JP2011231206A - Design component for automobile interior, made of polyacetal resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a design component for automobile interior, made of a polyacetal resin, having excellent mold deposit resistance in a molded product having uneven thickness caused by the embossing applied on the decoration surface and the rib arranged in the molded product, generating a little amount of formaldehyde after successive molding, and excellently reducing the generated amount of the formaldehyde when irradiated with ultraviolet rays (after a weather resistance test).SOLUTION: The design component for the automobile interior, made of the polyacetal resin comprises a polyacetal resin composition obtained from a raw material composition containing a polyacetal resin, a first hydrazine derivative and a compound for decreasing the melting point of the first hydrazine derivative. The mixture of the first hydrazine derivative with the compound for decreasing the melting point of the first hydrazine compound satisfies the conditions represented by the following inequalities, and the polyacetal resin composition contains 0.01-5 pts.mass of a hindered amine-based stabilizer and 0.1-5 pts.mass of an ultraviolet absorber based on 100 pts.mass of the polyacetal resin: (1) T1<T2; and (2) T1<T3.

Description

  The present invention relates to an automobile interior prepared part including a polyacetal resin composition.

  Polyacetal resins have high mechanical strength and rigidity, are excellent in oil resistance and organic solvent resistance, are well balanced in a wide temperature range, and are easy to process. As a gear material, it is often used in OA equipment, digital home appliances, automobile parts, and other industrial parts. However, recently, due to voluntary regulations of automobile manufacturers and parts suppliers, when polyacetal resin is used in automobile interior parts, etc., it is often required to reduce formaldehyde generation in the automobile interior. .

  In order to meet this requirement, in particular to meet the requirement of suppressing the generation of formaldehyde, a method of adding a guanamine and a hydrazide compound to a polyacetal resin composition (for example, see Patent Documents 1 and 5), a method of adding a carboxylic acid hydrazide compound. (For example, refer to Patent Documents 2, 3, and 4), a method of adding a hydrazide compound (for example, refer to Patent Documents 6 and 7), a method of adding an aromatic dihydrazide and an aliphatic hydrazide compound (for example, refer to 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 JP-A-60-83700 JP 59-279896 A JP 2009-155418 A

However, the polyacetal resin composition to which a compound generally referred to as a form catcher as described in the above-mentioned patent document is added has a drawback that the crystallization state of the polyacetal is affected. As a result, the molded article of the conventional polyacetal resin composition has room for improvement from the viewpoint of mold deposit resistance under conditions where the filling rate of the resin into the mold is low.
In particular, in automobile interior prepared parts, the surface of the mold is often subjected to a texture to improve the texture at the design portion, but a mold deposit (hereinafter also referred to as MD) is formed by continuous molding. When it is deposited on the textured surface, there is a problem that the molded product is glossy and the texture is impaired. In addition, since the flow resistance of the resin is increased on the surface of the mold that has been textured, the filling rate of the resin into the mold tends to be low.
In addition, in car interior preparation parts, the product shape is often complicated, and if the ribs are arranged on the molded product or the thickness is not uniform, there will be places where resin filling will deteriorate as a result. MD tends to occur.
On the other hand, in a car interior preparation part, in order to improve the designability, a color pigment or the like may be contained in the polyacetal resin. Recently, as a technique to improve the design characteristics of automotive interior preparation parts, the technique of painting or plating the design surface is known, but it is not efficient from the viewpoint of productivity and economy, and it is not efficient. The load is also regarded as a problem. Therefore, a metallic pigment having a specific particle size and shape ratio (thickness / particle size ratio) to be added to the synthetic resin composition and a resin molded product including the pigment have been proposed (Patent Document 9 and Patent Document 10). reference). In addition, a method of adding a metallic pigment together with a weathering agent and a formaldehyde inhibitor to a polyacetal resin has been proposed (see Patent Document 11).
However, the above-mentioned colored pigments and metallic pigments generally have a problem of increasing the amount of formaldehyde generated during molding by reducing the thermal stability of the molded product. Therefore, when molding a car interior preparation part that requires high designability, there is a problem that MD resistance is not stable, and there is still room for improvement.
In addition, in automobile interior prepared parts, weather resistance is generally required, but the above-mentioned MD is generated in the mold, so that the weather resistance of the molded product after continuous molding is not stable. There is a problem that the amount of formaldehyde generated after the weather resistance test is not stable.

As a result of intensive studies in order to solve the above-mentioned problems, the inventors of the present invention contain 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 one hydrazine derivative and a compound that lowers the melting point of the first hydrazine derivative satisfies a specific condition, and further contains a hindered amine stabilizer and an ultraviolet absorber at a specific ratio The present invention has been completed by finding that automotive interior preparation parts including the above can solve the above problems.
Furthermore, as a result of repeated studies, the present inventors have not only solved the above-mentioned problems when a color pigment or an aluminum pigment is further added to the polyacetal resin composition. It has been found that the effect of improving weather resistance can be obtained.

That is, the present invention is as follows.
[1]
Polyacetal resin,
A first hydrazine derivative;
A compound that lowers the melting point of the first hydrazine derivative;
Automotive interior prepared parts including a polyacetal resin composition obtained from a raw material composition containing
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 the polyacetal resin composition: An automotive interior prepared part including 0.01 to 5 parts by mass of a hindered amine stabilizer and 0.1 to 5 parts by mass of an ultraviolet absorber with respect to 100 parts by mass of the polyacetal resin.
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]
The automotive interior prepared part according to [1] above, including a polyacetal resin composition further containing 0.01 to 10 parts by weight of a color pigment with respect to 100 parts by weight of the polyacetal resin.
[3]
The automotive interior prepared part according to [1] or [2], including a polyacetal resin composition further containing 0.1 to 10 parts by mass of an aluminum pigment with respect to 100 parts by mass of the polyacetal resin.
[4]
Any one of [1] to [3] above, wherein 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. Car interior preparation parts as described.
[5]
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 automobile interior prepared part according to any one of the above [1] to [4].
[6]
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 or The automotive interior prepared part according to any one of the above [1] to [5], which is two or more carboxylic acid hydrazides.

