KR20110099994A - Polyoxymethylene resin composition and molded articles manufactured therefrom - Google Patents

Abstract

The present invention provides a polyoxymethylene resin composition having excellent slidability and a low amount of formaldehyde gas released during processing, and a molded article produced therefrom. Specifically, the polyoxymethylene resin composition of the present invention is 100 parts by weight of polyoxymethylene resin having a formic acid ester end group less than 1% by weight; 0.1 to 10 parts by weight of the polyether-ester block copolymer, 0.1 to 5 parts by weight of the olefin copolymer; 0.01 to 5 parts by weight of a polyoxymethylene resin having a crosslinked structure; and 0.01 to 2 parts by weight of a hydrazide compound.
The polyoxymethylene resin composition as described above has excellent wettability, and extremely low formaldehyde gas emission during work forming, so that a high degree of wettability is required and can be usefully applied to the production of environmentally regulated parts and the like. .

Description

Polyoxymethylene Resin Composition and Molded Articles Manufactured Therefrom}

The present invention relates to a polyoxymethylene resin composition having a low amount of formaldehyde gas discharge and excellent in slidability and a molded article produced therefrom.

Polyacetal resins are widely used in the field of automotive electronics because of their excellent mechanical and frictional wear characteristics. Among them, polyoxymethylene resins have excellent fatigue resistance and are mainly used as mechanical parts such as gears. Since the plastic materials used for such mechanical parts are frequently in contact with each other, or between plastic and metal parts, excellent sliding properties are required.

On the other hand, while polyoxymethylene (Polyoxymethylene) resin has excellent mechanical and frictional wear characteristics as described above, there is a problem that formaldehyde (formaldehyde) gas with a pungent odor is generated during the molding process.

Therefore, in recent years, attention has been focused on research and development for improving the slidability of polyoxymethylene resin and reducing the amount of formaldehyde gas generated during molding. In this regard, in order to improve wear friction properties, Japanese Patent Laid-Open No. 2-138357 discloses a composition in which a special graft copolymer and a lubricant are added to a polyacetal resin. For the purpose of improving the impact resistance of polyacetal resins, Japanese Patent Application Laid-Open No. 51-64560 discloses a composition in which a polyether ester block copolymer is blended with a polyacetal resin, and Japanese Patent Laid-Open No. 59-64654. Discloses a composition in which a polyacetal resin is blended with an olefin-based copolymer, which is a glycidyl ester of α-olefin and α, β unsaturated acid. However, in the case of the above-described compositions, the impact resistance was improved to some extent, but the improvement of the slidability including the wear friction characteristics and the reduction of the formaldehyde gas generation amount did not improve the problem.

On the other hand, various methods for reducing the amount of formaldehyde (formaldehyde) gas during the processing molding of the polyoxymethylene resin have also been disclosed. One of them is a method of using additives such as amines and amides which can react with formaldehyde gas due to pyrolysis. Specifically, Japanese Patent Laid-Open No. 4-34563 discloses a method of adding an acrylamide and a boric acid compound to a polyoxymethylene resin, and Japanese Patent Laid-Open No. 59-213752 discloses a method of adding an alanine compound to a polyoxymethylene resin. have. However, all of the above-described methods have a problem of poor workability due to not only a problem of yellowing resin due to decomposition of thermally unstable additives, but also mold ejection during molding due to surface migration due to lack of compatibility between additives and resins.

On the other hand, another method proposed to improve the thermal stability of polyoxymethylene resin is to stabilize the end of the unstable polyoxymethylene, a method of capping the unstable end of the polyoxymethylene with a specific material to be. Specifically, US Patent No. 2,964,500, Japanese Patent Publication No. 42-8706, Japanese Patent Publication No. 33-6099 proposed esterification of polyoxymethylene ends, Japanese Patent Publication No. 35-6233, Japanese Patent Publication So 36-3492 proposed a method of urethanization by reacting unstable hydroxy ends with isocyanates. However, these methods have a problem that the main chain of the polyoxymethylene resin can be easily broken by solvolisys, and the instability of the polymer due to the unreacted capping polymer present at the resin end.

In order to solve the problems of the prior art, the present invention provides a polyoxymethylene resin composition excellent in slidability and low in the amount of formaldehyde gas released.

The present invention also provides a molded article prepared from the above and the polyoxymethylene resin composition.

