MITSUBISHI Develops Automotive Interior Materials Using Bamboo Fibers

The MITSUBISHI automobile industry announced on the "seventeenth polymer material forum" (sponsored by the macromolecule society and held in Hiroshima international conference hall from November 27, 2008 to 28) (speech number 2PA02), and successfully developed a composite resin material made of bamboo fiber as reinforcement material, and the goal is to be used for automotive interior parts.

It is the first time to use bamboo fiber as an automotive component.

The use of plant materials is designed to reduce carbon dioxide emissions.

At present, the company is discussing the related issues of mass production, "we hope to reduce the cost to about 1.5 times of the existing materials".

The procedure for fibrosis of bamboo is as follows: first, we divide the bamboo into four pieces and remove the slub, and then use special equipment (not open) to crush and obtain fibers.

Previously, bamboo fibrosis was carried out by steam explosion (decomposition of fibers by steam heating), but because of acetic acid, formic acid, acetaldehyde and VOC (volatile organic compounds), it could not be used for automobile purposes.

This method does not have such a problem.

The company produces bamboo fibers by synthesizing (1) PBS (polybutadiene styrene) resin and (2) polybutene resin.

These two resins mostly use plant materials.

(1) PBS resin is made from succinic acid fermented by sugar and starch, and directly dehydrated from 1,4-Butanediol in petroleum.

Hybrid Bamboo Fibers and PBS fibers are made of hybrid fibers, which are formed by hot pressing technology (Fig. 1).

Plant content (weight ratio of plant material) is about 83%.

As the physical characteristics of the composite material, mechanical properties have reached the level of real vehicle.

The composite material has been used to provide the rear panel interior trim of electric vehicles "iMiEV" since February 2008.

The problem is that the water is easily decomposed and the water decomposition inhibitor must be added. However, the inhibitor has high price and low heat resistance (the bending temperature of the load is 109 degrees Celsius), so the components are limited.

At present, the feasibility of the "iMiEV" mass production vehicle is being discussed.

(2) polybutene is a resin produced by polyol composition and polyimide resin. Most of the polyols are replaced by castor oil polyol and coconut oil glycerin.

The hybrid fiber was made from bamboo fiber by adding adhesive resin. The hybrid fiber was filled with metal mold, and the polyol component and polyimide ester component were injected by reaction injection molding machine (RIM).

The content of plants is about 60%.

In terms of the physical properties of the composites, the load bending temperature is 193 degrees, and all the index values are higher.

However, as a vehicle material, compared with the general PP (polypropylene) resin, there are still some problems such as slow production speed and high manufacturing cost, so it will be further improved in the future.

It is mainly used for car door decorative board substrate, seat rear baffle and roof material.

About carbon dioxide emission reduction effect, the carbon dioxide emissions from the whole life cycle (from raw material to waste) were calculated. Bamboo fiber PBS resin composite material was about 51% of the original petroleum PP resin, and bamboo fiber plant carbamate resin composite material was about 28%, and the reduction effect was remarkable.

Yang Jing: editor in charge