JPH07214002A - Fine particle removing method for vinyl chloride resin granule for paste working - Google Patents

Abstract

PURPOSE:To provide a method capable of efficiently removing a fine particle contained in a granule of a vinyl chloride resin for paste working being a raw material for processed goods such as a wall paper or a floor material without breaking the granule. CONSTITUTION:The fine particle 2 contained in the granule 1 is removed accompanied with upward stream of air 4 while the granule 1 moves to one end of a dispersing plate 15 having many air holes 14 while supplying the granule of the vinyl chloride resin for paste working containing 0.1-0.5wt.% moisture from the other end of the dispersing plate 15 while upwardly supplying the air 4 from the below of the dispersing plate 15 and fluidizing the granule 1 on the dispersing plated 15 by the upward stream of the air 4 jetting from the air holes. Then, since the flow of upward stream of the air 4 forming a fluidized bed has only small shearing force, the granule 1 hasn't possibility of breaking. And the excellent fluidized bed is formed and the fine particle 2 is efficiently classified since the moisture in the granule 1 is limitted to 0.1-0.5wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing fine particles from a vinyl chloride resin granule for paste processing, which is a raw material for processed products such as wallpaper and flooring.

[0002]

2. Description of the Related Art Conventionally, a vinyl chloride resin for paste processing is dispersed in a plasticizer at room temperature to form a plastisol, and the plastisol is heated and gelated through steps such as coating to process wallpaper, flooring, etc. I have a product. By the way, if there are coarse particles in the processed product, the product value is lost. Therefore, the vinyl chloride resin for paste processing needs to be dispersed rapidly in the plastisol without becoming coarse particles. Therefore, the vinyl chloride resin for paste processing has been crushed to have an average particle size of about 0.1 to 10 μm, but the crushed resin has deteriorated powder characteristics and dusts to deteriorate the working environment. There are drawbacks such as making automatic metering difficult.

Therefore, recently, attempts have been made to granulate a processing vinyl chloride resin and use the granulated product as it is without crushing it. For example, Japanese Patent Application Laid-Open No. 2-225529 proposes a method of obtaining an agglomerate by spray-drying an aqueous dispersion of a vinyl chloride resin for paste processing at a relatively low temperature with a spray dryer. This granulated product is granulated to have an average particle size of 30 μm or more, and its strength is set to be relatively weak so that it can be easily dispersed in the plasticizer.

[0004]

However, even in the recent attempts as described above, since the generation of fine particles is inevitable during granulation, it is necessary to remove the fine particles to prevent the deterioration of the powder characteristics. However, none of the conventional methods for removing fine particles is satisfactory. For example, when an air stream classifier typified by a general cyclone or the like is used, the granules are set to have low strength, so that there is a problem that they are crushed by the shearing force of the air stream. Further, when a classifying device that utilizes the difference in sedimentation velocity of particles such as a fluidized bed is used, the shearing force of the air flow is small, so there is no risk of crushing the granules, but there is the problem of poor classification efficiency. The present invention improves on the conventional method for removing fine particles,
The purpose is to eliminate such problems.

[0005]

In order to achieve the above object, the method of removing fine particles of a vinyl chloride resin granule for paste processing of the present invention is designed so that air is blown upward from below a dispersion plate having a large number of ventilation holes. While being supplied, a granulation body of a vinyl chloride resin for paste processing containing 0.1 to 0.5% by weight of water is supplied from one end of the dispersion plate, and the upward air ejected from the ventilation holes causes the granules on the dispersion plate. The granules are fluidized and fine particles contained in the granules are removed by being entrained in the upward air while the granules move to the other end of the dispersion plate. The amount of the granulated material fluidized on the dispersion plate is preferably 15 kg or less per 1 m ² of the surface area of the dispersion plate.

[0006]

In the method of removing fine particles having the above-mentioned structure, among particles contained in the granulated body fluidized on the dispersion plate, fine particles having a terminal velocity smaller than the superficial velocity of upward air are converted into upward air. Accompanied and rises from the dispersion plate. On the other hand, the coarse particles having a terminal velocity higher than the superficial velocity remain on the dispersion plate and move to the other end of the dispersion plate. Thus, the granules are classified into fine particles and coarse particles at the boundary of the upward superficial velocity of air.

