KR20160083646A - Polyoxymethylene Resin Composition and Molding Product Including the Same - Google Patents

Abstract

The present invention relates to a polyoxymethylene resin composition, comprising, with respect to 100 parts by weight of polyoxymethylene, 10-30 parts by weight of calcium carbonate; 0.05-0.5 parts by weight of fatty acid esters; and 0.05-1.0 parts by weight of a coupling agent. In addition, the present invention relates to a molded product manufactured by using the same. The polyoxymethylene resin composition has improved properties of impact strength, elasticity, and toughness.

Description

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

The present invention relates to a polyoxymethylene resin composition and a molded article produced using the same.

BACKGROUND ART Polyoxymethylene resin is known as a crystalline engineering plastic having excellent mechanical properties, rigidity, creep resistance, chemical resistance, friction / abrasion characteristics, long term durability, and high crystallinity. And the like. In recent years, as the use of such polyoxymethyl resin has been widely expanded, a resin composition having improved properties of a resin as a material thereof has been required and produced.

Particularly, such polyoxymethylene has been widely used as a plastic fitting part due to excellent chemical resistance and long-term durability. Generally, a plastic fitting part is a part connected between a pipe and a pipe, and is a field that requires a balance of mechanical characteristics, wear resistance and dimensional stability. Such plastic fitting parts sometimes have a large size or a specific shape of a T shape, which is sometimes applied to products having a large flow amount, and thus may require higher mechanical properties than a general polyoxymethylene resin. Conventionally, glass fiber, carbon fiber, talc, and inorganic filler are filled in polyoxymethylene resin to meet market demand.

However, blending an inorganic filler such as glass fiber, carbon fiber and talc into polyoxymethylene resin is effective for improving mechanical strength and rigidity, but tends to decrease toughness and long-term durability. Therefore, it is an effective method in terms of balance of mechanical properties I could not. Accordingly, as an alternative to the inorganic filler, there has been proposed a resin composition containing polyoxymethylene in which calcium carbonate having excellent dispersibility in polyoxymethylene and having a relatively good balance between toughness and mechanical properties is relatively good. However, calcium carbonate is not sufficiently adhered to a resin, and research on various formulations is still required to improve the mechanical properties and toughness of the material.

Conventional techniques relating to polyoxymethylene resin blended with calcium carbonate include a method of melt-kneading calcium carbonate surface-treated with fatty acid and metal salt (JP-A-2011-162607), calcium carbonate- (Japanese Unexamined Patent Application Publication No. 2006-137783), a method of producing Ca by adding a mixture of organic acid and fatty acid ester to calcium carbonate having a predetermined ratio of Na and Sr, 0113995), a method of preparing an aminosilane-treated calcium carbonate by blending an olefin grafted polymer (JP-A-2013-136656), a method of preparing calcium carbonate by mixing a reactive nitrogen compound (quaternary ammonium compound) (Japanese Laid-Open Patent Publication No. 2013-124364).

However, the balance of mechanical properties has not yet been solved. Particularly, there is a problem in that the impact strength is lowered due to dispersion and interfacial adhesion of calcium carbonate. In recent years, Was not sufficient to satisfy the requirements of the present invention.

Accordingly, it is an object of the present invention to provide a polyoxymethylene resin composition improved in toughness, elastic modulus and impact strength by adding a specific coupling agent to calcium carbonate coated with an organic acid, and a resin molded article using the same.

In a preferred embodiment of the present invention, 10 to 30 parts by weight of calcium carbonate surface-treated with an organic acid, 0.05 to 0.5 parts by weight of a fatty acid ester and 0.05 to 1.0 part by weight of a coupling agent are contained based on 100 parts by weight of polyoxymethylene Is a polyoxymethylene resin composition.

The calcium carbonate according to this embodiment may be heavy calcium carbonate having an average particle diameter of 1.0 to 2.0 mu m.

The organic acid according to this embodiment may be selected from the group consisting of saturated fatty acids including Lauric acid, Capric acid, Myristic acid and Stearic acid; And at least one selected from unsaturated fatty acids including oleic acid, linolic acid and linolenic acid.

