JPH0210163B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention deals with the generation of polymer scale on the surface of the polymerization vessel and equipment attached to the polymerization vessel when polymerizing vinyl monomers, diene monomers, or olefin monomers, and the prevention of this on the surface of the polymerization equipment. The present invention relates to a method for preventing adhesion. Various polymers are known for polymerizing the above monomers, and various methods are used industrially. In these polymerization methods, during the polymerization process,
Polymer scale often adheres to the inner walls of polymerization vessels, stirring blades, baffles, various piping installed in polymerization vessels, and the walls of reflux condensers, regardless of whether they are in the gas or liquid phase of the polymerization equipment. If polymerization is continued without removing scale attached to these devices, the amount of scale will further increase, worsening heat conduction on the walls of the polymerization vessel, and not only will it reduce the heat removal ability of the polymerization vessel, but will also prevent normal polymerization. As scale gets mixed into the product, the quality of the product deteriorates. In order to prevent such harmful effects, it is necessary to timely remove scales attached during the polymerization reaction.
This requires a great deal of labor, equipment, expense, etc.
Furthermore, there is a disadvantage that the operating rate of the polymerization vessel is reduced. For example, when vinyl chloride monomer or a mixture of vinyl chloride monomers copolymerizable with vinyl monomer is polymerized by suspension in an aqueous medium, a film or a partial block is formed on the inner wall of the polymerization vessel and the stirring blade. A type of polymer, so-called scale, is generated. If the next polymerization reaction is carried out without removing this scale, the amount of scale will further increase, impairing heat conduction in the walls of the polymerization vessel, and reducing the heat removal ability of the polymerization vessel. In addition, since scale is mixed into normal polymer particles, when the polymer is processed into a film, a large amount of fish eyes are generated, which extremely deteriorates the quality of the product. In order to prevent these adverse effects, scale generated in the previous polymerization reaction must be removed before starting the polymerization reaction. Normally, methods such as spraying high-pressure water are used to remove this scale, but this requires a great deal of labor and equipment, and furthermore, requires a long period of cleaning time, which reduces the operating frequency of each polymerization reactor. descend. In addition, the toxicity of vinyl chloride monomer has become a problem in recent years, and manual cleaning of equipment inside the polymerization reactor has been avoided for safety reasons in the working environment. is becoming difficult. Moreover, it is impossible to prevent scale build-up during polymerization by any scale removal method, and cleaning must be performed after each batch of polymerization. In order to avoid such disadvantages, various methods have been known to prevent scale from adhering to the inner walls of polymerization vessels and the like. For example, methods are known in which a certain type of compound is applied to the inner wall of a polymerization vessel, or a method in which a certain type of compound is added to the polymerization system. Known coating agents used in the former method include dyes (Japanese Patent Publication No. 53-28347) and free radical inhibitors (Japanese Patent Application Laid-open Nos. 48-44375 and 1972-103981). This method requires frequent application of the lubricant and is not necessarily an advantageous method. In addition, as the latter additives to be added to the polymerization system, there are alkaline agents (Japanese Patent Publication No. 45-37988), oxidizing agents (Japanese Patent Publication No. 46-20821), alkali metal salts of phosphoric acid (Japanese Patent Publication No. 47-34690), etc. Although known, these additives have a negative effect on the polymerization reaction and deteriorate the quality of the polymerized product, so this is not always an advantageous method. The present inventors have conducted various research on metal materials that physically do not cause scale formation or adhesion for materials such as polymerization vessel walls, and have found that scale is difficult to form on the surface of materials containing a relatively high content of titanium. We discovered this and arrived at the present invention. That is, when polymerizing or copolymerizing vinyl monomers, diene monomers, or olefin monomers, the present invention uses a polymerization device that uses a titanium alloy in the reactant contact portion of the polymerization vessel. This invention relates to a polymerization method that hardly causes scale adhesion to the inner walls of the vessel. As a method of preventing scale adhesion by limiting the material of the polymerization equipment, special metal materials used for the walls of the polymerization vessel include aluminum oxide (Special Publication No. 49-29305), copper-nickel alloy (Special Publication No. 1973-29305),
33270) and Nickel (Japanese Unexamined Patent Publication No. 110480/1983), these methods are not necessarily satisfactory in terms of the degree of reduction in scale generation and adhesion. According to the present invention, there is almost no scale generation, and there is no need to frequently clean the inner walls of the polymerization vessel.
It is possible to carry out polymerization continuously for a long period of time without deteriorating the quality of the obtained polymer product. This is due to properties specific to titanium, and is a unique effect that cannot be obtained using other metal materials. When a titanium alloy is used in the present invention, a titanium alloy with chromium, molybdenum, manganese, aluminum, vanadium, tin, niobium, etc., or a titanium carbide or titanium nitride is used. The content of components other than titanium in these alloys or compounds is preferably less than 10% from the viewpoint of effectiveness and practicality. The titanium alloy or the titanium compound described above may be used in a polymerization device such as a polymerization vessel, a stirrer, or the like, where monomers and polymers come into contact during the polymerization reaction. Alternatively, the surface of the polymerization equipment may be coated with these. Moreover, these metals and compounds may of course be used in combination. Furthermore, when performing a polymerization reaction using polymerization equipment that uses these titanium, titanium alloys, or titanium compounds as the material for the contact surface of the polymer, additives that have the effect of preventing scale adhesion are added to the polymerization system. This further improves the scale adhesion prevention effect. Examples of the additives used include the above-mentioned alkali agents and oxidizing agents. The polymerization method used in the present invention is not particularly limited, and includes suspension polymerization, emulsion polymerization, bulk polymerization, solution polymerization, and others. The monomers used include vinyl monomers, diene monomers, olefin monomers, etc., such as acrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, styrene, acrylic ester, and methacrylic acid. Examples include esters, maleic acid and other vinyl monomers, butadiene, chloroprene and other diene monomers, ethylene, propylene, butene-1, pentene and other olefin monomers. These monomers can be used for homopolymerization or copolymerization of two or more types, and also for copolymerization of these monomers and polymers or copolymers of these monomers. For example, when carrying out suspension polymerization in the present invention, partially saponified polyvinyl acetate, cellulose derivatives such as methyl cellulose, acrylic acid copolymers, maleic anhydride copolymers, gelatin, starch, and other conventional dispersants are used as dispersants. is used. In addition, when performing emulsion polymerization, anionic emulsifiers such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, calcium laurate, sodium higher alcohol sulfate, sodium dialkyl sulfosuccinate, polyoxyethylene alkyl ether, polyoxyethylene alkphenol, etc. Nonionic emulsifiers such as ether, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester are used. Further, as the polymerization catalyst used for the polymerization in the present invention, water-soluble or oil-soluble catalysts, metal compound catalysts for ionic polymerization, etc. are used. Examples of the water-soluble polymerization catalyst include hydrogen peroxide, ammonium persulfate, potassium persulfate, and redox polymerization catalysts such as a combination of ammonium persulfate and ferrous salt. Examples of the oil-soluble catalyst include benzoyl peroxide and lauroyl. Peroxide, tert-butyl peroxypivalate,
Organic peroxides such as diisopropyl peroxydicarbonate, dioctyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, acetylcyclohexylsulfonyl peroxide, 2.2′ azobisisobutyronitrile,
2.2′azobis2.4-dimethylvaleronitrile,
Examples of azo compounds such as 2.2′ azobis-4-methoxy-2.4-dimethylvaleronitrile and other polymerization catalysts for olefins include alkylaluminum,
Also used is a so-called Ziegler-Nutter catalyst that uses a combination of an organoaluminium compound such as an alkyl aluminum sesquihalide and a transition metal compound such as titanium tetrachloride or titanium trichloride. EXAMPLES Next, the present invention will be specifically explained using Examples, but the scope of the present invention is not limited thereby. In addition, the scale adhesion amount in Examples 1 to 7 is as follows:
The weight of scale attached to the surface of a test piece (5 cm x 10 cm, thickness 0.3 cm) attached to the inner wall of the polymerization vessel after completion of polymerization is expressed as the weight per unit area of the test piece. Example 1 After attaching the test piece shown in Table 1 to the wall inside a stainless steel autoclave, 250 parts by weight of pure water and partially saponified polyvinyl acetate were added.
After adding 0.25 parts by weight of 2.2'azobis2.4-dimethylvaleronitrile and 0.05 parts by weight, 100 parts by weight of vinyl chloride monomer was added to the autoclave under reduced pressure. Heating was then started with stirring and heated to 57°C for 10
After continuing polymerization for a period of time, unreacted monomers were discharged and the polymer was taken out. Table 1 shows the amount of scale deposited when the same polymerization reaction was repeated five times with the test piece attached as it was. Nos. 7 to 8 are results according to the present invention, and Nos. 1 to 8 are results according to the present invention.
6 is a comparative example, and only in this example, the scale adhesion amount of the first batch is shown.

【table】

[Table] Example 2 After installing the test piece shown in Table 2 into the same autoclave used in Example 1, 300 parts by weight of pure water, 0.6 parts by weight of sodium dodecylbenzenesulfonate, and persulfuric acid were added. 0.1 part by weight of potassium was added. After purging with nitrogen, the pressure inside the autoclave was reduced and 100 parts by weight of vinyl chloride monomer was added. Next, heating was started while stirring, and after continuing polymerization at 53° C. for 10 hours, unreacted monomers were discharged and the polymer was taken out. With the test piece attached as is,
Table 2 shows the amount of scale deposited when the same polymerization reaction was repeated five times. Nos. 7 to 8 are results according to the present invention, and Nos. 1 to 8 are results according to the present invention.
6 is a comparative example. Further, only the scale adhesion amount of the first batch is shown for Comparative Examples Nos. 1 to 6.

[Table] Example 3 After installing the test piece shown in Table 3 in the autoclave as in Example 1, add 300% pure water.
parts by weight, partially saponified polyvinyl acetate 0.6 parts by weight,
0.06 parts by weight of 2.2′azobis2.4-dimethylvaleronitrile and 10 parts by weight of vinyl acetate monomer were added. After the autoclave was purged with nitrogen and the pressure inside the autoclave was reduced, 90 parts by weight of vinyl chloride monomer was charged. Next, heating was started while stirring, and after continuing polymerization at 58° C. for 8 hours, unreacted monomers were collected and the polymerized product was taken out. Furthermore, Table 3 shows the amount of scale deposited when the polymerization reaction of the same recipe was repeated five times with the test piece attached as it was. Nos. 7 to 8 show the results according to the present invention, and Nos. 1 to 6 show the results according to the present invention.
shows a comparative example. In addition, only for Comparative Examples Nos. 1 to 6, the scale adhesion amount after the first batch is shown.

[Table] Example 4 In a stainless steel autoclave with an internal volume of 10,
Added 0.3 parts by weight of lauroyl peroxide,
After purging with nitrogen, the pressure was reduced and 100 parts by weight of vinyl chloride monomer was added. Next, heating was started while stirring at a stirring speed of 1000 rpm, and polymerization was carried out at an internal temperature of 60° C. for 2 hours. On the other hand, after installing the test piece shown in Table 4 into the autoclave used in Example 1, the pressure inside the autoclave was reduced, 400 parts by weight of vinyl chloride monomer was charged, and the mixture was stirred at a speed of 100 rpm. While doing so, the internal temperature was raised to 60℃, and the polymerized contents polymerized in the autoclave described in step 10 above were transferred to this, and the polymerization was continued for an additional 10 hours to recover unreacted monomers and take out the polymerized product. . In addition, test
Table 4 shows the amount of scale deposited when the same polymerization reaction was repeated five times with the pieces attached as they were. Nos. 7 and 8 show the results according to the present invention.
Nos. 1 to 6 show comparative examples. Also, this No. 1 to 6
Only for the comparative example, the scale adhesion amount after the first batch is shown.

[Table] Example 5 A reflux condenser and a dropping funnel were attached to the top of the stainless steel autoclave used in Example 1, and the test pieces shown in Table 5 were attached to the inner wall, and the interior was replaced with nitrogen. Add to this 4 parts by weight of disproportionated rosin soap (potassium salt) and caustic soda.
0.4 parts by weight of sodium sulfite, 0.3 parts by weight of formalin and naphthalene sulfonic acid condensate, and pure water.
An emulsion dissolved in 100 parts by weight was introduced. then
2.6-di-t-butyl-p-cresol 0.1 part by weight,
Then, 100 parts by weight of chloroprene monomer in which 0.2 parts by weight of n-dodecyl mercaptan was dissolved was added and stirred to emulsify. When the internal temperature reaches 40°C by continuing to stir, an aqueous solution of 1 part by weight of potassium persulfate dissolved in 100 parts by weight of pure water is added dropwise from the dropping funnel at a rate that allows the entire amount to be dropped in 5 hours. dripped. After continuing the polymerization for 4 hours, the polymerization was stopped by adding a polymerization stopper (an aqueous solution of phenothiazine, 4-t-butylcatechol, benzene, sodium lauryl sulfate, and the soda salt of formalin and naphthalene sulfonic acid condensate). The liquid was taken out from the autoclave. Table 5 shows the amount of scale attached to the test piece when the same polymerization reaction was repeated five times with the test piece attached. Here, No. 7-8 shows the results according to the present invention,
Nos. 1 to 6 show comparative examples. In addition, only Comparative Examples Nos. 1 to 6 showed scale adhesion after the first batch was completed.

[Table] Example 6 After attaching the test piece shown in Table 6 to the inner wall of the autoclave used in Example 1, the lid was closed and the interior was replaced with nitrogen, and then the autoclave was heated under a nitrogen stream. A solution prepared by diluting 100 parts by weight of hexane, 0.1 parts by weight of diethylaluminum chloride, and 0.09 parts by weight of titanium trichloride (Ticl3.1/3AIc13) with 40 parts by weight of n-hexane was charged in this order. Next, the flow of nitrogen was stopped, the temperature inside the can was raised to 70℃ while stirring, and then ethylene gas was continuously supplied so that the pressure inside the can was 10 Kg/cm ² (gauge pressure). While doing so, polymerization started. 1
After constant pressure polymerization was carried out at 10 kg/cm ² (gauge pressure) for an hour, the supply of ethylene was stopped, and unreacted ethylene gas was then discharged to the outside of the can. After release of ethylene, the polymer was taken out. Furthermore, Table 6 shows the amount of scale deposited on the test piece when the same polymerization reaction was repeated five times with the test piece attached. Here, Nos. 7 and 8 represent the results according to the present invention.
1 to 6 show comparative examples. Further, only for Comparative Examples Nos. 1 to 6, the amount of scale adhesion after the first batch was completed is shown.

【table】

[Table] Example 7 After attaching the test piece shown in Table 7 to the inner wall of the autoclave used in Example 1, pure water was added.
200 parts by weight, 10 parts by weight of ethylene/vinyl acetate copolymer (vinyl acetate content 15%), 0.2 parts by weight of partially saponified polyvinyl acetate, and 0.1 part by weight of lauroyl peroxide were added. After closing the lid and evacuating the inside of the autoclave, 100 parts by weight of vinyl chloride monomer was added. Next, heating was started while stirring, and after continuing polymerization at 60° C. for 10 hours, unreacted monomers were discharged and the polymerized product was taken out. The amount of scale attached to the test piece is shown when the same polymerization reaction is repeated 5 times with the test piece attached as is.
7. Now, Nos. 7 and 8 show the results according to the present invention, and No. 1
-6 show comparative examples. In addition, only for Comparative Examples Nos. 1 to 6, the scale adhesion amount after the first batch is shown.

[Table] Example 8 Inner Capacity 1 Using an autoclave made of stainless steel (SUS316) and an autoclave whose inner surface was coated with the metal materials shown in Table 8, an example was carried out.
Polymerization was carried out using the same recipe as in 1. After the polymerization was completed, the polymerized product was taken out, THF was poured into the autoclave, the lid was closed again, and the temperature inside the autoclave was adjusted.
The mixture was stirred for about 1 hour while maintaining the temperature at 60°C. Next, transfer the THF solution in which the polymer scale on the vessel wall has been dissolved into approximately 10 containers, and gradually pour methanol into this THF solution while stirring to reprecipitate the dissolved polymer, filter and dry it. The weight was measured. Table 8 shows the amount of scale in terms of weight per unit area of the inner wall of the autoclave.
No. 1 and No. 2 are comparative examples, showing the amount of scale at the end of the first batch, and No. 3 is an example in which the amount of scale adhesion was measured after repeating 5 batches of polymerization and then performing the above THF treatment. be.

【table】

Claims (1)

[Claims] 1. In a method for preventing the formation of polymer scale and adhesion to the surface of polymerization equipment when polymerizing or copolymerizing vinyl monomers, diene monomers, or olefin monomers, The material of the polymerization equipment in the contact area contains more than 90% titanium,
Chromium, molybdenum, manganese, aluminum,
A method for preventing the formation and adhesion of polymer scale, characterized by using a polymerization device made of an alloy with a metal selected from vanadium, tin, and niobium and/or a titanium compound selected from titanium carbide and titanium nitride.