Trioxane composition and method for storing same

Abstract

The present invention provides a trioxane composition which comprises trioxane as a main component, an antioxidant, and at least one alkaline organic compound selected from the group consisting of an amine compound having an alcoholic hydroxy group in the molecule thereof, a thiocarbamate compound, and an organophosphorus compound, wherein the amount of the alkaline organic compound contained is 0.01 to 10 ppm, based on the trioxane, and wherein the trioxane composition is a liquid.

Claims

1. A method for storing a polymerizable trioxane composition, the method comprising: providing a polymerizable trioxane composition comprising trioxane as a main component, an antioxidant, and an amine compound having an alcoholic hydroxy group in the molecule thereof, wherein the amount of the amine compound contained is 0.01 to 10 ppm, based on the trioxane; maintaining the polymerizable trioxane composition in a molten state for a period of time between 0.1 hour and 30 days; and, at the expiration of the period of time, subjecting the polymerizable trioxane composition to purification treatment for removing impurities.

2. The method according to claim 1, wherein the amine compound is a tertiary amine compound having an alcoholic hydroxy group in the molecule thereof.

3. The method according to claim 1, wherein the amine compound is triethanolamine.

4. The method according to claim 1, wherein the antioxidant is at least one compound selected from the group consisting of a phenolic compound and a hindered phenol compound; and wherein the amount of the antioxidant contained is 10 to 500 ppm, based on the trioxane.

5. The method according to claim 1, wherein the content of the trioxane in the trioxane composition is 95% or more.

Description

EXAMPLES

(1) Hereinbelow, the present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention.

(2) <Analytical Method for a Formaldehyde Content>

(3) A formaldehyde content was measured by an acetylacetone colorimetry method. Ultrapure water was added to 1 g of trioxane in a molten state or an extraction water so that the resultant solution had a volume of 100 ml using a 100-ml measuring flask to form a sample solution. 10 ml of the formed sample solution, and 10 ml of a solution for colorimetry, which had been prepared by dissolving 4 ml of acetylacetone and 200 g of ammonium acetate in pure water and adding pure water thereto so that the resultant solution had a volume of 1 L, were mixed together and reacted with each other in a water bath at 60 C. for 10 minutes. After air-cooling in a dark room for one hour, an absorbance at 412 nm of the resultant sample was measured using UV-1800, manufactured by Shimadzu Corporation. Using an aqueous solution having a known formaldehyde concentration, a calibration curve was prepared in advance, and a formaldehyde concentration of the trioxane was calculated from the calibration curve.

(4) With respect to only the trioxane composition in a solution state containing a solvent, an extraction water was prepared by a separation treatment in a separatory funnel using ultrapure water having the same mass as that of the trioxane composition.

(5) <Analytical Method for a Formic Acid Content>

(6) A formic acid content was measured by titration. 1 g of trioxane in a molten state or an extraction water was added to 100 ml of a solution obtained by adding 2 ml of 1/100 mol/L hydrochloric acid to 1 L of pure water. While stirring, the resultant mixture was subjected to titration with 1/100 mol/L NaOH using an automatic potentiometric titration apparatus, manufactured by Metrohm Japan Ltd. (716 DMS titrino), and a formic acid concentration of the trioxane was calculated from the resultant titration curve.

(7) <Amount of the Paraformaldehyde Formed>

(8) A glass filter was subjected to vacuum drying at 60 C. for one hour and then accurately weighed with the minimum scale of 0.001 g. The resultant glass filter was heated in a hot-air dryer to 80 C. at which the trioxane composition was not solidified, and the trioxane composition was subjected to filtration by means of suction using the glass filter before being cooled. Then, the trioxane composition deposited on the glass filter was quickly washed with acetone, and then the glass filter was subjected to vacuum drying at 60 C. for one hour and accurately weighed with the minimum scale of 0.001 g. A value obtained by dividing the increase of the mass of the glass filter by the mass of the trioxane composition subjected to filtration was determined as an amount of the paraformaldehyde formed.

