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Патент USA US2129995

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Patented Sept. 13, 1938
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I
2,129,995
UNITED STATES PATENT OFFICE
2,129,995
SAPONIFICATION OF ORGANIC ESTERS OF
CELLULOSE
Henry Dreyfus, London, England
No Drawing. Application September 5, 1935, Se
rial No. 39,287.
17, 1934
In Great Britain September
‘
- 5 Claims.
This invention relates to improvements in the
manufacture of arti?cial materials, and particularly to improvements in processes for the saponi?cation of arti?cial materials containing cellulose
5 acetate or other organic esters of cellulose.
The
saponi?cation of arti?cial materials con' _
(011. 8-20)
organic ester forming the basis of the arti?cial
materials being saponi?ed, and which are resist
ant to alkali and can be stripped from‘ the mate
rials after saponi?cation. Examples of such dye
stuffs are
5
Benzoazurme
G (Colour Index No. 502)
taming cellulose acetate or other organic ester
Benzopurpurin 43 (Colour Index NO_ 448)
of cellulose 1s well-known and 1s, 1n general, car-
Congo Oran e R (C01
ried out by treating them with media containing
10 caustic soda or other suitable basic substance for
exam 18 sodium Silicate ammonia or or 'anic
basesp The saponi?cation of the materialsgmay
.
be carried to a stage in which all the ester groups
are removed, or only a‘ partial saponi?cation of
15 the cellulose ester may be effected. The object
-
g
I d
N
459)
our n ex 0'
Dlrect steel Blue BB (Colour Index No‘ 465)
Benzo New Blue 5B (Colour Index No. 466)
10
'
Chicago Blue R (Colour Index No‘ 474)
D.
.
.
Bmha‘nt Blue G (Colour Index No‘
'
>
Dlréctprown M (colwr Index No‘ 420)
15
of the present invention is to provide a simple
means of ascertaining visually when the saponi?cation has proceeded to the desired extent. .
According to the present invention saponi?ca20 tion is allowed to proceed 1mm a, colour change,
due to the presence of a colouring agent, having
different affinities for the saponi?ed and the unsaponi?ed ester, has progressed to a, predetermined degree, and thereafter removing the colour
sirlpplng may be Carried-Out continuously with‘
01' lmmedlately after saponi?cation 01‘ at any
Subsequent tlme- Any suitable stripping agent
may be employed, 6' g- SOdium hydl‘osulphite
Preferably the dye should be one which ‘can be 20
discharged effectually without the use of a leuco
trope
The following example illustrates the inven
ti0n¢—
25 due to the presence of said colouring agent from
the ester‘
Example
‘
25
A cellulose acetate fabric is saponi?ed in a
The dyejstu?s employed acqording?o the pres‘
ent mventlon may be dyes WhlCh, while they have
little/or no a?inity for the organic ester forming
80 the basis of the arti?cial material, have ana?lnity
bath comprising a 1-3% aqueous solution of caus
tic Soda to which has been added 10% of sodium
Sulphate and _5_1% of benmpurpurin 43 both
calculated on the weight of the fabric_
’
30
for regenerated cellulose, are resistant to alkali
From time to time test portions of fabric are
‘{nder the conditions employed in the saponé?ca'
removed and rinsed, dried, and compared with a
“on treatmentr‘and can SuPSequen?Y be stripped
from the Parnell? Sapom?ed material- when
series of standards consisting of samples of the
same fabric which have been saponi?ed to various
35 such‘ dyestuffs are mcorporated in ‘fhe sawm?ymg
medlum the Progress of the s'fl'pom?ca'tion “(111
marked by a gradual colouring of the arti?cial
under the same conditions as the fabric which is
to be saponi?ed.
materials, the depth of colour increasing as the
degree of sapom?cablon mcreases- when the
saponi?cation is continued until a sample,
after rinsing and drying, exhibits substantially
40 Shade reaches the depth correspondmg to the
degree _of saponi?cation required, which may be
the same shade as the standard which has been
saponi?ed to the desired extent
' ‘
detefrmmei? by Commune the mammal bemg 5?"