(3)

(In formula (3), R ₁ represents a divalent substituted or unsubstituted hydrocarbon group.)
[7]
Any one of the above [1] to [6], wherein the first hydrazine derivative is one or two or more carboxylic acid dihydrazides selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide and dodecanedioic acid dihydrazide. Car interior preparation parts as described.
[8]
The first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative include different carboxylic acid dihydrazides selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide, [1] to [7] The automotive interior preparation part.
[9]
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. [1] to [8] The automotive interior preparation part.
[10]
Any of [1] to [9] above, wherein the content ratio of the first hydrazine derivative to the compound that lowers the melting point of the first hydrazine derivative is 2: 8 to 8: 2 on a mass basis. This is a car interior preparation part.
[11]
Any of [1] to [10] above, wherein the content ratio of the first hydrazine derivative to the compound that lowers the melting point of the first hydrazine derivative is 3: 7 to 7: 3 on a mass basis. This is a car interior preparation part.
[12]
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 automotive interior prepared part according to any one of the above [1] to [11], which is less than 95% of the peak area.
[13]
The automobile interior prepared part according to any one of the above [1] to [12], wherein the polyacetal resin is a polyacetal copolymer.
[14]
The automotive interior prepared part according to any one of the above [1] to [13], wherein the polyacetal resin is a polyacetal copolymer obtained by chain transfer to methylal.
[15]
The automobile interior preparation parts are used as any one selected from the group consisting of doors, instrumental panels, seats, sunroofs, glove boxes, AT shift mechanisms, assist grips, switches, clips, and wipers. The automotive interior preparation component according to any one of [1] to [14] above.

  According to the present invention, the surface of the design is textured, the ribs are arranged on the molded product, and the molded product is excellent in mold deposit resistance in a molded product having a non-uniform thickness, and formaldehyde is generated after continuous molding. Further, it is possible to provide an automobile interior preparation part made of polyacetal resin that is small in amount and that is excellent in suppressing the amount of formaldehyde generated during ultraviolet irradiation (after a weather resistance test).

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. The schematic shape and dimension of the molded product used for each evaluation in an Example are shown.

  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.

This embodiment will be described.
The car interior preparation parts of this embodiment are
Polyacetal resin,
A first hydrazine derivative;
A compound that lowers the melting point of the first hydrazine derivative;
Automotive interior prepared parts including a polyacetal resin composition obtained from a raw material composition containing
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 the polyacetal resin composition: This is an automotive interior prepared part including 0.01 to 5 parts by mass of a hindered amine stabilizer and 0.1 to 5 parts by mass of an ultraviolet absorber with respect to 100 parts by mass of the polyacetal resin.
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 polyacetal resin composition of the present embodiment includes a polyacetal resin (A), a hydrazine derivative (B), a compound (C) that lowers the melting point of the hydrazine derivative (B), and 100 parts by mass of the polyacetal resin. (D) A polyacetal resin composition obtained from a raw material composition containing 0.01 to 5 parts by mass of a hindered amine stabilizer and (E) 0.1 to 5 parts by mass of an ultraviolet absorber, comprising hydrazine A mixture of the 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). Here, the “raw material composition” means a composition containing the above five components (A) to (E), and the raw material composition is subjected to some treatment (for example, mixing, melting, kneading, etc.). The polyacetal resin composition according to the present embodiment is obtained. However, it is preferable that the polyacetal resin composition obtained by performing any treatment subsequently contains the above five 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 trimer (trioxane) or tetramer (tetraoxane), ethylene oxide, propylene oxide, epichlorohydrin, 1,3-dioxolane and 1,3. Examples thereof include polyacetal copolymers obtained by copolymerizing cyclic ethers such as cyclic formals of glycols or diglycols or cyclic formals, which are one or more comonomers selected from the group consisting of 4-butanediol formal. 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 cross-linked structure obtained by copolymerizing with glycidyl ether may be mentioned.

  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.

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

  Although it does not specifically limit as a polymerization catalyst used when obtaining a polyacetal copolymer by copolymerization, Cationic active catalysts, such as a Lewis' acid, a protonic acid, its ester, or an anhydride, are preferable. 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. Among such cationically active catalysts, boron trifluoride diethyl ether, boron trifluoride di-n-butyl ether, and boron trifluoride di-n-butyl etherate are more 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. When methylal is used, the water content is 100 ppm or less and the methanol content is 1% by mass or less, more preferably, the water content is 50 ppm or less and the methanol content is 0.7% by mass or less. The methylal is preferred.

  The polymerization method of the polyacetal copolymer is not particularly limited, but conventionally known methods, for example, U.S. Pat. No. 30,273,352, U.S. Pat. No. 3,803,094, German Patent No. 1161412, and German Patent Invention No. No. 1495228, German Patent No. 1720358, German Patent No. 3018898, JP-A-58-98322, JP-A-7-70267.

  Japanese Patent Publication No. 55-42085 proposes a trivalent phosphorus compound as a catalyst deactivator that does not need to be washed and removed. In order to obtain a polyacetal copolymer having higher thermal stability, Removal of unstable ends is required.

The polyacetal copolymer obtained by the above polymerization method has a thermally unstable terminal portion (— (OCH ₂ ) _n —OH group). It is preferable to subject the unstable end portion to decomposition and removal.

