JP3053212B2 - How to prevent polymerization reactor scale. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to U.S. patent application Ser.
No. 213,743, which is a continuation-in-part application of US Pat.
July 26, 1988 based on U.S. Pat. No. 4,853,446.
Derived from PCT Application No.
It is a continuation-in-part of U.S. Patent Application No. 344,169, filed February 16, 1989.

BACKGROUND AND DISCLOSURE OF THE INVENTION Field of the Invention U.S. Pat.Nos. 4,853,446 and 4,855,424 disclose novel compounds and compositions that have been found to prevent scale from sticking to the walls of vinyl chloride polymerization reactors. . The scale of such a reactor impedes heat transfer and consumes expensive monomers that are not end products, thereby increasing the amount of waste that must be disposed of safely.

The aforementioned patents disclose the use of the additives of the present invention in various polymerization reactions to produce polyvinyl chloride, including emulsion, bulk, suspension and microsuspension polymerizations.

A pending patent application filed on the same day as this patent application, Case 6
No. 143 discloses the use of the compounds and compositions disclosed in the aforementioned patents in a microsuspension process in which the polymerization is carried out in a tubular reaction zone without stirring. The disclosure of the pending patent application is incorporated herein by reference. The latter microsuspension method is disclosed in U.S. Pat.
No. 2, No. 4,528,337 and No. 4,528,227, the contents of which are referenced. In this method,
The tubular reactor extends preferentially in the axial direction and is preferably substantially circular in cross section.

It is an object of the present invention to provide an improved process for the polymerization of polyvinyl chloride using certain phenothiazine derivatives to reduce reactor wall fouling or scale buildup during the polymerization of vinyl chloride and comonomer, as well as aggregated material. That is.

Prior Art U.S. Pat. No. 2,415,252 describes the preparation of phenothiazine derivatives by reacting phenothiazine with formaldehyde and alcohol under conditions that produce modified phenothiazines having a methylene or alkoxy group attached. The compounds and their oil solutions are said to be pharmaceutically, veterinary and useful for controlling plague.

U.S. Pat. No. 2,528,092 describes the reaction of phenothiazine with formaldehyde and N-dimethylaniline. The resulting compounds are useful as antioxidants in mineral oil lubricants.

U.S. Pat. No. 4,465,881 describes N, N'-dimers of phenothiazine or substituted phenothiazines. This compound is obtained by linking two phenothiazine molecules by their N groups. These dimers are
Prepared by heating phenothiazine in the presence of an organic peroxide. These dimers are disclosed as being useful in stabilizing vinyl aromatic compounds such as styrene and substituted styrene against unwanted polymerization.

U.S. Pat.No. 4,529,500 discloses N, N'-phenothiazine or substituted phenothiazines for protecting hydrocarbon processing equipment against fouling during hydrocarbon processing at elevated temperatures.
The use of dimers is disclosed.

By Romanovich and co-workers,
Published in SSR, Chemical Abstracts 98: 144251d
Report the reaction of phenothiazine with formaldehyde under conditions favorable for the production of cured products. The reaction appears to take place at the nitrogen group of the phenothiazine, resulting in the formation of relatively high molecular weight crosslinked products.

In U.S. Pat. No. 4,229,510, a polymeric material is formed from a substituted phenothiazine having an alkyl substituent attached to the nitrogen group. The reaction with formaldehyde appears to take place between the phenyl group and formaldehyde. The resulting product has a nitrogen group protected by the starting alkyl group. The resulting product is reported to have photoconductivity.

U.S. Pat. No. 4,565,834 describes compounds having the chemical formula of a dimer or polymer of phenothiazine. The patentee's compositions are useful as stabilizer-containing reactive components in the production of polyurethane foams with little or no tendency to core decolorization.

SUMMARY OF THE INVENTION The object of the present invention is to formula: (Wherein R is -CH ₃ or It is. ) Carrying out the polymerization in the presence of a compound having
It is accomplished by providing a polymerization method for polymerizing vinyl chloride and comonomers to polyvinyl chloride and copolymers.

