DE3401237C2 - - Google Patents

Description

The invention relates to a Composition according to the preamble of patent claim 1.

Such compositions or cardboards used as construction mainly used as material inorganic cement-based building materials, where no Asbestos is used.

Inorganic, hardened compositions, the cement as a binder and asbestos as a reinforcing agent are used in many ways. Asbestos finds the half application because it has the reinforcing effect of the organic composition significantly improved. As best also enables the inorganic hardened Composition using a Schöpf-Sieb-Her position procedure, such as B. the Hatschek system obtained, which is suitable for mass production. In this process, the sludge is contained Raw materials with the help of a scooping machine, e.g. B. means the Hatschek processing machine. The Basic formation that you get through such a process holds, is cured to a hardened inorganic Get composition. This manufacturing process becomes practical if the solids content of the asbestos 5 percent by weight.

However, the use of asbestos can be an environmental cause pollution, and continued further ver Use of asbestos creates serious problems public health.  

A plate product is already known, the auxiliary fibers based on cellulose contains (DE-OS 26 24 130). In this plate product is an aqueous Auf slurry of an inorganic cement and cellulose fibers with a Grinding degree from 20 to 300 ° C according to Canadian Standard Freeness, which is 40 to 85 ° SR corresponds, cured and optionally with an additional filler glass-like fibers. The proportion of cellulose fibers is here between 5 and 8 weight percent, which is the flammability of the plate products does not rule out yet. In addition, there is nothing about the length of the cellulose fibers testified so that even very small fibers are included, which are no more than Serve reinforcement for the composition.

The invention is therefore based on the object of a hardenable, asbestos-free To create composition that is not flammable, very firm and for the masses production is suitable.

This object is achieved in accordance with the features of patent claim 1.

The advantage achieved with the invention is in particular that the special proportion by weight and the special length of the cellulose fibers of the Schopper freeness without affecting the strength of the hardened zu composition can be optimized. After performing numerous sub searches have been found that non-flammable and extremely solid hardened Compositions can be mass produced by using a Process is used in which the pulp is cut by milling without being shortened to be split into small fibrils, in combination with untreated pulp that does not fibrillate, but only by means of disaggregation is processed. The present is based on the result of these investigations invention. A particular advantage of the invention is that the Products according to the invention in a single production process inorganic, cured compositions can be realized. With this The process uses pulp of 177 µm length and fibrillation exposed while under ge 10% by weight of the total pulp to achieve a Schopper freeness of 70 ° SR or higher.  The pulp thus contained in the sludge is total 1 to 5 weight percent of the total solids content of the sludge or Porridge set.

The invention is described in more detail below.

The degree of swelling and the filtration coefficient are defined as follows:

Filtration coefficient: coefficient per unit of filtration area during the Filtration at constant pressure

K = 2 V (d R / d v)
V : volume of the filtrate (cm³)
R : Filtration time (duration) (sec)

A 60 mesh wire mesh is used.  

In the method according to the invention, any type of water-based cement without any special restrictions be used. For example, Portland cement or Portland blast furnace cement can be used. As a wooden cell fabric is preferably bleached or unbleached Kraft pulp from coniferous or deciduous trees used. Waste paper, such as B. sulfite paper or kraft paper can, if used in large quantities, because of  the impurities contained in them are cause peaceful cement precipitation. However, since the fiber length is generally short and the These grades of paper are relatively large often used, but only in small quantities and too together with asbestos.

Such waste paper can also be used in the present case Invention find use as long as more than 60 Ge weight percent of the total proportion of wood pulp, which contains this waste paper, a fiber length of 590 microns or longer, as already mentioned above and if its Schopper freeness is within 40-95 ° SR is.

To achieve a grinding degree of 40 ° SR, there are two Process available: the pulp cutting and splitting into partial fibrils (fibrillation). The Cellulose cutting improves the grinding grads, but it is not suitable to use the hardened cement Reinforce composition. On the other hand The fibrillation of the pulp increases the meal degree, while at the same time the hardened cement Composition reinforced. The fibrillation must, however can be controlled, otherwise the pulp Continue cutting.

An essential aspect of the invention is that the pulp is fibrillated, the partial fibers However, that was cut short in the pulp den are limited so that they are in the lowest possible concentration.

In a certain method according to the invention  becomes pulp of conifers and / or deciduous trees used. The Schopper freeness of the pulp is brought to 70 ° SR or higher. The fiber content with a fiber length of less than 177 µm is less than 10% by weight of the total amount of the cell fabric.

