DK147079B - PROCEDURE FOR THE PREPARATION OF HYDROFILE POLYOLEFIN FIBERS AND PAPER PRODUCTS CONTAINING THESE - Google Patents

Description

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(19) DENMARK

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DIRECTORATE OF

THE PATENT AND TRADEMARK WEEK

(21) Patent Application No: 0367/77 (51) Int.CI.3: D 01 F 11/06 (22) Date of filing: 28 Jan 1977 D 21 H 5/20 (41) Alm. available: 29 Jul 1977 (44) Submitted: 02 Apr 1984 (86) International Application No: - (30) Priority: 28 Jan 1976 US 653188 07sep1976US721133 (71) Applicant: 'HERCULES INCORPORATED; Wilmlngton, US.

(72) Inventor: Terence William 'Rave; US.

(74) Plenipotentiary: Lehmann & Ree Engineering Company (54) Process for the production of hydrophilic polyolefin fibers and paper products containing them

The invention relates to a process for the production of hydrophilic polyolefin fibers in which a flash-spun fibrous polyolefin containing carboxyl functionality is brought into intimate contact with a dilute aqueous mixture of water-soluble, nitrogen-containing cationic and anionic polymers.

The fibers produced by the process of the invention are readily dispersible in water and can be blended with wood pulp fibers, thereby providing a pulp which can be worked up to high quality paper using conventional papermaking techniques.

In recent years, significant efforts have been made to develop fibrous polyolefin pulp materials with hydrophilic proprietary tools. One such method, developed to provide hydrophilic properties, is that described in U.S. Patent No. 3,743,570. According to this patent, large surface area polyolefin fibers are treated with a hydrophilic colloidal polymeric additive composed of a cationic polymer such as melamine-formaldehyde and an anionic polymer such as carboxymethyl cellulose. Another method developed for the production of hydrophilic polyolefin pulp compositions is a process which includes flash spinning of a mixture of the polyolefin and an additive such as a hydrophilic clay or a hydrophilic polymer, e.g. polyvinyl alcohol.

The spinning process used in these preparations is a process in which the polyolefin and hydrophilic additive are dispersed in a liquid which is not solvent for any of the components at their normal boiling points, the resulting dispersion is heated at hyperatmospheric pressure to dissolve the polymer and solvent-soluble additive, then the resulting composition is discharged into a reduced temperature and pressure zone, usually atmospheric pressure, whereby the fiber product is formed.

A major shortcoming of these hydrophilic polyolefin pulp materials has been that, after blending with wood pulp, the resulting paper products have shown considerably less strength than paper made from wood pulp alone. However, some improvement in the strength of paper made from mixtures of polyolefin pulp and wood pulp has been achieved by imparting anionic character to the polyolefin pulp. P.eks. is known from German Publication No. 2,413,922 the preparation of anionic pulp masses by flash spinning of mixtures of polyolefins and copolymers of olefinic compounds with maleic anhydride or acrylic or methacrylic acid. Mixtures of these wood-pulp pulp compositions have provided paper with better tensile strength than paper produced. easily without the polymer component.

The object of the present invention is to provide a process for the production of hydrophilic polyolefin fibers, which Incorporated in pulp of wood fibers provides paper products with better strength properties than the known paper products made from synthetic pulp and wood pulp.

This is achieved by a process of the kind described in the introduction, characterized in that the cationic polymer is the reaction product between epichlorohydrin and (a) an aminopolyamide derived from a dicarboxylic acid and a polyalkylene polyamine having two primary amino groups and at least one secondary or t (tertiary amino group) or (b) a polyalkylene polyamine of the formula H2N ^ CnI2nNR ^ x ^ n ^ 2n ^ 2 '^ where our R is H or CH or (c) a poly (diallyl amine), or (d) a polyaminourylene derived from urea and a polyamine having at least three amino groups, at least one of which is tertiary, that the anionic polymer is the reaction product between glyoxal and (a) ) a polyacrylamide containing from ca. 2 to approx. 15% acrylic acid units or (b) a partially hydrolyzed, branched poly (β-alanine) containing from ca. 1 to approx. 10 mole% of carboxyl groups based on amide repeating units and the ratio of the cationic polymer to the anionic polymer by weight is between 1: 3 and 1: 7.

An embodiment of the process according to the invention is characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is based on polyethylene.

Another embodiment of the process according to the invention is characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is based on polypropylene.

A third embodiment of the process according to the invention is characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is made by flash-spinning a mixture of polypropylene and an anionic polymer containing carboxyl functionality.

A fourth embodiment of the process according to the invention is characterized in that the anionic polymer containing carboxylic functionality is a copolymer of ethylene and acrylic acid.

A fifth embodiment of the process according to the invention is characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is produced by flash-spinning polypropylene and oxidation of the resulting fibers to introduce carboxyl groups into the polypropylene molecule.

A sixth embodiment of the process according to the invention is characterized in that the aminopolyamide is derived from adipic acid and diethylenetriamine.

The invention also relates to a paper product made from a mixture of wood pulp and hydrophilic carboxylic acid-containing polyolefin fibers, which paper product is characterized in that as hydrophilic carboxylic acid-containing polyolefin fibers are used as made by the process according to the invention. Such a paper product has improved whiteness, opacity, smoothness and printability and can be made with low sheet weights compared to conventional filled or unfilled paper.

It is also advantageous that the synthetic pulp compositions of the invention do not necessitate the presence of particular water-soluble additives, such as starch, in the papermaking process as these are made unnecessary by the presence of the cationic polymer component incorporated in the modified fibers produced by the process of the invention. .

