DK146600B - METHOD OF FLASH SPINING POLYOLEIN FIBERS - Google Patents

Description

λ 146600 ο

The present invention relates to a method of flash-spinning polyolefin fibers, in which a mixture containing water, the polyolefin and an organic liquid capable of dissolving or swelling the polyolefin is prepared and flash-spun from an elevated pressure zone into a zone of lower pressure for evaporation of the organic liquid and precipitation of the polyolefin as fibers. These fibers are of suitable quality for making paper or similar nonwoven web material.

Various methods have previously been proposed for producing such fibers by flash-spinning a mixture of a synthetic fiber-forming polymer into a liquid which can be evaporated as the mixture is expanded through a nozzle at elevated pressure and into a zone of lower pressure. , since the temperature of the liquid before expansion is such that the liquid boils after expansion, ie. at least part of the liquid evaporates at the reduced pressure. Methods in which a solution of the polymer in a solvent is flash-spun to form fibers are described in U.S. Patent No. 3,081,519, British Patent No. 1,262,531, and German Patent Publication No. 19 58,609. in which molten polymer and water are flash-spun are disclosed in U.S. Patent No. 3,402,231 and French Patent No. 1,350,931.

In order to provide a fiber of better quality than obtained by the above methods, proposals have been made for flash-spinning an "emulsion" containing the polymer, a solvent for the polymer and water. Such proposals are made in British Patent Specification No. 1,323,174, German Publication Publication No. 2,144,409 and the specification for Danish Patent Application No. 4997/72. In these prior methods, in which an emulsion is flash-spun, the liquid which vaporizes contains water as its continuous phase, containing dispersed droplets of the solvent forming the disperse phase.

It is the object of the present invention to provide a process for producing polyolefin fibers which are better suited for use in papermaking to provide paper of superior quality.

2 146600

ISLAND

The process of the invention is characterized by flash-spinning a water-in-oil emulsion comprising the water dispersed in a continuous phase comprising the polyolefin and the organic liquid.

It has now been found that the fibers obtained by flash-spinning an emulsion of polymer are solvent. part and water, give better fibers when the solvent constitutes the continuous phase and water the disperse phase than when the reverse is the case, cf. the above technique, where the water is the continuous phase and the solvent is the dispersed phase.

An inverse or opposite emulsion (water-in-oil), in which water is the dispersed phase, is generally more difficult to form than the emulsions encountered in most cases in emulsion technology and which are oil-in-oil. water emulsions; but it has now been demonstrated that it is hereby possible to prepare and flash-spin water-in-oil emulsions containing polvolefins to provide fibers with very fine properties.

Surprisingly, it has been found that by making and flash-spinning a water-in-oil emulsion containing a polyolefin as a product, relatively finely divided single fibers are obtained rather than continuous fiber strands, ie. filaments.

Most prior methods show a tendency to deliver the products in the form of smooth filaments, which is undesirable when a fibrous product is contemplated to be used for the production of nonwoven web materials such as paper obtained by wet or drying a tangled mass which then binding.

By contrast, in the process of the invention, fibers of convenient quality for making paper or similar nonwoven web material are obtained directly by the flash spinning, the polymer precipitating in the form of fibers which can be relatively easily hydrated and formed in the form of paper webs 35 by conventional techniques.

Preferably, according to the invention, water-in-oil emulsion is obtained by dissolving the polyolefin in the solvent and dispersing the water in the solution.

For reasons not currently fully understood 3 146600

ISLAND

Furthermore, it has been found that fibers made by the process of the invention have superior properties compared to fibers made by flash spinning of a conventional oil-in-water emulsion, i.e. a comparative mixture in which the polymer solution in oil constitutes the disperse phase and water the continuous phase. This is found when the respective fibers are used in the manufacture of paper or non-woven web materials in general.

A detailed comparison of the properties is given below, but it can be briefly mentioned here that compared to fibers made by flash-spinning oil-in-water emulsion in the form of a comparative mixture in which water constitutes the continuous phase, the fibers made by the process According to the invention, a higher surface area, a higher drainage factor, higher strength values, thereby providing sheets of paper with generally superior properties which are not only surprising but extremely significant. Such fiber properties are essential for a sufficiently good pulp for papermaking. Higher surface area gives the fibers greater whiteness and clarity and better absorbent properties.

Improved strength properties, e.g. greater breaking strength, tear strength, resistance to contagion, etc. also make these fibers more competitive with the pulp types made from natural cellulose.

In addition, the process of the invention provides such improved fibers which also have a relatively low content of polymer thicknesses and fiber bundles. A low level of polymer thicknesses and fiber bundles 30 is of great importance for the use of the fibers for many paper grades, e.g. printing papers where the pressure of the roll during the papermaking causes these thickens and bundles to appear as transparent spots in the paper.

The polyolefins used in the process of the invention are thermoplastic and fiber forming, i.e. is capable of forming fibers by conventional spinning technique.

146600 -, 4

ISLAND

Crystalline or partially crystalline polyolefins such as low pressure polyethylene (Ziegler-Natta), isotactic or partially isotactic polypropylene and ethylene-propylene copolymers are used. Polybutenes and polymethyl pentenes 5 are further examples of polyvolefins which can be used in the process of the invention.

The preferably used polyolefins are polyethylene or polypropylene having an intrinsic viscosity number (as determined by measuring specific viscosity of diluted solutions in decalin at 135 ° C and extrapolating to zero concentration) of about 0.7 dl / g, which for polyethylene corresponds to an average molecular weight of more than approx. 30,000 to 40,000.

The polyolefins used in the process of the invention may be in the form of dried powder or as pellets or preferably as wet cake, slurry or solution of polyolefin in the reaction solvent as obtained after polymerization.

. Normally, in the process of the invention, any substituted or unsubstituted aliphatic, aromatic or cyclic hydrocarbon which is a solvent for the polyolefin at elevated temperatures and pressures which are relatively inert under the operating conditions can be used as the organic liquid. preferably has a boiling point at atmospheric pressure which is less than the softening point of the polyolefin and which is practically immiscible with water or forms a polyolefin solution which is practically immiscible with water. The solvent may be liquid or gaseous at room temperature and atmospheric pressure. It is preferred that it is a liquid at standard pressure, as otherwise the system must be pressurized after the flash spinning zone. Illustrative of the solvents which may be used are aromatic hydrocarbons (e.g. benzene and toluene), aliphatic hydrocarbons (e.g., butane, pentane, hexane, heptane, octane and their isomers and homologs), alicyclic hydrocarbons (cyclohexane), chlorinated hydrocarbons (e.g., methylene chloride, carbon tetrachloride, chloroform, ethylene chloride and methyl chloride) higher alcohols, esters, ethers, ketones, nitriles, amides, fluorinated compounds (e.g., fluorocarbons and nitromethane) and mixtures of the above-mentioned solvents or other solvents.

