LU83303A1 - BUILDING MATERIAL MIXTURE, AND METHOD FOR PRODUCING PRODUCTS, ESPECIALLY MOLDED BODIES OR MOLDED PARTS, THEREOF - Google Patents

Description

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Demande de brevet BL-3126 / EM / mg de ........ 4/17/1981

"............." 'I · I · V

Désignation de l’inventeur O Le soussigné ........ Ernest Meyers .., ing, .cQn.s ... ..en. ..propr. «Ind .............................................

46, rue du Cimetière, Luxembourg agissant en qualité de déposant - de mandataire du déposant -

(2) ... la ... soc. ». Di.te.i .... E.TEENIT-.WERKE ... LUDWIG HATSCHEK ... AKTIENGESELLSCHAFT

4840 Vöcklabruck, Autriche (3) de l’invention concernant: .Eausto, ffmisçhung ,,, and..VerfahEen. For ... creation ... of products, .....

in particular of moldings or molded parts, from which désigné comme inventeur (s): 1. Nom et prénoms Dr. Klaus Weinrotter__________________________________________________________________ _________________

Address ..... Edisonstrasse, 3, ..4-840 Vöcklabruck, -Autriche ------------------------------- 2. Nom et prénoms Dipl.Ing ...... Günter ... Has 1 inger ............................. ...............................................

Address Flurweg 7, 48 60 Lenzing, Autriche 3. Nom et prénoms Director Prof ...... Dr ...... Hans Krassig ................... ..........................................

Address ..... Auss.ichtsweg 14, 48 63. Seewalenen, Autriche ................................. ....

'Il affirme la sincérité des indications susmentionnées et déclare en assumer l'entière responsabilité.

.............. Luxembourg ...... each 17 .4..1.9El .. 19 - (signature) A 680 26__________ (1) Nom. Prénoms, firme, adresse.

(2i Nom.Drenoms et adresse du déDosani.

-. Priority claim for a patent application ï filed in Austria on April 21, 19SO under _ No A 2133/80 3%

PATENT APPLICATION

ETERNIT-WERKE LUDWIG HATSCHEK AKTIENGESELLSCHAFT

^ 4840 Vöcklabruck

Austria j Building materials, and process for the production of products, in particular molded bodies or molded parts, therefrom · 1 t '1

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The invention relates to a new building material mixture for the> production of fiber-reinforced binders, in particular 1 cement-containing or -bonded, preferably increased i - <strength-exhibiting products, in particular for the manufacture of moldings or molded parts', and a process for producing these products from this building material mixture . The building material mixture according to the invention contains fibers based on 1 polyacrylonitrile and, preferably inorganic, hydraulic, binders as essential constituents and optionally additives. The new building material mixture makes it possible to produce and to make starting mixtures with an increased binder-f retention capacity (ttRetentionB)

Moldings with high strength, especially with increased bending tensile strength, to be processed.

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It is generally known that seven asbestos fibers are very good in combination with hydraulic binders and that the molded parts made from them, such as pipes, plates or sheets, have been known construction products for decades. In addition to that, such products preferably include The main constituent of cement contains, for example, about $ 10 asbestos fibers, which fulfill a double function: during production they serve as filter and

Ij retention agent for the binder and lead to high [!

Binder retention and in the finished product represent the ideal reinforcement component.

However, asbestos is a natural product and as such is not available indefinitely. As a result of this 1, a shortage of this raw material and cost increases can be expected in the next few years.

, j Considerations and attempts have already been made repeatedly from this situation, asbestos fibers | to be replaced by suitable substances. For example, cellulosic] see fibers have been proposed, although as Retentior.

j can serve as aids, but do not have the full strengthening properties of asbestos fibers.

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There are also experiments with artificial mineral fiberx

I like e.g. Glass fibers, known (DE-AS 2 409 216, DE-AS 2 622 465) t which have very high strength and a high modulus of elasticity, but are difficult to incorporate and cause difficulties due to the low alkali resistance.

