CA1091073A - Paper composition - Google Patents
Paper compositionInfo
- Publication number
- CA1091073A CA1091073A CA309,601A CA309601A CA1091073A CA 1091073 A CA1091073 A CA 1091073A CA 309601 A CA309601 A CA 309601A CA 1091073 A CA1091073 A CA 1091073A
- Authority
- CA
- Canada
- Prior art keywords
- fibers
- tear
- acrylic
- paper sheet
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- 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
- D21H5/00—Special paper or cardboard not otherwise provided for
- D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
- D21H5/20—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres
Landscapes
- Paper (AREA)
- Nonwoven Fabrics (AREA)
Abstract
PAPER COMPOSITION
ABSTRACT OF THE DISCLOSURE
A nonwoven paper sheet comprising cellulosic fibers and hydrophilic fibers, such as acrylic, polyester or aramid fibers. Acrylic fibers are added in a weight amount of from 0.2% to 40% based upon the total weight of the paper sheet. The preferred addition of acrylic fibers is in a weight amount of from 0.2% to 10% based upon the total weight of the paper sheet.
Polyester fibers are added in a weight amount of from 0.5% to 40% based upon the total weight of the paper sheet. The pre-ferred addition of polyester fibers is in a weight amount of from 0.5% to 10% based upon the total weight of the paper sheet.
Aramid fibers are added in a weight amount of from 0.2% to 20%
based upon the total weight of the paper sheet. The preferred addition of aramid fibers is in a weight amount of from 0.2% to 5% based upon the total weight of the paper sheet.
ABSTRACT OF THE DISCLOSURE
A nonwoven paper sheet comprising cellulosic fibers and hydrophilic fibers, such as acrylic, polyester or aramid fibers. Acrylic fibers are added in a weight amount of from 0.2% to 40% based upon the total weight of the paper sheet. The preferred addition of acrylic fibers is in a weight amount of from 0.2% to 10% based upon the total weight of the paper sheet.
Polyester fibers are added in a weight amount of from 0.5% to 40% based upon the total weight of the paper sheet. The pre-ferred addition of polyester fibers is in a weight amount of from 0.5% to 10% based upon the total weight of the paper sheet.
Aramid fibers are added in a weight amount of from 0.2% to 20%
based upon the total weight of the paper sheet. The preferred addition of aramid fibers is in a weight amount of from 0.2% to 5% based upon the total weight of the paper sheet.
Description
lO~l(r~;~
1 The present disclosure relates to a new a~ novel paper construction which substantially increases the tear strength of the sheet while maintaining the tensile strength of the sheet within acceptable limits.
The desire for a paper construction having an increased tear strength has arisen because of the desirability of produc-ing a lighter sheet, that is, less weight per unit area, or a stronger sheetof the same weight per unit area. The advantages of a lighter sheet include but are not limited to lower shipping costs, lower postal rates, lower raw material costs and the in-herent weight requirement in the finished product, as well as stronger packaging papers.
It is known in the prior art that tear and tensile strength are related and typically as tensile strength increases tear strength decreases. A problem inherent in some of the prior 1 art in reducing the paper weight was that if the weight was re-jl duced the tear strength dropped to an unacceptable level. As refining of the fibers increases tensile strength increases and inversely, as refining energy is decreased tear strength in-creases. Chemicals can be added to paper furnishes to increase tensile strength; however, normally tear strength cannot be im-proved with chemical additions. Longer fibérs normally provide a higher tear strength than shorter fibers.
Problems that arise with an unacceptable tear strength include tears in the wet web of a paper-making machine resulting in machine down time and workman expense as well as exposing workmen to hazards in rethreading the broken web. The same prob-lems carry over to use of the finished paper sheet in a printing press when this is the end use of the sheet.
, . . .
l(lg~073 1 A typical known grade of paper used for printing con-sists of 50~ bleached kraft pulp and 50% groundwood pulp which can be utilized to produce a 35 pound paper. This designation describes the weight per 3300 square feet of the paper produced which is approximately 52 grams per square meter. The kraft fi-bers may be on the order of usually 2 or 3 millimeters in length, may be 2 to S millimeters and they primarily contribute to the tear and tensile strength of the sheet and to machine runability.
The groundwood tends to fill in voids in the sheet and contributes to the sheet's smoothness,opacity and denseness.
In this type of construction prior art practice would increase the tear strength by raising the percentage of kraft and lowering the percentage of groundwood. From a practical standpoint the kraft percentage can only be increased to a certain point because it is more expensive and there is only so much available. Most bleached kraft pulps have fibers with a length of up to 2 or 3 millimeters although some fibers may be from 2 to S millimeters in length and it is difficult to obtain such fi-bers with any greater length.
The present invention concerns itself with the finding that the addition of certain amounts of a hydrophilic fiber to natural cellulosic fibers in a nonwoven paper sheet construction produces an unusual and unexpected increase in the tear strength of the paper sheet. Nonwoven means there is no weaving of fibers or twisting of fibers into threads. As a matter of example the use of the present invention enables the manufacture of a 20 pound (approximately 30 grams per square meter) paper which has a tear strength of a prior art paper of about 35 pounds (approxi-mately 52 grams per ~uare meter).
109iO73 1 The hydrophilic fibers of the present invention are acrylic, polyester and aramid fibers. The hydrophilic fibers usable in the present invention are preferably of a 1.5 to 6.0 denier, non-crimped and should preferably be long, for example on the order of from 1/8" to 1/2" (approximately 3.2 millimeters to 12.7 millimeters) in length. It is recognized that fibers of -a denier less than 1.5 may be used.
The present disclosure reveals that additions of acry-lic and polyester fibers in an amount of from a small but effec-tive amount up to 40% of the total sheet weight produce an in-crease in the tear strength of non-woven paper sheet. In the case of aramid fibers the present disclosure indicates that they should be added in an amount of from a small but effective amount up to 20% to produce an increase in the tear strength. In the case of additions of acrylic and polyester fibers the tear strength increases substantially linearly up to additions of 25 ¦ and at this point show a lower increase up to about a 40% addi-I tion. In the case of the addition of aramid fibers the tear I strength increases substantially linearly up to an aramid addi-~l 20 tion of 20% at which point the tear strength decreases with fur-ther additions of the aramid fibers. In the case of tensile strength it does decrease as tear increases when any of the three disclosed fibers are added. Test results indicate that the small but effective amount in the case of acrylic and aramid fibers is on the order of 0.2~ and in the case of polyester fibers is on the order of 0.5% which amounts give a measurable increase in the tear strength.
In comparing tear strength improvements at constant tensile (efficiency) it has been found as a general proposition that as the amount of hydrophilic fibers increases, a lower effi-lU~31(~73 1 ciency in tear improvement at constant tensile values results.
It appears that a nearly linear change in tear at constant ten-sile is obtained in the case of additions to acrylic and poly-ester fibers when added in from a small but effective amount up to about 10% and then a decreased change in tear at constant tensile results in additions above 10%. The same is true in the case of additions of aramid fibers but only up to about a 5%
addition after which a decreased rate of change in tear at con-stant tensile results.
The definition of acrylic fibers applicable to the pre-sent invention are those manufactured fibers in which the fiber-forming substance is any long chain synthetic polymer composed of about at least 85% by ~eight of acrylonitrile units. These acrylonitrile units are usually copolymerized with materials such as methcrylic acid and acrylic acid. Such fibers are sold, for example, under the trademarks ACRILAN, CRESLAN, ORLON and ZEFRAN.
The definition of polyester fibers applicable to the present invention are those manufactured fibers in which the fiber-forming substance is any long chain synthetic polymer com-posed of at least 85% by weight of an ester of a substituted aro-matic carboxylic acid, including but not restricted to substituted terephthalate units. Typical raw materials used in the manufac-ture of these fibers are dimethyl terephthalate, terephthalic acid,and ethylene glycol. Such fibers are sold for example under the trademarks DACRON, FORTREL, KODEL and TREVIRA.
The definition of aramid fibers applicable to the pre-sent invention are those manufactured fibers in which the fiber-forming substance is a long-chain synthetic polyamide in which at `` B ~4~
.. . .
109~073 1 least 85~ of the amide linkages are attached directly to the two aromatic rings. Typical raw materials used in the production of such fibers are meta and para-phenylene diamine and iso- and terephthaloyl chloride. These fibers are sold for example under the trademarks of KEVLAR and NOMEX.
