DE2624130A1 - METHOD FOR MANUFACTURING ARTIFICIAL FIBER PRODUCTS - Google Patents

Description

MÜLLER-BOR ^ -GROEiSfING REUIEL SCHÖN-HERTEL

PATEST LAWYERS

262U3Q

DR. WOLFGANG MÜLUER-BORt

(PATENT ADVOCATE FROM 1927-1975}

m Λ -iZrO HANS W. GROENING, DlPU-ING.

-L 1 JOO DR. PAUL DEUFEL. DIPL.-CHEM.

DR. ALFRED SCHÖN, DIPL.-CHEM. WERNER HERTEL. DIPL.-PHYS.

May 28, 1976

TAG CONSTRUCTION MATERIALS LIMITED
Manchester M2 2EA, England

Process for making man-made fiber products

609851/0985

MUNICH 80 ■ SIEBERTSTR. 4 POST BOX 8G07S0 CABLE: MCEBOPAT TEL. (089) 471079 · TELEX 5-22659

Process for making man-made fiber products

The invention relates to the manufacture of artificial fiber products, for example from cardboard and webs, with the aid of a process in which from an aqueous slurry a layer is formed on the surface of a rotary screen.

Such processes have heretofore been carried out using a slurry containing asbestos fibers and cement, optionally together with modifiers, fillers and the like, which serve to increase the density control of the end product. In the most common of such processes, asbestos and cement are mixed and with one A large amount of water is stirred to form a thin slurry which is then stored in one under stirring container known as a "cloth chest". This container represents a storage vessel from which the slurry charge is made taken, diluted with water and placed in one or more vats, in each of which a sieve cylinder is rotated, is fed in. Each of these cylinders takes the slurry as a continuous, thin, wet layer, the excess water runs off through the mesh of the sieve, and the layer is applied to an endless! by which it is transported to a rotating cylinder, onto which it is transferred and wound. The coating on the cylinder builds up layer by layer until the required thickness is achieved. To make a flat web becomes the sheet product on the cylinder (now commonly referred to as the forming roll) axially cut when it has reached the required thickness.

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Attempts to completely replace the asbestos fiber with glass-like fiber have so far "failed because the physical Properties of fiberglass differ from those of asbestos are so fundamentally different that the formation of a coherent Web on the rotary screen is extremely difficult, if not impossible.

According to the invention a process is provided for the production of fiber-reinforced cardboard and board products from an aqueous slurry by forming a layer on the surface of a rotary screen, from which the layer is then removed, which is characterized in that the aqueous slurry is made from water, an inorganic binder and 1/2 to 20 % glass fiber along with a small amount of non-asbestos auxiliary fiber having an average diameter of less than 3 microns and a freeness freeness in the range of 20-300 degrees. The percentage of fiberglass relates to the end product.

The term "Canadian Standard Freeness "(CSF) refers to the standard web formation test commonly used in the paper making industry is applied and after which z. B. a raw cellu- losepulpe a CSF of 700 to 900 ° and a very heavily digested papermaking cellulose pulp a CSF of has about 300 °.

The vitreous fiber can be glass fiber or mineral wool or a mixture thereof. The expression "Mineral wool" includes both slag wool / rock wool. When using fiberglass, the stack length is preferably on the order of 2 1/2 cm or less, with a length of 1 1/4 cm being particularly preferred.

6098 B 1/098 5 _{0R | G} , _{NAU | NSPECTH)}

The mineral wool can, if necessary, be pretreated to reduce its pile length, e.g. B. by the fact that they is subjected to a meal treatment.

The inorganic binder can be a hydraulic one Act binders, e.g. B. Ordinary Portland cement (O.P. cement), and in this case it turns out to be particularly advantageous if the glassy fiber is either alkali-resistant or at least pretreated to to reduce their susceptibility to attack by alkali. The binder can also be a powdered one Fuel stand included.

The non-asbestos auxiliary fiber is is preferably a cellulosic material, usually in the form of a pulp; Is that the case, thus the process expediently comprises a refining pretreatment in order to give the pulp the desired degree of digestion give, corresponding to a Canadian Standard Freeness value in the range of 20 to 300 °, with 150 ° in practice prove to be very useful. In conventional paper production, it is known that CSF values of less than 300 ° are in the Usually classified as very low. In contrast, the method according to the invention works very well at CSF values of 150 ° or even lower. Provided that the surface area properties of the auxiliary fiber asbestos are at least similar to those of asbestos or cellulose fiber, but other materials can also be used according to the invention be used.

Although the characteristic "comparatively small amounts" contents of up to 49 G-ew .- ^, other requirements, z. B. the requirement for non-flammability, the applicable Limit the amount to much lower values, e.g. B. to $ 5 or $ 10.

609851/0985

If appropriate, density modifiers, z. B. perlite, kaolin and / or kieselguhr, are added to the density of the artificial finished product in the for one appropriate area for specific use.

It is also possible to add free silica-containing materials for the specific purpose that they come in handy react with all the free lime that is released when the binder hardens. This is particularly true Methods too where hydraulic cement is used as the binder and where the binder is autoclaved is brought to harden. Free lime would of course tend to be the glass fiber component of the artificial fiber product if no attempt is made to minimize its effect.

