KR100740487B1 - Nylon 6 nanocomposites - Google Patents

Abstract

The present invention relates to a nylon 6 nanocomposite, wherein a maleic hydride-grafted coupling agent and a dialkyltriamine type organic agent are introduced to introduce nanoclays whose surface is modified so that the ratio of? Crystals is 50 to 80%. The present invention provides a nylon 6 nanocomposite resin having improved structural properties compared to conventional nylon 6 nanocomposites, thereby improving deterioration in elongation and impact characteristics.

Nanoclay * Dialkyl Triamine * Organic Agent * Maleic Anhydride * Graft * Coupling Agent * Nanocomposite

Description

Nylon 6 nanocomposites {Nylon 6 nanocomposites}

The present invention relates to a nylon 6 nanocomposite, and more particularly, to a nylon 6 nanocomposite which improves elongation and impact properties by giving structural changes to increase the γ-crystallization ratio of nylon 6.

The nanocomposite manufacturing technology using nanoclay is to limit the low mechanical properties of general-purpose polymers such as polyethylene and polypropylene by dissolving the silicate layered clay mineral into the base unit on the nano scale sheet and dispersing it in the polymer resin. The concept to be raised is included.

However, plate silicates, which are the basic units of clay minerals, are very difficult to peel and disperse in polymer resins. In order to solve this problem, low molecular weight emulsifiers are inserted between clays to widen the gap between plate silicates to facilitate the penetration of polymer resins. Peel off and disperse by making them.

This nanocomposite technology was first developed by Toyota Motor in Japan in 1987. The surface of the inorganic filler, which was added to improve the mechanical and thermal properties of various plastic materials, was treated with various organic agents. By improving the dispersibility of the existing inorganic filler by about 100 to 1,000 times, even if a small amount of inorganic material is added, the stiffness and heat resistance that can be obtained only by adding a large amount of the inorganic filler can be obtained.

The methods of separating clay minerals into basic units on a nano scale sheet and dispersing them in a polymer resin are largely classified into a solution method, a polymerization method, and a compounding method. The double polymerization method and the compounding method are based on the 80s and 90s, respectively. Research has progressed and now it is in the commercialization stage in western developed countries including the United States and Japan.

Among these, compounding is a recently developed dispersion and peeling technique. Unlike a solution or polymerization method, a polymer sheet is dispersed between clay silicate layers and mechanically mixed to disperse the clay sheet. In 1995, Cornell University's research team developed the interlayer composite by inserting polystyrene melt directly. In 1997, the research center of Toyoda, Japan announced the development of a peelable polypropylene nanocomposite by compounding method. It is the latest technology. This technique is to improve the mechanical and thermal properties of the base polymer, and the conventional inorganic fillers, which are generally added during compounding, are agglomerated and dispersed in the polymer with a particle size of 1 μm or more, so that the mechanical and thermal properties of the base polymer are increased. It is a technology developed to improve the disadvantage that the improvement of the characteristic is weak.

Specifically, the surface of the added inorganic material is surface-treated with various organic agents consisting of a head group and a tail group of cationic nature to enhance the usability with high molecules, thereby dispersing the inorganic filler to the nanoscale. It is a peeling and dispersing technology that makes up for the shortcomings of existing inorganic filler composites.

At this time, specific examples of the organic agent include alkylamine types such as propylamine, butylamine, octylamine, decylamine, dodecylamine, hexadecylamine, octadecylamine, N-methyloxadedecylamine; Methylamine hydrochloride, tetramethylammonium chloride, octadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, dioctadecyldimethylammonium bromide, dimethylbenzyloctadecylammonium bromide, bis (2-hydroxylethyl) methyl Alkylammonium halide types such as octadecyl ammonium chloride, 1-hexadecylpyridium bromide; Alkylaminoacid types such as 6-aminohexanoic acid and 12-aminododecanoic acid; And alkyldiamine types such as 1,6-hexamethylenediamine and 1,12-dodecanediamine.

Looking at one example of the preparation of the polymer nanocomposite, Japanese Patent Publication Nos. 60-108463 and 60-47061 disclose that the surface-treated clay and glass fibers only with a silane coupling agent are added to the polyamide resin composition to give the polyamide resin rigidity. A technique for improving heat resistance and heat resistance is disclosed. However, since the surface of the clay is not modified as the organic agent mentioned above, the dispersibility of the clay is insufficient, so that the rigidity and heat resistance are improved, but the specific gravity is high, the flowability is decreased, and the elongation and impact strength are also sharply dropped. .

In order to overcome this problem, U.S. Pat.Nos. 4,739,007, 4,810,734 and Japanese Patent Publication No. 76-109,998 disclose polymerized nylon nanos modified with clay monomers after modification of the clay surface with the above-described alkylaminoacid type organic agent. The composite material was prepared, but this did not improve the disadvantages of greatly reducing elongation and impact characteristics.

On the other hand, US Patent No. 4,874,728 uses clays whose surface is modified with an alkylamino type organic agent and a coupling agent such as alkoxy or acetoxy or halosilyl-based organosilane, but this also does not improve elongation and impact characteristics. I couldn't.

