JP2000220037A - Amorphous inorganic fiber soluble in physiological medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber having higher heat resistance than a usual rock wool and >=40 of carcinogenic index (KI-value) with low accumulation in a human body while inexpesnsively and readily producible amorphous fibers resemble as rock wool. SOLUTION: This amorphous inorganic fiber soluble in a physiological medium contains >=85 wt.% of a total amount of SiO2 and CaO, 0.5-3.0 wt.% of MgO and 2.0-8.0 wt.% of P2O5 and having >=40 of KI-value by Germany dangerous article regulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous inorganic fiber having excellent heat resistance and solubility in a physiological medium such as a body fluid.

[0002]

2. Description of the Related Art Rock wool is obtained by adding a mixture of iron and steel slag and various raw materials to a mixture of silica, dolomite and the like as a component ratio adjusting material and heating and melting the same in a cupola or an electric furnace. It is an amorphous inorganic fiber obtained by fiberization by a method of blowing off with compressed air (blowing method), a method of colliding with a high-speed rotating body (rotor method), or the like. Its composition is generally SiO ₂ 35-4.
5 wt%, CaO30～40 wt%, MgO3～6 wt%, a FeO + Fe ₂ O ₃ 0.1~3 wt%, in addition, TiO _2, MnO as impurities derived from raw materials, N
Many of them contain a ₂ O, K ₂ O, S, etc. in a total amount of about 5% by weight.

[0003] This rock wool is a relatively inexpensive non-combustible fiber, and is widely used in the form of bulk fiber as a fireproof covering material or a high-temperature insulating material, and as a heat insulating material in the form of blankets, mats, felts, boards and the like. ing. However, the conventional general rock wool products are no more than 7
50 ° C. is the upper limit of the usable temperature, and at a higher temperature, it softens and melts, causing significant shrinkage and deformation. Therefore, in applications that are required to withstand a high temperature of 800 ° C. or more, various ceramic fibers such as silica-alumina must be used at present, but ceramic fibers are much more expensive than rock wool. It is.

[0004] Further, it has been found that various types of respiratory diseases may be caused when dusted ceramic fibers are inhaled by humans and accumulate in the lungs. In recent years, it has been applied to rock wool for the same reason. The cause of respiratory diseases caused by inorganic fibers such as ceramic fibers and rock wool is complicated, and many parts have not been elucidated. However, on the other hand, it is considered that if the inorganic fibers inhaled into the lungs are dissolved and absorbed in body fluids in a short period of time, they will be excreted out of the body at an early stage and the onset of respiratory diseases can be eliminated.

Considering the effect on human health, by increasing the solubility of inorganic fibers in body fluids, even if the dusted inorganic fibers are inhaled into the lungs, they do not accumulate and exert no harmful effects. It is desirable to do so. From such a viewpoint, importance has been placed on the solubility of inorganic fibers in body fluids. Specifically, there is a demand for a substance having good solubility in a solubility test performed using a physiological salt solution (for example, physiological saline) instead of a body fluid. In response to such demands, attempts have been made to improve body fluid solubility of rock wool-based amorphous inorganic fibers. For example, Japanese Patent Publication No. 7-42139 discloses that 0.1 to 30% by weight of MgO is used. , 0-10% by weight of A
By using l ₂ O ₃ and the balance of SiO ₂ and CaO, an alkaline earth metal silicate fiber having good solubility in a physiological salt solution is obtained. Also,
Japanese Unexamined Patent Publication No. Hei 8-511760 discloses SiO ₂ 40-6.
A biodegradable inorganic fiber containing 7% by weight and 20 to 45% by weight of CaO as essential components is disclosed. Further, JP-A-4-228455 discloses that 37 to 58% by weight of SiO2, _{7 to} 40% by weight of CaO, 4 to 16% by weight of MgO,
₂ O ₅ 1 to 10% by weight, Al ₂ O _{3 4 to} 14% by weight, Fe ₂
A biodegradable inorganic fiber containing _{4 to} 14% by weight of O ₃ as an essential component is disclosed.