I have tried with carbon fibers or Borfasera! Although mentioned, to date, however, only sparse earnings are £; 'became known, the cost factor of this high quality j ^ r

Special fibers certainly plays a major role.

AT-PS 355 ^ 86 describes a mixture for the production of, in particular plate-shaped or tubular, shaped bodies, in which hydraulic binders, haters and synthetic fibrids made of polymers such as polyethylene, polypropylene, polyacrylonitrile, polystyrene, polyvinyl alcohol, polyvinyl chlorides, polyamides or Polyster can be used. In fact, the use of these non-fiber fibrids causes binder retention on the order of asbestos and an increase in flexural strength, which, however, does not reach the vertebrate level of asbestos.

In GB-PS 1 130 612, DE-OS 2 063 933 and DE-OS 2 819 79½ possibilities of using highly stretched polypropylene fibers are described. Apart from the problems of integration due to the smooth surface of these fibers, there are processing difficulties due to the low density of the material, which leads to floating during processing.

DE-AS 2 850 337 describes a fiber cement material in which a polyvinyl alcohol fiber (PVA fiber), ie not a polyacrylonitrile fiber (I&C fiber), is used as the reinforcing element. The properties of polyvinyl alcohol fibers and PAC fibers differ greatly in both chemical and physical terms.

According to this DE-AS, the fiber titer of the polyvinyl alcohol fiber should be 1-5 dtex and the fiber should have a modulus of 1.27½ N / dtex (= 12.7 cN / tex) or I above. The fiber strength down there is clearly limited to 1 dtex, which is absolutely necessary due to the relatively high water solubility of PVA: namely, if PVA fibers present in a cement matrix have a higher fineness, they would not be able to reinforce them in the finished molded part Exercise more because there are very fine fibers, these fibers due to their very high surface area, relative to their volume, in the manufacture of the cement suspension with water at least i; partially go into solution. 'Fine i PVA fibers can therefore improve the properties of the fiber-> i! j Cement as a result of its fiber fineness, as it does; “Are at least partially dissolved, not at all achieved! will. The polyvinyl alcohol fibers provided according to DE-AS cannot therefore be used in any fineness.

j DE-AS 1 239 255 relates to a deep drilling cement mixture, Ί 1 in which polyacrylonitrile fibers or w-copolymer "-polyacrylic; nitrile (PAC) fibers are contained. According to this DE-AS, the fiber diameters should be 0.025 mm to 5 µm This | jj range of fiber fineness corresponds to 3 * 3 dtex - 666 dtex, j | there are relatively coarse fibers here, too. This DE-AS completely lacks an indication of the strength and elongation of the iS fibers used · L • i «i | The same applies to DE-OS 2 128 935 as I did for DE-AS 1 239 255 by the same applicant. The fiber fineness spectrum is also in l | relatively high range of 3.3 - 666 dtex.

• ^ In GB-PS 1 089 hhZ the use of poly-acrylic fibers for building material mixtures for the production of molded articles is only mentioned generally. Information about certain I Li j! · '; Fineness, strength and elongation values of the fibers ’*" S- are not included there. In Example 1 there, an individual fiber thickness of 3 denier, which corresponds to about 3 »3 dtex, is mentioned for a polyamide fiber (nylon).

In GB-PS 1 4o4 755, in addition to fibers made from an organic polymer - PAC fibers are not mentioned there - a non-fibrous ir 'polymeric material is required as a mandatory second component, the fiber i finenesses disclosed there of 2-5 den correspond to approximately j 2.2 - 5i5 dtex. This GB-PS also does not contain any information about the strength and elongation values of the fibers used there.

| j Finally, GB-PS 1 429 1 ^ 7 sees the use of preferably "organized" mixtures for building material mixtures, i.e. j: l e.g. Polyacrylonitrile

Fibers before, and according to this PS, two classes of fibers, namely those with water absorption and those with non-water absorption properties are mandatory each other. Details regarding

Fineness, strength and elongation values of the fibers are | also not to be found in this GB-PS. 1

