FIBER MATERIAL AND PROCESS FOR ITS PREPARATION

Abstract: Fiber materials, especially for use as reinforcing fiber element in composite materials based on organic and/or inorganic binders, are treated with metal oxide acylates, which facilitates the ability of the fibers to become defibrated and uniformly distributed in the final composite material. Cellulose fibers treated with e.g. aluminum oxide stearate or titanium oxide acylate do not swell with water and do not tend to comglomerate. During treatment with metal oxide acylates the fibers should be dry.

Description: TITLE : FIBER MATERIAL AND PROCESS FOR ITS PREPARATION . The present invention relates to a process for treatment of fibers . Danish patent application No . 2451/77 describes a process for im- pregnating cellulose fibers and fields of application of these impreg¬ nated fibers, especially the use of the fibers as reinforcing fiber- element in composite materials based on organic or inorganic bin- ders or a combination of organic and inorganic binders . One class of the treatment or impregnation agents described in the above-mentioned patent application has been found to have especially valuable properties, as treatment with these can provide n ot only cellulose fibers , but also other fiber materials with un¬ expected and extremely desirable property improvements . The fibers in question, which, when treated with metal oxide acylates , may be modified in the desired way as regards their properties , are cellulose fibers of any kind, animal fibers and synthetic fibers of both inorganic and organic origin, also including metal fibers . The fibers in question may be discrete fibers or fiber bundles or "coarser" materials such as wood vlies or wood wool. Main groups of fiber materials of the invention advantageously treated with metal oxide acylates are the following: 1) Cellulose-based materials : Finely divided wood such as wood wool, wood chips , shavings ; cellulose fibers from the paper industry, including e.g. mechanical wood pulp semichemical wood pulp fully-chemical wood pulp and other cellulose pulps of the types mentioned in the above Danish patent application No . 2451/77; chemical cellulose fibers (rayon) ; recycled material, e . g. old papers, cardboard and paste- OMPI V Λ- iPO .* board; vegetable fibers , e.g. flax, bast, coconut fibers, sisal. 2) Animal fibers , e.g. cattle's hair, camel hair, wool and pigs' bristles . 3) Synthetic organic fibers , e.g. fibers of polyamide, polyester, polyvinyl chloride. 4) Synthetic inorganic fibers (glass wool, slag wool, rock wool, kaolin wool, glass mono-filaments and fibers of e .g. iron, steel, brass and aluminum) . The effect obtained by treating the fibers in question with metal oxide acylates is supposed to result primarily from the chemical reaction between reactive groups on the fiber surfaces and the metal oxide acylates, secondarily from the metal acylate groups fixed on the fiber surface by the reaction. The effect obtained per cellulose fiber is particularly interesting. This effect can be described as a stabilization of the cellulose fiber towards influence from the surroundings on a number of fiber properties . This stabilization includes a number of proper¬ ties, and, according to the particular choice of metal oxide acy- late, manifests itself in a blocking of the water absorption, an increase in the alkali resistance, an increase in rigidity, thermal stability, rot resistance and a decrease in inflammability and ob¬ taining of antistatic properties . When treated with metal oxide acylates both cellulose fibers and synthetic fibers will obtain a considerable improvement of the ability to disperse in water or solvents and a considerably increased coupling effect towards both organic and inorganic binders , which is of decisive impor¬ tance when using the fibers in composite materials . One of the most important applications of a number of the above- mentioned fibers in modified form is the composite field where the modified fibers may replace usually applied mineral fibers such as asbestos . Cellulose fibers treated with metal oxide acylates may be used in composite materials as a substitute for not only asbestos , but also glass wool, mineral fibers of the rock wool type, slag wool, kaolin wool, etc . ,. but they are also advantageously applicable in composite materials already containing cellulose-based - materials, e . g. paper and cardboard, and thus add new and im¬ proved properties to these materials . On the other hand, mineral fibers treated with the metal oxide acylates also show improved properties when incorporated in com¬ posite materials , as their ability to become defibrated and uniformly . dispersed in the final composite material has been found to be dramatically increased when they are treated with the metal oxide acylates . One of the most important improvements ascertained in the cel¬ lulose fibers treated with suitable