JP5616102B2 - Automotive interior / mechanical parts - Google Patents

Description

  The present invention relates to automobile interior / mechanical parts.

  The polyacetal resin has high mechanical strength and rigidity, is excellent in oil resistance and organic solvent resistance, is well balanced in a wide temperature range, and is easy to process. Therefore, polyacetal resin is often used as representative engineering plastics in OA equipment, digital home appliances, automobile parts, and other industrial parts.

  However, when polyacetal resin is used in automobile interior parts and mechanical parts (hereinafter also referred to as “automobile interior / mechanical parts”), formaldehyde is generated in the automobile interior. In recent years, voluntary regulations by automakers and auto parts suppliers have increasingly demanded suppression of formaldehyde generation in automobile cabins.

  In order to meet this demand for the suppression of formaldehyde generation, a method of adding guanamine and a hydrazide compound to a polyacetal resin (see, for example, Patent Documents 1 and 5), a method of adding a carboxylic acid hydrazide compound (for example, Patent Documents 2, 3 and 4), a method of adding a hydrazide compound (for example, see Patent Documents 6 and 7), and a method of adding an aromatic dihydrazide and an aliphatic hydrazide compound (for example, see Patent Document 8).

JP 2008-7676 A JP-A-4-345648 JP-A-10-298401 JP 2007-91973 A JP 2007-51205 A JP 2006-306944 A JP 2006-45489 A JP 2005-325225 A

  However, the addition of these compounds that suppress the generation of formaldehyde (generally also referred to as “form catcher”) affects the crystallization status of the polyacetal resin. And in shaping | molding of a polyacetal resin composition, there exists room for improvement in the mold deposit-proof property on the conditions with a low filling rate to a metal mold | die. Mold deposit (hereinafter also referred to as “MD”) refers to a contaminant attached to a mold during molding. When the adhesion of MD proceeds, the surface appearance of the obtained molded product is deteriorated or the releasability is deteriorated.

  In the manufacture of automobile interior / mechanical parts using a polyacetal resin composition, the molding size may increase or a multi-cavity mold may be used. Particularly in such a case, when the fluidity of the polyacetal resin composition is lowered, the filling rate of the polyacetal resin composition into the mold is likely to be lowered, and the adhesion of MD in the mold is likely to proceed. As a result, there is a problem that the mold must be frequently cleaned, and the productivity of automobile interior and mechanism parts is significantly reduced.

  Furthermore, automobile interior / mechanism parts are often used under high temperature stress for a long period of time, or are repeatedly subjected to stress. There is a problem that the amount of formaldehyde generated from automobile interior and mechanism parts under such conditions cannot be stably suppressed.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a raw material composition containing a polyacetal resin, a hydrazine derivative, and a compound that lowers the melting point of the hydrazine derivative. It has been found that an automobile interior / mechanical part obtained by using a polyacetal resin composition having a maximum endothermic peak temperature in a DSC curve satisfying a specific condition and having a melt flow rate of 2 to 10 g / 10 minutes can solve the above problems. The present invention has been completed.

  That is, the present invention relates to the following.

[1]
Obtained from a raw material composition containing a polyacetal resin (A), a hydrazine derivative (B), and a compound (C) that lowers the melting point of the hydrazine derivative (B), the following conditional expressions (1) and (2) Automotive interior / mechanical parts obtained using a polyacetal resin composition satisfying the above and having a melt flow rate of 2 to 10 g / 10 min.

T1 <T2 (1)
T1 <T3 (2)
(In the formulas (1) and (2),
T1 is obtained by sequentially performing the following operations (I) to (III) on the mixture of the hydrazine derivative (B) and the compound (C) using a differential scanning calorimeter, and then the mixture melts. Among the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until, the temperature (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity,
T2 is 2.5 until the hydrazine derivative (B) melts after sequentially performing the following operations (I) to (III) on the hydrazine derivative (B) using a differential scanning calorimeter. Among the endothermic peaks obtained when the temperature is raised at a rate of ° C./min, the endothermic peak having the highest endothermic capacity is the temperature (° C.).
T3 is 2.5 until the polyacetal resin (A) is melted after the following operations (I) to (III) are sequentially performed on the polyacetal resin (A) using a differential scanning calorimeter. Of the endothermic peaks obtained when the temperature is raised at a rate of ° C./minute, this is the temperature (° C.) indicating the apex of the endothermic peak having the largest endothermic capacity.
(I) The temperature is raised at a rate of 320 ° C./min from a temperature lower than the first endothermic peak of the measurement target component to a temperature at which the measurement target component melts.
(II) Hold at the temperature at which the component to be measured is melted for 2 minutes.
(III) The temperature is lowered to 100 ° C. at a rate of 10 ° C./min. )
[2]
The automobile interior / mechanism part according to [1], wherein the melt flow rate is 2 to 5 g / 10 min.

[3]
The automobile interior / mechanism part according to [1] or [2], wherein the automobile interior / mechanism part is at least one selected from the group consisting of a door, a sunroof, a seat belt, a switch, a clip, a seat, and a wiper.

[4]
The automobile interior / mechanical component according to any one of [1] to [3], wherein the amount of formaldehyde generated calculated by VDA275 is 2 mg / kg or less.

[5]
The automobile interior / mechanism part according to any one of [1] to [4], wherein the amount of formaldehyde generated calculated by VDA275 is 1 mg / kg or less.

[6]
The automobile interior / mechanism part according to any one of [1] to [5], wherein the compound (C) is a hydrazine derivative different from the hydrazine derivative (B).

[7]
The hydrazine derivative (B) is a carboxylic acid hydrazide;
The automobile interior / mechanism part according to any one of [1] to [6], wherein the compound (C) is a carboxylic hydrazide different from the hydrazine derivative (B).

[8]
The hydrazine derivative (B) is a carboxylic acid dihydrazide represented by the following general formula (i):
The automobile interior / mechanism part according to any one of [1] to [7], wherein the compound (C) is a carboxylic hydrazide different from the hydrazine derivative (B).

(In formula (i), R ₁ represents a divalent substituted or unsubstituted hydrocarbon group.)
[9]
The automobile interior according to any one of [1] to [8], wherein the hydrazine derivative (B) is at least one carboxylic acid dihydrazide selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide.・ Mechanical parts.

[10]
The hydrazine derivative (B) is at least one carboxylic acid dihydrazide (b) selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide and dodecanedioic acid dihydrazide;
The compound (C) is at least one carboxylic acid dihydrazide (c) selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide and dodecanedioic acid dihydrazide (provided that the carboxylic acid dihydrazide (b) and the carboxylic acid The vehicle interior / mechanical component according to any one of [1] to [9], which is different from the acid dihydrazide (c).

[11]
[1] to [10] in which the total content of the hydrazine derivative (B) and the compound (C) is 0.03 to 0.2 parts by mass with respect to 100 parts by mass of the polyacetal resin (A). Automotive interior / mechanical parts as described in any of the above.

[12]
The automobile according to any one of [1] to [11], wherein a mass ratio ((B) :( C)) between the hydrazine derivative (B) and the compound (C) is 2: 8 to 8: 2. Interior / mechanical parts.

[13]
The automobile according to any one of [1] to [12], wherein a mass ratio ((B) :( C)) between the hydrazine derivative (B) and the compound (C) is 3: 7 to 7: 3. Interior / mechanical parts.

[14]
The automobile interior / mechanism component according to any one of [1] to [13], wherein the polyacetal resin (A) is a polyacetal copolymer.

[15]
The automobile interior / mechanism component according to any one of [1] to [14], wherein the polyacetal resin (A) is a polyacetal copolymer obtained using methylal as a chain transfer agent.

  According to the present invention, in the production of automobile interior and mechanism parts using a polyacetal resin composition, even when the molding size is increased or a multi-cavity mold is used, mold deposits are generated in the mold. Can be suppressed. In addition, according to the present invention, it is possible to provide an automobile interior / mechanism component that stably generates a small amount of formaldehyde even when it is used while being stressed for a long time at a high temperature, or when it is subjected to repeated stress.

It is a chart which shows the result of differential scanning calorimetry of adipic acid dihydrazide. It is a chart which shows the result of differential scanning calorimetry of sebacic acid dihydrazide. It is a chart which shows the result of the differential scanning calorimetry of the mixture of adipic acid dihydrazide and sebacic acid dihydrazide. It is a chart which shows the result of the differential scanning calorimetry of the mixture of sebacic acid dihydrazide and isophthalic acid dihydrazide. It is a schematic diagram of the test piece for bending fatigue characteristics (ASTM D671 TYPEI test piece). It is a schematic diagram of a tensile creep characteristic test piece (JIS No. 2 improved type). It is a figure which shows the cutting dimension at the time of the formaldehyde generation amount measurement in the test piece for bending fatigue characteristics.

  Hereinafter, a form for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. In the drawings, positional relationships such as up, down, left and right are based on the positional relationships shown in the drawings unless otherwise specified. Further, the present invention is not limited to the present embodiment described below, and can be implemented with various modifications within the scope of the gist.