(9) <Polymerization Test>

(10) Using, as a polymerization apparatus, a bench twin-shaft kneader having an inner capacity of 1 L and having a jacket and two Z-type blades, the trioxane composition was tested with respect to the polymerization reactivity by polymerization in a batch-wise manner. Hot water at 85 C. was circulated through the jacket, and further the inside of the apparatus was heated and dried using high-temperature air, and then a cover was attached to the apparatus and the system was purged with nitrogen. 320 g of the trioxane composition after being stored and 13 g of 1,3-dioxolane as a comonomer were charged through a raw material inlet, and, while stirring the resultant mixture by Z-type blades, 0.05 mmol of boron trifluoride diethyl etherate, relative to 1 mol of the trioxane, in the form of a benzene solution (solution concentration: 0.6 mmol/g) was added as a catalyst to the mixture to initiate a polymerization. After the polymerization was conducted for 900 seconds, a benzene solution (solution concentration: 5 mmol/ml) of triphenylphosphine in a molar amount corresponding to 10 times the molar amount of the catalyst used was added to the polymerization apparatus using a syringe, and mixed for 15 minutes to terminate the polymerization, obtaining a polyacetal resin. In this instance, when the polymerization yield shown below was 80% or more, a rating A was given, and, when the polymerization yield was less than 80%, a rating B was given.

(11) In Examples 1 to 3, the trioxane composition after being stored was subjected to distillation, and then the above-mentioned polymerization test was conducted with respect to the resultant composition.

(12) <Polymerization Yield>

(13) 20 Grams of the polyacetal resin, which had been subjected to termination treatment, was immersed in 20 ml of acetone, and then subjected to filtration, and the collected resin was washed with acetone three times and then, subjected to vacuum drying at 60 C. until the weight of the dried resin became constant. Subsequently, the resultant resin was accurately weighed, and a polymerization yield was determined from the following formula.

(14) Polymerization yield (%)=M1/M0100 M0: Weight before washing with acetone M1: Weight after washing with acetone and drying

Examples 1 to 3 and Comparative Example 1

(15) To a uniform solution, which had been prepared from trioxane having a purity of 99.4% and containing water in an amount of 3,000 ppm, formaldehyde in an amount of 2,000 ppm, and formic acid in an amount of 20 ppm, and benzene in a (trioxane/benzene) ratio of 3/7, were added an antioxidant and an alkaline organic compound of the types and in the amounts shown in Table 1 to prepare a trioxane composition.

(16) The obtained trioxane composition was placed in a closed container made of SUS 304 having therein a nitrogen atmosphere, and stored at 30 C. for 2 weeks. After storing, formaldehyde and formic acid were extracted with water from the resultant trioxane composition, and then a formaldehyde content and a formic acid content of the extraction water were measured by a colorimetry method and titration. Further, an amount of the paraformaldehyde formed was quantitatively determined.

(17) Further, the trioxane composition obtained after being stored was subjected to distillation to obtain trioxane having a high purity, and then a polymerization test was conducted with respect to the obtained trioxane. The results are also shown in Table 1.

(18) TABLE-US-00001 TABLE 1 Comparative Example 1 Example 2 Example 3 Example 1 Antioxidant Type a-1 a-1 a-1 Amount (ppm) 50 50 51 0 Alkaline organic Type b-1 b-2 b-3 compound Amount (ppm) 0.5 0.5 0.5 0 Formaldehyde content after 2500 2700 2670 5000 storage (ppm) Formic acid content after 25 28 26 150 storage (ppm) Amount of paraformaldehyde ND ND ND 360 formed (ppm) Operation of distillation No problem No problem No problem Clogged purification Trioxane purity after distillation 99.9 99.9 99.9 purification (%) Formaldehyde content after 24 31 41 distillation purification (ppm) Formic acid content after 11 17 19 distillation purification (ppm) Polymerization test A A A

(19) The abbreviations used in Table 1 have the following meanings.

(20) Antioxidant:

(21) a-1) Triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 245; manufactured by BASF AG)

(22) a-2) 1,6-Hexanediol-bis[3(3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 259; manufactured by BASF AG)

(23) Alkaline organic compound:

(24) b-1) Triethanolamine

(25) b-2) Triphenylphosphine

(26) b-3) Zinc dimethyldithiocarbamate

(27) Polymerization test:

(28) A: the polymerization yield is 80% or more, no problem occurs; B: the polymerization yield is less than 80%, the reaction rate or molecular weight is lowered.

