WO2024101270A1 - Method for producing polyacetal copolymer - Google Patents

Method for producing polyacetal copolymer Download PDF

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WO2024101270A1
WO2024101270A1 PCT/JP2023/039611 JP2023039611W WO2024101270A1 WO 2024101270 A1 WO2024101270 A1 WO 2024101270A1 JP 2023039611 W JP2023039611 W JP 2023039611W WO 2024101270 A1 WO2024101270 A1 WO 2024101270A1
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acid
polyacetal copolymer
carbonate
integer
carboxylate
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悠平 細井
栄次 増田
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ポリプラスチックス株式会社
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  • the present invention relates to a method for producing a polyacetal copolymer.
  • Polyacetal copolymers have an excellent balance of mechanical properties, chemical resistance, and sliding properties, and are easy to process, making them widely used as engineering plastics, primarily in electrical and electronic components, automotive parts, and various other machine parts.
  • Polyacetal copolymers are copolymers in which trioxane is the main monomer and a compound that can be copolymerized with trioxane is used as a comonomer.
  • a known method for producing polyacetal copolymers is cationic copolymerization in which trioxane is the main monomer and a cyclic ether and/or cyclic formal having at least one carbon-carbon bond is used as a comonomer.
  • cationic active catalysts used in copolymerization boron trifluoride or a coordination compound of boron trifluoride and an organic compound, such as an ether, is the most common polymerization catalyst for trioxane as the main monomer and is widely used industrially.
  • polymerization catalysts such as boron trifluoride compounds require a relatively large amount of catalyst (for example, 40 ppm or more relative to the total monomers) for polymerization. This makes it difficult to perform sufficient catalyst deactivation treatment after polymerization, and even if the catalyst is deactivated, problems such as substances derived from the catalyst remaining in the copolymer and promoting decomposition of the copolymer may occur. In addition, the polymerization yield is low, with several percent to several tens of percent of unreacted monomer remaining.
  • catalyst deactivation is generally performed in a large amount of high-temperature aqueous solution containing a basic compound such as triethylamine, during which the unreacted monomer dissolves in the treatment liquid.
  • a basic compound such as triethylamine
  • the polymerization product after deactivation in the manner described above has thermally unstable terminals. Therefore, purification and stabilization treatment by hydrolyzing the unstable parts of the terminals using an aqueous triethylamine solution or the like is necessary, which increases the number of steps and leads to increased costs.
  • the above problems can be solved by producing a polyacetal copolymer using a heteropolyacid or its acid salt as a polymerization catalyst, and a certain degree of success has been achieved.
  • the resulting polyacetal copolymer has other problems, such as reduced flowability during molding and poor surface properties of the molded product, and there is still room for improvement.
  • the present invention has been made in consideration of the above-mentioned problems of the conventional art, and its object is to provide a method for producing a polyacetal copolymer that has excellent flowability during molding and excellent surface properties of the molded product, even when the polyacetal copolymer is produced using a heteropolyacid as a polymerization catalyst.
  • the present inventors have found that the above problems can be solved by dissolving a heteropolyacid having a predetermined structure in a solvent having active hydrogen and using the resulting solution, and have thus completed the present invention.
  • One aspect of the present invention that solves the above problems is as follows.
  • (1) comprising a step of copolymerizing trioxane as a main monomer (a) and a compound copolymerizable with said trioxane as a comonomer (b),
  • a copolymerization reaction is carried out using a heteropolyacid represented by the following general formula (1) as a polymerization catalyst (c) in the form of a solution in a solvent having active hydrogen
  • a method for producing a polyacetal copolymer comprising adding, as a basic compound (d), a carbonate, bicarbonate or carboxylate of an alkali metal element or a hydrate thereof, a carbonate, bicarbonate or carboxylate of a Group 2 element (excluding Be) or a hydrate thereof, or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution to a crude polyacetal copolymer obtained by a copolymerization reaction, and melt-kneading the mixture.
  • M1 represents a central element selected from P, Si, B, and Ge.
  • M2 represents one or more coordination elements selected from W, Mo, and V.
  • x represents an integer of 1 or more and 10 or less
  • y represents an integer of 6 or more and 40 or less
  • z represents an integer of 10 or more and 100 or less
  • m represents an integer of 1 or more
  • n represents an integer of 0 or more and 50 or less.
  • the heteropolyacid is at least one selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, and silicomolybdotungstovanadic acid.
  • the present invention provides a method for producing a polyacetal copolymer that is excellent in fluidity during molding and surface properties of the molded product, even when a heteropolyacid is used as a polymerization catalyst to produce the polyacetal copolymer.
  • the method for producing a polyacetal copolymer according to the present embodiment includes a step of copolymerizing trioxane as the main monomer (a) and a compound copolymerizable with trioxane as the comonomer (b).
  • a heteropolyacid represented by the following general formula (1) is used as a polymerization catalyst (c) in the form of a solution in a solvent having active hydrogen to carry out a copolymerization reaction.
  • a basic compound such as a carbonate, hydrogencarbonate, or carboxylate of an alkali metal element or a hydrate thereof, a carbonate, hydrogencarbonate, or carboxylate of a Group 2 element (excluding Be; the same applies below), or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution, is added to the crude polyacetal copolymer obtained by the copolymerization reaction, and melt-kneaded.
  • M1 represents a central element selected from P, Si, B, and Ge.
  • M2 represents one or more coordination elements selected from W, Mo, and V.
  • x represents an integer of 1 or more and 10 or less
  • y represents an integer of 6 or more and 40 or less
  • z represents an integer of 10 or more and 100 or less
  • m represents an integer of 1 or more
  • n represents an integer of 0 or more and 50 or less.
  • the heteropolyacid represented by the general formula (1) is used as the polymerization catalyst (c) in the form of a solution dissolved in a solvent having active hydrogen to carry out the copolymerization reaction. That is, in this embodiment, the heteropolyacid represented by the general formula (1) is not used as is as the polymerization catalyst (c), but is used in the form of a solution dissolved in a solvent having active hydrogen. In this way, the polymerization reaction is stabilized, and the resulting copolymer has excellent fluidity during molding and excellent surface properties when molded into a molded product. The principle behind this is unclear, but is clear from experimental facts.
  • Trioxane the main monomer (a) is a cyclic trimer of formaldehyde, and is generally obtained by reacting an aqueous solution of formaldehyde in the presence of an acid catalyst, and is purified by methods such as distillation before use. It is preferable to use trioxane for polymerization in which impurities such as water and methanol have been reduced as much as possible.
  • comonomer (b) a compound that can be copolymerized with trioxane is used.
  • the comonomer (b) include cyclic ethers and/or cyclic formals having at least one carbon-carbon bond.
  • Representative examples of the compound used as the comonomer (b) include 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin, and the like.
  • At least one selected from the group consisting of 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, and ethylene oxide is preferred.
  • a known modifier comonomer such as a branching agent may be added as a third comonomer component, provided that the performance of the resulting polyacetal copolymer is not significantly deteriorated.
  • the amount of the compound selected from cyclic ethers and/or cyclic formals used as comonomer (b) is preferably 0.1 to 20 mol %, more preferably 0.2 to 10 mol %, of the total monomers (total amount of main monomer (a) and comonomer (b)). If the amount of comonomer (b) is less than 0.1 mol %, the amount of unstable terminals in the polyacetal copolymer produced by polymerization may increase, resulting in poor stability. If the amount of comonomer (b) exceeds 20 mol %, the resulting copolymer may become soft and the melting point may decrease.
  • a heteropolyacid represented by the following general formula (1) is used as the polymerization catalyst (c) in the form of a solution in a solvent having active hydrogen (hereinafter also referred to as a "polymerization catalyst solution").
  • M1 represents a central element selected from P, Si, B, and Ge.
  • M2 represents one or more coordination elements selected from W, Mo, and V.
  • x represents an integer of 1 or more and 10 or less
  • y represents an integer of 6 or more and 40 or less
  • z represents an integer of 10 or more and 100 or less
  • m represents an integer of 1 or more
  • n represents an integer of 0 or more and 50 or less.
  • y represents the number of M2 .
  • M2 is a single element
  • y represents the number of M2.
  • y represents the total number of the multiple elements.
  • M1 represents a central element selected from P, Si, B and Ge, with P or Si being preferred.
  • the heteropolyacid represented by general formula (1) serving as the polymerization catalyst (c) is preferably at least one selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, and silicomolybdotungstovanadic acid.
  • an acid salt having a structure in which part or all of Hm of the heteropolyacid is replaced by various metals may be used in combination as the polymerization catalyst (c).
  • Solvents with active hydrogen include water, alcohols with 1 to 5 carbon atoms, formic acid, etc.
  • alcohols with 1 to 5 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. Of these, water is preferred.
