KR20190036757A - Polyoxymethylene Resins Composition and Molding procuced from the same - Google Patents

Abstract

The present invention relates to a polyoxymethylene resin composition and a molded article manufactured from the same. More specifically, a purpose of the present invention is to provide the polyoxymethylene resin composition and the molded article manufactured from the same, wherein the polyoxymethylene resin composition has excellent elongation at break, impact resistance characteristics at a room temperature, and impact resistance characteristics at a low temperature, and these characteristics are well-balanced. In addition, the polyoxymethylene resin has excellent flowability during injection-molding, thereby being advantageous in a molding process.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyoxymethylene resin composition and a molded article produced therefrom,

The present invention relates to a polyoxymethylene resin composition and a molded article produced therefrom. More particularly, to a polyoxymethylene resin composition having excellent breaking elongation, normal temperature impact resistance, low temperature impact resistance and high flowability and being advantageous for molding, and a molded article produced therefrom.

Polyoxymethylene resin is an engineering plastic which is used in various fields such as electric and electronic parts and automobile because it has excellent mechanical properties, rigidity, chemical resistance and long-term durability. When the polyoxymethylene resin is used for producing parts such as clips or fasteners, excellent elongation at break and impact resistance at room temperature / low temperature are required. However, since the resin has a high degree of crystallinity and is very hard, when a molded article made of the resin is impacted and cracked, its propagation speed is very fast and it is very easy to break. Research on adding various impact modifiers as a method for improving the impact resistance has been carried out from the past and is actively being carried out at present.

As a method for improving the impact resistance property of polyoxymethylene, a method of adding a thermoplastic polyurethane having a glass transition temperature of -15 캜 or lower (see U.S. Patent Publication No. 1989-4804716), a method of improving fracture elongation and impact resistance (US Patent Publication No. 1990-4929712, U.S. Patent Publication No. 2007-0276064), a method of improving the elongation at break and the impact resistance at room temperature and improving the extrusion processability of the resin and the thermoplastic polyurethane (US Patent Publication No. 2003-6512047, Korean Patent Publication Nos. 2010-0140791 and 2003-0042167), a method of improving the elongation at break and the impact resistance at room temperature, and a method of adding a compound containing modified maleic anhydride group To improve low-temperature impact resistance properties, methyl methacrylate-butadiene-styrene and isocyanate compounds are added together. (Korean Patent Publication No. 2017-0051697) has been proposed.

However, since the isocyanate compound is added to improve the elongation at break, the flowability of the resin is greatly reduced and the molding process becomes difficult. In addition, the development of techniques related to the improvement of the impact resistance at room temperature has been mainly performed. It is necessary to develop a resin composition having good flow properties while securing both excellent tensile elongation, normal temperature impact resistance and low temperature impact resistance.

The present invention provides a polyoxymethylene resin composition which is excellent in the elongation at break, the impact resistance at room temperature and the low temperature, the impact resistance at low temperature, and the flowability, and which is advantageous in molding processing, and a molded article produced therefrom.

(B) 10 to 16 parts by weight of a thermoplastic polyurethane, (c) an ethylene-acrylate copolymer (2), and (3) (E) 0.01 to 0.1 part by weight of a hindered phenol-based antioxidant, (f) 0.01 to 0.1 part by weight of a release agent, and (d) 2 to 5 parts by weight of a polyether- To provide a composition.

The ethylene acrylate copolymer (c) is a compound represented by the following formula (1).

≪ Formula 1 >

(Wherein R ₁ is an alkyl group having 1 to 3 carbon atoms, x is an integer of 60 to 130, and y is an integer of 10 to 20.)

The ethylene acrylate copolymer (c) has a weight ratio (c1: c2) of the ethylene polymer (c1) and the (c2) acrylate polymer, which are the main chains in the ethylene acrylate copolymer, of from 85:15 to 70:30 .

The polyether-ester block copolymer (d) has a mass ratio (d1: d2) of the soft segment (d1) to the hard segment (d1) of the polyether- .

The polyether-ester block copolymer (d) has a shore hardness of 28-55D.

Another embodiment of the present invention is to provide a molded article produced from the polyoxymethylene resin composition.

