DE1206157B - Process for the production of internal copolymers of trioxane - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

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C08g

German class: 39 c-19

1 206 157
F40273IVd / 39c July 19, 1963 December 2, 1965

It is known that polyoxymethylenes which can be used as plastics either by anionic polymerization of formaldehyde or by cationic polymerization of trioxane, the cyclic trimer of formaldehyde to produce high molecular weight products. Homopolymeric polyoxymethylene contains unstable terminal semi-formal groups and is exposed to thermal Use up to a small percentage after the so-called zipper ίο reaction degraded with the formation of monomeric formaldehyde. This reaction arises each time a semi-formal molecule is broken down, a new unstable semi-formal end group is created on the macromolecule. '5

In order to convert polyoxymethylenes with terminal semi-formal groups into technically usable plastics, it is necessary to remove the end groups, e.g. B. by esterification to stabilize. For this purpose, the polymer z. B. dissolved in acetic anhydride at 16O ⁰ C. After the esterification, it is necessary to remove the excess acetic anhydride and the acetic acid that has formed from the polymer again by laborious cleaning operations. In addition, the polymers stabilized in this way are not resistant to alkalis because of the risk of saponification. Despite the actually quite effective stabilization of the products by esterification, there is a risk of a re-establishment of a zipper reaction if such a molecular chain stabilized by end group esterification is in the inner part of the chain, e.g. B. under the action of elevated temperatures breaks. This also applies to products whose end groups have been etherified. In addition, in the case of end group etherification, it is difficult to adjust the molecular weight.

Favorable results of the stabilization of polyoxymethylenes is obtained by trioxane with saturated cyclic ethers or cyclic ethers Formal forms such as B. ethylene oxide or diethylene glycol formally copolymerized. For the purpose of The unstable end groups of the copolymers are stabilized after the polymerization Hydrolysis degraded, the zipper reaction only going as far as the comonomer molecules. If the molecular chain is thermally split during processing of the polymer, then the chain in question can only be broken down as far as the next comonomer molecules, as a result of which a better thermal stability is achieved. Mixed polyacetals, especially copolymers with high content of polyoxymethylene units, of processes for the production of ternary copolymers of trioxane

Applicant:

Farbwerke Hoechst Aktiengesellschaft formerly Master Lucius & Brüning, Frankfurt / M.

Named as inventor:

Dipl.-Chem. Dr. Klaus Weissermel, Frankfurt / M.-Höchst;

Dipl.-Chem. Dr. Edgar Fischer, Frankfurt / M.-Schwanheim;

Dipl.-Chem. Dr. Claus Schott, Hofheim (Taunus)

high molecular weight and sufficient stability are already used in various areas, among other things for the production of injection-molded and extruded plastic objects, which are also used in elevated temperatures can be used with success.

It is also known ternary copolymers of trioxane, cyclic ethers or formals and bifunctional Establish compounds that crosslink during polymerization.

It has now been found that crosslinkable ternary copolymers of trioxane by polymerizing 80 to 98.99 percent by weight of trioxane with 1 to 10 percent by weight of a cyclic ether or a cyclic formal and 0.01 to 10 percent by weight of a bifunctional compound in the presence of cationically active catalysts temperatures may advantageously be prepared from -50 to +100 ⁰ C, when using the prepolymers as bifunctional compounds comonomers which contain second, first, a cyclic ether or cyclic acetal, and a cyclic carbonate group, or the like.

In the terpolymerization of trioxane at temperatures between -50 and +100 ⁰ C initially participates only the cyclic ether or acetal in the reaction, while the carbonate group remains intact.

The copolymers prepared according to the invention can be used for the production of foams

509 740/436

be turned. In this case, it proves to be expedient to bring the product obtained by terpolymerization in the molten state into the intended shape and then to foam it. It is also possible to use the CO2 z. Withdrawing, in a suitable device provided with a vacuum extruder and ran down the degassed product by about ¹ Iz to 1 hour annealing at 180 to 220 ⁰ C in a refractory hardened substance.

