JP6383468B2 - Polyacetal resin composition - Google Patents

Description

  The present invention relates to a polyacetal resin composition.

Since polyacetal copolymers have balanced mechanical properties and excellent fatigue properties, they are widely used in parts such as automobiles, electronic devices, and electric devices. A polyacetal copolymer is produced by copolymerizing a cyclic acetal such as trioxane, which is formaldehyde or its cyclic trimer, and either or both of a cyclic ether and a cyclic formal. However, the polyacetal copolymer obtained by such copolymerization has — (OCH ₂ ) n—OH groups at some molecular terminals, and these terminal groups are thermally unstable. It is easily decomposed by the above and generates a large amount of formaldehyde, so it cannot be put into practical use as it is. That is, when a large amount of formaldehyde is generated, the resin foams at the time of molding, or a line from which gaseous formaldehyde is removed remains on the surface of the molded product, resulting in an inferior appearance. Further, the generated formaldehyde is oxidized by oxygen in the molding machine to become formic acid, and accelerates the main chain decomposition of the polyacetal copolymer. In particular, from the viewpoint that formaldehyde is an undesirable substance for the human body in recent years, a material having an extremely low amount of formaldehyde generated from a molded product has been demanded, and polyacetals having a small amount of formaldehyde have been invented.

  In recent years, in extremely demanding areas such as applications that come into contact with living organisms, there has been a demand for materials that suppress the amount of formaldehyde generated to a level much lower than conventional levels. In addition, not only formaldehyde but also acetaldehyde and further reduction of acrolein, which is highly toxic to microorganisms, have been demanded. Accordingly, there is an urgent need for materials that have extremely low amounts of acetaldehyde and acrolein as well as formaldehyde.

  Since polyacetal is generally low in stability due to heat or the like, it is generally a resin composition to which a heat stabilizer or the like is added. A small amount of formaldehyde generated from the polyacetal itself as the base resin is indispensable for obtaining a material having an extremely low amount of formaldehyde generated.

Polyacetal generates formaldehyde by having unstable terminal parts after polymerization. Known methods for stabilizing a polyacetal copolymer (hereinafter sometimes referred to as crude polyacetal) include a method of acetylating, etherifying, or urethanizing a terminal, and a method of decomposing an unstable terminal. ing.
Among them, a method of decomposing and stabilizing the unstable terminal portion is advantageous. As a method for decomposing this unstable terminal portion, a method of heating and stabilizing a crude polyacetal copolymer in water or in an organic solvent in the presence of a basic substance capable of decomposing this unstable terminal portion, A method of stabilizing a polyacetal copolymer in a heated and melted state is known. Whereas the method of heating and stabilizing the crude polyacetal copolymer in water or an organic solvent requires operations such as separation (filtration), recovery, and washing, the method of stabilizing in the heated and melted state is Since a directly stabilized polyacetal copolymer is obtained, this is the most industrially advantageous method.
As a conventionally known heat treatment method, a crude polyacetal copolymer is unstable due to heat treatment while maintaining a heterogeneous system in a medium in which the polyacetal copolymer does not dissolve (for example, water, water / methanol mixture). A method for removing a terminal portion is known (for example, Patent Document 1 and Patent Document 2). However, in this method, it is necessary to operate at a temperature close to the melting point of the polyacetal copolymer in order to increase the decomposition rate of the unstable end portion, and it is necessary to perform a long treatment to reduce the unstable end portion. was there. Even if such a treatment is performed, the obtained polyacetal copolymer does not have sufficient decomposition and removal of unstable end portions, and there is a problem that the polyacetal copolymer is likely to be colored by a long-time treatment at a high temperature. .

Further, Patent Document 3 discloses that the crude polyacetal copolymer is unstable by exposing it to a pressure of atmospheric pressure or higher at a temperature of 100 ° C. or higher in a saturated vapor mixture composed of a volatile organic solvent, a volatile base and water. A method for removing the end portion is disclosed. However, even with this method, removal of the unstable end portion was not sufficient. Further, a method is known in which a crude polyacetal copolymer is heated and kept in a molten state to decompose and remove unstable terminal portions.
For example, Patent Document 4 discloses a method of kneading a molten copolymer on a roll mill for a certain time, and Patent Document 5 or Patent Document 6 uses an extruder or the like in the presence of water, alcohol, or an alkali component. Patent Document 7 discloses a method for performing heat-melting treatment. Patent Document 7 discloses a method in which a crude polyacetal copolymer is heated and melted, and then an unstable portion is decomposed and removed under reduced pressure using a special surface renewal mixer. Is a single screw extruder for melting a crude polyacetal copolymer, a reaction agent comprising a crude polyacetal copolymer and a compound that forms hydroxide in the presence of water and water by the principle of flow splitting and rearrangement The reaction device is composed of a static mixer having a reaction zone that decomposes unstable parts while mixing with a vent, and a vented screw extruder for devolatilization placed immediately after the static mixer. In addition, Patent Document 9 discloses that a powdery or powdery crude polyacetal copolymer is treated under reduced pressure at a temperature 5 to 35 ° C. lower than the melting temperature and then heated in an extruder. Each method of melting treatment has been proposed.
Even if these crude polyacetal copolymers are heated and kept in a molten state, only a thermally unstable terminal portion can be decomposed and removed, so that considerable stabilization is possible. Polyacetal copolymers subjected to such treatment are practical. However, a thermally unstable end portion remains, which may cause an undesirable phenomenon such as generation of mold deposit (mold deposit) in the molding process. Therefore, a more stable polymer is strongly desired.

In these known methods, in order to increase the decomposition rate, the above-mentioned basic physical properties, alkali components, compounds that generate hydroxide in the presence of water, etc. (for example, amines widely used for this kind of application) Must be added to the polyacetal copolymer to increase the amount added. However, if the addition amount of amines or the like is increased too much, the polymer is colored. Furthermore, in order to reduce unstable terminal portions, it was necessary to perform treatment for a long time or a plurality of times. For this reason, the stabilized polyacetal copolymer not only deteriorates in color, but also increases the size and complexity of the apparatus. Furthermore, there is also a problem that decomposition and removal of unstable end portions of the crude polyacetal copolymer are not always sufficient.
In Patent Document 10, in order to solve these problems, as a stabilization method for obtaining a polyacetal copolymer having very few unstable terminal portions by a simple method, heat treatment is performed in the presence of a quaternary ammonium compound having a specific structure. It is disclosed to do below. According to this method, drastic stabilization of the thermally unstable terminal portion of the polyacetal copolymer can be realized and various problems associated with the above-described stabilization method can be solved. It has not yet been suppressed.

  Furthermore, Patent Document 11 discloses a stabilization method mainly using a quaternary ammonium compound of polyacrylic acid as a method for improving odor characteristics while removing unstable terminals. However, in this method, odor evaluation at a substantial processing temperature has not been achieved, and there remains a problem as odor evaluation at a processing temperature or higher. In addition, since polyacrylic acid has a high boiling point and remains in the polymer, it cannot be said that there is no concern about the colorability in addition to the decomposition behavior during heating, and the generation of acetaldehyde cannot be suppressed.

Japanese Patent Publication No. 40-10435, Japanese Patent Publication No.43-7553 Japanese Patent Publication No. 40-11627 Japanese Patent Publication No.39-8071 Japanese Patent Publication No. 43-1875 (corresponding to US Pat. No. 3,337,504) Japanese Patent Publication No. 44-11907 (corresponding to US Pat. No. 3,418,280) Japanese Patent Publication No. 58-11450 (corresponding to US Pat. No. 4,366,305) JP 58-152012 A (corresponding to European Patent No. 88,541) JP-A-62-129311 Japanese Patent No. 3087912 Patent No. 5031196

  Accordingly, an object of the present invention is to provide a high-purity polyacetal resin composition that generates little formaldehyde, acetaldehyde, and acrolein even when heat treatment such as heat melting is performed.

  As a result of intensive studies by the present inventor in order to solve the above problems, when a quaternary ammonium compound having a specific structure is coexisted with polyacetal, formaldehyde, acetaldehyde, and acrolein can be obtained even when heat melting such as molding is performed. As a result, the inventors have found that there is little occurrence of the occurrence of the problem and have completed the present invention.

