JP5281541B2 - Polyacetal resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyacetal resin composition which is excellent in the dimensional stability after the aging, the repeated impact resistance after the aging, the recyclable moldability, and the mold deposit resistance under a condition of a low filling in a metal mold. <P>SOLUTION: The polyacetal resin composition is obtained from a raw material composition containing a polyacetal resin, a hydrazine derivative and a compound to drop a melting point of the hydrazine derivative, wherein this polyacetal resin composition is configured such that a mixture of the hydrazine derivative and the compound satisfy the conditions of T1&lt;T2 and T1&lt;T3. T1 is a top temperature of an endothermic peak showing the maximal endothermic capacity at a time when the mixture is subjected to heating and chilling at a given thermal program by means of DSC and then the mixture is increased in the temperature at a given rate until the mixture melts; and similarly T2 and T3 are each a top temperature of an endothermic peak showing the maximal endothermic capacity for the hydrazine derivative and the polyacetal resin, respectively. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a polyacetal resin composition.

  Polyacetal resin is excellent in the balance of mechanical strength, chemical resistance and slidability, and easy to process. Therefore, polyacetal resin is used as a typical engineering plastics over a wide range mainly in electrical equipment, mechanical parts of electrical equipment, automobile parts, and other mechanical parts. However, polyacetal resins are required to suppress generation of formaldehyde, have dimensional stability after aging, hot water resistance, and mold deposit resistance due to the expansion of their application fields. In this way, the required level of various performances for polyacetal resins is increasing at present.

  In order to meet these demands, in particular to meet the demand for suppression of formaldehyde generation, a method of adding guanamine and a hydrazide compound to the polyacetal resin composition (see, for example, Patent Documents 1 and 5) and a carboxylic acid hydrazide compound are added. A method (for example, see Patent Documents 2, 3, and 4), a method for adding a hydrazide compound (for example, see Patent Documents 6 and 7), a method for adding an aromatic dihydrazide and an aliphatic hydrazide compound (for example, see Patent Document 8). ) Is being considered.

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 polyacetal resin composition to which a compound generally referred to as a form catcher is added affects the crystallization state of the polyacetal. As a result, the molded article of the polyacetal resin composition is not stable in dimensions, the amount of formaldehyde released during recycling is not stable, and the repeated impact resistance after aging is not stable. Have. Moreover, the polyacetal resin composition has room for improvement in mold deposit resistance under conditions where the hot water resistance and the filling rate into the mold are low.

  Therefore, the present invention has been made in view of the above circumstances, dimensional stability after aging, repeated impact resistance after aging, recycle moldability, that is, formaldehyde emission reduction during recycling, and to mold An object of the present invention is to provide a polyacetal resin composition excellent in mold deposit resistance under a condition where the filling rate of the resin is low.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a polyacetal resin composition containing a polyacetal resin, a hydrazine derivative, and a compound that lowers the melting point of the hydrazine derivative can solve the above problems. The present invention has been completed.
That is, the present invention is as follows.

（式（３）中、Ｒ₁は２価の置換又は無置換の炭化水素基を示す。）
［６］前記第１のヒドラジン誘導体が、アジピン酸ジヒドラジド、セバシン酸ジヒドラジド及びドデカン二酸ジヒドラジドからなる群より選ばれる１種又は２種以上のカルボン酸ジヒドラジドである、［１］〜［５］のいずれか一項に記載のポリアセタール樹脂組成物。
［７］前記第１のヒドラジン誘導体と前記第１のヒドラジン誘導体の融点を低下させる前記化合物とが、アジピン酸ジヒドラジド、セバシン酸ジヒドラジド及びドデカン二酸ジヒドラジドからなる群より選ばれる互いに異なるカルボン酸ジヒドラジドを含む、［１］〜［６］のいずれか一項に記載のポリアセタール樹脂組成物。
［８］前記ポリアセタール樹脂１００質量部に対して、前記第１のヒドラジン誘導体と前記第１のヒドラジン誘導体の融点を低下させる前記化合物との合計の含有量が０．０３〜０．２質量部である、［１］〜［７］のいずれか一項に記載のポリアセタール樹脂組成物。
［９］前記第１のヒドラジン誘導体と、前記第１のヒドラジン誘導体の融点を低下させる前記化合物との含有比が、質量基準で２：８〜８：２である、［１］〜［８］のいずれか一項に記載のポリアセタール樹脂組成物。
［１０］前記第１のヒドラジン誘導体と、前記第１のヒドラジン誘導体の融点を低下させる前記化合物との含有比が、質量基準で３：７〜７：３である、［１］〜［９］のいずれか一項に記載のポリアセタール樹脂組成物。
［１１］前記第１のヒドラジン誘導体と前記第１のヒドラジン誘導体の融点を低下させる前記化合物との質量比１：１の混合物の吸熱容量が最も大きな吸熱ピークのピーク面積が、前記混合物の全吸熱ピークの総ピーク面積の９５％未満である、［１］〜［１０］のいずれか一項に記載のポリアセタール樹脂組成物。
［１２］前記ポリアセタール樹脂が、ポリアセタールコポリマーである、［１］〜［１１］のいずれか一項に記載のポリアセタール樹脂組成物。
［１３］前記ポリアセタール樹脂が、メチラールに連鎖移動させて得られるポリアセタールコポリマーである、［１］〜［１２］のいずれか一項に記載のポリアセタール樹脂組成物。
［１４］［１］〜［１３］のいずれか一項に記載のポリアセタール樹脂組成物を含む自動車内装・機構用成形品。
［１５］ドア、サンルーフ、シートベルト、スイッチ、クリップ、シート及びワイパーからなる群より選ばれる、［１４］に記載の自動車内装・機構用成形品。 [1] A polyacetal resin composition obtained from a raw material composition containing a polyacetal resin, a first hydrazine derivative, and a compound that lowers the melting point of the first hydrazine derivative,
A polyacetal resin composition, wherein a mixture of the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative satisfies the conditions represented by the following formulas (1) and (2).
T1 <T2 (1)
T1 <T3 (2)
(In the formulas (1) and (2), T1 is 2.5 ° C./until the mixture is melted after being heated and cooled with a predetermined temperature program using a differential scanning calorimeter. Among the endothermic peaks obtained when the temperature is increased at a rate of minutes, the temperature (° C.) indicates the peak of the endothermic peak having the largest endothermic capacity, and T2 is the first hydrazine using the differential scanning calorimeter. Among the endothermic peaks obtained when the derivative is heated and cooled by a predetermined temperature program and then heated to a rate of 2.5 ° C./min with respect to the first hydrazine derivative, the endothermic capacity is T3 is the temperature (° C.) indicating the peak of the largest endothermic peak, and T3 is the temperature of the polyacetal resin after heating and cooling the polyacetal resin with a predetermined temperature program using the differential scanning calorimeter. Among the endothermic peak obtained when heated at 2.5 ° C. / min with respect to a temperature (℃) endothermic capacity indicating the vertex of the largest endothermic peak.)
[2] A polyacetal resin composition obtained from a raw material composition containing a polyacetal resin, a first hydrazine derivative, and a compound that lowers the melting point of the first hydrazine derivative,
A mixture of the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative satisfies the conditions represented by the following formulas (1) and (2), and molding of the polyacetal resin composition: A polyacetal resin composition having a tensile elongation retention of 50% or more after subjecting the body to a predetermined hot water test.
T1 <T2 (1)
T1 <T3 (2)
(In the formulas (1) and (2), T1 is 2.5 ° C./until the mixture is melted after being heated and cooled with a predetermined temperature program using a differential scanning calorimeter. Among the endothermic peaks obtained when the temperature is increased at a rate of minutes, the temperature (° C.) indicates the peak of the endothermic peak having the largest endothermic capacity, and T2 is the first hydrazine using the differential scanning calorimeter. Among the endothermic peaks obtained when the derivative is heated and cooled by a predetermined temperature program and then heated to a rate of 2.5 ° C./min with respect to the first hydrazine derivative, the endothermic capacity is T3 is the temperature (° C.) indicating the peak of the largest endothermic peak, and T3 is the temperature of the polyacetal resin after heating and cooling the polyacetal resin with a predetermined temperature program using the differential scanning calorimeter. Among the endothermic peak obtained when heated at 2.5 ° C. / min with respect to a temperature (℃) endothermic capacity indicating the vertex of the largest endothermic peak.)
[3] In the above [1] or [2], the compound that lowers the melting point of the first hydrazine derivative is one or more second hydrazine derivatives different from the first hydrazine derivative. The polyacetal resin composition as described.
[4] The first hydrazine derivative is a carboxylic acid hydrazide, and the compound that lowers the melting point of the first hydrazine derivative is one or more carboxylic acid hydrazides different from the first hydrazine derivative. The polyacetal resin composition according to any one of [1] to [3].
[5] The first hydrazine derivative is a carboxylic acid dihydrazide represented by the following general formula (3), and the compound that lowers the melting point of the first hydrazine derivative is different from the first hydrazine derivative. The polyacetal resin composition according to any one of [1] to [4], which is one or more carboxylic acid hydrazides.

