EP0248309A2 - Process for the manufacture of flock fibres - Google Patents

Abstract

Flock is produced by inserting a flock cable into a sheath, in this form being subjected to at least one treatment bath, then removing the sheath and then cutting it into flock.

Description

The invention relates to a method for producing flock from synthetic fibers, in particular from polyacrylonitrile fibers and polyamide fibers.

The process of mechanical and electrostatic flocking is known and widely used. Fibers with a length of up to 15 mm, mainly in the range of up to 3 mm, which have a certain surface conductivity necessary for the electrostatic but also for the mechanical flocking process, are applied to a base provided with adhesives, so that a velor-like surface is produced becomes. The production of the flock fibers is described, for example, in Swiss Patent 426 723, DE-A-2 431 847 and DE-A-2 800 109. In the known methods, the flock cable, whether raw white, substance-dyed or dyed in the cable, is first cut to the fiber cut length desired for the method, then optionally dyed and then provided with the necessary electrostatic surface finish in several steps.

This process has a number of disadvantages. For example, washing, dyeing and preparation take place in several stages in a very long liquor ratio 1:15 to 1:40 depending on the fineness and cutting length of the flock. This requires a very large amount of water, the heating of which to the necessary temperatures requires a high amount of energy.

Since the flock is dyed and electrostatically treated with vigorous stirring and the flock particles are exposed to high shear stress, there are significant geometric changes in the flock fibers. The curvature of the flock particles can go so far that only low quality flocking is possible. With such a low quality flock it may be to achieve even a low flocking speed, which can result in economic disadvantages.

The object of the invention was to produce high-quality flock in a simple and inexpensive manner and to avoid the disadvantages described above.

The invention relates to a method for producing a flock for mechanical and / or electrostatic flocking from a flock cable and treating the flock in a treatment liquid, characterized in that the flock cable is introduced into a casing which is permeable to the liquid of the treatment bath, at least in this form subjected to a treatment bath and then cut into flock.

The casing is preferably removed before the flock is cut. However, it is also possible not to remove the sheath from the flock cable, but rather to cut it during the cutting process and then separate it from the flock, e.g. through sieving.

The flock cable preferably consists of a bundle of endless parallel fibers. Chemical fibers, in particular viscose, polyacrylonitrile, polyamide and polyester fibers, are particularly preferred. Polyacrylonitrile and polyamide are particularly preferred. The flock cable introduced into the tubular sheath preferably has a band titer of 25 ktex to 3000 ktex, in particular of 50 ktex to 1500 ktex. The sheath preferably consists of a flat structure of a different chemical composition than the flock cable. The shell should not be chemically changed during the treatment processes and should therefore consist of indifferent material. For example, it can be made from a perforated film or from a textile network, e.g. also consist of a knitwear, knitted fabric, a fabric, fleece or laid scrim. In a preferred embodiment, the cover consists of a knitted fabric or a circular knitted fabric made of polyester, polyamide or polypropylene.

The treatment bath is generally a dye bath or an finishing bath with textile auxiliaries for fiber preparation. Several of these baths can also be used one after the other. In a preferred embodiment, the flock cable in the tubular casing first subjected to a dye bath and then at least one bath with suitable textile auxiliaries. The dye bath can be a machine known per se for processing tubular endless textile material, for example a reel runner or a jet dyeing machine. The treatment in the dyebath takes place under conditions which are customary per se, but the water requirement can be reduced to 25 to 50% compared to the processes known from the aforementioned patents. The possible reduction in water consumption also saves energy and reduces the wastewater pollution of biological sewage treatment plants. The dyes customary and known for dyeing man-made fibers can be used.

Mineral salts, tannins, tannins, potassium antinonyl tartrate and anionic or non-ionic softening agents and combinations of these products are suitable as softening agents.

