JP2001139340A - Method for manufacturing rock wool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing rock wool capable of simultaneously achieving the reduction in the diameter of fibers and the decrease of unfiberized parts. SOLUTION: In the method for manufacturing the rock wool which allows a melted body formed by using blast furnace slag as a main raw material and subjecting the same to compound regulation to flow down on a rotating body rotating at a high speed and splashes the melted body by utilizing the centrifugal force of the rotating body to fiberize, the melted body regulated in viscosity so as to attain <=14 poises at 1,400 deg.C and 300 poises in a range of 1,200 to 1,250 deg.C is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing rock wool, and more particularly to a technique for producing rock wool having light weight and high heat insulation.

[0002]

2. Description of the Related Art In recent years, high insulation of houses has been promoted, and improvement in thermal efficiency has been desired. For this reason, a heat insulating material having a lower thermal conductivity than before and a lightweight heat insulating material is required from the viewpoint of workability and cost during construction.

As a typical heat insulating material, there has been an aggregate of inorganic fibers, and glass wool and rock wool are commercially available. Among them, rock wool is an inorganic fiber whose component is adjusted using blast furnace slag as a main raw material, and is a material that takes into account recent environmental issues in that it uses industrial by-products as a main raw material. In addition, since it has a higher softening temperature than glass wool, it is characterized by excellent heat resistance.
However, since the softening temperature is high, the heating temperature is higher than that of glass wool and the like, and the cooling conditions are different during the production.

The rock wool is made linear by pouring a melt containing blast furnace slag (hereinafter simply referred to as slag) in a molten state as a main component onto a rotating wheel and scattering the melt in the rotating direction. Due to this manufacturing method, an unfibrillated portion called a shot remains at the tip of the scattered linear body. Due to the presence of this shot, rock wool is heavier than glass wool with few shots when compared with aggregates containing fibers of equal volume.

[0005] In general, the heat insulating material made of inorganic fibers is formed of folded short fibers and an air layer. In most cases, the volume ratio of the fibers is 10% or less.
The layer of air trapped between the overlapping fibers is key to insulation. In such a fiber-based heat insulating material, while the apparent specific gravity is in a certain range, the heat insulating property is improved by increasing the air space, but when the fiber is lighter than that range, the air gap increases and convection occurs in the air space. In addition, since the air itself enters and exits, the heat insulating property rapidly deteriorates. Therefore, it was difficult to achieve both weight reduction and high heat insulation.

[0006] However, this is not the only countermeasure, and attempts have been made to reduce the diameter of fibers and to reduce the non-fibrous portions. When the fibers are thin, the fibers are intricately entangled at the same weight, so that the convection of air is suppressed, and when the non-fibrous portion is reduced, the weight is simply reduced without changing the fiber structure This is because

[0007] Various studies have been carried out on the realization of these improvements to rock wool, and the main focus has been on improving the manufacturing conditions and optimizing the components and properties of the melt. It is.

[0008] As an improvement in manufacturing conditions, it is known to increase the centrifugal acceleration of the rotating wheel. This influences the initial condition when the melt is scattered, and the idea is that as the acceleration is increased, the fluctuation of the melt on the wheel becomes finer, whereby fine fibers are formed. The basics of this idea have been analyzed in the past,
For example, Tanazawa et al. Reported a paper on "fibrosis of liquid by rotating disk". Patent applications have also been seen, for example, Japanese Patent Application Laid-Open No. Hei 6-504256 discloses a 50 km / s
It discloses that an acceleration of ec ² or more is effective.
However, according to this manufacturing method, although the diameter of the fiber is surely reduced, the device may need to be modified or safety measures may be required, so that it cannot be applied to all the existing manufacturing devices.

On the other hand, regarding the optimization of the components and characteristics of the melt, the optimization of the components is essentially related to the adjustment of the characteristics. Hitherto, it has been known that decreasing the viscosity of the melt at 1400 ° C. to 1600 ° C. is effective in reducing the fiber diameter. This also specifies the initial condition of the melt at the time of starting scattering from the rotating wheel, as in the case of increasing the acceleration of the rotating wheel described above. This is a method for making the melt finer. Further, as a similar improvement method, a method of increasing the temperature of the melt to reduce the diameter is also known, but this is based on the fact that the viscosity of the melt decreases as the temperature increases. In terms of lowering the viscosity, it is a technology having the same concept as above.