On the other hand, in the regulation of dangerous substances in Germany, K is calculated from the chemical composition of inorganic fibers instead of the solubility test.
An index value called an I value (carcinogenicity index) is adopted as a criterion for judging the solubility of a body fluid and thus the safety. That is,
The value obtained by doubling the content (% by weight) of aluminum oxide from the sum of the content (% by weight) of each oxide of sodium, potassium, calcium, magnesium, barium and boron contained in the inorganic fiber composition To K
I value, the smaller the value, the higher the carcinogenicity, 4
If it is 0 or more, it is treated as having no fear of carcinogenicity.

For example, alumina silicate-based ceramic fibers can withstand high temperatures of 1000 to 1300 ° C., but are composed of 50% by weight of Al ₂ O ₃ and SiO _2.
Since it is around 50% by weight, the KI value reaches -100, it is chemically stable, and its resistance to physiological salt solution is extremely high. In addition, when exposed to a high temperature of 1000 ° C. or more, cristobalite, which is a kind of free silicic acid, is generated, and the fibers that produce the free silicic acid cause respiratory diseases such as silicosis. Therefore, it has been increasingly recognized that the alumina silicate-based ceramic fiber is a fiber harmful to the human body, and is classified as "category 2" fiber in the EU and Germany as "possibly carcinogenic to humans". And are subject to regulations. Further, the KI value of a general rock wool having the above-mentioned composition is much higher than that of the ceramic fiber, but still does not reach 40, and the solubility in a physiological salt solution is low. Therefore, regarding the harm when rock wool accumulates in the body, EU and Germany classify the fibers as "category 3" fibers "may be carcinogenic to humans" and are subject to the same regulations as ceramic fibers.

When the KI value of the above-mentioned biodegradable inorganic fiber is calculated by the same calculation, it is found that the KI value is as follows.
No. 139, the KI value is about 2
It is in the range of 0 to 50, and although the solubility in bodily fluids is improved as compared with general rock wool, many of them are not sufficient. The heat resistance is about 743-8.
Although it is described that it can be used continuously in the range of 15 ° C., it is described in Examples that it does not have much heat resistance. Is also considered to be slightly superior. In addition, the KI value of the inorganic fiber described in Japanese Patent Application Laid-Open No. 8-511760 is 40 or more when it is calculated for the examples. However, its heat resistance limit is recognized as about 700 ° C., which does not exceed that of conventional rock wool. In addition, Japanese Patent Application Laid-Open No. Hei 4-22845
The KI value of the inorganic fibers described in Japanese Patent Publication No. 5 does not reach 40 for all of the examples. Moreover, its heat resistance is comparable to that of conventional rock wool.

[0009] The KI value is spreading as an important safety criterion not only in Germany but also worldwide. Therefore,
Even when considering the improvement of heat resistance of rock wool, it is no longer possible to ignore the KI value. However, whether it is rock wool or ceramic fiber, it has high heat resistance to withstand high temperatures exceeding 800 ° C., and 4
An inorganic fiber satisfying a KI value of 0 or more has not yet been found.

[0010]

Accordingly, the present invention provides an amorphous inorganic fiber which is inexpensive and easy to produce as well as rock wool, but has heat resistance higher than that of conventional rock wool and has a KI value. An object of the present invention is to provide an inorganic fiber having a low accumulation in the human body of 40 or more.

[0011]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a semiconductor device having a total content of SiO ₂ and CaO of 8%.
5 is a% by weight or more, and containing a P ₂ O ₅ of 0.5 to 3.0 wt% of MgO and 2.0 to 8.0 wt%, and carcinogenicity index (KI value by the German hazardous substance regulations ) Is 40 or more. The present invention provides an amorphous inorganic fiber soluble in a physiological medium.

