DK149428B - Process for the preparation of fibre-reinforced shaped objects - Google Patents

Description

149428

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing fiber-reinforced molding articles having a matrix of cured inorganic binder, first producing an aqueous pulp of reinforcing fibers and retention fibers containing a fiber dispersant, then producing an aqueous slurry of reinforcing fibers. inorganic binder particles and optionally other additives containing more water than necessary to ensure hydration of the inorganic binder by suspending the hydraulic inorganic binder particles and optionally other additives in the aqueous pulp, optionally with further addition of water, green moldings are produced by dewatering the slurry and the green moldings are cured.

The use of a variety of fibers in the manufacture of fiber-reinforced moldings, such as e.g. slabs for use as building materials are known. One of the most important examples of products of this type is asbestos cement products.

20 The most widely used methods for producing such products are the Hatschek and Magnani methods.

Common to these two methods and other less frequently used methods such as the Head Box method and the Fourdrinier method is that they comprise the three steps mentioned above: First an aqueous slurry of cement particles and asbestos fibers is prepared, then green molds are produced by dewatering by suctioning the excess water, and then the green molds are cured to the finished products, e.g. by curing, autoclaving or at room temperature.

30 The Magnani method works with a slurry having a relatively low weight to water ratio (hereinafter referred to as "w / t ratio"), usually of the order of 1-2. This rather thick slurry is placed directly on an endless filter cloth, and sheets of the desired shape are prepared by dewatering provided by combined suction and compression.

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The Hatschek method produces an aqueous starting slurry with a v / t ratio of approx. 2. Thereafter, the slurry is diluted by adding a quantity of water equal to approx.

5-10 times the volume of the starting slurry. The finished slurry is introduced into a Hatschek machine where the solid material is taken from a sludge bath by means of a rotary screen cylinder which transfers the material to a constantly moving filter cloth where the material is further dewatered. The material is then passed as a thin layer onto a rotating cylinder, called the format roller. When sufficiently thin layers are wound on the format roller, the material is removed as green sheets that can be molded and compressed prior to curing.

Asbestos fibers have special properties that make them suitable for these processes. Not only do they exhibit the good 15 reinforcing properties of the finished product, but they also exhibit excellent properties during the plate manufacturing processes.

However, various limitations in the use of asbestos fibers have necessitated the development of alternative fiber-reinforced materials which can be made on the machines used in the manufacture of asbestos cement products but which are reinforced with asbestos-free fibers. Various fibers have been proposed to replace asbestos fibers, e.g. glass fibers, steel fibers, and natural and synthetic organic fibers.

25 However, none of the attempts to replace asbestos fibers with only one type of fiber of another type have been completely successful.

Substantial problems often arise during the manufacturing process, since it has been difficult to provide an approximately homogeneous distribution of the fibers in the slurry; thus, both glass fibers, cellulose fibers and a variety of plastic fibers exhibit a marked tendency to clump together rather than spread evenly in the slurry. The tendency for lump formation to increase is especially due to the Falden-35 w / h ratio, increasing fiber concentration and increasing fiber length and elasticity. In the Hatschek method, an inhomogeneous fiber distribution in the finished slurry can be evidenced by the formation of clouds of higher fiber and binder particle density. These clouds cause problems during transfer to the rotary sieve cylinder.

Another problem occurs during the drainage, where e.g. glass fibers and most plastic fibers are unable to retain the binder particles, which is therefore sucked off together with the aqueous phase. This poor retention ability is also reflected in an inhomogeneous plate structure which, by the Hatschek method, can lead to delamination of the green or cured sheets. complicates subsequent shaping, and additionally, a tendency for moisture movement in the green plates, which can lead to the formation of microcracks already under the cure.

Finally, the quality of the finished product can become unsatisfactory. Thus, fiberglass reinforced cement sheets may exhibit good initial strengths, but due to chemical degradation of the glass fibers in the alkaline matrix, the strength properties often deteriorate catastrophically in a short time. Cement sheets reinforced with spun plastic fibers, e.g. of nylon or polyolefin, often exhibit poor strength, which is probably due to poor anchoring of the fibers in the matrix. Inhomogeneous fiber distribution can be found by the fibers protruding through the surface of the plates, resulting in reduced weather and frost resistance.

Furthermore, it has been proposed to improve the properties of the slurry by adding various additives such as organic flocculants, dispersants, wetting agents, thickeners and plasticizers.

This can eliminate certain problems, but often with the cost that other problems become more pronounced.

For example, it is possible to provide better binder retention by adding flocculants 35 to the slurry. In contrast, there is a risk of forming fine through-flow channels in the finished product, which results in poorer strength properties. Eg. it is proposed in GB Patent Application No. 2,035,286 to use a combination 4 149428 of finely divided silica-containing materials, preferably less than 10 microns, and a flocculant as a coating on glass fibers and in a slurry of cement particles and glass fibers to make of fiberglass-5 reinforced cement-bonded products with high strength.

Addition of organic thickening and dispersing agents may adversely affect the curing capacity of the hydraulic binder, thereby necessitating the addition of curing accelerators; but since the process water is recirculated for environmental reasons, it is difficult to keep the concentrations of these additives at the desired values.

When comparing the properties of asbestos fibers with the proposed replacement fibers, it is seen that the properties of asbestos fibers are special in at least three respects: First, the 15 asbestos fibers have a specific surface area that is far greater than most types of replacement fibers. Second, the asbestos fibers exhibit much greater variation in size than the replacement fibers. Third, the asbestos fibers have hydrophilic properties that far exceed most of the proposed 20 replacement fibers.

Presumably, all of these properties play an important role in the ease with which green asbestos cement slabs can be manufactured and handled.

Therefore, it has been proposed to replace asbestos fibers not with one, but with two types of fibers, reinforcing fibers which act as reinforcing elements in the cured board, and retention fibers, which are typically approx. 1/10 as long as the reinforcing fibers and preferably are fibrillated and of hydrophilic character.

