DE2503453A1 - PROCESS FOR THE PRODUCTION OF POLYMERIZED VINYLESTERS - Google Patents

Description

PATENT LAWYERS

D! Pl.-ing. P. WlRTH Dr. V. SCHMIED-KOWARZIK Dlpl-lng. G. DANNENBERG Dr. RWElNHOLD Dr. D. GUDEL

28H34 β FRANKFURT / M.

TELEPHONE (0611) ^ _{7014 Ga} ESCHENHEIMER STB.39

Case; LP1114
wd / around

LONZA AG
Gampel / Wallis
(Management: Basel) Switzerland

Process for the preparation of polymers of vinyl esters

The invention relates to a process for the production of colorless copolymers of vinyl esters with 1 to 18 carbon atoms in the carboxylic acid residue, with ethylene and optionally other copolymerizable monomers by a redox polymerization process in emulsion with conversions of over 98%, based on the vinyl ester components.

It is known from British patent specification 931 628 to polymerize vinyl chloride by the emulsion polymerization process at temperatures below 0 ^° C. with a system of hydroperoxides, in particular cumene hydroperoxide, ascorbic acid and iron (II) salts. With this method, only low conversions of up to 75% are achieved. During the polymerization, crusts and precipitates are formed which do not ensure regular particle formation in the polymer.

According to "Die Makromolekulare Chemie" 95 (1966) p.190, Vi-

50983 1 / 082S

Polymerized nyl chloride at temperatures from 0 to -35 ° C with a system of hydrogen peroxide iron (III) sulfate / ascorbic acid. The resulting products have reduced molecular weights. . ''

According to German Offenlegungsschrift 1,940,095 vinyl chloride ions at temperatures below 0 ⁰ C to the dispersion process with a redox system peroxide / iron (II) / polymerized ascorbic acid. The polymers obtained are not very stable to heat, and the conversion achieved is low.

In the German Offenlegungsschrift 1.916.942 vinyl chloride is used using mixtures of organic hydroperoxides, polymerized organic sulfites, derivatives of organic sulfinic acids and alkali metal alcoholates. the The polymerization yield is only 20%.

According to the German Offenlegungsschrift 2.O5O.723 the disadvantages of the known methods are to be eliminated by vinyl chloride ions at temperatures from -10 to -40 ⁰ C with a system hydrogen peroxide, salts of organic sulphinic acids, Cu (II) and ethylenediaminetetraacetic acid is polymerized . But even with this method, only low sales are achieved.

All of these known processes for the polymerization of vinyl chloride at low temperatures there is the disadvantage that only low conversions are achieved. The further disadvantage is that the crust formation, ung and agglomeration

509831/0825

no morphologically uniform products can be achieved. The thermal and weather stability of these well-known products leaves much to be desired.

It is also known to prepare aqueous copolymer dispersions of vinyl ester and ethylene by the emulsion polymerization method in the presence of peroxidic compounds with or without the addition of reducing agents. It is often disclosed that the quality of the dispersions and the mechanical properties of the polymers can be improved by metering in one or more polymerization components. In British Patent 1,117,711, the ethylene pressure is kept constant during the polymerization. According to DAS 1.127.085, not only is additional ethylene added, but the catalyst is also continuously added during the polymerization. According to DAS 1.267.429, not only peroxides but also reducing agents are used, one of the two components being initially charged and the second being metered in with the vinyl ester. However, these processes produce polymers with a low molecular weight (Fikentscher index (K value) below 45), which have surface tackiness and tend to flow cold.

The disadvantage of all known processes is that they do not ensure a rapid and uniform course of the polymerization and, moreover, not too uniformly structured copolymers to lead. Furthermore, high catalyst concentrations are necessary in order to achieve useful conversions. Also have to Reserves of cooling and pressure capacities are kept free in order to absorb the reaction peaks that occur. This is

509831/0825

indicates that the cooling and pressure capacities of the polymerization reactors cannot be fully exploited. The remaining high residual monomer content is also disadvantageous. The high

Amounts of catalyst lead to reduced degrees of polymerization.

According to German Offenlegungsschrift 2.112.769, these disadvantages of the known processes are to be eliminated by placing the vinyl ester together with the reducing agent in the aqueous dispersing aid solution and adding the peroxide component in such a way that a constant polymerization temperature in the range of 0 is achieved using the cooling capacity of the reaction vessel - 10O ⁰ C is maintained.

However, this process is also not technically satisfactory, since conversions of only 70%, based on the vinyl ester, are obtained.

It has now been found that a redox polymerization process produce morphologically homogeneous copolymers of vinyl esters with ethylene in emulsion with high conversions can, which are colorless and whose thermal and weather stability are good, if very specific polymerization conditions be respected. In addition, under the conditions according to the invention, coagulate-free, non-sedimenting, Crust-free and skin-free products are created, the K values of which can be adjusted.

