JPH02283646A - Cement composition for extrusion molding - Google Patents

Abstract

PURPOSE:To obtain the subject cement composition improved in shape retention by blending an inorganic additive containing cement with ground pulp fibers, an alkyl cellulose and/or hydroxylalkylalkyl cellulose and a formalin condensate of a specific allylsulfonate. CONSTITUTION:100 pts.wt. cement is blended with 10-60 pts.wt. inorganic additive such as silica sand to give an extrusion molding material. Then the molding material is blended with 3-15wt.% ground pulp fibers having 5-20mum diameter and 1-10mm length, 0.2-0.5wt.% alkyl cellulose and/or hydroxylalkylalkyl cellulose such as methyl cellulose or hydroxypropylmethyl cellulose having >=800cps viscosity in 2% aqueous solution at 20 deg.C as a binder and 1/3-2 times as much an anionic surfactant such as formalin condensate of alkyl-substituted or nonsubstituted allylsulfonate as the binder to give a cement composition for extrusion molding.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a cement extrusion molding composition using pulp as an asbestos substitute, and particularly to an extrusion molding composition that improves cement hardening defects.

(Prior art) In recent years, cement plates have been produced by extruding a mixture of cement, about 20 layers of asbestos fibers, aggregates, etc., adding water and kneading the mixture into a desired die shape. Also, asbestos/cement boards are made and used for building exterior wall materials, roofing materials, flooring materials, etc. When added as reinforcing fibers, the asbestos fibers used in the manufacture of such extrusion molded products have extremely good dispersion during kneading, have excellent shape-retaining properties for the molded products during extrusion molding, and have excellent water retention properties. It also has Also,
Even when asbestos is cured in a steam pressure cooker at temperatures above 1706 C to impart dimensional stability to extruded products and build the necessary strength, the heat resistance of asbestos allows it to exhibit sufficient effects as a strength-reinforcing fiber.

Asbestos is unique as a fiber that has the reinforcing fiber properties necessary for the production of extrusion products, such as dispersibility, shape retention, water retention, and heat resistance, as shown above. It is used as a reinforcing fiber.

However, in recent years, the carcinogenicity of asbestos, which is thought to be caused by its unique fiber shape, has become a problem, and the technology for obtaining good extrusion molded products without using asbestos or with as little amount of added asbestos as possible has become a problem. Organic fibers have already been considered as fibers to replace asbestos, but they all have poor dispersibility, shape retention, and water retention properties, and because they are organic fibers, they have poor heat resistance. Many fibers are bad, and some fibers cannot be cured under high temperature steam pressure.Furthermore, from a cost perspective, fibers with good reinforcement strength are considerably more expensive than asbestos, making it difficult to use fibers other than asbestos. It's becoming.

However, valve fibers are naturally produced fibers that are relatively inexpensive, and although their dispersibility is not as good as asbestos, they are superior to other organic fibers. Adding a small amount of asbestos has the advantage of increasing adaptability to nailing and sawing, which was difficult with conventional asbestos/cement extrusion molding, and making it easier to attach to building exterior materials. Bulb fiber is considered to be a promising fiber to replace asbestos.

On the other hand, in cement extrusion molding containing asbestos,
During extrusion molding, a lot of pressure is applied to the molding composition, and asbestos's water-retaining ability alone cannot uniformly retain water within the molded body and perform good extrusion molding, and the extruded molded product may coagulate and solidify. Since it is difficult to make the compositions adhere to each other and hold the molded article in its original shape until the molding process is completed, an organic binder is used. These binders include water-soluble cellulose ethers such as methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, and carboxinmethylhydroxyethylcellulose; synthetic water-soluble polymers such as sodium polyacrylate and polyethylene oxide; Casein etc. have been proposed,
Among these, alkyl cellulose and/or hydroxyalkylalkyl cellulose are most often used because they have excellent dispersion performance for cement, aggregate, etc., and excellent water retention performance and adhesiveness. The use of these binders is also essential in the extrusion molding of cement containing bulbs. For example, in Japanese Patent Publication No. 55-51748, a small amount of bulb fiber (cellulose fiber) was added to glass fiber. There is a description that a binder such as methylcellulose is added, and furthermore, in 1276/1987, cement extrusion molding is performed by adding foamed spherical resin to bulb fibers (cellulose fibers) using a binder such as methylcellulose. It is described that a molded body that can be sawed and nailed can be obtained by doing so.

