JP2001031672A - Method for preserving trioxane, oxymethylene copolymer obtained by polymerizing the trioxane and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preserve molten trioxane in a good state by adding a specific hindered amine-based compound to the trioxane. SOLUTION: Trioxne is preserved by adding preferably 0.5-50 ppm of a hindered amine-based compound expressed by the formula (R1 is H or a 1-30C monovalent organic residue; R2 to R5 are each a 1-5C alkyl; n is >=1: R6 is a n-valent organic residue), [preferably bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate]. Further, a sterically hindered phenol-based compound, preferably triethylene glycol bis[3-(3-t-butyl-5- methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4- hydoxyphenyl)propionate] are preferably added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The trioxane has a melting point of 64 ° C.
Is an important substance used mainly as a raw material for oxymethylene polymers or copolymers and as an industrial product. Industrially, formaldehyde is used as a raw material in a generally known manner. It is synthesized using the sulfuric acid, cation resin, zeolite or the like used as a catalyst. The present invention relates to a method for storing trioxane and a trioxane composition.

[0002]

2. Description of the Related Art Trioxane is an unstable substance against oxygen. Particularly, when stored in a molten state, trioxane is oxidized even by the presence of a very small amount of oxygen to significantly increase the formic acid content and formaldehyde content. To increase. Further, it is also known that a part of trioxane is polymerized to form polyoxymethylene due to the presence of a trace amount of impurities when the molten trioxane is cooled and solidified. Further, even when trioxane contains a trace amount of a sulfur compound presumably due to sulfuric acid, which is a catalyst for synthesizing trioxane, trioxane may be polymerized to form polyoxymethylene.

[0003] It has been recognized that when these are polymerized as a raw material of an oxymethylene copolymer, they have a considerable adverse effect on the polymerization reaction and also on the quality of the polymer.

Therefore, various methods have been proposed for preserving trioxane. For example,
No. 43514 describes adding an organic trivalent phosphorus compound to trioxane. In addition, Japanese Patent Publication No. 55-12025 discloses that trioxane
The addition of a thiocarbamoyl compound is described. Further, JP-A-7-242652 discloses that a sterically hindered phenol may be added to a cyclic formal for the purpose of preventing deterioration of the cyclic formal known as a raw material (co) monomer of the oxymethylene copolymer. Has been described.

[0005]

However, when an organic trivalent phosphorus compound or a thiocarbamoyl compound is added to trioxane, it has an effect of suppressing polyoxymethylene generated when trioxane is cooled and solidified. The effect of suppressing the formation of formic acid or formaldehyde is insufficient.

On the other hand, when only a phenolic antioxidant such as sterically hindered phenol is added alone, it is effective in preventing an increase in formic acid and formaldehyde, but it is formed by cooling and solidifying molten trioxane. When oxymethylene is remelted, it precipitates as a white floc and adheres to the pipe or inside of the dissolution tank, causing clogging, or when trioxane contains trace amounts of sulfur compounds, the sulfur compounds There is a problem that adversely affects the operation of the apparatus, for example, the polymerized polyoxymethylene causes clogging.

Accordingly, an object of the present invention is to provide a method for preserving trioxane, particularly in a molten state, in a good state and a trioxane composition excellent in preservability. As a result, they found that the addition of a hindered amine compound was effective, leading to the present invention.

[0008]

That is, the present invention relates to a method for preserving trioxane, which comprises adding trioxane to a compound represented by the general formula (I):

[0009]

Embedded image (Wherein, R ₁ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R _{2 to} R ₅ represent an alkyl group having 1 to ₅ carbon atoms. N is an integer of 1 or more, and R ₆ is an n-valent organic residue.) A method for preserving trioxane, which comprises adding a hindered amine compound represented by the formula: .

Further, the present invention relates to a method for preparing trioxane, wherein

[0011]

Embedded image (Wherein, R ₁ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R _{2 to} R ₅ represent an alkyl group having 1 to ₅ carbon atoms. N is an integer of 1 or more, and R ₆ is an n-valent organic residue.) Is a trioxane composition to which a hindered amine compound represented by the following formula (1) is added.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The hindered amine compounds used in the present invention include the following compounds.

