JPH06184977A - Method for treating of fiber for paper manufacturing for manufacturing tissue - Google Patents

Abstract

PURPOSE: To markedly enhance the throughdryability of paper produced from papermaking fibers under condition dewatered, but wet, by subjecting an aq. suspension of fibers at high consistency to elevated temp. with sufficient working of the fibers. CONSTITUTION: A method of tissue making is constituted by a step forming an aq. suspension consisted of papermaking fibers having a concn. of more than about 20%, a step passing the prescribed aq. suspension at >=75 deg.F through a shaft grinding machine inputing power of about 1 horsepower/day per dried fibers of 1 ton and the prescribed step increasing TD index of the prescribed fibers of more than about 25%, a step supplying the prescribed fibers via a tissue making head box to form wet-web, and a step drying the prescribed web to form dry tissue.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a method of treating papermaking fibers for making tissue.

[0002]

BACKGROUND OF THE INVENTION When making certain paper products, such as tissues and paper towels, one method of drying the paper after molding and dehydration is to heat it in a process commonly known as through-air drying in papermaking technology. The passing of air through the wet paper. Through-air drying minimizes compression of the web, which can result in a more bulky product, so a conventional wet press that compresses a wet web at a high level and then dries this web on a Yankee dryer. It is advantageous compared to the manufacturing process. However, through-drying has some drawbacks in that it requires fairly large scale and expensive equipment and energy to carry out the drying process.

[0003]

In particular, the drying efficiency of the through-air drying process is primarily determined by the air permeability of the hot paper which allows hot air to pass through the paper. Air permeability is particularly problematic for papers made from fiber raw materials containing secondary (recycled) fibers, which means that the air permeability for wet papers containing these secondary fibers is This is because the fiber essentially makes it worse. As environmental efforts continue to make greater use of secondary fibers in paper products for environmental reasons, there is a need to improve the through-drying properties of secondary papermaking fibers.

[0004]

Surprisingly, it has been discovered that pretreatment of the fibers of the papermaking raw material by a mechanical process greatly facilitates the through-drying of secondary papermaking fibers. In this case, the fibers are allowed to act appropriately while being suspended in the concentrated aqueous slurry. The effect of this pretreatment is manifested by an increase in the through-drying index of these fibers (hereinafter defined as the "TD index" and thus referred to). As the TD index increases, the speed of the through-air dryer for a given raw material and basis weight can be increased, resulting in improved operating efficiency. The method of the present invention can be used for all papermaking fibers, but is particularly advantageous for improving the TD index of secondary fiber raw materials. In some cases, the TD index of the secondary fiber feedstock can be surprisingly improved over that of the untreated virgin feedstock.

Further, while the fiber treatment of the present invention is particularly advantageous for through-drying processes and products, it is also useful when treating the fibers treated according to the present invention to produce wet pressed tissue products. Product improvements can be realized as well. More specifically, when some of the fibers of a given tissue material are replaced with the fibers treated according to the invention, the resulting tissue has
Softness can be increased without losing strength. This is particularly useful when treating hardwood fibers and combining the treated hardwood fibers with other fibers such as untreated softwood fibers that have been blended or layered. Treated hardwood fibers improve the flexibility of the resulting product, while untreated softwood fibers retain their strength. The softness can be further increased by adding a softening agent to the treated fiber before or after the treatment. Some kind of softener
There is an unexpected increase in bulk and tissue softness.

Accordingly, in one aspect, the present invention comprises:
(A) forming an aqueous suspension of papermaking fibers having a concentration (dry weight percent of fibers in the aqueous suspension) of about 20% or greater; (b) adding the aqueous suspension to a temperature of 75 Passing at least about 1 hp-day of power per ton of dry fiber above ° F to a shaft disintegrator with an input of T of said fiber.
The above step wherein the D index is increased by about 25% or more, preferably about 50% or more, more preferably about 75% or more,
(C) feeding the fibers through a tissue manufacturing headbox to form a wet web, and (d) drying the web by air drying or the like to form a dry tissue. Is the way.

In another aspect, the invention comprises (a) about 20%.
Forming an aqueous suspension of papermaking fibers having the above concentration, (b) adding the aqueous suspension to a temperature of 75
At least about 1 per ton of dry fiber above ° F
A step of passing horsepower-day power through a shaft disintegrator, wherein said fiber has a TD index of about 0.15 or more, preferably about 0.2 or more, more preferably about 0.3 or more, Most preferably about 0.5 or above, (c) feeding the fibers through a tissue making headbox to form a wet web, and (d) air drying the web. The method comprises the steps of drying to form a dry tissue.

In yet another aspect, the invention comprises at least 2
It is a through-dried paper produced from a raw material composed of 5% by dry weight of secondary fiber, wherein the raw material is about 0.
It has a TD index of 15 or more, preferably about 0.20 or more, more preferably about 0.33 or more, and most preferably about 0.5 or more. The amount of secondary fiber in this raw material is about 2
Any in the range of 5 to about 50% by dry weight, or 1
00% by dry weight.