The polyolefin-solvent-water mixture can be formed according to the concentration of water by various methods. One can start with a solution of the polyolefin in the solvent as it comes from the solution polymerization process, either at the same concentration of polyolefin in solvent, diluted or concentrated, then water is added to the solution or vice versa. Generally, hot water is used in such a process to prevent the precipitation of the polyolefin. Alternatively, one may begin with a slurry of polyolefin particles in the solvent as produced by a slurry polymerization process, and a suitable amount of water is then added to the slurry or vice versa. A further alternative method would be to start with a dry polyolefin powder or granules or a wet cake, as may be obtained at some steps after solvent removal in the polymerization plant, where the proper amounts of solvent and water are mixed or mixed with the dry powder in any row-25 follow.

As explained below, it is advantageous for the solvent to be present before addition of water, as adding water to the solvent and not vice versa will help to ensure that the solvent or polyolefin solution will form the continuous phase of the mixture which must be produced. The latter problem is important when using an amount of water that is close to the limit of inversion, ie. close to the point where the amount of water is the amount that will constitute the continuous phase. When the amount of water is substantially below the boundary where an inversion occurs, especially below 30% by volume of the mixture, any suitable mixing method or order of addition can be used for the materials.

The polyolefin concentration relative to the solvent is not critical as the solvent is present in an amount greater than 100% by weight of the polyolefin and sufficient to give a viscosity at the solution temperature used so that the polyolefin solution will be easy to handle, i.e. a viscosity of less than approx. 500 poise. Generally, the polyolefin concentration will range from about 10 to about 2 to approx. 30% by weight of the solvent plus polyolefin and preferably are in the range of from approx. 5% to approx. 15%.

One of the functions of the water is to reduce the temperature of the fibrous mass in the zone which follows immediately after the nozzle. The addition of water increases the total vapor pressure of the system and thus reduces its boiling point. However, it will be convenient to use water in an amount of at least approx. And preferably above about 1%. 10% by volume of the solvent-water mixture. Thus, by lowering the boiling point of the mixture, the temperature of the fibrous pulp formed after evaporation is reduced by flash spinning and the properties of the resulting fibers are improved for papermaking purposes.

Another function of the water is to act as a carrier for a hydrophilic water dispersant for the fibers to be formed. It has been found that it is most advantageous for the water dispersant to be present during flash spinning and precipitation of the fibrous polymer. However, although the presence of the water dispersant on the fibers produced by this method is advantageous, the best of such agents are those which one would expect to be undesirable for a water-in-oil emulsion. Nevertheless, the presence of hydrophilic water dispersants in the mixture is preferred before flash spinning. An equivalent amount of the same agent added at a later stage to the fibers already formed does not give the fibers the same degree of suitability to be refined. Therefore, the water should be present in a sufficient amount to carry or cause the amount of the hydrophilic agent used to impart to the fibrous polyolefin the desired level of water perviousness, preferably as a solution thereof. Extra straw water over such a minimum amount required to carry or carry the agent can be used to impart an appropriate viscosity to the aqueous solvent or dispersion agent, i.e. that the aqueous solution of the water dispersant must not be so viscous that it presents problems with handling or incorporation into the polyolefin solution as a dispersing phase. Furthermore, the water can help by reducing the viscosity of the mixture to a level below the viscosity value of the polyolefin solution alone, thus allowing the use of higher polyolefin concentrations. Usually, the viscosity of the aqueous solution and / or mixture should be less than about 10

500 poise at the temperature used.

A further function of the water is to provide energy (enthalpy) to assist in the evaporation of the solvent during flash spinning, as it is not desirable to raise the temperature as high as would otherwise be necessary to bring the solvent to to completely evaporate where this occurs alone.

However, the amount of water must not be so large as to require excessively high amounts of heat to reach the desired flash spinning temperature, ie. in addition, once the amount of water which gives one suitable viscosity is determined, in addition, to a certain extent only extra water can be used to aid in lowering the viscosity of the mixture and to promote solvent evaporation; but the extra amount of water may not be quite large.

The amount of water required to perform the preceding functions is always less than the amount at which an inversion occurs, ie. where the water must become the continuous phase of the mixture. A necessary condition for ensuring that the organic liquid or solution constitutes the continuous phase is that the proportion of water in the mixture is quite low. If the proportion of water is more than approx. 70%, it is very difficult to form a water-in-oil emulsion, even if you try. Even at somewhat lower proportions of water, e.g. above 60% water, any usual or normal mixing method will be prone to produce an oil-in-water emulsion. As the proportion of water decreases, it becomes easier to form a water-in-oil emulsion. In mixtures where water will tend to be more stable as the continuous phase, it is desirable to use special mixing techniques to establish the water as the least stable discontinuous phase. Suitable techniques of this kind are known to those skilled in the art of emulsion. described in Volume 8 of Kirk-Othmer1's "Encyclopaedia of Chemical Technology", 15 second revised edition.

A preferred method of securing a water-in-oil emulsion, when the proportion of water sufficient for either water or the organic liquid to be the continuous phase, is to add the water to the liquid at a slow rate. sufficiently slow that even at the point of addition there is no local excess of water relative to organic liquid and emulsion already formed while the mixture is stirred or vigorously so that the water breaks up into drops as it is added. One can ensure that the water addition is sufficiently gradual by measuring the electrical conductivity of the organic liquid and then monitoring and controlling the conductivity to ensure that the rate of addition under given conditions of agitation is such that the conductivity remains less than twice the conductivity at the beginning.

As a useful guideline, it is desirable to use such special mixing technique where the water should be approx. 30% or more of the mixture. Specifically, when the amount of water used is approx. 30% or more, it is desirable to first form a solution of the polyolefin and solvent and then to add 146600 µm.

ISLAND

add water to this solution with vigorous stirring. In this regard, the term "polyolefin solution" is understood herein to mean the swollen or dissolved mixture resulting from the solvent's admixture with the polyvinyl fin, usually at elevated temperature. It is further desirable that the entire mixture mass be continuously subjected to such agitation, both during and after water addition. The mixing vessel or apparatus may be designed to impart such uniform and vigorous agitation, e.g. by appropriate design of the vessel, mounting of baffle plates and implementation of special stirring technique.

In this way, areas with very low agitation can be avoided which could possibly induce phase inversion.

It is preferable to carry out this mixing process while both the water and the polyolefin solution are relatively hot. Desirably, the polyolefin solution should be at a temperature above the melt solution temperature and the water to be added should be at a sufficiently high temperature for the mixture 20 to remain above such a melt solution temperature during and after the water addition. This approach will help prevent phase inversion during water addition.

