US3543721A - Process and apparatus for the electrostatic flocking of textile material - Google Patents

Description

United States Patent [54] PROCESS AND APPARATUS FOR THE ELECTROSTATIC FLOCKING 0F TEXTILE MATERIAL 11 Claims, 3 Drawing Figs.

[52] U.S.Cl. 118/638;

117/17: 118/624 [51] Int. Cl B05b 5/02 [50] Field of Search 1 18/624,

[56] References Cited UNITED STATES PATENTS 2,254,016 8/1941 Melton et a1 l18/638X 2,274,726 3/1942 Melton l18/638X 2,276,328 3/1942 Melton et a1 117/17X 2,328,577 9/1943 Oglesby 118/638X /0 2f Zia 27 29 Primary Examiner-Peter F eldman Attorney-Michael S. Striker ABSTRACT: Apparatus are provided for the electrostatic flocking of textile material including textile material in the form of filaments or yarns. The textile material is coated with adhesive and past into an atmosphere of flock material generated by an electrostatic field of high intensity. The electrostatic field is produced by a main electrode and a complementary electrode of opposite polarity and a separate activating electrode having the same polarity as the main electrode, is disposed adjacent to but not in contact with the main electrode. The activating electrode is charged to a greater potential than the main electrode. The adhesivecoated material is passed between the complementary electrode and the main and activating electrodes so that flock material is deposited onto the material. In order to ensure that the flock material is deposited uniformly onto the adhesive-coated material, the flock material is conveyed between the electrodes on an endless belt in such a way that there is a greater amount of flock material conveyed on the outer portions of the belt than on the centre portion of the belt.

22 lid /4 atented Dec. 1, m0 3,543,721

Sheet 1 of 2 Fig.

l lnven/or: HRH 1,

Flocked filaments and yarns are outstandingly suitable for the production of striking, modern fabric which on the one hand due to their high bulk possess the warmth, appearance and handle of velvets and plush fabrics, but on the other hand possess the resistance to abrasion, soiling, action of chemicals, etc. which is inherent in synthetic fibres.

The production of flocked filaments and yarns however causes considerable difficulties because the coating of flock must be absolutely uniform in both the longitudinal and transverse directions of the yarn since otherwise stripes and other irregularities can be detected in the finished fabric. The flocking of the yarn must also be capable of being carried out in an economic manner since mass produced yarns will not tolerate high production costs. There is also the additional requirement that differences in the materials to be processed must not appreciably impair the practicability of the process, if different qualities are required. A further requirement which must also be fulfilled comprises controlling the flocking material in the flocking process so that no soiling of the surroundings of the flocking apparatus occurs. it is further required that all flock material should be directed in the flocking process to the yarn to be processed, that is to say that no flock material should circulate in the apparatus.

in prior processes for the electrostatic flocking of finished goods, such as, for example, hangings or carpets, the flock is accelerated from beneath upwardly towards the goods under the influence of an electrostatic field. The flock lies on an earthed plate or is conducted on a conveyor belt over such a plate. Above the earthed flock there is arranged a charged grid and the earthed goods are located above the grid. Between the grid and the two earthed plates an electrostatic field develops, so that the uppermost layer of flock is attracted upwardly from the conveyor belt. in flowing through the grid the flock receives a high voltage charge of the same polarity as the grid and is repelled by the sieve and attracted by the upper earthed plate. The flock is then deposited onto the adhesive coating situated on the under side of the goods. This known process however possesses various disadvantages which could not be removed hitherto. More especially the conveying of the flock in the electric field is not sufficiently reliable for the uniform flocking of textile material in the form of filaments or yarns.

SUMMARY OF THE INVENTION It has now been found that the various disadvantages of known electrostaticflocking processes can be overcome by subjecting the flock material to the action of a high-tension electric field which is generated between an electrode arranged above the threads and an activating electrode of opposite polarity situated beneath the conveyor belt carrying the flock material, the activating electrode being charged to a greater potential than an adjacent main electrode which is also arranged beneath the conveyor belt and has the same polarity as the activating electrode.

By virtue of the provision of the activating electrode a whirling-up of the flock material arriving on the conveyor belt is produced, so that the flock material forms a dense, uniform cloud. The electrostatic field existing between the main electrodeand the complementary electrode arranged above the goods to be flocked, which field has a lower intensity, serves to project the flock particles suspended as a homogeneous cloud in oriented fashion into the adhesive-coated yarns. The goods produced according to the process in accordance with the invention are distinguished by surprising complete uniformity. An additional surprising effect which is achieved by the process according to the invention consists in that, by reason of the initial formation of a suspension of individual particles of the flock material, the flock is entirely coated onto the yarns without leaving any residualflock material. Therefore no flock material penetrates to the exterior, of the apparatus,

although the process can be carried out within a very short distance on the yarn.

