US3928496A - Synthetic fiber for paper and method for producing the same - Google Patents

Synthetic fiber for paper and method for producing the same Download PDF

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US3928496A
US3928496A US488486A US48848674A US3928496A US 3928496 A US3928496 A US 3928496A US 488486 A US488486 A US 488486A US 48848674 A US48848674 A US 48848674A US 3928496 A US3928496 A US 3928496A
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weight
paper
pulp
pva
copolymer
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Hiromu Takeda
Takuichi Kobayashi
Koichiro Oka
Kazumi Tanaka
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Toray Industries Inc
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Toray Industries Inc
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Priority claimed from JP8046973A external-priority patent/JPS5032326B2/ja
Priority claimed from JP8360973A external-priority patent/JPS5117608B2/ja
Priority claimed from JP8638473A external-priority patent/JPS5145691B2/ja
Application filed by Toray Industries Inc filed Critical Toray Industries Inc
Priority to US05/520,538 priority Critical patent/US3963821A/en
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    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
    • C08L25/02—Homopolymers or copolymers of hydrocarbons
    • C08L25/04—Homopolymers or copolymers of styrene
    • C08L25/08—Copolymers of styrene
    • C08L25/12—Copolymers of styrene with unsaturated nitriles
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/56—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polymers of cyclic compounds with one carbon-to-carbon double bond in the side chain
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
    • C08L51/003—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds

Definitions

  • a synthetic fiber substantially comprising: [30] Forelg" Apphcatlon Prlomy Data A. 5-40% by weight of a copolymer consisting of July 19, 1973 Japan 48-80469 a weight of alcohol and July 26, 1973 Japan 48-83609 b of acrylonitrile and Aug. 2, 1973 Japan 48-86384 of a copolymer consisting of c. 5595% by weight of styrene, and 1 gg 5 1 1 d. 545% by weight of acrylonitrile.
  • 51 Int. cm C08L 51/00; cost 33/20; This fi is F Pmducing Paper has a B32B 17/10. potentially fibrillar texture.
  • the present invention relates to a synthetic fiber for making paper, and to a method for producing the same.
  • many proposals have been made for the manufacture of synthetic paper consisting of synthetic fibers instead of paper made from natural pulp, by
  • Known methods using a polymer of the acrylic series include making the polymer a porous gel fiber and then beating the said fiber, treating the polymer with a liquid agent such as a strong mineral acid, a swelling agent, a deteriorating agent, and promoting fibrillation by polymer blending.
  • Methods have been suggested involving using a polymer of the olefin series, include splitting a film to bring about fibrillation.
  • the resulting pulp does not acquire hydrophilic properties, and therefore satisfactory dispersing properties in water at the time of wet paper making, and satisfactory adhesion of fibrils after the sheet is formed, have not been obtained.
  • Japanese Patent Application Publication No. 10655/1964 discloses there is insufficient fibrillating synthetic fibers in a swelling agent to obtain so-called hooked fibers having short, fine hooks.
  • the so-called hooks necessary for intertwining are short and are not self-adhesive, and therefore intertwining of fibers for the purpose, and the paper that is obtained is non-uniform.
  • fibrillation is carried out, as reported in said publication, using gel-like, non-collapsed fibers.
  • fibrillated fibers In order to convert fibrillated fibers into a sheet-like form, it is preferable that they should have hydrophilic properties, and self-adhesion, as well.
  • Japanese Patent 1 Application Publication No. 1 1851/1960 discloses a synthetic pulp fibril having feeler-like protrusions which are said to be capable of intertwining. As distinguished from the product ob- 2 tained by ordinary spinning processes, and because this fibril essentially lacks any so-called stalk fibers, it has the drawback, when synthetic paper is made therefrom, that the paper product has poor physical properties, especially tenacity. Accordingly, this fibril, together with other fibrous materials, is effectively utilized as an adhesive but it has the disadvantage that good paper cannot be obtained from this fibril alone.
  • fibers for paper and synthetic pulp consisting of (A) -90% by weight of a fiber-forming hydrophobic polymer and (B) 10-85% by weight of a copolymer in which a hydrophilic portion and a hydrophobic portion are bonded chemically, in which the hydrophilic portion is dispersed and oriented in the direction of the fiber axis.
  • An object of the present invention is to provide a fiber for a synthetic paper which is capable of yielding paper having high opacity, degree of whiteness and wet dimensional stability of a quality not attainable by paper made of conventional wood pulp.
