DE1816782C2 - Process for the copolymerization of (1,3) butadiene with styrene or acrylonitrile in an aqueous emulsion - Google Patents

Description

Processes for the production of synthetic rubbers by copolymerizing butadiene- (13) with styrene or acrylonitrile in an aqueous emulsion in the presence of catalysts which generate free radicals are already known. For such processes, the alkali soaps and other water-soluble soaps of disproportionated natural resins, alone or mixed with fatty acid series, are usually used as emulsifiers (see. Whitby, "Synthetic Rubber", 1954 edition, pages 6, 7 and 217, where standard recipes are described in which these or other similar emulsifying agents can be used). The catalysts used in these processes include, for example, the peroxide catalysts potassium persulphate, hydrogen peroxide and cumene hydroperoxide and redox systems, for example those made from ferrous sulphate and sodium formaldehyde sulfate in combination with menihan hydroperoxide. In these known processes, modifying agents such as dodecyl mercaptan and electrolytes such as sodium phosphates can also be present.
Emulsion polymerization processes of this type are seldom carried out to completion. Rather, the polymerization is usually carried out so that 60 to 70% of the monomers are polymerized, whereupon the polymerization is quickly stopped and the reactor is unloaded and refilled with fresh emulsion. Under these circumstances it is difficult or impossible to prevent small amounts of oxygen from entering the reactor. In many cases, the polymerization must therefore be carried out in the presence of oxygen. This is very unfavorable since free oxygen extends the induction time of most of the polymerization systems described above and can greatly reduce the daily throughput of the plant.

From DD-PS 55 138 a process for the copolymerization of butadiene (1,3) with styrene or acrylonitrile in aqueous emulsion known to reduce the difficulty related to premature coagulation of the rubber a stabilized resin is used as an emulsifier, which is obtained by distillation of disproportionated natural resins under reduced pressure and transferring the overhead reaction or their Mixture with the residue fraction in the sodium or potassium soaps had been obtained.

In this process, too, the induction time is unavoidable due to the inevitably entering the reactor small amounts of oxygen, which is very unfavorable.

The object of the invention was therefore to provide a process for the copolymerization of butadiene (1,3) with styrene or To work out acrylonitrile in aqueous emulsion, with which these disadvantages of the known processes or can be overcome to a considerable extent.

Surprisingly, it has now been found that this adverse effect of oxygen can be eliminated or to a considerable extent overcome if a new class of disproportionated resin soaps is contained in the polymerization system. This resin soaps are alkali metal, ammonium and amine salts of disproportionation -3 tioniertem natural resin, the long by 1 to 18 hours of heating was modified to 250 to 300 ⁰ C.

The subject of the invention is thus the method described in the claim.

It is a significant advantage of the process of the invention that emulsions made with the new soaps of heat-modified disproportionated natural resin are produced, the adverse effect of free Tolerate oxygen during polymerization better than comparable emulsions made with other emulsifying agents are made. Another and probably more important advantage, however, is that the new emulsions obtained with heat-modified disproportionated natural resins independently whether air penetrates or not, polymerize faster under comparable polymerization conditions than emulsions made with other emulsifiers. In addition to their unusual property that they are the In other words, the new natural resin soaps also promote the adverse effects of oxygen Rate of polymerization.

Another important feature of the invention is its application to tall oil resin. Soaps of disproportionate Tall oil resins are technically used in recipes for synthetic rubber, for example in recipes for Butadiene-styrene rubbers, applied with roughly the same results as those with disproportionated Tree sap can be obtained. However, it has now been found that particularly good results are achieved when disproportionated tall oil resins are thermally modified and then converted into water-soluble soaps. With Much improved rates of polymerization are obtained from these soaps when used as emulsifying agents be used for emulsion polymerizations with free radicals. For example, through presence from 1 to 8% of the potassium soaps of any of the new resins described below in StyiOl-butadiene emulsion polymerization systems a reduction in the time it takes to achieve a conversion of 60 to 70% at 5 ° C is required to achieve 20 to 30%.

To produce the new resin soaps used in the process of the invention, disproportionated natural resin is subjected to a heat treatment at a temperature of at least 250 ^° C. to 300 ^° C., preferably from 260 to 300 ^° C., at atmospheric pressure. Disproportionated natural resin is a natural resin in which two hydrogen atoms from the acids of the abietic acid type with two double bonds under rearrangement and

Formation of an aromatic ring have been removed. This term is used herein to denote a natural resin used in which the abietic acid content in this way to less than 5% and preferably no more than 1%. In the art, this is done by heating the natural resin in the presence of a Disproporfionierungskatalysators, for example of iodine, sulfur or palladium or platinum, achieved, as it is in US Pat. No. 2,138,183. Reference is also made to US Pat. No. 2,479,226, in which the disproportionation reaction is applied to tall oil and alkali salts of the product for butadiene-styrene polymerizations be used.