metal oxide acylates is -a blocking or hindrance in the reaction of the fiber towards water. Cellulose fibers are hygroscopic per se, and o water absorption primarily an increase of volume caused by swelling occurs , which will result in disadvantageous internal material tensions in a composite material. When the tendency to swell is reduced or completely eliminated by treatment with a metal oxide acylate, composite materials con¬ taining such fibers obtain correspondingly improved material pro¬ perties . As cellulose fibers modified with metal oxide acylates appear as discrete fibers not having a tendency to conglomerate, the treated fibers per se may also be used directly, e . g. as insulating material in cavities or as stuffing in pillows , bedding, etc . As described in Danish patent application No . 2451/77 metal oxide acylates are a class of compounds invented by Dr . Jacobus Rinse and e . g. described in Belgian patent No . 555,969, Dutch patent No . 104,261, US patents Nos . 3,087,949, 3,243,447, 3, 177,238, 3,518, 287, 3,625,934, 3,546, 262, 3,634,674 and 3, 673 , 229, Belgian patent No. 735,548 and British patents Nos . 1 , 230,412 and 1,274, 718. The metal oxide acylates comprise a large group of substances , as both metal and acylate group may be varied within a wide range. The general composition of the metal oxide acylates is supposed to be divalent metal (R-Me-O-Me-R) Λ. linear compounds trivalent metal (O„-Me 3 -R 3 ) planar compounds tetravalent metal (O β -Me 4 -R 4 ) tetrahedron shaped- compound wherein Me is a metal atom, R is an acylate group which is an organic acid residue with at least 12 carbon atoms and x, y and z = 3 - 7 is a supposed molecular size in solution . It should be noted that metal oxide acylates wherein each molecule contains two or more different metals possibly of different valence, may also be produced, and such types of compounds are also describ in the above-mentioned patent specifications . The metal oxides tend to react with OH groups and other reactiv groups present as free groups on the fiber surfaces . The reacti rate is supposed to decrease with increasing complexity of the molecular structure so that the metal oxide acylates of tetravalen metals require higher temperatures or more time in order to obta reactio . When choosing the metal oxide acylate to be used according to the invention, the desired effects of the end product and the effects on the processing properties of the fibers when treated with the metal oxide acylate are to be considered. This may be illustrated by the treatment of cellulose fiber, as a suitable choi of the combination of metal and acylate residue in the metal oxid acylate may confer a number of further properties besides the o tainment of cellulose fibers which are easily dispersable and hav an effective coupling to binders . Thus e .g. fire resistance may obtained by using aluminum or iron oxide phthalates or metal oxi acylates wherein the metal is antimony, Zn- or Cu-oxide acylates provide rot resistance, Mg- and Fe- containing oxide acylates will usually increase the antistatic properties of the fibers, and titan oxide phthalate will increase the rigidity of the fibers , while the use of styrene modified aliphatic acids in the acylate residue res in an improvement of the alkali resistance of the fibers . As the different metal oxide acylates are mutually fully compatible, combined effects may be obtained by correct combination of the metal oxide acylate treatment agent. In connection with the treatment of e.g. cellulose fibers and other fibers , where an increase of the water repellent properties is im¬ portant, it is important that metal oxide acylates containing tita- nium show a considerably higher effect with respect to hydro- phobization than other metal oxide acylates which make them ap¬ plicable in considerably smaller concentrations and thus permit admixture of other metal oxide acylates in order to obtain com¬ bination effects . Examples of desired properties are e .g. : when the end product to be produced with the treated fiber is a composite material for electrical insulation, a minimization of the water sensitivity of the fibers is desired, whereas it would be advantageous with a mode- rate water absorption, when the fibers are to be used in connection with inorganic binders such as e.g. cement or plaster. A possible explanation of the rot resistance-improving effect, which the metal oxide acylates impart to organic fibers including cellulose fibers, may be that the free alcohol groups on the surface of the native cellulose fibers play an important part in the initiation of both the bacterial and fungal deterioration mechanism, and that such free alcohol groups are blocked when the fibers are treated with a metal oxide acylate . According to the invention it is of special importance that a pre- treatment of the fibers with other types of wood impregnation or a treatment