The novel amorphous inorganic fiber provided by the present invention has an improved KI value by containing SiO ₂ and CaO as main components, and has a KI value of MgO which is a component for improving heat resistance. By adding P ₂ O ₅ as an essential small component for improving heat resistance, excellent heat resistance such that the linear shrinkage at 800 ° C. is 5% or less, and physiological saline It has high biological solubility of 4% or more in water.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The amorphous inorganic fiber of the present invention contains SiO ₂ and Ca
A basic composition containing O as a main component is employed, and predetermined amounts of MgO and P ₂ O ₅ , which are effective for improving the heat resistance and KI value, respectively, are contained therein. . This is based on the following findings obtained in the process of examining a composition that can achieve the object of the present invention.

First, as a result of reconsidering the conventional main components of rock wool, Al ₂ O ₃ not only reduces the KI value but also significantly lowers the solubility in physiological saline. Therefore, it is necessary to reduce the amount of Al ₂ O ₃ as much as possible, and ideally, it is desirable to set it to zero. Although CaO is one of the main components in conventional ordinary rock wool, it increases both the KI value and the solubility in physiological saline. MgO is also a conventional ordinary rock wool component,
It is an advantageous component from the viewpoint of increasing the KI value, and is not limited at least. And so on.

As a result, first, the KI value and the physiological salt
As a fiber having a preferred composition from the viewpoint of water solubility, SiO
_TwoAnd CaO as main components, preferably a total of 85
Calcium silicate fibers that account for weight percent are considered
Was. To obtain a KI value of 40 or more in this composition, C
aO needs to be about 40% by weight or more. However
Et al. Reported that SiO containing 40% by weight or more of CaO_Two-CaO system
Fiber has poor heat resistance and can only be used at about 700 ° C
It is in the category of conventional rock wool. However, there
A small amount of P_TwoO_Five, The heat resistance is dramatically improved
800 ℃ above the heat resistant temperature of conventional rock wool
Fiber that can withstand
It has been certified. This is because Si in the fiber heated to high temperature
O _Two, CaO, MgO to wollastonite and diop
When crystals such as side are formed, P_TwoO_FiveIs a nuclear crystal
This causes the crystals to form quickly and the fibers themselves
The body is stiffened, resulting in fibers
It is considered to suppress the softening and shrinkage of. Therefore,
P_TwoO_FiveThe following tests were conducted to quantitatively determine the effects of
Was.

Table 1 shows the effect of P ₂ O ₅ on the heat resistance of the inorganic fibers containing SiO ₂ and CaO as main components. The specific evaluation method is as follows. First, 125 g of each inorganic fiber having the composition shown in Table 1 was stirred in 5 l of water using a drill mixer for 1 minute to disperse the fiber.
The mixture was stirred so as to have a concentration of t%, formed into a felt shape by a dehydration molding machine, and dried sufficiently at 105 ° C. and cut into a predetermined size to prepare a heating test sample. Then, mark the heating test sample with a ceramic pin,
After heating at 800 ° C. for 8 hours, the distance between the ceramic pins before and after the heating was measured, and the linear shrinkage (%) was determined from the following equation. Linear shrinkage _{(%) = (L O -L} 1) / L O × 100 where, L _0: the initial spacing of the test piece ceramic pin (mm) L _1: the interval after the heating test piece ceramic pin (mm )

[0017]

[Table 1]

The ratio of P ₂ O ₅ in the produced crystal (P ₂ O ₅₎
O ₅ ratio) was determined from the following equation, and the relationship between the P ₂ O ₅ ratio and the obtained linear shrinkage (raw value) was determined. In addition, the amount of produced crystals was the total value of CaO and MgO converted into their respective molar concentrations. P ₂ O ₅ ratio = P ₂ O ₅ / (CaO + MgO) (all calculated in terms of molar concentration) As shown in Table 1, it was confirmed that the linear shrinkage ratio decreased as the P ₂ O ₅ ratio increased. . This supports the above idea. It is considered that the crystallinity increases as the number of core crystals increases, and the linear shrinkage rate decreases due to the improvement in creep resistance.

