CA1120301A - Method for improving of paper pulp stock manufactured mechanically from wood - Google Patents
Method for improving of paper pulp stock manufactured mechanically from woodInfo
- Publication number
- CA1120301A CA1120301A CA000337933A CA337933A CA1120301A CA 1120301 A CA1120301 A CA 1120301A CA 000337933 A CA000337933 A CA 000337933A CA 337933 A CA337933 A CA 337933A CA 1120301 A CA1120301 A CA 1120301A
- Authority
- CA
- Canada
- Prior art keywords
- pulp
- filler
- defibrating
- filler material
- wood
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
- D21B1/14—Disintegrating in mills
- D21B1/16—Disintegrating in mills in the presence of chemical agents
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
- D21B1/14—Disintegrating in mills
- D21B1/18—Disintegrating in mills in magazine-type machines
- D21B1/24—Disintegrating in mills in magazine-type machines of the pocket type
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Paper (AREA)
- Soft Magnetic Materials (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE :
A method for improving the properties of a paper pulp stock manufactured by comminuting wood material mechanically and for increasing the retention grade of the filler material in the pulp with the purpose of improving without a chemical reaction the optical and printing properties of the paper made from the said pulp which pulp is made by defibrating wood, characterized in that filler materials are added to and mixed with the fibrous material in the defiberizing machine, during the defibration process in such a process phase, when the ligning or equivalent bound to the fibers, as a result of the high temperature generated during the defibration process is soft plasticized and sticky and is able in enhanced manner to make the filler material particles adhere to the surface of the fibers.
A method for improving the properties of a paper pulp stock manufactured by comminuting wood material mechanically and for increasing the retention grade of the filler material in the pulp with the purpose of improving without a chemical reaction the optical and printing properties of the paper made from the said pulp which pulp is made by defibrating wood, characterized in that filler materials are added to and mixed with the fibrous material in the defiberizing machine, during the defibration process in such a process phase, when the ligning or equivalent bound to the fibers, as a result of the high temperature generated during the defibration process is soft plasticized and sticky and is able in enhanced manner to make the filler material particles adhere to the surface of the fibers.
Description
3C`~
The present invention relates to a method (or proce-dure) for improvinc3 the properties of paper pulp stock made by mechanically comminuting wood material and for increasing the retention grade of its filler content to the end of improving, wlthout any chcmical reaction, the optlcal and printing character-istics of the paper made from said pulp, this pulp being made by defibrating wood, preferably in log form.
The manufacturing of paper pulp stock from wood, or defibration of the wood raw material into fibres appropriate for paper making can be accomplished in a pulp cooking process by chemical means, or by subjecting the wood material to a mechanic-al defibration process.
There are two main types of mechanical wood defibrating methods, as set forth in the earlier Finnish patent N54818 filed by the same applicant. The oldest of them is the grinding pro-cess, wherein wet logs having a suitable length are urged against the coarse surfaced mantle of a cylindrical grinding stone which is being rotated. Water is also conducted in appropriate quantity onto the grinding surface, its presence being indispensable, as dry wood yrinding would produce worthless wood flour. As a result of the process, virtually all of the wood material run through the process is converted into a fibre/water slurry, splinters and slivers excluded. Fibre material of this type is used for raw material of newsprint, for instance.
In a more recent mechanical pulp manufacturing method, the wood raw materia~ is introduced into the process in the form of chipped wood, that is of wet chips, these being de-fibrated, for instance, between two dis~-type grinding elements rotating against each other and which present an appropriate surface structure. In this process, too, the output is a paper pulp slurry, which is suitable, after screening, to be used for paper making.
,,1, - 1 - a~
~lZ~30'1 Wooc3 is well knowll to co~ltain lignitl between 20 and 30 per cellt, ligl~in ~)eing a high-molecular aromatic substance.