  • the concentration of the polymerization catalyst (c) in the polymerization catalyst solution is preferably 1.0 to 50.0 g/L, and more preferably 5.0 to 30.0 g/L.
  • the amount of polymerization catalyst (c) used can be 1.0 to 20.0 ppm by mass, and preferably 1.5 to 10.0 ppm by mass.
  • the main monomer (a), the comonomer (b), and the polymerization catalyst solution are put into a polymerization reactor to carry out the copolymerization reaction.
  • the main monomer (a), the comonomer (b), and the polymerization catalyst solution the main monomer (a) and the comonomer (b) are mixed together, and then the polymerization catalyst solution is added, or the main monomer (a) or the comonomer (b) is mixed with the polymerization catalyst solution, and then mixed with the comonomer (b) or the main monomer (a).
  • the polymerization reaction is preferably carried out by bulk polymerization using the main monomer (a) as a melt, and is usually started at 65°C or higher and 114°C or lower.
  • the polyacetal copolymer is insoluble in the main monomer (a) and will precipitate, but high-speed, powerful stirring is performed to prevent the reaction product from becoming lumpy, and the reaction product is pulverized.
  • To obtain a sustained reaction it is necessary to keep the temperature at 65°C or higher, but it is preferable to keep the temperature at 130°C or lower to prevent depolymerization reaction. More preferably, it is 70 to 125°C.
  • the polymerization time depends on the catalyst concentration, comonomer concentration, and reaction temperature, and cannot be limited, but a polymerization time of 0.5 to 10 minutes is generally selected.
  • a crude polyacetal copolymer By carrying out the copolymerization reaction as described above, a crude polyacetal copolymer can be obtained in a high yield.
  • This crude polyacetal copolymer contains almost no unreacted monomers, and therefore does not require a removal step of washing with hot water.
  • a basic compound (d) is added to the crude polyacetal copolymer and melt-kneaded.
  • the basic compound (d) functions as a basic deactivator for the polymerization catalyst (c), and the compound represented by the general formula (1) as the polymerization catalyst (c) can be deactivated by the basic compound (d).
  • the polymerization catalyst (c) can be deactivated without immersing the powder obtained by pulverizing the crude polyacetal copolymer in an aqueous solution of the deactivator and treating it for a long time in a solid-liquid heterogeneous state, as in the conventional method. Therefore, the process from immersing in an aqueous solution of the deactivator to drying can be omitted. Furthermore, since the generation of thermally unstable terminals generated by immersing in an aqueous solution of the deactivator for a long time can be suppressed, no stabilization treatment is required.
  • thermally unstable terminals examples include -CH 2 CH 2 O-(CH 2 O) n -CH 2 OH and -CH 2 CH 2 O-(CH 2 O) n -CH 2 O-CHO.
  • n represents zero or any positive integer.
  • the basic compound (d) is an alkali metal carbonate, bicarbonate or carboxylate or a hydrate thereof, or a Group 2 element carbonate, bicarbonate or carboxylate or a hydrate thereof, or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution.
  • alkali metal carbonate, bicarbonate or carboxylate or a hydrate thereof, or the Group 2 element carbonate, bicarbonate or carboxylate or a hydrate thereof include sodium carbonate, sodium bicarbonate, potassium carbonate, calcium carbonate, calcium bicarbonate, sodium formate, sodium acetate, disodium succinate, sodium laurate, sodium palmitate, sodium stearate, calcium stearate, sodium hydroxide, potassium hydroxide, etc.
  • nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution include amine compounds such as triethylamine, choline hydroxide, trimethylamine, and ethanolamine.
  • an alkali metal carbonate, bicarbonate or carboxylate or a hydrate thereof is preferable.
  • the pH of a nitrogen-containing organic compound with a pH of 10 or more in a 10 g/L aqueous solution is the pH at 25°C.
  • the type and method of addition of the basic compound (d) are not particularly limited, but a basic compound (d) that can be used to inactivate the polymerization catalyst and remove the unstable terminals of the polyacetal copolymer by adding the basic compound (d) directly to the polymerization reaction product, i.e., the polyacetal copolymer, without washing it, and melt-kneading the polyacetal copolymer, is used.
  • the polymerization catalyst can be inactivated by melt-kneading in an extruder, but decomposition and removal of the unstable terminals is insufficient.
  • the amount of formaldehyde generated in the final composition is particularly low, which is more preferable.
  • the basic compound (d) may be one type, or two or more types may be used in combination, and may be in the form of a hydrate, mixture, double salt, etc.
  • the amount of polymerization catalyst (c) used is small, so the amount of basic compound (d) used, which is a deactivator for the polymerization catalyst (c), can also be small. Specifically, it can be 1 to 100 ppm relative to the polymerization product.
  • a molecular weight regulator may be used as necessary.
  • a linear formal compound can be used as the molecular weight regulator.
  • linear formal compounds include methylal, ethylal, dibutoxymethane, bis(methoxymethyl) ether, bis(ethoxymethyl) ether, and bis(butoxymethyl) ether.
  • an antioxidant may be added in the polymerization step as necessary.
  • Examples 1 to 11, Comparative Examples 1 to 2 A continuous twin-screw polymerization machine was used as the polymerization reaction apparatus. This polymerization machine was provided with a jacket for passing a heating or cooling medium on the outside, and two rotating shafts with many paddles for stirring, propulsion and crushing were provided in the longitudinal direction inside. Then, while rotating each of the two rotating shafts of the polymerization machine at 250 rpm, the main monomer (trioxane) and the comonomers shown in Table 1 were added in the ratios shown in Table 1.
  • methylal was added as a molecular weight modifier as necessary so that the melt flow rate of the obtained crude polymer was 9.0 g/10 min, and the polymerization catalyst was continuously added and fed in a solution (aqueous solution: 20.0 g/L, methyl formate: 2.0 g/L, others: 15.0 g/L) in which the polymerization catalyst shown in Table 1 was dissolved in the solvent shown in Table 1 so that the amount of catalyst added was 5 ppm in the methyl formate solution and 10 ppm in the others with respect to the total monomer, and bulk polymerization was performed, and a powdery crude polyacetal copolymer was obtained which was crushed and discharged from the polymerization machine.
  • a solution aqueous solution: 20.0 g/L, methyl formate: 2.0 g/L, others: 15.0 g/L
  • the polymerization catalyst shown in Table 1 was dissolved in the solvent shown in Table 1 so that the amount of catalyst added was 5 ppm in the methyl formate solution and 10
  • Comparative Example 2 a crude polyacetal copolymer was obtained by the same operation as in Example 1, and then 0.3 mass % of Irganox 1010 (manufactured by BASF Japan Ltd.) as an antioxidant and 0.1 mass % of melamine as a deactivating agent were added to the crude polyacetal copolymer obtained and melt-kneaded (cylinder temperature: 200° C.) to deactivate the polymerization catalyst, thereby obtaining pellets of the polyacetal copolymer.
  • Irganox 1010 manufactured by BASF Japan Ltd.
  • melamine a deactivating agent
  • catalysts 1 and 2 are as follows.
  • Catalyst 1 phosphotungstic acid (H 3 PW 12 O 40 )
  • Catalyst 2 Phosphomolybdic acid (H 3 PMo 12 O 40 )
  • the flow length is 440 mm or more and less than 450 mm.
  • 3 The flow length is 430 mm or more and less than 440 mm.
  • 2 The flow length is 420 mm or more and less than 430 mm.
  • 1 The flow length is less than 420 mm.
  • Thermal stability (amount of formaldehyde generated from the melt) 5 g of the obtained polyacetal copolymer pellets were weighed and filled into a cylinder kept at 200°C. After melting for 5 minutes, the melt was extruded into a sealed container. Nitrogen gas was passed through the sealed container, and formaldehyde contained in the nitrogen gas that came out was collected in water. The formaldehyde concentration in the water was measured according to JIS K0102 29.1 (2013) to determine the mass of formaldehyde from the melt. This mass was divided by the mass of the polyacetal copolymer used to obtain the amount of formaldehyde generated (unit: ppm). It is practically preferable that the amount of formaldehyde generated by this method is 70 ppm or less.

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Abstract

The present invention is a method for producing a polyacetal copolymer that includes a step that copolymerizes trioxane as the main monomer (a) with a compound that can be copolymerized with trioxane as the comonomer (b), in which step a copolymerization reaction is carried out using a heteropoly acid having a predetermined structure as a polymerization catalyst (c) as a solution of a solvent having an active hydrogen, and a basic compound (d) is added to and melt kneaded with the crude polyacetal copolymer obtained.

Description

ポリアセタール共重合体の製造方法Method for producing polyacetal copolymer
　本発明は、ポリアセタール共重合体の製造方法に関する。 The present invention relates to a method for producing a polyacetal copolymer.
