KR20130005695A - Method for polymerizing polyoxymethylene polymer - Google Patents

Abstract

PURPOSE: A manufacturing method of a polyoxymethylene is provided to efficiently deactivate a BF3-based polymerization catalyst by alkylated formamide acetal as a polymerization stopper, thereby being capable of suppressing degradation of molecular weight and thermal stability of a product polymer. CONSTITUTION: A manufacturing method of a polyoxymethylene comprises: a step of polymerization process using a BF3-based polymerization catalyst to prepare an oxymethylene homopolymer which consists of an oxymethylene unit indicated in chemical formula 1: -(CH2O)- and a copolymer in which the unit indicated in chemical formula 1 and a unit indicated in chemical formula 2: -[-(CX1X2)xO-]- are randomly bonded. After obtaining desired molecular weight, the polymerization stopped by adding alkylated formamide acetal as a polymerization stopper.

Description

Polymerization method for polyoxymethylene polymer {Method for polymerizing polyoxymethylene polymer}

The present invention relates to a method for producing a polyoxymethylene polymer, and more particularly, a method for producing a polyoxymethylene polymer having a low content of low molecular weight and excellent thermal stability by stopping a polymerization reaction using a new polymerization terminator. It is about.

Generally, polyoxymethylene resins are prepared by bulk polymerization, solution polymerization or suspension polymerization of trioxane alone or trioxane with cyclic ethers and / or cyclic acetals to prepare oxymethylene homopolymers or copolymers. Such a method is introduced in several prior documents including Japanese Patent Application Laid-open No. 36-14640, and is known in the art.

However, the polymer obtained by such bulk polymerization, solution polymerization or suspension polymerization is thermally unstable in itself, so in the case of the homopolymer, the end group is blocked by esterification or the like, and in the case of the copolymer, the unstable end group is decomposed. The polymer is stabilized by removal, and it is necessary to deactivate the catalyst to stop the polymerization reaction before such stabilization step. That is, if the catalyst remaining in the reaction product in the oxymethylene homopolymer and copolymer obtained by cation polymerization of trioxane or the like is not deactivated, depolymerization gradually occurs and the molecular weight of the polymer is significantly lowered, resulting in thermal instability.

In connection with such deactivation of the catalyst, US Patent No. 2989509 proposes the use of an aliphatic amine and a heterocyclic amine as a BF _3- based polymerization catalyst deactivator. However, when the catalyst is deactivated with the amine compound, a separate washing step is performed. The polymer is stabilized only by removing the amine compound again, for example, so that the molecular weight is not lowered during long term storage. In addition, if the amine compound is not removed from the polymer when the polymer is dissolved or melted (melted), depolymerization also occurs and molecular weight decreases. Therefore, the catalyst is removed from the polymer by sufficient washing operation after deactivating the catalyst with the amine compound. It is essential.

In addition, Japanese Patent Application Laid-Open No. 62-267311 uses a hindered amine compound to solve this problem in US Pat. No. 2989509 and the like, and performs polymerization without a separate washing operation. We are proposing a way to stop it. However, the compound proposed by this method has a low reactivity with the polymerization catalyst and thus has a catalyst deactivation effect only when used in excess, thus resulting in a cost burden. In addition, when using the sterically hindered amine compound there is a problem that causes long-term heat or regeneration of the physical properties and poor color.

The present invention is to provide a polyoxymethylene polymerization method capable of effectively deactivating the BF ₃ -based polymerization catalyst to stop the polymerization reaction to suppress the molecular weight and thermal stability of the resulting polymer.

In the present invention, an oxymethylene homopolymer composed of an oxymethylene unit represented by Formula 1 or a unit represented by Formula 1 and a unit represented by Formula 2 are randomly bonded by a polymerization process using a polymerization catalyst of a BF ₃ coordination compound. In the method for producing a polyoxymethylene polymer for producing a copolymer, a method for producing a polyoxymethylene polymer is provided in which an alkyl substituted formamide acetal is added as a polymerization terminator to stop a polymerization reaction after a desired molecular weight is obtained.

[Formula 1]

[Formula 2]

In Chemical Formulas 1 and 2, X ₁ and X ₂ may be the same or different from each other, and each of hydrogen, an alkyl group having 1 to 4 carbon atoms, but not all hydrogen, x is an integer of 2 to 6.

