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Method for preserving cyclic condensed formol

A cyclic formal and formaldehyde technology, which is used in indoor sanitary piping installations, waterway systems, drainage structures, etc.

Inactive Publication Date: 2007-07-25
MITSUBISHI GAS CHEM CO INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In addition, it is disclosed that at least one hindered phenol having a molecular weight of at least 350 is added to the group selected from 1,3-dioxolane, 1,3-dioxane, 1, the method in the cyclic formal of 4-butanediol formal, diethylene glycol formal and 1,3,5-trioxepane (trioxepane), but this method needs further improvement (referring to patent publication 4 )

Method used

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Examples

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Comparison scheme
Effect test

preparation example Construction

[0036]

[0037] The preparation method of the present invention is a method for preparing a polyoxymethylene copolymer by copolymerization of cyclic formal and trioxane, wherein, using The resulting cyclic formal.

[0038] As mentioned above, the cyclic formal in this preparation method is preferably derived from formaldehyde and an aliphatic diol containing 2 to 4 carbon atoms. Cyclic formals are exemplified as described above, with 1,3-dioxolane being particularly preferred.

[0039] Phenol is preferably added in an amount of 10-2,000 ppm, more preferably 10-1,000 ppm.

[0040]The preparation method of the present invention is characterized in that 5-10,000 ppm of phenol is added to the cyclic formal containing low peroxide content before the preservation of the cyclic formal, and the cyclic formal with suppressed generation of peroxide used as starting material. That is, the present invention uses a cyclic formal obtained by adding 5-10,000 ppm of phenol after preparat...

Embodiment 1

[0088] The cyclic formal 1,3-dioxolane (product of Tokyo Kasei kogyo Co., Ltd.) used in the preservation test was purified by distillation before use. The water and peroxide contents in the 1,3-dioxolane obtained immediately after distillation were 5 ppm and 2 ppm, respectively. 100 g of purified 1,3-dioxolane was charged into a 200 ml Erlenmeyer flask, and phenol was added in an amount of 30 ppm based on 1,3-dicyclopentyloxy. Then, the atmosphere in the system was replaced with nitrogen, and then left to stand at 60°C with the stopper sealed. The peroxide content in 1,3-dioxolane was 8 ppm after 10 days and 15 ppm in 1,3-dioxolane after 20 days.

Embodiment 2-4

[0090] Repeat the method of Example 1, but the amount of phenol added is as shown in Table 1. The results are shown in Table 1.

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Abstract

A method for preserving cyclic formal is provided, thereby preserving monomer having improved thermostability for production of polyoxymethylene copolymer without reduction of quality. The method for preserving cyclic formal comprises adding 5 to 10,000 ppm, preferably 10 to 2,000 ppm of phenol into cyclic formal, wherein the cyclic formal comprises 5 ppm or less of peroxides; the cyclic formal is derived from formaldehyde and C2-C4 aliphatic diol; the cyclic formal is 1,3-dioxolane. The method for preparing polyoxymethylene copolymer comprises copolymerization of 0.5 to 40 mol% of cyclic formal and trioxane.

Description

technical field [0001] The present invention relates to a method for preserving cyclic formals. The present invention also relates to a cyclic formal composition suitable for the preservation method. In addition, the present invention relates to a method for preparing a polyoxymethylene copolymer by using the preserved cyclic formal of the present invention. Background technique [0002] In some cases, polyoxymethylene copolymers prepared from cyclic oligomers such as trioxane or tetraoxane and long-term storage of cyclic formal may not have satisfactory thermal stability, and the cyclic formal can be used Cationic active catalysts are copolymerized with oligomers. [0003] It is well known that the reason for the decrease in thermal stability is the peroxide derivative contained in the cyclic formal. Although present in trace amounts, cyclic formal will still decompose even at room temperature, especially when it is exposed to a temperature of tens of degrees (°C) to 100...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D317/12C07D319/06C07D321/06
CPCE03C1/264E03F5/14
Inventor 须长大辅中谷大吾古川昌典中岛正之
Owner MITSUBISHI GAS CHEM CO INC
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