US006042890A

United States Patent (19) 11 Patent Number: 6,042,890

Rif et al. (45) Date of Patent: Mar. 28, 2000
54 PROCESS FOR PRODUCING A FOREIGN PATENT DOCUMENTS
STRENGTHENED FIBER ASSEMBLY
698.123 1/1951 United Kingdom.
9507386 3/1995 WIPO.
75 Inventors: Harmut Rif; Heinrich Firgo; 9631645 10/1996 WIPO.
Siegfried Ambrosch; Christian 9637653 11/1996 WIPO.
Schlossnikl, all of Vöcklabruck;
Raimund Jurkovic, Lenzing, all of OTHER PUBLICATIONS
Austria
Goikhman et al., Vysokomol. Soedin., Ser. A (1985), 27(1),
73 Assignee: Lenzing Aktiengesellschaft, Lenzing, pp. 122-126.
Austria Chanzy et al., J. App. Pol. Sci., Appl. Pol. Symp. 37, pp.
239-259 (1983).
21 Appl. No.: 09/173,822
Primary Examiner Erma Cameron
22 Filed: Oct. 16, 1998 Attorney, Agent, or Firm-Baker Botts, LLP
Related U.S. Application Data 57 ABSTRACT
63 Continuation of application No. PCT/AT98/00040, Feb. 25, The invention relates to a proceSS for producing a strength
1998. ened fiber assembly containing cellulosic fibers with the
30 Foreign Application Priority Data cellulose being present in the crystalline Structure of cellu
lose II, by contacting the fiber assembly with an aqueous
Feb. 25, 1997 AT Austria ...................................... 319/97 solution of N-methylmorpholine-N-oxide (NMMO) at
51) Int. Cl." ................................. B05D 1/38; B05D 3/10 elevated temperature and Subsequently washing the fiber
assembly, characterized in that contacting is effected in a
52 U.S. Cl. .......................... 427/354; 427/369; 427/384; manner that from the relation
427/394; 427/396; 427/439
58 Field of Search ..................................... 427/384, 394, –947+0.30xlogot--0.046XT-3.53xC +645xlogoC
427/395,396, 353, 354, 369, 439
wherein t indicates the time in minutes during which the
56) References Cited fiber assembly is contacted with the aqueous NMMO
U.S. PATENT DOCUMENTS solution, T indicates the temperature of the aqueous NMMO
Solution in C. and C is the concentration of NMMO in %
2,179,181 11/1939 Graenacher et al.. by mass, based on the aqueous NMMO solution, a number
3,447,939 6/1969 Johnson .................................. 106/135 in the range of 0.30 to 1.70 results with the proviso that the
3,447,956 6/1969 Johnson. temperature T is smaller than 130 C. and the concentration
3,508,941 4/1970 Johnson .................................. 106/125 C ranges between 70 and 84% by mass.
4,196,282 4/1980 Franks et al. . ... 106/168
5,094,690 3/1992 Zikeli et al. .. ... 106/198
5,589,125 12/1996 Zikeli et al. ............................ 264/187 7 Claims, No Drawings
 6,042,890
1 2
PROCESS FOR PRODUCING A A process and an arrangement for Spinning cellulose
STRENGTHENED FIBER ASSEMBLY Solutions are known, for instance, from WO 93/19230 to
applicant. There, the Spinning Solution is spun in the hot
This is a continuation of application Ser. No. PCT/AT98/ State and the filaments obtained are introduced into a pre
00040 filed Feb. 25, 1998 which is incorporated by reference cipitation bath in order to precipitate the cellulose contained
herein. therein, the filaments being cooled prior to their introduction
BACKGROUND OF THE INVENTION into the precipitation bath. Cooling is effected immediately
after moulding and, preferably, consists in horizontally
The present invention relates to a process for producing a blowing air at the cellulose moulded body.
Strengthened fiber assembly containing cellulosic fibers with
the cellulose being present in the crystalline Structure of German Patent No. 902 427 describes the strengthening
cellulose II, by contacting the fiber assembly with an aque of a fleece of cellulose fibers by means of a lye bath
ous solution of N-methylmorpholine-N-oxide (NMMO) at containing 5 to 15% NaOH. The cellulose fibers are Swollen
elevated temperature and Subsequently washing the fiber 15
by the lye bath and thereby strengthened.
assembly. From WO95/07386 to applicant, a process for producing
For the purposes of this description and the annexed paper is known, in which an aqueous Suspension of com
