KR20210038107A - 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. Specifically, a purpose of the present invention is to provide: a polyoxymethylene resin composition which has better mechanical properties and heat distortion temperature characteristics than an existing polyoxymethylene resin and has improved thermal stability, thereby reducing a generation rate of formaldehyde during processing; and a molded article manufactured from the same.

Description

Polyoxymethylene resins composition and molding procuced from the same

The present invention relates to a polyoxymethylene resin composition and a molded article produced therefrom.

Polyoxymethylene (POM) resin has excellent mechanical properties, stiffness, creep resistance, chemical resistance, friction/abrasion resistance, long-term durability, and is a crystalline engineering plastic with high crystallinity. Utilizing these features, polyoxymethylene resins are used in a wide range of fields, such as electronic device parts, automobile parts, and industrial parts, and are widely applied to gears or parts around gears requiring wear resistance.

As industrial technology develops, the properties required for materials are diversified and advanced, and especially, in the case of parts used at higher than room temperature or under high loads, dimensional stability and thermal stability are also required in addition to excellent abrasion resistance.

As a conventional technology to satisfy such demands, a method of improving the properties of polyoxymethylene resin by mixing wollastonite, fatty acid, and polyolefin (US Patent No. 6391956), olastonite and melamine-based sub-materials, etc. There is a method of improving the properties of the polyoxymethylene resin by blending (US Patent No. 4987176).

However, in the case of the compositions disclosed through the patent document, the market requirements for polyoxymethylene resins are not satisfied, and excessive use of components is required to improve physical properties.

Accordingly, in order to solve the above problems, the present invention is a polyoxymethylene resin composition that has superior abrasion resistance and improves dimensional stability and thermal stability than the conventional polyoxymethylene resin, thereby reducing the amount of formaldehyde generated during processing, and a polyoxymethylene resin composition prepared therefrom. We want to provide molded products.

A first preferred embodiment of the present invention for solving the above problems is a polyoxymethylene resin; Hindered phenolic antioxidants; Fatty acid metal salts; Inorganic filler; An isocyanate crosslinking agent; And a metal salt pestate-based compound represented by the following Chemical Formula 1 or Chemical Formula 2, wherein the inorganic filler has a Mean aspect ratio (L/D) of 3/1 to 10/1 and an average particle diameter of 5 to 25 μm. It is a stonite polyoxymethylene resin composition.

[Formula 1]

[Formula 2]

In Formulas 1 and 2, M is at least one divalent cation metal selected from Mg, Ca, Ba, Zn and Fe, and R ₁ is an alkyl group having 12 to 32 carbon atoms.

The polyoxymethylene is characterized in that the melting point is 160 to 180 ℃.

The fatty acid metal salt is characterized in that it is a saturated fatty acid having 12 to 32 carbon atoms including at least one alkaline earth metal salt selected from Mg, Ca, and Zn.

Another preferred embodiment of the present invention is to provide a molded article made from the above-described polyoxymethylene resin composition.

The molded article is characterized in that the amount of formaldehyde gas generated is 5 to 15 mg/kg at 190°C and 25 to 40 mg/kg at 220°C.

The polyoxymethylene resin composition according to the present invention has excellent abrasion resistance, dimensional stability, and thermal stability, and can reduce the amount of thermal decomposition and formaldehyde emission that may occur during the molding process, and the molded article manufactured therefrom is an automobile interior or exterior material or It can be applied in various fields such as battery/electronic products.

A first preferred embodiment of the present invention for solving the above problems is a polyoxymethylene resin; Hindered phenolic antioxidants; Fatty acid metal salts; Inorganic filler; An isocyanate crosslinking agent; And a metal salt pestate-based compound represented by Chemical Formula 1 or Chemical Formula 2, wherein the inorganic filler has a Mean aspect ratio (L/D) of 3/1 to 10/1 and an average particle diameter of 5 to 25 μm. It is to provide a knight polyoxymethylene resin composition.

Hereinafter, each component of the resin composition of the present invention will be described in more detail.

Polyoxymethylene

The polyoxymethylene of the present invention includes an oxymethylene -(OCH ₂ ) _n -group as a repeating unit, and either ends are oxymethylene homopolymers blocked by an ester or ether group, Ethylene (-(OCH ₂ CH ₂ ) _n -), oxypropylene (-(OCH ₂ CH ₂ CH ₂ ) _n -), oxybutylene (-(OCH ₂ CH ₂ CH ₂ CH ₂ ) _n -) It may be an oxymethylene-based copolymer, or a terpolymer, in which 2 to 10 oxyalkylene units are inserted randomly, and both ends of the polymer are blocked by an ester or ether group. The structure of the polyoxymethylene copolymer may have not only a linear structure but also a branched and crosslinked structure.