If the aqueous and polyolefin solution phases are allowed to separate during or after the addition of water, phase inversion may occur. It is therefore desirable to add the water at a rate so that phase separation will be avoided and to maintain vigorous agitation during and after water addition, also for the same purpose. Thus, as previously mentioned, the water is preferably added gradually at such a rate that it is rapidly mixed uniformly in the polyolefin solution. That is, the water should not be added faster than dispersed as droplets in the continuous polyolefin solvent-35 phase.

When the mixture contains approx. 30% water or less, preferably a water-in-oil emulsion is formed and it is not even necessary to add the water to the organic liquids. At low water concentrations, the two liquids can even be mixed and then stirred, or the solution (or a slurry of polyolefin particles in organic liquid) added to the water.

Thus, in Examples 1 to 6 below, where the water concentration is only 16%, no special mixing method is followed. By contrast, in Experiment # 1 of Example 7, where the water concentration is 40%, the water is gradually added to the solution. In fact, water concentrations of the order of 40 to 50% are preferred to the process of the invention, although more care must be taken to ensure that the water is the discontinuous phase.

In a continuous flash spinning operation, as a portion of the mixture thus formed is flash spun through a nozzle, additional or additional amounts of polyolefin solution and water may be continuously added, with stirring, to the remaining mixture in the proper ratio as discussed above, so that It is still kept as the discontinuous phase of the flash-spinning mixture.

One of the important features of the present invention is that it has been found that it is not necessary to form a stable "emulsion", thereby eliminating the need to use emulsifiers. However, certain surfactants can also be used in the mixture, namely to promote the water dispersibility of the flash-spun fibrous polyolefin formed. These agents are preferably water-soluble or partially water-soluble high molecular weight materials. However, they may also be materials which are soluble or partially soluble in the solutions of the agent. Some of these agents may technically be classified as "emulsifiers"; but they are used only in a sufficient quantity to impart to the final fibrous product the requisite degree of dispersibility in water, namely for its subsequent use for papermaking purposes, and not in the amounts usually required to form a stable emulsion, i.e. on the step before flash spinning. Since the water dispersants must in fact be hydrophilic to a certain extent, they are not of the type which would normally be used to produce a water-in-oil emulsion, i.e. one would normally use a hydrophobic (lipophilic) emulsifier with relatively low HLB (hydrophilic-lipophilic balance) to form a water-in-oil emulsion. The amount of water dispersant used can be in the range of approx. 0.1 to approx. 15% by weight 10 of the polyolefin and preferably ranges from 0.1 to approx. 5% by weight. The preferred water dispersant is a polyvinyl alcohol having a degree of hydrolysis of more than ca. 77% and preferably above approx. 85% and with a viscosity (measured in a 4% aqueous solution at 20 ° C) of more than approx. 2 centipoise. The polyvinyl alcohol is preferably added together with the water at the time the mixture is formed. Illustrative of other water dispersants which may be used for this purpose are cationic guar, cationic starch, cardiac sludge starch, methyl cellulose, and "Lytron 820" (a styrene-maleine copolymer).

The ingredients of the mixture can be placed in any suitable container which can be heated to elevated temperature and kept under pressure therewith. Usually an autoclave is used. It is important, however, that the container used be provided with a mixing or stirring means capable of keeping the mixture in a constantly stirred state, since a stable emulsion is not formed and as the mixture, upon standing, will quickly separate into the mixture. two distinct, distinct phases.

The ingredients are then heated to appropriate temperature and stirred to form a mixture in which water is present as a continuous or dispersed phase in a continuous phase of polyolefin solution. The temperature used is preferably above the melt-solution temperature 35 of the polyolefin in the solvent used. The melt-solution temperature of any particular polyolefin in a solvent is determined by placing low concentrations of the polyolefin (e.g., 0.1 and 1.0% by weight) in the solvent in test tubes, which are then sealed and placed in an oil bath. The oil bath temperature is raised slowly (for example, at 10 ° C per hour) until the last 5 traces of polyolefin disappear. This temperature is the melt solution temperature. In some cases, it may be desirable to operate at a temperature below the melt solution temperature, in which case the polyolefin should be present at least in the swollen state.

The maximum temperature used must be less than the critical temperature of the solvent and / or the decomposition temperature of the polyolefin. However, it is preferred to use somewhat lower temperature. For polyethylene and polypropylene, it is preferred to operate between approx.

15 120 ° C and approx. 180 ° C and preferably between ca. 130 ° C and approx. 160 ° C.

The pressure used in the container containing the heated mixture is preferably practically autogenous.

Pressure substantially higher than autogenous pressure is not required and may even cause poor fiber formation for some nozzle designs. It may be desirable to use an inert gas such as nitrogen during the flash spinning operation to keep the mixture speed through the nozzle at a fairly constant level.

Flash spinning is preferably carried out through a nozzle (which by definition has its largest longitudinal dimension) rather than a sharp-edged opening (which by definition has no longitudinal dimension) because it has been found to be highly desirable to communicate the mixture ( and especially its polyolefi component) shear force action immediately prior to flash spinning. One such shear force effect helps in fiber formation and improves the fiber properties for papermaking purposes. The nozzle may be of circular or non-circular cross-section and may optionally be a circular ring.

The flash spinning is performed by passing the mixture of polyolefin solvent and water through the nozzle into a zone of lower pressure. Preferably, the pressure in this lower pressure zone 1 is substantially atmospheric pressure or below, since the higher the temperature of the fibrous product after formation, the higher the pressure. Generally, before the flash is spun 5 to the lower pressure zone, the pressure on the emulsion should be below approx. 3.5 ato and preferably below about 1.0 ato.

Flash spinning is practically adiabatic, but may vary slightly.

During flash spinning, the polyolefin is precipitated as a fibrous "nodule" which is a loose cluster of fibers, of which only a few are continuous.

In a preferred embodiment of the present invention, low pressure water vapor (below 1.4 ato) is added to the fibrous nodule after the flash spinning zone 15 to expel the remaining solvent from the fibrous nodule. This can be carried out in a tank or preferably in a conduit immediately after the nozzle.

The free-breaking nodule is collected in an appropriate receiving vessel, preferably a container which allows the evaporated solvent to be separated therefrom.

In commercial operation, the fibrous nodule is diluted with water to an appropriate consistency of less than approx. 5% and preferably less than about 5%. 2% by weight and then passed on as an aqueous slurry through a slice hydrafine to bring the fibers into a form which is optimally suitable for papermaking. In the hydrefining, the fibrous nodule is separated into separate fibers, and this treatment can also be used to control the fiber lengths. Generally, it is desirable to make multiple passes through the hydrafiner. However, disc hydrefining of the fibrous nodule is not essential.

The fibers can, after hydrefining, be diluted to the appropriate consistency and further processed into synthetic paper webs, either alone or admixed with cellulose fibers for normal papermaking. Alternatively, the fibers can be dewatered, pressed into bales, stored and shipped to final consumers.

