Method for producing modified polyacetal resin

Abstract

The object of the present invention is to provide a novel method for producing polyacetal resins that can easily modify polyacetal resins and provide various modified polyacetal resins. [Solution] The object of the present invention is achieved by a method for producing a modified polyacetal resin, which comprises at least the following steps: step (1) of polymerizing monomers with a protonic acid catalyst to produce a crude polyacetal polymer; and step (2) of deactivating the protonic catalyst while reacting the crude polyacetal polymer with an organic compound having a hydroxyl group.

Description

Technical Field

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

[0002] Conventionally, as a modification method for introducing a specific structural unit or functional group into the main chain or terminal of a polyacetal resin, a method of using trioxane as a main monomer and performing cationic copolymerization with a comonomer copolymerizable therewith is generally known. For example, a method of melt-kneading a polyacetal resin with a polymer having an active hydrogen atom or a glycidyl group in the molecule before deactivating the cationic polymerization catalyst is known (Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2005-105103 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In recent years, the versatility of polyacetal resins has expanded, and modified polyacetal resins have been required according to their applications. However, there are restrictions on comonomers to be copolymerized and compounds to react with the terminal, and it is currently difficult to carry out desired modifications.

[0008] An object of the present invention is to provide a method for producing a polyacetal resin which can easily modify a polyacetal resin and provide various modified polyacetal resins.

[0009] Solutions for solving problems

[0010] The present invention is achieved as follows.

[0011] 1. A method for producing a modified polyacetal resin, comprising at least the following steps:

[0012] Step (1), polymerizing the monomers using a protonic acid catalyst to produce a crude polyacetal polymer; and

[0013] In step (2), the protonic acid catalyst is deactivated and at the same time, the crude polyacetal polymer is reacted with an organic compound having a hydroxyl group.

[0014] 2. The method for producing a modified polyacetal resin according to (1) above, wherein the protonic acid catalyst is selected from a heteropoly acid or a mixture of a heteropoly acid and a salt thereof.

[0015] 3. The method for producing a modified polyacetal resin according to (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.

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to provide a method for producing a polyacetal resin which can easily modify a polyacetal resin and provide various modified polyacetal resins. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram showing a manufacturing process according to one embodiment of the present invention. DETAILED DESCRIPTION

[0019] Hereinafter, specific embodiments of the present invention will be described in detail. It should be noted that the present invention is not limited to the following embodiments at all, and can be implemented with appropriate changes within the scope of the purpose of the present invention.

[0020] The method for producing a modified polyacetal resin of the present invention comprises the following steps: step (1) of polymerizing a monomer using a protonic acid catalyst to produce a crude polyacetal polymer; and step (2) of deactivating the protonic acid catalyst while reacting the crude polyacetal polymer with an organic compound having a hydroxyl group.

[0021] <Step (1): Step of producing a crude polyacetal polymer>

[0022] Step (1) is a step of polymerizing monomers with a protonic acid catalyst to produce a crude polyacetal polymer. The "crude polyacetal polymer" of the present invention refers to a polymer in a state where the monomers are polymerized and the catalyst has not yet been deactivated, and refers to a polymer with a polymerization rate of 60% or more. Preferably, the polymerization rate is 65% or more. Here, "polymerization rate" refers to a value expressing the amount of the polymer obtained after the polymerization reaction relative to the amount of the monomers used, expressed as 100%.

[0023] "monomer"

[0024] In the present invention, there is no particular limitation on the monomers that can be used in the manufacture of the modified polyacetal resin, but trioxane is preferably used 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-trioxane, and 1,4-butanediol formal. Among these, 1,3-dioxolane is preferred from the viewpoint of manufacture.

[0025] Furthermore, as the comonomer, compounds having two or more epoxy groups in the molecule such as butanediol diglycidyl ether, compounds having glycidyl groups such as glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether, compounds having epoxy groups such as 1,3-butadiene diepoxy compounds, 1,4-pentanediol diepoxy compounds, 1,5-hexadiene diepoxy compounds, 1,6-heptadiene diepoxy compounds, 1,7-octadiene diepoxy compounds, 1,8-nonadiene diepoxy compounds, 1,9-decane diepoxy compounds, 1,10-undecane diepoxy compounds, and 1,11-dodecane diepoxy compounds, and compounds having alicyclic epoxy groups such as 2-(3,4-epoxycyclohexyl)ethyl ester can also be used. Thus, a polyacetal copolymer having a branched structure or a crosslinked structure can be obtained.

