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CA1091412A - Flowing fluid into nozzle in flash-spinning emulsion and forming pulp - Google Patents

Flowing fluid into nozzle in flash-spinning emulsion and forming pulp

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Publication number
CA1091412A
CA1091412A CA222,963A CA222963A CA1091412A CA 1091412 A CA1091412 A CA 1091412A CA 222963 A CA222963 A CA 222963A CA 1091412 A CA1091412 A CA 1091412A
Authority
CA
Canada
Prior art keywords
pulp
polymer
fiber
synthetic pulp
paper
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA222,963A
Other languages
French (fr)
Other versions
CA222963S (en
Inventor
Tadami Kamaishi
Takao Kitagawa
Takashi Fujita
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toray Industries Inc
Original Assignee
Toray Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP3147874A external-priority patent/JPS50123917A/ja
Priority claimed from JP50007062A external-priority patent/JPS5824524B2/en
Application filed by Toray Industries Inc filed Critical Toray Industries Inc
Application granted granted Critical
Publication of CA1091412A publication Critical patent/CA1091412A/en
Expired legal-status Critical Current

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Classifications

    • DTEXTILES; PAPER
    • D21PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21HPULP 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
    • D21H5/00Special paper or cardboard not otherwise provided for
    • D21H5/12Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
    • D21H5/20Special 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
    • DTEXTILES; PAPER
    • D01NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01DMECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00Formation of filaments, threads, or the like
    • D01D5/11Flash-spinning

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Textile Engineering (AREA)
  • Paper (AREA)

Abstract

Abstract of the Disclosure The synthetic pulp-like material of the present invention is a fibrillated fibrous material composed mainly of hydrophobic polymer and a hydrophilic polymer, in which the hydrophilic polymer exists in the shape of irregular islands when viewed in cross section taken at a right angle to the fiber axis. The hydrophilic polymer is arranged as continuous or intermittent striae in the direction of the fiber axis, in a substantially greater part of said fibrous material, the ratio of the transverse dimension (?1) to the longitudinal dimension (?2), (?1/?2) is within the range of about 1-10 and the longitudinal dimension (?2) does not exceed 10 microns.
This synthetic pulp-like material, useful for making synthetic paper, is produced by emulsion flash-spinning, in which a separate fluid is introduced into a nozzle upon discharging an emulsion containing polymers.

Description

10g1412 Background of the Invention The present invention relates to a synthetic pulp-like material.
More particularly, the present invention relates to a ~ine, fibrillated fibrous synthetic pulp and to a process for producing such synthetic pulp-like material by emulsion flash-spinning.
Description of the Prior Art Heretofore, various kinds of synthetic pulp-like materials have required, apart from the characteristic performances derived from synthetic I polymers, that the requisite properties of conventional wet paper-making ¦ 10 processes and the properties heretofore possessed by natural paper be satisfied per se. Strictly speaking, these prior pulp-like materials required that all the favorable properties of natural pulp be possessed along with the characteristics of synthetic pulp.
Prior processes for producing synthetic pulp include M ash-spinning processes involving flushing a polymer solution; split fiber processes involving cutting and beating drawn fibers, solution shearing processes utilizing shearing forces while throwing a polymer solution into a non-solvent for the polymer; processes including the steps of drawing melt-spun, ; dry-spun or wet-spun fibers and thereafter cutting the drawn fibers; and emulsion flash-spinning processes involving flushing emulsions of polymer solutions. Fibrous materials produced by the foregoing processes further undergo a beating process and are formed into paper-like materials.

~*.

The favourable characteristics of natural pulp, especially wood pulp which can be made into wet paper are first, its dispersibility in water and secondly, its self-adherence between fibers. In any one of the aforementioned processes for producing synthetic pulps, difficulties are encountered in making synthetic pulp having such characteristics.
We have proposed a process for preparing synthetic pulp utilizing an emulsion flash-spinning process.
The emulsion flash-spinning process comprises emulsifying polymer solutions and a non-solvent for the polymer3 preferably an aqueous solution, in the presence of a surface active agent and flash-spinning the resulting emulsion at a high temperature under high pressure, producing a fibrous material which is fine and easy to beat. Moreover, water-soluble polymers may be uniformly distributed everywhere in the interior and on the surface of the fiber, and therefore, the fibrous material having excellent dispersibility in water and self-adherence was produced. Of the aforesaid various processes for preparing synthetic pulps, the emulsion flash-spinning process is an excellent process for preparing the same. However, the emulsion flash-spinning process alone is not sufficient to achieve those properties expected of synthetic pulp.
Pulp made by emulsion flash-spinning has the following advantages:
1. freeness at the time of paper-making is poor,
2. effectiveness in increasing the opacity of paper is small,
3. processability ~for example, size press and pigment coating) of paper (mixed paper and 100% paper) is poor, and 1~91412
4. printability (printing aptitude) of paper is also poor.
These points show that conventional pulp made by emulsion flash-spinning processes satisfies to some extent the conditions of dispersibility in water and self-adherence. However, this pulp does not show the same characteristics as those of wood pulp and does not sufficiently satisfy the expectations of synthetic material (for example, opacity which is mainly determined by the shape of the pulp freely designed).
These problems are considered to be closely related to the ~ine (superfine) structure of the pulp. Namely, the basic structure of conventional pulp obtained by conventional emulsion flash-spinning processes is generally a fine filmy structure and because there is good distribution of hydrophilic polymer on the surface and in the interior of the pulp, the dispersibility of the pulp in water and its self-adherence are favorable. However, because such conventional pulp has side-effects such as a tendency to block the mesh of a metal screen for paper-making or cover gaps among pulps, the freeness of the pulp is further hindered and the printability and processability of paper made from such pulp are poor. Also, pulp having a filmy structure obtained by emulsion flash-spinning is high in self-adherence but when the pulps come into close contact with each other, light rays tend to permeate the pulp, thereby lowering the opacity.

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On the other hand, when the size of a pulp having a filmy structure is coarse or when the pulp has a so-called "twist of paper"
shape in which the pulp rolls itself, such pulp is not poor in freeness and sometimes its opacity becomes high, but there is a serious reduction of strength, for example, surface strength. Further, the breaking length becomes low Ob~ects of the Invention An obJect of the present invention is to provide a synthetic pulp-like material which is improved in freeness and opacity over the conventional synthetic pulp obtained by emulsion flash-spinning processes.
Another ob~ect of the present invention is to provide a superfine fibrillated papermaking fibrous material which has excellent dispersibility in water, excellent affinity with synthetic pulps or with natural pulp, and having high opacity.
Still another ob~ect of the present invention is to provide a process for preparing such synthetic pulp-like material.
Further ob~ects of the present invention will become apparent from the following general description.
General Description of the Invention In accordance with the invention, there is provided in a process for preparing a synthetic pulp-like material, the steps which comprise emulsion flashing an emulsion substantially containing (a) a fiber-forming hydrophobic polymer and a hydrophilic polymer which is substantially incapable of dissolving with a solvent for said hydrophobic polymer, (b) the solvent for said hydrophobic polymer which has a boiling point lower than the melting point of said hydrophobic polymer, and (c) an aqueous dispersion medium into a low pressure zone through a nozzle, and flowing a fluid into the nozzle portion in an area of reduced pressure.

~091412 In accordance with the present invention, there is provided a synthetic pulp-like material comprising a fibrillated fibrous material com-prising a hydrophobic polymer and a hydrophilic polymer which are substantially incapable of dissolving simultaneously in a solvent for said hydrophobic polymer, said hydrophilic polymer viewed on a cross-section taken at a right angle to the fiber axis of said fibrillated fibrous material assuming a structure of substantially non-circular irregular islands having a thickness which is less than about 1 micron, wherein, (a) when viewed in longitudinal cross section parallel to the fiber axis of said fibrillated fibrous material, the same hydrophilic polymer is arranged in the direction of the fiber axis in the form of continuous or intermittent striae, and (b) substantially a ma~ority of said fibrillated fibrous material has a dimenqion equal to or less than about 15 mm and the shortest dimension is greater than the thick-ness of the fiber, and wherein (c) when viewed in cross-section taken at a right angle to the direction of the fiber axis of said fibrillated fibrous material, the ratio of the transverse dimension (Ql) to the longitudinal dimension (Q2), (Ql/Q2)~ is within the range of about 1-10 and the longitu-dinal dimension is equal to or less than about 10 microns.
Such a synthetic pulp-like material of the present invention is obtained by preparing a superfine fibrillated fiber by emulsion flash-spinning comprising heating a polymer composition composed mainly of a fiber-forming polymer (I) together with a solvent (II) having a boiling point lower than the melting point of the fiber-forming polymer (I) and being uniformly soluble at a temperature higher than said boiling point and an aqueous dispersion medium (III) at a temperature higher than the normal boiling points of the solvent (II) and the aqueous dispersion medium (III), and spinning the resulting emulsion through a nozzle while flowing a fluid into an internal nozzle portion where pressure is suddenly reduced.

n 1~1412 In pulp of the present invention, a hydrophilic polymer is distributed everywhere on the fine surface and in the interior of the pulp.
Portions of the pulp in the form of fibers are remarkably few and in a representative example of such pulp, they are aggregations of wire-like fibers differing in size. As a result, such pulp is excellent both in dispersibility in water and in freeness. Moreover, it is found that when such pulp is made into paper, the resulting paper has excellent brightness, opacity and surface strength and is excellent in processability and printability.
Characteristic of the pulp of the present invention is its unique fiber shape as compared with conventional pulp. Especially excellent is the relation between the opacity and the surface strength of paper obtained from such pulp. In general, the opacity of paper is inversely proportional to the surface strength of the paper so that a paper having a tendency to a higher opacity, has a lower surface strength. In the paper made with the pulp of I the present invention, the surface strength is unlikely to be reduced, despite ¦ 'the high opacity.
When the pulp is to be obtained by processes other than the emulsion flash-spinning process, it is difficult to provide hydrophilic polymers uniform-ly on the surface and in the interior of the pulp. The hydrophilic polymers are important for the dispersibility in water and self adherence of the pulp which are the most important requirements for synthetic pulp. For example, in case of a flash-spinning process or a solution shearing process, the representative processes for preparing synthetic pulp, since these processes utilize the treatment of a uniform solution of a polymer, use of a hydrophilic polymer which is not simultaneously dissolved in a solvent is difficult. By a split fiber process and a melt spinning process the premise of which is the melting of a polymer, uniform mixing of base polymers and a hydrophilic polymer is difficult. After fibrous materials obtained by these processes are made into pulp-like materials by a method such as beating, the pulp is either coarse or hydrophobic, and it is very difficult to obtain paper by ordinary wet paper-making processes having the desired characteristics.
Drawings Figure 1 is a cross-section of one embodiment of nozzle useful for producing products and for practicing the method of this invention, into which nozzle a fluid flows at a point during the process of the present A. invention.
Figure 2 is a photograph (900 magnifications) showing one embodiment of the synthetic pulp-like material of the present invention.
Figure 3 is a cross-section of a fiber taken at a right angle to the fiber axis.
Figure ~ is a cross-section of a fiber embodying features of this invention, taken centrally in the direction of the fiber axis and at a scale as indicated thereon.
Figure 5 is a schematic view taken through a fiber according to this invention, showing the relationship between Ql and Q2 as referred to herein.

