KR101715317B1 - Foam composition and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a foam composition and a method for preparing the same. Particularly, the present invention relates to a high density polyethylene-kenaf fiber foam composition to which thermally expandable microcapsules are applied. The foam composition can be processed to have eco-friendly characteristics and a low weight and thus applied to a material for a car interior part. The foam composition comprises a high density polyethylene (HDPE)-kenaf fiber (KF) composite. Thermally expandable microcapsules (EMC) are applied to the HDPE-kenaf fiber composite. More particularly, the foam composition comprises PE-g-MAH having a graft ratio larger than 1.40 as a compatibilizer so that the compatibility of the HDPE-kenaf fiber composite may be optimized to improve mechanical properties and the foaming efficiency may be maximized when EMC as a foaming agent is applied to the HDPE-kenaf fiber composite for the purpose of foaming.

Description

[0001] FOAM COMPOSITION AND MANUFACTURING METHOD OF THE SAME [0002]

The present invention relates to a foam composition and a process for preparing the same, and more particularly to a high density polyethylene (HDPE) -natural fiber foam composition. In the foam composition, a thermally expandable micro capsule (EMC) is applied to a high density polyethylene (HDPE) which is relatively easy to foam in polyolefin, thereby realizing weight reduction by foaming and as a reinforcing agent To a foam composition employing environmentally friendly natural fibers and usable as an environmentally friendly lightweight material for automobile interior materials.

First, there is a reduction in the weight of automobile interior / exterior parts. Second, in terms of total carbon management, the use of natural materials with low CO ₂ generation during production and disposal, . ≪ / RTI > As a result, if it is possible to manufacture lightweight parts using natural materials to improve fuel efficiency and reduce exhaust gas emissions, it can be said that the most environmentally friendly part is a natural material. Natural fiber reinforced plastics , NFRP).

Composite materials widely used in various industries include glass fiber reinforced plastics, which are made of thermoplastic and thermosetting resin as matrix and reinforced with glass fiber. In the 1940s, glass fibers were applied together with unsaturated polyester And has been utilized in various industrial fields such as automobile, shipping industry such as ship, sporting-leisure, electronic material, defense material. However, glass fiber, which is used as a reinforcing agent for glass fiber reinforced composite materials, is not easily decomposed in a natural environment, and has a high specific gravity. Therefore, when applied to automobile parts, it has problems such as reduction of fuel consumption and increase of carbon dioxide emission. Also, due to the generation of glass dust during work, it is harmful to the human body of the worker and it is difficult to recycle. Therefore, the use of such materials is being restricted with the change in social awareness of the environment,

Luft und Raumfart Institute of Structural Mechanics는 Kenaf(양마), flax(아마), hemp(대마), ramie(모시) 등의 천연섬유(natural fiber)를 고분자수지의 보강섬유로 도입한다는 획기적인 방법을 제안했고, 기존에 사용되던 유리섬유 복합소재에 버금가는 물성을 구현하여 천연섬유 고분자 복합소재의 근간을 마련하였다. 현재 실용화에 대한 연구를 주로 실행하고 있는 기업체들은 천연섬유 복합재료를 자동차의 내장재와 외장재로 적용하여 고성능 바이오 복합재료를 개발하기 위해 노력하고 있다. To solve these shortcomings, Deutsches Zentrum

The Luft und Raumfart Institute of Structural Mechanics proposed a groundbreaking method of introducing natural fibers such as kenaf, flax, hemp and ramie into reinforcing fibers of polymer resins, It is similar to the conventional glass fiber composite material and realizes the basis of natural fiber polymer composite material. Companies that are currently conducting practical research are trying to develop high-performance biocomposites by applying natural fiber composite materials to automobile interior and exterior materials.

For example, Mercedes-Benz, Germany, is actually applying natural fiber composite materials to interior materials and exterior materials of passenger cars, and is actively pursuing derivatives research that apply them to buses and trains. In Asia, studies are mainly conducted in Korea, Japan, China, and India, and Japan is actively pursuing R & D and commercialization. For the practical use of natural fiber composite materials, Japanese Toyota Motor Company applied natural fiber composite materials made of Kenaf and polylactic acid (PLA) to passenger cars for the first time in 2005. In 2007, the i-Unit concept using Kenaf The car was presented at the exhibition.