The fatty acid ester according to this embodiment may be selected from the group consisting of glycerol monostearate, glycerol monobehenate, ethylene glycol stearate, propylene glycol stearate, sorbitan monostearate, At least one selected from the group consisting of Sorbitan monostearate and Sorbitan monobehenate.

The coupling agent may be at least one selected from the titanate series represented by the following formula (1) and the zirconate series represented by the following formula (2).

(Formula 1)

 (2)

,

,

및

중 선택된 1 종이다.In the above formulas (1) and (2), R ₁ and R ₂ are independently

,

,

And

≪ / RTI >

The polyoxymethylene according to this embodiment may have a weight average molecular weight (Mw) of 150,000 to 300,000 and a melting point of 165 to 172 ° C.

Still another preferred embodiment of the present invention is a molded article formed from the above polyoxymethylene resin composition.

The molded product may have a tensile elongation of 50 to 80% as measured by ASTM D638, an Izod impact strength as measured by ASTM D256 of 5.0 to 8.0 kg.cm/cm, an ASTM D790 measurement standard, a flexural modulus of 34,000 kgf / cm ² or more And ASTM D955 measurement shrinkage may be less than 1.5%.

According to the present invention, it is possible to provide a polyoxymethylene resin composition superior in balance of mechanical properties to conventional polyoxymethylene resins.

In particular, it is possible to provide a polyoxymethylene resin composition having improved toughness and elastic modulus, without deterioration in impact properties, and at the same time, having a low shrinkage ratio after molding, thereby being useful for plastic fitting parts that are subjected to long- Can be used.

According to one aspect of the present invention, there is provided a polyoxymethylene resin composition comprising 10 to 30 parts by weight of calcium carbonate surface-treated with an organic acid based on 100 parts by weight of polyoxymethylene, 0.05 to 0.5 parts by weight of a fatty acid ester and 0.05 to 1.0 part by weight of a coupling agent Composition can be provided.

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

[ Polyoxymethylene ]

The polyoxymethylene used in the present invention means a homopolymer, a copolymer or a ternary copolymer having an oxymethylene {(OCH ₂ ) _n } group as a main unit, preferably a polyoxymethylene copolymer. The polyoxymethylene is not particularly limited as long as it is a commercially available polyoxymethylene, but it has a weight average molecular weight (Mw) as measured by GPC (Gel Permeation Chromatography) of 150000 to 300000 and a melting point of 165 to 172 ° C May be more preferable.

The polyoxymethylene copolymer can be obtained by cationic random copolymerization of a cyclic oligomer of trioxane or tetraoxane, more preferably a mixture of cyclic oligomer of trioxane and a comonomer, and more specifically 1,3-dioxolane comonomer Is added to the main monomer, trioxane, followed by cation random copolymerization using a Lewis acid catalyst, whereby a polyoxymethylene copolymer can be produced in a form having two or more bonding carbon atoms in the main chain.

At this time, the polyoxymethylene copolymer may have a branched structure and a crosslinked (cross-linked) structure as well as a linear structure. (- (OCH ₂ CH ₂ ) _n -), oxypropylene (- (OCH ₂ CH ₂ CH ₂ ) _n -) as a constituent unit of the comonomer other than the oxymethylene group as the main chain, And oxybutylene (- (OCH ₂ CH ₂ CH ₂ CH ₂ ) _n -), among which oxyalkylene groups having 2 to 4 carbon atoms and branched oxyalkylene groups More preferably an oxyethylene group, and most preferably an oxyethylene group.

Although not particularly limited thereto, in the above polyoxymethylene copolymer, the comonomer is at least one selected from the group consisting of ethylene oxide, 1,3-dioxolane, 1,3-dioxepane (1,3 Dioxepane, and 1,3,5-trioxepane. Of these, 1,3-dioxolane is more preferably copolymerized.