[0026] In the present invention, the content of the comonomer is preferably in the range of 0.01 to 20 parts by mass, more preferably in the range of 0.05 to 5 parts by mass, relative to 100 parts by mass of trioxane. If the content of the comonomer is 0.01 parts by mass or more relative to 100 parts by mass of trioxane, the polymerization can be stably carried out. In addition, if the content of the comonomer is 20 parts by mass or less relative to 100 parts by mass of trioxane, the decrease in the crystallization rate of the polymer chain and the decrease in the degree of crystallinity can be suppressed.

[0027] Protonic Acid Catalyst

[0028] Examples of the protonic acid catalyst that can be used in the present invention include heteropolyacids, mixtures of heteropolyacids and salts thereof, isopolyacids, and perfluoroalkanesulfonic acids.

[0029] Examples of heteropolyacids include phosphomolybdic acid, phosphotungstic acid, phosphomolybdic tungstic acid, phosphomolybdic vanadic acid, phosphomolybdic tungstic vanadic acid, phosphotungstic vanadic acid, silicotungstic acid, silicomolybdic acid, silicotungstic acid, silicotungstic vanadic acid, etc. Heteropolyacids are preferably any one or more of silicomolybdic acid, silicotungstic acid, phosphomolybdic acid or phosphotungstic acid. By using heteropolyacids, good polymerization stability is obtained.

[0030] As the salt of the heteropoly acid, an alkali metal salt is preferred. Examples of the alkali metal salt of the heteropoly acid 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.

[0031] The mass mixing ratio of the heteropolyacid and its salt (heteropolyacid salt / heteropolyacid) is preferably 10 or less, more preferably 5 or less. If the mass mixing ratio exceeds 10, the amount of catalyst used increases, and thus hydroxyl terminals that become a source of formaldehyde generation are excessively generated, which deteriorates the quality of the polymer, which is not preferred.

[0032] Examples of isopolyacids include isopolytungstic acid exemplified in paratungstic acid, metatungstic acid, isopolymolybdic acid exemplified in paramolybdic acid, metamolybdic acid, isopolyvanadic acid, isopolyvanadic acid, etc. Among these, isopolytungstic acid is preferably used. By using isopolytungstic acid, good polymerization stability is obtained.

[0033] Examples of perfluoroalkanesulfonic acids include trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, nonafluorobutanesulfonic acid, undecafluoropentanesulfonic acid, tridecafluorohexanesulfonic acid, pentafluoroheptanesulfonic acid, and heptadecafluorooctanesulfonic acid. Among these, trifluoromethanesulfonic acid is preferred. By using trifluoromethanesulfonic acid, good polymerization stability can be obtained.

[0034] In the present invention, the amount of the proton acid catalyst can be appropriately adjusted according to its type to regulate the polymerization reaction. Usually, the amount of the proton acid catalyst is preferably in the range of 0.05 to 100 ppm (hereinafter represented by mass / mass ppm) relative to the total amount of the monomer, and more preferably in the range of 0.1 to 50 ppm. If the amount of the proton acid catalyst is 0.05 to 100 ppm relative to the total amount of the monomer, the polymerization can be fully carried out, so it is easy to obtain the desired degree of polymerization. On the other hand, if the amount of the proton acid catalyst exceeds 100 ppm relative to the total amount of the monomer, the hydroxyl end that becomes the source of formaldehyde generation becomes excessively generated, and the quality of the polymer is reduced, so it is not preferred.

[0035] In order to carry out the reaction uniformly, the protonic acid catalyst is preferably diluted with an inactive solvent that has no adverse effect on the polymerization and added to the main monomer and / or comonomer for use. Examples of the inactive solvent include methyl formate, ethyl formate, methyl acetate, ethyl acetate, butyl acetate, acetone, 2-butanone, methyl isobutyl ketone, etc.

[0036] The protonic acid catalyst is suitably dissolved in the above-mentioned inert solvent at a concentration of 1 to 30 mass / mass%, but is not limited thereto. In addition, the following method is preferred: a predetermined amount of the above-mentioned protonic acid catalyst is pre-mixed with a part or the total amount of any one or more of the above-mentioned main monomer, comonomer, molecular weight modifier, etc., and the solution is added to the polymerization system to carry out polymerization.

