DE2110599B2 - Process for the production of a glass fiber fleece by the wet fleece process - Google Patents

Description

The invention relates to a method for producing a glass fiber fleece, as described in the preamble of Claim is defined.

After using modern fiber production plants (DE-AS 13 01 019) the number of generated per unit Single glass threads were multiplied compared to the originally used rod drawing process, it was it is no longer possible to use these fiber production systems with very thin nonwovens according to the known one and proven dry process (DE-PS 12 70 496) to produce, as this is the production speed both mechanical and fluidic limits are set. It was therefore endeavored to the wet process, which has been tried and tested with cellulose and other natural fibers, also in glass fiber technology to be introduced (US-PS 34 41 792). As a well-known fiber raw material, fiber bundles were made from chopped up Glass silk strands or glass silk rovings are used, which are known to consist of a large number of elementary filaments exist of infinite lengths, which are combined in a largely parallel order to form a strand and are glued to one another by a binding agent. “The threads run such an intimate connection with each other, that later, chopped into stacks of the same length, only with difficulty in the original Allow individual fibers to open up.

Attempts have been made (US Pat. No. 27 19 330) to reduce the binder content to a minimum in order to achieve a To achieve better dissolution of the bundle into individual fibers in the water, but then occurred during the chopping process in addition to a high level of dust generation, premature splitting, which in no way favored the dissolution, it only led to the fibers becoming matted before they were added to the water, and then all the more were more difficult or impossible to unravel.

In addition to using stacks of chopped glass silk or glass silk rovings, you can also use ·> ο tries to chop so-called slivers, which are often also referred to as roving or roving, into sections to be used as fiber raw materials.

It was believed this is that sections of these glass staple fiber bands whose staple fibers ^hr by no binder are 'glued together better as a result of the loose and loose fiber structure in the water when fiber frets obtained from fiberglass! to single fibers

would dissolve.

However, it has been shown that the above-mentioned deficiency, which already occurs when using too stacks Chopped glass silk with a lower proportion of binder occur, especially here to an increased extent. This already begins with the chopping process, as the fiber sliver has different lengths in the chopped fiber bundles do not have fibers of the same length. In addition, the fibers are in the The tape is not parallel and becomes matted very strongly during the chopping or cutting process, often in addition to the already before the production of the sliver originating intimately matted connection of the individual fibers, so that a sufficient separation of the bundles into individual fibers in the water is no longer possible. The consequence is too here a strong formation of flakes, which appear in the finished web as clouds in an optically disruptive manner and close unacceptable fluctuations in basis weight, moisture and porosity with the resulting resulting defects.

In order to reduce these disadvantages, complex preparations of the fiber suspension have to be carried out with the help of additional units for deflaking the dissolving, storage and working chutes accepted, which are not only an extension of the Preparation and dissolving times with the same machine capacity, but also a considerably larger design of dissolving, storage and working chutes conditional, which increase costs on the system, on the building and finally on the production itself had an impact.

This last-mentioned disadvantage is to be remedied in a known method (US-PS 30 67 087), the deals with the production of paper from organic, hydrophobic fibers of greater length, with the tabular list of known hydrophobic fibers also includes glass fibers. In doing so, first Line provided, which means that dry fibers are already delivered in the correct length in the form of bales to unlock several successive nail bands and rollers, if necessary with one To spray wetting agents and in the constantly circulated dispersing agent, which is also mixed with wetting agents bring in. There they should be evenly in the with the help of baffle plates in the feed channel flowing medium are dispersed.

Alternatively, it is also provided that dry, endless fibers are fed in and one instead of the nail rollers Provide chopping device to the continuous filaments directly before introduction into the dispersion liquid to be shortened to the required length. This is then the generic manufacturing method.

However, this technique is also not suitable for the aforementioned difficulties regarding the insufficient To fix the dissolution of fiberglass sections made of fiberglass or fiber tape because the baffle plates provided in the feed channel, even with the addition of the wetting agents, which are actually quite useful are insufficient to the effect of the bonding agent bonding or the felting of the fibers in sufficient To pick up dimensions.

The invention was therefore based on the object of the aforementioned disadvantages, in particular the bad and the cuttability of dry glass thread leading to high levels of dust and the completely inadequate To fix the dispersibility of bonded or matted glass fibers with binders and one possibility

to create, which guarantees an optimal dissolution of the fiberglass structure in single fibers with little effort, in order to obtain an end product with the greatest possible uniformity of fiber distribution.

