NO761664L - - Google Patents

Description

Fiber structures of plefin polymers with improved application properties for the production of paper,

and paper made therefrom.

The invention relates to fiber structures of olefin polymers which have particularly good application properties for the production of synthetic or semi-synthetic paper and also relates to a method for the production of such fiber structures as well as paper and paper-like products that use such structures, alone or in . mixture with cellulose fibers.

It is well known that synthetic polymers can generally be used to create fiber structures which are also referred to as fibrils, fibrids, plexo-filamentary fibrils or microstaple fibres.

with a morphology similar to that of cellulose fibres, so that the synthetic fibres. can be used as a full or partial replacement for cellulo-losef! bre in the production of paper and paper products using the methods and in such equipment as are used for the production of ordinary paper.

Such fiber structures do not have a grain shape and at least one of the fiber structures' dimension is smaller than the other two and can also have the form of a film in addition to the fiber shape.

Said fibrous structures or microfibers have a very high absorption capacity for liquids, especially water, and have the ability to form self-supporting mats and webs after spontaneous mechanical filtration. The main characteristic of these microfibers is that they have a surface area (specific surface) of over one m • per gram. Generally, they have a longest dimension of between 1 and 30 mm and a mean diameter or smallest dimension of between 1 and 300 mm.

According to British patent 868.6^1, such microfibers can be produced by adding a solution of a synthetic polymer to a liquid that is not a solvent for the polymer (nonsolvent), and by simultaneously exposing the precipitated polymer or the polymer to the swelling condition for shear forces. A similar method is also described in German patent no. 2,208,553.

According to British patent'1,287,917, structures of similar morphology are obtained, which are similarly suitable as substitutes for cellulose fibers for the production of paper by polymerization of alpha olefins in the presence of coordination catalysts under the influence of shear forces which acts in the reaction mixture.

Other methods by which fiber structures with the above-mentioned properties and application area can be produced and where the products are obtained as more or less coherent aggregates or fibrillated filament structures (plexofilaments) consist of extruding through an opening emulsions, dispersions or suspensions of synthetic polymers in solvent mixtures , .emulsifiers or dispersants or mixtures thereof, during practically instantaneous evaporation of the solvent or the liquid phase present (flash spinning). Procedures of this type are described e.g. in British patent 8.91. 9^3 and 1,262. 531 and in US Patent 3,770,856, 3,7<!>+0,383 and 3,808,091, Belgian Patent 789,808, French Patent 2,176,858 and German'Patent 2. 3^3. 5'+3 •

The fiber aggregates or plexofilaments produced using these methods can be easily broken up by painting or cutting until you have fiber structures with a surface area of over lm 2 per. gram which is suitable for use in the manufacture of paper and other similar products.

3ritic patent 891.9<!>+5 describes e.g. production of such fiber structures, (plexyf ilamentf ibrid s) by breaking up

of plexofilaments produced after flash-spinning of polymeric solutions.

Finally, one can produce fibrils or fiber structures with a similar field of application by treating a solution or, suspension, emulsion or dispersion of polymers in

solvents and/or emulsifiers or dispersants during extrusion during rapid evaporation of the liquid phase at the same time as the extruded strand is exposed to shear from

.a gas at high speed directed at the extruder string in a

certain angle.

Procedures of this type are described in Italian

patent 2959Li-A/7>+, in the name of the present applicant.

The possibility of using the above fibers of poly-olefin compound as a partial replacement for cellulose fibers in paper entails the main difficulty that these fibers have poor adhesion within the paper's structure.

Consequently, the paper's mechanical properties will deteriorate

with an increased content of polyolefin fibres.

If one who. characteristic term for the paper's mechanical properties, user, wear length (SL), you will find that this figure can fall to less than a third of the corresponding figure for cellulose paper when the paper contains 30% by weight of polyolefin fibres.

Soker has now found that polyolefin fibers have better possibilities for use in papermaking in that they have increased mutual adhesion to each other or to cellulose fibers if they contain, at least on the surface, one or more nitrogen-containing polymer compounds with one of following formulas:

where p is a number which can be 0 or 1 .and A-^, B and A ? can have different sizes depending on the size of p, and more especially: when p = 1, A-^and A^ can independently be groups

or also, but only when 3 is different from et-piperazine radical, groups of the type

mehsB may be a nitrogenous group of the type

or (piperazine)

, however, when p - 0, A-^ can be a group

or

while 3 may be equal to A-^'or a group of the type

and in this case the molar ratio A-^/3' in the macromolecule is between 1:20 and ^:'1, and where in addition: R = H, an aliphatic' group with from 1 to 20 carbonate atoms or a cycloaliphatic. or aromatic group with from 6 to 10 carbon atoms,

R2=. an alkyl group. with 1 to h carbon atoms, R^ = H or-CH^,. X = an alkyl group with from 1 to 20 C atoms where one or more hydrogen atoms may be replaced by hycroxyl, alkyl, amine or allylamine, or where X may be a group:

m = an integer between 0 and h inclusive

y =.an integer between 1 and 3

z an integer between 1 and 20

n = a random number between 5 and 100 when p = 1 and between 5 and 1000

when p = 0.

B and D = -N-K-N groups or

R R

K = alkylene number ad in cal with from. 1. to- 6 C atoms,

R = an aliphatic group with 1 to 20 C atoms or a cycloaliphatic-aromatic group with 6 to 10 C atoms,

R2= an alkyl group with 1 to 3 C atoms,

m = an integer between 0 and 2,

n = a lame number between 5° and 500,

where B, D and n have the same meaning as under formula (I):

where: FU= an alkyl group with 1 to h .C atoms,

n = an integer between .10 and 300.