In the process of the invention, the anionic polyolefin-containing material containing carboxyl functionality may be a polyolefin-containing carboxyl group which has been introduced into the polymer molecule by grafting the polyolefin with a monomer containing carboxyl functionality or by oxidizing the polyolefin with oxygen or ozone or material or oxygen. in admixture with an anionic polymer containing carboxyl functionality. In either case, the polyolefin may be polyethylene, polypropylene, an ethylene-propylene copolymer or a mixture of these polyolefin materials.

When the anionic polyolefin material is a mixture of a polyolefin and an anionic polymer containing carboxyl functionality, the latter component may be a polyolefin-containing carboxyl group directly linked to the polymer "backbone", a polyolefin inoculated with acrylic acid, methacrylic acid, maleic acid, maleic acid, maleic acid, a copolymer of any of the substances ethylene, propylene, styrene, α-methylstyrene or mixtures thereof with any of the substances acrylic acid, methacrylic acid, maleic anhydride or mixtures of any of these anionic polymer components. Again, the polyolefin, wherever mentioned, may be polyethylene, polypropylene, an ethylene-propylene copolymer or mixtures thereof.

In the aforementioned mixtures of polyolefin and anionic polymer containing carboxyl functionality, the ratio of the former to the latter will preferably be from ca. 95: 5 to approx. 80: 5 by weight and the amount of carboxyl available in the anionic polymer will be from about 3 to approx. 30% by weight. In general, the anionic polyolefin material used in the process of the invention should contain a sufficient amount of carboxyl functionality to provide at least 0.01 and preferably at least about 10%. 0.04 milliequivalents of carboxyl groups per grams of the polyolefin pulp. Furthermore, the amount of carboxyl functionality may be such that up to approx. e% milli equivalent carboxyl group per grams of the polyolefin pulp. A particularly desirable area is from approx. 0.04 to approx. 0.2 mill equivalent gram.

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The dispersing medium used in the fiber forming step of the process of the invention contains an aqueous solvent which, at its normal boiling point, is not a solvent for the polyolefin material used to form the fibers. It may be the methylene chloride indicated in most of the examples or other halogenated hydrocarbons such as chloroform, carbon tetrachloride, methyl chloride, ethyl chloride, trichlorofluoromethane and 1,1,2-trichloro-1,2,2-trifluoroethane. Also aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as butane, pentane, hexane, heptane, octane and their isomers, and alicyclic hydrocarbons such as cyclohexane are useful. Mixtures of these solvents may be used and water may be present if desired to form an emulsion of the polyolefin material. Furthermore, the pressure generated by the solvent vapors may be, and usually will be, increased by an inert gas under pressure such as nitrogen or carbon dioxide.

While practicing the fiber forming process, the concentration of polyolefin material in solution in the solvent will usually be from approx. 5 to approx. 40% by weight, preferably from approx. 10 to approx. 20% by weight. The temperature at which the dispersion of polyolefin material is heated to readily form a solution of matter will depend upon the particular solvent used and must be sufficiently high to cause dissolution of the material. The fiber-forming temperature will generally be between approx. 100 ° and approx. 225 ° C. The pressure on the solution of the polyolefin material can be from approx. 42 to approx. 105 kg / cm (600-1500 p.s.i.), but is preferably between ca. 63 and approx. 84 kg / cm (900-1200 p.s.i.). The aperture through which the solution is extruded must have a diameter of approx. 0.5 to approx. 15 mm, preferably from approx. 1 to approx. 5 mm and the ratio of the length of the opening to its diameter must be from approx. 0.2 to approx. 10th

In the fiber modification step of the process of the invention, the fibers of the fibrous anionic polyolefin material containing carbojyl functionality as mentioned are brought into intimate contact with a dilute aqueous solution or dispersion of a mixture of certain cationic and anionic nitrogen containing polymers. The ratio of cationic to anionic polymer in the mixture is between 1: 3 and 1: 7 by weight. The cationic polymer component of the aforementioned mixture can generally be classified as the reaction product between epichlorohydrin and a polymer containing secondary or tertiary amine groups or both. A representative group of polymers belonging to this class so defined can be exemplified by the cationic polymeric component used in many of the examples, namely the reaction product between epichlorohydrin and the ethylene triamine and adipic acid derived aminopolyamide. Preparation of this product is shown in Example A. However, this group of cationic polymers is more generally the reaction products between epichlorohydrin and an aminopolyamide derived from a carboxylic acid and a polyalkylene polyamine having two primary amine groups and at least one secondary or tertiary amine group all as described in the U.S. Patents Nos. 2,926,116 and 2,926,154.

Another representative group of polymers belonging to the widely defined class of cationic polymers is the group in which the polymers are water-soluble reaction products of epichlorohydrin and a polyalkylene polyamine. The preparation of an example of a product from this group is shown in Example B.

Polyalkylene polyamines which can be reacted with epichlorohydrin have the formula H „N (CH NR) CH „NH0 where R is H or CH ,, n is an integer of 2-8 and x an integer, preferably 1-5. Examples of such polyalkylene polyamines are the polyethylene polyamines, polypropylene polyamines and polybutylene polyamines. Particular examples of these polyalkylene polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, bis (hexamethylene) triamine and dipropylenetriamine. Other polyalkylene polyamines which may be used include methyl bis (3-aminopropyl) amine, methyl bis (2-aminoethyl) amine and 4,7-dimethyl triethylene tetramine. Mixtures of polyalkylene polyamines may be used if desired.

The relative amounts of polyalkylene polyamine and epichlorohydrin used may be varied according to the particular polyalkylene polyamine used. In general, it is preferred that the mole ratio of epichlorohydrin to polyalkylene polyamine is above 1: 1 and below 4.5: 1. In the preparation of water-soluble resin of epichlorohydrin and tetraethylene pentamine, good results are obtained at molar ratios of from approx. 1.4: 1 to 1.94: 1. The reaction temperature is preferably between ca. 40 ° and approx.