In the present invention, polyoxymethylene serves as a base resin, secures basic mechanical and chemical properties of the resin, and particularly performs an important function in abrasion resistance performance. In this case, the polyoxymethylene may preferably have a melting point of 160 to 180°C.

Although the present invention is not particularly limited thereto, the oxymethylene homopolymer and the oxymethylene-based copolymer may be prepared in the following manner. First, the oxymethylene homopolymer is polymerized by introducing formaldehyde anhydride in an organic solvent containing a basic polymerization catalyst such as, for example, an organic amine, an organic or inorganic tin compound, and a metal hydroxide, and the polymer is filtered, and then acetic acid. It can be prepared by heating in acetic anhydride in the presence of sodium to acetylate the terminal.

In addition, the oxymethylene-based copolymer is, for example, a cyclic oligomer of formaldehyde such as trioxane anhydride or tetraoxane, and ethylene oxide, propylene oxide, 1,3-dioxolane, 1,3-flopandiophor Horse, 1,4-butanediol formal, 1,5-pentanediol formal, 1,6-hexanediol formal, diethylene glycol formal, 1,3-dioxephan, 1,3,5-trioxepan , A cyclic ether such as 1,3,6-trioxocane, etc., is dissolved or suspended in an organic solvent such as cyclohexane or benzene, and then a Lewis acid catalyst such as boron trifluoride diethyl ether is added to polymerize and unstable end It can be prepared by decomposing and removing.

Among these, the polyoxymethylene of the present invention is a cyclic oligomer of trioxane or tetraoxane, more preferably a cyclic oligomer of trioxane and 1,3-dioxolane (1 ,3-Dioxolane) It may be preferable to select an oxymethylene-based copolymer obtained by cationic random copolymerization of a mixture of comonomers. In this case, the oxymethylene-based copolymer includes 0.1 to 10 mol% of oxyethylene repeating units and 90 to 99.9 mol% of oxymethylene repeating units based on the total mol of the polymer from the viewpoint of improving the thermal stability of the polymer and improving the crystallinity of moldability. I can.

Hindered phenolic antioxidant

The hindered phenolic antioxidant of the present invention is, for example, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)-propionate, triethylene glycol- Bis-[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)-propionate], 2,2'-methylenebis-(4-methyl-t-butylphenol), tetrakis[ Methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl propionate]methane, N,N'-bis-3-3(3',5'-di-t- Butyl-4'-hydroxyphenyl) propionylhexamethylenediamine, N,N'-tetramethylene-bis-3-(3'-methyl-5'-t-butyl-4'-hydroxyphenol) propionyl Diamine,N,N'-bis-[3-(3,5-di-t-butyl-4-hydroxyphenol)propionyl]hydrazine, N-saritroyl-N'-satiridenehydrazine, 3 -(N-saritiroyl)amino-1,2,4-triazole and N, N'-bis[2-{3-(3,5-di-t-butyl-4-hydroxyphenyl)propi Onyloxy}ethyl]oxyamide, etc. Particularly preferred antioxidants are triethylene glycol-bis-[3-(3-t-butyl-5-methyl 4-hydroxyphenyl)-propionate] and tetra It may be one or more selected from the kiss [methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane.

The hindered phenolic antioxidant is preferably contained in an amount of 0.01 to 1 part by weight based on 100 parts by weight of polyoxymethylene. When the content of the hindered phenolic antioxidant is less than 0.01 part by weight, it is difficult to perform the role as an antioxidant, and when it exceeds 1 part by weight, mechanical properties may be deteriorated.

Fatty acid metal salt

The fatty acid metal salt of the present invention is a saturated fatty acid having 12 to 32 carbon atoms including at least one alkaline earth metal salt selected from Mg, Ca, and Zn, and is one selected from polyethylene, polypropylene, polybutylene homopolymer, and copolymers thereof. It is a component that improves slide properties by using the above olefin-based polymer and a graft copolymer of at least one vinyl-based polymer selected from polystyrene, acronitrile-styrene copolymer, polyacrylonitrile, and butyl polyacrylate.