  • Another object of the present invention is to provide a fiber capable of producing pulp and making synthetic paper by exactly the method normally used for wood pulp. This is done by imparting hydrophilic properties to the pulp a point which has been little considered in the case of conventional synthetic pulp, improving the dispersion properties in water when made into an aqueous slurry, and imparting adhesive strength between the fibrils.
  • Still another object of the present invention is to provide a method for making a synthetic fiber which is capable of producing a beaten fibril (pulp) having excellent intertwinement and adhesion among the fibrils, which can be made into paper in a wet system, using ordinary beating means of the type normally used with natural pulp, and capable of forming the resulting beaten fibril into paper consisting of of said beaten fibrils, or making paper consisting of beaten fibril and natural pulp in desired mix ratios.
  • a synthetic fiber which is capable of producing a beaten fibril (pulp) having excellent intertwinement and adhesion among the fibrils, which can be made into paper in a wet system, using ordinary beating means of the type normally used with natural pulp, and capable of forming the resulting beaten fibril into paper consisting of of said beaten fibrils, or making paper consisting of beaten fibril and natural pulp in desired mix ratios.
  • a synthetic fiber substantially comprising (A) about 540% by weight of a graft copolymer consisting of (a) about 20-80% by weight of polyvinyl alcohol, and (b) substantially the balance acrylonitrile, and (B) about 60-95% by weight of a copolymer consisting of (c) about 55-95% by weight of styrene and (d) substantially the balance acrylonitrile.
  • components (A) and (B) there may be provided, in addition to components (A) and (B), unreacted polyvinyl alcohol and acrylonitrile produced as by-products in the process of graft copolymeri'zation. Further, polymers of the polyvinyl alcohol series and the acrylic series may be added separately.
  • the fiber may comprise a mixed polymer system containing about 5-40% by weight ofa copolymer in which polyvinyl alcohol and acrylonitrile bond chemically, containing about -80% by weight of polyvinyl alcohol, and containing about 60-95% by weight of an acrylonitrile styrene copolymer containing about 5-45% by weight of acrylonitrile, in which system polyvinyl alcohol is present in an amount of about 2-55% by weight based on the weight of the entire mixed polymer system.
  • a method which is desirable for obtaining a fiber having the characteristics of the present invention involves dissolving such polymer composition in dimethyl sulfoxide or dimethyl acetamide and wet-spinning the resulting solution into an aqueous coagulating bath. Further drawing or heat-treating the spun fiber while it is a water-containing gel, as occasion demands, is desirable.
  • the fiber may contract by more than 45%.
  • the present invention has succeeded in producing a paper which has remarkably high opacity and wet dimensional stability by using a graft copolymer consisting of polyvinyl alcohol (hereinafter referred to as PVA) having hydrophilic properties and acrylonitrile (hereinafter referred to as AN) to impart hydrophilic characteristics to the pulp. At the same time, it disperses the copolymer into a copolymer consisting of styrene (hereinafter referred to as St) and AN.
  • PVA polyvinyl alcohol
  • AN acrylonitrile
  • the copolymer (A) should be a copolymer in which an AN component and a PVA component are chemically bonded to each other, so that the PVA component as a hydrophilic component and the AN component as a hydrophobic component exist in the form of, for example, a graft or block copolymer, and two different types of copolymer (A) and copolymer (B) coexist in a mixed system, in the aforementioned ratios.
  • copolymer (A) In the reaction for obtaining copolymer (A), a small amount of an AN polymer is produced which is not bonded to the hydrophilic component or the unreacted hydrophilic component, and is not bonded to AN.
  • the copolymers (A) and (B) exist within the aforesaid range, then without fail, the existence of such AN polymer or unreacted PVA does not become an obstacle in the practice of the present invention, insofar as its amount is within the aforesaid range. Therefore, the AN polymer need not be intentionally removed. What is important is that the AN component and the PVA component should chemically bond to each other within the aforesaid range and exist in chemically bonded combination.
  • the AN PVA copolymer used in the practice of the present invention is a graft copolymer, it is possible to produce the same by aqueous non-uniform polymerization or solution uniform polymerization.
  • the degree of polymerization of the PVA it is preferable that the average degree of polymerization be within the range of about 500-3400, preferably within the range of 600-1800.
  • PVA polymerization solvent
  • a polymerization solvent for example, dimethyl sulfoxide (hereinafter referred to as DMSO)
  • DMSO dimethyl sulfoxide
  • PAN vinyl monomer consisting mainly of AN
  • the PVA content in the graft copolymer be about 20-80% by weight, preferably about 35-65% by weight.
