JPS6047008A - Bulk polymerization of vinyl chloride - Google Patents

Abstract

PURPOSE:To form a vinyl chloride polymer suitable as a seed polymer for vapor phase polymerization, by bulk-polymerizing vinyl chloride in a specified condition. CONSTITUTION:Vinyl chloride (optionally, together with other copolymerizable monomers) is bulk-polymerized to a conversion of 14-25% and unreacted monomers are recovered at constant pressure under a condition including the use of an anchor-type impeller having an impeller diameter corresponding to 93-96% of the inside diameter of the reaction vessel, an impeller speed of 100-300rpm, and a reactor inside temperature of 45-60 deg.C. The system is further evacuated to remove monomers and with draw the vinyl chloride polymer. The obtained vinyl chloride polymer particles have a high bulk density and, when vinyl chloride is polymerized in vapor phase by using them as a seed polymer, a polymer having good fish eye property and a high bulk density can be obtained. It is preferable that the ratio of polymerization pressure to saturated vapor pressure of monomers at the polymerization temperature is about 0.7-0.8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method of vapor phase polymerization of vinyl chloride monomer (hereinafter abbreviated as vCM) or a comonomer copolymerizable mainly with vinyl chloride monomer (vCM), which has high bulk specific gravity and fish-eye characteristics. The present invention relates to a method for producing a seed polymer suitable for obtaining a good quality product.

Regarding gas phase polymerization of VCM, Japanese Patent Publication No. 52-44918
, Japanese Patent Publication No. 4B-14666, US 1ml Patent 3, 578.
646, etc., but the resulting gas-phase polymerized product has poor porosity and lacks uniformity of q1, resulting in poor gelling properties during processing and fish-eye properties (hereinafter referred to as FF).
It is abbreviated as i-characteristic. ) is also a poor, sand-like polymer and has been judged to have little industrial value, despite some significant process advantages.

As a result of intensive research, the inventors found that it has good porosity and F.
We have discovered that it is possible to obtain a gas phase polymerized product with good E% properties, albeit under limited conditions (patent pending).

That is, (a) Bulk polymerization is performed at a polymerization rate of 10% or more and less than 25% to produce a porous powdered seed polymer.

(b) During bulk polymerization, as an initial additive, a polymeric substance such as soluble naethyl cellulose, ethene-vinyl acetate, etc. is added to vCM at 910 to 10.00011 FI per polymer to be contained inside the particles.

(c) Furthermore, a lubricant such as a higher fatty acid or a higher alcohol is added in an amount of 10 to 100% per polymer to prevent particle agglomeration and improve the structure of secondary particles constituting the particles.

2) Metallic soaps of higher fatty acids or θl stabilizers of organotin compounds are added to polymers of 910 to io, oo.

ρ - To add a sword.

(e) Before collecting unreacted V C'M, the polymer substance of (a) is added in an amount of 930 to 10,000 ppm per polymer to coat the particle surface.

However, there is a drawback that the bulk specific gravity of gas-phase polymerized products is lower than that of commercially available turbid polymerized products. As a result of intensive research to improve this point, we decided to limit the conditions for creating the ridge polymer.

A known method for increasing the bulk specific gravity of gas-phase polymerized products is to use finely powdered polyvinyl chloride (
Hereinafter, polyvinyl chloride will be referred to as "Pvc". ) in yuzu, or polymerization in the presence of an organic solvent that is soluble in VCM but not in the generated PVC (U.S. Patent No. 625,952, 1% Showa 58-25310.

5B-98312), but these known methods do not necessarily satisfy the porosity and 18% properties even though the bulk specific gravity is high, and when polymerization is carried out in the presence of an organic solvent, its removal Therefore, the disadvantage is that the gross process becomes complicated.

At a constant polymerization temperature 1. When gas phase polymerization is carried out at a constant polymerization pressure, the bulk specific gravity of the resulting gas phase polymerized product is largely dependent on the bulk specific gravity of the starting seed polymer.

Furthermore, when a certain seed polymer is used and gas phase polymerization is carried out at a certain polymerization temperature, the bulk specific gravity of the product increases as the operating pressure increases by 1. Moreover, when the proliferation ratio is increased, it increases gradually. This relationship is shown in Section 1.21g.

Therefore, it can be seen that when performing gas phase polymerization under certain conditions, increasing the bulk specific gravity of the Maki polymer is an effective means for increasing the bulk specific gravity of the gas phase polymerized product. Therefore,
The present invention was completed by studying various conditions for bulk prepolymerization.

That is, (1) Bulk prepolymerization is carried out under the same conditions, and the bulk specific gravity of the seed polymer becomes higher when the internal temperature of the reactor is higher during constant pressure recovery of the raisin-reacted VCM. However, if this temperature is too high,
Gelled substances are more likely to occur. The temperature is preferably 45-60°C.