To produce the soaps used in the process according to the invention, the new heat-modified soaps Natural resins, the disproportionated natural resin is kept at a temperature between 250 to 300 ° C until the product has a faster rate after converting it to its sodium soap, potassium soap, or other alkali soap Conversion of a butadiene-styrene emulsion into synthetic rubber shows in comparison to a soap des same, not heat-treated natural resin. A measurable improvement is seen after heating for one hour achieved at these temperatures After 2 hours the properties of the resin are considerably improved, however, when heating to temperatures of 250-270 ° C, it is advisable to keep heating up to 12-18 Hours to continue. In contrast, it runs at higher temperatures, and especially in the range from 290 to 300 "C, the modification is considerably faster, and the desired improvement can be achieved in 1 to 6 hours achieve. Temperatures up to 300 ° C can be used in conjunction with short times of 1 to 2 hours however, care must be taken to avoid excessive decarboxylation of the natural resin will.

The heat modification takes place at atmospheric pressure under a protective atmosphere of nitrogen or another inert gas.

The conversion of the heat-modified natural resins into their alkali, ammonium or amine soaps, e.g. B. the Sodium, potassium and morpholine salts can be obtained by reacting the resin with aqueous solutions from Hydro-Jf xides or carbonates of the alkali metals or with ammonium hydroxide or with a volatile amine, such as

fj§ morpholine, can be prepared separately, or the soap can be prepared by adding its ingredients to the polymer

tion approach can be generated in situ.

It is not yet clear why using soaps of the new heat-modified disproportionated natural resins improved conversions in the emulsion copolymerization of butadiene (1,3) with styrene or acrylonitrile be achieved. It seems that they make soap micelles with better properties, as is common consensus insists that this polymerization is initiated in such micelles. It's common knowledge that Natural resins contain substances that can act as inhibitors in the polymerization reaction. It is possible that these compounds are changed in such a way by the conditions of the heat treatment become that they no longer act as inhibitors. However, these or other theoretical ones are not decisive Possibilities, but dio improved conversions that occur when using the soaps of heat-modified disproportionated »· natural resin for the copolymerization of butadiene (1,3) with styrene or H acrylonitrile can be achieved.

It is also pointed out that the shortened polymerization time in any aqueous emulsion

ΐ; 1 merization system can be achieved in which natural resin soaps are used. So the new soaps in

ψ Butadiene-styrene-rubber and in nitrile rubber mixtures with high or low solids content in aqueous

p gen systems are used in which the monomers are usually stored at temperatures from 4 "C up to 50 to

f | 6O ⁰ C are polymerized. They can also be used together with any catalyst system that

ψ is normally used for these polymerizations.

£ i A standard recipe widely used in the manufacture of rubber is the sulfoxy

% lat recipe in which the activator is sodium formaldehyde sulfoxylate, ferrous sulfate or another chelating agent

|| Contains agent (see. Whitby, "Synthetic Rubber", 1954 edition, page 217). A typical butadiene-styrene-poly

ΐ | merization preparation used both on an industrial scale and in the laboratory is that

/ Λ »1500-type SBR recipe«. For test purposes it is used in the following form.

; r; Laboratory recipe 1500

ffi

ζί; The following ingredients are placed in a 907 cm ³ bottle and polymerized for 8 hours at 5 ° C

'^ i left.

';■;' [ Butadiene- (1,3) 107 g, freshly distilled

ΐ Styrene 46 g, stabilized with tert-butylpyrocatechol

5 x water 275 g

;;; Potassium soap from disproportionated natural resin 6.90 g on the pure solids content of this

■: "■■■ based on emulsifying agent (without water)

';.' Sodium salt of one

^: - 'Naphthalenesulfonic acid-formaldehyde condensate 0.150 g

S electrolyte (KCl) 0.610 g

; '.' EDTA (chelating agent) 0.025 g. based on 100% tetrasodium salt

: '. of ethylenediaminetetraacetic acid

tert-dodecyl mercaptan 0.310 g (100%)

p-menthane hydroperoxide 0.038 to 0.046 g (100%) o5

Sodium formaldehyde sulfoxylate of the formula

NaHSO ₂ • CH ₂ O • 2 H ₂ O 0.036 to 0.043 g

Ferrous sulfate 0.013 to 0.015 g

Oxygen is a well-known inhibitor for the polymerization of styrene-butadiene-O ^ mixtures. Because it

It is difficult to remove all traces of oxygen from an industrial polymerization system

sometimes air is voluntarily introduced into the test system in an amount of 4 ml per 100 g of monomers determine its effect on polymerization. This amount corresponds to 6.2 ml for the one given above Recipe. This addition was made in all examples unless otherwise stated.