ONa


Sulfonierungsprodukte pflanzlicher und tierischer Öle, wie z.B. die Sulfonierungsprodukte von Olivenöl, Rizinusöl, Spermöl oder Rindertalg.Examples of suitable anion-active compounds are:
C₁₂-H₂₅OSO₃Na
C₁₈H₃₇OSO₃Na
C₁₂H₂₅O (CH₂CH₂O) ₄SO₃Na
[C₁₈H₃₅O (CH₂CH₂O) ₅] ₂

ONa


Sulfonation products of vegetable and animal oils, such as the sulfonation products of olive oil, castor oil, sperm oil or beef tallow.

Suitable non-ionic products have, for example, the formulas
C₁₈H₃₇CON (CH₂CH₂OH) ₂
C₁₈H₃₇COO (CH₂CH₂O) ₆H
C₁₈H₃₇O (CH₂CH₂O) ₂₀H
Anion-active compounds, for example the sulfates of higher molecular weight alcohols, are preferred.

The finish can be used in the same bathroom with e.g. same or lower temperature and the same pH value ("single bath") as well as subsequently in separate baths at different temperatures as the first treatment and different pH values ("separate bath").

The method according to the invention can be carried out, for example, as follows:

The flock cable is placed in the tubular sheath in a commercial reel runner in an aqueous solution containing a dye at 20 ° C to 40 ° C. To get an endless cable tie, the two will Ends of the sheath are connected in a suitable manner, for example by overlapping sewing together or swirling (splicing) of the cable ends.

The aqueous liquor has a pH between 4 and 8. The ratio of flock cable to aqueous liquor is between 1: 8 and 1:25. The flock cable is then dyed at suitable temperatures, between 80 ° and 100 ° C for polyacrylonitrile fibers and between 60 ° and 100 ° C for polyamide fibers.

After dyeing, the liquor temperature is reduced to 50-70 ° C and the chemicals required in the 1st finishing stage are added to the liquor one after the other. Potassium aluminum sulfate (alum), tannins, potassium timonyl tartrate (Brechweinstein) and acetic acid are preferred. After removing the aqueous liquor and introducing a new liquor, the cable is treated at temperatures between 15 and 50 ° C, preferably between 20-45 ° C, successively on the surface with anionic or nonionic plasticizers, potassium aluminum sulfate and alkali salts, preferably sodium chloride, ammonium sulfate or sodium acetate.

After the dyeing and finishing process has ended, the moist flock cable is removed from the dyeing device, preferably freed from the indifferent sheath surrounding to avoid fiber confusion and cut into flock in a manner known per se on flock cutting machines. The still moist clippings are then dried in a manner known per se, by sieving Irregularities freed and air-conditioned to be ready for use.

The process has a number of advantages that set it apart from the conventional process.

For example, the flock so produced is practically free from warping. This increases the areal density of the flocked articles considerably, for example up to 50%, and thus significantly increases the quality of the articles.

Alternatively, the production speed in the flocking process can be increased considerably in order to achieve an otherwise usual flock surface density.

In addition, due to the lack of curvature, finer titers can be used to produce and process a flock that is longer than that of standard goods.

Due to the possibility of coloring the flock cable in the tubular sheath even in pressurized commercial dyeing machines, e.g. To be able to carry out jet dyeing apparatus and thus achieve dyeing temperatures above 100 ° C., the time required for dyeing is considerably reduced. In addition, the authenticity of the dyeings can be improved and the bath exhaustion of the dyeing liquors can be increased, thereby reducing the environmental impact.

The water required for dyeing and finishing the flock can be 25-50% of the known original Ver driving are reduced while still improving the properties of the flock.

The mechanical effort for dyeing is less, which means that investments in the flock production plant can be reduced.

For example, there is no need for a centrifuge because the colored and coated flock cable only has a water content of 30-60% by squeezing and can be dried directly after cutting.

The process is described in the examples below, without exhausting the possibilities.

example 1

11 polyacrylonitrile flock tapes with a fiber titer of 0.6 dtex and a tape titer of 90 ktex are folded into a cable tie of 990 ktex and sewn into a polyester mesh. 10 linear meters of this cable are placed in a commercial dyeing reel with a capacity of 100 l and linked at the ends there. The cable is then dyed with a commercially available dye at 98-99 ° C for 1 hour.