The Izod Notched low temperature impact strength (-30 ° C) was 9 kgfcm / cm, the tensile elongation was 180% or more, the melt index (MI) was 8.0 g / 10 min or more.

The polyoxymethylene resin composition according to the present invention is excellent in flowability and is advantageous in molding processing. Further, the molded article produced from the polyoxymethylene resin composition according to the present invention is excellent in elongation at break, impact resistance at room temperature, and impact resistance at low temperatures.

(A) 10 to 16 parts by weight of a thermoplastic polyurethane (b) based on 100 parts by weight of a polyoxymethylene resin and (a) a polyoxymethylene resin, (c) an ethylene acrylate copolymer (D) 2 to 5 parts by weight of a polyether-ester block copolymer, (e) 0.01 to 0.1 parts by weight of a hindered phenol antioxidant, and (f) 0.01 to 0.1 parts by weight of a release agent. And to provide a methylene resin composition.

Accordingly, in order to solve the problems of the present invention, when a thermoplastic polyurethane, an ethylene acrylate copolymer and a polyether-ester block copolymer are blended together in a polyoxymethylene resin, the impact resistance at room temperature and the low temperature shock resistance property are improved, and an isocyanate- It is possible to obtain an excellent elongation without fracture. Further, it has been found that the flowability of the resin is not reduced as the isocyanate-based coupling agent is not formulated.

Hereinafter, the present invention will be described in detail.

[(a) Polyoxymethylene  Suzy]

Is characterized in that it has a main unit of oxymethylene and 0.5 to 5 parts by weight of an oxyalkylene unit having 2 to 8 adjacent carbon atoms in the main unit.

The polyoxymethylene resin used in the present invention generally comprises homopolymers, copolymers or terpolymers in which the main unit is an oxymethylene group (- (- OCH ₂ ) _n -). Of these, copolymers are used in the present invention.

The polyoxymethylene resin can be obtained by cationic random copolymerization of a cyclic oligomer of trioxane or tetraoxane, preferably a cyclic oligomer of trioxane, and a comonomer. The comonomers include oxyethylene (- (OCH ₂ CH ₂ ) _n -), oxypropylene (- (OCH ₂ CH ₂ CH ₂ ) _n -), oxybutylene (- (OCH ₂ CH ₂ CH ₂ CH ₂ ) _n -) and branched oxyalkylene groups having 2 to 10 carbon atoms and branched oxyalkylene groups. Examples thereof include 1,3-dioxolane, 1,3-dioxepane, and 1,3,5-trioxepane.

In particular, the polyoxymethylene resin used in the present invention can be obtained by adding a 1,3-dioxolane comonomer to the main monomer, trioxane, followed by cationic random copolymerization using a Lewis acid catalyst. The structure of the polyoxymethylene resin may have not only a linear structure but also a crosslinked or branched structure.

[(b) Thermoplastic polyurethane]

The thermoplastic polyurethane (b) used in the present invention is a thermoplastic polyurethane used in the present invention, wherein (b1) a polyol containing an ester bond constituting a soft segment, (b2) a diisocyanate constituting a hard segment, and (b3) . The soft segment and the hard segment together are dispersed in polyoxymethylene to act as a main shockproofing agent which absorbs and mitigates the impact when an impact is applied from the outside.

The polyol (b1) constituting the soft segment is a polyester-diol such as polyethylene-adipate, polybutylene-adipate and polyether-diol such as polypropylene-glycol and polytetramethylene- Can be used. As the diisocyanate (b2) constituting the hard segment, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and the like can be used. The low-molecular diol (b3) which is a chain extender may be ethylene-glycol, tetramethylene-glycol and the like. Further, the thermoplastic polyurethane of the present invention is produced by using a conventional method.

The blending amount of the thermoplastic polyurethane is 10 to 16 parts by weight, preferably 12 to 15 parts by weight per 100 parts by weight of the polyoxymethylene resin. When the amount is less than 10 parts by weight, it is difficult to obtain excellent elongation at break and impact resistance. When the amount is more than 16 parts by weight, mechanical strength is deteriorated.

[(c) Ethylene Acrylate  Copolymer]

In the present invention, (c) an ethylene acrylate copolymer is included as an auxiliary shockproofing agent (1). Particularly, the ethylene acrylate copolymer is a compound represented by the following general formula (1), and it is preferable to have an alkyl group having 1 to 3 carbon atoms bonded to acrylate.