In the domestic patent application No. 10-2007-7021840, there is proposed a method of using natural fibers made of thermoplastic fibers, thermoplastic organic fibers and natural fibers as reinforcing fibers, mixing them in various composition ratios to form multi-layers, And Korean Patent Application No. 10-2009-0041887 discloses a method of mixing a synthetic fiber and a natural fiber in a continuous thermoplastic polyolefin foam sheet and a thermosetting polyolefin foam sheet using a heat roller Layered structure including a reinforcing layer in the form of a thin sheet having improved densities and a method of manufacturing the same, and a high-performance biocomposite material is being developed by applying a natural fiber composite material to automobile interior and exterior materials.

In addition to the application of eco-friendly materials for such automotive parts, it is necessary to make efforts to develop the required technologies for weight reduction. One of the key technologies is polyolefin foaming technology, which is relatively easy to foil among polyolefins. This is underway. HDPE is one of the most widely used plastic materials in the world and is harmless to the human body, has excellent chemical stability, low cost, easy processing and excellent mechanical properties. Is also widely used.

On the other hand, kenaf fibers (kenaf, jute, hemp, and flax), which are natural fibers, have properties comparable to glass fibers used as reinforcing agents for conventional composites and are suitable for manufacturing lightweight materials because of their low density, It is an environmentally friendly material because it is easy to decompose in nature.

However, when natural fibers are used as reinforcing agents in HDPE, compatibility between the two materials can be the biggest problem as mentioned above. When the compatibility between HDPE, which is a non-polar material, and natural fiber, which is a polar material, is lowered, the two materials work individually and act as a negative factor in foaming with a decrease in mechanical properties.

In order to solve such a problem, the commercialization of PE-g-MAH, which is produced and sold commercially, has resulted in the improvement of compatibility with HDPE / Kenaf composite with a relatively low content of hemp fiber (15 wt% or less) However, the improvement of mechanical properties and foaming behavior was not enough due to insufficient improvement of compatibility in composites with higher fiber content.

Therefore, there is a need to study materials that are eco-friendly materials applied to automobile parts and have improved mechanical properties and foaming behavior for use as automobile parts.

The present invention relates to a foam composition and a method for producing the same.

An object of the present invention is a high density polyethylene-natural fiber foam composition comprising 20% by weight or more of natural fibers sufficient for mechanical properties and foaming rate to be applied to automobile parts.

Another object of the present invention is to provide a high-density polyethylene-natural fiber foam composition employing EMC, which can control the specific gravity of the foam composition by 15% or lower relative to conventional HDPE to 0.8 g / 10 min or less, .

In one embodiment of the present invention, a composite material containing high density polyethylene (HDPE) and natural fibers, polyethylen-g-maleic anhydride (PE-g-MAH) and thermally expandable microcapsules (EMC) ≪ / RTI >

In one embodiment of the present invention, the compatibilizer polyethylene-g-maleic anhydride (PE-g-MAH) relates to a foam composition having a graft rate of greater than 40% but less than 50%.

In one embodiment of the invention, the natural fibers are from 15 to 50% by weight, based on the total weight of the foam composition.

In one embodiment of the present invention, the thermally expandable microcapsule (EMC) is 1 to 10% by weight based on the total weight of the foam composition, and the foam composition has a specific gravity of 0.8 or less.

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Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art, and the following embodiments can be modified into various other shapes, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In the drawings, the thickness and size of each layer are exaggerated for convenience and clarity of description, and the same reference numerals refer to the same elements in the drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, a singular form may include a plurality of shapes, unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

(PE-g-MAH) and thermally expandable microcapsules (EMC), which are compatibilizers, as well as high-density polyethylenes (HDPE) ≪ / RTI >

The polyethylene can be classified into HDPE, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and the like in which the density can be controlled according to the molecular structure. In the case of HDPE, And the mechanical properties are good because of its high degree of crystallization due to its molecular structure and its use as an automobile interior material is increasing.