The fatty acid metal salt increases compatibility between the polyoxymethylene resin and the graft copolymer, and is used together with the graft polymer to maximize slide characteristics than when the fatty acid metal salt is used alone.

The content of the fatty acid metal salt is preferably 0.1 to 0.5 parts by weight based on 100 parts by weight of polyoxymethylene, and if it is less than 0.1 parts by weight, the function as a lubricant is not sufficient, and if it exceeds 0.5 parts by weight, formaldehyde (FA) It can act as a factor causing occurrence and discoloration of molded products.

Inorganic filler

The inorganic filler of the present invention serves to improve the mechanical properties and heat deflection temperature of the polyoxymethylene resin composition.

The inorganic filler may be at least one selected from the group consisting of talc, cray, glass beads, olastonite, and combinations thereof, preferably olastonite.

The olastonite may have a mean aspect ratio (L/D) of 3/1 to 10/1 and an average particle diameter of 5 to 25 μm.

At this time, the mean aspect ratio (L/D) means the ratio of the length and thickness of olastonite, and the average particle diameter means the particle diameter corresponding to 50% of the weight percentage in the particle size distribution curve of olastonite.

If the mean aspect ratio of the olastonite is less than 3/1, it may be difficult to meet the target physical property level, and if it exceeds 10/1, problems may occur in flowability and dimensional stability of the applied product.

If the average particle diameter of the olastonite is less than 5 μm, it may be difficult to meet the desired target properties in the polyoxymethylene resin due to its short length. If it exceeds 25 μm, problems such as flowability and product surface defects may occur. have.

In addition, the olastonite may be a surface-modified olastonite or a surface-unmodified olastonite, but when mixed with an isocyanate-based crosslinking agent to improve the bonding strength with the polyoxymethylene resin, the surface is unmodified. It is preferably olastonite.

When the olastonite is a surface-modified olastonite, the surface may be modified by a silane-based, fatty acid-based, or the like.

The inorganic filler may contain 1 to 40 parts by weight based on 100 parts by weight of the polyoxymethylene resin, preferably 5 to 25 parts by weight. If the content is less than 1 part by weight, mechanical properties such as flexural strength and thermal deformation temperature are not sufficiently improved, and if it exceeds 40 parts by weight, the polyoxymethylene resin may be decomposed, resulting in poor processability of the polyoxymethylene resin composition. It may cause problems such as high, wear resistance, and surface defects.

Isocyanate crosslinking agent

The crosslinking agent of the present invention is a component for increasing the bonding strength between the polyoxymethylene resin and the inorganic filler.

The crosslinking agent may be an isocyanate compound, preferably an alicyclic isocyanate.

The alicyclic isocyanate is isophorone diisocyanate (IPDI), 1,4-cyclohexylmethane diisocyanate (1,4-cyclohexylmethane diisocyanate; CHDI), 4,4'-dicyclohexylmethane diisocyanate (4, 4'-dicyclohexylmethane diisocyanate; H ₁₂ MDI).

The crosslinking agent has excellent reactivity with polyoxymethylene and silicon dioxide constituting the olastonite by an isocyanate group, so that olastonite and polyoxymethylene can be crosslinked, thereby improving physical properties.

In addition, the crosslinking agent has stability against UV and the like compared to other isocyanate systems due to the alicyclic structure, and thus, the possibility of discoloration may be lowered when used in this configuration.

The crosslinking agent may contain 0.1 to 10 parts by weight based on 100 parts by weight of the polyoxymethylene resin, preferably 0.5 to 7 parts by weight. If the crosslinking agent is less than 0.1 parts by weight, it is not possible to obtain the desired improvement of mechanical properties due to insufficient functional groups to act as a crosslinking agent, and if it exceeds 10 parts by weight, processability problems due to excessive addition of the crosslinking agent and discoloration due to side reactions There is a problem that may cause issues, etc.

Metal salt phosphate compound

The metal salt phosphate-based compound of the present invention serves to modify the unstable terminal group in the polyoxymethylene resin to prevent decomposition by heat during molding processing, and is represented by the following formula (1) or the following formula (2), and one selected or It may be a mixture of two or more.

[Formula 1]

[Formula 2]

In Formulas 1 and 2, M is at least one divalent cation metal selected from Mg, Ca, Ba, Zn and Fe, and R ₁ is an alkyl group having 12 to 32 carbon atoms.

