U.S. patent application number 10/548205 was filed with the patent office on 2006-08-03 for manufacturing process of a paper substrate intended to be vulcanised or parchmentised.
Invention is credited to Noel Cartier.
Application Number | 20060169427 10/548205 |
Document ID | / |
Family ID | 32922217 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060169427 |
Kind Code |
A1 |
Cartier; Noel |
August 3, 2006 |
Manufacturing process of a paper substrate intended to be
vulcanised or parchmentised
Abstract
A manufacturing process of a paper substrate intended to be
vulcanised or parchmentised, consisting in: subjecting, in a dry
state, the cellulose fibres to energy radiation; defiberizing and
refining in an aqueous environment the irradiated fibres until a
homogenous fibre solution is obtained; forming a web from the
obtained fibre suspension, which is then drained and dried to
obtain the actual paper substrate.
Inventors: |
Cartier; Noel; (Vienne,
FR) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Family ID: |
32922217 |
Appl. No.: |
10/548205 |
Filed: |
March 15, 2004 |
PCT Filed: |
March 15, 2004 |
PCT NO: |
PCT/FI04/00147 |
371 Date: |
September 7, 2005 |
Current U.S.
Class: |
162/9 ; 162/141;
162/147; 162/182; 162/4; 162/95 |
Current CPC
Class: |
D21B 1/00 20130101; D21B
1/02 20130101; D21H 11/12 20130101; D21H 25/04 20130101; D21H 25/02
20130101 |
Class at
Publication: |
162/009 ;
162/141; 162/095; 162/147; 162/004; 162/182 |
International
Class: |
D21H 25/04 20060101
D21H025/04; D21B 1/32 20060101 D21B001/32; D21B 1/20 20060101
D21B001/20 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2003 |
FR |
0303229 |
Claims
1. A manufacturing process of a paper substrate intended to be
vulcanised or parchmentised, comprising the steps of subjecting, in
a dry state, the cellulose fibres to energy radiation, separating
and refining in an aqueous environment the radiation-treated fibres
until a homogenous fibre solution is obtained, forming a web from
the obtained fibre suspension, which is then drained and dried to
obtain the actual paper substrate.
2. A process according to claim 1, characterized in adding to the
fibre suspension being exposed to energy radiation, cellulose
fibres of the same origin, exposed to energy radiation or not,
and/or cellulose fibres of different origin, exposed to energy
radiation or not, and/or synthetic and/or mineral non-cellulose
fibres.
3. A process according to claim 1, characterized in that the fibre
suspension contains at least 20%, advantageously at least 50% by
weight of the cellulose fibres exposed to energy radiation.
4. A process according to claim 1, characterized in that the
cellulose fibres exposed to energy radiation are cotton fibres.
5. A process according to claim 4, characterized in that the cotton
fibres exposed to energy radiation are virgin cotton fibres coming
from sheets or compressed pulp.
6. A process according to claim 5, characterized in that the energy
radiation is a radiation by electron beams or by x-radiation.
7. A process according to claim 4, characterized in that the cotton
fibres exposed to energy radiation come from textile industry
waste.
8. A process according to claim 7, characterized in that the cotton
fibres come from jeans waste first cut, then sorted and shredded,
the fibres being exposed to a radiation by electron beams either
right after the cutting step, and prior to the shredding step, or
right after the shredding step.
9. A process according to claim 7, characterized in that the cotton
fibres come from jeans waste in the form of bales containing the
jeans manufacture rags, possibly cut and then shredded, the entire
bale being exposed to X-radiation.
10. A process according to claim 4, characterized in that, when the
paper is intended to be vulcanised, the irradiation dose absorbed
by the cotton fibres is between 10 and 30 kGy.
11. A process according to claim 4, characterized in that, when the
paper is intended to be vulcanised, the DP of the irradiated cotton
fibres is between 350 and 500.
12. A process according to claim 4, characterized in that, when the
paper is intended to be parchmentised, the irradiation dose
absorbed by the cotton fibres is between 5 and 20 kGy.
13. A process according to claim 4, characterized in that, when the
paper is intended to be parchmentised, the degree of polymerisation
of the irradiated cotton fibres is less then 700.