claims, the expression "fiber assembly' is to denote any kind mninuted cellulose material is mechanically treated and
of wovens, nonwovens or random webs. Subsequently Subjected to a sheet forming procedure, the
During the past years, a number of processes in which Suspension containing tertiary amine oxide. That process
cellulose is dissolved in an organic Solvent, a combination of allows for the production of high-strength paper.
an organic Solvent with an inorganic Salt, or in aqueous Salt A process for Strengthening a fibrous material is known
Solutions, without forming a derivative have been described from U.S. Pat. No. 3,447,956. Strengthening is effected in
that the fibrous material is Soaked with an amine oxide and
as alternatives to the Viscose proceSS. Cellulose fibers made 25
of Such Solutions were given the generic name lyocell by heated to a temperature at which the amine oxide is able to
BISFA (The International Bureau for the Standardisation of strengthen the fibrous material. Proposed fibrous materials
Man-Made Fibres). According to the BISFA definition, are wovens and nonwovens containing natural cellulosic
lyocell is a cellulose fiber obtained from an organic Solvent fiberS Such as, e.g., Wood pulp, cotton, linen, but also
by means of a spinning process. By “organic Solvent', a synthetic fibers such as rayon (viscose fibers). Particularly
mixture of an organic chemical and water is understood by preferred is the treatment of paper with amine oxide. In
BISEA doing so, NMMO apparently is used as a monohydrate in the
To date but a single process for the production of a molten or liquid state or dissolved in a volatile solvent
cellulose fiber of the lyocell type has, however, become 35
capable of being evaporated.
accepted to the point of large-scale realization, namely the From WO 96/37653 fiber assemblies provided with a
amine oxide process. In that process, N-methylmorpholine cellulosic coat, impregnation or sheath are known. Those
N-oxide (NMMO) is preferably used as the solvent. For the fiber assemblies are produced by coating the fiber assembly
purposes of the instant Specification, the term "tertiary on one side with a solution of cellulose in aqueous NMMO,
amine oxides' substitutionally is referred to by the abbre 40 whereupon the layer is coagulated in a water bath.
viation “NMMO", NMMO additionally representing the U.S. Pat. No. 4,196,282 describes the three-component
presently preferred N-methylmorpholine-N-oxide. system NMMO/HO/cellulose and the so-called “dissolu
Tertiary amine oxides have been known for long as tion frame', i.e., those conditions under which the cellulose
alternative solvents for cellulose. Thus, it is known, for 45 dissolves in aqueous NMMO.
instance, from U.S. Pat. No. 2,179,181 that tertiary amine Furthermore, it is known that cellulose fibers may be
oxides are capable of dissolving high-quality chemical pulp Swollen with NMMO (Chancy et al., “Swelling and Disso
without the formation of derivatives and that cellulose lution of Cellulose in Amine Oxide/Water Systems'; J. App.
moulded bodies such as fibers may be obtained from Such 50
Pol. Sci: Appl. Pol. Symp. 37,239-259 (1983)).
solutions by precipitation. U.S. Pat. Nos. 3,447,939, 3,447, SUMMARY OF THE INVENTION
956 and 3,508,941 describe further processes for the pro
duction of cellulose Solutions with cyclic amine oxides The invention has as its object to provide a process of the
being used as the preferred Solvents. In all of those initially defined kind, in which a fiber assembly can be
processes, cellulose is physically dissolved at elevated tem 55
Strengthened without cumberSome evaporation of a volatile
perature. Solvent and without requiring the use, or preparation by
In EP-A - 0 356 419 to applicant a process is decribed, evaporation, of an NMMO monohydrate.
which preferably is carried out in a thin-layer treating The process according to the invention for producing a
apparatus in which a Suspension of the comminuted pulp in Strengthened fiber assembly containing cellulosic fibers with