≪Automobile interior / mechanical parts≫
The automobile interior / mechanism component according to the present embodiment is obtained using a specific polyacetal resin composition described later.

  The automobile interior / mechanism component is preferably at least one selected from the group consisting of a door, a sunroof, a seat belt, a switch, a clip, a seat, and a wiper.

  Further, in the automobile interior / mechanism parts, the formaldehyde generation amount calculated by VDA275 is preferably 2 mg / kg or less, and more preferably 1 mg / kg or less.

  In the present embodiment, the amount of formaldehyde generated is a value calculated by the following VDA275.

(VDA275)
First, 50 mL of distilled water and a test piece are accommodated in a polyethylene container and sealed. Next, after heating the polyethylene container at 60 ° C. for 3 hours, formaldehyde generated in distilled water is reacted with acetylacetone in the presence of ammonium ions. An absorption peak at a wavelength of 412 nm is measured for the obtained reaction product using a UV spectrometer, and the amount of formaldehyde generated (kg / kg) per kg of the test piece is calculated.

  The method for manufacturing the automobile interior / mechanism parts of the present embodiment is not particularly limited. Therefore, known molding methods such as extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, other material molding, gas assist injection molding, foam injection molding, low pressure molding, ultra-thin injection molding. Molded with a specific polyacetal resin composition to be described later by any one of molding methods such as (ultra-high-speed injection molding) and in-mold composite molding (insert molding, outsert molding), etc. to obtain automobile interior / mechanical parts be able to.

  The automobile interior / mechanism parts of the present embodiment have a balance of mechanical properties possessed by polyacetal resin. Moreover, even when the shape of a molded product becomes large or a multi-cavity die is produced during the production of automobile interiors and mechanical parts, the mold deposit resistance is excellent. In addition, the automobile interior / mechanical parts of this embodiment have a stable and low formaldehyde generation amount even when used under a high temperature for a long period of time or when a repeated stress is applied.

  Hereinafter, the polyacetal resin composition used for the automobile interior / mechanism parts of this embodiment will be described.

<Polyacetal resin composition>
The polyacetal resin composition used in the present embodiment includes a polyacetal resin (A), a hydrazine derivative (B), and a compound (C) that lowers the melting point of the hydrazine derivative (B) (hereinafter simply referred to as “compound (C)”. The maximum endothermic peak temperature in the DSC curve of the containing component satisfies a specific condition, and the melt flow rate is 2 to 10 g / 10 min.

  In the present embodiment, the “raw material composition” means a composition containing the above three components (A) to (C) which is a raw material for producing a polyacetal resin composition. The polyacetal resin composition used in the present embodiment can be obtained by subjecting the raw material composition to a treatment such as mixing, melting, and kneading. It is preferable that the polyacetal resin composition obtained by performing these treatments subsequently contains the three components (A) to (C).

  By using the polyacetal resin composition obtained from the above raw material composition, the amount of formaldehyde generated is stable and low even when it is used for a long time under high temperature or when repeated stress is applied. Parts can be obtained.

  Moreover, the polyacetal resin composition used in the present embodiment satisfies the following conditional expressions (1) and (2).

T1 <T2 (1)
T1 <T3 (2)
In the formulas (1) and (2), T1 represents a mixture of the hydrazine derivative (B) and the compound (C) using a differential scanning calorimeter (trade name “DSC7”, manufactured by Perkin Elmer). Of the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until the mixture is melted after the following operations (I) to (III) are sequentially performed, the endothermic capacity is the largest. It is the temperature (° C.) indicating the peak of the endothermic peak, and T2 is the following (I) with respect to the hydrazine derivative (B) using a differential scanning calorimeter (trade name “DSC7”, manufactured by PerkinElmer). Among the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until the hydrazine derivative (B) is melted after the operations of (III) are sequentially performed, the endothermic peak having the largest endothermic capacity. Is the temperature (° C) indicating the top of T3 was obtained by sequentially performing the following operations (I) to (III) on the polyacetal resin (A) in order using a differential scanning calorimeter (trade name “DSC7”, manufactured by PerkinElmer Co., Ltd.) Of the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until the polyacetal resin (A) melts, this is the temperature (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity.

  (I) The temperature is raised at a rate of 320 ° C./min from a temperature lower than the first endothermic peak of the measurement target component to a temperature at which the measurement target component melts.

  (II) Hold at the temperature at which the component to be measured is melted for 2 minutes.

  (III) The temperature is lowered to 100 ° C. at a rate of 10 ° C./min.

  By forming a mold using the polyacetal resin composition that satisfies the above conditional expressions (1) and (2), generation of mold deposits in the mold can be suppressed. And it exists in the tendency which can obtain the vehicle interior and mechanism components with a favorable surface external appearance. Furthermore, recycling molding tends to be easy. In particular, by using a polyacetal resin composition that satisfies the above conditional expressions (1) and (2) even in the case of automobile interior / mechanical parts manufacture, such as when the molding size is increased or a multi-cavity mold is used. The generation of mold deposits in the mold can be suppressed.

  The polyacetal resin composition satisfying the above conditional expressions (1) and (2) contains, for example, each component using a polyacetal resin (A), a hydrazine derivative (B), and a compound (C) of the kind described later. It can be obtained by appropriately adjusting the amount.

  Moreover, the polyacetal resin composition used in this embodiment has a melt flow rate of 2 to 10 g / 10 minutes, and preferably 2 to 5 g / 10 minutes.

  A polyacetal resin composition having a melt flow rate within the above range is excellent in fluidity, has a good filling rate into the mold, and can suppress the formation of mold deposits in the mold. And it exists in the tendency which can obtain the vehicle interior and mechanism components with a favorable surface external appearance. Furthermore, recycling molding tends to be easy.

  In the present embodiment, the melt flow rate is a value measured under conditions of 190 ° C. and 2169 g in accordance with ASTM-D1238.

[Polyacetal resin (A)]
As polyacetal resin (A) used for this embodiment, if it is conventionally known, it will not specifically limit, For example, a polyacetal homopolymer and a polyacetal copolymer are mentioned.

  As the polyacetal homopolymer, for example, a polyacetal homopolymer composed only of oxymethylene units obtained by homopolymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde such as a trimer (trioxane) or a tetramer (tetraoxane). Polymers. Examples of the polyacetal copolymer include formaldehyde monomers or cyclic oligomers of formaldehyde such as trimer (trioxane) or tetramer (tetraoxane), ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, and the like. Polyacetal copolymer obtained by copolymerizing cyclic ether or cyclic formal such as cyclic formal of glycol or diglycol, which is one or two or more comonomers selected from the group consisting of 1,4-butanediol formal It is done. Furthermore, as a polyacetal copolymer, a polyacetal copolymer having a branch obtained by copolymerizing a formaldehyde monomer or a cyclic oligomer of the above formaldehyde with a monofunctional glycidyl ether; a formaldehyde monomer or a cyclic oligomer of the above formaldehyde, and a polyfunctional A polyacetal copolymer having a crosslinked structure obtained by copolymerization with glycidyl ether is also exemplified.

  Further, a compound having a functional group such as a hydroxyl group at both ends or one end, for example, a polyacetal homopolymer having a block component obtained by polymerizing a formaldehyde monomer or a cyclic oligomer of formaldehyde in the presence of polyalkylene glycol; Similarly, it is obtained by copolymerizing a compound having a functional group such as a hydroxyl group at both ends or one end, such as a hydrogenated polybutadiene glycol, with a formaldehyde monomer or a cyclic oligomer of the above formaldehyde, a cyclic ether, and a cyclic formal. A polyacetal copolymer having a block component is also exemplified as the polyacetal resin (A). The said polyacetal resin (A) may be used individually by 1 type, and may be used together in combination of 2 or more type.

  As described above, any of a polyacetal homopolymer and a polyacetal copolymer can be used as the polyacetal resin (A).

  The polyacetal resin (A) used in the present embodiment is preferably a polyacetal copolymer from the viewpoint of a balance between thermal stability and mechanical properties.

  When the polyacetal resin (A) is a polyacetal copolymer of trioxane and a comonomer such as 1,3-dioxolane, generally, the copolymerization ratio of the comonomer is 0.001 to 0.6 mol with respect to 1 mol of trioxane. If it is in the range, the thermal stability becomes good, which is preferable. The copolymerization ratio of the comonomer is more preferably 0.001 to 0.2 mol, and further preferably 0.0013 to 0.1 mol.

  The polymerization catalyst used when the polyacetal copolymer is obtained by copolymerization is not particularly limited, but cationically active catalysts such as Lewis acids, proton acids and esters or anhydrides thereof are preferable.

  Examples of the Lewis acid include boric acid, tin, titanium, phosphorus, arsenic, and antimony halides, and more specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, and phosphorus pentafluoride. , Phosphorus pentachloride, antimony pentafluoride and complex compounds or salts thereof. However, the Lewis acid is not limited to these.

  Specific examples of the protonic acid, its ester or anhydride include perchloric acid, trifluoromethanesulfonic acid, perchloric acid-tertiary butyl ester, acetyl perchlorate, trimethyloxonium hexafluorophosphate, It is not limited to.

