GB1577635A - Polymer blend - Google Patents

Abstract

Hydrophilic polyolefin fibres are mfd. by mixing a fibrous polyolefin compsn. obtd. by projection by discharge, and contg. a carboxylic function, with an aq. dil. mixt. of water sol. anionic and cationic polymers contg. N. - The cationic polymer is the reaction prod. of epichlorohydrin and (a) an amino-polyamide derived from a dicarboxylic acid and a polyalkylene-polyamide contg. two primary amino gps. and >=1 sec. or tert. amino gp. or (b) a polyalkylene-polyamine of formula H2N(CnH2nNH)xH (I) (where n is a whole no. 2-8; x is a whole no. >=2, or (c) a poly(dialkylamine) or (d) a poly-amino-urylene derived from urea and a polyamine contg. >=3 amino gps. >=1 of which is tert. - The anionic polymer is the reaction prod. of glyoxal and (a) a polyacrylamide contg. 2-15% acrylic acid units, or (b) a branched, partially hydrolysed poly(beta-alanine) contg. 1-10 mol. % carboxyl gps. w.r.t. recurring amide units. The wt. ratio between the cationic polymer and the anionic polymer is 1:3-7. - The fibres are readily dispersible in water and can be admixed with wood pulp fibres to form a pulp which can be conferted into high quality paper with increased tensile strength as compared with a paper prepared without the polymer component.

Description

(54) POLYMER BLEND (71) We, HERCULES INCORPORATED, a Corporation organised under the laws of the State of Delaware, United States of America, of 910 Market Street, City of Wilmington, State of Delaware, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a blend of certain water-soluble, nitrogen-containing polymers, one of which is cationic and the other of which is anionic, useful in the treatment of polyolefin-based fibers containing carboxylic functionality according to a process which is the subject of our Patent Application 3363/77 (Serial No.

1,577,634).

The object of the invention described in that specification is to prepare paper having improved strength properties from blends of polyolefin pulps and wood pulp, and that invention provides a process for the preparation of hydrophilic polyolefin fibers comprising intimately contacting a spurted fibrous polyolefin or composition thereof containing carboxylic functionality with an aqueous, normally dilute, admixture of certain water-soluble nitrogen-containing cationic and Ia nionic polymers. Among said polymers are those of the present invention.

According to the present invention we provide a blend of cationic and anionic water-soluble, nitrogen-containing polymers wherein the cationic polymer is the reaction product of epichlorohydrin and the amino-polyamide derived from adipic acid and diethylenetriamine and wherein the anionic polymer is the reaction product of glyoxal and the polyacrylamide obtained by copolymerization of acrylamide with acrylic acid, the ratio of said cationic polymer to said anionic polymer being in the range of from 1:3 to 1:7 by weight.

The amount of acrylic acid units in the polyacrylamide may be from 2 to 15 percent. The reaction with glyoxal is carried out in a dilute neutral or slightly alkaline aqueous solution of the polymer at a temperature of from 10 to SOOC, preferably from 200 to 300 C. The amount of glyoxal used in the reaction mixture may be from 10 to 100 mole percent, preferably from 20 to 30 mole percent, based on the amide repeat units in the polymer. The resulting solutions possess good stability.

The use of such a blend of cationic and anionic polymers in the abovementioned treatment of fibers is exemplified as follows. Polypropylene and an ethyleneacrylic acid copolymer are dispersed in a solvent such as methylene chloride, and the dispersion is heated in a closed system to a temperature of about 1900C to dissolve the polymer components in the solvent. Under these conditions, the pressure generated by the methylene chloride vapors is of the order of 600 p.s.i.

After introducing nitrogen to increase the vapor pressure of the system to a pressure of about 1000 p.s.i., the resulting solution is vented to the atmosphere through an orifice, resulting in evaporation of the methylene chloride solvent and formation of a fiber product. The fiber product then is suspended in an aqueous medium formed by blending a dilute aqueous solution of epichlorohydrin-modified poly(diethylene-triamine-adipic acid) with a dilute aqueous solution of glyoxalmodified poly(acrylamide-co-acrylic acid), and the components of the resulting suspension are brought into intimate contact with each other, as by refining in a dise refiner. The treated fibers may then be isolated and stored in wet cake form. or the suspension containing the fibers may be used directly in a papermaking process.

The following Examples are given for the purpose of illustrating the invention.

Examples A and B describe the preparation of cationic and anionic polymers respectively, as components to form the blend of the present invention. Examples I to 9 describe the blends and their use in the treatment of polyolefin-based fibers.

Further illustration of the use of these blends and comparisons with other blends of cationic and anionic polymers, will be found in Example 11 to 19 of the parent Specification 3363/77 (Serial No. 1,577,634).

