JP2011195746A - Method for producing polyacetal resin composition, and polyacetal resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyacetal resin composition that is excellent in productivity in continuous extrusion for a long time and can effectively suppress thermal decomposition and degradation of raw materials.SOLUTION: The method for producing a polyacetal resin composition includes: a step 1 of mixing a polyacetal resin homopolymer (A) and a nitrogen-containing compound (B) capable of capturing formaldehyde in a state of powder to obtain a powdery mixture (X); a step 2 of further adding a polyacetal resin homopolymer (A) to the obtained powdery mixture (X) to obtain another powdery mixture (S); and a step 3 of melting and kneading the obtained powdery mixture (S).

Description

  The present invention relates to a method for producing a polyacetal resin composition and a polyacetal resin composition.

  The polyacetal resin is a crystalline resin and is a resin material having excellent rigidity, strength, toughness, slidability, and creep properties. The use of polyacetal resin covers a wide range, such as materials for mechanical parts such as automobile parts, electric / electronic parts and industrial parts.

  These various mechanical parts are normally continuously produced as follows. First, various additives such as a stabilizer are added to the polyacetal resin, and the mixture is melt-kneaded by an extruder or the like to obtain pellets of the polyacetal resin composition. A desired molded product is injection-molded using the pellets of the obtained polyacetal resin composition, and various mechanical parts are continuously produced. When such continuous production is performed over a long period of time, the polyacetal resin is thermally decomposed by being melt-kneaded with an extruder or the like at a predetermined residence time and temperature to release formaldehyde. And the emitted formaldehyde turns into a carbide | carbonized_material by saccharification reaction (formose reaction). Further, various additives such as a stabilizer added in the polyacetal resin are melt-kneaded at a predetermined residence time and temperature by an extruder or the like, so that modification due to so-called burning occurs and a modified product is obtained.

  When a polyacetal resin molded product is used continuously for a long period of time, stress at the time of use of the molded product concentrates at a location where the carbide and modified product are present, and becomes a starting point of fracture. Therefore, in the molded article obtained from the polyacetal resin composition in which the carbide and modified product are mixed, the inherent durability of the polyacetal resin is hindered.

  Therefore, when various mechanical parts are continuously produced using the polyacetal resin composition, the temperature at which the raw material containing the polyacetal resin is melt-kneaded by an extruder or the like is reduced to the vicinity of the melting point of the polyacetal resin as much as possible, and the residence time is further reduced. Under the conditions such as suppression, pellets of the polyacetal resin composition are produced, and generation of the above-described carbide and modified product is suppressed. Further, measures such as periodically washing a melt-kneading apparatus such as an extruder are taken to prevent the carbide and modified product from being mixed into the molded product. Furthermore, a process inspection such as a visual inspection is performed to check whether foreign matters such as the above-mentioned carbides and modified products are mixed in a molded article using the polyacetal resin composition, and a great deal of labor is required for quality control. The current situation is.

  Conventionally, as a method for improving the thermal stability of a polyacetal resin, a method of adding and blending a ternary copolymer polyamide (for example, see Patent Document 1), a method of adding and blending a poly-β-alanine polymer (for example, a patent) A method of adding and blending two or more polyamide resins (for example, see Patent Document 3) has been proposed. In recent years, there has been a demand for further reduction in the amount of volatile organic compounds (VOC) containing formaldehyde, mainly in automobile interior parts. Therefore, an attempt has been made to add a formaldehyde emission inhibitor and reduce the amount of formaldehyde released from the molded product (see, for example, Patent Document 4).

Japanese Patent Publication No.34-005440 Japanese Patent Laid-Open No. 02-247247 JP 51-064559 A JP-A-10-298401

  According to the above conventionally proposed method, when a raw material containing a polyacetal resin is continuously melted and kneaded with an extruder or the like in a short time, the thermal decomposition of the polyacetal resin and the modification of various additives can be suppressed. And the molded article obtained from a polyacetal resin composition does not impair the durability derived from the polyacetal resin which it has originally.

  However, even when the raw material containing the polyacetal resin is continuously melted and kneaded with an extruder or the like even by the above-mentioned conventionally proposed methods, formaldehyde-derived carbides generated by the thermal decomposition of the polyacetal resin, stabilizers, etc. The generation of denatured products due to various additives cannot be completely suppressed. And, foreign substances such as generated carbides and modified products clog the eyes of the extruder die, for example, and the die pressure of the extruder rises, so it is difficult to continuously produce a polyacetal resin composition for a long period of time. Become. Furthermore, when a carbide and a modified product are mixed in the polyacetal resin composition, as described above, the long-term durability of the obtained polyacetal resin molded article is hindered.

  Therefore, the present invention generates formaldehyde-derived carbides generated by thermal decomposition of polyacetal resin and modified products caused by various additives such as stabilizers even when melt-kneading is performed continuously by an extruder or the like for a long time. It aims at providing the manufacturing method of the polyacetal resin composition which can be suppressed effectively, and the polyacetal resin composition obtained by the said manufacturing method.

  As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have performed a specific process before performing melt kneading with an extruder or the like, thereby performing melt kneading with an extruder or the like continuously for a long time. It is found that the generation of carbides caused by formaldehyde generated by the thermal decomposition of the polyacetal resin and modified products caused by various additives such as stabilizers can be effectively suppressed, and the present invention is completed. It came to.

  That is, the present invention is as follows.

[1] Step 1 of mixing a polyacetal resin homopolymer (A) and a nitrogen-containing compound (B) having a formaldehyde scavenging ability in a powder state to obtain a powdery mixture (X);
Step 2 of further obtaining a powdery mixture (S) by further mixing the polyacetal resin homopolymer (A) with the obtained powdery mixture (X);
And a step 3 of melt-kneading the obtained powdery mixture (S). A method for producing a polyacetal resin composition, comprising:

  [2] The method for producing a polyacetal resin composition according to [1], wherein the mixing in the step 1 is performed at a pressure of 1 to 100 kPa and a temperature of 25 to 70 ° C.

  [3] The amount of the nitrogen-containing compound (B) added in the step 1 is 10 to 1000 parts by mass with respect to 100 parts by mass of the polyacetal resin homopolymer (A) [1] or [2 ] The manufacturing method of the polyacetal resin composition of description.

  [4] The method for producing a polyacetal resin composition according to any one of [1] to [3], wherein the mixing in the step 1 is performed with a planetary motion type stirring mixer.

  [5] The polyacetal resin homopolymer (A) is a particle having a particle diameter of 500 μm or less, and the ratio of particles having a particle diameter of 100 to 250 μm in the polyacetal resin homopolymer (A) is 30% by mass or more. The method for producing a polyacetal resin composition according to any one of [1] to [4].

  [6] The method for producing a polyacetal resin composition according to any one of [1] to [5], wherein the nitrogen-containing compound (B) in the step 1 is an acrylamide polymer (B-1). .

  [7] Any of [1] to [5], wherein the nitrogen-containing compound (B) in Step 1 is a mixture of an acrylamide polymer (B-1) and a hydrazide compound (B-3). The manufacturing method of the polyacetal resin composition as described in 1 above.

  [8] The polyacetal according to [6] or [7], wherein the acrylamide polymer (B-1) includes a structure represented by the following general formula (I) and / or the following general formula (II): A method for producing a resin composition.

[9] A polyacetal resin composition obtained by the method for producing a polyacetal resin composition according to any one of [1] to [8].

  According to the present invention, even when melt kneading with an extruder or the like continuously for a long time, generation of carbides caused by formaldehyde caused by thermal decomposition of polyacetal resin and modified products caused by various additives such as stabilizers are generated. It can suppress effectively and can manufacture a polyacetal resin composition stably for a long period of time.