Due to the large specific surface area of the retention fibers, a lattice structure is formed which ensures an even distribution of the binder particles. During the extraction of the excess water in the preparation of the green sheets, this grid structure acts as a filter which partly prevents the binder particle from being suctioned together with the aqueous phase and partly from preventing the binder particles from being pulled away from the surface of the reinforcing fibers. Hydrophilic retention fibers also ensure adequate water retention in the green plates.

For example. DE-OS 28 19 794 discloses a process for the production of fiber-reinforced moldings with cellulose fibers as retention fibers and a special type of polypropylene fibers as reinforcing fibers. In this method, it is preferred to disperse the fibers in a portion of the cement binder dispersion, and only thereafter add the remainder of the binder.

However, in the preparation of an initial slurry, both Magnani and Hatschek method may cause problems due to clump formation. In the Hatschek method, additional problems may arise due to the formation of the above clouds in the finished slurry.

In the specification of Danish Patent Application No. 4926/78, these problems are solved by subjecting the slurry to a mechanical shear in a narrow region between two surfaces moving at high speed relative to each other. It is further mentioned that the incorporation of a fine filler such as silica dust consisting of spherical particles with specific surface area of approx.

Λ 25m '/ g in the slurry improves its processability.

20 Since mechanical shear treatment is an energy demanding extra workflow that causes heavy wear, and since the addition of fine silica dust often causes filtration problems by the Magnani method and poor retention by the Hatschek method, it is desirable to find other solutions to the problem of lump formation. .

European Patent Application No. 0 012 546 proposes the addition of ball-clay to a slurry of cement particles, reinforcing and retention fibers as a means of reducing shrinkage of the green sheets during the curing of the cement.

30 Finally, it is from Belgian Patent Specification No. 855729, Example 7, and from the specification to French Patent Application no.

2387920, known to perform a pretreatment of the polymer fibers and retention fibers which are to form part of a dewatered cement matrix together with a paper or cellulose pulp. From Description 35 of Danish Patent Application No. 551/80, it is known to perform this pretreatment of said polymeric and retention fibers with an aqueous slurry of inorganic colloids which precipitate in the slurry. Only then is the cement incorporated into the slurry formed during dewatering, e.g. on a Hat Checking Machine.

However, the basic problem of simply avoiding the formation of fiber clumps in the slurry and providing a slurry with excellent dewatering properties remains to be solved.

From the description to Danish patent application no.

2685/80, which takes priority from February 11, 1980, and became widely available on August 12, 1981, a process for the manufacture of fiber-reinforced cement slabs by the Hatschek method is known. These sheets are reinforced with cotton retention fibers and polyethylene reinforcing fibers and additionally contain clays such as concreteite and / or colloidal silica.

In this process, the cotton and polyethylene fibers are dispersed in water by hydropulping and then the cement and the clay and / or the colloidal silica are added.

It has now surprisingly been found that the above problem can be solved by a modified preparation of the slurry.

The present invention thus relates to a method of producing fiber-reinforced molding articles with a matrix of cured inorganic binder, in which first an aqueous pulp of reinforcing fibers and retention fibers containing a fiber dispersant is produced, after which an aqueous slurry of reinforcing fibers is produced. retention fibers, hydraulic inorganic binder particles and optionally other additives containing more water than necessary to ensure hydration of the inorganic binder by suspending the hydraulic inorganic binder particles and optionally other additives in the aqueous pulp, optionally with further addition of water on which it is prepared. green moldings by dewatering the slurry, after which the green molds are cured, the process being characterized by using at least 0.5% by weight of colloidal refined needles or plate-shaped clay particles with a specific surface area greater than 75m / g and a thickness of approx. 0.012 microns and / or at least 4% by weight of colloidal U9428 7 particles of natural clay having a surface area of at least p 25m / g, which colloidal particles of natural clay are added as an aqueous slurry, the weight percent being expressed as dry matter per minute. total amount of dry matter in the mixture.

5 Speaking as hydraulic, inorganic binders come: Portland cement, alumina cement, cement types containing granulated blast furnace slag such as slag cement,

Portland blast furnace cement and super sulphated cement, puzzolancement containing one of the mentioned cement types 10 and / or lime and natural or artificial puzzolans such as silica, trass, santorine soil, fly ash and the aforementioned silica dust.

Speaking as retention fibers come: Formed celiaculose fibers or synthetic organic fibers, such as polyethylene-15 or high-fibrillation polypropylene fibers, such as Pulpex from Solvay et Cie. SA, Ferlosa from Montedison, Carifil from Shell Chemicals and FPE from Schwarzwalder Textilwerke, preferably cellulose fibers having a fineness of 20-60 ° SR at concentrations of 0.2-8%, preferably 3-8% by the Hatschek-20 method and 0 , 25-4% by the Magnani method, (in both cases weight percent of total dry matter).

Speaking as reinforcing fibers come: Natural and synthetic organic or inorganic fibers at concentrations equal to 0.2-8% (wt.% Of dry matter in the aqueous slurry).

Preferred natural organic reinforcing fibers are cellulose fibers such as kraft cellulose, hemp cellulose, abaca cellulose and cotton cellulose. Preferred synthetic organic reinforcing fibers are polyamide, polyester and polyolefin fibers, especially nylon 6, nylon 11, polyethylene and polypropylene fibers, especially cut, fibrillated polypropylene fibers with a tensile strength of at least 4000 kp / cm and fracture elongation of not more than 8%. , cut into lengths of approx. 12 mm.

Preferred inorganic reinforcing fibers are glass fibers 35 and rock wool fibers.

Preferred reinforcing fibers are cellulose fibers at concentrations of 1-7% and the aforementioned polypropylene fibers at concentrations of 0.2-4% (both by weight of dry matter).