From our own considerations, especially r to achieve higher strength values from fiber-containing; Building material mixtures to produce products within the scope of I 'of this invention tried particularly fine and solid I

To use polyacrylonitrile fibers, modacrylic fibers and / or fibers based on a polymer mixture of polyacrylonitrile or a starting copolymer based on a modacrylic fibers with a foreign polymer as reinforcing elements in the mixtures mentioned at the beginning. Polyacrylonitrile ^ or (co) polymers based on polyacrylonitrile have I; ----! Favorable properties for use in binder-containing, in particular cement-bound products, in particular good "alkali and acid resistance, low moisture absorption, excellent light and cousine resistance and rot resistance. Furthermore, as can be seen from FIG. 1 of the drawing, the surface of especially fine fibers j on the basis of polyacrylonitrile are well structured per se and thereby ensure better integration into the! i binder matrix than is the case with products with a smooth jj 1. The surface structure is formed by, for example, approximately parallel to one another on the circumference of the single fiber slightly oblique to the axis, closely spaced longitudinal grooves, which allow anchoring in the binder matrix, for example in the manner of a similarly structured structural steel. The density of these fibers - depending on the comonomer content, if any - is of the order of magnitude

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M 1.10 g / cnr and therefore does not cause any flotation problems during processing.

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Apart from these advantages, it has now surprisingly been found that fine-titer fibers based on acrylonitrile / i (co) polymers, or fibers based on this with a substantial proportion of very fine-tipped fibers, have extraordinarily good reinforcing properties in binder-bound, in particular cementitious Own products.

13 This result was not expected from the start. Some essential properties of asbestos, polyacrylonitrile fibers and cement are compared with each other, as shown in Table 1: jj -6-

Table 1

Comparison of some properties of asbestos, polyacrylic fibers, cement

Asbestos polyacrylic cement fibers ✓

Strength (lO ^ N / cm2) 30 3 - 5 0.08 modulus of elasticity (106 N / cm2) 16 0.03 2 -3

Fiber diameter Çum) 0.02-0.0¾ 1 dtex çÿ 10 jam

In order to achieve a reinforcement effect in the usual sense, it would have been expected that the modulus of elasticity of the polyacrylonitrile fibers would have to exceed the vert of cement, ie that the force-strain line of the reinforcement fibers would have to be steeper than that of cement. this is not achievable in the best villas with polyacrylonitrile-based fibers.

Contrary to these theoretical expectations, it was surprisingly found that through the use of polyacrylonitrile fibers, modacrylic fibers and fibers based on a polymer mixture of polyacrylonitrile or a modacrylic fiber on the basis of certain fiber finenesses and fiber strengths, a starting copolymer with a foreign polymer in a mixture with, in particular hydraulic, binders and optionally other mixture partners, the tensile strength of cement, which is

Test sheets is about 7N / mm, "can be increased to 2 to 4 times this verte. It is obvious that the reinforcing effect when using the particularly fine-tinted polyacrylic fiber arises from the fact that -7 - / i! which is enlarged for a work necessary for breakage, in that the fine fibers counteract widening of microcracks present or arising in the cement matrix.

The invention accordingly relates to a building material mixture for producing fiber-reinforced binders in particular cement-containing or -bonded, preferably I increased strength products, in particular for! Production of moldings or molded parts, which mixture j fibers based on polyacrylonitrile and, preferably! | "Inorganic, hydraulic, binders as essential | j contains constituents and optionally additives, which is characterized in that it consists of polyacrylonitrile or

Modacrylic fibers or fibers based on a polymer-tj mixture of polyacrylonitrile or a modacrylic fibers |; underlying copolymer with a foreign material! ! polymer each with individual fiber titer of 0.1 to 2 dtex, li in particular 0.2 to 1 dtex, and fiber strengths of

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1 20 to 60 cN / tex, in particular from kO to 55 cN / tex, at

Fiber elongations from 30 to 5, in particular from 15 to 8 96, and the binders, such as e.g. Cement, lime, gypsum, piaster, I alkali silicates and / or alkali aluminates, and if necessary, • j additional mixing partners, such as e.g. synthetic, organic, optionally fibrillated, fibers, and / or synthetic, organic fibrids, in particular based on polyalkylenes, polystyrene, polyvinyl alcohol, polyvinyl esters, polyamides and / or polyesters, and / or 4 fibers, and / or fibrids based of cellulose or cellulose derivatives, as well as any other, in particular; fibrous, inorganic additives, in particular slag fibers, basalt fibers, asbestos fibers, ceramic fibers,

Glass fibers, carbon, boron and / or silicon fibers, and if necessary the water intended for mixing, exist ·! 1.