[0019] FIG. 1 is a graph of the relationship between the indicated P ₂ O ₅ ratio and the coefficient of linear contraction in Table 1, the correlation was observed with the range of the relationship of the two, P ₂ O ₅ ratio 0.0
In comparison with 1, the linear shrinkage ratio is reduced by about 7.6%.
Further, in the present invention, an object of the present invention is to set the linear shrinkage ratio to 5% or less at a heating temperature of 800 ° C. as an index of the heat resistance performance.
_{The 2} O ₅ ratio is in the range of 0.02 to 0.05, and if the P ₂ O ₅ ratio is 0.02 or more, the linear shrinkage is considered to be 5% or less.

However, P_TwoO_FiveReduces saline solubility
Has the function of causing. This is because the phosphorus compound forms a film on the fiber.
Easy to form, resulting in more insolubles
it is conceivable that. Table 2 shows SiO 2_TwoAnd CaO as main components
Then P_TwoO_FiveAbout various inorganic fibers containing
The results of water solubility measurement are shown.
Fruit and P _TwoO_FiveThere is a very strong correlation with the content.
When both are subjected to regression analysis, P_TwoO_Five8 weight
% Or less, it is judged to have biosolubility
The solubility in saline becomes 4% or more. The physiological diet shown in Table 2
Salt water solubility, fiber sample ground to less than 200 mesh
1 g together with 150 ml of physiological saline was added to an Erlenmeyer flask (30
0ml) and placed in a 40 ° C incubator,
Horizontal vibration was applied at 120 rpm for 50 hours.
Excess and dried, weigh insoluble matter, and weigh the value before dissolution
Weight loss rate (% by weight) obtained by subtracting

[0021]

[Table 2]

As for other components, the solubility with physiological saline
There is no clear correlation, SiO _Two-CaO-P_TwoO_Five
-P in MgO system_TwoO_FiveThe concentration must be 8% by weight or less.
Is a reference having biosolubility.

As described above, it is recognized that there is a correlation between the P ₂ O ₅ ratio shown in FIG. 1 and the shrinkage ratio at 800 ° C., but as shown in FIG. On the other hand, it has a certain width (R ² = 0.73), the correlation is not defined only by the P ₂ O ₅ ratio, and other factors may be involved. One of the factors may be the presence of free SiO ₂ . Considering the fiber as an excessively viscous liquid, the contraction of the fiber is interpreted as fluidization due to heat. In order to suppress the fluidization of the fibers, it is necessary to make the viscous SiO ₂ exist not in the form of a compound but in a simple substance,
It is considered that when this amount increases, fluidization of the fiber, that is, shrinkage decreases. This free SiO ₂ (hereinafter referred to as excess SiO ₂₎
Is defined as follows. Excess SiO ₂ amount = SiO ₂ -CaO-MgO in fiber (all calculated in terms of molar concentration) This is the SiO linked to compounds such as wollastonite and diopside which have been crystallized by heating.
₂ shows a value obtained by subtracting the amount from the total amount of SiO ₂ .

Table 1 and FIG. 2 show the amount of excess SiO ₂ and 800
The relationship with the heating linear shrinkage rate (corrected shrinkage rate 1) is shown. still,
The value of the linear shrinkage in the figure, since the raw value, as described above there is the influence of P ₂ O _5, P ₂ of the fibers the raw value of the linear shrinkage by the slope of the regression line in Figure 1 This is a value obtained by correcting the O ₅ ratio to 0.035 (an intermediate point of the P ₂ O ₅ ratio in the 5% contraction region in FIG. 1) (hereinafter, referred to as a P ₂ O ₅ ratio corrected contraction rate) (positive value). ). The formula for calculating the P ₂ O ₅ ratio corrected shrinkage used in the correction calculation is shown below. P ₂ O ₅ ratio corrected shrinkage rate = raw value of each shrinkage rate + 7.6 × (each P
₂ O ₅ ratio−0.035) × 100