In a preferred embodiment of the process according to the invention, in addition to the above colloidal clay particles, hydrophilic silica particles having a specific supernatant are used.

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5 surface area greater than 100m / g and an average particle diameter of approx. 0.012 microns suspended in the pulp's aqueous phase.

Preferred refined needle or plate clay particles are Attagel, a refined attapulgus clay product from Engelhard A.G.

The colloidal clay particles prepared by suspending natural clay in water are used as aqueous slurries of sedimentary clay types, especially non-kaolinitic clay types, preferably containing a clay dispersant such as sodium hexametaphosphate, sodium pyrophosphate, sodium hydroxide and sodium glass, carbonate, and with a dry matter content of about 40% by weight.

Preferred hydrophilic silica particles are commercially available on available silica sols such as Ludox, from du Pont,

R R

Syton from Monsanto Co., Nalcoag from Nalco Chem. Co., and R · 20 Nyacol from Nyanza Inc., and low bulk silica powders and as finely divided gels such as Cab-0-SilR from Cabot Corp.,

R R

Syloid from Davison Div., Grace Co., Santocel from Mon.

R R

santo Co., Vaylar from PPG Industries, Aerosil from

TEN

Degussa Inc., and Quso of Philadelphia Quartz Co.

When hydrophilic silica particles are used, these are added in amounts of 0.5 to 8% by weight, and the refined needle or plate-shaped clay particles are preferably added in amounts of 0.5 to 2.5% by weight and (or) the colloidal clay particles having a surface area Atleast

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30 m / g in the form of an aqueous slurry formed by suspension preferably in amounts of 4 to 20% by weight, in all cases calculated as the amount of dry matter relative to the total amount of dry matter.

The colloidal clay particles used in the invention are believed to act as inorganic dispersants for the fibers. It has been found that in the two-stage preparation of the slurry, with the suspension of the colloidal clay particles, hereinafter also referred to as "the colloidal dispersant", in the aqueous phase of the fiber pulp (i.e. preparation and use of an aqueous colloidal solution as a water phase in the fiber pulp) the first step is essential for obtaining a satisfactory fiber distribution in the slurry prepared in the next step.

The order of mixing of the components, i.e. water, retention and reinforcement fibers, and colloidal clay particles, in the pulp produced in the first stage of the preparation of the aqueous slurry, are not critical.

In contrast, efficient distribution of the colloidal particles in the aqueous phase and thorough mixing of the fibers and aqueous colloidal solution are important.

In a preferred embodiment of the invention, the aqueous pulp is made of reinforcement and retention fibers containing colloidal clay particles suspended in the aqueous phase as follows: A pulp of retention and reinforcement fibers is prepared in water, then the colloidal clay particles are added to the pulp, then suspended. those in the aqueous phase by stirring the pulp, and finally, additional reinforcing fibers are optionally incorporated into the pulp. The colloidal refined clay particles can be added and suspended in the aqueous phase as a dry powder or as an aqueous suspension. The natural colloidal clay particles are added as an aqueous slurry.

In some cases, it may be desirable to improve the drainage properties of the finished slurry.

This can be achieved by using elongated inorganic particles having a length / diameter ratio greater than 3, preferably greater than 10, and a diameter less than 0.1 mm, preferably stone wool fibers or needle-shaped crystals of

Wollastonite as an additive in the preparation of the aqueous slurry.

Hereby, significantly improved filtration properties are obtained without the strength loss associated with the addition of flocculants.

In addition, in the case of additives added in the preparation of the aqueous slurry, e.g. known fillers, dyes, bonding and curing regulators and waterproofing agents.

149428 ίο When the green moldings are produced by the Magnani method, the aqueous slurry whose water / dry matter ratio is approx. 1, is used immediately in the Magnani machine. Due to a greatly improved fiber distribution, improved retention properties of the retention fibers are noted. Furthermore, the excellent properties of the slurry in distributing, supporting and supporting the fibers, in particular the reinforcing fibers, are expressed by fine surface character and good strength properties of the finished product.

10 Using the Hatschek method, the dilute starting slurry is diluted, whose water / dry matter ratio is approx. 2, ca.

5-10 times with water. Due to the improved distribution of the fibers, in particular of the reinforcing fibers, the improved homogeneity of the slurry is shown by good operating characteristics during the pick-up process on the sieve cylinder, during the dewatering process and during winding on the format roll, resulting in an excellent finished product. .

In the following, the invention is further illustrated by a number of examples.

The following materials are used in the Examples:

Hydraulic inorganic binders.

Portland cement: Type I, specific surface

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(Blaine) approx. 3300 cm / g.

25 L.A. Cement: Portland cement with low alkali content, specific surface Λ (Blaine) approx. 3000 cm / g · E. cement: A special coarse Portland cement, specific surface (Blaine) approx.

2600 cm 2 / g.

Puzzolan additives.

Silica dust: Fine filter dust from electrothermal production of Si, SiOj *

Content: 80-95%, specific surface area: approx. 25 cm / g, mean particle diameter: approx. 0.1 micron.

Fly ash: Fly ash from power plant, specific surface: approx. 3500 cm / g · 149428 il

Filler.

ASP 400: Aqueous aluminum silicate, flat sheets, medium particle size approx. 5 microns.

5 Retention fibers.

BO cellulose: Bleached cellulose fibers (Betula) with a grinding degree of approx.

20 ° sRf length: approx. 1.3 mm, diameter: approx. 30 microns.

10 EO cellulose: Bleached cellulose fibers (Myrtaceae) with a grinding degree of approx. 20 ° SR, length: approx. 1.0 mm, diameter: approx. 20 microns.

Reinforcement fibers.

15 AO cellulose: Cellulose fibers (Pinus) (Kraft cellulose), length: shorter than 4 ram, diameter: approx. 35 microns.

These fibers contain a fine fraction which acts as retention fibers.