Examples of the method for decomposing and removing a specific unstable terminal portion (hereinafter simply referred to as “unstable terminal portion removing treatment”) include, for example, at least one quaternary ammonium compound represented by the following general formula (7). In the presence, there may be mentioned a method of heat-treating the polyacetal copolymer in a molten state at a temperature not lower than the melting point of the polyacetal copolymer and not higher than 260 ° C.
[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, The said 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. The alkyl group having 1 to 5 carbon atoms or the hydroxyalkyl group having 2 to 4 carbon atoms is preferable, and at least one of R ¹ , R ² , R ³ , and R ⁴ is a hydroxyethyl group. 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 ⁻ ); Hydrochloric acid salts such as hydrochloric acid, odorous acid and hydrofluoric acid; sulfuric acid (X ⁿ⁻ = HSO ₄ ⁻ , SO ₄ ²⁻ ), nitric acid, phosphoric acid, carbonic acid (X ⁿ⁻ = HCO ₃ ⁻ , CO ₃ ²⁻ ), boric acid (X ⁿ⁻ = B (OH) ₄ ⁻ ), chloric acid, iodic acid, silicic acid, perchloric acid, chlorous acid, hypochlorous acid, chlorosulfuric acid, Oxoacid salts such as amidosulfuric acid, disulfuric acid and tripolyphosphoric acid; thioacid salts such as thiosulfuric acid; formic acid, acetic acid, Propionic acid, butanoic acid, isobutyric acid, pentanoic acid, caproic acid, caprylic acid, capric acid, benzoic acid, carboxylic acid salts such as oxalate. Among these, hydroxide, sulfate, carbonate, borate, and carboxylate are preferable. Among the carboxylates, formate, acetate, and propionate are particularly preferable. Examples of such quaternary ammonium compounds include hydroxy choline formate (trimethyl-2-hydroxyethylammonium formate, triethyl-2-hydroxyethylammonium formate, etc.). One of these quaternary ammonium compounds may be used alone, or two or more thereof may be used in combination. Further, in addition to the quaternary ammonium compound, amines such as ammonia and triethylamine which are known decomposition accelerators for unstable terminals may be used in combination.

The amount of the quaternary ammonium compound used in the 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 above-described unstable terminal portion removal treatment, a polyacetal resin having a formaldehyde generation amount of 100 ppm or less with respect to the amount of the polyacetal resin when heated at 200 ° C. for 50 minutes in a nitrogen atmosphere 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 acid mono Carboxylic acid monohydrazides such as hydrazide, 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, Saturated aliphatic carboxylic acid dihydrazides such as acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, speric acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide; maleic acid dihydrazide Dihydrazides of monoolefinic unsaturated dicarboxylic acids such as fumaric acid dihydrazide and itaconic acid dihydrazide; aromatic carboxylic acid dihydrazides such as isophthalic acid dihydrazide, phthalic acid dihydrazide and 2,6-naphthalenedicarbodihydrazide; pyrohydric acid dihydrazide; Trihydrazides such as trimer acid trihydrazide, cyclohexanetricarboxylic acid trihydrazide, benzenetricarboxylic acid trihydrazide, nitrilotriacetic acid trihydrazide, citric acid trihydrazide; pyromellitic acid tetrahydrazide, naphthoic acid tetrahydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1, Tetrahydrazide such as 4,5,8-naphthoic acid tetrahydrazide; hydrazine or a low polymer having a carboxylic acid lower alkyl ester group Polyhydrazide such as polyhydrazide obtained by reaction with hydrazine hydrate (hydrazine hydrate); carbonic acid 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 polyvalent Mixtures with functional semicarbazides; 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 when it has a plurality of hydrazide groups in the molecule 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 more preferably one or two or more monohydrazides and / or dihydrazides different from the hydrazine derivative (B). The compound (C) when B) is dihydrazide 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 was found to be 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 an aliphatic carboxylic acid dihydrazide, the compound (C) that lowers the melting point of the hydrazine derivative (B) is more preferably a saturated aliphatic carboxylic acid dihydrazide different from the hydrazine derivative (B).

  As a result of various studies on the compound (C) that lowers the melting point of the hydrazine derivative (B) and the hydrazine derivative (B) by the present inventors, a mixture of various carboxylic acid hydrazides in a mass ratio of 1: 1 was obtained. Using a differential scanning calorimeter, it is melted by heating at a heating rate of 2.5 ° C./min, held at the melted temperature for 2 minutes, then cooled to 100 ° C. at a cooling rate of 10 ° C./min, and then heated up It was found that when the temperature was raised again at a rate of 2.5 ° C./min, the melting point of the mixture behaved differently than the melting point of each carboxylic acid hydrazide before mixing.

  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. When the temperature indicated by the apex of the endothermic peak having the largest ΔH is defined as “main peak temperature of melting point”, the main peak temperature of melting point of adipic acid dihydrazide is 171 ° C., the main peak temperature of melting point of sebacic acid dihydrazide is 180 ° C. The main peak temperature of the melting point of diacid dihydrazide was 171 ° C.

  When a 1: 1 mass 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., and ΔH at that time was It was 91% based on the total amount (see FIG. 3). The main peak temperature of the melting point of a 1: 1 mass ratio mixture of adipic acid dihydrazide and dodecanedioic acid dihydrazide was 151 ° C., and ΔH at that time was 98% with respect to the total amount of ΔH. The main peak temperature of the melting point of a 1: 1 mass ratio mixture of sebacic acid dihydrazide and dodecanedioic acid dihydrazide was 144 ° C., and ΔH at that time was 80% with respect to the total amount of ΔH. That is, in these 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 the cooling rate of 10 ° C./min. When the temperature was lowered to 100 ° C. and then heated at a rate of temperature rise of 2.5 ° C./min, it was found that 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) And the said polyacetal resin composition is 0.01-5 mass parts of (D) hindered amine stabilizer 0.01-5 mass parts with respect to 100 mass parts of said polyacetal resins, and 0.1-5 mass of (E) ultraviolet absorbers. In the automotive interior prepared part including the polyacetal resin composition, it has excellent mold deposit resistance and formaldehyde emission after continuous molding. The amount is small, and further found that excellent inhibition of formaldehyde emission at the time of ultraviolet irradiation (after weathering).
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.

  The saturated aliphatic carboxylic acid hydrazide more preferably contains a saturated aliphatic carboxylic acid dihydrazide represented by the following general formula (3).

(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. In particular, when the hydrazine derivative (B) is a saturated aliphatic carboxylic acid hydrazide, the compound (C) 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 different from the hydrazine derivative (B) and / or Saturated aliphatic carboxylic acids, which are effective in lowering the melting point of the hydrazine derivative (B).

