FI64664B - FREEZING FABRICS FOR EXPLOITATION OF METALOXIDACYLAT BEHANDLADE FIBER - Google Patents

Description

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Patents and Refunds 7 Amttkan utlagd och utUkrtften puWIcersd 31.08.63 (32) (33) (31) Pyr <i * «r privilege —Begird prlorttet 01.12-78 Denmark-Danmark (l) K) 5 ^ 78/78 (71 ) Kjeld Holbek ApS, Lejrevej 7 * + »DK-1320 Lejre, Denmark-Danmark (DK) (72) Kjeld Holbek, Lejre, Denmark-Danmark (l) K) (jk) Berggren Oy Ab (5 * 0 Method for essentially separate The present invention relates to a process for the preparation of substantially separate metal oxide acylate-treated fibers for the production of substantially separate metal oxide diacylate-treated fibers.

FI patent application No. 781,770 describes a process for impregnating cellulose fibers and the areas of application of the fibers thus treated, in particular the use of fibers as reinforcing fiber parts in composite materials based on organic or inorganic binders or combinations of organic and inorganic binders.

One of the categories of treatment and impregnating agents mentioned in the above-mentioned patent application has been found to have particularly valuable properties, since in the treatment performed with these the properties of both cellulosic fibers and other fibrous substances can be improved in the expected and particularly desirable manner. These fibers, the properties of which can be modified as desired by treatment with metal oxide acylates, are any cellulose fibers, animal fibers and man-made fibers of both inorganic and organic origin, including metallic fibers.

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These fibers are essentially separate fibers.

The main groups of fibers which can be advantageously treated with metal oxide acylates according to the invention are: 1. cellulose-based materials: finely divided wood such as wood wool, wood chips, shavings pulp fibers made from, for example, softwood or hardwood, olives or bark, which may be bleached or unbleached, and waste fibers such as waste paper or waste board chemical cellulosic fibers (rayon) reusable materials, e.g. newsprint, cardboard and cardboard vegetable fiber, , coconut fibers, sisal 2. animal fibers, eg animal hair, camel hair, wool and pig bristles 3. synthetic organic fibers, eg polyamide, polyester and polyvinyl chloride fibers 4. synthetic ethical inorganic fibers (glass wool, slag, rock wool, kaolin wool, glass monofilaments and e.g. iron, steel, brass and aluminum fibers).

According to the invention, the fibers are dried and treated with a metal oxide acylate before, during or after dry fiberization.

The effect obtained by treating the fibers in question with metal oxide acylates is presumed primarily to result from a chemical reaction between the reactive groups of the fiber surfaces and the metal oxide acylates and, secondarily, from the metal acylate groups attached to the fiber surfaces during the reaction.

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The effect achieved in cellulose fibers is of particular interest. The effect can be described as the stabilization of cellulosic fibers in terms of the effect of the environment on several fiber properties. This stabilization comprises a number of properties and manifests itself, according to the metal oxide diacylate selected, in the form of inhibition of water absorption, improvement of time resistance, improvement of rigidity, heat resistance and rot resistance, as well as reduction of flammability and the achievement of antistatic properties. Treatment of both cellulose and man-made fibers with metal oxide acylates improves the dispersibility of the fibers in water or solvents, as well as substantially improves the binding to both organic and inorganic binders, which is crucial when the fibers are used in composites.

One of the main uses of many of the above-mentioned modified fibers is the Composite range, where the modified fibers can replace commonly used mineral fibers such as asbestos. Cellulose fibers treated with metal oxide diacylates can be used in composite materials not only as a substitute for asbestos, but also as a substitute for glass wool, rock wool-type mineral fibers, slag wool, kaolin wool, and the like. They can also be advantageously used in composite materials which already contain cellulose-based substances, e.g. in paper and board, giving them new and better properties.

Mineral fibers treated with metal oxide acylates, on the other hand, also have better properties when added to composites, as their ability to become fiberized and evenly distributed in the finished composite has been shown to be significantly improved when treated with metal oxide acylates.

