TWI476309B - Flame-resistant cellulose fibre, its use and production process - Google Patents

Description

Fire-resistant cellulose fiber, use thereof and method of manufacture

This invention relates to a fire resistant cellulosic recycled fiber having improved usability characteristics for use in textile applications (e.g., meeting the requirements of industrial dry cleaning), its use in the manufacture of yarns and fabrics, and methods of making such fibers.

First, fiber systems based on the mucus method are known as regenerated fibers, and they are made in the world with individual fiber deniers between 0.8 and 16 dtex for textiles and non-wovens. Standard application of the weaving department. Different chemicals are disclosed in the literature on the post-fire treatment of mucinous fibers. In this regard, the use of fire retardants is based on halogens, bismuth and phosphorus.

For this application, U.S. Patent No. 2,678,330 discloses the use of bis(2,3-dichloropropyl) chlorophosphonate. The use of tris(1-bromo-2-chloro-2-propyl)phosphate is mentioned in the publication GB1158231. Patent FR 2 138 400 discloses the use of liquid polybromobenzene and particularly preferably hexabromobenzene. Since the liquid fire-resistant agent is only embedded in the structure of the fiber, it is impossible to establish a covalent bond with the cellulose component. These chemicals move much more in the fiber than solids. Most importantly, the fire resistance of the fibers after repeated drying at elevated temperatures (i.e., in a tunnel dryer) will be significantly reduced.

Similarly, Soviet Patent No. SU 661 047 discloses the use of halogenated compounds such as hexachlorocyclohexane, halogenated benzene and tris(dibromopropyl)phosphate. In recent years, the use of halogen-containing fire retardants has been greatly reduced due to ecological considerations, and they are not representative of supporting solutions for future development. For example, tris(dibromo-propyl)phosphate is Oeko-Tex The community group is listed as a prohibited fire retardant.

For example, the refractory effect is based on the use of phthalate-based mucoid fibers disclosed in patents WO9313249 and CN1847476. These mucoid fibers are ecologically sound, but the related mechanical fiber properties and washability are not in line with the modern textile industry. Demand. According to today's knowledge hierarchy, only phosphorus-containing and halogen-free fully water-insoluble solid fire retardants meet all requirements in terms of ecology, fire behavior, textile data and other usability characteristics.

Patent EP 0 863 634 discloses a fire-resistant regenerated fiber produced according to the Lyocell process, which theoretically achieves the above requirements. However, the phosphorus compound used is not likely to be produced on a large scale because the production cost is too expensive, so that the fiber does not represent an alternative in practical conditions.

Fire-resistant slime fibers produced by the incorporation of phosphorus-containing pigments in the standard mucus process are also disclosed in Chinese Patent Nos. CN 101215726, CN 101037812 and CN 1904156. However, the fibers disclosed in these patents are unable to meet the high demands of the modern textile industry, and their customized products will be shown below on a trial basis (Table 1).

Patent DE 4128638 A1 or DE 102004059221 A1 discloses 2,2'-oxybis[5,5-dimethyl-1,3,2-dioxophosphate 2,2'-disulfide-based and refractory dispersion media using different dispersion media systems, and these patents also mention the use of these dispersion media for the fire resistance post-treatment of slime fibers.

Similarly, EP 1882760 discloses the use of 2,2'-oxybis[5,5-dimethyl-1,3,2-diphosphine. A 2,2'-disulfide-based fire-retardant dispersion medium for the manufacture of fire-resistant slime fibers. In essence, a particle size equal to 10 micrometers (μm) maximum is described as the most important feature of the invention, so the spinning agglomerates must be cleaned prior to spinning through a filter having a maximum aperture width of 10 microns. However, it can be seen that this criterion is not sufficient to produce fibers that meet the above requirements. The maximum particle size of 10 microns as described in EP 1882760 may be sufficient for mucous monofilaments (i.e., toroidal monofilaments), but in any respect does not meet the requirements for modern staple fiber manufacture of about 1 to 4 cents; The fractional fiber has a diameter of about 10 microns.

Today, a wide range of standard slime fibers are used in lightweight fashion textiles. However, first in the wet regulations, low toughness, high elongation and high area shrinkage will limit the use of slime fibers. For example, these textile properties are not allowed to be used in blocks where frequent washing of textiles, particularly industrial laundry, is required. For example, the measure of washability is the area shrinkage. In order to be able to easily record the area shrinkage rate in quantitative terms, the correlation with the wet modulus measured according to the BISFA rule (hereinafter simply referred to as "BISFA wet modulus") is used (BISFA, testing methods viscose, Modal). , Lyocell and acetate staple fibres and tows, 2004 Edition).