≪ Formula 1 >

(Wherein R ₁ is an alkyl group having 1 to 3 carbon atoms, x is an integer of 60 to 130, and y is an integer of 10 to 20.)

When R ₁ of the acrylate group has 1 to 3 carbon atoms in the formula (1), the polyoxymethylene matrix is uniformly dispersed in the matrix together with the thermoplastic polyurethane to increase the impact resistance. In addition, when R ₁ is not contained in the formula (1), there is no part capable of absorbing shock even when dispersed in a polyoxymethylene matrix, and therefore there is a problem in that the impact resistance property sharply decreases.

The (c) ethylene acrylate copolymer may have a weight ratio (c1: c2) of 85: 15 to 70: 30 of the main chain (c1) ethylene polymer and the (c2) acrylate polymer.

When the mass ratio of the (c1) ethylene polymer to the (c2) acrylate polymer is within the above range, the glass transition temperature is -15 ° C or less and the effect of modifying the room temperature impact property and the low temperature impact property at the time of prescription can be obtained.

The ethylene acrylate copolymer (c) is preferably included in an amount of 2 to 5 parts by weight based on 100 parts by weight of the polyoxymethylene resin. If the content is less than 2 parts by weight, the effect as an auxiliary shockproofing agent is insignificant. If the content is more than 5 parts by weight, it may cause a decrease in elongation at break and generation of die swell during extrusion processing.

[(d) Polyether-ester block copolymer]

In the present invention, (d) a polyether-ester block copolymer is added as an auxiliary shockproofing agent (2), and the copolymer is produced by polymerization reaction of dimethyl terephthalate with 1,4-butanediol and polytetramethylene oxide glycol Is a random block copolymer produced. The polyether-ester block copolymer has both (d1) soft segment and (d2) hard segment. (D1) is produced by the reaction of dimethyl terephthalate and polytetramethylene oxide, and (d2) is formed by the reaction of dimethyl terephthalate and 1,4-butanediol. The polyether-ester block copolymer (d1) has a soft segment length (d2) which is much longer than a hard segment, giving flexibility and recovery properties.

Particularly in the present invention, the polyether-ester block copolymer can be used in which the mass ratio (d1: d2) of soft segment (d1) and hard segment (d2) is from 68:32 to 40:60 and shore hardness is 28-55D have.

When the mass ratio of the soft segment (d1) and the hard segment (d2) is within the above range, the glass transition temperature is as low as -30 ° C or less and is supposed to have a superior effect in modifying the impact resistance characteristics, especially the low temperature impact resistance characteristics, Can be obtained.

In addition, when the shore hardness is within the above range, the tensile elongation is very high, so that it is dispersed in polyoxymethylene and the effect of enhancing the tensile elongation of the composition is obtained. The polyether-ester block copolymer is preferably contained in an amount of 2 to 5 parts by weight based on 100 parts by weight of the polyoxymethylene resin. If the content is less than 2 parts by weight, the effect as an auxiliary shockproofing agent is insignificant. If the content is more than 5 parts by weight, it may cause a decrease in elongation at break and generation of die swell during extrusion processing.

[(e) Hinder  Phenol antioxidant]

In the present invention, the hindered phenol-based antioxidant acts to prevent radicals generated by breakage of bonds when heat is applied to the resin and to prevent continuous destruction of the bonds of the polymer. The material that can be used as the hindered phenol antioxidant is n-octadecyl-3- (3,5'-di-tert-butyl-4-hydroxyphenyl) -propionate, triethylene glycol- Methylene bis- (4-methyl-tertiary-butylphenol), tetrakis (triphenylphosphine) Methane, N, N'-bis-3- (3,5'-di-tert-butylphenyl) (3-methyl-5-tertiary-butyl-4-hydroxyphenol) propionyldiamine, N, N'-tetramethylene- (N, N'-bis [3- (3,5'-ditertiary-butyl-4-hydroxyphenol) propionyl] hydrazine, N-salitiroyl- Amino-1,2,4-triazole and N, N'-bis [2- {3- (3,5'-ditertiary- Phenyl) propionyloxy} ] Oxy and the like amides. Particularly, antioxidants which can be preferably used in the present invention include tetrakis [methylene-3- (3,5'-ditertiary-butyl-4-hydroxyphenyl) propionate] methane and triethylene glycol- Bis (3-tertiary-butyl-4-hydroxy-5-methylphenyl) propionate. Such an antioxidant may be selectively used in combination with one or more kinds of antioxidants.

