Process for the controlled alcoholysis of ethylene-vinyl ester interpolymers

Claim 2

In a process for the alcoholysis of an ethylene-vinyl ester interpolymer in a reaction medium comprising as components thereof said polymer, a low-boiling alcohol, a hydrocarbon solvent in an amount up to 1,000 parts by weight per part of the alcohol and an alkaline or acidic catalyst, wherein the aggregate initial amount of water contained in the polymer, the alcohol, the hydrocarbon solvent and the catalyst prior to the alcoholysis reaction is no more than 10% of the total weight thereof; the improvement comprising regulating the aggregate water content of said components introduced into a single alcoholysis reaction and into successive, otherwise identical alcoholysis reaction runs as not to vary by more than 50% by weight of said aggregate water content thereof, maintaining the reaction medium throughout the reaction and throughout successive reaction runs under a dry, inert atmosphere and otherwise carrying out the alcoholysis under conditions preventing the addition or loss of substantial quantities of water to or from said medium, to obtain a partially hydrolyzed polymer having a predetermined residual vinyl ester content.

Claim 3

The process of claim 1, wherein the ethylene-vinyl acetate interpolymer alcoholyzed contains from 3 to 57 mole percent of the vinyl ester, the balance of the interpolymer substantially comprising ethylene units.

Claim 4

The process of claim 1, wherein the ethylene-vinyl ester interpolymer alcoholyzed contains from 3 to 30 mole percent of the vinyl ester, and the aggregate initial water content of the components of the reaction medium, of any incremental portions of said components introduced during the reaction, and of the components introduced in successive reaction runs, is so regulated as not to vary by more than 20% of the initial water content thereof.

Claim 5

The process of claim 1, in which the partially hydrolyzed interpolymer is extracted with water to remove said low-boiling alcohol, the ester by-product of said alcohol, and catalyst residues; and is thereafter steam distilled in the presence of a surfactant to remove hydrocarbon solvent to produce an aqueous suspension of the partially hydrolyzed interpolymer in particulate form.

Claim 6

The process of claim 4, wherein the surfactant is a non-ionic ethylene oxide/propylene oxide block copolymer.

Claim 7

The process of claim 1, in which the partially hydrolyzed interpolymer is extracted with water to remove said low-boiling alcohol, the ester by-product of said alcohol, and catalyst residues; and is thereafter evaporated to produce the desired partially hydrolyzed interpolymer.

Claim 8

The process of claim 1, in which the partially hydrolyzed interpolymer is recovered by contacting the reaction mixture with an additional amount of said low-boiling alcohol under non-turbulent conditions, permitting the mixture to stand without applied agitation for a predetermined period, and thereafter agitating the mixture to precipitate the partially hydrolyzed produced as a rubbery crumb.

Claim 9

The process of claim 1, in which the partially hydrolyzed interpolymer contains less than 25% by weight of residual ester and in which the partially hydrolyzed product is recovered by adding an additional amount of said low-boiling alcohol to the reaction mixture at reflux, the product precipitating in finely divided particulate form.

Claim 10

The process of claim 1, in which the ethylene-vinyl acetate resin to be hydrolyzed contains more than 60% by weight of vinyl acetate and in which the partially hydrolyzed product is recovered by adding an additional amount of said low-boiling alcohol in admixture with water to the reaction mixture at reflux, cooling the reaction mixture and adding additional water, the product precipitating in finely divided particulate form.

Claim 11

The process of claim 1, in which the ethylene-vinyl acetate resin to be hydrolyzed contains more than 60% by weight of vinyl acetate and in which the partially hydrolyzed product is recovered by adding an additional amount of said low-boiling alcohol in admixture with acetone to the reaction mixture to precipitate the product in finely divided particulate form.

Claim 12

The process of claim 1, in which the hydrocarbon solvent is a linear or branched paraffin, a cycloaliphatic hydrocarbon, or an aromatic hydrocarbon; the low-boiling alcohol is a monohydric alcohol having from one to four carbon atoms; and the catalyst is an alkali metal or alkaline earth metal alkoxide whose alkanolic moiety corresponds to that of said low-boiling alcohol, an alkali metal or alkaline earth metal hydroxide; or a strong mineral or organic acid.

Claim 13

The process of claim 1, wherein the ethylene-vinyl ester interpolymer: catalyst weight ratio varies from 10,000:1 to 1:1, the hydrocarbon solvent: low-boiling alcohol weight ratio varies from 1:50 to 1000:1, the weight ratio of said interpolymer to the liquid mixture of said hydrocarbon solvent and low-boiling alcohol varies from 1:1000 to 100:1.

