JPH1149823A - Continuous suspension polymerization of vinyl chloride-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous suspension polymerization method of a vinyl chloride-based polymer capable of suppressing coarsening of particles and internal high packing of the resultant vinyl chloride-based polymer. SOLUTION: This continuous suspension polymerization method of vinyl chloride-based polymer comprises carrying out suspension polymerization of vinyl chloride monomer alone or a vinyl chloride-based monomer comprising a mixture of the vinyl chloride monomer with a monomer copolymerizable with the vinyl chloride monomer in an aqueous medium containing a dispersing agent while continuously feeding the monomer to a polymerizer together with the dispersing agent, a polymerization initiator and water. In this case, suspension polymerization is carried out while feeding a water-soluble compound containing one or more nitrogen atoms in an amount of 30-500 ppm to the vinyl chloride based monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a continuous suspension polymerization method for a vinyl chloride polymer.

[0002]

2. Description of the Related Art In the production of vinyl chloride polymers, usually, a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith (hereinafter referred to as "vinyl chloride monomer"). Vinyl chloride-based monomer)) and water, dispersant,
A batch type aqueous suspension polymerization method in which a polymerization initiator and the like are charged and the reaction is performed while controlling the reaction temperature to be constant and removing heat is employed.

[0003] As for such an aqueous suspension polymerization method, a continuous suspension polymerization method in which a raw material suspension such as a vinyl chloride monomer, water and a dispersant is continuously supplied in order to enhance productivity is used. Proposed. However, in the case of a vinyl chloride-based monomer, the continuous suspension polymerization method has problems such as a coarse particle phenomenon in which the particle diameter of the produced polymer particles becomes large and a phenomenon of high internal filling in which voids in the polymer particles are eliminated. Yes, it has not been put to practical use.

Regarding the control of the polymer particle structure in the continuous suspension polymerization method, see, for example, JP-A-57-192402.
JP, JP-A-57-205402, JP-A-58-205402
JP-91701, JP-B-6-102682,
JP-B-6-102683, JP-B-6-10268
Various proposals have been made in Japanese Patent Publication No. 5 and Japanese Patent Publication No. 6-102687. However, any of these techniques is effective in controlling the structure of polymer particles such as styrene, but has no effect when polymerizing a vinyl chloride monomer, resulting in coarsening of polymer particles. Also, it was not possible to prevent the generation of so-called glass ball particles.

Some proposals have been made to control the structure of the polymer particles by preventing aggregation of the polymer particles in the initial stage of polymerization, which is called sticky state, in which the resin has high adhesiveness. For example, JP-A-56-1
Japanese Patent Publication No. 18407 discloses a method of lowering the viscosity of polymer particles by setting a higher polymerization temperature in the first polymerization tank among a plurality of polymerization tanks.
In Japanese Patent Application Laid-Open No. 1-18 / 1989, a method of providing a plurality of polymerization tanks passing through a sticky state state in parallel is disclosed.
Japanese Patent Publication No. 081 proposes a method of increasing the agitation of a polymerization tank having a sticky state among a plurality of polymerization tanks. However, there are problems such as the necessity of a complicated operation and the reduction of the volumetric efficiency of the polymerization tank.

In the batch suspension polymerization method, many techniques for adding a water-soluble polymerization inhibitor during polymerization have been known for a long time. Examples of such a polymerization inhibitor include, for example,
JP-A-63-83101 exemplifies hydroxyl-containing compounds such as diethylhydroxylamine or hindered phenols represented by BHT, and nitrites such as sodium nitrite. JP-A-3-275704
In the publication, compounds selected from nitrites such as sodium nitrite, thiocyanates such as ammonium thiocyanate, and water-soluble sulfur-containing organic compounds such as thioethanolamine are preferable, and further, sodium nitrite and ammonium nitrite And thiocyanates such as ammonium thiocyanate and zinc thiocyanate, and water-soluble sulfur-containing organic compounds such as mercaptoethanol.