Compounds within class (I) are generally known. They can be prepared by polycondensation of epichlorohydrin or Li-chloro-1,2-epOxybutane (or their R-derivatives which are chain-substituted) with one or more primary amines and/or . secondary amines with formula:

and by any subsequent modification which may consist of substituting the hydrogen atoms that are bound to the carbon atoms in the chain with R radicals" in the usual way within organic chemistry and/or etherification of at least part of the hydroxyl groups after the polycondensation with ROH alcohols, esterification with R -C00H acids or substitution at least partially with chlorine, bromine, iodine, amide or alkylamine

by

known methods in organic chemistry.

The above polycondensation reaction is generally known. It can, for example, be carried out as described in articles by: C. Caldo 1 "Chimica e Industria" vol<!>+9 no. 10, October 1967, pages 915 and 10'+7 and "Die Makromolekulare Chemie" 116 (1968)', pages 158-172, ' and partly in US patent 3A75,518 and - 3. 527.8>+6 in the name of the present spker.

Preferred primary and secondary amines suitable for said polycondensation reaction are ethylamine, propylamine, n-butylamine, n-pentylamine, n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, n-octadecylamine, n-hexadecylamine, n- octadecylamih, laurylamine, cyclohexylamine, aniline, tetramethylenediamine, pentamethylenediamine, dipropylenediamine, diethylenetriamine, ditriethylenediamine, tetraethylenepentaamine, N,N'-diisopropylhexamethylenediamine, 1,'3-bis, (n-dodecylamino)-2-propanol,- N 'N.' -dibutyl-hexamethylenediamine, -bis-(methylamino)-diphenylmethane, N,N' -dicyclohexyl-hexamethylenediamine, piperazine, trans-2,5-dimethylpiperazine, 2-methylpiperazine, 1+,1h-' -bis-(ethylaminep) - 3,3'-dimethyl-diphenyl-methane, hexamethylenediamine, 1,2-propylenediamine.

Compounds in class (I) can also be prepared

according to a known reaction between a,tJ -dihalogen derivatives of ethane, propane and butane or their corresponding R-substituted derivatives and primary and/or secondary amines with formulas:

General information on such separation methods can be found in "Methoden der Organischen Chemie" Houbel Weil, volume lh/2, pages <1>+55, ^77, '+87 and 590. •

Slant preferred dihalogen derivatives. one can mention:

1,2-dichloroethane, 1,3-dichloropropane, 1, ^--dichlorobutane.

When p = 0, compounds with formula (I) fall under the following classes:

(a) polyvinylpyridines,

(b) copolymers between vinylpyridine and amides of α,β-unsaturated acids containing 3 to 6 C atoms, e.g. acrylic, methacrylic, vinylacetic and vinylpropionic acids, (c) Reduction products of said copolymers which can be prepared by F. Danusso and P. Ferruti in an article in: "Chimica e Industria" 1968, 50-, 71 where it occurs instead a reduction of the amide group to a primary amine group, and finally (d) reduction products of homopolymers of amides of a,B-unsaturated acids containing 3 to 6 C atoms, according to the article by F. Danusso and P. Ferruti, who is mentioned above.

With respect to classes of products (b) and (d) examples of preferred amides are: N-isopropylacrylamide, N,N-dimethylacrylamide, N-phenylacrylamide, N-cyclohexylacrylamide, N-ixopropylmethacrylamide, N-methyl-N-phenylacrylamide , N-a-naphthyl-acrylamide, N-dodecyl acrylamide, N-benzylacrylamide. Connections

•with formula'II, II and IV are also known. Compounds with formula

I can be prepared by reacting an ester of an acrylic acid with e'tt

or', several secondary diamines of formula:

as described by F. Danusso and P.. Ferruti i

an article in "Polymers" 88, Volume 11 (2) 1970.

Products belonging to the class with formula (III) can

are produced by reacting divinyl sulfone with one or more

disecondary diamines of formula

or'

as described by F. Danusso and P. Ferruti in a

article in. "Chimica Industriale" 1967,>9, 826.

Examples of preferred diamines for the preparation of compounds in class II and III are: ethylenediamine, propylenediamine, hexamethylenediamine, piperazine.

Compounds in class (IV) can be prepared by polymerization of diallylamines according to the method described. by Youji Negi, Susumo Harade, Osamu'Ishuzuka in "Journal of Polymer Science", Volume 5, A (1)(1967) at pages- 1951-1965.

The possibility of using microfibres or similar polyolefin fibers containing said nitrogen compounds for the production of paper depends on the ability of the nitrogen compounds to esterify. or adhere to the fiber surfaces during the mechanical mixing with water and possibly with cellulose. which is included as a necessary feature in the production of aqueous paper pulp.

and depends on whether the microfibers have a correction energy that is at least equal to the fibers' own correction energy. - On the other hand, nitrogen compounds must be avoided. differs from the fibrils during paper production also for the reason that the presence of a non-fibrous separate phase in aqueous paper pulp reduces the paper's surface properties and the paper's mechanical strength, in relation to the amount present.

For the purposes of the invention, it is necessary that at least part of the nitrogen compounds found on the fiber surface are not removed in quantities of over<>>+00 parts per million for

every grinding hour in the Lorentz-Wettres-type Dutchman (moll), under pitch-refining conditions. in TAPPI stand ard TAPPI T-200, under zero load.

