NO884994L - PROCEDURES FOR THE MANUFACTURING OF BODIES, SPECIFIC BUILDING ELEMENTS OF HYDRAULIC BOND, ASSOCIATED MATERIAL MIXTURES AND THESE SUPPLIES OF REINFORCING FIBER, AND PROCEDURE FOR PRODUCING PLASTIC FIBERS WITH RUGJORT. - Google Patents

Description

The invention is based on a method for the production of bodies, in particular building elements of hydraulically bound, hardened material mixtures and reinforcing fibers added to these. The object of the invention is also a finishing technology for roughened plastic fibers.

Disadvantages of the bodies formed from material mixtures produced with hydraulic binders, for example cement or plaster, such as for example concrete elements, plasterboards and similar products, are their brittleness, their susceptibility to scratches, as well as their tensile strength which is significantly lower than their compressive strength . To remove these disadvantages, concrete steel inserts, so-called armatures, are normally used, which, however, do not avoid the negative phenomena that can be traced back to the material's brittleness, namely the appearance of cracks, for example shrinkage cracks, the damage caused by impacts, notches, cracks, etc.

To prevent brittleness, reinforcing fibers are usually added to the raw hardening mixture. These fibers form, in contrast to the generally concentrated concrete steel reinforcement, a relatively dense and evenly distributed reinforcement throughout the body. In this case, the reinforcement is thus a fine fiber skeleton, which can be ensured with the help of the mixing of fiber cuts which gives an even distribution in the hydraulically bound hardened material.

The fiber-reinforced mixture is produced by using fibers of a wide variety of substances. The natural asbestos fibers have been used since a long time ago and to the greatest extent, but due to their relative shortness, the brittleness of the plates and bodies made of asbestos-reinforced mixtures will not be reduced to any significant extent compared to the materials without fiber reinforcement, even though their tensile strength significantly exceeds these.

Building elements are also known which are produced from hardened material mixtures containing thin, cut steel, glass and plastic fibers with high strength. The brittleness and cracking sensitivity of these building elements is indeed reduced, but an extensive application is however prevented in the case of steel fibers due to the corrosion, in the case of glass fibers on the other hand due to the damage to the fiber material that occurs due to the acidity of the cement.

The cut plastic staple fibers are not exposed to any corrosion risk, but their use is however associated with two fundamental problems: on the one hand, the even, clump-free mixing of the fibers in the matrix encounters obstacles, on the other hand, the embedding of plastic fibers that have hydrophobic properties are difficult to secure in the water-rich matrix, i.e. their binding without stretching in the hardened, i.e. solidified body.

The Even or uniform mixing of the plastic staple fibers is basically prevented due to the charging of the fibers with static electricity and the resulting sticking together. British patent no. 2,035,990 aims to remedy this problem, according to which the fibers are coated with an antistatic agent or that antistatic fibers are used as their material. According to US patent 4,039,492, the distributability of the fibers is ensured in the wet medium due to their surface hydrophilization.

German patent specification 28 16 457 discloses the use of plastic fibers with a hydrophilic character in a hydraulic binder mixture.

The essential part of the design solution described in Swiss patent 592,216 consists in mixing chopped fibrillated fiber stacks into the concrete. The uniform distribution of the fibers in the matrix is ensured by the fact that, as a result of the mechanical effects that occur during mixing, the fiber bundle is divided into elemental fibers and mixes the fiber pieces that are torn off in between in the matrix.

According to the Hungarian invention, application number 117/81, the pull-out-free embedding of plastic fibers in the hardened body is ensured by means of a previously applied transition layer on the fiber surface, while, on the other hand, as regards the Hungarian invention, application number 1766/83, it improves the binding in the matrix of the of foils cut and fibrous fibers in such a way that the fibrillation of the fibers is periodically cancelled.

