Process for bleaching wood pulp with ozone in the presence of a cationic surfactant

Claim 2

A process for bleaching wood pulp comprising the steps of: (a) mixing a low consistency wood pulp slurry with 0.01% to 1.0% cationic surfactant by weight based on ovendried pulp, said slurry comprising from 0.1% to 10% by weight of ovendried wood pulp and having a pH range from 1 to 7 and, said cationic surfactant having a formula: ##STR2## wherein, R is CH 3 or CH 2 CH 3 , R 1 is an alkyl radical containing from 3 to 15 carbon atoms, an aryl radical, or an alkylaryl radical and X is a halogen; and (b) introducing ozone gas into said wood pulp slurry containing said cationic surfactant for a time effective to bleach said wood pulp.

Claim 3

The process according to claim 1 wherein the pH of said slurry is adjusted to between 2 and 4.

Claim 4

The process according to claim 1 including the further step of: (c) recovering bleached wood pulp having a G.E. brightness value of at least 52.9%.

Claim 5

The process according to claim 1, whereby acid is mixed with said slurry before said cationic surfactant is added to said slurry.

Claim 6

The process according to claim 4 wherein said acid added is selected from the group consisting of sulfuric acid, hydrochloric acid, and acetic acid.

Claim 7

The process according to claim 1 wherein said slurry contains an aqueous acid to decrease the attraction of said cationic surfactant to said wood pulp.

Claim 8

The process according to claim 1 wherein said slurry has a consistency ranging from 1.0% to 5.0% by weight of ovendried pulp.

Claim 9

The process according to claim 7 wherein said cationic surfactant is present in an amount ranging from 0.1% to 0.5% by weight of ovendried pulp.

Claim 10

The process according to claim 1 wherein said cationic surfactant is a member of the group consisting of hexadecyl trimethyl ammonium bromide, nonyl trimethyl ammonium bromide and dodecyl trimethyl ammonium bromide.

Claim 11

The process according to claim 1 wherein said wood pulp is obtained from a Kraft, sulfite or soda pulping process.

Claim 12

The process according to claim 1 wherein said ozone is introduced at a rate sufficient to result in the consumption of from about 0.1 to about 3% ozone based on the weight of the oven dried pulp being treated during the process.

Claim 13

A process for bleaching wood pulp which comprises: (a) mixing an aqueous slurry of wood pulp, at a consistency from 0.1% to 10% by weight of ovendried pulp and having a pH ranging from 2 to 7, with 0.01% to 1.0% cationic surfactant by weight based on ovendried pulp, said cationic surfactant being selected from the group consisting of ##STR3## wherein R is CH 3 or CH 2 CH 3 , R 1 is an alkyl radical containing from 3 to 15 carbon atoms, an aryl radical or an alkylaryl radical and X is a halogen; and (b) bleaching said slurry, containing said cationic surfactant, with ozone at a temperature from room temperature to about 100° C. until from 0.5% to about 3.0% by weight of ozone based upon the weight of ovendried pulp is consumed.

Claim 14

A process for bleaching wood pulp which comprises: (a) mixing an aqueous slurry of wood pulp, at a consistency from 0.1% to 10% by weight of ovendried pulp and having a pH ranging from 2 to 7, with 0.01% to 1.0% cationic surfactant by weight based on ovendried pulp, said cationic surfactant being selected from the group consisting of ##STR3## wherein R is CH 3 or CH 2 CH 3 , R 1 is an alkyl radical containing from 3 to 15 carbon atoms, an aryl radical or an alkylaryl radical and X is a halogen; and (b) bleaching said slurry, containing said cationic surfactant, with ozone at a temperature from room temperature to about 100° C. until from 0.5% to about 3.0% by weight of ozone based upon the weight of ovendried pulp is consumed.

Claim 15

The process according to claim 12 wherein said aqueous slurry of pulp is at a consistency from 1.0% to 5.0% by weight of ovendried pulp.

Claim 16

The process according to claim 13 wherein said cationic surfactant is present in an amount from 0.1% to 0.5% by weight of ovendried pulp.

Claim 17

The process according to claim 14 wherein said cationic surfactant is a member of the group consisting of hexadecyl trimethyl ammonium bromide, nonyl trimethyl ammonium bromide and dodecyl trimethyl ammonium bromide.