1()9141Z

Detailed Description of the Invention Synthetic pulp-like material of the present invention, has a novel and highly advantageous structure. In the process of making paper from a fiber or synthetic pulp, almost all of such fiber or synthetic pulp is beaten. During the beating process such fiber or synthetic pulp can possibly be broken or fractured and/or changed in shape. Therefore in respect to the structure of synthetic pulp of the present invention the object would be to provide particles which are not unduly small by providing a ratio of pulp passing through an 80 mesh metal screen, measured in accord-ance with JIS-P-8207, below 50%. However, the fine structure of pulp as defined in the test of this specification hardly changes at all in response to changes of degree of beating.
The internal shape of a pulp-like fibrous material has the following structure with respect to a hydrophilic polymer; a hydrophilic polymer viewed as a cross-section taken at a right angle to the fiber axis of the pulp has the structure of a plurality of islands of irregular shapes which are not mainly circular shapes and which islands have a thickness less than about 1 micron, preferably less than about 0.5 micron. When viewed in longitudinal cross-section, taken parallel to the fiber axis, the same hydrophilic polymer is arranged in the form of continuous or intermittent striae.
These remarkable internal shapes should be observed under special conditions with reference to the cross-sectional area of the dried fiber and pulp. It is not possible to observe the hydrophilic polymer visually as distinct.

~Q91412 from the base polymer, said hydrophilic polymer becoming distinguishable only by observing an ultra-thin section of such hydrophilic polymer after it is stained with an atom of heavy metal under an electron microscope. Sometimes the hydrophilic polymer partially assumes a sea structure, namely, the irregular shapes gather and are partially arranged without all the hydrophilic polymers being distributed at random. The hydrophilic polymer forms a complex with a surface active agent coexisting therewith, and although the hydrophilic polymer assumes mainly the structure of islands, it sometimes exists as plates or layers. Therefore in defining the dimension of such hydrophilic polymer islands distributed in the pulp fiber it is preferred that the thickness be used. The thickness of the hydrophilic polymer islands distributed in the pulp fiber is less than 1 micron, generally about 1 - 0.001 micron (lOA), and preferably 0.5 - 0.005 micron, and in a representative case, most hydrophilic polymer islands distributed in the pulp fiber have a thickness of 0.1 - 0.01 micron. The thickness of the hydrophilic polymer islands of the pulp fiber is below 1/2, preferably 1/5 that of the pulp fiber. If the thickness of the pulp fiber is outside such range, various properties such as mechanical strength and optical properties of the pulp are inferior resulting in a paper of lower brea~ing strength lower opacity and lower smoothness. The width of the hydrophilic polymer islands distributed in the pulp fiber is less than the width of the pulp fiber; Ql (Ql >Q2);
Q2 is a thickness of the pulp fiber measured in a direction taken at a right angle to Ql In a pulp-like fiber, voids are sometimes present, but this depends upon the process used in producing the pulp-like fiber. In certain processes, voids seldom occur. Voids are closed gaps distributed in the shape of islands on a cross-section at a right angle to the fiber axis.
However, on a cross-section taken parallel to the fiber axis, almost all _ 10 -. .~ ,~, .,~, the voids remain open. It is preferable that the voids do not produce independent systems closed in all directions. When the voids do produce such independent systems, the pulp is caused to float in water. It is the size of such voids which shows a thickness below 1/2 the thickness of the pulp fiber. The shape of such voids is close to circular, with the flat shape being seldom seen.
The outer shape of a pulp-like fibrous material is such that at least about 70%, preferably at least about 90% and more preferably at least about 99%, of the entire pulp assumes the below-defined pulp shape. Such pulp has a pulp fiber length of less than 15 mm, the shortest length thereof being larger than the fiber width (Ql) On a cross-section taken at a right angle to the direction of the fiber axis, the ratio of a transvere dimension tor width,Ql) to the longitudinal dimension (or thickness Q2)' Ql/Q2 is within the range of about 1 - lO, preferably l<Ql/Q2<5, more preferably l<Ql/Q2<3 and the pulp thickness ~2 is below about lO microns, preferably below about 5 microns. The preferable range of the pulp fiber width Ql is below about 10 microns, more preferably below about 5 microns.
The preferable range of the pulp fiber length is from below 6 mm to more than the fiber width.
The shapes of the fiber and the pulp may be observed under various types of microscopes. Under an optical microscope, the outer shape and section are seen. With respect to electron microscopes, the scanning-type and the transmission-type are used. Under the scanning-type of electron microscope the structure is observed by irradiating a dried and Au-.~

1~91~12 sputtered sample and catching a secondary electron image.
Also, the outer shape of the sample is seen in three dimensions and it is possible to observe the shapes of the cross sections, both longitudinal and transverse, of the sample. Under the transmission-type of electron microscope, structures are observed by catching an electron image transmitting the sample. The hydrophilic polymer portion in the fiber and pulp is observable with this type of electron microscope after preparing an ultra-thin section which is stained with an atom of heavy metal. The ultra-thin section is prepared generally by embedding a fiber or pulp and thereafter cutting the fixed fiber or pulp by a ultra-microtome to below 500 ~.
The shape of the section of the sample may be more precisely determined by embedding the sample and thereafter cutting the same into sections and observing a cut section by application of a scanning-type electron microscope.
The width (Ql) and thickness (Q2) of the fiber are determined as follows: In a cross section taken at a right angle to the direction of the fiber axis in a stable conformation of a pulp fiber, a plurality of different rectangles having each side circumscribed with the fiber surface, is taken. The long side and the short side of the rectangle, possessing the minimum area of all of said rectangles, are then labelled Ql and Q2' respectively. ~his section of the fiber is inscribed with the rectangle having the minimum area. In case there are two or more rectangles having the minimum area, the rectangle which has the minimum Ql is adopted. Accordingly, Ql~Q2 This is shown in Figure 5.

- 12 _ 1~9141Z

The stable conformation of the pulp fiber referred to above is directed to a shape of pu~p fiber which is in stable condition in water; however, when the pulp is of a simple structure, it has a shape like that of the pulp in a paper-like material obtained under normal conditions of paper-making and drying. In the case of a filmy shaped structure, however, or portion thereof, it does not always follow that the shape in water is the same shape in dried state. In view of the interpulp or intra-pulp (self-) adherence being enlarged by the hydrophilic polymer or the surface active agent, and the shape changes at the time of drying. The conformation in water of pulp may be observed by a stereo-type microscope. Dried pulp may be observed under various microscopes including scanning-type electron microscopes of various magnifications; however, for consideration and interpretation of conformation the aforesaid problem of adherence must be taken into account.
Even if the cross-sectional configuration of the pulp is within the aforesaid range of ~l/Q2' sometimes there is pulp having an uneven surface. The scope of the present invention includes the shape of a cross-sectional configuration of the pulp within the Ql/Q2 range taken at a right angle to the direction of the fiber axis with a tangent being drawn in contact with two convex portions corresponding to the most concave portion of the pulp surface, and the shortest distance from the tangent to the most concave portion (Ql') is below the width (Ql) of the cross-section of the fiber. However, pulp which has a thin filmy shape, or which originally had a ~13 thin filmy shape, but which self-contracted (sometimes such pulp rolls in like a twisted piece of paper) due to the hydrophobic property as seen in the case of conventional synthetic pulp, are not desirable in the present invention.
~ he portion ~rom the tip Or the convex portion corresponding to two portions concave to the base, namely a protruded portion, and the partition of closed gaps distributed in the shape of islands, should not be filmy.
The length of the protruded portion and the length of the partition are preferably below 10 times the thickness thereof.
The specific surface area of a fiber or pulp of the present invention is more than about 1 m /g, preferably more than about 3 m /g. The specific surface area may be measured by the so-called BET process. This specific surface area may be inferred to some extent from microscopic observation; however, care should be taken in this, because the estimated value tends to be less than the actual value when there are voids.
In measuring the specific surface area of a fiber or pulp, it is necessary to be attentive to the method used in preparing a sample for measuring. A sample wetted by water is mechanically drained and thereafter dried slowly.
~ormally, a sample dried in air at room te~perature is used, however, freeze-dry methods and critical point drying methods may be used. In case the pulp or fiber has strong self-a&esion due to the self-a&erence of the fibers, the specific surface area tends to decrease. Hence, sudden drying should be avoided.