  Moreover, if the polyacetal resin composition obtained by the manufacturing method of the present invention is used, a molded product with a small amount of formaldehyde emission can be stably and efficiently manufactured for a long period of time.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described. The present invention is not limited to the following description, and various modifications can be made within the scope of the gist thereof.

[Method for producing polyacetal resin composition]
In the method for producing a polyacetal resin composition according to the present embodiment, the polyacetal resin homopolymer (A) and the nitrogen-containing compound (B) having formaldehyde scavenging ability are mixed in a powder state to obtain a powdery mixture (X) 1 Step 2 for further mixing the polyacetal resin homopolymer (A) with the obtained powder mixture (X) to obtain a powder mixture (S), and melt kneading the obtained powder mixture (S) Step 3 is included.

  The steps 1 to 3 in the method for producing the polyacetal resin composition of the present embodiment will be described in more detail.

<Step 1>
The step 1 is a step of obtaining a powdery mixture (X) by mixing the polyacetal resin homopolymer (A) and the nitrogen-containing compound (B) having formaldehyde scavenging ability in a powder state. Before melt-kneading the raw material by an extruder or the like, a nitrogen-containing compound is prepared by previously mixing a part of the raw material polyacetal resin homopolymer (A) and a nitrogen-containing compound (B) having a formaldehyde scavenging ability in a powder state. Since the aggregation of (B) can be suppressed, the formaldehyde scavenging ability of the nitrogen-containing compound (B) is effectively exhibited. As a result, even if melt kneading is carried out continuously using an extruder or the like for a long time, the generation of carbides caused by formaldehyde caused by thermal decomposition of the polyacetal resin and modified products caused by additives such as nitrogen-containing compounds (B) are generated. It can suppress effectively and can manufacture a polyacetal resin composition stably for a long period of time. Moreover, the molded article obtained using the said polyacetal resin composition has few discharge | release amounts of formaldehyde.

  Moreover, in the said process 1, it is preferable to add another additive (C) with the nitrogen-containing compound (B) which has a polyacetal resin homopolymer (A) and formaldehyde capture | capture ability. By adding the above various additives (C), it is possible to effectively suppress the generation of modified products resulting from the various additives, and the extrusion productivity of the polyacetal resin composition tends to be more significantly improved. . Further, the amount of formaldehyde released from a molded product obtained using the polyacetal resin composition tends to be significantly reduced.

  The temperature at the time of mixing in the step 1 is preferably 25 to 70 ° C, more preferably 25 to 50 ° C, and further preferably 25 to 45 ° C. When the temperature at the time of mixing in the above step 1 is within the above range, aggregation of the nitrogen-containing compounds (B) due to an increase in heat of mixing can be suppressed. As a result, the amount of formaldehyde released from the finally obtained molded product tends to be reduced to a sufficiently satisfactory level. The temperature control during the mixing is performed by, for example, a method of flowing warm water or cooling water through a jacket portion installed in the stirring mixer in addition to adjusting the stirring rotation speed.

  The pressure during mixing in Step 1 is preferably 1 to 100 kPa, more preferably 1 to 80 kPa, and further preferably 1 to 50 kPa. When the pressure at the time of mixing in the above step 1 is within the above range, aggregation of the nitrogen-containing compound (B) having formaldehyde scavenging ability can be prevented, and the extrusion productivity of the polyacetal resin composition tends to be improved. . Moreover, it exists in the tendency which can reduce the amount of formaldehyde discharge | released from the molded article obtained using this polyacetal resin composition. Adjustment of the pressure is usually performed using nitrogen gas. Specifically, the pressure at the time of mixing is adjusted to be within the above range by introducing nitrogen gas into the stirring mixer.

  In the case of stirring and mixing, the stirring rotation speed is also considered to be effective in preventing aggregation of the nitrogen-containing compound (B) having a formaldehyde scavenging ability, similarly to the above pressure. The stirring rotation speed is adjusted so that the product temperature in the stirring mixer is in the range of 25 to 70 ° C, preferably in the range of 25 to 50 ° C, and more preferably in the range of 25 to 45 ° C.

  The mixing in the above step 1 is performed, for example, with a stirring mixer such as a Henschel mixer, a cone blender, a tumbler mixer, a two-shaft paddle mixer, a double cone mixer, or a rocking rotary mixer. However, it is sometimes difficult to control the product temperature in the stirring mixer. Therefore, it is particularly preferable that the mixing in the step 1 is performed by a conical screw type mixer, specifically, a planetary motion type stirring mixer.

  When the mixing in the step 1 is performed by a Henschel mixer, the rotation speed of the stirring blade can be increased, and the raw material can be uniformly dispersed in a short time. However, the temperature of the product in the stirring mixer rises rapidly, and the nitrogen-containing compound (B) having a formaldehyde scavenging ability easily aggregates. Therefore, the rotational speed of the rotor blades of the Henschel stirring mixer is slowed to prevent the product temperature in the stirring mixer from rising, or cooling water is supplied to the jacket part installed in the stirring mixer, so that the product temperature in the stirring mixer is reduced. To prevent aggregation of the nitrogen-containing compound (B) having formaldehyde scavenging ability. However, the aggregation of the nitrogen-containing compound (B) having a complete formaldehyde scavenging ability may not be prevented. As a result, the extrusion productivity of the polyacetal resin composition decreases, and the amount of formaldehyde released from the molded product obtained using the polyacetal resin composition may not be reduced to a sufficiently satisfactory level.

  The planetary motion type stirring mixer is an inverted conical vertical stirring mixer in which a screw-type stirring blade (2) that rotates along the side surface of the stirring mixer is installed on the rotation shaft (1) at the center of the stirring mixer. . The contents are uniformly mixed by the rotation of the screw type stirring blade (2) and the rotation of the rotary shaft (1), and the product temperature in the stirring mixer can be easily adjusted to a range of 25 to 70 ° C. Therefore, the raw materials can be uniformly dispersed, and the nitrogen-containing compound (B) having a formaldehyde scavenging ability is difficult to aggregate. As a result, the extrusion productivity of the polyacetal resin composition is lowered, and the amount of formaldehyde released from a molded product obtained using the polyacetal resin composition can be significantly reduced.

  When using a planetary motion type stirring mixer, it is preferable to adjust the rotational speed of the rotating shaft (1) in the range of 1 to 20 rpm and to adjust the rotational speed of the screw type stirring blade (2) in the range of 1 to 300 rpm. . As for the rotational speed of a rotating shaft (1), it is more preferable that it is 1-10 rpm. As for the rotational speed of a screw type stirring blade (2), it is more preferable that it is 1-200 rpm, and it is further more preferable that it is 1-100 rpm. The stirring and mixing time is not particularly limited, but is adjusted so that the temperature in the stirring and mixing machine is in the range of 25 to 70 ° C. The specific stirring and mixing time is preferably 1 to 50 hours, more preferably 1 to 30 hours, and further preferably 1 to 20 hours.

  In the above step 1, the addition amount of the polyacetal resin homopolymer (A) is preferably 10 to 90% by mass, more preferably 10 to 50% by mass with respect to 100% by mass of all raw materials. More preferably, it is -25 mass%.

  The amount of the nitrogen-containing compound (B) added in Step 1 is preferably 10 to 1000 parts by mass and more preferably 10 to 500 parts by mass with respect to 100 parts by mass of the polyacetal resin homopolymer (A). Preferably, it is 10-300 mass parts, More preferably, it is 10-100 mass parts. When the amount of the nitrogen-containing compound (B) added in Step 1 is within the above range, a polyacetal resin composition having a small amount of formaldehyde emission tends to be stably produced over a long period of time.