As described above, the nylon-based nanocomposite material developed to date using nanocomposite technology has the characteristics of expressing excellent stiffness and heat resistance even with the addition of a small amount of inorganic material, but elongation and impact strength are conventional. There is a drawback that is significantly lower than the inorganic filler material is currently being limited in many applications.

Thus, the inventors of the present invention while trying to solve the problem of falling elongation and impact strength in the nylon-based nanocomposites as described above, as a result of increasing the content of γ crystals of nylon 6, the elongation and impact characteristics It has been found that the deterioration can be improved to complete the present invention.

Accordingly, it is an object of the present invention to provide a nylon 6 nanocomposite having improved elongation and impact characteristics by giving a structural change to increase the content of γ crystals of nylon 6.                         

The nylon 6 nanocomposite of the present invention for achieving the above object is obtained by adding a clay mineral and a coupling agent surface-treated with an organic agent to the nylon 6 resin, which is a ratio of γ crystals of 50 to 80% It features.

The present invention will be described in more detail as follows.

The present invention relates to a nylon 6 nanocomposite that improves elongation and impact property degradation by giving a structural change to increase the content of γ crystals of nylon 6.

The nanocomposite of the present invention is introduced with a nanoclay surface modified with a maleic hydride-grafted coupling agent and a dialkyltriamine type organic agent, and the specific composition is as follows.

(1) coupling agents grafted with maleic anhydride

The coupling agent is used for the purpose of enhancing compatibility between the nylon polymer 6, which is a base polymer, and the nanoclay, an inorganic filler added for high stiffness expression. Specifically, the coupling agent has a surface of the inorganic material on an olefin oligomer resin having a number average molecular weight of 10,000 or less. Use a grafted maleic anhydride that can chemically bond to the base resin nylon 6 resin.

At this time, when the number average molecular weight of the olefin oligomer resin is greater than 10,000, compatibility with nylon 6 resin, which is a base polymer, is poor, and elongation and impact characteristics are lowered.

The content of maleic anhydride treated on the surface of such an olefin oligomer resin is 1.0% by weight or less of the total coupling agent. Specifically, in the examples of the present invention, the product name "Epolene C-18" having a number average molecular weight of 5,700. (Hereinafter referred to as C-18).

However, the coupling agent which can be used in the present invention is not limited to C-18 only.

The addition amount of the coupling agent is preferably 0.5 to 5% by weight of the total composition. If the addition amount is less than 0.5% by weight, the addition amount is insignificant and the effect of improving elongation and impact strength is insufficient. The purpose as a nanocomposite cannot be achieved.

(2) Nanoclay

The nanoclay used in the present invention uses nanocracks whose surface is modified with a dialkyltriamine type organizing agent, and the reason is that the dialkyltriamine type organizing agent is reactive as represented by the following formula (1). There is an excellent amine group, and the coupling agent used in the present invention is characterized by excellent reactivity with the maleic hydride group.

H ₂ N (CH ₂ ) _m NH (CH ₂ ) _n NH ₂

Wherein m and n are the same as or different from each other and are integers of 3 to 10.

The addition amount of such nanoclays is preferably 2 to 10% by weight of the total nanocomposites. If the content of nanoclays is less than 2% by weight, it is difficult to obtain high flexural modulus expressed due to the excellent dispersibility of the nanoclays. If it is difficult and more than 10% by weight, elongation and impact resistance are poor.

(3) nylon 6 resin

Nylon 6 resin used as a base film in this invention has 80-60% of alpha crystals, and 20-40% of gamma crystals normally. The ratio of α, γ crystals does not change in general nanocomposites.

However, when the above-mentioned coupling agent and nanoclay are applied, the ratio of γ crystals is increased to 50 to 80%, and together with these results, physical properties such as elongation and impact strength of the nylon 6 nanocomposite are excellent.

The extruder used to prepare the inorganic reinforced nylon 6 nanocomposite of the present invention having the composition as described above may be a twin screw extruder, and may be prepared at a temperature of 245 ° C. to 255 ° C. of the cylinder barrel. In order to maximize the physical properties of the resin composition, it is preferable to add a nylon 6 resin and a coupling agent to the primary inlet by using an extruder having three inlets, and nanoclay to the secondary inlet.

In addition, in order to maximize the physical properties of the composition during melt kneading, it is desirable to minimize the residence time, and to install a decompression device called vent near the discharge part to reduce the gaseous low molecular material generated during melt kneading by reducing the pressure to 150 mmHg or less. It is effective to remove.                     

On the other hand, a thermal stabilizer (for example, IRGANOX B1171), a mold release agent, a weathering agent, a pigment, etc. can be added within the range which does not violate the objective of this invention.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

On the other hand, the physical property evaluation criteria for the obtained nanocomposites are as follows.

1) Elongation: After making a 1/8 '' dumbbell type specimen in accordance with ASTM D638, the tensile elongation measurement rate was set to 50mm / min.