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Basically, it should be noted at this point that the fibers contained in the building material mixtures according to the invention are in any case those that either come directly from a spinning process and the subsequent treatment process that may follow - the particular fineness is achieved when the fiber is drawn off with stretching, which, incidentally, can be demonstrated objectively - or those which are obtained from fibers of conventional fiber fineness obtained in a spinning process and, if appropriate, a subsequent after-treatment process, by subsequent fibrillating treatment, for example grinding.

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In the context of the present invention, "fibers" are generally filaments, single fibers, with the fineness specified above; but also, preferably loose, bundles or tufts of such individual filaments or fibers, and furthermore, extremely fine "fibrils" obtained from such (spun) fibers (usually not as high in fineness) by various treatment methods, in particular by grinding (Co) polymers or mixtures defined above.

In the fibrillating treatment, the spun fiber-forming macrofibrils or microfibril bundles formed from elementary fibrils and microfibrils, or oriented in the direction of the fiber axis, or the fibril strands built up by them, are detached from the association of the fibers and then form extremely fine fibers which isolate or, in loose association with remnants of the original (spun) fiber. 3 and b show such fibrillated fibers obtained by 90-minute fibrillating grinding in the Rieth-Hollaender from a (spun) folyacrylonitrile / polystyrene biconstituent fiber in 200-fold magnification. The extremely fine titre fibrils are clearly visible there. FIG. 5 shows a 200-fold magnification of -Ί -9- for comparison.

Chrysotyl - asbestos and there are clear structural similarities to the polyacrylic fibers according to FIGS. 3 and 4.

! 2 is also to be used for comparison. It shows!] That hitherto customary, highly stretched fibers have only been shortened in the first place, 1, but that fiber strands are split off, that is, fibrillation only to a very small extent

Measure takes place. It should be emphasized at this point that the fibers with the high finenesses used in the mixture according to the invention are not as described above, ’Produced fibrillated fibers are limited, but that fibers I obtained directly in a spinning process are also used according to the invention if they only meet the main criterion of the required fiber fineness.

I '· i i: The mixtures to be used in the mixtures according to the invention i I 'fibers are therefore structures which are characterized by a longitudinal extension which is pronounced relative to their width or thickness, which is one of the basic requirements for achieving p! which is high strength values.

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“Fibers” in the context of the invention are not to be understood as the “fibrids” which are oriented in two and / or three dimensions, have branched, tufted, tattered or flake-like structures and are obtained in a completely different way will. This fibrid i: i | have a multitude of extensions and / or depressions on their surface and their branched structure! attributable to an explosive evaporation of the solvent or by precipitation in a flowing medium with high turbulence.

As additives to the fibers to be used according to the invention, which are much finer in comparison to the prior art, however, such fibrids, that is to say which have no pronounced longitudinal expansion, can certainly be used, e.g. to achieve a particular increase in the retention of the binder in the production of molded parts from the building material mixture according to the invention.

