JPS6049010A - Vapor-phase polymerization of vinyl chloride - Google Patents

Abstract

PURPOSE:To obtain the titled high-quality polymer efficiently by polymerizing a vinyl chloride monomer, etc. in the presence of an initiator having high activity consisting of a diisopropyl peroxycarbonate and di-2-ethoxyethyl peroxycarbonate under a specific condition. CONSTITUTION:In vapor-phase polymerization of a vinyl chloride monomer or a monomer copolymerizable with it and the vinyl chloride monomer, when the polymerization is carried out at 55-65 deg.C polymerization temperature at a pressure in a ratio Pr of polymerization pressure/saturated vapor pressure of 1>Pr> 0.5, diisopropyl peroxycarbonate and di-2-ethoxyethyl peroxycarbonate in a weight ratio of >=1/1 are used to give the desired polymer.

Description

Detailed Description of the Invention The present invention provides an improved polymer with high reactivity in the gas phase polymerization of vinyl chloride monomer (hereinafter abbreviated as VCM) or a comonomer that can copolymerize it. It's about legality.

Regarding gas phase polymerization of VCM, Japanese Patent Publication No. 14666/1973
, Special Publication No. 52-44918. U.S. Patent 3,578,64
It is known that polymerization using a radical initiator such as No. 6 is possible.

Gas phase polymerization is carried out at an operating pressure Po lower than the saturated vapor pressure Ps of the VCM at the polymerization temperature. That is, relative pressure Pr=P
When o/Ps, 1>Pr>0.5 is approximately the polymerization range. In general, polymerization in the gas phase is compared to polymerization in the liquid phase.
Although it is often thought that the reactivity is low, it is actually surprisingly fast. The reason for this is (1) the seed polymer prepared by bulk prepolymerization has high porosity, which varies depending on the polymerization temperature and Pr, but the amount of VCM adsorbed by the seed polymer is unexpectedly large;
It ranges from 20 to 65 wt% (dry weight basis) and is involved in the reaction.

(2) In liquid phase batch reaction, the initially charged VCM decreases as the polymerization progresses, and in the latter half the amount of VCM to be reacted gradually decreases, whereas in gas phase polymerization, the reaction pressure is kept constant; Adsorption and polymerization are replenishing consumption. That is, as the amount of powder increases through polymerization, the total amount of VCM present at the reaction site increases.

(3) Compared to liquid phase reaction, gas phase polymerization has no continuous phase, so termination reactions are less likely to occur, and therefore the apparent growth reaction becomes larger.

(4) In a liquid phase reaction, an initiator is added at the beginning and the polymerization reaction is carried out, and the initiator is not usually added during the reaction. The reaction usually proceeds in an S-shaped curve. That is,
At the start, the reaction is slow, then in the middle it becomes straight, accelerates further, and finally becomes gentle before coming to a stop. That is, the reaction rate for each hour draws a mountain-shaped curve. However, recent efforts have been made to combine it with low-temperature active initiators to create a relatively gentle plateau shape.

On the other hand, in gas phase polymerization, when the VCM in the system polymerizes and turns into a polymer, the pressure decreases, so a fixed ratio of VCM gas is adsorbed by the polymer formed at the same time as it is supplied, so the amount of reaction per hour is clear. When the reaction rate slows down, the initiator can be added.

Therefore, it is ideally possible to maintain a linear reaction rate.

For the above reasons, the reactivity of gas phase polymerization is faster than expected, even in the gas phase.

Examples of typical initiators used in gas phase polymerization are shown in the table below. These initiators are appropriately selected depending on the polymerization temperature.

One of the features of gas phase polymerization is that the reactivity is greatly influenced by Pr.

As Pr becomes higher, the reactivity becomes significantly higher, the bulk specific gravity also becomes larger, the particle size distribution becomes more chassisy, and the production rate of coarse particles decreases. In addition, the initial coloring (hue) and thermal stability of the product during processing are also improved.

However, polymerization inside the particles progresses, porosity decreases, and fish-eye characteristics (hereinafter abbreviated as FE characteristics) also deteriorate.

Therefore, as mentioned above, gas phase polymerization occurs when 0.5<Pr<1, but F. E. In order to keep the characteristics at a good level and bring other characteristics within the practical level, Pr should be 0.65 or more.
Pr is preferably in a range of less than 85, preferably from 0.70 to 0.80. For example, P (average degree of polymerization.

same as below. )≒Pr0.75 at a polymerization temperature of 10OO
PVC produced per hour per gram of pure organic peroxide at
(Polyvinyl chloride. The same applies hereinafter) is 350 to 450 g
With PVC/gIhr, P≒1000 is obtained by suspension polymerization method. Reactivity at polymerization temperature is 250-350gPVC/g
■Exceeding hr. However, in the case of gas phase polymerization, since a slightly higher space capacity is required, the productivity per volume of the reaction vessel is the same or slightly lower.

In order to overcome this productivity problem, the inventors conducted intensive research and completed the present invention by discovering that when a specific initiator is used in a complex form, the reactivity becomes significantly higher due to a mutual effect. did.

That is, at a polymerization temperature of 55 to 65°C, IPP and E
It has been found that when EP is used at a polymerization ratio of 1/1 or more, the reactivity is equal to or higher than that of the highest PP.

These events will be explained.