For the process according to the invention come as bifunctional compounds comonomers, each a cyclic ether group, preferably an epoxy group or cyclic acetal group, and a cyclic one Contain carbonate group, as well as prepolymers of these compounds. There are those Aliphatic and cycloaliphatic bifunctional compounds are superior to aromatic compounds, since the aromatic nucleus lead to low molecular weights as a result of a chain transfer reaction can, which is undesirable for some purposes.

Because of their good reactivity and easy accessibility, β, γ - epoxypropoxy- β'-γ'- carbonate - propoxyalkanes of the general formula are of particular interest

CH ₂ - CH - CH ₂ - O - (CHg) _n - O - CH ₂ - CH CH ₂

O O -CO-O

in particular those, optionally branched, compounds with η = 1 to 8 are suitable. There are also glycerol-1-glycidyl ether carbonate, 2,4,6-trioxa-3-oxobicyclo [3,1,0] hexane and 3,5,8-trioxa-4-oxobicyclo [5, 1,0] octane or prepolymers of these 'compounds are extremely effective.

Ethylene oxide, dioxolane or diethylene glycol formal are suitable as cyclic ethers or formals.

The cationic polymerization can be carried out by methods known per se, in bulk, in Solution or in suspension. Aliphatic hydrocarbons, in particular those with 6 to 18 carbon atoms and aliphatic, preferably chlorine or fluorine-containing halogenated hydrocarbons, in particular those with 1 to 4 carbon atoms or aliphatic ethers with 2 to 4 carbon atoms can be used. Particularly smooth the polymerization proceeds in bulk.

The reaction is carried out at temperatures, · in which the trioxane does not crystallize out, that is depending on the used solvent at -50 to + 10O ⁰ C, in the absence of solvents at from +20 to + 100 ⁰ C, but preferably at +60 to + 8O ⁰ C.

All substances that allow cationic polymerization can be used as catalysts able to trigger such. B. inorganic and organic acids, acid halides and in particular Lewis acids (definition of Lewis acids, see K ο r tü m, Textbook of Electrochemistry, Wiesbaden 1948, pp. 300 and 301). Of the latter, are boron trifluoride etherates good usable. Diazonium fluoroborates are also very suitable. Basically you can but all known, e.g. B. those described in Belgian patent 585 980 cationic Catalysts are used.

The concentration of the catalysts can vary within wide limits. It depends on the Type of catalyst and whether high or low molecular weight copolymers are produced should be. It can be between 0.0001 and 1 percent by weight, based on the total monomer mixture, lie. Generally from 0.001 to 0.1 weight percent catalyst is used.

Since the catalyst tends to degrade the polymer, especially in the presence of moisture, it is advisable to neutralize it immediately after the end of the polymerization, e.g. B. with ammonia or with methanolic or acetone solutions of primary, secondary or tertiary amines, preferably those of aliphatic hydrocarbons with 1 to 4 carbon atoms, as well as mono-, Diethanolamine or triethanolamine.

The removal of unstable hemiacetal end groups can be carried out in a known manner, as in the case of other mixed polyacetals. It is expedient to suspend the polymer in aqueous ammonia at temperatures of 100 to 200 ^° C., with a swelling agent such as methanol or n-propanol also being present, or to dissolve the polymer in an alkaline medium at temperatures above 100 ^° C. with subsequent reprecipitation . As solvents are, for. B. benzyl alcohol, ethylene glycol monoethyl ether or a mixture of 60% methanol and 40% water and suitable as alkalis ammonia and aliphatic amines.

However, the end group can also in a known manner in the absence of solvents in the melt in the presence of stabilizers, expediently carried out at temperatures between 160 and 200 ⁰ C.

The stabilization of the polymer against the influence of heat, light and oxygen can be carried out as in the known trioxane copolymers take place. As heat stabilizers, for. B. polyamides, amides Polybasic carboxylic acids, amidines and urea compounds suitable as oxidation stabilizers Phenols, especially bisphenols and aromatic amines. α-Oxybenzophenone derivatives are suitable for light stabilization.