[Calcium carbonate]

According to a preferred embodiment of the present invention, the calcium carbonate may be heavy calcium carbonate, which is an organic acid surface-treated heavy calcium carbonate having an average particle diameter of 1.0 to 2.0 μm. In the present invention, calcium carbonate is preferably added in an amount of 10 to 30 parts by weight based on 100 parts by weight of the polyoxymethylene. If the content is less than the above range, the tensile elongation may be poor or the impact strength may be significantly reduced.

Generally, calcium carbonate is divided into heavy calcium carbonate and light calcium carbonate according to the production method. Heavy calcium carbonate is produced by physically pulverizing and classifying high purity crystalline limestone having high whiteness, and is generally used for polyoxymethylene It is characterized by a larger particle size and a wider particle distribution than hard calcium carbonate. On the other hand, hard calcium carbonate is prepared by reacting limestone ore with calcined lime by heat treatment at 900 ° C or higher and reacting it with carbon dioxide, and can be made into various forms of calcium carbonate for various purposes.

The hard calcium carbonate has advantages in that the control of the shape of the hard calcium carbonate is easier than that of the heavy calcium carbonate, and the particle size and the particle size distribution can be easily controlled and diversified according to the use purpose. For this reason, heavy calcium carbonate may cause problems of physical properties due to degradation of dispersibility when used in plastics, but it is less expensive than hard calcium carbonate. Accordingly, in the present invention, by treating the low-priced heavy calcium carbonate with an organic acid, the particle shape, which is a disadvantage of the heavy calcium carbonate, can be uniformly controlled, and at the same time, the particle distribution can be narrowed and the dispersibility can be enhanced.

The surface-treated heavy calcium carbonate of the present invention can be obtained by adding calcium carbonate particles to saturated calcium carbonate particles containing a surfactant such as Lauric acid, Capric acid, Myristic acid and Stearic acid fatty acid; And at least one organic acid selected from oleic acid, linolic acid and linolenic acid. These organic acids may be used alone or in combination of two or more thereof as required.

[Fatty acid ester]

According to a preferred embodiment of the present invention, 0.05 to 0.5 parts by weight of a fatty acid ester is contained relative to 100 parts by weight of the polyoxymethylene in order to improve the processability, releasability and slidability of the polyoxymethylene resin and to suppress the contamination of the organic materials sticking to the mold can do. When the amount of the fatty acid ester is less than 0.05 part by weight, the effect on the workability and releasability is insufficient. When the amount of the fatty acid ester is more than 0.5 part by weight, the property of polyoxymethylene may be deteriorated.

In the present invention, the fatty acid ester is a fatty acid ester obtained by condensation polymerization of a monohydric or polyhydric alcohol and a fatty acid, and is preferably a fatty acid ester such as glycerol monostearate, glycerol monobehenate, ethylene glycol stearate at least one selected from glycol stearate, propylene glycol stearate, sorbitan monostearate and sorbitan monobehenate.

[Coupling agent]

According to a preferred embodiment of the present invention, 0.05 to 1.0 part by weight of a coupling agent may be contained relative to 100 parts by weight of the polyoxymethylene so that the calcium carbonate and the polyoxymethylene can be further improved in physical properties by improving the chemical- have. When the content of the coupling agent is less than 0.05 part by weight, the physical properties of the composition are not greatly improved. When the amount of the coupling agent is more than 1.0 part by weight, the physical properties may be deteriorated.

In the present invention, the coupling agent is preferably at least one selected from the titanate series represented by the following formula (1) and the zirconate series represented by the following formula (2), and these may be used singly or in combination . Titanate series or zirconate series coupling agents increase the workability in the melt-kneading of high content of calcium carbonate with polyoxymethylene in addition to the sliding properties, and they lower the processing temperature by improving the flowability. In addition, since it also improves the mechanical properties through the process rheology by the catalytic mechanism such as in-situ metallocene (US Pat. No. 4,657,988), the effect of improving the mechanical properties of the resin composition of the present invention can be further improved.