60 ° C.

Yet another group of cationic polymers useful in the present invention is the one in which the polymers are reaction products of epichlorohydrin and a poly (diallylamine). The preparation of such a product is shown in Example C. Further products and processes for their preparation are described in the specification of U.S. Patent No. 3,700,623.

The last group of cationic polymers used according to the invention is the one in which the polymers are the reaction products between epichlorohydrin and a polyaminourylene. The preparation of one of these products is given in Example D. Related products and their preparation are described in the specification of U.S. Patent No. 3,240,664.

The anionic polymer component of the aqueous solution or dispersion wherein the fibers of the anionic polyolefin containing carboxyl functionality are modified is illustrated in the Examples. One of these is the reaction product between glyoxal and the polyacrylamide which is obtained by copolymerizing acrylamide with acrylic acid. The preparation of an example of this product is shown in Example E. The amount of acrylic acid units in the copolymer can be from

2 to approx. 15%. Similar products may be prepared by partial hydrolysis of polyacrylamide or by a copolymer of acrylamide and an alkyl acrylate such as a copolymer of acrylamide with ethyl acrylate. Any of these polyacrylamides can be prepared by conventional methods for polymerizing water-soluble monomers, and preferably have a molecular weight of less than about 10%. 25,000, e.g. between approx. 10,000 and approx. 25,000.

The second anionic nitrogen-containing polymer shown in the Examples is the reaction product between glyoxal and the polymer produced by partial hydrolysis of a branched, water-soluble poly (β-alanine). Preparation of a representative product is shown in Example F. The poly (β-alariin) is prepared by the anionic polymerization of acrylamide in the presence of a basic catalyst such as sodium hydroxide and a vinyl or free radical polymerization inhibitor such as phenyl-β-naphthylamine. and the polymer will have a molecular weight of between approx. 500 and approx. 10,000, preferably from ca. 2,000 to approx. 6000. Due to the extremely exothermic nature of the anionic polymerization, it is preferred to carry out the reaction in a suitable organic reaction medium such as toluene or chlorobenzene which is inert at the reaction conditions and is capable of dissolving or suspending acrylamide.

The branched poly (β-alanine) prepared as described above is a neutral polymer and must be anionically modified for the purposes of the present invention. Anionic modification of branched poly (β-alanine) can be accomplished by partial hydrolysis of the polymer to convert some of the primary amide groups to anionic carboxyl groups. Eg. For example, hydrolysis of poly (β-alanine) can take place by heating a slightly alkaline aqueous solution of the polymer having a pH of approx. 9-10 at temperatures of approx. 50 to approx. 100 ° C. The amount of anionic groups introduced must be from about, one to about ten mole percent and preferably from ca. two to about five mole percent based on amide repeat units.

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Each of the anionic nitrogen-containing polymers described above is modified with glyoxal to provide the desired anionic, water-soluble, nitrogen-containing polymers used in the present invention. The reaction with glyoxal is carried out in a dilute neutral or slightly alkaline aqueous solution of the polymer at a temperature of from ca. 10 to approx. 50 ° C, preferably from ca. 20 to approx. 30 ° C. The amount of glyoxal used in the reaction mixture can be from about 10 to approx. 100 mole percent, preferably from ca. 20 to approx. 30 mole percent based on amide repeat units in the polymer. The resulting solutions possess good stability.

The process of the invention enables the production of improved paper products from blends of wood pulp and polyolefin pulp pulp. The process is contingent upon the particular combination of cationic and anionic nitrogen-containing polymers used in the fiber modification step, and the latter preferably includes the use of a refining procedure such as disc refining. Furthermore, the process depends on certain critical factors, namely the presence of at least 80% polyolefin in the polyolefin carboxyl-containing anionic polymer admixture, when this admixture constitutes the anionic polyolefin material containing carboxyl functionality / polyphosphine content of a limit viscosity number of 1.0 at 135 ° C in the decahydronaphthalene, sufficiently available carboxyl in the anionic polyolefin material containing carboxyl functionality and sufficient resin in the aqueous solution or dispersion in which the anionic fibers are modified. Operation within the limits of these conditions makes it possible to produce a synthetic pulp which, when mixed with wood pulp, will provide a paper product with at least 70% of 100% wood pulp tensile strength, as well as increased whiteness, opacity and smoothness.

As an example of the process of the invention, polypropylene and an ethylene-acrylic acid copolymer are dispersed in a solvent such as methylene chloride, and the dispersion is heated in an enclosed system to a temperature of approx. 190 C to dissolve the polymer components in the solvent. Under these conditions, the pressure generated by the methylene chloride vapors is of the order of 2 42.2 kg / cm (600 p.s.i.). After introducing nitrogen to increase 2 of the system vapor pressure to a pressure of approx. 70.3 kg / cm (1000 p.s.i.), the resulting solution is delivered to the atmosphere through an orifice, which results in evaporation of the methylene chloride solvent and formation of the fiber product. The fiber product is then suspended in an aqueous medium provided by mixing a dilute aqueous solution of e.g. epichlorohydrin modified poly (diethylenetriamine adipic acid) with a dilute aqueous solution of e.g. glyoxal-modified poly (acrylamide acrylic acid), and the components of the resulting suspension are brought into intimate contact with one another, such as by refining in a disc refiner. The treated fibers can then be isolated and stored in the form of wet cakes, or the fiber-containing suspension can be used directly in a papermaking process.

