DE1248296B - Stabilization of homo- and copolymers of formaldehyde - Google Patents

Description

GERMAN

PATENT OFFICE

EDITORIAL

German class: 39 b -22/10

Number:
File number:
Registration date:
Display day:

\ 248 296
P 36437IV c / 39 b
April 1, 1965
August 24, 1967

It is already known to use high molecular weight polymers or copolymers of formaldehyde Esterification, in particular by acetylation or by etherification of the end groups, thermally stabilize.

The copolymers produced from formaldehyde and another comonomer are also known to stabilize through a gentle heat treatment.

However, the stability of the polymer is not yet sufficient for technical purposes, and therefore one has agents stabilizing the polymers, in particular amines, hydrazines, urea derivatives and polyamides, added.

Because the homopolymers and copolymers based on formaldehyde are particularly sensitive against the combined action of an oxidizing medium and heat, one has also oxidation-retarding stabilizers, such as phenols or organic compounds, which in contain sulfur or nitrogen atoms in their molecule.

The subject of the invention is the use of 0.01 to 10 percent by weight, based on the polymer, Isatoic anhydride and / or their derivatives of the formula

CO

for stabilizing homo- and copolymers of formaldehyde, where R = hydrogen atom, alkyl, cycloalkyl, aryl, aralkyl or heterocyclic group; X and / or Y = hydrogen or halogen atom, NO ₂ , OH, OCH ₃ group and = R signify.

The amount of stabilizing agent according to the invention to be used is between 0.01 and 10 percent by weight, based on the polymer or copolymer to be stabilized, and is preferably between 0.1 and 2 percent by weight, based on the polymer or copolymer to be treated.

Examples of the stabilizing compounds which are particularly suitable for the process according to the invention are isatic acid anhydride and its derivatives, such as in particular 5-nitro-isatic acid anhydride, 5-nitro-N-methyl stabilization of homo- and copolymers of
Formaldehyde

Applicant:

Produits Chimiques Pechiney-Saint-Gobain, Paris

Representative:

Dipl.-Ing. RH Bahr and Dipl.-Phys. E. Betzier,
Patent attorneys, Herne, Freiligrathstr. 19th

Named as inventor:

Ference Szilagyi, La Fontaine (France)

Claimed priority:

France of April 3, 1964 (969 673)

isatic anhydride, the 5-chloro- or 5-chromisatic anhydrides, to mention the 3,5-dichloro-isatic anhydride and the 5-methyl-isatic anhydride.

The isatic anhydride and its derivatives can be used in the context of the invention both for themselves and in any appropriate combinations with each other, also in combination with others conventional stabilizing agents and / or antioxidants can be used.

The incorporation of the stabilizing agents according to the invention in the homopolymers to be stabilized and copolymers can be made in any conventional manner. However, it will be useful for this purpose, methods are used that allow the stabilizing agent to be fine and homogeneous in the polymeric composition to disperse.

Thus, according to a preferred embodiment, the finely ground stabilizing agent can be introduced into the polymers and copolymers of formaldehyde by mixing in a dry mixer take place.

According to another embodiment, it is particularly advantageous in certain cases to use the stabilizing agent to be introduced directly into the molten polymer. This is best done with the Temperatures at which the polymers melt, but without thermal degradation entry.

The stabilizers to be used according to the invention are particularly suitable for etherified or esterified ones high molecular weight polymers of formaldehyde.

709 638/598

They are also responsible for the stabilization of the copolymers of formaldehyde created by a previous Heat treatment have been stabilized, suitable.

Proof of technical progress

The German Auslegeschrift 1 165 263 describes the thermal stabilization of polyoxymethylenes described by adding elemental sulfur. However, as tests have shown, the inventive Addition of isatoic anhydride and / or certain derivatives of this compound is essential better stabilization of formaldehyde homopolymers or copolymers than with Use of elemental sulfur as a stabilizing agent is the case. They also change color the polymers stabilized according to the invention far after prolonged heating to elevated temperatures less than polymers that have been stabilized using elemental sulfur.

20 Example 1

In 10 g of a high polymer of acetylated formaldehyde in powder form with a particle size distribution of between 50 and 500 μ are 100 mg of powdered isatic anhydride in a circulating Mixer mixed in.

The mixture obtained loses 32.2% of its weight after heating in air at a temperature of 222 ^{° C. for 90 minutes.} On the other hand, the same acetylated high polymer, to which no stabilizing agent according to the invention has been added, loses 40% of its weight when treated under the same conditions.

Example2

To 10 g of acetylated polyformaldehyde in powder form of the same particle size distribution as according to Example 1 is 100 mg of isatic anhydride as a heat stabilizing agent and 20 mg 4,4 - butylidene - bis - (3 - methyl - 6 - tertio - butylphenol) added as an antioxidant. the Mixing takes place in a rotating mixer.

The mixture produced in this way loses itself after 90 minutes of heating in air 222 ° C 23 7o of their weight.

A powdery acetylated polyformol, which is neither a heat stabilizer nor a die Contains oxidation retarding additive, loses 40% of its weight under the same conditions. A mixture of 10 g of the same acetylated polyformaldehyde that is not thermally stabilized which, however, contained 20 mg of an antioxidant, lost 32% of its weight under the same test conditions.

Example 3

50 mg of 5-nitro-isatinic anhydride and 20 mg of 4,4'-butylidene-bis (3-methyl 6-tertio-butylphenol) are dissolved in 50 cm ^{3 of} pure anhydrous methanol. The obtained solution will be under. Stirring, with a total duration of the stirring process of 2 hours, 10 g of powdered acetylated formaldehyde were added. The methanol is then evaporated off in vacuo with further stirring of the mixture. The dried product loses 90 minutes long heating in air at a temperature of 222 ° C 28 ° / ₀ of its weight.

Under the same experimental conditions, unstabilized acetylated polyformol loses 40% of its Weight.

Claims (1)

Claim: Use of 0.01 and 10 percent by weight, based on the polymer, of isatoic anhydride and / or their derivatives of the formula Y-X- O CO CO for stabilizing homo- and copolymers of formaldehyde, where R = hydrogen atom, alkyl, cycloalkyl, aryl, aralkyl or heterocyclic group; X and / or Y = hydrogen or halogen atom, NO ₂ , OH, OCH ₃ group and = R. Considered publications:
German interpretative document No. 1165 263. When the registration was announced, a test report and a priority document were displayed. 709 638/598 8.67 © Bundesdruckerei Berlin