Depending on the type of nitrogen compound, the amount and thickness of the layer on the fiber surface and depending on the way in which the nitrogen compound is introduced, it may happen that the outer parts of the compound are removed more easily and faster than parts that are close to the fiber. During treatment in the Dutchman under the specified conditions, it may therefore occur that nitrogen compounds are lost which initially exceed ^-00 ppm/hour, with the loss later, however, stabilizing more or less

.quickly to a value' that is below this.

Thus, a feature of the present invention consists in

a. providing microfibers of olefin polymers suitable for the complete or partial replacement of cellulose fibers for the production of paper, which microfibers contain, at least on the surface, one or more nitrogen-containing polymers selected from compounds of the general formula:

where p is a number equal to 0 or 1,

A-^, B and Ag may have different meanings' depending on the value of p, and more particularly:-

when p = 1, A-^and A^ can independently denote groups with formula:

or also, but only when B is different from a piperazine radical, groups of the type while B can be a nitrogen radical of the type or when, on the other hand, p = 0,. can A-^be a group with formula: or have the same meaning as A-^or be a radical with formula and in the latter • case the molar ratio lies. between A-^ and B on . between 1:20 and<!>+:1, and where in addition: R = H, an aliphatic radical with 1 to 20 C atoms or a cycloaliphatic or aromatic radical with 6 to 10 C atoms, Cl,. Br , J, ; D = a nitrogen radical of the type

where Rg = an alkyl radical with from 1 to h C atoms, R^ = H

or -CH ,■

X = an alkylene radical. with from 1 to 20 C atoms where one or more hydrogen atoms may be replaced by hydroxyl groups, alkyl, amine or alkylamine groups or where X may be a radical of the type:

m = an integer between 0 and ^

y = an integer between 1 and 3,

z = an integer between 1 and 20,

n.= an integer between 5 and 100 when p =1, and between 5 and 1000

when p = 0.

where 3 and D can independently be nitrogen radicals of the type or ...

K = an alkylene radical with 1 to 6 C atoms,

R = H, an aliphatic group with 1 to 20 C atoms or a cycloaliphatic or aromatic group with from 6 to 10 C atoms, Rg^ an alkyl radical with from 1 to 3 C atoms,

m =--an integer between 0 and 2

n = an integer between 5°g 5°05

where Bog D' can independently be nitrogen radicals of

K = an alkyl group with 1 to 6 C atoms,

R = H, an aliphatic group with 1 to 20 G atoms or a cycloaliphatic or aromatic group with 6 to 10 C atoms,

Rg= an alkyl group with 1 to 3 C atoms,

m = an integer between 0 and 2,

n = an integer between 5 and 500,

where: R^= .an alkyl group with 1 to h- C atoms,

n = an integer between 10 and 300,

which microfibers are characterized in that they have a surface area of over 1 tr^/g and in that at least a part. of the nitrogen compounds on the surface cannot be removed in amounts stbrre than ^-00 ppm per hour by treatment in a Lorentz-Wettress Dutchman under grinding conditions following Tappistandard TAPPI T - 200 os 70, under zero load.

Fibers containing on the surface nitrogen compounds that cannot be removed under the above conditions in an amount of

0.5% by weight of the combined weight of fiber and said compound can already be considered satisfactory for the purposes of the invention, but amounts of said nitrogen compound of between 0.5 and 10% on the fiber surface are preferred. Amounts in excess of $10 will generally not be beneficial or necessary, although such larger amounts in certain cases and for certain 'nitrogen compounds' will enable further improvement of the fiber's field of application, this

for, economic reasons and because of difficulties with inner workings in the fibre.

The -olefin polymer which forms the fiber base according to the present invention can be HD-polyethylene, polypropylene which essentially contains isotactic macromolecules, poly-^-methyl-pentene-1 or a copolymer ethylene-propylene either randomly distributed or as a block polymer.

The flbrilles or microfibres which. contains nitrogen compounds, according to the invention, can be produced in different ways. One method consists in mixing the polyole fine materials, regardless of origin, provided that these have a surface area of more than 1 m p/g? with a concentrated solution or suspension of one or more nitrogen compounds in water or another liquid diluent, and then filter and dry the fibers at a lower temperature than the softening temperature of the polyolefin.

Satisfactory results have been obtained with solutions or suspensions containing several nitrogen compounds which have different softening temperatures, the lowest of which has at least 10°C lower softening temperature than that of the polyolefin, and by drying the treated fibers at this lower temperature. The treatment of the fibers can be repeated several times depending on the nitrogen compound used and the amount that one wants to deposit on the fibers. The fibers turn out to be easily dispersed after drying. Only in water under gentle stirring.-.

A suitable method which enables the rapid production of fibers according to the invention and after which the nitrogen compound has

great adhesion to the fiber surface, consists in extruding-through an opening a solution, emulsion, dispersion or suspension, of the olefinic polymer in one or more liquid media during practically instantaneous evaporation of the liquid phase (flash-spinning), which solution , .emulsion, dispersion or suspension -contains one or more.of those. above defined

■ nitrogen compounds.

Soker has found that under such conditions the nitrogen compounds arrange themselves on the surface of each fibril or microfibre which forms the aggregates or plexofilaments which are known to be produced by such extrusion. In general, quantitative analysis carried out with such microfibers, which is described in more detail later, has shown that at least 60% by weight of the nitrogen compounds bound to the fibers in such cases are arranged on the outside of the fiber surface, while the rest is located in the fiber's surface zone.

These results can be achieved by following any method that enables the transformation of the olefin polymer into fibers either as single fibrils or in the form of more or less complex and stable aggregates, by extrusion ■■ of solutions, suspensions, emulsions or dispersions of polymers in one or more liquid media through an opening, under such temperatures and pressures that relatively instantaneous evaporation of the liquid phase in the system is achieved.