The thermally expandable microcapsule is sealed by putting a liquid, a solid or a gas called a nuclear material inside a minute container. When heated above the softening point of the polymer, the polymer is softened to increase the vapor pressure of the contained expanding agent, This is the principle that expands. Expansion may not occur depending on the heating temperature, pressure, time, etc., and if the processing conditions are excessive, the expanded capsules may shrink, coalesce and collapse may occur, and it is very important to select the optimum processing conditions for each resin. EMC is effective for the lightweight, cushioning, insulation, insulation, elastic (anti-shrinkage) and anti-vibration properties of plastics, and it can be applied to existing physical foams or chemical foams To a competitive foaming system capable of minimizing surface deterioration and problems caused by residual foaming agents.

In one embodiment of the present invention, the natural fibers are at least one selected from the group consisting of hemp fibers, sisal fibers, and bamboo fiber fibers, and the hemp fibers include, for example, kenaf, jute Jute, Hemp, and Flax, and are not limited to the examples. The natural hemp fibers are polar polymers containing cellulose as a main component, and the cellulose base is characterized by excellent dimensional stability at a high temperature and high heat resistance. Also, since it is an environmentally friendly material that can be decomposed by nature, it reduces the possibility of environmental pollution.

In one embodiment of the present invention, the compatibilizer polyethylene-g-maleic anhydride (PE-g-MAH) has a graft rate of more than 40% but less than 50%. Grafting means "grafting." Grafting is the binding of a polymer chain to a polymer chain. Radiation is applied onto the polymer chains or active sites are formed by a catalyst or the like to thereby initiate polymerization of other monomers to synthesize a graft polymer. By graft polymerization of another monomer to a polymer material such as fiber or plastic, a material having new properties can be produced. That is, the graft rate indicates the degree of MAH graft in PE-g-MAH.

Therefore, when a commercialized PE-g-MAH having a low grafting rate is applied, a composite material having a high content of natural fibers is not sufficiently improved in compatibility, and mechanical properties and foaming characteristics are not improved to the required levels there is a problem. Concretely, when the graft ratio is less than 40%, the sufficient compatibilizing effect is not exhibited. When the grafting rate is 50% or more, the mechanical properties are deteriorated by PE-g-MAH which is a compatibilizer.

In one embodiment of the present invention, the natural fibers are 15 to 50 wt%, preferably 20 to 50 wt%, based on the total weight of the foam composition. When the natural fiber is contained in an amount of less than 15% by weight based on the total weight of the foam composition, the mechanical properties are deteriorated. When the natural fiber is contained in an amount of less than 50% by weight, , There is a problem that the profit on the cost is not large.

In one embodiment of the present invention, the heat-expandable microcapsule (EMC) is 1 to 10% by weight based on the total weight of the foam composition, and the specific gravity of the foam composition is 0.8 or less.

The present invention relates to an automobile parts material including the foam composition. The foam composition comprises a composite material comprising high density polyethylene (HDPE) and natural fibers, polyethylen-g-maleic anhydride (PE-g-MAH) and thermally expandable microcapsules (EMC) Unlike PE-g-MAH, which has a conventional grafting rate of 40% or less, mechanical properties and foaming ratio can be applied to automobile parts materials even when applied to a composite material containing 20% by weight or more of natural fibers.

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In one embodiment of the present invention, there is provided a method for producing a polyolefin resin composition, comprising the steps of 1) reaction extrusion of polyethylen-g-maleic anhydride (PE-g-MAH) The present invention relates to a method of making a foam composition comprising mixing a composite material and a thermally-expandable microcapsule (EMC), comprising PE-g-MAH, high density polyethylene (HDPE) and natural fibers.

The present invention applies a PE-g-MAH having a graft ratio of more than 40% as a compatibilizer for environmentally friendly and light weight of automobile interior materials, and has not only mechanical properties suitable for automobile interior parts material but also lightweight Eco-friendly high density polyethylene-natural fiber-thermally expandable microcapsule composite material. In addition, problems such as appearance problems, residual foaming agents, and expensive facilities that are generated in the conventional physical foaming and chemical foaming methods can be solved by applying EMC.

