JPH10101440A - Fiber-reinforcing blow mix - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain staple usable instead of fiber glass, decomposable at a temperature lower than fiber glass and free from crack and shrinkage by forming of a solid content containing refractory aggregate and a specific thermosetting polymer fiber. SOLUTION: This blow mix comprises 100wt.% solid content of dried mix containing a refractory aggregate comprising dead-burnt magnesite, olivine, high-alumina aggregate, mulite, silicon carbide/graphite mixture, smokeless coal or mixture thereof at least in an amount of 95wt.% and containing about <=5wt.% additives such as dispersion and binder and flexible thermosetting aramid, polyamide or polyester fiber or staple (hereinafter collectively referred to as fiber) in an amount of 0.02-0.3wt.% based on 100wt.% solid content and capable of withstanding decomposition until about 204 deg.C (about 400 F) or mixture thereof and water capable of blowing in an amount of about 0.02-0.5 pts.wt. based on 100 pts.wt. solid content and requires length of fiber sufficient to prevent crack due to shrinkage during dryness of blown material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a fiber reinforced spray mix, sprayable compositions made therefrom and the resulting spray lining.

[0002]

BACKGROUND OF THE INVENTION Insulation boards, usually made of dead-burned magnesite bonded with resin, have been used for many years for lining tundishes. Such an insulation board facilitated the removal of skulls and gave the steel a clean surface. Over the past decade, spray mixes have replaced such insulation boards. Spray application is faster and requires less labor compared to insulating boards.

[0003] Refractory spray mixes have been commonly used to coat or form refractory linings on many metallurgical vessel surfaces, such as ladle and tundish. These coatings and linings provide thermal insulation that significantly reduces heat loss, and also after solidification of the solidified metal and / or
Or allow the slag skull to be removed to the container. Due to the relatively high insulation value of the spray lining, the skull is generally thinner and the relatively low strength of the coating allows for easy separation of the skull from the container lining.

[0004] Such mixes are sold in dry form, mixed with the liquid at the site to be applied, and sprayed to give the desired surface a refractory of the desired thickness. A typical spray-treated tundish lining is a water-based magnesite particle of dead-burned magnesite particles often mixed with low-cost refractory fillers, binders and reinforcing fibers.
It is applied in the form of a slurry. A sprayer is used to mix the powder with water and pump the resulting slurry through a hose and nozzle to a tundish. The slurry has the desired thickness, usually about 2.5-5.1 cm.
(Approximately 1-2 inches). The reinforcing fibers affect the rheology of the slurry and help prevent tundish wall collapse and droop. The reinforcing fibers also prevent shrinkage during drying and preliminary and cracking due to thermal stress.

It is known to dry such wet layers in several ways. One is commonly referred to as the "cold practice", which involves raising the temperature to about 538-760 ° C (about 1000-1 ° C).
Gradually raise to a temperature of 400 ° F), maintain that temperature until dry, and cool prior to use. Another method is the “hot tactic method”.
e)) at about 538-760 ° C. (about 1000-1
400 ° F.), cool, and then place the processed container at about 1204.5 ° C. (about 2200 ° C.) prior to use.
° F). Another "hot procedure" is about 120
Dry at 4.5 ° C. (approximately 2200 ° F.) for approximately 3 hours (the drying time depends on several factors, especially the thickness of the spray-coated coating), and then immediately put the hot container into service.

One of the problems with such blown mixes has been the tendency to shrink, crack and peel during drying and preheating. It is known to use fibers such as shredded paper or chopped fiberglass to prevent such cracking and provide reinforcement. However, paper alone has been found to be unsatisfactory because of the short cellulose fibers. It does not provide adequate reinforcement, cannot withstand the high temperatures encountered during drying and preheating, and therefore cannot help significantly reduce undesirable cracking effects. Poor heat resistance is also a problem with other organic fibers such as polyolefins, for example, polyethylene and polypropylene fibers. Another problem with spray mixes is whether the fibers are properly dispersed within the mix when dry mixed at the manufacturing plant prior to transport. Currently used organic fibers are matted in a dry mixing hopper, making it difficult to transfer the dry mix to a wet mixing device. With chopped fiberglass, this is not only an expensive material, but there is some concern about its potential health effects.

[0007]

The present invention can be used in place of fiberglass, which can be decomposed at lower temperatures than fiberglass, but reduces the undesirable cracking and shrinkage of the spray coating during drying. It overcomes the problems of the prior art by using fibers or staples that can be satisfactorily prevented. Here "staples"
The term refers to relatively short lengths of textile fibers.