　ポリアセタール共重合体は、機械的性質、耐薬品性、摺動性等のバランスに優れ、かつ、その加工が容易であることにより、エンジニアリングプラスチックとして、電気・電子部品、自動車部品その他の各種機械部品を中心として広く利用されている。 Polyacetal copolymers have an excellent balance of mechanical properties, chemical resistance, and sliding properties, and are easy to process, making them widely used as engineering plastics, primarily in electrical and electronic components, automotive parts, and various other machine parts.
　ポリアセタール共重合体は、トリオキサンを主モノマーとし、該トリオキサンと共重合し得る化合物をコモノマーとして共重合する共重合体（コポリマー）である。そして、ポリアセタール共重合体（コポリマー）の製造方法として、トリオキサンを主モノマーとし、少なくとも一つの炭素－炭素結合を有する環状エーテル及び／又は環状ホルマールをコモノマーとするカチオン共重合が知られている。共重合に用いるカチオン活性触媒としては、中でも三フッ化ホウ素、又は三フッ化ホウ素と有機化合物、例えばエーテル類との配位化合物は、トリオキサンを主モノマーとする重合触媒として最も一般的であり、工業的にも広く用いられている。 Polyacetal copolymers are copolymers in which trioxane is the main monomer and a compound that can be copolymerized with trioxane is used as a comonomer. A known method for producing polyacetal copolymers is cationic copolymerization in which trioxane is the main monomer and a cyclic ether and/or cyclic formal having at least one carbon-carbon bond is used as a comonomer. As for cationic active catalysts used in copolymerization, boron trifluoride or a coordination compound of boron trifluoride and an organic compound, such as an ether, is the most common polymerization catalyst for trioxane as the main monomer and is widely used industrially.
　しかし、三フッ化ホウ素系化合物等の一般に使用される重合触媒では、重合に比較的多量（例えば全モノマーに対し４０ｐｐｍ又はそれ以上）の触媒を必要とする。そのため、重合後の触媒失活処理を十分に行い難く、また、失活化させたとしても触媒に由来する物質が共重合体中に残存し、共重合体の分解が促進される等の問題が生じる場合がある。また、重合収率は低く未反応モノマーが数％から数十％残っている。そのため触媒の失活はトリエチルアミン等の塩基性化合物を含む多量の高温水溶液中で処理するのが一般的であり、その際に未反応のモノマーは処理液中に溶出する。触媒失活後に共重合体を未反応モノマーが溶解した処理液と分離洗浄した後に乾燥する工程等、煩雑な工程を必要とするものであり、経済的にも課題を含むものであった。 However, commonly used polymerization catalysts such as boron trifluoride compounds require a relatively large amount of catalyst (for example, 40 ppm or more relative to the total monomers) for polymerization. This makes it difficult to perform sufficient catalyst deactivation treatment after polymerization, and even if the catalyst is deactivated, problems such as substances derived from the catalyst remaining in the copolymer and promoting decomposition of the copolymer may occur. In addition, the polymerization yield is low, with several percent to several tens of percent of unreacted monomer remaining. For this reason, catalyst deactivation is generally performed in a large amount of high-temperature aqueous solution containing a basic compound such as triethylamine, during which the unreacted monomer dissolves in the treatment liquid. This requires complicated processes such as separating the copolymer from the treatment liquid in which the unreacted monomer is dissolved, washing it, and then drying it after catalyst deactivation, which is economically problematic.
　一方、上記のようにして失活した後の重合生成物には、熱的に不安定な末端が存在する。そのため、トリエチルアミン水溶液などを用いた末端の不安定部分を加水分解することによる精製安定化処理が必要であり、その分、工数が増え、コスト増加の原因にもなる。 On the other hand, the polymerization product after deactivation in the manner described above has thermally unstable terminals. Therefore, purification and stabilization treatment by hydrolyzing the unstable parts of the terminals using an aqueous triethylamine solution or the like is necessary, which increases the number of steps and leads to increased costs.
　そこで、上記のような問題を解決するため、重合触媒としてヘテロポリ酸又はその酸性塩を使用することが提案されている（特許文献１参照）。 In order to solve the above problems, it has been proposed to use a heteropolyacid or its acid salt as a polymerization catalyst (see Patent Document 1).
特開平１－１７０６１０号公報Japanese Patent Application Laid-Open No. 1-170610
　特許文献１のように、重合触媒としてヘテロポリ酸又はその酸性塩を使用してポリアセタール共重合体を製造することにより、上記諸問題を解決することができ、一定の成果が得られた。しかし、得られたポリアセタール共重合体は成形時の流動性が低下することや、その成形品の表面性が悪化するという別の問題があり、改善の余地が残されていた。 As described in Patent Document 1, the above problems can be solved by producing a polyacetal copolymer using a heteropolyacid or its acid salt as a polymerization catalyst, and a certain degree of success has been achieved. However, the resulting polyacetal copolymer has other problems, such as reduced flowability during molding and poor surface properties of the molded product, and there is still room for improvement.
　本発明は、上記従来の問題点に鑑みなされたものであり、その課題は、ヘテロポリ酸を重合触媒として使用してポリアセタール共重合体を製造する場合であっても、成形時の流動性及び成形品の表面性に優れる、ポリアセタール共重合体の製造方法を提供することにある。 The present invention has been made in consideration of the above-mentioned problems of the conventional art, and its object is to provide a method for producing a polyacetal copolymer that has excellent flowability during molding and excellent surface properties of the molded product, even when the polyacetal copolymer is produced using a heteropolyacid as a polymerization catalyst.
　本発明者は、所定の構造を有するヘテロポリ酸を、活性水素を持つ溶媒に溶解し、溶液として使用することで前記問題点を解決することができることを見出し、本発明を完成するに至った。
　前記課題を解決する本発明の一態様は以下の通りである。 The present inventors have found that the above problems can be solved by dissolving a heteropolyacid having a predetermined structure in a solvent having active hydrogen and using the resulting solution, and have thus completed the present invention.
One aspect of the present invention that solves the above problems is as follows.
（１）主モノマー（ａ）としてトリオキサンと、コモノマー（ｂ）として前記トリオキサンと共重合し得る化合物とを共重合する工程を含み、
　前記工程において、重合触媒（ｃ）として、下記一般式（１）で表されるヘテロポリ酸を、活性水素を持つ溶媒の溶液として使用して共重合反応を行い、
　共重合反応によって得られる粗ポリアセタール共重合体に塩基性化合物（ｄ）として、アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は第２族元素（Ｂｅを除く。）の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は１０ｇ／Ｌ水溶液のｐＨが１０以上の窒素含有有機化合物を添加して溶融混練を行う、ポリアセタール共重合体の製造方法。
　Ｈｍ［Ｍ１ ｘ・Ｍ２ ｙＯＺ］・ｎＨ２Ｏ　　・・・一般式（１）
〔一般式（１）中、Ｍ１はＰ、Ｓｉ、Ｂ及びＧｅより選択される元素からなる中心元素を表す。Ｍ２はＷ、Ｍｏ及びＶより選択される１種以上の配位元素を表す。ｘは１以上１０以下の整数を示し、ｙは６以上４０以下の整数を表し、ｚは１０以上１００以下の整数を表し、ｍは１以上の整数を表し、ｎは０以上５０以下の整数を表す。〕 (1) comprising a step of copolymerizing trioxane as a main monomer (a) and a compound copolymerizable with said trioxane as a comonomer (b),
In the above step, a copolymerization reaction is carried out using a heteropolyacid represented by the following general formula (1) as a polymerization catalyst (c) in the form of a solution in a solvent having active hydrogen,
A method for producing a polyacetal copolymer, comprising adding, as a basic compound (d), a carbonate, bicarbonate or carboxylate of an alkali metal element or a hydrate thereof, a carbonate, bicarbonate or carboxylate of a Group 2 element (excluding Be) or a hydrate thereof, or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution to a crude polyacetal copolymer obtained by a copolymerization reaction, and melt-kneading the mixture.
Hm [ M1x.M2yOz ] .nH2O General formula ( 1 )
[In the general formula (1), M1 represents a central element selected from P, Si, B, and Ge. M2 represents one or more coordination elements selected from W, Mo, and V. x represents an integer of 1 or more and 10 or less, y represents an integer of 6 or more and 40 or less, z represents an integer of 10 or more and 100 or less, m represents an integer of 1 or more, and n represents an integer of 0 or more and 50 or less.]
（２）前記アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は第２族元素（Ｂｅを除く。）の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物が、アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物である、前記（１）に記載のポリアセタール共重合体の製造方法。 (2) The method for producing a polyacetal copolymer according to (1) above, wherein the carbonate, hydrogencarbonate or carboxylate of an alkali metal element or a hydrate thereof, or the carbonate, hydrogencarbonate or carboxylate of a Group 2 element (excluding Be) or a hydrate thereof is a carbonate, hydrogencarbonate or carboxylate of an alkali metal element or a hydrate thereof.