(In formula (3), R ₁ represents a divalent substituted or unsubstituted hydrocarbon group.)
[6] The first hydrazine derivative is one or more carboxylic acid dihydrazides selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide and dodecanedioic acid dihydrazide. The polyacetal resin composition according to any one of the above.
[7] The first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative are different carboxylic acid dihydrazides selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide. The polyacetal resin composition according to any one of [1] to [6].
[8] The total content of the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative is 0.03 to 0.2 parts by mass with respect to 100 parts by mass of the polyacetal resin. The polyacetal resin composition according to any one of [1] to [7].
[9] The content ratio of the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative is 2: 8 to 8: 2 on a mass basis, [1] to [8] The polyacetal resin composition as described in any one of these.
[10] The content ratio of the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative is 3: 7 to 7: 3 on a mass basis, [1] to [9] The polyacetal resin composition as described in any one of these.
[11] The peak area of the endothermic peak having the largest endothermic capacity of the mixture having a mass ratio of 1: 1 between the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative is the total endotherm of the mixture. The polyacetal resin composition according to any one of [1] to [10], which is less than 95% of the total peak area of the peak.
[12] The polyacetal resin composition according to any one of [1] to [11], wherein the polyacetal resin is a polyacetal copolymer.
[13] The polyacetal resin composition according to any one of [1] to [12], wherein the polyacetal resin is a polyacetal copolymer obtained by chain transfer to methylal.
[14] A molded article for automobile interior / mechanism comprising the polyacetal resin composition according to any one of [1] to [13].
[15] The automotive interior / mechanized molded article according to [14], which is selected from the group consisting of a door, a sunroof, a seat belt, a switch, a clip, a seat, and a wiper.

  According to the present invention, dimensional stability after aging, repetitive impact resistance after aging, recyclability, that is, stability of formaldehyde emission during recycling, and resistance under conditions where the filling rate into the mold is low. A polyacetal resin composition excellent in mold depositing property can be provided.

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 which shows the apparatus for evaluating repeated impact resistance with a test piece.

  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.

The polyacetal resin composition of this embodiment is a polyacetal 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 resin composition, wherein the mixture of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) satisfies the conditions represented by the following formulas (1) and (2) It is. Here, the “raw material composition” means a composition containing the above three components, and the raw material composition is subjected to some treatment (for example, mixing, melting, kneading, etc.) and the polyacetal resin according to the present embodiment. A composition is obtained. However, it is preferable that the polyacetal resin composition obtained by performing any treatment subsequently contains the above three components.
T1 <T2 (1)
T1 <T3 (2)

  Here, in the formulas (1) and (2), T1 represents a mixture of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) using a differential scanning calorimeter. Of the endothermic peak with the largest endothermic capacity among the endothermic peaks obtained when the temperature is raised at a rate of 2.5 ° C./min until the mixture melts after heating and cooling in accordance with a predetermined temperature program. T2 is a temperature of 2.5 ° C./min after heating and cooling the hydrazine derivative (B) with a predetermined temperature program using the above differential scanning calorimeter. Among the endothermic peaks obtained when the temperature is raised, this is the temperature (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity, and T3 is a predetermined value for the polyacetal resin (A) using the differential scanning calorimeter. Temperature program After performing heating and cooling without, among the endothermic peak obtained when temperature was raised at 2.5 ° C. / min, the temperature (℃) endothermic capacity indicating the vertex of the largest endothermic peak.

  The above-mentioned “predetermined temperature program” means a rate of 2.5 ° C./min from a temperature lower than the endothermic peak of the mixture, the hydrazine derivative (B), and the polyacetal resin (A) to a temperature at which the mixture melts. Temperature program, and then held at that temperature for 2 minutes, and then lowered to 100 ° C. at a rate of temperature decrease of 10 ° C./min.

[Polyacetal resin (A)]
The polyacetal resin (A) is not particularly limited as long as it is conventionally known, and examples thereof include polyacetal homopolymers and polyacetal copolymers. The polyacetal homopolymer, for example, consists essentially of oxymethylene units obtained by homopolymerizing formaldehyde monomers or cyclic oligomers of formaldehyde such as trimers (trioxane) and tetramers (tetraoxane). A polyacetal homopolymer may be mentioned. Polyacetal copolymers include formaldehyde monomers or cyclic oligomers of formaldehyde such as trimers (trioxane) or tetramers (tetraoxane), ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane, 1, Examples include polyacetal copolymers obtained by copolymerization with cyclic ethers such as glycols such as 4-butanediol formal or diglycol cyclic formals or cyclic formals. 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.

  In addition, 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 formaldehyde and a cyclic ether or cyclic formal. A polyacetal copolymer having a block component is also exemplified as the polyacetal resin (A). As described above, any of a polyacetal homopolymer and a polyacetal copolymer can be used as the polyacetal resin (A). Among these, a polyacetal copolymer is preferable from the viewpoint of a balance between thermal stability and mechanical properties. A polyacetal resin (A) is used individually by 1 type or in combination of 2 or more types.

  In the case of a polyacetal copolymer of trioxane and the above-mentioned comonomer such as 1,3-dioxolane, generally, if the copolymerization ratio of the comonomer is in the range of 0.001 to 0.6 mol with respect to 1 mol of trioxane, heat stability This is preferable because the property is improved. 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 their esters or anhydrides are preferred. Examples of Lewis acids include boric acid, tin, titanium, phosphorus, arsenic and antimony halides. More specifically, boron trifluoride, tin tetrachloride, titanium tetrachloride, phosphorus pentafluoride, Examples thereof include 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. 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. Furthermore, when using methylal, the amount of water content is 100 ppm or less and the amount of methanol contained is 1% by mass or less, more preferably, the methylal content is 50 ppm or less and the amount of methanol contained is 0.7% by mass or less. .