The loading is carried out as follows:

The potassium soap of the disproportionated natural resin, the sodium salt of a naphthalenesulfonic acid formal

Dehydration condensate and KCl are dissolved in 200 g of distilled water and adjusted to a pH of 10.5 with 2N KOH set. This solution is poured into a bottle along with another 75 ml of distilled water

ίο was previously flushed with nitrogen. Then the styrene is added to the bottle except for the amount required for Dissolution of the p-menthane hydroperoxide and tert-butyl mercaptan is used. Then the tert-Dodecyl mercaptan and p-menthane hydroperoxide dissolved separately in styrene are added to the bottle. On that

a small excess of butadiene- (13) is weighed into the bottle. The excess will evaporate and the bottle is quickly closed with a metal cap and neoprene gasket. The cap has a small hole so that solutions can be added through the neoprene seal with the help of a medicine syringe and Samples can be taken.

The bottles are placed in compartments of a polymerizer kept at 5 ° C. the Bottles are rotated until the contents are completely emulsified and cooled. Then each bottle is poured given a suitable amount of the ferrous sulfate, sodium formaldehyde sulfoxylate and sodium EDTA solution, which beforehand by dissolving sodium formaldehyde sulfoxylate, sodium EDTA or ferrous sulfate under nitrogen in water, and the bottles are rotated for 8 hours, whereupon the Implementation is canceled.

After the reaction time of 8 hours, the amount of solids is determined. This vVert becomes the percentage conversion of monomers into polymer calculated.

Alkali metal soaps of the heat-modified disproportionated tall oil resins can also be used as emulsifiers used to manufacture nitrile rubber. For example, you can use them instead of the soap flakes be used in the recipe given on page 802 of the Whitby book.

The natural resin used in Examples 1 to 4 was catalytic according to US Pat. No. 2,138,183 produced disproportionated tall oil resin with the following properties:

Acid number 167

Saponification number 173

Unsaponifiables,% 7.0

Abietic acid (U.V.), o / o 0.7

Optical rotation +53

Softening point, ⁰ C 74

The invention will be further elucidated by the following examples, which illustrate preferred embodiments explained.

Example 1 and Comparative Experiment A

634 g of the disproportionated tall oil resin described above was placed in a 10OC ml three-necked flask

given, which was equipped with a gas inlet tube, a thermometer and a steam-heated reflux condenser. It was fed to heat and maintain a temperature of 260-270 ⁰ C for 18 hours without stirring, thereby obtaining introduced for the protection of the resin during the treatment about! 00 ml Siickstoffgas per minute.

The obtained heat-modified disproportionated tall oil resin was made by reacting it with potassium hydroxide transferred to his potassium soap. Made from a portion of the disproportionated resin described above that does not was modified by heating, a potassium soap was also prepared for use as a control. Both soaps were used as emulsifiers for Laboratory Recipe 1500.

Eight polymerization bottles, four for each soap, were prepared. After all components of the

Prescription was filled in two bottles containing the heat-modified resin soap, and in two Bottles containing the unmodified soap were introduced with a syringe of 6.2 ml of air. Then through 8 The polymerization was carried out by shaking at 5 ° C. for hours. Then the degree of conversion was certainly. The following results are in each case the mean values of two / one bottles.

Table I.

Example No.% Conversion, Monomers' .n Polymer

or comparative experiment no air 62 ml air

A 60.1 29.4

1 70.7 63.7

Examples 2 to 4 and Comparative Experiment B as well as
Examples 5 and 6

In the apparatus described in Example 1 further shares the same disproportionated Taiiöiharzes were charged and heated for various times while passing in about 100 ml per minute of nitrogen at 270 ⁰ C. Samples were taken after the first 3 hours, after a further 7 hours and after a further 6 hours and converted into their potassium soaps. These soaps were used as described above along with a potassium soap of unmodified disproportionated natural resin as a control for 1500-type SBR recipes. 2 bottles were filled with each sample, whereupon 6.2 ml of air were added and the polymerization was carried out at 5 ° C. for 8 hours. The following results are the mean values of two bottles in each case.