（３）前記コモノマー（ｂ）が、１，３－ジオキソラン、ジエチレングリコールホルマール、１，４－ブタンジオールホルマール、１，３－ジオキサン、及びエチレンオキシドからなる群より選択される少なくとも１種である、前記（１）又は（２）に記載のポリアセタール共重合体の製造方法。 (3) The method for producing a polyacetal copolymer according to (1) or (2) above, wherein the comonomer (b) is at least one selected from the group consisting of 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, and ethylene oxide.
（４）前記ヘテロポリ酸が、リンモリブデン酸、リンタングステン酸、リンモリブドタングステン酸、リンモリブドバナジン酸、リンモリブドタングストバナジン酸、リンタングストバナジン酸、ケイタングステン酸、ケイモリブデン酸、ケイモリブドタングステン酸、及びケイモリブドタングストバナジン酸からなる群より選択される少なくとも１種である、前記（１）～（３）のいずれかに記載のポリアセタール共重合体の製造方法。 (4) The method for producing a polyacetal copolymer according to any one of (1) to (3), wherein the heteropolyacid is at least one selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, and silicomolybdotungstovanadic acid.
　本発明によれば、ヘテロポリ酸を重合触媒として使用してポリアセタール共重合体を製造する場合であっても、成形時の流動性及び成形品の表面性に優れる、ポリアセタール共重合体の製造方法を提供することができる。 The present invention provides a method for producing a polyacetal copolymer that is excellent in fluidity during molding and surface properties of the molded product, even when a heteropolyacid is used as a polymerization catalyst to produce the polyacetal copolymer.
　本実施形態のポリアセタール共重合体の製造方法は、主モノマー（ａ）としてトリオキサンと、コモノマー（ｂ）としてトリオキサンと共重合し得る化合物とを共重合する工程を含む。そして、前記工程において、重合触媒（ｃ）として、下記一般式（１）で表されるヘテロポリ酸を、活性水素を持つ溶媒の溶液として使用して共重合反応を行う。そして、共重合反応によって得られる粗ポリアセタール共重合体に塩基性化合物として、アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は第２族元素（Ｂｅを除く。以下においても同じとする。）の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は１０ｇ／Ｌ水溶液のｐＨが１０以上の窒素含有有機化合物を添加して溶融混練を行う。
　Ｈｍ［Ｍ１ ｘ・Ｍ２ ｙＯＺ］・ｎＨ２Ｏ　　・・・一般式（１）
〔一般式（１）中、Ｍ１はＰ、Ｓｉ、Ｂ及びＧｅより選択される元素からなる中心元素を表す。Ｍ２はＷ、Ｍｏ及びＶより選択される１種以上の配位元素を表す。ｘは１以上１０以下の整数を示し、ｙは６以上４０以下の整数を表し、ｚは１０以上１００以下の整数を表し、ｍは１以上の整数を表し、ｎは０以上５０以下の整数を表す。〕 The method for producing a polyacetal copolymer according to the present embodiment includes a step of copolymerizing trioxane as the main monomer (a) and a compound copolymerizable with trioxane as the comonomer (b). In the step, a heteropolyacid represented by the following general formula (1) is used as a polymerization catalyst (c) in the form of a solution in a solvent having active hydrogen to carry out a copolymerization reaction. A basic compound, such as a carbonate, hydrogencarbonate, or carboxylate of an alkali metal element or a hydrate thereof, a carbonate, hydrogencarbonate, or carboxylate of a Group 2 element (excluding Be; the same applies below), or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution, is added to the crude polyacetal copolymer obtained by the copolymerization reaction, and melt-kneaded.
Hm [ M1x.M2yOz ] .nH2O General formula ( 1 )
[In the general formula (1), M1 represents a central element selected from P, Si, B, and Ge. M2 represents one or more coordination elements selected from W, Mo, and V. x represents an integer of 1 or more and 10 or less, y represents an integer of 6 or more and 40 or less, z represents an integer of 10 or more and 100 or less, m represents an integer of 1 or more, and n represents an integer of 0 or more and 50 or less.]
　本実施形態の製造方法においては、主モノマー（ａ）としてトリオキサンと、コモノマー（ｂ）としてトリオキサンと共重合し得る化合物とを共重合する工程において、重合触媒（ｃ）として前記一般式（１）で表されるヘテロポリ酸を、活性水素を持つ溶媒に溶解した溶液として使用して共重合反応を行う。すなわち、本実施形態においては、重合触媒（ｃ）として、前記一般式（１）で表されるヘテロポリ酸をそのままの状態で使用するのではなく、活性水素を持つ溶媒に溶解して溶液の状態で使用する。そのようにすると、重合反応が安定化し、得られる共重合体は成形時の流動性及び成形品としたときの表面性に優れる。そのようになる原理は不明であるが、実験事実から明らかである。 In the manufacturing method of this embodiment, in the step of copolymerizing trioxane as the main monomer (a) and a compound copolymerizable with trioxane as the comonomer (b), the heteropolyacid represented by the general formula (1) is used as the polymerization catalyst (c) in the form of a solution dissolved in a solvent having active hydrogen to carry out the copolymerization reaction. That is, in this embodiment, the heteropolyacid represented by the general formula (1) is not used as is as the polymerization catalyst (c), but is used in the form of a solution dissolved in a solvent having active hydrogen. In this way, the polymerization reaction is stabilized, and the resulting copolymer has excellent fluidity during molding and excellent surface properties when molded into a molded product. The principle behind this is unclear, but is clear from experimental facts.
　主モノマー（ａ）としてのトリオキサンは、ホルムアルデヒドの環状三量体であり、一般的には酸性触媒の存在下でホルムアルデヒド水溶液を反応させることによって得られ、これを蒸留等の方法で精製して用いられる。重合に用いるトリオキサンは、水、メタノールなどの不純物を極力低減させたものが好ましい。 Trioxane, the main monomer (a), is a cyclic trimer of formaldehyde, and is generally obtained by reacting an aqueous solution of formaldehyde in the presence of an acid catalyst, and is purified by methods such as distillation before use. It is preferable to use trioxane for polymerization in which impurities such as water and methanol have been reduced as much as possible.
　コモノマー（ｂ）は、トリオキサンと共重合し得る化合物が使用される。コモノマー（ｂ）としては、例えば、少なくとも１つの炭素－炭素結合を有する環状エーテル及び／又は環状ホルマールが挙げられる。コモノマー（ｂ）として使用する化合物の代表的な例としては、例えば、１，３－ジオキソラン、ジエチレングリコールホルマール、１，４－ブタンジオールホルマール、１，３－ジオキサン、エチレンオキシド、プロピレンオキシド、エピクロルヒドリン等が挙げられる。中でも、重合の安定性から考慮して、１，３－ジオキソラン、ジエチレングリコールホルマール、１，４－ブタンジオールホルマール、１，３－ジオキサン、及びエチレンオキシドからなる群より選択される少なくとも１種が好ましい。
　更に、得られるポリアセタール共重合体の性能を大幅に低下させないような範囲ならば、主モノマー（ａ）及びコモノマー（ｂ）に加えて、第三のコモノマー成分として、分岐剤などの公知の変性剤コモノマーを併用添加しても差し支えない。 As the comonomer (b), a compound that can be copolymerized with trioxane is used. Examples of the comonomer (b) include cyclic ethers and/or cyclic formals having at least one carbon-carbon bond. Representative examples of the compound used as the comonomer (b) include 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin, and the like. Among them, in consideration of the stability of the polymerization, at least one selected from the group consisting of 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, and ethylene oxide is preferred.
Furthermore, in addition to the main monomer (a) and the comonomer (b), a known modifier comonomer such as a branching agent may be added as a third comonomer component, provided that the performance of the resulting polyacetal copolymer is not significantly deteriorated.
　本実施形態において、コモノマー（ｂ）として用いる、環状エーテル及び／又は環状ホルマールから選ばれる化合物の量は、全モノマー（主モノマー（ａ）とコモノマー（ｂ）の合計量）中の割合として０．１～２０モル％であることが好ましく、０．２～１０モル％であることがより好ましい。コモノマー（ｂ）の量が０．１モル％未満であると、重合によって生成するポリアセタール共重合体の不安定末端部が増加して安定性が悪くなることがある。コモノマー（ｂ）の量が２０モル％を超えると、生成共重合体が軟質となり融点の低下を生じることがある。 In this embodiment, the amount of the compound selected from cyclic ethers and/or cyclic formals used as comonomer (b) is preferably 0.1 to 20 mol %, more preferably 0.2 to 10 mol %, of the total monomers (total amount of main monomer (a) and comonomer (b)). If the amount of comonomer (b) is less than 0.1 mol %, the amount of unstable terminals in the polyacetal copolymer produced by polymerization may increase, resulting in poor stability. If the amount of comonomer (b) exceeds 20 mol %, the resulting copolymer may become soft and the melting point may decrease.