The technical advance of the process of the invention over the process disclosed in French Patent 1,221,148 method is that the copolymers according to the invention by heating to 180 to 22O ⁰ C due to reaction of the second functional group of the bifunctional compound, with elimination of CO _2, optionally with Addition of ammonia or hydroxyl compounds or by tempering, branched or crosslinked and thus converted into poorly to infusible plastic objects and poorly meltable foam bodies, whereas in the known process crosslinking occurs already during the polymerization.

example 1

100 g of freshly distilled liquid trioxane, 2 g of ethylene oxide, 0.1 g of monocarbonate of 1,3-butanediol ^{diglycidyl ether are poured into a 200 cm 3} screw glass and filled with 15 mg of p-nitrophenyl diazonium

fluoroborate added. The screw-top jar is sealed and placed in a water bath at 70 ⁰ C. The beginning of the polymerization is indicated by cloudiness after a few minutes. After the reaction has ended, the block is ground and boiled with methanol, which contains 1% triethanolamine. After the homogeneous hydrolysis of the product in the presence of diethylene glycol monoethyl ether in the presence of 1% amine, 1 hour at 150 ⁰ C and then boiling the Diäthylenglykolmonoäthyläthers with methanol one obtains a white powder. The yield is 78%, the melt index 7.8 (ASTM D 1238-52 T), rireä the reduced viscosity, 0.68 (determined on a 0.5% solution of the polymer in butyrolactone containing 2% diphenylamine as stabilizer contains at 14O ⁰ C).

Example 2

1000 cm ^{3 of} freshly distilled liquid trioxane are ^{mixed with 20 cm 3 of} ethylene oxide and 1 cm ^{3 of} glycidyl ether 2,3-carbonate in a flask together with 160 mg of p-nitrophenyldiazonium fluoroborate as a catalyst and the whole is placed in a stainless steel mold flushed with nitrogen, which is in a water bath of 7O ⁰ C is located. The course of the reaction is measured with a thermocouple. The temperature in the block rises to about 88 ^° C. and then falls again. After an hour, the mold is quenched in cold water and the block removed and ground. The polymer is boiled with methanol containing 1% triethanolamine, then washed with methanol and then dried. Finally, it is subjected to heterogeneous hydrolysis in 1% ammonia solution in a ratio of 1: 4. The hydrolysis temperature is 144 ° C, the pressure 3.6 atü. Finally the product is washed and dried again. The yield is 72%, the melt index 8.5.

Example 3

100 g of freshly distilled trioxane, 2 g of ethylene oxide and 2 g of prepolymer 3,5,8-trioxa-4-oxobicyclo [5, l, 0] octane with a molecular weight of 1100 are mixed and placed in a 200 cm ³ screw-top jar in the presence of 30 mg of p-nitrophenyldiazonium fluoroborate ^{polymerized at 70 °} C. and worked up as in Example 1. Unlike the experiment in Example 1 the polymer at 150 ⁰ C in Äthyldiglykol is swelled, but not dissolved, so that this is merely a heterogeneous end group stabilization takes place. The polymer yield is 68%. When the polymer is thermally treated, a foam body with a volume weight of 0.4 g / cm ³ is formed with elimination of CO2.

Claims (1)

Claim: Process for the preparation of ternary copolymers of trioxane by polymerizing 80 to 98.99 percent by weight of trioxane with 1 to 10 percent by weight of a cyclic ether or a cyclic formal and 0.01 to 10 percent by weight of a bifunctional compound in the presence of cationically active catalysts at temperatures of - 50 to + 10O ⁰ C, characterized in that the bifunctional compounds used are comonomers which firstly contain a cyclic ether or cyclic acetal group and secondly a cyclic carbonate group, or prepolymers thereof. Considered publications:
French patent specification no. 1 221 148,
271 297.