[0014]

Embedded image

[0015]

Embedded image

[0016]

Embedded image

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image

[0020]

Embedded image

[0021]

Embedded image

[0022]

Embedded image

[0023]

Embedded image Among these hindered amine compounds, bis (1,2,2,6,6) are particularly effective in preventing the increase of formic acid and formaldehyde and of polyoxymethylene generated during solidification of molten trioxane. -Pentamethyl-4-piperidyl) sebacate or bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate is preferably used.

In the present invention, the amount of the hindered amine compound added is generally 5
In order to keep the polymerization reaction for at least one day and then to carry out the polymerization reaction favorably, the amount is preferably 0.5 to 50 ppm, particularly preferably 1 to 20 ppm, based on trioxane.

The hindered amine compound of the present invention may be added as it is, or may be added as a solution of an organic solvent in order to promote mixing with trioxane. As the organic solvent at that time, benzene, toluene,
Aromatic hydrocarbons such as xylene, n-hexane, n-
Examples include aliphatic hydrocarbons such as heptane and cyclohexane, alcohols such as methanol and ethanol, halogenated hydrocarbons such as chloroform, dichloromethane and 1,2-dichloroethane, and ketones such as acetone and methyl ethyl ketone.

The hindered amine compound in the present invention effectively acts on trioxane containing a sulfur compound.

In the present invention, the use of a hindered amine compound together with a sterically hindered phenol compound can further suppress the formic acid generation rate. Such sterically hindered phenolic compounds include triethylene glycol-bis [3- (3-t-butyl-
5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate], octadecyl-3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate, N, N-hexamethylenebis (3,5-dibutyl-4-hydroxy-hydrocinnamamide), 1,3,5
-Trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene, tris-
(3,5-di-t-butyl-4-hydroxybenzyl)
-Isocyanurate, isooctyl-3- (3,5-di-butyl-4-hydroxyphenyl) propionate and the like. In particular, triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate] is preferably used.

The amount of the sterically hindered phenolic compound added is generally 0.5 to 500 ppm based on trioxane in order to maintain a good storage state of trioxane for 5 days or more, and then to carry out the polymerization reaction well. It is preferably, particularly preferably 1 to 100 ppm.

The trioxane stored according to the present invention is used as it is in a polymerization reaction using a boron trifluoride-based catalyst such as a boron trifluoride-based catalyst or a complex compound thereof, and provides a high-yield, high-quality polyoxymethylene polymer. Coalescence can be obtained. The boron trifluoride-based catalyst is preferably at least one selected from the group consisting of boron trifluoride, boron trifluoride hydrate, and an organic compound containing boron trifluoride and an oxygen atom or a sulfur atom.

Specifically, a mixture of the trioxane composition and the cyclic ether stored by the above method is subjected to bulk polymerization using a boron trifluoride-based catalyst, and a catalyst deactivator is added to the obtained polymer. Or, after washing and removing the catalyst,
Heating above the melting point of the copolymer gives a polyoxymethylene copolymer.

As the catalyst deactivator added to the polymer, an amine compound is preferable, and a hindered amine compound is particularly preferable. As the hindered amine in this case, those used for preservation of the above-mentioned trioxane can be used as they are, and preferable specific examples are also the same as described above. Also,
The amine compound may be added as it is,
It may be added as a solution of an organic solvent in order to enhance the polymerization termination effect. As the organic solvent at that time, benzene, toluene, aromatic hydrocarbons such as xylene, n-hexane, n-heptane, aliphatic hydrocarbons such as cyclohexane, alcohols such as methanol and ethanol, chloroform, dichloromethane, Halogenated hydrocarbons such as 1,2-dichloroethane and ketones such as acetone and methyl ethyl ketone are used.

The amine compound of the present invention is preferably added in an amount equal to or greater than the number of boron atoms of the boron trifluoride-based catalyst in the polymerization catalyst used. Even if the number of nitrogen atoms is smaller than the number of boron atoms, the catalyst deactivating effect can be seen, but the thermal stability of the obtained polymer is slightly reduced, so the amount of addition is adjusted according to the intended degree of thermal stability. There is a need.