10~141Z

Pulp of the present invention has the following superior properties. Because of the special shape of the pulp and distribution of hydrophilic polymer, the dispersibility in water of the pulp and the freeness at the time of paper-making are excellent. The tension of wet paper made from such pulp (paper made from a mixture of such synthetic pulp and natural pulp or 100% synthetic paper) is great and the drying speed rapid. Drainage time becomes a standard of freeness at the time of paper-making, measuring thereof is carried out in accordance with TAPPI standard method T221, namely:
to a square-type sheet machine (25 cm X 25 cm), 12 liters of water and 3 g of the pulp are added. The resultant mixture is stirred thoroughly and thereafter, the stirred mixture is passed through a metal screen of about 150 mesh and 12 liters of water are removed. The drainage time of 100%
synthetic pulp is below 50 seconds, preferably below 35 seconds. The drain-age time of mixed pulp with another pulp such as wood pulp is in accordance with the respective composition and the additional properties of these conditi.ons are roughly established.
When paper is made from pulp of the present invention, such paper shows a relationship between excellent opacity and brightness stemming from the peculiar outer shape and inner shape of such pulp. In general, paper made from wood pulp is low in brightness and opacity. l'hese draw-backs are overcome by adding a filler at the time of paper-making, but a problem is brought about in terms of strength. The pulp of the present invention is very effective in improving these problematical conditions.
In addition, the pulp of the B

present invention brings about an improved effect in the relationship between the unique opacity as compared with conventional synthetic pulp and the surface strength. Such effect was investigated by using a 4:1 mix (wood pulp/synthetic pulp of the present invention) paper.
Wood pulp is used having a CSF (Canadian Standard Freeness) of 400 cc (~20 cc), an opacity of 61% (~1%) and a surface strength (D-wax number) of llA (+lA) when 50 g/m of 100% of this wood pulp is made into paper. Paper-making is in accordance with JIS-P 8209. Namely, natural pulp the concentration of which is controlled to a proper value and a slurry, of for example, synthetic pulp of the present invention, are added into a square-type sheet machine (manufactured by Kumagaya Riki Co., Ltd., Japan) enabling 25 cm x 25 cm paper to be obtained with 12 liters of water are added thereto and the wet paper obtained is drained, couch pressed using ~ sheets of filter paper, and further, inserted between 6 sheets of filter paper and plane-pressed.
The resulting wet paper is then dried at 110C using an FC
dryer (manufactured by FC Seisakusho, Japan).
When 20% of the pulp of the present invention is mixed with the aforesaid wood pulp, the relation between the opacity (y, %) and the surface strength (x, A) of paper made from the resulting mixed pulp having a basis weight of 50 g/m is as follows.
y > -1.5 x + 85 .
The range at which more preferable properties are shown is y > -1.5 x 1 88 .

Paper made ~rom wood pulp and 20% conventional pulp having a filmy structure shows the relation y 1.5 x ~ 85 in accordance with the aforesaid measuring conditions. The opacity varies depending upon the opacity of the wood pulp to be mixed, the mixing ratio of the synthetic pulp and basis weight of paper. However, said opacity may be expressed by the following general formula y = 100 [1 - ke ~P a)w]
wherein y is the opacity, p is the mixing ratio of synthetic pulp (lOp%) w is the basis weight (g/m ), is a constant corresponding to the capacity of the wood pulp, ~ is a constant corresponding to the difference in opacity between the synthetic pulp and the wood pulp and k is a constant corresponding to the conditions for making paper.
Under normal paper-making conditions and drying conditions by a photograph dryer, in one example k = 0.68, ~ = 0.011 and~= 0.088. At this time,the opacity of 100% wood pulp paper having a basis weight of 50 g/m is 60.8% and the opacity of paper made from mixed pulp containing 20% of the pulp of the present invention is 83.7%.
Pulp of the present invention exhibits excellent surface strength because a hydrophilic polymer i5 distributed everywhere in the interior and on the surface of the pulp and self-a&erence between the pulps is good.
Further, because the shape of the pulp fiber tends toward uniformity, fine and close to a rod-shape as compared with conventional filmy pulp and coarse pulp, the pulp remarkably reflects rays diffusedly raising the opacity of the paper remarkably. Because the conventional pulp of a filmy structure transmits ~ -17-rays to a greater extent, the opacity of such conventional pulp is not very high. The shape which has become rod-like by self-contraction of the original filmy shape is good with respect to freeness, however, ~n a graph of opacity versus surface strength, the curve for such properties for papers of conventional processes is below that of the present invention indicating that convention~l processes result in poorer surface strength or lower opacity paper from the present invention. The pulp of the present invention is good in permeability and in soaking in a liquid such as water.
Accordingly, processing of the surface of the paper such as, for example, size press and coating of various kinds of pigments is easy and the effect thereof is remarkable. Also, such paper shows an excellent capacity for absorbing printing ink. On the other hand, in the case of paper made from natural pulp, and synthetic pulp having the filmy shape of conventional pulps, printing and surface processing of such paper having been remarkably difficult because a barrier property is imparted to such paper. Pulp originally having filmy shape, but becoming rod-like by contraction, and coarse pulp are good in permeability and freeness, but are weak in surface strength which tends to cause picking at the time of printing.
The following is an explanation made with reference to an emulsion flash-spinning process, which is a suitable process for producing the pulp of the present invention. This process comprises heating a polymer composi-tion mainly of a fiber-forming polymer (I) together with a solvent (II) having a boiling point lower than the melting point of (I) and being capable of uniformly dissolving at a temperature higher than said boiling point of (II), and an aqueous dispersion medium (III) at a temperature ~, 1()~141Z

higher than the regular boiling points of (II) and (III), and spinning the produced emulsion of the polymer solution through a nozzle. It is possible to produce the synthetic pulp of the present invention by making the nozzle portion of the emulsion flash-spinning process into a nozzle of a fluid in-flow type, as shown in Figure 1 of the drawings.
The process for spinning of the present invention further joins a fluid stream to the emulsion being spun as mentioned above and ejects the resulting mixture from the nozzle. The added fluid used is related to the amount of the emulsion to be ejected, and is provided in an amount 0.1 - 20 moles, preferably 0.2 - 10 moles and more preferably 1 - 10 moles based on 1 mole of both the solvent and the non-solvent in the emulsion to be e;ected. With reference to the absolute amount of fluid to be added, an amount sufficient for the aforesaid molar ratio corresponding to the discharged amount of the emulsion is used. The preferable fluld is the same fluid as the solvent in the dispersion medium used for the emulsion flash such as a liquid lower hydrocarbon, i.e. hexane, heptane, a chlorinated hydrocarbon and water. These fluids are liquid or gas at a temperature ranging from room temperature to a high temperature. Fluids other than the solvent which may be used are air, steam, hydrogen, ethane, ethylene, propane, propylene, and butane, besides nitrogen, carbon dioxide, argon and carbon monoxide of which steam, nitrogen and carbon dioxide are pre-ferred since they are cheap and have safe properties.

~ J~' ...

:109141Z

The fibrous material o~ the present invention and the pulp-like material produced therefrom have the following characteristics as compared with a fibrous material of conventional emulsion flash-spinnin~, formed without being supplied with a fluid, and a pulp-like material prepared from said fibrous material, see Figures 3 and 4.
At first, a fibrous material which is produced by flow of a fluid has a fibrillated shape and includes a plurality of superfine rod-like fibrils. A fibrous material obtained by emulsion flash-spinning is produced by forming discontinuous drops o~ superfine polymer from solution and drawing them. Therefore, the product is essentially discontinuous but there is some binding force between the resulting fibrils due to secondary intertwinement and to the basic structure of the product which is a superfine film. In this fibrous material the aggregation among the pulps is strong. On the other hand, in accordance with the present invention fibers which are formed during discharge by a supply of fluid, are sub~ected at the time of discharge to strong orientation and scattering forces, resulting in the formation of the polymer into thin rod-like shapes, Accordingly, intertwinement and binding forces between the shapes are weak, and such fibers can be beaten more easily and macerated more easily than conventional emulsion flash-spin fibers. The diameter of a pulp-like material obtained by maceration and beating is about 0.1 - 5 microns, and in many cases, 0.2 - 3 microns. The cross-sectional configuration of these materials is close to being circular and in some cases, filmy shapes are hardly seen at all. On the other hand, a fibrous material produced by using a conventional nozzle has a basically filmy shape, and pulp obtained by beating and maceration of such fibrous material also has a filmy shape.

?
~_v, Sometimes the fibrous material acquires a rod-like shape by folding or rolling in the process of beating and maceration. However, in this case, it is not possible to produce paper having the desired characteristics.
In general it is essentially difficult to convert a fibrous material having a superfine filmy shape into a fibrous material having a superfine rod-like fibrillated shape by beating. Such fibrous material has inferior beatability as compared to superfine fibrillated pulp. Superfine fibrillated pulp formed as in the present invention due to supply of a fluid when made into paper is characterized by very good dispersibility in water, excellent miscibility with natural pulp, excellent freeness and fast for~ation of a paper layer from such pulp. These are desirable characteristics because they increase the industrial paper-making speed. On the other hand, super-fine film pulp obtained by a conventional nozzle is generally poor in free-ness, slow in paper layer formation and the drainage speed is low. As a result, the water content of wet paper entering a cylinder dryer is high and the drying load is heavy.
Superfine fibrillated pulp obtained by the flowing o~ fluid as in the present invention has a favourable effect with respect to paper characteristics as well. For example, paper produced from a mixture of said synthetic pulp and wood pulp is suitably kept in a state of permeability and fluid transmission. As a result, paper made from it has good printability characteristics.
In many cases, synthetic pulp possesses hydrophobic properties which bring about the problem of lowering the surface strength of paper when paper is made from a mixture of said synthetic pulp and wood pulp.
The surface B