  In the above step 1, when the other additive (C) is mixed together with the polyacetal resin homopolymer (A) and the nitrogen-containing compound (B) having formaldehyde scavenging ability, the additive amount (C) is added to the polyacetal resin. It is preferable that it is 10-1000 mass parts with respect to 100 mass parts of homopolymer (A), It is more preferable that it is 10-500 mass parts, It is further more preferable that it is 10-300 mass parts, 10-300 The part by mass is particularly preferred.

  Hereinafter, the polyacetal resin homopolymer (A), the nitrogen-containing compound (B) having formaldehyde scavenging ability, and other additives (C) will be described in detail.

(Polyacetal resin homopolymer (A))
The polyacetal resin homopolymer (A) is an oxymethylene homopolymer having an oxymethylene structural unit having an oxymethylene group in the main chain and an unstable terminal group of the polymer stabilized by an ester group or an ether group. .

  In Step 1, the polyacetal resin homopolymer (A) is used in a powder state.

  The MFR value (based on ISO 1133) of the polyacetal resin homopolymer (A) is preferably 0.1 to 100 g / 10 minutes, more preferably 0.1 to 70 g / 10 minutes, More preferably, it is 45 g / 10 minutes.

  The polyacetal resin homopolymer (A) is preferably particles having a particle size of 500 μm or less, and the proportion of particles having a particle size of 100 to 250 μm in the polyacetal resin homopolymer (A) is preferably 30% by mass or more. Among them, the ratio of particles having a particle diameter of 100 to 250 μm is more preferably 40% by mass or more, and further preferably 50% by mass or more. The upper limit of the proportion of particles having a particle size of 100 to 250 μm is preferably 90% by mass or less.

  The polyacetal resin homopolymer (A) is more preferably a particle having a particle diameter of 500 μm or less, and further preferably a particle having a particle diameter of 300 μm or less. The lower limit of the particle diameter of the polyacetal resin homopolymer (A) is preferably 50 μm or more.

  When the particle diameter of the polyacetal resin homopolymer (A) exceeds 500 μm, the nitrogen-containing compound (B) having formaldehyde scavenging ability in the polyacetal resin homopolymer (A) is classified, and the nitrogen-containing compound having formaldehyde scavenging ability ( B) tends not to be uniformly dispersed. That is, the concentration distribution of the nitrogen-containing compound (B) having formaldehyde scavenging ability in the polyacetal resin composition tends to be non-uniform (concentration variation is large). As a result, a formaldehyde-derived carbide and a modified product derived from the nitrogen-containing compound (B) having formaldehyde-capturing ability are generated and tend to be mixed into the polyacetal resin composition. Moreover, since these carbide | carbonized_material and modified | denatured matter clog the eyes of an extruder die, die pressure rises and it becomes difficult to produce a polyacetal resin composition stably and continuously. Further, the amount of formaldehyde released from a molded product obtained using the polyacetal resin composition tends to increase.

  Even if the particle diameter of the polyacetal resin homopolymer (A) is 500 μm or less, the bulk density of the polyacetal resin homopolymer (A) is low when the ratio of the particle diameter of 100 to 250 μm is less than 30% by mass. Tend to be. Further, the nitrogen-containing compound (B) having the formaldehyde scavenging ability cannot be uniformly dispersed, and similarly to the above, a carbide caused by formaldehyde and a modified product caused by the nitrogen-containing compound (B) having formaldehyde capturing ability are generated. It becomes easy. As a result, it becomes difficult to stably and continuously produce a polyacetal resin composition. Further, the amount of formaldehyde released from a molded product obtained using the polyacetal resin composition tends to increase.

  The polyacetal resin homopolymer (A) is a particle having a particle diameter of 500 μm or less, and the ratio of the particle diameter of 100 to 250 μm is 30% by mass or more with respect to 100% by mass of all the particles of the polyacetal resin homopolymer (A). In this case, the continuous extrusion productivity of the polyacetal resin composition tends to be improved, and the amount of formaldehyde released from the molded product obtained using the polyacetal resin composition tends to be reduced.

  In the present embodiment, the ratio of the particle diameter in a specific range is obtained by the measurement method in Examples described later.

  The adjustment of the particle diameter of the polyacetal resin homopolymer (A) is a method of adjusting in the step of stabilizing unstable terminal groups of the resulting crude polyacetal resin homopolymer when the polyacetal resin homopolymer is obtained by polymerization, or After stabilizing the unstable terminal group, the polyacetal resin homopolymer (A) obtained can be adjusted by a method of pulverizing with a pulverizing mixer or the like.

  The method of adjusting the particle diameter of the polyacetal resin homopolymer (A) in the step of stabilizing the unstable terminal group of the crude polyacetal resin homopolymer is the method of adjusting the end of the crude polyacetal resin homopolymer that has not stabilized the polymer end group immediately after polymerization. It can adjust in the process of stabilizing. Specifically, the slurry concentration of the crude polyacetal resin homopolymer is adjusted with a hydrocarbon solvent such as n-hexane solvent so that the slurry concentration is 10 to 50% by volume, and this slurry is esterified with an esterifying agent such as acetic anhydride. The particle surface of the crude polyacetal resin homopolymer is melted at a temperature of 130 to 155 ° C. and in the range of 0.5 to 5 hours, and the crude polyacetal resin homopolymer is welded to adjust the particle diameter.

  On the other hand, the method of adjusting the particle size using a pulverizing mixer is to adjust the terminal stabilized polyacetal resin homopolymer into a pellet form by an extruder or the like, and then adjusting the particle size to a target using a pulverizing mixer. .

  Among these methods for adjusting the particle size, a method of adjusting the particle size of the polyacetal resin homopolymer (A) in the terminal stabilization treatment step is easy in the production process and is a preferable method.

(Nitrogen-containing compound having formaldehyde scavenging ability (B))
Examples of the nitrogen-containing compound (B) having formaldehyde scavenging ability include an acrylamide polymer (B-1), a polyamide polymer (B-2), a hydrazide compound (B-3), and an amino-substituted triazine compound (B-4). And urea compounds (B-5), amino acid compounds (B-6), guanidine compounds (B-7), imide compounds (B-8), and the like.

  These nitrogen-containing compounds (B) having formaldehyde capturing ability may be used alone or in combination of two or more.

  The nitrogen-containing compound (B) having formaldehyde scavenging ability may be the acrylamide polymer (B-1) alone, but is preferably a mixture containing at least the acrylamide polymer (B-1). More preferably, it is a mixture of (B-1) and hydrazide compound (B-3), and is a mixture of acrylamide polymer (B-1), polyamide polymer (B-2) and hydrazide compound (B-3). More preferably it is.

  The nitrogen-containing compound (B) having the formaldehyde scavenging ability described above includes the first group of acrylamide polymer (B-1) and polyamide polymer (B-2), hydrazide compound (B-3), and amino-substituted triazines. It is divided into the second group of compound (B-4), urea compound (B-5), amino acid compound (B-6), guanidine compound (B-7) and imide compound (B-8). .

  The first group and the second group can be added and blended alone in the polyacetal resin homopolymer (A), but it is more preferable to use the first group and the second group in combination.

  That is, the nitrogen-containing compound (B) having formaldehyde scavenging ability is at least one nitrogen-containing compound selected from the group (first group) consisting of the acrylamide polymer (B-1) and the polyamide polymer (B-2). Compound, hydrazide compound (B-3), amino-substituted triazine compound (B-4), urea compound (B-5), amino acid compound (B-6), guanidine compound (B-7) and imide It is preferably a mixture with at least one nitrogen-containing compound selected from the group (second group) consisting of the system compound (B-8).

