Process for the production of a microfibrillated cellulose composition

A process for the production of a microfibrillated cellulose composition, the process comprising:

• subjecting an aqueous mixture comprising 30 to 70% by weight of cellulose containing fibers to mechanical shearing at a temperature of from 40° C. to 120° C. in the presence of at least one thermostable biocide thereby forming the microfibrillated cellulose,
• wherein the microfibrillated cellulose in the composition has a weight-weight averaged fiber length of 800 μm determined according to Tappi standard T 271 and a percentage of a fiber in the composition having a length of 200 μm or less is about 19%, and
• wherein the thermostable biocide is a combination of octylisothiazolinone, glutaraldehyde, and sodium pyrithione,
• wherein the octylisothiazolinone is utilized in an amount of 185 parts per million on a weight by weight basis, the glutaraldehyde is utilized in an amount of 460 parts per million on a weight by weight basis, and the sodium pyrithione is utilized in an amount of 200 parts per million on a weight by weight basis,
• wherein the thermostable biocide is added during the step of mechanical shearing, and
• wherein the cellulose containing fibers are derived from linerboard from recycled paper and/or old corrugated carton.