FI76544B - ARK SAMT FOERFARANDE FOER DESS FRAMSTAELLNING. - Google Patents

Description

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9SjTJ ci (patemtskrift 7654 4 (51) Kv.lkJlnt-CI ^ C Qi) B 16/06 (21) Patent application - Patenunsöknlng 773955 v -7 (22) Hakemitptivl - Ansökningsdag 28.12.77 (23) AlkupSivl - Gfltighetsdag 28.12.7 FINLAND —FINLAND (41) Has become public - Blivit offentlig 29.06.79 xpax (44) Date of publication— 29.07.88 \ · / Antäkan utlagd och utl.skriften publicerad (45) Patent granted - Patent meddelat 10.11 .88

National Board of Patents and Registration (86) International application - Int.ansökan

Patent- och registerstyrelsen (32) (33) (31) Claim claimed - Begird prloritet (73) Netcem International Holdings S.A., 15 Boulevard Roosvelt, Luxembourg,

Luxembourg (LU) (72) David James Hannant, Great Bookham, Surrey, United Kingdom-Storbritannien (GB) (74) Oy Hei nänen Ab (54) Record and method of production - Ark samt förfarande för dess f ramstäi In ing

The present invention relates to a sheet or other product comprising a network structure of organic matter connected to a water-cured mass.

It has been known for many years that asbestos and especially the so-called blue asbestos poses a health risk both to workers working in mineral mines and to users, especially when the user has to handle material containing asbestos fibers by cutting or sawing objects from it.

The construction industry has produced asbestos-cement boards and other products, such as pipes and gutters, which 2 76544 are commonly used in low-load areas due to their low cost and weather resistance properties. When installed, the asbestos content of such products no longer adversely affects the occupants of the building, but it has been found that up to the installation stage, those who come into contact with asbestos-containing products are exposed to significant health hazards, Numerous alternatives to asbestos-cement products , which include all traditional building materials, but all have the disadvantage that they are substantially more expensive or involve higher labor costs during the installation phase or, in some cases, during transport.

As a result of these factors, many attempts have been made to replace products based on asbestos-cement mixtures, but the disadvantages of the results so far have been that the products have been too expensive compared to asbestos-cement products and / or have poorer properties.

British Patent 1,130,612 proposes the addition to water-curable pulp of a mixture consisting entirely or mainly of one or more inorganic substances and water which can be curable to a solid, cohesive pulp, up to 2% by weight of short fibers formed stretched and subsequently defibered film. This patent further suggests that the film should be a polyolefin film, and in particular a polypropylene film, the fibers disclosed in the publication having a maximum length of 7.5 cm, and thin sheets made of a mixture containing such fibers would be unsuitable for most applications.

British Patent 1,429,167 also proposes the use of a fiber-reinforced alloy having a physically uniform, preformed compound comprising absorbent fibers and reinforcing fibers of glass, steel, carbon, boron, copper, bronze, aluminum mixture, asbestos or silicone compound, non-absorbent polyamide, non-absorbent polyester, non-absorbent polyacrylate, polyolefin or polyurethane. In addition, it has been suggested in this publication that the pre-combination may comprise a pre-woven ribbon, fabric or mesh.

4

In the examples in said patent publication, only steel wires and glass fibers have been used as reinforcing fibers. Using these in combination with absorbent fibers provides satisfactory strength properties. However, the premixing requirements for reinforcing fibers and absorbent fibers necessitate an additional process step, resulting in an expensive product. The fact that asbestos is mentioned as a possible reinforcing fiber proves that the purpose of the proposal was not to replace asbestos cement tiles but instead to improve the strength properties of such tiles,

British Patent Specification 1,404,755 discloses a cementitious product reinforced with a fabric or mat of synthetic or organic polymeric material. According to the publication, these are spaced apart at different points in the concrete structure. However, this product has not been able to replace asbestos cement products and has not been used in practice, U.S. Pat. No. 3,591,395 discloses a water-curable mass reinforced with organic material. The publication contains a reference to a woven mesh, but nevertheless states in the claims and examples that the fibrillated polypropylene cut into short pieces is used as a reinforcement. This publication has not brought about a practical solution to the problem of replacing asbestos cement products either.

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It is an object of the present invention to provide a board or similar product which provides a useful alternative to asbestos cement products which is competitive with asbestos cement products. The invention is characterized in that the mesh structure contained in the product is formed of a fibrillated organic film and that the mesh structure is connected to the water-cured mass in several continuous overlapping layers.