[0008]

SUMMARY OF THE INVENTION Briefly, the present invention provides a 100% by weight solids containing refractory aggregate, and about 0.02 to 0.3% by weight per 100% by weight of the solids. A powdered fiber reinforced spray mix comprising flexible thermoset polymer fibers that resists decomposition at temperatures up to about 204.5 ° C. (about 400 ° F.).

The present invention also provides sprayable compositions made from such powder mixes, and linings obtained therefrom.

It is a feature of the present invention to provide a spray mix in which fiberglass is omitted and instead some organic fibers are used.

Another general object of the present invention is to provide fibers or staples (preferably having a melting point above 400 ° F., ie, about 204.5 ° C.) made from aramid, polyester, polyamide or mixtures thereof. Is to use.

It is a further object of the present invention to provide a desirable dispersion without mixing the fibers in a drying hopper when mixed with other dry ingredients.

In the present invention, apart from the fibers, there is no particular requirement on the refractory aggregate used or on the other components normally added to form such a spray mix. That is, any suitable aggregate for spraying can be used, and although dead burned magnesite is preferred, other olivine, refractory clay, high alumina aggregate, mullite, silicon carbide / graphite mixtures, Anthracite and mixtures thereof can also be used.
The amount of aggregate added is a conventional amount used to provide thermal insulation and other desired properties and may vary depending on the needs of the particular metallurgical vessel to which the spray coating is applied. The refractory aggregate makes up at least 90% by weight of the dry mix, preferably at least 95%.

Furthermore, as is known, dispersants, binders,
Additives such as plasticizers and density reducers may be added to the mix in conventional amounts for their intended purpose, as is conventional. Such additives typically make up to at most about 5% by weight of the mix. Mixes containing dead-burned magnesite and such additives are trademarks "DO"
SSOLITTE ".

An important feature of the present invention is that flexible thermoset aramid, polyamide or polyester fibers or staples (collectively referred to herein as "fibers"), or a mixture thereof, may be used with other sprays. It is used for various components of the mix. As used herein, the term "polyamide" refers to a synthetic polyamide rather than a natural polyamide, and such composites are most typically nylons and "Versamid's".
s ", the latter being a reactive polyamide, usually copolymerized with an epoxy resin. Aramids are another class of highly aromatic polyamide fibers that are characterized by their flame retardancy and are commonly used in protective garments, tire cords, and the like. It is important to use one with a melting point as high as possible, preferably above about 400 ° F. (204.5 ° C.).

It is preferred to use thermosetting flexible polyester fibers, especially those which comprise at least 85% by weight of an ester of a dihydric alcohol and terephthalic acid. Such a material is heated to about 204.5 ° C. (about 400 ° C.).
It can withstand decomposition at higher temperatures than F). Alkyd resins, allyl resins, which can be formed into fibers having a decomposition temperature greater than about 204.5 ° C. (about 400 ° F.);
Other thermosetting resin fibers made from amino resins, epoxy resins, phenolic resins and urethane resins can also be used. As is well known to those skilled in the art, there are materials that can be copolymerized with these resins to improve their resistance to degradation at temperatures below about 400 ° F. (about 204.5 ° C.).

To prevent the problem of fibers and staples forming mats in the drying hopper, a length of about 1
2.7 mm (about 1/2 inch) or less, preferably 2.5 mm
Although preferred because it is .about.7.6 mm (0.1-0.3 inches), this is not required.

The denier value of the fibers is not critical and may be any conventionally available denier value, suitably about 1-2 denier per fiber, preferably 1.5 denier.

If desired, other organic fibers, such as cellulose in the form of fibers or chopped paper, may be included, for example, with polyester fibers.

The only requirement is that the fibers be long enough to reinforce and toughen the refractory to prevent cracking due to shrinkage of the spray during drying.

For the amount of fiber used, about 0.0
From 2 to 0.50 parts by weight of fiber may be used per 100 parts by weight of other solids, but it is preferred to use no more than about 0.075 parts by weight.

The fibers are simply mixed with the other ingredients of the mix, but if more than about 0.075 parts by weight (per 100 parts by weight solids) are used, the fibers are mixed so that matting does not occur. Caution should be exercised when

The dry mix is made into a sprayable mix by conventional means, ie by adding water at the time of application. The amount of water added is sufficient to form a composition that can be sprayed using a conventional refractory sprayer. The amount of water in each case will mainly depend on the composition of the particular mix, but the optimal amount of water can be determined by routine experimentation.

Although these fibers have a much lower melting point than fiberglass (fiberglass),
It has been unexpectedly found that the spray lining can be satisfactorily reinforced at the temperatures used during drying and temperature-up heating.

The present invention is further described by the following examples, which are intended to be illustrative and illustrative.
It does not limit the invention.

