JPS6230204B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to an improved method for polymerizing vinyl monomers. Conventionally, known methods for polymerizing vinyl monomers include suspension polymerization, emulsion polymerization, solution polymerization, gas phase polymerization, and bulk polymerization.
In all of these polymerization methods, there was a problem of polymer scale adhesion on the walls of the polymerization vessel and other parts of the stirring device. In other words, when vinyl monomers are polymerized using these methods, polymer scale adheres to the inner walls of the polymerization vessel and parts that come into contact with the monomers, such as the stirring device, which reduces the yield of the polymer and the cooling of the polymerization vessel. In addition to reducing performance, this scale flakes off and mixes into the product, reducing the quality of the product. On the other hand, removing this scale requires excessive labor and time. Not only that, but unreacted monomers are adsorbed in this scale, so there is a risk of human injury due to monomers (vinyl chloride, etc.), which has become a very serious problem in recent years. There is a disadvantage. In order to prevent this polymer scale from adhering to the inner walls of the polymerization vessel, for example, polar organic compounds such as amine compounds, quinone compounds, and aldehyde compounds, dyes, and pigments are applied to the inner walls of the polymerization vessel and the stirrer. Method (Tokuko Showa 45-30345
(see Japanese Patent Publication No. 45-30835, etc.), a method of applying a polar organic compound or a dye treated with a metal salt (see Japanese Patent Publication No. 52-24953), a method of applying an electron-donating compound and an electron-accepting compound. (see Japanese Patent Publication No. 53-28347), method of applying an inorganic salt or inorganic complex (Japanese Patent Publication No. 52-28347),
24070) etc. are known. These coating methods provide a remarkable scale prevention effect when using an azo compound catalyst and a peroxide catalyst having a long chain alkyl group as a polymerization catalyst. However, in suspension polymerization of vinyl chloride, for example, when an oil-soluble peroxide catalyst with a solubility in water of 0.2% by weight or more (at 20°C) is used, scale prevention is significantly reduced or almost ineffective. The disadvantage is that it cannot be used. Also, among the monomers, styrene, styrene-
Polymerization of butadiene, acrylonitrile-butadiene-styrene, etc. has the disadvantage that scale prevention is significantly reduced or almost no effect is obtained. The above-mentioned oil-soluble peroxide catalyst having a solubility in water of 0.2% by weight or more can be used as a catalyst for suspension polymerization of vinyl chloride, for example, to provide a good thermal property that does not cause initial coloring during processing. It is extremely important to find an effective method to prevent scale build-up when using such oil-soluble peroxide catalysts, as they are characterized by providing stable and high quality vinyl chloride polymers. This is considered a major technical issue. The present invention aims to provide a method for polymerizing vinyl monomers without such difficulties. Add an aqueous solution of an alkali metal or ammonium salt of a sulfonic acid type or carboxylic acid type dye, or an alkali metal or ammonium salt of an organic sulfonic acid or carboxylic acid having a conjugated double bond to the part that will be in contact with other monomers at a pH value of 7. Apply an aqueous solution prepared by adjusting the following and adding carbon,
The present invention relates to a method for polymerizing vinyl monomers, which is characterized by drying. The present invention provides that when the solvent of the coating agent is water, the use of compounds having σ electrons or π electrons is insufficient for preventing scale adhesion, and that compounds having conjugated double bonds are effective. Aqueous solutions of compounds such as alkali metal or ammonium salts of sulfonic acid-type or carboxylic acid-type dyes and alkali metal or ammonium salts of organic sulfonic or carboxylic acids having conjugated double bonds are alkaline; This method was developed based on the fact that, at best, hardly any scale prevention effect can be obtained, but by adjusting the pH value of this aqueous solution to 7 or less and adding carbon to this aqueous solution, a remarkable scale prevention effect can be brought about. It is. When using the method of the present invention, the medium of the coating liquid as a so-called scale preventive agent is safe and hygienic.
Since it is harmless and non-toxic water, it is extremely advantageous in terms of safety and hygiene compared to coating liquids using organic solvents, and by using this water, the monomers such as the inner wall of the polymerization vessel, stirring blades, stirring shaft, etc. come into contact with each other. This effect can be used in various polymerization methods such as suspension polymerization, emulsion polymerization, and bulk polymerization, regardless of whether the polymerization vessel is made of stainless steel or glass lined. Even if it is, there is an advantage that it can be exhibited without being influenced by the type of monomer, the composition of the polymerization system, the type of polymerization catalyst, etc. Therefore, according to the method of the present invention, polymerizations that were conventionally carried out in glass-lined polymerization vessels can be carried out in stainless steel polymerization vessels, which is a great industrial advantage. Furthermore, when the method of the present invention is applied to the polymerization of vinyl chloride, the adhesion of polymer scale to the inner walls of the polymerization vessel is almost completely prevented, and the resulting polymer has no initial coloring during processing and has good thermal stability. This gives the effect that there are significantly fewer fisheyes and that the material