By using a continuous organic fibrillated film incorporated as a mesh structure in the water-curable mass, it becomes possible to produce articles with at least certain proportions substantially better properties than, for example, asbestos-cement products, in addition to which they are cost-competitive.

The mesh structure used in the product is preferably based on a fibrillated polyolefin film, as it provides very good properties at a cost that is currently competitive with ordinary asbestos fibers. By using the most preferred reinforcing material, namely polypropylene, by incorporating a large number of layers per centimeter of product thickness, a final product with sufficiently good strength properties for the production of cement-based sheets can be obtained, whereby the product is not only competitively priced with asbestos products but also has properties that allow it to be used for many different purposes and conditions where asbestos cement products cannot be used.

For certain purposes, it may be advantageous to place at least one intermediate layer, 5 76544, of water-cured mass or other material with no reinforcement at all between the two layers of water-cured mass and the mesh structure.

The present invention also relates to a method for manufacturing the above-mentioned sheet or the like. In the method, a network structure of organic matter is formed and this network structure is combined with a water-curable mass, after which the mass is cured. Particularly characteristic of the method is that the network structure is formed of a fibrillated organic film and combined with the water-curable mass in several continuous overlapping layers.

The expression "water-curable mass" in this context means a dry or substantially dry mixture of one or more inorganic substances which, when mixed with water, harden into a solid, rigid mass, Portland cement and gypsum being examples of such masses,

Continuity of the layers of fibrillated organic film essentially refers to a situation in which the various particles that make up the network structure extend from one edge of the product to one of the main dimensions of the product, such as the width or length of the product, or both. More generally, continuity means that the mesh structure cannot be mixed with the water-curable mass in a rotary mixer. The film with which satisfactory results can be obtained is so long that when placed in a rotary mixer it becomes a tangled mass which is largely separate from the water-curable mass. mass. Nor can the film be sprayed with a water-curable material in the same way as fiber cements and concretes are sprayed.

The invention is not based on the ability of the organic film in the mixture to absorb water, but does not exclude the use of such absorbents. When polypropylene is used, water absorption is virtually non-existent in a humid atmosphere. After immersion in water for 24 hours, the absorbance was measured to be less than 0.10% under the conditions specified in ASTM standard D 570-63.

The incorporation of the film into the product can be facilitated by the use of a dispersant which causes the formation of a suspension of water-curable particles and helps their penetration through the network in such a way that the components are firmly bonded together. In general, such dispersants suitable for this purpose are sulfonated polymeric substances such as low molecular weight resin, sulfonated melamine formaldehyde plastic or sulfonated naphthalene formaldehyde plastic.

However, the dispersant is not essential, since the fluidity of the material depends on the mechanical adhesion of its components to each other and on the very large surface area of the mesh structure per unit volume, which affects the susceptibility of the water-curable mass to rupture.

Most preferably, a plurality of impregnated mesh layers, which are a continuous, fibrillated organic film mesh structure, are joined to the pulp and compressed, flattened or vibrated in overlapping layers, usually less than 5 mm thick, by increasing the number of layers until the desired total product thickness is reached.

The network structure is preferably made of a polyolefin kiosk that has been stretched to orient its molecular structure so as to achieve high tensile strength and also increased modulus of elasticity. In current industrial applications of the polypropylene film, the stretching process provides an elongation of the polypropylene film 5 to 20 times the unstretched length.

Alternatively, the film can be prepared by performing fiber-forming crystallization.

After the stretching or crystallization process, the film is in a state where fibrillation begins and may fibrillate by further processing or by suitable mechanical treatment, such as roll rolling, as well as treatment of the polypropylene film used as a raw material for the binder additive.

The web structure produced is a flat, open, non-woven web made of polypropylene film, the elements of which consist of a film and not of monofilaments. However, the term "flat" should not be construed as meaning that the network structure is necessarily in one plane in the final product, although it is usually so flexible before being incorporated into the product that it conforms to the shape of the bed when placed on a flat surface.

Alternatively, the mesh structure forming the reinforcement may be woven in a manner sometimes referred to as "Leno" weaving, with the warp being duplicated in such a way that at each junction the weft passes under a double warp. The two warps are repeated before the next weft yarn passes again. This creates the advantage of creating a net that retains its shape when processed in industrial equipment, and the use of double weave promotes the formation of a mechanical bond between the water-curable mass and the mesh structure. The weave mesh structure thus has advantages in manufacturing. but on the other hand it has the disadvantage that it is more expensive and may require a larger amount of material to achieve similar properties, the warp and weft of "Leno" fabric as well as the non-woven mesh structures are formed of fibrillated 8 76544 but not stretched polypropylene.