In cellulose fibers treated with suitable metal oxide diacylates, one of the most important improvements is the inhibition of the reaction of the fibers with water. The cellulose fibers are themselves hygroscopic, and as they absorb water, the volume first increases due to swelling. This is a factor that causes harmful material stresses in the composite. As the tendency to swell in the metal oxide acylate treatment decreases or disappears, the composites containing such fibers acquire correspondingly better properties.

Since the cellulose fibers modified with metal oxide acylates exist as separate fibers which do not tend to accumulate 4,64664, the treated fibers can also be used immediately, e.g. as cavity insulators or as fillers for powders, bedding and the like.

The metal oxide diacylates mentioned in F1 Patent Application No. 781,770 are, as mentioned, a class of compounds invented by Dr. Jacobus Rinse and described, for example, in Belgian Patent No. 555,969, Dutch Patent No. 104,261, U.S. Pat. 3,087,949, 3,243,447, 3,177,238, 3,158,287, 3,625,934, 3,546,262, 2,634,674 and 3,673,229, in Belgian Patent No. 735,548 and in British Patents Nos. 1,230,412 and 1 274 718. Metal oxide diacylates comprise a large group of substances because both the metal and the acylate group can be varied over a wide range. The general composition of the metal oxide acylates is assumed to be divalent metal (R-Me-O-Me-R) linear compounds trivalent metal (O 2 -Me 2 -R 2) planar compounds tetravalent metal (O 2 -Me 2 -R 2) quaternary compounds wherein Me is metal atom, R is an acylate group which is an organic acid residue containing at least 12 carbon atoms, and x, y and z = 3 to 7 indicate the assumed molecular size in solution. It should also be noted that metal oxide diacylates can be prepared in which each molecule contains two or more different metals. compounds of this type have also been described in the above-mentioned patents.

Metal oxides tend to react with OH groups and other reactive groups present as free groups on fiber surfaces. The reaction rate is assumed to decrease as the complexity of the molecular structure increases, so that the metal oxide diacylates of tetravalent metals require higher temperatures or a longer time to achieve the reaction.

The choice of metal oxide diacylate to be used according to the invention must take into account the desired effects of the final product and the effects which the treatment with metal oxide diacylate has on the process properties of the fibers. This can be illustrated by the treatment of cellulosic fibers, whereby the appropriate choice of a combination of a metal and metal oxide diacylate acylate residue gives cellulose axes which are easily dispersible and have good binding to binders, and these fibers can be given a number of additional features. Thus, for example, a fire-resistant coating can be obtained by using aluminum or iron oxide dithalates or roe-thallium oxide acylates in which the metal is antimony, Zn and Cu oxide diacylates give rot resistance. Oxide acylates containing Mg and Fe usually improve the anti-static properties of the fibers and titanium oxide dithalate improves the stiffness of the fibers. By using styrene-modified aliphatic acids in the acylate residue, the alkali resistance of the fibers can be improved.

Since the different metal oxide acylates are completely compatible with each other, the combined effects can be achieved with the right composition of the metal oxide acylate treatment agent.

For example, in the treatment of cellulosic fibers and other fibers where it is important to improve water repellent properties, it should be noted that titanium-containing metal oxide acylates have substantially higher hydrophobicity efficacy than other metal oxide acylates and can therefore be used at substantially lower concentrations. so that combined effects are achieved.

As examples of desired properties, when the final product to be made using treated fibers is a composite material used for electrical insulation, the aim is to minimize the effect of water on the fibers. Reasonable water absorption is again an advantage when the fibers are to be used in connection with inorganic binders such as cement or gypsum.

One possible explanation for the decay-improving effect of metal oxide diacylates on organic fibers, in this case cellulose fibers, may be that the free 6 4 6 6 4 6 free alcohol groups on the surface of the original cellulose fibers play an important role in initiating both bacterial and fungal degradation mechanisms. , when the fibers are treated with a metal oxide acylate.