  More specifically, the hydrazine derivative (B) and the compound (C) that lowers the melting point of the hydrazine derivative (B) are different from each other selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide. It preferably contains an acid dihydrazide. 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 are preferable. 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 of (B) and (C).

  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 it exceeds 0.2 parts by mass, the mold deposit resistance in the mold tends to decrease in the automobile interior prepared part.

  In addition, 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. It is preferably less than 95% of the peak area.

[Hindered amine stabilizer (D)]
The polyacetal resin composition of the present embodiment contains 0.01 to 5 parts by mass of a hindered amine stabilizer with respect to 100 parts by mass of the polyacetal resin. Examples of the hindered amine stabilizer include piperidine derivatives having a sterically hindered group, and examples include ester group-containing piperidine derivatives, ether group-containing piperidine derivatives, and amide group-containing piperidine derivatives. The polyacetal resin composition of the present embodiment is excellent in mechanical properties such as fluidity, impact resistance of the molded article, and weather resistance (light stability) by including a specific amount of a hindered amine stabilizer. It will be a thing.

Examples of ester group-containing piperidine derivatives include aliphatic acyloxypiperidines, aromatic acyloxypiperidines, aliphatic di- or tricarboxylic acid-bis or tripiperidyl esters, and aromatic di-, tri- or tetracarboxylic acid-bis, tris or tetrakispiperidyl. Examples include esters. Specific examples of the aliphatic acyloxypiperidine include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2, C _2-20 aliphatic acyloxy-tetramethylpiperidine such as 2,6,6-tetramethylpiperidine. Specific examples of the aromatic acyloxypiperidine include C _7-11 aromatic acyloxytetramethylpiperidine such as 4-benzoyloxy-2,2,6,6-tetramethylpiperidine. Specific examples of aliphatic di- or tricarboxylic acid-bis or tripiperidyl esters include bis (2,2,6,6-tetramethyl-4-piperidyl) oxalate, bis (2,2,6,6-tetramethyl- 4-piperidyl) malonate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate Bis (2,2,6,6-tetramethyl-4-piperidyl) adipate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) adipate, bis (1-methyl-2,2, 6,6-tetramethyl-4-piperidyl) adipate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethy -4-piperidyl) sebacate, bis (1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl sepacate, bis (2,2,6,6-tetramethyl-1- ( C _2-20 aliphatic dicarboxylic acid-bispiperidyl esters such as octyloxy) -4-piperidinyl) ester, etc. Specific examples of aromatic di, tri or tetracarboxylic acid-bis, tris or tetraxpiperidyl esters include: Fragrances such as bis (2,2,6,6-tetramethyl-4-piperidyl) terephthalate and tris (2,2,6,6-tetramethyl-4-piperidyl) benzene-1,3,5-tricarboxylate In addition to the above, tetrakis (1, 2, 2, 6, -. Pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate are also exemplified as ester group-containing Biperijin derivatives Incidentally, _{"C a-b"} herein a~b carbon atoms ( a and b are integers.), for example, “C _2-20 ” means that the number of carbon atoms is 2-20.

Examples of ether group-containing piperidine derivatives include C _1-10 alkoxypiperidine, C _5-8 cycloalkyloxypiperidine, C _6-10 aryloxypiperidine, C _6-10 aryl-C _1-4 alkyloxypiperidine, and alkyl. Range oxybispiperidine. Specific examples of C _1-10 alkoxypiperidine include C _1-6 alkoxy-tetramethylpiperidine such as 4-methoxy-2,2,6,6-tetramethylpiperidine, and C _5-8 cycloalkyloxypiperidine. As a specific example, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine may be mentioned. Specific examples of C _6-10 aryloxypiperidine include 4-phenoxy-2,2,6,6-tetramethylpiperidine, and specific examples of C _6-10 aryl-C _1-4 alkyloxypiperidine include 4-benzyloxy-2,2,6,6-tetramethylpiperidine, and specific examples of alkylenedioxybispiperidine include 1,2-bis (2,2,6,6-tetramethyl-4 C _1-10 alkylenedioxybispiperidine such as -piperidyloxy) ethane.

  Examples of the amide group-containing piperidine derivatives include carbamoyloxypiperidine such as 4- (phenylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, and bis (2,2,6,6-tetramethyl-4- Carbamoyloxy-substituted alkylenedioxy-bispiperidines such as piperidyl) hexamethylene-1,6-dicarbamate.

  Examples of hindered amine stabilizers include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, 1,2,3,4- A condensate of butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and tridecyl alcohol, and 1,2,3,4-butanetetracarboxylic acid with 1,2,2, 6,6-Pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- (2,4,8,10-tetraoxaspiro [5,5] undecane) -diethanol High molecular weight piperidine derivative polycondensates such as condensates can also be used.

  In addition, as a hindered amine stabilizer, for example, N, N ′, N ″, N ″ -tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6,6-) Tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, 1- [2- {3- (3,5-di-t-butyl-4) -Hydroxyphenyl) propionyloxy} ethyl] -4- {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, and A reaction product of peroxidized 4-butylamino-2,2,6,6-tetramethylpiperidine and 2,4,6-trichloro-1,3,5-triazine and cyclohexane, , N, N′-ethane-1 2- diylbis and (1,3-propanediamine), include the reaction product of.

  A hindered amine stabilizer is used individually by 1 type or in combination of 2 or more types. In the polyacetal resin composition of the present embodiment, the content of the hindered amine stabilizer is 0.01 to 5 parts by mass, preferably 0.1 to 2 parts by mass, more preferably 100 parts by mass of the polyacetal resin. Is 0.1 to 1.5 parts by mass. By adjusting the content of the hindered amine stabilizer to the above range, the molded product obtained from the polyacetal resin composition can maintain an even better appearance.

[Ultraviolet absorber (E)]
The polyacetal resin composition of this embodiment contains 0.1-5 mass parts ultraviolet absorber with respect to 100 mass parts of polyacetal resin. By including the specific amount of the ultraviolet absorber, the molded article obtained from the polyacetal resin composition has improved weather resistance (light stability). Examples of the ultraviolet absorber include benzotriazole compounds, benzophenone compounds, oxalic acid anilide compounds, and hydroxyphenyl-1,3,5-triazine compounds.

