KR101169938B1 - Polyethylene/wood flour/clay nanocomposite - Google Patents

Abstract

An environmentally friendly HDPE / wood flour / clay nanocomposite with improved thermal and dimensional stability is disclosed. According to the present invention, the purpose is achieved by providing an HDPE / wood powder / clay nanocomposite prepared by melt mixing by adding polyethylene and a compatibilizer to an internal mixer, then mixing and melting clay, and then adding wood powder. do.

Description

Polyethylene / wood flour / clay nanocomposite manufacturing method {Polyethylene / wood flour / clay nanocomposite}

The present invention relates to a method for manufacturing environmentally friendly HDPE / wood powder / clay nanocomposites with improved thermal stability and dimensional stability, and more particularly, to introduce a new processing method (material) for the production of polyolefin / wood powder composites having poor thermal stability and dimensional stability. The present invention relates to a method for producing environmentally friendly HDPE / wood powder / clay nanocomposites, which improves the dispersibility of nanoclay and thus exhibits better thermal stability and dimensional stability than the prior art.

In recent years, the thermoplastic plastics industry, which is reinforced with various kinds of natural fillers due to a change in environmental and resource awareness, has received great attention. In particular, the WPCs (Wood Plastic Composites) industry is a composite material manufactured by mixing a suitable ratio of thermoplastic resins such as PP, HDPE, LDPE, PVC and natural fiber such as wood powder, and is widely used in various industrial fields such as building materials. WPC has been researched and developed to recycle environmentally friendly amount of sawdust from waste wood and solid wood used as building materials, and the processing method of melt blending wood powder into thermoplastic resin is studied.

As the industry develops highly, the demand for polymers is increasing rapidly, especially in construction and general household materials. These plastic materials are mainly used as a substitute for wood, and since then, a large amount of plastic materials have been widely used not only for building materials but also for wood use such as furniture manufacturing. Wood, a natural material, is not only expensive but unstable in supply and demand, and is also unfavorable in terms of environmental protection such as global warming, which is a recent global concern. Therefore, plastics and their composites are replacing many parts of wood.

WPC is a composite of wood flour and thermoplastic resin, and is mainly used as an external building material. Therefore, the physical properties of the product may be reduced by external moisture, ambient temperature, ultraviolet light, bacteria, insects, and the like. The dimensional stability, which is affected by temperature, is judged by the large and small strain of the original object when the object is heated, that is, when the temperature is increased. Dimensional stability should be good due to the small strain rate of dimension due to temperature change. Building materials will repeatedly expand and contract as the ambient temperature changes, which can lead to warpage and cracking. Plastics, which are organic materials, have lower specific gravity and easier processability than metals and inorganic materials, but most of them are organic materials composed of carbon, hydrogen, and oxygen, and are easily burned by fire. It has a weak back. Therefore, there is a growing interest in reducing human and property damage caused by plastic combustion and solving environmental problems derived from combustion gas or process. In order to reinforce the fragile flame retardant properties of these composites, simply mixing the flame retardant is effective in improving the flame retardancy, but the halogen-based flame retardant having high performance not only generates a large amount of highly corrosive halogens in high temperature processing or fire, but also oxygen Combustion under unfavorable conditions generates highly toxic carcinogens that are very harmful to the human body, and are currently regulated around Europe as environmental and human hazards. In addition, the addition of the flame retardant results in a decrease in the mechanical properties of the polymer resin itself. In the present invention, to improve the thermal stability and dimensional stability of the PE-based WPC composite by introducing a clay as a nano-filler to prepare HDPE / wood powder / clay nanocomposites to solve not only dimensional stability and thermal stability but also flame retardancy problems. In addition, HDPE / wood flour / clay nanocomposites were used to disperse nanoclays in molten HDPE resin using HDPE and compatibilizers, and to solve the problems raised above by sequentially melt-mixing wood powder. .

The present invention uses maleic anhydride grafted PE (MA-g-PE), which is a compatibilizer to increase the interfacial bonding force of hydrophilic wood flour and lipophilic polymer resin and improve the insertion and dispersibility of nanoclays. It was. In addition, the objective is to develop a WPC composite building material with improved thermal stability and dimensional stability through the optimal PE selection to increase nanoclay dispersibility in polymer matrix.

Therefore, the present invention uses the method used in the existing patent (WPC environmentally friendly polyolefin / wood powder composite), but the nanodispersion in the melted HDPE resin using high density polyethylene, not a variety of conventional polyolefin-based material in the material In order to overcome the problems of the prior art using a method of melt mixing the wood powder sequentially.