  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 ) _n —OH group). Therefore, in order to improve its practicality, the following specific irregularities are required. It is preferable to disassemble and remove the stable end portion.

  The specific decomposing / removing treatment of unstable terminal portion (hereinafter, simply referred to as “unstable end portion removing treatment”) is, for example, in the presence of at least one quaternary ammonium compound represented by the following general formula (7). In this method, the polyacetal copolymer is heat-treated at a temperature not lower than the melting point of the polyacetal copolymer and not higher than 260 ° C. in a molten state.

[R ¹ R ² R ³ R ⁴ N ⁺ ] _n X ^n- (7)
Here, in formula (7), R ¹ , R ² , R ³ and R ⁴ 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 the substituted or unsubstituted alkyl group having 1 to 30 is substituted with an aryl group having 6 to 20 carbon atoms; at least one hydrogen atom of the 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 general formula (7), but R ¹ , R ² , R ³ , and R ⁴ in the general formula (7) are each independently selected. In addition, the alkyl group is 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 ¹ , R ² , R ³ , and R ⁴ is a hydroxyethyl group. Some are particularly preferred. Specifically, tetramethylammonium, tetoethylammonium, tetrapropylammonium, tetra-n-butylammonium, cetyltrimethylammonium, tetradecyltrimethylammonium, 1,6-hexamethylenebis (trimethylammonium), decamethylene-bis- ( Trimethylammonium), trimethyl-3-chloro-2-hydroxypropylammonium, trimethyl (2-hydroxyethyl) ammonium, triethyl (2-hydroxyethyl) ammonium, tripropyl (2-hydroxyethyl) ammonium, tri-n-butyl ( 2-hydroxyethyl) ammonium, trimethylbenzylammonium, triethylbenzylammonium, tripropylbenzylammonium, tri-n-butylbenzene Such as zirconium ammonium, trimethylphenylammonium, triethylphenylammonium, trimethyl-2-oxyethylammonium, monomethyltrihydroxyethylammonium, monoethyltrihydroxyethylammonium, octadecyltri (2-hydroxyethyl) ammonium, tetrakis (hydroxyethyl) ammonium Hydroxides (X ⁿ⁻ = OH ⁻ ); hydrogenates such as hydrochloric acid, odorous acid, 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, hypochlorous acid, chlorosulfuric acid, Oxoacid salts such as amidosulfuric acid, disulfuric acid, tripolyphosphoric acid; thioacid salts such as thiosulfuric acid; formic acid, acetic acid, propionic acid, butanoic acid, iso 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.). These quaternary ammonium compounds may be used individually by 1 type, and may be used in combination of 2 or more type. 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 heat treatment method is converted to the amount of nitrogen derived from the quaternary ammonium compound represented by the following formula (8) with respect 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.

P × 14 / Q (8)
Here, in Formula (8), P shows the density | concentration (mass ppm) with respect to the polyacetal copolymer of a quaternary ammonium compound, 14 is the atomic weight of nitrogen, Q shows the molecular weight of a 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) according to 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 monoolefinically unsaturated dicarboxylic acids such as fumarate dihydrazide and itaconic acid dihydrazide; aromatic carboxylic acid dihydrazides such as isophthalic acid dihydrazide, phthalic acid dihydrazide and 2,6-naphthalenedicarbodihydrazide; pyrohydric acid dihydrazide; trimer Trihydrazides such as acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, benzenetricarboxylic acid trihydrazide, nitrilotriacetic acid trihydrazide, 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 or hydrazine Polyhydrazide such as polyhydrazide obtained by reaction with hydrazine hydrate (hydrazine hydrate); carbonic dihydrazide; bissemicarbazide; diisocyanate such as hexamethylene diisocyanate and isophorone diisocyanate and polyisocyanate compound derived therefrom, N, N-dimethylhydrazine Polyfunctional semicarbazide obtained by excessively reacting N, N-substituted hydrazine and / or the above-exemplified hydrazide, etc .; including a hydrophilic group such as the polyisocyanate compound and polyether polyols or polyethylene glycol monoalkyl ethers 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; the polyfunctional semicarbazide and the aqueous multifunctional compound A mixture with active semicarbazide; bisacetyldihydrazone and the like.

[Compound (C) that lowers the melting point of the hydrazine derivative (B)]
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. It has been found that the melting point of the hydrazide derivative (B) itself tends to increase and is higher than the melting point of the polyacetal resin (A). Further, it has been found that mold deposits tend to occur when the difference between the melting point of the polyacetal resin (A) and the melting point of the hydrazine derivative (B) increases. Therefore, the present inventors have focused on compounds that lower the melting point of the hydrazine derivative (B).
The compound (C) that lowers the melting point of the hydrazine derivative (B) is not particularly limited as long as the melting point can be lowered by addition to the hydrazine derivative (B). Among them, the compound (C) is preferably one or more hydrazine derivatives different from the hydrazine derivative (B). For example, when the hydrazine derivative (B) is a monohydrazide, the compound (C) is one or more monohydrazides and / or dihydrazides and / or hydrazine derivatives (B) different from the hydrazine derivative (B). The compound (C) is more preferably one or more dihydrazides and / or monohydrazides 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 (B) It is effective in lowering the melting point.

  A preferred combination of the hydrazide derivative (B) and the compound (C) is a combination of dihydrazide compounds, more preferably a combination of saturated aliphatic carboxylic acid dihydrazide compounds, that is, a hydrazine derivative (B) is saturated fat. In the case of the group carboxylic acid dihydrazide, the compound (C) for lowering the melting point of the hydrazine derivative (B) is more preferably a saturated aliphatic carboxylic acid dihydrazide different from the hydrazine derivative (B).

  Examples in which the present inventors have studied various compounds (C) that lower the melting point of the hydrazine derivative (B) and the hydrazine derivative (B) are shown below. The present inventors melted a mixture of various two kinds of carboxylic acid hydrazides in a mass ratio of 1: 1 by heating at a heating rate of 2.5 ° C./min using a differential scanning calorimeter, and the melting temperature. At a rate of temperature decrease of 10 ° C./min to 100 ° C. and then heated again at a rate of temperature increase of 2.5 ° C./min. It was found that the behavior differs from the melting point of acid hydrazide.