According to the invention, it is particularly important that it has been found that the pretreatment of the fibers with other types of wood impregnation or their treatment with other types of wood impregnation together with the metal oxide acylate treatment does not appear to affect the efficiency of the metal oxide acylate treatment. Thus, it has proved possible to combine e.g. paraffin treatment with e.g. alumina stearate treatment, in which case the two treatment agents were used from the ring solution. Thus, it is also possible to treat the fibers with a metal oxide acylate and at the same time with a polymer, e.g. a polyolefin, in the same solution. Chlorinated paraffins and other wax-type substances can also be combined with metal oxide diacylates and applied to the fibers from the same solution.

In addition, it has been found that e.g. cellulose fibers can be pretreated with inorganic compounds, e.g. inorganic rot inhibitors, in particular so-called With the types "CZC", "CCZC" and "CCA". The fibers are then treated with good results with metal oxide diacylate. In this case, however, the water must occasionally be removed if it has been used for impregnation with an inorganic anti-rot agent. A suitable dewatering method is azeotropic distillation with e.g. xylene.

It has been found that the amount of metal oxide diacylate normally required to achieve the desired effect is normally 0.5 to 8% by weight of metal oxide diacylate based on the weight of the fibers, often achieving a sufficient effect when using 1 to 4% by weight based on the weight of the fibers.

In principle, the treatment of fibrous materials with metal oxide acylates is based on the reaction between the metal oxide diacylate and the active groups on the surface of the fibers. Therefore, the aim is usually to process separate fibers or bundles of fibers and not uniform fibrous materials such as sheets, webs, etc.

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The manufacturer normally supplies synthetic organic and inorganic fibers as well as animal fibers as separate fibers in the desired manner, but this is not always the case for cellulosic fibers. The cellulosic fibers can be obtained, for example, as dense pulps, such as raw board or recycled board or paper for the production of wood pulp, or as semi-dense pulps, such as the so-called pulp for the production of wood pulp. as "flash-dry" fibers or rags.

When the starting material is in such a uniform or semi-uniform form, it may be subjected to a defibering operation. Such defibering can be carried out according to known methods, i.e. either as a dry fiber in which the starting material is converted into loose fibers in an impact mill or a hammer mill by decomposition, or as a wet fiber to obtain a fiber suspension in water by mechanical action (blending) and reduced cohesiveness of cellulose fibers. The suspension obtained after wet fiberization can be concentrated by filtering or centrifuging off most of the water, after which the remaining water can be removed by azeotropic distillation, e.g. with a carbohydrate such as toluene or xylene. In this case, the fibers are obtained in a slurry in an organic substance in which the metal oxide diacylate treatment can be carried out. An additional advantage of using these carbohydrates in the distillation process is that they are immiscible in water, so that they can be recovered without special measures.

When the fiberization is performed as a dry fiber, it can be immediately combined with a metal oxide acylate treatment, whereby the heat generated by machining can be used to dry cellulose fibers to the desired extent and maintain the temperature at a level metal oxide diacylate is added. For example, in the dry fiberization of cellulosic materials, the metal oxide acylate can also be added immediately before the dry fiberization, whereby the mechanical work and temperature rise immediately following the fibers reach the required dryness and the temperature required for reaction with the metal oxide acylate.

t 8 64664 The temperatures at which the reaction between the fibers and the metal oxide diacylate is sought depend on the identity of the metal oxide diacylate. For example, alumina stearate reacts rapidly even at temperatures of 20-40 ° C, while when using, for example, titanium oxide acylates, a higher reaction temperature of 40-80 ° C must be sought. In principle, any higher temperature up to about 200 ° C can be used, since the metal oxide acylates have excellent resistance to these temperatures. Therefore, the temperature resistance of the fibers often determines at which temperature the treatment must be performed.

