the above-mentioned particle size is less than 65% by weight, the dispersibility of the cellulose ether is lowered and the particle size of the cellulose ether sufficiently dispersed in the cement mortar dispersion after the wetting agent coated on the surface of the cellulose ether is dissolved Coarse powder) is excessive, the solubility of the cellulose ether is low, so that the water holding performance is delayed, and at the same time, the mortar supplied to the extruder is dried quickly due to the hydration of the cement, and the discharge pressure rises.

The cellulose ether is hydroxypropylmethylcellulose having a degree of methyl group substitution (DS) of 1.4 to 1.9 and a degree of hydroxypropyl group substitution (MS) of 0.03 to 0.33; And hydroxyethylmethylcellulose having a degree of methyl group substitution (DS) of 1.4 to 1.9 and a degree of substitution (MS) of hydroxyethyl group of 0.03 to 0.33, or a mixture thereof, but is not limited thereto.

Here, the term "degree of substitution" means the average number of hydroxyl groups substituted with an alkyl group per anhydrous glucose unit. When the degree of methyl group substitution is high, the hydrophobicity is high and the degree of substitution of hydroxypropyl group or hydroxyethyl group In the case of a small amount, the hydrophobicity becomes high. For example, when methyl cellulose having a methyl group substitution degree of more than 1.9 and hydroxypropyl methyl cellulose having a hydroxypropyl group substitution degree of less than 0.03 are used together, water retention of the cellulose ether becomes insufficient and workability of the extrusion molding cement mortar This can be bad.

The viscosity of the cellulose ether is preferably 10 to 200,000 cps, more preferably 2,000 to 120,000 cps, when measured at 20 DEG C and 20 rpm using a Brookfield viscometer based on a solution having a concentration of 2.0 wt% Lt; / RTI > If the viscosity of the aqueous solution of the cellulose ether is less than 10 cps, the effect of thickening is not exhibited, and if it exceeds 200,000 cps, the workability becomes very poor due to high viscosity, which is not preferable.

The present invention provides a cement mortar for extrusion molding containing the additive and a method for producing the same.

The method for producing a cement mortar for extrusion molding comprises the steps of: coating a surface of a cellulose ether with a wetting agent; mixing 65 to 100% by weight of the cellulose ether coated with the wetting agent with a particle size of more than 0 탆 and 107 탆 or less Mixing the cement mortar composition containing the coated cellulose ether, cement and an inorganic material; and wet-mixing the cement mortar composition with water.

In the coating step of the wetting agent, the coating method may include a coating method in a wet state after the cellulose ether is synthesized and pulverized and dried, a method of coating in a powder state after pulverization and drying, and the like , The method is not limited. One example of such a method is a method of spraying a liquid wetting agent with a spray while spinning the cellulose ether in a wet state at a high speed.

In the particle size controlling step, a method of blowing a specific intensity of air to the pulverized cellulose ether so as to separate only the cellulose ether particles having a specific particle size range may be used, or a method using a standard having a specific mesh may be used There is no restriction on the method.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these embodiments.

(Manufacture of cement mortar additive for extrusion molding)

Example  One

(HPMC) having a methyl group degree of substitution of 1.45, a degree of substitution of propyl group of 0.24 and a viscosity of 60,400 cps, 0.5 parts by weight of Polyoxyethylene glycol (humectant) and 200 parts by weight Prepare negative water each. The HPMC was sprayed with polyoxyethylene glycol dispersed in water while rotating at 130 rpm using a Hobart Mixer to obtain HPMC coated with a polyoxyethylene glycol dispersion.

The HPMC was dried at 80 ° C for 3 hours, and then pulverized using a crusher (ACM MILL) at a rotating speed of 50 rpm to separate the HPMC powder from the dried HPMC powder through the drying step to obtain HPMC powder coated with a wetting agent.

The thus obtained HPMC powder was classified into the following particle size distribution using ASTM standard, and then classified HPMC powder was mixed with each other to prepare a cement mortar additive for extrusion molding. The viscosity of the hydroxypropylmethylcellulose was measured using a Brookfield viscometer at a concentration of 2.0 wt% at 20 ° C and 20 rpm.

≪ Particle Size Distribution of Cellulose Ether (CE)

- 80mesh (173 mu m) Standard penetration: 90 wt%

- 140mesh (107 mu m) Standard penetration: 65 wt%

- 230mesh (65 mu m) Standard penetration: 40 wt%

The particle size distribution was controlled by sequentially classifying the cellulose ether in the order of 80 mesh (173 占 퐉), 140 mesh (107 占 퐉) and 230 mesh (65 占 퐉).

Example  2 to 4 and Comparative Example  1 to 2

A cement mortar additive for extrusion molding was prepared in the same manner as in Example 1, except that the passage through the 140 mesh standard of the cellulose ether (CE) sample and the throughput of the wetting agent were adjusted as shown in Table 1 below.