　本実施形態の製造方法においては、重合触媒（ｃ）として下記一般式（１）で表されるヘテロポリ酸を、活性水素を持つ溶媒の溶液（以下、「重合触媒溶液」とも呼ぶ。）として使用する。
　　Ｈｍ［Ｍ１ ｘ・Ｍ２ ｙＯＺ］・ｎＨ２Ｏ　　・・・一般式（１）
〔一般式（１）中、Ｍ１はＰ、Ｓｉ、Ｂ及びＧｅより選択される元素からなる中心元素を表す。Ｍ２はＷ、Ｍｏ及びＶより選択される１種以上の配位元素を表す。ｘは１以上１０以下の整数を示し、ｙは６以上４０以下の整数を表し、ｚは１０以上１００以下の整数を表し、ｍは１以上の整数を表し、ｎは０以上５０以下の整数を表す。〕
　なお、ｙは、Ｍ２の個数を表すが、Ｍ２が単一の場合はその個数を表し、Ｍ２が複数種からなる場合はそれら複数種の元素の合計を表す。 In the production method of this embodiment, a heteropolyacid represented by the following general formula (1) is used as the polymerization catalyst (c) in the form of a solution in a solvent having active hydrogen (hereinafter also referred to as a "polymerization catalyst solution").
Hm [ M1x.M2yOz ] .nH2O General formula ( 1 )
[In the general formula (1), M1 represents a central element selected from P, Si, B, and Ge. M2 represents one or more coordination elements selected from W, Mo, and V. x represents an integer of 1 or more and 10 or less, y represents an integer of 6 or more and 40 or less, z represents an integer of 10 or more and 100 or less, m represents an integer of 1 or more, and n represents an integer of 0 or more and 50 or less.]
In addition, y represents the number of M2 . When M2 is a single element, y represents the number of M2. When M2 is composed of multiple elements, y represents the total number of the multiple elements.
　Ｍ１はＰ、Ｓｉ、Ｂ及びＧｅより選択される元素からなる中心元素を表すが、Ｐ又はＳｉが好ましい。 M1 represents a central element selected from P, Si, B and Ge, with P or Si being preferred.
　重合触媒（ｃ）たる一般式（１）で表されるヘテロポリ酸としては、リンモリブデン酸、リンタングステン酸、リンモリブドタングステン酸、リンモリブドバナジン酸、リンモリブドタングストバナジン酸、リンタングストバナジン酸、ケイタングステン酸、ケイモリブデン酸、ケイモリブドタングステン酸、及びケイモリブドタングストバナジン酸からなる群より選択される少なくとも１種であることが好ましい。 The heteropolyacid represented by general formula (1) serving as the polymerization catalyst (c) is preferably at least one selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, and silicomolybdotungstovanadic acid.
　本実施形態においては、重合触媒（ｃ）として、一般式（１）で表されるヘテロポリ酸に加え、当該ヘテロポリ酸のＨｍの一部又は全部が各種金属に置き換わった構造の酸性塩を併用してもよい。 In this embodiment, in addition to the heteropolyacid represented by the general formula (1), an acid salt having a structure in which part or all of Hm of the heteropolyacid is replaced by various metals may be used in combination as the polymerization catalyst (c).
　活性水素を持つ溶媒としては、水、炭素原子数１～５のアルコール、ギ酸等が挙げられる。炭素原子数１～５のアルコールとしては、メタノール、エタノール、ｎ－プロパノール、イソプロパノール、ｎ－ブタノール、等が挙げられる。中でも、水が好ましい。 Solvents with active hydrogen include water, alcohols with 1 to 5 carbon atoms, formic acid, etc. Examples of alcohols with 1 to 5 carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc. Of these, water is preferred.
　重合触媒溶液中の重合触媒（ｃ）の濃度としては、１．０～５０．０ｇ／Ｌとすることが好ましく、５．０～３０．０ｇ／Ｌとすることがより好ましい。 The concentration of the polymerization catalyst (c) in the polymerization catalyst solution is preferably 1.0 to 50.0 g/L, and more preferably 5.0 to 30.0 g/L.
　本実施形態の製造方法においては、重合触媒（ｃ）の使用量を少なくしても、高い収率で共重合体が得られる。具体的には、主モノマー（ａ）及びコモノマー（ｂ）の合計量に対する重合触媒（ｃ）の使用量は１．０～２０．０質量ｐｐｍとすることができ、１．５～１０．０質量ｐｐｍとすることが好ましい。そして、このような少量の重合触媒（ｃ）でも共重合が可能なことは、重合触媒による重合体の主鎖分解、解重合等の好ましくない反応を僅少に留め、不安定なホルメート末端基（－Ｏ－ＣＨ＝Ｏ）、ヘミアセタール末端基（－Ｏ－ＣＨ２－ＯＨ）等の生成を抑制するのに効果的であり、また、経済的にも有利である。 In the production method of this embodiment, even if the amount of polymerization catalyst (c) used is small, a copolymer can be obtained in high yield. Specifically, the amount of polymerization catalyst (c) used relative to the total amount of main monomer (a) and comonomer (b) can be 1.0 to 20.0 ppm by mass, and preferably 1.5 to 10.0 ppm by mass. The fact that copolymerization is possible even with such a small amount of polymerization catalyst (c) is effective in minimizing undesirable reactions such as main chain decomposition and depolymerization of the polymer caused by the polymerization catalyst, and in suppressing the generation of unstable formate end groups (-O-CH=O), hemiacetal end groups (-O-CH 2 -OH), and the like, and is also economically advantageous.
　本実施形態においては、主モノマー（ａ）と、コモノマー（ｂ）と、重合触媒溶液とを重合反応装置に投入して共重合反応を行う。この際、主モノマー（ａ）、コモノマー（ｂ）、及び重合触媒溶液のうち、主モノマー（ａ）とコモノマー（ｂ）とを混合した後に、重合触媒溶液を加えるか、あるいは主モノマー（ａ）又はコモノマー（ｂ）に重合触媒溶液を混合した後に、コモノマー（ｂ）又は主モノマー（ａ）と混合する。また、重合反応は主モノマー（ａ）を融液としたバルク重合で行うことが好ましく、通常、６５℃以上１１４℃以下で開始させる。ポリアセタール共重合体は主モノマー（ａ）に不溶であるので析出するが、岩塊状とならないように高速で強力な撹拌を行い、反応生成物の粉砕を行う。持続的な反応を得るためには６５℃以上に保つ必要があるが解重合反応が起こらないよう１３０℃以下に保つことが好ましい。より好ましくは７０～１２５℃である。 In this embodiment, the main monomer (a), the comonomer (b), and the polymerization catalyst solution are put into a polymerization reactor to carry out the copolymerization reaction. In this case, of the main monomer (a), the comonomer (b), and the polymerization catalyst solution, the main monomer (a) and the comonomer (b) are mixed together, and then the polymerization catalyst solution is added, or the main monomer (a) or the comonomer (b) is mixed with the polymerization catalyst solution, and then mixed with the comonomer (b) or the main monomer (a). The polymerization reaction is preferably carried out by bulk polymerization using the main monomer (a) as a melt, and is usually started at 65°C or higher and 114°C or lower. The polyacetal copolymer is insoluble in the main monomer (a) and will precipitate, but high-speed, powerful stirring is performed to prevent the reaction product from becoming lumpy, and the reaction product is pulverized. To obtain a sustained reaction, it is necessary to keep the temperature at 65°C or higher, but it is preferable to keep the temperature at 130°C or lower to prevent depolymerization reaction. More preferably, it is 70 to 125°C.
　重合時間は、触媒濃度、コモノマー濃度、反応温度に依存し、特に限定できないが、一般には０．５～１０分の重合時間が選ばれる。 The polymerization time depends on the catalyst concentration, comonomer concentration, and reaction temperature, and cannot be limited, but a polymerization time of 0.5 to 10 minutes is generally selected.
