DE1251024B - Process for the production of copolymers of tnoxane - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C08g

COÖo

German class: 39 c -19

Number: 1 251 024

File number: D 46564IV d / 39 c

Filing date: February 19, 1965

Opening day: September 28, 1967

From French patent 1,322,375 it is known from formaldehyde or its low Oligomers - including trioxane - and a mono- or poly-ethylenically unsaturated one Compound under the influence of a catalyst to produce copolymers, which are through a the corresponding homopolymers are characterized by superior thermal stability. The obtainable according to the invention As will be shown, products are these known copolymers with respect to Much superior to thermal stability.

The invention relates to a process for the preparation of copolymers of trioxane by polymerizing 90 to 99.9 mol percent trioxane with 0.10 to 10 mol percent of an unsaturated hydrocarbon under essentially anhydrous conditions in the presence of polymerization catalysts at temperatures from 30 to 100 ^° C. which is characterized in that the unsaturated hydrocarbons used are compounds of the formula Process for the preparation of copolymers
of trioxane

Applicant:

Diamond Alkali Company,

Cleveland, Ohio (V. St. A.)

Representative:

Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse
and Dr. E. v. Pechmann, patent attorneys,
Munich 90, Schweigerstr. 2

Named as inventor:

Irving Rosen, Painesville, Ohio (V. St. A.)

Claimed priority:

V. St. v. America February 20, 1964 (346 099)

CHR ₇

used in which R ₁ to R _{7 are} hydrogen atoms or not more than one R is an alkyl radical having 1 to 4 carbon atoms.

Among the substituted norbornadiene derivatives used according to the invention, preference is given to those d> e in the 2- or 4-position of the norbornadiene ring carry an alkyl radical having 1 to 4 carbon atoms, e.g. B. 2-methylnorbomadiene or 4-methylnorbomadiene. However, preference is given to using the unsubstituted in the process according to the invention Norbornadiene, which is readily available.

The copolymers obtainable according to the invention are solid substances of medium to high molecular weight which inherently have a high degree of thermal stability and ^{do not suffer any significant weight loss due to decomposition at temperatures of 200 °} C. and above, in contrast to the polyoxy prepared and stabilized in a similar manner methylenes, which, when heated, soon undergo significant or even complete decomposition, which severely limits their use.

"Heat stability" or "thermal stability" of the copolymers prepared according to the invention is to be understood as the value which indicates the constant rate at which these copolymers are decomposed at a higher temperature; a temperature is chosen at which the decomposition can be measured easily and precisely. This value, ie the reaction rate constant in the case of thermal decomposition, is measured according to known methods for thermogravimetric analysis. When the experiment is carried out, the copolymer is kept at 240 ^° C. and the degree of decomposition, measured as weight loss, and the experiment time in minutes are recorded automatically. The rate of decomposition of the copolymer is then obtained by plotting the logarithm of the number of percent by weight of the remaining undecomposed copolymer as the ordinate against the time in the oven. The curve obtained in this way shows that the copolymer, after initially decomposing very rapidly, decomposes much more slowly and at a constant rate during the main period of the experiment, which is characteristic of the stable nature of the copolymer. The reaction rate constant for the thermal decomposition of the copolymer prepared according to the invention is determined on the basis of the last-mentioned part of the decomposition curve and expressed in percent by weight per minute. The copolymers prepared according to the invention generally show, on thermal decomposition at 240 ° C., a reaction rate constant of at most 0.6 percent by weight each

709 649/437

Minute, preferably 0.4 percent by weight per minute or less.

If the copolymerization process is considered purely theoretically, it appears that the norbornadiene comonomer in the growing chain primarily via the carbon atoms in the 3- and 5-positions on the Norbornadiene monomer molecule occurs (see formula 1 above). Simultaneously with this addition reaction is due to a newly formed bond between the ring carbon atoms 2 and 6 the Ring structure rearranged to the Nortricyclenkonfiguration. The resulting copolymer chain can thus each recurring nortricycle units between the individual oxymethylene groups of the following structure:

R ⁴

CHR '

R ⁶

R ³ -

J _R 2

R ¹

wherein R ¹ to R ^{7 are} hydrogen atoms or not more than one R is an alkyl radical having 1 to 4 carbon atoms. Since the characteristic infrared absorption bands for nortricyclene and cyclopropane can be observed in the copolymers obtained, it is probable that the copolymerization proceeds primarily in the above sense.

However, the copolymerization can also start at other carbon atoms in the norbornadiene ring, for example on the ring carbon atoms 2 and 3, so that the resulting copolymer chain is recurring Has norbornene groups or units represented by the following formula:

R ³

R ²

R ⁴ C CHR ⁷

R ⁶

wherein R ¹ to R ^{7 have} the above meaning.

It is also possible that the norbornadiene comonomer both in the form of Nortricyclen- as is also built into the polymer chain by norbornene units.

The Nortricyclen and / or norbornene units can, however, also as chain sections in which more than one of these units are directly linked to one another.

Finally, there is the possibility that, for example, an addition on both double bonds of the Norbornadiene molecule takes place.