Preferably, the alkyl substituted formamide acetal is represented by the following Formula 5

[Chemical Formula 5]

R ₁ to R ₄ may be the same as or different from each other, and are each an alkyl group having 1 to 20 carbon atoms, and more preferably, in Formula 5, R ₁ to R ₄ are independently -CH ₃ or -CH. ₂ CH ₃ , -CH ₂ CH ₂ CH ₃ , -CH (CH ₃ ) ₂ , -CH ₂ -C (CH ₃ ) ₃ .

In addition, the alkyl substituted formamide acetal is preferably added in an amount of 0.01 to 50 mole times the BF ₃ coordination compound polymerization catalyst.

It is preferable to add the polymerization terminator after the homopolymer or copolymer has a molecular weight of 10,000 to 200,000 g / mol.

In addition, the alkyl-substituted formamide acetal polymerization terminator may be dissolved in an organic solvent and added, the organic solvent is benzene, toluene, xylene, n-hexane, n-heptane, cyclohexane, alcohol, chloroform, dichloromethane , 1,2-dichloroethane, acetone, methyl ethyl ketone.

And, the BF ₃ coordination compound polymerization catalyst is BF ₃ · OH ₂ , BF ₃ · OEt ₂ (Et represents an ethyl group), BF ₃ · OBu ₂ (Bu represents a butyl group), BF ₃ · CH ₃ CO ₂ H , may be a BF ₃ · PF ₅ · HF, at least one selected from the group consisting of BF ₃ -10- hydroxy-acetamide phenol.

When the polyoxymethylene is polymerized using the polymerization terminator according to the present invention, it is possible to effectively deactivate the polymerization catalyst after the polymerization, so that depolymerization does not occur, so that a polymer having a low molecular weight content and good thermal stability can be obtained.

In the present invention, in preparing an oxymethylene homopolymer or copolymer using a boron trifluoride (BF ₃ ) -based catalyst, a polyoxymethylene polymer is prepared by adding an alkyl substituted formamide acetal to terminate the polymerization reaction. It provides a method of polymerization.

Hereinafter, the present invention will be described in detail.

The polyoxymethylene polymerized by the present invention may be a homopolymer composed of oxymethylene units represented by the following Chemical Formula 1 or a copolymer in which units of the Chemical Formula 1 and units of the Chemical Formula 2 are randomly bonded.

Where

X ₁ and X ₂ may be the same or different from each other, and are each hydrogen, an alkyl group having 1 to 4 carbon atoms (both X ₁ and X ₂ are not hydrogen), and x is an integer of 2 to 6;

The polyoxymethylene is not particularly limited, but preferably has a molecular weight in the range of 10,000 to 200,000 g / mol.

The oxymethylene homopolymer may be prepared by polymerizing formaldehyde or a cyclic oligomer thereof, that is, trioxane, and the oxymethylene copolymer in which the unit of Formula 1 and the unit of Formula 2 are combined with formaldehyde or a cyclic oligomer thereof It can be obtained by random copolymerization of the cyclic ether represented by the following formula (3) or the cyclic formal represented by the following formula (4):

In the above formulas (3) and (4)

X ₃ , X ₄ , X ₅ and X ₆ may be the same or different from each other, each is hydrogen or an alkyl group having 1 to 4 carbon atoms, may be bonded to the same carbon atom or to another carbon atom, n and m are each It is an integer of 2-6.

Among the comonomers used in the random copolymerization, cyclic ethers include ethylene oxide, propylene oxide, butylene oxide, phenylene oxide, and the like, and cyclic formales include 1,3-dioxolane, diethylene glycol formal, 1 , 3-propanediol formal, 1,4-butanediol formal, 1,3-dioxepan formal, 1,3,6-trioxokan etc. are mentioned. Preferably, one or more monomers selected from monomers such as ethylene oxide, 1,3-dioxolane and 1,4-butanediol formal may be used, and these monomers may be added to trioxane or formaldehyde as main monomers. The oxymethylene copolymer can be obtained by addition and random copolymerization using Lewis acid as a catalyst, whereby the copolymer obtained has a melting point of at least 150 ° C. and at least two bonded carbon atoms in the main chain.

In the oxymethylene copolymer, the ratio of the oxymethylene bond structure to the oxymethylene repeating unit is in the range of 0.05 to 50 mole times, preferably in the range of 0.1 to 20 mole times.

