JPH0274575A - Heat insulating fiber molded body and its production - Google Patents

Abstract

PURPOSE: To manufacture a heat insulating molded fiber body which has a good expansion characteristic by molding a refractory ceramic fiber mat from an aq. suspension and compounding superfine and unexpanded vermiculite and an organic fibrid in a specific proportion at this time.

CONSTITUTION: The fiber mat molded body is molded from an aq. suspension of ceramic fibers. At this time, the unexpanded vermiculite with a max. grain size of 0.1 mm is dispered into the suspension, and the molded body is allowed to contain the same as unexpanded vermiculite with a max. grain size of 1.0 mm. The fiber mat molded body is dried after compounded with the organic fibrid and a bonding agent, if necessary, and further, is heat-treated, thereby melting the organic fibrid to obtain the fiber mat. Into this, the ceramic fibers and vermiculite are compounded in a ratio of 80:20 to 30:70 and this is allowed to contain 5 to 40 wt.% organic fibrid. Thus, the heat insulating fiber molded body, which has a good expansion characteristic at high temp. modified expansion pressure and erosion resisitivity, is obtd.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is characterized in that the ratio of refractory ceramic fibers to ceramic fibers to permiculite is 80:20 to 30.
The invention relates to a thermally insulating fibrous molding consisting of 70% permiculite, 5 to 40% by weight, based on the total composition, of an organic polymer fipulid and a temporary and/or permanent binder.

[Conventional technology]

German Patent Application No. P 37 01 511.7 describes a thermally insulating shaped body of the above-mentioned type. In the production of the moldings described there using vermiculite, permiculite with a particle size of up to 2 mm is used.

[What the invention seeks to solve 8 1ai Jl, 0+am
If unexpanded permiculite is used, with a maximum particle size of 500'
It has been found that when temperatures above C are applied, thermally insulating molded bodies with good layer properties, especially good layer expansion properties, are obtained. This makes it possible to improve the expansion pressure of the obtained molded body and the erosion resistance of the molded body.

[Means for resolving curricular issues]

According to the invention, a thermally insulating molded body of the above-mentioned type comprises: 1. According to another preferred embodiment, the thermally insulating molded body according to the invention is characterized in that it contains unexpanded permiculite with a maximum particle size of 1.0 mm. Contains unexpanded permiculite with the largest particle size, but the 8% of permiculite contained in these compacts
0% has a particle size of up to 0.5 mm. This embodiment has the advantage that the erosion resistance can be further improved.

According to another preferred embodiment, the thermally insulating molded body according to the invention is provided in the above-mentioned 1. omm=, including crushed, unexpanded permiculite with a maximum particle size of at least 9.
5% has a particle size of up to 0.5m+m. This embodiment has the advantage that the structure of the molded body is significantly improved and its resistance to gas flow attack is further increased.

According to another preferred embodiment, the molded body according to the invention comprises:
crushed, non-expandable permiculite;
The ratio of unexpanded permiculite obtained by sieving to a particle size of up to 1.0++ no. is 30:70 to 70:30, even 40
:60 to 60:40. This embodiment has the advantage that a very uniform particle distribution is achieved, so that particularly good properties are obtained with respect to expansion pressure and erosion resistance.

The invention furthermore relates to a method for producing a thermally insulating molded body as described above, in which a fiber mat molded body is produced in a known manner from an aqueous suspension of initial materials, the method comprising: In the liquid, non-expandable permiculite, Narube (1
Use is made of unexpanded vermikinilite with a maximum grain size of . A cutting dispersion containing permiculite is used, of which at least 9
It is characterized in that 5% has a particle size of 0.5t+a and below.

According to another preferred embodiment of the method, the initial dispersion contains ground, unexpanded permiculite and up to 1.0111! A mixture of unexpanded permiculite obtained by sieving to a particle size of 1 is used, in this case a mixture of permiculite obtained by grinding and permiculite obtained by sieving. 30:70 to 70:
They exist in a ratio of 30.

To practice the invention, conventional refractory ceramic fibers are used. These ams can have a thickness of 1 to 101 m and a length of 1 to 10 m, and are usually
Such ceramic fibers can be heated, for example, at 1260°C or 1
It is defined by the classification temperature which can be 600°C.

The permiculite used according to the invention is a commercially available product. In order to obtain non-expandable permiculite with a maximum grain size of 0.1 mm, natural permiculite was processed into 1. It is possible to sieve to this particle size of 1.0 mm, but with sufficient grinding time it is also possible to grind natural permiculite which yields a product with a maximum particle size of 1.0 mm; The crushed permiculite can be sieved for safety and to remove particles with a particle size greater than 1.0 mm.

The organic polymeric fibrids used according to the invention are commercially available products that can be made from a variety of polymers.

Fibrids made of polyolefins, e.g. 125 to 1
Preferably, fibrids made of polyethylene with a softening point of 35°C or polypropylene with a softening point of 155 to 65°C are used.

The temporary or permanent binders used according to the invention correspond to the binders mentioned in German Patent Application No. 3,444,397.

The process for producing moldings according to the invention is carried out in a known manner, ie the starting materials are dispersed into a dispersion at a sufficient water level with a stirrer or with a suitable mixer. Subsequently, the fiber mat shaped body is transformed in a known manner, for example in a sieve mold or by settling out an aqueous suspension.

In these variants, shaped bodies in the form of mats of varying thickness are usually obtained, the thickness of which is dependent on and can be adjusted by the amount of dispersion that impinges on the sieve and is sucked up.