In the treatment, the fibers can be immersed in or moistened with a metal oxide acylate solution, in addition to which the metal oxide diacylates can be applied to the fibers sim. by spraying with the fibers resting on the air immediately after dry fiberization.

In the treatment, the amount and concentration of the solution are adjusted according to the desired degree of reaction, i.e. the amount of metal oxide diacylate that is desired to be absorbed on the surface of the fibers. The solvent is suitably a carbohydrate or chlorinated carbohydrate which, for introduction into the liquid phase, suitably has a boiling point higher than the reaction temperature at which the attachment is allowed to take place. This avoids uneven deposition of the metal oxide acylate caused by too rapid evaporation of the solvent. On the other hand, for some purposes it may be desirable to add the metal oxide diacylate to a solvent which evaporates very rapidly, e.g. freon, as described in application No. 2451/77. Once the reaction between the fibers and the metal oxide diacylate has taken place, a solvent having a boiling point significantly higher than the reaction temperature, filtration or centrifugation of the solvent and evaporation of the solvent remaining on the surface of the fibers are carried out so that almost no solvent remains in the fibers.

For a successful reaction between different fiber types and metal oxide acylates, it is considered very important that the fibers are dry in treatment because the metal oxide acylates are highly reactive with water to form soaps and do not undergo the desired chemical reaction under these conditions. with. It has been found that suitable dryness is achieved when the fibrous materials have been dried to constant weight at reasonable temperatures, e.g. 40-60 ° C.

The fibers treated with the metal oxide diacylate and optionally other treatment agents can then be formed in combination with an inorganic or organic binder in a conventional manner. At this stage, they have been found to fiberize much more easily than the corresponding fibers which have not been treated with metal oxide diacylate. The compounds in question may be similar to those described in Danish Patent Application No. 2451/77. Fibers treated with metal oxide acylate have been found to be ideally evenly distributed in such composites even at high concentrations compared to the uneven distribution often associated with non-fibrous clumps of material and characteristic of the same substances when not treated with metal oxide diacylate.

The preparation of the composite materials using fibers prepared in accordance with the principles of the present invention occurs by any method of preparing such composite materials. When, for example, your combination is made by wet-fiberizing metal oxide-treated fibers and combining them with an inorganic binder, it has proven expedient to perform flocculation of the fibers together with an inorganic binder using e.g. a cationic type flocculant such as It has been found that the use of treated fibers results in, for example, complete "precipitation" of cement on the surface of the fibers and complete retention in subsequent dewatering. The fibers treated according to the invention can also be used to replace mineral fibers in the composite materials described in Danish Patent Application No. 5436/76 and in the applications of other countries for which priority has been claimed from Danish Patent Application No. 5436/76.

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It is clear that any suitable impregnation method described in Danish Patent Application No. 2451/77, including pressure impregnation and pressure / vacuum impregnation, can be used to treat the fibrous material with metal oxide acylate. For example, when vacuum impregnation can be excellently combined with pressure / vacuum impregnation using suitably shaped closed equipment.

The invention is further illustrated by the following examples.

Example 1

Treatment of cellulose fibers in the form of sheet cellulosic fibers_ 200 g of sulphate cellulose (dried to constant weight at 60 ° C) was broken up into smaller pieces which were slurried in a solution containing 11.43 g of 30% mineral turpentine containing alumina 14 Moate 70), in 2 liters of mineral turpentine, corresponding to an amount of alumina distearate of 4% by weight relative to the amount of cellulose. The slurry was kept at 40 ° C with stirring for 1 hour.

The liquid phase was filtered off and the treated cellulose was dried for 4 hours at 100 ° C.

On the basis of the treated cellulose, paper sheets 2 (250 g / m 2) were prepared by dispersing the cellulose in water in a mixer and forming the sheets in a laboratory sheet former.