With regard to the copolymers or (co) polymer mixtures which make up the fibers to be used according to the invention, the following is to be stated under MPoly- | j acrylonitrile fibers ”are synthetic in accordance with DIN standard No. 60001! To understand fibers, which by polymerization of a

Vinyl compound with at least 85 Gev .-? É vinyl cyanide! “(= Acrylonitrile) can be obtained. In addition to polyacrylic and nitrile fibers, so-called "modacrylic fibers" (see DIN standard No. 60001 or JSO standard 2076, (DAM 2) can also be used, which are also formed by polymerization and in the chain, however, are less than 85 gev. - $ 6, but more than 35% by weight, in particular more than 50% by weight, of acrylonitrile; i || groups. According to the invention, independently of the polyacrylonitrile fibers and iModacrylic fibers just defined, or Also in a mixture with them, such fibers are used which are formed on the basis of a mixture of, optionally copolymerized, polyacrylonitrile and a foreign polymer, that is to say essentially 4 so-called multi-component or multi-constituent fibers.

B The raw the off for the multi or biconsti | tuenten fiber-forming mixture of polymers is a p mixture of polyacrylonitrile according to the above DIN definition! and / or of "modacrylic" copolymer likewise according to the above DIN definition with a foreign polymer.

! § Polystyrene s! * J ’._ and furthermore polyvinyl alcohol, polyvinyl esters, in particular I“ 7y 1 X '1. * -11-' t s t * * t j I, polyvinyl acetate, cellulose esters, in particular cellulose! 2,5-acetate, polyurethanes, polyharas and polyamides.

Other possible premd polymers can be polyesters and vinyl or (meth) acrylic polymers which carry hydrophilic groups. The proportion of foreign polymer can be from 0.5 to about kO% by weight, in particular from 1.0 to 30% by weight, in each case based on the polyacrylic polymer which forms the fiber.

A building material mixture is therefore preferred in which the polyacrylonitrile fibers, modacrylic fibers or fibers based on a polymer mixture as defined above, in particular a polymer mixture in which the additional ί k 'spinable foreign polymer, in particular polystyrene, in amounts of 0.5 to 100 wt. - #, in particular 1.0 to 30 wt. #, 1 'and that the fibers in, in particular on the

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i * 2 to 15 times, stretched and in fibrillated form, preferably caused by I. grinding. In the production of the bi-consistency fiber a just mentioned, a mixture of two finished polymers, namely polyacrylonitrile and styrene, is fed to the spinnerets, which is otherwise objectively detectable on the finished fiber.

Ι As detailed tests with the J building material mixtures according to the invention showed, is the fiber binder! Composite; the more intimate and the reinforcing properties I are thus exploited, the better the titer i! «Is the single fiber. Usual polyacrylic fibers for textile I applications only have finenesses of at least 1.7 4 I to 10 dtex, they were therefore used * with only moderate success * for the production of binder-bound products. The high finenesses of the either directly spun \ to be used in the mixtures according to the invention or obtained by fibrillating treatment. Fibers

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! contribute to a substantial enlargement of the surface ί -12-! i i «, which also increases binder retention in the manufacture of the end products.

In-depth tests - it was recognized that the amplification effect can be effectively increased if the following is observed;

The steeper the stress-strain line of the polyacrylonitrile fibers present in the mixture according to the invention, i.e. The higher the fiber strength and the modulus of elasticity and the lower the fiber elongation, the more favorable the strengthening character. It is therefore important to adhere to the above-mentioned fiber strengths for the specified fiber elongations, i *

The fibers, based on ✓ made of polyacrylonitrile, as defined above in detail, are used to achieve particularly high strengths from those made from the building material mixtures

Products advantageous in cutting lengths from 0.2 to 20 mm,

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| preferably 4 to 15 now, used, the fibers il either by a defined short cut or by targeted • i | Grinding can be made. If the cut is too long

Under certain circumstances, processing problems I can arise due to the formation of knots and braids on the agitators, 1 if the cutting lengths are too short, the fibers can be knocked out. Partially lose strengthening character.

-] As already indicated above, it has proven to be very advantageous that the polyacrylonitrile or modacrylic fiber used in the building material mixture is already in! Course of fiber production after leaving the actual i | To stretch the spinning device very high, preferably to $ 2-15 times, after which the fibrillating grinding then follows in particular. The fibrillating - t! ability is a co-spun foreign polymer, 'T>! '--Ti jj ^ -13- i'; j i j preferably polystyrene, to a weight saute il of 0.5 to hO, in particular 1.0 to 30% based on fibers containing polyacrylonitrile, very high. Such polyacrylonitrile — multi-constituent fibers spit at one; '' mechanical treatment, especially grinding process, e.g. in a Rieth Dutch or refiner, particularly easily and finally develop both the desired in the finished product obtained from the building material mixture; reinforcing properties as well as the asbestos-like binder retention properties in its manufacture.