Abaca: Cellulose fibers (Musa), length: approx. 6 mm, diameter: approx. 30 microns.

Cotton: Cut Cellulose Fiber 25 (Gossypium), Length: approx. 10 mm, diameter: approx. 10-20 microns. These fibers contain a fine fraction that acts as retention fibers.

CEMFILE: Bundles of alkaline resistant glass fibers from Fiberglass Ltd., length approx. 12 mm, filament diameter approx.

10 microns.

Polypropylene: Fibers made as described in Example 10.

149420 12

Colloidal dispersants.

p

Attagel Λ 150: Commercially available colloidal, needle-shaped attapulgus 5 clay product, with specific surface area: 210 m2 / g.

Lerslam Rørdal and Denmark: Colloidal aqueous slurries made from unrefined cementitious moraine types, 10 specific surface: 25 m / g, dry matter content: 40% by weight.

Aerosil R 200: Commercially available alkali stabilized colloidal silica, specific surface area 200 15 m2 / g average particle diameter: 0.012 micron.

Ludox R HS40: Alkali stabilized silica sol, silica content: 40%, specific surface area: 220-235 m2 / g »20 average particle diameter 0.014 micron.

Filtering Helped media.

NYAD R g: Needle-shaped crystals of

Wollastonite, length: approx. 22 25 microns, length / diarrhea ratio: 5-15.

Stone wool fibers: Commercially available stone wool fibers (from Conrock), length: approx. 0.75 mm, diameter: 5 microns.

30

Fiber-reinforced plates were made by laboratory experiments, on a full industrial scale Magnani machine, and on a full industrial scale Hatschek machine.

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Laboratory tests:

Preparation Procedure A.

Pulp Preparation: A solution of 3.4 g Ca (OH) 2 and 5.1 g Ca SO 4, 2H 2 O in 1700 ml deionized 5 water was prepared. The solution was introduced into a British Pulp Evaluation Apparatus. Ca. 80 g of retention and reinforcement fibers, except polypropylene fibers, were added to the solution and the mixture was pulped for 15 minutes at 3000 rpm. Then any ca. 4 g of polypropylene fibers, and the resulting mixture 10 was pulped for 2.5 minutes.

Preparation of slurry: The resulting fiber pulp was transferred to a vessel and a slurry was prepared by adding hydraulic inorganic binder and optionally puzzolan and other additives to the stirred pulp (285 rpm) in an amount corresponding to a total of 1700 g of dry matter. The slurry was stirred for 3 min.

Preparation of Green Plates: A portion of the slurry, corresponding to 140 g of dry matter, was pressed into green plates in a Johns-Manville plate press at 15 kp / cm 2 for 60 sec.

Preparation of Cured Plates: The green plates were cured to cured plates as follows: The green plates were placed on a glass plate and stored in a humidity box for 24 hours, relative humidity: approx. 95%, temperature 25 ° C. The plates were then immersed in water for 6 x 24 hours, temperature: 25 ° C.

This method was used in the preparation of a slurry having a weight ratio of water / total dry matter amount of approx. 1, which corresponded to the ratio of the Magnani method. The properties of a Hatschek slurry with a similar ratio equal to approx. 10, was examined using the following procedure:

Manufacturing Procedure B ♦

Pulp making: A pulp containing approx. 20 g of fiber in 2000 ml of the above solution was prepared as described in Preparation Procedure A.

Preparation of slurry: The fiber pulp was transferred to the vessel in a Diaf Mixer and an additional amount of the above solution was added up to a total volume of water, corresponding to 5000 ml. The resulting mixture was stirred at 4000 rpm and a slurry was prepared by adding hydraulic binder and optionally puzzolanic and other additives to the stirred pulp in an amount equal to 500 g total dry matter. The slurry was stirred for 6 min.

Preparation of Green Plated Portions of 1300 ml of slurry were dewatered in a filtration apparatus, suction pressure 200 mm hg.

The resulting filter cakes were pressed into green plates in one

A

Johns-Manville plate press at 15 kp / cmz for 60 sec.

Preparation of Cured Sheet: As described in Preparation Procedure A.

A number of products according to the invention (test type O) and a number for comparison (test type S) were prepared.

When products of the invention were prepared, the addition of the colloidal dispersant in the pulp-making phase occurred before the addition of polypropylene fibers, and the pulp was stirred for 2.5 minutes. after the addition of colloidal dispersant.

The physical properties of the slurry and cured boards 20 were measured and determined as described below:

Testing Procedure:

Filtration time: Slurry prepared according to Preparation Procedure A. An amount of slurry corresponding to 180 g of dry matter was dewatered in a filtration apparatus at a suction pressure 25 corresponding to 200 mm Hg. A sudden decrease in suction pressure indicates the end of the filtration period. The filtration time is defined as the elapsed time from the start of the suction until the pressure drops.

Slurry prepared according to preparation procedure 30 Bj_ Same procedure as above, but using 1300 ml of slurry.

Dry matter loss: The particle retention properties of the slurry prepared in accordance with Preparation Procedure B were measured as follows: 3 slurry portions of 440g 35 were dewatered in a filtration apparatus equipped with a 40 mesh screen, suction pressure: 30mm Hg. The solids content of the filtrate was filtered off and the weight of the filtered material was determined. Loss of solids is defined as the ratio of the solids content of the filtrate to the total solids content, expressed as a percentage by weight.

The nature of the slurry: The tendency of the fibers to clump together in the slurry prepared according to Preparation Procedure A was determined manually by rubbing the slurry between the fingers. The properties of the slurry got the following marks: "1": Slurry slurry without lumps. "2": Small clumps present. "3": Large chunks present.

