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Oxymethylene polymers and process for the preparation thereof

A technology of oxymethylene and polymers, applied in the field of oxymethylene polymers, can solve problems such as insufficient hydrolytic stability, unstable end groups of oxymethylene polymers, and inability to separate

Inactive Publication Date: 2011-06-01
TICONA GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] However, the initiator systems (heteropolyacid and solvent) known in the prior art suffer from insufficient hydrolytic stability
In addition, the solvents required to dissolve the heteropolyacids mentioned in the prior art can cause problems in production plants
[0010] Solvents known in the prior art for dissolving heteropolyacids are not inert under the polymerization conditions of trioxane and lead to reduced molecular weight and unstable end groups of the obtained oxymethylene polymers
Additionally, the solvents disclosed in the prior art for dissolving heteropolyacids cannot be easily separated from the product stream due to the formation of an azeotrope with trioxane
In addition, the solvents disclosed in the prior art do not meet the safety and environmental requirements required

Method used

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  • Oxymethylene polymers and process for the preparation thereof
  • Oxymethylene polymers and process for the preparation thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0109] Embodiment 1 (according to the present invention)

[0110] By adding 12-tungstophosphoric acid (H 3 PW 12 o 40 )[CAS 12501-23-4] is dissolved in dimethyl adipate (DMA) to prepare a cationic polymerization initiator. The concentration of heteropolyacid in DMA is 0.2 wt%.

[0111] 30 μl heteropolyacid (H 3 PW 12 o 40 ) in dimethyl adipate was added at 70° C. to 100 g of trioxane containing 100 ppm methylal. This corresponds to an initiator level of 0.6 ppm. The initiation time is 10-20 seconds, and the polymerization is completed in about 1 minute. The crude material was removed from the beaker, crushed into pieces and weighed (crude polymer yield).

[0112] Crude polymer yield was 92% with a hydrolysis loss of 36%.

[0113] The overall yield of hydrolyzed polymer was 59% (based on trioxane).

[0114] MVR at 190°C is 4.6ml / 10min.

[0115] GPC analysis showed no clear distinct peaks for the low molecular weight fraction. figure 1 GPC traces are shown in (Mw = ...

Embodiment 2 and comparative Embodiment 1

[0117] Conduct factory trials to manufacture high-strength POM. A Honda twin screw extruder was used. Table 1 below summarizes the operating conditions for Comparative Polymer 1 (Comparative Example 1) and Inventive Example 2.

[0118] Table 1:

[0119]

Example 2

Comparative Example 1

Trioxane feed rate

20000lb / hr

20000lb / hr

Methylal concentration

550ppm

350

Dioxolane concentration

2000ppm

3.2％

Initiator

HPA 1)

BF 3

BF in trioxane 3 concentration

10-20ppm

DMA 2) Medium HPA 1) concentration

1000ppm

---

HPA in trioxane 1) concentration

2ppm

---

Reactor screw speed

30rpm

30rpm

[0120] 1) h 3 PW 12 o 40

[0121] 2) Dimethyl adipate

[0122] In table 1, under the conditions shown in embodiment 2, the polymer with acceptable low molecular weight fraction is obtained, such as figure 2 Shown in the GPC curve in (grey...

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PUM

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Abstract

The present invention relates to a process for the preparation of oxymethylene polymers as well as oxymethylene polymers obtainable therefrom. The process includes polymerization of a monomer, which forms -CH2-O- units in the presence of an acetal of formaldehyde or a polyhydric alcohol and an initiator for cationic polymerization. The initiator may be a heteropoly acid or an acid salt thereof which is dissolved in an alkyl ester of a polybasic carboxylic acid.

Description

field of invention [0001] The present invention relates to a process for the preparation of oxymethylene polymers and to oxymethylene polymers obtainable therefrom. Background technique [0002] Oxymethylene polymers are obtainable by cation-initiated or anion-initiated polymerization of formaldehyde. [0003] Stabilized oxymethylene polymers can be achieved by cationic copolymerization of formaldehyde unit-forming monomers, preferably trioxane, with small amounts of comonomers and thereby substantially random incorporation of small amounts of oxyalkylene units into the chain And made. Molecular weight regulation is achieved by transfer agents, usually dialkyl formals. Copolymerizations with stable terminal hydroxyalkyl groups (from comonomer) and terminal alkyl groups (from transfer agent) are obtained by degrading unstable ends in alkaline media up to the first oxyalkylene unit (hydrolysis) thing. Thus, for example, EP-A-504,405 discloses oxymethylene units which conta...

Claims

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Application Information

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IPC IPC(8): C08G2/06C08G2/08C08G2/10C08G2/18C08G2/22
CPCC08G2/10C08G2/06C08L59/02C08L67/025C08L2666/16
Inventor M·豪布斯M·霍夫莫克尔J·林瑙R·格罗纳L·拉森
Owner TICONA GMBH
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