WO2009139508A1

WO2009139508A1 - Composites of kenaf micro fiber with polypropylene or polylactic acid

Info

Publication number: WO2009139508A1
Application number: PCT/JP2009/059479
Authority: WO
Inventors: Subiyakto; Bambang Subiyanto; Euis Hermiati; Dede Heri Yuli Yanto; Fitria; Kurnia Wiji Prasetyo; Ismail Budiman; Ismadi; Wingky Kurniawan; Takashi Inoh
Original assignee: Indonesian Institute Of Sciences (Lipi); Toyota Jidosha Kabushiki Kaisha
Priority date: 2008-05-16
Filing date: 2009-05-18
Publication date: 2009-11-19
Also published as: JP2011523430A; CN102099404A

Abstract

The invention relates to a composite material which comprises admixture of kenaf (Hibiscus cannabinus) bast micro fibers and a polymer of polypropylene and/or polylactic acid, wherein the micro fibers are contained in an amount of 20 to 80 % by weight. According to the present invention, composite material for automotive components that has high strength and environmentally friendly composed of kenaf micro fiber and polypropylene or polylactic acid matrices can be achieved.

Description

COMPOSITES OF KENAF MICRO FIBER WITH POLYPROPYLENE OR POLYLACTIC ACID

Technical Field

The present invention relates to a composite material and a method for manufacturing the same for application of automotive components. In more particular, the present invention relates to a high strength and environmentally friendly composite material composed of kenaf bast micro fiber and polypropylene (PP) or polylactic acid (PLA) .

Background Art Improvement of the quality of environment through clean development program is a priority program in most countries in the world. In the automotive industries for example, utilization of materials that poluted the environment such as fiber glass, carbon and aramid fibers is gradually being reduced and substitute with natural fibers to make "green car". As an example, European Union End of Life of Vehicles (ELV) program requires that in the year of 2015 all new cars should have 95% recycleable materials (Marsh 2003) . Therefore composites reinforced with natural fibers will play important role and might be a revolutioner material of this century (Marsh 2003) . Some advantages using natural fibers compared to sintetic fibers are renewable, biodegradable, recyclable, non toxic to environment and health, lighter density, better mechanical properties, non abrasive to toolls, and lower price (Zimmermann et al . 2004, Oksman et al . 2003, Wambua et al. 2003, Mohanty et al. 2002, Leao et al . 1998) . Utilization of natural fibers reduce car weight up to 40%, lower energy to produce natural fiber (4 GJ/ton) compare to glass fiber (30 GJ/ton) , and production of glass fiber release toxic gases such as CO₂, NO_x, SO_x and dust (Marsh 2003) . While many advantages are obtained of using natural fibers for composite, some drawbacks are realized. Natural fibers are hydrophilic in character, when it combined with polymer matrix that are hydrophobic then they have a lower compatibility. Natural fibers are also required low processing temperature to about 200⁰C to prevent fiber degradation (Nakagaito et al. 2005) . To overcome the drawbacks, addition of coupling agent in the matrix and improve processing methods are applied.

One of natural fibers that has a good potential is kenaf {Hibiscus cannabinus) . Kenaf is an annual plant that can reach 4 to 5 m high and 4 to 5 cm in stem diameter, it grows rapidly. Kenaf can be planted through the year and grow at any elevations, the harvesting time is about 120 days. On dry weight basis the bast fiber content on the stem ranges from 21% to 36%. Dimension of kenaf bast fiber is 2 to 3 mm in length and 15 to 25 μ m in width. The chemical content of kenaf bast fiber is: cellulose (44-62%), hemicellulose (14-20%), lignin (6-9%) and pectin (4-5%) . While the density of kenaf bast fiber is 1.47 g/cm³, tensile strength is 479-1600 MPa, and Young's modulus is 18.2 GPa. As raw material for industry, kenaf has good potential because the yield is about 1.5 to 5 ton dry fiber per ha. Kenaf grows as fast as 7-8 cm per day that means it has a fast photosynthetic rate so can absorb a large carbon dioxide; therefore it can be planted for reducing global warming.

Fiber size is very important factor in producing composites for automotive components. In order to increase the strength of composites, smaller fiber size such as micro fibril cellulose (MFC) is required. United States Patent 20060147695 describes a kenaf fiber reinforced composites containing kenaf fiber of 100 μm to 20 mm and polymer matrix of polylactic acid for products of electrical and electronic equipment.

United States Patent 5973035 describes an invention that features a composite including a resin, such as a thermoplastic resin, and at least about 2% by weight, more preferably at least about 5% by weight, texturized cellulosic or lignocellulosic fiber. The invention also features a composite that includes polyethylene and at least about 50% by weight texturized cellulosic or lignocellulosic fiber. The composites have flexural strengths of at least about 3, 000 psi, or tensile strengths of at least about 3,000 psi. The process to produce the composite includes shearing cellulosic or lignocellulosic fiber to form texturized cellulosic or lignocellulosic fiber, then combining the texturized fiber with a resin. A preferred method -includes shearing the fiber with a rotary knife cutter. Shearing caused the internal fibers are substantially exposed. After shearing, the "texturized cellulosic or lignocellulosic fiber" at least about 50%, more preferably at least about 70%, of these fibers have a length/diameter (L/D) ratio of at least 5, more preferably at least 25, or at least 50.