While the embodiments of the invention have been outlined generally above, the examples below are special illustrations. All quantity declarations are by weight.

EXAMPLE A

A cationic, water-soluble, nitrogen-containing polymer was prepared from diethylenetriamine, adipic acid and epichlorohydrin. Diethylene triamine in the amount of 0.97 mol was added to a reaction vessel equipped with a mechanical stirrer, a thermometer and a reflux condenser. Then a mole of adipic acid was gradually added with stirring. After the acid was dissolved in the amine, the reaction mixture was heated to 170-175 ° C and kept at that temperature for one and a half hours, at which time the reaction mixture became very viscous. The reaction mixture was then cooled to 140 ° C and enough water was added to give the resulting polyamide solution a dry matter content of approx. 50%. A sample of the polyamide isolated from this solution was found to have a viscosity of 0.155 dl / g as measured with an Ubbelohde viscometer at a concentration of 2% in a one-molar aqueous solution of ammonium chloride. The polyamide solution was diluted to 13.5% solids and heated to 40 ° C, and epichlorohydrin was added slowly in an amount equal to 1.32 moles per ml. moles of secondary amine in the polyamide. The reaction mixture was then heated to a temperature between 70 ° and 75 ° C until it reached a Gardner viscosity of E-F. Then enough water was added to give a dry matter content of approx. 12.5% and the solution cooled to 25 ° C. The pH of the solution was then adjusted to 4.7 with concentrated sulfuric acid. The final product contained 12.5% solids and had a Gardner viscosity of B-C.

EXAMPLE B

Another representative cationic, water-soluble, nitrogen-containing polymer was prepared, this time using epichlorohydrin and a commercially available aqueous mixture of polyamines as the reactants. This mixture contained at least 75% bis (hexamethylene) triamine and higher homologue, while the remainder of the mixture consisted of lower molecular weight amines, nitriles and lactams. The reaction was carried out in a boiler equipped with a steam jet vacuum system which was used to extract vapors through a condenser rather than allowing them to evade through an opening in the boiler.

The boiler was filled with 704 parts of water and 476 parts of epichlorohydrin, and then 420 parts of the commercial mixture of polyamines were added to the boiler over a period of 35 minutes, cooling the reaction mixture to prevent the temperature from exceeding 70 ° C. After addition of the amine, six parts of aqueous 20% sodium hydroxide were added to speed the reaction, and after a total of 160 minutes at ca. At 70 ° C, the reaction mixture was diluted with 640 parts of water to reduce the viscosity to a Gardner value of approx. C. A total of 44 parts of aqueous 20% sodium hydroxide was then added over a period of 105 minutes. A Gardner viscosity of S was reached after 215 minutes, at which time the reaction was terminated by the addition of 26 parts of concentrated sulfuric acid dissolved in 1345 parts of water. The resulting solution had a Gardner viscosity of D, and additional sulfuric acid and water were added to adjust the pH to 4 and give a dry matter content of 22.5%.

EXAMPLE C

A further cationic, water-soluble, nitrogen-containing polymer was prepared, wherein the basic reactants were methyldiallylamine and epichlorohydrin. To 333 parts of methyldiallylamine, 290-295 parts of concentrated hydrochloric acid were slowly added to provide a solution having a pH of 3-4. The solution was then bubbled with nitrogen for 20 minutes and the temperature adjusted to 50-60 ° C. An aqueous 10.7% solution of sodium bisulfite and an aqueous 10.1% solution of t-butyl hydroperoxide were simultaneously added to the reaction mixture over a period of 4-5 hours until the resulting polymer, poly (methyl-diallylamine hydrochloride) had a viscosity number of 0.2 dl / g measured with an Ub dissolved viscometer on a 1% solution in aqueous average sodium chloride at 25 ° C. In both cases, the amount of sodium bisulfite and t-butyl hydroperoxide used was two mole percent based on the polymer repeating units.

To the above polymer solution, 600 parts of aqueous 4% sodium hydroxide were then added and the temperature of the resulting solution was adjusted to 35 ° C. After adding enough water to reduce the polymer solids content to 22%, 416.3 parts of epichlorohydrin was added. The temperature of the reaction mixture was maintained at ca. 45 ° C, while the Gardner viscosity of the mixture increased from less than A to B +. After the addition of 304 parts of 36% hydrochloric acid, the reaction mixture was heated to 80 ° C and kept at this temperature with continuous addition of additional amounts of hydrochloric acid until the pH of the reaction mixture stabilized at 2 for one hour. The reaction mixture was then cooled to 40 ° C, the pH was adjusted to 3.5-4.0 with aqueous 4% sodium hydroxide and diluted to 20% dry matter.

The resin product of the above process must be base activated before use according to the invention. This is accomplished by adding 18 parts of water and 12 parts of one molar sodium hydroxide solution to each 10 parts of the solution of the resin with 20% solids. The resulting solution with 5% solids should, after ripening for 15 minutes, have a pH of 10 or more. Additional sodium hydroxide must be added if necessary to achieve this pH level.

EXAMPLE D

Another useful cationic, water-soluble, nitrogen-containing polymer was prepared from bis (3-aminopropyl) methylamine, urea and epichlorohydrin. 210 parts of the amine and 87 parts of urea were placed in a reaction vessel, heated: to-175 ° C, kept at this temperature for one hour and then cooled to 155 ° C. Water was added to the reaction product in an amount of 375 parts and the resulting solution was cooled to room temperature.

To 271 parts of the above solution were added 321 parts of water, 29 parts of concentrated hydrochloric acid and 89.6 parts of epichlorohydrin. The temperature of the reaction mixture was kept between 39 ° and 42 ° C for approx. 85 minutes, while the Gardner viscosity of the mixture increased from A-B to L +.

