JPS58198505A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To obtain a high-quality polymer, by employing ammonia as an alkali component added and carrying out the reaction under conditions of a specified oxygen concentration in a process for producing a vinyl chloride polymer wherein a catalyst is formed in a reaction vessel. CONSTITUTION:A polymerization vessel is charged with water and a suspending agent (e.g., partially saponified polyvinyl alcohol). The polymerization system is then evacuated and purged with nitrogen to lower the oxygen concentration of the system to 100ppm or below, based on the total monomer used. Then, the vessel is charged with (A) vinyl chloride (other copolymerizable monomers may also be used), (B) above about 0.01pt.wt., per 100pts.wt. monomer, alkyl halogenoformate (e.g., methyl chloroformate), (C) about 0.1-5mol, per mol of component B, of an inorganic peroxide (e.g., hydrogen peroxide) and (D) about 0.2- 10mol, per mol of component B, of ammonia, and the reaction mixture is suspension-polymerized at 30-70 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for producing a vinyl chloride polymer while producing a catalyst in a polymerization vessel.

Generally, when vinyl chloride or a mixture of vinyl chloride and a heavy material copolymerizable with it is polymerized, organic peroxides such as dianrubroxide, dialkyl peroxide, peroxy ester, noalkyl peroquine dicarbonate, etc. are often used as polymerization initiators. ing. Among them, dialkyl peroquinone carbonate in particular has high low-temperature activity and excellent productivity, and the obtained polymer has excellent physical properties such as stability, gelling property during processing, and particle size distribution, and is suitable for industrial use. is recognized as the most advantageous polymerization initiator. However, as organic peroxides have higher low-temperature activity, f
] and become unstable at room temperature, increasing the risk of explosion, etc.
Therefore, dedicated refrigeration equipment is required for storage, and even if such equipment were installed, handling during actual use would be dangerous.

To avoid this problem, i.e. instead of using organic peroxide polymerization initiators, alkyl chloroformates,
A method of polymerizing vinyl chloride while producing peroxydicarbonate by simultaneously introducing an inorganic peroxide and an alkali such as an alkali metal hydroxide or hydrogen carbonate into a polymerization vessel is disclosed, for example, in U.S. Patent No. 3.02 J. , 2 g
/ issue, Tokuko Show 31. -Proposed in No. 32Q2, etc.

However, the polymer produced by this method has quality defects such as extremely irregular particle morphology and poor thermal stability and gelling properties, and has no commercial value and is difficult to commercially implement. Met.

As a result of intensive research in order to overcome the above-mentioned drawbacks, the present inventors surprisingly found that by using ammonia as the alkali and keeping the oxygen concentration within the polymerization system below a specific value before the start of polymerization, they were able to achieve an extremely They discovered that high quality polymers can be produced and completed the present invention.

An object of the present invention is to provide an improved method for polymerizing vinyl chloride and the like while producing a polymerization initiator in a polymerization vessel.

Therefore, the gist of the present invention is that alkyl formate,
When polymerizing vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable with it in the presence of an inorganic peroxide and an alkali, ammonia is used as the alkali, and the oxygen concentration in the polymerization system is controlled before the start of polymerization. The present invention provides a method for producing a vinyl chloride polymer, characterized in that the amount of vinyl chloride is 0.00 ppm or less based on all monomers.

The present invention will be explained in detail below.