The object of the invention is also the formula: (Wherein, n is an average value of from about 1 to about 5, R is -CH ₃
Or It is. ) Wherein n is an average value from about 1 to about 5. wherein the polymerization is carried out in the presence of a composition having the formula:
It is accomplished by providing a polymerization method for polymerizing vinyl chloride and comonomers to polyvinyl chloride and copolymers.

The polymerization method of the present invention includes emulsion polymerization, bulk polymerization, suspension polymerization and microsuspension polymerization.

The present invention also includes a method of reacting a selected aldehyde, such as acetaldehyde and benzaldehyde, with phenothiazine.

The present invention further includes a method of reacting a substituted phenothiazine with formaldehyde. A suitable substituted phenothiazine is acetylphenothiazine.

In the foregoing method, the phenothiazine is reacted with the aldehyde in the presence of a liquid diluent that is a solvent for the phenothiazine but not a dimer of the phenothiazine and aldehyde and a higher oligomer of the phenothiazine and aldehyde.

These reactions are generally performed in the presence of a strong acid catalyst. The aldehyde is slowly added to the reaction mixture during the course of the reaction. The product can be filtered and dried.

Embodiments of the Invention The present invention has the formula: And a reaction product of phenothiazine which is a compound having This compound is currently used in the control of animal plague, for example in pharmaceutical applications against pinworms in animals.

2-acetylphenothiazine: Are also useful in preparing the compounds and compositions of the present invention.

In preparing the compositions of the present invention, phenothiazine is reacted with an aldehyde. The molar ratio of aldehyde to phenothiazine is generally about 0.1 to 1, preferably about 0.4 to 1, and more preferably about 0.5.

The diluent for the reaction mixture of the present invention is a liquid that dissolves phenothiazine, but is not a solvent for the dimer of phenothiazine and aldehyde and the higher oligomeric phenothiazine and aldehyde. Thus, as dimers and higher oligomers of phenothiazine are formed during the course of the reaction, such dimers and higher oligomers can precipitate from the diluent and be removed from the reaction mixture.

Suitable diluents include non-polar solvents such as tetrahydrofuran (THF), dimethylformamide (DMF), cyclohexanone and dimethylsulfoxide (DMSO).

Suitable polar diluents include alcohol. Although higher alcohols with up to 10 carbon atoms can be used,
Alcohols having 1 to 5 carbon atoms are preferred.
Suitable alcohols include methanol, ethanol, n-
Includes propanol, isopropanol, n-butanol, secondary butanol, isobutanol and tert-butanol.

Although polar solvents are preferred for the reaction of the present invention, mixtures of polar and non-polar solvents have been found to be suitable for dissolving the monomers but also performing the function of precipitating dimers and higher oligomers. When a mixture is used, the weight ratio of non-polar solvent to polar solvent is generally about 0.1 to 10, preferably about 0.5 to 2, and more preferably about 1 to 1. It has been found that the solubility function is important for determining the structure of the product of the invention. Therefore, if a too effective solvent is used,
Dimers and higher oligomers do not precipitate and the molecular weight is too high. On the other hand, when the function of the solvent is insufficient, the monomer dissolves and it becomes difficult to use the solvent for reaction with formaldehyde to obtain a reaction product.

The diluent is used in the reaction mixture such that the phenothiazine is present from about 1 or 2 to about 25%, preferably up to about 10%, by weight of the diluent. The reaction product should be sufficiently diluted so that it can be filtered to remove solvent from the product.

As a catalyst for the reaction, an acidic compound or an alkaline compound can be used. However, acid compounds are preferred,
Among them, strong acids are more preferred. Preferred compounds include hydrochloric, sulfuric, nitric and phosphoric acids. Suitable caustic compounds include sodium hydroxide and other alkali metal hydroxides.

In the process of the present invention, the aldehyde is slowly added to the mixture of diluent and phenothiazine so that they react orderly to form dimers and higher oligomers,
Dimers and oligomers precipitate from the reaction mixture.

Preferred reaction temperatures are from room temperature to the reflux temperature of the lowest boiling diluent, preferably about 60-80 ° C.

The reaction mixture is removed from the reaction vessel and filtered by conventional methods. Suitable filter media include paper and cloth such as nylon.

The filtered product is dried at a temperature between room temperature and the melting point of the composition of the present invention, preferably at a temperature of about 50-100 ° C.