an aqueous tertiary amine oxide is spread in the form of a 60 the cellulose being present in the crystalline Structure of
thin layer, transported over a heating Surface, while the cellulose II, by contacting the fiber assembly with an aque
Surface of the thin layer is exposed to a vacuum. During ous solution of N-methylmorpholine-N-oxide (NMMO) at
transportation of the Suspension over the heating Surface elevated temperature and Subsequently washing the fiber
water is evaporated and the cellulose can be dissolved Such 65
assembly is characterized in that contacting is effected in a
that a Spinnable cellulose Solution is discharged from the manner that from the relation
thin-layer treating apparatus. –947+0.30xlogot--0.046XT-3.53xC+645xlogoC
 6,042,890
3 4
wherein t indicates the time in minutes during which the
fiber assembly is contacted with the aqueous NMMO TABLE 1.
solution, T indicates the temperature of the aqueous NMMO Ex NMMO Concentration Temperature Time Value
Solution in C. and C is the concentration of NMMO in %
by mass, based on the aqueous NMMO solution, a number 1. 84.O 8O O.O8 O.95
in the range of 0.30 to 1.70 and, preferably, in the range of 2 82.O 8O O.O8 1.30
0.5 to 1.5 and, in a particularly preferred manner, in the 3 82.O 70 O.17 O.94
4 80.6 70 O.SO 1.2O
range of 0.8 to 1.2 results with the proviso that the tem 5 80.6 8O O.O8 1.42
perature T is smaller than 130° C. and the concentration C 6 80.6 8O 0.50 1.66
ranges between 70 and 84% by mass. 1O 7 78.2 70 1.OO 1.29
8 76.2 70 O.SO 1.OO
DETAILED DESCRIPTION OF THE 9 76.2 8O O.17 132
1O 73.9 70 4.OO O.81
PREFERRED EMBODIMENT 11 74.2 8O O.SO 1.07
12 74.2 90 O.17 139
The invention is based on the finding that, for Strength 15 13 71.9 90 2.OO 1.02
ening an assembly of cellulose fiberS Such as, e.g., a 14
15
71.9
7O.O
1OO
1OO
O.17
O.SO
1.16
0.49
nonwoven, the three parameters mentioned, i.e., the concen
tration of the NMMO solution, its temperature and the time
of impregnation, apparently are essential and Sufficient and
that, in addition, they must be chosen Such that the above
relation is met. If, in contrast, these parameters are chosen Examples 1 to 15 fall within the scope of invention, since
Such that a value Smaller than 0.30 results from the relation, the values resulting from the abovementioned relation with
no strengthening of the assembly will be obtained. If, on the the NMMO concentrations, temperatures and times of
other hand, the parameters are chosen Such that a value of 25
impregnation are within the range defined by the invention.
more than 1.70 results from the relation, the dissolution of All of the nonwovens were found to be strengthened after
the fiber assembly in the NMMO solution is observed. having been treated according to the invention.
In the process according to the invention, the temperature
T preferably is smaller than 100° C.
A particular embodiment of the process according to the Similarly good results could be obtained with a nonwoven
invention is characterized in that the fiber assembly is comprised of fibers produced according to the amine oxide
pressed before Washing. Pressing may be effected in a proceSS.
Simple manner, e.g., by conducting the nonwoven between
two rolls exerting a pressure on the fiber assembly. 35
The use of a fiber assembly containing fibers produced at COMPARATIVE EXAMPLES
least partially according to the amine oxide process or the
Viscose process has proved particularly Successful in the
process according to the invention. 40 For reasons of comparison, additional tests were carried
The invention will be explained in more detail by way of out according to the general working instruction, yet the
the following examples. parameters had been chosen Such that the relation was not
met. These examples are Summarized in Table 2.
GENERAL WORKING INSTRUCTION
45
slightly needle punched Viscose nonwovens each having TABLE 2
a size of 12x16 cm and a weight per unit area of about 70 Ex. NMMO Concentration Temperature Time Value
g/cm were immersed into an aqueous NMMO solution 16 82.O 90 0.17 186
