JPS6256348A - Alumina base fiber formed body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a molded article of alumina fibers.
In particular, it relates to a molded article useful as a fireproof heat insulating material.

<Prior Art> Alumina fibers have excellent heat resistance and are prized as fire-resistant insulation materials. Commonly used inorganic oxides g! The molded products of fireproof insulation materials made of fibers include plate-shaped products called boards and felt made by bonding fibers with a binder, and non-woven fabrics called blankets made by accumulating fibers and subjected to needling. There are products with shapes.

However, it has not been used as a nut containing an alumina component of bzN or higher. The reason for this is that alumina fibers containing 65 liters or more of alumina do not form a blanket in which the fibers are entangled with each other even if they are aggregated and needled.

6! As is well known, alumina fibers containing % or more of alumina are produced exclusively by a precursor fiberization method. This method uses aluminum compounds as the main component,
Alumina fibers are produced by spinning a viscous solution containing a small amount of a bound polymer such as polyvinyl alcohol to produce raw fibers, and then converting the raw fibers into alumina fibers by firing the raw fibers. be done.

One of the inventors of the present invention has spent more than 6 years on producing a raw fiber blanket by first needling an accumulated raw fiber, and then firing the raw fiber to convert the raw fiber into an alumina fiber. It has been found that it is possible to produce an alumina-based blanket containing an alumina component of (
(See patent application 1/91, 77g%, 7711)
.

<Problems to be Solved by the Invention> The method according to the above-mentioned application has an extremely significant impact in that it provides for the first time a blankeratra of alumina fibers with a high content of alumina components. However, when the thickness of the plunged manufactured by this method increases, the tensile strength in the thickness direction, that is, the peel strength decreases, which severely limits its use.

According to the study by the present inventors, the reason for this low peel strength is that the fibers drawn into the inside from the surface during needling, that is, oriented in the thickness direction, are broken in the middle of the thickness direction. This is thought to be due to In other words, when an aggregate of raw fibers is needled by the conventional method, the fibers are pulled from the surface to the inside of the aggregate, so that in the area near the surface, there are a large number of fibers in the thickness direction depending on the number of needlings. Marginal fascicles are present. However, since these fibers break in the middle, the number of fibers in the thickness direction decreases from the surface toward the inside, and it is therefore considered that the peel strength of the finally produced blanket decreases.

Means for Solving the Problems The present inventors investigated a method for producing plunged alumina fibers with a large thickness and high peel strength and a high content of alumina. It was discovered that by applying an anti-friction agent and then needling, it was possible to produce a blanket that was thick and had high peel strength.
The invention has been completed.

In other words, the gist of the present invention is that the alumina component 6! It is a flat, non-woven fabric-like molded body made of alumina ffl fibers of S or higher, and most of the f&Km are arranged almost parallel to the flat plane of the molded body, and there is no surface on the flat plane. There are regular fiber bundles extending inward from the inside, and the thickness is 10 mm or more,
*k i:o, okel o, 3i/crd, tensile strength is o, skg/7 or more, peel strength is 0. ! rkg/
The present invention resides in an alumina fiber composition form characterized by having an alumina fiber composition of yn or more.

To explain the present invention in more detail, the fiber molded article according to the present invention is substantially composed of alumina fibers having an alumina component bz9f; oxides of metals may also be present.

Preferred alumina fibers contain 65 to 9 g of alumina, with the remainder consisting essentially of silica.

Alumina fibers generally have an average fiber diameter (classification unit: 1 μm).
The maximum value of the fiber diameter-fiber weight curve in m is 7 μm or less, and the maximum value of the fiber length-fiber weight curve in the average fiber length classification unit of 10 wn is 301 or more. If the average λ fiber diameter becomes too large, the fibers themselves become brittle and the breaking performance of the molded product decreases.

Moreover, when the average length m becomes thicker, the mechanical strength of the molded article decreases. The preferred average fiber diameter and average fiber length are:
They are 5 μm or less and 50 μm or more, respectively. J-3m
The presence of small fibers with an average fiber diameter of 0 μm is virtually impossible, and 50 μm.
1QllllIII with an average ta and fiber length of 1 or more
Particularly preferred are alumina fibers in which the abundance ratio 4 of rainbow short M fibers is 102 or less.

Molded body t''nJ 1f, large f6 of alumina fiber
The portions are arranged substantially parallel to the flat surface of the molded body. In other words, the alumina fibers are deposited almost in layers on the flat surface. The better the parallelism to the flat plane, the better the tensile strength of the molded body. On the other hand, the orientation of the alumina fibers in a plane parallel to the flat plane is determined by the physical properties r required of the molded product to be finally produced. That is, the tensile strength of the molded body is large in the direction in which the alumina 1M fibers are oriented, and is small in the direction perpendicular to this, so it is important to ensure that the alumina fibers are oriented in the direction where strength is required. If a molded article with small anisotropy, that is, a small difference in strength depending on the tensile direction is desired, the orientation of the alumina 1R fibers in a plane parallel to the flat plane may be made random.