Such pulp is made with an amount of 1-5 percent by weight based on the total amount Breis (hereinafter referred to only as%), ver turns. If the proportion of fibrillated pulp is less than 1% even if that is finely grained inorganic filler, which makes the filter possible reduced, added, it is impossible reduce the filter coefficient to the point which allows production according to the Hatschek system. On the other hand, if the fibrillated pulp is 5% of its Product, the product cannot meet the requirements non-combustibility requirements, whether production is probably feasible if the share of the other organic reinforcing fibers is viewed. The Schopper drainage level of the needle tree or deciduous pulp is below 40 ° SR, if it is crushed normally. If such a cell fabric with a share of less than 5% is, production is based on the Hatschek process impossible, even with a combined ver use of fine-grained, inorganic filler, that lowers the filtering ability. It means that because of the exceptionally good filtering ability (i.e. the drainage is too good) the cement grains in the filtrate Hatch. So it is an essential requirement during the generation (e.g. through Schöpf-Filtration) flammable hardened compositions that pulp,  which is so crushed that it can hold a 70 ° SR Has a degree of grinding in an amount of more than 1% is there.

As for the fiber length of the fibrillated pulp, so the crushing by a grinding machine, e.g. B. the PFI mill, the single disc mill or the double disc mill performed, and at the same time with the Fibrillation advances the process of trimming of the fibers.

It is necessary to crush the pulp so that the degree of dewatering or grinding of the Schopper increases becomes. However, if it is crushed too much, the Fibers cut into short pieces and can no longer serve as reinforcement for the hardening composition. For example, fibers are less than 177 µm in length almost no reinforcement effect; they are just in terms of increasing the Schopper freeness effective. That is why it is desirable to share this keep short fibers as low as possible.

As mentioned above, the invention uses a pulp with a fiber length of less than 177 µm in one Share of less than 10% of the total amount of ge whole amount of pulp used. The reason for this be is that if the proportion of this pulp exceeds the above-mentioned level, the water absorber ratio of the cured composition increases, resulting in a substantial reduction in strength results when the composition absorbs water. To the fibrillated pulp, which Freeness of more than 70 ° SR, a length of less than 177 µm and less than 10% of the total amount of the cell  is a pulp of less than 70 ° SR Schopper freeness can be added (unprocessed coniferous pulp, unprocessed deciduous Pulp, waste paper etc.). In other words, if the fine-grained inorganic filler that the filters ability, added, it is not necessary to only use the fibrillated pulp mentioned above turn. The other pulps with a Schopper Grind of less than 70 ° SR can also be found in Combination can be used within the the area in which the filtration coefficient of the pulp can be set to less than 5 cm⁴ / sec can.

The ratio for the combined use of Pulp above 70 ° SR and below 70 ° SR According to the invention, the Schopper freeness is 1: 4-5: 0 fixed. If strength and economy are taken into account 1: 1-2: 1 is preferable. In other methods according to the invention, conifers are used wood or deciduous wood pulp with a Schopper Freeness of 40-95 ° SR and a fiber length of more than 590 µm, which accounts for more than 60% of the total pulp Share. The concentration of such pulps, expressed as a percentage of the total solids content, is 1-5 percent by weight (hereinafter referred to as% cuts).

There are also coniferous or deciduous cellulose pulps used that only processed by means of disaggregation and which have a Schopper freeness of less than 45 ° SR. The concentration of the latter cell substances as a percentage of the total solids content 0.5-1%. In other words, if the one mentioned above  fibrillated pulp less than 1% of con is the filter coefficient not be reduced to a value that the Her position according to the Hatschek system not even if the filler that holds the filter decreased ability, along with the cell mentioned fabric is used. Even if the filtration coefficient can be reduced to the value that enables production using the Hatschek process light, is the proportion of cement grains that with the Water through the mesh of the cylinder net gives way to big, and it is impossible to use the products expected quality. Also kick problems during the manufacturing process, e.g. B. clogging the pipes. On the other hand is the manufacture feasible if the concentration of the above-mentioned fibrillated pulp exceeds 5%, but then the product does not meet the requirement of Non-flammability when the share of others increase organic fibers is considered.

In the case of combined use of untreated Pulp with a Schopper freeness of 40 ° SR or less, it allows concentration of less than 0.5% still, with the process of scooping Proceeding procedure; however, difficulties arise during the subsequent process step, d. H. when dehydrating the cake to the felt, if the ability to dehydrate becomes poor. During the Rolling up the cake on a manufacturing roller the excessively high water content can stick on the roll surface or an error in the shape cause attitude.  

On the other hand, if the concentration of the untreated If the pulp exceeds 1%, the filtration coefficient decreases cient, resulting in a high solids concentration in the filtrate, causing the cement to flow on a very small amount is reduced. Another after part found in connection with this case de, is that during the press molding of the clean sheet the springback effect when easing of pressure increases and the products obtained all have a low specific weight. As above already described, it is for the manufacture of the fiber-reinforced cement boards based on the Hatschek system necessary the fibrillated pulp in a con use a concentration of 1-5%. With fibrillated However, pulp alone has the disadvantage that because of the low drainage rate to the felt when Manufacture, roll and press, the products not the possess necessary gravity, although the manufacture by means of scooping seven.