The vinyl chloride polymer produced by the method of the present invention is a copolymer obtained by copolymerizing a homopolymer of vinyl chloride and a mixture of vinyl chloride and a monomer copolymerizable therewith. Examples of monomers copolymerizable with vinyl chloride include ethylene, propylene, butene, pentene/
, butadiene, styrene, α-methylstyrene, acetic acid,
Vinyl ester q- or allyl esters such as caproic acid, caprylic acid, benzoic acid, dialkyl maleic acid or fural acid esters with the number of carbon atoms in the alkyl group / ~1r (C, ~1.), acrylonitrile, vinylidene chloride, Vinylidene cyanide, alkyl vinyl ether of C1-, 2-alkyl groups, N-vinylpyrrolidone, vinylpyridine, vinylsilanes, alkyl groups C1-, 6
Acrylic acid alkyl esters and methacrylic acid alkyl esters are included, and at least one of these is added in an amount of 0.07 to 0 parts by weight, preferably 5 to 30 parts by weight, based on 10θ parts by weight of vinyl chloride. It can be copolymerized with

The alkyl halogenoformate used in the method of the present invention is represented by the following general formula.

1 0-C-X [In the formula, R is an alkyl group which may have a branched chain, and X represents a chlorine atom, a bromine atom, or a fluorine atom, respectively. ] The alkyl group R preferably has a carbon atom number/~g,
Further, the halogen atom X is generally a chlorine atom. Examples of the alkyl halogenoformate include methyl chloroformate (methyl chloroformate), ethyl chloroformate, n-propyl chloroformate, isopropyl chloroformate, n-butyl chloroformate, isobutyl chloroformate, SθC
-butyl chloroformate, tert-butyl chloroformate, n-amyl chloroformate, isoamyl chloroformate, n-hexyl chloroformate, n-hebutyl chloroformate, n-octyl chloroformate, coete Examples include hexyl chloroformate. However, it is not limited to these.

Therefore, the amount of alkyl halogenoformate used varies depending on the amount of inorganic peroxide or ammonia used, which will be described later, but in order to complete the polymerization reaction, it should be at least 0.0 parts by weight per 100 parts by weight of monomers. In particular, it is preferably used in a range of 0.0 to 0.0 parts by weight. / part by weight or more, careful attention is required since controlling the polymerization reaction tends to be difficult and the quality of the polymer tends to deteriorate.

The inorganic peroxide used in the method of the present invention is not particularly limited as long as it reacts with the above-mentioned alkyl halide formate and ammonia to produce dialkylveroxine carbonate, but for example, hydrogen peroxide, peroxide, etc.)
IJum, potassium peroxide, barium peroxide, magnesium peroxide, sodium hydrogen peroxide;
,O.

NaBO3-H, 02.3H20, etc.) can also be used.

Among these, it is particularly preferable to use hydrogen peroxide since no impurities are mixed in during the polymerization process. The concentration of hydrogen peroxide is not particularly limited as long as it is a commonly available aqueous solution, but a concentration of 30 to 35% is desirable for ease of handling and to reduce the introduction of excess water into the polymerization system. .

Therefore, the amount of hydrogen peroxide used is preferably 1 to 5 moles per mole of the alkyl halide formate used.

Furthermore, the ammonia used in the method of the present invention can be in any state, such as by blowing ammonia gas into water present in the polymerization system, or by adding commercially available ammonia water. The amount of ammonia used is preferably in the range of 0.2 to 10 moles per mole of alkyl halogenoformate.

When the amount of inorganic peroxide and ammonia used is less than the above-mentioned ratio, the conversion to dialkylveroxine carbonate, which acts as a polymerization initiator, is not sufficient, and on the other hand, when the amount used is more than the above-mentioned ratio, inorganic peroxide Most of the polymers and ammonia remain in the polymerization system without taking part in the reaction, which is not only disadvantageous economically but also tends to cause deterioration in the quality of the polymer.

In the method of the present invention, the timing and order of addition of the alkyl halogenoformate, inorganic peroxide, and ammonia to the polymerization system are not particularly limited. Since these three polymerization initiator systems function as polymerization initiators only when they coexist, it is also possible to first introduce the three components into the polymerization system and then introduce the remaining components immediately before the start of polymerization.