For mucofibers, the relationship between area shrinkage (after washing) and BISFA wet modulus has been known since the 1970s (Szeg , L., Fiber Research, Text. Techn.; 21 (10), 1970). When the BISFA wet modulus is 2, we can assume that the wash shrinkage is 15-20%, and when the BISFA wet modulus is 5, the shrinkage has dropped to 4-7% (see Figure 1).

Fibers described and/or commercialized in the art are manufactured by standard mucus processes. They show good mechanical fiber data compared to fire resistant mucilage fibers because the phosphorus content is very low. However, tests on various fire retardant-based fire retardants have shown that sufficient refractory effects can be achieved at phosphorus levels greater than 2.8%. Fire resistance is highly correlated with the amount of fire retardant that can be converted to pure phosphorus.

However, it can be ascertained that the incorporation of a large amount (15-25%) of the refractory pigment causes the textile parameters of the slime fiber to deteriorate. For this reason, the application limitations already mentioned for standard mucus fibers are more suitable for fire resistant mucilage fibers.

This is a pity, as refractory fibers can be used particularly advantageously in products that are exposed to strong mechanical loads, such as professional clothing for special hazardous activities in fire brigades, foundry, military, and oil chemical industries. With regard to such products, synthetic high performance fibers such as (aromatic) polyamines, linaloamines, polyimines and the like are generally used. However, these fibers have very low wearing comfort because they do not absorb moisture efficiently. Therefore, blends of these fibers with cellulosic fibers would be desirable, with cellulosic fibers increasing a range of wearing comfort, but would otherwise not significantly deteriorate other characteristics.

In summary, the prior art only revealed that fire-resistant fibers made from ecologically harmful chemicals do not have sufficient toughness, BISFA wet modulus and textile usability characteristics, and cannot be used for textile purposes or because of their production mode. Mass production. In fact, some announcements have revealed that it is not desirable to manufacture fire resistant cellulosic fibers other than the editor's intention.

task:

In contrast to the prior art, this task is to produce a usable fire resistant cellulosic fiber that meets the requirements of today's economically and ecologically responsible manufacturing processes and higher textile machinery requirements, such as industrial dry cleaning. Made of clothing goods.

The requirements for refractory fibers for modern textile applications can be described in practical terms as the product of the phosphorus content (which is the ability to perform fire resistance) and the wet modulus (associated with the area shrinkage) measured according to the BISFA rules. Therefore, the product of the phosphorus content and the BISFA wet modulus will be designated as "usage value" hereinafter.

In addition, this task also involves performing a suitable manufacturing process that can be used for these fibers.

Surprisingly, this task can be solved by a refractory regenerated cellulose fiber for textile applications comprising a granulated phosphorus compound incorporated as a refractory material, preferably an organophosphorus compound, And the fiber has a usability value between 6 and 35, preferably between 8 and 35 and most preferably between 10 and 35. It is feasible to manufacture such fibers in the first place by the mucus method modified according to the invention.

The refractory material preferably has a particle size distribution with an X ₅₀ value of less than 1.0 μm and an X ₉₉ value of less than 5.0 μm.

Preferably, 2,2'-oxybis[5,5-dimethyl-1,3,2-dioxophosphate is used. 2,2'-disulfide (formula I) as an organophosphorus compound. A sufficient amount of this material is available under the trade names Exolit® and Sandoflam® and will not be washed out from the manufacturing process at a later application.

The fibers according to the invention comprise at least 2.8% phosphorus, based on cellulose, in the preferred embodiment of the invention between 3.2% and 6.0%, most preferably between 3.5% and 6.0%. A low phosphorus content of less than 2.8% does not produce sufficient fire resistance. A high phosphorus content of more than 6% reduces the mechanical properties of the fiber and is therefore no longer economical.

The fire-resistant fiber according to the present invention is particularly suitable, which has a BISFA wet modulus (B _m ) of greater than or equal to 0.5‧(√ T)‧10/T and an elongation of 5% under wet conditions. Here, T is the denier of each fiber and is represented by dtex; B _{m is} represented by cN/tex. The refractory fibers according to the invention are preferably in the form of short fibers, i.e., the fibers are cut to a uniform length during the manufacturing process. The staple length of staple fibers in the textile field is between 20 and 150 mm. Only uniform lengths of all of these fibers allow for problem-free processing with high productivity on machines currently used in textile chains.