Some of these methods are described in the previously mentioned patents and publications which deal with the "flash-spinning" method starting from different systems and operating conditions. Among such descriptions, mention is made of Italian patent 9^7,919 and Italian patent application 2959*+ A/7^, both of which have been mentioned previously.

When the extrusion products consist of aggregates of microfibres or fibrils, these can be broken up in a Dutchman or by other suitable methods for the production of single fibers with such dimensions that they can be used directly for the production of paper.

According to this second method of preparation, the nitrogen compounds are added to the polyolefinic mixture to be extruded in an amount of at least 0.5% by weight of the total weight

. of polyolefin and nitrogen compound, and preferably in a

amount of between 0.5 and 10% by weight of the total weight.

The nitrogen compounds can be either soluble or insoluble in the system during extrusion.s temperature and pressure. Inorganic fillers and wetting agents of various types can be added to the extrusion mixture.

Thus, another aspect of the invention is to provide

provide a method for the production of fibrils or microfibers containing nitrogen compounds according to the definition, consisting of extruding through an opening a solution

■or an emulsion, suspension or dispersion of an olefin polymer in one or more liquid media containing between approx. 0.5 and 10 wt% polymeric nitrogen compound as defined by one or more of the general formulas I to IV above, during practically instantaneous evaporation of the liquid phase.

As mentioned, fiber structures according to the present invention show improved applicability for the production of paper according to the usual method.

In US patent 3,669,829, the applicant has described the production of a semi-synthetic paper using traditional methods, starting from aqueous suspensions containing cellulose fibres. ordinary mono-drawn polypropylene fibers and 0.1 to 10% by weight binder consisting of polycondensation polymers of epichlorohydrin with primary and secondary amines of aliphatic, aromatic or heterocyclic type. The way nitrogen enpolymers according to the US patent are used makes it currently not possible to produce fiber structures according to the present invention, as the nitrogen compounds according to the method described in the patent arrange themselves on the cellulose fibers (due to the cellulose's high adsorption capacity for these compounds), with the result that the surface of the fibers changes significantly, while the polyolefin fibers are practically uncovered.

Paper which consists either wholly or partly of polyolefin microfibers according to the invention in itself shows mechanical properties that are better than for paper made with similar polyolefin fibers as such.

It has now surprisingly been discovered that the mechanical properties can be further improved if at least part of the macromolecules of the nitrogen-containing compounds on the fiber surface are brought to react with a polyacid selected from among the following, through one or more of the basic nitrogen atoms on the fiber surface: Polyacrylic acid , polymethacrylic acid, polyitaconic acid and alginic acids.

According to this reaction, a basic nitrogen atom reacts with at least one carboxyl group on the polyacid to form the corresponding salt, however, the reaction can also consist in the formation of secondary bonds between the basic nitrogen atom itself and several carboxyl groups on the polyacid (normally .up to five such carboxyl groups).

The reaction between the polyacid and the nitrogen compound can be achieved by treating the microfibers containing the nitrogen compounds with. an aqueous solution • of polyacid. The concentration and temperature of the solution can vary within wide limits. It is generally advantageous to use a solution. containing from 0.05 to 5% by weight polyacid, higher concentrations may be used,

but when you want to reduce the reaction time, depending on the molecular weight. we scosity and up.looseness for. polyacid in water. The turnover can take place at room temperature and in practice temperatures between

0 and 80°C are used. Under the stated conditions, one reaction time, i.e. a residence time for the microfibers in the polyacid solution,

in between a few seconds and 5 minutes usually give .satisfactory results. Longer reaction times offer only small advantages due to the slower rate at which the polyacid reacts.

gers with the immediately underlying parts of the nitrogen compounds.

After treatment, the microfibres can be filtered, optionally washed with water to remove excess polyacid and processed into sheets or can be sent to papermaking using normal methods, optionally after mixing with cellulose fibres.

The reaction with polyacid can also take place on the paper formed with microfibers according to the invention or on the corresponding output plate according to previously known "size-pressing", i.e.> by impregnating the paper or plate with a solution of polyacid under the aforementioned conditions, then removal of excess polyacids by squeezing and possibly washing with water and subsequent drying of the sheet at temperatures between 95 and 110°C. The treatment can be carried out continuously by feeding the sheet of paper or fibreboard from the wire cloth, preferably with a moisture content of 20 to 180%, into containers containing the polyacid solution, then pressing the surface or web impregnated with the solution between press rollers after any intermediate washing in water and final drying between normal drying cylinders at 95 to 110°C.

A variant of the above method which gives similar results consists in impregnating the microfibers with nitrogen compounds or corresponding sheets or plates (webs), with an aqueous solution of an acidic compound or a compound which can give off acids, e.g. aluminum sulphate, and then treat the impregnated products with an aqueous solution at a pH of approx. 7 to 9 of a polyacid which is partially salted with an inorganic or organic

base (e.g. NaOH, amine, ammonia) and finish the process with squeezing and/or washing and using as described above.

Another feature of the invention is thus to provide microfibers or fibrils that contain nitrogen compounds according to the given definition where at least part of the macromolecules of nitrogen compounds on the surface of the fiber structure is chemically bound through one or more of its basic nitrogen atoms to carboxylic acid residues in a poly-

acid selected from polyacrylic acid, polymethacrylic acid, polyitaconic acid and alginic acids.

Another aspect of the invention consists in paper which is produced wholly or partly from microfibres as defined above. nerd.