10 BT-max dry and wet, 7 days: The cured plates were subjected to bending test tests, during which the curvature of the samples was determined as a function of the load. A ZWICK 1474 4-point loading machine with 190 mm between the 15 supports and a 35 mm torque arm was used. Force / deformation curves were recorded. BT-max indicates the maximum tensile stress when bending at maximum load. Subsequent "wet" indicates that the plates were taken directly from the curing phase and "dry" that the fresh cured plates were dried for 48 hours at 110 ° C before being subjected to bending test.

Example 1.

Comparison between sheets made according to the invention and sheets made according to the prior art. (Preparation Procedure A).

Five test series were conducted with the manufacture of plates according to manufacturing procedure A.

In experiments 1 and 3, the plates were prepared without the addition of any colloidal dispersant.

In experiments 2 and 4-5, colloidal dispersants were added to the fiber pulp of the invention described above.

Compositions and test results are shown in Table I.

It will be apparent that the sheets made according to the invention exhibit better properties than the sheets made for comparison.

The plate preparation in Experiment 3 was extremely difficult, as the fibers were extremely prone to clumping. Therefore it was necessary to work at a fairly high v / t ratio. These problems did not appear at all in Experiments 4 and 5.

5

Example 2.

Plate making according to the invention.

A plate is prepared according to Preparation Procedure A including addition of NYAD G to the slurry.

10 Composition and test result are shown in Table II.

Example 3

Effect of adding colloidal dispersant to the fiber pulp compared to adding the same material to the slurry.

Four test series of plate preparation were performed according to Preparation Procedure A.

In two rows (Exercises 7 and 9), the colloidal dispersant 20 was added to the fiber pulp as an aqueous slurry, i.e. according to the invention. In the other two rows (Examples 8 and 10), the colloidal dispersant was not added according to the invention, i.e. not to the fiber pulp, but to the slurry.

25 Compositions and test results are shown in Table III.

Evidently, the order of mixing of the components is essential for the provision of good product properties.

30

Example 4

Plate making according to the invention.

Twelve plates of plate preparation were conducted according to Preparation Procedure A with various combinations of colloidal dispersant added to the fiber pulp. Experiments 23-26 show the effect of not including any colloidal dispersant.

Compositions and experimental results are shown in Table IV.

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It will be apparent that the sheets made according to the invention are of superior quality.

Example 5

Plate manufacture according to the invention.

Two test rows were carried out with plate preparation according to production procedure A. In both rows 20% by weight (on a dry basis) mud sludge Rørdal was added to the fiber pulp according to the invention, but in experiment 28 the sludge was added 0.025. 10% by weight of a highly cationic polyacrylamide polyelectrolyte "XI" from Ploerger S.A. as flocculant.

Compositions and test results are shown in Table V.

Example 6.

Effect of the addition of fine silica dust.

It is known in the art to add fine silica dust, i.e. silica dust as defined above.

The basic difference between silica dust and the colloidal 20 hydrophilic inorganic particles of the invention was illustrated by the following plate preparation experiments according to Procedure A.

In the first experiment, experiment 29, the fiber pulp 2% by weight of silica dust, in the second experiment, 30, 25 the fiber pulp 2% by weight Attagel 150, in the third experiment, 31, between the fiber pulp 2% by weight Attagel 150 and the slurry 2% by weight of silica dust was added and in the fourth experiment, No. 32, neither silica dust nor Attagel 150 were added to pulp or slurry.

30 Compositions and test results are shown in Table VI.

The results show that adding silica dust to the pulp does not prevent lump formation in the slurry, as Attagel 150 does. Comparison between experiments 29 and 32 35 shows a slight increase in BT-max, dry by the addition of silica dust, which can be explained by the excellent pozzolanic activity of the silica dust.

149428 18

It is obvious that the products made according to the invention are of superior quality in terms of strength properties. Also, the products made in accordance with the invention have better surface character because the sheets made in experiments 30 and 31 have a smooth surface, while the sheets made in experiments 29 and 32 have fibers protruding through the surface.

The plates made in Experiment 30 are preferred over the plates made in Experiment 31 because adding a small amount of silica dust, even less than 1% by weight, causes an undesirable dark staining of the plates.

Example 7

Comparison between sheets made according to the invention and 15 sheets made according to the prior art. (Preparation Procedure B).

Twelve series of plate preparation experiments were performed according to Preparation Procedure B.

The BO cellulose fibers had a grinding degree of approx.

20 58 ° SR after pulping.

In three experiments (experiments 33, 39 and 43), plates were prepared without the addition of any colloidal dispersant.

In other experiments, the fiber pulp colloidal dispersant was added as described above. Experiments 38 and 42 illustrate the effect of adding NYAD G and rock wool fibers to the slurry.

Compositions and experimental results are shown in Table VII.

The results show that a significant increase in the strength of the plates is obtained by the addition of colloidal dispersant to the fiber pulp.

The preferred filtration time is less than 300 seconds and a dry loss of approx. 10% is acceptable in the manufacturing process mentioned.

35 Experiments 41-42 demonstrate the effectiveness of NYAD G as a filtration enhancing aid.

19 149428

Example 8 »

Attempts at a full-scale Magnani machine.

146 kg AO cellulose and 122 kg BO cellulose were pulped 3 with 6500 l water x 40 mxn. x and 13 m Black Clawson pulps.

Then, 24 kg of polypropylene fibers were added and the pulp was pulped for 5 minutes. Then 122 kg of Attagel 150 was added and the mixture was pulped for 10 minutes. Finally, a quantity of clay sludge Rørdal corresponding to 974 kg of dry material was added and the pulp. pulped for 5 min.

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The pulp was transferred to a 4 no FL Smxdth agitator, 10 and Portland cement, NYAD G and Wollastonite FW200 (Wollastonite particles with a mean length of about 20 microns, length / diameter ratio of about 3 from Pargas Kalk AB) were added in quantities corresponding to 80 kg of Portland cement, 10.2 kg of NYAD G and 6.8 kg of Wollastonite FW200 per kg. 107 kg pulp. The resulting slurry was stirred for 15 min. Then the slurry was pumped into a Magnani machine where it was dewatered to corrugated sheets.