The copolymers produced according to the invention are composed of about 90 to 99.9 mol percent oxymethylene units and about 0.10 to 10 mole percent of regular repeating units together, the are derived from the norbornadiene comonomer. Preferably about 0.3 to 5 mole percent are norbornadiene units and 95 to 99.7 mole percent oxymethylene repeating units are present.

The composition of the copolymers was determined by carbon and hydrogen elemental analysis.

Infrared analysis can also be used to determine the chemical structure of the copolymers produced according to the invention, in particular with regard to the presence of nortricyclene units in the chain clear up.

The copolymers produced according to the invention have melting points within the range from 150 to 180 ^° C. or higher. The copolymers resemble polyoxymethylene in appearance, and those with similar melting points also have similar properties. The mean molecular weights of the

ίο copolymers are 6000-90 000. For the production of plastic articles used to polymers which usually have a relative viscosity of at least 0.7, measured in a 0.5 ° / ₀ solution of the copolymer in p-chlorophenol with 2 weight percent of a pinene at 6O ⁰ C. a relative viscosity in the above solution of 0.7 (6O ⁰ C) corresponds to an average molecular weight of about 10000. a particularly well workable and therefore preferred copolymers have a relative viscosity of at least 1.0, an average Molecular weight of about 17,000.

The process according to the invention is carried out in the presence of an ionic polymerization catalyst. Suitable compounds of this type are Lewis acids, e.g. B. metal halides such as the halides of aluminum, boron, tin, titanium, zirconium, strontium or niobium, and coordinate complexes of such metal halides with organic compounds in which oxygen, nitrogen or sulfur represent the donor atom. The coordinate complexes of boron trifluoride are particularly preferred. Suitable boron trifluoride complexes are, for example, complexes of boron trifluoride with an alcohol, a phenol, an acid, an ether, an acid anhydride, an ester, a ketone, an aldehyde, a dialkyl sulfide or a mercaptan. In particular, the boron trifluoride complexes with ethers, such as diethyl ether or dibutyl ether, are preferred. Fluoroborate aryl diazonium salts, such as phenyl diazonium fluoroborate, have also proven to be very effective. The amount of the catalyst used according to the invention is between about 5 x 10 ~ ^e and ~ 5 × 10 ⁴ moles (ie, between about 0.005 and about 0.5 mmol) per mole of trioxane. An amount of catalyst of about 0.01 to 0.1 mmol per mole of trioxane is preferred.

By reacting the starting monomer used according to the invention in the liquid state in the presence a catalyst and in the absence of a solvent or other liquid reaction medium copolymers are generally obtained in good yield (60 to 90% conversion). However, the polymerization can also be carried out in an anhydrous organic liquid, which is a solvent for trioxane and norbornadiene. The solvent used is preferably aliphatic hydrocarbons such as hexane, cyclohexane or heptane. In most cases it is the polymer formed is essentially insoluble in the solvent and can easily be filtered off.

The solvent is generally used in one concentration from 0.1 to 5 moles, preferably from 1 to 2 moles, per mole of monomer are used.

As already noted, the reaction, which proceeds either in bulk or in a solvent, is ^{carried out at temperatures between 30 and 100 °} C. and lasts for ¹ _1/2 to 20 hours. Reaction temperatures from 30 to 70 ^° C. and reaction times from 1 to 5 hours are preferred.

It was found that trace impurities, especially water, in the reaction mixture, the reaction of the monomer is very disturbing and the yield is greatly reduced. It is therefore essential that the copolymerization is carried out under anhydrous or at least as good as anhydrous conditions. Do you want get really good copolymers, the monomers (or the mixture of monomers and Solvent) of water do not contain more than 100, preferably at most 50 parts per million. Also the other impurities in the monomers should be removed as completely as possible before polymerizing will. In practice, the catalyst to be used is maintained immediately after its preparation Nitrogen. The monomeric starting materials are expediently through before the copolymerization careful distillation over a dehydrating agent such as sodium or phosphorus pentoxide, dried, whereby the monomer vapors formed are passed through or via an absorbent, ζ. B. a molecular sieve or Silica gel, directs. If a liquid reaction medium is used, it must be prepared with the help of the usual distillation and drying methods are completely dehydrated.

After the reaction has ended, the polymerization mixture is filtered in order to recover the precipitated product. Before drying, the product is usually cleaned by leaching it thoroughly with acetone, with hot water and again with acetone in order to remove the monomer residues and the lighter homopolymers. In addition, the copolymer is briefly ^{heated to 100 to 160 °} C. in a known manner in order to split off any loose chain ends that may be present.

As can be seen in more detail from the examples, the copolymers prepared according to the invention have inherently high level of heat resistance, which is reflected in their insignificant weight loss, d. H. by the slight decomposition in the warmth. With their excellent heat resistance these products stand in marked contrast to the unstabilized, by similar ones Process produced polyoxymethylenes, which change very quickly under the same temperature stress decompose. The copolymers prepared according to the invention, on the other hand, can be processed without you beforehand, for example by closing the terminal chain groups or by incorporating them of stabilizing additives, must further stabilize.

