JPH0371441B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a suspension polymerization method for vinyl chloride using an improved stirring blade, and more specifically, the stirring blade has significantly improved stirring efficiency by providing an auxiliary blade on the tip blade. This invention relates to a suspension polymerization method for obtaining significantly improved vinyl chloride resins. ``Prior art'' ``Problems to be solved by the invention'' Conventionally, blue margin blades, paddle blades, Faudle blades, propeller blades, turbine blades, etc. have been known as stirring blades, and appropriate ones are used depending on the purpose. Stirring blades of different shapes are selectively used. Among these, the Blue Margin impeller can rotate at high speed without increasing the required stirring power and has a large shearing action, making it a reasonable agitation impeller for the purpose of dispersing droplets. It has been thought that there is a problem with homogeneous stirring within the system. For example, in the suspension polymerization of vinyl chloride monomers, blue margin blades are commonly used along with paddle blades and fordler blades as stirring blades. Fixture eye for vinyl chloride resin (hereinafter abbreviated as PVC),
Market demands for residual monomers have become increasingly strict in recent years, and in particular, the problem of plasticizers with polymeric plasticizers such as polyesters, which have relatively low plasticizing ability and high viscosity, has become a problem. It's starting to be done. In order to solve these problems, it is necessary to increase the dispersion frequency of monomer droplets as much as possible in the particle formation stage at the initial stage of polymerization to prevent the formation of low-porosity particles that occur when the dispersion frequency is low. The key is to increase the homogeneity of particles within the polymerization system. In particular, a reflux condenser is sometimes used in the production of vinyl chloride resins to improve productivity and save energy, but in that case, the polymerization suspension contains gas generated from monomer droplets. ,
There is a problem in that the homogeneity of stirring is reduced and the above-mentioned fish eye in the polymer plasticizer system is worsened. "Means for Solving the Problem" In view of the above circumstances, the inventors of the present invention have conducted intensive research, and have found that the agitation efficiency can be improved by erecting an auxiliary vane on the outer surface of the main wing at the tip of an ordinary blue margin vane. If vinyl chloride is subjected to suspension polymerization using a stirring blade that has been greatly improved, the above-mentioned problems such as the fixation eye can be significantly improved, and in particular, the suspension polymerization method of vinyl chloride resin using a reflux condenser is known. The present invention has been completed based on the discovery that remarkable effects can be achieved in the following. That is, the first aspect of the present invention is characterized in that polymerization is carried out using a stirring blade formed by erecting an auxiliary blade tilted with respect to the horizontal direction of rotation on the outer surface of the main blade at the tip of a normal blue margin blade. The second aspect of the present invention is a suspension polymerization method of vinyl chloride resin, and the second aspect of the present invention is an aileron blade that is inclined with respect to the horizontal direction of rotation and is erected on the outer surface of the main wing at the tip of a normal blue margin wing. A suspension polymerization method for vinyl chloride resin characterized by using a stirring blade and a polymerization reactor equipped with a reflux condenser in the gas phase of the polymerization reactor or outside the polymerization reactor. It is something. The reason why the PVC fixation is significantly improved by using the improved stirring blade in the present invention is that, as mentioned above, the stirring efficiency is improved, and the frequency of dispersion and coalescence of monomer droplets in the initial stage of polymerization is increased. This is thought to be because the homogeneity between particles in the polymerization system increases. The reason why this effect is especially remarkable in suspension polymerization using a reflux condenser is that in addition to the above reasons, the improved stirring blades generate upstream and downstream flow and have a large entrainment effect. It is thought that this is because it has the effect of suppressing the foaming phenomenon peculiar to the use of the polymer, and has the effect of making the polymerization suspension uniform. An explanation will be given based on drawings showing an embodiment of the stirring blade used in the present invention. FIG. 1 is a plan view of the stirring blade, and FIG. 2 is a front view of the main blade. In these figures, a main wing 3 is attached to the tip of a support section 2 extending in the normal direction from the vertical axis 1 (a normal blue margin wing has such a structure). Auxiliary wings 4 having a predetermined inclination are attached to the outer surface of the main wing 3. 13 to 14 are perspective views showing embodiments of the main wing 3 and the auxiliary wing 4. FIG. In the present invention, the ailerons 4 are provided so as to have a predetermined inclination angle α of elevation or inclination with respect to the rotation direction. Although the inclination angle is not particularly limited, a range of approximately 50 to 30 degrees is suitable. If it is less than 5 degrees, the upstream and downstream sides tend to be small and the overall agitation flow effect will be insufficient. On the other hand, if it exceeds 30 degrees, the upstream and downstream areas will become too large, consuming a large amount of stirring power and resulting in an overdispersed state. , may lead to abnormal polymerization. Also, the area of the ailerons 4 is 3 main wings per 1 aileron.
Good results are obtained for 20-60% of the area.
If it is less than 20%, it is too small and the results obtained by attaching the ailerons (shearing effect, stirring effect) will be insufficient, and if it exceeds 60%, a large amount of stirring power will be consumed, resulting in an overdispersed state. May lead to abnormal polymerization. Furthermore, scale tends to adhere, and it takes a lot of effort and time to remove it. Furthermore, the aileron 4 does not necessarily need to be provided perpendicularly to the main wing 3, and may be inclined, for example, within a range of 45 to 135 degrees. The number of ailerons 4 is not particularly limited either, and may be determined as appropriate depending on the size of the main wing 3, etc., but usually one or two aileron wings can provide a suitable result. The shape of the aileron 4 is not particularly limited, and may be any shape having a certain area, such as a rectangular shape, a rhombic shape, or a triangular shape, as shown in the drawing. Further, it is not necessarily necessary to provide the main wing 3 over the entire width thereof, and furthermore, it may be interrupted in the middle. There is no particular limit to the thickness either, and it may be determined as appropriate depending on the size of the main wing 3 and the auxiliary wing 4, etc. When two or more ailerons are provided for one main wing, their shapes and sizes do not necessarily have to be the same, and may be different shapes and sizes. The ailerons 4 may be welded to the main wing 3 to form an integral structure with the main wing, or may be made separately and attached using mechanical means such as bolts. When carrying out suspension polymerization of vinyl chloride monomer or a mixture with other monomers that can be copolymerized with vinyl chloride monomer using the above-mentioned stirring blade, as mentioned above, it has the effect of improving the fish eye, and a reflux condenser is attached. Particularly remarkable effects are exhibited when a polymerization machine is used. Examples of other monomers that can be copolymerized with the vinyl chloride monomer in the present invention include olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl stearate, methyl acrylate, and methyl methacrylate. Acrylic acid esters, esters and anhydrides of acids such as maleic acid or fumaric acid, nitrile compounds such as acrylonitrile, and vinylidene compounds such as vinylidene chloride. The polymerization initiator used in the present invention includes initiators commonly used in vinyl chloride suspension polymerization, such as lauroyl peroxide, 3,5,
5-trimethylhexanoyl peroxide, t
- organic peroxides such as butyl peroxypivalate, t-butylperoxyneodecanoate, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate and acetylcyclohexylsulfonyl peroxide; Examples include one or a mixture of two or more azo compounds such as α,α'-azobisisobutyronitrile and α,α'-azobis2,4-dimethylvaleronitrile. The suspending agent used in the present invention may be a known suspending agent, such as partially saponified polyvinyl alcohol, vinyl acetate-maleic anhydride copolymer, styrene-maleic anhydride copolymer, polyvinylpyrrolidone, gelatin, starch. , methylcellulose, hydroxypropylcellulose, etc. In the present invention, a molecular weight regulator can also be used if necessary. Further, the initiator, suspending agent, molecular weight regulator, etc. used in the polymerization reaction may be added to the polymerization reaction system all at once at the beginning, or may be added in portions during the polymerization reaction. The polymerization reaction temperature range in the present invention is usually 40 to 75
°C, but is not particularly limited. "Examples" and "Comparative Examples" The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited in any way by these. Examples 1 to 3, Comparative Example 1 1200 g of 2-ethylhexyl alcohol and 0.84 g of partially saponified polyvinyl alcohol were dissolved in a 5-glass reactor with an inner diameter of 140 mm each equipped with three stages of the three types of stirring blades shown in Table 1. After charging 2,400 g of water and stirring at 550 rpm for 60 minutes, the suspension in the reactor was taken out into a 10% by weight aqueous solution of partially saponified polyvinyl alcohol using a dropper, shaken lightly to stabilize the suspended particles, and then examined with an optical microscope. The particle size was measured using Next, 300 g of 2-ethylhexyl alcohol in which 1.8 g of blue dye (product name: Diamond Resin Blue-P, manufactured by Mitsubishi Kasei Corporation) was dissolved was added, and after addition,
At the 15th, 30th, and 60th minutes, the suspension in the reactor was taken out into a 10% by weight aqueous solution of partially saponified polyvinyl alcohol using a dropper, and the number ratio of colored particles was examined using an optical microscope. . On the other hand, for comparison, a similar experiment was conducted on a normal blue margin blade, and Comparative Example 1 was obtained.
The results are shown in Table 1. Table 1 shows that, compared to ordinary blue margin blades, the blades of the present invention all have smaller average particle diameters of suspended particles, and the ratio of colored particles increases in a short time, indicating higher stirring efficiency. .