  Among these cationically active catalysts, boron trifluoride; boron trifluoride hydrate; and a coordination complex compound of an organic compound containing an oxygen atom or a sulfur atom and boron trifluoride are preferable. As such a cationically active catalyst, for example, boron trifluoride diethyl ether, boron trifluoride di-n-butyl ether, and boron trifluoride di-n-butyl etherate are preferable from the viewpoint of improving the polymerization yield.

  Moreover, when obtaining the said polyacetal copolymer, in addition to a cation active catalyst, you may use suitably polymerization chain agents (chain transfer agent), such as methylal.

  The polyacetal resin (A) used in this embodiment is preferably a polyacetal copolymer obtained using methylal as a chain transfer agent. When methylal is used as a chain transfer agent, methylal having a water content of 100 ppm or less and a methanol content of 1% by mass or less, more preferably a methylal having a water content of 50 ppm or less and a methanol content of 0.7% by mass or less. Is preferred.

  The polymerization method of the polyacetal copolymer is not particularly limited, but conventionally known methods, for example, U.S. Pat. No. 30,273,352, U.S. Pat. No. 3,803,094, German Patent No. 1161412, and German Patent Invention No. No. 1495228, German Patent No. 1720358, German Patent No. 3018898, JP-A-58-98322, JP-A-7-70267. Japanese Patent Publication No. 55-42085 proposes a trivalent phosphorus compound as a catalyst deactivator that does not need to be washed and removed. However, it is unstable to obtain a polyacetal copolymer having higher thermal stability. It is necessary to remove the ends.

The polyacetal copolymer obtained by the above polymerization has a thermally unstable terminal portion (— (OCH ₂ ) _m —OH group, where m represents the number of repeating units), so that it is practically used. In order to improve the property, it is preferable to carry out the decomposition and removal treatment of the specific unstable terminal portion shown below.

  Decomposition and removal treatment of a specific unstable terminal portion (hereinafter, also simply referred to as “unstable end portion removal treatment”) is, for example, the presence of at least one quaternary ammonium compound represented by the following general formula (A) Below, it is the method of heat-processing in the state which melted the polyacetal copolymer at the temperature more than melting | fusing point of a polyacetal copolymer and 260 degrees C or less.

[R ^a R ^b R ^c R ^d N ⁺ ] _n X ^n- (A)
Here, in formula (I), R ^a , R ^b , R ^c and R ^d are each independently a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; carbon An aralkyl group in which at least one hydrogen atom of a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms is substituted with an aryl group having 6 to 20 carbon atoms; at least one hydrogen atom of an aryl group having 6 to 20 carbon atoms is The alkylaryl group substituted by the C1-C30 substituted or unsubstituted alkyl group is shown, and a substituted or unsubstituted alkyl group is linear, branched, or cyclic. The substituent of the substituted alkyl group is a halogen atom, a hydroxyl group, an aldehyde group, a carboxyl group, an amino group, or an amide group. Further, in the above unsubstituted alkyl group, aryl group, aralkyl group, and alkylaryl group, the hydrogen atom may be substituted with a halogen atom. n shows the integer of 1-3. X represents a hydroxyl group or an acid residue of a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid other than a hydrogen halide, an oxo acid, an inorganic thioacid, or an organic thioacid having 1 to 20 carbon atoms.

The quaternary ammonium compound is not particularly limited as long as it is represented by the above general formula (A), but R ^a , R ^b , R ^c and R ^d in the general formula (A) are each independently selected. And preferably an alkyl group having 1 to 5 carbon atoms or a hydroxyalkyl group having 2 to 4 carbon atoms, and at least one of R ^a , R ^b , R ^c and R ^d is a hydroxyethyl group Is particularly preferred. Specific examples of the quaternary ammonium compounds described above include tetramethylammonium, tetoethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6-hexamethylenebis (trimethyl Ammonium), decamethylene-bis- (trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl (2-hydroxyethyl) Ammonium, tri-n-butyl (2-hydroxyethyl) ammonium, trimethylbenzylammonium, triethylbenzylammonium, tripropylben Ruammonium, tri-n-butylbenzylammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, octadecyltri (2-hydroxyethyl) ammonium, Hydroxides such as tetrakis (hydroxyethyl) ammonium (X ⁿ⁻ = OH ⁻ ); hydrogenates such as hydrochloric acid, odorous acid and hydrofluoric acid; sulfuric acid (X ⁿ⁻ = HSO ₄ ⁻ , SO ₄ ²⁻ ), nitric acid , Phosphoric acid, carbonic acid (X ⁿ⁻ = HCO ₃ ⁻ , CO ₃ ²⁻ ), boric acid (X ⁿ⁻ = B (OH) ₄ ⁻ ), chloric acid, iodic acid, silicic acid, perchloric acid, chlorous acid, Oxoacid salts such as hypochlorous acid, chlorosulfuric acid, amidosulfuric acid, disulfuric acid and tripolyphosphoric acid; thioacid salts such as thiosulfuric acid; formic acid Acetic acid, propionic acid, butanoic acid, isobutyric acid, pentanoic acid, caproic acid, caprylic acid, capric acid, benzoic acid, carboxylic acid salts such as oxalate. Among these, hydroxide, sulfate, carbonate, borate, and carboxylate are preferable. Among the carboxylates, formate, acetate, and propionate are particularly preferable. Examples of such quaternary ammonium compounds include hydroxy choline formate (trimethyl-2-hydroxyethylammonium formate, triethyl-2-hydroxyethylammonium formate, etc.). One of these quaternary ammonium compounds may be used alone, or two or more thereof may be used in combination. Further, in addition to the quaternary ammonium compound, amines such as ammonia and triethylamine which are known decomposition accelerators for unstable terminals may be used in combination.

  The amount of the quaternary ammonium compound used in the above heat treatment method is converted to the amount of nitrogen derived from the quaternary ammonium compound represented by the following formula (b) relative to the total mass of the polyacetal copolymer and the quaternary ammonium compound. , 0.05 to 50 ppm by mass, and more preferably 1 to 30 ppm by mass.

Amount of quaternary ammonium compound = P × 14 / Q (b)
Here, in the formula (b), P represents the concentration (mass ppm) of the quaternary ammonium compound relative to the polyacetal copolymer, 14 represents the atomic weight of nitrogen, and Q represents the molecular weight of the quaternary ammonium compound.

  When the addition amount of the quaternary ammonium compound is less than 0.05 ppm by mass in terms of the amount of nitrogen derived from the quaternary ammonium compound, the decomposition and removal rate of the unstable terminal portion tends to decrease, and 50 mass If it exceeds ppm, the color tone of the polyacetal copolymer after the removal of the unstable end portion tends to deteriorate.

  The unstable end portion removal treatment of the polyacetal copolymer is achieved by heat-treating the polyacetal copolymer in a melted state at a temperature not lower than the melting point of the polyacetal copolymer and not higher than 260 ° C. The apparatus used for this heat treatment is not particularly limited, but it is preferable to perform heat treatment using an extruder, a kneader or the like. In addition, formaldehyde generated by decomposition is removed under reduced pressure. There are no particular restrictions on the method of adding the quaternary ammonium compound, and examples thereof include a method of adding it as an aqueous solution in the step of deactivating the polymerization catalyst and a method of spraying the polyacetal copolymer powder produced by the polymerization. Whichever addition method is used, it suffices if it is added in the step of heat-treating the polyacetal copolymer, and it may be poured into an extruder. Alternatively, when the filler or pigment is blended into the polyacetal resin composition using an extruder or the like, the compound may be attached to the resin pellet, and the unstable terminal portion may be removed in the subsequent blending step.

  The unstable terminal portion removal treatment may be performed after the polymerization catalyst in the polyacetal copolymer obtained by polymerization is deactivated or may be performed without deactivating the polymerization catalyst. The polymerization catalyst deactivation treatment is not particularly limited, but a representative example is a method of neutralizing and deactivating the polymerization catalyst in a basic aqueous solution such as amines. It is also effective to remove the unstable end after heating in an inert gas atmosphere at a temperature below the melting point of the polyacetal copolymer without deactivating the polymerization catalyst, and reducing the polymerization catalyst by volatilization. It is a simple method.

  By performing the unstable terminal portion removal treatment, a polyacetal resin in which the amount of formaldehyde generated when heated at 200 ° C. for 50 minutes in a nitrogen atmosphere is 100 ppm or less with respect to the amount of the polyacetal resin can be obtained.