The amount of the metal salt phosphate compound is preferably 0.01 to 2 parts by weight based on 100 parts by weight of polyoxymethylene. When the content of the metal salt phosphate-based compound is less than 0.01 parts by weight, it cannot sufficiently perform the role as a heat-resistant agent, so that the thermal stability of the resin is lowered, and when it exceeds 2 parts by weight, the effect of reducing formaldehyde (FA) is slowed. Or rather, it may cause side effects that increase.

As another preferred embodiment of the present invention, it is to provide a molded article made from the above-described polyoxymethylene resin composition.

In the molded article according to the present invention, the amount of formaldehyde (FA) gas generated according to the VDA275 method is 30 mg/kg or less at 190°C, preferably 5 to 15 mg/kg, and 60 mg/kg or less at 220°C, preferably It can provide a molded article of 25 to 40mg / kg.

The molded article has excellent wear resistance, dimensional stability, and thermal stability, and is suitable for various applications in automobile interior and exterior materials such as gears or electric/electronic products.

[Example]

Hereinafter, the present invention will be described in more detail through examples. These examples are only for describing the present invention in more detail, and the present invention is not limited thereto.

Examples 1 and 2

After drying polyoxymethylene resin (Kolon Plastic, K300EX) at 80°C for 4 hours, inorganic filler, crosslinking agent, metal salt phosphate compound (SAKAI CHEMICAL INDUSTRY CO.LTD, LBT-1830), fatty acid metal salt (Shinwon Chemical Co., Ltd., HI-FLOW) and a hindered phenolic antioxidant (Songwon Industries, SONGNOX 1010) were added and mixed in the ingredients and contents shown in Table 1. The mixed mixture was introduced into the primary inlet of a twin screw extruder and melt-kneaded at 190°C to prepare a polyoxymethylene resin composition. At this time, the content units shown in Table 1 are parts by weight based on 100 parts by weight of the polyoxymethylene resin.

Comparative Examples 1 to 8

A polyoxymethylene resin composition was prepared in the same manner as in Example 1, except that each component and content were changed as described in Table 1.

(end) Inorganic filler Crosslinking agent (character) (car) (Car) (I) (All) (la) (hemp) (bar) (four) (Ah) Example 1 100 11.5 - - - 2.3 - - 0.3 0.3 0.1 Example 2 100 11.9 - - - 5.9 - - 0.3 0.3 0.1 Comparative Example 1 100 - - - - - - - - - - Comparative Example 2 100 11.2 - - - - - - 0.3 0.3 0.1 Comparative Example 3 100 - 11.5 - - 2.3 - - 0.3 0.3 0.1 Comparative Example 4 100 - - 11.5 - 2.3 - - 0.3 0.3 0.1 Comparative Example 5 100 11.5 - - 2.3 - - - 0.3 0.3 0.1 Comparative Example 6 100 11.5 - - - - 2.3 - 0.3 0.3 0.1 Comparative Example 7 100 11.5 - - - - - 2.3 0.3 0.3 0.1 Comparative Example 8 100 11.4 - - - 2.3 - - 0.3 0.3 0.1

-(A): Polyoxymethylene resin (K300EX, Kolon Plastics)

-(B): Wollastonite (Tremin595-025, HPF; average particle diameter: 15㎛, L/D: 5/1, surface unmodified)

-(C): Wollastonite (Tremin939-300AST, HPF; average particle diameter: 30㎛, L/D: 6/1, surface modified with aminosilane)

-(D): Wollastonite (WFC-15, DAE YEON MATERIAL CO.,LTD; average particle diameter: 11㎛, L/D: 18/1, surface modified with stearic acid)

-(E): Crosslinking agent (MC25; HANGZHOU JLS FLAME RETARDANTS CHEMICAL CO., LTD; Melamine type)

-(Bar): crosslinking agent (IPDI; EVONIK INDUSTRIES; Isocyanate type)

-(Company): Crosslinking agent (IPMS; EVONIK INDUSTRIES; Silane system)

-(H): Crosslinking agent (PKHH; GABRIEL; Phenoxy type)

-(I): A metal salt phosphate compound in which the compounds represented by Formulas 1 and 2 are mixed (SAKAI CHEMICAL INDUSTRY CO. LTD, LBT-1830; in Formulas 1 and 2, M is Zn, and R1 is an alkyl group having 18 carbon atoms)

-(Tea): Fatty acid metal salt (HI-FLOW, Shinwon Chemical Co., Ltd.)