(2) The bulk specific gravity of the seed polymer becomes higher when the stirring rotational speed during constant pressure recovery is higher to some extent. If this rotational speed is too high, gelation tends to occur. That is, anchor type stirring s
100, regardless of the equipment size.
~500 rpm is good. The inner diameter of the reactor must be 93% to 96%; if it is less than 93%, stirring will be insufficient, and if it exceeds 96%, the blades will be between the reactor inner wall. This is because there is a possibility that it may bite into the polymer and move.

+31 If the recovery rate of unreacted VCM is increased too much,
Individual particles are partially brought to a low temperature by the heat of evaporation of unreacted VOM, resulting in low-temperature aggregation, which tends to increase the fraction on the sieve and deteriorate the FD characteristics of the seed polymer itself. Therefore, an appropriate recovery rate is required so that each particle formed by polymerization exists independently.

In constant pressure recovery, it is desirable to recover 40 to 50% in the first 50 minutes and 70 to 50% in the first 60 minutes, and thereafter reduce the temperature difference between the jacket and the inside of the reactor to further slow down the recovery rate. .

(4) The polymerization rate of bulk polymerization is also important; if the polymerization rate is less than 10%, the particles themselves generated by polymerization are soft and unreacted VC
The heat and stirring shear during the M recovery process cause agglomeration and coagulation, and although the bulk specific gravity itself becomes high, the porosity decreases and the particle size distribution becomes broad, producing coarse sieve particles. 1
If it is less than 4%, either the bulk, specific gravity or porosity is bad.

Therefore, the polymerization rate in bulk polymerization must be between 14 and 25%, at which the individual particle shapes become clear, especially between 14 and 2.
0% is good, and the seed polymer obtained under the recovery conditions (1) to (2) with a polymerization rate in this range has high porosity inside the particles, and has a rounded shape with few irregularities, so it is bulky. High specific gravity.

Using the seed polymer made under these conditions, Pr (polymerization pressure/
Saturated vapor pressure ratio of monomers at polymerization temperature.

same as below. ) When polymerized under the gas phase polymerization conditions of Q.
A product with good properties and high bulk specific gravity can be obtained.

Referring to the relationship between polymerization operating pressure in gas phase polymerization, Pr
If the value of
characteristics will deteriorate. Therefore, in order to obtain a product with good FE characteristics, it is preferable to lower Pr, but PrO,7
If it is less than this, the reactivity decreases, and the bulk specific gravity, thermal stability, etc. decrease, making it impractical. Therefore, the reactivity is also at a high level.
In order to have good E characteristics and keep bulk specific gravity and thermal stability at appropriate levels, a range of Pra 7 to 0.8 is preferable.

The invention is not limited to homopolymerization of VOM, but also VCM such as 70M and other vinyl halides; olefins such as ethylene; and vinyl esters such as vinyl acetate and vinyl propionate.
It can also be applied to copolymerization with monomers copolymerizable with.

Next, examples of the present invention will be described, but the present invention is not limited only to the examples.

Example 1 Evans blue and polyvinyl alcohol were applied as scale inhibitors to the inner surface of a 1001 stainless steel polymerization can with an anchor-type stirring blade, and after drying, ethyl cellulose T-50 (manufactured by Vercules) 3Lor, stearic acid 3. Or, higher alcohol having 16 to 18 carbon atoms (Calcol 68 manufactured by Kako Soup Co., Ltd.)1. Of, dioctyltin dilaurate (TVSΦ8105 manufactured by Nitto Kasei Co., Ltd.)5. The system was deaerated by vacuum, nitrogen substitution, and vacuum (under 5 Torr 34), and 56 kg of VCM was charged, stirred at 1 B orpm, heated by passing hot water through the jacket, and heated to an internal temperature of 56°C. 25.0 ml of isobutyl peroxide (1B) 25% isoparaffin solution and 2.4.4-trimethyl-pene f
h-2, +-oxyphenooxyacetate) (TMP
-pA) 6o% isoparaffin solution 1 [lLOml] was put into the initiator charger, and after removing the air in the charger, the initiator was washed into the can with V OM'4 kg using a pressure pump,
Polymerization starts. Cooling water is regulated and communicated to the jacket to maintain a constant internal temperature. 0,514 in advance in 1.5 hours
'l Ethyl cellulose N-1005, O in a stirring Isori melting tank
2 was dissolved under pressure with V CM 2 kg,
After mixing for 5 minutes, internal temperature 50℃, internal pressure 7.2 ky/c
Constant pressure recovery at 240 r'pm at m"0. The first 60
54°C hot water is passed through the jacket for a few minutes to quickly collect it.