This object is achieved in the way that the glass thread is drawn out by pulling out the finest streams of glass Melting nozzles and winding on a drum are obtained, with the liquid treatment to improve the dispersibility in intensive spraying with binder-free water consists and after reaching a certain layer thickness glass thread is peeled off the drum and on be chopped the predetermined length.

Because the fibers are intensively wetted with water when they are produced, it is possible for further processing without any use of binders, first of all the necessary, ihi'e cohesion ensuring parallelism, the difficulties in hacking, in particular to avoid the generation of dust and still when it is introduced into the suspension liquid to achieve a practically complete resolution.

Although, as practice has shown, spraying the fibers with pure water for the realization of the invention is sufficient, of course, is an addition of those known and used for fiber suspension conventional wetting agents harmless, and in the event that the fiber bundle is not immediately after chopping be processed further and experience drying, even advantageous.

The process flow for realizing the invention is in its individual sections in Drawing shown schematically.

One can proceed so that in a conventional manner a plurality of parallel individual fibers 1 from Strömer liquid glass contained in a tub 2 provided with nozzles at the bottom, brought up to a rapidly rotating drum 3 and wound onto the circumference of the drum.

In order to achieve intensive wetting of all individual fibers, the drum surface is used according to the invention sprayed along their entire length with a stream of water, for example with a water fan 4, which at the same time also ensures good adhesion of the first fiber layer on the drum surface will.

The intensive moistening of the individual fibers causes their mutual cohesion while maintaining their parallelism when, after reaching a certain layer thickness, the drum is stopped and cut through the fiber layer in the longitudinal direction 5 of the drum and peeled off from the drum surface will. The layer can also be divided in the direction of the drum circumference 6 in order to do so to get smaller packets 7 of the moist fiber structure.

In the practical test, an average moisture content of the amount of fiber was found at the decrease measured in front of the drum of approx. 17%, which is between the Hei position and the Chopping time elapsed reduced to about 12-15%.

An excessive decrease in the moisture content can definitely be avoided by using the appropriate Counter measures during storage.

However, it is particularly advantageous to immediately transfer the still moist packets into a chopping device 8 bring where they are chopped into fiber structure 9 of preferably between 10 and 30 mm in length.

A further advantage of the use of moistened glass fibers in the one according to the invention is shown here Procedure. It consists in the brittleness that the glass fibers have in the dry state, and the z. B. leads to breaking and matting during transport and chopping, is avoided as well as for the operation annoying dust development.

The still moist, parallel single fiber structures 9 are then continuously, for. B. by a conveyor belt 10, preferably with the interposition of a metering device at regular intervals in a Introduced mixing vat U and mixed with the suspension medium 12, usually water.

The fact that this caused the cohesion of the fibers in the fiber structure and that as a suspension medium serving medium are the same, contributes to the rapid and complete dissolution of the cohesion of the fibers among themselves. This ensures a very intensive breakdown of the fibers, see above that the suspension, also referred to as "substance", from the mixing vat 11 by means of a pump 15 into the Working bucket 16 and before there by a pump 17, if necessary with the interposition of an end tipper 14 known design, into the line 22 of the circuit water, and through this heavily diluted in the Headbox 18 can be promoted.

From the dewatering chamber 19, the suspension medium arrives via a line 20 after passing it conventional filter devices in a storage tank 2t, from which the circulating water and by means of a pump 23 the water fed back into the mixing vat via a line 24 is withdrawn.

It is therefore possible according to the invention, even with the glass fibers which are known to be particularly difficult to suspend a continuous cycle of the suspension medium 12 from the mixing vat 11 via the working vat 16 and to achieve the headbox 18 back to the mixing chest 11, whereas previously with several mixing and Storage chutes had to work in such a way that a storage chute as a working chute with the The headbox was connected, while the other was connected to the fiber suspension coming from the mixing chest filled. During the time when the work bucket was running empty, with the help of Agitators or similar devices to unlock what is already in the mixing vat as well as possible strived for pretreated fiber structure, but did not achieve the thoroughness that the application of the Can achieve the method according to the invention.

1 sheet of drawings

Claims (1)

Claim: Process for the production of a glass fiber fleece by chopping up before being delivered continuously Endless threads, introduction of the dosed single fiber structure into a suspension medium and formation of a fleece on a moving screen surface after Wet fleece method, the fibers with a liquid ι ο before being introduced into the suspension were treated to improve dispersibility, characterized in that the Glass thread by pulling out the finest streams of glass from melting nozzles and winding it onto a drum obtained, the liquid treatment in an intensive spraying with binder-free There is water, and after reaching a certain layer thickness the glass threads from the Drum can be peeled off and chopped to the predetermined length.