Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1997-07-17
2001-03-20
Yao, Sam Chuan (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S177000, C156S181000, C156S244150, C264S113000, C264S115000, C264S121000, C427S180000, C428S074000
Reexamination Certificate
active
06203646
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of producing a mineral fibre element comprising a mineral fibre base layer having a surface coating in the form of a fibrous netting formed of a thermoplastic polymer material, wherein such a surface coating is provided on at east a part of the surface of the base layer.
Mineral fibre material is used, among other things, for thermal and acoustic insulation in a n umber of connections.
In order to increase the tactility of the mineral fibre material used during the handling and mounting thereof it may be coated with a surface layer, e.g. consisting of a non-woven sheet material of polymer fibres.
Furthermore, such a surface coating serves to reduce or eliminate the release of fibre wads or single fibres from the mineral fibre material to the surroundings before, during or after mounting.
Furthermore, a surface coating of the above-mentioned type imparts a considerably increased tensile strength to the mineral fibre element.
It is known to produce mineral fibre elements of the type mentioned in the introductory part by adhering a pre-manufactured, non-woven web material consisting of polymer fibres to the surface of a web-formed mineral fibre material by using a resin, such as phenol formaldehyde resin, as an adhesive, and by subsequently cutting the coated mineral fibre web so as to form individual mineral fibre matts.
Non-woven polymer fibre materials can be produced from thermoplastic polymers which, among things, are characteristic in being adhesive in melted state. In the production of non-woven fibre materials the adhesive effect can be used to bond the individual fibres together to form a coherent layer.
However, the prior art method suffers from several drawbacks.
In order to impart sufficient strength to the non-woven material so as to enable it to resist strains during the handling thereof and in particular during the application of the material onto the uneven surface of the mineral fibre material, the material used should have a surface weight of at least about 20 g/m
2
.
However, it is not necessary to use a surface coating having a surface weight of such a magnitude in order to obtain a functional coating, and hence the prior art method involves a certain waste of material.
Furthermore, the resin used for adhering the non-woven material implies an increase in the thermal value of the surface coated mineral fibre element, which is undesirable for fire safety reasons.
In addition, mineral fibre elements produced by the prior art method are relatively costly, which is partly due to the fact that non-woven polymer fibre materials are costly and partly that the method comprises at least two relatively difficult technical process steps, viz. 1) an even application of the adhesive onto the surface of the base layer and 2) mounting and pressing of the coating onto the surface.
Finally, it is strenuous and difficult to form a surface coating covering the entire surface of the base layer, i.e., both the upper side and lower side of the base layer and its edge surfaces, by use of the prior art method.
The object of the present invention is to provide a method of the type mentioned in the introductory part which is simpler than the prior art method and by which a mineral fibre element having improved properties can be obtained.
SUMMARY OF THE INVENTION
The method according to the invention is characterized in that the surface coating is formed directly on the surface of the base layer and that the surface coating is formed by heating a thermoplastic polymer material so as to melt it and distributing the polymer melt obtained in the form of fibres and/or filaments on the surface of the base layer and cooling it to form a solid layer.
The invention is based on the discovery that, by forming the polymer layer directly on the surface of the mineral fibre material, the adhesive effect possessed by thermoplastic polymer materials in a melted or partly melted state can be utilized to obtain a highly effective adhesion between the mineral fibre layer and the surface coating and at the same time the use of a further binder can be avoided, thereby allowing the thermal value of the mineral fibre element to be reduced.
Furthermore, the invention is based on the discovery that the non-woven material used in the prior art method, in particular as a result of the strength requirements demanded for effecting the application of the material onto a mineral fibre base layer, has properties which are undesired, unnecessary and unexpedient as far as its function as a surface coating is concerned, and that the direct formation of the surface coating on the mineral fibre material provides a possibility of obtaining a surface coating, properties are exclusively determined on the basis of the desired functional considerations.
Thus, the method according to the invention provides a possibility of forming a surface coating with an arbitrary surface weight, and as a result it is possible to obtain a material saving as compared to the prior art method.
Furthermore, by using the present method it is possible to form a surface coating consisting of fibres having a smaller thickness than that of the fibres of the non-woven materials used in the prior art method, and thus a material saving can be obtained as well as a possibility of increasing the number of fibres per area unit and hence the filtration capacity of the surface coating.
Finally, the invention is based on the discovery that a surface coated mineral fibre element can be produced more economically and easily by forming the surface coating directly on the mineral fibre material than by adhering a pre-manufactured non-woven material onto the mineral fibre material, as the former method does not require a separate process equipment for producing a non-woven material, and hence the process steps associated therewith can be avoided, and as the former method only requires one process step, whereas the latter method requires at least two process steps.
In addition, the surface coating formed by the present method is cut more easily than the prior art surface coating, which to a large extent facilitates the cutting of the mineral fibre elements, which ordinarily is necessary in connection with the mounting thereof.
As used in the present invention the term “mineral fibres” includes rock fibres, glass fibres and slag fibres.
As used in the present invention the term “thermoplastic polymer material” means any natural or synthetic thermoplastic polymer or polymer blend. A thermoplastic material is characterized in that it is solid or partially solid at room temperature or at temperature of use, that it melts when heated and that it solidifies or resumes a solid or partially solid form when cooled.
The term “thermoplastic polymer material” also includes such materials which are ordinarily referred to as “thermoplastic hot melt adhesives” or “hot melt adhesives” or simply “hot melts”.
By way of examples thermoplastic polymer materials are polymers of ethylenically unsaturated monomers, such as polyethylene, polypropylene, polybutylenes, polystyrenes, poly(&agr;-methyl styrene), polyvinyl chloride, polyvinyl acetate, polymethyl methacrylate, polyethyl acrylate, polyacrylonitrile, etc; copolymers of ethylenically unsaturated monomers, such as copolymers of ethylene and propylene, ethylene and styrene, polyvinyl acetate, styrene and maleic anhydride, styrene and methyl methacrylate, styrene and ethyl acrylate, styrene and acrylonitrile, methyl methacrylate and ethyl acrylate etc; polymers and copolymers of conjugated dienes, such as polybutadiene, polyisoprene and polychloroprene and polymers of bi-polyfunctional monomers, such as polyesters, polycarbonates, polyamides and polyepoxides.
Particularly preferred thermoplastic polymer materials are polyesters, polyamides, polypropylene and polyvinyl acetate.
By using the method according to the invention it is possible, as mentioned above, to produce mineral fibre elements having a surface coating of an arbitrary thickness.
However, in order to o
Garn Claus Bugge
Gundberg Martin Vendelbo
Ostrolenk Faber Gerb & Soffen, LLP
Rockwool International A/S
Yao Sam Chuan
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