  For example, when terephthalic acid dihydrazide was 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 peak was observed at 324 ° C. Similarly, when isophthalic acid dihydrazide was heated, an endothermic peak was observed at 226 ° C. Further, the peak of the endothermic peak was 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 “DSC7”, manufactured by Perkin Elmer Co., Ltd.) was obtained by mixing and pulverizing one carboxylic acid hydrazide or two carboxylic acid hydrazides in a mortar at a mass ratio of 1: 1. The temperature is increased to 200 ° C. at a temperature increase rate of 2.5 ° C./min, held at 200 ° C. for 2 minutes, and then the temperature is decreased to 100 ° C. at a temperature decrease rate of 10 ° C./min. The melting point was measured by raising the temperature at 5 ° C./min and confirming the peak of the endothermic peak.
For example, when adipic acid dihydrazide alone was subjected to differential scanning calorimetry as described above, two endothermic peaks were observed, and melting points were observed at 176 ° C. and 171 ° C. from the peaks. The endothermic capacities (hereinafter referred to as “ΔH”) calculated from the areas of the respective endothermic peaks were 5.4 J / g and 229.2 J / g, respectively. The ratio of ΔH of the endothermic peak showing the melting point of 171 ° C. to the total amount of ΔH, that is, the ratio of the peak area of the endothermic peak showing the melting point of 171 ° C. to the total peak area of those endothermic peaks is 98%. (See FIG. 1). Moreover, when the sebacic acid dihydrazide simple substance was similarly subjected to differential scanning calorimetry, melting points 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 the endothermic peaks indicating the respective melting points with respect to the total amount of ΔH was 10% at 185 ° C., 60% at 180 ° C., and 30% at 172 ° C. (see FIG. 2). Similarly, when dodecanedioic acid dihydrazide alone was measured, melting points were observed at 183 ° C., 177 ° C. and 171 ° C., and ΔH of each was 2.4 J / g, 18.1 J / g and 32.4 J / g. there were. Furthermore, the ratio of ΔH of the endothermic peaks indicating the respective melting points to the total amount of ΔH was 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 herein as the “melting point main peak temperature”. C., the main peak temperature of the melting point of dodecanedioic acid dihydrazide was 171.degree.

  When a 1: 1 mass ratio mixture of adipic acid dihydrazide and sebacic acid dihydrazide was subjected to differential scanning calorimetry as described above, the main peak temperature of the melting point was 154 ° C., where ΔH was the sum of ΔH It was 91% with respect to the amount (see FIG. 3). The main peak temperature of the melting point of the 1: 1 mass mixture of adipic acid dihydrazide and dodecanedioic acid dihydrazide was 151 ° C., where ΔH was 98% relative to the total amount of ΔH. The main peak temperature of the melting point of the 1: 1 mass ratio mixture of sebacic acid dihydrazide and dodecanedioic acid dihydrazide was 144 ° C., where ΔH was 80% relative to the total amount of ΔH. That is, in those mixtures, the above-mentioned mixture having a mass ratio of 1: 1 is melted by heating at a heating rate of 2.5 ° C./min, held at the melted temperature for 2 minutes, and then at a cooling rate of 10 ° C./min. It was found that when the temperature was lowered to 100 ° C. and then raised at a rate of temperature rise of 2.5 ° C./min, a melting point (the end of the endothermic peak) was present.

  On the other hand, when a mixture of sebacic acid dihydrazide and isophthalic acid dihydrazide in a mass ratio of 1: 1 was heated to 250 ° C. at a heating rate of 2.5 ° C./min, an endothermic peak was 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 increased to 250 ° C. at a temperature increase rate of 2.5 ° C./min. Was not observed and did not crystallize 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 melting point (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 melting point (endothermic peak) disappeared when the temperature was raised at 5 ° C./min.

As a result of further studies by the present inventors, it was 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 polyacetal resin composition, wherein the mixture of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) satisfies the conditions represented by the following formulas (1) and (2) Mold deposit resistance under conditions where dimensional stability after aging, repeated impact resistance after aging, recycle moldability, hot water resistance, mold filling rate is low when the polyacetal resin composition is It has been found that a polyacetal resin composition having excellent properties can be obtained.
T1 <T2 (1)
T1 <T3 (2)
Here, in the formulas (1) and (2), T1 is heated and cooled with a predetermined temperature program for a mixture of the hydrazine derivative and a compound that lowers the melting point of the hydrazine derivative using a differential scanning calorimeter. Among the endothermic peaks obtained when the temperature is increased at a rate of 2.5 ° C./min until the mixture is melted, the temperature (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity, T2 is an endothermic peak obtained when the hydrazine derivative (B) is heated and cooled with a predetermined temperature program using the differential scanning calorimeter and then heated at a rate of 2.5 ° C./min. Among these, the temperature (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity, and T3 is heated and cooled with a predetermined temperature program for the polyacetal resin (A) using the differential scanning calorimeter. After performing, among endothermic peaks obtained when temperature was raised at 2.5 ° C. / min, the temperature (℃) endothermic capacity indicating the vertex of the largest endothermic peak. The above-mentioned “predetermined temperature program” means a rate of 2.5 ° C./min from a temperature lower than the endothermic peak of the mixture or hydrazine derivative (B) to a temperature at which the mixture or hydrazine derivative (B) melts. Temperature program, and then held at that temperature for 2 minutes, and then lowered to 100 ° C. at a rate of temperature decrease of 10 ° C./min. In the case of the polyacetal resin (A), the above-mentioned “predetermined temperature program” means that the temperature is raised from a temperature lower than the endothermic peak of the polyacetal resin (A) to 200 ° C. at a rate of 320 ° C./min, and at 200 ° C. for 2 minutes. It means a temperature program that lowers the temperature to 100 ° C. at a rate of 10 ° C./min after being held.

  Preferred hydrazine derivatives (B) from the above studies are saturated aliphatic carboxylic acid hydrazides, specifically, succinic acid monohydrazide, glutaric acid monohydrazide, adipic acid monohydrazide, pimelic acid monohydrazide, and speric acid monohydrazide. Carboxylic acid monohydrazide such as azelaic acid monohydrazide and sebacic acid monohydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, speric acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, etc. The carboxylic acid dihydrazide.

ここで、式中、Ｒ₁は２価の置換又は無置換の炭化水素基を示し、好ましくは炭素数２〜２０のアルキレン基を示す。 It is more preferable that the saturated aliphatic carboxylic acid hydrazide contains a saturated aliphatic carboxylic acid dihydrazide represented by the following general formula (3).

Here, in the formula, R ₁ represents a divalent substituted or unsubstituted hydrocarbon group, preferably an alkylene group having 2 to 20 carbon atoms.

  The compound (C) that lowers the melting point of the hydrazine derivative (B) is not particularly limited as long as it can lower the melting point by addition to the hydrazine derivative (B) as described above. Among them, the compound (C) when the hydrazine derivative (B) is a saturated aliphatic carboxylic acid hydrazide is preferably one or more saturated aliphatic carboxylic acid hydrazides different from the hydrazine derivative (B). . When the hydrazine derivative (B) is a saturated aliphatic carboxylic acid dihydrazide, the compound (C) is preferably one or more saturated aliphatic carboxylic acid dihydrazides and / or saturated different from the hydrazine derivative (B). Aliphatic carboxylic acids, which are effective in lowering the melting point of the hydrazine derivative (B).

  As a more specific example, the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) are selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide. It is preferable to include different carboxylic acid dihydrazides. 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 Adipic acid dihydrazide and / or dodecanedioic acid dihydrazide is preferable. From the viewpoints of dimensional stability after aging, repeated impact resistance after aging, recycle moldability, hot water resistance, and mold deposit resistance under low mold filling conditions, hydrazine derivatives (B ) And the compound (C) having a mass ratio of 1: 1, the main peak area having the largest ΔH is less than 95% of the ΔH of all the peaks. As a combination of such a hydrazine derivative (B) and compound (C), adipic acid dihydrazide as hydrazine derivative (B), a combination of sebacic acid dihydrazide as compound (C), sebacic acid dihydrazide as hydrazine derivative (B), A combination of dodecanedioic acid dihydrazide is preferred as the compound (C).