These shaped materials in the form of mats can be dried in a known manner, for example at temperatures up to 120°C. Subsequently, the transformation into the final shaped body can take place directly or by further processing, for which purpose such a mat is heated to a temperature at which the polymer of the fibrids is transformed, for example at about 135 °C.
When using polyethylene fibrids with a melting point of
Preferably, pearls are added. 160 or +8
Heating to an elevated temperature of 0'C - generally lasts for only a few minutes, for example from 3 to 20 minutes, depending on the thickness of the molding material, e.g. mat, to be deformed.

Depending on the content of fibrids in the molding, it is also possible to produce the molding from two parts of the molding stock, the contact surfaces of which are heated to an elevated temperature, e.g.
Welded together by pressure at 'c for 3 minutes at 80 pearls. In this embodiment, it is particularly preferred for the fipulid content to be set between 20 and 40%, based on the dried moldings.

In the case of complex shaped bodies, it is preferable to carry out cold quenching with the mold in contact with the shaped body, in order to avoid distortions of the final shaped body.

〔Example〕

The invention will be explained in detail with reference to the following examples.

Example 1 Unexpanded permiculite 3k obtained by sieving to a maximum particle size of 'Om hazy
thickness 1 to 3 with a classification temperature of 1260'C
14 kg of ceramic fibers with a μ field and a length of 1 to 5 mm were uniformly dispersed in 6001 water in a container by means of a stirring device. After adding 4.1 kg of a 3% dispersion of polyethylene fibrids with a melting temperature of about 135° C. and 300 g of an aqueous polyacrylate dispersion, the dispersion was coagulated by addition of a polyacrylamide solution. A fiber mat molding was produced by suctioning the water through a sieve and subsequent drying.

This molded body with a bulk density of approximately 900 kg/m3 was used as an insulating support layer or coating in thermal engineering devices and pipelines. After heat treatment, the molded bodies had excellent dimensional stability, being simultaneously strong and elastic, and were suitable for the installation and retention of ceramic catalysts and/or filters inserted into the pipelines. This molded body exhibited an expansion pressure of 0.6 N/+m2, which was measured by the following measuring method.

A square specimen is presented as a plate of uniform thickness. The load surface with a hole in the center can be used to accurately detect the specific expansion pressure (
m+n2) measured and placed under the pressure measuring device.

Before the first heating, a prepressure of 1 ON is applied over the entire surface.

Heating and cooling rates are approximately 10°C/min. For testing, 75°C to 750°C and back to 75°C.
The values listed in the cycle-operated 0 table are for the second cycle. This is because cycle 1 often shows abnormal values due to permiculite degassing.

The erosion values shown in Examples 2 to 4 in the table were determined by the following measurement method.

A sample with dimensions 60 x 15 x 5+++n is clamped so that the sprayed head area is approximately 75 mm2.

Before the experiment, the clamped samples are expanded by heat treatment to 750° C. (without any pull-hold time). The sample is then sprayed head-side with compressed air from a 15 mm diameter nozzle at 25 mm intervals. The compressed air is measured on the pressure side with a spacing of 14 m before the nozzle and
．． It is kept at the same level reaching 25 pearls. At various time intervals, the sample is weighted by a clamping device and any weight loss detected. The values listed in the table relate to a spraying time of 60 minutes.

Examples 2 to 4 The procedure of Example 1 was repeated, using the starting materials summarized in the following table. In this case, molded bodies were obtained exhibiting the properties summarized in the following table.

example

Claims (1)

Claims: 1. A refractory ceramic fiber characterized in that it comprises non-expandable permiculite with a maximum particle size of 1.0 mm and a ceramic fiber to permiculite ratio of 80. 20 to 30:70 permiculite, 5 to 40% by weight of organic polymer fibrids, based on the total composition, and a temporary and/or permanent binder. 2. Comprising unexpanded permiculite with a maximum particle size of 1.0 mm, at least 80% of which has a particle size of 0.5 mm and below. The thermally insulating fiber molded article described above. 3 Contains crushed, non-expandable permiculite, of which at least 95% is 0.5 m
characterized by having a particle size of m and below,
The thermally insulating fiber molded article according to claim 1 or 2. 4. The ratio of crushed unexpanded permiculite to unexpanded permiculite obtained by sieving to a particle size of 1.0 mm or less is 30:70 to 70. :30.
The thermally insulating fiber molded article described in . 5. Fiber mat moldings are produced from an aqueous suspension of the initial material in a known manner, characterized in that non-expandable permiculite with a maximum particle size of 0.1 mm is used as permiculite. from which a fiber mat is formed, which fiber mat is dried and optionally heat treated at a temperature sufficient to melt the organic fibrids and optionally thermally deformed, in which case the ceramic fibers are combined with the ceramic fibers. 5. A method for producing a thermally insulating fibrous molded body according to claim 1, wherein permiculite is used in a ratio of 80:20 to 30:70. 6. As permiculite, non-expandable permiculite is used with a maximum grain size of 1.0 mm, characterized in that at least 80% of it has a grain size of 0.5 mm and below, The method according to claim 5. 7. As permiculite, ground, unexpanded permiculite is used, at least 95% of which has a particle size of 0.5 mm and below. The method described in. 8 Permiculite obtained by sieving crushed, unexpanded permiculite to a particle size of 1.0 mm or less,
Ratio of non-expandable permiculite is 30:7
7. Process according to claim 5, characterized in that a mixture of 0 to 70:30 is used.