The essential thing about the solution provided by British patent 2,025,841 is that during the production of plastic fibers the surfaces of the fibers are given bulges which actually anchor the fibers in the hardened material and thus prevent further slippage. The bulges occur during the manufacture of the fibres, which takes place by extrusion, as the base material for the fibers is a mixture of polyolefins with different softening points, respectively. that a thermosetting resin has been mixed into the thermoplastic polyolefin and that the fibers are produced from this mixture. Thus, the bulges are formed with the help of the non-plasticized fabric parts embedded in the softened material during production, and protruding from there. The heterogeneous material composition which causes the bulges, however, has serious shortcomings. The breaking strength of the fibers amounts to a maximum of 2700 kg/cm<2> (variable between 1.1-3.5 g/Denier values), and this value amounts to a total of only 60-70$ of the strength of the fibers of homogeneous material. To a similar extent, the modulus of elasticity is also reduced for the fibers that contain bulges, which in contrast to the value of approx. 40,000 kg/cm<2> which can be ensured by fibers of homogeneous material, only amounts to 11,000-26,000 kg/cm<2>. The decline of the aforementioned parameter is markedly shown by the lower efficiency of the fiber reinforcement, the reduction of the firmness of the hardened end product. A further disadvantage means the finishing technological constraint, according to which bulges can be secured on the surface only by producing relatively thick fibres. The fibers must have a thickness of 0.7-2.0 mm (in phase fineness expressed at 3400-9800 Denier), and this phase thickness is an order of magnitude (in terms of phase fineness index two orders of magnitude) greater than the thickness of the fibers with a smooth surface. At the same fiber dosage (fibre quantity), the thick fibers do not in any way ensure the fine distribution of the reinforcement in the mixture, which is necessary for an effective increase in blast and impact strength. The increase in the amount of fiber added is, on the other hand, limited due to the compressibility of the mixture, which due to the thick and thus stiff fibers is already adversely affected. The increase in the amount of fiber clearly also has an unfavorable economic impact.

From the outstanding designs, it follows that at the moment the problem-free reinforcement cannot be considered solved with hardened matrices (mixtures) made with hydraulic binder and with cut plate fibers (stack fibers). The fibers that have a smooth surface, which have satisfactory fiber-mechanical parameters, can certainly be mixed in the wet matrix, whereby, however, the utilization of their favorable mechanical properties in the hardened (hardened) final product is hindered due to their unsatisfactory anchoring, i.e. the sliding of the fibers. The fibres, on the other hand, which are provided with bulges that ensure corresponding anchoring, as a result of the fibres' unfavorable parameters, reduce the operating economy of the building part completion as a result of the fiber dosage that occurs forcibly in larger quantities, which at the same time also concerns the workability and compressibility of the raw the mixture has an adverse effect.

The invention has the task of enabling the production of end products, for example building parts, boards or similar geometric bodies of staple fiber reinforced, with hydraulic binder added, hardened mixture, of such good and uniform quality, in which a favorable uniform distribution is ensured which gives a fine fiber skeleton and problem-free grippy embedding of fibers that dominate optimal mechanical parameters.

The basis for the invention is the realization that in the case when, by maintaining the homogeneity of the plastic material in the fibers, the increase of the surface and the good embedment of the fibers in the matrix can be ensured, the production of a finely distributed fiber skeleton in the matrix of correspondingly thin fibers is made possible and as a result gives an end product that has preferred mechanical physical properties. Our further realization is that the elementary fibers that have the desired properties can be produced from plastic that contains filler formed from lntered small grains by stretching and rubbing, as a result of this work process part of the lntered existing near the surface of the fibers small grains are loosened and pulled out and where in their places spindle-shaped cavities are formed on the surface which also rule over torn small fibers, which effectively effect the embedment in the matrix fixed with hydraulic binder, while other small grains located along the surface remain also after rubbing effect embedded in the fibers, whereby however their surface is exposed and due to their nature ensures for the hydraulic binder preferred, significantly better bonding possibilities than the plastic.

Due to this recognition, the given task was solved according to the invention with a method, during certain stages a matrix is produced from hydraulic binder, aggregate material and water, this being mixed with plastic fibers and the mixture is allowed to harden or/and is hardened, possibly after its shaping , with the essential part of the method being that the matrix is mixed with plastic fibers which have a roughened surface which contains fillers formed by means of lignified small grains and by means of the tearing out of lignified small grains which lie along the surface. In this regard, it must be emphasized that the term "body" completed in accordance with this procedure is to be interpreted as broadly as possible, and extends alongside the most diverse forms of building elements, building parts and building panels, for example also to concrete surfaces with a leveling layer applied, even wall plaster and formless masses of material that fill voids, etc.

According to an advantageous implementation of the method, the plastic fibers are mixed in an amount of 0.05-20.0 by mass, preferably 0.1-1.0 by mass, to the matrix, relative to its dry, anhydrous mass. The length of the monofibres is generally 10-100 mm, preferably 20-60 mm and their diameter is 0.04-0.8 mm, preferably 0.1-02 mm. The monofibres are preferably filled with inert small grains of diameter 1-30 pm which consist of inorganic matter.

