Modified polyacetal resin production method

Abstract

The purpose of the present invention is to provide a new polyacetal resin production method that enables provision of various modified polyacetal resins by facilitating modification of a polyacetal resin. [Solution] Said purpose of the present invention is achieved by a modified polyacetal resin production method comprising at least: (1) a step for producing a crude polyacetal polymer by polymerizing a monomer by using a protonic acid catalyst; and (2) a step for inactivating said protonic acid catalyst and simultaneously causing a reaction between the crude polyacetal polymer and an organic compound having a hydroxy group.

Description

Manufacturing method of modified polyacetal resin

[0001] The present invention relates to a method for producing a modified polyacetal resin.

[0002] A commonly known modification method for introducing specific structural units or functional groups into the main chain or terminals of a polyacetal resin is cationic copolymerization of trioxane as a main monomer with a comonomer copolymerizable therewith. For example, it is known to melt-knead a polyacetal resin and a polymer having an active hydrogen atom or a glycidyl group in the molecule before deactivating the cationic polymerization catalyst (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2005-105103

[0004] In recent years, the versatility of polyacetal resins has expanded, and there is a demand for modified polyacetal resins tailored to specific applications. However, there are limitations on the comonomers that can be copolymerized and the compounds that can react with the terminals, making it difficult to achieve the desired modifications.

[0005] An object of the present invention is to provide a method for producing a polyacetal resin that facilitates the modification of a polyacetal resin and enables the provision of a variety of modified polyacetal resins.

[0006] The present invention has been achieved by the following.

[0007] 1. A method for producing a modified polyacetal resin, comprising at least the steps of: (1) polymerizing a monomer using a protonic acid catalyst to produce a crude polyacetal polymer; and (2) deactivating the protonic acid catalyst and simultaneously reacting the crude polyacetal polymer with an organic compound having a hydroxyl group. 2. The method for producing a modified polyacetal resin according to (1) above, wherein the protonic acid catalyst is selected from a heteropolyacid or a mixture of a heteropolyacid and a salt thereof. 3. The method for producing a modified polyacetal resin according to (1) above, wherein the deactivator that deactivates the protonic acid catalyst is an amine compound, a quaternary ammonium compound, or an alkali metal salt.

[0008] According to the present invention, it is possible to provide a method for producing a polyacetal resin that facilitates the modification of a polyacetal resin and enables the provision of a variety of modified polyacetal resins.

[0009] FIG. 1 is a schematic diagram showing one manufacturing process according to an embodiment of the present invention.

[0010] Specific embodiments of the present invention will be described in detail below. Note that the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0011] The method for producing a modified polyacetal resin of the present invention includes: (1) a step of polymerizing a monomer using a protonic acid catalyst to produce a crude polyacetal polymer; and (2) a step of deactivating the protonic acid catalyst and simultaneously reacting the crude polyacetal polymer with an organic compound having a hydroxyl group.

[0012] <Step (1): Step of Producing a Crude Polyacetal Polymer> Step (1) is a step of producing a crude polyacetal polymer by polymerizing a monomer using a protonic acid catalyst. The "crude polyacetal polymer" of the present invention refers to a polymer in a state in which the monomer has been polymerized but the catalyst has not yet been deactivated, and refers to a polymer with a polymerization rate of 60% or more. Preferably, it is a polymer with a polymerization rate of 65% or more. Here, the "polymerization rate" refers to the value expressed as a percentage of the amount of polymer obtained after the polymerization reaction relative to the amount of monomer used.

[0013] <<Monomer>> In the present invention, there are no particular limitations on the monomers that can be used to produce the modified polyacetal resin, but it is preferable to use trioxane as the main monomer. Examples of comonomers include cyclic formals having at least one carbon-carbon bond, such as 1,3-dioxolane, 1,3,6-trioxocane, and 1,4-butanediol formal. Of these, 1,3-dioxolane is preferred from the viewpoint of production.

[0014] Furthermore, as a comonomer, compounds having two or more epoxy groups in the molecule such as butanediol diglycidyl ether, compounds having a glycidyl group such as glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether, compounds having an epoxy group such as 1,3-butadiene diepoxide, 1,4-pentadiene diepoxide, 1,5-hexadiene diepoxide, 1,6-dibutadiene diepoxide, 1,7-octadiene diepoxide, 1,8-nonanediene diepoxide, 1,9-decane diepoxide, 1,10-undecane diepoxide, and 1,11-dodecane diepoxide, and compounds having an alicyclic epoxy group such as 2-(3,4-epoxycyclohexyl)ethyl can also be used. This allows for the production of polyacetal copolymers having a branched or crosslinked structure.