The present invention 100 parts by weight of polyoxymethylene resin having a formic acid ester terminal group less than 1% by weight; 0.1 to 10 parts by weight of the polyether-ester block copolymer, 0.1 to 5 parts by weight of the olefin copolymer; It provides a polyoxymethylene resin composition comprising 0.01 to 5 parts by weight of a polyoxymethylene resin having a crosslinked structure; and 0.01 to 2 parts by weight of a hydrazide compound.

The present invention also provides a molded article made of the polyoxymethylene resin composition as described above.

Hereinafter, the present invention will be described in more detail.

The polyoxymethylene resin composition has excellent mechanical properties and has been widely used in parts materials such as gears. However, in order to be used as a part material such as a gear, there is a recent technical problem that requires a higher degree of slidability including the wear resistance friction characteristics, and also to reduce the amount of formaldehyde gas of an irritating odor during processing molding Has been.

Accordingly, the present inventors completed the present invention while repeatedly researching a polyoxymethylene resin composition which can minimize the amount of formaldehyde gas generated during molding, and exhibits excellent slidability and also maintains existing excellent mechanical properties.

Such a polyoxymethylene resin composition according to an embodiment of the present invention is 100 parts by weight of polyoxymethylene resin having less than 1% by weight of the formic acid ester end group; 0.1 to 10 parts by weight of the polyether-ester block copolymer, 0.1 to 5 parts by weight of the olefin copolymer; 0.01 to 5 parts by weight of a polyoxymethylene resin having a crosslinked structure; and 0.01 to 2 parts by weight of a hydrazide compound.

The polyoxymethylene resin having a polyether ester block copolymer, an olefin copolymer, and a crosslinked structure in a specific weight ratio to the polyoxymethylene resin having less than 1% by weight of the formic acid ester terminal group as described above. The resin composition blended with not only has excellent slidability including abrasion friction properties, but can also reduce formaldehyde gas emission to a minimum during molding processing.

In this case, the polyoxymethylene resin having less than 1% by weight of the formic acid ester terminal group may be a homopolymer composed of only oxymethylene repeating units, or cyclic acetal copolymerized with oxymethylene repeating units. However, in order to improve slidability including abrasion resistance and friction resistance, it is preferable that oxymethylene repeating unit is included in 90 mol% or more. In addition, the polyoxymethylene resin having less than 1% by weight of the formic acid ester end group may be selected without limitation in the constitution, as long as the content of the formic acid ester end group is less than 1% by weight. Preferably, in order to optimize the values of abrasion resistance and mechanical properties, one having a melt index value of 1.0 to 60 measured according to ASTM D-1238 method (load condition of 190 ° C and 2160 g) is used. Can be. On the other hand, the content of the formic acid ester end group of the polyoxymethylene resin can be measured through the weight loss of the polyoxymethylene resin at 240 ℃, N ₂ atmosphere.

On the other hand, the polyether-ester block copolymer is preferably a copolymer of a hard segment containing polybutylene terephthalate and a soft segment containing poly (tetramethylene oxide) terephthalate.

In the case of using the copolymer of the soft segment and the hard segment having the repeating unit as described above, the wear resistance and friction resistance are excellent, and the mechanical properties including the tensile strength are excellent. More preferably, 30 to 80% by weight of the soft segment including poly (tetramethylene oxide) terephthalate and most preferably 50 to 75% by weight of the soft segment may be used.

On the other hand, in the polyether-ester block copolymer, both the hard segment containing the polybutylene terephthalate and the soft segment containing the poly (tetramethylene oxide) terephthalate are polyesters of a dicarboxylic acid component and a diol component. A copolymer containing unit, Specifically, Aromatic dicarboxylic acid, such as terephthalic acid, isophthalic acid, a phthalic acid, naphthalene-2, 6- dicarboxylic acid, diphenyl-4,4'- dicarboxylic acid, and 3-sulfon isophthalic acid; And at least one dicarboxylic acid component selected from alicyclic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, azelic acid, sebacin, dodecanoic acid and dimer acid, and 1,4-butanediol, ethylene glycol, diethyl glycol At least one diol selected from propylene glycol, 1,6-hexadiol, 1,10-decadiol, 1,4-dihydroxymethyl cyclohexane, bis (4-hydroxyethoxyphenyl) methane and neopentyl glycol The component may be in a form including a copolymerized repeating unit.

At this time, the hard segment containing the polybutylene terephthalate preferably contains at least 70 mol% or more of the terephthalic acid component with respect to 100 mol% of the total dicarboxylic acid component, and the diol component is 1,4- It is preferable that butanediol is contained at least 50 mol% or more with respect to 100 mol% of all diol components at least.