The hindered phenol antioxidant may be contained in an amount of 0.01 to 0.1 part by weight based on 100 parts by weight of the polyoxymethylene resin. When the content is less than 0.01 part by weight, the effect is insignificant. When the content is more than 0.1 part by weight, it may act as an impurity.

[(f) Release agent ]

In the present invention, the release agent is added for the purpose of securing the injection property and for the purpose of helping the processability. As the release agent, a material rotor including paraffin wax, oxidized paraffin wax, polyethylene wax, low molecular weight ethylene vinyl acetate, N, N'-ethylene bisstearamide, erucamide, and oleamide may be selected and used. Particularly, the releasing agent which can be preferably used in the present invention is N, N'-ethylenebismostearamide.

The hindered phenol antioxidant may be contained in an amount of 0.01 to 0.1 part by weight based on 100 parts by weight of the polyoxymethylene resin. When the content is less than 0.01 part by weight, the effect is insignificant. When the content is more than 0.1 part by weight, it can act as an impurity.

Additives such as colorants, plasticizers, nucleating agents, and formaldehyde scavenger may be additionally included within the range not to offset the effects of the present invention.

Thus, the present invention can provide a polyoxymethylene resin composition which is excellent in normal temperature / low temperature impact resistance and elongation at break of a molded article, and at the same time, is excellent in flowability and is advantageous in molding processing.

According to another embodiment of the present invention, there is provided a molded article produced from the above-mentioned polyoxymethylene resin composition.

The molded article manufactured using this polyoxymethylene composition has a Izod Notched room temperature impact strength (23 ° C) of 20 kgfcm / cm or more measured by ASTM D256 and Izod Notched low temperature impact strength (-30 ° C) of 9 kgfcm / cm or more And has a tensile elongation of 180% or more as measured by ASTM D638 and a melt index (MI) of 8.0 g / 10 min or more as measured by ASTM D1238. Thus, excellent mechanical characteristics and flowability can be secured at the same time.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for the purpose of illustrating the present invention more specifically, and the present invention is not limited thereto.

Example  1 to 6

(C) component and a polyether-ester block copolymer of component (d), (e) a thermoplastic polyurethane of component (b) as a main shockproofing agent in polyoxymethylene , The hindered phenol-based antioxidant, and the addition amount of the releasing agent of the component (f) in the contents shown in Table 1, to prepare a polyoxymethylene resin composition. Here, the content units in Table 1 are parts by weight based on 100 parts by weight of the polyoxymethylene resin.

Comparative Example  1 to 8

(C) component and a polyether-ester block copolymer of component (d), (e) a thermoplastic polyurethane of component (b) as a main shockproofing agent in polyoxymethylene Hindered phenol-based antioxidant, and (f) the release agent in the ratio shown in Table 1, to prepare a polyoxymethylene resin composition.

A low-density polyethylene grafted maleic anhydride or a high-density polyethylene grafted maleic anhydride was added in place of the ethylene acrylate copolymer as the component (c) to prepare a resin composition.

Property evaluation

The properties of the polyoxymethylene resin compositions prepared in Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 2.

1. Impact Strength at Room Temperature and Impact Strength at Low Temperature: The Izod Notched impact strength was measured at 23 ° C at room temperature and -30 ° C at low temperature in accordance with ASTM D256.