14. A manufacturing process of a paper intended to be vulcanised or
parchmentised comprising the steps of: separating and refining in
an aqueous environment cellulose fibres contained in a mixture of
fibres until a homogenous fibre suspension is obtained, forming a
web from the suspension, which is next drained and dried until the
actual paper substrate has been obtained, and lowering the degree
of depolymerisation of the fibres by exposing the paper substrate
to energy radiation.
15. A process according to claim 14, characterized in that the
mixture of fibres contains at least 20%, preferably at least 50% by
weight, most preferably 100% by weight of the cellulose fibres.
16. A process according to claim 14, characterized in that the
cellulose fibres are exclusively virgin cotton fibres coming from
sheets or compressed pulp.
17. A process according to claim 14, characterized in that the
cotton fibres, defiberized and then refined in an aqueous
environment, come from textile waste.
18. A process according to claim 17, characterized in that the
textile waste comes from jeans industry.
19. A process according to claim 14, characterized in that the
fibre suspension contains 100% by weight of cotton fibres.
20. A process according to claim 14, characterized in that the
energy radiation is a radiation by electron beams.
21. A process according to claim 19, characterized in that, when
the paper is intended to be vulcanised, the radiation dose absorbed
by the cotton fibres is between 10 and 50 kGy.
22. A process according to claim 19, characterized in that, when
the paper is intended to be vulcanised, the degree of
polymerisation of the irradiated cotton fibres is less then 700,
advantageously between 200 and 300.
23. A process according to claim 19, characterized in that, when
the paper is intended to be parchmentised, the degree of
polymerisation of the irradiated cotton fibres making up the
obtained paper sheet is between 400 and 600, advantageously
500.
24. A process according to claim 19, characterized in that, when
the paper is intended to be parchmentised, the irradiation dose
absorbed by the cotton fibres is between 5 and 30 kGy.
25. A process for vulcanizing a paper substrate comprising
providing a paper substrate obtained by the process of claim 1, and
subjecting the paper substrate to a vulcanizing operation.
26. A process for parchmentising a paper substrate comprising
providing a paper substrate obtained by the process of claim 1, and
subjecting the paper substrate to a parchmentising operation.
Description
[0001] The invention relates to a manufacturing process of a paper
substrate intended to be vulcanised or parchmentised. Thus, it also
relates to the substrate obtained with the vulcanising or
parchmentising process.
[0002] Those skilled in the art know the vulcanising and
parchmentising operations so well that these processes will not be
described more in detail hereinafter. The main thing is that the
vulcanising is an operation consisting in treating a paper
substrate by immersing it into a zinc chloride solution, and the
parchmentising is a similar operation, in which the zinc chloride
is replaced by sulphuric acid. The present invention does not
relate to the actual vulcanising and parchmentising operations, but
it relates to the manufacturing process of webs that can be treated
with the operations of these two types.
[0003] The ability of a substrate to be treated by vulcanising or
parchmentising depends mainly, if not exclusively, on the
reactivity of the cellulose fibres making up the web with regard to
the zinc chloride or sulphuric acid solutions. Thus, the more
reactive i.e. accessible to chemical components contained in the
ionic solutions the cellulose fibre is; the more satisfactory is
the vulcanising or parchmentising. The reactivity of a fibrous web
depends on several factors, one of which is especially the degree
of polymerisation (DP) of the cellulose making up the fibre, the
latter corresponding to the number of repetition units, which form
the cellulose polymer. In general, it looks like the weaker the DP
is, the more reactive is the fibre.
[0004] In the rest of the application, the efficiency of the
vulcanising or of the parchmentising is controlled by evaluating
the barrier level of the obtained vulcanised or parchmentised paper
according to a technique, which will be made clear in the
examples.
[0005] At the moment, the number of webs intended to be vulcanised
is manufactured from textile waste coming especially from the
"jeans industry", the jeans consisting 100% of long cotton fibres
(staple), the size of which is between 20 and 50 mm. In practice,
the jeans manufacturing clippings or rags are in the form of a
bale, which is then opened and the size of the rags is reduced by
different operations such as cutting and shredding. When these
different steps have come to an end, the shredded pieces of jeans
are cooked in a solution of soda concentrated to 7% in a closed
reactor, under pressure, at a temperature of about 150.degree. C.
Then follows the tiresome step, in which the cooked fibres are
washed with water in order to eliminate all of the cooking liquor.