  The content ratio ((B) :( C)) of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) is from 2: 8 to 8: 2 on a mass basis. Preferably, it is 3: 7-7: 3. When the content ratio is within the above range, the main peak temperature tends to be lower than the melting point of the polyacetal resin (A) for the solidified product of the mixture.

  The total content of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) in the raw material composition for obtaining the polyacetal resin composition of the present embodiment is 100 mass of the polyacetal resin. It is preferable that it is 0.03-0.2 mass part with respect to a part, More preferably, it is 0.04-0.2 mass part, More preferably, it is 0.05-0.2 mass part. If the total content of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) is less than 0.03 parts by mass, the amount of formaldehyde released during recycle molding tends to increase. If the amount is more than 0.2 parts by mass, the mold deposit resistance under conditions where the filling rate into the mold is low and the repeated impact resistance after aging tend to be lowered.

[Additive]
A suitable additive can be mix | blended with the polyacetal resin composition of this embodiment according to a use. Specific examples of the additive include an antioxidant, a polymer or compound having formaldehyde-reactive nitrogen, a formic acid scavenger, and a mold release agent.
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, More preferably, it is 0.01-0.7 mass part. .

[Antioxidant]
As the antioxidant, a hindered phenol antioxidant is preferable. 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], pentaerythritol tetrakis [me Ren-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 the 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 condensates, ethylene urea, hydantoin compounds, and ureido compounds. 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, 5 Dimethylhydantoin, specific examples of the 5,5-diphenylhydantoin and the like. Ureido compounds, specific examples of allantoin and the like. Imide compound succinimide, glutarimide, and phthalimide.

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

[Formic acid scavenger]
The formic acid scavenger is capable of efficiently neutralizing 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, 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 releasing agent, alcohol, fatty acid and fatty acid ester thereof are preferably used, and particularly preferable releasing agent includes ethylene glycol distearate.

[Other additives]
In the polyacetal resin composition of 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 and 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 the powdered inorganic filler include, for example, carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, magnesium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, wollastonite silicate, 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 treatment agent include various coupling treatment 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.

  In addition to / in place of the inorganic filler, a high melting point organic fibrous material such as an aromatic polyamide resin, a fluororesin, or an acrylic resin may be used.

[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 resin coloring, 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.

  In the polyacetal resin composition of the present embodiment, it is preferable that the tensile elongation retention rate of the molded body is 50% or more. The retention of the tensile elongation is measured according to the method described in the following examples. In general, when an additive is used for the polyacetal resin, the compatibility is affected and the hot water resistance is lowered. Therefore, in order to increase the tensile elongation retention ratio to 50% or more, for example, it is necessary to improve the compatibility. As one of the methods, a method of bringing the melting point of the additive close to the melting point of the polyacetal resin can be mentioned. . The polyacetal resin composition using such an additive can provide a molded product in which the decrease in hot water resistance is further suppressed.

[Production Method of Polyacetal Resin Composition]
The method for producing the polyacetal resin composition of the present embodiment is not particularly limited. For example, after a polyacetal resin (A), a hydrazine derivative (B), and a compound (C) are mixed in advance with a Henschel mixer, tumbler, V-shaped blender, etc. to obtain a raw material composition containing them, uniaxial or It can be produced by a method generally known as a method for producing a polyacetal resin composition, such as melt kneading using a multi-screw kneading extruder or the like. Among them, a method using a twin-screw kneading extruder equipped with a decompression device is preferable. In addition, the polyacetal resin (A), the hydrazine derivative (B), and the compound (C) are not mixed in advance, and each component is singly or several types are collected and fed continuously to the extruder with a quantitative feeder or the like. It is also possible to obtain a raw material composition and to produce a polyacetal resin composition from the raw material composition. In addition, by preparing a high-concentration master batch composed of the polyacetal resin (A), the hydrazine derivative (B) and the compound (C) in advance, and further diluting with the polyacetal resin (A) at the time of extrusion melt-kneading or injection molding. A polyacetal resin composition can also be obtained.

  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.

[Molding method of polyacetal resin composition]
The method for molding the polyacetal resin composition 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. The polyacetal resin composition can be molded by any one of molding methods such as (ultra-high speed injection molding) and in-mold composite molding (insert molding, outsert molding).

[Usage]
Since the molded product obtained by molding the polyacetal resin composition of the present embodiment is excellent in molding recyclability, it can be used for molded products for various applications. Examples of such molded products include gears, cams, sliders, levers, arms, clutches, felt clutches, idler gears, pulleys, rollers, rollers, key stems, key tops, shutters, reels, shafts, joints, shafts, bearings. , And mechanical parts such as guides, resin parts for outsert molding, resin parts for insert molding, chassis, trays, side plates, parts for office automation equipment such as printers and copiers, VTR (Video Tape Recorder) , Video movie, digital video camera, camera and camera represented by digital camera, or parts for video equipment, cassette player, DAT, LD (Laser Disk), MD (Mini Disk), CD (Compact Disk: C) -ROM (Read Only Memory), CD-R (Recordable), CD-RW (including Rewriteable), DVD (Digital Video Disk): DVD-ROM, DVD-R, DVD + R, DVD-RW, DVD + RW, DVD-R DL, DVD + R DL, DVD-RAM (including Random Access Memory), DVD-Audio), Blu-ray Disc, HD-DVD, other optical disk drives, MFD, MO, navigation systems, and music represented by mobile personal computers , Parts for communication equipment represented by video or information equipment, mobile phones and facsimiles, parts for electrical equipment, and parts for electronic equipment. Also, automobile parts can be cited as molded articles according to the present embodiment. For example, fuel-related parts such as gasoline tanks, fuel pump modules, valves, gasoline tank flanges, door locks, door handles, window regulators. And door belt parts represented by speaker grills, seat belt slip rings, seat belt peripheral parts represented by press buttons, combination switch parts, switches, and clips. Furthermore, as a molded article according to the present embodiment, for example, a mechanical pencil pen tip and a mechanical part for inserting and removing a mechanical pencil core, a wash basin, a drain outlet, a drain plug opening / closing mechanism part, and a vending machine opening / closing Part locking mechanism, product discharge mechanism parts, cord stopper for clothing, adjuster, and button, nozzle for watering, sprinkling hose connection joint, stair handrail, and building article as a support for flooring, disposable camera , Toys, fasteners, chains, conveyors, buckles, sporting goods, vending machines, furniture, musical instruments, and industrial parts represented by housing equipment. Among them, particularly interior and mechanism parts for automobiles, such as doors, sunroofs, seat belts, switches, clips, seats and wipers are suitable, and more specifically, inside handles / bases, carrier plates, window regulators.・ Pulleys, door latch parts, speaker grills, sunroof parts, press buttons, retractor parts, seat belt adjusters, steering columns, lever controls, cluster clips, ECU cases, curtain airbag clips, assist grip clips, spindle nuts Suitable for seat adjuster parts, lumbar supports, and motor gear parts. However, the molded product is not limited to these.

  The polyacetal resin composition of the present embodiment was excellent in dimensional stability after aging, repeated impact resistance after aging, recycle moldability, hot water resistance, and mold deposit resistance under low filling rate in the mold. It is a resin composition.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, this invention is not limited at all by these. In addition, the measuring method of each physical property is as follows.