According to the invention this is achieved by the Polymerization at temperatures of 20-30 ° C with the help of a redox system, consisting of 0.05-0.5% by weight, based on the

$ 509831/082

Vinyl ester of an alkali or aramonium persulfate, 0.01 -

0.05 wt .-%, based on the vinyl ester, ascorbic acid and 10 to 30 ppm of an iron (II) salt, based on the vinyl ester, carried out at a starting pH of 3-4, the '* The main amount of persulfate is presented and the iron (II) salt and ascorbic acid are added in such a way that a preselected constant polymerization temperature (+, 1 ° C) results.

The appropriate temperature to be used is between 26 - 28 ° C. The temperature control is expediently automatic, with the addition of the iron (II) salt and the ascorbic acid and external cooling are coordinated with one another in order to maintain a preselected constant polymerisation temperature. door, which should only deviate by + 1 ° C during polymerisation.

The preferred persulfate is potassium persulfate, although sodium and ammonium persulfate can also be used . The preferred amounts are 0.1 to 0.4 wt. Of these, at least 5090 are presented and the remainder is metered in during or at the end of the reaction.

Ascorbic acid is preferably added in amounts of 0.02 to 0.04% together with emulsifiers and the iron (II) salt. The iron (II) salt used is primarily iron (II) sulfate in amounts of 10-20 ppm. In addition, other iron compounds and complexes can be used which are capable of releasing iron (II) ions under the given conditions, such as iron (1H) sulfate, iron (II) -

509831/0825

Chloride, iron salt of ethylenediaminetetraacetic acid or Ferrocene. If, as according to DOS 2.112.769, the reducing agent would be so ascorbic acid / Fe-II salt presented would be colored Products received.

The starting pH, which is between 3 and 4, preferably 3.5, is determined by means of non-falling inorganic or organic Acids, e.g. nitric acid, hydrochloric acid, formic acid, acetic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid etc. set. During the polymerization, the pH can change without adversely affecting the polymerization will.

According to the process of the invention, copolymers of vinyl esters and ethylene with a high ethylene content can be obtained. For example, with respect to an emulsion polymerization at high temperatures (50-80 ⁰ C), wherein one pressures from 45 to 50 atm is required to copolymerize to 20% ethylene, in the present case unter.Arbeitsdrücken of only 10 to 30 atm, preferably 20 .- 25 atmospheres, ethylene the same ethylene content can be achieved in the product. According to the process of the invention, the ethylene is preferably metered in under constant working pressure.

The vinyl esters are those with 1 to 18 carbon atoms in the carboxylic acid residue into consideration. Such are unbranched. Vinyl esters such as vinyl acetate, vinyl propionate, vinyl laurate, vinyl palmitate, also branched vinyl esters such as vinyl isobutyrate, viriyl pivalate, Vinyl cyclohexanate, vinyl benzoate, and vinyl esters of the versatic acid type.

509831/0825

According to the method of the present invention, it is possible To produce products with a desired K-value in a wide range, i.e. one has the possibility to adjust the K-value to be set according to the application, e.g. between 50 - 120. Included'' it is also possible to use polymers with such high K values, namely between 70 and 120, as obtained by conventional processes Emulsion polymerization with free radical initiation are not achievable, can be obtained. The measure to achieve of products with a defined K value lies in the fact that certain quantities of vinyl esters are submitted. The highest K values are achieved when almost all of the vinyl ester and the ethylene are put together under constant pressure are added with the other components of the redox system. . - The sketch shows the dependency of the K value on the one presented Amount of vinyl ester for certain test parameters (according to Examples 1-4) listed.

The products obtained by the process according to the invention are characterized by an increased thermal stability, a improved weather resistance and increased alkali resistance.

In addition to vinyl esters and ethylene, other copolymerizable ones can also be used Monomers are polymerized, are expedient

such monomers are used in amounts of 1-80% by weight , based on the vinyl esters. Such copolymerizable monomers are, for example, olefins such as propylene, 1-butylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid and fumaric acid and the esters of all mentioned

509831/0825

Carboxylic acids and the mono- and diesters of all mentioned dicar-, ' bonic acids, preferably the esters which contain 1-18 carbon atoms in the alcohol component, such as methanol, Ethanol, propanol, butanol, isobutanol, ethylhexanol, lauryl alcohol; unsaturated ethers, such as alkyl vinyl ethers, e.g. methyl, ethyl, butyl, isobutyl, lauryl, stearyl vinyl ethers, isopropenylmethyl or ethyl ether, vinyl halides such as vinyl chloride, carboxamides of unsaturated acids such as methacrylamide, N-methylol acrylamide, maleimide and allyl type unsaturated compounds.