lO9i412 strength of paper is an important characteristic related to picking of pulp at the time of printing. As a means for increasing the surface of paper strength, internal sizing or sizing press of paper is frequently carried out. The sizing effect for advancing the surface strength of paper develops very effectively when the superfine fibrillated pulp of the present invention is used. The reason for this is not necessarily clear, but perhaps it is because the paper obtained is excellent in liquid transmission, the sizing agent permeates well and one pulp adheres well to another.
On the other hand, pulp having a filmy shape, even after being made into paper, has problems with respect to paper chacteristics. For example, the barrier property is high, the amount of water for wetting and the ink absorbing speed at the time o~ ~rinting are small, the permeation of the sizing agent is insufficient and the surface strength is not very high.
There are remarkable improvements with respect to brightness and opacity of the paper made using the synthetic pulp of the present invention as compared with paper using conventional synthetic pulp. The reason for the high brightness and opacity occurring, is not necessarily clear; however, it is considered that it may be because superfine pulp fibrils tend to cause diffused reflection, whereas the conventional superfine film pulp tends to transmit rays.
With reference to the nozzle used in the present invention the shape of the nozzle for flowing a fluid in is divided into two parts, one part is located ~22 1~9141Z
ahead of the portion for flowing the fluid in, and the second part is located behind the portion for flowing the fluid in. A typical nozzle heretofore used for emulsion flush spinning mæy be used per se as the first portion. As to the shape of such nozzle, the following articles are used, as disclosed in Japanese Patent Publication before acceptance ~o. 31916/1974 published March 23, 197~, T. Kamaishi et al. The outlet of the nozzle is normally circular in shape but may be rectangular, oval or polygonal. As the ratio of the diameter (expressed by D) to the length of said outlet (expressed by L), L/D, the range of 0.1 - 100, preferably 0.2 - 10, is used.
If the outlet of the nozzle is non-circular in shape, the ratio of the short dimension of a short side (D) to the dimension (L) is the same as in the case of the circular outlet. An inclination is permissible inside the noz-zle and sometimes there is a taper of 15 - 30 between the inlet and the outlet of the nozzle. Such taper may be created on purpose or brought about by deformation during use. The diameter of the nozzle i8 normally within the range 0.2 - 20 mm. A nozzle having a diameter less than 0.2 mm dis-charges too small an amount to be economically meaningful. A nozzle having a diameter o¢,more than 20 mm discharges too large an amount so that a fiber having a preferred shape which is slender and fibrillated according to this invention cannot be obtained thereby. When a nozzle having a non-circular ; cross-section is used, the nozzle having the same cross-sectional area as the cross-sectional area of a circular shape, having a diameter within the range of 0.2 to 20 mm is used. Sometimes, a die having at least two nozzles is used.

10914~Z

The shape of the nozzle used in the invention is shown in Figure 1. There is a discontinuous portion before and after flowing of the fluid in the nozzle from which portion the fluid enters. In Figure 1, there is a nozzle in which portion A combines with portion C (short of portion B) and a fluid inlet. m e ratio of the diameter D of the nozzle at A and ~/D may not be necessarily the same as the diameter D of the nozzle at C, but may be readily determined.
The present invention is an improvement in an emulsion flash-spinning process, the main point of which resides in the nozzle; however, preparation of the emulsion is almost conventional and is as follows.
As a fiber-forming polymer usable in the present invention, various polymers may be cited such as polyamide, polyester, polyvinyl chloride, polyacrylonitrile and polymers of the styrene series. As polymer which is especially preferable, poly-~-olefin may be cited. Within the poly-a-olefin group, polyethylene, polypropylene and poly-4-methyl pentene-l may be cited; however, a copolymer of at least 2 ~-olefin monomers will do as well. Ethylene copolymer which is produced by the copolymerization of ethylene monomer with another polar monomer such as vinyl acetate and a metal salt of acrylic acid, will also do. Again, these polymers may be modified by various polar monomers using a radical catalyst.

_ 24 -~' 1~9141Z

sesides the foregoing polymers, it is possible to add various polymers to pulp for the purpose of imparting thereto hydrophilic properties and self-adherence. For example, water-soluble polymers such as polyvinyl alcohol, polyacryl amide, polyethylene oxide, polyethylene imine, carboxymethyl cellulose and soluble starch powder or polymers obtained by random copolymerizing or block copolymerizing a vinyl monomer with each other or with other monomers, wherein said vinyl monomer has a hydrophilic group such as, for example, carboxyl, hydroxyl, amino, amide and aldehyde groups or a vinyl monomer having a group easily converted into these hydrophilic groups by after-treatment such as saponification or hydrolysis.
For example, these include maleic anhydride copolymer derivatives, acrylic acid copolymers and derivatives thereof. It is also possible to use an agent for preventing the lowering of viscosity of a polymer, an antioxidant and a weather-proofing stablizer. As for a filler, various inorganic fine powders such as, for example, silica, alumina, talc, calcium carbonate and calcium sulfate tsulfite) are added, sometimes in small or large amounts.
In order to disperse the solution in which a polymer has dissolved in an aqueous dispersion medium into a state of fine particles, a surface active agent is used. Surface active agents, such as anionic, non-ionic, amphoteric and cationic surface active agents may be cited;
however, an anionic or non-ionic surface active agent is generally preferable. As examples of such surface active agents, besides those having a relatively low lecular weight such as sodium alkylbenzene sulfonate and a high alcohol--" 109141Z

ethylene oxide adduct, a high molecular weight surface active agent may be used, such as a metal salt of maleic anhydride copolymer and vinyl monomer-grafter polyvinyl alcohol may be recommended. The content of a hydrophilic polymer is 0.5 - 40%, preferably 1 - 20% of the entire polymer including a surface active agent such as a high molecular weight surface active agent.
As a solvent for emulsion flash-spinning, those capable of uniformly dissolving a fiber-forming high molecular weight substance are used.
Specifically, methylene chloride, chloroform, hexane, pentane, heptane, ben-sene, diethyl ether, methylethyl ketone, ethyl acetate, butane, pentene, toluene, butyl acetate, cyclohexane, methyl cyclopentane and formic acid esters may be cited and they may be used in admixture. When said fiber-forming high molecular weight substance is poly-~-olefin, generally a hydro-carbon and a chlorinated hydrocarbon are preferable. A hydrophilic or water-soluble polymer is unlikely to dissolve in a solvent, but dissolves instead in the aqueous dispersion medium phase. The preferable dispersing medium is an aqueous solution which is insoluble in the aforesaid polymer solution.
Besides water, glycerine and glycol may be used and a small amount of alco-hol may be added as occasion demands. To the aqueous dispersion medium phase, a water-soluble inorganic substance is sometimes added for various other purposes.
A polymer solution phase, dissolving a polymer, disperses as superfine particles in a dispersion medium phase. As the weight ratio of a polymer solution phase ~09141Z

(expressed by a mark of 0) to a dispersion medium phase rexpressed by a mark of W), W/0, the range of 0.1 - 10, preferably the range of 0.4 - 5 is used. In order that the polymer solution phase may assume a discontinuous island phase and the aqueous solution may become a dispersion medium depending upon the properties of a surface active agent, W/0 may be above 0.4. Even when W/0 is below 0.4, there is a remarkable effect in the aqueous solution, and a remarkable difference in pulp characteristics from the case of W/O=O, namely, a flash-spinning process. For example, hecause the specific heat and the boiling point of water are high, water functions as a regenerator for removing a solvent from a polymer, supplying heat capacity at the time of flash-spinning to thereby reduce the spinning temperature. Water functions also as a carrier which carries the dissolved polymer into the pulp fiber to advance the hydrophilic properties and self-adherence of the pulp. The concentration of a polymer in the polymer solution phase is 5 - 70% by weight.
The spinning temperature is a temperature at which an emulsion system acquires a heat capacity for completely evaporating a solvent from the polymer. This temperature is at least 100C, preferably 110 - 200C. A temperature of more than 200C has little meaning from the thermoeconomic viewpoint, and at such temperature, possibly because the emulsion becomes unstable because of the high temperature, a fiber of the desired shape is not likely to be obtained.

~27-10914~2 The difference between the emulsion flash~spinning of the present invention and an ordinary flash~spinning process is as follows.
The former relates to a process for flash-spinning an emulsion in which a polymer solution is dispersed in the form of superfine particles in an aqueous dispersion medium by a surface active agent, whereas the latter is flash-spinning of a uniform solution system consisting of a polymer and a solvent therefor. The emulsion flash-spinning process has a number of merits as compared with the flash-spinning process. For example, when superfine particles of the polymer solution are ejected from a nozzle, a discontinuous fibrous material is obtained due to discontinuity of the emulsion. This remarkably facilitates conversion of such fibrous material into superfine pulp-like material by maceration and beating.
The fiber of the flash-spinning process on the other hand, is a continuous substance which cannot be beaten per se, and therefore must be cut into staple fibers. The temperature for preparing the emulsion is about 100 - 200C, preferably about 100 - 180C, which is lower by many dozens of degrees as compared with the temperature of flash-spinning. Water used as a dispersion medium remains in the spun fibers, and is quite preferably for beating and wet paper-making. The surface active agent used for preparing the emulsion remains per se in the spun fibers after spinning, and is utilized for preparation of pulp and at the time of paper-making, improving the surface properties of the paper. It is possible to add various water-soluble polymers to the aqueous phase of the emulsion. Such polymers remain on the surface of the pulp or in the interior of the pulp after spinning, and ~91~12 increase remarkably water dispersibility and self-adherence of the pulp.
A pulp obtained by flash-spinning cannot have such merits because homogeneous polymer solution phase where a poly-~-olefin-hydrocarbon solvent system is used does not dissolve a water soluble polymer, for example, polyvinyl alcohol (PVA) and resulting pulp cannot have the polymer in the interior and on the surface thereof.
Where pouring fluid is applied in flash-spinning, the main effect is only to produce cut pieces of a continuous fibrous material and the ~ drastic change in the shapes of the fiber and the pulp as in the present invention is not seen. As a result of inflow of a fluid in the system of emulsion flash-spinning, finely fibrillated fibrils are obtained, and such fibrils have shapes and properties which are remarkably different from those of conventional fibers. In the invention of emulsion flash-spinning using fluid flowing nozzles, the mechanism by which the excellent fibrous materials are produced is believed to be as follows: in an autoclave, polymer solution particles are dispersed in a non-solvent such as water under high temperature and pressure so as to form an emulsion. The emulsion is then introduced into the nozzle. The evaporation of the solvent from the emulsion occurs because the pressure in the nozzle is lower compared to the pressure in the autoclave.
Therefore the separation of the polymer from the emulsion is brought about, but the separated polymer which has not adequate orientation yet, are suspended in the non-solvent such as water as particles.
When the separated polymer particles which are suspended in the non-solvent come in contact with poured fluid, they are subjected to a vigorous orienting force and scattering force. The polymer flowing through the nozzle solidifies into fine fibrous structure in outer atmosphere. The remarkable change of the fiber shape occurring as~a result of the scattering force applied at this time suggests that a change has taken place which is different from the cutting effect which is encountered in flash-spinning at the moment the fiber is formed into a continuous fibrous material.