However, the most preferred of the above-mentioned reinforcements is a stretched nonwoven web made of stretched film by mechanical fibrillation into a uniform structure as shown in Figure 1. One advantage of this nonwoven web structure is that it can be made of very thin films, as a result of which it becomes possible to increase the specific surface area of the material and to incorporate many more layers of reinforcement into a finished sheet of a certain thickness with a certain total amount of material. The thickness of the film may be in the range of 1-1000 microns, but thin films with a thickness in the range of 15-150 microns are most preferably used. However, the choice of thickness depends on the amount of mesh to be placed in the structure, i.e. the desired properties of the finished product. bond formation between the mass and the network structure, which apparently explains the good properties of the product, such as, among other things, the desired reduction in fracture length and spacing in the product exposed to fractures, polyolefins are the most preferred, but polyamides also have good properties and can be fibrillated to provide either a woven or nonwoven web structure.

Whereas the yeda-curable mass is most preferably ordinary Portland cement, which also contains a filler such as very fine sand and / or comminuted fuel ash, and the degree of fineness is important because otherwise there would be insufficient penetration between the mesh structure and the mass, resulting in a disadvantage; that gaps and weaknesses would arise. The fineness of the filler is a very important factor when a large number of mesh layers are formed, in which case the degree of fineness of the fines is selected according to the number of reinforcing mesh layers, 9 76544

The composition may also contain short fibers as an additive, which e.g. improve the surface quality of the finished product. However, such additives do not form part of the fibrillated organic network structure and are normally placed above and below the network structure.

The board, which is intended to replace an ordinary asbestos cement board, preferably has at least 6 or 7 layers of mesh, which make up 5-7% of the board volume, but even better strength properties can be obtained by increasing the number of mesh layers, and when a very thin film continuous mesh is used as a starting material. the number can be increased to several hundred and within certain limits the impact resistance and the area of the deformation curve in bending and the area of the stress-strain curve under tensile stress can be considerably better than with asbestos cement.

In the case of panels symmetrically corrugated like asbestos cements, it is generally desirable for most of the mesh layers to be oriented in the same direction as the corrugations, but for other uses it may be more advantageous to orient the mesh layers differently or even more differently in one and the same board. are not necessarily at right angles to each other. If the direction of the loading stress on the product in use is known in advance, it is of course most advantageous to orient most of the fibrils in accordance with this loading direction.

In the manufacture of sheets, it is advantageous if, after forming a certain amount of water-curable mass and reinforcing layers *, these are subjected to compression to provide a mechanical bond between the mass and the fibrils, and water can be removed under reduced pressure using a filter film. 10 76544 on methods of manufacturing concrete products.

Many products other than simple sheets can also be manufactured. Thus, multilayer mesh structures can be wrapped around different molds to provide the desired, out-of-shape products.

Various embodiments of the present invention are further illustrated by the following examples, which relate to the accompanying drawings, in which

Fig. 1 shows, when applied and isometrically, a sheet according to the present invention with a plurality of continuous, non-woven mesh layers of fibrillated film.

Fig. 2 is a diagram with an ordinate load (kN) and an abscissa deflection (mm), and further comprises a specimen with a mesh structure of a nonwoven, fibrillated film.

2

Fig. 3 is a diagram in which the ordinate is the tension (MN / m) -6 and the abscissa is the elongation x10, and further comprises a specimen containing a nonwoven, fibrillated polypropylene film.

Fig. 4 is a diagram in which the ordinate is the load (kN) and the abscissa is the deflection (mm), and further comprises a test piece of the same material as shown in Fig. 3, 2

Fig. 5 is a diagram in which the ordinate is the tension (MN / m) and the abscissa is the elongation at the original fracture site, and further comprises a specimen containing woven polypropylene.

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Fig. 6 is a diagram with the ordinate of the stress (MN / m) and the abscissa of the elongation x10 ® showing the elongation of the specimen of Fig. O after fracture, and

Fig. 7 is a diagram with the ordinate load (kN) and the abscissa deflection (mm), and further comprising a specimen containing a woven, fibrillated polypropylene film;

Example 1

The test piece to be subjected to the bending test was prepared by the method of the invention so as to contain 6% of its total volume of a continuous flat mesh structure of stretched fibrillated polypropylene film having a thickness of about 100 microns. The following weight ratios were selected to provide a water-curable mass: “cement 1.0, water (total) 0.34, ground fuel ash 0.25, fine sand that passed through a 600 micron screen, 0.19, and a dispersant (sulfonated melamine -formaldehyde plastic) 0,03,

The test piece was rectangular and its dimensions were 13.5 mm x 50 mm x 150 mm. The experiments were performed at a span of 135 mm and the results are shown in the diagram of Figure 2 with the ordinate load (kN) and the abscissa deflection (mm). The relatively high post-fracture flexibility is based on the interdependence of the continuous network structure and the cement matrix and the ability to carry the load even after the matrix fracture has occurred.

