JPH04337330A - Production of vinyl chloride resin for paste - Google Patents

Abstract

PURPOSE:To produce a vinyl chloride resin for paste having excellent powder characteristics such as dusting, molding and fluidity and satisfying sol properties required in processing. CONSTITUTION:A vinyl chloride resin for paste is fed between two drums wherein interior of at least one of the drums is being sucked by a vacuum pump, a resin layer formed on the surface of the drum by deaeration and pressurizing is raked out by a scraper, the prepared platy vinyl chloride resin is pushed against a wire net, passed through the meshes thereof and granulated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride resin for paste. Specifically, the present invention relates to a method for producing a vinyl chloride resin for paste, which has excellent powder properties such as fluidity and dust-emitting properties, and satisfies the sol properties required for paste processing.

0002

2. Description of the Related Art Vinyl chloride resin for paste is usually used in the form of a paste sol, which is prepared by mixing and dispersing a plasticizer together with a heat stabilizer, filler, and other compounding agents. If coarse particles are present in this sol, there are problems such as sedimentation and scratches on the surface during processing, so when PVC resin for paste is mixed with plasticizer etc., it quickly disperses and becomes uniform. It is important to become

For this reason, vinyl chloride resin for paste is usually obtained by emulsion polymerization or microsuspension polymerization of vinyl chloride or a monomer mixture mainly composed of vinyl chloride in the presence of an emulsifier, and the particle size is approximately 0.05～
It is a spray-dried aqueous dispersion of a resin having a diameter of 10 μm, and is partially agglomerated to provide a fine powder with a particle size of about 100 μm or less.

0004

[Problems to be Solved by the Invention] However, since ordinary vinyl chloride resin for paste is a fine powder, it not only causes a deterioration of the working environment due to scattering of the powder, but also has poor fluidity, so it cannot be used in packaging bags. Problems occur during filling or unloading, and automatic weighing and automatic transportation are difficult. In order to improve the powder properties, it is necessary to increase the particle size of the resin to make particles that are hard to break and have a high density, but this makes it difficult to satisfy the sol physical properties required during processing.

In order to solve these problems, an organic liquid and a vinyl chloride resin having a large particle size are added and mixed to an aqueous dispersion of a vinyl chloride resin for paste, and the vinyl chloride resin is separated as a granular aggregate and then dried. Method (Unexamined Japanese Patent Publication No. 5
9-109504), a method of adding a liquid binder to vinyl chloride resin for paste and stirring and granulating it (Japanese Patent Application Laid-Open No. 1983-1999)
Although various methods such as No. 210634) have been proposed, none of them are necessarily satisfactory, such as complicated operations or insufficient powder properties or sol properties.

As a result of intensive study on a vinyl chloride resin for paste that is easy to operate and satisfies both powder properties and sol physical properties, the present inventor has developed a plate-like resin obtained by deaerating and pressurizing fine vinyl chloride resin powder for paste. The present inventors have discovered that a resin obtained by sizing the resin satisfies both powder properties and sol physical properties, and has completed the present invention.

[0007]

[Means for Solving the Problem] That is, at least one of two opposing drums is a filter drum whose inside is sucked by a vacuum pump, and both drums rotate in a direction to sandwich the supplied resin. PVC resin for paste is supplied as a raw material between the drums, and the resin layer formed on the drum surface is scraped off with a scraper after being deaerated and pressurized between the drums, and the resulting plate-shaped PVC resin is sized. This is a method for producing vinyl chloride resin for paste.

The powdered vinyl chloride resin for paste used as a raw material in the present invention is generally used as a vinyl chloride resin for paste, and is made by mixing vinyl chloride or a monomer mixture mainly composed of vinyl chloride in the presence of an emulsifier. It is spray-dried from an aqueous dispersion of resin with a particle size of about 10 μm or less obtained by emulsion polymerization or microsuspension polymerization, and is usually partially agglomerated to form a fine powder with a particle size of about 100 μm or less. It is.

[0009] The two opposing drums are both rotated in a direction to sandwich the supplied resin, and a raw material, a powdered vinyl chloride resin for paste, is supplied from above between the drums. At least one of the drums is a filter drum, the interior of which is suctioned with a vacuum pump. It is common for only one of the drums to be a filter drum. The vinyl chloride resin is sucked from inside the drum on the surface of the filter drum and degassed, and at the same time is pressurized by the rotating drum to form a resin layer on the surface of the rotating drum. When this is continuously scraped off with a scraper, a plate-shaped resin is discharged from the bottom of the drum. Next, this plate-shaped resin is sized to obtain the intended vinyl chloride resin for paste.