[Hydrazine derivative (B)]
The hydrazine derivative (B) used in the present embodiment is not particularly limited as long as it has a hydrazine structure (NN) having a single bond between nitrogen atoms. For example, hydrazine; hydrazine hydrate; succinic monohydrazide Carboxylic acid monohydrazides such as glutaric acid monohydrazide, adipic acid monohydrazide, pimelic acid monohydrazide, speric acid monohydrazide, azelaic acid monohydrazide, sebacic acid monohydrazide; oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid Saturated aliphatic carboxylic acid dihydrazides such as dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, speric acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide; maleic acid dihydrazide Diolefins of monoolefinic unsaturated dicarboxylic acids such as dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide; aromatic carboxylic acid dihydrazides such as isophthalic acid dihydrazide, phthalic acid dihydrazide, 2,6-naphthalenedicarbodihydrazide; pyrohydric acid dihydrazide Trimer acid trihydrazide, cyclohexane tricarboxylic acid trihydrazide, benzene tricarboxylic acid trihydrazide, nitrilotriacetic acid trihydrazide, trihydrazide such as citric acid trihydrazide; pyromellitic acid tetrahydrazide, naphthoic acid tetrahydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1 , 4,5,8-naphthoic acid tetrahydrazide and the like; a low polymer having a carboxylic acid lower alkyl ester group is converted to hydrazine Is a polyhydrazide such as polyhydrazide obtained by reacting with hydrazine hydrate (hydrazine hydrate); carbonic dihydrazide; bissemicarbazide; diisocyanate such as hexamethylene diisocyanate and isophorone diisocyanate and polyisocyanate compounds derived therefrom, N, N-dimethyl Polyfunctional semicarbazide obtained by excessively reacting N, N-substituted hydrazine such as hydrazine and / or hydrazide exemplified above; hydrophilic group such as polyisocyanate compound and polyether polyol or polyethylene glycol monoalkyl ether An aqueous polyfunctional semicarbazide obtained by excessively reacting any of the above dihydrazides with an isocyanate group in a reaction product with an active hydrogen compound containing; And a mixture of the above water-based polyfunctional semicarbazide; bisacetyldihydrazone and the like.

  The hydrazine derivative (B) used in the present embodiment is preferably a hydrazine derivative different from the compound (C) described later. Among these, carboxylic acid hydrazide is preferable, and saturated aliphatic carboxylic acid hydrazide is more preferable. Specific examples of saturated aliphatic carboxylic acid hydrazides include carboxylic acids such as succinic acid monohydrazide, glutaric acid monohydrazide, adipic acid monohydrazide, pimelic acid monohydrazide, superic acid monohydrazide, azelaic acid monohydrazide, and sebacic acid monohydrazide. Carboxylic acid dihydrazides such as monohydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, superic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide.

  The hydrazine derivative (B) used in the present embodiment is more preferably a carboxylic acid dihydrazide represented by the following general formula (i).

In the formula (i), R ₁ represents a divalent substituted or unsubstituted hydrocarbon group, preferably an alkylene group having 2 to 20 carbon atoms.

  The hydrazine derivative (B) is particularly preferably at least one carboxylic acid dihydrazide selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide and dodecanedioic acid dihydrazide.

  The hydrazine derivative (B) described above may be used alone or in combination of two or more.

  As a result of studying various hydrazine derivatives (B), the present inventors have found that a compound having a plurality of hydrazide groups in the molecule is effective for the hydrazine derivative (B) to react efficiently with formaldehyde. As the hydrazide group in the molecule increases, the melting point of the hydrazide derivative (B) itself tends to increase and is considered to be higher than the melting point of the polyacetal resin (A). And when the difference of melting | fusing point of polyacetal resin (A) and melting | fusing point of hydrazine derivative (B) spreads, it will estimate that it becomes easy to produce | generate a mold deposit. Therefore, the present inventors believe that the formation of mold deposits can be suppressed by including the compound (C) that lowers the melting point of the hydrazine derivative (B). Hereinafter, the compound (C) that lowers the melting point of the hydrazine derivative (B) will be described in detail.

[Compound (C)]
Although the compound (C) used for this embodiment will not be specifically limited if it is a compound which reduces melting | fusing point of a hydrazine derivative (B), It is preferable that it is a hydrazine derivative different from the hydrazine derivative (B) mentioned above.

  For example, when the hydrazine derivative (B) is a monohydrazide, the compound (C) is preferably a monohydrazide and / or dihydrazide different from the hydrazine derivative (B), and the hydrazine derivative (B) is a dihydrazide. In this case, the compound (C) is more preferably dihydrazide and / or monohydrazide different from the hydrazine derivative (B). Thus, when the compound (C) is also a hydrazine derivative, and the combination of the hydrazide derivative (B) and the compound (C) is a combination of hydrazide derivatives having different structures, the hydrazide derivative ( It is effective for lowering the melting point of B).

  More specifically, when the hydrazine derivative (B) is a carboxylic acid hydrazide, the compound (C) is preferably a carboxylic acid hydrazide different from the hydrazine derivative (B).

  A more preferable combination of the hydrazide derivative (B) and the compound (C) is a combination of dihydrazide compounds, and more preferable is a combination of saturated aliphatic carboxylic acid dihydrazide compounds, that is, the hydrazine derivative (B ) Is a saturated aliphatic carboxylic acid dihydrazide, the compound (C) is more preferably a saturated aliphatic carboxylic acid dihydrazide different from the hydrazine derivative (B). When the hydrazine derivative (B) is a saturated aliphatic carboxylic acid dihydrazide, the compound (C) is a saturated aliphatic carboxylic acid dihydrazide and / or a saturated aliphatic carboxylic acid different from the hydrazine derivative (B). May be. Such a compound (C) is effective in lowering the melting point of the hydrazine derivative (B).

  When the hydrazine derivative (B) is a carboxylic acid dihydrazide represented by the general formula (i), the compound (C) may be a carboxylic acid hydrazide different from the hydrazine derivative (B). preferable. Further, when the hydrazine derivative (B) is at least one carboxylic acid dihydrazide (b) selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide and dodecanedioic acid dihydrazide, the compound (C) is adipine One or more carboxylic acid dihydrazides (c) selected from the group consisting of acid dihydrazide, sebacic acid dihydrazide and dodecanedioic acid dihydrazide (provided that the carboxylic acid dihydrazide (b) and the carboxylic acid dihydrazide (c) Preferably).

  For example, when the hydrazine derivative (B) is adipic acid dihydrazide, the compound (C) is sebacic acid dihydrazide and / or dodecanedioic acid dihydrazide, and when the hydrazine derivative (B) is sebacic acid dihydrazide, the compound (C) is preferably adipic acid dihydrazide and / or dodecanedioic acid dihydrazide.

  Such a combination of the hydrazine derivative (B) and the compound (C) includes a combination of adipic acid dihydrazide as the hydrazine derivative (B), a combination of sebacic acid dihydrazide as the compound (C), and the hydrazine derivative (B). A combination of sebacic acid dihydrazide as the compound and dodecanedioic acid dihydrazide as the compound (C) is preferable.

  The compound (C) mentioned above may be used individually by 1 type, and may be used together 2 or more types.

  By forming a mold using the polyacetal resin composition containing such a compound (C) together with the hydrazine derivative (B), generation of mold deposits in the mold can be suppressed. And it exists in the tendency which can obtain the vehicle interior and mechanism components with a favorable surface external appearance. Furthermore, recycling molding tends to be easy.

  Specific examples of the present inventors' various studies of the hydrazine derivative (B) and the compound (C) are shown below.

  The present inventors used a differential scanning calorimeter (trade name “DSC7”, manufactured by Perkin Elmer Co., Ltd.) with respect to a mixture of various two kinds of carboxylic acid hydrazides in a mass ratio of 1: 1. ) To (III) in order, and among the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until the mixture melts, the peak of the endothermic peak having the largest endothermic capacity is obtained. It was found that the temperature shown (hereinafter also referred to as “maximum endothermic peak temperature”) behaves differently from the maximum endothermic peak temperature of each carboxylic acid hydrazide before mixing.

  For example, when terephthalic acid dihydrazide is heated at a rate of 2.5 ° C./min using a differential scanning calorimeter (trade name “DSC7”, manufactured by Perkin Elmer Co., Ltd.), an endothermic peak apex is observed at 324 ° C. Similarly, when the temperature of isophthalic acid dihydrazide is raised, the end of the endothermic peak is observed at 226 ° C. The peak of the endothermic peak is observed at 181 ° C. for adipic acid dihydrazide, 188 ° C. for sebacic acid dihydrazide, and 188 ° C. for dodecanedioic acid dihydrazide.

  Further, a differential scanning calorimeter (trade name, manufactured by Perkin Elmer Co., Ltd.) was used for one carboxylic acid hydrazide or a mixture obtained by mixing and pulverizing two carboxylic acid hydrazides in a mortar at a mass ratio of 1: 1. The endothermic peak obtained when the temperature is increased at a rate of 2.5 ° C./min until the mixture is melted after sequentially performing the above operations (I) to (III) using “DSC7”). By confirming, the temperature which shows the peak of the endothermic peak with the largest endothermic capacity is measured.