All these necessary operations of this discontinuous process may
lead to duration of about 24 hours.
[0006] Soda cooking step allows both opening of the cotton fibres
and reducing the degree of polymerisation of the cellulose. In
practice, when the cotton fibres making up the jeans have, before
cooking, an average degree of polymerisation of about 2000, this
degree is only about 600, as far as vulcanising and parchmentising
are concerned, immediately after the cooking step. The value of 600
seems in fact sufficient for obtaining reactivity, and consequently
a satisfactory ability of the base paper to vulcanising or
parchmentising.
[0007] The clusters of cooked fibres are processed in an aqueous
environment so as to separate the fibres from each other, after
which the individual fibres are refined, i.e. their structure is
subjected to a deformation by mechanical action, allowing
optimising the accessibility of the fibre. The suspension of the
individual cotton fibres obtained right after these steps is then
deposited on the wire of the paper machine, in the presence, or
not, of fibres having different kind or same kind of nature such as
e.g. wood fibres, so as to form in a known manner a web, which is
then drained and dried until the actual paper substrate is
obtained.
[0008] As already said, it is necessary, before vulcanising or
parchmentising, to set out the most reactive cellulose fibres into
the paper, this reactivity being obtained by lowering strongly the
degree of polymerisation of the cellulose fibres.
[0009] The cooking step allowing obtaining this result has,
however, some inconveniences. At first, the capital costs of an
industrial chemical reactor are relatively high. Subsequently, the
cooking consumes a lot of chemicals, in the case in question, soda.
Finally and above all, the cooking leads to the formation of
coloured effluents of concentrated soda having a pH of 13,5, the
elimination of which is especially difficult and polluting. These
operations of cooking and washing the rags take place generally
with a yield in the order of 85% meaning a loss of the raw material
of about 15%.
[0010] In other words, the invention tends to solve the problem by
developing a clean and economical high yield (over 85%)
manufacturing process of paper substrates intended to be vulcanised
or parchmentised, which would be at least as reactive with regard
to the zinc chloride or sulphuric acid solutions as the substrates
obtained by the processes using a chemical cooking step of the
cellulose fibres with a high degree of polymerisation.
[0011] To do this, the Applicant had the idea of substituting the
cooking step in the concentrated soda solution with an energy
radiation step, this radiation step being able to be performed,
either, in a dry state, directly on the cellulose fibres, before
the individualisation of the fibres and the refining in the aqueous
environment, or in a dry state, on the final paper.
[0012] In other words and in a first embodiment, the invention
relates to a manufacturing process of a paper substrate intended to
be vulcanised or parchmentised, comprising the steps of:
[0013] subjecting, in a dry state, the cellulose fibres to energy
radiation,
[0014] separating and refining in an aqueous environment the
radiation-treated fibres until a homogenous fibre dispersion is
obtained,
[0015] forming a web from the obtained fibre suspension, which is
thereafter drained and dried to obtain the actual paper
substrate.
[0016] The expression "homogenous fibre suspension" denotes a
suspension, in which the cellulose fibres are dispersed into an
aqueous solution to a consistency of about 1 to 10% by weight. This
suspension is called homogenous insofar as the fibres have been
correctly individualized due to hydration and mechanical agitation
operations, thus avoiding the clustering of fibres.
[0017] In other words, the process consists first of all in
lowering, with the energy radiation, in a dry state, the degree of
polymerisation of the cellulose fibres, and once such a degree of
polymerisation has been achieved, that the reactivity of the fibre
is sufficient, separating the fibres in an aqueous environment and
refining them, the fibre suspension next being settled on the wire
of a paper machine to form a web, which is then drained and
dried.
[0018] In another embodiment of the invention, the cellulose fibres
are not exposed to energy radiation before the web formation, but
thereafter, by the direct radiation of the final paper substrate
intended to be vulcanised or parchmentised.
[0019] In this case, the process comprises the steps of:
[0020] separating and refining in an aqueous environment cellulose
fibres contained in a mixture of fibres until a homogenous fibre
suspension has been obtained,
[0021] forming a web from said suspension, which is next drained
and dried until the actual paper substrate has been obtained,
and
[0022] finally, exposing the paper substrate to energy
radiation.