2. Elongation at break: Measured according to ASTM D638 standard.

3. Melt Index (MI): Measured at 190 占 폚 and 2.16 kg according to ASTM D1238 standard.

division end I All la hemp bar four Ah character Car Example 1 100.0 14.0 0.0 0.0 3.0 3.0 0.0 0.0 0.1 0.1 Example 2 100.0 14.0 3.0 0.0 0.0 3.0 0.0 0.0 0.1 0.1 Example 3 100.0 14.0 0.0 3.0 0.0 3.0 0.0 0.0 0.1 0.1 Example 4 100.0 16.0 0.0 0.0 2.0 2.0 0.0 0.0 0.1 0.1 Example 5 100.0 12.0 0.0 0.0 5.0 3.0 0.0 0.0 0.1 0.1 Example 6 100.0 12.0 0.0 0.0 3.0 5.0 0.0 0.0 0.1 0.1 Comparative Example 1 100.0 14.0 0.0 0.0 0.0 3.0 3.0 0.0 0.1 0.1 Comparative Example 2 100.0 14.0 0.0 0.0 0.0 3.0 0.0 3.0 0.1 0.1 Comparative Example 3 100.0 16.0 0.0 0.0 1.0 3.0 0.0 0.0 0.1 0.1 Comparative Example 4 100.0 7.0 0.0 0.0 10.0 3.0 0.0 0.0 0.1 0.1 Comparative Example 5 100.0 16.0 0.0 0.0 1.0 3.0 0.0 0.0 0.1 0.1 Comparative Example 6 100.0 7.0 0.0 0.0 3.0 10.0 0.0 0.0 0.1 0.1 Comparative Example 7 100.0 17.0 0.0 0.0 3.0 0.0 0.0 0.0 0.1 0.1 Comparative Example 8 100.0 17.0 0.0 0.0 0.0 3.0 0.0 0.0 0.1 0.1

: Polyoxymethylene resin (Kolon Plastics, K300)

B: Thermoplastic polyurethane (Songwon, P-3175A)

C: The mass ratio (c1: c2) of the ethylene-methyl acrylate copolymer (Arkema, 29MA03T: (c1) ethylene polymer and (c2) acrylate polymer: 71:29)

The mass ratio (c1: c2) of the ethylene-ethyl acrylate copolymer (UBE, ZE708: (c1) ethylene polymer and (c2) acrylate polymer:

The mass ratio (c1: c2) of the ethylene-butyl acrylate copolymer (Dupont, AC3427: (c1) ethylene polymer and (c2) acrylate polymer: 73:27)

Bar: a mass ratio (d1: d2) of a polyether-ester block copolymer (Kolon Plastics, KP3328; (d1) soft segment and (d2) hard segment: 68:32, shore hardness: 28D)

Yarn: Low density polyethylene graft maleic anhydride (Arkema, OREVAC 18341)

Ah: High density polyethylene grafted maleic anhydride (Arkema, OREVAC 18507)

Hindered phenolic antioxidant (Songwon, SONGNOX 1010)

KA: Hyungje (Shinwon Chemical, HI-LUBE 500P)

division Izod Notched impact strength
(23 < 0 > C, kgfcm / cm) Izod Notched impact strength
(-30 < 0 > C, kgfcm / cm) Fracture
(%) Melt Index
(190 DEG C, 2.16 kg) Example 1 23.2 10.8 240 8.3 Example 2 20.6 9.0 180 8.0 Example 3 21.8 9.8 220 8.0 Example 4 20.2 9.2 220 8.7 Example 5 20.3 11.8 210 8.6 Example 6 20.1 12.0 200 8.4 Comparative Example 1 7.1 3.8 140 7.6 Comparative Example 2 8.5 4.6 170 7.6 Comparative Example 3 16.3 8.0 256 8.5 Comparative Example 4 16.5 9.9 126 8.9 Comparative Example 5 15.8 8.1 220 8.3 Comparative Example 6 15.1 10.2 120 9.5 Comparative Example 7 15.5 7.7 230 8.6 Comparative Example 8 15.6 7.8 280 8.8

As shown in Examples 1 to 6, the addition of an appropriate amount of an ethylene acrylate copolymer and a polyethylene-ester block copolymer results in excellent breaking elongation, room temperature impact resistance, low temperature impact resistance, I can confirm that this is good.

On the other hand, when low-density polyethylene grafted maleic anhydride without an acrylate group was prescribed instead of ethylene acrylate copolymer as in Comparative Example 1, the elongation at break of 42%, the impact strength at room temperature of 70%, and the impact strength at low temperature of 65% , Respectively. Similarly, when high-density polyethylene grafted maleic anhydride without an acrylate group was prescribed instead of an ethylene acrylate polymer as in Comparative Example 2, the elongation at break of 30%, the impact strength at room temperature of 65%, and the impact strength at low temperature of 57% were reduced . From these two results, it can be confirmed that the ethylene acrylate copolymer plays an important role in improving the room temperature impact property and the low temperature impact property.