The present applicant has respected the above-mentioned prior art and made various attempts to reduce the viscosity of the melt. As a result, it was confirmed that the fiber diameter tended to be small, and that the characteristics of the fiber were also improved to some extent. However, it did not lead to a significant improvement that satisfies the properties of the currently required heat insulating material. Subsequently, the reason was further examined, and it was found that even if the viscosity of the melt was reduced, the effect was not so large on the non-fibrillated portion (shot), and in some cases, it became worse. In other words, there is still room for improvement to simultaneously achieve a reduction in fiber diameter and a reduction in shots.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing rock wool which can simultaneously reduce the fiber diameter and reduce the non-fibrous portion.

[0012]

Means for Solving the Problems In order to achieve the above object, the inventor studied the behavior of the melt when it turned into fibers. Then, it has been found that not only the initial properties of the melt scattered from the rotating wheel but also changes during cooling before solidification are important for fiberization at the same time. Based on this finding, the viscosity and temperature history of the melt during the cooling process were investigated in detail, and the results were embodied in the present invention.

[0013] That is, the present invention provides a rock wool in which a melt whose component is adjusted using blast furnace slag as a main raw material flows down onto a rotating body that rotates at a high speed, and is scattered using the centrifugal force of the rotating body to produce fibers. Wherein the melt has a viscosity of 14 poise or less at 1400 ° C.
A method for producing rock wool, characterized in that a material having 300 poise in a temperature range of 1250 ° C. is used.

Further, the present invention is a method for producing rock wool, wherein the melt is adjusted to the following composition.

SiO ₂ : 42 to 48 wt%, CaO: 3
0~40wt%, MgO: 3~8wt%, Al 2 O 3: 1
_{0~20wt%, Na 2 O + K} 2 O: 1Wt%, further,
B ₂ O ₃ ≦ 5 wt% and / or Fe ₂ ≦ 6 wt%
O ₃ is contained in total exceeding 1 wt% or less.

In the present invention, the viscosity of the melt, which is a raw material, is limited to a predetermined range not only when scattering starts on the rotating wheel but also during the scattering or until the melt is cooled to a certain temperature. The melt flows until it is completely solidified, and the chance of becoming linear (longer time) increases. As a result, the manufactured fiber has a smaller diameter than before and the non-fibrillated portion also decreases.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the circumstances that led to the invention.

First, the inventor considered that the viscosity of the melt in the early stage of production had a great influence on the diameter of the fiber to be produced, and investigated the optimum range of the viscosity. Therefore, various additives were added to blast furnace slag (for the slag composition, see Table 1) to produce a melt in which the components were adjusted, and an experiment was conducted.

[0019]

[Table 1]

The temperature of the melt is about 1400 ° C. in consideration of the situation when the melt is injected from a rotating wheel (hereinafter simply referred to as a wheel). Since it was found that the characteristic can be represented by the characteristic at 1400 ° C., the viscosity of the melt at 1400 ° C. was adopted as the index value. FIG. 1 shows the relationship between the melt viscosity and the fiber diameter obtained in this investigation. From FIG. 1, 1400 ° C.
It is clear that the smaller the viscosity of the melt in the above, the smaller the diameter of the produced fiber. In addition, this result is 14 pois for the currently widely used rock wool.
e and below suggest that it is necessary to be 13 poise or less in order to obtain a further improvement effect. Note that the fiber diameter on the vertical axis is an average value obtained by measuring 100 or more fibers using a microscope, and the average value of commercially available rock wool is expressed as 100%.