Table Il Hours at 270'C Vo conversion of
Styrene butadiene
in polymer Example no.
or comparison test 3
10
16 27.7
35.5
43.8
76.7 ß
2
3
4th

These results show that the benefits achieved by heat modification of the disproportionated tall oil resin increase with further heating, but that the greatest improvements occur in the latter half of the heating period, ie after about 8 to 18 hours of heating at 270 ° C. be achieved. Other experiments have shown that comparable results are achieved with much shorter curing times when higher temperatures of up to about 30O ⁰ C are used. For example, with the potassium soap of the same disproportionated resin, if it is heated to 300 ⁰ C in the absence of oxygen, a conversion of monomer into polymer of 50% is achieved (Example 5), while a modified one by heating at the same temperature for 4 hours Resin is obtained, the potassium soap of which gives a 60% conversion (Example 6). Both results were obtained after the test described above with the addition of 6.2 ml of air.

Examples 7 to 11 and Comparative Experiment C

The influence of different temperatures with the same heating time is also derived from the following values for the conversion to be seen with potassium soaps of an equally disproportionate Taiiöi resin a delivery other than that used in Examples 1-7 were achieved, which was only 2 hours on the specified temperatures was heated. The same recipe and were used for the experiments with these soaps the same procedure as in Examples 2-6 was used.

Table III Heat treatment % Conversion Example no. Hot temperature or comparison test "C 11th C. 200 14th 7th 225 17th 8th 250 28 9 2? 5 33 '0 300 41 11th

Examples 12 to 21 and Comparative Experiments D, E and F

Samples of an equally disproportionate Taiiöi resin from a shipment other than that in the Examples 1-7 were used in the apparatus described in Example 1 during times and on heated to the temperatures given in Table IV below. After conversion to potassium soaps They were used to make styrene-butadiene copolymers according to the SBR-1500 recipe Polymerization was carried out for 8 hours at 5 ° C. in the presence of 6.2 ml of air, after which the following Conversion of the monomers into polymers in percent was determined:

Table IV

Example No. Heat Treatment% Conversion to

or comparative test hours temperature of polymer

⁰ C

IO H

15 17

20 20

0 - 22nd 8th 250 39 12th 250 40 16 250 39 0 19th 8th 275 48 12th 275 48 16 275 57 0 17th 2 300 44 3 300 46 4th 300 46 5 300 49

Examples 22 to 35 and comparative experiments G to]

The procedure of Examples 12-21 was carried out using samples of a disproportionated tall oil resin as the starting material repeated, which was prepared according to the details of US Pat. No. 3,377,334 and the following Features:

Acid number 157

Unsaponifiable, ° / o 9

Abietic acid. % 0.02

Optical rotation 448

Softening Point, "C 65

These samples were modified by the heat treatment given in Table V below then transferred to their potassium soaps. These soaps were used as ingredients in Recipe 1500 and tested as described in Examples 12 to 21 in the presence of oxygen. There were the following Get results:

Table V

Example no. Heat treatment ° / o conversion to

or comparative test hours temperature of polymer

⁰ C

45

50

55

60 31

65 34

O - 18th 8th 250 20th 12th 250 24 16 250 26th O 23 8th 275 32 12th 275 34 16 275 41 O 34 2 290 37 3 290 38 4th 290 38 5 290 45 O 34 2 300 40 4th 300 48 (Jl 300 51 6th 300 56

Examples 36 and 37 and comparative experiments K. and L

Tree sap (from dead wood) and gum resin (from living trees) were made up to one using the palladium catalyst and the method described in US Pat. No. 2,138,183
Abietic acid content of less than 1% disproportionate. A portion of each resin was then heat-modified by treating for two hours at 300 ° C. under a protective atmosphere of nitrogen gas.

Samples of the unmodified disproportionated resins and the heat-modified disproportionated ones
Resins were then used as components of the recipe 1500 by polymerizing for 8 hours at 5 ^° C. after
Operation of the examples 12 to 21 tested with and without the addition of air. The results are in the following
Table VI given. ok

«V 45

1 55

Table VI % Conversion
without air 6.2 ml of air Example no.
or comparison test Tree sap 37
45 9
36 1 K
36 Gum resin 27
42 4th
32 L.
37 ΐ. J

Claims (1)

Claim: Process for the copolymerization of butadiene (13) with styrene or acrylonitrile in an aqueous emulsion, in known systems for the emulsion polymerization of olefins, in the presence of an inert gas atmosphere heat-modified disproportionated resin acid in the form of an alkali salt or a salt with ammonia or a water-soluble amine and in the presence of a free radical generator Catalyst, characterized in that salts of such resin acids are used which by heating disproportionated resin acids at atmospheric pressure for 1 to 18 hours a temperature of 250 to 300 ° C have been obtained.