Also, as in Comparative Example 3, when 1 part by weight of ethylene acrylate polymer was formulated in a small amount, it was confirmed that the elongation at break was increased compared with Example 1, but the impact strength at room temperature was reduced by 29% and the impact strength at low temperature was decreased by 26%. As in Comparative Example 4, when 10 parts by weight of an ethylene acrylate copolymer is formulated in an excessive amount, it is understood that the elongation at break is reduced by 48%, the impact strength at room temperature is reduced by 30%, and the impact strength at low temperature is decreased by 8% The die swell was generated in large quantities and strand formation was difficult. From these two results, it can be seen that excellent elongation at break, room temperature impact resistance and low temperature impact resistance can be obtained simultaneously if an appropriate amount of ethylene acrylate polymer is added.

When 1 part by weight of a polyether-ester block copolymer was added in a small amount as in Comparative Example 5, the elongation at break was increased compared to Example 1, but the impact strength at room temperature was 32% and the impact strength at low temperature was 25%. When the polyether-ester block copolymer was formulated in an amount of 10 parts by weight as in Comparative Example 6, it was found that the elongation at break of 48%, the impact strength at room temperature of 30% and the impact strength at low temperature of 6% The die swell was significantly increased in the naked eye and strand formation was difficult. From these two results, it can be seen that excellent rupture elongation, room temperature impact resistance characteristic, and low temperature impact resistance characteristic can be obtained simultaneously if a proper amount of polyether-ester block copolymer is added.

As in Comparative Example 7, when the ethylene acrylate copolymer alone was prescribed and the polyethylene-ester block copolymer was not prescribed, the elongation at break was similar to that of Example 1, but the impact strength at room temperature was 35% and the impact strength at low temperature was 25% . In addition, as in Comparative Example 8, when the polyethylene-ester block copolymer alone was prescribed and the ethylene acrylate copolymer was not prescribed, the elongation at break was increased compared with Example 1, but the impact strength at room temperature was 35% and the impact strength at low temperature was reduced by 25% Respectively. From these two results, it can be confirmed that excellent combination of an ethylene acrylate copolymer and a polyether-ester block copolymer can achieve excellent room temperature impact resistance and low temperature impact resistance.

Claims (7)

(b) 10 to 16 parts by weight of a thermoplastic polyurethane, (c) 2 to 5 parts by weight of an ethylene acrylate copolymer, (d) a polyoxymethylene resin, and (d) 2 to 5 parts by weight of a polyether-ester block copolymer, (e) 0.01 to 0.1 parts by weight of a hindered phenol antioxidant, and (f) 0.01 to 0.1 parts by weight of a release agent.
2. The polyoxymethylene resin composition according to claim 1, wherein the ethylene acrylate copolymer (c) is a compound represented by the following formula (1)
≪ Formula 1 >

(Wherein R ₁ is an alkyl group having 1 to 3 carbon atoms, x is an integer of 60 to 130, and y is an integer of 10 to 20.)
The curable resin composition according to claim 1, wherein the ethylene acrylate copolymer (c) has a weight ratio (c1: c2) of the ethylene polymer (c1) and the acrylate polymer (c2), which are the main chains in the ethylene acrylate copolymer, 15 to 70: 30.
The polyether-ester block copolymer according to claim 1, wherein the (d) polyether-ester block copolymer has a mass ratio (d1: d2) of soft segment (d1) 32 to 40: 60.
The polyoxymethylene resin composition according to claim 1, wherein the polyether-ester block copolymer (d) has a shore hardness of 28-55 D.
A molded article produced from the polyoxymethylene resin composition according to any one of claims 1 to 5.
The molded article according to claim 6, wherein the molded article has Izod Notched normal temperature impact strength (23 캜) of 20 kgfcm / cm or more, Izod Notched low temperature impact strength (-30 캜) of 9 kgfcm / cm, a tensile elongation of 180% And an Index (MI) of 8.0 g / 10 min or more.