14 146600 o

However, although the above description illustrates a portion process by which the mixture of polyolefin, solvent and water is prepared in a suitable container, it is also possible to prepare the mixture on a continuous basis by mixing the polyolefin solution with superheated water with continuous operation in an the production line inserted mixing means immediately before flash spinning through the nozzle.

A determination of whether the water is present as a discontinuous phase or as a continuous phase can be made as follows. The mixture is formed at the appropriate temperature and pressure and with the degree of stirring that would normally be used. Electrodes consisting of two conductive metals separated at a distance of 12-13 mm or more are immersed in the liquid mixture. The electrodes are connected to the two poles of a battery, and the generated signal is recorded on a typewriter connected in series with the electrodes.

The signal produced is directly proportional to the conductivity of the mixture. A trace amount of an ionizable material such as sodium chloride can be used in the water to enhance its conductivity. Where the water constitutes the discontinuous phase, a very low conductivity reading or a reading or transcript of a conductivity of 0, i.e. about the same conductivity as the polyvinyl solvent phase of the mixture.

Thus, it can be seen that in forming the desired mixture with water as the discontinuous phase, the rate of stirring of the mixture is desirably high enough to maintain the conductivity of the mixture at about the same value as the conductivity of the polyolefin solution phase.

Likewise, in preparing such mixtures where the water concentration is desirably so high that a system of water such as the continuous phase is favored, the water must be added to the polyolefin solution at a sufficient gradual rate to maintain the conductivity of the mixture at about the level or value of the conductivity of the polyolefin solution phase.

ISLAND

146600 15

Other suitable methods for determining whether an oil-in-water or a water-in-oil type emulsion is obtained are described on pages 146 and 147 of Volume 8 of Kirk-Othmer "Encyclopendia and Chemical Technoloby" , Second 5 Revised Edition 1965.

The following examples serve to illustrate the method of the invention.

Example 1 10 In the present example, a solution boiler is used in the form of a glass-lined 3000 liter tank fitted with baffle plates and with a centrally placed 7.5 horsepower stirrer mounted on 2 turbine type four blade agitator assemblies. The lower turbine measures 68.5 cm from tip to tip, and the upper turbine measures 48.3 cm from tip to tip. The stirrer runs throughout the experiment. 227 l of water containing 1% by weight of polyvinyl alcohol ("Monsanto Gel-vatol" ® viscosity 4-6 centipoise and 87.7-89% hydrolyzed), based on the weight of the polyethylene to be used, 20 is added to the tank, then 45 is added. 4 kg of high density polyethylene with a limit viscosity of 1.4 dl / g and a melt index of 5.5 ("Mitsui® 2200 P"). The container is closed tightly and 1140 liters of n-he-xane are introduced. The volume ratio of water to hexane in the mixture is 25 as 1: 5 and the polyethylene concentration is 40 g per liter. liter of hexane. The contents of the container are then heated and the mixture is introduced through a 7.6 cm line, which after 13 cm bends into a waterproof angular type control valve with an opening with a diameter of 9.5 mm and a length of 7 mm. A nipple-shaped plug in the valve opening together with the wall of the opening forms a circular ring. The valve is approx. a quarter open when in operation. The mixture flows through the circular ring forming the flash spinning nozzle at a rate of 180 g of polyethylene per minute. minute. The mixture is flash-spun into a 2.5 cm internal diameter conduit. At a distance of approx. 15.3 cm after the nozzle, low pressure water vapor (0.7 ato) is introduced into this 2.5 mm conduit to evaporate the amount of solvent remaining in the fibrous nodule after flash spinning. At a distance of approx. 5.5 m from the nozzle, the conduit expands and enters a steam separation stove where the vapors are removed from the top of the chamber. Hot dilution water of 85 ° C is introduced into the top of the vapor separation chamber at a rate of approx. 19 liters per minute. The water and the fibrous nodule fall to the bottom of the vapor separation chamber and are fed at a temperature of 80-90 ° C and with a consistency of approx. 1% for a Jones double disc hydrafiner (with disc diameter 30.5 cm) 10 provided with brush type plates (Jones type 1, 1, 1.5 + 10 °). The slices are operated at 2117 rpm. per minute and a clearance of 0.10 mm - 0.10 mm. The fibers are subjected to a total of four passages through the hydrafiner, with passages 2 through 4 being made at a storage temperature of 40 to 50 ° C.

(R) An additional weight percent of "Gelvatol" ^ 20-30 polyvinyl alcohol (based on the weight of polyethylene) is added to the storage tank, and the stock is given from the tank a fifth passage through the hydrafiner, the plates now being set to a clearance of 0.25 - 0.10 mm. The polyethylene fibers have the following fiber distribution tested according to TAPPI standard T 233 su 64:

Table 1A

Back to screen 25 (Mesh US standard) Weight percent 20 10.3 35 33.8 65 23.8 150 17.4 30 270 5.0 through 270 9.7

The fibers have a drainage factor of 0.24 second / gram.

A portion of the resulting fibers are handmade into sheets according to TAPPI standard T-205-m-58 with a modified wet pressing (28 atm) and a heat sizing step (121 ° C at minimum pressure). Another portion of the fibers are mixed in ratio 50/50 by weight with bleached electric power Dulp, which has a 3 Canadian standard freedom of 410 cm, and is hand-made into sheets by the same method. The resulting handmade sheets are tested with the following result:

Table IB

Feature 100% 50% blend o

Base weight, g / m 61.2 61.2 3 10 Density g / m 0.36 0.48

Translucency,% 83.4 78.9

Clarity,% (Elrepho No. 8) 88.9 84.4

Break length m * 139 2416 TEA, kg-cm / cm 0.06 34.3 15 Inner connection, Scott units 14 90

Tear strength g / sheet 6 28 2fe The length of a web that just cannot support itself TEA = Pull energy absorption (= toughness) 20 Another portion of the polyethylene fibers is mixed with a bleached electric power pulp that has a standard Canadian freedom of 410 cm to obtain a pulp containing 40% by weight of polyethylene fibers and 60% by weight of kraft fibers. The resulting mixture is hydrated on Jor 25 Dance Hydrafins to provide a paper mass slurry with a Canadian standard 250 cm freedom and processed into paper on a paper machine operated under two levels of heat sizing ( 107 ° C and 135 ° C in the paper web). The resulting paper webs have 30 properties:

ISLAND

18 146600

Table 1C

Properties Heat bonding temperature

107 ° C 135 ° C

Base weight, g / m 66.6 63.3

Difficulty, mm 0.132 0.11

Density, g / cm 2 0.504 0.573. , MD 23 24

Tear strength g / sheet XD 26 27

Tensile breaking strength, kg / 15 mm Xø l'll 1 ^ 70 ro Break elongation,% Mg TEA, kg-cm / cm2 8f8ϋ 8, '852