The per se known anionic and nonionic wetting agents, expediently in amounts of 0.05-5% by weight , based on the vinyl esters, can be used as emulsifiers. Suitable anionic emulsifiers are alkyl sulfates, sulfates of alkyl and Alkylarylp olyäthoxyalkanolen, Alkylsulfonate, Alkylaryl-

sulfonates and esters of sulfosuccinic acid with alkanols. Suitable non-ionic emulsifiers are, for example, addition products of ethylene and / or propylene oxide with alkanols, with alkylphenols, with carboxylic acids and block copolymers of propylene oxide with ethylene oxide. The polymerization can be carried out in the presence or absence of colloids. Examples of colloid formers include polyvinyl alcohol and water-soluble modifications thereof; water-soluble cellulose derivatives, such as hydroxyethyl, hydroxypropyl, methyl, ethyl, carboxymethyl cellulose;

water-soluble polysaccharides and derivatives thereof; Polyacrylic acid and water-soluble derivatives thereof; expedient to

$ 509831/082

8%, for use.

The well-known polymerization regulators such as aldehydes, saturated ■ or unsaturated halogenated hydrocarbons and mercaptans

can also be used.

General polymerization processes

In a stirred autoclave with a given capacity, with temperature control, The solution of the components of the aqueous phase (water, emulsifiers, Potassium persulfate, possibly colloid). To Flushing with nitrogen, a certain amount of vinyl ester is added, and ethylene is applied up to a certain pressure and set the desired temperature (26 - 28 ° C). To- The metering in of the ascorbic acid together with the iron (II) salt, dissolved in water, begins until the start of the polymerization. At the moment when a sudden rise in temperature from 1 - 2 ° C is observed, the metering rate of the reducing agent, utilizing the cooling capacity of the reaction vessel, regulated. At the same time, the feed of the remaining monomers can be adjusted to the feed rate of the reducing agent can be matched. The ethylene pressure is kept constant during the polymerization. The polymerization takes between 4 and 12 hours, depending on the cooling capacity.

Example 1) · '

This general procedure is used in a 2 liter stirred autoclave the following approach polymerizes:

509831/0825

a) aqueous phase:

deionized water 500 g

Antarox Co 63O ^ (Nonylphenol poly-

ethylene oxycondensate) 2 g

Potassium persulfate 2 g <:

Glacial acetic acid (pH regulator: 3.5) Ig

Polyvinyl alcohol)

88% saponified. Viscosity of a) 25 g

4% solution at 20 °: 25 cp)

b) reducing agent solution:

• deionized water 100 g

Iron (II) sulfate (Fe.SO47H ₂ O). 0.01 g

Antarox Co 63O ^ 4 g

Ascorbic acid 0.4 g

c) Vinyl acetate (VA) total 500 g

of which as a template

(2O% of the total VA amount) 100 g

Polymerization temperature 27 ° C

Reaction time. · 5 hours

Ethylene pressure = working pressure 24 atm

Example 2)

In accordance with Example 1), a series of pus was used Tests carried out, the conditions according to Table I) - varying. In Table 2) are the properties of the obtained Products listed. It can clearly be seen from this that in .. the Examples 1-4, according to the invention, the required Properties were achieved. In Examples 5-7, the conversions are low and the products become colored obtain. The storage stability and the behavior of the dispersion towards fillers were in experiments 1 4 very good. In contrast, the storage stability of the products from experiments 5-7 was poor (sedimentation).

509831/8825

Tabel

(Examples 1-7)

Example no. 1 2 3 4th 5 * 6 * 7 * Glacial acetic acid (% on VA) 0.2 0.2 0.2 0.2 0.2 0.2 Ascorbic acid {% on VA) 0.08 0.03 0.04 0.08 0.2 0.2 0.08 Potassium persulfate (% of VA) 0.4 0.4 0.4 0.4 1.2 1.2 ■ 1.2 VA submitted)
% of the total) 20th 10 5 100 20th 20th 20th Polymerization) 27 27 28 26-28 35o36 26-40 26th temperature ⁰ C) Reaction time (minutes) 240 250 300 220 200 190 200 Ethylene pressure (atu) '24 24 24 24 24 Ik 24

* Examples not according to the invention

Table 2 (general properties of the products)

Example no. 1 2 3 4th 5 * 6 * 7 * % Turnover (on VA) 98.9 99.4 99.4 98.5 95.4 90.5 94.5 K value (from Fikontscher "J 103.7 97.6 86.5 118.2 90.9 78.7 70 Ethylene content in)
Copolymer) 18th 18.5 21 14.5 16 13th 16 Brookfield visco-)
sity of the disp. "*) Poises
(50% dry matter) 110 160 210 65 40 25th 90 Appearance of the dispersion
Appearance of the film not
colored
clear
not
colored not
colored
clear
not
colored not ■
colored
clear
not
colored not
colored
clear
not
colored colored
easy
colored colored
strong
colored
some
grain g colored
easy
colored