In the above classification, the water content of the granules during supply is limited to 0.1 to 0.5% by weight in order to form a good fluidized bed on the dispersion plate. That is, the water content is 0.1
If it is less than wt%, the granules will be charged and aggregated due to friction between particles in the fluidized bed and the classification efficiency of fine particles will be deteriorated. If the water content exceeds 0.5 wt%, the granules will be separated from each other due to moisture. The efficiency of classification of fine particles deteriorates due to aggregation.

Further, the amount of the granulated material fluidized on the dispersion plate is limited to 15 kg or less per 1 m ² of surface area of the dispersion plate in order to prevent deterioration of fine particle classification efficiency. That is, if the amount of granules exceeds 15 kg / m ² , the classification efficiency of fine particles deteriorates. The reason is not always clear,
This is probably because the fluidized bed becomes thicker and it becomes difficult to disperse the fine particles in the deep part.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An example of an apparatus for carrying out the present invention will be described below with reference to FIG. As shown in FIG. 1, in the method for removing fine particles of this embodiment, a granulated body 1 of a vinyl chloride resin for paste processing is classified into fine particles 2 and coarse particles 3 by a fluidized bed type classifier to remove fine particles 2. With coarse particles 3
Is collected as a product. As the granulated body 1,
Obtained by spray drying an aqueous dispersion of a vinyl chloride resin for paste processing with a solid content concentration of 50% obtained by polymerization at a dry air temperature of 90 ° C and a haiku temperature of 48 ° C with a spray dryer equipped with a rotary disk type atomizer. The average particle size is 80 μm, the angle of repose is 36.5 degrees, and the bulk specific gravity is 0.512 g / cc.
The granular material of is used.

The classification of the granulated body 1 is carried out in the following manner. First, the air 4 is supplied to the bottom of the container 13 through the humidifier 12 by the blower blower 11. Inside the container 13, a rectangular dispersion plate having a large number of ventilation holes 14 (width 15 in this example) is provided.
cm x length 85 cm) 15 is attached. The air hole 14 has a hole diameter that allows the air 4 to substantially pass therethrough but does not allow the granulated body 1 to pass therethrough (0.4 mm in this example). The air 4 supplied to the bottom of the container 15 is the dispersion plate 1
5 is blown out through the ventilation hole 14 from below, and the air volume control valve 16
An upward airflow is generated with a superficial velocity V (m / s) corresponding to the opening degree of. At the same time, the suction blower 17 allows the container 15
The internal air 4 is exhausted through a dust collector 18 including a cyclone and a bag filter. At that time, the air flow control valve 19 is operated to balance the pressure in the fluidized bed.

Next, the granules 1 stored in the hopper 20 are supplied to one end of the dispersion plate 15 with a constant supply amount Fo (Kg / hr) according to the opening degree of the measuring rotary valve 21. The granules 1 on the dispersion plate 15 are fluidized when the superficial velocity V of the air 4 reaches a constant value, and move toward the other end of the dispersion plate 15. During the movement of the granulated body 1, among the particles contained in the granulated body 1, the fine particles 2 having a terminal velocity smaller than the superficial velocity V rise together with the upward air 4, and the dust collector 18 Captured in. On the other hand, the terminal velocity is the superficial velocity V
The larger coarse particles 3 remain on the dispersion plate 15 and continue to move, and are discharged from the other end of the dispersion plate 15 to the recovery duct 22 with a discharge amount F (Kg / hr) and are recovered as a product.

In this embodiment, when the discharge amount F of the coarse particles 3 becomes steady, the supply of the granules 1 and the air 4 is stopped at the same time, and the granules 1 remaining on the dispersion plate 15 are recovered. Then, the weight (Kg) is measured, and this weight is divided by the surface area (m ² ) of the dispersion plate 15 to obtain the fluidized granules 1 on the dispersion plate 15 per 1 m ² of the surface area of the dispersion plate 15. The amount W (Kg / m ² ) accumulated on the surface was calculated. Further, the discharge amount F of the coarse particles 3 is divided by the supply amount Fo of the granules 1 and multiplied by 100, and the value is defined as the product recovery rate R (%).