[0015] In the present invention, the comonomer content is preferably in the range of 0.01 to 20 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of trioxane. When the comonomer content is 0.01 part by mass or more per 100 parts by mass of trioxane, polymerization can proceed stably. Furthermore, when the comonomer content is 20 parts by mass or less per 100 parts by mass of trioxane, a decrease in the crystallization rate and the degree of crystallization of the polymer chain can be suppressed.

[0016] <<Protonic Acid Catalyst>> Examples of protonic acid catalysts that can be used in the present invention include heteropolyacids, mixtures of heteropolyacids and their salts, isopolyacids, perfluoroalkanesulfonic acids, and the like.

[0017] Examples of heteropolyacids include phosphomolybdic acid, phosphotungstic acid, phosphomolybdotungstic acid, phosphomolybdovanadic acid, phosphomolybdotungstovanadic acid, phosphotungstovanadic acid, silicotungstic acid, silicomolybdic acid, silicomolybdotungstic acid, silicomolybdotungstovanadic acid, etc. The heteropolyacid is preferably at least one of silicomolybdic acid, silicotungstic acid, phosphomolybdic acid, and phosphotungstic acid. Use of a heteropolyacid can provide good polymerization stability.

[0018] As the salt of heteropolyacid, an alkali metal salt is preferred. Examples of alkali metal salts of heteropolyacid include sodium phosphotungstate, lithium phosphotungstate, and potassium phosphotungstate. Among the alkali metals, sodium is preferred. By using sodium phosphotungstate, good polymerization stability can be obtained.

[0019] The mass mixing ratio of the heteropolyacid and its salt (heteropolyacid salt / heteropolyacid) is preferably not more than 10, and more preferably not more than 5. If the mass mixing ratio exceeds 10, the amount of catalyst used increases, resulting in the excessive production of hydroxyl terminal groups that reduce formaldehyde generation and deteriorate the quality of the polymer, which is undesirable.

[0020] Examples of isopolyacids include isopolytungstic acids such as paratungstic acid and metatungstic acid, isopolymolybdic acids such as paramolybdic acid and metamolybdic acid, metapolyvanadic acids, and isopolyvanadic acids. Among these, isopolytungstic acid is preferred. By using isopolytungstic acid, good polymerization stability can be obtained.

[0021] Examples of perfluoroalkanesulfonic acids include trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, nonafluorobutanesulfonic acid, undecafluoropentanesulfonic acid, tridecafluorohexanesulfonic acid, pentadecafluoroheptanesulfonic acid, and heptadecafluorooctanesulfonic acid. Among these, trifluoromethanesulfonic acid is preferred. By using trifluoromethanesulfonic acid, good polymerization stability can be obtained.

[0022] In the present invention, the amount of the protonic acid catalyst used can be adjusted appropriately depending on the type of protonic acid catalyst to control the polymerization reaction. Generally, the amount of the protonic acid catalyst used is preferably in the range of 0.05 to 100 ppm (hereinafter referred to as mass / mass ppm) relative to the total amount of monomers, and more preferably in the range of 0.1 to 50 ppm. When the amount of the protonic acid catalyst used is 0.05 to 100 ppm relative to the total amount of monomers, polymerization can proceed sufficiently, making it easy to obtain the desired degree of polymerization. On the other hand, when the amount of the protonic acid catalyst used exceeds 100 ppm relative to the total amount of monomers, excessive hydroxyl terminal groups that result in reduced formaldehyde generation are produced, which is undesirable because it reduces the quality of the polymer.

[0023] To carry out the reaction uniformly, it is desirable to use the protonic acid catalyst by diluting it with an inert solvent that does not adversely affect the polymerization and adding it to the main monomer and / or comonomer. Examples of the inert solvent include methyl formate, ethyl formate, methyl acetate, ethyl acetate, butyl acetate, acetone, 2-butanone, methyl isobutyl ketone, etc.