[Table] Examples 4, 5, Comparative Example 2 Inner diameter with three stages of stirring blades shown in Table 2 installed
Using a 1.0 m x 1.7 m ³ polymerization machine, 140 parts by weight of water in which 0.07 parts by weight of partially saponified polyvinyl alcohol was dissolved was charged, 0.048 parts by weight of initiator di-2-ethylhexyl peroxydicarbonate was added, and the mixture was degassed. Then, 100 parts by weight (550 kg) of vinyl chloride monomer was charged and polymerized at 57°C. When the internal pressure of the can decreased by 1 kg/cm ² , unreacted monomer was recovered to obtain a vinyl chloride resin.
Incidentally, the polymerization conversion rate was 83%. For comparison, a normal blue margin blade was operated in the same manner as Comparative Example 2. The physical properties of the obtained resin were evaluated according to the following method. The results obtained are shown in Table 2. From Table 2, it can be seen that the number of fish eyes is significantly reduced compared to a normal blue margin wing. Physical property evaluation method Bulk specific gravity: According to JIS K-6721. Particle size distribution: Based on sieve shaking method. Porosity: Using a mercury intrusion porosimeter (Model 5-7118) manufactured by AMINCO in the United States, calculate the volume of mercury injected per 100 g of vinyl chloride resin between an absolute pressure of 31 and 1011 psi (pore diameter of 0.17 to 5.8 μm). The porosity was determined by measurement. Fishery Eye: 100 parts by weight of vinyl chloride resin obtained by polymerization, 50 parts by weight of plasticizer (PN250 (adipic acid polyester; molecular weight approximately 2000), manufactured by Adeka Argus), 3 parts by weight of tribase, 0.5 parts by weight of stearic acid. 0.4 parts by weight of titanium dioxide and 0.2 parts by weight of carbon black were mixed, left to stand for more than 3 hours, and then kneaded with an 8-inch roll at 150°C (sheet thickness 0.2 mm) at the 8th minute and 10th minute, respectively. The sheets were cut out and the number of transparent particles in the 5 cm x 5 cm sheet was shown. Examples 6 to 13 A vinyl chloride resin was obtained in the same manner as in Example 4 except that the heave angle α or area of the aileron was changed as shown in Table 2, and the physical properties were evaluated. From the results in Table 2, the elevation angle of the ailerons is 5 to 30.
It can be seen that a degree and area of 20 to 60% of the main wing gives more suitable results. Example 14, Comparative Example 3 Internal diameter 1.0 with a reflux condenser with a heat transfer area of 5 m ²
The stirring blades shown in Table 2 were installed in a 1.7 m ³ polymerization machine.
Step installation, partially saponified polyvinyl alcohol 0.7
140 parts by weight of water in which 1 part by weight was dissolved was charged, 0.048 parts by weight of initiator di-2-ethylhexyl peroxydicarbonate was added, and after degassing, 100 parts by weight (550 kg) of vinyl chloride monomer was charged, and the mixture was heated at 57°C. When the polymerization conversion rate reaches 5%, start passing the cooling water to the reflux condenser.
Heat removal load in the reflux condenser after 30 minutes
Polymerization is continued while adjusting the pressure to 30,000Kcal/Hr, and when the internal pressure drops by 1Kg/ ^cm2 from the steady pressure, the operation of the reflux condenser is stopped, the unreacted monomer is recovered, and the vinyl chloride resin is Obtained. The polymerization conversion rate at this time was 83%. As Comparative Example 3, a normal blue margin blade was operated in the same manner. The evaluation results of the obtained resin are shown in Table 2. Compared to products using normal blue margin blades, there were very few fish eyes, and a reflux condenser was not used and normal blue margin blades were used. It can be seen that the level is equivalent to or higher than that of the resin (Comparative Example 2).