60 parts by weight of polyethylene in order to achieve the object of the present invention as described above; Wood flour 40 parts by weight; 3 parts by weight of a compatibilizer (MA-g-PE); Clay provides polyethylene / wood flour / clay nanocomposites consisting of 1 part by weight of total PE / wood flour / commercial agent (MA-g-PE), preferably HDPE and compatibilizer in an internal mixer at about 150 ° C., 60 rpm. The present invention provides a method for producing polyethylene / wood powder / clay nanocomposites prepared by melting and mixing clay after mixing under blending conditions, followed by melting by adding wood powder.

The HDPE / wood powder / clay nanocomposites produced by the present invention can be mainly used as interior and exterior building materials, and are excellent in mechanical strength, thermal stability, and dimensional stability, and are environmentally friendly. Since HDPE / wood flour / clay nanocomposites contain a large amount of wood powder, it can be used as waste wood or natural wood, which are not economical, and it is easy to secure materials by improving materials in process. As the importance of the environment has risen internationally, with the emergence of sick house syndrome and environmental hormones, consumers' interest in eco-friendly products has increased. This is driving the demand for HDPE / wood flour / clay nanocomposites. In this way, in addition to the costs incurred in the disposal, it is environmentally friendly in that waste wood can be used. HDPE / wood powder / clay nanocomposites have a texture and appearance similar to wood and have better processability than natural wood. Therefore, the HDPE / wood powder / clay nanocomposites according to the present invention can provide a product that not only satisfies consumer preferences, but also combines the advantages of natural wood and plastics.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

Example 1

Polyethylene (HDPE) used in the present Example was used as the main material of SK Energy's HDPE (JH-910, melt flow index = 8.5g / 10min, density = 0.963g / cm ³ ), 70 ~ 150㎛ 40 parts of wood flour of size (Lignocel C-120 from J. Retenmaier & Sohne Co.) were used after removing water from an oven at 100 ° C for 1 hour. , maleci anhydride contents = 1wt%, melt flow index = 2.0g / 10min), and the layered mineral clay is montmorillonite (MMT), and modified MMT modified with Cloisite 20A (dimethyl dihydrogenated tallow 2-ethylhexyl ammonium from Nanoclay, USA). ) 1 part by weight was used.

For polyethylene / wood powder / clay nanocomposite specimens, HDPE and a compatibilizer (MA-g-PE) were added into an internal mixer, followed by mixing for 4 minutes at 150 ° C and 60 rpm in melt blending conditions. Then, the mixture was sufficiently melted for 20 minutes, and then the wood powder was added and melt mixed for 6 minutes from the internal mixer, placed between hot presses, and the panel was manufactured by compression molding. Specimens for thermal analysis (TMA and TGA) tests were made by cutting panels. Each material was dried in an oven and placed in an internal mixer.

Comparative Example 1

Clay-free polyethylene / wood flour WPC was prepared for comparison with Example 1. As in Example 1, polyethylene (HDPE) was used as the main material of SK Energy's HDPE (JH-910, melt flow index = 8.5 g / 10 min, density = 0.963 g / cm ³ ) as a main material. 40 parts by weight of wood flour (Lignocel C-120 from J. Retenmaier & Sohne Co.) was used after removing water for 1 hour in an oven at 100 ° C. , maleci anhydride contents = 1wt%, melt flow index = 2.0g / 10min), but no clay.

 Polyethylene / wood powder WPC specimens were mixed with HDPE and a compatibilizer (MA-g-PE) in an internal mixer and mixed well until the torque was stabilized under melt blending conditions at 150 ° C and 60 rpm. Insert and melt-mix for 6 minutes as in Example 1. The molten mixture was removed from the internal mixer and placed between hot presses to produce panels by compression molding. Specimens for thermal analysis (TMA and TGA) tests were made by cutting panels. Each material was dried in an oven and placed in an internal mixer.

Mechanical strengths of the polyethylene / wood flour / clay nanocomposites (WPC + Closites20A in figures 1, 2, 3 and 4) of Example 1 and the polyethylene / wood flour WPC composites (WPC of figures 1, 2, 3 and 4) of Comparative Example 1 The analysis was measured using UTM and the results are shown in FIG. 1. Thermal stability was measured using a thermal analyzer (TGA) and the results are shown in FIG. 2, and dimensional stability was measured using a thermal analyzer (TMA), and the results are shown in FIGS. 3 and 4. It can be seen that the mechanical strength and thermal stability and dimensional stability of the polyethylene / wood flour / clay nanocomposites of Example 1 are much better than the mechanical strength, thermal stability and dimensional stability of the polyethylene / wood flour WPC composite of Comparative Example 1. In addition, the preparation of the polyethylene / wood flour / clay nanocomposite of Example 1 (WPC + Closites20A of FIGS. 1, 2, 3, and 4) was performed in the polyethylene / wood flour WPC composite of Comparative Example 1 (WPC of FIGS. 1, 2, 3, and 4). Compared to the production of nano-sized clay was used and the results are shown in Figures 1, 2, 3, 4. It can be seen that Example 1 is more excellent in mechanical strength, thermal stability and dimensional stability of Comparative Example 1.