When carried out in this way, 4 of the unreacted V'CM will be removed in the first 60 minutes.
0-30% and 70-50% recovery in 60 minutes.

Thereafter, the hot water in the jacket was lowered to 52°C, and the collection rate was slightly reduced. When the internal temperature reaches 52°C, autopressure recovery and reduced pressure recovery are performed to remove residual VCM and then the product is taken out. The polymerization rate was 17.5%, and 1.5% on a 48 mesh sieve.

A 1001 stainless steel plate with an anchor-shaped blade and a strip of maple agitator in the middle was coated with the above-mentioned scale inhibitor in advance, and 1. The above-mentioned seed polymer 1.
Pour 8 kg, stir at 80 rpm after degassing, raise the temperature by pouring hot water through the jacket, and make the inlet 1 mm φ and the outlet 1.5 y.
rtiφ, 70M was gradually introduced through the rotating bottle spray nozzle and the pressure was increased to 60.5°C. 7. Okg/cm”G (
When Pr O, 75) is reached, the initiator C-3-methyl-3
- Pour 10 ml of 50% toluene solution of methoxybutyl peroxydicarbonate (MO) into a charger and deair it, then...
Spray from a spray nozzle using a V OM 7JD pressure pump. Polymerization reaction begins.

The jacket was maintained at a constant temperature of 61.0°C, and the heat of polymerization was removed by rolling the flow of the VCM cylinder to keep the internal temperature constant. The 70M gas evaporated by removing the 11'I combined heat is recovered by adjusting the internal pressure to a set pressure. The recovered gas is liquefied in a condenser and recycled. The reaction rate can be determined by the V0M decrease in the measuring tank over time, and when it decreases, the initiator is added. Growth ratio 5.5
Inhibitor 4.4-butylidene bis(3-methyl-6
- tertiary butylphenol) s, 5 y in vCM in advance
The solution dissolved in the bath was dried to recover unreacted VOM, and the residual VCM was removed under reduced pressure to take out a product of 21.0 mm.

On the 48 mesh fWii, it was 1.5%.

The results are shown in Table 1.

Example 2 Treatment 1] Using the same equipment as in 1, lump formation was carried out using the same formulation, and the rotation speed during collection was 180 rpm. Other details are the same as in Example 1, and the results are shown in Table 1.

Example 6 Table 1 shows the results of the same procedure as in Example 1 except that the rotational speed during bulk polymerization was lowered to 120 rpm.

Comparative Example 1 Table 1 shows the results obtained under the same conditions as in Example 1, with a rotational speed of 60 rpm during collection.

Comparative Example 2 Same formulation as Example 1, initiator T, B 25% 21. Oml
, TMP-PA 50% 10 mg was used for polymerization. The rotation speed during recovery was 240 rpm. The results are shown in Table 1.

Comparative Example 3 Polymerization was carried out in the same manner as Comparative Example 2, and the number of revolutions during recovery was 180.
The results are shown in Table 1 in rpm.

Comparative Example 4 Polymerization was carried out in the same manner as Comparative Example 2, and the number of rotations during collection was 12.
Orpm and the results are shown in Table 1.

Examples 4-7. Comparative examples 5 to 7 Next, examples and comparative examples in which Pr is changed will be shown.

Gas phase polymerization was carried out using the same apparatus as in Example 1 and the same seed polymer, but with different Pr. Table 2 shows the results.

Next, the temperature during constant pressure recovery was 50°G and 45°C.

Examples 9 and 9 where the temperature was changed to 35°C. The results of Comparative Example 8 are shown in Table 5.

The jacket temperature at the time of collection was set to +4° C. for the first 60 minutes and +2° C. thereafter, and the speed of collection was fast at the beginning and slow at the end, and the collection was performed at a constant rate.

The equipment and operation were the same as in Example 1.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the bulk specific gravity of the polymer, the proliferation ratio in gas phase polymerization, and the bulk ratio of the gas phase polymerized product (0). It is a graph showing the relationship between bulk specific gravity. Patent applicant: Toyo Soda Kogyo Co., Ltd.

Claims (1)

[Claims] il+ In the homopolymerization or copolymerization method of vinyl chloride by bulk polymerization, (a) polymerization is carried out at a polymerization rate of 14 to 25%, (1))
The unreacted monomers are recovered at (a) a temperature inside the reactor of 45 to 60°C during constant pressure recovery, and (b) a rotational speed of 100 to 300 rpm of an anchor-shaped stirring blade with a pivot diameter of 93 to 96% of the inner diameter of the reactor. A method for bulk polymerization of vinyl chloride, which is characterized in that it is carried out under certain conditions. (2) In constant pressure recovery of unreacted monomer, 40 to 60% during the first 60 minutes, and