Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Waste paper or textile waste
Patent
1996-04-09
1998-03-17
Czaja, Donald E.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Waste paper or textile waste
162 76, 162 78, D21C 502
Patent
active
057282633
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to the use of dialdehydes and acetals thereof for inhibiting decomposition of peroxide in the production and the treatment of recycled fiber pulp and other fiber pulp.
BACKGROUND OF THE INVENTION
Hydrogen peroxide is used in the production of recycled fiber pulp and other fiber pulp to enhance brightness. On account of its highly oxidizing effect, hydrogen peroxide has also been used with varying success for destroying bacteria. The effect of hydrogen peroxide is reduced by certain metal ions that are present in water. To obviate this problem, chelate formers have been used for binding the metal ions. Another difficult problem is the decomposition of peroxide for other reasons, e.g. because of the effect of peroxide-decomposing enzymes. These enzymes are produced by microbial action. One of such enzymes is catalase, one molecule of which decomposes 40 000 peroxide molecules at the temperature of 0.degree. C. in one second (the Encyclopedia of Biochemistry, Roger J. Williams, Edwin M. Lansford Jr., page 634).
It has now been unexpectedly found that the use of dialdehydes or acetals thereof in the production and treatment of recycled fiber pulp and other fiber pulp renders it possible to inhibit and control enzymatic decomposition of peroxide. This is advantageous not only in view of brightness but also in view of control of microbes, as in this way the effect of residual peroxide, which also destroys bacteria, occurs more widely in the process. The invention opens new prospects for control and management of process chemistry, as one factor which has so far been uncontrollable can now be eliminated.
SUMMARY OF THE INVENTION
The invention relates thus to the use of dialdehydes and acetals thereof for inhibiting decomposition of peroxide in the production and the treatment of recycled fiber pulp and other fiber pulp.
Suitable dialdehydes are straight-chain and cyclic aliphatic dialdehydes which contain preferably 2 to 8 carbon atoms and which may be C-substituted and contain heteroatoms, such as glyoxal, succinic aldehyde, glutaraldehyde, methyl-glutaraldehyde, octanediale and oxa-glutaraldehyde. Other suitable dialdehydes are aromatic dialdehydes which contain preferably 6 carbon atoms and which may be substituted and contain heteroatoms, such as o-phthalic aldehyde, m-phthalic aldehyde and p-phthalic aldehyde.
Suitable acetals of dialdehydes, including semiacetals, are those where the alcoholic component of the acetal is a primary, secondary or tertiary alcohol, such as carbohydrate, e.g. glucose. Specific examples of acetals are those having the formulae ##STR1## and 1,6-dihydroxy-2,5-dioxa-hexane.
According to the invention, it is possible to use either a single dialdehyde or acetal or a mixture of two or more dialdehydes or acetals.
The amount of the dialdehyde or acetal used may vary over a wide range depending on the process that is employed. The amount is, however, typically 0.5 to 250 ppm, preferably 2 to 75 ppm, specifically 15 to 50 ppm, based on weight. As the processes are rather different, the amount of the dialdehyde or acetal can also be indicated as follows: typically 0.05 to 2 kg, preferably 0.1 to 1 kg, specifically 0.2 to 0.6 kg, per one ton of produced fiber pulp (dry matter). The dialdehyde or acetal is introduced suitably into a pulper or before a pulper into raw water, white water of the process or chemical solutions. The dosage can be effected periodically, e.g. as so-called shock dosage, or continuously as maintenance dosage. To prevent loss of brightness after bleaching, it is advantageous that the process contains so-called residual peroxide. It is thus also useful to introduce a dialdehyde or an acetal after bleaching into dilution water, which may contain a catalase enzyme.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the effect of glutaraldehyde on the residual hydrogen peroxide in process water.
FIG. 2 shows the effect of succinic aldehyde on the residual hydrogen peroxide in process water.
FIG. 3 shows the effect of o-pht
REFERENCES:
patent: 2676871 (1954-04-01), McGovern
patent: 4844886 (1989-07-01), Hartmann et al.
patent: 4875973 (1989-10-01), Heikkila et al.
Zakatov, A.N., "Means of increasing . . . Mech Pulp", May 1990, Abstract.
Singh, Devendra Deo Narain, "Preparation of . . . base alloys" Feb. 1989, Abstract.
Mattila Pertti
Zeller Dieter
Cellkem OY
Czaja Donald E.
Nguyen Dean T.
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