The subject of the invention also relates to the use of the fibres according to the invention for the manufacture of yarns. Such yarns are characterized by a higher strength than the fiber strands currently used. In order to be able to show the appropriate properties of the respective application, in addition to the fibers according to the invention, such yarns according to the invention may also comprise fibers of another source, such as wool, fire resistant wool, para and ortho-arylamines. , polybenzimidazole (PBI), o-phenyl-2,6-benzobisoxazole (PBO), polyimine (P84 ), polyamine-quinone imine (Kermel) Modified Polyacrylonitrile, Polyamide, Fire Resin Polyamide, Fire Resistant Acrylic Fiber, Melamine Fiber, Polyester, Fire Resistant Polyester, Polyphenylene Sulfide (PPS), Polytetrafluoroethylene (PTFE) , glass fiber, cotton, silk, carbon fiber, oxidative heat stable polyacrylonitrile fiber (PANOX And conductive fibers and blends of these fibers.

Likewise, the use of fibers according to the present invention in the manufacture of fabrics is also the subject of the present invention. In addition to the fibers according to the invention, the fabric also comprises other fibers, such as, for example, wool, fire resistant wool, para and ortho-arylamine, polybenzimidazole (PBI), o-phenyl-2, 6-benzobisoxazole (PBO), polyimine (P84 ), polyamine-quinone imine (Kermel) Modified Polyacrylonitrile, Polyamide, Fire Resin Polyamide, Fire Resistant Acrylic Fiber, Melamine Fiber, Polyester, Fire Resistant Polyester, Polyphenylene Sulfide (PPS), Polytetrafluoroethylene (PTFE) , glass fiber, cotton, silk, carbon fiber, oxidative heat stable polyacrylonitrile fiber (PANOX And conductive fibers and blends of these fibers.

The fabric is preferably a woven fabric, a knitted hosiery fabric, a knit fabric, but may also be a non-woven fabric. Similarly, for high quality non-woven fabrics, it is critical to use fibers having a high BISFA wet modulus and high strength. In the case of woven or knitted fabrics, the blend of fibers according to the invention with other fibers can be blended prior to yarn manufacture (so-called intimate blends), or during weaving, warping or knitting. Pure yarns of these different fiber forms are used in combination in each case.

The fibers according to the present invention can be made by the mucus method according to the present invention, and the modification of the slimming method is also the subject of the present invention. In principle, the mucus method for short fibers and ring-shaped single fibers has been known for many years. For example, this mucus method is described in detail in K. G. Tze, Chemiefasern nach dem Viskosefasern, 1967. However, the textile properties of the fibers and monofilaments obtained from this process are considerably affected by many parameters. In addition, due to the design of existing manufacturing units, there are restrictions on many influential variables (which may be for technical and economic reasons), so the authority cannot be exceeded, so that changes in various parameters are often not feasible, even Professionals have not provided this to solve this problem.

It can be seen that with regard to the production of the fiber according to the present invention, when a slurry having an R-18 content of 93 to 98% and a base ratio (cellulose concentration/sodium hydroxide concentration, usually gram/liter) of 0.7 to 1.5 is used, At the time, the cellulose concentration will be ideal at 4-7%. However, the spinning parameters must be modified as a result of the addition of the fire resistant FR pigment.

Therefore, the subject matter of the present invention is also directed to a method of making fire resistant regenerated cellulosic fibers for textile applications by having 4 to 7% cellulose, 5 to 10% NaOH, 36 to 42% (by Cellulose, carbon disulfide and 1 to 5% (by cellulosic) of the content of the modifier are spun into a spinning bath, and the condensed filaments are drawn to produce a spinning gamma value of the mucus used. 50 to 68 (preferably 55 to 58) and having a spinning viscosity equal to 50 to 120 ball drop seconds; and the temperature of the spinning bath is equal to 34 to 48 ° C, whereby

a) the alkali ratio (=cellulose concentration/base content) of the mucilage ready for spinning is equal to 0.7 to 1.5,

b) Use the following spinning bath concentrations:

H ₂ SO ₄ 68-90 g / liter

Na ₂ SO ₄ 90-160 g / liter

ZnSO ₄ 30-65 g / liter

c) the final withdrawal of the spinning bath is carried out at a speed of 15 to 60 meters per minute, and

d) Incorporation of a pigment-formed organophosphorus compound in the form of a pigment dispersion as a refractory substance during spinning.