  • this content is less than about 20% by weight, the molecular weight of the graft polyacrylonitrile component is too high, seriously harming processability and impeding the development of hydrophilic properties.
  • the graft copolymer flows out in water and the objects of the present invention cannot be achieved.
  • a graft copolymer containing PVA having an average degree of polymerization of less than about 500 drops too much in water resistance and swelling strength, decreasing the water resistance of the paper obtained from the fiber, and not imparting preferred qualities to such paper.
  • a vinyl monomer other than AN but which is copolymerizable with AN, (for example, vinyl acetate, methyl acrylate, styrene and vinylchloride) may be copolymerized.
  • the St/AN copolymer, (component B) of the present invention may be prepared by ordinary methods of random copolymerization and known methods of block copolymerization such as aqueous non-uniform polymerization and bulk polymerization, for example.
  • the St/AN copolymer be compatible with the PVA/AN graft copolymer and the polymer of acrylic series.
  • the former is compatible with the latter two
  • the composition of the present invention consists of about 40% by weight of such a PVA/AN graft copolymer and about 60-95% by weight of such a St/AN copolymer.
  • the amount of said graft copolymer is less than about 5% by weight, the fiber produced by the method of the present invention is not fibrillated by beating, and has essentially no hydrophilic properties.
  • the amount of the graft copolymer exceeds about 40% by weight, the water resistance of the resulting paper grows worse. In addition, the opacity of the resulting paper is harmed.
  • the amount of the St/AN copolymer is less than about 60% by weight, the objective high opacity of the present invention cannot be achieved.
  • composition of the present invention is not limited to those consisting of said two copolymers only, but it may contain unreacted PVA and a polymer of the AN series produced as by-products in the process of graft copolymerization, and may include an intentionally added polymer of the acrylic series.
  • Homopolyvinyl alcohol has the property that a greater part thereof falls off when it is formed into an aqueous slurry in the process of making fibers and pulp, which is not essential for achieving the objects of the present invention.
  • this should not exceed about 23% by weight.
  • the opacity of the paper is harmed. Further, this is undesirable in view of resulting foaming and contamination of the aqueous slurry.
  • the amount of the polymer of the acrylic series should not exceed about 35% by weight. When higher, the desired high opacity cannot be achieved.
  • a separately polymerized linear polymer may be used.
  • One having a molecular weight of 20000 100000 is preferable.
  • a monomer of the vinyl series in an amount within the range not exceeding about 40 mol which may be used as a copolymerization component for graft copolymerization, may be used as well.
  • the high opacity is measured by a method to be mentioned later, and should be in excess of at least about 80%. When less, there is no measurable improvement over a value of about 70%. which is obtained by paper made from wood pulp.
  • PVA contained in an amount of about 255% by weight based on the total amount of the polymers is further preferable that in fibers constituted by these mixed polymers, PVA contained in an amount of about 255% by weight based on the total amount of the polymers.
  • the shape of the fibrils obtained by beating the fibers is very effective for promoting intertwinement of fibrils and adhesion of paper made from such fibrils. But when this amount is less than about 2% by weight of PVA, development of such properties is insufficient. If an amount-exceeding about 55% by weight of PVA is used, the water resistance, opacity and degree of whiteness of the resulting paper are reduced.
  • a wet spinning method using a solvent water coagulating bath is especially suitable for producing a synthetic fiber of the present invention.
  • solvents dimethyl sulfoxide (DMSO) and dimethyl acetamide (DMAc) are suitable.
  • DMSO dimethyl sulfoxide
  • DMAc dimethyl acetamide
  • the product is very suitable for beating and making paper.
  • the spun undrawn yarn is drawn to a predetermined draw ratio by ordinary methods in steam, hot
  • the composition of the present invention may be dissolved in DMSO or DMAc. Further, this solution may be wet spun by ordinary means into an aqueous spinning bath, for example, an aqueous solution of DMSO or DMAc containing up to the maximum of about by weight of DMSO or DMAc to produce an undrawn water-containing gel yarn. Further, such undrawn yarn may be drawn in a hot water bath, or in a steam atmosphere as occasion demands.
  • One specific method according to the practice of the present invention is dissolving such polymer composition in the aforesaid solvent at a concentration within the range of about 840% by weight based on the weight of said solvent.