That is, the present invention is as follows.
[1] A polyacetal resin composition comprising a polyacetal (A) and a quaternary ammonium compound (B) represented by the following formula (1).
[(R1) _m (R2) _4-m N ⁺ ] _n X ⁿ⁻ (1)
(In formula (1), each R1 is independently an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; an unsubstituted alkyl group having 1 to 30 carbon atoms. Or an aralkyl group in which the substituted alkyl group is substituted with at least one aryl group having 6 to 20 carbon atoms; or an aryl group having 6 to 20 carbon atoms is an unsubstituted alkyl group having 1 to 30 carbon atoms or a substituted group Represents an alkylaryl group substituted with an alkyl group, the unsubstituted alkyl group and the substituted alkyl group are linear, branched or cyclic, and the substituents of the substituted alkyl group are halogen, hydroxyl group, aldehyde group, carboxyl Group, amino group, or amide group, and an unsubstituted alkyl group, an aryl group, an aralkyl group, and an alkylaryl group may have a hydrogen atom substituted with a halogen atom. Good.
R2 independently represents a group represented by the following formula having 2 to 60 carbon atoms and 2 to 30 oxygen atoms.
-(RO) k-H (wherein R represents a substituted or unsubstituted alkyl group, and k represents a natural number of 2 or more)
m and n represent an integer of 1 to 3.
X is a hydroxyl group or an acid residue of a compound selected from the group consisting of a monocarboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid, an inorganic thioacid, and an organic thioacid having 1 to 20 carbon atoms. Represents a group containing no nitrogen atom. )
[2] The polyacetal resin composition according to [1], wherein the nitrogen concentration n derived from the quaternary ammonium compound (B) represented by the following formula (2) is 0.1 ppb or more and 30 ppm or less on a mass basis.
n = P × 14 / Q (2)
(Wherein P represents the amount of quaternary ammonium compound (B) relative to the total amount of polyacetal and quaternary ammonium compound (B) (mass ppb or ppm), 14 is the atomic weight of nitrogen, and Q is Represents the molecular weight of the quaternary ammonium compound (B).)
[3] The polyacetal resin composition according to [1] or [2], wherein X in formula (1) is an acid residue of a monocarboxylic acid.
[4] The polyacetal resin composition according to [3], wherein the monocarboxylic acid is at least one selected from the group consisting of formic acid, acetic acid, and propionic acid.
[5] The polyacetal resin composition according to any one of [1] to [4], wherein R2 in Formula (1) has 2 to 6 carbon atoms.
[6] A method for producing a stabilized polyacetal, comprising a step of heat-treating a polyacetal having a thermally unstable terminal portion in the presence of a quaternary ammonium compound (B) represented by the following formula (1). [(R1) _m (R2) _4-m N ⁺ ] _n X ⁿ⁻ (1)
(In formula (1), each R1 is independently an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; an unsubstituted alkyl group having 1 to 30 carbon atoms. Or an aralkyl group in which the substituted alkyl group is substituted with at least one aryl group having 6 to 20 carbon atoms; or an aryl group having 6 to 20 carbon atoms is an unsubstituted alkyl group having 1 to 30 carbon atoms or a substituted group Represents an alkylaryl group substituted with an alkyl group, wherein the unsubstituted alkyl group or the substituted alkyl group is linear, branched or cyclic, and the substituents of the substituted alkyl group are halogen, hydroxyl group, aldehyde group, carboxyl A non-substituted alkyl group, an aryl group, an aralkyl group, and an alkylaryl group, wherein a hydrogen atom is substituted with a halogen. Also good.
R2 independently represents a group represented by the following formula having 2 to 60 carbon atoms and 2 to 30 oxygen atoms.
-(RO) k-H (wherein R represents a substituted or unsubstituted alkyl group, and k represents a natural number of 2 or more)
m and n represent an integer of 1 to 3.
X is a hydroxyl group or an acid residue of a compound selected from the group consisting of a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid, an inorganic thioacid, and an organic thioacid having 1 to 20 carbon atoms, A group not containing a nitrogen atom is represented.
[7] The heat treatment is performed in the presence of a quaternary ammonium compound represented by the above formula (1) and a quaternary ammonium compound (C) represented by the following formula (3). ] Method.
[R3R4R5R6N ⁺ ] _l Y ^l− (3)
(In Formula (3), R3, R4, R5, and R6 are each independently an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; and 1 to 30 carbon atoms. Or an aralkyl group in which the substituted alkyl group is substituted with at least one aryl group having 6 to 20 carbon atoms; or the aryl group having 6 to 20 carbon atoms is at least one non-alkyl group having 1 to 30 carbon atoms Represents a substituted alkyl group or an alkylaryl group substituted with a substituted alkyl group, and the unsubstituted alkyl group and the substituted alkyl group are linear, branched, or cyclic, and the substituent of the substituted alkyl group is a halogen, a hydroxyl group An aldehyde group, a carboxyl group, an amino group, or an amide group, and an unsubstituted alkyl group, an aryl group, an aralkyl group, and an alkylaryl group have a hydrogen atom as a halogen atom. May be substituted.
l represents an integer of 1 to 3.
Y represents a hydroxyl group or an acid residue of a compound selected from the group consisting of a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid, an inorganic thioacid, and an organic thioacid having 1 to 20 carbon atoms. )

  ADVANTAGE OF THE INVENTION According to this invention, the polyacetal resin composition with few generation | occurrence | production of formaldehyde, acetaldehyde, and acrolein can be provided.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

<Polyacetal (A)>
The polyacetal (A) used in the present embodiment is a polymer having an oxymethylene group in the main chain, and specific examples thereof include formaldehyde monomers or their trimers (trioxane) and tetramers (tetraoxane). Obtained by copolymerizing cyclic oligomers of formaldehyde with cyclic ethers such as ethylene oxide, propylene oxide, epichlorohydrin, glycols such as 1,3-dioxolane and 1,4-butanediol formal, and cyclic formals of diglycol. The resulting polyacetal copolymer can be given as a representative example.
Moreover, the polyacetal copolymer which has a branch obtained by copolymerizing monofunctional glycidyl ether, and the polyacetal copolymer which has a crosslinked structure obtained by copolymerizing polyfunctional glycidyl ether can also be used.
Furthermore, a polyacetal homopolymer having a block component obtained by polymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde in the presence of a compound having a functional group such as a hydroxyl group at both ends or one end, for example, polyalkylene glycol, A compound having a functional group such as a hydroxyl group at both ends or one end, for example, a formaldehyde monomer or a cyclic oligomer of formaldehyde such as a trimer (trioxane) or tetramer (tetraoxane) in the presence of hydrogenated polybutadiene glycol; A polyacetal copolymer having a block component obtained by copolymerizing cyclic ether or cyclic formal can also be used.
As described above, in the present embodiment, any polyacetal homopolymer or copolymer can be used as the polyacetal.

Incidentally, the polyacetal is generally thermally unstable end - Includes (-CH ₂ OH group or a (OCH ₂₎ group containing n-OH hydroxymethyl group such as), therefore, subjected to a heat And formaldehyde, and in some cases acetaldehyde and acrolein. In this embodiment, the quaternary ammonium compound (B) represented by the formula (1) is used to decompose and remove the unstable terminal portion of the polyacetal during heating, thereby suppressing the generation of formaldehyde and the like.
In particular, since the polyacetal copolymer contains many unstable terminal portions, the resin composition of this embodiment is effective when the polyacetal is a copolymer.

Therefore, the polyacetal copolymer will be described in detail below.
The ratio of comonomer such as 1,3-dioxolane in the polyacetal copolymer is generally 0.01 to 60 mol%, preferably 0.03 to 20 mol%, more preferably 0.05 to 20 mol% with respect to 1 mol of trioxane. 15 mol%, most preferably 0.1 to 10 mol% is used.
The polymerization catalyst used when polymerizing the polyacetal copolymer is not particularly limited, but cationically active catalysts such as Lewis acids, proton acids and esters or anhydrides thereof are preferred.
Examples of the Lewis acid include boric acid, tin, titanium, phosphorus, arsenic and antimony halides. Specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, pentachloride. Examples thereof include phosphorus, antimony pentafluoride, and complex compounds or salts thereof.
Specific examples of the protonic acid, its ester or anhydride include perchloric acid, trifluoromethanesulfonic acid, perchloric acid-tertiary butyl ester, acetyl perchlorate, isopolyacids, heteropolyacids, trimethyloxonium hexafluorophosphate, etc. Is mentioned.
Among these, boron trifluoride; boron trifluoride hydrate; and a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride are preferable. Specifically, boron trifluoride diethyl ether is used. Boron trifluoride di-n-butyl ether can be mentioned as a preferred example.
The polymerization method of the polyacetal copolymer is not particularly limited, and is generally carried out by bulk polymerization, and can be either batch type or continuous type.
As the polymerization apparatus, for example, a self-cleaning type extrusion kneader such as a kneader, a twin screw type continuous extrusion kneader, a twin screw paddle type continuous mixer can be used, and a monomer in a molten state is supplied to the polymerization machine, A solid agglomerated polyacetal copolymer is obtained as the polymerization proceeds.

<Quaternary ammonium compound (B)>
In the present embodiment, the quaternary ammonium compound (B) is represented by the following formula (1).
[(R1) _m (R2) _4-m N ⁺ ] _n X ⁿ⁻ (1)
In the formula, each R 1 independently represents an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; An aralkyl group substituted with at least one aryl group having 6 to 20 carbon atoms; or an aryl group having 6 to 20 carbon atoms substituted with at least one unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms. An unsubstituted alkyl group or a substituted alkyl group is linear, branched, or cyclic, and the substituent of the substituted alkyl group is a halogen, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, or It is an amide group, and in the unsubstituted alkyl group, aryl group, aralkyl group and alkylaryl group, a hydrogen atom may be substituted with a halogen.
R2 independently represents a group represented by the following formula having 2 to 60 carbon atoms and 2 to 30 oxygen atoms.
-(RO) k-H (wherein R represents a substituted or unsubstituted alkyl group, and k represents a natural number of 2 or more)
m and n represent an integer of 1 to 3. Since the possibility of side reactions increases as n increases, it is particularly preferable that n is 1 in order to obtain a high-purity product and from the viewpoint of availability.
X is a hydroxyl group or an acid residue of a compound selected from the group consisting of a monocarboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid, an inorganic thioacid, and an organic thioacid having 1 to 20 carbon atoms. Represents a group containing no nitrogen atom. When X contains a nitrogen atom, it does not work effectively to suppress the generation of acetaldehyde and acrolein during heating.

  In Formula (1), R1 is preferably an alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 2 to 4 carbon atoms from the viewpoint of availability and ease of production.

Moreover, in Formula (1), R2 represents the group represented by the following formula | equation whose carbon number is 2-60 and oxygen number is 2-30 each independently.
-(RO) k-H (wherein R represents a substituted or unsubstituted alkyl group, and k represents a natural number of 2 or more)
By selecting such a group as R2, generation of formaldehyde, acetaldehyde and acrolein from the polyacetal when high-temperature heating such as heating and melting is performed can be suppressed.
If the number of carbons exceeds 60 or the number of oxygens exceeds 30, it may take time to isolate and produce the quaternary ammonium compound.
From the viewpoint of the synthesis of the quaternary ammonium compound, R2 preferably has 2 to 10 carbon atoms and 2 to 5 oxygen atoms, and from the viewpoint of colorability after melting and heating, it has 2 to 6 carbon atoms and oxygen. More preferably, the number is 2-3.

  In the formula (1), X is preferably an acid residue of a monocarboxylic acid from the viewpoint of availability. Among these, at least one acid residue selected from the group consisting of formic acid, acetic acid, and propionic acid is preferable because of ease of handling.

The concentration of the quaternary ammonium compound (B) represented by the formula (1) in the polyacetal resin composition of the present embodiment is the same as that of the quaternary ammonium compound (B) represented by the following formula (2). It is preferably 0.1 ppb or more and 30 ppm or less in terms of mass in terms of the concentration n of nitrogen derived.

When it is 0.1 ppb or more, acrolein can be effectively suppressed, and when it is 30 ppm or less, generation of acetaldehyde and yellowing of the polyacetal resin can be effectively suppressed. A more preferable range is 0.01 ppm or more and 10 ppm or less, still more preferably 0.01 ppm or more and 8 ppm, and most preferably 0.03 ppm to 6 ppm.

