MXPA01003010A - A sanitary paper product made by modifying coarse fibers and process thereof - Google Patents

Abstract

A method of making sanitary paper products from coarse fibers. The method includes the steps of:(a) pulping coarse fibers in water with agitation to produce a pulp slurry, the pulp from the coarse fibers having an average fines content of greater than about 40%;(b) using an effective amount of pulp washing to reduce the fines content and increase the Canadian Standard Freeness;(c) introducing the pulp at a papermaking consistency into the headbox of a paper making machine;and (d) utilizing the pulp in a paper making process to produce sanitary paper products.

Description

A SANITARY PAPER PRODUCT MADE THROUGH THE MODIFICATION OF HARD FIBERS AND PROCESS FOR THE SAME BACKGROUND OF THE INVENTION Typically in papermaking, there is a general correlation between the roughness of the fiber and the softness or feel of the resulting paper product High-quality fibers such as bleached soft northern fibr kraft are thin and flexible and are used to produce desirable and soft tissue products. Conversely, the mechanical pulp reduction of softwoods produces rigid, harsh high-performance fibers. Typically used to make newspaper Generally, newspaper papers contain high-performance, mainly rough fibers, typically stone-ground wood (SG), thermomechanical pulp (TMP) and quimotermomechanical pulp fibers (CTMP). Such rough newspaper fibers are usually highly refined to cause fractures and fibrillations which help impart strength to the resulting newspaper. Such refinement changes the freedom of the harsh fiber fiber from a "high liberty" to "low freedom" fibers. If such fibers mechanically reduced to pulp, rough, high performance and refined were used in a tissue product the resulting sheet would not be soft, and therefore, more likely would be undesirable as a tissue product.

A complete discussion of the relationship between the softness of the tissue and the roughness of the fiber is contained in Canadian Patent 2,076,615. Attempts to produce towel-type or soft tissue-type sanitary paper products of a majority of high-yielding harsh fibers, such as quimotermomechanical pulp, thermomechanical pulp, or stone-ground wood have not been successful. Similarly, the production of soft towel and tissue products through the recycling of old paper newspapers has not been very successful partly because the predominant fibers have little freedom, are rough, and have relatively high fines levels.

Other complicating factors in the production of towel products and soft tissues of recycled newspaper are the problems with the operation of the paper machine due to the poor drainage of the fibers of low freedom to the problems with the fines and other substances that it accumulates in the water system of the paper machine (white water) These materials make the creping of the Yankee dryer cylinder sheet difficult, and therefore they require operating the paper machine at conditions which do not promote smoothness. maximum.

There is an unmet need and a long-time perception of a soft paper product made of harsh high-performance fibers from sources such as recycled newspaper. There is also a need for an economical and practical process to treat the harsh fibers of high performance recycled newspaper so that these are suitable for making soft paper products. This need also extends to a process for treating the periodic paper and / or printing fibers so that they are suitable for making soft paper products as well as for making soft paper products containing such treated fibers.

DEFINITIONS As used herein, the term "comprises" refers to a part or parts of a whole, but does not exclude other parts. That is, the term "comprises" is an open language that requires the presence of the recited element or structure or its equivalent, but does not exclude the presence of other elements or structures. The term "includes" has the same meaning and is interchangeable with the terms "includes and" has ".

The term "machine direction" as used herein refers to the direction of travel of the forming surface on which the fibers are deposited during the formation of a material.

The term "cross machine direction" as used herein refers to the direction in the same plane which is perpendicular to the machine direction.

As used herein, the term "cellulose" refers to a higher polymer of natural carbohydrate (polysaccharide) which has the chemical formula (C5H10Os) __ and which consists of d anhydroglucose units linked by an oxygen bond to form long molecular chains that they are essentially linear. The natural sources of cellulose include coniferous deciduous trees, cotton, flax, esparto grass, vendetósigo, straw, hemp jute and bagasse.

As used herein, the term "pulp" refers to cellulose processed by such treatments such as, for example, thermal, chemical and / or mechanical treatments.

As used herein, the term "roughness" is the weight per unit fiber length, expressed with milligrams per 10 meters typically, a fiber is considered rough having a value greater than about 12 milligrams per 100 meters.

SYNTHESIS OF THE INVENTION The present invention relates to the needs described above by providing a method for modifying a source of rough high yield type pulp such as recycled newspaper into suitable pulps for making soft tissue type products. According to the present invention, the pulp of high performance type d low and rough freedom found in the printing paper (for example in newspaper papers) can be modified to produce soft tissue products by washing the pulp to reduce the proportion fine in the pulp.

The method for making sanitary fiber paper products includes the steps of: (a) pulping the rough fiber in the water with agitation to produce a pulp solution, the pulp of the harsh fibers has an average fines content of more than about 40 percent (b) use an effective amount of pulp wash to reduce fine content and increase Canadian Standard Freedom (c) introducing the pulp to a papermaking consistency and paper inside the headbox of a papermaking machine; and (d) using the pulp in a paper manufacturing process to produce sanitary paper products.