is of high quality. The mechanism by which the method of the present invention significantly prevents the adhesion of polymer scale in a wide variety of polymerizations is probably due to the fact that the compounds in the pH-adjusted aqueous liquid are absorbed onto the walls of the polymerization vessel. Once dried, it becomes insoluble or poorly tolerant to water and is strongly adsorbed to the wall surface, and the surface charge of this coating film soon becomes strongly anionic. This is presumed to be due to the fact that specific adsorption of all dissociated and undissociated molecules present in the polymerization system is suppressed, unlike when a compound or the like is applied. Next, the content of the present invention will be explained in more detail. Examples of the alkali metal or ammonium salts of sulfonic acid type or carboxylic acid type dyes used in the method of the present invention [hereinafter referred to as component (a)], CI Direct Yellow 1, CI Acid Yellow 38, CI Acid Yellow Yellow 3, CI Reactive Yellow 3, CI Direct Orange 2,
CI Direct Orange 10, CI Direct Red 18, CI Assisted Red 52, CI Assisted Red 73, CI Direct Red 186, CI Direct Red 92, CI Basic Red 2, CI Direct Violet 1, CI Direct Violet 22, CI Assisted Red 18 , CI Basic Violet 10, CI Assisted Violet 11, C.
I. Assisted Violet 78, CI Mordant Violet 5, CI Direct Blue 6, CI Direct Blue 71, CI Direct Blue 106, CI
Reactive Blue 2, CI Reactive Blue 4, CI Reactive Blue 18, CI Acid Blue 116, CI Acid Blue 158, CI Mordant Blue 1, CI Mordant Black 1, CI Mordant Black 5, CI Acid Black 2,
Examples include CI Direct Black 38, CI Solbilized Butt Black 1, CI Fluorescent Brightening Agent 30, CI Fluorescent Brightening Agent 32, and CI Azoic Brown 2. In addition, examples of the alkali metal or ammonium salts of organic sulfonic acids or carboxylic acids having a conjugated double bond include α-naphthalene sulfonic acid,
Anthraquinone sulfonic acid, metanilic acid, cyclohexyl sulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfonic acid, abietic acid, isonicotinic acid, benzoic acid, phenylglycine, 3
Examples include alkali metal or ammonium salts of organic sulfonic acids or carboxylic acids having a conjugated double bond, such as -oxy-2-naphthoic acid. In carrying out the method of the present invention, an aqueous solution is prepared in which at least one of the above-mentioned compounds is dissolved at a concentration suitable for coating work, and the pH of this aqueous solution is adjusted to 7 or less. This is preferable from the viewpoint of scale prevention effect, and substances used for this purpose include sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, carbonic acid, perchloric acid, molybdic acid, tungstic acid,
Examples include formic acid, acetic acid, oxalic acid, maleic acid, glycolic acid, lactic acid, thioglycolic acid, and phytic acid, and it is convenient to prepare these as an aqueous solution in advance. In the present invention, carbon is added to the aqueous solution described above, but this addition is not limited to after adjusting the pH. The above-mentioned carbon includes graphite, charcoal, soot, carbon black, and the like. Examples of carbon black include pine smoke, oil smoke, furnace black, lamp black, thermal black, acetylene black, German furnace black, channel black, roller and tooth black, and German naphthalene black. The average particle diameter of these carbons is preferably 1 μm or less. If the average particle diameter is 1 μm, the dispersion will not be stable and it will be difficult to form a dense film, resulting in a decrease in scale prevention ability. In the present invention, (a) an alkali metal or ammonium salt of a sulfonic acid type or carboxylic acid type paint, or an alkali metal or ammonium salt of an organic sulfonic acid or carboxylic acid having a conjugated double bond, and (b) carbon black. The desirable blending ratio is 0.1 parts by weight of component (B) to 100 parts by weight of component (A).
~1000 parts by weight (more preferably 3 to 100 parts by weight)
This provides the advantage that the adhesion of the coating film to the wall of the polymerization vessel becomes stronger. The aqueous solution obtained as described above is applied to the inner wall of the polymerization vessel and other parts that come into contact with the monomer, and the applied surface is thoroughly dried. Alternatively, preheat the inner wall of the polymerization vessel and other parts that come into contact with the monomer (40
~100℃) and apply directly to the heated surface.
In either case, wash with water if necessary after the coated surface is sufficiently dry. Note that when preparing an aqueous solution as a coating solution, the solvent is not limited to water alone, and an organic solvent that is easily miscible with water may be used in combination. In this case, coating and drying after coating can be completed at room temperature without heating. As the organic solvent that is easily miscible with water, alcohol solvents having 1 to 2 carbon atoms, ester solvents, ketone solvents, and the like are used. When the aqueous liquid prepared in this way is applied to the inner wall of a polymerization vessel made of stainless steel or the like, additives may be added to improve the wettability of the aqueous liquid to the inner wall of the polymerization vessel. Monohydric alcohols having 3 to 6 carbon atoms are particularly suitable as this additive, and include n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol. , t-butyl alcohol, n-amyl alcohol, t-amyl alcohol, iso-amyl alcohol, sec-amyl alcohol, sec-hexyl alcohol, etc.
The purpose of improving wetting can be achieved by adding the species or two or more species at a concentration of approximately 1 to 20% by weight in the final aqueous liquid. In the present invention, the amount of coating on the walls of the polymerization vessel etc. may be about the same as when using conventional coating agents. In other words, 0.001 for the inner wall of the polymerization vessel, stirrer, etc.