  Among them, a preferable combination is a combination of a first group consisting of an acrylamide polymer (B-1) and a polyamide polymer (B-2) and a second group of a hydrazide compound (B-3), or an acrylamide polymer (B -1) A combination of the first group consisting of the polyamide polymer (B-2) and the urea compound (B-5). The most preferred combination is a combination of the first group consisting of the acrylamide polymer (B-1) and the polyamide polymer (B-2) and the second group of the hydrazide compound (B-3).

  The first group of nitrogen-containing compounds (B) having formaldehyde scavenging ability will be described in detail.

  The acrylamide polymer (B-1) is preferably an acrylamide polymer having a structure represented by the following general formula (I) and / or the following general formula (II).

Moreover, it is preferable that it is a crosslinked acrylamide polymer which introduce | transduced the monomer which has vinyl groups other than acrylamide as a copolymerization component in the molecular structure of an acrylamide polymer (B-1). Among these acrylamide polymers (B-1), an acrylamide polymer which is a crosslinked acrylamide polymer and has an average particle size of 10 μm or less is preferable. When such an acrylamide polymer (B-1) is used, the extrusion productivity of the polyacetal resin composition is improved, and the amount of formaldehyde released from the molded product obtained using the polyacetal resin composition tends to be reduced. is there. More preferred is an acrylamide polymer having an average particle size of 5 μm or less, and most preferred is a cross-linked acrylamide polymer having an average particle size of 3 μm or less.

  The crosslinking component of the acrylamide polymer (B-1) is a monomer having one or two vinyl groups, such as n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, 2 -Ethylhexyl methacrylate, cecil methacrylate, pentadecyl methacrylate, stearyl methacrylate, behenyl methacrylate, hydroxypropyl methacrylate, polypropylene glycol methacrylate, polyethylene glycol methacrylate, etc., divinylbenzene, ethylene bisacrylamide, N, N'-methylenebisacrylamide, etc. is there. Of these monomers having a vinyl group, N, N'-methylenebisacrylamide is most preferred. By using the acrylamide polymer (B-1) copolymerized with these vinyl group monomers (having a crosslinked structure), the extrusion productivity of the polyacetal resin composition is further improved, and the polyacetal resin composition is There is a tendency that the amount of formaldehyde released from the molded product obtained by use is reduced.

  Examples of the polyamide polymer (B-2) include polyamide 4,6, polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 6,10, polyamide 6,11, polyamide 6,12, polyamide 6,66, 610 terpolymer. These polyamide polymers (B-2) tend to further improve the extrusion productivity of the polyacetal resin composition when used in combination with the acrylamide polymer (B-1) described above. Among these polyamide polymers (B-2), a terpolymer of polyamide 6/66/610 having a melting point near the processing temperature of the polyacetal resin (melting point: 186 ° C.), polyamide 66 (melting point: 265 ° C.), Polyamide 6 (melting point: 230 ° C.) is preferred. The most preferable polyamide polymer (B-2) is a polyamide 6/66/610 terpolymer (melting point: 186 ° C.).

  The polyacetal resin homopolymer (A), the acrylamide polymer (B-1) and the polyamide polymer (B-2) are added and blended at the same time to adjust the powder mixture (X). Extrusion productivity tends to be further improved.

  When the nitrogen-containing compound (B) having formaldehyde scavenging ability is a mixture containing the acrylamide polymer (B-1) and the polyamide polymer (B-2), the acrylamide polymer (B-1) and the polyamide polymer ( The composition ratio with B-2) is not particularly limited, but preferably 1 to 50 parts by mass of the polyamide polymer (B-2) with respect to 100 parts by mass of the acrylamide polymer (B-1). Range. Among them, the polyamide polymer (B-2) is more preferably in the range of 1 to 30 parts by mass with respect to 100 parts by mass of the acrylamide polymer (B-1). When the composition ratio of the polyamide polymer (B-2) is out of the above range, it may be impossible to satisfy both the extrusion productivity of the polyacetal resin composition and the effect of reducing the amount of formaldehyde released at the same time.

  Next, the second group of nitrogen-containing compounds (B) having formaldehyde scavenging ability will be described.

  Examples of the hydrazide compound (B-3) include a carboxylic acid mono / or dihydrazide compound or an alkyl group-substituted mono / or dihydrazide compound synthesized by a reaction of a carboxylic acid (aromatic ring or alicyclic ring) with hydrazine. . Examples of the carboxylic acid constituting the carboxylic acid mono / or dihydrazide compound include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, Palmitic acid, margaric acid, stearic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, naphthalene Examples include acids, salicylic acid, gallic acid, mellitic acid, cinnamic acid, pyruvic acid, lactic acid, malic acid, citric acid, fumaric acid, maleic acid, aconitic acid, amino acids, and nitrocarboxylic acid. Specific examples of the carboxylic acid mono (di) hydrazide compound include carbodihydrazine, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, lauric acid dihydrazide, and malic acid. Dihydrazide, tartaric acid dihydrazide, propionic acid monohydrazide, lauric acid monohydrazide, stearic acid monohydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthalic acid dihydrazide, p-hydroxybenzoic hydrazine, p-hydroxy Benzoic hydrazine, 1,4-cyclohexanedicarboxylic acid dihydrazine, acetohydrazide, acrylohydrazide, maleic acid dihydrazide, fuma Acid dihydrazide, benzohydrazide, nicotinonitrile hydrazide, isonicotinohydrazide, isobutyl hydrazine, and hydrazide oleate.

  These hydrazide compounds (B-3) can further improve the extrusion productivity of the polyacetal resin composition when used in combination with the acrylamide polymer (B-1) described above. Among them, preferred hydrazide compounds (B-3) are adipic acid dihydrazide, sebacic acid dihydrazide, lauric acid hydrazide, lauric acid dihydrazide, stearic acid hydrazide, stearic acid dihydrazide, and most preferred hydrazide compound (B-3) is a polyacetal resin. Adipic acid dihydrazide (melting point: 172 ° C.) having a melting point in the vicinity of the processing temperature, and sebacic acid dihydrazide (melting point: 186 ° C.) are preferable.

  A polyacetal resin homopolymer (A), an acrylamide polymer (B-1), a polyamide polymer (B-2) and a hydrazide compound (B-3) are added and blended at the same time to prepare a powdery mixture (X). As a result, the extrusion productivity of the polyacetal resin composition tends to be further improved.

  Examples of the amino-substituted triazine compounds (B-4) 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, melem, melon, melam, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), Acetoguanamine (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, 2,4-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, 2-oxy-4, 6-diamino-sym-triazine, N, N, N ′, N′-tetracyanoethylbenzoguanamine, succinoguanamine, ethylene dimelamine, triguanamine, melamine cyanurate, ethylene dimelamine cyanurate, triguanamine cyanurate, ammelin, Acetoguanamine, a guanamine compound having a spiroglycol ring structure, for example, CTU guanamine (3,9-bis [2- (3,5-diamino-2,4-6-triazaphenyl) ethyl] -2,4,8 , 10-tetraoxaspiro [5,5] undecane), CMTU guanamine (3, - bis [1- (3,5-diamino-2,4,6-triazacyclononane) methyl] -2,4,8,10-spiro [5,5] undecane) and the like.

  Examples of the urea compound (B-5) include a chain urea compound and a cyclic urea compound. Examples of chain urea compounds include biurea, biuret, a condensate of urea and formaldehyde (form nitrogen), polyalkylene or arylene urea (polynonamethylene urea, etc.). Examples of cyclic urea compounds include hydantoin, 5-methylhydantoin, 5-ethylhydantoin, 5-isopropylhydantoin, 5-phenylhydantoin, 5-benzylhydantoin, 5,5-dimethylhydantoin, and 5,5-pentamethylenehydantoin. 5-methyl-5-phenylhydantoin, 5,5-diphenylhydantoin, 5- (o, m or p-hydroxyphenyl) hydantoin, 5- (o, m or p-aminophenyl) hydantoin, allantoin, 5-methyl Allantoin, metal salt of allantoin (Al salt: allantoin dihydroxyaluminum salt, etc.), clothylidene diurea, acetylene urea, mono-tetraalkoxymethyl glycoluril (mono-tetramethoxymethyl glycoluril, etc.) , (Iso) cyanuric acid, uric acid, urazole, and the like.

