KR101694904B1 - Polyoxymethylene Resin Composition and Molding Including the Same - Google Patents

Abstract

The present invention relates to a polyoxymethylene resin composition applicable to electrical and electronic equipment components and a molded article comprising the same. More particularly, the present invention relates to a polyoxymethylene resin composition comprising a polyacetal resin, a polyether-ester block copolymer, a polyurethane- Polyethylene maleic anhydride phosphoric acid copolymer, and carboxylic acid dihydrazide compound, and a molded article comprising the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyoxymethylene resin composition and a molded article containing the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyoxymethylene resin composition applicable to electrical and electronic equipment parts and molded articles containing the same.

Polyacetal resins are widely used in the field of electric and electronic fields in automobiles because they have well-balanced mechanical properties and excellent friction and wear characteristics. However, it has a disadvantage that it has a high hardness due to its high crystallinity. In order to improve the Brittle property of POM, a method of adding an impact modifier has been studied. Particularly, since POM has no reactive group, studies for improving compatibility with an impact modifier have been actively conducted.

In addition, if the self-lubricating property improves the flexibility of the POM having excellent abrasion resistance compared to other resins, the mechanical properties are deteriorated and a method for solving such problems is required. Also, it is required to have less generation of formaldehyde gas, which is the biggest problem of polyoxymethylene resin.

A method of mixing a hydrocarbon rubber containing a nitrile group or a carboxylic acid ester group (Japanese Examined Patent Publication 45-12674), a method of adding an? -Olefin /?,? - unsaturated carboxylic acid (Japanese Examined Patent Publication No. 45-18023), a method of mixing a copolymer of ethylene / vinyl or acrylic ester (Japanese Examined Patent Publication No. 45-26231), a method of mixing a diolefin / (PN 3,476,832), a method of mixing an aliphatic polyether (Japanese Patent Publication No. 50-33095), an α-olefin polymer and an ethylene / α-olefin copolymer by mixing a copolymer having a hydrocarbon main chain substituted with a nitrile group to improve impact strength and flexural modulus A method of mixing a copolymer of a vinyl monomer (Japanese Patent Laid-Open Publication No. 49-40346), a method of mixing a polyolefin, polystyrene, polyester, and polyamide thermoplastic elastomer (JP-A-60-104116). However, such a method has a problem that the impact strength can not be greatly improved due to the lack of compatibility with the POM.

In order to impart higher toughness, a method of mixing a thermoplastic polyurethane as an elastomer in a Canadian patent 84-2325 is proposed, and Japanese Patent 4183622 proposes a method using a thermoplastic polyurethane / maleic anhydride-containing compound. In Japanese Patent Laid-Open No. 59-145243, a method of mixing a special elastomeric polyurethane to improve compatibility with POM has been proposed. However, this method does not improve the impact properties and formaldehyde gas generation simultaneously.

 In addition, various methods are proposed to reduce the generation of formaldehyde gas. A method of using additives such as amines, amides and the like capable of reacting with formaldehyde gas due to pyrolysis, which is one of them, is proposed. Japanese Patent Application Laid-Open No. 4-34563 proposes a method of adding acrylamide and a boronic acid compound to a POM resin, and JP-A-59-213752 proposes a method of adding an alanine compound to a POM resin. However, these methods not only cause the yellowing of the resin due to the decomposition of the thermally unstable additive, but also cause the mold ejection during molding due to the lack of compatibility of the additive with the resin.

As another method for improving the thermal stability of the POM resin, a method of capping the unstable terminal of the POM using a specific substance has been proposed as a method of stabilizing the terminal of the unstable POM. In US Patent No. 2,964,500, Japanese Patent Publication No. 42-8706, and Japanese Patent Publication No. 33-6099, the terminal of POM is induced to esterify. In Japanese Patent Publication No. 35-6233 and Japanese Patent Publication No. 36-3492, And a method of reacting a hydroxy terminal with an isocyanate to form urethane. These methods have the problem that the main chain of the POM resin can easily be destroyed by solvolisys, and a very unstable polymer can be obtained due to the remaining unreacted capping polymer at the end.

