Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1
10131
METHOD OF DEINKING WASTE PAPER FOR REC~~MATION THEREOF
Field of the Inventio
This invention relates to a method of deinking waste
paper for reclamation thereof. More particularly, the
invention relates to a method of deinking waste paper such
as newspapers or magazines using a specific higher alcohol
polyoxyalkylene ether or alkylphenol polyoxyalkylene ether
as a deinking agent in the known floatation method to
provide deinked pulp having a high degree of whiteness and
low residual ink droplet number.
Description of the Prior Art
Waste paper such as newspapers or magazines have been
reclaimed by disintegrating the waste paper~to pulp fibers
and then removing printing ink components such as carbons
or vehicles from the pulp fibers to recover the pulp fibers
for reuse as paper making material. The reclamation of
waste paper becomes more important on account of shortage
of wood resources and rise in their prices, and there is a
strong demand for a higher performance deinking agent since
_ it becomes more difficult to deink the recent waste paper
on account of changes in the printing techniques, printing
systems and printing ink compositions.
The floation method has been known as a representative
of the deinking methods of waste paper for its reclamation.
According to the floation method, the waste paper is
disintegrated with an alkali in water to provide an aqueous
slurry of pulp fibers, a deinking agent is added thereto
CA 02126723 2004-04-15
27571-50
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to remove the ink components from the waste paper and allow
the ink composition to coagulate, blowing the air into
the slurry so that it foams and the inx composition adheres
to the foam, and then the foam is removed from the slurry
together with the ink composition to leave deinked pulp
fibers. The resultant pulp fibers are bleached for reuse
as paper making material.
A variety of surfactants have been used as a deinking
agent in the floation method, and a higher fatty acid soap
such as stearic acid soap is a representaive. The higher
fatty acid soap has a high performance for removing ink
compositions from waste paper. However, the higher fatty
acid soap is not sufficiently foamable so that the
coagulated and floated ink composition is incompletely
removed, and thus the recovered pulp fibers have still a
many number of ink spots therein. There is also a tendency
that the released ink composition deposits on the deinking
device used. Moreover, it is necessary to use the higher
fatty acid soap in a large amount to obtain intended
deinking results, and accordingly the deinking cost is high.
In order to solve these problems, there have been
recently proposed a number of deinking agents other than
the higher fatty acid soap, among which are anionic
surfactants such as sodium alkylbenzenesulfonates, higher
alcohol sulfate salts, alpha-olefin sulfonates or
dialkyl sulfosuccinates; or nonionic surfactants such as
higher alcohols, alkylphenols, ethylene oxide and/or
propylene oxide adducts to higher alcohols or alkylphenols.
Very recently, there has been proposed a deinking
agent containing a higher alcohol polyoxyethylenepropylene
ether, as disclosed in Japanese Patent Application Lid-open
No. 55-51891, or a deinking agent comprising a higher
alcohol polyoxyethylenepropylene ether together with a
fatty acid or its salt, as disclosed in Japanese Patent
Application Lid-open No. 61-186592. A further deinking
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agent is also known which contains, as one of the components,
a higher alcohol polyoxyethylenepropylene ether, as disclosed
in Japanese Patent Application Lid-open I~o. 63-165592.
The above mentioned agents are improved in many
respects compared with the higher fatty acid soap, however,
the ink removal performance when used in the floation
method is not satisfactory.
Brief Summary of the Invention
It is, therefore, an object of the invention to
provide a method of deinking waste paper such as newspapers
or magazines using a specific deinking agent in the known
floatation method to provide deinked pulp having a high
degree of whiteness and low residual ink droplet number.
The invention provides a method of deinking waste
paper for reclamation thereof, which comprises disintegrating
waste paper with an alkali in water in the presence of a
polyoxyalkylene ether compound having the formula
R-0 (PO) x (AO) y (PO) z-H
wherein R is an alkyl or alkenyl of 8-22 carbons, or an
alkylphenyl wherein the alkyl has 4-12 carbons; PO is an
oxypropylene group; and AO is an oxyethylene group, or a
mixed oxyalkylene group composed of an oxyethylene group
and at least one oxyalkylene group selected from the group
consisting of an oxypropylene group and an oxybutylene
group; and x is a numeral of 3-15, y is a numeral of 20-40,
and z is a numeral of 5-20, as a deinking agent.
Detailed Descript
The polyoxyalkylene ether compound used in the
invention as a deinking agent is either a polyoxyalkylene
ether of a higher alcohol ROH wherein R is an alkyl or
alkenyl of 8-22 carbons or a polyoxyalkylene ether of an
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4
alkylphenol ROH wherein R is alkylphenyl wherein the alkyl
has 4-12 carbons.
The polyoxyalkylene ether compound is structurally
featured by that it has oxypropylene groups ((PO)x) bonded
to the RO group derived from the higher alcohol or
alkylphenol as well as oxypropylene groups ((PO)z-H) at
the end of the molecule.