  Examples of the amino acid compound (B-6) include aliphatic carboxylic acid amides, cyclic carboxylic acid amides, and aromatic carboxylic acid amides. Specifically, malonamide, adipic acid amide, sebacic acid amide, dodecanedioic acid amide ε-caprolactam, benzoic acid amide, o-, m- or p-aminobenzamide, isophthalic acid diamide, terephthalic acid amide, methylenebisstearic acid Examples include amide and methylenebislauric acid amide.

  Examples of compounds belonging to the second group of nitrogen-containing compounds (B) having formaldehyde scavenging ability other than the above include guanidine compounds (B-7) and imide compounds (B-8). Examples of the guanidine compound (B-7) include cyanoguanidine and creatinine. Examples of the imide-based compound (B-8) include phthalic imide, trimellitic imide, and pyromellitic imide.

  The nitrogen-containing compound (B) having the formaldehyde scavenging ability of the first group and the second group described above includes the nitrogen-containing compound (B) having the formaldehyde scavenging ability of the first group and the nitrogen-containing compound having the formaldehyde scavenging ability of the second group. By using together with the compound (B), the extrusion productivity of the polyacetal resin composition tends to be improved, and the amount of formaldehyde released from the molded article obtained using the polyacetal resin composition tends to be remarkably reduced. It is in. Among them, a preferred combination is a combination of the first group of acrylamide polymer (B-1) and polyamide polymer (B-2) and the second group of hydrazide compound (B-3).

  The composition ratio of the first group and the second group is 10 to 100 parts by mass of the nitrogen-containing compound having the formaldehyde scavenging ability of the second group with respect to 100 parts by mass of the nitrogen-containing compound having the formaldehyde scavenging ability of the first group. It is preferable that Especially, it is more preferable that the nitrogen-containing compound which has the formaldehyde capture | capture ability of a 2nd group is 10-80 mass parts with respect to 100 mass parts of nitrogen-containing compounds which have the formaldehyde capture | capture ability of a 1st group, 10-60 mass parts More preferably, it is a part.

(Other additives (C))
In the method for producing a polyacetal resin composition according to this embodiment, it is preferable to use various conventionally known additives (C) other than the nitrogen-containing compound (B) having a formaldehyde scavenging ability.

  Examples of additives (C) include weather resistance (light) stabilizers such as antioxidants, ultraviolet absorbers and light stabilizers, plasticizers such as polyethylene glycol, olefin compounds, fatty acids, fatty acid ester compounds, and polyether compounds. Release agents, stabilizers such as fatty acid metal salts and metal hydroxide salts, antistatic agents, calcium carbonate, talc, glass fibers, carbon fibers, glass beads, and other inorganic or organic reinforcing materials. . It is also possible to add inorganic or organic pigments.

  The method for adding these various additives (C) is not particularly limited, but as described above, when the powdery mixture (X) in Step 1 is produced, the polyacetal resin homopolymer (A) and formaldehyde trapping are used. It is particularly preferable to add the other additive (C) together with the nitrogen-containing compound (B) having the ability. When manufacturing the powdery mixture (X) in the said process 1, it exists in the tendency which the extrusion productivity of a polyacetal resin composition improves more notably by adding said various additives (C). Further, the amount of formaldehyde released from a molded product obtained using the polyacetal resin composition tends to be significantly reduced.

  The additive (C) used in Step 1 above preferably contains an antioxidant and a weathering (light) stabilizer, and further preferably contains a release agent. Moreover, the additive (C) used at the said process 1 may contain the plasticizer further.

  As will be described later, when the powdery mixture (S) in Step 2 is produced, other additives (C) may be added together with the polyacetal resin homopolymer (A) and the powdery mixture (X). Good. Hereinafter, the other additive (C) will be described in detail.

  Specific examples of the antioxidant include 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-tert-butyl-4-hydroxyphenyl) -propionate), 1,4-butanediol-bis- (3- (3,5-di-tert-butyl-4-hydroxy Phenyl) -propionate), triethylene glycol-bis- (3- (3-tert-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) priionylhexamethylenediamine, 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′-salicylidenehydrazine, 3- (N-salicyloyl) And mino-1,2,4-triazole, N, N′-bis (2- (3- (3,5-di-butyl-4-hydroxyphenyl) propionyloxy) ethyl) oxyamide, and the like. Among the 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, and these antioxidants may be used singly or in combination of two or more.

  Examples of the weather resistance (light) stabilizer include benzotriazole-based ultraviolet absorbers, oxalic anilide-based ultraviolet absorbers, and hindered amine-based light stabilizers.

  Specific examples of the benzotriazole ultraviolet absorber 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-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3,5-di-t-butyl- Phenyl) benzotriazole. These benzotriazole-based ultraviolet absorbers may be used alone or in combination of two or more.

  Specific examples of the oxalic acid anilide-based ultraviolet absorber include 2-ethoxy-2′-ethyloxalic acid bisanilide, 2-ethoxy-5-tert-butyl-2′-ethyloxalic acid bisanilide, 2 -Ethoxy-3'-dodecyl oxalic acid bisanilide and the like. These oxalic anilide ultraviolet absorbers may be used alone or in combination of two or more.

  Specific examples of the hindered amine light stabilizer 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- (ethyl Carbamoyloxy) -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) 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-tricarboxylate, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- (2,4 , 8,10-Tetraoxaspir Condensate with [5,5] undecane) -diethanol, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, 1,2,3 , 4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and tridecyl alcohol.

  These hindered amine light stabilizers may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the weather resistance (light) stabilizer, the benzotriazole ultraviolet absorber, oxalic anilide ultraviolet absorber and hindered amine light stabilizer are preferably used in combination.

  Examples of the plasticizer include polyalkylene glycol plasticizers. For example, a polycondensate having alkylene glycol as a monomer. Specific examples include polyethylene glycol, polypropylene glycol, and polyethylene glycol-polypropylene glycol block polymer. The polyaddition mole number of the polyalkylene glycol is 5 to 1000.

  Other polyoxyalkylene glycol plasticizers include polyethylene glycol oleyl ether (5 to 50 ethylene oxide polymerization mole), polyethylene glycol cetyl ether (5 to 20 ethylene oxide polymerization mole), polyethylene glycol stearyl ether (ethylene oxide polymerization). 5-30 mol), polyethylene glycol lauryl ether (ethylene oxide polymerization mol number 5-30), polyethylene glycol tridecyl ether (ethylene oxide polymerization mol number 5-30), polyethylene glycol nonylphenyl ether (ethylene oxide polymerization mol number 2) ~ 100), polyethylene glycol octylphenyl ether (4 to 50 moles of ethylene oxide polymerization) can be added and mixed.

  These plasticizers may be used alone or in combination of two or more.

  Examples of the release agent include ester release agents of alcohol and fatty acid, ester release agents of alcohol and dicarboxylic acid, ester release agents of (poly) alkylene glycol and fatty acid, fatty acid amide, average polymerization degree Can include olefin compounds in which is 10 to 500.

  As the alcohol constituting the ester release agent, a monohydric alcohol or a polyhydric alcohol can be used.

  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, Examples include oleyl alcohol, nonadecyl alcohol, eicosyl alcohol, pehenyl alcohol, ceryl alcohol, melyl alcohol, 2-hexyldecanol, 2-octyldodecanol, 2-decyltetradecanol, and unilin alcohol.