The polyoxymethylene resin having an unstable terminal is difficult to be melt-kneaded with the thermoplastic polyurethane used for improving the impact property, and the compatibility is poor and the impact is difficult to be improved.

The present invention relates to a polyoxymethylene resin composition having excellent mechanical properties and electrical properties and applicable as a machine tool material, and a molded article comprising the same.

Accordingly, the present invention provides, as a first preferred embodiment, 0.1 to 5 parts by weight of a polyether-ester block copolymer per 100 parts by weight of a polyacetal resin; 5 to 50 parts by weight of an ester-based thermoplastic polyurethane elastomer; 0.1 to 5 parts by weight of a modified polyethylene maleic anhydride copolymer; And 0.05 to 2 parts by weight of a carboxylic acid hydrazide compound.

In the polyacetal resin according to the embodiment, the amount of the terminal group of the formic acid ester in the polyacetal resin may be 1% by weight or less.

The thermoplastic polyurethane elastomer according to the embodiment may be an ester-based thermoplastic polyurethane elastomer having a Shore hardness of 55 to 90A.

The content of maleic anhydride in the modified polyethylene maleic anhydride copolymer according to the embodiment may be 0.5 to 3 parts by weight.

The polyoxymethylene resin composition according to this embodiment may have a formaldehyde emission of 2 ppm or less as measured by the VDA 275 method.

The present invention also provides, as a second preferred embodiment, a molded article comprising the polyoxymethylene resin composition.

Since the polyoxymethylene resin composition of the present invention is excellent in mechanical properties, abrasion-resistance and formaldehyde gas release characteristics, it can be used in parts such as gears and cams in interior parts and exhibit excellent effects.

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

The present invention relates to a polyacetal resin composition comprising 0.1 to 5 parts by weight of a polyether-ester block copolymer per 100 parts by weight of a polyacetal resin; 5 to 50 parts by weight of an ester-based thermoplastic polyurethane elastomer; 0.1 to 5 parts by weight of a modified polyethylene maleic anhydride copolymer; And 0.05 to 2 parts by weight of a carboxylic acid hydrazide compound, based on the total weight of the polyoxymethylene resin composition.

In the present invention, mixing of a polyether ester block copolymer with respect to a polyacetal resin is important, whereby a resin composition excellent in not only wear-friction but also excellent release properties of formaldehyde gas can be obtained .

As the polyacetal resin to be used in the present invention, a homo polymer consisting of a chain of oxymethylene units and a homopolymer having a chain of oxymethylene units and being free of a small amount of cyclic ether, Acetal copolymers in which cyclic acetal is copolymerized can all be used. Although the polymerization degree and the like are not limitable, it is preferable that the melt index (MI) value measured at 190 ° C under a load of 2160 g is in the range of 1.0 to 60 according to ASTM D-1238.

The amount of the terminal group of the formic acid ester of the polyacetal resin is preferably 1% by weight or less. When the amount of the formic acid ester terminal group is more than 1% by weight, the formaldehyde gas is continuously released over time after the molding of the product, which lowers the formaldehyde property.

The polyether-ester block copolymer in the present composition is a polyether-ester block copolymer derived from a copolymer having a soft segment constituting a hard segment composed of a dicarboxylic acid component and a glycol component and a soft segment and a reactive group constituting a poly (tetramethylene oxide) terephthalate unit Block copolymers are used. A block copolymer having a soft segment composed of a hard segment mainly composed of a dicarboxylic acid component and glycol component composed of butylene terephthalate units and a poly (tetramethylene glycol) terephthalate unit and a reactive group to be.