 (Formula 1)

 (2)

,

,

및

중 선택된 1 종이다.
In the above formulas (1) and (2), R ₁ and R ₂ are independently

,

,

And

≪ / RTI >

The composition of the present invention may contain an antioxidant such as a colorant, a nucleating agent, a plasticizer, a hindered phenol compound or a phosphate compound, an ethylene bis ester, a polyethylene wax ), A light stabilizer such as a benzophenone compound, a benzotriazole compound, melamine, guanidine, Dicyan diamide and the like, But may also include, but are not necessarily limited to, additives such as formaldehyde builders, lubricants, and the like.

Accordingly, the present invention can provide a polyoxymethylene resin composition suitable for use in a plastic fitting part which is low in shrinkage ratio, excellent in toughness and modulus of elasticity, and particularly excellent in long-term pressure. The molded article produced using the polyoxymethylene resin composition may have a tensile elongation of 50 to 80% as measured by ASTM D638 and an Izod impact strength of 5.0 to 8.0 kg.cm/cm as measured by ASTM D256. ASTM D790 Measurement standard, flexural modulus of 34,000 kgf / cm ² or more And ASTM D955 measurement standard shrinkage ratio of 1.5% or less, the balance of mechanical properties can be excellent.

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.

The components used in the examples of the present invention are as follows.

- polyoxymethylene: KOCETAL ^® K300, Kolon Plastics, Inc., Melt Index (MI) 9 g / 10 min

- Surface treated calcium carbonate: ST5000, Lekkem

- Fatty acid esters: G-MB-glycerin monobehenate, KAO chemical

- coupling agent: LICA 01 - neopentyldiallyloxy-tRNAe decanoyl titanate, Hansol FINE Co., Ltd.

Example  1 to Example  8

Polyoxymethylene, surface-treated calcium carbonate, fatty acid ester and coupling agent were melt-kneaded in the ratios shown in Table 1 to prepare a polyoxymethylene resin composition.

Comparative Example  1 to Example  7

Polyoxymethylene, surface-treated calcium carbonate, fatty acid ester and coupling agent were melt-kneaded in the ratios shown in Table 1 to prepare a polyoxymethylene resin composition.

division
(Parts by weight) Polyoxymethylene Surface treated calcium carbonate Coupling agent Fatty acid ester Example 1 100 25 0.05 0.2 Example 2 100 25 0.1 0.2 Example 3 100 25 0.2 0.2 Example 4 100 25 0.3 0.2 Example 5 100 25 1.0 0.2 Example 6 100 10 0.3 0.2 Example 7 100 30 0.3 0.2 Example 8 100 25 0.3 0.05 Comparative Example 1 100 0 0 0 Comparative Example 2 100 25 0 0 Comparative Example 3 100 40 0.3 0.2 Comparative Example 4 100 25 0.3 0.6 Comparative Example 5 100 25 0.03 0.2 Comparative Example 6 100 25 2.0 0.2 Comparative Example 7 100 5 0.3 0.2

≪ Evaluation of physical properties &

The polyoxymethylene resin compositions prepared in the above Examples and Comparative Examples were prepared by using an injection molding machine (Dongshin PRO-MC, 170T), setting the cylinder temperature at 195 占 폚 and the mold temperature at 60 占 폚 to obtain test specimens, And the results are shown in Table 2. The results are shown in Table 2. < tb > < TABLE >

(1) Tensile strength and tensile elongation: Measured according to ASTM D-638 standard.

(2) Flexural strength and flexural modulus: Measured according to ASTM D-790 standard.

(3) Impact strength: Measured according to ASTM D-256 standard.