In addition to these, Japanese Patent Application Laid-Open No. 50-72984
JP, JP-A-50-126786, JP-A-50-126786
-4288, JP-A-53-128986,
JP-A-53-109589, JP-A-1-2974
No. 04 (above, examples of nitrites), JP-A-51-7
6379, JP-A-51-135991, JP-A-52-13591, JP-A-52-18786
Japanese Patent Application Laid-Open (JP-A) No. 52-5882, Japanese Patent Application Laid-Open No. 52-12291, and Japanese Patent Application Laid-Open No. 56-59808 (hereinafter, thiocyanate-based compounds) Examples), JP-A-52-18785, JP-A-53-113879, JP-A-53-280, JP-A-56-98207, JP-A-1-297
No. 405 (the above are examples of sulfur-containing compounds such as thiophosphates), JP-A-56-72003, JP-A-3-2
No. 23307 (the above is an example of a mercapto compound)
Many have been proposed. However, the addition of these substances during polymerization is intended to prevent scale, and in continuous suspension polymerization of a vinyl chloride polymer,
The control of the resulting polymer particle structure could not be achieved.

[0008]

DISCLOSURE OF THE INVENTION In view of the above, the present invention provides a method for continuous suspension polymerization of a vinyl chloride polymer which can suppress coarsening and high internal filling of the resulting vinyl chloride polymer. The purpose is to provide.

[0009]

According to the present invention, a vinyl chloride monomer comprising a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith is dispersed. A continuous suspension polymerization method for a vinyl chloride polymer, wherein suspension polymerization is carried out in an aqueous medium containing a dispersant while continuously supplying the polymerization agent, a polymerization initiator and water to a polymerization vessel. The polymerization is carried out by adding a water-soluble compound containing at least one nitrogen atom to the vinyl chloride monomer by 3
This is a continuous suspension polymerization method for a vinyl chloride polymer which is carried out while supplying 0 to 500 ppm. Hereinafter, the present invention will be described in detail.

The continuous suspension polymerization method for a vinyl chloride polymer according to the present invention is characterized in that the raw material suspension is continuously supplied to a single polymerization vessel or a polymerization vessel in which a plurality of polymerization vessels are connected, and at the same time, a vinyl chloride polymer as a product is produced. The coalescence is continuously discharged.

In the present invention, a vinyl chloride monomer,
Suspension polymerization is performed in an aqueous medium containing a dispersant while continuously supplying a raw material suspension comprising a dispersant, a polymerization initiator and water to a polymerization vessel.

The vinyl chloride monomer comprises a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and a monomer copolymerizable therewith. The monomer copolymerizable with the vinyl chloride monomer is not particularly limited, for example,
Vinyl esters such as vinyl acetate and vinyl propionate;
(Meth) acrylic esters such as methyl (meth) acrylate and ethyl (meth) acrylate; olefins such as ethylene and propylene; copolymerizable with maleic anhydride, acrylonitrile, styrene, vinylidene chloride, and other vinyl chloride monomers Monomers and the like. These may be used alone or in combination of two or more.

The dispersant is not particularly restricted but includes those used in the usual suspension polymerization of vinyl chloride polymers, such as partially saponified polyvinyl alcohol, polyethylene oxide, acrylic acid and gelatin. Water-soluble polymers such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose and hydroxypropylmethylcellulose; water-soluble emulsifiers such as sorbitan monolaurate and polyoxyethylene sorbitan monolaurate. These may be used alone or in combination of two or more.

The polymerization initiator is not particularly limited.
Oil-soluble initiators and the like used in suspension polymerization of ordinary vinyl chloride-based polymers, and the like, for example, di-2-ethylhexylperoxydicarbonate, diethoxyethylperoxydicarbonate, α-cumylperoxy Neodecanate, t-butylperoxyneodecanate, t-
Butyl peroxypivalate, t-butyl peroxy-
Examples include 3,5,5-trimethylhexanoate, acetylcyclohexylsulfonyl peroxide, 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate, lauroyl peroxide and the like. These may be used alone or in combination of two or more.