In the following examples, which should not be construed as limiting, the production of microfibres in accordance with the invention is illustrated. The fibers in each example are used for the production of synthetic or semi-synthetic paper according to the specified methods, with paper qualities such as properties and amounts of nitrogen compound bound to the fibers in each example were measured as follows: Immediately after manufacture, fibers with nitrogen compounds were treated in a Lorentz-Wettres Dutcher under grinding conditions according to TAPPI T- 200 os. 70, zero load,

to. find the amount of non-removable nitrogen compounds,

as the amount of such removable nitrogen compounds must be below ^-00 ppm per hour treatment. During painting, the amount of nitrogen compounds bound to the fibers and the amount in the liquid phase are measured by acidimetric titration of. the basic nitrogen and/or nitrogen analysis according to Kjelldahl for corresponding pro-

be taken.from the Dutchman. In general, it became clear that loss of nitrogen compounds from the fibers stabilized very quickly at the above-mentioned limits after a more or less strong initial

loss, and in some cases stabilized almost immediately.

The acid analysis carried out on the fibers was carried out using a conductivity meter of the type F 39 from Wiss Tech. Werk-staetten, Weieheim, on samples of approx. 1 gram of fibers dispersed in 100 ml of distilled water, with the addition of HC1 0.002 N.

In acidimetric analysis, the total amount of basic nitrogen present on the fiber surface was titrated, with the end point of the reaction being indicated by a sudden displacement of the conductivity meter's arrow on the color scale and by the arrow holding. in this position for about 30 seconds.

Based on special calibration curves for each nitrogen compound, the amount of each nitrogen compound on the fiber surface was calculated. The amount of nitrogen compound which was possibly embedded in the surface zone of the fibre, and whose detection at

■an acidimetric method would have required far too long reaction times, could be calculated from the difference from the amount of total nitrogen bound.ti! the fiber, measured according to Kjelldahl.

For the production of semi-synthetic paper, cellulose was used in the form of a mixture of equal parts bleached birch cellulose and Scandinavian pine cellulose at grinding degree (°SR) = 30.

In each trial, paper was made from an aqueous pulp containing 20 g/l fibres, regardless of whether the fibers consisted only of microfibres according to the invention or mixtures thereof. cellulose, and the sheets were formed in the usual manner on a continuous paper machine, dried between cylinders at 100 to 110°C and a pressure of 50 kg/cm 2 for 5 to 60 seconds. Treatment with polyacids was carried out by impregnating or dipping the produced sheets in an aqueous solution, at room temperature, containing 2% by weight of polyacrylic acid with a pH between !+■ and 5 and viscosity approx. 20 centi-■poises measured at ,.20°C. One minute after impregnation of the sheets, they were quickly placed between two pressure rollers and dried, at 100-110°C.

The wear length (SL) of the paper indicated in the associated tables is measured according to the ATICELCA MC2/68 standard. These figures only have to be compared with corresponding figures for paper sheets made of only cellulose of the described type produced in the same way, the wear length being approx. 6,500 before treatment with polyacrylic acid solution and after treatment approx. 6800.

Example 1

Preparation of nitrogen compound with formula:

10 mol of diglycidylpiperazine (produced by condensation of piperazine with epichlorohydrin in a molar ratio of 1:2, in a known manner) and 10 mol of cyclohexylamine and 6 1 of isopropanol were charged into a reactor equipped with stirrups and reflux skirts. The mixture was then heated to approx. 82°C for 5 hours after which the solvent was distilled off at reduced pressure to dryness. The product was a solid substance with softening temperature approx. 5°C. By nitrogen analysis (Kjelldahl), the product showed a nitrogen content of 1^-weight (theoretically equal to 1<L>i-.7%). Mean molecular weight according to osmometric analysis was lh.l0^,' which indicates n=l1+.

Manufacturing. of microfibers according to the invention.

For this preparation, a method and apparatus were used as described in Italian patent application No. 29591+ A/7^, to which reference is made. According to a general method described in the patent, a solution, emulsion or dispersion of the polymer in a liquid mixture is extruded during practically instantaneous evaporation of the liquid phase through nozzles (5) in the area formed in the spreading part (<*>+) in the convergent divergent nozzle (1).

A stream of gas (6) passes through the convergent portion (2) and the constriction (critical) (3) in the nozzle and collides at an angle and at high speed with the extruded mixture spread section. Upon impact with the extruded mixture, the liquid has a lower temperature than the dissolution and/or softening temperature of the polymer/residual liquid system in the polymer.

■ The nozzle used has a circular cross-section (critical)

-of 6.5 mm and maximum diameter in the spread section (divergent section) of 15.^'2 mm. The distance between the critical six ion and

the maximum section is 31.8 mm.

In a 300-liter pressure vessel equipped with rudders and a heating jacket, 10,000 kg of polyethylene of the HD type (M.I.= 5, melting temperature_= 132°C) and 0.31 kg of pre-produced nitrogen compound (corresponding to approx. $ nitrogen compound on the basis of the total weight incl. polyethylene), and 80 1 n^-hexane.

The autoclave was heated until a solution of olefin polymer in the solvent was obtained at 180°C and a pressure of

12.3 atm. Under these conditions, the solution (7) was extruded into the spreading section (k) described above through eight nozzles of cylindrical shape, all with a diameter of 1.5 mm, arranged uniformly around the said end part of the spreading section (maximum diameter). Steam at 10 atm was used as the gaseous medium.

pressure and approx. 200°C temperature at the entrance to the spreading section (2).

The ■ flow rate of the solution through each nozzle was approx. 100 l/h, the steam pressure corresponding to the end part of the spreading section was close to atmospheric pressure.