Papermaking fibers useful for the purposes of the present invention include all cellulosic fibers known to be useful in making paper, particularly face tissue, bath tissue, dinner. Tissues with relatively low density such as napkins, paper towels, etc.
Fibers useful for making paper are included.
As used herein, the term "tissue" is used in a generic sense and is intended to encompass all such products. The most common papermaking fibers include virgin softwood and hardwood fibers and secondary or recycled cellulose fibers. As used here,
A "secondary fiber" is previously separated from its initial matrix by physical, chemical or mechanical means,
Also meant are all cellulosic fibers which have been further formed into a fiber web, dried to a water content of about 10% by weight and subsequently separated again from the matrix of the web by some physical, chemical or mechanical means. To do. Fibers that have passed through a shaft disintegrator, as described herein, are referred to as "disintegration fibers".

The air-dried paper has a basis weight of about 5 to about 50.
g / m ² , preferably about 10 to about 40 g / m ² , and more preferably about 20 to about 30 g / m ² . It can be seen that low basis weight papers have essentially greater breathability for a given raw material. Therefore, the greatest advantage of the present invention is obtained at relatively high basis weights, where it is more difficult to air dry ordinary paper. The present invention is most suitable for producing a through-dried single layer bath tissue having a basis weight of about 25 g / m ² .

The concentration of the aqueous suspension to be treated according to the present invention must be sufficiently thick to bring the fibers into sufficient contact or action to alter the surface properties of the treated fibers. I won't. In particular, this concentration is at least 20% by dry weight, more particularly about 20 to about 60% by dry weight, and most preferably about 30 to about 50% by dry weight. This concentration depends primarily on the type of machine used to process these fibers. For example, in the case of some rotary shaft disintegrators, concentrations above about 40% by dry weight risk clogging the machine. Bivis machine (Cl
external Company, Firmy Ce
In the case of other types of disintegrators, such as dex, commercially available from France), concentrations of 50% by dry weight or more can be used without clogging. When using a particular machine, it is preferable to use the highest concentration possible.

The fiber temperature is room temperature, especially 75 ° F.
More preferably, it is 100 ° F or higher, preferably 150 ° F or higher, more preferably 210 ° F or higher, and even more preferably about 220 ° F or higher. Higher temperatures are generally preferred to increase the TD index. The upper temperature limit depends on whether the device is pressurized, because the aqueous fiber suspension in the device operating at atmospheric pressure cannot be heated above the boiling point of water.

The amount of power applied to the suspension of fibers adds impact to the resulting TD index. Generally, increasing the power input increases the TD index. However, the power input to the dry fibers in suspension is about 2 hp-ton / ton (HPD / T)
It has also been found that the improvement (increase) in the TD index decreases when the temperature reaches 0. The preferred range of power input is about 1 to 3 HPD / T, more preferably about 2 HPD / T or more.

It is not known that the action of fibers due to shear or compression is measurable in any sense other than temperature and power input and the resulting TD index. However, the fibers substantially experience rubbing or shearing of the fibers with each other and contact by rubbing or shearing with the surface of the mechanical device used to treat these fibers. You need to experience what to do. Some compression, which means pressing the fiber against the fiber itself, is also preferred to enhance and enhance the effect of rubbing or shearing of the fiber. The determination of the proper amount of shear and compression to be used depends on the final result, ie how much the increase in the TD index has been achieved. Numerous shaft disintegrators or equivalent mechanical devices well known in the paper industry can be used to achieve varying degrees of desired results. Suitable shaft disintegrators include
Without limitation, non-pressurized shaft disintegrators such as Bivis machines and pressurized disintegrators are included.

If softeners are used to increase the softness of the final tissue product, suitable softeners include, without limitation, fatty acids, waxes, quaternary ammonium salts, dimethyl dihydrogenated tallow ammonium chloride ( dimethy
l dihydrogenated tallow a
mmmonium chloride), quaternary ammonium methylsulfate, carboxylated polyethylene, cocaamide diethanol amine (cocamide die)
tanol amine), coco betaine (coc
o betaine), sodium lauroyl sarcosi
nate), a partially ethoxylated quaternary ammonium salt,
Includes distearyl and dimethyl ammonium chloride. Suitable commercially available chemical softeners include, without limitation, Eka Nobel Inc. Made Bero
cells 564 and 584, S Shearex Chem
Adengen 442, Q manufactured by ical company
Q made by raker Chemical Company
qsoft203, and Akzo Chemical
Includes Arquad 2HT-75 from Company.