~ ydrophilic fibers usable under this invention are de-fined as ones having a substantial degree of ionic character, and thus high water dispersability. Examples of hydrophilic groups on fiber surfaces would be the acrylic acid groups on the acrylic fibers, or the carboxylic groups on the polyester fibers, or the amide groups on the aramid fibers. Conversely, polyethy-lene or polypropylene fibers have a more hydrophobic and less a hydrophilic nature.
Other objects and a fuller understanding of this inven-tion may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:
Figure 1 is a graph illustrating the relationship of tear vs. beating time for three paper compositions, namely a control to which no acrylic fiber has been added; a kraft pulp to which has been added 5 percent of a 3/8" ~9.6 millimeters) x 3.0 denier acrylic fiber; and a kraft pulp to which has been added 5 percent of a 1/4" (6.35 millimeters) x 3.0 denier acrylic fiber;
Figure 2 is a graph illustrating the relationship of tensile strength vs. beating time for the same paper compositions shown in Figure l;
Figure 3 is a graph illustrating the relationship of tear vs. percent acrylic fibers added to kraft pulp;
Figure 4 is a graph illustrating the relationship of tensile strength vs. percent acrylic fibers added as in Figure 3.
'' ~
1(~'31073 1 Figure 5 is a graph illustrating the relationship of tear vs. tensile strength of the compositions illustrated in Figures 3 and 4;
Figure 6 is a graph illustrating the relationship of the efficiency of the acrylic fibers vs. percent acrylic fibers added to the paper composition;
Figures 7-12 are photo micrographs taken at about 100 times magnification and illustrating various compositions that are found in Figure 3, namely 100~ kraft; 10~ acrylic addition;
20~ acrylic addition; 30% acrylic addition; 40% acrylic addition;
and 50% acrylic addition;
Figure 13 is a graph illustrating the relationship of varying percentages of kraft and groundwood in a paper sheet vs.
the wet web strength for a kraft-groundwood sheet and a kraft-groundwood sheet where 5 percent of the kraft has been replaced with acrylic fibers;
Figure 14 is a graph illustrating the relationship of tear vs. percent polyester and aramid fibers added to a kraft pulp;
Figure 15 is a graph illustrating the relationship of tensile strength vs. percent polyester and aramid fibers added to a kraft pulp as in Figure 14;
Figure 16 is a graph illustrating the relationship of tear vs. tensile strength of the compositions given in Table XI;
Figure -17 is a graph illustrating the relationship of tear vs. tensile strength of the compositions given in Table XII;
Figure 1~ is a graph illustrating the relationship of the percent change in tear of the polyester and aramid fibers vs.
percent fiber added to the paper composition;
I
109~073 1 Figure 19 is a graph illustrating the relationship of the increase in tear (percent) vs. fiber cost per ton for acry-lic,polyester and aramid fibers;
Figure 20 is a photo micrograph taken at about 120 times magnification and illustrating a 10% polyester-90% kraft fiber composition; and Figure 21 is a photo micrograph taken at about 120 times magnification and illustrating a 10~ aramid-90% kraft fi-ber composition.
The teachings of the present invention are revealed in the following test results which illustate the addition of acry-lic, polyester and aramid fibers to cellulose fibers.
The first tests comprise the addition of two sizes of uncrimped acrylic fibers 3/8" (9.6 millimeters) x 3.0 denier and 1/4" (6.35 millimeters) x 3.0 denier in varying percentages to a medium yield unbleached kraft pulp produced at the St. Regis Paper Company plant at Jacksonville, Florida, U.S.A.
In each of the test samples were ta~en from each beater run at 5, 10, 15, 30 and 45 minute intervals. Five sets of hand-2g sheets (60 grams/meter2) were made from each beater run and thedata appearing in the following Tables I-V were obtained from tests conducted on these handsheets.
3~ .
1091lr73 1 Table I
CONTROL (No Acrylic Fiber Added) Beating Time, Minutes _ _ _ . _ Canadian Standard Freeness Test (CSF), mls. 2 756 747 705 580 405 Basis weight, g/m 60.1 59.9 60.0 59.3 59.9 Burst factor 35.9 45.7 54.5 63.8 69.0 Tensile (Breaking Length in Km) 5.98 7.13 8.20 9.09 9.61 Tear Factor 229 199 171 156 137 Table II
1 The present disclosure relates to a new a~ novel paper construction which substantially increases the tear strength of the sheet while maintaining the tensile strength of the sheet within acceptable limits.
The desire for a paper construction having an increased tear strength has arisen because of the desirability of produc-ing a lighter sheet, that is, less weight per unit area, or a stronger sheetof the same weight per unit area. The advantages of a lighter sheet include but are not limited to lower shipping costs, lower postal rates, lower raw material costs and the in-herent weight requirement in the finished product, as well as stronger packaging papers.
It is known in the prior art that tear and tensile strength are related and typically as tensile strength increases tear strength decreases. A problem inherent in some of the prior 1 art in reducing the paper weight was that if the weight was re-jl duced the tear strength dropped to an unacceptable level. As refining of the fibers increases tensile strength increases and inversely, as refining energy is decreased tear strength in-creases. Chemicals can be added to paper furnishes to increase tensile strength; however, normally tear strength cannot be im-proved with chemical additions. Longer fibérs normally provide a higher tear strength than shorter fibers.
Problems that arise with an unacceptable tear strength include tears in the wet web of a paper-making machine resulting in machine down time and workman expense as well as exposing workmen to hazards in rethreading the broken web. The same prob-lems carry over to use of the finished paper sheet in a printing press when this is the end use of the sheet.
, . . .
l(lg~073 1 A typical known grade of paper used for printing con-sists of 50~ bleached kraft pulp and 50% groundwood pulp which can be utilized to produce a 35 pound paper. This designation describes the weight per 3300 square feet of the paper produced which is approximately 52 grams per square meter. The kraft fi-bers may be on the order of usually 2 or 3 millimeters in length, may be 2 to S millimeters and they primarily contribute to the tear and tensile strength of the sheet and to machine runability.
The groundwood tends to fill in voids in the sheet and contributes to the sheet's smoothness,opacity and denseness.
In this type of construction prior art practice would increase the tear strength by raising the percentage of kraft and lowering the percentage of groundwood. From a practical standpoint the kraft percentage can only be increased to a certain point because it is more expensive and there is only so much available. Most bleached kraft pulps have fibers with a length of up to 2 or 3 millimeters although some fibers may be from 2 to S millimeters in length and it is difficult to obtain such fi-bers with any greater length.
The present invention concerns itself with the finding that the addition of certain amounts of a hydrophilic fiber to natural cellulosic fibers in a nonwoven paper sheet construction produces an unusual and unexpected increase in the tear strength of the paper sheet. Nonwoven means there is no weaving of fibers or twisting of fibers into threads. As a matter of example the use of the present invention enables the manufacture of a 20 pound (approximately 30 grams per square meter) paper which has a tear strength of a prior art paper of about 35 pounds (approxi-mately 52 grams per ~uare meter).
109iO73 1 The hydrophilic fibers of the present invention are acrylic, polyester and aramid fibers. The hydrophilic fibers usable in the present invention are preferably of a 1.5 to 6.0 denier, non-crimped and should preferably be long, for example on the order of from 1/8" to 1/2" (approximately 3.2 millimeters to 12.7 millimeters) in length. It is recognized that fibers of -a denier less than 1.5 may be used.
The present disclosure reveals that additions of acry-lic and polyester fibers in an amount of from a small but effec-tive amount up to 40% of the total sheet weight produce an in-crease in the tear strength of non-woven paper sheet. In the case of aramid fibers the present disclosure indicates that they should be added in an amount of from a small but effective amount up to 20% to produce an increase in the tear strength. In the case of additions of acrylic and polyester fibers the tear strength increases substantially linearly up to additions of 25 ¦ and at this point show a lower increase up to about a 40% addi-I tion. In the case of the addition of aramid fibers the tear I strength increases substantially linearly up to an aramid addi-~l 20 tion of 20% at which point the tear strength decreases with fur-ther additions of the aramid fibers. In the case of tensile strength it does decrease as tear increases when any of the three disclosed fibers are added. Test results indicate that the small but effective amount in the case of acrylic and aramid fibers is on the order of 0.2~ and in the case of polyester fibers is on the order of 0.5% which amounts give a measurable increase in the tear strength.