Partially concentrated hydrochloric acid was added to the mixture and the resulting mixture was heated to a temperature between 60 and 75 ° C for four hours, an hour and a half, nine parts of hydrochloric acid was added to keep the pH below 2. The mixture was then cooled to room temperature. The resulting epichlorohydrin modified polyaminurylene product contained 27% solids.

The above product must also be activated before use according to the invention. Activation is accomplished by adding 10 parts of the above product to 10 parts of one molar sodium hydroxide solution, ripening the resulting solution for 15 minutes and then diluting the solution (13.5% dry matter) to 5% dry matter or less before use.

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EXAMPLE E

An anionic, water-soluble, nitrogen-containing polymer was prepared from acrylamide, acrylic acid and glyoxal. 890 parts of water were added to a reaction vessel equipped with a mechanical stirrer, thermometer, reflux condenser and nitrogen supply. Then 98 parts of acrylamide, two parts of acrylic acid and one and a half parts of aqueous 10% cuprous sulfate were dissolved in the water. The resulting solution was bubbled with nitrogen and heated to 76 ° C, at which time two parts of ammonium persulfate dissolved in six and a half parts of water were added. The temperature of the reaction mixture increased 21.5 ° C over a period of three minutes after the addition of persulphate. When the temperature reached 76 ° C, it was kept there for two hours, after which the reaction mixture was cooled to room temperature. The resulting solution had a Brookfield viscosity of 54 centipoise at 21 ° C and contained less than 0.2% acrylamide based on the polymer content.

To 766.9 parts of the above solution (76.7 parts of polymer containing 75.2 parts or 1.06 moles of amide repeat units), 39.1 parts of aqueous 40% glyoxal (15.64 parts or 0.255 equivalent based on amide repeat units glyoxal) were added. The pH of the resulting solution was adjusted to 9.25 by the addition of 111.3 parts of aqueous 2% sodium hydroxide. Over approx. 20 minutes after the sodium hydroxide addition, the Gardner viscosity of the solution had increased from A to E. The reaction was then terminated by the addition of 2777 parts of water and ca. 2.6 parts aqueous 40% sulfuric acid. The resulting solution had a pH of 4.4 and contained 2.2% solids.

EXAMPLE F

Another example of an anionic, water-soluble, nitrogen-containing polymer was prepared using acrylamide and glyoxal alone as reactants. Into a reaction vessel equipped with a stirrer, thermometer and reflux was placed 350 parts of acrylamide, one part of phenyl-3-naphthylamine and 3870 parts of chlorobenzene. This mixture was heated to 80-90 ° C with vigorous stirring to partially melt and partially dissolve the acrylamide.

Some sodium hydroxide flakes were then added to the mixture and after an induction period an exothermic reaction occurred and polymer was separated on the stirrer and on the walls of the reaction vessel. Another three portions consisting of some sodium hydroxide flakes were added to the reaction mixture at thirty minute intervals, after which the reaction mixture was heated to ca. 90 ° C for one hour. The hot chlorobenzene was then decanted and the residual dry substance, a branched, 13 U 7079 water-soluble poly (β-alanine) was washed three times with acetone and then dissolved at room temperature in 1000 parts of water. The cloudy solution thus obtained having a pH of approx. 10.5 was heated to ca. 75 ° C for approx. 30 minutes to achieve partial hydrolysis of the amide groups in the poly (β-alanine) and vapor is blown through the solution until the residual chlorobenzene has been removed and the last trace of polymer dissolved. After cooling, the pH of the solution was adjusted to ca.

5.5 with sulfuric acid. The dissolved polymer contained approx. 2 mole percent carboxyl groups as determined by potentiometric titration.

To an aqueous 15% solution of the above polymer, an aqueous 40% solution of glyoxal was added in sufficient quantity to give 25 mole percent glyoxal based on the amide repeat units in the polymer. The pH of the resulting solution was slowly raised to approx. 9.0-9.5 at room temperature by the addition of dilute aqueous sodium hydroxide, and the pH was maintained at this level until an increase in Gardner viscosity of 5-6 units occurred. The solution was then rapidly diluted with water to 10% total solids and adjusted to a pH of 5.0 with sulfuric acid.

Example 1 90 parts of isotactic polypropylene having an intrinsic viscosity number [η] of 2.1 dl / g as measured with a Ubbelohde viscometer in decahydronaphthalene at 135 ° C and 10 parts of an ethylene-acrylic copolymer (Dow, 92: 8 ethylene: acrylic acid, melting point 5.3) was placed in a closed autoclave together with 400 parts of methylene chloride as solvent.

The contents of the autoclave were stirred and heated to 220 ° C, at which time the steam pressure of the autoclave was raised to 70.3 kg / cm (1000 p.s.i.) by the addition of nitrogen. The resulting solution was discharged from the autoclave into the atmosphere through an opening of 1 mm diameter and 1 mm length, resulting in evaporation of the methylene chloride solvent and formation of the desired fiber product. This fiber product was then sliced for 6 minutes in a Sprout Waldron slice refiner at 0.25% dust density in an aqueous medium containing 0.1% of a mixture of the cationic polymer of Example A and the anionic polymer of Example E, the weight ratio of the cationic polymer and the anionic polymer in the resin mixture were 1: 5. The purified fiber product, after washing with water, contained 8.5% associated resin based on nitrogen analysis.

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Example 2

The flash-spun fiber product of Example 1 was sliced as in this example except that an aqueous medium containing 0.05% of the mixture of cationic and anionic polymers was used. The purified fiber product, after washing with water, contained 5.2% of resin based on nitrogen analysis.

