KR100574132B1 - Purification means - Google Patents

Abstract

Polymers containing 4-alkoxystyrene are purified by slurrying this polymer many times in methanol.

Description

Purification method {PURIFICATION MEANS}             

When isolated from the reaction solution, copolymers and terpolymers are mixtures of compounds having various compositions and molecular weights. Typically, they contain small amounts of undesirable by-products and starting materials in the final polymer. The polymer mixture is precipitated from the solvent or solvent mixture by adding a non-solvent such as water, hexane, heptane, octane, petroleum ether or mixtures thereof to the mixture. The polymer is then dried in air or nitrogen atmosphere. The present invention relates to a method for purifying a polymer.

Davidson, US Pat. No. 5,945,251, discloses polyhydrides by adding amines, hydrophilic solvents, hydrophobic solvents and water to the polymer, then separating the aqueous phase and then removing the hydrophilic and hydrophobic solvents to form a purified polymer. A method for purifying oxystyrene polymers is disclosed.

Zempini et al., US Pat. No. 5,789,522 and US Pat. No. 5,939,511 disclose the extraction of impurities from phenolic resins by dissolving phenolic resins in a photoresist solvent and extracting water soluble impurities therefrom. Doing.

Summary of the Invention

The present invention provides a novel method of improving the glass transition temperature of polymerized polymer intermediates by precipitation from methanol. Polymers which can be treated by the process of the present invention include polymers of 4-alkoxystyrene. The 4-alkoxystyrene polymer is then hydrolyzed or transesterified with 4-hydroxystyrene-containing polymers useful in paints, resins, thickeners and light resistant compositions. The present invention is an improvement over the prior art and is quite effective. Specifically, the present invention provides a method for removing unreacted monomers, low molecular weight polymers, and the like from the crude polymer mixture. Many analytical methods can be used to quantify the improvement in the purity of the polymer. Average molecular weight, nuclear magnetic resonance, chromatography and glass transition temperature are all effective in certain cases involving certain molecules and characteristic side chains.

As described above, the crude polymer after polymerization is separated from the alcohol using filtration, centrifugation, decantation, and the like. According to the process of the invention, the polymer is reslurried in methanol and the solids are separated from methanol. This process is repeated as long as it is necessary to remove low molecular weight substances and by-products that are more soluble in methanol than the desired polymer.

The present invention is a homopolymer, a polymer selected from the group consisting of: And / or acrylate monomers and / or styrenes, 4-methylstyrene, tert-butylstyrene, cyclohexyl acrylate, tert-butyl acrylate, tert-butyl Provided are methods for improving the composition of polymers of at least one ethylenically unsaturated copolymerizable monomer selected from the group consisting typically of methacrylate, maleic anhydride, dialkyl maleate, dialkyl fumarate, vinyl chloride, and the like,

The polymer provides only monomers of the formula (I) below in suitable polymerization conditions for a time sufficient to produce a polymer of the corresponding composition at a suitable temperature in the presence of a free radical initiator in an alcoholic solvent, or a monomer of the formula (I) and / or It is typically prepared by applying the monomer of formula II and / or one or more of the aforementioned copolymerizable monomers:

Where

(i) R ¹ and R ² may be the same or different and independently

Hydrogen,

Fluorine, chlorine and bromine,

Alkyl having 1 to 4 carbon atoms and the general formula C _n H _x F _y , wherein n is an integer from 1 to 4, x and y are integers from 0 to 2n + 1, and the sum of x and y is 2n + 1 Fluoroalkyl group, and

Phenyl and tolyl
It is selected from the group consisting of;

(ii) R ³ is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl and tert-butyl;

(iii) R ⁴ is selected from the group consisting of methyl, ethyl, n-propyl, iso-propyl and tert-butyl;

(iv) R ⁵ is methyl or ethyl.

After purification by the process of the invention, the purified polymer is (1) a transesterified byproduct ester formed by applying the polymer to transesterification conditions in the alcoholic solvent in the presence of a catalytic amount of base catalyst at a suitable temperature. Is continuously removed from the reaction mixture to form a homopolymer of the monomer of formula (I) or a copolymer of the monomer of formula (I), the monomer of formula (II) and the copolymerizable monomer, or (2) the polymer for acidic hydrolysis with strong acid. By application is hydrolyzed or transesterified with a polymer containing the monomer of formula III:

The polymer is then optionally passed through an ion exchange bed to remove the base or acid catalyst:

The alcohol solvent for the polymerization is an alcohol having 1 to 4 carbon atoms and is selected from the group consisting of methanol, ethanol, propanol, isopropanol, tert-butanol and mixtures thereof. The amount of solvent used is not critical and can be any amount that achieves the desired end result.