The resulting sheets were loose - without cohesive force - and water repellent, and swelled very little when immersed in 2N NaOH-Liu. In contrast, the sheets made from the starting material were normally cohesive and strongly water-absorbing, and swelled to about twice the thickness in 2N NaOH solution.

Example 2

Manufacture of fiber cement slabs

The cellulosic fibers prepared according to Example 1 were used as reinforcing elements for fiber cement boards.

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8 mm thick slabs containing 6% cellulose fibers and 94% fast setting cement were prepared as follows: 24 g of cellulose fibers treated as described in Example 1 were defibered in 2 liters of water in a mixer, then 376 g of fast setting cement was added and the mixture was thinned. 10 liters. Upon addition of 50 ml of a 1/4% flocculant solution (Prodefloc Cl, a highly cationic flocculant based on high molecular weight polyacrylamide with its associated quaternary ammonium groups), the cellulose particles were precipitated on the surface of the cellulose fibers, followed by flocculation. The 8 mm thick plates were assembled into one layer and some into two layers, four layers and eight layers, respectively, whereby the different materials were formed by combining the layers and each time in a laboratory sheet former a material about twice the desired final thickness was produced. The water removed was perfectly clear, so it was a complete retention of the cement.

The tiles were pressed to a thickness of 8.5 mm, removing excess water. The tiles were then cured for 1 day at room temperature, after which they were dried for 1 day at 80 ° C. During curing, the thickness of the tiles did not change.

The resulting tiles were water-repellent and sealable, and microscopically showed a particularly uniform distribution of fibers.

Example 3

Treatment of dry-fiberized sulphate cellulose fibers with titanium oxide acylate__ 50 g of sulphate-cellulose fibers, dry-fiberized in a hammer mill and (after intermediate storage) dried to constant weight at 60 ° C, were treated with 400 ml of a 50% solution containing 50%. 64664 containing an amount corresponding to the desired treatment of titanium oxide acylate (Moaco D-42-00, in which the acylate has reacted with a styrene conjugated fatty acid) and, on the other hand, paraffin with a melting point of 55-60 ° C, taking into account that the fibers absorb 8 g solvent / gram of fiber.

After the wetted fibers were kept at room temperature for 2 hours, the reaction between the titanium oxide diacylate and the fibers was carried out, and the fibers were dried by keeping the fibers at 100 ° C for 12 hours.

The resulting fibers were loose and disabled. Paper sheets were made from the fibers in a laboratory sheet former. The amounts of treatment agent used and the test results are shown in the following table:

Table I

Experiment 1 2 3 4 5 6 Titanium oxide diacylate added during treatment 1% 2% 1% 1% 0% 0% paraffin 0% 0% 2% 1% 2.5% 1%

Impact on sheets of paper:

The materials prepared in Experiments 1-4 were felt-like, without strength, strongly water-repellent, and only moderately swellable when immersed in 2N sodium hydroxide solution. The materials prepared in Experiments 5-6 had near normal strength, moderate water repellency, and moderate swelling.

Example 4 Preparation of treated cellulosic fibers by wet fiberization and azeotropic distillation___ 20 g of sulphate cellulose fibers were defibered in 2 liters of water in a blender, after which the excess water was filtered off. A filter cake weighing 170 g (water content 150 g) was transferred to a distillation flask and 500 ml of xylene was added. This was distilled until the distillate was pure xylene - the condensation point in the vapor phase rises above 100 ° C. As cellulose fibers and xylene formers, 1.4 g of Moaco C-14-70 (corresponding to 1 g of alumina stearate) was added to the slurry, which reacted spontaneously with the fibers at this temperature.

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Excess xylene was removed by filtration and the treated cellulose fibers were dried.

The sheets of paper prepared from the treated cellulosic fibers as described in Example 1 had a loose and non-uniform structure and were water repellent and swelled only slightly in a 2N NaOH-Liu branch.