ίο Of course, however, such an additional one Stabilization treatment is easily possible.

The copolymers obtained according to the invention can with the help of the usual deformation or Extrusion process on all kinds of objects such as moldings, films, plates, rods, tubes, Fibers or threads are processed. The objects made from it have the excellent ones physical and chemical properties required for those made from oxymethylene homopolymers Articles are characteristic, however, are more resistant to heat than these. During processing, the Copolymers, optionally in a known manner, additives such as antioxidants, fillers, pigments, Stabilizers or processing aids, are added, as they are in the further processing of such Thermoplastics are often applied.

To demonstrate the superiority of the copolymers prepared according to the invention over the products mentioned at the outset by the process described in French Patent 1,322,375, comparative tests were carried out using 1,3- and!, S-cyclooctadiene (two compounds that are well comparable to norbornadiene) as comonomers Trioxane carried out. As a reaction medium in all cases cyclohexane was used (ratio of cyclohexane to give trioxane = 1: 1), the reaction temperature was about 68 ⁰ C and the reaction time 6 to 6 ¹ Z ₂ hours. The catalyst was boron trifluoride dibutyl etherate. The results are shown in the following overview:

Monomer

Mole percent monomer

(a) Amount of catalyst
(Mol ■ ΙΟ- ⁴ )

(b)

sales

in ⁰ / »

% stable

after 1 hour

at 220 ^° C

Relative

Viscosity in

solution

ljS-cyclooctadiene

1,5-cyclooctadiene

Norbornadiene (Example 1 of the invention)

2 1 1 0.9

1.8
0.5

9.0
33.0
80.0

(a) Based on formaldehyde, (b) Based on formaldehyde, (c) After 1 hour at 240 ^° C.

11
34
89 (c)

0.48
1.84

(The measurement of relative viscosity was conducted at 6O ⁰ C using a 0.5 ° / ₀ solution of the copolymer in p-chlorophenol with 2 weight percent of oc-pinene.)

The experiments show that the degree of conversion is higher in the process according to the invention and that, above all, the products have a disproportionately higher thermal stability (with a higher relative viscosity in Solution) than the known copolymers.

The examples serve to explain the process according to the invention in more detail:

example 1

A 100 cm ² round flask with stirrer, thermometer and inlet and outlet for nitrogen was heated to 58 ° C in an oil bath, flushed with nitrogen and treated with 35.2 g (0.391 mol) of trioxane, 1.07 g (0.023 mol) Norbornadiene and 0.01 g (0.05 mmol) boron trifluoride dibutyl etherate charged. The reaction was carried out at 100 to 103 ^{° C. in 1 hour.}

Yield: 74.9 ° / _0th The copolymer contained 0.5 mol percent norbornadiene, melting point 170 ^° C., decomposition constant at 240 ^° C. 0.56 percent by weight per minute, average molecular weight approximately 10,000.

Example 2

From 35.2 g (0.391 mol) of trioxane, 24.8 g (0.282 mol) of cyclohexane, 0.27 g (0.003 mol) of norbornadiene and A copolymer according to Example 1 was prepared with 0.01 g (0.05 mmol) of boron trifluoride dibutyl etherate. Man held the reaction mixture at 70 to 74 ° C. for 21 hours and isolate the product as described above. Yield: 80.3% with 0.25 mole percent norbornadiene, Intrinsic viscosity of 1.26, m.p. about 175 ° C. Decomposition

constant at 240 ° C 0.32 percent by weight per minute. The moldings produced therefrom show a high Heat resistance.

Comparative experiment

As a modification of Example 1, an oxymethylene homopolymer should be used from 35.2 g (0.391 mol) trioxane, 24.8 g (0.282 mol) cyclohexane and 0.092 g (0.46 mmol) of boron trifluoride dibutyl etherate. The polymer obtained has an inherent viscosity of 1.1, m.p. 177 ° C.

When testing for thermal stability by thermogravimetric analysis, the product shows a decomposition constant at 220 ^° C. of 4.83 percent by weight per minute during the first 30 minutes and later 1.5 percent by weight per minute. The polymer decomposes completely and is destroyed 60 minutes after the start of the experiment. Compared to the copolymers according to the invention, the homo polymer accordingly shows an extremely poor thermal stability.

If the homopolymer is deformed under the conditions described in the previous examples, so very poor pieces of opaque material are obtained. They are brittle and seem a bit porous too be as if they were partially developed by the decomposition of the polymer during heating Formaldehyde would be foamed.

Claims (1)

Claim: Process for the preparation of copolymers of trioxane by polymerizing 90 to 99.9 mole percent trioxane with 0.10 to 10 mole percent of an unsaturated hydrocarbon under essentially anhydrous conditions in the presence of polymerization catalysts Temperatures from 30 to 100 ° C, characterized in that the unsaturated Hydrocarbons compounds of the formula R ⁶ R ⁶ CHR ₇ R ¹ R ³ R ² used, in which R ₁ to R, hydrogen atoms or not more than one R is an alkyl radical having 1 to 4 carbon atoms. Considered publications:
French Patent No. 1,322,375.