That is, FIG. 1 is a graph of mechanical strength test (UTM, Universal testing machine) results of polyethylene / wood flour (WPC) of Comparative Example 1 and polyethylene / wood flour / clay (WPC + Closites20A) nanocomposite sample of Example 1 Flexural strength according to the present invention is shown, the flexural strength of the polyethylene / wood powder / clay (WPC + Closites20A) nanocomposite according to the present invention, the flexural modulus (Flexsural modulus) of the polyethylene of Comparative Example 1 It can be seen that the value is higher than / wood powder (WPC), from which the mechanical strength is improved by the introduction of nano-sized clay.

2 is a graph of thermal analysis (TGA, Thermogravimetric Analysis) results for the polyethylene / wood powder (WPC) of Comparative Example 1 and the polyethylene / wood powder / clay (WPC + Closites20A) nanocomposite sample of Example 1 It shows the weight loss according to the weight loss of the polyethylene / wood powder / clay (WPC + Closites20A) nanocomposite according to the present invention can be seen that occurs at a higher temperature than the polyethylene / wood powder (WPC) of Comparative Example 1 From this it can be seen that the thermal stability is improved by the introduction of nano-sized clay.

FIG. 3 is a graph of thermal analysis (TMA, Thermomecanical Analysis) results of polyethylene / wood flour (WPC) of Comparative Example 1 and polyethylene / wood flour / clay (WPC + Closites20A) nanocomposite sample of Example 1 As a change, it can be seen that the change of the dimension according to the temperature change of the polyethylene / wood powder / clay (WPC + Closites20A) nanocomposite according to the present invention is smaller than the polyethylene / wood powder (WPC) of Comparative Example 1 from this nano-size It can be seen that the dimensional stability is greatly improved by the introduction of clay.

In addition, Figure 4 summarizes the thermal expansion coefficient and dimensional change obtained from the thermal analysis experiment results of the polyethylene / wood powder (WPC) of Comparative Example 1 and polyethylene / wood powder / clay (WPC + Closites20A) nanocomposite of Example 1 (Fig. 2) As a table, when looking at the table, the clay was introduced to obtain a thermal expansion coefficient of 76.1 µm / m ° C (Comparative Example 1) at -30 ° C to 66.9 µm / m ° C (Example 1), and 40 ° C at 124 µm / m. It can be seen that 81.8 μm / m ° C. (Example 1) was greatly reduced at ℃ (Comparative Example 1), and in the case of dimensional change at −30 ° C. and 40 ° C., 0.81% (Comparative Example 1) to 0.73% (Example As a result, the dimensional stability was greatly improved by introducing clay.

Therefore, variables affecting the mechanical strength, thermal stability and dimensional stability of HDPE-based WPC nanocomposites include melt flow index, wood powder content and type, additive content and melt flow index, working temperature, There may be the retention time in the extruder, the presence and absence of clay, and the content, but the same method as the existing patent is used, but the nano-sized clay is a variable that affects the mechanical strength, thermal stability, and dimensional stability rather than the environmentally friendly flame retardant. The presence or absence of the most likely to have the biggest impact. The dimensional stability will be further improved when clay, which is a layered inorganic compound, is well dispersed in a thermoplastic resin matrix to prepare a nanocomposite in which the layer is separated.

1 is a graph of the mechanical strength test results of the comparative example and the present invention composite.

Figure 2 is a graph of the thermal analysis experiment results of the comparative example and the present invention (weight reduction).

Figure 3 is a graph (dimension change) of the thermal analysis experiment results of the comparative example and the present invention composite.

4 is a coefficient of thermal expansion and dimensional change theorem obtained from FIG.

Claims (1)

Polyethylene (HDPE) / wood powder / clay nanocomposite manufacturing method, the internal mixer 60 parts by weight of the melt flow index (8.5 g / 10 minutes) polyethylene and a compatibilizer (melt flow index 2.0 g / min) 3 parts by weight of g-PE) was mixed for 4 hours at a melt blending condition of 150 ° C. and 60 rpm. Then, 1 part by weight of nano clay, which was 1 part by weight of the total amount of polyethylene / wood powder / compatibility agent, was added and melted for 20 minutes. Polyethylene / wood powder / clay nanocomposite manufacturing method, characterized in that the size of ˜150㎛ and 40 parts by weight of wood powder removed from water for 1 hour at 100 ° C., followed by melt mixing for 6 minutes.

Images