Fiber bundles of alumina fibers extending from the surface toward the inside are regularly arranged on the flat surface of the molded body. Therefore, the ratio is usually 3 to -0 per 11, and the higher the number, the higher the density and peel strength of the molded product. These fiber bundles are intertwined with the alumina fibers that have dried up in the main body of the molded body, thereby exerting the mechanical L:ifL degree of the molded body, especially the peel strength.

The number of alumina fibers in one fiber is generally from SO to 400. This number of fibers depends primarily on the needles used for needling the raw fibers, and it is also possible to construct the fiber bundle with a number of 1, λ fibers outside this range.

The molded body has a thickness of 10 wg or more. The molded article according to the present invention is characterized by having high peel strength even at such a thickness. However, if the thickness of the molded body becomes too large, thread breakage during needling increases, making it difficult to maintain high peel strength.

Therefore, a molded body thicker than 8 calyxes is not preferred. The general thickness of the molded body is 10-! rOwm, preferably /
3~3! In order.

The molded body has a ratio of 0.07 to o, y y /a11. Preferably, it has a density of 0.0 g3 to o, tz g /ctlt.

Density is related to the heat insulating performance of a fireproof heat insulating material, but generally a molded article having a density within the above range can exhibit good heat insulating performance under various conditions.

The molded body has sufficient mechanical strength to be used as a fireproof heat insulating material. That is, the molded body has a tensile strength of at least o
, zkg/cdl, and has a peel strength of 0.5 kg/m or more. Preferably, the molded article has a tensile strength of 8 kg/cd or more, and a peel strength of 716 kg/cd or more. Further, the molded body has a size sufficient to be used as a fireproof heat insulating material, that is, at least a size of 0-71 ft (0, J corner x o, shoulder). Usually o, b m x to co m ~ 0.4 n
It has a size of x x 3.6 N.

The molded article according to the present invention is produced by accumulating raw fibers obtained by a precursor fiberization method in a layered manner, applying an anti-friction agent to the raw fibers, needling the raw fibers to form a blanket of raw fibers, and then firing the raw fibers. It can be produced by converting raw IR fibers into alumina fibers.

Production of raw fibers by the precursor fiberization method can be carried out according to conventional methods. According to the preferred method, a viscous molten g containing basic aluminum chloride (Atczn(oh)m-n) as a main component and containing silica sol and polyvinyl alcohol is heated by a high-speed flowing air stream. Green fibers are formed by extrusion from a tethered nozzle located therein. The thickness of raw fibers is generally several microns to tens of microns, and the length is several centimeters to several tens of centimeters, but specifically the alumina fibers required for the final molded product. Determined accordingly.

The raw fibers formed in the high-speed airflow are collected in layers on a wire mesh arranged perpendicular to the airflow.

The accumulation is lθ~i o 011 especially -〇~! r
It is preferable to have O-1 (all DjJL).Next, after applying an anti-friction agent of about 1 to 33 to the aggregate, the aggregate is stacked and needled to form a raw fiber blanket.As an anti-friction agent is high in rankrin rR% palmiti/Py, stearic acid, etc.

Esters of grade fatty acids 'k' are diluted with a hydrocarbon solvent such as mineral oil to about IQ times. Reduced M
The agent should be applied as uniformly as possible to the entire raw fiber. Needling is performed on both sides of the blanket in a conventional manner. The number of needling is generally 3 to 0 strokes/cIIl
In general, the larger the number of strokes, the higher the bulk density and peel strength of the final molded product. For example, if the bulk density of the molded body is desired to be (y, i y 1crtt),
The appropriate number of strokes for needling is 3 to 10 strokes/~. By needling, raw fiber particles are regularly arranged on the surface of the blanket from the surface toward the inside. Needling is preferably performed using a needle with a diameter as small as possible as long as the strength of the needle allows. If the diameter of the needle is large, there is an increased chance that the raw fibers will be cut by the needle, and the marks of the needle will remain as holes in the final molded product, which may reduce the heat insulation performance of the molded product. The size of the fiber bundle formed by needling depends on the hook provided on the needle.

Generally, one fiber Wf, 1: The number of constituent RR scarlets is 50
There are 200 to 200 books. The speed at which the needle enters the raw fiber during needling is preferably as small as possible as long as productivity allows. If this speed is too high, the raw material will be dragged by the needle and placed in the raw fiber. The fibers are cut in the middle, and the peel strength of the final molded product is reduced. The speed of the needle is normally 0! N/ OefR/ sea
, preferably from the range of 1 to j cat /sea.

When raw fibers are fired, they shrink and their water bulk increases, so
The bulk density and thickness of the raw fiber blanket may be set based on the bulk density and thickness required for the molded body, and the rice yield rate by firing. For example, if a molded article of o,/11/cu1 is desired, all raw fiber plugs may be produced with a decrease in thickness of about -θS and an increase in bulk density of about 20 light (raw fiber For details on the manufacturability of blankets, please refer to the "Manufacturing method for inorganic fiber blankets" filed by the applicant on July 16, 1985.
. The raw fiber blanket is then fired to above tioo'c to convert the raw fibers into alumina fibers. Firing temperature and final humidity temperature vary depending on the composition of the alumina fiber and the desired physical properties.