After dyeing, the liquor is drained and cooled to 66 ° C. by adding cold water. This is followed by the two-stage finishing of the cable tape with textile aids.

step 1

After the liquor has been drained, the strip is dewatered to a residual moisture of approx. 50% and then reintroduced into the reel as described above. After heating the liquor from fresh water to 45 ° C, the second equipment stage is carried out:

Level 2

After draining the bath and draining the tape to a residual moisture of approx. 50%, after removing the covering, the tape is fed to a FLN 120 pecrum cutter and cut into flock with a length of 0.6 mm.

The still moist clippings are dried in a known manner in a cyclone dryer at 70 ° C, freed from irregularities by sieving and at 20 ° C, 65% rel. Air-conditioned humidity. The flock thus produced has a resistance of 8.10 8 ohms, measured according to DIN 54345, sheet 1, and has a very good flowability. It is largely free of curvature and with electrostatic flocking in an aqueous acrylate dispersion an area density of up to 50% is achieved than with conventionally produced flock (see table).

Example 2

10 polyacrylonitrile flock tapes with a fiber titer of 3.3 dtex and a band titer of 95 ktex become one Cable tape of 950 ktex folded and sewn into a polypropylene network, 15 linear meters of this cable are placed in a commercial dyeing reel with 120 l of water and linked there endlessly. The cable is then colored with a commercially available dye with a dyeing time of 1 hour at 98-99 ° C.

After dyeing, the liquor is cooled to 66 ° C by adding cold water. This is followed by the two-stage finishing of the cable tie:

step 1

After the liquor has been drained, the strip is dewatered to a residual moisture of approx. 50% and then reintroduced into the reel as described above. After the fleet has been heated to 45 ° C, the second equipment stage is carried out:

Level 2

After draining the bath and draining the tape to a residual moisture of approx. 50%, after removing the covering, the tape is cut into flock with a length of 1.5 mm.

The still moist clippings are dried in a known manner in a cyclone dryer at 70 ° C, freed from irregularities by sieving and at 20 ° C, 65% rel. Air-conditioned humidity. The flock thus produced has a resistance of 2.10 2 ohms measured in accordance with DIN 54345, sheet 1, and has a very good flowability. It is largely free of curvature and with electrostatic flocking in an aqueous acrylate dispersion an area density of up to 50% is achieved than with conventionally produced flock (see table).

Example 3

10 nylon 6 flock tapes with a fiber titer of 3.3 dtex and a tape titer of 100 ktex, folded into a cable tape of 1000 ktex and over a length of 10 m, are covered with a polyester mesh as described in Example 1 and placed in the dyeing reel introduced and then colored with a commercially available dye. After a short lead at 40 ° C, the mixture is heated to 98 ° C in 30 min and then dyed for 30 min.

After dyeing, the liquor is cooled to 66 ° C by adding cold H₂O and the cable band is equipped in two stages:

step 1

After draining the liquor and dewatering the cable tape to 50% residual moisture, the flock tape is again introduced into the dyeing reel as described in Example 1 and further equipped at 40 ° C.

Level 2

After squeezing the flock tape to a residual moisture of approx. 40%, after removing the sheathing, the tape is fed to a flock cutting machine and cut into flock with a length of 1.25 mm. The moist clippings are then further treated as described in Example 1.

After air conditioning, the flock has a surface resistance of 6.10⁷ ohms, has good free-flowing properties and good jumping ability in the electrical high-voltage field. The flock is largely free from warping. Flocking carried out in an acrylic dispersion also shows a higher flocking density here than with a flock produced by conventional methods (see table).