of the fibers with other types of wood impregnation together with the treatment with metal oxide acylates does not seem to influence the effect of the metal oxide acylate treatment. Thus , it has been found possible to combine a treatment with e . g. paraffin with a treatment with e . g. aluminum oxide stearate, as these two treatment agents were applied from the same solution . Thus , it will also be possible to combine a treatment with metal oxide acylate with simultaneous application of a polymer, e .g. a polyolefine, applied from the same solution . Chlorinated paraffines and other materials of the wax type may also be combined with the metal oxide acylates and be applied o fibers from the same solution . Besides, it has been found that e.g. cellulose fibers may be pre treated with inorganic compounds, e.g. inorganic wood preserva agents, especially the so-called "CZC" , "CCZC" and "CCA" type and thereafter successfully be treated with metal oxide acylate, these cases, however, requiring an intermediate removal of wate provided this has been used when impregnating with an inorgani preservation agent. A suitable way of removing the water is aze tropic distillation with e. g. xylene. It has been found that the amount of metal oxide acylate usually to be used in order to obtain the desired effect is normally with the range of 0.5 - 8% by weight of metal oxide acylate, calculate on the weight of the fiber, as in many cases a sufficient effect is obtained when adding between 1 and 4% by weight, calculated on the fiber. I principle the treatment of fiber materials with metal oxide acy lates comprises a reaction with the metal oxide acylate on active groups on the fiber surface, and it is therefore usually preferre to treat discrete fibers or fiber bundles instead of treating cohe rent fiber materials such as sheets, rolls, etc. Synthetic organic and inorganic fibers and animal fibers will normally be in the desired discrete form already from the producer, but this is not always the case with cellulose fibers . The cellulose fibers may e.g. be in the form of compact pulps such as raw cardboard from the wood cellulose manufacture or recycled cardboard and paper or semi-compact pulps such as the so-called "flash-dry" fiber from the wood cellulose production or as rags . In such cases where the starting material is present in such a coherent or semi-coherent form the starting material must be sub¬ mitted to a defibration process . Such a defibration process may be performed according to known methods , i. e . either a dry de- fibration, wherein the starting material is transformed into loose fibers by defibration in an impact mill or hammer mill, or a wet defibration, wherein a suspension of fibers in water is obtained by the combined effect of mechanical stimulation (stirring) and the reduced coherence ability of cellulose fibers in aqueous sur- roundings . After wet defibration the obtained suspension may be concentrated by filtration or centrifugation of the majority of water whereupon the rest of the water may be removed by azeotropic distillation with e.g. a carbon hydride such as toluene or xylene. Thus, the fibers are obtained in a slurry in an organic medium wherein the treatment with a metal oxide acylate may be performed. A further advantage of using these carbon hydrides for the distil¬ lation process is that they are immiscible with water and thus : may be recovered without special precautions . When the defibration process is performed as dry defibration the dry defibration may be immediately combined with a treatment with a metal oxide acylate, as the heat developed during the mechanical treatment may serve partly to dry out the cellulose fibers to the desired degree and partly to keep the temperature at a level where the reaction between the fiber surface and the metal oxide acylate proceeds rapidly, at the same time while the elevated temperature contributes to evaporation of the solvent in which the metal oxide acylate is applied. When e . g. a ceEulose material is dry defibra¬ ted, the metal oxide acylate may also be applied immediately before the dry defibration, as the immediately subsequent mechanical treatment and temperature increase result in the fact that the fibers obtain the necessary dryness and the temperature necessary for the reaction with the metal oxide acylate . The temperatures which are preferred for obtaining the reaction between the fibers and the metal oxide acylate will depend on the identity of the metal oxide acylate. Aluminum oxide stearate, for example, reacts reasonably rapidly already at temperatures between 20 and 40°C, while oxide acylates of titanium require a higher reaction temperature in the range of 40 - 80°C . In princi any elevated temperature of up to about 200°C may be used, as the metal oxide acylates are perfectly capable of withstanding th temperatures, and thus it is often the temperature resistance of the