Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-03-10
2002-04-23
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S288000, C156S289000, C156S307500, C156S307700, C156S322000, C156S324000
Reexamination Certificate
active
06375777
ABSTRACT:
The present invention relates to a process for the production of a thermosetting, preferably decorative laminate.
Products with a surface layer of thermosetting resin are frequently used today. They are used mostly where the demands for abrasion resistance are high but also where resistance against different chemicals and humidity is requested. Flooring materials, skirtings, work tops, table tops, cupboards, wall panels and facades can be mentioned as examples on such products. The thermosetting laminate often consists of a number of base sheets with a closest to the surface placed decor sheet of paper and on top of the decor sheet usually one or more protective so-called overlay sheets of &agr;-cellulose.
Thermosetting laminates are produced by laminating together at an increased pressure paper sheets or paper webs impregnated with a thermosetting resin. In respect of paper sheets this is made in a static press and in respect of paper webs in continuous presses. Continuous laminate presses have been known for a long time and they are manufactured for instance by the companies Kvaerner and Hymmen. The presses are furnished with two endless belts. The laminate is pressed between these belts.
For a long time there has been a great need of being able to produce a decorative thermosetting laminate in a rational a cost-effective way without decreasing the quality demands. One such method would be to produce two or more laminates at the same time in continuous presses. However, this has been considered to be impossible.
According to the present invention it has been possible to meet the above need whereby the cost efficiency at the production of thermosetting laminates has been considerably improved. Thus, the invention relates to a process for the production of a thermosetting preferably decorative laminate. The laminate is made of a number of paper sheets preferably in the form of continuous webs impregnated with a thermosetting resin and then dried. The dry paper webs are fed between the press belts of a continuous double belt press and laminated together in the press at an increased pressure and an increased temperature. The invention is characterised in that the continuous paper webs are divided into at least two groups each consisting of at least two sheets of which at least one is impregnated with a thermosetting resin, the sheets consisting of
a) one or more decorative paper webs preferably impregnated with a thermosetting resin and/or
b) one or more overlay paper webs of &agr;-cellulose preferably impregnated with a thermosetting resin and/or
c) one or more bottom colour paper webs preferably impregnated with a thermosetting resin and/or
d) one or more base paper webs preferably impregnated with a thermosetting resin and one or more separation sheets which are placed between the groups of paper webs. The separation sheets are used for separating the groups of paper webs from each other after a finished pressing whereby at least two thermosetting laminates are obtained.
According to one embodiment of the invention the separation sheet for each group consists of an unimpregnated paper web, a paper web impregnated with a thermosetting resin on one side or a paper web coated with a thermosetting resin on one side. The unimpregnated or uncoated side is turned away from the laminate with the possibly coated or impregnated side turned inwards towards the laminate.
Alternatively the separation sheet for each group can consist of an impregnated paper web, an unimpregnated paper web, a paper web impregnated with a thermosetting resin on a first side or a paper web coated with a thermosetting resin on a first side while the other side of the web is coated or impregnated with a passive material. The first side is turned towards the respective group. The passive material then suitably consists of alginate, a metal such as aluminium or plastics such as electron cured acrylate, polyphenyl oxide, polyimide or polyvinylidene fluoride.
According to a second embodiment of the invention the separation consists of one or more separation webs.
A first and a second group of paper webs each comprising a decor paper web are used according to one embodiment of the invention. The decor paper web of the first group is directed with the decor towards the upper press belt with possible intermediate overlay paper webs and possible further underlying decor paper webs, bottom colour paper webs and base paper webs. The decor paper web of the second group is directed with the decor towards the lower press belt with possible intermediate overlay paper webs and possible further decor paper webs placed above, bottom colour paper webs and base paper webs. One or more separation webs are placed between the first group and the second group. Further groups of paper webs with intermediate separation webs can be fed between the press belts together with the first and the second group.
A first structure web is suitably placed between the upper press belt and the first group of paper webs. A second structure web is suitably placed between the lower press belt and the lower group of paper webs. The surface structure of the two structure webs is directed towards the respective paper webs, whereby the two laminates produced at the pressing are provided with a surface structure from the structure webs.
Alternatively the press belts of the continuous press can be furnished with a surface structure. Then the structure webs are eliminated.
A surface structure is above all used for increasing the realism of the decor of the decor paper web. The decor paper web can be provided with a decor or pattern as desired. Usual patterns tend to imitate different kinds of wood or mineral such as marble or granite. The decor can also be a wholly fancy pattern. The decor of the structure web gives a negative image thereof in the laminate at the pressing. The structure suitable reproduces characteristic features of the pattern the decor of the laminate represents. The structure can here be made rough to simulate for example a rough-hewn stone or be glossy with small pits and micro cracks placed at random to simulate polished marble. In order to simulate the surface structure of wood the laminate surface is furnished with thin elongated recesses to look like pores. These recesses must be turned in the growth direction of the simulated tree which is shown by the pattern of the graining to give a realistic result. Therefore, the graining and the simulated pores are often placed in the longitudinal direction of the laminate.
According to an alternative embodiment of the invention a first and a second group of paper webs each includes a decor paper web. The decor paper web of the first group is turned with the decor away from the upper press belt down towards an imagined middle plane with possible underlying overlay paper webs and possible further decor paper webs placed above, bottom colour paper webs and base paper webs. The decor paper web of the second group is then directed with the decor away from the lower press belt up towards an imagined middle plane with possible overlay paper webs placed above and possible further underlaying decor paper webs, bottom colour paper webs and base paper webs. One or more separation webs are placed between the first group and the second group. Further groups of paper webs with intermediate separation webs can be fed between the press belts together with the first and the second group.
The separation web can here preferably consist of
a) a metal such as aluminium steel and copper or
b) a plastic foil for example of polyamide, polyoxymethylene, polycarbonate, polyfluorethene, polyvinylidene fluoride, polyphenyl oxide, polyether sulphone, polyimide, polysiloxane or
c) paper preferably having a surface coating for example consisting of electron cured acrylate, polyphenyl oxide, polyimide, polyvinylidene fluoride, aluminium or the like.
The plastic foils according to c) above can suitably be reinforced with fiber reinforcement to get an increased endurance. Such reinforcement can for instance consist of glass f
Larsson Håkan
Sjölin Hans
Aftergut Jeff H.
Perstorp AB
Stevens Davis Miller & Mosher L.L.P.
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