An effective amount of pulp washing can reduce the fine content to less than about 35 percent and increase the Canadian Standard Freedom p more than about 50. The pulp can be fed into a papermaking machine at a consistency of manufacturing to make paper varying from about 1.0 percent around 0.01 percent.

The present invention encompasses the method described above wherein the sanitary paper product made using the pulp is a tissue paper made at a basis weight of between 7 and 3 pounds per ream. The toilet paper product can also be a paper towel made at a basis weight of between 12 and 4 pounds per ream. The sanitary paper product can also be a paper napkin made at a basis weight of between and 35 pounds per ream.

Generally, the pulp may be composed of at least 60 percent cellulose fibers of which are rough fibers having a Kajaani roughness greater than 1 milligrams per meter. For example, the pulp may be composed of at least 60 percent recycled newspaper fibers having a Kajaani roughness greater than 1 milligram per 100 meters.

Pulp from other sources such as recycled newspaper papers can have a fine average content of more than about 40 percent before treatment. For example, the pulp can have a fine average d content more than about 46 percent before treatment. As another example, the pulp may have a higher average fine content of about 48 percent before treatment.

Pulp from sources such as recycled newspaper can have a Canadian Standard Freedom of less than about 300 before treatment. For example, the pulp 'can have a Canadian Standard Freedom of less than about 270 before treatment. As another example, the pulp can have a Canadian Standard Freedom of less than about 200 before treatment.

According to the invention, the pulp from sources such as recycled newspaper is washed so that the content of fines is reduced to less than about 3 percent. For example, the pulp is washed so that the fine content is reduced to less than about 3 percent. As another example, the pulp is washed so that the fine content is reduced to less than about 2 percent.

In one aspect of the invention, the pulp of the fuent such as the recycled newspaper is washed so that Canadian Standard Freedom is increased by more than about 50. For example, the pulp is washed so that the Canadian Standard Libert is augmented by more than about 70 As another example, the pulp is washed so that the Canadian Standard Libert is augmented by more than about 90.

The present invention also encompasses a method for modifying recycled newspaper pulp to improve its tissue and towel making properties. The method to modify the pulp of recycled newspaper includes the steps of: (a) pulping the newspaper in water co-agitation to produce a pulp solution, the pulp of the periodic paper has an average fine content of more d around of 40 percent; (b) use an effective amount of pulp wash to reduce the fine content and increase the Canadian Standard Freedom; and (e) introducing the pulp to a papermaking consistency inside the headbox of the papermaking machine so that the pulp can be used in the papermaking process to produce sanitary paper products.

An effective amount of pulp washing can reduce the fine content to less than about 3 percent and increase the Canadian Standard Freedom by more than about 50. The pulp can be fed into the machine to make paper at a consistency to make paper varying from about 1.0 percent to about 0.01 percent.

An embodiment of the present invention encompasses a method of modifying the pulp of recycled newspaper which includes the steps of: (a) pulping the periodic paper in shaking water to produce a pulp solution; and (b) introducing the pulp to a papermaking consistency in the headbox of the paper making machine, the pulp having a fine content of less than about 3 percent and a Canadian Standard Freedom of more than about 300 so that the pulp can be used in a papermaking process to produce sanitary paper products.

Another embodiment of the present invention includes a sanitary paper product having modified fibers of rough fibers. The product has a fine content reduced to less than about 40 percent and an increased Canadian Standard Freedom of more than around 250 d.

DESCRIPTION OF THE INVENTION AND OF THE PREFERRED INCORPORATION Generally, the present invention provides a process for treating a high yielding rough fiber pulp of recycled newsprint which contains a relatively high fines content and has a relatively low Canadian Freedom. According to the invention, this relatively low quality pulp can be treated so that it can be used to make soft paper products.

The present invention is based on the discovery that the recycled newspaper pulp can be modified to produce soft tissue type products which have qualities comparable to the tissue products made of softwood kraft fibers from the bleached north. Generally the recycled newsprint pulp is composed of harsh high performance type fibers (eg fibers produced by a predominantly mechanical separation of the wood fibers and typically containing at least 60 percent po weight of the source material). These cellulose fibers it includes high-harshness fibers that have a roughness of more than 1 milligrams per 100 meters. The pulp of recycled newspaper typically contains fines at a level greater than about 4 percent and has a CSF of less than about 300. Such a low quality pulp can be used to produce soft tissue tip products if treated by the using an effective amount of pulp washing so that the fine content decreases less than about 35 percent and the CSF content increases by more than about 50.

Generally, harsh fibers from sources such as recycled newspaper are reduced to pulp using conventional techniques. However, special cleaning and fiber preparation and / or deinking techniques are contemplated.

For example, recycled newspaper can be converted to a solution at a consistency of about 3 percent and 18 percent and at a temperature d between about 100 ° F and 180 ° F. This can be followed by adjusting the pH and reducing the temperature of the pulp solution at a suitable temperature and pH to open and swell the fiber. The pH of the pulp solution can be less than about 8 (even though alkaline conditions can be used). Desirably, the pH can be between about 7 and a temperature below about 150 ° F preferably above about 100 ° F.

