DE1301089C2 - PROCESS FOR THE PRODUCTION OF FIBER-FORMING ACRYLIC NITRILE / VINYL ACETATE MIXED POLYMERIZES - Google Patents

Description

The copolymerization of acrylonitrile and vinyl acetate using a combination of chlorate and sulfite or hydrosulfite ions as a Reclox catalyst is known and z. As described in the USA. Patents 2,673,192 and 2,751,374, where the molar ratio of chlorate to sulfite or hydrosulfite is substantially in the range of 1: 3 to I: 6 lies. In French patent specification 1,133,067, a ratio of 1: 3 is also given for the copolymerization of acrylonitrile and vinyl acetate.

According to US Pat. No. 3,028,371, the copolymerization of acrylonitrile and vinyl acetate To achieve a polymer with a high degree of whiteness, the molar ratio of sulfite to chlorate ions increased from at, for example 5: 1 to 10: 1. The polymerization takes place without the addition of a sulfonic acid Monomers, but the polymerization reaction is under the influence of reducing Sulfur dioxide gas carried out, the development of which through the use of a large excess of a Sulphite ion-evolving compound is effected. The polymerization time is for a batch process a total of 4 hours and is therefore rerht high.

The copolymerization of acrylonitrile and vinyl acetate in the presence of sulfite and chlorate has the A special feature is that the reaction rate, molecular weight and yield are low.

In the French patent ί 133 067 is in the copolymerization of acrylonitrile and methyl acrylate the addition of sodium methallyl sulfonate when using sulfite chlorate catalyst is shown, in order to obtain a very finely divided polymer. There are no statements about the rate of polymerization and molecular weight made, and indeed it has been found that when interpolymerized Acrylonitrile and methyl acrylate or methyl methacrylate neither chlorate / sulfite in the usual used ratios of 1: 3 to 1: 6 nor the addition of sodium methallyl sulfate any Effect on increasing the polymerization yield or on increasing the molecular weight exercise.

However, an increase in the molecular weight, the polymerization yield and the polymerization rate while maintaining a good degree of whiteness is technically highly desirable for the copolymerization of acrylonitrile and vinyl acetate.
There has now been a method of making

ίο fiber-forming acrylonitrile-vinyl acetate polymers by copolymerization of 86 to 95 percent by weight of acrylonitrile with 14 to 5 percent by weight of vinyl acetate in the presence of 0.02 to 3 percent by weight of the total monomers of an ethylenically unsaturated sulfonic acid or its water-soluble salt in an aqueous medium at temperatures of 20 to 70 ⁰ C and pH values of 1 to 6 in the presence of a redox Kalaiysators, which consists of chlorine ions and sulfite or hydrosulfite ions, found, in which this goal can be achieved if not less than 8 moles of a sulfite ion-yielding compound per mole of chlorate ions are used will.

Polyacrylonitriles produced in this way are very suitable for all purposes where a high molecular weight is essential, e.g. B. for fibers.

Preferably there are from S to 150 moles of a compound which provides sulfite ions per mole of chlorate ions used.

Unsaturated sulfonic acids which are added during the copolymerization are particularly suitable Allylsulfonic acid, methallylsulfuric acid, vinylbenzenesulfonic acid, Allyloxyäthylsulfonsäurc, Methallyloxyäthylsulfonsäure, Allyloxypropanolsulfonsäure, AlIyI-thicäthylsulfonsäure, Allylthiopropanolsulphonic acid, isopropenylbenzenesulphonic acid, vinylbromobenzenesulphonic acid, Vinyl fluorobenzenesulfonic acid and vinjlmethylbenzenesulfonic acid.

All water-soluble compounds can be used as compounds which provide chlorate, sulphite or hydrosulphite ions, for example chloric acid, water-soluble ammonium, alkali, alkaline earth and heavy metal chlorates as suppliers of chlorate ions, and sulfur dioxide, sulphurous acid, water-soluble ammonium, Alkali, alkaline earth and heavy metal sulfites, bisulfites, metabisulfites, hydrosulfites and thiosulfites as suppliers for sulfite and hydrosulfite ions. The amount of catalyst can vary over a wide range, but it is generally desirable to use about 0.01 to about ^{30 /} _a chlorate (as

chloric acid calculated), based on the weight of the monomeric mixture to be used.

It is surprising that the above-mentioned success does not occur if, instead of an unsaturated sulfonic acid or its salt, a saturated organic sulfonic acid having approximately the same number of carbon atoms as the unsaturated acid or its salt is added to the polymer medium.
Otherwise, however, the interpolymerization can be carried out in the usual way, as described, for example, in US Pat. Nos. 2,673,192 and 2,751,374. It can be carried out continuously or in batches. A particular advantage of the process of the invention, however, is that good yields and high molecular weight are achieved even when the process is carried out continuously with relatively short residence times of the monomeric mixture, which

13 Ol

is possible, as the following comparison shows.