The fibers produced by a dry or wet spinning process, optionally aftertreated by fibrillation, give the end products particularly good reinforcing properties if their proportion in the mixture is 0.1-30% by weight, preferably 0.7-15% by weight. is. The optimal proportion by weight depends on the mixture partners and can be determined by short test trials.

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As has been shown, it can also be advantageous if the polyacrylonitrile fibers used in the mixture, as defined above, are softened in the course of the fiber production (the spinning process). By Ί. Finishing runs of 0.1 to 2% by weight, based on fiber, j have been shown to achieve a better distribution, which j ensures better incorporation into the end product. The

Finishing agents preferably have an ionic character and are essentially those which are customarily used in the production of: synthetic fibers for textile uses.

Examples of these are carboxylic acids or their salts, sulfated oils or fats and / or soaps. Furthermore can

Ij j be provided that in the mixtures in addition to the mixing partners, polyacrylonitrile fibers and binders, and! optionally water, inorganic as further additives; i -14- \ i fibers, e.g. Slag fibers, basalt fibers, asbestos fibers, ceramic fibers, glass fibers, carbon,

Boron and / or silicon fiber, synthetic fibrids based on polyalkylenes, polystyrene, polyvinyl alcohol,

Polyvinyl esters, polyamides and / or polyesters, as well! , j optionally cellulosic fibers and / or fibrids in fl I "amounts of 0.5 to 30 wt-9o, based on the total amount I of solids contained in the mixture.

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All in all, it should be noted that the great advantages of the use according to the invention of high-fineness polyacrylonitrile fibers as defined above, in particular in the surprisingly high retention force for the cement particles which are very important in the production of moldings, are that the building material mixture according to the invention can be processed without problems Plants previously only used for asbestos cement production, and also in the fact that these extremely fine parts of the polyacrylonitrile fibers - usually there is a fiber spectrum - in the finished product, formation of microcracks, which often only takes years to reduce their disadvantageous, strength-reducing properties Develop effect, hold back. The advantageous properties of building material mixtures according to the invention

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gene manufactured products such. * in comparison to cement | containing synthetic fibers with coarser titer Mixtures can therefore not be based on the 28-day strength s p or other conventional test methods with a relatively short | Test periods can be determined.

At this point, in addition to the testing of the physical characteristics of such fiber-reinforced products, it should also be noted that a comparison of data 1 with regard to strengths using such i; É i fiber-reinforced building material mixtures obtained test bodies -15 'i i * i, e.g. between those of the prior art and those according to the invention is usually not easy, since in this field the conditions for the production of the test specimens are not standardized and are therefore different in each case and therefore a conversion of the values obtained in 5 different ways is practically not can be done *

With regard to the processing of the abovementioned mixtures i into the end products, it was found that essentially all those methods can be used which also; are common in the processing of fiber-reinforced cement.

The process according to the invention for processing the 1 new mixture, for example to give moldings or molded parts, is basically characterized in that first of all the polyacrylics, as defined in detail above! nitrile fibers and any other desired t; Mischurg saves with the mixing water and the hydraulic | Binder to be mixed. The further processing | steps correspond to those which are common for asbestos cement and are assumed to be known. So how can li

A mixture of dewatering and shaping obtained as described above, in particular when applied to a sieve belt! or a sieve cylinder or the like. Furthermore, it can be provided that the polyacrylonitrile fiber or

t Mod ^ acrylfasem and the binder, as well as any other desired mixing partners, and the mixing water are converted into a suspension and processed by injection, injection molding, extrusion or casting into the desired shapes or parts to the end products. A processing method which is characterized in that the polyacrylonitrile fibers, as defined above, with the binder, ί t 4 · j! -16- if appropriate, the additives and, if appropriate, further mixture partners, are ground together, in particular wet, and that, if appropriate, a flocculant, in particular a polyelectrolyte, e.g. i on a polyamide basis (Separan, Dow) is added. During the joint grinding, it was found that an excellent fibrillation of the spun fibers and, furthermore, an extremely intimate mixing of the components is achieved which; Ensure particularly high strength in the end product.