On the other hand, the relationship between the viscosity of the melt at this temperature and the shot rate (unfibrillation rate) of the produced fiber was examined.
The relationship of FIG. 2 was obtained. The shot rate tends to increase slightly when the viscosity of the melt is low, but it has been found that the variation is much larger than the viscosity dependency. In other words, if the viscosity of the melt is low, the unfibrillated portion tends to remain, but it is not clear. Therefore, it is understood that the viscosity of the melt at a high temperature alone does not lead to an essential improvement in fiber properties, and that another means is required. The shot ratio was measured by crushing rock wool in water for 2 minutes, and then measuring the weight of shots of 45 μm or more. In FIG. 2, the shot ratio of a commercially available product is shown as 100.

Therefore, the inventor further studied effective means for lowering the shot rate.

The inorganic fiber is formed by a melt formed on a wheel forming a fiber nucleus due to fluctuations and trailing when the nucleus is blown off by centrifugal force. Judging from the fiber formation mechanism, the shot is a solid that remains inside the nucleus in the first liquid phase state without fibrillation as it is, and it is completely determined only by the properties of the melt at the start of scattering. It is thought that it cannot be lost. On the other hand,
Finding a way to eliminate shots while flying to a solid state, suggests that fiber properties may be significantly improved, compatible with thinning the fibers.

Therefore, the inventor worked diligently to find the means, and made the fluidity (that is, the viscosity low) of the melt up to a low temperature.
Was found to be held. FIG. 3 shows, as an example, the temperature change of the melt viscosity using slag as a main raw material. The melt in the high temperature state is cooled during scattering and becomes a fiber when the fluidity is lost, but in the case of the melt using slag as the main raw material, the viscosity rapidly increases when it drops to a certain temperature You can see that. In addition, the temperature at which the viscosity suddenly starts to increase may vary by as much as 50 ° C. depending on the melt, and it is estimated that this temperature difference greatly affects fiberization. Therefore, the relationship between the temperature at which the viscosity of the melt suddenly increases and the shot ratio of the produced fiber was examined. The results are shown in FIG. 4, and it was found that when the temperature at which the viscosity suddenly increases was lowered, that is, when the melt maintained a certain degree of fluidity at a lower temperature, the shot rate of the produced fiber was reduced.

On the other hand, maintaining a certain degree of fluidity up to a low temperature is advantageous for reducing the shot rate, but if the fluidity is maintained forever, the fibers once formed may come into contact with each other during scattering or cooling. Another problem arises in that the fibers are fused and coalesced and the fiber diameter becomes large. Therefore, when investigating the conditions under which the fusion and coalescence of the fibers are unlikely to occur,
The melt has a viscosity of 300 poise at 1200 to 1250 ° C.
It has been found that the above arrangement does not cause fusion and coalescence.

From these findings, the inventor of the present invention has found that as a melt for producing fibers, the viscosity is 1200 to 1250 ° C.
Was considered to be necessary, and was incorporated into the requirements of the present invention. In addition, the viscosity is 300 poise
When the temperature is set to 1200 ° C. or higher, there is also a secondary effect that the fire resistance of the obtained inorganic fiber is increased.

Incidentally, in order to set the viscosity of the melt to the above-described specific value, it is necessary to adjust the composition of the melt. Therefore, the inventor has made various trials of the adjustment, and found that blast furnace slag was used as a main raw material, and a suitable raw material was simply added to the molten slag to obtain the following composition.

SiO ₂ : 42 to 48 wt%, CaO: 3
0~40wt%, MgO: 3~8wt%, Al 2 O 3: 1
_{0~20wt%, Na 2 O + K} 2 O: 1Wt%, further,
B ₂ O ₃ ≦ 5 wt% and / or Fe ₂ ≦ 6 wt%
O ₃ is contained in total exceeding 1 wt% or less.

The adjustment may be carried out directly as described above, but it is preferable to add the ingredients for component adjustment while reheating in a melting furnace such as an electric furnace or a cupola immediately before scattering with a wheel. . This is because component adjustment can be performed more reliably.

The reasons for limiting each component as described above are as follows.