【table】

[Table] ``Action'' ``Effects of the invention'' By installing the aileron blades upright, the dispersion ability and circulation flow are greatly improved compared to ordinary blue margin blades.
When a stirring blade with dramatically improved stirring efficiency is applied to vinyl chloride suspension polymerization, it is possible to significantly reduce fish eyes, and this effect is particularly noticeable in suspension polymerization using a reflux condenser. It is.

[Brief explanation of drawings]

FIG. 1 is a plan view of the stirring blade, FIG. 2 is a front view of the main blade, and FIGS. 3 to 14 are perspective views of essential parts showing embodiments of the present invention. 1...Vertical axis, 2...Support part, 3...Main wing, 4
...Ailerons.

Claims (1)

[Scope of Claims] 1. Chlorination characterized in that polymerization is carried out using a stirring blade formed by erecting an auxiliary blade tilted with respect to the horizontal direction of rotation on the outer surface of the main blade at the tip of an ordinary blue margin blade. Suspension polymerization method for vinyl resin. 2 Using a stirring blade consisting of an auxiliary blade that is inclined with respect to the horizontal direction of rotation on the outer surface of the main blade at the tip of a normal blue margin blade, and refluxing to the gas phase of the polymerization reactor or outside the polymerization reactor. A suspension polymerization method for vinyl chloride resin, which is characterized by polymerization using a polymerization reactor equipped with a condenser.