EXAMPLE A A cationic, water-soluble, nitrogen-containing polymer was prepared from diethylenetriamine, adipic acid and epichlorohydrin. Diethylenetriamine in the amount of 0.97 mole was added to a reaction vessel equipped with a mechanical stirrer, a thermometer and a reflux condenser. There was then gradually added to the reaction vessel one mole of adipic acid with stirring. After the acid had dissolved in the amine, the reaction mixture was heated to 170--1750C and held at that temperature for one and one-half hours, by which time the reaction mixture had become very viscous. The reaction mixture then was cooled to 140"C., and sufficient water was added to provide the resulting polyamide solution with a solids content of about 50 percent. A sample of the polyamide isolated from this solution was found to have a reduced specific viscosity of 0.155 deciliters per gram when measured at a concentration of two percent in a one molar aqueous solution of ammonium chloride. The polyamide solution was diluted to 13.5 percent solids and heated to 400C., and epichlorohydrin was slowly added in an amount corresponding to 1.32 moles per mole of secondary amine in the polyamide. The reaction mixture then was heated at a temperature between 70" and 75"C until it attained a Gardner viscosity of E-F. Sufficient water was next added to provide a solids content of about 12.5 percent, and the solution was cooled to 250 C. The pH of the solution then was adjusted to 4.7 with concentrated sulfuric acid. The final product contained 12.5 percent solids and had a Gardner viscosity of B-C.

EXAMPLE B An anionic, water-soluble, nitrogen-containing polymer was prepared from acrylamide, acrylic acid and glyoxal. To a reaction vessel equipped with a mechanical stirrer, a thermometer, a reflux condenser and a nitrogen adapter there was added 890 parts of water. There was then dissolved in the water 98 parts of acrylamide, two parts of acrylic acid and one and one-half parts of aqueous 10 percent cupric sulfate. The resulting solution was sparged with nitrogen and heated to 760C., at which point two parts of ammonium persulfate dissolved in six and onehalf parts of water was added. The temperature of the reaction mixture increased 21.5"C over a period of three minutes following addition of the persulfate. When the temperature returned to 760C., it was maintained there for two hours, after which the reaction mixture was cooled to room temperature. The resulting solution had a Brookfield viscosity of 54 centipoises at 210C and contained less than 0.2 percent 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 mole, of amide repeat units) was added 39.1 parts of aqueous 40 percent glyoxal (15.64 parts, or 0.255 equivalent based on amide repeat units, of glyoxal). The pH of the resulting solution was adjusted to 9.25 by the addition of 111.3 parts of aqueous 2 percent sodium hydroxide. Within approximately 20 minutes after addition of the sodium hydroxide, 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 about two and six-tenths parts of aqueous 40 percent sulfuric acid. The resulting solution had a pH of 4.4 and contained 2.2 percent solids.

EXAMPLE 1 Ninety parts of isotactic polypropylene having an intrinsic viscosity of 2.1 in decahydronaphthalene at 1 350C and 10 parts of an ethylene-acrylic acid copolymer (Dow, 92:8 ethylene:acrylic acid, melt index 5.3) were charged to a closed autoclave along with 400 parts of methylene chloride as the solvent. The contents of the autoclave were stirred and heated to 2200 C., at which point the vapor pressure in the autoclave was raised to 1000 p.s.i. by the introduction of nitrogen.

The resulting solution was spurted from the autoclave into the atmosphere through an orifice having a diameter of one millimeter and a length of one millimeter, resulting in evaporation of the methylene chloride solvent and formation of the desired fiber product. This fiber product then was disc refined for six minutes in a Sprout Waldron disc refiner at 0.25 percent consistency in an aqueous medium containing 0.1 percent of a blend of the cationic polymer of Example A and the anionic polymer of Example B, the weight ratio of the cationic polymer to anionic polymer in the resin blend being 1:5. The refined fiber product, after washing with water, contained 8.5 percent of attached resin based on nitrogen analysis.

EXAMPLE 2 The spurted fiber product of Example 1 was disc refined as in that Example except that an aqueous medium containing 0.05 percent of the blend of cationic and anionic polymer was used. The refined fiber product, after washing with water, contained 5.2 percent attached resin based on nitrogen analysis.

EXAMPLE 3 The procedure of Example 1 was duplicated except for use of the following conditions in preparation of the spurted fiber product: 95 parts of the polypropylene, five parts of ethylene-acrylic acid copolymer (Dow, 88:12 ethylene:acrylic acid, melt index 7.0), a mixture of 360 parts of methylene chloride and 40 parts of acetone as the solvent, a temperature of 220"C and a pressure of 1200 p.s.i. The fiber product so obtained, after disc refining as in Example 1, contained 9.0 percent of deposited resin as determined by nitrogen analysis.

EXAMPLE 4 The procedure of Example 1 was again duplicated except for use this time of the following conditions in preparing the spurted fiber product: 90 parts of an isotactic polypropylene having an intrinsic viscosity of 1.3 in decahydronaphthalene at 1350C., 10 parts of ethylene-acrylic acid copolymer (Union Carbide, 94:6 ethylene:acrylic acid), 900 parts of methylene chloride as the solvent, a temperature of 2000 C., and a pressure of 1000 p.s.i. The fiber product from this spurting process then was disc refined as in Example 1, resulting in fibers containing 7.2 percent of attached resin based on nitrogen analysis.