  For example, when adipic acid dihydrazide was measured alone, two endothermic peaks were observed, and the peaks were 176 ° C. and 171 ° C. The endothermic capacity (hereinafter also referred to as “ΔH”) calculated from the area of each endothermic peak is 5.4 J / g and 229.2 J / g in this order. The ratio of ΔH of the endothermic peak at 171 ° C. to the total amount of ΔH, that is, the ratio of the peak area of the endothermic peak at 171 ° C. to the total peak area of these endothermic peaks is 98% (see FIG. 1). . Further, when sebacic acid dihydrazide alone was measured in the same manner, endothermic peaks were observed at 185 ° C., 180 ° C. and 172 ° C., and each ΔH was 5.4 J / g, 32.4 J / g and 16.4 J / g. Furthermore, the ratio of ΔH of each endothermic peak to the total amount of ΔH is 10% at 185 ° C., 60% at 180 ° C., and 30% at 172 ° C. (see FIG. 2). Similarly, when dodecanedioic acid dihydrazide alone was measured, endothermic peaks were observed at 183 ° C., 177 ° C. and 171 ° C., and each ΔH was 2.4 J / g, 18.1 J / g and 32.4 J / g, respectively. g. Furthermore, the ratio of ΔH of each endothermic peak to the total amount of ΔH is 5% at 183 ° C., 34% at 177 ° C., and 61% at 171 ° C. The temperature indicated by the apex of the endothermic peak having the largest ΔH is referred to as “maximum endothermic peak temperature”. The maximum endothermic peak temperature of adipic acid dihydrazide is 171 ° C., the maximum endothermic peak temperature of sebacic acid dihydrazide is 180 ° C. The maximum endothermic peak temperature of diacid dihydrazide is 171 ° C.

  The maximum endothermic peak temperature in the DSC curve of a 1: 1 mass ratio mixture of adipic dihydrazide and sebacic acid dihydrazide shows 154 ° C., and ΔH at 154 ° C. is 91% with respect to the total amount of ΔH (FIG. 3). The maximum endothermic peak temperature of a 1: 1 mass mixture of adipic acid dihydrazide and dodecanedioic acid dihydrazide shows 151 ° C., and ΔH at 151 ° C. is 98% with respect to the total amount of ΔH. The maximum endothermic peak temperature of a 1: 1 mass mixture of sebacic acid dihydrazide and dodecanedioic acid dihydrazide shows 144 ° C., and ΔH at 144 ° C. is 80% with respect to the total amount of ΔH. That is, in these mixtures, the above-mentioned operations (I) to (III) are performed on the mixture having the mass ratio of 1: 1 using a differential scanning calorimeter (trade name “DSC7”, manufactured by Perkin Elmer Co., Ltd.). After performing in sequence, it can be seen that the peak of the endothermic peak exists when the temperature is raised at a rate of 2.5 ° C./min until the mixture melts.

  On the other hand, when a 1: 1 mass ratio mixture of sebacic acid dihydrazide and isophthalic acid dihydrazide is simply heated to 250 ° C. at 2.5 ° C./min, an endothermic peak is observed at 181 ° C. However, after maintaining at 250 ° C. for 2 minutes, the temperature was decreased to 100 ° C. at a temperature decrease rate of 10 ° C./min, and then the temperature was increased to 250 ° C. at a temperature increase rate of 2.5 ° C./min. It can be seen that no crystallization occurs after the first melting (see FIG. 4). Similarly, a 1: 1 mass ratio mixture of adipic acid dihydrazide and isophthalic acid dihydrazide, a 1: 1 mass ratio mixture of adipic acid dihydrazide and terephthalic acid dihydrazide, and a mass ratio of terephthalic acid dihydrazide and isophthalic acid dihydrazide. The 1: 1 mixture was heated to 350 ° C. at a heating rate of 2.5 ° C./min, held at 350 ° C. for 2 minutes, then cooled to 100 ° C. at a cooling rate of 10 ° C./min, and then heated Although the temperature was raised to 350 ° C. at a rate of 2.5 ° C./min, no endothermic peak was observed. This is because the mixture is heated and melted at a heating rate of 2.5 ° C./min, held for 2 minutes, and then cooled to 100 ° C. at a cooling rate of 10 ° C./min. It shows that the endothermic peak disappears when the temperature is raised at 5 ° C./min.

  As a result of further investigations, the inventors of the present invention contain a polyacetal resin (A), a hydrazine derivative (B), and a compound (C) that lowers the melting point of the hydrazine derivative (B) as described above. Use of a polyacetal resin composition obtained from a raw material composition, satisfying the above conditional expressions (1) and (2), and having a melt flow rate of 2 to 10 g / 10 minutes, suppresses the formation of mold deposits in the mold. it can. And, it is thought that the surface appearance of the resulting automobile interior / mechanical parts can be greatly improved, and that recycle molding becomes easier.

  The total content of the hydrazine derivative (B) and the compound (C) is preferably 0.03 to 0.2 parts by mass with respect to 100 parts by mass of the polyacetal resin (A). More preferably, it is -0.2 mass part, More preferably, it is 0.05-0.2 mass part. When the total content of the hydrazine derivative (B) and the compound (C) is less than 0.03 parts by mass with respect to 100 parts by mass of the polyacetal resin (A), the amount of formaldehyde released during recycle molding increases. If the amount is more than 0.2 parts by mass, mold deposits tend to be easily generated in the mold in the production of automobile interior and mechanism parts.

  Moreover, it is preferable that mass ratio ((B) :( C)) of the said hydrazine derivative (B) and the said compound (C) is 2: 8-8: 2, and is 3: 7-7: 3. More preferably. When the mass ratio is within the above range, the maximum endothermic peak temperature of the mixture of the hydrazine derivative (B) and the compound (C) tends to be lower than the maximum endothermic peak temperature of the polyacetal resin (A). It is in.

[Additive]
A suitable additive can be mix | blended with the polyacetal resin composition used for this embodiment according to a use. Specific examples of such additives include antioxidants, polymers or compounds having formaldehyde-reactive nitrogen, formic acid scavengers, mold release agents and the like.

  In addition, the compounding quantity of each additive in a polyacetal resin composition becomes like this. Preferably it is 0.001-0.8 mass part with respect to 100 mass parts of polyacetal resin (A), More preferably, it is 0.01-0.7 mass. Part.

[Antioxidant]
As the antioxidant, a hindered phenol antioxidant is preferable. Specific examples of the antioxidant include n-octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) -propionate and n-octadecyl-3- (3′-methyl). -5'-t-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexane Diol-bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis- [3- (3,5-di-t-butyl- 4-hydroxyphenyl) -propionate], triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate], pentaerythritol te Rakisu [methylene-3- (3 ', 5'-di -t- butyl-4'-hydroxyphenyl) propionate], and methane. Among these, preferred antioxidants are triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] and pentaerythritol tetrakis [methylene-3- (3 ′ , 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane. These antioxidants may be used individually by 1 type, and may be used in combination of 2 or more type.

[Polymer or compound having formaldehyde-reactive nitrogen]
The polymer or compound having formaldehyde-reactive nitrogen is a polymer or compound (monomer) having a nitrogen atom capable of reacting with formaldehyde in its molecule. Specific examples thereof include nylon 4-6, nylon 6, Polyamide resins such as nylon 6-6, nylon 6-10, nylon 6-12, nylon 12, and polymers thereof, for example, nylon 6 / 6-6 / 6-10, nylon 6 / 6-12 . Examples of the polymer or compound having formaldehyde-reactive nitrogen include acrylamide and derivatives thereof, and copolymers of acrylamide and derivatives thereof with other vinyl monomers. More specifically, a poly-β-alanine copolymer obtained by polymerizing acrylamide and its derivatives and other vinyl monomers in the presence of a metal alcoholate can be mentioned. Further, as polymers or compounds having formaldehyde-reactive nitrogen, amide compounds, amino-substituted triazine compounds, adducts of amino-substituted triazine compounds and formaldehyde, condensates of amino-substituted triazine compounds and formaldehyde, urea, urea derivatives, imidazole Also included are compounds and imide compounds.

  Specific examples of the amide compound include polycarboxylic acid amides such as isophthalic acid diamide and anthranilamides. Specific examples of the amino-substituted triazine compound include 2,4-diamino-sym-triazine, 2,4,6-triamino-sym-triazine, N-butylmelamine, N-phenylmelamine, N, N-diphenylmelamine, N , N-diallylmelamine, benzoguanamine (2,4-diamino-6-phenyl-sym-triazine), acetoguanamine (2,4-diamino-6-methyl-sym-triazine), 2,4-diamino-6-butyl -Sym-triazine is mentioned. Specific examples of the adduct of an amino-substituted triazine compound and formaldehyde include N-methylol melamine, N, N′-dimethylol melamine, and N, N ′, N ″ -trimethylol melamine. Specific examples of condensates with formaldehyde include melamine / formaldehyde condensates, and examples of urea derivatives include N-substituted urea, urea condensate, ethylene urea, hydantoin compound, and ureido compound. Specific examples of the substituted urea include methylurea, alkylenebisurea, and aryl-substituted urea substituted with a substituent such as an alkyl group, etc. Specific examples of the urea condensate include a condensate of urea and formaldehyde. Specific examples of hydantoin compounds include hydantoin, 5, -.. Dimethylhydantoin, specific examples of the 5,5-diphenylhydantoin and the like ureido compounds, specific examples of allantoin and the like imide compounds succinimide, glutarimide, and phthalimide.