The present invention will hereinafter be furtber explained by reference to the ~ollowing examples. However, it is intended that the scope of the present invention shall not be limited thereby. The term "parts" in the following examples designates "parts by weight" unless otherwise specifically stated.
Exam~le 1 100 parts of high density polyethylene (*"Hizex" 2100 LP, manufactured by Mitsui Petrochemical Co. Ltd., Japan) and 10 parts of poly-vinyl alcohol (*"Gosenol" NM-14, manufactured by Japan Synthetic Chemical Co. Ltd.) together with 0.1 part of *"Irganox" 1010 (manufactured by Ciba-Geigy Ltd., Switzerland) were added to a solvent - dispersion medium system consisting of 1,500 parts of methylene chloride and 80o parts of an aqueous solution containing 5 parts of sodium sàlt of maleic anhydride - styrene -methyl methacrylate - lauryl methacrylate (molar ratio 50/30/10/10) co-polymer and made into a slurry. Thereafter, the temperature of the slurry was raised while stirring to prepare an emulsion at 140 C. This emulsion was e~ected from a specifically constructed 2-fluid nozzle similar to Figure 1 of the drawings. The nozzle A had a ratio L/D=2 and D=2 mm ~ was used.
A nozzle C having an angle of an open part, 1-3 ~ Ql=15mm, Q2=20mm and ~3=3nmm was connected to the fluid feed portion B (Figure 1).
As the fluid being fed from feed portion B (Figure 1), saturated steam under pressure of 20 kg/cm2 was used. The fiber obtained was an aggregation of superfine fibers easily dispersible in water *Trademark - 30 -containing a large amount Or an aqueous solution, a greater part o~ which could be easily removed by a thickener.
The superfine fiber so obtained was beaten into a pulp-like material. For beating, a Sprout/Waldron type single disc re~iner (manufactured by Kumagaya Riki Co. Ltd., Ja~an) was used. At a pulp con-centration of 0.5%,the clearance between rotating blade and fixed blade was successively changed from 0.3 mm to o.6 mm, 0.4 mm, 0.2 mm, 0.1 mm, and 0.01 mm and the pulp slurry was caused to pass therethrough 1, 2, 2, 2, and 5 times, respectively.
The dispersibility in water of the pulp produced was very excellent.
When this pulp was screened according to JIS P 8207, distribution of the sizes thereof was checked and showed the following distribution, Distribution of Screened Fractions 24# on 10.1%
42# on 39.5%
80# on 30. 6%
150# on 15.8~
150# pass 4.0%
On the other hand, as a comparative example, by a process identical to the aforementioned process in composition of and conditions for preparing an emulsion, but using the spinning process only by using the nozzle A only without the portions B and C of Figure 1, spinning was carried out. The resultant fiber was a soft, massive aggregation, which could be easily torn to pieces. When dispersion of this aggregation in water was attempted, it did not disperse in the slurry state and its shape did not crumble. This fibrous material was beaten the same as mentioned above to obtain the following pulpS.
Distribution of Screened Fractions 24# on 3.0%
42# on 20.4%
80# on 32.3%
150# on 39.3%
150# pass 5.o%
The dispersibility in water of the pulps was excellent as in the aforementioned pulp.
Using pulps prepared in this way, paper was made from a mixture of natural pulp and 20% of this pulp according to a known method. The physical properties of the pulp and such paper samples are shown in Table 1.
The following facts are under~tood from Table 1.
(1) The pulp of the present invention has a very short drainage time, and corresponding thereto, the freeness is of high degree.
(2) The opacity of the pulp of the present invention is remarkably high. The relation between the opacity (y, %) and the surface strength (x, A) satisfied y>l.5x + 85 and in the case of a comparative example, said relation satisfied y~l.5x + 85.

109~412 Table 1 Physical Properties of Synthetic Pulp and Paper Made Frcm Mixed Pulp Containing 20% Synthetic Pulp Pulp of Pulp of Items PresentComparative Invention Example Drainage time of pulp (sec) 20% mixing 7.0 22.0 100% synthetic pulp 10. 6 550.0 blank (100% wood pulp) 8.3 8.3 CSF (cc) (100% synthetic pulp 175 10>
Basis weight of paper made from mixed pulp containing50.7 51.1 20% of the 2ynthetic pulp Breaking length (km) 4) 4.3 5.5 Elongation (%) 5.1 7.0 Opacity (%) 3) 78.5 64.o Brightness (%) 3)85.6 80.0 Surface strength 8A lOA
(D-wax ~o.) 2) Air permeability (sec) 5) 15 840 ~OTE
1) The wood pulp used was of ~BKP/LBKP=1/4 having a .~ freeness of 400 cc. The physical properties of paper of 100% wood pulp were: breaking length of 4. 8 km, elongation of 6.4%, opacity of 62.2%, brightness of 82.5%, degree of air permeability 7.4 seconds and D-wax ~o. lOA when the basis weight was 51.3 g/m .

2) Surface strength is shown by a value of D-wax No. tDennison wax number) according to JIS P-8129 and corresponds to a Z-axis strength of paper.
The larger the value, the greater is the surface strength.
3) Brightness and opacity were measured by an integral sphere-type photo-meter (manufactured by Japan Precision Industry Co., Ltd.) in accordance with JIS P-8136. The higher the values, the higher the brightness and opacity.
4) Breaking length was measured using a highly sensitive tensile tester (manufactured by Toyo Sokki Co., Ltd., Japan) in accordance with JIS P-8113.
5) Air permeability was measured by a Gurley densometer~manufactured by Kumagaya Riki Co., Ltd.~ in accordance with JIS P-8117.
t3) The synthetic pulp of the present invention is low in degree of air permeability. On the other hand, the synthetic pulp of the comparative example is great in barrier property (ability to bar). When the ratio of the synthetic pulp in the mix is raised, the difference between the two becomes even greater.
The foregoing results are based on the differences in structure of the two synthetic pulps. Figure 2 shows (900 x) the structure of pulp produced according to Example 1. The structure of conventional pulp viewed under a scanning type electron microscope, is a filmy structure; the synthetic pulp having a ratio of a transverse dimension (Ql) to a longitudinal dimension (Q2)' (Ql/Q2)' of less than 10 on a cross-sectional configuration taken at a right angle to the fiber axis defined in the text of this specification is hardly found.

10914~2 Although the structure is termed filmy, it is not flat, but instead branches in a complicated fashion and occasionally portions show a honey-comb structure.
On the other hand, in the aforesaid pulp (Figure 2) of the present invention, there was hardly any filmy structure. In cross-section, there was no configuration in which the Ql/Q2 ratio exceeded 10 and at least 90% of the configuration had a Ql/Q2 ratio of below 5. The pulp was rod-like, on a cross-sectional configuration taken at a right angle to the fiber axis. In the case of a tangent being drawn in contact with two convex portions corresponding to the most concave portion on the pulp surface, the shortest length (Ql') from the tangent to the most concave portion was less than 1/2 the width of the cross section of the fiber (Ql) and there was no pulp whose value of Ql' was close to the value of Ql Almost all average diameters of pulps are determined at the time of spinning, and the dimensions change only when the pulp is unraveled by beating or cutting in a lengthwise direction. According to observation under a scanning-type electron microscope having a magnification of 900 times (see for example Figure 2),(also may be observed by an optical micro-scope) when the average diameter of Pulp (~ Q1) was measured by taking into account the adhesion factor of one pulp to another, almost all the average diameters of pulps are within the range of 0.1 - 3 microns. The specific surface area of this pulp was 9.8 m2/g according to a BET process. It is apparent at a glance that the outer shape of this pulp is different from that of the conventional ~)9~412 pulp. The shapes of pulps are uniform, reminding one of an aggregation of wires which differ in thickness. The conventional synthetic pulp joins to-gether while it varies continuously from strands which are very thick to strands which are very thin, and this conventional synthetic pulp is remark-ably non-uniform in shape and the distribution of the pulp is broad. In this respect, conventional synthetic pulp is very different from the syn-thetic pulp of the present invention. The specific surface area of the pulp of the comparative example was 10.3 m2/g. The width of the pulp, as measured by microscopic observation in the aforesaid manner, reached up to 100 mic-rons; however, the pulp was generally very thin and almost all its thick-nesses were within the range of 0.1 - 1 micron.
When a hydrophilic polymer (polyvinyl alcohol or PVA in this ex-ample) which was distributed on the surface and the interior of the pulp was checked by dyeing the ultra-thin sections of a cross section and longitudinal cross section with heavy metal and the subsequent observation by a trans-mission-type electron microscope (15,000 - 60,000 magnification), PVA was distributed everywhere on the surface and in the interior of the pulp, and there was no great difference between the pulp of the present ir.vention and the pulp of the comparative example. In a cross-sectional configuration taken at a right angle to the fiber axis, PVA formed the structure of islands of irregular shapes having a thickness of 0.0015 - 0.35 micron. On a longi-tudinal cross-sectional area parallel to the fiber axis, PVA was arranged as cont~nuous or intermittent striae in the direction of the fiber axis.

1a91412 The PVA content of the pulp was determined by boiling and reducing a sample with propionic anhydride in a 1, 2, 3, 4 - tetra hydronaphthalene/N-methyl pyrrolidone solvent to thereby make -OH groups into propionate, and titrating the consumed pm pionic anhydride. The PVA content of the pulp of the present invention was 3.8% and the PVA
content of the comparative example was 4.3%.
Example 2 Spinning was carried out while varying the compositions of the polymers and the spinning conditions to check the physical properties of pulp and paper samples made therefrom. Besides polyethylene, polypropylene (PP), a sodium salt of an ethylene - acrylic acid copolymer, and an ethylene-vinyl acetate copolymer (EvAc) were used as polymers.
As a solvent, besides methylene chloride, hexane was used.
In the following Table 2, the spinning conditions are shown en masse.