As shown in FIG. 2, excess Si
O ₂ of 1% per (P ₂ O ₅ ratio correction shrinkage -1.7%)
Of it is related, yet 800 ° C. heating Linear shrinkage illustrated in FIG. 1 (raw value) and a strong correlation was observed than the relationship between the P ₂ O ₅ ratio, excess SiO fiber shrinkage and P ₂ O ₅ ratio It can be confirmed that the amount is defined by _two quantities. As shown in the above formula for calculating the amount of excess SiO ₂ , this index is SiO ₂ , Ca
The O and MgO concentrations are defined. In FIG. 2, the value of the excess SiO ₂ amount at a corrected shrinkage of 5% is 7 to 10 mo.
1%. That is, when the value of the excess SiO ₂ amount is 7 mol% or more, the linear shrinkage rate is considered to be 5% or less.

However, although the correlation shown in FIG. 2 is not as good as the correlation shown in FIG. 1, a slight variation is recognized, and the shrinkage of the fiber is caused by the P ₂ O ₅ ratio and the excess SiO 2.
_It was thought that there was a competing factor in addition to the _two amounts, and that factor was determined to be MgO. In the present invention, SiO 2
_{To 2} -CaO-P ₂ O ₅ -MgO system satisfy the above KI value 40 is the sum of the CaO and MgO (wt%) needs to be 40 or more, the in the CaO and MgO Even if the total value is the same due to the difference in molecular weight, the amount of the product compound defined on a molar concentration basis is not the same, and the amount of the product compound increases as the amount of MgO having a small molecular weight increases. It is considered that when the amount of the produced compound increases, the crystallization of the fiber proceeds, the fiber becomes rigid as in the case of the effect of P ₂ O ₅ , the creep resistance is improved, and the shrinkage is suppressed. However, if the amount of MgO is too large, the amount of the MgO-based compound will increase. However, the compound generally has a large density, and is likely to shrink due to a difference in density from wollastonite which is a CaO compound. It is thought that it becomes. Therefore, it is considered that the MgO content in the fiber has a certain optimum range for suppressing the fiber shrinkage.

Table 1 and FIG. 3 show the MgO content (mo) in the fiber.
1%) and the 800 ° C. heating linear shrinkage ratio (corrected shrinkage ratio 2) corrected by the P ₂ O ₅ ratio and the excess SiO ₂ amount. As in FIG. 2, the raw value includes the P ₂ O ₅ ratio and excess Si.
Since the influence of the O ₂ amount exists, the P ₂ O ₅ ratio and the excess SiO ₂ amount corrected shrinkage ratio, which are values corrected in both cases, were calculated and used for analysis. The formulas for calculating the P ₂ O ₅ ratio and the excess SiO ₂ amount corrected shrinkage are shown below. P ₂ O ₅ ratio, excess SiO ₂ amount corrected shrinkage ratio = P ₂ O ₅ ratio corrected shrinkage ratio + 1.7 × (each excess SiO ₂ amount−8.5) × 100 8.5 shown in FIG. The intermediate value in the optimum range of the excess SiO ₂ amount obtained in the above was used. As shown in FIG.
Looking at the relationship between the gO concentration and the corrected shrinkage, the shrinkage decreases when the MgO concentration is in the range of 1 to 4 mol%, and the shrinkage increases when the MgO concentration is higher. That is, it supports the concept of the MgO effect.