  The polyhydric alcohol is preferably 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, diglycerin, triglycerin, threitol, erythritol, pentaerythritol, arabitol, ribitol, xylitol, sorbite, sorbitan, sorbitol, mannitol.

  The fatty acids constituting the ester release agent include capric acid, lauric acid, myristic acid, palmitic acid stearic acid, 12-hydroxystearic acid, alginate, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, Celluloplastic acid, undecylenic acid, oleic acid, elaidic acid, celetic acid, erucic acid, brassic acid, sorbic acid linoleic acid, linolenic acid, arachidonic acid, propiolic acid, stearolic acid and naturally occurring compounds containing such components Fatty acids or mixtures thereof are mentioned.

  Dicarboxylic acids constituting the ester release agents include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, brassic acid, maleic acid, fumaric acid. Acid, glutaconic acid and the like.

  The above fatty acids may be substituted with hydroxy groups. Among the ester-based mold release agents composed of these alcohols and fatty acids, polyhydric alcohols selected from fatty acids selected from palmitic acid, stearic acid, behenic acid, and montanic acid, and glycerin, pentaerythritol, sorbitan, and sorbitol Fatty acid esters derived from are preferred.

  Specific examples of fatty acid esters include glycerol monopalmitate, glycerol dipalmitate, glycerol tripalmitate, glycerol monostearate, glycerol distearate, glycerol tristearate, glycerol monobehenate, glycerol dibehenate, glycerol tribethenate. Behenate, glycerin monomontanate, glycerin dimontanate, glycerin trimontanate, pentaerythritol monopalmitate, pentaerythritol dipalmitate, pentaerythritol tripalmitate, pentaerythritol tetrapalmitate, pentaerythritol monostearate, penta Erythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate, pentae Lithritol 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 dipalmitate Sorbitol tripalmitate, sorbitol monostearate, sorbitol distearate, sorbitol tristearate, sorbitol monobehenate, sorbitol dibehenate, sorbitol tribehenate sorbitol monomontanate, sorbitol dimontanate, sorbitol trimontanate , Polyethylene glycol stearate, polyethylene glycol laurate, polyethylene glycol palmitate, polyethylene glycol behenate, ethylene glycol stearate, ethylene glycol laurate, ethylene glycol palmitate, ethylene glycol behenate Etc. Moreover, boric acid ester of glycerol monofatty acid ester is also mentioned as the aliphatic ester whose hydroxyl group is blocked with boric acid or the like.

  The fatty acid amide is preferably an aliphatic amide compound comprising a fatty acid having 16 or more carbon atoms and an amine or diamine.

  The fatty acids that make up these aliphatic amides are palmitic acid, isopalmitic acid, stearic acid, isostearic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, lacteric acid, celetic acid, erucic acid It is. The amine and diamine constituting the aliphatic amide are ammonia, ethylenediamine and the like. Specific examples of the aliphatic amide compound include stearyl amide, palmityl amide, oleyl amide, methylene bis stearamide, ethylene bis stearamide, ethylene bis oleyl amide, and the like.

  The olefinic compound is preferably an olefin compound having a structural unit represented by the following general formula (III) and having an average degree of polymerization of 10 to 500.

In the general formula (III), R ¹ and R ² are any one selected from the group consisting of hydrogen, an alkyl group, an aryl group, and an ether group, and may be the same or different. n is preferably an average degree of polymerization of 10 to 500.

  The alkyl group in the above formula (III) is ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, lauryl group, cetyl group, stearyl group and the like.

  Examples of the aryl group include phenyl group, p-butylphenyl group, p-octylphenyl group, p-nonylphenyl group, benzyl group, p-butylbenzyl group, tolyl group, xylyl group and the like.

  Moreover, as an ether group, an ethyl ether group, a propyl ether group, a butyl ether group etc. are mentioned, for example.

  Examples of monomers constituting these olefinic compounds include ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, 2-methyl-1-butene, and 3-methyl-1-butene. Olefin monomers represented by 2-methyl-2-butene, 1-hexene, 2,3-dimethyl-2-butene, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. 1,2-butadiene, 1,3-butadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, cyclopentadiene, and other diolefin monomers.

  The above releasing agents may be used alone or in combination of two or more.

  Examples of the stabilizer include fatty acid metal salts.

  Examples of fatty acids constituting the fatty acid metal salt include capric acid, lauric acid, myristic acid, palmitic acid stearic acid, 12-hydroxystearic acid, alginic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, celloplastic acid , Undecylenic acid, oleic acid, elaidic acid, celetic acid, erucic acid, brassic acid, sorbic acid linoleic acid, linolenic acid, arachidonic acid, propiolic acid, stearolic acid and naturally occurring fatty acids comprising such ingredients or These mixtures are mentioned. Also, dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, brassic acid, maleic acid, fumaric acid, glutaconic acid, etc. . Specific fatty acid metal salts include zinc stearate, calcium stearate, magnesium stearate and the like.

  These stabilizers may be used individually by 1 type, and may be used in combination of 2 or more type.

<Process 2>
Step 2 is a step of obtaining the powder mixture (S) by further mixing the polyacetal resin homopolymer (A) with the powder mixture (X) obtained in Step 1 above.

  The mixing ratio of the polyacetal resin homopolymer (A) and the powdery mixture (X) in the above Step 2 is such that the powdery mixture (X) is 0.1 to 10 with respect to 100 parts by mass of the polyacetal resin homopolymer (A). It is preferable that it is a mass part, It is more preferable that it is 0.1-5 mass part, It is further more preferable that it is 0.1-3 mass part.

  Moreover, in the said process 2, you may add another additive (C). It is preferable that the addition amount of the additive (C) in the said process 2 is 0.01-5 mass parts with respect to 100 mass parts of polyacetal resin homopolymer (A), and is 0.01-3 mass parts. More preferably, it is 0.1-3 mass parts.

  In the powdery mixture (X) obtained in the above step 1, since the nitrogen-containing compound (B) having a formaldehyde scavenging ability is once uniformly dispersed in the polyacetal resin homopolymer (A), this powdery mixture (X) Even when diluted with a polyacetal resin homopolymer (A), aggregation of nitrogen-containing compounds (B) having formaldehyde scavenging ability does not occur. Therefore, the type of the mixer used in the step 2 is not particularly limited, such as a Henschel mixer and a cone blender that are conventionally used.

  However, it is preferable to adjust the temperature and pressure state at the time of mixing in the above step 2 in the same manner as in the above step 1.

  The temperature at the time of mixing in Step 2 is preferably 25 to 70 ° C, more preferably 25 to 50, and further preferably 25 to 50 ° C. When the temperature at the time of mixing in the above step 2 is within the above range, aggregation of nitrogen-containing compounds (B) due to an increase in heat of mixing can be suppressed. As a result, the formaldehyde emission amount released from the finally obtained molded product tends to be reduced to a sufficiently satisfactory level, which is preferable.

  The pressure during mixing in Step 2 is preferably 1 to 70 kPa, more preferably 1 to 60 kPa, and further preferably 1 to 50 kPa. Adjustment of the pressure is usually performed using nitrogen gas. Specifically, the pressure at the time of mixing is adjusted to be within the above range by introducing nitrogen gas into the stirring mixer.

  In the step 2, when stirring and mixing, the stirring and mixing time is preferably 10 seconds to 1 hour, more preferably 1 minute to 1 hour, and further preferably 2 minutes to 1 hour.

  Especially, it is preferable to adjust the product temperature in a stirring mixer at 25-70 degreeC and the range of 1-70 kPa. The stirring and mixing time is preferably adjusted in the range of 10 seconds to 1 hour so that the product temperature is in the range of 25 to 70 ° C.