The load was removed at a stage when the deflection was about 6 mm, and the shape of the body was restored so that the final deflection remained 1.5 mm. No fractures were observed with the naked eye at the point of load on the specimen after the load was removed, but 12,76544 microscopic examinations revealed very fine fractures spaced 1 to 3 mm apart.

In Fig. 2, at the point where the load was removed, the modulus of fracture calculated in the conventional manner using 2 elastic analyzes was about 27 MN / m, but the maximum load had not been reached. Other similar samples have 2 achieved fracture modulus greater than 30 MN / m.

2

Figure 2 shows kN = 14.8 MN / m as the value of the fracture modulus.

Example 2

Although it is preferred that the proportion of reinforcement in the volume be greater than 5%, according to the present invention it is possible to achieve multiple fracture formation as a result of tensile and bending and an increase in flexural strength even with smaller amounts of continuous, smooth, nonwoven mesh structure.

A tensile test specimen (Figure 3) was prepared using the water-curable mass of Example 1 with 324 layers of a flat, open mesh structure of nonwoven, fibrillated polypropylene film. The thickness of each film was at the lower limit of the thickness range. The test piece was rectangular in cross-section and had dimensions of 15 mm x 30 mm x 280 mm, with about 22 layers of film per millimeter of thickness. The total volume of the film was 2.3% of the total volume of the test piece. The effective volume of the film in the direction of the tensile stress is difficult to determine in the case of flat, open mesh structures, but was presumably in the range of 1.5-2% in this example. The test piece was tested and the inlet sets are shown in Figure 3. The elasticity after fracture was considerable as in Example 1, 13 76544

Example 3

The bending specimen was made of the same material as in Example 2. The specimen was rectangular and had dimensions of 14.5 mm x 50.5 mm x 150.00 mm. The experiments were performed using a span of 135.0 mm and the results are shown in the diagram of Figure 4 with the ordinate load (kN) and the abscissa deflection. Increasing the load after fracture was possible based on what is described in Example 1. In this experiment, the modulus of fracture was 1 kN = 12.7 kN / m 2.

Example 4 In this example, a corrugated sheet was prepared and the composition of the water-curable mass was the same as in Example 1.

As a reinforcement, a woven material ("Leno fabric") made of a continuous, oriented, fibrillated polypropylene film having a mesh size of 3 mm mesh and having approximately two weft yarns per warp yarn was used. Six layers of mesh were used to form a 1.5 mm thick product. Four layers were placed so that the warp was parallel to the folds and two layers were placed so that the weft was parallel to the folds.

A finished plate with dimensions of 0.23 m xl, l m and corrugations 20 mm high was tested according to B, S, 690, Part 3, 1973, with which the plate withstood the required 334 Newton load. Cyclic loads were used, in which the load was initially 150 N, then 350 N, then 400 N, and finally 800 N. Three loads were applied to each load. At a load of 150 N, two minor fractures were formed: a load of 350 N had a fracture spacing of 10-40 mm, a load of 400 N had a reduced fracture spacing, and a load of 800 N had a significant deflection and fracture distances ranged from 3 to 6 inm.

Long-term load tests were performed on similar plates using a continuous uniformly distributed load of 0.75 kN / m for 27 days and 1.5 kN / m for the next 33 days. The residual deflection after unloading was less than 2 mm at a span of 0.93 m. The uniformly distributed load was added to 2 2 kN / m, with the curve showing the load as a function of deflection showing that a substantial fracture had occurred.

2

A continuously maintained load of 0.75 kN / m after rupture produced a creep-based change of 0.25 mm in 30 days. Uniformly distributed loads were as set forth in B.S. 5249, Part 14, 1975 for asbestos cement board.

Example '5' A tensile test specimen was prepared using the mixture of Example 1, as well as 150 layers of woven polypropylene ("Leno" fabric). The layers were subjected to compression while superimposed. The mesh structure accounted for 8% of the test piece volume.