[0037] 《Molecular weight regulator》

[0038] In the production of the crude polyacetal copolymer of the present invention, it is preferred to use a molecular weight modifier in addition to the above-mentioned components to adjust the molecular weight. As the molecular weight modifier, a chain transfer agent known in cationic polymerization can be used.

[0039] Examples of chain transfer agents include linear formals such as methylal, acetal, and dibutoxymethane, alcohols such as methanol, ethanol, and ethylene glycol, and water. Of these, methylal, acetal, and dibutoxymethane that do not form unstable terminals are preferred. The amount added is preferably 50 to 2000 ppm relative to the total monomer.

[0040] 《Method for producing crude polyacetal polymer》

[0041] The crude polyacetal polymer of the present invention is obtained as follows: a mixed solution containing the above-mentioned trioxane, 1,3-dioxolane, a molecular weight regulator and a protonic acid catalyst is continuously supplied to a polymerization reaction device (continuous twin-screw paddle screw extruder type) having a jacket on the outside of the main body for passing a medium for heating or cooling, and polymerization is carried out for a predetermined time to obtain the crude polyacetal polymer.

[0042] <Step (2): A step of deactivating the protonic acid catalyst and reacting the crude polyacetal polymer with an organic compound having a hydroxyl group>

[0043] Step (2) is a step of adding a deactivating agent to the crude polyacetal polymer obtained in the step (1) to deactivate the residual protonic acid catalyst and stabilize the unstable terminal of the crude polyacetal polymer, and reacting the crude polyacetal polymer with an organic compound having a hydroxyl group. This step can introduce a residue of an organic compound having a hydroxyl group into the crude polyacetal polymer to modify the polymer, and by changing the addition conditions of the deactivating agent to adjust the deactivation amount of the protonic acid catalyst, the degree of modification can be adjusted.

[0044] Here, “while deactivating the protonic acid catalyst, reacting the crude polyacetal polymer with the organic compound having a hydroxyl group” refers not only to the case where the deactivator and the organic compound having a hydroxyl group are added to the reaction system at the same time and react with the crude polyacetal polymer, but also to the case where the reaction of the deactivator with the crude polyacetal polymer and the reaction of the organic compound having a hydroxyl group with the crude polyacetal polymer are respectively carried out simultaneously in the reaction system even if the timing of adding the deactivator and the organic compound having a hydroxyl group to the reaction system is not the same. For example, it also includes the case where the organic compound having a hydroxyl group is first added and reacted with the crude polyacetal polymer, and the deactivator is added to the reaction system in the middle of the reaction; and the case where the addition is in the reverse order.

[0045] As a method for adding the organic compound having a hydroxyl group and the deactivating agent to the crude polyacetal polymer obtained in step (1), a known method such as a batch method or a continuous method can be appropriately selected.

[0046] Deactivation Agent

[0047] The deactivating agent that can be used in the present invention is not particularly limited. From the viewpoint that the deactivating agent can be directly added to the crude polyacetal polymer and melt-kneaded under heating to deactivate the protonic acid catalyst and stabilize the unstable ends of the crude polyacetal polymer, the deactivating agent preferably contains at least one selected from amine compounds, compounds having a quaternary ammonium group, carbonates, bicarbonates or carboxylates of alkali metal elements or alkaline earth metal elements, or hydrates thereof. In addition, two or more of these may be used in combination.

[0048] Examples of amine compounds include primary amine compounds such as methylamine, ethylamine, propylamine, isopropylamine, and butylamine, secondary amine compounds such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, and dibutylamine, and tertiary amine compounds such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, and tributylamine. Examples of compounds having a quaternary ammonium group include choline or choline salts. Among these, choline or choline salts are preferred.

[0049] Examples of carbonates, bicarbonates or carboxylates of alkali metal elements or alkaline earth metal elements or hydrates thereof include sodium formate, sodium acetate, potassium carbonate, sodium carbonate, sodium bicarbonate, disodium succinate, sodium laurate, sodium palmitate, sodium stearate or calcium stearate. Among these, sodium carbonate, sodium bicarbonate and sodium stearate are preferred. These may be used alone or in combination of two or more.

[0050] The amount of the deactivator added is not particularly limited, but is preferably 0.002 to 1.0 milliequivalent relative to 1 kg of the crude polyacetal copolymer. When the amount is within the range of 0.002 to 1.0 milliequivalent, discoloration of the obtained polymer can be suppressed.