Examples 4 to 8 and Comparative Examples 2 to 11

(29) A uniform solution, which had been prepared from trioxane having a purity of 99.4% and containing water in an amount of 3,000 ppm, formaldehyde in an amount of 2,000 ppm, and formic acid in an amount of 20 ppm, and benzene in a ratio of 3/7, was subjected to distillation purification to obtain high-purity trioxane having a trioxane purity of 99.9% and containing formaldehyde and formic acid in respective amounts of 21 ppm and 9 ppm. To the resultant trioxane were added an antioxidant and an alkaline organic compound of the types and in the amounts shown in Tables 2 to 4 to prepare a trioxane composition.

(30) The obtained trioxane composition was placed in a closed container made of SUS 304 having therein a nitrogen atmosphere, and stored at 80 C. for 20 days. After storing, a formaldehyde content and a formic acid content of the resultant trioxane composition were measured by a colorimetry method and titration. Further, an amount of the paraformaldehyde formed was quantitatively determined. Further, using the trioxane composition obtained after being stored, a polymerization test was conducted. The results are also shown in Tables 2 to 4.

(31) TABLE-US-00002 TABLE 2 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Antioxidant Type a-1 a-1 a-2 a-1 a-1 a-1 Amount (ppm) 50 150 150 50 50 50 Alkaline organic Type b-1 b-1 b-1 b-1 b-5 b-6 compound Amount (ppm) 0.5 0.5 0.5 5 0.5 0.5 Formaldehyde content after 29 27 37 28 28 50 storage (ppm) Formic acid content after 27 26 28 26 29 31 storage (ppm) Amount of paraformaldehyde ND ND ND ND ND ND formed (ppm) Polymerization test A A A A A A

(32) TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Comparative Comparative Comparative Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Antioxidant Type a-1 a-1 a-2 Amount (ppm) 0 0 0 150 1000 150 Alkaline organic Type b-1 b-1 compound Amount (ppm) 0 0.5 50 0 0 0 Formaldehyde content after 500 480 470 60 60 120 storage (ppm) Formic acid content after 1900 1800 1750 50 50 45 storage (ppm) Amount of paraformaldehyde 39 26 17 ND ND ND formed (ppm) Polymerization test B B B A B A

(33) TABLE-US-00004 TABLE 4 Comparative Comparative Comparative Comparative Comparative Example 8 Example 9 Example 10 Example 11 Example 12 Antioxidant Type a-1 a-1 a-1 a-1 a-1 Amount (ppm) 50 50 50 50 50 Alkaline organic Type b-1 b-1 b-7 b-8 b-4 compound Amount (ppm) 20 50 0.5 0.5 0.5 Formaldehyde content after 29 29 140 170 70 storage (ppm) Formic acid content after 23 22 170 190 150 storage (ppm) Amount of paraformaldehyde ND ND 27 31 16 formed (ppm) Polymerization test B B A A A

(34) The abbreviations used in Tables 2 to 4 have the following meanings.

(35) Antioxidant:

(36) a-1) Triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 245; manufactured by BASF AG)

(37) a-2) 1,6-Hexanediol-bis[3(3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 259; manufactured by BASF AG)

(38) Alkaline organic compound:

(39) b-1) Triethanolamine

(40) b-2) Triphenylphosphine

(41) b-3) Zinc dimethyldithiocarbamate

(42) b-4) Triethylamine

(43) b-5) N,N-Diethylethanolamine

(44) b-6) N-Ethyldiethanolamine

(45) b-7) Bis(1,2,2,6,6-pentamethyl-4-piperidyl) cebacate

(46) b-8) Polycondensation product of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethyl-4-piperidine

(47) Polymerization test:

(48) A: the polymerization yield is 80% or more, no problem occurs; B: the polymerization yield is less than 80%, the reaction rate or molecular weight is lowered.

(49) As can be seen from Tables 1 to 4, the trioxane composition of the present invention can effectively suppress the quality deterioration of trioxane during the storage, and can be advantageously applied to the production of a polyacetal resin.

(50) The whole of the disclosure of Japanese Patent Application No. 2013-143759 is incorporated into the present specification by reference.

(51) All the documents, patent applications, and technical standards described in the present specification are incorporated into the present specification by reference to the same extent as that in the case where it is specifically and individually shown that each of the documents, patent applications, and technical standards is incorporated into the present specification by reference.