2) Impact strength: Izod Notched impact strength was measured at room temperature by making 1/4 '' specimens in accordance with ASTM D256.

3) Flexural modulus: After fabricating a 1/4 '' specimen according to ASTM D790, the flexural modulus was measured at 5 mm / min.

4) X-ray diffraction analysis:

Equipment RIGAKU, Japan

Model Name D / Max 3B,

X-ray wavelength used (λ)-1.5406 GHz

Equatorial Scanning from 10 to 35 °

Examples 1-4

Next melted and kneaded in a twin screw extruder heated to 245 ℃ according to the composition and content of Table 1 to make a chip (chip) and dried using a 90 ℃, 5 hours dehumidification dryer, and also using a heated screw injection machine Each specimen was prepared at the same temperature as that of melt kneading, and the evaluation was carried out by the evaluation method as described above. The evaluation results are shown in Table 2 below.

(Unit: weight%) Nylon 6 Coupling Agents ⁽¹⁾ Nanoclay ⁽²⁾ (n) Example 1 94 2 4 (3) Example 2 90 2 8 (3) Example 3 92 4 4 (6) Example 4 88 4 8 (6) (1) Coupling agent: Olefin-based oligomer resin having a number average molecular weight of 5,700 and a maleic anhydride of 1.0 wt% or less, produced by Eastman, Epolene C-18 (2) Nanoclay: H ₂ N ( CH ₂ ) _n organic clay with _n NH (CH ₂ ) _n NH ₂

Elongation (%) Impact Strength (kgcm / cm) Flexural modulus (kg / ㎠) α crystal ratio (%) γ determination rate (%) Example 1 11.5 8.5 45100 35 65 Example 2 8.5 7.3 57800 28 72 Example 3 14.7 10.3 46300 33 67 Example 4 13.7 10.1 55900 24 76

Comparative Examples 1 to 4

Comparative Examples 1 to 4 are examples of cases in which the nanocomposite composition is outside the scope of the present invention, and the resin composition is shown in Table 3 below, and the physical properties were evaluated in the same manner as in Example, and the results are shown in Table 4 below. Indicated.

(Unit: weight%) Nylon 6 Coupling Agents ⁽¹⁾ Nanoclay ⁽²⁾ A B Comparative Example 1 96 - 4 - Comparative Example 2 92 - 8 - Comparative Example 3 94 2 - 4 Comparative Example 4 88 4 - 8 (1) Coupling agent: Olefin-based oligomer resin having a number average molecular weight of 5,700 and maleic anhydride of 1.0 wt% or less, produced by Eastman, Epolene C-18 (2) Nanoclay A: H ₂ N Clay nanoclay organically treated with (CH ₂ ) ₆ NH (CH ₂ ) ₆ NH ₂ : clay organicized with H ₂ N (CH ₂ ) ₁₅ CH ₃

Elongation (%) Impact Strength (kgcm / cm) Flexural modulus (kg / ㎠) α crystal ratio (%) γ determination rate (%) Comparative Example 1 5.6 6.5 26300 75 25 Comparative Example 2 4.9 5.2 27400 70 30 Comparative Example 3 3.3 4.7 24700 72 28 Comparative Example 4 4.4 4.6 29500 65 35

From the results of Tables 2 and 4, in the case of the nylon 6 nanocomposite according to the present invention, the γ crystal content was increased compared to the nylon 6 resin, and elongation and impact strength were also not added with a coupling agent or organically treated with a conventional alkylamine. It can be seen that the improvement compared to the applied clay.

As described in detail above, the nylon 6 nanocomposite incorporating the nanoclay surface-modified with a coupling agent and a dialkyltriamine type organic agent grafted with maleic anhydride according to the present invention has a content of? Crystals. Along with the increased structural changes, it is possible to improve the degradation of elongation and impact characteristics, which is a disadvantage of the conventional nylon 6 nanocomposite.

Claims (4)

In the nylon 6 nanocomposite, Includes clay minerals surface-treated with an organic agent, coupling agents and nylon 6 resins, The nanocomposite is nylon 6 nanocomposite, characterized in that the ratio of the γ crystal is 50 to 80%. The nylon 6 nanocomposite of claim 1, wherein the nanocomposite has an elongation of 7.0 to 20.0%, an impact strength of 7.0 to 12.0 kg · cm / cm, and a flexural modulus of 40000 to 60000 kg / cm 2. According to claim 1, wherein the clay mineral surface-treated with an organic agent is a nanoclay surface modified with a dialkyltriamine type organic agent represented by the following formula (1), the content is 2 to 10% by weight of the total nanocomposite Nylon 6 nanocomposite, characterized in that. Formula 1 H ₂ N (CH ₂ ) _m NH (CH ₂ ) _n NH ₂ Wherein m and n are the same as or different from each other and are integers of 3 to 10. The nylon 6 nanocomposite according to claim 1, wherein the coupling agent is an olefin oligomer resin grafted with maleic anhydride, the content of which is 0.5 to 5% by weight of the total nanocomposite.