Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymerizing in reactor of specified material – or in reactor...
Reexamination Certificate
1993-04-09
2001-09-18
Henderson, Christopher (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymerizing in reactor of specified material, or in reactor...
C526S065000, C526S344000, C528S147000, C528S150000, C528S153000, C528S154000, C528S155000
Reexamination Certificate
active
06291600
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved method of monopolymerizing or copolymerizing vinyl chloride, and more particularly a method of preventing the polymer from adhering to the inner wall surface of a polymerization tank and the like at the time of polymerization. Further, the present invention also relates to a coating agent for preventing a polymer from adhering to the inner wall surface of a polymerization tank and the like and to a method of producing said coating agent.
2. Prior Art
Vinyl chloride is polymerized alone or copolymerized (hereinafter simply referred to as “polymerized”) with a monomer copolymerizable with it. However, the polymer adheres to apparatus parts that are in contact with the monomer(s) during the polymerization such as a polymerization tank inner wall, reflux condenser, stirring blades, baffles, and various attached pipeline connecting parts, there arise such problems that the cooling capability of the polymerization tank decreases or the polymer adheres to the apparatus parts and then break off to go into the homopolymer or copolymer (hereinafter referred to as “product”) of vinyl chloride thereby lowering the quality of the product. Therefore, customarily, every time after the completion of polymerization, the inside of the polymerization tank is cleaned and then polymerization is effected, but to do so needs much labor and time, which leads to the reduction of the operating efficiency of the polymerization tank and the increase of the production costs.
Accordingly, hitherto, techniques have been suggested wherein an agent is applied to the inner wall of a polymerization tank and other parts to prevent a polymer from adhering thereto.
However, although these techniques are effective for preventing a polymer from adhering, they are accompanied by such defects that the polymerization rate is lowered and physical properties of the product are deteriorated and therefore they are not satisfactory to be used industrially. Further, although techniques that do not influence adversely the polymerization rate and physical properties of the product are suggested, the techniques are not so much effective for preventing a polymer from adhering. For example, although techniques wherein a co-condensate of resorcin and an aldehyde is applied (JP-A (“JP-A” means unexamined published Japanese patent application) Nos. 502169/1982 and 502170/1982) are suggested, the effect for preventing a polymer from adhering is still not adequate.
OBJECTS OF THE INVENTION
A principal object of the present invention is to provide a method of preventing effectively a polymer from adhering to the inner wall surface of a polymerization tank and the like at the time of homopolymerization or copolymerization of vinyl chloride.
Another object of the present invention is to provide a coating agent for preventing a polymer from adhering to the inner wall surface of a polymerization tank and the like.
Still another object of the present invention is to provide a method of producing a coating agent for preventing adhesion.
SUMMARY OF THE INVENTION
In one mode of the present invention, a coating agent to be applied to a polymerization tank inner wall and apparatus parts that will be in contact with a monomer(s) during the polymerization comprises an aqueous solution adjusted to a pH at which a specific condensation product that dissolves at a certain pH value, i.e., at temperatures at the time of the application deposits, when the aqueous solution is heated, on the polymerization tank inner wall and the like. When such a coating agent is used, the polymerization tank inner wall and the like are covered with a thin film uniformly and firmly and an excellent effect of preventing a polymer from adhering can be obtained.
In another embodiment of the present invention, a coating agent is provided that has an effect of preventing a polymer from adhering to a polymerization tank inner wall and the like. A typical example of the coating agent is a solution containing a modified condensate of a phenol and an aldehyde.
In a preferable embodiment of the present invention, a method of polymerizing vinyl chloride according to the present invention comprises applying a reaction product having a molecular weight of 500 to 100,000 to a polymerization tank inner wall and apparatus parts that will be in contact with the monomer(s) during the polymerization at the time when the vinyl chloride is polymerized in an aqueous medium or is subjected to mass polymerization, which reaction product is previously obtained by condensing a dihydroxybiphenyl and an aldehyde in the presence of an acid catalyst.
In another embodiment of the present invention, a coating agent to be applied to a polymerization tank inner wall and apparatus parts that will be in contact with a monomer(s) during the polymerization is a co-condensate obtained by reacting an initial condensate of a phenol and an aldehyde with compounds including at least a hindered phenol.
In still another embodiment of the present invention, a coating agent to be applied to a polymerization tank inner wall and apparatus parts that will be in contact with a monomer(s) during the polymerization is an aqueous alkali solution containing a co-condensate with phenolic hydroxyl groups, the pH at which the co-condensate deposits from the solution being 8.0 or over and the water-solubility of the co-condensate being 35% or below.
Preferably, said co-condensate is one having a weight-average molecular weight of 500 to 10,000 obtained by reacting an initial condensate of a phenol and an aldehyde with a hindered phenol and a poly-valent phenol in the presence of a strongly acidic catalyst.
According to still another embodiment of the present invention, a method of producing a coating agent for preventing vinyl chloride polymer from adhering to the inner wall surface of a polymerization tank and the like where vinyl chloride is polymerized is provided.
Further, the present invention provides a method of producing a coating agent to be applied to a polymerization tank inner wall and apparatus parts that will be in contact with a monomer(s) during the polymerization. That is, the method comprises a step of producing an initial condensate of a phenol and an aldehyde, a step of producing a modified phenolic resin by reacting the obtained initial condensate with a hindered phenol, a nitrogen-containing compound, or a poly-valent phenol, a step of diluting the reaction product liquid containing the modified phenolic resin with water, a step of adjusting the pH of the diluted liquid to deposit the modified phenolic resin, and a step of dissolving the deposited modified phenolic resin in an organic solvent or an aqueous alkali solution.
REFERENCES:
patent: 4200712 (1980-04-01), Cohen
patent: 4320215 (1982-03-01), Tonezawa
patent: 4355141 (1982-10-01), Okada
patent: 4431783 (1984-02-01), Walker
patent: 4555555 (1985-11-01), Toyooka
patent: 4579758 (1986-04-01), Dorsch
patent: 54-107991 (1979-08-01), None
patent: 55-160004 (1980-12-01), None
patent: 58-180511 (1983-10-01), None
patent: 61-181802 (1986-08-01), None
Fukuda Keiichi
Hatakeyama Yasuyuki
Masuko Seiichi
Naka Yoshimatsu
Nakamura Ichisaburo
Burns Doane Swecker & Mathis L.L.P.
Henderson Christopher
Mitsui Chemicals Inc.
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