Example 3

The procedure of Example 1 was repeated except that the following conditions were used in the preparation of the spun fiber product: 95 parts of the polypropylene, five parts of ethylene-acrylic acid copolymer (Dow, 88:12 ethylene: acrylic acid, melting point 7.0), a mixture of 360 parts of methylene chloride and 40 parts of acetone as solvent, a temperature of 220 ° C and a pressure of 84.4 kg / cm 2 (1200 psi). The fiber product thus obtained, after disc refining, contained, as in Example 1, 9.0% resin deposited, as determined by nitrogen analysis.

Example 4

The procedure of Example 1 was repeated again except that this time the following conditions were used in the preparation of the flash spun fiber product: 90 parts of isotactic polypropylene having an intrinsic viscosity number [η] of 1.3 dl / g measured with an Ub dissolved viscometer in decahydronaphthalene at 135 ° C, 10 parts of ethylene-acrylic acid copolymer (Union Carbide, 94: 6 ethylene: acrylic acid), 900 parts of methylene chloride as solvent, a temperature of 200 ° C and a pressure of 70.3 kg / cm (1000 psi). The fiber product from this spinning process was then sliced as in Example 1 to yield fibers containing 7.2% associated with resin based on nitrogen analysis.

Example 5

A flash spun fiber product was prepared according to the procedure of Example 1 except that 80 parts of the polypropylene and 20 parts of the ethylene-acrylic acid copolymer of Example 4 were used, 400 parts of methylene chloride, a temperature of 210 ° C and a pressure of 70.3 kg / day. cm (1000 psi). The product was sliced refined as in Example 1 to give a fiber product containing 6.7% of resin deposited based on nitrogen analysis.

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Examples 6 and 7

Repeat Example 5 was carried out under the same conditions except that a 1: 7 weight ratio was used between the cationic polymer of Example A and the anionic polymer of Example E in the resin mixture of Example 6 and a weight ratio of 1: 3 between the polymers of Example 7. The resin uptake in the fiber product of Example 6 was 6.5% and in the fiber product of Example 7 5.1%.

Example 8

Each of the synthetic pulp compositions prepared as described in Examples 1-7 was mixed with bleached kraft wood pulp (50:50 RBK: WBK, pH 6.5, 500 Canadian Standard Freeness) in the ratio of 30% synthetic pulp to 70% wood pulp. Hand sheets made from the mixtures were dried and calendered at 89 kg / cm (500 lbs / linear inch) at 60 ° C. The whiteness, opacity, tensile strength and Mullen fracture strength of the calendered sheets were determined and the results are given in Table 1. In the data given in this table, tensile strength and Mullen tensile strength values expressed as a percentage of tensile strength and Mullen fracture strength of the comparison sample consisted of 100% wood pulp, where all results are corrected to a basis weight of 18.1 kg per rice.

Table 1

Example Whiteness visibility Trek Turkey Mullen fracture Turkey (%) (%) (%) (%) 1 87.3 85.8 90 86 2 87.9 87.2 82 84 3 87.6 87.7 78 78 4 84 , 4 81.5 71 68 5 87.2 82.5 78 72 6 87.4 81.8 76 76 7 87.5 82.8 79 63

It is apparent from the above data that the method according to the invention will provide paper with a tensile strength of from approx. 70 to approx. 90% of the tensile strength and from approx. 60 to approx. 85% of the Mullen breaking strength of paper made from 100% wood pulp.

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Example 9

The procedure of Example 1 was followed using 200 parts of crystalline polypropylene seeded with three parts by weight of maleic anhydride, 2672 parts of methylene chloride, a temperature of 200 ° C and a pressure of 70.3 kg / cm 2 (1000 p.s.i.). the flash-spun fiber product sliced refine was prepared as in Example 1 to yield fibers containing 2.7% resin deposited. The refined pulp was mixed with wood pulp and hand sheets were prepared and evaluated as in Example 8. The resulting sheets had a whiteness of 82%, an opacity of 80%, a tensile strength of 67% and a Mullen breaking strength of 71%.

Example 10

The procedure of Example 1 was used to prepare a flash spun fiber product of crystalline polypropylene seeded with six weight percent acrylic acid. Water: hexane was used as the dispersion medium in the 3: 2 weight ratio. The fiber product was sliced refined as in Example 1 except that an aqueous 0.5% solution of a mixture of the cationic polymer of Example A with the anionic polymer of Example F was used, the weight ratio of the cationic polymer to the anionic polymer being 1 : 3rd The amount of resin deposited on the fibers was 7.2%. The purified pulp was mixed with wood pulp and hand sheets were prepared and evaluated as in Example 8. The resulting sheets showed a whiteness of 87%, an opacity of 79.3% and a tensile strength of 77%.

Example 11

Ninety parts h.d. polyethylene (DuPont, melting point 5.5-6.5 at 190 ° C) replaced the polypropylene in Example 1, and the mixture with the ethylene-acrylic acid copolymer flash-flashed from solution in methylene chloride at 200 ° C and a pressure of 70.3 kg / cm 2 (1000 psi), the fiber product was sliced as in Example 1, and the purified pulp was mixed with wood pulp and hand sheets were prepared and evaluated as in Example 8. The resulting sheets exhibited a whiteness of 84%, an opacity of 80%, and tensile strength of 68 % and a Mullen breaking strength of 69%.