[0024] The protonic acid catalyst is dissolved in the inert solvent preferably at a concentration of 1 to 30% by mass / mass, but is not limited thereto. In addition, a method is preferred in which a predetermined amount of the protonic acid catalyst is premixed with a part or all of one or more of the main monomer, comonomer, molecular weight modifier, etc., and the resulting solution is added to the polymerization system to carry out polymerization.

[0025] <Molecular Weight Regulator> In the production of the crude polyacetal copolymer of the present invention, it is preferable to use a molecular weight regulator in addition to the above components to regulate the molecular weight. As the molecular weight regulator, a chain transfer agent known in cationic polymerization can be used.

[0026] Examples of chain transfer agents include linear formals such as methylal, ethylal, and dibutoxymethane, alcohols such as methanol, ethanol, and ethylene glycol, and water. Among these, methylal, ethylal, and dibutoxymethane are preferred, as they do not form unstable terminals. The amount added is preferably 50 to 2,000 ppm based on the total amount of monomers.

[0027] <<Method for Producing Crude Polyacetal Polymer>> The crude polyacetal polymer of the present invention can be obtained by continuously supplying a mixed liquid containing the above-mentioned trioxane, 1,3-dioxolane, a molecular weight modifier, and a protonic acid catalyst to a polymerization reaction apparatus (continuous twin-screw paddle screw extruder type) having an external jacket for passing a heating or cooling medium therethrough, and polymerizing the mixture for a predetermined period of time.

[0028] <Step (2): Step of deactivating the protonic acid catalyst and simultaneously reacting the crude polyacetal polymer with an organic compound having a hydroxyl group> Step (2) is a step of adding a deactivator to the crude polyacetal polymer obtained in the above-mentioned step (1) to deactivate the remaining protonic acid catalyst and stabilize the unstable terminals of the crude polyacetal polymer, while simultaneously reacting the crude polyacetal polymer with an organic compound having a hydroxyl group. This step makes it possible to modify the crude polyacetal polymer by introducing residues of the organic compound having a hydroxyl group, and also makes it possible to adjust the degree of modification by changing the conditions for adding the deactivator to adjust the amount of deactivation of the protonic acid catalyst.

[0029] Here, "deactivating the protonic acid catalyst and simultaneously reacting the crude polyacetal polymer with an organic compound having hydroxyl groups" refers not only to the case where the deactivator and the organic compound having hydroxyl groups are added to the reaction system simultaneously and reacted with the crude polyacetal polymer, but also to the case where the reaction between the deactivator and the crude polyacetal polymer and the reaction between the organic compound having hydroxyl groups and the crude polyacetal polymer proceed simultaneously in the reaction system, even if the deactivator and the organic compound having hydroxyl groups are not added to the reaction system at the same time. For example, the case where the organic compound having hydroxyl groups is added first and reacted with the crude polyacetal polymer, and then the deactivator is added to the reaction system during the reaction, and the case where the organic compound is added in the reverse order, are also included.

[0030] The method for adding the hydroxyl group-containing organic compound and the deactivator to the crude polyacetal polymer obtained in step (1) can be appropriately selected from known methods such as batchwise and continuous methods.

[0031] <<Deactivator>> The deactivator that can be used in the present invention is not particularly limited. From the viewpoint that the deactivator can be added directly to the crude polyacetal polymer and melt-kneaded under heating to deactivate the protonic acid catalyst and stabilize the unstable terminals of the crude polyacetal polymer, the deactivator preferably contains at least one selected from an amine compound, a compound having a quaternary ammonium group, and a carbonate, hydrogencarbonate, or carboxylate of an alkali metal element or an alkaline earth metal element, or a hydrate thereof. Two or more of these may also be used in combination.

[0032] Examples of amine compounds include primary amine compounds such as methylamine, ethylamine, propylamine, isopropylamine, butylamine, etc.; secondary amine compounds such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, etc.; tertiary amine compounds such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, etc. Examples of compounds with quaternary ammonium group include choline or choline salt, etc. Among these, choline or choline salt is preferred.

[0033] Examples of carbonates, bicarbonates, or carboxylates of alkali metals or alkaline earth metals, or their hydrates, include sodium formate, sodium acetate, potassium carbonate, sodium carbonate, sodium bicarbonate, disodium succinate, sodium laurate, sodium palmitate, sodium stearate, or calcium stearate. Of these, sodium carbonate, sodium bicarbonate, and sodium stearate are preferred. These may be used singly or in combination of two or more.