Comparative experiments

In a flask equipped with a stirrer and a heating mantle at 45 C ^ü held Reaktionsfgß were continuously monomers Polymeri-Sä d W d

fgß w y

SrioBskatalysator, acid and water in the after specified proportions fed in, idk AliiVi

the reaction product, acrylonitrile-vinyl acetate-polymer, was continuously withdrawn, the residence time was 70 minutes. The Monomereeroisch contained 88 parts by weight of acrylonitrile and * parts by weight of vinyl acetate. The monomer mixture made up 28% of the total suspension introduced. Nairiumchlorat was added in an amount of 0.51 parts and 100 parts of the monomer mixture, jjjatriumsulfit was used in an amount of 3 moles per mole Katriumchlorat. Nitric acid was added to adjust the pH values given in Table 1. The average molecular weight in the yield of the polymers obtained is shown in Table 1, from which it can be clearly established that although the molecular weight is increased by adding sodium methallylsulfonate, the polymer yield (conversion) is not increased

Table 1

no increase in yield due to the addition of the metalallyl sulfonate.

However, it is also not sufficient to just increase the molar ratio of sulut / chlorate without using an ethylenically unsaturated sulphonic acid at the same time in order to achieve the desired purpose, as the following table 3 shows, where otherwise identical working conditions without sodium methallylsulphonate, but with a C1O ₃ / SO ₃ ratio of 1: 8 was worked.

Table 3

NaCIÜ. NaClO,: Na, SO ₃ pH Yield to
Copoly- By
cut Parts Molar ratio 2.75 merisat Molecular weight 0.33 1: 8 2.88 76.5% 612C0 0.30 1: 8 2.82 76.3% 67 OGO 0.29 1: 8 2.90 71.7% 67 300 0.27 1: 8 2.90 66.5% 66 900 0.24 1: 8 54.1% 64 600

Amount of sodium
mcihallyl sulfonate pH Polymer
healed average
liches mole Parts gross weight 100 parts of iMonomers each (%) 0 2.67 77.4 67 900 0.25 2.56 77.6 70 600 0.50 2.75 78.1 76 100 0.75 2.83 76.0 77 900 2.00 2.71 77.5 87 200

Then the same experiments were repeated with the exception that the catalyst composition, as indicated in Table 2, was varied. The results are shown in Table 2.

Tabel

NaClO ₃
Parts NaClO ₃ -. Na ₂ SO ₃
Mole ratio pH the end
prey average
good chance
kulaigcwicht 0.44
0.46
0.50 V ₃
V ₃
V ₃ 1.74
1.87
1.72 76.3
75.3
77.2 79 700
74 200
69,000

It can be seen that the molecular weight

even if the concentration of the polymerization catalyst is decreased, the bulge does not increase is even reduced.

So it's not just by varying the catalyst concentration possible, a copolymer

with a molecular weight greater than 70,000.

The behavior during the copolymerization of acrylonitrile and vinyl acetate is therefore in sharp focus In contrast to the behavior in the case of copolymerization

of acrylonitrile and methyl acrylate or methyl methacrylate, as the following table 4 shows, where again under otherwise identical conditions, monomer mixtures of 90.4 parts of acrylonitrile and 9.6 parts Methyl acrylate or from 91.2 parts of acrylonitrile and: nd

8.8 parts of methyl methacrylate with the addition of sodium methallyl sulfonate have been polymerized. It can be seen that the addition of sodium methallyl sulfonate no influence on the yield and the average molecular weight of the

has stood copolymer. The in table 4 The specified amount of sodium methallyl sulfonate is based on 100 parts of the monomeric mixture.

Table 4

55

From Table 2 above, it can be seen that as the amount of sodium chlorate increases, the molecular weight decreases but the yield (conversion) is not noticeably changed.

From the above two series of tests it can be seen that with a chlorate / sulfite molar ratio = V ₃ in the production of acrylonitrile-vinyl acetate copolymers, the molecular weight is increased by adding methallyl sulfonate. However, the yield remains practically unchanged within the range of 75 to 78%, and thus it is found

Together Amount of Mixed copoly By setting the Methallyl metisate cut monomers
mixture sulfonate yield Molecular weight AN-MA 0 77.5 75,000 AN-MA 0.25 78.0 73 500 AN-MA 0.50 77.6 76100 AN-MA 0.75 78.6 76 200 AN-MA 1.00 77.4 78 600 AN-MMA 0 76.0 72 900 AN-MMA 0.50 76.4 73 800 AN-MMA 1.00 76.2 73 300

AN = acrylonite MA = methyl acrylate MMA = methyl methacrylate

The molecular weights given in the preceding and following tables were determined according to the Staudinger equation, as described in U.S. Patent 2,404,727.