[0023] In the rest of the description and in the claims, the
expression "cellulose fibres" denotes fibres formed by definition
of cellulose, such as cotton fibres or any other annual plant
fibres (flax, abaca etc.), wood fibres, these fibres of different
origin distinguishing from each other by the structural
characteristics such as the shape, the cross-section and thickness
of the walls and the average degree of polymerisation (DP) of the
cellulose making them up.
[0024] In the embodiment according to which the energy radiation is
carried out before obtaining the sheet, it is possible to add to
the fibre suspension, containing the cellulose fibres being exposed
to energy radiation, cellulose fibres of the same origin, exposed
to energy radiation or not, and/or cellulose fibres of different
origin, exposed to energy radiation or not, and/or synthetic and/or
mineral non-cellulose fibres.
[0025] In practice, the cellulose fibres treated with energy
radiation are advantageously annual plant fibres and especially of
cotton and represent at least 20%, advantageously at least 50% by
weight, of the fibre suspension.
[0026] In the embodiment according to which the radiation is made
directly on the paper substrate, all the cellulose fibres contained
in the paper are irradiated by electron beams, regardless of their
origin. It is clear that the mixture of fibres may further contain
cellulose fibres, synthetic and/or mineral non-cellulose fibres. In
practice, the cellulose fibres represent at least 20%, preferably
at least 50% by weight, the most preferably 100% by weight of the
fibre composition. In an advantageous embodiment, the cellulose
fibres consist exclusively of cotton fibres.
[0027] When the paper substrate contains cotton fibres as cellulose
fibres, the cotton fibres may have two essential sources.
[0028] First of all, the cotton fibres may be virgin cotton fibres,
advantageously long fibres, the length of which is between 20 and
50 mm. In practice, these cotton fibres are received by the paper
manufacturer in a dry state, either in the form of sheets, or in
the form of compressed pulp thus comprising 100% of cotton
fibres.
[0029] In this case, the energy radiation is in the form of a
radiation by an electron beam or an X-ray beam.
[0030] When the irradiation treatment is carried out before the
sheet formation and by means of X-ray, the penetration of the
radiation is sufficient so that the cotton pulp is directly treated
in a bale of about 1 m.sup.3.
[0031] When the radiation is performed before the sheet formation
and by an electron beam, the dry defibering of the sheet or of the
compressed pulp starts prior to the radiation step and this, is
done in such a way that the material passing under the beam is of
low density (<0,6) and thin (in the order of a centimetre) so
that the cotton fibres are treated in a homogenous and efficient
manner.
[0032] As already said, the paper substrates intended to be
vulcanised or parchmentised can also advantageously be obtained
from cotton fibres coming from textile industry waste. In an
advantageous embodiment, the cotton fibres coming to the
composition of the fibre suspension come from jeans industry. In
this case, the raw material is in the form of jeans manufacturing
rags compacted in the form of bales.
[0033] In practice, the bale is first opened, the jeans rags are
cut, possibly sorted to remove the foreign objects e.g. of metallic
particle type, and finally shredded.
[0034] When the paper substrate is manufactured continuously, the
cellulose fibres obtained after the shredding are separated and the
refined in an aqueous environment.
[0035] When the paper substrate is manufactured discontinuously,
the fibres obtained from shredded rags are stored again in the form
of a bale, which is opened, and the cellulose fibres are separated
and finally refined in an aqueous environment.
[0036] In a first embodiment, when the radiation is a radiation by
electron beams and takes place before the paper sheet formation,
the radiation treatment can be performed either immediately after
the cutting step and prior to the shredding step or immediately
after the shredding step.
[0037] In a second embodiment, the radiation is an X-radiation
performed directly on the bale containing the cut and shredded rags
of jeans.
[0038] As already said, the reactivity of a cellulose fibre depends
on its DP.
[0039] The Applicant has noticed that for obtaining a cotton fibre
treated by energy radiation that would be as reactive as the same
fibre treated by cooking, it is necessary to reduce its degree of
polymerisation under that of the cooked fibre.
[0040] Further and as already said, it is known that the degree of
reactivity of a cotton fibre doesn't necessarily have to be of the
same level, depending on whether the fibre is intended to be
vulcanised or parchmentised.