In the method of the present invention, the oxygen concentration in the polymerization system at the start of polymerization is set to /0 with respect to the vinyl chloride monomer or copolymerizable monomer.
It is essential to keep the amount below 0 ppm. The oxygen concentration within the polymerization system can vary depending on the degassing conditions, but under normal degassing conditions it decreases only to about 1/00 ppm at most. As a way to avoid further reducing the amount of oxygen, there are two ways to avoid further reduction: ■ Increase the temperature during deaeration, increase the deaeration and nitrogen gas (
2) It is possible to adopt various methods such as increasing the number of repetitions of pressing back, or (2) a combination of these methods. Oxygen concentration is / 00
If polymerization is carried out in a state where the amount exceeds ppm, the resulting polymer tends to have poor thermal stability.

To carry out the method of the present invention, for example, water containing a suspending agent or an emulsifying agent is placed in a polymerization container, the oxygen concentration in the container is reduced to 9 m or less by the method described above, and chloride is added to the polymerization container. Vinyl or a monomer copolymerizable therewith is charged, then an alkyl halogenoformate, an inorganic peroxide and ammonia are introduced under pressure, and suspension or emulsion polymerization is carried out at a temperature of 30 to 70C. The method of the present invention is most preferably employed in suspension polymerization. The suspending agent used in the method of the present invention is
Although not particularly limited, water-soluble polymeric substances such as partially saponified polyvinyl alcohol, hydroxypropyl methylcellulose, vinyl acetate-maleic anhydride copolymer, polyvinylpyrrolidone, and gelatin can be used alone or in combination. . In addition, nonionic emulsifiers such as sorbitan monolaurate, sorbitan monooleate, al or polyoxyethylene derivatives thereof, pentaerythritol monolaurate, pentaerythritol monooleate, etc.
Examples include surfactants, anionic surfactants such as sodium dodenlebenzenesulfonate, and sodium lauryl sulfate. Kowara@turbidity and emulsifier can be used together.

In addition to the above-mentioned polymerization initiator system, the process of the present invention may also be carried out using conventional, already prepared polymerization initiators, such as dialkyl peroxides.

Organic peroxides such as noarsilver oxide, alkyl peroxy esters, dialkyl peroxycarbonate, etc. or azonium compounds may be used in combination. When a polymerization initiator is used in combination, favorable results can often be obtained by controlling the polymerization rate.

In the method of the present invention, a dialkyl peroxydicarbonate is produced from an alkyl halide formate present in a monomer such as vinyl chloride and an inorganic peroxide present in an aqueous medium,
By-produced hydrogen halides and the like are trapped by ammonia coexisting in the aqueous medium, forming a suitable polymerization initiation catalyst system. According to the present invention, there is no need for special refrigeration equipment associated with the use of dialkyl peroxydicarbonate as a polymerization initiator, and there is no danger during handling. A high-quality vinyl chloride polymer that is exactly the same as the one obtained was obtained.

The method of the present invention will be explained in detail below using examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example/ After charging partially saponified polyvinyl acetate/102 and deionized water/Act into a stainless steel polymerization vessel with an internal volume of 300 tons, the inside of the polymerization system was degassed, and finally the internal pressure of the polymerization vessel was reduced to O (gauge) using N2. The pressure was returned until it slightly exceeded the pressure (pressure). The amount of residual oxygen in the polymerization vessel is determined by gas chromatography for the gas phase collected from the upper nozzle of the polymerization vessel, and for the liquid phase by the Winkler method after sampled from the bottom nozzle. The monomer concentration was calculated from the total view.

Next, 110 ky of vinyl chloride monomer was charged into this, and then ethyl chloroformate s, z, g t
(o, o q g for ioo parts by weight of vinyl chloride monomer
(equivalent to parts by weight), 35% hydrogen peroxide solution y 7 y (H
1.30 thiammonia water (equivalent to 0.075 parts by weight as NH3) was continuously charged.

At the polymerization temperature sgC, the pressure in the polymerization system is 1 toge/cr/l.
After continuing the polymerization in a trench showing a drop of , unreacted vinyl chloride monomer was collected and dehydrated and dried to obtain a vinyl chloride polymer.

In this system, the oxygen concentration in the polymerization system at the start of polymerization is 2
g ppm, reaction time was 7 hours λθ minutes. (See Table 1) Example 2, Comparative Example 1. ．． 2. Polymerization was carried out in the same manner as in Reference Example, except that only the oxygen concentration in the polymerization system and the polymerization initiator system were changed.

The results are shown in Table 7. The amount of the polymerization initiator system charged is expressed in parts by weight based on 700 parts by weight of the pure monomer.

/ The vinyl chloride polymer thus obtained was subjected to a thermal stability test, a fish eye test, and a particle size distribution measurement, and the evaluation results are shown in Table 2.

The evaluation method is as follows.

Thermal stability test: 700 parts by weight of vinyl chloride polymer, 3 parts by weight of dioctyl phthalate, 3 parts by weight of epoxidized soybean oil, and 0.0 parts by weight of barium stearate. Parts by weight of Q, 0.47 parts by weight of zinc stearate, parts by weight of trinonylphenylsulfite O,S, and 0.4 parts by weight of octyltin. / parts by weight are added and mixed, and a sheet is obtained by roll kneading. Roll conditions are roll surface temperature/AOC, roll gap 0.5mm, kneading time S.
It is a minute. The obtained sheet was hung at 770C with the gear open, and the time until it turned black was measured to determine the thermal stability. The longer the blackening time, the better the thermal stability.

Fish eye test: vinyl chloride polymer io.

Parts by weight, 50 parts by weight of dioctyl phthalate, parts by weight of calcium stearate, and carbon blank/
5 parts by weight were added and mixed, roll kneading was carried out for S minutes under the conditions of a surface temperature of 760 C and a roll gap of 0.6 rMI, and after 5 minutes, the film was taken out with a roll gap of 0.77 rfrM.

The number of fish eyes in 30 crd at any location on this film was read to check the quality of the fish eyes.

Particle size distribution measurement: Using a Tylθr standard sieve, the passing rate of each mesh was cumulatively shown.

Table 2 Number Example Comparative example Reference /2/23 Thermal stability (min) /110 /QO10/20
/, tlO Fisheye, 7 2 5A 63 (pieces/30 crl, ) grains 40me 77'' 100 100 74
・910010゜As is clear from this result, when sodium hydroxide is used as the alkali in a polymerization initiator system consisting of ethyl chloroformate, hydrogen peroxide, and an alkali, the heat of the resulting polymer increases. Stability,
Fish eyes are of very poor quality, have an unsatisfactory particle size distribution, and are of no commercial value.

Furthermore, even if ammonia is used as the alkali, if the oxygen concentration in the polymerization system is higher than 1/00 ppm, the thermal stability will not be improved sufficiently. On the other hand, it is clear that extremely high quality polymers can be obtained by using ammonia as the alkali and further reducing the oxygen concentration to j/00 ppm or less.

Patent applicant Mitsubishi Monsanto Chemical Co., Ltd. Representative
Person Patent attorney Hase-yō - others/names

Claims (1)

[Claims] tl) In polymerizing vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable therewith in the presence of an alkyl halogenoformate, an inorganic peroxide, and an alkali,
Ammonia is used as the alkali, and the oxygen concentration in the polymerization system before the start of polymerization is set to / 00 ppm based on the total insect mass.
A method for producing a vinyl chloride polymer characterized by the following (2) A method for producing a vinyl chloride polymer according to claim 1, wherein the alkyl halide formate is an alkyl chloroformate (3) A method for producing a vinyl chloride polymer according to claim 1, wherein the alkyl halide formate is an alkyl chloroformate The method for producing a vinyl chloride polymer according to claim 7 or 2, wherein the alkyl group may have a branched chain. The method for producing a vinyl chloride polymer according to claim 1, wherein the oxide is hydrogen peroxide.