CE Type 140mesh standard body passing minutes Wetting agent Example 1 HPMC 65 wt% 0.5 parts by weight Example 2 HPMC 70 wt% 0.5 parts by weight Example 3 HPMC 65 wt% 1.0 part by weight Example 4 HPMC 70 wt% 1.0 part by weight Comparative Example 1 HPMC 65 wt% 0.0 part by weight Comparative Example 2 HPMC 55 wt% 0.5 parts by weight

(Cement mortar for extrusion molding)

50 parts by weight of cement (product of Asia Cement Co., Portland cement), 45 parts by weight of silica sand and 5 parts by weight of pulp fiber were mixed to prepare a cement mortar composition for extrusion molding without addition of cellulose ether. Then, 0.7 parts by weight of the additive prepared in Example 1 was added to 100 parts by weight of the cement mortar composition. 27 parts by weight of water was added to 100 parts by weight of the cement mortar composition and kneaded to prepare a cement mortar for extrusion molding. Subsequently, the extruded cement mortar was extruded by an extruder (50pi vacuum extruder, ISHIKAWA TOKI) to produce an extrudate. At the time of extrusion of the cement mortar, the input water to the extruder and the temperature of the effluent therefrom were 30 ° C and 30 ° C, respectively.

Cement mortar containing the additives prepared in Examples 2 to 4 and Comparative Examples 1 and 2 were also prepared according to the above-mentioned method for producing a cement mortar for extrusion molding.

The performance of each cement mortar containing the cement mortar additive for extrusion molding prepared in the above Examples and Comparative Examples was evaluated as follows, and the results are shown in Table 2 below.

(1) Discharge pressure

During the extrusion of cement mortar, the pressure of the pressure gauge installed in the vacuum extrusion molding machine was visually observed to evaluate the discharge pressure. When the value was expressed by the 10-point method, the discharge pressure was lowered, which means that the extrusion productivity was improved.

(2) Discharge speed

In the extrusion molding of cement mortar, the discharge speed was evaluated by measuring the time from the start of the extrusion molding panel emerging through the discharge port to the time when it became 30 cm, and converting it into a speed value. The faster the discharge speed, the more excellent the extrusion productivity becomes.

(3) Hardness of the molding

The hardness of the extruded extruded parts during extrusion molding of cement mortar was evaluated using a Texture Analyzer (LLOYD, TA PLUS). The larger the numerical value is, the lower the hardness and the more conservative and lubricious .

(4) Surface state

The surface state of the extrudate was evaluated by visually observing the extrudate coming out from the die during the extrusion molding of the cement mortar for extrusion molding and when the value was expressed by the 10-point method, it means that the surface state was smooth .

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Discharge pressure 8 8 7 7 6 6 Discharge speed 8 8 6 7 5 6 Hardness 8 9 6 6 5 5 Surface condition 9 9 7 8 6 6

With reference to Table 2, in the case of the cement mortar containing the cement mortar additive for extrusion molding prepared according to Examples 1 to 4 of the present invention, Comparative Example 1 in which the wetting agent was not added and Cellulose It can be seen that the extrusion productivity is excellent because the ejection speed is equal to or higher than that of the cement mortar comprising the additive composition prepared in Comparative Example 2 containing 55 wt% of ether and the ejection pressure is low and the hardness of the molded product is low, It can be indirectly known that the mortar has excellent water retention and lubricity, and the surface state is also smooth.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments but is to be construed as being limited only by the appended claims. Should be construed as being included in the scope of the present invention.

1: Cement mortar composition for extrusion molding
11: Cellulose ether
12: Water absorbed in cellulose ether
13: Inorganic material
14: Moisture dispersed in the mortar composition

Claims (6)

A cellulose ether surface-coated with a wetting agent,
Wherein 65 to 100% by weight of the cellulose ether has a particle size of more than 0 占 퐉 and not more than 107 占 퐉. The method according to claim 1,
Wherein the coating amount of the wetting agent is 0.1 to 10 parts by weight based on 100 parts by weight of the cellulose ether. The method according to claim 1,
Wherein the wetting agent comprises at least one anionic surfactant selected from the group consisting of carboxylic acid salts, sulfonic acid salts, sulfuric acid ester salts and phosphoric acid ester salts; At least one neutral surfactant selected from the group consisting of fatty acid monoglycerin esters, fatty acid polyglycol esters, fatty acid sorbitan esters and fatty acid alkanolamides; Wherein the cement mortar additive is a cement mortar additive for extrusion molding. The method according to claim 1,
Hydroxypropylmethylcellulose having a degree of methyl group substitution (DS) of 1.4 to 1.9 and a degree of hydroxypropyl group substitution (MS) of 0.03 to 0.33; And hydroxyethylmethyl cellulose having a degree of methyl group substitution (DS) of 1.4 to 1.9 and a degree of substitution (MS) of hydroxyethyl group of 0.03 to 0.33, or a mixture thereof, characterized in that the cement mortar additive . The method according to claim 1,
Wherein the viscosity of the cellulose ether is from 10 to 200,000 cps as measured at 20 캜 and 20 rpm using a Brookfield viscometer based on a 2.0 wt% solution. A cement mortar for extrusion molding comprising the additive according to any one of claims 1 to 5.

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