between two Sieves and allowed to impregnate, whereupon 17 80.6 8O 1.OO 1.75
the impregnated nonwovens were pressed by means of a 50 18 80.6 90 O.08 1.88
laboratory press (pressing pressure: 3 bars, corresponding to 19
2O
78.2
78.2
8O
90
2.OO
O.08
1.84
1.88
a line pressure of 12.6 N/mm at a nonwoven width of 12 21 76.2 90 O.SO 1.92
cm). After this, the pressed nonwovens were washed with 22
23
76.2
74.2
1OO
1OO
O.08
O.08
2.14
1.75
tap water for 15 minutes. 55 24 72.2 70 4.00 O.29
25 72.2 12O 4.00 2.59
EXAMPLES 26 7O.O 8O 12.0 -0.10
27 7O.O 90 2.OO O.21
According to the above working instruction, Several tests 28 7O.O 1OO O.08 O.25
were carried out, the parameters to be set according to the 60
invention, i.e., the concentration of the respective NMMO
solution (in 96 by mass, based on the total mass of the We claim:
Solution), its temperature (in C.) and the time of impreg
nation (in minutes) having been chosen as indicated in Table 1. ProceSS for producing a strengthened fiber assembly
1 below. All of the examples comply with the above-defined 65 including fibers of cellulose, Said cellulose having a struc
relation. The values resulting with the respective parmeters ture wherein Said Structure is the crystalline Structure of
are also apparent from the Table. cellulose II, which process comprises the Steps of:
 6,042,890
S 6
providing an aqueous Solution of N-methylmorpholine 2. A proceSS in accordance with claim 1, wherein the value
N-oxide, is a number in the range of 0.5 to 1.5.
contacting Said fiber assembly with Said aqueous Solution 3. A proceSS in accordance with claim 1, wherein the value
of N-methylmorpholine-N-oxide at elevated tempera is a number in the range of 0.8 to 1.2.
ture in accordance with the following relation So as to 4. A process in accordance with claim 1, wherein T is less
obtain a strengthened fiber assembly: than 100° C.
947+0.30xlogo-0.046xT-3.53xC+645xlogo)C=value 5. A proceSS in accordance with claim 1, further compris
ing pressing Said strengthened fiber assembly prior to wash
where t is the time in minutes during which said fiber ing.
a SS embly is contacted with Said aqueous 6. A process in accordance with claim 1, wherein Said
N-methylmorpholine-N-oxide solution, T is the temperature
of said aqueous N-methylmorpholine-N-oxide solution in fiber assembly contains fibers at least partially produced by
C. and C is concentration of N-methylmorpholine-N-oxide an amine oxide process.
in percent by maSS, based on Said aqueous 15 7. A process in accordance with claim 1, wherein Said
N-methylmorpholine-N-oxide solution, and wherein value fiber assembly contains fibers at least partially produced by
is a number in the range of 0.30 to 1.70 when T is less than a Viscose process.
130° C. and C is in the range of 70 and 84% by mass, and
Washing Said Strengthened fiber assembly.
 UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION
Page 1 of 2
PATENT NO. : 6,042,890
DATED : March 28, 2000
INVENTOR(S) : Ruf et al.
It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
corrected as shown below:

ON THE COVER:
57) ABSTRACT, line 11: “indicatcs thc tcmpcrature of
thc aqucous' should read
- indicates the temperature of the aqueous--
IN THE CLAIMS:
Column 5, line 7: “947' should read
- -947-; and "logo)" should read
- logo --
Column 6, line 14: "proccss' should read
- proceSS --, "accordance' should read
-- accordance --, and "whorcin' should read
-- wherein --
 UNITED STATES PATENT AND TRADEMARK OFFICE
CERTIFICATE OF CORRECTION
Page 2
PATENT NO. : 6,042,890 ge 2 of 2
DATED : March 28, 2000
INVENTOR(S) : Ruf et al.
It is certified that error appears in the above-identified patent and that said Letters Patent is hereby
corrected as shown below:

Column 2, line 17: “mninuted' should read

-- minuted --
Column 3, line 45: "slightly' should read
-- Slightly --
Column 3, line 65: "parmeters' should read
-- parameters --

Signed and Sealed this

Twenty-fourth Day of April, 2001

Zaaé, f-34.
NICOLAS P. GODC

Attesting Officer Acting Director of the United States Parent and Trademark Office