  • the concentration is less than about 8% by weight, when the wet spun yarn is beaten, strong fibrils are unlikely to be present and the paper tends to be very brittle.
  • fibers of the present invention contain micro-voids, the average diameter of a greater part thereof not exceeding 5 microns, and that they be uniformly dispersed through- 7 out the entire structure of the fibers.
  • pa apparent specific gravity
  • S the average cross-sectional area of the substantial part of the fiber
  • d the average denier of the fiber
  • the structure of fibers of the present invention be such that:
  • undrawn water-containing gel yarns obtained by wet spinning into an aqueous spinning bath are subsequently heat-treated at a wet temperature of 80-180C, or preferably drawn at such wet temperature.
  • the temperature it is necessary for the temperature to be at least 80C.
  • the amount of a component which is amorphous and hydrophobic such as styrene
  • smooth drawing cannot be carried out at a temperature lower than 80C.
  • the temperature exceeds 180C, the St/AN copolymer melts and the monofilaments stick to each other. As a result, various obstacles are encountered when the fibrils separate and disperse by heating.
  • the draw ratio is selected in connection with the desired beating conditions.
  • the resulting fiber has a denier of about 0.1-30, and is cut into a length of about 1-50 mm, preferably 2.5-25 mm.
  • the copolymer (A) is dispersed as a plurality of particles in the copolymer (B) and arranged as independent phases in the direction of the fiber axis.
  • a fiber obtained by this production method is easily fibrillated by beating and may be made into pulp which has excellent dispersing properties in water. It is possible to make such fibers into an aqueous dispersion having a concentration of about 1-20% by weight and to beat the same by use of commercially available beating devices such as, for example, ball mills, beaters, PFI mills, and refiner. When, for example, a PFI mill is used, it is possible to use a linear pressure of 3.4 kg/cm a clearance of 0.1-0.3 mm and a cut fiber concentration of 3-12% by weight and by varying the total number of rotations of the rolls, it is possible to obtain a slurry having a freeness of about 40-750 cc.
  • Fibers obtained according to the present invention are easily fibrillated, forming a pulp having excellent dispersing properties in water.
  • known wet paper making methods are applicable. As a result, it is possible to make paper having high levels of opacity, a high degree of whiteness and an excellent wet dimensional stability not attainable by conventional paper made from wood pulp.
  • a high draw ratio fiber of the present invention be subjected to wet heat-treatment in boiling water, or in a steam atmosphere. It is preferable that the heat-treating temperature be about -180C, preferably about l20C. The time is preferably within the range of about 30 seconds to about 8 minutes, and it is to be expected that the final fiber will contract by at least about 45% of the initial length.
  • the wet heat-treatment can be carried out, before the fiber is cut, as a continuous yarn, and after the fiber contracts, it may be cut into a length of about 1-15 mm, preferably about 7-15 mm, and then cut fiber may be beaten.
  • a low draw ratio yarn of the present invention (such as a draw ratio between 1.0 and 2.5, for example) may be beaten without being subjected to such wet heattreatment to produce a pulp having excellent dispersing properties.
  • a fiber of the present invention need not have a uniform denier throughout the direction of the fiber length.
  • the solution of said composition may be jetted at a high speed into the coagulating bath and may be discharged into a coagulating bath flowing at high speed.
  • composition of a PVA/AN graft copolymer of the present invention may be determined in a given case by the following means. From the polymer solution after graft copolymerization, it is possible to extract the polymer as a solid component by known methods, such as re-precipitation operations and filtering operations. After the solid component is dried, it is subjected to hot water extraction for 48 hours using a 9 Soxhlet extractor. One component extracted by such operations is the unreacted PVA polymer. Subsequently, after the solid component is dried again, it is extracted with dimethyl formamide (hereinafter referred to as DMF) at 100C for hours, and the extracted component is a polymer of the AN series.
  • DMF dimethyl formamide
  • the remaining component is a PVA/AN graft copolymer. From the amount charged, the amount of the re-precipitated polymer, the amount of product extracted with hot water, and the amount of product extracted with DMF, the compositions of the graft PVA and graft PAN in the graft copolymer are determined.
  • the amount of the AN component is determined, and from the remaining amount, the amount of the ST component is determined.
