JPH06135754A - Non-asbestos cement-based extrusion molding composition - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention is a non-asbestos-cement-based extrusion molding composition capable of shortening the curing time after molding and enabling extrusion molding at high temperature with high productivity. I will provide a. [Composition] This composition for extrusion molding was prepared by adding 0.7 to 3% by weight of hydroxyethyl cellulose to a mixture of non-asbestos fiber and cement binder, and the degree of substitution of hydroxyethyl groups was 45% or more and 2% aqueous solution. A cement paste consisting of 100 parts by weight of ordinary Portland cement and 100 parts by weight of water with a viscosity of 15,000 cp or more at 20 ° C is JIS R-
Intermediate value A between the initial values of cement setting and final setting measured by the method of 5201, and the intermediate value between the initial values of setting and setting of cement measured by the same method as above but with 0.2 part by weight of hydroxyethyl cellulose added Hydroxyethyl cellulose having a setting delay time of 70 minutes or less, which is represented by the difference from B, is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-asbestos cement-based extrusion molding composition which provides a cement board reinforced with non-asbestos fibers, which is useful as a building exterior material, roofing material, floor material, etc. Is.

[0002]

2. Description of the Related Art Conventionally, as an exterior material, roof material, floor material, etc. for buildings, cement is mixed with about 10% by weight of asbestos fiber, aggregate, etc., and then water is added and kneaded. Cement boards reinforced with asbestos fibers, which are obtained by extrusion using a shaped die, have been widely used. Asbestos fibers have extremely good dispersibility during kneading, and the obtained kneaded product has good shape retention during extrusion molding and excellent water retention. Furthermore, even when it is cured with a steam pressure cooker at a high temperature of 170 ° C or higher to give dimensional stability and required strength to the extruded product, the heat resistance of asbestos fiber sufficiently withstands the performance as a strength reinforcing fiber. Has been fully demonstrated. However, in recent years, asbestos fibers have a problem of carcinogenicity, which is said to be caused by their unique fiber shape. Therefore, asbestos is not used at all in the above extrusion-molded products, or the addition amount thereof is minimized. Has been requested.

As the fibers to replace asbestos, inorganic fibers such as wollastonite, glass fiber, carbon fiber and sepiolite have been studied, and as organic fibers, vinylon fiber, polypropylene fiber, pulp fiber and aramid fiber have been studied. . However, all of these non-asbestos fibers have poor dispersibility, shape-retaining property, and water-retaining property, and among the organic fibers, there are some fibers that have poor heat resistance and cannot be cured by the steam pressure. In addition, from the viewpoint of cost, those having high reinforcing strength are considerably more expensive than asbestos fibers. Among them, pulp fiber is relatively low in cost and superior in dispersibility to asbestos as compared with other fibers, and further, in an extruded product obtained by adding this in a fixed amount, It is possible to perform nailing, sawing, and the like, which are difficult for the asbestos fiber-containing cement molded product, and it is possible to provide an advantage that the building can be easily attached as an exterior material. For this reason, it has recently attracted attention as an alternative fiber to asbestos.

On the other hand, in extrusion molding of a cement mortar composition, a large amount of pressure is generally applied during molding, and even in the case of a cement composition containing asbestos fibers or pulp fibers,
Water cannot be uniformly retained in the molded body only by the water retention performance of these fibers, and the water is separated and the molded products are bound to each other until the extrusion molded body is set and hardened. It was difficult to maintain the molded body discharged from the die in this state. A method of using an organic binder in a composition for extrusion molding to improve this moldability is proposed, for example, as a organic binder of a cement-based extrusion molded article containing asbestos in Japanese Patent Publication No. 43-7134. In addition to methyl cellulose, hydroxypropyl methyl cellulose, etc., there are hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, polyethylene oxide, sodium polyacrylate, casein, etc. Among them, hydroxyalkyl alkyl cellulose has good dispersibility for cement, aggregates, etc. It is described that it has excellent adhesiveness.

Several proposals have been made for non-asbestos cement-based extrusion molding compositions containing such a binder, for example, Japanese Patent Publication No. 63-12.
Japanese Patent Publication No. 76 discloses that a cemented composition containing pulp fiber, a primary foamed spherical resin, and a binder such as methylcellulose is extruded to obtain a molding capable of sawing and nailing. . However, since the non-asbestos fibers have poor dispersibility and lubricity as described above, when the extrusion molding composition is actually mixed and kneaded to be extruded, heat generation becomes intense. Moreover, the hydroxyalkylalkyl cellulose that is generally used as a binder has the property that it is difficult to dissolve at high temperatures, and even if it once dissolves, it will gel again at the high temperature and impair the fluidity. In order to apply to extrusion molding, it was impossible to mold at all unless the molding process was sufficiently cooled. Attempts were also made to cut the non-asbestos fiber used to cut it into smaller pieces,
When the fiber length is shortened, the shape-retaining property immediately after molding deteriorates, and not only the amount of binder added increases but also the impact resistance of the living body deteriorates.