It is preferable that the polymerization initiator is previously mixed so as to be contained in the vinyl chloride monomer oil droplets in the raw material suspension continuously supplied to the polymerization vessel. The amount of the polymerization initiator to be used is preferably 0.001 to 2% by weight based on the vinyl chloride monomer.

In the present invention, the above suspension polymerization is carried out while supplying a water-soluble compound containing one or more nitrogen atoms. The water-soluble compound is not particularly limited as a compound containing one or more nitrogen atoms, and examples thereof include ammonium salts, amides, amino group-containing substances,
Examples include amines, urea group-containing substances, and nitrogen-containing substances. These may be used alone or in combination of two or more.

Examples of the above ammonium salts include hydroxylammonium chloride, hydroxylammonium sulfate, ammonium chloride, ammonium bromide, ammonium hydrogensulfide, ammonium sulfate, ammonium hydrogensulfate, ammonium thiosulfate, ammonium peroxodisulfate, ammonium amidosulfate, and selenite. Ammonium, ammonium azide, ammonium phosphinate, ammonium phosphonate, ammonium hydrogen phosphonate, ammonium phosphate trihydrate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium cyanate, ammonium carbonate monohydrate, Diammonium bicarbonate carbamate, ammonium metaborate hydrate,
Examples thereof include sodium ammonium hydrogen phosphate tetrahydrate, ammonium formate, ammonium acetate, ammonium oxalate monohydrate, ammonium hydrogen oxalate monohydrate, ammonium tetrafluoroborate, and ammonium carbamate.

Examples of the amides include nitroylamide, m-acetamidophenol, butylamide, hexamethylphosphoric triamide, formamide oxime and the like.

Examples of the above-mentioned amino group-containing substance include:
Aminoguanidine, 4-amino-1,2,4-triazole, 3-aminobutyric acid, 4-aminobutyric acid, p-aminobenzyl alcohol, 2-aminopentanoic acid, 2-amino-2-methyl-1-propanol, DL -2-aminobutyric acid and the like.

Examples of the amines include isopentylamine, N-nitrodimethylamine, 3-pyridylamine, 1,4-butanediamine, 1,3-propanediamine, propylamine, 1,5-pentanediamine,
And pentylamine.

Examples of the urea group-containing substance include acetylthiourea, N-acetyl-N'-methylurea,
-Ethylurea, N, N'-diethylurea, N, N'-dimethylurea, N, N-dimethylurea, N-methylthiourea and the like.

Examples of the nitrogen-containing substance include nitrosyl fluorosulfate, azetidine, 1-acetylcarbazide, antipyrine, 2-imidazoline, imidazole, ethylhydrazide, 6-quinolinol, guanidine carbonate, glycosiamidine, glutaronitrile , Trimethyl cyanurate, succinamic acid, piperazine, pilocarpine, pyrrolidine, hordenine, 1-methylimidazole, 4-methylpiperidine, morpholine, lycopozine, lupinin and the like.

The above water-soluble compound containing one or more nitrogen atoms may be mixed with the raw material suspension in advance and then supplied to a polymerization vessel. The feed to the polymerization vessel may be carried out using a line different from the line for feeding into the vessel. When the raw material suspension is previously mixed with the raw material suspension and then supplied into the polymerization reactor, each raw material may be supplied to a static mixer or the like through a separate line, mixed, and then supplied into the polymerization reactor. After mixing in a pressure-resistant container in advance, the mixture may be supplied to a polymerization vessel. The static mixer is not particularly limited, and for example, a mixer commercially available from Toray Engineering Co., Ltd., Noritake Company, or the like can be used.