The dicarboxylic acid component constituting the hard segment is composed of terephthalic acid alone, or 70 wt% or more of terephthalic acid and 30 mol% or less of isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, , 4'-dicarboxylic acid and 3-sulfonic isophthalic acid, and / or an alicyclic dicarboxylic acid such as oxalic acid, succinic acid, adipic acid, azelic acid, sebacic acid, dodecanoic acid and dimeric acid. Particularly preferred among these copolymerization components are isophthalic acid, adipic acid, sebacic acid and dodecanoic acid.

  The glycol component constituting the hard segment preferably consists of 1,4-butanediol alone, or at least 50% by weight of 1,4-butanediol and not more than 50% by weight of ethylene glycol, diethyl glycol, propylene glycol, 1,6 - at least one copolymerizable component selected from the group consisting of hexadiol, 1,10-decadiol, 1,4-dihydroxymethylcyclohexane, bis (4-hydroxyethoxyphenyl) methane and neopentyl glycol This mixture is used.

  The dicarboxylic acid component constituting the soft segment is mainly composed of terephthalic acid. The dicarboxylic acid component of the soft segment, such as the dicarboxylic acid component of the hard segment, may be comprised of terephthalic acid alone or may comprise not less than 70 wt% of terephthalic acid and not more than 30 wt% of dicarboxylic acid as a copolymerization component. As the copolymerization component, those exemplified above for the hard segment can be used.

The poly (tetramethylene oxide) glycol constituting the soft segment poly (tetramethylene oxide) terephthalate unit preferably has a number average molecular weight of 800 to 20,000, more preferably 5,000 to 15,000. The molecular weight of the poly (tetramethylene oxide) glycol is preferably 2,000 or more, particularly 5,000 or more, from the viewpoint of friction-wear characteristics.

The dicarboxylic acid component constituting the reactive group is composed of an aromatic dicarboxylic acid. Aromatic dicarboxylic acid which is a reactive group is phthalic acid, terephthalic acid and isophthalic acid, and trimellitic acid and pyrolytic acid are preferable in the present invention.

In the polyether-ester block copolymer used in the present invention, a preferable composition ratio between a hard segment composed mainly of butylene tereate units and a soft segment composed mainly of poly (tetramethylene oxide) carboxylate units is poly (tetramethylene oxide) carboxyl The content of the rate unit is preferably 30 to 80% by weight, more preferably 50 to 75% by weight. When the content of the poly (tetramethylene oxide) carboxylate unit is larger than 80% by weight, the polyether-ester block copolymer is hardly polymerized and the mechanical strength of the composition is lowered.

The method for producing the polyether-ester block copolymer of the present invention is not particularly limited, and it is usually produced by a known method. The degree of polymerization is not particularly limited, and the composition of the present invention can be used as long as it can be molded.

In the present invention, the amount of the polyetherester block copolymer to be added is 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the polyacetal resin. If the amount of the polyetherester block copolymer added is less than 0.1 part by weight, miscibility will be insufficient and if the amount is more than 5 parts by weight, mechanical strength will be significantly impaired, which is not preferable.

Examples of the polyurethane-based elastomer used in the present invention include a diisocyanate such as 4,4'-diphenylmethane diisocyanate and 4,4'-dicyclohexylmethane diisocyanate as a hard segment, a glycol such as ethylene glycol and tetramethylene glycol , A soft segment such as a polyester diol such as polyethylene adipate or polybutylene adipate, polypropylene glycol, polyether diol such as polytetramethylene glycol, or the like. The method for producing the polyurethane elastomer of the present invention is not particularly limited and is usually produced by a known method.

In the present invention, the addition amount of the thermoplastic polyurethane elastomer is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the polyacetal resin. When the addition amount of the thermoplastic polyurethane elastomer is less than 5 parts by weight, the physical properties of the impact strength are remarkably impaired. When the addition amount exceeds 50 parts by weight, the mechanical strength is remarkably impaired, which is not preferable.

The modified polyethylene maleic anhydride copolymer used in the present invention is formulated to improve compatibility. A commercially available example of a modified polyethylene maleic anhydride copolymer is Fusabond MF 416D from Du-Dow. This is a copolymer of ethylene and propylene and 1 weight% of maleic anhydride is grafted.