[0016]

【Example】

Flow-Drying Index During drying, it is generally understood that the higher the water content, the faster and relatively constant the drying rate (constant rate period). After the paper reaches a certain critical water content, the drying rate begins to decrease fairly rapidly (reduction rate period). It is believed that if the air permeability remains constant throughout the drying period, the pressure drop will also decrease as the water content decreases (or as the drying process continues). How the pressure drop changes during the through-drying process when the air permeability is constant is a major concern for the purposes of the present invention, because of this:
This is because it provides a quantitative means for measuring the air permeability of paper during drying. If it is possible to accurately measure the instantaneous absolute humidity of the outlet air after drying a tissue sample, calculate the instantaneous moisture content from this outlet air humidity and the initial and final moisture content of the tissue sample as follows: be able to.

[0017]

[Equation 1] Where "X ₀ ": water content of the test sample at the start of the test expressed in Kg of water per 1 kg of absolute dry fiber; "X _end ": test expressed in Kg of water per 1 Kg of absolute dry fiber Moisture content of the test sample at the end of the step; "X _m ": Instantaneous water content of the test sample expressed in Kg of water per Kg of absolute dry fiber; "Y _in ": Kg of water per Kg of dry air Humidity of dry air immediately before reaching the sample shown; "Y _out t": Humidity of dry air immediately after passing through the sample, expressed in Kg of moisture per 1 kg of dry air; "t": Progress in seconds Time Moisture content X from the humidity data for the entire drying period
_{Once m} is calculated, the pressure drop can be plotted as a function of instantaneous water content. The reciprocal of the area at the bottom of the resulting curve is called the TD index, and is known as the kilopascal- ^1.
Express as. This index is a measure of the air permeability of wet paper and represents how easily paper made from a particular raw material can be through-dried. A higher value of the TD index indicates easier through-air drying, and a lower value of the TD index indicates more difficult through-air drying.

As will be explained below, the measurement of the TD index requires that the fiber in question be formed into a test handsheet with a basis weight of 24 g / m ² . This is a sample of fiber in water in a British pulp disintegrator at 2.5
It is achieved by dipping to a concentration of wt% and soaking the dispersed sample for 5 minutes. The sample is then pulped at ambient temperature for 10 minutes, diluted to a concentration of 0.04% and formed into test handsheets with a British test handsheet mold (Herman, Lancaster, OH). This test handsheet, without applying pressure,
Clot from the mold by hand using a blotter. This test handsheet uses a Valley steam plate and a standard weight canvas cover with a lead-filled (4.75 lb) brass tube at one end to maintain uniform tension. Dry for about 2 minutes to absolute dryness. The TD index of the resulting dried test handsheet is then determined as described herein and the measured TD index value is assigned to the Her fiber or raw material from which the test handsheet was made.

Now, the apparatus for obtaining the TD index will be described in detail with reference to FIG. Unless otherwise specified, the main airflow tubing has an inner diameter of 1.5 inches. The air drying these samples was supplied by two "unlubricated" compressors 1, each of these compressors being rated at 90p.
It is 29.9 cf ³ per minute for si (model DN 102
4H-3DF, Atlas Compressor, Cleveland, Ohio). The outlets of these compressors are
Appropriately connected to the inlet of Condensate Separator 2 (Model WSO-08-000, Wilkerson, Englewood, CO), this separator has the function of removing all water contained in the air stream. Fulfill The outlet of this separator is suitably connected to the inlet of a molecular sieve 3 (Model M530, Wilkerson), which removes particulate matter in the air with particles above about 0.05 micron in size. Fulfill the function of The outlet of this molecular sieve is a compressed air dryer 4 (Wilkerson model DHA-AE-00).
0), the outlet of this dryer is 49c / min
It has a flow rate of f ³ . The outlet of this dryer is connected to the inlet of the surge tank 5 (capacity of about 75 cf ³ ). The outlet of this surge tank has two separate oil heat exchangers 6
And 7 (capacity 5 liters / maximum temperature 250 ° C / maximum pressure 6
Barb, Apparatebau Wiesloch
Appropriately connected in series to GmbH, Wiesloch, Germany), these heat exchangers further heat the air to the desired aeration drying temperature. Between the surge tank and the two heat exchangers, a humidity monitoring device 8 (Aquanel,
Gerhard GmbH, Blankebach, G
, gate-type control valve 9 (DIN R65, 1.5 inch, PN16, Hen) for controlling the flow velocity of air
ose, Hamburg, Germany), orifice plate 10 (25 mm diameter opening, RST37)
-2 PN6 DIN2527-32-5784, Un
versity of Karlsruhe, Kar
lsruhe, Germany), and manometer 11
(Betz, Gottingen, Germany) are provided and used together to determine the air velocity. Other valves and tubing (not shown), which are not essential to the operation of this device, may be conveniently provided at various locations to disconnect or bypass the gauge and other devices. The outlet of the second heat exchanger is directly connected to the sample housing 12, which has a slidable sample tray 13 (see FIG. 2) having a sample holder (see FIG. 2) mounted therein. Designed to receive and hold. All air passes through the sample mounted in this sample holder. An inflatable gasket mounted within the sample housing can ensure a secure seal between the sample housing and the slidable sample tray if the gasket were to function. An air diffuser 14 is suitably connected to the outlet of the sample housing, so that the cross section of the air flow is reduced to reduce the velocity of the air flow to allow more accurate humidity measurements. Extend to 600 mm2. This air diffuser is suitably connected to a vent pipe that conveys air to a suitable exhaust system. Differential temperature sensor 16
(Resistance type differential) is connected appropriately and the temperature of the air before and after the sample is measured. Differential pressure sensor 17 (PU100
The pressure drop across this sample is measured with an appropriate connection of 0, 0-1000 mbar, 110 VAC. Higher sensitivity second humidity monitoring device 18 (infrared; 25 per second
Measurements; Manufacturer: Paderborn Univers
, Paderborn, Germany) measures the water content of the air exiting this sample. All three of these sensors are connected to Schlumberger's data collection system 19, which uses a computer 20 (RMC) to send this data back.
80286 processor).

