Paper making and fiber liberation – Apparatus – With coating or impregnating means
Reexamination Certificate
1999-02-19
2001-06-26
Nguyen, Dean T. (Department: 1731)
Paper making and fiber liberation
Apparatus
With coating or impregnating means
C162S298000, C162S299000, C162S300000, C118S257000
Reexamination Certificate
active
06251226
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing paper and cardboard having watermarks or patterns and to the paper and cardboard thus obtained.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method for manufacturing papers and cardboards which makes it possible to produce a plurality of patterns or watermarks during paper manufacture without the need of interrupting the manufacturing process, thus avoiding downtimes caused by machine stops.
An object of the present invention is to provide an apparatus for producing watermarks or patterns in the paper being manufactured which can be applied on the conventional formation table or tape of a paper manufacturing plant of any suitable type.
Another object of the present invention is to provide papers and cardboards with watermarks or patterns obtained without using a conventional dandy roll.
A further object of the present invention is to make it possible to obtain papers or cardboards provided with security watermarks, i.e., watermarks which can be made visible only by adding chemicals which react with adapted markers.
According to the present invention, there is provided an apparatus for obtaining watermarks or patterns in paper or cardboard while being formed on a formation tape or table in a paper or cardboard manufacturing plant, comprising:
a primary fibrous mix source for storing a primary fibrous mix;
at least one manifold, which can be arranged proximate to the formation table;
at least one jet nozzle which can be fed by said at least one manifold and is arranged above said formation table so that it can be angularly adjusted with respect thereto;
a feeding duct for a secondary fibrous mix and a return duct from said at least one manifold; and
a secondary fibrous mix source arranged to supply the feeding duct and to receive material discharged from the feeding duct for return from said at least one manifold.
Advantageously, said source of cellulose mix comprises a feeder reservoir provided with an agitator, a delivery pump, and a filtration system, for feeding dyed and/or pigmented mix to the or each feed duct, a reservoir for storing the cellulose mix provided with a pump delivering to the feeder reservoir and with a level measuring device, and a dye or pigment reservoir arranged to feed the storage reservoir in a controlled manner.
BRIEF DESCRIPTION OF THE DRAWINGS
Further aspects and advantages of the method according to the present invention will become apparent from the following detailed description of some embodiments thereof, given only by way of non-limitative examples.
EXAMPLE 1
A primary fibrous mix was prepared which had softness and good rigidity characteristics and had the following composition:
cotton cellulose designed to give softness
8.5%
to the final product
mechanical wood pulp, adapted to give a
27.0%
fluffy effect to the final product
sulfate cellulose, adapted to give
64.5%
mechanical strength to the final product
Total
100.0%
Note: Throughout the present specification, the percentages are to be understood by weight unless otherwise specified.
This mix was spread on a formation table or tape of a conventional paper-manufacturing plant and was treated with an apparatus (described in detail hereinafter) with a plurality of jets of a mix having the same composition as that specified above, but pigmented with light dye.
The result was a dark gray paper affected by parallel lines approximately 1.2-1.3 mm wide which were significantly lighter in colour and integral with the paper body and suitable for giving a “pinstripe” appearance to the paper. The impact force of the jets in fact produced a continuous groove-shaped recess or hollow between the surface fibers of the body or base paper layer being formed, and a simultaneous application of secondary fibrous mix (as also specified hereinafter), i.e. dyed pulp-like material having the same composition as the base paper layer, which results in the filling of the grooved recess.
Since the base paper layer which advances on the tape is still relatively fluid, the formation of a groove simply causes fibers to move apart and to amalgamate and level out in the pulp-like layer immediately thereafter, thereby also acting as confinement sides or barriers for the applied material supplied by the jet.
EXAMPLE 2
The same procedure as in Example 1 was followed, but with a primary fibrous mix having the following composition:
cotton cellulose
15%
mechanical wood pulp
16%
sulfate cellulose
69%
Total
100%
The result was a rather resistant pinstripe paper with deep blue linear dashes. The linear dashes were obtained by rhythmically interrupting the jets of blue-dyed cellulose mix at a preset rate.
EXAMPLE 3
The same procedure as in Example 1 was followed, but using a primary fibrous mix having the following composition:
cotton cellulose
20%
mechanical wood pulp
34%
sulfate cellulose
46%
Total
100%
A relatively rigid pinstripe white paper with pale blue lines was obtained.
EXAMPLE 4
The same procedure as in Example 1 was followed, but using a primary fibrous mix having the following composition:
cotton cellulose
6%
mechanical wood pulp
16%
sulfate cellulose
78%
Total
100%
The result was a red paper affected by wave-shaped white lines obtained by causing the jets of fibrous mix to wave.
An average of the physical and mechanical characteristics of papers obtained according to the above Examples 1 to 4 is given in the following Table 1, which also indicates maximum and minimum tolerances.
TABLE 1
Unit of
Nominal
Tolerances
Type of
measure
value
min.
max.
analysis
Grammage
g/sq.m
100
98
102
primary
Thickness
micron
160
150
170
secondary
Absolute humidity
%
50
45
55
primary
Gurley air res.
sec.
30
15
50
secondary
Cobb index (felt)
g/sq.m
25
20
30
primary
Bursting strength
KPa
200
180
>
secondary
Tearing strength
longitudinal
mN
700
500
900
secondary
transverse
mN
700
500
900
secondary
Dry pulling strength
longitudinal
N/15 mm
60
50
>
secondary
transverse
N/15 mm
32
28
>
secondary
Dry pulling strength
longitudinal
%
2.0
1.8
>
secondary
transverse
%
4.0
3.0
>
secondary
Folding strength
longitudinal
no.
40
30
60
secondary
transverse
no.
30
20
50
secondary
Taber rigidity
longitudinal
U.T.
2.3
2.0
>
secondary
transverse
U.T.
2.0
1.5
>
secondary
The cotton cellulose used in the above Examples has a high content of alpha-cellulose designed to give the paper a soft touch which can be similar to the touch of fabric, whilst the mechanical wood pulp helps to give “fluffy” visual characteristics to the final paper.
Examples of composition of the secondary fibrous mix to be added by jet to a sheet of paper being formed in order to produce immediate monolithic composition are given hereafter.
Example A
To obtain a pinstripe effect of the final paper, with bluish lines at average viscosity for a finished paper grammage between 80 and 120 g/sq m, with a white color, the following composition was used for the secondary fibrous mix:
%
weight in grams
Cellulose fiber, in the same
2.2
22
proportion and with the same
composition as in the primary mix
Inorganic pigment
1.6
16
Surfactants
0.000016
0.00016
Direct blue dye
0.006
0.06
Antifoaming agent
0.0001
0.001
Water
96.193884
961.93884
Total
100
1000
Example B
The same procedure as in Example A was followed to obtain a pinstripe effect with bright red lines with high viscosity for a finished paper grammage between 130 and 250 g/sq.m in a plurality of colors (green, yellow, blue) by using the following composition for the secondary mix:
%
weight in grams
Cellulose fiber, in the same
3.7
37
proportion and with the same
composition as in the primary mix
Inorganic pigment
2.2
22
Surfactants
0.000018
0.00018
Dye
0.12
1.2
Antifoaming agent
0.00014
0.0014
Water
93.979842
939.79842
Total
100
1000
Example C
The same procedure as in Example A was followed in order to obtain a pinstripe effect with lemon yellow lines with very high viscosity for a finished paper grammage between 26
De Luca Alberto
Fedrigoni Giuseppe
Cartiere Fedrigoni & C. S.p.A.
Josif Albert
Modiano Guido
Nguyen Dean T.
O'Byrne Daniel
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