In comparing tear strength improvements at constant tensile (efficiency) it has been found as a general proposition that as the amount of hydrophilic fibers increases, a lower effi-lU~31(~73 1 ciency in tear improvement at constant tensile values results.
It appears that a nearly linear change in tear at constant ten-sile is obtained in the case of additions to acrylic and poly-ester fibers when added in from a small but effective amount up to about 10% and then a decreased change in tear at constant tensile results in additions above 10%. The same is true in the case of additions of aramid fibers but only up to about a 5%
addition after which a decreased rate of change in tear at con-stant tensile results.
The definition of acrylic fibers applicable to the pre-sent invention are those manufactured fibers in which the fiber-forming substance is any long chain synthetic polymer composed of about at least 85% by ~eight of acrylonitrile units. These acrylonitrile units are usually copolymerized with materials such as methcrylic acid and acrylic acid. Such fibers are sold, for example, under the trademarks ACRILAN, CRESLAN, ORLON and ZEFRAN.
The definition of polyester fibers applicable to the present invention are those manufactured fibers in which the fiber-forming substance is any long chain synthetic polymer com-posed of at least 85% by weight of an ester of a substituted aro-matic carboxylic acid, including but not restricted to substituted terephthalate units. Typical raw materials used in the manufac-ture of these fibers are dimethyl terephthalate, terephthalic acid,and ethylene glycol. Such fibers are sold for example under the trademarks DACRON, FORTREL, KODEL and TREVIRA.
The definition of aramid fibers applicable to the pre-sent invention are those manufactured fibers in which the fiber-forming substance is a long-chain synthetic polyamide in which at `` B ~4~
.. . .
109~073 1 least 85~ of the amide linkages are attached directly to the two aromatic rings. Typical raw materials used in the production of such fibers are meta and para-phenylene diamine and iso- and terephthaloyl chloride. These fibers are sold for example under the trademarks of KEVLAR and NOMEX.
~ ydrophilic fibers usable under this invention are de-fined as ones having a substantial degree of ionic character, and thus high water dispersability. Examples of hydrophilic groups on fiber surfaces would be the acrylic acid groups on the acrylic fibers, or the carboxylic groups on the polyester fibers, or the amide groups on the aramid fibers. Conversely, polyethy-lene or polypropylene fibers have a more hydrophobic and less a hydrophilic nature.
Other objects and a fuller understanding of this inven-tion may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:
Figure 1 is a graph illustrating the relationship of tear vs. beating time for three paper compositions, namely a control to which no acrylic fiber has been added; a kraft pulp to which has been added 5 percent of a 3/8" ~9.6 millimeters) x 3.0 denier acrylic fiber; and a kraft pulp to which has been added 5 percent of a 1/4" (6.35 millimeters) x 3.0 denier acrylic fiber;
Figure 2 is a graph illustrating the relationship of tensile strength vs. beating time for the same paper compositions shown in Figure l;
Figure 3 is a graph illustrating the relationship of tear vs. percent acrylic fibers added to kraft pulp;
Figure 4 is a graph illustrating the relationship of tensile strength vs. percent acrylic fibers added as in Figure 3.
'' ~
1(~'31073 1 Figure 5 is a graph illustrating the relationship of tear vs. tensile strength of the compositions illustrated in Figures 3 and 4;
Figure 6 is a graph illustrating the relationship of the efficiency of the acrylic fibers vs. percent acrylic fibers added to the paper composition;
Figures 7-12 are photo micrographs taken at about 100 times magnification and illustrating various compositions that are found in Figure 3, namely 100~ kraft; 10~ acrylic addition;
20~ acrylic addition; 30% acrylic addition; 40% acrylic addition;
and 50% acrylic addition;
Figure 13 is a graph illustrating the relationship of varying percentages of kraft and groundwood in a paper sheet vs.
the wet web strength for a kraft-groundwood sheet and a kraft-groundwood sheet where 5 percent of the kraft has been replaced with acrylic fibers;
Figure 14 is a graph illustrating the relationship of tear vs. percent polyester and aramid fibers added to a kraft pulp;
Figure 15 is a graph illustrating the relationship of tensile strength vs. percent polyester and aramid fibers added to a kraft pulp as in Figure 14;
Figure 16 is a graph illustrating the relationship of tear vs. tensile strength of the compositions given in Table XI;
Figure -17 is a graph illustrating the relationship of tear vs. tensile strength of the compositions given in Table XII;
Figure 1~ is a graph illustrating the relationship of the percent change in tear of the polyester and aramid fibers vs.
percent fiber added to the paper composition;
I
109~073 1 Figure 19 is a graph illustrating the relationship of the increase in tear (percent) vs. fiber cost per ton for acry-lic,polyester and aramid fibers;
Figure 20 is a photo micrograph taken at about 120 times magnification and illustrating a 10% polyester-90% kraft fiber composition; and Figure 21 is a photo micrograph taken at about 120 times magnification and illustrating a 10~ aramid-90% kraft fi-ber composition.
The teachings of the present invention are revealed in the following test results which illustate the addition of acry-lic, polyester and aramid fibers to cellulose fibers.
The first tests comprise the addition of two sizes of uncrimped acrylic fibers 3/8" (9.6 millimeters) x 3.0 denier and 1/4" (6.35 millimeters) x 3.0 denier in varying percentages to a medium yield unbleached kraft pulp produced at the St. Regis Paper Company plant at Jacksonville, Florida, U.S.A.
In each of the test samples were ta~en from each beater run at 5, 10, 15, 30 and 45 minute intervals. Five sets of hand-2g sheets (60 grams/meter2) were made from each beater run and thedata appearing in the following Tables I-V were obtained from tests conducted on these handsheets.
3~ .
1091lr73 1 Table I
CONTROL (No Acrylic Fiber Added) Beating Time, Minutes _ _ _ . _ Canadian Standard Freeness Test (CSF), mls. 2 756 747 705 580 405 Basis weight, g/m 60.1 59.9 60.0 59.3 59.9 Burst factor 35.9 45.7 54.5 63.8 69.0 Tensile (Breaking Length in Km) 5.98 7.13 8.20 9.09 9.61 Tear Factor 229 199 171 156 137 Table II
2-1/2~ of 3/8" (9.6 millimeters) x 3.0 DENIER ACRYLIC FIBER
(Added after Beating) Beati'ng Time',' Minutes -C S F, mls. 2 752 724 691 596 430 Basis weight, g/m 61.7 59.9 65.3 60.8 62.0 Burst factor 33.4 40.5 52.2 62.6 67.7 Tensile, Km 5.81 6.69 7.92 8.72 9.38 Tear factor 255 235 215 178 163 Table III
5~ of 3/8" (9.6 millimeters) x 3.0 DENIER ACRYLIC FIBER
(Added after Bea-ting) Beating Time, Minutes C S F, mls. 2 734 740 715 610 465 Basis weight, g/m 57.0 61.9 62.4 60.6 61.6 Burst factor 31.4 39.5 47.8 55.2 63.7 Tensile, Km 5.48 6.15 7.22 7.97 8.86 Tear factor 262 257 230 203 194 ~ 1 Table IV
: 2-1/2~ of 1/4" (6.35 millimeters) x 3.0 DENIER ACRYLIC FIBER
, (Added after Beating) i Beating Time, Minutes C S F, mls. 2 756 743 705 596 423 Basis weight, g/m 59.2 61.7 54.9 59.4 63.9 Burst 33.3 41.2 51.0 57.8 67.3 Tensile, Km 5.86 6.54 7.70 8.67 9.58 Tear 250 218 186 178 175 Table V
5% of 1/4" (6.35 millimeters) x 3.0 DENIER ACRYLIC FIBER
(Added after Beating) ;
Beating Time, Minutes C S F, mls. 2 762 733 715 616 454 Basis weight, g/m 56.g 60.4 62.0 60.7 62.5 Burst 29.9 38.9 49.0 59.3 63.1 Tensile, Km 5.08 6.31 7.26 8.44 8.23 Tear 267 228 217 192 183 Table VI shows test results where a 5~ addition of a 1/4" (6.35 millimeters) x 3.0 denier acrylic fiber was made to the pulp prior to the beater run.