A product was obtained which, on microscopic analysis, showed

to consist of separate microfibers with a length between 3 and 6 mm, average length 5.8 mm, average diameter equal to 27/j.. Surface area-p

let was 5 rn /g.

50Q g of the manufactured fibers showed after 10 minutes of grinding in Holland under conditions according to TAPPI T-200 os.70 under zero load, a nitrogen loss (loss of nitrogen compound) of less than h00 ppm, per subsequent painting class.

In nitrogen analysis according to Kjelldahl, to which the fibers were exposed after the treatment, the amount of total nitrogen compounds was found to be equal to 2.8 weight$ of the total weight of the fibers (fibres + nitrogen compound).

By acid analysis, the amount of nitrogen compounds on the fiber surface was measured at 2.5% of the total weight, thus corresponding to 90% by weight of the nitrogen compounds on the fibers.

The microfibers after the Hollander paint were used for the production of paper sheets according to the above method.

Example 2:

A 2-hour liter autoclave was filled with 0.8 kg of polyethylene of a similar type. as in Example 1, 0.0*+ kg nitrogen compound of the same type -(corresponding to '+.7$ Pa basis of total weight) and 8 1

n-hexane. The autoclave was then heated and a solution of polyolefin in hexane was obtained at a temperature of 185°C and below

an autogenous pressure of -13 atm, and under these conditions the autoclave contents were extruded through a nozzle with a diameter of 1.5 mm and a length of 1.5 mm.

This resulted in a strongly fibril-shaped fiber consisting of a very large number of fibrils joined at the ends and arranged at different heights (plexofilaments)■. These filaments were broken up in a Lorentz-Wettres Dutch end under a 2.5 kg load,• to a concentration of 50 g fiber per liters of water. After 20 minutes from the beginning of the painting, the fibers were completely torn apart into single fibers with a length of approx. 3 mm,, apparent diameter (mean diameter) equal to 22/Li and surface area of 5 m o/g'

In the Kjelldahl analysis, the total amount of nitrogen compound bound to separate fibers was 2.6% of the total weight of fiber and nitrogen compound. Loss of nitrogen compound when grinding the fibrils in Lorentz-Wettres-Dutch under zero load according to Tappistandard T-200 as.70 was below ^-00 ppm.. per hour. The amount of nitrogen compound on the surface of the fibers was 2.0% of the total weight (equal to 92% of total nitrogen compound).

Example

Preparation of a compound of formula:

A reactor was filled with 3 moles of diacrylic oil-piperazine,

3 mol N,N<1->dlisopropyldimethyldiamine and water to a monomer concentration of approx. 30 weight$. The mixture was reacted for 8 hours at -100°C with constant stirring, whereupon the reaction mixture was cooled and the formed polymer separated by crystallization. The polymer had a melting point of 97°C.

Production of microfibres.

In a pressure vessel of the same type as in Example 1, 9 kg of HD polyethylene (M.I.=<>>+, melting temperature = 132°C) and 0.6 kg of nitrogen-containing polymer prepared as above were filled and

210 1 n-hexane. Mixtures were heated to 178°C which gave a pressure of 1<f>+.6 atm and were extruded in apparatus as described in Example 1, with a flow rate of 100 1, per hour per extrusion nozzle, using steam as the cutting medium as described in the same example. Separate fibers with a length between 2 and h mm and an average length of 2.8 mm, an average diameter of 16/lZ and over-

p

surface area 6.1 m /g.

Amount of nitrogen polymer totally bound to the fibres

was 5.98$ of total weight (fibers + nitrogen polymer).

90% of the nitrogen polymer, corresponding to 5.38% on a total weight basis, was placed on the fiber surface. After a 20-minute treatment in the Netherlands under zero load according to the TAPPI standard as indicated earlier, the loss of nitrogenous

polymer below ^00 ppm per hour which was equal to 2.8$ of the total weight of the fibers on the fiber surface.

0

Example *+

Preparation of a compound of formula:

Polyacrylamide with a viscosimetric molecular weight equal to 1.2.10 produced by polymerization of acrylamide in the presence of azo-bis-isobutyronitrile in a known manner was dissolved in methyl alcohol to a concentration of 20 g/l and reduced to 25°C temperature by the addition of NaBH1+ and CoC^.ét^O in concentrations of 57 g/l and 71 g/l, respectively. • The reaction product was purified by dialysis. It showed a content of amine groups corresponding to 5.0 milliequivalents of KOH/g, again corresponding to a molar ratio

of approx. 2:1.

Production of microfibres.

The same apparatus was used as in Example 1 with 8 kg of polyethylene in 80 1 n-hexane and 0.8 kg of reduced polyacrylamide prepared as above, by extrusion<g>; of the polymer solution at 170°C and an internal pressure of 10, k atm and a flow rate of 100 l/hour per nozzle.

Steam was used as the cutting medium as described in • ■

Example 1.

The fibers had a length of between 2.1 and 3 mm, mean value 2.3 mm, mean diameter 22/j. and surface area ^.6 m 2/g.

After grinding for one minute in Dutch under previous conditions, the fibers showed a nitrogen compound loss of 9% by weight of the total weight of the fibers, of which 92% (equivalent to 8.28% absolute) was found to be on the surface of the fibers.

Example 5

■'Preparation of a compound of formula:

A five liter container was simultaneously filled, at room temperature and over the course of 1.5 hours, with 8 mol of dimethylamine which

h0% aqueous solution, h mol allyl chloride and 10 mol NaOH in a 50% aqueous solution. After keeping the mixture at room temperature for 30 minutes, it was heated at 62°C for 5 hours whereupon an oily layer was separated which had formed and from which the dimethylallylamine was worked up by distillation.

