JPS6034612A - Cleaning of sintered metallic filter for flow straightening - Google Patents

Abstract

PURPOSE:To remove the clogging material from a sintered metallic filter, to achieve the moderate cooling of the spun filaments in spinning process, and to prevent the mutual welding of the filaments, by immersing a sintered metallic filter in an alkaline solution, neutralizing with an acid solution, and cleaning with steam. CONSTITUTION:In the melt-spinning of polyester fiber, a sintered metallic filter is used to straighten the flow of gas for cooling the filaments extruded from the spinneret. The filter is immersed in an alkaline solution (preferably 0.05-0.5N caustic soda solution) usually at room temperature -80 deg.C for 0.5-5hr. The filter is then immersed in a solution of an acid such as sulfuric acid, hydrochloric acid, etc. (preferably 0.05-0.5N concentration) preferably for 1-60sec to neutralize the attached alkali. The treated filter is washed with water and cleaned with steam.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cleaning a sintered metal filter for rectification.

Hot air or cooling air is often used to heat or cool fibers in the fiber manufacturing process.

For example, in melt spinning synthetic fibers, the yarn spun from a nozzle is cooled by cooling air (so-called quenching air).
It is cooled through a cooling tube that comes out of the pipe, but the cooling air at this time has little string vibration.

In addition, in order to perform proper cooling, it is important to have a uniform wind speed distribution in the circumferential direction of the cooling cylinder and to rectify the flow so that it does not fluctuate over time.

For this reason, such cooling cylinders usually incorporate wire mesh, nonwoven fabric, perforated cylinders, or sintered metal filters to rectify the cooling air. However, since the sintered metal filter itself has a unique porous structure, it has an excellent rectifying effect, but it also prevents impurities in the cooling air, such as spinning fibers. The sintered metal filter is prone to clogging due to adsorption of oligomers, oil droplets, and dust that are released during the process. Therefore, the sintered metal filter must be cleaned periodically or at any point where an abnormality is observed in the rectification effect. death.

It was necessary to remove the obstruction.

Now, common methods for cleaning sintered metal filters include salt decomposition, pickling, passing pressurized air or water from inside the filter, ultrasonic cleaning, or a combination of these methods. According to salt decomposition, there is no problem with combustible materials such as oligomers as long as they are burned up in the salt bath, but they often remain in the filter in the form of char.On the other hand, pickling originally destroys organic materials such as oligomers. Not suitable for washing and removal. On the other hand, methods using compressed air or water, or ultrasonic cleaning can provide a certain degree of cleaning effect, but since sintered metal filters have a unique porous structure, the above-mentioned physical methods are not satisfactory. The desired cleaning effect could not be obtained. In order to apply a sintered metal filter to a hot air or cooling air rectifying means, an important technical issue is how to effectively clean and regenerate the filter.

As mentioned above, the present invention provides effective cleaning and cleaning for sintered metal filters applied to hot air or cooling air rectification means.
The present invention provides a regenerating means to appropriately cool spun yarn during fiber production, especially during spinning, and to prevent yarns from fusing together and reduce denier unevenness. The structure is as follows.

In a method for cleaning and regenerating a rectifying sintered metal filter installed in a gas supply device, the sintered metal filter is immersed in an alkaline solution, then neutralized with an acid solution, and then steam cleaned. A method for cleaning a sintered metal filter for rectification, characterized by:

Hereinafter, the structure of the present invention will be explained in detail. The present invention provides a method for cleaning a sintered metal filter including alkaline solution treatment,
A series of cleaning steps consisting of neutralization with an acid solution (hereinafter referred to as pickling) and steam cleaning is used to remove everyday objects from the filter.

For example, in polyester melt spinning, a cooling cylinder for cooling the yarn discharged from a spinneret is usually equipped with a sintered metal filter to rectify the cooling air. To wash,
First, it is important to immerse the filter in an alkaline solution. This is because in the aforementioned sintered gold layer filter, polyester oligomers and polyester-based dust are the main substances clogging the f-port, so the clogging substances must be dissolved or removed from the pores in the filter by treatment with an alkaline solution in advance. This is because keeping the material in a clean state, combined with the processing effects of subsequent pickling and steam cleaning, provides a significant cleaning effect.

The alkaline solution here may be caustic soda, caustic potash, etc., 0.01-5N, preferably 0.05-0.
Used in the 5N alkaline range. At this time, if the alkali concentration is less than 001N, the solubility of the plugging material is low, and if it exceeds 5N, the substrate of the sintered metal filter (usually bronze) will be attacked by the cleaning process, which requires two times.

In addition, a sintered metal filter is attached to the alkaline solution.
-1 2 1- IJ Yama-no μ + Hole 1 To 71 ng +; lj4 songs are preferably performed in the prone position, and the liquid temperature at that time may be appropriately selected within the range of room temperature to 80°C.