[0051] Organic compounds with hydroxyl groups

[0052] Examples of organic compounds having hydroxyl groups (hereinafter also referred to as hydroxyl-containing organic compounds) that can be used in the present invention include organic compounds having alcoholic hydroxyl groups. Multiple hydroxyl groups can exist in one compound. For example, there can be mentioned: alcohols having 1 to 34 carbon atoms, polyalkylene oxides having hydroxyl terminals and a number average molecular weight of 1000 or less (such as ethylene oxide, propylene oxide, etc.), polyethylene glycols (PEG) having an average molecular weight of 600 or less (such as PEG600, PEG400, PEG300, etc.).

[0053] The organic compound having a hydroxyl group can be appropriately selected according to the application of the polyacetal resin, and the degree of modification can also be appropriately selected.

[0054] 《Method for producing modified polyacetal resin》

[0055] The outline of the method for producing the modified polyacetal resin of the present invention is as follows: Figure 1 Provide explanation. Figure 1A is a polymerization device for polymerizing the monomer in the "step (1): step of producing a crude polyacetal polymer", and B is an extruder for reacting the crude polyacetal polymer with an organic compound having a hydroxyl group and performing a deactivation treatment of the polymerization catalyst in the "step (2): step of deactivating the protonic acid catalyst and reacting the crude polyacetal polymer with an organic compound having a hydroxyl group". Figure 1 X and Y in the figure indicate the position where the deactivating agent is added. Specifically, X refers to the position where the deactivating agent is added before entering the extruder (before melt kneading), and Y refers to the position where the deactivating agent is added in the middle of the extruder.

[0056] Next, the above-mentioned treatment method for "deactivating the protonic acid catalyst" (hereinafter also referred to as catalyst deactivation treatment) and the process of modifying the crude polyacetal polymer are described. Specifically, the catalyst deactivation treatment is as follows: Figure 1 The positions of X are as shown in (1) to (4) below. A deactivator or a solution of a deactivator is added to a crude polyacetal polymer, and the two are melt-kneaded in an extruder B.

[0057] (1) The deactivating agent is added directly to the crude polyacetal polymer.

[0058] (2) A solution containing a deactivating agent is added to the crude polyacetal polymer.

[0059] (3) A solution containing a deactivating agent is mixed with a previously prepared polyacetal resin powder, and then added to a crude polyacetal polymer.

[0060] (4) The deactivating agent is directly mixed with the polyacetal resin powder prepared in advance, and then added to the crude polyacetal polymer.

[0061] In addition, as shown in the following (5) to (8), Figure 1 The position Y shown can be added to the crude polyacetal polymer in a state where it is melt-kneaded in the extruder B.

[0062] (5) A solution containing a deactivating agent is added to the portion in a melt-kneaded state from the middle of the extruder B by injection or the like.

[0063] (6) The deactivating agent is added directly from the middle of the extruder B to the portion in the melt kneading state.

[0064] (7) After mixing the solution containing the deactivating agent with the previously prepared polyacetal resin powder, the dispersed powder is added from the middle of the extruder B to the portion in the melt kneading state.

[0065] (8) After the deactivator is directly mixed with the previously prepared polyacetal resin powder, the dispersed powder is added from the middle of the extruder B to the portion in the melt kneading state.

[0066] The mixing of the crude polyacetal polymer or polyacetal resin powder and the deactivator shown in (1) to (8) can also be performed using a conventional mixer such as a horizontal cylindrical mixer, a V-type mixer, a ribbon mixer, a paddle mixer, or a high-speed flow mixer. The molten resin discharged from the discharge die (not shown) provided in the discharge portion of the extruder B is cooled and cut into pellets to obtain a modified polyacetal resin.

[0067] Regarding the timing of adding the deactivating agent in the catalyst deactivation treatment of (1) to (8), the hydroxyl-containing organic compound of the present invention and the deactivating agent may be added simultaneously or separately.

[0068] When the hydroxyl-containing organic compound and the deactivating agent are added simultaneously, the hydroxyl-containing organic compound and the deactivating agent may be directly added at the same position (X or Y), or may be mixed with a pre-prepared polyacetal resin powder and then added.

