CA1232713A - Paper-making method - Google Patents
Paper-making methodInfo
- Publication number
- CA1232713A CA1232713A CA000452222A CA452222A CA1232713A CA 1232713 A CA1232713 A CA 1232713A CA 000452222 A CA000452222 A CA 000452222A CA 452222 A CA452222 A CA 452222A CA 1232713 A CA1232713 A CA 1232713A
- Authority
- CA
- Canada
- Prior art keywords
- pulp
- strength
- filler
- paper
- added
- 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
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Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
- D21H17/375—Poly(meth)acrylamide
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
- D21H17/24—Polysaccharides
- D21H17/28—Starch
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/33—Synthetic macromolecular compounds
- D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- D21H17/53—Polyethers; Polyesters
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Paper (AREA)
- Diaphragms For Electromechanical Transducers (AREA)
- Making Paper Articles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A novel method is provided herein for making paper or paperboard with a higher dry strength than previously by adding to the fiber pulp suspension a smaller amount than previously of cationic, water-soluble starch and a synthetic retention agent.
In addition, a filler can be added to the fiber pulp suspension.
According to the invention, cationic, water-soluble starch is added to the fiber pulp suspension at only 0.02-1.5% (as calculated from the dry weight of the pulp) and the synthetic retention agent (which is selected from the group consisting of polyacrylamides, their derivatives and copolymers), is added at only 0.005-0.1%, (also as calculated from the dry weight of the pulp). The addition can be made either to a fiber pulp suspension which is substantially free from filler, or part of the retention agent may be added to the fiber pulp suspension before the adding of the filler, or a pre-treated filler may be added to the fiber pulp at some other stage.
A novel method is provided herein for making paper or paperboard with a higher dry strength than previously by adding to the fiber pulp suspension a smaller amount than previously of cationic, water-soluble starch and a synthetic retention agent.
In addition, a filler can be added to the fiber pulp suspension.
According to the invention, cationic, water-soluble starch is added to the fiber pulp suspension at only 0.02-1.5% (as calculated from the dry weight of the pulp) and the synthetic retention agent (which is selected from the group consisting of polyacrylamides, their derivatives and copolymers), is added at only 0.005-0.1%, (also as calculated from the dry weight of the pulp). The addition can be made either to a fiber pulp suspension which is substantially free from filler, or part of the retention agent may be added to the fiber pulp suspension before the adding of the filler, or a pre-treated filler may be added to the fiber pulp at some other stage.
Description
~Z327~3 The invention relates to a paper-making method in which a polysaccharide-type additive is used together with a synthetic retention agent in order to improve the dry strength properties of paper or to make the paper less expensive.
The principal raw material in making paper and paper board is a pulp prepared from wood by either chemical or mechanical methods. Depending on the process, the term used is either chemical pulp or mechanical pulp. The other raw-material components used are fillers (kaolin, talc, Cook, etc.) and various additives. Fillers are used on the one hand to decrease the raw-material costs and on the other hand to improve the properties required for printing. The purpose of the additives is to give the product certain specific properties, to improve the filler retention or to increase the strength of the product.
A certain strength is required of paper and paper board in all of its uses. The required degree of strength affects the selection of the raw-material components. Overall, it can be said that a certain pulp component is the more expensive the better the strength it yields. If sufficient strength is not obtained by means of pulp selection, it can be increased by using so-called strength additives. For example, starch, natural gums and polyacrvl aside are such additives. In general it is not possible by means of currently known strength additives to reduce the raw-material costs substantially, for the additional cost due to the strength additives is approximately the same as the achieved decrease in raw-material costs. Nevertheless, it is generally necessary to use these additives in order to meet the ..
~2~7~3 strength requirements.
The amounts of strength additives used in general are for polysaccharide-type dry-strength glues 0.5-2 % and for natural gums and polyacryl asides 0.2-1 of the dry weight of the pulp.
In earlier years the filler retention was achieved by using alum. When the speed of paper-making machines increased, the effectiveness of alum was no longer sufficient, and there was a shift to the use of synthetic polymers, mainly polyacrvl asides. Recently there has been a shift to the use of increasing amounts of filler, on the one hand for reasons of cost and on the other hand in order to achieve better results in printing. In such cases, difficulties with paper strengths have been encountered in some mills, and for this reason strength additive has been added to the pulp. This known joint use has not led to any surprising increase in strengths. The provable reason for this has been the phenomenon that the filler has, more strongly than the other pulp components, adsorbed the retention agent added.
The joint use of a cat ionic starch and an anionic polyacryl aside type retention assent is also known in the making of so-called super-filled papers. It has been sugcrested that such paper types,havillg filler contents twice or three times writer than the normal proportion should be made by using such combination of additives (STFI-kontakt No. 3, 1932, pp. I For example, 5 cat ionic starch and 0.3 I
anionic polyacryl aside can be used in the making of a paper which contains 50 % kaolin. According to such publication, the use of such a cat ionic starch together with an anionic polymer is based on the fact that the kink and tune anionic component is each batched in the 3 12;~7~3 same proportion with respect to its charge, whereby the starch is caused to precipitate and to remain in the paper in amounts hither than the adsorption capacity of tune pulp.
The improvement obtained using a filler content of 0 is surprisingly small. A corresponding result should be obtained by proportioning only starch at 2 %.
In a laboratory investigation (TAIPEI 59 (1976); 6, 120-122) it was observed that a cat ionic starch and an anionic polyacryl aside also act as a double-component retention agent col~ination. The strength effect was not investigated in the experiments. In these experiments also, a filler, 5-10 Tokyo, was used, and the proportioning of the additives was carried out on the basis of charge optimization.
An acryl aside optimally having a molecular weight between Lowe and 500,000 can be used as a dry-strength sizing in paper. Combinations of such an anionic acryl aside and a cat ionic starch or natural gum have been experimented with as a dry-strength sizing without noteworthy positive results JO Casey: Pulp and Paper Chemistry and Chemical Technology, 3rd Ed., vol. III, Wiley & Sons 1981, p. 1456).
The reason for the poor result was probably an incorrect selection of the conditions.
Thus it has now been observed surprisingly that it is possible to arrange the use of a ?olysaccharide-type additive and a synthetic polymeric retention agent in such a way that an improvement une~pectedlv great with respect to what is known previously can be achieve in the dry strength properties of paper or paper board by using smaller runts of the additives than previously.
~X327~3 - pa -By one broad aspect of this invention, a method is provided for making paper and paper board, comprising adding, to a fiber pulp suspension, from 0.2 to 1.5% of cat ionic, water soluble starch and from 0.005 to 0.1% of a synthetic retention agent comprising at least one compound selected from the group consisting of polyacrylamides, their derivatives and copolymers, the amounts of such additives being calculated from the dry weight of pulp.
By another broad aspect of this invention, a method is lo provided for making paper and paper board, comprising adding, to a fiber pulp suspension, from 0.2 -.1.5% of cat ionic, water soluble starch and from 0.005 - 0.1% of at least one compound selected from the group consisting of polyacryl asides, its derivatives and copolymers, the amounts of such additives being calculated from the dry weight of the pulp; and adding a filler to the fiber pulp suspension, at least part of the retention agent being added to the fiber pulp suspension before the addition of the filler.
In these aspects of the invention, the filler may be a pretreated filler.
It is preferred that the amount of synthetic retention agent, added to the fiber pulp suspension, be in an amount of 0.02 - 0.05~, as calculated from the dry weight of the pulp.
At least part of the polysaccharide-type additive may be added to the fiber suspension before the synthetic retention agent is added thereto.
~327~3 By a polysaccharide-type additive is meant here those polyp saccharides and their derivatives or mixtures which are intended to be added to paper pulp, which are mainly known as dry-strength additives and winch are described in greater detail in the above-mentioned work JO Casey, pp. 1475-1514). These agents can be used to affect, in addition to the dry strength, also the separation of water from the web in the paper machine, the optimal formation of the paper web, and especially in the case of the derivatives, retention and even the wet strength. These agents have an ability to form hydrogen bonds with cellulose and thereby to increase paper strength. Owing to price factors, those of these polysaccharide-type additives which are used most frequently are starches and their derivatives. Cationated starches are preferred in use because of their good retention properties.
Natural gums (e.g. guard gum and its derivatives), allegiant, and cellulose derivatives , e.g., carboxymethyl cellulose, methyl cellulose and hydroxyethyl cellulose are further polysaccharide-type additives useful herein.
The synthetic retention agents useful herein are high-molecular-weight, long-chain polymers , e.g., polyethylene oxide or polyacryl asides, the latter either as such or hydrolyzed in part or completely, or substituted or co-polymerized. Polyethylene oxide is non ionic, and its molecular weight is advan.aseously over 1,000,000. The polyacryl asides may be anionic, cat ionic or non ionic, and their molecular eights are over 200,000, preferably over 1,000,000. The use of the substances as a combination or a mixture is also possible.
my substantially filler-free paper or paper board types is here meant those which have been made without using any fillers or only small amounts of fillers, at maximum 10 and in general less than 5 JO.
. .
lZ3Z~
The retention of cat ionic starch at the proportions used as described herein is 90-100 I (Casey, pp. 149~, 1495). It is thus not probable that the increase in strength obtained hurricane would be based on producing a substantial improvement in strength through the improvement of the retention of the polysaccharide additive by means of the retention agent (contrary to known methods, in which strength is increased by precipitating a polyp saccharide-type additive by means of a polymer having an opposite charge in such a way that the increase in strength is due to it).
On the other hand, the retention additive used herein does not alone have a noteworthy strength-increasing effect when the amount used remains at the level used herein i. e. in the order of magnitude corresponding to the normal use of retention agent. Thus the surprising effect is probably based or a strong synergistic action of the agents used.
In the method provided herein, the retention agent is selected case by case by using known methods, e.g., laboratory-scale retention tests in such a way that the optimal retention result is obtained. It depends on the conditions (effects of the pulp, water, sizincr, etc.) whether the best result is obtained by means of an avionic a catior.ic or a nor ionic retention agent. The method thus deviate from the Norway. method in that the charges of the polysaccharide-.vDe additive and the retention agent need not coarsely out each owner, not even be if. opposition.
The method described hurricane can be used advantageously when making papers and paper boards free or nearly -fee from mineral tillers, cog., raft paper, newsprint and paper board. The utilization of the ~l~th~d 1~327~3 is, however, not limited to the making of these. However, when filler-containing types of paper are made it is necessary to take into consideration the general tendency of retention agents to be adsorbed primarily to the surfaces of filler particles. When the retention agent proportion is increased above the amount adsorbed by the fillers in such a way that the retention agent can act in the manner required as described herein and adhere to the fibers, it is often necessary to use uneconomically large amounts of the additive. Therefore it is advantageous to carry out the making of filler-containing paper.
In such a way that the filler is treated separately with a retention agent found to be suitable for it (which may be the same as the retention agent described herein above), and thereafter the filler is added to a pulp treated as described above. another method is to pretreat the filler by some method known per so (e.g. by the method described in the above-mentioned STFI-kontakt publication: cat ionic starch is obtained on the filler surface when the filler is first dispersed anionic ally).
Thereby the character of the filler surface entirely changes, in which case it can possibly be mixed with the pulp even before the adding of the retention agent, without losing the strength advantage obtainable by means of the polymer system described herein. The pretreatment of the filler can, of course, also be arranged so as to take place in the presence of the pulp.
1~327~3 Some embodiments of the invention are described in -the following examples.
Example 1 The pulp mixture was 50~ chemical pulp, 50% mechanical pulp.
The pulp was taken from the head box, and 0.7~ of a cat ionic starch, known by the Trade Mark PIECEMEAL B of Avebe, and, in order to obtain the desired degree of sizing, 0.125~ of a resin glue known by the Trade Mark of T-GLUE of Hercules, and 0.4~ alum had been added to the pulp in the vat of the machine. To the pulp lo were added different amounts of the anionic polyacrylamide which had been determined to be the most suitable for use with the pulp, and in the second test series first 0.4% cat ionic starch and thereafter the different amounts of the polymer. 60 g/m2 sheets were prepared from the pulp, and the sheets were tested.
The results were as follows:
Polyacryl Pulp (contains 0.7 % Pulp (contains 0.7 %
aside cat ionic starch) cat ionic starch) + 0.4 %
cat ionic starch % Bonding Tensile Bonding Tensile strength strength strength strength J/m2 Kim J/m2 em O (known) 185 2.55 1~0 2.80 0.01 185 2.80 265 3.05 0.02 230 3.0 300 3.05 0.03 240 3.0 360 3.3 0.04 250 I 530 3.32 ~23271.~3 - pa -The results show that the strength of the sheets was improved even with an addition of 0.01~ polyacrylamide.
According to the state of the art, polyacrylamide additions this small should not notably affect the strength of the pulp.
Example 2 As Example 1, except that the pulp was taken from the point prior to the vat of the machine, i.e. it contained no additive.
The sizing substances were added to the pulp first, then the polyacryl aside and last 0.4~ cat ionic starch. The results were:
~Z327~
Polyaeryl aside, 0 0.01 0.02 0.03 Bonding strength, J/m2 110 125 125 135 The bonding strength was lower than in Example 1, since the amount of eationie stanch was 0.7 % less. Nevertheless, the results show that an addition of polvaeryl aside has an improving effect on paper strengths.
Example 3 As Example 2, but the stanch was added before the polyareyl aside, and also its amount was varied. The results were as follows:
C a t i o n 1 e s t a r e h , %
Polyaervl 0.4 0.6 0.8 amide,Bonding Tensile Bonding Tensile Bonding Tensile strength strength strength strength strength strength J/m2 Kim J/m2 Kim J/m2 Kim 0 105 1.48 105 1.70 115 1.65 0.01 120 1.70 120 1.82 120 1.85 0.02 135 1.98 135 2.10 140 2.20 0.03 155 2.30 220 2.35 (test disk -continued) In several investigations pertaining to the paper-making industry it has occurred that promising results obtained on a laboratory scale have not been valid in an industrial-scale machine. Therefore, the chemical system d~scribcd hcr~in was experimented -with in a paper board machine.
The mushier was of the Ir.~erform type. The surface and backc3round layers are made from pure chemical pulp, and 50 Jo mechanical pulp is used for the middle layer.
additional use of mechanical pulp is limited by the bonding strength of the complete paper board. It is normally 85-90 J/m2, and in this case kosher stanch is added at Go %
~232~3 to the pulp of the middle layer. Also larger proportions, up to 2 %, have been experimented with, but without results.
Example 4 A trial run was carried out in the mill. Cat ionic starch was batched continuously into the vat of the machine. Its proportion varied between 0.6 and 1.2 I . In this case the bonding strength was about 90 J~m2. Polyacryl aside was added at a point subsequent to the sieves, and its proportion was gradually increased. When the proportion increased to 0.042 grow the bonding strength increased to 120 J/m2.
En e 5 A second trial run was carried out in the mill. In this experiment 1.2 go cat ionic starch was batched continuously into the machine. The proportion and batching place of polyacryl aside was varied and, in addition, at certain-test stations an additional amount of starch was batched after the ~olyacryl aside. In each case the best results and the polyacryl aside amounts required for them were as follows:
Batching of additives Bonding strength J/m2 _ 85-90 0.045 JO polyacryl am~cie subsequent to the sieves 125 0 . 025 pa polyacryl aside prior to the sieves + 0 . b ^^` catioric starch subsequent to the 170 sieges 0.025 polyacryl aside prior to the mlxin(3 pumps + 0.6 catior.ic starch subsequent 150 to like sieves EYa-~l~ 6 my cclrryir.a Gut experiments with a laboratory skeet mold, ~2327~3 1 () the effect of different polyacryl aside type retention agents on the dry strength of paper was investigated. The pulp contained 45 % cellulose and 55 grounded. The pulp was taken from the equalizing box, and it contained 1.2 %
cat ionic starch 60 g/m sheets were prepared from the pulp by using a circulating-water mold, and 0.02 polyacryl aside was added to the pulp immediately before the pulp was poured into the sheet mold. The results were:
Ion charge of the polyacryl sounding strength, aside type retention agent J~m2 (without retention agent) 332 cat ionic 389 non ionic 357 anionic 388 It is observed that the best result is obtained by using either a cat ionic or an anionic retention agent, i.e. both a cat ionic and an anionic polyacryl aside yield a high strength in conjunction with a cat ionic starch.
Example 7 The experiment according to Example 6 was repeated, except that the pulp used was a pulp containing 23 JO waste cellulose and 77 grounded, the amount of cat ionic starch was 0 7 coy and the polyacryl aside proportion was 0.03 ^~. The sheets were made 100 J/m , without circulating water. The results were:
Ion charge of the polyacryl Budding Tersely aside type retention aaerlt strength index J/m Nag without retention agent) 102 17.5 cat ionic 133 18.5 mildly anionic 124 18.7 strongly anionic 137 18.0 It 12327~
It is again observed that tune advantageous joint effect together with a cat ionic starch is obtained with both an anionic and a cat ionic polyacryl aside.
Example 8 ..
60 J/m circulatinc,l-water sleets were prepared by using a laboratory sheet mold, from a pulp containing 25 so ground-wood and 75 % reject folding box board. In ample time (at least 0.5 h) prior to sheet making, either native guard gum or amphoteric guard gum was added to the pulp. The proportion to of each was 1.2 %. Immediately before the pulp was poured into the sheet mold, 0.03 JO various polyacryl aside type retention agents were added to it. The results were:
bonding strength, J/m2 zero experiment (no natural gum and no retention agent) 177 guard gum, native 270 guard gum, amphoteric 2~8 It is observed that an advantageous joint effect similar to that obtained using cat ionic combinations of starch and a retention agent can be obtained also by using combinations of a natural gum and a retention agent.
The principal raw material in making paper and paper board is a pulp prepared from wood by either chemical or mechanical methods. Depending on the process, the term used is either chemical pulp or mechanical pulp. The other raw-material components used are fillers (kaolin, talc, Cook, etc.) and various additives. Fillers are used on the one hand to decrease the raw-material costs and on the other hand to improve the properties required for printing. The purpose of the additives is to give the product certain specific properties, to improve the filler retention or to increase the strength of the product.
A certain strength is required of paper and paper board in all of its uses. The required degree of strength affects the selection of the raw-material components. Overall, it can be said that a certain pulp component is the more expensive the better the strength it yields. If sufficient strength is not obtained by means of pulp selection, it can be increased by using so-called strength additives. For example, starch, natural gums and polyacrvl aside are such additives. In general it is not possible by means of currently known strength additives to reduce the raw-material costs substantially, for the additional cost due to the strength additives is approximately the same as the achieved decrease in raw-material costs. Nevertheless, it is generally necessary to use these additives in order to meet the ..
~2~7~3 strength requirements.
The amounts of strength additives used in general are for polysaccharide-type dry-strength glues 0.5-2 % and for natural gums and polyacryl asides 0.2-1 of the dry weight of the pulp.
In earlier years the filler retention was achieved by using alum. When the speed of paper-making machines increased, the effectiveness of alum was no longer sufficient, and there was a shift to the use of synthetic polymers, mainly polyacrvl asides. Recently there has been a shift to the use of increasing amounts of filler, on the one hand for reasons of cost and on the other hand in order to achieve better results in printing. In such cases, difficulties with paper strengths have been encountered in some mills, and for this reason strength additive has been added to the pulp. This known joint use has not led to any surprising increase in strengths. The provable reason for this has been the phenomenon that the filler has, more strongly than the other pulp components, adsorbed the retention agent added.
The joint use of a cat ionic starch and an anionic polyacryl aside type retention assent is also known in the making of so-called super-filled papers. It has been sugcrested that such paper types,havillg filler contents twice or three times writer than the normal proportion should be made by using such combination of additives (STFI-kontakt No. 3, 1932, pp. I For example, 5 cat ionic starch and 0.3 I
anionic polyacryl aside can be used in the making of a paper which contains 50 % kaolin. According to such publication, the use of such a cat ionic starch together with an anionic polymer is based on the fact that the kink and tune anionic component is each batched in the 3 12;~7~3 same proportion with respect to its charge, whereby the starch is caused to precipitate and to remain in the paper in amounts hither than the adsorption capacity of tune pulp.
The improvement obtained using a filler content of 0 is surprisingly small. A corresponding result should be obtained by proportioning only starch at 2 %.
In a laboratory investigation (TAIPEI 59 (1976); 6, 120-122) it was observed that a cat ionic starch and an anionic polyacryl aside also act as a double-component retention agent col~ination. The strength effect was not investigated in the experiments. In these experiments also, a filler, 5-10 Tokyo, was used, and the proportioning of the additives was carried out on the basis of charge optimization.
An acryl aside optimally having a molecular weight between Lowe and 500,000 can be used as a dry-strength sizing in paper. Combinations of such an anionic acryl aside and a cat ionic starch or natural gum have been experimented with as a dry-strength sizing without noteworthy positive results JO Casey: Pulp and Paper Chemistry and Chemical Technology, 3rd Ed., vol. III, Wiley & Sons 1981, p. 1456).
The reason for the poor result was probably an incorrect selection of the conditions.
Thus it has now been observed surprisingly that it is possible to arrange the use of a ?olysaccharide-type additive and a synthetic polymeric retention agent in such a way that an improvement une~pectedlv great with respect to what is known previously can be achieve in the dry strength properties of paper or paper board by using smaller runts of the additives than previously.
~X327~3 - pa -By one broad aspect of this invention, a method is provided for making paper and paper board, comprising adding, to a fiber pulp suspension, from 0.2 to 1.5% of cat ionic, water soluble starch and from 0.005 to 0.1% of a synthetic retention agent comprising at least one compound selected from the group consisting of polyacrylamides, their derivatives and copolymers, the amounts of such additives being calculated from the dry weight of pulp.
By another broad aspect of this invention, a method is lo provided for making paper and paper board, comprising adding, to a fiber pulp suspension, from 0.2 -.1.5% of cat ionic, water soluble starch and from 0.005 - 0.1% of at least one compound selected from the group consisting of polyacryl asides, its derivatives and copolymers, the amounts of such additives being calculated from the dry weight of the pulp; and adding a filler to the fiber pulp suspension, at least part of the retention agent being added to the fiber pulp suspension before the addition of the filler.
In these aspects of the invention, the filler may be a pretreated filler.
It is preferred that the amount of synthetic retention agent, added to the fiber pulp suspension, be in an amount of 0.02 - 0.05~, as calculated from the dry weight of the pulp.
At least part of the polysaccharide-type additive may be added to the fiber suspension before the synthetic retention agent is added thereto.
~327~3 By a polysaccharide-type additive is meant here those polyp saccharides and their derivatives or mixtures which are intended to be added to paper pulp, which are mainly known as dry-strength additives and winch are described in greater detail in the above-mentioned work JO Casey, pp. 1475-1514). These agents can be used to affect, in addition to the dry strength, also the separation of water from the web in the paper machine, the optimal formation of the paper web, and especially in the case of the derivatives, retention and even the wet strength. These agents have an ability to form hydrogen bonds with cellulose and thereby to increase paper strength. Owing to price factors, those of these polysaccharide-type additives which are used most frequently are starches and their derivatives. Cationated starches are preferred in use because of their good retention properties.
Natural gums (e.g. guard gum and its derivatives), allegiant, and cellulose derivatives , e.g., carboxymethyl cellulose, methyl cellulose and hydroxyethyl cellulose are further polysaccharide-type additives useful herein.
The synthetic retention agents useful herein are high-molecular-weight, long-chain polymers , e.g., polyethylene oxide or polyacryl asides, the latter either as such or hydrolyzed in part or completely, or substituted or co-polymerized. Polyethylene oxide is non ionic, and its molecular weight is advan.aseously over 1,000,000. The polyacryl asides may be anionic, cat ionic or non ionic, and their molecular eights are over 200,000, preferably over 1,000,000. The use of the substances as a combination or a mixture is also possible.
my substantially filler-free paper or paper board types is here meant those which have been made without using any fillers or only small amounts of fillers, at maximum 10 and in general less than 5 JO.
. .
lZ3Z~
The retention of cat ionic starch at the proportions used as described herein is 90-100 I (Casey, pp. 149~, 1495). It is thus not probable that the increase in strength obtained hurricane would be based on producing a substantial improvement in strength through the improvement of the retention of the polysaccharide additive by means of the retention agent (contrary to known methods, in which strength is increased by precipitating a polyp saccharide-type additive by means of a polymer having an opposite charge in such a way that the increase in strength is due to it).
On the other hand, the retention additive used herein does not alone have a noteworthy strength-increasing effect when the amount used remains at the level used herein i. e. in the order of magnitude corresponding to the normal use of retention agent. Thus the surprising effect is probably based or a strong synergistic action of the agents used.
In the method provided herein, the retention agent is selected case by case by using known methods, e.g., laboratory-scale retention tests in such a way that the optimal retention result is obtained. It depends on the conditions (effects of the pulp, water, sizincr, etc.) whether the best result is obtained by means of an avionic a catior.ic or a nor ionic retention agent. The method thus deviate from the Norway. method in that the charges of the polysaccharide-.vDe additive and the retention agent need not coarsely out each owner, not even be if. opposition.
The method described hurricane can be used advantageously when making papers and paper boards free or nearly -fee from mineral tillers, cog., raft paper, newsprint and paper board. The utilization of the ~l~th~d 1~327~3 is, however, not limited to the making of these. However, when filler-containing types of paper are made it is necessary to take into consideration the general tendency of retention agents to be adsorbed primarily to the surfaces of filler particles. When the retention agent proportion is increased above the amount adsorbed by the fillers in such a way that the retention agent can act in the manner required as described herein and adhere to the fibers, it is often necessary to use uneconomically large amounts of the additive. Therefore it is advantageous to carry out the making of filler-containing paper.
In such a way that the filler is treated separately with a retention agent found to be suitable for it (which may be the same as the retention agent described herein above), and thereafter the filler is added to a pulp treated as described above. another method is to pretreat the filler by some method known per so (e.g. by the method described in the above-mentioned STFI-kontakt publication: cat ionic starch is obtained on the filler surface when the filler is first dispersed anionic ally).
Thereby the character of the filler surface entirely changes, in which case it can possibly be mixed with the pulp even before the adding of the retention agent, without losing the strength advantage obtainable by means of the polymer system described herein. The pretreatment of the filler can, of course, also be arranged so as to take place in the presence of the pulp.
1~327~3 Some embodiments of the invention are described in -the following examples.
Example 1 The pulp mixture was 50~ chemical pulp, 50% mechanical pulp.
The pulp was taken from the head box, and 0.7~ of a cat ionic starch, known by the Trade Mark PIECEMEAL B of Avebe, and, in order to obtain the desired degree of sizing, 0.125~ of a resin glue known by the Trade Mark of T-GLUE of Hercules, and 0.4~ alum had been added to the pulp in the vat of the machine. To the pulp lo were added different amounts of the anionic polyacrylamide which had been determined to be the most suitable for use with the pulp, and in the second test series first 0.4% cat ionic starch and thereafter the different amounts of the polymer. 60 g/m2 sheets were prepared from the pulp, and the sheets were tested.
The results were as follows:
Polyacryl Pulp (contains 0.7 % Pulp (contains 0.7 %
aside cat ionic starch) cat ionic starch) + 0.4 %
cat ionic starch % Bonding Tensile Bonding Tensile strength strength strength strength J/m2 Kim J/m2 em O (known) 185 2.55 1~0 2.80 0.01 185 2.80 265 3.05 0.02 230 3.0 300 3.05 0.03 240 3.0 360 3.3 0.04 250 I 530 3.32 ~23271.~3 - pa -The results show that the strength of the sheets was improved even with an addition of 0.01~ polyacrylamide.
According to the state of the art, polyacrylamide additions this small should not notably affect the strength of the pulp.
Example 2 As Example 1, except that the pulp was taken from the point prior to the vat of the machine, i.e. it contained no additive.
The sizing substances were added to the pulp first, then the polyacryl aside and last 0.4~ cat ionic starch. The results were:
~Z327~
Polyaeryl aside, 0 0.01 0.02 0.03 Bonding strength, J/m2 110 125 125 135 The bonding strength was lower than in Example 1, since the amount of eationie stanch was 0.7 % less. Nevertheless, the results show that an addition of polvaeryl aside has an improving effect on paper strengths.
Example 3 As Example 2, but the stanch was added before the polyareyl aside, and also its amount was varied. The results were as follows:
C a t i o n 1 e s t a r e h , %
Polyaervl 0.4 0.6 0.8 amide,Bonding Tensile Bonding Tensile Bonding Tensile strength strength strength strength strength strength J/m2 Kim J/m2 Kim J/m2 Kim 0 105 1.48 105 1.70 115 1.65 0.01 120 1.70 120 1.82 120 1.85 0.02 135 1.98 135 2.10 140 2.20 0.03 155 2.30 220 2.35 (test disk -continued) In several investigations pertaining to the paper-making industry it has occurred that promising results obtained on a laboratory scale have not been valid in an industrial-scale machine. Therefore, the chemical system d~scribcd hcr~in was experimented -with in a paper board machine.
The mushier was of the Ir.~erform type. The surface and backc3round layers are made from pure chemical pulp, and 50 Jo mechanical pulp is used for the middle layer.
additional use of mechanical pulp is limited by the bonding strength of the complete paper board. It is normally 85-90 J/m2, and in this case kosher stanch is added at Go %
~232~3 to the pulp of the middle layer. Also larger proportions, up to 2 %, have been experimented with, but without results.
Example 4 A trial run was carried out in the mill. Cat ionic starch was batched continuously into the vat of the machine. Its proportion varied between 0.6 and 1.2 I . In this case the bonding strength was about 90 J~m2. Polyacryl aside was added at a point subsequent to the sieves, and its proportion was gradually increased. When the proportion increased to 0.042 grow the bonding strength increased to 120 J/m2.
En e 5 A second trial run was carried out in the mill. In this experiment 1.2 go cat ionic starch was batched continuously into the machine. The proportion and batching place of polyacryl aside was varied and, in addition, at certain-test stations an additional amount of starch was batched after the ~olyacryl aside. In each case the best results and the polyacryl aside amounts required for them were as follows:
Batching of additives Bonding strength J/m2 _ 85-90 0.045 JO polyacryl am~cie subsequent to the sieves 125 0 . 025 pa polyacryl aside prior to the sieves + 0 . b ^^` catioric starch subsequent to the 170 sieges 0.025 polyacryl aside prior to the mlxin(3 pumps + 0.6 catior.ic starch subsequent 150 to like sieves EYa-~l~ 6 my cclrryir.a Gut experiments with a laboratory skeet mold, ~2327~3 1 () the effect of different polyacryl aside type retention agents on the dry strength of paper was investigated. The pulp contained 45 % cellulose and 55 grounded. The pulp was taken from the equalizing box, and it contained 1.2 %
cat ionic starch 60 g/m sheets were prepared from the pulp by using a circulating-water mold, and 0.02 polyacryl aside was added to the pulp immediately before the pulp was poured into the sheet mold. The results were:
Ion charge of the polyacryl sounding strength, aside type retention agent J~m2 (without retention agent) 332 cat ionic 389 non ionic 357 anionic 388 It is observed that the best result is obtained by using either a cat ionic or an anionic retention agent, i.e. both a cat ionic and an anionic polyacryl aside yield a high strength in conjunction with a cat ionic starch.
Example 7 The experiment according to Example 6 was repeated, except that the pulp used was a pulp containing 23 JO waste cellulose and 77 grounded, the amount of cat ionic starch was 0 7 coy and the polyacryl aside proportion was 0.03 ^~. The sheets were made 100 J/m , without circulating water. The results were:
Ion charge of the polyacryl Budding Tersely aside type retention aaerlt strength index J/m Nag without retention agent) 102 17.5 cat ionic 133 18.5 mildly anionic 124 18.7 strongly anionic 137 18.0 It 12327~
It is again observed that tune advantageous joint effect together with a cat ionic starch is obtained with both an anionic and a cat ionic polyacryl aside.
Example 8 ..
60 J/m circulatinc,l-water sleets were prepared by using a laboratory sheet mold, from a pulp containing 25 so ground-wood and 75 % reject folding box board. In ample time (at least 0.5 h) prior to sheet making, either native guard gum or amphoteric guard gum was added to the pulp. The proportion to of each was 1.2 %. Immediately before the pulp was poured into the sheet mold, 0.03 JO various polyacryl aside type retention agents were added to it. The results were:
bonding strength, J/m2 zero experiment (no natural gum and no retention agent) 177 guard gum, native 270 guard gum, amphoteric 2~8 It is observed that an advantageous joint effect similar to that obtained using cat ionic combinations of starch and a retention agent can be obtained also by using combinations of a natural gum and a retention agent.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the making of paper and paperboard, comprising adding, to a fiber pulp suspension, from 0.2 to 1.5%
of cationic, water soluble starch and from 0.005 to 0.1% of a synthetic retention agent comprising at least one compound selected from the group consisting of polyacrylamides, their derivatives and copolymers, the amounts of said additives being calculated from the dry weight of pulp.
of cationic, water soluble starch and from 0.005 to 0.1% of a synthetic retention agent comprising at least one compound selected from the group consisting of polyacrylamides, their derivatives and copolymers, the amounts of said additives being calculated from the dry weight of pulp.
2. A method for the making of paper and paperboard, comprising adding, to a fiber pulp suspension, from 0.2 - 1.5% of cationic, water soluble starch and from 0.005 - 0.1% of at least one compound selected from the group consisting of polyacryl-amides, their derivatives and copolymers, the amounts of said additives being calculated from the dry weight of the pulp; and adding a filler to said fiber pulp suspension, at least part of said retention agent being added to said fiber pulp suspension before the addition of said filler.
3. A method according to claim 2 wherein said filler is pretreated.
4. A method according to claims 1, 2 or 3, wherein said synthetic retention agent is added to said fiber pulp suspension in an amount of 0.02 - 0.05%, as calculated from the dry weight of said pulp.
5. A method according to claims 1, 2 or 3, in which at least part of said cationic, water soluble starch is added to said fiber suspension before the addition of said synthetic retention agent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI831,400 | 1983-04-25 | ||
| FI831400A FI71379C (en) | 1983-04-25 | 1983-04-25 | METHOD VID PAPPERSFRAMSTAELLNING |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232713A true CA1232713A (en) | 1988-02-16 |
Family
ID=8517099
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000452222A Expired CA1232713A (en) | 1983-04-25 | 1984-04-17 | Paper-making method |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1232713A (en) |
| DE (1) | DE3412535A1 (en) |
| FI (1) | FI71379C (en) |
| NO (1) | NO163871B (en) |
| SE (1) | SE460730B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5876563A (en) * | 1994-06-01 | 1999-03-02 | Allied Colloids Limited | Manufacture of paper |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0203817A1 (en) * | 1985-05-31 | 1986-12-03 | Betz Europe, Inc. | Polymeric compositions |
| GB8531558D0 (en) * | 1985-12-21 | 1986-02-05 | Wiggins Teape Group Ltd | Loaded paper |
| SE0401600D0 (en) * | 2004-06-18 | 2004-06-18 | Stfi Packforsk Ab | Method of manufacturing paper or similar |
| CN101597875B (en) * | 2009-07-10 | 2014-06-18 | 南京林业大学 | New technique for improving paper strength by joint gelatinization of starch and pulp |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1110004A (en) * | 1964-07-28 | 1968-04-18 | Basf Ag | Improved papers having high mechanical strength and their production |
-
1983
- 1983-04-25 FI FI831400A patent/FI71379C/en not_active IP Right Cessation
-
1984
- 1984-04-04 DE DE19843412535 patent/DE3412535A1/en not_active Withdrawn
- 1984-04-17 CA CA000452222A patent/CA1232713A/en not_active Expired
- 1984-04-18 SE SE8402176A patent/SE460730B/en unknown
- 1984-04-24 NO NO841616A patent/NO163871B/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5876563A (en) * | 1994-06-01 | 1999-03-02 | Allied Colloids Limited | Manufacture of paper |
Also Published As
| Publication number | Publication date |
|---|---|
| NO163871B (en) | 1990-04-23 |
| FI71379B (en) | 1986-09-09 |
| SE8402176D0 (en) | 1984-04-18 |
| SE8402176L (en) | 1984-10-26 |
| FI831400L (en) | 1984-10-26 |
| DE3412535A1 (en) | 1984-10-25 |
| SE460730B (en) | 1989-11-13 |
| FI831400A0 (en) | 1983-04-25 |
| FI71379C (en) | 1986-12-19 |
| NO841616L (en) | 1984-10-26 |
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