Board product and method for making the same

Abstract

A method of forming a coated boxboard product is provided. A boxboard product is formed without being processed by a Yankee dryer, and further comprises a plurality of fiber plies, including outermost plies forming the top and back sides and comprised of bleached chemical pulp, and medial plies disposed between the outermost plies and comprised of at least one of groundwood, pressure groundwood, chemithermo-mechanical pulp, recycled pulp, and broke. The boxboard product is precalendered with a surface conditioning device and then coated such that the coated boxboard product has a density of between about 500 kg/m 3 and about 1000 kg/m 3 , and a basis weight of between about 150 g/m 2 and about 500 g/m 2 , and the top side of the coated boxboard product has a PPS-s10 roughness of between about 0.8 μm and about 3.0 μm and a Hunter gloss of between about 30% and about 80%.

1 . A coated boxboard product, which has two or more fiber plies and outside plies consisting of bleached chemical pulp and middle plies of mechanical pulp and/or broke or recycled fiber, and which board has a surface density of 150-500 g/m 2 , said board having a top side and a backing side, wherein the boxboard product is manufactured without using a Yankee cylinder, the production of said boxboard product involving prior to coating the use of one or more surface conditioning devices functioning as a precalender and comprising: 
 a fixed support element ( 14 ),    a flexible jacket ( 12 ) fitted around the fixed support element ( 14 ), such that a board web ( 80 ) travels between the jacket ( 12 ) and a counter-roll ( 22 ),    a load element ( 18 ,  20 ) provided in connection with the support element ( 14 ), such that the flexible jacket ( 12 ) is applied by the load element ( 18 ,  20 ) against the heatable counter-roll ( 22 ), the board web ( 80 ) present between the jacket ( 12 ) and the counter-roll ( 22 ) becoming calendered, and at least one end wall ( 24 ,  26 ) mounted at the end of the flexible jacket ( 12 ) in such a way that the flexible jacket is attached to the end wall ( 24 ,  26 ) and the jacket is rotated along with the end walls by means of a drive mechanism, characterized in that the middle ply material consists of one or more materials in the following group:    groundwood (GW), pressure groundwood (PGW), chemithermo-mechanical pulp (CTMP), recycled pulp and broke;    that the coated product has surface properties on the top side of the board as follows: 
 PPS-s10 roughness (ISO 8791-4) 0,8-3,0 μm  
 Hunter gloss (ISO/DIS8254) 30-80%,  
 and that the product has a density (SCAN-P7:75) within the range of 500-1000 kg/m 3 .  
   
   
   
       2 . A product as set forth in  claim 1 , characterized in that the top side is coated one or more times.  
   
   
       3 . A product as set forth in  claim 1  or  2 , characterized in that the backing side is uncoated.  
   
   
       4 . A product as set forth in  claim 1  for  2 , characterized in that the backing side is coated at least once.  
   
   
       5 . A product as set forth in any of the preceding claims, characterized in that the basis weight is within the range of 180-400 g/m 2 .  
   
   
       6 . A product as set forth in any of claims  1 - 5 , characterized in that the basis weight is within the range of 180-350 g/m 2 .  
   
   
       7 . A product as set forth in any of claims  1 - 6 , characterized in that the top side has a Bendtsen roughness (SCAN-P21:67) within the range of 0-500 ml/min.  
   
   
       8 . A product as set forth in any of claims  1 - 6 , characterized in that the top side has a Bendtsen roughness (SCAN-P21:67) within the range of 0-150 ml/min.  
   
   
       9 . A product as set forth in any of claims  1 - 8 , characterized in that the top side has a PPS-s10 roughness (ISO 87911-4) within the range of 1,0-2,5 μm.  
   
   
       10 . A product as set forth in any of claims  1 - 9 , characterized in that the top side has a Hunter gloss (ISO/DIS 8254) within the range of 35-65%.  
   
   
       11 . A product as set forth in any of the preceding claims, characterized in that it has a density (SCAN-P7:75) within the range of 600-850 kg/m 3 .  
   
   
       12 . A product as set forth in any of claims  1 - 12 , characterized in that the product calendering has also involved the use of a single- or multi-nip machine and/or soft calender.  
   
   
       13 . A product as set forth in any of claims  1 - 12 , characterized in that its precalendering has involved the use of board surface wetting.  
   
   
       14 . A product as set forth in any of claims  1 - 12 , characterized in that its precalendering has not involved the use of board surface wetting.  
   
   
       15 . A method for making a coated boxboard product, said boxboard product having two or more fiber plies and having its outside plies consisting of bleached chemical pulp and middle plies of mechanical pulp and/or broke or recycled fiber, and said board having a basis weight of 150-500 g/m 2 , the boxboard product being manufactured without using a Yankee cylinder, in which method a web to be coated is prior to coating introduced into a surface conditioning device, comprising: 
 a fixed support element ( 14 ),    a flexible jacket ( 12 ) fitted around the fixed support element ( 14 ), such that a board web ( 80 ) travels between the jacket ( 12 ) and a counter-roll ( 22 ), a load element ( 18 ,  20 ) provided in connection with the support element ( 14 ), such that the flexible jacket ( 12 ) is applied by the load element ( 18 ,  20 ) against the heatable counter-roll ( 22 ), the board web ( 80 ) present between the jacket ( 12 ) and the counter-roll ( 22 ) becoming calendered, and at least one end wall of the calendering device mounted on the end of the flexible jacket in such a way that the flexible jacket ( 12 ) is attached to the end wall ( 24 ,  26 ) and the jacket is rotated along with the end wall ( 24 ,  26 ) by means of a drive mechanism and the web is precalendered with said surface conditioning device, characterized in that the middle ply material consists of one or more materials in the following group:    groundwood (GW), pressure groundwood (PGW), chemithermo-mechanical pulp (CTMP), recycled pulp and broke;    that the coated product has surface properties on the top side of the board as follows: 
 PPS-s10 roughness (ISO 8791-4) 0,8-3,0 μm  
 Hunter gloss (ISO/DIS8254) 30-80%,  
 and that the product has a density (SCAN-P7:75) within the range of 500-1000 kg/m 3 .  
   
   
   
       16 . A method as set forth in  claim 15 , characterized in that the precalendering involves the use of surface wetting.