The content of the modified polyethylene maleic anhydride copolymer is 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the polyoxymethylene polymer. If the content of the modified polyethylene maleic anhydride copolymer is less than 0.1 part by weight, it is difficult to melt-knead the POM resin with the polyether-ester block copolymer or the thermoplastic polyurethane on the resin. If it is more than 5 parts by weight, the rigidity is lowered and the economical efficiency is lowered, which is not preferable.

On the other hand, the content of maleic anhydride in the modified polyethylene maleic anhydride copolymer may be 0.5 to 3% by weight. If the amount of the maleic anhydride is out of the range of the maleic anhydride content, the resin is decomposed to increase the mechanical properties and release of formaldehyde gas, .

The carboxylic acid dihydrazide compound used in the present invention can be used as a formaldehyde scavenger and is preferably selected from dihydrazide adipate, dihydrazide sebacate, dihydrazide dodecanedic acid, dihydrazide terephthalate, Dihydrazide terephthalate. ≪ / RTI >

The carboxylic acid dihydrazide may be used alone or in combination of two or more. The amount of the carboxylic acid dihydrazide compound in the composition of the present invention is 0.01 to 2 parts by weight, preferably 0.05 to 0.3 part by weight based on 100 parts by weight of the polyoxymethylene polymer. When the amount of carboxylic acid dihydrazide is less than 0.01 part by weight, the effect of capturing formaldehyde is unsatisfactory. When the amount of carboxylic acid dihydrazide is more than 2 parts by weight, the color is discolored or the effect of capturing formaldehyde is deteriorated.

As long as it does not hinder the achievement of the object of the present invention, conventionally known additives may be added. Examples of such additives include sterically hindered phenol-type, phosphite-type thioether-type or amine-type antioxidants, benzophenone- or hindered amine-type endurance agents, mold release agents such as fluorine-containing polymers, silicone oil, metal salts of stearyl acid, (Dyes or pigments), such as a metal salt of montanic ester wax or polyethylene wax, titanium oxide or carbon black as an ultraviolet screening agent, glass fiber, carbon fiber or potassium titanate fiber as a reinforcing material and silica, clay, Calcium sulfate, or glass beads, and a nucleating agent such as talc, cray, plasticizer, adhesive aid, and pressure-sensitive adhesive.

The polyoxymethylene resin composition according to the present invention improves melt-kneading and improves compatibility, has no swelling phenomenon, improves impact properties, and is excellent in formaldehyde gas release properties. Thus, the impact resistance and the engineering resin .

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. However, the present invention is not limited to the following examples.

Example  1 to 4 and Comparative Example  1 to 7

100 parts by weight of a polyacetal resin (Kosetal K300, Kolon Plastics) having a melt viscosity of 9.0 g / 10 min and a viscosity of 20 g / 10 min was dried at 80 ^° C under vacuum for 4 hours, A thermoplastic polyurethane resin for improving impact, and a carboxylic acid dihydrazide compound as a formaldehyde capturing agent are blended and then they are fed into a twin screw extruder Kneaded sufficiently at 190 ° C, and then discharged in a spaghetti state through a die, cooled, and cut into chips using a pelletizer. The dried chips were dried and then subjected to injection molding at 190 ° C. to prepare molded articles.

Weight loss, mechanical properties and formaldehyde gas emission were measured for the molded articles produced in the following examples and comparative examples in the following manner, and the results are shown in Table 2.

(1) Weight loss measurement: Measure the weight loss at 240 ° C and N ₂ atmosphere.

(2) Mechanical properties: Using an injection molding machine having an injection capacity of 60 tons, ASTM dumbbell specimens and specimens for friction coefficient-non-wear measurement are molded at a mold temperature of 80 ° C and a molding cycle of 40 seconds. Using the tensile test specimens mentioned above, measure the impact strength according to the method of ASTM D-638, and the coefficient of friction - non-wear amount with our measuring method.