Examples of the benzotriazole compounds include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole, Hydroxyl group and alkyl such as 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-diisoamylphenyl) benzotriazole Benzotriazoles having a group (preferably a C _1-6 alkyl group) and a substituted aryl group; such as 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole Benzotriazoles having a hydroxyl group and an aralkyl group or an aryl-substituted aryl group; 2- (2′-hydroxy-4′-octoxif Yl) hydroxyl group and an alkoxy group (preferably a benzotriazole benzotriazoles include and a C _1-12 alkoxy group) a substituted aryl group. As the benzotriazole compounds, among the above, benzotriazoles having a hydroxyl group and a C _3-6 alkyl group-substituted C _6-10 aryl group (particularly a phenyl group), and a hydroxyl group and a C _6-10 aryl- Benzotriazoles having a C _1-6 alkyl group (particularly a phenyl C _1-4 alkyl group) and a substituted aryl group are preferred.

Examples of the benzophenone compounds include benzophenones having a plurality of hydroxyl groups; benzophenones having a hydroxyl group and an alkoxy group (preferably a C _1-16 alkoxy group). Specific examples of benzophenones having a plurality of hydroxyl groups include di-, tri- or tetrahydroxybenzophenones such as 2,4-dihydroxybenzophenone; hydroxyl groups such as 2-hydroxy-4-benzyloxybenzophenone and hydroxyl-substituted aryl or aralkyl groups. And benzophenones having Specific examples of benzophenones having a hydroxyl group and an alkoxy group include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2 Examples include '-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2-hydroxy-4-methoxy-5-sulfobenzophenone. Among the above, benzophenone compounds include benzophenones having a hydroxyl group and a hydroxyl group-substituted C _6-10 aryl group or a C _6-10 aryl-C _1-4 alkyl group, particularly a hydroxyl group and a hydroxyl group-substituted phenyl. Benzophenones having a C _1-2 alkyl group are preferred.

  Examples of the oxalic acid anilide compound include N- (2-ethylphenyl) -N ′-(2-ethoxy-5-t-butylphenyl) oxalic acid diamide, N- (2-ethylphenyl) -N′-. (2-Ethoxy-phenyl) oxalic acid diamide.

  Examples of the hydroxyphenyl-1,3,5-triazine compound include 2,4-diphenyl-6- (2-hydroxyphenyl) -1,3,5-triazine and 2,4-diphenyl-6- (2 , 4-dihydroxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6 (2-hydroxy-4-ethoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4- Diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3 5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) ) -1,3,5-triazine.

  Content of the ultraviolet absorber in the polyacetal resin composition of this embodiment is 0.01-5 mass parts with respect to 100 mass parts of polyacetal resin, Preferably it is 0.1-2 mass parts, More Preferably it is 0.1-1.5 mass parts.

  Among the above, as the hindered amine stabilizer, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) -sebacate, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- (2,4 , 8,10-tetraoxabis [5,5 ′] undecane) diethanol is particularly preferred, and the UV absorber is more preferably a benzotriazole compound, and 2- [2′-hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole is particularly preferred.

  The polyacetal resin composition of this embodiment contains an ultraviolet absorber and a hindered amine stabilizer, and the ratio of the hindered amine stabilizer to the ultraviolet absorber is 10/90 in the former / the latter (mass ratio). -80/20 is preferable, more preferably 10/90 to 70/30, and still more preferably 20/80 to 60/40.

[Coloring pigment (F)]
It is preferable that the polyacetal resin composition of this embodiment further contains a color pigment. Examples of the color 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.

  The content of the color pigment is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 2 parts by mass, and still more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the polyacetal resin. 5 parts by mass.

[Aluminum pigment (G)]
It is preferable that the polyacetal resin composition of this embodiment further contains an aluminum pigment. The aluminum pigment is preferably one in which aluminum is in the form of particles and has an appropriate oxide film on the surface thereof. When the aluminum pigment has an appropriate oxide film, the high reflectance unique to aluminum can be maintained, and the corrosion resistance and stability over time of the particles can be maintained. Further, the purity of the aluminum pigment of the present embodiment is not particularly limited, but other metals may be contained as impurities or alloy components as long as the effects of the present invention are not hindered. Examples of the impurity or alloy component include Si, Fe, Cu, Mn, Mg, and Zn.

  The aluminum pigment of this embodiment can be produced by a known method. For example, atomized powder, cutting powder, foil powder, vapor-deposited powder, and aluminum powder obtained by other methods are selected in advance by primary classification or the like, and in the presence of a grinding medium containing a grinding aid and a solvent, It is obtained by wet pulverization with a lighter, planetary mill, vibration mill, etc., sieve classification in a wet state, and solid-liquid separation with a filter press or the like. Thereby, the aluminum pigment with very few uneven | corrugated shaped fracture surfaces which exist in flake edge part can be manufactured. The pulverization medium used here is preferably as small as possible because the amount of oxygen contained in the particles increases when excessively added.

  The shape of the aluminum pigment of the present embodiment is not particularly limited as long as the surface is smooth, such as a spherical shape, a columnar shape, or a scale shape. The shape is preferably a scaly shape because the dispersion is good when melt-mixed with the polyacetal copolymer and the particles are not easily damaged or broken. Since the scale-like aluminum pigment is easily and uniformly dispersed in the polyacetal resin composition, the lightness of the molded product can be increased efficiently with a smaller amount of addition.

  The content of the aluminum pigment of the present embodiment is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and still more preferably 0.8 to 100 parts by mass of the polyacetal resin. 3-4 parts by mass. By adjusting the content of the aluminum pigment to the above range, the toughness, which is the mechanical property inherent in the polyacetal resin, is better maintained, and it has a light and shadeless appearance, so that stable lightness can be expressed. It becomes possible.