The nitrogen conversion content n of the quaternary ammonium compound (B) is represented by the following formula (2).
n = P × 14 / Q (2)
(In the formula, P represents the amount (mass ppb or ppm) of the quaternary ammonium compound (B) represented by the formula (1) relative to the total mass of the polyacetal (A) and the quaternary ammonium compound (B). 14 represents the atomic weight of nitrogen, and Q represents the molecular weight of the quaternary ammonium compound (B).)
Here, the content of the quaternary ammonium compound (B) is defined in terms of nitrogen as the quaternary ammonium compound (B) contained in the resin composition depending on the molecular weight of the quaternary ammonium compound (B). This is for avoiding a large change in the number of moles.

In addition, the amount of nitrogen derived from the quaternary ammonium compound (B) in the polyacetal resin composition can be quantified by, for example, NMR analysis as follows, and 15 kg of polyacetal resin composition pellets can be linlex mill or the like After freezing and pulverizing, put in a 100 L SUS autoclave with a stirrer and add 50 L of distilled water. Then, it is placed in an oven set at 120 ° C., allowed to stand for 24 hours and then brought to room temperature, and solid liquid separation is performed by suction filtration. The obtained liquid is concentrated with an evaporator, and about 2.5 ml of liquid concentrated to about 5 ml and heavy water mixed at 1: 1 (volume ratio) are subjected to NMR analysis, and near 3.5 ppm and 3.9 ppm. The amount of nitrogen derived from the quaternary ammonium compound (B) is quantified from the nearby peak area.
In addition, when it is clear that the nitrogen source is only the quaternary ammonium compound (B), by quantifying the amount of nitrogen atoms with a nitrogen analyzer (for example, a nitrogen analyzer TN-2100H manufactured by Mitsubishi Analytech) It can also be quantified.

As described above, according to the resin composition of the present embodiment, generation of formaldehyde and the like due to heat treatment can be reduced even when a polyacetal having an unstable terminal group is used.
Further, the polyacetal can be produced in a previously stabilized form (as a stabilized polyacetal) instead of being used in the form of such a resin composition.

Hereinafter, a method for producing a stabilized polyacetal (a method for stabilizing a polyacetal having an unstable terminal group) in this embodiment will be described with reference to specific examples.
In the present embodiment, the polyacetal having a thermally unstable terminal portion is heat-treated in the presence of the quaternary ammonium compound represented by the above formula (1). Here, although there is no limitation in the aspect of heat processing, the following two can be mentioned, for example.
One is to heat and melt the crude polyacetal in the presence of the quaternary ammonium compound (B), and the other is to dissolve the crude polyacetal in the presence of the quaternary ammonium compound (B). It heats in a slurry state.

First, the heat treatment in the case where the crude polyacetal is melted will be described.
The crude polyacetal can be melted by, for example, a single screw extruder with a vent, a twin screw extruder with a vent, or the like. The heat treatment is preferably performed at a temperature which is not lower than the melting point of polyacetal and not higher than 260 ° C. If it exceeds 260 ° C., there may be a problem of coloring and a problem of decomposition (reduction in molecular weight) of the polymer main chain. In this case, before melting the crude polyacetal, the quaternary ammonium compound (B) may be added to the crude polyacetal in advance, or after melting the crude polyacetal, the quaternary ammonium compound (B) is added, You may add to the melted crude polyacetal.

  Examples of the method of adding the quaternary ammonium compound (B) to the crude polyacetal before melting include, for example, water or an organic solvent capable of dissolving the quaternary ammonium compound (B), specifically, a lower aliphatic alcohol. Etc. (for example, methanol), a solution in which the quaternary ammonium compound (B) is dissolved may be added after adding 0.1 to 5 mass% with respect to the crude polyacetal. In this case, the mixing may be performed using a general solid mixer such as a horizontal cylindrical type, a V type, a ribbon type, a paddle type, or a high-speed flow type. Further, the extruder main body is added until the solution containing the quaternary ammonium compound (B) is directly added to the chute portion for supplying the polyacetal to the extruder or until the polyacetal is melted from the supply port of the extruder. It may be added directly to.

Another method for adding the quaternary ammonium compound (B) in advance to the crude polyacetal before melting is, for example, water or the above organic solvent (for example, lower fat such as methanol) of the quaternary ammonium compound (B). A method in which a crude polyacetal is introduced into a solution of a group alcohol) to form a slurry once, and the slurry is filtered and dried to leave the quaternary ammonium compound (B) in the polyacetal before melting. it can. In this case, the solvent used for the solution is preferably a solvent that does not dissolve the crude polyacetal. By using such a solvent, post-treatment such as filtration and drying can be easily performed.
The amount of the quaternary ammonium compound (B) used relative to the total mass of the crude polyacetal and the quaternary ammonium compound (B) depends on the concentration of the quaternary ammonium compound (B) in the solution and the content of the polyacetal after filtration. By controlling the liquid ratio, it can be controlled to a specific usage amount.
By the above method, the crude polyacetal to which a predetermined amount of the quaternary ammonium compound (B) has been added is either as it is or, if necessary, dried and then melted by an extruder or the like and subjected to heat treatment. At the time of melting, it may be stabilized by adding at least one of amines, which are conventionally known decomposition accelerators, water, methanol, etc., or subjected to heat treatment without adding anything else. May be. It is preferable to add 0.1-5 mass parts with respect to 100 mass parts of polyacetals about the addition amount of decomposition accelerators conventionally used, such as amines, water, methanol, etc. Moreover, you may further add a quaternary ammonium compound (B) as needed. These decomposition accelerators such as amines, water, methanol, and the quaternary ammonium compound (B) can be added alone or in combination of two or more.

On the other hand, as a method of adding the quaternary ammonium compound (B) to the molten crude polyacetal after melting the crude polyacetal, water or an organic solvent capable of dissolving the quaternary ammonium compound (B), specifically For example, a solution in which the quaternary ammonium compound (B) is dissolved in a lower aliphatic alcohol or the like (for example, methanol) is added, or the quaternary ammonium compound (B) and water or a quaternary ammonium compound are added. The organic solvent that can dissolve (B) can be added separately to the polyacetal melted by an extruder or the like.
The addition amount of an organic solvent such as water or methanol is preferably about 0.1 to 5 parts by mass with respect to 100 parts by mass of the crude polyacetal. In addition to the quaternary ammonium compound (B), conventionally known amines, a quaternary ammonium compound (C) described later, and the like may be added.

In the present embodiment, the amount of the quaternary ammonium compound (B) used in the heat treatment step is not limited, but the nitrogen concentration n derived from the quaternary ammonium compound (B) represented by the following formula (2 ′ ″) In terms of ''', it is preferably 0.1 mass ppb to 30 mass ppm, more preferably 0.01 mass ppm to 25 mass ppm, still more preferably 1 mass ppm to 20 mass ppm, especially Preferably, it is 5 ppm to 10 ppm.
n ′ ″ = P ′ ″ × 14 / Q ′ ″ (2 ′ ″)
(In the formula, P ′ ″ represents the amount (mass ppb or ppm) relative to the total mass of the crude polyacetal and quaternary ammonium compound (B) of the quaternary ammonium compound (B), and 14 is the atomic weight of nitrogen. Q ′ ″ represents the molecular weight of the quaternary ammonium compound.)
When the nitrogen concentration n ′ ″ derived from the quaternary ammonium compound (B) is 0.1 mass ppb or more, the unstable terminal portion can be decomposed in a short time, and when it is 30 mass ppm or less, Even after stabilization, the color tone of the polyacetal is not impaired. Here, the reason why the concentration of the quaternary ammonium compound (B) is converted into a nitrogen concentration is to avoid depending on the molecular weight of the quaternary ammonium compound (B) as described above. .

Next, heat treatment in the case where the crude polyacetal is not melted and performed in a slurry state will be described.
As such heat treatment, for example, the polyacetal is put into a solution in which the quaternary ammonium compound (B) is dissolved in a medium in which the polyacetal is not dissolved, and heat treatment is performed in a slurry state where the polyacetal is not melted. List the processes.
In this case, a solvent that does not dissolve the crude polyacetal is used as the solvent used in the solution, as described above, by using such a solvent, post-treatment such as filtration and drying can be easily performed. Because it becomes. Examples of the medium that does not dissolve the polyacetal include water and an aqueous solution containing about 10 to 30% by mass of methanol. Although there is no limitation in heating temperature, it is preferable to carry out at the temperature which is 80 degreeC or more and is less than melting | fusing point of polyacetal.
Moreover, 5-50 mass% is normally selected as the density | concentration (slurry density | concentration) of the polyacetal in a slurry. When the slurry concentration is less than 5% by mass, a large amount of a medium that does not dissolve polyacetal is required, and the apparatus becomes large. On the other hand, if the slurry concentration exceeds 50% by mass, the stirring and mixing becomes insufficient, and a problem arises that the polyacetal is settled and the slurry is separated into two phases.

At this time, the concentration of the quaternary ammonium compound (B) in the solution in which the quaternary ammonium compound (B) is dissolved in a medium in which the polyacetal copolymer is not dissolved is expressed by the following formula (2 ″). In terms of the nitrogen concentration n ″ derived from the quaternary ammonium compound (B), it is preferably 0.5 mass ppb to 500 mass ppm, more preferably 0.05 to 500 mass ppm, still more preferably 1 to 1. 300 ppm by mass.
n ″ = P ″ × 14 / Q ″ (2 ″)
(Wherein P ″ represents the concentration (mass ppb or ppm) of the quaternary ammonium compound (B) in the solution, 14 represents the atomic weight of nitrogen, and Q ″ represents the molecular weight of the quaternary ammonium compound. .)
When the nitrogen concentration n ″ derived from the quaternary ammonium compound (B) is 0.5 mass ppb or more, the unstable terminal portion can be decomposed in a short time, and when it is 500 mass ppm or less, the stability is stable. Even after conversion, the color tone of the polyacetal is not impaired.
Here, the reason why the concentration of the quaternary ammonium compound (B) is converted into a nitrogen concentration is to avoid depending on the molecular weight of the quaternary ammonium compound (B) as described above. .
In addition, even if the amines used conventionally, the below-mentioned quaternary ammonium compound (C), etc. are added to the solution which melt | dissolved the quaternary ammonium compound (B) in the medium which does not melt | dissolve a polyacetal. Good.