SiO ₂ : When blast furnace slag or converter slag is used as a main raw material, CaO as a raw material increases. In this case, it is difficult for the material in the molten state to maintain the glass state at a low temperature, and to compensate for this, it is necessary to make the SiO ₂ concentration of the material in the molten state 42% by weight or more. 42
If the amount is less than wt%, the non-fibrillated portion (the shot) increases rapidly in the fibrous body produced by scattering from the rotating body. Conversely, if the SiO ₂ concentration is too high, the viscosity of the material becomes high, the fluidity deteriorates, the production efficiency decreases, and the fibers become thick. Therefore, the upper limit is set to 48 wt%.

Na ₂ O and K ₂ O: In general, as a method for suppressing an increase in the viscosity of the composition, there is a method of adding a large amount of soda such as Na ₂ O or K ₂ O. Although this method is effective in suppressing the viscosity, in the case of rock wool, the heat resistance and water resistance tend to deteriorate, and the advantage of the rock wool is reduced. Therefore, in the present invention, the viscosity is adjusted by the SiO ₂ concentration of the material, and at the same time, the soda content is reduced as much as possible so that heat resistance and water resistance can be maintained. That is, N
the total content of a ₂ O and K ₂ O is decided to be limited to less than 1 wt%.

CaO: It is well known that CaO contained in a large amount in blast furnace slag and converter slag also has the effect of lowering the viscosity of a molten composition. As a result of examining the effect, it was found that if the content was 30 wt% or more, the low viscosity of the material at a high temperature could be maintained. Therefore, in the present invention, the lower limit of CaO was set to 30 wt%. But C
If aO becomes too large, the material cannot maintain a glassy state, so the upper limit is set to 40 wt%.

MgO: In general, MgO in the composition has an effect of reducing the devitrification of the glass and maintaining the heat resistance. Therefore, it is desirable that rock wool contains 3 wt% or more. On the other hand, because it is an alkaline earth system similar to CaO,
In the high CaO-based composition as in the present invention, MgO
If the content is too high, fibrillation becomes difficult (the reason why alkaline earth makes fibrillation difficult has not been described yet, so what to do). Therefore, the upper limit is Si
When O ₂ and CaO are in the above ranges, the content is preferably 8 wt% or less.

Al ₂ O ₃ : Al ₂ O ₃ is also similar to MgO,
It is effective for vitrification and high heat resistance, and a content of 10 wt% or more is desirable. However, it is known that the viscosity increases sharply when the content increases, and the SiO ₂ ,
If the composition level is CaO, it is desirably 20 wt% or less.

In the present invention, as described above, after optimizing the basic composition of the material, B ₂ O ₃ and Fe ₂ O ₃ are added,
Furthermore, the diameter of rock wool was reduced and shots were reduced.

B ₂ O ₃ : Like SiO ₂ , B ₂ O ₃ is an element having a strong tendency to vitrify. The addition of B ₂ O ₃ lowers the high-temperature viscosity, and at the same time, widens the vitrification region to a lower temperature to increase the shot ratio. Can be lowered. FIG. 1 shows the basic component system (SiO ₂
The _{-CaO-MgO-Al 2 O 3} ) shows the change in viscosity when the addition of B ₂ O _3. It is clear that the above effect appears when the amount of B ₂ O ₃ added is increased. It can be seen that as the amount of addition increases, the low-viscosity region extends up to low temperatures, and is effective for vitrification. However, if added in excess of 5 wt%, the heat resistance of rock wool will decrease, so that 5 wt%
Is desirably set to the upper limit.

The _{Fe 2 O 3: Fe 2 O} 3 , although effective in comparison with the B ₂ O ₃ is small, can be expected similarly reduced diameter. It has been known from the conventional knowledge that when iron oxide is added, the fiber strength at high temperatures is increased, which is also considered to work effectively. However, when the iron oxide component is too high, it results in coloring the glass, and from the operational problems such as accumulated therein reduced to the iron occurs as Fe ₂ O ₃ is 6 wt % Is desirably the upper limit. The contents of B ₂ O ₃ and Fe ₂ O ₃ are as follows:
It was also confirmed that the effect was obtained for the first time when any one of them or the total exceeded 1 wt%.

In addition, adjusting the atmosphere surrounding the fibers during the scattering of the melt was also effective in changing the characteristics of the fibers.
Furthermore, even if the physical properties of the melt are improved, if the effects of defects (for example, voids and pores) contained in the fibers remain, the effects are impaired. Therefore, it is more desirable to melt in an electric furnace before scattering to remove bubbles contained in the melt as much as possible.