In addition, the soft segment including the poly (tetramethylene oxide) terephthalate preferably contains at least 70 mol% or more of the terephthalic acid component with respect to 100 mol% of the total dicarboxylic acid component, and the diol component is hard. It is possible to use those as exemplified above for the segment and preferably contain at least 30 mol% or more relative to 100 mol% of the total diol component. In addition, the poly (tetramethylene oxide) glycol constituting the poly (tetramethylene oxide) terephthalate repeating unit of the soft segment in order to optimize the wear resistance and friction resistance property has a number average molecular weight of 800 to 20,000, more preferably a number Those having an average molecular weight of 5,000 to 15,000 can be used.

Meanwhile, the polyether-ester block copolymer may further include one or more reactive groups, and by using the polyether-ester block copolymer including such reactive groups, compatibility with the remaining resin composition may be enhanced. And the abrasion resistance and frictional properties of the entire resin composition can be improved. At this time, the reactive group may preferably use an aromatic dicarboxylic acid, specifically, a phthalic acid functional group, a terephthalic acid functional group, an isophthalic acid functional group and trimellitic acid. (trimellitic acid) functional group, and pyromellitic acid (pyromellitic acid) functional group may be one or more selected from, but is not limited to the examples described above.

In addition, the polymerization method of the polyether ester block copolymer is not particularly limited, and may be prepared by a known method. In addition, in the polyoxymethylene resin composition according to the embodiment described above, the addition ratio of the polyether-ester block copolymer is 0.1 to 10 parts by weight based on 100 parts by weight of the polyoxymethylene resin having less than 1% by weight of the formic acid ester terminal group. In order to improve the wear resistance and friction resistance without affecting the mechanical strength, it may be added within the numerical range described above. More preferably, 1 to 5 parts by weight based on 100 parts by weight of the polyoxymethylene resin having less than 1% by weight of the formic acid ester terminal group.

In addition, the olefin copolymer is not limited in its configuration, but preferably is a copolymer of α-olefin, n-alkyl acrylate, and glycidyl ester of α and β unsaturated acids. Can be. In this case, the α-olefin may be ethylene, propylene, butene-1, or the like, and preferably ethylene. In addition, the n-alkyl acrylate may be ethyl acrylate (n-ethyl acrylate), propyl acrylate (n-propyl acrylate), n-butyl acrylate (n-butyl acrylate), and the like, preferably n-butyl N-butyl acrylate. In addition, the glycidyl ester of the α, β unsaturated acid (glycidyl ester) is not limited in configuration, but may preferably be a compound represented by the following formula (1).

Formula 1

However, in Formula 1, R is an alkyl group having 1 to 10 carbon atoms, alkoxy, aryl group, aryloxyalkyl group, or aryloxy group.

Among these, glycidyl acrylate (glycidyl), glycidyl methacrylate (glycidyl), methacrylate glycidyl (glycidyl) and the like can be used.

Further, in the polyoxymethylene resin composition according to the above embodiment, the polyoxymethylene resin having a crosslinked structure is ethylene oxide, propylene oxide, 1,3-dioxolane, 1, Oxy and one or more compounds selected from the group consisting of 3-dioxane, 1,3-dioxepan, 1,3,5-trioxane, 1,3,6-trioxocane, and epicurolhydrin Methylene (oxy methylene), and the copolymer of the repeating unit represented by the following formula (2); And it may be a form containing one or more selected from the group consisting of oxy methylene and a copolymer of a repeating unit represented by the following formula (2).

Formula 2

However, in Formula 2, m and n are integers of 0 to 20, m + n is an integer of 1 or more, and R is an alkyl group having 1 to 10 carbon atoms, an alkoxy, aryl group, aryloxyalkyl group, or aryloxy group.

In this case, the repeating unit represented by Formula 2 is generated from a cyclic ether selected from phenyl glycidyl ether, styrene oxide, and naphthyl glycidyl ether. It may be. On the other hand, the polyoxymethylene resin having such a crosslinked structure is 0.01 to 5% by weight based on 100 parts by weight of the polyoxymethylene resin having less than 1% by weight of the formic acid ester terminal group in order to prevent distortion after molding and impart an impact strength of more than a suitable level Parts may be included, and may preferably include 0.1 to 2 parts by weight.