In the case where the crude polyacetal is stabilized in a slurry state without melting, the polyacetal after the heat treatment is subjected to filtration and washing as a post-treatment, after removing formaldehyde and unreacted monomers generated by decomposition from the terminal portion. Dried. In the case of stabilization in a molten state, the polyacetal after heat treatment is pelletized after removing the above-mentioned formaldehyde, unreacted monomer, excess quaternary ammonium compound (B), etc. from the vent under reduced pressure. .
The obtained stable polyacetal is made of an antioxidant, a formaldehyde scavenger, a formic acid scavenger, an ultraviolet absorber, a light stabilizer, a release agent, a reinforcing material, an electric material, a thermoplastic resin, a thermoplastic elastomer, and a pigment as necessary. After being mixed with one or more compounding agents such as an extruder or the like, it is put into practical use. There are no particular restrictions on the compounding time of the compounding agent, and depending on the type, for example, it may be added in advance to the crude polyacetal before the unstable terminal part is decomposed and removed. You may add to the polyacetal decomposed and removed.

Next, the terminal group contained in the polyacetal in this embodiment is described.
In the present embodiment, as a terminal group as a whole of the plurality of polyacetal (co) polymer chains constituting the polyacetal, a hydroxymethyl group such as the above-described —CH ₂ OH group or — (OCH ₂ ) _n —OH group is used. In addition to the containing group, an alkoxyl group such as a methoxyl group (—OCH ₃ ), a hydroxyalkyl group such as a hydroxyethyl group (—CH ₂ CH ₂ OH), and a formate group can be mentioned.
The terminal alkoxyl group is generally formed by formal, which is a molecular weight modifier added in the polymerization stage. For example, when methylal ((CH ₃ O) ₂ CH ₂ ) is used as a molecular weight modifier, a methoxyl group is formed as a terminal group. The carbon number of the terminal alkoxyl group is generally 1 to 10 carbon atoms and preferably 1 to 3 carbon atoms from the viewpoint of synthesis and purification of formal which is a molecular weight modifier.

A terminal hydroxyalkyl group such as a hydroxyethyl group or a hydroxybutyl group is generally derived from the aforementioned cyclic ether or cyclic formal used as a raw material comonomer of polyacetal, and is formed in the following process.
That is, when polymerizing a polyacetal in which an oxyalkylene group derived from a cyclic ether or a cyclic formal is inserted during repetition of a polyacetal unit, first, a thermally unstable terminal hydroxy group is generated by a small amount of water in the raw material. A methyl group (—CH ₂ OH) is formed. This unstable portion at the end is decomposed by the stabilization treatment, and this decomposition proceeds inward in the main chain containing the polyacetal unit and the oxyalkylene unit, and reaches the site of the oxyalkylene unit. The alkylene unit is converted to a stable terminal hydroxyalkyl group such as a hydroxyethyl group or a hydroxybutyl group. The number of carbon atoms of the hydroxyalkyl group is at least 2, and preferably 2 to 10 from the viewpoint of synthesis and purification of cyclic ether and cyclic formal.
On the other hand, when a hydroxymethyl group is present as a terminal group in polyacetal, the hydroxymethyl group is eliminated from the terminal by heating during molding to form formaldehyde. Therefore, if many terminal hydroxymethyl groups are present, the formaldehyde produced is excessive.
In the present embodiment, it is considered that this terminal hydroxymethyl group is decomposed and removed by the action of the quaternary ammonium compound (B), thereby suppressing the formation of formaldehyde.
Further, in the present embodiment, the quaternary ammonium compound (B) contains a trace amount of formaldehyde generated from a trace amount of unstable terminal remaining in the polyacetal in addition to the above-mentioned decomposition removal of the terminal hydroxymethyl group, It is also involved in polymerizing acetaldehyde and acrolein by anionic polymerization during cooling after heating and melting such as molding and immobilizing it in a polyacetal resin composition, which also reduces the generation of formaldehyde, acetaldehyde, acrolein, etc. it is conceivable that.
However, the mechanism of the effect of this embodiment is not limited to these.

  In this embodiment, the stabilization of the polyacetal may be performed after the polymerization catalyst remaining in the crude polyacetal obtained by the polymerization reaction is deactivated, or without deactivation of the polymerization catalyst. May be. Furthermore, the stabilization method of the present embodiment can also be applied to polyacetal that has been subjected to a known stabilization treatment but still has unstable end portions.

The deactivation of the polymerization catalyst is carried out by converting the crude polyacetal obtained by the polymerization reaction into amines such as ammonia, triethylamine, tri-n-butylamine, or alkali metal or alkaline earth metal hydroxides, inorganic acid salts, organic acids. It can carry out by throwing in the aqueous solution or organic solvent solution containing at least 1 type of catalyst neutralization deactivators, such as a salt, and generally stirring for several minutes-several hours in a slurry state. In this case, the slurry after deactivation of the catalyst neutralization is dried after the unreacted monomer, the catalyst neutralization deactivator and the catalyst neutralization salt are removed by filtration and washing.
In addition, the polymerization catalyst is deactivated by contacting a vapor such as ammonia or triethylamine with a crude polyacetal, or at least one of hindered amines, triphenylphosphine, calcium hydroxide, etc. and the crude polyacetal are contacted with a mixer. It is also possible to use a method of deactivating the catalyst. In addition, the stabilization method of the present embodiment using polyacetal in which the polymerization catalyst is reduced in volatilization by heating in an inert gas atmosphere at a temperature not higher than the melting point of the crude polyacetal without deactivation of the polymerization catalyst. May be performed.
The above-described deactivation operation of the polymerization catalyst and the volatilization reduction operation of the polymerization catalyst may be performed after pulverizing the crude polyacetal obtained by the polymerization reaction, if necessary.

In the present embodiment, the quaternary ammonium compound (B) is not particularly limited as long as it is represented by the formula (1).
For example, 1-hydroxymethoxy-N-((hydroxymethoxy) methyl) -N, N-dimethylmethaneammonium, 2- (2-hydroxyethoxy) -N- (2- (2-hydroxyethoxy) ethyl) -N, N-dimethylethane-1-ammonium, N-ethyl-N, N-bis ((hydrowood methoxy) methyl) ethaneammonium, 2- (2-hydroxyethoxy) -N- (2- (2-hydroxyethoxy) ethyl) -N , N-dimethylethane-1-ammonium, N, N, N-triethyl-2- (2- (2-hydroxy) ethoxy) ethane-1-ammonium, N- (2- (2- (hydrowood methoxy) ethoxy) ethyl)- N, N-dipropylpropane-1-ammonium, N-(((hydroxymethoxy) methoxy) methyl) -N, N- Hydroxides such as propylpropane-1-ammonium, N- (2- (2- (2-hydroxyethoxy) ethoxy) ethyl) -N, N-dipropylpropane-1-ammonium; hydrochloric acid, odorous acid, fluorine Hydroacid salts such as acids; sulfuric acid, phosphoric acid nitrate, carbonic acid, boric acid, chloric acid, iodic acid, silicic acid, perchloric acid, chlorous acid, hypochlorous acid, chlorosulfuric acid, amidosulfuric acid, disulfuric acid, tripolyphosphoric acid, etc. Oxo acid salts of thiosulfates; monocarboxylic acid salts such as formic acid, acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid, caproic acid, caprylic acid, capric acid, benzoic acid, etc. It is done.
Of these, the hydroxide is a strong alkali and needs to be handled with care, and is therefore preferably used in the form of a salt, particularly preferably a monocarboxylate.

Moreover, in this embodiment, when stabilizing polyacetal, the quaternary ammonium compound (C) represented by following formula (3) can be used with the said quaternary ammonium compound (B).
[R3R4R5R6N ⁺ ] _l Y ^l− (3)
Wherein R 3, R 4, R 5 and R 6 are each independently an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; an unsubstituted group having 1 to 30 carbon atoms An aralkyl group in which an alkyl group or a substituted alkyl group is substituted with at least one aryl group having 6 to 20 carbon atoms; or an aryl group having 6 to 20 carbon atoms is an unsubstituted alkyl group having 1 to 30 carbon atoms Or an alkylaryl group substituted with a substituted alkyl group, wherein the unsubstituted alkyl group and the substituted alkyl group are linear, branched, or cyclic, and the substituent of the substituted alkyl group is a halogen, hydroxyl group, aldehyde group A carboxyl group, an amino group, or an amide group, and the unsubstituted alkyl group, aryl group, aralkyl group, and alkylaryl group have a hydrogen atom substituted with a halogen atom. It may be.
l represents an integer of 1 to 3.
Y represents a hydroxyl group or an acid residue of a compound selected from the group consisting of a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid, an inorganic thioacid, and an organic thioacid having 1 to 20 carbon atoms.

Examples of such quaternary ammonium compounds (C) include tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6-hexamethylenebis. (Trimethylammonium), decamethylene-bis- (trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl (2-hydroxy) Ethyl) ammonium, tri-n-butyl (2-hydroxyethyl) ammonium, trimethylbenzylammonium, triethylbenzylammonium, tri Lopylbenzylammonium, tri-n-butylbenzylammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, octadecyltri (2-hydroxyethyl) Hydroxides such as ammonium and tetrakis (hydroxyethyl) ammonium; Hydrochloric acid salts such as hydrochloric acid, odorous acid and hydrofluoric acid; sulfuric acid, nitric acid phosphoric acid, carbonic acid, boric acid, chloric acid, iodic acid, silicic acid, perchloric acid, Oxo acid salts such as chlorous acid, hypochlorous acid, chlorosulfuric acid, amidosulfuric acid, disulfuric acid and tripolyphosphoric acid; thioic acid salts such as thiosulfuric acid; formic acid, acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid, Caproic acid, caprylic acid, capri Acid, benzoic acid, a carboxylic acid salt such as oxalic acid. Of these, the hydroxide is a strong alkali and needs to be handled with care, so it is preferably used in the form of a salt, particularly preferably a carboxylate.
In the present embodiment, together with the quaternary ammonium compound (B), the quaternary ammonium compound (C) may be used alone or in combination of two or more.

In the present embodiment, the stabilization of polyacetal can be performed by appropriately using conventionally known apparatuses and operation methods.
In the present embodiment, conventionally known amines such as ammonia and triethylamine may be used in combination when stabilizing the polyacetal.