g/m ² or more, the effect of preventing scale adhesion is fully exhibited. The method of the invention is applied to the polymerization of vinyl monomers, and specific examples of this monomer include vinyl halides such as vinyl chloride, vinyl esters such as vinyl acetate and vinyl propionate, and acrylic acid. , methacrylic acid or their esters or salts, maleic acid or fumaric acid, and their esters or anhydrides, diene monomers such as butadiene, chloroprene, isoprene, as well as styrene, acrylonitrile, vinylidene halides, vinyl ethers, etc. can give. When polymerizing one or more of these monomers, the purpose of scale prevention can be effectively achieved regardless of the polymerization format or polymerization recipe. For example, suspension polymerization or emulsification of vinyl monomers Additives added to the polymerization system during polymerization include partially saponified polyvinyl alcohol, clouding agents such as methylcellulose,
Anionic emulsifiers such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and sodium dioctyl sulfosuccinate, nonionic emulsifiers such as sorbitan monolaurate and polyoxyethylene ether, fillers such as calcium carbonate and titanium oxide, and tribasic lead sulfate. , stabilizers such as calcium stearate dibutyltin dilaurate and dioctyltin mercaptide, lubricants such as rice wax and stearic acid, plasticizers such as DOP and DBP, complex transfer agents such as trichlorethylene and mercaptans, PH regulators, diisopropyl peroxydi carbonate, α・α′-azobis-
Scale adhesion is well prevented in a polymerization system in which a polymerization catalyst such as 2,4-dimethylvaleronitrile, lauroyl peroxide, potassium persulfate, cumene hydroperoxide, p-menthane hydroperoxide, etc. is present. The method of the present invention is particularly preferably carried out using vinyl halides such as vinyl chloride, vinylidene halides, or their (co)polymers by suspension polymerization or emulsion polymerization of monomer mixtures mainly composed of them. For the production of polymer beads, latex, SBR, NBR, etc. of polystyrene, polymethyl methacrylate, polyacrylonitrile in stainless steel polymerization vessels,
Manufacture of synthetic rubbers such as CR, IR, IIR (these synthetic rubbers are usually manufactured by emulsion polymerization), ABS
This is the case in the production of resin. To explain the relationship with the polymerization initiator when the method of the present invention is applied to suspension polymerization of vinyl chloride, etc., first, the solubility in water of the conventionally known main oil-soluble peroxide catalysts is as follows. It is as follows. Solubility in water (20℃) Di-2-ethylhexyl peroxydicarbonate (OPP) 0.04 Lauroyl peroxide (LPO) 0.003 3,5,5-trimethylhexanoel peroxide (L-355) 0.05 α-cumyl peroxy Neodecanoate (L-
188) 0.01 Di-2-ethoxyethyl peroxydicarbonate (EEP) 0.41 Bis-3-methoxybutyl peroxydicarbonate (MPC) 0.24 Di-butoxyethyl peroxydicarbonate (BEP) 0.21 (*1) Catalyst material The symbols added to the name in brackets are abbreviations, and these abbreviations will be used below unless otherwise specified. (*2) Solubility is a value measured by thoroughly dispersing an oil-soluble peroxide catalyst in water at 20°C, centrifuging it, and then titrating the aqueous layer by iodometry. Among the oil-soluble peroxide catalysts mentioned above, OPP,
For materials such as LPO, L-355, and L-188, which have extremely low solubility in water, the polymers obtained using them (vinyl chloride polymers) resist initial discoloration during processing and have good thermal stability. Although there is a problem that there is no
Catalysts having a solubility in water of 0.2 or more at 20°C have the excellent feature of not having such problems. Therefore, it is desirable to use a catalyst with a solubility of 0.2 or more, but this has conventionally had the disadvantage of large scale adhesion. According to the present invention, even when such a catalyst is used, scale adhesion can be significantly prevented. Next, examples of the present invention will be shown, and each physical property value was determined according to the following method. Measuring method for fish eye (units): 100 parts by weight of polymer, 50 parts by weight of DOP, 1 part by weight of dibutyltin dilaurylate, 1 part by weight of cetyl alcohol
A mixture of 0.25 parts by weight of titanium oxide, 0.25 parts by weight of carbon black, and 0.25 parts by weight of carbon black was kneaded with two rolls at 150°C for 7 minutes to form a sheet with a thickness of 0.2 ^mm. The number of fish eyes contained in a winning sheet was investigated. Method for measuring thermal stability (minutes): A mixture of 100 parts by weight of polymer, 1 part by weight of dibutyltin malate and 1 part by weight of stearic acid was
The test pieces were kneaded for 10 minutes with two rolls (roll spacing: 0.7 mm) at 180° C. and heated in a gear oven at 180° C., and the time required for blackening was measured. Example 1 A coating agent as shown in Table 1 was applied to the inner wall of a stainless steel polymerization vessel with an internal volume of 1000 and the part of the stirrer that would come into contact with the monomer, and the coated surface was heated to 90°C.
It was dried by heating for a few minutes and then washed with water. In this coated polymerization vessel, 500 kg of water in which 150 g of partially saponified polyvinyl alcohol and 50 g of hydroxypropyl methylcellulose were dissolved, a polymerization initiator of the type shown in Table 1, and 250 kg of vinyl chloride were added.
Kg was charged and polymerized at 50°C for 10 hours. When the scale adhesion amount was examined in each experiment, the results were as shown in Table 1. As can be seen from these experimental results, the amount of scale adhesion varies greatly depending on the type of polymerization initiator.
EEP, MPC and BEP are experiments No. 5 to 7, No. 12 to
14, Nos. 19 to 21, a large amount of scale adheres, but by using the coating agent of the present invention, the amount of scale adhesion can be reduced to that of Experiment Nos. 26 to 21.
As shown in 28, it is extremely rare.