The aluminum pigment used in the present embodiment preferably contains 4 to 25% by volume of particles having a volume average particle size of 15 to 50 μm and a particle size of 10 μm or less. More preferably, the aluminum pigment contains 6 to 20% by volume of particles having a volume average particle size of 15 to 40 μm and a particle size of 10 μm or less. By adjusting the particle size and particle size distribution of the aluminum pigment to the above range, while maintaining the original mechanical properties of the polyacetal resin, it has excellent aluminum luster and has little color change due to visual angle, resulting in weld performance. An excellent molded product tends to be obtained. Moreover, it exists in the tendency for the fluidity | liquidity of a polyacetal resin composition, and the weather resistance of the molded object obtained to become the more excellent thing. Here, the volume average particle size defined in the present specification indicates a value (D ₅₀ ) of 50% of the volume particle size distribution measured by a laser diffraction particle size distribution analyzer, and the particle size is 10 μm or less. The ratio of the particles to be obtained is obtained from the integral value.

  Moreover, it is preferable that the surface of the aluminum pigment of the present embodiment is modified with a fatty acid having 10 to 30 carbon atoms. The amount of fatty acid used when modifying the surface of the aluminum pigment is preferably 0.3 to 10 parts by mass, more preferably 0.5 to 8 parts by mass with respect to 100 parts by mass of the aluminum pigment. By adjusting the amount of fatty acid used within the above range, the surface of the aluminum pigment can be well modified, the stability when mixed with the polyacetal resin can be improved, and the appearance of the molded body can be improved. Become.

  The fatty acid having 10 to 30 carbon atoms is not particularly limited, but oleic acid, lauric acid, myristic acid, palmitic acid, behenic acid, and stearic acid are preferable, and oleic acid, behenic acid, and stearic acid are more preferable.

  In addition, a small amount of thermosetting resin may be used in combination to assist modification of the surface of the aluminum pigment. Examples of such thermosetting resins include unsaturated polyester resins and epoxy resins.

  The modification of the aluminum pigment surface with a fatty acid is preferably performed by mixing them. At this time, a generally used mixer can be used for mixing the aluminum pigment and the fatty acid and, if necessary, the thermosetting resin. Examples of the mixer include a ribbon blender, a Henschel mixer, and a tumbler mixer. Moreover, in order to modify | reform efficiently the surface of an aluminum pigment, it is preferable that these mixers are apparatuses which can be heated depending on melting | fusing point of the fatty acid to be used. Moreover, it is preferable to implement this mixing on moderate conditions so that the particle size and shape of powdered aluminum may not be broken.

[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 the above 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 Examples thereof include 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, Preferably, calcium dipalmitate, calcium distearate, and magnesium silicate are mentioned.

[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.

[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.

[Crystal nucleating agent]
Examples of the crystal nucleating agent include boron nitride and talc.

[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.

[Dispersant]
The polyacetal resin composition of this embodiment may further contain a dispersant. A polyalkylene glycol is mentioned as a dispersing agent used when the said color pigment is mixed with the said polyacetal resin composition and granulated with an extruder. A typical example of the polyalkylene glycol is polyethylene glycol. Polyethylene glycol is also effective in preventing noise in the sliding form between polyacetal resins. The molecular weight of polyethylene glycol is not particularly limited, but is preferably 5000 to 20000.

[Production Method of Polyacetal Resin Composition]
The method for producing the polyacetal resin composition of the present embodiment is not particularly limited. For example, polyacetal resin (A), hydrazine derivative (B), compound (C), hindered amine stabilizer (D) and ultraviolet absorber (E) are mixed in advance using a Henschel mixer, tumbler, V-shaped blender, etc. Is obtained by a method generally known as a method for producing a polyacetal resin composition, such as melt kneading using a single-screw or multi-screw kneading extruder, etc. Can do. Among them, a method using a twin-screw kneading extruder equipped with a decompression device is preferable. Moreover, without previously mixing the above components (A) to (E), the raw material composition is obtained in the extruder by continuously supplying each component alone or several types together in a quantitative feeder or the like to the extruder, It is also possible to produce a polyacetal resin composition from the raw material composition. In addition, a high-concentration master batch composed of the above components (A) to (E) is prepared in advance, and a polyacetal resin composition is obtained by further diluting with the polyacetal resin (A) at the time of extrusion melt kneading or injection molding. You can also.

  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 an automotive interior prepared part including the polyacetal resin composition of the present embodiment is not particularly limited, and known molding methods such as extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding. , Decorative molding, molding of other materials, gas-assisted injection molding, firing injection molding, low-pressure molding, ultra-thin injection molding (ultra-high-speed injection molding), in-mold composite molding (insert molding, outsert molding), etc. It can shape | mold by either.

The automotive interior prepared part including the polyacetal resin composition of the present embodiment has a mold deposit resistance in a molded product in which a textured surface is applied to the design surface, ribs are arranged on the molded product, and the thickness is not uniform. Excellent formability, less formaldehyde generation after continuous molding, and excellent suppression of formaldehyde generation during UV irradiation.

Next, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to the following examples unless it exceeds the gist.
Measurement and evaluation of various physical properties in the following Examples and Comparative Examples were performed as follows.

(1) Evaluation of resin According to ASTM-D1238, the melt flow rate was measured under the conditions of 190 ° C. and 2169 g, and the polyacetal resins (a-1) to (a-4) described later were obtained from them. It was confirmed that the melt flow rates of the polyacetal resin compositions were the same.

(2) Evaluation mold Assuming a car interior preparation part, it has a box shape with a length of 100mm, a width of 30mm, and a height of 20mm. The evaluation mentioned later was performed using the metal mold | die which gave the rib. FIG. 5 shows the schematic shape and dimensions of the molded product (the unit of dimensions in the figure is mm).

(3) Formaldehyde generation amount (VDA275)
The amount of formaldehyde released from the test piece was determined by the following method (VDA275 method) using the 30th shot of the molded product used for the evaluation of MD properties described later.
Distilled water (50 mL) and a test piece were placed in a 500 mL polyethylene container, sealed, and heated at 60 ° C. for 3 hours. Thereafter, formaldehyde in distilled water was reacted with acetylacetone in the presence of ammonium ions. About the reaction material, the absorption peak of wavelength 412nm was measured with UV spectrometer, and formaldehyde generation amount (mg / kg) was calculated | required.