　以上のように共重合反応を行うことで、粗ポリアセタール共重合体が高い収率で得られる。この粗ポリアセタール共重合体は未反応モノマーがほとんど残存しておらず、熱水で洗浄を行う除去工程が不要となる。そして、本実施形態の製造方法においては、当該粗ポリアセタール共重合体に塩基性化合物（ｄ）を添加して溶融混練を行う。塩基性化合物（ｄ）は、重合触媒（ｃ）に対して塩基性失活剤としての機能を有し、塩基性化合物（ｄ）により、重合触媒（ｃ）たる前記一般式（１）で表される化合物を失活することができる。しかも、失活は均一な溶融樹脂中で行われるため、従来のように、粗ポリアセタール共重合体を粉砕した粉末を失活剤の水溶液に浸漬し、固液不均一な状態で長時間処理することなく、重合触媒（ｃ）を失活することができる。そのため、失活剤の水溶液に浸漬してから乾燥するまでの工程を省略することができる。さらに、失活剤の水溶液に長時間浸漬することで生成する、熱的に不安定な末端の生成を抑制することができるため、安定化処理を必要としない。熱的に不安定な末端としては、－ＣＨ２ＣＨ２Ｏ－（ＣＨ２Ｏ）ｎ－ＣＨ２ＯＨや－ＣＨ２ＣＨ２Ｏ－（ＣＨ２Ｏ）ｎ－ＣＨ２Ｏ－ＣＨＯが挙げられる。上記不安定な末端を示す基の中のｎはゼロ又は任意の正の整数を示す。さらには、従来は塩基性溶液に浸漬することで粗共重合体中の触媒を失活させていた際に水溶液中に抽出されていた未反応モノマーも回収が可能となり、モノマーの損失が抑制可能となる。 By carrying out the copolymerization reaction as described above, a crude polyacetal copolymer can be obtained in a high yield. This crude polyacetal copolymer contains almost no unreacted monomers, and therefore does not require a removal step of washing with hot water. In the manufacturing method of this embodiment, a basic compound (d) is added to the crude polyacetal copolymer and melt-kneaded. The basic compound (d) functions as a basic deactivator for the polymerization catalyst (c), and the compound represented by the general formula (1) as the polymerization catalyst (c) can be deactivated by the basic compound (d). In addition, since the deactivation is carried out in a uniform molten resin, the polymerization catalyst (c) can be deactivated without immersing the powder obtained by pulverizing the crude polyacetal copolymer in an aqueous solution of the deactivator and treating it for a long time in a solid-liquid heterogeneous state, as in the conventional method. Therefore, the process from immersing in an aqueous solution of the deactivator to drying can be omitted. Furthermore, since the generation of thermally unstable terminals generated by immersing in an aqueous solution of the deactivator for a long time can be suppressed, no stabilization treatment is required. Examples of thermally unstable terminals include -CH 2 CH 2 O-(CH 2 O) n -CH 2 OH and -CH 2 CH 2 O-(CH 2 O) n -CH 2 O-CHO. In the group indicating the above unstable terminal, n represents zero or any positive integer. Furthermore, it is possible to recover unreacted monomers that were extracted into an aqueous solution when the catalyst in the crude copolymer was deactivated by immersion in a basic solution in the past, and loss of monomers can be suppressed.
　本実施形態において、塩基性化合物（ｄ）としては、アルカリ金属の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は第２族元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は１０ｇ／Ｌ水溶液のｐＨが１０以上の窒素含有有機化合物を用いる。アルカリ金属の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は第２族元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物としては、炭酸ナトリウム、炭酸水素ナトリウム、炭酸カリウム、炭酸カルシウム、炭酸水素カルシウム、ギ酸ナトリウム、酢酸ナトリウム、コハク酸二ナトリウム、ラウリン酸ナトリウム、パルミチン酸ナトリウム、ステアリン酸ナトリウム、ステアリン酸カルシウム、水酸化ナトリウム、水酸化カリウム等が挙げられる。１０ｇ／Ｌ水溶液のｐＨが１０以上の窒素含有有機化合物としては、トリエチルアミン、水酸化コリン、トリメチルアミン、エタノールアミン等のアミン化合物等が挙げられる。中でも、アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物であることが好ましい。なお、１０ｇ／Ｌ水溶液のｐＨが１０以上の窒素含有有機化合物におけるｐＨとは２５℃におけるｐＨである。 In this embodiment, the basic compound (d) is an alkali metal carbonate, bicarbonate or carboxylate or a hydrate thereof, or a Group 2 element carbonate, bicarbonate or carboxylate or a hydrate thereof, or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution. Examples of the alkali metal carbonate, bicarbonate or carboxylate or a hydrate thereof, or the Group 2 element carbonate, bicarbonate or carboxylate or a hydrate thereof, include sodium carbonate, sodium bicarbonate, potassium carbonate, calcium carbonate, calcium bicarbonate, sodium formate, sodium acetate, disodium succinate, sodium laurate, sodium palmitate, sodium stearate, calcium stearate, sodium hydroxide, potassium hydroxide, etc. Examples of the nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution include amine compounds such as triethylamine, choline hydroxide, trimethylamine, and ethanolamine. Among these, an alkali metal carbonate, bicarbonate or carboxylate or a hydrate thereof is preferable. Note that the pH of a nitrogen-containing organic compound with a pH of 10 or more in a 10 g/L aqueous solution is the pH at 25°C.
　塩基性化合物（ｄ）の種類、添加方法は、特に限定されるものでないが、重合反応生成物、すなわち、ポリアセタール共重合体を洗浄することなく、ポリアセタール共重合体に対して塩基性化合物（ｄ）をそのまま添加し溶融混練することで、重合触媒の失活及びポリアセタール共重合体の不安定末端の除去に供することができるものを用いる。それらの塩基性化合物（ｄ）以外では、押出機での溶融混練で重合触媒の失活はできるが、不安定末端の分解除去は不十分である。 The type and method of addition of the basic compound (d) are not particularly limited, but a basic compound (d) that can be used to inactivate the polymerization catalyst and remove the unstable terminals of the polyacetal copolymer by adding the basic compound (d) directly to the polymerization reaction product, i.e., the polyacetal copolymer, without washing it, and melt-kneading the polyacetal copolymer, is used. With basic compounds other than these (d), the polymerization catalyst can be inactivated by melt-kneading in an extruder, but decomposition and removal of the unstable terminals is insufficient.
　さらには、塩基性化合物（ｄ）を使用した場合に、最終的に得られる組成物において、そのホルムアルデヒド発生量は特に低い値となり、より好ましい。 Furthermore, when a basic compound (d) is used, the amount of formaldehyde generated in the final composition is particularly low, which is more preferable.
　本実施形態において、上記の塩基性化合物（ｄ）は、１種類であってもよいし、２種以上を併用してもよく、それらの水和物や混合物、複塩等の状態であっても構わない。 In this embodiment, the basic compound (d) may be one type, or two or more types may be used in combination, and may be in the form of a hydrate, mixture, double salt, etc.
　本実施形態においては、上記の通り、重合触媒（ｃ）の使用量が少量であることから、当該重合触媒（ｃ）の失活剤である塩基性化合物（ｄ）の使用量も少量とすることができる。具体的には、重合生成物に対して１～１００ｐｐｍとすることができる。 In this embodiment, as described above, the amount of polymerization catalyst (c) used is small, so the amount of basic compound (d) used, which is a deactivator for the polymerization catalyst (c), can also be small. Specifically, it can be 1 to 100 ppm relative to the polymerization product.
　本実施形態においては、必要に応じて分子量調整剤を使用してもよい。分子量調整剤としては、線状ホルマール化合物が用いることができる。線状ホルマール化合物としては、メチラール、エチラール、ジブトキシメタン、ビス（メトキシメチル）エーテル、ビス（エトキシメチル）エーテル、ビス（ブトキシメチル）エーテル等が例示される。その中でも、メチラール、エチラール、及びジブトキシメタンからなる群より選択される１種以上であることが好ましい。 In this embodiment, a molecular weight regulator may be used as necessary. A linear formal compound can be used as the molecular weight regulator. Examples of linear formal compounds include methylal, ethylal, dibutoxymethane, bis(methoxymethyl) ether, bis(ethoxymethyl) ether, and bis(butoxymethyl) ether. Among these, it is preferable to use one or more compounds selected from the group consisting of methylal, ethylal, and dibutoxymethane.
　かかる重合及び失活処理の後、必要に応じて更に未反応モノマーの分離回収、乾燥等を従来公知の方法にて行う。 After this polymerization and deactivation treatment, if necessary, the unreacted monomers are separated and collected, dried, etc., using conventional methods.
　更に、本実施形態のポリアセタール共重合体の製造方法においては、重合する工程において、必要に応じて酸化防止剤を添加してもよい。 Furthermore, in the method for producing the polyacetal copolymer of this embodiment, an antioxidant may be added in the polymerization step as necessary.
　以下に、実施例により本実施形態をさらに具体的に説明するが、本実施形態は以下の実施例に限定されるものではない。 The present embodiment will be explained in more detail below using examples, but the present embodiment is not limited to the following examples.