~091412 Table 2 Conditions of Tests . .. _ _ .. _ ._ Composition of Surface Solvent Poured Emulsion flush polymer (part) Active dispersion fluid spinning Agent medium (parts) tOmperature (part) ( C) . . . .
1 2 3 Solvent Water Kind Part Poly- _ VA Sodium CH2C12 1600 Steam 14 140 pro- 15 dodecyl under pylene benzene 1300 pres-100 sulfo- sure nate of 4 2cm2 ... _. ...... _ .... _ Steam 100 ~ ~ VlA DBS 4 1H320012 1600 asame 13 140 _ _ - ~ ~ ~ .. ~ = above ST-MAH CH Cl Heated PP ~vAc VA copoly- 2 2 1600 nitro- 9 145 ôO 20 15 mer 1300 gen _ 4 _ _ HDPE~ EAA VA ST-MAH Hexane 1600 Steam 140 ~~ 35 copoly- 1000 nitro-~oIy- mer gen mer salt mixed ~al 4 fluid under18 _ _ pres-HDPE Same VA Same Same 1600 sure 140 85 as 10 as as of abov above above 22ke/
_ cm HDPE Same VA Same Same 1600 (molar as 20 as as ratio 140 abov~ above above 1:4) . ....
NOTE
1) As polypropylene (PP), "*Noblene" HS, (manufactured by Mitsui-Toatsu Co., Ltd., Japan) was used.
2) Polyvinyl alcohol (PVA is the same as that used in Example 1.
3) *EvAc, containing 8% by weight of vinyl acetate, manufactured by Mitsui Polychemical Co., Ltd., Japan.

*Trademarks - 38 -4l2 4) EAA: sodium salt of an ethylene - acrylic acid copolymer manufactured by DuPont, obtained from Mitsui Polychemical Co., Ltd.
5) HDPE is a high density polyethylene the same as that in Example 1.
6) DBS is sodium dodecylbenzene sulfonate manufactured by Sanyo Kasei Co., Ltd., Japan.
7) St-MAH copolymer is an equimolar mixture of a styrene -maleic anhydride - methyl methacrylate copolymer - sodium salt - calcium salt.
8) Nitrogen at 150 C was used.
9) The amount of a fluid flowing is indicated in parts by weight per part of spun fiber by weight.

Beating and paper-making of fibers obtained by spinning were carried out in exactly tbe same way as in Example 1 and the wood pulp used was also the same. Micro-scopic observation of pulp was carried out by the method described in the text of this specification and as in Example 1, and measurements of the physical properties of the pulp and the paper were carried out in the same way as in i Example 1. The measured results are shown in Table 3.
From these tests results it can be seen that a phenomenon, the same as that of polyethylene in Example 1, was observed in the case of polypropylene. In the case of conditions meeting the requirement of the present invention by steps other than the change of a blended polymer, the amount of PVA added, the kind of solvent and the kind of fluid, results showing excellent physical properties of the 109~41Z

pulp and paper made therefrom were obtained.
NOTE on Table 3:
1) The numbers correspond to the numbers of experimental conditions in Table 2."A" shows the results obtained by carrying out spinning under conditions exactly the same as those in Table 2. "B" shows the results obtained by carrying out spinning under conditions exactly the same as in Table 2 except for returning thenozzle to the conventional nozzle (portion A only in Figure 1).
2) In case "B" the width (Ql) on a cross-sectional configuration taken at a right angle to the fiber axis was difficult to define, and therefore, it was shown by thickness (Q2).

_ 40 -1C~9141Z

Table 3 Physical Properties o~ Pulp and Paper Made From Mixed Pulp Cont inin~ 20% of the PulP
. Measured items . ..... 2 3 4 ~
.. ...... _ A B A B
Drainage time of pulp (sec) 20% mixing 6.8 18 6.9 7.2 7.5 7.8 20 8.o 100% synthetic 5.0 62 4 5.3 6.5 80 162 12.0 pulp ¢SF of pulp (100% 415 81 515 405 45 300 65 213 synthetic pulp) ~c:) _ I
Basis weight of pape 49.5 50.3 48.9 51.1 50.3 49.8 48.9 50.6 made from mixture containing 20% of (gm ) Breaking length (km) 3.5 4.5 2.8 4.7 4.3 4.5 5.1 4.6 Elongation (%) 4.2 4.9 3.1 5.2 5 5 0 6.5 5.3 Opacity (%) 84.2 75.5 84. 82.5 81.678.5 61.3 78.0 Brightness (%) 85.6 86.1 86.3 83.8 83.8 82.978.9 83.7 Surface strength 2A 4A <2A 6A 8A lOA llA lOA
(D-wax ~o.) Air permeability 13 86 12 14 16 17 295 17 PVA content (%) 5.2 6.8 0.4 5-5 2.0 3.8 6.1 7.2 Size of PVA par- 0.002 0.002 _ 0.0019 0.0015 0.002 0.001 8 0.001 (thickness) (~) -0.51 -0.63 -0.58 -0.32 ~0.39 0.41 -0.58 BET speci~ic surface 13.1 20.6 18. 22.3 14.213.1 8.9 10.4 area of p( ~/ ) Shape of P Ql/ 2 1/ 2 above 1.5 2.6 2.3 3.1 a~ove 2.0 . above, 10 10% 7 . 90% ~3 Uneveness of P* <1/2_ 0.2 0.35 0.18 0.24 _ 0.22 Ql/Ql Width of P* (Ql) 0.1- (0.1- 7.8 7.8 2.3 3.1 ( 5 2.5 (~) 2 ) ~1.

` 109~41Z

NOTE
P* = cross-sectional area at a right angle to the fiber axis Example 3.
An emulsion was prepared using mainly polyethylene as a fiber forming polymer, adding a composition consisting of PVA, a stabilizer, etc., as a hydrophilic polymer to the system of a solvent and a non-solvent consisting of hexane - water; further adding a surface active agent and raising the temperature while stirring. A 5-liter capacity stainless steel autoclave was used as a container. The temperature was raised by steam and stirring was carried out by electromagnetic induction. On the bottom of the autoclave, an opening for discharging emulsion was provided, beyond which a valve and a nozzle for in-flow of fluid (see Figure 1) were also provided. A nozzle exactly the same as that in Example 1 was used. The amount of hexane and water were combined to equal 3 liters altogether, and as a stabilizer, *Irganox 1010 (manufactured by Ciba-Geigy Ltd., Switzerland) (tetrakis methylene-(3.5-di tertiary butyl-4-hydroxy-hydrocinnamate) butane), -*DLTDP (manufactured by Yoshitomi Pharmaceutical Co., Ltd., Japan) and "*Yoshinox" -BHT- (manufactured by Yoshitomi Pharmaceutical Co., Ltd.,) (2,6-di tertiary butyl-4-methyl phenol) were used in amounts of 0.1% by weight, 0.2% by weight and 0.2% by weight, respectively, based on poly-ethylene. As a fluid, steam and nitrogen gas were used. The experimentalconditions were as shown in Table 4. All fibrous materials obtained by spinning * Trade Marks .~

under these conditions were aggregations of staple fibers in which superfine fibrils were intertwined.
These fibrous materials were beaten under the same con-ditions as in Example 1 to prepare pulp, and paper was made from a mixed pulp consisting of 20% of said pulp and 80% of wood pulp and the resulting mixed paper was evaluated.

1(~9~412 Table 4 Test Conditions in Exam~le 3 Poly- PVAOthers Spinning Conditions Change of Kind Change ethyl- ( e ) ( g) ._ _ ~ conditions of ele-ene Surface Spin- /o of a fluid fluid ments (g) active ning ratio inflow agent tem- nozzle (g) pera-t(UCr)e . . . .__ _ 78 2.3 _ A4 145 1.8 Standard S
conditions 78 o.78 _ A4 145 1.8 .. S PcVoAn_ trnation 100 1.5 _ A4 145 1.8 ll S Polymer trnateiOnn, 100 1.5 _ B4 145 1.2 ll S S/O, agtiftaee 2 _ A3 140 0.4 n N ~luid 2 _ A3 140 0.2 ~- S W/O
100 2 _ A4 145 1.2 Clearance Clear-h-3 mm hnce 2 _ A4 150 1.0 Opening S Opening a~glgO ~an2gle 2 _ A4 150 1.0 02=15 S Penleng a~n2g 4 _ C4 170 o.7 Q2=1 N faceSur~

agtentve afnluid 68 2.4 "*Surline" A4 145 1.2 Standard S Polymer A conditions timonPsi~
2.3 Poly-4_ A4 145 1.2 .. Polymer methyl compo-_ pentene-l . . sition *Trademark - 44 -NOTE
1. Polyethylene was used the same as in Example 1.
2. As PVA, "*Gosenol NH-185", manufactured by Japan Synthetic Chemical Co., Ltd. was used.
3. "*Surline A" was the same as the ethylene - sodium acrylic copolymer used in Example 2.
4. Poly-4-methyl pentene-l was that obtained from Mitsui Petrochemical Co., Ltd.
5. Surface active agent A was an equimolar mixture of sodium salt and calcium salt of maleic anhydride - styrene - methyl methacrylate copolymer. Surface active agent B was an equimolar mixture of sodium salt and calcium salt of dodecylbenzene sulfonic acid. Surface active agent C was a 1:1 mixture of a polypropylene glycol (3c) _ ethylene oxide (150) adduct, and a stearyl alcohol - ethylene oxide (7) adduct triester phosphate by weight.
6. The standard conditions of a nozzle were: in Figure 1, portion A:
nozzle portion L/D=2, D=2 mm ~ and a2=10.
7. Kind of fluid: S: heated steam: N: pressurized nitrogen. Under the standard conditions of the nozzle, the amount of flow of S and N

is (2~10) x 103 mole/hr.