On the other hand, in the polyoxymethylene resin composition according to the above embodiment, the hydrazide compound may preferably use an aliphatic hydrazide compound. Specifically, hydrazide piopionate, thiocarbohydrazide, dihydrazide oxalate, dihydrazide malonate, dihydrazide succinate, dihydrazide glutarate, dihydrazide adipate, dihydrazide seba Cali, dihydrazide dodecanoic acid, aliphatic consisting of 1,18-octadecane dicarbohydrazide, dihydrazide maleate, dihydrazide fumarate and 7,11-octadecanediene-1, 18-dicarbohydrazide Although it can select from the hydrazide compound group, it is not limited to the above-mentioned example. Meanwhile, in addition to the aliphatic hydrazide compounds described above, dihydrazide compounds may also be used, specifically, dihydrazide adipate, dihydrazide sebacate, dihydrazide dodecanedic acid, dihydrazide terephthalate, and dihydra One or more selected from the group consisting of zide terephthalate may be used, but is not limited to the examples described above.

On the other hand, such a hydrazide compound is 100 weight of polyoxymethylene resin having less than 1% by weight of the formic acid ester terminal group in order to minimize the amount of formaldehyde gas emitted during the molding process of the polyoxymethyl resin composition, and at the same time minimize the color change of the resin 0.01 to 2 parts by weight may be included, and preferably 0.05 to 0.3 parts by weight.

On the other hand, the resin composition according to the above-described embodiment may further include an additive that can be added to the resin composition in a range that does not prevent the achievement of the object of the present invention. Specifically, it may further include one or more additives selected from the group consisting of antioxidants, weathering agents, release agents, colorants, sunscreens, fillers, plasticizers, adhesion aids, and pressure-sensitive adhesives.

Examples of such additives include sterically hindered phenolic, phosphine thioether or amine antioxidants, benzophenone or sterically hindered amine weathering agents, releasing agents such as fluorine-containing polymers, or silicone oils, metal salts of stearyl acids, Metal salts of montanic acid, colorants (dyes or pigments) such as montanic acid ester waxes or polyethylene waxes, sunscreens such as titanium oxide or carbon black, reinforcements such as glass fibers, carbon fibers or potassium titanate fibers, silica, clay, calcium carbonate , Fillers such as calcium sulfate or glass beads, nucleating agents such as talc or clay, plasticizers, adhesion aids, or pressure-sensitive adhesives. It can also be added.

In addition, such a polyoxymethylene resin composition exhibits excellent slidability including abrasion resistance and excellent mechanical properties, and at the same time, a small amount of formaldehyde gas released during molding.

Specifically, the polyoxymethylene resin composition according to the above-described embodiment of the present invention, the coacetal K300 of Kolon plastic as a relative material, the specific wear amount measured under the conditions of a linear speed of 30cm / s and a load of 30N 0.3mm ³ / It is Nkm or less. In addition, the polyoxymethylene resin composition according to the above-described embodiment has a copper friction coefficient of 0.2 or less, and it can be seen that the slidability including wear resistance and friction resistance is very excellent.

On the other hand, the mechanical strength is also excellent, specifically, the polyoxymethylene resin composition according to the above-described embodiment has a tensile strength of 550 kgf / cm ² or more measured according to the method of ASTM D-638. In addition, the amount of formaldehyde gas emitted during the molding process was also minimized, specifically, the amount of formaldehyde generated measured according to the VDA-275 method is less than 1 ppm.

On the other hand, the present invention provides a molded article made of a resin composition according to the above-described embodiments according to another embodiment. When forming the resin composition according to the above-described embodiment for the production of such a molded article, the amount of formaldehyde gas having a toxic and irritating odor is small and easy to work, and the final molded article includes tensile strength and the like. The mechanical properties are excellent, and the slidability including the wear resistance and frictional properties is excellent, and it is expected that the present invention can be usefully applied to the production of molded articles such as gears or cams.

The polyoxymethylene resin composition of the present invention has excellent wettability, and extremely low formaldehyde gas emission during work forming, so that a high degree of wettability is required and can be usefully applied to the production of environmentally regulated parts and the like. .

Hereinafter, the following examples will be described in more detail. However, the following examples are provided to more easily understand the present invention, but the present invention is not limited to these examples.

