Coating processes – Pretreatment – per se – or post-treatment – per se
Patent
1998-01-22
1999-03-30
Lusignan, Michael
Coating processes
Pretreatment, per se, or post-treatment, per se
524541, 526 62, B05D 300, C08F 200
Patent
active
058885897
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
My invention relates to a procedure for the anti-scaler production for coating the polymerizing reactors and respective product.
Anti-scaling agents for polymerizing reactors are already well known in prior art.
BACKGROUND ART
At the present state of the art there are also different types of anti-scalers for each type of polymer.
For example the anti-scaler for the production of vinyl chloride is not the same as that used in the reactor for the production of polystyrene or of that for the production of acrylic polymers, and so on.
This fact necessitates in the storing of different products with all the consequences of high management costs.
Additionally even the reactors must be specifically dedicated to only one reaction type, resulting in the increase of costs.
DISCLOSURE OF INVENTION
A first aim of this invention is that to make an anti-scaler that operates well in any type of polymerizing reactor and for the most varied types of different materials, therefore for vinyl chloride, as well as for styrene and acrylic polymers, etc.
In the specific case of vinyl chloride for example, it is known that in the reactors a substantial deposit of scale forms having as main drawbacks: interruption of the production, opening of the reactor and therefore high quantities of gaseous vinyl monomer chloride (VCM) immissions into the atmosphere; respective polymerized product with consequent worsening in quality and complaints of the users; problems for the areas in which the industrial polyvinylchloride plants (P.V.C.) operates.
This problem practically exists for all types of polymerizations.
Furthermore the anti-scaling products destined to coat the surfaces of the respective reactors are of a bluish colour or dark brown nearly black, wherefore the particles that detach from the crust, pollute the obtained polymer (for example obtained polyvinyl chloride) from the reactor under the form of black dots, that for example in the finished products worsens the qualitative aspect of the same product.
Furthermore it is to be noted that the material particles that detach from the crust of the wall, end up in the product in reaction, constituting the pollution of the same, dealing generally with toxic products.
In prior art, the technique of condensation or from polycondensation of naphthols with a aldehydic cross-linking product (eg., formaldehyde and others), to obtain anti-scaling products is known.
For this purpose one refers to:
U.S. Pat. No. 3,669,946 (filed in the U.S. on Aug. 31st, 1970, disclosed on Jun. 13th, 1972), that suggests the use of formaldehyde and ketonic composites, naphthol etc. and also alpha-naphthylamine and nigrosin. This teaching predivulges the general concept of forming condensate anti-scalers parting from the formaldehyde and naphthols combination.
U.S. Pat. No. 3,825,434 (23rd Jul. 1974) describes an anti-scaling agent for the polymerizing of vinyl chloride, obtained from the condensation of the phenol with formaldehyde, where obviously for definition in this patent the obtained product is always classified as pertinent to the phenol-formaldehyde or poliarilphenol family.
U.S. Pat. No. 4,068,059 (filed on 17 Feb., 1977; published on the 10 Jan. 1978) explains furthermore the importance of using as anti-scalers, products that in their chemicals structure contain one or more of the following groups: --OH; --COOH; SO3H and SO3Na.
EP-A-0052421 describes a process for obtaining an anti-scaling product that differs for the fact that the formaldehyde is made to react with 1-naphthol (alpha-naphthol), in which both the nuclear positions 2 and 4 are not replaced and the nuclear position 3 is not replaced or has a substitute that is not strongly electron-attractor to obtain a condensate.
It is also opportune to note that the use of the naphthols is already suggested from the U.S. Pat. No. 3,669,946, therefore it was obvious to use 1-naphthol in the preceding process in place of the phenols as mentioned.
Even in this case the product obtained according to the chemistry is to be conside
REFERENCES:
patent: 3669946 (1972-06-01), Koyanagi et al.
patent: 3825434 (1974-07-01), Berens et al.
patent: 4068059 (1978-01-01), Witenhafer
Database "Chemical Abstracts" Abs 120; 108 067, Columbus, Ohio & JP,A, 05 230 112 (Shinetsu Chem. Ind. Co., Sep. 1993.
Carlin Francesco
Sattin Mario
C.I.R.S. S.p.A.
Lusignan Michael
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