Table VI
BEATER RUN CONTAINING 5% of 1/4" (6.35 millimeters x 3.0 DENIER ACRYLIC FIBER
Beating Time _ inutes _ 15 30 45 Basis weight, g/m 62.5 61.3 64.5 61.8 59.7 Burst 33.3 43.4 54.1 58.8 64.1 Tensile 5.63 7.06 8.01 8.87 8.11 - Tear 266 214 175 169 133 ~091073 1 In the test results indicated herein the Canadian Standard Freeness (CSF) is a measure of the rate at which a di-lute suspension of pulp may be dewatered. The units of this test are expressed in milliliters.
The burst streng~ as expressed in the tablets is ex-pressed as a dimensionless number. This test is a measure of the hydrostatic pressure required to produce rupture of the material when pressure is applied by means of a liquid at a controlled, increasing rate to a circular area of the material under test.
The test material is initially flat and held rigidly at the cir-cumference. During the test the sample must be free to bulge un-der the increasing pressure. The tests herein for burst strength were conducted under Tappi Test No. T-403 os-76 ~1976). Equiva-lent tests are CPPA (Canadian) Test No. D.8 (January 1964); ASTM
Test No. ~ 774-67 (1971); and ISO (International Organization for Standards) Test No. 2758-1974 (E~.
The tear resistanoe as expressed in the tables is ex-pressed as a dimensionless number. Tear is the average force normally in grams, to tear a single sheet of paper after the tear has been started. The test consists of measuring the work done when a sample of the paper is tor~ through a specified distance.
The work is ~ne partly in rupturi~g the paper along the line of tear and partly in bending the paper as it is being torn. The tests herein for tear strength were conducted under Tappi Test No. T-414 ts-65 (1965). E~uivalent tests are CPPA Test No. D.9 (September 1965); ASTM Test No. D 689-62 (1944); SCAN (Scandanav-ian) Test No. P 11:73; and ISO Test No. 1974-1974 (E).
The tensile strength as expressed in.the tables is ex-pressed as kilometers. The tensile strength is the maximum tensile ~(J91073 force per unit width that a piece of paper or board will stand before breaking. This test is in effect the length of a paper sample necessary to cause breaking of the sample as the sample is held at one end. The tests herein for tensile strength were con-ducted under Tappi Test No. T-494 os-70 (1970). Ec~uivalent tests are CPPA Test No. D.6 (September 1961); ASTM Test No. D 828-60 (1971); SCA~ Test No. P 16:76; and ISO Test No. 1924-1976 (E).
Figure 1 is a graph constructed from the data obtained above (Tables III and V) and illustrates that a significantly 10 higher tear strength is obtained with the addition of 5% acrylic fibers as compared to the control which contained no acrylic fi-ber addition. Figure 1 also affirms the general proposition that as beating time increases, tear strength decreases.
Figure 2 is a graph similar to Figure 1 but showing tensile strength as a function of beating time and compares 5% -1/4" (6.35 millimeters) x 3.0 denier acrylic addition and 5% -
(Added after Beating) Beati'ng Time',' Minutes -C S F, mls. 2 752 724 691 596 430 Basis weight, g/m 61.7 59.9 65.3 60.8 62.0 Burst factor 33.4 40.5 52.2 62.6 67.7 Tensile, Km 5.81 6.69 7.92 8.72 9.38 Tear factor 255 235 215 178 163 Table III
5~ of 3/8" (9.6 millimeters) x 3.0 DENIER ACRYLIC FIBER
(Added after Bea-ting) Beating Time, Minutes C S F, mls. 2 734 740 715 610 465 Basis weight, g/m 57.0 61.9 62.4 60.6 61.6 Burst factor 31.4 39.5 47.8 55.2 63.7 Tensile, Km 5.48 6.15 7.22 7.97 8.86 Tear factor 262 257 230 203 194 ~ 1 Table IV
: 2-1/2~ of 1/4" (6.35 millimeters) x 3.0 DENIER ACRYLIC FIBER
, (Added after Beating) i Beating Time, Minutes C S F, mls. 2 756 743 705 596 423 Basis weight, g/m 59.2 61.7 54.9 59.4 63.9 Burst 33.3 41.2 51.0 57.8 67.3 Tensile, Km 5.86 6.54 7.70 8.67 9.58 Tear 250 218 186 178 175 Table V
5% of 1/4" (6.35 millimeters) x 3.0 DENIER ACRYLIC FIBER
(Added after Beating) ;
Beating Time, Minutes C S F, mls. 2 762 733 715 616 454 Basis weight, g/m 56.g 60.4 62.0 60.7 62.5 Burst 29.9 38.9 49.0 59.3 63.1 Tensile, Km 5.08 6.31 7.26 8.44 8.23 Tear 267 228 217 192 183 Table VI shows test results where a 5~ addition of a 1/4" (6.35 millimeters) x 3.0 denier acrylic fiber was made to the pulp prior to the beater run.
Table VI
BEATER RUN CONTAINING 5% of 1/4" (6.35 millimeters x 3.0 DENIER ACRYLIC FIBER
Beating Time _ inutes _ 15 30 45 Basis weight, g/m 62.5 61.3 64.5 61.8 59.7 Burst 33.3 43.4 54.1 58.8 64.1 Tensile 5.63 7.06 8.01 8.87 8.11 - Tear 266 214 175 169 133 ~091073 1 In the test results indicated herein the Canadian Standard Freeness (CSF) is a measure of the rate at which a di-lute suspension of pulp may be dewatered. The units of this test are expressed in milliliters.
The burst streng~ as expressed in the tablets is ex-pressed as a dimensionless number. This test is a measure of the hydrostatic pressure required to produce rupture of the material when pressure is applied by means of a liquid at a controlled, increasing rate to a circular area of the material under test.
The test material is initially flat and held rigidly at the cir-cumference. During the test the sample must be free to bulge un-der the increasing pressure. The tests herein for burst strength were conducted under Tappi Test No. T-403 os-76 ~1976). Equiva-lent tests are CPPA (Canadian) Test No. D.8 (January 1964); ASTM
Test No. ~ 774-67 (1971); and ISO (International Organization for Standards) Test No. 2758-1974 (E~.
The tear resistanoe as expressed in the tables is ex-pressed as a dimensionless number. Tear is the average force normally in grams, to tear a single sheet of paper after the tear has been started. The test consists of measuring the work done when a sample of the paper is tor~ through a specified distance.
The work is ~ne partly in rupturi~g the paper along the line of tear and partly in bending the paper as it is being torn. The tests herein for tear strength were conducted under Tappi Test No. T-414 ts-65 (1965). E~uivalent tests are CPPA Test No. D.9 (September 1965); ASTM Test No. D 689-62 (1944); SCAN (Scandanav-ian) Test No. P 11:73; and ISO Test No. 1974-1974 (E).
The tensile strength as expressed in.the tables is ex-pressed as kilometers. The tensile strength is the maximum tensile ~(J91073 force per unit width that a piece of paper or board will stand before breaking. This test is in effect the length of a paper sample necessary to cause breaking of the sample as the sample is held at one end. The tests herein for tensile strength were con-ducted under Tappi Test No. T-494 os-70 (1970). Ec~uivalent tests are CPPA Test No. D.6 (September 1961); ASTM Test No. D 828-60 (1971); SCA~ Test No. P 16:76; and ISO Test No. 1924-1976 (E).
Figure 1 is a graph constructed from the data obtained above (Tables III and V) and illustrates that a significantly 10 higher tear strength is obtained with the addition of 5% acrylic fibers as compared to the control which contained no acrylic fi-ber addition. Figure 1 also affirms the general proposition that as beating time increases, tear strength decreases.
Figure 2 is a graph similar to Figure 1 but showing tensile strength as a function of beating time and compares 5% -1/4" (6.35 millimeters) x 3.0 denier acrylic addition and 5% -
3/8" (9.6 millimeters) x 3.0 denier acrylic addition to a control which contained no addition. It shows that the tensile strength is slightly lower with the acrylic additions; however, they are 20 well within acceptable limits for the purposes of the product of -- the present invention. Figure 2 also illustrates an increase in tensile strength as beating time increases.
In order to determine the optimum amount of acrylic fiber to be added to cellulosic fiber within the teachings of the present invention a series of test handsheets were made by the same procedure outline above with progressively larger amounts of acrylic fiber. The uncrimped acrylic fiber used was 1/4" (6.35 millimeters) x 3.0 denier and was added to a 570 CSF (Canadian Standard Freeness)~ bleached softwove kraft pulp, sold under the ; 1091~73 .
1 trade name of Hibrite pulp. The results of the test are indicated below in Table VII.
Table VII
STRENGTH PROPERTIES OF ACRYLIC FILLED HANDSHEETS
3.0 Denier x 1/4" (6.35 millimeters) Uncrimped Acrylic Fi~er Kraft Acrylic, Tensile, Tear % ~ Km Factor 100 0 10.9 107 10 95 5 9.5 135 8.4 181 7.6 216 6.6 244 5.9 281 5.0 290 3.4 301 2.5 241 The tear and tensile results from Table VII above have been shown in the graphs of Figures 3 and 4 and it will be noted that tear increases and tensile decreases linearly up to a 25%
acrylic addition. Tear increases at a lower rate from 25% up to 40% acrylic addition and then shows a sharp decrease. Tear in-creases over a control (no acrylic addition) at a rate of about 7.3~ for each 1% acrylic added up to a 25% acrylic addition.
Figure 5 is a graph constructed from the date of Table VII showing the tear vs. tensile relationship for the acrylic fi-ber filled sheets and for a control sheet containing no acrylic fiber.
Table VIII has been constructed from data included in Table VII and illustates tear improvements in acrylic filled paper 109~73 .
1 sheets at constant tensile strength. The percent change in tear is calculated by taking the difference between the tear of a con-trol sheet and the tear of an acrylic filled sheet and dividing the difference by the tear of the control sheet. The efficiency is then calculated by dividing the percent change by the percent of acrylic fibers added to the paper sheet.
Table VIII
EFFICIENCY OF ACRYLIC FIBER
Tear of Ten- Control sile Sheet (No Tear of Acrylic Add- of Effici-Acry- ed) at Ten- Acry- % ency, Acry- lic sile of Acry- lic Change ~ Change Kraft, lic Filled lic Filled Filled in %Acrylic % % Sheet Sheet Sheet Tear Added _ 9.~ 110 135 22.7 4.5 ~.4 125 181 44.8 4.5 7.6 135 216 60.0 4.0 6.6 155 244 57.4 2.9 5.9 175 281 60.6 2.4 5.0 195 290 48.7 1.6 3.4 240 301 25.4 0.6 2.5 270 241 -10.7 -0.2 % tear improvement per 1% acrylic fiber added Figure 6 is a graph illustrating these relationships and it will be seen that a constant efficiency is obtained up to about 10% acrylic addition and then a decreased efficiency results as the acrylic fiber in the sheet is increased.
Figures 7-12 are photo micrographs at about 100 magni-fication showing the handsheets from the above tests (Table VII -Figure 3) with varying amounts of acrylic fibers added to the bleached kraft fibers. Figures 7-12 illustrate in visual form the interrelationship between the cellulosic fibers and the acry-lic fibers in their matted nonwov~n condition. ~he Figures 7-12 ~' 1 show respectively 0, 10, 2Q, 30, 40 and 50 percent acrylic con-ditions. The uncrimped nature of the acrylic fibers can also be clearly seen from these figures.
A further series of tests were conducted in a manner similar to those tests discussed above to illustrate the effect in what has been referred to as wet web strength with the re-placement of 5% of the kraft portion of various kraft-groundwood furnishes. The results of these tests are shown in the graph of Figure 13. The groundwood portion of the furnish may be between 20 to 80~ of the total furnish. The wet web strength is common-ly referred to by those skilled in the art and is related to paper making machine runability. It is the work or tensile en-ergy which the wet sheet will absorb at a given stretch, equal to the draw (the speed differential between the wire and the couch~ The wet web strength is attained by integrating the ; stress-strain curve up to a stretch, usually about 3 1/2%, equiv-alent to the draw. The wet web strength values in Figure 13 were obtained at 3'% strain. Figure 13 illustrates clearly the increase in wet web strength for various kraft-groundwood fur-nishes when 5% of the kraft portion of the furnish was replaced with 3/8" (9.6 millimeters)- 3.0 denier uncrimped acrylic fibers.
A test run was made at St. Regis production facilities in Bucksport, Maine. In this run approximateIy 60 english tons of 34 pound letterpress paper containing acrylic and a compar-able amount of control paper from the same pulp, except, without acrylic were made. Comparison tests indicated results similar, or substantially the same as theaforementioned test results set forth herein. In addition the paper was tested in a printing operation on production printing equipment. We found the paper containing acryiic to perform in the printing operation in a man-_ 14 -. i . ~ .
!
1 ner and with results comparable to and the same as the control paper which did not contain acrylic fiber.
In order to determine the optimum amount of polyester fiber to be added to cellulosic fiber a series of test hand sheets were made. The polyester fiber utilized was manufactured by DuPont and was 3/8" (9.6 millimeters) x 3.0 denier and was ' added to a 570 CSF bleached ~raft soft wood pulp. The results of the test are indicated in Table IX.
Table IX
STRENGTH PR~PERTIES OF POLYESTER FILLED HANDSHEETS
3.0 Denier x 3/8" (9.6 millimeters) Uncrimped Polyester Fiber Percent Tear Burst Fiber F~c~orTensile, Km.FactorDensity, g~cc 0 113 9.73 69.9 0.698 0.2 107 9.66 74.3 0.696 0.5 115 9.60 71.6 0.685 1.0 121 9.54 69.9 0.680 2.5 140 9.23 68.1 0.646 5.0 165 8.20 55.8 0.610 10.0 225 8.00 55.6 0.557 15.0^ 303 7.29 48.9 0.497 20.0 393 6.14 40.7 0.438 25.0 375 .5.52 38.5 0.407 30.0 390 4.83 31.9 0.,374 40.0 452 3.72 24.8 0.333 50.0 332 2.45 18.4 0.277 The tear and tensile results from Table IX have been illustrated in Figures 14 and 15 and it will be seen that tear increases and tensile decreases linearly up to a 25% addition of ;
1 polyester fibers. Tear increases at a lesser rate from 25% up to 40% polyester addition and then shows a sharp decrease. The curve for polyester fiber additions closely approximates the curve for addition of acrylic fibers shown in Figure 3. The poly-ester fiber additions give tear improvements of about 11% for each 1% of polyester fiber added.
Figure 16 is a graph constructed from the data of Table IX showing the tear vs. tensile relationship for the polyester fiber filled sheets and for a control sheet containing no poly-ester fibers.
Table X has been constructed from the data included inTable IX and illustrates tear improvements in polyester filled paper sheets at constant tensile strength. The calculations in-volved in Table X have been arriv~ at in the same manner as ex-plained-in the makeup of the data described above in conjunction with Table VIII.
Table X
EFFICIENCY OF POLYESTER FIBER AT CONSTANT TENSILE
! Ten-sile of Tear of Poly- Control Tear of ester at Poly-Poly- Filled Poly- ester Effi-Kraft, ester, Sheet, ester Filled Change, ciency*, % '` % Km Tens'ile Shee't % %
99.0 1.0 9.54 110 125 13.6 13.64 '' 97.5 2.5 9.23 113 140 23.9 9.56 95.0 5.0 8.20 125 190 52.0 10.40 -'-90.0 10.0 8.00 130 208 60.0 6.00 85.0 15.0 7.29 138 245 77.5 5.17 ' 80.0 20.0 6.14 166 343 106.6 5.33 j 75.0 25.0 5.52 180 375 108.3 4.33 70.0 30.0 4.83 200 408 104.0 3.47 60.0 40.0 3.72 230 452 96.5 2.41 s0.0 50.0 2.45 266 330 24.1 0.48 * % change in tear per percent of synthetic fiber added 1Figure 18 is a graph illustrating the relationship of percentage of polyester fiber added as compared to the percent change in tear for polyester additions over the range of 0% to 15%. It will be noted that a nearly linear change in tear is ! noted up to about 10% addition of the polyester fibers which is quite close to that foundin the data given hereinabove for the addition of acrylic fibers.
Figure 20 is a photo micrograph at about 120 magnifi-cation showing a handsheet from one of the tests given herein-above in Table IX with the amount of polyester fiber addition being 10% and the remainder of the handsheet being made up of 90% of a 570 CSF bleached kraft softwood pulp. The uncrimped nature of the polyester fibers can be clearly seen in Figure 20.
A still further series of test handsheets were made by the same procedure outlined above to determine the optimum amount of aramid fiber to be added to a cellulosic fiber. The uncrimped aramid fiber used was 1/4" (6.35 millimeters) by 1.5 denier and was added to a slightly beaten 570 CSF bleached kraft softwood pulp. The results of the tests are indicated below in Table XI.
$
1 Table XI
STRENGTH PROPERTIES OF ARAMID FILLED HANDSHEETS
1 5 Denier x 1/4" (6.35 millimeters) Uncrimped Aramid Fiber Percent Tear Tear Fiber FactorTensile, Km. Factor Density, g/cc 0 108 9.90 73.1 0.696 0.2 117 10.07 73.1 0.686 0.5 116 9.97 72.6 0.686 1.0 124 10.24 69.2 0.676 2.5 140 9.69 68.4 0.640 5.0 164 8.71 64.1 0.606 10.0 222 7.92 57.3 0.528 15.0 254 6.86 48.7 0.467 20.0 300 5.95 38.7 0.423 25.0 260 5.08 32.6 0.380 30.0 293 4.37 28.1 0.341 40.0 183 2.85 16.2 0.282 50.0 155 1.96 10.4 0.241 ~`
The tear and tensile results from Table XI above have ;
been shown in the graphs of Figures 14 and 15 and it will be noted ~ I
that tear increases and tensile decreases linearly up to about a 20% aramid addition. The tensile continues its linear decrease up through a 50% addition. Above the 20% aramid addition the I tear factor shows a sharp decrease. In the aramid fiber additions ¦ tear increased approximately 7.5% for each 1% of the fiber added up to an addition of about 5% of thearamid fibers.
Figure 17 is a graph constructed from the data of ~able XI showing the tear vs. tensile relationship for the aramid fiber filled sheets and for a control sheet containing no aramid fiber.
;~
} 10910'73 1 Table XII has been constructed from data included in Table XI and illustrates tear improvements in acrylic filled paper sheets at constant tensile strength.
Table XII
EFFICIENCY OF ARAMID FIBER AT CONSTANT TENSILE
Ten-sile Tear of of Tear Aramid Control of Filled at Aramid Effi-10 Kraft,Aramid, Sheet, Aramid Filled Change, ciency*, % % Km._ Tensile Sheet %
99.0 1.0 10.24 101 124 33.8 22.77 97.S 2.5 9.69 106 140 32.1 12.83 95.0 5.0 ~.71 118 179 51.7 10.34 90.0 10.0 7.92 131 215 64.1 6.41 85.0 15.0 6.86 152 252 65.8 4.39 80.0 20.0 5.95 172 274 59.3 2.97 75.0 25.0 5.08 192 288 50.0 2.00 70.0 30.0 4.37 210 293 39.5 1.32 60.0 40.0 2.85 253 205 -19.0 -0.47 50.~ 50.0 1.96 284 155 -45.4 -0.91 * % change in tear per percent of synthetic fiber added Figure 18 also shows the relationship of the percent of aramid fiber added to a composition in relation to the percent change in tear and this has been shown in conjunction with the same curve for the polyester fibers. The graph of Figure 18 covers the range of 0 to 15% fiber addition and it will be noted that a nearly linear change in tear is noted up to about a 5%
additiGn rate of the aramid fibers.
Figure 21 is a photo micrograph at 120 magnification showing a handsheet from one of the tests illustrated in Table XI
with 10% aramid fibers added to 90% of a 570 CSF bleached kraft softwood pulp. This photo micrograph illustrates the physical re-lationship between the cellulose fibers and the aramid fibers in their matted and nonwoven condition and the uncrimped nature of 10910'73 1 the aramid fibers can also be clearly seen from this figure.
Figure 19 is an illustration in graph form which shows the fiber cost per ton in comparison to the increase in tear. In ~A this illustration the fiber costs used were $1.10 per pound for polyester, 58 cents per pound for acrylic, and $9.00 per pound for aramid. In this illustration and assuming these prices it is seen that the aramid fibers do not compare at all with the poly-ester and acrylic fibers on a cost per ton basi and it is noted that the acrylic fibers appear to be more economical than the j 10 polyester fibers on a cost per ton ~asis.
j The polyester fibers give about 1.7 times tear improve-ment over the acrylic fiber for each percent of fiber added and tensile strength losses for the three fibers disclosed herein are substantially equivalent, namely about 1.7% for each 1% of fiber added.
The cellulosic fibers can be produced either by chemi-cal or mechanical pulping processes well known in the industry.
Included in the cellulosic fibers made by the chemical pulping pr~cess are kraft fibers, sulfite fibers, and the like. Included in the cellulosic fibers made by the mechanical pulping processare stone groundwood fibers, refiner groundwood fibers, thermomechani-cal fibers, and the like.-The cellulosic and hydrophilic fibers are entangledwithout apparent bonding therebetweenin the paper sheet and are interrelated by the random dispersing and intermixing of the hy-drophilic fibersin the cellulosic fibers. Preferably the cellu-losic fibers of this invention are fibrillated whereas the hydro-, philic fibers are not fibrillated. This is accomplished in carry-ing out the manufacture of the nonwoven sheet by adding the non-fibrillated hydrophilic fibers to the cellulosic stock after the i 1 cellulosic stock has been fibrillated in the conventional refin-ing and/or beater operation. The mixture of the fibrillated cellulosic fibers and the non-fibrillated hydrophilic fibers are completely free from any extraneous bonding agents other than the medium provided by the fibrillating of the cellulosic fibers which would cause an entanglement of the hydrophilic fibers to the cellulcsic fibers. Note the various hydrophilic fibers in the tests of Tables I, II, III, etc. were~dded after beating of the cellulosic fibers.
While we have illustrated and descrlbed a preferred embodiment of our invention, it will be understood that this is by way of example only and not to be construed as limiting.
In order to determine the optimum amount of acrylic fiber to be added to cellulosic fiber within the teachings of the present invention a series of test handsheets were made by the same procedure outline above with progressively larger amounts of acrylic fiber. The uncrimped acrylic fiber used was 1/4" (6.35 millimeters) x 3.0 denier and was added to a 570 CSF (Canadian Standard Freeness)~ bleached softwove kraft pulp, sold under the ; 1091~73 .
1 trade name of Hibrite pulp. The results of the test are indicated below in Table VII.
Table VII
STRENGTH PROPERTIES OF ACRYLIC FILLED HANDSHEETS
3.0 Denier x 1/4" (6.35 millimeters) Uncrimped Acrylic Fi~er Kraft Acrylic, Tensile, Tear % ~ Km Factor 100 0 10.9 107 10 95 5 9.5 135 8.4 181 7.6 216 6.6 244 5.9 281 5.0 290 3.4 301 2.5 241 The tear and tensile results from Table VII above have been shown in the graphs of Figures 3 and 4 and it will be noted that tear increases and tensile decreases linearly up to a 25%
acrylic addition. Tear increases at a lower rate from 25% up to 40% acrylic addition and then shows a sharp decrease. Tear in-creases over a control (no acrylic addition) at a rate of about 7.3~ for each 1% acrylic added up to a 25% acrylic addition.
Figure 5 is a graph constructed from the date of Table VII showing the tear vs. tensile relationship for the acrylic fi-ber filled sheets and for a control sheet containing no acrylic fiber.
Table VIII has been constructed from data included in Table VII and illustates tear improvements in acrylic filled paper 109~73 .
1 sheets at constant tensile strength. The percent change in tear is calculated by taking the difference between the tear of a con-trol sheet and the tear of an acrylic filled sheet and dividing the difference by the tear of the control sheet. The efficiency is then calculated by dividing the percent change by the percent of acrylic fibers added to the paper sheet.
Table VIII
EFFICIENCY OF ACRYLIC FIBER
Tear of Ten- Control sile Sheet (No Tear of Acrylic Add- of Effici-Acry- ed) at Ten- Acry- % ency, Acry- lic sile of Acry- lic Change ~ Change Kraft, lic Filled lic Filled Filled in %Acrylic % % Sheet Sheet Sheet Tear Added _ 9.~ 110 135 22.7 4.5 ~.4 125 181 44.8 4.5 7.6 135 216 60.0 4.0 6.6 155 244 57.4 2.9 5.9 175 281 60.6 2.4 5.0 195 290 48.7 1.6 3.4 240 301 25.4 0.6 2.5 270 241 -10.7 -0.2 % tear improvement per 1% acrylic fiber added Figure 6 is a graph illustrating these relationships and it will be seen that a constant efficiency is obtained up to about 10% acrylic addition and then a decreased efficiency results as the acrylic fiber in the sheet is increased.
Figures 7-12 are photo micrographs at about 100 magni-fication showing the handsheets from the above tests (Table VII -Figure 3) with varying amounts of acrylic fibers added to the bleached kraft fibers. Figures 7-12 illustrate in visual form the interrelationship between the cellulosic fibers and the acry-lic fibers in their matted nonwov~n condition. ~he Figures 7-12 ~' 1 show respectively 0, 10, 2Q, 30, 40 and 50 percent acrylic con-ditions. The uncrimped nature of the acrylic fibers can also be clearly seen from these figures.
A further series of tests were conducted in a manner similar to those tests discussed above to illustrate the effect in what has been referred to as wet web strength with the re-placement of 5% of the kraft portion of various kraft-groundwood furnishes. The results of these tests are shown in the graph of Figure 13. The groundwood portion of the furnish may be between 20 to 80~ of the total furnish. The wet web strength is common-ly referred to by those skilled in the art and is related to paper making machine runability. It is the work or tensile en-ergy which the wet sheet will absorb at a given stretch, equal to the draw (the speed differential between the wire and the couch~ The wet web strength is attained by integrating the ; stress-strain curve up to a stretch, usually about 3 1/2%, equiv-alent to the draw. The wet web strength values in Figure 13 were obtained at 3'% strain. Figure 13 illustrates clearly the increase in wet web strength for various kraft-groundwood fur-nishes when 5% of the kraft portion of the furnish was replaced with 3/8" (9.6 millimeters)- 3.0 denier uncrimped acrylic fibers.
A test run was made at St. Regis production facilities in Bucksport, Maine. In this run approximateIy 60 english tons of 34 pound letterpress paper containing acrylic and a compar-able amount of control paper from the same pulp, except, without acrylic were made. Comparison tests indicated results similar, or substantially the same as theaforementioned test results set forth herein. In addition the paper was tested in a printing operation on production printing equipment. We found the paper containing acryiic to perform in the printing operation in a man-_ 14 -. i . ~ .
!
1 ner and with results comparable to and the same as the control paper which did not contain acrylic fiber.
In order to determine the optimum amount of polyester fiber to be added to cellulosic fiber a series of test hand sheets were made. The polyester fiber utilized was manufactured by DuPont and was 3/8" (9.6 millimeters) x 3.0 denier and was ' added to a 570 CSF bleached ~raft soft wood pulp. The results of the test are indicated in Table IX.
Table IX
STRENGTH PR~PERTIES OF POLYESTER FILLED HANDSHEETS
3.0 Denier x 3/8" (9.6 millimeters) Uncrimped Polyester Fiber Percent Tear Burst Fiber F~c~orTensile, Km.FactorDensity, g~cc 0 113 9.73 69.9 0.698 0.2 107 9.66 74.3 0.696 0.5 115 9.60 71.6 0.685 1.0 121 9.54 69.9 0.680 2.5 140 9.23 68.1 0.646 5.0 165 8.20 55.8 0.610 10.0 225 8.00 55.6 0.557 15.0^ 303 7.29 48.9 0.497 20.0 393 6.14 40.7 0.438 25.0 375 .5.52 38.5 0.407 30.0 390 4.83 31.9 0.,374 40.0 452 3.72 24.8 0.333 50.0 332 2.45 18.4 0.277 The tear and tensile results from Table IX have been illustrated in Figures 14 and 15 and it will be seen that tear increases and tensile decreases linearly up to a 25% addition of ;
1 polyester fibers. Tear increases at a lesser rate from 25% up to 40% polyester addition and then shows a sharp decrease. The curve for polyester fiber additions closely approximates the curve for addition of acrylic fibers shown in Figure 3. The poly-ester fiber additions give tear improvements of about 11% for each 1% of polyester fiber added.
Figure 16 is a graph constructed from the data of Table IX showing the tear vs. tensile relationship for the polyester fiber filled sheets and for a control sheet containing no poly-ester fibers.
Table X has been constructed from the data included inTable IX and illustrates tear improvements in polyester filled paper sheets at constant tensile strength. The calculations in-volved in Table X have been arriv~ at in the same manner as ex-plained-in the makeup of the data described above in conjunction with Table VIII.
Table X
EFFICIENCY OF POLYESTER FIBER AT CONSTANT TENSILE
! Ten-sile of Tear of Poly- Control Tear of ester at Poly-Poly- Filled Poly- ester Effi-Kraft, ester, Sheet, ester Filled Change, ciency*, % '` % Km Tens'ile Shee't % %
99.0 1.0 9.54 110 125 13.6 13.64 '' 97.5 2.5 9.23 113 140 23.9 9.56 95.0 5.0 8.20 125 190 52.0 10.40 -'-90.0 10.0 8.00 130 208 60.0 6.00 85.0 15.0 7.29 138 245 77.5 5.17 ' 80.0 20.0 6.14 166 343 106.6 5.33 j 75.0 25.0 5.52 180 375 108.3 4.33 70.0 30.0 4.83 200 408 104.0 3.47 60.0 40.0 3.72 230 452 96.5 2.41 s0.0 50.0 2.45 266 330 24.1 0.48 * % change in tear per percent of synthetic fiber added 1Figure 18 is a graph illustrating the relationship of percentage of polyester fiber added as compared to the percent change in tear for polyester additions over the range of 0% to 15%. It will be noted that a nearly linear change in tear is ! noted up to about 10% addition of the polyester fibers which is quite close to that foundin the data given hereinabove for the addition of acrylic fibers.
Figure 20 is a photo micrograph at about 120 magnifi-cation showing a handsheet from one of the tests given herein-above in Table IX with the amount of polyester fiber addition being 10% and the remainder of the handsheet being made up of 90% of a 570 CSF bleached kraft softwood pulp. The uncrimped nature of the polyester fibers can be clearly seen in Figure 20.
A still further series of test handsheets were made by the same procedure outlined above to determine the optimum amount of aramid fiber to be added to a cellulosic fiber. The uncrimped aramid fiber used was 1/4" (6.35 millimeters) by 1.5 denier and was added to a slightly beaten 570 CSF bleached kraft softwood pulp. The results of the tests are indicated below in Table XI.
$
1 Table XI
STRENGTH PROPERTIES OF ARAMID FILLED HANDSHEETS
1 5 Denier x 1/4" (6.35 millimeters) Uncrimped Aramid Fiber Percent Tear Tear Fiber FactorTensile, Km. Factor Density, g/cc 0 108 9.90 73.1 0.696 0.2 117 10.07 73.1 0.686 0.5 116 9.97 72.6 0.686 1.0 124 10.24 69.2 0.676 2.5 140 9.69 68.4 0.640 5.0 164 8.71 64.1 0.606 10.0 222 7.92 57.3 0.528 15.0 254 6.86 48.7 0.467 20.0 300 5.95 38.7 0.423 25.0 260 5.08 32.6 0.380 30.0 293 4.37 28.1 0.341 40.0 183 2.85 16.2 0.282 50.0 155 1.96 10.4 0.241 ~`
The tear and tensile results from Table XI above have ;
been shown in the graphs of Figures 14 and 15 and it will be noted ~ I
that tear increases and tensile decreases linearly up to about a 20% aramid addition. The tensile continues its linear decrease up through a 50% addition. Above the 20% aramid addition the I tear factor shows a sharp decrease. In the aramid fiber additions ¦ tear increased approximately 7.5% for each 1% of the fiber added up to an addition of about 5% of thearamid fibers.
Figure 17 is a graph constructed from the data of ~able XI showing the tear vs. tensile relationship for the aramid fiber filled sheets and for a control sheet containing no aramid fiber.
;~
} 10910'73 1 Table XII has been constructed from data included in Table XI and illustrates tear improvements in acrylic filled paper sheets at constant tensile strength.
Table XII
EFFICIENCY OF ARAMID FIBER AT CONSTANT TENSILE
Ten-sile Tear of of Tear Aramid Control of Filled at Aramid Effi-10 Kraft,Aramid, Sheet, Aramid Filled Change, ciency*, % % Km._ Tensile Sheet %
99.0 1.0 10.24 101 124 33.8 22.77 97.S 2.5 9.69 106 140 32.1 12.83 95.0 5.0 ~.71 118 179 51.7 10.34 90.0 10.0 7.92 131 215 64.1 6.41 85.0 15.0 6.86 152 252 65.8 4.39 80.0 20.0 5.95 172 274 59.3 2.97 75.0 25.0 5.08 192 288 50.0 2.00 70.0 30.0 4.37 210 293 39.5 1.32 60.0 40.0 2.85 253 205 -19.0 -0.47 50.~ 50.0 1.96 284 155 -45.4 -0.91 * % change in tear per percent of synthetic fiber added Figure 18 also shows the relationship of the percent of aramid fiber added to a composition in relation to the percent change in tear and this has been shown in conjunction with the same curve for the polyester fibers. The graph of Figure 18 covers the range of 0 to 15% fiber addition and it will be noted that a nearly linear change in tear is noted up to about a 5%
additiGn rate of the aramid fibers.
Figure 21 is a photo micrograph at 120 magnification showing a handsheet from one of the tests illustrated in Table XI
with 10% aramid fibers added to 90% of a 570 CSF bleached kraft softwood pulp. This photo micrograph illustrates the physical re-lationship between the cellulose fibers and the aramid fibers in their matted and nonwoven condition and the uncrimped nature of 10910'73 1 the aramid fibers can also be clearly seen from this figure.
Figure 19 is an illustration in graph form which shows the fiber cost per ton in comparison to the increase in tear. In ~A this illustration the fiber costs used were $1.10 per pound for polyester, 58 cents per pound for acrylic, and $9.00 per pound for aramid. In this illustration and assuming these prices it is seen that the aramid fibers do not compare at all with the poly-ester and acrylic fibers on a cost per ton basi and it is noted that the acrylic fibers appear to be more economical than the j 10 polyester fibers on a cost per ton ~asis.
j The polyester fibers give about 1.7 times tear improve-ment over the acrylic fiber for each percent of fiber added and tensile strength losses for the three fibers disclosed herein are substantially equivalent, namely about 1.7% for each 1% of fiber added.
The cellulosic fibers can be produced either by chemi-cal or mechanical pulping processes well known in the industry.
Included in the cellulosic fibers made by the chemical pulping pr~cess are kraft fibers, sulfite fibers, and the like. Included in the cellulosic fibers made by the mechanical pulping processare stone groundwood fibers, refiner groundwood fibers, thermomechani-cal fibers, and the like.-The cellulosic and hydrophilic fibers are entangledwithout apparent bonding therebetweenin the paper sheet and are interrelated by the random dispersing and intermixing of the hy-drophilic fibersin the cellulosic fibers. Preferably the cellu-losic fibers of this invention are fibrillated whereas the hydro-, philic fibers are not fibrillated. This is accomplished in carry-ing out the manufacture of the nonwoven sheet by adding the non-fibrillated hydrophilic fibers to the cellulosic stock after the i 1 cellulosic stock has been fibrillated in the conventional refin-ing and/or beater operation. The mixture of the fibrillated cellulosic fibers and the non-fibrillated hydrophilic fibers are completely free from any extraneous bonding agents other than the medium provided by the fibrillating of the cellulosic fibers which would cause an entanglement of the hydrophilic fibers to the cellulcsic fibers. Note the various hydrophilic fibers in the tests of Tables I, II, III, etc. were~dded after beating of the cellulosic fibers.
While we have illustrated and descrlbed a preferred embodiment of our invention, it will be understood that this is by way of example only and not to be construed as limiting.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A non-woven paper sheet having a basis weight of not more than 35 pounds per 3300 square feet including in com-bination cellulosic fibers intermixed with non-fibrillated hy-drophilic fibers and being free of binder, said hydrophilic fibers being present in an amount in the range of from 0.2% to 10% by weight of the total weight of the paper sheet and being effective to substantially increase the tear strength of the paper sheet, said hydrophilic fibers being between 1/8 and 1/2 inch in length, and between 1.5 and 6.0 denier and are relatively straight and uncrimped, said cellulosic fibers comprising kraft pulp and mechanical pulp, said mechanical pulp being present in an amount in the range of from 20% to 80% of the total cellulo-sic fiber weight.
2. A non-woven paper sheet as claimed in claim 1 in which the hydrophilic fibers are acrylic fibers and are present in an amount in the range of from 0.2% to 10% by weight of the total weight of the paper sheet.
3. A non-woven paper sheet as claimed in claim 1 in which the hydrophilic fibers are polyester fibers and are pre-sent in an amount in the range of from 0.5% to 5% by weight of the total weight of the paper sheet.
4. A non-woven paper sheet as claimed in Claim 1 in which the hydrophilic fibers are aramid fibers and are pre-sent in an amount in the range of from 0.2% to 5% by weight of the total weight of the paper sheet.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US83185677A | 1977-09-09 | 1977-09-09 | |
| US831,856 | 1977-09-09 | ||
| US90575778A | 1978-05-15 | 1978-05-15 | |
| US905,757 | 1978-05-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1091073A true CA1091073A (en) | 1980-12-09 |
Family
ID=27125471
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA309,601A Expired CA1091073A (en) | 1977-09-09 | 1978-08-17 | Paper composition |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5450604A (en) |
| AU (1) | AU3949078A (en) |
| CA (1) | CA1091073A (en) |
| FI (1) | FI782585A (en) |
| FR (1) | FR2402740A1 (en) |
| GB (1) | GB2003953A (en) |
| IT (1) | IT1098822B (en) |
| NZ (1) | NZ188123A (en) |
| SE (1) | SE7809437L (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4755421A (en) * | 1987-08-07 | 1988-07-05 | James River Corporation Of Virginia | Hydroentangled disintegratable fabric |
| US4902564A (en) * | 1988-02-03 | 1990-02-20 | James River Corporation Of Virginia | Highly absorbent nonwoven fabric |
| US5223095A (en) * | 1991-01-23 | 1993-06-29 | Custom Papers Group Inc. | High tear strength, high tensile strength paper |
| WO2000040092A1 (en) * | 1999-01-05 | 2000-07-13 | Dexter Speciality Materials, Ltd. | Paper and related products of improved wet expansion profile |
| CN115075041B (en) * | 2022-05-18 | 2023-06-20 | 华南理工大学 | High-air-permeability paper bag paper and preparation method and application thereof |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1198190A (en) * | 1958-06-06 | 1959-12-04 | Papeteries De France | Tear-resistant paper and how it is made |
| US3028296A (en) * | 1958-10-20 | 1962-04-03 | American Can Co | Fibrous sheet material |
| US3489643A (en) * | 1966-04-18 | 1970-01-13 | Dexter Corp | Sheet material of improved tear strength including long undrawn polyamide fibers |
| GB1276329A (en) * | 1968-09-03 | 1972-06-01 | Eastman Kodak Co | Paper product incorporating fibrous polyester material |
| GB1408175A (en) * | 1971-11-20 | 1975-10-01 | Mitsubishi Rayon Co | Acrylic fibrous material and sheet made therefrom and process for manufacturing same |
-
1978
- 1978-08-11 NZ NZ188123A patent/NZ188123A/en unknown
- 1978-08-17 CA CA309,601A patent/CA1091073A/en not_active Expired
- 1978-08-22 GB GB7834151A patent/GB2003953A/en not_active Withdrawn
- 1978-08-24 FI FI782585A patent/FI782585A/en not_active Application Discontinuation
- 1978-09-01 AU AU39490/78A patent/AU3949078A/en active Pending
- 1978-09-06 JP JP10867378A patent/JPS5450604A/en active Pending
- 1978-09-07 IT IT27425/78A patent/IT1098822B/en active
- 1978-09-07 SE SE7809437A patent/SE7809437L/en unknown
- 1978-09-08 FR FR7825902A patent/FR2402740A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| FR2402740A1 (en) | 1979-04-06 |
| FI782585A (en) | 1979-03-10 |
| IT1098822B (en) | 1985-09-18 |
| IT7827425A0 (en) | 1978-09-07 |
| SE7809437L (en) | 1979-03-10 |
| GB2003953A (en) | 1979-03-21 |
| AU3949078A (en) | 1980-03-06 |
| NZ188123A (en) | 1981-02-11 |
| JPS5450604A (en) | 1979-04-20 |
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