Example 5

Preparation of fiber cement board from treated wood chips 500 g of wood chips (spruce / pine, starting material for wood pulp production) were treated with 200 ml of a solution containing 14 g of Moaco C-14-70 (alumina stearate content 10 g) in a mineral turpentine for 10 minutes with stirring type. The wood chips then completely absorb the liquid phase. The wood chips were then dried for 6 hours at 80 ° C in an oven, at which point the alumina stearate reacted with the cellulose.

490 g of the wood chips thus dried were mixed with 210 g of fast-setting cement in a mixer, first dry, then with the addition of 300 ml of water. The resulting semi-dry paste was divided into a mold and pressed to a thickness of 15 mm. The cement was cured for 10 days at room temperature and 100% relative humidity. The resulting tile had a compact structure and a smooth surface, and was water-repellent as well as sealed.

Example 6

Treatment of glass wool and rock wool with alumina stearate and preparation of fiber cement board from the fibers thus treated 200 g of white glass wool were dried to constant weight at 80 ° C, after which the glass wool was moistened with a solution containing 2 g of alumina stearate (2.8 g Moaco-C-14-70) 1 6 liters of mineral turpentine. The wetted fibers were kept at 30 ° C for 2 days, after which they were dried at 60 ° C.

The impregnated glass fibers were completely different in quality from the source glass fibers because they appeared "cotton-like" and much softer and did not have the normally adhesive property of the starting fibers when touched.

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A fiber cement board was then prepared containing 12% of the glass fibers thus treated and 88% of the fast-setting cement.

48 g of treated glass fibers were defibered in 2 liters of water in a blender. The defibering was complete, and no fiber bundles were observed that occur when attempting to defibrate the corresponding untreated glass fibers. 325 g of cement were then mixed and the slurry was diluted to 10 liters. It was floated by adding 50 ml of a 1/4% Prodefloc Cl solution, followed by the formation of a plate by filtering off the water in a laboratory sheet former. The water removed was perfectly clear, indicating that the retention was complete. Filtration was performed on a 40 mesh wire cloth. The filter cake was pressed to a thickness of 8.5 mm, which also removed excess water. The tile was cured for 7 days at room temperature and 100% relative humidity.

The prepared tiles had a low porosity, and under microscopy the fibers were found to be very evenly distributed in the cement matrix.

The experiment was performed in exactly the same manner using 200 g of Rockwool ® fibers, which is a commercial grade treated in the usual manner with oil and phenolic resin. However, the Rockwool fibers were not dried prior to impregnation with the alumina stearate account.

In the above examples using cement, each experiment has been performed with a Blaine number of about 2800, about 3200, about 3600, and about 4300, respectively. Low Blaine numbers achieve significantly faster dewatering time from the laboratory sheet than higher Blaine numbers.

Example 7

Treatment of cellulosic fibers combined with defibering in a hammer mill ___ The treatment used an apparatus consisting of a hammer mill equipped with a variable speed feeder 64664 for feeding the cellulosic pulp in a web-like manner, with a treatment feeder placed immediately in front of the feeder. This feeder was here a flat "Air-Less" spray nozzle mounted at such a distance from the pulp web that the fan-like shower just barely moistened the web.

By adjusting the nozzle dosage amount as well as the pulp feed rate, the treatment agent supply was adjusted.

Using the equipment described above, two types of modified cellulose fibers were prepared: 1. To 2500 g of sulfate cellulose, 5% alumina stearate was added by spraying a 50% solution thereof in a solution containing equal amounts of mineral turpentine and petroleum.

Prior to treatment, the cellulose pulp was dried to constant weight at 50 ° C for 18 hours. The fibers obtained after the treatment were dried for 12 hours at 90 ° C in an oven with air exchange to remove residual solvent.

2. To 2500 g of sulfate cellulose was added a mixture of 4% alumina stearate and 4% paraffin oil. The addition was carried out by spraying a mixture containing 1.67 parts by weight of alumina stearate in a 60% mineral spirits solution and 1 part by weight of paraffin oil, whereby 10% by weight of this mixture was introduced into the pulp.