The monofibres generally consist of polyolefin, preferably of polypropylene and/or polyethylene and/or their mixtures and/or their copolymers.

Furthermore, it can be advantageous when the matrix is supplied with shaped plastic fibers which have a changeable cross-sectional shape and/or wavy plastic fibres. The fibers can contain flat-printed formations which are arranged, for example, at the same or substantially the same distance. The shaping that gives the fibers a periodic pattern can, for example, take place in such a way that, during fiber production, the still warm fiber bundle after thermofixation, which for example exhibits a temperature of 60-80°C, is passed through between fluted rollers, so that the individual fibers are thereby arranged regularly next to each other, i.e. arranged lying in one plane. As a result, the ribs on the rollers periodically leave indentations in the fibers to an equal extent, as a result of the cold flow. In the impressed places, the fiber thickness can even go back to 70$ of the original cross-section, i.e. the fiber is flattened, its cross-sectional area, however, remaining unchanged.

For a further implementation of the method, it is characteristic that bundles of plastic fibers are mixed into the matrix which are twisted and in their twisted state (in the twisted form) are fixed by applying heat.

The fiber bundles are expediently 15-70 mm long and twisted 90-360° about their geometric axis, preferably 180-270°.

All of the aforementioned phase types can also be made antistatic and/or hydrophilized.

The supply of the fibers in twisted (twisted) form, as well as in the form of fiber bundles, requires the uniform, clump-free distribution of the individual fibers in the matrix. The resolution or the division of it in the otherwise - undistorted - form added foil fiber bundle into individual fibers requires a great deal of mechanical work. This disadvantageously means an extension of the 1-2 minute long mixing process by 3-4 minutes, at the same time the amount of fiber that can be added is also relatively small, a total of only 1-2 kg of fiber/m<3>. The fiber bundle cut from the spinning of the monofilament (monofibre), on the other hand, easily falls apart during the mixing process under the influence of minimal mechanical work, and the individual fibers are distributed evenly in the matrix. In the case of the supply of the twisted fiber bundle, the increase in mixing time amounts to only 20-40 seconds and the supplied amount of fiber can even reach 10-20 kg per cubic meters.

The subject of the invention is also a method which serves for the production of plastic fibers with a roughened surface, with which fibers are produced from a plastic raw material f by stretching and drawing, the method being characterized by the fact that the fibers are produced from a plastic containing filler formed by of woven small grains and the woven small grains that have been loosened along the surface due to the fiber stretching are pulled out by the fiber due to the effect of rubbing and in their places and/or along these places, cavities are created which contain torn small fibers and - possibly - are the surface of the lntered small grains exposed by means of a tearing or rubbing process.

A usable plastic material for the production of such fibers which have such a roughened surface appears, for example, in Hungarian patent document no. 167,063.

The invention will subsequently be described on the basis of the attached drawing, which illustrates the type and method of production of the fibers used for the inventive method on a significantly larger scale than the actual size. Fig. 1 shows a piece of fiber in the state before the post-drawing work sequence, in side view. Fig. 2 shows a single fiber piece produced according to the off-finner method in the final state, in which the admixture to the matrix takes place.

The material of the fibers used for the method is a known in and of itself - inert polyolefin which contains lntered fillers. The filler of the polypropylene, polyethylene or linear polyethylene base material, for example, is a solid granular material, for example chalk powder or talcum, which exhibits an average grain size of 3 pm. In addition to the granular filler, the fiber base material generally also contains such elastomers and surfactants, which significantly improve the interaction between the small grains and the polyolefin matrix.

A known characteristic of the plastic material that is mixed with such a filler is that during the fiber production during the fiber extrusion and post-stretching process, the extent of stretching and the orientation of the macromolecules in the surroundings of the enclosed small filler grains is locally larger than in the rest of the material, which increases the breaking strength and the modulus of elasticity for the material as a whole, although the embedded lntered small filler grains reduce the usable cross-section of the fibers, which exhibit a thin diameter of approx. 100 - 200 pm. 1 fig. 1 is a piece of fiber produced from an excellent material shown in the state before the roughening and stretching process, and designated as a whole by the reference number 1. The length of the piece of fiber 1 is indicated by h, and its diameter by D. The lntered small grains 2 embedded along the fiber surface are visualized with dotted lines, and as can be seen, the fibers show bulges 3 along their surface where the lntered small grains are arranged.

If it is in fig. 1 showed fiber piece 1 further stretched, then this length h increases until a in fig. 2 showed length H, its diameter D being reduced towards d (H > h and d < D).