EXAMPLE 5 A spurted fiber product was prepared following the procedure of Example 1 except for use of 80 parts of the polypropylene, 20 parts of the ethylene-acrylic acid copolymer of Example 4, 400 parts of methylene chloride, a temperature of 210 C and a pressure of 1000 p.s.i. The product was disc refined as in Example 1, giving a fiber product containing 6.7 percent of deposited resin based on nitrogen analysis.

EXAMPLES 6 and 7 Repetition of Example 5 was effected under identical conditions except for use of a 1:7 weight ratio of the cationic polymer of Example A to the anionic polymer of Example E in the resin blend in Example 6 and a 1:3 weight ratio of the polymers in Example 7. The resin pick-up in the fiber product of Example 6 was 6.5 percent and was 5.1 percent in the fiber product of Example 7.

EXAMPLE 8 Each of the synthetic pulps prepared as described in Examples 1 to 7 were blended with bleached kraft wood pulp (50:50 RBK:WBK, pH 6.5, 500 Canadian Standard Freeness) in the ratio of 30 percent synthetic pulp to 70 percent wood pulp. Handsheets prepared from the blends were dried and calendered at 500 Ibs/linear inch at 600C. The brightness, opacity, tensile strength and Mullen burst strength of the calendered sheets were determined, and the results are given in Table 1. In the data given in this table, the tensile strength and Mullen burst strength values are expressed as a percentage of the tensile strength and Mullen burst strength of the 100 percent wood pulp control, all being corrected to a 40 pound per ream basis weight.

TABLE I Mullen Tensile Burst Brightness Opacity Strength Strength Example (percent) (percent) (percent) (percent) 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 7 87.5 82.8 79 63 It is apparent from the above data that the process using polymer blends of this invention will provide paper having from about 70 to about 90 percent of the tensile strength and from about 60 to 85 percent of the Mullen burst strength of a paper prepared from 100 percent wood pulp.

EXAMPLE 9 The procedure of Example 1 was followed using 200 parts of crystalline polypropylene grafted with three percent by weight of maleic anhydride, 2672 parts of methylene chloride, a temperature of 200"C and a pressure of 1000 p.s.i. The spurted fiber product was disc refined as in Example 1, resulting in fibers containing 2.7 percent of deposited resin. The refined pulp was blended with wood pulp and handsheets were prepared and evaluated, as in Example 8. The resulting sheets exhibited 82 percent brightness, 80 percent opacity, 67 percent tensile strength and 71 percent Mullen burst strength.

WHAT WE CLAIM IS: 1. A blend of cationic and anionic water-soluble, nitrogen-containing polymers wherein the cationic polymer is the reaction product of epichlorohydrin and the aminopolyamide derived from adipic acid and diethylenetriamine and wherein the anionic polymer is the reaction product of glyoxal and the polyacrylamide obtained by copolymerization of acrylamide with acrylic acid, the ratio of said cationic polymer to said anionic polymer being in the range from 1:3 to 1:7 by weight.

2. A blend according to Claim 1, wherein the polyacrylamide copolymer contains from 2 to 15 percent acrylic acid units.

3. A blend of cationic and anionic polymers according to Claim I substantially as described in the foregoing Examples.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. TABLE I Mullen Tensile Burst Brightness Opacity Strength Strength Example (percent) (percent) (percent) (percent) 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 íó 7 87.5 82.8 79 63 It is apparent from the above data that the process using polymer blends of this invention will provide paper having from about 70 to about 90 percent of the tensile strength and from about 60 to 85 percent of the Mullen burst strength of a paper prepared from 100 percent wood pulp. EXAMPLE 9 The procedure of Example 1 was followed using 200 parts of crystalline polypropylene grafted with three percent by weight of maleic anhydride, 2672 parts of methylene chloride, a temperature of 200"C and a pressure of 1000 p.s.i. The spurted fiber product was disc refined as in Example 1, resulting in fibers containing 2.7 percent of deposited resin. The refined pulp was blended with wood pulp and handsheets were prepared and evaluated, as in Example 8. The resulting sheets exhibited 82 percent brightness, 80 percent opacity, 67 percent tensile strength and 71 percent Mullen burst strength. WHAT WE CLAIM IS:

1. A blend of cationic and anionic water-soluble, nitrogen-containing polymers wherein the cationic polymer is the reaction product of epichlorohydrin and the aminopolyamide derived from adipic acid and diethylenetriamine and wherein the anionic polymer is the reaction product of glyoxal and the polyacrylamide obtained by copolymerization of acrylamide with acrylic acid, the ratio of said cationic polymer to said anionic polymer being in the range from 1:3 to 1:7 by weight.

2. A blend according to Claim 1, wherein the polyacrylamide copolymer contains from 2 to 15 percent acrylic acid units.

3. A blend of cationic and anionic polymers according to Claim I substantially as described in the foregoing Examples.