The method for washing and removing the catalyst is carried out by a known method. That is, this is a method in which the polyoxymethylene copolymer is added to water or an organic solvent containing a basic substance, the catalyst is deactivated, and the polyoxymethylene copolymer is separated by filtration.
Examples of the basic substance include an alkali metal or alkaline earth metal hydroxide, an inorganic weak acid salt, an organic acid salt and the like. Further, amine compounds such as ammonia, triethylamine and triptylamine are also used.

The polyoxymethylene copolymer produced according to the present invention may contain a filler, a fibrous reinforcing agent, an ultraviolet absorber, a mold release agent, a nucleating agent, a plasticizer, and the like as long as the effects of the present invention are not impaired. Additives such as a coloring agent and an adhesion aid can be optionally contained.

[0035]

Next, the present invention will be described with reference to Examples and Comparative Examples. The analysis of formic acid and formaldehyde in trioxane and the thermal decomposition rate were carried out by the following methods.

Formic acid: Formic acid in trioxane was measured by a neutralization titration method in which trioxane was added to an acetone solvent and then 0.01 N NaOH was added. An automatic potentiometric titrator was used for the titration.

Formaldehyde: Formaldehyde in trioxane was measured using a gas chromatograph. The instrument is Shimadzu GC-14B and the column is TSR-
1. The column temperature was measured at 100 ° C. using helium as a carrier gas.

Thermal decomposition rate (Kx): Kx is 6 at x ° C.
It means the decomposition rate when left for 0 minutes, and means a thermobalance device (Du).
Using a thermal analyzer 1090/1091 manufactured by Pont, about 10 mg of the sample was allowed to stand at x ° C. in an air atmosphere, and determined by the following equation.

Kx = (W0−W1) × 100 / W0 (%) Here, W0 means the sample weight before heating, and W1 means the sample weight after heating. MI value (melt index): 190 ° C., 216 according to JIS K7210
It was measured at 0 g.

The additives used in the examples are shown below. HA-1: bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate HA-2: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate HA-3: tri Ethanolamine HP-1: triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] HP-2: 1,6-hexanediol-bis [3- (3, 5-Di-t-butyl-4-hydroxyphenyl) propionate] Example 1 In a closed autoclave having a jacket through which a heat medium can pass and a stirring blade, 3 ppm of formic acid as an impurity,
5.1 kg of molten trioxane containing 5 ppm of formaldehyde at 70 ° C. was added thereto, and 5 ppm of HA-1 was further added. In the presence of air, hot water at 70 ° C. was passed through the jacket and stored. Five days later, trioxane contained 7 ppm of formic acid and 8 ppm of formaldehyde, and the formation of formic acid and formaldehyde by melt storage was slight. Next, 100 g of this trioxane was sampled, cooled and solidified to 20 ° C., left to stand for 2 hours, the sample was placed in an oven at 70 ° C., and heated and melted again. The generated flocculent polyoxymethylene white precipitate was filtered off, washed with acetone, dried and weighed. The amount of sediment was small and was 4.3 mg.