  These polymers or compounds having a formaldehyde-reactive nitrogen atom may be used alone or in combination of two or more.

[Formic acid scavenger]
The formic acid scavenger can efficiently neutralize formic acid, and examples thereof include the above-mentioned amino-substituted triazine compounds, condensates of amino-substituted triazine compounds and formaldehyde, such as melamine / formaldehyde condensates.

  Examples of the formic acid scavenger include alkali metal or alkaline earth metal hydroxides, inorganic acid salts, carboxylate salts, and alkoxides. Examples thereof include metal hydroxides such as sodium, potassium, magnesium, calcium, and barium, and carbonates, phosphates, silicates, borates, and carboxylates of the above metals. The carboxylic acid of the carboxylate is preferably a saturated or unsaturated aliphatic carboxylic acid having 10 to 36 carbon atoms, and these carboxylic acids may have a hydrogen atom substituted with a hydroxyl group. Specific examples of saturated or unsaturated aliphatic carboxylates include calcium dimyristate, calcium dipalmitate, calcium distearate, (myristic acid-palmitic acid) calcium, (myristic acid-stearic acid) calcium, ( Palmitic acid-stearic acid) calcium. Among these, calcium dipalmitate, calcium distearate, and magnesium silicate are preferable.

[Release agent]
As the release agent, alcohols, fatty acids and fatty acid esters thereof are preferably used, and particularly preferable release agents include ethylene glycol distearate.

[Other additives]
In the polyacetal resin composition used in the present embodiment, a suitable known additive can be further blended as necessary within a range not impairing the object of the present invention. Specific examples include inorganic fillers, crystal nucleating agents, conductive materials, thermoplastic resins, thermoplastic elastomers, and pigments.

[Inorganic filler]
Examples of inorganic fillers include fibrous, powder particle, plate and hollow inorganic fillers. Examples of the fibrous inorganic filler include glass fiber, carbon fiber, silicone fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, copper And inorganic fibers such as metal fibers such as brass. In addition, whiskers such as potassium titanate whisker and zinc oxide whisker having a short fiber length are also exemplified as fibrous inorganic fillers.

  Examples of powdered inorganic fillers include silicates such as carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, magnesium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, wollastonite, and oxidation. Metal oxides such as iron, titanium oxide, and alumina, metal sulfates such as calcium sulfate and barium sulfate, carbonates such as magnesium carbonate and dolomite, other silicon carbide, silicon nitride, boron nitride, and various metal powders .

  Examples of the plate-like inorganic filler include mica, glass flakes, and various metal foils. Examples of the hollow inorganic filler include glass balloons, silica balloons, shirasu balloons, and metal balloons. These inorganic fillers are used alone or in combination of two or more. These inorganic fillers may or may not be subjected to a surface treatment, but those subjected to a surface treatment may be preferable from the viewpoint of the smoothness of the molding surface and mechanical properties. A conventionally well-known thing can be used as a surface treating agent used for the surface treatment of an inorganic filler. Examples of the surface treating agent include various coupling treating agents such as silane, titanate, aluminum, and zirconium. More specifically, as a surface treatment agent, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, isopropyltristearoyl titanate, diisopropoxyammonium ethyl acetate, n-Butyl zirconate is mentioned.

  A high melting point organic fibrous material such as an aromatic polyamide resin, a fluororesin, or an acrylic resin may be added together with or in place of the inorganic filler.

[Conductive agent]
Examples of the conductive agent include conductive carbon black, metal powder, or fiber.

[Thermoplastic resin and thermoplastic elastomer]
Examples of the thermoplastic resin include polyolefin resin, acrylic resin, styrene resin, polycarbonate resin, and uncured epoxy resin. In addition, modified products of these resins are also included in the thermoplastic resin. Examples of the thermoplastic elastomer include polyurethane elastomers, polyester elastomers, polystyrene elastomers, and polyamide elastomers.

[Pigment]
Examples of the pigment include inorganic pigments, organic pigments, metallic pigments, and fluorescent pigments. Inorganic pigments are those commonly used for coloring resins, such as zinc sulfide, titanium oxide, barium sulfate, titanium yellow, cobalt blue, combustion pigments, carbonates, phosphates, acetic acid. Examples include salt, carbon black, acetylene black, and lamp black. Examples of organic pigments include condensed azo, quinone, phthalocyanine, monoazo, diazo, polyazo, anthraquinone, heterocyclic, perinone, quinacridone, thioindico, perylene, and dioxazine. Pigments.

<Method for producing polyacetal resin composition>
The method for producing the polyacetal resin composition used in the present embodiment is not particularly limited. For example, the polyacetal resin (A), the hydrazine derivative (B), and the compound (C) are mixed in advance with a Henschel mixer, a tumbler, a V-shaped blender, or the like to obtain a raw material composition containing them, It can be produced by a method generally known as a production method of a polyacetal resin composition, such as a production method in which a raw material composition is melt-kneaded using a single-screw or multi-screw kneading extruder. Among them, a method using a twin-screw kneading extruder equipped with a decompression device is preferable as an extruder for melt kneading the raw material composition.

  In addition, without mixing the polyacetal resin (A), the hydrazine derivative (B), and the compound (C) in advance, each component can be singly or in a batch fed continuously to the extruder using a quantitative feeder or the like. It is also possible to obtain a raw material composition in an extruder and produce a polyacetal resin composition from the raw material composition. In addition, a high-concentration master batch composed of the polyacetal resin (A), the hydrazine derivative (B) and the compound (C) is prepared in advance, and is further added to the polyacetal resin (A) at the time of extrusion melt kneading or injection molding. A polyacetal resin composition can also be obtained by diluting.

  The total addition amount of the hydrazine derivative (B) and the compound (C) is preferably 0.03 to 0.2 parts by mass with respect to 100 parts by mass of the polyacetal resin (A). More preferably, it is -0.2 mass part, More preferably, it is 0.05-0.2 mass part. When the total addition amount of the hydrazine derivative (B) and the compound (C) is less than 0.03 parts by mass, the amount of formaldehyde released during recycle molding tends to increase, which is more than 0.2 parts by mass. In the production of automobile interiors and mechanical parts, it tends to be easy to generate mold deposits in the mold.

  Moreover, it is preferable that mass ratio ((B) :( C)) of the said hydrazine derivative (B) and the said compound (C) is 2: 8-8: 2, It is 3: 7-7: 3. More preferably. When the mass ratio is within the above range, the maximum endothermic peak temperature of the mixture of the hydrazine derivative (B) and the compound (C) tends to be lower than the maximum endothermic peak temperature of the polyacetal resin (A). It is in.

  In addition, in the obtained polyacetal resin composition, the reaction product from carboxylic acid dihydrazide may be contained. Examples of such a reaction product include a reaction product of carboxylic acid dihydrazide and formaldehyde.

  Next, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples unless it exceeds the gist.

  Measurement and evaluation of various physical properties in the following Examples and Comparative Examples were performed as follows.

(1) Melt flow rate In accordance with ASTM-D1238, the melt flow rate was measured under the conditions of 190 ° C and 2169 g.

(2) Maximum endothermic peak temperature (° C) in DSC curve
The following operations (I) to (III) were sequentially performed on the measurement target component using a differential scanning calorimeter (trade name “DSC7”, manufactured by PerkinElmer Co., Ltd.). After the operation, among the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until the measurement target component melts, the temperature (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity, The maximum endothermic peak temperature (° C.) in the DSC curve of the measurement target component was used.
(I) The temperature was increased at a rate of 320 ° C./min from a temperature lower than the first endothermic peak of the measurement target component to a temperature at which the measurement target component melts.
(II) It was held for 2 minutes at a temperature (200 ° C.) at which the component to be measured was melted.
(III) The temperature was lowered to 100 ° C. at a rate of 10 ° C./min.

(3) Evaluation of mold deposit resistance (MD) resistance Using an injection molding machine (trade name “IS-100GN” manufactured by Toshiba Machine Co., Ltd.), the cylinder temperature was set to 200 ° C., and the mold temperature was set to 80 ° C. A test piece was obtained by molding the obtained polyacetal resin composition under the conditions such that the injection pressure was 80 MPa, the injection time was 30 seconds, and the cooling time was 30 seconds, and the resin composition was not completely filled in the test piece mold. It was. The mass of the test piece was 96% by mass of the test piece obtained by completely filling the mold with the resin composition. However, when the melt flow rate of the raw material polyacetal resin is different as in polyacetal resins (a-2), (a-3), (a-6) and (a-7) described later, the weight of the molded product is The injection pressure was adjusted to be equivalent.

  The shape of the test piece is a large flat plate (130 mm in length, 110 mm in width, 3 mm in thickness) on the assumption that the size of a molded product becomes large or a large number of pieces are produced in the manufacture of automobile interiors and mechanical parts. did.

  The mold deposit (MD) in the mold after 300 shots of the test piece were molded was visually observed and evaluated according to the following criteria.

(Standard)
“A”: MD was not recognized.

      “B”: MD was slightly recognized.

      "C": Obvious MD was recognized.