<Measurement of dimensional stability (secondary shrinkage) after aging>
Using a polyacetal resin composition described later using an injection molding machine (trade name “SH-75” manufactured by Sumitomo Heavy Industries, Ltd.), the cylinder temperature was set to 200 ° C., the mold temperature was set to 40 ° C., and the injection pressure was 70 MPa. Molding was performed under injection conditions of an injection time of 60 seconds and a cooling time of 15 seconds to obtain an evaluation ISO dumbbell as a polyacetal resin molded product. After completion of molding, the dimension in the flow direction after leaving the dumbbell for 48 hours in an environment of 23 ° C. and 50% humidity is D1 (mm), and after completion of molding, it is 72 hours in an environment of 23 ° C. and 50% humidity. After allowing to stand, the sample is further heated at 120 ° C. for 48 hours and then left at 23 ° C. in an environment of 50% humidity for 48 hours, where D2 (mm) is the dimension in the flow direction. Shrinkage was determined.
Secondary shrinkage (%) = (D1-D2) / die size × 100 (4)

<Measurement of repeated impact resistance after aging>
The evaluation ISO dumbbell obtained as described above was suspended in a gear oven set at 160 ° C. and heated for 240 hours. Thereafter, the dumbbell was taken out from the gear oven and left for 24 hours in a temperature-controlled room maintained at 23 ° C. and 50% humidity. The dumbbell is cut into a long plate shape having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm, and a notch (tip R = 0.25 mm, notch width = 8 mm, notch depth = 2 mm) is formed at the center in the length direction. A test piece was obtained. The obtained test piece was set in a repeated impact resistance measuring device (trade name “AT repeated impact tester” manufactured by Toyo Seiki Seisakusho) as shown by reference numeral 3 in FIG. A weight was set, dropped from a height of 20 mm and collided with a test piece, repeated impacts were given, and the number of impacts (collisions) until the test piece was broken was measured. The greater the number of impacts to failure, the better the repeated impact resistance. In FIG. 5, reference numeral 1 is a preset counter, reference numeral 2 is a drop height adjusting bolt, reference numeral 3 is a test piece, reference numeral 4 is a guide plate, reference numeral 5 is a guide bar, reference numeral 6 is a guide bar presser, and reference numeral 7 is The weight, 8 is a claw, 9 is a stopper, and 10 is a speed adjustment knob.

<Evaluation of recyclability>
Using an injection molding machine (trade name “SH-75” manufactured by Sumitomo Heavy Industries, Ltd.), the cylinder temperature is set to 205 ° C., the mold temperature is set to 70 ° C., the injection pressure is 70 MPa, the injection time is 60 seconds, and the cooling time is set. A predetermined test piece was molded from a polyacetal resin composition described later under an injection condition of 15 seconds. The obtained test piece was pulverized with a V-type pulverizer, and the pulverized product was molded again to obtain a molded product. The amount of formaldehyde released (mg / kg) was derived from a molded product with 5 repeated moldings and a molded product with 10 repeated moldings. The derivation method is shown below.

  The molded product was pulverized with a V-type pulverizer, and the pulverized product was subjected to an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., trade name “SH-75”), cylinder temperature: 220 ° C., injection pressure: (Primary pressure / secondary pressure = 63.7 MPa / 50.0 MPa), injection time: 15 seconds, cooling time: 20 seconds, mold temperature: 77 ° C. Molding was performed to obtain a test piece. The formaldehyde released from the obtained test piece was measured by the following VDA275 method, and the amount was determined as formaldehyde released from the molded product.

  In the VDA275 method, first, 50 mL of distilled water and a test piece of a specified size (length 100 mm × width 40 mm × thickness 3 mm) were accommodated in a polyethylene container and sealed. Next, after heating the container at 60 ° C. for 3 hours, formaldehyde in distilled water was reacted with acetylacetone in the presence of ammonium ions, and the absorption peak at a wavelength of 412 nm was measured with a UV spectrometer for the reaction product. (Mg / kg) was determined.

<Evaluation of hot water resistance>
Using an injection molding machine (trade name “SH-75” manufactured by Sumitomo Heavy Industries, Ltd.), the cylinder temperature is set to 205 ° C., the mold temperature is set to 70 ° C., the injection pressure is 70 MPa, the injection time is 60 seconds, and the cooling time is set. A predetermined test piece was molded from a polyacetal resin composition described later under an injection condition of 15 seconds. The obtained test piece was immersed in a batch-type water bath, a hot water immersion test was performed at 120 ° C. for 20 days, and the sample was taken out from the water bath. About the test piece before and behind a hot water immersion test, the tensile elongation was measured according to ISO527. The case where the tensile elongation retention ratio, which is the ratio of the tensile elongation after the hot water immersion test to the tensile elongation before the hot water immersion test, is 50% or more is evaluated as “A”, and the case where it is less than 50% is evaluated as “B”. It was. This evaluation indicates that the hot water resistance is excellent in the order of “A” and “B”.

<Evaluation of resistance to mold deposit (MD)>
Using an injection molding machine (trade name “IS-100GN” manufactured by Toshiba Machine Co., Ltd.), the cylinder temperature is set to 170 ° C., the mold temperature is set to 60 ° C., the injection pressure is 60 MPa, the injection time is 60 seconds, and the cooling time is 15 A test piece of a flat plate with a thickness of 2 mm and a width of 80 mm × 80 mm was molded from a polyacetal resin composition described below under short injection conditions, that is, a condition in which the resin composition was not completely filled in the mold. . The mass of this test piece was 95% by mass of the test piece obtained by completely filling the resin composition in the mold. The mold deposit (MD) in the mold after 300 shots of the test piece were molded under these conditions was visually observed. “A” indicates that MD is not observed, “B” indicates that MD is slightly observed, and “C” indicates that obvious precipitate is observed. This evaluation shows that MD resistance is excellent in the order of “A”, “B”, and “C”.

[Polyacetal resin composition]
In Examples and Comparative Examples, the following components were used as components contained in 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 at 1.50 × 10 ⁻³ mol with respect to 1 mol of trioxane. Furthermore, polymerization was carried out by continuously adding boron trifluoride di-n-butyl etherate as a polymerization catalyst at 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane. 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 has been deactivated is separated and recovered by filtration with a centrifugal separator. Then, 100 parts by mass of the polyacetal copolymer is choline hydroxide formate (triethyl-2-hydroxyethylammonium formaldehyde) as a quaternary ammonium compound. 1 part by weight of an aqueous solution containing a mate) was added, mixed uniformly, and further dried at 120 ° C. The addition amount of the hydroxycholine formate was adjusted by adjusting the concentration of the hydroxycholine formate in the aqueous solution containing the added choline formate. An amount of choline formate was added in an amount of 20 ppm by mass in terms of the amount of nitrogen derived from the choline formate represented by the above formula (8). 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. Thus, a pelletized polyacetal resin (a-1) was obtained. When the melt index of the obtained polyacetal resin (a-1) was measured according to ASTM-D1238, it was 9 g / 10 min under the conditions of 190 ° C. and 2169 g (the measurement of the melt index is the same hereinafter). Moreover, about polyacetal resin (a-1), it heated up at a speed | rate of 320 degree-C / min to 200 degreeC using the differential scanning calorimeter (The product name "DSC7" by Perkin-Elmer Co., Ltd.), and hold | maintained at 200 degreeC for 2 minutes. Later, the temperature was decreased to 100 ° C. at a rate of 10 ° C./min, and then the melting point (hereinafter the same) measured at a rate of temperature increase of 2.5 ° C./min was 165 ° C.

