JP2517393B2 - Cement extrusion molding composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a composition for cement extrusion molding using pulp as a substitute for asbestos, and more particularly to an extrusion composition with improved cement hardening failure.

(Prior Art) In recent years, by adding and kneading water to a mixture in which about 20 parts by weight of asbestos fibers and aggregates are added to cement, and extruding the mixture into a desired die shape, a cement board and , Asbestos / cement board, etc. are made and used as outer wall materials, roofing materials, floor materials, etc. of buildings. When asbestos fibers used in the production of such extrusion-molded products are added as reinforcing fibers, they are extremely well dispersed during kneading, and also have excellent shape-retaining performance to be given to the kneaded product during extrusion molding, and also have water-retaining performance. are doing. Also,
Even when curing with a steam pressure cooker at a temperature of 170 ° C or higher, which is performed to form the required strength if dimensional stability is imparted to the extruded product, it is possible to exert a sufficient effect as a strength reinforcing fiber due to the heat resistance of asbestos. it can.

As shown in the above, asbestos is a fiber that has at the same time the reinforcing fiber performance necessary for manufacturing an extrusion molded product, that is, dispersibility, shape retention, water retention, and heat resistance. It is used as a reinforcing fiber for.

However, in recent years, carcinogenicity that is thought to be due to the unique fiber shape with asbestos has become a problem,
It is desired to complete a technique for obtaining a good extruded product in a system in which asbestos is not used or the addition amount thereof is minimized. Organic fibers have already been investigated as alternatives to asbestos, but all have poor dispersibility, shape retention, and water retention performance, and many of them are poor in heat resistance because they are organic fibers, and high temperature steam. Some fibers cannot be pressure cured. Also, from the viewpoint of cost, those with good reinforcement strength are
It is considerably more expensive than asbestos, making it difficult to use fibers other than asbestos.

However, as for pulp fiber, it is a fiber that is naturally produced, and its cost is relatively low and its dispersibility is not as high as that of asbestos, but it is superior to other organic fibers. The amount added has the advantage that it is more adaptable to nailing and sawing, which was difficult with conventional asbestos / cement extrusion molding, and that it can be easily attached to building exterior materials, etc.
Pulp fiber is regarded as a promising alternative to asbestos.

On the other hand, even in the case of asbestos-containing cement extrusion molding, a lot of pressure is applied to the molding composition at the time of extrusion molding, and it is possible to perform good extrusion molding by uniformly retaining water in the molded body only by the water retention performance of asbestos. An organic binder is used because it is not possible and it is difficult to hold the molded product in its original shape by sticking the compositions to each other until the extrusion molded product is solidified and solidified.
Examples of these binders include water-soluble cellulose ethers such as methyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl cellulose and carboxymethyl hydroxyethyl cellulose, synthetic water-soluble polymers such as sodium polyacrylate and polyethylene oxide, and casein as described in JP-B-43-7134. In particular, alkyl cellulose and / or hydroxyalkyl alkyl cellulose, which has excellent dispersibility in cement, aggregate, etc., and has excellent water retention and adhesiveness, are mainly used. Even in the extrusion molding of cement containing pulp, it is essential to use these binders, for example, Japanese Patent Publication No. 55-51748 with a small amount of pulse fiber (cellulose fiber) added to glass fiber, There is a statement that a binder such as methyl cellulose is added, and in Japanese Examined Patent Publication No. 63-1276, cellulose extrusion molding in which spherical resin that has been temporarily foamed is added to pulp fiber (cellulose fiber) should be performed using a binder such as methyl cellulose. It is described that a molded body that can be sawed and nailed is obtained.

(Problems to be Solved by the Invention) However, when natural, particularly low-purity pulp fibers are added as in these patents, the lignin component remaining in the pulp fibers is eluted and the setting time of cement is significantly delayed. JP-A-63-256558 describes the use of a cement hardening accelerator. On the other hand, methyl cellulose, hydroxyalkyl methyl cellulose and the like are indispensable for extrusion molding in a pipe / cement system for water retention, shape retention and pulp dispersion as described above. 55-1958
As described in 1, the setting time of cement is delayed. For this reason, it is desirable to reduce the amount of cellulose ether used in order to prevent the molding composition from hardening and becoming difficult to mold during extrusion molding. However, in particular, in the pulp-containing cement extrusion molding, unless the addition amount of such methyl cellulose or hydroxyalkyl methyl cellulose is increased, extrusion molding is not possible. Therefore, in addition to the cement hardening retarding action by the lignin component in the pulp fiber, a large amount is added. However, there is a problem in that the cement curing failure occurs due to the addition of methyl cellulose or hydroxyalkyl methyl cellulose.

(Means for Solving the Problems) As a result of earnest studies on the facts, the inventors have found that
Cement extrusion by adding formalin condensate of alkyl sulfonate substituted or unsubstituted aryl sulfonate of 1 / 3-2 times that of alkyl cellulose and / or hydroxyalkyl alkyl cellulose added as a binder for cement extrusion The moldability of the composition is improved, the amount of binder added used can be reduced by 10-50%,
The present invention has been completed by finding that extrusion molding can be performed without curing failure due to delay of cement setting time.