Table 5 Physical Properties of Paper Made From Mixed Pulp Containing 20% Superfine Fibrillated PU1P
. _ ,. ~
~o. Drainage Basis Surface Brightness Opacity Breaking Bulk time weight strength length density (sec) of (D-wax No.) (%) (%) (km) (g/cm3) paper ~ _ 1 5.4 51.2 7A 85 79 4.2 o.55 2 5-5 50.8 6A 83 81 4.2 0.52 3 6.9 51.0 7A 83 78 3.7 0.62 4 7.6 49~5 7A 81 77 4.1 o.64 5.7 49.2 7A 87 76 4.2 0.61 6 5.3 50.1 7A 87 74 4.3 0.63 7 7.0 49.8 8A 77 73 3.a o.64 8 6.2 51.6 7A 87 79 4.2 0.61 9 6.7 52.0 7A 84 80 4.3 0.58 7.3 51.5 7A 83 76 4.1 o.59 11 7.3 52.3 lOA 84 79 4.5 0.58 12 5 7 51 5 8A 86 T8 3 . 6 O . 57 ~10914:12 Table 6 Physical Properties of Superfine Fibrillated Pulp , .. _ __ ., ~
No.* 1 2 3 4 (1) (4) (11) (12) ~ ~ === -- . . . - . -~.~. . _ PVA content (%) 1.9 0.9 2.3 2.7 Size of PVA particles 0.0015- 0.002- 0.0015- 0.005-(thickness) (~) 0.43 0.28 o.o8 0.45 BE~ specific surface area 10.4 8.9 12.4 11.6 Shape of P** (Ql /Q2) 1.6 2.0 1.3 1.4 Uneveness of P (Ql / 1) 0.1 0.2 0.15 0.1 Width of P**Ql (~)0.1 6 3.80.1 5 3.9 .

NOTE
No.*=Number (corresponding to number of Tables 4 and 5) P**=cross-sectional configuration taken at a right angle to the fiber axis NOTE
1. The results of Table 6 are for mixed paper made by beating and paper-making of fiber spun under conditions of Table 5.
Numbers correspond to those in Table 4.
2. Wood pulp used for making mixed paper was of NBKP/LBKP=1/4 having a freeness of 400 cc. A sample having a pulp density of 10% was beaten in a PFI mill (manufactured by Kumagaya Biki Co., Ltd.) in accordance with CSF (Canadian Standard Freeness) C-7.
3. Conditions for beating synthetic pulp: in accordance with CSF C-7, a slurry consisting of 10 liters of water combined with 5-10 g of pulp was beaten by a high concentration lOg~412 refiner (manufactured by Kumagaya Biki Co., Ltd.). A
pulverizing blade was used. Clearance and passing fre-quency: 1 mm x 2 times, o.8 x 2, o.6 x 2, 0.4 x 2, 0.2 x 2, 0.1 x 2 and 0.01 mm x 5 times.
4. Drainage time: in accordance with TAPPI standard method, T-221, 3 g of a mixture of synthetic pulp and natural pulp was dispersed in 12 liters of water and drainage time of water in a square type paper-making machine was measured.
Pulp having a short drainage time (second) may be considered as having good freeness.
The results of Table 6 show that by mixing superfine fibrillated pulp with wood pulp, the opacity and brightness are remarkably improved as compared with paper made from 100% wood pulp. Incidentally, the opacity of the same basis weight of paper made from 100% wood pulp is 61%
and its brightness is 78%. It is apparent from a comparison with Table 7 that the superfine fibrillated pulp and n&xed paper made therefrom have remarkable characteristics as compared with pulp and paper made using the conventional nozzle. The drainage time of mixed pulp containing 20~ of the pulp of the present invention is remarkably shortened.
The surface strength of the paper of the present invention is somewhat better, and when size press of paper by a sizing agent is carried out, clearer difference is brought about.
There are apparent differences in brightness and opacity of paper and the effect of the present invention is remarkable.
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' - ~8 -~ 10~141Z

Comparative Example 1 Using a conventional nozzle having no fluid inflow portion (in Figure 1, a nozzle having no portions B and C, consisting of portion A
only), emulsion flash-spinning was carried out. The experimental method was almost the same as in Example 3. The results thereof are shown in Table 7, in which each run corresponds to the runs in Tables 4 and 5. The com-parison withthe corresponding results in Example 3 is described in Example 3.
Table 7 Test Results of Mixed Paper Made From Mixed Pulp Containing 20% of PulP Made by Us_n~a Conventional_Nozzle No. Corre- Drain- Basis Surface Bright- Opacity BreaklnB Bulk .
sponding age weight strength ness (%) length dens~ty No. in time ( / 2) (D-wax (%) (km) (g/cm ) T4abanedS5 (sec) g m No.) .__ 1 4 16.2 51.0 7A 75 72 4.5 0.60 2 5 19.5 49 5 7A 76 69 4.6 0.71 3 11 21.0 50.1 8A 79 65 4.8 0.70 4 12 17.5 49.8 6A 81 71 4.3 ~.65 _ NOTE
1. The corresponding numbers in Tables 4 and 5 show that except for the nozzle being a conventional nozzle, spinning condi-tions are exactly the same as those of the corresponding num-bers in Tables 4 and 5.
2. For the spinning conditions and measuring method of physical properties of paper, reference should be made to Tables 4 and Exa~ple 4 80 g of polypropylene powder (the same as that used in Example 2) together with 4 g of a metal salt of a methyl methacrylate - maleic an-hydride copolymer as a surface active agent and 0.4 g of a heat stabilizer, "*Yoshinox - BHT", (manufactured by Yoshitomi Pharmaceutical Co., Ltd.) were mixed with 1.5 liters of methylene chloride and 1.4 liters of water.
m e resultant mixture was charged in a 5-liter capacity autoclave and e~ected by the same method as in Example 3. The temperature of the emulsion obtained was raised to 140 C and the conditions of the fluid inflow nozzle were the same as the standard conditions of No. 1 in Example 3. The superfine fibrillated fibrous material produced was beaten by a refiner under the same conditions as in Example 3. The beating of the pulp was further improved and was carried out with greater ease as compared with that of a material prepared by a conventional nozzle short of a fluid inflow nozzle. 20% of the pulp so-obtained was mixed with wood pulp and the physical properties of paper made from said mixed pulp were measured by a similar method. However, paper was pressed by a calendar into a Beck's degree of smoothness of about 60 sec/10 cc. The results are shown in Tables 8 and 9. The measured results of the physical properties of paper made from pulp spun by using a conventional nozzle are simultaneously shown as Comparative Example 2 in Tables 8 and 9.

* Trade Mark B

Table 8 - Measured results of the physical properties of paper made from mixed pulp containing 20% of superfine fibrillated polypropylene pulp . Measured items Example 4Comparative .
Example 2 1. Drainage time (sec) 6.2 9.0 2. Basis weight (g/m ) 50.2 51.0 3. Bulk density (g/cm3) O.56 O.57 4. Degree of smoothness (sec/10 cc 62 58 5. Brightness (%) 5 83 6. Opacity (%) 84 78 7. Oil absorbtion degree (sec) 45 103 8. Air permeability (sec)11 110 9. Surface strength (D-wax No.) <2 2 Note:
1. Degree of smoothness was measured according to JIS
P 8119 (TAPPI T 479). Air permeability was measured according to JIS P 8117 (TAPPI T 460). Oil absorbing degree was the time required (sec) for the paper to absorb 4.9 micron liters of light oil dropped to the surface thereof.

Comparative Example 2 Spinning was carried out under exactly the same conditions as in Example 3 except that a conventional noz~le was used in order to obtain a massive discontinuous fiber. This fiber was beaten by a refiner under the same conditions as in Example 3. As compared with the fibrillated fiber in Example 4, beating was relatively difficult and -'` 109~41Z
. , some fibers adhered to the refiner and were not beaten. The pulp was treated the same as in Example 4 and the values o~ physical properties of paper made therefrom are shown in Tables 8 and 9.
Table 9 Comparison of physical properties of the pulps Measured items Example 4 Comparative Example 2 PVA content (%) 2.6 3.0 Size of PVA particles (thickness) (~) 0.002 - 0.38 0.002 - 0.42 BET specific surface area (m2/g) 14.8 16.5 Shape of P* (Ql/Q2) 2.8 above 90% > 10 Unevenness of P* (Ql /Ql) <1/2 Width of P* Ql (~) 8.1 (thicknes)s Q2 :
,,:
~ote '~
P*=cross sectional area at a right angle to the fiber axis.
Example 5 50 g of polypropylene powder (the same as that used in Example 2), ;~ 10 g of an ethylene - vinyl acetate copolymer, "*Evaflex" 560, (manu-factured by Mitsui Polychemical Co., Ltd.) and 5 g of polyvinyl alcohol I (the same as that used in Example 1) together with 5 g of a metal salt of 1 20 a styrene - maleic anhydride - methyl methacrylate copolymer as a surface ¦~ active agent and 0.5 g of a heat stabilizer, "*Yoshinox" BHT (manufactured by Yoshitomi Pharmaceutical Co., Ltd.) were mixed with 1.ô4 liters of water and 1.15 liters of hexane. The resulting mixture was charged in a 5-liter (inner capacity) autoclave and an emulsion at 140 C was ejected ' .
* Trade Marks , ~ .