Next, the sintered metal filter is subjected to pickling after the alkaline solution treatment, and the acids used here include sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, and oxalic acid. In this pickling, the filter is immersed in an acid aqueous solution while it is left standing or stirred, thereby neutralizing the alkali content that has adhered during the alkaline solution treatment, and at the same time neutralizing the acid-soluble components in the plugging material. Since this is a process to dissolve ingredients, the acid concentration is 0.
．． 01 to 5 N, preferably 0.05 to 05 N. The immersion time is preferably 1 to 1 zo seconds, preferably 1 to 60 seconds. At this time, if the acid concentration and the immersion time are less than 0.01N and 1 second, the effect of neutralizing alkaline content and the effect of dissolving and removing acid-soluble components of the mouth plug will be small, and if it exceeds 5N and 120 seconds, the alkaline solution treatment will be insufficient. As in the case, the substrate itself of the sintered metal filter becomes attacked.

The sintered metal filter before pickling may be washed with water if necessary, but it is desirable that the filter after pickling be washed with water to remove the cape.

When the pickling is completed, the sintered metal filter is carefully blown with steam of 0.5 to 100 kg/♂ from the if+ inside. So-called steam cleaning is carried out, whereby the clogging components in the filter can be almost completely removed.

After that, pressurized air (usually 0.5 to 6 kg/
cm") may be used to remove and dry the water in the filter.

As described above, the present invention treats the plugs in the sintered metal filter for rectification with an alkaline solution.

This method attempts to clean and regenerate filters through a series of cleaning processes consisting of pickling and steam cleaning, and as this process can almost completely remove the blockages in the filter,
For example, when applied to a sintered metal filter for rectifying the cooling cylinder in polyester melt spinning, the rectifying function of the filter is always maintained properly, the spun yarn discharged from the spinneret is cooled uniformly, and yarn wobbling is prevented. few. As a result, the fusion between yarns and denier unevenness are greatly reduced, and in addition, the drawability of the yarn is improved, which is an excellent effect.

The present invention will be specifically explained below with reference to Examples.

Examples 1 to 4 Polyethylene terephthalate was spun using a normal melt spinning device (die: 250 m jl, number of holes: 2800) at a discharge rate of 1800 g/min and a take-up speed of 1350 m/min, and the yarn was 3.7 times It was drawn to obtain a drawn yarn of 1.5 denier. The cooling cylinder used in this melt spinning apparatus is a cylindrical cooling cylinder as shown in Fig. 1, and in order to provide a uniform wind velocity distribution in the circumferential direction, a 5° nonwoven fabric filter 6 (70μ (cut), wire mesh (50 mesh)7. Each item is new and has been installed.

During the spinning period, the number of spinning days and the yarn fluctuation of the spun yarn.

Fusion, fineness variation rate, and roller wrapping during the stretching process.

The relationship between U/Y and U/Y was investigated and shown in Table 1.

The fusion was achieved by inserting a wire into the running yarn and measuring the number of times the wire moved due to fusion.

Further, the fineness variation rate is a value measured with a deniroscope.

Table 1 After 60 days from the start of spinning, the sintered metal filter was removed from the cooling tube, and the filter was cleaned using the cleaning method of the present invention, and then attached to the original cooling tube and a spinning test was continued. In this case, the cleaning conditions for the sintered metal filter and the spinning and
Stretchability is shown in Table 2.

Margin below As these results show, by applying the cleaning method of the present invention, the plugs in the sintered metal filter for rectification used in polyester melt spinning are almost completely removed.
The rectifying effect of the filter was able to be restored to the same level as when it was first used (new).

Therefore, if the cleaning and regeneration timing of the filter is appropriately selected, it is possible to prevent yarn wobbling during spinning, fusion, wrapping of the drawing roller during drawing, and
It can be seen that /Y can be greatly improved.

Comparative Example 1 The filters of Examples 1 to 4 after 60 days of spinning were decomposed with salt and then pickled with a 0.1 N sulfuric acid aqueous solution to give a weight of 2.0 kg/
It was steam blown with cm2 of steam and washed. The filter was assembled into a cooling cylinder and spinning was carried out in the same manner as in Examples 1 to 4, but the yarn was fused 2.4 times/min and the fineness fluctuation rate was 8.2%.

The stretching roller winding is 0.46 times/l and U/Y is also 13
The number of yarns was 1/10°, and a satisfactory spinning state could not be obtained.

[Brief explanation of the drawing]

l2 cap 2; Base holder 3: Part of the spin block 4: Cooling cylinder 5: Non-woven fabric 6: Sintered metal filter 7: Wire mesh Patent applicant: Toshi Co., Ltd. Top view 1

Claims (2)

[Claims] (1) In a method for cleaning and regenerating a sintered metal filter for rectification installed in a gas supply device, the sintered metal filter is immersed in an alkaline solution, then neutralized with an acid solution, and then dried. A method for cleaning a sintered metal filter for rectification, characterized by performing steam cleaning. (2) The method for cleaning a sintered metal filter for rectification according to claim (1), wherein the gas supply device is a cooling cylinder for cooling the yarn discharged from a spinneret in polyester melt spinning.