Further, with respect to 5.0 kg of molten trioxane in the autoclave, 1,3-dioxolan was added to 172
g, 3.5 g of methylal and 6.6 g of a benzene solution containing 0.6 g of boron trifluoride / diethyl etherate, and the mixture was stirred at 40 rpm while passing hot water at 70 ° C. After about 1.5 minutes the reaction started and the internal temperature rose. The temperature rose to about 110 ° C., but stirring was continued for 10 minutes. The reaction mixture was pulverized to obtain a white powdery polymer. To this polymer was added 192 g of a benzene solution containing 10 g of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, and the mixture was stirred and mixed with a 10 L ribbon blender for 5 minutes to polymerize. The reaction was stopped. Further, 24 g of triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate) and 4.8 g of calcium stearate were added, and the mixture was stirred and mixed for 3 minutes. Using a twin-screw 45 mmφ extruder
The mixture was melt extruded at a temperature of 5 ° C. and a vent pressure of 5 mmHg. The resulting polymer was extruded into strands and pelletized with a cutter. The amount of the obtained polymer was 4.8 kg, and the yield was 92.0%, which was a high yield. Place the pellets in a hot air oven at 80
After drying at 5 ° C. for 5 hours, the MI value was 9.5, and the thermal decomposition rate was K230.
Was 2.2%, and the quality was good. Table 1 shows the results. Example 2 An experiment was performed in the same manner as in Example 1 except that 8 ppm of HA-1 was added to trioxane. After 5 days, 6 ppm of formic acid and 7 ppm of formaldehyde in trioxane
And the amount of formation was slight, and the amount of white precipitate in 100 g of trioxane was as small as 3.9 mg. Also. The MI value of the obtained polymer was 9.6, K230 was 2.0%, and the yield was 9
0.5%, a high quality polymer was obtained in high yield. Example 3 In the same manner as in Example 1, HA-
2 was added to 8 ppm, and the experiment was performed. After 5 days, 7 ppm of formic acid and 9 ppm of formaldehyde in trioxane
And the amount produced was small, and the amount of white precipitate in 100 g of trioxane was as small as 4.2 mg. The MI value of the obtained polymer was 9.9, the K230 was 2.4%, and the yield was 9%.
0.0%, a high quality polymer was obtained in high yield. Example 4 In the same manner as in Example 1, HA-
1 was added to 8 ppm, and HP-1 was added to 55 ppm, and the experiment was performed. Five days later, the amount of formic acid in trioxane was 5 ppm, and the amount of formaldehyde was 6 ppm, which was very small. The amount of white precipitate in 100 g of trioxane was as small as 5.1 mg. The MI value of the obtained polymer was 8.8 and K230
Was 2.2% and the yield was 91.2%. A high quality polymer was obtained in a high yield. Example 5 In the same manner as in Example 1, HA-
1 was added to 8 ppm, and HP-2 was added to 55 ppm, and the experiment was performed. After 5 days, the amount of formic acid in trioxane was 6 ppm and the amount of formaldehyde in 6 ppm was small, and the amount of white precipitate in 100 g of trioxane was as small as 5.5 mg. The MI value of the obtained polymer was 9.0 and K230
Was 2.0% and the yield was 90.8%, and a high quality polymer was obtained in a high yield. Comparative Example 1 An experiment was performed in the same procedure as in Example 1 using trioxane to which neither the hindered amine compound nor the sterically hindered phenol was added. Five days later, trioxane contained 215 ppm of formic acid and 350 ppm of formaldehyde.
ppm and production increased significantly. The amount of white precipitate in 100 g of trioxane also increased to 56 g. The MI value of the obtained polymer was 17.0, the K230 was 20.3%, the yield was 85.1%, and the polymer quality was poor. Comparative Example 2 An experiment was performed in the same procedure as in Example 1 except that 55 ppm of HP-1 was added to the trioxane. Five days later, the formic acid content in trioxane was 98 ppm, and the formaldehyde content was 203 ppm. The amount of white precipitate in 100 g of trioxane also increased to 43 g. The MI value of the obtained polymer was 15.1 and the K230 was 28.8.
%, The yield was 82.4%, and the polymer quality was poor. Comparative Example 3 An experiment was performed in the same procedure as in Example 1, except that 55 ppm of HP-2 was added to the trioxane. Five days later, the formic acid content in trioxane was 110 ppm, and the formaldehyde content was 189 ppm. Further, the amount of white precipitate in 100 g of trioxane also increased to 49 g.
The MI value of the obtained polymer was 18.1 and the K230 was 29.2.
%, The yield was 81.1%, and the polymer quality was poor. Comparative Example 3 5 ppm of HA-3 was added to trioxane,
An experiment was performed in the same procedure as in Example 1. After 5 days, formic acid in trioxane was 78 ppm, and formaldehyde was 66 ppm.
ppm and production increased significantly. The amount of white precipitate in 100 g of trioxane also increased to 32 g. The MI value of the obtained polymer was 14.3, the K230 was 19.8%, the yield was 86.0%, and the polymer quality was poor.