The alkyl cellulose and / or hydroxyalkyl alkyl cellulose used in the present invention may be any water-soluble ones, such as methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl ethyl cellulose and ethyl cellulose. To be There is no problem as to the substitution degree as long as it is in the water-soluble substitution degree, and it is desirable that the methoxy content is 20-35% and the hydroxyalkyl content is 2-20%. JP 55-
As described in 19581, it is considered desirable to use cellulose ether with a high degree of substitution so as not to delay the setting of cement, but if the degree of substitution is too high, it becomes insoluble in water and the original extrusion moldability of cellulose ether is improved. No longer has the function of. As the viscosity of the aqueous solution corresponding to the molecular weight of cellulose ether, JIS Uberode viscosity system No. 4
Use a 2% aqueous solution with a viscosity of 8000 cps or more measured at 20 ℃. If the viscosity is less than 8000 cps, the viscosity is low, and even if the present invention is applied, extrusion molding becomes difficult unless an addition amount is used that delays the cement setting time by 100 minutes or more.

The formalin condensate of alkyl-substituted or unsubstituted aryl sulfonate used is conventionally known as an anionic surfactant, and commercially available products include Mighty 100 (manufactured by Kao Corporation) and Demol N (Kao). Atlas Co.) and the like. The amount added should be within 1 / 3-2 times the amount of binder used. If it is less than 1/3, the amount of binder added cannot be reduced by adding 2
Even if it is added more than twice, the effect does not change, so the addition becomes meaningless.

The addition amount of the binder used in the present invention is preferably a small addition amount so as not to delay the setting time of cement in particular, with respect to the extrusion molding material, 0.2
It is added in the range of -0.5% by weight. If it is less than 0.2% by weight, the binder effect cannot be exhibited, and extrusion molding will be poor. On the other hand, if it exceeds 0.5%, the curing of the molded product will be poor and the effect of the present invention will not be obtained.

The pulp fiber used in the present invention is pulverized to have a diameter of 5 to 20 μm and a length of 1 to 10 mm, and the pulp fiber is 3
Add in the range of -15% by weight. If you use pulp that is thinner or shorter than this range, or if the amount added is small,
Not enough reinforcing strength. If the pulp is thicker than this range, or if a long pulp is used, or if the addition amount is large, the fluidity of the kneaded product with the cement paste is extremely deteriorated, and thus a large addition amount of the binder is required. Lose purpose.

As the cement material used for extrusion molding, in addition to ordinary Portland cement, special cement such as alumina cement can also be used.

As the inorganic additive to be added in addition to the cement, silica sand, diatomaceous earth, it is possible to use any of the composition for extrusion molding suitable for the purpose such as weight reduction and reinforcing effect of brick-like material, as the addition amount, 10-60 parts by weight is desirable for 100 parts by weight of cement. As a reinforcing fiber to be additionally added, asbestos can be used. The addition amount thereof is preferably less than 5% by weight, and when it is 5% by weight or more, the fluidity of the molding composition is improved, so that extrusion molding can be performed with a low addition amount of cellulose ether even without the present invention.

As a reinforcing fiber other than asbestos, when using a 1-6 mm length cut product such as a synthetic fiber, the effect of the present invention is not impaired, but if too much is added, the necessary addition amount of cellulose ether also increases, so 5% It is preferably less than.

(Example) Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.

Examples 1 to 6 and Comparative Examples 1 to 7 Mixtures having the compositions shown in Tables 1 and 2 were kneaded with a double-arm kneader to obtain a width wider than that of Ishikawa Toki Co., Ltd.
A sheet having a thickness of 75 mm and a thickness of 6 mm was extrusion-molded and the moldability was compared.

Cement; Asano Ordinary Portland cement Silica stone; Toriyosha A class No.30 Average particle size 9-12μ Crushed product Pulp fiber is crushed with wood crushed wood pulp chips (5 mm square 2 mm thick) with an impact crusher (Victory mill), The diameter and length were adjusted as shown below.

Pulp fiber 1; diameter 8-15 μm, length 1-3 mm Pulp fiber 2; diameter 20-30 μm, length 15-20 mm Pulp fiber 3; diameter 3 μm, length 0.-0.8 mm Methylcellulose; Shin-Etsu Chemical Co., Ltd. Made by SM type Hydroxypropyl methylcellulose: SH type by Shin-Etsu Chemical Co., Ltd. Viscosity: 2% aqueous solution at 20 ° C JIS JIS Uberode viscometer No.4
Moldability: Molded product was cut at both ends x, and not cut was evaluated as ◯.

Surface condition: The one in which the pulp was protruding and the surface was uneven was evaluated as ×, and the one without the unevenness was evaluated as ○.

Nailability: After extrusion molding, the molded body was cured at 25 ° C and cured at 180 ° C in an autoclave, and a nail with a diameter of 3 mm was hammered into the molded body, and the molded body was not cracked.
And

As shown in the attached table, the compositions for cement extrusion molding of Examples 1 to 6 have a short curing time, moldability, surface condition,
Good nailability was obtained.

(Effects of the Invention) The composition for cement extrusion molding of the present invention improves the moldability and shape retention immediately after extrusion molding, and efficiently extrudes an extrusion molded article using pulp without delaying the curing time after molding. It can be manufactured well.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C04B 24:22) C04B 24:22) C (56) References JP-A-61-53141 (JP, A) Special features Kai 62-138350 (JP, A) JP-A-1-103939 (JP, A)

Claims (2)

(57) [Claims] 1. Extruded material, 3-15% by weight, diameter 5
-20 μm, length 1-10 mm pulp, 0.2-0.5% by weight of alkylcellulose and / or hydroxyalkylalkylcellulose, and 1 / 3-2 times the addition amount of said alkylcellulose and / or hydroxyalkylalkylcellulose A cement extrusion composition comprising an amount of a formalin condensate of an alkyl group-substituted or unsubstituted aryl sulfonate. 2. The composition for cement extrusion molding according to claim 1, wherein the viscosity of a 2% aqueous solution of alkyl cellulose and / or hydroxyalkyl alkyl cellulose at 20 ° C. is 8000 cps or more.