United States Patent 4559376 describes a method to produce composites based on cellulose or lignocellulosic materials and plastics according to which method the cellulose or lignocellulose material is subjected to a pre- hydrolytic or other chemically degrading treatment prior to or during the compounding or processing step whereby a comminution and improved dispersion of the cellulose or lignocellulose material in the plastic phase is achieved. The thermoplastic composite contains up to 40% by weight of the pre-hydrolytic cellulose or lignocellulose incorporated therein. A masterbatch concentrate is produced which contains up to 70% by weight of the pre-hydrolytic cellulose or lignocellulose incorporated therein.

United States Patent 6939903 describes a process for preparing a composite material which comprises: a) sizing a natural fiber with a reactive organosilane; b) mixing the sized natural fiber with a polyolefin resin; and c) adding a functionalized polyolefin coupling agent to the mixture of the sized natural fiber and the polyolefin resin to provide said composite material. The objective of this invention is to obtain a composite for automotive components that has high strength and environmentally friendly composed of kenaf micro fiber and polypropylene or polylactic acid matrices. The objective can be achieved through products and methods describes in the claims.

Summary of Invention

The invention relates to a composite product for automotive components that contains a mixture of kenaf micro fiber and polymer of polypropylene (PP) and/or polylactic acid (PLA) .

Kenaf fiber was firstly processed into pulp, and then fibrillated using stone grinder. Kenaf fiber has the diameter size of 10 to 50 μ m and mixed with polymer, preferably.

Composite of kenaf micro fiber and polypropylene (PP) was made by mixing dry pulp with granular polypropylene (PP) in a mixer (Labo plastomill) at, for example, 170 to 190 ⁰C, 50 to 70 rpm for 10 to 30 minutes. The amount of kenaf micro fiber was 40 to 80% of by weight (composite weight) . During the mixing, maleic anhydride polypropylene

(MAPP) was preferably added as coupling agent at the amount of, for example, 3 to 12.5% of the weight of composite. The mixture of materials was removed from the Labo plastomill and put into plates with teflon sheets put on the plates to make a mat form and then hot pressed. Hot pressing was conducted at temperature of, for example, 170 to 190 ⁰C, pressure of, for example, 1 MPa for 30 to 60 seconds. After hot pressed, the plate was immediately put in a cold press at pressure of, for example, 1 MPa for 3 to 7 minutes. Then the board was taken from the plates.

Composite board of kenaf micro fiber and polylactic acid (PLA) was done as follow. Firstly PLA was dissolved in dichloromethane and stirred at room temperature. Wet pulp was put into the dissolved PLA and stirred until homogenous. During the mixing, triacetin as plasticizer was preferably added as plasticizer at the amount of, for example, 3 to 9% of the weight of composite. The amount of kenaf micro fiber was 30 to 60% of composite weight, preferably . The mixture was dried in an oven at, for example, 60 to 105 ⁰C for 12 to 36 hours. Dried mixture was processed further in a mixer (Labo plastomill) at temperature of, for example, 160 to 180 ⁰C, 50 to 70 rpm for 10 to 30 minutes. The mixture was removed and put into plates with teflon sheets put on the plates to make a mat form and then hot pressed. Hot pressing was conducted at temperature of, for example, 170 to 190 ⁰C, pressure of 1 MPa for 30 to 60 seconds. After hot pressed, the plate was immediately put in a cold press at pressure of, for example, 1 MPa for 3 to 7 minutes. Then the board was taken from the plates.

Brief Description of Drawings

This invention was described in detail using the following figures:

Figure 1 describes flow chart of preparation process of composite of kenaf micro fiber with polypropylene (PP) according to this invention. Figure 2 describes flow chart of preparation process of composite of kenaf micro fiber with polylactic acid (PLA) according to this invention.

Description of Embodiments

Kenaf fiber was processed firstly into pulp, and then fibrillated using stone grinder to have the size of 10 to 50μm, preferably, and mixed with polymer.