(4) Shrinkage ratio: The specimens were stored at room temperature for 24 hours, and then the size difference was compared.

division The tensile strength
(kgf / cm ² ) Tensile elongation
(%) Flexural strength
(kgf / cm ² ) Flexural modulus
(kgf / cm ² ) Impact strength
(kg · cm / cm) Contraction ratio
(%) Example 1 438 60 820 40,900 5.5 1.2 Example 2 442 60 810 41,400 5.5 1.2 Example 3 440 65 820 41,200 6.0 1.2 Example 4 445 75 822 41,500 7.0 1.2 Example 5 440 70 820 40,700 6.3 1.2 Example 6 550 50 870 34,300 7.5 1.5 Example 7 408 70 780 42,500 5.0 1.1 Example 8 420 60 805 39,500 5.2 1.2 Comparative Example 1 630 40 925 27,500 8.5 2.0 Comparative Example 2 350 65 750 38,500 4.3 1.2 Comparative Example 3 375 75 725 45,800 3.0 1.0 Comparative Example 4 405 60 760 39,800 4.5 1.2 Comparative Example 5 380 70 800 37,500 4.0 1.2 Comparative Example 6 410 75 822 41,500 4.0 1.2 Comparative Example 7 580 45 895 29,700 7.3 1.8

As shown in Table 2, it was confirmed that the polyoxymethylene composition of Example 4 had the best balance between elongation and flexural modulus and the least impact strength loss. The shrinkage ratio was found to vary with the content of calcium carbonate rather than the effect of the coupling agent and the fatty acid ester. It was confirmed that the elongation and elastic modulus were measured to be low when the content of calcium carbonate was too low as in Comparative Example 7, It was confirmed that the impact strength loss was larger when the content was increased. In addition, when the fatty acid ester was added in excess as in Comparative Example 4, a phenomenon in which tensile strength and impact strength were deteriorated was confirmed.

On the other hand, it was confirmed that 0.3 parts by weight of the coupling agent added for improving the sliding property of the calcium carbonate and the polyoxymethylene resin, and 0.2 parts by weight of the fatty acid ester added for improving the releasability were most balanced properties . It was confirmed that when a coupling agent and a fatty acid ester were not added as in Comparative Examples 1 and 2 or a small amount of a coupling agent was added as in Comparative Example 5, the loss of impact strength was large and the balance of mechanical properties was not maintained. It was confirmed that the impact strength was remarkably lowered even when a large amount of coupling agent was added.

Claims (9)

10 to 30 parts by weight of calcium carbonate surface-treated with an organic acid, 0.05 to 0.5 parts by weight of a fatty acid ester and 0.05 to 1.0 part by weight of a coupling agent based on 100 parts by weight of polyoxymethylene.
The polyoxymethylene resin composition according to claim 1, wherein the calcium carbonate is heavy calcium carbonate having an average particle diameter of 1.0 to 2.0 탆.
The method of claim 1, wherein the organic acid is selected from the group consisting of saturated fatty acids including Lauric acid, Capric acid, Myristic acid, and Stearic acid; And an unsaturated fatty acid including oleic acid, linolic acid, and linolenic acid. The polyoxymethylene resin composition according to claim 1,
The method of claim 1, wherein the fatty acid ester is selected from the group consisting of glycerol monostearate, glycerol monobehenate, ethylene glycol stearate, propylene glycol stearate, sorbitan monostearate, Wherein the polyoxymethylene resin composition is at least one selected from the group consisting of Sorbitan monostearate and Sorbitan monobehenate.
2. The polyoxymethylene resin composition according to claim 1, wherein the coupling agent is at least one selected from a titanate series represented by the following formula (1) and a zirconate series represented by the following formula (2).
(Formula 1)

(2)

In the above formulas (1) and (2), R ₁ and R ₂ are independently

,

,

And

≪ / RTI >
The polyoxymethylene resin composition according to claim 1, wherein the polyoxymethylene has a weight average molecular weight (Mw) of 150,000 to 300,000 and a melting point of 165 to 172 ° C.
A molded article formed from the polyoxymethylene resin composition according to any one of claims 1 to 6.
The molded article according to claim 7, wherein the molded article has a tensile elongation of 50 to 80% as measured by ASTM D638 and an Izod impact strength of 5.0 to 8.0 kg.cm / cm as measured by ASTM D256.
The molded article according to claim 7, wherein the molded article has a flexural modulus of 34,000 kgf / cm ² or more and a shrinkage ratio of 1.5% or less as measured by ASTM D955, according to ASTM D790 measurement standard.