The reaction product of the present invention generally comprises a mixture of the following components.

Component weight% phenothiazine monomer 1-10 dimer 70-85 trimer 5-15 higher oligomer 5-10 The reaction product generally has the formula: (Wherein R is -CH ₃ or And n is an average value of about 1 to about 5, preferably 1 to about 2, and more preferably 1 to about 1.5. ). The composition comprises a mixture of individual compounds having the formula where n is an integer from 1 to about 10, preferably from 1 to about 5.

Alternatively, the reaction product has the formula: (Where n is an average value of about 1 to about 5, preferably 1 to about 2, and more preferably 1 to about 1.5). The composition comprises a mixture of individual compounds having the formula where n is an integer from 1 to about 10, preferably 1 to about 5.

The reaction mixture can be processed to change the relative proportions of the aforementioned components. Thus, removing unreacted monomer from the reaction mixture by methanol extraction can reduce the proportion of unreacted monomer to about 0.5% by weight or less.

Dimers can be isolated from trimer and higher oligomeric materials by a series of extractions with suitable solvents.

Conversion of phenothiazines to dimeric and higher oligomeric materials is generally about 75-90%.

The dimer and the reaction product containing the dimer of the present invention are used to reduce or remove scale and agglomerated substances in components such as a reaction vessel and a stirrer used for polymerization of vinyl chloride, as described below. Used for The compositions of the present invention are also useful for the polymerization of vinyl chloride with an α-olefinically unsaturated comonomer, especially an ethylenically unsaturated comonomer, containing up to about 80 mol%, especially up to about 40 mol, of the comonomer. Such comonomers include vinyl acetate and other ethylenically unsaturated monomers known to those skilled in the art.

The dimer, alone or with higher oligomers, can be used in a suitable solvent such as tetrahydrofuran (THF) for about 0.3 to about 1
It is dissolved in a percentage by weight. The resulting solution is then brushed or sprayed on the reactor walls, on the reactor agitator, and inside the reactor head. The polymerization reaction mixture is prevented from forming undesirable scale on the reactor components. Other solvents that can be used in the solution applied to the reactor components include dimethylformamide (DMF), cyclohexanone and dimethylsulfoxide (DMSO).

The compositions of the present invention are also added directly to the polymerization reaction mixture, generally at a rate of about 0.0001 to about 0.1% solids, preferably about 0.001% solids, by weight of vinyl chloride and comonomer. You can also. The compositions of the present invention can be added to the polymerization zone as a dry solid or as a solution in the aforementioned solvents. The composition can also be added during the manufacturing process in the form of a wet cake after filtration but before drying.

The dimer, or reaction product containing the dimer, of the present invention is also useful for inhibiting the polymerization of monomers such as vinyl chloride or terminating the polymerization of such monomers.

Examples In the following examples and the specification, unless otherwise indicated, parts are parts by weight and temperatures are in ° C.

Example 1 (a) 10.0 g of phenothiazine was stirred with 50 cc of 95% isopropanol while adding 4.0 cc of concentrated HCl and 1.5 cc of acetaldehyde. The mixture was heated to reflux with stirring for 2 hours and filtered while hot on a Buchner funnel. The filter cake was washed with hot isopropanol to remove unreacted phenothiazine, then with a dilute solution of ammonium hydroxide to remove residual HCl and dried at 60 ° C. The tan powder is dissolved in tetrahydrofuran,
The infrared curve showed a strong secondary amine band and a 1,2,4-trisubstituted benzene ring band. This result indicates that acetaldehyde reacted only with the benzene ring.

(B) A microsuspension polymerization of PVC, known to deposit a lot of scale on the reactor, was carried out at 55 ° C. A 1% by weight solution of the product prepared according to Example 1 in tetrahydrofuran was applied to the stirrer. The following polymerization blend was used.

g Vinyl chloride 400 Deionized water 370 Sodium lauryl sulphate 4.0 Mixed fatty alcohol 5.0 Lauroyl peroxide 0.2 Homogenize the formulation at low pressure for 2 1/2 minutes before polymerization to provide conditions for large scale deposition in the reactor did.

 Control polymerization was performed without any application to the stirrer.