Claim 14

A process for the alcoholysis of an ethylene-vinyl ester interpolymer containing at least 20% of the vinyl ester, which comprises: a. reacting the interpolymer with a low-boiling alcohol in the proportion of from 100 to 150 percent of the molar quantity of said alcohol required for stoichiometric hydrolysis of the ester groups to be converted to hydroxyl groups on said interpolymer; b. introducing the reactants into a reaction zone in admixture with a hydrocarbon solvent in the proportion to said alcohol of from 1:50 to 1000:1 parts by weight, an alkaline or acidic catalyst in a molar ratio of from 1:20 to 1:5 parts per part of the alcohol, and water, the aggregate amount of water initially present in the components of the resulting reaction mixture being up to 5% by weight thereof; c. regulating the water content of the alcohol and hydrocarbon solvent introduced into said reaction medium throughout the reaction and throughout successive reaction runs as not to vary by more than 50% of the initial water content thereof; and d. maintaining the reaction medium in a dry, inert atmosphere; to thereby obtain a partially hydrolyzed ethylene-vinyl ester interpolymer having a predetermined residual vinyl ester content.

Claim 15

A process for the alcoholysis of an ethylene-vinyl ester interpolymer containing at least 20% of the vinyl ester, which comprises: a. reacting the interpolymer with a low-boiling alcohol in the proportion of from 100 to 150 percent of the molar quantity of said alcohol required for stoichiometric hydrolysis of the ester groups to be converted to hydroxyl groups on said interpolymer; b. introducing the reactants into a reaction zone in admixture with a hydrocarbon solvent in the proportion to said alcohol of from 1:50 to 1000:1 parts by weight, an alkaline or acidic catalyst in a molar ratio of from 1:20 to 1:5 parts per part of the alcohol, and water, the aggregate amount of water initially present in the components of the resulting reaction mixture being up to 5% by weight thereof; c. regulating the water content of the alcohol and hydrocarbon solvent introduced into said reaction medium throughout the reaction and throughout successive reaction runs as not to vary by more than 50% of the initial water content thereof; and d. maintaining the reaction medium in a dry, inert atmosphere; to thereby obtain a partially hydrolyzed ethylene-vinyl ester interpolymer having a predetermined residual vinyl ester content.

Claim 16

In a process for the alcoholysis of an ethylene-vinyl acetate copolymer containing at least 20% vinyl acetate in the presence of an alkaline or acidic catalyst and in a liquid reaction medium comprising a low-boiling alcohol and a hydrocarbon solvent in an amount of from 0 up to 1000 parts by weight per part of the alcohol, wherein the total initial water content of the alcohol, hydrocarbon solvent, copolymer and catalyst introduced is no more than 5% by weight thereof, the improvement comprising: a. regulating the aggregate water content of the alcohol and hydrocarbon solvent introduced throughout the reaction and throughout successive idential reaction runs within 20% of the aggregate initial water content thereof; b. maintaining the amount of the low-boiling alcohol in the reaction medium at 100-110% of the molar quantity required for stoichiometric hydrolysis of the acetate groups on said copolymer; and c. maintaining the reaction medium in a dry, inert atmosphere; to thereby obtain a partially hydrolyzed ethylene-vinyl acetate copolymer having a predetermined residual vinyl acetate content.

Claim 17

In a process for the alcoholysis of an ethylene-vinyl acetate copolymer containing at least 20% vinyl acetate in the presence of an alkaline or acidic catalyst and in a liquid reaction medium comprising a low-boiling alcohol and a hydrocarbon solvent in an amount of from 0 up to 1000 parts by weight per part of the alcohol, wherein the total initial water content of the alcohol, hydrocarbon solvent, copolymer and catalyst introduced is no more than 5% by weight thereof, the improvement comprising: a. regulating the aggregate water content of the alcohol and hydrocarbon solvent introduced throughout the reaction and throughout successive idential reaction runs within 20% of the aggregate initial water content thereof; b. maintaining the amount of the low-boiling alcohol in the reaction medium at 100-110% of the molar quantity required for stoichiometric hydrolysis of the acetate groups on said copolymer; and c. maintaining the reaction medium in a dry, inert atmosphere; to thereby obtain a partially hydrolyzed ethylene-vinyl acetate copolymer having a predetermined residual vinyl acetate content.

Claim 18

The process of claim 14, in which the hydrocarbon solvent is a linear or branched paraffin, a cycloaliphatic hydrocarbon, or an aromatic hydrocarbon; the low-boiling alcohol is a monohydric alcohol having from one to four carbon atoms; and the catalyst is an alkali metal or alkaline earth metal alkoxide whose alkanolic moiety corresponds to that of said low-boiling alcohol, an alkali metal or alkaline earth metal hydroxide, or a strong mineral or organic acid.

Claim 19

The process of claim 14, wherein the ethylene-vinyl ester interpolymer: catalyst weight ratio varies from 10,000:1 to 1:1, the hydrocarbon solvent: low-boiling alcohol weight ratio varies from 1:50 to 1000:1, the weight ratio of said interpolymer to the liquid mixture of said hydrocarbon solvent and low-boiling alcohol varies from 1:1000 to 100:1, and the total initial water level of the components of the reaction mixture varies from 0.005% to 0.5% by weight thereof.