[0041] Further, the Applicant has noticed that for a same
reactivity level, the DP of a cellulose fibre absorbing a given
dose of irradiation before the sheet formation was higher than that
of the same fibre having absorbed the same dose from the final
paper.
Case in Which the Cotton Fibre is Exposed to Energy Radiation,
Electron beam or X-Ray before the Sheet Formation:
[0042] When the degree of polymerisation of a cooked fibre intended
to be vulcanised is in the order of 600, it is necessary, for
obtaining a reactivity of at least equal to the same fibre treated
by energy radiation, to reduce this degree of polymerisation to a
value between 350 and 500, advantageously equal to 450. To obtain
such DP-values, the irradiation dose absorbed by the cotton fibres
is between 10 and 30 kGy.
[0043] The degree of polymerisation of a cellulose fibre treated by
cooking and intended to be parchmentised is about 1000. To obtain a
reactivity vis-a-vis the concentrated sulphuric acid at least equal
to the same fibre treated by energy radiation, it is necessary to
reduce this degree of polymerisation to a value less then 700, so
that the irradiation dose absorbed by the fibres should be between
5 and 20 kGy.
[0044] Generally, the absorbed irradiation dose necessary to the
cellulose fibre for obtaining an optimal reactivity of the
substrate with regard to vulcanising and parchmentising depends on
the treatment conditions and in particular of the type of equipment
used.
Case in Which the Cotton Fibre is Irradiated after the Sheet
Formation:
[0045] When the paper sheet manufactured exclusively of cotton
fibres is intended to be vulcanised, the degree of polymerisation
of the fibres making up the paper sheet obtained is less than 700,
advantageously between 200 and 300, preferably 250. To obtain such
a value, the Applicant has noticed that the irradiation dose
absorbed by the cotton fibres should be between 10 and 50 kGy.
However, these values can be applied only to vulcanising.
[0046] In the case of parchmentising, when the paper is
manufactured solely from cotton fibres, the degree of
polymerisation of the fibres making up the paper sheet obtained is
between 400 and 600, advantageously 500. To obtain such a value,
the Applicant has noticed that the irradiation dose absorbed by the
cotton fibres should be between 5 and 30 kGy.
[0047] The manufacturing processes of the paper substrate of the
invention, depending on whether the energy radiation treatment is
performed before or after the sheet formation, can be carried out
continuously or discontinuously.
[0048] The invention and the advantages, which stem therefrom will
become more apparent from the following embodiment examples.
EXAMPLE 1
[0049] In this example, the process is a discontinuous process
consisting in cutting the textile waste, removing the foreign
bodies and shredding the pieces before forming a bale. This
sequence of steps is made continuously on suitable cutting, sorting
and shredding machines, known to those skilled in the art.
[0050] The baling step makes it easier to store the ready-made raw
material for a subsequent dispersion step of the fibres in an
aqueous environment.
[0051] When the paper manufacturer takes again the jeans waste
bale, he opens it in a dry state so that the bale is broken. The
pieces of the jeans are then separated, defiberized and then
refined in an aqueous environment, the obtained fibre suspension
then being deposited on a paper machine, which assures, after
draining and drying, the manufacturing of the final paper.
[0052] In the prior art, the obtained shredded pieces of jeans,
after the dry disintegration of the bale, are subjected to a
cooking step in a cooker at the temperatures of about 150.degree.
C. in soda solutions concentrated to 7%, the matter obtained being
washed and defiberized, and finally refined in an aqueous
environment.
[0053] In the process object of the an exemplary embodiment of the
present invention, this cooking and washing step is replaced by a
radiation step by electron beams.
[0054] This irradiation step can be performed on the cotton fibres
before manufacturing the paper and this, either immediately after
the sorting step or immediately after the shredding step, or
directly on the finished sheet.
EXAMPLE 2
[0055] In this example, a paper intended to be vulcanised is
produced containing 100% of cotton fibres treated either by cooking
or by irradiation before the sheet formation.
A/Method
[0056] For the two samples, the degree of polymerisation of the
cooked cotton fibres or those exposed to radiation by an electron
beam has been determined before transformation operation of the
paper by vulcanising, as well as the reactivity of the final sheet
has been determined after the vulcanising. The degree of
polymerisation of the cotton fibres is determined by calculations
from the viscosity measurements of a solution based on
cupriethylenediamine (CED), into which the cellulose fibres are
dissolved.