As a result of the drawing-stretching process, the small filler grains located close to the fiber surface, i.e. the inert small grains 2, loosen, and in their surroundings parallel (spindle-shaped) cavities arise on the geometric longitudinal axis x of the fiber 1, from which the small grains 2 easily can be removed with little effort. According to the invention, this force which removes the small grains is exerted by rubbing the fibers. Instead of the removed inert small grains 2, cavities (indentations) 4 and the polymer lamellae formed from layers of plastic material by fibrillation (see bulges 3 in Fig. 1) which previously enveloped the grains that existed instead of the cavities, remain. is further torn up as a result of the rubbing effect, at least so that on the surface of the cavities 4 or in their surroundings, grooves remain and shorter, respectively. longer small fibers 5, which then significantly increase the specific surface area of the fiber 1.

However, the inert small grains 2 arranged somewhat deeper in the vicinity of the fiber surface are not released under the influence of the stretching and rubbing, as they, however, separate over their existing bulges 3 (fig. 1), so that the surface of the small grains is exposed. These exposed surfaces of the small grains are in fig. 2 has been highlighted using hatching. On these exposed surfaces of the inert small grains 2, the hydraulic binder adheres significantly better than on the plastic material surface, so that these surfaces increase the hydrophobic properties of the entire fiber 1 and improve the chemical connection with the matrix.

The surface morphology of the fibers undergoes further changes during the mixing of the fibers 1 to the matrix, which means that the already favorable properties of the fibers are further improved. The tearing or rubbing effect on the small grains (cement, sand, pumice, etc.) in the matrix which is exerted on the fiber surface during the mixture and the shear and pressure effects occurring in certain types of mixture increase the fibrillation as a result of the fibrillation tendency of the fiber materials which extend partly thicker in the surroundings of the grains.

The mechanical parameters of the fiber produced in the previously described manner are as good or better than the fibers which have a smooth surface and are made of filler-free base materials, whereby the cavity system which is formed in an essentially even distribution on the fiber surface, secures the crystal molecules of the hydraulic binder, for example the cement, and fulfills the binding and the slip-free embedment of the fibers 1. The effectiveness of the binding is thereby also further increased, by the fact that the small fibers 5 (fig. 2) on the one hand can be incorporated and embed in the hydraulic binder and, on the other hand, that the exposed surface of the inert small grains (see shaded area in fig. 2) - as already mentioned - adheres significantly better to the hydraulic binder than the plastic material surface of the fiber 1. This fiber raw , in comparison with the initially described fiber types produced with bulges, over an approx. 100$ greater breaking strength and an approx. 50$ greater modulus of elasticity, which naturally also obviously entails more favorable mechanical and physical as well as profitability parameters for products manufactured using such fibers as well as the easier incorporation option for the raw mixture (matrix).

With the help of the suitable selection of the grains for the matrix and the mixing technology (mixing type), it will be achieved that the surface of the cut fibers containing the inert small grains is not roughened through the preliminary, prior to the mixing of the matrix carried out tear-off process, but even through the matrix-mixing process in desired extent. In these cases, the inert small grains located along the surface of the fibers are only pulled out of the fibers during the mixing of the matrix, and voids and small fibers are formed, and small grains are embedded in the fibers, which show exposed surfaces.

The invention shall be described in more detail by means of examples.

Example 1

According to the inventive method, 7-15 mm thick building elements for building facade cladding are produced. The matrix, i.e. the raw mixture, is prepared from 100 parts by mass of 350 PC cement and 200 parts by mass of sand with a grain size of 0-4 mm under the addition of so much water that the water/cement factor in the mixture amounts to 0.65. This matrix is fed with 3 mass parts of the 40 mm long cut product according to fig. 1 and fig. 2 with roughened surface and 0.15 mm diameter. The fiber cut material is fed to the matrix in the form of twisted monofilament bundles. The subsequent mixing is carried out for a period of 30 seconds and as a result the twisted bundles dissolve into individual fibers and distribute evenly in the matrix.

The mixture containing the fibers is incorporated into forms and caused to harden. The end product is tough, with high impact resistance, free of shrinkage cracks, in its consistency and exhibits a smooth surface, as well as a bending-breaking strength of 14-15 MPa.