Example 12 130 parts of polypropylene having an intrinsic viscosity [η] of 2.2 dl / g as measured with a Ubbelohde viscometer in the decahydronaphthalene at 135 ° C, 870 parts of methylene chloride, a temperature of 222 ° C and a 2 pressure of 70.3 kg / cm was used in the preparation of a fiber product according to the procedure of Example 1. 60 parts of the fiber product 17 were suspended in 6000 parts of water, the resulting suspension was stirred, 3 3 and air containing 24.7 g / m (0.7 g / ft) ozone. was passed through the suspension at room temperature in an amount of 1.7 l / min (0.06 ft / min) for a period of 15 minutes. Under these conditions, the ozone uptake of the fiber was 0.53% by weight of the fibers and the fibers had an acid number corresponding to 0.033 milliequivalents of carboxyl groups per minute. grams of fiber. The wet ozonized fibers were disc refined as in Example 1, and the refined product was found to contain 5.4% associated resin based on nitrogen analysis. The refined pulp was then mixed with wood pulp (50:50 RBK: WBK, 750 Canadian Standard Freeness) and hand sheets were prepared and evaluated as in Example 8. The resulting sheets exhibited a whiteness of 87.3%, an opacity of 87.6% and a tensile strength of 84%.

Example 13

The procedure of Example 12 was repeated except that the ozonization reaction proceeded over one hour. The ozone uptake of the fibers was 1.9% and the fibers had an acid number equal to 0.129 milliequivalents of carboxyl groups per minute. grams of fiber. After disc refining, the fibers contained 5.1% of resin and the hand sheets made according to Example 8 exhibited a whiteness of 87.2%, an opacity of 87.7% and a tensile strength of 89%.

Example 14

The procedure of Example 13 was repeated except that h.d. polyethylene instead of polypropylene, and that pentane was used as a solvent instead of methylene chloride. Ozone uptake was 1.2%, the acid number was 0.115 milliequivalents per day. grams, the amount of bonded resin was 8.8% and the hand sheets exhibited a whiteness of 85%, an opacity of 87% and a tensile strength of 100%.

Example 15

Following the technique of Example 12 in general, a flash-spun fiber product of h.d. polyethylene grafted with 5% maleic anhydride, a one percent suspension of 60 parts of the fibers was prepared in water, and ozone was passed through the fiber suspension for one hour at 25 ° C at a rate of 0.039 g / minute. The ozonized fibers were slice refined at a dust density of 0.125% in an aqueous medium containing 0.05% of the resin blend of Example 1. The resin uptake from the refining procedure was 5.4% and after blending with wood pulp and forming hand sheets as in Example 8, the resulting sheets exhibited a whiteness of 87.5%, an opacity of 85% and a tensile strength of 85%.

Example 16

A polypropylene fiber product was prepared using conditions similar to those of Example 12. Part of this product was blended with five weight percent wood pulp (50:50 RBK: WBK) based on polypropylene fibers and the fiber blend was sliced until it became water dispersible. A one percent dispersion of the mixture in water was then ozonized by passing ozone through the fiber dispersion at room temperature until the ozonized fibers had an acid number corresponding to 0.07 milliequivalents of carboxyl groups per minute. grams of fiber. Thirty parts of the ozonized pulp were blended with 70 parts of wood pulp, and for portions of the resulting mixture, five percent by weight of the total fiber weight of the (a) resin blend of Example 1 was added in paper-making vessels, (b) a mixture of the cationic polymer of Example B with the anionic polymer of Example E, the weight ratio of cationic to anionic being 1: 5; (c) a mixture of the cationic polymer of Example C with the anionic polymer of Example E, the weight ratio of cationic to anionic being 1: 5; and (d) a mixture of the cationic polymer of Example D with the anionic polymer of Example E, the weight ratio of cationic to anionic being 1: 5. After thorough mixing of the additives with the pulp, hand sheets were prepared and evaluated as described in Example 8. The results are shown in Table 2.

Table 2

Additive Opaque Fabric_ White Lightness_ Tensile Strength (%) (%) (%) (a) 87.8 84.5 67 (b) 87.1 84.3 68 (c) 87.6 84.4 74 (d) 87.8 84.2 69

Comparative data obtained from the evaluation of representative known methods and polymeric additives are shown in the examples below. All quantities are again on a weight basis.

147079 19

Comparative Example 17

Following the procedure of Example 1, a fiber product of 95 parts of polypropylene and five parts of the ethylene-acrylic acid copolymer of this example was prepared, and separate portions of the fiber product were sliced into an aqueous medium containing 0.1% of (a) the resin mixture of Example 1 , (b) a 1: 1 mixture of melamine-formaldehyde polymer (Paramel HE, American Cyanamide) and carboxymethyl cellulose (CMC, DS 0.4, Hercules), and (c) a 2: 1 mixture of Paramel and CMC. polymers. Each of the resulting pulp masses was mixed with wood pulp, and hand sheets were prepared and evaluated as described in Example 8. The results are shown in Table 3.

Table 3

Additive-Transparent-Tensile-White Fabric Strength Strength Strength (S) (%) (S) (%) (a) 82.5 87.0 73.5 56.0 (b) 81.8 86.7 38.2 24.9 (c) 84.3 88.2 44.1 26.0

These data show that replacement of resin blend (a) with known blends (b) and (c) by the process of the invention does not yield a paper of the desired strength.

Comparative Example 18

A flash spun fiber product, substantially identical to the product of Example 1, is disc refined for six minutes in water in a Sprout Waldron disc refiner at a dust density of 0.25%. The refined pulp was blended with bleached kraft wood pulp (50:50 RBK: WBK, 500 Canadian Standard Freeness) as in Example 8, and for portions of the resulting mixture, 5 percent based on the total fiber weight of the (a) resin blend of Example 1 was added 7, (b) a mixture of the cationic polymer of Example B with the anionic polymer of Example E, the weight ratio of the cationic polymer to the anionic polymer being 1: 3, (c) a mixture of the cationic polymer of Example C with the anionic polymer of Example E, the weight ratio of the cationic polymer to the anionic polymer being 1: 3, and (d) the 2: 1 mixture of Paramel and CMC according to 207070

Example 17. Further portions of the pulp mixture were similarly treated with one and a half percent (a), (b), (c) and (d) based on the total fiber weight. Hand sheets were prepared and evaluated as described in Example 8. The results are given in Table 4.