From the above considerations, in the amorphous inorganic fiber of the present invention, the total of SiO ₂ and CaO is 85% by weight, and P ₂ O ₅ which is a component for improving heat resistance has a molar concentration of Using the index of P ₂ O ₅ / (CaO + MgO) calculated by the following formula, it is 0.02 or more from FIG.
Is 8% by weight or less from the viewpoint of the solubility in physiological saline shown in (1). In addition, MgO, which is also a heat resistance improving component, is shown in FIG.
The molar concentration is 1 to 4 mol%. Furthermore, SiO
₂ and CaO, the excess SiO ₂ amount, which is an index defined by SiO ₂ —CaO—MgO (molar concentration), is 7 mol from FIG.
%. Then, in such a composition range, when the composition ratio at which the KI value is 40 or more is calculated,
When the total content of O ₂ and CaO is 85% by weight or more, Mg
O is 0.5 to 3.0% by weight, P ₂ O ₅ is 2.0 to 8.0% by weight, and more preferably, SiO ₂ is 51.0 to ₅ % by weight.
8.0% by weight, CaO is 37.0 to 43.0% by weight, P
₂ O ₅ is 2.0 to 8.0% by weight, and MgO is 0.5 to 3% by weight.
0% by weight (but not more than 100% by weight in total). Thus, an amorphous inorganic fiber of the present invention having excellent physiological saline solubility having a KI value of 40 or more and heat resistance higher than ordinary rock wool was required.

In the production of the amorphous inorganic fiber of the present invention, when mineral raw materials are used, it is inevitable that many metal oxides besides the above-mentioned essential components are mixed, but it is desirable that they be as small as possible. Among them, Al which lowers the KI value
_The content of ₂ O ₃ is desirably at most 0.5% by weight, preferably 0.2% by weight or less.
It will be difficult to achieve the target values for water solubility and saline solubility. In addition, Na ₂ O, K ₂ O, BaO, B
_{If the amount of 2} O _{3 and the} like is large, the heat resistance is deteriorated.

The amorphous inorganic fiber of the present invention can be produced in exactly the same manner as conventional rock wool except that the raw materials and the compounding ratio are selected so that the chemical composition falls within the above-mentioned range. Suitable raw materials include quartzite (quartz), wollastonite, quicklime, slaked lime, calcium carbonate, dolomite, magnesium oxide, magnesium carbonate, alkali metal or alkaline earth metal phosphate, calcium pyrophosphate, and the like. Mix these raw materials appropriately,
It may be heated and melted in an electric furnace or a cupola furnace, and fiberized by a well-known method employed in rock wool production such as a blow method or a rotor method. The obtained fiber can be collected by a conventional method, laminated, applied with a binder, cured, etc., formed into a board or other shape, and provided for uses such as a heat insulating material.

[0031]

EXAMPLES The present invention will be further clarified by the following examples. (Examples 1 to 5) Table 3 using wollastonite, monobasic calcium phosphate, silica sand and magnesium oxide as raw materials
As described above, after mixing these raw materials so as to satisfy the composition range of the present invention, the mixture was heated and melted in an electric furnace, fiberized by a blow method, and collected. The obtained fibers were examined for physiological saline solubility and heat resistance by the following methods.

[Solubility in physiological saline] 1 g of a sample obtained by pulverizing each fiber to 200 mesh or less is placed in an Erlenmeyer flask (300 ml) together with 150 ml of physiological saline, placed in an incubator at 40 ° C., and rotated at 120 revolutions per minute for 50 hours. Horizontal vibration was applied, followed by filtration and drying, and the insoluble matter was weighed, and the value was subtracted from the weight before dissolution to obtain the weight loss rate (% by weight) due to dissolution, which was defined as the physiological saline dissolution rate.