［実施例１～１１、比較例１～２］
　重合反応装置として連続式二軸重合機を用いた。この重合機は、外側に加熱用又は冷却用の媒体を通すためのジャケットを備え、その内部には撹拌、推進及び粉砕用の多数のバドルを付した２本の回転軸が長手方向に設けられている。そして、重合機の２本の回転軸をそれぞれ２５０ｒｐｍで回転させながら、主モノマー（トリオキサン）及び表１に示すコモノマーを表１に示す割合で加えた。更に分子量調整剤としてメチラールを、得られた粗重合体のメルトフローレートが９．０ｇ／１０分となるように必要に応じて供給し、表１に示す重合触媒を表１に示す溶媒に溶解した溶液（水溶液：２０．０ｇ／Ｌ、ギ酸メチル：２．０ｇ／Ｌ，それ以外：１５．０ｇ／Ｌ）で重合触媒を触媒の添加量が全モノマーに対してギ酸メチル溶液では５ｐｐｍ、それ以外は１０ｐｐｍとなるように連続的に添加供給し塊状重合を行い、粉砕されて重合機から排出された粉末状の粗ポリアセタール共重合体を得た。その後、得られた粗ポリアセタール共重合体に、表１に示す失活剤（塩基性化合物）を２５ｐｐｍ添加して二軸押出機へ投入して溶融混練（シリンダー温度：２００℃）し、重合触媒を失活させた。この時、溶融混練の途中において、酸化防止剤としてＢＡＳＦジャパン（株）製、Irganox1010を０．３質量％及び熱安定剤としてメラミンを０．１質量％、それぞれ二軸押出機へ投入した。以上のようにしてポリアセタール共重合体のペレットを得た（比較例２を除く。）。
　一方、比較例２においては、実施例１と同様の操作により粗ポリアセタール共重合体を得た後、得られた粗ポリアセタール共重合体に、酸化防止剤としてＢＡＳＦジャパン（株）製、Irganox1010を０．３質量％及び失活剤としてメラミンを０．１質量％、それぞれ二軸押出機へ投入して溶融混練（シリンダー温度：２００℃）し、重合触媒を失活させ、ポリアセタール共重合体のペレットを得た。
　また、表１において、コモノマーは略号で示しているが、具体的には以下の通りである。
　ＤＯ：１，３－ジオキソラン
　ＢＤＦ：１，４－ブタンジオールホルマール
　さらに、表１において、触媒１及び２は以下の通りである。
　触媒１：リンタングステン酸（Ｈ３ＰＷ１２Ｏ４０）
　触媒２：リンモリブデン酸（Ｈ３ＰＭｏ１２Ｏ４０） [Examples 1 to 11, Comparative Examples 1 to 2]
A continuous twin-screw polymerization machine was used as the polymerization reaction apparatus. This polymerization machine was provided with a jacket for passing a heating or cooling medium on the outside, and two rotating shafts with many paddles for stirring, propulsion and crushing were provided in the longitudinal direction inside. Then, while rotating each of the two rotating shafts of the polymerization machine at 250 rpm, the main monomer (trioxane) and the comonomers shown in Table 1 were added in the ratios shown in Table 1. Furthermore, methylal was added as a molecular weight modifier as necessary so that the melt flow rate of the obtained crude polymer was 9.0 g/10 min, and the polymerization catalyst was continuously added and fed in a solution (aqueous solution: 20.0 g/L, methyl formate: 2.0 g/L, others: 15.0 g/L) in which the polymerization catalyst shown in Table 1 was dissolved in the solvent shown in Table 1 so that the amount of catalyst added was 5 ppm in the methyl formate solution and 10 ppm in the others with respect to the total monomer, and bulk polymerization was performed, and a powdery crude polyacetal copolymer was obtained which was crushed and discharged from the polymerization machine. Thereafter, 25 ppm of a deactivator (basic compound) shown in Table 1 was added to the obtained crude polyacetal copolymer, and the mixture was fed into a twin-screw extruder and melt-kneaded (cylinder temperature: 200° C.) to deactivate the polymerization catalyst. During the melt-kneading, 0.3 mass % of Irganox 1010 manufactured by BASF Japan Ltd. was fed into the twin-screw extruder as an antioxidant and 0.1 mass % of melamine as a heat stabilizer. In this manner, pellets of the polyacetal copolymer were obtained (except for Comparative Example 2).
On the other hand, in Comparative Example 2, a crude polyacetal copolymer was obtained by the same operation as in Example 1, and then 0.3 mass % of Irganox 1010 (manufactured by BASF Japan Ltd.) as an antioxidant and 0.1 mass % of melamine as a deactivating agent were added to the crude polyacetal copolymer obtained and melt-kneaded (cylinder temperature: 200° C.) to deactivate the polymerization catalyst, thereby obtaining pellets of the polyacetal copolymer.
In Table 1, the comonomers are shown by abbreviations, and specifically, they are as follows:
DO: 1,3-dioxolane BDF: 1,4-butanediol formal Further, in Table 1, catalysts 1 and 2 are as follows.
Catalyst 1: phosphotungstic acid (H 3 PW 12 O 40 )
Catalyst 2: Phosphomolybdic acid (H 3 PMo 12 O 40 )
［成形品外観評価］
　（評価方法）
　得られたポリアセタール共重合体ペレットを成形機（ＦＡＮＵＣ製射出成型機　Ｓ１００ｉＡ（φ３６））を用いて、φ１．５ｍｍのセンター１点ピンゲートの５０ｍｍ角で厚さ３ｍｍｔ平板を以下の条件で射出成形した。その後、成形品のゲート付近でのフローマークの大きさを測定し、外観評価を目視による５段階で評価した。
　（成形条件）
　シリンダー温度
　（ノズルヘッド）２００℃－２００℃－１８０℃－１７０℃（ホッパー側）
　金型温度：９０℃
　保圧：７５ＭＰａ
　射出時間：４．５秒
　射出条件：計量位置　２０ｍｍ、サックバック ５ｍｍ、Ｖ－Ｐ切り替え位置 ８ｍｍ　（評価）
　５：フローマークの大きさが６ｍｍ未満である
　４：フローマークの大きさが６ｍｍ以上８ｍｍ未満である
　３：フローマークの大きさが８ｍｍ以上１０ｍｍ未満である
　２：フローマークの大きさが１０ｍｍ以上１２ｍｍ未満である
　１：フローマークの大きさが１２ｍｍ以上である [Appearance evaluation of molded products]
(Evaluation method)
The obtained polyacetal copolymer pellets were injection molded into a 50 mm square, 3 mm thick plate with a φ1.5 mm center single pin gate under the following conditions using a molding machine (FANUC injection molding machine S100iA (φ36)). Thereafter, the size of the flow marks near the gate of the molded product was measured, and the appearance was visually evaluated on a 5-point scale.
(Molding condition)
Cylinder temperature (nozzle head) 200℃-200℃-180℃-170℃ (hopper side)
Mold temperature: 90°C
Holding pressure: 75 MPa
Injection time: 4.5 seconds Injection conditions: Metering position 20 mm, suck back 5 mm, VP switching position 8 mm (Evaluation)
5: The size of the flow mark is less than 6 mm. 4: The size of the flow mark is 6 mm or more and less than 8 mm. 3: The size of the flow mark is 8 mm or more and less than 10 mm. 2: The size of the flow mark is 10 mm or more and less than 12 mm. 1: The size of the flow mark is 12 mm or more.
［バーフロー］
　得られた共重合体ペレットを成形機（日精樹脂工業株式会社製射出成型機　ＥＳ３０００）を用いて、厚さが２ｍｍｔの評価用金型へ、ポリアセタール共重合体１～１６をそれぞれ射出して流動長を測定した。射出圧１００ＭＰａでの流動長（単位はｍｍ）を５段階で評価した。
　（成形条件）
　シリンダー温度
　（ノズルヘッド）１９５℃－１９５℃－１９５℃－１９５℃－１７５℃（ホッパー側）
　金型温度：８０℃
　射出速度：７０ｍｍ／ｓ
　射出圧：１００ＭＰａ
　（評価）
　５：流動長が４５０ｍｍ以上である
　４：流動長が４４０ｍｍ以上４５０ｍｍ未満である
　３：流動長が４３０ｍｍ以上４４０ｍｍ未満である
　２：流動長が４２０ｍｍ以上４３０ｍｍ未満である
　１：流動長が４２０ｍｍ未満である [Barflow]
The obtained copolymer pellets were injected into an evaluation mold having a thickness of 2 mm using a molding machine (injection molding machine ES3000 manufactured by Nissei Plastic Industrial Co., Ltd.) for each of the polyacetal copolymers 1 to 16, and the flow length was measured. The flow length (unit: mm) at an injection pressure of 100 MPa was evaluated on a 5-point scale.
(Molding condition)
Cylinder temperature (nozzle head) 195℃-195℃-195℃-195℃-175℃ (hopper side)
Mold temperature: 80°C
Injection speed: 70 mm/s
Injection pressure: 100 MPa
(evaluation)
5: The flow length is 450 mm or more. 4: The flow length is 440 mm or more and less than 450 mm. 3: The flow length is 430 mm or more and less than 440 mm. 2: The flow length is 420 mm or more and less than 430 mm. 1: The flow length is less than 420 mm.