In addition to these process steps, the shaped bodies or molded parts can also be pressed after shaping. In order to achieve a more intensive hardening of the products, this hardening can be done in Vasser at temperatures below 40 ° C

! respectively. According to another variant, the binder contained in the mixture can be hardened in air at temperatures between 40 and 100 ° C. Finally, the manufacture of the shaped bodies can also be carried out in such a way that the hardening of the mixture! Binder in an autoclave under pressure, in particular; 0.2-10 MPa, at temperatures from 100 to 180 ° C.

! Particularly dense products are obtained here.

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Example 1: 79 parts by weight of Vasser are mixed with 2 parts by weight of poly-acrylonitrile fiber, which has a single fiber titer of! 1.3 dtex, a strength of 3 ^ cN / tex and an elongation j] of 14 $ and an average cutting length of 2 mm,

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! mixed in a mixing vessel and then mixed with 19 parts by weight of Portland cement with stirring. This suspension is filtered off in a rectangular shape over a metal sieve, pre-dewatered under slight pressure and pressed at 10.0 MPa. The fiber cement / test plate pressed in this way is cured at a temperature of 23 ° C. above -17-. · I: * with a period of 28 days in air. From the tile | the bending tensile strength and the binding agent retention are then determined via the dry weight. 2 i | Result: bending tensile strength ï 13.5 N / mm jj binder retention: only jk * j / o, ί • I.

Ï Example 2:! Ä 78.4 parts by weight of water are mixed with 0.9 parts by weight

Polyacrylonitrile fibers, which have the same properties as described in Example 1, but have cutting lengths of 6 mm, and 1.9 parts by weight of polyethylene fibrids are mixed in a mixing vessel and then mixed with 18.8 parts by weight of Portland cement. The suspension is further treated as described in Example 1. The fiber cement test platelets pressed under pressure show a bending tensile strength improved by 22 $ compared to example 1 and a binding agent retention of 98 j ï Example 3î Ï 5OO parts by weight water with 10 parts by weight? Polyacrylonitrile fiber, which have a single fiber titer of • n I 0.6 dtex with strengths of 33 ° N / tex, elongations of 12 1 $ i and cutting lengths of 10 bim, and-with 12 wt.

Parts of ground wood are mixed in a mixing vessel and then mixed with 120 parts by weight of Portland cement with stirring. The suspension is, as described in Example 1, * 'i ·! treated further. The fiber cement test platelets pressed under a pressure application had a bending tensile strength improved by 3 ^ in comparison to Example 1 and a binder retention of 97 9 ^.

Example ki 'J 500 parts by weight of water are mixed with 6 parts by weight of poly i Ί i! -18-! ! acrylonitrile fibers, which have a single fiber titer of 0.8 dtex with strengths of 53 cN / tex, elongations of $ 13, and cutting lengths of 12 mm, and with 20 parts by weight of acrylic fibrids in a mixing vessel and then stirred with 120 wt. -Share Portland-, cement spiked. The suspension is further treated as described in Example 1. The fiber cement test platelets pressed under pressure of 1 t had a bending tensile strength improved by approximately 50 9 ° and a binder retention of 98 * 5 5 »compared to Example 1.

Example 5 * 400 parts by weight of water are incorporated with 8 parts by weight of plastic-acrylonitrile fiber based on polyacrylonitrile, in which 20 parts by weight of polystyrene are incorporated and which are subjected to fibrillating grinding in a Rieth-Holländer for 30 minutes had been, and mixed with 12 parts by weight of ground wood in a mixing vessel and then mixed with 120 parts of Portland cement. The I; Suspension is treated as described in Example 1. The fiber cement test coupons pressed under pressure exhibited about $ 65 improved flex tensile strength and $ 97 binder retention compared to Example 1.