(Problem to be solved by the invention) However, as in these patents, when natural valve fibers with a particularly low degree of purification are added, the lignin components remaining in the valve fibers are eluted, significantly delaying the setting time of cement. , JP-A-63-256558 describes the use of a cement hardening accelerator. On the other hand, methylcellulose, hydroxyalkylmethylcellulose, etc. are indispensable for extrusion molding in valve/cement systems for water retention, shape retention, and valve dispersion, as mentioned above. 5
5-19581, it causes a delay in the setting time of the cement. Therefore, in order to prevent the molding composition from hardening during extrusion molding and making molding difficult, it is desirable to reduce the amount of cellulose ether used. However, especially in the extrusion molding of cement containing bulbs, extrusion molding is impossible without adding a large amount of methylcellulose or hydroxyalkylmethylcellulose. There was a problem in that cement hardening failure occurred due to the addition of methylcellulose or hydroxyalkylmethylcellulose.

(Means for Solving the Problems) In view of this fact, the present inventors have conducted intensive studies and found that 1/3 to 2 By adding double the formalin condensate of substituted or unsubstituted allyl sulfonate, the moldability of the cement extrusion composition can be improved, the amount of binder added can be reduced by 10-50%, and the cement setting time can be reduced. It was discovered that extrusion molding can be performed without curing failure due to delay, and the present invention was completed.

The alkyl cellulose and/or hydroxyalkyl alkyl cellulose used in the present invention may be of any type as long as it is water-soluble, and examples thereof include methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl ethyl cellulose, and ethyl cellulose. It will be done. There is no problem as long as the degree of substitution is within the range of water solubility, and methoxy content is preferably about 20-35%, and hydroxyalkyl content is preferably about 2-20%. As described in JP-A-55-19581, 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 water-insoluble and the original cellulose ether becomes It no longer has the function of improving extrusion moldability. The viscosity of the aqueous solution corresponding to the molecular weight of the cellulose ether is one in which the viscosity of a 2% aqueous solution at 20°C measured by JIS Ubbelohde viscosity system No. 4 is 8000 cps or more. If the viscosity is less than 8,000 cps, the viscosity is low (even if the present invention is applied, extrusion molding becomes difficult unless the amount added is sufficient to delay cement setting time by 100 minutes or more.

The formalin condensate of alkyl-substituted or unsubstituted allyl sulfonate used is a conventionally known anionic surfactant, and the commercially available product is Mighty 1.
00 (manufactured by Kao Corporation) and Demol N (manufactured by Kao Atlas Corporation). The amount added is within 1/3 to 2 times the amount of binder used. If it is less than 173, the amount of binder used cannot be reduced by adding it, and even if it is added twice or more, there is no change in the effect, so the addition becomes meaningless.

The amount of the binder used in the present invention is desirably small so as not to particularly delay the setting time of the cement.
It is added in a range of -0.5% by weight. If it is less than 0.02% by weight, the binder effect cannot be exhibited and extrusion molding becomes defective. Moreover, if it exceeds 0.5% by weight, the molded article will show poor curing and the effect of the present invention will not be achieved.

The valve fiber used in the present invention has a diameter of 5-20μ and a length of 1
- It is ground to 10 mm and is added in a range of 3-15% by weight based on the extrusion molding material. If a bulb that is thinner or shorter than this range is used, or if the amount added is small, sufficient reinforcing strength will not be obtained.