In accordance with Figure 1, composite of kenaf micro fiber and polypropylene (PP) was made by mixing dry pulp with granular polypropylene (PP) in a mixer (Labo plastomill) at 170 to 190 ⁰C, 50 to 70 rpm for 10 to 30 minutes. The amount of kenaf micro fiber was 40, 50, 60, 70, and 80% of composite weight. During the mixing maleic anhydride polypropylene (MAPP) was added as coupling agent at the amount of 3, 5, 7.5, 10, and 12.5% of the weight of composite. The mixture of materials was removed from the Labo plastomill and put into plates with teflon sheets put on the plates to make a mat form and then hot pressed. Hot pressing was conducted at temperature of 170 to 190 ⁰C, pressure of 1 MPa for 30 to 60 seconds. After hot pressed, the plate was immediately put in a cold press at pressure of 1 MPa for 3 to 7 minutes. Then the board was taken from the plates. In accordance with Figure 2, composite board of kenaf micro fiber and polylactic acid (PLA) was done as follow. Firstly PLA was dissolved in dichloromethane and stirred at room temperature. Wet pulp and triacetin as plasticizer were put into the dissolved PLA and stirred until homogenous. The amount of kenaf micro fiber was 30, 40, 50, and 60% of composite weight. The amount of triacetin added was 3, 5, 7, and 9% of the weight of composite. The mixture was dried in an oven at 60 to 105 ⁰C for 12 to 36 hours. Dried mixture was processed further in a mixer (Labo plastomill) at temperature of 160 to 180 ⁰C, 50 to 70 rpm for 10 to 30 minutes. The mixture was removed and put into plates with teflon sheets put on the plates to make a mat form and then hot pressed. Hot pressing was conducted at temperature of 170 to 190 ⁰C, pressure of 1 MPa for 30 to 60 seconds. After hot pressed, the plate was immediately put in a cold press at pressure of 1 MPa for 3 to 7 minutes. Then the board was taken from the plates.

The obtained board was shaped into test piece having 50x150 mm. The both ends of the test piece were freely supported so as to have 100 mm span length. Applying a load of 50 mm/min to the center of the span length, and an amount of deflection was measured. Then, load-deflection curve for each test piece can be obtained. The value of the load in wihch the test piece was broken is defined as the maximum bending load (at 50mm width) . The Bending elasticity gradient was defined as the bending load at 1 cm deflection caluculated from the amount of strain in linear region of the load-deflection curve at beginnig of loading and bending load. Test results were shown in tables 1 to 4.

Table 1.

Value of bending elasticity gradient and maximum load of composite kenaf micro fiber / PP (50/50) at several percentages of MAPP.

Table 2.

Values of bending elasticity gradient and maximum load of composite kenaf micro fiber - PP at several ratios of kenaf micro fiber/PP with 5% MAPP.

Table 3.

Values of bending elasticity gradient and maximum load of composite kenaf micro fiber/ PLA (50/50) at several percentages of triacetin.

Table 4.

Values of bending elasticity gradient and maximum load of composite kenaf micro fiber - PLA at several ratios of kenaf micro fiber/PLA.

Based on the above results, the preferred composition of kenaf micro fiber and PP was that having ratio of 50 : 50 with addition of 5% MAPP. While the preferred composition kenaf micro fiber and PLA was that having ratio of 50 with addition of 7% triacetin.

Claims

1. A composite material which comprises admixture of kenaf {Hibiscus cannabinus) bast micro fibers and a polymer of polypropylene and/or polylactic acid, wherein the micro fibers are contained in an amount of 20 to 80 % by weight.

2. The composite material according to claim 1, wherein the micro fibers have diameter of 10 to 50 μm.

3. The composite material according to claim 1, wherein, in case that the polymer comprises polypropylene, the admixture further comprises Maleic Anhydride Polypropylene (MAPP) .

4. The composite material according to claim 3, wherein the amount of Maleic Anhydride Polypropylene (MAPP) is 3 to 12.5% by weight.

5. The composite material according to claim 1, wherein, in case that the polymer comprises polylactic acid, the admixture further comprises triacetin.

6. The composite material according to claim 5, wherein the amount of triacetin is 3 to 9% by weight.

7. The composite material according to claim 1, wherein the density is in the range of 0.8 to 1.4 g/cm³.

8. A process for producing a composite material comprising kenaf (Hibiscus cannabinus) bast micro fibers and a polymer of polypropylene and/or polylactic acid which comprises steps of: a) mixing the bast micro fibers and the polymer, wherein the micro fibers are mixed in an amount of 20 to 80 % by weight; b) conducting hot pressing of the product resulted in step a) ; and c) conducting cold pressing of the product resulted in step b) ;

9. The process according to claim 8, wherein the micro fibers have diameter of 10 to 50 μm.

10. The process according to claim 8, wherein, in case that the polymer comprises polypropylene, Maleic Anhydride Polypropylene (MAPP) is further mixed with the bast micro fibers and the polymer.

11. The process according to claim 10, wherein the amount of Maleic Anhydride Polypropylene (MAPP) is 3 to 12.5% by weight .

12. The process according to claim 8, wherein, in case that the polymer comprises polylactic acid, the admixture further comprises triacetin is further mixed with the bast micro fibers and the polymer.

13. The process according to claim 12, wherein the amount of triacetin is 3 to 9% by weight.