Table 4

Additive Opaque-Tensile-Tissue Whiteness Strength Strength (%) (%) (%) (%) 5.0% (a) 82.5 82.4 87 102 5.0% (b) 81.0 83, 8 75 103 5.0% (c) 81.3 80.3 92 86 5.0% (d) 85.6 82.0 50 52 1.5% (a) 85.1 83.6 67 69 1, 5% (b) 84.6 82.9 70 68 1.5% (c) 84.0 81.6 70 95 1.5% (d) 86.5 83.1 55 40

It can be seen from the above data that the additives (a), (b) and (c) of the invention provide better paper strength than the known additive (d).

Comparative Example 19

A flash spun fiber product was prepared as in Example 1 except that the ethylene-acrylic acid copolymer was omitted and 100 parts of polypropylene was used. Separate portions of the fiber product were treated in a Waring blender in aqueous medium containing 1.0% of (a) the resin mixture of Example 1, (b) the 1: 1 mixture of Paramel and CMC of Example 17 and (c) 2: 1- The mixture of Paramel and CMC according to Example 17. The resulting pulp masses were mixed with wood pulp and hand sheets prepared and evaluated as described in Example 8. Table 5 shows the results obtained.

147079 21

Table 5

Addition-Transparent-Tensile-White Fabric strength strength breaking strength (%) (%) (%) (%) (a) 87.6 87.5 47.7 37.1 (b) 89.6 87.8 36.2 22.9 (c) 89.2 88.2 36.9 26.3

This data again shows the superiority of the additive (a) of the invention over known additives (b) and (c). Furthermore, when compared with Example 17, the results of additive (a) show the importance of the carboxyl functionality of the anionic polyolefin composition used in the process of the invention.

Example 20

Eighty parts of the polypropylene of Examples 1 and 20 parts of polystyrene-maleic anhydride copolymer (Arco, 75:25 styrene: maleic anhydride, molecular weight 19,000) were placed in a closed autoclave together with 250 parts of hexane and 250 parts of water. The contents of the autoclave were stirred and heated to 220 ° C, at which time the vapor pressure in the autoclave was increased to 70.3 kg / cm (1000 p.s.i.) with nitrogen. The resulting solution was stretched from the autoclave to the atmosphere through an orifice having a diameter of one mm and a length of one mm, thereby forming a fiber product.

Portions of the fiber product were disc refined for six minutes in a Sprout Waldron disc refiner at a dust density of 0.25% in (a) water, (b) an aqueous 0.5% solution of the cationic polymer of Example A, (c) an aqueous (D) an aqueous 0.5% solution of melamine-formaldehyde polymer (Paramel HE, American Cyanamide), (e) an aqueous 0.5% solution of a glyoxalite , 5% solution of cationic starch, and (f) an aqueous 0.5% solution of a 1: 3 mixture of the cationic polymer of Example A and the anionic polymer of Example F. Each of the resulting pulp compositions was mixed with wood pulp, and hand sheets were prepared and evaluated as described in Example 8. The data thus obtained are given in Table 6.

22 147079

Table 6

Purification- Opaque- Tensile- Mullen Medium Whitness Strength Strength (%) (%) (%) (%) (a) 84.2 81.3 41 30 (b) 85.2 79.8 51 48 (c) 85.5 81.4 39 32 (d) 81.6 82.5 48 38 (e) 84.8 79.2 54 48 (f) 82.1 79.4 72 71

These data show that when single additives are used in the process of the invention, they are by no means as effective in providing a paper of appropriate strength as a mixture of the specific cationic and anionic polymers of the invention such as that of (f) mixture used.

Claims (6)

23 147079 Patent Claims. A process for preparing hydrophilic polyolefin fibers, in which a flash-spun fibrous polyolefin material containing carboxyl functionality is brought into intimate contact with a dilute aqueous mixture of water-soluble, nitrogen-containing cationic and anionic polymers, characterized in that the cationic polymer is the reaction product ( a) an aminopolyamide derived from a dicarboxylic acid and a polyalkylene polyamine having two primary amino groups and at least one secondary or tertiary amino group, or (b) a polyalkylene polyamine of the formula H, N (CH, NR) CH0, n is an integer of 2-8, and x is an integer, or (c) a poly (diallylamine), or (d) a polyaminourylene derived from urea and a polyamine having at least three amino groups, of which at least one is tertiary, that the anionic polymer is the reaction product between glyoxal and (a) a polyacrylamide containing from ca. 2 to approx. 15% acrylic acid units or (b) a partially hydrolyzed, branched poly (β-alanine) containing from ca. 1 to approx. 10 mole% of carboxyl groups based on amide repeating units and the ratio of the cationic polymer to the anionic polymer by weight is between 1: 3 and 1: 7. Process according to claim 1, characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is based on polyethylene. Process according to claim 1, characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is based on polypropylene. Process according to claim 3, characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is produced by flash-spinning a mixture of polypropylene and an anionic polymer containing carboxyl functionality. Process according to claim 4, characterized in that the anionic polymer containing carboxylic functionality is a copolymer of ethylene and acrylic acid. Process according to claim 3, characterized in that the flash-spun fibrous polyolefin material containing carboxyl functionality is made by flash-spinning polyethylene.