[Heat resistance test method] 125 g of each fiber was added to 5 l of water.
After stirring the mixture for 1 minute using a drill mixer in the flask and dispersing the fibers, a 2% PVA solution was added to a solid content of 0.0
Felt was added at 8 wt% and stirred, and a felt molded by a dehydration molding machine was used as a measurement sample. The molded felt was dried sufficiently at 105 ° C., cut into a predetermined size, and subjected to a heating test. In the heating test, the sample was marked with a ceramic pin, heated at each heating temperature for 8 hours, the distance between the ceramic pins before and after heating was measured, and the heating linear shrinkage (%) was determined. The formula for calculating the contraction rate is shown below. Linear shrinkage _{(%) = (L O -L} 1) / L O × 100 where, L _0: the initial spacing of the test piece ceramic pin (mm) L _1: the interval after the heating test piece ceramic pin (mm )

[0034]

[Table 3]

Table 3 shows the results of each test. In each of the examples, the solubility in physiological saline was good, and the linear shrinkage at 800 ° C. was 5% or less in the heat resistance test.
It can be seen that excellent heat resistance is exhibited even at a high temperature of 00 ° C. or higher.

(Comparative Examples 1-4) Using wollastonite, monobasic calcium phosphate, silica sand and magnesium oxide as raw materials, mixing them in the proportions shown in Table 4, heating them in an electric furnace, melting them, and using a blow method After fiberization, the cotton was collected. The obtained fibers were examined for physiological saline solubility and heat resistance in the same manner as in the examples. Table 4 shows the results.

[0037]

[Table 4]

From Table 4, it was confirmed that the amorphous inorganic fibers outside the composition range of the present invention did not satisfy both physiological saline solubility and heat resistance even if the KI value was 40 or more.

[0039]

As described above, the amorphous inorganic fiber according to the present invention has a composition having a KI value of 40 or more, which is considered to be desirable in the regulation of dangerous goods in Germany, has excellent solubility in physiological saline, and As well as the conventional rock wool, it can be manufactured at low cost, but has a high heat resistance exceeding the common sense of the conventional rock wool.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of the amount of P ₂ O ₅ added on the heat resistance of an amorphous SiO ₂ —CaO—P ₂ O ₅ —MgO inorganic fiber.

FIG. 2 is a graph showing the effect of free SiO ₂ on the heat resistance of amorphous SiO ₂ —CaO—P ₂ O ₅ —MgO inorganic fibers.

FIG. 3 is a graph showing the effect of the amount of MgO added on the heat resistance of the SiO ₂ —CaO—P ₂ O ₅ —MgO-based amorphous inorganic fiber.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Sasaki 1-2-26 Shibadaimon, Minato-ku, Tokyo (72) Inventor Hideki Kitahara 1-2-1 Shintoda, Hamamatsu-shi, Shizuoka F-term (reference) 4G062 AA05 BB01 DA06 DB01 DC01 DD03 DE01 DF01 EA01 EB01 EC01 ED02 ED03 EE05 EF01 EG01 FA01 FA10 FB01 FC01 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HHH HH HH HH HH HH HH HH HH HH HH HH HH HH KK07 KK10 MM01 NN31 4L037 CS23 CS34 FA02 FA05 PA41 PF07 UA06

Claims (4)

[Claims] 1. The total content of SiO ₂ and CaO is 85.
At least 0.5% by weight, containing 0.5 to 3.0% by weight of MgO and 2.0 to 8.0% by weight of P ₂ O _5, and has a carcinogenicity index (KI value) according to the German Dangerous Substances Regulation. Amorphous inorganic fibers soluble in a physiological medium, wherein the inorganic fibers are 40 or more. _{2. An amount} of 51.0 to 58.0% by weight of SiO ₂ ,
37.0-43.0% by weight of CaO, 0.5-MgO
3.0 wt%, soluble amorphous inorganic fibers to physiological medium according to claim 1, characterized in that it contains P ₂ O ₅ 2.0 to 8.0 wt%. 3. The amorphous inorganic fiber soluble in a physiological medium according to claim 1, wherein the linear shrinkage at 800 ° C. is 5% or less. 4. The amorphous inorganic fiber soluble in a physiological medium according to claim 1, having a solubility in physiological saline of 4% or more.