In a similar way other suitable cotton dyes,
pom?ed wlth 3' prevlously prepared standard’ 5a"
for instance any of those referred to above, may
poni?cation may be interrupted and the materials
be employed
45 w?i?zdn?leigg?'s most valuable ‘in the sapom_
r
predetermined degrees, and subsequently dyed "
0
45
The principle of the present invention may
?cation of arti?cial materials by batch processes, 2:312; frigging) gageg?ggigcyeégtgeghé123E333:
1
.
for exa'mp‘e m the form of hanks’ cops or other
packages.
In this method it is necessary only to
50 immerse the materials in the saponifying medium
before the saponi?cation process with a dyestuif
‘
_
,
and maintain them there until they have acquired
Whlch has no amnity for cellulose and which W111 50
dissolve out from the regenerated cellulose per
tion of the materials into the alkali medium. Ex
As stated above, any suitable dyestuffs may be
employed which have an a?inity for regenerated
55 cellulose but have little or no a?inity for the
amples of such dyestuffs are mono-carboxylic
and mono-sulphonated azo dyestuffs having an
a?inity for cellulose acetate or the other organic 55
the desired shade.
2
2,129,995
ester of cellulose concerned. According to this
modi?cation of the process the saponi?cation
may be carried out until the original shade of the
.cellulose ester materials has decreased until it
reaches a standard shade.
While the present invention is of particular
importance in relation to the saponification of
arti?cial materials containing cellulose acetate,
it may also be employed in the saponi?cation of
H) materials containing other organic esters of cel
lulose, including mixed esters and ether-esters,
for example cellulose acetate-propionate, cellu
lose propionate, cellulose butyrate, ethyl cellu
lose acetate and oxy-ethyl cellulose acetate.
What I claim and desire to secure by Letters
Patent is:—
1. Process for the saponi?cation of organic
esters of cellulose, comprising treating the ester
with a saponifying medium until a color change,
due to the presence in the saponifying medium
of a coloring agent having different a?inities for
a basis of an organic ester of cellulose, comprising
treating the materials with a saponifying medium
containing a cotton dye capable of discharge
by reduction which has an a?inity for regenerated
cellulose but none for the cellulose ester until the 5
materials have become colored to a predetermined
shade by said dye, thereupon interrupting the
saponification, and thereafter discharging said
dye by treating the materials with a reducing
agent.
10
4. Process for the partial saponi?cation of ?la
ments, threads, ribbons, ?lms and like materials
having a basis of cellulose acetate, comprising
treating the materials with a saponifying medium
containing an amount of the saponifying agent 15
greater than that required to e?ect saponi?cation
to a predetermined degree and a coloring agent
which has an a?inity for regenerated cellulose but
none for the cellulose acetate, until the ma
terials have become colored to a predetermined 20
agent, thereupon interrupting the saponification,
shade by said coloring agent, thereupon inter
rupting the saponi?cation, and thereafter remov
ing the color due to said coloring agent from the
materials.
5. Process for the partial saponi?cation of ?la 25
ments, threads, ribbons, ?lms and like materials
having a basis of cellulose acetate, comprising
treating the materials with a saponifying medium
containing an amount of the saponifying agent
greater than that required to effect a predeter 30
mined degree of‘saponi?cation, and a cotton dye
capable of discharge by reduction, which has an
a?inity for regenerated cellulose but none for
the cellulose acetate, until the materials have
become colored to a predetermined shade by said
and thereafter removing the color due to said
coloring agent from the materials.
3. Process for the saponi?cation of ?laments,
threads, ribbons, ?lms and like materials having
and thereafter discharging said dye by treatment
with a reducing agent.
HENRY DREYFUS.
the saponi?ed and the unsaponi?ed ester, has
progressed to a predetermined degree, thereupon
interrupting the saponi?cation, and thereafter
removing the color due to the presence of said
coloring agent from the ester.
2. Process for the saponification of ?laments,
threads, ribbons, ?lms and like materials having
a basis of an organic ester of cellulose, compris
30 ing treating the materials with a saponifying
medium containing a coloring agent which has an
a?inity for regenerated cellulose but none for the.
cellulose ester until the materials have become
colored to a predetermined shade by said coloring
dye, thereupon interrupting the saponi?cation,
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