The present invention relates to the above-mentioned raw material suspension and the above-mentioned water-soluble compound, which contains one or more nitrogen atoms.
Suspension polymerization is carried out while continuously feeding into the polymerization vessel.The continuous feeding into these polymerization vessels is based on the vinyl chloride in the raw material suspension initially charged in the polymerization vessel. It is preferable to start when the polymerization rate of the system monomer reaches a predetermined value. In this case, when the water-soluble compound containing one or more nitrogen atoms is supplied into the polymerization vessel using a line different from the line for supplying the raw material suspension. Then, the supply of the water-soluble compound containing at least one nitrogen atom into the polymerization vessel is started simultaneously with the supply of the raw material suspension into the polymerization vessel. The supply of the raw material suspension and the water-soluble compound containing one or more nitrogen atoms is preferably performed to a liquid phase portion of a polymerization vessel.

The supply amount of the water-soluble compound containing one or more nitrogen atoms is 30 to 500 ppm based on the vinyl chloride monomer. If it is less than 30 ppm, the effect of inhibiting polymerization at the particle interface and in the aqueous phase bulk is small, and the effect of preventing the particle diameter from increasing is not sufficient.
If it exceeds 0 ppm, the effect of suppressing polymerization is sufficient, but the stability of the oil droplets in an aqueous medium is reduced, and the particle size of the obtained vinyl chloride polymer is increased. Preferably, it is 100 to 400 ppm.

In the continuous suspension polymerization method for a vinyl chloride polymer according to the present invention, the polymerization regulator, chain transfer agent, polymerization inhibitor, Adjusters, stabilizers, scale inhibitors and the like may be used.

The greatest point in performing a continuous suspension polymerization reaction of a vinyl chloride polymer is to suppress the particle size of particles existing in the polymerization vessel for a long time from increasing. When the particle diameter is enlarged, the vinyl chloride polymer finally obtained becomes coarse particles and the inside is highly packed. This enlargement of the particle diameter occurs because monomer oil droplets diffuse into existing particles and polymerize there, and fine particles generated in the aqueous phase bulk adhere to the existing particles. For this reason, in order to suppress the enlargement of the particle diameter, it is important to prevent polymerization at the particle interface and generation of fine particles in the aqueous phase bulk. The effect of the water-soluble compound used in the present invention, which is a compound containing one or more nitrogen atoms, is not necessarily clear, but shows a favorable interaction with a dispersant present at the particle interface, It is speculated that the polymerization is effectively suppressed. For this reason, the obtained vinyl chloride polymer is of excellent quality in which both coarse particle formation and high internal filling are suppressed.
In addition, the effect of preventing scale due to polymerization suppression on the wall of the polymerization vessel is maintained without impairing the operation of the prior art.

[0028]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 In a stainless steel polymerization vessel equipped with a jacket having a capacity of 200 liters and a stirring blade, 90 kg of ion-exchanged water and 525 g of partially saponified polyvinyl alcohol having a saponification degree of 72 mol% were placed.
, The inside of the polymerization vessel was evacuated to 100 mmHg, and 75 kg of vinyl chloride monomer was charged. After pressurizing 60 g of cumyl peroxyneodecane as a polymerization initiator, the temperature was raised to 57 ° C.

At the same time when the temperature reached 57 ° C., continuous supply of the raw material suspension was started, and simultaneously, continuous supply of a 5% aqueous solution of ammonium amidosulfate was started from another line. Then, withdrawal of the slurry was started so as to keep the internal volume constant, and a continuous polymerization reaction was performed.

The raw material suspension at this time is prepared by adding a 3% aqueous solution of partially saponified polyvinyl alcohol having a saponification degree of 72 mol%, cumyl peroxyneodecanate, and ion-exchanged water to a vinyl chloride monomer in a pipe. And a static mixer. At this time, the supply rate was 25 kg / h for a vinyl chloride monomer, 5831 g / h for a 3% aqueous solution of partially saponified polyvinyl alcohol having a saponification degree of 72 mol%, 20 g / h for cumyl peroxyneodecanate, and ion-exchanged water. Was 29.2 kg / h. The amount of ammonium amidosulfate was 290 ppm based on the vinyl chloride monomer.