Examples 1-4 A series of spray mixes having the formulations shown in Table 1 below were prepared and tested. The proportions of the components are% by weight. The mix of Example 4 is a commercial product "Dossolite" sold by Daussanet Compagnie Metallurgical Research Laboratories, France.
1400-72 "(trademark).

The mixes were sprayed at the same mixing and spraying speed with a portable sprayer, and the disperser and sprayability were recorded. Table 2 shows the results of these tests.

[0028]

[Table 1] 1 2 3 4 Mix Deadly burned magnesite 67.9% 68.2 68.225 67.9 Olivine 27.5 27.5 27.5 27.5 Additives 4.1 4.1 4.2 4.1 Polyester fiber * 0.5 0.2 0.075-Fiber glass---0.5 * DuPont "Dacron" polyester fiber type 257W, 6mm

[0029]

[Table 2] 1 2 3 4 sprayer Reinguss PDSM water g / m - 1.2 1.2 1.4 Bulk density g / m ³ (3 Mean) - 1.792 1.744 1.744

Spraying properties: The mix of Example 1 was not sprayed because its polyester fiber content was too high to handle properly and spraying was not possible. The mixes of Examples 2, 3 and 4 sprayed well.

The mix of Example 2 showed many lumps in the slurry, but the lumps were not hard but were aggregates of fines. The mixture of Example 4 has few lumps and
Showed a smoother spray surface than that of

Practical experiments in a commercial metallurgical vessel showed that the spray mix containing both the fiberglass and shredded paper of Example 4 was slightly better than that of Example 3.

Although the present invention has been described in terms of several preferred embodiments, there is no intention to limit the scope of the invention to those particular ones, and the invention is not limited to the spirit and scope of the invention. , Modifications and equivalents.

Continuation of front page (71) Applicant 596031491 2121 San Jacinto Street, Suite 2500, Dallas, Texas 75201, United States of America

Claims (12)

[Claims] 1. A solid content of 100% by weight including refractory aggregate, and about 0.02 to 0.2% by weight per 100% by weight of the solid content.
A powdered fiber-reinforced spray mix comprising 3% by weight of flexible thermoset polymer fibers that resist degradation at temperatures up to about 400 ° F. (about 400 ° F.). 2. The refractory aggregate is dead burned magnesite, olivine, high alumina aggregate, mullite, a silicon carbide / graphite mixture, anthracite or a mixture thereof, and the polymer fibers are thermoset aramid, polyamide or polyester. The spray mix of claim 1 which is a fiber. 3. The spray mix of claim 2 wherein the refractory aggregate is a mixture of dead-burned magnesite and olivine and the polymer fibers are polyester. 4. A polyester fiber having a length of about 2.54 to
About 0.1-0.3 inch (7.62 mm), about 1-2 denier per fiber, and an amount of fiber of about 0.0
The spray mix of claim 4 wherein the amount is 2 to 0.075% by weight. 5. A solid content of 100% by weight including refractory aggregate, and about 0.02 to 0.1% by weight per 100% by weight of the solid content.
Fiber reinforcement comprising 3% by weight of a flexible thermoset polymer fiber that resists decomposition at temperatures up to about 400 ° F. (about 400 ° F.) and water in an amount sufficient to make the composition sprayable. Sprayable composition. 6. The refractory aggregate is dead burned magnesite, olivine, high alumina aggregate, mullite, a silicon carbide / graphite mixture, anthracite or a mixture thereof, and the polymer fibers are thermoset aramid, polyamide or polyester. The sprayable composition of claim 5, which is a fiber. 7. The sprayable composition of claim 6, wherein the refractory aggregate is a mixture of dead-burned magnesite and olivine and the polymer fibers are polyester. 8. The polyester fiber having a length of about 2.54 to
7.62 mm, about 1-2 denier per fiber,
The sprayable composition of claim 7, wherein the amount of fiber is from about 0.02 to 0.075% by weight. 9. A spray lining for a metallurgical vessel which comprises a lining formed by spraying the composition of claim 5 onto the surface of the metallurgical vessel, and which resists cracking and peeling during drying and preheating. 10. The refractory aggregate is dead burned magnesite, olivine, high alumina aggregate, mullite, a silicon carbide / graphite mixture, anthracite or a mixture thereof,
10. The spray lining of claim 9 wherein the polymer fibers are thermoset aramid, polyamide or polyester fibers. 11. The spray lining of claim 10 wherein the refractory aggregate is a mixture of dead-burned magnesite and olivine and the polymer fibers are polyester. 12. The polyester fiber having a length of about 2.54 to
7.62 mm, about 1-2 denier per fiber,
The spray lining of claim 11, wherein the amount of fiber is about 0.02-0.075% by weight.