fibers which is decisive for the temperature at which the tre ment is to take place. Besides an application wherein the fibers are immersed in or wet ted with a solution of metal oxide acylates the metal oxide acylat may be applied e.g. by spraying while the fibers are in airborn condition . immediately subsequent to a dry defibration. During the treatment the amount of solution and its concentratio is adapted to the desired degree of reaction, i. e. the amount of metal oxide acylate which it is desired to apply on the fiber. Th solvent is suitably a carbon hydride or a chlorinated carbon hyd which, for application in liquid phase, has suitably a boiling poi which is higher than the reaction temperature at which the coupl process proceeds . Thus , an irregular depositing of the metal oxi acylate caused by a too rapid evaporation of the solvent is avoid On the other hand it may be desirable for certain purposes to apply the metal oxide acylate in a solvent which evaporates very quickly, e.g. freon such as described in Danish patent applicati No. 2451/77. When the reaction between the fibers and the metal oxide acylate has proceeded, a filtration or centrifugation of the solvent and an evaporation of the solvent remaining on the fiber is performed, when a solvent with a considerably higher boiling point than the reaction temperature has been used, so that the fibers become practically free of the solvent. It is supposed to be of considerable importance for the success¬ ful reaction between the various types of fibers and metal oxide acylates that the fibers are dry when treated, as the metal oxid acylates show a very high reactivity with water with formation o soaps and under such circumstances would not enter into the de sired chemical reaction with reactive groups on the fiber surface It has been found that a suitable dryness has been obtained, w _ the fiber materials have been dried to a constant weight at moderate temperatures , e .g. 40 - 60°C . The fibers treated with metal oxide acylate and optionally other agents may then in the usual way be incorporated in composite materials with inorganic or organic binder, and in this process it has been found that they are defibrated much more easily than corresponding fibers which have not been treated with metal oxide acylate . The .composite materials in question may be of the same kind as the materials described in Danish patent application No . 2451/77. In such composite materials the metal oxide acylate-treated fibers have been found to be distributed in the ideal uniform way, also in large concentrations , in contrast to the non-uniform distri¬ bution, often with lumps of non- defibrated material, which is often characteristic to the same materials when they have not been treated with metal oxide acylate . The preparation of composite materials using fibers produced in accordance with the principles of the present invention is carried out in any known way for preparing such composite materials . When e. g. the composite material is prepared by wet defibration of the metal oxide-treated fibers and combination with an inorganic binder, it has been found to be suitable to flocculate the fibers together with the inorganic binder using a flocculating agent, e . g. a flocculating agent of the cationic type such as Prodefloc Cl , which is a polyacrylamide product having attached quaternary ammonium groups . It has been found that when using the treated fibers a perfect "precipitation" of e . g . cement on the fiber surface is obtained together with a complete retention in the subsequent dehydration. The fibers treated according to the invention may also be used as a substitute for mineral fibers in the composite materials described in Danish patent application No . 5436/76 and applications in other countries and claim priority from Danish patent application No. 5436/76. It is evident that when treating the fiber material with the metal oxide acylate, any suitable impregnation method mentioned in Danish patent application No. 2451/77 may be used, also including pres- sure impregnation and pressure/vacuum impregnation, and a dry ■ defibration process may e.g. be combined with a pressure/vacuu impregnation by means of a suitable embodiment of a closed appa- ratus . The invention is further illustrated in below Examples , Example 1. Treatment of cellulose fiber in the form of pulp fibers in sheets . 200 g of sulphate cellulose (dried to a constant weight at 60°C) were disintegrated into smaller pieces which are suspended in a solution of 11,43 g of white spirit (30%) containing an aluminum oxide stearate product (Moaco C-14-70) in 2 liters of white spirit corresponding to an amount of aluminum oxide stearate of 4% by weight in relation to the amount of cellulose . The suspension is kept at 40°C with stirring for 1 hour. The liquid phase is filtered and the treated cellulose is dried for 4 hours at 100°C . 