<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 index was 40 g / 10 minutes. Its melting point was 165 ° C.
<Polyacetal resin (a-3)>
A polyacetal resin (a-3) 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. . Its melting point was 165 ° C.

<Polyacetal resin (a-4)>
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 at 4 kg / hr and 1,3-dioxolane as a comonomer was continuously added at 42.8 g / h (0.039 mol with respect to 1 mol of trioxane). Furthermore, polymerization was carried out by continuously adding boron trifluoride di-n-butyl etherate as a polymerization catalyst at 1.5 × 10 ⁻⁵ mol with respect to 1 mol of trioxane. To 1000 parts of the obtained crude polyacetal, 0.8 part of triphenylphosphine was added and mixed uniformly to obtain a polyacetal resin (a-4). Its melting point was 165 ° C.

<Hydrazine derivative (B) and compound (C) which lowers melting point of hydrazine derivative (B)>
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). These were used as the compound (C) that lowers the melting point of the hydrazine derivative (B) and / or the hydrazine derivative (B).

  Further, after heating and cooling the carboxylic acid hydrazide alone with a predetermined temperature program using a differential scanning calorimeter (trade name “DSC7”, manufactured by Perkin Elmer), 2.5 ° C./min Of the endothermic peaks obtained when the temperature was increased at a rate, the temperature (the main peak temperature of the melting point) (° C.) indicating the peak of the endothermic peak having the largest endothermic capacity was measured. Here, the above-mentioned “predetermined temperature program” means that the temperature is raised at a rate of 2.5 ° C./min from a temperature lower than the endothermic peak of the compound to a temperature at which the compound melts, and then the temperature is maintained for 2 minutes. And then the temperature is lowered to 100 ° C. at a temperature lowering rate of 10 ° C./min. The results are shown in Table 1.

<Antioxidant (D)>
Triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] was prepared as an antioxidant (d).

<Formic acid scavenger (E)>
Calcium distearate was prepared as the formic acid scavenger (e-1), and magnesium silicate was prepared as the formic acid scavenger (e-2).

<Release agent (F)>
Ethylene glycol distearate was prepared as a release agent (f).

<Polymer or compound (G) having formaldehyde-reactive nitrogen>
Nylon 6-6 was prepared as a polymer (g) having formaldehyde-reactive nitrogen.

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

[Examples 1 to 13]
In the proportions shown in Table 2, 100 parts by mass of the polyacetal resin (a-1), (a-2), (a-3) or (a-4) was added to the carboxylic acid hydrazide (bc-1), (bc- The hydrazine derivative (B) selected from 2) and (bc-3) and the compound (C) that lowers the melting point of the hydrazine derivative (B) were added and mixed with a tumbler to obtain a raw material composition. The raw material composition was melt kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition. About the obtained pellet, the measurement of the dimensional stability after aging, the measurement of the impact resistance after aging, the evaluation of recycle moldability, the evaluation of hot water resistance, and the evaluation of MD resistance were performed as described above.
The main peak temperature of the melting point when the mixture of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) used in each example was subjected to the above-mentioned differential scanning calorimetry is shown in Table 2. It was shown to.

[Examples 14 and 15]
To 100 parts by mass of polyacetal resin (a-1), triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant (d) Mass parts and carboxylic acid hydrazides (bc-1) and (bc-2) in the proportions shown in Table 2 were added and mixed with a tumbler to obtain a raw material composition. The raw material composition was melt kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition. About the obtained pellet, the measurement of the dimensional stability after aging, the measurement of the impact resistance after aging, the evaluation of recycle moldability, the evaluation of hot water resistance, and the evaluation of MD resistance were performed as described above.
The main peak temperature of the melting point when the mixture of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) used in each example was subjected to the above-mentioned differential scanning calorimetry is shown in Table 2. It was shown to.

[Example 16]
To 100 parts by mass of polyacetal resin (a-1), triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant (d) A tumbler by adding 0.15 parts by mass of calcium distearate as a formic acid scavenger (e-1) and carboxylic acid hydrazides (bc-1) and (bc-2) in the proportions shown in Table 2 To obtain a raw material composition. The raw material composition was melt kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition. About the obtained pellet, the measurement of the dimensional stability after aging, the measurement of the impact resistance after aging, the evaluation of recycle moldability, the evaluation of hot water resistance, and the evaluation of MD resistance were performed as described above. Table 2 shows the main peak temperature of the melting point when the mixture of the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) was subjected to the differential scanning calorimetry described above.

[Example 17]
To 100 parts by mass of polyacetal resin (a-1), triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant (d) Parts by weight, 0.15 parts by weight of calcium distearate as the formic acid scavenger (e-1), 0.03 parts by weight of ethylene glycol distearate as the release agent (f), Acid hydrazide (bc-1) and (bc-2) were added and mixed with a tumbler to obtain a raw material composition. The raw material composition was melt kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition. About the obtained pellet, the measurement of the dimensional stability after aging, the measurement of the impact resistance after aging, the evaluation of recycle moldability, the evaluation of hot water resistance, and the evaluation of MD resistance were performed as described above. Table 2 shows the main peak temperature of the melting point when the hydrazine derivative (B) and the mixture of the compound (C) that lowers the melting point of the hydrazine derivative (B) were subjected to the differential scanning calorimetry described above.

[Example 18]
To 100 parts by mass of polyacetal resin (a-1), triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant (d) Polymer having 0.15 parts by mass of calcium distearate as a formic acid scavenger (e-1), 0.03 parts by mass of ethylene glycol distearate as a release agent (f), and formaldehyde-reactive nitrogen As (g), 0.05-6 parts by mass of nylon 6-6 and carboxylic acid hydrazides (bc-1) and (bc-2) in the proportions shown in Table 2 were added and mixed with a tumbler to obtain a raw material composition. It was. The raw material composition was melt kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition. The pellets obtained were measured for dimensional stability after aging, repeated impact resistance after aging, evaluation of recycle moldability, evaluation of hot water resistance, and evaluation of MD resistance as described above. Table 2 shows the main peak temperature of the melting point when the hydrazine derivative (B) and the mixture of the compound (C) that lowers the melting point of the hydrazine derivative (B) were subjected to the differential scanning calorimetry described above.

[Example 19]
To 100 parts by mass of polyacetal resin (a-1), triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) -propionate] 0.3 as an antioxidant (d) A polymer containing 0.01 parts by mass of magnesium silicate as a formic acid scavenger (e-2), 0.03 parts by mass of ethylene glycol distearate as a release agent (f), and formaldehyde-reactive nitrogen ( g) 0.05-6 parts by mass of nylon 6-6 and carboxylic acid hydrazides (bc-1) and (bc-2) in the proportions shown in Table 2 were added and mixed with a tumbler to obtain a raw material composition. . The raw material composition was melt kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition. The pellets obtained were measured for dimensional stability after aging, repeated impact resistance after aging, evaluation of recycle moldability, evaluation of hot water resistance, and evaluation of MD resistance as described above. Table 2 shows the main peak temperature of the melting point when the hydrazine derivative (B) and the mixture of the compound (C) that lowers the melting point of the hydrazine derivative (B) were subjected to the differential scanning calorimetry described above.

[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. The pellets obtained were measured for dimensional stability after aging, repeated impact resistance after aging, evaluation of recycle moldability, evaluation of hot water resistance, and evaluation of MD resistance as described above.