The dimethylallylamine was then quaternized by dissolving in anhydrous acetone with a stoichiometric amount of allyl chloride, after which the mixture was allowed to stand for 10 hours. The precipitate consisted of dimethyldiallylammonium and was filtered off.

335 g of this chloride was dissolved in 19<*>+ g of water under a nitrogen-free atmosphere together with 5 ml of t-butyl hydroperoxide, and the solution heated at 60°C for<>>+5 hours, after which it was evaporated to dryness under reduced pressure. The product was a polymer of quaternized dimethyldiallylamine of the above formula.

Manufacture of fibres.

In a dissolution autoclave as described in Example 1

if you filled 8.5 kg of polyethylene of the same type as in this example,

as well as 0.5 kg of the polymer produced above as well as n-hexane

a solution which gave a polyethylene concentration equal to M+.0 g/l.

The solution was extruded in the same apparatus and under the same conditions as in Example 1, to fibers with a length between 3 and 5 mm, mean value 3.5 mm, and diameter 22/in and surface area M-.3 m 2/g.

After 50 minutes of Dutching in a known manner, the fibers showed a nitrogen compound loss of less than ^00 ppm. per hour of treatment, corresponding to a total amount of bound nitrogen compound on the fibers equal to 2.58$ of which 90$ (equal to 2.2h% of the nitro<g>e<n>compounds on the total weight of the fibers) was spread over the surface.

Example 6

Preparation of compounds with formeir

. 1.8 mol of N,N'-bis(2,3-epoxypropyl)-piperazine as well as 1.8 mol of octadecylamine and 10 1 of isopropanol were filled into a reactor provided with stirrups and reflux skirts.

The mixture was reacted for 5 hours at 82, and then the isopropanol was distilled off in vacuo with a solid residue containing 9.00% N, consisting of the polycondensate of the above formula.

Production of fibers:

For this purpose, the apparatus was used as described

in Example 1, starting from a solution of HD polyethylene (M.!.=>+, 5, melting temperature equal to 132°C) consisting of 8 kg polyethylene, 0.2 Lt- kg pre-produced polycondensate and 80 1 n-hexane. The solution was extruded under the following conditions: Temperature f 175°C, pressure = 11 atm., flow rate = 100 1 per hour/nozzle..

Steam was used as the cutting medium under the same temperature and pressure as in Example 1. The fibers had a length of between 3 and 5 mm, mean diameter 3% and surface area = h m /g.

500 g of the fibers were beaten up in a Lorentz-Wettres Dutchman under the previously stated TAPPI standards and zero load. After approx. 10 minutes of treatment stabilized the loss.' of nitrogenous compound amounts to less than ^OO.pprri per hour.

Under these conditions, the analysis showed a quantity of nitrogen compound that was bound to the fibers in total equal to 1.5$ of the fibers, total weight of which approx. 93$ (corresponding to 1.<!>+ weight$ on pasis of the total weight of the fibers) was distributed on the outside of the surface of the fibers.

Example 7

Preparation of compounds of formula:

2.2 mol of anhydrous piperazine and 2 mol of epichlorohydrin and 600 ml of ethanol were filled into a wooden-necked flask fitted with stirrups and reflux skirts. The mixture was stirred for 1.5 hours, heated at 78°C for 8 hours and then for 3 hours under slow addition. ning of 2 mol NaOH. The sodium chloride formed was filtered off and the filtrate precipitated with 1800 ml of acetone. The white precipitate was separated and dried at 100-110°C.

The product was resinous and had a softening temperature of about 200°C.

Production of microfibres.

Apparatus was used as described in example 1 and

a solution of 8 kg of polyethylene in 80 l of hexane, containing 0.5-0 kg of the above nitrogen compound. The solution was extruded at; 170°C and a pressure of 10.<>>+ atm with a strain rate of 100 1 per hour per nozzle.

Steam was used as the cutting medium at the same temperature and pressure as in example 1, and fibrils with a length between 2

and h mm, mean diameter 23pt and surface area 5.5 m /g.

After approx. 20 minutes of treatment in Holland under the usual conditions, the microfibers showed a nitrogen compound loss of less than k- 00 ppm per hour's treatment corresponding to a total content of 2.2% by weight of nitrogen compound, of which 95% was on the fiber surface.

Example 8

In a pressure dissolver, 8 kg of polypropylene (M.I.=6.7, melting temperature 165°C) and n-pentane were filled in such a quantity that a solution with a concentration equal to 50 g/l polypropylene was obtained. The solution was then heated ■ to 160°C and, under a pressure of 17.6 atm, transferred to fibers in apparatus as described in Example 1. The flow rate of the solution was 100 l/hour' per nozzle. The cutting medium was used steam with output temperature and pressure as described in Example 1.

The fibers produced had a length of 3 to 5 mm, average length .2 mm, diameter. 20/2 and surface area equal to ^.8 m /g. The fibers were suspended in water with a concentration of 30 g/l with a pH equal to Lt-1 adjusted with sulfuric acid. Reduced <p>ol<y>acr<y>amide of a similar type as in Example h was added to the suspension in an amount of 1.5 g/l suspension. The polyacrylamide was added as a salt in 1.5 wt% aqueous solution of HgSO 4 0.2N.

To the suspension, 5% aqueous NaOH was slowly added to a pH equal to 6.8. The suspension was filtered and the fibers washed with water in an amount of 1 liter per 30 g of fiber. The fibers were dried at 80 o -C. ■ The surface area was ^.2 m 2 /g. 500 g of microfibers were milled, in Lorentz-Wettres Dutch under zero load under the previously mentioned TAPPI standard.■ After 5 minutes of treatment, the polyacrylamide loss stabilized to below ^00 ppm per hour which corresponded to a total content of polyacrylamide bound to the fibers of ^.5$ of the total weight of the fibers and polyacrylamide. Acidimetric and nitrogen analysis showed that the entire polyacrylamide was distributed over the fiber surface.