(4) Evaluation of high temperature durability (a) Evaluation of bending fatigue characteristics Using an injection molding machine (trade name “IS-100GN” manufactured by Toshiba Machine Co., Ltd.), the cylinder temperature is 200 ° C. and the mold temperature is 80 ° C. An ASTM D671 TYPEI test piece was prepared using a polyacetal resin composition described later, with an injection pressure of 70 MPa, an injection time of 20 seconds, and a cooling time of 20 seconds. However, when the melt flow rate of the raw material polyacetal resin is different as in polyacetal resins (a-2), (a-3), (a-6) and (a-7), the weight of the molded product is equivalent. The injection pressure was adjusted so that The shape and dimensions of the test piece are shown in FIG.

Using repeated vibration fatigue tester (manufactured by Toyo Seiki Co., Ltd.), the bending fatigue property evaluation test of the above test pieces, test temperature 60 ° C., number of repetitions speed 1800 rev / min, bending stress 15 MPa, 1 × 10 ⁷ Conducted up to once.

  When the above-mentioned test piece broke, or when the maximum deflection of the test piece exceeded ± 8 mm before breaking, the number of tests at that time was recorded.

In general, bending fatigue characteristics required for automobile interior / mechanical parts made of polyacetal resin are as follows: environmental temperature: around 60 ° C at maximum, maximum number of repetitions: 1800 times / minute, maximum bending fatigue stress: about 15 MPa. The maximum number of fatigue times is estimated to be about 1 × 10 ⁷ times.

(B) Evaluation of tensile creep characteristics Using an injection molding machine (trade name “IS-100GN” manufactured by Toshiba Machine Co., Ltd.), the cylinder temperature is 200 ° C., the mold temperature is 80 ° C., the injection pressure is 80 MPa, and the injection time is 40. Second, the cooling time was set to 20 seconds, and a modified shape was prepared based on a JIS No. 2 dumbbell specimen by molding using a polyacetal resin composition described later. However, when the melt flow rate of the raw material polyacetal resin is different as in polyacetal resins (a-2), (a-3), (a-6), and (a-7), the weight of the molded product is equivalent. The injection pressure was adjusted so that The shape and dimensions of the test piece are shown in FIG.

  Using the creep tester (manufactured by Toyo Seiki Co., Ltd.), the above-described tensile creep property evaluation test of the test piece was performed. The test temperature was 80 ° C., and the test was conducted up to 1000 hours at a tensile stress of 15 MPa. When the test piece broke along the way, the time at that time was recorded.

  In general, the tensile creep characteristics required for automobile interior / mechanical parts made of polyacetal resin are estimated to be about 1000 hours at the maximum under the conditions of operating environment temperature: around 80 ° C. and maximum tensile stress: about 15 MPa. .

(5) Evaluation of the amount of formaldehyde gas generated before and after the high temperature durability test The amount of formaldehyde generated from the test pieces before and after the test of the bending fatigue property and tensile creep property was measured by the following VDA275. The measured amount was estimated as formaldehyde generated from the molded product. The test piece for tensile creep properties was used without cutting. A part of the test piece for bending fatigue characteristics was cut and used. The cutting dimensions and the like are shown in FIG.

(VDA275)
First, 50 mL of distilled water and a test piece prepared during the evaluation of the high temperature durability were accommodated in a polyethylene container and sealed. Subsequently, after heating the polyethylene container at 60 ° C. for 3 hours, formaldehyde generated in distilled water was reacted with acetylacetone in the presence of ammonium ions. The absorption peak at a wavelength of 412 nm was measured for the obtained reaction product using a UV spectrometer, and the amount of formaldehyde generated (kg / kg) per kg of the test piece was determined. However, in the fatigue test, the amount of formaldehyde generated is 1 × 10 ⁷ times for the bending fatigue property and 1000 hours for the tensile creep test, and the property evaluation test is not completed due to breakage of the test piece. Was not measured.

[Raw material component of polyacetal resin composition]
In the examples and comparative examples, the following were used as raw material components of the polyacetal resin composition.

<Polyacetal resin (a-1)>
A biaxial self-cleaning type polymerization machine (L / D = 8) with a jacket capable of passing a heat medium was adjusted to 80 ° C. Then, 4 kg / hr of trioxane, 42.8 g / hr of 1,3-dioxolane as a comonomer (0.039 mol with respect to 1 mol of trioxane), methylal as a chain transfer agent (water content 1.3%, methanol amount 0. 99%) was continuously added to the polymerizer at a ratio of 1.50 × 10 ⁻³ mol with respect to 1 mol of trioxane. Furthermore, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerizer at a ratio of 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane to carry out polymerization.

  The polyacetal copolymer discharged from the polymerization machine was put into a 0.1% aqueous solution of triethylamine to deactivate the polymerization catalyst. The polyacetal copolymer in which the polymerization catalyst was deactivated was separated and recovered by filtration with a centrifuge. Thereafter, 100 parts by mass of the separated and collected polyacetal copolymer is added with 1 part by mass of a choline formate (triethyl-2-hydroxyethylammonium formate-containing aqueous solution) as a quaternary ammonium compound, and mixed uniformly. It was further dried at 120 ° C. The amount of choline formate added was adjusted by adjusting the concentration of choline formate in the aqueous solution containing choline formate to be added. An amount of choline formate in an amount of 20 mass ppm in terms of the amount of nitrogen derived from hydroxy choline formate represented by the formula (b) was added.

  The dried polyacetal copolymer is supplied to a vented twin screw extruder, 0.5 parts by mass of water is added to 100 parts by mass of the polyacetal copolymer melted in the extruder, and the extruder set temperature is 200 ° C. Then, the unstable end portion was decomposed and removed in a residence time of 7 minutes in the extruder.

  The polyacetal copolymer in which the unstable terminal portion was decomposed was devolatilized under a condition of a vent vacuum of 20 Torr, extruded as a strand from the extruder die portion, and pelletized. In this way, the pelletized polyacetal resin (a-1) was obtained.

  When the melt flow rate of the obtained polyacetal resin (a-1) was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g.

  Moreover, it was 165 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the obtained polyacetal resin (a-1) was calculated | required as mentioned above.

<Polyacetal resin (a-2)>
A polyacetal resin (a-2) was obtained in the same manner as the polyacetal resin (a-1) except that the amount of methylal of the chain transfer agent was changed so that the melt flow rate was 5 g / 10 min. It was 165 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the obtained polyacetal resin (a-2) was calculated | required as mentioned above.

<Polyacetal resin (a-3)>
A polyacetal resin (a-3) was obtained in the same manner as the polyacetal resin (a-1) except that the amount of methylal of the chain transfer agent was changed so that the melt flow rate was 10 g / 10 min. It was 165 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the obtained polyacetal resin (a-3) was calculated | required as mentioned above.

<Polyacetal resin (a-4)>
A polyacetal resin (a-4) was obtained in the same manner as the polyacetal resin (a-1) except that methylal (water content: 45 ppm, methanol content: 0.58%) was used instead of methylal as the chain transfer agent. .

  When the melt flow rate of the obtained polyacetal resin (a-4) was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g.

  Moreover, it was 165 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the obtained polyacetal resin (a-4) was calculated | required as mentioned above.

<Polyacetal resin (a-5)>
A biaxial self-cleaning type polymerization machine (L / D = 8) with a jacket capable of passing a heating medium was adjusted to 80 ° C. Subsequently, trioxane was continuously added to the polymerizer at a rate of 4 kg / hr and 1,3-dioxolane as a comonomer at a rate of 42.8 g / h (0.039 mol with respect to 1 mol of trioxane). Furthermore, boron trifluoride di-n-butyl etherate as a polymerization catalyst was continuously added to the polymerizer at a ratio of 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane to carry out polymerization. To 1000 parts by mass of the obtained crude polyacetal, 0.8 part by mass of triphenylphosphine was added and mixed uniformly to obtain a polyacetal resin (a-5).

  When the melt flow rate of the obtained polyacetal resin (a-5) was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g.

  Moreover, when the maximum endothermic peak temperature (degreeC) in the DSC curve of the obtained polyacetal resin (a-5) was calculated | required as mentioned above, it was 165 degreeC.

<Polyacetal resin (a-6)>
A polyacetal resin (a-6) was obtained in the same manner as the polyacetal resin (a-1) except that the amount of methylal of the chain transfer agent was changed so that the melt flow rate was 1.5 g / 10 min. It was 165 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the obtained polyacetal resin (a-6) was calculated | required as mentioned above.

<Polyacetal resin (a-7)>
A polyacetal resin (a-7) was obtained in the same manner as the polyacetal resin (a-1) except that the amount of methylal of the chain transfer agent was changed so that the melt flow rate was 15 g / 10 min. It was 165 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the obtained polyacetal resin (a-7) was calculated | required as mentioned above.

<Hydrazine derivative (B) and compound (C)>
Adipic acid dihydrazide as carboxylic acid hydrazide (bc-1), sebacic acid dihydrazide as carboxylic acid hydrazide (bc-2), dodecanedioic acid dihydrazide as carboxylic acid hydrazide (bc-3), and carboxylic acid hydrazide (bc-4) ) And isophthalic acid dihydrazide as carboxylic acid hydrazide (bc-5). It selected suitably from these and used as said hydrazine derivative (B) and said compound (C).

