METHOD AND APPARATUS FOR PRODUCING A LAMINATE

Abstract: A method and an arrangement for producing a laminate structure which is comprised of alternating smooth and corrugated sheets which form a corrugated or cellular structure. The structure is used, for instance, in the manufacture of so-called exchange contactors for the exchange of heat and moisture, among others. The starting material used is, for instance, a paper web comprised of formable material, such as fiber glass, cellulose or the like. The starting material is saturated or impregnated with a concentrated waterglass solution with the aid of impregnating means (14, 16), and is then dried by drying means (18, 26) to a dry solids content of 45-65 % with regard to the waterglass. The paper web (P1) is then corrugated with the aid of corrugating means (30) and is combined with a further, smooth paper web (P2) that has been saturated with waterglass and subsequently dried. The laminate structure formed by the two paper webs (P1, P2) is then dried (46) to a dry solids content of about 60-95 % with regard to the waterglass.

Description: Method and apparatus for producing a laminate The present invention relates to a method of manufac- turing a laminated structure comprised of alternate smooth and corrugated board which forms a corrugated laminate for the subsequent manufacture of contact bod¬ ies, hereinafter referred to as contactors, for use in the manufacture of heat-exchangers and moisture -exchangers and corresponding devices. Contactors, for instance contactors which are intended for the exchange of moisture or heat, or both, are typi¬ cally comprised of thin layers of forraable material, such as paper webs of glass fibers, cellulose or the like, which can be formed into a laminate structure, by combin¬ ing smooth and corrugated paper-web board or sheets and mutually bonding the sheets so as to form a structure that exhibits a plurality of open, through-passing pas- sageways or cells. In known methods for producing such contactors, for instance in the form of a rotor, the corrugated and smooth paper webs are normally joined together with the aid of an organic adhesive, which is also applied to the laminate when coiling the laminate to form a rotor-shaped contactor, or when binding smooth laminate sheets to a cube-shaped contactor. The contactor is then impregnated with a waterglass solution, so as to form a gel which is then subsequently treated converted into to a solid substance on the contact T, thereby imparting moisture- transferring and heat-t: nsferring properties to the contactor. The contactor is normally impregnated with waterglass, by immersing the cube-shaped or rotor-like contactor in a waterglass solution. This method is enσum- bered with several drawbacks, however. For instance, it is desirable to impregnate the contactor with the great¬ est possible amount of waterglass, in order to impart good moisture-transference and heat-transference proper- ties to the contactor. However, as a result of the large quantities of waterglass absorbed by the submerged con¬ tactor, the contactor shrinks in size by 15 to 20% It is necessary to take this shrinkage into account when manu¬ facturing the contactor blank or preform. Another draw- back with this known method is that it is often necessary to burn-off the organic adhesive, in order to provide "a contactor which will not burn readily. However, those laminate surfaces which were earlier covered by the adhesive will not have been impregnated with waterglass during the impregnation process and will therefore be devoid of waterglass when the adhesive is burned-off. -knottier drawback of the known method, in which the fin¬ ished contactor is submersed in a waterglass solution, is that the narrow contactor passageways readily become blocked, meaning that the waterglass solution used must be relatively thin-bodied. Still another drawback is that the waterglass solution is relatively unevenly distribut¬ ed throughout the contactor. US-Patent Specification 3,419,937 teaches a method of manufacturing filters by impregnating a cellulose paper with a slurry that contains petalite and a small amount of talc mixed in an epoxy solution. The paper is brought to a desired form and then heat-treated. This method, which relates to the manufacture of porous filter material, cannot be applied in the manufacture of an exchange contactor of the kind to which the present invention relates, since the introduction of those sub- stances included in the slurry used with the known method would impair the properties of the contactor. The main object of the present invention is to provide a method and an arrangement which will eliminate the draw¬ backs of the known manufacturing processes. Another object is to provide a method and an arrangement for manufacturing contactors, with which the extent to which the material shrinks or contracts during the gel¬ ling process is reduced. A further object of the invention is to provide a method and an arrangement for manufacturing contactors in which the impregnating substances, such as waterglass, are distributed evenly throughout the contactor, in a con¬ trolled manner, during the manufacturing process. These and other objects of the invention are achieved with an inventive method and an inventive arrangement having the characteristic features set forth in the following method and apparatus claims. The invention will now be described in more detail with reference to an exemplifying embodiment thereof illu- strated in the accompanying drawing, the single figure of which illustrates schematically a plant for producing a laminate structure comprised of alternating smooth and corrugated sheets and capable of being used in the manu¬ facture of contactor bodies. The illustrated plant includes a roll 10 consisting of a paper-web of formable, or shapeable material, such as fiber glass, cellulose or like material. The web is taken from the roll 10 in the direction of the arrow shown, and is passed over a guide roller 12 and down into a vessel 14 which contains concentrated waterglass solution. The web P. is guided down beneath the surface of the water- glass solution in the vessel 14 with the aid of a guide roller 16, which is immersed in the solution. As the web P 1 passes through the vessel 14, the web becomes saturat¬ ed with concentrated waterglass solution. As will be understood, the waterglass solution, which may consist of a sodium-silicate solution which is later converted to silicate gel for impregnating the paper, may be brushed or otherwise applied to the paper web in quantities such as to saturate said web. After having been saturated with the concentrated waterglass solution, the paper web P 1 is moved upwards, as seen in the drawing, to a drying sta¬ tion 18, which includes a plurality of drying sections 20, in the illustrated case four drying sections which may either operate with hot-air units or infrared units. The paper web P. is then advanced, via guide rollers 22 and 24, to a further drying station 26 which includes drying sections 20 of the aforedeεcribed kind and in which the paper web . is further dried. When the web leaves the drying station 26, the waterglass will have a dry solids content of about 45-65%, preferably 45-55%. The paper web P. is then passed, via a guide roller 28, to a corrugating roller 30 on which the web P^ is corru¬ gated so as to form a large number of shallow corruga¬ tions in the paper web. In order to obtain the aforedescribed laminate having alternate smooth and corrugated layers, a second paper web P, is taken from a paper roll 32 and passed, via a guide roller 34, into a vessel 36 which contains con- centrated waterglass solution and into which the paper web P 2 is immersed, via a roller 38. The paper web P, is therewith saturated with concentrated waterglass solution and is passed from the vessel 36 to a drying station 40 which includes a plurality of drying sections 20 of the same kind as those earlier described with reference to drying of the paper web P.. The paper web P 2 is dried in the drying station 40, preferably from that side of the web which will later face away from the paper web P. when the two webs P 2 , P 2 are brought together to form a lami¬ nate. Although the drying process affects the whole of the paper web, that side which faces towards the web P.. in the laminating process will have a higher moisture content than the outwardly facing side of said web. After leaving the drying station 40, the paper web P 2 is combined with the corrugated paper web P., via a guide roller 42, and the combined paper webs forming the lami¬ nate L are pressed together between the guide roller 42 and the roller 44, thereby bonding the webs together with the waterglass functioning as a bonding agent. After bonding together the two paper webs, the resultant lami¬ nate L is passed through a further drying station 46, which includes a plurality of drying sections 20 of the aforedescribed kind. The laminate is dried in the drying station 46 to a dry solids content of about 60-95% with regards to waterglass. As will be understood from the aforegoing, the paper in the laminate L is impregnated initially with large guan- tities of waterglass sufficient to impart the desired proper" es to the contactor subsequently manufactured from t„. laminate. Because the paper web P-, which is subsequently corrugated, is saturated with waterglass and then dried to a dry solids content of about 45-65%, preferably 45-55%, and is thus in a wet, plastic state, it is possible to use smaller corrugation heights and therewith obtain a uniform, homogenous corrugated surface structure without risk of blocking the subsequent pas¬ sageways. Since waterglass is the only adhesive used to bond the layers together, there is no need to burn-off the rotor and the laminate will therewith be impregnated over the whole of its surface, including the bonding locations. When practicing the inventive method, the silica gel formed in the aforesaid after- treatment is less fluffy and thus produces less dust when the contactor is used. As will be understood, the invention is not limited to the illustrated and described method and arrangement, and that modifications and variations can be made within the scope of the following claims.

Claims: Claims 1. A method of producing a laminate structure comprised of alternating smooth and corrugated sheets and forming a corrugated structure for the manufacture of so-called exchange contactors for the exchange of heat and moisture among others, c h a r a c t e r i z e d by saturating a starting material, such as a first paper web of formable material, for instance, fiber glass, cellulose or the like, with a concentrated waterglass solution; drying the paper web to a dry solids content of about 45-65% with respect to the waterglass; corrugating said paper web; saturating a second paper web with concentrated water¬ glass solution and drying said web; combining the second paper web with the first paper web so as to form a lami¬ nate stru ture; and drying the laminate structure to a dry solids content of about 60-95% with regard to the waterglass. 2. A method according to Claim 1, c h a r a c ¬ t e r i z e d by drying the second paper web preferably from one side thereof; and by combining the second paper web with the first paper web in a manner such that the wetter side of the second paper web is brought into contact with the corrugated, first paper web. 3. A method according to Claim l or 2, c h a r a c ¬ t e r i z e d by passing the paper webs through a water¬ glass solution such as to saturate said webs with said solution. 4. A method according to any one of Claims 1-3, c h a r a c t e r i z e d by drying the paper webs with 8 the aid of hot air or infrared heat radiation. 5. A method according to any one of Claims 1-4, c h a r a c t e r i z e d by drying the first paper web to a dry solids content of about 45-55% with regard to the waterglass. 6. An arrangement for carrying out the method according to any one of Claims 1-5 for the manufacture of a lami- nate structure comprised of alternating smooth and corru¬ gated sheets, c h a r a c t e r i z e d by impregnating means (14, 16) for impregnating a first paper web (P.) with concentrated waterglass solution; drying means (18, 26) for drying said impregnated paper web (P..); corrugat- ing means (30) for corrugating the first paper web (P 1 ); means (36, 38) for saturating a second paper web (P 2 ) with concentrated waterglass solution; drying means (40) for drying the second paper web (P 2 ); and web combining means (42, 44) for combining the first paper web and the second paper web to form a laminate structure (L) , and drying means (46) for drying the laminate structure (L) thus produced. 7. An arrangement according to Claim 6, σ h a r a c - t e r i z e d in that the drying means (18, 26, 40, 46) include hot-air heaters or heaters which function with infrared heat radiation, said heaters either being used individually or in combination. 8. An arrangement according to Claim 6 or 7, c h a r a c t e r i z e d in that the drying means (40) for the second paper web (P 2 ) are so arranged that the side of the paper web which is to be brought into contact 9 with the first paper web will be wetter. 9. An arrangement according to any one of Claims 6-8, c h a r a c t e r i z e d in that the means for impreg¬ nating or saturating the paper webs (P., P 2 ) include guide means (16, 38) for guiding the paper webs down into vessel (14, 36) containing waterglass solution.

Inventors: SVENSSON RONNY, VANGBO HAAKAN, SVENSSON, RONNY, VANGBO, HAAKAN
Applicants: MUNTERS AB CARL, AB CARL MUNTERS
Application year: 1992
Main classification: B32B31
IPC codes: B31F1, B32B3, B32B38