Method of producing wood fiber type composite material product h

Details Method of producing wood fiber type composite material product h Method of producing wood fiber type composite material product h

1998-09-23

2000-05-23

Theisen, Mary Lynn

Plastic and nonmetallic article shaping or treating: processes

Forming articles by uniting randomly associated particles

With liberating or forming of particles

264109, 264122, 524 13, 525 543, 525 64, B29C 4700, B29C 4500, C27N 328, C08L 9702

Patent

active

060662786

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a method for producing a composite material mainly composing of a wood cellulose filler and olefin series plastic. In particular, the present invention relates to a method for producing a composite material exhibiting high rigidity and high heat deformation temperature by adding a rigidity improving (or imparting) agent to a mixture of the wood cellulose filler and the olefin series plastic.


TECHNICAL BACKGROUND

A composite material composing of a mixture of a wood cellulose filler, which is produced as a filler by finely crushing a material such as wood, hardboard, pulp or hemp, and a granular olefin series plastic material of polyethylene or polypropylene (PP) is molded by extrusion molding or injection molding, and such a composite material product is widely used as a variety of parts, boards and sheets.
Physical properties, such as flexual strength, flexual modulus, impact strength and heat deformation temperature, of such a composite material can be improved by appropriately selecting a material, a particle size and a mixing amount of the wood cellulose filler, and thus, such a composite material is also used for a variety of interior parts of a car.
However, in such a composite material composing of a mixture of a wood cellulose filler and olefin series plastic, it is known that the rigidity is decreased as the water content thereof is increased, as shown in Table 1. This is because water is excessively produced from the wood cellulose filler by heat produced when the olefin series plastic material contained in the mixture is melted and kneaded and such excessive water reduces the adhesive property between the wood cellulose filler and the olefin series plastic material.


TABLE 1 ______________________________________ Physical Properties of Extrusion Molded Sheet of Wood Cellulose Flour (W.C.F)/Plastic Composite Material ______________________________________ Compositions: Standard composition* Water content of W.C.F (%): 3-5 7-8 Strength: Tensile strength (kg/mm.sup.2) 2.71 2.49 Flexual strength (kg/mm.sup.2) 4.61 4.12 Flexual modulus (kg/mm.sup.2) 443 394 ______________________________________ *Standard composition = PP:W.C.F:Recycled composite material = 2:2:1
In order not to reduce the adhesive property therebetween and in order to improve the physical properties described above, it is necessary to dry in advance the wood cellulose filler to 3-4% water content so as to keep the water content below 5% when mixing. If a recycled composite material, which includes the same components as a composite material to be produced, is used to produce the composite material, the recycled composite material is crushed in a predetermined size and the crushed recycled composite material is used as one component of the composite material. In this case, it is necessary to dry a wood cellulose filler materials included in the recycled composite material into 5% water content.
The olefin series plastic is commonly used as a matrix of the composite material. However, the olefin series plastic is chemically inert (i.e. not polarizable) and is less affinity. Thus, an essentially good adhesive property between the matrix and the wood cellulose filler can not be achieved. That is, the improvement of the physical properties of the molded product of such a composite material is limited. In order to improve the adhesive property of the olefin series plastic which is chemically inert and is less affinity, in practice, polypropylene modified by maleic anhydride having a low degree of modification by maleic anhydride and a large molecular weight is used as an additive (a rigidity improving agent) for improving the adhesive property therebetween.
By adding such a rigidity improving agent (2-7%) to a mixture of olefin series plastic and a filler consisting of glassfiber, talc, calcium carbonate and the like, a composite material having improved rigidity and heat-resisting property can be obtained, and such a rigidity impr

REFERENCES:
patent: 5574094 (1996-11-01), Malucelli et al.
XP-002092287, May, 24, 1994, Derwent Patent Abstract.
XP-002092288, Jan. 15, 1992, Derwent Patent Abstract.
XP-002092289, Mar. 22, 1994, Derwent Patent Abstract.
XP-002092290, Jan. 10, 1992, Derwent Patent Abstract.
European Patent Application No. 97941223.6, Supplementary European Search Report dated Feb. 4, 1999.

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