JPS5857385B2 - Alkali-resistant inorganic fiber reinforced cement products - Google Patents

Description

[Detailed Description of the Invention] In order to improve the brittleness and tensile strength of molded products using cement, attempts have been made to mix fibers into cement and mold them, and a typical example of this is asbestos-cement composites. There is.

However, as asbestos is a natural product, the raw material has become depleted and the price has increased.In addition, restrictions on the environment in which it can be used have been tightened due to the risk of lung cancer if inhaled asbestos dust.
As a result, attempts have been made over the last dozen years to strengthen cement products with fibers other than asbestos, and recently, alkali-resistant glass fiber reinforced cement products have come into the spotlight.

However, although the alkali-resistant glass fibers used as reinforcing fibers for cement products are said to be alkali-resistant, their performance against alkalis is still inferior to that of asbestos, and the temperature applied during steam curing is limited to 60°C and 80 to 90°C.
If high-temperature steam curing is performed at 0°C, a drastic decrease in strength due to deterioration of the alkali-resistant glass fiber is unavoidable.

In addition, since alkali-resistant glass fibers are usually used in the form of chopped strands, the p-aqueous properties in the papermaking process of alkali-resistant fiber-reinforced cement products are as fast as F-water time of 1 minute or less, which improves cement retention. The ratio is as low as about 10%, and most of the cement is washed away. Moreover, the Young's modulus of the alkali-resistant glass fiber is too high, so when fiber-reinforced cement products are made into paper and molded, glass fibers protrude from the surface of the molded plate. It has poor formability.

Furthermore, alkali-resistant glass fibers are more expensive than asbestos, and there are still many deficiencies as a substitute for asbestos.

The present invention was made for the purpose of obtaining fiber-reinforced cement products with strength comparable to asbestos slate boards by using fibers that can be used as an asbestos substitute for asbestos-reinforced cement products such as asbestos slate boards. ,
As a result of various studies, the alkali-resistant IE inorganic fiber-reinforced cement product consisting of the composition described in the claims has been found to be comparable to asbestos-reinforced cement products, except for the various drawbacks of the conventional alkali-resistant glass fiber-reinforced cement board. We were able to obtain a reinforced cement product.

The alkali-resistant inorganic fibers that can be used as an asbestos substitute in the present invention include SiO2 40-50% by weight CaOO-10 Mg0 15-25 Fe2O
3+FeOO~10 〃 Al2O35~15 〃 MnO2~15// (However, CaO+ Fe 203 + FeO+ M
The total amount of nO must be less than 20% by weight), and it is made using inexpensive natural stone that can be sufficiently secured in terms of resources, and by the centrifugal R fiberization method using a multi-rotor. Form short fibers with a diameter of 2 to 10 microns.

Therefore, it can be manufactured at a cost equivalent to or lower than that of asbestos, and at about 1/10 of alkali-resistant glass fiber.

In addition, this alkali-resistant inorganic fiber has the shape of granular aggregated short fibers with an average diameter of 20 mm or less, making it possible to form molded plates, and has superior water resistance compared to asbestos, making it alkali-resistant glass fiber. Since the water drainage time is not too fast as in the case of the above, and it has a suitable water discharging property, it is possible to improve the molding p water property when molding asbestos-reinforced cement products and achieve improvements in production.

Furthermore, high-temperature steam curing at 80 to 90°C was possible, and a reinforced cement board comparable in strength to asbestos reinforced cement boards could be obtained.

Therefore, if S r 02 is less than 40% by weight in the above-mentioned inorganic fiber, it is impossible to obtain a fiber that satisfies alkali resistance and heat resistance in relation to the amount of basic oxide added.

Moreover, if it exceeds 50% by weight, the viscosity of the melt increases, making it difficult to form fibers by multi-rotor centrifugation.

CaO must be contained in an amount of less than 10% by weight for the purpose of improving fiber strength and heat resistance, and if it exceeds 10% by weight, heat resistance and other fiber properties deteriorate.

MgO is required in an amount of 15 to 25% by weight to compensate for the above-mentioned drawbacks of CaO and to provide a viscosity suitable for multi-rotor centrifugation.

Note that when MgO exceeds 25% by weight, the viscosity becomes too low and not only deviates from the appropriate viscosity, but also makes it impossible to maintain the required amount of acidic oxide, resulting in deterioration of alkali resistance.

On the other hand, if it is less than 15 □ by weight, the viscosity will increase, and the viscosity will deviate from the viscosity suitable for fiberization.

F e 203 and FeO are useful for improving heat resistance and obtaining flexible fibers when the fiber diameter is 2 to 10 μm, but when the amount exceeds 10% by weight, alkali resistance decreases.