More importantly, the viscosity is applied to the mucus before spinning to use the mucus.

The measurement according to the present invention adheres to a certain degree of spinning maturity, wherein the spinning gamma value can be characterized by adhering to a certain viscosity, and the ball falling value can be characterized by adhering to the conditions of a certain spinning bath, which in general can lead to the required requirements. Fiber properties. The distribution of the binding of the carbon disulfide molecules to the 100 cellulose molecules is clarified by the spinning gamma value. The spinning gamma value is measured according to Zellchemig-data sheet draft of R. Stahn [19580 respectively sheet III/F 2 . The ball drop value represents the viscosity measured according to the ball drop method; this is expressed in seconds of the ball drop. This definition is made by K. G. Tze, Chemiefasern [1951], p. 175.

The refractory phosphorus compound which is made into a pigment is added to the mucilage spinning solution in the form of a pigment dispersion. In this aspect, sufficient of the refractory material is incorporated such that the finished fiber contains at least 2.6%, preferably between 3.2% and 6.0%, optimally between 3.5% and 6.0%, based on the cellulose. Between the phosphorus.

As indicated above, a particularly suitable fire-resistant organophosphorus compound is 2,2'-oxybis[5,5-dimethyl-1,3,2-dioxophosphate for the purposes of the present invention. ] 2, 2'-disulfide.

In particular, the quality of the pigment dispersion has a considerable influence on the fiber properties. This can be determined by the average particle size and maximum of the pigment, the concentration of the dispersion used (i.e., when added to the mucilage solution), and the form and amount of the dispersant.

10 micron particle size compared to the upper limit of the disclosed No. 1882760 EP, it is found in an average particle size (X ₅₀₎ and a maximum value of less than 1 micron particle size (X ₉₉₎ of less than 5 microns is required. Figure 2 shows the size distribution of a still suitable pigment dispersion.

Preferably, the pigment dispersion should contain from 10 to 50% of a fire resistant material.

In many of the literature on prior art, the effects of the dispersant are not properly specified. However, many chemicals that provide excellent stable refractory pigment dispersions still have a negative effect on the spinning process, as these chemicals can cause modification of the slime filaments when compared to the modifier used. And there is no positive effect on fiber toughness. For the refractory pigment dispersion used to make the fiber according to the invention, the pigment dispersion which proves to be the best and has no adverse effect on the fiber strength comprises the following group: a modified polycarboxylate, Water-soluble polyester, alkyl ether phosphate, blocked ethoxylated phenol, castor oil alkoxy ester and carboxymethylated alcohol polyglycol ether. Preferably, the pigment dispersion should contain from 1.5 to 13% of a dispersant.

The invention will be illustrated by way of example. It is to be understood that these embodiments are illustrative of specific embodiments of the invention. The invention is in no way limited to the scope of the embodiments.

Example: Example 1:

6 parts by weight of 2,2'-oxybis[5,5-dimethyl-1,3,2-diphosphine by means of a dissolver ] 2,2'-disulfide, 6 parts by weight of water and 0.55 parts by weight of alkyl polyglycol ether-phosphate homogenized and in a ball mill (Drais, type Perl Moll PML-V/H) and 40-55 The object was ground using a zirconia abrasive at a temperature of ° C until the finished dispersion showed X ₉₉ <1.5 μm.

The beech wood pulp (R18 = 97.5%) was alkalized at 35 ° C with an alkali solution containing 240 g / liter of NaOH and pressed into an alkali cellulose-like wool. The alkaline cellulose-like wool is decomposed, matured and reacted with CS ₂ to form a flavo benate. The xanthate was dissolved in diluted soda hydrate to obtain a mucilage containing 5.6% cellulose, 6.8% NaOH, and 39% CS ₂ as cellulose. This mucus was filtered 4 times and the air was removed. One hour before spinning, 3% (by cellulose) of the ethoxylated amine which induces the core sheath structure was added to the mucus. The mucilage was cooked to a spinning γ value of 57. The viscosity during spinning is equal to 80 balls per second. The completed fire resistant dispersion is added to the slime immediately prior to spinning. The nozzle used showed an injection hole diameter of 60 microns. The spinning bath contained 72 grams per liter of sulfuric acid, 120 grams per liter of sodium sulfate, and 60 grams per liter of zinc sulfate.