In this embodiment, the amount of the quaternary ammonium compound (C) used is preferably 0 in terms of the amount n ′ of nitrogen derived from the quaternary ammonium compound (C) represented by the following formula (2 ′). 0.5 mass ppb to 500 mass ppm, more preferably 0.05 to 50 mass ppm.
n ′ = P ′ × 14 / Q ′ (2 ′)
(Wherein P ′ represents an amount (mass ppb or ppm) of the quaternary ammonium compound (C) relative to the total mass of the polyacetal and the quaternary ammonium compound (C), 14 is the atomic weight of nitrogen, and Q 'Represents the molecular weight of the quaternary ammonium compound (C).)
When the usage amount n ′ of the quaternary ammonium compound (C) is 0.5 mass ppb or more, the decomposition rate of the unstable terminal portion of the polyacetal by the combined use of the quaternary ammonium compound (B) is improved. Moreover, even if it is 500 mass ppm or less, the color tone of a polyacetal is not impaired after stabilization.
Here, the amount of the quaternary ammonium compound (C) used is defined in terms of nitrogen because the number of moles of the quaternary ammonium compound (C) relative to the polyacetal varies greatly depending on the molecular weight of the quaternary ammonium compound (C). This is to avoid that.

Next, materials that can be used when producing polyacetal in the present embodiment will be described.
<Trioxane>
Trioxane is a cyclic trimer of formaldehyde, and is generally obtained by reacting a formalin aqueous solution in the presence of an acidic catalyst.
Since this trioxane may contain impurities having chain transfer action such as water, methanol, formic acid, methyl formate, etc., as a pre-stage of the polymerization reaction step, for example, these impurities can be removed by distillation or the like. Removal and purification is preferred.
In that case, the total amount of impurities having the chain transfer action is preferably 1 × 10 ⁻³ mol or less, more preferably 0.5 × 10 ⁻³ mol or less, relative to 1 mol of trioxane.
By reducing the amount of the impurities as shown in the above numerical values, the polymerization reaction rate can be sufficiently increased practically, and a polyacetal having excellent thermal stability can be obtained.

<Cyclic ether and / or cyclic formal>
When the polyacetal is a copolymer, a cyclic ether and / or a cyclic formal can be used as a comonomer. These are components copolymerizable with formaldehyde and the trioxane.
Examples of the cyclic ether or the cyclic formal include, but are not limited to, ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, epibromohydrin, styrene oxide, oxatan, and 1,3-dioxolane. , Ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, and the like. From the viewpoint of easy availability, 1,3-dioxolane and 1,4-butanediol formal are preferred. These may be used alone or in combination of two or more.
The addition amount of the cyclic ether and / or the cyclic formal is preferably in the range of 1 × 10 ^{−2 to} 20 × 10 ⁻² mol with respect to 1 mol of the trioxane, from the viewpoint of mechanical strength of the polyacetal copolymer to be obtained. Preferably it is 1 × 10 ⁻² to 15 × 10 ⁻² mol, more preferably 1 × 10 ⁻² to 10 × 10 ⁻² mol, and even more preferably 1 × 10 ^{−2 to} 5 × 10 ⁻² mol. mol.

<Polymerization catalyst>
Examples of the polymerization catalyst used in the (co) polymerization step of polyacetal include boric acid represented by Lewis acid, tin, titanium, phosphorus, arsenic, and antimonide. In particular, from the viewpoint of easy availability, boron trifluoride, boron trifluoride hydrate, and a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride are preferable. Specifically, boron trifluoride, boron trifluoride diethyl etherate, and boron trifluoride-di-n-butyl etherate are preferable examples. These may be used alone or in combination of two or more.
The addition amount of the polymerization catalyst is preferably in the range of 0.1 × 10 ^{−5 to} 0.1 × 10 ⁻³ mol, more preferably 0.3 × 10 ^{−5 to} 0.5 × 10, with respect to 1 mol of the trioxane. ^-4 in the range of mol, more preferably 0.5 × 10 ^-5 ~0.4 × 10 ^- in the range of 4 mol.
By setting the addition amount of the polymerization catalyst within the above range, it is possible to stably carry out the polymerization reaction for a long time while reducing the amount of scale generated in the supply section of the polymerization reactor.

<Low molecular weight acetal>
In the polymerization step of the polyacetal used in the present embodiment, a low molecular weight acetal represented by the following general formula (4) can also be used.
_{R- (CH 2 -O) n-} R ··· (4)
(In the general formula (4), R represents any one selected from the group consisting of hydrogen, a branched or linear alkyl group, a branched or linear alkoxy group, and a hydroxyl group. Represents an integer of 1 to 20.)
The low molecular weight acetal functions as a chain transfer agent in the polymerization step, and is an acetal having a molecular weight of 200 or less, preferably 60 to 170. By using the acetal having the above molecular weight, the molecular weight of the target polyacetal can be finally adjusted.
Examples of the low molecular weight acetal represented by the general formula (4) include, but are not limited to, methylal, methoxymethylal, dimethoxymethylal, trimethoxymethylal and the like. These may be used alone or in combination of two or more.
The addition amount of the low molecular weight acetal represented by the general formula (4) is 0.1 × 10 ^{−4 to} 0.6 × with respect to 1 mol of the trioxane from the viewpoint of controlling the molecular weight of the target polyacetal within a suitable range. The range of 10 ⁻² mol is preferable, the range of 0.1 × 10 ^{−4 to} 0.6 × 10 ⁻³ mol is more preferable, and the range of 0.1 × 10 ^{−4 to} 0.1 × 10 ⁻³ mol is more preferable. Further preferred.

In the polyacetal resin composition of the present embodiment, additives that are used in the conventional polyacetal resin composition, for example, a heat stabilizer, a weather resistance (light) stabilizer, a release agent, as long as the effects of the present embodiment are not impaired. Molding agents and the like may be used alone or in combination.
Examples of the heat stabilizer include an antioxidant, a scavenger for formaldehyde and formic acid, or a combination thereof, and a combination of an antioxidant and a scavenger is preferable.

As the antioxidant, a hindered phenol-based antioxidant is preferable. For example, n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl- 3- (3'-methyl-5-t-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) -propionate 1,6-hexanediol-bis- (3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate), 1,4-butanediol-bis- (3- (3,5- Di-t-butyl-4-hydroxyphenyl) -propionate), triethyleneglycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) Propionate), tetrakis- (methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate methane, 3,9-bis (2- (3- (3-t- Butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl) 2,4,8,10-tetraoxaspiro (5,5) undecane, N, N′-bis-3- ( 3 ', 5'-di-t-butyl-4-hydroxyphenol) pripionylhexamethylenediamine, N, N'-tetramethylenebis-3- (3'-methyl-5'-t-butyl-4- Hydroxyphenol) propionyldiamine, N, N'-bis- (3- (3,5-di-t-butyl-4-hydroxyphenol) propionyl) hydrazine, N-salicyloyl-N'-salicy Denhydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N′-bis (2- (3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy) ethyl ) Oxyamide and the like.
Among these hindered phenolic antioxidants, triethylene glycol bis- (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate), tetrakis- (methylene-3- (3 ′ , 5'-di-t-butyl-4'-hydroxyphenyl) propionate methane is preferred.

  Specific examples of scavengers for formaldehyde and formic acid include (a) compounds and polymers containing formaldehyde-reactive nitrogen, (b) alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylate salts and An alkoxide etc. are mentioned.

(I) Examples of the compound containing formaldehyde-reactive nitrogen include (1) dicyandiamide, (2) amino-substituted triazine, and (3) a co-condensate of amino-substituted triazine and formaldehyde.
(2) Specific examples of amino-substituted triazines include guanamine (2,4-diamino-sym-triazine), melamine (2,4,6-triamino-sym-triazine), N-butylmelamine, and N-phenylmelamine. N, N-diphenylmelamine, N, N-diallylmelamine, N, N ′, N ″ -triphenylmelamine, N-methylolmelamine, N, N′-dimethylolmelamine, N, N ′, N ″ -tri Methylolmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), 2,4-diamino-6-methyl-sym-triazine, 2,4-diamino-6-butyl-sym-triazine, 2, 4-diamino-6-benzyloxy-sym-triazine, 2,4-diamino-6-butoxy-sym-triazine, , 4-diamino-6-cyclohexyl-sym-triazine, 2,4-diamino-6-chloro-sym-triazine, 2,4-diamino-6-mercapto-sym-triazine, 2,4-dioxy-6-amino -Sym-triazine (Amelite), 2-oxy-4,6-diamino-sym-triazine (Ameline), N, N ', N'-tetracyanoethylbenzoguanamine and the like. (3) Specific examples of the co-condensate of amino-substituted triazine and formaldehyde include melamine-formaldehyde polycondensate. Among these, dicyandiamide, melamine and melamine-formaldehyde polycondensate are preferable.

(A) Polymers having formaldehyde-reactive nitrogen groups include, for example, (1) polyamide resin, (2) acrylamide and derivatives thereof, or acrylamide and derivatives thereof and other vinyl monomers in the presence of metal alcoholates. (3) Polymers obtained by polymerizing acrylamide and its derivatives or acrylamide and its derivatives and other vinyl monomers in the presence of radical polymerization, (4) amines, amides, ureas, urethanes, etc. Examples thereof include a polymer containing a nitrogen group.
Specifically, as the polyamide resin of (1), nylon 4-6, nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 12, etc. and copolymers thereof, nylon 6/6 -6, nylon 6 / 6-6 / 6-10, nylon 6 / 6-12 and the like. (2) As a polymer obtained by polymerizing acrylamide and its derivatives or acrylamide and its derivatives and other vinyl monomers in the presence of metal alcoholate, specifically, poly-β-alanine copolymer and the like can be mentioned. It is done. These polymers can be produced by the methods described in JP-B-6-12259, JP-B-5-87096, JP-B-5-47568 and JP-A-3-234729. (3) Polymers obtained by polymerizing acrylamide and derivatives thereof or acrylamide and derivatives thereof with other vinyl monomers in the presence of radical polymerization can be produced by the method described in JP-A-3-28260. .

  (B) Alkali metal or alkaline earth metal hydroxide, inorganic acid salt, carboxylate and alkoxide, specifically, hydroxide such as sodium, potassium, magnesium, calcium or barium, carbonic acid of the metal Examples include salts, phosphates, silicates, borates, and carboxylates. The carboxylic acid of the carboxylate is a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms, and these carboxylic acids may be substituted with a hydroxyl group. Examples of saturated aliphatic carboxylic acids include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, and celloplastic acid. Examples of the unsaturated aliphatic carboxylic acid include undecylenic acid, oleic acid, elaidic acid, celetic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, propiolic acid, stearic acid and the like. Examples of the alkoxide include methoxide and ethoxide of the above metals.

