Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1991-10-01
1993-08-10
Lesmes, George F.
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
57229, 428246, 428252, 428257, 428258, 428259, 428260, 428272, 428273, 428284, 428285, 428286, 428289, 428290, 428298, 428302, 428373, 428375, 428377, 428408, 428902, 4289088, B32B 1704, D03D 1500, D02G 338
Patent
active
052347524
DESCRIPTION:
BRIEF SUMMARY
This invention relates to wear-resistant laminated articles, such as bearings, and rotor blades for pumps and compressors.
Well-known articles of this kind are made by heating an assembly of superimposed layers of cloth made of asbestos yarn and impregnated with a thermosetting resin.
The present invention is concerned with avoiding the use of asbestos.
It is already known (see for example GB-A-2 121 844) to make wear-resistant laminated articles using, instead of resin- impregnated asbestos cloth, heat-resistant aramid fibres, that is to say fibres of poly(aromatic amide), or glass fibres, made with an organic binder into flexible sheet material by a paper-making process, the sheet being then impregnated with resin. However, to obtain articles capable of sustained operation above 175.degree. C., and in particular at temperatures up to 200.degree., there has to be used a proportion of aramid fibre which makes the product too expensive. If glass fibre is used instead of aramid fibre, the article is extremely abrasive.
According to the present invention there is provided a wear-resistant laminated article made by heating an assembly of superimposed layers of fabric impregnated with thermosetting resin, in which the fabric is made of non-asbestos yarn comprising a core of glass fibre with a surface of aramid fibre and a relatively porous fibre, the aramid fibre forming not more than 40% by weight of said yarn.
Fabric made of such non-asbestos yarn is commercially available as thermal insulation and packing, the relatively porous fibre therein being viscose. The function of the viscose fibre in the practice of the present invention is to assist impregnation with thermosetting resin of the fabric of glass core fibre/aramid surface fibre. The fabric is preferably woven, but may be of knitted construction.
The aramid fibre employed can be all of the para-form, such as that sold under the trade mark KEVLAR, but up to half of the aramid can if desired by contributed by meta-form such as poly(m-phenylene-iso-phthalamide).
A preferred composition of the yarn is the fabric should have a weight per unit area in the range 550-900 grams/m.sup.2.
A friction modifier such as graphite, polytetrafluorethylene or molybdenum disulphide at levels from 2 to 20% by dry weight of the thermosetting resin may if desired be included to improve the wear-resistance of the product.
Suitable thermosetting resins are phenolic resins, such as phenol-formaldehyde resins derived from phenol itself or a hydrocarbon-substituted phenol.
For certain applications such as very heavy duty compressor blades, the novel wear-resistant articles described above may lack sufficient stiffness.
To remedy this, carbon fibres may be incorporated into the laminate. This may be accomplished by interleaving the fabric layers with layers of a carbon fibre resin pre-preg material, prior to lamination into an article. The carbon fibre may be in the form of a woven cloth or a non-woven felt, although the former is preferred. The resin is preferably the same as the resin used to impregnate the fabric, a phenolic resin being particularly preferred. The carbon fibre content may be in the range of from 5 to 30% by weight, more preferably in the range 10 to 25% by weight.
The phenolic resin may contain from 2-10% by weight of an epoxy resin material, together with a hardener for the latter, in order to promote adhesion to the carbon fibres. An epoxy resin content of about 5% by weight is particularly preferred.
The carbon fibres may also be blended into the fabric as an integral component thereof. For example, a carbon fibre weft may be used in making the fabric. In some circumstances, this latter approach may be preferable to incorporation immediately prior to lamination because it results in a more uniform distribution of the carbon fibre reinforcement.
The invention is further illustrated by the following Example.
EXAMPLE ONE
A plain weave cloth of nominal thickness 2 mm, weight per unit area 620 grams/m.sup.2, and a construction of 80 ends per dm and 36 picks per
REFERENCES:
patent: 4446191 (1984-05-01), Miyadera et al.
patent: 4548678 (1985-10-01), Laflin et al.
patent: 4927698 (1990-05-01), Jaco et al.
patent: 4967548 (1990-11-01), Fangaet et al.
Colley Geoffrey
Kerwin John E.
Laflin Philip
Newton David R.
Lesmes George F.
Tenmat Limited
Withers James D.
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