Again, the fibers were dried as described above before and after defibering.

The addition of treatment chemicals is a significant advantage in performing the defibering step. This advantage is particularly evident in the fact that the treated fibers contained significantly less cellulose dust than the untreated ones. This fact was immediately established when processing the fibers.

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Example 8

Investigation of the effect of the treatment of cellulose fibers described in Example 7______________

The immediate effect of treating cellulosic fibers is to reduce the reaction of cellulosic fibers to water.

This was determined as follows: Using a well-known method of making paper sheets in a laboratory sheet former, paper samples 2 with a sheet weight of 250 g / m 2 were prepared partly from treated fibers and partly from a mixture containing 75% treated fibers and 25% untreated fibers because untreated fibers are needed. to obtain a sheet of paper with the cohesive force required to perform the measurements.

The measurement was the determination of the shrinkage of a sheet of paper, i.e. its change in length as it transitioned from a fully wetted state to a dry state.

The results of this study showed the following: untreated fibers 4.8% shrinkage fibers with the addition of 5% alumina stearate 1.7% shrinkage fibers with the addition of 4% alumina stearate + 4% paraffin oil 1.1% shrinkage

It is observed that the shrinkage of the paper was substantially reduced as a result of the treatments; the measured shrinkage can mainly be calculated for the presence of untreated fibers.

Example 9

Examination of Treated Cellulose Fibers Used as Cement Matrix Fiber Reinforcement __________ The modified cellulose fibers described in Example 7 were used in these studies.

The following composition and method of manufacture were used for the fiber-cement studies: 64664 17

Composition: cellulose fibers 16 g 6.78% by weight of cement powder 220 g 93.22% by weight of water 400 ml, i.e. a water / dry matter ratio of 1.69.

The amounts used corresponded to a tile measuring 200 x 80 x 8 3 mm.

Method:

A "Braun" mixer with 3 speeds was used as the mixing machine. The cement and water were mixed, after which the fibers were added for 1 minute, and mixing was continued for 2 minutes.

Flocculant, 10 ml of 0.2% Pro-deflock Cl solution was then added and stirring was continued for 0.5 minutes.

The mixture was transferred to a filter box having a target plate length / width measure. After filtration of the water, the filter cake was transferred to a mold and pressed to a final thickness, further draining the water. It was found that the filtered water was clear and did not contain cement granules.

The pressed tiles were cured at room temperature and 100% relative humidity for 2 weeks, after which the tiles were air dried.

The flexural strength of the prepared tiles was studied in both air-dry and wet conditions, whereby the wet state was obtained by immersing the air-dried tiles in water for 2 days.

The results of the experiment were as follows:

Bending strength kp / cm

Fiber type Dry Wet untreated 220 105 Added 5% alumina stearate 225 130 Added 4% alumina stearate + 230 150 4% paraffin oil

Claims (8)

A method of making substantially separate fibers treated with metal oxide acylate, characterized in that the fibers are dried and treated with the metal oxide acylates before, during or after the dry defibration. Process according to claim 1, characterized in that the dry defibration is carried out in a hammer mill. 3. A process according to claim 1 or 2, characterized in that the dried fibers are treated with the metal oxide acylate prior to the dry defibration. 4. A process according to claim 1 or 2, characterized in that the dried fibers are treated with the metal oxide acylates in the airborne condition after the dry defibration. 5. A method as claimed in any one of claims 1-4, characterized in that the dry defibration is carried out by heating to constant weight. 6. A process according to any one of claims 1-4, characterized in that the drying is carried out by means of azeotropic distillation with a hydrocarbon. Process according to any of the preceding claims, characterized in that the metal oxide acylates are aluminum oxide acylate or titanium oxide acylate. Process according to any of the preceding claims, characterized in that the fibers are inorganic fibers or cellulose fibers. The use of the fibers treated with mixed metal oxide acylate by the process according to some of the preceding claims.