Polymerization catalysts used for the polymerization of the oxymethylene polymer include BF ₃ · OH ₂ , BF ₃ · OEt ₂ (Et means ethyl group), BF ₃ · OBu ₂ (Bu means butyl group), and BF ₃ · _{CH 3 CO 2 H, BF 3} · PF 5 · HF, BF ₃ and the like -10- hydroxy-acetamide phenol, preferably using a BF ₃ · OEt ₂ and BF ₃ · OBu _2. The added amount of the polymerization catalyst relative to 1 mol of trioxane 2 × 10 ^-6 to 2 × 10 ^- preferably in the range of ² molar.

The polymerization may be carried out in the form of bulk polymerization, suspension polymerization or solution polymerization, the temperature during the polymerization may be carried out in the range of 0 to 100 ℃, preferably 20 to 80 ℃.

In the polymerization reaction of polyoxymethylene, an alkyl substituted phenol or an ether may be used as a chain transferring agent, and particularly preferably an alkyl ether such as dimethoxymethane or the like.

When the molecular weight of polyoxymethylene is 10,000-200,000 g / mol by the said polymerization reaction, a polymerization terminator is added and the polymerization reaction is stopped. As the polymerization terminator, the present invention uses an alkyl substituted formamide acetal having a structure of the following formula (5).

Where

R ₁ to R ₄ may be the same or different from each other, and each is an alkyl group having 1 to 20 carbon atoms, more preferably -CH ₃ , -CH ₂ CH ₃ , -CH ₂ CH ₂ CH ₃ , -CH (CH ₃ ) ₂ , -CH ₂ -C (CH ₃ ) ₃ It may be selected from the group consisting of.

In the polymerization of the polyoxymethylene of the present invention, the alkyl-substituted formamide acetal of the formula (5) used as a polymerization terminator may be added as it is or dissolved in an organic solvent.

At this time, organic solvents that can be used include aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as n-hexane, n-heptane and cyclochlorohexane, alcohols such as methanol, chloroform, dichloromethane and 1,2- Halogenated hydrocarbons such as dichloroethane and the like, ketones such as acetone, methyl ethyl ketone and the like.

The addition amount of the polymerization terminator according to the present invention is good in the amount of a range in which the same number of nitrogen atoms are added to the number of boron atoms in the boron trifluoride coordination compound of the used polymerization catalyst, specifically, the boron trifluoride coordination compound as the polymerization catalyst 0.01 to 50 mole times, preferably 0.05 to 10 mole times. If the amount is less than the above range, the deactivation effect on the polymerization catalyst is reduced and heat stability is not preferable. If the amount is more than the above range, the polymer may be degraded or cause discoloration. It is preferable to use in the said range. The addition amount can be suitably adjusted according to the target heat stability degree within the said range.

By adding the polymerization terminator proposed in the present invention to stop the polyoxymethylene polymerization reaction, it is possible to effectively deactivate the polymerization catalyst after the polymerization and to suppress depolymerization, so that the content of low molecular weight and good thermal stability is low. Methylene polymers can be obtained.

Example

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples. However, the following examples are not intended to limit the present invention.

The measuring method of the physical properties described in the following Examples is as follows.

1) Weight reduction rate of the polymer (heat stability)

The thermal stability was evaluated by measuring the weight loss rate after treating the polymer for 30 minutes at a vacuum pressure of 10 mmHg and a temperature of 222 ± 2 ° C. The smaller the weight reduction value, the better the thermal stability.

2) melt index

The weight of the polymer sample extruded for 10 minutes at an orifice of constant internal diameter at a temperature of 190 ° C. and a load of 2.16 kg was measured. This value is a measure for evaluating the depolymerization rate of the polymer. The rate is high.

3) CH ₂ O generation amount

About 2 g of polyoxymethylene resin pellets were taken, and CH ₂ O gas generated by heating to 222 ° C. while adding nitrogen was collected in ice water, and the color development was analyzed by UV spectrophotometer to measure the amount of CH ₂ O generated. Higher values indicate poor thermal stability.

Example 1

After maintaining a 600cc small polymerizer at 50 ° C, 500 g of trioxane and 20.0 g of 1,3-dioxolane, a comonomer, were injected using a metering device, and BF _{3 was used} as a polymerization catalyst. 0.06 g of O (Et) ₂ (78 ppm relative to trioxane) was added to the polymerizer. Approximately 15 minutes after the addition of the polymerization catalyst, N, N-dimethyl formamide acetal (DMF DMA) as a polymerization terminator (R ₁ to R ₄ = -CH ₃ in Formula 5) 0.052 g (1.0-fold molar relative to the polymerization catalyst) was dissolved in 0.5 g of benzene and added, and after 10 minutes, the reaction was completed to obtain the resulting polymer.