Examples of the weathering (light) stabilizer include (i) benzotriazole-based materials, (b) oxalic acid anilide-based materials, and (c) hindered amine-based materials.
(I) Specific examples of the benzotriazole-based substance include 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- [2′-hydroxy-3,5-di-t-butyl- Phenyl) benzotriazole, 2- [2′-hydroxy-3,5-di-isoamyl-phenyl) benzotriazole, 2- [2′-hydroxy-3,5-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole and the like, preferably 2- [2'-hydroxy-3,5-bis- (α, α-dimethyl) Benzyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3,5-di-t-butyl-phenyl) benzotriazole.
(B) Specific examples of oxalic acid anilide substances include 2-ethoxy-2'-ethyl oxalic acid bisanilide and 2-ethoxy-5-t-butyl-2'-ethyl oxalic acid bisanilide. 2-ethoxy-3'-dodecyl oxalic acid bisanilide and the like. These substances may be used alone or in combination of two or more.
(C) Specific examples of hindered amine substances include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy. -2,2,6,6-tetramethylpiperidine, 4- (phenylacetoxy) -2,2,6,6-tetramethylpiperidine 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4- Methoxy-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4- Benzyloxy-2,2,6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4- (d Rucarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4- (cyclohexylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6 6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidine) -carbonate, bis (2,2,6,6-tetramethyl-4-piperidyl) -oxalate, bis (2, 2,6,6-tetramethyl-4-piperidyl) -malonate, bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, bis (2,2,6,6-tetramethyl-4 -Piperidyl) -adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) -terephthalate, 1,2-bis (2,2,6,6-tetramethyl) Ru-4-piperidyloxy) -ethane, α, α'-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6,6-tetramethyl) -4-piperidyl) tolylene-2,4-dicarbamate, bis (2,2,6,6-tetramethyl-4-piperidyl) -hexamethylene-1,6-dicarbamate, tris (2,2,6, 6-tetramethyl-4-piperidyl) -benzene-1,3,5-tricarboxylate, tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,4-tricarboxy Examples thereof include bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate. The hindered amine materials may be used alone or in combination of two or more.
Moreover, the combination of the said benzotriazole type material, an oxalic acid anilide type material, and a hindered amine type material is more preferable.

Examples of the release agent include alcohol and esters of alcohol and fatty acid, esters of alcohol and dicarboxylic acid, and silicone oil.
Specific examples of the alcohol include monohydric alcohols and polyhydric alcohols. Examples of monohydric alcohols include octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, Myristyl alcohol, bentadecyl alcohol, cetyl alcohol, hebutadecyl alcohol, stearyl alcohol, oleyl alcohol, nonadecyl alcohol, eicosyl alcohol, pehenyl alcohol, ceryl alcohol, melyl alcohol, 2-hexyldecanol, 2-octyldodecanol, Examples include 2-decyltetradecanol and uniline alcohol. The polyhydric alcohol is a polyhydric alcohol containing 2 to 6 carbon atoms, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol dipropylene glycol, butanediol, pentanediol, hexanediol, glycerin, Examples include diglycerin, triglycerin, threitol, erythritol, pentaerythritol, arabitol, ribitol, xylitol, sorbite, sorbitan, sorbitol, mannitol and the like.
The ester of alcohol and fatty acid is derived from a fatty acid compound, preferably a fatty acid selected from palmitic acid, stearic acid, behenic acid, and montanic acid and a polyhydric alcohol selected from glycerin, pentaerythritol, sorbitan, and sorbitol. Fatty acid esters. The hydroxyl group of these fatty acid ester compounds may or may not exist, and does not limit the fatty acid ester compound. For example, it may be a monoester, a diester, or a triester. Further, the hydroxyl group may be blocked with boric acid or the like.
Specific examples of preferred fatty acid esters include glycerin monopalmitate, glycerin dipalmitate, glycerin tripalmitate, glycerin monostearate, glycerin distearate, glycerin tristearate, glycerin monobehenate, glycerin dibehenate, Glycerol tribehenate, glycerin monomontanate, glycerin dimontanate, glycerin trimontanate, pentaerythritol monopalmitate, pentaerythritol dipalmitate, pentaerythritol tripalmitate, pentaerythritol tetrapalmitate, pentaerythritol monostearate , Pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate Pentaerythritol monobehenate, pentaerythritol dibehenate, pentaerythritol tribehenate, pentaerythritol tetrabehenate, pentaerythritol monomontanate, pentaerythritol dimontanate, pentaerythritol trimontanate, pentaerythritol tetramontanate, Sorbitan monopalmitate, sorbitan dipalmitate, sorbitan tripalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monobehenate, sorbitan dibehenate, sorbitan tribehenate, sorbitan monomontanate , Sorbitan dimontanate, sorbitan trimontanate, sorbitol monopalmitate, sorbitol zippa Mitate, sorbitol tripalmitate, sorbitol monostearate, sorbitol distearate, sorbitol tristearate, sorbitol monobehenate, sorbitol dibehenate, sorbitol tribehenate sorbitol monomontanate, sorbitol dimontanate, sorbitol trimonta And the like.
Moreover, boric acid ester of glycerol mono fatty acid ester is also mentioned as the aliphatic ester compound whose hydroxyl group is blocked with boric acid or the like. Esters of alcohol and dicarboxylic acid are alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, n-amyl alcohol, 2-pentanol, n-heptyl alcohol, and n-octyl. Saturated / unsaturated alcohols such as alcohol, n-nonyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and behenyl alcohol, and dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, Examples thereof include monoesters and diesters with suberic acid, azelaic acid, sebacic acid, undecanoic acid, brassic acid, maleic acid, fumaric acid, glutaconic acid and the like.

  Hereinafter, although a specific Example and a comparative example with this are given and demonstrated about this embodiment, this invention is not limited to a following example.

<Quantitative determination of formaldehyde, acetaldehyde and acrolein>
1. In the case of pellets (before heating and melting) 20.00 g of polyacetal resin composition pellets were placed in a 10 L Tedlar (registered trademark) bag having a valve and sealed, and nitrogen substitution was sufficiently performed. Thereafter, after exhausting all the nitrogen inside, 5.00 L of nitrogen was sealed in the Tedlar (registered trademark) bag. Two of these were prepared.

  Thereafter, the Tedlar (registered trademark) bag is put in an oven having two sampling ports communicating with the outside at the upper part of the inside, and the Tedlar (registered trademark) bag is connected to the sampling port and then left at 90 ° C. for 2 hours. did.

Thereafter, a DNPH (2,4-dinitrophenylhydrazine) cartridge is connected to the outside of the sampling port connected to one Tedlar (registered trademark) bag, the valve of the Tedlar (registered trademark) bag is opened, and the polyacetal resin composition is used. The generated gas 4.00 L was passed through a DNPH cartridge.
5 mL of acetonitrile was passed through the DNPH cartridge at a constant rate, and formaldehyde and acetaldehyde were collected in a 10 mL volumetric flask.
Then, it was made up to 10 mL with water and mixed well.
This mixed solution is dispensed into a vial, HPLC using Shimadzu Corporation, DNPH standard solution as standard solution, water / acetonitrile (52/48) as separation solution, flow rate of 1 mL / min, column temperature of 40 The amount of formaldehyde and acetaldehyde generated per mass of the polyacetal resin composition pellets was measured in ppm by quantification at ° C.
The upper limit of measurement is 15 ppm or less. D. (Not measurable), and below 0.01 ppm, N.I. D. It was.

Connect a CNET (O- (4-cyano-2-ethoxybenzyl) hydroxylamine) cartridge to the outside of the sampling port connected to the remaining one Tedlar® bag, and connect the valve of the Tedlar® bag. Then, 4.00 L of gas generated from the polyacetal resin composition was passed through the CNET cartridge.
5 mL of acetonitrile was passed through the CNET cartridge at a constant rate, and acrolein was collected in a 10 mL volumetric flask.
Then, it was made up to 10 mL with water and mixed well.
This mixed solution is dispensed into vials, using Shimadzu HPLC, using CNET standard solution as the standard solution, water / acetonitrile (40/60) as the separation solution, flow rate of 1 mL / min, column temperature of 40. The amount of acrolein generated per mass of the polyacetal resin composition pellets was measured by ppb after quantification at ° C.
The upper limit of measurement is 30 ppb or less, but those exceeding 20 ppb are O.D. D. It was.

2. In the case of a molded piece (after heating and melting) From a polyacetal resin composition pellet using a Toshiba IS-100GN injection molding machine, a cylinder temperature of 200 ° C., an injection pressure of 60 MPa, an injection time of 15 seconds, a cooling time of 20 seconds, The resin composition was heated and melted at a mold temperature of 80 ° C. to prepare a flat molded piece having dimensions of 130 mm × 110 mm × 3 mm.
After being left for 24 hours in a temperature-controlled room maintained at 23 ° C. and 50% humidity, it was placed in an aluminum bag and packed. On the 14th day after molding, the molded piece was put in a 10 L Tedlar (registered trademark) bag having a valve and sealed, and nitrogen substitution was sufficiently performed. Thereafter, after exhausting all the nitrogen inside, 5.00 L of nitrogen was sealed in a Tedlar (registered trademark) bag. Two of these were prepared.
Thereafter, a Tedlar (registered trademark) bag was placed in an oven having a sampling port penetrating the outside at the upper part of the inside, and the Tedlar (registered trademark) bag was connected to the sampling port and left at 80 ° C. for 2 hours.
Thereafter, formaldehyde, acetaldehyde and acrolein were quantified in the same manner as in the case of pellets.

<Tone characteristics>
Using a IS-100GN injection molding machine manufactured by Toshiba Corporation, from a polyacetal resin composition pellet, cylinder temperature 200 ° C., injection pressure 60 MPa, injection time 15 seconds, cooling time 20 seconds, mold temperature 80 ° C., dimensions A flat test piece of 130 mm × 110 mm × 3 mm was produced.
Two test pieces were stacked on this test piece using a Minolta handy color tester (CR-200), and the yellowness (b value) was measured with a D65 light source.
If the b value was −0.8 or less, the result was generally good, and if the b value was −1.6 or less, it was determined to be good.