[0069] When the hydroxyl-containing organic compound and the deactivator are added separately, the hydroxyl-containing organic compound directly or mixed with a pre-prepared powder of polyacetal resin is fed from X together with the crude polyacetal polymer into extruder B and melt-kneaded, and the deactivator can be added to the melt-kneading section (not shown) by the methods described in (5) to (8) above. Alternatively, the deactivator can be added to the crude polyacetal polymer from X before melt-kneading by the methods described in (1) to (4) above, and then melt-kneaded in extruder B, and the hydroxyl-containing organic compound directly or mixed with a pre-prepared powder of polyacetal resin is added from Y to the melt-kneading section (not shown). It should be noted that when the hydroxyl-containing organic compound and the deactivator are added separately and mixed, it is preferred to add the hydroxyl-containing organic compound before melt-kneading.

[0070] The modification of the present invention is specifically caused in the crude polyacetal polymer polymerized using a protonic acid catalyst, and the modification efficiency is extremely low when Lewis acid such as boron trifluoride is used as a catalyst. The modification of the present invention can be specifically performed when a protonic acid catalyst is used.

[0071] In the present invention, the reaction with the organic compound having a hydroxyl group and the catalyst deactivation reaction are competitive reactions. Therefore, the deactivation treatment can be used to adjust the progress of the reaction between the crude polyacetal polymer and the organic compound having a hydroxyl group and to adjust the degree of modification.

[0072] <Other Process>

[0073] The present invention may also include other steps, for example, a step of adding various additives from the middle of an extruder and performing melt kneading, or a step of adding various additives to a pelletized polyacetal resin and then performing melt kneading again.

[0074] Example

[0075] Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to these.

[0076] <Process (1)>

[0077] In step (1), polymerization is carried out as follows to produce a crude polyacetal polymer. A continuous twin-screw paddle screw extruder is used as polymerization device A. The polymerization device A is provided with a jacket (not shown) on the outside of the main body for passing a medium for heating or cooling. In addition, the main body is divided into upper and lower parts, and the upper part is openable. Inside the polymerization device A, two rotating shafts with a plurality of paddles for stirring and propulsion are provided along the length direction.

[0078] A mixed solution 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 modifier was continuously supplied per unit time to the main body portion heated by passing a medium at 80° C. through the temperature-controlled jacket, and a polymerization catalyst was supplied thereto.

[0079] The content of the polymerization catalyst was 4 ppm in the case of a combination of phosphotungstic acid and trifluoromethanesulfonic acid, and 4 ppm in the case of phosphotungstic acid and its salt, H5PV2W 10 O 40 The concentration of the combination of (HPA) and phosphotungstic acid salt was set to 6 ppm, and the concentration of boron trifluoride diethyl ether was set to 30 ppm (relative to all monomers, unit: mass ppm), and these solutions were continuously added to carry out copolymerization. It should be noted that the concentration of boron trifluoride diethyl ether as a polymerization catalyst is a value calculated in terms of boron trifluoride.

[0080] <Process (2)>

[0081] In step (2), the flaky crude polyacetal polymer discharged from the polymerization apparatus A is added with an organic compound having a hydroxyl group and a deactivating agent as shown in Tables 1 and 2, and melt-kneaded in a twin-screw extruder with a vent at a barrel temperature of 210 degrees to obtain a pelletized modified polyacetal resin. The organic compound having a hydroxyl group and the deactivating agent are added as follows.

[0082] When the deactivator is added at position X: an organic compound having a hydroxyl group and a deactivator as shown in Tables 1 and 2 are added to 2 parts by mass of a polyacetal resin powder relative to 100 parts by mass of a crude polyacetal polymer, and the mixture is added from position X together with the crude polyacetal polymer.

[0083] When the deactivator is added at position Y: an organic compound having a hydroxyl group shown in Tables 1 and 2 is added to 2 parts by mass of a polyacetal resin powder relative to 100 parts by mass of a crude polyacetal polymer, and the mixture is mixed, and the resulting substance is added together with the crude polyacetal polymer from position X, and then the deactivator shown in Tables 1 and 2 is added from position Y.

[0084] 《Compounds listed in Tables 1 and 2》

[0085] [Organic compound having hydroxyl group]

[0086] OH1: Docosyl alcohol (carbon number 22)

[0087] OH2: Pentanediol (carbon number 5)

[0088] OH3: Polyethylene glycol 400 (PEG400)

[0089] [catalyst]

[0090] The following catalysts were added in the form of solutions indicated in parentheses, respectively.