  • the degree of opacity and the degree of whiteness of paper referred to are measured as follows. Using an integral sphere-type HTR meter, manufactured by Japan Precision Optical Co., Ltd. and using a green filter, when the reflexibility obtained when a standard white plate is placed at the back of a sheet of paper having a basis weight of 40 g/m is made 100, the degree of opacity is expressed by a reflexibility when a black plate is placed at the back of said paper; and using blue filter, in case a reflexibility of a standard MgO plate is made 100, the reflexibility when at least 6 sheets of the sample paper are accumulated is read and made a degree of whiteness.
  • a beaten fibril (synthetic pulp) obtained by beating the resulting fiber may be formed into paper consisting of substantially 100% of said beaten fibril and into paper consisting of a mixture of said beaten fibril and wood pulp at an optional mixing ratio.
  • the resulting paper is characterized in that the degree of whiteness, degree of opacity, wet dimensional stability, permeation resistance, surface picking strength and printability are simultaneously attainable at balanced high levels which have not been realizable by conventional natural pulp.
  • the paper can develop excellent aptitute in many uses for paper such as paper for reprography like coated paper, photographic paper, India bible paper, thin paper, tracing paper, electrostatic recording paper, electrophotographic paper, magnetic recording paper and copying paper; and paper used in combination with these papers for reprography or independently like pressure sensitive copying paper, cards for statistical machine, punch tapes, business forms, optical mark recognition paper and optical character recognition paper as well as magnetic ink character recognition paper, release paper, paper board and wrapping a er.
  • paper for reprography like coated paper, photographic paper, India bible paper, thin paper, tracing paper, electrostatic recording paper, electrophotographic paper, magnetic recording paper and copying paper and paper used in combination with these papers for reprography or independently like pressure sensitive copying paper, cards for statistical machine, punch tapes, business forms, optical mark recognition paper and optical character recognition paper as well as magnetic ink character recognition paper, release paper, paper board and wrapping a er.
  • FlGfl is a graph showing the relationship between pulp freeness and degree of beating, using a yarn prepared in accordance with Example 1 herein, and
  • FIG. 2 is a graph showing a similar relationship for the pulp obtained in the procedure of Example 2 hereof.
  • EXAMPLE 1 1 kg of PVA having a degree of polymerization of 1400 (NM 14, manufactured by Nihon Gosei' Kagaku Co. Ltd.) was dissolved in 19 liters of DMSO at a tem-' perature of 50-60C for about 2 hours with stirring to obtain a uniform solution.
  • DMSO dodecyl mercaptan
  • APS ammonium persulfate
  • DM dodecyl mercaptan
  • the PVA used herein was not particularly limited, however, when a judgment was made from the viewpoint of the mechanical properties of the obtained fiber, the adhesion and dispersing properties in water of the fibril after being beaten, a degree of polymerization within the range of 500-3400 was found to be preferable.
  • the degree of polymerization of this copolymer expressed as intrinsic viscosity (1;) measured in 1 1 methylethyl ketone (hereinafter referred to as MEK) at 30C was 0.5.
  • the resulting beads-like AS copolymer was dried by a flush dryer to remove the moisture completely.
  • this copolymer was dissolved in DMSO at 70C with stirring to obtain a uniform polymer solution having a concentration of 27%.
  • This mixed polymer solution was stirred by a spiraltype stirring blade for 3 hours to obtain a mechanically uniform mixed solution, which was spun as a spinning solution through spinning nozzles each having a diameter of 0.1 mm into a DMSO/water (70/30) coagulating bath, and the resulting undrawn yarn was continuously drawn. After drawing, the drawn yarn was washed with water sufficiently to remove the solvent.
  • the denier of 12 Beaten fibrils whose freeness values were 200 cc, 320 cc, and 390 cc were made into aqueous solutions having concentrations of 0.02%, and were introduced into a manual paper-making sheet machine (using 80 mesh 5 metal screen) manufactured by Kumagaya Riki Co.,
  • wet papers were three different manually made papers (wet papers).
  • the basis weightsvof these wet papers were 40.1 g/m
  • the wet papers were dried by an FC dryer manufactured by FC Seisakusho Co., Ltd.,
  • wet strength and excellent degree of air permeation which we have been unable to attain with conventional wood pulp, are developed despite the absence of any addition of any filler or additive in the case of the three papers prepared according to the present invention.
  • Paper made from wood pulp NBKP/LBKP /60 blend. freeness 320 cc. basis weight 40 g/m.
  • Sample A Paper made from beaten pulp having a freeness of 200 cc.
  • Sample B Paper made from beaten pulp having a freeness of 320 cc.