Figure 1 relates to commercialized PE-g-MAH and infrared spectra of PE-g-MAH prepared via reactive extrusion.
2 shows the change in the specific gravity of the compatibilizer and the content of natural fiber Kenaf fibers in the present invention.
Fig. 3 shows the change in stress according to the type of compatibilizer and the content of natural fiber Kenaf fiber in the present invention.
4 is a SEM photograph of the type of compatibilizer and the content of natural fiber, kenaf fiber, in the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the accompanying drawings, in which: Fig.

Figure 4 is a cross-sectional view of a cell of a HDPE-Kenaf-EMC foam with a commercialized PE-g-MAH according to the present invention as a compatibilizer and containing 15 wt% or more of kenaf on a weight basis , And that the foam cell formation is hardly achieved when the content of kenaf exceeds 17 wt%.

As shown in FIG. 4, the commercialized PE-g-MAH is not enough for grafting 40%, so it is commercialized in HDPE-kenaf complex containing 17 wt% or more of kenaf The reason for this is that the interfacial adhesion property of PE-g-MAH is weak and Kenaf acts as a different material in HDPE and does not play a sufficient role as a reinforcing agent.

Therefore, in order to improve the mechanical properties of HDPE and HDPE-kenaf composites composed of high-content kenaf fibers of more than 15 wt% as reinforcing agents, it is necessary to introduce a compatibilizing agent capable of sufficiently improving interfacial adhesion properties For this, the degree of MAH graft is important. Thus, PE-g-MAH having a MAH grafting degree exceeding 40% was prepared through reactive extrusion using a twin-screw extruder according to an embodiment of the present invention.

Measurement of MAH graft

The measurement of the degree of grafting of PE-g-MAH was carried out by measuring the C (C) peak at around 1,700 cm ^-1 of the CH stretching vibration peak appearing near 3,000 cm ^-1 in the spectrum measured using an infrared spectrometer (Perkin Elmer's FT-IR spectrum 1000) = O stretching vibration peak.

Fig. 1 shows an infrared spectroscopic spectrum for measuring the degree of grafting of PE-g-MAH used as a compatibilizer. 1, the graft rate of the PE-g-MAH produced through the reaction extrusion using the biaxial compressor according to an embodiment of the present invention is 44% to be.

HDPE - Natural Fiber - Evaluation of Physical Properties of EMC Foam

[Example 1]

Using dicumyl peroxide (DCP), MAH and HDPE using a twin-screw extruder (effective length (L / D) = 40 cm / 11 mm), the biaxial extruder temperature was changed from 160-220 at PE- -MAH. At this time, the MAH / DCP molar ratio is 1: 3, and the MAH is adjusted to about 44% in the graft. Then, the HDPE-yam fiber composite was extruded under the conditions of 180/170/160/150/140/140 with a sheep fiber content of 20% by weight and a PE-g-MAH content of 3% by weight, The foams were produced under the conditions of 160/170/160/150/140/140 applying 5% by weight of EMC. The wool fibers were dried in a 70 vacuum oven for at least 24 hours before use.

[Comparative Example 1]

The same procedure as in Example 1 was repeated except that 15 wt% of sheep fiber was added in the preparation of the composite and the foam, and PE-g-MAH having a degree of MAH graft of 40% was used.

[Comparative Example 2]

The preparation of the composite and the foam was carried out in the same manner as in Example 1, except that 17 wt% of sheep fiber was added, and PE-g-MAH having a degree of MAH graft of 40% was used.

[Comparative Example 3]

The procedure of Example 1 was repeated except that PE-g-MAH having a degree of MAH graft of 40% was used in the preparation of the composite and the foam.

[Comparative Example 4]

The procedure of Example 1 was repeated except that PE-g-MAH having a degree of MAH graft of 50% was used in the preparation of the composite and the foam.

[Comparative Example 5]

The procedure of Example 1 was repeated except that PE-g-MAH was not used in the preparation of the composite and the foam.

<Specific gravity measurement>

The specific gravity of the foam was measured using a water displacement method and the average value of five samples was measured.

&Lt; Contact angle measurement &

The HDPE-yam fiber composite is made into a 25 mm x 25 mm x 1 mm plate and the angle is measured after 3 seconds after dropping water using a phoenix contact angle meter from SEO.