2 Paper sheets (250 g/m ) are prepared on the basis of the treated cellulose by dispersing the cellulose in water in a blender and forming sheets on a laboratory sheet former. The resulting sheets are loose - without any coherency - and water-repellent with only a sligth swelling when immersed in a 2N NaOH- solution. In contrast to this the sheets of the starting material are normally coherent and strongly water- absorbing, and they swell to about twice the thickness in a 2N NaOH-solution. Example 2. . . Preparation of fiber cement sheet. Cellulose fibers prepared as described in Example 1 were used as reinforcing element in fiber cement sheets . Sheets with a thickness of 8 mm with a content of. 6% cellulose fibers and 94% rapid cement were prepared in the following manner: 24 g of the cellulose fibers treated as described in Example 1 were defibrated in 2 liters of water in a blender, whereafter 376 g of rapid cement were admixed, and the mixture was diluted to 10 liters . By adding 50 ml of a solution (1/4%) of a flocculation agent (Prodefloc Cl, which is a strong cationic flocculation . agent on the basis of a high molecular weight polyacrylamide having at- tached quaternary ammonium groups) , the cement particles are precipitated on the cellulose fibers , whereafter the flocculated suspension is formed to sheets on a laboratory sheet former. The 8 mm thick sheets were constructed partly in one layer and partly in two layers, four layers and eight layers , respectively, as the layered materials were provided by superimposing the layers, and each time producing a material of about twice the thickness of the desired end thickness in the laboratory sheet former. The - drained water was absolutely clear, and thus a complete retention of the cement was obtained. The sheets are compressed to a thickness of 8.5 mm so as to re¬ move surplus of water. Thereafter, the sheets are cured for 24 hours at room temperature and then dried for 24 hours at 80°C . During the curing the thickness of the sheets remains unchanged. The resulting sheets are water-repellent and nailable and show, in microscopy, an extremely uniform fiber distribution . - Example 3. Treatment of dry defibrated sulphate cellulose fibers with tita¬ nium oxide acylate . ITU EΛTΓ _ OMPI , A,m WiPO 50 g of sulphate cellulose fibers which had been dry defibrated in a hammer mill and (after . intermediate storing) dried to a con stant weight of 60°C, are treated with 400 ml of a solution in white spirit (50%) and extraction petrol (50%) containing the cal culated amount, corresponding to the desired treatment, of part titanium oxide acylate (Moaco D-42-OO, wherein the acylate is a styrene-reacted conjugated fatty acid) , and partly paraffin with a melting point of 55 - 60°C; in the calculations the fact that t - fibers absorb 8 g of solvent per g of fiber has been taken into account. After storing of the moistened fibers at room temperature for 2 hours, the reaction between the titanium oxide acylate and the fibers and drying out of the fibers is carried out by keeping t fibers at 100°C for 12 hours . The resulting fibers are loose and cotton-like. Paper sheets are prepared from the fibers in a laboratory sheet former. The amo of applied treatment agent and the test results appear from bel table: TABLE I Test 1 2 3 4 5 6 Treatment addition, titanium oxide acylate 1% 2% 1% 1% o% o 0% paraffin 0% 0% 2% 1% 2,5-g 1% Effect on paper sheets : The materials prepared according to tests 1 - 4 are felt-like wit strength, strongly water-repellent and only moderately swelling when immersed in a 2N sodium hydroxide solution. The material prepared according to tests 5 - 6 show almost normal strength, moderate water repellence and moderate swelling. "B Example 4. 5 Preparation of treated cellulose fibers by wet defibration and azeo- tropic distillation. 20 g of sulphate cellulose fibers are defibrated in 2 liters of water in a blender, whereafter the surplus of water is filtered off . The Q filter cake weighing 170 g (water content 150 g) is transferred to a distillation flask and 500- ml of xylene are added . Distillation is performed until the distillate is pure xylene - the condensation point in the vapour phase increases to above 100°C . To the sus¬ pension of cellulose fibers in xylene 1 ,4 g Moaco C-14-70 (corres- ponding to 1 g of aluminum oxide stearate) is added, which at this temperature reacts spontaneously with the fibers . Surplus of xylene is removed by filtration, and the treated cel¬ lulose fibers are dried. Paper sheets prepared from the treated cellulose fibers in the same manner as described in Example 1 show a loose and inco¬ herent structure, water-repellence and only slight swelling in 2N ' NaOH- solution . Example 5. Preparation of a fiber cement sheet from treated wood chips . 