In the present invention where 0.5-1% of the unhindered contained pulp (compared to the Process using only fibrillated pulp det) the drainage of the cake during the production carried out with greater effectiveness. Accordingly, products with high speci are obtained weight in which the pulp fibers and the Cement are mixed evenly and firmly.

The untreated pulp that ver is used is a coniferous pulp or a foliage tree pulp that is normally crushed and one Has a Schopper freeness of less than 40 ° SR. If this Untreated pulp is used alone  Hatschek's method is impractical, even if others Materials such as B. the filler, who added the. The result is the same, even if the An part of the previous untreated pulp used is increased to more than 0.5-1%, which corresponds to the range speaks, in which the inventive method is applied. In other words: the filterability is so big that the cement grains in the filtrate Hatch. This not only causes worse physi calic properties, but also undifferentiated graced liquid level. A production that one Difference in fluid level requires is not feasible under these circumstances. Just if the pulp that is strong up to 40-95 ° SR Schopper- Grind is crushed in conjunction with the un treated pulp, the hatchek System high density products with great effectiveness testify.

The fiber length of the fibrillated pulp is obtained, by using impact machines such as B. the PFI Mill, the single-disc mill or the double-disc Mill, beats. Along with fibrillation goes cutting the fibers further. It is necessary, Beat the pulp to reduce the Schopper freeness increase, but if you hit too hard, the fibers will shortened by cutting, making the reinforcement effect of the pulp for the hardening products ver lore goes. So shows z. B. the fibrillated pulp with a fiber length of less than 590 µm almost none Reinforcement effect more, but only an increase of the Schopper freeness. Therefore you should consider the proportion this short fiber pulp as much as possible limit.  

The reason why in this invention, the proportion of Pulp with a fiber length of 590 µm or longer is set at over 60% of all pulp, be is that if this pulp is below 60%, the water absorption rate of curing composition increases and strength the hardening composition because of the water absorption tion is reduced.

As for the inorganic fillers, so are used those that have a degree of swelling of more than three times. For example, anor ganic fillers such as sepiolite or Bentonite, which have a high degree of swelling when they are Absorb water. If such a filler too is used together with the pulp mentioned, both can be mixed with cement and water the filtration coefficient of the slurry or sludge can be reduced below 5 cm⁴ / sec, which ent ent speaks by using the basic formation when using of the Hatschek system. By the combined Use of the fibrillated pulp mentioned and of the expandable inorganic filler the degree of grinding is reduced (i.e. the flow of the Cement is improved). It is not known exactly why the degree of grinding lowers and the flow of cement is increased. However, it is believed that the swollen inorganic filler with the fine fibers of the fibrillier pulp in a satisfactory manner is looped, so that both have a networked structure when they are filtered. The reason why the Degree of swelling of the inorganic filler to the more is set as a threefold, this is: organic fillers with a degree of swelling of less  than being used three times, nothing is shown great effect in lowering the above Filtration coefficient. Furthermore, when the The proportion of the inorganic filler exceeds 5% Possibility of reducing the strength to (Erniedri strength due to water absorption).

Other fillers that triple one Have degree of swelling and used in the invention are crystalline or non-crystalline silica with an average grain size of less than 5 µm. If such a filler to the cell mentioned above added fabric and mixed with cement and water the filtration coefficient of the slurry or Mud further diminished, and the pulp can now be used for the products are processed. The filler enables a filtration coefficient in one Get area that is suitable for production even if the pulp's beating is limited has been. This provides performance for the pulp Hitting saved and product flexibility achieved. The composition of the materials can not only be changed by the pulp, but also through the filler, depending on the use product. Another advantage is that when crystalline or non-crystalline Silica with a grain size of less than 5 µm as filler is used, this with cement during curing reacts, which further strengthens the product.

As reinforcing fibers, in addition to the cell inorganic fibers such as glass fibers, carbon fibers, Steel fibers, wollastonite and organic fibers such as Vinyl, acrylic and polyethylene can be used.  

As an organic fiber, vinyl is preferable, while Wollastonite is preferred as the inorganic fiber. Among the vinyl fibers, those are advantageous which are partially uneven. It's common knowledge that of the organic fibers the vinyl fibers because of their hydrophilic group the one with the greatest effect when combined with cement and one is out signed reinforcement causes. The combined use of this fiber with the fibrillated pulp and the raw pulp gives another ver improvement in strength. The suspected reasons for the above effect is that the vinyl, if it is used alone has low affinity Cement has and tends to slip away. If ever but used together with the pulps mentioned it closely engages with the fibrillated cell fabric and with the untreated pulp that paves the way prevents slipping. If the vinyl used is one partially uneven surface, e.g. B. as a result heat treatment during spinning and after spinning, the tendency not to slip away, further improved.