(4) 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 was set to 180 ° C. and the mold temperature was set to 60 ° C. Under the injection conditions of injection pressure 80 MPa, injection time 40 seconds, cooling time 20 seconds, the polyacetal resin composition made of the polyacetal resin described later is completely put into the mold with the evaluation mold described in (2) above. Molding was performed under conditions that do not allow filling. The mass of this test piece was 97% by mass of the test piece obtained by completely filling the resin composition in the mold. However, when the melt flow rate was different as in the polyacetal resin (a-2), the injection pressure was adjusted so that the weight of the molded product was equivalent.
The mold deposit (MD) in the mold after molding the molded product for 500 shots was visually observed. “A” indicates that no MD was observed, and “C” indicates that a clear precipitate was observed.

(5) Evaluation of weather resistance in samples for MD resistance evaluation Using the molded product obtained in the above-mentioned MD resistance evaluation (4) at the 5th, 100th and 300th shots, under the following conditions: The weather resistance was evaluated.
Using a super xenon weather meter (trade name “XAL-2WL”, manufactured by Suga Test Instruments Co., Ltd.), the rising wavelength is 320 nm, the sample surface light intensity is 162 w / m ² (light intensity control is 300 to 400 nm), and the black panel temperature is 89. The design surface subjected to the embossing of the evaluation sample was irradiated with light under the conditions of 0 ° C. and no light / dark cycle. The time (h) until cracking occurred in the sample for evaluation was measured.

(6) Amount of formaldehyde generated after the weather resistance test Evaluation of MD resistance in the above weather resistance test (5) (4) Same as the above (3), using a sample after 300 shots and an irradiation time of 500 hours In this way, the amount of formaldehyde generated was obtained. However, the amount of formaldehyde generated was not measured for samples in which cracks occurred in the molded product at 500 hours after light irradiation.

[Polyacetal resin composition]
In the examples and comparative examples, the following 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 flow rate 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 flow rate 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 flow rate was 9 g / 10 min. Its melting point was 165 ° C.

<Polyacetal resin (a-3)>
The polyacetal resin (a-3) is obtained in the same manner as the polyacetal resin (a-1) except that methylal (water content: 45 ppm, methanol content: 0.58%) is used instead of methylal as the chain transfer agent. It was. The melt flow rate of the obtained polyacetal resin (a-3) was 9 g / 10 min. 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 by mass of the obtained crude polyacetal, 0.8 part by mass of triphenylphosphine was added and mixed uniformly to obtain a polyacetal resin (a-4). The resulting polyacetal resin (a-4) had a melt flow rate of 9 g / 10 min. 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.

[Hindered amine stabilizer]
(D-1) Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (d-2) 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6 -Condensation product of pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- (2,4,8,10-tetraoxabis [5,5 ′] undecane) diethanol

[Ultraviolet absorber]
(E-1) 2- [2′-Hydroxy-3 ′, 5′-bis (α, α-dimethylbenzyl) phenyl] benzotriazole

[Coloring pigments]
(F-1) Carbon black Trade name: Acetylen Black (manufactured by Denki Kagaku Kogyo Co., Ltd.)
(F-2) Titanium oxide Trade name: TITANIX JR-600A (manufactured by Teika Co., Ltd.)

[Aluminum pigment]
Commercially available scaly aluminum powder was classified to the desired particle size with a Tyler standard sieve to obtain an aluminum pigment. A detailed particle size distribution is measured with a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, trade name “SALD-1100”), and the volume average particle size D of the aluminum pigment is determined by 50% of the obtained particle size distribution. ₅₀ was obtained. Further, the ratio of particles having a particle diameter of 10 μm or less (hereinafter referred to as “a ratio of 10 μm or less”) was determined from the integrated value based on the particle diameter distribution.
The above-mentioned classified aluminum pigment and behenic acid (a ratio of 2 parts by mass of behenic acid to 100 parts by mass of aluminum powder) are mixed for 3 minutes with a ribbon blender (80 ° C, 80 rpm) with a jacket to modify the surface. Aluminum pigments (g-1) and (g-2) were prepared, the aluminum pigments (g-1) and (g-2) were mixed at a predetermined ratio, and aluminum pigments (g-3) to (g-3) to ( g-6) was obtained.
(G-1) Volume average particle diameter D ₅₀ = 23 μm, ratio of 10 μm or less = 0.4 volume% aluminum pigment (g-2) Volume average particle diameter D ₅₀ = 12 μm, ratio of 10 μm or less = 40 volume% Aluminum pigment (g-3) Volume average particle diameter D ₅₀ = 22 μm, 10 μm or less ratio = 6 volume% aluminum pigment (g-4) Volume average particle diameter D ₅₀ = 20 μm, 10 μm or less ratio = 12 volume% Aluminum pigment (g-5) Volume average particle diameter D ₅₀ = 18 μm, ratio of 10 μm or less = 20 vol% aluminum pigment (g-6) Volume average particle diameter D ₅₀ = 16 μm, ratio of 10 μm or less = 25 vol% Aluminum pigment

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

[Examples 1 to 20]
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- 2) and the compound (C) for reducing the melting point of the hydrazine derivative (B) and hydrazine derivative (B) selected from (bc-3), 0.5 part by mass of a hindered amine stabilizer (D), and an ultraviolet absorber 0 0.5 parts by mass (E), 0.2 parts by mass of color pigment (F) and 2 parts by mass of aluminum pigment (G) 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. Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. In addition, the amount of formaldehyde generated in the samples after the weathering test was evaluated. Also, the differential scanning calorific value of the mixture of the hydrazine derivative (B) and the compound (C) that decreases the melting point of the hydrazine derivative (B) used in each example was used. Table 2 shows the main peak temperature of the melting point when subjected to the measurement.