[0034] The amount of the deactivator to be added is not particularly limited, but is preferably 0.002 to 1.0 milliequivalents per kg of crude polyacetal copolymer. When the amount is within the range of 0.002 to 1.0 milliequivalents, discoloration of the resulting polymer can be suppressed.

[0035] <<Organic Compound Having a Hydroxyl Group>> Examples of organic compounds having a hydroxyl group (hereinafter also referred to as hydroxyl group-containing organic compounds) that can be used in the present invention include organic compounds having an alcoholic hydroxyl group. A single compound may have multiple hydroxyl groups. Examples include alcohols having 1 to 34 carbon atoms, polyalkylene oxides (e.g., ethylene oxide, propylene oxide, etc.) that have terminal hydroxyl groups and a number-average molecular weight of 1,000 or less, and polyethylene glycols (PEGs) (e.g., PEG600, PEG400, PEG300, etc.) that have an average molecular weight of 600 or less.

[0036] The organic compound having a hydroxyl group can be appropriately selected depending on the application of the polyacetal resin, and the degree of modification can also be appropriately selected.

[0037] <<Method for Producing Modified Polyacetal Resin>> The method for producing a modified polyacetal resin of the present invention will be outlined with reference to Figure 1. In Figure 1, A denotes a polymerization apparatus for polymerizing a monomer in "Step (1): a step for producing a crude polyacetal polymer," and B denotes an extruder for reacting the crude polyacetal polymer with an organic compound having a hydroxyl group and simultaneously deactivating the polymerization catalyst in "Step (2): a step for deactivating a protonic acid catalyst and reacting the crude polyacetal polymer with an organic compound having a hydroxyl group." Furthermore, X and Y in Figure 1 indicate positions at which a deactivator is added. Specifically, X denotes the position at which the deactivator is added before entering the extruder (before melt-kneading), and Y denotes the position at which the deactivator is added midway through the extruder.

[0038] Next, the above-mentioned treatment method for "deactivating the protonic acid catalyst" (hereinafter also referred to as "catalyst deactivation treatment") and the step of modifying the crude polyacetal polymer will be described. Specifically, the catalyst deactivation treatment involves adding a deactivator or a solution of the deactivator to the crude polyacetal polymer from position X shown in Figure 1 as shown in the following (A) to (D), and then melt-kneading both the deactivator and the crude polyacetal polymer in extruder B.

[0039] (A) The deactivator is added directly to the crude polyacetal polymer. (B) A solution containing the deactivator is added to the crude polyacetal polymer. (C) The solution containing the deactivator is mixed with pre-prepared polyacetal resin powder, and then added to the crude polyacetal polymer. (D) The deactivator is mixed directly with pre-prepared polyacetal resin powder, and then added to the crude polyacetal polymer.

[0040] Alternatively, as shown in the following (e) to (h), the crude polyacetal polymer may be added from position Y shown in FIG. 1 while being melt-kneaded in extruder B.

[0041] (E) A solution containing a deactivator is added by injection or the like to the melt-kneaded portion midway through extruder B. (F) The deactivator is added as is to the melt-kneaded portion midway through extruder B. (G) A solution containing a deactivator is mixed with a polyacetal resin powder prepared in advance, and the dispersed powder is then added to the melt-kneaded portion midway through extruder B. (H) The deactivator is mixed as is with a polyacetal resin powder prepared in advance, and the dispersed powder is then added to the melt-kneaded portion midway through extruder B.

[0042] The powder of the crude polyacetal polymer or polyacetal resin indicated by (A) to (H) may be mixed with the deactivator using a general mixer such as a horizontal cylindrical type, V-type, ribbon type, paddle type, high-speed flow type, etc. The molten resin discharged from a discharge die (not shown) installed at the discharge portion of the extruder B is cooled and then cut into pellets to form a modified polyacetal resin.

[0043] With regard to the timing of adding the deactivator in the catalyst deactivation treatments (a) to (h), the hydroxyl group-containing organic compound of the present invention can be added simultaneously with or separately from the deactivator.

[0044] When the hydroxyl group-containing organic compound is added simultaneously with the deactivator, the hydroxyl group-containing organic compound and the deactivator can be added to the same position (X or Y) directly or after being mixed with a polyacetal resin powder prepared in advance.