500 g wood chips (of spruce/pine, starting material for the pre¬ paration of wood cellulose) are treated with 200 ml of a solution of 14 g Moaco C-14-70 (content of aluminum oxide stearate 10 g) in white spirit in a blender of the kneading type for 10 minutes . Thereby, the liquid phase is completely absorbed by the wood chips . The wood chips are then dried for 6 hours at 80°C in an oven, whereby the aluminum oxide stearate reacts with the cel¬ lulose . 490 g of the dried wood chips are mixed with 210 g of rapid ceme in a blender, at first dry, then with addition of 300 ml water. The resulting half-dry paste is distributed in a form and com¬ pressed to a thickness of 15 mm. The cement is cured for 10 day at room temperature and 100% relative humidity . The resulting sheet has a dense structure and a smooth surface, and it is wate repellent and nailable. Example 6. Treatment of glass wool and rock wool with aluminum oxide stea¬ rate and preparation of a fiber cement sheet with the treated fibers . 200 g white glass wool are dried to a constant weight at 80°C, whereafter the glass wool is moistened with a solution of 2 g alu¬ minum oxide stearate (2,8 g Moaco C-14-70) in 1,6 liters of white spirit. The moistened fibers are left for 48 hours at 30°C and then dried at 60°C. The impregnated glass fibers are of a character completely dif¬ ferent from that of the starting glass fibers, as they seem "cotto like" and much softer, as well as they do not have the normally pricking character when touched as have the starting glass fiber Thereafter a fiber cement sheet is prepared, having a content of 12% of the treated glass fibers and 88% of super rapid cement. 48 g of the treated glass fibers are defibrated in 2 liters of wate in a blender. The defibration is perfect and no fiber lumps, whic occur when trying to defibrate the corresponding untreated glass fibers , are detected. Then 352 g of cement are admixed, and the slurry is diluted to 10 liters . After flocculation by admixture of 50 ml of a solution of Prodefloc Cl (1/4%), a sheet is formed by filtering off the water on a laboratory sheet former. The drained water is absolutely clear, which shows that the retention is com¬ plete. The filtration is performed on a 40 mesh wire cloth . The filter cake is compressed to 8.5 mm, and thereby also surplus of water is removed. The sheet is cured by storing for 7 days at room temperature and 100% relative humidity. The sheets produced show a low porosity and an extremely uni¬ form distribution of the fibers in the cement matrix in microscopy . The test is repeated in completely the same manner using 200 g of Rockwool ® batts , a commercial quality which has been treated • with oil and phenol resin in a conventional manner. However, a ® drying treatment of the Rockwool fibers was not carried out be¬ fore the impregnation with aluminum oxide stearate . In the above Examples , wherein cement has been used, each of the examples have been carried out with Blaine figures of about 2800, about 3200, about 3600, and about 4300, respectively. Using the low Blaine figures a considerably faster dehydration time is obtained than using the high Blaine figures . Example 7. - - - Treatment of cellulose fibers combined with defibration in a hammer mill. A hammer mill equipped with a feeder with adjustable feeding rate designed for supplying cellulose pulp in the form of webs is used for the treatment., an application device for the treatment medium having been placed immediately in front of the feeder. The appli- cation apparatus is an "Air-Less" flat spraying nozzle mounted in such a distance from the pulp web that the fan-shaped jet just moistens the web . The supply of treatment medium is controlled by adjustment of the dosage from the nozzle and the rate of pulp supply. Using the above arrangement two types of modified cellulose fibers are prepared: 1. 5% aluminum oxide stearate is added to 2500 g sulphate cellulo by spraying a solution (50%) thereof in a solution consisting of equal parts of white spirit and petroleum. Before the treatment the cellulose pulp has been dried to constan weight at 50°C for 18 hours . After the treatment the resulting fibers are dried out for 12 hours at 9 " θ°C in a ventilated oven in order to remove the remaining the solvent. 2. A mixture of 4% aluminum oxide stearate and 4% liquid paraffin is added to 2500 g of sulphate cellulose. The admixture is carrie out by spraying a mixture of 1.67 parts by weight of aluminum oxide stearate in solution (60%) in white spirit and 1 part by weight of liquid paraffin, 10% by weight of this mixture being supplied to the pulp . Also in this case, the fibers are dried as described above before and after defibration . The admixture of the treatment chemicals is a considerable ad¬ vantage when carrying out the defibration process . This advan¬ tage especially appeared in that the treated fibers had a consi¬ derably smaller content of cellulose dust compared to the un¬ treated fibers - a fact that is observed immediately when hand- ling the fibers . Example 8. Examination