(3) Formaldehyde gas emission: Determined by the VDA 275 method. That is, 50 ml of distilled water is put into a 1 liter polyethylene bottle, and a sample of 80 mm x 40 mm x 3 mm is hung so that it does not come in contact with distilled water, and the air is sealed. 10 ml of distilled water treated at 60 ° C for 3 hours was taken and 10 ml of acetyl acetone and 10 ml of ammonium acetate were added to measure the color change of formaldehyde according to the absorbance using the absorbance.

division (a) (b) (c) (d) (e) Example 1 100 One 8 One 0.2 Example 2 100 3 14 3 0.2 Example 3 100 2 16 2 0.2 Example 4 100 3 24 3 0.2 Example 5 100 One 7.5 1.5 0.2 Comparative Example 1 100 0 18.5 1.5 0.2 Comparative Example 2 100 0 17 3.0 0.2 Comparative Example 3 100 3 17 0 0.2 Comparative Example 5 100 0.1 10 0.1 0.2 Comparative Example 6 100 0 8.5 1.5 0 Comparative Example 7 100 0 20 0 0 Comparative Example 8 100 2 16 2 0

(a) Polyacetal resin (KOCETAL K300, Kolon Plastics)

(b) Polyether-ester block copolymer (KOPEL KP3340HR, Kolon Plastics)

(c) a thermoplastic polyurethane resin having a Shore hardness of 80A

(ELLAS K-480A, Kolon Industries)

(d) Modified polyethylene maleic anhydride copolymer (Fusabond 416D, Dupont)

(e) Dodecanedioic acid dihydrazide (Finechem)

division Impact strength
(kgf · cm / cm) The tensile strength
(kgf / cm2) Formaldehyde
Content (ppm) Example 1 8.5 538 0.6 Example 2 11.4 420 0.4 Example 3 10.9 425 0.7 Example 4 16.4 340 0.3 Example 5 7.8 532 0.5 Comparative Example 1 8.7 426 0.2 Comparative Example 2 8.3 417 0.6 Comparative Example 3 9.4 436 0.8 Comparative Example 5 6.4 545 0.8 Comparative Example 6 8.6 441 6.7 Comparative Example 7 8.3 412 7.9 Comparative Example 8 10.7 426 6.3

As shown in Table 2, the molded articles prepared from the polyoxymethylene resin compositions according to the Examples had excellent mechanical properties such as impact strength and tensile strength, and the formaldehyde gas emission amount by the VDA275 method was also found to be 2 ppm or less.

On the other hand, it can be seen that the comparative example does not satisfy both excellent mechanical properties and formaldehyde gas emission characteristics at the same time.

Therefore, it can be understood that the polyoxymethylene resin composition according to the embodiment of the present invention can be applied as an engineering resin in fields such as electric and electronic devices and the like which require excellent mechanical properties and environmental regulation.

Claims (6)

Based on 100 parts by weight of the polyacetal resin,
1 to 3 parts by weight of a polyether-ester block copolymer;
5 to 50 parts by weight of an ester-based thermoplastic polyurethane elastomer;
0.1 to 5 parts by weight of a modified polyethylene maleic anhydride copolymer; And
And 0.05 to 2 parts by weight of a carboxylic acid hydrazide compound.
The method according to claim 1,
Wherein the amount of the terminal group of the formic acid ester in the polyacetal resin is 1% by weight or less.
The method according to claim 1,
Wherein the thermoplastic polyurethane elastomer is an ester-based thermoplastic polyurethane elastomer having a Shore hardness of 55 to 90A.
The method according to claim 1,
Wherein the content of maleic anhydride in the modified polyethylene maleic anhydride copolymer is 0.5 to 3 parts by weight.
The method according to claim 1,
Wherein the amount of formaldehyde generated is 2 ppm or less as measured by the VDA 275 method.
A molded article comprising the polyoxymethylene resin composition according to any one of claims 1 to 5.