JPS6152841B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for removing synthetic polymeric substances, and more particularly, to a method for removing synthetic polymeric substances using a special mixture. During the manufacturing process or molding process of synthetic polymeric substances, these synthetic polymeric substances or their modified substances often adhere to these devices. As a result, in manufacturing equipment, a decrease in reaction volume or a decrease in reaction controllability due to a decrease in the heat transfer coefficient of the heat transfer surface due to deposits causes a decrease in productivity and hinders stable operation. Deterioration of product appearance and color may occur due to the contamination of some of the products. On the other hand, similar problems occur in molding equipment as well, such as in the operation of the equipment or in the quality of the product. Furthermore, flow paths in various devices often become narrowed or blocked by deposits. Various adhesion prevention methods have been proposed in the past to prevent such adhesion of synthetic polymer substances to equipment, etc., but none of these methods can be said to be perfect.
Depending on the method, it may even have a negative effect on the color, fluidity, and other qualities of the product. Therefore, the development of better methods for removing deposits remains an urgent and important issue. Conventionally, as a method for removing deposits, a method of dissolving them mainly using a solvent has been proposed. However, in the case of vinyl-based synthetic polymer materials,
Compared to ordinary polymeric substances, some kind of alteration (e.g. gelation) has occurred, or there is a special bonding state with the metal or glass surface to which it is attached, so it cannot be used with solvents. Removal of deposits is often incomplete. Therefore, when removal using solvents is not desirable, mechanical removal methods using hammers, grinders, drills, etc. are used, but these removal methods only require unnecessary manpower and work time. However, this is not a desirable method as it may cause damage to the equipment and contamination of the worker by residual chemical substances. As a result of various detailed studies on methods for removing synthetic polymeric substances using solutions, the present inventors have discovered an excellent adhesion method that could not be predicted from the conventional technique of removing synthetic polymeric substances using a solvent. We have discovered a combination of solvents that has the effect of removing kimono, and have completed the present invention. That is, the present invention provides cyanoolefins, acrylic esters, methacrylic esters,
Polymers of monomers belonging to vinyl aromatics and diolefins, or copolymers of two or more of these monomers, or 80 to 99.9 parts by weight of one or more of these monomers. , a benzene solvent, acetone, Aliphatic alcohols having 10 or less carbon atoms and 5 carbon atoms are added to 100 parts by weight of one or more solvents selected from ethyl methyl ketone, methyl propyl ketone, acrylonitrile, dimethyl formamide, tetrahydrofuran, dimethyl sulfoxide, and dioxane. This is a method for removing deposits from synthetic polymer substances, which comprises contacting with a mixture obtained by adding 100 parts by weight or less of a liquid consisting of one or more types selected from the following aliphatic glycols. According to the method of the present invention, cyanoolefins,
Polymers of monomers belonging to acrylic esters, methacrylic esters, vinyl aromatics, and diolefins, or copolymers of two or more of these monomers, or one or two of these monomers. A polymer that is a copolymer of 80 to 99.9 parts by weight of a specific type or more and 0.1 to 20 parts by weight of a vinyl monomer copolymerizable with these monomers and/or a monomer capable of ring-opening polymerization. Compared to conventional methods that use solvents or swelling agents to remove deposits, this method is extremely effective, but the reason for this is not clear.
However, a liquid consisting of one or more selected from benzene solvents, acetone, ethyl methyl ketone, methyl propyl ketone, acrylonitrile, dimethyl formamide, tetrahydrofuran, dimethyl sulfoxide, and dioxane may be used alone, or an alcohol having 10 or less carbon atoms and Considering the fact that the method of the present invention, which uses a mixture of the former and the latter, exhibits an extremely superior removal effect compared to using a liquid consisting of one or more types of glycols having carbon atoms of 5 or less alone. Therefore, it is considered that the effects of the present invention are derived from a combined effect due to the coexistence of both of the above liquids. Examples of vinyl-based synthetic polymer substances in the present invention include cyanoolefins such as acrylonitrile and methacrylonitrile; acrylic acid esters such as methyl acrylate and ethyl acrylate; such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, etc. methacrylic acid esters, such as styrene,