After the solution is reduced to pulp, the solution is dewatered to a consistency of about 1 percent to about 35 percent. A device for carrying out the "drain" operation described herein in relation to the present invention can be obtained from Voit Sulser Paper Technology, of Appleton Wisconsin. Other suitable devices will be evident to those skilled in the art.

After the pulp is drained, this can be made crumbs to control the size of the fibers crumbs. Generally, the conversion to crumbs is not normally necessary with the pulp of recycled newspaper. device for carrying out the "crumb conversion" operation described herein in connection with the present invention can be obtained from Scott Equipment Company, of New Prague Minnesota. Other suitable devices will be apparent to those skilled in the art.

The method for practicing the present invention when starting with the newspaper used consists largely of: (1) pulping the newspaper by means of making the newspaper papers in water in a solution; (2) wash the pulp to remove fines and increase freedom; and (3) using the pulp in solution as part of supply in a sanitary papermaking process preferably a papermaking process.

The solution is carried in several stages starting with making a solution of old printing paper or newspaper paper, at a consistency of between about percent and 18 percent, preferably at a temperature of the pulp solution above about 100 ° F and keeping it at elevated temperature for at least about 15 minutes This is followed by reducing the temperature of the pulp solution to a temperature. Desirably, the pulp is maintained at a pH of 4 to 7 and at a temperature below about 140 ° F, preferably elevated above about 100 ° F.

Desirably, the pulp reduction process involves pulping the old periodic papers to 6-percent consistency and at an elevated temperature with a range of about 100 ° F-180 ° F. The pulp reduction time can vary from 15-60 minutes. The solution is then cooled to 100 ° F-150 ° F and transferred to a retention bin-mix box where the pH can be adjusted to a pH of between 4 and 7 and allowed to settle, desirably po around 30 minutes.

The pulp is then washed to remove the fines and increase freedom. Conventional washing techniques can be used until a sufficient amount of fines has been removed and an increase in freedom has been achieved.

After the washing step, the pulp will then be ready for the papermaking process. Further screening is not necessary even when screening and / or centrifugal cleaning can be practiced to remove large contaminants, eg, paper clips, to protect paper machine. Optionally, the free float and the dissolved material can be washed out of the paper making machine that forms the fabric and removed from the white water of the papermaking machine by using a flotation step for the removal of contaminants from the white water of the machine to make paper. This can be done by using a grid side of the hill and a dissolved air flotation process, such as a Krofta classifier, to clarify the white water for reuse in the paper making machine.

Although the inventors do not wish to rely on a particular theory of operation, it is thought that washing helped to produce softer paper products by removing the fines and other pulp components (e.g., small particles) which have a tendency to reduce the freedom of a sample of pulp.

The softness is difficult to measure or quantify for the tissue products because the softness is typically perceived by the feel of the hand which is influenced by the smoothness and other surface characteristics in addition to the foaming of the sheet. The hand sensation tests have been developed and the hand sensation data have been reported here and have generally been obtained according to the following test.

TEST OF SENSATION OF THE HAND REACH Several lightweight and different dry creping tissues were purchased for use as standards or these were produced from commercially available pulp of different qualities to impart softness to the tissue products. These tissues were used to define a scale of numerical softness. A numerical value was assigned to the softness of each standard of tissue.

The softest product manufactured from the commercially available pulp was assigned a hand sensation value of 86, and was a dry-creased tissue of liger weight produced with 50 percent of softwood Kraft fibers.

North Irving and 50 percent of Kraft eucalyptus pulp from Sant Faith. The roughest product to be used as a standard was produced with 100 percent quimotermomechanical pulp of soft 100 percent bleached mader (SWCTMP) and assigned a hand sensation value of 20 on the scale. Other samples of crepe and dry lightweight tissue were produced to be used as standards to define the scale of "softness of the hand sensation" and which have softness qualities between the softer and rougher tissue standard of different pulps or d pulp mixtures were assigned values of softness and hand feeling between 20 and 86. The pulps used are more described in the following paragraphs. The tissue manufacturing process other than the dry creping process of lightweight and other pulp fibers other than those used to produce the standards are capable of producing tis products outside the softness scale of hand feel of 20 86 by the tissue standards described here. However, for the purposes of establishing the improvement in softness that can be achieved with the present invention, the range of hand feel softness defined above from 20 to 8 for light weight dry creping products is accurate enough for comparative The recycled newspaper fibers of the present invention can produce tissue products having softness values greater than 8 when used in another tissue manufacturing process such as the continuous drying process or when mixed with other fibers.

PULPES USED TO PRODUCE HAND SENSING STANDARDS (a) The quimotermomechanical pulp of blanched bleached wood (SWCTMP) (Temcell 500/80 class) having a Canadian Standard Free (CSF) of 500 and an ISO brightness of 80 s made from black spruce and balsamer. The reduction to pulp was co pretreatment of sodium sulfite and a pressurized refinement followed by bleaching with alkaline peroxide at 80 ° ISO brightness. The Kajaani roughness of the fibers was 27.8 milligrams per 100 meters and the Kajaani average fiber length was 1.7 millimeters. (b) The Softwood Kraft of the North Blanquea (NSWK) (Pictou class 100 / 0-100 percent softwood) was made black and balsamer spruce. The reduction to pulp was by the Kraft process for Kappa # = 28 followed by the whitened CE.DED 88 ° ISO brightness. The Kajaani roughness equaled 14, milligrams per 100 meters and the average fiber length of Kajaani was 2.2 millimeters. (c) Bleached recycled fiber (RF) was blended and classified office waste that was pulped, screened, cleaned and washed at 550 ° of Canadian Standard Freedom followed by bleaching with 80 ° ISO sodium hypochlorite. of brilliance. The Kajaani roughness equaled 12, milligrams per 100 meters and the average fiber length of Kajaani was 7.2 millimeters. (d) Bleached eucalyptus kraft pulp (BEK (Santa Fe elemental chlorine free class) was made from eucalyptus Globulus reduced to pulp at Kappa # = 12 by the kraf process followed by bleaching ODE0DED at an ISO brightness of 89 ° The Kajaani roughness was equal to 6.8 milligrams per 100 meters the average fiber length of Kajaani weight was 0, millimeters (e) Southern soft white wood kraft (SSWK) (Pine Mobile Scott) was made of Loblolly pine and slashed pineapple and pulped to Kappa # 26 followed by blanched CEHED at an ISO brightness of 86 °. The Kajaani roughness was equal to 27.8 milligrams per 100 meters and the Kajaani average fiber weight length was 2.6 millimeters. (f) The quimotermomechanical pulp of bleached wood (HWCTMP) (Millar Western 450/83/100 class) had a Canadian Standard Freedom (CSF) of 450 and an ISO brightness of 83 was made of aspen. The reduction to pulp was co pre-treatment of alkaline peroxide and a pressurized refinement followed by bleaching with alkaline peroxide. The Kajaani roughness of the fibers was equal to 13.8 milligrams per 100 meters and the fiber length by means of Kajaani weight was 0.85 millimeters.

APPARATUS The test method does not require a device. The test method used the procedures and materials described below to evaluate the tissue samples using a panel of 10 or more people and a range of sample softness on a scale of softness using the product standards known softness scale values . Some samples were tested by a certified tester using product standards of known softness scale values. The results of the certified tester are identified where it is used instead of a test panel.

SAMPLE PREPARATION 1. Five samples must be selected to be tested by the panel of assessors (judges). 2. Calculate the number of sample pads and standard sample pads needed for the panel of test judges for each product so that it is evaluated for smoothness using the following equation: Necessary pads (each product) = (x-1) x (and x = number of products that are going to be tested y = number of people on the test panel 3. Select at random a roll of sample tissue for each product that is being evaluated and discard the first few sheets (to get rid of the adhesive that binds tail).

Prepare the sample pads of each product roll that is being tested. Each pad should be 4 sheets thick and made from a sample of tissue that is 4 sheets long. Each pad is made as follows the sample of 4 sheets long is first folded to the mita This results in a sample of double thickness of two sheets d long. The double thickness sample is then bent again in half to produce a sample pad of a single long sheet and 4 sheets thick. The pad should be made so that the outer surface of the sheets when it is on the tissue roll becomes the outer surface of the pad. If a product of "two sides" is going to be tested, this is this has different surface characteristics on the outer surface of the sheet against the surface facing the inside of the roll then the product must be tested twice, once with the outside surface of the roll as the outer surface of the sample of the pad and also be tested with a separate sample pad prepared in which the bending results in the sheet surface facing the inside of the roll becoming the surface outside of the sample pad. 4. Make the required number of pads for each product using the formula in paragraph 2 above. If more than one roll of product is needed to prepare the required number of pads, then it is important that the stacks of pads are randomized with product from each of the rolls. Encode each pad with the loading code in the upper left-hand corner (over the fold) . Select 3 standards that are going to be used as references by the panel among the standard tissues as follows: Select the roughest sample that has been evaluated and compare it with the standard tis sample pads and select a lower standard that is slightly rougher than the rougher sample.

Select the softest sample of product that is being evaluated and select a standard tis pad that is slightly higher (softer) than the softer pad that is being evaluated.

Select a third standard which falls to approximately half of the selected standards and lower level.

The three tissue pads that are selected become the handshake references for the panel and define the softest, roughest, and midrange. 6. The references of hand feeling frames the range of softness of the products that are being evaluated by the panel. For greater accuracy, the highest and lowest references selected should be approximately 30 points apart on the hand-feeling softness scale. The average reference should be at 8 or more points of separation from the lower or upper references.

SELECTION AND INSTRUCTION OF THE PANEL MEMBER 1. Select a panel of about 1 people who have about the same number of males and d females and with age variations. 2. Make sure that the members of the panel understand the instructions and if necessary make a "trial run". 3. The panels must be carried out in a quiet place.

Test Procedures 1. Begin the softness test by reading the following standard instructions.

STANDARD INSTRUCTIONS These instructions will be read to the participant of the panel before beginning the procedure of testing the softness panel.

PURPOSE "The purpose of this procedure is to compare the softness of the tissue samples for the toilet." b. METHOD "You will be given two toilet tissue pads each time, compare the two with each other using your dominant hand and making the comparison by perceiving each sample with your dominant hand. You can caress, bend or crease the samples as you considered it appropriate to make your judgment "c. FIRST DECISION "After feeling each of the two pairs of pads samples, you are asked to decide which sample is the softest" d. SECOND DECISION "Rate the degree of difference and smoothness between the two pads using the following rating: The scale uses odd numbers 1,3,5,7,9. You can use the even numbers if you feel that the numbers listed do not completely represent the difference between the products " PANEL RATING SCALE The numbers on the rating scale are defined as: No difference 3. Very small difference, not reliable, some may not perceive it . Small, reliable difference about the juic 7. Moderate difference, easy to detect reliably 9. Very big difference, very easy to detect memorable and. CALIBRATION "Before we begin, I will give you an example of a softer standard that will be used for comparison and a sample pad of less soft products (rougher standard) .Please manipulate both.You will rate the difference in softness that you You will feel between the standard references on the definition scale as 9"(e 9 on the rating scale is the equivalent of the number d hand feeling points on the softness scale of the upper and lower reference selected for the panel e step 5) f. PARTICIPANT REACTION "Do you have any questions about the test procedure?" g. PROMISE OF CONFIDENCE "Finally, do not worry too much about the decision, your opinion is as good as any other's. There are no right or wrong answers!" 2. Present each combination of sample pads and reference pads to each bread member and ask them to select the preferred sample and then rate the difference using the rating softness scale from 1 to 9. Each panel member should receive the pairs randomly at order to avoid errors in sequence. 3. Record results of each pair as XYn. E where X is the preferred sample code, Y is the non-preferred sample code and n is the scale value (1 to 9).

Analysis of data The comparison results in pairs are treated as if they belonged to a rating scale. The definition of a rating scale is given as follows: U scale is a proportion of scales and the scale is invariant under positive linear transformations of the form y = x1a > 0 The data of pairs and the proportion of weights pa "n" number of pads are loaded in a square matrix To the following formula or_. oN 0? x x x w_ W2Wn w2 2w2 w_w2wn wn wn n Wx W2Wn Where Ox is the individual samples and W1 is the scale values (proportion weights) for each pair.

For square matrices of this type there is the following property.

AW = MW Where W = (Wx, W2 ... Wn). The weight vector is the eigenvector of matrix A corresponding to its own value n. Saaty has shown (from Saaty, TL, "A Scalar Method Priorities in Hierarchical Structures", Journal of Mathematical Psychology, 15,234-281 (1977) and Saaty, TL "Midiend the Fluff of Games", Journal of Cybernetics, 4 (4) 53-61 (1974)) that the extract of the vector W proper of the estimated weight requires finding the largest eigenvalue of A (max). A computer program to solve if by the sign max and W is provided in McConnell, Wes, "Product Development using puffed games" INDA Tenth Technical Symposium, page 55-72, November 17-19, 1982. Own vector resultant W is the best estimated ratio scale of the inputs and pairs. Taking the log of each element in this vector, we create the most familiar equal interval scale in which the distance between the objects is linear. The standard softness values are plotted against the estimated equal interval scale values and the unknown samples are assigned numerical values by interpolation.

The standard and standard deviation of the standard softness values of each unknown sample were calculated from the standard softness values calculated for all panel members. If any single pane member value falls outside the two standard deviations of the medium, the value is discarded and the mean and standard deviation s recalculate. The mean of the softness values set without values outside of 2 standard deviations of the medium is the standard hand softness value for the unknown sample.

SCALE OF SOFTNESS OF SENSATION 20 30 40 50 60 70 80 90 20 86 Oj) (3b) Resistance to stress The strength values given herein for the tissue-type paper products are measured by a breaking length test (TAPPI test method T494om-88 using a 5.08 cm sample space and a crosshead velocity of 5, 08 centimeters per minute Typically the tissue resistances are different in the machine direction against the direction transverse to the sheet machine, also the base weight of the tissue samples will vary which affects the tensile strength. to better compare the tensile strengths of several tissue samples, to compensate for the differences in the base weight of the samples and for the differences in the direction of the resistance machine. to the tension. The compensation is achieved by calculating a "basis weight and directional stress resistance normalized" hereinafter "Resistance Normalized Tension" or "NTS"). The resistance to the normalized tension is calculated as the quotient obtained by dividing the base weight in the square root of the product of the resistance to the machine direction and in the cross direction to the machine. The stress resistance calculations normalized for differences in base weights in the machine direction have been designed for better comparisons of the tissue samples. The tensile strengths are measured in both the machine direction and the transverse direction to the machine and the basis weight for the tissue sample measured according to the TAPPI test method No. T-410om-88. When the English measurement units are used, tensile strength is measured in ounces per inch and base weight in pound per ream (2880 square feet). When calculated in metric units, the tensile strength is measured in grams per 2.5 centimeters and the basis weight is measured in grams per square meter. It should be noted that the metric units are not pure metric units because the pressing apparatus for the tensile strength was set to cut a sample and inches and therefore the metric units come to be gram by 2.54 centimeters. Using the abbreviations MDT for tension in the direction of the machine, CDT for tension in the direction transversal to the machine and VW for base weight, the mathematical calculation of the basis weight and of the resistance to the directionally normalized tension (NTS) is: NTS = (MDT x CDT) 12 / BW The directional stress resistance normalized in English units = 0.060 x the directional stress resistance normalized in the metric units defined above.

FINE The level of fines in the pulp sample is based on the determination of fiber length or particle length. The "average fiber length" refers to a heavy average length of pulp fibers determined using a Kajaani fiber analyzer model No FS-100 available from Kajaani Oy Electronics, of Kajaani Finland. According to the test procedure, a pulp sample is treated with a macerating liquid to ensure that no bunches or fiber cuttings are present. Each sample of pulp is disintegrated in hot water and diluted to a solution of approximately 0.001 percent. Individual test samples are drawn in portions of approximately 50 100 milliliters of the diluted solution when tested using the standard Kajaani fiber analysis test procedure. The average heavy fiber length can be expressed by the following equation: k S (xx * ri / n x, = 0 Where k = maximum fiber length xx = fiber length nx = number of fibers that have length X1 n = total number of fibers measured "Low average fiber length pulp refers to the pulp and process byproducts for making paper that contains a significant amount of short fibers of non-fiber particles." In many cases, these materials can be difficult to form in sheets of paper can give relatively tight paper sheets and waterproof or non-woven fabrics.The pulps of low average fiber length can have an average fiber length of less than d about 1.2 millimeters as determined by analyzer of fiber optic such as, for example, a Kajaani Fiber analyzed model No. FS-100 (Kajaani Oy Electronics, d Kajaani, Finland) For example, pulp lengths of low average fiber can have an average fibr length that varies from about 0.6 to 1.2 millimeters.

Generally, most of the fibrous cellulose components of the papermaking solution can be considered pulp of low average fiber length (short fibers non-fiber particles). In many cases, the fibrous cellulosic compound may be a pulp of low average fiber length that contains more than 40 percent "fines" (eg, fiber-type particles of about 0, millimeters or less in length) as I determine by a fiber optic analyzer such as, for example, a Kajaani fiber analysis model No. FS-100 (Kajaani Oy Electronics, Kajaani Finland).

FREEDOM Freedom is a measure of the rate at which a diluted suspension of pulp can be drained. The freedom was measured using a Canadiens Standard Freedom tester essentially in accordance with the TAOOI R 227 m-58 standard and the CPP Standard C.l, (1952). using procedures for samples of ground wood pulp. The Canadian Standard Freedom tester is available from Testing Machines, Inc. of Amityville, New York.

PROCESS TO MAKE TISU The washed pulp of recycled newspaper produced by the process of the present invention can be used in any common papermaking process to produce soft, bulky tissues of sanitary paper such as tissue, towel, napkins and facial tissue. Many processes for making different paper are suitable including those processes in which the fabric is dried through a canister of drying, continuous drying, thermal drying combinations thereof.

Examples of the types of papermaking processes which may be used in conjunction with the present invention are those processes taught in United States of America patents No. 3,301,746 granted to Sanford others; 3,821,068 granted to Shaw; 3,812,000 granted to Salvucc and others; 3,994,771 issued to Morgan Jr. and others; 4,102.73 granted to Morton; 4,158,594 issued to Becker et al .; 4,440.59 granted to Wells and others; and 5,048,589 issued to Cook and others.

The preferred papermaking process commonly known as the dry creping process generally involves using the paper supply of the present invention to which dry strength chemicals are preferably added to generate a tensile strength and other aggregates can be added. manufacturing chemicals paper. The paper supply is then pumped from a machine chest and flowed to a headbox where the surfactant system was added. Then the paper supply flows through a slice to a consistency of 0.1 to 0. percent on a horizontal surface of a Fourdrinier wire through which water is removed and tissue formation occurs. The wire cloth is carried around a breast roller and several table rollers, then the wire overturning roller from which it is fed around a bed roll and several guide rollers back to the breast roller. One of the rollers is driven to drive the Fourdrinier wire. One or more vacuum boxes (reflectors or hydroblades) can be used between the table rollers to increase water removal.

The wet fabric is formed on the upper surface of the Fourdrinier and is transferred to a felt by pressing the fabric onto the felt by means of a bed roll or transferring the sheet to the felt by means of a pick-up shoe. The felt transports the fabric to a pressure set. The felt then moves about 1 or 2 of the press rolls, one of which may be a suction roll, and then carried around the guide rolls rotates back to the bed roll. The showers and protection boards can be used in various positions on the felt surface to assist in a clean-up of fabric collection and conditioning of the felt surface. The press assembly comprises either a single press roll, a lower and upper press roll. Moisture is removed at the pressure point of the press assembly and transferred into the felt.

The formed and pressed fabric is transferred to the surface of a rotating dryer cylinder, referred to as a Yankee dryer. The dryer assembly may also include a hot air cover surrounding the upper part of the Yankee cylinder. The cover has hot air nozzles which stick to the fabric and help in the removal of moisture. The cover includes an exhaust to remove the air from the cover chamber to control the temperature. The tissue is removed from the dryer surface using a doctor's knife to impart creping tissue. To help remove the fabric from the dryer surface in a uniformly controlled state, a creping adhesive is applied to a Yankee surface using a spray system. The spray system is a series of spray nozzles attached to a header pipe that extends across the width of the surface of the dryer. The creping adhesive can be any of the types commonly used in tissue paper manufacturing technology.

The creped paper tissue of the crepe cylinder is passed through a pressure point formed by a pair of rollers which is unwound on a large roll referred to as a parent roll. The tissue manufacturing process used in the examples can be essentially characterized as a dry crepe process of light weight. A 14-inch wide pilot plant scale machine was operated as follows.

Prior to the formation of tissue, the paper supply is contained in a machine chest in which additives of resistance to drying, dyes or other chemical additives are incorporated. The paper supply is delivered through a fan pump which flows from a head box through a slice at 0.1 percent to 0 percent consistency on the horizontal surface of a Fourdriener wire through which the water is removed and tissue formation takes place. The wire is carried around a suction chest roller, which helps in the removal of water and the formation of tissue. The wire is carried around several guide rollers and a wire turning roller and is fed back to the chest roller. One of those rollers is driven to drive the Fourdrinier wire The wet weave is formed on the upper surface of the Fourdrinier and transferred to a felt by means of a vacuum collection. The felt conveys to the sheet a set with pressure roller. The felt is moved around a roller with pressure, a rubber roller soli and is carried around the guide rollers and rotates back the collection with vacuum. The moisture is removed at the pressure point of the pressure roller and transferred to the felt.

The formed fabric is braided and transferred to the surface of the rotary dryer cylinder, commonly referred to as a Yankee dryer. The tissue is removed from the surface of the Yankee to a tissue dryness of between 95 percent and percent using a doctor blade. To aid in the removal of the fabric from the dryer surface in a uniform controlled manner, a creping adhesive is applied to the Yankee surface using a spray nozzle. The adhesive mixture used in these examples was a mixture of 70/30 of 7 percent polyvinyl alcohol and 30 percent of a starch base latex (Latex of National Starch 4441).

The creped paper web of the dried cylinder was passed through a pressure point formed by a pair of rollers and wound onto a parent roller of a desired size for testing. The paper machine formed a fabric 1 inch wide and ran at a reel speed of 40 to 5 feet per minute. All samples of creped and dry tissue samples were produced at a basis weight of 8 pounds per resm and a crepe of 18/20 percent. The samples were converted to tissue extracts (16 books per ream) for the entire test.

The present invention is shown in the following examples. All proportions used herein are p weight unless otherwise specified and the fib weight is based on the air dried weight of the fiber unless otherwise indicated.

Example 1 A light and dry weight crepe tissue product was made from a pulp obtained by pulping old newspaper. The control and sample tissues were prepared. The tissue product was made by reducing pulp with water for 20 minutes at a consistency of 6 porcient 150 ° F and at a pH of around 7. The pulp solution f maintained at 130 ° F and then divided in half.

The first part of the pulp solution refined a rate of one day of horsepower per ton using a refiner load, and then used directly as a supply for the dry creping tissue of liger weight using the papermaking equipment and the process described above to produce two stratus tissues at a basis weight of 1 lbs per ream (e.g., 8 lbs per ream stratum).

The remaining part of the pulp solution f adjusted to a solution consistency of 3 percent and rises to a target consistency of 5 percent. This washed step reduced the level of the fines and increased the freedom as measured by the Canadian Standard Freedom test.

The pulp was refined at a rate of one horse day strength per ton using a loading refiner, then fed into a paper making machine at a consistency to make paper of approximately 0, percent. The pulp was then used directly as a supply for the lightweight dry creped tissue using the process and the papermaking equipment described above to produce two-layer tissue at a basis weight of 16 pounds per ream (e.g. ream by stratum).

The control and sample of dry creped tissue was subjected to the hand-sensation test and the tension test. The hand feel tests were carried out essentially as described above except that a certified tester and commercially available reference samples were used instead of a test panel and the reference samples of specific pulps. Four test samples were produced and the numbers reported for the hand feeling results represent an average value for the four samples. The results were not analyzed using the weight proportion data analysis procedure described above. The test results are reported in table 1.

TABLE 1 As shown in Table 1, the wash increased CSF of the samples by more than 100 and reduced the fines to minus 35 percent in one sample and less than 30 percent in the other.

Example 2 The samples of Example 2 were made in substantial accordance with Example 1 except for the addition of a dry strength agent. Also, Samples A and B were made by recycling the wash stream back into the pulp. Therefore, most of the fines remained in the pulp; Samples C and D were made by washing the pulp and removing the fines.

The normalized tensile strength and hand feeling of these Samples are compared below in Table 2. Each data point in Table 2 represents the average of three samples.

TABLE 2 As shown in the data in Table 2, the removal of the fines resulted in a paper that has the same resistance around it, to the tension with a greater hand feeling (Sample C against Samples A and B) a paper which has a greater tensile strength with around the same meek feeling (Sample D against Samples A and B). Although the present invention has been described in relation to certain embodiments, it should be understood that the subject matter covered by the present invention is not limited to those specific embodiments. On the contrary, it is intended that the subject matter of the invention includes all the alternative and equivalent modifications as it may be included within the spirit and scope of the following claims.

Claims (18)

R E I V I N D I C A C I O N S

1. A method for making sanitary products of rough fibers comprising: pulping the rough fibers in water and agitation to produce a pulp solution, the pulp of the rough fibers has an average fiber content of about 40 percent; use an effective amount of pulp lava to reduce the fine content and increase the Canadian Standard Freedom; introducing the pulp to a papermaking consistency inside the headbox of a papermaking machine; Y Use the pulp in the paper manufacturing process to produce sanitary paper products.

2. The method as claimed in clause 1, characterized in that the fiber content is reduced to less than about 35 percent and the Free Canadian Standard is increased by more than about 50.

3. The method as claimed in clause 1, characterized in that the pulp is at a papermaking consistency ranging from about 1 percent to about 0.01 percent.

4. The method as claimed in clause 1, characterized in that the pulp comprises cellulose fibr at least 60 percent having a Kajaani aspere greater than 12 milligrams per 100 meters.

5. The method as claimed in clause 1, characterized in that the pulp of the rough fibers has an average fines content of more than about percent before treatment.

6. The method as claimed in clause 1, characterized in that the pulp of the rough fibers is washed so that the content of fines is reduced by about 30 percent.

7. The method as claimed in clause 1, characterized in that the pulp of the rough fibers is washed so that the Canadian Standard Freedom increased by more than about 70.

8. The method as claimed in clause 1, characterized in that the sanitary paper product is a tissue paper made at a basis weight of between 7 and 35 pounds per ream.

9. The method as claimed in clause 1, characterized in that the sanitary paper product is a paper napkin made at a basis weight of between 7 and 3 pounds per ream.

10. The method as claimed in clause 1, characterized in that the sanitary paper product is a paper towel made at a basis weight of between 12 and 4 pounds per ream.

11. A method for modifying the pulp of the recycled periodic paper, which comprises pulping the periodic paper in shaking water to produce a pulp solution, the pulp of the newspaper having a fine average content of more than about 40 percent; use an effective amount of pulp washing to reduce fines content and increase Canadian Standard Freedom; Y introducing the pulp to a consistency of paper fabric inside the headbox of a paper making machine where the pulp can be used in a process to make paper to produce sanitary paper products.

12. The method as claimed in clause 11, characterized in that the fines content and reduced to less than about 35 percent and the Canadian standard quantity is increased by more than about 50.

13. The method as claimed in clause 11, characterized in that the pulp is at a papermaking consistency ranging from about 1.0 percent to about 0.01 percent.

14. The method as claimed in clause 11, characterized in that the pulp comprises cellulosic fibers at least 60 percent of which are rough fibers having a Kajaani roughness of greater than 12 milligrams per 100 meters.

15. The method as claimed in clause 11, characterized in that the pulp of the newspaper has an average fines content of more than about 45 percent before the treatment.

16. The method as claimed in clause 11, characterized in that the pulp of the newspaper is washed so that the content of fines is reduced to less about 30 percent.

17. A method for modifying recycled newspaper pulp pulp, comprising: reducing periodic pulp paper in water with agitation to produce a pulp solution introduce the pulp to a papermaking consistency inside the headbox of a papermaking machine, the pulp has a fines content of less than about 35 percent and a Canadiens Standard Freedom of more than about 300 where the pulp can be used in a process to make paper to produce sanitary paper products.

18. A sanitary paper product comprising modified fibers of rough fibers where the product has a fine content reduced to less than about 4 percent and a Canadian Standard Freedom increased to more than about 250. SUMMARY A method for making sanitary fiber paper products. The method includes the steps of: (a) reducing the pulp of rough fibers in shaking water to produce a pulp solution, the pulp of the rough fibers has an average fines content of more than about 40 percent (b) use an effective amount of pulp wash to reduce fine content and increase Canadian Standard Freedom (c) introducing the pulp to a papermaking consistency of paper inside the headbox of the papermaking machine; and (d) use the pulp in the paper manufacturing process to produce sanitary paper products.