[0045] When the hydroxyl-containing organic compound is added separately from the deactivator, the hydroxyl-containing organic compound, either as is or mixed with a previously prepared polyacetal resin powder, is fed from X into extruder B together with the crude polyacetal polymer for melt-kneading, and the deactivator can be added to the melt-kneading section (not shown) by the methods described in (e) to (h) above. Alternatively, the deactivator can be added from X to the crude polyacetal polymer before melt-kneading by the methods described in (a) to (d) above, and then melt-kneading is performed in extruder B, and the hydroxyl-containing organic compound, either as is or mixed with a previously prepared polyacetal resin powder, can be added to the melt-kneading section (not shown) by Y. Note that when the hydroxyl-containing organic compound is added separately from the deactivator and mixed, it is preferable to add the hydroxyl-containing organic compound before melt-kneading.

[0046] The modification of the present invention occurs specifically in crude polyacetal polymers polymerized using a protonic acid catalyst, and the efficiency of modification is extremely low when a Lewis acid, such as boron trifluoride, is used as a catalyst. The modification of the present invention is specifically possible when a protonic acid catalyst is used.

[0047] Furthermore, in the present invention, the reaction with the organic compound having a hydroxyl group and the catalyst deactivation reaction are competitive reactions, and therefore the progress of the reaction between the crude polyacetal polymer and the organic compound having a hydroxyl group can be adjusted by the deactivation treatment, and the degree of modification can also be adjusted.

[0048] <Other Steps> The present invention may include other steps. For example, the present invention may include a step of adding various additives midway through the extrusion process and melt-kneading the mixture, or a step of adding various additives to pelletized polyacetal resin and then melt-kneading the mixture again.

[0049] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples.

[0050] <Step (1)> In step (1), polymerization was carried out as follows to produce a crude polyacetal polymer. A continuous twin-screw paddle screw extruder was used as the polymerization apparatus A. The polymerization apparatus A was equipped with a jacket (not shown) on the outside of the body for passing a heating or cooling medium. The body was divided into upper and lower parts, and the upper part was openable. Inside the polymerization apparatus A, two rotating shafts equipped with numerous paddles for stirring and propulsion were provided in the longitudinal direction.

[0051] A mixed liquid containing 100 parts by mass of trioxane as a main monomer, 4.3 parts by mass of 1,3-dioxolane as a comonomer, and 1000 ppm of a molecular weight regulator per unit time was continuously supplied to the body portion heated by the jacket, the temperature of which was controlled by passing a medium at 80°C, and a polymerization catalyst was supplied to the mixed liquid.

[0052] The content of the polymerization catalyst is 4 ppm in the case of a combination of phosphotungstic acid and trifluoromethanesulfonic acid, 1 ppm in the case of a combination of phosphotungstic acid and its salt, H ５ PV ２ W １０ O ４０ Copolymerization was carried out by continuously adding 6 ppm of a combination of (HPA) and a salt of phosphotungstic acid, and 30 ppm of boron trifluoride diethyl etherate (relative to the total monomer, unit: ppm by mass) as a solution. The concentration of the polymerization catalyst boron trifluoride diethyl etherate is expressed as boron trifluoride.

[0053] <Step (2)> In step (2), a hydroxyl group-containing organic compound and a deactivator shown in Tables 1 and 2 were added to the flake-like crude polyacetal polymer discharged from the polymerization apparatus A, and the mixture was melt-kneaded in a vented twin-screw extruder with a cylinder temperature of 210°C to obtain pellet-like modified polyacetal resin. The hydroxyl group-containing organic compound and the deactivator were added as follows.

[0054] When the deactivator was added at position X: 2 parts by mass of a polyacetal resin powder was added to 100 parts by mass of the crude polyacetal polymer, and the organic compound having a hydroxyl group and the deactivator shown in Tables 1 and 2 were mixed and added together with the crude polyacetal polymer from position X.

[0055] When the deactivator was added at position Y, an organic compound having a hydroxyl group shown in Tables 1 and 2 was added to 2 parts by mass of polyacetal resin powder relative to 100 parts by mass of crude polyacetal polymer, and the mixture was added together with the crude polyacetal polymer from position X, and then a deactivator shown in Tables 1 and 2 was added from position Y.