[0042]

[Table 1] From the above results, it is clear that the present invention is an excellent method for preserving trioxane to suppress the formation of formic acid, formaldehyde and white precipitate in trioxane and to obtain a high quality polymer.

[0043]

According to the method for storing trioxane,
By adding the hindered amine compound, it was possible to prevent an increase in formic acid and formaldehyde, and the formation of polyoxymethylene during solidification of molten trioxane. There is no clogging in the piping and inside of the melting storage tank, which is significant in terms of stabilizing the process of the production equipment.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kim Fu-soo, Gyeongsangbuk-do, South Korea ▲ Turtle ▼ Oe-cho, Songjeong-dong Hansin apartment, 105, 1302 (72) Inventor Masaki Kunitomi 9 Oecho, Minato-ku, Nagoya-shi, Aichi 1 Toray Industries, Inc. Nagoya Office (72) Inventor Daisuke Ogawa 9 Toe, Oe-cho, Minato-ku, Nagoya City, Aichi Prefecture 1 Toray Industries Nagoya Office (72) Inventor Yoshiyuki 9 Oemachi, Minato-ku, Nagoya City, Aichi Prefecture Address No. 1 Toray Industries, Inc. Nagoya Office F-term (reference) 4C022 PA07 4J032 AA05 AA34 AB06 AC03 AC13 AC18 AE02 AE14

Claims (11)

[Claims] In the preservation of trioxane, trioxane is represented by the general formula (I): (Wherein, R ₁ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R _{2 to} R ₅ represent an alkyl group having 1 to ₅ carbon atoms. N represents an integer of 1 or more, and R ₆ represents an n-valent organic residue.) A method for preserving trioxane, which comprises adding a hindered amine compound represented by the formula: 2. The method for preserving trioxane according to claim 1, wherein the amount of the hindered amine compound is 0.5 to 50 ppm based on trioxane. 3. The method for preserving trioxane according to claim 1, wherein the amount of the hindered amine compound is 1 to 20 ppm based on trioxane. 4. The method according to claim 1, wherein the hindered amine compound is bis (1,
2,2,6,6-pentamethyl-4-piperidyl) sebacate or bis (2,2,6,6-tetramethyl-
The method for preserving trioxane according to any one of claims 1 to 3, which is 4-piperidyl) sebacate. 5. The method for preserving trioxane according to claim 1, wherein a sterically hindered phenol compound is added. 6. The sterically hindered phenolic compound is triethylene glycol-bis [3- (3-t-butyl-5-
Methyl-4-hydroxyphenyl) propionate],
Or 1,6-hexanediol-bis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate]. The method for preserving trioxane according to claim 5, wherein 7. A compound represented by the above general formula (I): (Wherein, R ₁ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R _{2 to} R ₅ represent an alkyl group having 1 to ₅ carbon atoms. N represents an integer of 1 or more, and R ₆ represents an n-valent organic residue.) A trioxane composition obtained by adding a hindered amine compound represented by the formula: 8. The trioxane composition according to claim 7, wherein a sterically hindered phenol compound is further added to trioxane. 9. A mixture of the trioxane composition according to claim 7 or 8 and a cyclic ether, comprising: boron trifluoride, boron trifluoride hydrate, and an organic compound containing boron trifluoride and an oxygen atom or a sulfur atom. A method for producing an oxymethylene copolymer, comprising performing bulk polymerization in the presence of at least one polymerization catalyst selected from the group consisting of: adding a catalyst deactivator, or washing and removing the catalyst after the polymerization is completed. . 10. The catalyst deactivator according to the above general formula (I) (Wherein, R ₁ represents a hydrogen atom or a monovalent organic residue having 1 to 30 carbon atoms, and R _{2 to} R ₅ represent an alkyl group having 1 to ₅ carbon atoms. N is an integer of 1 or more, and R ₆ is an n-valent organic residue.) A hindered amine compound represented by the following formula: A method for producing a polymer. 11. An oxymethylene copolymer produced by the method according to claim 9 or 10.