The temperature of the spinning bath was equal to 38 °C. The condensed and partially regenerated pale yellow plastic filament fiber bundle is introduced into the second bath at a temperature of 95 ° C via a godet (G1), wherein the fiber bundle is at G1 and the second godet (G2) The length is extended by 120%. The final extraction speed is equal to 42 meters per minute. Cut the cellulose into short fibers of 40 mm length, completely regenerate the short fibers in diluted sulfuric acid, then wash them with hot water until no acid, desulfurize with soda lye, and wash again to dilute The sodium hypochlorite solution is bleached, washed again, finished, pressed and dried.

Example 2:

6 parts by weight of 2,2'-oxybis[5,5-dimethyl-1,3,2-dioxophosphate, similar to the method of Example 1. 2,2'-disulfide, 6 parts by weight of water and 0.63 parts by weight of carboxymethylated alcohol polyglycol ether were treated to prepare a slime for spinning (composition: cellulose 5.9%, NaOH 6.7%, CS ₂ was 41% based on cellulose, and ethoxylated amine was 3.5% based on cellulose, and was spun into an aqueous spinning bath. The nozzle used showed the orifice diameter of the spinneret to be 50 microns. The spinning bath contained 74 grams per liter of sulfuric acid, 132 grams per liter of sodium sulfate, and 65 grams per liter of zinc sulfate.

Example 3:

6 parts by weight of 2,2'-oxybis[5,5-dimethyl-1,3,2-dioxophosphate, similar to the method of Example 1. 2,2'-disulfide, 6 parts by weight of water and 1.1 parts by weight of ethylated decanoic acid were treated to prepare a slime for spinning (composition: cellulose 5.8%, NaOH 6.5%, CS ₂ with cellulose) Calculated as 40%, a blend of 2% DMA + 1% PEG 2000 was used as a modifier (usually based on cellulose) and spun into an aqueous spinning bath.

The nozzle used showed a nozzle diameter of 50 microns. The spinning bath contained 73 grams per liter of sulfuric acid, 120 grams per liter of sodium sulfate, and 58 grams per liter of zinc sulfate.

Example 4 (Comparative Example):

Fibers are made according to the teachings of CN101037812. Since there is no indication of the amount of wet modulus in this publication, the conditions of the examples having the highest wet strength (Example 2, 1.52 cN/tex) were selected, and the following process conditions were set accordingly: 8.86% of cellulose, NaOH 6.24%, CS ₂ is 31% based on cellulose. No modifiers were added. This mucus is spun at a viscosity of 42 balls per second.

The high phosphorus content indicated in this announcement cannot be tested. In order to obtain acceptable strength, several optimized tests were carried out with different levels of fire retardant under specified regulations. The specified characteristics are only achievable when the phosphorus (P) content is reduced to 2.1% by weight based on cellulose.

The nozzle used showed a nozzle hole diameter of 60 microns. The spinning bath contained 115 grams per liter of sulfuric acid, 330 grams per liter of sodium sulfate, and 45 grams per liter of zinc sulfate.

Example 5 (Comparative Example):

The fiber is manufactured according to CN1904156, so the specific recommended process conditions are set as follows: cellulose 8.9%, NaOH 5.2%, and CS ₂ is 33% in terms of cellulose. No modifiers were added. This slime is spun at a viscosity of 55 balls per second.

Similarly, the high phosphorus content shown in this announcement cannot be tested. In order to achieve acceptable toughness, several optimized tests were carried out with different levels of fire retardant under specified regulations. Also, in this embodiment, it is possible to achieve the specified characteristics when the phosphorus content is reduced to 2.1% by weight based on the cellulose.

The nozzle used showed a nozzle hole diameter of 60 microns. The spinning bath contained 115 grams per liter of sulfuric acid, 350 grams per liter of sodium sulfate, and 11 grams per liter of zinc sulfate. The temperature of the spinning bath was equal to 49 °C.

A comparison of these fiber characteristics shows very clearly that the fire resistant mucilage fibers produced according to standard adhesive conditions as in Examples 4 and/or 5 clearly have a lower usability value than those produced in accordance with the present invention.

Figure 1 shows the relationship between area shrinkage and BISFA modulus.