of the effect of the treatment of cellulose fibers de¬ scribed in Example 7. The immediate effect of the treatment of the cellulose fibers is a reduction of the reaction of the cellulose fibers to water. This was demonstrated as follows : Paper samples with a sheet weight of 250 g/m were prepared by means of the generally known art for the preparation of paper sheets in laboratory sheet former, partly- from untreated fibers, partly from a mixture of 75% of treated fibers and 25% of untreated fibers , an admixture of untreated fibers being necessary in order to obtain a paper sheet with the necessary coherency for the imple¬ mentation of measurements . The measurements used are determination of the shrinkage of the - paper sheet, i. e. its longitudinal change at the transition from completely moistened to dry condition. The results of this examination are as follows : Untreated fibers 4.8% shrinkage Fibers with 5% aluminum oxide stearate added 1.7% shrinkage Fibers with 4% aluminum oxide stearate and 4% liquid _ paraffin added 1.1% shrinkage It appears that the shrinkage of the paper has been considerably reduced as a result of the treatments ; the measured shrinkage is mainly to be ascribed to the presence of the untreated fibers . Example 9. Examination of treated cellulose fibers as fiber reinforcement in a cement matrix. The modified cellulose fibers described in Example 7 are used in these examinations . The following composition and preparation method are used in the fiber-cement experiments : Composition : Cellulose fiber 16 g 6.78% by weight Cement powder 220 g 93.22% by weight Water 400 ml i. e. a water/ dry matter ratio in the mixture of 1 The amount used corresponds to one sheet with a dimension of 200 x 80 x 8 mm 3 . • Process : A "Braun" blender with 3 speeds is used as mixing machine * Cement and water are mixed, whereafter fiber is added within 1 minute, and the mixing is continued for 2 minutes. A flocculation agent, 10 ml of a solution (0.2%) of Prodefloc Cl, is then added, and the mixing is continued for a further 0.5 mi nute. The mixture is transferred to a filter box with the length/width dimensions of the sheet to be obtained. After filtering off the water the filter cake is transferred to a form and compressed to the final thickness without further draining of water. It was not that the filtered water is clear without contents of cement partic The compressed sheets are cured at room temperature and 100% relative humidity for 2 weeks, whereafter the sheets were air dr The bending strength of the produced sheets was examined in both air dried condition and wet condition, the wet condition bei obtained by immersing the air dried sheets in water for 48 hour The results of the test are as follows : -B Type of fiber Bending strength kp/cm Dry condition Wet condition Untreated 220 105 5% aluminum oxide stearate added 225 130 4% aluminum oxide stearate + 4% liquid paraffin added 230 150 It appears that the treatment of cellulose fibers has an effect which, as expected, especially appear by the obt inment of higher ben¬ ding strengths of sheets in wet condition.

Claims: Claims . 1. Fibers in discrete form or in the form of fiber bundles, wood chips or shavings characterized in that they have-, in substantial 5 dry form, been treated with a metal oxide acylate. 2. Fibers as claimed in claim 1 characterized in that they have been treated with an aluminum oxide acylate or a titanium oxide acylate . ° 3. Fibers as claimed in claim 1 or 2 characterized in that they are inorganic fibers . 4. Fibers as claimed in claim 3 characterized in that they are sy 5 thetic mineral wool fibers . 5. Fibers as claimed in claim 1 or 2 characterized in that they are dry- defibrated cellulose fibers . 0 6. Fibers as claimed in any of the preceding claims characterized in that they are cellulose fibers treated with a combination of a water vapour barrier layer such as a wax, a paraffin or a polym and a metal oxide acylate . 5 7. A process for preparing metal oxide acylate-treated fibers cha terized in that fibers in substantially dry form are contacted wit a metal oxide acylate, and the contact is maintained during such a period of time and under such temperature conditions that a reaction between the metal oxide acylate and the fibers occurs . 0 8. A process as claimed in claim 7 characterized in that the fiber are cellulose fibers which are treated with metal oxide acylate simultaneously with their being dry- defibrated. 5 9. A process as claimed in claim 7 characterized in that a cohere cellulose fiber material in substantially dry form is treated with metal oxide acylate and is defibrated immediately thereafter or later . 10. Use of fibers as claimed in any of the claims 1 - 6 in compo¬ site materials .

Inventors: HOLBEK K
Applicants: HOLBEK K, INOVADAN KS
Application year: 1979
Main classification: C04B31
IPC codes: B27K5, C08L7, D06M11, D06M13, D06M101, D21H13