Fold (MIT)] φ 1 I

Stiffness, g / cm (Loss) 0 0.96

Scott's inner context 152 285 2 —3 15 kg-cm / cm x 10 3

Smoothness, cm / min. WS 328 327 (Sheffield) FS 352 293 3

Porosity cm / min. (Sheffield) 249 278

Oil absorption,% 45 32 20 Sugar color, sec. 9 2'c FS 0 1.6

Clarity,% (Elrepho # 8) 85.4 80.9

Translucency,% 80.4 69.1. Light scattering coefficient 408 253

Fracture length, m MD 2931 3271 25 XD 1492 1786 WS = Vireside MD = machine direction FS = felt side XD = cross machine direction 30 In the above and following examples, the paper weight of the samples, gravity (ie thickness), tear, folding and density of the handmade is determined. sheets by methods according to TAPPI standard T-411, tear strength according to TAPPI standard T-410, gravity according to TAPPI standard T-411, tear strength 35 according to TAPPI standard T-140, folding according to TAPPI standard T-511 and density according to TAPPI standard 426. - the break elongation, the TEA (wood energy absorption, which is an o 148600 measure for paper toughness) and the fracture length for both handmade sheets and paper webs made by machine by methods according to TAPPI standard T-494. The stiffness of both types of paper sheets is determined according to TAPPI standard T-489-70. The clarity (Elrepho 5 # 8) is determined for both types of sheet according to TAPPI standard T.525. Smoothness is determined for both types according to TAPPI Routine Control Method No. 285. Oil absorption is determined for both types of sheets according to TAPPI Routine Control Method No. 26 (1966). The transparency and light scattering coefficient 10 are determined for both types of sheets according to TAPPI standard T.425.

Other tests are indicated by the machine used for conducting the tests, which is otherwise well known to those skilled in the paper industry. The drainage factor which is closely related to the hydrodynamic surface area of the fibers and is more closely related to the drainage properties of the fibers to be used in papermaking than the gas adsorbing surface area is determined essentially according to TAPPI sample T-221 OS-63 with a slight modification in calculation method. In short, this provision assumes that approx.

Weigh 10 grams of a fiber sample and disperse in water.

Then, the slurry is added to a standard sheet form and water is added until the contents reach the mark. The slurry is stirred at four up and down strokes with a standard stirrer which is then removed. The water temperature in fore-25 but is measured and the drain valve opens. The time between the valve opening and the first suction sound is recorded. The process is repeated with water alone (ie without filter) in the sheet form and the temperature and drainage time are recorded. The drainage factor expressed in seconds per grams are then calculated as follows: 30 ID + 0.3 (i - 1) (D - 4)] - [d + 0.3 (i - 1) (d - 4)] DF = _VT__T_

W

where DF denotes the drainage factor in seconds / gram, 35 D denotes the drainage time with pulp in the mold expressed in seconds, d denotes the drainage time without pulp in the mold expressed in seconds,

ISLAND

where V "T represents the viscosity of water at temperature T, and W represents the weight of the fibers used in the sample, expressed in grams.

The amount of djp-1) is taken from a table in the above-mentioned TAPPI 5 sample T-221 OS-63. This amount is multiplied by 0.3, which is an empirically determined factor for the fibers in question.

Example 2 The procedure of Example 1 is repeated with the following exceptions: a) the polyethylene concentration is 80 grams / liter; b) the mixture passes through the nozzle at a rate of 250 grams per liter. c) The hydration conditions are as follows: 1) The first passage is made at 80-90 ° C with a plate light of 0.10 mm, 2) The second to the sixth passage is made at a temperature of 40 to 50 ° C with a plate illumination of 0.10 mm.

No extra polyvinyl alcohol is added.

The resulting fibers have the following fiber distribution:

Table 2A

Back to Sieve (Mesh US standard) Weight percent 20 6.4 35 33.5 30 65 29.2 150 17.4 270 6.3 through 270 7.2 35 The fiber drainage factor is 0.46 second / gram.

ISLAND

146600 21

Handmade sheets are made as in Example 1, namely, one group contains 100% polyethylene fibers and the other group is made from a 50/50 blend of the polyethylene fibers with bleached electric power fibers as described in Example 1. The properties are as follows:

Table 2B

Feature 100% 50% blend 2 10 Base weight, g / m 65.5 63.4

Density g / m2 0.36 0.44

Translucency,% 90.3 84.7

Clarity,% (Elrepho # 8) 92.2 86.0

Break length m * 145 2036 15 TEA, kg-cm / cm2 ** 0.06 29.8

Internal context, Scotte units 25 82

Tear strength g / sheet 3 30 £ The length of a web that just cannot support itself 20 TEA = Draw energy absorption (= toughness)

A portion of the fibers are blended with the bleached electric power fibers as described in Example 1 (40% by weight polyethylene fibers and 60% by weight of power fibers) and made into a 25 paper web on a paper machine at 2 levels for heat sizing as in Example 1. The The paper web thus produced has the following characteristics:

ISLAND

146600 22

Table 2C

Properties Heat bonding temperature

107 ° C 135 ° C

Base weight, g / m2 66.6 63.3 5 Room, mm 0.132 0.11

Density, g / cm3 0.504 0.573

Tear strength g / sheet MD 23 24 XD 26 27

Tensile strength, kg / 15 mm MD 2.93 3.11 10 XD 1.49 1.70

Fracture elongation,% MD 1.6 1.7 XD 3.5 3.8 TEA, kg-cm / cm2 MD 0.019 0.020 XD 0.025 0.032 15 Fold (MIT) MD 3 7 XD 2 3

Stiffness, g / cm (Loss) MD 1/17 0.96 XD 0.46 0.45

Scott's internal composition 20 kg-cm / cm2 x 10 ΙΟ-3 152 285

Smoothness, cm3 / min WS 328 327 (Sheffield) FS 353 293

Porosity cm3 / m (Sheffield) 249 278

Oil absorption,% 45 32 25 Sugar color, sec. WS 0 2.1 FS 0 1.6

Clarity,% (Elrepho # 8) 85.4 80.9

Translucency,% 80.4 69.1

Break length, m MD 3155 3714 30 XD 1553 1900

Example 3

The procedure of Example 1 is repeated with the following exceptions: a) The polyethylene concentration is 80 grams / liter b) The mixture is passed through the nozzle at 150 grams per liter. minute, and

ISLAND

C) the hydration conditions are as follows: 1) The first passage is made at 80-90 ° C with a plate illumination of 0.05 + 0.10 mm, 2) The second and even the sixth passage 5 are made at 20 ° C with a plate illumination of 0.05 + 0.10 mm. No extra polyvinyl alcohol is added.

The resulting fibers have the following fiber distribution: 10

Table 3A

Back to view (Mesh US standard) Weight percent 20 2.3 15 35 21.2 65 32.7 150 26.2 270 9.0 through 270 8.6 20

The fiber drainage factor is 1.10 sec / gram.