<Measurement of tensile properties>

The tensile properties of the HDPE-yam fiber composite were measured using a universal tester (Hounsfield, H10KS, UK) with a 1 mm-thick tensile specimen at a tension rate of 5 mm / min.

The specimens were also prepared using a 170 hot press.

<Foamed cell structure>

The foam cell structure of HDPE-wool fiber-EMC foam was measured using a scanning electron microscope (SEM, Tescan Mira3) by gold sputter coating of the cut surface of the sample.

division Contact angle () Modulus of elasticity (Mpa) Tensile Strength (Mpa) importance Graft of PE-g-MAH (%) Example 1 72.7 18.1 25.5 0.78 44% Comparative Example 1 65.9 17.2 19.5 0.64 40% Comparative Example 2 61.3 15.3 17.7 0.81 40% Comparative Example 3 64.3 16.2 15.1 0.90 40% Comparative Example 4 62.1 16.5 13.4 0.91 - Comparative Example 5 72.1 16.2 20.2 0.80 50%

As shown in FIGS. 2, 3, 4 and Table 1, the tensile properties, specific gravity and specific gravity of the HDPE-yam fiber composite and the EMC applied in excess of 15 wt% Considering the foam cell structure, the application of PE-g-MAH is essential, and the degree of MAH grafting of PE-g-MAH is an important factor.

That is, in the case of Comparative Examples 1 to 3 where the degree of grafting was 40% or less, the contact angle was measured to be 61.3 to 65.9, so that a sufficient compatibilizing effect was not obtained as compared with Example 1 which was 72.7 and the grafting degree was 50% , The elastic modulus of Comparative Example 4 was 16.5, the tensile strength was 13.4, and the tensile strength was reduced by about 47% compared with Example 1. In view of this, mechanical property deterioration was caused by PE-g-MAH will be.

The decrease in the tensile properties of the HDPE-yam fiber composites and the specific gravity of the foams applied with the compatibilizer improves the interfacial adhesion between the HDPE and the yam fiber, and the yam fiber is melted and kneaded like HDPE, The higher the degree of MAH grafting of PE-g-MAH, the higher the degree of improvement in interfacial adhesion properties of HDPE-yam fiber composite with high sheep fiber content. The degree of MAH grafting of PE-g-MAH can be confirmed from FIG. 1 and [Table 1].

In addition, the contact angle of [Table 1] is larger for the HDPE-yam fiber composite in which the compatibilizer having a high degree of MAH graft is used, because the degree of improvement of the interfacial adhesion property is better.

As a result, it was confirmed that the mechanical properties were increased by applying the compatibilizer having a high degree of MAH grafting to the HDPE-yam fiber composite through the above-mentioned experiment, and the increase of foamed cells of EMC-applied foam was proved.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the appended claims.

Claims (8)

Composite materials comprising high density polyethylene (HDPE) and natural fibers, polyethylen-g-maleic anhydride (PE-g-MAH) and thermally expandable microcapsules (EMC)
The compatibilizer, polyethylen-g-maleic anhydride, has a graft rate of greater than 40% but less than 50%. The method according to claim 1,
Wherein the natural fibers are at least one selected from the group consisting of hemp fibers, sisal fibers and bamboo fiber fibers. delete The method according to claim 1,
Wherein the natural fibers are from 15 to 50% by weight, based on the total weight of the foam composition. The method according to claim 1,
The thermally expandable microcapsules (EMC) are present in an amount of 1 to 10% by weight, based on the total weight of the foam composition,
Wherein the foam composition has a specific gravity of 0.8 or less. delete An automotive part material comprising the foam composition according to any one of claims 1, 2, 4 and 5. 1) reaction extruding polyethylen-g-maleic anhydride (PE-g-MAH) using a twin-screw extruder;
2) A composite material and heat-expandable microcapsules (EMC) containing polyethylen-g-maleic anhydride (PE-g-MAH), high density polyethylene (HDPE) , &Lt; / RTI &gt;
Wherein the compatibilizer, polyethylen-g-maleic anhydride, has a graft rate of greater than 40% but less than 50%.

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