[Comparative Example 1]
Pellets of the polyacetal resin composition were produced by melt-kneading 100 parts by mass of the polyacetal resin (a-1) with a twin screw extruder with a vent. Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.

[Comparative Example 2]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-2) was used instead of the polyacetal resin (a-1). Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.

[Comparative Example 3]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-3) was used instead of the polyacetal resin (a-1). Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.

[Comparative Example 4]
A pellet of the polyacetal resin composition was produced in the same manner as in Comparative Example 1 except that the polyacetal resin (a-4) was used instead of the polyacetal resin (a-1). Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.

[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 types, 0.01-5 mass parts (D) of a hindered amine stabilizer and 0.1-5 mass parts (E) of an ultraviolet absorber 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. Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.
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 differential scanning calorimetry described above. The main peak temperatures of the melting points of the mixture of the two carboxylic acid hydrazides used in Comparative Examples 10 and 11 were 172 ° C. and 168 ° C., respectively.

[Comparative Example 13]
In the ratio shown in Table 2, the melting point of the hydrazine derivative (B) and the hydrazine derivative (B) of the carboxylic acid hydrazide (bc-1) and (bc-2) is reduced to 100 parts by mass of the polyacetal resin (a-1). The compound (C) to be added was 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. Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.

[Comparative Example 14]
In the ratio shown in Table 2, the melting point of the hydrazine derivative (B) and the hydrazine derivative (B) of the carboxylic acid hydrazide (bc-1) and (bc-2) is reduced to 100 parts by mass of the polyacetal resin (a-1). Compound (C) and hindered amine stabilizer 0.01-5 parts by mass (D) 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. Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.

[Comparative Example 15]
In the ratio shown in Table 2, the melting point of the hydrazine derivative (B) and the hydrazine derivative (B) of the carboxylic acid hydrazide (bc-1) and (bc-2) is reduced to 100 parts by mass of the polyacetal resin (a-1). 0.1 to 5 parts by mass (E) of the compound (C) and ultraviolet absorber to be added 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. Using the obtained pellets as described above, evaluation of the formaldehyde generation amount, mold deposit resistance (MD) resistance, and weather resistance of the MD resistance evaluation sample by an evaluation mold assuming an automobile interior preparation part. The formaldehyde generation amount of the sample after the weather test was evaluated.

  The composition of the polyacetal resin compositions of Examples 1 to 20 and the formaldehyde generation amount, the mold deposit resistance (MD) resistance, and the weather resistance of the MD resistance evaluation sample using the evaluation mold assuming the automobile interior prepared parts. Table 2 shows the evaluation results of the formaldehyde generation amount of the samples after the evaluation of the property and the weather resistance test. Table 3 shows the compositions and evaluation results of Comparative Examples 1 to 15.

  From the results shown in the table, the polyacetal resin composition according to the present embodiment has a textured surface on the design surface, a rib is disposed on the molded product, or a non-uniform thickness in the automotive interior prepared part. It can be seen that it is excellent in mold deposit resistance in a molded mold, has a small amount of formaldehyde generated after continuous molding, and is excellent in suppressing the amount of formaldehyde generated during ultraviolet irradiation (after a weather resistance test).

  When the polyacetal resin composition of the present invention is used, it is excellent in mold deposit resistance in a molded product in which a textured surface is applied to the design surface, ribs are arranged on the molded product, or the thickness is not uniform, and continuous molding is performed. Since the amount of formaldehyde generated is small and it is excellent in suppressing the amount of formaldehyde generated when irradiated with ultraviolet rays, it can be suitably used particularly for automobile interior preparation parts.

Claims (15)

Polyacetal resin,
A first hydrazine derivative;
A compound that lowers the melting point of the first hydrazine derivative;
Automotive interior prepared parts including a polyacetal resin composition obtained from a raw material composition containing
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 the polyacetal resin composition: An automotive interior prepared part including 0.01 to 5 parts by mass of a hindered amine stabilizer and 0.1 to 5 parts by mass of an ultraviolet absorber with respect to 100 parts by mass of the polyacetal resin.
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 automotive interior prepared part according to claim 1, further comprising a polyacetal resin composition further containing 0.01 to 10 parts by weight of a color pigment with respect to 100 parts by weight of the polyacetal resin.   The automobile interior prepared part according to claim 1 or 2, comprising a polyacetal resin composition further containing 0.1 to 10 parts by mass of an aluminum pigment with respect to 100 parts by mass of the polyacetal resin.   4. The compound according to claim 1, wherein 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. 5. Automobile interior preparation parts.   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 automobile interior preparation part according to any one of claims 1 to 4. 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 or The automotive interior prepared part according to any one of claims 1 to 5, which is two or more carboxylic acid hydrazides.
(3)
(In formula (3), R ₁ represents a divalent substituted or unsubstituted hydrocarbon group.)   The said 1st hydrazine derivative is 1 type, or 2 or more types of carboxylic acid dihydrazide chosen from the group which consists of adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide, The any one of Claims 1-6. Automobile interior preparation parts.   The first hydrazine derivative and the compound that lowers the melting point of the first hydrazine derivative include different carboxylic acid dihydrazides selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide. Item 8. A car interior preparation part according to any one of items 1 to 7.   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 9. A car interior preparation part according to any one of items 1 to 8.   The content ratio between the first hydrazine derivative and the compound that decreases the melting point of the first hydrazine derivative is 2: 8 to 8: 2 on a mass basis. Car interior preparation parts as described.   The content ratio between 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. Car interior preparation parts as described.   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 automobile interior prepared part according to any one of claims 1 to 11, which is less than 95% of the peak area.   The automotive interior prepared part according to any one of claims 1 to 12, wherein the polyacetal resin is a polyacetal copolymer.   The automobile interior prepared part according to any one of claims 1 to 13, wherein the polyacetal resin is a polyacetal copolymer obtained by chain transfer to methylal.   The automobile interior preparation parts are used as any one selected from the group consisting of doors, instrumental panels, seats, sunroofs, glove boxes, AT shift mechanisms, assist grips, switches, clips, and wipers. The automotive interior prepared part according to any one of claims 1 to 14.