[0010] Normally, the rotation speed of the drum is about 3 to 20 rpm.
The drum gap is about 3 to 15 mm, and the vacuum pressure inside the drum is about 50 to 200 Torr. The raw material resin is supplied by falling naturally from a hopper at the top of the drum in an amount necessary to meet these conditions. Although there are no particular limitations on the method for sizing the particles, it is usually carried out by pressing the particles against a wire mesh with an opening of about 2 to 10 mm and passing the particles through the mesh. The particle size of the resulting resin depends on the opening of the wire mesh used, but usually a granular resin is obtained in which particles with a particle size of 150 μm or more account for 80% or more, and particles with a particle size of 250 μm or more account for 60% or more. This resin can be used as is for paste processing, but is sieved if necessary.

The bulk specific gravity of this resin varies depending on the bulk specific gravity of the raw material resin and the resin degassing and pressurizing conditions, and the bulk specific gravity is about 0.50.
If it exceeds ~0.55 g/cc, it becomes difficult to satisfy the sol physical properties. Therefore, the bulk specific gravity of deaeration and pressurization is approximately 0.50 to 0.
Not exceeding 55g/cc, preferably 0.50g/cc
The following conditions are appropriately selected from within the range of the above conditions.

[0012] The bulk specific gravity increases by reducing the number of rotations of the drum, reducing the gap between the drums, and increasing the degree of vacuum within the drum. As an example, the drum internal pressure is 50
Torr, when the drum gap is 5 to 6 mm or less and the drum rotation speed is 3 to 6 rpm, the bulk specific gravity is often 0.5 g/cc or more, and when the drum gap is 8 mm or more, the bulk specific gravity is almost constant regardless of the drum rotation speed. A resin of 0.5 g/cc or less is obtained.

The vinyl chloride resin for paste obtained by the method of the present invention becomes a granular resin having a larger bulk specific gravity and larger particle size than the raw material resin, and has good powder properties such as fluidity. Although the fine particles of the resin are densely attached and the particle size is large, the degree of adhesion is weaker than that of granular resin obtained by other granulation methods, and the sol property is good because it crumbles easily when converted into a sol. It is thought that this is the case.

[0014]

According to the present invention, a vinyl chloride resin for paste can be obtained which has excellent powder properties such as dust generation and fluidity, and which satisfies the sol properties required during processing.

[0015]

[Example] Example 1 A filter drum whose inside is suctioned by a vacuum pump and a pressure drum facing each other are rotated in the direction to sandwich the supplied resin, and a raw material of PVC resin for paste is supplied between the drums. Deaeration and pressurization were performed. Both drums used had an outer diameter of 160 mmφ and a length of 220 mmL.
As the vinyl chloride resin for the paste, Sumilit (trademark) Px-NLT manufactured by Sumitomo Chemical Industries was used. After deaerating and pressurizing, the resin layer formed on the surface of the rotating drum was continuously scraped off with a scraper, and the plate-shaped resin was discharged from below the drum. Next, this plate-shaped resin was pressed against a wire mesh with an opening of 3.5 mm, and the particles were sized by passing through the mesh to obtain a powdered vinyl chloride resin for paste. The operating conditions and results are shown in Table 1.

[0016] The bulk specific gravity of the raw material was 0.23 g/cc.

The bulk specific gravity was measured by the method described in JIS K 6721. The NF value is one index expressing the physical properties of the sol. 60 parts of di-2-ethylhexyl phthalate (DOP), which is a plasticizer, is added to 100 parts of the resin, and the resulting sol is rated according to JIS K 5701 or ASTM.
It was measured using a grindmeter according to the method described in D 1210-64. This indicates that the sol is preferably 70 μm or less. In all of the obtained resins, particles having a particle size of 150 μm or more accounted for 80% or more, and particles with a particle size of 250 μm or more accounted for 60% or more.

Example 2 PVC resin for paste, Sumilit Px-NLT and Sumilit Px-Q were prepared in the same manner as in Example 1.
The LT (all manufactured by Sumitomo Chemical Industries) was subjected to deaeration and pressurization and sieving. The obtained resins all have a particle size of 1
More than 80% of the particles were 50 μm or more, and more than 60% of the particles were 250 μm or more. The particle size distribution in the sol of this resin and the raw resin (prepared in the same manner as in the measurement of the NF value in Example 1) was measured using a laser beam diffraction particle sizer.