~,ignill is a substal~ce resembling glue and binds the wood fibres together. The greater part oE the lignin is dissolved during the cooking, while it remains on the fibres through the rnec}lanical deibration process.
It is characteristics of both mentioned mechanical pulp mallulacturil)g mcthods oL prior art:-- that all the corlstituents o wood, that is '.he cellulose fibres and the lignin bonding them mutually, are present in the pulp fibre stock obtained, and -that an appreciable amount of heat is generated in the defibra-tion process, as mechanical energy is converted into heat, causing thc pulE) stock temE>erature to rise to a level sufficient to render the lignin soft and sticky.
These two circumstances are significant with a view to improving the properties of paper pulp stock made of wood by mechanical means, as taught by the present invention. In the first place, the paper's optical properties are concerned, on which an in1uence is exerted, as known in itself in prior art, by admixing to the stock a suitable chemically inert filler, usually of mineral origin, such as talc, china clay, etc.
The use of mineral fillers in papers is practiced, above all, for the reason that these additives improve the paper's printing properties. There are two different ways in which the filler may be added: by admixture to the paper stock or ~y coating the paper web with iller material. ~rhe present inven-tion reads on a procedure of the first type. When added to the pulp, the ~iller is added in suspension form to the pulp stock 3n slurry prior to its entering the paper machine. To accomplish this, the filler, made up to a 30 to 40 per cent aqueous suspen-sion, is introduced intothe mixing chest preceding the high 112~3~1 consistency stock chest. Talc, for instance, may be added as an aqueous suspensioll on the intake side of the so-called head-box pump.
The quantities used wher, the filler is added to the paper stock vary Erom 2 to 40 per cent~ caLculated on the weight of the completed paper, depending on paper grade. Commonest are filler contents between 5 and 20 per cent. The commonest fillers used are talc, clay (kaolin), chalk, and equivalent. The use of high quality fillers appreciably increasing the opacity of the paper above all, such as titanium oxide and zinc sulphide, has recently increased. It may be observed in catalogue fashion that the use of fillers is intended to improve the opacity and brightness of the paper, to add to its ink recep-tivity, and to imptove the smoothness and finishing capacity.
A problem invariably encountered when using fillers is their mostly unsatisfactory retention to the fibres. It is certainly possible to admix filler material to the pulp stock slurry to produce a homogeneous ayueous suspension of fibres and filler particles. But when this suspension is conducted 2t) onto the paper machine wire, where the water is drawn off and the fibres combine to form a continuous web, what happens is that a considerable proportion of the fillers escape with the water, and the part staying in the web tends to concentrate in one or the other superficial part of the web, giving rise to so-called one-sidedness. It is possible to improve the retention and to eliminate the drawbacks mentioned, in part at least, by using certain additives. As a rule, however, such are compara-tively expensive, and otller disadvantagcs may be associated with them.
The aim of tl-e present invention is to provide a procedure for improving the filler retention without using any special retention aids. This procedure can be contemplated in particular 3~
in the case of paper pulp stock mechanically made from wood, where the fibres ha~e retained their inherent lignin. As stated, lignin at a high enough temperature is soft and sticky, and the partly lignin-covered fibres are then able with ease to bind on their surface a greater amount of filler particles than usual.
However, the said temperature at which lignin displays this property important in view of filler retention only prevails at or immediately after the defibrating step. Therefore, in order to obtain the desired result, the filler must be conducted into contiguity with the fibres at this particular stage.
Although in the following lignin is mentioned with par-ticular emphasis as the constituent of wood or equivalent which undergoes plastic conversion under a temperature increase from 100 to 170 Centigrade, for instance, it is to be noted that certain paper stocks have other constituents, hemicellulose for instance, which become plastic in like manner as lignin, from the viewpoint of the present invention. Therefore, such constituents fall within the scope of the invention as well.
For instance, hardwood pulps and paper stock made of bagasse contain remarhable amounts of hemicellulose, which behaves in a manner substantially similar to the behaviour of lignin, with a view to the invention in hand.