Comparative Example 4

10 polyacrylonitrile flock tapes with a fiber titer of 3.3 dtex and a band titer of 95 ktex are cut to a flock with a length of 1.5 mm on a flock cutting machine of the type described in Example 2. The flock is then dyed in a stainless steel container with a liquor ratio of 1:30 with intensive stirring by means of a metallic paddle stirrer introduced into the water flock dispersion, as described in Example 2. In order to prevent the dyeing liquor from foaming near the boiling point, the dyeing temperature is limited to a maximum of 97 ° C. This extends the dyeing time compared to Example 2 to 2 hours. After the dye has been absorbed by the fibers, the temperature of the liquor is reduced to 66 ° C. by adding cold water and the flock is gradually equipped with the products described in Example 2 in two stages:

step 1

After the liquor has been drained, the flock is dewatered in a centrifuge to a residual moisture of 20%, then reintroduced into the container and treated in stage 2 in the same liquor ratio with the finishing products described in Example 2. Subsequently, the flock is again dewatered in a centrifuge and dried in a known manner in a cyclone dryer at 70 ° C, freed from irregularities by sieving and at 20 ° C and 65% rel. Air-conditioned humidity. The flock has a resistance of 9.10⁶ ohms and is only moderately free-flowing. The majority of the flock particles have changed greatly in their geometric shape, i.e. curved. bent or curled several times. With electrostatic flocking in an aqueous acrylate dispersion, the surface density is 83 g / m².

Comparative Example 5

11 polyacrylonitrile flock tapes with a fiber titer of 0.6 dtex and a tape titer of 90 ktex are opened cut a flock cutting machine as described in Example 1 into a flock with a length of 0.6 mm. The flock is then dyed in a liquor ratio of 1:40, as described in Example 4, and electrostatically treated. After air conditioning, the flock has a resistance of 5.10⁶ ohms. As a result of the strong change in the flock geometry, which can be seen under the microscope, of practically all flock particles, the flock has poor pourability. When flocking in an aqueous acrylic dispersion, a surface density of 35 g / m² is achieved.

Comparative Example 6

10 nylon 6 flock tapes with a fiber titer of 3.3 dtex and a tape titer of 100 ktex are folded into a cable tie of 1,000 ktex and cut into flock with a length of 1.25 mm using a flock cutting machine as described in Example 1. The flock is then dyed and finished in a liquor ratio of 1:20 at a temperature of 85 ° C. as described in Example 4. After air conditioning, the flock has a resistance of 4.10⁶ ohms and is only moderately free-flowing. A large part of the flock particles is slightly curved. When flocking in an aqueous acrylic dispersion, a surface density of 105 g / m² is achieved.

Flocking of substrates

To assess the areal density of the flock during flocking, the flock produced using the example comparable flocking tests were carried out. For this purpose, a hydrophobized canvas binding made of a cotton / polyester yarn 50/50 was coated with a commercially thickened dispersion of a polyacrylic acid ester copolymer in a layer thickness of 300 μm.

The coated textile prepared in this way was positioned on a vibrating metal plate. Between the coated textile and the dosing sieve that received the flock was a metal electrode made of a sieve mesh at a distance of 100 mm from the textile, for example with a mesh size of 4 × 7 mm. A voltage of 40 kV was applied to the electrode using a Static 90 high-voltage electrostat, from Maag & Schenk, which corresponds to a field strength of 4 kV / cm. Flocking was carried out for 1 min. The flocked fabric was then dried in a hot air oven at a temperature of 160 ° C. for 15 minutes and the flocking adhesive was crosslinked. The flocked textile was freed from loose loose flock by thorough vacuuming with a powerful industrial vacuum cleaner. The weight per unit area of the flock was determined according to the usual methods.

The following table contains the basis weights determined using the flock produced as an example.

Claims (6)

1. A method for producing a flock for mechanical and / or electrostatic flocking from a flock cable and treating the flock in a treatment liquid, characterized in that the flock cable is introduced into a shell permeable to the liquid of the treatment bath, in this form at least one treatment bath subjected and then cut into flock. 2. The method according to claim 1, characterized in that a flock cable made of chemical fibers is used. 3. The method according to claim 1, characterized in that a flock cable made of synthetic fibers is used. 4. The method according to claim 1, characterized in that the treatment of the flock cable comprises dyeing and equipping the flock cable with textile auxiliaries. 5. The method according to claim 1, characterized in that a tubular sheet made of polyester, polyamide or polypropylene is used as the permeable sheath. 6. Flock, produced according to methods 1 to 5.