FIG. 2 shows a sample holder and a method of mounting the sample in the sample holder, the sample holder holding and sliding the sample holder in and out of the sample housing. It has a sample tray 13. FIG. 2 shows the upper part of the sample holder 21, that is, the upstream part and the sample holder.
This is the lower portion, that is, the downstream portion of the holder 22. This sample
The lower portion of the holder includes support cloth 23 (Asten 937, Asten, Appleton, Wisconsin),
The sample is placed on this. A sample 24 of test handsheet is sandwiched between the upper and lower portions, which is cut to size. When the sample is fixed by grease (not visible in this figure) applied in a thin line around the inner edge of the top of the sample holder, a seal is created between the sample and the top of the sample holder. Two locating pins 25 on top of sample holder
And these pins are inserted into the lower locating holes 26 of the sample holder and these two halves are fixed by six screws 27 with suitable screw holes.

Now that the apparatus for determining the TD index has been clarified, the procedure for determining this TD index can be described. Generally, a given test sample (24 g / m ²
To obtain the TD index of the test handsheet, the sample was carefully wetted to a specific moisture level and the sample was prepared in the above described apparatus under controlled conditions to have a constant air mass flow rate. dry. The moisture level in the sample is continuously calculated by the computer based on the measured air humidity before and after the sample under test. Plotting the pressure drop measured before and after this sample as a function of calculated moisture level for this sample, the area under the curve is the TD index.

More particularly, the test handsheet sample to be tested is cut into a circle with a diameter of 10.25 cm, which fits into the sample holder of the device and the opening of the sample holder. Slightly larger than. During the test, only circular samples with a diameter of 10 cm are exposed to the air flow. Therefore, the portion of the circular sample outside the sample holder opening is impregnated with grease (Compound 3 valve lubricant and sealant, Dow Corning, Inc., Midland, MI) before wetting for testing. However, this is to prevent all water from seeping out of the circular section and to provide a more secure seal between the sample and the sample holder.
This is done by applying grease and rubbing around the inner edge of the upper half (upstream half) of the sample holder. The sample is then placed in the lower half of the sample holder with a piece of air-drying cloth (Asten 937) to support it. Then clamp it to the upper half sample holder and the lower half sample holder,
The outer edge of this sample is impregnated with grease. Then, until the moisture level of the completely dried fiber reaches the level of 3.0 kg per kilogram of this fiber,
Wet this supported sample by spraying with a fine mist. During spraying, the cover guard must be placed over the entire surface of the sample holder to prevent spraying of the sample holder and to direct all sprayed water into a circle with a diameter of 10 cm. The water content of this sample is
Accurately measure the difference in weight before and after wetting.

During preparation of the sample, the air system is operated at a predetermined constant flow rate of 3.0 Kg per square meter per second and is heated to a temperature of 175 ° C. When the steady state is reached, the temperature of the air becomes stable and constant,
Humidity is zero and pressure drop is zero. When the reference steady state conditions are reached, the sample holder containing the wet test sample is placed in the slidable sample tray and slid into the sample housing of the instrument. Humidity and pressure drop are constantly monitored by instruments and computers, which gives a plot of pressure drop versus water content. A representative plot is shown in FIG. (In this plot, time increases from right to left.) As shown, the pressure drop initially increases at a very fast rate and then begins to decrease rapidly, typically at a constant level in 4 or 5 seconds. To reach. The computer then sums the reciprocal areas under the curve and calculates the TD index as previously described.