Al2O3 is effective in improving the fiber strength when combined with SiO2, but when the amount added increases, the viscosity of the melt increases, the devitrification temperature increases, and the melting energy cost increases.

If it exceeds 15% by weight, alkali resistance will decrease.

Conversely, if it is less than 5% by weight, good fibers cannot be obtained.

By including MnO, effects that cannot be obtained with MgO can be obtained, namely, a uniform melt with very good meltability and good alkali resistance.

In the case of rock fibers, the blending amount is different from that of glass fibers, and even a content of 2 to 15% by weight has a sufficient viscosity lowering effect, and also exhibits stability and clarification of the melt.

As an example, a blend of 5% by weight has the effect of lowering the fiber conditioning temperature by about 80°C.

It is unnecessary to blend more than 15%, and at the same time,
If MnO is blended in a higher amount than this, it becomes impossible to secure the required amount of SiO2, which is undesirable from the viewpoint of fiberization of the melt.

Furthermore, if MnO is less than 2% by weight, properties as a fluxing agent are not exhibited, the viscosity of the melt increases, and the effect of adding MnO is not exhibited.

In addition to regulating the composition of the individual components mentioned above, MnO + Ca
The total amount of O + Fe 20s + F eo is 20% by weight
The reason for the following limitations is that a total amount of 20% by weight is sufficient to meet the appropriate fiberization conditions by multi-rotor centrifugation, that is, to reduce the viscosity to an appropriate viscosity. By adding
This is because the amount of 5I02 effective for alkali resistance must be reduced.

However, in order to produce sufficient fiber reinforcing effect in cement products, alkali-resistant inorganic fibers need to be used in an amount of 10 to 25% by weight; if it is less than 10% by weight, cement products will not have sufficient fiber reinforcing effect, and flame When exposed to it, an explosion phenomenon occurs and the dimensional change of cement products becomes extremely aggravated.

On the other hand, if it exceeds 25% by weight, the cost of the cement product will be high and the specific gravity will be low.

In order to supplement the fiber reinforcement effect of cement products reinforced with the appropriate amount of alkali-resistant inorganic fibers mentioned above, it is preferable to add asbestos up to 15% by weight, and if it exceeds 15% by weight, fiber reinforced cement products The ρ water resistance during papermaking becomes poor, and the purpose of the present invention, which is to replace asbestos with alkali-resistant inorganic fiber, is lost.

Pulp is required at 1 to 5% by weight to reduce the cost of cement products and improve cement retention during papermaking.
If it is less than 1% by weight, the retention improvement effect will not appear, and if it exceeds 5% by weight, problems will arise in terms of non-flammability, and there will also be a drawback that the dimensional change of the cement product will increase due to changes in humidity.

However, the total amount of asbestos and pulp is 0 to 15% by weight.
Must.

The reason for this is that if it exceeds 15% by weight, the cost of the cement product will increase, sweat resistance during papermaking will deteriorate, and the composition of the asbestos slate board and the cement product will not change.
The purpose of the present invention, which is to replace asbestos with alkali-resistant inorganic fibers, would be meaningless.

In order to maintain proper strength, cement requires a weight of 65 to 85%, and if it is less than 65% by weight, fiber-reinforced cement products will not have sufficient strength, whereas if it exceeds 85% by weight, fiber-reinforced cement products will not have sufficient strength. impact strength decreases.

Polypropylene fibers have no effect on bending strength, but adding them improves impact strength, so it is preferable to add up to 0.5% by weight; if it exceeds 0.5%, it becomes bulky and makes it difficult to form cement products. It doesn't work.

Examples will be explained in detail below.

First, as a comparative example, A S s 0239.4% (hereinafter not specified, all weight percentages are shown), Ca037.4%, Mg05.3
%.

Fe2O3+FeO, 0.5%, A720313.4%
.

Ordinary rock fiber with an average fiber diameter of 4.2μ with a composition consisting of T t 021.7% and other 2.3%, B %
S t 02473% corresponding to the lock fiber disclosed in JP-A No. 54-101922.

CaO3,4%, Mg023.6%e Fe 203
+FeO3.4%, A120392.5%* Ti
Alkali-resistant rock fiber with an average fiber diameter of 3.5μ with a composition consisting of 1.1% O2 and 2.6% others, C 810245.8% of the present invention, 3.6% CaO, M
g022.3%* Fe2O3+FeO3,1%, A1
2039.6%, Mn04.1%, TiO215%,
Three types of alkali-resistant inorganic fibers with a composition of 3.0% and an average fiber diameter of 3.3μ were selected, and D. ~50 (7) A composition consisting of 22% by weight of Hull 7' 3 Fi (chrysotile asbeth) 6D grade asbestos and 75% by weight of ordinary Portland cement was selected and designated as Experiment No. 1.