The material removed from the rotary screen is naturally located in a wet state and the process according to the invention therefore generally comprises the process step of Curing of the binder, e.g. B. by air drying, autoclaving or oven drying, d. H. Heating in one Oven to make the final product. Optionally, the moist products can be shaped and / or cut or trimmed before the binder is allowed to harden. After the binder has hardened, the Cardboard is sanded or otherwise prepared for sale and / or use.

The invention thus also relates to asbestos-free cardboard products which have been produced by the specified method.

The following examples are intended to explain the invention in more detail.

6098 51/0985

Example Ί

It became a slurry of the following composition manufactured:

Weight -fa

alkali-resistant glass fiber (1 I / 4 cm staple length) 2

Alkaline-resistant mxneral wool fiber (pretreated by grinding) 10

bleached kraft paper pulp (refined on

130 - 150 ° CSF) 5

common portland cement 50

Kieselguhr 13

Perlite 10

Kaolin 10

The entry was mixed with water in a Mahlholländer on a semi-industrial scale (pilot plant scale), 125 l of water were required for 27 kg of Hollander batch. The mixing time was on the order of 10 to 15 minutes, including a 5 minute residence time after adding the glass fiber to the other components. This "procedure was chosen to ensure thorough dispersion of the glass fiber. The water temperature ranged from 30 to 35 ° C.

The slurry was then run on a handmade machine and made into paperboard products that were on for 7 days air matured and then oven dried at 100 for 24 hours. The average MOR-Yferte (at a standard density of about 720 kg / m- *), which applies to all Experiments carried out with this basic load were obtained

609851/098 5

den, varied from 5 »5 to 5» 8 If / mm depending on the operating conditions used on the machine. These values correspond to the British Standard Specification 3536 for insulation boards. The notched impact strength of the paperboard showed a substantial increase compared to the usual Asbestos-based paperboard, but the interlayer bond and stiffness of the paperboards were not as good. Equivalent or improved behavior in tests for freeze / thaw stability, Water absorption and dimensional stability found.

Example 2

A slurry was made up of ordinary portland cement (50 wt%) and a mixture of approximately equal parts of fibrous cellulose and inorganic filler (mainly kaolin), as related to Example 1 described.

Paperboard made from this slurry on the handmade machine had an average MOR value of 4 »98 N / mm at a dry density of 870 kg / m.

Example 3

Flat webs were made as described above under Use of a charge of the following composition:

alkali-resistant glass fiber of 1.2 cm staple length 1.5

Kraft pulp (GSF) 5

ordinary portland cement 93 »5

609851/0985

■ J.

The product obtained had a density of 1250 kg / m ^ and a modulus of rigidity of 17.1 MN / m.

Example 4

Separation panels were prepared using the same procedure from a batch of the following composition:

alkali-resistant glass fiber with 1.2 cm staple length 2.0

Kraft pulp (CSF) 8.0

ordinary portland cement 89.66 pigment 0.34

The products obtained had a density of 1095 kg / m and a rigidity modulus of 22.2 MN / m.

609851/0985

Claims (12)

Claims 1 · Process for the production of fiber-reinforced cardboard and Plate products from an aqueous slurry by forming a layer on the surface of a rotary screen, from which the layer is subsequently removed, characterized in that the aqueous slurry is made from water, an inorganic binder and, based on the end product, ½ Ms 20% by weight vitreous Fibers together with a comparatively small amount of non-asbestos auxiliary fibers average diameter of less than 3 microns and a freeness in the range of 20 to 300 ° according to Canadian Standard Preeness used. 2. The method according to claim 1, characterized in that one does not consist of asbestos auxiliary fibers such Cellulose based used. 3 · The method according to claims 1 or 2, characterized in that the auxiliary fibers not consisting of asbestos in a preceding process stage to a degree of grinding unlocks from 20 to 300 ° according to the Canadian Standard Preeness before the slurry is formed. 4. Process according to Claims 1 to 3, characterized in that glass fibers of a staple length are used as glass-like fibers on the order of an inch or less is used. 5. The method according to claim 4 »characterized in that glass fibers with a staple length of about 1.25 cm are used. 609851/0985 -t- 2624 I 3ΰ - ok 6. The method according to claim 3, characterized in that mineral wool is used as vitreous fibers. 7. The method according to claim 6, characterized in that the mineral wool fibers are pretreated in a preceding process step to reduce their staple length. 8. The method according to claims 1 to 3 »characterized in that that mixtures of glass and mineral wool fibers are used as glassy fibers. 9. The method according to claim 8, characterized in that one glass fibers with a staple length according to claims 4 or 5 and mineral wool fibers that reduce their staple length are pretreated according to claim 7, used. 10. The method according to claims 1 to 9, characterized in that the slurry is a density modification filler clogs. 11. The method according to claims 1 to 10, characterized in that after removal of the layer from the surface of the Rotary sieve causes the binding agent to harden. 12. The method according to claim 11, characterized in that the curing of the binder by autoclaving of the moist product. • t 609851/0985