< Example  1>

100 parts by weight of a polyoxymethylene resin having a melt index of 9.0 g / 10 min and a formic acid ester end group of less than 1% by weight was dried at 80 ° C. under vacuum for 4 hours, and then 4 parts by weight of a polyether-ester block copolymer having a reactive group, PE 2 parts by weight of an acrylate / glycidyl ester copolymer, 1 part by weight of a polyoxymethylene resin having a crosslinked structure, and 0.2 part by weight of a hydrazide compound, followed by blending, and the blend was introduced into a twin screw extruder at 190 ° C. After sufficiently kneading, the mixture was discharged into a spaghetti state through a die, cooled, and cut into chips using a pelletizer. After drying the chip prepared in this way, the molded article was manufactured by injection molding in the form of a specimen for measuring the physical properties at 190 ℃. The composition content ratio of the polyoxymethylene resin and the like used in the blend is as shown in Table 1 below.

< Example  2 to 4>

Except blended with different weight content ratios of polyether-ester block copolymers having reactive groups, PE / acrylate / glycidyl ester copolymers, crosslinked polyoxymethylene resins, and hydrazide compounds It carried out in the same manner as in Example 1 above. The composition of a specific resin composition is as showing in following Table 1.

< Comparative example  1 to 7>

Instead of polyoxymethylene resin (K300LO) having formic acid ester end groups of less than 1% by weight, Kolon Plastic's cooxytal K300 polyoxymethylene resin is used (Comparative Example 1), some of the remaining compositions are not included, or the content ratio is The same method as in Example 1 was carried out except for different points. The composition of a specific resin composition is as showing in following Table 1.

(A) (B) (C) (D) (E) (A-1) (A-2) Example 1 100 4 2 One 0.2 Example 2 100 2 4 One 0.15 Example 3 100 4 2 4 0.15 Example 4 100 7 One 0.5 0.2 Comparative Example 1 100 4 2 One 0.2 Comparative Example 2 100 4 2 One - Comparative Example 3 100 4 2 - 0.2 Comparative Example 4 100 4 - - 0.2 Comparative Example 5 100 11 2 One 0.02 Comparative Example 6 100 - 2 One 0.15 Comparative Example 7 100 5 10 One 0.15

(week)

(A-1) Polyoxymethylene resin (K300LO) having formic acid ester terminal group less than 1% by weight

(A-2) Polyoxymethylene resin (Cortal K300 of Kolon Plastic)

(B) Polyether-ester block copolymer having a reactive group (Kolon Plastic KP3335HR)

(C) Ethylene / acrylate / glycidyl ether copolymer (Dupont elvaloy)

(D) Polyoxymethylene resin having a crosslinked structure (Kolon Plastic)

(E) Dihydrazide (Fine chemical N-12)

<Test method>

One. Polyoxymethylene  Formic acid ester of resin Terminal group  Content measurement

The content of formic acid ester end group of the polyoxymethylene resin was measured by weight loss of the resin at 240 ° C. and N ₂ atmosphere. As a result of the measurement, the content of formic acid ester end groups contained in the polyoxymethylene resins used in Examples 1 to 4 and Comparative Examples 2 to 8 was 0.8% by weight, and the ester contained in the polyoxymethylene resin used in Comparative Example 1. The content of the terminal group was 2.5 to 3.0% by weight.

2.Measure the mechanical characteristics

Using an injection molding machine with an injection capacity of 60 tons, ASTM dumbbell test specimens and friction coefficient-wear-free specimens were molded at a cylinder temperature of 190 ° C., a mold temperature of 80 ° C., and a molding cycle of 40 seconds.

One) The tensile strength  Measure

Tensile strength was measured according to the method of ASTM D-638. The results are shown in Table 2 below.

2) dynamic friction coefficient and Non-wear amount  Measure

The dynamic friction coefficient and the amount of wear were measured by a Suzuki friction wear tester (OFMENT, EFM-III-E). weight; 30 N, linear velocity; 30 cm / s, time: 30 minutes, measurement temperature; 23 degreeC and the counterpart material used the thing injected into the cylindrical shape of general polyoxymethylene resin (KOLON PLASTIC make, brand name KOCETAL K300) with an inner diameter of 20 mm and a contact area of 2.0 cm <^2> .

The dynamic friction coefficient and the wear rate are values calculated from the following equation.

[Equation]

Dynamic Friction Coefficient = f / W (f: Friction, W: Load kgf)

Abrasion wear = V / Wvt (V: frictional capacity, W: load, v: speed, t: _time_)

(The weight and specific gravity of the test material before and after the test were measured and determined from V calculated from this.)