Polymers consisting of monomers belonging to vinyl aromatics such as α-methylstyrene, chlorostyrene, bromostyrene, and vinylnaphthalene, and diolefins such as butadiene, isoprene, and chlorobutadiene, or one or two of these monomers. A copolymer consisting of more than one type of monomer, or 80 to 100 parts by weight of one or more of these monomers, such as acrylic acid, methacrylic acid, and vinyl acetate that can be copolymerized with these monomers. It is a copolymer of 0 to 20 parts by weight of a vinyl monomer such as or/and a monomer capable of ring-opening polymerization, such as ethylene oxide or propylene oxide. Even when the above-mentioned mixing ratio exceeds 20 parts by weight, the effects of the present invention can be observed to some extent, but the degree of effect is reduced. The solvent used in the present invention may be one that dissolves or swells the synthetic polymer substances described above, and examples thereof include benzene-based solvents such as benzene, toluene, propylbenzene, xylene, ethylbenzene, and styrene, acetone, and ethyl benzene. Included are methyl ketone, methyl propyl ketone, acrylonitrile, dimethyl formamide, tetrahydrofuran, dimethyl sulfoxide, dioxane, and the like. The aliphatic alcohols having 10 or less carbon atoms in the present invention include all aliphatic alcohols having 10 or less carbon atoms, such as methanol, ethanol, propanols, butanols, pentanols, hexanols, etc. These can be used alone or as a mixture of two or more. If the number of carbon atoms exceeds 10, it is not practical because the viscosity increases or it solidifies at room temperature. The aliphatic glycols having 5 or less carbon atoms as used in the present invention include all aliphatic glycols having 5 or less carbon atoms, such as ethylene glycol, propylene glycol, and the like. Moreover, these can be used alone or as a mixed liquid of two or more. When the number of carbon atoms exceeds 5, it is not practical because the viscosity increases or solidification occurs at room temperature. The mixture referred to in the present invention is carbon based on 100 parts by weight of a liquid consisting of one or more of benzene solvent, acetone, ethyl methyl ketone, methyl propyl ketone, acrylonitrile, dimethyl formamide, tetrahydrofuran, dimethyl sulfoxide, and dioxane. Any mixture may be used as long as it is a mixture obtained by adding 100 parts by weight or less of a liquid consisting of one or more liquids selected from aliphatic alcohols having 10 or less carbon atoms and aliphatic glycols having 5 or less carbon atoms. If the amount of the liquid containing one or more of the above-mentioned alcohols and glycols exceeds 100 parts by weight, it is not preferable because the adhesion removal effect of the mixture decreases. It is also permissible to add other substances to the above mixture in acceptable amounts. For example, methylene chloride, raw material monomers, water, etc. may be added to the mixed solution of the present invention during operation in a factory, but it is sufficient if the amount is small. Moreover, it is also possible to add compounds such as surfactants to the liquid mixture of the present invention. In the present invention, the method of contacting the vinyl synthetic polymer substance deposit with the mixture includes, for example, in the case of a reaction tank, a method of filling the tank with a mixed solution and bringing the mixture into contact;
Alternatively, there is a method of spraying a mixed liquid onto the surface of the deposit using pressure. When removing deposits by filling the mixed liquid, it is preferable to use stirring and ultrasonic cleaning together. It is also possible to use the mixture of the present invention after previously removing some of the deposits using raw monomers or a suitable solvent. There is no particular limitation on the temperature at which the mixture is brought into contact with the vinyl-based synthetic polymer substance deposits referred to in the present invention, and can be appropriately selected depending on the workplace environment and the location of the deposits. However, temperatures near or above the glass transition temperature of the deposited synthetic polymeric material are preferred. As described in detail above, the method for removing vinyl-based synthetic polymer material deposits according to the present invention achieves an extremely superior removal effect compared to conventional removal methods, and also reduces the amount of labor and time required for removal. Since the amount of carbon dioxide is reduced, the economic benefit is large and its industrial utility value is enormous. Below, examples of the method according to the invention will be described. Examples 1 to 5 Composition: A 2 cm x 10 cm steel test piece was placed in a continuous bulk polymerization reaction tank of AS resin, which supplied raw materials with 70% by weight of styrene monomer and 30% by weight of acrylonitrile monomer, and continuous polymerization for one month was carried out. It was taken out after the production run. This test piece contains gel-like
AS resin was attached. Next, the mixture 1 of the present invention and the above test piece were placed in a flask having a volume of 2, and stirring was continued for 10 hours while refluxing at the boiling point of the mixture at normal pressure. The results of this deposit removal test are shown in Examples 1 to 5 in Table 1. Comparative Examples 1 to 3 Comparative Examples 1 to 3 in Table 1 show test results when a mixture of ethylbenzene, acrylonitrile, and toluene and ethanol was used instead of the mixture of the present invention used in Examples 1 to 5. .

【table】

[Table] Amount of deposits removed
(weight)
Deposit removal rate (%) =

Claims (1)

[Claims] 1 A polymer attached to the inner wall of a synthetic resin polymerization device or a molding device, which is a polymer of monomers belonging to cyanoolefins, acrylic esters, methacrylic esters, vinyl aromatics, and diolefins, Or a copolymer consisting of two or more of these monomers, or 80 to 99.9 parts by weight of one or more of these monomers,
When removing a copolymer with 0.1 to 20 parts by weight of a vinyl monomer copolymerizable with these monomers and/or a ring-opening polymerizable monomer, benzene solvent, acetone , ethyl methyl ketone,
For 100 parts by weight of one or more solvents selected from methylpropyl ketone, acrylonitrile, dimethylformamide, tetrahydrofuran, dimethyl sulfoxide and dioxane,
Aliphatic alcohols with carbon number of 10 or less and carbon number of 5
1. A method for removing deposits from synthetic polymer substances, which comprises contacting with a mixture obtained by adding 100 parts by weight or less of a liquid consisting of one or more selected from the following aliphatic glycols.