[0056] Compounds listed in Tables 1 and 2 [Organic compounds having a hydroxyl group] OH1: docosanol (carbon number: 22) OH2: pentanediol (carbon number: 5) OH3: polyethylene glycol 400 (PEG400)

[0057] [Catalyst] The following catalysts were added in the form of solutions shown in parentheses. PWA: phosphotungstic acid (0.2 wt% methyl formate solution) PWA + salt: an equal mass mixture of phosphotungstic acid and sodium phosphotungstate (0.2 wt% methyl formate solution) HPA + salt: H ５ PV ２ W １０ O ４０ and an equal mass mixture of sodium phosphotungstate (0.2 wt % solution in methyl formate). TFMSA: trifluoromethanesulfonic acid (0.2 wt % solution in cyclohexane). BF ３ : Boron trifluoride diethyl etherate (a cyclohexane solution containing 1.5 wt% boron trifluoride)

[0058] [Quenching agents] The amount added was 10 ppm. Those that were solid at room temperature were added as solids, and those marked "aq." in Tables 1 and 2 were added as aqueous solutions (concentration: 0.5 mg / mL). StNa: sodium stearate Na ２ CO ３ : sodium carbonate, K ２ CO ３: Potassium carbonate, choline, TEA: Triethylamine

[0059] <Modification Evaluation> 0.2 g of the pellet-shaped modified polyacetal resin obtained through steps (1) and (2) was dissolved in 4 ml of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), and 8 ml of methanol was added thereto with stirring to cause reprecipitation. The reprecipitated resin was collected by filtration and dried. The dried polyacetal resin was subjected to the above treatment again, and the resulting resin was used as a sample. 30 mg of the obtained sample was dissolved in deuterated HFIP (0.6 ml), and 1H-NMR (nuclear magnetic resonance) measurement was performed using an AVANCE III 400 (manufactured by Bruker BioSpin) equipped with a Cryo probe at a temperature setting of 318 K and with 128 accumulations. The amount of hydroxyl-containing organic compound introduced was determined from the peak areas of the oxymethylene and oxyethylene groups derived from the polyacetal polymer and the peak area of ​​the methylene group adjacent to the hydroxyl group of the hydroxyl-containing organic compound in the obtained NMR spectrum.

[0060] The amount of hydroxyl group-containing organic compound introduced into each material obtained by melt-kneading 5000 ppm of the hydroxyl group-containing organic compound with the crude polyacetal polymer was measured to confirm the modification efficiency. The results are shown in Tables 1 and 2. The modification efficiency was determined by the introduction rate, which was calculated using the following formula: introduction rate (%) = (amount introduced) / (amount added) x 100

[0061]

[0062]

[0063] From the results shown in Tables 1 and 2, it can be seen that Lewis acid (BF ３ It was found that when a protonic acid catalyst (such as a heteropoly acid) was used, the amount of hydroxyl group-containing organic compound introduced was small, whereas when the protonic acid catalyst (such as a heteropoly acid) used in the present invention was used, the amount of hydroxyl group-containing organic compound introduced was large. This shows that the production method of the present invention makes it possible to easily modify polyacetal resins and to obtain a variety of modified polyacetal resins.

[0064] The production method of the present invention is believed to enable the introduction of not only low molecular weight compounds but also polymeric compounds that are incompatible with polyacetal resins, and it is expected that the resulting modified polyacetal will exhibit various functions due to changes in the compatibility between the resulting modified polyacetal and various polymeric compounds.

[0065] A Polymerization device B Extruder X Position before entering the extruder Y Position midway through the extruder Z Modified polyacetal resin

Claims

1. A method for producing a modified polyacetal resin, comprising at least the steps of: (1) polymerizing a monomer using a protonic acid catalyst to produce a crude polyacetal polymer; and (2) deactivating the protonic acid catalyst and reacting the crude polyacetal polymer with an organic compound having a hydroxyl group.

2. The method for producing a modified polyacetal resin according to claim 1, wherein the protonic acid catalyst is selected from the group consisting of heteropolyacids and mixtures of heteropolyacids and their salts.

3. The method for producing a modified polyacetal resin according to claim 1 or 2, wherein the deactivator for deactivating the protonic acid catalyst is an amine compound, a quaternary ammonium compound or an alkali metal salt.