[0040]

EXAMPLES Next, the present invention will be described specifically, but the present invention is not limited to these examples.

The blast furnace slag shown in Table 1 was melted in a two-stage electric furnace and mixed with silica, quicklime, iron ore, glass alate, etc., and adjusted to various chemical compositions. (7 types in Examples and Comparative Examples) were produced. These melts were heated and melted using a carbon electrode in the same electric furnace, and were scattered by being poured onto the surface of a high-speed rotating internal cooling type wheel. On the wheel surface,
The temperature of these melts is controlled to be 1400 ° C. to 1460 ° C., and the cotton (fibrous material) is separated from the wheel.
The cotton was collected by blowing compressed air (about 100 m / s) in the direction of the scattering. The cotton collection is performed by a cotton collection machine, where the cotton is air-cooled to room temperature. In addition, the time required from the start of scattering of a melt of 35 tons for one charge to the completion of cooling is 1 hour.
It was 0 hours.

Further, under the same conditions, the cotton wool is collected while spraying a water-soluble phenol resin binder from around the wheel at the time of scattering, and the collected wool is pre-compressed to form a plate.
The binder is cured in a thermosetting oven, and the bulk density is about 30k
An amorphous board of g / m ³ and 100 mm thickness was also manufactured.

The performance results are shown in Table 2 above.
The viscosity of the melt at 0 ° C., the temperature at which the viscosity becomes 300 poise or more, the diameter of the manufactured fiber, the shot rate, and the heat insulation (thermal conductivity) of the board are collectively shown.

[0044]

[Table 2]

The low-density fibrous body obtained by the production method according to the present invention is amorphous, and according to Table 2, it is clear that each fiber forming the fiber is thin and the shot ratio is low. is there. In addition, it can be seen that the thermal conductivity is low and high heat insulation is maintained. In other words, a building material that is lightweight and has excellent heat insulation properties can be developed.

[0046]

As described above, according to the present invention, rock wool having low density and high heat insulation can be stably manufactured. In addition, since blast furnace slag is used as a raw material, a high-quality heat insulating material can be provided at a lower cost for houses and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the viscosity of a melt used in a study and the diameter of a manufactured fiber.

FIG. 2 is a diagram showing the relationship between the viscosity of a melt used in the investigation and the shot rate of manufactured fibers.

FIG. 3 is a diagram showing a change in viscosity of a melt with temperature.

FIG. 4 is a diagram showing the relationship between the temperature at which the viscosity of a melt starts to rise sharply and the shot rate of manufactured fibers.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masato Kumagai 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute, Kawasaki Steel Corp. (72) Inventor Masaaki Sato 1-chome Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture None) Kawatetsu Rock Fiber Co., Ltd. (72) Inventor Masataka Yamada 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. DC02 DC03 DD01 DE01 DF01 EA01 EB01 EB02 EB03 EC01 EC02 EC03 ED03 EE05 EF01 EG01 FA01 FA10 FB01 FC01 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH00 HHH HH HH HH HH HH HH HH KK01 KK03 KK05 KK07 KK10 MM01 NN29

Claims (2)

[Claims] 1. A method for producing rock wool, in which a melt whose component has been adjusted using blast furnace slag as a main raw material flows down onto a rotating body that rotates at a high speed, and is scattered using the centrifugal force of the rotating body to produce fibers. The melt has a viscosity of 14 poise at 1400 ° C.
e, 300 pois in the range of 1200 to 1250 ° C
e. A method for producing rock wool, characterized by using: 2. The method for producing rock wool according to claim 1, wherein the melt is adjusted to have the following composition. _{SiO 2: 42~48wt% CaO: 30~40wt} % MgO: 3~8wt% Al 2 O 3: 10~20wt% Na 2 O + K 2 O: 1Wt% addition, 5 wt% or less of B ₂ O ₃ and / or 6wt % Of Fe ₂ O ₃ or less in total exceeding 1 wt% or less