  • Sample C Paper made from beaten pulp having a freeness of 390 cc.
  • Dry shrinkage Shrinkage in a diagonal line when wet paper was dried at 105 C for 2 minutes by an FC drum dryer.
  • the PVA portion of this yarn was dyed with OsO, (osmic acid) and when an ultra thin (cross-sectional) cut piece was taken and observed under an electron microscope, it was observed that a plurality of voids having an average diameter of less than 5 microns were uniformly dispersed in the cross-section and the copolymer (A) was dispersed in the copolymer (B) as the dispersed phase.
  • OsO osmic acid
  • FIG. 1 of the drawings shows the effect of such beating on pulp freeness, by showing the relation between the number of revolution of the PFI mill and the freeness. It is clearly observed from FIG. 1 that a fiber based on the present invention forms paper-forming fibrils by beating.
  • the degree of opacity was expressed as reflexiibility when a black plate was placed at the back of sample paper.
  • the standard was the reflexibility obtained by placing a standard white plate at the back of the sample paper, using a green filter, and was designated as 100.
  • the degree of whiteness was expressed as reflexibility when at least 6 samples were accumulated, when as a standard the reflexibility of a standard MgO plate using a blue filter was designated as 100.
  • EXAMPLE 2 I. 61 g of PVA having a degree of polymerization of 1800 dissolved in 550 g of DMSO at 50C for 2 hours necessary, the degree of acidity of the system was controlled. Next, to the solution, 0.5 g of APS was added dropwise and polymerization was carried out at 50C for 6 hours. Thereafter, 0.57 g of hydroxylamine sulfate was added as a polymerization stopper together with a small amount of DMSO to the system to complete the polymerization. The polymer solution so obtained, having a graft copolymer, had 100 grams of the entire polymer, grams of the graft copolymer of 80 g, a
  • This spinning solution was spun from spinning nozzles each having a diameter of 0.15 mm into a DMSO/- water (40/60) coagulating bath at 30C, and the undrawn yarn was drawn to 4.5 times in hot water and washed with water to remove the remaining solvent.
  • the denier of the resulting yarn was 4. This yarn had values of:
  • This yarn was cut into fiber lengths of 3 mm, and the cut pieces were beaten in a PFI mill manufactured by Kumagaya Riki Co., Ltd., Japan (clearance 0.2 mm, weight 3.4 kg, pulp concentration 5%) to carry out fibrillation.
  • FIG. 2 shows various stages of thorough-- ness of beating as variation of degree of freeness (C.S.F.) as well as the total number of revolutions of the PFI mill. From FIG. 2, it is apparent that beating of the fiber proceeds and fibrils are formed by the beating treatment.
  • This fiber was made into three different beaten fibrils having freeness values of 400 cc, 300 cc and 200 cc by the PFI mill. Each of these beaten fibrils was further beaten by a home mixer (SM-225, pulp concentration 2%, manufactured by Sanyo Denki Co., Ltd., Japan) 14 into pulp having a freeness of 305 cc (pulp A), 215 cc (pulp B), and 95 cc (pulp C).
  • SM-225 pulp concentration 2%, manufactured by Sanyo Denki Co., Ltd., Japan
  • pulps A, B and C were caused to have pulp concentrations of 0.2% and were made manually into papers using a manual paper-making sheet machine (using mesh metal screen) manufactured by Kumagaya Riki Co., Ltd., Japan.
  • the basis weights of these papers were 50 g/m and 35 glm
  • the wet papers were dried in an FC dryer (at 105C for 2 minutes).
  • Table 2 the measured results of various characteristics of these papers are shown. As conspicuous, remarkable characteristics, a remarkably high degree of whiteness, a degree of opacityand a wet strength which we had been unable to realize with conventional wood pulp were obtained.
  • the shrinkage at the time of drying the wet papers was low to about the same degree as paper made from wood pulp, and their air permeating degree was high.
  • Table 3 shows the results, from which it is understood that papers obtained from mixtures obtained by mixing lower amounts of pulps obtained by beating a fiber shown in the present invention (beaten fibrils) with said base pulp of wood pulp exhibit a high degree of whiteness, degree of opacity, wet strength, breaking length and surface strength which have heretofore been unattainable with paper made from 100% wood pulp. It was able to develop well balanced paper characteristics, exceeding the properties of natural pulp.
  • PVA NM-l4, manufactured by Nihon Gosei Kagaku Co., Ltd.