<Method for producing crude polyacetal>
Two-axis paddle type continuous polymerization reactor with jacket through which heat medium can pass (made by Kurimoto Steel Works, diameter 2B (2 inches), L (distance from the raw material supply port to the discharge port of the polymerization reactor) / D ( The inner diameter of the polymerization reactor) = 14.8) was adjusted to 80.degree.
An organic solvent mixed solution (I) having an organic solvent having a mass ratio of 9/1 of cyclohexane / heptane and Irganox 1010 as an antioxidant in an organic solvent: antioxidant = 980: 1 ratio was prepared. .
Subsequently, boron trifluoride-di-n-butyl etherate is 0.19 g / hr as a polymerization catalyst, methylal is 2.66 g / hr as a low molecular weight acetal, and the organic solvent mixture (I) is 6.50 g / hr. 1,3-dioxolane as a cyclic ether and / or cyclic formal was continuously mixed at 120.9 g / hr at a temperature of 45 ° C. and a mixing time of 2 minutes to obtain a pre-mixed liquid (I).
The pre-mixed liquid (I) was continuously supplied to the polymerization reactor by piping at 130.25 g / hr, and trioxane was continuously supplied to the polymerization reactor by piping at 3500 g / hr. The crude polyacetal copolymer (A-1) was obtained.
This crude polyacetal copolymer (A-1) was put into a 0.1% by mass aqueous solution of triethylamine to deactivate the catalyst. Then, after filtration and washing, it was dried at 120 ° C. to obtain a crude polyacetal copolymer (A-2).

<Production of Quaternary Ammonium Compound (B) Represented by Formula (1)>
[Production Example 1]
14.1 g of 2- (2-hydroxyethoxy) ethyl acetate, 5.6 g of trimethylamine, 15.0 g of methanol, and 0.1 g of water are introduced into a pressure-resistant container having an inner volume of 60 ml that can be sealed, and stirred with a shaker. The mixture was heated to 120 ° C. Then, after reacting for 6 hours, the contents were obtained by cooling. As a result of analyzing the contents, 2- (2-hydroxyethoxy) ethyl-N, N, N-trimethylethane-1-ammonium acetate was obtained with a yield of 95%.
After adding 15 g of water to 30 g of this solution, the solution is concentrated to 30 g with an evaporator at 80 ° C., and water is added to make 60 g. Concentrate again to 30 g, then add water to 60 g. This operation was repeated 10 times and concentrated to 15 g, and then water was added to make 80 g. This liquid was designated as B-1.
The structural formulas (R1, R2 and X) of the quaternary ammonium compound (B) in the B-1 solution confirmed by NMR are as shown in Table 1, and the concentration thereof was about 20% by mass.

[Production Example 2]
The same procedure as in Production Example 1 was carried out except that 18.2 g of 2- (2- (2-hydroxyethoxy) ethoxy) ethyl acetate was used instead of 14.1 g of 2- (2-hydroxyethoxy) ethyl acetate. This liquid was designated as B-2.
The structural formula (R1, R2, and X) of the quaternary ammonium compound (B) in the B-2 liquid confirmed by NMR is as shown in Table 1, and the concentration was about 22% by mass.
[Production Example 3]
The same procedure as in Production Example 1 was carried out except that 7.8 g of triethylamine was used instead of 5.6 g of trimethylamine and 11.4 g of 2- (2-hydroxyethoxy) ethyl acetate was used. This liquid was designated as B-3.
The structural formula (R1, R2 and X) of the quaternary ammonium compound (B) in the B-3 solution confirmed by NMR is as shown in Table 1, and the concentration was about 20% by mass.
[Production Example 4]
Instead of 5.6 g of trimethylamine, 7.8 g of triethylamine was used, and 14.8 g of 2- (2- (2-hydroxyethoxy) ethoxy) ethyl acetate was used instead of 2- (2-hydroxyethoxy) ethyl acetate. Otherwise, the same procedure as in Production Example 1 was performed. This liquid was designated as B-4.
The structural formulas (R1, R2 and X) of the quaternary ammonium compound (B) in the B-4 liquid confirmed by NMR are as shown in Table 1, and the concentration was about 21% by mass.
[Production Example 5]
Similar to Production Example 1 except that 9.4 g of 2- [2- (dimethylamino) ethoxy] ethanol was used instead of 5.6 g of trimethylamine, and 10.5 g of 2- (2-hydroxyethoxy) ethyl acetate was used. Implemented. This liquid was designated as B-5.
The structural formulas (R1, R2 and X) of the quaternary ammonium compound (B) in the B-5 solution confirmed by NMR are as shown in Table 1, and the concentration was about 20% by mass.

[Production Example 6]
A 10 ml microwave reaction tube was charged with 5.0 g of trimethylamine and 2.63 g of 2- (2-chloroethoxy) ethanol and stirred at 150 ° C. for 1 hour while irradiating with microwaves. After completion of the reaction, the reaction solution was dried under reduced pressure to obtain powder crystals. As a result of analyzing the reaction solution after completion of the reaction by HPLC, it was confirmed that the reaction rate was 100%. After dichloroethane was added to the obtained powder crystals and stirred, the crystals were filtered. This operation was repeated three times and dried under reduced pressure to obtain 2.58 g of powder crystals.
To this powder, 5.62 g of a 1 kg ethanol solution in which 100 g of sodium hydroxide at 40 ° C. was dissolved was added, sodium chloride was filtered off, and the filtrate was collected. After adding 6.46g of formic acid aqueous solution consisting of formic acid / water = 10/90 (mass ratio) to this filtrate, it was concentrated to 5g with an evaporator, and 10g of water was added.
Concentration and addition of 10 g of water were repeated 3 times, and the final weight of 15 g was designated as B-6.
The structural formula (R1, R2 and X) of the quaternary ammonium compound (B) in the B-6 liquid confirmed by NMR is as shown in Table 1, and its concentration was about 17% by mass.

[Production Example 7]
4.5 g of trimethylamine was carried out in the same manner as in Production Example 6 except that 3.21 g of 2- [2- (2-chloroethoxy) ethoxy] ethanol was used instead of 2- (2-chloroethoxy) ethanol. 3.10 g of powder crystals were obtained.
This powder was filtered with sodium chloride and concentrated in the same manner as in Production Example 6 using 5.44 g of the sodium hydroxide ethanol solution used in Production Example 6 and 6.26 g of formic acid aqueous solution. This was designated as B-7.
The structural formulas (R1, R2 and X) of the quaternary ammonium compound (B) in the B-7 liquid confirmed by NMR are as shown in Table 1, and the concentration thereof was about 20% by mass.
[Production Example 8]
The same procedure as in Production Example 6 was carried out except that 5.8 g of triethylamine and 1.79 g of 2- (2-chloroethoxy) ethanol were used instead of trimethylamine to obtain 1.76 g of powder crystals.
Using 3.11 g of the sodium hydroxide ethanol solution used in Production Example 6 and 3.58 g of formic acid aqueous solution, this powder was filtered and concentrated with sodium chloride in the same manner as in Production Example 6 to a final 15 g. This was designated B-8.
The structural formula (R1, R2 and X) of the quaternary ammonium compound (B) in the B-8 liquid confirmed by NMR is as shown in Table 1, and its concentration was about 12% by mass.
[Production Example 9]
Similar to Production Example 6 except that 5.4 g of triethylamine was used instead of trimethylamine and 2.25 g of 2- [2- (2-chloroethoxy) ethoxy] ethanol was used instead of 2- (2-chloroethoxy) ethanol To obtain 2.18 g of powder crystals.
Using 3.24 g of the sodium hydroxide ethanol solution used in Production Example 6 and 3.72 g of formic acid aqueous solution, the sodium chloride was filtered off and concentrated in the same manner as in Production Example 6, resulting in a final 15 g. This was designated B-9.
The structural formula (R1, R2 and X) of the quaternary ammonium compound (B) in the B-9 liquid confirmed by NMR is as shown in Table 1, and the concentration was about 14% by mass.
[Production Example 10]
Production Example 6 except that 4.0 g of trimethylamine and 3.60 g of 2- [2- [2- (2-chloroethoxy) ethoxy] ethoxy] ethanol were used instead of 2- (2-chloroethoxy) ethanol In the same manner, 3.41 g of powder crystals were obtained.
Using 5.02 g of the sodium hydroxide ethanol solution used in Production Example 6 and 5.77 g of formic acid aqueous solution to this powder, sodium chloride was filtered and concentrated in the same manner as in Production Example 6 to finally obtain 15 g. This was designated B-10.
The structural formula (R1, R2, and X) of the quaternary ammonium compound (B) in the B-10 solution confirmed by NMR is as shown in Table 1, and the concentration was about 22% by mass.
[Production Example 11]
Except for using 5.0 g of triethylamine instead of trimethylamine and 2.63 g of 2- [2- [2- (2-chloroethoxy) ethoxy] ethoxy] ethanol instead of 2- (2-chloroethoxy) ethanol, In the same manner as in Production Example 6, 2.50 g of powder crystals were obtained.
Using this powder 3.19 g of sodium hydroxide ethanol solution used in Production Example 6 and 3.67 g of aqueous formic acid solution, sodium chloride was filtered and concentrated in the same manner as in Production Example 6, resulting in a final 15 g. This was designated B-11.
The structural formula (R1, R2 and X) of the quaternary ammonium compound (B) in the B-11 liquid confirmed by NMR is as shown in Table 1, and the concentration was about 16% by mass.

<The quaternary ammonium compound (C) represented by Formula (3)>
C-1: Choline acetate (manufactured by Aldrich)
C-2: Choline hydroxide (manufactured by Tama Chemical Industries)
It was used.

[Examples 1-44]
The crude polyacetal copolymer (A-1) was put into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst. Thereafter, the solution of the quaternary ammonium compound (B) prepared in each production example is filtered and washed, and the nitrogen concentration n is as shown in Table 2 with respect to 100 parts by mass of the crude polyacetal copolymer (A-1). Was added, mixed uniformly, and dried at 120 ° C.
0,2'-methylenebis- (4-methyl-t-butylphenol) was added as an antioxidant to 100 parts by mass of the resulting crude polyacetal copolymer composition containing the quaternary ammonium compound (B). .3 parts by mass was added and fed to a twin screw extruder with a vent.
If necessary, water and / or triethylamine is added to the molten crude polyacetal copolymer composition in the extruder, and the crude polyacetal copolymer is obtained at a set temperature of the extruder of 200 ° C. and a residence time of 5 minutes in the extruder. The unstable terminal part of was decomposed. The polyacetal copolymer composition in which the unstable terminal portion was decomposed was devolatilized under the condition of a vent vacuum degree of 20 Torr, extruded as a strand from the extruder die portion, and pelletized.
Type of quaternary ammonium compound (B) used, and amount (content) of quaternary ammonium compound (B) used relative to the total mass of polyacetal copolymer and quaternary ammonium compound (B) (fourth Nitrogen concentration derived from quaternary ammonium compound (B), water added to extruder, addition amount of triethylamine to 100 parts by mass of crude polyacetal copolymer composition, formaldehyde (FA), acetaldehyde (AA) and acrolein (AL) Table 2 summarizes the amount and color tone.