[0057] The precise test from which the DP-values are obtained is
done as follows: [0058] placing the fibres in a polyethylene flask
containing 10 ml of de-ionized water under agitation, [0059] then
adding 10 mm of cupriethylenediamide, [0060] eliminating the air
from the flask by pressure on its walls, [0061] closing the flask
with its plug, [0062] agitating the solution for 40 minutes until
the fibres have been completely dissolved, [0063] filtering the
solution by means of a mechanical filter, [0064] measuring the
viscosity of the lower part of the filtrate by means of a capillary
viscosimeter CANON-FENSKE 200.
[0065] The reactivity of the paper (DL) is evaluated after the
vulcanising by measuring the barrier level with a coloured solvent.
The test is done as follows: [0066] preparing a sample of the paper
to be tested, the size of which is 10.times.10 cm, [0067] putting
the side of the sample to be tested on a transfer paper, [0068]
applying a coloured solution of turpentine on the whole surface of
the paper to be tested: the contact time being 3 minutes.
[0069] The evaluation is made in the following table:
TABLE-US-00001 SIDE OF THE PAPER TO SCALE BE TESTED TRANSFER PAPER
5 no stains no stains 4 4 spots maximum no stains 3 several spots
no stains 2 -- 4 spots maximum 1 -- several spots 0 -- 1-2 stains,
size 5-20 mm -1 -- more than 2 stains, 5-20 mm -2 -- size of the
stains over 200 mm -3 -- the whole surface is coloured
[0070] Generally, the higher the DL-value of the paper transformed
by the vulcanising is; the higher is the reactivity of the base
paper. The reactivity of a paper is consequently estimated by the
barrier level of the final product obtained.
B/Results
[0071] 1/ The DP's and DL's concerning the fibres treated by
radiation with different doses of absorbed energy before the sheet
formation are given in the following table: TABLE-US-00002 Dose in
kGy Basic Weight g/m.sup.2 DP DL 0 111 2010 0 10 109 640 1 15 109
525 2 20 107 515 2 25 112 370 2 30 110 390 3 50 110 330 3
[0072] It may be seen from the results that it is necessary, in
order to obtain a degree of reactivity of a paper treated by
radiation of the same level as that of a paper obtained from cooked
fibres (DL=3), to lower the degree of polymerisation of the treated
fibres to a value of about 390.
[0073] 2/ The DP and DL of a paper, the cotton fibres of which have
been cooked or treated by an electron beam, are given in the
following table, but we must bear in mind that the DP is evaluated
on the fibres before the transformation operation of the paper by
vulcanising. TABLE-US-00003 DP DL 1 Cooked cotton fibres 600 3 2
Paper irradiated with 50 250 3 kGy 3 Fibres irradiated with 30 390
3 kGy
[0074] The examples 2 and 3 of the table reveal the difference due
to raw material irradiation before manufacturing of the paper in
comparison with an irradiation on the finished paper. For the same
paper transformation level after vulcanising, that is to say for
the same reactivity level of the paper, a much more important dose
of irradiation has to be applied to the finished paper than to the
raw material.
EXAMPLE 3
[0075] In this example, a paper intended to be parchmentised is
manufactured, containing 100% of cotton fibres treated by
irradiation before the sheet formation.
A/Method
[0076] The samples are characterized by the degree of
polymerisation of the cotton fibres exposed to radiation by an
electron beam, before the transformation operation of the paper by
parchmentising, as well as by the reactivity of the sheet with
regard to the parchmentising.
[0077] The degree of polymerisation DP of the cotton fibres is
determined by calculation from the measurements of the viscosity of
a solution based on cupriethylenediamine (CED), in which the
cellulose fibres are dissolved.
[0078] The reactivity of the paper (DL) is evaluated after the
parchmentising, by measuring its barrier level with a coloured
solvent. TABLE-US-00004 B/ Measurements Dose in kGy DP DL 0 2010 1
10 640 5 30 400 5 50 320 5
[0079] As can be seen from the measurements, an irradiation by
electrons of the cotton fibres before the paper manufacturing with
a dose of 10 kGy is sufficient for lowering the DP of the cellulose
under 700 and making it capable of a good parchmentising.
* * * * *