The degassing and pressurizing conditions used are shown below. The results are shown in Table 2. The particle size distributions in the sol of the raw material and the product are almost the same, indicating that the granular resin obtained by sizing after deaerating and pressurizing is easily collapsed during solization, and the particle size distribution is almost the same as before.

[0020]

Example 3 A blocking test was conducted on Smilit Px-QLT. A cylinder with a diameter of 51 mm is placed on a thin plate made of vinyl chloride, and 100 cc of the measurement sample is placed inside the cylinder and packed lightly. A thin vinyl chloride plate was placed on top of it as a drop lid, a load of 2 kg was applied thereto, and the container was left at room temperature for a predetermined period of time. Thereafter, a block-shaped resin was extruded from the cylinder. Next, put a load on the block you took out,
The load at which the block collapses was determined. The results are shown in Table 3. The product was obtained by deaeration and pressurization at a drum rotation speed of 3.3 rpm, a drum gap of 6 mm, and a drum internal pressure of 75 Torr, and then grading.

[0022] Both the degree of compression and the crushing load are reduced, indicating that the resin is less likely to clump.

Example 4 PVC resin for paste, Sumilit Px-QLH and Sumilit Px-Q were prepared in the same manner as in Example 1.
The LT (all manufactured by Sumitomo Chemical Industries) was subjected to deaeration and pressurization and sieving. The powder properties of the obtained resin and its raw material resin were measured using a powder tester (manufactured by Hosokawa Micron). The results are shown in Table 4.

The degassing and pressurizing conditions used are shown below. ┌────────────┬─────
───┬────────┐ │ Deaeration and pressurization conditions │ Px-QLH │
Px-QLT │ ├───────
──────┼────────┼────────┤
│Drum rotation speed (rpm) │ 3
．． 3 │ 3.3 │
│Drum gap (mm) │
5 │ 6
│ │Drum internal pressure (Torr)│
270 │ 75
│ └────────────┴────
──────┴────────┘

[0025]
Table 4 ┌────────
─┬──────────┬──────────┐
│ │ Px
-QLH │ Px-QLT │
│ ├────
┬────┼────┬────┤ │
│ Raw materials │ Products │ Raw materials │ Products │ ├
────────┼────┼────┼────┼─
───┤ │ Liquidity index │
30 │ 42 │ 28 │ 45
│ ├────────┼────┼────
─┼────┼────┤ │ Jet property index │ 48 │ 43 │ 53
│ ４３ │ └────────┴
────┴────┴────┴────┘The larger the value of the fluidity index, the better the fluidity, and the lower the flowability index, the less the flowability. . (“Powder physical property measurement method” edited by Sohachiro Hayakawa, Asakura Shoten)

002
6] Comparative Example 1 Sumilit Px-NLT, a vinyl chloride resin for paste, was granulated using a tumbling fluidized dryer that sprays a binder while stirring, granulates the mixture, and then dries it. As binders, DOP and water were used at 15 wt% and 10 wt%, respectively, based on the raw material vinyl chloride resin. The obtained resin contains 90% or more particles with a particle size of 150 μm or more, and 25
The particle size of 0 μm or more was 80% or more, the bulk specific gravity was 0.41 g/cc, and although the fluidity and dust generation properties were good, the NF value was 160 μm, which did not satisfy the sol physical properties.

Claims (3)

[Claims] Claim 1: At least one of two opposing drums is a filter drum whose interior is suctioned by a vacuum pump, and a material for pasting the raw material is placed between the drums, which both rotate in a direction to sandwich the supplied resin. Vinyl chloride for paste, characterized by supplying vinyl chloride resin, deaerating and pressurizing it between drums, and scraping off the resin layer formed on the drum surface with a scraper, and sizing the plate-shaped vinyl chloride resin. Method of manufacturing resin. 2. The method for producing a vinyl chloride resin for paste according to claim 1, wherein the rotation speed of the drum is 3 to 20 rpm, the gap between the drums is 3 to 15 mm, and the pressure inside the drum to be evacuated is 50 to 200 Torr. 3. The method for producing a vinyl chloride resin for paste according to claim 1, wherein the plate-shaped vinyl chloride resin is pressed against a wire mesh and sized by passing through the mesh.