(b) The total amount of asbestos in the asbestos slate board with the above standard composition was replaced with A, B, and C, respectively, as experiment numbers 2 and 3.4, and (b) the asbestos in the asbestos slate board with the above standard composition was replaced with 5 Experiment Nos. 5 and 6.7 were obtained by binding the weight% and replacing the rest with A, B, and C, respectively.
The experiment number 8.9.10 is obtained by replacing the remainder with A, B, and C, respectively.

Water was added to each of the mixed solid compositions of Experiment Nos. 1 to 10 to adjust the slurry concentration to 5%, the mixture was stirred and mixed, and then the mixture was made into paper by reducing the pressure on a fourdrinier paper making machine.

After papermaking, it was press-molded using a press to produce a wet cloak with a thickness of 5 to 7 and a specific gravity of around 1.5.

This wet cloak can be used immediately at 60℃±3℃ or 90℃.
Steam curing was carried out for 24 hours at ℃±3℃, and then 20 hours.
The bending strength was measured after curing at room temperature for 4 weeks under the conditions of 'C and 70% RH.

The bending strength of the plate is 50mm wide, 200mm long, and 5mm thick.
Seven test specimens were measured using a Tensilon manufactured by Toyo Baldwin.

The test was conducted in accordance with JIS A1408 except for the sample size.

The bending strength of a specific gravity of 1.5 is determined by a specific gravity converter (squared) or d]
5 Calculated using PX(・ )2.

Here, P is the measured bending strength of O, d is the specific gravity, and do is the specific gravity of the test specimen.

The ingredient composition and characteristics of Examples and Comparative Examples are shown below in Clothing 1.

A fiber-reinforced cement board of the present invention consisting of 14% by weight of asbestos, 8% by weight of inorganic fibers (replacement rate 318%), 3% by weight of pulp, and 75% by weight of cement was prepared and subjected to similar tests, but during papermaking. Other than the ρ water time of 9 minutes, the physical properties of the obtained cement board were almost the same as those of the fiber-reinforced cement board with a substitution rate of 50%.

As is clear from Table 1, ordinary lock fiber is 60
It can be seen that the alkali resistance is poor even when steam-cured at 90°C, so the strength is lower than that of asbestos slate boards. However, the alkali-resistant inorganic fibers of the present invention can be used in any ratio with asbestos, and on the other hand, when cured with high-temperature steam at 90°C, It can be seen that up to half of asbestos can be replaced with the alkali-resistant inorganic fiber of the present invention.

As mentioned above, with regard to bending strength, it was found that by selecting an appropriate substitution ratio, an alkali-resistant inorganic fiber-reinforced cement board comparable to asbestos slate boards could be obtained, so impact strength was further investigated.

Impact strength is measured for fiber-reinforced cement boards cured with high temperature steam at 90°C, width 10mB, thickness 10mm, length 50mm.
A test specimen was prepared after being cured at room temperature for 4 weeks, and was measured using an Izot impact tester manufactured by Mori Shikenki Seisakusho.

The test specimens were those with the composition of experiment number 1.4.7.10 and those with the composition of experiment numbers 4 and 7.10, each with a fineness of 10.
A well-opened polypropylene fiber of denier and fiber length of 20vrrrb was added at 0.3% by weight,
Experiment numbers were 4', 7', and 10', respectively.

As is clear from Table 2, alkali-resistant inorganic fiber-reinforced cement boards generally have lower impact values than asbestos slate boards, but this can be improved by adding a small amount of polypropylene fibers, making them almost equivalent to asbestos slate boards. It can be seen that the impact value is .

Note that no effect on bending strength was observed even when polypropylene fibers were added.

As described above, the alkali-resistant inorganic fiber-reinforced cement product of the present invention can be produced industrially at low cost and can be used satisfactorily as a substitute for asbestos-reinforced cement products.

Claims (1)

[Claims] 1. Alkali-resistant inorganic fiber 10-25% by weight asbestos 0-15 Pulp
1-5〃Cement 65-85〃Polypropylene fiber 0-0.5//[However, the alkali-resistant inorganic fiber is Sin, 40-50% by weight
e Cao 0-10 wt%, Mg015-25 wt% *Fe2O3+FeOo ~1o wt%, Ad2
035-15% by weight, Mn02-15% by weight (and C
The total of aO+Fe2O3+FeO+MnO is 20% by weight
An alkali-resistant 1Jfl inorganic fiber reinforced cement product consisting of the following composition: