Patent Application
20080035293
General Principle of Conducting DDJ Tests:
The stock used was composed of fibre samples from a paper mill, a filler and diluting water. The diluting water consisted principally of a clarified filtrate from the papermaking machine. The pH of the stock was regulated to the desired level.
The filler was treated in the form of a slurry with the desired amount of active ingredient to be examined before the filler was added to the stock. The doses are indicated as amounts of active ingredient of the dosed substance per dry matter weight of the filler, in units g/t (filler). The substance to be examined was added to the filler in the form of a diluted aqueous slurry.
Retention tests were conducted with a Dynamic Drainage Jar (DDJ) apparatus. The tests used the following step-wise procedure:
The wire was a DDJ wire 125P with 200 mesh apertures. The polymer was a cationic polyacrylamide from Kemira Chemicals, which is a copolymer of acrylamide and acryloyloxyethyltrimethyl ammonium chloride, and whose charge is approx. 1 meq/g and molecular weight 7 mg/mol (PAM1). The polymer doses are indicated as substance doses per dry matter weight of the stock, in units g/t.
The overall consistency of the pulps and filtered liquors was produced by filtering the solid matter separately and drying it in a heating chamber at a temperature of 100-105° C. The filler consistency of the stocks and the filtered liquors were obtained by burning the samples dried in a heating chamber at 525° C. for 3 hours.
Example 1 illustrates how a synthetic colloidal metal silicate, Laponite RD, acts with different fillers.
The tests were conducted as DDJ tests. The stock fibres consisted of bleached tall and birch pulps, which were used in the dry weight ratio 1:2. The fillers comprised
A clear filtrate from a fine paper machine up to a consistency of 10 g/l was used for diluting the stocks, followed by final dilution with ion-exchanged water to the test consistency.
The filler was treated with various amounts of the substance to be examined, which in this examples was a synthetic, colloidal metal silicate with magnesium as the predominant cation, sold under the trade name Laponite RD, manufacturer Laporte (nowadays Rockwood). Laponite RD has a particle size of approx. 25 nm and a specific area (BET) of approx. 400 m2/g.
A separate stock was prepared for each Laponite RD dosing level. The polymer (PAMI) dosage was 400 g/t. Laponite RD was added to the filler in the form of a 0.5% slurry. The tests are averages of two parallel tests.
The results of the tests with different fillers are collected in table 1.
This example clearly shows that both the filler retention and the overall retention are clearly improved with Laponite RD dosed along with the filler. In addition, as a rule, the greater the Laponite RD dose, the better retention.
Example 2 illustrates the activity of synthetic colloidal metal silicate, Laponite RD, with mechanical pulp included in the stock.
The tests were conducted as DDJ tests. Two different types of stock were used:
The higher pH stock contained peroxide-bleached thermomechanical pulp (TMP) and bleached tall pulp. The pulps were used in the dry weight ratio 4:1.
For stock dilution, a clear filtrate was taken from a neutrally (pH of about 7.5) running paper-making machine using mechanical pulp, by means of which the stock was diluted up to a consistency of 10 g/l, followed by final dilution with ion-exchanged water to the test consistency.
The lower pH stock contained dithionite-bleached thermomechanical pulp (TMP) and bleached tall pulp. These pulps were used in a dry matter ratio 4:1. For stock dilution, a clear filtrate was taken from an acidly (pH of about 5) running paper-making machine using mechanical pulp, by means of which the stock was diluted up to a consistency of 10 g/l, followed by final dilution with ion-exchanged water to the test consistency.
Both in the high and the low pH stock kaolin was used as a filler, which is sold under the trade name Intramax. It was treated with various amounts of substance to be examined, which, in this example, was a synthetic colloidal metal silicate having magnesium as the predominant cation, which is sold under the trade name Laponite RD, manufacturer Laporte (nowadays Rockwood).
A separate stock was prepared for each Laponite RD dosage level. The polymer (PAM1) dose was 400 g/t. Laponite RD was added to the filler in the form of a 0.5% slurry. The tests are mean values of two parallel tests.
The test results with different fillers are collected in table 2.
This example clearly shows that both the filler retention and the overall retention improved, although less distinctly than with fine paper pulp, with Laponite RD dosed along with the filler. In addition, as a rule, the higher the Laponite RD dose, the better retention.
Example 3 illustrates that colloidal silicas and silica particles of other types also act as a retention improving agent when the filler is treated with these before being added to the stock.
The tests were conducted as DDJ tests. The stock fibres consisted of bleached tall and birch pulps, which were used in the dry matter ratio 1:2. The filler consisted of pulverised calcium carbonate, GCC, sold under the trade name Mikhart 2, manufacturer Provencale S.A.
The stocks were diluted with a clear filtrate up to a consistency of 10 g/l from a fine paper machine, followed by final dilution with ion-exchanged water to the test consistency. The clear filtrate used originated from the same papermaking machine as the one in example 1, but taken at a different moment, so that the stocks had pH about 8.
The filler was treated with different amounts of substance to be examined, which in this example were
bentonite, the main component of which is montmorillonite, sold under the trade name Altonit SF, supplier Kemira Chemicals Oy, was added to the filler in the form of a 0.2% slurry. Altonit SF in dry state has a specific area (BET) of approx. 30 m2/g and of approx. 400 m2/g in wet state,
fumed silica, with the trade name Aerosil MOX 170, manufacturer Degussa, was added to the filler in the form of a 0.2% slurry. Aerosil MOX 170 has a particle size of approx. 15 nm and a specific area (BET) of approx. 170 m2/g,
structurised silica sol, with the trade name BMA 780, producer Akzo Nobel, was added to the filler as a 3% sol diluted to an active ingredient content of 8%. The particle size of BMA 780 is not exactly known, however, it is supposed to be less than 10 nm,
unstructurised silica sol, under the trade name Vinsil 515, producer Kemira Chemicals, Inc., was added to the filler as a 3% sol diluted to an active ingredient content of 15%. Vinsil 515 has a particle size of approx. 5 nm and a specific area of about 600 m2/g.
A separate stock was prepared for each dosing level. The polymer (PAM1) dosage was 400 g/t. The tests are mean values of two parallel tests.
The test results are collected in table 3.
This example clearly shows that both the filler retention and the overall retention improved with different colloidal silica or silicate-based particles dosed along with the filler. In addition, as a rule, the higher the particle dose, the better the retention.
Example 4 illustrates how various types of colloidal silica and silicate particles act as retention improving agents when the filler is treated with them before being added to the stock, even when the stock contains mechanical pulp.
The tests were conducted as DDJ tests.
The pulps consisted of peroxide-bleached thermomechanical pulp (TMP) and bleached tall pulp. These pulps were used in a dry weight ratio of 4:1. The filler was kaolin, sold under the trade name Intramax. For stock dilution, a clear filtrate was taken from a neutrally (pH of about 7.5) running paper-making machine using mechanical pulp, by means of which the stock was diluted up to a consistency of 10 g/l, followed by final dilution with ion-exchanged water to the test consistency.
The filler was treated with various amounts of the substance to be examined, which were the same in this example as those described in example 3.
A separate stock was prepared for each dosing level. The stock had pH 7.5. The polymer (PAM1) dosage was 400 g/t. The tests are mean values of two parallel tests.
The test results are collected in table 4.
This example clearly shows that both the filler retention and the overall retention improved with different colloidal silica or silicate-based particles dosed along with the filler, even when the stock contained mechanical pulp. In addition, as a rule, the higher the particle dose, the better the retention.
The example describes how Laponite RD metal silicate has retention improving action when the tests are conducted with a different test arrangement. In this arrangement, the second portion of a filler treated with colloidal silica and silicate particles is added to the stock containing the first portion of the filler.
The retention tests were conducted with a Moving Belt Former simulator. The stock consisted of stock fed to the headbox of a papermaking machine using mechanical pulp. The stock sample was taken just before the retention agent additions. The main components of the stock to be treated were thermomechanical pulp (TMP), tall pulp and fillers, of which kaolin formed the major portion. The stock consistency before additions was 12 g/l and the stock had a dry matter filler content of 56%.
Four different stocks were prepared. Four different titanium dioxide slurries were added to the stocks, increasing the stock consistency to 13.2 g/l. Two of the titanium dioxide slurries had been treated with Laponite RD in a dose of 4 kg/t (filler) and two had not been treated at all. The titanium dioxides were Kemira 920, producer Kemira Chemicals Oy, and Kemira RDE2, producer Kemira Chemicals Oy. These stocks were used in an amount of 333 g per test. The stocks had a pH value of approx. 5. The stocks are described in greater detail in table 5.
The vacuum level aimed at by passing air though a sheet was −25 kPa. The effective absorption period was 250 ms. The stock temperature during the tests was 50° C. The stirring rate was 2000 rpm. The polymers were dosed 10 s before filtering of the web. The conditioned basis weight of the sheets was measured and used for calculating the overall retention.
The test used as polymers PAM1 and PAM2, which is a cationic polyacrylamide having a charge of about 2 meq/g and a molecular weight of about 5 Mg/mol, manufacturer Kemira Chemicals Oy.
The results are given in table 5.
The tests show that each time titanium dioxide has contained Laponite RD, the sheet has formed with a higher basis weight, although the stock dose has remained the same in all of the tests. This is due to the fact that Laponite RD has enhanced the retention of the fillers, also of those previously contained in the stock. It is remarkable that Laponite RD has enhanced the retention also in cases where no retention polymer has been used (comparative tests 7 and 8 and 15 and 16, respectively).
A comparison of tests 4-6 of the example allows the evaluation that a retention level of 58.4%, which is achieved with a PAM1 dosage of 400 g/t when Kemira 920 has not been treated with Laponite RD, is achieved with a PAM1 dosage of about 270 g/t, when Kemira 920 has been treated with Laponite RD. Accordingly, a comparison of tests 12-14 allows the evaluation that the same retention level of 61.5%, which is achieved with a PAM1 dosage of 400 g/t when Kemira RDE2 has not been treated with Laponite RD, is achieved with a PAM1 dosage of about 350 g/t when Kemira RDE2 has been treated with Laponite RD.
Sheets in which the titanium dioxide content of ash was determined after ashing by an X-ray fluorescence method showed a higher titanium dioxide content in the ash each time the titanium dioxide had contained Laponite RD. This also indicates the improving effect of Laponite RD on titanium dioxide retention.
The example describes how Laponite RD metal silicate has an improving effect on both retention and optical efficiency.
The tests were conducted with a Moving Belt Former simulator using the running parameters described in example 5. However, in this case, the stock was composed of machine tank pulp taken from a papermaking machine using mechanical pulp and having a filler content of approx. 25% and of a clear filtrate from the same papermaking machine. Fillers used by the same paper-making machine were added to the pulp, with the main portion being kaolin, and titanium dioxide, Kemira 920, and calcinated kaolin taken from the same paper-making machine, the final filler content of the stock dry matter being approx. 55%, about 7.5% units of which was calcinated kaolin and about 7.5% unit was titanium dioxide.
Titanium dioxide and calcinated kaolin were mixed together as slurries 30 min before they were added to the stock. Two stocks were prepared, with one containing titanium dioxide, to which 4 kg/t (filler) of Laponite RD had been added, and with no Laponite RD addition at all to the other one.
After the filler addition, the stock consistency was 13.2 g/l, which was diluted to operation consistency of about 10 g/l using tap water. The stocks had a pH value of about 6. The polymer was PAM2.
The results are given in table 6.
Primarily, the results still show that the same polymer dosage yields a heavier sheet when the titanium dioxide had been treated with Laponite RD. This is due to the improving effect of Laponite RD on filler retention. Examination of the sheets further shows that the same basis weight level yields higher sheet brightness when the titanium dioxide had been treated with Laponite RD. This is due to higher titanium dioxide retention to the sheet under the effect of Laponite RD.
Example 7 describes how a synthetic colloidal metal silicate, Laponite RD, has an improving action on filler retention even when no retention agent is used at all.
The tests were conducted as DDJ tests according to the general principle, however, without using any retention polymer at all. The stock fibres were bleached tall and birch pulp, which were used in the dry weight ratio 1:2. The fillers were pulverised calcium carbonate, GCC, with the trade name Mikhart 2, producer Provencale S.A. For stock dilution, a clear filtrate was taken from a fine paper machine up to a consistency of 10 g/l, followed by final dilution with ion-exchanged water to the test consistency.
The tests were conducted with two stocks that were otherwise identical, except that the filler of one stock was pre-treated with the examined substance before the filler was added to the stock. The filler was treated with synthetic colloidal metal silicate, with magnesium as the predominant cation, sold under the trade name Laponite RD, producer Laporte (nowadays Rockwood). Laponite RD has a particle size of about 25 nm and a specific area (BET) of about 400 m2/g. Laponite RD was used in an amount of 3 kg/t (filler).
The test results with different fillers are collected in table 7. The test results are mean values of two parallel tests.
This example clearly indicates that both filler retention and overall retention were distinctly improved with Laponite RD dosed along with the filler, although the tests did not use any retention polymer at all.
Example 8 is a comparison between the use of microparticles in accordance with the invention and in accordance with prior art.
The tests were conducted as DDJ tests according to the general principle, however, with the following dosage used as the dosage sequence:
1. At moment 0 s with a stirring rate of 1,500 rpm a stock sample (500 ml) was poured into a vessel.
2. At moment 10 s a chemical ANN1 was dosed into the stock.
3. At moment 35 s a chemical ANN2 was dosed into the stock.
4. At moment 45 s a filtrate sample of 100 ml was collected.
In the prior art procedure, the microparticle was added to the stock at dose position ANN2 as a 0.4% slurry.
The stock fibres consisted of bleached tall and birch pulp, which were used in the dry weight ratio 1:2. The fillers were pulverised calcium carbonate, GCC, with the trade name Mikhart 2, producer Provencale S.A.
For stock dilution, a clear filtrate was taken from a fine paper machine up to a consistency of 10 g/l, followed by final dilution with ion-exchanged water to the test consistency.
The tests were conducted with two stocks that were otherwise identical, except that the filler of one stock was pre-treated with the examined substance before the filler was added to the stock. The filler was treated with synthetic colloidal metal silicate, with magnesium as the predominant cation, sold under the trade name Laponite RD, producer Laporte (nowadays Rockwood). Laponite RD has a particle size of about 25 nm and a specific area (BET) of about 400 m2/g. Laponite RD was used in an amount of 3 kg/t (filler).
The test results with two ways of using microparticles are collected in table 8. The test results are mean values of two parallel tests.
When the results of tests with the same amounts of retention polymer are mutually compared, this example clearly shows that the use of the microparticle Laponite RD in accordance with the invention is more advantageous than the prior art procedure.
Example 9 is a comparison between the use of microparticles in accordance with the invention and in accordance with prior art. The example used a different microparticle from that of example 8.
The tests were conducted as DDJ tests as in example 8, however, the microparticle in the prior art procedure was bentonite, whose major component is montmorilloinite, with the trade name Altonit SF, supplier Kemira Chemicals Oy. Altonit SF in dry state has a specific area (BET) of about 30 m2/g, and of about 400 m2/g in wet state.
In the prior art procedure, the microparticle was added to the stock at the dose location ANN2 as a 0.5% slurry.
The test results are collected in table 9. The test results are mean values of two parallel tests.
This example also clearly shows that the use of microparticles in accordance with the invention is the more advantageous of the two procedures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20030568 | Apr 2003 | FI | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FI04/00229 | 4/14/2004 | WO | 00 | 3/21/2007 |