The apparatus proposed for carrying out the process is characterised essentially in that the electrodes connected to a high-density tension source are arranged beneath the belt which supplies the flock material and above the textile material to be flocked, of which electrodes the lower is made in two parts and consists of an activating electrode and a main electrode, the two electrode parts consisting of bars or wires arranged transversely of the direction of travel of the textile material, while the upper complementary electrode is formed by a continuous metal plate.

In contrastto the use of grid electrodes as hitherto, a substantially better orientation of the flock particles accelerated in the electrostatic field is obtained. It has appeared here that for the production of a satisfactory flock coating lower potentials are necessary than with the apparatuses hitherto, and that less importance than hitherto pertains to the maintenance of a specific room climate, especially as regards air humidity.

According to a further advantageous proposal of the invention the activating electrode is connected to negative potential which amounts to about percent -l50 percent of the potential applied to the main electrode. The complementary electrode is preferably made from a polished brass plate. The complementary electrode is here connected to positive high tension, which corresponds in amount approximately to the negative potential on the main electrode.

Considered in the direction of travel of the textile material the activating electrode extends approximately only over half the distance of the main electrode. This can be achieved in a simple manner by the fact that the activating electrode consists of about half as many bars or wires as the main electrode.

The activating electrode is charged to about -32 to 60 KV, the main electrode to about 40 KV and the complementary electrode to about +30 to 45 KV. In this working range a uniform cloud of flock material develops in the region of the activating electrode, while by variation of the individual potentials one has the facility of restoring uniformity when disturbed. A sign of an incorrectly selected potential is for example when streaks or stripes form in the cloud of whirled-up particles of flock material. Such phenomena disappear immediately however by variation of the potential at the electrodes and the uniformity of the cloud, which obviously substantially depends upon the uniformity of the flocking itself, is restored.

In passing through the electrostatic field the conveyor belt unavoidably also receives a certain charge, although the belt is produced from electrically nonconductive material. So that no difficulties occur in the delivery of the flock material on to the conveyor belt from the reservoir by reason of electrostatic residual charges, the endless conveyor belt, which can be made from spub glass fibre, is expediently earthed before the entry into and after the exit from the flocking zone.

The means for earthing the belt may comprise cylinders which reverse the conveyor belt and/or special scrapers on the belt.

So that the electrostatic field generated by the lower electrodes can act with optimum power upon the flock material lying on the conveyor belt, the conveyor belt will advantageously be slldingly guided in contact with the wires or bars forming the activating and main electrodes. it might be considered that in order to form a uniform cloud of flock particles, it would be desirable to provide most uniform possible layer of flock material on the conveyor belt. However, it has been found that the acceleration effect of the electric field is greater in the middle group of the filaments or yarns than at the outer edges. It has also been observed that the flock material is drawn from the edges of the conveyor belt into the middle of the flocking chamber. While this in fact gives the advantage that all the material lying on the conveyor belt is taken up entirely, it must however be ensured that not too little flock material is available for coating the outer filaments or yarns.

This difficulty can be overcome by depositing on the conveyor belt relatively more flock material in the marginal zones than in the middle region. This can be achieved by depositing the flock material onto the conveyor from a reservoir whose base is formed as a sieve, the openings in the sieve being larger in the regions disposed above the middle of the conveyor belt than in the region disposed above the marginal zones of the belt. A brush mounted on a horizontal axis is arranged to brush the flock material through the sieve. Preferably the reservoir is earthed.

So that the most uniform possible transition from the more heavily coated marginal zones of the conveyor belt to the somewhat more lightly coated middle part is achieved, the sieve bottom of the reservoir expediently consists of three sieve bottom parts lying side-by-side in the transverse direction of the conveyor belt, of which the outer parts have a larger aperture width than the part lying in the middle and in which the abutment edges situated between the sieve bottom parts extend obliquely of the direction of travel of theconveyor belt. Thus the individual sieve bottom parts have a somewhat trapezoidal outline in plan view.

BRIEF DESCRIPTION OF DRAWINGS FIG. I is a side elevation of the apparatus according to the invention;

FIG. 2 is a section through FIG. 1 along the line II-II; and

FIG. 3 shows a reduced plan view of the apparatus shown in FIG, I.

DESCRIPTION OF PREFERRED EMBODIMENT The apparatus according to the invention consists of a bench-type frame I, over the top of which an endless belt 8 for supplying the flock material is conducted. On the upper side of the frame an activating electrode 2 is arranged, and behind this in the direction of travel of the conveyor belt a main electrode 3 is arranged, both electrodes being located beneath the belt $3. The first electrode 2 is separated from the main electrode 3 by a distance A.

The bench-type frame is provided with a hood 4 which forms a downwardly open box in the two ends of which openings are cut at 4a and 4b through which the textile material M in the form of filaments or yarns to be flocked enters and leaves the flocking chamber formed beneath the hood 4-. In the interior of the hood 4 above the material M a complementary electrode 5 is mounted for adjustment in height with the aid of upwardly directed projections 6. The electrode 5 consists in the embodiment illustrated of a polished brass plate, in the middle region of which a vibrator 7 is arranged. The purpose of the vibrator 7 is to shake loose any flock which has settled firmly on the electrode 5.

As already mentioned, the flock material consisting of line short fibres is conveyed on the endless conveyor belt 8 driven in the direction of the arrow shown in FIG. I. In the embodiment as described, the conveyor belt consists of spun glass fibre. The conveyor belt 8 is conducted at the beginning of the flocking chamber formed beneath the hood 4 over a first roll 9 and at the end of the mentioned flocking chamber over a second roll I0. After running around the roll 10 the belt passes to a scraper II, which removes any residue of flocking material which may have remained adhering to the belt, but the additional purpose of the scraper II consists in earthing the belt 8.

The conveyor belt 8 runs over a support roller I2, mounted in the bench-type frame I and adjustable to produce the requisite belt tension, and then passes through a drive roller I3 before which there is placed an earthing roller Ilia bearing against the belt, which also can be used to regulate the belt tension.

I4 designates a drive motor which serves both to operate the belt It and to drive auxiliary devices which are to be described hereinafter. From the motor Id a first chain drive leads to the drive roller I3. A further chain or belt drive 18 connects the motor Id with the shaft of a rotating brush I? which is mounted in an earthed reservoir Id arranged above the beginning of the conveyor belt 8. The reservoir I? from which flock material is charged on to the belt $3 comprises a sieve bottom I9, the openings of which are adapted to the thickness and length of the flocking fibres. At the upper end of the reservoir Iii there is a filling hopper Zii and a distributor roll 2i, the rotation speed of which is adjustable in dependence upon the rotation speed of the brush.

From the motor I4 a further chain drive 22 ieads to an intermediate wheel 23 which is mounted on a shaft with a wheel forming a component of a chain drive 24. The drive 24 is conducted to a quantity-regulating roll 25 with which, in cooperation with a small counterroll 25a excessive adhesive is scraped from the material M to be flocked after passing through an adhesive reservoir 25. In the reservoir 26 a weight 27 is arranged which holds down the filaments or yarns passing through the adhesive. The material to be flocked, which in the arrangement as illustrated is supplied in a wide band of filaments or yarns consisting for example of 60 parallei threads, is drawn from a winding frame (not shown). The threads conducted parallel by appropriate guide devices run over the guide rolls 28, 29 and 39 to the adhesive reservoir.

In FIG. 2, which shows the apparatus according to the invention in front view, it can be seen how the threads of material M to be flocked, arranged side-by-side in large number, issue side-by-side at the exit side through the opening from the flocking chamber formed beneath the hood 4. it is aiso seen from FIG. 2 that the electrodes 3 arranged beneath the conveyor belt 8 are secured at the closest possible distance beneath the belt. The electrodes can consist of bars lying transversely of the direction of movement of the belt or wires 3 stretched in the same direction. The leading of the electric conductors to the upper and lower electrodes is of very siznpie design in the form of embodiment of the apparatus according to the invention as illustrated. As already stated further above,

' the lower electrode is divided into two sections. The bars or wires in the individual sections are electrically connected with one another; there is however no connection between the two sections. The distance A between the neighbouring bars or wires of the sections 2 and 3 is so selected that no flashover takes place with the applied potentials and under the climatic conditions prevailing in the working space, especially at the airhumidity maintained there. It has appeared that for example at potentials of -30 KV to 60 RV an interval of at least mm. between the neighbouring electrode bars or \vires pertaining to the different sections 2 and 3 is sufficient.

It can be seen from FIG. 3, which is a plan view of the apparatus according to FIGS I and 2, that the sieve bottom w arranged beneath the brush roll I7 is divided into three trapezoidal sections. In the middle section 31 the sieve openings in the bottom are smaller than in the lateral trapezoidal regions 32. This achieves the object that on the belt running through beneath the sieve bottom I9 a central, somewhat more thinly coated strip of flock material is produced, on both sides of which somewhat more heavily flocked strips are formed. So that the transition between the individual regions of strip form does not take place too coarsely, the neighbouring margins of the sieve bottom sections 31 and 32 extend obliquely of the running direction of the conveyor belt conducted through beneath them.

The manner of operation of the apparatus according to the invention consists in that the flock material delivered from the earthed reservoir I6 with the aid of the rotating brush I? through the sieve bottom I9 is brought with the aid of the conveyor belt ti, consisting of electrically nonconductive material, into the flocking chamber formed beneath the hood 4. So that no residual charge remains on the belt h due to the action of the high potential, earthing rolls or earthed scrapers are arranged at suitable points along the belt, which ensure that the belt is free from charge at least in the loading region beneath the reservoir I6.

The flock material lying on the conveyor belt 8, which as mentioned has been applied somewhat more abundantly in the marginal regions than in the middle, firstly comes into the sphere of influence of the activating electrode 2. The activating electrode 2, which regarded in the direction of travel of the belt 8 occupies only a half to a third of the length of the subsequent main electrode 3, is charged to a higher potential than the main electrode 3.

Due to the electrostatic field formed between the activating electrode 2 and the electrode 5, which is connected to high potential of opposite polarity, the flock arriving with the belt is whirled-up. n adjustment of the potentials a uniform, dense cloud forms beneath the hood 4, which cloud however leaves,

the flocking chamber situated beneath the hood neither at the opening 40 nor at the opening 417 The flocking material situated in the cloud is accelerated by the main electrode 3, which is at a somewhat lower negative potential than the activating electrode 2, and is directed onto the adhesive-coated material M-in cooperation with the complementary electrode 5.

The material M is earthed in this case. Earthing becomes possible due to the fact that the adhesive coating renders a certain current conduction possible, which is sufficient for the necessary purpose. 7

With the aid of the apparatus according to the invention success is achieved in producing extraordinarily high grade flocked yarn material in long'term operation without troubles and with high output.

in the production of flocked yarn in long-term operation the activating electrode consisted of five wires tensioned transversely of the direction of movement of the belt, to which accord ing to the climatic conditions of the working room and the flock material to be processed there was applied a high potential of from 33 to -60 KV. The main electrode consisted in the same installation .of 11 wires which were connected to a potential of between 30 and 40 KV. As the complementary electrode a brass plate polished to high gloss was used, which was kept under constant vibration. A potential of between+40 and +45 KV was applied to the complementary electrode.

To avoid residual potential in the conveyor belt 8, the rolls 9, 10 and 13 were earthed. In the processing of 1 mm. nylon flock and 3 denier the middle sieve part 31 of the bottom of the reservoir (FIG. 3) consisted of a sieve of mesh width No. 16, while the two outer sieve parts 32 consisted of sieves of No. 13.

lclaim:

1. Apparatus for electrostatic flocking of textile material including filaments and yarns, said apparatus comprising:

a. a main high tension electrode and a complementary high tension electrode of opposite polarity which are spaced apart to enable an adhesive-coated textile material to be conducted therebetween;

b. an activating high-tension electrode having the same polarity as said main electrode but charged to a greater potential and disposed adjacent to but not in contact with said first electrode;

c. an endless belt for supplying flock material and arranged to travel between said complementary electrode and said main and activating electrodes and in the direction from said activating electrode to said main electrode; and

d. means for conducting said adhesive-coated textile material between said belt and said complementary electrode.

2. Apparatus according to claim 1 wherein the main and activating electrodes each comprise a series of mutually parallel elongate rodlike members which are arranged transversely to the direction of travel of the adhesive-coated material and wherein the complementary electrode comprises a continuous metal plate.

3. Apparatus according to claim 2 wherein the main elec trode comprises approximately twice as many rcdlike members as the activating electrode.

4. Apparatus according to claim 1 wherein the main and activa'ting electrodes are negatively charged and the complementary electrode is positively charged.

5. Apparatus according to claim 4 wherein the activating electrode is charged to a potential of from about 32 to 60 KV, the main electrode is charged to a potential of about 40 KV and the complementary electrode to a potential of from about +30 to 45 KV.

6. Apparatus according to claim 1 wherein the complementary electrode is mounted on a vibrator device.

7. Apparatus according to claim 1 wherein the endless belt is made at least partly from glass fibre and earthing means are provided which are arranged to be contacted by the belt prior to entry and after passage between the electrodes.

8. Apparatus according to claim 1 wherein the endless belt is arranged to travel in sliding contact with said main and activating electrodes.

9. Apparatus according to claim 1 wherein means are provided for depositing flock material onto the endless belt, at a station upstream of said electrodes, said means comprising a rotatable brush which is arranged to brush flock material through a sieve forming the base of a hopper for the flock material, said sieve having openings in the portion disposed above the centre portion of the belt which are smaller than the openings disposed above the outer portion of the belt.

10. Apparatus according to claim 9 wherein the sieve forming the base of the hopper comprises three sieves which are joined together along lines which extend obliquely to the direction of travel of the endless belt.

11. Apparatus according to claim 1 wherein means are provided for coating said textile material with adhesive at a station upstream of said electrodes.

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