Stock material or miscellaneous articles – Composite – Of polyester
Patent
1992-01-29
1992-09-01
Griffin, Ronald W.
Stock material or miscellaneous articles
Composite
Of polyester
8190, 4273899, 427394, D06M 13322, C08J 506
Patent
active
051437910
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Cellulose fibres have since long ago been used as reinforcement in laminates, compression moulding compounds and the like in combination with resins based on formaldehyde, for example phenol-formaldehyde-, melamine-formaldehyde- and urea-formaldehyde resins. It has not been possible to combine other resins such as polyester- and epoxi resins with cellulose fibres so that a reinforcement effect has been acheived. However cellulose, wood powder etc. have been used as filling materials for making the material cheaper.
Cellulose fibres have very good inherent tensile properties. The E-module for cellulose I is about 140 GPa, which makes the material to one of the strongest. For cellulose II the theoretic module is 90 GPa. Regenerated cellulose fibres are manufactured with a module of 48 GPa, while cotton has a module of 5-11 GPa. As a comparisson it can be mentioned that E-glass fibres have an E-module of 70 GPa. With regard to the high density of glass fibres, i.e. if the specific modules are compared, cellulose fibres are well comparable with glass fibres. Besides the break elongation is higher for cellulose and the price is lower.
The main volume of composite materials are today manufactured with glass fibres as reinforcement. The glass fibre per se is not compatible (i.e. is not wetted) with polyester resins but is always treated in order to improve wetting and preferably provide chemical (covalent) bond between fibre and matrix. Such a bond gives optimal mechanical properties to the composite material. It is common that the glass fibres are treated with a vinyl silane which gives a surface with projecting vinyl groups. These can copolymerize with the polyester resin and accordingly give a convalent bond between the fibre and the matrix. A corresponding treatment of cellulose fibres is however not practiced.
In the Swedish patent No. 6809101-6 (publication No. 372.533) is described a method of manufacturing a cellulose polymer with dihalogene-s-triazinyl groups bonded thereto. At the method cellulose having free hydroxyl groups, i.e. has been reacted with an alkaline acting agent, is treated with a cyanuric halide while maintaining an acid pH. With this method large amounts of reagent is required, in the stated examples the same amount by weight of reagent as cellulose. The yield is in spite of this poor. This depends on the fact that the reagent, which is added dissolved in acetone, has reacted with the hydroxyl groups in the water solution, which thus competes with the hydroxyl groups of the cellulose. The method is therefore not economically justifiable on a large scale.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method for treatment of cellulose fibres, so that these are given a hydrophobic surface and for example are wetted by certain resins in order to be combined with these for manufacture of composite materials, in which the resin makes the matrix of the composite and the fibres make the reinforcement. The method shall be simple to perform and give a high yield.
This has been attained by the fact the fibres in the first step are treated with a solution, dispersion or melt containing a reagent having the general formula ##STR1## where B-X is a hydroxyl compound or an amine, at which 1) X is at least one alkyl-, aryl- or aryl alkyl chain, or which e.g. originates from an acrylic group, methacrylic group, allyl compound etc., and then in a second step are treated with an alkaline acting agent and that at the same time or in connection herewith a heat treatment is performed.
The invention also concerns composite materials manufactured by the treated cellulose fibres in combination with resins, especially such where the matrix and the fibres are combined with covalent bonds.
DESCRIPTION OF THE INVENTION
The reagents which have been used can be considered to comprise three parts A-B-X, where A is the group which is bonded to the cellulose, B is the compatibilizing part and X can be the part reacting with the matrix. The reagents are bas
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patent: 2632744 (1953-03-01), Howald
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patent: 3104935 (1963-09-01), Moyse
patent: 4572859 (1986-02-01), Fushiki et al.
Flodin Per
Zadorecki Pawel
Griffin Ronald W.
Polyrand AB and Polycell Kompositer
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