The plates were set up and passed through a curing channel where they were cured by the heat generated by the hydration of the cement. The residence time in the curing duct was approx. 7 hours.

After approx. For 4 hours, a temperature of 100 ° C was reached. The cured plates were removed from the molds and stored at 25 ° C for 7 days.

Testing.

The BT-max of the plates was measured almost as described above, but with a 3-point load.

BT-max 1 (with rupture parallel to the waves) 8.1 MPa.

BT-max t (with rupture perpendicular to the waves) 9.3 MPa.

Room weight: 1.45 g / cm.

Example 9.

Attempt on a full scale Hatschek machine.

Experiment Hl.

86 kg of abaca cellulose were pulped for 30 min. with 2500 1

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water x a 3 m Solvo pulper. 138 kg BO cellulose was pulped in

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35 10 min. with 4000 l of water in a 7 nr solvo pulper. The resulting BO cellulose pulp had a fineness of 50 ° SR. The two 3 pulses were transferred, for example, to a 7 m Solvo pulper and 68 kg of Attagel 149428 20 150 into the pulse. Mixing time: 5 min. Then a quantity of clay sludge Rørdal corresponding to 512 kg of dry matter, 171 kg of rock wool fibers and 17 kg of polypropylene fibers was added and the mixture was mixed for 10 minutes.

5 3383 kg of the resulting pulp was mixed with 994 kg of E. cement to an output Hatschek slurry with a v / t pre-ball, i.e. water in premix for total dry matter amount, corresponding to approx. 2.1.

The initial training was diluted with water to give 10 v / t ratio corresponding to approx. 10, and processed into flat sheets in a known manner in a Hatscbek machine. The plates Λ were pressed at 125 kp / cm for 20 minutes, and the pressed plates were cured and stored for 28 days, as described in Example 8. Testing.

15 Two values were measured for the T-max of the plates, which described one in connection with the laboratory experiments.

BT-max 1 (with breakage parallel to the direction of the filter cloth).

BT-max t (with breakage perpendicular to the direction of the filter cloth).

Composition and test results are presented in Table VIII.

Experiment H2-H5.

Four other plate types were prepared as described above.

25 Compositions and test results are shown in Table VIII.

Example 10.

Preparation of the polypropylene fibers used in Examples 1-9.

The fibers were prepared as follows:

ICI GWE 23 polypropylene with a melt index of 3 g / 10 min was used. measured according to DIN MFI 230 / 2.16.

The polypropylene was extruded into a blown tubular film in a standard extrusion / stretching plant at an extrusion temperature of 180-220 ° C and the tubular film was cooled with cooling air at 18-20 ° C and cut into two film strips.

From an extruder station after the extruder, the film was passed through a hot air oven with an air temperature of 180 ° C and an air velocity of 25 m / sec. Using greater rolling speed in the stretching station after the hot air oven, the film was stretched in a ratio of 1:17. Then, the film was heat-stabilized by passing through a hot air oven with an air temperature of 5 180 ° C and an air velocity of 25 m / sec. 90 m / sec

The film thickness was 20 microns.

The film was fibrillated to fiber filaments of from 2 to 30 dtex using a ReifenhSuser FI-S-0800-03-01 fibrilator with 13 needles per cm. in each of two consecutive staggered needle rows spaced at the same distance as the interval between two needles. The fibrillation ratio (= ratio of the film advancement rate to the peripheral velocity of the fibrillator roller) was 1: 3. Then, 1 wt% hydrophilic 15 avivage (Henkel LW 421) was applied as a 1: 9 aqueous slurry and the fibers were cut to lengths of 12 mm in a stack cutter.

Experiment No. 1 2 j 3 4 5 22

TABLE I

149428

Portland cement L.A. cement E. cement_97.75 95.75 94.5 74.5 90.75

silica dust

Fly ash ______ BO cellulose EO cellulose______ AO cellulose 2.0 2.0 5.0 5.0 5.0

abaca

Cotton

Polypropylene_0.25 0.25 0.25 0.25 0.25

Attagel 150 2.0 4.0

Aerosil 200 Ludox HS 40 Lerslam Rørdal

Lerslam Denmark 20

NEW G

STONE WOOL FIBER______ TEST TYPE S 0 S O 0 V / t in slurry (x) __ 1.0__1.0__1.3__1.05 1.3_

Filtration time (sec) L7__31__9__57__28_

Room weight (g / cm3) __ 1.65 1.72 1.42 1.63 1.52 BT-max wet, 7 days, MPa 7.3 9.4 6.6 13.2 10.7 BT-max dry, 7 days, MPa (y) (y) __ 8.8 15.1 11.3

Op paralysis rate__3__1__3__1__1_ (x) weight ratio water / total dry matter amount (y) not measured

Experiment No. 6 23 149428

TABLE II

Portland cement L. A. cement E. cement__83,75_

silica dust

Fly ash__ BO cellulose EO cellulose___ AO cellulose 2.0

abaca

Cotton

Polypropylen__0,25_

Attagel 150 2.0

Aerosil 200

Ludox HS 40

Lerslam Rørdal

Lerslam Denmark NEW G 12.0

Stenuldsfibre__

TEST TYPE O

y / t in slurry (x) __ 1.0_

Filtration time (sec) __ 15_

Room weight (g / cm3) __ 1.65_ BT-max wet, 7 days, MPa 10.6 BT-max dry, 7 days, MPa__