The thermal stability, the melt index, and the amount of CH ₂ O generated above were measured for the obtained polymer, and the results are shown in Table 1.

Examples 2 to 5

DMF DMA was used differently at 0.025 g (0.5 molar moles for the polymerization catalyst), 0.078 g (1.5 molar moles for the polymerization catalyst), 0.104 g (2.0 molar moles for the polymerization catalyst), 0.208 (4.0 molar moles for the polymerization catalyst) A polymer was obtained in the same manner as in Example 1, except that thermal stability, melt index, and CH ₂ O generation amount of the obtained polymer were measured, and the results are shown in Table 1.

Example 6

A polymer was obtained in the same manner as in Example 1, except that 12.5 g of ethylene oxide was used instead of 1,3-dioxolane as a comonomer and 0.052 g of DMF DMA (1.0-fold molar relative to the polymerization catalyst) was used. The thermal stability, the melt index, and the amount of CH ₂ O generated for the obtained polymer were measured, and the results are shown in Table 1.

Example 7

N, N-dimethyl formamide diehthyl acetal (DMF DEA) (R ₁ and R ₂ = -CH ₂ CH ₃ in the structure of Formula 5, R ₃ and R _{4 as} polymerization terminator) = -CH ₃ ) The polymer was obtained in the same manner as in Example 1 except that 0.064 g (1.0-fold molar amount of the polymerization catalyst) was used, and thermal stability, melt index, and CH ₂ O generation amount of the obtained polymer were determined. The results are shown in Table 1 below.

Example 8

N, N-dimethyl formamide dineopentyl acetal (DMF DNA) (R ₁ and R ₂ = -CH ₂ -C (CH ₃ ) ₂ in the structure of Formula 5) R ₃ and R ₄ = -CH ₃ ) The polymer was obtained in the same manner as in Example 1 except that 0.100 g (1.0-fold molar amount of the polymerization catalyst) was used, and the thermal stability, melt index and CH ₂ O generation was measured and the results are shown in Table 1.

Example 9

Polymer was obtained in the same manner as in Example 1, except that 12.5 g of ethylene oxide was used instead of 1,3-dioxolane and 0.100 g of DMF DNA (1.0-fold molar relative to the polymerization catalyst) was used as a comono. Thermal stability, melt index, and CH ₂ O generation amount for the polymer were measured and the results are shown in Table 1.

Comparative Example 1

A polymer was obtained in the same manner as in Example 1 except that a polymerization terminator was not used. The thermal stability, the melt index, and the amount of CH ₂ O generated for the obtained polymer were measured, and the results are shown in Table 1.

Comparative Example 2

Polymer was obtained in the same manner as in Example 1, except that 0.014 g of triethylamine (5.0 times mole relative to the polymerization catalyst) was used instead of N, N-dimethyl formamide acetal as a polymerization terminator, and the heat of the obtained polymer was The stability, melt index and the amount of CH ₂ O generated were measured and the results are shown in Table 1.

Comparative Example 3

A polymer was obtained in the same manner as in Comparative Example 2, except that 0.170 g of triethylamine (60 times mole relative to the polymerization catalyst) was used as a polymerization terminator, and thermal stability, melt index, and CH ₂ O generation amount of the obtained polymer were measured. The results are shown in Table 1.

Comparative Example 4

Example 1 except that 1.105 g of TINUVIN765 (sterically hindered amine compound manufactured by Ciba-geigy) was used instead of N, N-dimethyl formamide acetal as a polymerization terminator (5.0 times with respect to the polymerization catalyst). The polymer was obtained by the same method as described above. The thermal stability, the melt index, and the amount of CH ₂ O generated for the obtained polymer were measured, and the results are shown in Table 1.