For comparison, thicker plastic fibers provided with bulges on their surface and produced from heterogeneous plastic material were added on the basis of the matrix produced on the basis of the recipe according to the present example as described in the introduction of the description. In order to achieve a bending-breaking strength of 14-15 MPa, 15 mass parts of the fiber material must be added, i.e. five times the amount must be added, which is not only disadvantageous from an economic point of view, but also a lack of the corresponding material density, which further leads to follow the smooth workpiece surface.

Example 2

The leveling concrete base is produced according to the inventive method. The matrix is made from 100 parts by mass of cement material 350 PC, 200 parts by mass of sand, grain size 0-1 mm and added enough water that the water/cement factor amounts to 0.57. This mixture is fed with 3 mass parts of 25 mm long cut material of the inventive twisted monofilament bundles. The individual fibers are 0.12 mm thick. During a mixture that lasts 40 seconds, the twisted bundles of fibers are separated into individual fibers, and these are distributed evenly in the mixture. The mixture containing the fibers is applied to the concrete floor and allowed to harden. The impact resistance of the solidified leveling layer is high and the shrinkage cracks are not present. The flexural breaking strength of the layer is 13.1 MPa, with a toughness index of 11. If a matrix is supplied with the same composition of chopped plastic material fibers, which have the same cross-section and the same length as well as the same fiber strength and quantity, but which however do not contain any small grains and were not produced due to the method described in Figures 1 and 2, a final product with a bending-breaking strength of only 9.4 MPa is obtained, which is approx. 40$ lower than with the material produced according to the inventive method.

The advantage of the invention is that the mechanical and physical parameters of the end product which is made of fibers that have roughened surfaces are preferable, as there is present in the body a finely distributed optimally arranged fiber skeleton, whose individual fibers are securely and non-sliply embedded in the matrix. In this way, the special economic values of building element production are also better than a similar provision for the already previously known design solutions.

The invention is naturally not limited in any way to the previously presented examples, but can be realized in many ways within the scope of protection defined by the patent claims.

Claims (10)

1. Process for the production of bodies, especially building elements, during certain stages a matrix (a mixture) is produced from hydraulic binder, aggregate, to which plastic material fibers are mixed, and the mixture - possibly after its shaping - is hardened and/or allowed to harden, characterized in that the matrix is mixed with plastic material fibers (1) which contain filler which is formed from inert small grains (2) and which has a roughened surface due to the tearing out of the inert small grains (2) lying along the surface. 2. Method as stated in claim 1, characterized in that the plastic material fibers are mixed with the matrix in an amount of 0.05-20.0 mass, preferably 0.1-1.0 mass$, related to its dry, anhydrous mass. 3. Method as stated in claim 1 or 2, characterized in that the matrix is mixed with monofibres which have a length of 10-100 mm, preferably 20-60 mm and a diameter (thickness) of 0.04-0.8 mm, preferably 0.1-02 mm, and filled with inert small grains (2) with a diameter of 1-30 pm which consist of inorganic material. 4. Method as stated in one of claims 1-3, characterized in that the matrix is mixed with monofibres consisting of polyolefin, preferably polypropylene and/or polyethylene and/or their mixture and/or their copolymers. 5 . Method as stated in one of claims 1-4, characterized in that plastic fibers having a shaped, changeable cross-sectional shape and/or wavy plastic fibers are added to the matrix. 6. Method as stated in claim 5, characterized in that the matrix is supplied with plastic fibers containing flat-printed formations which are arranged from each other at the same or essentially the same distances, produced during production using cold flow pressing. 7. Method as stated in one of claims 1-6, characterized in that the matrix is mixed with twisted, and in its twisted state (in the twisted form) fixed plastic fiber bundles by means of heat supply. 8. Method as stated in claim 7, characterized in that the matrix is mixed with fiber bundles which are cut to a length of 15-70 mm and which are twisted about their geometric longitudinal axis by 90-360°, preferably 180-270°. 9. Method as stated in one of claims 1-8, characterized in that the matrix is supplied with antistatic and/or hydrophobicized plastic fibres. 10. Process for the production of plastic fibers which have a roughened surface, in particular for the reinforcement of bodies which are finished from post-hardening materials, during the course of which fibers are produced from a plastic base material by stretching and drawing, characterized in that the fibers (1) are produced from plastic material containing filler formed by inert small grains, and where the inert small grains (2) which due to the fiber stretch loosen along the surface are torn out by tearing/rubbing impact and where voids (4) are created in their places and/or along these places, which also contain torn up small fibers (5) and - optionally - that the surface of the remaining inert small grains (2) in the fiber is exposed by means of a rubbing process.