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Claims (8)

2. Building material mixture according to claim 1, characterized in that it contains cut lengths of 0.2 to 20 mm, preferably from k to 15 mm, present, obtained by defined short cut or by grinding, as defined in claim 1, polyacrylonitrile fibers. 3. Building material mixture according to claim 1 or 2, characterized in that the polyacrylonitrile fibers, modacrylic fibers or fibers based on a polymer mixture as defined in claim 1, in particular those fibers based on a polymer mixture as defined therein, in which the additional spinnable foreign polymer, in particular polystyrene, in amounts of 0.5 to 100 wt.%, in particular 1.0 to 30 wt fibrillated form caused by grinding. «K. Building material mixture according to one of claims 1 to 3 »'fc (characterized in that it is obtained in amounts of 0.1 to 30% by weight, preferably 0.7 to 15% by weight, as defined in claim 1, polyacrylonitrile fibers on the total amount of solids in the mixture. 5. Building material mixture according to one of claims 1 to h, characterized in that the polyacrylonitrile fibers, as defined in claim 1, for improved integration into the end product, preferably ionogenic additives, for example 'carboxylic acids or their salts., Sulfonated oils or fats and / or soaps. 6. Mixture according to one of claims 1 to 5, characterized in that in addition to the mixing partners, as defined in claim 1, polyacrylonitrile fibers and binders, and optionally water, inorganic fibers provided as further additives, such as e.g. Slag fibers, basalt fibers, asbestos fibers, ceramic fibers, 1 Z --- -ÄA glass fibers, carbon ^ boron and / or silicon fibers, synthetic fibrids based on polyalkylenes, polystyrene, polyvinyl alcohol, polyvinyl esters, polyamides and / or polyesters, as well as, optionally cellulosic, fibers and / or fibrids in amounts of 0.5 to 30 wt based on the total amount of solids are contained in the mixture. 'IJ 7. Process for the production of moldings or moldings from at least one mixture according to one of claims 1 to 6, characterized in that first of all the polyacrylic as defined in claim 1! I nitrile fibers and the binder, as well as optionally any further mixing partner desired, and the | Mixing water are mixed, after which this mixture j a drainage and shaping, especially under s | . Application to a sieve belt or a sieve cylinder or the like. Is subjected. ;1 ; I: I 8. Process for the production of moldings and / or molded parts from at least one mixture according to one of Claims 1 to 6, characterized in that the like! 1, | Polyacrylonitrile fibers defined in claim 1 and the I ί binder, as well as any desired desired J further mixing partners, and the mixing water are converted into a ί suspension and sprayed, injection molded, Extrude or cast into the desired body or part. 'Ä 9. Process for the production of moldings and / or 1 moldings from at least one mixture according to one of the claims 1 to 6, characterized in that the polyacrylonitrile fibers as defined in claim 1, with the binder, optionally the additives and, if appropriate, V-3 (1 - optionally further mixture partners , together, preferably in a Dutch mill or refiner, in particular wet, and that, if appropriate, a flocculant, in particular a polyelectrolyte, for example based on polyamide (Separan, Dow), is finally added immediately before processing the mixture thus obtained I si 10. The method according to any one of claims 7 to 9, characterized in that the mold body or molded parts are additionally pressed after the shaping. j j - 11. Method according to one of claims 6 to 9 »| characterized in that the hardening of the in the mixture »-. contained binder in water at temperatures below h0 ° C. ί j 12. The method according to any one of claims 7 to 9 »j. characterized in that the hardening of the mixture | contained binder in air at temperatures! between 40 and 100 ° C 13. The method according to any one of claims 7 to 9 », characterized in that the hardening of the in the mixture; contained binder in the autoclave under pressure, in particular from 0.2 to 10 MPa, at temperatures of 100 to 180 ° C. ——------! '/ i: Si ||