8.0 g of scale adhered to all surfaces of the control reactor
The amount of the aggregated substance was 5.0 g. The amount of scale adhered in the reactor having the stirrer applied was 1.2 g and the amount of aggregated substance was 0.9 g.

Example 2 (a) 10.0 g of 2-acetylphenothiazine was stirred with 50 cc of 95% isopropanol while adding 4.0 cc of concentrated HCl and 2.5 cc of 37% formaldehyde. The mixture was refluxed for 2 hours with stirring and then filtered while hot on a Buchner funnel. The cake was washed with hot isopropanol to remove unreacted starting material, then washed with dilute ammonium hydroxide to remove residual HCl and dried at 60 ° C. The yellow powder dissolves in tetrahydrofuran,
It showed an infrared spectrum similar to that of the product of Example 1. This result indicates that formaldehyde reacted only with the benzene ring.

(B) Using a formulation and method identical to that described in Example 1 (b), apply a 1% by weight solution of the product prepared according to Example 2 (a) in tetrahydrofuran to a stirrer. To carry out microsuspension polymerization of PVC.

The amount of scale adhered to the entire surface of the reactor having the stirrer applied was 0.1 g, and the amount of aggregated substance was 1.0 g.

Example 3 (a) 10.0 g of phenothiazine was stirred with 50 cc of 95% isopropanol while adding 4.0 g of concentrated HCl and 3.6 cc of benzaldehyde. While stirring the mixture, 2
Heated to reflux for hours and filtered while hot on a Buchner funnel. Unreacted benzaldehyde and phenothiazine were removed by washing with filtered isopropanol, and then washed with isopropanol containing ammonium hydroxide to neutralize residual HCl. The gray / green powder showed both a secondary amine band and a trisubstituted benzene ring band in the infrared curve.

(B) This material was added to the polymerization formulation used in Example 2 for 1
2.5 ppm (based on the weight of vinyl chloride) was added. 1.2 g of scale attached to metal surface and glass balls
The amount of the aggregated substance was 0.9 g.

Example 4 (a) Example 2 was repeated using diphenylamine instead of 2-acetylphenothiazine.

(B) When a 1% tetrahydrofuran solution of the reaction product was applied to a stirrer and polymerization was carried out according to Example 3,
The amount of scale attached on the metal surface and on the glass ball was 3.8 g, and the amount of aggregated substance was 4.3 g.

Example 5 (a) Example 2 was repeated using a tertiary amine compound, N-methylphenothiazine, and formaldehyde.

(B) When a 1% tetrahydrofuran solution of the reaction product was applied to a stirrer and polymerization was carried out according to Example 1,
The amount of scale attached on the metal surface and on the glass ball was 10.1 g, and the amount of agglomerated material was 4.3 g. This result shows that when no secondary amine is used, the phenothiazine derivative
Figure 3 shows the production of a product that forms a reactor scale and agglomerates in amounts comparable to the control polymerization not applied to the stirrer.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hong Paul O. USA 19087 Wayne Treaty Drive 63 (56) References JP-A-52-12291 (JP, A) JP-A-63-264611 (JP, A) Patent 2680394 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 2/00

Claims (4)

(57) [Claims] 1. A process for polymerizing vinyl chloride monomer and any ethylenically unsaturated comonomer in a proportion of up to about 80 mol%, based on the total monomer content, comprising the formula: (Wherein R is -CH ₃ or It is. ) Or An improved method comprising carrying out polymerization in the presence of a compound which substantially suppresses the adhesion of scale consisting of a phenothiazine derivative. 2. A process for the polymerization of vinyl chloride monomer and any ethylenically unsaturated comonomer in a proportion of up to about 80 mol%, based on the total monomer content, comprising the formula: (Wherein, n is an average value of from about 1 to about 5, R is -CH ₃
Or It is. ) Or Wherein n is an average value of about 1 to about 5. An improved method comprising conducting the polymerization in the presence of a composition that inhibits the adhesion of scale substantially consisting of a phenothiazine derivative. 3. A method according to claim 2, wherein the solution of the composition is applied to the walls of the polymerization zone. 4. The method of claim 2 wherein said composition is added to the polymerization at a solids level of from about 0.0001 to about 0.01% by weight based on the weight of vinyl chloride and comonomer.