  • PAN molecular weight 63000
  • the denier of the resulting yarns was 3.5. These yams were cut into lengths of 3 mm, and the cut pieces were beaten by a PFI mill the same as in Example 2. The degrees of beating are shown in Table 4. In the cases of ent wet papers by a manual paper making instrument manufactured by Kumagaya Riki Co., Ltd., Japan, dried at 105C for 2 minutes by an FC dryer and the characteristics of the dry papers were measured. The results are shown in Table 5. The fibers consisting of simple mixtures of the respective components cannot obtain required paper strength and bulk density as paper and did not become paper that was capable of withstanding actual use. In contrast, the fibers consisting of the graft copolymers and the AS copolymers developed excellent paper-forming performances as will readily be understood from Table 5.
  • the solution was precipitated using methanol as a precipitating agent to obtain a solid PVA AN graft copolymer, which was treated by vacuum drying for 24 hours to remove the methanol and a very small amount of the solvent.
  • this copolymer was dissolved in DMAc at 60C to prepare a uniform solution having a concentration of 15%.
  • an AS copolymer [1 0.51, AN/St 23/77) was dissolved in DMAc at 80C to prepare a uniform solution having a concentration of 15%.
  • the aforesaid two kinds of solutions were mixed to prepare spinning solutions containing 10, 25, 40, 60% of PVA.
  • Each of these spinning solutions was spun from a spinning nozzle each having a diameter of 0.11 mm into a solvent-water (DMAc/- water 60/40) coagulating bath, and continuously washed with steam.
  • the denier of the resulting yarn was 4.
  • This yarn was cut into fiber lengths of 3 mm, the cut pieces were beaten in a PFI mill and further beaten by a home mixer to obtain a beaten fibril having a freeness (C.S.F.) of 250 cc, which was made into an aqueous dispersed liquid having a concentration of 0.02%, from which manually made wet paper having a basis weight of 50 g/m was made, which was dried at 102C for 15 minutes by a drum dryer to obtain paper.
  • the results of measuring the characteristics of these four kinds of paper are shown in Table 6.
  • Pulp slurries having papermaking concentrations of 0.02% by weight were used, 12 liters of the liquids were 20 The draw ratio was 4.5, the denier was 3 and the boiling water treatment time was 1.5 minutes, the beating conditions were made the same as in Example 1 and the papermaking conditions were the same as in Examformed into papers by a 80 mesh metal screen for mak- 5 ple 6.
  • Table 9 mg paper to make papers having basis weights of 40 From Table 9, it is clear that only the compositions g/m according to the present invention gave good results.
  • The' wood ul used was NBKP/LBKP 50 p p EXAMPLE 8 (weight ratio) having a freeness of 413 cc.
  • the papermaking characteristics and paper properties are shown in Table 8.
  • AN was solution polymerized in DMSO using N,N' azobisisobutyronitrile as a catalyst to prepare a DMSO Table 8
  • EXAMPLE 7 By the same method as in Example 5, various compositions of PVA/AN graft copolymers and AN/St copolymers were prepared as shown in Table 9. These copolymers were prepared by the same method as in Example 1, formed into spinning solutions and wet spun.
  • compositions having various compositions were prepared from the resulting polymer solution and a PVA- /AN graft copolymer prepared by the same method as in Example 5 to carry out the similar determinations to those of Example 7.
  • the results are shown in Table 10. In Table 10, it is shown that only the compositions according to the present invention gave good results.
  • the resulting yarn was subjected to beating in a PP! mill using the method shown in Example 6. The total number of the roll revolution was varied and various beaten pulps were prepared. As a reference, yarn not treated with steam was similarly processed.
  • Fibers according to the method of the present invention obtained in examples up to Example 8 were beaten, and the resulting beaten fibrils (synthetic pulps) were mixed with wood pulp. From the resulting mixtures paper products were made. The wet strength and dimensional stability of these papers were measured and the results are shown in Table 12. The wet dimensional stability was shown by change of dimension when the relative humidity (RH) was varied from 65% to at 20C using a TAPPI paper elasticity tester.
  • RH relative humidity
  • Table 13 shows the results obtained by making papers from beaten pulps obtained by cutting the wet 50C, the solution was stirred for 8.5 hours, and then drawn yarns into a length of6 mm adding 400 g of such 6.4 g of hydroxylamine sulfate and 7 g of H 50, were cut pieces in a state of aqueous slurry having a concenadded thereto to stop the reaction.