FIG. 4 illustrates the steps of the overall process of treating a fiber according to the present invention. Shown in the figure is a high-concentration pulper 29 (models ST6C-W, B for processing).
old Escher Wyss, Mansfield
d, MA), and the dilution water 30 is added to this to make a concentration of about 15%. The stock is diluted to a concentration of about 6% before being pumped out of the pulper. The pulped fiber was then scalped screen 31 (Fiber Riser Model FT-E, Bird Escher Wys) with additional dilution water to remove large contaminants.
s company). The density entering this scalping screen is about 4%. What is caught by this scalping screen is supplied to the exhaust gas treatment device 32. After passing through this scalping screen, the high-density cleaner 33 (Cyclone type, size; 7 inches,
Bird Escher Wyss) to remove heavy contaminants that could not be captured by the scalping screen. What is caught by the high-density cleaner is supplied to the exhaust gas treatment device. The one that passed through the high-density cleaner is the fine screen 34A (Centresorter, Model 20).
0, Bird Escher Wyss) to further remove smaller contaminants. Dilution water is added to the fine screen feed stream to achieve a feed concentration of about 2%. What is caught on this fine screen is the second fine screen 34B (Axiguard, Model 1, B).
ird Escher Wyss) to remove other contaminants. Those that have passed through this are recycled into the supply flow toward the fine screen 34A, and those that have not passed through are supplied to the exhaust gas treatment device. After passing through this fine screen, dilution water was added to a concentration of about 1%, then a series of four flotation cells 35, 36,
37 and 38 (aerator, model CF1, Bird
Escher Wyss) to remove ink particles and sticky substances. Those caught in each of the flotation cells are supplied to the exhaust gas treatment device. The washer 39 (Double Nip Thickener, Model 100, BlackClawso) that passed through the last-stage floating cell
n, Middledown, OH) to remove very fine ink particles and increase the density to about 10%. What is caught by this washer is supplied to the exhaust gas treatment device. What passed this washer was a belt press 40 (Alas-Andritz belt fiber press, model CPF, 20 inch, Andr.
itz Ruthner, Arlington, TX)
To reduce the water content to about 30%. The pressed product is supplied to the exhaust gas treatment device. The resulting partially dehydrated fibrous material was then passed through a shaft disintegrator 41 (GR II, Ing. S. Maule &
C, S. p. A. , Torino, Italy), which are described in detail in FIG. 5 and act on these fibers to increase the TD index in accordance with the present invention. Steam 42 is added to the disintegrator feed stream to raise the temperature of the feed material. The resulting treated fibers 43 can be used directly as feedstock for papermaking, or otherwise processed further as desired.

FIG. 5 is a cutaway perspective view of a preferred apparatus for treating fibers according to the present invention as shown in FIG. This particular device is described by Ing. S. Maur &
C, S. p. A. Model GRII, a shaft disintegrator manufactured by Torino, Italy. Shown are an upper cylindrical housing 51 and a lower cylindrical housing 52, which when closed enclose a rotating shaft 53 having a plurality of arms 54. The upper housing is 2
It has rows of knurled fingers 55 and three inspection ports 56. An inlet port 57 is provided at one end of the upper housing. A drive motor 58 for rotating the rotating shaft is provided at the entrance end of the rotating shaft. A bearing housing 59 is provided at the outlet end of the rotary shaft to support the rotary shaft. A screw feed section 60 is provided at the inlet end of the rotating shaft, which is located directly below the inlet and serves to force the feedstock through the disintegrator. The outlet 61 of this crusher is constituted by a hinged flap 62 with a lever 63, which is
When the crusher is closed, it engages the hydraulic air bag 63 mounted on the upper housing. The air bag provides controllable resistance to rotation of the hinged flap, thus providing a means of controlling back pressure in the crusher. Increasing this back pressure increases the extent to which the fiber acts, thereby increasing the TD index. In operation, the knurled fingers engage the arms of the rotating shaft to act on the feedstock therebetween.

FIG. 6 is a block diagram of another process of the present invention using a pair of Bivis machines.
Screw the papermaking pulp, which is preferably a secondary fiber pulp, having a concentration of about 50%, as shown.
Supply to the feeder. The screw feeder weighs and stocks the feedstock first of the two Bivis machines connected in series. Each Bivis machine has three compression / expansion zones. Inject the above into the 1st Bivis machine and keep the fiber temperature about 2
Raise to 12 ° F. The treated pulp is fed to a second Bivis machine operating under the same conditions as the first Bivis machine. The treated pulp from the second machine can be quenched by dropping it into a bath of cold water and then dehydrated to the appropriate consistency. Illustrative Having described the TD index and a method of practicing the invention, the invention will now be described in further detail with reference to the following examples. Example 1 Secondary fiber (office paper discharge grade) was treated in the process described in FIG. In particular, the secondary fiber is repulped at a concentration of 15%, cleaned and
Pressed to a density of 2.9% and then Ma as shown in FIG.
It was supplied to the ule shaft disintegrator. This crusher
A temperature of 175 ° F was maintained. The power input to the disintegrator was approximately 1.39 hp-day / ton of fiber (HPD / T). Samples before and after crushing were taken out and dried to 24 g / m ² test handsheet sheets were obtained by the method previously described. T
The D-index measurement was performed as previously described. The results are shown in Table 1 below. (“TD” is an index of air-drying property expressed as kilopascal-1. “Tension”
Is expressed in grams per inch of sample width. "Tear strength" is the Hermendorf tear strength in grams-force per 4 sheets of paper. "Caliper" is the thickness in inches. "TEA" is gram-centimeter / c
It is the absorbed tensile energy represented by m ² . ) Table 1 Sample TD Tensile strength Break strength Before crusher 0.11 1274 18.0 After crusher 0.30 739 17.2 Table 1 (continued) Sample caliper TEA Before crusher 0.00588 After the crusher 0.0076 3.8 Example 2 The temperature of the crusher was 175 ° F, the concentration before applying the crusher was 34.7%, and the power input to the crusher was 2.12HPD. /
Example 1 with the same secondary fiber material, but with T
Processed as described above. Samples before and after being placed in the disintegrator were removed and molded into test handsheets as previously described. These results are shown in Table 2.
Shown in. Table 2 Sample TD Tensile strength Breaking strength Before crusher 0.12 1278 18.0 After crusher 0.53 585 14.0 Table 2 (continued) Sample caliper TEA Before crusher 0.0060 6. 6 After crusher 0.0082 2.5 Example 3 Temperature of crusher is 150 ° F, concentration before crusher is 34.6%, power input to crusher is 2.15HPD /
Example 1 with the same secondary fiber material, but with T
Processed as described above. Samples before and after being placed in the disintegrator were removed and molded into test handsheets as previously described. These results are shown in Table 3.
Shown in. Table 3 Sample TD Tensile strength Breaking strength Before crusher 0.14 1334 19.2 After crusher 0.37 884 18.0 Table 3 (continued) Sample caliper TEA Before crusher 0.0060 7. 9 After the crusher 0.0070 4.9 Example 4 The temperature of the crusher was 81 ° F, and the concentration before applying the crusher was 2
6.8%, power input to the disintegrator is 2.44 HPD / T
The same secondary fiber material was treated as described in Example 1, except that Samples before and after being placed in the disintegrator were removed and molded into test handsheets as previously described. The results are shown in Table 4.

Table 4 Sample TD Tensile Strength Breaking Strength Before Crusher 0.10 1409 19.6 After Crusher 0.17 1125 20.0 Table 4 (continued) Sample Caliper TEA Before Crusher 0. 8.3 After the crusher 0.0062 6.7 Example 5 The temperature of the crusher was 79 ° F, and the concentration before applying the crusher was 3
4.6%, power input to the crusher is 1.18HPD / T
The same secondary fiber material was treated as described in Example 1, except that Samples before and after being placed in the disintegrator were removed and molded into test handsheets as previously described. The results are shown in Table 5.

Table 5 Sample TD Tensile Strength Breaking Strength Before Crusher 0.10 1322-After Crusher 0.14 1189 22.4 Table 5 (continued) Sample Caliper TEA Before Crusher 0.0055 5 After the crusher 0.0060 6.7 Example 6 The temperature of the crusher is 78 ° F, and the concentration before the crusher is 3
7.1%, power input to the crusher is 2.95 HPD / T
The same secondary fiber material was treated as described in Example 1, except that Samples before and after being placed in the disintegrator were removed and molded into test handsheets as previously described. The results are shown in Table 6.

Table 6 Sample TD Tensile Strength Breaking Strength Before Crusher 0.10 1435 20.0 After Crusher 0.19 1155 21.6 Table 6 (Continued) Sample Caliper TEA Before Crusher 0. 8.1 After the crusher 0.0064 6.1 Example 7 A well-washed secondary fiber with a concentration of about 50% in small pieces was screwed into a Bivis machine (Clextral Co., Pharmini Seedex, France). -Supplied through the feeder as shown in Fig. 6. This Bivis refiner is a twin-screw refining mechanism with a machined internal compartment, which is equipped with screws so that the scraper parts of the screws on both shafts come close to each other. Located. Steam is introduced into this internal compartment to raise the temperature of the pulp to about 105 ° C. As the pulp was fed to the Bivis machine, the screws rotated in the same direction and the scraper section was angled to force the pulp to move across the long axis of the device. Along the screw shaft, the directions of these scraper parts were periodically reversed. The direction of these scrapers forces the pulp to reverse its direction of movement, resulting in back pressure. These inverted scraper parts have small grooves machined into them,
The resulting pressure forces the pulp through these channels. The high compression / expansion action of the scraper part of the reversed screw, in combination with the friction between the fibers caused by the high density of the pulp and the close proximity of the scraper part of the adjacent screw shaft, exerts a high degree of action on the fibers. Was given. The product obtained from the first Bivis machine is the second product that operates under the same conditions.
Sent to the Bivis machine. From this second Bivis machine, the pulp was sent to a 10 ° C. quench tank. The pulp was then dewatered by gravity to produce the final product. The pulp thus treated was processed into a 24 g / m ² hand sheet as previously described and the TD index was determined as previously described. The results are shown in Table 7. Table 7 TD Tensile Strength Breaking Strength Before Bivis Machine 0.08 1072 18.5 After Bivis Machine 0.71 388 10.5 Table 7 (Continued) Caliper TEA Before Bivis Machine. 0061 5.65 After the Bivis machine. 1.28 1.28 The results obtained from the above examples show that the through-drying index of secondary fibers can be significantly increased by applying high density processing power to these fibers in a disintegrator. (And thus can improve the through-drying behavior of these fibers). It also improves the tissue-manufacturing properties of these fibers by increasing the bulk and reducing the tensile and breaking forces by applying a high density processing force. Example 8 1 cenibra eucalyptus fiber
It was pulped at 0% consistency for 15 minutes and dehydrated to 30% consistency. Softener [Berocell 584]
Was added in an amount of 10 pounds per ton of dry fiber and the pulp was then fed to a Maure shaft disintegrator as shown in FIG. This crusher has 2.2 HP
The power of D / T was input and it was operated at 160 ° F.

The resulting disintegrated eucalyptus fiber was processed into a two-ply tissue having a softwood fiber layer and a eucalyptus fiber layer. Prior to formation, Northern Craft Softwood Fiber (LongLac-19) was pulped at 4% consistency for 60 minutes, while crushed eucalyptus fiber was 4%.
Was pulped for 2 minutes at the above concentration. 0.05 for each layer
Formed on a separate forming fabric at a concentration of about 50% at a rate of about 50 feet per minute and the resulting two webs were cooed together at a concentration of about 10% to form a two layer web. The resulting layered web was conveyed to a papermaking felt and then pressed against the surface of a Yankee dryer where it was dried and creep processed at a creep ratio of 1.3. The dryer side of this layered web is composed entirely of softwood fibers, 2.7
It had a basis weight of 5 lb / 2880 ft ² (dryer basis weight). The air side of this layered web was composed of all of the same basis weight of disintegrated eucalyptus fibers. After creeping, the tissue was wound on a bath roll with minimal pull.

The resulting tissue has a tensile force =
858g / 3 inch width (machine direction) and 488g / 3 inch width (machine direction), elongation = 30.4% (machine direction) and 5.8% (machine direction), and by judge Flexibility = 7.70 (Judge flexibility was rated by a judge with a trained sensation to assess tissue flexibility on a scale of 0 to about 9.5). For comparison, a typical softness value for a through-dried material having similar strength is 7.15. Example 9 Southern Hardwood Craft Fiber (Coo
sa River-59) was pulped at 10% strength for 15 minutes and dehydrated to 28% strength. Debonder [Berocell (Bellocell 584)] with dry fiber 1
An amount of 10 pounds per ton was added to this pulp. The pulp was then fed to a Maure shaft disintegrator. This disintegrator was operated at 160 ° F with a power input of 2.2 HPD / T.

The resulting crushed hardwood
The fibers were processed into a two layer tissue having a softwood layer and a hardwood layer. Especially, Northern Softwood Craft Fiber (LongLac-1)
9) was pulped at 4% consistency for 60 minutes, while the disintegrated hardwood fiber was pulped at 4% strength for 2 minutes. Each layer was independently formed on a separate forming fabric at a concentration of 0.05%, and the resulting webs were couched together at about 50% per minute at a concentration of about 10% to form a single layer web. Formed. The resulting layered web is conveyed to a papermaking felt and then pressed against the surface of a Yankee dryer where it is dried to 1.
Creeping was performed at a creep ratio of 3. The dryer side of this layered web was composed entirely of softwood fibers and had a basis weight of 7.25 lb / 2880 ft ² (dryer basis weight). The air side of this web was composed of all of the same basis weight of disintegrated hardwood fibers. After creeping, the tissue was wound on bath tissue rolls with minimal pulling force.

The resulting tissue has a tensile force =
689 g / 3 inch width (machine direction) and 466 g / 3 inch width (machine direction), elongation = 32% (machine direction) and 5.6% (machine direction), and flexibility by judges = 7.65. For comparison, a typical softness value for through-dried material having similar strength is 7.30.

Examples 8 and 9 both demonstrate the flexibility advantage of treating virgin hardwood fibers by a disintegrator according to the method of the present invention to make wet-pressed tissues. It should be understood that the above examples given for purposes of illustration should not be construed as limiting the scope of the invention, which is defined by the following claims.

[Brief description of drawings]

FIG. 1 is a schematic flow diagram of an apparatus used to determine a TD index.

2 is an enlarged perspective view of the sample holder of the apparatus of FIG. 1 having a sliding sample tray used to mount the sample holder on the drying apparatus.

FIG. 3 shows a representative plot of pressure drop versus water content that occurs while testing a sample using the apparatus described in FIG. 1 above.

FIG. 4 is a schematic process flow diagram of a method of treating fibers in accordance with the present invention using a shaft disintegrator to treat the fibers.

5 is a cutaway perspective view of the shaft disintegrator of FIG. 4. FIG.

FIG. 6 is another schematic process flow of the method according to the invention using a pair of Bivis machines in series.

[Explanation of symbols]

 1 Compressor 2 Condensed Water Separator 3 Molecular Sieve 4 Compressed Air Dryer 5 Surge Tank 6, 7 Oil Heat Exchanger 8 Humidity Monitor 9 Gate Control Valve 10 Orifice Plate 11 Manometer 12 Sample Housing 13 Sample Tray 14 Aeration Device 16 Differential temperature sensor 17 Differential pressure sensor 18 Humidity monitoring device 19 Data collection system 20 Computer

Front Page Continuation (72) Inventor Robert John McColin United States Wisconsin 54956 Nina Nicolette Boulevard 907 (72) Inventor Christine Anne George United States Wisconsin 54914 Appleton Unit Dee Michael Court 2149 (72) Inventor Hun Yeoh Chen United States Wisconsin 54915 Appleton White Birch Lane 3216

Claims (36)

[Claims] 1. A step of: (a) forming an aqueous suspension composed of papermaking fibers having a concentration of about 20% or higher; (b) drying the aqueous suspension at a temperature of 75 ° F. or higher. Passing about 1 hp-day or more of power per ton of fiber through a shaft disintegrator, wherein the TD index of the fiber is increased by about 25% or more; (c) the fiber Through a tissue making headbox to form a wet web; and (d) drying the web to form a dry tissue. 2. The method of claim 1, wherein the TD index is increased by about 50% or more. 3. The method of claim 1, wherein the TD index is increased by about 75% or more. 4. The method of claim 1, wherein the temperature is about 150 ° F. or higher. 5. The method of claim 1, wherein the temperature is about 210 ° F. or higher. 6. The method of claim 1, wherein the temperature is about 220 ° F. or higher. 7. The method of claim 1, wherein the power input is about 2 hp-day or more per ton of fiber. 8. The method of claim 1, wherein the concentration is about 20-60% by weight. 9. The above concentration is about 30 to about 50% by weight.
The method of claim 1, wherein: 10. The method of claim 1, wherein the papermaking fiber is a secondary fiber. 11. The method of claim 1, wherein the papermaking fibers are virgin hardwood fibers. 12. A softening agent is added to the suspension before the aqueous suspension of papermaking fibers passes through the shaft disintegrator. Method. 13. A method according to claim 1, characterized in that a softening agent is added to said suspension after said aqueous suspension has passed through said shaft disintegrator. 14. The method of claim 1 wherein said wet web is flash dried. 15. A through-dried tissue paper made from a raw material composed of at least about 25% by dry weight of secondary fibers, said raw material having a TD index of about 0.15 or greater. Tissue paper above. 16. The through-dried sheet according to claim 15, wherein the raw material has a TD index of about 0.2 or more. 17. The through-drying paper according to claim 15, wherein the raw material has a TD index of about 0.3 or more. 18. The through-drying paper according to claim 15, wherein the raw material has a TD index of about 0.5 or more. 19. A through-dried paper according to claim 15 made from a raw material having at least about 50 dry weight percent secondary fiber. 20. The through-dried sheet of claim 15 made from a feedstock having at least about 75 dry weight percent secondary fiber. 21. Manufactured from a feedstock having a secondary fiber content of about 100 dry weight percent.
Aerated dry paper according to 5. 22. (a) forming an aqueous suspension composed of secondary fibers having a concentration of about 20% or higher; (b) drying the aqueous suspension at a temperature of 75 ° F or higher. Passing at least about 1 horsepower-day or more of power per ton of fiber through a shaft disintegrator, wherein the TD index of the fiber is increased to about 0.15 or more; (c) Feeding the fibers through a tissue making headbox to form a wet web; and (d) air-drying the web to form an air-dried tissue. A method for producing a through-drying tissue. 23. The method of claim 22, wherein the fiber resulting from step (b) has a TD index greater than or equal to about 0.2. 24. The method of claim 22, wherein the fiber resulting from step (b) has a TD index greater than or equal to about 0.3. 25. The method of claim 22, wherein the fiber resulting from step (b) has a TD index greater than or equal to about 0.5. 26. The method of claim 22, wherein the temperature is about 150 ° F. or higher. 27. The method of claim 22, wherein the temperature is about 210 ° F. or higher. 28. The method of claim 22, wherein the temperature is about 220 ° F. or higher. 29. The method of claim 22, wherein the power input is about 2 hp-day or more per ton of fiber. 30. The method of claim 22, wherein the concentration is about 20-60%. 31. The method of claim 22, wherein the concentration is about 30% to about 50%. 32. A tissue produced by the method according to claim 1 or 22. 33. A tissue comprising crushed virgin hardwood fibers. 34. The tissue of claim 33 which is comprised of blended softwood fibers and disintegrated virgin hardwood fibers. 35. Inner layer of softwood fiber and outer 2 of disintegrated virgin hardwood fiber.
34. Tissue according to claim 33, characterized in that it is constituted by layers. 36. The ratio of the softwood fibers to the hardwood fibers is about 1:
36. The tissue according to claim 35, wherein the tissue is 1.