【table】

[Table] Example 2 The aqueous coating liquid (*) of the coating agent shown in Table 2 was applied to the inner wall and stirrer part of a polymerization vessel (made of stainless steel) with an internal volume of 100 mm, and then heated and dried at 90°C for 10 minutes. The coated surface was washed with water. (*) Coating solution: Dissolve (a) and (b) in water at a total concentration of 0.5% by weight and adjust the pH to 2.5 with phosphoric acid. Into the coated polymerization vessel, add 40 kg of water and vinyl chloride. 17 kg of monomer, 3 kg of vinyl acetate monomer, 12 g of partially saponified polyvinyl alcohol, 4 g of hydroxypropyl methyl cellulose, MPC6 as a polymerization initiator
g, trichlorethylene 200g, pre-stirred for 15 minutes, then raised the temperature to 58℃ and stirred for 12 minutes.
Polymerized for hours. When the amount of scale attached to the polymerization vessel was examined in each experiment, the results were as shown in Table 2.

【table】

[Table] Example 3 An aqueous coating solution (*) of the coating agent shown in Table 3 was applied to the inner wall and the stirrer part of a stainless steel polymerization vessel with an internal volume of 500 and equipped with a stirrer, and the mixture was heated and dried at 90°C for 10 minutes. The coated surface was then washed with water. (*) Coating solution: Dissolve (a) and (b) in water at a total concentration of 1.0% by weight, adjust the pH to 3.0 with phosphoric acid, and further add isobutanol to this at a concentration of 10% by weight. Add 200kg of water and styrene to this coated polymerization vessel.
100 kg of calcium phosphate, 10 g of sodium dodecylbenzenesulfonate, and 20 g of MPC were charged, and polymerization was carried out at 60°C for 5 hours while stirring. After the completion of polymerization, the amount of scale attached was examined.
It was as shown in Table 3.

【table】

Claims (1)

[Claims] 1. When polymerizing vinyl monomers, apply an alkali metal or ammonium salt of a sulfonic acid type or carboxylic acid type dye, or an organic sulfonic acid having a conjugated double bond, to the inner wall of the polymerization vessel and other parts that come into contact with the monomers. Or an aqueous solution of an alkali metal or ammonium salt of carboxylic acid.
A method for polymerizing vinyl monomers, which comprises applying an aqueous solution prepared by adjusting the pH value to 7 or less and adding carbon, and drying the solution.