Firing takes about 2 hours to raise the temperature to yoo'c, then
It is appropriate to raise the temperature between 3oo-zoo°C at a rate of about u'c/min, then raise the temperature from 200°C to the final temperature at a rate of about 5°C/min, and maintain the final temperature for about J0 minutes. 300-20
If the temperature rises between 0°C and the temperature is too high, the mechanical strength of the resulting molded product will deteriorate. This is mentioned in the ``Tips (JA Manufacturing Method for Mechanized Composite Fibers'') filed by Rihito Honda on July 9th.

For example, the following is an example of the present invention. I will explain in more detail,
The present FVU is not limited to the following examples as long as the value does not exceed 7.

In addition, in the Kikiri 7141I book, the tensile strength and degree of peeling are determined by the following method: +=
So, there it is.

Measuring method of tensile strength and strength: +y, 8j Om % length/30 from the center of the molded body
- of - test specimens (a, b) are cut in a mutually orthogonal manner.

Fix both ends of the test piece in the length direction to a full strength testing machine, pull it in the vertical direction, and measure the maximum load (in g). The distance between both fixed ends is 100m1J1, and the pulling speed is: i
om1 minute.

From the measured values (n9) obtained above, the total tensile strength is calculated using the following formula.

1 1 0J Tensile strength (kq/cd!) = (offshore constant value of a) x τ From the center of the system',!;Ow, length 700U
One test piece ca, b) is cut out in directions perpendicular to each other. Peel off one length of the test piece in the thickness direction at a position i, about 3Q, and fix both yM in a frequency testing machine.
It is pulled in the vertical direction at 10 wa/min, and the maximum number of layers (v) at that time is measured. From this measured value (kg), calculate the peel strength (using the formula VC below).

Peel strength Ckv'm) = (measured value of trace value of a)
xτX Ryo Aluminum gold was dissolved in hydrochloric acid to form basic aluminum chloride (Al0In(OH)s-8), and silica sol was added thereto to prepare a solution containing the aluminum component and the silicon component 'Ie.

After assembling this, add it to water%Q' of polyvinyl alcohol to obtain an alumina-silica content of 30 (density M)
(Weight ratio)) Viscosity-wise, 2r00CP (Q raw material melt throat was obtained.

This raw material solution tfVj yarn nozzle high air permeability 5 is extruded into the yarn nozzle and spun, and the raw fibers flying on the air''; A thin raw fiber aggregate of about 3θy/go consisting of 4c~6μ, *sa,y □ -200wmO raw fibers was obtained.After adding an M-reducing agent to about 30y/go, it was layered and kneaded. The anti-friction agent is higher fatty acid ester 1.
Parts by weight were divided into parts by weight of mineral oil.

The number of strokes of needling was 5 strokes/-, and the resulting raw fiber bran foot was vertical. The size of A is 1000Xb! Om
, thickness was about 30cm, and the bulk was about 0.04mm, ogy/C waste.

This was placed in a furnace maintained at a temperature of about 3θθ°C, and maintained for one hour to bring the temperature inside to 300°C. Then, the ambient temperature was increased from 300 to 550°C at a total rate of C/min, ssθ~/-
The temperature was raised sequentially at a total rate of 5°C/min for 50°C, /2J? At θ℃,
Calcination was completed with 70 molecules retained.

The obtained alumina fiber molded body has a fiber diameter of 3 to qμ,
The thickness is about ko! rm, bulk density is approximately 0. /I/7, tensile strength is 1. λtr, q / 7, peeling strength /, J to g
/nn.

The tensile strength and peel strength were measured using the Shimadzu Corporation's electric measuring and controlling universal testing machine Autograph.

Further, the number of fibers in the seven fiber bundles was approximately 1 to 30.

[Brief explanation of drawings]

The figure is an explanatory diagram of a method for measuring peel strength.

Claims (6)

[Claims] (1) A flat non-woven molded body made of alumina fibers with an alumina content of 65% or more, most of the fibers being arranged almost parallel to the flat plane of the molded body, and the flat surface has a surface. There are regular fiber bundles going inward from the
Thickness is 10mm or more, density is 0.07-0.38/cm
^3. An alumina fiber molded article characterized by having a tensile strength of 0.5 kg/cm^3 or more and a peel strength of 0.5 kg/m or more. (2) Thickness is 15~35mm, density is 0.085~0.
15 g/cm^3 The alumina fiber molded article according to claim 1. (3) The alumina fiber molded article according to claim 1 or 2, wherein the alumina fiber is composed of 65% or more of an alumina component and the remainder substantially of a silica component. . (4) The fiber bundles that are regularly present on the flat plane from the surface toward the inside are the same as the fibers of the main body, and are arranged by needling. The alumina fiber molded article according to any one of Items 1 to 3. (5) Alumina fibers have an average fiber diameter of 7 μm.
The alumina fiber molded article according to any one of claims 1 to 4, wherein the fiber length is 30 mm or more on average. (6) The alumina fiber molded article according to any one of claims 1 to 5, wherein the area of the flat surface of the molded article is 0.27 m^2 or more.