Slurry character__1 (x) weight ratio water / total solids content

TABLE III

Experiment No. 7 8 9 10 24 149428

Portland cement L.A. cement E. cement__87.25 87.25 73.75 73.75

silica dust

Fly ash _____ BO cellulose 1.5 1.5 EO cellulose_____ AO cellulose 2.0 2.0 2.0 2.0

abaca

Cotton

Polypropylene 0.25 0.25 0.25 0.25

Attagel 150 2.0 2.0

Aerosil 200 Ludox HS 40

Lerslam Rørdal 7.0 7.0

Lerslam Denmark 12 12 NEW G 12 12

Stenuldsfibre_____

TEST TYPE 0 S 0 S

V / t in slurry (x) __ 1.0 1.0 0.85 0.85

Filtration time (sec) __ 48__29__49__20_

Volume weight (g / cm3) __ 1.58 1.48 1.66 1.53 BT-max wet, 7 days, MPa 10.4 6.6 12.4 6.2 3T-max dry, 7 days, MPa____

Slurry character_1__3__1__3_ (x) weight ratio water / total dry matter amount 149428

TABLE IV

Experiment No. 11 12 | 13J14] 15 16 (weight percent, dry matter basis)

Portland cement L.A. cement 70.25 85.5 84.5 E. cement__77.5 89.75 83.5 ____

silica dust

Fly ash ______ BO cellulose 1.50 1.50 EO cellulose ______ 1.5 1.5 AO cellulose 2.0 1.5 1.5

abaca

Cotton 6.0

Polypropylene 0.25 0.25 0.25 0.25 3.0 4.0

Attagel 150 1.25 1.25 3.5

Aerosil 200 Ludox HS 40

Lerslam Rørdal 20.0 10.0 10.0

Lerslam Denmark 8.0 6.0 6.0 NEW G 12.0 6.0

Stenuldsfibre_______

TEST TYPE 0 0 O O O O

P / t in slurry (x) __ 0.88 1.0__1.0 1.5__0.9 0.9

Filtration time (sec) __ 18__68__32__86__88__68_

Room weight (g / cm3) __ 1.64 1.66 1.69 1.49 1.54 1.48 BT-max wet, 7 days, MPa 13.2 9.6 11.7 10.5 10.6 10, 7 BT-max dry, 7 days, MPa__14.8 __ (j £) __ 15.4 16.5__13.6 15.1

Dp slurry character_ 1 j 1__1 1__1 1 (x) weight ratio water / total dry matter amount (y) not measured

Experiment No. 17 18 18 20 21 22 TABLE IV (continued) 26 149428

Portland cement 82.5 L.A. cement 84.25 72.25 84.5 77.5 E. cement ______ 77.75 _

Silica dust 12.0 5.0 5.0

Fly ash ______ BO cellulose EO cellulose__1.0 1.5 2.5 1.5 ___ 1.5 AO cellulose 1.0 1.0 3.0

abaca

Cotton 1.0

Cemfil 5.0

Polypropylene__0.25 3.0__3.0__3.0__0.25

Attagel 150 1.25 1.25 1.25 2.0 1.0

Aerosil 200 Ludox HS 40

Lerslam Rørdal 7.0 10.0 10.0 10.0 5.0 10.0

Lerslam Denmark NEW G 6.0 12.0

STONE WOOL FIBER_______ TEST TYPE O O 0 0 0 0 V / t in slurry (x) · __1,0__1,0__1,0__0.9__1.0__0.8

Filtration time (sec) __ 33__70__285__60__15__110_

Volume weight (g / cm3) ____ 1.65 1.62__1.63 1.49__1.56 1.77 BT-max wet, 7 days, MPa 12.3 13.2 15.4 10.2 11.4 16.7 BT -max dry, 7 days, MPa ___ 13.3 17.2 17.5 12.6 11.6 17.8

Op paralysis character__1 1_1 1 | 1 In 1_ (x) weight ratio water / total dry matter quantity TABLE · IV (continued) 27

Experiment No. 23 24 25 26 149428

Portland cement L.A. cement E. cement__74.75 94.75 94.75 97.0__

Silica dust ASP 400 10.0

Fly ash ______ BO cellulose 4.5 1.25 EO cellulose__1.5__4.5 ____ AO cellulose 1.5 0.5 0.5 1.5

abaca

Cotton

Polypropylen__0,25__0,25__0,25__0,25__

Attagel 150 Aerosil 200 Ludox HS 40 Lerslam Rørdal Lerslam Denmark NEW G 12.0

Stenuldsfibre______

TEST TYPE S S S S

V / t in slurry (x) __ 0.9__1.2__1.2 1.0 ___

Filtration time (sec) __ 8__6__5 7___

Room weight (g / cm3) __ 1.52__1.45 x1.45__1.58 ___ BT-max wet, 7 days, MPa 7.2 5.8 4.9 5.4 BT-max dry, 7 days, MPa____8, 5__8.4__7, 1__7,6__

Op's paralysis rating__3_ 3__3 3___ (x) weight ratio water / total solids content

TABLE V

28

Experiment No. 27 28 149428

Portland cement L.A. cement E. cement__74,75__74,75__

silica dust

Fly ash _; ____, BO cellulose EO cellulose____ AO cellulose 5.0 5.0

abaca

Cotton

Polypropylen__0,25__0,25 ___

Attagel 150 Aerosil 200 Ludox HS 40

Lerslam Rørdal 20.0 20.0

Lerslam Denmark NEW G

Cationic polyelectrolyte "X 1" __-__ 0.025 _____ FORMS ^ G TYPE O 0 V / t in slurry (x) __ 1,2__1,2__

Filtration time (sec) __ 49__28___

Room weight (g / cm3) __ 1.63 _1.57__ BT-max wet, 7 days, MPa 10.2 7.6 BT-max dry, 7 days, MPa_____