3. Formaldehyde generation measurement ( VDA -275 law)

50 ml of distilled water was put into a l-liter polyethylene bottle, and 80 mm x 40 mm x 3 mm sized injection test pieces were suspended from contact with distilled water and sealed to prevent air from passing through. After leaving at 60 ° C. for 3 hours, 10 ml of distilled water contained in a PET bottle was collected, and 10 ml of acetyl acetone and 10 ml of ammonium acetate were added to measure color change using absorbance. , The amount of formaldehyde generated according to the absorbance was measured. Formaldehyde content measured is shown in Table 2 below.

The tensile strength
(kgf / cm ² ) Dynamic friction coefficient Non-wear amount
(mm ³ / Nkm) Formaldehyde
Content (ppm) Example 1 556 0.15 0.25 0.7 Example 2 560 0.2 0.3 0.6 Example 3 575 0.17 0.29 0.9 Example 4 550 0.19 0.28 0.8 Comparative Example 1 560 0.16 0.24 13 Comparative Example 2 557 0.15 0.25 10 Comparative Example 3 554 0.2 0.44 0.3 Comparative Example 4 582 0.26 0.64 0.4 Comparative Example 5 482 0.3 0.78 3.5 Comparative Example 6 604 0.28 0.98 0.5 Comparative Example 7 454 0.41 0.75 0.8

As shown in Table 2, the specimens of Examples 1 to 4 all exhibit a tensile strength value of at least 550 kgf / cm ² or more, a coefficient of friction coefficient of 0.2 or less, and a wear rate of 0.3 mm ³ / N · km It is excellent in mechanical properties and slidability below. In addition, it was confirmed that the measured formaldehyde content also appeared to be all lower than the comparative examples.

On the other hand, in the specimens of Comparative Examples 1 to 7, it was difficult to find a specimen that satisfies both mechanical properties and slidability such as low tensile strength value or large coefficient of friction coefficient and wear value. In addition, in some specimens, formaldehyde content was also released by more than 10 times compared to the embodiment, it was found that it is not suitable to be used as environmentally regulated parts or indoor vehicle parts.

From the results of such experiments, the polyoxymethylene resin composition according to the embodiments of the present application can be usefully applied to industrial fields related to environmentally regulated parts such as parts requiring high mechanical properties and slidability, and at the same time, indoor parts. It is expected to be able.

Claims (6)

100 parts by weight of polyoxymethylene resin having less than 1% by weight of formic ester terminal group;
0.1 to 10 parts by weight of polyether-ester block copolymer;
0.1 to 5 parts by weight of the olefin copolymer;
0.01 to 5 parts by weight of polyoxymethylene resin having a crosslinked structure; and
Polyoxymethylene resin composition comprising 0.01 to 2 parts by weight of the hydrazide compound. The method of claim 1,
The polyoxymethylene resin having less than 1% by weight of the formic acid ester terminal group contains 90 mol% or more of oxymethylene repeating units, and has a melt index value of 1.0 to 60 g /, measured at 190 ° C and 2160 g according to ASTM D-1238. Polyoxymethylene resin composition which is 10min. The method of claim 1,
The olefin copolymer is a polyoxymethylene resin composition which is a copolymer of α-olefin, n-alkyl acrylate, and glycidyl esters of α and β unsaturated acids. The method of claim 1,
The hydrazide compound is hydrazide piopionate, thiocarbohydrazide, dihydrazide oxalate, dihydrazide malonate, dihydrazide succinate, dihydrazide glutarate, dihydrazide adipate, dihydra Gide sebacide, dihydrazide dodecanoic acid, 1,18-octadecane dicarbo hydrazide, dihydrazide maleate, dihydrazide fumarate, 7,11-octadecanediene-1, 18-dicarbohydrazide, At least one polyoxymethylene resin composition selected from the group consisting of dihydrazide adipate, dihydrazide sebacate, dihydrazide dodecanedic acid, dihydrazide terephthalate, and dihydrazide terephthalate. The method of claim 1,
A polyoxymethylene resin composition having a wear rate of 0.3 mm ³ / N · km or less and a copper coefficient of friction of 0.2 or less, measured under conditions of a linear speed of 30 cm / s and a load of 30 N, using a coacetal K300 of Kolon Plastic as a counterpart. The method of claim 1,
A polyoxymethylene resin composition having a tensile strength of 550 kgf / cm ² or more measured according to the method of ASTM D-638 and a formaldehyde generation amount measured according to the VDA-275 method of less than 1 ppm.