Handmade sheets are made as in Example 1, one group containing 100% polyethylene fibers and the other group being prepared from a 50/50 blend of these 25 fibers with the bleached electric power described in Example 1. The handmade sheets thus produced have the following characteristics:

Table 3B

Property 100% 50% mixture 2 30 Base weight, g / m 62.2 62.3 3

Density, g / cm 0.41 0.50

Translucency,% 93.7 88.2

Clarity,% (Elrepho # 8) 93.7 88.4

Break length, m * 305 2534 35 TEA, kg-cm / cm ** 2.4 47.6

Internal context, Scotte units 20 82

Tear strength g / sheet 5 29 * The length of a web that just cannot support itself ** TEA = Draw energy absorption (= toughness).

ISLAND

146600 24

A portion of the fibers are blended with the bleached electrical power described in Example 1 (40% by weight polyethylene fibers and 60% by weight) and processed into a paper web on a paper machine at two heat sealing levels as in Example 1. The web thus prepared has the following properties:

Table 30

Properties Heat bonding temperature

10 ° C 135 ° C

Base weight, g / m2 60.3 59.9

Difficulty, mm 0.130 0.118

Density, g / cm 2 0.46l 0.504

Tear strength g / sheet MD yi yi 15 XD 35 36

Tensile breaking strength MD 2.85 3.65 XD 1.39 1.80

Fracture elongation, <fa MD 1.6 1.7 XD 3.8 3.5 20 TEA, kg-cm / cm2 MD 0.019 0.025 XD 0.027 0.034

Folding (MIT) MD 5 12 XD 2 7

Stiffness, g / em (Loser) MD 1.2 1.1 XD 0.51 0.5β

Seott's inner composition kg-cm / cm2 x 10 ^ 147 A66

Smoothness, cnrVmin WS 329 363 (Sheffield) FS 325 346 3Q Porosity cm 2 / min (Sheffield) 265 400

Oil absorption,% 53 35

Sugar color, sec. WS 0 14.6 PS 0 16.9

Clarity,% (Elrepho # 8) 87.4 79.5 35 Translucency,% 85.9 65.4

Break length, mm MD 3152 4o68 XD 1543 2108 WS = Wire side MD = machine direction FS = Felt side XD = cross in machine direction

ISLAND

146600 25

Example 4 In the present example, the container to be flash-spun in the blend used is a "Benco" model 575, 3.8 liter reactor equipped with 10.5 5 atm water vapor sheath, nitrogen supply and discharge and a centrally located air-driven agitator shaft fitted with tight mechanical closure. A 10 cm diameter turbine stirrer with six pitched blades (from Bench Scale Equipment Co.) is placed on the shaft 13 cm above the bottom of the container 10, and a baffle plate to produce strong shear force is placed approx. 9 cm below the turbine. In addition, the container is equipped with four internal vertical plates located at the same distance. The container is equipped with an electrode consisting of a piece of metal wire passed through a seal at one end of a short length of glass tube. The other end of the wire is pushed through a 30 cm long stainless steel tube (6.3 mm outer diameter) and the glass tube and the metal tube are joined by a "Swage" latch. The electrode is disposed in the container such that the wire is 20 above the level of the water in the mixture as described below. The wire is connected to one end of an ohmmeter placed in series with the battery. The stainless steel sleeve, which is separated from the wire by insulation throughout its length, having a distance or clearance between them of approx.

25 ice mm, is connected to the second pole of the battery. It was determined that the signal when measured on saline alone is approx.

140 millivolts, while the signal measured on n-hexane alone is approx.

0-1.0 millivolts. Starting from the bottom of the chamber, there is a 3/4 inch pipe with a ball valve located therein, which is 30 approx. 5 cm below the bottom of the chamber. Adjacent immediately to the ball valve is a nozzle. The nozzle consists of a brass plug with a length of 104 mm and a central hole disposed therein, namely a diameter of 3.5 mm in diameter. The nozzle plug is inserted into the 3/4 inch tube, continuing for a distance of approx. 30 cm past the nozzle and protrude into the atmosphere. The container or chamber is filled with 500 ml of water, 2500 ml of n-hexane, 100 g of polyethylene ("Mitsui® 220OP" as described in

ISLAND

Example 1), 2 grams of Gelvatol® 20-30 polyvinyl alcohol and 20 drops of a 25% aqueous sodium chloride solution.

The container is closed tightly, rinsed with nitrogen and heated to produce a temperature of between 5 145 and 150 ° C in its contents, the stirrer being operated at 650 rpm. minute. The contents of the container are kept at 145-150 ° C for approx. 1.5 hours to ensure complete dissolution of the polyolefin. The conductivity of the mixture is between 0.4 and 1.2 millivolts, which shows that the water is the discontinuous phase. The ball valve is then opened and the mixture passes through the nozzle while the pressure is kept constant in the vessel by supply of nitrogen. The fibrous product is collected by the discharge jet striking a wire screen. The fibers are hydrated by sending them at room temperature through a 30-cm Sprout Waldron single-disc hydrant (Sprout Waldron's pattern C-29-78-B), operated at 2800 rpm. per minute with a plate lighting of 0.5 mm, with a total of 4 passages.

The resulting fibers are distributed with the following fines:

Table 4Λ

Back to view (US standard) Weight percent 25 20 2.2 35 18.8 65 35.3 150 24.6 270 9.5 30 through 270 9.6

The fiber drainage factor is 4.3 seconds / gram.

Handmade sheets are made as in Example 1, one group containing 100% polyethylene fibers and the other being prepared from a 50/50 blend with the bleached electric power fibers described in Example 1. These handmade sheets have the following characteristics:

ISLAND

146600 27

Table 4B

Feature 100% 50/50 blend 2

Base weight, g / m 58.6 63.3

Density, g / cm 2 0.35 0.55 Transparency,% 95.3 89.5

Clarity,% (Elrepho # 8) 95.3 88.4

Break length, m * 0.009 0.06 TEA, kg-cm / cm2 ** 76.7 271.0

Internal context, Scott units 8.8 29.6 10 Tear strength g / sheet 0.54 3.4

Break elongation 3.4 3.7 The length of a trajectory that just cannot bear itself TEA = Draw energy absorption (= toughness).

15

Example 5

Example 4 is repeated except that polyvinyl alcohol is omitted from the mixture. The conductivity of the mixture is the same as in Example 4. The stirring is stopped briefly 20 to control the electrode and the conductivity rapidly increases to approx. 100 millivolts, thus demonstrating phase separation. After resuming stirring, the conductivity rapidly drops to 0.4-1.2 millivolts. The mixture is kept at 140 ° C for half an hour and then passed through the nozzle under a constant pressure of 11.6 atm. The fibers cannot be hydrated or made into handmade sheets as produced until they are treated with 1% by weight, based on the weight of the fibers, "Gelvatol" ® 20-30 polyvinyl alcohol, which is thus mixed in aqueous slurry. Following the treatment, the fibers are hydrated as in Example 4 and then have the following fiber distribution:

Table 5A

Back to goal (PS Standard) Weight percent 20 0.8 5 35 11.7 65 34.1 150 31.4 270 14.0 through 270 8.0 10

The fibers have a drainage factor of 16.5 seconds / gram.