[0006]

In order to solve these problems, it dissolves even at high temperature and does not gel even after the dissolution.
It was considered to use hydroxyethyl cellulose, which has a relatively high water retention property, but this has the drawback that when extruded at high temperature, the viscosity decreases and cracks occur in the molded product immediately after molding. However, if the amount of addition is increased and extrusion molding is performed, the hardening delay time of the cement becomes longer as the amount increases, so it takes time to perform low-temperature primary curing at around 45 to 70 ° C before steam curing after molding, which increases productivity. Was significantly reduced. On the other hand, it is conceivable that the degree of substitution of the hydroxyethyl group will be extremely reduced and the solubility will be reduced, so that the cement will be extruded in a way that does not prolong the delay time of the effect. However, there was a problem that the extrudability at high temperature was poor. Therefore, an object of the present invention is to provide a non-asbestos-cement-based extrusion molding composition capable of performing extrusion molding at high temperature with ease and high productivity without increasing the curing time after molding. .

[0007]

As a result of studying the above-mentioned problems, the inventors of the present invention have found that the retardation of curing of an extruded product is related to the cement setting retardation performance of a water-soluble cellulose ether such as hydroxyethyl cellulose to be added. It was found that the use of hydroxyethyl cellulose having a short setting delay time allows easy molding even when extrusion molding is performed at a high temperature, and primary curing after molding is sufficiently achieved in a short period of time. And completed the present invention.
That is, the non-asbestos-cement-based extrusion molding composition according to the present invention is prepared by adding 0.7 to 3% by weight of hydroxyethyl cellulose as a binder to a mixture of non-asbestos fiber and cement binder. As ethyl cellulose, a cement paste having a substitution degree of hydroxyethyl groups of 45% or more and a 2% aqueous solution having a viscosity of 20 000 cp or more at 20 ° C. and comprising 100 parts by weight of ordinary Portland cement and 100 parts by weight of water JIS R -The intermediate value A between the initial setting and final setting of cement measured by the method of 5201, and the initial setting and final setting of cement measured by the same method as above for the cement paste to which 0.2 part by weight of hydroxyethyl cellulose was added The setting delay time represented by the difference from the intermediate value B of It is characterized by being used.

Explaining this, as a general method for measuring the setting time of cement, there is described in JIS R-5201, the degree of penetration of the cement depending on the degree of penetration of the needle when the test needle is penetrated into the cement paste. A method of measuring the setting start time and the setting time is known. Regarding the cement setting delay time due to cellulose ether, cellulose ether was added to the cement paste to measure the start and end times of the setting of cement, and the setting start time and end time of the cement paste without addition of cellulose ether were measured. It can be measured by looking at the difference between. However, JIS R-
It is complicated and difficult to understand the comparative study of the two cement setting retarding performances obtained from the two measured values of the initial setting and the final setting of setting by 5201. Therefore, in the setting delay time of the cellulose ether in the present invention, for the cement paste consisting of 100 parts by weight of ordinary Portland cement and 100 parts by weight of water, between the initial setting value and the final setting value of the setting of the cement measured by the method of JIS R-5201. Defined by the value A and the difference between the initial value of the setting of cement and the intermediate value B of the final measured values of cement, measured by the same method as above, with 0.2 parts by weight of cellulose ether added to the cement paste. did.