Comparative Example 5

A polymer was obtained in the same manner as in Comparative Example 4 except that 0.170 g of TINUVIN765 (0.8-fold mole relative to the polymerization catalyst) was used as a polymerization terminator, and thermal stability, melt index, and CH ₂ O generation amount of the obtained polymer were measured and measured. The results are shown in Table 1.

division Comonomer Polymerization Stopping Agent
(Molar multiples for the polymerization catalyst) weight
Decrease (%) Melt Index (g / 10min) CH ₂ O
Generation amount (ppm) room
city
Yes One 1,3-dioxolane DMF DMA 0.052g (1.0x) 3.8 9.5 450 2 1,3-dioxolane DMF DMA 0.025g (0.5x) 4.0 9.8 470 3 1,3-dioxolane DMF DMA 0.078g (1.5x) 3.5 9.5 430 4 1,3-dioxolane DMF DMA 0.104g (2.0x) 3.5 9.5 400 5 1,3-dioxolane DMF DMA 0.208g (4.0x) 3.4 9.5 400 6 Ethylene oxide DMF DMA 0.052g (1.0x) 3.5 9.4 450 7 1,3-dioxolane DMF DEA 0.064 g (1.0 times) 3.7 9.5 430 8 1,3-dioxolane 0.100 g (1.0 times) of DMF DNA 4.0 9.6 430 9 Ethylene oxide 0.100 g (1.0 times) of DMF DNA 4.0 9.5 430 ratio
School
Yes One 1,3-dioxolane - 15.0 53.0 2,500 2 1,3-dioxolane 0.014 g (5.0 times) of triethylamine 10.5 18.5 1,700 3 1,3-dioxolane 0.170 g (60.0 times) of triethylamine 10.3 19.0 1,750 4 1,3-dioxolane TINUVIN765 1.105g (5.0x) 4.8 10.0 600 5 1,3-dioxolane TINUVIN765 0.170 g (0.8 times) 9.5 14.0 1,200

From Table 1, the oxymethylene polymer prepared using alkylated formamide acetal as a polymerization terminator according to the present invention is not using a polymerization terminator or a triethylethylamine compound as in Comparative Example. Compared with the obtained oxymethylene polymer, the thermal stability is remarkably excellent, the depolymerization rate is very low, and the generation amount of CH ₂ O is also very low.

Claims (8)

An oxymethylene homopolymer composed of oxymethylene units represented by Formula 1 or a copolymer in which units represented by Formula 1 and units represented by Formula 2 are randomly bonded by a polymerization process using a polymerization catalyst of a BF ₃ coordination compound In the polyoxymethylene polymer production method for producing a polyoxymethylene polymer, after the desired molecular weight is obtained, the alkylated formamide acetal (alkylated formamideacetal) is added as a polymerization terminator to stop the polymerization reaction.
[Formula 1]

(2)

In Chemical Formulas 1 and 2, X ₁ and X ₂ may be the same or different from each other, and each of hydrogen, an alkyl group having 1 to 4 carbon atoms, but not all hydrogen, x is an integer of 2 to 6.
According to claim 1, wherein the alkyl substituted formamide acetal is represented by the formula (5)
[Chemical Formula 5]

Is indicated by
Herein, R ₁ to R ₄ may be the same or different from each other, and a polyoxymethylene polymer production method, characterized in that each of the alkyl group having 1 to 20 carbon atoms.
The method according to claim 2, wherein in Formula 1 R ₁ to R ₄ are independently -CH ₃ , -CH ₂ CH ₃ , -CH ₂ CH ₂ CH ₃ , -CH (CH ₃ ) ₂ , -CH ₂ -C ( CH ₃ ) ₃ polyoxymethylene polymer production method characterized in that it is selected from the group consisting of.
The method of claim 1, wherein the alkyl-substituted formamide acetal is added in an amount of 0.01 to 50 mole times the BF ₃ coordination compound polymerization catalyst.
The method of claim 1, wherein the BF ₃ coordination compound polymerization catalyst is BF ₃ · OH ₂ , BF ₃ · OEt ₂ (Et represents an ethyl group), BF ₃ · OBu ₂ (Bu represents a butyl group), BF ₃ · CH _{3 CO 2 H, BF 3 ·} PF 5 · HF, polyoxypropylene method methylene polymer is at least one selected from BF ₃ -10- hydroxy group consisting of acetamido phenol.
The method for producing a polyoxymethylene polymer according to any one of claims 1 to 5, wherein the alkyl substituted formamide acetal polymerization terminator is dissolved in an organic solvent and added.
The method of claim 6, wherein the organic solvent is a group consisting of benzene, toluene, xylene, n-hexane, n-heptane, cyclohexane, alcohol, chloroform, dichloromethane, 1,2-dichloroethane, acetone, methyl ethyl ketone Method for producing a polyoxymethylene polymer, characterized in that at least one organic solvent selected from.
The method for producing a polyoxymethylene polymer according to any one of claims 1 to 5, wherein the polymerization terminator is added after the homopolymer or copolymer has a molecular weight of 10,000 to 200,000 g / mol.