Free radical initiators for polymerization can be any initiator that achieves the desired end result. Initiators include 2,2'-azobis (2,4-dimethylpentanenitrile), 2,2'-azobis (2-methylpropanenitrile), 2,2'-azobis (2-methylbutanenitrile), 1 , 1'-azobis (cyclohexanecarbonitrile), tert-butyl peroxy-2-ethylhesanoate, tert-butyl peroxy pivalate, tert-amyl peroxy pivalate, diisononanoyl per Oxide, decanoyl peroxide, succinic peroxide, di (n-propyl) peroxydicarbonate, di (secondary-butyl) peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, tert-butylperoxyneo It may also be selected from the group consisting of decanoate, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, tert-amylperoxy neodecanoate and mixtures thereof.

The initiator is typically 2,2'-azobis (2,4-dimethylpentanenitrile), 2,2'-azobis (2-methylpropanenitrile), 2,2'azobis (2-methylbutanenitrile) , 1,1'-azobis (cyclohexanecarbonitrile), tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxy pivalate, tert-amyl peroxy pivalate and mixtures thereof It is selected from the group consisting of.

The polymerization conditions are not critical and can be any temperature and pressure at which the desired final product can be prepared. Generally, the temperature is about 30 ° C. to about 100 ° C., preferably about 40 ° C. to about 100 ° C., and most preferably about 45 ° C. to about 90 ° C. The pressure may be at atmospheric pressure, below atmospheric pressure or above atmospheric pressure. The polymerization time is not critical but is generally carried out for a time of at least one minute to prepare a polymer of the corresponding composition.

In the first stage transesterification, the crude polymer of stage (a) is subjected to said transesterification conditions in an alcoholic solvent in the presence of the catalytic amount of the base catalyst. The base catalyst is one that does not substantially react with the alkyl acrylate monomer of Formula II or the copolymerizable monomer. Base catalysts are alkali metal hydroxides or alkali metal alkoxides. Base catalysts include lithium hydroxide, lithium methoxide, lithium ethoxide, lithium isopropoxide, sodium hydroxide, sodium methoxide, sodium ethoxide, sodium isopropoxide, potassium hydroxide, potassium methoxide, Potassium ethoxide, potassium isopropoxide, cesium hydroxide, cesium methoxide, cesium ethoxide, cesium isopropoxide and mixtures thereof.

If hydrolysis is used to remove phenolic blockers, the acid should be a type of strong acid, for example hydrochloric acid, hydrobromic acid, sulfuric acid, or the like.

According to the process of the invention, the polymerization of the alkoxystyrene-containing polymer is completed and prior to hydrolysis or transesterification, the crude polymer is slurried in methanol. The slurry is then vigorously stirred or heated to boiling for a few minutes and then left to cool or cooled. The purified polymer is removed by centrifugation, filtration, decantation or similar method, and a small sample of methanol removed by decantation, e.g. by decantation, is removed until no further purification is required. Repeat until no display at all.

This example illustrates the use of the method of the present invention for purifying a copolymer of 4-acetoxystyrene / 3-butyl acrylate. 3282.8 g of 4-acetoxystyrene and 254 g of tert-butyl acrylate were polymerized in 3140 g of methanol using 204.3 g of tert-butyl peroxypivalate as catalyst. Polymer samples were isolated for analysis purposes. After completion of the polymerization, 1390 g of methanol was removed at 58 ° C. and replaced with 1392 g of fresh methanol. The slurry was heated to reflux and cooled to 48 ° C. A further 1595 g of methanol was removed and replaced with 1590 g of fresh methanol. The slurry was then heated to reflux and cooled. Methanol was removed, replaced with 1800 g fresh methanol, and the mixture was then transesterified with 39.8 g sodium methoxide.

Claims (1)

Alkoxystyrene-containing crude polymers selected from the group consisting of: And / or acrylate monomers and / or styrenes, 4-methylstyrene, tert-butylstyrene, cyclohexyl acrylate, tert-butyl acrylate, tert-butyl A method for purifying an alkoxystyrene-containing crude polymer of at least one ethylenically unsaturated copolymerizable monomer selected from the group consisting of methacrylate, maleic anhydride, dialkyl maleate, dialkyl fumarate and vinyl chloride, A process for slurrying the polymer in methanol, heating or stirring the obtained slurry and removing methanol to provide a purified product: Formula I

Formula II

Where (i) R ¹ and R ² may be the same or different and independently Hydrogen, Fluorine, chlorine and bromine, Alkyl having 1 to 4 carbon atoms and the general formula C _n H _x F _y , wherein n is an integer from 1 to 4, x and y are integers from 0 to 2n + 1, and the sum of x and y is 2n + 1 Fluoroalkyl group, and Phenyl and tolyl It is selected from the group consisting of; (ii) R ³ is selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl and tert-butyl; (iii) R ⁴ is selected from the group consisting of methyl, ethyl, n-propyl, iso-propyl and tert-butyl; (iv) R ⁵ is methyl or ethyl.