［熱安定性（溶融体からのホルムアルデヒド発生量）］
　得られたポリアセタール共重合体のペレット５ｇを秤量し、２００℃に保ったシリンダーに充填して、５分間で溶融後、溶融物を密閉容器内に押し出した。この密閉容器に窒素ガスを流し、出てきた窒素ガスに含まれるホルムアルデヒドを水中に捕集した。この水中のホルムアルデヒド濃度をＪＩＳＫ０１０２　２９．１（２０１３）により測定することにより、溶融物からのホルムアルデヒドの質量を求めた。この質量を用いたポリアセタール共重合体の質量で除してホルムアルデヒド発生量（単位ｐｐｍ）とした。本方法によるホルムアルデヒド発生量は７０ｐｐｍ以下であることが実用上好ましい。 [Thermal stability (amount of formaldehyde generated from the melt)]
5 g of the obtained polyacetal copolymer pellets were weighed and filled into a cylinder kept at 200°C. After melting for 5 minutes, the melt was extruded into a sealed container. Nitrogen gas was passed through the sealed container, and formaldehyde contained in the nitrogen gas that came out was collected in water. The formaldehyde concentration in the water was measured according to JIS K0102 29.1 (2013) to determine the mass of formaldehyde from the melt. This mass was divided by the mass of the polyacetal copolymer used to obtain the amount of formaldehyde generated (unit: ppm). It is practically preferable that the amount of formaldehyde generated by this method is 70 ppm or less.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１より、実施例１～１１はいずれも成形時の流動性に優れる。同様に、実施例１～１１はいずれも成形品の外観評価が良好であり、成形品の表面性に優れることが分かる。また、ホルムアルデヒド発生量も少なく、熱安定性が高いことが分かる。
　これに対して、重合触媒をギ酸メチルに溶解した重合触媒溶液を用いた比較例１は、成形時の流動性及び成形品の表面性のいずれも劣っていた。また、比較例２は、塩基性化合物を使用せず、失活剤として粗ポリアセタール共重合体と同時に投入するメラミンを使用したため、不安定末端の除去ができず、熱安定性に劣っていた。 From Table 1, it can be seen that all of Examples 1 to 11 have excellent flowability during molding. Similarly, all of Examples 1 to 11 have good appearance evaluations of molded articles, and have excellent surface properties. In addition, it can be seen that the amount of formaldehyde generated is small, and the thermal stability is high.
In contrast, in Comparative Example 1, which used a polymerization catalyst solution in which a polymerization catalyst was dissolved in methyl formate, both the fluidity during molding and the surface properties of the molded product were poor. In Comparative Example 2, a basic compound was not used, and melamine was used as a deactivator, which was added simultaneously with the crude polyacetal copolymer, so that unstable terminals could not be removed, and the thermal stability was poor.

Claims (4)

  1. 　主モノマー（ａ）としてトリオキサンと、コモノマー（ｂ）として前記トリオキサンと共重合し得る化合物とを共重合する工程を含み、
    　前記工程において、重合触媒（ｃ）として、下記一般式（１）で表されるヘテロポリ酸を、活性水素を持つ溶媒の溶液として使用して共重合反応を行い、
    　共重合反応によって得られる粗ポリアセタール共重合体に塩基性化合物（ｄ）として、アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は第２族元素（Ｂｅを除く。）の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は１０ｇ／Ｌ水溶液のｐＨが１０以上の窒素含有有機化合物を添加して溶融混練を行う、ポリアセタール共重合体の製造方法。
    　Ｈｍ［Ｍ１ ｘ・Ｍ２ ｙＯＺ］・ｎＨ２Ｏ　　・・・一般式（１）
    〔一般式（１）中、Ｍ１はＰ、Ｓｉ、Ｂ及びＧｅより選択される元素からなる中心元素を表す。Ｍ２はＷ、Ｍｏ及びＶより選択される１種以上の配位元素を表す。ｘは１以上１０以下の整数を示し、ｙは６以上４０以下の整数を表し、ｚは１０以上１００以下の整数を表し、ｍは１以上の整数を表し、ｎは０以上５０以下の整数を表す。〕     The method includes a step of copolymerizing trioxane as a main monomer (a) and a compound copolymerizable with the trioxane as a comonomer (b),
    In the above step, a copolymerization reaction is carried out using a heteropolyacid represented by the following general formula (1) as a polymerization catalyst (c) in the form of a solution in a solvent having active hydrogen,
    A method for producing a polyacetal copolymer, comprising adding, as a basic compound (d), a carbonate, hydrogencarbonate or carboxylate of an alkali metal element or a hydrate thereof, a carbonate, hydrogencarbonate or carboxylate of a Group 2 element (excluding Be) or a hydrate thereof, or a nitrogen-containing organic compound having a pH of 10 or more in a 10 g/L aqueous solution to a crude polyacetal copolymer obtained by a copolymerization reaction, and melt-kneading the mixture.
    Hm [ M1x.M2yOz ] .nH2O General formula ( 1 )
    [In the general formula (1), M1 represents a central element selected from P, Si, B, and Ge. M2 represents one or more coordination elements selected from W, Mo, and V. x represents an integer of 1 or more and 10 or less, y represents an integer of 6 or more and 40 or less, z represents an integer of 10 or more and 100 or less, m represents an integer of 1 or more, and n represents an integer of 0 or more and 50 or less.]
  2. 　前記アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物、又は第２族元素（Ｂｅを除く。）の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物が、アルカリ金属元素の炭酸塩、炭酸水素塩若しくはカルボン酸塩又はその水和物である、請求項１に記載のポリアセタール共重合体の製造方法。 The method for producing a polyacetal copolymer according to claim 1, wherein the carbonate, hydrogen carbonate or carboxylate of an alkali metal element or a hydrate thereof, or the carbonate, hydrogen carbonate or carboxylate of a Group 2 element (excluding Be) or a hydrate thereof is a carbonate, hydrogen carbonate or carboxylate of an alkali metal element or a hydrate thereof.
  3. 　前記コモノマー（ｂ）が、１，３－ジオキソラン、ジエチレングリコールホルマール、１，４－ブタンジオールホルマール、１，３－ジオキサン、及びエチレンオキシドからなる群より選択される少なくとも１種である、請求項１又は２に記載のポリアセタール共重合体の製造方法。 The method for producing a polyacetal copolymer according to claim 1 or 2, wherein the comonomer (b) is at least one selected from the group consisting of 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, and ethylene oxide.
  4. 　前記ヘテロポリ酸が、リンモリブデン酸、リンタングステン酸、リンモリブドタングステン酸、リンモリブドバナジン酸、リンモリブドタングストバナジン酸、リンタングストバナジン酸、ケイタングステン酸、ケイモリブデン酸、ケイモリブドタングステン酸、及びケイモリブドタングストバナジン酸からなる群より選択される少なくとも１種である、　請求項１又は２に記載のポリアセタール共重合体の製造方法。 The method for producing a polyacetal copolymer according to claim 1 or 2, wherein the heteropolyacid is at least one selected from the group consisting of phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, and silicomolybdotungstovanadic acid.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09302055A (en) * 1996-05-17 1997-11-25 Polyplastics Co Production of copolyacetal
JPH115822A (en) * 1997-06-17 1999-01-12 Polyplastics Co Production of polyacetal copolymer
JPH1112337A (en) * 1997-06-27 1999-01-19 Polyplastics Co Production of polyacetal resin
JP2000191738A (en) * 1998-12-28 2000-07-11 Polyplastics Co Production of polyacetal copolymer
JP2019178187A (en) * 2018-03-30 2019-10-17 ポリプラスチックス株式会社 Method for producing polyacetal copolymer
JP6992144B1 (en) * 2020-10-20 2022-01-13 ポリプラスチックス株式会社 Method for producing polyacetal copolymer
WO2023171315A1 (en) * 2022-03-10 2023-09-14 ポリプラスチックス株式会社 Method for producing polyacetal copolymer

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09302055A (en) * 1996-05-17 1997-11-25 Polyplastics Co Production of copolyacetal
JPH115822A (en) * 1997-06-17 1999-01-12 Polyplastics Co Production of polyacetal copolymer
JPH1112337A (en) * 1997-06-27 1999-01-19 Polyplastics Co Production of polyacetal resin
JP2000191738A (en) * 1998-12-28 2000-07-11 Polyplastics Co Production of polyacetal copolymer
JP2019178187A (en) * 2018-03-30 2019-10-17 ポリプラスチックス株式会社 Method for producing polyacetal copolymer
JP6992144B1 (en) * 2020-10-20 2022-01-13 ポリプラスチックス株式会社 Method for producing polyacetal copolymer
WO2023171315A1 (en) * 2022-03-10 2023-09-14 ポリプラスチックス株式会社 Method for producing polyacetal copolymer

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