. .

under the standard conditions of the nozzle of Example 3. An emulsion ob-tained by using a nozzle with conditions restored to the conventional con-ditions was ejected under exactly the same conditions. There was a great difference in beatability between the two, with the pulp obtained according to the process of the present invention being more easily beaten as in the examples of Table 8. As to the physical properties of pulp and paper made therefrom, there w~s a similar difference. When the process of the present invention and the conventional process were compared in mixed papers having a basic weight of 50 g/m , the drainage time of pulp was 65 seconds in the former and 108 seconds in the latter. The opacity values were 82.5% in the former and 78.o% in the latter. The degree of air permeability was 12.5 sec-onds in the former and 12.3 seconds in the latter. These papers were made from mixed pulps consisting of the synthetic pulp and wood pulp, containing 20% of the synthetic pulp.
The PVA contents in the pulp were 4.2% in the process of the present invention and 5.0% in the conventional process, the surface strength being 3A in the former and 4A in the latter. The size (tbickness) of PVA particles on a cross section taken at a right angle to the fiber axis in the process of the present invention was 0.002 - 0.32 micron (average 0.11 micron). The configuration of a cross section taken at a right angle to the fiber axis of the pulp, Ql/Q2' was 3.0, the unevenness of said cross sec-tion, Q1'/Ql was below 1/2 and the width of said cross section, Q1 averaged 6.9 microns. The PVA particles of pulp according to the conventional process showed a value similar to that mentioned above, however, the pulp had a filmy structure and a shape similar to that obtained using the convention~l nozzle of said example.
Comparative Example 3 Using the fluid inflow nozzle used in the present invention, a fiber was fractionated by flash-spinning. The spinning was carried out using the apparatus of Example 3 per se and the nozzle conditions were the standard 1~9141Z
conditions. Polyethylene and polypropylene as described in Examples 3 and 4, respectively, were used, 200 g of which, together with 1 g of a heat stabilizer, was added to 2.5 liters of hexane. The resulting mixture was stirred and its temperature was raised. In the case of polyethylene, spin-ning was carried out at ejecting te~peratures of 130 C, 155 C and 175 C, and in the case of polypropylene, spinning was carried out at an e~ecting temperature of 175 C. In each case, a fibrous material became fine by inflow of a fluid. Because both polyethylene and polypropylene are hy-drophobic and not compatible with water, an anionic surface active agent was added. Yet, the pulps floated and were unlikely to disperse uniformly in water. This inclination was especially strong in the case of polypropyl-ene. In the case of the process of the present invention, such phenomenon was not seen at all. The pulps so-obtained were made into paper containing 20% of the pulp of the present invention and 20% of the conventional pulp, respectively, by the process of Example 3 and the physical properties of thi8 paper were measured. The results are shown in Table 10. As can be seen from Table 10, compared with the pulp and paper made therefrom of the present invention prepared by an emulsion flash-spinning process, results inferior in optical properties and all properties relating to strength were obtained by ~ 54 --- 109141z the conventional process. That in the case of flash~spinning, these physical properties were not especially improved by inflow of a fluid is considered to indicate that the superfine shape of fiber was not improved very much by the fluid inflow nozzle. It is a matter of course in the case of flash-spinning that the fiber becomes fine as described in Japanese patent publication before acceptance No. 24035/1973. Published March 28, 1973, Carlo Raganto e* al.
Table 10 Test results of papers made from mixed pulp containing 20% of superfine pulp obtained by flash-spinning _ Polyethylene Polypropyle~e spun at 175 C
Measured items Spun at Spun at Spun at 1. Basic weight (g/m2)46.4 47.4 48.3 47.9 2. Bulk density (g/cm )0.41 0.49 0.49 0.36 3. Breaking length (km)3.0 3.2 2.8 2.7 4. Opacity (%) 69 74 75 72 5. Brightness (%) 85 86 84 86 6. Surface Strength 3A 3A 3A ~2A
(D-wax No.) Note 1. As to the methods of measuring the characteristic values, please refer to the aforesaid examples.

' -.~

Claims (25)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A synthetic pulp-like material comprising a fibrillated fibrous material comprising a hydrophobic polymer and a hydrophilic polymer which are substantially incapable of dissolving simultaneously in a solvent for said hydrophobic polymer, said hydrophilic polymer viewed on a cross-section taken at a right angle to the fiber axis of said fibrillated fibrous material as-suming a structure of substantially non-circular irregular islands having a thickness which is less than about 1 micron, wherein (a) when viewed in longitudinal cross-section parallel to the fiber axis of said fibrillated fibrous material, the same hydrophilic polymer is arranged in the direction of the fiber axis in the form of continuous or intermittent striae, and (b) substantially a majority of said fibrillated fibrous mat-erial has a dimension equal to or less than about 15 mm and the shortest dimension is greater than the thickness of the fiber, and wherein (c) when viewed in cross-section taken at a right angle to the direction of the fiber axis of said fibrillated fibrous material, the ratio of the transverse dimension (?1) to the longitudinal dimension (?2), (?1/?2), is within the range of about 1 - 10 and the longitudinal dimension is equal to or less than about 10 microns.
2. A synthetic pulp-like material according to claim 1, wherein said longitudinal dimension (?2) does not exceed 5 microns.
3. A synthetic pulp-like material according to claim 1, wherein said ratio of the transverse dimension (?1) to the longitudinal dimension (?2), (?1/?2) is within the range of 1 - 5.
4. A synthetic pulp-like material according to claim 3, wherein said longitudinal dimension (?2) does not exceed 5 microns.
5. A synthetic pulp-like material according to claim 1, wherein said transverse dimension (?1) does not exceed 10 microns.
6. A synthetic pulp-like material according to claim 1, wherein the amount of said hydrophilic polymer is about 0.5 - 40% by weight of the entire polymer component.
7. A synthetic pulp-like material according to claim 1, wherein said hydrophilic polymer viewed on a cross-section taken at a right angle to the fiber axis of said fibrillated fibrous material has a structure of sub-stantially non-circular irregular islands having a thickness of about 0.1 -0.001 micron.
8. A synthetic pulp-like material according to claim 1, wherein said hydrophobic polymer is poly-a-olefin.
9. A synthetic pulp-like material according to claim 8, wherein said poly-a-olefin is polyethylene, polypropylene or a copolymer containing ethyl-ene or propylene.
10. A synthetic pulp-like material according to claim 8, wherein a metal salt of an ethylene-vinyl acetate copolymer or an ethylene-acrylic acid copolymer is included.
11. A synthetic pulp-like material according to claim 1, wherein said hydrophilic polymer is completely or partially saponified polyvinyl alcohol or a copolymer thereof.
12. A synthetic pulp-like material according to claim 1, wherein said hydrophilic polymer is (a) polyacrylamide, polyethylene oxide, polyethylene imine, carboxymethyl cellulose or soluble starch, or (b) maleic anhydride copolymer, acrylic acid copolymer or an alkali metal salt of these copolymers.
13. A synthetic pulp-like material according to claim 1 having a specific surface area of above 1 m2/g, a drainage time of less than 50 seconds and the opacity (y%.sigma.) and wherein the surface strength (xA) of paper obtained when 20% of said synthetic pulp-like material is mixed with wood pulp satisfies the relation of Y? -1.5x + 85
14. A synthetic pulp-like material according to claim 1, wherein there are substantially no voids in a cross-section taken at a right angle to the fiber axis of said fibrillated fibrous material, and wherein sub-stantially all of such voids as are present have closed shapes distributed as islands with the sizes of such voids not exceeding about 1/2 of the fiber diameter.
15. In a process for preparing a synthetic pulp-like material, the steps which comprise emulsion flashing an emulsion substantially containing (a) a fiber-forming hydrophobic polymer and a hydrophilic polymer which is substantially incapable of dissolving with a solvent for said hydrophobic polymer (b) the solvent for said hydrophobic polymer which has a boiling point lower than the melting point of said hydrophobic polymer, and (c) an aqueous dispersion medium into a low pressure zone through a nozzle, and flowing a fluid into the nozzle portion in an area of reduced pressure.
16. A process according to claim 15, wherein said fiber-forming polymer is a hydrophobic polymer, and a hydrophilic polymer is further added.
17. A process according to claim 15, wherein the amount of said fluid being flowed in is within the range of 0.1 - 20 moles based on 1 mole of the solvent plus the aqueous dispersion medium in the emulsion.
18. A process according to claim 15, wherein said fluid is said solvent or aqueous dispersion medium, or a mixture thereof.
19. A process according to claim 15, wherein said fluid is selected from the group consisting of steam, nitrogen gas, carbon dioxide, methane, ethane, ethylene, propane, propylene or butane.
20. A process according to claim 15, wherein said fiber-forming polymer is a poly-.alpha.-olefin.
21. A process according to claim 16, wherein said hydrophilic polymer is completely or partially saponified polyvinyl alcohol or a co-polymer thereof.
22. A process according to claim 15, wherein said solvent is sel-ected from the group consisting of hexane, methylene chloride, chloroform, pentane, heptane, benzene, methylethyl ketone, butane, pentene, cyclohexane or cyclopentane.
23. A process according to claim 15, wherein said aqueous dispersion medium is water.
24. A process according to claim 15, wherein the polymer concen-tration in a polymer solution phase consisting of said polymer and said solvent is about 5 - 70% by weight.
25. A process according to claim 15, wherein the ratio of a polymer solution phase consisting of said polymer and said solvent to said aqueous dispersion medium is equal to or less than about 10.
CA222,963A 1974-03-22 1975-03-24 Flowing fluid into nozzle in flash-spinning emulsion and forming pulp Expired CA1091412A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP3147874A JPS50123917A (en) 1974-03-22 1974-03-22
JP31478/74 1974-03-22
JP50007062A JPS5824524B2 (en) 1975-01-17 1975-01-17 Gosei Pulp Youbutsu
JP7062/75 1975-01-17

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CA1091412A true CA1091412A (en) 1980-12-16

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FR (1) FR2274731A1 (en)
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2430652A1 (en) * 1978-07-04 1980-02-01 Comp Generale Electricite Synthetic paper for electrical insulation in oil - comprises nonwoven thermoplastic fibre sheet coated with lower melting polymer
IT1151747B (en) * 1982-04-27 1986-12-24 Montedison Spa TWO-COMPONENT SYNTHETIC FIBERS SUITABLE TO REPLACE CELULOSIC FIBERS IN PAPER AND EXTRA-PAPER FIELDS, AND PROCEDURE FOR THEIR PREPARATION
GB2287482A (en) * 1994-02-28 1995-09-20 Hoechst Celanese Corp Synthetic paper pulp
US6638470B2 (en) 2000-02-15 2003-10-28 E. I. Du Pont De Nemours And Company Flash-spinning process and solution

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