Use a valve that is thicker or longer than this range, or
If the amount added is too large, the fluidity of the mixture with the cement paste will be extremely deteriorated, which will require a large amount of binder added, and the object of the present invention will not be achieved.

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

As inorganic additives to be added in addition to cement, any extrusion molding composition suitable for purposes such as silica sand, diatomaceous earth, brick materials, etc., can be used, and the amount to be added is as follows: The amount is preferably 10-60 parts by weight per 100 parts by weight of cement. Furthermore, asbestos can also be used as additional reinforcing fiber. The amount added 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 even without the present invention, extrusion molding is possible with a small amount of cellulose ether added.

When using synthetic fibers cut to a length of 1-6 mm as reinforcing fibers other than asbestos, the effects of the present invention will not be inhibited, but if too much is added, the required amount of cellulose ether will also increase, so 5% It is preferable to make it less than.

(Example) The present invention will be explained below with reference to Examples and Comparative Examples.

Examples 1 to 6 and Comparative Examples 1 to 7 Mixtures with the formulations shown in Attached Table 1.2 were kneaded using a double-arm kneader, and then a vacuum extruder Y-22 model manufactured by Ishikawa Co., Ltd. Sheets with a thickness of 6 rt>m were extrusion molded and the moldability was compared.

Cement: Asano Ordinary Portland Cement Silica Stone; Toriyasha A Grade No. 30 Average Particle Size 9-12μ Crushed Pulp fibers are wood pulp chips (5 mm square, thickness 2
mm) was pulverized using an impact pulverizer (Victory Mill), and the diameter and length were adjusted as shown below.

Pulp fiber 1: diameter 8-15μ, length 1-3mm Pulp fiber 2: diameter 20-30μ, length 15-20mm Pulp fiber 3: diameter 3μ, length 0.1-0.8mm Methyl cellulose: Shin-Etsu Chemical ( Co., Ltd. SM type hydroxypropyl methyl cellulose: Shin-Etsu Chemical Co., Ltd. (
Co., Ltd. SH type Viscosity: The 20°C viscosity of a 2% aqueous solution was measured using a JIS Ubbelohde viscometer No. 4. Molding property: The molded product was rated x if it was cut at both ends, and ○ if it was not cut.

Surface condition: A sample with pulp protruding from the surface and unevenness was graded as "X", and a sample with no bumps was graded as "○".

Nailing property: After extrusion molding, the molded product was cured at 25°C and autoclaved at 180°C, and a nail of 3 mm in diameter was driven into the molded product.
Those in which no cracks occurred in the molded bodies were rated as ○, and those in which cracks occurred were rated as ×.

As shown in the attached table, the cement extrusion molding compositions of Examples 1 to 6 had short curing times and had good moldability, surface condition, and nailing properties.

(Effects of the Invention) The composition for cement extrusion molding of the present invention improves moldability and shape retention immediately after extrusion molding, and improves the efficiency of extrusion molded products using pulp without delaying the curing time after molding. Can be manufactured well.

Patent applicant: Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. 3-15% by weight of pulp in the extruded material; 0.
A cement extrusion composition comprising 2-0.5% by weight of alkylcellulose and/or hydroxyalkylalkylcellulose and a formalin condensate of an alkyl group-substituted or unsubstituted allyl sulfonate. 2. The cement extrusion molding composition according to claim 1, wherein the 2% aqueous solution of alkylcellulose and/or hydroxyalkylalkylcellulose has a viscosity of 8000 cps or more at 20°C. 3. The amount of formalin condensate of alkyl group-substituted or unsubstituted allyl sulfonate added is 1/ of the amount of alkyl cellulose and/or hydroxyalkyl cellulose added.
The composition for cement extrusion molding according to claim 1, which is 3-2 times. 4. The composition for cement extrusion molding according to claim 1, wherein the pulp is pulverized to a diameter of 5 to 20 μm and a length of 1 to 10 mm.