FIG 2 having a display size X ₅₀ = 0.92 X ₉₉ = 3.55 microns and still fit microns distribution of the pigment dispersion.

Claims (19)

A fire-resistant regenerated cellulose fiber for textile applications, characterized in that the fiber comprises a granulated phosphorus compound incorporated as a refractory substance, and the granulated phosphorus compound is incorporated in the form of a refractory pigment dispersion, and The fiber shows a value of usage between 6 and 35. A fire-resistant regenerated cellulose fiber according to claim 1 of the patent application, which exhibits a value of use between 8 and 35. A fire-resistant regenerated cellulose fiber according to claim 1 of the patent application, which exhibits a value of use between 10 and 35. A fire-resistant regenerated cellulose fiber according to claim 1 which comprises at least 2.8% phosphorus by weight of cellulose. A fire-resistant regenerated cellulose fiber according to claim 4, which comprises between 3.2% and 6.0% phosphorus in terms of cellulose. A fire-resistant regenerated cellulose fiber according to claim 4, which comprises between 3.5% and 6.0% phosphorus on a cellulose basis. The fire-resistant regenerated cellulose fiber according to claim 1, wherein the phosphorus compound is 2,2'-oxybis[5,5-dimethyl-1,3,2-diphosphine ] 2, 2'-disulfide. A fire-resistant regenerated cellulose fiber according to claim 1 which has a BISFA wet modulus (B _m ) ≧ 0.5‧(√ T) ‧10/T and an elongation of 5% under wet conditions, wherein T is The denier of each fiber, expressed in dtex. A fire-resistant regenerated cellulose fiber according to claim 1, wherein the refractory substance has a particle size distribution with an X _{50 of} less than 1.0 μm and an X _{99 of} less than 5.0 μm. The fire-resistant regenerated cellulose fiber of claim 1, wherein the fire-resistant dispersion comprises a dispersant selected from the group consisting of modified polycarboxylates, water-soluble polyesters, alkyl ether phosphates , blocked ethoxylated phenol, ricinus oil alkoxy ester and carboxymethylated alcohol polyglycol ether. A use of a fiber as claimed in claims 1 to 10 for the manufacture of a yarn. A use of a fiber as claimed in claims 1 to 10 for the manufacture of a fabric. A method of making fire-resistant regenerated cellulose fibers for textile applications by having 4 to 7% cellulose, 5 to 10% NaOH, 36 to 42% (by cellulose), and 1 to The 5% (by cellulosic) modification of the contents of the mucilage is spun into a spinning bath, and the condensed filaments are drawn out, wherein the γ value of the mucilage used is equal to 50 to 68 and the spinning viscosity is equal to 50 to 120 balls falling seconds; and the temperature of the spinning bath is equal to 34 to 48 ° C, the method is characterized in that a) the alkali ratio (= cellulose concentration / alkali content) of the mucus prepared for spinning is equal to 0.7 to 1.5, b) using the following spinning bath concentrations: H ₂ SO ₄ 68-90 g / liter Na ₂ SO ₄ 90-160 g / liter ZnSO ₄ 30-65 g / liter c) The final of the spinning bath The extraction is carried out at a speed of 15 to 60 meters per minute, and d) a particulate phosphorus compound in the form of a pigment dispersion is incorporated as a refractory substance during spinning. The method of claim 13, wherein the refractory material is incorporated in an amount sufficient to provide the finished fiber at least 2.8% by weight of the cellulose. The method of claim 14, wherein the finished fiber contains between 3.2% and 6.0% phosphorus by weight of the cellulose. The method of claim 14, wherein the finished fiber contains between 3.5% and 6.0% phosphorus by weight of the cellulose. The method of claim 13, wherein the organophosphorus compound is 2,2'-oxybis[5,5-dimethyl-1,3,2-dioxophosphate ] 2, 2'-disulfide. The method of claim 13, wherein the pigment dispersion comprises 10 to 50% of the refractory material having an average particle size (X ₉₀ ) of less than 1.0 μm and a maximum particle size (X ₉₉ ) of less than 5.0 μm and 1.5 to 20%. Dispersing agent. The method of claim 18, wherein a dispersant selected from the group consisting of a polysulfide dispersion, a water-soluble polyester, an alkyl ether phosphate, and a sealant is used. The end of the ethoxylated phenol, castor oil alkoxy ester and carboxymethylated alcohol polyglycol ether.