Since the deinking agent used in the method of the
invention contains the above polyoxyalkylene ether
compound as a deinking agent which is well-balanced in
dispersibility and coagulating ability of ink compositions,
and thus the use of the deinking agent according to the
invention in the floatation method provides deinked pulp
having a high degree of whiteness and low residual ink
droplet number.
It is preferred that the polyoxyalkylene ether
compound has an average molecular weight 1000-8000, more
preferably 2000-3000, since such a polyoxyalkylene ether
compound has especially eminent deinking effects.
A further feature of the polyoxyalkylene ether
compound is that it is liquid at normal temperatures, and
it can be added as it is to a disintegrator when waste
paper is disintegrated in water so that the energy cost
for deinking treatment is greatly reduced.
The higher alcohol polyoxyalkylene ether may be
produced by a known method in which, as higher alcohol
components, there may be used, for example, octyl alcohol,
lauryl alcohol, cetyl alcohol or stearyl alcohol. A
synthetic alcohol such as an oxo alcohol or a secondary
alcohol may also be used as the higher alcohol component.
The higher alcohol component may be used singly or as a
mixture of two or more. In turn, the alkylphenol
polyoxyalkylene ether may also be produced Iby a known
method in which, as alkylphenol components, there may be
used, for example, octylphenol, nonylphenol or dodecylphenol.
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The alkylphenol component may also be used singly or as a
mixture of two or more.
In the above formula, AO is an oxyethylene group, or
a mixed oxyalkylene group composed of an oxyethylene group
5 and at least one oxyalkylene group selected from the group
consisting of an oxypropylene group and an oxybutylene
group. Thus, the AO may be an oxyethylene group,
oxyethylene/oxypropylene group, oxyethylene,/oxybutylene
group, oxyethylene/oxypropylene/oxybutylene group or an
oxybutylene group. These oxyalkylene groups may be in the
form of random copolymers or block copolymers.
According to the method of the invention, the
polyoxyalkylene ether compound is used in the stage of
disintegrating waste paper in water with an alkali such as
sodium hydroxide usually in an amount of 0.2-1.0% by
weight based on the waste paper, although not limited to
the exemplified.
The method of the invention has an important feature
in that the deinking agent can be used as a one component
agent. However, the agent may be used together with any
known deinking agent such as anionic surfactants or nonionic
surfactants, for example, a higher fatty acid, a higher
alcohol, a higher alcohol sulfate salt, a sulfate salt of
ethylene oxide adducts to higher alcohols, alkylbenzene
sulfonates, or alkylphenols.
As above set forth, the method of the invention uses
such a specific higher alcohol polyoxyalkylene ether or
alkylphenol polyoxyalkylene ether as a deinking agent in
the floatation method for waste paper reclamation, and thus
the method provides deinked pulp having a high degree of
whiteness and low residual ink droplet numbE3r. In addition,
the deinking agent used is a one component liquid agent so
that it can be used easily and reduces the Energy required
in the floatation method in the deinking process.
The invention will be described in mor°e detail with
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reference to examples, however, the invention is not limited
to the examples.
Examples
Eighty percent by weight of waste newspapers (offset/
relief ratio: 6/4) and 20% by weight of waste leaflets were
cut into pieces and placed in a bench disintegrator (JIS
P-8209), to which were then added 1.5% by weight of sodium
hydroxide, 3.5% by weight of No.3 sodium silicate, 1.0% by
weight of a 30% aqueous solution of hydrogen peroxide and
0.3% by weight of a deinking agent indicated in Table 1,
each based on the weight of the waste paper;, and then warm
water so that the resultant aqueous slurry contained the
waste paper in an amount of 10% by weight. The waste paper
was then disintegrated at 55°C for 20 minutE:s. The resultant
pulp slurry was diluted to a pulp concentration of I% by
weight, and then the floatation treatment was carried out
at 30°C for 10 minutes with the use of a te:;ting floatator.
The resultant pulp slurry was formed into a sheet
having a weight of 150 g/m2 using a standard type sheeting
machine (JIS P-8209). The whiteness of the sheet was
measured with a Hunter whiteness meter according to JIS P-
8123. The residual ink droplet number was measured with
an image analyzer (x100). The results are summarized in
Table l, in which E0, P0, BO and Ph represent oxyethylene,
oxypropylene, oxybutylene and phenyl group, respectively.
35
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As seen in Table 1, the method of the invention
provides deinked pulp having a higher degree of whiteness
and lower residual ink droplet number than a method wherein
a higher alcohol polyoxyalylene ether or an alkylphenol
polyoxyalylene ether which has oxyethylene groups bonded
to the alkyloxy group derived from higher alcohol or the
phenoxy group derived from alkylphenol is used as a deinking
agent.
It is further noted that the use of the polyoxyalylene
1d ether compound which contains oxypropylene groups and
oxyethylene groups (or oxyalkylene groups) in a specific
range of molar ratios provides especially erninent deinking
results.
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