The following examples illustrate the invention.

example 1

A Reaktiousgefäß with a stirrer, which was kept by a mantle heater at 45 ⁰ C, was continuously fed with appropriate amounts of monomers Poiymeiisationsinitiator, acid and water, and d ^ s resulting reaction product was continuously withdrawn from the vessel. The monomer mixture used consisted of 88 parts of acrylonitrile and 12 parts of vinyl acetate, and the proportion of the monomer mixture was 28% of the total amount of the suspension introduced Sodium sulfite was 8 moles per mole of sodium chlorate. The amount of nitric acid added was adjusted so that the pH of the polymerization system was maintained in the range of 2.8 to 2.9. As shown in Table I, the polymerization reaction was carried out in the presence of various amounts of sodium methallylsulionic acid per 100 parts of the monomer mixture. It was found that when the amount of sodium methallylsulfonate was increased, the particle size of the resulting copolymer was reduced and the yield of the copolymer was increased and the end product had a high average molecular weight.

Table I.

Amount of
Methallyl sulfonate

0.25

0.25

0.50

0.75

2.00

Coarse distribution of the mixed polymers > 0.1 mm I η ι ■: * η ns mm I <°, 06 mm

9.6

5.8
0
0
0

Example 2

0.1 ils 0.06 mm (%)

44.5

32.0

42.5

24.1

2.7 polymer yield

66.5

Average molecular weight

66 900

70.1 70 500 72.2 76 200 73.9 79 400 74.2 93 300

A reaction vessel with a stirrer kept at 55 ° C. by means of a heating mantle was used continuously charged with monomers, polymerization initiator, acid and water in such a way that the average residence time was 75 minutes and the resulting reaction product became continuous withdrawn from the vessel. The monomer mixture used consisted of 86 parts of acrylonitrile and 14 parts of vinyl acetate, and the proportion of the monomer mixture was 28% of the total amount of the imported Suspension. Based on lÜO parts of Monomeie 0.27 parts of sodium chlorate were used, 5 moles of sodium sulfite being added per mole of sodium chlorate Became. Sulfuric acid became the reaction

system added so that the pH of the polymerization system was held in the range of 2.9 to 3.0. Table II shows the values that were obtained when the polymerization reaction with an alternating amount of sodium methallyl sulfonate and with a similarly changing amount of sodium butanesulfonate was carried out, which the sodium? alz a saturated sulfonic acid with the same number of carbons

atoms such as methallyl sulfonate. You can see it Table II that with a chlorate-sulfite ratio of 1: 8 the addition of sodium methallyl sulfonate, an ethylenically unsaturated sulfonic acid. as well as the yield as well as the average molecular weight of the final product increases, while the Addition of sodium butanesulfonate, i.e. a saturated sulfonic acid, no such acid at all Has effect.

Table II Type of sulfonic acid added

Amount of sulfonic acid (% of the monomers) copolymer yield

Average molecular weight

control

Sodium methallyl sulfonate
Sodium methallyl sulfonate
Sodium butanesulfonate ...
Sodium butanesulfonate, ..

0, A0

0.75

0.40

0.75 62.5
70.4
75.7
61.4
61.4

61200 71500 81300 60 300 61000

next the flask was deionized with 1400 parts

Example 3 Water, 90 parts of acrylonitrile, 10 parts of vinyl acetate

and a changing amount of a sulfonic acid

In a glass flask fitted with a stirrer, reflux connection (see Table III). After green cooler, With a thermometer, nitrogen gas inlet, and dropwise mixing, the suspension was funneled to 54 ° C Acrylonitrile was kept in each and the atmosphere in the top of the flask Approaches with vinyl acetate copolymerized to- replaced by nitrogen gas, whereupon 1.2 parts of nitric

13 Ol 089

nge
Hurry

'. in
at

ug ·
so
ns- / ie
on
ling
ng
nrt
Ie
: s

acid, 0.18 parts of sodium chlorate and 2.13 parts of sodium sulfite were added (molar ratio NaClO ₃ : Na ₂ SO ₃ = 1:10). The polymerization was continued for a predetermined time, then the polymerization suspension was filtered, washed with water, filtered off with suction and dried. In this way, copolymers were obtained, the yield and average molecular weight of which are shown in Table III. It can be seen from Table III that as the amount of potassium 4-vinylbenzenesulfonate, an unsaturated organic sulfonic acid, is increased. Yield and molecular weight of the resulting copolymer can also be increased, while the addition of p-toluenesulfonic acid, which is not considered to be unsaturated organic sulfonic acid, generally has no such effect.