When cellulose ether having a setting delay time of more than 70 minutes is used in an amount of 0.7 to 3 parts by weight as an amount necessary for extrusion molding, (normal curing causes defective curing of cement due to moisture migration and evaporation in the molded body. 45-70 as difficult temperature
At a short curing time of 1 to 5 hours after the primary curing after extrusion molding, the hardening due to the setting of cement does not proceed, and the strength required when the primary curing product is conveyed to the autoclave curing device is expressed. Therefore, the productivity may be extremely reduced because it collapses. Hydroxyethyl group substitution degree is 45%
When the following cellulose ethers are used, the extrusion moldability at high temperature is not sufficiently exhibited, and it is difficult to achieve the object of the present invention. The method for producing hydroxyethyl cellulose used in the present invention is, for example, sufficient dispersion of the raw material cellulose powder in an organic dispersion medium such as ethylene glycol, and a 40% or more aqueous solution of NaOH having the same molar ratio or more to the cellulose powder. After adding and evacuating the system, ethylene oxide as an etherifying agent was added in the same molar ratio as the charged cellulose or more, and the mixture was stirred and mixed to raise the temperature from 40 ° C to 50 ° C over 6 hours in an autoclave. However, the present invention requires that the hydroxyethyl group be uniformly substituted in this reaction step. For example, NaOH
After impregnating the catalyst into the cellulose very heterogeneously, a large amount of etherifying agent such as ethylene oxide was added to cause rapid reaction, and even if a hydroxyethyl group substitution degree of 45% or more was obtained, retardation of the setting was delayed. Time exceeds 70 minutes, 1
This is because it will be over 00 minutes. The viscosity of a 2% aqueous solution corresponding to the degree of polymerization of hydroxyethyl cellulose at 20 ° C. is set to 15,000 cp or more by allowing the extrusion molding composition to coagulate until the cement hardens in extrusion molding at high temperature. Is necessary for.

In the non-asbestos cement-based extrusion molding composition of the present invention, in addition to the above-mentioned hydroxyethyl cellulose as a binder, polyvinyl alcohol or polyacrylamide having a short cement hardening delay time does not increase the primary curing time after molding. You may add in the range. The cement binder used in the above composition includes ordinary Portland cement, blast furnace cement, fly ash cement and the like. In addition, although early-strength cement such as alumina cement cannot be used, it is not preferable because it may be hardened during extrusion molding and cannot be molded. Further, silica stone, pearlite, or the like having a particle diameter close to that of cement may be mixed and used. Examples of non-asbestos fibers include various fibers such as glass fibers, which give shape-retaining properties and curing strength required for molded articles, but from the viewpoint of cost and performance, in particular, among them, pulp fibers Polypropylene fibers are preferred. The amount of these non-asbestos fibers added is preferably 0.5 to 10% by weight of the cement binder in view of the above-mentioned shape retention and strength.

It is preferable that the temperature of the molded product during extrusion molding of the above composition according to the present invention is as low as possible in order to increase the expressed viscosity of the binder and to prevent cracks in the molded product, but as a temperature at which the effect of the present invention can be found. Is above 30 ° C.

[0012]

【Example】

Examples and Comparative Examples 45 parts by weight of cement, 21 parts by weight of silica stone and Tables 1 and 2
Polypropylene fiber (manufactured by Daiwabo, 2d x 6
mm) or pulp fiber (wood fiber having a length of 0.5 to 4 mm, hardwood pulp [Junyu Pulp Co., Ltd.] crushed with an experimental cutting mill [Fritche Japan Co.])
And water-soluble cellulose ether were mixed with a Henschel mixer at 500 rpm for 3 minutes, water with the composition shown in Tables 1 and 2 was added, and the mixture was further kneaded with a 10-liter double-arm kneader for 5 minutes, and then extrusion-molded. Width by machine (made by Ishikawa Tokisha)
A plate having a thickness of 75 mm and a thickness of 6 mm was extruded. The molding state at that time was observed, and when the plate had no cracks, it was marked with ◯, and when it had cracks, it was marked with x. In addition, the above-mentioned molded body is treated at
% Was the primary curing time, and the time required for the bending strength to prevent collapse even when lifted was defined as the primary curing time. The above results are also shown in Tables 1 and 2. In the table, HE
C is hydroxyethyl cellulose and HPMC is hydroxypropyl methylcellulose, both manufactured by Shin-Etsu Chemical Co., Ltd.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

According to the present invention, non-asbestos cement type extrusion molding at high temperature can be performed with high productivity without increasing the curing time after molding.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C04B 28/02

Claims (1)

[Claims] 1. An extrusion molding composition in which 0.7 to 3% by weight of hydroxyethyl cellulose is added as a binder to a mixture of non-asbestos fibers and a cement binder, wherein the hydroxyethyl cellulose has a substitution degree of hydroxyethyl groups of 45. % Or more, 2% aqueous solution has a viscosity at 20 ° C of 15,000 cp or more, and a cement paste consisting of 100 parts by weight of ordinary Portland cement and 100 parts by weight of water, and the initial setting of cement as measured by JIS R-5201. It is expressed as the difference between the intermediate value A of the final measured values and the initial value of the cement setting measured by the same method as above with respect to the cement paste to which 0.2 part by weight of hydroxyethyl cellulose was added and the intermediate value B of the final measured values. Non-asbestos cement extrusion molding characterized by using a setting delay time of 70 minutes or less Composition.