* Examples not according to the invention

** the Fikentscher index is calculated on the basis of the relative Viscosity of a solution of 1 g of polymer in 100 cm3 of dimethylformamide

*** Brookfield viscosity measured with measuring body 6 at IO tours, minute

509831/0825

Example 8)

It was as in Example 1) but with a monomer composition of 425 g VA and 75 g vinyl chloride instead of 500 g VA worked. A terpolymer dispersion VA / VC / Ethylene with a conversion over 98%, the composition of which is:

VA 75% Ethylene 14% VC 11% Filcentrian Index 83.5 Example 9)

As Example 1), but with a monomer composition of 400 g VA and 100 g maleic acid dibutyl ester gave a terpolymer dispersion VA / DBM / ethylene ,, (conversion over 98%) with 15% ethylene content in the copolymer and a Fikentscher index of 81.

Example 10) ■

Like example X) ,. but with 15 g hydroxyethyl cellulose (Natrosol 250 MR) instead of polyvinyl alcohol, a dispersion with a conversion of 99% was obtained. The ethylene content of the copolymer was 19%, the Filcent's index was 99.

Example 11)

As Example 1), but with a monomer composition of 400 g of VA and 100 g of ethyl acrylate were at a conversion of 98.1%, a dispersion in which the ethylene content (in the copolymer ) / ν was 12%. The Fikentscher Index was 79.

509831 / Q825

Example 12)

You work as in example 1), but with the following components:

a) aqueous phase: Pluronic F 68® Pluronic L 62® sodium lauryl sulfate Acrylic acid)

. . ,. ,. * pH regulator sodium bicarbonate) * water

b) Reducing agent solution: deionized water Ascorbic acid

. Iron (II) sulfate

c) monomer mixture: VA Monomer Pluronic F 62® (dissolved in the monomer) Monomer initial 20% of the total

Polymerization temperature, reaction time, ethylene pressure

A very fine one was obtained with a conversion of over 99% Dispersion (<0.2 μm), the polymer of which contained 22% ethylene and a Fikentscher index of 95.1. -

Example 13)

The procedure is as indicated in Example 12), with the exception that part of the water in the template (100 g) is used to dissolve " of 15 g of methyl acrylamide was used and this solution

16 G Hours. 5 G atü 2.5 G 2 G 1 G 450 G 100 G 0.4 G 0.01 G 500 G 7th G 100 G 26 ° C 4th 24

was introduced into the reaction medium at the same time with metering in of the reducing agent and the remaining monomers. After 5 hours of reaction, a fine dispersion (as in Example 12) with a conversion of over 98% was obtained, the ethylene content of the polymer being 16% and its Fikentscher index being 73. This dispersion can be in the presence of 0.2% oxalic acid, can be converted by treatment for 3 minutes at 15O ° C _r in a crosslinked and insoluble film. The films of these polymers produced according to the invention have excellent heat resistance and very good mechanical properties. Their elongation at break is between 600 and 1000% with a corresponding tensile strength between 120 and 60 Kp / cm2.

As shown in Example 13), it is possible to copolymerize a very reactive crosslinking monomer, without the risk of crosslinking during the polymerization.

503831/0826

Claims (1)

- 15 patent claims 1.) Process for the preparation of copolymers of vinyl esters with 1 to 18 carbon atoms in the carboxylic acid radical, with ethylene and optionally other copolymerizable monomers by a redox polymerization process in emulsion with conversions of over 98%, based on the vinyl ester components in that the polymerization is carried out at temperatures of 20 to 3O ⁰ C with the aid of a redox system consisting of 0.05 to 0.5 wt .-%, based on the Vinylester, an alkali metal or ammonium persulfate, from 0.01 to 0, 05% by weight of ascorbic acid, based on the vinyl esters, and 10 to 30 ppm iron (II) salt, based on the vinyl esters, at a starting pH of 3 to 4, the majority of the persulfate being initially charged and the iron (II) salt and the ascorbic acid are metered in so that a preselected constant polymerization temperature (+ 1 ° C) results. 2.) Method according to claim 1, characterized in that the rate of polymerization is controlled via the dosage of the reducing initiator components so that a constant polymerization temperature (+ 1 ° C) is maintained. . .. 509831/0825 5 · 'The method according to claim 1-2, characterized in that "by choosing the ratio between the initially charged and metered amount of vinyl esters the K value (Fikentscher index) of the! product is set will. 4.) Method according to claim t1i ^. "3 _f " _: ->. "characterized in that the ethylene is metered in under a constant working pressure of 10-30 atmospheres, preferably 20-25 atmospheres. 509831/0825