Handmade sheets are made by the method of Example 1, one being made from 100% polyethylene fibers and the other from a 50/50 blended bleached electric blend as described in Example 1. These handmade sheets have the following properties:

Table 5B

20 Feature 100% 50/50 Mixture

Difficulty, mm 0.137 0.104 2

Base weight, g / m 53.6 52.1

Density, g / cm 2 0.43 0.57

Translucency,% 94.8 80.4 25 Clarity,% (Elrepho # 8) 94.3 89.0 TEA, kg-m / m2 2.76 4.45

Internal context, Scotte units 60 102

Tear strength g / sheet 16.0 33.0

Tensile strength kg / cm 0.565 1.91 30 Fracture elongation,% 6.0 3.4

Break length, m 955 3255

Example 6

The procedure of Example 4 is repeated using polypropylene having an intrinsic viscosity of 1.7 dl / g ("Hercules Profax® 6301"). In one experiment, the mixture contains 500 ml of water, 2500 ml of n-hexane, 200 146600 of 29 ° (5) grams of polypropylene and 2 grams of "Gelvatol", vy20-30 polyvinyl alcohol. This mixture is heated and maintained at 140 ° C for 1 hour. A second test identical to the first test is performed except that the polypropylene is used in an amount of 100 grams, and a third test identical to the second test except that raise the temperature of the mixture to 175-180 ° C before flash spinning, in all cases a fibrous product is obtained.

10

Example 7 and Comparative Example

Two experiments are carried out to compare fibrous products made according to the invention (experiment # 1) with the fibrous products prepared under equivalent fiber preparation conditions, but using a flash spinning mixture in which the water forms the continuous phase (experiment # 2 ).

In both of these experiments, a 10 liter container fitted with a vapor jacket and nitrogen supply and outlet, an conductivity measuring electrode and a centrally located vertical agitator shaft with mechanical seal closure are used.

A turbine with a diameter of 10 cm and an upwardly sloping blade inclination is placed on the shaft 5 cm from the bottom of the chamber. Two straight-blade baffles with a diameter of 10 cm are placed on the shaft 25 15 cm and 25 cm above the bottom of the boiler, respectively. A down-pumping turbine of 10 cm in diameter and a down-pumping turbine of 7.6 cm in diameter are placed on the shaft 35 cm and 45 cm above the bottom of the chamber, respectively. Three vertical baffles are placed inside on the wall of the container with equal radius 30 distances.

This construction ensures that the entire mixture is agitated and avoids areas of poor stirring that would otherwise promote the establishment of a continuous water phase.

Starting from the bottom of the boiler, there is a pipe with an internal diameter of 19 mm (3/4 inch pipe) and with a 19 mm ball valve located 5 cm below the bottom of the boiler. Adjacent immediately to the ball valve is a nozzle consisting of

ISLAND

A 28 mm long brass plug with a centrally located hole with a diameter of 1.28 mm in the form of a piercing. The nozzle plug is inserted into a tube of 19 mm internal diameter and a length of 5.5 m. This tube extends into the flash-5 spinning tank held at atmospheric pressure.

In both experiments, the same materials are used to prepare the flash spin mixture, namely 4800 ml n-hexane, 384 g polyethylene ("Mitsui Hyzex 5Q00P" ® with 3 intrinsic viscosity 2.0 dl / cm) 3200 ml water and 7.7 g 10 "Gelvatol" ® 20-30 polyvinyl alcohol (88% hydrolyzed molecular weight 10,000). However, the way in which these materials are worked up to produce the blend for flash spinning is different for the two experiments.

In experiment # 1 (example of the invention) 15, the boiler is first charged with solvent and polyolefin, then sealed and purged with nitrogen, and its contents are heated to and maintained at 144 ° C with stirring at 100 rpm. per minute for 2 hours to ensure complete dissolution of the polyolefin. The polyvinyl alcohol is then dissolved in the water in a separate container and this solution is heated to approx. 144 ° C. This heated aqueous solution is then pressurized to the boiler containing the heated polyolefin solution at a rate of about 500 ml per minute. This slow and gradual rate of addition causes the water to form the stable phase of the mixture in a stable manner. During the supply of the polyvinylalcoholic water, the stirrer in the boiler containing the polyolefin solution is kept at a stirring rate of 1000 rpm. minute. The stirring of this mixture is continued for 15 minutes, after which the conductivity of the mixture is measured and found to be substantially 0 millivolts, which indicates that the water constitutes a discontinuous phase in the mixture.

In experiment # 2 (comparative example), the processing of the mixture for flash spinning is carried out by the method of Example 4, i.e. the one for trial no.

1 kettle is filled with all material at room temperature,

ISLAND

This mixture is then heated and stirred at the same rate as used in Experiment # 1 to effect dissolution of the polyolefin and dispersion of the polyvinylalcoholic water. After stirring at a temperature of between 110 and 540 ° C for 2 hours, the conductivity of this mixture is measured and found to be above 1000 millivolts, showing that the water is the continuous phase and the polyolefin solution the discontinuous phase in the system.

Thus, in each of experiments 1 and 2, the mixture obtained as described above is then heated to 144 ° C and flash-spun at this temperature and at a pressure of 11.25 ato by the method of Example 4, and the flash-spun material is hydrated using of the equipment described in Example 4 except that the 15 hydra veneer sheets used are of Sprout Waldron pattern P-29-76-B.

Hydrefining is carried out at a content of approx. 3% by weight polyolefin in water. The clearance between the plates is as follows: at first pass 6.4 mm, at second pass 0.6 mm, at third pass 0.3 mm and at fourth and subsequent passages 0.05 mm. The flash-spun material from each test is thus hydrefined until the fibrous product assumes a classified fiber length (CFL) of approx. 1.2 mm. A portion of the products from each test is then further refined by this process to produce a fibrous product having a classified fiber length (CFL) of about 10%. 0.8 mm. The properties of these fibrous products and the properties of hand-made sheets (as described in Example 1) are measured and compared to the following result: 32 146600 CM £ 3

ISLAND

S ΙΟ dP dP dP Μ · j ran σ ro cm m ισ C '1¾¾ p - ^ ^ ^ ^ ^ v (DU O rH CD rH CM <31 00 l £> g fe Μ1 H r- {P Ej _ (D rH g -P CM g A - O '3H © Γ- dP dP dP m *

Q tnH ίι. (O N N βΙ N

O · P * '' '' v 'p (0 o 1-4 M1 ri M1 n CO w

0) 0 fe H CO rH H H

CM H

Cd 'S 00> 6P dP' S *

β] 03 00 (O M1 CO Ol ID CM

Ofe P - ------ {DU O o o in r- o 00 cn

g fe CM rH rH

ρ I

(D r — 4 g -p 00 5 x - tr 30 $ CO dP - dP dP æ ρ Ό in r- ~ vooovom'vo (D O · p - --- »· -

XI P (0 O O rH rH CO CM σι rH

(0 diO fe CM CM rH CO

<X.