  • this polymer solution in methanol consisted of 11.9%
  • the papers were made using a square-type sheet by weight of unreacted PVA, 8.7% by weight of polymachine manufactured by Kumagaya Riki Co., Ltd., acrylonitrile and 79.4% by weight of a PVA/AN graft Japan, while observing the standard operations decopolymer containing 50.1% by weight of PVA. This scribed in JIS P-8209.
  • the basis weights of the papers polymer solution was designated (A).
  • Example 11 Example 11 to obtain samples made from synsolutions having different polymer concentrations.
  • This yarn was cut into a length of 4 mm, beaten and formed into paper by the same means and method as in Example l 1 to obtain paper having a basis weight of 50 g/m, a length at break of 3.9 km, a degree of whiteness of 94% and a degree of opacity of 97%.
  • EXAMPLE 14 The wet strength and wet dimensional stability of the papers made from the beaten fibers according to the method of the present invention obtained in examples 5 up to Example 13 were measured and the results are shown in Table 15.
  • the wet dimensional stability is shown as the change of dimension when the relative humidity (RH) was varied from to 95% at 20C using a TAPPI paper elasticity tester.
  • the wet strength is shown as the ratio of the tensile strength of a sample immersed in water at 20C for 20 minutes and is obtained by comparison of a tensile test carried out immediately thereafter to the tensile 65 strength of the same sample when it was dry.
  • the same measured results on paper made from 100% wood pulp are shown in Table I5.
  • the synthetic fibers according to this invention consist essentially of,
  • a synthetic fiber capable of being fibrillated for forming paper consisting essentially of:
  • a synthetic fiber according to claim l wherein the 2 55% b w i ht based on the entire weight of the average degree of polymerization of said polyvinyl fib alcohol is about 600-3400.
  • a synthetic fiber according to claim 1 further 4'
  • a Synthetic fiber accordmg to clam] 1 further containing, in a range from trace amounts to about containing, in a range from trace amounts to about 5 23% by weight homopolyvmyl alcohol. 35% by weight, a polymer of the acrylic series.
  • a synthetic fiber according to claim 4 wherein A Synthetic fiber aCFOYdiPg l claim 6, f said polyvinyl alcohol and homopolyvinyl l oh l i said polymer of the acrylic series IS polyacrylomtrrle. said graft copolymer are present in an amount of about

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4015043A (en) * 1974-09-09 1977-03-29 Kanzaki Paper Manufacturing Co., Ltd. Electrostatic recording material
US4108818A (en) * 1975-03-03 1978-08-22 Japan Exlan Company Limited Process for the melt-shaping of acrylonitrile polymers
US6171443B1 (en) * 1990-03-05 2001-01-09 Polyweave International, Llc Recyclable polymeric synthetic paper and method for its manufacture
US20060152341A1 (en) * 2004-12-17 2006-07-13 Mcdonough William A Communication apparatus and method of distribution of same

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US5861213A (en) * 1995-10-18 1999-01-19 Kuraray Co., Ltd. Fibrillatable fiber of a sea-islands structure

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3826712A (en) * 1972-01-18 1974-07-30 Asahi Chemical Ind Acrylic synthetic paper and method for producing the same acrylic fibers wet spun from a blend of hydrolyzed and unhydrolyzed acrylic polymers having at least 60 % acrylonitriles by weight and paper made from such fibers

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3826712A (en) * 1972-01-18 1974-07-30 Asahi Chemical Ind Acrylic synthetic paper and method for producing the same acrylic fibers wet spun from a blend of hydrolyzed and unhydrolyzed acrylic polymers having at least 60 % acrylonitriles by weight and paper made from such fibers

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4015043A (en) * 1974-09-09 1977-03-29 Kanzaki Paper Manufacturing Co., Ltd. Electrostatic recording material
US4108818A (en) * 1975-03-03 1978-08-22 Japan Exlan Company Limited Process for the melt-shaping of acrylonitrile polymers
US6171443B1 (en) * 1990-03-05 2001-01-09 Polyweave International, Llc Recyclable polymeric synthetic paper and method for its manufacture
US20060152341A1 (en) * 2004-12-17 2006-07-13 Mcdonough William A Communication apparatus and method of distribution of same
US20090212552A1 (en) * 2004-12-17 2009-08-27 Mcdonough William A Communication apparatus and method of distribution of same

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DE2434927A1 (de) 1975-03-13
NL7409713A (nl) 1975-01-21
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IT1020663B (it) 1977-12-30

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