As for the vinyl fibers, the thickness is 5-50 µm and a length of 3-10 mm are the preferred Areas. The preferred proportion of vinyl fibers is 0.3-2%. If the share is 2% in the normal porridge product tion system, it becomes difficult to get a homo gene dispersion of the fibers to achieve what a Ver pleasure in firmness. If on the other hand the proportion is less than 3%, the reinforcement insufficient effect. Especially in the uncured Condition becomes the property of keeping the shape inadequate.  

For wollastonite there is no special limit for prescribed the length, thickness and shape of its fibers, but it is of course desirable that wollastonite has the largest possible area ratio. The before the proportion of wollastonite that moves between 2-15%. If the proportion exceeds 15%, the Ver strengthening effect itself not degraded, but that specific weight of the curing composition lowers the reinforcing effect as a whole.

The porridge is made by mixing the above mentioned gear materials prepared with water. The preferred te concentration of the solids content of the pulp carries 4-15%, or even better, 6-10%. Is below 4% the production efficiency low, which leads to a min productivity leads. In addition, the festival portion of the pulp excreted, which leads to that it is possible to make a cured composition receive. However, if the solids content of the pulp is over 15%, the thickness of the processed cake uneven, which makes it difficult to get a homogeneous one to obtain curing composition.

In addition, the filtration coefficient for the sludge to be set below 5 cm 5 / sec because of such Numerical value is an absolute requirement for the introduction the production is based on the Hatschek system.

A porridge with the above composition, based on obtained in this way, is by means of the Hatschek Processing machine processed and made in layers pulled each other to the basic formation with the appropriate one To form thickness. By curing this basic formation a hardening composition is obtained.  

From the preceding description it can be seen that with the invention a very solid curing together can be mass-produced, even without using asbestos. Since the An low in pulp and fibrillation is carried out to a high degree, you get not just a non-combustible composition, son also a low water absorption, which results in a less reduction in strength with water absorption tion results.

Furthermore, the fine fibers that improve the Fibrillation revealed the adhesion between the Layers of processed products. Thus, the hardening composition also by destruction Frost resistance.

Examples and comparisons

The following are the descriptions of the examples of the present invention and examples of the Comparison given together.

Examples 1-24 and Comparative Examples 1-14 of inorganic curing composition were made from Raw materials made shown in Table 1 using the Hatschek system at which the Hatschek processing machine is used. The results of the test based on the examples was also carried out in Table 1 shown.  

Table 1

Examples and comparative examples

(When the pulp is fibrillated and cut)

Table 1 (continued)

Claims (12)

1. Curable, asbestos-free composition which is obtained by the Hatschek process from a slurry, the solids content of which is a mixture of comparatively small amounts of cellulose fibers and an inorganic binder, e.g. B. contains cement, characterized in that

• - The solids content of the slurry is 4 to 15 percent by weight;
• - Within this proportion of solids, the proportion of cellulose fibers is 1 to 5 percent by weight and
• - Within the proportion of cellulose fibers, those fibers that are 177 µm or less long do not make up more than 10 percent by weight.

2. Curable, asbestos-free composition according to claim 1, characterized records that a filler in the solids content of 4 to 15 weight percent with a triple degree of swelling is included. 3. Curable, asbestos-free composition according to claim 1, characterized records that the filler is sepiolite or bentonite, the proportion of Filler makes up 1 to 5 percent by weight of the total solids content. 4. Curable, asbestos-free composition according to claim 1, characterized records that the cellulose fibers have a length of 590 µm or more with a Have a Schopper freeness from 40 to 95 ° SR. 5. Curable, asbestos-free composition according to claim 1, characterized records that the cellulose is a bleached or unbleached cellulose of Is coniferous and / or deciduous. 6. Curable, asbestos-free composition according to claim 1, characterized records that in addition inorganic or organic reinforcing fibers are seen.   7. Curable, asbestos-free composition according to claim 6, characterized records that the reinforcing fibers consist of wollastonite. 8. Curable, asbestos-free composition according to claim 6, characterized records that the reinforcing fibers are made of vinyl. 9. Curable, asbestos-free composition according to claim 6, characterized records that the reinforcing fibers are made of acrylic. 10. Curable, asbestos-free composition according to claims 8 or 9, characterized in that the reinforcing fiber be made of vinyl or acrylic stands and has a thickness of 5 to 50 microns and a length of 3 to 10 mm. 11. Curable, asbestos-free composition according to claim 1, characterized records that the cellulose fibers are at least fibrillated. 12. Curable, asbestos-free composition according to claim 6, characterized indicates that the reinforcing fibers have a roughened surface.