P- CO

c: - rH (D 1-3 (D O 'fe

JQ (D U

(OP ^

Eh <D

A 0) • Η Ό fe O 'β & ι Λ, β Λ g C co ra 03

rH -P Q) <D (D

Ρ H g g g Oi <D (D Oi \ Λ Ό o in o \ · • Η P cm co in cm, ¾

Ή O rH g (D

m (D <D X CD

(D 03 -Ρ-P «(0 (D

OQJOiOiCUPHP β (13 · Η -Η Ό Cd Ο

(DH03U3 (D-H <D4J

Ρ <D -Ρ ϋ Ρ Μ Ρ ϋ 0 Ρ (0 0 0 ο 0 0 0 0 0ι · Ρ (0 (0) D Ο Ρ ft Λ Η Ο (ϋ Ή X -Η "θ. 03 Τ3 03) D <D> Ο O '

Μ • PMOiOlg'drHC

03 (OpiOrtSIDIDfet-P

β Β) 0) ΛΛβΛΡβ <D (ΟΛΗρΗββΟ) «θ 'Η -Η -Η -Η (D (ϋ> Ρ)

Η t ^ fe-P-POBSOQ

146600 33

00 VO

In O 'Η CO

44 H a · ©. in cm in o cm ø 44 fe iqn - - Ο V- r- GU <D · P 04 o mm ro oh, ¾ ø Φ p ο oo cm ρ he ø <u fe (d> 1 5 0 Λ Æ D ' -Η φ -ΡΝ ΦΉ -PØ * Η · +> Ρ> ιΗ Λ Ή Ο ιΰ σν νο η Ο β #> ι tn ro oo 01 (1) (1) 0, ¾¾ m οοοο oo oo Ό in ø w - - vd - - Γ "

C tfp p Η P 1-1 o oo O 'oo o H

oø O 0 D> H 0 ^ 04 a irs Λ o <D fe <T> p O '· µ · · »1.0) · ©. in cm h vo o 44 -H La in m 'σι ø 44 -p p ™ o in io oo o vo

C “J 44 0 ro cm H

X <U ^ +> 1¾

Λ Η Λ IH id> idp id βο β (1) -P uo X

*> <0 M w

P tP08 H

0 Η β Η "» -M1 • Γ0 O fe dl bl o · »tJlCiU -Øl CD oo» vo o

Φ ø in, · - ^ η * H

G <κ> Ρ Φ P M o o σι ro o t "

«0 00 (1) 0 U1 CM H

«M £ G fe Η σι

P 44 I D> oo CM

0 0 (16¾ ro cm id o A3 Øgin-, * - oo - o

ø | (H ρ ™ o ro in oo o H

X P> 1CM o CM O '1-1 in øi' fe g -ρ η 0 0 0 D -Ρ> ι · 0 Ρ Η 0 CQ 0 0 0 10 r ~ - in -i — i pti tyi η co

X 01 ^ ¾ -M * CM CO O O

HP 0 # 0 W, - * - CM

00 G O A3 PI Γ 00 "00 ΓΟΟ ο, Q 00 O -H fe 0" »HH 0 0 0 Κ Η 44 U fe Ε4 -Ρ Ρ 0

-ΓΊ Γ '' CM

Dl 44 1 Dl ο "S *

Td ø G 6 ¾ · »'» σι mo G ø 6 ω - * m - m oø, ¾ H p ™ O CM 00 O' O o

and P> 100 o cm H

Uli 'fe -P O 0 0 • P> 1 · Ρ H ø 0 0 0 -¾1 σι n Pj Dl 00 id

Tue P ¾ • M'omooH

ø dP ø in,> »in» »ro βοβιβ PM o oo co oo o m

oø O H fe 0 '»HH H

and H 44 u fe

CM

g i i i

O G G -H

I \ 0 0 P

P0 0 EEG 664-) 4-) ø Φ ^ Φ ro 06-PQ) A3 Η P Di H 1006 ø>,> i GPdPtJiraO'- 'A! 44 +) W O X to

0 0 DI β H 44 0 0 P

G wro ø ρ φ φ ø »P tJiøo, 0 ø 6> ø P ØH <Φ G Φ 0

Di ø \ -Η \ P P H H GffiOJA! pq S O '(¾ S' ffl ffl Di En h .c .G ø

ISLAND

146600 34

By comparing the fiber properties and properties of the handmade sheets made from the fiber products of Experiments 1 and 2 hydrafined to substantially the same classified fiber length, it is readily apparent that the fiber products made by the process of the invention (Experiment 1) are remarkably superior in relative to those obtained by flash-spinning a comparative mixture in which the water constitutes the continuous phase (Experiment 2). The drainage factor of fibers 10 produced by the process of the invention is significantly higher, and also the strength properties of sheets handmade from such fiber products are clearly superior. By visual inspection it can also be stated that in such products fiber bundles and polymer clumps occur only at an acceptable low level.

Claims (7)

A method of flash-spinning polyolefin fibers, in which a mixture containing water, the polyolefin and an organic liquid capable of dissolving or swelling the polyolefin is produced and flash-spun, from a zone of elevated pressure into a zone of lower pressure to evaporate the organic liquid and precipitate the polyolefin as fibers, characterized by flash-spinning a water-in-oil emulsion comprising the water dispersed in a continuous phase comprising the polyolefin and the organic liquid. Process according to claim 1, characterized in that the water-in-oil emulsion is obtained by dissolving the polyolefin in the solvent and dispersing the water in the solution. Process according to claim 1 or 2, characterized in that the amount of water in the mixture is 10-30% by volume of the mixture. Process according to claim 2, characterized in that the water-in-oil emulsion is obtained by vigorously stirring a solution of the polyolefin in the organic liquid, while the water is added to the solution at a slow rate in an amount of more than 30% by weight. volume of the mixture and, per se, sufficient to allow the water to constitute the continuous phase. Process according to any one of the preceding claims, characterized in that the mixture further contains at least a partially water-soluble dispersant for the fibers to be prepared. 0.1% to approx. 15% by weight of the polymer. Process according to claim 5, characterized in that the dispersant is polyvinyl alcohol having a degree of hydrolysis of more than approx. 77% and with a viscosity measured on a 4% aqueous solution at 20 ° C above 2 centipoise. Process according to any one of the preceding claims, characterized in that the polyolefin is at least partially crystalline and is