Table III

A
set
Sulfonate Amount of
Sulfonate Polymeri
station
Time Poly
merisat
yield By
fast
Molecular weight (Parts) (Minutes) <%) none 0 30th 51.0 76,000 none 0 120 66.5 71 500 VBS 0.3 30th 47.1 87 300 VBS 0.3 120 M, 4 88 200 VBS 0.75 30th 63.4 127 ΟΠΟ VBS 0.75 120 75.8 112,000 VBS 1.00 30th 69.9 134,000 VBS 1.00 120 81.4 120,000 VBS 2.00 30th 67.4 169,000 VBS 2.00 120 89.4 122O0O PTS 0.50 30th 52.3 69,000 PTS 0.50 120 64.6 6S 300 PTS 0.75 30th 50.9 71 200 PTS 0.75 120 65.2 67 100 PTS 1.00 30th 26.8 75 500 PTS 1.00 120 35.9 64 600 PTS 2.00 30th 54.5 74 600 PTS 2.00 120 75.0 70 700

Vinyl acetate and 1.0 part of potassium-4-vinylbenzene sulfonai charged. After thoroughly mixing the stirring, the suspension was brought to 45 ° C and the atmosphere in the top of the flask was replaced with nitrogen gas. Then 2.02 parts of nitric acid, 0.17 part of sodium chloro ¹ and 5.57 parts of sodium dithionite were added (molar ratio NaClO ₃ : Na ₂ S ₂ O ₄ - 1:20). The polymerization reaction was allowed to proceed for 21 minutes. Arr

ίο at the end of this time the suspension was filtered, mi Washed with water, filtered off with suction and dried, 21.3 parts of a copolymer were obtained The average molecular weight of this polymer was 63,600. If, on the other hand, the polymer sation reaction under the same conditions as above, but in the absence of potassium-4-vinyl benzenesulfonate was carried out, the obtained Copolymer had an average molecular weight of 46,800 and the yield was 10.5 parts

VBS potassium-4-vinylbenzenesulfonate PTS - p-toluenesulfonic acid

Example 4

In one with stirrer, reflux condenser. Thermometer, nitrogen gas inlet and dropping funnel In the glass flask, acrylonitrile was copolymerized in batches with vinyl acetate. First was the piston with 1400 parts of water, 92 parts of acrylonitrile, 8 parts

Example 5

Acrylonitrile was copolymerized batchwise with vinyl acetate in a glass flask equipped with a stirrer, reflux condenser, thermometer SticksUwfgaseinlaß and dropping funnel. First the flask was charged with 1400 parts of water, 95 parts of acrylonitrile, Steiler vinyl acetate and 1.5 parts of potassium 4-vinylbenzenesulfonate. After thorough mixing: the stirrer set the suspension to 45 "C and the atmosphere in the top of the flask was replaced with nitrogen gas. Then 3.31 parts of nitric acid, 0.10 parts of sodium chlorate and 5.92 parts were added Sodium sulfite (molar ratio: NaClO ₃ : Na ₄ SO ₁ = 1:50) was added. The polymerization reaction was allowed to run for 120 minutes .9 parts of a copolymer: This copolymer had an average molecular weight of 67,000.

On the other hand, when the polymerization reaction is carried out under the same conditions as above was, but in the absence of potassium-4-vinyl benzenesulfonate, the resulting mixed ^ olymeri sat has an average molecular weight of 51200 and the yield was 21.1 parts. It can be seen from the above results that the addition of potassium 4-vinylbenzenesulfonate to the reaction system ii The presence of a 50-fold excess of sulfite ion affects the yield and average molecular weight weight of the resulting acrylonitrile-vinyl acetate-Co Polymer increases

409685/33)

Claims (2)

* Patent claims: 1. A process for the production of fiber-clad acrylonitrile-vinyl acetate mixed resins by copolymerization of 86 to 9: 5 percent by weight of acrylonitrile with 14 to 5 percent by weight of vinyl acetate in the presence of 0.02 to 3 percent by weight of the total monomers of an ethylenically unsaturated sulfonic acid or its water-soluble salt in an aqueous medium at temperatures from 20 to 70 ^° C. and pH values from 1 to 6 in the presence of a redox catalyst which consists of chlorate ions and sulfite or hydrosulfite ions, characterized in that not less than 8 mol of a compound which yields sulfite ions are used per mole of chlorate ions will. 2. The method according to claim 1, characterized in that the compound which develops sulfite ions is used in an amount of 8 to 150 mol per mole of chlorate ions.