For example, when performing gas phase polymerization at 60.5° C. Pr0.75, the reactivity depending on the type of initiator is as follows. (The mixing ratio is a weight ratio, and the unit of reactivity is gPVC/gIh.
It is r. same as below. ) In single initiator systems, the reactivity is ND.
<EEP<MC<IPP, but in a composite system, M
When C is combined with ND, EEP, and AIBN, the reactivity is lower than that of the single system. Although a mutual effect is observed in the MC/IPP system, it does not exceed the reactivity of IPP.

In the case of EEP as well, the reactivity with ND and MC is lower than that of the individual. Approximately 12 for EEP/IPP (1/3) only
5% reactivity.

What should be further noted is that when we investigated the change in reactivity by changing Pr, we found the results shown in the following table.

The results are shown in FIG. As is clear from these, P
The dependence of the reactivity on r differs depending on the combination of initiator types, and the combination of EEP/IPP (1/3) significantly improves the reactivity due to the mutual effect.

The effects of these types of initiators and their combinations show similar trends in the temperature range of 55-65°C.

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

Example 1, Comparative Examples 1 to 6 (1) Preparation of seed polymer In a 100 liter stainless steel polymerization can with an anchor-type stirrer, 0.2 g/m2 of Evans blue/0.19 g of sodium lauryl sulfate was added in advance.
A scale inhibitor was applied at a ratio of 2g/m2/polyvinyl alcohol/m2 and dried at 50°C. Ethyl cellulose T-503.0g, stearic acid 3.0g, higher alcohol (Kao Soap Co., Ltd. Calcol 68) 1.0g,
Dioctyltin dilaurate (Nitto Kasei JVS+810
5) Add 3.0g of VCM, deaerate, add 56kg of VCM, stir at 180rpm, and pour warm water into the jacket to remove the air.
℃ and initiator isobutyryl peroxide (I
B) 25.0 ml of 25% isoparaffin solution and 24.4 trimethyl-pentyl-2-peroxyphenooxyacetate (TMP-PA) 30% isoparaffin solution 10.
Wash 0 ml into the can with 4 kg of VCM to start polymerization.

Cooling water is passed through the jacket to maintain a constant internal temperature.

Ethyl cellulose T pre-dissolved in VCM for 1.5 hours
-100.50gr was charged with 2kg of VCM, mixed for 5 minutes, and then recovered under constant pressure at an internal temperature of 50°C and an internal pressure of 7.2kg/cm2G. The jacket temperature was 54℃ for the first 60 minutes, and then 52℃.
℃ and slightly slow down the collection rate. At an internal temperature of 52℃, the pressure is recovered, and then the provider (manufactured by Fujikin) is used to recover the residual V under reduced pressure.
Remove the CM and take out the polymer. Polymerization rate 17.1%,
It was 1.8% on a 48 mesh sieve.

(2) Equipped with a gas phase polymerization rising blade length of 350m/m complex blade and a chisaku blade in the middle plate.
A 100L polymerization can made of stainless steel, with an inlet of 1.0mm at the top of the can.
Install a circulating flow type VCM spray nozzle with an outlet of 1.5 mmφ.

Apply the above-mentioned scale inhibitor in advance and let it dry.

Add 3.8 kg of the seed polymer from (1), stir at 80 rpm, deaerate, heat water through the jacket, and gradually add VCM through the nozzle to raise the temperature.

Internal temperature 60.5℃ Internal pressure 7.5kg/cm2G (PrO.7
5), add initiator EEP 50% toluene solution/IP
Spray 2.7 ml of P50% toluene solution (1/3) from a nozzle using a VCM pressure pump.

Polymerization begins. The jacket is maintained at a constant temperature of 61° C. (to prevent scale formation). Polymerization heat is removed by adjusting the stroke of the VCM pressure pump at the internal temperature. On the other hand, the internal pressure is adjusted, and excess evaporated VCM gas is recovered, cooled, liquefied, and recycled. The amount of reaction can be determined from the weight loss in the measuring tank over time. When the reaction rate slows down, add the initiator as described above. Inhibitor 4.4'-Blycylidenebis(3-methyl-6-tert-butylphenol) 3.5 at growth ratio 5.5 times
gr and 1.5 g of todiphenylmonodecyl phosphite dissolved in VCM in advance are sprayed, collected and recovered under reduced pressure, and after removing residual VCM, the product is taken out.

The results are shown in the table below.

Results for other initiator combinations are also shown in the table below.

[Brief explanation of drawings]

FIG. 1 is a graph showing the Pr dependence of the reactivity of various initiators. Patent Applicant: Toyo Fukai Koukin Co., Ltd. LJ, /LJ0750.800.85 (Fig. 1 Φ < Sn, 1lll6n, 5°C 1" 1.5) □1 / ), 900,951.00

Claims (1)

[Claims] (1) In gas phase polymerization of vinyl chloride monomer or a monomer copolymerizable therewith with vinyl chloride monomer, polymerization temperature 5
When carrying out the polymerization at a temperature of 5° C. or higher and lower than 65° C., the ratio Pr of polymerization pressure/saturated vapor pressure at polymerization temperature is 1>Pr) 0.5, diisopropyl peroxycarbonate and di-2 - A polymerization method characterized by using a mixture of ethoxyethyl peroxycarbonate at a weight ratio of 1/1 or more.