[0091] PWA: phosphotungstic acid (0.2wt% methyl formate solution)

[0092] PWA+salt: an equal mass mixture of phosphotungstic acid and sodium phosphotungstic acid (0.2wt% methyl formate solution)

[0093] HPA+salt: H5PV2W 10 O 40 An equal mass mixture with sodium phosphotungstate (0.2wt% methyl formate solution)

[0094] TFMSA: trifluoromethanesulfonic acid (0.2 wt% cyclohexane solution)

[0095] BF3: Boron trifluoride diethyl ether (boron trifluoride is a 1.5 wt% cyclohexane solution)

[0096] [Deactivating agent]

[0097] The amount added was 10 ppm in all cases. It should be noted that solids at room temperature were added as solids, and those referred to as "aq." in Tables 1 and 2 were added as aqueous solutions (concentration: 0.5 mg / mL).

[0098] ·StNa: Sodium stearate

[0099] Na2CO3: sodium carbonate,

[0100] K2CO3: Potassium carbonate

[0101] ·choline

[0102] ·TEA: Triethylamine

[0103] <Modification evaluation>

[0104] 0.2 g of the modified polyacetal resin in pellet form obtained by step (1) and step (2) is dissolved in 4 ml of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), and 8 ml of methanol is added thereto while stirring to reprecipitate. The reprecipitated resin is filtered and recovered, and then dried. The dried polyacetal resin is subjected to the above treatment again, and the obtained resin is used as a sample. 30 mg of the obtained sample is dissolved in deuterated HFIP (0.6 ml), and 1H-NMR (nuclear magnetic resonance) measurement is performed using AVANCE III 400 (manufactured by Bruker Biospin) equipped with a Cryo probe at a temperature setting of 318 K and 128 accumulations. The amount of hydroxyl-containing organic compound introduced is determined from the peak areas of the oxymethylene and oxyethylene derived from the polyacetal polymer and the peak area of ​​the hydroxyl-adjacent methylene of the hydroxyl-containing organic compound in the obtained NMR spectrum.

[0105] For each material in which 5000 ppm of a hydroxyl-containing organic compound and a crude polyacetal polymer were melt-kneaded, the amount of the hydroxyl-containing organic compound introduced was measured to confirm the modification efficiency. The results are shown in Tables 1 and 2. It should be noted that the modification efficiency is determined based on the introduction rate. The introduction rate is calculated using the following formula.

[0106] Introduction rate (%) = (introduction amount) ÷ (addition amount) × 100

[0107] [Table 1]

[0108]

[0109] [Table 2]

[0110]

[0111] As shown in Tables 1 and 2, when Lewis acid (BF3) is used as a polymerization catalyst, the amount of hydroxyl-containing organic compound introduced decreases, but the amount of hydroxyl-containing organic compound introduced increases in the protonic acid catalyst (heteropolyacid, etc.) used in the present invention. It can be seen from this that if the production method of the present invention is used, the polyacetal resin can be easily modified to obtain various modified polyacetal resins.

[0112] Industrial Applicability

[0113] It is considered that according to the production method of the present invention, not only low molecular weight compounds but also high molecular weight compounds incompatible with the polyacetal resin can be introduced, and the resulting modified polyacetal can be expected to exhibit functions due to changes in compatibility with various high molecular weight compounds.

[0114] Description of Reference Numerals

[0115] A polymerization device

[0116] B Extruder

[0117] X Position before entering the extruder

[0118] Y Extruder midway position

[0119] Z modified polyacetal resin

Claims

1. A method for producing a modified polyacetal resin, comprising at least the following steps: Step (1), polymerizing monomers using a heteropolyacid or a heteropolyacid and a salt thereof as a protonic acid catalyst to produce a crude polyacetal polymer; and In step (2), the crude polyacetal polymer is reacted with an organic compound having a hydroxyl group selected from any one of an alcohol having 5 to 34 carbon atoms, a polyalkylene oxide having a hydroxyl terminal and a number average molecular weight of 1,000 or less, and a polyethylene glycol having a number average molecular weight of 600 or less while deactivating the protonic acid catalyst under melt kneading.

2. The method for producing a modified polyacetal resin according to claim 1, wherein: The heteropoly acid and its salt are phosphotungstic acid and sodium phosphotungstate, or H5PV2W 10 O 40 With sodium phosphotungstate.

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

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