-(K): Hindered phenolic antioxidant (Songwon Industries SONGNOX 1010)

Property evaluation

The polyoxymethylene resin compositions prepared in Examples and Comparative Examples were prepared as specimens meeting each measurement standard to measure physical properties, and the results are shown in Table 2.

1. Flexural strength and flexural modulus: The flexural strength and flexural modulus were measured according to ISO 178 standards.

2. Heat deflection temperature: The shrinkage rate was measured in accordance with the ISO 75 standard (1.8 MPa).

3. Formaldehyde gas generation amount: For the prepared polyoxymethylene resin composition, the cylinder temperature was set at 190°C and 220°C when the specimen was injected, and the amount of formaldehyde gas (FA gas) was measured according to the VDA275 method.

division Flexural strength
(MPa) Flexural modulus
(MPa) Heat deflection temperature
(℃) FA GAS 190℃
(mg/kg) FA GAS 220℃
(mg/kg) Example 1 97 3800 115 12 30 Example 2 104 4150 120 13 35 Comparative Example 1 84 2550 95 8 40 Comparative Example 2 90 2800 98 14 33 Comparative Example 3 93 3600 111 13 34 Comparative Example 4 90 3350 103 18 47 Comparative Example 5 88 3350 103 11 27 Comparative Example 6 92 3500 108 12 37 Comparative Example 7 90 3300 102 15 44 Comparative Example 8 95 3700 113 28 70

As can be seen from the results of Table 2, in the case of Examples 1 and 2 compared to Comparative Example 1, which is a polyoxymethylene resin alone, the increase in the amount of FA GAS emission did not appear significantly, whereas the flexural strength, flexural modulus, and heat deflection temperature were remarkably. It was found to be improved and the amount of FA GAS generated at 220°C was reduced.

In addition, compared to Example 1, Comparative Example 2 in which the crosslinking agent of the present invention was not used had poor flexural strength, flexural modulus, and thermal deformation temperature, and was found to increase the amount of formaldehyde emission.

In Comparative Examples 3 and 4 using an inorganic filler different from the inorganic filler of the present invention compared to Example 1, the flexural strength, flexural modulus, and thermal deformation temperature were poor, and the FA GAS emission was increased.

Compared to Example 1, Comparative Examples 5 to 7 that did not include the crosslinking agent of the present invention exhibited a pattern in which the degree of improvement in flexural strength, flexural modulus, and heat deflection temperature decreased, and formaldehyde emission decreased.

Comparative Example 8 did not contain the metal salt phosphate of the present invention, compared to Example 1, it was found that the mechanical properties and formaldehyde emission amount was low.

Claims (6)

Polyoxymethylene resin;
Hindered phenolic antioxidants;
Fatty acid metal salts;
Inorganic filler;
An isocyanate crosslinking agent; And
Including a metal salt pestate-based compound represented by the following formula (1) or the following formula (2),
The inorganic filler has a mean aspect ratio (L/D) of 3/1 to 10/1, and an average particle diameter of 5 to 25 μm of olastonite, a polyoxymethylene resin composition.
[Formula 1]

[Formula 2]

In Formulas 1 and 2, M is at least one divalent cation metal selected from Mg, Ca, Ba, Zn and Fe, and R ₁ is an alkyl group having 12 to 32 carbon atoms. The method of claim 1, wherein based on 100 parts by weight of the polyoxymethylene resin, 0.01 to 1 parts by weight of the hindered phenolic antioxidant, 0.1 to 0.5 parts by weight of the fatty acid metal salt, 1 to 40 parts by weight of the inorganic filler, and the isocyanate A polyoxymethylene resin composition comprising 0.1 to 10 parts by weight of a crosslinking agent and 0.01 to 2 parts by weight of the metal salt pestate compound. The polyoxymethylene resin composition according to claim 1, wherein the polyoxymethylene has a melting point of 160 to 180°C. The polyoxymethylene resin composition according to claim 1, wherein the fatty acid metal salt is a saturated fatty acid having 12 to 32 carbon atoms including at least one alkaline earth metal salt selected from Mg, Ca, and Zn. A molded article manufactured from the polyoxymethylene resin composition of any one of claims 1 to 4. [6] The molded article according to claim 5, wherein the amount of formaldehyde gas generated in the molded article is 5 to 15 mg/kg at 190°C and 25 to 40 mg/kg at 220°C.