The procedures of prior art for improving the filler retention of paper pulp include for example, a system wherein the improvement of retention is attributable to increased fibril-lation of the cellulose fibres, whereby the filler particles adhere mechanically to the numerous fibrils on the fibres.
In connection with mechanical pulp producing processes, the procedure disclosed in the U.S. Patent No. 3,388,037 is known in the art, wherein additives are introduced into the refiner grinder, the purpose being to achieve a bleaching effect. However, a chemical reaction between the fibre material and the additives is concerned in this case.
~12~30~
It should be underlined in particular that the aim of the present invention is to improve the retention by physical means, in other words making use of the ability of th~ lignin in the fibres to bind, like glue, filler particles on the fibre surf~cc at a givcn tcmperaturc.
~ ccording to the present invention, there is provided a method ~or improving the properties of a paper pulp stock manufactured by comminuting wood material mechanically and for increasing the retention grade of the filler material in the pulp with the purpose of improving without a chemical reaction the optical and printing properties of the paper made from the said pulp which pulp is made by defibrating wood,charac-terized in that filler materials are added to and mixed with the fibrous material in the defiberizing machine, during the defibration process in such a process phase, when the lignin or equivalent bound to the fibers, as a result of the high temperature generated during the defibration process is soft plasticized and sticky and is able in enhanced manner to make the filler material particles adhere to the surface of the fibers.
In the following, the invention is described in detail with reference being made to an embodiment example, presented in the figures Gf the attached drawing, to which it is not in any way confined.
The figure presents a more detailed embodiment example of the process of the invention.
The grinding machine shown in the figure comprises a chamber 1 for the loys 2 to be ground, a grinding stone 3 rotating in the direction indicated by arrow, and below the stone, a pulp pit 4. Means known in themselves in prior art, such as hydraulically plunger (not depicted) for instance, are employed to urge the logs 2 against the surface of the stone. The water indispensable in the grinding process is - '112~3~
directed on the surface of the stone by means of the jet pipe 5. The pulp produced in the process collects as a fibre/water suspension 9 in the pit - 5a ~
l~ZV301 4 ullder the stone and rulls ~ver the over10w weir 8 into the cllannel 10, wl~el~ce the stock is [orwarded by the pump 11 to a screening apparatus (not depicted) for the removal of splillters etc., and f~rther to the papcr rnakiny process. The grindiny stone and stock pit are enclosed in a hermetically sealed chamber 12, where it is possible if required to maintain an over-pressure e.g. by the aid of compressed air introduced through the line 14, provided with valve 13. The stock pit 4 comprises an extension part 16 with mixer 15 and which has been provided with an incomplete partition 17, this partition guiding the contin~ous stock flow entering the pit ~o flow through the extension part of the pit towards the overflow. The apparatus also comprises a jet pipe 6, through which filler suspension is conducted onto the surface of the grinding stone in the form of a suspension of approximately 30 to 40 per cent. Another jet pipe 7 has been provided to supply filler in among the pulp on the surface of the stone. The introduction of filler material may be through one of the two jet pipes only, or using both, depending on circumstances. To the pit 4 is connected a steam pipe 19 with valve 13 for the heating of the pulp 9 in case additional heat is required in the process. The task of the mixer 15 is, on one hand, to maintain the pulp flow through thc extension part 16 and, on the other hand, to provide for eEficient admixture of the filler to the stock.
The power brought to the shaft of the grinding stone 3 is converted to heat in the grinding process, and the temperature of the fibre pulp produced may in the grinding zone rise to a remarkable level (100 to 130 Centigrade~, similarly as in the process wherein a disk refiner is used. E~ereby the lignin or equivalent in the fibres softens and becomes sticky, It is however necessary to dilute the fibre stock obtained by grinding, to a consistency such that it can be pumped. The ;)3V~
ad(lillg o~ dilution water, whic}l may be accomplished through the jet pipe (5a), rapidly lowers the temperature of the pulp sus-pension far below 100 Centigrade.
If it is desired to utilize the capacity of lignin-containing fibres to bind filler material on thei~ surface, the addition or filler must take place in connection with or imrne~iately after the grinding event. The Eiller suspension may be conducted onto the bare surface of the grinding stone at a point before the grinding zone. But if this should inter-fere with the grinding event, it is also possible to perEorm -the filler addition immediately after the grinding zone, onto the pulp-covered surface of the grinding stone.
In order to ensure adhesion of the filler particles, endeavours should be taken to prolong the dwelling time of the pulp in the stone pit, this being done by increasing the capacity of the pit with the aid of an extension part. The same end, i.e., positive fixation of the filler, is served by the mixer placed within the extension part and by the possibility of heating the pulp with the aid o~ steam.
It is well known that the production of high grade ground-wood implies that the logs subjected to the process are wet and that enoug water is present in the grinding process proper.
The large heat quantity produced in the process and the temper-ature rise past 100 Centigrade may result in fast evaporation of water and drying out of the material in the grinding zone.
It is possible with a view to preventing this, to carry out the grinding process in a pressure-tight volume in which an over-pressure is maintained with the aid of compressed air, or in-stance. The over-pressure may also be produced by the aid of the steam used to heat the pulp in the pit under the grinding stone.
Such pulp stock brands are also among the possible ~lZ~)301 applications of the present invention i21 which heretofore no fillers have been used, but in which their use may now be commenced on account of the advantages afforded by the inven-tion. These applications irlclude newsprints particularly when endeavours are to reduce the base weight of newsprint, which is a general aspiration nowadays. This now becomes possible, especially owing to the improved opacity of the paper.
The invention is in no way narrowly confined to the embodiment examples described above by way of example alone, of which various details may vary within the inventive idea laid down in the claims stated below.
The present invention relates to a method (or proce-dure) for improvinc3 the properties of paper pulp stock made by mechanically comminuting wood material and for increasing the retention grade of its filler content to the end of improving, wlthout any chcmical reaction, the optlcal and printing character-istics of the paper made from said pulp, this pulp being made by defibrating wood, preferably in log form.
The manufacturing of paper pulp stock from wood, or defibration of the wood raw material into fibres appropriate for paper making can be accomplished in a pulp cooking process by chemical means, or by subjecting the wood material to a mechanic-al defibration process.
There are two main types of mechanical wood defibrating methods, as set forth in the earlier Finnish patent N54818 filed by the same applicant. The oldest of them is the grinding pro-cess, wherein wet logs having a suitable length are urged against the coarse surfaced mantle of a cylindrical grinding stone which is being rotated. Water is also conducted in appropriate quantity onto the grinding surface, its presence being indispensable, as dry wood yrinding would produce worthless wood flour. As a result of the process, virtually all of the wood material run through the process is converted into a fibre/water slurry, splinters and slivers excluded. Fibre material of this type is used for raw material of newsprint, for instance.
In a more recent mechanical pulp manufacturing method, the wood raw materia~ is introduced into the process in the form of chipped wood, that is of wet chips, these being de-fibrated, for instance, between two dis~-type grinding elements rotating against each other and which present an appropriate surface structure. In this process, too, the output is a paper pulp slurry, which is suitable, after screening, to be used for paper making.
,,1, - 1 - a~
~lZ~30'1 Wooc3 is well knowll to co~ltain lignitl between 20 and 30 per cellt, ligl~in ~)eing a high-molecular aromatic substance.
~,ignill is a substal~ce resembling glue and binds the wood fibres together. The greater part oE the lignin is dissolved during the cooking, while it remains on the fibres through the rnec}lanical deibration process.
It is characteristics of both mentioned mechanical pulp mallulacturil)g mcthods oL prior art:-- that all the corlstituents o wood, that is '.he cellulose fibres and the lignin bonding them mutually, are present in the pulp fibre stock obtained, and -that an appreciable amount of heat is generated in the defibra-tion process, as mechanical energy is converted into heat, causing thc pulE) stock temE>erature to rise to a level sufficient to render the lignin soft and sticky.
These two circumstances are significant with a view to improving the properties of paper pulp stock made of wood by mechanical means, as taught by the present invention. In the first place, the paper's optical properties are concerned, on which an in1uence is exerted, as known in itself in prior art, by admixing to the stock a suitable chemically inert filler, usually of mineral origin, such as talc, china clay, etc.
The use of mineral fillers in papers is practiced, above all, for the reason that these additives improve the paper's printing properties. There are two different ways in which the filler may be added: by admixture to the paper stock or ~y coating the paper web with iller material. ~rhe present inven-tion reads on a procedure of the first type. When added to the pulp, the ~iller is added in suspension form to the pulp stock 3n slurry prior to its entering the paper machine. To accomplish this, the filler, made up to a 30 to 40 per cent aqueous suspen-sion, is introduced intothe mixing chest preceding the high 112~3~1 consistency stock chest. Talc, for instance, may be added as an aqueous suspensioll on the intake side of the so-called head-box pump.
The quantities used wher, the filler is added to the paper stock vary Erom 2 to 40 per cent~ caLculated on the weight of the completed paper, depending on paper grade. Commonest are filler contents between 5 and 20 per cent. The commonest fillers used are talc, clay (kaolin), chalk, and equivalent. The use of high quality fillers appreciably increasing the opacity of the paper above all, such as titanium oxide and zinc sulphide, has recently increased. It may be observed in catalogue fashion that the use of fillers is intended to improve the opacity and brightness of the paper, to add to its ink recep-tivity, and to imptove the smoothness and finishing capacity.
A problem invariably encountered when using fillers is their mostly unsatisfactory retention to the fibres. It is certainly possible to admix filler material to the pulp stock slurry to produce a homogeneous ayueous suspension of fibres and filler particles. But when this suspension is conducted 2t) onto the paper machine wire, where the water is drawn off and the fibres combine to form a continuous web, what happens is that a considerable proportion of the fillers escape with the water, and the part staying in the web tends to concentrate in one or the other superficial part of the web, giving rise to so-called one-sidedness. It is possible to improve the retention and to eliminate the drawbacks mentioned, in part at least, by using certain additives. As a rule, however, such are compara-tively expensive, and otller disadvantagcs may be associated with them.
The aim of tl-e present invention is to provide a procedure for improving the filler retention without using any special retention aids. This procedure can be contemplated in particular 3~
in the case of paper pulp stock mechanically made from wood, where the fibres ha~e retained their inherent lignin. As stated, lignin at a high enough temperature is soft and sticky, and the partly lignin-covered fibres are then able with ease to bind on their surface a greater amount of filler particles than usual.
However, the said temperature at which lignin displays this property important in view of filler retention only prevails at or immediately after the defibrating step. Therefore, in order to obtain the desired result, the filler must be conducted into contiguity with the fibres at this particular stage.
Although in the following lignin is mentioned with par-ticular emphasis as the constituent of wood or equivalent which undergoes plastic conversion under a temperature increase from 100 to 170 Centigrade, for instance, it is to be noted that certain paper stocks have other constituents, hemicellulose for instance, which become plastic in like manner as lignin, from the viewpoint of the present invention. Therefore, such constituents fall within the scope of the invention as well.
For instance, hardwood pulps and paper stock made of bagasse contain remarhable amounts of hemicellulose, which behaves in a manner substantially similar to the behaviour of lignin, with a view to the invention in hand.
The procedures of prior art for improving the filler retention of paper pulp include for example, a system wherein the improvement of retention is attributable to increased fibril-lation of the cellulose fibres, whereby the filler particles adhere mechanically to the numerous fibrils on the fibres.
In connection with mechanical pulp producing processes, the procedure disclosed in the U.S. Patent No. 3,388,037 is known in the art, wherein additives are introduced into the refiner grinder, the purpose being to achieve a bleaching effect. However, a chemical reaction between the fibre material and the additives is concerned in this case.
~12~30~
It should be underlined in particular that the aim of the present invention is to improve the retention by physical means, in other words making use of the ability of th~ lignin in the fibres to bind, like glue, filler particles on the fibre surf~cc at a givcn tcmperaturc.
~ ccording to the present invention, there is provided a method ~or improving the properties of a paper pulp stock manufactured by comminuting wood material mechanically and for increasing the retention grade of the filler material in the pulp with the purpose of improving without a chemical reaction the optical and printing properties of the paper made from the said pulp which pulp is made by defibrating wood,charac-terized in that filler materials are added to and mixed with the fibrous material in the defiberizing machine, during the defibration process in such a process phase, when the lignin or equivalent bound to the fibers, as a result of the high temperature generated during the defibration process is soft plasticized and sticky and is able in enhanced manner to make the filler material particles adhere to the surface of the fibers.
In the following, the invention is described in detail with reference being made to an embodiment example, presented in the figures Gf the attached drawing, to which it is not in any way confined.
The figure presents a more detailed embodiment example of the process of the invention.
The grinding machine shown in the figure comprises a chamber 1 for the loys 2 to be ground, a grinding stone 3 rotating in the direction indicated by arrow, and below the stone, a pulp pit 4. Means known in themselves in prior art, such as hydraulically plunger (not depicted) for instance, are employed to urge the logs 2 against the surface of the stone. The water indispensable in the grinding process is - '112~3~
directed on the surface of the stone by means of the jet pipe 5. The pulp produced in the process collects as a fibre/water suspension 9 in the pit - 5a ~
l~ZV301 4 ullder the stone and rulls ~ver the over10w weir 8 into the cllannel 10, wl~el~ce the stock is [orwarded by the pump 11 to a screening apparatus (not depicted) for the removal of splillters etc., and f~rther to the papcr rnakiny process. The grindiny stone and stock pit are enclosed in a hermetically sealed chamber 12, where it is possible if required to maintain an over-pressure e.g. by the aid of compressed air introduced through the line 14, provided with valve 13. The stock pit 4 comprises an extension part 16 with mixer 15 and which has been provided with an incomplete partition 17, this partition guiding the contin~ous stock flow entering the pit ~o flow through the extension part of the pit towards the overflow. The apparatus also comprises a jet pipe 6, through which filler suspension is conducted onto the surface of the grinding stone in the form of a suspension of approximately 30 to 40 per cent. Another jet pipe 7 has been provided to supply filler in among the pulp on the surface of the stone. The introduction of filler material may be through one of the two jet pipes only, or using both, depending on circumstances. To the pit 4 is connected a steam pipe 19 with valve 13 for the heating of the pulp 9 in case additional heat is required in the process. The task of the mixer 15 is, on one hand, to maintain the pulp flow through thc extension part 16 and, on the other hand, to provide for eEficient admixture of the filler to the stock.
The power brought to the shaft of the grinding stone 3 is converted to heat in the grinding process, and the temperature of the fibre pulp produced may in the grinding zone rise to a remarkable level (100 to 130 Centigrade~, similarly as in the process wherein a disk refiner is used. E~ereby the lignin or equivalent in the fibres softens and becomes sticky, It is however necessary to dilute the fibre stock obtained by grinding, to a consistency such that it can be pumped. The ;)3V~
ad(lillg o~ dilution water, whic}l may be accomplished through the jet pipe (5a), rapidly lowers the temperature of the pulp sus-pension far below 100 Centigrade.
If it is desired to utilize the capacity of lignin-containing fibres to bind filler material on thei~ surface, the addition or filler must take place in connection with or imrne~iately after the grinding event. The Eiller suspension may be conducted onto the bare surface of the grinding stone at a point before the grinding zone. But if this should inter-fere with the grinding event, it is also possible to perEorm -the filler addition immediately after the grinding zone, onto the pulp-covered surface of the grinding stone.
In order to ensure adhesion of the filler particles, endeavours should be taken to prolong the dwelling time of the pulp in the stone pit, this being done by increasing the capacity of the pit with the aid of an extension part. The same end, i.e., positive fixation of the filler, is served by the mixer placed within the extension part and by the possibility of heating the pulp with the aid o~ steam.
It is well known that the production of high grade ground-wood implies that the logs subjected to the process are wet and that enoug water is present in the grinding process proper.
The large heat quantity produced in the process and the temper-ature rise past 100 Centigrade may result in fast evaporation of water and drying out of the material in the grinding zone.
It is possible with a view to preventing this, to carry out the grinding process in a pressure-tight volume in which an over-pressure is maintained with the aid of compressed air, or in-stance. The over-pressure may also be produced by the aid of the steam used to heat the pulp in the pit under the grinding stone.
Such pulp stock brands are also among the possible ~lZ~)301 applications of the present invention i21 which heretofore no fillers have been used, but in which their use may now be commenced on account of the advantages afforded by the inven-tion. These applications irlclude newsprints particularly when endeavours are to reduce the base weight of newsprint, which is a general aspiration nowadays. This now becomes possible, especially owing to the improved opacity of the paper.
The invention is in no way narrowly confined to the embodiment examples described above by way of example alone, of which various details may vary within the inventive idea laid down in the claims stated below.
Claims (17)
1. A method for improving the properties of a paper pulp stock manufactured by comminuting wood material mechanic-ally and for increasing the retention grade of the filler material in the pulp with the purpose of improving without a chemical reaction the optical and printing properties of the paper made from the said pulp which pulp is made by defibrating wood,characterized in that filler materials are added to and mixed with the fibrous material in the defiberizing machine during the defibration process in such a process phase, when the lignin or equivalent bound to the fibers, as a result of the high temperature generated during the defibration process is soft plasticized and sticky and is able in enhanced manner to make the filler material particles adhere to the surface of the fibers.
2. A method according to claim 1 characterized in that the addition of filler material takes place prior to the defi-bration process.
3. A method according to claim 1 characterized in that the addition of filler material takes place immediately after the defibration process.
4. A method according to claim 1, characterized in that defibration takes place in a pressurized volume.
5. A method according to claim 4 characterized in that the overpressure is accomplished by means of steam introduced in the pulp.
6. A method according to claim 1, 2, 3, characterized in that the affixing of the filler material takes place in a pulp stock tank in connection with the defibrating machine.
7. A method according to claim 1, wherein said wood is in the form of logs.
8. In the production of mechanical paper pulp from natural vegetable fibrous raw material such as wood by friction-ally acting upon a natural vegetable fibrous raw material contain-ing plasticizable constituents to at least partially separate the fibers thereof from each other while heating the plasticizable constituents thereof to a temperature sufficiently high to plas-ticize the same rendering the pasticizable constituents soft and sticky, the method of improving the quality and properties of pulp produced therefrom which comprises adding at least one paper filler material which is not chemically reactive with the pulp when added and at such time that it comes into contact with the plasticizable constituents of the pulp while the same are in softened and sticky condition so that the filler material adheres to but does not chemically react with the fibers of the pulp to result in improvement of the properties of the pulp.
9. In the method of claim 8 wherein said fibrous raw material is acted upon frictionally by a defibrating action and wherein said filler material is added during the defibrating of the raw material.
10. In the method of claim 8, and wherein the fibrous raw material is acted upon frictionally in a two stage defibrating operation and wherein the filler material is added to the pulp between the two defibrating stages.
11. In the method of claim 8, 9 or 10, wherein said fibrous raw material is acted upon frictionally by defibrating action and wherein said filler material is added to the fibrous raw material before the mechanical defibrating action.
12. In the method of claim 8, 9 or 10, wherein the fibrous raw material is acted upon frictionally by a defibrating action and wherein the filler material is added to the produced mechanical paper pulp after its defibration but while it is still sufficiently hot after the mechanical defibration action so that the pasticizable constituents of the fibers are still in softened and sticky condition.
13. In the method of claim 8, wherein the defibration is effected under pressure.
14. In the method of claim 13, wherein the increased pressure is effected by introduction of gas.
15. In the method of claim 13 and wherein the increased pressure is accomplished by the introduction of steam to the pulp.
16. In the method of claim 8, g or 10, wherein said filler is selected from the group consisting of kaolin, talc, gyp-sum, chalk, calcium carbonate, barium sulfate, silica, titanium dioxide and zinc sulfide.
17. In the method of claim 8, 9 or 10, wherein said filler is talc.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI783193A FI57978C (en) | 1978-10-19 | 1978-10-19 | FOERFARANDE FOER FRAMSTAELLNING AV SLIPMASSA OCH FOER FOERBAETTRING AV DESS EGENSKAPER |
| FI783193 | 1978-10-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1120301A true CA1120301A (en) | 1982-03-23 |
Family
ID=8512087
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000337933A Expired CA1120301A (en) | 1978-10-19 | 1979-10-18 | Method for improving of paper pulp stock manufactured mechanically from wood |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5557090A (en) |
| BR (1) | BR7906762A (en) |
| CA (1) | CA1120301A (en) |
| DE (1) | DE2941675A1 (en) |
| FI (1) | FI57978C (en) |
| FR (1) | FR2439263A1 (en) |
| GB (1) | GB2035839B (en) |
| IT (1) | IT1125495B (en) |
| NO (1) | NO793357L (en) |
| SE (1) | SE7908578L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109537337A (en) * | 2018-07-16 | 2019-03-29 | 广西综改咨询服务有限公司 | A kind of paper grade (stock) timber crushing grinding device |
-
1978
- 1978-10-19 FI FI783193A patent/FI57978C/en not_active IP Right Cessation
-
1979
- 1979-10-15 GB GB7935759A patent/GB2035839B/en not_active Expired
- 1979-10-15 DE DE19792941675 patent/DE2941675A1/en not_active Withdrawn
- 1979-10-17 SE SE7908578A patent/SE7908578L/en not_active Application Discontinuation
- 1979-10-18 NO NO793357A patent/NO793357L/en unknown
- 1979-10-18 CA CA000337933A patent/CA1120301A/en not_active Expired
- 1979-10-18 IT IT26605/79A patent/IT1125495B/en active
- 1979-10-19 BR BR7906762A patent/BR7906762A/en unknown
- 1979-10-19 JP JP13504979A patent/JPS5557090A/en active Pending
- 1979-10-19 FR FR7926075A patent/FR2439263A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| SE7908578L (en) | 1980-04-20 |
| BR7906762A (en) | 1980-06-03 |
| DE2941675A1 (en) | 1980-04-30 |
| JPS5557090A (en) | 1980-04-26 |
| FR2439263A1 (en) | 1980-05-16 |
| NO793357L (en) | 1980-04-22 |
| FI57978C (en) | 1980-11-10 |
| GB2035839B (en) | 1982-10-27 |
| FR2439263B3 (en) | 1981-08-14 |
| IT7926605A0 (en) | 1979-10-18 |
| FI57978B (en) | 1980-07-31 |
| IT1125495B (en) | 1986-05-14 |
| FI783193A (en) | 1980-04-20 |
| GB2035839A (en) | 1980-06-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |