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
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/02—Synthetic cellulose fibres
  • D21H13/08—Synthetic cellulose fibres from regenerated cellulose
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/42—Formation of filaments, threads, or the like by cutting films into narrow ribbons or filaments or by fibrillation of films or filaments
  • D01D5/423—Formation of filaments, threads, or the like by cutting films into narrow ribbons or filaments or by fibrillation of films or filaments by fibrillation of films or filaments
• • 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
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
  • D21H11/18—Highly hydrated, swollen or fibrillatable fibres
• • 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
  • D21H5/1236—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of fibres which have been treated to render them suitable for sheet formation, e.g. fibrillatable fibres
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
  • Y10S264/47—Processes of splitting film, webs or sheets

Definitions

• tYPe 1180 are 13 m (CL 1 2 ..14 extremely difiicult to d1sperse In Water in the absence of dispersing agents.
• the inability to produce fibI'llS This invention relates to a new and novel synthetic 10 from conventional synthetic cellulosic fibers such as viscellulose fiber, method of making such fiber and prodcose rayons has restricted their use in forming water-laid ucts containing the fiber. webs to certain types of specialty papers.
• Fibrous articles such as certain types of non-Woven
• the principal purpose of the present invention is to fabrics and water-laid sheets, depend to a large extent provide a fibrillated synthetic cellulose fi ber. on an interlocking of the fibers and of fibrillae on the Another purpose of this invention is to provide a fibers for their physical properties such as strength, tear method for fibrillating synthetic cellnlosic fibers. and burst.
• a further purpose of the invention is to provide waterclassed as a non-woven fabric is paper commonly formed laid fibrous sheets of the novel fibrillated synthetic cellufrom a furnish which contains the dispersed fibers.
• Another object of this invention is to provide strong, become fibrillated. Fibrillation as employed in the tough water-laid fibrous sheets composed of the novel paper-making art is obtained substantially by the beating fibrill-ated synthetic cellulose fibers with or without other or vigorous agitation of fibers in the presence of extremely synthetic fibers or natural fibers or mixtures thereof. large excess quantities of Water.
• the synthetic cellulosic fibers that is, fibers and subsequently separating the fibrilla-ted fibers fromformed by regenerating the cellulose from a collulosic the aqueous liquid.
• compound for example, such as those produced by the A flow diagram of the process is as follows:
• Synthetic Cellulose Fibers i Controlled partial hydrolysis i Fibrillatable F"- Synthetic Cellulose Dry Fibers Fibers Dried Flbr-illatable Synthetic Cellulose Mechanical agitation or brushing in aqueous Brush in aqueous liquid Fibrillated Syncheci Cellulose Fibers Dried Fibrlli lated Synthetic Cellulose- Mix with water (with or without; other Mix with water (with or without other fibers) Sheet and dry Water-laid Product;
• Fibers v l Mix in water (winner without other sheet and dry fibers) if I waber-laid Product? urrnsh sheet and nit-
• various investigators in studying the structure of both native and regenerated cellulose have subjected cellulose fibers to a severe hydrolyzing treatment wherein the amorphous cellulosic material is removed and only a very fragile cellulosic skeleton remains. This residue or remaining portion of the fiber consists essentially of cellulose crystallites.
• a measured quantity of the fibers is transferred to a suitable acid solution and is maintained in the acid for varying periods of time.
• the material is thoroughly washed to remove the acid and may be subjected to subsequent tests.
• the acid solution is a 2.5 N hydrochloric acid solution maintained at about 105 C. which is the boiling point.
• the fibers are maintained in the boiling acid solution for about 15 minutes. This treatment removes the so-called amorphous cellulose and the residue consists of the cellulose crystallites recovered from the fibers.
• my copending application Serial No. 636,483, filed January 28, 1957, now Patent No. 2,978,446 there is disclosed a method of preparing stable dispersions of level-off D.P. cellulose by subjecting cellulose crystallites in this form to a vigorous mechanical agitation in water.
• the level-off DR of the cellulose from the regenerated cellulose fibers lies in the range of from about 20 to about 50.
• native cellulosic fibers are subjected to a like treatment, it is found that the level-off DR of native cellulose is in the range of from about 150 to about 300.
• regenerated cellulose fibers may be partially hydrolyzed to render them satisfactory for use in conventional paper-making processes by subjecting the fibers to a closely regulated and controlled hydrolysis treatment without measurably decreasing the weight of the fibers so as to reduce the average basic DR of the cellulose in the partially hydrolyzed fiber to from about 20% to about 75% of the average basic DR of the cellulose in the parent fiber.
• any form of regenerated cellulose fiber may be subjected to the controlled hydrolysis to render the fibers suitable for the purpose of this invention
• the specific conditions for satisfactory hydrolysis are dependent upon the specific cellulose fine structure of any particular fiber and are chosen to elfect a limited cutting of the cellulose chains which run continuously through the amorphous areas of the respective fine structure. In general, there is no measurable weight loss and, in any event, the weight loss should not exceed about 1%.
• the average basic DR of regenerated cellulose is in the range of about 350 to about 550.
• the hydrolysis treatment must be sufiicient to lower the average basic DR of the cellulose in the fiber to a value within the range of about 20% to about 75 of the origin-a1 D.P.
• the hydrolysis treatment is prolonged or sufficiently severe to reduce the average basic DR of the cellulose below about 20% of its value in the parent fiber, then the fiberis weakened excessively and the partially hydrolyzed fiber will disintegrate into a powder upon me chanical' agitation, thereby preventing the manufacture of water-laid sheets. If, on the other hand, the hydrolysis is not sufiicient to reduce the average basic D.P. below about 75 of its value in the parent fiber, then upon subsequent mechanical treatment, the partially hydrolyzed fiber will not fibrillate to an extent which permits the manufacture of a satisfactory water-laid sheet.
• the hydrolysis treatment may be satisfactorily carried out by subjecting the fibers to the action of a dilute acid solution maintained at a temperature up to about 95 C. under atmospheric pressure or higher temperatures may be employed when the treatment is carried out in a closed vessel under pressure.
• Convenient and economiically feasible treating solutions may be aqueous solutions of sulfuric acid having a concentration up to about 10% acid by weight and hydrochloric acid solutions containing up to about 8.5% hydrochloric acid.
• the time required will be dependent upon the acid c ncentration and the temperature maintained during the hydrolysis treatment. Because it is possible to utilize higher temperatures when the treating liquid is under pressure, the concentration of acid may be lowered sub stantially.
• the hydrolyzing conditions for any specific fiber will be satisfactory for fibers having diameters up to about 40 or more microns. It has been found, however, that there is a gradual decrease in the length of the fibrils which are formed on treated fibers as the diameter of the fiber increases.
• the fibers may be cut to the desired length prior to subjecting them to the controlled hydrolysis or the fibers subjected to this treatment may be of considerable length as compared to natural fibers and cut to length after the treatment as in a paper mill beater.
• Samples of commercial viscose rayon staple fiber having a relatively thin skin with respect to core may be satisfactorily treated under mild or severe hydrolyzing conditions. Because of the ease with which this type of fiber is hydrolyzed, the milder conditions are preferred.
• the length of the fiber may be from about 2 millimeters to as high as of an inch or greater and the diameter of the fibers may vary up to about 40 microns or more.
• Sulfuric acid solutions containing up to about 10% acid are satisfactory and the temperature of the acid solution may vary up to about 95 C. It is quite apparent that the time required will vary inversely with the concentration of the acid and inversely with the temperature.
• the fibrillating characteristics of regenerated cellulose fibers treated with dilute acid solutions were determined by subjecting the treated fibers to a brushing action for 20 minutes in the Waring Blendor at a 1.5% consistency.
• the dry regenerated cellulose fibers had a diameter of about 12 microns and were about /2 inch inlength.
• samples of a commercial textile grade of viscose rayon having a thin skin and a crenulated cross-section were subjected to the action of dilute sulfuric acid under various conditions. After each specific treatment, a portion of the sample of the treated fibers was used to determine the average basic DR of the cellulose and another portion subjected to the fibril lation test.
• the data in Table I illustrates the fibrillating characteristics as related to the average basic D.P. of the treated fibers.
• the average basic D.P. has been reduced below the limit hereinbefore set forth, the treated fiber when beaten in water breaks up into fine particles because it has been weakened to too great an extent.
• the physical characteristics of the fiber before treatment such as the tenacity or tensile strength and percent elongation, have been decreased to some extent by the controlled hydrolysis and the treated fibers have excellent fibrillating characteristics.
• hydrolysis treatments are not the exclusive means for rendering regenerated cellulose fibers fibrillatable as defined herein but are merely illustrative. Other means are entirely satisfactory.
• a polyvalent metal ion may be included as a catalyst and may allow the use of lower acid concentrations and shorter treating periods.
• a three minute treatment of the fibers in a 2% sulfuric acid solution containing 1% ferric chloride at 80 C. is equivalent to a 10 minute treatment in a 10% sulfuric acid solution at 80 C.
• the controlled hydrolysis treatment which is suflicient to render the normally non-fibrillatable fibers readily fibrillatable under normal paper-making conditions does not drastically reduce the physical characteristics of the fiber. This is demonstrated by a comparison of the 75 single fiber characteristics of the control samples of the 7 two types of rayon staple fibers mentioned hereinbefore and of samples of both of these types of fibers which have been subjected to both the low temperature and the high temperature controlled hydrolysis.
• the hydrolysis treatment as set forth in Table V has been selected as a more or less optimum hydrolysis treatment for the two specific types of fibers.
• the treated fibers formed as described herein may also be mixed with natural paper-making fibers or other synthetic fibers in a conventional paper mill beater and may be handled and processed in accord with conventional paper-making methods.
• the products exhibit an unusually uniform texture whether the fiber consists entirely of the partially hydrolyzed fiber formed as described herein or when blended or mixed with nat- Ural paper-making fibers or other synthetic fibers.
• One particularly advantageous application of'the treated fibers includes the mixing of fibers prepared according to the present invention with fibers which normally produce a rather weak wet strength paper such as newsprint web.
• the treated regenerated cellulose fibers may be of a longer length and of various thicknesses to contribute an appreciably higher Wet strength as well as a higher dry strength.
• the manufacture of the fibers may involve only the controlled hydrolysis treatment and subsequent washing and drying of the fibers or may include a washing of the treated fibers followed by a fibrillation treatment and a final drying step.
• the fibers have been dried after the controlled hydrolysis treatment, they are subsequently handled by the same method which is used in producing water-laid webs from a refined paper pulp; that is, the fibers are subjected to a brushing action for a period of from '15 minutes to 3 hours.
• the fibers after controlled hydrolysis are washed and fibrillated as by the action of a paper mill beater and then dried, no additional brushing is required.
• the typical fibrillae of the dry, fibrillated fiber are developed by a mere mixing in water.
• the dry, fibrillated. fiber it is merely necessary to disperse the fibers in water by any of the conventional mixing devices, such as by brushing in a paper mill heater or by mixing with a Cowles stirrer and then form the furnish which is passed directly to the head box of the paper machine.
• the fibers are then sheeted to form a web in exactly the same manner that normal paper-making fibers are converted into a web.
• the thickness of the sheeted fibers is regulated to form any desired grade or thickness of fibrous web.
• the web may be subjected to calendering rolls, etc., and dried in accordance with conventional paper-making processes.
• the fibers treated in accordance with the present invention are to be mixed or blended with other fibers, it is preferable to separately disperse the respective fibers in Water and subject the fibers to the required action separately to develop the fibrillate before mixing the dispersions.
• the separate and independent beatings may be regulated to obtain maximum fibrillation of the respective types of fibers.
• Satisfactory water-laid webs of the fibers of this invention may be formed by any of several conventional methods.
• manufacture of paper may be illustrated by standard paper laboratory procedures which involve the use of a TAPPI standard beater and the preparation of handsheets with a Noble and Wood screen.
• grams of fiber were dispersed in the TAPPI standard beater at a consistency of 0.6%.
• the lever weight refers to the weight applied to the lever which moves the bedplate to contact the beater roll.
• the standard weight in beating wood pulps is 5500 grams.
• the Weight in pounds of the samples refers to the calculated Weight for a ream of 500 sheets 25 inches by 40 inches.
• Woodpulp A-Commercial western hemlock bleached sulfite pulp Woodpulp A-Commercial western hemlock bleached sulfite pulp.
• Woodpulp B-Mixed hardwood bleached neutral sulfite semi-chemical pulp Woodpulp B-Mixed hardwood bleached neutral sulfite semi-chemical pulp.
• the burst factor or the tear factor or the tensile strength of the papers may be selectively altered.
• the tear factor may be increased by about 35% with no appreciable alteration of the burst factor and tensile strength.
• the tear factor may be doubled without an appreciable change in the burst factor and with less than a 10% change in the tensile strength by the use of 20% of the treated rayon.
• a 20 minute beating or mixing in a Waring Blender is approximately equivalent to a 2 hour brushing in the standard TAPPI Valley Beater.
• commercial thin skin rayon fibers and thick skin rayon fibers as described above were subjected to such brushing after partial hydrolysis.
• the partial hydrolysis consisted of treating the fibers for 10 minutes in a 10% sulfuric acid solution at 80 C.
• the thick skin rayon fibers were treated for 20 minutes in a 10% sulfuric acid solution at 80 C. Both types of fibers were A inch in length.
• the thin skin fibers were of a 1.5 denier size (about 12.5 micron diameter) and the thick skin fibers Were of a 0.5 denier size (about 6-7 micron diameter).
• the fiber or mixture of rayon fibers and wood pulp was beaten or brushed in a standard Waring Blender for 20 minutes at a 1.2% consistency and handsheets were prepared from the slurry by the standard paper technique using a Noble and Wood screen.
• the fiber was pounded in a mortar before being subjected to the brushing.
• the data is illustrative of variations obtainable by the use of the fibers of this invention.
• Pulp O- The data illustrate-s that the treatment and size of the fibers may be selected to impart desired characteristics to the water-laid web.
• the fibers Were subjected to a pounding in a mortar which is somewhat comparable to a grinding or crushing, a higher tear factor and tensile strength is noted. Finer fiber size or small diameter fibers form paper having higher strength, burst and tear properties.
• the blending or mixing of fibers of the present invention and natural paper-making fibers results in small changes in the bursting strength but appreciable increases in the tear factor as compared to papers formed entirely 3; the fibers of this invention and of natural paper-making ers.
• All of the foregoing data on the properties of waterlaid Webs refers entirely to the properties of Webs formed from a dispersion of the fibers in Water without the presence of other substances normally used in the manufacture of water-laid Webs.
• Sizing materials, fillers, binders, substances adapted to improve the wet strength and any other desired substances as normally used in the paper and pulp industry and in the manufacture of non- Woven fabrics may be incorporated in the fiber slurry or may be incorporated in the water-laid web.
• no calendering of the web is employed in the standard paper laboratory methods of forming handsheets.
• the strength characteristics of Webs formed with fibers of this invention are improved by a calendering in the same manner as Webs formed of natural paper-making fibers.
• synthetic resins such as polyoleiins, acrylics, urea-formaldehyde resins, inelamine-formaldchyde resins, etc. may be applied at any suitable stage in the manufacture of the web or sheet.
• melamine-formaldehyde resins may be utiiized to improve the wet strength of the sheet.
• the sheet may be impregnated with a fireproofing agent before final drying.
• the collecting surface may be of any desired shape and form and the thickness of the web may be such as to form a non-woven textile of the nature of felt.
• the web sheet may be transferred to any desired mold and finished by pressing and drying in such mold.
• the foregoing examples have included mixtures of fibers of the present invention and natural paper-making fibers or wood pulp fibers.
• One of the highly desirable characteristics of the fibers of the present invention is that the fibers may be of substantially identical diameter and length whereas the naturally occurring fiber-s in fact are in the nature of bundles of individual fibers and are not all of the same length.
• accurate desired modifications of water-laid webs may be effected by the use of fibers of definite and uniform dimensions.
• the examples illustrate merely mixtures of two different types of rayon which have been partially hydrolyzed as described herein and mixtures of these fibers with wood pulp fibers, any other desired type of papermaking fiber or any other type of fiber may be mixed with the fibers of the present invention.
• Fibers which are commercially available for a wide variety of textile uses, as pointed out above, are not adapted in themselves for the manufacture of paper.
• the fibers of this invention may also be mixed with other synthetic and natural fibers such as cotton, glass fibers, wool fibers, polyester fibers, cellulose acetate fibers, nylon fibers and other vegetable fibers.
• the fibers of thepresent invention may be of any desired length and will satisfactorily bond together other fibers which do not fibrillate.
• fibrillatable regenerated cellulose fibers which are satisfactory for the manufacture of water-laid webs in accordance with the present invention are defined herein as partially hydrolyzed regenerated cellulose fibers wherein the average basic DR of the cellulose lies within the'range of from about 20% to about 75% of the average basic DR of the parent fiber.
• These fibers are further characterized by their fibrillating property which results in the formation of water-laid webs having certain minimum strength characteristics. The fibrillating property is measured by subjecting the fibers to a brushing treatment, forming a water-laid web in accordance with standard paper laboratory techniques and measuring the strength and tear factor of the water-laid sheet.
• rayon fibers which have not been partially hydrolyzed when subjected to the same test conditions form sheets which do not have a measurable tensile strength and a measurable tear factor.
• the magnitude of the minimum strength characteristics for paper sheet formed from the fibers of this invention may be visualized by comparison With the similar characteristics of ordinary newsprint.
• Normal newsprint papers have a tensile strength of about 3000 meters and a tear factor of about 47 in the machine direction of the web and a tensile strength of about 1400 meters and a tear factor of about 53 in a direction transverse to the machine direction.
• the average basic DR of the cellulose as referred to herein and in the claims is based upon methods as described in the literature.
• the method employed is that published by Orlando A. Battista, Molecular Weight of Cellulose, Ind. Eng. Chem., Anal. Ed, 16, 35l-354 (1944).
• the method employed is that published by Orlando A. Battista et al., Level-Off Degree of Polymerization, Ind. Eng. Chem., 48, 333-335 (1956).
• a water-laid web comprising felted, water fibrillated, partially hydrolyzed regenerated cellulose fibers, the cellulose of the partially hydrolyzed fibers having an average basic D.P. within the range of from about 20% to about 75% of the original average basic D.P. of the cellulose of parent regenerated cellulose fibers subjected to a hydrolysis treatment and the partially hydrolyzed fibers being characterized by having substantially the same weight as the parent fibers and by forming a standard hand sheet having a tensile strength of at least 400 meters and a tear factor of at least about 50 from a slurry formed by beating the partially hydrolyzed fibers in water for 20 minutes in a standard Waring Blendor at a 1.2% consistency.
• a water-laid web comprising a felted mixture of water-fibrillated, partially hydrolyzed regenerated cellulose fibers and other fibers, the cellulose of the partially hydrolyzed regenerated cellulose fibers having an average basic D.P. within the range of from about 20% to about 75 of the original average basic D.P.
• the partially hydrolyzed fibers being characterized by having substantially the same weight as the parent fibers and by forming a standard hand sheet having a tensile strength of at least 400 meters and a tear factor of at least about 50 from a slurry formed by 13 beating the partially hydrolyzed fibers for minutes in a standard Waring Blendor at a 1.2% consistency.
• paper comprising felted, water-fibrillated, partially hydrolyzed regenerated cellulose fibers the cellulose of the partially hydrolyzed fibers being characterized by having an average basic D.P. within the range of from about 20% to about 75% of the original average basic D.P.
• the partially hydrolyzed fibers being characterized by having substantially the same Weight as the parent fibers and by forming a standard hand sheet having a tensile strength of at least 400 meters and a tear factor of at least about 50 from a slurry formed by beating the partially hydrolyzed fibers in water for 20 minutes in a standard Waring Blendor at a 1.2% consistency.
• paper wherein all of the fibers are water-fibrillated, partially hydrolyzed regenerated cellulose fibers, the cellulose of the partially hydrolyzed fibers being characterized by having an average basic D.P. within the range of from about 20% to about 75% of the original average basis D.P.
• the partially hydrolyzed fibers being characterized by having substantially the same weight as the parent fibers and by forming a standard hand sheet having a tensile strength of at least 400 meters and a tear factor of at least about 50 from a slurry formed by heating the partially hydrolyzed fibers in water for 20 minutes in a standard Waring Blendor at a 1.2% consistency.
• the method of forming water-laid fibrous webs which comprises subjecting regenerated cellulose fibers to a hydrolysis treatment until the average basic D.P. of the cellulose has been reduced to between about 20% and about 75% of the original average basic D.P. of the cellulose of the parent regenerated cellulose fibers without substantially reducing the weight of the regenerated cellulose fibers, brushing the treated regenerated cellulose fibers in water, sheeting the brushed fibers to form a waterlaid web and drying the water-laid web.
• the method of forming water-laid fibrous webs which comprises subjecting regenerated cellulose fibers to a hydrolysis treatment until the average basic D.P. of the cellulose has been reduced to between about 20% and about 75 of the original average basic D.P. of the cellulose of the parent regenerated cellulose fibers without substantially reducing the weight of the regenerated cellulose fibers, forming a mixture of the partially hydrolyzed regenerated cellulose fibers, other fibers and water, brushing the mixture of the partially hydrolyzed regenerated cellulose fibers and of other fibers in Water, sheeting the mixture of fibers to form a water-laid Web and drying the Water-laid web.
• the method of forming water-laid fibrous Webs which comprises subjecting regenerated cellulose fibers to a hydrolysis treatment until the average basic D.P. of the cellulose has been reduced to between about 20% and about of the original average basic D.P. of the cellulose of the parent regenerated cellulose fibers without substantially reducing the weightof the regenerated cellulose fibers, brushing the treated regenerated cellulose fibers in Water to form a slurry, brushing natural papermaking fibers in water to form a second slurry, mixing the slurries, sheeting the mixture of brushed fibers to form a water-laid web and drying the water-laid web.
• a method of forming water-fibrillatable regenerated cellulose fibers the step which comprises subjecting regenerated cellulose fibers to a hydrolysis treatment until the average basic D.P. of the cellulose has been reduced to between about 20% and about 75% of the original average basic D.P. of the cellulose of the parent regenerated cellulose fibers without substantially reducing the weight of the regenerated cellulose fibers.
• a method of forming regenerated cellulose fibers which fibrillate when mixed in water the steps which comprise subjecting regenerated cellulose fibers to a hydrolysis treatment until the average basic D.P. of the cellulose has been reduced to between about 20% and 75 of the original average basic D.P. of the cellulose of the parent regenerated cellulose fibers without substantially reducing the weight of the regenerated cellulose fibers, brushing the treated regenerated cellulose fibers in water, separating the brushed, treated regenerated cellulose from the water and drying the regenerated cellulose fibers.
• steps in the method of forming water fibrillatable regenerated cellulose fibers as defined in claim 15 wherein the hydrolysis treatment comprise subjecting the regenerated cellulose fibers to dilute sulfuric acid.
• Water fibrillated, partially hydrolyzed regenerated cellulose fibers having an average basic D.P. within the range of from about 20% to about 75% of the average basic D.P. of the cellulose of parent regenerated cellulose fibers subjected to a hydrolysis treatment and the partially hydrolyzed fibers being characterized by having substantially the same weight as the parent fibers, by fibrillating when mixed with water and by forming a standard hand sheet having a tensile strength of at least 400 meters and a tear factor of at least about 50 from a slurry formed by brushing the partially hydrolyzed fibers in water for 2 hours in a standard Valley beater at a 1.2% consistency.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Paper (AREA)
• Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)

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• 0
  • NL NL246561D patent/NL246561A/xx unknown
• 1958
  • 1958-12-31 US US784033A patent/US3052593A/en not_active Expired - Lifetime
• 1959
  • 1959-12-08 GB GB41723/59A patent/GB934786A/en not_active Expired
  • 1959-12-19 DE DE19591446606 patent/DE1446606A1/de active Pending
  • 1959-12-29 BE BE586111A patent/BE586111A/fr unknown
  • 1959-12-30 FR FR814557A patent/FR1245863A/fr not_active Expired

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