<Step 3>
Step 3 is a step of melt-kneading the powdery mixture (S) obtained in Step 2 above.

  The melt kneading method in the above step 3 may be an ordinary melt kneading method, for example, a single or biaxial extruder, and is not particularly limited, but is preferably an extruder during melt kneading. It is preferable to devolatilize under reduced pressure from the vent part.

  The temperature at the time of melt kneading in Step 3 is preferably the melting point of the polyacetal resin homopolymer (A) to 250 ° C, more preferably the melting point of the polyacetal resin homopolymer (A) + 10 ° C to 240 ° C. The melting point of the polyacetal resin homopolymer (A) is more preferably 10 ° C to 230 ° C.

  The pressure at the time of melt kneading in Step 3 is preferably −500 to −760 mmHg, more preferably −600 to −760 mmHg, and still more preferably −650 to −760 mmHg.

  The polyacetal resin composition according to the present embodiment is obtained by a production method including the steps 1 to 3 described above.

  Moreover, if the polyacetal resin composition which concerns on this embodiment is used, the molded article with few formaldehyde discharge | release amounts can be stably manufactured efficiently for a long period of time. The molded article can be suitably used for mechanical parts such as automobile parts, electric / electronic parts and industrial parts.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the Example mentioned later.

<Methods for measuring raw materials and various physical properties in Examples and Comparative Examples>
[1] Polyacetal resin homopolymer (A)
The terminal-stabilized polyacetal resin homopolymer was pulverized under the following pulverization conditions (a) to obtain polyacetal resin homopolymers (A) (A-1 to A-5) shown in Table 1 below.

(A) Grinding conditions Crusher: Rotary crusher manufactured by Nara Machinery Co., Ltd. (model: M1)
2. Rotation speed: 1200rpm
3. Screen mesh: 20 mesh The MFR value and particle size of the polyacetal resin homopolymer (A) were measured according to the methods described in [2] and [3] below.

[2] Method for measuring MFR value of polyacetal resin homopolymer (A) According to ASTM D1238, MFR value was measured under the conditions of a temperature of 190 ° C. and a load of 2.16 kg using MELT INDEXER manufactured by Toyo Seiki Co., Ltd.

[3] Method of measuring particle diameter of polyacetal resin homopolymer (A) The particle diameter of polyacetal resin homopolymer (A) is placed on a sieve having openings of 500 μm, 250 μm, and 100 μm, and the following a sieve device is used. Each mass was measured.

・ Sieving device: Micro-type electromagnetic vibration sieve device (model: M-100 type) manufactured by Tsutsui Rikenki Co., Ltd.
-Sieve vibration time: 15 minutes [4] Nitrogen-containing compound having formaldehyde scavenging ability (B)
・ Acrylamide polymer (B-1-1 to B-1-4)
Using zirconium tetraisopropoxide as a catalyst, acrylamide and methylenebisacrylamide were reacted, and the resulting acrylamide polymer was pulverized with a jet mill pulverizer to obtain an acrylamide polymer (B-1-1) shown in Table 2 below. ) To (B-1-4) were obtained.

-Acrylamide polymer (B-1-5)
Except not using methylene bisacrylamide, operation similar to said B-1-1 was performed and the acrylamide polymer (B-1-5) of the following table 2 was obtained.

  In addition, the average particle diameter, primary amide group content, and reduced viscosity of the obtained acrylamide polymers (B-1-1) to (B-1-5) are as described in [5] to [7] below. It was measured by the method described.

・ Polyamide polymer (B-2)
B-2-1: Terpolymer of polyamide 6/66/610 (manufactured by Asahi Kasei Corporation, product: NA900) (melting point: 186 ° C.)
・ Hydrazide compound (B-3)
B-3-1: Sebacic acid dihydrazide (manufactured by Nippon Finechem) (melting point: 186 ° C.)
B-3-2: Adipic acid dihydrazide (manufactured by Nippon Finechem) (melting point: 172 ° C.)
Amino-substituted triazine compounds (B-4)
B-4-1: 3,9-bis [2- (3,5-diamino-2,4-6-triazaphenyl) ethyl] -2,4,8,10-tetraoxaspiro [5,5 ] Undecane (manufactured by Ajinomoto Co., Inc.) (CTU guanamine: average particle size ≈ 2.9 μm)
・ Urea compound (B-5)
・ B-5-1: 5, 5'-dimethylhydantoin (made in China)
・ Amino acid compound (B-6)
・ B-6-1: Methylenebisstearic acid amide (manufactured by NOF Corporation)
・ Additives other than nitrogen-containing compounds with formaldehyde scavenging ability (C)
C-1: Triethylene glycol-bis- (3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate) (manufactured by Ciba Specialty Chemicals)
C-2: 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9 -(2,4,8,10-tetraoxaspiro [5,5] undecane) -condensation product with diethanol (manufactured by ADEKA)
C-3: ethylene glycol stearate (manufactured by NOF Corporation)
C-4: Polyethylene glycol (manufactured by NOF Corporation) (molecular weight: 6000)
[5] Method for measuring average particle size of acrylamide polymer (B-1) 0.03 g of acrylamide polymer is dispersed in ethanol (manufactured by Wako Pure Chemical Industries, Ltd., reagent special grade), and the average particle size is measured with the following apparatus. Carried out.

-Particle size measuring device: SALD-2000 manufactured by Shimadzu Corporation
[6] Method for measuring primary amide group content of acrylamide polymer (B-1) Into a flask equipped with a stirrer, an acrylamide polymer and a 40% by mass aqueous potassium hydroxide solution are added and stirred at 105 to 110 ° C. Heated for 20 minutes to hydrolyze the primary amide group with ammonia. Next, the flask contents were cooled to 50 ° C. or lower, methanol was added, and ammonia was extracted together with methanol.

  This extract was absorbed in a 0.1 N aqueous sulfuric acid solution, neutralized with a 0.1 N aqueous sodium hydroxide solution using methyl red as an indicator, and the primary amide group was quantified.

[7] Method for measuring reduced viscosity of acrylamide polymer (B-1) To 50 mL of formic acid (special grade reagent), 0.50 g of acrylamide polymer (B) was added and stirred for 2 hours. Thereafter, the drop speed (t1) was measured using an Ostwald viscometer in a thermostatic bath, and the reduced viscosity was measured from the time difference between the blank value (no acrylamide polymer) and the drop speed (t0). The temperature of the thermostatic chamber was 35 ° C. ± 1 ° C. As the viscosity solvent, formic acid was used.

[8] Formaldehyde emission amount 1% of the polyacetal resin composition was placed in a molding product (test piece I) obtained by injection molding of the polyacetal resin composition under the molding conditions (a) below and a molding machine under the molding conditions (a) below. The molded article (test piece II) obtained by holding for a period of time and injection molding after the residence for 1 hour was left in a thermostatic chamber set at 23 ° C. and a humidity of 50% for 24 hours. Thereafter, the amount of formaldehyde released from each test piece was measured in accordance with the formaldehyde emission amount measurement conditions of (b) below.

(A) Molding conditions-Injection molding machine: Toshiba Machine Co., Ltd. [IS100GN]
・ Cylinder setting temperature: 210 ℃
・ Mold temperature: 90 ℃
Molding cycle: injection / cooling = 20 seconds / 10 seconds Molded product size: 10 cm × 4 cm × 0.3 cm
(B) Measurement of formaldehyde emission amount The two molded products, the molded product after staying in the molding machine and the non-residual molded product, were hung in a container containing 50 cc of pure water. The container was sealed. This sealed container was placed in an oven set at 60 ° C. and left for 3 hours. Then, it cooled with air and the amount of extracted formaldehyde was quantified by the acetylacetone method.