  The maximum endothermic peak temperature (° C.) in the DSC curve of the carboxylic acid hydrazide (bc-1) to (bc-5) was determined as described above. The results are shown in Table 1.

[Two-screw extruder with vent]
In Examples and Comparative Examples, TEM26SS manufactured by Toshiba Machine Co., Ltd. was used as a twin screw extruder with a vent.

[Examples 1 to 14]
Polyacetal resin (A) and hydrazine derivative (B) compound (C) were added in the types and proportions shown in Table 2 and mixed with a tumbler to obtain a raw material composition. The obtained raw material composition was melt-kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition.

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Further, the maximum endothermic peak temperature (° C.) in the DSC curve of the mixture of the hydrazine derivative (B) and the compound (C) used in each example was determined as described above. The results are shown in Table 2.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Example 1 and Examples 4 to 14 was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g. Met. The melt flow rates of the polyacetal resin compositions obtained in Example 2 and Example 3 measured in the same manner were 5 g / 10 minutes and 10 g / 10 minutes in this order.

[Comparative Example 1]
Pellets of the polyacetal resin composition were produced by melt-kneading 100 parts by mass of the polyacetal resin (a-1) with a twin screw extruder with a vent.

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Example 1 was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g.

[Comparative Example 2]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-2) was used instead of the polyacetal resin (a-1).

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Example 2 was measured according to ASTM-D1238 as described above, it was 5 g / 10 min under the conditions of 190 ° C. and 2169 g.

[Comparative Example 3]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-3) was used instead of the polyacetal resin (a-1).

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Example 3 was measured according to ASTM-D1238 as described above, it was 10 g / 10 min under the conditions of 190 ° C. and 2169 g.

[Comparative Example 4]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-4) was used instead of the polyacetal resin (a-1).

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Example 4 was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g.

[Comparative Example 5]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-5) was used instead of the polyacetal resin (a-1).

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Example 5 was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g.

[Comparative Examples 6 to 13]
Carboxylic acid hydrazide was added in the types and proportions shown in Table 3 to 100 parts by mass of the polyacetal resin (a-1), and mixed with a tumbler to obtain a raw material composition. The obtained raw material composition was melt-kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition.

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Examples 6 to 13 was measured according to ASTM-D1238 as described above, it was 3 g / 10 min under the conditions of 190 ° C. and 2169 g.

  Moreover, the maximum endothermic peak temperature (degreeC) in the DSC curve of the carboxylic acid hydrazide used in Comparative Examples 6 to 13 was determined as described above. The results are shown in Table 3.

  The maximum endothermic peak temperature (° C.) of the carboxylic acid hydrazide used alone in Comparative Examples 6 and 13 was 171 ° C. in Comparative Example 6 and 180 ° C. in Comparative Example 13. In Comparative Examples 7 to 10, there was no maximum endothermic peak temperature (° C.) in the mixture of the two carboxylic acid hydrazides used. The maximum endothermic peak temperatures (° C.) of the mixture of the two carboxylic acid hydrazides used in Comparative Examples 11 and 12 were 172 ° C. and 168 ° C., respectively.

[Comparative Example 14]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-6) was used instead of the polyacetal resin (a-1).

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Example 14 was measured according to ASTM-D1238 as described above, it was 1.5 g / 10 min under the conditions of 190 ° C. and 2169 g.

  Moreover, it was 154 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the carboxylic acid hydrazide used in the comparative example 14 was calculated | required as mentioned above.

[Comparative Example 15]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-7) was used instead of the polyacetal resin (a-1).

  Using the obtained pellets, as described above, resistance to mold deposit (MD) on a large flat plate, evaluation of bending fatigue characteristics, measurement of formaldehyde generation before and after the test, and evaluation of tensile creep characteristics and before and after the test The amount of formaldehyde generated was measured at The results are shown in Table 4.

  Moreover, when the melt flow rate of the polyacetal resin composition obtained in Comparative Example 15 was measured according to ASTM-D1238 as described above, it was 15 g / 10 min under the conditions of 190 ° C. and 2169 g.

  Moreover, it was 154 degreeC when the maximum endothermic peak temperature (degreeC) in the DSC curve of the carboxylic acid hydrazide used in the comparative example 15 was calculated | required as mentioned above.

From the results shown in the table, according to the present invention, it is possible to suppress the formation of mold deposits in the mold even when the molding size is increased or a multi-cavity mold is used in the molding of the polyacetal resin composition. I understood. In addition, it was suggested that it is possible to provide an automobile interior / mechanism component with a stable and low amount of formaldehyde generated even when it is used under a high temperature for a long time or under repeated stress.

  The automobile interior / mechanism parts according to the present invention have a mechanical property balance of polyacetal resin, and in the production of automobile interior / mechanism parts, even when the molding size is large or a multi-cavity mold is used. The generation of mold deposits in the mold can be suppressed. Furthermore, the automobile interior / mechanism component according to the present invention stably generates a small amount of formaldehyde even when it is used for a long time under high temperature and when it is subjected to repeated stress.

A: Overall length: 108mm
B; Width at both ends: 15mm
C: Length of parallel part: 33mm
D: Width of parallel part: 6mm
E: Distance between marked lines: 25 mm
F: Distance between grips: 65mm
G: Thickness: 3mm

Claims (10)

Obtained from a raw material composition containing a polyacetal resin (A), a hydrazine derivative (B), and a compound (C) that lowers the melting point of the hydrazine derivative (B), the following conditional expressions (1) and (2) And the hydrazine derivative (B) contains at least one carboxylic acid dihydrazide (b) selected from the group consisting of adipic acid dihydrazide and sebacic acid dihydrazide, and the compound (C) comprises adipic acid dihydrazide and sebacic acid One or more carboxylic acid dihydrazides (c) selected from the group consisting of dihydrazides (however, the carboxylic acid dihydrazide (b) and the carboxylic acid dihydrazide (c) are different from each other), and the melt flow rate is 2 to 2. Automotive interior / mechanism part obtained by using a polyacetal resin composition of 10 g / 10 min .
T1 <T2 (1)
T1 <T3 (2)
(In the formulas (1) and (2),
T1 is obtained by sequentially performing the following operations (I) to (III) on the mixture of the hydrazine derivative (B) and the compound (C) using a differential scanning calorimeter, and then the mixture melts. Among the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until, the temperature (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity,
T2 is 2.5 until the hydrazine derivative (B) melts after sequentially performing the following operations (I) to (III) on the hydrazine derivative (B) using a differential scanning calorimeter. Among the endothermic peaks obtained when the temperature is raised at a rate of ° C./min, the endothermic peak having the highest endothermic capacity is the temperature (° C.).
T3 is 2.5 until the polyacetal resin (A) is melted after the following operations (I) to (III) are sequentially performed on the polyacetal resin (A) using a differential scanning calorimeter. Of the endothermic peaks obtained when the temperature is raised at a rate of ° C./minute, this is the temperature (° C.) indicating the apex of the endothermic peak having the largest endothermic capacity.
(I) The temperature is raised at a rate of 320 ° C./min from a temperature lower than the first endothermic peak of the measurement target component to a temperature at which the measurement target component melts.
(II) Hold at the temperature at which the component to be measured is melted for 2 minutes.
(III) The temperature is lowered to 100 ° C. at a rate of 10 ° C./min. )   The automobile interior / mechanism component according to claim 1, wherein the melt flow rate is 2 to 5 g / 10 min.   The automobile interior / mechanism part according to claim 1 or 2, wherein the automobile interior / mechanism part is at least one selected from the group consisting of a door, a sunroof, a seat belt, a switch, a clip, a seat, and a wiper.   The automobile interior / mechanical part according to any one of claims 1 to 3, wherein the amount of formaldehyde generated calculated by VDA275 is 2 mg / kg or less.   The automobile interior / mechanical part according to any one of claims 1 to 4, wherein the amount of formaldehyde generated calculated by VDA275 is 1 mg / kg or less. Relative to the polyacetal resin (A) 100 parts by mass of any one of claims 1 to 5 the total amount of the hydrazine derivative (B) and the compound (C) is 0.03 to 0.2 parts by weight Automobile interior / mechanism parts according to one item. The automobile according to any one of claims 1 to 6 , wherein a mass ratio ((B) :( C)) between the hydrazine derivative (B) and the compound (C) is 2: 8 to 8: 2. Interior / mechanical parts. The automobile according to any one of claims 1 to 7 , wherein a mass ratio ((B) :( C)) of the hydrazine derivative (B) and the compound (C) is 3: 7 to 7 : 3. Interior / mechanical parts. The automobile interior / mechanism component according to any one of claims 1 to 8 , wherein the polyacetal resin (A) is a polyacetal copolymer. The automobile interior / mechanism component according to any one of claims 1 to 9 , wherein the polyacetal resin (A) is a polyacetal copolymer obtained using methylal as a chain transfer agent.