After the continuous polymerization reaction for 30 hours, the supply of the raw material suspension and the aqueous solution of ammonium amidosulfate was stopped, and the exhaust gas was cooled to stop the continuous polymerization reaction, and the contents were taken out. This was dehydrated and dried to obtain a vinyl chloride polymer, and the particle size distribution, bulk specific gravity, porosity, and gel time were evaluated by the following methods. The results are shown in Table 2.

Evaluation method (1) Particle size distribution Measured according to JIS K8801. (2) Bulk specific gravity Measured according to JIS K6721.

(3) Porosity Using a mercury intrusion porosimeter, 2000 kg / cm
^The porosity was determined by measuring the volume of mercury injected at 100 g per 100 g of the vinyl chloride polymer at ² G.

(4) Gelation time The following resin composition was prepared by adding a stabilizer and the like to the vinyl chloride polymer, and 65 g of this resin composition was charged into a plastograph (Rheocord 90) manufactured by Haake Co., Ltd. ° C, 50
The time until gelation was measured at rpm.・ 100 parts by weight of vinyl chloride polymer ・ 2 parts by weight of dibutyltin mercapto (JF-10B, manufactured by Sankyokisei Co., Ltd.) ・ 0.5 parts by weight of ester wax (Wax-op, manufactured by Hoechst)

Example 2 Instead of a 5% aqueous solution of ammonium amidosulfate, a 5% aqueous solution of formamide oxime was used, and the feed rate was 200 g.
A vinyl chloride-based polymer was obtained and evaluated in the same manner as in Example 1 except that / h was used. The results are shown in Table 2. At this time, the amount of formamide oxime was 400 ppm based on the vinyl chloride monomer.

Example 3 A vinyl chloride polymer was obtained and evaluated in the same manner as in Example 1, except that N-methylhydroxylamine was used in place of ammonium amidosulfate and the feed rate was 35 g / h. The results are shown in Table 2. At this time, the amount of N-methylhydroxylamine was 70 ppm with respect to the vinyl chloride monomer.

Comparative Examples 1-3 A vinyl chloride polymer was obtained and evaluated in the same manner as in Example 1 except that the conditions shown in Table 1 were used. The results are shown in Table 2.

[0039]

[Table 1]

Comparative Example 4 A vinyl chloride polymer was obtained in the same manner as in Example 1 except that the polymerization was carried out batchwise without continuously adding the raw materials.
evaluated. The results are shown in Table 2. In addition, as compared with Examples 1 to 3, polymerization took time and labor, and the productivity was poor.

[0041]

[Table 2]

[0042]

According to the continuous suspension polymerization method for a vinyl chloride polymer of the present invention, which has the above-mentioned structure, a vinyl chloride polymer having suppressed coarse particles and high internal filling can be obtained. . In addition, the obtained vinyl chloride polymer has excellent particle size distribution and gelation performance, and a product of the same quality as the vinyl chloride polymer obtained by the batch suspension polymerization method is used in batch suspension. It can be obtained with higher productivity than the turbid polymerization method.

Claims (1)

[Claims] 1. A vinyl chloride monomer comprising a vinyl chloride monomer alone or a mixture of a vinyl chloride monomer and a copolymerizable monomer, together with a dispersant, a polymerization initiator and water. A continuous suspension polymerization method for a vinyl chloride-based polymer in which suspension polymerization is carried out in an aqueous medium containing a dispersant while continuously supplying to a polymerization vessel, wherein the suspension polymerization is a water-soluble compound. Wherein the compound containing at least one nitrogen atom is supplied while supplying 30 to 500 ppm to the vinyl chloride monomer.