Example 9

Preparation of a compound of formula:

A three-necked flask was filled with 3<1>+7.7 g of divinyl sulfone and approx.<!>+800 ml of a mixture of methanol and water in a volume ratio of 10:6, then 29^ g of 2-methylpiperazine were added under a stream of nitrogen. The mixture was cooled to room temperature and left under these conditions for 2 hours. The reaction product was completely. into a mixture of ether and acetone in a 1:1 volume ratio and the polymer precipitated as a rubbery product which was decanted from and washed with anhydrous ether and then dried.

Production of microfibres.

The fibers were produced as in Example 3 under the same operating conditions. conditions with the difference that the nitrogen compound used was the above, in the same amount of 0.6 kg. The produced fibers had a length between 3 °g and 5 mm, a diameter of 30/2 and a surface area equal to 5.8 m 2 /g. After painting in Holland at zero load, the fibers showed a nitrogen compound loss of less than >+00 ppm per hour corresponding to a quantity on the fiber surfaces equal to ^.8 weight$.of. their total weight. The total amount of nitrogen compound bound to the fibers was 5.3% of the total weight.

Claims (9)

1. Fibers of olefin polymers. suitable for "full or partial replacement of cellulose fibers in paper and containing, at least on the outer surface, one or more nitrogen-containing polymer compounds selected from substances with the following formula: where p is a number with value zero or 1, A-p B and Ag can have different meanings depending on the value of p, and more specifically: when p = 1, A-^ ■ and Ag independently denote groups of the type: •or also, but only when B is different from a pipe.razin radical, groups of- the type , while B can denote a nitrogen radical of the type (piperazinic), or when p = 0, A-^ can denote a group with. or and B have the same meaning.as A^ or denotes a ■group with formula: where in the latter case the molar ratio A^/ B is between 1:20 and h;l and where further: R = H, an aliphatic radical of 1 to 20 carbon atoms or et cycloaliphatic or aromatic radical with 6 to 10 carbon atoms. D = nitrogen group with 1 to k C atoms, Ry. H or - CH^ , 'X - an alkylene group with 1 to 20 C atoms where 1 or more hydrogen atoms may be substituted by hydroxyl, alkyl, amine or alkylamine, or X may be a radical of the type: where m = an integer between 0 and k .(inclusive) • y = an integer between 1 and 3 z an integer between 1 and 20 n = an integer between 5 and 100 when p = 1 and between 5 and 1000 when p = 0, .where B and D independently of each other are nitrogen radicals of K = an alkylene group with 1-6 C atoms,- R = H,- an alkylene group with 1 - 20 C atoms or a cycloali-- phatic or aromatic radical with 6 - 10 C atoms, Rg= an alkyl group with 1-3 C atoms, m = an integer between 5 and 500, where: B and D independently of each other are nitrogen radicals of K = an alkyl group' with 1-6 C atoms, R = H, an aliphatic radical with 1-6 C atoms or a cycloaliphatic or aromatic radical with 6-10 C atoms, •Rg^ an alkyl radical with 1-3 C atoms m = an integer between 0 and 2, n = an integer between 5 and 500, Where: R^ = an' alkyl group with 1 to h C atoms, n is an integer. between 10 and 300, which fibers are characterized by the fact that they have a surface area of more than 1 m 2 /g and by the fact that at least part of the nitrogen compound that is bound on the surface cannot be removed in amounts above 100 ppm per hour male treatment in Lorentz-Wettres-Dutch under refining conditions in accordance with TAPPI standard T - 200 os. 70, under zero load. 2. Fibers as specified in claim 1, characterized in that the nitrogen-containing polymer compounds which are on the surface of the fibers and cannot be removed by said treatment make up 0.5 to 10% by weight of the total weight of fibers and nitrogen compound. 3. Fibers as specified in claim 1 or 2, characterized in that the olefin polymer can be a HD or LD polyethylene, polypropylene with predominantly isotactic macromolecules, poly-3-methyl-pentene-1 or an ethylene-propylene copolymer of statistical type or as block polymer... 1+. Paper or similar product which is wholly or partly made up of fibers according to requirements 1 to 3. 5. Process for the production of fibers as specified in claim 1, characterized in that one extrudes again through an opening and under conditions where there is a practically instantaneous evaporation of the liquid phase out of the extrusion space, either a solution, emulsion, dispersion or suspension of an olefin polymer in one or more liquid media such as ■contains at least 0.5% by weight based on the total weight of the polyolefin, of one or more nitrogen-containing polymer compounds that fall under one or more of the general formulas (I)-(IV) 1 according to requirement 1.." 6. Method as stated in claim 5, characterized in that the nitrogen-containing polymer compounds are found in said solution, emulsion, dispersion or suspension in amounts of between 0.5 and 10% by weight of the total weight of polyolefin plus nitrogen compound. 7. Fibers as specified in claims 1 to 3. characterized in that at least part of the macromolecules which form the nitrogen compounds on the surface of said fibers are chemically bound through one or more of the basic nitrogen atoms to carboxylic acid residues in a polyacid selected from: polyacrylic acid, polymethacrylic acid, polyitaconitic acid and alginic acids. 8. Paper or similar products containing fibers according to claim 7. 9. Paper or similar products containing mixtures of fibers as specified in claim 7 and cellulose fibers.