[Examples 1-33]
(1) Preparation of powdery mixture (X) The composition ratio of polyacetal resin homopolymer (A), nitrogen-containing compound (B) having formaldehyde scavenging ability and other additives (C) is as shown in Table 3 below. Prepared raw materials (Y-1 to Y-23) were prepared.

The stirring and mixing conditions (Z-1 to Z-11) used in the examples are shown in Table 4 below. In addition, the manufacturer and model of the stirring mixer used are as follows.

-Planetary motion mixing machine: SV mixer manufactured by Shinko Faudler Co., Ltd.-Henschel mixing machine: FM75C manufactured by Mitsui Miike Manufacturing Co., Ltd.

The powdery mixture raw materials (Y-1 to Y-23) were mixed under the mixing conditions (Z-1 to Z-11) as shown in Table 5 below to obtain a powdery mixture (X).

(2) Preparation of powdery mixture (S) In the composition ratio as shown in Table 6, the powdery mixture (X) obtained in (1) above, polyacetal resin homopolymer (A) and other additives (C ) And mixed with a Henschel mixer to obtain a powdery mixture (S). The stirring and mixing conditions were such that the temperature was 35 ° C., the pressure was 10 kPa with nitrogen, the rotation speed of the stirring blade was 100 rpm, and the stirring time was 120 seconds.

(3) Extrusion production of polyacetal resin composition The powdery mixture (S) obtained in (2) above was subjected to the following conditions (L / D = 32) using a TEX30φ vented twin-screw extruder (L / D = 32) Extruded in a) to obtain a polyacetal resin composition. Moreover, extrusion productivity of the polyacetal resin composition was determined as shown in (b) below.

(A) Extrusion conditions Resin temperature: 210 ° C
Screw rotation speed: 60rpm
Discharge rate: 10 kg / hr
Vent pressure: -700 mmHg reduced pressure (b) Extrusion productivity determination The extrusion production of the polyacetal resin composition was started with the above extruder, and then 5 kg of pellets of the polyacetal resin composition obtained every 1 hour were taken out in this pellet. The number of carbides and denatured substances mixed in was measured with a foreign substance inspection machine (PDI-III type manufactured by Hubren Co., Ltd.). Based on the obtained results, extrusion productivity was determined.

  The extrusion productivity of the polyacetal resin composition was determined based on the following criteria based on the extrusion time when the number of foreign matters reached 20.

(Standard)
19 hours or more: good
Less than 19 hours: Poor (4) Measurement of the amount of formaldehyde released from the molded product The polyacetal resin composition after 5 hours from the start of extrusion in (3) above is withdrawn, and the amount of formaldehyde released from the molded product by the method described in [8] above. Was measured. The results are shown in Table 6.

[Comparative Example 1]
100 parts by mass of polyacetal resin homopolymer (A-3), 0.1 part by mass of nitrogen-containing compound (B-1) having formaldehyde scavenging ability and 0.1 part by mass of antioxidant (C-1) were mixed with Henschel. The mixture was obtained by mixing with a machine. The stirring and mixing conditions were such that the rotation speed of the stirring blade was 100 rpm and the stirring and mixing time was 120 seconds.

  Except having used the obtained mixture, it carried out similarly to the above-mentioned Examples 1-33 (3), produced the polyacetal resin composition, and evaluated extrusion productivity of this polyacetal resin composition. Moreover, the polyacetal resin composition 5 hours after the extrusion start was extracted, and the amount of formaldehyde released from the molded product was measured by the method shown in [8] above. The results are shown in Table 6.

[Comparative Example 2]
A mixture was obtained in the same manner as in Comparative Example 1 except that 0.01 parts by mass of the polyamide polymer (B-2) was added to the composition of Comparative Example 1. Except having used this mixture, the polyacetal resin composition was produced similarly to (3) in the above Examples 1-33, and extrusion productivity of the polyacetal resin composition was evaluated. Moreover, the polyacetal resin composition 5 hours after the extrusion start was extracted, and the amount of formaldehyde released from the molded product was measured by the method shown in [8] above. The results are shown in Table 6.

[Comparative Example 3]
The powdery mixture (X-1) prepared in Example 1 was melted with a TEX30φ vented twin screw extruder (L / D = 32) manufactured by Nippon Steel Works under the conditions of a cylinder temperature of 200 ° C. and a screw rotation speed of 50 rpm. Kneaded. The obtained molten mixture (resin pellet) was added to 0.3 parts by mass with respect to 100 parts by mass of the polyacetal resin homopolymer (A-1) and mixed with a Henschel mixer to obtain a mixture. The stirring and mixing conditions were such that the temperature was 35 ° C., the pressure was atmospheric pressure, the rotation speed of the stirring blade was 100 rpm, and the stirring and mixing time was 120 seconds.

  Except having used the obtained mixture, it carried out similarly to the above-mentioned Examples 1-33 (3), produced the polyacetal resin composition, and evaluated extrusion productivity of this polyacetal resin composition. Moreover, the polyacetal resin composition 5 hours after the extrusion start was extracted, and the amount of formaldehyde released from the molded product was measured by the method shown in [8] above.

As is clear from the evaluation results in Table 6, according to Examples 1 to 33, even when the polyacetal resin composition is continuously extruded for a long time, the polyacetal resin is thermally decomposed and modified such as various additives. It was found that can be effectively suppressed. Moreover, it turned out that the molded article produced using these polyacetal resin compositions can reduce formaldehyde emission amount remarkably.

  In addition, Table 7 shows the composition ratio of each component of the obtained polyacetal resin composition.

  The polyacetal resin composition obtained by the production method of the present invention and a molded body using the same have industrial applicability as electrical, electronic equipment parts, automobile mechanism parts, industrial mechanism parts, and the like.

Claims (9)

Step 1 of mixing a polyacetal resin homopolymer (A) and a nitrogen-containing compound (B) having formaldehyde scavenging ability in a powder state to obtain a powdery mixture (X);
Step 2 of further obtaining a powdery mixture (S) by further mixing the polyacetal resin homopolymer (A) with the obtained powdery mixture (X);
And a step 3 of melt-kneading the obtained powdery mixture (S). A method for producing a polyacetal resin composition, comprising:   The method for producing a polyacetal resin composition according to claim 1, wherein the mixing in the step 1 is performed at a pressure of 1 to 100 kPa and a temperature of 25 to 70 ° C.   The polyacetal resin according to claim 1 or 2, wherein the addition amount of the nitrogen-containing compound (B) in the step 1 is 10 to 1000 parts by mass with respect to 100 parts by mass of the polyacetal resin homopolymer (A). A method for producing the composition.   The method for producing a polyacetal resin composition according to any one of claims 1 to 3, wherein the mixing in the step 1 is performed with a planetary motion type stirring mixer.   The polyacetal resin homopolymer (A) is a particle having a particle diameter of 500 μm or less, and the ratio of particles having a particle diameter of 100 to 250 μm in the polyacetal resin homopolymer (A) is 30% by mass or more. Item 5. A method for producing a polyacetal resin composition according to any one of Items 1 to 4.   The method for producing a polyacetal resin composition according to any one of claims 1 to 5, wherein the nitrogen-containing compound (B) in the step 1 is an acrylamide polymer (B-1).   The polyacetal according to any one of claims 1 to 5, wherein the nitrogen-containing compound (B) in the step 1 is a mixture of an acrylamide polymer (B-1) and a hydrazide compound (B-3). A method for producing a resin composition. The method for producing a polyacetal resin composition according to claim 6 or 7, wherein the acrylamide polymer (B-1) includes a structure represented by the following general formula (I) and / or the following general formula (II). .
  The polyacetal resin composition obtained by the manufacturing method of the polyacetal resin composition of any one of Claims 1-8.