[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). The pellets obtained were measured for dimensional stability after aging, repeated impact resistance after aging, evaluation of recycle moldability, evaluation of hot water resistance, and evaluation of MD resistance as described above.

[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). The pellets obtained were measured for dimensional stability after aging, repeated impact resistance after aging, evaluation of recycle moldability, evaluation of hot water resistance, and evaluation of MD resistance as described above.

[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). The pellets obtained were measured for dimensional stability after aging, repeated impact resistance after aging, evaluation of recycle moldability, evaluation of hot water resistance, and evaluation of MD resistance as described above.

[Comparative Examples 5 to 12]
One part of carboxylic acid hydrazide (bc-1), (bc-2), (bc-4) and (bc-5) in a proportion shown in Table 3 in 100 parts by mass of polyacetal resin (a-1) Two raw materials were added and mixed with a tumbler to obtain a raw material composition. The raw material composition was melt kneaded at 200 ° C. with a vented twin-screw extruder to produce pellets of a polyacetal resin composition. The pellets obtained were measured for dimensional stability after aging, repeated impact resistance after aging, evaluation of recycle moldability, evaluation of hot water resistance, and evaluation of MD resistance as described above. The main peak temperature of the melting point of the carboxylic acid hydrazide used alone in Comparative Examples 5 and 12 was 171 ° C. in Comparative Example 5 and 180 ° C. in Comparative Example 12. In Comparative Examples 6 to 9, there was no main peak temperature of the melting point when the mixture of the two carboxylic acid hydrazides used was subjected to the above-mentioned differential scanning calorimetry. Table 3 shows the main peak temperature of the melting point of the mixture of the two carboxylic acid hydrazides used in Comparative Examples 10 and 11.

  Tables 2 and 3 show the compositions of the polyacetal resin compositions of Examples 1 to 19 and Comparative Examples 1 to 12, evaluation of dimensional stability after aging, evaluation of repeated impact resistance after aging, recycle moldability, Table 4 shows the results of evaluation of formaldehyde emission from the molded article, evaluation of hot water resistance and evaluation of MD resistance.

  From the results shown in the table, the polyacetal resin composition according to the present invention is excellent in secondary shrinkage, mold deposit resistance under conditions where the mold filling rate is low, hot water resistance, and repeated impact resistance after aging. It turns out that it is a thing. Moreover, since the molded article which consists of the polyacetal resin composition of this invention is maintaining the formaldehyde discharge | release amount after recycle shaping | molding at the outstanding low level, it turns out that it has the very outstanding recycle moldability.

  As described above, the present invention has a balance of mechanical properties of a polyacetal resin, and has a low dimensional stability after aging, repeated impact resistance after aging, recyclability, hot water resistance, and a low filling rate in a mold. Therefore, it can be suitably used in fields such as automobiles, electrical electronics, and other industries.

Claims (8)

A polyacetal resin, a first hydrazine derivative, a compound that lowers the melting point of the first hydrazine derivative (T2 in the following formula (1)), an alkali metal or alkaline earth metal hydroxide, inorganic acid A polyacetal resin composition obtained from a raw material composition containing a salt, carboxylate or alkoxide,
The polyacetal resin is a polyacetal copolymer, and melts at a temperature not lower than the melting point of the polyacetal copolymer and not higher than 260 ° C. in the presence of at least one quaternary ammonium compound represented by the following general formula (7). A polyacetal resin that has been heat-treated in the state of
[R ¹ R ² R ³ R ⁴ N ⁺ ] _n X ^n- (7)
(In the formula (7), R ¹ , R ² , R ³ and R ⁴ are each independently a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; an aryl group having 6 to 20 carbon atoms; An aralkyl group in which at least one hydrogen atom of a substituted or unsubstituted alkyl group of -30 is substituted with an aryl group having 6 to 20 carbon atoms; at least one hydrogen atom of the aryl group having 6 to 20 carbon atoms is carbon number 1 represents an alkylaryl group substituted with a substituted or unsubstituted alkyl group having 1 to 30. The substituted or unsubstituted alkyl group is linear, branched, or cyclic, and 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, and the hydrogen atom of the unsubstituted alkyl group, aryl group, aralkyl group, or alkylaryl group may be substituted with a halogen atom. N represents an integer of 1 to 3. X represents a hydroxyl group, a carboxylic acid having 1 to 20 carbon atoms, a hydrogen acid other than hydrogen halide, an oxo acid, an inorganic thioacid, or an organic thioacid having 1 to 20 carbon atoms. Indicates an acid residue.)
The first hydrazine derivative is a carboxylic acid hydrazide, and the compound that lowers the melting point of the first hydrazine derivative is one or more hydrazine derivatives different from the first hydrazine derivative;
A mixture of the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative satisfies the conditions represented by the following formulas (1) and (2) ;
A polyacetal resin composition, wherein the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative contain different carboxylic acid dihydrazides selected from the group consisting of adipic acid dihydrazide and sebacic acid dihydrazide .
T1 <T2 (1)
T1 <T3 (2)
(In the formulas (1) and (2), T1 is 2.5 ° C./until the mixture is melted after being heated and cooled with a predetermined temperature program using a differential scanning calorimeter. Among the endothermic peaks obtained when the temperature is increased at a rate of minutes, the temperature (° C.) indicates the peak of the endothermic peak having the largest endothermic capacity, and T2 is the first hydrazine using the differential scanning calorimeter. Among the endothermic peaks obtained when the derivative is heated and cooled by a predetermined temperature program and then heated to a rate of 2.5 ° C./min with respect to the first hydrazine derivative, the endothermic capacity is T3 is the temperature (° C.) indicating the peak of the largest endothermic peak, and T3 is the temperature of the polyacetal resin after heating and cooling the polyacetal resin with a predetermined temperature program using the differential scanning calorimeter. Among the endothermic peak obtained when heated at 2.5 ° C. / min with respect to a temperature (℃) endothermic capacity indicating the vertex of the largest endothermic peak.)   The amount of the alkali metal or alkaline earth metal hydroxide, inorganic acid salt, carboxylate or alkoxide is 0.01 to 0.7 parts by mass relative to 100 parts by mass of the polyacetal resin. 2. The polyacetal resin composition according to 1. The total content of the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative is 0.03 to 0.2 parts by mass with respect to 100 parts by mass of the polyacetal resin. Item 3. The polyacetal resin composition according to Item 1 or 2 . Wherein the first hydrazine derivative, containing ratio of the compound for lowering the melting point of the first hydrazine derivative is 2 by weight: 8 to 8: 2, any one of claims 1 to 3 The polyacetal resin composition described in 1. Wherein the first hydrazine derivative, containing ratio of the compound for lowering the melting point of the first hydrazine derivative, by weight 3: 7 to 7: 3, any one of claims 1-4 The polyacetal resin composition described in 1. The peak area of the endothermic peak having the largest endothermic capacity of the mixture having a mass ratio of 1: 1 between the first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative is the total of all the endothermic peaks of the mixture. The polyacetal resin composition according to any one of claims 1 to 5 , which is less than 95% of the peak area. An automotive interior / mechanized molded article comprising the polyacetal resin composition according to any one of claims 1 to 6 . The molded article for automobile interior / mechanism according to claim 7 , selected from the group consisting of a door, a sunroof, a seat belt, a switch, a clip, a seat, and a wiper.

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