Further, the particle size distribution of the coarse particles 3 after classification is measured by a Coulter counter, and the partial classification efficiency βi is calculated from this particle size distribution and the particle size distribution of the granulated body 1 before classification. The classification efficiency E was defined as βi. Here, the partial classification efficiency βi refers to a group of particles having a particle size distributed within a specified range as a specified particle, the weight G of the specified particle included in the coarse particles 3 after classification, and the production before classification. The ratio with the weight Go of the designated particles contained in the particle 1.
Therefore, Becomes

The classification efficiency E indicates that when the designated particles are the fine particles 2 having a certain particle diameter or less, when E = 1, the fine particles 2 are scattered and completely removed from the fluidized bed at the time of classification. When E = 0, it means that nothing was removed.
On the contrary, when the designated particle is the coarse particle 3 having a certain size or more, it indicates that the coarse particle 3 is scattered from the fluidized bed at the time of classification and is not recovered at all when E = 1. E
When = 0, it means that all of them are collected. In this embodiment,
The classification efficiency E was calculated for the fine particles 2 having a particle diameter of 32 μm or less and the coarse particles 3 having a particle diameter of 64 μm or more.

Examples 1 to 6 and Comparative Examples 1 and 2 The results of classification carried out in Examples 1 to 6 and Comparative Examples 1 and 2 will be described in more detail below in Table 1.

[0016]

[Table 1]

In Examples 1, 2, and 3, the superficial velocity V of the air 4 is 0.1 m / s, 0.2 m / s, and 0.3 m / s, respectively.
s, and granules 1 having a water content H of 0.22% by weight were supplied at a supply amount Fo = 150 kg / hr. Two minutes after the start of the supply of the granulated body 1, the coarse particles 3 constantly came out from the recovery duct 22. It can be seen from the classification efficiency E of the fine particles 2 that the amount of the fine particles 2 to be removed can be adjusted by adjusting the superficial velocity V.

In Examples 4, 5 and 6, the feed amount Fo of the granulated body 1 was 50 kg / hr, 200 kg / hr and 300 kg / hr, respectively.
Classification was carried out according to Example 2 except that the time was adjusted to hr. As can be seen from the product recovery rate R and the classification efficiency E of the fine particles 2,
In Example 6, since the deposition amount W exceeds the limit value of 15 kg / m ² , the fine particles 2 are slightly left in the product although the product is recovered well.

In Comparative Examples 1 and 2, classification was carried out according to Example 2 except that the water content H of the granules 1 at the time of supply was adjusted to 0.08% by weight and 0.60% by weight, respectively. Product recovery rate R
From the classification efficiency E of the fine particles 2 and the moisture H, the water content H is within the limited range of 0.
It can be seen that when the amount deviates from 1 to 0.5% by weight, a large amount of the fine particles 2 remains in the product although the product is recovered well.

[0020]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the paste-processing vinyl chloride resin granules, which are supplied onto the dispersion plate having a large number of vent holes, are supplied from above the dispersion plate by the air supplied upward. Since the particles are fluidized and the fine particles in the granules are entrained in the upward air flow to be removed, the shearing force of the air flow is small and there is no risk of the granules being crushed by the air flow. Moreover, the water content of the granulated product during supply is 0.1 to 0.1%.
Since it is limited to the range of 0.5% by weight, a fluidized bed of good granules is formed on the dispersion plate. Therefore, it is excellent in the classification efficiency of fine particles. In addition, when the amount of the fluidized granules on the dispersion plate is set to 15 kg or less per 1 m ² of the surface area of the dispersion plate,
The amount of granulated material supplied is optimized, and more efficient classification is possible.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fluidized bed type classification device for carrying out the method of the present invention.

[Explanation of symbols]

 1 Granule 2 Fine Particles 3 Coarse Particles 4 Air 14 Vents 15 Dispersion Plate

Claims (2)

[Claims] 1. While supplying air upward from below a dispersion plate having a large number of ventilation holes, it is possible to adjust the air flow from one end of the dispersion plate to 0.
The granules of a vinyl chloride resin for paste processing containing 1 to 0.5% by weight of water are supplied, and the granules on the dispersion plate are fluidized by the upward air ejected from the ventilation holes, and the granules are fluidized. A method for removing fine particles of a vinyl chloride resin granule for paste processing, wherein the fine particles contained in the granule are removed by being entrained in the upward air while moving to the other end of the dispersion plate. 2. The method for removing fine particles of a vinyl chloride resin granule for paste processing according to claim 1, wherein the amount of the granulated body fluidized on the dispersion plate is 15 kg or less per 1 m ² of the surface area of the dispersion plate.