Slurry character__1__2__ (x) weight ratio water / total dry matter amount

Experiment No. 29 30 31 32 29 149428

TABLE VI

Portland cement L.A. cement E. cement __._ 94.25 94.25 92.25 96.25__

Silica dust 2.0 2.0

Fly ash BO BO cellulose 1.5 1.5 1.5 1.5 EO cellulose ______ AO cellulose 2.0 2.0 2.0 2.0

abaca

Cotton

Cemfil

Polypropylene _____ 0.25 0.25 0.25 0.25__

Attagel 150 2.0 2.0

Aerosil 200

Ludox HS 40

Lerslam Rørdal

Lerslam Denmark

NY AD G

Stenuldsfilbre______

TEST TYPE S O O S

V / t in slurry (x) __ 1.0 1.0__1.0 1.0 ___

Filtration time (sec) __ 17__25__23__9__

Room weight (g / cm3) __ 1.52 1.64 1.63 1.46 __- BT-max wet, 7 days, MPa 7.2 9.0 9.0 6.9 BT-max dry, 7 days, MPa_____ __

Slurry character_ 3__1__1 3__ (x) weight ratio water / total dry matter amount 149426

TABLE VII

30

Experiment No. 33 34 35 36 37 38

Portland cement L.A. cement E. cement_ 94.5 92.5 78.5 79.5 78.0 71.0

silica dust

Fly ash _______ <_ BO cellulose 4.5 4.5 4.5 4.5 4.0 4.0 EO cellulose______ AO cellulose 0.5 0.5 0.5 0.5

Abaca 2.5 2.5

Cotton

Polypropylene 00.5 0.5__0.5__0.5 0.5 0.5

Attagel 150 2.0 2.0

Aerosil 200

Ludox HS 40 1.0

Lerslam Rørdal 15.0 15.0 15.0 15.0

Lerslam Denmark NEW G

Stonewoods ______ 5.0 5.0_

TEST TYPE S O O OOO

V / t in slurry (x) __ 10__10__10__10__10__10_

Filtration time (sec) __ 48__64__441__331 146___145_ Solids loss (%) (xx) __ 6.5__7.6__6.8__7.0 6.9__4.8_

Room weight (g / cm3) __ 1.42 1.44 1.57__1.55 1.48 1.36 BT-max wet, 7 days, MPa 5.4 7.0 11.5__10.7 11.2__9.5 (x ) weight ratio water / total solids content (xx) by weight 31

Experiment No. 39 40 41 42 43 44 TABLE VII (continued) 149428

Portland cement L.A. cement E. cement__96.0 94__86__76__84.5 69.5

silica dust

Fly ash ______10__10 BO cellulose 3.0 3.0 3.0 3.0 4.5 4.5 EO cellulose______ AO cellulose 0.5 0.5 0.5 0.5 0.5 0.5

abaca

Cotton

Polypropylen__0,5__0,5__0,5__0,5__0,5__0,5

Attagel 150 222

Aerosil 200 Ludox HS 40

Lerslam Rørdal 8 8

Lerslam Denmark 15 NEW G 10 S tenulds f ilbre________

TEST TYPE SO 0 O SO

V / t in slurry (x) __ 10__10__10__10__10__10

Filtration time (sec) __ 60__93__353__189__48 371 Solids loss (%) (xx) __ 9.1 10.4 11.2 8.3 5.3 8.7

Volume weight (g / cm3) __ 1.48 1.52 1.60 1.50 1.34 1.52 BT-max wet, 7 days, MPa__5.5 7.4__8, 7__8.0__3.8 9.5 (x) weight ratio water / total dry matter amount (xx) by weight 32

TABLE VIII

149423

Experiment No. H1 H2 H3 H4 H5 (% by weight, dry matter basis)

Portland cement L.A. cement E. cement_ 71_86_76_79.5_69.5_

silica dust

Fly ash _____ BO cellulose SR50 4 4 4 4.5 4.5 EQ cellulose ________________ AO cellulose 0.5 0.5

Abaca 2.5 2.5 2.5

Cotton

Polypropylen_0,5_0,5_0,5_0, J5_0,5_

To tag 150 2 2 2

Aerosil 200 Ludox HS 40

Lerslam Rørdal 15 15 15 15

Lerslam Denmark NEW G 10

Stonewool fibers_5_5_ TEST TYPE 000 00

Room weight, g / cm3_1.63_1.63_1.46_1.49 1.70_ BT-max 1, 28 days, MPa 19.2 14.2 11.0 12.6 15.1 BT-max t, 28 days, MPa 26 , 2 18.8 17.1 19.0 18.2

Claims (3)

149428 PATENT REQUIREMENT. A process for preparing fiber-reinforced molding articles with a matrix of cured inorganic binder, first producing an aqueous pulp of reinforcing fibers and retention fibers containing a fiber dispersant, then producing an aqueous slurry of reinforcing fibers, retention fibers, binder particles and optionally other additives, 10 containing more water than necessary to ensure hydration of the inorganic binder by suspending the hydraulic inorganic binder particles and optionally other additives in the aqueous pulp, optionally with further addition of water producing green mold gene -15 stands for dewatering the slurry, after which the green moldings are cured, characterized in that at least 0.5% by weight of colloidal refined needle or plate-shaped clay particles having A a specific surface area greater than 75m / go is used g a thick! 20 look at approx. 0.012 microns and / or at least 4% by weight of colloidal particles of natural clay having a surface area of at least A 25m / g, which colloidal particles of natural clay are added as an aqueous slurry, the percentage by weight being expressed as dry matter per minute. total amount of dry matter in the mixture. Process according to claim 1, characterized in that, as a fiber dispersant, in addition to 0.5-2.5% by weight of the needle or plate-shaped clay particles and / or 4-20% by weight of the colloidal clay particles having a surface area of at least 25m2 / g further 0.5-8 30% by weight of colloidal hydrophilic silica particles having a specific surface area greater than 100m / g and an average particle diameter of approx. 0.012 microns suspended in the pulp's aqueous phase. Process according to claims 1-2, characterized in that cellulose, polyamide, polyester and polypropylene fibers are added as a reinforcing fiber in an amount corresponding to 0.2-8% by weight of dry matter in the aqueous slurry.