[Examples 45 to 50]
The crude polyacetal copolymer (A-1) was put into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst. Then, the solution of the quaternary ammonium compound (B) produced by each manufacture example with respect to 100 mass parts of crude polyacetal copolymers (A-1) which filtered and wash | cleaned, and the above-mentioned quaternary ammonium compound ( C) was added in such an amount that the nitrogen concentrations n and n ′ derived therefrom were as shown in Table 2, and the mixture was uniformly mixed and then dried at 120 ° C.
With respect to 100 parts by mass of the crude polyacetal copolymer composition containing the obtained quaternary ammonium compounds (B) and (C), 2,2′-methylenebis- (4-methyl-t-) as an antioxidant is used. Butylphenol) was added in an amount of 0.3 parts by mass, and the mixture was supplied to a twin screw extruder with a vent.
If necessary, water and / or triethylamine is added to the molten crude polyacetal copolymer composition in the extruder, and the crude polyacetal copolymer is obtained at a set temperature of the extruder of 200 ° C. and a residence time of 5 minutes in the extruder. The unstable terminal part of was decomposed. The polyacetal copolymer composition in which the unstable terminal portion was decomposed was devolatilized under the condition of a vent vacuum of 20 Torr, extruded as a strand from the extruder die, and pelletized.
The kind of the quaternary ammonium compound (B) and the quaternary ammonium compound (C) used and the amount of each quaternary ammonium compound relative to the total mass of the polyacetal copolymer and the quaternary ammonium compounds (B) and (C). Use amount (content) (nitrogen concentration n, n ′), water added to the extruder, addition amount of triethylamine to 100 parts by mass of the crude polyacetal copolymer composition, formaldehyde (FA), acetaldehyde (AA) and acrolein ( The amount of AL) and the color tone are summarized in Table 3.

[Comparative Examples 1-9]
In Examples 1-44, it implemented like Example 1-44 except having used the quaternary ammonium compound (C) instead of the quaternary ammonium compound (B). The results are summarized in Table 4.

[Examples 51 to 65]
To 100 parts by mass of the crude polyacetal copolymer (A-2), 0.3 part by mass of 2,2′-methylenebis- (4-methyl-t-butylphenol) is added as an antioxidant, and a biaxial shaft with a vent is added. It supplied to the screw type extruder.
A quaternary ammonium compound (B) is added to the molten crude polyacetal copolymer composition in the extruder together with water and / or triethylamine in an amount such that the nitrogen concentration n is as shown in Table 2. The unstable terminal portion of the crude polyacetal copolymer was decomposed at a set temperature of 200 ° C. and a residence time of 5 minutes in the extruder. The polyacetal copolymer composition in which the unstable terminal portion was decomposed was devolatilized under the condition of a vent vacuum of 20 Torr, extruded as a strand from the extruder die, and pelletized.
Kind of quaternary ammonium compound (B) used and amount of polyacetal copolymer and quaternary ammonium compound used relative to the total mass (nitrogen concentration n), water added to extruder, crude polyacetal copolymer composition of triethylamine Table 3 summarizes the addition amount, formaldehyde (FA), acetaldehyde (AA) and acrolein (AL) amount and color tone with respect to 100 parts by mass of the product.

[Comparative Examples 10-15]
In Examples 51-65, it implemented like Example 51-65 except having used the quaternary ammonium compound (C) instead of the quaternary ammonium compound (B). The results are summarized in Table 4.

[Comparative Example 17]
It implemented like Example 1-44 except having used the tetrakis [(2-hydroxyethyl) trimethylammonium] salt (D-1) of ethylenediaminetetraacetic acid instead of the quaternary ammonium compound (B). The results are summarized in Table 4.

[Comparative Example 18]
To 100 parts by mass of the crude polyacetal copolymer (A-2), 0.3 part by mass of 2,2′-methylenebis- (4-methyl-t-butylphenol) is added as an antioxidant, and a biaxial shaft with a vent is added. It supplied to the screw type extruder.
To the molten crude polyacetal copolymer composition in the extruder, together with water and / or triethylamine, (2-hydroxyethyl) trimethylammonium salt of polyacrylic acid (equimolar salt of acrylic acid unit, polyacrylic acid Number average molecular weight = 7000) (D-2) is added in an amount such that the nitrogen concentration is as shown in Table 2, and the unstable end is decomposed at a preset temperature of the extruder of 200 ° C. and a residence time of 5 minutes in the extruder. It was. The polyacetal copolymer composition in which the unstable terminal portion was decomposed was devolatilized under the condition of a vent vacuum of 20 Torr, extruded as a strand from the extruder die portion, and pelletized. The evaluation results of this pellet are shown in Table 4.

As shown in Tables 2 and 3, in Examples 1 to 65, it is possible to obtain a polyacetal resin composition in which generation of formaldehyde, acetaldehyde and acrolein is suppressed both before and after heat-melt processing (pellets and molded pieces), The thing which was excellent also in the color tone was obtained.
In Examples 37 to 44 and 50, although the b value was slightly high, polyacetal resin compositions in which the generation of formaldehyde, acetaldehyde and acrolein was suppressed were obtained. In addition, the reason why the b value was slightly increased in these cases is that the quaternary ammonium compound (B) is used in the quaternary ammonium compound (B) because R2 is long, so It is presumed that it was likely to remain, and this was colored during heating and melting.
As shown in Table 4, in Comparative Examples 1 to 8 and 10 to 15 using only the quaternary ammonium compound (C) without using the quaternary ammonium compound (B), generation of formaldehyde, acetaldehyde and acrolein Although it was possible to obtain polyacetal resin composition pellets that were suppressed, the generation of formaldehyde, acetaldehyde, and acrolein during heating and melting could not be sufficiently suppressed.
In Comparative Example 9 in which no quaternary ammonium compound was used, it was not possible to obtain polyacetal resin composition pellets in which the generation of formaldehyde, acetaldehyde and acrolein was suppressed.
Instead of the quaternary ammonium compound (B), a quaternary ammonium compound (D-1) or a quaternary ammonium compound (B) containing a nitrogen atom in the group corresponding to X in the formula (1) In addition, in Comparative Examples 17 and 18 using (D-2) containing a polycarboxylic acid in the group corresponding to X in Formula (1), the generation of formaldehyde, acetaldehyde and acrolein cannot be sufficiently suppressed. It was.

Claims (5)

Polyacetal (A),
A quaternary ammonium compound (B) represented by the following formula (1) (excluding those constituting a complex with silicate)
A polyacetal resin composition comprising:
[(R1) _m (R2) _4-m N ⁺ ] _n X ⁿ⁻ (1)
(In Formula (1), R1 represents a C1-C2 unsubstituted alkyl group each independently.
R2 independently represents a group represented by the following formula having 2 to 8 carbon atoms and 2 to 4 oxygen atoms.
-(RO) k-H (wherein R represents a substituted or unsubstituted alkylene group having 1 to 2 carbon atoms, and k represents a natural number of 2 to 4).
m and n represent an integer of 1 to 3.
X represents an acid residue of at least one monocarboxylic acid selected from the group consisting of formic acid, acetic acid and propionic acid . ) The polyacetal resin composition according to claim 1, wherein the nitrogen concentration n derived from the quaternary ammonium compound (B) represented by the following formula (2) is 0.1 ppb or more and 30 ppm or less on a mass basis.
n = P × 14 / Q (2)
(Wherein P represents the amount of quaternary ammonium compound (B) relative to the total amount of polyacetal and quaternary ammonium compound (B) (mass ppb or ppm), 14 is the atomic weight of nitrogen, and Q is Represents the molecular weight of the quaternary ammonium compound (B).) The polyacetal resin composition of Claim 1 or 2 whose carbon number of R2 in Formula (1) is 2-6. In the presence of a polyacetal having a thermally unstable terminal portion, a quaternary ammonium compound (B) represented by the following formula (1) (excluding those constituting a complex with silicate): The manufacturing method of the stabilization polyacetal including the process to heat-process.
[(R1) _m (R2) _4-m N ⁺ ] _n X ⁿ⁻ (1)
(In the formula (1),
R1 represents each independently an unsubstituted alkyl group having 1 to 2 carbon atoms.
R2 independently represents a group represented by the following formula having 2 to 8 carbon atoms and 2 to 4 oxygen atoms.
-(RO) k-H (wherein R represents a substituted or unsubstituted alkylene group having 1 to 2 carbon atoms, and k represents a natural number of 2 to 4).
m and n represent an integer of 1 to 3.
X represents an acid residue of at least one monocarboxylic acid selected from the group consisting of formic acid, acetic acid and propionic acid . ) Said heat treatment, quaternary ammonium compound represented by the above formula (1), and carried out in the presence of a quaternary ammonium compound represented by the following formula (3) (C), according to claim 4 the method of.
[R3R4R5R6N ⁺ ] _l Y ^l− (3)
(In Formula (3), R3, R4, R5, and R6 are each independently an unsubstituted alkyl group or substituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; and 1 to 30 carbon atoms. Or an aralkyl group in which the substituted alkyl group is substituted with at least one aryl group having 6 to 20 carbon atoms; or the aryl group having 6 to 20 carbon atoms is at least one non-alkyl group having 1 to 30 carbon atoms Represents a substituted alkyl group or an alkylaryl group substituted with a substituted alkyl group, and the unsubstituted alkyl group and the substituted alkyl group are linear, branched, or cyclic, and the substituent of the substituted alkyl group is a halogen, a hydroxyl group An aldehyde group, a carboxyl group, an amino group, or an amide group, and an unsubstituted alkyl group, an aryl group, an aralkyl group, and an alkylaryl group have a hydrogen atom as a halogen atom. May be substituted.
l represents an integer of 1 to 3.
Y represents a hydroxyl group or an acid residue of a compound selected from the group consisting of a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid, an oxo acid, an inorganic thioacid, and an organic thioacid having 1 to 20 carbon atoms. )