The test piece was then tested and the results are shown in Figures 5 and 6. In both figures, the load 2-6 (MN / m) is shown as a function of the elongation x10. Figure 2 5 shows the initial modulus E = 21GN / m. Figure 5 shows the initial fracture properties, while Figure 6 shows the overall curve> showing the elongation after fracture. The left curve in Figure 6 is equivalent to Figure 5 on a different scale,

Example 6

The bending test piece was prepared using the strip mixture of Example 1 and 76 layers of woven polypropylene. The piece was rectangular and its dimensions were 500 x 100 x 74.5 mm. The load length of the test piece during the test was 406 mm. The experiments were performed and the obtained test results are shown in Fig. 7, where the load (kN) is shown as a function of deflection (mm). The modulus of fracture, calculated in the usual way using elastic analysis, in this figure is 10.32 MN / m at 10 kN-2. As is clear, the sample was progressively loaded with higher and higher loads, whereby a considerable increase in load endurance was achieved after fracture. .

The sheets produced by the method of the present invention are suitable for use for the purposes for which asbestos cement sheets have heretofore been used. In these, the plates are subjected to a bending load, in addition to which they may be subjected to shocks under certain conditions. It has been found that the sheets have sufficient rigidity as well as the desired pseudo-elasticity based on multiple fine cracking which, however, does not adversely affect the bending strength of the material. An additional advantage is that nails can be struck directly through a thin plate without cracks forming in the plate at locations far from the point of impact. The material is thus able to absorb a great deal of energy when it ruptures, either as a result of an impact or as a result of a slowly increasing load. In this respect, the material of the present invention is a very good improvement over previous asbestos cement products which tend to be crushed by impact. The maximum strength of the plate with respect to direct tensile stresses does not increase in the same proportion as with bending loads.

In the most preferred embodiment with several mesh layers, it has been possible to substantially eliminate the risk of weak points due to the lack of reinforcement. When using non-continuous images of fibers, there is a high risk of inhomogeneity.

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The present invention is applicable to corrugated, flat and asymmetrical plates, gutters, pipes that are not subjected to pressure, and rainwater conducting objects used in the building and construction industry. It is also possible that the material produced by the method according to the invention is used for the production of garden furniture, drains and cladding panels with expanded polystyrene. Alternatively, the material may include polystyrene beads to make a low bulk density insulation material.

The invention can furthermore be applied to stiffened concrete and other structural parts as a permanent coating, the purpose of which is not to affect the structural strength but instead to form fine cracks on the surface. This makes it possible to apply higher stresses to the beam reinforcement before the ultimate elongation at break is achieved compared to conventional stiffener concrete.

The boards of the present invention not only replace asbestos cement boards, but are also suitable both internally and externally for uses for which as-best cement products have not previously been able to be used.

Claims (14)

17 765 4 4 A sheet or other product comprising a network structure of organic matter connected to a water-cured mass, characterized in that the network structure is formed of a fibrillated organic film and in that the network structure is connected to the water-cured mass in a plurality of continuous overlapping layers. Product according to Claim 1, characterized in that the network structure is formed by a fibrillated, laterally stretched organic film. Product according to Claim 1 or 2, characterized in that the film forming the network structure is polypropylene. Product according to Claim 1 or 2, characterized in that the mesh structure is woven from elongated bodies of fibrillated organic film. Product according to one of Claims 1 to 3, characterized in that the network structure consists of several layers of fibrillated and stretched organic film and in that the product comprises an intermediate layer of water-cured mass or other substance. A method for producing a product according to any one of claims 1 to 5, wherein the network structure is formed of organic matter and this network structure is combined with a water-curable mass, after which the mass is cured, characterized in that the network structure is formed of a fibrillated organic film and combined with a water-curable mass. in several continuous overlapping layers. A method according to claim 6, characterized in that the network structure is obtained by expanding the fibrillated organic film. Process according to Claim 6 or 7, characterized in that the fibrillated organic film is a polyolefin film. is 7 6 5 4 4 Method according to one of Claims 6 to 8, characterized in that the fibrillated organic film is a stretched organic film. Process according to one of Claims 6 to 9, characterized in that the organic film is polypropylene. Method according to one of Claims 6 to 10, characterized in that the mesh layers are subjected to a mechanical action, such as vibration, compression or suction, during the manufacturing process. Method according to Claim 11, characterized in that the thickness of each layer of water-curable mass and mesh structure is 5 mm or less. Method according to one of Claims 6 to 12, characterized in that there is at least one intermediate layer between the water-curable mass and the water-curable mass or other material. Method according to one of Claims 6 and 8 to 13, characterized in that the mesh structure is woven from elongated bodies of fibrillated organic film. 19 76544